Detailed scheduling of a packing system

Detailed scheduling of a packing system, found in the process industry, is considered. The system consists of a number of packing lines which can pack several products in different formats (sizes). A size/product combination is called an item. Packing rates depend on both item and line. There are minor and major changeovers. The former occur between items of the same size; the latter between sizes. The lines are operated by operators whose number is limited. The number of products that can be packed at the same time in the packing room may be restricted by the number of material handling systems. The objective of the scheduling is to pack item lots dictated by a medium-term planning system so that high packing rates and minimum changeover times are obtained. The problem is formulated as a mixed-integer linear programming problem. The solution procedure is based on searching the solution space with the aid of low bounds derived from solving two subproblems: a machine loading subproblem formulated and solved as a general assignment problem, and a sequencing subproblem formulated and solved as finding the shortest arborescence in a directed network. Penalties to strengthen the low bounds are also devised and used. Case studies to assess the efficiency and efficacy of the scheduling system are presented.     

Social skill training in an integrated preschool program.

This study examined the effectiveness of a commercially available social skills training program plus classroom reinforcement for use with preschoolers with developmental delays. Two groups of 19 participants (mean age 49.73–52.9 mo old) each received either the combined treatment package or classroom reinforcement of target behaviors only. An additional 20 participants served as a control group. The combination of social skills training plus classroom reinforcement of target behaviors resulted in statistically significant increases in sharing behavior over those obtained by both control participants and participants receiving reinforcement of classroom behavior alone. Group behavior was increased over that shown by control participants through the use of either the social skills plus classroom reinforcement treatment package or classroom reinforcement alone. Social skills interventions were viewed favorably by both classroom teachers and preschool participants. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Two-dimensional 8×8 photoreceiver array and VCSEL drivers forhigh-throughput optical data links

Two custom GaAs integrated circuits (ICs) have been developed for enabling vertical cavity surface emitting laser (VCSEL) arrays to be used for high throughput spatial division multiplexed (SDM) optical data links. A 16-channel driver IC was developed to drive the VCSEL array and an 8×8 monolithic photoreceiver, which spatially matches the VCSEL array, was developed for receive. Both of these circuits were fabricated in a standard commercial GaAs MESFET process with parasitic photodetectors used for the photoreceivers. Power dissipation and circuit size were primary design challenges for both circuits. The present 8×8 array size along with an estimated usable channel speed of 1 Gb/s allows for an aggregate throughput of 64 Gb/s     

Solution of fixed cost trans-shipment problems by a branch and bound method

Varied problems in the fields of operation, scheduling, allocation and design in power systems analysis can be formulated as fixed cost trans-shipment problems. This paper indicates possible areas of application of such formulations, and by exploiting specific characteristics of certain power systems problems presents an efficient branch and bound method for solving them.