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Advances in fibre optic based geotechnical monitoring systems for underground excavations

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International Journal of Mining science and Technology 2019年第2期29卷 229-238页

作者： Hongkui Gong Mehmet s.Kizil Zhongwei Chen Moe Amanzadeh ben Yang saiied M.Aminossadati school of Mechanical and Mining Engineering The University of Queensland

Geotechnical stability is a major concern for the long-term safety and integrity of underground infrastructures such as tunnels, railway stations, mine shafts and hydraulic power chambers. An effective geotechnical monitoring system is able to provide adequate warning to underground personnel prior to any unexpected major geotechnical failure. This paper reviews the conventional geotechnical monitoring sensors and the emerging Fibre Optic sensing(FOs) techniques, pointing out their unique features and major differences. Recent advances in various FOs based monitoring systems, including Brillouin time domain distributed optical sensors and fibre Bragg grating(FBG) sensors, are investigated through a critical review of the laboratory studies and field applications used for underground geotechnical monitoring. Particular emphasis is given to fibre packaging, temperature compensation, installation methods and instrumentation performance in the underground environment. A detailed discussion of the advantages and limitations of each FOs monitoring system is also presented in this paper.

关键词： Underground geotechnical monitoring Conventional geotechnical instruments Distributed optical fibre sensors Fibre Bragg grating Brillouin optical analysis

Comparison of Constant and Time-variant Optimal Forcing Approaches in El Nio simulations by Using the Zebiak–Cane Model

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Advances in Atmospheric sciences 2016年第6期33卷 685-694页

作者： ben TIAN Wansuo DUAN Laboratory for Climate studies National Climate CenterChina Meteorological AdministrationBeijing 100081 state Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029

Model errors offset by constant and time-variant optimal forcing vector approaches （termed COF and OFV, respectively） are analyzed within the framework of E1 Nifio simulations. Applying the COF and OFV approaches to the well-known Zebiak-Cane model, we re-simulate the 1997 and 2004 E1 Nifio events, both of which were poorly degraded by a certain amount of model error when the initial anomalies were generated by coupling the observed wind forcing to an ocean com- ponent. It is found that the Zebiak-Cane model with the COF approach roughly reproduced the 1997 E1 Nifio, but the 2004 E1 Nifio simulated by this approach defied an ENsO classification, i.e., it was hardly distinguishable as CP-E1 Nifio or EP-E1 Nifio. In hoth E1 Nifio simulations, substituting the COF with the OFV improved the fit between the simulations and obser- vations because the OFV better manages the time-variant errors in the model. Furthermore, the OFV approach effectively corrected the modeled E1 Nifio events even when the observational data （and hence the computational time） were reduced. such a cost-effective offset of model errors suggests a role for the OFV approach in complicated CGCMs.

关键词： ENsO simulation model error optimal forcing vector

Diagnosing ssT Error Growth during ENsO Developing Phase in the BCC_CsM1.1(m) Prediction system

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Advances in Atmospheric sciences 2022年第3期39卷 427-442页

作者： ben TIAN Hong-Li REN Laboratory for Climate studies&CMA-NJU Joint Laboratory for Climate Prediction studies National Climate CenterChina Meteorological AdministrationBeijing 100081China state Key Laboratory of severe Weather Institute of Tibetan Plateau&Polar MeteorologyChinese Academy of Meteorological SciencesBeijing 100081China Department of Atmospheric science School of Environmental StudiesChina University of GeoscienceWuhan 430074China

In this study, the predictability of the El Nino-south Oscillation(ENsO) in an operational prediction model from the perspective of initial errors is diagnosed using the seasonal hindcasts of the Beijing Climate Center system Model,BCC;sM1.1(m). Forecast skills during the different ENsO phases are analyzed and it is shown that the ENsO forecasts appear to be more challenging during the developing phase, compared to the decay phase. During ENsO development, the ssT prediction errors are significantly negative and cover a large area in the central and eastern tropical Pacific, thus limiting the model skill in predicting the intensity of El Nino. The large-scale ssT errors, at their early stage, are generated gradually in terms of negative anomalies in the subsurface ocean temperature over the central-western equatorial Pacific,featuring an error evolutionary process similar to that of El Nino decay and the transition to the La Nina growth ***, for short lead-time ENsO predictions, the initial wind errors begin to play an increasing role, particularly in linking with the subsurface heat content errors in the central-western Pacific. By comparing the multiple samples of initial fields in the model, it is clearly found that poor ssT predictions of the Nino-3.4 region are largely due to contributions of the initial errors in certain specific locations in the tropical Pacific. This demonstrates that those sensitive areas for initial fields in ENsO prediction are fairly consistent in both previous ideal experiments and our operational predictions,indicating the need for targeted observations to further improve operational forecasts of ENsO.

关键词： ENsO prediction initial errors error evolution ssT

symmetries and conservation laws associated with a hyperbolic mean curvature flow

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Applied Mathematics(A Journal of Chinese Universities) 2022年第4期37卷 583-597页

作者： GAO ben YIN Qing-lian College of Mathematics Taiyuan University of TechnologyTaiyuan 030024China

Under investigation in this paper is a hyperbolic mean curvature flow for convex evolving ***,in view of Lie group analysis,infinitesimal generators,symmetry groups and an optimal system of symmetries of the considered hyperbolic mean curvature flow are *** the same time,some group invariant solutions are computed through reduced *** particular,we construct explicit solutions by applying the power series ***,the convergence of the solutions of power series is ***,conservation laws of the hyperbolic mean curvature flow are established via Ibragimov's approach.

关键词： hyperbolic mean curvature flow symmetries power series solutions conservation laws

An Efficient HW/sW Design for Text Extraction from Complex Color Image

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Computers, Materials & Continua 2022年第6期71卷 5963-5977页

作者： Mohamed Amin ben Atitallah Rostom Kachouri Ahmed ben Atitallah Hassene Mnif LETI(E.N.I.s.) University of SfaxSfaxTunisia Laboratory of informatics Gaspard-MongeA3SIESIEE ParisCNRSGustave Eiffel UniversityFrance National Engineering school of Gabes(ENIG) University of GabesTunisia Department of Electrical Engineering Jouf UniversitySakakaAljoufSaudi Arabia

In the context of constructing an embedded system to help visually impaired people to interpret text,in this paper,an efficient High-level synthesis(HLs)Hardware/software(HW/sW)design for text extraction using the Gamma Correction Method(GCM)is ***,the GCM is a common method used to extract text from a complex color image and *** purpose of this work is to study the complexity of the GCM method on Xilinx ZCU102 FPGA board and to propose a HW implementation as Intellectual Property(IP)block of the critical blocks in this method using HLs flow with taking account the quality of the text *** IP is integrated and connected to the ARM Cortex-A53 as coprocessor in HW/sW codesign *** experimental results show that theHLs HW/sW implementation of the GCM method on ZCU102 FPGA board allows a reduction in processing time by about 89%compared to the sW *** result is given for the same potency and strength of sW implementation for the text extraction.

关键词： Text extraction GCM HW/sW codesign FPGA HLs flow

Nonlinear unknown input observer using mean value theorem and genetic algorithm

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International Journal of Modeling, simulation, and scientific Computing 2019年第2期10卷 42-63页

作者： Ramzi ben Messaoud Laboratoire de Nanomateriaux et des systemes Pour les Energies Renouvelables Centre de Recherches et des Technologies de l’Energie BP.95 Hammam Lif 2050Tunisia

In this note,we consider a new unknown input observer design for nonlinear *** main idea consists in determining the estimation error and mean value theorem parameters(β)to introduce them into proposed observer *** process is designed on the basis of mean value theorem and genetic *** stability study relies on the use of a classical quadratic Lyapunov *** observer’s gains are determined *** the validation of theoretical development proposed in this paper,we consider two practical realizations that deals with the secure communication problem.

关键词： Genetic algorithm unknown input observer nonlinear system mean value theorem state estimation

Energy efficient downlink MIMO transmission with linear precoding

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science China(Information sciences) 2013年第2期56卷 90-101页

作者： XU Jie LI shiChao QIU Ling sLIMANE ben s. YU ChengWen Department of Electronic Engineering and Information science University of Science and Technology of China Department of Communication systems (Cos) ICT The Royal Institute of Technology (KTH) Wireless Research Huawei Technologies Company Limited

Energy efficiency (EE) is becoming increasingly important for wireless cellular networks. This paper addresses EE optimization problems in downlink multiuser MIMO systems with linear precoding. Referring to different active transmit/receive antenna sets and transmission schemes as different modes, we propose a joint bandwidth/power optimization and mode switching scheme to maximize EE. With a specific mode, we prove that the optimal bandwidth and transmit power is either full transmit power or full bandwidth. After deriving the optimal bandwidth and transmit power, we further propose mode switching to select the mode with optimal EE. since the optimal mode switching, i.e. exhaustive search, is too complex to implement, an alternative heuristic method is developed to decrease the complexity through reducing the search size and avoiding the EE calculation during each search. Through simulations, we demonstrate that the proposed methods can significantly improve EE and the performance is similar to the optimal exhaustive search.

关键词： energy efficiency downlink multiuser MIMO linear precoding bandwidth/power optimization mode switching low complexity

Automatic Fall Detection Using Membership Based Histogram Descriptors

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Journal of Computer science & Technology 2017年第2期32卷 356-367页

作者： Mohamed Maher ben Ismail Ouiem Bchir College of Computer and Information sciences King Saud University Riyadh 11495 KSA

t We propose a framework for automatic fall detection based on video visual feature extraction. The proposed approach relies on a membership histogram descriptor that encodes the visual properties of the video frames. This descriptor is obtained by mapping the original low-level visual features to a more discriminative descriptor using possibilistic memberships. This mapping can be summarized in two main phases. The first one consists in categorizing the low-level visual features of the video frames arid generating homogeneous clusters in an unsupervised way. The second phase uses the obtained membership degrees generated by the clustering process to compute the membership based histogram descriptor （MHD）. For the testing stage, the proposed fall detection approach categorizes unlabeled videos as ＂Fall＂ or ＂Non-Fall＂ scene using a possibilistic K-nearest neighbors classifier. The proposed approach is assessed using standard videos dataset that simulates patient fall. Also, we compare its performance with that of state-of-the-art fall detection techniques.

关键词： fall detection possibilistic approach feature extraction clustering

Mapping land subsidence over the eastern Beijing city using satellite radar interferometry

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International Journal of Digital Earth 2018年第5期11卷 504-519页

作者： Zheyuan Du Linlin Ge Alex hay-Man Ng Li Xiaojing Liyuan Li Geoscience and Earth Observing system Group(GEOs) School of Civil and Environmental EngineeringUNSW AustraliaSydneyAustralia Department of surveying Engineering Guangdong University of TechnologyGuangzhouPeople’s Republic of China

Beijing City has suffered from groundwater-induced subsidence since the late 1930s and the over-exploration of groundwater could lead to subsidence as much as−12.0 cm yr−*** studies on the ground deformation at Beijing City mainly focused on the period before the year of 2014 when a mega-engineering project was launched to reduce water shortage in *** study the most recent ground deformation,19 L-band ALOs-1 PALsAR images(June 2007–January 2011),24 C-band sentinel-1 sAR images(June 2015–November 2016)together with 9 ALOs-2 PALsAR acquisitions(september 2014–February 2017)were analysed in this *** measurements were exploited to verify the ALOs-1-based time series InsAR(Ts-InsAR)result while sentinel-1 and ALOs-2 result were cross-verified with each ***,the whole study area was divided into four sub-zones,and the result indicated that the subsidence rates over five townships,Cuigezhuan,Jinzhan,Liyuan,songzhuang and Yanjiao were accelerating and more attentions should be *** the contrary,the town centre of Douge Zhuang township experienced a decreasing trend between these two ***,the time series measurements with respect to five selected measurement points and the profile line along the subsidence hot spots were analysed.

关键词： subsidence Beijing groundwater sAR interferometry