Analysis and Implementation of High Step-Up DC/DC Convertor with Modified Super-Lift Technique

Rezvan Fani,Ebrahim Farshidi,Ehsan Adib,Abdolnabi Kosarian 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

In this paper, a new high step up DC/DC converter with a modified super-lift technique is presented. The coupled inductor technique is combined with the super-lift technique to provide a tenfold or more voltage gain with a proper duty cycle and a low turn ratio. Due to a high conversion ratio, the voltage stress on the semiconductor devices is reduced. As a result, low voltage ultra-fast recovery diodes and low on resistance MOSFET can be used, which improves the reverse recovery problems and conduction losses. This converter employs a passive clamp circuit to recycle the energy stored in the leakage inductance. The proposed convertor features a high conversion ratio with a low turn ratio, low voltage stress, low reverse recovery losses, omission of the inrush currents of the switch capacitor loops, high efficiency, small volume and reduced cost. This converter is suitable for renewable energy applications. The operational principle and a steady-state analysis of the proposed converter are presented in details. A 200W, 30V input, 380V output laboratory prototype circuit is implemented to confirm the theoretical analysis.

Late Presentation of Anal Canal Duplication in Adults: A Series of Four Rare Cases

Rezvan Mirzaei,Bahar Mahjubi,Mina Alvandipoor,Mohammad Yasin Karami 대한대장항문학회 2015 Annals of Coloproctolgy Vol.31 No.1

Anal canal duplication (ACD) is a very rare condition, especially in adults. Four cases in adults are reported. In three cases, the orifice of duplication was located behind the native anus, and in one case, it was located anteriorly. In all cases, no communication between the anal canal and the tract of duplication was noted. Complete removals of the duplications were done through a perineal approach. Histology showed fibro-muscular tissue lined with a squamous epithelium. The postoperative courses were uneventful.

Mother Tongue, a Necessary Step to Intellectual Development

( Rezvan Noormohamadi ) 범태평양응용언어학회 2008 범태평양응용언어학회지 Vol.12 No.2

Intellectual (cognitive) development, the emergence of increasingly sophisticated forms or levels of understanding, reasoning, and rationality is an ongoing process of reflection, coordination, and social interaction that begins in early childhood and continues, at least in some cases, long into adulthood (Moshman, 2003). In this process, language is a primary tool in the entire life. However, it is not to say that thinking (as an intellectual ability) cannot take place without language (Munn, 1951), but rather mostly, thinking is mediated by language and thus develops to a much higher level of sophistication. The intimate link between language and cognitive development forms the core of the present article. It focuses on the important contribution of mother tongue in the process of cognitive development. Two major theories of development: Piaget and Vygotskys` views are investigated in relation to language. It is concluded that, although thought is the base, language intellectualizes it to a great deal.

Satisfaction with Hearing Aids among Aged Patients with Different Degrees of Hearing Loss and Length of Daily Use

Rezvan Dashti,Farzad Faraji Khiavi,Seyyed Jalal Sameni,Arash Bayat 대한청각학회 2015 Journal of Audiology & Otology Vol.19 No.1

Background and Objectives: The evaluation of subjective benefits and positive effects of hearing aids in daily is important for measuring the treatment outcome. The aim of this project was to investigate the degree of satisfaction of aged users with their hearing aids using the Satisfaction with Amplification in Daily Life (SADL) scale, which emphasizes non-auditory factors contributing to satisfaction as well as benefit. Subjects and Methods: The Persian version of SADL scale was completed by 40 patients who received monaural hearing aid fitting at south of the Iran from December 2013 and March 2014. SADL subscales of the SADL were evaluated according to the type and degree of hearing loss, the pure tone audiogram pattern and shape and type of the hearing aid. Results: The results associated with the SADL subscales revealed a greater satisfaction associated with the Positive Effect and Service and Costs subscales. Subjects with different degree of hearing loss were very satisfied in terms of positive effect subscale. Conclusions: Participants reported a considerable level of satisfaction with their hearing aids. Appropriate guidance for using hearing aids and spending more time for counseling can improve the satisfaction level of this age group.

An Overview on Wound Dressings and Sutures Fabricated by Electrospinning

Rezvan Mohamadinooripoor,Soheila Kashanian,Elham Arkan 한국생물공학회 2023 Biotechnology and Bioprocess Engineering Vol.28 No.1

Electrospinning is simple and cost-effective technique for micro/nano-fibers production that have emerged recently. Electrospun fibers have a wide variety of applications. They can provide ideal wound dressings, and so exhibit significant potential in production of therapeutic loaded sutures. Wound treatments have a huge commercial enterprise and the demand of them are increasing day by day. Thus, it seems essential to summarize wound dressings and sutures which were prepared using electrospinning technique. In this review, we will investigate the wound healing processes and the process of electrospinning and also the effective parameters of the process. Future directions of this compilation will explore kinds of electrospun wound dressing and sutures.

ANNIHILATOR GRAPHS OF COMMUTATOR POSETS

( Rezvan Varmazyar ) 호남수학회 2018 호남수학학술지 Vol.40 No.1

Let P be a commutator poset with Z(P) its set of zero-divisors. The annihilator graph of P, denoted by AG(P), is the (undirected) graph with all elements of Z(P) | {0} as vertices, and distinct vertices x, y are adjacent if and only if ann(xy) ≠ ann(x) ∪ ann(y). In this paper, we study basic properties of AG(P).

Optimization of Extraction Process of Bioactive Compounds from Bene Hull Using Subcritical Water

Rezvan Shaddel,Abdolmajid Maskooki,Mohammad Hossein Haddad-Khodaparast,Sodeif Azadmard-Damirchi,Morteza Mohamadi,Bahram Fathi-Achachlouei 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.5

Bene hull contains antioxidant components. Optimum conditions for bioactive compound extractionprocesses from Bene hull using subcritical water withresponse surface methodology (RSM) were obtained. Temperature (110-200oC), processing time (30-60 min),and the water to Bene hull ratio (10:1-50:1) were theinvestigated factors. The optimal conditions for maximizingthe antioxidant activity were 196.8oC for 52.6 min and aratio of 43.6:1 for water to Bene hull. Under these conditions,the amount of polyphenolic compounds, the reductionpower (RP) (EC50), and the DPPH free radical scavengingactivity (RSA) (EC50) were predicted to be 2,284 mg ofgallic acid/100 g of Bene hull, 0.2002 mg/mL, and 0.6284mg/mL, respectively. HPLC analysis was used to identifythe main phenolic compounds. The subcritical waterextraction technique could be used as a beneficial methodto obtain bioactive compounds from Bene hull.

Association of Amplitude and Stability of Circadian Rhythm, Sleep Quality, and Occupational Stress with Sickness Absence among a Gas Company Employeesd-A Cross Sectional Study from Iran

Rezvan Zare,Alireza Choobineh,Sareh Keshavarzi 한국산업안전보건공단 산업안전보건연구원 2017 Safety and health at work Vol.8 No.3

Background: The present study was carried out to assess the relationship between sickness absence and occupational stress, sleep quality, and amplitude and stability of circadian rhythm as well as to determine contributing factors of sickness absence. Methods: This cross sectional study was conducted on 400 randomly selected employees of an Iranian gas company. The data were collected using Pittsburgh sleep quality index, Karolinska sleepiness scale, circadian type inventory, and Osipow occupational stress questionnaires. Results: The mean age and job tenure of the participants were 33.18 5.64 years and 6.06 4.99 years, respectively. Also, the participants had been absent from work on average 2.16 days a year. According to the results, 209 participants had no absences, 129 participants had short-term absences, and 62 participants had long-term absences. The results showed a significant relationship between short-term absenteeism and amplitude of circadian rhythm [odds ratio (OR)¼ 6.13], sleep quality (OR ¼ 14.46), sleepiness (OR ¼ 2.08), role boundary (OR ¼ 6.45), and responsibility (OR ¼ 5.23). Long-term absenteeism was also significantly associated with amplitude of circadian rhythm (OR ¼ 2.42), sleep quality (OR ¼ 21.56), sleepiness (OR ¼ 6.44), role overload (OR ¼ 4.84), role boundary (OR ¼ 4.27), and responsibility (OR¼ 3.72). Conclusion: The results revealed that poor sleep quality, amplitude of circadian rhythm, and occupational stress were the contributing factors for sickness absence in the study population.

On the Relationship Between Language Learning Strategies and Foreign Language Anxiety

( Rezvan Noormohamadi ) 범태평양응용언어학회 2009 범태평양응용언어학회지 Vol.13 No.1

Previous research studies have shown language anxiety to be related with broad-based indices of language achievement, like course grade. However, to date, the potential link between foreign language anxiety and language learning strategies has not been empirically investigated. This study is an attempt to identify the relationship between language anxiety and strategy use. It reports on a survey of language learning strategies used by high-anxious and lowanxious learners. Generally, significant negative correlation obtained between levels of language anxiety and strategy use. In the meantime, t-test revealed significant difference between high-anxious and low-anxious groups on the level of use of strategies. That is, the more anxious the students are, the less frequently they use strategies. Further, the result showed that among students with high anxiety metacognitive and memory strategies were the most used, while compensation and affective strategies were the least. Less anxious students reported using metacognitive and social strategies as the most, on the other hand, memory, and affective strategies as the least ones. This study discusses these findings, suggests possible questions for future research, and makes implications for increasing foreign language learning.

On graded $(m, n)$-closed submodules

Rezvan Varmazyar 대한수학회 2023 대한수학회논문집 Vol.38 No.4

Let $A$ be a $G$-graded commutative ring with identity and $M$ a graded $A$-module. Let $m, n$ be positive integers with $m>n$. A proper graded submodule $L$ of $M$ is said to be graded $(m, n)$-closed if $a^{m}_g\cdot x_t\in L$ implies that $a^{n}_g\cdot x_t\in L$, where $a_g\in h(A)$ and $x_t\in h(M)$. The aim of this paper is to explore some basic properties of these class of submodules which are a generalization of graded $(m, n)$-closed ideals. Also, we investigate $GC^{m}_n-rad$ property for graded submodules.