A simulation optimisation tool for planning of low-income housing projects

Construction of low-income housing projects is a recurring process and is associated with uncertainties that arise from the unavailability of resources. This paper presents a case study that discusses how computer simulation and optimisation are used to aid government agencies and/or contractors in planning of such projects. It illustrates the optimisation of project objectives, taking into consideration the interaction amongst involved resources. As such, total duration and the associated total costs, including direct and indirect costs, can be estimated and optimised. One Youth Habitation project that is executed in 6th of October City in Egypt is analysed in a step-by-step procedure to demonstrate the capability of proposed computer simulation and optimisation prototype (named LIHouse{_}Sim) in the modelling construction of low-income housing projects using bearing block walls with hollow core technique. The presented tool proves its practicality to contractors in estimating the time and costs of the recurring process of low-income housing construction, considering complex interdependencies between construction resources and the uncertainties associated with construction activities. The LIHouse{_}Sim prototype is used to perform a wide analysis for the alternative of the effective optimisation criteria in the bearing block walls/hollow core technique and for the genetic algorithm optimisation approach elements.     

Micromechanics modeling of viscoelastic properties of hybrid composites with shunted and arbitrarily oriented piezoelectric inclusions

A comprehensive micromechanics model is developed to estimate the effective viscoelastic properties of hybrid composites containing polymer matrix, conductive inclusions and shunted piezoelectric inclusions. The model is derived using the viscoelastic correspondence principle in conjunction with the Mori-Tanaka approach and the orientation averaging scheme. Three dimensional complex moduli are explicitly presented for hybrid composites with any orientation distribution. The model is first validated by comparison with available experimental results. Then, the loss factors are examined for hybrid composites with inclusions of various volume fractions and of shapes ranging from thin disks to long fibers. It is seen that hybrid composites with randomly oriented inclusions exhibit shear loss factors which are not possible with monolithic piezoelectric plate. Furthermore, the numerical results indicate that composites with long spheroid inclusions provide the best damping performance. The results recommend that aligned inclusion composites are good for alleviating longitudinal oscillations. If oscillation energy needs to be dissipated in all directions and for all modes, three dimensional random composites should be used. It is also observed that spherical inclusion composites cannot improve shear damping irrespective of the orientation and the volume fraction. In general, to achieve a pronounced damping piezoelectric inclusions that lie in aspect ratio range 0.1?α?2 should be avoided.     

Decline of natural killer cell target binding and lytic activity in mice exposed to rotation stress.

Examined the effect of rotation-induced stress on (1) the percentage distribution of natural killer (NK) YAC-1 target-binding cells and (2) NK cell activity from splenic lymphocytes of C3H/HeJ mice. Following a 6-day stress regimen, a marked decline in both the percentage of target-binding cells and in NK cell activity was observed. This decline was first evident 13 days after initiation of stress and persisted for 2 wks. Data indicate that intermittent rotation stress over a 6-day period results in a delayed but persistent deleterious effect on NK-YAC-1 target binding and NK cell activity that may be involved in cancer progression of the host. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast and accurate analytic formulas for calculating the parametersof a general broadside-coupled coplanar waveguide for (M)MICapplications

Fast and accurate analytic formulas for calculating the quasistatic transverse electromagnetic (TEM) parameters of a general broadside-coupled coplanar waveguide (GBSC CPW) are presented. Simplicity, high speed of computation, and accuracy suggest the use of these formulas for (M)MIC CAD (monolithic) microwave integrated circuit computer-aided design programs. Numerical calculations are presented to investigate various electrical properties of the structure. An asymmetrical BSC CPW and the single CPW resulting from connecting the two coupled strips of the GBSC CPW at the input and the output ports are analyzed. Criteria are obtained to ensure the coplanar behavior of the structure     

A multi-criterion decision-making model for contractor prequalification selection

The factors used in this model are financial stability, experience, references, past performance, current work load, staff availability, manpower resources, company organization, office location, experience in geographic location of project, quality performance, failure to complete contracts, procurement experience, safety consciousness and claim attitude.     

Persistence of some phenylamide pesticides in the aquatic environment—II. Adsorption on clay minerals

Adsorption of IPC, CIPC, Linuron, Neburon and Vitavax on bentonite clays (H-, Fe- and Ca-forms) was investigated. Adsorption was found to conform with Freundlich's equation and to depend on the nature of saturating cation as well as the chemical structure of phenylamides. Considerable amounts of bentonite are needed to bring about effective removal of these pesticides from polluted water. The role of suspended clay minerals in the decontamination of surface waters will be rather limited.     

Electrical properties of manganese doped Ga1−xInxAs grown by liquid phase epitaxy

Mn-doped Ga_1?xIn_xAs crystals (0 < x < 0.25) have been grown by the LPE technique, and the doping characteristics and electrical properties of the layers have been studied by Hall measurement. The distribution coefficient of Mn has been found to depend on the substrate orientation. The acceptor enerby level is about 77 meV and is comparable to that of Mn-doped GaAs. p-n junction diodes with high InAs compositions, grown using the step grading technique, showed a diode factor of 2. Electron diffusion lengths greater than 3μm have been measured in these Mn doped layers.     

Persistence of some phenylamide pesticides in the aquatic environment—III. Biological degradation

Mixed population of microorganisms of river water and sewage did not metabolize IPC, CIPC, Linuron, Monuron, Stam and Vitavax during the tested period lasting for 4 months. Bacillus cereus, when added to the aqueous solutions of these pesticides, was capable to degrade IPC, Linuron, Stam and Vitavax whereas CIPC and Monuron were chemically stable. The investigated phenylamides have no inhibitory effects on bacteria and are not expected to affect the process of self-purification of surface waters. Susceptibility of phenylamides to biodegradation in aquatic environment and their health hazards were discussed.     

THE EFFECT OF CONCRETE BOND ON THE STRESS INTENSITY FACTORS FOR AN EDGE CRACK IN A REINFORCING BAR

Abstract— The stress intensity factors at the tip of an edge crack in a round bar embedded in the tension zone of a concrete beam are found for several conditions of bond failure between the steel reinforcing bar and the concrete. A two-dimensional finite element technique is modified to represent the third dimension, the steel-concrete interface and debonding. The integrated form of the Paris crack growth law is used with the calculated stress intensity factors to compute the propagating fatigue lives for embedded bar and bar in air. The results indicate that embedded bars appear to have shorter fatigue propagation lives than bars in air if the crack initiators are less than 0.05 of the bar diameter, while for deeper crack initiators, the opposite is true. It has also been shown that the propagating fatigue life of the bar increases with the degree of bond.     

Fabrication of porous polymer monoliths in polymeric microfluidic chips as an electrospray emitter for direct coupling to mass spectrometry

Coupling of polymeric microfluidic devices to mass spectrometry is reported using porous polymer monoliths (PPM) as nanoelectrospray emitters. Lauryl acrylate-co-ethylene dimethacrylate porous polymer monolith was photopatterned for 5 mm at the end of the channel of microfluidic devices fabricated from three different polymeric substrate materials, including the following: poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), and cyclic olefin copolymer (COC). Spraying directly from the end of the chip removes any dead volume associated with inserted emitters or transfer lines, and the presence of multiple pathways in the PPM prevents the clogging of the channels, which is a common problem in conventional nanospray emitters. Spraying from a microfluidic channel having a PPM emitter produced a substantial increase in TIC stability and increased sensitivity by as much as 70x compared to spraying from an open end chip with no PPM. The performance of PPM emitter in COC, PMMA, and PDMS chips was compared in terms of stability and reproducibility of the electrospray. COC chips showed the highest reproducibility in terms of chip-to-chip performance, which can be attributed to the ease and reproducibility of the PPM formation due to the favorable optical and chemical properties of COC. We have further tested the performance of the COC chips by constant infusion of poly(propylene glycol) solution at organic content ranging from 10 to 90% methanol and at flow rates ranging from 50 to 1000 nL/min, showing optimum spraying conditions (RSD < 5%) at 50-70% organic content and at flow rates from 100 to 500 nL/min. The PPM sprayer was also used for protein preconcentration and desalting prior to mass spectrometric detection, and results were comparable with a chip spraying from an electrospray tip.