Sharif Digital Repository

Laser shock peening (LSP) is known as a post processing surface treatment which can improve the mechanical properties of some materials. Shock waves are generated by confining the laser-induced plasma to cause a large pressure shock wave over a significant surface area. In the present study, effects of LSP on the electrochemical corrosion and micro hardness properties of 316L stainless steel alloy were investigated by changing the laser parameters such as the laser spot size, the average number of impacts, and the laser intensity. Since laser parameters do not cover the desired region of LSP, we have to use the proper design of experiment method, in which the D-optimal design of MATLAB was... 

The potential of end-users to modify their consumption pattern makes them an interesting resource for providing energy flexibility in energy communities. Thus, active end-users require sufficient incentives and automated trading and management schemes. In order to enable increased small-scale end-users participation for flexibility service provision, a new design for flexibility trading is required to model the behavior of different agents and their interactions in energy communities. The novelty of our work lies in proposing an iterative game-based approach in which all agents - consisting of the distribution system operator (DSO), aggregators, and customers- can determine their decision... 

Rheological models for polymer solutions and melts based on the finitely extensible non-linear elastic (FENE) dumbbell theory are reviewed in this study. The FENE-P model that is a well-known Peterlin approximation of the FENE model, indicates noticeable deviation from original FENE predictions and also experimental results, especially in the transient flow. In addition, both FENE and FENE-P models have some shortcomings from the point of view of theory. To overcome these shortcomings, a new approximation of the FENE spring force has been established. It has been used to develop a modified constitutive rheological model for polymeric fluids. In the procedure of modeling, the effect of... 

Purpose: Although it has been proposed that individuals with patellofemoral pain show less lower limb intersegmental coordination variability, the evidence to support this hypothesis is rare. The purpose of this study was, therefore, to evaluate whether individuals with patellofemoral pain exhibit less intersegmental coordination variability compared with healthy individuals during walking and running. Also, it was hypothesized that increasing task demand would exacerbate group differences regarding coordination variability measures. Methods: Three-dimensional kinematics were collected while 17 females with patellofemoral pain and 17 healthy females walked at preferred speed, and ran at... 

Purpose: There is a scarcity of studies evaluating the variability of couplings between proximal segments (trunk, pelvis, and thigh) in individuals with patellofemoral pain (PFP) while emerging evidence has suggested that aberrant motions of trunk and pelvis can have a contributory role in the etiology of PFP. The purpose of this study was, therefore, to evaluate the trunk, pelvis, and thigh intersegmental coordination variability in PFP compared with healthy individuals. Methods: Thirty-four participants (17 with PFP and 17 healthy controls) walked (at preferred speed) and ran (at preferred and fixed speed) on a treadmill each trial for 30 seconds. Three-dimensional kinematics were recorded... 

In the original publication, there were errors in some sentences, Figure legends, and Tables that are corrected as below:. © 2021, Taiwanese Society of Biomedical Engineering  

Presently, the urgency of creating efficient system to tackle natural hazards such as tsunamis, earthquakes, landslides and floods to cite just a few, have originated that Wireless Sensor Networks (WSNs) play an increasingly important role in the natural hazards scenario as an efficient early warning system, sometimes in synergy with satellites-GMES (Global Monitoring Earth Systems) and also with mobile robotics. Their integration into the web scenario, giving rise to the sensor-web technology, provides even more power to the intrinsic strengths of WSNs. The WSNs application in post-disaster scenarios is also an emerging challenging issue. In this paper the fundamental technology concepts of... 

Computation of the acoustic disturbances generated by unsteady low-speed flow fields including vortices and shear layers is considered. The equations governing the generation and propagation of acoustic fluctuations are derived from a two-step acoustic/viscous splitting technique. An optimized high order dispersion-relation-preserving scheme is used for the solution of the acoustic field. The acoustic field generated by a corotating vortex pair is obtained using the above technique. The computed sound field is compared with the existing analytic solution. Results are in good agreement with the analytic solution except near the centre of the vortices where the acoustic pressure becomes... 

The tip-loaded propeller design is one of the new methods for improving propellers' hydrodynamic and acoustic performance. This study investigates the effects of different endplate geometries on the performance of a 5-blade B-series propeller with normal skew and rake using the RANSE numerical method. For each of the different geometries, hydrodynamic coefficients, cavitation volume, and propeller noise are calculated. Using an endplate, this research aims to reduce cavitation, tip vortex, and propeller noise. As a result of the research, propellers with a contraction of 0.95R and a flap angle of 60°, as well as propellers with a contraction of 0.9R and a flap angle of 60°, showed better... 

Switched Reluctance Motors (SRMs) are widely used in high-speed and low voltage applications because of their attractive features such as robustness and simplicity. No winding on the rotor of this type of motors allows reaching high speed which is desired for many applications. Drive circuits of SRMs also play an important role in their performance and operation. In this paper, a new bifilar drive circuit for this type of motors has been proposed. This novel configuration has been tested and investigated by PSIM software. Results show that the new bifilar drive circuit highly reduces the voltage stresses on semiconductor switches, and also considerably reduces the switching losses which are... 

Fabricating a multifunctional orthopedic implant which prevents post-surgery infection is highly desirable in advanced materials applications. However, designing an antimicrobial implant, which simultaneously promotes a sustained drug release and satisfactory cell proliferation, remains a challenge. The current study presents a drug-loaded surface-modified titanium nanotube (TNT) implant with different surface chemistry which was developed to investigate the effect of surface coating on drug release, antimicrobial activity, and cell proliferation. Accordingly, sodium alginate and chitosan were coated on the surface of TNT implants with different coating orders through layer-by-layer... 

This paper represents a systematic procedure of simulating charge pump based delay locked loops (DLLs). The presented procedure is based on the systematic modelling of the DLL components in Matlab simulink simulator. The system has been designed for 1Hz input clock signal that by changing the whole system scale, it can be used for every other input frequencies. The simulation results in Matlab and design considerations for DLL based frequency multiplier are presented  

Benefitting from an analogy between compressible and incompressible governing equations, a novel dual-purpose, pressure-based finite-volume algorithm is suitably extended to simulate laminar mixing and reacting flows in low-Mach-number regimes. In our test cases, the Mach number is as high as 0.00326. Definitely, such low-Mach-number flows cannot be readily solved by either regular density-based solvers or most of their extensions. To examine the accuracy and performance of the extended formulation and algorithm, we simulate two benchmark cases including the mixing natural-convection flow in a square cavity with strong temperature gradients and the premixed reacting flow through annuli with... 

Noise generated by ships is one of the most significant noises in seas, and the propeller has a significant impact on the noise of ships, which reducing it can significantly lower the noise of vessels. In this study, a genetic algorithm was used to optimize the hydro-acoustic and hydrodynamic performance of propellers. The main objectives of this optimization were to reduce the propeller noise and increase its hydrodynamic efficiency. Modifying the propeller geometry is one of the most effective methods for optimizing a propeller performance. One of the numerical methods for calculating propeller noise is the Ffowcs Williams and Hawkings (FW-H) Model. A numerical code was developed by... 

Regarding the increasing number of electrical devices in the smart homes that leads to increase in total electricity consumption and cost, it is essential to use energy management methods to reduce the electricity cost. However, this can cause resident's dissatisfaction. Hence, it is important to define a method in which cost and dissatisfaction be optimized simultaneously. Among different services, an electric vehicle is the one that can be used as an energy storage system, so it can reduce the daily cost despite of increasing the total energy consumption. In this paper, we study the effect of the EV on the cost and dissatisfaction in our proposed method. © 2018 IEEE  

In this study, initially graphene quantum dots (GQDs) were synthesized by an electrochemical technique and hierarchical porous TiO2 were made by a sol – gel method. Subsequently, GQDs/hierarchical porous TiO2 nanocomposites were prepared by two different methods for the purpose of comparison: spin coating (SC) and electrophoretic (EP) deposition. The GQDs/hierarchical porous TiO2 nanocomposites were characterized by various analytical methods including field emission scanning electron microscopy, atomic force microscopy, transmission electron microscopy, high resolution transmission electron microscopy, Fourier transform infra-red spectroscopy, photoluminescence spectroscopy and... 

The effect of equal channel angular pressing (ECAP) at different temperatures (room temperature, 120, 150 and 180 °C) on microstructure and mechanical properties of Al-7075 solid solution alloy was investigated. Microstructure of the specimens was examined using orientation imaging microscopy, transmission electron microscopy as well as X-ray diffractometer, and mechanical properties were measured by Vickers microhardness and tensile tests. Microstructural investigations showed that after 3 or 4 passes of ECAP, fine grains with average grain sizes in range of 300-1000 nm could be obtained at different ECAP temperatures. Increasing ECAP temperature from 120 to 180 °C caused a decrease in... 

In this paper, we present a scan-chain-based multiple error recovery technique for triple modular redundancy (TMR) systems (SMERTMR). The proposed technique reuses scan-chain flip-flops fabricated for testability purposes to detect and correct faulty modules in the presence of single or multiple transient faults. In the proposed technique, the manifested errors are detected at the modules' outputs, while the latent faults are detected by comparing the internal states of the TMR modules. Upon detection of any mismatch, the faulty modules are located and the state of a fault-free module is copied into the faulty modules. In case of detecting a permanent fault, the system is degraded to a... 

Inter-segmental coordination can be influenced by chronic low back pain (CLBP). The sagittal plane lower extremities inter-segmental coordination pattern and variability, in conjunction with the pelvis and trunk, were assessed in subjects with and without non-specific CLBP during free-speed walking. Kinematic data were collected from 10 non-specific CLBP and 10 non-CLBP control volunteers while the subjects were walking at their preferred speed. Sagittal plane time-normalized segmental angles and velocities were used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify the trunk-pelvis and bilateral... 

Ta0.8Hf0.2C ceramic has the highest melting point among the known materials (4000 °C). However, this high melting point makes the ceramic difficult to be sintered at temperatures lower than 2300 °C, pressurelessly. The purpose of this study is to consolidate Ta 0.8Hf0.2C UHTC by pressureless sintering at 2000 °C using MoSi2 as sintering aid. In this regard, effect of different amounts of MoSi2 on sintering behavior of Ta0.8Hf 0.2 UHTC was investigated. It was observed that condensation of the UHTC after sintering at 2000 °C was enhanced by increasing MoSi2 content and the highest relative density of 95% was obtained in the presence of 24 vol.% MoSi2. XRD pattern of the sintered UHTC...