Genetic algorithm optimization in building portfolio management

A significant proportion of building investment expenditure goes to replacement expenditure for organizations owning a large building stock or portfolio. Over the years, researchers have attempted to develop asset replacement models to aid decision-making in building portfolio management, based upon' a statistical or an heuristic approach. This study attempts to use genetic algorithms to develop models for forecasting long term asset replacement strategies, aiming at smoothing fluctuations of expenditure and resource requirements, and most importantly minimizing the total maintenance and replacement costs. Scenarios are presented to demonstrate how these can be achieved. Further refinement for practical application of the models is also presented.     

Tow impregnation during resin transfer molding of bi-directional nonwoven fabrics

A model has been developed for analyzing resin impregnation of fiber tows during resin transfer molding of bi-directional nonwoven fiber performs. The model is based on the existence of two main regions of resin flow: the macropore space formed among fiber tows and the micropore space formed among individual fiber filaments within a tow. The large difference in permeability between these two regions of flow leads to the potential for void formation during resin transfer molding. The model was formulated for both constant flow rate and constant pressure mold filling. For ambient pressure mold filling, the model predicts a difference in the size of the voids and distribution between axial tows (oriented along the flow direction) and transverse tows (oriented in the transverse direction). When vacuum is imposed on the mold, the model predicts the same resin impregnation behavior for both axial and transverse tows. Furthermore, given sufficient time, voids generated under vacuum mold filling will eventually collapse because of the absence of an opposing internal void pressure. In addition to insights on void formation, the model also provides a basis for the study of the relationship between resin transfer molding parameters and the resin impregnation process.     

Diazoverbindungen. 72. (Diazoalkyl)phosphane – Synthese durch elektrophile Diazoalkansubstitution und oxidative Additionsreaktionen am Phosphor

Diazo Compounds. 72. Diazoalkylphosphanes – Synthesis by Electrophilic Diazoalkane Substitution and Oxidative Addition Reactions at Phosphorus Electrophilic diazoalkane substitution of the diazomethyl compounds 1a,b with the chloro phosphanes 2a-o in the presence of lithium diethylamide yields the diazoalkyl phosphanes 3a-z . Oxidative addition of oxygen, sulfur and selenium at phosphorus leads into the series of oxo, thioxo and selenoxo phosphanes having diazoalkyl substituents ( 4a-d, 5a-m and 7a-d ). The silyl group of 5n,o is cleaved by chromatography on aluminium oxide to yield the (diazomethyl)phosphane sulfides 6a,b .     

Reactions of TATB-Based Explosive with Molten Metal

The reactions of combustion products (CO, H₂O) from the insensitive high explosive LX-17 (92.5 wt% 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), 7.5 wt% Kel-F 800 binder) with molten metal (75 a%Nd, 25 a% Fe) were studied, to determine their contribution to the energy release rate of deflagrating LX-17, Kinetic data taken with gas mixtures of CO and H₂O, and larger-scale tests with LX-17, showed that the reactions were slow and incomplete and that there was no significant contribution to the energy release rate. From the tests with JX-17, the effective flame temperature and burn velocity were dependent on confinement of gas products. LX-17 preheated to 500 K - 510 K showed effective flame temperatures of 1100 K - 1400 K and burn rates of 0.08–0.11 mm/s, depending on the extent of gas confinement by the molten metal.     

Elastic modulus of in-situ composites of a liquid crystalline polymer and polycarbonate

In this paper, we model the elastic modulus of in-situ composite fibers from polymer blends where a fibrous liquid crystalline polymer (LCP) phase is induced by drawing. We propose a composite model to account for the change of the elastic moduli of the reinforcing LCP phase with the draw ratio of the composite fibers. We envisage the LCP phase as a composite of a perfectly oriented chain aggregate and a randomly oriented chain aggregate which are connected in series. We then derive equations for the longitudinal and the transverse elastic moduli of the composite fibers based on the well-known Halpin-Tsai equation and the composite model of the reinforcing LCP phase. Using this approach, we are able to make a number of predictions including the transverse elastic modulus and mechanical anisotropy. Our results show that theoretical predictions of the longitudinal elastic modulus agree fairly well with experimental results for polycarbonate/Vectra composites. The proposed modulus equations will be useful in providing guidelines for fabrication and applications of this new class of polymeric materials.     

Phytic acid and Fe and Zn concentration in lentil (Lens culinaris L.) seeds is influenced by temperature during seed filling period

Phytic acid (PA), found in cereal and legume staple foods, is considered an antinutrient for iron (Fe) and zinc (Zn). Amongst numerous factors, temperature has a substantial effect on PA synthesis in seeds of legumes. PA, Fe, and Zn concentrations were determined for mature seeds of eleven lentil genotypes grown under simulated long term temperature regimes representative of Saskatoon, Canada (decreasing temperatures) and Lucknow, India (increasing temperatures). PA and Zn concentrations in lentil seeds were significantly higher in the rising temperature regime (8.8 mg/g and 69 mg/kg, respectively) than in the decreasing temperature regime (6.7 mg/g and 61 mg/kg, respectively). Fe concentrations followed the same trend (116 vs. 113 mg/kg). The cooler temperatures of temperate summers might be an important factor in the production of seeds with lower PA concentrations. These results are relevant to the development of biofortification strategies aimed at lowering the PA content in staple crops.     

Application of bacteria involved in the biological sulfur cycle for paper mill effluent purification

In anaerobic wastewater treatment, the occurrence of biological sulfate reduction results in the formation of unwanted hydrogen sulfide, which is odorous, corrosive and toxic. In this paper, the role and application of bacteria in anaerobic and aerobic sulfur transformations are described and exemplified for the treatment of a paper mill wastewater. The sulfate containing wastewater first passes an anaerobic UASB reactor for bulk COD removal which is accompanied by the formation of biogas and hydrogen sulfide. In an aeration pond, the residual COD_organic and the formed dissolved hydrogen sulfide are removed. The biogas, consisting of CH₄ (80-90 vol.%), CO₂ (10-20 vol.%) and H₂S (0.8-1.2 vol.%), is desulfurised prior to its combustion in a power generator thereby using a new biological process for H₂S removal. This process will be described in more detail in this paper. Biomass from the anaerobic bioreactor has a compact granular structure and contains a diverse microbial community. Therefore, other anaerobic bioreactors throughout the world are inoculated with biomass from this UASB reactor. The sludge was also successfully used in investigation on sulfate reduction with carbon monoxide as the electron donor and the conversion of methanethiol. This shows the biotechnological potential of this complex reactor biomass.