Thermomechanical Properties of Polypropylene-Based Lightweight Composites Modeled on the Mesoscale

A waste-based particle polymer composite (WPPCs) made of foam glass and polypropylene was developed as a low-cost construction material. Thermomechanical properties of the composite, including creep properties of WPPC and polypropylene binder, were examined. By adding a relatively small amount of polypropylene to foam glass (about 2:8 in volume parts), the maximum bearing capacity at room temperature of the composite increased from 1.9 (pure foam glass) to 15 MPa. A significant creep strain accumulated during compressive loading of WPPC (5 MPa) in the first 2000 s at elevated temperatures (40, 60 °C). In the study, Kafka’s mesomechanical model was used to simulate creep strain changes in time for various temperatures. The applicability of Kafka’s mesomechanical model for simulating creep properties of the studied composite material was demonstrated.     

Retrospective dosimetry with alumina substrate from electronic components

Alumina substrate can be found in electronic components used in portable electronic devices. The material is radiation sensitive and can be applied in dosimetry using thermally or optically stimulated luminescence. Electronic portable devices such as mobile phones, USB flash discs, mp3 players, etc., which are worn close to the body, can represent personal dosemeters for members of the general public in situations of large-scale radiation accidents or malevolent acts with radioactive materials. This study investigated dosimetric properties of alumina substrates and aspects of using mobile phones as personal dosemeters. The alumina substrates exhibited favourable dosimetry characteristics. However, anomalous fading had to be properly corrected in order to achieve sufficient precision in dose estimate. Trial dose reconstruction performed by means of two mobile phones proved that mobile phones can be used for reconstruction of personal doses.     

On-Chip Pseudorandom MEMS Testing

This paper presents a Built-In-Self-Test (BIST) implementation of pseudo-random testing for MEMS. The technique is based on Impulse Response (IR) evaluation using pseudo-random Maximum–Length Sequences (MLS). The MLS approach is capable of providing vastly superior dynamic range in comparison to the straightforward technique using an impulse excitation and is thus an optimal solution for measurements in noisy environments and for low-power test signals. The use of a pseudo-random sequence makes the practical on-chip implementation very efficient in terms of the extra hardware required for on-chip testing. We will demonstrate the use of this technique for an on-chip fast and accurate broadband determination of MEMS behaviour, in particular for the characterisation of cantilever MEMS structures, determining their mechanical and thermal behaviour using just electrical tests.Libor Rufer has received Engineering and PhD degrees from the Czech Technical University, Prague, Czech Republic. Until 1993 he was with the Faculty of Electrical Engineering of the Czech Technical University, Prague and since 1994, he is Associate Professor at the Joseph Fourier University, Grenoble, France. In 1998, he joined the Microsystems research team of the TIMA Laboratory. Currently he is a member of the Reliable Mixed-signal Systems Group of the same Laboratory. His expertise and research interests pertain MEMS-based sensors and actuators, electro-acoustic and electro-mechanical transducers, their modelling, applications, associated measurement techniques, and analogue and mixed-signal system test.Salvador Mir has an Industrial Engineering (Electrical, 1987) degree from the Polytechnic University of Catalonia, Barcelona, Spain, and M.Sc. (1989) and Ph.D. (1993) degrees in Computer Science from the University of Manchester, UK. He is a researcher of Centre National de la Recherche Scientifique, France, and he is leading the RMS (Reliable Mixed-signal Systems) Group at TIMA Laboratory in Grenoble, France. He is the author of many research papers and editor of two books on silicon microsystems. His research interests include analogue, mixed-signal, RF and microsystem design and test, and applications of Artificial Intelligence to Computer-Aided Design.Emmanuel Simeu received Electrical Engineering degree, DEA and Ph.D. in Automatic Control from National Polytechnic Institute of Grenoble in 1987, 1988 and 1992, respectively. He is Associate Professor of Automatic Control and Electrical engineering in Joseph Fourier University of Grenoble. He is also a researcher in the RMS Group at TIMA Laboratory. His research interests include system modelling, reliability of integrated systems, online testing of analogue, digital and mixed signal systems.Christian Domingues was born in Lyon, France, in 1978. He received a Master degree in Microelectronics from the Institut National Polytechnique de Grenoble, France, in 2001. He is currently pursuing a Ph.D. degree at TIMA Laboratory in Grenoble, France. His research interests include mixed-signal integrated circuit design, and micromachined sensors and actuators.     

Competitive Catalytic Hydrogenation in the Liquid Phase on Solid Catalysts

Problems of heterogeneously catalyzed hydrogenation have received increased attention recently. Although the process ranks among those most widely used in the industrial practice, knowledge of it is still inadequate. One of the interesting problems, still also unexplored from the theoretical point of view, concerns competitive catalytic hydrogenations, i.e., reaction systems in which more than one compound react simultaneously. Basically, these systems can be divided into two classes: (1) various functional groups enter the reaction and (2) the reacting functional groups are the same. Competing groups capable of hydrogenation may be contained in one or several molecules.     

Use of patent information at a Czechoslovak research institute

This article describes the patent information services in Czechoslovakia and the use made of patent information in applied research and in patent practice. The various possibilities which exist centrally, regionally and in industry are discussed.     

Comparison of recent rubber-elasticity theories with biaxial stress-strain data: the slip-link theory of Edwards and Vilgis

The Edwards-Vilgis (EV) slip-link theory (1986) derives the elastic free energy of a rubber-like network model containing stable and sliding network junctions (crosslinks and slip-links) and predicts both low-strain softening and high-strain hardening. The four-parameter stress-strain relations calculated by the theory for geometrically different deformation modes up to high strains were tested experimentally using published biaxial stress-strain data on simple covalently crosslinked networks. For networks with low degrees of strain softening and low extensibilities, the experimental dependencies could be described rather well but, generally, a simultaneous satisfactory fit to uniaxial, pure shear and equibiaxial data was not obtained. Systematic experiment-theory deviations exceeding 10% were observed and some of the parameters had a tendency to assume values lying outside the reasonably expected range. The prediction of a pronounced maximum in the strain dependence of stress supported by slip-links seems to be a reason for the discrepancy. Also, modeling of the high-strain singularity in entropy is done in the EV theory using a rather simple approximation. As a result, the finite extensibility contribution to the stress of a slip-link-free network model becomes improbably high and significantly exceeds that following, at a given modulus and locking stretch, from the rigorously derived Langevin-statistics-based eight-chain-network elasticity theory of Arruda and Boyce.     

The catalytic decomposition of 4-phenyl-1,3-dioxan on copper-based catalysts

Transformations of 4-phenyl-1,3-dioxan on copper-based catalysts were investigated in an integral flow reactor in the gas phase in the temperature range 220–280°C. The main products of splitting were 3-phenylpropanal, 3-phenylpropan-1-ol and allylbenzene, and in some cases, styrene. Suitable reaction conditions were sought for the preparation of 3-phenylpropanal and allylbenzene from 4-phenyl-1,3-dioxan.     

Linac Coherent Light Source soft x-ray materials science instrument optical design and monochromator commissioning

We present the x-ray optical design of the soft x-ray materials science instrument at the Linac Coherent Light Source, consisting of a varied line-spaced grating monochromator and Kirkpatrick-Baez refocusing optics. Results from the commissioning of the monochromator are shown. A resolving power of 3000 was achieved, which is within a factor of two of the design goal.     

Visiting convex regions in a polygonal map

This paper is concerned with a variant of the multi-goal path planning in which goals are represented as convex polygons. The problem is to find a closed shortest path in a polygonal map such that all goals are visited. The proposed solution is based on a self-organizing map (SOM) algorithm for the traveling salesman problem. Neurons’ weights are considered as nodes inside the polygonal domain and connected nodes represent a path that evolves according to the proposed adaptation rules. In addition, a reference algorithm based on the solution of the traveling salesman problem and the consecutive touring polygons problem is provided to find high quality solutions of the created set of problems. The problems are designed to represent various inspection and patrolling tasks and can form a kind of benchmark set for multi-goal path planning algorithms. The performance of the algorithms is examined in this problem set, which includes an instance of the watchman route problem with restricted visibility range. The proposed SOM based algorithms provide a unified approach to solve various visibility based routing problems in polygonal maps while they provide a competitive quality of solutions to the reference algorithm with significantly lower computational requirements.