Particle swarm optimization for scheduling batch processing machines in a permutation flowshop

Batch processing machines are capable of processing several jobs in a batch simultaneously. These machines are used in many real-life applications. This paper presents solution approaches to schedule batch processing machines arranged in a permutation flowshop in order to minimize its makespan (or completion time of the last batch). The processing time of each job on all the machines and their sizes are given. Each machine can process a batch of jobs as long as its capacity is not violated. The batch processing time is equal to the longest processing job in the batch. Since the problem under study is NP-hard, commercial mixed-integer solvers may require prohibitively long run time to solve even modest sized problems. Consequently, a particle swarm optimization (PSO) algorithm is proposed. Three heuristics to update the particle’s positions are also proposed. The effectiveness of the proposed PSO algorithm is compared with a commercial solver (which was used to solve a mathematical model) and several heuristics from the literature. The experimental study conducted indicates that the proposed PSO algorithm outperforms both the commercial solver and the heuristics in terms of solution quality. The commercial solver requires longer run times compared to PSO.     

Synthesis and characterization of some new acid salts of 8H-2,6,8,9,10-Pentaazabicyclo[5,2,1]-deca-2,5,9,10-tetraene

Abstract

Some new acid salts of 8H-2,6,8,9,10-pentaazabicyclo[5,2,1]-deca-2,5,9,10-tetraene were prepared and characterised by spectral data (IR, ¹H-NMR and Mass) and elemental analysis. The purity of these compounds was confirmed by HPLC and was found to be > 95% pure. In addition, the compounds were subjected to impact and friction sensitivity tests and were found very safe.     

Axial mixing in a 15 cm diameter reciprocating plate bubble column

Axial dispersion coefficients (E) in the liquid phase have been measured by unsteady tracer response methods in a 15 cm internal diameter reciprocating plate bubble column, using air and water in countercurrent and cocurrent flow. The operating variables studied were amplitude (0.6–1.27 cm) and frequency (0–5 Hz) of reciprocation, and the superficial velocities of the liquid and gas phases and the spacing between plates. Three types of plate were studied; conventional Karr-type plates with perforation diameters 1.43 cm, plates with smaller (0.635 cm) perforations, and single-perforation (doughnut) plates with internal diameter 7 cm. Measured values of E ranged from about 1 cm²/s to a maximum of 116 cm²/s. In general, the plates with 0.635 cm perforations gave the smallest values of E while the largest values of E were obtained with the doughnut plates, due to vortex ring shedding. The single liquid phase data for the three types of plate were approximately consistent with the correlation of Stevens and Baird (1990). The gas-liquid flow results were interpreted in terms of several different hydrodynamic effects.     

Contribution of NMDA and non-NMDA receptors to synaptic transmission from the brachium of the inferior colliculus to the medial subdivision of the medial geniculate nucleus in the rabbit

Previous work from this laboratory has demonstrated that monosynaptic inputs from the brachium of the inferior colliculus (BIC) to the medial subdivision of the medial geniculate nucleus (mMG) strengthen as a result of associative conditioning with an acoustic conditioned stimulus (i.e., fear conditioning). One model that has been proposed to underlie certain types of neuronal plasticity involves the recruitment of N-methyl-D-aspartic acid (NMDA)-type glutamate receptors. The purpose of the present study was to examine the relative contributions of glutamatergic NMDA and non-NMDA receptors to synaptic transmission within this pathway. Individual contributions of the specific receptor types were assessed through the use of 2-amino-5-phosphonovaleric acid (AP5), a selective NMDA receptor antagonist, and 6-cyano-5-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA receptor antagonist. Bipolar stimulating electrodes were stereotaxically implanted in BIC and recording electrodes (attached to dual 32-gauge cannulae for delivery of drug) were positioned in mMG of New Zealand albino rabbits. Single pulses (150 micros, 100-350 microA) delivered to BIC resulted in short-latency (<4 ms) responses in mMG. BIC-evoked single-unit activity was recorded from mMG before, during, and at several intervals after injection of AP5, CNQX, and/or artificial cerebrospinal fluid (ACSF). Injection of either AP5 or CNQX, but not ACSF, significantly attenuated the short-latency BIC-evoked responses in the vast majority of cells tested. These findings suggest that the monosynaptic pathway from BIC to mMG is glutamatergic and that this pathway frequently employs NMDA-type receptors during electrically stimulated synaptic transmission. Due to the NMDA receptors' proposed role in plasticity (e.g., long-term potentiation), these results may have implications for understanding the mechanisms of synaptic plasticity observed at this synapse during associative learning.     

Growth and Optical Properties of Quantized CdS Crystallites in TEOS Silica Xerogels

Quantized CdS crystallite-doped tetraethylorthosilicate (TEOS) silica xerogels are prepared by the sol-gel method. In this method, cadmium acetate [Cd(CH₃COO)₂2H₂O]-doped TEOS alcogel is formed by the hydrolysis and polycondensation of ethanolic TEOS in the presence of hydrochloric acid (HCl) and ammonium hydroxide (NH₄OH) catalysts and Cd(CH₃COO)₂.2H₂O. The CdS crystallites are formed in the alcogel by the reaction of Cd(CH₃COO)₂.2H₂O present in the gel and methanolic sodium sulfide (Na₂S), which is added over the alcogel. The effect of CdS/TEOS, EtOH/TEOS, S/Cd molar ratios, and temperature on the optical properties and CdS crystallite sizes in the xerogels are studied. A blue shift is observed in optical absorption spectra by decreasing the CdS/TEOS molar ratio from 2 × 10^–2 to 1 × 10^–4. It is observed that the crystallite size is increased from 1.6 to 3.4 nm by increasing the EtOH/TEOS molar ratio from 2 to 20, respectively, for a constant CdS/TEOS molar ratio of 5 × 10^–4. Emission spectra of xerogels are measured and found that the emission peak maxima shifted toward lower energies (higher wavelengths) by increasing the CdS/TEOS molar ratio in the xerogels. It is known from the X-ray diffraction (XRD) measurements of CdS-doped xerogels that the CdS crystallite structure in the xerogels is hexagonal wurtzite. The crystallite sizes were calculated from the XRD patterns and tight bonding calculations. There is a significant change in the color and size of CdS crystallite in the xerogels with a variation in temperature from 200 to 400°C.     

8 MeV electron irradiation studies on electrical characteristics of Cu(In,Ga)Se2 solar cells

Cu(In,Ga)Se₂ (CIGS) solar cells are gaining considerable interest due to their high optical absorption coefficient and adjustable band gap, which enables them to achieve high conversion efficiency and also present many promising applications in space power systems. In this paper we report the results of the effect of temperature and 8 MeV electron irradiation on the electrical characteristics of ZnO/CdS/Cu(In,Ga)Se₂/Mo polycrystalline thin-film solar cells under forward and reverse bias studied in the temperature range 270-315 K. The solar cells were subjected to 8 MeV electron irradiation from the Microtron accelerator and were exposed to graded doses of electrons up to 75 kGy. I-V characteristics of the cells under dark and AM 1.5 illumination condition were studied before and after the irradiation. Capacitance measurements were also carried out at various frequencies before and after irradiation. In the measured temperature range, the dark current contribution is due to the generation-recombination of the minority carriers in the depletion region. The ideality factor is found to decrease with increase in temperature. It seems that electron irradiation has not altered the dark current conduction mechanism significantly. The effect of electron irradiation on the solar cell parameters such as fill factor (FF), conversion efficiency (η), saturation current (I_o), short circuit current (I_sc), open circuit voltage (V_oc), and ideality factor (n) was studied. They were found to be stable up to 75 kGy of electron dose as only small changes were observed in the solar cell parameters.     

Discharge Characteristics of Polydisperse Powders through Conical Hoppers. Part 2: Predictions for Coarse,Granular, Free Flowing Powders

Abstract

The tribo/contact electrification theory of materials is envisaged from the chemical Lewis acid-base concept and an attempt has been made to find a correlation between these two phenomena. The donor-acceptor/acid-base properties of apatite, calcite, feldspar, quartz and wollastonite mineral samples have been determined by electrokinetic studies in water and in different organic solvents having different donicity values. From the results, the donicity values for mineral samples were defined and the position of Fermi level in the forbidden gap energy was estimated. The charge acquired by a single mineral particle of varying sizes was determined after contacting with plate and cyclone type tribochargers made up of different materials. The work functions of the mineral samples were estimated.

The results showed a good correlation between the physical tribo-electrification process and the chemical acceptor-donor property of the minerals. The results also demonstrate the feasibility of arranging the minerals into triboelectric series and thereby to predict their triboelectric charge characteristics and their separation behavior in an electric field with reference to a particular tribocharger medium.