Frost growth and densification in laminar flow over flat surfaces

One-dimensional frost growth and densification in laminar flow over flat surfaces has been theoretically investigated. Improved representations of frost density and effective thermal conductivity applicable to a wide range of frost circumstances have been incorporated. The validity of the proposed model considering heat and mass diffusion in the frost layer is tested by a comparison of the predictions with data from various investigators for frost parameters including frost thickness, frost surface temperature, frost density and heat flux. The test conditions cover a range of wall temperature, air humidity ratio, air velocity, and air temperature, and the effect of these variables on the frost parameters has been exemplified. Satisfactory agreement is achieved between the model predictions and the various test data considered. The prevailing uncertainties concerning the role of air velocity and air temperature on frost development have been elucidated. It is concluded that that for flat surfaces increases in air velocity have no appreciable effect on frost thickness but contribute to significant frost densification, while increase in air temperatures results in a slight increase the frost thickness and appreciable frost densification.     

为在巴西引入数字电视提交的"公开咨询报告"文稿第291号

1 引言 由"国家电信局"(National Telecommunications Agency,Anatel)主持的数字电视在巴西的首次"公开咨询报告"(Public Consultation)的一年后,我们注意到:在这种技术的领域内,已经出现很多不同的显著事实.除了"CPqD基金会"报告以外,新的对比性测试曾经在美国(ATSC对DVB-T)和中国香港(ATSC,DVB-T和ISDB-T)都进行过.还有一些报道表明:中国台湾也进行了对比性测试,目的是确立自己的数字电视标准.     

Centroidal Voronoi Tessellation Algorithms for Image Compression, Segmentation, and Multichannel Restoration

Centroidal Voronoi tessellations (CVT's) are special Voronoi tessellations for which the generators of the tessellation are also the centers of mass (or means) of the Voronoi cells or clusters. CVT's have been found to be useful in many disparate and diverse settings. In this paper, CVT-based algorithms are developed for image compression, image segmenation, and multichannel image restoration applications. In the image processing context and in its simplest form, the CVT-based methodology reduces to the well-known k-means clustering technique. However, by viewing the latter within the CVT context, very useful generalizations and improvements can be easily made. Several such generalizations are exploited in this paper including the incorporation of cluster dependent weights, the incorporation of averaging techniques to treat noisy images, extensions to treat multichannel data, and combinations of the aforementioned. In each case, examples are provided to illustrate the efficiency, flexibility, and effectiveness of CVT-based image processing methodologies. Qiang Du is a Professor of Mathematics at the Pennsylvania State University. He received his Ph.D. from the Carnegie Mellon University in 1988. Since then, he has held academic positions at several institutions such as the University of Chicago and the Hong Kong University of Science and Technology. He has published over 100 papers on numerical algorithms and their various applications. His recent research works include studies of bio-membranes, complex fluids, quantized vortices, micro-structure evolution, image and data analysis, mesh generation and optimization, and approximations of partial differential equations. Max Guzburger is the Frances Eppes Professor of Computational Science and Mathematics at Florida State University. He received his Ph.D. degree from New York University in 1969 and has held positions at the University of Tennessee, Carnegie Mellon University, Virginia Tech, and Iowa State University. He is the author of five books and over 225 papers. His research interest include computational methods for partial differential equations, control of complex systems, superconductivity, data mining, computational geometry, image processing, uncertainty quantification, and numerical analysis. Lili Ju is an Assistant Professor of Mathematics at the University of South Carolina, Columbia. He received a B.S. degree in Mathematics from Wuhan University in China in 1995, a M.S. degree in Computational Mathematics from the Chinese Academy of Sciences in 1998, and a Ph.D. in Applied Mathematics from Iowa State University in 2002. From 2002 to 2004, he was an Industrial Postdoctoral Researcher at the Institute of Mathematics and Its Applications at the University of Minnesota. His research interests include numerical analysis, scientific computation, parallel computing, and medical image processing. Xiaoqiang Wang is a graduate student in mathematics at the Pennsylvania State University, working under the supervision of Qiang Du. Starting in September 2005, he will be an Industrial Postdoctoral Researcher at the Institute of Mathematics and its Applications at the University of Minnesota. His research interests are in the fields of applied mathematics and scientific computation. His work involves numerical simulation and analysis, algorithms for image processing and data mining, parallel algorithms, and high-performance computing.     

Achievement of home ownership among post‐war Australian cohorts

Entry costs to home ownership have been rising in Australia since the mid‐1950s but home ownership rates had not fallen by the mid‐1980s. Drawing from a national life history survey carried out in 1986–87, this paper shows that median ages for first time home buying have been declining among successive cohorts over the post‐war era. The paradox of rising entry costs and earlier home buying may be explained by rising labour force participation among women immediately after marriage and awareness of the increasing financial returns from long‐term home ownership. Among the later cohorts, early entry to home ownership appears to have been associated particularly strongly with wives' employment after marriage and husbands' incomes. The findings suggest that access to home ownership in the future may be increasingly limited to young adults having high household incomes.     

Solitary splenic metastasis of an adenocarcinoma of the ovaries

BACKGROUND: Topical application of inhibitors of HMGCoA reductase, the rate-limiting enzyme of cholesterol synthesis, has been shown to induce impairment of barrier function. OBJECTIVE: Assessing whether oral administration of statins used for reducing blood levels of cholesterol induces functional changes in stratum corneum barrier. MATERIALS AND METHODS: 69 subjects of both sexes under-going treatment for hypercholesterolemia (mean age 48 +/- 11 years) entered the study; 43 had been treated with simvastatin and 11 with pravastatin for 6 months; 15 only on dietary regimen served as controls. Efficiency of stratum corneum water barrier was evaluated by transepidermal water loss (TEWL) measurement using an evaporimeter; water-holding capacity of the stratum corneum was assessed by the sorption-desorption test measured by capacitance. Statistical analysis was performed using ANOVA. RESULTS: No differences were found between the groups (simvastatin, pravastatin, diet) concerning both basal TEWL and the dynamic of water binding in the stratum corneum. CONCLUSIONS: Prolonged treatment with cholesterol-lowering drugs based on inhibition of HMGCoA reductase does not alter the permeability barrier of the skin.     

Über den Einfluß eines örtlich veränderlichen Reibwertes auf die Berechnung der Kräfte bei technischen Umformverfahren

Erfassung der Randschubspannung zwischen Werkzeug und Werkstück durch die Einführung eines veränderlichen Reibwertes. Abhängigkeit des Reibwertes von Druck, (Relativ-Geschwindigkeit und Temperatur aus vorliegenden physikalischen Untersuchungen der Reibverhältnisse; Reibgesetze aus Auswertung des einschlägigen Schrifttums. Vergleich verschiedener Reibgesetze bei den Umformverfahren Ziehen, Bandwalzen und Stauchen mit Hilfe der elementaren Theorie. Folgerungen für die Anwendung eines örtlich veränderlichen Reibwertes bei der Berechnung plastischer Umformvorgänge.     

Moderne Fertighäuser aus Holz und Holzwerkstoffen

Summary The number of prefabricated wooden houses manufactured in the Federal Republic of Germany cannot be seen from the statistics of building constructions, as the building material is not defined in the term “prefabricated houses”. Usually the number of one-family houses serves as a means for counting the number of all prefabricated wooden houses. Historical timber constructions initiated modern methods of prefabrication: the grid dimension stems from framework constructions, the construction design of wall components dates from skeleton constructions. As regards prefabricated houses different types of constructions can be distinguished according to the stage of prefabrication. The stage of prefabrication, the flexibility and free choice of design permit to compare these types of constructions. In conclusion, future trends of development are discussed.

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Moderne Fertigh?user aus Holz und Holzwerkstoffen Erste Mitteilung: Stand der Technik

Zusammenfassung Aus der Hochbaustatistik kann die Zahl der in der Bundesrepublik hergestellten Fertigh?user aus Holz nicht entnommen werden, da in der Definition für das „Fertigteilbaus” die Art der Baustoffe nicht festgelegt ist. Man behilft sich meist damit, da? man die Zahl der Einfamilienh?user als Ma? für die Zahl aller Fertigh?user aus Holz verwendet. Historische Bauarten von Holzh?usern lieferten Anregungen für die heute üblichen Bauarten von Fertigh?usern: von der Fachwerkbauweise stammt das Rasterma?, von der Gerippebauweise der konstruktive Aufbau der Wandelemente. Bei Fertigh?usern kann man je nach dem Grad der Vorfertigung verschiedene Bauarten unterscheiden. Ein Vergleich dieser Bauarten ist nach dem Grad der Vorfertigung, der Mobilit?t und der Freiheit in der Grundri?gestaltung m?glich. Abschlie?end werden Entwicklungstendenzen genannt.

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Mitteilung aus dem Institut für Holzforschung und Holztechnik der Universit?t München     

Personal orchestra: a real-time audio/video system for interactive conducting

We present the first multimedia system to conduct a realistic electronic orchestra. Users can control tempo, dynamics, and instrument emphasis of the orchestra through natural conducting gestures with an infrared baton. Using gesture recognition and tempo adjustment algorithms, the system plays back an audio and video recording of an actual orchestra that follows the users conducting in real time. A major achievement of this system is its ability to vary playback speed in real time while avoiding audio artifacts such as pitch changes. The system has been deployed as an exhibit and has become a major attraction of a large Vienna-based music exhibition center.An erratum to this article can be found at