Eccentricity Fault Detection in Permanent Magnet Synchronous Generators Using Stator Voltage Signature Analysis

Hossein Hooshmandi Safa,Mohammad Ebrahimi,Hossein Abootorabi Zarchi,Mohammad Abshari 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.12

In this paper, an index is proposed for the detection of static eccentricity (SE), dynamic eccentricity (DE), and mixed eccentricity (ME) in a three-phase permanent magnet synchronous generator (PMSG). The proposed index is the amplitude of the sideband components with a particular frequency pattern which is extracted from the spectrum of the stator voltage. This index can be used in no load state prior to the loading of the generator which can cause damage in eccentricity conditions. Moreover, the proposed index works properly in loaded condition. Extraction of the proper indexes highly depends on precise computation of the necessary signals. Therefore, in order to fulfil the required precision, the time-stepping finite element method (TSFEM) is used to model the PMSG under eccentricity fault and to calculate the stator voltage as an appropriate signal for processing.

The Relationship between the Metabolic Syndrome and the Risk of Obstructive Sleep Apnea Evaluated by STOP-Bang Questionnaire in Professional Drivers in Shahroud, Iran, in 2020: A Case-Control Study

Mohammad Hossein Ebrahimi,Shayesteh Jahanfar,Mina Shayestefar 대한비만학회 2021 The Korean journal of obesity Vol.30 No.1

Background: The present study was conducted to investigate the relationship between metabolic syndrome and the risk of respiratory and sleep disorders in professional drivers. Methods: This case-control study was conducted on professional drivers in Shahroud, Iran. The snoring, tiredness during daytime, observed apnea, high blood pressure, body mass index, age, neck circumference, gender (STOP-Bang) questionnaire was first used to assess obstructive sleep apnea (OSA). Then, based on the questionnaire scores, the participants were divided into two groups: those with and those without OSA. The relationship between this disorder and metabolic syndrome was then studied. Data were analyzed using descriptive and analytical tests (P<0.05). Results: Based on the STOP-Bang questionnaire, 214 drivers with a high risk of OSA and 214 drivers with low risk were recruited for the study. According to the Adult Treatment Panel III criteria, 204 drivers (47.7%) had metabolic syndrome. There was a significant relationship between driver’s license class and the risk of OSA. Metabolic syndrome components including fasting blood sugar, triglycerides, and hypertension, but not high-density lipoprotein cholesterol, were able to predict OSA in the professional drivers. Conclusion: Given the high prevalence of metabolic syndrome and OSA, especially in drivers of high risk who may spend long hours transporting good and operating passenger vehicles, screening and treating these disorders are crucial in this part of the population. The researchers recommend holding regular training sessions about these disorders for professional drivers.

Chemical incorporation of epoxy-modified graphene oxide into epoxy/novolac matrix for the improvement of thermal characteristics

Ebrahimi Hamidreza,Roghani-Mamaqani Hossein,Salami-Kalajahi Mehdi,Shahi Sina,Abdollahi Amin 한국탄소학회 2020 Carbon Letters Vol.30 No.1

Chemical incorporation of epoxy-modifed graphitic layers in epoxy/novolac phenolic resin matrices was carried out through co-curing of epoxy and novolac resins using triphenylphosphine as catalyst. First, (3-glycidyloxypropyl) trimethoxysilane (GPTMS) was grafted on graphene oxide (GO) surface to obtain epoxidized GO layers. Then epoxy resin and GPTMS-mod�ifed GO were incorporated into thermosetting reaction using novolac resin in the presence of triphenylphosphine. Covalent attachment of GPTMS-modifed GO to the resin matrices resulted in a hybrid composite with high thermal characteristics. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis (TGA), X-ray dif�fraction, and Raman spectroscopy were used for approving modifcation of GO with GPTMS. The images resulted from scanning and transmission electron microscopies exhibited GO layers with lots of creases turning to smooth layers with a few thin ripples after modifcation with GPTMS. TGA results showed that thermal characteristics of resins were improved by the addition of GPTMS-modifed GO. Char residue of the hybrid composites containing 0.5 and 1 wt% of GPTMS-modifed GO reached 28.1 and 34.3%, respectively. Also, their maximum thermal degradation temperature was also increased by the incorporation of GPTMS-modifed GO.

Relationship between erb-B2 mRNA Expression in Blood and Tissue of Invasive Ductal Carcinoma Breast Cancer Patients and Clinicopathological Characteristics of the Tumors

Moazzezy, Neda,Ebrahimi, Fatemeh,Sisakht, Mahsa Mollapour,Yahyazadeh, Hossein,Bouzari, Saeid,Oloomi, Mana Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.1

Molecular detection methods such as RT-PCR for detecting breast cancer-associated gene expression in the peripheral blood have the potential to modify breast cancer (BC) staging and therapy. In this regard, we evaluated the potential of erb-B2 molecular marker in BC detection and analyzed the expression of erb-B2 mRNA in the peripheral blood and fresh tissue samples of 50 pretreated female BC patients and 50 healthy females by reverse transcription-PCR (RT-PCR) method. We also assessed the correlation of erb-B2 mRNA marker positivity in peripheral blood and tumor tissue samples with clinical and pathological factors in BC patients in order to evaluate its prognostic value. It was shown that there is a significant difference between healthy females and BC patients with expression of the erb-B2 molecular marker (p<0.01). A significant difference between the expression of erb-B2 in the peripheral blood and tissue samples of BC patients (p<0.01) and the frequency of circulating erb-B2 mRNA expression in peripheral blood and in tissue was detected by RT-PCR. No correlation was found between erb-B2 mRNA expression in blood or tumor tissue samples and lymph node, tumor grade, tumor stage, tumor size, patient's age, ki67, estrogen receptor (ER), progesterone receptor (PGR), P53, and HER-2 status. However, in a small subset of 31 BC patients we found that expression of erb-B2 in peripheral blood or in both peripheral blood and tumor tissue was directly correlated with lympho-vascular invasion and perineural invasion as poor prognostic features. The highest rates of erb-B2 expression in peripheral blood or tumor tissue were in the ER and PR negative and HER-2 positive group. This study suggests that the application of the RT-PCR and immunohistochemical methods for erb-B2 molecular marker detection would provide a higher detection rate, especially in early stage BC.

Constitutive Analysis and Processing Map for Hot Working of a Ni-Cu Alloy

Gholam Reza Ebrahimi,Amir Momeni,Seyed Mehdi Abbasi,Hossein Monajatizadeh 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.1

The hot deformation behavior of a Ni-Cu alloy was studied using hot compression testing in the temperature range of 950 °C-1150 °C and at strain rates of 0.001 s.1-1 s.1. Flow curves at low strain rates, up to 0.01 s.1, were typical of DRX characterized by a single peak, while at higher strain rates, the typical form of a DRX flow curve was not observed. The power-law constitutive equation was used to correlate flow stress to strain rate and temperature, and the apparent activation energy of hot deformation was determined to be about 462.4 kJ/mol. The peak strain and stress were related to the Zener-Hollomon parameter and the modeling formula was proposed. The dependence of flow stress to the Z changed at ln Z=38.5,which was considered to be a critical condition for the change in the mechanism of dynamic recrystallization. The efficiency of power dissipation was determined to be between 10-35 percent at different deformation conditions. According to the dynamic material model, stable flow was predicted for the studied temperature and strain rate ranges. Highly serrated grain boundaries at low strain rates were considered to be a reason for the occurrence of continuous dynamic recrystallization. On the contrary, at high strain rates, equiaxed grain structure was attributed to the typical discontinuous dynamic recrystallization.

Schauder fixed point theorem based existence of periodic solution for the response of Duffing’s oscillator

Ahmad Feyz Dizaji,Hossein Ali Sepiani,Farzad Ebrahimi,Akbar Allahverdizadeh,Hasan Ali Sepiani 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8

An initial-boundary value problem that is Duffing’s oscillator with time varying coefficients will be studied. Using Banach’s fixed-point theorem, the existence of periodic solution of the equation will be predicted. The method applied in this paper is the Schauder second fixed point theorem, which includes the response of structures under vibratory force systems. As an example, the dynamics of nonlinear simply supported rectangular thin plate under influence of a relatively moving mass is studied. By expansion of the solution as a series of mode functions, the governing equations of motion are reduced to an ordinary differential equation for time development vibration amplitude, which is Duffing’s oscillator. Finally, a parametric study is developed, after that some numerical examples are solved, and the validity of the present analysis is clearly shown.

Gender Role in Irritable Bowel Syndrome: A Comparison of Irritable Bowel Syndrome Module (ROME 3) Between Male and Female Patients

( Sanam Javid Anbardan ),( Nasser Ebrahimi Daryani ),( Seyed Mohammad Fereshtehnejad ),( Sahar Taba Taba Vakili ),( Mohammad ),( Reza Keramati ),( Hossein Ajdarkosh ) 대한소화기기능성질환·운동학회 (구 대한소화관운동학회) 2012 Journal of Neurogastroenterology and Motility (JNM Vol.18 No.1

Background/Aims Irritable bowel syndrome (IBS) is a widespread chronic health condition which is significantly more prevalent in women. We conducted a gender difference analysis by comparing findings of men and women to determine whether any significant differences exist or not. Methods This single-center study was conducted in Tehran, Iran during 2009-2010. IBS was diagnosed on the basis of Rome III criteria. A simple "10 point" objective questionnaire was used. Results A total number of 144 IBS patients including 44 (30.6%) males and 100 (69.4%) females with the mean age of 37.50 ± 11.50 years, were assessed. The only differently observed symptom was nausea which was significantly more prevalent in females (49% vs 18.2%, P < 0.001). The commonest subtype of IBS in male patients was diarrhea predominant IBS (38.6%); while, constipation predominant IBS was the most frequent type among females (38%). Moreover, the frequency of loose, mushy or watery stools within the last 3 months was significantly higher among males (2.11 ± 1.67 vs 1.37 ± 1.50, P = 0.009). Conclusions We report that gender is important in IBS. Although qualitative comparison of different subtypes of IBS between male and female failed to meet the statistically significant level, the answers to the corresponding questions of ROME III IBS module suggest the higher prevalence of bowel movements and looser stool in males. Moreover, nausea was reported more often by females. (J Neurogastroenterol Motil 2012;18:70-77)

Study of photochemical and sonochemical processes efficiency for degradation of dyes in aqueous solution

Afshin Maleki,Amir Hossein Mahvi,Roya Ebrahimi,Yahya Zandsalimi 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6

The degradation of two commercially available dyestuffs (C.I. Reactive Black 5 and C.I. Disperse Orange 25) by ultraviolet radiation (UV), ultrasonic irradiation (US), UV/H2O2 and US/H2O2 processes was investigated in a laboratory-scale batch photoreactor equipped with a 55 W immersed-type low-pressure mercury vapor lamp and a sonoreactor with low frequency (42 kHz) plate type transducer at 170W of acoustic power. The toxicity was also evaluated in acute toxicity studies using Daphnia magna. Results showed that color removal efficiencies by US and US/H2O2processes were negligible for both dyes. Almost complete disappearance of Reactive Black 5 (97.9%) in UV/H2O2 process was possible after 5 min of irradiation. The maximum color removal efficiency of Disperse Orange 25 after 10min of irradiation, however, was only 9.2% and reached a maximum value of 41% after 120 min of irradiation. Pseudofirst order kinetics with respect to dyestuffs concentrations was found to fit all the experimental data. The results clearly showed that both dyes examined were toxic to D. magna and resulted in quite low LC50 values.

Effect of Co-Driver on Job Content and Depression of Truck Drivers

Ali Hatami,Shahram Vosoughi,Agha F. Hosseini,Hossein Ebrahimi 한국산업안전보건공단 산업안전보건연구원 2019 Safety and health at work Vol.10 No.1

Background: Since the presence of a co-driver can be considered as a companion, partner, or friend for a driver through eliminating driver’s loneliness, it plays a significant role in health and safety of drivers. The objective of this study was to investigate the effect of co-drivers on depression and occupational stress on male truck drivers. Methods: This study was an interventional case-control study. Seventy truck drivers were selected and divided into two groups: case (33 truck drivers with co-drivers) and control (37 truck drivers without codrivers). Two Goldberg depression inventories (for evaluating driver’s depression) and the Karasek job content questionnaire (for evaluating driver’s job stress) were used to collect data which were completed by interview. Results: The results showed that job content values for the case group were higher in all dimensions except job nature. The comparison of the percentages showed significant difference between two groups. Depression rate in drivers with co-driver is truly less than depression rate in drivers without co-driver. There was significant positive relationship between dimensions of job content and depression rate. Conclusion: According to the results of this study, it can be claimed that a co-driver decreases stress and loneliness of drivers, as well as increases work performance and job satisfaction, and, in turn, leads to a decrease in job-related depression.

New PLA/PEI-functionalized Fe3O4 nanocomposite: Preparation and characterization

Meisam Shabanian,Mehdi Khoobi,Farideh Hemati,Hossein Ali Khonakdar,Seyed esmaeil Sadat ebrahimi,Udo Wagenknecht,Abbas Shafiee 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.24 No.-

In this work, Fe3O4 nanoparticles were functionalized with hyperbranched polyethylenimine (PEI). The neat Fe3O4 nanoparticles (MNP) and functionalized Fe3O4 (MNP@PEI) were separately incorporated into a polylactic acid (PLA). Compared to the neat MNP, the functionalized nanoparticles (MNP@PEI) had better dispersion in the PLA matrix. The properties of the nanocomposites were strongly related to the dispersion and interaction between the nanoparticles and PLA matrix. The heat barrier effect and high nitrogen content of the MNP@PEI nanoparticles were found to be responsible for the improvement of the thermal and flame resistance properties.