Influence of Sintering Temperature on Microstructure and Mechanical Properties of Ti–Mo–B4C Composites

Abbas Sabahi Namini,Mehdi Shahedi Asl,Seyed Ali Delbari 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

Ti–10 wt% Mo–1 wt% B4Ccomposite samples were SPSed under the circumstances of 5 min dwell time, 50 MPa externalpressure and sintering temperatures of 1150 °C, 1300 °C and 1450 °C. The role of sintering temperature on the relativedensity, microstructure and mechanical characteristics of as-sintered specimens were studied. Near fully dense relative densitywas obtained for the samples sintered at 1450 °C. The best mechanical properties including UTS, elongation, bendingstrength and micro/macro hardness were achieved for the composites SPSed at the highest temperature. The XRD resultsand also microscopic photographs disclosed the formation of TiB + TiC in-situ phases. However, there was not any evidencefor chemical reaction between Mo and other phases. The role of produced in-situ phases on the grain growth also studiedusing SEM fractographs.

Effects of Phosalone Residue on Alfalfa Weevil Larval Parasitoid, Bathyplectes curculionis (Thomson)

Q. Sabahi,Kh. Talebei 한국응용곤충학회 2005 한국응용곤충학회 학술대회논문집 Vol.2005 No.05

Latent Semantic Analysis Approach for Document Summarization Based on Word Embeddings

( Kamal Al-sabahi ),( Zhang Zuping ),( Yang Kang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.1

Since the amount of information on the internet is growing rapidly, it is not easy for a user to find relevant information for his/her query. To tackle this issue, the researchers are paying much attention to Document Summarization. The key point in any successful document summarizer is a good document representation. The traditional approaches based on word overlapping mostly fail to produce that kind of representation. Word embedding has shown good performance allowing words to match on a semantic level. Naively concatenating word embeddings makes common words dominant which in turn diminish the representation quality. In this paper, we employ word embeddings to improve the weighting schemes for calculating the Latent Semantic Analysis input matrix. Two embedding-based weighting schemes are proposed and then combined to calculate the values of this matrix. They are modified versions of the augment weight and the entropy frequency that combine the strength of traditional weighting schemes and word embedding. The proposed approach is evaluated on three English datasets, DUC 2002, DUC 2004 and Multilingual 2015 Single-document Summarization. Experimental results on the three datasets show that the proposed model achieved competitive performance compared to the state-of-the-art leading to a conclusion that it provides a better document representation and a better document summary as a result.

Spinal Surgery and Subsequent ESR and WBC Changes Pattern: A Single Center Prospective Study

Akram Zare,Mohammadmahdi Sabahi,Hosein Safari,Arash Kiani,Meic H. Schmidt,Mahdi Arjipour 대한신경손상학회 2021 Korean Journal of Neurotrauma Vol.17 No.2

Objective: Postoperative inflammation and infections are common complications of spinal surgery and have similar symptoms. However, postoperative infection may lead to a poor outcome and must be differentiated from postoperative inflammation. The objective of this study is determine the changing pattern of postoperative ESR and WBC counts, and investigate the effects of different variables. Methods: A total of 61 patients who underwent spinal surgery were enrolled in this prospective study. The erythrocyte sedimentation rate (ESR) and white blood cell (WBC) counts were measured the day before surgery and on 1st, 3rd, 5th, 7th, and 14th postoperative days. Results: WBC counts increased on the 1st postoperative day in comparison with the preoperative day (p<0.001), and they gradually decreased until the preoperative value was reached on the 14th postoperative day (p=0.14). The ESR also increased postoperatively, reaching a peak on the 5th postoperative day in comparison with the preoperative day (p<0.001) and gradually decreased thereafter. However, on the 14th postoperative day, the ESR was significantly greater than the preoperative value (p<0.001). In addition, a significant positive correlation was observed between ESR and age, duration of surgery, intraoperative blood loss, and duration of anesthesia. Conclusion: WBC count continued to rise and was the highest on the 1st postoperative day, after which it gradually decreased and attained normal values on the 14th postoperative day, while the ESR increased on the 1st postoperative day, reached the highest level in patients with and without simultaneous instrumentation on 7th and 5th postoperative days, respectively, and gradually decreased.

Predictive factors of death in neonates with hypoxic-ischemic encephalopathy receiving selective head cooling

Basiri, Behnaz,Sabzehei, Mohammadkazem,Sabahi, Mohammadmahdi The Korean Pediatric Society 2021 Clinical and Experimental Pediatrics (CEP) Vol.64 No.4

Background: Severe perinatal asphyxia results in multiple organ involvement, neonate hospitalization, and eventual death. Purpose: This study aimed to investigate the predictive factors of death in newborns with hypoxic-ischemic encephalopathy (HIE) receiving selective head cooling. Methods: This cross-sectional descriptive-retrospective study was conducted from 2013 to 2018 in Fatemieh Hospital of Hamadan and included 51 newborns who were admitted to the neonatal intensive care unit with a diagnosis of HIE. Selective head cooling for patients with moderate to severe HIE began within 6 hours of birth and continued for 72 hours. The required data for the predictive factors of death were extracted from the patients' medical files, recorded on a premade form, and analyzed using SPSS ver. 16. Results: Of the 51 neonates with moderate to severe HIE who were treated with selective head cooling, 16 (31%) died. There were significant relationships between death and the need for advanced neonatal resuscitation (P=0.002), need for mechanical ventilation (P=0.016), 1-minute Apgar score (P=0.040), and severely abnormal amplitude-integrated electroencephalography (a-EEG) (P=0.047). Multiple regression of variables or data showed that the need for advanced neonatal resuscitation was an independent predictive factor of death (P=0.0075) and severely abnormal a-EEG was an independent predictive factor of asphyxia severity (P=0.0001). Conclusion: All cases of neonatal death in our study were severe HIE (stage 3). Advanced neonatal resuscitation was an independent predictor of death, while a severely abnormal a-EEG was an independent predictor of asphyxia severity in infants with HIE.

Bidirectional Quasi-Cuk DC/DC Converter with Reduced Voltage Stress on Capacitor and Capability of Changing the Output Polarity

Asl, Elias Shokati,Sabahi, Mehran The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.3

In this paper, a bidirectional topology for quasi-Cuk dc/dc converter with capability of zero-voltage and zero-current-switching (ZVZCS) is proposed. The bidirectional quasi-Cuk (BQ-Cuk) converter has different voltage and current transfer ratio, reduced voltage stress on capacitor and capability of changing the output polarity in comparison with conventional bidirectional Cuk converter. In this paper, steady-state analysis of the quasi-Cuk converter with capability of ZVZCS in turn-on is presented. Then, critical inductances for transient from this operation to two new operations are calculated. Next, besides values designing of used elements, maximum and minimum value of their current and voltage are calculated. Finally, experimental results to verify the accuracy of the proposed converter in different operating modes are presented.

Bidirectional Quasi-Cuk DC/DC Converter with Reduced Voltage Stress on Capacitor and Capability of Changing the Output Polarity

Elias Shokati Asl,Mehran Sabahi 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.3

In this paper, a bidirectional topology for quasi-Cuk dc/dc converter with capability of zero-voltage and zero-current-switching (ZVZCS) is proposed. The bidirectional quasi-Cuk (BQ-Cuk) converter has different voltage and current transfer ratio, reduced voltage stress on capacitor and capability of changing the output polarity in comparison with conventional bidirectional Cuk converter. In this paper, steady-state analysis of the quasi-Cuk converter with capability of ZVZCS in turn-on is presented. Then, critical inductances for transient from this operation to two new operations are calculated. Next, besides values designing of used elements, maximum and minimum value of their current and voltage are calculated. Finally, experimental results to verify the accuracy of the proposed converter in different operating modes are presented.

When Thoughts Are in a Race: Area 10 and Bipolar Disorders

Shokouh Arjmand,Abdolreza Sabahi,Vahid Sheibani 대한신경정신의학회 2019 PSYCHIATRY INVESTIGATION Vol.16 No.10

Racing thought, when patients incessantly shift from one word or sentence to another while pending previous ones unfinished, is a symptom of (hypo)mania in bipolar disorders received less attention hitherto. Here, based on few evidence, we aim to unfold our hypothetical viewpoint that the frontopolar cortex that is believed to play a part in multitasking and management of competing goals might be dysfunctional in bipolar patients and may contribute in induction of flight of ideas. We then address new avenues for future research and try to encourage researchers to design more comprehensive studies to either accept or decline this proposed conjecture.

Improvement of the Performance of the Cascaded Multilevel Inverters Using Power Cells with Two Series Legs

Babaei, Ebrahim,Dehqan, Ali,Sabahi, Mehran The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.2

A modular three-phase multilevel inverter especially suitable for electrical drive applications has been previously presented. This topology is based on series connection of power cells in which each cell comprised of two inverter legs in series. In this paper, in order to generate the maximum number of voltage levels with reduced number of switches, three algorithms are proposed for determination of the magnitudes of dc voltage sources. In addition, a new hybrid multilevel inverter is proposed that is composed of series connection of the previously presented multilevel inverter and some H-bridges. The proposed topology has been compared with some other presented multilevel inverters. The performance of the proposed multilevel inverter has been verified by simulation and experimental results of a single-phase 39-level multilevel inverter.

A Filtered Transformation via Dynamic Matrix to State and Parameter Estimation for a Class of Second Order Systems

Mehdi Tavan,Kamel Sabahi,Amin Hajizadeh 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.9

The problem of state and parameter estimation for a class of second-order time-varying systems is addressed in this paper. Two classes of estimators are designed for the system under different observability assumptions. The design procedure is based on a filtered transformation via dynamic matrix. The dynamic of the matrix is derived using the Immersion and Invariance technique. Adaptive parameter convergence is guaranteed under a weaker condition than traditional persistency of excitation, called non-square-integrability condition. The proposed estimator is shown to be applicable to the input voltage and current estimation from the output voltage of the AC-DC boost converter.