On the extended binomial distribution

An Extended Binomial random variable tallies the number of successes in n dichotomous and independent experiments with unequal probability of success in each trial, however. The paper describes situations where an Extended Binomial distribution arises and suggests an algorithm for computing its values.     

On the analysis and solution of certain geographical optimal covering problems

The article formulates, analyses and suggests solutions to some optimal covering problems that often arise in association with geographical coordinates, albeit their mathematical form may be detached from this background. It shows that under a general formulation no favorable mathematical properties can be deduced beyond the “center of gravity”, and thus that computational algorithms are seemingly the best resort for resolving the problem. An algorithm that is based on the steepest descent approach and that exploits the “center of gravity” property is devised, and is shown as a detector of local minima points. A release from the “locality trap” is provided by a stochastic algorithm.Every part of the paper is accompanied by illustrative examples, either of an analytical nature on a segment of the real line or of a numerical nature by computer programs.     

Topochemistry. Part XXXIX. The Solid-state Photochemistry of some 2′-Nitrochalcones

It is shown that the specific pathway of a complex photochemical reaction in the solid state is governed by the molecular conformation and its retention, and by the molecular packing. 2′-Nitrochalcone and those of its derivatives which are isomorphous with it display the s-trans conformation in the solid state and yield indigos upon irradiation. However, this conformation is not sufficient to ensure photoreactivity: thus the s-trans-4-bromo-derivative does not yield indigo. The same derivative in the s-cis conformation (in a second crystal form) has a crystal structure similar to that of the parent compound, and also does not yield indigo.     

A study of machine-level software profile

The instruction mix of a CDC CYBER/74 computer in a university environment was monitored, and in this paper frequencies of execution for the most commonly used instructions are given. From these measurements we make a number of observations about several aspects of computing patterns. One observation is the fact that if we exclude the idle loop of the operating system, the percentage of occurrences for each type of instruction over various time intervals is constant. This fact is used to define a machine-level software profile (MLSP) for the type of machine operations in the given computing environment. It is shown that the MLSP could be used to find machine utilization and the extent to which software takes advantage of machine architecture, and as a consistent method to improve the performance of a machine configuration.     

Control design for suppressing transversal patterns in reaction–(convection)–diffusion systems

The stabilization of planar stationary fronts solutions in a two-dimensional rectangular or cylinder domain, in which a diffusion–convection–reaction process occurs, is studied by reducing the original two-variable PDEs model to an approximate one-dimensional model that describes the behavior of the front line. We consider the control strategy based on sensors placed at the designed front line position and actuators that are spatially-uniform or space dependent. We present a systematic control design that determines the number of required sensors and actuators, their position and their form. The control used linear analysis of a lumped truncated model and concepts of finite and infinite zeros of linear multidimensional systems.     

Correlates of employee lateness: Some theoretical considerations.

Using hypothesis-driven meta-analytic procedures on 30 samples containing 118 correlations, researchers examined competing models of the relationship between lateness and assorted work-related variables. Consistent with a progression withdrawal model, the mean corrected lateness-absence correlation, .40, was found to be higher than the lateness-turnover correlation, .27. Hypotheses regarding the relationships between lateness and attitudes, performance, and demographics were generally supported. Methodological issues, including the need for longitudinal designs in the field and the inclusion of other moderators such as organizational and personality variables, were discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A note on lossless database decompositions

It is known that under a wide variety of assumptions a database decomposition is lossless if and only if the database scheme has a lossless join. Biskup, Dayal and Bernstein (1979) have shown that when the given dependencies are functional, the database scheme has a lossless join if and only if one of the relation schemes is a key for the universal scheme. In this note we supply an alternative proof of that characterization. The proof uses tools from the theory of embedded join dependencies and the theory of tuple and equality generating dependencies, but is, nevertheless, much simpler than the previously published proof.     

Thermal energy storage in columns packed with crosslinked polyethylene tubes

An energy storage system based on solid-solid phase transition of crosslinked polyethylene was constructed and tested. The energy storage unit consisted of a column packed with crosslinked polyethylene tubes. The solid-solid phase transition enables heat transfer by direct contact between the form-stable polymer and the hot (cold) fluid. A theoretical model for the simulation of this system was developed. The heating-cooling characteristics of the energy storage system were simulated by the model, using measured thermodynamic properties of the crosslinked polyethylene. The potential of various crosslinked polyethylene materials for energy storage applications will depend on sufficient high-temperature stability.