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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Iranian Journal of Chemistry and Chemical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: CFD,Tunnel fire,FDS,Pool fire,Spatial resolution
- چکیده:
- چکیده انگلیسی: In this study, the amount of generated pool fire, as a result of the release of chemicals in the case of an accident in tunnels, was simulated and the results were compared to the experimental data. At first, various amounts of spatial resolution (R*) were considered to compare the existing experimental data at different heights at the upstream, downstream and above the pool fire. The comparison studies showed that both numerical predictions and experimental measurements were, in general, comparable. Furthermore, FDS code was used to simulate the tunnel fire scenario for both cases of natural and forced ventilation. The grid using in the simulations is assessed by cells with the optimal spatial resolution and the influence of the ventilating systems on pool fire dynamic and its development was investigated. As a consequence, the temperature profile, O2, CO2, and visibility were compared in the two cases. These results showed that the ventilation system plays an important role in both fire development and heat removal by providing a safely evacuate rout in the tunnel.
- انتشار مقاله: 12-03-1395
- نویسندگان: Aziz Babapoor,Vahid Bab,Mehdi Ahmadi Sabegh
- مشاهده
- جایگاه : پژوهشی
- مجله: Control and Optimization in Applied Mathematics
- نوع مقاله: Journal Article
- کلمات کلیدی: Nonlinear equations,Efficiency index,Iterative method,Convergence order
- چکیده: در این مقاله، یک روش سه گامی مرتبه پنج برای حل دستگاه معادلات غیرخطی ارائه می دهیم. که در آن هر تکرار روش مستلزم محاسبه دو تابع، دو مشتق فرشه تابع و دو ماتریس معکوس می باشد. بنابراین اندیس کارایی روش فوق برابر $5^{frac{1}{2n+4n^{2}+frac{4}{3}n^{3}}}$ می باشد که اندیس کارایی روش فوق نسبت به روش های سه گامی دیگر بهتر است. از مزیتهای روش میتوان به تعداد تکرار، سرعت و دقت بالا اشاره کرد. نتایج عددی به دست آمده نشان از برتری روش فوق نسبت به دیگر روشهای سه گامی میباشد.
- چکیده انگلیسی: In this paper, we suggest a fifth order convergence three-step method for solving system of nonlinear equations. Each iteration of the method requires two function evaluations, two first Fr'{e}chet derivative evaluations and two matrix inversions. Hence, the efficiency index is $5^{1/({2n+4n^{2}+frac{4}{3}n^{3}})}$, which is better than that of other three-step methods. The advantages of the method lie in the feature that this technique not only achieves an approximate solution with high accuracy, but also improves the calculation speed. Also, under several mild conditions the convergence analysis of the proposed method is provided. An efficient error estimation is presented for the approximate solution. Numerical examples are included to demonstrate the validity and applicability of the method and the comparisons are made with the existing results.
- انتشار مقاله: 22-08-1394
- نویسندگان: Mehdi Ahmadi,Hamid Esmaeili,R Erfanifar
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Industrial Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Markov decision process,Multiple customer classes,Sequential decisions,Stock allocation
- چکیده:
- چکیده انگلیسی: In this article, decisions about price and stock allocation for a seller with multiple customer classes are analyzed. With each customer arrival, the seller needs to decide about accepting or rejecting the customer’s demand by considering the stock on hand. In the case of acceptance, one needs to decide about the selling price. After any change in the inventory level, decision about continuing or stopping the production is needed. The seller faces a sequential and dynamic decision making problem, which is modeled by the Markov decision process and the optimal policy is determined. Finally, the impact of optimal policy on the seller’s profit is investigated by a numerical analysis.
- انتشار مقاله: 11-08-1393
- نویسندگان: Mehdi Ahmadi,Hasan Shavandi
- مشاهده
- جایگاه : پژوهشی
- مجله: Addiction and Health
- نوع مقاله: Journal Article
- کلمات کلیدی: Methadone,Opium dependence,Intensive care units
- چکیده:
- چکیده انگلیسی: Background: Few studies have been conducted regarding the comparison of the efficacy of methadone and
tincture of opium (TOP) in controlling agitation induced by withdrawal syndrome. Therefore, the current
randomized trial study is carried out with the aim to evaluate comparisons on the efficacy of methadone and
TOP in controlling agitation caused by withdrawal syndrome in opium addicted patients in the intensive care
units (ICUs).
Methods: This clinical trial study was conducted on 60 patients admitted to ICU of Shahid Bahonar Hospital,
Kerman, Iran. After classification of the patients into two groups, the first and second groups consumed
methadone syrup (5 mg/ml) and TOP (10 mg/ml), respectively. Agitation in these patients was assessed
through the Richmond Agitation-Sedation Scale (RASS). Vital signs were also assessed. Paired sample t-test
and independent t-test were used for data analysis.
Findings: In the current study, the administered dose of methadone and TOP was 36.17 ± 26.99 and
112.67 ± 102.74 mg, respectively (P < 0.010). Methadone administration led to a significant decrease of the
patients’ vital signs, including systolic blood pressure, heart rate, respiratory rate, and Glasgow Coma Scale
(GCS) (P < 0.05). Though TOP administration decreased systolic blood pressure and GCS significantly
(P < 0.05), it had no effect on patients’ diastolic blood pressure, body temperature, heart rate, and
respiratory rate (P > 0.05). In total, no significant difference was detected between two groups regarding
vital signs (P > 0.05). However, a significant difference was seen between methadone and TOP groups in
terms of RASS score (P < 0.01).
Conclusion: According to the results of the current study, lower dose of methadone, compared to TOP, could
control agitation caused by opium withdrawal symptoms.
- انتشار مقاله: 16-02-1399
- نویسندگان: Seyed Mojtaba Sohrevardi,Mostafa Pournamdari,Raazieh Salimi,Farhad Sarrafzadeh,Mehdi Ahmadinejad
- مشاهده