Energy, economic, and environmental analysis of converging air-based photovoltaic-thermal (air/PV-T) systems: A yearly benchmarking

Two converging channel configurations of photovoltaic-thermal (PV-T) systems, i.e., inlet and outlet at different sides (Case 1) and the inlet at the middle and outlets at the sides (Case 2), are investigated numerically. The results reveal that Case 1 features a nearly uniform and lower temperature distribution (up to 7 °C) for practical air flows, and the appropriate convergence ratio is 2:1 (inlet to outlet channel height) for which the PV surface temperature is lower by 8 °C than that of a similar conventional collector. Meanwhile, energy analyses based on the so called ‘rate of extra energy gain per PV surface area..

An Epidemiological Study of Psychological Disorders in Chaharmohal & Bakhtiari Province, 2001

زمینه و هدف: برنامه‏ریزی برای ارایه خدمات اساسی بهداشت روان به افراد جامعه، نیازمند آگاهی از وضعیت موجود بیماری روانی در جامعه است. این مطالعه با هدف بررسی همه‏گیری‏شناسی اختلالات روانی در افراد 18 سال به بالاتر مناطق شهری و روستایی استان چهارمحال و بختیاری انجام گرفت. روش مطالعه: نمونه های مورد مطالعه با روش نمونه‏گیری تصادفی خوشه‏ای و سیستماتیک از بین خانوارهای موجود استان چهارمحال و بختیاری انتخاب گردیدند و از طریق تکمیل پرسشنامه اختلالات عاطفی و اسکیزوفرنیا (SADS=Schedale Affective Disorders Schizophrenia) توسط کارشناسان روانشناسی در استان، جمعاً 305 نفر مورد مطالعه قرار گرفتند. تشخیص‏گذاری اختلالات بر اساس معیارهای طبقه‏بندی DSM-IV است. نتایج: نتایج این بررسی نشان داد شیوع انواع اختلالات روانی در استان 42/16 می‏باشد که این شیوع در زنان 20 و در مردان 14/13 است. اختلالات اضطرابی و عصبی‌ شناختی به ترتیب با 52/9 و 28/3، شایع‏ترین اختلالات روانی در استان بودند. شیوع اختلالات پسیکوتیک در این مطالعه 33/0، اختلالات خلقی 63/2 و اختلالات تجزیه‏ای 66/0 بود. در گروه اختلالات خلقی، افسردگی اساسی با 30/2 و در گروه اختلالات اضطرابی، اختلال فوبی با 62/2 شیوع بیشتری داشتند. شیوع اختلالات روانی در استان در افراد گروه سنی 65-56 سال با 30، افراد همسر فوت شده با 25، افراد ساکن در مناطق شهری با 53/15، افراد بی‏سواد با 66/12 و افراد بیکار با 74/21 بیش از گروه‌های دیگر بود. نتیجه‌گیری: در این مطالعه 49/10 افراد مورد مطالعه دچار حداقل یک اختلال روانی بودند. لذا نتایج این تحقیق مسئولیت سیاستگذاران و برنامه‌ریزان بهداشتی استان چهارمحال و بختیاری و کشور در رابطه با تدوین برنامه‌های عملی و اجرایی بهداشت روان را بیش از پیش روشن می‌سازد

Prevalence and correlates of psychiatric disorders in a national survey of Iranian children and adolescents

Objective: Considering the impact of rapid sociocultural, political, and economical changes on societies and families, population-based surveys of mental disorders in different communities are needed to describe the magnitude of mental health problems and their disabling effects at the individual, familial, and societal levels. Method: A population-based cross sectional survey (IRCAP project) of 30 532 children and adolescents between 6 and 18 years was conducted in all provinces of Iran using a multistage cluster sampling method. Data were collected by 250 clinical psychologists trained to use the validated Persian version of the semi-structured diagnostic interview Kiddie-Schedule for Affective Disorders and Schizophrenia-PL (K-SADS-PL). Results: In this national epidemiological survey, 6209 out of 30 532 (22.31%) were diagnosed with at least one psychiatric disorder. The anxiety disorders (14.13%) and behavioral disorders (8.3%) had the highest prevalence, while eating disorders (0.13%) and psychotic symptoms (0.26%) had the lowest. The prevalence of psychiatric disorders was significantly lower in girls (OR = 0.85; 95% CI: 0.80-0.90), in those living in the rural area (OR = 0.80; 95% CI: 0.73-0.87), in those aged 15-18 years (OR = 0.92; 95% CI: 0.86-0.99), as well as that was significantly higher in those who had a parent suffering from mental disorders (OR = 1.96; 95% CI: 1.63-2.36 for mother and OR = 1.33; 95% CI: 1.07-1.66 for father) or physical illness (OR = 1.26; 95% CI: 1.17-1.35 for mother and OR = 1.19; 95% CI: 1.10-1.28 for father). Conclusion: About one fifth of Iranian children and adolescents suffer from at least one psychiatric disorder. Therefore, we should give a greater priority to promoting mental health and public health, provide more accessible services and trainings, and reduce barriers to accessing existing services. © 2019 Tehran University of Medical Scienc

SAMPLE SIZE DETERMINATION IN NON-RADOMIZED SURVIVAL STUDIES WITH NON-CENSORED AND CENSORED DATA

Introduction: In survival analysis, determination of sufficient sample size to achieve suitable statistical power is important .In both parametric and non-parametric methods of classic statistics, randomn selection of samples is a basic condition. practically, in most clinical trials and health surveys randomn allocation is impossible. Fixed - effect multiple linear regression analysis covers this need and this feature could be extended to survival regression analysis. This paper is the result of sample size determination in non-randomnized surval analysis with censored and non -censored data.
 Methods: In non-randomnized survival studies, linear regression with fixed -effect variable could be used. In fact such a regression is conditional expectation of dependent variable, conditioned on independent variable. Likelihood fuction with exponential hazard constructed by considering binary variable for allocation of each subject to one of two comparing groups, stating the variance of coefficient of fixed - effect independent variable by determination coefficient , sample size determination formulas are obtained with both censored and non-cencored data. So estimation of sample size is not based on the relation of a single independent variable but it could be attain the required power for a test adjusted for effect of the other explanatory covariates. Since the asymptotic distribution of the likelihood estimator of parameter is normal, we obtained the variance of the regression coefficient estimator formula then by stating the variance of regression coefficient of fixed-effect variable, by determination coefficient we derived formulas for determination of sample size in both censored and non-censored data.
 Results: In no-randomnized survival analysis ,to compare hazard rates of two groups without censored data, we obtained an estimation of determination coefficient ,risk ratio and proportion of membership to each group and their variances from likelihood function, when data has censored cases an estimate of the probability of censorship should be considered, after obtaining the varince of maximum likelihood estimator and considering its asymptotic normal distribution and by using coefficient of determination, formulas have been derived. The derived sample size formulas could attain the required power for a test adjuasted for effect of other explanatory covariates.
 Discussion: application of regression model in non-randomnized survival analysis helps to derive suitable formulas to determin sample size in both randomized and non-randomnized studies in a error level, to attain necessary statistical power. In Coxs semiparametric proportional hazard model ,since the varince of the parameter can not be stated in a simple form ,a simulation model can be used. When the coefficient of determination is partialy large the power bassed on log-rank test overestimates the true value of power, but when coefficient of determination is near to difference between powers decreases zero. By increasing of regression coefficient of determination, the difference between the log-rank test and adjusted coefficient of determination of this paper increases

Presentation of a Non-invasive Method of Estimating Arterial Stiffness by Modeling Blood Flow and Arterial Wall Based on the Determination of Elastic Module of Arterial Wall

Introduction: Arterial stiffness is an important predictor of cardiovascular risk. Several indices have been  introduced to estimate the arterial stiffness based on the changes in the brachial blood pressure. Since the  substitution  of  the  blood  pressure  changes  in  the  central  arteries  such  as  carotid  with  the  blood  pressure  changes in the brachial results in error in the blood flow, it is of importance to present an elastic parameter  based on the mechanical models without any reliance on the brachial blood pressure.   Materials and Methods: Initially, a suitable dynamic model is introduced for pulsatile blood flow in the  arteries based on Navier-Stokes the equations in fluid mechanics. Then, according to the theory of elasticity,  the equations governing arterial wall are described and coupled with the equations of fluid flow. The attained  system  of  equations  is  completed  by  the  clinical  information  obtained  from  the  carotid  artery  Doppler  ultrasound images of healthy male subject. Therefore, the Doppler ultrasound images are recorded and saved  in computer after which the center-line blood velocity, the arterial wall thickness, the period of a cardiac  cycle and the arterial radius are measured by off-line processing.   Results: The results from the analytic solution of the completed equations show that the elastic modulus for  this healthy subject is 51 kpa which is in close agreement with the result obtained from other researches.   Discussion and Conclusion: By applying this method, a non-invasive method of clinically evaluating the  arterial stiffness will be possible by the Doppler ultrasound measurement of common carotid artery without  any measurement of the local blood pressure

A resilience-oriented planning of energy hub by considering demand response program and energy storage systems

Energy hub systems meet the needs of customers in different forms of energy by coordinated operation of different infrastructures, thereby improving system flexibility, reducing losses and reducing operating costs. Due to the increase in the construction of energy hub systems in distribution networks, the issue of optimal design of energy hubs has attracted much attention. Therefore, this study presents a comprehensive model for hub design, in which the technical, economic and security criteria of the hub are fully considered. In the proposed model, the design problem is solved by considering all the operating constraints and seasonal variations of different loads and solar radiation are also taken into account. Uncertainties of electrical, heating and cooling loads as well as the output power of photovoltaic (PV) panels have been considered and in order to model these uncertainties, Monte Carlo simulation approach has been utilized. Besides, in order to improve the resilience of the hub in case of emergency conditions, uncertainties related to the outage of the equipment have been considered in the design problem. The design problem is modeled as a mixed-integer linear programming (MILP) optimization problem and the simulation results indicate that considering the uncertainties of equipment outages along with the load and radiation, despite a 26.51% increase in investment cost, leads to a significant improvement in hub resilience under emergency conditions. Also, the results demonstrate that the implementation of the demand response (DR) program has reduced the demand for power during peak hours, thereby reducing the installed capacity of the combined heat and power (CHP) unit