Iterated beam search for the combined car sequencing and level scheduling problem

The level scheduling problem is concerned with the final stage of a multi-stage just-in-time production system so that different models of a product are evenly distributed in a discrete production sequence, thereby making the problem practically an unconstrained optimisation problem. The car sequencing problem, on the other hand, is a constraint satisfaction problem based on a number of options constricting the final assembly schedule. The combined car sequencing and level scheduling problem aims to find the optimal production schedule that evenly distributes different models over the planning horizon and satisfies all option constraints. This paper proposes a parametric iterated beam search algorithm for the combined problem that can be used either as a heuristic or as an exact optimisation method. The paper includes a computational study based on a 54-instance test bed that proves the effectiveness of the proposed algorithm.     

Advanced Power Conversion Efficiency in Inventive Plasma for Hybrid Toroidal Reactor

Apex hybrid reactor has a good potential to utilize uranium and thorium fuels in the future. This toroidal reactor is a type of system that facilitates the occurrence of the nuclear fusion and fission events together. The most important feature of hybrid reactor is that the first wall surrounding the plasma is liquid. The advantages of utilizing a liquid wall are high power density capacity good power transformation productivity, the magnitude of the reactor’s operational duration, low failure percentage, short maintenance time and the inclusion of the system’s simple technology and material. The analysis has been made using the MCNP Monte Carlo code and ENDF/B–V–VI nuclear data. Around the fusion chamber, molten salts Flibe (LI₂BeF₄), lead–lithium (PbLi), Li–Sn, thin-lityum (Li₂₀Sn₈₀) have used as cooling materials. APEX reactor has modeled in the torus form by adding nuclear materials of low significance in the specified percentages between 0 and 12 % to the molten salts. In this study, the neutronic performance of the APEX fusion reactor using various molten salts has been investigated. The nuclear parameters of Apex reactor has been searched for Flibe (LI₂BeF₄) and Li–Sn, for blanket layers. In case of usage of the Flibe (LI₂BeF₄), PbLi, and thin-lityum (Li₂₀Sn₈₀) salt solutions at APEX toroidal reactors, fissile material production per source neutron, tritium production speed, total fission rate, energy reproduction factor has been calculated, the results obtained for both salt solutions are compared.     

Scheduling in a two-machine flow-shop for earliness/tardiness under learning effect

In the literature, earliness/tardiness (E/T) problem was known as weighted absolute deviation problem, and both tardiness and earliness is very important performance criteria for scheduling problem. While total tardiness criteria provides adaptation for due date (ignoring results of earliness done jobs), it deals with only cost of tardiness. However this phenomenon has been started to change with just-in-time (JIT) production concept. On JIT production, earliness is as important as tardiness. The phenomenon of the learning effect has been extensively studied in many different areas of operational research. However, there have been a few studies in the general context of production scheduling such as flow-shop scheduling. This paper addresses the minimization of the total earliness/tardiness penalties under learning effects in a two-machine flow-shop scheduling problem. Jobs have a common due date. We present mathematical model to obtain an optimal schedule for a given job sequence. We also present heuristics that use genetic algorithm and tabu search, based on proposed properties. Furthermore, random search was used for showing the significance of the study by comparison purpose. A new set of benchmark problems is presented with the purpose of evaluating the heuristics. The experimental results show that the performance of proposed approach is quite well, especially for the instances of large size.     

A recombination-based hybridization of particle swarm optimization and artificial bee colony algorithm for continuous optimization problems

This paper presents a hybridization of particle swarm optimization (PSO) and artificial bee colony (ABC) approaches, based on recombination procedure. The PSO and ABC are population-based iterative methods. While the PSO directly uses the global best solution of the population to determine new positions for the particles at the each iteration, agents (employed, onlooker and scout bees) of the ABC do not directly use this information but the global best solution in the ABC is stored at the each iteration. The global best solutions obtained by the PSO and ABC are used for recombination, and the solution obtained from this recombination is given to the populations of the PSO and ABC as the global best and neighbor food source for onlooker bees, respectively. Information flow between particle swarm and bee colony helps increase global and local search abilities of the hybrid approach which is referred to as Hybrid approach based on Particle swarm optimization and Artificial bee colony algorithm, HPA for short. In order to test the performance of the HPA algorithm, this study utilizes twelve basic numerical benchmark functions in addition to CEC2005 composite functions and an energy demand estimation problem. The experimental results obtained by the HPA are compared with those of the PSO and ABC. The performance of the HPA is also compared with that of other hybrid methods based on the PSO and ABC. The experimental results show that the HPA algorithm is an alternative and competitive optimizer for continuous optimization problems.     

Determining the capacity and its level of utilization in make-to-order manufacturing: A simple deterministic model for single-machine multiple-product case

A simple deterministic model is developed to determine the capacity and its level of utilization for a single specific machine producing multiple products in make-to-order manufacturing plants. It integrates the variables of processing time, set-up time, product defective rate, and maintenance downtime. The number of product types and the number of lots per product are critical determinants. The model first computes the net production quantities per unit of time for each product type and for the product mixtures, and then, capacity utilization figures are derived based on the net capacity inverse coefficients and net product quantities per planned time unit for each product type and product mixture.     

Electrical and Photoresponse Properties of Al/p-Si/Y 1-x Sr x MnO 3 /Al Heterojunction Photodiodes

The electrical and photoresponse properties of Al/p-Si/Y1-xSrxMnO3/Al diodes were investigated by using current-voltage and transient photocurrent measurements. The average ideality factor and barrier height has been calculated as 4.2568 and 0.613 eV respectively. The calculated ideality factor for Al/p-Si/Y1-xSrxMnO3/Al diodes is higher than unity because of the interface states, native oxide layer and series resistance. Also, diodes have exhibited property of photosensitivity. These indicated that the fabrication of diodes can be used optoelectronic device applications.     

Efficient production of l-lactic acid from chicken feather protein hydrolysate and sugar beet molasses by the newly isolated Rhizopus oryzae TS-61

The aim of this study was to investigate production of l-lactic acid from molasses and chicken feather protein hydrolysate (CFP) by the newly isolated Rhizopus oryzae TS-61. R. oryzae TS-61 was capable of utilizing molasses sucrose and CFP as carbon and nitrogen sources, respectively. In contrast to yeast extract and ammonium sulfate, CFP had potential not only to prevent excessive pH changes and foaming but also to provide smaller uniform pellet formation in during fermentation. Thanks to these properties, it was concluded that CFP might have resulted in higher l-lactic acid production than the other two nitrogen sources (yeast extract and ammonium sulfate). At the end of 42-h optimal cultivation period, the highest (38.5 g/L) and lowest (28.8 g/L) concentrations of l-lactic acid were obtained with CFP and ammonium sulfate, respectively. This is the first report on use of waste chicken feather as a lactic acid production substrate. In addition, a new R. oryzae strain, being capable of using molasses sucrose as carbon source in order to produce l-lactic acid, was isolated.     

Treatment of dyehouse waste‐water by supercritical water oxidation: a case study

BACKGROUND: Supercritical water oxidation (SCWO) of dyehouse waste‐water containing several organic pollutants has been studied. The removal of these organic components with unknown proportions is considered in terms of total organic carbon concentration (TOC), with an initial value of 856.9 mg L^?1. Oxidation reactions were performed using diluted hydrogen peroxide. The reaction conditions ranged between temperatures of 400–600 °C and residence times of 8–16 s under 25 MPa of pressure. RESULTS: TOC removal efficiencies using SCWO and hydrothermal decomposition were between 92.0 and 100% and 6.6 and 93.8%, respectively. An overall reaction rate, which consists of hydrothermal decomposition and the oxidation reaction, was determined for the hydrothermal decomposition of the waste‐water with an activation energy of 104.12 ( ± 2.6) kJ mol^?1 and a pre‐exponential factor of 1.59( ± 0.5) × 10⁵ s^?1. The oxidation reaction rate orders for the TOC and the oxidant were 1.169 ( ± 0.3) and 0.075 ( ± 0.04) with activation energies of 18.194 ( ± 1.09) kJ mol^?1, and pre‐exponential factor of 5.181 ( ± 1.3) L^0.244 mmol^?0.244 s^?1 at the 95% confidence level. CONCLUSION: Results demonstrate that the SCWO process decreased TOC content by up to 100% in residence times between 8 and 16 s under various reaction conditions. The treatment efficiency increased remarkably with increasing temperature and the presence of excess oxygen in the reaction medium. Color of the waste‐water was removed completely at temperatures of 450 °C and above. Copyright © 2010 Society of Chemical Industry     

Differentiating the natural and man-made terraces of Lake Van, Eastern Anatolia, utilizing earth science methods

The Fertile Crescent of the Middle East region, embracing Syria, eastern Turkey and Iraq, marks the region where settled agriculture began, and where the landscape has been shaped for millennia by human activities. The lacustrine and fluvial terraces of the Late Pleistocene and Holocene Eras are common geomorphic features in many areas around Lake Van in eastern Turkey, being sustainably used since the Urartian Period (800–400 years bc ). Fluctuations in the water levels of Lake Van have resulted in the development of widely distributed natural terraces around the Lake. The undulating slopes of these terraces have limited their cultivation, however, leading people to reconstruct terraces as a means for utilizing particular production sites, as anthroscapes (this concept is generally confined to situations where marked differences or deviations from the normal, natural landscapes are attributable to effects/shaping by humans). The region exhibits semiarid climatic conditions and a short crop‐growing season, currently being under the threat of land degradation. Recent mismanagement of these lands as a result of increasing population pressures has led to the degradation of both the natural and the man‐made terraces. Thus, there is an urgent need to conserve and understand the indigenous management and soil quality attributes of these man‐made terraces. To this end, this study examined soil profiles and analysed soil samples for their chemical, physical and mineralogical characteristics, in order to determine the human effects of leaching and/or accumulation. These analyses revealed significant differences between the physical, chemical, microbiological and mineralogical properties of the man‐made/reworked terraces and natural terraces under essentially similar parent materials and environment, thereby providing clues as to the sustainable management of these land surfaces in eastern Turkey. The approaches used in this study provide useful evidence for attempting to explain the historical evolution of land use in similar environments elsewhere, as well as the significance of terraces in combating coastal erosion in lake environments.