An integrated scheduling problem of PCB components on sequential pick-and-place machines:mathematical models and heuristic solutions

This paper formulates several mathematical models for determining the optimal sequence of component placements and assignment of component types to feeders simultaneously or the integrated scheduling problem for a type of surface mount technology placement machines, called the sequential pick-andplace (PAP) machine. A PAP machine has multiple stationary feeders storing components, a stationary working table holding a printed circuit board (PCB), and a movable placement head to pick up components from feeders and place them to a board. The objective of integrated problem is to minimize the total distance traveled by the placement head. Two integer nonlinear programming models are formulated first. Then, each of them is equivalently converted into an integer linear type. The models for the integrated problem are verified by two commercial packages. In addition, a hybrid genetic algorithm previously developed by the authors is adopted to solve the models. The algorithm not only generates the optimal solutions quickly for small-sized problems, but also outperforms the genetic algorithms developed by other researchers in terms of total traveling distance.

A heuristic approach for component scheduling on a high-speed PCB assembly machine

The collect-and-place machine is one of the most widely used placement machines for assembling electronic components on the printed circuit boards (PCBs). Nevertheless, the number of researches concerning the optimisation of the machine performance is very few. This motivates us to study the component scheduling problem for this type of machine with the objective of minimising the total assembly time. The component scheduling problem is an integration of the component sequencing problem, that is, the sequencing of component placements; and the feeder arrangement problem, that is, the assignment of component types to feeders. To solve the component scheduling problem efficiently, a hybrid genetic algorithm is developed in this paper. A numerical example is used to compare the performance of the algorithm with different component grouping approaches and different population sizes.

Majority versus minority influence:when, not whether, source status instigates heuristic or systematic processing

Two experiments investigated the extent of message processing of a persuasive communication proposed by either a numerical majority or minority. Both experiments crossed source status (majority versus minority) with message quality (strong versus weak arguments) to determine which source condition is associated with systematic processing. The first experiment showed a reliable difference between strong and weak messages, indicating systematic processing had occurred, for a minority irrespective of message direction (pro- versus counter-attitudinal), but not for a majority. The second experiment showed that message outcome moderates when a majority or a minority leads to systematic processing. When the message argued for a negative personal outcome, there was systematic processing only for the majority source; but when the message did not argue for a negative personal outcome, there was systematic processing only for the minority source. Thus one key moderator of whether a majority or minority source leads to message processing is whether the topic induces defensive processing motivated by self-interest.

Systematic and heuristic processing of majority and minority-endorsed messages:the effects of varying outcome relevance and levels of orientation on attitude and message processing

Two experiments investigated the conditions under which majority and minority sources instigate systematic processing of their messages. Both experiments crossed source status (majority vs. minority) with message quality (strong vs. weak arguments). In each experiment, message elaboration was manipulated by varying either motivational (outcome relevance, Experiment 1) or cognitive (orientating tasks, Experiment 2) factors. The results showed that when either motivational or cognitive factors encouraged low message elaboration, there was heuristic acceptance of the majority position without detailed message processing. When the level of message elaboration was intermediate, there was message processing only for the minority source. Finally, when message elaboration was high, there was message processing for both source conditions. These results show that majority and minority influence is sensitive to motivational and cognitive factors that constrain or enhance message elaboration and that both sources can lead to systematic processing under specific circumstances. © 2007 by the Society for Personality and Social Psychology, Inc.

Rapid heuristic projection on simplicial cones

A very fast heuristic iterative method of projection on simplicial cones is presented. It consists in solving two linear systems at each step of the iteration. The extensive experiments indicate that the method furnishes the exact solution in more then 99.7 percent of the cases. The average number of steps is 5.67 (we have not found any examples which required more than 13 steps) and the relative number of steps with respect to the dimension decreases dramatically. Roughly speaking, for high enough dimensions the absolute number of steps is independent of the dimension.

A new VRPPD model and a hybrid heuristic solution approach for e-tailing

We analyze a business model for e-supermarkets to enable multi-product sourcing capacity through co-opetition (collaborative competition). The logistics aspect of our approach is to design and execute a network system where “premium” goods are acquired from vendors at multiple locations in the supply network and delivered to customers. Our specific goals are to: (i) investigate the role of premium product offerings in creating critical mass and profit; (ii) develop a model for the multiple-pickup single-delivery vehicle routing problem in the presence of multiple vendors; and (iii) propose a hybrid solution approach. To solve the problem introduced in this paper, we develop a hybrid metaheuristic approach that uses a Genetic Algorithm for vendor selection and allocation, and a modified savings algorithm for the capacitated VRP with multiple pickup, single delivery and time windows (CVRPMPDTW). The proposed Genetic Algorithm guides the search for optimal vendor pickup location decisions, and for each generated solution in the genetic population, a corresponding CVRPMPDTW is solved using the savings algorithm. We validate our solution approach against published VRPTW solutions and also test our algorithm with Solomon instances modified for CVRPMPDTW.

Women’s adaptation to STEM domains promotes resilience and a lesser reliance on heuristic thinking

Experiences that compel people to challenge social stereotypes can promote enhanced cognitive flexibility on a range of judgmental domains. Women in STEM (science, technology, engineering, and math) fields are chronically exposed to such experiences and may therefore also demonstrate these benefits. Two studies examined the differential effects of counterstereotypical experiences on women from STEM and non-STEM fields. Results showed that imagining or recollecting these experiences led women from STEM fields to exhibit a lesser reliance on heuristic thinking compared to women from non-STEM fields, and this difference was mediated by self-perceived resilience to the negative impact of gender stereotyping. Implications for psychologists’ and educators’ understanding of the relationship between counterstereotypical experiences and heuristic thinking are discussed.

Some extended psychological benefits of challenging social stereotypes:decreased dehumanization and a reduced reliance on heuristic thinking

One way to promote equality is to encourage people to generate counterstereotypic role models. In two experiments, we demonstrate that such interventions have much broader benefits than previously thoughtreducing a reliance on heuristic thinking and decreasing tendencies to dehumanize outgroups. In Experiment 1, participants who thought about a gender counterstereotype (e.g., a female mechanic) demonstrated a generalized decrease in dehumanization towards a range of unrelated target groups (including asylum seekers and the homeless). In Experiment 2 we replicated these findings using alternative targets and measures of dehumanization. Furthermore, we found the effect was mediated by a reduced reliance on heuristic thinking. The findings suggest educational initiatives that aim to challenge social stereotypes may not only have societal benefits (generalized tolerance), but also tangible benefits for individuals (enhanced cognitive flexibility).