POEMS: end-to-end performance design of large parallel adaptive computational systems

The POEMS project is creating an environment for end-to-end performance modeling of complex parallel and distributed systems, spanning the domains of application software, runtime and operating system software, and hardware architecture. Toward this end, the POEMS framework supports composition of component models from these different domains into an end-to-end system model. This composition can be specified using a generalized graph model of a parallel system, together with interface specifications that carry information about component behaviors and evaluation methods. The POEMS Specification Language compiler will generate an end-to-end system model automatically from such a specification. The components of the target system may be modeled using different modeling paradigms and at various levels of detail. Therefore, evaluation of a POEMS end-to-end system model may require a variety of evaluation tools including specialized equation solvers, queuing network solvers, and discrete event simulators. A single application representation based on static and dynamic task graphs serves as a common workload representation for all these modeling approaches. Sophisticated parallelizing compiler techniques allow this representation to be generated automatically for a given parallel program. POEMS includes a library of predefined analytical and simulation component models of the different domains and a knowledge base that describes performance properties of widely used algorithms. The paper provides an overview of the POEMS methodology and illustrates several of its key components. The modeling capabilities are demonstrated by predicting the performance of alternative configurations of Sweep3D, a benchmark for evaluating wavefront application technologies and high-performance, parallel architectures.     

Cybercrime: Understanding and addressing the concerns of stakeholders

Cybercrime and cybercriminal activities continue to impact communities as the steady growth of electronic information systems enables more online business. The collective views of sixty-six computer users and organizations, that have an exposure to cybercrime, were analyzed using concept analysis and mapping techniques in order to identify the major issues and areas of concern, and provide useful advice. The findings of the study show that a range of computing stakeholders have genuine concerns about the frequency of information security breaches and malware incursions (including the emergence of dangerous security and detection avoiding malware), the need for e-security awareness and education, the roles played by law and law enforcement, and the installation of current security software and systems. While not necessarily criminal in nature, some stakeholders also expressed deep concerns over the use of computers for cyberbullying, particularly where younger and school aged users are involved. The government’s future directions and recommendations for the technical and administrative management of cybercriminal activity were generally observed to be consistent with stakeholder concerns, with some users also taking practical steps to reduce cybercrime risks.     

Secure electronic markets for private information

Technological advances in the collection, storage, and analysis of data have increased the ease with which businesses can make profitable use of information about individuals. Some of this information is private, and individuals are simultaneously becoming more aware of the value of the information and how the loss of control over this information impacts their personal privacy. As a partial solution to these concerns, this paper presents a mechanism that serves two purposes. The first enables the use of private, numerical data in the answering of queries while simultaneously providing a security feature that protects the data owners from a loss of privacy that could result from an unauthorized access. The second develops a compensation model for the use of the data that allows individuals to dynamically redefine their security requirements. The compensation model is built on the information-security mechanism to create the foundation of a market for private information. This paper illustrates how compensation models like the one presented here could be used in a self-regulating market for private information. Additionally, the compensation component of an intermediated market for private information is developed and extensively analyzed. Finally, this paper provides insights and draws several important conclusions on markets for private information.     

The functions of aggression by male teenagers.

A selectionist theory states that violence by males toward male peers originally served specific functions and violence to female peers served others. Differences in self-reported victimization and perpetration in studies of 1,452 high school students were hypothesized. In Study 1, male-to-male aggression was reported to be more prevalent than male-to-female aggression. For male-to-male aggression, perpetrator reports agreed with or exceeded victim reports, and victims were more often strangers than close friends. In contrast, for male-to-female aggression, there were consistently fewer reports from perpetrators than from victims, and victims were less often strangers than girlfriends. Study 2 obtained similar findings for reported frequency, number of victims and perpetrators, and sexual aggression. Study 3 showed that girls' aggression contrasted with that by boys with respect to intra- versus intersex aggression and perpetrator–victim agreement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the optimality of two-stage state estimation in the presence ofrandom bias

Sufficient conditions for the optimality of a two-stage state estimator in the presence of random bias are derived. Under an algebraic constraint on the correlation between the state and bias process noises, the optimal estimate of the system state can be obtained as a linear combination of the output of the first stage (a bias-free filter) and the second stage (a bias filter). Because the algebraic constraint is restrictive in practice, the results indirectly indicate that for most practical systems the proposed solution to the two-stage estimation problem will be suboptimal     

MODELLING OF EMBEDDED FATIGUE CRACKS IN RAILROAD RAILS

Abstract— A first-generation fatigue crack growth model has been developed which realistically models the patterns of subsurface shells and detail fracture crack growth that are commonly observed in railroad rails. (These types of defects are further described in the Introduction.) The key assumptions upon which the model is based are reviewed and the input data on railroad rail residual stresses and wheel-induced stresses are described. Examples of the predicted growth patterns for shells and detail fractures are shown and compared to actually observed growth patterns. Apparent deficiencies in the model are discussed and probable avenues for improvement in the accuracy of the crack growth life estimates are identified.     

OBSERVATIONS ON THE FIRING OF A DOWNDRAFT KEN WITH A STOKER SITUATED OUTSIDE THEREOF1

This paper presents some observations that were made during a series of tests on round downdraft kilns fired with a single stoker, and shows the economies that can be expected with this method of firing and the disadvantages that must be overcome.     

Silver complexation in river waters of central New York

The dissolved component of the apparent silver complexation capacity was determined for Susquehanna and Chenango River water samples collected over a 3-month period in the vicinity of Binghamton, New York. Silver ion activities detected by the Ag⁺/S^2? ion selective electrode during potentiometric titration of the river water with AgNO₃ were lower than Ag⁺ activities calculated with an inorganic equilibrium speciation model. The maximum difference in Ag⁺ activity, which ranged from 1.5 × 10^?8 to 8.4 × 10^?8, was attributed to the presence of a constituent or constituents in the river water which strongly bind Ag, perhaps dissolved organic matter and/or colloidal material. Variation in apparent complexation capacity between river water samples was explained by different concentrations of the ligands complexing Ag. A tentative extrapolation of the dissolved Ag speciation to Ag concentrations in natural river water suggested that most of the Ag would be complexed by Cl^? and an unidentified constituent or constituents.