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Dependence of effective screening length in granular columns on bead and silo sizes and their ratio

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Chinese Physics B 2013年第5期22卷 591-594页

作者： Abdul Qadir Madad Ali Shah saeed Ahmed khan Department of Electrical Engineering Sukkur Institute of Business Administration

Apparent mass measurements at the bottom of silos have been carried out. An important parameter in the Janssen model known as the effective screening length has been investigated for different bead and silo diameters as well as of their ratios. It is found that the effective screening length augments with the grain diameter d in addition to the granular column size. It is also revealed that λ exhibits stronger correlation with the bead diameter than that of the silo. This phenomenon is attributed to the reduced-shielding of the vertical stresses to the horizontal ones.

关键词： granular systems granular solids static sand piles granular compaction

Detecting abrupt change in land cover in the eastern Hindu Kush region using Landsat time series(1988-2020)

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Journal of Mountain Science 2022年第6期19卷 1699-1716页

作者： saeed A.khan Kim A.VANSELOW Oliver SASS Cyrus SAMIMI Department of Earth Sciences University of Bayreuth95447 BayreuthGermany Institute of Geography Friedrich-Alexander-University of Erlangen-Nürnberg91058 ErlangenGermany Bayreuth Centre of Ecology and Environmental Research University of Bayreuth95448 BayreuthGermany

Land cover change in the semi-arid environment of the eastern Hindu Kush region is driven by anthropogenic activities and environmental change impacts. Natural hazards, such as floods presumably influenced by climatic change, cause abrupt change of land cover. So far, little research has been conducted to investigate the spatiotemporal aspects of this abrupt change in the valleys. In order to explore the abrupt change in land cover and floods as its possible drivers in the eastern Hindu Kush, a semi-arid mountain region characterized by complex terrain, vegetation variation, and precipitation seasonality, we analyzed long-term Landsat image time series from 1988 to 2020 using Breaks For Additive Seasonal and Trend(BFAST). Overall, BFAST effectively detected abrupt change by using Landsat-derived Modified Soil Adjusted Vegetation Index(MSAVI). The results of our study indicate that approximately 95% of the study area experienced at least one abrupt change during 1988-2020. The years 1991, 1995, 1998, 2007, and 2016 were detected as the peak years, with the peaks occurring in different seasons. The annual trend of abrupt change is decreasing for the study area. The seasonality of abrupt change at the catchment level shows an increasing trend in the spring season for the southern catchments of Panjkora and Swat. The spatial distribution patterns show that abrupt change is primarily concentrated in the floodplains indicating that flooding is the primary driver of the land cover change in the region. We also demonstrated the accurate detection of past flood events(2015) based on the two case examples of Ayun, Rumbur, and Kalash valleys. The detection of the flood events was verified by fieldwork and historical high-resolution Google Earth imagery. Finally, our study provides an example of applying Landsat time series in a dry mountain region to detect abrupt changes in land cover and analyze impact of natural hazards such as floods.

关键词： Land cover change Floods Natural hazards BFAST Chitral Pakistan

Proposal for pathogenesis-based treatment options to reduce calcium oxalate stone recurrence

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Asian Journal of Urology 2023年第3期10卷 246-257页

作者： saeed R.khan Benjamin K.Canales Department of Pathology Immunologyand Laboratory MedicineUniversity of FloridaGainesvilleFLUSA Department of Urology University of FloridaGainesvilleFLUSA

Objective:Prevalence of kidney stone disease continues to increase globally with recurrence rates between 30%and 50%despite technological and scientific *** in recurrence would improve patient outcomes and reduce cost and stone *** objective was to review results of experimental studies performed to determine the efficacy of readily available compounds that can be used to prevent ***: All relevant literature up to October 2020,listed in PubMed is ***: Clinical guidelines endorse the use of evidence-based medications,such as alkaline agents and thiazides,to reduce urinary mineral supersaturation and ***,there may be additional steps during stone pathogenesis where medications could moderate stone *** calcium oxalate stones grow attached to Randall’s plaques or *** of clinical and experimental studies suggest involvement of reactive oxygen species and oxidative stress in the formation of both the plaques and *** renin-angiotensin-aldosterone system(RAAS),nicotinamide adenine dinucleotide phosphate(NADPH)oxidase,mitochondria,and NOD-like receptor pyrin domain containing-3(NLRP3)inflammasome have all been implicated at specific steps during stone pathogenesis in animal ***: In addition to supersaturation-reducing therapies,the use of anti-oxidants,free radical scavengers,and inhibitors of NADPH oxidase,NLRP3 inflammasome,and RAAS may prove beneficial for stone *** such as statins and angiotensin converting enzyme inhibitors are already in use as therapeutics for hypertension and cardio-vascular disease and have previously shown to reduce calcium oxalate nephrolithiasis in *** clinical evidence for their use in stone prevention in humans is limited,experimental data support they be considered along with standard evidence-based medications and clinical expertise when patients are being counselled for stone prevention.

关键词： Kidney stones Calcium oxalate Inflammation Inflammasome Supersaturation Reactive oxygen species Oxidative stress

Highly efficient and stable electrooxidation of methanol and ethanol on 3D Pt catalyst by thermal decomposition of In2O3 nanoshells

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Journal of Energy Chemistry 2017年第1期26卷 193-199页

作者： Yuhang Xie Hulin Zhang Guang Yao saeed Ahmed khan Xiaojing Cui Min Gao Yuan Lin State Key Laboratory of Electronic Thin Film and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054SichuanChina Center for Information in Medicine University of Electronic Science and Technology of ChinaChengdu 610054SichuanChina The First Sub-Institute Nuclear Power Institute of ChinaChengdu 610041SichuanChina

In this paper In2O3nanoshells have been synthesized via a facile hydrothermal approach. The nanoshells can be completely cracked into pony-size nanocubes by annealing, which are then used as a support of Pt catalyst for methanol and ethanol electrocatalytic oxidation. The prepared In2O3and supported Pt catalysts (Pt/In2O3) were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), field effect scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) were carried out, indicating the excellent catalytic performance for alcohol electrooxidation can be achieved on Pt/In2O3nanocatalysts due to the multiple active sites, high conductivity and a mass of microchannels and micropores for reactant diffusions arising from 3D frame structures compared with that on the Pt/C catalysts. © 2016 Science Press

关键词： Alcohols Catalyst activity Catalysts Chronoamperometry Cyclic voltammetry Decomposition Electrocatalysis Electrochemical impedance spectroscopy Electron microscopy Electrooxidation Energy dispersive spectroscopy Ethanol High resolution transmission electron microscopy Methanol Nanoshells Nanostructured materials Nanostructures Platinum Scanning electron microscopy Transmission electron microscopy X ray diffraction X ray photoelectron spectroscopy X ray spectroscopy

MWCNTs based flexible and stretchable strain sensors

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Journal of Semiconductors 2017年第5期38卷 18-23页

作者： saeed Ahmed khan Min Gao Yuechang Zhu Zhuocheng Yan Yuan Lin State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China

Carbon nanotubes have potential applications in flexible and stretchable devices due to their remarkable electromechanical *** and stretchable strain sensors of multi-walled carbon nanotubes（MWCNTs）with aligned or random structures were fabricated on poly-dimethylsiloxane（PDMS） substrate with different *** was observed that the spraycoatedtechniquebased strain sensor fabricated on PDMS substrate showed higher sensitivity higher stretchability,better linearity and excellent longer time stability than the sensor fabricated with other methods presented in this *** scanning electron microscopy images indicated the spray coating technique can produce a better uniform and compact CNT network,which is the important role affecting the performance of CNT-based flexible strain sensors.

关键词： strain sensor stretchable sensor carbon nanotube arrays

Electronic and thermoelectric properties of YbMg_(2)X_(2)(X=P,As,Sb,Bi)zintl compounds by first-principles method

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Journal of Rare Earths 2024年第1期42卷 147-154,I0006页

作者： Sajid khan Dil Faraz khan R.Neffati Tariq Usman Muhammad Waqar Ahsraf Shamim khan saeed Ullah Jan G.Murtaza Department of Physics University of Science&Technology BannuBannu28100Pakistan Department of Physics Faculty of ScienceKing Khalid UniversityP.O.Box 9004AbhaSaudi Arabia Laboratoire de Physique de La Matiere Condensee Departement de PhysiqueFaculte des Sciences de TunisUniversite Tunis El ManarCampus Universitaire1060TunisTunisia Department of Physics Shaoxing UniversityShaoxing312000China Department of Mathematics&Natural Sciences Prince Mohammad Bin Fahd UniversityAlkhobar31952Saudi Arabia Materials Modeling Lab Department of PhysicsIslamia College Peshawar25120KhyberPakhtunkhwaPakistan

In this work the structural,electronic and thermoelectric properties of YbMg_(2)X_(2)(X=P,As,Sb,Bi)zintl compounds were investigated comprehensively using first principles *** electronic properties were studied using PBE GGA,TB-mBJ and hybrid(YS-PBE0)*** the structural parameters of optimized structures are in harmonious agreement to the available *** band structure study illustrates that the titled materials manifest metallic and semi metallic nature using PBE and TB-mBJ potentials while they show wide band gap semiconducting behavior by following hybrid(YS-PBE0)*** density of states(TDOS)and partial density of states(PDOS)were also calculated to glimpse the contribution of orbitals of atoms in the formation of *** properties were studied by using BoltzTraP2 code employed to *** get enormous values of Seebeck coefficient(S),power factor(PF)and thermoelectric figure of merit(ZT)for all the samples YbMg_(2)X_(2)(X=P,As,Sb,Bi),Moreover,the overwhelming transport properties for the titled compounds indicate the optimum level of carriers’concentration which pinpoints these materials to be better thermoelectrics in the 1-2-2 zintl family.

关键词： Zintl compounds Hybrid functional Band structure Thermoelectrics Rare earths

A Hybrid and Lightweight Device-to-Server Authentication Technique for the Internet of Things

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Computers, Materials & Continua 2024年第3期78卷 3805-3823页

作者： Shaha Al-Otaibi Rahim khan Hashim Ali Aftab Ahmed khan Amir saeed Jehad Ali Department of Information Systems College of Computer and Information SciencesPrincess Nourah bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia Department of Computer Science Abdul Wali Khan University MardanMardan23200Pakistan Department of Computer Science and IT UET PeshawarJalozai Campus PeshawarPeshawar24240Pakistan Department of AI Convergence Network Ajou UniversitySuwon16499South Korea

The Internet of Things(IoT)is a smart networking infrastructure of physical devices,i.e.,things,that are embedded with sensors,actuators,software,and other technologies,to connect and share data with the respective server *** IoTs are cornerstones in different application domains,the device’s authenticity,i.e.,of server(s)and ordinary devices,is the most crucial issue and must be resolved on a priority ***,various field-proven methodologies were presented to streamline the verification process of the communicating devices;however,location-aware authentication has not been reported as per our knowledge,which is a crucial metric,especially in scenarios where devices are *** paper presents a lightweight and location-aware device-to-server authentication technique where the device’s membership with the nearest server is subjected to its location information along with other ***,Media Access Control(MAC)address and Advance Encryption Scheme(AES)along with a secret shared key,i.e.,λ_(i) of 128 bits,have been utilized by Trusted Authority(TA)to generate MaskIDs,which are used instead of the original ID,for every device,i.e.,server and member,and are shared in the offline ***,TA shares a list of authentic devices,i.e.,server S_(j) and members C_(i),with every device in the IoT for the onward verification process,which is required to be executed before the initialization of the actual communication ***,every device should be located such that it lies within the coverage area of a server,and this location information is used in the authentication process.A thorough analytical analysis was carried out to check the susceptibility of the proposed and existing authentication approaches against well-known intruder attacks,i.e.,man-in-the-middle,masquerading,device,and server impersonations,etc.,especially in the IoT ***,proposed authentication and existing state-of-the-art approaches have been s

关键词： Internet of things authenticity security location communication

Tectonic evolution of structures in Southern Sindh Monocline,Indus Basin,Pakistan formed in multi-extensional tectonic episodes of Indian Plate

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Geodesy and Geodynamics 2018年第5期9卷 358-366页

作者： Shabeer Ahmed Sarfraz Hussain Solangi Muhammad saeed khan Jadoon Adeel Nazeer Centre for Pure and Applied Geology University of Sindh Oil and Gas Development Company Limited

There are a number of structures and structural styles found in extensional tectonic settings of the world,and it is a big challenge to study the evolution of these structures. Evolution of structures formed in extensional tectonic settings have been studied by researchers on different extensional basins of the world. Southern Sindh Monocline lies on the western corner of Indian Plate and the tectonic history of Indian plate has also experienced different extensional episodes, and its journey rifted from Gondwanaland to its final welding to Asia. The aim of this study is to figure out the evolution of structures in the subsurface of Southern Sindh Monocline, Pakistan using the seismic data interpretation and flattening of horizons approach. Structures within the subsurface of Southern Sindh Monocline have been characterized by different tectonic episodes of Indian plate while rifting from Gondwanaland, rifting from other plates at different geological times and to its collision with the Asia. Basic structures within study area are classified into nine types while the structural styles have been classified into six types as horst and grabens, dominos, crotch, synthetic and antithetic, negative and flashlight structural style. The structures within the study area revealed evidence for three major structural episodes which can be characterized as Episode 1: Structures associated with rifting of Indian plate from Gondwanaland during Late Jurassic to Early Cretaceous, Episode 2: Modification and reactivation of previous structures while Madagascar rifted from Indian Plate during the Middle Cretaceous and during Episode 3: Inversion and reactivation of structures occurred when Indian Plate collided with Asia during Early Eocene.

关键词： Tectonic evolution Episodes Structures Sindh Monocline Pakistan Indian plate Eurasian plate Seismic data

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巴基斯坦药师角色转变中的挑战（英文）

药学服务与研究 2016年第1期16卷 19-24页

作者： saeed Ahmad khan Mughal Qayum Sajid khan Sadozai Department of Pharmacy Kohat University of Science and Technology

巴基斯坦的药师教育体系经历了不同阶段的进化历程,最初是三年制的学士教育,并于1978年延长至四年。为了与国际标准接轨并提供药师更多的就业机会,2003年该学制被5年制的药学博士教育替代,但是设立博士项目的初衷并没有实现。在现实中... 详细信息

巴基斯坦的药师教育体系经历了不同阶段的进化历程,最初是三年制的学士教育,并于1978年延长至四年。为了与国际标准接轨并提供药师更多的就业机会,2003年该学制被5年制的药学博士教育替代,但是设立博士项目的初衷并没有实现。在现实中药师的角色转变依然面临诸多挑战。由于存在不专业的实践活动,药师没有被医疗护理团队接纳为一个不可或缺的成员。本文将揭示这些挑战,向相关部门提出建议,采取根本性的法律措施,消除药师在角色转变中的障碍,为巴基斯坦的病人提供富有成效的、有价值的服务。

关键词：药剂师巴基斯坦药学实践药学服务