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。     

Optimal Layout of Sewer Systems: A Deterministic versus a Stochastic Model

The optimization of a new or partially existing urban drainage system may be modeled as a subproblems sequence of layout and optimal design within the discrete search space. The design optimization, incorporating the optimal selection of the pumping stations, intermediate manholes, pipe sections, and installation depths, for a general system fixed layout in plan, is a high level sequential decision problem which may be efficiently solved deterministically through a multilevel dynamic programming model. The optimal general layout may be selected in a deterministic way by means of a simple economical comparison of all plan solutions having optimized designs, for small to medium sized systems (if the specific restrictions of the applications are appropriately exploited) in practicable computer time. For larger dimension networks, where it is clearly impossible to achieve plan optimization with full enumeration (which is a NP complete), stochastic search models can be used. For the subproblem layout, an effective enumeration model is presented; the results of a stochastic model proposed previously, using simulated annealing for an application example, are compared and discussed in detail.     

Modeling and querying moving objects in networks

Moving objects databases have become an important research issue in recent years. For modeling and querying moving objects, there exists a comprehensive framework of abstract data types to describe objects moving freely in the 2D plane, providing data types such as moving point or moving region. However, in many applications people or vehicles move along transportation networks. It makes a lot of sense to model the network explicitly and to describe movements relative to the network rather than unconstrained space, because then it is much easier to formulate in queries relationships between moving objects and the network. Moreover, such models can be better supported in indexing and query processing. In this paper, we extend the ADT approach by modeling networks explicitly and providing data types for static and moving network positions and regions. In a highway network, example entities corresponding to these data types are motels, construction areas, cars, and traffic jams. The network model is not too simplistic; it allows one to distinguish simple roads and divided highways and to describe the possible traversals of junctions precisely. The new types and operations are integrated seamlessly into the ADT framework to achieve a relatively simple, consistent and powerful overall model and query language for constrained and unconstrained movement.     

A Universal Accepting Hybrid Network of Evolutionary Processors

We propose a construction of an accepting hybrid network of evolutionary processors (AHNEP) which behaves as a universal device in the class of all these devices. We first construct a Turing machine which can simulate any AHNEP and then an AHNEP which simulates the Turing machine. We think that this approach can be applied to other bio-inspired computing models which are computationally complete.     

On some operations on strings suggested by gene assembly in ciliates

We define three operations on strings and languages suggested by the process of gene assembly in hypotrichous ciliates. This process is considered to be a prine example of DNA computing in vivo. This paper is devoted to some computational aspects of these operations from a formal language point of view. The closure of the classes of regular and context-free languages under these operations is settled. Then, we consider theld-macronuclear language of a given languageL, which consists of allld-macronuclear strings obtained from the strings ofL by iteratively applying the loop-direct repeat-excision. Finally, we discuss some open problems and further directions of research. Rudolf Freund: He received his master and doctor degree in computer science from the Vienna University of Technology, Austria, in 1980 and 1982, respectively. In 1986, he received his master degree in mathematics and physics from the University Vienna, Austria. In 1988 he joined the Vienna University of Technology in Austria, where he became an Associate Professor in September 1995. He has given various lectures in theoretical computer science, especially on formal languages and automata. His research interests include array and graph grammars, regulated rewritung, infinite words, syntactic pattern recognition, neural networks, and especially models and systems for biological computing. In these fields he is author of more than sixty scientific papers. Carlos Martín-Vide: He is Professor and Head of the Research Group on Mathematical Linguistics at Rovira i Virgili University, Tarragona, Spain. His specialities are formal language theory and mathematical linguistics. His last volume edited is Where Mathematics, Computer Science, Linguistics and Biology Meet (Kluwer, 2001, with V. Mitrana). He published 150 papers in conference proceedings and journals such as: Acta Informatica, BioSystems. Computational Linguistics, Computers and Artificial Intelligence, Information Processing Letters, Information Sciences, International Journal of Computer Mathematics, New Generation Computing, Publicationes Mathematicae Debrecen, and Theoretical Computer Science. He is the editor-in-chief of the journal Grammars (Kluwer), and the chairman of the 1st International PhD School in Formal Languages and Applications (2001–2003). Victor Mitrana, Ph.D.: He is Professor of Computer Science at the Faculty of Mathematics, University of Bucharest. He received his MSc and PhD from the University of Bucharest in 1986 and 1993, respectively. In 1999 he was awarded with the “Gheorghe Lazar” Prize for Mathematics of the Romanian Academy. His research interests include: formal language theory and applications, combinatorics on words, computational models inspired from biology, mathematical linguistics. In these areas, he published three books, more than 100 papers, and edited two books. He is an associate editor of “The Korean Journal of Computational and Applied Mathematics” and an editor of “Journal of Universal Computer Science”.     

Enthalpy of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys

The partial (Δ and the integral (ΔH) enthalpies of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys have been determined by high-temperature isoperibolic calorimetry at 1565 ± 5 K. The heat capacity (C _p) of liquid Ni₂₆Zr₇₄ has been measured by adiabatic calorimetry (C _p=53.5±2.2 J mol⁻¹ K⁻¹ at 1261±15 K). The integral enthalpy of mixing changes with composition from a small positive (Cu-Ni, ΔH (x _Ni=0.50, T=1473 to 1750 K)=2.9 kJ mol⁻¹) to a moderate negative (Cu-Zr; ΔH(x _Zr=0.46, T=1485 K)=−16.2 kJ mol⁻¹) and a high negative value (Ni-Zr; ΔH(x _Zr=0.37, T=1565 K)=−45.8 kJ mol⁻¹). Regression analysis of new data, together with the literature data for liquid Ni-Zr alloys, results in the following relationships in kJ mol⁻¹ (standard states: Cu (1), Ni (1), and Zr (1)):for Ni-Zr (1281≤T≤2270 K),

Analysis of the ∈-Expansion in Turbulence Theory: Approximate Renormalization Group for Diffusion of a Passive Scalar in a Random Velocity Field

The validity of the -expansion in the turbulence problem is discussed using the example of diffusion of a passive scalar in a random velocity field. A generalization of Wilson's rule for calculating a diagram of arbitrary order is introduced. The resulting perturbation series, while having zero radius of convergence, is summed exactly yielding amplitudes which differ from those obtained to lowest order in the -expansion by only a few percent. The properties of the expansion are analyzed in detail and it is shown that various subsets of diagrams, while differing by an infinite number of terms, give close results in the vicinity of the fixed point. This indicates nontrivial compensation of high-order interactions in turbulence. The irrelevance of high-order couplings is demonstrated for arbitrary values of . The quality the approximation is tested by comparison with numerical experiments on diffusion of a passive scalar in a band-limited random velocity field in the limit of infinite Peclet number.     

Analysis of emptiness (lacunarity) as a measure of the degree of space filling and of the internal structure of a set

The study presents a comparative evaluation of emptiness (lacunarity) in model structures with different types of inhomogeneity of dispersed particle distributions. The research on emptiness (lacunarity) as a measure of the degree of space filling and, at the same time, of the internal characterization of a set has been based on the optimal covering and gliding-box methods.