Approximate Expression of Bit Error Rate in Uplink MC-CDMA Systems with Equal Gain Combining

Uplink multicarrier code-division multiple-access (MCCDMA) with equal gain combining (EGC) over Nakagami fadingchannels is considered. An improved expression which is a feasiblealternative for the bit error rate (BER) performance evaluation ofMC-CDMA signals is proposed. Simulated annealing algorithm isemployed to obtain the optimum value of the coef?cients belongingto the proposed expression. Numerical examples show that the performance curves computed by the improved expression are in goodagreement with the results obtained by the exact expression. Thus,the proposed expression can improve the accuracy of BER performance evaluation that has been realized by the approximate expression

High-order exponential approximations for the Gaussian Q-function obtained by genetic algorithm

This article presents new and accurate approximations for the Gaussian Q-function, which is an important tool in the field of communication theory. A genetic algorithm was employed to find the optimum coefficients of the proposed approximations. The accuracy of the new approximations was examined and compared with those of previous works in the literature. It was shown that the presented high-order exponential approximations provide better accuracy compared to the previously introduced approximations, in general, at the cost of slightly increased mathematical complexity.This article presents new and accurate approximations for the GaussianQ-function, which is an important tool in the field of communication theory. Agenetic algorithm was employed to find the optimum coefficients of the proposedapproximations. The accuracy of the new approximations was examined andcompared with those of previous works in the literature. It was shown that thepresented high-order exponential approximations provide better accuracycompared to the previously introduced approximations, in general, at the costof slightly increased mathematical complexity

A novel method of support vector machine to compute the resonant frequency of annular ring compact microstrip antennas

An application of support vector machine (SVM) to compute the resonant frequency at dominant mode TM11 of annular ring compact microstrip antennas (ARCMAs) is presented in this paper. ARCMAs have some useful features; resonant modes can be adjusted by controlling the ratio of the outer radius to the inner radius. The resonant frequencies of 100 ARCMAs with varied dimensions and electrical parameters in accordance with UHF band covering GSM, LTE, WLAN, and WiMAX applications were simulated with IE3D™ which is a robust numerical electromagnetic computational tool. Then, the SVM model was built with simulation data and 88 simulated ARCMAs were operated for training and the remaining 12 ARCMAs were used for testing this model. The proposed model has been confirmed by comparing with the suggestions reported elsewhere via measurement data published earlier in the literature, and it has further validated on an ARCMA operating at 3 GHz fabricated in this study. The obtained results show that this technique can be successfully used to compute the resonant frequency of ARCMAs without involving any sophisticated methods. The novelty of the approach described here is to offer ease of designing the process using this method

Invasive Mould Infections In Intensive Care Units: Epidemiology, Microbiologic Diagnosis And Antifungal Resistance

Invasive fungal infections present with a rising incidence and high morbidity and mortality rates. Among these infections are those due to moulds which draw particular attention per the diagnostic difficulties and higher mortality rates. While a relative decrease is observed in mortality rates regarding the use of prophylactic, empirical or preemptive antifungal regimens, there is a tendency of increase in antifungal resistance rates. Furthermore, due to increase in number of cases with immunosuppression, infections caused by rare and emerging moulds are now more frequently observed. Breakthrough infections, nosocomial infections, and infections due to risk factors other than immunosuppression are also a clinical concern. Diagnosis of invasive mould infections requires a multidisciplinary approach with clinical, radiological, histopathological and microbiological data. However, nonspecificity of clinical signs and radiological findings and difficulties in differentiation of infection and colonization are major problems in patients with invasive mould infections in intensive care units. Limited availability of routine microbiology laboratories with adequate facilities in mycological diagnostics and problems in specificity and sensitivity of diagnostic tests for intensive care unit patients result in further difficulties in diagnosis of these infections. In this review article, epidemiological data and microbiological diagnostic methods for invasive mould infections in intensive care units were reviewed per the published reports and the recommendations of current guidelines. Finally, antifungal resistance and clinical impact of resistance were discussed.WoSScopu

Position only pattern nulling of linear antenna array by using a clonal selection algorithm (CLONALG)

In this paper, a clonal selection algorithm (CLONALG) based on clonal selection principle of immune system has been used for null steering in the antenna radiation pattern by controlling only the element positions of a linear array. Numerical examples of Chebyshev pattern with the single, multiple and broad nulls imposed at the directions of interference are given to show the accuracy and flexibility of the CLONALG. The sensitivity of the achieved patterns due to small variations of the element positions is also investigated by truncating the element positions

Pattern nulling of linear antenna arrays by controlling only the element positions with the use of improved touring ant colony optimization algorithm

An efficient search technique based on the improved touring ant colony optimization algorithm is presented for pattern nulling by controlling only the position of linear antenna array elements. The relative importance between the null depth level and the maximum sidelobe level is also considered by introducing a set of weighting factors in the cost function constructed for the improved touring ant colony optimisation algorithm. The frequency memory feature of tabu search is used in the improved touring ant colony optimization algorithm. To verify the validity of the technique, illustrative examples of Chebyshev pattern with the imposed single, multiple and broad nulls are given

Accurate and simple synthesis formulas for coplanar waveguides

Simple and accurate closed-form formulas obtained by using a differential evolution algorithm are presented for the synthesis of coplanar waveguides (CPW). The results of the synthesis formulas proposed in this article are compared with those of the quasi-static analysis, the synthesis formulas reported by the other researchers and also the experimental works available in the literature. The accuracy of the proposed synthesis formulas is found to be better than 0.75% for 9256 CPWs samples. (C) 2008 Wiley Periodicals, Inc

Interference suppression of linear antenna arrays by phase-only control using a clonal selection algorithm

In this paper, an efficient technique based on clonal selection algorithm (CLONALG) for linear antenna array pattern synthesis with null steering by controlling only the element excitation phases is presented. The CLONALG is an evolutionary computation method inspired by the clonal selection principle of human immune system. To show the versatility and flexibility of the proposed CLONALG, some examples of Chebyshev array pattern with the imposed single, multiple and broad nulls are given. The sensitivity of the nulling patterns due to small variations of the element phases is also investigated. (C) 2007 The Franklin Institute. Published by Elsevier Ltd. All rights reserved

Shaped-beam pattern synthesis of linear antenna arrays with the use of a clonal selection algorithm

In this paper, the position-only, amplitude-only, and amplitude-phase synthesizes for the shaped-beam patterns of the linear antenna arrays have been achieved by using the clonal selection algorithm (CLONALG). The CLONALG is a relatively novel evolutionary optimization method based on the clonal selection principle of the human immune system. Numerical examples of the pencil, flat-topped, and cosecant patterns are given. Numerical results show that the CLONALG is capable of synthesizing the array patterns with a good performance both in the shaped region and in the sidelobe region