Analytical and experimental studies on midstory isolated buildings with modal coupling effect

2012 ◽  
Vol 42 (2) ◽  
pp. 201-219 ◽  
Author(s):  
Shiang-Jung Wang ◽  
Jenn-Shin Hwang ◽  
Kuo-Chun Chang ◽  
Meng-Hui Lin ◽  
Bo-Han Lee
Keyword(s):  
Coupling Effect ◽  
Experimental Studies ◽  
Modal Coupling

scholarly journals Numerical and experimental studies on a novel magneto-rheological fluid brake based on fluid–solid coupling

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987900 ◽  
Author(s):  
Shujun Li ◽  
Wenjun Meng ◽  
Yao Wang
Keyword(s):  
Heat Dissipation ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Test System ◽  
Structure Design ◽  
Brake Disc ◽  
Braking Torque ◽  
Braking Process ◽  
Magneto Rheological ◽  
The Impact

The previous work of the authors indicated that the fluid–solid coupling effect of the magneto-rheological fluid and the brake disc is a necessary focus during braking process. In this study, a novel design of magneto-rheological fluid brake was proposed and studied theoretically and numerically, aiming to solve the prominent problem of heat dissipation, especially in the case of single emergency braking. First, based on the modified Bingham model, a parameter defined as the apparent equivalent viscosity was utilized to represent the relationship of magnetic field, flow field, and temperature field. The braking torque and the formula for calculating the impact factor of fluid–solid coupling employed for characterizing the associations among the thermal field and the stress field were established based on fluid–solid coupling. With a detailed explanation of simulation method, the distribution disciplinarian’s numerical simulation of each field was analyzed using COMSOL software. To validate the accuracy of the established model on the designed magneto-rheological fluid brake, the prototype was also manufactured, and results achieved experimentally which were measured on inertia test system of brake, for braking torque, motion parameters, and surface temperature in braking process, were compared with simulations. Simulation results manifested that the designed magneto-rheological fluid brake’s magnetic circuit structure is feasible based on magnetic induction intensity distribution. Finally, it has been shown that the simulations appear to be basically consistent with the experimental results, and the heat dissipation of the designed magneto-rheological fluid brake is partially improved. These results might contribute to the structure design, optimization, and improvement of magneto-rheological fluid products, extending the previous work on fluid–solid coupling analyses.

AN APPROXIMATION METHOD FOR COMPUTING THE DYNAMIC RESPONSES AND EQUIVALENT STATIC WIND LOADS OF LARGE-SPAN ROOF STRUCTURES

2010 ◽  
Vol 10 (05) ◽  
pp. 1141-1165 ◽  
Author(s):  
XUANYI ZHOU ◽  
MING GU
Keyword(s):  
Coupling Effect ◽  
Coupling Factor ◽  
Dynamic Responses ◽  
Wind Loads ◽  
Inertia Force ◽  
Large Span ◽  
Load Distributions ◽  
Modal Coupling ◽  
Vibration Responses ◽  
Equivalent Static Wind Loads

Due to their sensitivity to wind, the design of large-span roofs is generally governed by wind loads. For some flexible large-span roofs with low damping and concentrated modes, the effect of multi-mode coupling should be taken into account in computing the resonant buffeting response and equivalent static wind loads. Such an effect is considered by the modified SRSS method in this paper via the modal coupling factor. Based on the same SRSS method, the equivalent static wind loads combining the mean, background, and resonant components, are computed. Particularly, the background and resonant components are computed by the LRC method and the equivalent inertia force method considering the modal coupling effects by the modified SRSS method, respectively. The method is then applied to the computation of wind-induced vibration responses and equivalent static wind load distributions of a real large-span roof. The results show that the modal coupling effect on the resonant component can be identified by the present method with high accuracy.

Theoretical and Experimental Studies of Chatter in Turning for Uniform and Stepped Workpieces

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
S. D. Yu ◽  
V. Shah
Keyword(s):  
Coupling Effect ◽  
Equations Of Motion ◽  
Experimental Studies ◽  
Beam Theory ◽  
Summation Method ◽  
Cutting Process ◽  
Mode Shapes ◽  
Coupled Equations ◽  
Modal Summation ◽  
System Equations

This paper presents a method for predicting regenerative chatter onset conditions for uniform and stepped workpieces. The lateral deflections of flexible workpieces are modeled using the Timoshenko beam theory and three-node beam finite elements. The modal summation method is employed in conjunction with an adaptive remeshing scheme to determine the varying natural frequencies and varying mode shapes of workpieces during a cutting process, and to reduce the system equations of motion in terms of nodal variables to coupled equations of motion in terms of the modal coordinates. Various simulations were conducted and presented in this paper for understanding the gyroscopic and cross-coupling effect, and effects of other system and cutting process parameters on chatter onset conditions. Six experiments were carried out on an engine lathe for three uniform and three stepped workpieces to verify the theoretical chatter onset conditions. Good agreement in chatter onset conditions was observed between the simulations and the experiments.

scholarly journals Monte Carlo and Experimental Magnetic Studies of Molecular Spintronics Devices

NANO ◽  
2015 ◽  
Vol 10 (04) ◽  
pp. 1550056 ◽  
Author(s):  
Pawan Tyagi ◽  
Christopher D'Angelo ◽  
Collin Baker
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Magnetic Tunnel Junction ◽  
Magnetic Interactions ◽  
Magnetic Studies ◽  
Magnetic Molecules ◽  
Wide Range ◽  
Different Temperatures

Molecule-based spintronics devices (MSDs) are highly promising candidates for discovering advanced logic and memory computer units. An advanced MSD will require the placement of paramagnetic molecules between the two ferromagnetic (FM) electrodes. Due to extreme fabrication challenges, only a couple of experimental studies could be performed to understand the effect of magnetic molecules on the overall magnetic and transport properties of MSDs. To date, theoretical studies mainly focused on charge and spin transport aspects of MSDs; there is a dearth of knowledge about the effect of magnetic molecules on the magnetic properties of MSDs. This paper investigates the effect of magnetic molecules, with a net spin, on the magnetic properties of 2D MSDs via Monte Carlo (MC) simulations. Our MC simulations encompass a wide range of MSDs that can be realized by establishing different kinds of magnetic interactions between molecules and FM electrodes at different temperatures. The MC simulations show that ambient thermal energy strongly influenced the molecular coupling effect on the MSD. We studied the nature and strength of molecule couplings (FM and antiferromagnetic) with the two electrodes on the magnetization, specific heat and magnetic susceptibility of MSDs. For the case when the nature of molecule interaction was FM with one electrode and antiferromagnetic with another electrode the overall magnetization shifted toward zero. In this case, the effect of molecules was also a strong function of the nature and strength of direct coupling between FM electrodes. In the case when molecules make opposite magnetic couplings with the two FM electrodes, the MSD model used for MC studies resembled with the magnetic tunnel junction based MSD. The experimental magnetic studies on these devices are in agreement with our theoretical MC simulations results. Our MC simulations will enable the fundamental understanding and designing of a wide range of novel spintronics devices utilizing a variety of molecules, nanoclusters and quantum dots as the device elements.

scholarly journals A Robust Region Control Approach for Simultaneous Trajectory Tracking and Physical Human-Robot Interaction

2021 ◽  
Author(s):  
Xiangyun Li ◽  
QI LU ◽  
Jiali Chen ◽  
Kang Li
Keyword(s):  
Trajectory Tracking ◽  
Human Subject ◽  
Robot Manipulator ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Human Robot Interaction ◽  
Robot Interaction ◽  
Target Region ◽  
Control Approach ◽  
Region Tracking

In this work, the uncertainty and disturbance estimator (UDE)-based robust region tracking controller for a robot manipulator is developed to achieve the moving target region trajectory tracking and the compliant human-robot interaction simultaneously. Utilizing the back-stepping control approach, the UDE is seamlessly fused into the region tracking control framework to estimate and compensate the model uncertainty and external disturbance, such as unknown payload, unmodeled joint coupling effect and friction. The regional feedback error is derived from the potential function to drive the robot manipulator end-effector converging into the target region, where the robot manipulator can be passively manipulated based on the needs of human to achieve the compliant physical human-robot interaction. Extensive experimental studies are carried out with a universal robots 10 manipulator to validate the effectiveness of the proposed method for moving region trajectory tracking, handling unknown payload and compliant physical human-robot interaction. The superior robustness of the proposed approach is demonstrated by comparison with the existing controller under the adverse effect of unknown payload. The humanrobot interaction is achieved in a shared autonomy manner with the cooperation of the manipulator and the human subject to accomplish the temperature measurement task, where the variation in human-subject height and the complexity of aiming the thermometer are successfully accommodated.

The Combined Effects of Hydrostatic Pressure and Strain-Rate on the Compressive Properties of a Laminated, Multi-Directional, Graphite/Epoxy Thick-Composite

1998 ◽  
Vol 32 (1) ◽  
pp. 49-67 ◽  
Author(s):  
K. D. Pae ◽  
K. S. Carlson
Keyword(s):  
Hydrostatic Pressure ◽  
Strain Rate ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Strain Rates ◽  
Combined Effects ◽  
Compressive Properties ◽  
Stress Strain ◽  
Simultaneous Application ◽  
Low Strain Rate

Experimental studies of the combined effects of hydrostatic pressure and strain-rate on the compressive properties of a laminated, multi-directional graphite fiber/epoxy matrix thick-composite have been made. It has been determined that the compressive stress-strain behavior of the thick-composite is dependent significantly on hydrostatic pressure and strain-rate. The hydrostatic pressure ( P) applied was 1 bar, 1 kbar, 2 kbar, and 3 kbar and the average strain-rates (ε) used for the studies were 6.51 x 10−2%/s (quasi-static or low strain-rate) and 1.27%/s (high strain-rate). The compressive properties—namely the Young's modulus ( E), the yield strength (σγ) when one occurred, the ultimate strength (σ U) or the fracture strength (σ f), and the fracture strain (ε f)—were determined as a function of P and ε. The E increased bilinearly with P at the low and the high is with the discontinuity point located at ~2 kbar. It is particularly important to note that there was a coupling effect of P and ε on E of the thick-composite. The coupling effect was that the value of E under simultaneous application of P and the high ε was greater than the sum of the values of E under separate application of P and the high ε. The multi-directional thick-composite behaved like a brittle material, exhibiting only linear elastic stress-strain curves, under 1 bar and the low strain-rate. It, however, underwent 2% off-set yielding when P ≥ 2 kbar under the low and the high ε S. The σ F remained virtually unchanged at each pressure level, regardless of strain rates used but the σ F decreased with ε.

A Monte Carlo Study of Molecular Spintronics Devices

2013 ◽  
Author(s):  
Pawan Tyagi ◽  
Christopher D’Angelo
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Exchange Coupling ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Magnetic Molecules ◽  
Molecular Spintronics ◽  
Ferromagnetic Electrodes ◽  
Wide Range ◽  
And Control

Molecular spintronics devices (MSDs) are capable of harnessing the controllable transport and magnetic properties of molecular device elements and are highly promising candidates for revolutionizing computer logic and memory. These advanced MSD can enable the next generation of instrumentation and control devices for the wide range of mechanical engineering systems. A MSD is typically produced by placing magnetic molecule(s) between the two ferromagnetic electrodes. Recent experimental studies show that some magnetic molecules produced unprecedented strong exchange couplings between the two ferromagnetic electrodes, leading to intriguing magnetic and transport properties in a MSD. Future development of MSDs will critically depend on obtaining an in-depth understanding of the molecule induced exchange coupling, and its impact on MSD’s switchability, functional temperature range, stability etc. However, the large size of MSD systems and unsuitable device designs are the two biggest hurdles in theoretical and experimental studies of magnetic attributes produced by molecules in a MSD. This research theoretically studies the MSD by performing Monte Carlo simulations (MCS). The effect of magnetic molecule induced exchange coupling was studied at different temperature and for different device sizes — represented by a 2D Ising model. Our MCS shows that thermal energy of the MSD strongly influenced the molecular coupling effect. We studied the effect of a wide range of molecule-metal electrode couplings on the fundamental properties of MSDs. If molecules induced exchange coupling increased beyond a threshold limit a MSD acquired dramatically new attributes. Our MCS exhibited that the transition points in MSD’s magnetic properties was the interplay of temperature and molecular coupling strength. These simulations will allow the understanding of fundamental device mechanisms behind the functioning of novel MSDs. Our MSD model represents a myriad of magnetic molecules and ferromagnets combinations promising for realizing experimental MSDs. These MCS will also assist in designing new class of MSDs with desired attributes for advanced computers and control systems.

scholarly journals Research Progress on Curved Plates in China: Applications in Architecture

2022 ◽  
Vol 12 (2) ◽  
pp. 550
Author(s):  
Yiheng Song ◽  
Ziying Wang ◽  
Jie Chen ◽  
Jinxiang Chen
Keyword(s):  
Optical Properties ◽  
Numerical Calculation ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Curved Surface ◽  
Research Progress ◽  
Curved Surfaces ◽  
Future Directions ◽  
Acoustic Characteristics ◽  
Development Direction

Curved surfaces can give plates a unique aesthetic effect and physical advantages in acoustics and optics. Assembling such curved plates can greatly improve the image of buildings and enrich their functions. It is thus not surprising to notice that their wide applications in designed or completed buildings in China have become a trend. Thus, this study offers a comprehensive summary of the application progress of curved plates in the architectural field from three aspects: image expression, acoustic characteristics, and optical characteristics. On this basis, future directions are proposed. The main findings or suggestions are as follows: (1) climate harshness has increased recently, and the safety of structures and materials and the coupling effect of the two must be fully considered when designing the shapes of curved surface buildings; (2) research on the mechanism and numerical calculation of curved diffuser systems with different sizes and curvatures needs to be further developed; and (3) experimental studies of various and complex curved plates and different conditions to explore their optimal reflectivity, transmittance, absorptivity, and other optical properties will be an important development direction.

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