ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Surface analysis of In1−x Ga x As y P1−y epilayer growth by liquid-phase epitaxy (1986)

Su, Y. K. ; Wu, M. C. ; Chang, C. Y.

Springer

Journal of materials science 5 (1986), S. 91-92

add to mindlist on the mindlist

Details

ISSN: 1573-4811

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01671449

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Oscillations of upper-air circulation and anomalies in the surface climate of the tropics (1982)

Hastenrat, St. ; Wu, M. C.

Springer

Meteorology and atmospheric physics 31 (1982), S. 1-37

add to mindlist on the mindlist

Details

ISSN: 1436-5065

Source: Springer Online Journal Archives 1860-2000

Topics: Geography , Physics

Description / Table of Contents: Zusammenfassung Zirkulationsänderungen in der freien Atmosphäre und Anomalien im Bodenklima der Tropen werden hauptsächlich auf Grund von Radiosondenaufstiegen und Bodenbeobachtungen im Zeitraum 1960–79 untersucht. Monatliche Anomalien von Meeresoberflächentemperatur (SST), Druck an Station oder im Meeresniveau (STP/SLP), absoluter Topographie und Wind der 850 and 200 mb Niveaus und relativer Topographie 200/850 mb werden in Form übergreifender Mittel und lurch Spektralanalyse dargestellt. Diese empirische Untersuchung liefert den Rahmen für eine Hypothese der Mechanismen großräumiger Druckschwankungen. In einem Stadium kalten Oberflächenwassers im aquatorialen Pazifik herrscht hoher Bodendruck über dem östlichen Siidpazifik und niederer Druck über Australasien. Verstärkte Bewölkung begünstigt eine Abkühlung der Meeresoberfläche und danach der darüberliegenden Luftsaule über Australasien. Die damit einhergehende Tendenz fur einen westwärtigen Druckgradienten in der Hochtroposphäre führt zu einem Anstieg des Bodendrucks über Ausiralasien und Druckfall über dem östlichen Südpazifik. Das hat eine Erwärmung der Meeresoberflache und später der darüberliegenden Luftsäule im östlichen äquatorialen Pazifik zur Folge. Die Auswirkungen sind im zentralen und Ostpazifik am größten, so daß die hochtroposphärischen Druckniveaus nach Westen abfallen. Das bewirkt weiteres Absinken des Bodendrucks über dem östlichen Südpazifik und Druckanstieg über Australasien. Bewölkungsabnahme über Australasien erlaubt jetzt eine Erwärmung der Meeresoberfläche und der darüberliegenden Luftsäule. Die damit einhergehende Änderung in der Neigung der hochtroposphärischen Druckniveaus führt zu Absinken des Bodendrucks über Australasien und Druckanstieg über dem östlichen Südpazifik. Dies wiederum ist einer Abkühlung der Meeresoberläche zuträglich, womit sich der Zyklus vollendet. Es zeigt sich also, daß Vorgänge in der freien Atmosphäre und die Koppelung zwischen Atmosphäre und Ozean für die gegenläufigen Änderungen des Bodendrucks an den zwei großen Aktionszentren wesentlich ist.

Notes: Summary Variations of upper-air circulation related to anomalies in the surface climate of the tropics are studied mainly on the basis of radiosonde and surface observations during 1960–79. Monthly anomalies of sea surface temperature (SST), sea level or station pressure (SLP/STP), 850 and 200 mb height and wind, and 200/850 mb thickness are examined by running mean plots and spectral analysis. This empirical analysis provides the framework for a hypothesis of the mechanisms of large-scale pressure oscillations. During a stage of cold surface waters in the Equatorial Pacific, surface pressure is high over the Eastern South Pacific and low over Australasia. Enhanced cloudiness is conducive to a cooling of the upper ocean and subsequently of the overlying atmosphere over Australasia. The associated tendency towards a westward pressure gradient in the upper troposphere leads to a rise of surface pressure over Australasia and a drop over the Eastern South Pacific. This has as a consequence the warming of surface waters and of the overlying atmospheric column in the Eastern Equatorial Pacific. Effects are largest in the Central and Eastern Pacific, so that upper-tropospheric topographies decrease westward. This entails a continued drop of surface pressure over the Eastern South Pacific and a rise over Australasia. Decreased cloudiness over Australasia now allows warming of the upper ocean and later of the overlying atmospheric column. The implied change in the slope of upper-tropospheric topography leads to a surface pressure drop over Australasia and rise over the Eastern South Pacific. This in turn is cunducive to the cooling of surface waters, so that the cycle is completed. Upper-air processes and ocean-atmosphere coupling are thus essential for the seesaw of surface pressure between the centers of action.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02311340

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Probabilistic sensitivity and modeling of two-dimensional transport in porous media (1992)

Wu, M. C. ; Cawlfield, J. D.

Springer

Stochastic environmental research and risk assessment 6 (1992), S. 103-121

add to mindlist on the mindlist

Details

ISSN: 1436-3259

Keywords: Probabilistic model ; Sensitivity ; Contaminant transport

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract A reliability approach is used to develop a probabilistic model of two-dimensional non-reactive and reactive contaminant transport in porous media. The reliability approach provides two important quantitative results: an estimate of the probability that contaminant concentration is exceeded at some location and time, and measures of the sensitivity of the probabilistic outcome to likely changes in the uncertain variables. The method requires that each uncertain variable be assigned at least a mean and variance; in this work we also incorporate and investigate the influence of marginal probability distributions. Uncertain variables includex andy components of average groundwater flow velocity,x andy components of dispersivity, diffusion coefficient, distribution coefficient, porosity and bulk density. The objective is to examine the relative importance of each uncertain variable, the marginal distribution assigned to each variable, and possible correlation between the variables. Results utilizing a two-dimensional analytical solution indicate that the probabilistic outcome is generally very sensitive to likely changes in the uncertain flow velocity. Uncertainty associated with dispersivity and diffusion coefficient is often not a significant issue with respect to the probabilistic analysis; therefore, dispersivity and diffusion coefficient can often be treated for practical analysis as deterministic constants. The probabilistic outcome is sensitive to the uncertainty of the reaction terms for early times in the flow event. At later times, when source contaminants are released at constant rate throughout the study period, the probabilistic outcome may not be sensitive to changes in the reaction terms. These results, although limited at present by assumptions and conceptual restrictions inherent to the closed-form analytical solution, provide insight into the critical issues to consider in a probabilistic analysis of contaminant transport. Such information concerning the most important uncertain parameters can be used to guide field and laboratory investigations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01591333

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

A flexible classification method for evaluating the utility of automated workpiece classification system (1997)

Hsu, S. H. ; Hsia, T. C. ; Wu, M. C.

Springer

The international journal of advanced manufacturing technology 13 (1997), S. 637-648

add to mindlist on the mindlist

Details

ISSN: 1433-3015

Keywords: Automated workpiece classification ; Benchmark classification ; Flexible classification method ; Group technology

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract In group technology, workpieces are categorised into families according to their similarity in design or manufacturing attributes. This categorisation can eliminate design duplication and facilitate the production of workpieces. Much effort has been focused on the development of automated workpiece classification systems. However, it is difficult to evaluate the utility of such systems. The objective of this study was to develop a benchmark classification system based on global shape information for use in evaluating the utility of workpiece classification systems. A classification system has a high level of utility if its classification scheme is consistent with users' perceptual judgment of the similarity between workpiece shapes. Hence, in the proposed method, the consistency between a classification system and users' perceptual judgements is used as an index of the utility of the system. The proposed benchmark classification has two salient characteristics: 1. It is user-oriented, because it is based on users' judgments concerning the similarity of the global shape of workpieces. 2. It is flexible, allowing users to adjust the criteria of similarity applied in the automated workpiece classification. The development of this classification consisted of three steps: 1. Gathering row data on global shape similarity from a group of representative users and modelling the data by fuzzy numbers. 2. Developing benchmark classification for various similarity criteria by using fuzzy clustering analysis. 3. Developing indices for evaluating the appropriate number of workpiece categories and homogeneity within each group. The applicability of the benchmark classification system in evaluating the utility of automated workpiece classification systems was examined.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01350822

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

A skeleton-retrieving technique for aiding modular-fixtures design (1993)

Wu, M. -C. ; Yen, J. -Y.

Springer

The international journal of advanced manufacturing technology 8 (1993), S. 123-128

add to mindlist on the mindlist

Details

ISSN: 1433-3015

Keywords: Modular-fixtures design ; Skeleton

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract This paper presents a computer-aided approach to the design of modular fixtures by retrieving similar workpieces from an existing database. A database which stores previously-manufactured workpieces and their modular fixtures is assumed to be available. Each workpiece in the database is described by its skeleton and its boundary representation (BREP). The skeleton is a tree structure that describes the interior framework of a workpiece. Workpieces that have similar skeletons usually require similar fixturing configurations. For a new workpiece which requires a fixture to be designed, we first determine its skeleton and then retrieve existing workpieces with similar skeletons. The modular fixtures of these retrieved workpieces are displayed to assist engineers in designing new fixtures.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01749903

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Electronic Resource

A neural network approach to the classification of 3D prismatic parts (1996)

Wu, M. C. ; Jen, S. R.

Springer

The international journal of advanced manufacturing technology 11 (1996), S. 325-335

add to mindlist on the mindlist

Details

ISSN: 1433-3015

Keywords: Classification ; Group technology ; Neural network ; Prismatic parts ; Rectilinear ; Skeleton

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract This paper presents a neural network approach to the classification of 3D prismatic parts based on their global shape information modelling. In this approach, a 3D part is modelled by the contours of its three projected views, which are approximately represented by three rectilinear polygons. The global shape information of each polygon is modelled by its simplified skeleton, which originally is of a tree structure and can be represented by several vectors by a conversion method. These vectors are the input to a polygon classifier which is constructed on the basis of the back-propagation neural network model. The classification results of polygons can be used to group the 3D prismatic parts into families in a hierarchical manner, by setting different levels of similarity criteria. The proposed method for classifying 3D workpieces can be used to enhance the productivity of design and manufacturing processes. By retrieving and reviewing similar parts from the part families, the designers or process planners could be greatly assisted in performing a new task. That is, they can avoid the reinvention of an existing design and can create a new design by modifying existing ones.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01845691

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

7

Electronic Resource

An efficient method for creating benchmark classifications for automatic workpiece classification systems (1998)

Hsu, S. H. ; Hsia, T. C. ; Wu, M. C.

Springer

The international journal of advanced manufacturing technology 14 (1998), S. 481-494

add to mindlist on the mindlist

Details

ISSN: 1433-3015

Keywords: Automatic workpiece classification system ; Classification benchmarks ; Full-data classification ; Lean classification

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract The usefulness of an automatic workpiece classification system depends primarily on the extent to which its classification results are consistent with users' judgments. Thus, to evaluate the effectiveness of an automatic classification system it is necessary to establish classification benchmarks based on users' judgments. Such benchmarks are typically established by having subjects perform pair comparisons of all workpieces in a set of sample workpieces. The result of such comparisons is called a full-data classification. However, when the number of sample workpieces is very large, such exhaustive comparisons become impractical. This paper proposes a more efficient method, called lean classification, in which data on comparisons between the samples and a small number of typical workpieces are used to infer the complete classification results. The proposed method has been verified by using a small set of 36 sample workpieces and by computer simulation with medium to large sets of 100 to 800 sample workpieces. The results reveal that the method could produce a classification that was 71% consistent with the full-data classification while using only 10% of the total data.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01351394

Permalink