Effect of chromium on the mechanical properties of powder-processed Fe–0.45 wt.% P alloys

The present investigation shows the role of chromium in Fe–P binary and Fe–P–Cr ternary alloys. The compositions are characterized in terms of microstructure, porosity content, hardness and tensile properties. The alloys were made using a hot powder forging technique. In this process mild steel encapsulated powders were hot forged into slabs. Then the slabs were hot rolled and annealed to relieve the residual stresses. Densifications as high as 98.9% of theoretical density have been realized. Microstructures of these alloys consist of single-phase ferrite only. Both Fe–0.45P and Fe–0.45P–3Cr alloys showed very high strength. As forged and hot rolled Fe–0.45P alloy showed low elongation. It was observed that, the addition of Cr to Fe–P based alloys caused an increase in strength associated with the reduction in ductility. Alloys developed in the present investigation were capable of hot working to very thin gage of sheets and wires.     

Meyer–Neldel rule in chalcogenide glasses: Recent observations and their consequences

The phenomenon of Meyer–Neldel rule (MNR) can occur in any situation which involves an activated process. However, the rule is still most commonly referred to in connection with diffusion and electrical conduction phenomena. As the rule still tends to exist in an indeterminate state between fully accepted physical law and unexplained correlation, this review presents a survey of relevant work done in this direction. The main objective of the review is to highlight the recent observations of MNR in chalcogenide glasses for different types of thermally activated phenomena and their consequences.     

Calorimetric studies of non-isothermal crystallization in amorphous Cu x Ti100−x alloys

The present paper reports the composition dependence of pre-exponential factor and activation energy of non-isothermal crystallization in amorphous alloys of Cu _x Ti_100?x system using differential scanning calorimeter (DSC) technique. The applicability of Meyer-Neldel relation between the pre-exponential factor and activation energy of non-isothermal crystallization for amorphous alloys of Cu-Ti system was verified.     

Temperature dependence of the relaxation resonance frequency of long-wavelength vertical-cavity lasers

The temperature dependence of the differential gain in AlInGaAs 1310-nm vertical-cavity lasers is investigated. The variations in differential gain and in relaxation resonance frequency are shown to depend on the room-temperature offset between the gain peak wavelength and the wavelength of the lasing mode. The tradeoff between high modulation bandwidth and good high-temperature performance for vertical-cavity lasers is analyzed. A cavity mode that is red-shifted about 25 nm from the gain peak is shown to minimize the variation in modulation bandwidth with temperature, and simultaneously allow for satisfactory high-temperature operation. Experimental results are presented and compared to calculated results with excellent agreement. Because of the change in gain-mode offset with internal temperature, the measured modulation current efficiency changed from about 2 to 4.8 GHz/mA/sup 1/2/ for an increase in drive current from 2 to 10 mA.     

Effect of oil treatments against the infestation of Callosobruchus chinensis (L.) on the levels of B vitamins in stored legumes

Groundnut, coconut and mustard oil treated whole chick pea, mung bean and pigeon pea were infested with Callosobruchus chinensis (L.) and stored for six months. Samples were analysed at monthly intervals for selected B complex vitamins viz. thiamine, riboflavin and niacin. With increase in storage period, values for all the three vitamins decreased in untreated legues. After two months of storage slight decrease in thiamine, riboflavin and niacin content of coconut oil treated legumes was observed which continued till the end of six months as compared to the other two oil treated counterparts. The storage period was associated with insect infestation, which in turn influenced the B complex vitamins of legumes. Groundnut, mustard and coconut oils were able to protect legumes for six months against insect infestation when applied in small amount (0.5%), whereas coconut oil had protective effect against insect infestation only for four months.     

Multicriteria dynamic scheduling by swapping of dispatching rules

For most shop floors, consideration of more than one criterion would be likely to provide more realistic scheduling of a given set of jobs. The present paper considers this aspect of scheduling and uses an algorithm proposed by the authors in their previous work for implementing several criteria simultaneously in a shop of dynamic nature. The algorithm considers several dispatching rules simultaneously for selecting a job for processing and continuously monitors the attained values of performance measures. The selection of dispatching rules is made by identifying the worst performing criterion. A rule that can improve system performance for the worst-performing criterion is selected to dispatch the part under consideration. In this paper, several case studies have been attempted to evaluate the efficiency of the algorithm. The results of the taken case studies indicate that in a dynamic system the system performance improves by changing the dispatching rules corresponding to the worst-performance criterion at the appropriate deterioration in the performance measures.