55 research outputs found

    Novi pristup za poboljšanje karakteristika UPQC-a tijekom nesimetričnih i distorzijskih uvjeta tereta temeljen na teoriji trenutne snage

    Get PDF
    In order to deal with power quality problems under distortional and unbalanced load conditions, this paper presents a new control method for a four-wire three-phase unified power quality conditioner (UPQC) which is based on instantaneous power p-q theory. The proposed control approach is based on instantaneous power and is optimized by using a self-tuning filter (STF), without using any low-pass filters (LPFs) or phase locked loop (PLL), and without measuring load or filter currents. In this approach, the load and source voltages are used to generate the reference voltages of a series active power filter (APF) and source currents are used to generate the reference currents of a shunt APF. Therefore, the number of times that current is measured is reduced and system performance is improved. The performance of the proposed control approach is evaluated in terms of power factor correction, source neutral current mitigation, load balancing and mitigation of the current and voltage harmonics of distortional and unbalanced loads in a three-phase four-wire system. The results obtained by MATLAB/SIMULINK software show the effectiveness of the proposed control technique in comparison to the conventional p-q method.U ovom radu prikazana je nova metoda upravljanja za trofazni četverožični UPQC (engl. unified power quality conditioner) temeljena na teoriji trenutne vrijednosti snage koja je prikladna za upravljanje tijekom distorzijskih i nesimetričnih uvjeta na teretu. Predloženo upravljanje temelji se na teoriji o trenutnoj radnoj i jalovoj snazi i optimirano je korištenjem samopodešavajućeg fitera, bez korištenja niskopropusnih filtera ili PLL-a i bez mjerenja struje tereta i filtra. Korišteni su naponi na teretu i napon izvora kako bi se generirala referentna vrijednost napona aktivnog filtra, a struje izvora koriste se za generiranje referentne vrijednosti struje aktivnog filtra. Na taj način smanjen je broj mjerenja struje i sustav ima bolje značajke. Uz predloženi sustav upravljanja testire su mogućnosti korekcije faktora snage, smanjenja neutralne struje izvora, balansiranja tereta, smanjenje harmonika u struji i naponu. Rezultati dobiveni pomoću MATLAB/SIMULINK-a pokazuju učinkovitost predloženog sustava upravljanja

    Thinning cycles as the key factor to improve stand productivity in alder plantations

    Get PDF
    Considering the high demand for wood and other forest ecosystem services, planning and managing forest plantations to mitigate and answer these increasing issues is necessary. Thinning is one of the most common managing practices for manipulating the growth of planted trees. However, studies about the impact of the thinning-cycle on stand and soil properties are rare for Alnus subcordata C.A.Mey. in Hyrcanian Forests. The aim of this study was to investigate the effect of thinning-cycles on stand and soil properties in the Alnus subcordata plantation in the Hyrcanian Forests, Northern Iran. Three neighboring alder plantations were selected with different thinning treatment cycles: the one-time thinning-cycle (T1, thinned in 2007), three-time thinning-cycle (T3, thinned in 2005, 2010, and 2015), and no thinning as the control (C). In each plantation, 15 plots (20×20 m) were systematic-randomly established (75×50 m grid). In each plot, the characteristics of trees (diameter at breast height (DBH) and total height) and total percentage of vegetation cover were recorded. Soil physiochemical properties were studied by taking samples (0-10 cm) from each plot. The highest value of DBH, total height, tree volume, and basal area and the lowest amount of the total height to DBH ratio were observed in T3. The highest levels of vegetation diversity, evenness, and richness indices were obtained in T3. Soil moisture was significantly higher in the control. The soil pH, electrical conductivity, nitrogen, and potassium were significantly higher in T3. According to the principal component analysis, there was no difference between T1 and control. For this reason, T3 was a more beneficial treatment. Our findings suggested that in alder plantations, the reduction of above and belowground competition via the three-time thinning-cycle, in addition to the financial benefits, not only improves the quality and quantity of the remaining trees but also has a significant potential to improve soil productivity

    Prevalence of epilepsy and comorbidity of psychiatric disorders in Iran

    Get PDF
    SummaryProblemTo determine the lifetime prevalence of self- and other relative informants-reported epilepsy in nationwide study among Iranian adults of aged 18 years and over and to study the association of epilepsy with lifetime history of the psychiatric disorders.MethodTwenty-five thousand one hundred and eighty individual were selected through a randomized clustered sampling method from all the Iranian households; interviewed and used epilepsy questionnaire face-to-face at home in year 2001. From 12,398,235 households residing in Iran, 7795 families selected from 1559 clusters, 997 clusters were in urban and 582 were in rural areas, each cluster with 5 households were studied. The response rate was 90%.ResultsThe prevalence of epilepsy was 1.8%. Epilepsy was more common in females, unemployed and higher educational level. It was not significantly associated with the age group, marital status and residential areas. The most common psychiatric disorders in subjects with epilepsy were major depressive disorder and obsessive compulsive disorder. The rate of lifetime suicidal attempt was 8.1%.ConclusionLifetime prevalence of epilepsy in Iran is not low. As the other communities, it is more common in females and unemployed. However, in contrast with the other studies, it was not more common among some age groups and unmarried and low educated subjects

    The effect of antidepressant treatment on the HPA axis, changes in depression score and serum levels of TNF-α in depressed infertile women

    Get PDF
    Objectives: This study aimed to explore the effect of antidepressant treatment on the HPA axis, changes in depression score, and serum levels of TNF-α in depressed infertile women. Methods: In this randomized controlled trial research, 60 infertile women who had undergone in vitro fertilization (IVF) treatment with depression scores between 16-47 were divided into two groups. The intervention group with fluoxetine capsule was under treatment for two months before the embryo transfer, while the control group was given placebo. Depression score, serum levels of tumor necrosis factor alpha (TNF-α) as well as cortisol hormone levels were measured and recorded both before and after the intervention. The data were analyzed using SPSS version 21 software. Results: We analyzed the data related to 55 subjects who had undergone embryo transfer. 7 subjects in the intervention group and 3 in the control group got pregnant. We observed a significant decrease in the depression score (p < 0/001) and serum levels of cortisol (p = 0/001) in the intervention group. There was a significant increase in the serum levels of TNF-α in the intervention group (p < 0/001). There was a significant difference between the two groups in the number of pregnancies (p = 0.04). However, there was no statistical difference between them with regard to the number of harvested oocytes (p = 0.174). Discussion: Decrease in depression score and cortisol level, and an increase in the levels of TNF-α in the intervention group caused any changes in the number of oocytes in comparison with the control group. However, the number of pregnancies was larger in the intervention group

    Short-term Effects of PM10 to Increase Rate of Hospital Admission Cardiovascular and Respiratory of Sanandaj, Iran During 2015

    Get PDF
    Sanandaj in the west of Iran is one of the main city that suffered from Arabic Dust Storm (ADS). As Sanandaj isn’t industrial city and located in the mountainous region, one of the main sources of air pollution which has adverse effects on citizens and environment is PM10 which comes from Arabic Dust Storm. In this way, the goal of this study was to the assessment of these adverse health effects. So the hourly data of concentration of PM10 (measured by Beta attenuation method) were taken from Kurdistan Environmental Protection Agency in 2015. the 24-hour average concentration of particulate matter has exceeded about 182 times (days) more than the National Standards and WHO guideline values and the average annual concentration of PM10 were about 1.5 times more than the National Standard and WHO guideline values during the period of the exam. By means of Air Q2,2,3 software the data analyzed and baseline incidence(BI), relative risk(RR) and attributable proportion(AP) were calculated. The results of this study showed that short-term health effect of PM10 could increase of total mortality except accidents and poisoning(4.13%), hospital admission cardiovascular(4.98%), cardiovascular mortality(4.45%), hospital admission respiratory(4.45%) and respiratory mortality(0.2%). This study demonstrated that a high percentage of cardiovascular and respiratory morbidity and mortality rate increased due to the raising of the concentration of PM10. To reduce the emission of PM10 from main sources and relationship between the hospital and Kurdistan Environmental Protection Agency and whether organization and people to be alert are necessary

    The Cognitive and Psychological Factors (Personality, Driving Behavior, and Mental illnesses) as Predictors in Traffic Violations

    Get PDF
    Objective: Driving is a complex behavior and is affected by several factors. This cohort study aimed at representing the main determinants such as personality features, driving behavior, and mental illnesses on driving violation based on logistic regression. Method: In this cohort study, 800 heavy truck and lorry drivers were recruited. Participants were selected from those individuals who referred to Imam Sajjad hospital in Tehran, Iran during fall 2013 to summer 2015. Manchester Driving Behavior Questionnaire (MDBQ), Big Five Personality Test (NEO Personality Inventory), and SADS (Semi-Structural Interview) were used in this study. After 2 years, we checked all traffic violations caused by human factors involving the drivers. SPSS Version 18 was used for data analysis; t test and logistic regression (OR) was also used.  Results: The findings of the present study revealed significant differences between the 2 groups of drivers (those who were and were not involved in driving offenses) with respect to controlling the effective and demographic variables. Moreover, it was found that depression and anxiety could increase the chance of accidents (2.4 and 2.7 accidents odds, respectively) (P = 0.04, P = 0.004). Furthermore, just neuroticism could increase 1.1 odds of traffic offences (P = 0.009), but other personality traits did not have an effect on the equation. Conclusion: Consistent with previous examinations, some mental disorders may affect traffic violations.  Considering the magnitude and sensitivity of driving behavior, it is essential to evaluate multiple psychological factors in drivers before and after receiving or renewing their driver’s licenses

    An epidemiological survey of psychiatric disorders in Iran

    Get PDF
    BACKGROUND: The nation-wide epidemiological survey of psychiatric disorders in term of lifetime prevalence is not adequately known in Iran. The prevalence of lifetime psychiatric disorders was estimated among the population of aged 18 and over on gender, age group, educational level, occupational status, marital status, and residential area. METHODS: The subjects were 25,180 individuals selected through a clustered random sampling method. The psychiatric disorders were diagnosed on the bases of Diagnostic and Statistical Manual of Mental Disorders-IV criteria. It is the first study in which the structured psychiatric interview administered to a representative sample of the Iranian population age 18 and over by the 250 trained clinical psychologist interviewers. The data was entered through EPI-Info software twice in an attempt to prevent any errors and SPSS-11 statistical software was also used for analyses. The odds ratios and their confidence intervals estimated by using logistic regression. RESULTS AND DISCUSSION: The prevalence of psychiatric disorders was 10.81%. It was more common among females than males (14.34% vs. 7.34%, P < 0.001). The prevalence of anxiety and mood disorders were 8.35% and 4.29% respectively. The prevalence of psychotic disorders was 0.89%; neuro-cognitive disorders, 2.78% and dissociative disorders, 0.77%. Among mood disorders, major depressive disorder (2.98%) and among anxiety disorders, phobic disorder (2.05%) had the higher prevalence. The prevalence of psychiatric disorders among divorced and separated 22.31%; residents of urban areas 11.77%; illiterates 13.80%; householders 15.48%; unemployed 12.33% that were more than other groups. CONCLUSION: The mental health pattern in Iran is similar to the western countries, but it seems that the prevalence of psychiatric disorders in Iran may be lower than these countries. It is estimated that at least about 7 millions of Iranian population suffer from one or more of the psychiatric disorders. It shows the importance of the role of the psychiatric disorders in providing preventive and management programs in Iran

    Psychometric properties of the Farsi translation of the kiddie schedule for affective disorders and schizophrenia-present and lifetime version

    Get PDF
    BACKGROUND: Semi-structural clinical interviews are very important in the area of mental health research and services. There were no studies of the reliability and validity of the Farsi (Persian) version of Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL) in Iran. This study compares the results of face-to-face, semi-structural interview and clinical interview by a child and adolescent psychiatrist. METHOD: Subjects were 109 children and adolescents recruited to the child and adolescent psychiatry outpatient clinic of Hafez Hospital. Order of interview (in-psychiatrist or the semi-structural interview) was determined using random assignment within a counterbalanced framework. After, translation and back translation of K-SADS-PL, the Farsi version of K-SADS-PL was provided and used in the study. The interviewer was unaware of the child and adolescent psychiatrist diagnosis at the time of making the interview. Consensual validity, test-retest and inter-rater reliability, sensitivity, specifity, positive and negative predictive validity for the disorders were studied. RESULTS: Consensual validity of all of the psychiatric disorders was good to excellent. It was highest for panic disorder, conduct disorder, and simple phobia. Consensual validity of anorexia nervosa was 0.49. There was sufficient validity and test-retest and inter-rater reliability and good to excellent sensitivity and specifity and positive and negative predictive validity for nearly all of the disorders. Test-retest reliabilities of attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and tic disorder were 0.81, 0.67, and 0.56; respectively. Inter-rater reliabilities of ADHD, and ODD were 0.69 and 0.69. Tic disorder, post traumatic disorder, panic disorder, and ADHD had the highest positive predictive validities. CONCLUSION: The Farsi version of K-SADS-PL is a valid and reliable interview instrument for use in assessing and diagnosising child and adolescent psychiatric disorders

    Prevalence of obsessive-compulsive disorder in Iran

    Get PDF
    BACKGROUND: Estimates of the annual prevalence for Obsessive Compulsive Disorder (OCD) were consistent across the international sites range, 1.9% – 2.5%. The nine population surveys, which used Diagnostic Interview Schedule, estimated a six-month prevalence of OCD ranging from 0.7% to 2.1%. This study performed in order to determine the prevalence of OCD in a population-based study among Iranian adults aged 18 and older and to study the association of them with factors such as sex, marital status, education, type of occupation and residential area. METHODS: A cross-sectional nationwide epidemiological study of the Iranian population aged 18 and older was designed to estimate the prevalence of psychiatric disorders and their association with the above mentioned factors. 25180 individuals were selected and interviewed through a randomized systematic and cluster sampling method from all Iranian households. Schedule for Affective Disorders and Schizophrenia (SADS) and Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) criteria were used in diagnosis of OCD. 250 clinical psychologists interviewed the selected subjects face to face at their homes. RESULTS: The prevalence of OCD in Iran is 1.8% (0.7% and 2.8% in males and females; respectively). 50.3% of the survey sample were men, 49.9% women, 29.1% single, 67.45% married, 0.4% separated or divorced, 2.5% widow/widower and 4% undetermined. All of the above-mentioned factors were examined in the univariate and multivariate logistic regression models. Although the data did not fit the models well, but in univariate models, sex, the category "single" of marital status, age, the categories "business" and "housewife" and residential areas showed significant effect adjusting for the factors, but the models didn't fit the data properly. CONCLUSION: The study suggests that the prevalence of OCD is not rare in the community of Iran and is within the range of other countries. Similar to prior studies in other communities, OCD is more common in females than males

    Prevalence and Correlates of Psychiatric Disorders in a National Survey of Iranian Children and Adolescents

    Get PDF
    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
    corecore