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Reliability-based robust multi-obj ective optimization of a 5-DOF vehicle vibration model subjected to random road profiles

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Journal of Central South University 2017年第1期24卷 104-113页

作者： Abolfazl Khalkhali Morteza Sarmadi sina yousefi Automotive Simulation and Optimal Design Research Laboratory School of Automotive EngineeringIran University of Science&TechnologyTehran 16846-13114Iran

Ride and handling are two paramount factors in design and development of vehicle suspension systems. Conflicting trends in ride and handling characteristics propel engineers toward employing multi-objective optimization methods capable of providing the best trade-off designs compromising both criteria simultaneously. Although many studies have been performed on multi-objective optimization of vehicle suspension system, only a few of them have used probabilistic approaches considering effects of uncertainties in the design. However, it has been proved that optimum point obtained from deterministic optimization without taking into account the effects of uncertainties may lead to high-risk points instead of optimum ones. In this work, reliability-based robust multi-objective optimization of a 5 degree of freedom （5-DOF） vehicle suspension system is performed using method of non-dominated sorting genetic algorithm-II （NSGA-II） in conjunction with Monte Carlo simulation （MCS） to obtain best designs considering both comfort and handling. Road profile is modeled as a random function using power spectral density （PSD） which is in better accordance with reality. To accommodate the robust approach, the variance of all objective functions is also considered to be minimized. Also, to take into account the reliability criterion, a reliability-based constraint is considered in the optimization. A deterministic optimization has also been performed to compare the results with probabilistic study and some other deterministic studies in the literature. In addition, sensitivity analysis has been performed to reveal the effects of different design variables on objective functions. To introduce the best trade-off points from the obtained Pareto fronts, TOPSIS method has been employed. Results show that optimum design point obtained from probabilistic optimization in this work provides better performance while demonstrating very good reliability and robustness. However, other optimum poi

关键词： probabilistic optimization vehicle suspension deterministic optimization ride handling genetic algorithm

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Third-Order Optical Nonlinearity in Two-Dimensional Transition Metal Dichalcogenides

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Communications in Theoretical Physics 2018年第9期69卷 344-360页

作者： sina Khorasani School of Electrical Engineering Sharif University of Technology Tehran lran Ecole Polyteehnique F6d6rale de Lausanne CH-1015 Lausanne Switzerlan

We present a detailed calculation of the linear and nonlinear optical response of four types of monolayer twodimensional (2D) transition-metal dichalcogenides (TMDCs), having the formula MX2 with M=Mo, W and X=S, *** calculations are based on 6-band tight-binding model of TMDCs, and then performing a semi-classical perturbation analysis of response functions. We numerically calculate the linearχ(1)μν(-ω;ω) and nonlinear surface susceptibility tensorsχ(3)μνζη(-ωΣ;ωr,ωs,ωt) withωΣ=ωr+ωs+ωt. Both non-degenerate and degenerate cases are studied for thirdharmonic generation and nonlinear refractive index, respectively. Computational results obtained with no external fitting parameters are discussed regarding two recent reported experiments on Mo S2, and thus we can confirm the extraordinarily strong optical nonlinearity of TMDCs. As a possible application, we demonstrate generation of aπ/4-rotated squeezed state by means of nonlinear response of TMDCs, in a silica micro-disk resonator covered with the 2D material. Our proposed method will enable accurate calculations of nonlinear optical response, such as four-wave mixing and highharmonic generation in 2D materials and their heterostructures, thus enabling study of novel functionalities of 2D photonic integrated circuits.

关键词： 2D materials nonlinear optics transition metal dichalcogenides quantum optics

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Multiple failure function based fragility curves for structures equipped with TMD

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Earthquake Engineering and Engineering Vibration 2021年第2期20卷 471-482页

作者： sina Bakhshinezhad Mohtasham Mohebbi Faculty of Engineering University of Mohaghegh ArdabiliArdabilIran

This paper presents a procedure to develop fragility curves of structures equipped with TMD considering multiple failure *** failure criteria considered are maximum inter-story drift ratio as a safety criterion,maximum absolute acceleration as a convenience criterion and TMD stroke *** relationship between intensity measure and responses of the structure was assumed to follow the power-law model,and a regression analysis was used to estimate its properties.A nonlinear eight-story shear building subjected to near-fault earthquakes was used for the numerical *** curves using multiple and single failure functions for an uncontrolled structure and a structure equipped with optimal TMDs were *** analysis showed that using multiple failure functions led to increasing the fragility when compared with using the single failure function for both the uncontrolled and controlled ***,TMDs slightly reduced the seismic fragility and have the capability to improve the reliability of the ***,it was found that the fragility was significantly influenced by the values of the capacity thresholds of both the acceleration of the structure and TMD stroke length,which should be selected by considering the target performance and application of the structure and control device.

关键词： fragility curves multiple failure function passive control tuned mass dampers

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Time Operator in Relativistic Quantum Mechanics

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Communications in Theoretical Physics 2017年第7期67卷 35-38页

作者： sina Khorasani School of Electrical Engineering Sharif University of Technology Tehran Iran tcole Polytechnique Fdrale de Lausanne Lausanne CH-1015 Switzerland

It is first shown that the Dirac＇s equation in a relativistic frame could be modified to allow discrete time, in agreement to a recently published upper bound. Next, an exact self-adjoint 4 x 4 relativistic time operator for spin-l/2 particles is found and the time eigenstates for the non-relativistic case are obtained and discussed. Results confirm the quantum mechanical speculation that particles can indeed occupy negative energy levels with vanishingly sma/l but non- zero probablity, contrary to the general expectation from classical physics. Hence, Wolfgang Pauli＇s objection regarding the existence of a self-adjoint time operator is fully resolved. It is shown that using the time operator, a bosonic field referred here to as energons may be created, whose number state representations in non-relativistic momentum space can be explicitly found.

关键词： quantum mechanics special relativity foundations of quantum mechanics operator theory

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Comparison of shallow tunneling method with pile and rib method for construction of subway station in soft ground

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Frontiers of Structural and Civil Engineering 2022年第6期16卷 704-717页

作者： sina AMIRI Ali Naghi DEHGHAN Department of Mining Engineering Science and Research BranchIslamic Azad UniversityTehranIran

In the present study,a comparison between the new shallow tunneling method(STM)and the traditional pile and rib method(PRM)was conducted to excavate and construct subway stations in the geological conditions of ***,by selecting Station Z6 located in the Tehran Subway Line 6 as a case study,the construction process was analyzed by *** maximum ground settlement of 29.84 mm obtained from this method was related to the station axis,and it was within the allowable settlement limit of 30 *** acceptable agreement between the results of numerical modeling and instrumentation data indicated the confirmation and accuracy of the excavation and construction process of Station Z6 by *** the next stage,based on the numerical model validated by instrumentation data,the value of the ground surface settlement was investigated during the station excavation and construction by *** results obtained from STM showed a significant reduction in the ground surface settlement compared to *** maximum settlement obtained from STM was 6.09 mm as related to the front of the excavation ***,the sensitivity analysis results denoted that in addition to controlling the surface settlement by STM,it is possible to optimize some critical geometric parameters of the support system during the station excavation and construction.

关键词： shallow tunneling method pile and rib method ground surface settlement subway station construction numerical modeling

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Internet of things-based health monitoring system for early detection of cardiovascular events during COVID-19 pandemic

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World Journal of Clinical Cases 2022年第26期10卷 9207-9218页

作者： sina Dami Department of Computer Engineering West Tehran BranchIslamic Azad UniversityTehran ***Iran

The coronavirus disease 2019(COVID-19)has currently caused the mortality of millions of people around the *** from the direct mortality from the COVID-19,the indirect effects of the pandemic have also led to an increase in the mortality rate of other non-COVID *** indicates that novel COVID-19 pandemic has caused an inflation in acute cardiovascular mortality,which did not relate to COVID-19 *** has in fact increased the risk of death in cardiovascular disease(CVD)*** this purpose,it is dramatically inevitable to monitor CVD patients’vital signs and to detect abnormal events before the occurrence of any critical conditions resulted in *** of things(IoT)and health monitoring sensors have improved the medical care systems by enabling latency-sensitive surveillance and computing of large amounts of patients’*** major challenge being faced currently in this problem is its limited scalability and late detection of cardiovascular events in IoT-based computing *** this end,this paper proposes a novel framework to early detection of cardiovascular events based on a deep learning architecture in IoT *** results showed that the proposed method was able to detect cardiovascular events with better performance(95.30%average sensitivity and 95.94%mean prediction values).

关键词： Health monitoring Early detection Cardiovascular events COVID-19 Pandemic Internet of things

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Stability analysis of the fluttering and autorotation of flow-induced rotation of a hinged flat plate

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Journal of Hydrodynamics 2013年第5期25卷 755-762页

作者： MIRZAEISEFAT sina FERNANDES Antonio Carlos Department of Naval Architecture and Marine Engineering University of Michigan COPPE/UFRJ Federal University of Rio de Janeiro

This work describes investigations performed on the interaction of uniform current and freely rotating plate about a fixed vertical axis. Fluttering and autorotation are two different motions that may occur during the flow induced rotation. The dimensional analysis proves that the motion in flow induced rotation motion is governed essentially by the dimensionless moment of inertia and Reynolds number. Certain combinations define the stability boundaries between fluttering and autorotation. Fluttering is oscillation of body about a vertical axis and the autorotation is a name given to the case when the body turns continuously about the vertical axis First, the loads and moment coefficients are calculated by experiments and streamline theory for different angles of attack for a fixed fiat plate. Then for dynamic case, a bifurcation diagram is presented based on experiments to classify different motion states of flow induced rotation. Finally, a dynamical model is proposed for stability analysis of flow induced rotation of a flat plate.

关键词： flow-induced rotation autorotation fluttering stability analysis

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Mapping Natural Hazard Impacts on Road Infrastructure——The Extreme Precipitation in Baden-Württemberg, Germany, June 2013

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International Journal of Disaster Risk Science 2014年第3期5卷 227-241页

作者： sina Keller Andreas Atzl Institute of Regional Science/Institute of Urban and Regional Planning Karlsruhe Institute of TechnologyKaiserstraße 1276131 KarlsruheGermany

Infrastructures in Europe have been affected by impacts of extreme natural events with increasing frequency over the past decades. One of the most recent examples is the flooding that affected parts of Germany in June 2013. Global warming is expected to change patterns of climate-related extreme events affecting *** article presents an explanatory approach. Based on an observational design, causal connections between the occurrence and patterns of extreme events and related road infrastructure impacts are analyzed. The hazard mapping case study in the state of Baden-Wrttemberg combines traffic information and data on the June 2013 extreme precipitation in Germany. It examines the precipitation occurrence and road infrastructure impact characteristics in Baden-Wu¨ rttemberg and identifies spatiotemporal hazard patterns. The article suggests further research needs and fields of application for risk mapping in climate change adaptation research in Germany.

关键词： Extreme precipitation Floods Germany Hazard patterns Landslides Road infrastructure

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Effect of Silica Fume on Compressive Strength of Oil-Polluted Concrete in Different Marine Environments

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China Ocean Engineering 2017年第6期31卷 716-723页

作者： Hamid SHAHRABADI sina SAYAREH Hamed SARKARDEH Department of Civil Engineering Chabahar Maritime UniversityChabaharIran Department of Civil Engineering University of Sistan&BaluchestanZahedanIran Department of Civil Engineering Faculty of EngineeringHakim Sabzevari UniversitySabzevarIran

In the present research, effect of silica fume as an additive and oil polluted sands as aggregates on compressive strength of concrete were investigated experimentally. The amount ofoil in the designed mixtures was assumed to be constant and equal to 2% of the sand weight. Silica fume accounting for 10%, 15% and 20% of the weight is added to the designed mixture. After preparation and curing, concrete specimens were placed into the three different conditions： fresh, brackish and saltwater environments （submerged in fresh water, alternation of exposed in air ＆ submerged in sea water and submerged in sea water）. The result of compressive strength tests shows that the compressive strength of the specimens consisting of silica fume increases significantly in comparison with the control specimens in all three environments. The compressive strength of the concrete with 15% silica fume content was about 30% to 50% higher than that of control specimens in all tested environments under the condition of using polluted aggregates in the designed mixture.

关键词： compressive strength water environments oil polluted sands silica fume marine concrete structures

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Estimation of pore volumes to breakthrough number in limestone cores by derivation of an empirical model

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Petroleum Research 2021年第3期6卷 264-270页

作者： sina Lohrasb Radzuan Junin Department of Petroleum Engineering School of Chemical and Energy EngineeringFaculty of EngineeringUniversiti Teknologi MalaysiaUTM81310Johor BahruMalaysia Institute for Oil and Gas Universiti Teknologi Malaysia81310Johor BahruMalaysia

Acidizing in carbonate formations is an inevitable stimulation treatment method for oil and gas *** the limestone,acidizing stimulation makes capillary wormholes to increase fluids flow reservoir pro*** pore volume to breakthrough number is one of the main indexes for recognizing the wormhole ***,finding the pore volume to breakthrough number is one of the main goals in the limestone *** this number is always required for experimental works,which needs time,energy and *** purpose of this research is to develop an empirical method to estimate an acceptable result for this number merely by implementing limestone core and acid properties without any experimental *** order to create a wormhole,an empirical method is developed using the law of conservation of mass considering that the core of limestone as an isolated package and the overall mass is constant in this package in the acidizing ***,to develop the mathematical section,the Damk€ohler number is *** this number must be calculated experimentally,a constant number is created in the model to eliminate the Damkohler *** average accuracy of 92.31%is obtained for the developed empirical model by comparing the results obtained from the other three experimental and numerical *** study conclusively provides a thoroughly empirical method for estimating a high accuracy of the pore volume to breakthrough number by only using known physical properties limestone core and acid.

关键词： Acidizing Pore volumes to breakthrough Limestone Wormhole Empirical model

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