Since a logic circuit often has too many paths to test delay of all paths, it is necessary for path delay testing to limit the number of paths to be tested. The paths to be tested should have large delay because such paths more likely cause a fault. Additionally, a test set for the paths are required to detect other models of faults as many as possible. In this paper, we investigate two typical criteria of path selection for path delay testing. From our experiments, we observe that test patterns for the longest paths cannot cover many local delay defects such as transition faults.

As the CMOS technology enters the very deep submicron era, inter-wire coupling capacitance becomes the dominant part of load capacitance. The coupling effects have brought new challenges to routing algorithms on both delay estimation and optimization. In this paper, we propose a timing-driven global routing algorithm with consideration of coupling effects. Our two-phase algorithm based on timing-relax method includes a heuristic Steiner tree algorithm to guarantee the timing performance of the initial solution and an optimization algorithm based on coupling-effect-transference. Experimental results are given to demonstrate the efficiency and accuracy of the algorithm.

In this paper, we deal with c-secure codes in a fingerprinting scheme, which encode user ID to be embedded into the contents. If a pirate copy appears, c-secure codes allow the owner of the contents to trace the source of the illegal redistribution under collusion attacks. However, when dealing in practical applications, most past proposed codes are failed to obtain a good efficiency, i.e. their codeword length are too large to be embedded into digital contents. In this paper, we propose a construction method of c-secure CRT codes based on polynomials over finite fields and it is shown that the codeword length in our construction is shorter than that of Muratani's scheme. We compare the codeword length of our construction and that of Muratani's scheme by numerical experiments and present some theoretical results which supports the results obtained by numerical experiments. As a result, we show that our construction is especially efficient in respect to a large size of any coalition c. Furthermore, we discuss the influence of the random error on the traceability and formally define the Weak IDs in respect to our construction.

Because most link-state routing protocols, such as OSPF and IS-IS, calculate routes using the Dijkstra algorithm, which poses scalability problems, implementors often introduce an artificial delay to reduce the number of route calculations. Although this delay directly affects IP packet forwarding, it can be acceptable when the network topology does not change often. However, when the topology of a network changes frequently, this delay can lead to a complete loss of IP reachability for the affected network prefixes during the unstable period. In this paper, we propose the Cached Shortest-path Tree (CST) approach, which speeds up intra-domain routing convergence without extra execution of the Dijkstra algorithm, even if the routing for a network is quite unstable. The basic idea of CST is to cache shortest-path trees (SPTs) of network topologies that appear frequently, and use these SPTs to instantly generate a routing table when the topology after a change matches one in the caches. CST depends on a characteristic that we found from an investigation of routing instability conducted on the WIDE Internet in Japan. That is, under unstable routing conditions, both frequently changing Link State Advertisements (LSAs) and their instances tend to be limited. At the end of this paper, we show CST's effectiveness by a trace-driven simulation.

Recently, millimeter-wave energy has attracted much attention as a new and novel energy source for materials processing. In the present paper, several unique features of millimeter-wave heating in materials processing are reviewed briefly and development of materials processing machines by mm-wave radiation is also described. In the application of mm-wave heating, sintering of high quality alumina ceramics having a high bending strength of about 800 MPa are first demonstrated and followed by preparation of aluminum nitride with a high thermal conductivity over 200 W/(mK) at a sintering temperature lower by 473-573 K than the conventional method, by which this processing can be expected to be one of the environment-conscious energy saving processes. A newly developed post-annealing process with mm-wave radiation is described, in which crystallization of amorphous perovskite oxide films prepared by plasma sputtering was attained at temperatures lower than that by the conventional heating and the dielectric constant of post-annealed SrTiO3 (STO) films by mm-wave radiation were drastically improved.

We propose a new protocol, Clustered Group Multicast (CGM), for multicasting in ad-hoc mobile networks. In CGM, there is a set of forwarding nodes (called multicast backbone) which are responsible for forwarding multicast datagrams. Unlike the multicasting protocols in wired networks (e.g., Internet) which construct and maintain a shortest path tree for every multicast {source, group} pair, CGM is a mesh-based multicasting protocol in which the connectivity among the nodes in the backbone is of no longer importance. Thus, there is no tree maintenance overhead, but there are more connectivity than trees and yet it can prevent long-term or permanent routing loops from occurring. A key feature of CGM is the use of the advertising agent to reduce advertising traffic to the system. An advertising agent acts as both a server and a client for the purpose of advertising join requests on behalf of its local clients. Because in CGM multicast traffic is only allowed to be delivered over the backbone, CGM restricts the amount of hosts participating in the backbone to decrease the impact of multicast traffic to the system. From the simulation results, the multicast group management traffic and multicast datagram traffic are much less than the other protocols. This is particularly important for wireless networks which lacks bandwidth.

A negative thermal expansion ceramic substrate and an athermal fiber Bragg grating component with the substrate were subjected to reliability tests. We confirmed that the component has adequate durability for use as optical filters in the WDM system, under test conditions of damp heat, low temperature, mechanical shock and vibration. (50 words)

We consider the routing and wavelength assignment (RWA) problem for large-scale WDM optical networks where each transmission request is served by an all-optical lightpath without wavelength conversion. Two heuristic RWA algorithms are proposed in order to minimize the number of wavelengths required for a given set of connection requests. The proposed algorithms are evaluated and compared with the existing algorithms for two realistic networks constructed based on the locations of major cities in Ibaraki Prefecture and those in Kanto District in Japan.

This paper is devoted to the modelling of microwave heating applicators using time domain vector finite elements. To reduce the discretisation error due to the dielectric losses of the materials analyzed, first and second order interpolatory and non-interpolatory vector finite element bases are studied. The modes of a resonant applicator used for microwave heating are numerically computed and compared with analytical solutions. The movement of a dielectric load in 45-degree intervals in a multimode applicator is numerically simulated and the results compared experimentally through measuring the return loss using a network analyzer. This paper reveals the relative merits of first and second order bases and shows the effectiveness of finite elements for simulating microwave heating processes.

Cluster systems are getting widely used because of good performance / cost ratio. However, their reliability has not been well discussed in practical environment so far. As the number of commodity components in a cluster system gets increased, it is indispensable to support reliability by system software. SCore cluster system software is a parallel programming environment for High Performance Computing (HPC). SCore provides checkpointing and rollback-recovery mechanism for high availability. In this paper, we analyze and evaluate the checkpointing and rollback-recovery mechanisms of SCore quantitively. The experimental results reveal that the required time for checkpointing scales very well in respect to the number of computing nodes. However, the required time is quite long due to the low effective network bandwidth. Based on the results, we modify SCore and successfully make checkpointing and recovery 1.8 2.8 times and 3.7 5.0 times faster respectively. This is very helpful for cluster systems to achieve high performance and high availability.

In ad hoc wireless networks, wireless terminals can autonomously construct and can maintain the network. They communicate with some neighbor terminals, exchange network information and determine routes for packets on the multi-hop wireless network. Flexible Radio Network (FRN), one of the ad hoc wireless network systems, adopts a proprietary protocol that provides a multiple routes management and a packet retransmission mechanism against packet transmission errors. This system is a commercial product that has been in use in a recent few years. In this paper, we first evaluate the performance through simulations for data-link protocol and routing protocol of the FRN to clarify its basic properties. Furthermore, we propose some techniques that enhance its performance and solve problems on the protocols. We show how they improve the system performance through simulations and analyses.

Reinforcement Learning (RL) is an efficient learning method for solving problems that learning agents have no knowledge about the environment a priori. Ant Colony System (ACS) provides an indirect communication method among cooperating agents, which is an efficient method for solving combinatorial optimization problems. Based on the cooperating method of the indirect communication in ACS and the update policy of reinforcement values in RL, this paper proposes the Q-ACS multiagent cooperating learning method that can be applied to both Markov Decision Processes (MDPs) and combinatorial optimization problems. The advantage of the Q-ACS method is for the learning agents to share episodes beneficial to the exploitation of the accumulated knowledge and utilize the learned reinforcement values efficiently. Further, taking the visited times into account, this paper proposes the T-ACS multiagent learning method. The merit of the T-ACS method is that the learning agents share better policies beneficial to the exploration during agent's learning processes. Meanwhile, considering the Q-ACS and the T-ACS as homogeneous multiagent learning methods, in the light of indirect media communication among heterogeneous multiagent, this paper presents a heterogeneous multiagent RL method, the D-ACS that composites the learning policy of the Q-ACS and the T-ACS, and takes different updating policies of reinforcement values. The agents in our methods are given a simply cooperating way exchanging information in the form of reinforcement values updated in the common model of all agents. Owning the advantages of exploring the unknown environment actively and exploiting learned knowledge effectively, the proposed methods are able to solve both problems with MDPs and combinatorial optimization problems effectively. The results of experiments on hunter game and traveling salesman problem demonstrate that our methods perform competitively with representative methods on each domain respectively.

Field-theoretical equivalent circuit models of a variety of coplanar waveguide (CPW) lumped-element discontinuities for two dominant modes are characterized by executing the short-open calibration (SOC) procedure in the fullwave method of moments (MoM). In our developed MoM platform, the impressed current sources with even or odd symmetry are introduced at the selected ports in order to separately excite the even and odd dominant modes, i.e., CPW- and CSL-mode. After the port network parameters are numerically derived using the Galerkin's technique, the two SOC standards are defined and evaluated in the self-consistent MoM to effectively de-embed and extract the core model parameters of a CPW circuit or discontinuity. After the validation is confirmed via comparison with the published data, extensive investigation is carried out to for the first time demonstrate the distinctive model properties of one-port CPW short- and open-end elements as well as two-port inductive and capacitive coupling elements with resorting to its two different dominant modes.

Fault-tolerant execution of a mobile agent is an important design issue to build a reliable mobile agent system. Several fault-tolerant schemes for a single agent system have been proposed, however, there has been little research result on the multi-agent system. For the cooperating mobile agents, fault-tolerant schemes should consider the inter-agent dependency as well as the mobility; and try to localize the effect of a failure. In this paper, we investigate properties of inter-agent dependency and agent mobility; and then characterize rollback propagation caused by the dependency and the mobility. We then suggest some schemes to localize rollback propagation.

The performance of a GMPLS switching architecture with or without the flush capability is studied. For this switching architecture, we propose a queueing model that includes the control plane, the switch buffer mechanism, and the flush mechanism. The flush capability is included to reduce the out-of-sequence problem due to dynamic path changes. The behavior of aggregated streams, the label-setup and release policies, and the mechanisms for efficient resource allocation are all covered. With the proposed model, one can select appropriate parameters for the label-setup policy and the label-release policy to match the traffic load and network environment. Key performance metrics, such as the label-setup rate, the switching ratio, the bandwidth utilization of the label switched path, the average delay, and the average packet loss rate, can all be evaluated via this mathematical model. Numerical results and simulations are used to verify the accuracy of the proposed queueing model. Furthermore, we adopt trace simulation to certify the applicability the proposed model. The trade-off among these performance metrics can be observed as well.

Making up an electromagnetic wave simulator based on the FEM is tried, which may run on some widely used platforms by use of Java and a single commercial tool. Since the codes and configuration files to be created for this simulator are common, one can construct the simulator running on the platforms at the same time. Using this simulator, the transmission properties of two- and three-dimensional waveguide discontinuities in optical and microwave waveguides are analyzed, the inverse problem in material constant measurement is solved, and the computed results are presented including plots of the electric field distribution.

The performance of a mobile ad hoc network (MANET) is related to the efficiency of the routing protocol in adapting to changes in the network topology and the link status. However, the use of many different mobility models without a unified quantitative "measure" of the mobility has made it very difficult to compare the results of independent performance studies of routing protocols. In this paper, a mobility measure for MANETs is proposed that is flexible and consistent. It is flexible because one can customize the definition of mobility using a remoteness function. It is consistent because it has a linear relationship with the rate at which links are established or broken for a wide range of network scenarios. This consistency is the strength of the proposed mobility measure because the mobility measure reliably represents the link change rate regardless of network scenarios.

A simple non-destructive depth estimation method for a crack on a metal surface has been proposed. This method is based on our finding that the electromagnetic back scattering from a narrow trough (crack model) on the ground plane causes periodical nulls (dips) as the frequency changes, and the first dip occurs when the depth of the crack becomes nearly one half of the incident wavelength. Dependencies of the crack's aperture and the incident angle have also been studied from rigorous and numerical analyses, and considered as our depth estimation parameters. A simple estimation formula for a crack depth has been derived from these studies. Test measurement has been made to check the accuracy of our estimation formula. Time domain gating process is utilized for isolating the crack scattering spectra buried in the measured frequency RCS data. Tested crack types are a narrow rectangular, a tapered, and a stair approximated crack shapes. It is found that the depth of these cracks can be measured within 3 percent error by our estimation method.

We developed a process to fabricate optical functions such as, lens, prism, or diffuser directly on to a glass substrate. Processes include precision mastering by diamond cutting, and multi-layer photopolymer (2P) molding process to realize flat surface and integration of multiple functions with a good alignment within few micrometers.

This letter proposes a novel technique for evaluating the longitudinal distribution of the Raman gain characteristics in optical fibers connected to a reference optical fiber with a known Raman gain efficiency. This technique can evaluate the Raman gain efficiency in test fibers using a simplified experimental setup. We performed experiments on various test fibers and confirmed that their Raman gain efficiency can be obtained easily and accurately by employing a reference fiber.