Analysis of partial setup strategies for solving the operational planning problem in parallel machine electronic assembly systems

In this paper, we analyse the operational planning problem in an electronic assembly system with multiple placement machines operating in parallel. The partial setup strategy is proposed as an effective methodology for this problem. This strategy attempts to determine the balance between processing time and changeover time during system operation. The Tour primary issues are determining the assignment of products to machines, the sequence of products on each machine, the assignment of components to feeder locations for each product, and the component placement sequence for each product. Four solution procedures for unique and partial setup strategies are developed and tested. The computation results show that for low to medium volume high mix environments, the partial setup procedures offer significant improvement over the unique setup strategies. The results also show that no single fixed strategy dominates in all scenarios, and therefore, an adaptable procedure that will choose the best solution for each set of requirements is needed.     

The asymmetric lossy near-perfect lens

We extend the ideas of the perfect lens recently proposed [J.B. Pendry, Phys. Rev. Lett. 85, 3966 (2000)] to an alternative structure. We show that a slab of a medium with negative refractive index bounded by media of different positive refractive index also amplifies evanescent waves and can act as a near-perfect lens. We examine the role of the surface states in the amplification of the evanescent waves. The image resolution obtained by this asymmetric lens is more robust against the effects of absorption in the lens. In particular, we study the case of a slab of silver, which has a negative dielectric constant, with air on one side and other media such as glass or GaAs on the other side as an ‘asymmetric’ lossy near-perfect lens for p-polarized waves. It is found that retardation has an adverse effect on the imaging due to the positive magnetic permeability of silver, but we conclude that subwavelength image resolution is possible in spite of it.     

Composite supercapacitor electrodes made of activated carbon/PEDOT:PSS and activated carbon/doped PEDOT

In this paper, we report on the high electrical storage capacity of composite electrodes made from nanoscale activated carbon combined with either poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) or PEDOT doped with multiple dopants such as ammonium persulfate (APS) and dimethyl sulfoxide (DMSO). The composites were fabricated by electropolymerization of the conducting polymers (PEDOT:PSS, doped PEDOT) onto the nanoscale activated carbon backbone, wherein the nanoscale activated carbon was produced by ball-milling followed by chemical and thermal treatments. Activated carbon/PEDOT:PSS yielded capacitance values of 640 F g^?1 and 26 mF cm^?2, while activated carbon/doped PEDOT yielded capacitances of 1183 F g^?1 and 42 mF cm^?2 at 10 mV s^?1. This is more than five times the storage capacity previously reported for activated carbon–PEDOT composites. Further, use of multiple dopants in PEDOT improved the storage performance of the composite electrode well over that of PEDOT:PSS. The composite electrodes were characterized for their electrochemical behaviour, structural and morphological details and electronic conductivity and showed promise as high-performance energy storage systems.     

Globalization and the Undergraduate Manufacturing Engineering Curriculum

At an ASME panel on manufacturing engineering education, industry representatives emphasized preparation for globalization. The concept has not yet had widespread impact on undergraduate engineering curricula. In this paper the industry updates are summarized, especially as they pertain to undergraduate engineering education for a globalized economy, and synthesized with the literature on the subject. Objectives for manufacturing engineering education are derived and possible ways of introducing the subject into an undergraduate curriculum without lengthening the program are suggested. The findings should be applicable to manufacturing, mechanical, and industrial engineering.     

Volatiles Retention as Influenced by Method of Addition during Extrusion Cooking

Normal corn starch with 15 to 21% (db) moisture content was extrusion-cooked in a twin-screw extruder. Cinnamaldehyde, nonanoic acid, 3-octanone and eugenol, at concentrations of 1 to 5% (w/w), were either premixed with the feed or injected into the barrel. Response surface methodology was used to predict percent initial amount retained. Radial expansion ratios were different when volatile components were premixed with the feed for all components except 3-octanone. Only nonanoic acid influenced (P > F = 0.001) specific mechanical energy values due to the method of addition. Volatile component retention was enhanced when they were injected into the extruder barrel as compared to pre-mixing with the feed.     

Study of seasonal current variability in the Arabian Sea using Geosat altimeter data

The study of ocean circulation is required in climatic research, weather forecasting, navigation etc. Studying this phenomenon over larger spatial and temporal scales by conventional methods is very difficult. The advent of satellite altimetry gave ample opportunity to study ocean circulation repeatedly over larger areas. In this study Geosat altimeter derived sea level observations have been used to obtain monsoon departure current vectors over the Arabian Sea using geostrophic approximation. Current variability on the annual and seasonal bases is also studied. The circulation features are of the expected order. However, the departure current speeds near the Somali region are underestimated due to the limitation of the data. High current variabilities are present at places where large variations in current magnitude prevail.     

Investigations on Flowsheet Development for the Treatment of Niobium-Tantalum Bearing Cassiterite

Abstract

The paper presents the results of experimental investigations carried out for developing a flowsheet for the treatment of niobium-tantalum bearing cassiterite containing about 23%of mixed niobium and tantalum oxide. Three different approaches viz. direct smelting of cassiterite to tin metal and niobium-tantalum bearing slag, reduction roasting-acid leaching and alkali fusion-leaching to separate tin from niobium-tantalum followed by recovery of tin as oxide and finally carbothcrmic reduction to tin metal have been examined on laboratory scale. It has been observed that alkali fusion—leaching—tin oxide smelting is quite attractive to obtain a good purity tin metal and also recover niobium and tantalum as mixed oxides.     

Functional Properties of Guar Seed (Cyamopsis tetragonoloba) Meal Detoxified by Different Methods

Functional properties of guar meal detoxified by autoclaving, extraction with aqueous ethanol, methanol, isopropanol or dilute hydrochloric acid were compared with those of defatted soy meal. Acid washed and the autoclaved meals gave low nitrogen solubility (NS) at pH 7.0. Detoxified guar meals had greater water absorption capacity (WAC) than the raw meal, while defatted soy meal was far superior to defatted guar meal. Fat emulsification capacity (EC) showed a similar trend as NS and fat absorption capacity (FAC) inversely correlated with the bulk density of samples. Autoclaved guar meal had higher EC and FAC than the alcohol or acid extracted meals. The foam capacity (FC) and foam stability (FS) of the 80% isopropanol extracted guar meal were the highest among the samples.