mansour nejati jahromi

In general, rotating objects always produce different rotational torques according to different dimensions and rotational speeds. In some cases, it can cause a lot of damage to equipment, so it is necessary to be aware of the amount of torque that rotating objects produce at different rotational speeds, as well as in the presence or absence of air flow. in this study, numerical and experimental analysis of non-continuous flow around a cylindrical model with vertical plates under forced rotation is performed and its main purpose is to measure the torque of rotating objects in the presence of wind current also to stabilize rotation. Rotational speeds are constant. First, an aerodynamic torque measuring device was built and then a 3-fin cylindrical model was tested in a wind tunnel, and numerical simulations of 3 and 2 fin models were performed in the same laboratory conditions by Ensys Fluent software. A good agreement was observed between the experimental and numerical results and the maximum error between them was less than 10%, which is acceptable. From the simulation results, it was observed that in every 180 degrees of rotation that the maximum cross section of the models is exposed to direct wind flow, the maximum torque produced by the 2-blade cylindrical model is 30% higher than the maximum torque produced by the 3-blade model. As the wind speed increases from 20 to 60 meters per second, the torque of the 3-fin model increases from 0.4 to 1.2 Nm, which is equivalent to 200%.

Absorbents are used in RCS reduction to prevent reflection of the wave and not interfere with the test wave.By reducing the amount of reflection in a wave using materials used in adsorbents, they reduce the reflection.The things that are to be considered in relation to these reflections are the effects of these waves, which are termed ”pure environmental reflections“, the error caused by not considering the pure reflections of the environment and other problems caused by weaknesses. The main wave of the note is noteworthy. In this research, the optimum thickness of adsorbent material has been determined using genetic and Particle Swarm Optimization (PSO) algorithms with the aim of determining the minimum amount of electromagnetic wave reflection. The genetic algorithm is used to adjust the plate resistance values as well as the PSO algorithm to determine the optimal screen thickness. The results show that determination of microwave absorption coating parameters has a significant effect on the absorption rate of the wave. The applied method provides the conditions for achieving optimal coverage.

Hundreds of millions of homes worldwide already Have Fiber to The Home (FTTH)broadband connections since this technology holds many advantages over current technologies. The need for higher bandwidth by customers persiststhe network providers to upgrade their networks.TheFTTH is the use of fiber optic cords to deliver communications signals from an operator’s central network to individual houses, buildings,residences,andchanging old copper infrastructuresin order toprovide higher bandwidth to customers.Recently NG-PON capabilitieshas opened new approach in optical fiber networks creation,operators are trying to use a single infrastructure in access layer for fixed and mobile(4G/5G)services.However, the FTTH implementation is challenging for network operators in consideration of a large amount of investment,including Capital Expenditure (CAPEX) and Operational Expenditure (OPEX). The review and classification of the most relevant approachesaboutcost reduction of FTTH implementation is done in this paperbased on a novel taxonomy.

Water, the vital element for survival and its quality and resources are substantial for every country. This study was based to investigate the effect of the magnetic field and Nano filtration on some growing characteristics of tomato such as days to germination, germination percentage, germination rate, height, root length, biomass, dry matter, chlorophyll a, b, total, carotenoids, and the absorption rate of NPK, Fe by the leaves, based on a factorial experiment in a randomized complete block design with three replicates was conducted. In this respect, two levels of magnetic field, four levels of Nano filtration and three levels of water circulation were included. Overall, the results indicated that the magnetic field had a positive influence, while the impacts of Nano filter were considerably less. Likewise, it is vital to note that the effect of the magnetic field was significantly higher in interrelationship samples. As a consequence, on the basis of the results, a magnetic water treating device has been manufactured. Overall, with the aim of the device, the required amount of chemical fertilizers would plunge by which their detrimental impacts upon environment could be reduced markedly.

Synthetic aperture radar (SAR) images due to the usage of coherent imaging systems are affected by speckle. So lots of despeckling filters have been introduced up to now to suppress the speckle. Hence, objective and subjective evaluation of the denoised SAR images becomes a necessity. Thereby lots of objective evaluating estimators are introduced to evaluate the performance of despeckling filters. However, evaluating the SAR images, two main problems exist: 1) contradiction of objective and subjective evaluations and 2) absence of the ground-truth (noiseless) SAR image of the illuminated scene. So lots of efforts had been done to introduce precise referenceless estimators for SAR images which will be compatible with subjective evaluation and the results obtained by other estimators. In this paper we propose a new edge detector and also a new referenceless estimator called “Extended Ratio Edge Detector” and “ ” respectively. These algorithms are the extended version of “Ratio Edge Detector” and “ ” estimator. Experiments on images obtained from RADARSAT-1 dataset showed that the proposed edge detector and the estimator outperform their previous versions of algorithms as the proposed parameter subjectively reports up to 0.2 better results for images filtered with FANS filter in comparison with other used methods. This is also validated by and parameters, so it is reliable tool for objective evaluation of despeckled SAR images.

A management protocol level connection line with universal mobile telecommunications system (UMTS) terrestrial radio access network is required in order to enable user’s connection in UMTS networks which is performed by transferring data streams among some pre-shared channels. In this paper international mobile subscriber identity (IMSI) is obtained by an intelligence supervise interception so that if the user identity is not allowed, the connection would be terminated by supervisor. The advantage of this method in comparison with traditional approaches is in attacking connection while it is not in safe layer. In other words, rejection of connection will be performed before any network capacity loss. Our investigation proved that the proposed method results in reduction of computational complexity and energy usage of networks. Furthermore, the probability of network intrusion is also improved.

This paper introduces a new algorithm named C2-ESPRIT to estimate the direction of narrow band signals which are not coherent. The new technique estimates direction of arrival (DOA) by dividing the received signals into two sub-array and performing sub-array processing where a new diagonal matrix is obtained. As the elements of this matrix are associated with the main angles of arrival signals, it can be used to estimate the DOA of signals. The main idea in this paper is how the signal’s sub-array are obtained and a processing method is used. Unlike the two algorithms named ESPRIT and C-SPRIT, where the result of processing the signals were a diagonal matrix and diagonal conjugated matrix, in C2-ESPRIT it may appears in the form of the square conjugate diagonal matrix. The advantages of this method compared to ESPRIT and C-SPRIT, are the reduction of the variance, high resolution and requirement of fewer samples in the receiver. MATLAB is used to compare and verify new C2-ESPRIT algorithm efficiency with three known algorithms: Root-Music, ESPRIT and C-SPRIT.

The IP Multimedia Subsystem (IMS) is a platform for the exchange of multimedia communications that was proposed by 3GPP as of the year 2002. The 3GPP proposal called for the integration of mobile cellular networks and internet technology using a completely IP-based structure. The IMS uses the protocols defined by the IETF, such as SIP, RTP and others. SIP is the backbone of the IMS network, where it is used for signaling and multimedia services control. However, security vulnerabilities are inherent in such integration. When the IMS architecture is opened for easy network access and the use of SIP, it is far more vulnerable to SIP flooding attacks. This has presented a significant security problem in new networks. In the presented method for detection, network traffic is captured in two phases, being the training phase and the test phase. The distance between the probable distributions of SIP messages in these two phases is then measured using the Kullback-Leibler divergence. Then, an adaptive threshold is defined for the Kullback-Leibler divergence which, when passed, means that an attack has occurred. The adaptive threshold is accounted for by the use of a Triple Exponential Moving Average (TEMA), and the performance of the presented detection method in various situations of normal traffic and massive attacks is evaluated. The parameters α, β, ε, and γ are used for estimating the threshold and setting a safe margin for authorized traffic. In addition, the effect of changes of the estimate and setting parameters is evaluated.

Due to geometrical errors, complexity, and interference, the steering vector in large-scale antenna arrays needs to be accurately calculated. Beamforming methods based on adaptive processing can effectively overcome complexities and limitations of large-scale arrays. Here, we present the projection-based parallel linearly-constrained minimum variance (PBPLCMV) algorithm which calculates the steering vector of the desired signal through projecting the assumed steering vector onto the signal subspace. Then, the optimum weights of the adaptive beamformer are calculated using the parallel linear constrained minimum variance (PLCMV) algorithm. The simulation results show that for low input SNRs, the proposed method has better performance and output SINRs up to 18 dB more than the output SINRs of the parallel robust recursive linearly constrained minimum variance (PRRLCMV).

Secure communication and authentication between specific receiver and transmitter is attractive subject in digital communication and remote sensing. Encryption rules and authentication are important parameters in telecommand and remote sensing. This subject is a tactical problem and an important parameter in military communications. In this paper at first we introduce encryption methods and authentication rules in remote sensing based on CCSDS standards, finally we plan a new algorithm according to use of both criteria simultaneously for military systems.

In a mobile ad hoc network, there are some features such as the ability to exploit multipath effect for information exchange with high reliability and low error rate. dealing with the aggressors and discovering the path in data transmission are of importance. Approaching these goals ends in network promotion and efficiency. In this paper, the designed protocol is able to discover multipath for information exchange with high reliability. The designed network has advantages such as resistance against error occurrence, decreasing the effect of the aggressors and discovering the path in data transmission. The network security is based on the desired encoding and encryption and it provides increased speed and mobility of the network performance and efficiency and reduces the weaknesses of the security system. With increasing the speed of the nodes and density of the network, the receipt of the packets increases about four percent which causes one percent increase in packets transition. At the same time packet overhead decreases 12% on average.