Vehicle routing problem with uncertain demands: An advanced particle swarm algorithm

The Vehicle Routing Problem (VRP) has been thoroughly studied in the last decades. However, the main focus has been on the deterministic version where customer demands are fixed and known in advance. Uncertainty in demand has not received enough consideration. When demands are uncertain, several problems arise in the VRP. For example, there might be unmet customers’ demands, which eventually lead to profit loss. A reliable plan and set of routes, after solving the VRP, can significantly reduce the unmet demand costs, helping in obtaining customer satisfaction. This paper investigates a variant of an uncertain VRP in which the customers’ demands are supposed to be uncertain with unknown distributions. An advanced Particle Swarm Optimization (PSO) algorithm has been proposed to solve such a VRP. A novel decoding scheme has also been developed to increase the PSO efficiency. Comprehensive computational experiments, along with comparisons with other existing algorithms, have been provided to validate the proposed algorithms.     

Determination of the Optimum Conditions for Leaching of Zinc Cathode Melting Furnace Slag in Ammonium Chloride Media

This research is part of a continuing effort to leach zinc from zinc cathode melting furnace slags (ZCMFSs) to produce zinc oxide. The slag with an assay of 68.05 pct Zn was used in ammonium chloride leaching for zinc extraction. In this paper, the effects of influential factors on extraction efficiency of Zn from a ZCMFS were investigated. The Taguchi’s method based on orthogonal array (OA) design has been used to arrange the experimental runs in order to maximize zinc extraction from a slag. The softwares named Excel and Design-Expert 7 have been used to design experiments and subsequent analysis. OA L ₂₅ (5⁵) consisting of five parameters, each with five levels, was employed to evaluate the effects of reaction time (t = 10, 30, 50, 70, 90 minutes), reaction temperature [T = 313, 323, 333, 343, 353 (40, 50, 60, 70, 80) K (°C)], pulp density (S/L = 20, 40, 60, 80, 100 g/L), stirring speed (R = 300, 400, 500, 600, 700 rpm), and ammonium chloride concentration (C = 10, 15, 20, 25, 30 pctwt), on zinc extraction percent. Statistical analysis, ANOVA, was also employed to determine the relationship between experimental conditions and yield levels. The results showed that the significant parameters affecting leaching of slag were ammonium chloride concentration and pulp density, and increasing pulp density reduced leaching efficiency of zinc. However, increasing ammonium chloride concentration promoted the extraction of zinc. The optimum conditions for this study were found to be t ₄: 70 minutes, T ₅: 353 K (80 °C), (S/L)₂: 40 g/L, R ₃: 500 rpm, and C ₄: 25 pctwt. Under these conditions, the dissolution percentage of Zn in ammonium chloride media was 94.61 pct.     

Synthesis,characterization and magnetic properties of polythiophene/SrFe12-x(ZrZn)0.5xO19 nanocomposite as a microwave absorber

Ferrites are an important group of magnetic materials which are used as absorbers. The incorporation of ferrite and conducting polymer achieves great enhancement in microwave absorption properties. The nanocomposites of hexagonal ferrites embedded by conducting polymers such as polypyrrole, polyaniline and polythiophene (PTH) have been paid much attention. In the present study, strontium hexagonal ferrite doped by Zr and Zn with the final formula of SrFe_12-x(ZrZn)_0.5xO19 considering x = 0.9 and embedded by PTH was produced to achieve a nanocomposite with the highest microwave absorbing ability. In this study, after synthesis of SrFe₁₂O₁₉(ZrZn)_0.5xO19 and PTH, the nanocomposite was prepared by in situ polymerization. Wrapping the ferrite particles and PTH chains could form nanocomposite properly, and therefore acceptable interactions were observable between SrFe_12-x(ZrZn)_0.5xO19ferrite particles and PTH polymer chains in the composites. Assessing the X-ray diffraction (XRD) patterns of SrFe_12-x(ZrZn)_0.5xO19, PTH, and PTH/SrFe_12-x(ZrZn)_0.5xO19 nanocomposite indicated that the PTH characteristic peak shifts slightly and its peak intensity reduces, which may be attribute to the coating of PTH polymer chains onto SrFe_12-x(ZrZn)_0.5xO19 particles. We revealed also lower magnetic properties in the obtained nanocomposite. The morphological assessment also suggested that PTH could effectively coat the SrFe_12-x(ZrZn)_0.5xO19 particles. The synergistic effect of SrFe_12-x(ZrZn)_0.5xO19 particle plus PTH leads to microwave absorption percentage higher than 95% by PTH/SrFe_12-x(ZrZn)_0.5xO19 nanocomposite. Overall, nanocomposite creating by coupling interaction between SrFe_12-x(ZrZn)_0.5xO19 particles (x = 0.9) and PTH can effectively lead to achieve the highest rate of absorption of electromagnetic waves.     

Chemical composition,antibacterial and antifungal activities of seed essential oil of Ferulago angulata

The aim of this study was to determine the chemical composition and the in vitro antimicrobial effects of seed essential oil of Ferulago angulata. The oil analyses by GC and GC/MS resulted in the identification of 39 compounds representing 91.07% of the oil. The major constituents were (Z)-β-ocimene (19.93%), α-pinene (15.50%), p-cymene (7.67%), sabinene (7.49%), β-phellandrene (5.5%), and α-phellandrene (4.95%). The oil was also screened for its antimicrobial properties against six bacteria (Erwinia amylovora, Xanthomonas oryzae, Pseudomonas syringae, Pectobacterium carotovorum, Ralstonia solanacearum, Bacillus thuringiensis) and six fungi (Alternaria alternata, Culvularia fallax, Macrophomina phaseolina, Fusarium oxysporum, Cytospora sacchari, Colletotrichum tricbellum). According to the results of antibacterial activity, B. thuringiensis (with 8 µL mL^?1 minimal inhibitory concentration (MIC) and 15 µL mL^?1 minimum bactericidal concentration (MBC)) was the most sensitive bacterium; P. carotovorum and R. solanacearum (with 20 µL mL^?1 MIC and 30< MBC) were the most resistant bacteria. Additionally, a broad differentiation against all of the tested fungi showed that the most susceptible and resistant fungi after 6 days at the highest concentration (800 µL L^?1) were F. oxysporum (100.0 ± 0.00%) and C. tricbellum (52.50 ± 1.67%) of growth inhibition, respectively.     

Preparation of the γ-Al2O3/PANI nanocomposite via enzymatic polymerization

Peroxidase-catalyzed template-guided polymerization of aniline in the presence of γ- alumina nanosheet (NS) particles have been carried out in aqueous media and γ-Al₂O₃/PANI nanocomposite was obtained. The polymerization of aniline occurred in aqueous solution in the presence of SPS (sulfonated polystyrene) as a template and SDS (sodium dodecyl sulfate) as a surfactant. Both obtained nanocomposites were comparable by SEM images. It was demonstrated that the γ-Al₂O₃ NS/PANI-SPS nanocomposite has higher conductivity and the γ-Al₂O₃ NS/PANI-SDS nanocomposite has higher void areas. The higher conductivity of γ-Al₂O₃ NS/PANI-SPS nanocomposite is attributed to the higher coated areas of γ-Al₂O₃ NS during polymerization in comparison with γ-Al₂O₃ NS/PANI-SDS which are not coated efficiently as the former. The FT-IR studies showed that the γ-Al₂O₃ NS/PANI nanocomposite was formed by interaction of the polyaniline (PANI) and γ-Al₂O₃ NS. FTIR also showed that the amount of PANI in γ-Al₂O₃ NS/PANI-SPS is more than in γ-Al₂O₃ NS/PANI-SDS. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Modeling and prioritizing demand response programs in power markets

One of the responsibilities of power market regulator is setting rules for selecting and prioritizing demand response (DR) programs. There are many different alternatives of DR programs for improving load profile characteristics and achieving customers’ satisfaction. Regulator should find the optimal solution which reflects the perspectives of each DR stakeholder. Multi Attribute Decision Making (MADM) is a proper method for handling such optimization problems. In this paper, an extended responsive load economic model is developed. The model is based on price elasticity and customer benefit function. Prioritizing of DR programs can be realized by means of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. Considerations of ISO/utility/customer regarding the weighting of attributes are encountered by entropy method. An Analytical Hierarchy Process (AHP) is used for selecting the most effective DR program. Numerical studies are conducted on the load curve of the Iranian power grid in 2007.     

Multi-objective operation management of a renewable MG (micro-grid) with back-up micro-turbine/fuel cell/battery hybrid power source

As a result of today’s rapid socioeconomic growth and environmental concerns, higher service reliability, better power quality, increased energy efficiency and energy independency, exploring alternative energy resources, especially the renewable ones, has become the fields of interest for many modern societies. In this regard, MG (Micro-Grid) which is comprised of various alternative energy sources can serve as a basic tool to reach the desired objectives while distributing electricity more effectively, economically and securely. In this paper an expert multi-objective AMPSO (Adaptive Modified Particle Swarm Optimization algorithm) is presented for optimal operation of a typical MG with RESs (renewable energy sources) accompanied by a back-up Micro-Turbine/Fuel Cell/Battery hybrid power source to level the power mismatch or to store the surplus of energy when it’s needed. The problem is formulated as a nonlinear constraint multi-objective optimization problem to minimize the total operating cost and the net emission simultaneously. To improve the optimization process, a hybrid PSO algorithm based on a CLS (Chaotic Local Search) mechanism and a FSA (Fuzzy Self Adaptive) structure is utilized. The proposed algorithm is tested on a typical MG and its superior performance is compared to those from other evolutionary algorithms such as GA (Genetic Algorithm) and PSO (Particle Swarm Optimization).     

Axial compressive behavior of concrete actively confined by metal strips; part A: experimental study

This paper presents the results of an experimental study on the application of strapping technique for retrofit of concrete compressive specimens. In this technique, standard strapping devices, which are used in the packaging industry, are applied to post-tension high strength metal strips around the concrete columns. Experimental program included axial compressive tests on 72 cylindrical and prismatic compressive specimens, which were actively confined by pre-stressed metal strips. The effects of various parameters on strength and ductility of confined concrete were studied including compressive strength of concrete, mechanical volumetric ratio of confining strips, post-tensioning force in the strip, number of strip layers wrapped around the specimens and details of strip joint. The effects of strength and ductility of confining strips on the behavior of confined specimens were also studied. Longitudinal and lateral strains of concrete and strain of the strips were monitored. Test results showed significant increase in the strength and ductility of specimens due to active confinement by metal strips. It was observed that ductility of confining material plays the most important role in enhancement of concrete ductility. The gain in strength is strongly dependent to the effective mechanical volumetric ratio of confining strips. It was also observed that the active confinement of concrete by post-tensioning the confining element results in stiffer pre-peak response of concrete specimens than the usual passive confinement.     

Adolescents exhibit behavioral differences from adults during instrumental learning and extinction.

Adolescence is associated with the development of brain regions linked to cognition and emotion. Such changes are thought to contribute to the behavioral and neuropsychiatric vulnerabilities of this period. We compared adolescent (Postnatal Days 28–42) and adult (Postnatal Day 60+) rats as they performed a simple instrumental task and extinction. Rats were trained to poke into a hole for a food-pellet reinforcer. After six days of training, rats underwent extinction sessions in which the previously rewarded behavior was no longer reinforced. During extinction, we examined the effects of continued presentation of a cue light and food restriction. Adults and adolescents exhibited similar performance during training, although adolescents made more task-irrelevant pokes, consistent with increased exploration. Adults made more premature pokes, which could indicate a more exclusive focus on the task. During extinction, adolescents made more perseverative (previously reinforced) pokes than adults. This behavior was strongly modulated by the combination of motivational factors present (food restriction and cue light), indicating that adolescents were differentially sensitive to them. Furthermore, food restriction induced greater open-field activity in adolescents but not in adults. Thus, as the neural circuitry of motivated behavior develops substantially during adolescence, so too does the behavioral sensitivity to motivational factors. Understanding how such factors differently affect adolescents may shed light on mechanisms that lead to the development of disorders that are manifested during this period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Demand response modeling considering Interruptible/Curtailable loads and capacity market programs

Recently, a massive focus has been made on demand response (DR) programs, aimed to electricity price reduction, transmission lines congestion resolving, security enhancement and improvement of market liquidity. Basically, demand response programs are divided into two main categories namely, incentive-based programs and time-based programs. The focus of this paper is on Interruptible/Curtailable service (I/C) and capacity market programs (CAP), which are incentive-based demand response programs including penalties for customers in case of no responding to load reduction. First, by using the concept of price elasticity of demand and customer benefit function, economic model of above mentioned programs is developed. The proposed model helps the independent system operator (ISO) to identify and employ relevant DR program which both improves the characteristics of the load curve and also be welcome by customers. To evaluate the performance of the model, simulation study has been conducted using the load curve of the peak day of the Iranian power system grid in 2007. In the numerical study section, the impact of these programs on load shape and load level, and benefit of customers as well as reduction of energy consumption are shown. In addition, by using strategy success indices the results of simulation studies for different scenarios are analyzed and investigated for determination of the scenarios priority.