Multirow joint fastener load investigation

A multirow joint subjected to the mechanical and thermal loadings was investigated to determine the loads taken by the fasteners in each row. The hole clearance was considered and its effect on the thermal expansion was defined. The friction in the interface between two plates in contact was analyzed and its effect on the distribution of fastener loads was determined. The primary joint design parameters, such as the material and size of the plates and of the fasteners and the patterns of fastener arrangement were considered. The principle of complementary virtual work was employed to derive the general equations involving these parameters, and the analytical solutions were obtained by solving the matrix equations. A computer program was developed to obtain the numerical solutions through the use of FORTRAN IV System 370/165 computer techniques. The application of the computer program to the practical joint design problems is discussed.     

Spin excitations of bitumens

Bitumen free radicals are located within the planar polynuclear aromatic ring systems of bituminous crystallites in such a manner as to optimize their stabilization by the resonance of delocalized π-electrons. The states of spin multiplicity exhibited by these substances are revealed by the observed transitions under thermal excitations. Experimental ESR intensity-temperature dependence data from several asphaltic bitumens, a model compound (phthalocyanine), and a few charge-transfer complexes were collected. Curves containing both exponential (singlet-triplet) and Curie-Weiss (doublet) components were then calculated from the curves and found to be consistent with published results. This spin correlation indicates that both singlet-triplet transitions and doublet states exist within the bituminous aromatic sheets. This and other forms of thermal excitation (e.g., Russell effect), may be attributed to the propagation of Wannier excitons. The predominance of doublet concentrations in high vanadium samples (e.g., Mara asphaltene) indicates that spins are localized by nuclei-spin interactions.     

Influence of texture on the analysis of thermoelastic/plastic anisotropy and the initial yielding of zircaloy tubes

Averaging procedures are developed to obtain texture factors relating the thermoelastic properties of single crystals of zirconium to polycrystalline properties. The effect of various approximations to the elastic properties of poly crystalline material and various assumed yield criteria on the transition from elastic to plastic behavior for a tube subjected to various boundary conditions is examined. It is found that thermal anisotropy has a greater effect on the elastic-plastic transition than does elastic anisotropy. The choice of yield condition can also affect appreciably the predicted yielding behavior of a tube.     

Preference update for e-commerce applications: Model,language, and processing

It is likely that customers issue requests based on out-of-date information in e-commerce application systems. Hence, the transaction failure rates would increase greatly. In this paper, we present a preference update model to address this problem. A preference update is an extended SQL update statement where a user can request the desired number of target data items by specifying multiple preferences. Moreover, the preference update allows easy extraction of criteria from a set of concurrent requests and, hence, optimal decisions for the data assignments can be made. We propose a group evaluation strategy for preference update processing in a multidatabase environment. The experimental results show that the group evaluation can effectively increase the customer satisfaction level with acceptable cost. Peng Li is the Chief Software Architect of didiom LLC. Before that, he was a visiting assistant professor of computer science department in Western Kentucky University. He received his Ph.D. degree of computer science from the University of Texas at Dallas. He also holds a B.Sc. and M.S. in Computer Science from the Renmin University of China. His research interests include database systems, database security, transaction processing, distributed and Internet computer and E-commerce. Manghui Tu received a Bachelor degree of Science from Wuhan University, P.R. China in 1996, and a Master Degree in Computer Science from the University of Texas at Dallas 2001. He is currently working toward the PhD degree in the Department of Computer Science at the University of Texas at Dallas. Mr. Tu’s research interests include distributed systems, grid computing, information security, mobile computing, and scientific computing. His PhD research work focus on the data management in secure and high performance data grid. He is a student member of the IEEE. I-Ling Yen received her BS degree from Tsing-Hua University, Taiwan, and her MS and PhD degrees in Computer Science from the University of Houston. She is currently an Associate Professor of Computer Science at the University of Texas at Dallas. Dr. Yen’s research interests include fault-tolerant computing, security systems and algorithms, distributed systems, Internet technologies, E-commerce, and self-stabilizing systems. She had published over 100 technical papers in these research areas and received many research awards from NSF, DOD, NASA, and several industry companies. She has served as Program Committee member for many conferences and Program Chair/Co-Chair for the IEEE Symposium on Application-Specific Software and System Engineering & Technology, IEEE High Assurance Systems Engineering Symposium, IEEE International Computer Software and Applications Conference, and IEEE International Symposium on Autonomous Decentralized Systems. She is a member of the IEEE. Zhonghang Xia received the B.S. degree in applied mathematics from Dalian University of Technology in 1990, the M.S. degree in Operations Research from Qufu Normal University in 1993, and the Ph.D. degree in computer science from the University of Texas at Dallas in 2004. He is now an assistant professor in the Department of Computer Science, Western Kentucky University, Bowling Green, KY. His research interests are in the area of multimedia computing and networking, distributed systems, and data mining.     

Preparation and characterization of poly(o-phenylenediamine) microrods using ferric chloride as an oxidant

Microrods of poly(o-phenylenediamine) (PoPD) were synthesized by a templateless method using ferric chloride as an oxidant. The microrod morphologies of the resulting PoPD were confirmed by scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images. When the concentration of o-phenylenediamine (oPD) was 0.03 M, the microrods of PoPD had a diameter in the range of 0.5-2 μm and a length from 2 μm to 20 μm. It was found that the concentration of oPD monomer had much influence on the morphology of the obtained PoPD. When the concentration of oPD was lower than 0.03 M, long microrods could be observed. However, when the concentration of oPD monomer was higher than 0.12 M, the length of the microrods became very short and the diameter became bigger. Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectra and X-ray diffraction (XRD) were used to characterize the structure of the obtained PoPD microrods.     

Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples

The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu₆Sn₅ phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au quaternary system. Three IMCs, AuSn, AuSn₂, and AuSn₄, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)₆Sn₅ phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended and the Cu content of the alloy was increased, the AuSn₄ phase disappeared gradually. The (Au, Cu)Sn and (Cu_,Au)₆Sn₅ layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems.     

Toward a hybrid model for usability resource allocation in industrial software product development

The organizational aspects of user‐centered software development in a financial services company are presented. The financial services industry sector is one of the industrial sectors to embark on the development of computer software as a consumer product. The nature of business in the service sector predisposes it to encounter difficulties in developing software aimed at meeting customer demands. Lack of familiarity and experience with the product design and implementation processes, as well as reliance on usability for acceptance, are major obstacles encountered. Difficulties, insights, and lessons learned regarding organizational ergonomics issues faced by a user‐centered design group are provided, and a hybrid resource distribution model is proposed to guide other service sector companies in their future software development efforts. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 245–262, 2007.     

Coding behavior of authentication code on the internet

With the rapid growth of Internet services, virtual world has witnessed an increasingly large number of online users who have a variety of needs such as accessing various websites to gather information, easing business transactions, and sharing updates. As a result, information security has become a major concern among online users, and the verification of access codes is now the main practice used to keep information systems safe. However, some issues arise as the result of coding and managing behavior, and this research seeks to address these issues. After following the Focus Group method and interviewing 13 college students, this research finds that forgetting the access code is one of the biggest challenges to most online users simply because of the longer duration and the time when the users have a need to access the websites again, their memory will eclipse. In addition, online users usually develop self-constructed rules to cope with elusive code. These rules include: creating some sets of code that may not be meaningful to outsiders; taking different degrees of complex measures to register authentication codes, dependent upon the importance of the websites to the online users; writing the authentication codes on a scratchpad and sticking it on the computer screen; and keeping the codes in a notebook or computer file. The above practices nevertheless run the risk of being usurped by hackers, and it is found that hacking frequently takes place among closest friends, as they are quite familiar with the coding behavior of the victims. While assisting coding management does not help in this regard, as it is generally too expensive, online users troubled by the forgetting of access codes often end up with re-applying for a new set of authentication codes after unsuccessfully trying to login. All these self-constructed rules, nevertheless, constitute threat to information security. The research, in conclusion, calls for an education campaign to promote healthy coding behavior and effective coding management. The obtained findings provide valuable references for both academicians and practitioners to understand the online users’ coding behaviors and to effectively manage them accordingly to improve the resulting information security.