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  • Other Sources  (22)
  • 1939-40
  • Mechanical Engineering
  • 1960-1964  (10)
  • 1940-1944  (12)
  • 1
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    In:  Ztschr. Forst-, Jagdwesen 73: 201-246
    Publication Date: 1941
    Description: Beschreibung des Zusammenhangs zwischen der Eizahl und der Kokonzahl der Kiefernhornblattwespe auf das Massenauftreten KATASTER-BESCHREIBUNG: Betimmung der kritischen Anzhal Eier und der kritischen Anzahl Winter- und Sommerkokons für das Massenauftreten KATASTER-DETAIL:
    Keywords: Sachsen, Brandenburg, Mecklenburg-Vorpommern ; 1939-40 ; Insekten ; Kiefer ; Pflanzenschädling
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  • 2
    facet.materialart.
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    In:  Ztschr. angew. Ent. 29: 367-411
    Publication Date: 1942
    Description: Untersuchungen zu biotischen und abiotischen Ursachen für den Zusammenbruch der Population der Kiefernbuschhornblattwespe KATASTER-BESCHREIBUNG: Ursachen für den Zusammenbruch der Kiefernbuschhornblattwespen-Population neben dem harten Winter 1939/40 eine andauernde Schönwetterperiode Ende April/Anfang Mai und vor allem stärkere Vermehrung der Feinde KATASTER-DETAIL: Delta sonn +, (April-Mai) führte zu erhöhten Vertrocknen der Kokons der Kiefernbuschhornblattwespe im Jahr 1940
    Keywords: Nordostdeutschland ; 1939-40 ; Kiefer ; Pflanzenschädling ; Temperatur ; Sonnenscheindauer
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  • 3
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    In:  Ztschr. Pfl.krankh. 51: 257-278
    Publication Date: 1941
    Description: Beschreibung der Massenvermehrung der Kiefernblattwespe, Hauptgrung ist die Umwandlung von ursprünglich Laubwaldgesellschaften in reine Kieferngesellschaften, Bedeutung der Temperatur für das Überliegen der Larven KATASTER-BESCHREIBUNG: Temperatur und Luftfeuchte für das Überliegen der Larven entscheidend und damit auch für ein Massenauftreten im darauffolgenden Jahr, Begünstigung der Parasitierung der Kieferblattwespe KATASTER-DETAIL: Delta T- (Juli-August und im Winter), dann Geschlechterfolge von Diprion pini stark dezimiert
    Keywords: Slowakei ; 1939-40 ; Insekten ; Luftfeuchte ; Kiefer ; Pflanzenschädling ; Temperatur ; Parasit
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  • 4
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    In:  Ann. Ent. fenn., Helsinki, 8: 143-163
    Publication Date: 1942
    Description: Vertrockungnung der Eberesche, der Salweide durch den Befall mit Kleinschmetterlingen, bzw. Käfern und sekundär Pilzen, Bescchreibung der Prozesse und Auswirkungen KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Finnland ; 1939-40 ; Insekten ; Forst ; Pflanzenkrankheit ; Pflanzenschädling
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  • 5
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    In:  Mitt. Forstwirtsch. u. -wissensch. 12: 25-68
    Publication Date: 1941
    Description: Auswertung verschiedener Parameter (Nonnenraupen, Falterflug) in unterschiedlichen Überwachungsbereichen der Forstentomologischen Dienststellen, Befallsermittlungsverfahren nach der Wellensteinschen Methode KATASTER-BESCHREIBUNG: Rhytmische Schwankungen der plötzlichen Übervermehrung, 10 oder 12 jährige Perioden, Bezug zu Schwankungen der Umweltbedingungen KATASTER-DETAIL:
    Keywords: Nord- und Mitteldeutschland ; 1939-40 ; Insekten ; Fichte ; Forst ; Kiefer ; Pflanzenschädling
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  • 6
    Publication Date: 2019-05-23
    Description: The goal of this contract was to determine the g environment under which the GC159C Gas-Bearing Spinmotor (GBSM) could reliably operate. This was fulfilled by building and testing of four GBSM's, a test fixture, and a "dummy" gyro. The test program was divided into two phases when a gas bearing improvement was required to withstand JPL shock requirement of 200 g. Phase I determined existing g capabilities and performance of the GC159C GBSM and gimbal-case structure. Phase II increased GBSM capability to meet required JPL g environments. Life tests were run on two GBSM's which were shocked at a high level to obtain bearing contact while rotating at their operating speed of 23,000 rpm. A third (nonoperating) GBSM was exposed to JPL maximum shock levels, and a fourth (nonoperating) GBSM was exposed to random vibration. Both nonoperating GBSM's were then subjected to life testing.
    Keywords: Mechanical Engineering
    Type: NASA-CR-63180 , Aero Report 1727-FR1
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  • 7
    Publication Date: 2019-06-28
    Description: The results of this investigation indicate that the penetration of projectiles into quasi-infinite targets can be correlated as a function of the maximum momentum per unit area possessed by the projectiles. The penetration of projectiles into aluminum, copper, and steel targets was found to be a linear function while the penetration into lead targets was a nonlinear function of the momentum per unit area of the impacting projectiles. Penetration varied inversely as the projectile density and the elastic modulus of the target material for a given projectile momentum per unit area. Crater volumes were found to be a linear function of the kinetic energy of the projectile, the greater volumes being obtained in the target materials which had the lowest yield strength and the lowest speed of sound.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-238
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  • 8
    Publication Date: 2019-08-24
    Description: The strength of representative types of flush-riveted joints has been determined by testing 865 single-shearing, double-shearing, and tensile specimens representing 7 types of rivet and 18 types of joint. The results, presented in graphic form, show the stress at failure, type of failure, and d/t ratio. In general, 'dimpled' joints were appreciably stronger than countersunk or protruding-head joints, but their strength was greatly influenced by constructional details. The optimum d/t ratios have been determined for the several kinds of joints. Photomacrographs of each type show constructional details and, in several instances, cracks in the sheet.
    Keywords: Mechanical Engineering
    Type: NACA-SR-142
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  • 9
    Publication Date: 2019-07-11
    Description: In the present paper an investigation is made of two stages of a multistage turboblower having a vaneless diffuser behind the impeller and guide vanes at the inlet to the nest stage. The method employed was that of investigating the performance of the successive elements of the blower (the impeller, vaneless diffuser, ets.) whereby the kinematics of the flow through the blower could be followed and the pressure at the different points computed. The character of the flow and the physical significance of the loss coefficients could thereby be determined so as to secure the best agreement of the computed with the actual performance of the blower. Since the tests were carried out for various delivery volumes, the dependence of the coefficients on a number of factors (angle of attack, velocities, etc.) could be obtained. The distribution of the losses that occur during the transformation of dynamic pressure at the impeller exit into static pressure could be found and likewise the range within which the friction coefficient varies in the vaneless diffuser. With the aid of factors having a certain physical significance, the centrifugal blower could be computed on the basis of a more or less schematical consideration of the phenomena occuring during the air flow through it, and the use of arbitrary factors and recourse to the geometrical similtude law thus avoided. The present investigation largely summarizes all the previous work af the CHI Blower Section on the different elements of a centrifugal blower. Some considerations on the analysis of model test data for application to full-scale are presented in the appendix.
    Keywords: Mechanical Engineering
    Type: NACA-TM-1043 , Report of the Central Aero-Hydrodynamical Institute, Moscow; Rept-191
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  • 10
    Publication Date: 2019-08-17
    Description: A series of investigations using the fatigue spin rig to study the effect of several factors contributing to rolling contact fatigue life is summarized. Ball specimens of 1/2 and 9/16 inch diameter were tested at maximum theoretical Hertz compressive stresses in the range of 600,000 to 750,000 psi. Life was found to vary inversely with the tenth power of stress. In forging fiber studies, a greater concentration of failures and poorer life were observed where the greatest angle of intersection between the fiber flow lines and the surface occurred. This effect was independent of alloy composition. Higher lubricant viscosity was found to increase fatigue life, Lubricants having the same viscosity but of different base stock produced wide differences in life that correlated with the pressure viscosity coefficient of the lubricant. Higher temperature produced lower fatigue life. Dry powder lubricants produced poor fatigue life at 450 F; failure appearance indicated that the lubricant particles probably acted as minute stress raisers. In metallographic studies, nonmetallic inclusions were found to have a deleterious effect on fatigue life the inclusion size, location, composition, and condition of the matrix being contributing factors; failures were by shear cracking in the subsurface zone of maximum shear stress and eventual propagation into a shallow surface spall. Vacuum melting improved fatigue life, although a general correlation between cleanliness and fatigue life was not found. Life results for ten different bearing materials are presented.
    Keywords: Mechanical Engineering
    Type: NASA-TR-R-60
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  • 11
    Publication Date: 2019-08-16
    Description: An axial-flow-pump stage was designed by utilizing blade-element methods in conjunction with axial-flow-compressor blade-element theory. This report presents the blade-element data of the pump stage in both the noncavitating and cavitating conditions. The noncavitating blade- element performance is compared with design rules. The results indicated that some modification of the compressor design equations for computing minimum-loss incidence and deviation angles may be necessary for application to an axial-flow-pump design. Minimum values of observed rotor loss were slightly lower than anticipated from compressor results. At the design flow coefficient the rotor-blade elements were not operating at the reference incidence angles, and the experimental efficiency was lower than the design value. The observed head rise was very close to the design. An attempt was made to estimate the potential of this rotor by using the minimum measured values of loss coefficient and observed energy input at the design flow. Performance of the pump at a suction specific speed of approximately 13,000 (cavitation number k approximately equals 0.12) showed only a slight dropoff in performance in the cavitation inception region from the noncavitating results. The observed performance at a suction specific speed of approximately 16,000 (k approximately equals 0.09) is also presented for comparison.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-1109 , E-1127
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  • 12
    Publication Date: 2019-08-15
    Description: Part I contains the results of a preliminary experimental investigation of a particular design of an underwater ramjet or hydroduct powered by compressed air. The hydroduct is a propulsion device in which the energy of an expanding gas imparts additional momentum to a stream of water through mixing. The hydroduct model had a fineness ratio of 5.9, a maximum diameter of 3.2 inches, and a ratio of inlet area to frontal area of 0.32. The model was towed at a depth of 1 inch at forward speeds between 20 and 60 feet per second for airflow rates from 0.1 to 0.3 pound per second. Longitudinal force and pressures at the inlet and in the mixing chamber were determined. The hydroduct produced a positive thrust-minus-drag force at every test speed. The force and pressure coefficients were functions primarily of the ratio of weight airflow to free-stream velocity. The maximum propulsive efficiency based on the net internal thrust and an isothermal expansion of the air was approximately 53 percent at a thrust coefficient of 0.10. The performance of the test model may have been influenced by choking of the exit flow. Part II is a theoretical development of an underwater ramjet using air as "fuel." The basic assumption of the theoretical analysis is that a mixture of water and air can be treated as a compressible gas. More information on the properties of air-water mixtures is required to confirm this assumption or to suggest another approach. A method is suggested from which a more complete theoretical development, with the effects of choking included, may be obtained. An exploratory computation, in which this suggested method was used, indicated that the effect of choked flow on the thrust coefficient was minor.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-991 , L-1249
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  • 13
    Publication Date: 2019-08-15
    Description: Results are presented of a series of fatigue tests to study crack propagation and the resulting stress distributions in tension panels. The panels were all of the same general design, and configurations varied mainly in the relative amount of cross-sectional area in the skin, stiffeners, and flanges. The panels were constructed of 2024-T3 and 7075-T6 aluminum alloys. It was found that the average rate of crack growth was slower in panels made of 2024-T3 aluminum alloy than in panels made of 7075-T6 aluminum alloy. All cracks initiated in the skin, and the slowest crack growth was measured in configurations where the highest percentage of cross-sectional area was in the stiffeners. Strain-gage surveys were made to determine the redistribution of stress as the crack grew across the panels. As a crack approached a given point in the skin, the stress at that point increased rapidly. The stress in the stiffeners also increased as the crack approached the stiffeners. During the propagation of the crack the stress was not distributed uniformly in the remaining area.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-543 , L-1136
    Format: text
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  • 14
    Publication Date: 2019-07-13
    Description: The changes produced on metallic surfaces as a result of grinding and polishing are not as yet fully understood. Undoubtedly there is some more or less marked change in the crystal structure, at least, in the top layer. Hereby a diffusion of separated crystal particles may be involved, or, on plastic material, the formation of a layer in greatly deformed state, with possible recrystallization in certain conditions. Czochralski verified the existence of such a layer on tin micro-sections by successive observations of the texture after repeated etching; while Thomassen established, roentgenographically by means of the Debye-Scherrer method, the existence of diffused crystal fractions on the surface of ground and polished tin bars, which he had already observed after turning (on the lathe). (Thickness of this layer - 0.07 mm). Whether this layer borders direct on the undamaged base material or whether deformed intermediate layers form the transition, nothing is known. One observation ty Sachs and Shoji simply states that after the turning of an alpha-brass crystal the disturbance starting from the surface, penetrates fairly deep (approx. 1 mm) into the crystal (proof by recrystallization at 750 C).
    Keywords: Mechanical Engineering
    Type: NACA-TM-1072 , Naturwissenschaften; 20; 22/24; 416-419
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  • 15
    Publication Date: 2019-07-13
    Description: Hardy's statement that the frictional force is largely adhesion, and to a lesser extent, deformation energy is proved by a simple experiment. The actual contact surface of sliding contacts and hence the friction per unit of contact surface was determined in several cases. It was found for contacts in normal atmosphere to be about one-third t-one-half as high as the macroscopic tearing strength of the softest contact link, while contacts annealed in vacuum and then tested, disclosed frictional forces which are greater than the macroscopic strength.
    Keywords: Mechanical Engineering
    Type: NACA-TM-1074 , Wissenschaftliche Veroeffentlichungen aus den Siemens-Werken; 17; 4; 38-42
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  • 16
    facet.materialart.
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    In:  CASI
    Publication Date: 2019-07-13
    Description: In internal combustion engines, steam engines, air compressors, and so forth, the piston ring plays an important role. Especially, the recent development of Diesel engines which require a high compression pressure for their working, makes, nowadays, the packing action of the piston ring far more important than ever. Though a number of papers have been published in regard to researches on the problem of the piston ring, none has yet dealt with an exact measurement of pressure exerted on the cylinder wall at any given point of the ring. The only paper that can be traced on this subject so far is Mr. Nakagawa's report on the determination of the relative distribution of pressure on the cylinder wall, but the measuring method adopted therein appears to need further consideration. No exact idea has yet been obtained as to how the obturation of gas between the piston and cylinder, the frictional resistance of the piston, and the wear of the cylinder wall are affected by the intensity and the distribution of the radial pressure of the piston ring. Consequently, the author has endeavored, by employing an apparatus of his own invention, to get an exact determination of the pressure distribution of the piston ring. By means of a newly devised ring tester, to which piezoelectricity of quartz was applied, the distribution of the radial pressure of many sample rings on the market was accurately determined. Since many famous piston rings show very irregular pressure distribution, the author investigated and achieved a manufacturing process of the piston ring which will exert uniform pressure on the cylinder wall. Temperature effects on the configuration and on the mean spring power have also been studied. Further, the tests were performed to ascertain how the gas tightness of the piston ring may be affected by the number or spring power. The researches as to the frictional resistance between the piston ring and the cylinder wall were carried out, too. The procedure of study, and experiments conducted by the author, on this subject will be fully described in the following paragraphs.
    Keywords: Mechanical Engineering
    Type: NACA-TM-1057 , 32st Rep. of Okochi Res. Lab.: Scientific Papers of the Inst. of Physical and Chemical Research, Tokyo University; 10; 182; 107-185
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  • 17
    facet.materialart.
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    In:  CASI
    Publication Date: 2019-07-13
    Description: The discovery and introduction of the internal combustion engine has resulted in a very rapid development in machines utilizing the action of a piston. Design has been limited by the internal components of the engine, which has been subjected to ever increasing thermal and mechanical stresses, Of these internal engine components, the piston and piston rings are of particular importance and the momentary position of engine development is not seldom dependent upon the development of both of the components, The piston ring is a well-known component and has been used in its present shape in the steam engine of the last century, Corresponding to its importance, the piston ring has been a rich field for creative activity and it is noteworthy that in spite of this the ring has maintained its shape through the many years. From the many and complicated designs which have been suggested as a packing between piston and cylinder wall hardly one suggestion has remained which does not resemble the original design of cast iron rectangular ring.
    Keywords: Mechanical Engineering
    Type: NACA-TM-1056 , ATZ Automobiltechnische Zeitschrift; 45; 3; 62-67
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  • 18
    Publication Date: 2019-07-10
    Description: A titanium nitride coating for graphite, prepared by deposition process, protected test specimens for 60 seconds the vapors in a supersonic ceramic-heated air jet with a stagnation temperature of approximately 2,250 K. For the same test conditions, coated specimens showed no damage to the graphite body for the 60-second test, whereas uncoated specimens were very severely damaged after 20 seconds and were destroyed toward the end of the test. A discussion of the coating of these graphite specimens and of some of the conditions necessary for the utilization of oxidizable substances as oxidation-protective coatings for bodies facing high convective heat transfer in the atmosphere is presented.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-722 , L-1304
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  • 19
    Publication Date: 2019-07-11
    Description: The exact mathematical treatment of the problem is possible by replacing the propeller blade by a homogeneous prismatic rod. Conclusions can them be drawn as to the behavior of an actual propeller, since tests on propeller blades have indicated a qualitative agreement with the homogeneous rod. The natural frequencies are determined and the stressing of the systems under the various vibration modes are discussed.
    Keywords: Mechanical Engineering
    Type: NACA-TM-1051 , Jahrbuch 1938 der Deutschen Luftfahrtforschung; 141-159
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  • 20
    Publication Date: 2019-08-15
    Description: A series of unbraked (freely rolling) taxi tests were conducted at the Langley landing-loads track with a 32 x 8.8, type 7, 22-ply-rating ribbed-tread aircraft tire to obtain data on tire retardation forces developed during rolling in both slush and water. The forward speeds of the tests ranged from 59 to 104 knots. Tire inflation pressures of 350 and 115 pounds per square inch were used. Results indicated a parabolic increase of retardation force with increasing forward velocity for both slush- and water-covered runway surfaces. The retardation force was found to increase approximately linearly with increasing water depth. Drag coefficients appropriate to the equations used are presented. Calculations made to determine the effect of slush on the take-off distance of a jet transport are in agreement with data obtained from an actual take-off in slush for this airplane. This is an interim report which deals with the effect of slush on the acceleration and the ground-run distance of airplanes during take-off.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-552 , L-1260
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  • 21
    Publication Date: 2019-08-15
    Description: Several currently available nonmetallic insulation materials that may be bonded onto liquid-hydrogen tanks and sealed against air penetration into the insulation have been investigated for application to rockets and spacecraft. Experimental data were obtained on the thermal conductivities of various materials in the cryogenic temperature range, as well as on the structural integrity and ablation characteristics of these materials at high temperatures occasioned by aerodynamic heating during atmospheric escape. Of the materials tested, commercial corkboard has the best overall properties for the specific requirements imposed during atmospheric flight of a high-acceleration rocket vehicle.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-476 , E-806
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  • 22
    Publication Date: 2019-08-15
    Description: Three facets of fatigue testing are discussed in relation to problems involved in evaluating the fatigue life of structural parts. These facets are variable-amplitude loading, fatigue-crack propagation, and equivalent fatigue loading. Experimental test results are included to support conclusions.
    Keywords: Mechanical Engineering
    Type: NASA-TN-D-725 , L-1434
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