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Narrow-band interference suppression in Time-Division-Duplex CDMA systems using preprocessing techniques

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Journal of Systems Engineering and Electronics 2008年第5期19卷 893-895页

作者： paeiz azmi Nooshin Tavakkoli Dept. of Electrical Engineering Tarbiat Modares Univ

This letter presents two preprocessing techniques for narrow-band interference （NBI） rejection in Time- Division-Duplex （TDD） CDMA systems. In the proposed methods, at the transmitter, by using Karhaunen-Loeve Transform and Discrete Fourier Transform, the transmitted power is set to zero in the directions of the eigenvectors that will be severely contaminated by NBI; and therefore less part of the transmitted energy will be polluted by NBI in channel. The processing is transferred from receiver to transmitter, and thus the complexity of the receiver is significantly reduced. It is assumed that channel state information can be estimated at the transmitter because in symmetric TDD systems each receiver in turn also acts as a transmitter.

关键词： CDMA narrow-band interference pre-processing

Feasibility of a novel beamforming algorithm via retrieving spatial harmonics

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Journal of Systems Engineering and Electronics 2022年第1期33卷 38-46页

作者： NOROLAHI Jafar azmi paeiz NASIRIAN Mahdi Electrical and Computer Engineering Department Tarbiat Modares UniversityTehran 14115Iran Department of Electrical and Computer Engineering Sharif University of TechnologyTehran 11365Iran

This paper introduces an algorithm for beamforming systems by the aid of multidimensional harmonic retrieval(MHR).This algorithm resolves problems,removes limitations of sampling and provides a more robust beamformer.A new sample space is created that can be used for estimating weights of a new beamforming called spatial-harmonics retrieval beamformer(SHRB).Simulation results show that SHRB has a better performance,accuracy,and applicability and more powerful eigenvalues than conventional beamformers.A simple mathematical proof is *** changing the number of harmonics,as a degree of freedom that is missing in conventional beamformers,SHRB can achieve more optimal outputs without increasing the number of spatial or temporal *** will demonstrate that SHRB offers an improvement of 4 dB in signal to noise ratio(SNR) in bit error rate(BER) of 10~(-4) over conventional *** the case of direction of arrival(DOA) estimation,SHRB can estimate the DOA of the desired signal with an SNR of-25 dB,when conventional methods cannot have acceptable response.

关键词： multi-input-multi-output(MIMO) beamforming spatial and temporal signal processing multidimensional harmonic retrieval(MHR) space-time signal processing array signal processing

Automatic modulation classification using modulation fingerprint extraction

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Journal of Systems Engineering and Electronics 2021年第4期32卷 799-810页

作者： NOROLAHI Jafar azmi paeiz AHMADI Farzaneh Electrical and Engineering Department Tarbiat Modares UniversityTehran 14115Iran

An automatic method for classifying frequency shift keying(FSK),minimum shift keying(MSK),phase shift keying(PSK),quadrature amplitude modulation(QAM),and orthogonal frequency division multiplexing(OFDM)is proposed by simultaneously using normality test,spectral analysis,and geometrical characteristics of in-phase-quadrature(I-Q)constellation *** the extracted features are unique for each modulation,they can be considered as a fingerprint of each *** show that the proposed algorithm outperforms the previously published methods in terms of signal-to-noise ratio(SNR)and success *** example,the success rate of the proposed method for 64-QAM modulation at SNR=11 dB is 99%.Another advantage of the proposed method is its wide SNR range;such that the probability of classification for 16-QAM at SNR=3 dB is almost *** proposed method also provides a database for geometrical features of I-Q constellation *** comparing and correlating the data of the provided database with the estimated I-Q diagram of the received signal,the processing gain of 4 dB is *** can be mentioned about the preference of the proposed algorithm are low complexity,low SNR,wide range of modulation set,and enhanced recognition at higher-order modulations.

关键词： automatic modulation classification in-phase-quadrature(I-Q)constellation diagram spectral analysis feature based modulation classification

Analysis of the high-temperature dry sliding behavior of CoCrFeNiTi0.5Alx high-entropy alloys

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Friction 2020年第1期8卷 198-207页

作者： azmi ERDOGAN Mustafa Sabri GOK Sakin ZEYTIN Department of Metallurgy and Materials Engineering Faculty of EngineeringBartın UniversityBartın 74100Turkey Department of Mechanical Engineering Faculty of EngineeringBartın UniversityBartın 74100Turkey Department of Metallurgy and Materials Engineering Faculty of EngineeringSakarya UniversitySakarya 54100Turkey

In this study,CoCrFeNiTi0.5Alx high‐entropy alloys were produced by induction melting and their dry sliding wear behavior was examined at different *** addition to face‐centered cubic(FCC)phases,low amounts of a tetragonal phase were detected in the microstructures of alloys without Al and microscratches were formed by wear particles on the worn surfaces of the alloy *** body‐centered cubic(BCC)phases were detected in the alloy with 0.5Al and a fatigue‐related extrusion wear mechanism was detected on the worn *** alloy specimen with a high Al content exhibited the best wear *** wear tracks were formed in single‐phase BCC intermetallic alloys at room temperature and they exhibited a higher wear strength at high temperatures when compared to other samples.

关键词： high‐entropy alloy dry sliding wear friction intermetallic

Gold anomaly ranking based on stream sediment geochemistry in the Fariman–Kashmar axis, NE Iran

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Acta Geochimica 2021年第2期40卷 135-149页

作者： Hassan azmi Parviz Moarefvand Abbas Maghsoudi Department of Mining and Metallurgical Engineering Amir Kabir University of TechnologyTehranIran Geological Survey of Iran Northeast TerritoryMashhadIran

One of the essential tasks accelerate the decision-making process in mineral exploration projects is ranking anomalous *** this study,we used fourteen geologic maps(at scale 1:100,000)in areas where systematic geochemical explorations were conducted in the Fariman-Kashmar axis in northeast Iran to conduct the anomaly *** all these maps,samples were consistently prepared to be analyzed through statistical and geostatistical *** first,anomaly separation was carried out by fractal methods that resulted in the detection of 308 anomalous samples in 128 *** samples were classified into three groups of first,second,and thirdorder anomalies,whose number of anomalous samples were calculated based on this ranking *** factors,including the average concentration of each anomaly,its surface area,and the number of its samples,were used to rank the *** to this technique,the maximum anomaly score obtained was 172 for the Taknar area,and the minimum score was 3 for several *** validate the ranking results,some exploration operations were carried out in some of these anomalous areas in which mining operations started *** significant gold anomalous areas were introduced,which is considered an important result of this study.

关键词： Anomaly ranking Fractal model Exploration decision Gold exploration Geochemistry exploration

Performance assessment of an inline horizontal swirl tube cyclone for gas-liquid separation at high pressure

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Journal of Natural Gas Chemistry 2011年第6期20卷 565-567页

作者： Nurhayati Mellon azmi M. Shariff Department of Chemical Engineering Universiti Teknologi PETRONAS Bandar Sri Iskandar Perak 31750 Malaysia

The application of swirl tube cyclone for gas-liquid separation is attractive due to its small size and weight. However, very scarce information on the performance of the swirl tube cyclone especially at high operating pressure emulating actual field condition was published in journals. Performance assessment was usually done at a low operating pressure using either air-water, air-fine particle mixtures or dense gas such as SF6 . This paper fills the existing gaps and reports the initial findings on the performance assessment of a horizontal swirl tube cyclone for gas-liquid separation operating at a flow rate of 5 MMSCFD at 40-60 bar operating pressure.

关键词： compact separator cyclone swirl tube natural gas separation

Thermal analysis of a constructal T-shaped porous fin with simultaneous heat and mass transfer

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Chinese Journal of Chemical Engineering 2017年第9期25卷 1121-1136页

作者： Saheera azmi Hazarika Tuhin Deshamukhya Dipankar Bhanja Sujit Nath Department of Mechanical Engineering National Institute of Technology

The present work establishes an analytical model for computing the temperature distribution, fin efficiency and optimum design parameters of a constructal T-shaped porous fin operating in fully wet condition. For more practical results, this study considers a cubic polynomial relationship between the humidity ratio of saturated air and the corresponding fin surface temperature. The temperature distribution has been determined by solving the highly non-linear governing equations using a semi-analytical transformation technique called Differential Transform Method. A comparison of the results with that of a numerical model shows that this transformation method is a very efficient and convenient tool for solution of non-linear problems. The effects of various geometric, thermo-physical and psychometric parameters on the temperature distribution, fin efficiency and optimum design condition have been investigated. Also, a comparison has been presented between solid and porous fins and the results point out that by selecting an appropriate value of porosity, the heat transfer rate can be increased than the corresponding solid fin.

关键词： Constructal Porous Mass transfer Analytical Optimization Differential Transform Method

Sintering Behavior and Microstructure Evolution of Mechanically Alloyed W-Bronze Composite Powders by Two-step Ball Milling Process

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Journal of Materials Science & Technology 2013年第1期29卷 59-69页

作者： Kahtan S. Mohammed azmi Rahmat Khairel R. Ahmad School of Materials Engineering Universiti Malaysia Perlis

The miscibility of W in Sn and Cu is extremely poor. Sintering of W-bronze composites to their full density is proved to be difficult. To tackle this problem, the ball milling process of the W-bronze powder mixture proposed in this study was split into two steps. In the first step, the softness of Sn powder was exploited to modify the surface morphology of W particles. In the second step, Cu was added to the ball milled mixture. To achieve this goal, four 50 wt% W-bronze compact sets of different powder precursors and activator additions were produced. The sintering process was performed at 1150 ℃. The two-step ball milled powder yielded sintered compacts of homogeneous microstructure of fine polygonal W grains dispersed in bronze matrix. They showed the highest hardness and densification levels. The sintered density, microstructure, hardness and densification mechanisms of the sintered compacts were investigated, examined and evaluated using different metallographic, microscopic and measurement facilities.

关键词： Metal matrix composites Mechanical alloying Sintering Microstructure Scanning electron microscopy

Prostate cancer stem cells： molecular characterization for Largeted therapy

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Asian Journal of Andrology 2012年第5期14卷 659-660页

作者： Asfar S azmi Fazlul H Sarkar Department of Pathology Karmanos Cancer Institute Wayne State University School of Medicine Detroit MI 48201 USA Department of Oncology Karmanos Cancer Institute Wayne State University School of Medicine Detroit M148201 USA

The article published recently in Cell Stem Cell from the laboratory of Dr Tang showed the existence and molecular fingerprints of prostate cancer stem cells （CSCs）, and this report opens newer ave- nues for developing and designing novel therapeutic strategies for targeted elimina- tion of these CSCs toward prostate cancer therapy.

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