Minimize electricity generation cost for large scale wind- thermal systems considering prohibited operating zone and power reserve constraints

Wind power plants (WPs) play a very important role in the power systems because thermal power plants (TPs) suffers from shortcomings of expensive cost and limited fossil fuels. As compared to other renewable energies, WPs are more effective because it can produce electricity all a day from the morning to the evening. Consequently, this paper integrates the optimal power generation of TPs and WPs to absolutely exploit the energy from WPs and reduce the total electricity generation cost of TPs. The target can be reached by employing a proposed method, called one evaluation-based cuckoo search algorithm (OEB-CSA), which is developed from cuckoo search algorithm (CSA). In addition, conventional particle swarm optimization (PSO) is also implemented for comparison. Two test systems with thirty TPs considering prohibited working zone and power reserve constraints are employed. The first system has one wind power plant (WP) while the second one has two WPs. The result comparisons indicate that OEB-CSA can be the best method for the combined systems with WPs and TPs

Optimal generation for wind-thermal power plant systems with multiple fuel sources

In this paper, the combined wind and thermal power plant systems are operated optimally to reduce the total fossil fuel cost (TFFC) of all thermal power plants and supply enough power energy to loads. The objective of reducing TFFC is implemented by using antlion algorithm (ALA), particle swarm optimization (PSO) and Cuckoo search algorithm (CSA). The best method is then determined based on the obtained TFFC from the three methods as dealing with two study cases. Two systems with eleven units including one wind power plant (WPP) and ten thermal power plants are optimally operated. The two systems have the same characteristic of MFSs but the valve loading effects (VLEs) on thermal power plants are only considered in the second system. The comparisons of TFFC from the two systems indicate that CSA is more powerful than ALA and PSO. Furthermore, CSA is also superior to the two methods in terms of faster search process. Consequently, CSA is a powerful method for the problem of optimal generation for wind-thermal power plant systems with consideration of MFSs from thermal power plants

Optimal power generation for wind-hydro-thermal system using meta-heuristic algorithms

In this paper, Cuckoo search algorithm (CSA) is suggested for determining optimal operation parameters of the combined wind turbine and hydrothermal system (CWHTS) in order to minimize total fuel cost of all operating thermal power plants while all constraints of plants and system are exactly satisfied. In addition to CSA, Particle swarm optimization (PSO), PSO with constriction factor and inertia weight factor (FCIWPSO) and Social Ski-Driver (SSD) are also implemented for comparisons. The CWHTS is optimally scheduled over twenty-four one-hour interval and total cost of producing power energy is employed for comparison. Via numerical results and graphical results, it indicates CSA can reach much better results than other ones in terms of lower total cost, higher success rate and faster search process. Consequently, the conclusion is confirmed that CSA is a very efficient method for the problem of determining optimal operation parameters of CWHTS

STUDY ON FLUORINATION AND HYDROGENATION IN TRANSPARENT CONDUCTING ZINC OXIDE THIN FILMS

Fluorination and hydrogenation are known as two methods for enhancing crystalline structural and electrical properties of ZnO material. The ZnO thin films normally require a low resistivity and a high transmittance for using as high-performance transparent electrodes in optoelectronic applications. In this study, we report successful preparation of fluorinated and hydrogenated ZnO thin films (FZO and HFZO) by using d.c. magnetron sputtering technique. The hydrogenation was carried out by depositing the films in hydrogen plasma atmosphere, while a highly-sintered body of ZnO and ZnF2 compound was employed as a sputtering target for the fluorination. The results show that the strong improvements in carrier concentration, mobility and resistivity of the FZO and HFZO films as compared to the pure ZnO films. The carrier concentration increases to 2x1020 cm-3 which is mainly due to the hydrogenation. The effect combination of the fluorination and the hydrogenation is responsibility for enhancing the mobility up to 43 cm2/Vs. These results give rise to two-order reduction in resistivity, from 0.06 Ohm.cm (ZnO) to 7.5x10-4 Ohm.cm (HFZO), which can be a good choice for thin-film electrode application. In addition, the crystalline structure and optical transmission of the films are also discussed

Vietnam geographical exploitation under the United Nations Convention on the Law of the Sea in 1982 (UNCLOS 1982)

As an active member of the United Nations Convention on the Law of the Sea - UNCLOS, Vietnam has completed 3 Reports on the Limits of the Continental Shelf and has submitted two of them to the Commission on the Limits of the Continental Shelf - CLCS, before the deadline 13-5-2009. Those are: (1) Outer Limits of the Vietnam’s Extended Continental Shelf: North Area (VNM-N); (2) Outer Limits of the Vietnam’s Extended Continental Shelf: Middle Area (VNM-M) and (3) Vietnam - Malaysia Joint Continental Shelf Submission. The VNM-M has not yet been submitted but it was mentioned to the CLCS and will be submitted in the appropriate time.Vietnam’s submissions were highly appreciated by CLCS; although the CLCS has not yet organized a special sub-committee to look at our reports, the secretariat of CLCS has already posted the executive reports of our submissions, with our principle claims on the continental shelf, on the website of the CLCS since May 2009. This paper presents shortly the UNCLOS and its application in Vietnam case

In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

Doped ZnO thin films have attracted much attention in the research community as front-contact transparent conducting electrodes in thin film silicon solar cells. The prerequisite in both low resistivity and high transmittance in visible and near-infrared region for hydrogenated microcrystalline or amorphous/microcrystalline tandem thin film silicon solar cells has promoted further improvements of this material. In this work, we propose the combination of major Ga and minor In impurities codoped in ZnO film (IGZO) to improve the film optoelectronic properties. A wide range of Ga and In contents in sputtering targets was explored to find optimum optical and electrical properties of deposited films. The results show that an appropriate combination of In and Ga atoms in ZnO material, followed by in-air thermal annealing process, can enhance the crystallization, conductivity, and transmittance of IGZO thin films, which can be well used as front-contact electrodes in thin film silicon solar cells

Facile Hydrothermal Synthesis of Ag/Fe₃O₄/Cellulose Nanocomposite as Highly Active Catalyst for 4-Nitrophenol and Organic Dye Reduction

Novel effluent treatment solutions for dangerous organic pollutants are crucial worldwide. In recent years, chemical reduction using noble metal-based nanocatalysts and NaBH4, a reducing agent, has become common practice for eliminating organic contaminants from aquatic environments. We suggest a straightforward approach to synthesizing magnetic cellulose nanocrystals (CNCs) modified with magnetite (Fe3O4) and silver nanoparticles (Ag NPs) as a catalyst for organic contamination removal. Significantly, the CNC surface was decorated with Ag NPs without using any reducing agents or stabilizers. PXRD, FE-SEM, TEM, EDX, VSM, BET, and zeta potential tests characterized the Ag/Fe3O4/CNC nanocomposite. The nanocomposite’s catalytic activity was tested by eliminating 4-nitrophenol (4-NP) and the organic dyes methylene blue (MB) and methyl orange (MO) in an aqueous solution at 25 °C. The Ag/Fe3O4/CNC nanocomposite reduced 4-NP and decolored these hazardous organic dyes in a short time (2 to 5 min) using a tiny amount of catalyst (2.5 mg for 4-NP and 15 mg for MO and MB). The magnetic catalyst was removed and reused three times without losing catalytic activity. This work shows that the Ag/Fe3O4/CNC nanocomposite can chemically reduce harmful pollutants in effluent for environmental applications

Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

In this work, undoped, aluminum-, and gallium-doped ZnO thin films (ZnO-H, AZO-H, and GZO-H, respectively) deposited on soda-lime glass substrates by magnetron sputtering method in a gas mixture of hydrogen and argon are annealed at various temperatures in the range of 200–500°C in air to evaluate the durability of those films under annealing temperature. From photoluminescence spectra, formation of point defects, especially oxygen vacancies, when hydrogen diffuses out of the films at high annealing temperature is exhibited via a significant increase of visible emissions. We find out that carrier concentration and Hall mobility of AZO-H and ZnO-H films dramatically decrease, while those of GZO-H film are still stable as the annealing temperature increased from 200°C to 300°C. We proposed a model for interpreting the thermal durability of GZO-H film that, at an annealing temperature of 300°C, Ga3+ ions located at adjacent Zn sites can push hydrogen atoms, which are broken out of the antibonding sites which are perpendicular to the c-axis (AB┴), into bond center sites paralleled to the c-axis (BC//). The movement of hydrogen from AB┴ to BC// site also gives rise to the durability of electrical properties of GZO-H films at the high annealing temperature

Mechanism of proton transport in water clusters and the effect of electric fields: A DFT study

Proton transport inside metal organics frameworks (MOFs) plays an important role to understand and develop a new type of material for a high conductivity application. One of the possible pathways of this process is via water cluster which is confined inside the MOFs structure. In this work, the mechanism of proton transport is investigated within the Density Functional Theory (DFT) calculations. Different water clusters from dimer to pentamer and octamer, which are equivalent to water structures inside the tetrahedral and cubic cavities of MOF-801, respectively, were systematically considered. The results show that proton transfer inside the pentamer cluster has the lowest barrier around 16 kJ/mol. Moreover, the presence of electric fields has a strong effect on the mechanism and energy profile of the proton transfer in both pentamer and octamer cluster. Our DFT prediction of proton migration energies is supported by experimental data of high conducting MOFs such as MOF-801

Poloxamer additive as luminal surface modification to modulate wettability and bioactivities of small-diameter polyurethane/polycaprolactone electrospun hollow tube for vascular prosthesis applications

In regard of engineering small-diameter vascular graft, a stable surface treatment targeting only the tube lumen toward rapid endothelialization and anti-thrombosis without weakening or deconstructing the prosthesis remains a technical challenge. In this study, a bilayer hollow tube with a hydrophilic inner layer polyurethane/polycaprolactone/Poloxamer (PU/PCL/Poloxamer) was fabricated. Poloxamer 407 was blended with PU/PCL as a one-step surface modification to enhance the hydrophilicity and bioactive properties of the electrospun tube’s luminal surface. Hydrophobic polypropylene glycol backbones anchored poloxamer onto based polymer while hydrophilic side chains migrated to the surface to modify the behaviors of electrospun inner surface. The poloxamer blended surface, interestingly, exhibited complicated attraction and repellent behaviors regulated by the dynamic of PEG chains. Moderate grafting density (2 %–8 %) exhibited high bioactive performance of PEG tails to simultaneously modulate cells' adhesion, elongation and proliferation while restricting platelet adhesion in comparison with PU/PCL and super-hydrophilic PU/PCL/Poloxamer surface. The elevation of poloxamer content in composition resulted in a corresponding increase in both hydrophilicity and tensile strength while maintained the homogenous fibrous structure of electrospun mat. Besides, a hydrophobic outer layer PU/PCL was fabricated to prevent the leakage and permeable transmembrane phenomenon toward the sustain application in vascular engineering