Address Resolution Protocol (ARP) is an essential protocol for the operation of local area networks. It is used for mapping the logical address to the physical address. However, ARP was designed without any security features. Therefore, ARP is vulnerable to many ARP spoofing attacks, such as the host impersonation, man‐in‐the‐middle (MITM), and denial of service (DoS) attacks. Many techniques were introduced in the literature for mitigating ARP spoofing attack. However, they could not provide protection against the host impersonation and DoS attacks. This work introduces a new technique to secure address resolution protocol called ARP Authentication (ARP‐A). The proposed technique provides authentication for ARP messages and entities. In addition, it converts ARP from a stateless to a stateful protocol. To evaluate the performance of ARP‐A, it was implemented on Linux. To investigate the scalability of ARP‐A, a new analytical model was designed for it using stochastic reward nets. The results show that, compared with other related schemes introduced in the literature, ARP‐A is more efficient in terms of security and performance. 相似文献
Traffic lights have been installed throughout road networks to control competing traffic flows at road intersections. These traffic lights are primarily intended to enhance vehicle safety while crossing road intersections, by scheduling conflicting traffic flows. However, traffic lights decrease vehicles’ efficiency over road networks. This reduction occurs because vehicles must wait for the green phase of the traffic light to pass through the intersection. The reduction in traffic efficiency becomes more severe in the presence of emergency vehicles. Emergency vehicles always take priority over all other vehicles when proceeding through any signalized road intersection, even during the red phase of the traffic light. Inexperienced or careless drivers may cause an accident if they take inappropriate action during these scenarios. In this paper, we aim to design a dynamic and efficient traffic light scheduling algorithm that adjusts the best green phase time of each traffic flow, based on the real-time traffic distribution around the signalized road intersection. This proposed algorithm has also considered the presence of emergency vehicles, allowing them to pass through the signalized intersection as soon as possible. The phases of each traffic light are set to allow any emergency vehicle approaching the signalized intersection to pass smoothly. Furthermore, scenarios in which multiple emergency vehicles approach the signalized intersection have been investigated to select the most efficient and suitable schedule. Finally, an extensive set of experiments have been utilized to evaluate the performance of the proposed algorithm. 相似文献
We propose a novel framework for despeckling ultrasound image sequences while respecting the structural details. More precisely, we use thresholding in an adapted wavelet domain that jointly takes into account for the non-Gaussian statistics of the noise and the differences in spatial and temporal regularities. The spatiotemporal wavelet is obtained via the Kronecker product of two sparsifying wavelet bases acting, respectively, on the spatial and temporal domains. Besides enabling a structured sparse representation of the time–space plan, it also makes it possible to perform a variance stabilization routine on the spatial domain through a Fisz transformation. The proposed method enjoys adaptability, easy tuning and theoretical guaranties. We propose the corresponding algorithm together with results that demonstrate the benefits of the proposed spatiotemporal approach over the successive spatial treatment. Finally, we describe a data-driven extension of the proposed method that is based on temporal pre-filtering. 相似文献
In the present study, two-phase flow and forced-convection heat transfer of hydrogen gas (H2) in a solar finned and baffled channel heat exchanger (SFBCHE) is studied numerically. The effect of different obstacles in the channel is addressed. A H2 heat transfer fluid (HTF) having a high thermal conductivity with the baffling technique is implemented to enhance the overall performance of a solar channel. In the initial step, the results from the proposed numerical model were compared with the experimental data of a smooth channel, and then against data with a baffled channel. After checking the validity of our model, the same numerical approach was used for studying thermal-fluid characteristics of the channel with the new fluid. A hydrothermal analysis is presented for a range of Reynolds number (Re) from 5000 to 25,000. At the lowest Re = 5000, the thermal enhancement factor (TEF) is about 1.25. This value increases to 2.16, or 73.46%, when Re = 10,000. This increase in the TEF values continues as Re increases. The largest Re = 25,000 gives the highest TEF value, as it is about 4.18, which is 2.75 times greater than that given for the case of using the conventional gaseous fluid (air). Therefore, our proposed structure for the SFBCHE with high H2 HTF flow velocity leads to improve the values of dynamic pressure (Pd) and heat transfer (Nu), while reducing the skin friction (f) values, which increases the overall TEF of the channel. In addition, all performance values are greater than unity (or 1.00). This reflects the importance of the H2 HTF baffling and finning technique in improving the hydrodynamic thermal-energy performance of solar heat exchangers. The suggested model of SFBCHE filled with an H2 HTF having a high thermal conductivity allows a considerable enhancement in the overall thermal performances which can be employed in various thermal types of equipment, such as solar energy receivers, automotive radiators, and cooling in chemical industries.
Despite good rigidity, braced frames have weak nonlinear behavior and inadequate distribution of ductility in stories, which cause significant structural damage. In this research, a seismic resistant system called coupled concentrically braced frame (CCBF) is developed to enhance the performance of braced frames by coupling them with a beam. In this case, the coupling beams are the primary source for ductility of the system, and after their yielding in more severe earthquakes, the structure continues to benefit from the ductility of the braces as the secondary source; therefore, the system has two-level behavior caused by different probable seismic excitations. In this case, in addition to maintaining the stiffness of the two concentrically braced frames, the coupling beams resist against the movement of the braced frames, and as a result, the stiffness of the system is increased. Therefore, lighter elements can be used to resist lateral loads. Linear and nonlinear analyses of CCBF, and its comparison with other braced frames, indicate that participation of the coupling beams provides an adequate stiffness and ductility. These frames have more stable nonlinear behavior than conventional ones and continue their nonlinear behavior even after fracture of coupling beams in severe earthquakes. 相似文献
N-(Arylmethyleneamino)phthalimides ( 2a–c ) carrying an o-substituent in the aryl group were prepared by the reaction of N-aminophthalimide with o-substituted benzaldehydes. The reaction of these compounds with Grignard reagents proceeded either by normal addition to one of the carbonyl groups to give 3a–c or by addition and cleavage to give 4-arylphthalaz-1-ones 5a–c . The steric effect exhibited by either the Grignard reagent or the N-arylmethylene compound was studied. The reaction of N-furfurylideneaminophthalimide ( 2d ) with Grignard reagents was also investigated. N-(Arylmethyleneamino)phthalimides reacted with primary amines to give N,N′-dialkylphthalamides ( 7a and b ) while the reaction with secondary amines gave ( 8a and b ). 相似文献
This article is focused on biopolymers as intelligent environmentally friendly polymers, the production processes, and coatings of biotextiles used in different industries for next generation environmental applications. Furthermore, classification and composition of biodegradable polymers, the theoretical techniques, and factorial experimental designs for the optimization of processes with intelligent biotextiles used as an alternative to commercial chemical-based textiles at reasonable cost with a zero to low environmental footprint are discussed. This article will also provide how these novel modeling methodologies will assist polymer designers in making the best decision. The present work also discusses how the fully biodegradable polymers support the textiles industry by decreasing the processing energy, material, and manufacturing costs. Finally, current development as well as potential future applications and trends of biodegradable polymers in modern biodegradable textiles industry will be presented. 相似文献