A large body of research in the measurement of software complexity at code level has been conducted, but little effort has been made to measure the architectural-level complexity of a software system. In this paper, we propose some architectural-level metrics which are appropriate for evaluating the architectural attributes of a software system. The main feature of our approach is to assess the architectural-level complexity of a software system by analyzing its formal architectural specification, and therefore the process of metric computation can be automated completely.

Motion estimation is the key issue in video compressing. Several methods for motion estimation based on the center biased strategy and minimum mean square error trend searching have been proposed, such as TSS, FSS, UCBDS and MIBAS, but these methods yield poor estimates or find local minima. Many other methods predict the starting point for the estimation; such methods include PMEA, PSA and GPS: these can be fast but are inaccurate. This study addresses the causes of wrong estimates, local minima and incorrect predictions in the prior estimation methods. The Multiple Searching Trend (MST) is proposed to overcome the problems of ineffective searches and local minima, and the Adaptive Dilated Searching Field (ADSF) is described to prevent prediction from wrong location. Applying MST and ADSF to the listed estimating methods, such as UCBDS, a fast and accurate can be reached. For this this reason, the method is called CockTail Searching (CTS).

In this article, it is shown that Unified Complex Hadamard Transform (UCHT) can be derived from Walsh functions and through direct matrix operation. Unique properties of UCHT are analyzed. Recursive relations through Kronecker product can be applied to the basic matrices to obtain higher dimensions. These relations are the basis for the flow diagram of a constant-geometry iterative VLSI hardware architecture. New Normalized Complex Hadamard Transform (NCHT) matrices are introduced which are another class of complex Hadamard matrices. Relations of UCHT and NCHT with other discrete transforms are discussed.

At current interruption by electric contact, a repetition phenomenon of arc extinction and re-ignition is often observed before complete extinction of arc discharge, in some cases for a long time and in other cases for a short time. Occasionally, no re-ignition is observed. From a viewpoint of arc duration, the period of this repeating arc is also an important factor, if it is very long. However, the conventional explanation about the contact arc duration excludes this repeating arc phenomenon so that it fails to explain the reason and the duration of this phenomenon. For the purpose of investigating why this phenomenon occurs and how long it lasts, the arc extinction current and the arc re-ignition voltage have been measured for tungsten electrode, palladium electrode, copper electrode, and silver electrode. The circuit is, for simplicity, resistive with a capacitor source voltage and a fixed short arc gap of 0.5 mm. Taking newly into account the idea of unstable arc region by the measured results, the conventional explanation was improved. As a result, the reason and the duration of arc extinction and re-ignition phenomenon have become understandable. For simplification, the main description is based on the results by tungsten electrode. The results by other electrodes are summarized in appendix.

The AMR wideband speech codec was recently developed for high-quality wideband speech communications. Although it has an excellent performance due to expanded bandwidth of speech signal, it requires a huge amount of computation especially in codebook search. To solve this problem, this paper proposes an efficient codebook search method for AMR wideband codec. Starting from a poorly performing initial codevector, the proposed method enhances the performance of the codevector iteratively by exchanging the worst pulse in the codevector with a better one after evaluating the role of each pulse. Simulations show that the AMR wideband codec adopting the proposed codebook search method provides better performance with much less computational load than that using the standard method.

The vacuum arc root properties (temperature, current density, radius of an arc root, fraction of current density carried by electrons, evaporation rate etc.) of graphite and copper are calculated with the cathode-fall voltage as parameter and the arc root properties of graphite are compared with that of copper. Especially, there is big difference between the evaporation rate of graphite and that of copper. This reason is thought that the thermal conductivity of graphite is low and its evaporating temperature is high.

The three major failures of electrical contacts for automotive relay applications are: contact welding (or contact sticking), high contact resistance and severe contact erosion due to switching arcing. With the demand of high power and multiple functions of automotive vehicles, the switching current has be dramatically increased, it results in higher failing rate, in particular for contact welding. On the other hand, the miniaturization of electromechanical relays has lead to the reduction of mechanical spring force. This not only results in the earlier contact welding but also makes the relay more susceptible to the contact resistance and arc erosion failures. This paper is a review of most recent studies on these three failure aspects. It describes the progress in the understanding of contact welding caused by short arcing and high contact resistance due to contamination of particles and films in relay manufacturing process and also it review the material transfer due to switching arcing. At the end, the brief considerations of electromechanical relays used in 42 volts have also been given.

Automotive fuel pumps are driven by small DC motor. Commutation is carried out in gasoline, and arc voltage and duration are different from that in air. Our laboratory have analyzed commutation phenomenon in gasoline quantitatively and we have considered brush materials. To develop high power motor, we need to examine materials that are less arc abrasion and good sliding condition. In this research, we attend to characteristics of flat carbon commutator. As a result, it is possible to drive longer time, like established cylindrical copper commutator.

We propose a new electric contact device that greatly improves arc discharge characteristics. Electric contact functions are divided into an energizing operation and a switching operation. A capacitor is connected in series to a contact for switching contact. Using two conventional relay contacts, no arc operation is confirmed for a 42 V/3 A break operation. Contact resistances are measured over many operations, and the surfaces of electrodes are observed. A chip capacitor is arranged at one side of the contact electrodes of a twin relay, confirming the possibility of miniaturization.

The purpose of this study is to examine the impact of the opening speed on a breaking arc. The opening speeds are 10, 20 and 30 mm/s. The breaking arc is generated in a D.C. 42 V/10.5 A circuit, and the arc voltage, the arc current, the gap length and the arc spectrum intensity are measured. Arc temperature is calculated by using a Boltzmann plot. Even if the opening speed is changed, the arc temperature starts from a high temperature, and falls gradually to 4650-4750 K with time. Namely, the opening speed has no influence on the arc temperature.

A new scheme for evaluation of shapes of pips and craters formed by arc discharges on electrical contact surfaces is proposed. Measuring a height of a pip or a depth of a crater as well as an average diameter thereof with a scanning laser microscope and then putting a plot having the measured values as its vertical and horizontal coordinates enable us to numerically and briefly evaluate shapes of those pips and craters on arc-damaged contact surfaces. Some exemplary results obtained by this evaluation scheme are presented here.

In this letter, DAB system employing multiple antenna scheme is considered for high capacity transmission. In the MIMO-DAB system, the transmission rate is augmented efficiently by increasing the number of antennas, and thus the multi-channel estimation process is required. So, this letter proposes a new phase reference symbol structure which can be adapted to the multi-channel estimation, and investigates the channel estimation performance based on the semi-blind processing using the time-domain windowing. Simulation results have been shown that the MIMO-DAB system with multi-antennas can achieve the high-rate transmission for multimedia broadcasting.

Breaking arcs occurring between Ag or Cu electrical contact pairs in DC 56 V/7 A resistive circuit are observed with a high-speed camera (1000 frames/s). As a result, the increase of brightness of the arc-emitted light synchronizes with the increase of arc current in the latter half of arc duration. For the case of Ag contacts, the brightness increases in entire region of the breaking arc with sudden increase of the arc current. On the other hand, the increase of the intensity for Cu contacts occurs in not only entire discharge region but also anode spot region significantly.

To measure the arc motion in interruption process of low voltage molded case circuit breakers (MCCBs) more precisely, a set of novel 2-D optical fiber system is developed. To improve the spatial resolution of optical fibers, lens with inhomogeneous dielectric is fixed on the top of each fiber. Furthermore, the full hardware control logic facilitates the real-time, synchronous and high-speed processing and breaks through the restricted bus operation frequency range and data stream capacity of microprocessor. The Publisher-Subscribe behavioral design pattern is applied to the software and the loosely coupled relationship between glyph and experimental data is once established, the graphic configuration can be implemented for simulation analysis, and the flexibility and applicability of the whole system are obviously improved. It demonstrates that the system provides a better research technique especially for new generation MCCB with gas driven arc.

In this letter we suggest sets of features to classify genres of web documents. Web documents are different from textual documents in that they contain URL and HTML tags within the pages. We introduce the features specific to web documents, which are extracted from URL and HTML tags. Experimental results enable us to evaluate their characteristics and performances. On the basis of the experimental results, we implement a user interface of a web search engine that presents documents grouped by genres.

A large-scale packet-switch architecture for a tera bit/s system--which uses a combined-packet-distribution (CPD) method for a crossbar packet switch--was developed. This method eliminates the restriction on scheduling processing time by extending a switching data unit. The data unit is called a combined packet that consists of plural variable-length packets or their fragments. The combined packets are sequentially distributed among multiple crossbar switch planes and their sequence integrity is preserved. Distributive targets among the switch planes are selectable. As a result, when one or more switch planes are damaged, redundancy of the switch fabric is easily attained in a so-called "graceful degradation" manner. Moreover, this switch uses a novel algorithm called hierarchical priority scheduling. This algorithm enables fairness of scheduling by taking account of queuing state. The repetition required for priority scheduling is reduced by a novel hierarchical approach. The simulated performance of this algorithm shows that it performs better than the simple maximal matching method under both uniform and non-uniform traffic.

This letter proposes a low-power tournament branch predictor, in which the number of accesses to the branch predictors (local predictor or global predictor) is reduced. Analysis results with Samsung Memory Compiler show that the proposed branch predictor reduces the power consumption by 24-45%, compared to the conventional tournament branch predictor, not requiring any additional storage arrays, not incurring any additional delay and never harming accuracy.

This paper proposes a new type of relationship between layers in layered architecture and shows how to concretize the relationship between layers into design constraints. The meaning of layer relationship is explained with examples from design patterns and Microsoft COM. In addition, a prototype tool to check conformance is implemented and the architecture document of an open-source software project is checked against the actual architecture extracted from source code developed by many international developers. As a result of checking, parts that do not conform to the architecture document are investigated and it is pointed out that their modifications should be controlled with caution.

Decentralized and unstructured peer-to-peer (P2P) networks such as Gnutella are attractive for large-scale information retrieval and search systems because of their scalability, fault-tolerance, and self-organizing nature. Because of this decentralized architecture, however, traditional P2P keyword search systems are difficult to globally share useful semantic knowledge among nodes. As a result, traditional P2P keyword search systems cannot support semantic search (support only naive text-match search). In this paper, we describe a design of the semantic P2P keyword search system. We exploit the semantics of correlation among keywords rather than synonym. The key mechanism is query expansion, where a received query is expanded based on keyword relationships. Keyword relationships are improved through search and retrieval processes and each relationship is shared among nodes holding similar data items. This semantic P2P search system has two main advantages. First, expanding search results through query expansion increases the possibility of locating desired data items which would not be found by traditional P2P search systems due to the keywords' textual mismatch. Second, keyword relationships originally introduced for query expansion, can be used for result ranking. Our main challenges are 1) managing keyword relationships in a fully decentralized manner and 2) maintaining the quality of search results, while suppressing result implosion. We also describe the prototype implementation and evaluation of the semantic P2P search system.

In this paper, two efficient VLSI architectures for biorthogonal wavelet transform are proposed. One is constructed by the filter bank implementation and another is constructed by the lifting scheme. In the filter bank implementation, due to the symmetric property of biorthogonal wavelet transform, the proposed architecture uses fewer multipliers than the orthogonal wavelet transform. Besides, the polyphase decomposition is adopted to speed up the processing by a factor of 2. In the lifting scheme implementation, the pipeline-scheduling technique is employed to optimize the architecture. Both two architectures are with advantages of lower implementation complexity and higher throughput rate. Moreover, they can also be applied to realize the inverse DWT efficiently. Based on the above properties, the two architectures can be applied to time-critical image compressions, such as JPEG2000. Finally, the architecture constructed by the lifting scheme is implemented into a single chip on 0.35 µm 1P4M CMOS technology, and its area and working performance are 5.005 5.005 mm2 and 50 MHz, respectively.