scholarly journals Dynamic analysis of strength and human-comfort level of the football stadium structures at coordinated movements of audience

2018 ◽  
Vol 196 ◽  
pp. 02032
Author(s):  
Sergey Bulushev ◽  
Artem Bunov
Keyword(s):  
Dynamic Performance ◽  
Comfort Level ◽  
Dynamic Loads ◽  
National Standard ◽  
Human Comfort ◽  
Limit Values ◽  
Technical Documents ◽  
The Time Domain ◽  
Certified Software ◽  
Design Construction

In the design of stadiums and other sports facilities it is necessary to take into account the dynamic performance caused by coordinated movement of groups of people. National standard technical documents do not contain guidance on the setting of dynamic loads caused by people, as well as admissible dynamic parameters of grandstands’ structures in the stadiums caused by such actions that should be taken in consideration in the course of design. Therefore, it is necessary to develop appropriate recommendations. Based on the developed recommendations, analysis of stadium structures for dynamic loads caused by the audience movement was performed in the time domain by direct integration of motion equation using certified software package Lira 10.4. It was obtained that the dynamic human-comfort level in the grandstands and in the under-grandstand facilities was ensured. Recommendations were made based on the analysis of international and Russian standard technical documents, generalization of available experience in design, construction, and operation of such objects, including similar unique large span structures. Obtained accelerations of under-grandstand facilities were analyzed in accordance with the construction standards SN 2.2.4/2.1.8.566-96. It was revealed that the limit values for some structure points have been exceeded.

Response control of cable-stayed arch bridge using modified hanger system

2020 ◽  
Vol 26 (23-24) ◽  
pp. 2316-2328 ◽  
Author(s):  
Salar Farahmand-Tabar ◽  
Majid Barghian
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Performance ◽  
Tensile Load ◽  
Comfort Level ◽  
Human Comfort ◽  
Response Control ◽  
Arch Bridge ◽  
The Stability ◽  
Cable Forces ◽  
And Control

Vertical or inclined cables which are placed in bridges as a hanger system affect the dynamic performance of bridges. Inclined hangers can be used instead of vertical hangers to improve the stability of the bridge aerodynamically. However, inclined hangers are susceptible to fatigue more than vertical ones. Considerable signs of distress or slackness might be shown by some inclined hangers because of their location on the bridge. In this study, a cable-stayed arch bridge with vertical and inclined hangers has been compared to investigate the effect of hangers on the dynamic performance of the bridge. To reduce the internal cable forces and the probability of fatigue or force fluctuation in hangers, additional horizontal cables are applied on inclined hangers that transfer the tensile load from overstressed hangers to adjacent ones with lower forces. By modification, the results demonstrate the higher stiffness and human comfort level for the bridge that improve the dynamic behavior and control the responses of the bridge.

scholarly journals Dynamics of Nonlocal Rod by Means of Fractional Laplacian

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1933
Author(s):  
Vittorio Gusella ◽  
Giuseppina Autuori ◽  
Patrizia Pucci ◽  
Federico Cluni
Keyword(s):  
Fractional Laplacian ◽  
Free Vibrations ◽  
Dynamic Loads ◽  
Model Parameters ◽  
Local Response ◽  
Proposed Model ◽  
Fractional Models ◽  
Static And Dynamic Loads ◽  
The Difference ◽  
The Time Domain

The use of fractional models to analyse nonlocal behaviour of solids has acquired great importance in recent years. The aim of this paper is to propose a model that uses the fractional Laplacian in order to obtain the equation ruling the dynamics of nonlocal rods. The solution is found by means of numerical techniques with a discretisation in the space domain. At first, the proposed model is compared to a model that uses Eringen’s classical approach to derive the differential equation ruling the problem, showing how the parameters used in the proposed fractional model can be estimated. Moreover, the physical meaning of the model parameters is assessed. The model is then extended in dynamics by means of a discretisation in the time domain using Newmark’s method, and the responses to different dynamic conditions, such as an external load varying with time and free vibrations due to an initial deformation, are estimated, showing the difference of behaviour between the local response and the nonlocal response. The obtained results show that the proposed model can be used efficiently to estimate the response of the nonlocal rod both to static and dynamic loads.

Analysis and Calculation of Electromagnetic Torque for the Voltage Source Traction Motors

2013 ◽  
Vol 446-447 ◽  
pp. 672-677
Author(s):  
Xiao Yu Wu ◽  
Zhe Ming Chen ◽  
Ze Hao Huang
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Voltage Source ◽  
Electromagnetic Torque ◽  
Motor Speed ◽  
Traction Motor ◽  
Traction Motors ◽  
Vehicle System ◽  
Mathematical Formulas ◽  
The Time Domain

The traction motor installed on the high-speed train is powered by inverter. A large number of harmonics may appear when motor is operating. Then the motor speed generate oscillation and finally the dynamic characteristic is affected in vehicle system. In this paper, relied on the electromagnetism of traction motor, the mechanism about emerging harmonic torque is analyzed. In addition, based on the equivalent circuit, the method of calculating the parameters in harmonic circuit is proposed. Two mathematical formulas are also proposed to obtain the fundamental electromagnetic torque and the harmonic electromagnetic torque on traction motor. The time domain and frequency domain distributions of the torques are gained and analyzed. Finally a calculation example of traction motor harmonic torque was analyzed and calculated, and prepared for further study of harmonic torque impacting on vehicle system dynamic performance.

A Novel Acceleration/Deceleration Control Algorithm for High Precision Feed Motion System

2012 ◽  
Author(s):  
Kun Cao ◽  
Wanhua Zhao ◽  
Hui Liu ◽  
Xiaojun Yang ◽  
Jun Zhang
Keyword(s):  
Dynamic Performance ◽  
Tracking Error ◽  
Transient State ◽  
Servo Control ◽  
Cnc System ◽  
Motion System ◽  
Servo Control System ◽  
Dynamic Precision ◽  
Transient Error ◽  
The Time Domain

The feed motion dynamic precision is determined by the properties of the CNC system, the servo control system and the mechanical structure. The Acceleration/Deceleration Control (ADC) in CNC system is widely used to smooth the motion trajectory, so as to reduce transient error caused by vibration. The performance of various ADC algorithms differ significantly, which indicates the importance of developing more effective ADC algorithm. In this paper a novel ADC algorithm called “Asymmetric Double S-shape type Algorithm” is introduced and validated by detailed mathematic deduction, and then its dynamic performance is compared with that of traditional ADC algorithms in both the time domain and frequency domain. The analytical and simulation results demonstrated that, the proposed novel ADC algorithm has notably advantage over the traditional ones in reducing the tracking error in both transient state and steady state, hence is capable of fundamentally improving the feed motion dynamic precision.

scholarly journals Validity of the ACTS Intimate Partner Violence Screen in Antenatal Care: A Cross Sectional Study

2021 ◽  
Author(s):  
K Hegarty ◽  
J Spangaro ◽  
M Kyei-Onanjiri ◽  
J Valpied ◽  
J Walsh ◽  
...  
Keyword(s):  
Intimate Partner Violence ◽  
Partner Violence ◽  
Screening Tool ◽  
Intimate Partner ◽  
Comfort Level ◽  
National Standard ◽  
Response Format ◽  
Reference Standard ◽  
Predictive Values ◽  
Frequency Scale

Abstract Background: Intimate partner violence (IPV) is a major public health problem with harmful consequences. In Australia, there is no national standard screening tool and screening practice is variable across states. The objectives of this study were to assess in the antenatal healthcare setting: i) the validity of a new IPV brief screening tool and ii) women’s preference for screening response format, screening frequency and comfort level.Methods: 1,067 antenatal patients in a major metropolitan Victorian hospital in Australia completed a paper-based, self-administered survey. The survey included four screening items about whether they were Afraid/Controlled/Threatened/ Slapped or physically hurt (ACTS) by a partner or ex-partner in the last 12 months; and the Composite Abuse Scale (reference standard). The ACTS screen was presented firstly with a binary yes/no response format and then with a five-point ordinal frequency format from ‘never’ (0) to ‘very frequently’ (4). The main outcome measures were test statistics of the four-item ACTS screening tool (sensitivity, specificity, predictive values, and area under the curve) against the reference standard and women’s screening preferences.Results: Twelve-month IPV prevalence varied depending on the ACTS response format with 8% (83) positive on ACTS yes/no format, 12.8% (133) positive on ACTS ordinal frequency format and 10.5% (108) on the reference Composite Abuse Scale. Overall, the ACTS screening tool demonstrated clinical utility for the ordinal frequency format (AUC, 0.80; 95% CI = 0.76 to 0.85) and the binary yes/no format (AUC, 0.74, 95% CI = 0.69 to 0.79). The frequency scale (66%) had greater sensitivity than the yes/no scale (51%). The positive and negative predictive values were 56% and 96% for the frequency scale and 68% and 95% for the yes/no scale. Specificity was high regardless of screening question response options. Half (53%) of the women categorised as abused preferred the yes/no scale. Around half of the women (48%, 472) thought health care providers should ask pregnant women about IPV at every visit.Conclusions: The four-item ACTS tool (using the frequency scale and a cut-off of one on any item) is recommended for written self-administered screening of women to identify those experiencing IPV to enable first-line response and follow-up.

Human Body as an Inconstant Heat Source and Its Relation to Clothes Insulation: Part 2—Experimental Investigation Into Dynamics of the Source

1960 ◽  
Vol 82 (1) ◽  
pp. 103-112 ◽  
Author(s):  
A. S. Iberall
Keyword(s):  
Thermal Power ◽  
Feedback System ◽  
Step Function ◽  
Activity Level ◽  
Comfort Level ◽  
Power Oscillations ◽  
Mode Of Operation ◽  
The Time Domain ◽  
Survival Mode ◽  
Error Indicators

Quantitative measurement on the human in the so-called evaporative, vasomotor, and metabolic control regimes has revealed frequency spectrum of sustained thermal power oscillations with approximate periods of 2, 7, 35 min, and 3 1/2 hr independent of the regime. Step function adjustments take place with a time constant of about 7 min. It is believed that the 3 1/2 hr cycle represents the shortest equilibrium cycle. The hypothesis that it might be possible to measure the resistance of clothing as an ohmic relation among time-averaged equilibrium values, and for a specific mode of operation of the system has now been put in rational context in the time domain. Two equilibrium modes of the human system were explored. The active mode of operation of the system, to which the resistance concept of clothes is most applicable, is as a feedback system in which the extremities are used as error indicators of deviations from a comfort level set point. In response to deviations, the human feeds back a signal to generate an activity level in which only internal work—immediately degraded into heat—is done to maintain the comfort level. This is referred to as the comfort mode of operation of the system. Another “survival” mode of operation of the system is also described.

Studies on the Dynamic Performance of a Spur Gear With Hollow Teeth

1992 ◽  
Author(s):  
A. Ramamohana Rao ◽  
B. Srinivasulu
Keyword(s):  
Damping Ratio ◽  
Dynamic Performance ◽  
Spur Gear ◽  
Dynamic Loads ◽  
Response Analysis ◽  
Spur Gears ◽  
Contact Ratio ◽  
Mesh Stiffness ◽  
Direction Parallel ◽  
Gear Teeth

Abstract Performance of spur gears largely depends on the magnitude and nature of variation of dynamic loads occuring between mating teeth. Variable tooth mesh stiffness is one of the primary sources causing parametric excitations resulting in dynamic loads. The usual method of varying the mesh stiffness to reduce dynamic loads is to use high contact ratio and profile modified gears. In this paper, a new type of tooth design to improve the dynamic performance of spur gears is presented. In this, a through hole is drilled in each tooth in a direction parallel to the gear axis. The diameter of the hole and its position on the tooth centre line are variable. Such a gear is called a hollow gear. Dynamic analysis is carried out for the mesh of hollow pinions mating with solid gears. The results are compared with solid pinions (no holes in teeth) meshing with solid gears. Finite element method is used for the analysis. For estimation of the dynamic load variation in hollow-solid and solid-solid gear meshes, a model incorporating the varying mesh stiffness and damping of gear teeth is used. Governing differential equations are solved using unconditionally stable Newmark-beta algorithm. The dynamic loads obtained are used as an input time varying loads for the determination of dynamic fillet and hole stress response of solid and hollow gear teeth whichever is applicable. Modal superposition technique is used for transient response analysis. The study shows that for the same damping ratio, dynamic loads in hollow-solid meshes are nearly the same as in a solid-solid mesh. In reality, the dynamic loads in a hollow-solid mesh are less than a solid-solid mesh due to its inherent higher material damping.

Simulation Research of CVT Variable Fertilization Control System

2013 ◽  
Vol 336-338 ◽  
pp. 614-618
Author(s):  
Chun Ying Liang ◽  
Qian Hui Xu ◽  
Jian Wei Ji ◽  
Ling Ling Zhu
Keyword(s):  
Control System ◽  
Performance Index ◽  
Pid Controller ◽  
Dynamic Performance ◽  
Variable Rate ◽  
Simulation Research ◽  
Analysis And Evaluation ◽  
The Time Domain ◽  
Magnitude Increase ◽  
Steady State Performance

Using MATLAB to establish emulation model of variable rate fertilization control system, using the Z-N method to setting the system of PID parameters, emulation of the system has without PID controller and PID controller, analysis and evaluation of the system dynamic performance index and steady-state performance index. The emulation results shows that the system with PID controller, the maximum overshoot reduce, adjusting time short, improve the time domain dynamic index; phase margin increase, magnitude increase, improved the performance index of the frequency domain.

scholarly journals Dynamic performance of slender suspension footbridges under eccentric walking dynamic loads

2007 ◽  
Vol 303 (1-2) ◽  
pp. 239-254 ◽  
Author(s):  
Ming-Hui Huang ◽  
David P. Thambiratnam ◽  
Nimal J. Perera
Keyword(s):  
Dynamic Performance ◽  
Dynamic Loads
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