Quarantine region scheme to mitigate spam attacks in wireless sensor networks

The Quarantine Region Scheme (QRS) is introduced to defend against spam attacks in wireless sensor networks where malicious antinodes frequently generate dummy spam messages to be relayed toward the sink. The aim of the attacker is the exhaustion of the sensor node batteries and the extra delay caused by processing the spam messages. Network-wide message authentication may solve this problem with a cost of cryptographic operations to be performed over all messages. QRS is designed to reduce this cost by applying authentication only whenever and wherever necessary. In QRS, the nodes that detect a nearby spam attack assume themselves to be in a quarantine region. This detection is performed by intermittent authentication checks. Once quarantined, a node continuously applies authentication measures until the spam attack ceases. In the QRS scheme, there is a tradeoff between the resilience against spam attacks and the number of authentications. Our experiments show that, in the worst-case scenario that we considered, a not quarantined node catches 80 percent of the spam messages by authenticating only 50 percent of all messages that it processe

A case of risk assessment by using Fine-Kinney method in sub-leather processing

One of the most hazardous industries in the district of Bolu-Gerede of Turkey, leather-processing industry, takes an important place for the economy of the district and the country. The study was carried out in a medium-sized company operating in the leather processing sector in Bolu. Preventing the occurrence of industrial accidents and occupational diseases is one of points to be emphasized in terms of companies and laborers in the industry. Occupational health and safety are concepts that increasingly become more important in today’s societies. Awareness is raised and legal issues come to the fore regarding these concepts comprising a dimension of human health. Scientists are studying on occupational health and safety and looking for ways to prevent the accidents before they occur. In the study, Fine-Kinney risk analysis method has been applied in the sub-processes of a sample manufacturing company in the district; and the activities whose risk scores are very high after the study and high-risk activities have been handled in the first place; and it is observed that the risk-scores decreased after the regulatory and preventive practices. As for other activities, whose risk scores are lower, action plans were implemented. With this study, it is stated that the risk assessment is a proactive approach in occupational health and safety practices and the company's risk scores have been significantly reduced

Correlation between physical measurements and observer evaluations of image quality in digital chest radiography

Purpose: The aim of this paper was to investigate the relationship between the physical and subjective (observer) image quality metrics in digital chest radiography. Methods: Five digital radiography systems, four with indirect flat panel detector and one with storage phosphor-based computed radiography system, were used in the study. The physical image quality assessments were carried out using effective detective quantum efficiency (eDQE) metric and subjective performance of the digital radiography systems was evaluated in terms of inverse image quality figure (IQFinv) derived from the contrast-detail (CD) diagrams using CDRAD 2.0 phantom and CDRAD phantom analyzer software. All measurements were performed for different tube voltages (70, 81, 90, 102, 110, and 125 kVp) and polymethyl methacrylate (PMMA) phantom thicknesses. An anthropomorphic chest phantom and visual grading analysis (VGA) technique based on European image quality criteria for chest radiography were used for clinical image quality evaluation. Results: The Spearman correlation coefficients were calculated for the investigation of the correlation between physical image quality and clinical image quality. The results showed strong positive correlation between the physical and clinical image quality findings. The minimum correlation coefficient was 0.91 (p < 0.011) for IQFinv vs VGA scores and 0.92 (p < 0.009) for IeDQE vs VGA scores. Conclusions: Our results confirm that clinical image quality can be predicted with both physical assessments and contrast-detail detectability studies

Sensor wars: detecting and defending against spam attacks in tactical AdHoc sensor networks

Anti-nodes deployed inside a wireless sensor network can frequently generate dummy data packets that make the nodes relaying them deplete their energy. Especially the nodes closer to the sink fail sooner, because they convey more data packets. This causes the sink to be disconnected from the sensor network. The counter-measures for this type of attacks, namely spam attacks, should consider that the sensor nodes have limited energy, computational power and memory. In this paper, we propose detect and defend against spams (DADS) scheme. In DADS the vicinity of the detected malicious node is notified about the quarantine region, and nodes do not relay unauthenticated messages coming from a node in the quarantine region. Our experiments show that our scheme fits the requirements of the sensor network

Evaluation of Satisfaction of Students at Giresun University

Bu çalışmada Giresun Üniversitesinde 2016-2017 eğitim--öğretim yılında öğrenim gören öğrencilerin kendi üniversitelerine yönelik hizmet kalitesi algılarının ve memnuniyet düzeylerinin ölçülüp bunların karşılaştırılması amaçlanmıştır. Araştırma verileri 2016-2017 eğitim--öğretim yılında Giresun Üniversitesine bağlı Fakülte, Yüksekokul ve Meslek Yüksekokullarında öğrenim gören toplam 437 öğrenciden toplanmıştır. Araştırmada veri toplama aracı olarak Dilşeker (2011) tarafından geliştirilmiş olan memnuniyet anketi kullanılmıştır. Anket üç bölümden oluşmaktadır. İlk bölümde öğrencilerin hizmet kalitesine ilişkin algılarını ölçmeye yönelik olarak fiziksel özellikler, destek hizmetleri, uluslararasılaşma, akademik personel ve akademik olmayan personel değişkenleri kapsamında 52 ifadeye, ikinci bölümde öğrenci memnuniyeti, imaj, tavsiye ve sadakat ile ilgili 13 ifadeye yer verilmiştir. Araştırmada elde edilen sonuçlara göre Giresun Üniversitesinde öğrencilerin hizmet kalitesi ve öğrenci memnuniyet algısının en yüksek Meslek Yüksekokulu öğrencileri arasında olduğu görülmektedir.his study aims to find out and compare the service quality perception and the satisfaction level of students attending Giresun University towards their own university in the 2016-17 academic year. The data was collected from 437 students attending to the faculties, schools, and vocational schools of Giresun University. survey, developed by Dilşeker (2011), was used as data collection tool. The survey has three sub-categories. The first part includes 52 statements asking for students’ ideas on service quality like physical conditions, support services, internationalization, academic and non-academic staff. The second part presents 13 statements regarding students satisfaction, image, recommendation and loyalty. The results of the study reveal that vocational school students have the highest level of satisfaction and service quality perception