An O(n) algorithm for the linear multiple choice knapsack problem and related problems

We present an O(n) algorithm for the Linear Multiple Choice Knapsack Problem and its d-dimensional generalization which is based on Megiddo's (1982) algorithm for linear programming. We also consider a certain type of convex programming problems which are common in geometric location models. An application of the linear case is an O(n) algorithm for finding a least distance hyperplane in R^d according to the rectilinear norm. The best previously available algorithm for this problem was an O(n log²n) algorithm for the two-dimensional case. A simple application of the nonlinear case is an O(n) algorithm for finding the point at which a ‘pursuer’ minimizes its distance from the furthest among n ‘targets’, when the trajectories involved are straight lines in R^d.     

Environmental effects on deformation,strength, and degradation of unidirectional glass-fiber reinforced plastics. II. Experimental study

Glass-fiber reinforced epoxy (GRP) and unfilled epoxy specimens were exposed to different environmental conditions consisting of hot- and cold-water absorption and subsequent drying. Effects of the environmental history on deformational and strength characteristics of the composite material were investigated. GRP specimens exposed to hot water undergo pronounced degradation, which sets in shortly after exposure and is associated with a significant irrecoverable weight loss. Degraded specimens are characterized by higher void content and lower strength compared with their cold-water and reference counterparts. The degradation process is attributed to penetration of water into the matrix-fiber interfaces and is followed by an attack, at high temperatures, on the glass-fibers surface and coupling agent. As a result, glass constituents are leached out and then removed from the system by diffusion. The degradation effect was also confirmed by micro-observation of the fractured surfaces and by infra-red spectroscopy. A simple and effective testing method is recommended, permitting detection of degradation onset and its progress by simultaneous measurement of weight and dimensional changes with time.     

Coping dimensions, life stress, and adolescent substance use: A latent growth analysis.

The relation of seven coping dimensions to substance (tobacco, alcohol, marijuana) use was tested with a sample of 1,668 participants assessed at mean age 12.5 years and two yearly follow-ups. An associative latent-growth model showed one index of engagement (behavioral coping) to be inversely related to initial level of adolescent use and growth over time in peer use. Three indices of disengagement (anger coping, helpless coping, and hangout coping) were positively related to initial levels of peer use and adolescent use and to growth in adolescent use. Moderation tests indicated that effects of coping were significantly greater at higher level of stress; behavioral coping buffered the effects of disengagement. Effects of life stress were greater for girls than boys. Results are discussed with reference to mechanisms of coping-substance use relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Scaling of the Shaped Charge Jet Break‐Up Time

Since the formula for the shaped charge jet break‐up time was published on 1979 many attempts were made to interpret it and to make its use more efficient. It is shown herein that the V_pl parameter depends on the ratio of the liner thickness to the charge explosive diameter by the formula: 1/V_pl=13.9−101⋅(T_L/CD), where T_L is the liner thickness, CD is the explosive charge diameter and the numbers are for a published set of measurements with an OFE copper liner driven by COMP‐B explosive. To find how the numbers used in this formula change with the liner material and its metallurgical state and with the type of explosive, measurements should be made as prescribed herein. An attempt to begin explaining this formula is made in the discussion.     

Fundamental chemistry and engineering aspects of post-treatment processes for desalinated water—A review

The quality with which water is released from desalination plants is continuously increasing. Since desalination permeates are slightly acidic, contain very low buffering capacity and are very soft, post-treatment is always required. This paper reviews the knowledge accumulated in the last decades on desalination post-treatment processes. It covers fundamental chemistry aspects, required water quality criteria, advantages and disadvantages of currently applied processes, engineering and cost considerations, recent full-scale project experience and up-to-date research trends.     

Laser-Based Printing: From Liquids to Microstructures

Assembly of materials into microstructures under laser guidance is attracting wide attention. The ability to pattern various materials and form 2D and 3D structures with micron/sub-micron resolution and less energy and material waste compared with standard top-down methods make laser-based printing promising for many applications, for example medical devices, sensors, and microelectronics. Assembly from liquids provides a smaller feature size than powders and has advantages over other states of matter in terms of relatively simple setup, easy handling, and recycling. However, the simplicity of the setup conceals a variety of underlying mechanisms, which cannot be identified simply according to the starting or resulting materials. This progress report surveys the various mechanisms according to the source of the material—preformed or locally synthesized. Within each category, methods are defined according to the driving force of material deposition. The advantages and limitations of each method are critically discussed, and the methods are compared, shedding light on future directions and developments required to advance this field.     

A survey of the automorphism groups of some fulleroids

An automorphism of the graph X is a bijection on which preserves the edge set. By a (x,6) fullerene graph, we mean a fulleroid graph composed of x-gonal and hexagonal faces which satisfies in the Euler's theorem. The aim of this paper is to report the automorphism group of some fulleroid graphs such as fullerene graphs. We also determine the size of automorphism group of some fullerenes.