scholarly journals Seismic Hybrid Simulation of Stiff Structures: Overview and Current Advances

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Stathis N. Bousias
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Testing ◽  
Hybrid Simulation ◽  
Structural Testing ◽  
Structural Elements ◽  
Actuator Control ◽  
Pseudodynamic Testing ◽  
Test Process ◽  
Control Accuracy

Advances in the area of structural testing have in recent years led to hybrid simulation, that is, the advanced structural experimental method that encompasses the traditional pseudodynamic testing method and relies on substructuring to offer the advantage of combining the actual experimental testing of selected parts of the structure to the numerical treatment of the rest. The experimental part usually involves simplified test setups and structural elements with few degrees of freedom. Thus, issues of cross-coupling present in testing MDOF structures have not been treated adequately so far. In addition, it has been realized that when it comes to testing very stiff structures, in which the above phenomena are accentuated, further problems arise in relation to the quality of actuator control (accuracy of imposed displacements and stability of the test process). Few studies have focused on these issues, thus necessitating more work in the future. The present study provides an overview of the approaches that have been adopted so far, reports on recent advancements, and raises the points in which more research is needed.

Driving Torsion Scans with Wavefront Propagation

2020 ◽  
Author(s):  
Yudong Qiu ◽  
Daniel Smith ◽  
Chaya Stern ◽  
mudong feng ◽  
Lee-Ping Wang
Keyword(s):  
Potential Energy ◽  
Force Field ◽  
Degrees Of Freedom ◽  
Computational Cost ◽  
Initial Guess ◽  
Field Development ◽  
Force Field Development ◽  
Wavefront Propagation ◽  
Open Source Software Package

<div>The parameterization of torsional / dihedral angle potential energy terms is a crucial part of developing molecular mechanics force fields.</div><div>Quantum mechanical (QM) methods are often used to provide samples of the potential energy surface (PES) for fitting the empirical parameters in these force field terms.</div><div>To ensure that the sampled molecular configurations are thermodynamically feasible, constrained QM geometry optimizations are typically carried out, which relax the orthogonal degrees of freedom while fixing the target torsion angle(s) on a grid of values.</div><div>However, the quality of results and computational cost are affected by various factors on a non-trivial PES, such as dependence on the chosen scan direction and the lack of efficient approaches to integrate results started from multiple initial guesses.</div><div>In this paper we propose a systematic and versatile workflow called \textit{TorsionDrive} to generate energy-minimized structures on a grid of torsion constraints by means of a recursive wavefront propagation algorithm, which resolves the deficiencies of conventional scanning approaches and generates higher quality QM data for force field development.</div><div>The capabilities of our method are presented for multi-dimensional scans and multiple initial guess structures, and an integration with the MolSSI QCArchive distributed computing ecosystem is described.</div><div>The method is implemented in an open-source software package that is compatible with many QM software packages and energy minimization codes.</div>

The Development of a Myoelectric Training Tool for Above-Elbow Amputees

2012 ◽  
Vol 6 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Michael R Dawson ◽  
Farbod Fahimi ◽  
Jason P Carey
Keyword(s):  
Degrees Of Freedom ◽  
Learning Task ◽  
Robotic Arm ◽  
Signal Acquisition ◽  
Myoelectric Prosthesis ◽  
Training Tool ◽  
Myoelectric Prostheses ◽  
Training Systems ◽  
Targeted Muscle Reinnervation

The objective of above-elbow myoelectric prostheses is to reestablish the functionality of missing limbs and increase the quality of life of amputees. By using electromyography (EMG) electrodes attached to the surface of the skin, amputees are able to control motors in myoelectric prostheses by voluntarily contracting the muscles of their residual limb. This work describes the development of an inexpensive myoelectric training tool (MTT) designed to help upper limb amputees learn how to use myoelectric technology in advance of receiving their actual myoelectric prosthesis. The training tool consists of a physical and simulated robotic arm, signal acquisition hardware, controller software, and a graphical user interface. The MTT improves over earlier training systems by allowing a targeted muscle reinnervation (TMR) patient to control up to two degrees of freedom simultaneously. The training tool has also been designed to function as a research prototype for novel myoelectric controllers. A preliminary experiment was performed in order to evaluate the effectiveness of the MTT as a learning tool and to identify any issues with the system. Five able-bodied participants performed a motor-learning task using the EMG controlled robotic arm with the goal of moving five balls from one box to another as quickly as possible. The results indicate that the subjects improved their skill in myoelectric control over the course of the trials. A usability survey was administered to the subjects after their trials. Results from the survey showed that the shoulder degree of freedom was the most difficult to control.

scholarly journals Development and assessment of a telesonography system for musculoskeletal imaging

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Mohammed Obaid ◽  
Qianwei Zhang ◽  
Scott J. Adams ◽  
Reza Fotouhi ◽  
Haron Obaid
Keyword(s):  
Degrees Of Freedom ◽  
Ultrasound Images ◽  
Ultrasound Probe ◽  
Rural And Remote ◽  
Significant Delay ◽  
Remote Communities ◽  
Internet Connection ◽  
Good For ◽  
4 Degrees Of Freedom

Abstract Background Telesonography systems have been developed to overcome barriers to accessing diagnostic ultrasound for patients in rural and remote communities. However, most previous telesonography systems have been designed for performing only abdominal and obstetrical exams. In this paper, we describe the development and assessment of a musculoskeletal (MSK) telesonography system. Methods We developed a 4-degrees-of-freedom (DOF) robot to manipulate an ultrasound probe. The robot was remotely controlled by a radiologist operating a joystick at the master site. The telesonography system was used to scan participants’ forearms, and all participants were conventionally scanned for comparison. Participants and radiologists were surveyed regarding their experience. Images from both scanning methods were independently assessed by an MSK radiologist. Results All ten ultrasound exams were successfully performed using our developed MSK telesonography system, with no significant delay in movement. The duration (mean ± standard deviation) of telerobotic and conventional exams was 4.6 ± 0.9 and 1.4 ± 0.5 min, respectively (p = 0.039). An MSK radiologist rated quality of real-time ultrasound images transmitted over an internet connection as “very good” for all telesonography exams, and participants rated communication with the radiologist as “very good” or “good” for all exams. Visualisation of anatomic structures was similar between telerobotic and conventional methods, with no statistically significant differences. Conclusions The MSK telesonography system developed in this study is feasible for performing soft tissue ultrasound exams. The advancement of this system may allow MSK ultrasound exams to be performed over long distances, increasing access to ultrasound for patients in rural and remote communities.

Optimal Parameter Design of Solder Residue in Flip Chip Process by Using Taguchi Method

2010 ◽  
Vol 443 ◽  
pp. 543-548
Author(s):  
Jian Long Kuo ◽  
Kai Lun Chao ◽  
Chun Cheng Kuo
Keyword(s):  
Taguchi Method ◽  
Product Quality ◽  
Manufacturing Process ◽  
Flip Chip ◽  
Optimal Parameter ◽  
Experimental Testing ◽  
Signal To Noise Ratio ◽  
Optimal Solution ◽  
Passive Component

Because the solder residue was found in the manufacturing process which greatly affected the product quality, the purpose of this paper was to make the product quality improved and to find an optimal solution for process parameters in the flip chip process. The experimental testing was based on SMT manufacturing process. The amount and size of solder left on passive component in the process of manufacturing were considered as the quality traits. Since too many solders left on the passive component side during flux cleaning process, it was possible that the balling would be flowed into the chip, which caused the bump short in the chip and affected the quality of the product. In this paper, orthogonal array by using Taguchi method is adopted as the effective experimental method with the least experimental runs. Also, based on the quality evaluation of signal-to-noise ratio, the ANOVA is used to evaluate the effects of quality target according to the experimental results. The results reveal that the optimization in the process is confirmed. Therefore, this study can effectively improve the solder residue in semiconductor manufacturing process.

Development of a Hybrid Simulation Computational Model for Steel Braced Frames

2018 ◽  
Vol 763 ◽  
pp. 609-618
Author(s):  
Ali Imanpour ◽  
Robert Tremblay ◽  
Martin Leclerc ◽  
Romain Siguier
Keyword(s):  
Computational Model ◽  
Hybrid Simulation ◽  
Structural Testing ◽  
Frame Structure ◽  
Axial Stiffness ◽  
Braced Frames ◽  
Element Analysis ◽  
Braced Frame ◽  
Concentrically Braced Frame ◽  
Dynamic Hybrid

Hybrid simulation is an economical structural testing technique in which the critical part of the structure expected to respond in the inelastic range is tested physically whereas the rest of the structure is modelled numerically using a finite element analysis program. The article describes the development of a computational model for the hybrid simulation of the seismic collapse of a steel two-tiered braced frame structure due to column buckling. The column stability response in multi-tiered braced frames is first presented using a pure numerical model of the braced frame studied. The development of the hybrid simulation computational model is then discussed. Effects of initial out-of-straightness imperfections and axial stiffness, P-Delta analysis approach, and gravity analysis technique on the hybrid simulation results are evaluated using a numerical hybrid simulation model. Finally, the results of a continuous pseudo-dynamic hybrid simulation of the seismic response of the steel multi-tiered concentrically braced frame are presented. The test showed that failure of columns by instability is a possibility and can lead to collapse of multi-tiered braced frames, as was predicted by numerical analysis. Furthermore, suitable modeling methods are proposed for hybrid simulation of steel braced frame structures.

About quality of dissertations, or this strange GOST

2021 ◽  
pp. 65-75
Author(s):  
Yu.V. Kazakov ◽  
Keyword(s):  
Graduate Students ◽  
System Approach ◽  
Scientific Methodology ◽  
Structural Elements ◽  
Academic Degree ◽  
Practical Guide ◽  
Classical Methodology ◽  
And Performance

Examined is relevance of a subject of work is caused by the continuing deterioration of dissertation works. Therefore, article purpose is to define the system reason of deterioration of training of the top skills by the analysis of contents and structure of theses. The main shortcomings of dissertations, and understanding of their structural elements by applicants of an academic degree by communication with them in the course of preparation and carrying out preliminary protection of these were analyzed. Results of the analysis were compared to requirements of classical methodology and to interpretation of these requirements in the methodical managements and in publications. The essential system reason of decline in quality of dissertation works is in their traditional unsystematic structure, whith investigation withdrawal from scientific methodology and particular leveling of motivation to the analysis of a condition of a question and the received results of researches and also to system approach to the thesis, need of strengthening of methodological training of graduate students according to the uniform nation-wide program providing system approach to the organization of researches for all scientific specialties, and processing’s of the “Thesis and Abstract of the Thesis” standard according to classical requirements of scientific methodology and the system approach to dissertation work Is shown. The system scheme of the thesis, which can make a manual basis is the practical guide to organization and performance of dissertation work for training of graduate students and applicants is offered.

scholarly journals Experimental Issues in Testing a Semiactive Technique to Control Earthquake Induced Vibration

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Nicola Caterino ◽  
Mariacristina Spizzuoco ◽  
Julian M. Londoño ◽  
Antonio Occhiuzzi
Keyword(s):  
Large Scale ◽  
Experimental Testing ◽  
Practical Experience ◽  
Structural Testing ◽  
Frame Structure ◽  
Semiactive Control ◽  
Electrical Currents ◽  
Wide Range ◽  
And Control ◽  
Steel Frame Structure

This work focuses on the issues to deal with when approaching experimental testing of structures equipped with semiactive control (SA) systems. It starts from practical experience authors gained in a recent wide campaign on a large scale steel frame structure provided with a control system based on magnetorheological dampers. The latter are special devices able to achieve a wide range of physical behaviours using low-power electrical currents. Experimental activities involving the use of controllable devices require special attention in solving specific aspects that characterize each of the three phases of the SA control loop: acquisition, processing, and command. Most of them are uncommon to any other type of structural testing. This paper emphasizes the importance of the experimental assessment of SA systems and shows how many problematic issues likely to happen in real applications are also present when testing these systems experimentally. This paper highlights several problematic aspects and illustrates how they can be addressed in order to achieve a more realistic evaluation of the effectiveness of SA control solutions. Undesired and unavoidable effects like delays and control malfunction are also remarked. A discussion on the way to reduce their incidence is also offered.

scholarly journals SWOT-F-ANALYSIS OF RESTAURANT BUSINESS IN KHARKIV

2020 ◽  
pp. 192-200
Author(s):  
Viktor Seliutin ◽  
Leonid Yatsun ◽  
Oleksandr Olshanskiy
Keyword(s):  
Swot Analysis ◽  
Fractal Theory ◽  
Restaurant Industry ◽  
Strategic Analysis ◽  
Economic Systems ◽  
Structural Elements ◽  
Fractal Structures ◽  
Development Scenarios ◽  
Fractal System

Introduction. The article deals with the evaluation of the Kharkiv restaurant industry as a fractal system by means of SWOT-f analysis. Modern ideas about socio-economic systems are based on a synergistic concept that is organically linked to fractal theory. By fractal structure, the restaurant industry is a seven-tier holarchical system that contains such determinants as the assortment and quality of the restaurant service, technology, management, marketing, changes, forms of clustering and competitiveness. The systematic nature of the restaurant industry implies a similar structure of external factors. One of the common methods of strategic evaluation is SWOT analysis. The proposed method of SWOT-f analysis is a modified tool for strategic analysis of sectoral and regional-sectoral systems, which are considered as fractal structures, which ensures the adequacy of their perception and accuracy of forecasting. Purpose of the article is to identify the main parameters of the modified SWOT-f-analysis as a strategic tool for evaluating the restaurant industry, assessing the strengths and weaknesses, as well as threats and opportunities for the development of the restaurant industry in Kharkiv as a fractal system in three scenarios: pessimistic, realistic and optimistic. Method. A modified SWOT-f analysis was used to evaluate the restaurant industry, which consists in structuring the factors of influence on the activity of the enterprise on fractal principles, and also assumes the application of three development scenarios: pessimistic, realistic and optimistic. Result. It is determined that SWOT-f-analysis is a more expedient tool of strategic analysis, since it contains all elements of classical SWOT-analysis; structured as a holarchical system, which gives it greater logic; built on evolutionary principles; has a more reasonable connection between internal structural elements and environmental factors; and also allows to define the limits of setting the goals of the enterprise development in pessimistic, realistic and optimistic scenarios. The assessment of the strengths and weaknesses, as well as the threats and opportunities for the development of the restaurant industry allowed to identify a more logical and structured profile for each scenario.

scholarly journals Design of Novel BELBIC Controlled Semi-Active Suspension and Comparative Analysis with Passive and PID Controlled Suspension

2021 ◽  
Vol 18 (5) ◽  
Author(s):  
Pankaj SHARMA ◽  
Vinod KUMAR
Keyword(s):  
Human Body ◽  
Degrees Of Freedom ◽  
Active Suspension ◽  
Driver Model ◽  
Ride Quality ◽  
Body Parts ◽  
Hybrid Techniques ◽  
Design Engineers ◽  
Mass Displacement

Passenger comfort, quality of ride, and handling have broughta lot of attention and concern toautomotive design engineers. These 2 parameters must have optimum balance as they have an inverse effect on each other. Researchers have proposed several approaches and techniques like PID control, fuzzy approach, GA, techniques with inspiration from nature and hybrid techniques to attain the same. A new controller based on the learning behavior of the human brain has been used for the control of semi-active suspension in this study. The controller is known as the Brain Emotional Learning-Based Intelligent Controller (BELBIC). A one-fourth model of car along with the driver model having 6 degrees of freedom (DOF) wasmodeled and simulated. The objective of the studywasto analyze the performance of the proposed controller for improving the dynamic response of the vehicle model coupled with complex biodynamic models of the human body as a passenger, making the whole dynamic system very complex to control. The performance wasanalyzed based on percentage reduction in the overshoot of the vehicle’s sprung mass as well as different human body parts when subjected to road disturbances. The proposed controller performance wascompared with the PID controller, widely used in semi-active suspension. The simulation results obtained for BELBIC controlled system for circular road bump showed that the overshoot of passenger head and body wasreduced by 18.84 and 18.82 %, respectively and reduction for buttock and leg displacement was18.87 %. The vehicle’s seat and sprung mass displacement displayedan improvement of 18.90 and 18.51 %. The overshoot of passenger's head and body displacement wasimproved by 19.79and 19.62 %,respectively, whereas improvement for buttock & leg, vehicle’s seat, and sprung mass displacement were19.81, 20.00, and 20.49 % against trapezoidal speed bump. The PID controlled suspension disclosed an improvement of 8.74, 8.53, 8.75, 11.11, 14.75 % against circular bump and 10.72, 10.33, 10.73, 11.11 and 11.75 % against trapezoidal bump for overshoot reduction of passenger head, body, buttock & leg, vehicle’s seat and sprung mass displacement, respectively. The proposed BELBIC controlled semi-active suspension outperformed the widely used PID controlled semi-active suspension and indicated asignificant improvement in the ride quality of the vehicle.

scholarly journals A Concept Design of an Adaptive Tendon Driven Mechanism for Active Soft Hand Orthosis

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 21
Author(s):  
Bruno Lourenço ◽  
Vitorino Neto ◽  
Rafhael de Andrade
Keyword(s):  
Degrees Of Freedom ◽  
Low Cost ◽  
Vital Role ◽  
Dorsal Side ◽  
Concept Design ◽  
Cord Injury ◽  
3D Printed ◽  
Biomechanical Constraints ◽  
Active Orthosis

The Hands exert a vital role in the simplest to most complex daily tasks. Losing the ability to make hand movements, which is usually caused by spinal cord injury or stroke, dramatically impacts the quality of life. In order to counteract this problem, several assisting devices have been proposed, but they still present several usage limitations. The marketable orthoses are generally either the static type or over-expensive active orthosis that cannot perform the same degrees of freedom (DoF) that a hand can do. This paper presents a conceptual design of a tendon-driven mechanism for hand’s active orthosis. This study is a part of an effort to develop an effective and low-cost hand’s orthosis for people with hand paralysis. The tendon design proposed was thought to comply with some requisitions such as lightness and low volume, as well as fit with the biomechanical constraints of the hand joints to enable a comfortable use. The mechanism employs small cursors on the phalanges to allow the tendons to run on the dorsal side and by both sides of the fingers, allowing 2 DoF for each finger, and one extra tendon enlarges the hands’ adduction nuances. With this configuration, it is simple enough to execute the flexion and extension movements, which are the most used movements in daily actives, using one single DC actuator for one DoF to reduce manufacturing costs, or with more DC actuators to enable more natural hand coordination. This system of actuation is suitable to create soft exoskeletons for hands easily embedded into 3D printed parts, which could be merged over statics thermoplastic orthosis. The final orthosis design allows dexterous finger movements and force to grasp objects and perform tasks comfortably.

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