This paper presents a cache way enabling mechanism using branch target addresses. This mechanism uses branch prediction information to avoid the power consumption due to unnecessary cache way access by enabling only the cache way(s) that should be accessed. The proposed cache way enabling mechanism reduces the power consumption of the instruction cache by 63% without any performance degradation of the processor. An ARM1136 processor simulator and the Synopsys PrimeTime are used to perform the performance/power simulation and static timing analysis of the proposed mechanisms respectively.

The design of multi-branch optical waveguides having 3 or more output ports is not so easy as that of 2-output branches because some innovative geometry is required to realize equal power splitting. All previous studies take the same approach in which they first introduce innovative geometries and then adjust the structural parameters for equal splitting. On the other hand, we propose quite a different method where distribution of refractive index is calculated from an ideal field distribution which is synthesized artificially. The method is extended to design 3-D 4-branch waveguides. It is exemplified that 4-branch waveguides with low-loss and equal splitting can be realized by the proposed method.

A new mesh reconstruction technique, called dividing virtual belt algorithm (DVBA), is proposed for approximating the surface from a set of wire-frame contours. DVBA decomposes the branching region into a set of virtual belts and virtual canyons. A tiling technique based on the divide-and-conquer strategy is also introduced to approximate the surface from the virtual belt, and the virtual canyons are covered by a conventional polygon triangulation technique. The experimental result shows that our method works well even though there are many complicated branches in the object.

Gas or water leaks in pipes that are buried under ground or that are situated in the walls of buildings may occur due to aging or unpredictable accidents, such as earthquakes. Therefore, the detection of leaks in pipes is an important task and has been investigated extensively. In the present paper, we propose a novel leak detection method by means of acoustic wave. We inject an acoustic chirp signal into a target pipeline and then estimate the leak location from the delay time of the compressed pulse by passing the reflected signal through a correlator. In order to distinguish a leak reflection in a complicated pipeline arrangement, the reflection characteristics of leaks are carefully discussed by numerical simulations and experiments. There is a remarkable difference in the reflection characteristics between the leak and other types of discontinuity, and the property can be utilized to distinguish the leak reflection. The experimental results show that, even in a complicated pipe arrangement including bends and branches, the proposed approach can successfully implement the leak detection. Furthermore, the proposed approach has low cost and is easy to implement because only a personal computer and some commonly equipment are required.

A branch-and-bound algorithm (BB for short) is the most general technique to deal with various combinatorial optimization problems. Even if it is used, computation time is likely to increase exponentially. So we consider its parallelization to reduce it. It has been reported that the computation time of a parallel BB heavily depends upon node-variable selection strategies. And, in case of a parallel BB, it is also necessary to prevent increase in communication time. So, it is important to pay attention to how many and what kind of nodes are to be transferred (called sending-node selection strategy). In this paper, for the graph coloring problem, we propose some sending-node selection strategies for a parallel BB algorithm by adopting MPI for parallelization and experimentally evaluate how these strategies affect computation time of a parallel BB on a PC cluster network.

This paper proposes a new class of parallel branch-and-bound (B&B) schemes. The main idea of the scheme is to focus on the functional parallelism instead of conventional data parallelism, and to support such a heterogeneous and irregular parallelism by using a collection of autonomous agents distributed over the network. After examining several implementation issues, we describe a detail of the prototype system implemented over eight PC's connected by a network. The result of experiments conducted over the prototype system indicates that the proposed parallel processing scheme significantly improves the performance of the underlying B&B scheme by adaptively switching exploring policies adopted by each agent participating to the problem solving.

Collective transverse plasma modes in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions (IJJs) can be excited by the moving fluxon lattices. Progressive transformation of the standing-wave-like fluxon-lattice configuration from a triangular lattice to a rectangular lattice takes place as the dynamic fluxon-lattice modes are in resonance with the collective transverse plasma modes. In this paper, we review the progress in terahertz-frequency-range electromagnetic wave generation from the IJJs using the resonance between moving fluxon lattice and the collective transverse plasma modes.

This letter describes four-branch open-loop transmit diversity schemes that are based on group-coherent codes using space-time block codes (STBC-GCC), for orthogonal frequency-division multiplexing and code-division multiplexing (OFDM-CDM) systems. Open-loop STBC-GCC is designed for transmitting control data by two-dimensional spreading, which is achieved by applying two distinct Walsh-Hadamard (WH) codes within the same mother-code group to two different groups of transmit antennas. The simulation results demonstrated that open-loop STBC-GCC applied to two-dimensional spreading provides space diversity gains and frequency diversity gains. It can therefore be concluded that open-loop STBC-GCC is suitable for transmitting common control data or broadcast data via two-dimensional spreading OFDM-CDM.

This paper studies the electromagnetic field radiated by a return stroke, considering even the case of a direct lightning on an aircraft, in the Fraunhofer region. The work here presented is an analysis of a complete discharge case, considering the electric field due to some charged clouds, the presence of a conductive airplane immersed in this external electric field, the channels related to the lightning paths, and the interactions of the field due to the lightning return stroke with a far field located victim system. It could be divided in several steps. Firstly, the cloud-generated electric field has been calculated, and a particular model of the clouds has been introduced. For what concerns the geometrical considerations, a Koch's snowflake shaped cloud has been chosen, in order to achieve a complex geometrical model. To better fit this model with the reality a non-symmetric cloud has been created. Then, a simple aircraft model, according to those reported in literature, has been introduced. The conductive structure of the aircraft interacts with the atmospheric electric field and modifies its distribution. Furthermore, applying a boundary panel method, frequently used in subsonic incompressible aerodynamics, Laplace's equation for the electrostatic potential in the considered domain has been computed, taking into account the presence of the metallic structure. Finally, the inception points on the outer surface of the aircraft are calculated and highlighted. Beginning from those points, in which the probability of discharge is higher, a suitable lightning channel has been created, and the shape of the jagged field signal has been correlated to the tortuous path discharge, even considering the presence of branches. The total electric field given by the first discharge from the cloud to the airplane, by the second discharge from the aircraft to the ground and by the current flowing along the fuselage has been computed and calculated in a far field located observation point.

Most branch predictors use the PC information of the branch instruction and its dynamic Global Branch History (GBH). In this letter, we suggest a Branch Direction History (BDH) as the third component of the branch prediction and analyze its impact upon the prediction accuracy. Additionally, we propose a new branch predictor, direction-gshare predictor, which utilizes the BDH combined with the GBH. At first, we model a neural network with (PC, GBH, and BDH) and analyze their actual impact upon the branch prediction accuracy, and then we simulate our new predictor, the direction-gshare predictor. The simulation results show that the aliasing in Pattern History Table (PHT) is significantly reduced by the additional use of BDH information. The direction-gshare predictor outperforms bimodal predictor, two-level adaptive predictor and gshare predictor up to 15.32%, 5.41% and 5.74% respectively, without additional hardware costs.

This paper proposes an effective branch folding technique which combines branch instructions with predicted instructions. This technique can be implemented using an instruction queue, which buffers prefetched instructions. Most of the instructions in the instruction queue are forwarded to the execution unit in sequence. Branch instructions, however, are combined with predicted instructions in the instruction queue and these folded instructions are forwarded to the execution unit. Miss-prediction can be recovered by flushing folded instructions without processor state recovery and by restarting from the other path. Simulation and implementation results show that both performance and power consumption are significantly improved with little additional hardware cost.

In this letter, we study dynamic multicasting in GMPLS networks with unequal branching capability. An overlapped multicasting tree is proposed to reduce blocking probability, which can utilize the branching capabilities more efficiently than the traditional Steiner tree. A nearest node branch first heuristic is developed to find such an overlapped tree.

We develop an algorithm for a controller design method for Max-Plus Linear (MPL) systems with selective parameters. Since the conventional algorithm we proposed requires high computational load when the prediction horizon is large, two methods for reducing the calculation time are proposed. One is based upon the branch-and-bound method, and the other is to reuse the optimal solution. The effectiveness of these two methods is confirmed through numerical simulation.

This study proposes a 3 dB branch-line coupler using radial stubs to achieve reduced coupler size and simplified stub arrangement. As the electrical lengths of stubs used here are less than 90at center frequency, a method of comparing input impedances to obtain radial stubs that are equivalent to straight stubs is discussed. The frequency characteristics of the proposed coupler are derived by combining classical transmission line theory with the computed data of radial stub input impedances. The methods presented here increase possibilities for realizing reduced branch-line couplers by means of stub design. Experimental results agree well with theoretical results except for slight differences in the high frequency region.

Even in embedded processors, the accuracy in a branch prediction significantly affects the performance. In designing a branch predictor, in addition to accuracy, microarchitects should consider area, delay and power consumption. We propose two techniques to reduce the power consumption; these techniques do not requires any additional storage arrays, do not incur additional delay (except just one MUX delay) and never deteriorate accuracy. One is to look up two predictions at a time by increasing the width (decreasing the depth) of the PHT (Prediction History Table). The other is to reduce unnecessary accesses to the BTB (Branch Target Buffer) by accessing the PHT in advance. Analysis results with Samsung Memory Compiler show that the proposed techniques reduce the power consumption of the branch predictor by 15-52%.

In order to produce precise enclosures from a multi-dimensional interval vector, we introduce a sharp interval sub-dividing condition for optimization algorithms. By utilizing interval inclusion properties, we also enhance the sampling of an upper bound for effective use in the interval quadratic method. This has resulted in an improvement in the algorithm for the unconstrained optimization problem by Hansen in 1992.

Effective counteraction to Distributed Denial-of-Services (DDoS) attacks is a pressing problem over the Internet. For this counteraction, it is considered important to locate the router interfaces closest to the attackers in order to effectively filter a great number of identification jammed packets with spoofed source addresses from widely distributed area. Edge sample (ES) based Probabilistic Packet Marking (PPM) is an encouraging method to cope with source IP spoofing, which usually accompanies DDoS attacks. But its fragmentation of path information leads to inefficiency in terms of necessary number of packets, path calculation time and identification accuracy. We propose Branch Label (BL) based PPM to solve the above inefficiency problem. In BL, a whole single path information is marked in a packet without fragmentation in contrast to ES based PPM. The whole path information in packets by the BL approach is expressed with branch information of each router interfaces. This brings the following three key advantages in the process of detecting the interfaces: quick increase in true-positives detected (efficiency), quick decrease in false-negatives detected (accuracy) and fast convergence (quickness).

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 letter addresses the issue of RSVP path management in IP micro-mobility networks. We describe efficient RSVP QoS paths with a minimal impact to the existing protocol and underlying routing infrastructure. The goal of this letter is to reduce RSVP path reservation restoration latency and unnecessary control traffic caused by mobility events. We thus propose a RSVP branch-path rerouting scheme at a crossover router (CR) under IP micro-mobility networks. We show that this scheme could give a good tradeoff between the resource reservation cost and the link usage during the lifetime of a RSVP connection.

MIMO communication systems have been studied as a way to increase system capacity and to improve spectrum efficiency. This paper proposes a novel branch metric generation method for soft-decision Viterbi decoding in coded OFDM systems employing SDM (OFDM-SDM) systems, one form of MIMO communication, that employ the maximum likelihood decision (MLD) algorithm. In coded OFDM systems, the branch metric for forward error correction (FEC) is normally calculated based on received sub-carrier power level and the constellation point likelihood. This conventional approach fails in OFDM-SDM systems. In the proposed method, branch metric is derived based on the likelihood calculated by MLD algorithm, which improves FEC performance effectively. Then, availability of coded OFDM-SDM to realize wireless LANs with data rate above 100 Mbit/s in a bandwidth of 20 MHz is evaluated in office environments using required CNR calculated by computer simulation. The evaluation indicates that OFDM-SDM has the possibility of realizing 100 Mbit/s in office environments.