A comparative evaluation of assembly line balancing Heuristics

A comparative evaluation is presented of six popular assembly line balancing heuristics, namely, ranked positional weight, Kilbridge and Wester, Moodie and Young, Hoffman precedence matrix, immediate update first fit, and rank and assign heuristic. The evaluation criteria used are the number of excess stations given, line efficiency, smoothness index and CPU time. The trade and transfer phase of the Moodie and Young method is applied to all heuristics, then the results are compared based on the evaluation criteria. Twenty problems each with 5 different cycle times are used for the comparative evaluation of heuristics. All six heuristics are coded in C++ language. Among the six considered heuristics the Hoffmann enumeration procedure performs best; but, the execution time for the Hoffmann procedure is longer because this procedure enumerates all the feasible alternative sets of tasks for the stations. An erratum to this article is available at .     

Numerical Study on Effect of Side Insulation Movement in the Multi-crystalline Silicon Growth Process

Silicon - Numerical simulation is the best tool to understand and optimize the directional solidification (DS) process to grow good quality multi crystalline silicon (mc-Si) ingot for PV...     

Experimental investigations of SiO2 based ferrite magnetic tunnel junction

We report experimental results of ferrite based magnetic tunnel junction. Ferrite junction and spin transport through SiO₂ were interesting since they can readily replace the conventional electronics. We fabricated a cobalt ferrite/SiO₂/cobalt nickel ferrite based magnetic tunnel junction over a copper coated n-silicon substrate using a RF/DC magnetron sputtering. The tunneling magnetoresistance shows a very good response to applied field and we achieved a TMR of about 16%. Although theoretically it was predicted infinite TMR for half metallic ferromagnetic junction, the deviation was explained on the basis of incoherent scattering along the interfaces.     

Accelerated wear testing for evaluating the life characteristics of copper–graphite tribological composite

Sliding wear is a key determinant of the performance of electrical sliding contacts used in electrical machines. The behavior of the contact in sliding couple is controlled by the mutual metal transfer, friction and wear. Product life and reliability of sliding contacts are dictated by wear phenomenon. The present paper focuses on evaluation of tribological performance of copper–graphite composites using reliability theory. These composites are made up of a high electrical and thermal conductivity matrix with a solid lubricant reinforcement, making it most suitable for sliding contacts. Traditional life tests under normal operating condition would be a time consuming process due to a very long expected life of the composite. Hence, accelerated wear testing was carried out for evaluating the life characteristics. Analysis was then performed on the times-to-failure data and reliability models were developed. Life-stress relationship based on the inverse power law-Weibull model was used to make reliability predictions at normal usage level.     

Role of MgO on the HAp forming ability in phosphate based glasses

Phosphate-based glasses 45P₂O₅–30CaO–(25 ? x)Na₂O–xMgO for different compositions of x = 0, 1, 2.5, 5 and 10 mol% were prepared using the normal melt quench technique. To study the influence of MgO on phosphate glasses, a series of experimental analyses such as ultrasonic velocities, differential thermal analysis, X-ray diffraction, energy-dispersive X-ray spectroscopy, pH measurements, Fourier transform infrared spectroscopy, scanning electron microscopy and in vitro studies were carried out in all the prepared glasses. A maxima in ultrasonic parameters at x = 2.5 mol% of MgO content and a further decrease in the same with the addition of MgO content were observed in all glasses. The observed results indicate that structural compactness of glass network took place up to 2.5 mol% of MgO (PCNM2.5), beyond which a loose packing of atoms led to structural softening in glass network. The results obtained from X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy analyses in all glasses before and after in vitro studies revealed the existence of higher HAp-forming ability in PCNM2.5 glass.     

A machinability study of GFRP pipes using statistical techniques

Nowadays, glass fiber reinforced plastics (GFRP) play a vital role in many engineering applications as an alternative to various heavy exotic materials. In GFRP polymeric composites, the matrix of polymer (resin) is reinforced with glass fibers. Such composite pipes are finding applications not only in construction industries, but also in the transportation of corrosive fluid. These pipes are manufactured through hand lay-up or filament winding processes. Though the technology of composite manufacturing is advanced, near-net-shaped components with the required surface finish quality can be achieved only by machining. This paper mainly focuses on the evaluation of the surface finish of the machined surface of GFRP pipes and associated studies. Experiments were conducted through the established Taguchi’s design method. In this work, the machining characteristics are investigated based on surface roughness and tool wear. The machining parameters are also optimized by employing statistical techniques, using the technique of analysis of variance (ANOVA) obtained from regression analysis. Both simple regression and cross product regression methods were employed and their suitability was also studied. An empirical model is also developed to determine the percentage of improvement in tool wear and surface finish. The machined surface exhibited a better surface finish of 4 to 8 microns, whereas the surface roughness of the unmachined surface was observed to be around 80 to 100 microns.     

Solvothermal synthesis of Li3VO4: Morphology control and electrochemical performance as anode for lithium-ion batteries

In this work, orthorhombic Li₃VO₄ with the controllable morphology has been synthesized by tuning the solvent composition (volume ratios of ethanol to deionized water) in a solvothermal approach. The resulting Li₃VO₄ samples with various morphologies (coral-shaped particle, self-assembled hierarchical microsphere, cube-like particle, sheet-like structure) show then different electrochemical performances when employed as anodes for Li-ion battery applications. The Li₃VO₄ with self-assembled hierarchical microsphere morphology (volume ratio of ethanol to deionized water at 15:15) exhibits the best electrochemical performance. The subsequent carbon coating process on microsphere samples is claimed to significantly improve both the capacities at both low (350–430 mAh g^?1 at 100 mA g^?1) and high current (180–350 mAh g^?1 at 2 A g^?1) conditions, and their excellent cycling stability.     

Transient Simulation on the Growth of Mono-like Silicon Ingot in DS Process Using Crucible with Plano-Concave Bottom for PV Applications

Silicon - Two-dimensional numerical simulation on axisymmetric directional solidification furnace has been carried out to investigate the growth of mono-like silicon ingot. The silicon ingots were...     

Effect of Partial Replacement of Retort with an Insulation Material on Mc-Silicon Grown in Directional Solidification Furnace: Numerical Modeling

Silicon - In this paper, the transient global numerical simulation was used in order to study the four types of insulation surrounding the retort within directional solidification furnace which are...     

MnCO3 Cuboids from Spent LIBs: A New Age Displacement Anode to Build High-Performance Li-Ion Capacitors

The advantage of hybridizing battery and supercapacitor electrodes has succeeded recently in designing hybrid charge storage systems such as lithium-ion capacitors (LICs) with the benefits of higher energy than supercapacitors and more power density than batteries. However, sluggish Li-ion diffusion of battery anode is one of the main barriers and hampers the development of high-performance LICs. Herein, is introduced a new conversion/displacement type anode, MnCO₃, via effectively recycling spent Li-ion batteries cathodes for LICs applications. The MnCO₃ cuboids are regenerated from the spent LiMn₂O₄ cathodes by organic acid lixiviation process, and hydrothermal treatment displays excellent reversibility of 535  mAh g⁻¹ after 50  cycles with a Coulombic efficiency of >99%. Later, LIC is assembled with the regenerated MnCO₃ cubes in pre-lithiated form (Mn⁰ + Li₂CO₃) as anode and commercial activated carbon (AC) as the cathode, delivering a maximum energy density of 169.4 Wh kg⁻¹ at 25 °C with ultra-long durability of 15,000 cycles. Even at various atmospheres like −5 and 50 °C, this LIC can offer a energy densities of 53.8 and 119.5 Wh kg⁻¹, respectively. Remarkably, the constructed AC/Mn⁰ + Li₂CO₃-based LIC exhibits a good cycling performance for a continuous 1000 cycles with >91% retention invariably for all temperature conditions.