Pd-Si binary bulk metallic glass

Pd_80+x Si_20−x (x = 0, 1, and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content, the glass transition temperature T _g, the initial crystallization temperature T _x and the onset crystallization temperature T _p of Pd-Si binary glassy alloys increase. Moreover, the supercooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability, which can be greatly improved by fluxing treatment. Supported by the National Basic Research Program of China (Grant No. 2007CB613905) and the National Natural Science Foundation of China (Grant Nos. 50671050 and 50431030)     

Brane Cosmology, Varying Speed of Light and Inflation in Models with One or More Extra Dimensions

We summarize the approach to brane cosmology known as mirage cosmology and use it to determine the Friedmann equation on a 3-brane embedded in different bulk spacetimes all with one or more extra dimensions. Usually, when there is more than one extra dimension the junction conditions, central to the usual brane world scenarios, are difficult to apply. This problem does not arise in mirage cosmology because the brane is treated as a test particle in the background spacetime. We discuss in detail the dynamics of a brane embedded in two specific 10D bulk spacetimes, namely Sch-AdS₅ × S₅ and a rotating black hole, and from the dynamics—which are now rather more complicated since the brane can move in all the extra dimensions—determine the new dark fluid terms in the brane Friedmann equation. Some of these, such as the cosmological constant term, are seen to be bulk dependent. We then show explicitly how this mirage cosmology approach matches with the familiar junction condition approach when there is just one extra dimension. The issue of a varying speed of light in mirage cosmology is addressed and we find a scenario in which c _eff always increases, tending asymptotically to c ₀ as the universe expands. Finally some comments are made regarding brane inflation and limitations of the mirage cosmology approach are also discussed.     

Nonlinear optical characterization of cluster dynamic in water in oil microemulsion by a pump probe laser beam technique

We present a new pump probe laser beams configuration for the nonlinear optical characterization of microemulsions. We detect the variation of the on-axis optical intensity of the probe beam as generated by the concentration profile induced in an optically thin film of microemulsion by the pump beam. A mathematical model has been introduced to describe the phenomenon. The technique allows the determination of both Kerr-like optical nonlinearity and time constants and, therefore, it gives information both on cluster dimension and their shape. We discuss its application to WAD (water/AOT/decane, where AOT denotes sodium-bis-di-ethyl-sulfosuccinate) with the application of a strong electric field of optical source. Comparison between theoretical predictions and experimental results confirms the presence of giant optical nonlinearity in the absence of turbidity divergence. Chainlike shape of clusters, of the kind already reported with the application of strong electric field, could justify this result. Received 26 October 2002 RID="a" ID="a"e-mail: vicari@na.infn.it     

一种体声波滤波器仿真设计分析

文中着重阐述了基于微机电系统（Micro-Electro-Mechanical Systems，MEMS）技术制造的薄膜体声波谐振器／滤波器，简述了它的结构及原理，分析了其主要特征参数和设计方法，并设计了中心频率为2．4GHz，带宽为100MHz的带通滤波器，展示了薄膜体声波谐振器／滤波器的突出性能，为通信MEMS技术的微型化发展提供了更广阔的道路。     

声表面波器件中非同步区域体波散射的抑制

用有限元/边界元法(FEM/BEM)研究了表面波器件中非同步区域中体波散射引起的损耗。以典型的hiccup单端对谐振器作参考结构,用结构参数缓慢变化的间隙取代其中间的自由间隙。研究发现,改变间隙参数可在保持谐振频率不变的同时,提高谐振器的品质因数值。对分布间隙和风琴间隙两种间隙结构进行对比,结果表明,前者优于后者。将传统DMS滤波器中的金属化间隙以分布间隙取代,可找到一个优化的分布间隙结构,使插损提高0.3 dB。     

Functional Analysis of Tube Chain Conveyors

This paper describes some of the aspects necessary for the design and use of tube chain conveyors. It is based on the reports of experienced experts and recent tube chain conveyor experimental results. The aim of the research work is the formulation of general technical regulations for tube chain conveyors. Theoretical models were developed, which allow the calculation of the motion resistances in all parts of the conveyor by the use of empirical extracted correction factors. Specially designed measurement equipment enabled the measurement of the important chain tractive force from the closed tube system. The measurements show the influence of the major operational parameters and the bulk solid properties.     

Behavioral-Level Performance and Power Exploration of Data-Intensive Applications Mapped on Programmable Processors

The continuous increase of the computational power of programmable processors has established them as an attractive design alternative, for implementation of the most computationally intensive applications, like video compression. To enforce this trend, designers implementing applications on programmable platforms have to be provided with reliable and in-depth data and instruction analysis that will allow for the early selection of the most appropriate application for a given set of specifications. To address this need, we introduce a new methodology for early and accurate estimation of the number of instructions required for the execution of an application, together with the number of data memory transfers on a programmable processor. The high-level estimation is achieved by a series of mathematical formulas; these describe not only the arithmetic operations of an application, but also its control and addressing operations, if it is executed on a programmable core. The comparative study, which is done using three popular processors (ARM, MIPS, and Pentium), shows the high efficiency and accuracy of the methodology proposed, in terms of the number of executed (micro-)instructions (i.e. performance) and the number of data memory transfers (i.e. memory power consumption). Using the proposed methodology we estimated an average deviation of 23% in our estimated figures compared with the measurements taken from the real execution on the CPUs. This work was supported by the project PENED ’99 ED501 funded by GSRT of the Greek Ministry of Development, and the project PRENED ’99 KE 874 funded by the Research Committee of the Democritus University of Thrace. This work was partially sponsored by a scholarship from the Public Benefit Foundation of Alexander S. Onassis (Minas Dasygenis). Nikolaos Kroupis was born in Trikala in 1976. He receiver the engineering degree and Ms.C. degree in Department of Electrical and Computer Engineering from Democritous University of Thrace, Greece, in 2000 and 2002, respectively. Since 2002 he has been a Ph.D. student at the Laboratory of Electrical and Electronic Materials Technology. His research interests are in software/hardware co-design of embedded system for signal processing applications. Nikos D. Zervas received a Diploma in Electrical & Computer Engineering from University of Patras, Greece in 1997. He received the Ph.D. degree in the Department of Electrical and Computer Engineering of the same University in 2004. His research interests are in the area of high-level, power optimization techniques and methodologies for multimedia and telecommunication applications. He has received an award from IEEE Computer Society in the context of Low-Power Design Contest of 2000 IEEE Computer Elements Mesa Workshop. Mr. Zervas is a member of the IEEE, ACM and of the Technical Chamber of Greece. Minas Dasygenis was born in Thessaloniki in 1976. He received his Diploma in Electrical and Computer Engineering in 1999, from the Democritus University of Thrace, Greece, and for his diploma Thesis he was honored by The Technical Chamber of Greece and Ericsson Hellas. In 2005, he received his PhD Degree from the Democritus University of Thrace. His research interests include low-power VLSI design of arithmetic circuits, residue number system, embedded architectures, DSPs, hardware/ software codesign and IT security. He has published more than 20 papers in international journals and conferences and he has been a principal researcher in three European research projects. Konstantinos Tatas received his degree in Electrical and Computer Engineering from the Democritus University of Thrace, Greece in 1999. He received his Ph.D. in the VLSI Design and Testing Center in the same University by June 2005. He has been employed as an RTL designer in INTRACOM SA, Greece between 2000 and 2003. His research interests include low-power VLSI design of DSP and multimedia systems, computer arithmetic, IP core design and design for reuse. Antonios Argyriou received the degree in Electrical and Computer engineering from the Democritous University of Thrace, Greece, in 2001, and the M.S. and Ph.D. degrees in Electrical and Computer engineering from the Georgia Institute of Technology, Atlanta, in 2003 and 2005, respectively. His primary research interests include wireless networks, mobile computing and multimedia communications. He is a member of the IEEE and ACM. Dimitrios Soudris received his Diploma in Electrical Engineering from the University of Patras, Greece, in 1987. He received the Ph.D. Degree in Electrical Engineering, from the University of Patras in 1992. He is currently working as Ass. Professor in Dept. of Electrical and Computer Engineering, Democritus University of Thrace, Greece. His research interests include low power design, parallel architectures, embedded systems design, and VLSI signal processing. He has published more than 140 papers in international journals and conferences. He was leader and principal investigator in numerous research projects funded from the Greek Government and Industry as well as the European Commission (ESPRIT II-III-IV and 5th and 6th IST). He has served as General Chair and Program Chair for the International Workshop on Power and Timing Modelling, Optimisation, and Simulation (PATMOS). He received an award from INTEL and IBM for the project results of LPGD #25256 (ESPRIT IV). He is a member of the IEEE, the VLSI Systems and Applications Technical Committee of IEEE CAS and the ACM. Antonios Thanailakis was born in Greece on August 5, 1940. He received B.Sc. degrees in physics and electrical engineering from the University of Thessaloniki, Greece, 1964 and 1968, respectively, and the Msc. and Ph.D. Degrees in electrical engineering and electronics from UMIST, Manchester, U.K. in 1968 and 1971, respectively. He has been a Professor of Microelectronics in Dept. of Electrical and Computer Eng., Democritus Univ. of Thrace, Xanthi, Greece, since 1977. He has been active in electronic device and VLSI system design research since 1968. His current research activities include microelectronic devices and VLSI systems design. He has published a great number of scientific and technical papers, as well as five textbooks. He was leader for carrying out research and development projects funded by Greece, EU, or other organizations on various topics of Microlectronics and VLSI Systems Design (e.g. NATO, ESPRIT, ACTS, STRIDE).     

Bulk and microscopic properties of copolymer networks in mixed aqueous solvents

Amphiphilic films and hydrogels have been prepared from ethanol/water solutions containing a hydrocarbon-grafted water-soluble cellulose ether. These materials are characterized by dispersed hydrophobic microdomains which form spontaneously in the solvent due to the inherent incompatibility of the side chains with water. At low applied shear stress, the microdomains behave as temporary linkages of finite lifetimes, imparting viscoelastic properties to the networks. The molecular weight between microdomains was found to be independent of the volume fraction of polymer in the gel, and the number of linkages per backbone ranges from 22.8 ± 1.3 to 26.2 ± 1.5 over the frequency range 30–50 rad/s. The behavior of the solutions and gels was characterized using fluorescence and dynamic rheological measurements. It was demonstrated that the microdomains are capable of sequestering water-insoluble solutes. © 1992 John Wiley & Sons, Inc.     

Elastic constants of lead-bismuth alloys

A study of ultrasonic velocities and internal friction has been carried out in Pb-Bi alloys in the concentration range of 0 to 49.5 atomic % Bi using the composite oscillator technique. From the velocity and density data a set of elastic constants namely, Young’s modulus, rigidity modulus, bulk modulus and Poisson’s ratio are estimated. The results are interpreted in terms of the phase changes occurring in the alloy system. Internal friction is found to be more sensitive than the elastic constants to the phase changes.     

The Effect of Temperature on Lattice Mechanical Properties of Noble and Transition Metals

A simple pseudopotential model is used for the calculation of the temperature dependence of lattice mechanical properties which also depend on the phonon density of states such as lattice heat capacity C _V , Debye temperature _D, harmonic contribution to free energy, thermal pressure, isothermal bulk modulus corrected to the fourth order, volume thermal expansion coefficient , Debye-Waller factor, mean-square displacement, Debye-Waller temperature parameter, and X-ray characteristic temperature _M of Cu, Ag, Au, Ni, Pd, Pt, Rh, and Ir. The contribution of d-like electrons is taken into account by introducing repulsive short-range Born-Mayer-like term. Very recently proposed screening function due to Sarkar et al. has been used to obtain the screened form factor. The theoretical results are compared with experimental findings wherever possible. A good agreement between theoretical investigations and experimental findings show the ability of our model potential to reproduce wide class of properties in noble and transition metals.