Connectionless data from existing network applications compose a large portion of the workload during an early ATM deployment, and are likely to make up an important portion of ATM's workload even in the long term. For providing a connectionless service over the ATM network, we compare two approaches; an indirect and a direct approaches, which are adopted by International Telecommunication Union-Telecommunication (ITU-T) as generic approaches. Our main subject of this paper is to compare network costs of two approaches by taking into account several cost factors such as transmission links, buffers, and connectionless servers in the case of the direct approach. Since the cost of the direct approach heavily depends on the configuration of a virtual connectionless overlay network, we propose a new heuristic algorithm to construct an effective connectionless overlay network topology. The proposed algorithm determines an optimal number of connectionless servers and their locations to minimize the network cost while satisfying QoS requirements such as maximum delay time and packet loss probability. Through numerical examples, we compare the indirect and direct approaches, the latter of which is constructed by means of our proposed algorithm.

This paper describes the new write/erase operation methods in order to improve the read disturb characteristics for Flash EEPROM cells which are written by channel hot electron injection and erased by F-N tunneling emission from the floating gate to the substrate. The new operation methods is either applying a reverse polarity pulse after each erase pulse or applying a series of shorter erase pulses instead of a long single erase pulse. It is confirmed that by using the above operation methods, the leakage current can be suppressed, and then the read disturb life time after 105 cycles write/erase operation is more than 10 times longer in comparison with the conventional method. This memory cell by using the proposed write/erase operation method has superior potential for application to 256 Mbit Flash memories as beyond.

Distributed multimedia applications are often sensitive to the Quality of Service (QoS) provided by the communication network. They usually require guaranteed QoS service, so that real-time communication is possible. However, searching a route with multiple QoS constraints is known to be a NP-complete problem. In this paper, we propose a new simple and efficient distributed QoS routing algorithm, called "DQoSR," for supporting real-time communication in high-speed networks. It searches a route that could guarantee bandwidth, delay, and delay jitter requirements. Routing decision is based only on the modified cost, hop and delay vectors stored in the routing table at each node and its directly connected neighbors. Moreover, DQoSR is proved to construct loop-free routes. Its worst case message complexity is O(|V|2), where |V| is the number of nodes in the network. Thus DQoSR is fast and scales well to large networks. Finally, extensive simulations show that average rate of establishing successful connection of DQoSR is very near to optimum (the difference is less than 0.4%).

In this paper we propose a comprehensive approach to physical design based on the constraint paradigm. Bounds on the most critical circuit parasitics are automatically generated to help designers and/or physical design tools meet a set of high-level specifications. The constraint generation engine is based on constrained optimization, where various parasitic effects on interconnect and devices are accounted for and dealt with in different manners according to their statistical behavior and their effect on performance.

The electric field intensity of the THz radiation from YBCO thin films excited by ultrashort laser pulses has been enhanced by a factor of 3 using a-axis oriented films instead of c-axis oriented ones used previously under the same excitation conditions. This corresponds to the enhancement of a factor of 10 for the radiation power. From the transmittance measurements of the millimeter wave for a-and c-axis oriented films, the origin of the enhancement is attributed to the increased fraction of the THz electromagnetic wave power transmitted from the YBCO film to free space. This result indicates that the utilization of the anisotropic properties of high-Tc superconductors is effective to enhance the radiation power.

In layout design of transport-processing FPGAs, it is required that not only routing congestion is kept small but also circuits implemented on them operate with higher operation frequency. This paper extends the proposed simultaneous placement and global routing algorithm for transport-processing FPGAs whose objective is to minimize routing congestion and proposes a new algorithm in which the length of each critical signal path (path length) is limited within a specified upper bound imposed on it (path length constraint). The algorithm is based on hierarchical bipartitioning of layout regions and LUT (Look Up Table) sets to be placed. In each bipartitioning, the algorithm first searches the paths with tighter path length constraints by estimating their path lengths. Second the algorithm proceeds the bipartitioning so that the path lengths of critical paths can be reduced. The algorithm is applied to transport-processing circuits and compared with conventional approaches. The results demonstrate that the algorithm satisfies the path length constraints for 11 out of 13 circuits, though it increases routing congestion by an average of 20%. After detailed routing, it achieves 100% routing for all the circuits and decreases a circuit delay by an average of 23%.

Logic operations in principle have been demonstrated based on the planar high-Tc Superconducting QUantum Interference Device (SQUID). Two kinds of logic gates were produced by using the focused ion beam (FIB) superconducting weak links fabricated in NdBa2Cu3O7-δ (NBCO) thin films. Logic gates investigated in this paper are (1) an rf-SQUID based logic gate which utilizes threshold characteristics, and (2) a dc-SQUID based logic gate which is an elementary gate of RSFQ circuits. Elementary logic operation such as (1) AND/OR logic and (2) SET-RESET flip-flop operation were successfully obtained in the logic gates. In addition to the present experimental results, some problems and future prospects are also discussed.

In this paper we study on the stability of an operating points of a nonlinear resistive circuits including transistors. A set of sufficient conditions for the operating point to be unstable are proposed. These conditions are a generalization of the well-known negative difference resistance (NDR) criteria.

In this paper, we present an error concealment method to recover damaged blocks for block-based image coding schemes. Imperfect transmission of image data results in damaged blocks in the reconstructed images. Hence recovering damaged image blocks is needed for reliable image communications. To recover damaged blocks is to estimate damaged blocks from the correctly received or undamaged neighborhood information with a priori knowledge about natural images. The recovery problem considered in our method is to estimate a larger block, which consists of a damaged block and the undamaged neighborhood, from the undamaged neighborhood. To find an accurate estimate, a set of the feature vectors is introduced and an estimate is expressed as a linear combination of the feature vectors. The proposed method recoveres damaged blocks by projecting the undamaged neighborhood information onto the feature vectors. The sequential projections onto the feature vectors algorithm is proposed to find the projection coefficients of the feature vectors to minimize the squared difference of an estimate and the undamaged neighborhood information. We tested our algorithm through computer simulations. The experimental results showed the proposed method ourperforms the frequency domain prediction method in the PSNR values by 4.0-5.0dB. Tthe reconstructed images by the proposed method provide a good subjective quality as well as an objective one.

A digital neural network approach is presented for the multilayer channel routing problem with the objective of crosstalk minimization in this paper. As VLSI fabrication technology advances, the reduction of crosstalk between interconnection wires on a chip has gained important consideration in VLSI design, because of the closer interwire spacing and the circuit operation at higher frequencies. Our neural network is composed of N M L digital neurons with one-bit output and seven-bit input for the N-net-M-track-2L-layer problem using a set of integer parameters, which is greatly suitable for the implementaion on digital technology. The digital neural network directly seeks a routing solution of satisfying the routing constraint and the crosstalk constraint simultaneously. The heuristic methods are effectively introduced to improve the convergence property. The performance is evaluated through solving 10 benchmark problems including Deutsch difficult example in 2-10 layers. Among the existing neural networks, the digital neural network first achieves the lower bound solution in terms of the number of tracks in any instance. Through extensive simulation runs, it provides the best maximum crosstalks of nets for valid routing solutions of the benchmark problems in multilayer channels.

Microcellular radio direct-sequence code division multiple access (DC-CDMA) system using optical link to connect their base stations to a central station is a solution of cost-effective and efficient spectrum reuse to meet the growing demand for mobile communications. In addition to the inherent multiuser interference (MUI) of CDMA signals, the system capacity is significantly reduced by a nonlinear distortion (NLD) due to the nonlinearity of optical link. In this paper, a two-stage cancellation technique is introduced into the system to cancel both the MUI and the NLD. It is performed at the receiver of the central station where the random ingredients of all user signals are estimated, and the MUI and the NLD are rebuilt and removed from the received signal. The validity of the cancellation technique is theoretically analyzed and shown by the numerical results. The analytical method and its results are also applicable to other general nonlinear CDMA.

In this paper we suggest the "goodness" of models using the imformation criterion AIC. The information criterion AIC is a statistic to estimate the badness of models. When we usually make the fuzzy rules, we aim to minimize inference error and the number of rules. But these conditions are the criteria to acquire an optimum rule-model by using the training data. In the general case of fuzzy reasoning, we aim to minimize the inference error for not only given training data, but also unknown data. So we have introduced a new information criterion based on AIC into the appraised criterion for estimating the acquired fuzzy rules. Experimental results are given to show the validity of using AIC.

The present study investigated the human ability to selectively process pictures and words in free recall. We explored whether successful bias towards a subset of priority items occurs at the expense of the remaining items-i.e., whether successful priority item bias necessitates the dumping of information related to non-priority items. It has been shown that an increase in the percentage of correct recalls to items given priority in the pre-test instructions induces a decrease in the percentage of correct recalls for non-priority items. Even in a free recall experimental paradigm, the information dumping phenomenon was observed. However, there were no effects of stimulus presentation time and stimulus modality (picture vs. word) on the percentage of correct recalls detected.

Methods of automatically adjusting delay time and feedback gain in controlling chaos by delayed feedback control are proposed. These methods are based on a gradient-descent procedure minimizing the squared error between the current state and the delayed state. The method of adjusting delay time and that of adjusting feedback gain are applied to controlling chaos in numerical calculations of Rossler Equation and Duffing equation, respectively. Both methods are confirmed to be successful.

Several types of transmission-line coupling are analyzed to use in one- and two-dimensional active antenna arrays, and a method is developed to scan the beam of the arrays using the mutual locking theory. To compensate the undesired effect of strong radiative coupling of the nearest neighbor elements on the phased array performance, addition of resistive stubs to the end elements is proposed. In a 14 array it was observed that after the connection of resistive stubs, the scanning range of the array increased considerably. The effect of oscillator amplitudes on the phased array behavior is explored numerically. In the experiments main beam of 22 and 33 active antenna arrays were steered up to 25 and 15, respectively in the H-plane.

In this paper, we derive the mean message waiting times in a local area network that uses the Demand-Priority Access Method. We model the system as a two-priority M/G/1 queue with switchover time between service periods. This switchover time accounts for the polling and port selection performed by the repeater after each message transmission. The service discipline is non-preemptive and the length of the switchover time is dependent upon the priority class of the preceding message served as well as that of the message to be served next. The dependency in the switchover times is motivated by the polling and port selection operation of the protocol and it makes the analysis much more involved. In order to avoid the complexities of an exact analysis, we make some independence assumptions and thus obtain an approximate solution. Laplace-Stieltjes transforms of the stationary probability distribution functions for the waiting time of high- and normal-priority messages are derived, and subsequently, the expressions for the mean message waiting times. Numerical results computed using these expressions are verified using simulations which model the actual protocol. These numerical results which are shown to be accurate can be easily computed with widely available mathematical software.

This paper reports the thermal stability of particulate media, which include Co-Fe oxide, CrO2, and thick and thin MP tapes. By measuring the time decay of magnetization at room temperature, fluctuation fields were obtained as a function of reverse applied field. It was clarified that the fluctuation field has a constant and minimum value when the reverse applied field is equal to coercivity. Minimum fluctuation fields for the four particulate tapes were measured at several environmental temperatures ranging from -75 to +100. It was also clarified that the fluctuation field normalized by remanence coercivity increases as the environmental temperature increases for all tapes, indicating that it is a good measure of thermal stability. Activation volumes were also deduced as a function of temperature.

A neural network of massively interconnected digital neurons is presented for the total coloring problem in this paper. Given a graph G (V, E), the goal of this NP-complete problem is to find a color assignment on the vertices in V and the edges in E with the minimum number of colors such that no adjacent or incident pair of elements in V and E receives the same color. A graph coloring is a basic combinatorial optimization problem for a variety of practical applications. The neural network consists of (N+M) L neurons for the N-vertex-M-edge-L-color problem. Using digital neurons of binary outputs and range-limited non-negative integer inputs with a set of integer parameters, our digital neural network is greatly suitable for the implementation on digital circuits. The performance is evaluated through simulations in random graphs with the lower bounds on the number of colors. With a help of heuristic methods, the digital neural network of up to 530, 656 neurons always finds a solution in the NP-complete problem within a constant number of iteration steps on the synchronous parallel computation.

A new scheme based on hierarchical information organization and situation awareness to support network manager in failure localization is proposed. This paper integrates the situation theory for the needs of fault management to model the states and events. As the result, the proposed information model includes four fault management viewpoints to support situational, functional, logical and physical analysis within the respective networks. Object-oriented analysis is applied to construct the information. The correlation of network situation is derived by description logic. The proposed classification algorithm is applied to solve the situation awareness problem. By using this proposal the correlation performance is enhanced to logarithmic order.

The performance of a noncoherent parallel matched-filter (MF) acquisition scheme with a reference filter (RF) is evaluated for a direct-sequence/spread-spectrum multiple access (DS/SSMA) packet radio system in a mobile cellular environment. This acquisition scheme employs a RF to estimate the variance of interference at the output of detecting MF. Acquisition-based packet throughput of the parallel NM-RF scheme is derived for an AWGN and a Rayleigh fading channels. Packet throughput of a parallel MF-RF acquisition scheme is compared with those of a serial MF scheme, a serial MF-RF scheme, and a parallel MF. From the numerical results, it is shown that the packet throughput decreases with the number of users in the system, and increases with the preamble length. Imperfect power control causes packet throughput to decrease especially when the power control error is large. The considerations in this paper can be applied to the reverse link (mobile-to-base station) design of a DS/SSMA system for packet-type services.