Sharif Digital Repository

Nitrates of lithium, cobalt and nickel are utilized to synthesize LiNi 0.8Co0.2O2 cathode material through sol-gel technique. Various synthesis parameters such as calcination time and temperature as well as chelating agent are studied to determine the optimized condition for material processing. Using TG/DTA techniques, the optimized calcination temperatures are selected. Different characterization techniques such as ICP, XRD and TEM are employed to characterize the chemical composition, crystal structure, size and morphology of the powders. Micron and nano-sized powders are produced using citric/oxalic and TEA as chelating agent, respectively. Selected powders are used as cathode material... 

In this paper, we consider the problem of sensor placement for passive source localization under conditions where there are multiple sources and noise measurement is distance dependent. To this end, first we derive the Cramer-Rao bound for the angle of arrival (AOA) based source localization for distance-dependent noise model and existence of multiple sources. Then, the optimal arrangement of sensors to achieve this bound is obtained  

In this paper, the problem of obtaining the optimal trajectory of a Dual-Arm Cam-Lock (DACL) robot is addressed. The DACL robot is a reconfigurable manipulator consisting of two cooperative arms, which may act separately. These may also be cam-locked in each other in some links and thus lose some degrees of freedom while gaining higher structural stiffness. This will also decrease their workspace volume. It is aimed to obtain the optimal configuration of the robot and the optimal joint trajectories to minimize the consumed energy for following a specific task space path. The Pontryagin's Minimum Principle is utilized with a shooting method to resolve kinematic redundancy. Numerical examples... 

In this paper, the problem of obtaining the optimal trajectory of a Dual-Arm Cam-Lock (DACL) robot is addressed. The DACL robot is a reconfigurable manipulator consisting of two cooperative arms, which may act separately. These may also be cam-locked in each other in some links and thus lose some degrees of freedom while gaining higher structural stiffness. This will also decrease their workspace volume. It is aimed to obtain the optimal configuration of the robot and the optimal joint trajectories to minimize the consumed energy for following a specific task space path. The Pontryagin's Minimum Principle is utilized with a shooting method to resolve kinematic redundancy. Numerical examples... 

The flow field in axial turbines is complex and threedimensional. Therefore, experimental flow field is essential to determine the performance characteristics. However, such testing is always expensive and complex. Simulation of gas turbines is a simple way to reduce testing costs and complexity. The main objective of this paper is to make a detailed systematic analysis of two-stage, axial flow turbine by using of different loss models and a new suggested algorithm based on one-dimensional simulation. In one-dimensional modeling, the loss models have to be used to determine the entropy increase across each section of axial turbines stage at both the design and off-design conditions. The... 

Digital Elevation Models (DEMs) play a significant role in hydraulic modeling and flood risk management. This study initially investigated the effect of Unmanned Aerial Vehicle (UAV) DEM resolutions, ranging from 1 m to 30 m, on flood characteristics, including the inundation area, mean flow depth, and mean flow velocity. Then, the errors of flood characteristics for global DEMs, comprising ALOS (30 m), ASTER (30 m), SRTM (30 m), and TDX (12 m) were quantified using UAV DEM measurements. For these purposes, the HEC-RAS 2D model in steady-state conditions was used to simulate the flood with return periods of 5- to 200 years along 20 km reach of Atrak River located in northeastern Iran.... 

The main objective of this paper is to make a detailed systematic analysis of two-stage, axial flow turbine by using of different losses models and a new suggested algorithm based on one-dimensional simulation. The suggested method is found to be effective, fast and stable, in obtaining performance characteristics of multi-stage axial flow turbines. In one-dimensional modeling, mass flow rate, pressure ratio and efficiency are unknown, with define turbine geometry, inlet total pressure and temperature the turbine performance characteristics can be modeled. This modeling is based on common thermodynamics and aerodynamics principles in a mean stream line analysis under steady state condition.... 

The aim of present research is the performance simulation of axial flow turbine on different operating conditions by using of one dimentional modeling method. In this method by receiving the flow inlet conditions and turbine geometry, velocity triangles at blade inlet and outlet are obtained and performance characteristics of the turbine are calculated. As respects the importance of modeling for performance prediction and optimization in initial desing level, in following work, that is based on one dimentional modeling method, after the presentation of solution algorithm by trial and error method and introduction of different loss models for modeling, the obtained results of modeling were... 

In the present study, the tri-layer nanofibers were synthesized via triaxial electrospinning process to control the sustained delivery of Doxorubicin (DOX), Paclitaxel (PTX) and 5- fluorouracil (5-FU) anticancer drugs from nanofibers. The 5-FU molecules were incorporated into the core solution (chitosan/polyvinyl alcohol (CS/PVA)) to fabricate the CS/PVA/5-FU inner layer of nanofibers. The intermediate layer was prepared from poly(lactic acid)/chitosan (PLA/CS) nanofibers. The DOX and PTX molecules were initially loaded into the g-C3N4 nanosheets and following were incorporated into the PLA/CS solution to fabricate the outer layer of nanofibers. The synthesized nanosheets and nanofibers were... 

Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network...