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Efficiency of the motion amplification device with viscous dampers and its application in high-rise buildings

Earthquake Engineering and Engineering Vibration 2009年第4期8卷 521-536页

作者： Henry C.Huang wsp Asia Ltd.

After nearly a decade of application and investigation, a motion amplification device with viscous dampers for energy dissipation has been recognized as an effective solution to mitigate wind or seismic excitation, especially for stiff structural systems. As a result of compensation of amplified motion, it has been proved that the efficiency of viscous damper largely depends on the motion amplification device configuration, particularly for device stiflhess. In this paper, a ＂scissor-jack＂ type of motion amplification device, called a ＂toggle brace damper＂ system, is studied. It is demonstrated that the efficiency of such a device reflected by its amplification factor is not merely a function of its geometric configuration, but is highly dependent on the support elements＇ stiffness as well, similar to the mechanism of a leverage arm. Accordingly, a mathematical model in terms of complex modulus of the viscous damper with consideration of the support brace＇s stiffness is established. The results indicate that the efficiency of the motion amplification device with viscous dampers significantly depends on the stiffness of the support elements. Other parameters, such as toggle brace configuration and damping values of the viscous damper, are studied and compared. As an application example, numerical analyses are conducted to study the dynamic performance of a 39-story office tower installed with toggle brace dampers constructed on soft soil in a reclaimed area, under a combined effect of the vortex shedding of an adjacent existing 52-story building and earthquakes. The results show that viscous dampers with a motion amplification system using a properly designed toggle brace device proved to be an effective solution to alleviate the external excitations.

关键词： motion amplification device vibration mitigation viscous damper energy dissipation toggle brace damper

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Innovative roadside design curve of lateral clearance： Roadway reverse horizontal curves

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Journal of Traffic and Transportation Engineering(English Edition) 2018年第4期5卷 268-283页

作者： Qing Chong You Said M. Easa wsp canada inc. Thornhill Ontario L3T OA1 Canada Department of Civil Engineering Ryerson University Toronto Ontario M5B 2K3 Canada

This paper presents a proposed concept of a spiraled roadside curve for determining the required lateral clearance that satisfies sight distance needs on a roadway reverse hori- zontal curve. The spiraled roadside curve was evaluated in the context of roadway plan view. The characteristics of its corresponding lateral offsets were analyzed. It was found that the ratio of the radii for the two reversing circular curves was the major factor that impacted the ratio of the required offset to the maximum offset of a circular curve. A single design chart and a design table were developed. The required offsets at alignment reversing sections were far less than those recommended by the American Association of State Highways and Transportation Officials （AASHTO） and those required at the approach and departure sections of a roadway simple curve. At the common point of the two reversing circular curves having a radius ratio R2/R1 ranging from 0.5 to 2, the required offsets were approximately 34%-66% of the maximum offsets recommended by AASHTO and approximately 41%-79% of those required in the case of a simple curve. The engi- neering implications of the proposed spiraled roadside curve are multifold：（a） it can be designed in a way similar to traditional roadway design, （b） it avoided the application of numerous design charts and extensive computations, （c） it can be easily staked on the field, （d） it not only greatly improved the A_ASHTO approximate approach, but also improved roadway design consistency.

关键词： Roadside curve Lateral clearance Reverse curves Offset

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Relationship between rock macro-and micro-properties and wellbore breakout type

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Underground Space 2021年第1期6卷 62-75页

作者： Hossein Rahmati Alireza Nouri Dave Chan Hans Vaziri University of Alberta AlbertaCanada BP America inc. HoustonUSA

This study numerically investigates the effect of material micro-and macro-parameters on the failure mechanisms and geometry of a wellbore *** analysis of the borehole breakout is essential in addressing wellbore stability,well completion,and sand production *** three-dimensional discrete element method(DEM)was used in the *** numerical tool was used in numerical model simulations of drilling through sandstone in cubic samples at the laboratory scale subjected to pre-existing far-field ***,a series of triaxial testing simulations were performed to relate the micromechanical parameters to the macromechanical material *** results showed that the geometry of the breakout is affected,among the material micro-parameters,by the particle contact modulus,bond normal and shear strengths,particle crushing strength,and particle size ***,it was found that the macro-parameters inc.uding Young’s modulus,friction and dilation angles,and uniaxial compression strength(UCS)also affect the type of breakout.

关键词： Borehole breakout Numerical simulation Material properties

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An Analytical Model Based on the Theory of Constant Heat Flux Ratio Across the Frozen Layer for Solving Planar, Cylindrical and Spherical Freezing Problems

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Journal of Thermal Science 2004年第2期13卷 155-162页

作者： Sui Lin Zheng Jiang Department of Mechanical and Industrial Engineering Concordia University Montreal Canada Flomerics inc. Southborough USA

The purpose of the paper is to establish a theory of the constant heat flux ratio across the frozen layer based on the dimensional analysis of the system equations describing the freezing processes. An analytical model is then developed, utilizing this theory, for solving the planar, cylindrical and spherical freezing problems with both inward and outward freezing. As there is no exact solution available for the cylindrical and spherical freezing processes, the temperature distribution in the planar solidification obtained from the model is compared with the exact solution. They are in excellent agreement. For the cylindrical and spherical freezing, the complete inward solidification times calculated by the model are compared with those obtained from references. The results are in good agreement. The great advantage of the proposed model is its simplicity and is sufficiently accurate for most practical

关键词： analytical planar cylindrical spherical solidification theory constant heat flux ratio.

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Key Techniques in Real Time Digital Simulation for Closed-loop Testing of HVDC Systems

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CSEE Journal of Power and Energy Systems 2017年第2期3卷 125-130页

作者： Yi Zhang Hui Ding Rick Kuffel RTDS Technologies inc. WinnipegManitobaCanada

This paper introduces several key techniques in realtime digital simulation for closed-loop testing of high voltage direct current(HVDC)systems,inc.uding line commutated converter(LCC)HVDC valve group models,modular multilevel converter(MMC)HVDC models,phase domain frequency dependent transmission line models,and switchable filter *** issues such as background,algorithms,implementations,applications,and validation of these models are *** techniques represent the most advanced technology in modelling HVDC systems on a real time *** models have been implemented on the RTDS Simulator,a comprehensive real time power system digital simulation tool.

关键词： HVDC real time simulation

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A New Method to Calculate Water Film Stiffness and Damping for Water Lubricated Bearing with Multiple Axial Grooves

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Chinese Journal of Mechanical Engineering 2020年第5期33卷 167-184页

作者： Guojun Ren Thordon Bearings inc. 3225BurlingtonON L7M 1A6Canada

Water lubricated guide bearings for hydro turbines and pumps are conventionally designed with multiple axial grooves to provide effectively cooling and flushing away *** to the variety of groove configuration in terms of number and size,a predication of their performance is *** paper deals with an analytical procedure to investigate groove effect on load capacity,stiffness and damping for this type of bearing where it is considered as an assembly of many inc.ined slide *** result can be applied to bearings made of hard materials combined with low bearing pressure.

关键词： Water lubricated bearing Groove effect Stiffness and damping inc.ined slide bearing

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A reinforcement learning approach for thermostat setpoint preference learning

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Building Simulation 2024年第1期17卷 131-146页

作者： Hussein Elehwany Mohamed Ouf Burak Gunay Nunzio Cotrufo Jean-Simon Venne Department of Environmental Engineering Carleton UniversityOttawaCanada Departmentof Building Civiland Environmental EngineeringConcordia UniversityMontrealCanada BrainBox Al inc. MontrealCanada

Occupant-centric controls(OcC)is an indoor climate control approach whereby occupant feedback is used in the sequence of operation of building energy *** OcC has been used in a wide range of building applications,an OcC category that has received considerable research interest is learning occupants'thermal preferences through their thermostat interactions and adapting temperature setpoints *** recent studies used reinforcement learning(RL)as an agent for OcC to optimize energy use and occupant *** studies depended on predicted mean vote(PMV)models or constant comfort ranges to represent comfort,while only few of them used thermostat *** paper addresses this gap by introducing a new off-policy reinforcement learning(RL)algorithm that imitates the occupant behaviour by utilizing unsolicited occupant thermostat *** algorithm is tested with a number of synthetically generated occupant behaviour models implemented via the Python APl of *** simulation results indicate that the RL algorithm could rapidly learn preferences for all tested occupant behaviour scenarios with minimal exploration *** substantial energy savings were observed with most occupant scenarios,the impact on the energy savings varied depending on occupants'preferences and thermostat use behaviour stochasticity.

关键词： reinforcement learning preference learning occupant-centric controls smart thermostats off-policy learning

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Solvent Extraction in Hydrometallurgy: Present and Future

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Tsinghua Science and Technology 2006年第2期11卷 137-152页

作者： Gordon M. Ritcey G. M. Ritcey and Associates inc. Ottawa Canada

During the past 10 years, there have been inc.emental advances in the application of solvent extraction to process hydrometallurgy. The most cited areas in the literature inc.ude chemistry, chemical engineering, pilot plants, and plant operation. Within these areas, there were considerable interest in synergism, diluents, degradation, contactors, surfactants, hydrometallurgical applications, environmental and secondary applications, and health and safety. The summary to the present is followed by a prediction for the future in the above areas of interest. These inc.ude the use of speciation; improved understanding of the role of surfactants on the system; optimization through modelling, pilot plants, and contactor selection; improvements in plant operation; further new applications; and plant safety. The review has indicated that considerable knowledge is now available to optimize and improve on process design and plant applications.

关键词： chemical engineering coalescence degradation diluents dispersion droplet size electrostaticpseudoliquid membrane environmental and secondary recovery hydrometallurgical applications

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Modeling displacement flow inside a full-length casing string for well cementing

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Petroleum Research 2024年第1期9卷 1-16页

作者： Hu Dai Ali Eslami Jason Schneider Gefei Liu Fred Schwering Pegasus Vertex Inc.USA Laval University Canada Sanjel Energy Services Canada Athabasca Oil Corporation Canada

While computer modeling of annular displacement efficiency is widely applied in cementing engineering,modeling the displacement flow inside a casing or drill string for cementing operations has received less *** predicting displacement efficiency inside a full-length pipe is desired by cementing engineers,the attempt of developing a model with both efficiency and accuracy faces *** to computer simulators for this purpose is *** with annular flow,the displacement flow inside pipe,although within a simpler geometry and without eccentricity effect,is not simpler in physics,modelling strategy and predictability,because a variety of flow patterns and flow instabilities can develop to create complicated fluid *** this paper,we present an integrated numerical model developed to simulate displacement flows inside a full-length pipe,which connects an existing annulus model to enable complete displacement simulations of cementing *** model uses three-dimensional grid to solve fluid concentrations with degrees of mixing,and inc.rporates flow instability detection and flow regime *** in cementing,the model accounts for effects of pumping rate,well inc.ination,pipe rotation,fluid densities,rheological parameters and *** computationally efficient model does not rely on high-resolution mesh as often required by conventional Computational Fluid Dynamics models,thus it is suitable to be implemented in a cementing software for daily use by well cementing *** methodology of the model is discussed in detail in this *** validate the model,we examine simulation results against experimental results obtained in our laboratory tests and CFD simulations;acceptable agreement is found under different testing *** also presented two case studies of real cementing jobs with cement evaluation logs compared to simulation results,showing that the model can predict consistent displacement efficie

关键词： Inside pipe displacement Displacement efficiency Numerical model Primary cementing Displacement flow

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The use of mathematics in software quality assurance

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Frontiers of Computer Science 2012年第1期6卷 3-16页

作者： David Lorge PARNAS Middle Road Software Inc. Ottawa K1V 1V5 Canada

The use of mathematics for documenting, in- specting, and testing software is explained and illus- trated. Three measures of software quality are described and discussed. Then three distinc. complementary approaches to software quality assurance are presented. A case study, the testing and inspection of a safety-critical system, is discussed in detail.

关键词： software quality assurance documentationbased inspection documentation based testing

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