Advanced Materials Research Vols. 291-294

Abstract: Reconstruction of high temperature melting compound steel slag-fly ash can be effectively digest f-CaO in steel slag. The experimental result shows that the f-CaO contents in modified slag is greatly affected by fly ash addition(respectively 5%, 7%, 14%) when the temperature is 1580°C and constant temperature is 30min, the digestion rates are respectively 56.99%,63.69%,68.55%. Modified mineral content of the steel slag changes greatly, mainly reflects at enormous increase in magnetite, dicalcium silicate, tricalcium silicate, wustite and vitreous. By micro-structure analysis of several kinds of modified slag mineral, tricalcium silicate mainly shape for branch of tree, dicalcium silicate is in the form of a circular, wustite and vitreous mainly distribute in aggregation state. The above minerals can increase cementitious activity for modified slag becoming cement.

Abstract: In order to make the resistance underwater as small as possible, the shape of cavitator has been studied, and supercavitation resistance and drag reduction which related to the foreign experimental results is discussed. In this paper, first the super-cavity underwater body shape is optimized. we analyzed the super-cavity flow model and has gain cavity's radius function in the optimization, then use the path of least resistance, which result in Mathematical modeling with the largest cavity volume by the double goals of optimizing, and the constraints are given.

Abstract: Based on thermodynamic principles, the coupled systems performance of the Rankine cycle and the transcritical CO₂ compression cycles with a throttle valve and the cycle with an expander were analyzed, respectively. The results show that the corresponding maximum performance in transcritical CO₂ heat pump, there is an optimal efficiency of the coupled system. With the temperature increasing of boiler feed water, the efficiency of the two coupled system showed an increasing trend; with increasing of discharge pressure of condenser or outlet temperature of gas cooler, both of the two kinds coupled system efficiency showed a downward trend. Under the same conditions, the efficiency of the coupled system with an expander is better than the system with a throttle valve. This paper can provide the fundamental datum for the power plant waste heat recovery.

Abstract: In this paper, Cost-effectiveness of various straw pulp wastewater treatment technologies were compared in detail, moreover the separate and combined process of Coagulation Sedimentation, Anaerobic Baffled Reactor, Sequencing Batch Reactor and Biological Aerated Filter processes were researched. The test result has showed that when addition dosage of PAM and PAC is 4mg/L and 80mg/L in Coagulation Sedimentation separately, and ABR HRT is 10h, the biodegradability of the straw wastewater increased from 0.25 after pretreatment to about 0.45. As the best SBR HRT is 8h, the COD_cr removal rate was about 62%, the BOD₅ removal rate was 70.7% averagely, and the treatment effectiveness is steady correspondingly. But in combined process, the COD_cr removal rate of SBR unit is significantly increased to 78%, the COD_cr removal rate of whole system is higher than 90%. Finally, the BAF has been applied to the advanced treatment on outwater of two biological treatment. The experimental results show that there is a good efficiency on the advanced treatment of the using the method, the COD_cr of outwater is 78 mg/L, the BOD₅ is 28 mg/L, the chroma is 32 times, the SS is 38 mg/L, and the treated water not only meets the state's new discharge standards (GB3544-2008), but also satisfies the requirements of reuse water, and the cost of whole treatment is only RMB 1.80 yuan / m³ wastewater.

Abstract: Solidification tests of MSWI fly ash (FA) with three types of cement including ordinary Portland cements (OPC), calcium sulfoaluminate cement(CSA) and calcium aluminate cement (CAC) were carried out to discuss the effect of cement type on of the FA-cement solid matrix by means of setting time, compressive strength and heavy metals leachability. Results show that the setting time of the FA-cement mixtures using CSA and CAC is shorter than that of OPC. According to compressive strengths demand and the standard of landfill site of municipal solid waste, the dosage of OPC should be limited about 35% by weigh, the dosage of CAC should be limited about 25% by weigh, and the dosage of CSA should be limited more than 40% by weigh.

Abstract: Thermogravimetric behavior of sodium alginate with incorporation of zeolite 4A has been studied. The experiments were performed at air flow rate of 30 ml/min, under heating rates of 5 ~ 30 K/min and up to 1250 K. Kinetic parameters for the main degradation phase thus were estimated by using the pseudo first-order assumption. The results have shown that the introduced zeolite as well as its content has obviously affected thermal properties of sodium alginate.

Abstract: Parameters optimization design of high-speed moving object is a very complex question. It involves many other subjects both in theoretical research and engineering application. Therefore, it is very significant to research on motion parameter optimization design of high-speed moving object. Firstly, in the known initial moment, the entering depth of moving object is; the initial velocity is; the length of moving object is L; the angle into the water is; and the average relative density of object is. It researches on the optimization of the best slenderness ratio, cavitation number and cavitator radius of high-speed objects. And then it specifically deduces the best motion displacement under the known initial momentum. Finally, it takes computer simulation and imitation to all optimized parameters and gives specific numerical examples by applying MATLAB, which provides theoretical basis for actual experiments.

Abstract: The demolished concretes have ever been considered as homogeneous materials and simply crushed to produce recycled aggregates which can only be used for low strength concretes. In mechanical processes of intergrinding in combination with pre-crushing, the sieve residue in each size fraction varies with grinding time and residue-grinding time curves of most fractions have their inflection points that can be considered as termination of separation. The original state aggregates (OSA) so recycled are up to standard of grade II original coarse aggregates specified in China’s standard Pebble and Crushed Stone for Building (GB/T 14685-2001) and can be applied in moderate strength concretes with a bit higher strength than that of original concretes from which the OSA derived. In this method, the OSA can be separated furthest from cement pastes and mortars while suffering minimum damage in separation processes and can retain higher strength.

Abstract: The influence of operational variables in the Sulfonated Chemi-mechanical pulp (SCMP) of cotton stalk was studied, and the hydrogen peroxide bleaching sequence was carried out. The major factors, such as sulfite sodium charge (calculated as Na₂SO₃ 3%, 6%, 9%or 12%on oven-dry cotton stalk), active alkali charge (calculated as NaOH 2%, 4%, 6%or 8%on oven-dry cotton stalk) and the maximum temperature (110°C, 130°C or 150°C) was investigated. The result shows that: the pulp physical property was influenced significantly by sulfite sodium and active alkali charge, at an increasing tendency with above factors. The optimal chemical treatment cooking conditions could be proposed as follows: sulfite sodium charge 9%, active alkali charge 2%, maximum temperature 130°C and liquor ratio 4:1. What’s more, the single H₂O₂ bleaching sequence was employed, which can provide pulps with brightness 58.0%ISO.

Abstract: The present study establishes the relationships between the cutting conditions (cutting speed and feed rate) on trbological properties. Three types of PEEK composites such as unreinforced PEEK, reinforced PEEK with 20% of carbon fibres and 20% of glass fibres were used for the tribological tests. The parametric analysis reveals that, wear increases with increase in feed rate and cutting velocity while the friction coefficient decreases for all the materials tested. The investigation illustrates that the addition of reinforcements to PEEK improve the tribological properties relation with the cutting conditions.