A hybrid discrete particle swarm optimization for vehicle routing problem with simultaneous pickup and delivery

Vehicle routing problem (VRP) is an important and well-known combinatorial optimization problem encountered in many transport logistics and distribution systems. The VRP has several variants depending on tasks performed and on some restrictions, such as time windows, multiple vehicles, backhauls, simultaneous delivery and pick-up, etc. In this paper, we consider vehicle routing problem with simultaneous pickup and delivery (VRPSPD). The VRPSPD deals with optimally integrating goods distribution and collection when there are no precedence restrictions on the order in which the operations must be performed. Since the VRPSPD is an NP-hard problem, we present a heuristic solution approach based on particle swarm optimization (PSO) in which a local search is performed by variable neighborhood descent algorithm (VND). Moreover, it implements an annealing-like strategy to preserve the swarm diversity. The effectiveness of the proposed PSO is investigated by an experiment conducted on benchmark problem instances available in the literature. The computational results indicate that the proposed algorithm competes with the heuristic approaches in the literature and improves several best known solutions.     

Symmetric positive solutions of fourth order integral BVP for an increasing homeomorphism and homomorphism with sign-changing nonlinearity on time scales

In this paper, we consider the eigenvalue problems for fourth order integral boundary value problems on time scales for an increasing homeomorphism and homomorphism with sign changing nonlinearities. By using a fixed point index theorem, we give the existence of eigenvalue intervals in which there exist one symmetric positive solution to the problem. An example is also given to demonstrate the main results.     

Evaluation of ISSR markers for genetic diversity analysis in Anatolian water buffaloes

BACKGROUND: The utilisation of molecular markers has increased in molecular research recently. Inter‐simple sequence repeat (ISSR) markers allow the analysis of genomes without preliminary sequence information, since random primers are used. The purpose of the present study was to evaluate ISSR markers for assessing the genetic diversity of indigenous Anatolian Water Buffaloes reared in Afyon, Konya and Sivas provinces of Turkey, with a view to conservation of the gene resources. RESULTS: The 11 ISSR primers chosen for the analysis revealed a total of 110 bands, of which 76 (69.09%) were polymorphic. Also, genetic similarity, polymorphic information content (PIC), resolving power (R_p) and mean resolving power (R_p ), heterozygosity (H) and Shannon index (I) were calculated as 0.9479–0.9562, 0.35 ± 0.20, 2.73, 0.27, 0.18 ± 0.07 and 0.28 ± 0.11, respectively. CONCLUSION: The ISSR markers were found to be promising for assessing the genetic diversity in buffalo populations. Potential genetic parameters such as PIC, R_p, R_p , H and I were effectively used in this study. Copyright © 2011 Society of Chemical Industry     

Relaxation phenomena and structural modifications of substituted polythiophenes during the p-doping processes. An electrochemical and morphological study

Electrodes modified by polythiophenes bearing different substituents have been prepared and the behaviour of the conducting polymers has been studied with respect to the structural phenomena occurring in the correspondence to the doping and the relevant undoping processes. The effects of experimental parameters, such as undoping potential and time, have been investigated. The steric hindrance of the substituents on the polymer chain is demonstrated to play a fundamental role in determining the extent of compactness of the film, as induced by polarisation of the electrode at potentials at which the previously charged polymer is neutralised. Such a conclusion is in accordance with prediction of the electrochemical stimulated conformational relaxation model. Electrochemical AFM measurements have been performed in order to acquire a direct view of the morphological modifications of the polymer coatings during the reduction.     

Fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds and common fire retardants

In this study, the fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds (didecyl dimethyl ammonium chloride (DDAC) and didecyl dimethyl ammonium tetrafluoroborate (DBF)) were compared with the performance of untreated control specimens and specimens treated with common fire retardants ((monoammonium phosphate (MAP), diammonium phosphate (DAP) and ammonium sulphate (AS)). Test specimens were treated with 1% and 4% (% m/v) aqueous solutions of the chemicals. The fire performance tests were the fire tube test (ASTM E 69) which measures mass losses in the specimens and the cone calorimeter test (ASTM E 1354) which measures mass loss, heat release rate, time for sustained ignition, effective heat of combustion, and specific extinction area. The results from the cone calorimeter tests were used to estimate the flame spread index (FSI) in the Steiner tunnel test (ASTM E 84). Heat release rates of the specimens treated with MAP, DAP, and AS were lower than those of both DDAC and DBF-treated specimens and the untreated control specimens. Compared with the untreated specimens, higher heat release rates were observed for the specimens treated with the quaternary ammonia compounds, DDAC and DBF. The estimates for the FSI for DDAC and DBF were for values equal to or higher than for the untreated control specimens. At higher concentration levels, MAP, DAP and AS were effective in decreasing initial contribution of heat release to potential fire. Decay resistance tests were done according to AWPA E 10 standard method using one brown-rot fungus and one white rot-fungus. Decay resistance tests revealed that solid wood specimens treated with DDAC and DBF showed resistance against the fungi tested, however, MAP, DAP and AS did not provide complete protection. While DBF and DDAC increased resistance of plywood specimens, high mass losses in plywood specimens treated with MAP, DAP and AS were obtained.     

Spatial assessment of site suitability for solar desalination plants: a case study of the coastal regions of Turkey

Clean Technologies and Environmental Policy - Many countries, especially in arid and semiarid regions, suffer from water scarcity because of the decline in the existing freshwater reserves by...     

Four‐band electromagnetic energy harvesting with a dual‐layer metamaterial structure

A four‐band metamaterial harvester for harvesting 0.9 GHz, 1.8 GHz, 2.6 GHz, and 5.8 GHz signals is proposed by a dual‐layer structure. 0.9 GHz and 1.8 GHz bands are harvested by the resistors in front layer, whereas harvesting of 2.6 GHz is achieved by the resistors in second layer. All resistors in front and back layer contribute to harvesting at 5.8 GHz. Numerical calculations are verified by two different full‐wave electromagnetic solvers based on finite‐integration and finite‐element techniques. Power dissipation ratios at 0.9 GHz, 1.8 GHz, 2.6 GHz and 5.8 GHz frequencies concentrated at the resistors are found as 82.3%, 82.8%, 74.6%, and 83.6%, respectively, by the finite‐integration‐based solver. Besides, the finite‐element method‐based solver results in harvesting efficiencies of 79.6%, 93.4%, 73.7%, and 93.8%. The efficiency of the harvester is investigated for different oblique incidences. The proposed metamaterial harvester can be a good candidate for multi‐band absorption and harvesting applications.     

An Effective Approach for High‐Efficiency Photoelectrochemical Solar Cells by Using Bifunctional DNA Molecules Modified Photoanode

This paper firstly reports the effect of deoxyribonucleic acid (DNA) molecules extracted from chickpea and wheat plants on the injection/recombination of photogenerated electrons and sensitizing ability of dye‐sensitized solar cells (DSSCs). These high‐yield DNA molecules are applied as both linker bridging unit as well as thin tunneling barrier (TTB) at titanium dioxide (TiO₂ )/dye interface, to build up high‐efficient DSSCs. With its favorable energy levels, effective linker bridging role, and double helix structure, bifunctional DNA modifier shows an efficient electron injection, suppressed charge recombination, longer electron lifetime, and higher light harvesting efficiency, which leads to higher photovoltaic performance. In particular, a photoconversion efficiency (PCE) of 9.23% is achieved by the binary chickpea and wheat DNA‐modified TiO₂ (CW@TiO₂) photoanode. Furthermore, time‐resolved fluorescence spectroscopy measurements confirm a better electron transfer kinetics for DNA‐modified TiO₂ photoanodes, implying a higher electron transfer rate (k_ET). This work highlights a great contribution for the photoanodes that are linked with DNA molecule, which act as both bridging unit and TTB to control the charge recombination and injection dynamics, and hence, boost the photovoltaic performance in the DSSCs.