We propose a new associative memory named Multi-Winner Associative Memory (MWAM) and study its bidirectional association properties in this paper. The proposed MWAM has two processes for pattern pairs storage: storage process and recall process. For the storage process, the proposed MWAM can represent a half of pattern pair in the distributed representation layer and can store the correspondence of pattern and its representation using the upward weights. In addition, the MWAM can store the correspondence of the distributed representation and the other half of pattern pair in the downward weights. For the recall process, the MWAM can recall information bidirectionally: a half of the stored pattern pair can be recalled by receiving the other half in the input-output layer for any stored pattern pairs.

The concept of controlled resource sharing and dynamic quality of service (QoS) on the next generation Internet has attracted much attention recently. It is suggested that, by imposing real-time revision of shared resource allocated to individual media streams or data flows according to user/application QoS demand and resource availability, more balanced and efficient multimedia services can be provided. In this paper, we present an Adaptive Control Framework (ACF), which is developed for controlled resource sharing and dynamic QoS in real-time multimedia service. We discuss main elements of ACF including 1) Control schemes applicable in the framework, and 2) Control mechanisms used in ACF. It is clearly shown in this paper that, with control schemes and mechanisms incorporated in ACF and supportive algorithms and protocols for ACF applications on the Internet, more flexible service and better overall performance in terms of packet loss, latency, signal-noise ratio and re-synchronization delay, can be offered.

In this paper 2-10 GHz hybrid-distributed preamplifiers using two and three cascaded single stage distributed amplifiers are demonstrated. These amplifiers produce available power gains significantly higher than conventional distributed preamplifiers using the same number of active devices. Simulation results show the advantage of the proposed preamplifier over the conventional one. Measured results of the two realised configurations of preamplifiers using two and three cascaded single stage distributed amplifiers are presented. Each configuration shows that the available power gain can be increased by increasing interstage characteristic impedance of the cascaded single stage distributed amplifiers. The measured available power gain for two stages shows an improvement from 18 dB to 20 dB, and for three stages an improvement from 26 dB to 31 dB across the 2-10 GHz frequency band, as the inter-stage characteristic impedance is increased from low to high level. Input and output return losses better than -10 dB, and input-output isolation better than -55 dB at the beginning of the band and better than -45 dB at the end are achieved. This approach also provides a good measured noise figure performance of an average of 4 dB across the 2-10 GHz frequency band for both two and three cascaded stages. The group delay of both cascaded amplifiers are measured. Its flat performance proves the viability of this approach which is suitable for digital optical communication and pulse applications.

A distributed computing system consists of processing elements, communication links, memory units, data files, and programs. These resources are interconnected via a communication network and controlled by a distributed operating system. The distributed program reliability (DPR) in a distributed computing system is the probability that a program which runs on multiple processing elements and needs to retrieve data files from other processing elements will be executed successfully. This reliability varies according to 1) the topology of the distributed computing system, 2) the reliability of the communication edges, 3) the data files and programs distribution among processing elements, and 4) the data files required to execute a program. In this paper, we show that computing the distributed program reliability on a star distributed computing system is #P-complete. A polynomially solvable case is developed for computing the distributed program reliability when some additional file distribution is restricted on the star topology. We also propose a polynomial time algorithm for computing the distributed program reliability with approximate solutions when the star topology has no the additional file distribution.

This paper proposes a new distributed connection establishment scheme involving several competing network providers in a multimedia telecommunications environment. This connection establishment scheme, which is based on the concept of open competitive bidding, enables mutual selection by users and network providers. By employing this proposed scheme, both network providers and users can pursue their own objectives, according to their own bidding and awarding strategies. In this paper, a simple bidding strategy for network providers is presented, and the effectiveness of this strategy is evaluated by means of computer simulation. It is shown that each network provider can improve its profit by adopting this strategy. In this paper, an example of utility functions for users is presented, and the effectiveness of the mechanism with which users can select a network provider is also evaluated by means of computer simulation. Each user can improve his/her utility by selecting an appropriate network provider based on this utility function.

In a distributed network management environment, a NMS (Network Management Station) interacts with several agents in different sub-networks. In the network fault management context, the NMS detects symptoms that indicate some abnormality e. g. a surge in ICMP traffic, which may be caused by some network malfunction or misuse. The occurrence of a symptom is an event. Large number of events may be detected by an NMS. The sheer number of these events makes it difficult, if not impossible, for an NMS to diagnose these events. Generally, a fault may have a cascading effect which may, in turn, give rise to a very large number of events. The sequence of events and their correlation play an important role in fault management and diagnosis. In the distributed environment of todays networks, the absence of any uniform time for reference makes this a challenging task. In the present network management framework of SNMP, a Manager maintains a notion of the clock of the agent it interacts with. But this mechanism is inadequate to determine the sequence of events and their correlation, more so, in a distributed environment which may involve several managers. In this paper we propose a mechanism for ordering and correlating events detected in large-scale network which is managed in a distributed manner within the SNMP framework. Our algorithm uses the concept of a Network Management Clock (NMC). The NMC is a virtual clock maintained by a manager based on sysUpTime readings from each SNMP agent. In this paper, the algorithm, its implementation and evaluation will be discussed.

This paper discusses the implementation and cost- and performance- evaluations of a distributed processing network, called DONA-α, which is one of the possible physical networks mainly implementing connection-oriented public switched network functions corresponding to OSI layers 1 to 3. The first feature of the DONA-α network is that it separates a switching subsystem and a control subsystem of a conventional switching system and independently allocates them over distributed nodes as a switching node and a control node. Each DONA-α switching node is given a much smaller switching capacity than the switching subsystem of the conventional switching system and is located near subscribers. In contrast, each DONA-α control node has much higher performance than the control subsystem of the conventional switching system. This allows a large number of switching nodes to share the same control node, which controls their connection setups. This separation provides the network with greater flexibility and allows more effective utilization of network resources, such as control processors, switching fabrics, and transmission links, than ever before. The second feature of DONA-α is that it provides a network with network-wide distribution transparency. This allows network resources including software such as databases and application programs to be shared and therefore to be utilized in the network more easily and more efficiently. The results of a network performance simulation and cost calculation confirm the viability of the DONA-α network.

To design and develop user-oriented, flexible and distributed applications which can deal with various users' requirements, new technologies to manage, control and utilize the services of communication networks have to be provided. In this paper, the current challenges faced by large-scale distributed applications are discussed and a framework for the next generation network operation and management is presented on the basis of agent-based computing technologies. Examples of flexible distributed applications are presented to clarify the role of application-centric flexible network operation and management.

This paper discusses the generalized mutual exclusion problem defined by H. Kakugawa and M. Yamashita. A set of processes shares a set of resources of an identical type. Each resource must be accessed by at most one process at any time. Each process may have different accessible resources. If two processes have no common accessible resource, it is reasonable to ensure a condition in resource allocation, which is called allocation independence in this paper, i. e. , resource allocation to those processes must be performed without any interference. In this paper, we define a new structure, sharing structure coterie. By using a sharing structure coterie, the resource allocation algorithm proposed by H. Kakugawa and M. Yamashita ensures the above condition. We show a necessary and sufficient condition of the existence of a sharing structure coterie. The decision of the existence of a sharing structure coterie for an arbitrary distributed system is NP-complete. Furthermore, we show a resource allocation algorithm which guarantees the above requirement for distributed systems whose sharing structure coteries do not exist or are difficult to obtain.

This paper proposes a traffic-adaptive dynamic routing method, which we have named RAG, for connectionless packet networks. Conventional traffic control methods discard the packets which cause congestion. Furthermore, conventional routing methods propagate control messages all over the network for gathering global topology information, and this causes more congestion. In contrast, RAG estimates traffic conditions all over a network without any communication between nodes and makes the best use of free links so that packets make detours to avoid congestive sites. RAG adopts distributed control based on game theory (non-communication, non-zero-sum, two-person). With RAG, nodes play a packet-forwarding game without any communication with each other, and each node controls ordering and routing of the forwarding packets based on the node's individual payoff table which is dynamically reconstructed by observation of surrounding nodes. Nodes cooperate with each other, except for punishment for disloyalty. Repetition of these local operations in nodes aims at the emergence of the gradual network-global traffic balancing. The results of experiments in comparison with the conventional shortest path first (SPF) routing method show that the throughput is about 1.58 times higher with the new method.

Optical frontend and distributed amplifier IC modules, both containing GaAs heterojunction-bipolar-transistors (HBT), have been developed for 40 Gb/s optical receiver. To achieve high-speed operations, the elements in the modules including the IC and signal lines, were designed to achieve a wider bandwidth with lower electrical reflection. The influence of a bonding-wire inductance was taken into particular account in optimizing the parameters of the ICs. The optical frontend, consisting of a waveguide pin-photodiode and an HBT preamplifier IC, exhibits a transimpedance gain of 43 dBΩ and a bandwidth of 31 GHz. The distributed amplifier IC module achieves a gain of 9 dB and a bandwidth of 39 GHz. A 40-Gb/s optical receiver constructed with these modules exhibited a high receiver sensitivity of -28. 2 dBm for a 40-Gb/s optical return-to-zero signal.

The Conjugate Residual method, one of the iterative methods for solving linear systems, is applied to the problems with a dense coefficient matrix on distributed memory parallel computers. Based on an assumption on the computation and communication times of the proposed algorithm for parallel computers, it is shown that the optimal number of processing elements is proportional to the problem size N. The validity of the prediction is confirmed through numerical experiments on Hitachi SR2201.

A novel method is proposed to calculate the distributed coupling of dual-modes in a circular resonator. New theoretical expressions are devised to accumulate the infinitesimal coupling between orthogonal modes and their validity is justified by the FD-TD analysis and experiments. The distributed coupling concept of a circular disk resonator is applied to a square disk resonator to calculate its resonant frequency. We have fabricated two types of low-profile dual-mode square dielectric disk resonator BPF, using high dielectric constant material (εr = 93) having a dimension of 5 mm 5 mm 1 mm. The filter characteristics are explained by the transmission line circuit model.

We propose two lockout-free (starvation-free) mutual exclusion algorithms for the asynchronous multi-writer/reader shared memory model. The first algorithm is a modification of the well-known tournament algorithm for the mutual exclusion problem. By the modification we can speed up the original algorithm. The running time of the modified algorithm from the entrance of the trying region to the entrance of the critical region is at most (n-1)c+O(nl), where n is the number of processes, l is an upper bound on the time between successive two steps of each process, and c is is an upper bound on the time that any user spends in the critical region. The second algorithm is a further modification of the first algorithm. It is designed so that some processes have an advantage of access to the resource over other processes.

For advanced data-oriented applications in distributed environments, effective information is frequently obtained by integrating or merging various autonomous information sources. There are many problems: how to search information sources, how to resolve their heterogeneity, how to merge or integrate target sources, how to represent information sources with a common protocol, and how to process queries. We have proposed a new language, QUIK, as an extension of a deductive object-oriented database (DOOD) language, QUIXOTE, and extend typical mediator systems. In this paper, we discuss various features of QUIK: programming capabilities as integrating an exchange model and mediator specifications, merging subsumption relations for maintaining consistency, searching alternative information sources by hypothesis generation, and identifying objects.

The advent of high-speed networks with quality of service guarantees, will enable the deployment of data-server distributed systems over wide-area networks. Most implementations of data-server systems have been over local area networks. Thus it is important, in this context, to study the performance of existing distributed data management protocols in the new networking environment, identify the performance bottlenecks and develop protocols that are capable of taking advantage of the high speed networking technology. In this paper, we examine and compare the scalability of the server-based two-phase locking protocol (s-2PL), and the group two-phase locking protocol (g-2PL). The s-2PL protocol is the most widely used concurrency control protocol, while the g-2PL protocol is an optimized version of the s-2PL protocol, tailored for high-speed wide-area network environments. The g-2PL protocol reduces the effect of the network latency by message grouping, client-end caching and data migration. Detailed simulation results indicate that g-2PL indeed scales better than s-2PL. For example, upto 28% improvement in response time is reported.

A method for expanding the channels of data acquisition unit used in distributed microcomputer data measure & control systems and a technique to call assembly routines by C Language are introduced in the paper. The method may increase the number of data acquisition points ten to hundreds times. So it may raise the price performance ratio of all distributed data measure & control system greatly. And the programming method may optimize program performance.

For the improvement of software quality and productivity, the author aims at realizing a software development environment to develop software through utilizing the merits of group work. Since networking is necessary for collaborative software development, he has developed a software distributed development environment for collaborative software development. In this environment, discussions about software design are held through a communication network, and the contents of discussions are recorded as software design decisions and decision rationale. One feature of this environment is that the contents of discussions can be recorded in on-line real time and reused without reconstructing the information recorded through this environment. This paper clarifies the essential conditions for actualizing this environment and proposes an information structure model for recording the contents of discussions that actualizes the above-mentioned feature. The effectiveness of the proposed model is proved through an example of its application to software design discussions.

There is increasing demand for corporate information systems that have a simple human interface and are easy to access via WWW browsers. This paper proposes WebBASE, which integrates the WWW and relational databases. Experimental evaluation shows that WebBASE offers superior performance compared to existing products. Field studies of actual WebBASE applications show that it can improve the productivity of software developers for intranet application development.

Array redistribution is required very often in programs on distributed memory parallel computers. It is essential to use efficient algorithms for redistribution, otherwise the performance of programs may degrade considerably. In this paper, we focus on automatic generation of communication routines for multi-dimensional redistribution. The principal advantage of this work is to gain the ability to handle redistribution between arbitrary source and destination processor sets and between arbitrary source and destination distribution schemes. We have implemented these algorithms using Parallelware communication library. Some experimental results show the efficiency and flexibility of our techniques compared to the other redistribution works.