Application of the boundary integral method to the interaction of rising two-dimensional deformable gas bubbles

The boundary integral method is applied to model the initial motion of two-dimensional or cylindrical deformable gas bubbles in an inviscid, incompressible fluid. Following the success of recent boundary integral studies to predict the qualitative behaviour of a single gas bubble, this numerical study is extended to consider the interaction of several bubbles. Surface tension, relative initial position and volume are all found to be important factors affecting the bubble interaction, jet formation, trapping of fluid between bubbles and bubble shedding. As well as computing the evolution of the bubble surfaces, consideration of the pressure fields and resulting instantaneous streamlines is given.     

Psychosexual development of women with congenital adrenal hyperplasia

Women with congenital adrenal hyperplasia (CAH) (N = 31) and their unaffected sisters or female cousins (N = 15) participated in a study of psychosexual development. All participants were > or = 18 years of age (mean age, 25 years; range, 18-40). Comparisons were also made between the CAH women with the salt-wasting (SW) form of the disorder and those with simple virilization (SV). A psychosexual assessment protocol examined six variables: (1) sex assignment at birth (probands only); (2) recalled sex-typed behavior during childhood; (3) gender identity and gender role identification in adulthood; (4) relationship status; (5) sexual orientation in fantasy; and (6) sexual orientation in behavior. Salt-wasting status and sex assignment at birth were also ascertained for the CAH women who either refused to participate in the study (N = 10) or could not be traced (N = 13). Compared to the controls, the women with CAH recalled more cross-gender role behavior and less comfort with their sense of "femininity" during childhood. The two groups did not differ in degree of gender dysphoria in adulthood, although the probands showed more cross-gender role identification. Three of the nonparticipant probands were living, as adults, in the male social role (2 reared from birth as boys and 1 who changed from the female to the male social role during adolescence). The CAH women and the controls did not differ in relationship status (married/cohabiting vs. single). The CAH women had lower rates of exclusive heterosexual fantasy and fewer sexual experiences with men than the controls; however, the CAH women did not have more sexual experiences with women than the controls. Comparisons between the SW and SV revealed several differences: the SW were less likely to be assigned to the female sex at birth, recalled more cross-gender role behavior during childhood, were less likely to be married or cohabiting, and had lower rates of sexual experiences with men. The results were discussed in relation to the effects of prenatal androgens on psychosexual differentiation.     

Agent-mediated knowledge sharing for intelligent services management

For service-oriented architectures that span multiple businesses, organizations must transfer information back-and-forth about their available services. Because of the potential large volume, it is unreasonable and impractical to expect human practitioners to handle the scale of interactions desired and/or required on a continual basis. Intelligent agents offer the adaptability and flexibility to handle the knowledge transfer that must occur in order to share service offerings. Effectively transferring service-oriented information in this domain requires autonomous systems that adapt to heterogeneous environments. This work introduces an architecture and specialized communication procedures designed for this sort of knowledge sharing environment. We show that these procedures perform reasonably when evaluated with current agent communication technologies.

Probabilistic fusion of stereo with color and contrast for bilayer segmentation

This paper describes models and algorithms for the real-time segmentation of foreground from background layers in stereo video sequences. Automatic separation of layers from color/contrast or from stereo alone is known to be error-prone. Here, color, contrast, and stereo matching information are fused to infer layers accurately and efficiently. The first algorithm, layered dynamic programming (LDP), solves stereo in an extended six-state space that represents both foreground/background layers and occluded regions. The stereo-match likelihood is then fused with a contrast-sensitive color model that is learned on-the-fly and stereo disparities are obtained by dynamic programming. The second algorithm, layered graph cut (LGC), does not directly solve stereo. Instead, the stereo match likelihood is marginalized over disparities to evaluate foreground and background hypotheses and then fused with a contrast-sensitive color model like the one used in LDP. Segmentation is solved efficiently by ternary graph cut. Both algorithms are evaluated with respect to ground truth data and found to have similar performance, substantially better than either stereo or color/contrast alone. However, their characteristics with respect to computational efficiency are rather different. The algorithms are demonstrated in the application of background substitution and shown to give good quality composite video output.     

A comparison of behaviors and play themes over a six-week period: Two case studies in play therapy.

As a method for counseling children, play therapy continues to demonstrate effectiveness through research and to be included in mental health training programs throughout the country. However, like other counseling interventions, capturing the essence of the therapeutic environment is complex and dependent on individual perspectives and experiences. In this article, two case studies are presented to demonstrate the use of quantitative and qualitative measures in comparing the behavioral changes as rated by caregivers on the Child Behavior Checklist (CBCL) and play themes observed by play therapists over a 6-week period. For both children in the study, behaviors and themes were related. As the children made changes in their play themes over the 6-week period, they also made changes in their behaviors at home. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CONDENSATION—Conditional Density Propagation for Visual Tracking

The problem of tracking curves in dense visual clutter is challenging. Kalman filtering is inadequate because it is based on Gaussian densities which, being unimo dal, cannot represent simultaneous alternative hypotheses. The Condensation algorithm uses factored sampling, previously applied to the interpretation of static images, in which the probability distribution of possible interpretations is represented by a randomly generated set. Condensation uses learned dynamical models, together with visual observations, to propagate the random set over time. The result is highly robust tracking of agile motion. Notwithstanding the use of stochastic methods, the algorithm runs in near real-time.     

A simulation based supply partner selection decision support tool for service provision in Dell

Partner selection is an important aspect of all outsourcing processes. Traditional partner selection typically involves steps to determine the criteria for outsourcing, followed by a qualification of potential suppliers and concluding with a final selection of partner(s). Reverse auctions (RAs) have widely been used for partner selection in recent times. However, RAs, although proven successful in initial price reduction strategies for product and service provision, can suffer from reduced effectiveness as the number of executions increases.This paper illustrates Dell’s experience of such diminishing returns for its outsourced after sales product repair service and presents the development of a new partner selection methodology, which incorporates a new process improvement stage to be executed in combination with the final selection phase. This new methodology is underpinned by the development of a computer based simulation supply partner selection decision support tool for service provision. The paper highlights the significant additional cost saving benefits and improvement in service achievable through the use of advanced simulation based decision supports.     

Implications of failure criteria choices on the rapid concept design of composite grillage structures using multiobjective optimisation

Grillage topologies are commonly used in many composite structural applications to produce low mass designs that have a high stiffness. While composite failure criteria are being compared in many different simple structures, for example plates and tubes, literature must also compare more complicated applications, including grillages, as there are distinct differences in behaviour. This paper therefore performs analysis of grillage structures with more up to date failure criteria, taken from the world wide failure exercise, than previously investigated. The grillage theory selected is that of Navier theory with elastic equivalent properties due to its low computational expense for use with a genetic algorithm to optimise a composite structure. The results take an example from leisure boatbuilding showing the grillages produced from the different limit states, comparing the cost and mass. The final results show that the method allows a rapid analysis of grillages and that the selection of the limit state has an important effect on the optimised grillage topology.     

Global data and control in multicomputers: Operating system primitives and experimentation with a parallel branch-and-bound algorithm

The static distribution of work among tasks is not possible in many parallel applications. Therefore, it is essential to implement convenient and efficient abstractions for ‘work sharing’ on multicomputers. This paper compares the utility of two operating system facilities for the implementation of such ‘work sharing’: (1) a system for the migration of processes from heavily to less loaded processors and (2) a more general OS construct for the implementation of arbitrary distributed objects. Both were implemented as extensions to the Intel iPSC/1 operating system on a 32-node hypercube. Their experimental evaluation is based on a parallel implementation of a branch-and-bound algorithm. Two sets of results are attained. First, the necessity of the constructs for dynamic work sharing is demonstrated for applications with dynamic data domains, such as parallel branch-and-bound algorithms. This is followed by measurements that demonstrate the acceptable cost of process migration for a specific parallel branch-and-bound algorithm. These measurements are then compared with results attained with the construct for the implementation of distributed objects. Second, when using branch-and-bound to solve the Travelling Salesperson Problem (TSP), evaluation of the resulting parallel TSP program shows that some analytical and simulation results attained in past, published work may not hold.     

Soft Error Susceptibility of CMOS RAMS: Dependence upon Power Supply Voltage

Two types of a delidded CMOS 1024 × 1 RAM (Harris HM 6508-RH and Sandia TA597) have been tested for susceptibility to soft bit errors caused by 150-MeV krypton ions. Bit-error susceptibility was measured as a function of bias voltage and ion beam angle with respect to the chip-face normal. Comparison of measured bit-error rates and thresholds with those computed by use of a simple device model and manufacturer-supplied data shows good agreement in some respects while raising questions in others. In the case of the HM 6508-RH RAMs, measured values of critical charge of 1 pC and 2 pC at 5V and 7V, respectively, indicate that the devices can be expected to 4show bit-error rates in space of approximately 1 × 10-4 per chip per day at 5V bias and 1 × 10-5 per chip per day at 7V bias.