Papers by mohammad rashidi
Airfield and Highway Pavements 2019, 2019
2017 IEEE Energy Conversion Congress and Exposition (ECCE), 2017
The challenge of failure management emerges in decentralized architectures due to the distributed... more The challenge of failure management emerges in decentralized architectures due to the distributed nature of the layered control process. Failures in microgrid system may occur at the microgrid level or any of the control layers. A failure detection and response mechanism is required to attain a reliable, fault-tolerant microgrid operation. This paper introduces a Failure Management Unit as an essential function in a microgrid Energy Management System. The proposed unit comprises failure detection mechanisms and a recovery algorithm. The proposed system is applied to a microgrid case study and shows a robust detection and recovery outcome during a system failure. The real-time experimental results were achieved using Hardware-In-the-Loop platform. Coordination between controllers during the recovery period requires low-bandwidth communications, which has no significant overhead on the communication infrastructure.
2017 IEEE 6th International Conference on Renewable Energy Research and Applications (ICRERA), 2017
Development of the new generation of high power and high frequency power electronic switches alon... more Development of the new generation of high power and high frequency power electronic switches along with the need for compact controllable converters for utilization of distributed energy resources in the grid, have led to significant developments in the area of solid state transformers in the last years. The design process of a high frequency transformer as the main element in the solid state transformer is illustrated in this article. A multi winding transformer for multiport SST application is designed, studied and built in this research. In a MPSST several windings feed the core. As the result, coupling coefficient between each pair of windings, become an important factor which is studied in this study. Since the transformer is designed for high frequency applications, the power loss in the wire and core of the transformer increases as the result of higher skin effect and eddy current loss in high frequency. Three important factors in the design of HF transformer for MPSST are discussed in the paper. First, four different possible core materials are compared based on their flux density, frequency range, loss and price. Then the cable selection is illustrated and finally, different winding placement and distribution on the same core are suggested and the inductance and coupling coefficient matrices are calculated using ANSYS Maxwell 3D simulation. The transformer is built in the lab and the inductance values matches the expected values from the simulation.
Bulletin of the American Physical Society, 2018
2017 IEEE Power & Energy Society General Meeting, 2017
Distribution systems need significant voltage support with growing penetration of distributed gen... more Distribution systems need significant voltage support with growing penetration of distributed generations especially intermittent renewable energy resources and smart loads. This paper introduces the application of the Multi-Port Solid State Transformer (MPSST) as an effective tool to support grid voltage at distribution level while integrating distributed energy resources. The solid state transformer replaces the conventional transformer between two voltage zones of distribution systems. Matlab/Simulink environment is used to simulate the IEEE 14 bus test system with an MPSST as a case study. The simulation results prove the effectiveness of the MPSST supporting the distribution system at local level in a fast and efficient manner in response to disturbances caused by load variations.
Bulletin of the American Physical Society, 2012
Bulletin of the American Physical Society, 2019
European Journal of Experimental Biology, 2013
The accumulation of an enormous amount of lactic acid in the blood is one of the causes of exhaus... more The accumulation of an enormous amount of lactic acid in the blood is one of the causes of exhaustion for athletes after vigorous exercises, particularly short time exercises with the maximum of speed and intensity. Considering the need of athletes to reach the natural conditions and to be ready for subsequent activities, methods of lactic acid disposal are of high importance. The purpose of this study was to determined The effect of high intensity anaerobic training on the blood lactate levels after recovery. This quasi-experimental research, pre-tested and post tested 60 male athlete students. The athletes randomly were divided into four groups of 15 including the first group to do initial inactive recovery, the second to fourth to do initial active retrieval with the intensity of 55, 60, 65 percent Maximum heart beat . The groups were evaluated by Cunningham test and their blood lactic acid was checked in four phases by manual lactometer( before activity, immediately after the ac...
ntroduction: Obesity is a major risk factor for inflammation and cardiovascular diseases. We trie... more ntroduction: Obesity is a major risk factor for inflammation and cardiovascular diseases. We tried to assess whether 12 weeks of aerobic exercises affect serum resistin level and lipid profile in overweight females or not.MethodsFor this purpose, 32 non-trained adult females with the mean age of 38 ± 7 years old and body mass index (BMI) of 32 ± 3 kg/m2 were randomly assigned to aerobic exercise (n=16) and control (n=16) groups. Twelve weeks of aerobic exercise program including 3 sessions weekly at 60-75% of maximum heart rate was considered. Fasting serum resistin level, lipid profile (total cholesterol [TC], low-density lipoprotein [LDL] and high-density lipoprotein [HDL] cholesterol, and triglyceride [TG]), and anthropometric indexes were measured and compared between the two groups before and after training.ResultsSerum resistin, lipid profile markers, and anthropometrical indexes were not significantly different at baseline between the two groups (P > 0.05). TG, TC, LDL, an...
Journal of Advances in Medical and Biomedical Research, 2020
10.30699/jambs.28.130.291 Background & Objective: Candida species, and most frequently isolated C... more 10.30699/jambs.28.130.291 Background & Objective: Candida species, and most frequently isolated Candida albicans, are normal microorganisms of oral cavities; however, C. albicans is responsible for oral cavities in children with dental caries. As a new biologic technique, using probiotics has gained popularity in preventing and controlling diseases at present. Enterococcus durans has exhibited useful antioxidative properties and antibacterial and probiotic characteristics. This study aims to evaluate the effects of probiotic Enterococcus durans on the in vitro adhesion of Candida albicans. Materials & Methods: Reference bacteria strain of probiotic E. durans (ATCC 6056), C. albicans reference strain (PTCC-5027), and 10 clinical samples of C. albicans were provided. Adherence inhibition of Candida albicans was measured using microtiter plates applying two methods (addition of a mixed suspension of C. albicans and E. durans simultaneously and addition of E. durans 30 minutes before C. albicans). Data were analyzed with a repeated measure model. Statistical significance was set at P-value<0.01. Results: Adhesions of C. albicans biofilms decreased in the presence of the probiotic strain E. durans. Mean OD620 nm was within the range of 0.45 to 0.49, and 0.33 for OD490 nm. Conclusion: Using E. durans as a probiotic could reduce Candida albicans adhesion and, therefore, can be considered as an effective way to decrease its pathogenicity.
IET Optoelectronics, 2020
Global Journal of Civil Engineering, 2019
Maintaining and restoring buildings has nowadays gained special importance due to its high cost. ... more Maintaining and restoring buildings has nowadays gained special importance due to its high cost. Various different methods have been presented regarding this matter due to the above-mentioned reason and also the ever-growing demand for the engineers and the building-industry specialists for strengthening, restoring, and improving the concrete structures. The effect of FRP sheets on shear and flexural strengthening of simple concrete beams has been examined in this research. Four concrete beams containing concrete were constructed with a similar cross section and length and a common resistance level. They underwent the two-point flexural test and their exploitation conditions were studied. The results showed that if the FRP sheets are used appropriately and with proper bracing in strengthening the concrete beam samples, there will be a significant increase in their shear and flexural strength. Moreover, it was observed that relative deformation measured on the concrete surface and th...
IEEE Transactions on Industry Applications, 2019
In this study, a four-port solid-state transformer (SST) and a control scheme to control the powe... more In this study, a four-port solid-state transformer (SST) and a control scheme to control the power flow and output voltage is studied, developed and tested. The converter consists of three ports with H-bridge converters and one port with diode bridge rectifier. The ports with H-Bridge converters are capable of bi-directional power routing as well as reactive power contribution in a Volt/VAR control scenario. The diode bridge rectifier provides a DC voltage for load connection. Different arrangements for the four transformer windings are analyzed, simulated and compared to achieve an optimal design. A new control strategy, which uses a combination of phase-shift and duty cycle control, is employed to control the flow of power between the converter branches and to regulate the output voltage. While phase-shift control ensures the balance of power on each port based on a reference value, the duty cycle control keeps the load voltage at a desired voltage level. A high-level control scheme is employed to determine the power references for all ports according to the load demand, generation capacity of the distributed generation system, and state of charge of the energy storage. The performance of the proposed system is validated with simulation and experimental analysis. A prototype is designed and built with 10 kW power rating at each port. The operating frequency of the system is designed at 100kHz to obtain a very compact size for the whole converter.
Surface Science, 2018
Single-molecule chemical reduction induced by low-temperature scanning tunneling microscopy: a ca... more Single-molecule chemical reduction induced by low-temperature scanning tunneling microscopy: a case study of Gold-porphyrin on Au(111),
Nature Communications, 2018
At the atomic scale, there has always been a trade-off between the ease of fabrication of structu... more At the atomic scale, there has always been a trade-off between the ease of fabrication of structures and their thermal stability. Complex structures that are created effortlessly often disorder above cryogenic conditions. Conversely, systems with high thermal stability do not generally permit the same degree of complex manipulations. Here, we report scanning tunneling microscope (STM) techniques to substantially improve automated hydrogen lithography (HL) on silicon, and to transform state-of-the-art hydrogen repassivation into an efficient, accessible error correction/editing tool relative to existing chemical and mechanical methods. These techniques are readily adapted to many STMs, together enabling fabrication of error-free, room-temperature stable structures of unprecedented size. We created two rewriteable atomic memories (1.1 petabits per in2), storing the alphabet letter-by-letter in 8 bits and a piece of music in 192 bits. With HL no longer faced with this trade-off, practi...
Journal of Fluids Engineering, 2018
Shear stress transport (SST) k–ω model and detached eddy simulation (DES) have been widely applie... more Shear stress transport (SST) k–ω model and detached eddy simulation (DES) have been widely applied in crosswind stability simulations for trains in the literature. In the previous research, the influence of the SST and DES approaches on the flow field around trains, which affects the surface pressure and consequently the aerodynamic forces of the train, was not properly investigated in terms of their influence flow field. The SST and improved delayed detached eddy simulation (IDDES) turbulence models have been tested in this study for their ability to predict the flow field around, surface pressure, and aerodynamic forces on a 1/25th scale Class 390 train subjected to crosswinds. Numerical simulation results were validated with experimental data. Results show that both SST and IDDES predict similar trends in the mean flow field around the train. However, there were some slight differences observed in the size of vortices, the position of separation points, and consequently, the sepa...
ACS nano, Jan 23, 2018
Atomic-scale characterization and manipulation with scanning probe microscopy rely upon the use o... more Atomic-scale characterization and manipulation with scanning probe microscopy rely upon the use of an atomically sharp probe. Here we present automated methods based on machine learning to automatically detect and recondition the quality of the probe of a scanning tunneling microscope. As a model system, we employ these techniques on the technologically relevant hydrogen-terminated silicon surface, training the network to recognize abnormalities in the appearance of surface dangling bonds. Of the machine learning methods tested, a convolutional neural network yielded the greatest accuracy, achieving a positive identification of degraded tips in 97% of the test cases. By using multiple points of comparison and majority voting, the accuracy of the method is improved beyond 99%.
Journal of visualized experiments : JoVE, Jan 19, 2018
The miniaturization of semiconductor devices to scales where small numbers of dopants can control... more The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new techniques capable of characterizing their dynamics. Investigating single dopants requires sub-nanometer spatial resolution, which motivates the use of scanning tunneling microscopy (STM). However, conventional STM is limited to millisecond temporal resolution. Several methods have been developed to overcome this shortcoming, including all-electronic time-resolved STM, which is used in this study to examine dopant dynamics in silicon with nanosecond resolution. The methods presented here are widely accessible and allow for local measurement of a wide variety of dynamics at the atomic scale. A novel time-resolved scanning tunneling spectroscopy technique is presented and used to efficiently search for dynamics.
Applied Optics, 2017
This paper presents a computational and semi-analytical approach for theoretical evaluation of so... more This paper presents a computational and semi-analytical approach for theoretical evaluation of solution-process-based optoelectronic devices, such as quantum dot (QD) infrared photodetectors. The dark current and photocurrent for infrared photodetectors are extracted on the basis of the model presented here. In this model, two main mechanisms have been assumed to contribute to the current of the device: the electron tunneling in the confined states and the drift of electrons in the continuum states. For the former, the Landauer-Büttiker formalism, in which the transmission function was obtained through the Green&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s function method was used. However, the drift-diffusion model was applied for the latter while considering the trapping and detrapping roles of QDs. Furthermore, different geometrical effects have been analyzed, including the QDs&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; size distribution, the space between QDs, the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s length, and the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s width, on the device&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s parameters, such as the absorption coefficient, photoconductive gain, dark current, and detectivity. The results seem to point to a great dependency of the device&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s performance on these geometrical aspects. For example, the nonuniformity of the QDs&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; sizes have been shown to exert negative effects on the device&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s detectivity. In addition, it could noticeably influence the tunneling current, such as by decreasing the maximum value of the current.
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Papers by mohammad rashidi