Demand response (DR) is a vital part in smart grid to restore the balance between electricity demand and supply. In this paper, a real-time charging scheme is proposed to coordinate the electric ...vehicle (EV) charging and accommodate DR programs in the parking station. The charging scheduling is formulated as a binary optimization problem because the on-off strategy is leveraged to achieve faster charging speed of EV. Given the computationally expensive nature of exhaustive search in solving the optimal solution of binary optimization problem, a convex relaxation method is developed as an alternative to compute the near-optimal charging schedules. Extensive simulation results show that the proposed work is able to satisfy EV charging demand while accommodating both types of DR programs in the parking station. The proposed work is also able to simultaneously maximize the number of EVs for charging and minimize the monetary expenses.
Heat processing is one of the most efficient strategies used in food industry to improve quality and prolong shelf life. However, conventional processing methods such as microwave heating, burning ...charcoal treatment, boiling, and frying are energy-inefficient and often lead to inferior product quality. Superheated steam (SHS) is an innovative technology that offers many potential benefits to industry and is increasingly used in food industry. Compared to conventional processing methods, SHS holds higher heat transfer coefficients, which can reduce microorganisms on surface of foodstuffs efficiently. Additionally, SHS generates a low oxygen environment, which prevents lipid oxidation and harmful compounds generation. Furthermore, SHS can facilitate development of desired product quality, such as protein denaturation with functional characteristics, proper starch gelatinization, and can also reduce nutrient loss, and improve the physicochemical properties of foodstuffs. The current work provides a comprehensive review of the impact of SHS on the nutritional, physicochemical, and safety properties of various foodstuffs including meat, fruits, and vegetables, cereals, etc. Additionally, it also provides food manufacturers and researchers with basic knowledge and practical techniques for SHS processing of foodstuffs, which may improve the current scope of SHS and transfer current food systems to a healthy and sustainable one.
•A constrained optimization algorithm abbreviated as CMPSOWV is proposed.•Two evolution phases are designed into CMPSOWV to solve different COPs robustly.•Two schemes are embedded into CMPSOWV to ...address the premature convergence issue.•The proposed CMPSOWV outperforms its peers in terms of searching accuracy.
The original particle swarm optimization (PSO) is not able to tackle constrained optimization problems (COPs) due to the absence of constraint handling techniques. Furthermore, most existing PSO variants can only perform well in certain types of optimization problem and tend to suffer with premature convergence due to the limited search operator and directional information used to guide the search process. An improved PSO variant known as the constrained multi-swarm particle swarm optimization without velocity (CMPSOWV) is proposed in this paper to overcome the aforementioned drawbacks. Particularly, a constraint handling technique is first incorporated into CMPSOWV to guide population searching towards the feasible regions of search space before optimizing the objective function within the feasible regions. Two evolution phases known as the current swarm evolution and memory swarm evolution are also introduced to offer the multiple search operators for each CMPSOWV particle, aiming to improve the robustness of algorithm in solving different types of COPs. Finally, two diversity maintenance schemes of multi-swarm technique and probabilistic mutation operator are incorporated to prevent the premature convergence of CMPSOWV. The overall optimization performances of CMPSOWV in solving the CEC 2006 and CEC 2017 benchmark functions and real-world engineering design problems are compared with selected constrained optimization algorithms. Extensive simulation results report that the proposed CMPSOWV has demonstrated the best search accuracy among all compared methods in solving majority of problems.
Differential evolution (DE) is a popular evolutionary algorithm inspired by Darwin’s theory of evolution and has been studied extensively to solve different areas of optimisation and engineering ...applications since its introduction by Storn in 1997. This study aims to review the massive progress of DE in the research community by analysing the 192 articles published on this subject from 1997 to 2021, particularly studies in the past five years. The methodology used to search for relevant DE papers and an overview of the original DE are firstly explained. Recent advances in the modifications proposed to enhance the effectiveness and efficiency of the original DE are reviewed by analysing the strengths and weaknesses of each published work, followed by the potential applications of these DE variants in solving different real-world engineering problems. In contrast to most existing DE review papers, additional analyses are performed in this survey by investigating the impacts of various parameter settings on given DE variants to identify their optimal values required for solving certain problem classes. The qualities of modifications incorporated into selected DE variants are also evaluated by measuring the performance gains achieved in terms of search accuracy and/or efficiency against the original DE. The additional surveys conducted in this study are anticipated to provide more insightful perspectives for both beginners and experts of DE research, enabling their better understanding about current research trends and new motivations to outline appropriate strategic planning for future development works.
The effect of drying temperature (60, 65, 70, and 75 °C) on drying characteristics, shrinkage, rehydration kinetics, microstructure and color profiles of lemon slices were investigated using a ...far-infrared radiation heating assisted pulsed vacuum dryer. Results showed that the drying time of lemon slices was reduced from 10.5 to 5.5 h when the drying temperature was increased from 60 to 75 °C. Weibull model could precisely describe the drying of samples under different drying temperatures (R2 > 0.99). Moisture effective diffusivity (Deff), which was determined by taking shrinkage effect into consideration, varied with moisture content. At the initial drying stages, the volume shrinkage of samples followed a linear relationship with decreasing moisture content as the volume shrinkage is approximately equal to the volume of evaporated water. Microstructure observation illustrated that the “skeleton” was fixed when moisture content decreased to approximate 60% w.b. Page model could well model the rehydration kinetics (R2 > 0.98). In terms of color evaluation, temperature of 75 °C significantly caused color deterioration and it recorded the highest color change (ΔE) of 14.23, Browning Index (BI) of 27.14 and lowest Hue Angle (H0) of 79.46. The findings indicate that FIR-pulsed vacuum drying is a promising alternative method for lemon slices as it can enhance drying process as well as preserve the quality attributes of lemon slices.
•Moisture diffusion was studied by taking shrinkage effect into consideration.•Microstructure observation verified the shrinkage changes of samples under different temperatures.•Page model describes rehydration kinetics well.•Temperature of 75 °C significantly caused color deterioration.
The economic and environmental benefits brought by electric vehicles (EVs) cannot be fully delivered unless these vehicles are fully or partially charged by renewable energy sources (RES) such as ...photovoltaic system (PVS). Nevertheless, the EV charging management problem of a parking station integrated with RES is challenging due to the uncertain nature of local RES generation. This paper aims to address these difficulties by deploying an energy storage system (ESS) in parking stations and exploiting the charging and discharging scheduling of EVs to achieve better utilization of intermittent PVS for EV charging. A real-time charging optimization scheme is also formulated, using mixed-integer linear programming (MILP) to coordinate the charging or discharging power of EVs along with the power dispatches of power grid and ESS based on the vehicles’ charging or discharging priorities and electricity price preferences. Extensive simulations show that the proposed approach not only maximizes the satisfaction of EV owners in terms of fulfilling all charging and discharging requests, but also minimizes the overall operational cost of the parking station by prioritizing the utilization of energy from PVS, ESS, and scheduling of every EV’s charging and discharging.
Demand response (DR) is envisioned as a promising solution to address the demand-supply mismatch issue in electric power systems. A new demand bidding model is considered in this paper to facilitate ...demand response trading in load curtailment form between the aggregator (buyer) and the large contract capacity customers (seller). Different types of customers with different load curtailment characteristics are considered in the demand bidding, leading to the formulation of a nonlinear optimization problem that is computationally expensive to solve. Delicate mechanisms are incorporated into the proposed purchase optimization scheme to reformulate the nonlinear programming problem into an equivalent linear model that can be solved efficiently. Simulation studies show that the proposed work is promising to minimize the total bidding purchase cost while satisfying the given load curtailment constraints that include the load curtailment and the load curtailment patterns of different customers.
Biofuel production by oleaginous microalgae is a promising alternative to the conventional fossil fuels. Many microalgae species have been investigated and deemed as potential renewable sources for ...the production of biofuel, biogas, food supplements and other products. Oleaginous microalgae, named for their ability to produce oil, are reported to store 30–70% of lipid content due to its metabolic properties under nutrient starvation conditions. This review presents the assortment of the research studies focused on biofuel production from oleaginous microalgae. The new methods and technologies developed for oleaginous microalgae cultivation to improve their biomass content and lipid accumulation capacity were reviewed. The production of renewable, carbon neutral, bio-based or microalgae-based transport fuels are necessary for environmental protection and economic sustainability. Microalgae are a significant source of renewable biodiesel because of their ability to produce oils in the presence of sunlight more efficiently than that of crop oils. This review will provide the background to understanding the bottlenecks and the need for improvement in the cultivation or harvesting process for oleaginous microalgae.
Hot air drying of lotus pollen at temperatures ranging from 40 to 70 °C was investigated experimentally. Results indicated that the whole drying process occurred in the falling rate period. Color ...analysis showed that lotus pollen suffered color deterioration. The antioxidant capacity decreased and the fat oxidation activity increased following drying. The carotenoid content exhibited significant loss when dried at 70 °C (p < .05). Zero-order, first-order, and fractional conversion models were employed to fit the experimental data for color profile, antioxidant capacity, and fat oxidation. The first-order fraction model can precisely describe the color change and the antioxidant capacity deterioration, while the kinetics of thiobarbituric acid reactive substances followed the linear model. There is a correlation between color, antioxidant activity, and fat oxidation.
The rapid development of information and wireless communication technologies together with the large increase in the number of end-users have made the radio spectrum more crowded than ever. Besides, ...providing a stable and reliable service is challenging, as electromagnetic environments are evolving and becoming more sophisticated. Accordingly, there is an urgent need for more reliable and intelligent communication systems that can improve the spectrum efficiency and the quality of service to provide agile management of network resources, so as to better meet the needs of future wireless users. Specifically, Automatic Modulation Recognition (AMR) plays an essential role in most intelligent communication systems especially with the emergence of Software Defined Radio (SDR). AMR is an indispensable task while performing spectrum sensing in Cognitive Radio (CR). Thanks to the significant advancements in Deep Learning (DL) applications, new and powerful tools have been provided which can tackle problems in this space. Thus, today, integrating DL models into AMR has gained the attention of many researchers. This work aims to provide a comprehensive state-of-the-art review of the most recent Machine Learning (ML) based AMR methods for Single-Input Single-Output (SISO) and Multiple-Input Multiple-Output (MIMO) systems. Furthermore, the architecture of each model will be identified along with a detailed comparison in terms of specifications and performance. Finally, an outline of the open problems, challenges, and potential research directions is provided along with discussion and conclusion.
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