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A thermodynamic perspective on electrode poisoning in solid oxide fuel cells

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1449-1455页

作者： Kevin Huang department of Mechanical Engineering University of South CarolinaColumbiaUSA

A critical challenge to the commercialization of clean and high-efficiency solid oxide fuel cell(SOFC)technology is the insuf-ficient stack lifespan caused by a variety of degradation mechanisms,which are associated with cell components and chemical *** components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions,whereas the latter regards impurities in feedstocks of oxidant(air)and reductant(fuel).This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in *** discussion focuses on using thermodynamic ana-lysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr,CO_(2),H_(2)O,and SO_(2) and in the anode by species such as S(or H_(2)S),SiO_(2),and P_(2)(or PH_(3)).The author hopes the presented fundamental insights can provide a theoretical foundation for search-ing for better technical solutions to address the critical degradation challenges.

关键词： impurities air fuel reaction activity

A critical fault detection analysis & fault time in a UPFC transmission line

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Protection and Control of Modern Power Systems 2019年第1期4卷 24-33页

作者： S.K.Mishra L.N.Tripathy School of ee Research ScholarKIIT UniversityBhubaneswar751024India department of ee C.E.TBhubaneswarOdishaIndia

This paper discusses a critical study of fault detection and fault time analysis in a Unified Power Flow Controller (UPFC) transmission line. Here the Discrete Wavelet Transform (DWT) and Discrete Fourier Transform (DFT) approach are used for processing the faulty current signal to obtain fundamental current signal. The extracted fault current signals from the current transformer are fed to DWT and DFT approach for computing spectral energy (SE). The differential spectral energy (DSE) of phase currents are evaluated by taking the difference of SE obtained at sending and receiving end. The DSE is the key factor for deciding the fault in any of the phase or not. The Daubechy mother wavelet (db4) is used here because of its high accuracy of detection with less processing time. The novelty of the scheme is that it can accurately detect the critical fault variation of the line. Number of simulations are validated at the extreme condition of the line and compared to other conventional existing scheme. Multi-phase fault in double circuit line, CT saturation, UPFC operating condition (series voltage and angle), UPFC location and wind speed variation including wind farm simulation are validated to verify the performance of the scheme. The advantages of the scheme is that it works effectively to detect the fault at any stage of critical condition of the line and fault detection time remains within 20 msec (less than one cycle period). This scheme protects both internal and external zone including parameter variation of the line.

关键词： DSE Fault detection UPFC Threshold Fault time

A NOVEL ZERO-FORCING PRECODING METHOD FOR MULTI-CELL MIMO SYSTEMS

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Journal of Electronics(China) 2013年第2期30卷 152-158页

作者： Zhou Wen Jiang Yongquan Fan Lisheng ee department of Shantou University

Precoding methods at the Base Station (BS) can be used to deal with the inter-cell interference and improve the signal quality of the user especially at the cell edge. In this paper, a novel Zero-Forcing (ZF) precoding method is proposed and investigated for multi-cell Multi-Input Multi-Output (MIMO) systems. We propose a relaxed ZF precoding method by relaxing the ZF criterion to some degree so that the inter-cell interference may not be zero. Complexity analysis shows that compared with the conventional ZF method, the additional computation complexity for the proposed method is trivial. Simulation results show that the proposed relaxed ZF method has better performance than the conventional ZF method in terms of the sum-rate, especially at low Signal to Noise Ratio (SNR).

关键词： Coordinated multipoint transmission/reception Multi-Input Multi-Output (MIMO) Coordinated beamforming

Outcomes of a non-randomised audit of single pigtail suture stents in urolithiasis management of Asian patients in Singapore

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Asian Journal of Urology 2024年第2期11卷 324-330页

作者： ee Jean Lim Zhen Wei Choo Reshma Mangat Pradeep Durai Sarvajit Biligere Yiquan Tan Loh Hin Yeung Marcus Nicole Andrea Seet Li Ting Chin Tiong Heng Stefania Ferreti Vineet Gauhar Urology department Singapore General HospitalSingapore Urology department Tan Tock Seng HospitalSingapore Urology department Ng Teng Fong HospitalSingapore Urology department Azienda Ospedaliera-Uiversitaria(Hospital and University of Parma)ParmaItaly

Objective:Double-J(DJ)ureteric stents are commonly placed perioperatively for semirigid or flexible ureteroscopic renal *** is believed that lesser stent material within the bladder mitigates stent-related *** study aimed to evaluate the J-Fil ureteral stent,a single pigtail suture stent compared with conventional DJ stent in relation to stent symptoms in an Asian population undergoing ureterorenal ***:Based on internal audit committee recommendation approval,the records of 50 patients retrieved,available data of 41 patients who were prospectively enrolled into two groups(Group 1[J-Fil stent group],n=21 and Group 2[DJ stent group],n=20)between August 2020 to January 2021,were *** compared were nature of procedure,stone location and size,ease of deployment or removal,and complications.A modified universal stent symptom questionnaire was used to assess morbidity of stent symptoms within 48 h of insertion and at ***:Both groups had similar median age,distribution in male to female ratio,and stone *** overall median universal stent symptom questionnaire score at insertion was similar for bladder pain,flank or loin pain,and quality of life between Group 1 and 2;however,at removal Group 1 fared significantly better than Group 2,especially for flank or loin pain and pain at *** groups had similar ease in insertion with no hospital ***:Our audit favoured the single pigtail suture stent in Asian ureters in mitigating stent-related *** showed a good safety profile with easy deployment and *** promises a new standard in stenting.

关键词： Stent Ureteroscopy Pigtail suture stent Asianpatient Flexible ureteroscopic renal surgery

Performance Analysis of ZF and RZF in Low-Resolution ADC/DAC Massive MIMO Systems

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China Communications 2024年第8期21卷 115-126页

作者： Talha Younas Shen Jin Muluneh Mekonnen Gao Mingliang Saqib Saleem Sohaib Tahir Mahrukh Liaqat School of Electrical and Electronic Engineering Shandong University of TechnologyZibo 255000China department of Electrical and Computer Engineering COMSATS University IslamabadSahiwal Campus department of Electrical and Computer Engineering College of EngineeringDhofar UniversitySalalah 211Oman department of Electrical and Computer Engineering Addis Ababa Science and Technology UniversityAddis AbabaEthiopia department of Electrical Engineering College of Electrical and Mechanical EngineeringNUSTIslamabadPakistan

Large number of antennas and higher bandwidth usage in massive multiple-input-multipleoutput(MIMO)systems create immense burden on receiver in terms of higher power *** power consumption at the receiver radio frequency(RF)circuits can be significantly reduced by the application of analog-to-digital converter(ADC)of low *** this paper we investigate bandwidth efficiency(BE)of massive MIMO with perfect channel state information(CSI)by applying low resolution ADCs with Rician *** start our analysis by deriving the additive quantization noise model,which helps to understand the effects of ADC resolution on BE by keeping the power constraint at the receiver in *** also investigate deeply the effects of using higher bit rates and the number of BS antennas on bandwidth efficiency(BE)of the *** emphasize that good bandwidth efficiency can be achieved by even using low resolution ADC by using regularized zero-forcing(RZF)combining *** also provide a generic analysis of energy efficiency(ee)with different options of bits by calculating the energy efficiencies(ee)using the achievable *** emphasize that satisfactory BE can be achieved by even using low-resolution ADC/DAC in massive MIMO.

关键词： low-bit analog-digital converter massive(multiple-input-multiple-output)MIMO minimum mean square error(MMSE) regularized zero forcing zero forcing

SWITCHED-CURRENT FILTER DESIGN USING CASCADED SECTIONS

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Journal of Electronics(China) 1993年第3期10卷 273-278页

作者：吴杰 department of ee Hunan University Changsha 410082

A new analogue sampled-data active device, named as a switched-current operationalamplifier (SIOA), is presented. The use of active circuit elements may simplify drawing the circuitdiagram significantly greatly and may permit easier analysis and synthesis of SI networks. Anumber of all pole and elliptic (second-or third-order) switched-current (SI) filters are derivedfrom the switched capacitor prototypes. These can be used as simple self-contained filters or asfilter sections in the cascaded realizations of a higher order transfer functions. To illustrate theapproach, a fifth-order low-pass filter is designed.

关键词： Circuit theory and design Switched-Current Active filter

Opposition-based differential evolution for IIR system identification problem

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International Journal of Modeling, Simulation, and Scientific Computing 2014年第4期5卷 49-105页

作者： P.Upadhyay R.Kar D.Mandal S.P.Ghoshal department of ECE NIT Durgapur West BengalIndia department of ee NIT Durgapur West BengalIndia

Nature inspired optimization algorithms have made substantial step towards solving of various engineering and scientific real-life *** achieved for those evolution-ary optimization techniques are due to simplicity and flexibility of algorithm *** this paper,optimal set of filter coefficients are searched by the evolutionary optimiza-tion technique called Opposition-based Differential Evolution(ODE)for solving infinite impulse response(IIR)system identification ***-based numbering con-cept is embedded into the primary foundation of Differential Evolution(DE)technique metaphorically to enhance the convergence speed and the performance for finding the optimal *** population is generated with the evaluation of a solution and its opposite solution by fitness function for choosing potent solutions for each iteration *** this competent population,faster convergence speed and better solution quality are *** and balanced search in multidimensional problem space is accomplished with judiciously chosen control parameters for mutation,crossover and selection adopted in the basic DE *** tested against standard benchmark examples,for same order and reduced order models,the simulation results establish the ODE as a competent candidate to others in terms of accuracy and convergence speed.

关键词： IIR adaptive filter RGA PSO DE ODE evolutionary optimization techniques mean square error coefficient convergence

A new fractal algorithm to model discrete sequences

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Chinese Physics B 2010年第9期19卷 274-278页

作者：翟明岳 Heidi Kuzuma James W. Rector School of ee Engineering North China Electric Power University department of Civil Engineering University of California Lawrence Berkeley Laboratory

Employing the properties of the affine mappings, a very novel fractal model scheme based on the iterative function system is proposed. We obtain the vertical scaling factors by a set of the middle points in each affine transform, solving the difficulty in determining the vertical scaling factors, one of the most difficult challenges faced by the fractal interpolation. The proposed method is carried out by interpolating the known attractor and the real discrete sequences from seismic data. The results show that a great accuracy in reconstruction of the known attractor and seismic profile is found, leading to a significant improvement over other fractal interpolation schemes.

关键词： fractal interpolation the vertical scaling factors iterative function system seismic data

Clinical features of gastroesophageal reflux disease and erosive esophagitis:Insights from patients undergoing esophagogastroduodenoscopy in resource-limited Ethiopia

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World Journal of Gastroenterology 2024年第34期30卷 3883-3893页

作者： Firehiwot A Mengistie Abate B Shewaye Abel T Tasamma Zekarias S Ayalew department of Internal Medicine Addis Ababa UniversityAddis Ababa 1176Addis AbabaEthiopia department of Internal Medicine Rheum Rheumatology and Internal Medicine Specialty ClinicAddis Ababa 1000Addis AbabaEthiopia Division of Gastroenterology and Hepatology Department of Internal MedicineAdera Medical and Surgical CenterAddis Ababa 1000Addis AbabaEthiopia

BACKGROUND Gastroesophageal reflux disease(GERD)is a common disease worldwide with varying clinical presentations and risk *** data for Africa is lacking,but an increasing trend is expected due to demographic and epidemiological *** endoscopic studies for general gastrointestinal disorders have shown some patients with erosive esophagitis(ee),no studies in Ethiopia have investigated the clinical characteristics,risk factors,and severity of GERD using esophagogastroduodenoscopy(EGD).AIM To assess the clinical features of GERD in Ethiopian patients who underwent EGD and determine the severity and risk factors of *** We conducted a multicenter,retrospective cross-sectional study of 221 patients diagnosed with GERD and endoscopic findings of ee at Trauma Associated Severe Hemorrhage and Amniotic Membrane Stem Cell between January 2019 and August *** were collected from electronic medical records and phone call *** used descriptive statistics and binary logistic regression analysis with SPSS version 26 to identify the association between variables with a statistical significance set at P valueee was diagnosed in 71.1%of patients,followed by LA-B(14.9%),LA-C(7.7%),and LA-D(5.9%).Multivariate analysis showed that age 50 or above,presence of bleeding,and endoscopic findings of duodenitis/duodenopathy were significantly associated with severe ee(Pee,*** Most of the patients had milder ee with fewer ***,severe ee was more prevalent in older patients and those with duodenitis/duodenopathy.

关键词： Gastroesophageal reflux disease Erosive esophagitis Hiatal hernia Esophagogastroduodenoscopy Heart burn