The unsteady motion of a two-layer fluid induced by oscillatory motion of a flat plate along its length is mathematically analyzed. Two cases are considered: (i) the two-layer fluid is bounded only ...by the oscillating plate (Stokes’ second problem), and (ii) the two-layer fluid is confined between two parallel plates, one of which oscillates while the other is held stationary (oscillatory Couette flow). In each of the Stokes and Couette cases, both cosine and sine oscillations of the plate are considered. It is assumed that the fluids are immiscible, and that the flat interface between the fluids remains flat for all times. Solutions to the initial-boundary value problems are obtained using the Laplace transform method.The results obtained for the velocity fields for the flows are new and complete. Steady periodic and transient velocity fields are explicitly presented. Transient and steady-state shear stresses at the boundaries of the flows are calculated; the existing literature lacks any such results. The results derived in this paper retrieve previously known results for corresponding single-layer flows. Furthermore, the results obtained are illustrated taking particular example of each of the Stokes’ problem and the Couette flow. With the help of the illustrations, some physical insights into the flows of the particular problems are gained. Again, the results obtained could also be applicable to a problem of heat conduction in a composite solid with sinusoidal temperature variation on the surface.
A microgrid, regarded as one of the cornerstones of the future smart grid, uses distributed generations and information technology to create a widely distributed automated energy delivery network. ...This paper presents a review of the microgrid concept, classification and control strategies. Besides, various prospective issues and challenges of microgrid implementation are highlighted and explained. Finally, the important aspects of future microgrid research are outlined. This study would help researchers, scientists, and policymakers to get in-depth and systematic knowledge on microgrid. It will also contribute to identify the key factors for mobilizing this sector for a sustainable future.
•A brief overview of microgrids and its basics are presented.•An in-depth review on microgrids classification is included.•Mathematical modeling is vigorously explained with a simulation case study.•Challenges associated with microgrid implementation are thoroughly analyzed.•Future research areas worth exploring for microgrids are also outlined.
This study aims to review the potential benefits of peak load shaving in a microgrid system. The relevance of peak shaving for a microgrid system is presented in this research review at the outset to ...justify the peak load shaving efficacy. The prospective benefits of peak shaving in microgrid systems, including technological, economic, and environmental advantages, are thoroughly examined. This review study also presents a cost–benefit numerical analysis to illustrate the economic viability of peak load shaving for a microgrid system. Different peak shaving approaches are briefly discussed, as well as the obstacles of putting them into practice. Finally, this review study reveals some potential future trends and possible directions for peak shaving research in microgrid systems. This review paper lays a strong foundation for identifying the potential benefits of peak shaving in microgrid systems and establishing suitable projects for practical effectuation.
Peak load reduction is one of the most essential obligations and cost-effective tasks for electrical energy consumers. An isolated microgrid (IMG) system is an independent limited capacity power ...system where the peak shaving application can perform a vital role in the economic operation. This paper presents a comparative analysis of a categorical variable decision tree algorithm (CVDTA) with the most common peak shaving technique, namely, the general capacity addition technique, to evaluate the peak shaving performance for an IMG system. The CVDTA algorithm deals with the hybrid photovoltaic (PV)—battery energy storage system (BESS) to provide the peak shaving service where the capacity addition technique uses a peaking generator to minimize the peak demand. An actual IMG system model is developed in MATLAB/Simulink software to analyze the peak shaving performance. The model consists of four major components such as, PV, BESS, variable load, and gas turbine generator (GTG) dispatch models for the proposed algorithm, where the BESS and PV models are not applicable for the capacity addition technique. Actual variable load data and PV generation data are considered to conduct the simulation case studies which are collected from a real IMG system. The simulation result exhibits the effectiveness of the CVDTA algorithm which can minimize the peak demand better than the capacity addition technique. By ensuring the peak shaving operation and handling the economic generation dispatch, the CVDTA algorithm can ensure more energy savings, fewer system losses, less operation and maintenance (O&M) cost, etc., where the general capacity addition technique is limited.
Energy distribution technique is an essential obligation of an intelligent household system to assure optimal and economical operation. This paper considers a small-scale household system detached ...from the power grids consisting of some electrical components in day-to-day life. Optimal power distribution generated from a photovoltaic system is vital for ensuring economic and uninterrupted power flow. This paper presents an optimal energy distribution technique for a small-scale smart household system to ensure uninterrupted and economical operation. A photovoltaic (PV) system is considered as the primary generation system, and a battery energy storage system (BESS) is viewed as a backup power supply source. The actual load and PV generation data are used to validate the proposed technique collected from the test household system. Two different load profiles and photovoltaic power generation scenarios, namely summer and winter scenarios, are considered for case studies in this research. An actual test household system is designed in MATLAB/Simulink software for analyzing the proposed technique. The result reveals the effectiveness of the proposed technique, which can distribute the generated power and utilize the BESS unit to ensure the optimal operation. An economic analysis is conducted for the household system to determine the economic feasibility. The capital investment of the system can be returned within around 5.67 years, and the net profit of the system is 2.53 times more than the total capital investment of the system. The proposed technique can ensure economical operation, reducing the overall operating cost and ensuring an environment-friendly power system. The developed strategy can be implemented in a small-scale detached interconnected smart household system for practical operation to distribute the generated energy optimally and economically.
The production of maximum wind energy requires controlling various parts of medium to large-scale wind turbines (WTs). This paper presents a robust pitch angle control system for the rated wind ...turbine power at a wide range of simulated wind speeds by means of a proportional–integral–derivative (PID) controller. In addition, ant colony optimization (ACO), particle swarm optimization (PSO), and classical Ziegler–Nichols (Z-N) algorithms have been used for tuning the PID controller parameters to obtain within rated stable output power of WTs from fluctuating wind speeds. The proposed system is simulated under fast wind speed variation, and its results are compared with those of the PID-ZN controller and PID-PSO to verify its effeteness. The proposed approach contains several benefits including simple implementation, as well as tolerance of turbine parameters and several nonparametric uncertainties. Robust control of the generator output power with wind-speed variations can also be considered a significant advantage of this strategy. Theoretical analyses, as well as simulation results, indicate that the proposed controller can perform better in a wide range of wind speed compared with the PID-ZN and PID-PSO controllers. The WT model and hybrid controllers (PID-ACO and PID-PSO) have been developed in MATLAB/Simulink with validated controller models. The hybrid PID-ACO controller was found to be the most suitable in comparison to the PID-PSO and conventional PID. The root mean square (RMS) error calculated between the desired power and the WT’s output power with PID-ACO is found to be 0.00036, which is the smallest result among the studied controllers.
In this study, the performance of an islanded gas turbine power generation system in Malaysia was investigated. Considering the low fuel efficiency of the plant during peak and part-load operations, ...an economic analysis was also carried out, over the period of one year (2017). The case study was conducted on the isolated electrical network of the Universiti Teknologi PETRONAS (UTP), which consists of two gas turbine units with a total capacity of 8.4 MW. Simple performance indicators were developed to assess the performance, which can also be applied to other power stations in Malaysia and elsewhere. Meanwhile, the economy of variable load operations was analyzed using the statistical data of generation, fuel consumption, and loads. The study reveals that the capacity factor of the microgrid in the period was between 52.77–63.32%, as compared to the industrial best practice of 80%. The average plant use factor for the period under review was 75.04%, with a minimum of 70.93% and a maximum of 78.61%. The load factor of the microgrid ranged from 56.68–65.47%, as compared to the international best practice of 80%, while the utilization factor was between 44.22–67.655%. This study further reveals that high fuel consumption rates, due to the peak and part-load operations, resulted in a revenue loss of approximately 17,379.793 USD per year. Based on the present performance of the microgrid, suggestions are made for the improvement of the overall performance and profitability of the system. This work can be valuable for microgrid utility research to identify the most economical operating conditions.
In this research, Aloe Vera Gel (AVG) was incorporated into Unsaturated Polyester Resin (UPR) with jute-cotton union fabric to fabricate partially biodegradable composites. These composites were ...fabricated using a hand lay-up technique and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry Analysis (TGA), thermal conductivity measurements, water absorption tests, degradation assessments, cracking tests, and Universal Testing Machine (UTM) analysis. The study found that increasing the percentage of AVG in the composites led to a decrease in thermal conductivity, indicating improved insulation properties. Samples reinforced with AVG showed enhanced resistance to damage from iron nails, with reduced scratching and fiber displacement observed. However, the addition of AVG resulted in decreased thermal, mechanical, and water resistance properties compared to composites without AVG. FTIR analysis demonstrated interactions between AVG and the matrix materials. In degradation tests, composites subjected to an alkali environment (PH = 11.96) showed the highest weight reduction (2.22 %) compared to those without AVG. Similarly, composites buried in soil exhibited greater weight loss (2.38 %) than their counterparts lacking AVG. Overall, the developed composite's reduced heat transfer rate suggests its potential application as an insulating material in environments such as rural poultry housing and the automotive industry.
The impact of diabetes mellitus on the CNS (Central Nervous System) has gained attention only recently. Peripheral neuropathy has been the primary neuroscience focus of diabetes research. Contrary to ...some early impressions, however, the CNS is not spared by diabetes. Chronically, diabetes mellitus affects the CNS in several ways. Diabetes increases stroke risk and damage, overtreatment with insulin or oral agents can permanently damage the brain, and diabetes may increase the prevalence of seizure disorders. Diabetes changes brain transport, blood flow and metabolism, and may produce a chronic encephalopathy. Acutely, glycemic extremes cause coma, seizures, focal neurolclgical deficits, and impaired consciousness. The pathophysiological basis for these marked CNS abnormalities seen in hypoglycemia, hyperosmolar coma, and ketoacidosis are largely unknown.Methods: This review was based on a search of Pubmed, the NCBI Database of systemic Reviews, and citation lists of relevant publications. Subject heading and key words used central nervous system, diabetes mellitus, stroke, encephalopathy and hypoglycaemia. Only articles in English were included.J MEDICINE July 2017; 18 (2) : 109-112
A review on peak load shaving strategies Uddin, Moslem; Romlie, Mohd Fakhizan; Abdullah, Mohd Faris ...
Renewable & sustainable energy reviews,
02/2018, Letnik:
82
Journal Article
Recenzirano
In this study, a significant literature review on peak load shaving strategies has been presented. The impact of three major strategies for peak load shaving, namely demand side management (DSM), ...integration of energy storage system (ESS), and integration of electric vehicle (EV) to the grid has been discussed in detail. Discussion on possible challenges and future research directions for each type of the strategy has also been included in this review. For the energy storage system, different technologies used for peak load shaving purpose, which include their methods of operation and control have been elaborated further. Finally, the sizing of the ESS storage system is discussed. For the demand side management system, various management methods and challenges associated with DSM implementation have been thoroughly explained. A detailed discussion on the electric vehicle strategy has also been included in the review, which considers the integration, control and operation techniques for implementing the peak load shaving.
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