A novel treatment technique for DMSO wastewater

We have developed an efficient treatment technique for wastewater containing dimethyl sulfoxide [DMSO, (CH₃)₂SO], a compound used as a photoresist stripping solvent in semiconductor manufacturing processes. Generally, wastewater containing organic compounds can be treated biologically, but with DMSO wastewater, biological treatment is not available because noxious compounds are produced that harm the environment. Here, we present an effective DMSO wastewater treatment technique in which we add an oxidizing agent and irradiate the wastewater with ultraviolet light to prevent damage to the environment. The use of hydrogen peroxide (H₂O₂) as an oxidizing agent in combination with ultraviolet irradiation causes DMSO to decompose promptly into methanesulfonic acid (MSA, CH₃SO₂OH). With continued treatment, the resultant MSA decomposes gradually into the inorganic compound sulfuric acid (H ₂SO₄). In this reactive route, no noxious compounds are generated. We confirmed that MSA can be biologically treated comparatively easily, and that by combining the initial ultraviolet irradiation/H₂O₂ addition treatment to rapidly produce MSA with a biological treatment to convert the MSA to H ₂SO₄, the total processing can be treated at very low cost. These treatment techniques make use of the characteristically high reactivity of DMSO and are very effective as a means of treating DMSO wastewater     

An efficient technique for eigenspace-based adaptive interferencecancellation

This paper presents a technique for the computation of the interference subspace for eigenspace-based interference cancellation. Using a subarray partitioning scheme, we construct the interference subspace from the subarray interference subspaces. In the case of uniform linear arrays, the proposed technique has the advantages of reclaiming the lost degrees of freedom due to signal blocking and reduced computational burden over existing techniques. The proposed technique also possesses the capabilities to cope with the case of using nonuniform linear arrays in the environment of partially correlated signals. A computer simulation example is provided for illustration and comparison     

An efficient solution technique for discrete-time queues fed by heterogeneous traffic

During the past couple of years, a lot of effort has been put into solving all kinds of Markov modulated discrete-time queueing models, which occur, almost in a natural way, in the performance analysis of slotted systems, such as asynchronous transfer mode (ATM) multiplexers and switching elements. However, in most cases, the practical application of such solutions is limited, because of the large state space that is usually involved. In this paper we try to take a first step towards obtaining approximate solutions for a discrete-time multiserver queueing model with a general heterogeneous Markove modulated cell arrival process, which allows accurate predictions concerning the behaviour of the buffer occupancy in such a model and still remains tractable, both from an analytical and a computational point of view. We first introduce a solution technique which leads to a closed-form expression for the joint probability generating function of the buffer occupancy and the state of the arrival process, from which an expression for V(z), the probability generating function of the buffer occupancy is easily derived. On the basis of this result we propose an approximation for the boundary probabilities, which reduces all calculations to an absolute minimum. In addition, we show how accurate data for the distribution of the buffer occupancy can be obtained, by using multiple poles of V(z) in the geometric-tail approximation of the distribution. ©1997 by John Wiley & Sons, Ltd.     

An efficient noise isolation technique for SOC application

A highly efficient CMOS process technique of suppressing the transmission of high-frequency noise induced by spiral inductors, ultrafast-switching MOS gates, or supply ringing through silicon substrate has been attained. The isolated n/sup +/-pocket structure formed by a promising process technique designed in this work has proven to be most effective in guarding vulnerable devices from remnant high-frequency noise roaming in the substrate among the structures we have used in the experiment: p/sup +/ guard ring, proton implant, and pocket structures. Excellent noise suppression efficiency of -75 dB with source and sense separated by only 21 /spl mu/m at 1 GHz has been achieved for the test keys with n/sup +/-pocket structure in contrast to -38 dB at 1GHz of unprotected devices. The isolated n/sup +/-pocket structure has manifested itself to possess the potential of becoming a key technology for mixed-mode circuits in future success of Si-based wireless communication system-on-chip (SOC) applications.     

An efficient technique for evaluating direct-sequencespread-spectrum multiple-access communications

A technique is presented for obtaining bounds on the average probability of error for direct-sequence spread-spectrum multiple-access (DS/SSMA) communications. The technique is of interest because it yields arbitrarily right bounds, involves a small amount of computation, avoids numerical integrations, and applies to many types of detection. As an illustration, the technique is applied to binary DS/SSMA communications, an additive white Gaussian noise channel, and a coherent correlation receiver. It is assumed that all the signature sequences are deterministic. Each transmitter is assumed to have the same power, although the approach can accommodate the case of transmitters with unequal powers. Expressions are given for the density functions of the random variables that model the multiple-access interference. These expressions are used to obtain arbitrarily tight upper and lower bounds on the average probability of error without making a Gaussian approximation or performing numerical integrations to incorporate the effects of multiple-access interference     

An efficient crest factor reduction technique for wideband applications

This paper describes a new efficient crest factor reduction technique for wideband applications. The technique is based on using peak cancellation to reduce the peak-to-average power ratio (PAPR) of the input signal. Conventional iterative peak cancellation requires several iterations so as to converge into the targeted PAPR, since filtering causes peak re-growth. The proposed algorithm is able to eliminate several iterations, which subsequently saves hardware resources. In numerical simulations using four WCDMA carriers, it achieves a PAPR of 5.7 dB with a fixed EVM of 10%. A 240 W PEP Class AB power amplifier was utilized to verify the performance of the proposed technique and demonstrate the efficiency gains. The measured results demonstrate that this algorithm can enhance the efficiency of our PA by up to 6.6%, when compared to the efficiency without the PAPR technique.     

An efficient nonlinear circuit simulation technique

This paper proposes a novel method for the analysis and simulation of integrated circuits (ICs) with the potential to greatly shorten the IC design cycle. The circuits are assumed to be subjected to input signals that have widely separated rates of variation, e.g., in communication systems, an RF carrier modulated by a low-frequency information signal. The proposed technique involves two stages. Initially, a particular order result for the circuit response is obtained using a multiresolution collocation scheme involving cubic spline wavelet decomposition. A more accurate solution is then obtained by adding another layer to the wavelet series approximation. However, the novel technique presented here enables the reuse of results acquired in the first stage to obtain the second-stage result. Therefore, vast gains in efficiency are obtained. Furthermore, a nonlinear model-order reduction technique can readily be used in both stages making the calculations even more efficient. Results will highlight the efficacy of the proposed approach     

An efficient cooperative technique for power-constrained multiuser wireless network

Cooperative communication plays an important role in wireless networks by improving network connectivity, spectrum efficiency, power, and communication reliability. Moreover, cooperative communication also facilitates the development of a well-organized approach in order to improve the quality of wireless terminals. Besides, it enables the utilisation of communication resources by allowing the nodes and pathways in a network to cooperate with one another via data transmissions. To control a wireless network, cooperative communication must manage its power to improve a network’s energy efficiency, capacity and reliability. When information is transmitted at a higher power, this decreases the lifespans of both the nodes and the network itself. Thus, controlling over the transmission of power is essential to obtain a sufficient level of bit-error-rate (BER) performance at the receiver. Relay nodes can improve system performance by reducing power consumption. Moreover, the decode-and-forward method is one of the best cooperative relay protocols that can be used to achieve better system performance in power constraints and BERs. In the present paper, system model containing source, destination and relay node is analysed. One cooperative scheme which including decode and forward is employed and investigated. At the experimental and simulation levels, the present paper showed that the power in the transmitters was observed and calculated in order to show the savings which are resulting from the use of relay nodes.     

An efficient multiplexing technique for packet-switched voice/datanetworks

The authors propose a multiplexing frame structure that makes it possible to transmit voice messages synchronously without loss or clipping of contents. This scheme has discrete delay characteristics, and provides a simple play-out method for reproduction of voice signal. The authors investigate its performance by obtaining the cumulative distribution of delay of voice packets and the mean waiting time of data packets. It is concluded that this synchronous frame structure can easily be applied to enhance services with various transmission rates, such as flow control of message streams, node congestion control, and service-class or throughput-class negotiation of channels without significant degradation of trunk utilization     

An efficient power reduction technique for CMOS flash analog-to-digital converters

An efficient power reduction technique for CMOS flash analog-to-digital converter (ADC) is presented. The presented technique adopts the procedure with a simple coarse comparison first followed by a finer comparison later. Our ADC design does not decrease the total number of comparators, though it is able to reduce the power consumption. Subject to time signal controlling, the manipulation is to interchangeably shut down the comparator sections for the coarse comparison function. Experimental results show that this new method consumes about 48.14 mW at 400 MHz with 3.3 V supply voltage in TSMC 0.35 μm 2P4 M process. Compared with the traditional flash ADC, our low power method can reduce up to 47.8% in power consumption. The DNL of our proposed flash ADC is 0.5 LSB, the INL is 0.7 LSB, and the ENOB is 5.75 bits. The chip area occupies 0.4 × 0.9 mm² without I/O pads.     

An efficient technique for modeling and synthesis of automotiveengine sounds

This paper presents a new method for modeling and synthesis of automotive engine sounds using a deterministic-stochastic signal decomposition approach. First, the deterministic component is extracted using a synchronous discrete Fourier transform method and this is subtracted out from the original signal. Next, the (residual) stochastic component is modeled (and synthesized) using a new multipulse excited time-series modeling technique. The effectiveness of the proposed methodology is demonstrated using recorded data sets of actual engine sounds. The results of both numerical and subjective assessment tests are presented     

An efficient inter-unit interference reduction technique for a MSTTD system

A multiple space-time transmit diversity (MSTTD) detection scheme on quasi-static Rayleigh flat-fading channels is proposed. The proposed detection algorithm first determines the candidates for M units each using a QR decomposition, and computes a reference metric for a full-length vector consisting of the first candidates at each unit. Then it performs a more likely searching simply by comparing the reference metric with other candidates such that an inter-unit interference can be effectively eliminated. Through these procedures it can approach the ML performance with less complexity even compared to an improved Schnorr-Euchner (ISE) scheme.     

An optimization technique for efficient channel allocation in cellular network

For today’s wireless mobile communication systems, efficient use of limited radio spectrum with minimum interferences is required. Itinvestigates an Optimal Genetic Algorithm approach (GA) for Hybrid Channel allocation (NP hard) focusing on reduction in interference in cellular Network. Obtained an interference graph based fitness function to enhance the performance of HCA for interference reduction. It is shown that the use of integer genetic representation for Crossover and mutation operation enhances the speed of GA leading to less computation time. Comparison of proposed method is done with reported literature for KUNZ 4 which results in less co-channel and co-site interference depicted by interfering edges and also number of generations required are less. The result for KUNZ 1, KUNZ 2 and KUNZ 3 are obtained with minimum interference along with computation time.     

An efficient technique for analyzing deep level transient spectroscopy data

A novel Deep Level Transient Spectroscopy (DLTS) method is introduced. The technique uses two data points taken from a DLTS capacitive transient to make a direct calcu-lation for the emission rate. The method is valid for all points of a thermal scan, as opposed to Lang’s original DLTS, which can only calculate the emission rate at the DLTS peaks. A complete Arrhenius plot can be constructed using one to four temper-ature scans. The method is additionally applied to simulated noise. Electron traps in Silicon are investigated with the new technique, using laboratory data. A comparison is made between this new method, the original DLTS of Lang, and recent developments made by other authors.     

An efficient uplink transmission technique for IDMA based on time-reversal

In this paper, we propose an efficient uplink transmission technique for interleave-division multiple access (IDMA) systems based on time-reversal (TR) technique (named as TDR-IDMA). In TDR-IDMA systems, the time-reversed version of the channel impulse responses (TR-CIR) obtained from the uplink is used to process the received signal preceding the elementary signal estimator (ESE) at the receiver. By exploiting the weak correlations of multi-paths for different users, the signal to interference and noise ratio (SINR) at the beginning of turbo-like detection of TDR-IDMA becomes significantly higher than that of the traditional IDMA. As a result, substantially less number of iterations is needed for the convergence in the proposed TDR-IDMA as compared with traditional IDMA. Our proposed technique effectively breaks the bottleneck of multi-user detection (MUD) in IDMA receiver, and the receiver's complexity is approximately independent of the number of the multi-path channels.     

一种高效的Internet上语音包丢失恢复技术

提出了一种高效的Internet上语音包丢失恢复技术,采用了基于奇偶校验码的加载式前向纠错编码(PPFEC)技术,可以在网络存在丢包情况下无损恢复大部分丢失帧信息。此外,本文将PPFEC技术与语音编码的错误隐藏技术相结合,提出了一种基于保护重要信息的FEC编码,得到更优的解码质量和带宽的性能折衷。客观音质实验表明,本文方法在各种丢包率情况下表现出良好的效果。     

An efficient curved-wire integral equation solution technique

Computation of the currents on curved-wires by integral equation methods is often inefficient when the structure is tortuous but the length of wire is not large relative to the wavelength at the frequency of operation. The number of terms needed in an accurate piecewise straight model of a highly curved-wire can be large, yet, if the total length of wire is small relative to the wavelength, the current can be accurately represented by a simple linear function. A new solution method for the cured-wire integral equation is introduced. It is amenable to uncoupling of the number of segments required to accurately model the wire structure from the number of basis functions needed to represent the current. This feature lends itself to high efficiency. The principles set forth can be used to improve the efficiency of most solution techniques applied to the curved-wire integral equation. New composite basis and testing functions are defined and constructed as linear combinations of other commonly used basis and testing functions. We show how the composite basis and testing functions can lead to a reduced-rank matrix, which can be computed via a transformation of a system matrix created from traditional basis and testing functions. Supporting data demonstrate the accuracy of the technique and its effectiveness in decreasing matrix rank and solution time for curved-wire structures     

An efficient low-complexity technique for MLSE equalizers for linear and nonlinear channels

In this paper, a novel sequence equalizer, which belongs to the family of cluster-based sequence equalizers, is presented. The proposed algorithm achieves the maximum likelihood solution to the equalization problem in a fraction of computational load, compared with the classic maximum likelihood sequence estimation (MLSE) equalizers. The new method does not require the estimation of the channel impulse response. Instead, it utilizes the estimates of the cluster centers formed by the received observations. Furthermore, a new cluster center estimation scheme, which exploits the intrinsic dependencies among the cluster centers, is proposed. The new center estimation method exhibits enhanced performance with respect to convergence speed, compared with an LMS-based channel estimator. Moreover, this gain in performance is obtained at substantially lower computational load. The method is also extended in order to cope with nonlinear channels. The performance of the new equalizer is tested with several simulation examples, using both the quadrature phase shift keying (QPSK) and the 16-quadrature amplitude modulated (QAM) signaling schemes for linear and nonlinear communication channels.     

阵列结构辐射与散射特性分析的迭代方法

给出一种适用于有限阵列结构辐射及特性分析的迭代方法。该法不受阵列单元排布形式、单元电流分布情况和单元数量的限制，对有限周期和非周期阵列的分析都有着较高的计算效率和稳定的收敛性。文中着重以有限周期及非周期带栅的散射分析为例，验证了方法的有效性，并同有限阵格林函数法和逐元法作了比较，给出了有关的数值计算结果。