On projection methods,convergence and robust formulations in topology optimization

Mesh convergence and manufacturability of topology optimized designs have previously mainly been assured using density or sensitivity based filtering techniques. The drawback of these techniques has been gray transition regions between solid and void parts, but this problem has recently been alleviated using various projection methods. In this paper we show that simple projection methods do not ensure local mesh-convergence and propose a modified robust topology optimization formulation based on erosion, intermediate and dilation projections that ensures both global and local mesh-convergence.     

On the implementation of bytecode compression for interpreted languages

This paper describes a new method for code space optimization for interpreted languages called LZW‐CC . The method is based on a well‐known and widely used compression algorithm, LZW , which has been adapted to compress executable program code represented as bytecode. Frequently occurring sequences of bytecode instructions are replaced by shorter encodings for newly generated bytecode instructions. The interpreter for the compressed code is modified to recognize and execute those new instructions. When applied to systems where a copy of the interpreter is supplied with each user program, space is saved not only by compressing the program code but also by automatically removing the unused implementation code from the interpreter. The method's implementation within two compiler systems for the programming languages Haskell and Java is described and implementation issues of interest are presented, notably the recalculations of target jumps and the automated tailoring of the interpreter to program code. Applying LZW‐CC to nhc98 Haskell results in bytecode size reduction by up to 15.23% and executable size reduction by up to 11.9%. Java bytecode is reduced by up to 52%. The impact of compression on execution speed is also discussed; the typical speed penalty for Java programs is between 1.8 and 6.6%, while most compressed Haskell executables run faster than the original. Copyright © 2008 John Wiley & Sons, Ltd.     

Design issues of a distance learning course on Business on the Internet

Abstract The paper presents the main design issues of a distance learning course on Business on the Internet. The instructional design is based on a learner-centred instructional strategy which allows learners to construct their own knowledge while solving real business problems and transferring their knowledge to other learners. They learn autonomously taking the responsibility for their learning and following their individual cognitive styles, interests, preferences. The learners have access to the Internet being members of a global, cooperative learning community. The learning community involves students and tutors who collectively take responsibility for the design and evaluation of the course content and the teaching methods to be applied. Both students and tutors inhabit a virtual learning environment that offers different virtual places and services: virtual university, virtual enterprise, auditoriums, workshop rooms, cafes, libraries, etc. where students from different locations can meet, interact, learn and work together, as if they were face-to-face.     

Comparison of the fatty acids of the tunicateBotryllus schlosseri from the Black Sea with two associated bacterial strains

The fatty acid composition of the tunicateBotryllus schlosseri and of two bacterial strains found within the tunicate, namelyVibrio parahaemolyticus and of an associated but previously unreported gram positive cocci were studied. The polyunsaturated fatty acids 6,9,12-octadecatrienoic acid, 5,8,11,14,17-eicosapentaenoic acid, and 4,7,10,13,16,19-docosahexaenoic acid were particularly abundant inB. schlosseri and were not detected in the two bacterial strains found in the tunicate. Theiso/anteiso pair, 13-methyltetradecanoic acid and 12-methyltetradecanoic acid, were the principal fatty acids in the gram positive cocci, and the 9- and 11-hexadecenoic acids were particulary abundant inV. parahaemolyticus. The diunsaturated fatty acid 9,12-octadecadienoic acid was also shown to be present inV. parahaemolyticus. The fatty acid composition of a third bacterial strain, characterized as either aPseudomonas or anAlteromonas species, and shown to be present only in the sea water from the Black Sea and not inB. schlosseri, is also reported. This is the first investigation on fatty acids from Black Sea bacteria.     

Expert system classification of urban land use/cover for Delhi,India

This study presents the results of classifying land use/land cover for Delhi, India using an expert system approach. For this study Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data of 22 September 2003 were used. The research goals of this project are two‐fold. In one respect, the research goal is to report on the extent covered by urbanization using the classified image. Thirteen different land‐cover categories were identified with an 85.55% overall classification accuracy based on 256 random points for validation and 50 on the ground observations. Secondly, we report on our efforts to duplicate an expert system model previously developed for Phoenix Arizona as a generalized approach for urban land use classification. Results suggest that while some of the methodology could be duplicated, there are local factors (e.g. data availability and specific land features) that required the approach to be modified.     

Pressure dependence of the sound velocity in distilled water

The sound velocity is measured in distilled water in the pressure range 0.1–60 MPa and in the temperature range 0–40°C. The results are given in the form of tables and an equation derived by least-squares processing of the experimental data. Translated from Izmeritel'naya Tekhnika, No. 4, pp. 66–69, April, 1999.     

Numerical study of the effect of the doping profile on the threshold voltage of narrow-channel MOS transistor

A two-dimensional MOS process and device simulator, called IMPEDANCE, is used to study the influence of various doping profiles of stopper and channel implantations on the threshold voltage of narrow-channel MOS transistor (made with LOCOS isolation technology). For enhancement-mode transistors without channel implantation the lateral spread of the stopper implantation is the main factor for the threshold voltage increase with decreasing channel width. However the increase of the channel implantation dose reduces the dependence of the threshold voltage on the width especially at higher ion energies. In case of depletion-mode transistors the dependence of the threshold voltage on width is stronger owing to: (1) the existence of a lateral p-n junction between the channel and the stopper region and (2) the weaker gate control of the channel carriers.