Electron beam irradiated HDPE/EVA/Mg(OH)2 composites for flame-retardant electric cables

The mechanical properties and flammability of high-density polyethylene (HDPE)/ethylene vinyl acetate (EVA) mixed with various amounts of magnesium hydroxide (Mg(OH)₂) as the filler in composites, irradiated with electron beam at an irradiation dose of 150 kGy, have been studied. It is found that high-energy electron beam irradiation has significant effects on the mechanical properties of the HDPE/EVA/Mg(OH)₂ composites. The tensile strength and elastic modulus increased greater than in the unirradiated ones. Meanwhile, with increasing the content of Mg(OH)₂ in the composites, the limiting oxygen index (LOI) value increased sharply. The microstructure of the caves of the unirradiated HDPE/EVA/Mg(OH)₂ composites show poor interface of composites compared with the irradiated ones, as observed in SEM micrographs.     

Multipass precedence analysis

Summary This paper defines a hierarchy of languages which is properly contained in the context sensitive languages and which starts with the context free family. The hierarchy is defined inductively by controlling labeled linear grammars with languages in one family to yield languages in the next larger family. The families of the hierarchy have properties analogous to those of the context free family, in particular, the new mechanism introduced is very suitable for parsing.A language in the n-th family is specified by a sequence of n — 1 labeled linear grammars and a context free grammar. By assuming that the reversals of the first n — 1 grammars and the last labeled linear grammar are precedence grammars, the concepts and parsing algorithm of Wirth and Weber extend to yield a parsing algorithm within the hierarchy. This considerably enhances the usefulness of the construction and allows much of the power of the context sensitive languages to become accessible in measured amounts for potential programming applications.     

IR spectroscopic study on the thermal degradation of plastic security cover sheets of some documents

The change in IR spectra of plastic security cover sheets of ethylene vinylacetate copolymer during thermal treatment was investigated. The results obtained revealed that the temperature reduced the concentration of the ester group; moreover, the carbonyl band disappeared at high temperatures from 200 to 220°C, as well as broading of the absorption aliphatic–CH band. The change in the mechanical properties, degree of swelling in water, and refractive index of the samples during thermal treatment were also investigated. © 1993 John Wiley & Sons, Inc.     

A counterexample to an algorithm for computing monotone hulls of simple polygons

A two-stage algorithm was recently proposed by Sklansky (1982) for computing the convex hull of a simple polygon P. The first step is intended to compute a simple polygon $\text{P}{}^1$ which is monotonic in both the x and y directions and which contains the convex hull vertices of P. The second step applies a very simple convex hull algorithm on $\text{P}{}^1$. In this note we show that the first step does not always work correctly and can even yield non-simple polygons, invalidating the use of the second step. It is also shown that the first step can discard convex hull vertices thus invalidating the use of any convex hull algorithm in the second step.     

The Dynamic Lot-Sizing Problem for Multiple Items Under Limited Capacity

This paper addresses the problem of scheduling the timing and quantities of production of n different products over m periods for a single production facility with a prespecified capacity. We assume that the demand is deterministic and can vary from one period to another and from one product to another. The objective is to minimize the sum of production setup and inventory holding costs. For medium-size problems, optimal solution algorithms do not yet exist and therefore heuristic solution algorithms are of interest. Most of the existing heuristics make use of the “forward-pass” concept in one way or the other. Forward pass means we begin by determining the lot sizes for earlier periods before moving to study the later periods. In this paper we study the forward-pass approach as well as a different solution approach which we call the four-step algorithm. We develop the feasibility conditions for pure forward-pass algorithms. Finally, we perform a comparative evaluation study.     

Using Semantics for Policy-Based Web Service Composition

Proliferation of Web technologies and the ubiquitous Internet has resulted in a tremendous increase in the need to deliver one-stop Web services, which are often composed of multiple component services that cross organizational boundaries. It is essential that these Web services, referred to in this paper as service flows, be carefully composed in a dynamic and customized manner to suit to the changing needs of the customers. This composition should be conducted in such a manner that (i) the composed service flow adheres to the policies imposed by the organizations offering the component services, (ii) the selected component services are compatible with one another so that the entire composition would result in a successful service flow, and (iii) the selected component services most closely meet the customer requirements. In this paper, we propose a policy-based Web service composition that utilizes the semantics associated with the component services.We consider policies imposed by different entities while composing service flows, which include service policies (imposed by the organizations offering component services), service flow policies (associated with the entire service flow), and user policies (the user requirements expressed as policies). In addition to these policies, one may consider rules at the syntactic and semantic levels that can be used to select relevant component services in order to compose customized service flows, by considering the notions of syntactic, semantic and policy compatibility. We model the different policies and the service topic ontology using OWL, DAML-S, RuleML and RDF standards.Recommended by: Athman Bouguettaya and Boualem BenatallahThe work is supported by and a grant from the Meadowlands Environmental Research Institute, New Jersey Meadowlands Commission.     

Solid–liquid expression from denaturated plant tissue: Filtration–consolidation behaviour

The objective of this study is to investigate the filtration–consolidation behaviour of biological tissue (sugar beet specimens), denaturated by pulsed electric field (PEF) and freezing–thawing pretreatments. The degree of cell membrane damage was evaluated by the tissue electrical conductivity measurement (determination of the cell disintegration index Z). The PEF-treated and freeze–thawed tissues show different structure response on the applied compressive pressure and different filtration–consolidation behaviour. The value of fracture pressure (P_f ≈ 58.5 bar) is the lowest and the value of tissue deformation under fracture (ε_f ≈ 0.46) is the highest for sugar beet tissue treated by freezing/thawing. PEF treatment leads to more rigid and more fragile tissue structure (P_f ≈ 63.8 bar, ε_f ≈ 0.28) than freeze–thawed tissue. Untreated tissue seems to be stronger and less fragile than the PEF-treated tissue (P_f ≈ 84.1 bar, ε_f ≈ 0.37). Different tissue reactions on the loading pressure evidently reflect the difference between microstructures of treated and untreated tissues. The filtration/consolidation behaviour during liquid expression from a sugar beet tissue also depends on the type and degree of structure denaturation. Tissues treated by PEF and freezing/thawing demonstrate two consolidation stages of expression (primary and secondary). However, the freeze–thawed tissue tends to modify the expression mechanism under the higher loading pressure (60 bar) with approach to the primary consolidation behaviour. The simplified semi-empirical consolidation model permits a reasonably good prediction of expression behaviour from the denaturated sugar beet tissue and estimation of consolidation coefficient b under different pressures. The extrapolation of curves b(P) shows the value of hypothetical pressure, P_max ≈ 90 bar at which the consolidation behaviour would be similar to both PEF-treated and freeze–thawed tissues.     

Equilibrium adsorption isotherm and controlled release of antibiotic drug chloroamphenicol from poly(2‐vinyl pyridine/acrylic acid) hydrogels prepared by gamma radiation

High water sorption of 2‐vinyl pyridine (2‐VP)/acrylic acid (AAc) hydrogel were prepared by free‐radical polymerization in aqueous solution of 2‐VP with AAc as comonomer. The amount of ionic monomer (AAc), the irradiation dose of prepared hydrogel, the pH, and the concentration of drug play an important factor on loading, adsorption, and releasing of water‐soluble chloroamphenicol drug. As a result of dynamic swilling tests, the effect of relative content of AAc on the swelling showed that it allowed a non‐Fickian type of water diffusion. The adsorption of the drug onto (2‐VP/AAc) hydrogels was studied by Freundlish adsorption isotherm. The drug concentrations showed an influence on the adsorption of drug which increased with increasing AAc content. From Freundlish adsorption isotherm, the empirical constants, k and n, can be evaluated and showed the ability of hydrogel to be loaded by the drug and the affinity of the drug to be uptake onto the hydrogel respectively. FTIR, TGA, and SEM techniques were used to study the characterization of hydrogel (2‐VP/AAc). Additionally, the release of the drug loaded from hydrogel discs was studied microbiologically to show that hydrophilic structure of the hydrogel has an antimicrobial effect as a dehydration of cytoplasm and unbalance of the cell wall functions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Performance of olive waste ash concrete exposed to elevated temperatures

This study explores the influence of olive waste ash (OWA) on the performance of concrete exposed to elevated temperatures in the range from 400 to 600 °C. The performance of concrete to elevated temperature was evaluated using compressive strength and electrical charge of concrete. Three OWA levels were used in the study: 7%, 15%, and 22% by weight of cement. The other experimental parameters investigated in the study were elevated temperature (400 and 600 °C), aggregate type (crushed basalt and volcanic tuff), w/c ratio (0.5 and 0.7), and air content (non-air and air entrained). After the initial moist curing period of 90 days, concrete specimens were exposed to elevated temperatures for a period of 2 h using an electric furnace.