Sharif Digital Repository

Data aggregation is a very important method to conserve energy by eliminating the inherent redundancy of raw data in dense WSNs. Although structured approaches are particularly useful for data gathering applications, they incur high maintenance overhead in dynamic scenarios for event-based applications. Moreover, a WSN should be capable of timely fulfilling its mission without losing important information in event-critical applications. In this paper, we focus on designing a structure-free Real-time data AGgregation protocol, RAG, using two mechanisms for temporal and spatial convergence of packets - Judiciously Waiting policy and Real-time Data-aware Anycasting policy. Using extensive... 

Lifetime is the most important concern in wireless sensor networks due to limited battery power of sensor nodes. In this paper, we focus on designing an energy-efficient and energy-aware routing algorithm, LLR, to increase the operational lifetime of multi-hop wireless sensor networks in the presence of unreliable communication links. Our proposed protocol utilizes a parameter, Broadcasting Delay, in each node associated with the hop parameters passed by a route request packet to select long lifetime paths in the network. The key point in Broadcasting Delay formulation is that it includes both node and link specific parameters. We use two different scenarios: either the link layer... 

In this paper a finite deformation constitutive model for rigid plastic hardening materials based on the logarithmic strain tensor is introduced. The flow rule of this constitutive model relates the corotational rate of the logarithmic strain tensor to the difference of the deviatoric Cauchy stress and the back stress tensors. The evolution equation for the kinematic hardening of this model relates the corotational rate of the back stress tensor to the corotational rate of the logarithmic strain tensor. Using Jaumann, Green-Naghdi, Eulerian and logarithmic corotational rates in the proposed constitutive model, stress-strain responses and subsequent yield surfaces are determined for rigid... 

In this paper a flow rule for rigid plastic hardening materials based on von Mises yield criterion is introduced. This flow rule relates the corotational rate of the logarithmic strain tensor to the difference of the deviatoric Cauchy stress and the back stress tensors. Using different corotational rates in the proposed flow rule, the deviatoric Cauchy stress tensor is calculated for rigid plastic isotropic, kinematic and combined hardening materials in the simple shear problem at large deformations. For the purpose of verification, the results for different corotational rates are compared with the results presented in referenced articles  

Lifetime is the mos important concern in Wireless Sensor Networks (WSNs) due to limited battery power of sensor nodes. Moreover, a WSN should be capable of timely fulfilling its mission without losing important information in event-critical applications. In this paper, we focus on designing an energy-efficient and energy-aware real-time routing algorithm aiming to explore the long lifetime routing schemes in which delay constraint is satisfied in the presence of lossy communication links. To achieve this goal, our energy-aware forwarding protocol utilizes an optimum distance real-time routing algorithm to minimize energy consumption in unreliable WSNs. Simulation results reveal that the...