Inference on P(Y<X) in Bivariate Rayleigh Distribution

This paper deals with the estimation of reliability $R=P(Y<X)$ when $X$ is a random strength of a component subjected to a random stress $Y$ and $(X,Y)$ follows a bivariate Rayleigh distribution. The maximum likelihood estimator of $R$ and its asymptotic distribution are obtained. An asymptotic confidence interval of $R$ is constructed using the asymptotic distribution. Also, two confidence intervals are proposed based on Bootstrap method and a computational approach. Testing of the reliability based on asymptotic distribution of $R$ is discussed. Simulation study to investigate performance of the confidence intervals and tests has been carried out. Also, a numerical example is given to illustrate the proposed approaches.Comment: Accepted for publication. Communications in Statistics- Theory and Methods, 201

Investigating the relationship between organizational factors of stress and delay of software projects in a large knowledge based company.

According to psychologists, stress means the pressure and the force and it is the accumulation of life events that disrupts the individual's adaptation to the existing situation. Stress is originated from two places: Inside our bodies and outside our bodies. Internal stresses are associated with biology and personality. External stress factors have three categories: Personal, Organizational and environmental. On the other hand, today, software projects have delays for various reasons and they are not completed on time. Knowledge-based companies require identifying factors causing delays. The aim of this study is to investigate the relationship between organizational factors of stress and delays of software projects. This is a descriptive correlational research. The population consisted of knowledge workers of a large knowledge-based company (n = 200), a sample of 127 knowledge workers were selected randomly. The data collected through questionnaire. The effect of organizational factors of stress on delay of software projects were assessed using Pearson correlation coefficients. The results show that there is a significant positive relationship between organizational factors of stress and delay of software projects in a large knowledge-based company

Aceptación de la innovación y la satisfacción del cliente: una encuesta sobre los sistemas de Información tributaria

The pace of introducing innovation-based products and services to the market is increasingly fast and it significantly affects customer  satisfaction,  not only for consumer  products  and services, but also in the delivery of public service services.  This paper uses innovation acceptance  and technology adoption models to investigate the acceptance and satisfaction  of taxpayers  from introduction  of new tax information system  in Iran. By a review of existing models and related effective factors, a conceptual model has been developed based on DeLone-McLean model, and was applied on users in the Iranian tax information system.  Findings of this research  show that factors that lead to information transparency  and more participatory users have a positive effect on innovation acceptance and the satisfaction  of users of such technologies.El ritmo de introducción al mercado de productos  y servicios  de base innovadora es cada vez más rápido y afecta significativamente la satisfacción del cliente, no sólo por los productos  y servicios de consumo, sino también en la prestación de los servicios públicos. Este artículo utiliza los modelos  de aceptación de la innovación  y de adopción de tecnología para investigar la aceptación y satisfacción de los contribuyentes en cuanto a la introducción de nuevos sistemas de información tributaria en Irán. A través  de una revisión de los modelos existentes  y los factores efectivos relacionados, ha sido desarrollado un modelo conceptual basado en el modelo DeLone-McLean y fue aplicado en usuarios en el sistema de información tributario iraní. Los hallazgos de esta investigación muestran que los factores que contribuyen a la transparencia en la información  y a generar usuarios más participativos tienen un efecto positivo en la aceptación de la innovación y la satisfacción  de los usuarios de dichas tecnologías

Economía política de los medios de comunicación: análisis de ingresos y gastos de las ayudas estatales a los periódicos iraníes

Iranian newspapers have traditionally relied on state aids and public budget to survive. The dependency has still lingered amid a change of policy that has affected the newspapers’ financial status. This article invokes the available data on governmental support to examine the political economy of newspapers in Iran during the two decades of 1990s and 2000s. The data were collected from official releases by the Iranian Ministry of Culture and Islamic Guidance as well as several nonconfidential internal bulletins of the newspaper organizations. Having applied an income-expense analysis, the paper explains the government’s role in newspaper economics and discusses the policy of repurposing the existing subsidies.Los periódicos iraníes han dependido tradicionalmente de las ayudas estatales y del presupuesto público para sobrevivir. La dependencia aún persiste en medio de un cambio de política que ha afectado la situación financiera de los periódicos. Este artículo invoca los datos disponibles sobre el apoyo gubernamental para examinar la economía política de los periódicos en Irán durante las dos décadas de 1990 y 2000. Los datos se obtuvieron de comunicados oficiales del Ministerio de Cultura y Orientación Islámica de Irán, así como de varios boletines internos no confidenciales de las organizaciones de periódicos. Habiendo aplicado un análisis de ingresos y gastos, el documento explica el papel del gobierno en la economía de los periódicos y discute la política de reutilización de los subsidios existentes

Sound level in a ten year period in Shahrekord City

چکیده: زمینه و هدف: صوت یا صدا، بخشی از زندگی روزمره بوده و برای انجام وظائف طبیعی بدن انسان ضروریست. صدا نیز همانند کلیه آلاینده ها، کیفیت زندگی را کاهش داده و باعث مخاطرات بهداشتی قابل توجهی می شود. این مطالعه با هدف بدست آوردن اطلاعات زمینه در رابطه با وضعیت سرو صدا در محیط شهری و تعیین تغییرات در تراز بندی صدا نسبت به زمان و تعیین اثر اصلاح الگوی شهرسازی در میزان آلودگی صوتی به‌ منظور بکارگیری اقدامات عملی برای محدودسازی و کنترل میزان مواجهه با صدای محیط انجام شد. روش بررسی: این تحقیق که از نوع قبل و بعد می باشد در دو مقطع زمانی (اول در سال 1372 و دوم 1381) انجام گرفت. به منظور تراز بندی صدا در سطح شهر، بر اساس مناطق متنوع و پر ترافیک، متوسط و آرام، مسکونی، آموزشی و درمانی در مقطع اول 8 ایستگاه اندازه گیری و مقطع دوم 10 ایستگاه اندازه گیری در نقاط مختلف تعیین گردید. بمنظور تعیین ردیف صدا در میان مشکلات زیست محیطی بر اساس عقیده عمومی، بصورت تصادفی 20 نفر در هر ایستگاه (شامل عابرین و ساکنین در محل) انتخاب و از آنها نظر خواهی شد و داده ها با استفاده از آزمون های آماری ویلکاکسون، کای دو و دو جمله ای تجزیه و تحلیل گردید. یافته ها: متوسط سطح صدا در روز برای مقطع اول و دوم به ترتیب 3/6±8/68 و 7/7±8/73 دسی بل (05/0

The effect of submerged filter and ozone on biological treatment of wastewater

Background and aim: Wastewater treatment is carried out with various techniques. The conventional techniques are used for treatment of wastewater containing biologically active materials. The limitations of active-sludge method are production of sludge and failure of removal of carbohydrate and organic containing pollutants. Combination techniques are used successfully for treatment of industrial effluents including petrochemical, textural and similar wastewater. The aim of this study was to perform a combined biological system including fixed media reactor (Biofilm system) and ozonation and to compare the results with those of the conventional techniques. Methods: This experimental-applicable study was performed to construct an experimental model using an aerated fixed film biological reactor with ozonation. At first, the imported and exported parameters of treatment plant of Shahrekord were tested. Then, following the set up of a pilot plant, the effluents of the plant using biological treatment with and without ozonation were measured. Results: Our results showed that the mean of chemical oxygen demand (COD) in the pilot input was 541.2±171.3 mg/lit and in its output at the first and the second step was 226.6±194.4 and 64.1±26.6 mg/lit, respectively (p0.05). The percentage of decolonization was 80 to 90 percent. The efficiency of ozone transfer to wastewater was 35 to 45 % and ozone consumption for each gram of COD removal was 0.35 to 0.75 milligram. Conclusion: The results indicated that the combination of ozonation and fixed media biological reactors are strong tools for treatment of pollutants in wastewater. Removal of organic pollutants was considerably higher than that of the conventional methods and the sludge production was the lowest

In Vitro Comparison Of Fluoride Gel Alone and in Combination With Er,Cr:YSGG Laser on Reducing White Spot Lesions in Primary Teeth

Introduction: Laser therapy has been suggested as a method for caries-prevention, and ErCr:YSGG laser is increasingly used in dentistry. This study aimed to compare the efficacy of fluoride gel alone and in conjunction with Er,Cr:YSGG laser for remineralization of white spot lesions (WSLs) in primary teeth.Methods: This study was conducted on 20 primary teeth with WSLs extracted for orthodontic reasons. Three sections were made of each tooth at the site of WSLs. The surface area of WSLs was measured under a stereomicroscope at ×25 magnification. Samples were assigned to 3 groups of control (group 1), exposure to 1.23% APF gel for 4 minutes (group 2) and Er,Cr:YSGG laser (0.5 W power, 20 Hz frequency, 60% water, 40% air, pulse duration of 5±1 seconds) plus fluoride (group 3). All samples were stored in artificial saliva for 10 days and then the surface area of the WSLs was measured again under a stereomicroscope. Data were analyzed using the Kruskal-Wallis, Mann-Whitney and Wilcoxon signed rank tests.Results: The reduction in surface area of the WSLs was significantly different between the control and fluoride (P &lt; 0.001) and also the control and laser plus fluoride groups (P &lt; 0.001); the difference between fluoride and laser plus fluoride groups was not significant (P = 0.265). Comparison of the surface area of WSLs before and after the intervention showed no significant difference in group one (P = 0.737) while this difference in groups 2 (P &lt; 0.001) and 3 (P &lt; 0.001) was statistically significant.Conclusion: The results showed that Er,Cr:YSGG laser irradiation plus 1.23% APF gel was not significantly different from the application of fluoride gel alone in enhancing the remineralization of WSLs