Estimation of ambient temperature impact on vertical dynamic behaviour of passenger rail vehicle with damaged wheels

Maintenance and repair specialists of rolling stock face the problem related to accurate and reliable assessment of the vibrations of the car body of passenger rail vehicle, caused by wheel damage, and its impact on passengers. Another important aspect is to deter-mine the permissible speed at which the passenger car with wheel damage could move to the nearest station or depot without badly damaging the rails. The purpose of this research is to examine the dynamic processes of the interaction of the passenger car chassis with the railway track using a newly developed mathematical models called the “Passenger Car - Track” system. During the simulation, the dynamic characteristics of the track, bogies and car body in different season temperature were estimated. The validation of theoretical results was obtained based on the field tests of the test train as well as the results of measurements of changes in track stiffness temperatures. Finally, conclusions and suggestions are presented.     

The dehydrated VAX-a paradigm for teaching introductory computerengineering

A method used to take advantage of the computer literacy of incoming students and to motivate and enhance a pair of introductory computer engineering courses is described. To carry electrical engineering students from their initial view of a computer as a terminal which understands Fortran to a solid view of what a computing engine does and how to build one, the authors have found it very effective to include a short, intense section on assembly-language programming. The section emphasizes the connection between high-level language programming constructs and machine architecture. To meet the needs of effective material coverage in a five-week segment of the overall two-quarter course, the enormous VAX instruction set was reduced to what looks rather like a reduced instruction set computer (RISC) instruction set of 16 instructions. The instructions selected force full awareness of the details of machine performance and of dynamic memory access and control. By keeping the tool-set small, there is time to concentrate on data structures, internal representations, connections between the high-level language (HLL) and the assembly language expression thereof, and the hardware structures which must underlie computational activity     

Comparative Study on Galvanic-Coupled Intrabody Channel Characteristic Measurement Methods

The galvanic-coupled intrabody communication (GCIBC) uses the human body as the channel for data transmission. The signal flow through different paths within different measurement schemes, resulting in distinct deviations in the experimental results. This method completely uses human body channel to transmit low-power signals, and has good anti-interference performance. However, for a long time, the channel research of GCIBC has not determined a set of recognized and accurate measurement methods and standards. However, few researcher analyze the differences and principles between different measurement methods. This paper aims at three commonly used measurement methods. Abstract the equivalent schematic diagrams of three measurement schemes: direct measurement, using high-precision differential probe and using balun. The signal return paths generated by three measurement methods are analyzed, the impedance matching and energy transmission efficiency are compared. According to the analysis, the empirical expressions in different cases are listed. The mechanism between the channel measurement results generated by the set experimental configuration and the comparison experiment is clarified. The comparison experiment with complete floating measurement is carried out as a reference to verify the proposed opinion. The measurement error caused by different experimental configurations is verified. This study can provide a reference opinions for the experimental error analysis of GCIBC research in the future, and provide suggestions for the selection of experimental configuration.     

Defects in assembly of the extracellular matrix are responsible for altered morphogenesis of a Candida albicans phr1 mutant

The temporal increase of plasma corticosterone (CORT) levels at 3 or 4 days after a single oral administration of trimethyltin (TMT) was suppressed by intracerebroventricular administration of the interleukin-1 receptor antagonist (IL-1ra). On the other hand, glutamate receptor antagonist (MK801) did not affect the TMT-induced CORT level increase. These results indicate that this transient activation of the hypothalamo-pituitary-adrenocortical axis in TMT-treated rats may be in part attributable to the neuroendocrine effects of IL-1 produced by microglia.     

Microwave circuit analysis and design by a massively distributedcomputing network

The advances in microelectronic engineering have rendered massively distributed computing networks practical and affordable. This paper describes one application of this distributed computing paradigm to the analysis and design of microwave circuits. A distributed computing network, constructed in the form of a neural network, is developed to automate the operations typically performed on a normalized Smith chart. Examples showing the use of this computing network for impedance matching and stabilizing are provided     

Investigation of hydrogen generation from sodium borohydride using different cobalt catalysts

Effective Co/Cu, CoB/Cu, and CoBM (M = Mo,Zn,Fe)/Cu catalysts were prepared on the copper surface by a simple electroless deposition method using a morpholine borane as a reducing agent in the glycine solution. The activity of the deposited catalysts was investigated for hydrogen generation from an alkaline sodium borohydride solution. It was determined that these synthesized catalysts demonstrated the catalytic activity for the hydrolysis reaction of NaBH₄. The lowest obtained activation energy (E_A) of the hydrolysis reaction of NaBH₄was 27 kJ mol^?1 for the CoBMo/Cu catalyst. The hydrogen generation rate of 15.30 ml min^?1 was achieved using CoBMo/Cu catalysts at 313 K and it increased ~3.5 times with the increase of temperature to 343 K. The highest hydrogen generation rate obtained by CoBMo/Cu films may be related to the hierarchical cauliflower-shaped 3D structures and the high roughness surface area. Moreover, the CoBMo/Cu catalyst showed an excellent reusability.     

Candida albicans homologue of GGP1/GAS1 gene is functional in Saccharomyces cerevisiae and contains the determinants for glycosylphosphatidylinositol attachment

The GGP1/GAS1/CWH52 gene of Saccharomyces cerevisiae encodes a major exocellular 115 kDa glycoprotein (gp115) anchored to the plasma membrane through a glycosylphosphatidylinositol (GPI). The function of gp115 is still unknown but the analysis of null mutants suggests a possible role in the control of morphogenesis. PHR1 gene isolated from Candida alibicans is homologous to the GGP1 gene. In this report we have analysed the ability of PHR1 to complement a ggp1Δ mutation in S. cerevisiae. The expression of PHR1 controlled by its natural promoter or by the GGP1 promoter has been studied. In both cases we have observed a complete complementation of the mutant phenotype. Moreover, immunological analysis has revealed that PHR1 in budding yeast gives rise to a 75–80 kDa protein anchored to the membrane through a GPI, indicating that the signal for GPI attachment present in the C. albicans gene product is functional in S. cerevisiae.     

Alkali-activated blends of calcined AlF3 production waste and clay

Recently, alkali-activated materials have shown great potential for use in the construction industry. The aim of this research was to study the properties of alkali-activated clay and the effect of incorporating AlF₃ production waste from a fertilizer production plant. The AlF₃ production waste, which was rich in alumina and silica, contributed to improved mechanical behaviour for all the mixtures investigated. This demonstrated the potential for use of this waste material. It was also noted that the dosage of Na₂O, Al₂O₃, and SiO₂ are significant factors that influence the binding mechanism and properties of alkali-activated clay samples. The raw materials, precursors, and alkali-activated samples were investigated by X-ray diffraction, fluorescence spectroscopy, and scanning electron microscopy. The highest compressive strength (17.50?MPa) was observed for alkali-activated clay samples containing 25% AlF₃ production waste, with an increase in compressive strength of up to 64% compared to the samples without the AlF₃ production waste. Deleterious natrite was shown to form in the samples without the production waste, which could be the reason for the lower observed mechanical properties of such samples.     

The spectral element method for elastic wave equations—application to 2‐D and 3‐D seismic problems

A spectral element method for the approximate solution of linear elastodynamic equations, set in a weak form, is shown to provide an efficient tool for simulating elastic wave propagation in realistic geological structures in two‐ and three‐dimensional geometries. The computational domain is discretized into quadrangles, or hexahedra, defined with respect to a reference unit domain by an invertible local mapping. Inside each reference element, the numerical integration is based on the tensor‐product of a Gauss–Lobatto–Legendre 1‐D quadrature and the solution is expanded onto a discrete polynomial basis using Lagrange interpolants. As a result, the mass matrix is always diagonal, which drastically reduces the computational cost and allows an efficient parallel implementation. Absorbing boundary conditions are introduced in variational form to simulate unbounded physical domains. The time discretization is based on an energy‐momentum conserving scheme that can be put into a classical explicit‐implicit predictor/multicorrector format. Long term energy conservation and stability properties are illustrated as well as the efficiency of the absorbing conditions. The accuracy of the method is shown by comparing the spectral element results to numerical solutions of some classical two‐dimensional problems obtained by other methods. The potentiality of the method is then illustrated by studying a simple three‐dimensional model. Very accurate modelling of Rayleigh wave propagation and surface diffraction is obtained at a low computational cost. The method is shown to provide an efficient tool to study the diffraction of elastic waves and the large amplification of ground motion caused by three‐dimensional surface topographies. Copyright © 1999 John Wiley & Sons, Ltd.