جستجوی مقالات مرتبط با کلیدواژه « mobility » در نشریات گروه « فنی و مهندسی »

Vehicular ad-hoc networks are a sub-category of mobile ad-hoc networks. The most important routing challenges in these networks include: reducing network overhead, avoiding congestion, and increasing packet delivery rates. In vehicular networks, on-time broadcasting and sending warning messages, such as accident and damage prevention, congestion control, and road condition messages to vehicles exposed to danger is of particular importance. In this paper, a new approach called VMDR-VANET is proposed to improve routing in vehicular ad-hoc networks. This approach selects the appropriate vehicle to send a packet to the target using an alert message to the neighboring vehicles and considering the distance, speed, delay, and density criteria. In addition, it can be used both for direct routes and for predicting the movement of vehicles at intersections. The results of the VMDR-VANET simulation show the proper performance of this approach so that on average, it has improved by 62 percent in packet delivery rate, 45 percent in end-to-end delay, 25 percent in hop count, and 30 percent in routing overhead compared to similar works.

Quick development of technologies and emergence of Internet of Things technology that can link everything environment us is one of the most amazing developments environ the universe. Need to connect and manage fixed and mobile nodes in this type of networks in order to create a proper interaction among them, addition to solving many serious limitations, has caused researchers to address various challenges of this technology. One of the most important challenges is to provide an efficient routing protocol that is able to manage different aspects of network efficiency alongside manages mobility of nodes and dynamic topology of network. RPL (Routing Protocol for Low Power & Lossy Networks) is one of the famous routing protocols is proposed for internet of things networks. This protocol is designed specifically for Internet of Things networks with fixed nodes, so we developed a new routing algorithm called A-RPL to support mobility and solved some challenges caused by mobility. Our algorithm works better than some superior algorithms were proposed in recent years, because they still suffer from various disadvantages, especially for mobile networks

In this work, three imidazole compounds were synthesized as fluorescent materials for organic light-emitting diodes (OLEDs). In the step, single and multi-layers OLEDs using imidazole compounds have been fabricated.  The highest luminous efficiency was observed with the compound (1). Diode fabricated with thiophene increased efficiency with respect to other compounds. Also, in the electroluminescence spectrum of the phenyl ring, electroplex emission was achieved. The results show that the color of devices depends on functional groups. The effect of various thicknesses (90,100 and 150 nm) on the electron mobility of devices with space-charge-limited current (SCLC) method was investigated. The highest mobility at the optimum thickness of 90 nm was achieved.

In line with the efficiency is the principle of all organizations and planning managers, everyone is trying to identify the recovery factors and increased productivity,, according to the concerns of managers and support centers regarding to improve performance seems that education is part of the concerned and eliminates concerns that in this case the need for education in the logistics and the importance of its holding will be serious, and also The stability and continuity of training is necessary to study the factors affecting it. So The aim of study is to evaluate training Logistics ( logistics ) in the transport sector and mobility ( transportation of personnel and equipment) in the training center of shahid dastvareh on performance of the support centers.
The research is a sort of functional goal and its methodology will be survey descriptive and quantitative data collection tools have been used of questionnaire.
The statistical population is 140, the number of 22 questions based on operational definitions of the variables in the form of a questionnaire using a range Likert response to the 20 questions has been prepared for the job behavior and for learning from pre-test and post-test and the results were used to estimate because of the lack of necessary information.
The analysis of this study is conducted based on Kirkpatrick's four-level evaluation. In this method the efficacy of education in the field of mobility and transport logistics model has been assessed with four levels (reaction, learning, behavior and results).
As a result the findings of the assessment of learning outcomes at the level of 76.53% reaction, learning78.77% and behavior 72.72% is obtained, which was perfected with job evaluation selective model (Kirkpatrick) and the positive average of courses in Logistics at the top 76% is finally presented proposals to address the shortcomings of the users.

In this paper, a framework for optimizing operation of light tactical vehicles in corps of Defense Force offered. There are many models for optimizing operation and check the number of existing models, the proposed model was presented. The main processes include the "relevant selection criteria and priorities" is. In terms of data collection, interviews and questionnaires have been distributed.The population of experts and managers working in the field of transportation, logistics and support that is familiar to them. Criteria for approval, a questionnaire were distributed among 50 experts and 44 completed questionnaires were collected to determine the validity by using lavshh formula and were approved with modifications. The reliability of the statistical analysis software SPSS was assessed using Cronbach's alpha value was greater than 0.7, indicating that it is reliable.The main measures optimizing utilization of light tactical vehicles in this study consisted of "supply and procurement, distribution, storage, maintenance and operation" is detected And analyzed using the Friedman (nonparametric) and TOPSIS conceptual model of the causes and the reasons for their subsidiary's ratings. The output of this project was to implement the appropriate Corps.

GaAs is a binary III-V compound semiconductor in the periodic table. Having a direct energy gap of 1.42 eV at room temperature, GaAs is one of the widely used semiconductors in the technology and creation of solid state electronic devices such as solar cells. From this view point, study of the electronic properties of GaAs single crystals is of prime importance. In this experimental work, transport properties of two kinds of p-type GaAs samples each doped with Cr and Co have been studied in the wide temperature range (100-400) K. Apart from temperature dependency of mobility of charge carriers also different predominant scattering mechanisms occurring in these crystals have been given. Analysis of the temperature dependency of mobility, shows that, two kinds of scattering mechanisms namely, ionic and lattice scatterings are the dominant mechanisms at low and high temperatures, respectively.

Connected Vehicle Technology (CVT) is a great step in evolution of Intelligent Transportation Systems (ITS). In this technology، some equipments installed in vehicles and road sides exchange critical vehicle data such as position، speed، and direction of movement in a given range with each other، so that the drivers will gain a situational awareness in their vicinity and will be able to make appropriate real-time decisions in an effective manner. In addition to safety and vital applications، this technology can help mobility and reduce traffic congestion. Furthermore، having access to adequate information، the drivers can choose better routes، improve their driving behaviors، and make their trip more fuel-efficient and eco-friendly. This study introduces connected vehicle technology concepts and surveys the relevant applications including safety، mobility، environmental issues etc.

Intelligent Transportation Systems (ITS) offer various innovations that can transform transportation systems. According to many experts، the greatest driving force of the ITS evolution will come from the Connected Vehicle Technology (CVT). The effective wireless communications deployed in this technology، has the capability of transforming transportation safety، mobility and also reducing environmental impacts using Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communications. Implementing the connected vehicle technology not only provides a futuristic vision for this technology but also transforms the intelligent transportation systems worldwide. The governmental organizations، transportation research centers and car manufacturers are trying to develop this technology and they''ve already achieved some notable achievements. This study investigates the impacts and role of the vehicular communications in intelligent transportation systems.