Minimizing the number of tardy jobs and maximum earliness in the single machine scheduling using an artificial immune system

Nowadays, the importance of timely delivery, which is based on the just in time concept, has caused a number of criteria related to scheduling problems to be taken into consideration. One of the most important of these criteria is maximum earliness to control final costs and number of tardy jobs in an attempt to win customer satisfaction. In this paper, the strongly NP-hard problem of the single machine scheduling with two criteria, i.e., maximum earliness and number of tardy jobs, has been considered. For this purpose, artificial immune system which is inspired by the immunology theory in biology has been used. This algorithm is applied to different instances of small to large sizes and the obtained results is compared with those obtained from a heuristic method and a genetic algorithm reported in the literature. Computational results show a significant preference for the algorithm proposed in this paper.     

Performance analysis of a continuous bioreactor for ethanol and acetate synthesis from syngas via <Emphasis Type="Italic">Clostridium ljungdahlii</Emphasis> using exergy concept

In this paper, the exergetic performance of a continuous bioreactor for ethanol and acetate synthesis from syngas via a strictly anaerobic autotrophic bacterium Clostridium ljungdahlii was carried out for the first time. The fermentation process was evaluated using both conventional exergy and eco-exergy principles for measuring the productivity and renewability of the process at various liquid media flow rates. The microorganisms successfully upgraded the syngas into invaluable ethanol and acetate through the Wood–Ljungdahl pathway. The exergy efficiency was found to be in the range of 6.5–77.5 and 6.8–77.5 % during the fermentation using conventional exergy and eco-exergy concepts, respectively. The subtle differences observed in the exergetic parameters using the two exergetic concepts were ascribed to the slow growth rate of the microorganisms. Nevertheless, the eco-exergy concept would strongly be recommended for commercial bioreactor containing living organisms due to the inclusion of the information carried by microorganisms in the exergetic calculation. A desired liquid media flow rate of 0.55 mL/min was found according to a newly defined thermodynamic indictor namely exergetic productivity index. More specifically, the maximum exergetic productivity index of the fermentation process was found to be 8.0 using both approaches when the rate of inflow liquid was adjusted at the optimal value. The results of this study revealed that process yield alone cannot be a reliable performance metric for decision making on the productivity of various biofuel production pathways. Finally, the proposed exergetic framework could assist engineers and researchers to link biochemical and physical knowledge more robustly and to quantify and elucidate the general purpose of productivity and renewability.     

Synthesis of a novel Zn-MOF/PVA nanofibrous composite as bioorganic material: Design,systematic study and an efficient arsenic removal

Metal organic framework (Zn-MOF)/polyvinyl alcohol (PVA) nanofibrous composite new material has been fabricated using electrospinning and is characterized by a variety of physicochemical analyses, including Fourier transmitting infrared spectroscopy, X-ray powder diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy, nitrogen adsorption surface, and thermo gravimetric-derivative of thermogravimetry. In this study, the effects of a systematic study including a fractional factorial design were studied for arsenic removal. The results showed that although conventional methods have a high level of arsenic removal, the fractional factor method results in a relatively high level of absorption of arsenic. This high level of arsenic removal allows the potential use of nano adsorbents in various environmental fields. The systematic study developed in this study can be used as a novel protocol to eradicate pollution from different areas, including water, air, and soil.     

Trends of biofuel cells for smart biomedical devices

Due to the increasing demand for monitoring diseases such as rising heart rate, diabetes, and ocular disorders wearable and implantable biomedical devices seems too essential for patients not only in the hospital but also at home or during working time. Researchers mostly try to offer valuable information on the conditions of patients as non-invasive, by using comfort biomedical device with a minimum side effect. So, small and self-powered with high sensitivity biomedical devices are recommended, among different power sources that introduced for devices, biofuel cells would be produced as power source for a range of medical devices because of its capability to generate sufficient power output compared to the primary power source. The nature of the electrode reaction and the nature of the biochemical reactions are some of the important parameters that are considered for the classification of fuel cells. Enzymatic biofuel cells due to high activity at mild conditions widely applied in pacemaker; glucometer; and smart contact lenses when compared to other kinds of biofuel cells. On the other hand, short lifespan is one of important limitations in this type of biofuel cells. So, the easiest way to overcome these challenges is to apply non-enzymatic ones. Recent studies have attempted to issue novel method for fabrication of non-enzymatic biofuel cell in order to produce a new generation which are inexpensive, disposable, selective, and sensitive in properties. However, consideration of researchers to the development of self-powered biomedical devices by using body fluids or providing electricity storage is rising.     

Copper (hydr)oxide modified copper electrode for electrocatalytic oxidation of hydrazine in alkaline media

Stable copper (hydr)oxide modified copper electrode was prepared by cyclic voltammetry in 0.1 M NaOH solution in the potential range of −300 to 800 mV. In the first cycle the oxidation peaks of copper were observed but in the second and next cycles, they were omitted and a clean background was obtained. This indicates that an irreversible electrochemical transformation has been achieved during the first cycle and a stable layer of hydr(oxide) formed on the surface of the copper electrode. This layer protects the electrode from corrosion. This electrode can be used for electrochemical studies in the potential range of −300 to 800 mV without any interfering effects by the oxidation peaks of copper. The modified electrode was used for electrocatalytic oxidation of hydrazine. Results showed that on the bare copper electrode the oxidation peak of 10 mM hydrazine appear at 380 mV while on the copper (hydr)oxide modified copper electrode, it appear at 260 mV. About 120 mV negative shift of the peak potential indicated the catalytic activity of (hydr)oxide layer for hydrazine. The kinetic parameters were investigated by using cyclic voltammetry and chronoamperometry.     

Sol–gel synthesis of silicon carbide on silicon pyramids: a promising candidate for supercapacitor electrodes

In this study, Si porous pyramids nanostructures were synthesized by the metal-assisted chemical etching technique. Different KOH concentrations were used to develop high surface area Si porous pyramids for application as supercapacitor electrodes. Field-emission scanning electron microscope (FE-SEM) studies showed that 5% KOH solution will lead to high surface area Si pyramids with a specific capacitance of 90.3 F/cm². Silicon carbide (SiC) thin film was coated on Si pyramids (SiC@Si) using a facile sol–gel method followed by a carbothermal reduction process. Tetraethylorthosilicate and sugar were used as carbon sources. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and FE-SEM analysis were used to characterize the developed SiC@Si samples. The developed SiC@ Si electrode exhibited a high specific capacitance of 135.5 F/cm² at a scan rate of 10 mV/s (in 1 M NaOH electrolyte). The supercapacitor capability of this SiC@Si structure is significantly higher than classical materials. Because of its facile, controllable and efficient synthesis technique, this novel SiC@Si can be considered a very promising candidate for power sources applications.

     

Two-sided assembly line balancing considering the relationships between tasks

Previous studies of the two-sided assembly line balancing problem assumed equal relationships between each two tasks assignable to a side of the line. In practice, however, this relationship may be related to such factors as the distance between the implementation place and the tools required for implementation. We know that the more relationships exist between the tasks assigned to each station, the more efficient will be the assembly line. In this paper, we suggest an index for calculating the value of the relationship between each two tasks, and define a performance criterion called ‘assembly line tasks consistency’ for calculating the average relationship between the tasks assigned to the stations of each solution. We propose a simulated annealing algorithm for solving the two-sided assembly line balancing problem considering the three performance criteria of number of stations, number of mated-stations, and assembly line tasks consistency. Also, the simulated annealing algorithm is modified for solving the two-sided assembly line balancing problem without considering the relationships between tasks. This modification finds five new best solutions for the number of stations performance criterion and ten new best solutions for the number of mated-stations performance criterion for benchmark instances.     

Mathematical models for preemptive shop scheduling problems

More than half a century has passed since Bowman and Dantzig (1959) [13] and [14] introduced their models for preemptive shop scheduling problems. A more efficient model seems to be needed to address all the aspects involved in the problem. We introduce a new Integer Linear Programming (ILP) formulation as a new method for solving the preemptive Job Shop Scheduling Problem (pJSSP). The dimension of the new model, unlike those of the existing ones, depends solely on the number of jobs and machines irrespective of processing times. The proposed model is used as an optimal, two-phase approach. In phase one, the model is solved to obtain the start and completion times of each operation on each machine. In phase two, a simple algorithm in O(mn log n) steps is used to turn these times into a complete and optimal schedule. Different preemptive flow shop problems are studied as special cases of the pJSSP while some related properties are also discussed. Finally, the higher efficiency of the proposed model is verified both theoretically and computationally through its comparison with conventional methods commonly in use.     

Biosynthesis of zinc oxide nanoparticles using anjbar (root of Persicaria bistorta) extract and their cytotoxic effects on human breast cancer cell line (MCF‐7)

Biosynthesis of nanoparticles (NPs) using biomass is now one of the best methods for synthesising NPs due to their nontoxic and biocompatibility. Plants are the best choice among all biomass to synthesise large‐scale NPs. The objectives of this study were to synthesise zinc oxide nanoparticles (ZnO‐NPs) using Anjbar (root of Persicaria bistorta) [An/ZnO‐NPs] and investigate the cytotoxic and anti‐oxidant effects. For this purpose, the An/ZnO‐NPs were synthesised by using Bistort extract and characterised using UV–Visible spectroscopy, transmission electron microscope, field emission scanning electron microscope, x‐ray diffraction and Fourier‐transform infrared spectroscopy. The cytotoxic effects of the An/ZnO‐NPs on MCF‐7 cells were followed by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assays at 24, 48, and 72 h. Nuclear morphology changed and apoptosis in cells was investigated using acridine orange/propodium iodide (AO/PI) staining and flow cytometry analysis. The pure biosynthesised ZnO‐NPs were spherical in shape and particles sizes ranged from 1 to 50 nm. Treated MCF‐7 cells with different concentrations of ZnO‐NPs inhibited cell viability in a time‐ and dose‐dependent manner with IC50 about 32 μg/ml after 48 h of incubation. In flow cytometry analysis the sub‐G1 population, which indicated apoptotic cells, increased from 12.6% at 0 μg/ml (control) to 92.8% at 60 μg/ml, 48 h after exposure. AO/PI staining showed that the treated cells displayed morphologic evidence of apoptosis, compared to untreated groups. Inspec keywords: cancer, cellular biophysics, toxicology, particle size, nanofabrication, X‐ray diffraction, nanomedicine, nanoparticles, ultraviolet spectra, scanning electron microscopy, visible spectra, transmission electron microscopy, patient treatment, field emission electron microscopy, Fourier transform infrared spectra, drug delivery systemsOther keywords: anjbar, cytotoxic effects, human breast cancer cell line, biomass, transmission electron microscope, field emission scanning electron microscope, Fourier‐transform infrared spectroscopy, flow cytometry analysis, ZnO‐NPs inhibited cell viability, antioxidant effects, MCF‐7 cells, biosynthesised ZnO‐NP, biosynthesised ZnO‐NP, acridine orange‐propodium iodide staining, An‐ZnO‐NP, Persicaria bistorta, zinc oxide nanoparticle biosynthesis, 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide     

Computer program for the mass and heat balance calculations for the wet process phosphoric acid (hemi-hydrate) and its applications to Saudi phosphate rock

A computer program is developed for the wet phosphoric acid process using Saudi phosphate ore. The program concentrates on the heart of the process that is the acidulation crystallization step. The key parameters of the program are obtained from micropilot plant continuous experiments performed at our laboratory using different types of Saudi phosphate ores with different chemical, physical and minerological properties. The program is used to correlate the main operating and design parameters with the ore measurable characteristics.