Robust Resource Allocation for OFDM-based Cognitive Radio in the Presence of Primary User Emulation Attack

Cognitive radio (CR) is a promising solution to improve the spectrum efficiency in which some unlicensed users are allowed to exploit frequency bands which are not used by licensed network. However, CR technology imposes some threats to the network. One of these threats is primary user emulation attack where some malicious users try to send fake signals similar to the primary user (PU) and prevent secondary users from accessing vacant bands. Moreover, the presence of a primary user emulation attacker (PUEA) leads to additional interference to the CR and consequently, the efficiency of conventional power loading algorithms will be degraded. In this paper, we propose a power allocation scheme in an orthogonal frequency-division multiplexing (OFDM) based CR in the presence of PUEA. Power allocation is performed with the aim of maximizing the downlink transmission capacity achieved by the cognitive user, while keeping the interference level at the PU below a predefined threshold. Simulation results confirm the efficiency of our proposed power loading scheme, compared to classical loading algorithms that do not consider the activity of malicious users in the radio environment

Studying the Relationship between Educational Managers’ Thinking Style and Transformational Leadership Style Sari Islamic Azad University as Case Study

The purpose of this study is to investigate the relationship between educational managers’ thinking style and transformational leadership style in Sari branch of Islamic Azad University. The present study is a descriptive-correlational research. The statistical population of this study includes all educational managers (both assistantsand heads of departments) in Sari branch of Islamic Azad University. The statistical population consists of 59 members (including 3 faculty chairs, 9 assistants, and 49 educational managers). In order to collect the research data, questionnaire of thinking styles and questionnaire of transformation leadership were used. Both descriptive and inferential statistics were used for analyzing the research data and testing the hypotheses. T-test is the main statistical method which was used for this purpose. The findings revealed that educational managers’ thinking style is judicial style from functional view, is holistic one from level perspective, is an outward-oriented one from scope view, and is a liberal one from tendency view. The findings also revealed that measure of transformational leadership style of the educational managers is an ideal-influence model. Based on the findings of this study, it can be concluded that educational managers of this university have a hierarchy-based thinking style and oligarchy style and mental motivation measure in their style. Keywords: style, thinking, manager, training, leadershi

Evaluation of the optical flow methods on facial expression classification

Facial expression recognition is an important issue in modern human computer interaction (HCI). In this work, the performance of optical flow in tracking facial characteristic points (FCPs) is examined and it is used as an application for facial expression classification. FCPs are extracted using active appearance model (AAM), and the features selected to the classification are the perceived movements of the FCPs and the changes in the geometric distance between them. This work compares four different optical flow methods on FCP tracking: normalized cross-correlation, Lucas-Kanade, Brox, and Liu-Freeman. Nearest neighborhood rule is used for the classification. Evaluations are done on the Cohn-Kanade (CK+) database for five prototypic expressions. Experimental results show that Lucas- Kanade method outperforms the other three optical flow methods. This has been assessed based on ground truth established in CK+ database

Image quality metric based on mutual information of image features

Objective image quality assessment has always been a challenging issue among image processing scientists. Here, a novel image quality metric based on mutual information of image features is presented. The proposed metric calculates the amount of information that one image contains about the other. Normalized feature vectors extracted from the test and reference images represent the considered information as the marginal probability distributions. In order to use the mutual information we need not only the marginal probability distributions but also the joint distribution between two images. In this work, Nelsen's method is employed to estimate the joint probability distribution from marginal distributions using the correlation between two feature vectors. Experimental results and comparisons with other well-known full-reference metrics like SSIM, MSSIM, FSIM and SFF certify the soundness of our proposed metric

Integration of Distributed Energy Storage into Net-Zero Energy District Systems: Optimum Design and Operation

A net-zero energy district is any neighborhood where the consumption of the buildings is offset by on-building generation on an annual basis. In this study, a net-zero energy district is identified among the set of optimal solutions and the effects of storage on its performance is investigated. It is assumed the model simultaneously optimizes the location of host buildings (energy generators), type of technologies and associated size, and the energy distribution network layout together with the optimal operating strategy. The optimization model addresses all technologies with a special focus on the effect of application of energy storage. Two types of energy storage are considered inside each building: thermal energy storage (hot water tank) and electrical energy storage (battery bank). The model is applied to the new part of a district energy system located in Switzerland. The best integrated district energy systems are presented as a set of Pareto optimal solutions by minimizing both the total annualized cost and equivalent CO2 emission while ensuring the reliable system operation to cover the demand. The results indicated that selection of the proposed optimal district energy system along with the storage brings great economic and environmental benefits in comparison to all other scenarios (conventional energy system, stand-alone system, and net zero-energy without storage)

The Comparative Study of the Effectiveness of Cimetidine, Ranitidine, Famotidine, and Omeprazole in Treatment of Children with Dyspepsia

Background. Functional dyspepsia is a common chronic disorder with non specific upper abdominal pain or discomfort. Different approaches with anti-secretory, spasmolytic, prokinetic and anti-inflammatory effects and most preferably reduction of visceral hypersensitivity seem logical. In this study, we compared the effectiveness of the four most drugs used for treatment of dyspepsia in children. Methods. 169 patients between 2 to 16 years old that 47.3% was male and 52.7% was female were enrolled in this clinical trial study by the diagnosis of functional dyspepsia. Then for each patient one of the drugs; Omeprazole, Famotidine, Ranitidine or Cimetidine was administered, for a period of 4 weeks. Patients were followed after 2 and 6 weeks from the beginning of the treatment. Results. The distribution of drugs between these patients were including; 21.9% with Cimetidine, 21.3% with Famotidine, 30.8% with Omeperazole and 26% with Ranitidine that the proportion of patients with all symptoms relief were: 21.6% for Cimetidine, 44.4% for Famotidine, 53.8% for Omeprazole and 43.2% for Cimetidine (P = .024). In followups within 2 and 6 weeks after beginning medical therapy, no side effects due to drugs were seen. Conclusion. If a cure is defined as all symptoms relief after a period of 4 weeks treatment, our findings showed that Omeperazole are superior to Ranitidine, Famotidine, and Cimetidine for management of functional dyspepsia

The clinical presentation of Post-Transplant Lymphoproliferative Disorder (PTLD) following pediatric liver transplantation

Post-transplant lymphoproliferative disorder is a life-threatening complication of solid organ transplantation. In pediatric recipients, PTLD has been reported in 6.4-19.5 of lung, heart and heart-lung transplants, 4-15 of liver transplants and 1.2-10.1 of kidney transplants. Although most lymphomas typically occur in lymph nodes, extranodal involvement is also common. The aim of our study was to determine the site and symptoms of PTLD in children who underwent liver transplantation during 2009-2012 in Liver Transplantation Center of Nemazee Hospital. Material and methods: This study is a cohort study on existing data of children who received liver transplant between Juanury 2009 and December 2012 at Liver Transplant Center of Nemazee Hospital in Shiraz. During the study period, the PTLD occurrence was assessed in follow up visits, if the diagnosis of PTLD was confirmed the affected patient was entered the study and additional information was obtained. The diagnosis of PTLD was considered in patients with fever of undetermined origin, lymphadenopathy, allograft dysfunction, and pulmonary infiltrates. The data was analyzed using SPSS software ver.18. Statistical descriptive methods, Chi square test, and independent t-test, were used for analyzing the data. P value smaller than 0.05 were considered significant. Results: Totally, 203 children undergoing liver transplant surgery were evaluated. The age range of patients was 8 months to 18 years with mean of 8.8±5.6 years old. In our study 17 (8.4) patients developed PTLD. The mean interval between transplantation and PTLD diagnosis was 8.4 ±5.61 months ranging from 4 to 24 months. A total of five patients (2.5) died during the follow-up period and all of them were PTLD affected children (29.4 of PTLD patients). Lymph nodes were the most predominant site involved (64.7), while liver and GI involved in 35.2. Conclusion: The results of this study emphasize the relatively high incidence of PTLD after liver transplantation in children. Because of its impact on patient's outcome and reducing recipient's survival, it is important to minimize this problem by early diagnosis and providing effective treatment

Evaluation of hydrophilic properties of acrylonitrile/acrylic acid copolymer films dendrigrafted with citric acid

The present study investigates the hydrophilic properties of acrylonitrile/acrylic acid P(AN/AA) copolymer films with various acrylic acid (AA) contents dendrigrafted with citric acid from zero to fourth generation numbers. It was found that the hydrophilicity of the dendrigrafted films was a complicated phenomenon. Various parameters such as intermolecular hydrogen bonding, roughness and active functional groups affected the wettability of the film samples measured via static contact angle. The results revealed that the hydrophilicity decreased with increasing the generation number owing to the steric hindrance of terminal groups. However, active functional group increased by rising generation numbers which was confirmed using zeta potential measurement. Furthermore, the percentage conversion of the reactions showed a reduction with increasing generation number and AA content which was in agreement with the reduction in wettability corresponding to the higher contact angle. On the other hand, zeta potential as well as roughness of the films increased with successive generations

Empowering Small and Medium-Sized Knowledge-Based Companies Using Digital Entrepreneurship Development

In recent years, information and communication technology has come to the aid of entrepreneurship and a new debate called digital entrepreneurship has emerged. The purpose of this study is to present a conceptual model of digital entrepreneurship development in small and medium knowledge based companies.  After reviewing literature and interviewing with 17 experts in universities and organizations digital entrepreneurship developmental factors were presented that were 147 codes. Using content analysis and focus group methods, these codes were grouped into 29 based content and 7 organizer contents. In the next step, using interpretative structural modeling method, the modeling of the basic themes and the organizing content created and the final model of digital entrepreneurship development in SME knowledge-based companies has been made in three level of contextual, structural and content factors. The results showed that the contextual factors with the most impact and structural factors with the most impressionability, have an important role in the development of digital entrepreneurship in SME knowledge-based companies