Centralized Scheduling and Priority Implementation Heuristics for a Dynamic Job Shop Model

The problem considered is the scheduling of a job shop with job due dates, intermittent job arrivals, and statistical processing times. Centralized scheduling uses a sequence of static problems for generating priorities at review times. A multi-pass heuristic program, which has proven effective in earlier research, is applied to the up-dated static scheduling problem at each review time. A procedure is proposed for implementing priorities on the shop floor between review times. The procedure is expressly designed to integrate the scheduling of newly arriving jobs to modify the schedule. In simulation experiments using tardiness statistics for evaluation, centralized scheduling and the proposed implementation procedure proved to be an extremely effective combination. Comparison with another procedure that gives the centralized schedule precedence over new arrivals indicates the importance of the implementation procedure when periodic centralized scheduling is used in a dynamic situation.     

Optimum design and operation of batch rectification accompanied by chemical reaction

Batch processes are widespread in the chemical industry. If batch synthesis or separation processes are to run economically, the operating conditions must be optimized and an appropriate arrangement of equipment must be chosen. In this paper, we demonstrate that optimization of operaiong conditions and plant-equipment by simulation during the planning-stages can yield large advantages. In contrast to previous studies, our models include the non-ideal behaviour of multicomponent mixtures and the kinetics of chemical reactions in the column. The results of the calculations are control functions that permit optimum operation to be realized.

As an example, the reactionin a distillation column was optimized. Compared with conventional operation, the calculated control functions give an advantage in capacity of 65% and in energy consumption of 40%. The calculation was confirmed by measurements. A control algorithm is evaluated.     

Simplified high-efficiency silicon cell processing

We developed an emitter diffusion process that yields a near-ideal doping profile with a passivating oxide in a single furnace step. Because this process subjects the material to only one high-temperature thermal excursion, bulk lifetime is better preserved. This is especially true for lower-cost silicon materials containing a high concentration of oxygen or carbon. Using this process, we routinely obtain one-sun cell efficiencies over 19% on float-zone material and over 18% on Czochralski material. Using solar-grade Czochralski material, we have demonstrated record efficiencies of 18.3% at one sun and 20.0% under concentration. Simple processes that yield high-performance diffusion profiles are expected to become increasingly important as manufacturers adopt improved techniques for ohmic contacts.     

Preparing for life: The critical transition of adolescence.

Discusses recent events that have drastically changed the experience of adolescence (e.g., confusion about adult roles and difficulty in foreseeing the future, erosion of family and social support networks) and describes the activities of the Carnegie Council on Adolescent Development to help redress these problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Head Start for the 21st century.

Social and economic conditions since the creation of Head Start in 1965 have worsened. The stresses of economic restructuring in the US and the pervasiveness of violence have severely eroded the capacity of many families to provide safe and caring homes in strong communities. The necessary adaptation of Head Start to these new conditions involves the essential linkage of early childhood and family support approaches with community economic development. This strategy must include a reappraisal of mental health paradigms that will enable children, youth, and families to be healthy and productive members of their neighborhoods and country. Although public support for Head Start remains strong, considerable rethinking about a Head Start for the 21st century is now occurring; results will affect the quality of life for the entire society. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast Bit Gather, Bit Scatter and Bit Permutation Instructions for Commodity Microprocessors

Advanced bit manipulation operations are not efficiently supported by commodity word-oriented microprocessors. Programming tricks are typically devised to shorten the long sequence of instructions needed to emulate these complicated bit operations. As these bit manipulation operations are relevant to applications that are becoming increasingly important, we propose direct support for them in microprocessors. In particular, we propose fast bit gather (or parallel extract), bit scatter (or parallel deposit) and bit permutation instructions (including group, butterfly and inverse butterfly). We show that all these instructions can be implemented efficiently using both the fast butterfly and inverse butterfly network datapaths. Specifically, we show that parallel deposit can be mapped onto a butterfly circuit and parallel extract can be mapped onto an inverse butterfly circuit. We define static, dynamic and loop invariant versions of the instructions, with static versions utilizing a much simpler functional unit. We show how a hardware decoder can be implemented for the dynamic and loop-invariant versions to generate, dynamically, the control signals for the butterfly and inverse butterfly datapaths. The simplest functional unit we propose is smaller and faster than an ALU. We also show that these instructions yield significant speedups over a basic RISC architecture for a variety of different application kernels taken from applications domains including bioinformatics, steganography, coding, compression and random number generation.     

Mechanical and microstructural analysis of geopolymer composites based on metakaolin and recycled silica

This paper evaluated mechanical and thermal stability of alkali-activated materials obtained from metakaolin and alternative silica sources, such as rice husk ash (RHA) and silica fume (SF), and were reinforced with recycled ceramic particles (RP) obtained by grinding bricks. Specimens were produced, and after 7 days of curing, they were exposed to temperatures between 300 and 1200°C to determine the influence that different percentages of RP had on the mechanical behavior and microstructure of the produced composites. The results showed a reduction in the linear contraction by 10.22% with 20 wt% RP and that the reinforcing materials improved the mechanical performance of the geopolymers after exposure to high temperatures; the compressive strengths reached 137.7 (±11.4)  MPa after being exposed to 1200°C for the matrix based on RHA and 180.6 (±19.15) MPa after being reinforced with 20 wt% RP. The improvement was mainly due to densification and the formation of crystalline products such as leucite, kalsilite, and mullite.     

Analytical Modeling for Translating Statistical Changes to Circuit Variability by Ultra-Deep Submicron Digital Circuit Design

This paper presents a physics-based compact gate delay model that includes all short-channel phenomena prevalent at the ultra-deep submicron technology node of 32 nm. To simplify calculations, the proposed model is connected to a compact α-power law-based (Sakurai-Newton) model. The model has been tested on a wide range of supply voltages. The model accurately predicts nominal delays and the delays under process variations. It has been shown that at lower technology nodes, the delay is more sensitive to threshold voltage variations, specifically at the sub-threshold operating region as compared with effective channel length variations above the threshold region.     

Vacuum impregnation of apple slices with Yacon (Smallanthus sonchifolius Poepp. & Endl) fructooligosaccharides to enhance the functional properties of the fruit snack

This work aimed to incorporate prebiotic FOS from yacon in apple slices using vacuum impregnation (VI). Three FOS concentrations (10.3, 14.1 and 18.9 g per 100 g of dry matter (DM)), two temperatures (25 and 35 °C), reuse of extracts and stability of the impregnated slices were evaluated. The highest impregnation level (30.5 g per 100 g DM) was obtained at 35 °C with 14.1% FOS extract while levels of common sugars were reduced. Total phenolics and ABTS antioxidant capacity (AC) slightly decreased while ORAC AC was reduced by 55%. Reuse of the impregnation solution in successive cycles after restoring the FOS level maintained the FOS concentration and profile (GF2–GF7), sugars and phenolic antioxidants. FOS in apple slices remained stable during 4 week storage, while a_w, colour and fracture point changed during storage. This work demonstrated the feasibility of yacon FOS to improve the functional properties of dehydrated apple slices.