Unit Commitment solution using an optimized genetic system

This paper presents an investigation into the application of an optimized Genetic Algorithm (GA) to solve the Thermal Unit Commitment (UC) problem. A Parallel structure was first developed to handle the infeasibility problem in a structured and improved GA which provides an effective search process and therefore greater economy. The proposed methodology resulted in a better performance with faster operation by using both computational methods and classification of unit characteristics. Typical constraints such as system power balance, minimum up and down times, start-up and shut-down ramps, have also been considered. A number of important parameters (standard and new parameters) of the UC problem have been identified. The proposed method is implemented and tested using a C# program. The tests are carried out using two systems including 10 and 20 units during a scheduling period of 24 h. The results are finally compared with those obtained from genetic schemes in other similar investigations through which the effectiveness of the proposed scheme is affirmed.     

A Brief Assessment of a Dam and Its Failure Prevention

Dams are artificial lakes created to reserve water for a particular purpose. Reports on failure of dams are common things nowadays. Effects of dam’s failure on man and environment are well known, which require preventive measures. This article presents a brief assessment of a dam in Nigeria and suggested necessary failure preventive measures. The dam site was visited (up and down streams), selected soil and geological properties of the dam were conducted with a particular attention to the release of water from the reservoir as seepage, or filling of the reservoir by silt from erosion. Hydrology and hydraulic data of the study area and spillway were obtained and analyzed. The study revealed that the soil is mainly sandy-loamy soil of averagely sand (73.99 ± 3.12), clay (8.53 ± 0.18), and silt (17.48 ± 1.88). Geological structure of the soil revealed that the study area is in basement complex. The reservoir capacity is 177,000,000 m³ with about 18.5-m hydraulic high, silting rate of 0.301% per year. Hydraulic conductivity, transmissivity, and specific discharge were found to be of high side of 9.31 × 10⁻⁴ m/s, 5.08 × 10⁻⁴ m²/s, and 98.25 m/year, respectively. It was concluded that the current problems of the dam are high silting rate and seepage, big trees on the embankment and beside the spillway. All these may lead to failure of the dam in the following ways: lack of water in the reservoir due to seepage and silting, eutrophication and non-potable of the water due to silting and collapse of the embankment due to the presence of big trees. It was suggested that necessary and urgent solutions such as removal of trees from embankment, desilting and seepage control must be provided for safety of lives and properties.     

Antioxidative Properties of <Emphasis Type="Italic">Curcuma longa</Emphasis> Leaf Extract in Accelerated Oxidation and Deep Frying Studies

The antioxidative properties of Curcuma longa (turmeric) leaf extract were evaluated in refined, bleached and deodorized (RBD) palm olein using accelerated oxidation and deep frying studies at 180 °C for up to 40 h. The extract was capable of retarding oil oxidation and deterioration significantly (P < 0.05) at 0.2% concentration, better than 0.02% BHT for the Oxidative Stability Index (OSI) in an accelerated oxidation study and also the peroxide value in deep frying studies. In sensory evaluation, the French fries were acceptable and were not significantly different (P < 0.05) from one another for color, oiliness and crispiness throughout the 40-h frying study. Curcuma longa leaf extract, which had a polyphenol content of 116.3 ± 0.2 mg/g, possessed heat-stable antioxidant properties and may be a good natural alternative to existing synthetic antioxidants in the food industry.     

Synthesis,characterization, and thermal analysis of two polymeric chromium ternary complexes with nitrilotriacetic acid and alanine or glycine

Two chromium ternary complexes with nitrilotriacetic acid as a primary ligand and alanine or glycine as secondary ligand were prepared in slightly acidic medium. The structure of these two complexes was characterized using elemental, thermal analysis, FTIR spectra, and the two complexes mass spectra. The spectroscopy data suggest that these two complexes were in polymeric form and have the monomeric unit H[Cr(HNTA)(Hala)(SO₄)] and H[Cr(HNTA)(Gly)(SO₄)] in which sulfate group act as a bidentate ligand linked between each monomeric unit for the same complex. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Novel CMOS current conveyor realizations suitable for high-frequency applications

Novel CMOS realizations of the second and the third generation current conveyors based on the use of the current conveyor of the first generation are given. The simulations show that these circuits have an excellent performance and an exceptional bandwidth.     

Material screening and choosing methods – A review

The selection of a material for a specific engineering purpose is a lengthy and expensive process. Approximately always more than one material is suitable for an engineering application, and the final selection is a compromise that brings some advantages as well as disadvantages. One of the issues that emerges from this review is that regardless of the relation of design stages and process selection with material selection, screening and ranking are two vital steps in the material selection. A variety of quantitative selection procedures have been developed to solve this issue, so that a systematic evaluation can be made. This paper seeks to address the following questions: (1) what is the contribution of the literature in the field of screening and choosing the materials? (2) What are the methodologies/systems/tools for material selection of engineering components? (3) Which approaches were prevalently applied? (4) Is there any inadequacy of the approaches? This research not only provides evidence that the multi-criteria decision making approaches has the potential to greatly improve the material selection methodology, but also aids the researchers and decision makers in applying the approaches effectively.     

最先进的IC：超声波装置收发器

由于应用物理及电子学的研究及发展，医疗成像领域受益极多．尤其在仪器、影像撷取及建模等方面。由于超声波本身完全无侵人性．因此在各种成像模式中占有特殊地位．为内脏研究提供了可靠的方法。超声波技术用于医疗用途已逾半世纪之久．然而．这类的必要设备不仅体积庞大，而且价格昂贵．直到最近才特别以离散式部件进行制作。     

A numerical and experimental investigation of different containers and PCM options for cold storage modular units for domestic applications

This paper presents the results of an experimental and numerical study on the solidification of different phase change materials (PCM) encapsulated in spherical and cylindrical shells of different materials and diameters subject to constant surface temperature. The main objective is to determine the time for complete solidification of the PCM and how it is affected by the variations of the surface temperature, material and diameter of spherical shells. As a result of the study, it is expected to define a pair of container and PCM to operate adequately and efficiently together with refrigeration units. The experiments were realized using glass and plastic spherical shells of diameters 0.035, 0.076, 0.106 and 0.131 m, soft drink cans and small plastic water bottles with surface temperatures of ?5, ?10, ?12, ?15, ?18, ?20 and ?25 °C. The phase change materials used are water and mixtures of water with 3.75%, 7.5%, 15%, 25%, 30%, 40% and 50% Glycol content. The results are presented and discussed.     

High-Dynamic-Range Wireless-Over-Fiber Link Using Feedforward Linearization

We demonstrate the implementation of feedforward linearization at 5 GHz, which is the highest operating frequency yet reported, with 500-MHz linearization bandwidth having at least 24-dB distortion suppression. Simultaneous reduction of 26-dB third-order intermodulation distortion and 7-dB laser-noise reduction is achieved at 5.2 GHz, leading to enhanced spurious-free dynamic range of 107 dB (1 Hz) in a directly modulated uncooled semiconductor laser for applications in wireless-over-fiber (WoF) systems. This paper also provides detailed analysis on feedforward, theoretical distortion reduction, criteria for component selection, and the effect of dispersion. The effectiveness of feedforward in a multichannel system is demonstrated at 5.8 GHz for fixed wireless systems, such as WiMAX. These results suggest that the feedforward-linearization arrangement can make practical multichannel and multioperator WoF systems.