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Analytical study of composite beams with different arrangements of channel shear connectors
Nader Fanaie,Farzaneh Ghalamzan Esfahani,Soheil Soroushnia 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.2
Channels are implemented in composite beams as shear connectors in two arrangements, face to face and back to back. No relevant explanation is found in the design codes to clarify the preference of the mentioned arrangements. Besides, the designers do not have a common opinion on this subject; i.e., some recommend the face to face and others, back to back status. In this research, channel shear connectors in composite beams are studied analytically for both arrangements using ABAQUS software. For this purpose, they have been modeled in simply supported beams in the arrangements of face to face and back to back; their effects on the crack initiation load of concrete slabs were monitored. The stiffness values of composite beams were also compared in the two arrangements using force-displacement curve; the results are relatively the same in both cases. Furthermore, the effects of compressive strength of concrete, channel size, length and spacing of channels as well as steel type of channels on the performance of composite beams have been investigated. According to the results obtained in this research, the face to face status shows better performance in comparison with that of back to back, considering the load of concrete fracturing.
Nader Ghaffari Khaligh,Mohd Rafie Johan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.09
The pollution of water due to the release of heavy metals are particularly problematic and supplies of clean water have become a major problem worldwide. The heavy metal ions can cause toxicities and serious side effects toward human health; therefore, these metal ions should be removed from water and wastewater. A variety of strategies have been developed for efficient heavy metal removal from waters. Adsorption/ion exchange strategy play a great important role in removing heavy metal ions due to their advantages. Nanomaterials are excellent adsorbents and extensive studies have been performed to remove heavy metals from wastewater by developing and using various nanomaterials. Recent developments for the heavy metals removal by various nanomaterials, mainly including carbon-based nanomaterials, iron-based nanomaterials and photocatalytic nanomaterials in batch and flow systems are described in this review.
Perceived Stress, Alexithymia, and Psychological Health as Predictors of Sedative Abuse
Nader Rajabi Gilan,Ali Zakiei,Sohyla Reshadat,Saeid Komasi,Seyed Ramin Ghasemi 대한가정의학회 2015 Korean Journal of Family Medicine Vol.36 No.5
Background: The harmful effects of sedative medications and substances in conjunction with limited research regarding predictive psychological constructs of drug abuse necessitate further investigation of associated factors. Therefore, the present study aimed to elucidate the roles of perceived stress, alexithymia, and psychological health as predictors of sedative abuse in medical students. Methods: In this cross-sectional study, 548 students at Kermanshah University of Medical Sciences, Iran, were selected using stratified random sampling. The data were obtained using the Perceived Stress Scale, an alexithymia scale (Farsi version of the Toronto Alexithymia Scale-20), and a General Health Questionnaire to assess psychological health. Data were analyzed using discriminant analyses. Results: The results demonstrated that the user and non-user of sedative substances groups had significantly different predictive variables (except for social function disorder) (P>0.05). Physical complaints, alexithymia, and perceived stress, which had standard coefficients of 0.80, 0.60, and -0.27, respectively, predicted sedative drug use. Conclusion: The results of the present study indicate that perceived stress, alexithymia, physical complaints, anxiety, and depression are associated with sedative drug abuse.
Epidemiological and Demographic Study of Patients with Mucormycosis and COVID-19
Nader Saki,Alireza Rafati Navaei,Ali Delirrooyfard,Mina Jahangiri,Roomina Bagheri 대한의진균학회 2023 대한의진균학회지 Vol.28 No.2
Background: Coronavirus disease 2019 (COVID-19) is associated with many bacterial and fungal diseases. Aspergillus and Candida have been reported as major pathogens resulting to comorbid infections in COVID-19 patients. Objective: Recent studies have shown a considerable burden of cases affected by mucormycosis after coronavirus disease 2019 (COVID-19) infection worldwide, and some underlying factors may contribute to this condition. Hence, this study aimed to investigate the epidemiology and demographic characteristics of mucormycosis patients after COVID-19 infection in the Ahvaz province of Iran. Methods: This descriptive-analytical epidemiological study was conducted on patients who developed mucormycosis following COVID-19 for a 6-month period in 2021. A checklist based on symptoms and possible risk factors was used to collect patient information. Results: The results showed that conjunctivitis, ophthalmalgia, facial swelling, feeling of pain or pressure in the face, and sinusitis were the most common clinical manifestations of patients with mucormycosis following COVID-19. Additionally, there was a significant association between corticosteroid and prophylactic antibiotic use, pain or pressure in the face, and ophthalmalgia with the outcome variables including alive or dead (p-values = 0.002, 0.011, 0.034, and 0.004, respectively). No statistically significant difference was found between the ages of the two groups (p-value = 0.495). Conclusion: The study findings revealed that the most common risk factors for mortality include diabetes, immune system defects, and use of prophylactic antibiotics or corticosteroids.
Nader A. Al Theeb,Mohammed S. Obeidat,Manar Aljarrah,Theyab A. Alhwiti 대한산업공학회 2019 Industrial Engineeering & Management Systems Vol.18 No.4
A single machine scheduling problem with sequence-dependent setup times and setup costs has a critical role in manufacturing and service sectors to minimize orders delays and costs. This study provides multiple objectives model tosolve the single machine total weighted tardiness and setup costs scheduling problem associated with sequencedependent setup times and sequence-dependent setup costs (MOSTWTSCSD). The objectives are to minimize thetotal weighted tardiness and the total setup costs for all jobs without any certain relationship between the setup timeand the setup cost, as happened in some machines. An alternative heuristic procedure based on discrete particle swarmoptimization (DPSO) is suggested to find representative Pareto front (non-dominated) solutions. Many efficient methods have been used inside the DPSO to improve its performance. Results show that the ability of the suggested solution approach to provide a representative Pareto fronts in reasonable computational efforts compared with anotherheuristic.
Nader Nezafati,Fathollah Moztarzadeh,Saeed Hesaraki 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4
Ag ions are known for their antibacterial effects. Ag containing silicate glasses have been extended to create bioactive glasses that exhibit inhibitory effects on bacterial growth using different techniques. In this work,calcium and calcium/silver silicophosphate glasses were synthesized from the sol-gel process and their physicochemical and in vitro biological properties were studied and compared. The effect of silver concentration on in vitro bioactivity and antibacterial properties of the glasses was investigated. Ag2O was substituted for CaO in the glass formula up to 2 mol% and in vitro bioactivity of the samples was evaluated by soaking them in simulated body fluid followed by structural characterization using XRD,FTIR and SEM techniques. The results showed that both glasses favored precipitation of the calcium phosphate layer when they were soaked in simulated body fluid;however, the morphology of apatite crystals changed for the 2% mol silver containing sample. Substitution of 2%mol Ag2O for CaO seemed to slightly stimulate the rate of precipitation. The in vitro biodegradation rate of the silver/calcium silicophosphate glasses was lower than that of the silver-free one (control). Also, the antibacterial properties of the samples indicated that these effects were improved by increasing silver concentration in bioactive glass composition.
NORTH KOREA NUCLEAR CRISIS; POLICIES AND STRATEGIES
Nader Asghari,Madjid Eshaghi Gordji 한국수학교육학회 2019 純粹 및 應用數學 Vol.26 No.3
The aim of this paper is to model North Korea and USA relationship since past until now. To this end, we have used game theory. The weakness of the existing models is that they have a static nature and can’t analyze the changes of processes, strategies and results. The dynamic system of strategic games of which we have used in this article is a proper method to solve this problem. We have shown that South Korea and China play an important role in resolving the crisis.
Nader Larbi,Jamel Bessrour 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.11
Taking into account the complexity and cost of a direct experimental approach, the recourse to simulation, which can also predict inaccessible information by measurement, offers an effective and fast alternative to apprehend the problem of pollutant emissions from internal combustion engines. An analytical model based on detailed chemical kinetics employed to calculate the pollutant emissions of a marine Diesel engine in general gave satisfactory results compared to experimentally measured results. Especially, the nitric oxide (NO) emission values were found to be higher than the limiting values tolerated by the International Maritime Organization (IMO). Thus, this study was undertaken to reduce to the maximum these emissions. The reduction of pollutant emissions is apprehended with exhaust gas recirculation (EGR).