Regulation of nuclear reactors by duplexed control rods: linearizedanalysis

The dynamic behavior of a duplex control rod for a nuclear reactor is analyzed by linearized modeling. A simulation-aided design for this duplex, which has performance and safety characteristics that are better than those of conventional single control rods with the same stability margins, is reported     

Extraction of zinc from blast‐furnace dust using ammonium sulfate

The reaction between roasted zinc blast‐furnace dust (BFD) and ammonium sulfate was studied in the temperature range 250–450 °C using different molar ratios to determine the maximum extraction of zinc. The reaction products are characterized. The composition of the untreated and roasted BFD, and reaction products was investigated by chemical, thermal, X‐ray diffraction and fluorescence analyses. The decomposition of ammonium sulfate leads to the formation of (NH₄)₂S₂O₇, NH₄HSO₄ and (NH₄)₃H(SO₄)₃. The main zinc reaction products are ZnSO₄, ZnSO₃, (NH₄)₂Zn(SO₄)₂, (NH₄)₂Zn₂(SO₄)₃ and (NH₄)₂Zn₄(SO₄)₅. The reaction mechanisms of these formations are discussed in detail. The identity of these products depends essentially on the temperature as well as the molar ratios of the reactants. The optimum conditions for the formation of soluble zinc compounds are molar ratio 1:8 of roasted zinc dust (ZnO) and (NH₄)₂SO₄ at 350 °C. Under these conditions, up to 95% of zinc was leached with 0.5 M sulfuric acid. Copyright © 2004 Society of Chemical Industry     

Improving the Response of Soil-Metal Structures during Construction

For economic reasons, manufacturers of soil-metal bridges have strived to build these structures under the shallowest possible depth of soil cover, below the one allowed by codes of practice. For such structures, special analysis is needed to circumvent or prevent the formation of failure mechanisms that may be triggered during construction or when subjected to traffic loads. Therefore, special features, such as transverse stiffeners attached to the metal shell and the use of thrust concrete beams, may be required to assist the corrugated metal shell in carrying the loads. In this paper, a novel design is proposed for such structures in which the surrounding soil is reinforced and the metal shell is tied into the soil. A finite-element analysis of long span soil-metal structures with shallow soil cover is carried out using these two designs. The analysis is verified and substantiated using field data obtained during the construction of an 18 m soil-metal bridge. Comparing the structural response from the two designs shows that the latter design can lead to a superior structure.     

Evaluating the potential of plastic-containing materials as alternative reducing agents

The amount of discarded plastic-containing materials is increasing, and one option to help with this issue is to use these materials in bath smelting processes. The injection of plastic-containing materials to partially substitute coal in zinc-fuming processes has been studied in an industrial trial at Boliden–Rönnskär smelter. To evaluate the potential of plastic-containing materials, thermodynamic calculations were performed in this study. In the first step, a thermodynamic calculation was performed for trials with only coal injection, and then this calculation was applied to trials with the co-injection of plastic materials. The thermodynamic calculation shows that not all the injected coal participates in the reactions within the slag. Similarly, the calculation with the co-injection of plastic-containing materials shows that different amounts of each plastic material participate in the reactions within the slag bath.     

Corrosion studies on tailored Zn·Co aluminate/kaolin core-shell pigments in alkyd based paints

Core-shell theory presents a new easy route to obtain high performance, and eco-friendly anticorrosive pigments with concomitant savings. This theory is based on depositing a surface layer of expensive efficient anticorrosive pigment on a cheap extender expressing the bulk. The combination of both core and shell compounds led to the production of new pigments with improved properties different from each of its individual components; and consequently these improved properties lead to change in the efficiency of protection properties of paint films containing these new pigments.The objective of the present work is to prepare a new ecologically friendly inorganic pigment, based on the solid-solid interaction of cobalt oxide with zinc oxide on surface of kaolin. The species of CoO and ZnO are susceptible to react with alumina part in the kaolin forming Zn·Co aluminate/kaolin. The new pigment will be incorporated in medium oil alkyd-based paints. The effect of cobalt aluminate/kaolin, zinc aluminate/kaolin individually and zinc·cobalt aluminate/kaolin on the protection performance of paint films containing them will be compared and studied. Another comparison will be held out between films containing nano- and micro-zinc·cobalt aluminate/kaolin to determine the best among the prepared pigments for better corrosion prevention. The comparison will be done using accelerated laboratory test for 28 days in artificial sea water and electrochemical impedance spectroscopy. The results revealed that nano-pigments and pigments containing higher concentration of zinc were the best in protecting steel substrates.     

Study of the Effect of Natural Rubber-graft-maleic Anhydride (NR-g-MA) on the Compatibility of NR-NBR Blends Using the Ultrasonic Technique

The grafted copolymer of natural rubber (NR) and maleic anhydride (MA) was synthesized in a solution state by using ultraviolet radiation. The NR-g-MA was characterized using infrared (IR) technique. The prepared NR-g-MA was added to a 50/50 blend of NR and acrylonitrile-butadiene copolymer (NBR) as a compatibilizer. The effect of compatibilizer (NR-g-MA) concentrations in the range of 2, 4, 5, 6, 8, and 10 wt.% on the ultrasonic velocity, attenuation coefficient, and ultrasonic viscosity was studied in order to study the compatibility of the 50NR-50NBR blend. Ultrasound pulse echo method was used to measure both the ultrasound velocities and attenuation coefficient at a frequency of 2 MHz. Testing for elastic constant, Poisson's ratio, cross-link density, and microhardness was carried out in different percentages of the blend components to study the degree of the compatibility of the blend. The structure of the blend system was established by differential scanning calorimetry. The addition of NR-g-MA to the blend showed improvement of compatibility in certain concentration ranges and deterioration of compatibility in other ranges.     

节能网络技术争锋有线以太网市场

博通（Broadcom）以IEEEP802．3az节能以太网络（Energy Efficient Ethernet,EEE）草案标准作为其广泛架构的一环,以便在其整个有线以太网络方案中能以最佳成本的低功耗技术来达到高效能的需求。     

Bio-hydrogen production from thin stillage using conventional and acclimatized anaerobic digester sludge

To assess the viability of biohydrogen production from thin stillage, a comparative evaluation of anaerobic digester sludge (ADS) and acclimatized anaerobic digester sludge (AADS) for biohydrogen production over a wide range of S⁰/X⁰ ratio (0.5-8 gCOD/gVSS) was performed. A maximum hydrogen yield of 19.5 L H₂/L thin stillage was achieved for the AADS while tests with ADS achieved a maximum yield of only 7.5 L H₂/L thin stillage. The optimum range of S⁰/X⁰ ratio for hydrogen production was found to be 1 to 2 gCOD/gVSS using conventional ADS and 3 to 6 gCOD/gVSS using AADS. The biomass specific hydrogen production rate for the AADS was 3.5 times higher than rate for the ADS throughout the range of S⁰/X⁰ ratio examined in this study. The DGGE profiles of the 16S rDNA gene fragments confirmed the superior performance of the AADS over the ADS, showing that the widely known hydrogen producers Clostridium acetobutyricum, Klebsiella pneumonia, Clostridium butyricum and Clostridium pasteurianum were the predominant species.     

Air quality and climate change co-benefits for the industrial sector in Durban,South Africa

Industries in Durban, South Africa, are a major source of air pollutant emissions and large users of fossil fuel based energy. Durban’s energy strategy prioritises energy efficiency at industries as a key action, whilst industries are also the focus of the city’s air quality management plan (AQMP). In this paper, measures that have been introduced in industries in Durban to effect air quality improvements and reduce energy consumption are examined in terms of their respective impacts on greenhouse gas (GHG) and air pollutant emissions. It was found that co-benefits for GHG mitigation were achieved when petroleum refineries switched from using heavy fuel oil to refinery gas and methane rich gas. Within other industries, co-benefits for air quality stemmed from reducing fossil fuel energy consumption and the improved efficiency of combustion systems. Air quality and energy policies in the city are being executed independently, without consideration of the trade-offs or synergies of the interventions being implemented. Recommendations are made for authorities and industries to consider the co-benefits for GHG mitigation in their AQMPs and where these are not possible to consider offsetting the increased GHG emissions through improved alignment with energy strategies.