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Chemical Research in Chinese Universities 2015年第5期31卷 693-698页

作者： SAMI Soukrata MOHAMED Belhouchet tahar mhiri Laboratory of Solid State Faculty of Sciences University of Sfax 3000 Sfax Tunisia

A title organic-inorganic hybrid material 2-amino-3-benzyloxy pyridinium perchlorate was synthesized by slow evaporation at room temperature using 2-amino-3-benzyloxypyridine as the structure-directing agent. The structure of the title compound was determined by means of single-crystal X-ray diffraction at 293 K. The results show that this compound crystallizes in the centrosymetric monoclinic system with a space group of P2 1/n and lattice parameters of a=0.7025（5） nm, b=1.2635（5） nm, c=1.5766（5） nm, Z=4 and V=1.3905（2） nm^3. The crystal structure has been determined and refined to R1=0.0367 and wR2=0.1022 using 2326 independent reflections and can be described as a succession of organic and inorganic layers parallel to the bc plane. In this arrangement, hydrogen bonds and van der Waals interactions between different species play an important role in the two-dimensional（2D） network cohesion. This compound was also characterized by means of infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis-differential thermal analysis（TG-DTA）. Moreover, protonic conduction of this compound determined by an impedance analyzer has been studied in the temperature range of 303--373 K.

关键词： Organic-inorganic hybrid Chemical synthesis Infrared and Raman spectroscopy Thermal analysis Electrical property

Crystal Structure, Thermal Behaviour and Vibrational Spectra of Tetraethylammonium Dihydrogenmonophosphate Bis Phosphoric Acid

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Crystal Structure Theory and Applications 2013年第1期2卷 8-15页

作者： Ikram Dhouib Salih Al-Juaid tahar mhiri Zakaria Elaoud Chemistry Department Faculty of Science King Abdulaziz University Jeddah KSA Laboratoire de l’Etat Solide Département de Chimie Faculté des Sciences de Sfax Sfax Tunisia

Single crystals of the tetraethylammonium dihydrogenmonophosphate bis trihydrogenmonophosphate [CH3CH2]4N+(H2PO4)(H3PO4)2(TEP), were grown by slow evaporation solution technique at room temperature. The compound was characterised by IR, Raman, differential thermal analysis (TG-DTA) and single crystal X-ray diffraction. It crystallizes in the monoclinic system (space group P21/c) with the following unit cell dimensions: a = 7.765 (2) , b = 16.531 (4) , c = 14.843 (2) , β = 100.99 (2)o, Z=4 , DX =1.67Mg.m-3, Dm=1.532Mg-3, λ (MoKa) = 0.71073 , u=0.384 mm-1, F(000)=991, T = 20 (2)o. The structure was solved by the direct method and refined to final R value of 0.0342 and Rw=0.107 for 3239 independent [(CH3CH2)4N]+ reflections. The structure consists of infinite parallel two-dimensional planes built of mutually , H3PO4 tetrahedra ?and cations connected by strong and hydrogen bonding. There are no contacts other than van der Waals interactions between the layers.

关键词： Organic Phosphate Crystalline Structure Vibrational Spectra Thermal Behaviour Differential Thermal Analysis

Edge-Enabled Metaverse:The Convergence of Metaverseand Mobile Edge Computing

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Tsinghua Science and Technology 2024年第3期29卷 795-805页

作者： Nyothiri Aung Sahraoui Dhelim Liming Chen Huansheng Ning Luigi Atzori tahar Kechadi Information Engineering College Xinjiang Institute of EngineeringUrumqi 830023Chinaand also with School of Computer ScienceUniversity College DublinDublinD04 V1W8Ireland School of Computing Ulster UniversityBelfastBT151EDUK School of Computer and Communication Engineering University of Science and Technology BeijingBeijing 100083China Department of Electrical and Electronic Engineering University of CagliariSardinia 09124Italy School of Computer Science University College DublinDublinD04 V1W8Ireland

Metaverse is a virtual environment where users are represented by their avatars to navigate a virtual world having strong links with its physical *** state-of-the-art Metaverse architectures rely on a cloud-based approach for avatar physics emulation and graphics rendering *** current centralized architecture of such systems is unfavorable as it suffers from several drawbacks caused by the long latency of cloud access,such as low-quality *** this end,we propose a Fog-Edge hybrid computing architecture for Metaverse applications that leverage an edge-enabled distributed computing *** applications leverage edge devices’computing power to perform the required computations for heavy tasks,such as collision detection in the virtual universe and high-computational 3D physics in virtual *** computational costs of a Metaverse entity,such as collision detection or physics emulation,are performed at the device of the associated physical *** validate the effectiveness of the proposed architecture,we simulate a distributed social Metaverse *** simulation results show that the proposed architecture can reduce the latency by 50%when compared with cloud-based Metaverse applications.

关键词： industrial Metaverse edge computing Blockchain virtual environment task offloading fog computing

Topology reduction through machine learning to accelerate dynamic simulation of district heating

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Energy and AI 2024年第3期17卷 247-260页

作者： Dubon Rodrigue Mohamed tahar Mabrouk Bastien Pasdeloup Patrick Meyer Bruno Lacarrière IMT Atlantique GEPEAUMR CNRS 61444 rue Alfred KastlerNantesF-44307France IMT Atlantique Lab-STICCUMR CNRS 6285655 Av.du TechnopoleBrestF-29238France

District heating networks (DHNs) provide an efficient heat distribution solution in urban areas, accomplished through interconnected and insulated pipes linking local heat sources to local consumers. This efficiency is further enhanced by the capacity of these networks to integrate renewable heat sources and thermal storage systems. However, integration of these systems adds complexity to the physical dynamics of the network, necessitating complex dynamic simulation models. These dynamic physical simulations are computationally expensive, limiting their adoption, particularly in large-scale networks. To address this challenge, we propose a methodology utilizing Artificial Neural Networks (ANNs) to reduce the computational time associated with the DHNs dynamic simulations. Our approach consists in replacing predefined clusters of substations within the DHNs with trained surrogate ANNs models, effectively transforming these clusters into single nodes. This creates a hybrid simulation framework combining the predictions of the ANNs models with the accurate physical simulations of remaining substation nodes and pipes. We evaluate different architectures of Artificial Neural Network on diverse clusters from four synthetic DHNs with realistic heating demands. Results demonstrate that ANNs effectively learn cluster dynamics irrespective of topology or heating demand levels. Through our experiments, we achieved a 27% reduction in simulation time by replacing 39% of consumer nodes while maintaining acceptable accuracy in preserving the generated heat powers by sources.

关键词： District heating network Topology reduction Artificial neural networks Hybrid modeling Graph based formulation

Homogeneous tree height derivation from tree crown delineation using Seeded Region Growing(SRG)segmentation

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Geo-Spatial Information Science 2020年第3期23卷 195-208,I0001页

作者： Muhamad Farid Ramli Khairul Nizam tahar Centre of Studies for Surveying Science and Geomatics Faculty of Architecture Planning and SurveyingUniversiti Teknologi MARAShah AlamSelangorMalaysia

The demand for tree height derivation is increasing year by year,especially for large plantation and forest *** conventional method needs a long time to complete tree measurement for large forest area,especially when using a pole,measuring tape,rangefinder,clinometer,and tree *** study aims to evaluate the height of oil palm tree based on crown diameter by using a multi-rotor Unmanned Aerial Vehicle(UAV).Digital Elevation Model(DEM)and orthophoto were generated by using Agisoft software,while oil palm tree crown diameter was delineated by using seed generation with Quantum Geographic Information System(QGIS)and Seeded Region Growing(SRG)segmentation methods in the System for Automated Geoscientific Analysis(SAGA).The study validates the results between the actual tree height and tree height estimated from *** results showed that the orthophoto was successfully generated with a Ground Sampling Distance(GSD)of 2.95 cm and 129 tree crowns were successfully *** accuracy of the tree height as compared to the actual measurement was 57.7 *** conclusion,UAV images are capable of determining the tree height after going through the correct procedure to help foresters in their daily task.

关键词： Oil palm diameter validation accuracy Unmanned Aerial Vehicle(UAV)

Formally Analyzing Expected Time Complexity of Algorithms Using Theorem Proving

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Journal of Computer Science & Technology 2010年第6期25卷 1305-1320页

作者： Osman Hasan Sofiène tahar Department of Electrical and Computer Engineering Concordia University

Probabilistic techniques are widely used in the analysis of algorithms to estimate the computational complexity of algorithms or a computational ***,such analyses are performed using paper-and-pencil proofs and the results are sometimes validated using simulation *** techniques are informal and thus may result in an inaccurate *** this paper,we propose a formal technique for analyzing the expected time complexity of algorithms using higher-order-logic theorem *** approach calls for mathematically modeling the algorithm along with its inputs,using indicator random variables,in higher-order *** model is then used to formally reason about the expected time complexity of the underlying algorithm in a theorem *** paper includes the higher-order-logic formalization of indicator random variables,which are fundamental to the proposed *** order to illustrate the practical effiectiveness and utilization of the proposed infrastructure,the paper also includes the analysis of algorithms for three well-known problems,i.e.,the hat-check problem,the birthday paradox and the hiring problem.

关键词： formal method higher-order logic probability theory theorem proving birthday paradox hat-check problem hiring problem

ACOUSTIC ANALYSIS OF HYDRODYNAMIC AND ELASTO-HYDRODYNAMIC OIL LUBRICATED JOURNAL BEARINGS

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Journal of Hydrodynamics 2012年第2期24卷 250-256页

作者： BOUAZIZ Slim FAKHFAKH tahar HADDAR Mohamed Dynamic of Mechanical Systems Research Unit (UDSM) University of Sfax Mechanics Modelling and Production Research Unit (U2MP) and National School of Engineers of Sfax (ENIS) BP.11733038University of Sfax

The purpose of the present paper is to investigate the effect of elastic deformation of bearing liner on the acoustic behavior of oil lubricated journal *** is performed for hydrodynamic（HD） and elasto-hydrodynamic （EHD） *** behavior and acoustical properties are investigated through an analysis of pressure fluctuation calculated from the Reynolds equation governing the flow in the clearance space of the journal *** is solved numerically using the finite difference method with the successive over relaxation *** elasto-hydrodynamic lubrication,the finite element method with in iteration scheme is adopted to solve both Reynolds equation and the three-dimensional elasticity equation representing the displacement field in the bearing *** results show that the sound pressure level of the bearing is markedly influenced by the flexibility of the bearing liner,the viscosity of lubricant and the load applied to *** analysis shows that the journal centre＇s orbit,from a disturbed position,converges to the static equilibrium position faster than EHD *** results of the present paper could aid in the design of low-noise rotor-bearing systems supported by oil lubricated journal bearings.

关键词： vibration amplitude pressure level lubricated bearing sound pressure

Formal Reasoning About Finite-State Discrete-Time Markov Chains in HOL

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Journal of Computer Science & Technology 2013年第2期28卷 217-231页

作者： Liya Liu Osman Hasan Sofiène tahar Department of Electrical and Computer Engineering Concordia University

Markov chains are extensively used in modeling different aspects of engineering and scientific systems, such as performance of algorithms and reliability of systems. Different techniques have been developed for analyzing Markovian models, for example, Markov Chain Monte Carlo based simulation, Markov Analyzer, and more recently probabilistic model- checking. However, these techniques either do not guarantee accurate analysis or are not scalable. Higher-order-logic theorem proving is a formal method that has the ability to overcome the above mentioned limitations. However, it is not mature enough to handle all sorts of Markovian models. In this paper, we propose a formalization of Discrete-Time Markov Chain （DTMC） that facilitates formal reasoning about time-homogeneous finite-state discrete-time Markov chain. In particular, we provide a formal verification on some of its important properties, such as joint probabilities, Chapman-Kolmogorov equation, reversibility property, using higher-order logic. To demonstrate the usefulness of our work, we analyze two applications： a simplified binary communication channel and the Automatic Mail Quality Measurement protocol.

关键词： discrete-time Markov chain higher-order logic probability theory theorem prover

Reduction of vibration by periodically stitched sandwich panel

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Chinese Journal of Aeronautics 2021年第7期34卷 39-49页

作者： Nan LI Mabrouk BEN tahar Liang MENG Fusheng SUI Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China Sorbonne Universites Universitede Technologie de CompiegneCNRSUMR 7337 RobervalCentre de Recherche RoyallieuCS 60319Compiegne Cedex 60203France State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

This work reveals that the addition of periodically distributed stitches to sandwich structure enables a significant reduction of vibration in stop-band and this new functionality is systematically ***,a finite element model which is capable of taking into consideration the three layers of the sandwich as well as the stitches is *** diagram of dispersion is calculated by applying Floquet-Bloch theorem to the boundaries of unit *** properly chosen properties of stitches,a stop-band for flexural wave is *** stop-band is further confirmed by the forced response of a large stitched sandwich panel under point *** level of vibration in the stop-band is significantly *** influence of the stitch rigidity and density on upper and lower limits of stop-band is also examined,which confirms that stitched sandwich can be tuned to mitigate vibration in a certain frequency band with appropriate stitch *** investigations have demonstrated the potential application of stitched sandwich in the area of vibration reduction.

关键词： Composite structure Parametric study Periodic structures Reduction of vibration Stitched sandwich

Evaluating the impact of mass housings'in-between spaces'spatial configuration on users'social interaction

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Frontiers of Architectural Research 2020年第1期9卷 34-53页

作者： Wiem Zerouati tahar Bellal Habitat and Environment Laboratory Department of ArchitectureInstitute of Architecture and Earth SciencesFerhat Abbas University-Setif 1Setif 19000Algeria

This research examines the impact of in-between space configuration on users'social *** effects of different degrees of permeability of these spaces on the social interactions of the inhabitants are also *** research is based on a comparative approach using space syntax analysis and snapshot observations on four mass housing neighborhoods in Serif,*** neighborhoods are selected according to their degree of permeability,location in the city,realization period,and syntax measures from integrated to *** activity patterns of two-week days for each study case are observed and *** results of observed social activities and syntactic measures demonstrate that spatial configuration affects people's use of in-between ***,connectivity and clustering coefficients are revealed to be important indicators of social *** urban studies argued that integrated spaces are mostly used by ***,social interaction in the studied cases increases in the least connected areas,adjoining spaces to the buildings,and most closed *** research finds that social activities are dependent on the degree of permeability,which when low,gives rise to increased social interaction and activities.

关键词： In-between spaces Social interaction Degree of permeability Space syntax Snapshot observation