Sharif Digital Repository

We study the simplest optomechanical system in the presence of laser phase noise (LPN) using the covariance matrix formalism. We show that for any LPN model with a finite correlation time, the destructive effect of the phase noise is especially strong in the bistable regime. This explains why ground-state cooling is still possible in the presence of phase noise, as it happens far away from the bistable regime. We also show that the optomechanical entanglement is strongly affected by phase noise  

Optomechanical and electromechanical cavities have been widely used in quantum memories and quantum transducers. We theoretically investigate the robustness of optomechanical and electromechanical quantum memories against the noise of the control laser. By solving the Langevin equations and using the covariance matrix formalism in the presence of laser noise, the storing fidelity of Gaussian states is obtained. It is shown that the destructive effect of phase noise is more significant in higher values of coupling laser amplitude and optomechanical coupling strength G. However, by further increasing the coupling coefficient, the interaction time between photons and phonons decreases below the... 

The noise generated by the propeller is one of the most important components of the vessels noise. Therefore, reducing this noise will significantly decrease the total noise of the vessel. Underwater noise of vessels has destructive effects on marine life. In addition, this noise affects the health and comfort of the crew and passengers of the ship. Moreover, high noise may cause warships to be detected easily. In this paper, first, common methods of noise reduction, including blade coating, modern propellers, propeller hub modification and ducted propellers are investigated. Then, relevant optimization methods are presented. Next, the effects of the geometric parameters like number of... 

Combination of three-dimensional (3D) IC technology and network on chip (NoC) is an effective solution to increase system scalability and also alleviate the interconnect problem in large-scale integrated circuits. However, because of the increased power density in 3D NoC systems and the destructive effect of high temperatures on chip reliability, applying thermal management solutions becomes crucial in such circuits. In this study, the authors propose a runtime distributed migration algorithm based on game theory to balance the heat dissipation among processing elements (PEs) in a 3D NoC chip multiprocessor. The objective of this algorithm is to minimise the 3D NoC system's peak temperature,... 

Combination of three-dimensional (3D) IC technology and network on chip (NoC) is an effective solution to increase system scalability and also alleviate the interconnect problem in large-scale integrated circuits. However, because of the increased power density in 3D NoC systems and the destructive effect of high temperatures on chip reliability, applying thermal management solutions becomes crucial in such circuits. In this study, the authors propose a runtime distributed migration algorithm based on game theory to balance the heat dissipation among processing elements (PEs) in a 3D NoC chip multiprocessor. The objective of this algorithm is to minimise the 3D NoC system's peak temperature,... 

The oxidation of sponge iron products and its destructive effects on iron content as well as other properties have been considered by ferrous technologists for a long time. In this investigation, a unique new low temperature method of preventing and/or retarding the oxidation of direct reduced iron is introduced. Experimental results from laboratory and pilot plant tests show the success of the method which has been named cold briquetting of sponge iron. The optimum condition for briquetting is achieved at 80 kN (Lcm)-1, 6% binder, 10% sponge iron fines and 4% anthracite. While hot briquetted iron has become a successful method for the new generation of iron reduction plants, cold... 

In this paper the structure of Maximum Likelihood (ML) CFAR for lognormal clutter is derived assuming that some reference samples are censored to avoid destructive effect of interfering targets. It is shown that under some acceptable approximations we will achieve in a simple structure for this detector which is suitable for real time processing. The proposed detector is compared with non censored ML CFAR (i.e. logt CFAR) via simulation. It is shown that while the proposed detector is a little weaker than logt CFAR in homogeneous clutter, in non homogeneous clutter it outperforms the logt CFAR  

The performance of the resolver as a position sensor is significantly influenced by electrical and mechanical faults. Among different faults, short circuit in the stator windings has more destructive effect than others on accuracy of resolver. Furthermore, due to thin wires of the stator it is highly likely to occur. Therefore, in this paper a robust design is proposed for wound-rotor resolvers to not only suppress the influence of short circuit fault in the stator/rotor winding, but also improve the accuracy of the sensor under mechanical faults. The effectiveness of the proposed robust design is demonstrated by an analytical model based on winding function method and then approved by time... 

We have developed an analytic approach to investigate the effect of group delay ripple of the dispersive devices on the performance of two major building blocks of microwave- photonic filters. Firstly, performance of PM-based block in the presence of an arbitrary group delay ripple (GDR) is analyzed and compared with the ripple-free case to reveal the destructive effects of added group delay ripple. In the next step, we repeat the proposed approach for the AM-based one; again, the performance is compared with the ripple-free case. Two distortion metrics are also introduced to quantify this distortion. Comparison of the performance of two building blocks in the presence of group delay ripple... 

This paper presents the influence of the severe shot peening process on the fatigue life of the laser-cladded Inconel 718 specimens which can be employed during refurbishment of components enduring high mechanical cyclic loads such as gas turbine components. In order to quantitatively evaluate the destructive effect of laser cladding on the fatigue endurance, fatigue tests are first performed on the as-received and laser-cladded specimens. Then, microstructural analysis by scanning electron microscope (SEM) is carried out to identify the root causes of the drawback of laser cladding. Moreover, by employing a comprehensive laser-cladding FE analysis considering cyclic plastic material... 

The performance of the resolver as a position sensor is significantly influenced by electrical and mechanical faults. Among different faults, short circuit in the stator windings has more destructive effect than others on accuracy of resolver. Furthermore, due to thin wires of the stator it is highly likely to occur. Therefore, in this paper a robust design is proposed for wound-rotor resolvers to not only suppress the influence of short circuit fault in the stator/rotor winding, but also improve the accuracy of the sensor under mechanical faults. The effectiveness of the proposed robust design is demonstrated by an analytical model based on winding function method and then approved by time... 

Extreme weather events such as earthquake and hurricane have disastrous consequences on power systems. Due to the inherent nature of these events, as high-impact low-probability (HILP) events, selection of an appropriate method that can provide the effects of weather conditions on the power system behavior still remains a significant challenge. Resilience is a new concept that focuses on mitigating the destructive effects of such disastrous events on power systems. This article provides a fundamental framework for quantifying and modeling of power systems resilience, with focus on high wind incidence. The algorithm composes of four steps. In the first step, the prerequisites of the analysis... 

Gas flooding is a practical secondary scenario for enhanced oil recovery. Channeling and fingering of the injected gas are the major problems facing this technique. These challenges can be mitigated by the injection of gas as foam. However, foam stability influences the overall efficiency of the process, which could be improved by nanoparticles (NPs). This work provides a theoretical and experimental analysis of the NPs wettability effects on foam behavior, in both static and dynamic states. The treated calcite (CaCO3) NPs along with a cationic surfactant (HTAB) were used for this purpose. By comparison of theoretical and experimental data, it was shown that the foam stability in the... 

Dynamic loads in many projects cause vibration in soil. The propagated energy has a destructive effect on the foundation of the adjacent structures. One of the suitable methods for preventing these harmful waves is active isolation. In this paper the mentioned phenomena is studied by conducting some physical model tests. The loose sandy models are excited by impact type load of a tamper and the response for models with and without trench are measured at different points. Two types of closed form or continuous trenches are used. In closed form trench models, the effect of trench on acceleration attenuation and the ratio of vertical to horizontal accelerations were investigated. In continuous...