scholarly journals Investigation on Damping Characteristics of Hydrostatic Bearing Film by Using Scale Method

2021 ◽  
Author(s):  
Sheng-Yen Hu ◽  
Wen-Chou Chen ◽  
Chien-Hsun Wang ◽  
Hsin-Ming Fu ◽  
Yuan Kang
Keyword(s):  
Damping Ratio ◽  
Resonant Peak ◽  
Test Results ◽  
Scaling Method ◽  
Single Degree Of Freedom ◽  
Hydrostatic Bearing ◽  
Damping Characteristics ◽  
Mass Spring ◽  
The Impact

Abstract The resonant peaks can be suppressed by damping, those effects is dependent on damping ratio of system. In this paper, we propose a scaling method to evaluate the damping ratio of hydrostatic bearings for the data from model test. This method fits specifically for the overdamping of all hydrostatic bearing. This is direct and the easiest method to obtain the damping characteristics of oil film for the lowest band before the first resonant peak. The frequency responses of acceleration per force for a single-degree-of-freedom mass-spring-damper model is used to generate the evaluation scales for the damping ratios of the modal test results of worktable mounting on hydrostatic bearing. The case study for experimental results of the impact response are evaluated for damping ratio of the hydrostatic film by these method. Furthermore, using this scaling method, the influences of three types of compensations on the damping ratio of a hydrostatic bearing are compared. The results reveal that the constant flow has the largest damping ratio, and the capillary restrictor has the smallest one.

Impact of Inclusion in General Physical Education on Students Without Disabilities

2003 ◽  
Vol 20 (3) ◽  
pp. 230-245 ◽  
Author(s):  
Iva Obrusníková ◽  
Hana Válková ◽  
Martin E. Block
Keyword(s):  
Physical Education ◽  
Case Study Research ◽  
Test Results ◽  
Attitude Inventory ◽  
Direct Support ◽  
General Physical ◽  
In The Beginning ◽  
General Physical Education ◽  
The Impact

The purpose of this investigation was to evaluate the impact of including a student who uses a wheelchair and is given no direct support in a 4th grade general physical education (GPE) class on students without disabilities. Using an evaluate case study research method, data were collected in the beginning and end of a 2-week GPE volleyball unit from 2 intact elementary school classes using 2 attitude inventories, volleyball skills, and knowledge test. Results indicated no significant class difference in volleyball skill and knowledge acquisitions. Overall, attitudes toward including a student with a disability tended to be positive in both classes. In addition, there was no significant time difference within the classes on either attitude inventory.

scholarly journals THE IMPACT OF TECHNIQUES AND TRANSLATION IDEOLOGY ON THE CLARITY OF PRAGMATIC MEANINGS TRANSLATION OF THE QUR’ANIC IMPERATIVE VERSES

2018 ◽  
Vol 7 (3) ◽  
pp. 676
Author(s):  
Mohamad Zaka Al Farisi
Keyword(s):  
Test Results ◽  
Evaluative Study ◽  
Embedded Case Study ◽  
The Impact

One of the stylistic features of the Qur’an is the existence of imperative verses that have certain pragmatic meanings. The feature often makes the Indonesian translation of these verses complex. This is mainly related to the fulfillment of the aspect of clarity in translation. This study aims to reveal the subtle translation of imperative verses of the Qur’an with certain pragmatic meanings. This descriptive-evaluative study used the design of embedded case study because the findings apply only to the imperative verses that serve as the research sample. The sample of the study was chosen purposively from the Qur’anic verses that contain imperative speech. They are imperative verses that have certain pragmatic meanings, such as al-tahdid (threatening), al-ihanah (humiliating), and so forth. The focus of the study is on the subtle translation of imperative verses contained in the translation version by UMT. In general, based on the responses of respondents and the test results, the translations of imperative verses by UMT produce acceptable clarity.

Analysis of Dynamic Response of Simply-Supported Girder Bridge in High-Speed Railway Based on the Moving Rows Mass-Spring Model

2012 ◽  
Vol 193-194 ◽  
pp. 919-924
Author(s):  
Jin Feng Wu ◽  
Zhi Jun Zhang ◽  
Xiao Zhen Li
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Spring Model ◽  
Simply Supported ◽  
Mass Spring Model ◽  
Girder Bridge ◽  
Set Up ◽  
Mass Spring ◽  
The Impact ◽  
Bridge System

The vibration theory of beam and D’Alembert principle are used to set up vehicle-bridge system for a simply-supported girder bridge under the moving rows mass-spring model. The kinematic equations of vehicle and bridge are derived separately. And with the force balanced relationship and the displacement compatibility conditions between wheels and rail, the equations of vehicle-bridge system are established. A calculating program is complicated with MATLAB language and solved by Newmark-β method. Results show that the effect of the damping ratio on the impact factor is significant and running speed of the vehicle is one of the main actors resulting in vibration of the system.

scholarly journals Competitiveness of seafood enterprises: the case study of Ba-Ria-Vung-Tau province, Vietnam

2020 ◽  
Vol 164 ◽  
pp. 06001
Author(s):  
Aí Huu Tran
Keyword(s):  
Value Chain ◽  
Statistical Significance ◽  
Test Results ◽  
Research Model ◽  
Competition Theory ◽  
Legal Factor ◽  
Seafood Processing ◽  
The Impact ◽  
Traditional Competition

This study aims to identify and measure the impact on the Competitive capability of frozen seafood processing enterprises in BR-VT province. Research access tocompetitiveness is based on competency theory, different from previous domestic studies primarily approaching competitiveness based on traditional competition theory and value chain theory. The research model consists of 9 factors. The study was conducted with 356 survey samples of 76 frozen seafood processing enterprises, surveyed through a questionnaire.Data analysis through SPSS 24.0. The test results have 8 accepted hypothesis, the highest impact factor is the ability to access and innovate technology with β = 0.3328 (p = 0.000) and the lowest is local infrastructure factorwith β = 0.067 (p = 0.042), and Policy and Legal Factor with β = - 0.038 (p = 0.249), there is not statistical significance should not be accepted.

scholarly journals The Impact of Stakeholders on Schools for Improving Students’ Performance: The Case of Israeli Students Performance in the PISA Test

2020 ◽  
Vol 4 (4) ◽  
pp. p1
Author(s):  
Rawia Ashqar ◽  
Loureen D. Haddad
Keyword(s):  
Education System ◽  
Test Results ◽  
The Media ◽  
The Government ◽  
The Impact

This study examines the pressure employed by stakeholders on the management of schools and the insertion of reforms in the education system. The article analyzes the case-study of Israeli stakeholders’ reaction to the Israeli students’ performance in the PISA test. The argument of the article is that the media in Israel deals extensively with the performance of Israeli students in these tests, and the media turns into the main source that feeds Israeli parents knowledge of the test results. Consequently, pressure is employed by parents in particular on the government and schools to do all in their capacity to improve the results and to raise Israel’s ranking on these international tests. As a result, the government has created a commission to reform the education system. Following the implementation of the commission’s recommendations, Israel managed during the last two decades to improve the performance of Israeli students in the PISA test.

Investigation of Granular Damping in Transient Vibrations Using Hilbert Transform Based Technique

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
X. Fang ◽  
H. Luo ◽  
J. Tang
Keyword(s):  
Hilbert Transform ◽  
Damping Ratio ◽  
Temporal Frequency ◽  
Nonlinear Damping ◽  
Vibration Level ◽  
Damping Characteristics ◽  
The Difference ◽  
The Hilbert Transform ◽  
Granular Damping ◽  
The Impact

Granular damping results from a combination of energy dissipation mechanisms including the impact and the friction between the vibrating structure and granules and among the granules. Although simple in concept, granular damping is very complicated and its performance depends on a number of factors, such as vibration level, granular material properties, packing ratio, etc. In this study, free vibration experiments are conducted on a cantilevered beam incorporated with granular damping. A signal analysis approach based on the Hilbert transform (HT) is then employed to identify the nonlinear damping characteristics from the acquired responses, such as the dependency of the natural frequency and damping ratio on the vibration level. This HT based analysis can produce an effective temporal-frequency amplitude∕energy analysis, which provides us with physical insights of the nonlinear transient response. A direct comparison between the granular damping and the impact damping (with single impactor to dissipate vibratory energy) is performed to highlight the difference between these two and the advantages of granular damping. Finally, the validity of the proposed approach is also examined by the successful prediction of vibration response using the extracted granular damping characteristics.

scholarly journals Effects of Spring and Damper Elements in Aircraft Landing Gear Dynamics

2020 ◽  
Vol 8 (5) ◽  
pp. 4265-4269
Keyword(s):  
Shock Absorber ◽  
Impact Force ◽  
Landing Gear ◽  
Damping Coefficient ◽  
Aircraft Landing ◽  
Aircraft Landing Gear ◽  
Spring Coefficient ◽  
Mass Spring ◽  
The Impact

In this study a typical Aircraft Landing Gear with shock absorber was modeled a Mass-Spring-Damper System. Basic components of the system were explained. The equations of the model was presented. Aircraft Landing Gear was also modeled in Matlab/Simulink for a given set of aircraft parameters. A case study for an Aircraft Landing Gear was solved and results were presented. Results included the variation of spring (k1 and k2 ) and damping coefficient (b) in a given interval to show their effects on the impact force and displacement of landing gear as main outputs to consider. Effect of damping coefficient (b) on impact force was found to be highest (3.76%), spring coefficient (k1 ) effect is moderate (2.29%), and spring coefficient (k2 ) is lower (0.97%), for a change of ±10% of coefficients.

The Effect of Dual-Rate Suspension Damping on Vehicle Response to Transient Road Inputs

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
T. P. Waters ◽  
Y. Hyun ◽  
M. J. Brennan
Keyword(s):  
Damping Ratio ◽  
Peak Acceleration ◽  
Acceleration Response ◽  
Natural Period ◽  
Single Degree Of Freedom ◽  
Vehicle Suspensions ◽  
Damping Characteristics ◽  
Potential Benefits ◽  
Approximate Expressions

The acceleration response of road vehicles to shock inputs from road irregularities such as bumps and hollows is an important consideration in the design of vehicle suspensions and damping characteristics, in particular. In this paper, the influence of the damper on the shock response of a simple vehicle model is considered. An analysis is presented of a single degree-of-freedom model subjected to a transient displacement input. Simple approximate expressions are given for the peak acceleration during an impulse of both short and long durations compared to the natural period, from which the role of the damper is clearly apparent. For impulses of short duration the peak acceleration occurs during the impulse and is shown to be approximately proportional to the damping ratio. Corollary to this, the peak acceleration can be reduced by switching the damper to a lower value during the impulse. The potential benefits of doing so are illustrated through numerical simulation, and a simple formula is given for the maximum possible reduction in peak acceleration. The results are also contrasted with those of a conventional dual-rate automotive damper model. The switchable damper is found to offer sufficient benefit to warrant further investigation.

Biomechanical Efficiency of Wrist Guards as a Shock Isolator

2005 ◽  
Vol 128 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Il-Kyu Hwang ◽  
Kyu-Jung Kim ◽  
Kenton R. Kaufman ◽  
William P. Cooney ◽  
Kai-Nan An
Keyword(s):  
Energy Absorption ◽  
Impact Force ◽  
Damping Ratio ◽  
Linear Mass ◽  
Human Subject Testing ◽  
Wrist Guard ◽  
The Common ◽  
Mass Spring ◽  
The Impact

Despite the use of wrist guards during skate- and snowboard activities, fractures still occur at the wrist or at further proximal locations of the forearm. The main objectives of this study were to conduct a human subject testing under simulated falling conditions for measurement of the impact force on the hand, to model wrist guards as a shock isolator, to construct a linear mass-spring-damper model for quantification of the impact force attenuation (Q-ratio) and energy absorption (S-ratio), and to determine whether wrist guards play a role of an efficient shock isolator. While the falling direction (forward and backward) significantly influenced the impact responses, use of wrist guards provided minimal improvements in the Q- and S-ratios. It was suggested based on the results under the submaximal loading conditions that protective functions of the common wrist guard design could be enhanced with substantial increase in the damping ratio so as to maximize the energy absorption. This would bring forth minor deterioration in the impact force attenuation but significant increase in the energy absorption by 19%, which would help better protection against fall-related injuries of the upper extremity.

scholarly journals Towards reduction in bias in epidemic curves due to outcome misclassification through Bayesian analysis of time-series of laboratory test results: Case study of COVID-19 in Alberta, Canada and Philadelphia, USA

2020 ◽  
Author(s):  
Igor Burstyn ◽  
Neal D. Goldstein ◽  
Paul Gustafson
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Series Data ◽  
Clinical Settings ◽  
Test Results ◽  
Bias Analysis ◽  
Laboratory Test Results ◽  
Misclassification Errors ◽  
The Impact

The aim of our work was to better understand misclassification errors in identification of true cases of COVID-19 and to study the impact of these errors in epidemic curves. We examined publically available time-series data of laboratory tests for SARS-CoV-2 viral infection, the causal agent for COVID-19, to try to explore, using a Bayesian approach, about the sensitivity and specificity of the PCR-based diagnostic test. Data originated from Alberta, Canada (available on 3/28/2020) and city of Philadelphia, USA (available on 3/31/2020). Our analysis revealed that the data were compatible with near-perfect specificity but it was challenging to gain information about sensitivity (prior and posterior largely overlapped). We applied these insights to uncertainty/bias analysis of epidemic curves into jurisdictions under the assumptions of both improving and degrading sensitivity. If the sensitivity improved from 60 to 95%, the observed and adjusted epidemic curves likely fall within the 95% confidence intervals of the observed counts. However, bias in the shape and peak of the epidemic curves can be pronounced, if sensitivity either degrades or remains poor in the 60-70% range. In the extreme scenario, hundreds of undiagnosed cases, even among tested, are possible, potentially leading to further unchecked contagion should these cases not self-isolate. The best way to better understand bias in the epidemic curves of COVID-19 due to errors in testing is to empirically evaluate misclassification of diagnosis in clinical settings and apply this knowledge to adjustment of epidemic curves, a task for which the Bayesian method we presented is well-suited.

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