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Issue Info: 
  • Year: 

    2023
  • Volume: 

    53
  • Issue: 

    1
  • Pages: 

    69-79
Measures: 
  • Citations: 

    0
  • Views: 

    195
  • Downloads: 

    43
Abstract: 

In this paper, a novel risk-based, two-objective (technical and economical) optimal reactive Power dispatch method in a wind-integrated Power system is proposed which is more consistent with operational criteria.  The technical objective includes the minimization of the new voltage instability risk index. The economical objective includes cost minimization of reactive Power generation and active Power loss. The proposed voltage instability risk employs a hybrid possibilistic (Delphi-Fuzzy)-probabilistic approach that takes into consideration the operator’s experience, the wind speed and demand forecast uncertainties when quantifying the risk index. The decision variables are the reactive Power resources of the system. To solve the problem, the modified multi-objective particle swarm optimization algorithm with sine and cosine acceleration coefficients is utilized. The method is implemented on the modified IEEE 30-bus system. The proposed method is compared with those in the previously published literature, and the results confirm that the proposed risk index is better at estimating the voltage instability risk of the system, especially in cases with severe impact and low probability. In addition, according to the simulation results compared to typical security-based planning, the proposed risk-based planning may increase the security and economy of the system due to better utilization of system resources.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    11
  • Issue: 

    1
  • Pages: 

    35-40
Measures: 
  • Citations: 

    0
  • Views: 

    19
  • Downloads: 

    0
Keywords: 
Abstract: 

In this paper, a new method for extending and relaxing the noise-coupling (NC) technique is proposed to enhance the noise-shaping order without adding the number of integrators. The noise-shaping order of the introduced ∑∆ modulator whit applying a second-order noise-coupling technique is enhanced and its performance with optimizing the noise transfer function (NTF) zeros is improved. Also, by removing the analog adder at feedforward path and transferring it to a new feedback branch before the last integrator and adding second-order NC path can be decreased the input voltage swing to the quantizer. Thus, by improving the modulator resolution, Power consumption can be reduced. Mathematical analyses and behavioural simulation results confirm the effectiveness of the new NC method. To examine its performance, a 2nd-order single loop ΣΔ modulator was designed. The new noise-coupling method is used to achieve the three-order noise shaping to increase the resolution with low complexity and low-Power. The results show an outstanding improvement in signal-to-noise and distortion ratio (SNDR) compared to the conventional structure.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    1401
  • Volume: 

  • Issue: 

  • Pages: 

    221-234
Measures: 
  • Citations: 

    0
  • Views: 

    75
  • Downloads: 

    0
Abstract: 

محاسبه حجم نمونه ی مناسب، توجیه آن و تحلیل توان در پژوهش های علوم روان شناختی دشوار است. فرایند تعیین حجم نمونه با استفاده از فرمول، بدون یک پیشینه آماری قوی دشوار است. میزان اطلاع دهندگی یک پژوهش بستگی به این توجیه دارد. هرچه میزان داده های گردآوری شده فزون تر شود، پژوهش مورد نظر با توجه به اهداف استنباطی که دارد، اطلاع دهندگی بیشتری خواهد داشت در این مقاله ابتدا به مرور مفاهیم پایه و سپس به معرفی خلاصه نرم افزار G*Power در تحلیل توان و تعیین حجم نمونه پرداخته شد. در پایان سه مثال کاربردی برای تعیین حجم نمونه همراه با مراحل اجرای نرم افزار آنها آوررده شد. نرم افزار G*Power به سادگی از تعیین حجم نمونه و تحلیل توان برای تمامی روش های آماری پشتیبانی می کند. از جمله این روش ها آزمون دقیق، آزمونهای تی، آزمونهای اف، آزمون های کای-اسکویر وآزمون های زی. هریک از این خانواده آزمونها شامل روش های آماری زیادی هستند. این نرم افزار، نرم افزاری کاربر پسند و مفید برای برآورد حجم نمونه و تحلیل توان در پژوهش های علوم روان شناختی است. این مقاله بینشی برای پژوهشگر روانشناختی فراهم می آورد به گونه ای که او بتواند این نرم افزار را برای دیگر روش های آماری نیز به کار ببرد.

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Issue Info: 
  • Year: 

    2019
  • Volume: 

    -
  • Issue: 

    56
  • Pages: 

    3-14
Measures: 
  • Citations: 

    0
  • Views: 

    616
  • Downloads: 

    0
Abstract: 

Turbochargers are used to increase engine manifold air pressure. Control of intake manifold pressure is crucial issue which is done through the speed control of turbocharger, but since it is difficult to directly control the speed of the turbocharger, it is done indirectly through a gate that called the waste gate, which is located in the engine outlet and turbocharger’ s turbine inlet. One of the most common control methods for control of turbocharger is the gain scheduling control. This method design in parameter look-up table, supervisor and system subsection to control turbocharger performance. The performance of control loop can be evaluated with accuracy of considered model and designed controller. In this paper, the engine model with the turbocharger has been created in the GT-Power software, then, by defining the input and output parameters in the GT-Power model, the model is coupled with MATLAB software to controller design. In the next step, two methods have been developed to design the controllers for the gain scheduling control method. Eventually, effectiveness of turbocharger control using gain scheduling control is shown.

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Issue Info: 
  • Year: 

    1393
  • Volume: 

    14
Measures: 
  • Views: 

    1272
  • Downloads: 

    0
Abstract: 

لطفا برای مشاهده چکیده به متن کامل (PDF) مراجعه فرمایید.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    20
  • Issue: 

    2 (39)
  • Pages: 

    221-234
Measures: 
  • Citations: 

    2
  • Views: 

    103
  • Downloads: 

    0
Abstract: 

Appropriate sample size calculation, its justification, and Power analysis are too difficult in psychological sciences. The process of sample size calculation and Power analysis using statistical formulas, especially without any background is too difficult. The informativeness of research depends on this justification. The more collected data, the more informativeness according to its inferential goals. In this paper, basic concepts have been discussed and then, G*Power software was briefly introduced for sample size determinations and Power analysis. Briefly, 3 practical examples of the sample size calculations using this software were finally introduced. This software supports sample size calculation and Power analysis for various statistical methods including exact test, t-tests, F-tests, Chi-Square tests, and Z-tests, each of these family tests includes many statistical tests. This software is user-friendly and useful software for estimating sample size and Power analysis in psychological science research. This paper provides insight for a psychological researcher and it will make the researcher able to apply this software to other statistical tests.

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Issue Info: 
  • Year: 

    1394
  • Volume: 

    30
Measures: 
  • Views: 

    345
  • Downloads: 

    0
Abstract: 

لطفا برای مشاهده چکیده به متن کامل (PDF) مراجعه فرمایید.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    52
  • Issue: 

    1
  • Pages: 

    33-41
Measures: 
  • Citations: 

    0
  • Views: 

    115
  • Downloads: 

    28
Abstract: 

This paper proposes a 2.4 GHz active mixer without passive inductor for the transceiver system. Taking into account the design requirements of the mixer, a double-balanced down-conversion structure with active inductor and negative resistance is designed. The proposed mixer with 130 nm CMOS technology is designed and simulated using Cadence software at 1.5 V supply voltage. Although we had to compromise conversion gain with linearity, we were able to achieve very high conversion gain with average linearity. Based on the results of post-layout simulations, the conversion gain of 27.57 dB, IIP3 equal to -7.88 dBm, 1-dB compression point equal to -17.34 dBm and IIP2 equal to 44.22 dBm with Power consumption of 2.5 mW was obtained for the proposed mixer. The chip size without input and output pads is 95.18 µm × 117.68 µm, which leads to a chip area of 0.0112mm2.

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Journal: 

Journal of Dentistry

Issue Info: 
  • Year: 

    2007
  • Volume: 

    7
  • Issue: 

    3-4 (13)
  • Pages: 

    1-11
Measures: 
  • Citations: 

    0
  • Views: 

    970
  • Downloads: 

    0
Abstract: 

Statement of problem: "Power Bleaching" which is a new an in-office whitening technique with a combination of a whitening agent (peroxide) and an auxiliary (plasma-Arch light), has been claimed to be an effective and fast method in tooth bleaching. What is more important in using this method is the maintenance of the pulp health after tooth whitening.Purpose: The aim of this study was to evaluate the human pulpal response after bleaching with H2O2 38% and plasma-Arc light.Materials and method: Eighty seven sound first premolars from 27 patients were selected and divided into 3 groups of 29, based on the time intervals of histologic evaluation. In each group 9 teeth were considered as a control. Vitality tests were done before bleaching (base line) and in four intervals of 2, 7, 30 and 60 days, but histologic evaluation was performed in three intervals 2, 7 and 60 days. Immediately after extraction, apical one third of the roots were sectioned off and each specimen was placed in 10% buffered formalin solution for pulpal fixation. EDTA was used for decalcification and sections were prepared from each specimen and stained with H&E and subsequently assessed microscopically for the following criteria: Irregularities in the odontoblastic layer, the presence of inflammatory cell, vasodilatation and pulpal fibrosis. Data was analyzed using Friedman test and Wilcoxon test (a= 0.05). Results: There were significant differences between the 2 and 60 days groups and between 7 and 60 days groups with respect to inflammatory responses and vasodilatation (p<0.05).Comparison of the control and experimental groups of the 2 and 7 days revealed statistically significant differences in inflammation and vasodilatation (p<0.05). No patient had experienced sensitivity, after different bleaching periods.Conclusion: Bleaching of teeth with H2O2 38% and plasma-Arc light might cause slight to moderate pulp reactions after 2 and 7 days confined to the coronal pulp. However, the observed histological changes did not affect the overall health of the pulp tissue permanently.

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Issue Info: 
  • Year: 

    2021
  • Volume: 

    11
  • Issue: 

    2 (22)
  • Pages: 

    199-212
Measures: 
  • Citations: 

    0
  • Views: 

    1155
  • Downloads: 

    0
Abstract: 

Introduction: Today, maximizing the efficiency of fuels and increasing the output Power of diesel engines is considered inevitable due to the increasing need for energy resources, the reduction of fossil fuel resources, the need to maintain the environment, reduce air pollution, and limit the electricity supply and fuel supply. In the large cities of Iran, the problem of vehicle pollution is one of the main problems. The lack of proper fuel, soot filters, and absence of requirement for a technical inspection of diesel vehicles have led to an increase in mortality and the growth of lung cancer due to pollution. All of studies indicate that fossil fuels, despite the low cost of production, will increase the cost of both living and environment. A solution for this crisis is to reduce the sources of pollutant-producing sources from the source of these pollutants. In the internal combustion engines, the compression ratio and alternative fuels are two important factors affecting engine performance and exhaust emission. Materials and Methods: In this research, a one-dimensional computational fluid dynamics solution with GT-Power software was used to simulate a six-cylinder diesel engine to study the performance and exhaust emissions with different compression ratios and alternative fuels. The compression ratio was chosen to be 15: 1 to 19: 1 with an interval at unity. Alternative fuels such as (as base diesel), methanol, ethanol, diesel and ethanol, biodiesel and decane were selected. To modeling engine, first, all parts of the engine were introduced as a real six-cylinder engine, and then the required data were entered according to the actual engine conditions at the atmospheric pressure of one atmosphere. Before this investigation was carried out, a validation model for evaluation was done by experimental and simulation data. The validation results showed that software model error is acceptable and the model has a good capability of fitting and predicting. Results and Discussion: The engine performance was evaluated in terms of engine Power, engine torque, and specific fuel consumption at different engine compression ratio and fuel. The results showed that with increasing the compression ratio, brake Power and brake torque increased. Among the fuels used in this engine, the maximum brake Power and brake torque in the compression ratio of 19 with the decane fuel were 3. 86% higher than that the base fuel and the lowest value was awarded in the compression ratio of 15, with methanol fuel and it was equal with 56. 04%. The results indicated that by increasing compression ratio, the brake specific fuel consumption was reduced due to more Power than the fuel consumed in the engine. A fuel with lower heating value should be injected more mass to the engine. This will increase the brake specific fuel consumption. In this research, the decane fuel with a compression ratio of 19 with a reduction of 3. 72% had the lowest brake specific fuel consumption among other fuels. The CO emission from the engine largely depended on the fuel's properties, the availability of oxygen, the fuel mix with air, temperature, and turbulence inside the combustion chamber. The results highlighted that by increasing compression ratio, CO emission increased and CO emission in biodiesel fuel, with a compression ratio of 15, was decreased by 82. 37% compared to the base. CO2 emissions are not too harmful to humans, but they increase the potential for ozone depletion and global warming. With increasing compression ratio, CO2 and HC emissions increased for all fuels, CO2 emissions have risen up the base. The fuel heating mechanism, combustion temperature, oxygen content, and gas fuel availability are the most important factors in the formation of NOx. With increasing the compression ratio, the amount of NOX increases, which is due to the high temperature in the cylinder at a higher compression ratio. The viscosity and density of fuels have an effect on NOX emission, and because of the larger droplets of the fuel, it released NOX. The highest NOx emissions from biodiesel fuel are due to the high oxygen content of this fuel and the lowest NOx emissions from decane fuel, due to the low density of the fuel compared to other fuels. Conclusions: The results of this study showed that the decane fuel with a compression ratio of 19 in total had the best functional and pollutant characteristics among the six fuel used in this study. Therefore, this fuel can be the best alternative for diesel fuel.

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