This letter presents the characteristics of complex antenna factors of a resistor loaded dipole antenna with a balun consisting of two coaxial feeders (coaxial cable balun). The resistor loading is used to realize dipole antennas with higher fidelity than unloaded dipole equivalents. The complex antenna factor for a resistor loaded dipole antenna with coaxial cable balun is derived by extending the power loss concepts. The numerical results show that the series resistor loaded dipole antenna offers higher fidelity than the unloaded dipole. The result of the calculated complex antenna factors are in good agreement with that of the measured results.

Refactoring is one of the promising techniques for improving program design by means of program transformation with preserving behavior, and is widely applied in practice. However, it is difficult for engineers to identify how and where to refactor programs, because proper knowledge and skills of a high order are required of them. In this paper, we propose the technique to instruct how and where to refactor a program by using a sequence of its modifications. We consider that the histories of program modifications reflect developers' intentions, and focusing on them allows us to provide suitable refactoring guides. Our technique can be automated by storing the correspondence of modification patterns to suitable refactoring operations. By implementing an automated supporting tool, we show its feasibility. The tool is implemented as a plug-in for Eclipse IDE. It selects refactoring operations by matching between a sequence of program modifications and modification patterns.

In this paper, based on Equivalent Active Flow, we propose a novel technique called Approximate Fairness Dropping, which is able to approximate fairness by containing misbehaving flows' access queue opportunity with low time/space complexity. Unlike most of the existing Active Queue Management schemes (e.g., RED, BLUE, CHOKE), Approximate Fairness Dropping does not drop the packets whose arriving rate is within the maximum admitted rate, so it protects the well-behaving flows against misbehaving ones, moreover, improves the throughput and decreases the queuing delay. Our simulations and analyses demonstrate that this new technique outperforms the existing schemes and closely approximates the "ideal" case, where full state information is needed.

Supporting Quality of Service (QoS) over the Internet is a very important issue and many mechanism have been already devised or are under way towards achieving this goal. One of the most important approaches is the class-based architecture, which provides a scalable mechanism for QoS support in a TCP/IP network. Class-based service differentiation can be realized without resource reservation, admission control and traffic policing. However, the resulting services are only relative. While it is, in principle, not feasible to provision for absolute guarantees without admission control and/or traffic policing, such a service can be reasonably well emulated using adaptive rate allocation at the link scheduler of routers. In this paper, we propose mechanism for link scheduler of router that achieve emulated absolute and other relative guarantees using dynamic weighted fair queueing (DWFQ) combining with class packet dropping. The weights of DWFQ are frequently adjusted to current load conditions and based on prediction of realistic class traffic. These mechanisms can realize many approaches to QoS guarantees and class-based differentiation.

We have proposed a neural network called the Lagrange programming neural network with polarized high-order connections (LPPH) for solving the satisfiability problem (SAT) of propositional calculus. The LPPH has gradient descent dynamics for variables and gradient ascent dynamics for Lagrange multipliers, which represent the weights of the clauses of the SAT. Each weight wr increases according to the degree of unsatisfaction of clause Cr. This causes changes in the energy landscape of the Lagrangian function, on which the values of the variables change in the gradient descent direction. It was proved that the LPPH is not trapped by any point that is not a solution of the SAT. Experimental results showed that the LPPH can find solutions faster than existing methods. In the LPPH dynamics, a function hr(x) calculates the degree of unsatisfaction of clause Cr via multiplication. However, this definition of hr(x) has a disadvantage when the number of literals in a clause is large. In the present paper, we propose a new definition of hr(x) in order to overcome this disadvantage using the "min" operator. In addition, we extend the LPPH to solve the constraint satisfaction problem (CSP). Our neural network can update all neurons simultaneously to solve the CSP. In contrast, conventional discrete methods for solving the CSP must update variables sequentially. This is advantageous for VLSI implementation.

This paper investigates the design curves of class E amplifier with nonlinear capacitance for any output Q and finite dc-feed inductance. The important results are; 1) the capacitance nonlinearity strongly affects the design parameters for low Q, 2) the value of dc-feed inductance is hardly affected by the capacitance nonlinearity, and 3) the input voltage is an important parameter to design class E amplifier with nonlinear capacitance. By carrying out PSpice simulations, we show that the simulated results agree with the desired ones quantitatively. It is expected that the design curves in this paper are useful guidelines for the design of class E amplifier with nonlinear capacitance.

It is well known that TCP does not fully utilize the available bandwidth in fast long-distance networks. To solve this scalability problem, several high speed transport protocols have been proposed. They include HighSpeed TCP (HS-TCP), Scalable TCP (S-TCP), Binary increase control TCP (BIC-TCP), and H-TCP. These protocols increase (decrease) their window size more aggressively (slowly) compared to standard TCP (STD-TCP). This paper aims at evaluating and comparing these high speed transport protocols through computer simulations. We select six metrics that are important for high speed protocols; scalability, buffer requirement, TCP friendliness, TCP compatibility, RTT fairness, and responsiveness. Simulation scenarios are carefully designed to investigate the performance of these protocols in terms of the metrics. Results clarify that each high speed protocol successfully solves the problem of STD-TCP. In terms of the buffer requirement, S-TCP and BIC-TCP have better performance. For TCP friendliness and compatibility, HS-TCP and H-TCP offer better performance. For RTT fairness, BIC-TCP and H-TCP are superior. For responsiveness, HS-TCP and H-TCP are preferred. However, H-TCP achieves a high degree of fairness at the expense of the link utilization. Thus, we understand that all the proposed high speed transport protocols have their own shortcomings. Thus, much more research is needed on high speed transport protocols.

We have developed a promising method for suppressing moisture condensation that prevents insulation failures in surge protectors. By analyzing surge protectors retrieved from the field, we found that electrolytic corrosion had occurred due to the encroachment of sea salt, the application of bias voltages, and the condensation of moisture. To suppress moisture condensation, a key factor in insulation failure, we applied a previously developed humidity-control package containing water-absorbent polymer. We experimentally optimized the design and functionality of the polymer package. We found that sealing the feed-through apertures alone was not enough to suppress moisture inflow and that a relatively large amount of water-absorbent polymer was needed to prevent water condensation in environments with extremely high humidity for extended periods of time. Laboratory experiments and field tests demonstrated that our optimized package minimized humidity fluctuation and thus moisture condensation in surge protectors, thereby preventing insulation failure. Application of this method to installed surge protectors greatly reduced the insulation failure rate.

A novel frequency domain training sequence and the corresponding carrier frequency offset (CFO) estimator are proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency-selective fading channels. The proposed frequency domain training sequence comprises two types of pilot tones, namely distinctively spaced pilot tones with high energies and uniformly spaced ones with low energies. Based on the distinctively spaced pilot tones, integer CFO estimation is accomplished. After the subcarriers occupied by the distinctively spaced pilot tones and their adjacent subcarriers are nulled for the sake of interference cancellation, fractional CFO estimation is executed according to the uniformly spaced pilot tones. By exploiting a predefined lookup table making the best of the structure of the distinctively spaced pilot tones, computational complexity of the proposed CFO estimator can be decreased considerably. With the aid of the uniformly spaced pilot tones generated from Chu sequence with cyclically orthogonal property, the ability of the proposed estimator to combat multipath effect is enhanced to a great extent. Simulation results illustrate the good performance of the proposed CFO estimator.

Modification of ITU-R P.1411 model to enhance the prediction accuracy in urban environments having variable heights of buildings is proposed in this paper by introducing two kinds of novel correction factors. One is considering the relationship of the highest building height and the transmitter (Tx) antenna height, and the other is considering the effect of receiver (Rx) position on crossroads. After introducing two correction factors, the prediction accuracy is shown to be improved.

In this paper, we introduce a low computing post processing algorithm to simultaneously suppress blocking and ringing artifacts of compressed video sequences. A new regularization function to incorporate smoothness to neighboring pixels is defined, where the function is composed of four sub-functions combined with pixel-based data fidelity and smoothing terms. Therefore, the solution can be obtained without inverse matrix or vector-matrix computation, so that low complexity implementation is possible. In addition, the regularization parameter controlling the relative importance between the data fidelity and the degree of smoothness is estimated from the available overhead information in decoder, such as, macroblock type and quantization step size. The experimental results show the capability and efficiency of the proposed algorithm.

In this paper we propose a novel spatial fading simulator to evaluate the performance of an array antenna and show its spatial stochastic characteristics by computer simulation based on parameters verified by experimental data. We introduce a cavity-excited circular array (CECA) as a fading simulator that can simulate realistic mobile communication environments. To evaluate the antenna array, two stochastic characteristics are necessary. The first one is the fading phenomenon and the second is the angular spread (AS) of the incident wave. The computer simulation results with respect to fading and AS show that CECA works well as a spatial fading simulator for performance evaluation of an antenna array. We first present the basic structure, features and design methodology of CECA, and then show computer simulation results of the spatial stochastic characteristics. The results convince us that CECA is useful to evaluate performance of antenna arrays.

This paper presents a new bearing fault detection algorithm based on analyzing singular points of vibration signals using the Haar wavelet. The proposed Haar Fault Detection (HFD) algorithm is compared with a previously-developed algorithm associated with the Morlet wavelet. We also substitute the Haar wavelet with Daubechies wavelets with larger compact supports and evaluate the results. Simulations carried on real data demonstrate that the HFD algorithm achieves a comparable accuracy while having a lower computational cost. This makes the HFD algorithm an appropriate candidate for fast processing of bearing faults.

A mode-matching technique in conjunction with the Floquet theorem is proposed to analyze the propagation characteristics of periodic circular surface waveguides. The circular waveguides are coated outside with a multilayered dielectric and have a ground plane with periodic corrugation of arbitrary profile. Three different ground corrugation profiles are examined to demonstrate the influences of the corrugation shape, depth, and width, dielectric thickness, and relative permittivity on bandstop characteristics.

As computer hardware components are achieving greater speeds, network link bandwidths are becoming wider. A number of enhancements to TCP have been developed in order to fully exploit these improvements in network infrastructures, including TCP window scale option, SACK option, and HighSpeed TCP (HSTCP) modifications. However, even with these enhancements, TCP cannot provide satisfactory performance in high-speed long-delay networks. As a means addressing this problem, gentle HighSpeed TCP (gHSTCP) has been proposed in [1]. However, its effectiveness has only been demonstrated in simulation experiments. In the present paper, a refined gHSTCP algorithm is proposed for application to real networks. The performance of the refined gHSTCP algorithm is then assessed experimentally. The refined gHSTCP algorithm is based on the original algorithm, which uses two modes (Reno mode and HSTCP mode) in the congestion avoidance phase and switches modes based on RTT increasing trends. The refined gHSTCP algorithm compares two RTT thresholds and judges which mode will be used. The performance of gHSTCP is compared with TCP Reno/HSTCP and parallel TCP mechanisms. The experimental results demonstrate that gHSTCP can provide a better tradeoff in terms of utilization and fairness against co-existing traditional TCP Reno connections, whereas HSTCP and parallel TCP suffer from the trade-off problem.

In this paper, we describe a parallel decoding-based ASR system developed of ATR that is robust to noise type, SNR and speaking style. It is difficult to recognize speech affected by various factors, especially when an ASR system contains only a single acoustic model. One solution is to employ multiple acoustic models, one model for each different condition. Even though the robustness of each acoustic model is limited, the whole ASR system can handle various conditions appropriately. In our system, there are two recognition sub-systems which use different features such as MFCC and Differential MFCC (DMFCC). Each sub-system has several acoustic models depending on SNR, speaker gender and speaking style, and during recognition each acoustic model is adapted by fast noise adaptation. From each sub-system, one hypothesis is selected based on posterior probability. The final recognition result is obtained by combining the best hypotheses from the two sub-systems. On the AURORA-2J task used widely for the evaluation of noise robustness, our system achieved higher recognition performance than a system which contains only a single model. Also, our system was tested using normal and hyper-articulated speech contaminated by several background noises, and exhibited high robustness to noise and speaking styles.

Stratospheric platforms have been recently proposed as a new wireless infrastructure for realizing the next generation of communication systems. To provide high quality services, an investigation of the wireless stratospheric platform channel is essential. This paper proposes a definition and describes an analysis of the wireless channel for the link between stratospheric platforms and terrestrial mobile users based on an experiment in a semi-urban environment. Narrowband channel characteristics are presented in terms of Ricean factor (K factor) and local mean received power over a wide range of elevation angles ranging from 10to 90. Finally, we evaluated average bit error probability based on the proposed channel model to examine the channel performance. For the environment in which the measurements were conducted, we find that elevation angles greater than 40yield better performance.

In this paper, we propose simple but effective modifications of 802.11 MAC (media access control) to resolve efficiency and fairness issues, in wireless ad-hoc networks [2]. Our proposal, based on the flow concept, incorporated faster end-to-end forwarding by assigning higher priority to a node that has packets to relay than others. After completion of end-to-end transmission, the node will be assigned a lower priority level to yield to other nodes. Simulation results show that the proposed scheme (F-MAC) significantly enhances the throughput of ad-hoc networks, while keeping fair sharing of bandwidth among mobile nodes.

The paper provides an overview of the circuit techniques for CMOS high-speed I/Os, focusing on the design issues in sub-100 nm standard CMOS. First, we describe the evolution of CMOS high-speed I/O since it appeared in mid 90's. In our view, the surge in the I/O bandwidth we experienced from the mid 90's to the present was driven by the continuous improvement of the CMOS IC performance. As a result, CMOS high-speed I/O has covered the data rate ranging from 2.5 Gb/s to 10 Gb/s, and now is heading for 40 Gb/s and beyond. To meet the speed requirements, an optimum choice of the transceiver architecture and its building blocks are crucial. We pick the most critical building blocks such as the decision circuit and the multiplexors and give detailed explanation of their designs. We describe the low-voltage operation of the high-speed I/O in view of reducing the power consumption. An example of a 90-nm CMOS 2.5 Gb/s transceiver operating off a 0.8 V power supply will be described. Operability at 0.8 V ensures that the circuits will not become obsolescent, even below the 60 nm process node.

The application of Orthogonal Space-Time Block Codes (O-STBC) as the encoding scheme in the presence of "non-quasi-static" fading was considered. A simple and efficient adaptive method of channel estimation based on the interpolation of estimates acquired at the pre-amble and post-amble of framed blocks of information is developed. Moreover, the proposed method is proven, both theoretically and by simulations, to outperform the alternative of channel tracking, despite its significant low complexity.