A mathematical model and solution methods for rail freight transportation planning in an Indian food grain supply chain

This paper addresses the rail transportation of food grains undertaken by Food Corporation of India (FCI) to meet the requirements of the food security programme called Public Distribution System (PDS). The research focuses on improving the allocation of railway rakes transporting food grains to a set of storage warehouses. A penalty factor based approach is adopted to represent the considerations in transportation planning and three penalty factors such as rake penalty factor, weekly penalty factor and capacity utilization penalty factor are introduced for the purpose. The single source - multiple destination problem is formulated and solved using exact method to minimize the sum of these three penalty factor values, termed total penalty. Further, a heuristic named optimum rake allocation algorithm is developed and tested using a set of 35 problem instances. The proposed heuristic is found to be highly efficient in terms of solution quality and computation time. A case study of FCI Kerala Region is also carried out to validate the formulated model and the proposed heuristic. The work provides valuable insights into the practical issues encountered in rail freight transportation planning and proposes an effective solution methodology to address them.     

配给能源采集供电:无线传感器节点的功率约束

让周遭的系统能够自动感测环境变化并做出反应，势必将对于人类的生活造成重大改变。无线传感器网络是多个分布式传感器实作（节点）组成的系统，能够共同透过相互无线通信的方式响应实体变化。本文将重点介绍节点的最新进展，并推广对于系统层级设计方法的需求。     

New approach for prediction of influence of vehicle dynamics parameters on instability of unmanned track vehicle using robotic approach

Journal of Mechanical Science and Technology - Achieving stability of unmanned, heavy tracked vehicles is challenging, especially under conditions of teleoperation because the remote operator...     

Hydrodynamic behavior of inverse fluidized bed biofilm reactor for phenol biodegradation using Pseudomonas fluorescens

The hydrodynamic characteristic performance of an internal draft tube inverse fluidized bed biofilm reactor was studied for the aerobic biodegradation of phenol (1,200 mg/l) using Pseudomonas fluorescens for various ratios of settled bed volume to reactor working volume (V _b /V _r ) under batchwise condition with respect to liquid phase. The operating parameters, such as superficial gas velocity, phase hold ups, aspect ratio and bed height, were analyzed for different ratios of (V _b /V _r ). The effect of biodegradation on synthetic phenolic effluent was determined from the reduction in chemical oxygen demand and phenol removal efficiency. The optimum value of (V _b /V _r ) _m was 0.20 for the optimal superficial gas velocity, U _gm =0.220 m/s with the COD reduction efficiency of 98.5% in 48 hours. The biomass and biofilm characteristics of P. fluorescens were determined for optimal hydrodynamic operating parameters by evaluating its biofilm dry density and thickness, bioparticle density, suspended and attached biomass concentration.     

Revisable knowledge discovery in databases

This article introduces the idea of using nonmonotonic inheritance networks for the storage and maintenance of knowledge discovered in data (revisable knowledge discovery in databases). While existing data mining strategies for knowledge discovery in databases typically involve initial structuring through the use of identification trees and the subsequent extraction of rules from these trees for use in rule-based expert systems, such strategies have difficulty in coping with additional information which may conflict with that already used for the automatic generation of rules. In the worst case, the entire automatic sequence may have to be repeated. If nonmonotonic inheritance networks are used instead of rules for storing knowledge discovered in databases, additional conflicting information can be inserted directly into such structures, thereby bypassing the need for recompilation. © 1996 John Wiley & Sons, Inc.     

Crystalline selenite substituted carbonated hydroxyapatite nanorods: Synthesis,characterization, evaluation of bioactivity and cytotoxicity

Synthesis of pure and selenite substituted hydroxyapatites (HAP and Se‐HAP with 0.02–0.10 Se) by sol–gel method and evaluation of their morphological features, nature of functional groups, phase purity, in vitro bioactivity and cytotoxicity are addressed. Spectral studies confirm the incorporation of selenite into the HAP lattice, accompanied by an increase in CO₃^2? content to maintain the charge imbalance following replacement of P⁵⁺ with Se⁴⁺, thus making the formation of selenite substituted carbonated HAP. Selenite substitution in the HAP lattice has led to a higher crystallinity and increased the crystallite size. The morphology of HAP is changed from sphere to rod‐like structure upon substitution by selenite and the size of the rod is increased with an increase in the selenite content. Among the Se‐HAPs, a better in vitro bioactivity and cell viability are observed for 0.02 Se‐HAP and 0.04 Se‐HAP while the trend is reversed when the extent of selenite substitution becomes higher.     

Response of alkali activated fly ash mortars to microwave curing

Volumetric heating provided by microwave curing results in faster property development as compared to conventional heat curing that relies on heat conduction from the skin to the core. This paper discusses the compressive strength and microstructure development of microwave cured NaOH activated fly ash mortars, and relates them to the microwave energy absorption by the material which is a function of its dielectric properties. Microwave curing parameters are chosen so as to eliminate the effects of thermal runaway. Strengths that are comparable to or greater than those of mortars heat cured for 48 h at 75 °C are obtained in less than 120 min of microwave curing. The rate of energy absorption by the mortars is found to be relatively constant for a considerable fraction of the microwave curing duration, attributable to the compensation for the drop in dielectric loss factor as a result of moisture loss by the increase in internal electric field. Compressive strength is shown to be related to the microwave energy absorbed by the specimens, especially during the time when free water is present in the system.     

锌-三氧化二铬复合镀层的特性

采用由氧化锌12g/L、氢氧化钠94 g/L、2-氨基-3-羧基吡啶4.2 g/L、四乙烯五胺17g/L、三乙醇胺2g/L、专利表面活性剂0.5 g/L及碳三氧化二铬(粒径2μm)0～ 11 g/L组成的镀液,于温度50℃、pH 6.5和电流密度4A/dm2的条件下,在低碳钢上电镀Zn-Cr2O3复合镀层.其显微硬度采...     

Fretting corrosion of tin-plated contacts

The susceptibility of tin-plated contacts to fretting corrosion is a major limitation for its use in electrical connectors. The present paper evaluates the influence of a variety of factors, such as, fretting amplitude (track length), frequency, temperature, humidity, normal load and current load on the fretting corrosion behaviour of tin-plated contacts. This paper also addresses the development of fretting corrosion maps and lubrication as a preventive strategy to increase the life-time of tin-plated contacts. The fretting corrosion tests were carried out using a fretting apparatus in which a hemispherical rider and flat contacts (tin-plated copper alloy) were mated in sphere plane geometry and subjected to fretting under gross-slip conditions. The variation in contact resistance as a function of fretting cycles and the time to reach a threshold value (100 mΩ) of contact resistance enables a better understanding of the influence of various factors on the fretting corrosion behaviour of tin-plated contacts. Based on the change in surface profile and nature of changes in the contact zone assessed by laser scanning microscope (LSM) and surface analytical techniques, the mechanism of fretting corrosion of tin-plated contacts and fretting corrosion maps are proposed. Lubrication increases the life-time of tin-plated contacts by several folds and proved to be a useful preventive strategy.