An X-ray diffraction study of defect parameters in a Ti-base alloy

Detailed studies based on the well established method of Fourier line shape analysis have been made on the X-ray diffraction profile of hexagonal titanium alloy of nominal composition Ti-6.58% Al-3.16% Mo-1.81% Zr-008% Fe-0.012% N-0.0078% C. While deformation fault probability, α, has been found to be quite high compared to that of pure titanium, the deformation growth fault parameter, β, shows a negative value ruling out the presence of growth fault in this alloy in the deformed state.     

Utility based service differentiation in CDMA data networks

The wireless data services are getting more and more competitive because of the presence of multiple service providers, all of whom offer some relative advantages and flexibilities over the others. As a result, the user churn behavior (i.e., migration from one service provider to another) is causing tremendous revenue loss for the service providers and also failure of existing resource management algorithms to fully capture the impact of churning. Moreover, the quality of service (QoS) offered to users belonging to different classes calls for new resource management schemes that address the issues related to differentiated services. In this paper, we propose a framework to study the impact of user churn behavior on the resource management algorithms to provide class-based differentiated services in CDMA data networks. In particular, our framework incorporates the user churning behavior into the admission control and power management algorithms, so that the service provider’s revenue loss due to churn can be minimized. Since optimal rate/power allocation in multi-rate CDMA systems is in general NP-Complete, we provide heuristics that try to provide solutions to the resource allocation problem in real-time. In our proposed framework, we add another layer of power management called Class-Based Power Allocation/Reduction (CBPAR) function, which works with the rate control algorithm to achieve power allocation. With CBPAR, the number of variables of the optimization problem is significantly reduced helping achieve the results in real-time. Our simulation study shows that the service provider’s revenue can be improved with the help of CBPAR framework. It also reveals the relationship between users’ sensitivity and tolerance to QoS degradation and optimal power allocations. Haitao Lin received his PhD in Computer Science and Engineering from the University of Texas at Arlington in 2004. He received his B.E. degree in Radio Engineering from Southeast University, Nanjing, China, in 1996 and the MS degree in Computer Applications from the Beijing University of Posts and Telecommunications, Beijing, China, in 2000. He is currently with Converged Multimedia Networks (CMN) Systems Engineering at Nortel, Richardson, Texas. His research interests include wireless network performance evaluation and enhancement, wireless link adaptation, wireless network resource management, applied game theory, network overload control performance modeling and analysis. Mainak Chatterjee received his Ph.D. from the department of Computer Science and Engineering at The University of Texas at Arlington in 2002. Prior to that, he completed his B.Sc. with Physics (Hons) from the University of Calcutta in 1994 and M.E. in Electrical Communication Engineering from the Indian Institute of Science, Bangalore, in 1998. He is currently an Assistant Professor in the department of Electrical and Computer Engineering at the University of Central Florida. His research interests include economic issues in wireless networks, applied game theory, resource management and quality-of-service provisioning, ad hoc and sensor networks, CDMA data networking, and link layer protocols. He serves on the executive and technical program committee of several international conferences. Sajal K. Das received the BTech degree in 1983 from Calcutta University, the MS degree in 1984 from the Indian Institute of Science, Bangalore, and the PhD degree in 1988 from the University of Central Florida, Orlando, all in computer science. Prior to 1999, he was a professor of computer science at the University of North Texas, where he twice (in 1991 and 1997) received the Student Associationís Honor Professor Award for best teaching and scholarly research. Currently, he is a professor of computer science and engineering and also the founding director of the Center for Research in Wireless Mobility and Networking (CReWMaN) at the University of Texas at Arlington (UTA). His current research interests include resource and mobility management in wireless and sensor networks, mobile and pervasive computing, wireless multimedia and QoS provisioning, mobile Internet protocols, distributed processing, and grid computing. He has published more than 350 research papers, directed numerous funded projects, and holds five US patents in wireless mobile networks. He received the Best Paper Award in ACM MobiComí99, ICOINí01, ACM MSWIMí00, and ACM/IEEE PADSí97. He was also a recipient of UTAís Outstanding Faculty Research Award in Computer Science in 2001 and 2003, and UTAís College of Engineering Excellence in Research Award in 2003. He is the coauthor of a book Smart Environments: Technology, Protocols and Applications, published in 2004 by John Wiley. Dr. Das is the editor-in-chief of the Pervasive and Mobile Computing journal and serves on the editorial Boards of four international journals, including IEEE Transactions on Mobile Computing and ACM/Kluwer Wireless Networks. He has served as general chair of IEEE WoWMoMí05, IWDCí04, IEEE PerComí04, CITí03, and IEEE MASCOTSí02; general vice chair of IEEE PerComí03, ACM Mobi- Comí00, and HiPCí00-01; program chair of IWDCí02 and WoWMoMí98-99; TPC vice chair of CITí05 and ICPADSí02; and as TPC member of numerous IEEE and ACM conferences. He is the vice chair of IEEE Technical Committees (TCPP and TCCC) and on the Advisory Boards of several cutting-edge companies. He is a member of the IEEE Computer Society.     

Parallel computation of 3-D electromagnetic scattering using finite elements

The finite element method (FEM) with local absorbing boundary conditions has been recently applied to compute electromagnetic scattering from large 3-D geometries. In this paper, we present details pertaining to code implementation and optimization. Various types of sparse matrix storage schemes are discussed and their performance is examined in terms of vectorization and net storage requirements. The system of linear equations is solved using a preconditioned biconjugate gradient (BCG) algorithm and a fairly detailed study of existing point and block preconditioners (diagonal and incomplete LU) is carried out. A modified ILU preconditioning scheme is also introducted which works better than the traditional version for our matrix systems. The parallelization of the iterative sparse solver and the matrix generation/assembly as implemented on the KSR1 multiprocessor is described and the interprocessor communication patterns are analysed in detail. Near-linear speed-up is obtained for both the iterative solver and the matrix generation/assembly phases. Results are presented for a problem having 224,476 unknowns and validated by comparison with measured data.     

Leadership in Innovators and Defenders: The Role of Cognitive Personality Styles

This research is based on a mixed strategic typology, combining innovators of Miller and Roth (1994, “A Taxonomy of Manufacturing Strategies,” Management Science, 40 (3), 285–304) and defenders of Miles et al. (1978, “Organizational Strategy, Structure and Process,” Academy of Management Review, 3, 546–562) and supported by the perception–evaluation personality model of Jung (1923, Psychological Types, London, Routledge & Kegan). Leadership model having five underlying constructs—group cohesion, intellectual flexibility, leader cognitive styles, leadership styles and leadership roles—is identified and studied. At first, respondent firms from various sectors are classified as innovators and defenders. Second, the constructs are empirically tested on them. Important findings suggest that innovators have intuitive-feeling leaders and defenders have sensing-thinking leaders, two of the four personality types proposed by Jung (1923). It has also been found that innovators are higher in the degree of intellectual adjustment; in the idea generation and nurturant phase leaders exhibit intuitive-feeling personality style; concept creators also exhibit the same. These findings may be used in organizations for leadership building, finding out best candidate job-fit and organization-fit during recruitment, and also for training and development of the leaders.     

Preparation and ac electrical characterizations of Cd doped SnO2 nanoparticles

Nanoparticles (NPs) of the Sn_1?xCd_xO₂ (0.0 ≤ x ≤ 0.04) were synthesized through soft chemistry method. These NPs were characterized for structural, morphological and electrical properties by X-ray diffraction, High resolution transmission electron microscopy and dielectric spectroscopy techniques respectively. Structural analysis confirms that all the NPs are having single phase rutile tetragonal structure. The NPs are of spherical shape and average size of these is found to decrease with Cd doping. Dielectric permittivity and AC conductivity of all the NPs were evaluated as a function of frequency and composition at room temperature. The frequency response of ε_r, ε_i, tan δ and σ _ac show that the dispersion is due to the interfacial polarization and these parameters decrease with doping of Cd in the SnO₂ matrix. The possible correlation between observed dielectric properties and size of NPs, and hence disorder in the system are explored.     

Estimation of bending of micromachined gold cantilever due to residual stress

Electroplated gold is widely used as the material for the micromachined beam structures due to its excellent electrical and mechanical properties. This work attempts to analyze the surface micromachined gold cantilever beams under inherently present stress gradient. The structure is analyzed by using finite element method simulation at different intrinsic stress gradients. The gold layers are deposited using cyanide electroplating bath operated at different current densities. Residual stresses in electroplated gold layers deposited on photoresist coated silicon samples are estimated by using X-ray diffraction technique. Cantilever beam structures are fabricated using surface micromachining technique. The tip deflections of the fabricated cantilever beams are found to be ~16 and 8 μm corresponding to the 1.0 and 0.7 mA/cm² current densities (mean), respectively. The corresponding intrinsic stress gradients are estimated to be ?13.9 and ?7.2 MPa/μm, respectively. Simulated and measured values of residual stresses are well matched.     

Reduction of Nickel Oxide Powder and Pellet by Hydrogen

Reduction of nickel oxide (NiO) powder and pellet by hydrogen was studied in a thermogravimetric apparatus. The variables studied were temperature (573, 673, 773, 873, 973?K) and hydrogen flow rate (100, 150, 200?cc?min^?1). With NiO powder 70?C80?% reduction and with NiO pellets about 95?% reduction were achieved. With both NiO powder and pellets, the rate of reduction increased with increasing temperature and hydrogen flow rate and the linear nature of the fractional reduction versus time (F vs. t) plot, for the most part of the reduction at all temperatures, supported a rate control by gas film diffusion. The activation energies for the reduction of NiO powder and NiO pellet were found to be 20.14 and 19.21?kJ?mol^?1, respectively. The SEM images showed that the grain size of nickel (Ni) produced was 1?C2???, and the XRD analysis established the presence of Ni (and the absence of NiO) in the reduced sample.     

Impact of grade separator on pedestrian risk taking behavior

Pedestrians on Delhi roads are often exposed to high risks. This is because the basic needs of pedestrians are not recognized as a part of the urban transport infrastructure improvement projects in Delhi. Rather, an ever increasing number of cars and motorized two-wheelers encourage the construction of large numbers of flyovers/grade separators to facilitate signal free movement for motorized vehicles, exposing pedestrians to greater risk. This paper describes the statistical analysis of pedestrian risk taking behavior while crossing the road, before and after the construction of a grade separator at an intersection of Delhi. A significant number of pedestrians are willing to take risks in both before and after situations. The results indicate that absence of signals make pedestrians behave independently, leading to increased variability in their risk taking behavior. Variability in the speeds of all categories of vehicles has increased after the construction of grade separators. After the construction of the grade separator, the waiting time of pedestrians at the starting point of crossing has increased and the correlation between waiting times and gaps accepted by pedestrians show that after certain time of waiting, pedestrians become impatient and accepts smaller gap size to cross the road. A Logistic regression model is fitted by assuming that the probability of road crossing by pedestrians depends on the gap size (in s) between pedestrian and conflicting vehicles, sex, age, type of pedestrians (single or in a group) and type of conflicting vehicles. The results of Logistic regression explained that before the construction of the grade separator the probability of road crossing by the pedestrian depends on only the gap size parameter; however after the construction of the grade separator, other parameters become significant in determining pedestrian risk taking behavior.     

A profit maximising product line optimisation model under monopolistic competition

Existing research on product line optimisation have focused mainly on designing a product line based on the trade-offs between sellers’ and buyers’ utility, without any explicit consideration of the underlying market structure. A few studies can be found that consider the monopolists’ optimal product line offering. In this study, we examine the optimal product line decision of an entrant firm under monopolistic competitive markets. Specifically, we develop a mathematical programming formulation of an entrant firm’s problem of deciding on the market segments to enter and the corresponding product designs to offer, to maximise its profit. A heuristic has been presented for solving the resulting mixed integer non-linear programming problem. The specifications of the problem increase exponentially with the size of the problem and as such, commercial solvers are not useful for solving a generalised instance. A small example has been presented and solved using both the heuristic and the ILOG CPLEX 10.2. Both result in identical solutions. We attempt an explanation on why the heuristic gives an optimal solution.     

Prediction of electrical resistivity of steel using artificial neural network

Electrical resistivity of commercially produced plain carbon manganese steel has been experimentally measured at room temperature (28–30°C) using four-probe method. Resulting data were used to generate both regression based and artificial neural network-based models for prediction of electrical resistivity from the chemical composition of steel. It was found that both models were capable of predicting the resistivity within ±5% error band. Analysis of data also indicated carbon to be the most influential element to increase resistivity followed by manganese and silicon. A comprehensive literature review indicates no such advanced resistivity prediction model is available in the public literature for commercially produced steel with wide variation in carbon content (0.03?0.85?wt-%), manganese content (0.35–1.50?wt-%) and silicon content (0.015–0.90?wt-%).