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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The principle of the mise-á-la-masse method is to earth one current electrode of a pair in a conducting mineral show (in a borehole, in an outcrop etc.) and measure the resulting distribution of electric potentials. The distribution will, to some extent, reflect the geometry of the ore mass of which the mineral show forms a part.In a mise-á-la-masse survey of a lead-zinc deposit in Central Sweden electric potentials were measured on the surface of the ground as well as in some 25 drillholes, in either case with earthings (successively) in three different parts of the irregular ore deposit. Besides this, measurements were made in drillholes with earthings in two further drillholes.Geologic correlation between the drillholes is difficult in the present case on account of the irregular geometry of the ore deposit. However, the mise-á-la-masse measurements clearly showed the dip and the pitch of the ore body, established connections between the different ore widths encountered in the various holes, and yielded information about the shape of the ore mass.In particular, the survey showed that the ore lenses must be crescent-shaped rather than tabular, and the dip was indicated to be westerly, instead of easterly as originally presumed.Three-dimensional models of equipotential surfaces were constructed from the observed drillhole and surface potentials (using transparent plastic sheets and thin copper wire) and these helped to elucidate the mass geometry further.The surface and underground potential data collected in the present case should be of nterest to geophysicists working on analytic continuation problems.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The author comments the techniques and methods used in continuous seismic profiling by the Monaco Oceanographic Museum during the last five years.Pinger probe give informations on the Mud layering and thickness. On the shelf or in abyssal plains, boomer and sparker are employed and allow to rise various geological conclusions. South coast of France, continental shelf in the Gulf of Lion, abyssal plain of the Ligurian Sea and Lake of Geneva are the areas concerned to with the results.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The author proposes the parameter Δ2/ΔT1 for possible application in aeromagnetic surveying making use of already available gradiometer systems equipped with sensors separated vertically.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Geophysical field equipment has undergone rapid changes in the past decade; from simple AGC amplifiers and galvo cameras to binary gain switching amplifiers and digital recorders, all in an attempt to keep pace with the new geophysical interpretive methods developed, and the growing acceptance of the terminology, methods, and philosophy of communication theory.The additional tools of the digital recorder and digital computer make it possible to utilize these new techniques in geophysical processing. Accomplishing these new techniques demands severe requirements on the digital field recording process in handling the decreasing energy return from the seismometer, and to fully realize the capabilities of digital techniques in reducing data. Simple automatic gain control may be used. However, in the more sophisticated interpretive methods, such as autoregression and deconvolution, it is necessary to reconstruct the actual energy levels in the computer. Recording the control signal used in master AGC or programmed gain control may prove satisfactory; however the accuracy of control versus gain is limited to I% for such analog instrumentation.To utilize the computer to its fullest extent, and to accurately perform these new techniques, requires an accuracy of I% or better. This accuracy is obtainable by using a step gain control where the gain is increased by fixed steps in which each step represents a gain in amplification by a constant factor. The accuracy in this case can be made dependent only on the tolerance of resistors used as attenuators or feedback elements. Preferably the constant factor of gain steps should be a number easily handled by the computer. By using 6 db steps it becomes a simple matter to shift binary numbers, such as multiplying or dividing by 10 in the decimal system.The requirements or parameters for such an amplifier system, and the elements of the amplifier necessary to achieve these requirements are presented.
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  • 5
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Consideration is given to the use of a configuration of four electrodes set in a square array for resistivity measurements.It is found that, by passing current successively between different pairs of electrodes, an apparent resistivity can be determined which is both more sensitive to the position of the array centre and less dependent on orientation than the measures usually obtained with colinear arrays of electrodes. At the same time the observations made enable the degree of the departure of local conditions from conditions of lateral homogeneity to be assessed.Theoretical and practical examples of the use of this electrode system are given and the use of the system both as a tool in mapping and in depth investigations is considered.It is shown that provided electrode spacings are suitably arranged the results of a probe carried out using the square array can be interpreted by conventional methods.The system is shown to have particular advantages in the investigation of lateral resistivity variations and the reduced dependence on orientation makes possible the recasting of interpretation data in an orientationally invariant form with a consequent drastic reduction in the number of type curves required for a particular problem.
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  • 6
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A large self-potential anomaly was outlined in 1963–64 at Tantahuatay near Hualgayoc in the Andes of northern Peru. Peak value recorded was–1842 millivolts–thus making it one of the strongest, or perhaps the strongest, SP anomaly ever measured. A lack of detailed geological data precludes the formulation of an adequate explanation for the Tantahuatay anomaly, but geological and mineralogical similarities with the well-documented Venencocha anomaly near Cerro de Pasco, Peru (Kruger and Lacy, 1949), suggest that the anomaly arises from sulfuric acid associated with the mineral alunite. The anomaly obviously cannot be explained by the half-cell mechanism of Sato and Mooney (1960), who place a limit of 700 millivolts on self-potential anomalies over sulfide bodies. Further study of the Tantahuatay anomaly would be of interest in understanding self-potential mechanisms in general.
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  • 7
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Book review in this articleF. S. Grant and G. F. West, Interpretation Theory in Applied Geophysics, McGraw-Hill Comp., New York, 1965, 583 pp., price $ 17.50.Archaeo-Physica. Technische und naturwissenschaftliche Beiträge zur Feldarchäologie. Mit Beitragen von E. Le Borgne, I. Scollar, J. D. Mudie, J. Görier, H.-J. Appel, G. Strunk-Lichtenberg, Böhlau Verlag, Köln, Graz, 1965, 202 pp., 124 fig.H. Takeuchi, Theory of the Earth's Interior, Blaisdell Publishing Company, Waltham (Mass.), Toronto, London, 1966, 131 pp.G. D. Garland, The Earth's Shape and Gravity, The Commonwealth and International Library, Geophysics Division, Pergamon Press, Oxford, London, Edinburgh, New York, Paris, Frankfurt, 1965, 183 pp., price: 17s 6d.
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  • 8
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The electromagnetic field radiated from a magnetic dipole lying on the ground is considered, in the extremely low frequency range (DC to 20 000 Hertz).Theoretical and experimental data are given on the characteristics of the surface wave (vanishing wave) generated at the air-ground interface, in the case of an homogeneous subsurface.The case of a subsurface with electrical resistivity varying with depth is considered.It is shown how the above-mentioned characteristics may be applied in the quantitative investigation of the electrical resistivity of the subsurface as a function of depth, in a method using the measurements on the ground of all the components of the radiated field: horizontal electrical components, vertical and horizontal magnetic components.
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  • 9
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Book review in this articleHandbuch der Physik/Encyclopedia of Physics, Ed.: S. FlüggeThe Aurora. By S.-I. Akasofu, S. Chapman and A. B. Meinel.Time-Variations of Cosmic Rays. By S. E. Forbush.Magnetic Properties of Rocks and Minerals. By T. Nagata.
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  • 10
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A formula is developed for the vertical magnetic field due to an alternating current passing through a long horizontal cable placed on a two-layer ground. The variations of the phase and amplitude ratio of the vertical field, along profiles perpendicular to the cable line are investigated. Within the limits encountered in practice, it is found that if the upper layer is conductive, as compared to the lower layer, the phase may vary appreciably whereas the amplitude ratio changes as in the case of vacuum.
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  • 11
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Book review in this articleN. A. Ogil'vi, D. I. Fedorovich, Groundwater Seepage Rates. English translation by N. H. Choksy, Consultants Bureau, New York 1966, 33 pp., 12 fig.
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  • 12
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Mapping of fault patterns is an important part of geophysical exploration. A computerized digital template analysis method is described which tests gravity maps for the effects of faults by comparing measured gravity data with calculated master curves. The interpreted gravity data are incorporated in a tectonic map using geological symbols and units, for ready use by the geologists.Tectonics can be investigated by gravity detailing if the smallest undulations on the Bouguer map are taken into consideration. Up to now, residual and derivative gravity maps have explained gravity effects by assuming spherical bodies which are almost unknown in geology. The method discussed here uses tectonic elements, such as fault-blocks and dikes as a basis of interpretation instead of the spherical bodies of the conventional interpretation methods.Gravity data can be easily and relatively cheaply obtained in the early phases of exploration by area wide spot coverage following lines of easy access such as roads, etc. Seismic studies, by contrast, have the disadvantage of being executed along predetermined profile lines. Only after sufficient detailing do seismic profiles permit-if at all -an areal mapping of faults. Thus a tectonic map is obtained only at the end of a geophysical survey instead of being available prior to the planning of costly seismic profiles. The use of gravimetric data and their interpretation by the suggested method provides tectonic detail maps in the early phases of geophysical studies.In addition, this article discusses a general geophysical interpretation method, using the investigation of faults by gravity as an example. Applications of this method for different gravity and magnetics problems as well as for combined interpretations are outlined. Detailed case histories will be published in later articles.
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  • 13
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: To be able to make use of all existing probe interpretation techniques, it is desirable that field resistivity observations be conducted in such a way that it is possible to construct an equivalent curve for the surface variation of potential about a point source. Further, the usual parallel layer interpretation will only be justified in as much as the observed potential curve is compatible with such a subsurface geometry. Thus, whilst a potential curve may be constructed from suitable finite potential differences obtained using a Wenner configuration of electrodes, it can be shown, using the tri-potential technique of measurements, that these potential differences may arise partly from lateral resistivity variations.In this paper, a ladder network technique is employed to display these lateral effects and an adjustment method proposed to reduce them. The adjusted potential differences obtained form a consecutive series suitable for summation to give the potential function. These values are subject to further minimum adjustments required for them to comply with slope and curvature conditions for a layered medium. After forming the potential curve by summation, a final numerical smoothing process is carried out. From this smoothed potential curve, corresponding Wenner and Schlumberger curves can readily be derived for interpretation.The method proposed thus attempts to extract from the observed data the maximum part which can be reconciled with a purely depth variation of resistivity. A method is also proposed for compounding the ‘errors of closure’ of the network to provide a Lateral Inhomogeneity Index which gives a measure of the departure of the observed data from the basic interpretation requirements.The method involves no great labour, but can readily be programmed for a computer if desired. Examples are given of the application of the method to field observations. In the interest of objectivity, the final smoothing has been confined to a single stage but in certain very extreme examples a further stage may prove desirable.
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  • 14
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: In one geophysical survey over a salt dome in the Gulf of Mexico, data taken from a single magnetic and seismic shipborne traverse demonstrated significantly the importance of magnetic measurements. The reduced magnetic and seismic profiles were integrated with gravity measurements from an earlier survey demonstrating the value of obtaining simultaneous geophysical data. The traverse was approximately 25 miles in length, 135 miles southeast of Galveston, Texas. The observed gradient averaged approximately 2 gammas per 1000 feet and crosses the southwest corner of a large shallow salt dome called the Way Dome. The recorded magnetic profile over the salt dome shows a negative magnetic anomaly extending for approximately 12 miles with a maximum amplitude of approximately 20 gammas. This negatively anomaly is due to the negative susceptibility contrast between the salt and cap rock that truncates the surrounding parent sediments. The shape of the negative anomaly correlates well with the continous seismic record and clearly delineates the topographical and structural features of the salt dome. The recorded analog magnetic profile was replotted, with both the regional gradient and time variations removed, which makes the observed anomaly much sharper than is noticeable on the original recorded strip chart record. A theoretical magnetic anomaly was calculated using a computer program for comparison to the observed anomaly. The results showed good correlation.
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  • 15
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
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  • 16
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    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
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  • 17
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Amplitudes of the vertical ground motion are larger in the critical angle region than in the near vertical region, especially amplitudes coming from deeper boundaries or interfaces with small velocity contrast. Four basic boundary models are used to derive specific travel time patterns for first order and higher order interfaces. The transition from reflected waves to diving waves in the supercritical angle region is shown for the different models.Examples from wide angle surveys in Bavaria and in the Buchara region in the USSR have many characteristic similarities. Travel time patterns and asymptotic velocities are almost identical. The most important boundaries of the continental crust - the Mohorovč Ić discontinuity and the top of the crystalline basement - correspond to two boundary models mentioned before. Amplitude and frequency investigations have been used to derive items of the M-discontinuity. It is certainly a gradient zone and seems to have a lenticular structure with material of stepwise different velocities.
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  • 18
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: When a small, transparent replica of a seismic section is illuminated by a homogeneous beam of coherent, monochromatic parallel light a diffraction pattern is created that is representation of the double Fourier spectrum of the recorded seismic waves, i.e. their spectrum in terms of frequency, f, and apparent wave number, k.Masking selected parts of this diffraction pattern causes the spectrum to be filtered: the recomposition of the filtered spectrum then provides a filtered section.The ideal seismic section for this purpose would be a continuous variable density section obtained from recording made at every point of the seismic line. The light transmission coefficient (in terms of light amplitude) at each spot of the replica should be linearly related to the instantaneous seismic signal strength at the spot on the seismic section to which it refers.Unfortunately we cannot make recordings at every point of a seismic line and in our practically realisable recordings we have to be content with sampling in the direction of the location coordinate x. This means that with variable density recordings aliasing will be present and evident in the spectrum obtained in the direction of k; furthermore, the aliased spectrum is also multiplied by a sine function of k because the recording obtained at a given station is not presented on the seismic section as a single line along the time axis, but occupies the entire width of the trace.The diffraction patterns created by variable density recordings of dipping sine waves, including clipped recordings, and of the effect of dip filtering in such sections are discussed. The efficiency of dip rejection is shown to decrease with increasing dip.The diffraction pattern of a variable density recording is found to be characterised by a relationship between point pairs in the pattern.No such simple relationship has been found for the diffraction pattern of a variable area section; the spectra of such VAR sections belong to a very special class, because the amplitude transmission coefficient has only two values, viz. 0 and 1.Consequently, selective masking of the diffraction pattern of a VAR section may give rise to a filtered profile that does not look like a VAR section at all.General statements about the diffraction pattern of VAR sections are hard to give, because the transmission coefficient at a given point in the replica is not proportional to the signal level in the seismic section at the relevant point.In the case of VAR presentation of harmonic waves it was found that, as well as the aliasing effect in the k direction, higher harmonics of the frequency are also introduced.Some synthetic examples are given that show dip filtering to be less effective with VAR than with variable density recordings.Some arguments are advanced in favour of the opinion that high-pass filtering of VAR sections will have less success than low-pass filtering. This is demonstrated by two synthetic examples.
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  • 19
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The theory is explained and practical applications are shown for a numerical procedure in seismology. Particularly the problems concerning the generation of waves under the action of external pressures, and their propagation, in non-homogeneous, both elastic and absorbing media, have been carried out. These problems have been assumed mono-dimensional and refer to plane and spherical waves.The procedure is based on the solution, by means of series, of the wave differential equation, non-homogeneous, and with non-constant coefficients. It is a direct numerical method whose advantage is, mainly, the possibility of tackling, without great difficulties, problems regarding non-homogeneous elastic and absorbing media.On the contrary the methods which require the theoretical expression of the solutions by means of formulae, generally, present conceptual and numerical difficulties.As examples of application of this procedure, the following cases have been carried out by means of numerical calculations.a) Propagation of a wave, initially of symmetrical shape, in a viscoelastic medium; from the results it appears that the wave propagates without losing its symmetry, i.e. without sensible dispersion. A theoretical analysis has been carried out to justify this result, showing that the dispersion in viscoelastic media is noticeable only for relatively high frequencies. It seems that the practical absence of dispersion in field experiments do not exclude necessarily the viscoelastic character of absorption.b) Generation of plane waves under the effect of a uniform pressure distributed on the plane surface of a medium. The way the length and the shape of the generated wave depends not only on the type of pressure acting on the surface but also on the near surface impedance variations has been studied.c) Generation of a spherical wave under the action of a pressure in a spherical hole.The examples treated show how the length and shape of the wave depends on the radius of the hole. Particularly the frequencies of the wave spectrum are proportional to this radius, for a given type of pressure acting in the hole.The characteristics of this procedure would also permit the study of media for which the stress-strain relations are not univocal and linear (non linear absorption). This study, interesting for the wave propagation in rocks, is worth while to be carried out in a special paper.
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  • 20
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: For the computation of the vertical component Hz of the magnetic field of a horizontal A.C. dipole lying on the earth's surface, a recurrence formula is presented for a horizontally stratified half space, to obtain the (n+ 1)-layer case from the w-layer case.By means of several computed diagrams for the two-layer case, Hz can be determined for different ratios of conductivity of the subsoil and that of the overburden. Thereby the distance from the dipole as well as the layer thickness h are expressed in terms of the wave length A of a plain wave in the overburden. Assuming a sufficiently large conductivity difference, the results show that evidence about the subsurface conditions can be obtained if the distance between the measuring coil and the dipole is of the order of A/3, and if the thickness h of the layer varies within the range A/100 〈 h 〈 A/6.As an example for the 3-layer case, a nonconducting intermediate layer is assumed.
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  • 21
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A nomogram is presented which enables evaluation of the components of magnetic attraction of a homogeneous finite rectangular prism, and of gravitational attraction due to a uniform rectangular lamina.In practice any three-dimensional body could be approximated by a number of right rectangular prisms of varying dimensions governed by the shape of the body. The magnetic attraction of the whole body is then obtained by numerical summation of the effects of the constituent prisms.For evaluating the gravitational effect, the cross-section of the body corresponding to each elevation contour is approximated by a number of rectangular laminae (or by a stepping polygon) the attraction of which can be determined with the aid of the same nomogram. The total gravitational attraction of the body is obtained by a process of graphical integration along the vertical axis.
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  • 22
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: In [50] and [51] a theory has been developed relating formation factor, permeability and porosity of porous sedimentary rock by means of statistical parameters of the pore system, and further, tying those statistical parameters to other macroscopically measurable quantities like capillarity, capillary retention, flow dispersion etc. This paper deals with experimental methods and apparatus for checking the theoretically derived relations using columns of packed loose or artificially consolidated sands or other granular matter. Some initial experiments, mainly intended for checking out equipment and methods are reported. The discussion of the results so far shows good agreement with the theory in most cases, except for the irreducible water saturation. However, for a definite statement on the general validity of the theory more data must be accumulated.
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  • 23
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    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: Some of the methods such as regional removal and second derivative calculations which can be used to outline anomalies on potential data maps can be thought of as a filtering operation. The analysis and design of such two-dimensional filters by means of direct and inverse two-dimensional Fourier transforms have been considered.An analysis of several published sets of second derivative coefficient sets indicates that, in general, they are not a good approximation to the theoretical second derivative filter. Alternate methods of designing regional removal and second derivative filters are discussed. The properties of various two-dimensional filters are further illustrated by means of maps obtained from the convolution of several of these filters with a set of observed field data. These maps show the large changes in anomaly shape which can result from the inclusion or rejection of various wavelength components.
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  • 24
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Integration of the continuous seismic reflection profiler with the marine refraction method on engineering surveys offers a solution to hidden layer problems, allowing both layer velocity and thickness to be computed.
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  • 25
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    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: This paper is the follow-up of an earlier paper by the same author on the calculation of standard-graphs for horizontally stratified subsoils. The method which was developed in that earlier paper was destined for handwork; it was laid down in master-tables. The present paper deals with the presentation of similar methods to the computer expert in purely mathematical denotation. Two different denotations are described for the calculation of the image pole strengths involved. The first denotation is an improved version of Watsons formulae; it gives the total strengths. The second denotation preserves the character of successive approximations as described in the previous paper. Both denotations have been worked out until a six layer resistivity profile, but actually there is no limitation to the number of layers. There is no restriction to the resistivities of any layer. The only condition is now that all interface depths must be integers.This paper is followed by a paper on the relevant computer program by Argelo in this same issue
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  • 26
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Book review in this articleJ. Frihagen, Electron Density Profiles in Ionosphere and Exosphere, North-Holland Publishing Company, Amsterdam, 1966, price N. fls. 60,–.J. A. E. Allum, Photogeology and Regional Mapping, Pergamon Press, London, 1966, 107 pages, 16 plates, 23 figures, price 17 s 6 d net.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: High precision gravity surveys have to be examined at different points of view: the accuracy which one can expect on the final results, regardless to their distribution, the shape and amplitude of the expected anomalies, depending on these factors, which grid of stations is convenient in each particular case.Under certain condition, using an appropriate procedure, involving strict criteria, it is possible to get on the Bouguer map the same accuracy as the reading one.However an accuracy closed to 0,01 mgal does not imply that anomalies as 0,01 or 0,02 mgal deserved attention. Numerous factors limit our appreciation of significant anomalies to 0,05 mgal, may be a little less.When cavites are concerned, it is always necessary to define the extreme dimensions an depth of volumes which may give detectable anomalies.Some example are given illustrating different aspects of this particular type of geophysical prospecting.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: Several papers presented at the last SEG Convention in Houston by Schneider, Backus et al have shown how important and fruitful it was to obtain a continuous knowledge of the velocity functions and they have solved their problem by a Dynamic Correlation Analysis. Our purpose is to introduce here a method based on the best summation of a set of traces instead of the best correlation.Practically, this approach has several advantages:1) Two traces only can be correlated at each step whereas the summation can bear on any number of them;2) Optimizing the summation is actually what we are looking for since, at the long end, the success of the improvement is evaluated from the compositing of several traces either weighted or not.On the other hand, an advantage of correlation is the possibility of adding correlations obtained at several places in a same neighbourhood in order to improve the results. With the summation method this is feasible only when dips are inexistent: we shall see that the difficulty due to the dip effect can be turned around.The basic principle of the method can be summed up as follows: traces relating to a same reflection point are considered; several composites are made, each after applying different move out corrections ranging widely around an estimated adequate velocity function. At each time coordinate, the best adapted velocity function, i.e. the one that yields the best phase relation between reflected events, corresponds to the composite trace the average amplitude of which is the largest.This way, the velocity function corresponding to primary reflections as well as those corresponding to multiple reflections can be established accurately.Some examples are shown.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: The problem of elastic waves–from point sources–in layered media is solved in a general and elementary way. Only the simplest principles of the Theory of Functions are necessary. The solutions can immediately be used for numerical applications.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The symmetry shown, by the function describing the magnetic anomaly due to a dyke or vertical fault step leads to a method by which an observed profile may be adjusted to conform with that symmetry. By making these adjustments a minimum the ideal dyke or fault profile closest to the observations is constructed. In three of four possible situations this is interpreted by simple geometry.Parallelpiped models may be transformed into two dykes for symmetry analysis. Depth limited models are not so amenable, even in special cases.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The use of digital recorders and computers in seismic exploration promises major enhancement of the quality of final documents available to interpreters. The ultimate objectives of recording and processing remain what they always have been:1 Record the reflection wavelet as a function of time; this requirement has been met with satisfactory accuracy for a number of years.2. Record the reflection wavelets with sufficient fidelity to permit the interpreter to recognize them.Various factors affect our ability to achieve this second objective. Certain recording errors are associated with digital recording systems. However, an understanding of the sources of error will enable the operator to use his system properly and to estimate the noise level or inaccuracy of field recordings. Field operations do not require rigorous error analysis; in most cases a satisfactory approximation can be obtained from simple calculations.Three types of “noise”–seismic, instrument and power line–introduce errors. Factors which contribute to over-al recording system error include specifically input noise, power supply ripple, crosstalk, A-D conversion error, quantizing noise, aliasing, distortion. Examination of each component of a recording system, permits the determination of its ultimate effect on the over-all noise level–or error level–of the entire system.Many of the error sources produce statistically independent noise which is not correlative. Where this is true, error voltages from various sources may be combined by taking the square root of the sum of the mean square noise voltages, giving a result slightly greater than the largest single voltage if one source is much greater than any other source. This simplification can be used to estimate over-all system noise levels. Distortion and crosstalk depend on signal amplitude and should be added algebraically in each category. Each final sum should be used as a statistically independent noise source with respect to other system noise sources.Using the foregoing examples and simplified system for estimating over-all system noise, and assuming that much of the distortion (which limits signal/instrument noise ratio to 54 db) can be removed by filtering, we determine that the combined effect of all sources of error is to reduce the system S/N ratio to approximately 74 db.With proper care digital field recording systems can produce very good field records, and exotic computer processes can enhance signal and reduce various forms of noise. However, one always must recall that the level of confidence which one can place in an interpretation of seismic data must be dependent on a knowledge of the accuracy of the basic data.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: The Terrapak is a new seismic energy source of the surface energy source type. Essentially, the Terrapak consists of a compressed air piston which transmits a shock to the ground by means of a striker plate attached to the piston rod. The Terrapak is truck-mounted together with its ancillary equipment. Shocks can be generated at 8 second intervals, and although the weight of the striker is relatively low (approximately 1400 Ibs) the impact velocity exceeds 66 ft/sec. The energy available is about 85,000 ft. lb., which is equivalent to that produced by conventional weight-dropping methods. The power spectrum of the seismic wave produced by the Terrapak is spread out towards the higher frequencies because its impact velocity is greater than that of a dropping weight.There is a noticeable difference between noise records made with the Terrapak and noise records made with a conventional weight-dropping technique. The same noise frequencies are found in both cases, but low frequency noise is stronger with weight dropping than with the Terrapak, whereas the intermediate frequency reflections obtained using the Terrapak are more suitable for correlation.The expansion of the compressed air generates a sound wave, the effects of which must be eliminated by the use of multiple geophone arrays. A spectrum analysis of the records has confirmed that the waves produced by the Terrapak are rich in intermediate frequency components. This facilitates the picking of reflections in normal areas where the apparent frequency of the reflections is about 30 to 35 c/s.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: This paper includes publication of two algorithms, to be processed on a digital computer. The algorithms are based upon the two mathematical denotations, presented by Dr. J. C. van Dam in this same issue. The computer programs are written in Algol, in the form of procedures (i.e. subroutines to be activated from a surrounding Algol program).Each of the two procedures is preceded by a numerical analysis. Some remarks are made about the reliability of each of the two procedures, the production and the computing time required.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: The theory of statistical communication provides an invaluable framework within which it is possible to formulate design criteria and actually obtain solutions for digital filters. These are then applicable in a wide range of geophysical problems. The basic model for the filtering process considered here consists of an input signal, a desired output signal, and an actual output signal. If one minimizes the energy or power existing in the difference between desired and actual filter outputs, it becomes possible to solve for the so-called optimum, or least squares filter, commonly known as the “Wiener” filter. In this paper we derive from basic principles the theory leading to such filters. The analysis is carried out in the time domain in discrete form. We propose a model of a seismic trace in terms of a statistical communication system. This model trace is the sum of a signal time series plus a noise time series. If we assume that estimates of the signal shape and of the noise autocorrelation are available, we may calculate Wiener filters which will attenuate the noise and sharpen the signal. The net result of these operations can then in general be expected to increase seismic resolution. We show a few numerical examples to illustrate the model's applicability to situations one might find in practice.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: In order to adequately understand the complicated, anelastic processes governing wave propagation in soils or highly weathered rock it seems desirable first to have available a convenient laboratory material for such propagation studies the frequency dependent rheological parameters of which are known beforehand. A property measurement program has been conducted to determine the complex Young's modulus and the complex shear modulus of a commercially available viscoelastic material over a broad spectral region.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: In the year 1958 the Service for Water Management of the „Rijkswaterstaat” started its program of geo-electrical resistivity prospecting in the western part of the Netherlands. The aim of this program was to obtain data on the salinity distribution of the ground water.The ground water regime in this part of the Netherlands is most intricate. This is due to the geological and geo-hydrological conditions and to the low elevation of the land. Many reclaimed areas are up to several metres below mean sea level.The resistivity data obtained are closely related to the salinity of the ground water. On the basis of bore hole data it was even possible to arrive at calibration curves for the salinity of the ground water in sand deposits. Under special conditions it was also possible to draw conclusions with respect to the presence of less permeable formations as e.g. clay layers.Some remarks are given on the practical performance and the interpretation of the measurements.A review is given of the work done until now. Some results are shown by means of maps of the salinity distribution of the ground water in the western and northern parts of the Netherlands.Two examples are described of the use of the data obtained during the survey in the province of Zuid-Holland.Another two examples are presented of detailed investigations for special purposes in relatively small areas.
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    Geophysical prospecting 15 (1967), S. 0 
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    Topics: Geosciences , Physics
    Notes: In mountainous areas it is an inadequate procedure to reduce gravity observations by merely subtracting the effect of an infinite flat slab of material between the station and sea-level, and adding a terrain correction. A programme is described which directly computes the effect of masses above sea-level, and mass-deficiencies below it; as well as the effect of compensating masses under the Pratt and Airy isostatic systems. As an example, the method has been applied to a regional gravity survey of Papua and New Guinea where it is seen to remove the usually high correlation of the Bouguer anomaly with local topography.
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    Journal of sensory studies 16 (2001), S. 0 
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Judges rated the intensity of NaCl solutions and orange drinks of varying sweetness using category scales and line scales. They performed under four response conditions that varied in reliance on memory: (1) verbal response (2) written response with no retasting and the response sheet removed (3) written response with a single response sheet which allowed past scores to be reviewed and amended but with no retasting (4) the same as ‘3’ but with retasting. Discrimination errors decreased from conditions ‘1’ through ‘4’ indicating how allowing judges to ‘refresh the memory’ improved discrimination. The cognitive processes involved in rating and consequences for scaling protocols and the experimental design for descriptive analysis are discussed in the light of these findings.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of sweetener type, sweetener concentration, and fruit flavor on the sensory attributes of soy fortified yogurt were determined. Soy fortified dairy yogurts were made by the addition of soy protein concentrate (0, 2.5, 5%) to standard yogurt mixes prior to fermentation. Sweetener type (sucrose, fructose, sucrose/fructose) and sweetener concentration (6, 8, 10%) were incorporated into yogurts in a split plot experiment with soy concentration as a subplot factor. Flavor effects (plain, lemon, strawberry) were studied in a 3 × 3 factorial experiment (soy concentration × flavor). A trained descriptive panel (n=13) evaluated yogurts for seven flavor and aroma terms. Sweetener type had no effect on sensory properties with the exception of perceived sweetness. Soy flavors and astringency decreased with increasing sweetener concentration. Fruit flavors decreased soy aromas, soy flavors, and astringency in yogurts containing soy protein. These results indicate that sweetener concentration and fruit flavors play a crucial role in formulating yogurts fortified with soy protein.
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    Journal of sensory studies 16 (2001), S. 0 
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A two-part study determined the effectiveness of gum-based rinses with or without oil for alleviating residuals of a bitter (0.8 g/L caffeine solution) and an astringent (1g/L alum solution) stimuli in serial responses using a sip and spit method. In Experiment 1, rinsing with deionized water was compared to rinsing with 0.3% xanthan gum in water alone or with 5% corn oil and 0.55% carboxymethyl cellulose (CMC) in water alone or with 5% or 10% corn oil. The 0.3% xanthan gum and 5% corn oil mixture resulted in the highest stimulus intensity difference before and after rinsing, whereas 0.55% CMC had a value of nearly zero for residual effect. Results of a two-alternative forced choice test used in Experiment 2 indicated that both were equally effective for reducing bitterness residuals, but 0.55% CMC solution resulted in the lowest (p=0.007) residual effect for astringency. Therefore, the 0.55% CMC rinse was considered an effective interstimulus rinse to use for assessing both bitterness and astringency in model solutions.
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    Journal of sensory studies 16 (2001), S. 0 
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For discrimination tests not requiring the nature of the difference to be specified in the instructions, such as the triangle, duo-trio and same-different protocols, it is usually assumed that the decision rule used by the subject in order to generate an answer involves the comparison of the relative sensory distances between the samples. However, there is evidence that an alternative cognitive strategy, the β-strategy, involving the absolute categorization of the sensations could be used by the subject when performing these protocols. This paper introduces the characteristics of this alternative strategy by discussing its statistical power (higher than the traditional strategies) and by describing means of investigating which strategy is used by the subject during an experiment as well as illustrating the experimental conditions that might facilitate the use of this particular decision rule.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The perception of astringency and basic taste in mixtures and their interaction effects were investigated by two procedures. In Experiment 1, focused and nonfocused testing procedures were compared using mixtures of low and high concentrations of alum and basic taste solutions. Both procedures yielded taste and astringency intensities that were modality-dependent. Nonfocused testing was used in Experiment 2 to investigate the interactions of astringent phenolic (tannic acid) and nonphenolic (alum) compounds with each basic taste. Sweetness of sucrose increased with increased concentration with or without alum or tannin present. Changes in salty, bitter, and sour taste intensities were modality-dependent. Astringency either remained unchanged or decreased with the addition of sucrose, sodium chloride, citric acid, or caffeine depending upon the taste concentration. Bitterness of tannin and alum at high concentrations was suppressed by the addition of sucrose, sodium chloride, or citric acid; sourness also decreased in the presence of sucrose or sodium chloride as well as a high level of caffeine.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Principal component similarity (PCS) analysis was used to evaluate judge performance from a wine competition. Data were analyzed for five international judges and seven wine makers, for 42 white, 30 red and 25 specialty wines, using a 20-point quality scoring system. Principal similarity plots were used to group judges according to judging 'style’ and to identify outliers, for each wine category. Judge groupings were consistent when three different references were used; however, the most interpretable PCS plot was obtained when the overall mean-judge-score was used as the reference. Results from PCS were compared to principal component analysis (PCA). PCS analysis allowed the information from all significant principal components to be graphically represented in two dimensions and was more successful in classifying judges than plots based on the first three principal components. The technique of PCS is an important complement to existing methodologies, and can provide wine competition coordinators with an objective technique for judge evaluation and selection.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Exact tables calculated directly from the probability function of a beta-binomial distribution are provided for replicated difference and preference tests. The tables can be used for small experiments when the numbers of replications and trials are not more than five.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dependence among responses in using the A-Not A or “ Yes-No” task are accounted for in new hypothesis testing models. The new models involve adjustments to Pearson's and McNemar's chi-square statistics and to the variance of d', a measure of signal detectability or sensitivity.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Anecdotal evidence suggests that astronauts’ perceptions of foods in space flight may differ from their perceptions of the same foods on Earth. Fluid shifts toward the head experienced in space may alter the astronauts’ sensitivity to odors and tastes, producing altered perceptions. Our objective was to determine whether head-down bed rest, which produces similar fluid shifts, would produce changes in sensitivity to taste, odor or trigeminal sensations. Six subjects were tested three times prior to bed rest, three times during bed rest and two times after bed rest to determine their threshold sensitivity to the odors isoamylbutyrate and menthone, the tastants sucrose, sodium chloride, citric acid, quinine and monosodium glutamate, and to capsaicin. Thresholds were measured using a modified staircase procedure. Self-reported congestion was also recorded at each test time. Thresholds for monosodium glutamate where slightly higher during bed rest. None of the other thresholds were altered by bed rest.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of liking, brand and price label on purchase intention were studied on crisp snacks in branded, supermarket own label and economy form. Unlabeled assessment segregated the products into differing levels of liking which did not correspond to marketed price and brand location. Level of liking dominated purchase intention under partial label (price or brand alone) and full label (price with brand) conditions. Relative and derived purchase intention measures gave clearer label effects with significance for brand and price. Consumers who professed higher price awareness were more influenced by price, but those professing brand as a main purchase intention reason gave more weight to liking. Results from analysis of purchase intention and degree of liking measures according to private body conscious level were inconclusive.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Forty pure chemical compounds representing a wide range of odors, were evaluated by a panel of 240 consumers. These compounds were matched with a list of 40 common descriptors. The results were analyzed by Correspondence Analysis and Hierarchical Clustering. This original approach enhanced the study by providing a layman's point of view and thereby shedding light on the theories of olfactory perception. The level of odor confusion by consumers was also studied. Consumers pointed out three principal odorant directions which we called “ citrus”, “ sweet” and “ heavy” . Aniseed and garlic odors were the most isolated notes. The association among compounds or odors was explained by semantic processes and by the odorant products consumers used which make up their odorant domain.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a set of analyses on sensory directional attributes used to rate experimentally designed pizza products. Consumers may or may not know the ‘optimal’ sensory level of attributes for pizza, so that the usefulness of the sensory directional varies by attribute. Furthermore, the sensory magnitude of each sensory directional attribute varies, as shown by the slope (B) relating the two attributes (Sensory Magnitude = A + B (Directional Rating)). The study incorporated sensory directionals into evaluation of products varied according to an experimental design. The optimal product emerging from the design does not necessarily exhibit a sensory directional profile where all attributes are ‘on target’, nor does a product whose sensory attributes are all on ‘target’ exhibit the highest level of liking.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cluster analysis, consonance analysis, principal component analysis (PCA) and the GRAPES program (Schlich 1994) were compared for the evaluation of panel performance. Ten judges evaluated 25 Merlot wines for 24 color, aroma and flavor attributes. Cluster analysis grouped similar judges. PCA identified judges according to their attribute use. Consonance analysis determined a numerical index for attribute agreement and the GRAPES program compared judges in their use of the scale, reliability, discrimination and disagreement. Three of the four techniques provided a graphical representation of similarities and differences between judges. Methodologies were best used in conjunction with one another. Ultimately the application of these tools will serve to improve the quality of sensory evaluations.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study examines the effect of beer assessment training on verbal and nonverbal performance. Two groups of subjects are asked to sort, match, and describe a set of 12 beers (6 supplemented and 6 commercial beers). Subjects from the first group are enrolled in a beer-training program. Subjects in the second group are untrained beer consumers. Results show that although both groups perform the matching task equally well, trained subjects performed better on supplemented beers and untrained subjects on commercial beers. Examination of the generated vocabulary shows that 44% of the terms are common to trained and untrained subjects. However, an analysis of the terms’ efficiency shows that whereas for trained subjects, precise terms are more efficient than intensity or hedonic terms; the opposite is observed for untrained subjects. This suggests that it is not the term itself that is important but the common reference associated to it.
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    Notes: Quantifying flavor in fruit concentrates for use in soft drink manufacture remains a technical problem. To explore sensory quantifications, a comparison between descriptive analysis (free choice profiling) and ratio scaling strategies was effected. This employed 20 assessors, and a range of commercial black-currant drinks and model product formulations. Free choice profiling yielded product clusters in commercial drinks, but not for formulated drinks. Few descriptors were significant in discriminating samples of the latter group. In addition, assessors were not consistent in quantifying attributes. In contrast, magnitude estimation of the single attribute, overall flavor intensity, produced data which after statistical treatment showed that assessors were able to resolve differences clearly. It was concluded ratio scaling of a single complex attribute had provided a better quantification of flavor character than line scaling of multiple simple attributes.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In 2 separate studies, 6 rice and 6 dry-cured ham samples were tasted by 2 sets of consumers. The consumers were asked about their hedonic evaluation and invited to comment on the weak and strong points of food samples. The frequencies of quoted terms were analyzed by correspondence analysis (CA). A trained panel carried out the sample profiles. Hedonic scores were linked to objective assessment using the preference mapping (PM). Figures from CA and PM showed similar proximity between samples in both studies. The descriptive vocabulary used by trained assessors and consumers contained both similarities and differences. In the rice study, the trained panel described Basmati with the terms ‘little elastic’, ‘long grain’ and ‘brioche flavor’, while consumers used ‘aromatic’, ‘long grain’, ‘white color’ and ‘good texture’. In the dry-cured ham study, Iberian and Corsican samples were described by ‘rancid’, ‘blue cheese’, ‘mushroom’, ‘bitter’ and 'sweet’ attributes while consumers only used ‘too fatty’, ‘bad taste’ and 'strange’ terms. Trained assessors stressed the greatest sensory differences while consumers focused on salient popular and unpopular traits. Weak/strong points analysis was efficient to show the level of acceptability by the number of strong points attributed to the samples and the main reasons for acceptability or rejection.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The change in flavor produced by food and wine interactions was explored using descriptive analysis of Hollandaise sauce prepared with two levels of butter and three wines: a Chardonnay which was unoaked, acidified with 1.5 g/L citric acid or aged in oak for one year. To measure the effect of the sauce on wine flavor, the intensity of citrus, buttery, and toasted flavor by mouth and of sourness and bitterness was rated in each wine before and after each sauce was tasted. In a second testing series, lemon, brothy and creamy-butter flavor by mouth and creamy mouthfeel were rated for each sauce before and after tasting each wine. The effect of Hollandaise sauce on wine flavor was greater than the effect of wines on sauce flavor, with the higher fat sauce having a slightly larger effect overall. Sour and bitter flavors of the wines decreased in intensity after Hollandaise sauce was tasted, while the buttery flavor by mouth increased. The toasted flavor decreased significantly in the oaked wine after the sauce had been tasted, while citrus flavor was decreased only for the unoaked wine.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The suitability of stevioside as a sweetener in peach juice was investigated. Comparison between stevioside and sucrose in terms of sweetness, sweet and bitter aftertastes were determined both in water and peach juice. The results demonstrated that 160 mg/L of stevioside may replace 34 g/L of sucrose in juice, with a 25% decrease in calories, without affecting the sensory characteristics of the product. Synergistic and inhibitory effects between sucrose and stevioside were also monitored at different stevioside concentration. A new juice formulation sweetened with a binary mixture of stevioside (160 mg/L) and sucrose (56 g/L) was not significantly different in terms of desirability from a reference product sweetened with 9% sucrose.
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  • 58
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Visual haze detection thresholds were assessed in thirty panelists by two methods: the ascending method of limits and a transformed staircase procedure (UDTR, from Wetherill and Levitt 1965). The 3AFC test was used as the response procedure for both methods. Experimental samples consisted of an apple juice simulation (water with food coloring). Haze was added to the samples using formazin, and was calibrated to eleven levels ranging from 0.75–13.30NTU. Haze detection thresholds under store-like conditions (3.55 ± 0.57 [mean ± S.E.] and 3.16 ± 0.50 NTU by the two methods, respectively) were higher than those found previously under more controlled viewing conditions. No differences were found between methods, genders, or order of method presentation (p 〉 0.05); a practice effect showed a slight improvement in detection thresholds between sessions (p= 0.05). Nonparametric tests confirmed the similarities in the threshold estimates from the two methods. The two methods estimated visual haze detection thresholds equally well. However, the ascending method of limits may be preferred method due to the shorter time involved in administration.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Diverse food choices and preferences are commonly observed between consumers cross-culturally, however, many aspects of these behavioral differences are not yet fully understood. In order to investigate cross-cultural texture preferences, six extruded snack samples, manufactured under different processing conditions to represent a range of textural characteristics were characterized by a trained panel using descriptive sensory analysis. In parallel, thirty-eight naive European-Origin and thirty-seven naive Chinese-Origin Australian consumers (t = 75) rated their preference for the snacks. The snacks were not representative of any snacks on the market and thus represented a “ novel” product in both cultures. Additionally, consumers answered a simple questionnaire and completed the food neophobia scale. Results of descriptive analysis indicated significant differences (p≤0.01) between the samples for 13 out of 15 descriptive attributes but no significant differences in preference were found between European-origin and Chinese-origin consumers. However, overall analysis of mean effects indicated that Chinese-origin consumers rated samples significantly higher than European-origin consumers (p≤0.05), suggesting a cultural bias in the use of line scales. Gender did not influence texture preference, however, age significantly influenced preference for three of the samples (p≤0.05) and analysis of mean effects also indicated differences in consumers’ ratings which were related to age. Food neophobia classification did not influence preference, although many more Chinese-origin consumers (28) were classified as neophobic than were European-origin consumers (11).
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Although expert assessment of food characteristics is recognized as a key step in product development, the use of consumer based measurements is sometimes recommended as an equivalent to the experts. From cognitive psychology, support of the role of perceptual learning is found in some instances, although this could not be relevant in others. To address this point performance analysis of experts and untrained panelists in cheese texture evaluation was carried out. Neither the untrained panelists nor the experts were familiar with either the scales or the kind of cheese. The same Cheddar cheese was given to 44 untrained subjects in three trials to assess hardness. The results showed that their judgment has a 29% average random error variance; the interrater reliability being low. The same experiment gave a random error variance of 2% for three highly skilled judges (experts). The difference in variance was linked to training. Untrained panelists also showed an adaptation error. Nevertheless, there was no significant difference between the average ratings of both groups, whether untrained or experts.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Previous experiments have shown that the same-different test, because of its more suitable cognitive strategy and lower memory requirements, is a more powerful and sensitive alternative to the triangle and duo-trio tests. This project describes an experiment conducted in order to investigate ways to improve further the performance of the same-different test. Three protocols were compared using orange flavored beverages and 24 judges: the same-different method, the triangle test and the dual-pair paradigm. The latter protocol could improve the same-different's performance by preventing the spontaneous variations of the judges’τ criterion. While no significant differences were detected among the d’ values obtained with each procedure, a trend was observed for the same-different and dual-pair test to be slightly more sensitive (higher d’ values) than the triangle test. Since the same-different test is statistically more powerful, it is a preferable choice over the triangle, duo-trio and dual-pair tests.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The most widely used scale for assessing food liking or disliking is the 9-pt hedonic scale. Unfortunately, this affective scale suffers from problems related to unequal scale intervals and the underuse of end categories, which results in a reduced ability to differentiate among extremely well liked or extremely disliked foods. Magnitude estimation avoids these problems while enabling ratio statements to be made about the data. However, it does not provide absolute ratings of liking/disliking and can be difficult for some consumers to use. We report here on the development of a labeled affective magnitude scale (LAM) scale that has advantages over both the 9-pt hedonic scale and magnitude estimation. Forty-four semantic labels were scaled for their affective meaning by subjects using modulus-free magnitude estimation. The geometric mean magnitude estimates obtained for each semantic label were used to construct a series of labeled affective magnitude scales by spacing the labels along a visual analogue scale according to their obtained semantic values. Reliability and sensitivity studies were conducted to assess the effects of alternative semantic and numeric labels. The results of these studies led to the choice of a scale format that uses verbal labels that are consistent with the 9-pt hedonic scale. The labeled affective magnitude (LAM) scale was compared to the hedonic scale and magnitude estimation in several food preference and acceptability tests. The LAM was shown to have equal reliability and sensitivity to the hedonic scale, provided somewhat greater discrimination among highly liked foods, and resulted in data that were similar to magnitude estimation in terms of the obtained ratios among rated stimuli. The LAM scale was also judged by consumers to be as easy to use as the 9-pt hedonic scale and significantly less difficult than magnitude estimation.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Contextual shifts were observed for sweetness of a fruit beverage and for estimated tactile roughness of sandpapers. Midrange stimuli were judged to be less intense in the context of stronger items and more intense in the context of weaker items, a contrast effect. The use of a reference standard decreased the size of the contrast shift for the labeled magnitude scale but not for magnitude estimation.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stimulus frequency context effects were noted for stimuli with positive, negative and no skew, using aqueous NaCl stimuli of different concentrations as a model system and orange juice stimuli with added amounts of sucrose as a beverage system. The hypothesis that analysis by signal detection Δm values, rather than individually rated intensity values, would result in the absence of the context effect, was not confirmed.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: R-index measures were obtained from judges who ranked black coffees for preferred drinking temperature. Preferred temperatures were above thermal pain and thermal damage thresholds. The least preferred temperature was below the oral thermal pain threshold. Similar results were obtained with a ranking for temperatures that judges felt were most likely to be served in a coffee shop. Observations of customers in coffee shops indicated that they began sipping coffee at similar high temperatures.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a previous paper Kunert and Qannari (1999) discussed a simple alternative to Generalized Procrustes Analysis to analyze data derived from a sensory profiling study. After simple pretreatments of the individual data matrices, they propose to merge the data sets together and undergo Principal Components Analysis of the matrix thus formed. On the basis of two data sets, it was shown that the results slightly differ from those obtained by means of Generalized Procrustes Analysis.In this paper we give a mathematical justification to this approach by relating it to a statistical regression model. Furthermore, we obtain additional information from this method concerning the dimensions used by the assessors as well as the contribution of each assessor to the determination of these dimensions. This information may be useful to characterize the performance of the assessors and single out those assessors who downweight or overweight some dimensions. In particular, those assessors who overweight the last dimensions should arouse suspicion regarding their performance as, in general, the last dimensions in a principal components analysis are deemed to reflect random fluctuations.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The “ A” - “ Not A” method is a rating method with two categories. It is often treated as a discrimination method. Unlike forced choice procedures, the Thurstonian model for this method involves a choice criterion. In statistical tests, it is treated as a comparison of two proportions. In this paper, the power for hypothesis tests involving the monadic and replicated monadic “ A” - “ Not A” method is discussed. The power functions and the sample sizes needed for 80% power are given based on Thurstone's δ. Designs with equal and unequal allocations for A and A (Not A) samples are considered. The power of the method is also compared with that of four forced choice methods under the assumption that the perceptual variance is identical among methods. The comparison shows that, in general, the power for the five methods ranks from high to low: the 3-AFC, 2-AFC, “ A” - “ Not A”, triangular and duo-trio. The comparison also shows that, based on the same number of panelists and/or the same sample size for the A and A− samples for the methods, if the panelists are not too discrepant and the choice criterion in the “ A” - “ Not A” method is not too strict or too lax, the power of the “ A” - “ Not A” method is very close to that of the 2-AFC method.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liking is a key measure for applied product development. All too often, however, the liking attributes are simply reported, but other than analyzing overall liking ratings no other analysis is done on the ratings. Much more remains for applied product testers to learn from these liking attributes. This paper presents a detailed analysis of the interrelations among different liking attributes for apple pie. It shows that panelists discriminate among samples using different liking scales, but many of these scales correlate with each other creating a great deal of redundancy in the list of attributes. Factor analysis reveals one major dimension for liking of the entire pie, and three dimensions for liking of slices. A different way of analysis shows potentially more utility for developers. A linear model relating overall liking to each attribute liking reveals different slopes, suggesting different importance levels for the attribute liking scales. Furthermore, one can create an integrated liking model. The liking ratings can be combined into a single, overall product model, allowing the researcher to understand how changes in one liking attribute simultaneously affect all other liking attributes.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aim of this work was to develop a vocabulary to describe the odors of selected distilled beverages in 12 panel hours, by monitoring the performance of each assessor and of the panel throughout vocabulary development. Sixteen assessors initially produced a vocabulary of 30 odor terms during group discussion. This list was modified to 20 attributes, and panel agreement on its definition was monitored, over three sessions of descriptive analyses of eight samples which could represent the diversity of odors to be encountered in future use of the vocabulary. The data from each descriptive analysis was analyzed by Principal Component Analysis, Analysis of Variance, Spearman correlation and Kendall W Test. Results obtained after each descriptive analysis were shown to the assessors and discussed. Results obtained over the three sessions showed sufficient improvement in the assessor's performance to deem the panel competent for descriptive analysis of the distilled beverages studied.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sensory evaluation data is sometimes collected using trinary category scales. Nonparametric data analysis for such data is discussed and a homogeneity statistic for trinary data is proposed which is simple enough to calculate with a pocket calculator. A statistic for identifying market segmentation in trinary data is also suggested.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An alternative method for measuring response and analyzing data in consumer research was explored in this study which attempted to identify critical flavor properties of mango. Twelve mango samples were evaluated according to 13 flavor descriptors by a trained panel using 150-mm unstructured lines. Consumers (n = 120), intercepted in supermarkets, each tasted 3 samples and responded ‘yes’ or ‘no’ to an intent-to-purchase question. Consumer response, coded by respectively assigning 0 or 1 to each negative or positive answer, was expressed as a probability of purchase and related to descriptive attributes using logistic regression. Critical descriptors were peachy, grassy, and green banana (α= 0.10). The function generated had an index of discrimination of 0.70. Although limitations in flavor variations and possible segmentation among the consumers studied restricted the usefulness of the acceptability function, using a probability of purchase as an index of acceptability and logistic regression to relate consumer response with product attributes was demonstrated.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Eleven samples of strawberry yogurt prepared with different red color concentrations using Ponceau 4R (E-124) were evaluated by instrumental and sensory methods. Color intensity evaluation was carried out by a panel of eight assessors specifically trained to measure strawberry color in yogurt. Color acceptability was measured with 120 regular and frequent consumers of yogurt. Color was measured with a Minolta Chroma Meter CR-200b, obtaining parameters L*, a* and b*. Principal component analysis was performed on the instrumental variables. Regression models between the instrumental first principal component, red color concentration, sensory intensity, and acceptability allowed determining quality control limits for red color attribute. These limits may be controlled by selecting either instrumental or sensory methods, being the latter easy to implement and providing dependable results.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a study of the attributes of margarine, showing the depth of information about consumer perceptions and drivers of liking that emerges from a detailed analysis of relations among attributes. The paper develops three sets of analyses to understand relations among attributes: principal components analysis in order to identify basic dimensions of perception, linear functions relating overall liking to attribute liking or to image ratings in order to identify drivers of liking, and quadratic functions that relate overall liking or image ratings to sensory attribute levels in order to identify optimal sensory levels and to create sensory preference segments. The analyses show how consumer data can generate learning about the consumer perceptions on the one hand, and guidance for product development.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Twenty-one rice samples covering examples of aromatic, long and medium grain, instant, and parboiled products were evaluated by a group of 120 Asian consumers, currently living in the United States and by a professionally trained sensory panel. Results showed that imported Thai Jasmine rice was preferred by this group of Asian consumers over every other rice tested including domestically grown Jasmine rice. The most important acceptance factors for Asian consumers were cooked rice appearance and aroma. Predictive models of rice overall acceptance were evaluated using descriptive sensory evaluation data (i.e. including appearance, flavor and texture attributes). These models allowed the identification of sensory characteristics most important to rice acceptance by this consumer group. This information could be useful to rice breeders to select for specific sensory characteristics expected by Asian consumers.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper analyzes the results of different strategies for selecting test products in category appraisals. The three strategies are random selection of products from the marketplace, selection on the basis of consumer sensory data, and selection on the basis of expert panel data. All three methods generate stable results for category appraisals. The stability of the results (e.g., in terms of ‘drivers of liking’) increases very quickly and then levels off, suggesting that the researcher does not have to work with a particularly large number of products in a category appraisal to understand the sensory-liking dynamics.It appears in our case, that 18 products were an appropriate number to strongly reflect results for 50 products. Researchers need to be sensitive to the variation in each category. Some categories may require more or less than this number of products to cover all the sensory ranges within the specific category.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Manchego cheese is a high-fat pressed ewe's-milk cheese made in Castilla-La Mancha (Spain) and produced by enzymatic coagulation. The minimum ripening time before marketing required by the Regulatory Board of the Manchego Cheese Appellation of Origin is 60 days.This paper describes the physicochemical, proteolysis, sensory and texture characteristics of Manchego cheese, and the degree of homogeneity of cheeses made under the Manchego Appellation of Origin. The data gathered in this study indicate that sensory and instrumental analysis are useful tools for detecting changes in Manchego cheese during ripening. These changes were first detected by the instrumental analysis (2 months). The panelists detected differences after 4 months’ ripening in all the factories. With physicochemical analysis, on the other hand, longer ripening times (6–8 months) are required before such changes become appreciated.
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    Notes: This research characterized the time-intensity (TI) profiles of monosodium glutamate (MSG), disodium 5′-inosinate (IMP), and disodium 5′-guanylate (GMP). Twenty subjects rated total taste intensity of single solutions of 2.5, 5 and 10 mM MSG, 0.63 and 2.5 mM IMP and GMP, and some of their mixtures, using the TI method. The profiles generated were atypical of other taste modalities. Time to maximum intensity waslong (16–20s), followed by a plateau at maximum intensity, and a persistent aftertaste (50–96s duration). Maximum intensities of the samples varied (p 〈 0.001), with mixtures of 10 and 5 mM MSG with 2.5 mM IMP or GMP yielding the highest intensities. Similar differences were found for total duration and area under the curve. These results indicate that flavor potentiators may increase total flavor during consumption. Synergism between flavor potentiators was demonstrated.
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    Notes: Different goat cheeses from Chile were studied by Free-Choice Profile (FCP) analysis. Generalized Procrustes Analysis (GPA) applied to FCP data permitted differentiation between samples and informed on the attributes responsible for the observed differences. Appearance was a dominant factor in discriminating samples and to a lesser degree textural variables were also correlated with GPA dimensions. In acceptability the fresh cheeses were significantly preferred over the ripened ones.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: The present paper shows that the techniques developed and exploited by qualified geophysicists have brought high sensitivity magnetic surveys to an industrial stage.It will appear that for most mining and oil problems, either on land or sea, the necessary modern equipment already exists without developing it further in the future. In particular, the digitalization of data is practically finished for the magnetometer itself as well as for some navigation techniques.
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    Topics: Geosciences , Physics
    Notes: Simultaneous measurements made on an ice island and about 1000 ft. below show that magnetic anomalies can be detected in the presence of large time variations of the magnetic field. Attenuation and phase lag of time variations at depth are measurable but do not limit the utilization of the vertical gradient of geomagnetic total intensity for defining crustal anomalies.
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    Geophysical prospecting 15 (1967), S. 0 
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    Topics: Geosciences , Physics
    Notes: As shown previously [50], the relations between formation factor, permeability, and porosity can be expressed in statistical parameters of the microscopic pore system. A number of other macroscopically measurable quantities depend on those same parameters. Thus, by proper combination of these quantities, it should be possible to solve for those parameters, that cannot be retrieved by direct methods. In this article, the dependencies on these statistical parameters of the capillarity with imbibition and drainage, the irreducible water saturation, the flow dispersion with miscible displacement, and quantities that are directly observable at ground surfaces or thin sections, are preliminarily studied as a preparation for possible practical measurements.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
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    Topics: Geosciences , Physics
    Notes: A system of geophysical units is proposed which is based on the International System of Units, using the meter, the kilogram, the second and the ampere as fundamental units. A historical introduction is given and the reasons for preferring the use of the International System of Units in exploration geophysics, are explained.At the meeting of the European Association of Exploration Geophysicists at Stockholm a resolution will be proposed recommending the use in exploration geophysics of the International System of Units.
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    Topics: Geosciences , Physics
    Notes: A two dimensional linear filter operator based on Strakhov's method for the extraction of a potential field signal (gravity or magnetic) from a background of homogeneous random noise has been developed. An algorithm to solve for the coefficients of the operator is given together with the corresponding computer program in FORTRAN language. It may be used on any machine using FORTRAN IV. A few examples of the operator are also included.
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    Geophysical prospecting 15 (1967), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The design of least-squares optimum filters is based upon minimizing a suitably defined error criterion. The expected value of this error is easily computable after the coefficients of the filter have been determined.When a particular filtering problem is specified, there are several parameters which are specifically not included in the optimization procedure. However, the magnitude of the expected error may be quite sensitive to these parameters. The examination of the relative values of the expected error for variations of these unspecified parameters may lead to a better definition of the filter problem.The parameters which are left unspecified by the general least-square filter definition include:1. The addition of white noise to the signal autocorrelation to stabilize the filter behavior.2. The specification of the shape of the desired output of the filter.3. The specification of the lag between the desired output and the input.Examples are given showing the relationship between these parameters and the value of the expected error.
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    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
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    Physics Letters B 317 (1993), S. 474-484 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
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    Meteorology and atmospheric physics 16 (1967), S. 169-180 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Summary On the basis of a spring blocking-situation, which lasted for 16 days (March 2 to 18, 1955), the author studied the dynamic processes in building up and maintaining of a blocking-situation. Whereas during the preceding period of the blocking a northward transport of angular momentum of the air had occurred, during the blocking itself the angular momentum is transported southward. Besides, the author has analyzed thoroughly the development phases of 25 blockings, which had occurred in a period of eight years, and gives a table with the most important results.
    Abstract: Résumé On étudie ici les phénomènes dynamiques qui se produisent lors de l'établissement et du maintien d'une situation de blocage. Pour ce faire, on se sert d'une situation de printemps qui a duré 16 jours (du 2 au 18 mars 1955). Pendant la période précédent le blocage, on constate un déplacement vers le nord du moment de rotation absolu de la vitesse de l'air. Pendant la période de blocage elle-même, le moment de rotation absolu se décale au contraire vers le sud. On analyse en outre très exactement l'évolution de 25 cas de blocage répartis sur 8 ans. Les résultats les plus importants de cette analyse sont rapportés sous forme de tables.
    Notes: Zusammenfassung An Hand einer 16tägigen Frühjahrblockingsituation (2. 3. bis 18. 3. 1955) wurden die dynamischen Vorgänge bei der Bildung und Aufrechterhaltung der Blockinglage studiert. Während in der Vorperiode des Blockings ein Nordwärtstransport von absolutem Rotationsmoment der Geschwindigkeit der Luft stattfindet, wird während der Blockingsituation selbst das absolute Rotationsmoment nach Süden verfrachtet. Weiters wurden die Entwicklungsvorgänge von 25 Blockingfällen während eines Zeitraumes von acht Jahren genau analysiert und die wichtigsten Ergebnisse tabellarisch zusammengestellt.
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    Meteorology and atmospheric physics 16 (1967), S. 181-211 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Summary Based on 21 571 daily upper wind measurements the authors derive the dependences on altitude of the scalar and vector means of the wind speed, of the zonal and meridional components, of the mean resultant wind and of the constancy of the wind up to 30 km above Vienna for each month and also the annual variation of the wind speed and of the frequency distributions of the wind directions for the various levels. The peculiarities are thoroughly discussed and explanations could be given for most of them. One finds out that, during the transitional seasons, the upper winds show a remarkable behaviour in some months, which cannot be explained easily. The annual variations of the scalar as well as of the vectorial mean wind speeds present double-waves even in the troposphere, apart of the lowest levels. Partly, the extremes of these double-waves in the upper troposphere, are inverse to those in the lower stratosphere. At altitudes above 18 km the transition from the winter westerlies to the summer easterlies in spring advances only gradually from the larger heights to the lower ones, however, the reverse transition occurs very sharply with the change from August to September. Therefore, in investigations of the upper winds, it is very necessary to use the data of the single months separately as in seasonal combinations some essential characteristics are obscured.
    Abstract: Résumé Partant de 21 571 mesures journalières du vent en altitude, mesures effectuées à Vienne (Autriche), les auteurs discutent et cherchent à expliquer les particularités de cet élément météorologique. Pour ce faire, ils ont établi pour chaque mois la variation de la valeur scalaire et vectorielle de la vitesse du vent, ses composantes zonale et méridienne, la translation de l'air qui en résulte, la persistance du vent avec l'altitude jusqu'à 30 km ainsi que la variation annuelle de la vitesse du vent et la répartition des fréquences de sa direction aux différents niveaux. Il en découle que, durant les périodes de transition entre les saisons, les conditions de vent en altitude présentent un comportement particulier au quelques mois, ce qui n'est pas facile à expliquer. La variation annuelle des valeurs scalaires et vectorielles de la vitesse du vent présentent, abstraction faite des couches voisines du sol, mais dans la troposphère déjà, des ondulations doubles dont les extrêmes sont opposés, dans la troposphère supérieure, à ceux de la basse stratosphère. Aux altitudes supérieures à 18 km, le changement des courants d'ouest, dominent durant l'hiver, à ceux d'est qui se rencontrent en été se fait progressivement au printemps des couches les plus élevées vers les plus basses. Le phénomène inverse se produit par contre brusquement d'août à septembre. Il est par conséquent indispensable, dans les recherches des conditions de vent en altitude, de considérer les mois individuellement, car un groupement par saison en estomperait les caractéristiques principales.
    Notes: Zusammenfassung Aus 21 571 täglichen Höhenwindmessungen werden für jeden Monat die Änderungen der skalaren und der vektoriellen Mittelwerte der Windgeschwindigkeit, der zonalen und der meridionalen Komponenten der Windgeschwindigkeit, der resultierenden Luftversetzung und der Beständigkeit des Windes mit der Höhe bis 30 km über Wien sowie der Jahresgang der Windgeschwindigkeit und der Häufigkeitsverteilung der Windrichtungen für die verschiedenen Höhenstufen abgeleitet und in ihren Besonderheiten eingehend diskutiert und zu erklären versucht. Dabei ergibt sich, daß in den Übergangsjahreszeiten die Höhenwindverhältnisse in einzelnen Monaten ein auffallendes Verhalten zeigen, das nicht einfach zu erklären ist. Die Jahresgänge der skalaren wie auch der vektoriellen Geschwindigkeitswerte weisen auch, abgesehen von den bodennahen Schichten, bereits in der Troposphäre Doppelwellen auf, deren Extreme in der oberen Troposphäre zum Teil den Extremen in der unteren Stratosphäre entgegengesetzt sind. In Höhen über 18 km erfolgt der Übergang von der im Winter vorherrschenden westlichen Strömung zum sommerlichen Ostwind im Frühling allmählich von den höchsten Schichten nach unten fortschreitend, der umgekehrte Übergang vom August zum September dagegen sehr scharf. Es ist daher notwendig, bei Untersuchungen der Höhenwindverhältnisse die einzelnen Monate besonders in Betracht zu ziehen, da bei einer Zusammenfassung nach Jahreszeiten wesentliche Merkmale verwischt werden.
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    Meteorology and atmospheric physics 16 (1967), S. 242-259 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Die Wärmebilanzgleichung für die Unterseite von schwimmendem Meereis wird an Hand von Beobachtungen der Eistemperatur, der Wassertemperatur, der Strömungsgeschwindigkeit und der Eisdickenänderung ausgewertet. Unter der Annahme gleicher Austauschkoeffizienten für Bewegungsgröße, Wärme und Salzgehalt (im Mittel 24 cm2 sec−1) ergibt sich für die ozeanische Grenzschicht ein außerordentlich kleiner Gradient der Wassertemperatur (durchschnittlich zwischen 2.10−5 und 4.10−4°C/Meter), der durch direkte Beobachtungen schwer nachzuweisen ist. Es ist zu vermuten, daß ein beträchtlicher Teil der Wärmeabgabe von der relativ warmen atlantischen Wassermasse an die arktische Atmosphäre durch Öffnungen in der Meereisdecke erfolgt.
    Abstract: Résumé On établit l'équation du bilan thermique valable pour la surface inférieure de la glace marine dérivante. Pour ce faire, on se sert d'observations de la température de la glace, de celle de l'eau, de la vitesse du courant et des variations de l'épaisseur de la glace. En admettant que les coefficients d'échange sont les mêmes pour la quantité de mouvement, la chaleur et le taux de salinité (en moyenne 24 cm2 sec−1), il résulte pour la couche limite un gradient extrêmement faible de la température de l'eau (situé en moyenne entre 2·10−5 et 4·10−4°C/m); un tel gradient est difficile à prouver au moyen d'observations directes. On peut supposer qu'une partie importante de la chaleur transmise par l'eau relativement chaude de l'Atlantique à l'atmosphère arctique passe au travers des lacunes de la couche de glace recouvrant l'océan.
    Notes: Summary The heat balance equation for the bottom surface of floating sea ice is evaluated on the basis of observations of ice temperature, water temperature, current velocity, and ablation or accretion of ice. Assuming equality of the eddy diffusivities for momentum, heat, and salt (average 24 cm2 sec−1) it is shown that the temperature gradient in the oceanic boundary layer is extremely small (averages between 2.10−5 and 4.10−4°C/meter) and difficult to measure directly. It is suggested that a large part of the heat transfer from the relatively warm Atlantic water to the arctic atmosphere may occur through open leads in the ice cover.
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    Meteorology and atmospheric physics 16 (1967), S. 260-266 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Summary In this investigation the anomaly-effect on the ionosphericE-layer critical frequency (ordinary component,f 0 E), which is observed frequently during the forenoon hours, has been calculated for 80 selected diurnal variations on simplified conditions. The received results are compared with Appleton's theory.
    Abstract: Résumé L'effet du retardement de la fréquence critique de la couche-E ionospherique (composante ordinaire,f 0 E) qu'on peut observer souvent durant les heures avant midi, est examiné pour 80 enregistrements diurnes á conditions simplifiées. Les résultats reçus sont comparés avec la théorie d'Appleton.
    Notes: Zusammenfassung Der zeitliche Verlauf der Vormittags-Anomalie in den Tagesgängen der kritischen Frequenzen der normalenE-Schicht (Verlangsamung des Anstieges der Elektronendichte kurz vor dem Ortsmittag im Vergleich zur Chapman-Schicht) wurde unter vereinfachten Voraussetzungen für 80 ausgewählte Tagesgänge des Jahres 1958 berechnet. Die erhaltenen Ergebnisse werden mit der Appletonschen Theorie verglichen.
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    Meteorology and atmospheric physics 16 (1967), S. 301-313 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Summary The position, direction and speed of the high-tropospheric jet-streams in the years 1955 to 1963 were determined from the 300 mb chart of the Daily Weather Map of the German Weather Service. The seasonal variations of the positions, intensities and directions of the polarfront jet (PFJ) and subtropic jet (STJ) in the region between 20° W and 20° E and between 35° N and 70° N have been evaluated and are discussed here.
    Abstract: Résumé En partant des cartes journalières de la surface de 300 mb éditées par le service météorologique de la République fédérale d'Allemagne, on a déterminé la position, la direction et la vitesse des courants “jets” de la troposphère supérieure et cela pour la période 1955 à 1963. On indique et on discute les variations saisonnières de la position, de l'intensité et de la direction du “jet” accompagnant le front polaire (PFJ) et du “Jet” subtropical (STJ). La zone étudiée s'étend entre le 20ème méridien E et le 20ème méridien W, respectivement entre les 35ème et 70ème paralèlles N.
    Notes: Zusammenfassung Aus der 300mb-Fläche der täglichen Wetterkarte des deutschen Wetterdienstes wurden für den Zeitraum von 1955 bis 1963 Lage, Richtung und Geschwindigkeit der hochtroposphärischen Strahlströme bestimmt. Die jahreszeitlichen Änderungen der Positionen, Intensitäten und Richtungen des Polarfront-Jet (PFJ) und des Subtropen-Jet (STJ) werden für den Bereich von 20° W bis 20° E und von 35° N bis 70° N angegeben und diskutiert.
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    Meteorology and atmospheric physics 16 (1967), S. 314-320 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Summary The variations of the total ozone amount at ten european stations were correlated in couples. The correlation coefficients decrease exponentially with increasing distance of the stations. From this exponential law the mean extension of low stratospheric air-parcels was determined to be 670 km. On computing the correlation coefficients a time shift was observed which demonstrates the predominantly zonal west east ozone transport.
    Abstract: Résumé On a établi les corrélations des variations de l'ozone total relevé à 10 stations enropéennes prises deux par deux. Les coefficients de corrélation qui en résultent sont, en moyenne, en relation exponentielle avec la distance séparant les stations. De cette diminution, on a estimé à 670 km l'étendue moyenne des gouttes d'air stratosphériques. Un décalage dans le temps, lors du calcul des coefficients de corrélation, montre clairement le transport généralement zonal de l'ozone de l'ouest vers l'est.
    Notes: Zusammenfassung Die Variationen des Gesamtozonbetrages an zehn europäischen Stationen wurden paarweise korreliert. Die Korrelationskoeffizienten fallen im Mittel exponentiell mit der Entfernung der Stationen ab. Aus diesem Abfall wurde die mittlere Ausdehnung stratosphärischer Luftpakete mit 670 km abgeschätzt. Eine zeitliche Verschiebung bei der Berechnung der Korrelationskoeffizienten veranschaulicht den vorwiegend zonalen West-Ost-Ozontransport.
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    Meteorology and atmospheric physics 16 (1967), S. 382-388 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
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    Meteorology and atmospheric physics 1 (1949), S. 347-357 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Ein Luftpartikelchen, das ausschließlich adiabatischen Zustandsänderungen unterliegt, nimmt seine Gleichgewichtslage im Innern einer im hydrostatischen Gleichgewicht befindlichen Luftmasse ein, wenn die SummeS seiner spezifischen Enthalpie und seiner potentiellen Energie in der Masseneinheit ein Extrem wird; je nachdem dieses Extrem ein Minimum oder ein Maximum ist, ist das hydrostatische Gleichgewicht stabil oder instabil. Diese Forderung läßt sich für den Fall der geostrophischen Bewegung verallgemeinern, indem man zur SummeS die kinetische Longitudinalenergie der Partikel (je Maßeinheit) addiert. Dieses letztere Resultat läßt sich unmittelbar auf den Fall des permanenten Kreiswirbels ausdehnen.
    Abstract: Summary A particle of air which undergoes but adiabatic changes of state occupies its position of equilibrium inside a mass of air in hydrostatic equilibrium if the sumS of its specific enthalpy and of its potential energy per unit of mass assumes an extreme value. According as this extreme is a minimum or a maximum the state of hydrostatic equilibrium is stable or unstable. This postulate can be generalized in case of geostrophic state of motion on condition that the kinetic longitudinal energy of the particle per unit of mass is added to the sumS. This last result can be immediately extended on the case of a permanent circular vortex.
    Notes: Résumé Une particule qui ne subit que des transformations adiabatiques, occupe sa position d'équilibre au sein d'une masse d'air en équilibre hydrostatique, lorsque la sommeS de son enthalpie spécifique et de son énergie potentielle par unité de masse est extremum. Suivant que cet extremum est un minimum ou un maximum, l'état d'équilibre hydrostatique est stable ou instable. On peut généraliser cette proposition au cas de l'état de mouvement géostrophique, à condition d'ajouter, à la sommeS, l'énergie cinétique longitudinale, par unité de masse, de la particule. On peut étendre immédiatement ce dernier résultat au cas du tourbillon circulaire permanent.
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    Meteorology and atmospheric physics 1 (1949), S. 384-407 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Summary Many cold fronts which cross the principal crest of the Alps in a Southerly direction and penetrate into the region are very avtive in that region. Other cold fronts, however, die out almost completely when crossing the Southern Alps, due to Föhn phenomena. In the present paper, the behaviour of cold air currents crossing the Alps and penetrating the Southern Alps region is thoroughly discussed by analysing individual examples. Thereby it is shown that a clear distinction between the two kinds of cold air invading the Southern Alps region can be drawn from considering the characteristic features of the airstream. Both cases can be easily recognised by examination of the relevant upper air charts. Cold fronts are active in the Southern Alps when this region lies ahead of a high-level trough in the upper air: whilst cold fronts die out through the effect of the Föhn when the Southern Alps lie to the rear of a high-level trough.
    Abstract: Résumé De nombreux fronts froids dirigés vers le Sud et qui traversent les Alpes se révèlent extrêmement actifs sur le versant sud, de cette chaîne. D'autres fronts au contraire disparaissent presque complètement en franchissant le faîte montagneux à cause du phénomène de foehn. On examine ici des cas déterminés de passages de masses d'air froides par-dessus les Alpes et leur écoulement sur le versant opposé. En repérant certaines caractéristiques de ces courants, il est possible de distinguer nettement les deux types d'invasion froide au Sud des Alpes. Cette distinction est particulièrement facile par l'emploid des cartes de pression en altitude. On constate alors qu'un front froid reste actif en traversant les Alpes lorsque la partie antérieure d'un couloir de basse pression en altitude se trouve sur le versant sud, mais qu'il y a frontolyse par foehn lorsque la partie postérieure de ce couloir se trouve sur cette région.
    Notes: Zusammenfassung Viele Kaltfronten, die mit Südkurs den Alpenhauptkamm überschreiten und in das Südalpengebiet eindringen, sind dort außerordentlich wetterwirksam. Andere Kaltfronten, die über die Alpen hinwegziehen, werden dagegen in den Südalpen durch Föhnerscheinungen fast völlig aufgelöst. In vorliegender Arbeit wird an Einzelbeispielen das Verhalten von Kaltluftströmungen beim Überqueren der Alpen und beim Eindringen in das Südalpengebiet eingehend untersucht. Dabei zeigt sich, daß durch charakteristische Merkmale der Strömmungen eine einwandfreie Unterscheidung der beiden Arten von Kaltlufteinbrüchen in das Südalpengebiet möglich ist. Vor allem lassen sich beide Fälle durch Anwendung der Höhenwetterkarte gut auseinanderhalten. Es ergibt sich, daß eine Kaltfront dann die Südalpen wetterwirksam überquert, wenn dieses Gebiet auf der Vorderseite eines in der Höhenkarte in Erscheinung tretenden Höhentroges liegt, daß dagegen die Front durch Föhnwirkung aufgelöst wird, wenn die Südalpen auf der Rückseite des Höhentroges liegen.
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    Meteorology and atmospheric physics 1 (1949), S. 273-294 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Summary The paper gives a general view of the investigations dealing with the general circulation of the atmosphere in middle latitudes, carried out by the Department of Meteorology of the University of Chicago under the direction of Prof.C. G. Rossby during the academic year 1946–47. The zonal circulation in the middle latitudes of the northern hemisphere shows, particularly during the winter halfyear and normally between heights of 5 and 15 km, a fairly narrow band of very strong western winds with the character of a free jet. The maximum of intensity of this wind-band appears at the level of the tropopause (300–200 mb.). The wind velocity is rapidly decreasing to the south of the wind maximum. The zonal windband is located within or immediately to the south of an equally narrow zone in which the contrast of temperature between the polar and equatorial regions reaches its highest degree. There is a strong inclination of the tropopause within the zonal wind-band. Frequently, even a discontinuity can be found, the height of the tropopause corresponding to that of the polar atmosphere in the north and to that of the equatorial atmosphere in the south of the wind-band. Below the wind-band, often a well defined frontal zone is situated, ending in the upper layers of the troposphere a little to the north of the wind-band. The upper west-wind belt embracing the whole earth has a wavelike form with wave-lengths from about 50 to 120 degrees of longitude. These waves show but a small velocity of propagation and do not appear to be connected with the ordinary short and unstable frontal waves of the troposphere. On the other hand, they seem to influence considerably the behaviour as well as the movement of these short waves of the lower atmosphere. However, the upper waves are unstable insofar as the amplitude of the oscillation (formation of meander) is little by little increasing so much as to form whirls at the margins of the wind-band: of cyclonic nature and cold thermic structure at the southern side, of anticyclonic nature and warm thermic structure at the northern side. This cutting off of air-masses from within the wind-band causes an exchange of air-masses between high and low latitudes which appears to be of greatest importance in the tropospheric air-layers above 700 mb. Theoretical investigations show that the observed meridional windprofiles at the level of the tropopause agree rather well with those theoretically computed on the assumption of a constant vertical component of absolute vorticity within the lateral large-scale exchange of air-masses in the middle latitudes. Theoretical wind-profiles of this kind show, in low latitudes, such a strong meridional wind-gradient as to cause inertia instability at the southern edge of the wind-band. Due to them, the meridional wind-increase ceases more or less abruptly in latitudes of 40 to 30 degrees. The conclusion can be drawn from the simultaneous appearance of the wind-band and the frontal zone below it that the formation of the west-wind-band must be accompanied by a dynamic concentration of solenoids within the band, a phenomenon in a similar form to be found with oceanic currents. In addition to these important results of recent American researches, shortly indicated above, several Austrian investigations referring to some questions of the discussed problems are mentioned.
    Abstract: Résumé L'auteur donne un aperçu des recherches sur la circulation générale de l'atmosphère sous les latitudes moyennes entreprises par le Department of Meteorology of the University of Chicago, sous la direction du professeurC. G. Rossby en 1946/47. Dans la circulation zonale des latitudes moyennes de l'hémisphère nord apparaît, en hiver surtout, une région assez étroite de très forts vents d'Ouest entre 5 et 15 km. d'altitude qui a l'allure d'un jet aérien délimité. Le maximum de vitesse de ce courant se produit au niveau de la tropopause (300 à 200 mb.); au Sud de ce maximum, la vitesse décroît rapidement. Le courant zonal se trouve dans une bande étroite, ou immédiatement au Sud de celle-ci, dans laquelle les différences de température entre les régions polaires et équitoriales ont leurs plus grandes valeurs. A l'intérieur du courant la tropopause monte rapidement et présente même souvent une discontinuité: au Nord, son altitude correspond à celle de l'atmosphère polaire, au Sud à celle de l'atmosphère équatoriale. Au-dessous du même courant, on rencontre souvent une zone frontale bien développée qui dans les couches supérieures de la troposphère se termine un peu au Nord du courant zonal. La partie supérieure du courant d'Ouest présente une structure ondulée, avec des longueurs d'onde comprises entre 50° et 120° de longitude. Ces ondes ne se déplacent que lentement et ne paraissent pas être de même nature que les ondes frontales instables de la troposphère. D'autre part elles semblent exercer une action décisive sur l'allure et sur le mouvement des courtes ondes frontales inférieures. Les ondes supérieures sont instables en tant que sur leurs bords il peut se produire des ondulations donnant naissance à des tourbillons: sur le bord sud du courant apparaissent des tourbillons cycloniques et froids; sur le bord nord des tourbillons anticycloniques et chauds. Le courant d'Ouest expulse de la sorte des masses d'air et entretient un échange de masses entre les hautes et les basses latitudes qui semble avoir une grande importance dans les couches troposphériques au-dessus de 700 mb. Des recherches théoriques montrent que les profils méridiens du vent observés au niveau de la tropopause concordent fort bien avec ceux qu'exige la constance d'une composante verticale tourbillonnaire dans le cadre de l'échange turbulent à grande échelle des latitudes moyennes. De tels profils théoriques du vent montrent, aux basses latitudes, un gradient méridien du vent tellement grand que des états instables d'inertie doivent se produire au Sud du courant d'Ouest. Ces zones d'instabilité introduisent une cessation plus ou moins brusque de l'accroissement méridional de vitesse du vent vers 40° à 30° de latitude. Le fait que le courant d'Ouest étroit se superpose à une zone frontale inférieure amène à conclure que la formation de ce courant est accompagnée d'une concentration dynamique de solénoïdes à son niveau, phénomène analogue à celui que l'on observe dans les courants marins. Faisant suite à cet examen des travaux américains, l'article énumère encore quelques résultats de recherches autrichiennes relatives à certaines questions du même problème.
    Notes: Zusammenfassung Im folgenden wird ein Überblick über die Untersuchungen über die allgemeine Zirkulation der Atmosphäre in den mittleren Breiten der Erde gegeben, die vom Department of Meteorology of the University of Chicago unter der Leitung von Prof.C. G. Rossby im Akademiejahr 1946 bis 1947 ausgeführt worden sind. In der zonalen Zirkulation der mittleren Breiten der Nordhemisphäre zeigt sich vor allem im Winterhalbjahr normalerweise zwischen 5 und 15 km Höhe ein verhältnismäßig schmales Band von sehr starken Westwinden, das den Charakter eines Freistrahls besitzt. Das Intensitätsmaximum dieses Windbandes tritt im Tropopausenniveau (300 bis 200 mb) auf. Südwärts des Windmaximums nimmt die Windgeschwindigkeit sehr rasch auf niedrige Werte ab. Das zonale Windband liegt innerhalb oder knapp südlich einer ebenfalls relativ schmalen Zone, in der der Temperaturgegensatz zwischen den polaren und äquatorialen Gebieten konzentriert ist. Im Bereich des zonalen Windbandes steigt die Tropopause steil an, wobei häufig sogar eine Unstetigkeit auftritt, indem nördlich desselben ihre Höhe jener der polaren Atmosphäre entspricht, südlich davon jener der äquatorialen. Unter dem Windband liegt häufig eine gut ausgebildete Frontalzone, die in den oberen Troposphärenschichten etwas nördlich des Windbandes endigt. Das obere Westwindband zeigt rund um die ganze Erde einen wellenförmigen Verlauf mit Wellenlängen von etwa 50° bis 120° Längengraden. Diese Wellen weisen nur eine geringe Fortpflanzungsgeschwindigkeit auf und scheinen mit den gewöhnlichen kurzen, instabilen troposphärischen Frontalwellen keine nähere Beziehung zu haben. Anderseits scheinen sie sowohl das Verhalten, wie auch die Bewegung dieser kurzen unteren Wellen in maßgebender Weise zu beeinflussen. Die oberen Wellen sind insofern instabil, als die meridionale Schwingungsweite (Mäanderung) allmählich sich so verstärkt, daß es an den Rändern des Windbandes zur Bildung von Wirbeln kommt: auf der Südseite zyklonischer Natur und kalten thermischen Aufbaues, auf der Nordseite antizyklonischer Natur und warmen thermischen Aufbaues. Diese Ausstoßung von Luftmassen aus dem Windbandbereich führt zu einem Luftmassenaustausch zwischen hohen und niedrigen Breiten, der wie es scheint in den troposphärischen Schichten oberhalb 700 mb von ausschlaggebender Bedeutung ist. Theoretische Untersuchungen zeigen, daß die beobachteten meridionalen Windprofile im Tropopausenniveau recht gut mit solchen übereinstimmen, die der Forderung einer konstanten vertikalen Wirbelkomponente im Bereich des großräumigen seitlichen Austausches der mittleren Breiten genügen. Solche theoretische Windprofile zeigen in niedrigen Breiten ein so großes meridionales Windgefälle, daß es am Südrand des Windbandes zu Trägheitsinstabilitäten kommt. Sie führen zu einem mehr oder minder unvermittelten Abbruch der meridionalen Windzunahme in 40° bis 30° Br. Das gleichzeitige Auftreten von Windband und Frontalzone darunter führt zur Schlußfolgerung, daß es bei der Ausbildung des Westwindbandes zu einer dynamischen Konzentration von Solenoiden in seinem Bereich kommen muß, zu ähnlichen Vorgängen, wie sie bei ozeanischen Strömen auftreten. Im Anschluß an diese hier kurz angedeuteten wichtigen Ergebnisse dieser neueren amerikanischen Arbeiten wird auf einige Ergebnisse österreichischer Untersuchungen hingewiesen, die einige Fragen der obigen Probleme betreffen.
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  • 98
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 99
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    Rheologica acta 6 (1967), S. 74-76 
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 100
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    Rheologica acta 6 (1967), S. 30-53 
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Summary Measurements of the isothermal-isobaric volume retardation in crosslinked and non-crosslinked polystyrene are reported. The measurements have been carried out applying the temperature-jump method, and, for the first time, also the pressure-jump method. For the measurements using the temperature-jump method a quartz-glassdilatometer has been used which allows the registration of volume changes of ±7·106 cm3. A pressure dilatometer has been developed for the measurements according to the pressure-jump method which permits volumemeasurments of the same precision in the pressure-range between 1 and 60 atmospheres. The experimental results show that for the volume retardation of polystyrene a measurable linear region exists. For this case of linear retardation behaviour various kinetic theories predict an exponential time dependence of the deviation of the volume from the equilibrium value, which is due to the existence of a single retardation time. This result is not confirmed by our experiments. The volume retardation in the linear region — at least for polystyrene — can in no case be described in terms of a single retardation time, but only by a distribution of retardation times. It turns out, that the retardation function (distribution function of retardation times) in the linear region differs after a previous temperature change from that after a previous pressure change. This result can be confirmed by theoretical considerations which follow fromMeixner's thermodynamic theory of linear relaxation phenomena.
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