204 research outputs found

    Determine the source term of a two-dimensional heat equation

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    Let Ω\Omega be a two-dimensional heat conduction body. We consider the problem of determining the heat source F(x,t)=φ(t)f(x,y)F(x,t)=\varphi(t)f(x,y) with φ\varphi be given inexactly and ff be unknown. The problem is nonlinear and ill-posed. By a specific form of Fourier transforms, we shall show that the heat source is determined uniquely by the minimum boundary condition and the temperature distribution in Ω\Omega at the initial time t=0t=0 and at the final time t=1t=1. Using the methods of Tikhonov's regularization and truncated integration, we construct the regularized solutions. Numerical part is given.Comment: 18 page

    Implied Volatility Futures Trading Activity and Impacts on Asian Stock Market: An Empirical study

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    This study analyzes impacts of the adoption of a new type of derivatives instrument in the Asian stock market- the implied volatility futures. Furthermore, the analysis is carried on to the preferences of hedging tools in the two pioneering markets in such adoption, Hong Kong and Japan. Unlike other conventional derivatives, the relationship derivatives on volatility and its underlying assets is almost impossible to be modeled, thus creates several difficulties in pricing as well as researching. This paper however is not focused on the complex aspect of modeling such derivatives but more to the event of the introducing of the trading activity. In particular, this will be at first an event study the issue of futures based on the NIKKEI 225 VI Index in Japan and VHSI Index in Hong Kong which are the Asian version of the famous Chicago Board Options Exchange’s VIX Index. Besides, it will also show a causal analysis of those futures contracts and their underlying Indexes. Therefore, the study will give a more insightful about the relationship between futures trading, structural flow of information and volatility in Asian market

    Determination of the body force of a two-dimensional isotropic elastic body

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    Let Ω\Omega represent a two-dimensional isotropic elastic body. We consider the problem of determining the body force FF whose form ϕ(t)(f1(x),f2(x))\phi(t)(f_1(x),f_2(x)) with ϕ\phi be given inexactly. The problem is nonlinear and ill-posed. Using the Fourier transform, the methods of Tikhonov's regularization and truncated integration, we construct a regularized solution from the data given inexactly and derive the explicitly error estimate. Numerical part is givenComment: 23 page

    A nutrient method for cutivation of macroalgae Ulva papenfussii

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    Macroalgae species of the genus Ulva are widely distributed in the wild. Many species of this genus has been used as food as an attractive material for the study of materials, fuels, food etc.. In this paper, we are focusing on nutrient method for cultivation of Ulva papenfussii and A nutrient source for cultivation of U. papenfussii was also investigated with the perspective of utilizing the produced biomass for feed. U. papenfussii is fragmented into 1 × 1 cm size, then it keep in Ulva extract of 0.1 g/l concentrate for 7 days. Then continue to keep fragments in the following conditions: 20 ml/l of PES medium, 700 μmol photon/m2/s of light, 25oC of temperature, 3% of salinity, 28 days of time. Under this condition the productivity U. papenfussii was 17.8 g/l of weight and its growth rate was 4.3–6.5% day. Nutritional cultivation is successful for U. papenfussii speceies, which is of great importance to study the potential of producing seaweed varieties like blades for commercial application of seaweed species.

    Adaptation options for agricultural cultivation systems in the South Central Coast under the context of climate change: Assessment Report.

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    This report highlights the results of consultation meetings and field visits organized by the Department of Crop Production and the CGIAR Research Program on Climate Change, Agriculture and Food Security in Southeast Asia in association with the three offices of the Department of Agriculture and Rural Development in the South Central Coast provinces of Binh Thuan, Ninh Thuan, and Khanh Hoa, in combination with consultation with the provinces in the conference: “Summing up crops production in the Winter-Spring season in 2018-2019, implementing the Summer-Autumn season, Main rice season in 2019 for the South Central Coast and the Central Highlands” held by the Ministry of Agriculture and Rural Development in Tam Ky City, Quang Nam Province on 12 April 2019. The meetings underlined the progress made by the provinces on climate change adaptation and mitigation, options for risk reductions in agricultural production, and conversion of crop structure as results of implementing the guidelines of the provinces and the Sector, especially, solutions for reservation and efficient and economic use of water under the context of climate change. This assessment report also reviews some issues related to the agricultural transformation of the region in adapting to risks caused by climate change. They are based on comparative advantages in terms of geographical location and market of key agricultural products. This report also points out shortcomings in using land and unreasonable points in managing and using important natural resources, especially water, and provides recommendations for the agricultural transformation and inter-regional connection with the Central Highlands and the Southeast. The team also introduces climate-related risks maps and adaptation plans (CS MAP) which is applied in the five provinces in the Mekong Delta Region, and hopes this solution’s expansion shall be supported by the Ministry of Agriculture and Rural Development and the provinces

    Investigation of the thermal properties of different grades Polyamide 12 (PA12) in improving laser sintering process (SLS)

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    Selective Laser Sintering (SLS) is a combined technology of computer and laser to produce complex 3D prototypes directly from CAD modeling. One of the main advantages of employing this technology is that the non-sintered powder can be recycled and reused for another fabrication. However, the fabricated part could be affected by rough and unacceptable surface texture. As a result, the parts may have to be scrapped and the build has to be repeated with a higher ratio of new material. This paper presents an experimental study of the thermal properties of new and recycled of PA12 powder in the Laser Sintering process. The influence of melting temperature, glass transition temperature and crystallization temperature on these properties is investigated. The experimental results have shown that PA12 powder with high melt flow rate, low melting temperature, low glass transition temperature and low degree of crystallization temperature could improve the sintering process
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