LINEAR PROGRAMMING, SIMULATED ANNEALING AND TABU SEARCH HEURISTICS FOR LOTSIZING IN BOTTLENECK ASSEMBLY SYSTEMS

Multilevel lotsizing is one of the most challenging subjects in production planning, especially in the presence of capacity constraints. In this paper we investigate lotsizing heuristics for assembly production systems with a bottleneck. More specifically, we discuss heuristics based on Linear Programming (LP), and compare the performance of these heuristics with the performance of approaches based on simulated annealing and tabu search techniques.A comparison of the three heuristics on a set of test problems shows that simulated annealing and tabu search perform well compared to pure LP-based heuristics, but the effectiveness of the latter heuristics can be improved by combining them with elements from simulated annealing and tabu search.     

Amorphous microporous mixed oxides as selective redox catalysts

Amorphous microporous homogeneously mixed oxides based on Ti or V in silica can be prepared by an acid catalyzed solgel process. The materials have been characterized by TEM, UV, IR and sorption methods. The glasses can be used for the selective epoxidation of alkenes. The catalytic properties are comparable to those of the well known crystalline Ti-containing zeolites TS-1, Ti-MCM-41 and Ti-Beta. Amorphous microporous homogeneously mixed metal oxides seem to be promising new catalytic materials supplementing the well studied selective zeolites.     

Characterization of Vehicle-to-Vehicle Radio Channels from Measurements at 5.2 GHz

The development of efficient vehicle-to-vehicle (V2V) communications systems requires an understanding of the underlying propagation channels. In this paper, we present results on pathloss, power-delay profiles (PDPs), and delay-Doppler spectra from a high speed measurement campaign on a highway in Lund, Sweden. Measurements were performed at a carrier frequency of 5.2 GHz with the communicating vehicles traveling on the highway in opposite directions. A pathloss coefficient of 1.8 shows the best fit in the mean square sense with our measurement. The average root mean square (RMS) delay spread is between 263 ns and 376 ns, depending on the noise threshold. We investigate and describe selected paths in the delay-Doppler domain, where we observe Doppler shifts of more than 1,000 Hz.     

Weakest preconditions for progress

Predicate transformers that map the postcondition and all intermediate conditions of a command to a precondition are introduced. They can be used to specify certain progress properties of sequential programs.     

A methodology to extract the channel current of permeable gate oxide MOSFETs

A methodology to extract the channel current of MOS transistors in the presence of high gate leakage current is presented. The methodology is based on the partitioning of the gate current among the source and drain terminals and it is well suited for devices featuring ultrathin gate oxide and long channels, as those typically employed for mobility measurements. The proposed procedure is compared with the existing method based on a 50%-50% source/drain partition of the gate current, and the dependence of the extraction error associated with these two methods on channel length and bias conditions is studied in detail. It is found that the extraction error is weakly dependent on gate-source and drain-source voltages.     

System-on-package: a broad perspective from system design to technology development

In this paper, we summarize and analyze main challenges towards system-on-package (SoP) integration with a broad perspective from system design to technology development. We see that the future SoP faces a main challenge of changed system architecture that will be different from today’s personal computer or PC-based systems. It is likely that communication-network based system architectures will be interesting to future SoP platforms. Second, we find that a major paradigm shift will occur in design methodology for SoP integration that emphasizes a coherent co-design of chip, package and system in a mixed signal environment and in combination with new issues such as virtual components integration. On the technology side, the major challenges will be power dissipation and system cooling, low-cost and thermal-matched high-density interconnect substrates, as well as low-cost passive components integration. Finally, we present some research examples that aim to cope with these new challenges on a strategic basis.     

Perceptual use of nonaccidental properties.

Reviews the literature about the nonaccidental properties (NAPs) cotermination, straightness, and parallelism to trace their historical roots, to list the properties that function as NAPs, and to discuss the psychological evidence for their detection and use. Four experiments are reviewed, and four are fully described that were designed to test the perceptual use of skewed symmetry, which results from orthographic projection of planar bilateral or mirror symmetry. Despite the large symmetry advantage obtained in all experiments, skewed symmetry is only perceived as bilateral symmetry-in-depth in cases of closed polygons or dot patterns with higher-order types of symmetry. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Critical evaluation of approaches for on-line batch process monitoring

Since the introduction of batch process monitoring using component models in 1992, different approaches for statistical batch process monitoring have been suggested in the literature. This is the first evaluation of five proposed approaches so far. The differences and similarities between the approaches are highlighted. The derivation of control charts for these approaches are discussed. A control chart should give a fast and reliable detection of disturbances in the process. These features are evaluated for each approach by means of two performance indices. First, the action signal time for various disturbed batches is tested. Secondly, the probability of a false warning in a control chart is computed. In order to evaluate the five approaches, five different data sets are studied: one simulation of a batch process, three batch processes obtained from industry and one laboratory spectral data set. The obtained results for the performance indices are summarised and discussed. Recommendations helpful for practical use are given.     

Chemistry of metapleural gland secretions of three attine ants,Atta sexdens rubropilosa,Atta cephalotes,andAcromyrmex octospinosus (Hymenoptera: Formicidae)

The chemical composition of the secretions of the metapleural glands of workers and soldiers of twoAtta species,Atta sexdens rubropilosa andA. cephalotes, and workers ofAcromyrmex octospinosus, has been studied. As indicated by infrared spectrometry and confirmed by the ninhydrin test, the secretions contain chiefly proteins. Of the volatile acidic portion, which is present as ionized salts, phenylacetic acid is the major component in workers and soldiers ofA. s. rubropilosa andA. cephalotes. BothAtta species also contain 3-hydroxydecanoic acid and its homolog as minor components together with indoleacetic acid. While there are qualitative similarities in the acidic composition in the secretions ofA. s. rubropilosa andA. cephalotes, they differ quantitatively. The secretion ofAcromyrmex octospinosus contains 3-hydroxydecanoic and indoleacetic acids, but lacks phenylacetic acid. The bactericidal and fungicidal actions of the three major substances have been confirmed.