Hypoelastic,hyperelastic, discrete and semi-discrete approaches for textile composite reinforcement forming

The clear multi-scale structure of composite textile reinforcements leads to develop continuous and discrete approaches for their forming simulations. In this paper two continuous modelling respectively based on a hypoelastic and hyperelastic constitutive model are presented. A discrete approach is also considered in which each yarn is modelled by shell finite elements and where the contact with friction and possible sliding between the yarns are taken into account. Finally the semi-discrete approach is presented in which the shell finite element interpolation involves continuity of the displacement field but where the internal virtual work is obtained as the sum of tension, in-plane shear and bending ones of all the woven unit cells within the element. The advantages and drawbacks of the different approaches are discussed.     

An electronic museum guide in real use.

Within the Contextual Model of Learning framework, the authors conducted a study with electronic handheld guides at the Van Abbe Museum. The authors offered the general electronic tour using the ubiNext system for the duration of two weeks. This study investigated whether the use of multimedia content would increase the usage of the system compared to only visual content. In addition the authors were interested if the age of the visitors would influence the system's usage. The authors also investigated whether individual visitors use the system more compared to visitors who experience the museum in couples. More than half of the visitors only requested information for five or less objects independently of the visitor's age. Technical problems and usability issues might have caused many visitors to stop using ubiNext. Among those participants who heavily used the system, the display of multimedia content led to an increased usage compared to visual content only. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Crystal Quality and Surface Wettability of Various Tellurium-Based Chalcopyrite Layers Grown by the Closed Space Sublimation

AgGaTe₂, AgAlTe₂, CuGaTe₂, and Ag(Ga,Al)Te₂ layers were deposited by the close spaced sublimation method. The surface morphology and crystal quality of these Te-based chalcopyrite layers were systematically evaluated. Controlling the stoichiometry of these layers grown by the closed space sublimation was very difficult because Te preferentially detached from the source materials during the sublimation process and then Te vapor leaked out from the reactor. To solve this problem, the gap between the lid and reactor boat was minimized, and the vapor was encapsulated. As a result, the crystal quality of the AgGaTe₂ and AgAlTe₂ was improved. However, the controlling stoichiometry of CuGaTe₂ remained difficult even after the Te vapor leakage was minimized. This behavior was attributed to the large vapor pressure difference between Cu and Te. The surface morphology of the grown AgGaTe₂ and CuGaTe₂ layers exhibited scattered grain structure, while that of AgAlTe₂ possessed a continuous film structure. These different surface structures contributed to differing wettability between the chalcopyrite materials and substrates. It was found that AgAlTe₂ exhibited a high wettability against a sapphire substrate, which promoted continuous film formation.     

Chemical activity of oxygen atoms in the magnetron sputter-deposited ZnO films

The role of oxygen atoms in the growth of magnetron sputter-deposited ZnO films was studied by alternating the deposition of a several-nanometer-thick ZnO layer and an O₂/Ar mixed plasma exposure, i.e., a layer-by-layer (LbL) technique. The film crystallization was promoted by suppressing the oxygen vacancy and interstitial defects by adjusting the exposure conditions of the O₂/Ar plasma. These findings suggest that the chemical potential of the oxygen atom influences the film crystallization and the electronic state. The diffusion and effusion of oxygen atoms at the growing surface have an effect similar to that of thermal annealing, promoted film crystallization and the creation and the annihilation of oxygen- and zinc-related defects. The role of oxygen atoms reaching at the growing film surface is discussed in terms of chemical annealing and a possible oxygen diffusion mechanism is proposed.     

Complex wounds tend to develop more rapidly in patients receiving hemodialysis because of diabetes mellitus

The number of patients requiring dialysis because of diabetes mellitus is increasing and such patients often have complex chronic wounds, which are difficult to heal. However, there are few retrospective studies of wounds requiring surgical treatment. We evaluated 14 patients receiving hemodialysis (HD) (8 because of diabetes and 6 because of other diseases) who had extremity wounds and underwent surgical treatment in our unit from 2004 through 2007. We investigated differences in the cause of wounds, and in the interval between the start of HD and wound development. Wounds in patients undergoing HD because of diabetes originated due to ischemia in 2 cases (25%), trauma in 2 cases (25%), and infection in 4 cases (50%). Seven of 8 wounds developed infection with methicillin-resistant Staphylococcus aureus (MRSA). Wounds in patients undergoing HD because of other diseases developed due to ischemia in 2 cases (33%) and trauma in 4 cases (67%). Three of 6 wounds developed infection and MRSA were isolated from 2 wounds. The interval between the start of HD and wound development was significantly shorter in patients with diabetes than in patients without diabetes. All patients with infectious wounds required immediate debridement. We conclude that patients receiving HD because of diabetes are likely to have more severe and rapidly developing wounds due to infections. Thus, they usually require immediate debridement before blood access shunt infection occurs.     

MAGELLAN: Map Acquisition of GEographic Labels by Legend ANalysis

A system named MAGELLAN (denoting Map Acquisition of GEographic Labels by Legend ANalysis) is described that utilizes the symbolic knowledge found in the legend of the map to drive geographic symbol (or label) recognition. MAGELLAN first scans the geographic symbol layer(s) of the map. The legend of the map is located and segmented. The geographic symbols (i.e., labels) are identified, and their semantic meaning is attached. An initial training set library is constructed based on this information. The training set library is subsequently used to classify geographic symbols in input maps using statistical pattern recognition. User interaction is required at first to assist in constructing the training set library to account for variability in the symbols. The training set library is built dynamically by entering only instances that add information to it. MAGELLAN then proceeds to identify the geographic symbols in the input maps automatically. MAGELLAN can be fine-tuned by the user to suit specific needs. Recognition rates of over 93% were achieved in an experimental study on a large amount of data. Received January 5, 1998 / Revised March 18, 1998     

A Fuzzy AHP Approach to Evaluating Machine Tool Alternatives

Selecting process of a machine tool has been very important issue for companies for years, because the improper selection of a machine tool might cause of many problems affecting negatively on productivity, precision, flexibility and company’s responsive manufacturing capabilities. On the other hand, selecting the best machine tool from its increasing number of existing alternatives in market are multiple-criteria decision making (MCDM) problem in the presence of many quantitative and qualitative attributes. Therefore, in this paper, an analytic hierarchy process (AHP) is used for machine tool selection problem due to the fact that it has been widely used in evaluating various kinds of MCDM problems in both academic researches and practices. However, due to the vagueness and uncertainty on judgments of the decision-maker(s), the crisp pair wise comparison in the conventional AHP seems to insufficient and imprecise to capture the right judgments of decision-maker(s). That is why; fuzzy number logic is introduced in the pair wise comparison of AHP to make up for this deficiency in the conventional AHP. Shortly, in this study, an intelligent approach is proposed, where both techniques; fuzzy logic and AHP are come together, referred to as fuzzy AHP. First, the fuzzy AHP technique is used to weight the alternatives under multiple attributes; second Benefit/Cost (B/C) ratio analysis is carried out by using both the fuzzy AHP score and procurement cost, of each alternative. The alternative with highest B/C ratio is found out and called as the ultimate machine tool among others. In addition, a case study is also presented to make this approach more understandable for a decision-maker(s).     

Integrating symbolic images into a multimedia database system using classification and abstraction approaches

Symbolic images are composed of a finite set of symbols that have a semantic meaning. Examples of symbolic images include maps (where the semantic meaning of the symbols is given in the legend), engineering drawings, and floor plans. Two approaches for supporting queries on symbolic-image databases that are based on image content are studied. The classification approach preprocesses all symbolic images and attaches a semantic classification and an associated certainty factor to each object that it finds in the image. The abstraction approach describes each object in the symbolic image by using a vector consisting of the values of some of its features (e.g., shape, genus, etc.). The approaches differ in the way in which responses to queries are computed. In the classification approach, images are retrieved on the basis of whether or not they contain objects that have the same classification as the objects in the query. On the other hand, in the abstraction approach, retrieval is on the basis of similarity of feature vector values of these objects. Methods of integrating these two approaches into a relational multimedia database management system so that symbolic images can be stored and retrieved based on their content are described. Schema definitions and indices that support query specifications involving spatial as well as contextual constraints are presented. Spatial constraints may be based on both locational information (e.g., distance) and relational information (e.g., north of). Different strategies for image retrieval for a number of typical queries using these approaches are described. Estimated costs are derived for these strategies. Results are reported of a comparative study of the two approaches in terms of image insertion time, storage space, retrieval accuracy, and retrieval time. Received June 12, 1998 / Accepted October 13, 1998