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Dimensional analysis of base-isolated buildings to near-fault pulses
Denis Istrati,Constantine C. Spyrakos,Panagiotis G. Asteris,Eleni Panou-Papatheodorou 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.1
In this paper the dynamic behavior of an isolated building subjected to idealized near-fault pulses is investigated. The building is represented with a simple 2-DOF model. Both linear and non-linear behavior of the isolation system is considered. Using dimensional analysis, in conjunction with closed form mathematical idealized pulses, appropriate dimensionless parameters are defined and self-similar curves are plotted on dimensionless graphs, based on which various conclusions are reached. In the linear case, the role of viscous damping is examined in detail and the existence of an optimum value of damping along with its significant variation with the number of half-cycles is shown. In the nonlinear case, where the behavior of the building depends on the amplitude of the excitation, the benefits of dimensional analysis are evident since the influence of the dimensionless Π-terms is easily examined. Special consideration is given to the normalized strength of the non-linear isolation system that appears to play a complex role which greatly affects the response of the 2-DOF. In the last part of the paper, a comparison of the responses to idealized pulses between a linear fixed-base SDOF and the respective isolated 2-DOF with both linear and non-linear damping is conducted and it is shown that, under certain values of the superstructure and isolation system characteristics, the use of an isolation system can amplify both the normalized acceleration and displacement of the superstructure.
A political–institutional explanation of environmental performance in Latin America
Denis Rey,Joshua Ozymy 한국외국어대학교 국제지역연구센터 2019 International Area Studies Review Vol.22 No.4
This research utilizes the 2010 Environmental Performance Index to examine how electoral rules affect environmental performance in 20 Latin American democracies. Using supporting timeseries analysis with dependent variables for habitat protection, particulate matter, and carbon dioxide emissions from 2000 to 2008, our study finds that proportionality and party systems influence environmental performance in the region. Results show that representation impacts ecosystem vitality more so than public health. We account for this gap by arguing that levels of political representation influence the allocation of public and private goods which, in turn, help determine environmental outcomes. Our findings do not always paint a consistent picture, which may be attributed to the difficulties of operationalizing complex concepts such as environmental performance within and across countries and examining how these relationships change over time. Additional research is warranted to tease out these relationships.
Denis USHAKOV 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.8
The performance appraisal system is defined as general satisfaction with the performance appraisal system. It is used to assess employees’ attitudes towards the fairness of the appraisal system, as well as their satisfaction with their knowledge of the appraisal system. This study aims to investigate the relationship between performance appraisal satisfaction and employee performance with equity as a mediator of this relation. There is limited research that studied the mediating effect of performance appraisal on the relationship between organizational justice and work performance. The research implemented the quantitative methodology throughout distributing questionnaires using google forms for data collection. Only 181 respondents out of 221 respondents answered the questionnaires. The data had been analyzed using the AMOS tool for performing structural equation modeling (SEM) analysis to validate the mediating relationship of equity and justice on the relationship between performance appraisals satisfaction and employees’ performance. The results indicated that achieving organizational fairness and equity in the workplace can be done by the implementation of performance appraisal satisfaction, which can lead to higher productivity in the workplace, whichin turn will enhance the organization’s image among its competitors.
Lateral Driving Envelope Protection Using Cascade Control
Denis Efremov,Yehor Zhyliaiev,Bohdan Kashel,Toma? Hani? 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
The steer-by-wire technology opens a possibility to create new advanced driver assistant systems. This work proposes a control structure that keeps the lateral vehicle dynamics in predefined stability boundaries and prevents the dominant sliding motion. We intentionally employed a cascade control law design suited for embedded platforms, often with low computational capacity. The proposed control hierarchical architecture is heavily inspired by aerospace domain solution, the flight envelope protection algorithms, which are still used in modern civil aircraft. The vehicle lateral acceleration is selected as the control system reference signal, commanded by a driver. The controller tracks such reference signal while respecting the driving envelope and vehicle operation safety limits. Several driving experiments were conducted to evaluate the proposed control structure in the statistical sense. The comparison with solution based on model predictive control framework and baseline vehicle without any assistance system is presented. Performed experiments were evaluated based on objective vehicle performance, like lap time and a number of collisions, combined with a human driver’s subjective evaluation. Experiments clearly show the incoherence of results and biased of skilled drivers. The objectively better vehicle performance, faster lap time with fewer collisions, received a lower subjective evaluation from experienced drivers used to current driving style.