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Performance Analysis of a Mark.vian Queue with Impatient Customers and Work.ng Vacation

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Journal of the Operations Research Society of China 2023年第1期11卷 133-156页

作者： shakir Majid Department of Mathematics University of LadakhLeh CampusLeh194101India

In this paper,we consider the impatient customers in M/M/1 queueing model under variant work.ng vacation *** customer’s impatience is due to its arrival during a work.ng vacation period,where the service rate of the customer is lower than a normal busy *** the system is non-empty when the server returns from the work.ng vacation,the server resumes the normal service ***,the server will tak. successive work.ng vacations till it reaches the maximum number of k.work.ng vacations and then the server remains idle until the next ***-form probabilities are obtained by using the identities involving beta functions and degenerate hypergeometric functions,and the performance measures of the system are derived using generating *** stochastic decomposition structures of the mean queue length and mean waiting time are *** effects of the system parameters on some performance measures had been numerically illustrated.

关键词： Mark.vian queue Variant work.ng vacations Probability generating function

Antioxidant Activities of Ok.a Protein Concentrate and Isolate after Enzymatic Hydrolysis

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Food and Nutrition Sciences 2018年第9期9卷 1066-1077页

作者： Abdulk.reem A. k.reem k.alidah A. shakir Marie k. Walsh Department of Food Science College of Agriculture Tikrit University Tikrit Iraq Department of Food Science College of Agriculture University of Baghdad Baghdad Iraq Department of Nutrition Dietetics and Food Sciences Utah State University Logan UT USA

Three different proteolytic enzymes (pepsin, trypsin and papain) were used to prepare ok.a seed protein concentrate and ok.a seed protein isolate hydrolysates. The hydrolysates were assayed for antioxidant properties using radical scavenging, reducing power and metal chelating assays. The highest degree of hydrolysis (after 360 min) for ok.a protein isolates was 35.20%, 35.21% and 10.53% for pepsin, papain and trypsin respectively. The highest degree of hydrolysis (after 360 min) for ok.a protein concentrates was 26.8%, 28.59% and 6.47% for pepsin, papain and trypsin respectively. Pepsin hydrolysates showed higher metal chelating activity and radical scavenging activity than trypsin and papain hydrolysates. Trypsin hydrolysates showed the lowest antioxidant activities, which may be due to the low degree of hydrolysis. In general, for antioxidant activity, there was an increase in activity with an increase in the degree of hydrolysis. Similar antioxidant activity was found in both the ok.a protein isolate and concentrate hydrolysates except for metal chelating activity which was higher in ok.a protein isolate hydrolysates. This may be due to the higher ash concentration in the concentrates (9.4% in concentrates vs. 2.6% in isolates). In this study, pepsin hydrolysates with a final DH of 35.2% showed higher reducing power and metal chelating activity than trypsin and papain hydrolysates. Ok.a protein hydrolysates were found to have varying levels of antioxidant activity, which was dependent on the specificity of the protease and proportional to the degree of hydrolysis achieved.

关键词： Ok.a Protein Enzymatic Hydrolysis Antioxidant Properties

Bifunctional catalysts of Co3O4@GCN tubular nanostructured （TNS） hybrids for oxygen and hydrogen evolution reactions

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Nano Research 2015年第11期8卷 3725-3736页

作者： Muhammad Tahir Nasir Mahmood Xiaoxue Zhang Tariq Mahmood Faheem. k. Butt Imran Aslam M.Tanveer Faryal Idrees Syed k.alid Imran shakir Yiming Yan Jijun Zou Chuanbao Cao Yanglong Hou Research Centre of Materials Science Beijing Institute of Technology Beijing 100081 China Department of Materials Science and Engineering Peldng University Beijing 100081 China Beijing k.y Laboratory for Chemical Power Source and Green Catalyst School of Chemical Engineering and Environment Beijing Institution of Technology Beijing 100081 China Sustainable Energy Technologies (SET) center building No 3 Room 1c23 College of Engineering King Saud University PO BOX 800 Riyadh 11421 Kingdom of Saudi Arabia k.y Laboratory for Green Chemical Technology of the Ministry of Education School of Chemical Engineering and Technology Tianjin University Collaborative Innovative Center of Chemical Science and Engineering (Tianjin) Tianjin 300072 China

Catalysts for oxygen and hydrogen evolution reactions （OER/HER） are at the heart of renewable green energy sources such as water splitting. Although incredible efforts have been made to develop efficient catalysts for OER and HER, great challenges still remain in the development of bifunctional catalysts. Here, we report a novel hybrid of Co3O4 embedded in tubular nanostructures of graphitic carbon nitride （GCN） and synthesized through a facile, large-scale chemical method at low temperature. Strong synergistic effects between Co3O4 and GCN resulted in excellent performance as a bifunctional catalyst for OER and HER. The high surface area, unique tubular nanostructure, and composition of the hybrid made all redox sites easily available for catalysis and provided faster ionic and electronic conduction. The Co3O4@GCN tubular nanostructured （TNS） hybrid exhibited the lowest overpotential （0.12 V） and excellent current density （147 mA/cm^2） in OER, better than benchmark. IrO2 and RuO2, and with superior durability in alk.line media. Furthermore, the Co3O4@GCN TNS hybrid demonstrated excellent performance in HER, with a much lower onset and overpotential, and a stable current density. It is expected that the Co3O4@GCN TNS hybrid developed in this study will be an attractive alternative to noble metals catalysts in large scale water splitting and fuel cells.

关键词： carbon nitride cobalt oxide bifunctional catalyst oxygen evolution reaction hydrogen evolution reaction

Circular neighbor-balanced designs using cyclic shifts

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Science China Mathematics 2009年第10期52卷 2243-2256页

作者： IQBAL Ijaz TAHIR M. H. GHAZALI Syed shakir Ali Department of Statistics Bahauddin Zakariya University Department of Statistics The Islamia University of Bahawalpur

In agriculture experiments, the response on a given plot may be affected by the treatments on neighboring plots as well as by the treatments applied to that plot. In this paper we consider such type of situations and construct circular neighbor-balanced designs (CNBDs) by the method of cyclic shifts or sets of shifts. An important feature of this method is that the properties of a design can be easily obtained from the sets of shifts instead of constructing the actual block. of the design. That is, the off-diagonal elements of the concurrence matrix can be easily obtained from the sets of shifts. Since the suggested designs are circular, balanced and binary, so they are universally optimal.

关键词： A-optimal circular designs cyclic shifts treatment-balanced designs universally optimal 05B05 62k.5 62k.0

Disrupted Maturation of Prefrontal Layer 5 Neuronal Circuits in an Alzheimer’s Mouse Model of Amyloid Deposition

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Neuroscience Bulletin 2023年第6期39卷 881-892页

作者： Chang Chen Jing Wei Xiaok.ang Ma Baomei Xia Neha shakir Jessica k.Zhang Le Zhang Yuehua Cui Deveroux Ferguson Shenfeng Qiu Feng Bai Department of Neurology Affiliated Drum Tower HospitalMedical School of Nanjing UniversityNanjing210008China Basic Medical Sciences University of Arizona College of Medicine-PhoenixPhoenixAZ85004USA

Mutations in genes encoding amyloid precursor protein(APP)and presenilins(PSs)cause familial forms of Alzheimer’s disease(AD),a neurodegenerative disorder strongly associated with *** is currently unk.own whether and how AD risk. affect early brain development,and to what extent subtle synaptic pathology may occur prior to overt hallmark.AD *** mutant APP/PS1 over-expression mouse lines are k.y tools for studying the molecular mechanisms of AD *** these lines,the 5XFAD mice rapidly develop k.y features of AD pathology and have proven utility in studying amyloid plaque formation and amyloidβ(Aβ)-induced *** reasoned that transgenic mutant APP/PS1 over-expression in 5XFAD mice may lead to neurodevelopmental defects in early cortical neurons,and performed detailed synaptic physiological characterization of layer 5(L5)neurons from the prefrontal cortex(PFC)of 5XFAD and wild-type littermate controls.L5 PFC neurons from 5XFAD mice show early APP/Aβ***-cell patch-clamp recording at an early post-weaning age(P22–30)revealed functional impairments;although 5XFAD PFC-L5 neurons exhibited similar membrane properties,they were intrinsically less *** addition,these neurons received smaller amplitude and frequency of miniature excitatory synaptic *** functional disturbances were further corroborated by decreased dendritic spine density and spine head volumes that indicated impaired synapse *** biotinylation followed by Western blot analysis of PFC-L5 tissue revealed that 5XFAD mice showed reduced synaptic AMPA receptor subunit GluA1 and decreased synaptic NMDA receptor subunit *** with this,patch-clamp recording of the evok.d L23>L5 synaptic responses revealed a reduced AMPA/NMDA receptor current ratio,and an increased level of AMPAR-lack.ng silent *** results suggest that transgenic mutant forms of APP/PS1 overexpression in 5XFAD mice leads to early deve

关键词： Alzheimer’s disease Mouse model Synaptic plasticity Long-term potentiation Cortical circuit Electrophysiology Learning and memory

Optimization of Culture Conditions to Produce Phytase from <i>Aspergillus tubingensis Sk.</i>

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Food and Nutrition Sciences 2017年第7期8卷 733-745页

作者： Samar S. Qasim k.alida A. shakir A. B. Al-Shaibani Marie k. Walsh Department of Food Science College of Agriculture University of Baghdad Baghdad Iraq College of Biotechnology Al-Nahrain University Baghdad Iraq Department of Nutrition Dietetics and Food Sciences Utah State University Logan UT USA

The effects of nutrients and physical conditions on phytase production were investigated with a recently isolated strain of Aspergillus tubingensis Sk. under solid state fermentation on wheat bran. The nutrient factors investigated included carbon source, nitrogen source, phosphate source and concentration, metal ions (salts) and the physical parameters investigated included inoculum size, pH, temperature and fermentation duration. Our investigations revealed that optimal productivity of phytase was achieved using wheat bran supplemented with: 1.5% glucose. 0.5% (NH4)2SO4, 0.1% sodium phytate. Additionally, optimal physical conditions were 1 × 105 spore/g substrate, initial pH of 5.0, temperature of fermentation 30°C and fermentation duration of 96 h. Overall, a 34% improvement in phytase activity was achieved by using the optimal conditions.

关键词： Phytase Aspergillus tubingensis Sk. Solid State Fermentation Optimization

Implications COVID-19 on Performance and Energy Management in the Production Electricity

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Computers, Materials & Continua 2021年第10期69卷 895-911页

作者： Noor shakir Mahmood Ahmed Ali Ajmi Shamsul Sarip k.airur Rijal Jamaludin Hazilah Mad k.idi Hayati Abdul Talib University of Technology Ministry of Electricity GCEP/Middle region BaghdadIraq Razak.Faculty of Technology and Informatics UTMKuala Lumpur54100Malaysia

The COVID-19 pandemic has directly impacted the electric power industry;the energy sector has experienced huge losses in electricity *** losses have also affected the reliability of communication and employees’performance,hence destabilizing the electric power *** article aims at achieving two ***,analyzing the impact of the COVID-19 pandemic on the communication of performance(human error and human factors)and energy management in electricity ***,to develop a conceptual framework.model to alleviate effects of the pandemic on the power sector and then improve energy management and human *** paper involves investigating the influence of the COVID19 pandemic on the global production of electricity in the first quarters of 2019 and 2020.A conceptual model was developed based on a case ***,to ensure reliability,a variable,namely COVID-19,was used as a moderator to examine the effects of the independent and dependent *** results show that scores for the internet of things(IoT)with awareness and communication(A&C)and work.lace environment management were high with Cronbach’s alpha value of 0.87 for the IoT and 0.89 for A&*** numbers are important indicators of factors that could affect performance and energy management and should not be overlook.d by the top *** results also indicate that the pandemic has had a direct effect on the electricity production sector,and the conceptual framework.model revealed that COVID-19,as a moderator,has a direct effect on the variables that significantly affect the improvement of both energy management and employee *** case study’s results confirm the poor performance in power plant maintenance and operation,in which human error would increase especially in Iraqi power plants that have not yet adopted any internationally recognized standards for energy *** paper contributes to the literature studying COVID-19’s impa

关键词： Communication internet of things decision mak.ng energy management performance work.lace environment

Computational Calculations of Molecular Properties and Molecular Dock.ng of New and Reference Cephalosporins on Penicillin Binding Proteins and Various β-Lactamases

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Journal of Pharmacy and Pharmacology 2016年第5期4卷 212-224页

作者： shakir Mahmood Alwan Department of Pharmaceutical Chemistry College of Pharmacy University of Baghdad Baghdad Bab Al-Moadham P. O. Box14026 Iraq

An approach of using molinspiration calculations and molecular dock.ng on PBPs （penicillin-binding proteins） and certain β-lactamases is employed to predict the molecular properties, bioactivity and resistance of newer and reference cephalosporins. The previously synthesized cephalosporins 1-8 and reference cephalosporins were subjected to extensive evaluations by calculating the molecular properties, drug-lik.ness scores on the bases of Lipinsk.＇s rule and bioactivity prediction using the method of molinspiration web-based software. The TPSA （topological polar surface area）, OH-NH interactions, n-violation and the molinspiration Log partition coefficient （miLogP） values were also calculated. The investigated cephalosporins were subjected to molecular dock.ng study on PBPs （lpyy） and on β-lactamases produced by S. aureus, k. pneumonia, E. coil and P. auroginosa using 1-click.dock.ng website. Molecular properties of 1-8 recorded higher ＂FPSA than cephalexin and were lower than the reference cephalosporins and do not fulfill the requirements for Lipinsk.＇s rule. Bioactivities of 1-8 were predicted to be less and their dock.ng scores on PBPs were comparable to those of the reference cephalosporins, particularly ceftobiprole. The references recorded various dock.ng scores on the above β-lactamases and as expected, cefiobiprole recorded the lowest scores on all β-lactarnases. Cephalosporins 1-8 recorded various dock.ng scores on β-lactamases. Molecular dock.ng studies on PBPs and β-lactamases are considered as very useful, reliable and practical approach for predicting the bioactivity scores and to afford some information about the stability and selectivity of the newly proposed cephalosporins against β-lactamases of certain pathogenic microbes, such as P. auroginosa and MRSA, by recording the relative dock.ng scores in comparison with those of reference cephalosporins.

关键词： Cephalosporins Molinspiration Molecular dock.ng β-lactamases Lipinsk.'s rule.

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基于DBSCAN的人脸聚类

基于DBSCAN的人脸聚类

作者： RIAZ shakir FARUk. 华南理工大学

学位级别：硕士

本论文主要关注如下问题:在许多未标记的人脸图像数据集中,将人脸图像聚类成数据中存在的不同身份。该问题在社交媒体和司法鉴定时有着广泛的应用。近些年来,视频监控在许多领域得到了广泛的关注,包括司法鉴定,公共安全,交通控制和住宅... 详细信息

本论文主要关注如下问题:在许多未标记的人脸图像数据集中,将人脸图像聚类成数据中存在的不同身份。该问题在社交媒体和司法鉴定时有着广泛的应用。近些年来,视频监控在许多领域得到了广泛的关注,包括司法鉴定,公共安全,交通控制和住宅监控等。如今,警方通过从视频监控所拍摄的视频或照片来对犯罪分子进行搜查。然而,人工从视频中找到相关目标将会耗费大量的人力和物力,进而促进了自动化的发展。本文将重点研究基于密度的噪声应用空间聚类(DBSCAN)算法,该方法是一种高效且有效的方法,具有良好的性能,并且取得比其他聚类方法(如,k.means,谱聚类和Rank.Order)更高的精度。基于密度的聚类算法DBSCAN的核心思想是聚类中的每个对象必须在其邻域内具有一定数量的其他对象。与其他聚类算法相比,DBSCAN具有许多优点,例如,它可以检测任意形状的聚类,并且对异常值等具有鲁棒性。因此,DBSCAN在过去几十年中引起了很多研究兴趣,并且有着许多扩展和应用。本文将研究五种不同的聚类算法,并在不同数据集上进行测试。五种聚类算法是k.means,threshold clustering,mean shift,DBSCAN和rank.order。在第一个实验中,本文将这些聚类方法在LFW子集和全集上进行测试。本文还在ISIS人脸数据集上进行测试,以评估这些聚类算法的性能。本文通过实验发现,threshold clustering在F-measure和误报数量上有着非常好的性能。除此之外,DBSCAN在整个实验过程中都取得了较好的效果。因此,DBSCAN是一种高效的人脸聚类方法.

关键词： DBSCAN 人脸聚类聚类