The Relationship of Procrastination and Self-efficacy with Psychological Vulnerability in Students

AbstractThe aim of the present study was to determine of relationship of procrastination and self-efficacy with psychological vulnerability in students. The research sample consisted of 708 who were selected from among students of Islamic Azad University Ardabil Branch through the cluster random sampling method. To collect the data, Brief Psychological Symptoms Inventory, Procrastination Scale and Self-efficacy Scale were use. Data was analysed using Pearson correlation coefficient and multiple regression analyses. The results showed that procrastination and self-efficacy are related to psychological vulnerability in students. The result of multiple regressions showed that procrastination and self-efficacy explained 40 percent of variance of psychological vulnerability in students. Results are support form role of these procrastination and self-efficacy in students. The results have important implications about prevention and counselling of students in the university

An Empirical Ultra Wideband Channel Model for Indoor Laboratory Environments

Channel measurement and modeling is an important issue when designing ultra wideband (UWB) communication systems. In this paper, the results of some UWB time-domain propagation measurements performed in modern laboratory (Lab) environments are presented. The Labs are equipped with many electronic and measurement devices which make them different from other indoor locations like office and residential environments. The measurements have been performed for both line of sight (LOS) and non-LOS (NLOS) scenarios. The measurement results are used to investigate large-scale channel characteristics and temporal dispersion parameters. The clustering Saleh- Valenzuela (S-V) channel impulse response (CIR) parameters are investigated based on the measurement data. The small-scale amplitude fading statistics are also studied in the environment. Then, an empirical model is presented for UWB signal transmission in the Lab environment based on the obtained results

The Relationship of Behavioral Activation and Inhibition Systems (BAS/BIS), Difficulty of Emotional Regulation and Shyness with Social Anxiety Disorder in Normal Adolescents

ز زمینه و هدف: اختلال های اضطرابی یکی از شایع ترین اختلال های دوران نوجوانی هستند و از مهم ترین انواع این اختلال ها می توان به اختلال اضطراب اجتماعی اشاره کرد. هدف این پژوهش، پیش بینی اضطراب اجتماعی، از طریق سه عامل سیستم های فعال ساز و بازداری رفتاری ، دشواری در تنظیم هیجانی و کمرویی بود. روش بررسی: روش پژوهش حاضر غیر آزمایشی و طرح آن از نوع همبستگی می باشد. جامعه آماری شامل کلیه دانش آموزان دختر و پسر پایه اول دبیرستان های شهرکرد در سال تحصیلی 94- 1393 بود که با روش نمونه گیری خوشه ای از میان آن ها نمونه ای به حجم1000نفر (500 پسر و500 دختر) بر اساس جدول کرجسی و مورگان انتخاب شد. جمع آوری داده های پژوهش با استفاده از پرسشنامه های سیستم فعال ساز و بازداری رفتاری(BIS/BAS)، تنظیم هیجانی(ERS) ، اضطراب اجتماعی(SPIN) و کمرویی انجام گرفت. داده ها با استفاده از آمار توصیفی(میانگین و انحراف معیار) و استنباطی(ضریب همبستگی پیرسون و رگرسیون چندگانه به روش گام به گام) با نرم افزار SPSS-20 مورد تجزیه و تحلیل قرار گرفتند. یافته ها: یافته ها نشان دادند، بین اختلال اضطراب اجتماعی با سیستم بازداری رفتاری(05/0>P) ، با دشواری در تنظیم هیجانی(05/0>P) و با کمرویی(05/0>P) ارتباط مثبت معنی دار وجود دارد. ولی بین سیستم فعال ساز رفتاری با اختلال اضطراب اجتماعی ارتباط معنی داری یافت نشد(05/

Performance optimisation of a Stirling pulse tube cryocooler with an active displacer

An in-line Stirling pulse tube cryocooler with an active displacer has been built and tested. An active displacer allows the mass flow and the pressure pulse at the cold end of the pulse tube to be easily adjusted for optimum performance. The effect of varying the active displacer phase and stroke on cryocooler performance was examined experimentally. It is demonstrated that both cooling power and efficiency have optimum displacer phase and stroke values. The pulse tube cryocooler can deliver up to 4 W of cooling at 80 K with an input power of 100 W when operating at optimal displacer phase and stroke. Moreover, a numerical Sage model was used to assess how this variation in displacer phase and stroke affects the mass flow and pressure pulse at the cold end. It is shown that the variation in displacer phase affects the cryocooler performance by varying the amplitude of the mass flow at the cold end. On the other hand, changes to the displacer stroke lead to variations in both phase and amplitude of the mass flow at the cold end

Optimising the flow within a Stirling pulse tube cryocooler

One of the key requirements for successful operation of Stirling pulse tube cryocoolers is to minimise flow mixing within the pulse tube. This requires careful design of the inlet and outlet to the pulse tube. In this study, the ow within the pulse tube of an existing cryocooler is numerically analysed. Thereafter, alternative inlet/outlet designs are suggested and analysed in order to optimise the flow within the pulse tube cryocooler. The numerical simulation have been carried out using CONVERGE CFD, a finite volume Navier-Stokes solver. The standard k − ε RANS turbulence model has been used to account for the effects of turbulence within the pulse tube