Analysis of an electrically actuated fractional model of viscoelastic microbeams

Bahraini, Seyed Masoud Sotoodeh,Eghtesad, Mohammad,Farid, Mehrdad,Ghavanloo, Esmaeal Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.5

The MEMS structures usually are made from silicon; consideration of the viscoelastic effect in microbeams duo to the phenomena of silicon creep is necessary. Application of the fractional model of microbeams made from viscoelastic materials is studied in this paper. Quasi-static and dynamical responses of an electrically actuated viscoelastic microbeam are investigated. For this purpose, a nonlinear finite element formulation of viscoelastic beams in combination with the fractional derivative constitutive equations is elucidated. The four-parameter fractional derivative model is used to describe the constitutive equations. The electric force acting on the microbeam is introduced and numerical methods for solving the nonlinear algebraic equation of quasi-static response and nonlinear equation of motion of dynamical response are described. The deflected configurations of a microbeam for different purely DC voltages and the tip displacement of the microbeam under a combined DC and AC voltages are presented. The validity of the present analysis is confirmed by comparing the results with those of the corresponding cases available in the literature.

Determinants of Firm Value

Syintia BAHRAINI,Endri ENDRI,Sugeng SANTOSO,Leni HARTATI,Sri Marti PRAMUDENA 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6

There are many factors that affect the firm value, both internal and external factors. These factors can directly or indirectly affect the firm value. This study aims to prove empirically the determinants of firm value as measured by using the Price to Book Value (PBV) in the food and beverage (F&B) industry listed on the Indonesia Stock Exchange (ISE). The estimated determinants include Total Asset Turnover (TATO), company size (SIZE), Current Ratio (CR), Return on Equity (ROE), and Debt to Equity Ratio (DER). The research method used is a panel data regression model with a sample of 17 companies in the F&B sector from 2015 to 2019. The results of the study conclude that the increase in the TATO, CR, and Size factors results in a decrease in firm value, while the impact of ROE and DER factors on the contrary causes PBV to increase. Taken together, all of the estimated determinants affect firm value. The practical implication of the research findings for the company is that if profitability increases, the increase in total debt can increase firm value. However, the use of debt must be allocated for investment in both current assets and fixed assets, if these assets are used efficiently to generate profits so that it has an impact on increasing company value.

Analysis of an electrically actuated fractional model of viscoelastic microbeams

Seyed Masoud Sotoodeh Bahraini,Mohammad Eghtesad,Mehrdad Farid,Esmaeal Ghavanloo 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.5

The MEMS structures usually are made from silicon; consideration of the viscoelastic effect inmicrobeams duo to the phenomena of silicon creep is necessary. Application of the fractional model of microbeams made from viscoelastic materials is studied in this paper. Quasi-static and dynamical responses of an electrically actuated viscoelastic microbeam are investigated. For this purpose, a nonlinear finite element formulation of viscoelastic beams in combination with the fractional derivative constitutive equations is elucidated. The four-parameter fractional derivative model is used to describe the constitutive equations. The electric force acting on the microbeam is introduced and numerical methods for solving the nonlinear algebraic equation of quasi-static response and nonlinear equation of motion of dynamical response are described. The deflected configurations of a microbeam for different purely DC voltages and the tip displacement of the microbeam under a combined DC and AC voltages are presented. The validity of the present analysis is confirmed by comparing the results with those of the corresponding cases available in the literature.

Large deflection of viscoelastic beams using fractional derivative model

Seyed Masoud Sotoodeh Bahraini,Mohammad Eghtesad,Mehrdad Farid,Esmaeal Ghavanloo 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.4

This paper deals with large deflection of viscoelastic beams using a fractional derivative model. For this purpose, a nonlinear finite element formulation of viscoelastic beams in conjunction with the fractional derivative constitutive equations has been developed. The four-parameter fractional derivative model has been used to describe the constitutive equations. The deflected configuration for a uniform beam with different boundary conditions and loads is presented. The effect of the order of fractional derivative on the large deflection of the cantilever viscoelastic beam, is investigated after 10, 100, and 1000 hours. The main contribution of this paper is finite element implementation for nonlinear analysis of viscoelastic fractional model using the storage of both strain and stress histories. The validity of the present analysis is confirmed by comparing the results with those found in the literature.

Neighbourhood morphology, genuine self-expression and place attachment, the case of Tehran neighbourhoods

Hossein Khosravi,Hossein Bahrainy,Shadi Omidvar Tehrani 서울시립대학교 도시과학연구원 2020 도시과학국제저널 Vol.24 No.3

In this paper, the neighbourhood’s morphology has been evaluated according to socio-behavioural aspects and sense of place. It seems that place attachment, social bonding, and total time residents spent in local spaces are highly determined by neighbourhood’s socio-behavioural dimensions, and in turn, neighbourhood’s morphological attributes have a great impact on socio-behavioural dimensions. To verify the hypothesis, 843 participants have been selected through Neyman allocation modelling from 5 morphologically representative neighbourhoods. The built-environment attributes were gathered through an objective method (GIS). Sense of place, meantime residents, spent in public spaces, socio-behavioural indicators, and a number of socio-demographic characteristics were collected by self-administered questionnaires. According to our analysis, high and middle-rise neighbourhoods, with low coverage massing, by providing plenty of wide, non-hierarchical, and inter-connected spaces, could ensure personal privacy, anonymity, and consequently autonomy, genuineness, and tendency to use neighbourhood spaces. In contrast, historic organic neighbourhoods with narrow hierarchical pathways and massing alongside them increase the level of social monitoring and conformity. Thus, policies that support mixed-use, connected street networks, plenty of shared open spaces, non- hierarchical network patterns, and smaller block sizes can be used by urban designers to promote neighbourhoods supporting residents’ psycho-social preferences.

Motor and Sensory Outcomes of Infantile Exotropia: A 10-Year Study (2008–2017)

Zhale Rajavi,Hamideh Sabbaghi,Narges Behradfar,Saeid Abdi,Razieh Bahraini,Bahareh Kheiri,Kourosh Sheibani 대한안과학회 2020 Korean Journal of Ophthalmology Vol.34 No.2

Purpose: We aimed to determine the long-term motor and sensory outcomes of patients with infantile exotropia. Methods: In this longitudinal retrospective (historical cohort) study, the records of 76 patients with infantile exotropia were Studied. Subjects with constant exotropia manifesting before the age of 1 year who were at least 5 years old at recruitment time between 2008 and 2017 were included. Results: The medical records of 26 patients were excluded due to not participating in follow-up examinations or having incomplete records. In total, 54 infantile exotropic patients (51.9% male) with a mean age of 11.1 ± 6.8 years and follow-up of 4.99 ± 3.58 years were studied. Postoperative sensory outcomes (central stereopsis [<60 sec/arc], peripheral fusion [60–3,000 sec/arc], and non-stereopsis [>3,000 sec/arc]) were observed in 38.9%, 38.9%, and 21.2% of patients, respectively. In terms of postoperative motor outcomes, 69%, 24%, and 7% were achieved as orthophoria, residual exotropia, and consecutive esotropia, respectively. Patients with a higher surgical age (p = 0.022) and better visual acuity (p = 0.004) had significantly better sensory outcomes, while higher preoperative deviation resulted in more suppression (p = 0.039, rs = 0.218). Conclusions: With rates of 69% for motor success and 78.8% for sensory success, surgical outcomes of infantile exotropic patients seems to be favorable. Further studies are recommended to verify our findings.