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2009

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Full-Text Articles in Engineering

Design And Implementation Of Dstatcom For Fast Load Compensation Of Unbalanced Loads, Wei-Neng Chang, Kuan-Dih Yeh Dec 2009

Design And Implementation Of Dstatcom For Fast Load Compensation Of Unbalanced Loads, Wei-Neng Chang, Kuan-Dih Yeh

Journal of Marine Science and Technology

This paper proposes a distribution level static synchronous compensator (DSTATCOM) for fast load compensation of unbalanced loads in electric power distribution systems. For fast response requirement, a new feedforward compensation scheme is derived and employed in the paper. First, the compensation scheme of the DSTATCOM is derived with the symmetrical components method. Then, computer simulation with the program Matlab/Simulink preliminarily verifies the effectiveness of the proposed DSTATCOM. Accordingly, a hardware prototype is built with a floating-point DSP TMS320C6711-based system. Use of a current-regulated PWM (CRPWM) inverter as the power stage of the DSTATCOM generates needed compensation currents for real-time load …

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Robust Stability Bounds For Lur'e System With Parametric Uncertainty, Chyun-Chau Fuh, Pi-Cheng Tung Dec 2009

Robust Stability Bounds For Lur'e System With Parametric Uncertainty, Chyun-Chau Fuh, Pi-Cheng Tung

Journal of Marine Science and Technology

The robust stability of Lur’e system with parametric uncertainty is studied through the Popov-Lyapunov approach. Robust stability bounds of such a system are presented. Since we avoid using norm forms and absolute values, the obtained stability bounds are less conservative. An example demonstrating the feasibility of our method is illustrated

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Non-Darcy Flow And Heat Transfer In A Porous Insulation With Infiltration, Hwa-Chong Tien, Kwang-Sheng Chiang Dec 2009

Non-Darcy Flow And Heat Transfer In A Porous Insulation With Infiltration, Hwa-Chong Tien, Kwang-Sheng Chiang

Journal of Marine Science and Technology

This work analyzes non-Darcy flow and heat transfer in a vertical slot filled with a porous matrix. The left and right vertical boundaries of the porous system are maintained at higher and lower temperatures, respectively. The horizontal boundaries are assumed to be impermeable and insulated. The vertical boundaries are either completely impermeable, where free convection is induced, or partially permeable in a way to simulate the wall leakage in the building materials, where both air infiltration and free convection exist. The non-Darcy model, which includes the Brinkman and Forchheimer extensions along with the convection terms, is employed to describe the …

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Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung Dec 2009

Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung

Journal of Marine Science and Technology

A fuzzy gain scheduling proportional controllers that exhibits the improved performance than the conventional linear fixed gain controller having input saturation is proposed in this paper. We proposed an adaptive anti-windup control system in which the gain of a proportional controller is dynamically tuned by a fuzzy PD system. The methodology employed in the analysis is based on the describing function (DF), which is determined the range of the universal discourse for the output of the fuzzy PD system. Other approaches are the linear quadratic regulator (LQR) method and combined back-calculation and generalized conditioning anti-windup. In this paper, a comparison …

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The Construction Common Product Coding System And Auto Id Technology In Construction, Nai-Hsin Pan Dec 2009

The Construction Common Product Coding System And Auto Id Technology In Construction, Nai-Hsin Pan

Journal of Marine Science and Technology

Automatic data identification (Auto ID) technology such as bar code has grown rapidly in various industries. During the last couple of years, a small number of construction companies have also started to implement Auto ID technologies for a limited number of applications. The focus of these applications has primarily been limited to the internal operations of a few larger companies. One of the major barriers to adopt modern Auto ID technologies in the construction industry is the lack of Construction Common Product Code System (CCPCS). The main objective of this research is to investigate the problems created by inadequate CCPCS …

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A Novel Stability Condition And Its Application To Ga-Based Fuzzy Control For Nonlinear Systems With Uncertainty, Po-Chen Chen, Cheng-Wu Chen, Wei-Ling Chiang, Ken Yeh Dec 2009

A Novel Stability Condition And Its Application To Ga-Based Fuzzy Control For Nonlinear Systems With Uncertainty, Po-Chen Chen, Cheng-Wu Chen, Wei-Ling Chiang, Ken Yeh

Journal of Marine Science and Technology

In this study, we strive to combine the advantages of fuzzy logic control (FLC), genetic algorithms (GA), H∞ tracking control schemes, smooth control and adaptive laws to design an adaptive fuzzy sliding model controller for the rapid and efficient stabilization of complex and nonlinear systems. First, we utilize a reference model and a fuzzy model (both involving FLC rules) to describe and well-approximate an uncertain, nonlinear plant. The FLC rules and the consequent parameter are decided on via GA. A boundary-layer function is introduced into these updated laws to cover modeling errors and to guarantee that the state errors converge …

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Service Life Prediction Of Pier For The Existing Reinforced Concete Bridges In Chloride-Laden Environment, Ming-Te Liang, Ran Huang, Shen-An Feng, Chi-Jang Yeh Dec 2009

Service Life Prediction Of Pier For The Existing Reinforced Concete Bridges In Chloride-Laden Environment, Ming-Te Liang, Ran Huang, Shen-An Feng, Chi-Jang Yeh

Journal of Marine Science and Technology

The prediction method of service life for bridge structures is played an important role of bridge management system. In this paper, the mathematical modeling was to study the servise life prediction of pier for existing reinforced concrete (RC) bridge exposed to chloride environment. The corrosion process has three stages, the initiation time (tc), the depassivation time (tp), and the corrosion (propagation) time (tcorr). The total service life of pier for the existing RC bridge can be expressed as t = tc + tp + tcorr. Many mathematical models were applied to predicting each value of the tc, tp, and tcorr. …

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Dsp-Based Implementation Of A Real-Time Doa Estimator For Underwater Acoustic Sources, Sheng-Yun Hou, Shun-Hsyung Chang, Hsien-Sen Hung, Jiang-Yao Chen Dec 2009

Dsp-Based Implementation Of A Real-Time Doa Estimator For Underwater Acoustic Sources, Sheng-Yun Hou, Shun-Hsyung Chang, Hsien-Sen Hung, Jiang-Yao Chen

Journal of Marine Science and Technology

Many direction-of-arrival (DOA) estimation algorithms for acoustic sources based on sensor array measurements have been well developed and verified via computer simulations and/or small-scale water trough experiments. However, these results are not in practical use because the testing scenarios may not reflect real underwater environments. In order to have a better understanding of DOA estimation in sea experiments, a prototype of DSP-based acoustic DOA estimator is designed and implemented. The prototype system is based on TMS320VC33 digital signal processor and is validated by both computer simulation and experiments performed on the shallow water of Bi-Sha fishery harbor located near the …

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Cpt-Based Simplified Liquefaction Assessment By Using Fuzzy-Neural Network, Shuh-Gi Chern, Ching-Yinn Lee Dec 2009

Cpt-Based Simplified Liquefaction Assessment By Using Fuzzy-Neural Network, Shuh-Gi Chern, Ching-Yinn Lee

Journal of Marine Science and Technology

Due to the difficulty and the cost of obtaining high quality undisturbed samples, simplified methods based on in-situ tests such as the standard penetration test (SPT) and the cone penetration test (CPT) are preferred by geotechnical engineers for evaluation of earthquake induced liquefaction potential of soils. Because of the increasing popularity worldwide of the CPT for site characterization, significant progress on the CPTbased methods has been made. In most existing CPT-based methods, empirically determined curves are used to predict liquefaction and non-liquefaction. These empirical curves are generally relied on engineering judgment and are essentially performance functions that were established based …

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Fundamental Properties Of Linear Ship Steering Dynamic Models, Ching-Yaw Tzeng, Ju-Fen Chen Dec 2009

Fundamental Properties Of Linear Ship Steering Dynamic Models, Ching-Yaw Tzeng, Ju-Fen Chen

Journal of Marine Science and Technology

This paper is concerned with the fundamental properties associated with the Nomoto models. Specifically, the state space model associated with the first order Nomoto model is both observable and controllable. The state space model associated with the second order Nomoto model is also observable; however, it is controllable only if the effective sway time constant is different from the effective yaw time constant. The zero appearing in the transfer function model is found responsible for the overshoot behaviors, which are typical in the yaw rate for large rudder angle steering. This suggests that a second order Nomoto model is more …

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Degradation Of The Bond Strength Between Rebar And Concrete Due To The Impressed Cathodic Current, Jiang-Jhy Chang, Weichung Yeih, Ran Huang Dec 2009

Degradation Of The Bond Strength Between Rebar And Concrete Due To The Impressed Cathodic Current, Jiang-Jhy Chang, Weichung Yeih, Ran Huang

Journal of Marine Science and Technology

In this study, the degradation of the bond strength between the steel rebar and concrete by the impressed cathodic current was investigated. Experimental results showed that the bond strength degraded as the charging current density and the polarization time increased basically. A new parameter representing the total transferred electrons per unit protected area was proposed, and the bond strength was found to decrease as the parameter increased after some value.

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A Representation Of Gm-Variation In Waves By The Volterra System, Jianbo Hua, Wei-Hui Wang, Jiang-Ren Chang Dec 2009

A Representation Of Gm-Variation In Waves By The Volterra System, Jianbo Hua, Wei-Hui Wang, Jiang-Ren Chang

Journal of Marine Science and Technology

As known, the variation of the metacentric height of a ship in irregular waves is not a pure linear process, particular when a ship has large beam to draught ratio and large flare near the waterline at bow and stern. This kind of unconventional hull form is usually adopted for modern RoRo-ship, cruise-ship etc. which allows large cargo space and high service speed. In this paper, the GM-variation is derived into a function series with respect to the variation order and represented by the Volterra system. The transfer functions for the different orders are integrated numerically or analytically through expressing …

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Spanning Trees For Binary Directed De Bruijn Networks And Their Applications To Load Balancing, Ming-Bo Lin, Ming-Hong Bai, Gene Eu Jan Dec 2009

Spanning Trees For Binary Directed De Bruijn Networks And Their Applications To Load Balancing, Ming-Bo Lin, Ming-Hong Bai, Gene Eu Jan

Journal of Marine Science and Technology

One of the major reasons of using parallel computer systems is that they have the potential for improving performance and resource sharing. To achieve this, an efficient way must be provided to broadcast a message or messages from a node to every other nodes in the system. However, the efficiency of transferring messages in a system is determined by the architecture of the underlying interconnection network of the system. In this paper, we consider the systems based on binary directed de Bruijn networks and define two shortest path spanning trees: the upward-0 spanning tree and the downward-0 spanning tree, to …

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Minerva 2009, The Honors College Dec 2009

Minerva 2009, The Honors College

Minerva

This issue of Minerva includes a story on alumna Betsy Leitch and her husband Bill Leitch, Betsy's connection to Colvin Hall, and their ongoing support of Honors; an article about Colvin Hall renovations and the opening of the Margaret Chase Smith Visiting Faculty Suite; and an interview with Pulitzer Prize-winning Honors graduate, Bettina Boxall. Other highlights include the story of Honors graduate Adam Jones and his involvement in saving the USS Alabama.

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Spatial Instability Of Electrically Driven Jets With Finite Conductivity And Under Constant Or Variable Applied Field, Saulo Orizaga, Daniel N. Riahi Dec 2009

Spatial Instability Of Electrically Driven Jets With Finite Conductivity And Under Constant Or Variable Applied Field, Saulo Orizaga, Daniel N. Riahi

Applications and Applied Mathematics: An International Journal (AAM)

We investigate the problem of spatial instability of electrically driven viscous jets with finite electrical conductivity and in the presence of either a constant or a variable applied electric field. A mathematical model, which is developed and used for the spatially growing disturbances in electrically driven jet flows, leads to a lengthy equation for the unknown growth rate and frequency of the disturbances. This equation is solved numerically using Newton’s method. For neutral temporal stability boundary, we find, in particular, two new spatial modes of instability under certain conditions. One of these modes is enhanced by the strength Ω of …

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Bs News Dec 2009

Bs News

Building Services Engineering

No abstract provided.

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Ziegler-Natta Catalyst With High Activity And Good Hydrogen Response, L Sinthusai, W Trakarnpruk, R Strauss Dec 2009

Ziegler-Natta Catalyst With High Activity And Good Hydrogen Response, L Sinthusai, W Trakarnpruk, R Strauss

Journal of Metals, Materials and Minerals

Ziegler-Natta catalysts were prepared from chemical reaction route comprising of steps of 1) magnesium complex formation between butyloctyl magnesium and 2-ethyl-1-hexanol, 2) MgCl2 support preparation from the reaction between the magnesium complex and TiCl4 as chlorinating agent and 3) titanation with TiCl4. The catalysts were used for ethylene polymerization using triethylaluminum as a cocatalyst. Effects influencing properties of catalysts and polymerization performance were investigated: triethylaluminum/Mg molar ratio, Ti/Mg molar ratio, addition of electron donor and aging step. Results show that addition of ethylbenzoate as an electron donor resulted in decreased catalytic activity. However it was found that catalytic stability under …

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Preparation And Characterization Of Silicon From Rice Hulls, E Swatsitang, M Krochai Dec 2009

Preparation And Characterization Of Silicon From Rice Hulls, E Swatsitang, M Krochai

Journal of Metals, Materials and Minerals

High purity silica can be prepared by reflux raw rice hulls in 1 N HCl for 45 minutes first, then pyrolyzed at 650°C for 3 hours in O2 atmosphere. The obtained white ash was examined by XRD showing a broad peak of amorphous silica at 2 theta = 22 degree. Silicon can be prepared by metallothermal reduction of pure silica at 650°C in Ar atmosphere for 1-3 hours, using magnesium (99% purity) as a reducing agent. High purity silicon (99.98 %) can be obtained by subsequently washing the as-reduced silica with HCl: H2O and HF: H2O solutions. The results from …

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A Simple Method For Production Of Humidity Indicating Silica Gel From Rice Husk Ash, J Nayak, J Bera Dec 2009

A Simple Method For Production Of Humidity Indicating Silica Gel From Rice Husk Ash, J Nayak, J Bera

Journal of Metals, Materials and Minerals

The objective of the present work is to develop a procedure for obtaining and characterizing active blue silica from rice husk ash. About 25 wt.% silica powder (from total mass of rice husk) of 95% pure silica could be produced after heat-treating at 700°C for 6 hours. A simple method based on alkaline extraction followed by acid precipitation was developed to produce pure silica hydrogel from RHA. A well-defined very minimum amount CoCl2-containing blue silica gel was prepared by impregnation of the aqueous solution of the salt to silica hydrogel, ageing and drying method. The sharp colour changing from blue …

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Synthesis And Characterization Of Sio2 Nanowires Prepared From Rice Husk Ash, S Pukird, P Chamninok, S Samran, P Kasian, K Noipa, L Chow Dec 2009

Synthesis And Characterization Of Sio2 Nanowires Prepared From Rice Husk Ash, S Pukird, P Chamninok, S Samran, P Kasian, K Noipa, L Chow

Journal of Metals, Materials and Minerals

SiO2 nanowires were synthesized by thermal evaporation of rice husk ash and coconut shell charcoal with the ratio of 1:2 by weight heated at a temperature of 1,350ο C in atmosphere of nitrogen for 1 hour. The scanning electron microscope and X-rays diffraction instrument are used to characterize the SiO2 nanowires. The SiO2 nanowires synthesized have diameters varying from 40 nm to 200 nm while the lengths were a few micrometers.

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Pozzolanic Activity Of Rice Husk Ash: Comparison Of Various Electrical Methods, S Wansom, S Janjaturaphan, S Sinthupinyo Dec 2009

Pozzolanic Activity Of Rice Husk Ash: Comparison Of Various Electrical Methods, S Wansom, S Janjaturaphan, S Sinthupinyo

Journal of Metals, Materials and Minerals

The great abundance of rice husk ash (RHA) as low-cost agricultural waste in Thailand makes it the most suitable material for cement-based applications. However, the use of RHA as a supplementary cementitious material (SCM) is not yet widespread in Thailand due to the poor pozzolanic activity of most agricultural RHA. Most RHA is incinerated at too high temperatures (usually in excess of 1000ºC) or under uncontrolled conditions as biomass fuel. This reduces the amount of amorphous SiO2 and hence worsens the pozzolanic activity of the resulting RHA. To enhance the use of RHA as an SCM in Thailand, a proper …

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Exergetic And Thermoeconomic Analyses Of The Rice-Husk Power Plant In Thailand, P Peerapong, B Limmeechokchai Dec 2009

Exergetic And Thermoeconomic Analyses Of The Rice-Husk Power Plant In Thailand, P Peerapong, B Limmeechokchai

Journal of Metals, Materials and Minerals

The purpose of this study is to analyze a rice husk power plant, and consider the efficiency of the power plant through both the first law and the second law of thermodynamics. The energetic and exergetic performance criteria such as thermal efficiency, exergy efficiency, and exergy loss have been found to be useful methods in design, evaluation, optimization and improvement of thermal power plants. The exergetic efficiency of a power plant shows that the boiler is the major component contributing to total loss, with its exergetic efficiency of 30%, while the steam turbine has the exergetic efficiency of 76%. The …

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Synthesis And Characterization Of Silicon-Silicon Carbide Composites From Rice Husk Ash Via Self-Propagating High Temperature Synthesis, S Niyomwas Dec 2009

Synthesis And Characterization Of Silicon-Silicon Carbide Composites From Rice Husk Ash Via Self-Propagating High Temperature Synthesis, S Niyomwas

Journal of Metals, Materials and Minerals

Silicon-Silicon Carbide (Si-SiC) composites were synthesized by self-propagating high temperature synthesis (SHS) from a powder mixture of rice husk ash (RHA)-C-Mg. The reaction was carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The comparison of silica from RHA and commercial sources in the precursor mixture on the Si-SiC conversion has investigated using X-ray diffraction and scanning electron microscope technique. The as-synthesized products of Si-SiC-MgO powders were leached with 0.1M HCl acid solution to obtain the …

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Utilization Of Rice Husk To Synthesize High-Performance Phosphors, L Xiong, K Saito, S Wada, E H. Sekiya Dec 2009

Utilization Of Rice Husk To Synthesize High-Performance Phosphors, L Xiong, K Saito, S Wada, E H. Sekiya

Journal of Metals, Materials and Minerals

Rice husk (RH) has high C and Si contents, so it can be used not only as a fuel candidate, but also as a low-cost Si source for synthesizing high-performance products. In the present work, we proposed a low-cost route to synthesize high-performance silicate phosphors with RH. RH was burned either as received or as pretreated by HCl washing. The resulting ashes were, respectively, utilized to react with other raw materials at high temperatures to form silicate phosphors. The high-temperature solid-state reaction process was optimized by varying either the temperature or the holding time. The crystallographic and fluorescent properties of …

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Preparation Of Silica Gel From Rice Husk Ash Using Microwave Heating, S Rungrodnimitchai, W Phokhanusai, N Sungkhaho Dec 2009

Preparation Of Silica Gel From Rice Husk Ash Using Microwave Heating, S Rungrodnimitchai, W Phokhanusai, N Sungkhaho

Journal of Metals, Materials and Minerals

The purpose of this research is to separate silica gel from rice husk ash by microwave heating. The experiments were performed by heating rice husk ash in sodium hydroxide solution with various concentrations in microwave oven for 5 or 10 minutes. The obtained sodium silicate was neutralized to give silica gel. The best condition for silica gel production was the reaction with 2.0 M sodium hydroxide at microwave power of 800 W for 10 minutes. The ability of silica gel as desiccant was investigated by adsorption test. The results showed that silica gel prepared by low concentration of sodium hydroxide …

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Utilization Of Silica In Rice Hulls As Raw Materials For Silicon Semiconductors, T Okutani Dec 2009

Utilization Of Silica In Rice Hulls As Raw Materials For Silicon Semiconductors, T Okutani

Journal of Metals, Materials and Minerals

Highly pure silicon and silicon compounds are required in high technology products such as semiconductors and solar cells. Rice hulls consist of 71 to 87wt% organic components such as cellulose and 13 to 29wt% inorganic components. In rice hulls, 87 to 97wt% of the inorganic components are silica (SiO2). Rice plants absorb water-soluble siliceous ions via the roots. These ions are transported to stems, leaves and rice hulls by sap flow. In rice hulls, siliceous ions accumulate at the cuticle outside of the epidermis. The production of pure silicon compound (SiCl4) and of silicon metal as the starting material for …

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Utilization Of Rice Husk Ash Silica In Controlled Releasing Application, P Prawingwong, C Chaiya, P Reubroycharoen, C Samart Dec 2009

Utilization Of Rice Husk Ash Silica In Controlled Releasing Application, P Prawingwong, C Chaiya, P Reubroycharoen, C Samart

Journal of Metals, Materials and Minerals

Mesoporous silica was produced by sol-gel technique using rice husk ash as a silica source which was applied in the drug delivery system. The drug releasing behavior was studied in phosphate buffer using indigo carmine as a drug model. The textural properties of mesoporous silica were characterized and considered with the result of the releasing study. The pore volume and silanol group on the surface of mesoporous silica affected the releasing behavior. The larger pore volume could contain the larger amount of drug which showed fast release. The effect of the silanol group presented an interaction between the drug molecule …

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Crystal Habit Of Caco3 Under Different Carbonation Methods, J Ariyaprayoon, U Leela-Adisorn, A Supsakulchai Dec 2009

Crystal Habit Of Caco3 Under Different Carbonation Methods, J Ariyaprayoon, U Leela-Adisorn, A Supsakulchai

Journal of Metals, Materials and Minerals

The saturated solutions of Ca(OH)2 were carbonated by CO2 in air under static and turbulent conditions. The saturation state of starting solution and carbonation methods had effect on the crystal habit. The phase of CaCO3 precipitated from saturated solution is calcite. No metastable phase of CaCO3 was found.

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Influence Of Impurity Ions On Rice Husk Combustion, L Xiong, K Saito, E H. Sekiya, P Sujaridworakun, S Wada Dec 2009

Influence Of Impurity Ions On Rice Husk Combustion, L Xiong, K Saito, E H. Sekiya, P Sujaridworakun, S Wada

Journal of Metals, Materials and Minerals

Rice husk (RH) contains various impurity ions such as K+ , Al3+, Fe3+, Mnn+ (n = 2 - 4), and P-containing acid ions. In the present work, some of their oxides, formed in RH combustion, were found to exert a strong influence on the middle- and late stages of RH combustion, and consequently, strongly affected the structure and properties of the final ash. Very recently, we proved for the first time that the existence of the transition metallic ions in rice husk can lead to a decrease of about 70°C in the terminal combustion temperature (Ttc) of RH. This catalytic …

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Effect Of Black Rice Husk Ash Substituted Opc On Strength And Leaching Of Solidified Plating Sludge, R Piyaphanuwat, S Asavapisit Dec 2009

Effect Of Black Rice Husk Ash Substituted Opc On Strength And Leaching Of Solidified Plating Sludge, R Piyaphanuwat, S Asavapisit

Journal of Metals, Materials and Minerals

Strength and leachability of the solidified plating sludge using OPC and BHA as solidification binders were investigated. BHA was used to replace OPC at 0, 20 and 30 wt.%, and was used to solidify 30 and 50 wt.% of the plating sludge. Results showed that no strength was observed during the first 7 days of curing when OPC was used to solidify the plating sludge. But when 20 and 30 wt.% of BHA were used to substitute OPC, the solidified wastes containing 50 wt.% of the plating sludge gave strength of 4.5 kg/cm2 at the age of 3 and 4.1 …

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