Flower-like architecture of CoSn4 nano structure as anode in lithium ion batteries

CoSn₄ nano-particles were synthesized on Cu and Ni substrates through pulsed current electrodeposition and used as anode in lithium ion batteries. Nano particles with Flower-like morphology were obtained through applying an average current density of 85 mA/cm² on Ni substrate while the particles formed using constant current electrodeposition are greater in size ca. 500 nm. Optimum discharge capacity of synthesized CoSn₄ was obtained 848 mAh g^?1 which reduced to 500 mAh g^?1 at 120th cycle indicating an enhanced electrochemical performance compared to anode films synthesized through other pulsed current densities and also constant current electrodeposition. This high discharge capacity and cycleability is attributed to finer crystal grains and flower-like morphology of nano particles. Also, the sample synthesized on Ni substrate showed higher cycleability and noticeably lower resistance. High resistance of anode film synthesized on Cu substrate is due to the corrosion and passivation of copper occurred by HF formation in LiPF₆ electrolyte.     

Solving a multi-floor layout design model of a dynamic cellular manufacturing system by an efficient genetic algorithm

This paper presents a mixed-integer programming model for a multi-floor layout design of cellular manufacturing systems (CMSs) in a dynamic environment. A novel aspect of this model is to concurrently determine the cell formation (CF) and group layout (GL) as the interrelated decisions involved in the design of a CMS in order to achieve an optimal (or near-optimal) design solution for a multi-floor factory in a multi-period planning horizon. Other design aspects are to design a multi-floor layout to form cells in different floors, a multi-rows layout of equal area facilities in each cell, flexible reconfigurations of cells during successive periods, distance-based material handling cost, and machine depot keeping idle machines. This model incorporates with an extensive coverage of important manufacturing features used in the design of CMSs. The objective is to minimize the total costs of intra-cell, inter-cell, and inter-floor material handling, purchasing machines, machine processing, machine overhead, and machine relocation. Two numerical examples are solved by the CPLEX software to verify the performance of the presented model and illustrate the model features. Since this model belongs to NP-hard class, an efficient genetic algorithm (GA) with a matrix-based chromosome structure is proposed to derive near-optimal solutions. To verify its computational efficiency in comparison to the CPLEX software, several test problems with different sizes and settings are implemented. The efficiency of the proposed GA in terms of the objective function value and computational time is proved by the obtained results.     

Safety and immunogenicity of HIV-1 DNA constructs in chimpanzees

A global effort to control the HIV epidemic is likely to rely heavily on immunization strategies. As our closest genetic relative, the chimpanzee provides the most important model for preclinical safety and immunogenicity studies. We have immunized adult, pregnant and infant chimpanzees with our plasmid vaccines. We have found these vaccines to be safe and well tolerated in all of these groups. The same vaccines have induced both humoral and cellular immunity in each instance.     

A multi-objective integrated cellular manufacturing systems design with dynamic system reconfiguration

Cellular manufacturing system (CMS)—an important application of group technology—has been recognized as an effective way to enhance the productivity in a factory. As a result of dynamic deterministic demands within the planning horizon, a CMS configuration for a period might not be optimal or even feasible for other planning periods. Consequently, a multi-objective dynamic cell formation problem is presented, where the total cells load variation and sum of the miscellaneous costs are to be minimized simultaneously. The second objective function calculates machine costs, internal part production, intercellular and intracellular material handling, back order, inventory holding and subcontracting. Since in this type of problem, objectives are in conflict with each other, finding an ideal solution (a solution which satisfies all objectives simultaneously) is not possible. Therefore a non-dominated sorting genetic algorithm (NSGAII) is designed for finding Pareto-optimal frontier that decision maker can select her/his slightly solution. Numerical examples have been solved for demonstrate the efficiency of the proposed algorithm.     

Enhanced hydrogen reversibility of nanoconfined LiBH4–Mg(BH4)2

This study shows the hydrogen desorption kinetics and reversible hydrogen storage properties of 0.55LiBH₄–0.45Mg(BH₄)₂ melt-infiltrated in different nanoporous carbon aerogels with different BET surface areas of 689 or 2660 m²/g and pore volumes of 1.21 or 3.13 mL/g. These investigations clearly show a significantly improved hydrogen storage capacity after four cycles of hydrogen release and uptake for bulk 0.55LiBH₄–0.45Mg(BH₄)₂ and infiltrated in carbon aerogel and the high surface area scaffold, where 22, 36 and 58% of the initial hydrogen content remain after four cycles of hydrogen release and uptake, respectively. Nanoconfinement in high surface area carbon aerogel appears to facilitate hydrogen release illustrated by release of 13.3 wt% H₂ (93%) and only 8.4 wt% H₂ (58%) from bulk hydride in the first cycle using the same physical condition. Notably, nanoconfinement also appear to have a beneficial effect on hydrogen uptake, since 8.3 wt% H₂ (58%) is released from the high surface area scaffold and only 3.1 wt% H₂ (22%) from the bulk sample during the fourth hydrogen release.     

An immune algorithm for hybrid flow shop scheduling problem with time lags and sequence-dependent setup times

This paper deals with hybrid flow shop scheduling problems considering time lags and sequence-dependent setup times which have wide application in real-world problems. Most of the researches on operations scheduling problems have ignored time lags. A mathematical model is presented which is capable of solving the small size of the considered problem in a reasonable time. Since these problems are strongly NP-hard, a meta-heuristic algorithm based on the immune algorithm is developed. The optimization criterion considered in this paper is the minimization of the makespan. Numerical experiments are used to evaluate the performance and effectiveness of the proposed algorithm. The results of the proposed algorithm are compared with the presented mathematical programming model and a benchmark algorithm. Computational results indicate that the proposed algorithm can produce near-optimal solutions in a short computational time. Moreover, it can be applied easily in real factory conditions and for large-sized problems.     

Nanoconfined 2LiBH4–MgH2–TiCl3 in carbon aerogel scaffold for reversible hydrogen storage

Nanoconfinement of 2LiBH₄–MgH₂–TiCl₃ in resorcinol–formaldehyde carbon aerogel scaffold (RF–CAS) for reversible hydrogen storage applications is proposed. RF–CAS is encapsulated with approximately 1.6 wt. % TiCl₃ by solution impregnation technique, and it is further nanoconfined with bulk 2LiBH₄–MgH₂ via melt infiltration. Faster dehydrogenation kinetics is obtained after TiCl₃ impregnation, for example, nanoconfined 2LiBH₄–MgH₂–TiCl₃ requires ∼1 and 4.5 h, respectively, to release 95% of the total hydrogen content during the 1st and 2nd cycles, while nanoconfined 2LiBH₄–MgH₂ (∼2.5 and 7 h, respectively) and bulk material (∼23 and 22 h, respectively) take considerably longer. Moreover, 95–98.6% of the theoretical H₂ storage capacity (3.6–3.75 wt. % H₂) is reproduced after four hydrogen release and uptake cycles of the nanoconfined 2LiBH₄–MgH₂–TiCl₃. The reversibility of this hydrogen storage material is confirmed by the formation of LiBH₄ and MgH₂ after rehydrogenation using FTIR and SR-PXD techniques, respectively.     

A Two Stage Variable-Gain Low-Noise Amplifier for X-Band in 0.18 µm CMOS

In this paper a variable gain low noise amplifier (VG-LNA) is designed and analyzed for X band in 0.18 µm CMOS technology. A two-stage structure is utilized in the proposed VG-LNA and its gain, which is controlled by an on-chip voltage (V_cnt), has continuous and almost linear variations. The required range for V_cnt can be initiated from 0.5 V, also the variations of gain doesn’t ruin reflection loss (S11), return loss (S12) and noise figure (NF). The best performance of this VG-LNA is at 10 GHz frequency with 1 GHz bandwidth. In the center frequency, the maximum gain is 20.8 dB that continuously and linearly decreases to 4 dB by increasing V_cnt. Also S11 and S12 in this frequency are lower than ?27 and ?38 dB, respectively. NF is lower than 2 dB in the mentioned frequency range and NF_min is equal to 1.2 dB, while the third-order intercept point (IIP3) equals to 8.27 dBm in the best condition and always stays above ?10 dBm. The main advantage of the proposed structure in compare with the similar structures is not only the key parameters don’t ruin by the gain variations, but also increment of V_cnt operation range (0.5 V to V_dd), leads to expanding gain control range. These results are achieved while the power consumption is 8.4 mW with 1.8 V supply voltage and the chip area is 0.56 mm².     

A hybrid multi-objective approach based on the genetic algorithm and neural network to design an incremental cellular manufacturing system

One important issue related to the implementation of cellular manufacturing systems (CMSs) is to decide whether to convert an existing job shop into a CMS comprehensively in a single run, or in stages incrementally by forming cells one after the other, taking the advantage of the experiences of implementation. This paper presents a new multi-objective nonlinear programming model in a dynamic environment. Furthermore, a novel hybrid multi-objective approach based on the genetic algorithm and artificial neural network is proposed to solve the presented model. From the computational analyses, the proposed algorithm is found much more efficient than the fast non-dominated sorting genetic algorithm (NSGA-II) in generating Pareto optimal fronts.     

Removal of oil from biodiesel wastewater by electrocoagulation method

An attempt has been made to remove oil and grease (O&G) from biodiesel wastewater as well as O&G and turbidity in the presence of H₂O₂ and polyaluminum chloride (PAC), as a coagulant-aid by an electrochemical method using iron as sacrificial electrodes. The effects of current density, amount of hydrogen peroxide using as an oxidizing agent and addition of coagulant-aid, on percent removal and energy consumption have been investigated. The removal efficiency of O&G was in the range of 62–86%, whereas O&G removal was 100% in the current density range of 10–12.5 mAcm^?2 depending on the concentrations of H₂O₂ and coagulant aid. It is obtained that electrocoagulation in the absence of coagulant aid and oxidant is not too efficient for the treatment of this type of wastewater.