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Pd is one of the most promising catalysts for carbon dioxide electroreduction (CO2RR) to formate (HCOO-). However, the lack of understanding of the active phase remains remains obscure with the role of different crystal facets in the formation of formic acid. Herein, Pd nanocubes and nanooctahedra particles with Pd (100) and (111) facets were, respectively, prepared. Compared with ordinary Pd nanoparticles and Pd octahedra, Pd nanocubes exhibited the most excellent electrocatalytic performance of carbon dioxide reduction, achieving a Faraday efficiency of 96% for formate production at a low applied potential of-0.20 V (vs RHE) in 0.5 M KHCO3. At the same time, first-principles theoretical calculations also showed that the Pd (100) surface is more conducive to the conversion of CO2 to HCOO* intermediates, thereby promoting the formation of formic acid. This result indicates that the Pd (100) crystal plane is more conducive to the reduction of CO2 to formate. This research has important guiding significance for exploring the efficient reduction of carbon dioxide to formic acid catalyst.

The apparent viscosity and rheological behavior of nanoSiCP/Al-5Cu composites were studied by using a high temperature coaxial rotating cylinder viscometer. The results show that mass fraction of nanoSiCP is an important factor for apparent viscosity of the nanoSiCP/Al-5Cu composites, and there is a great enhancement of apparent viscosity of the slurry with the increase of nanoSiCp content. It can attribute to the viscous force between nanoSiCp and matrix alloy melt above the liquidus. The increased amplitude of apparent viscosity in semi-solid state is far less than those in liquid state with the increase of mass fraction of nanoSiCp. The apparent viscosities of the composites reinforced with 0.5%, 1%, 1.5% and 2% nanoSiCp at 700°C were 24.78%, 95.25%, 160.29% and 228.62% higher than that of Al-5Cu alloy, respectively. Besides, the rheological model of nanoSiCP/Al-5Cu composites was established based on the fitting curve, which can precisely describe the relationship between the apparent viscosity of nanocomposites slurry and nanoSiCp mass fraction.

The influence of high pressure and manganese on Fe-rich phases (FRPs) and mechanical properties of Al-14Si-2Fe alloy with rheo-squeeze casting (RSC) were investigated. The semi-solid alloy melt was prepared using ultrasonic vibration (UV), then formed by squeeze casting (SC). Results shows that the FRPs in as-cast Al-14Si-2Fe-(0.4,0.8)Mn alloys with SC are composed of coarse plate-shaped δ-Al4(Fe,Mn)Si2, long needle-shaped β-Al5(Fe,Mn)Si and bone-shaped α-Al15(Fe,Mn)3Si2phases when the pressure is 0 MPa. During the solidification of the alloys with RSC, the FRPs are first refined by UV, then furtherly refined as the pressure increases. With RSC, the FRPs in Al-14Si-2Fe-0.8Mn alloy are finer and rounder than that of the Al-14Si-2Fe-0.4Mn alloy under the same pressure. The FRPs in RSC Al-14Si-2Fe-0.8Mn alloy are mainly granular particles with an average diameter of about 12 μm under 300 MPa. For the alloy with the same composition, the ultimate tensile strength (UTS) of RSC sample is higher than that of the SC sample. Under the same forming process, the UTS of Al-14Si-2Fe-0.8Mn alloy is higher than that of the Al-14Si-2Fe-0.4Mn alloy.

In this study, the modification effects and mechanism of manganese (Mn) and ultrasonic vibration (USV) on the needle-like Fe-containing intermetallic compounds of Al-20Si-xFe-2.0Cu-0.4Mg-1.0Ni (x=1, 2 wt.%) alloy have been studied respectively. The effect of Fe-containing phases on volume fraction of hard phases is also investigated. The results show that the mechanism and effect of Fe-containing intermetallic compounds improved by Mn are in close relationship with Fe content. Mn can promote to form less harmful α-Al15(Fe,Mn)3Si2 phase, or replace some Fe atoms of β-Al5FeSi and δ-Al4FeSi2 according to different Fe content. When USV was applied to this alloy containing 2%Fe near liquidus temperature, most of the acicular β phases formed in traditional process are substituted by fine plate δ phases. With the combined effects of 0.5%Mn and USV, the acicular β phases are almost repressed and the Fe-containing phases exist in form of fine Al4(Fe,Mn)Si2 and Al5(Fe,Mn)Si particles about 20~30μm. Consequently, the total volume fraction of hard phases which are composed of primary silicon particles and Fe-containing phases increases significantly.

In order to explore the characteristics of fire caused by sodium leakage in sodium-cooled fast reactor loop, an experiment on the sodium fire in form of columnar flow has been conducted. Temperature field characteristics were analyzed by measured results. Near the axis of the combustion container, the high-temperature region of the sodium fire in form of the columnar flow is located in the bottom and the temperatures are all less than 100°C at height from 0.5m to 2.0m under natural ventilation. The temperatures of the space reach the maximum values after forced ventilation and the highest temperature is up to 950°C at height 0.8m above the ground. Once the lateral distance to the sodium flow is more than 0.4m, the temperature field is affected less by the sodium fire in form of columnar flow.

The Fe-rich Al-Si alloys have the potential to be used to make wear-resistant parts. However, there has been few work devoted to study the wear behavior of the hypereutectic Al-Si alloys with about 2% Fe (mass %). In this work, the semi-solid slurry of the alloy was prepared by an ultrasonic vibration (USV) process. The effect of Fe content on dry sliding wear properties of the alloys rheo-casted after USV treatment was investigated. The wear tests were carried out using a pin-on-disc wear tester at four different loads of 50N, 100N, 150N and 200N at a constant sliding speed of 0.75m/s. The results show that the wear rate of USV treated alloy increases almost linearly as the applied load increases from 50 N to 200N. The alloys made with semi-solid process exhibited improved wear resistance at the entire applied load range in comparison to the conventional casting alloys. At the applied load of 50N, oxidative wear is the dominant mechanism for the alloys with USV treatment. At 200N, a combination of delamination and oxidation wear is the main wear mechanism. The wear resistance of Al-17Si alloys containing 2% to 3% Fe is closely related to the morphology, size and volume fraction of Fe-bearing compounds, which can be changed by USV semi-solid process.

An indirect competitive immunoassay using quantum dots (QDs) as the fluorescent label has been developed for detection of melamine in milk products. The method exhibited a response for melamine with IC50 value of 11.3 ng mL-1 and a detection limit of 0.27 ng mL-1. Milk and milk powder samples spiked with melamine have been analyzed, and the method provided recoveries ranging from 84.2% to 108.0%, and a CV of 12.8%. The implementation of QDs provides for at least 30 fold improvement of detection limit when compared with optically-based ELISA screening methods that have been reported. The analytical performance in combination with simplicity of sample and antibody preparation provides the basis for a practical method for melamine detection.

Cellulose hydrogel was prepared from cellulose/NaOH aqueous solutions. Silica was added into cellulose hydrogel by TEOS hydrolysis method. Finally aerogel was obtained by the freeze-drying technique. The influence of silica on the properties of cellulose aerogel was studied in detail. With cellulose content 3%, the water absorption of cellulose-SiO2composite aerogel was only about 50% of the water absorption of cellulose aerogel. The result showed that silica could effectively reduce the water absorption of cellulose aerogel significantly and reduce the extent of structural damage that resulted from highly water absorption of cellulose aerogel. At the same time, with the increase of cellulose content, density of cellulose aerogel increased, while porosity decreased. It led to the water absorption of aerogel decrease with the increasing of cellulose content.

In the experiment, three kinds of wavy-walled tubes with different wave factor Fw were applied to study the effect of geometric parameters on mass transfer characteristics. Results show that mass transfer characteristics are influenced significantly by the oscillatory frequency and the wavelength of the wavy-walled tube. The peak value of the mass transfer enhancement is obtained at the multiple order oscillatory frequency, and the effective mass transfer enhancement is occurred when the wave factor Fw = 0.58. For the same Re number, the mass transfer enhancement factor E increases with the oscillatory fraction P, and the optimal Strouhal number St corresponding to different peak E almost does not change with P.

The hypereutectic Al-17Si-2Cu-1Ni-0.8Mn alloys with 2% or 3%Fe were fabricated out assisted with ultrasonic vibration (USV) treatment. The coarse plate-like δ-Al4(Fe,Mn)Si2 phase was transformed into fine particles with average diameter of about 17μm~20μm after USV treatment, and the volume fraction of particle-like Fe-bearing compounds is about 3.6%~5%. The polygonal primary Si crystals were also refined into particles with average diameter of about 15μm~23μm, and the volume fraction of primary Si declined to about 5.4%~6.5% after USV treatment. The matrixes of the castings were reinforced with fine Fe-bearing compounds and Si particles. The ultimate tensile strength of the alloys, which were produced by gravity casting process assisted with USV, increases with the increase of Fe content at 350 °C. It is considered the increase of the elevated temperature strength of the samples are mainly attributed to the refinement of δ-Al4(Fe,Mn)Si2 phase by USV and the increase of the volume fraction of the Fe-bearing compounds. The die casting process assisted with USV can further improve the mechanical properties of Al-17Si-2Fe-2Cu-1Ni-0.8Mn alloy.

Collaborative filtering recommendation algorithm is the most successful technology for recommendation systems. However, traditional collaborative filtering recommendation algorithm does not consider the change of time information. For this problem,this paper improve the algorithm with two new methods:Predict score incorporated with time information in order to reflect the user interest change; Recommend according to scores by adding the weight information determined by the item life cycle. Experimental results show that the proposed algorithm outperforms the traditional item in accuracy.

Recently determination of harmful elements in fertilizer has been paid growing attention. The determination method of cobalt in fertilizer by Wavelength Dispersive X-ray Fluorescence Spectrometry (WD-XRF) is developed. The calibration samples are made of blank compound fertilizer to simulate the matrix. The sample covered with microcrystalline cellulose is pressed at 35t for 60s, and cobalt content is determined by WD-XRF. This method has a good repeatability and accuracy with the linearity in the ranges of 0-2000mg/kg. The relative standard deviation is not more than 2.0%. The results obtained from WD-XRF and ICP-AES showed an acceptable agreement. 43 fertilizer samples are collected from 18 countries and determined. The cobalt contents are all not more than 13mg/kg.

According to the distribution of void fraction in water model of continuous casting mold, the influences of bubble size, water flow rate, and air flow rate on distribution of void fraction were studied by quasi single-phase model. The results indicated the distribution of void fraction generally showed a garlic shape. Both of the bubble diameter and the water flow rate have great influence on the distribution range of void fraction. Specifically the distribution range of void fraction increased with water flow rate and decreased with bubble diameter. And the gas flow rate has little effect on the distribution range of void fraction. The experiment results verified the authors model.

With cold rolling deformation between 12.5% and 60% for GH 536 superalloy strips, effect of deformation on the mechanical properties, texture formation and microstructure evolution have been investigated. The results show that an increase of deformation will lead to an increase of mechanical properties. As the deformation was 60%, the tensile strength and yield strength of the strip were 1430MPa and 1370MPa, respectively, and the elongation of strip was 4.5%. Also, an increase of deformation will lead to an increase of hardness, yield ratio and deformation resistance as well as an increase of rolling textures such as Goss {110}, S{213}, Copper {112} and especially Brass {110}. The optimized processing parameters of cold rolling deformation between 25% and 37.5% have been proposed to obtain an excellent formability and cold workability for GH 536 superalloy strips.

The microstructure and mechanical properties of Al-17Si-2Fe-2Cu-1Ni (mass fraction, %) alloys with 0.4% or 0.8% Mn produced by semi-solid casting process were studied. The semi-solid slurry of the alloys was prepared by ultrasonic vibration (USV) process. With USV process, the average grain size of primary Si in the alloys could be refined to 21~24μm, whether with or without P modification. The P addition has no further refinement effect on the primary Si in the case of the combined use of USV with P addition. Without USV, the alloys contain a large amount of long needle-like β-Al5(Fe,Mn)Si phase and plate-like δ-Al4(Fe,Mn)Si2 phase. Besides, the alloy with 0.8% Mn contains a small amount of coarse dendritic α-Al15(Fe,Mn)3Si2 phase. With USV treatment and semi-solid casting process, the Fe-containing compounds in the alloys are refined and exist mainly as δ-Al4(Fe,Mn)Si2 particles with average grain size of about 18μm, and only a small amount of β-Al5(Fe,Mn)Si phase is remained. With USV treatment and without P modification, the ultimate tensile strengths (UTS) of the alloys containing 0.4% and 0.8%Mn produced by semi-solid process are 260MPa and 270MPa respectively at room temperature, and the UTS are 127MPa and 132MPa at 350°C.

In mine power systems, false operation and failure operation of relays in parallel supply lines often take place when single phase grounding fault occurs. A novel method based on phase-to-phase current difference is proposed as line selection criterion in this paper. The method builds on that the phase-to-phase current difference based on fault phase in fault line is equal to the grounding fault current while the phase-to-phase current difference based on fault phase in sound lines is equal to zero. Thus the fault line was selected by the biggest phase-to-phase current difference of the lines. The simulation results using PSCAD and experiment results show that the method has a high accuracy and a great ability of anti-disturbance. It is quite effective when single-phase-to-earth fault occurs in one of the parallel supply lines. It also applies to any distribution system with different grounding patterns and won’t be affected by the value of grounding resistance or the degree of fault phase.

To aim at the characteristic of APF subject to external interference and at model uncertainty，a robust controller has been designed for the active power filter model based on the mixed sensitivity method, which is derived from control theory. We carried out several studies which have demonstrated that the controller is independent on the plant mode and the effect from the system uncertainty and disturbance can be greatly eliminated by the controller ，And thus can ensure both the internal stability and the robustness of the system. The digital simulation can prove the performance of the controller by MATLAB.

In order to improve the electrochemical performance of LiFePO4, Li0.99Nb0.01FePO4/C composite materials were synthesized with citric acid coating and Nb2O5 doping. The physical chemistry and electrochemical performances of Li0.99Nb0.01FePO4/C were investigated by X-Ray diffraction (XRD) and Transmission electron microscope (TEM). The results show that Li0.99Nb0.01FePO4/C has smooth charge-discharge voltage platform, with first capacity of 151.6 mAh•g-1 (0.1C) and no obvious capacity fading after 16 cycles. The materials have favorable high rate discharge performances, with the first capacity of 131.6 mAh•g-1 at 0.5C, 119.8 mAh•g-1 at 1.0C and 106.2 mAh•g-1 at 2.0C. Equivalent circuits analysis shows that the impedance, especially electrode reaction resistance of Li0.99Nb0.01FePO4/C are significantly reduced compared with the pure LiFePO4 and this helps to improve the electric conductivity, discharge capacity and cycle performance. The diffusion coefficient of Li+ in Li0.99Nb0.01FePO4/C is 2.51×10-12 cm2•s-1 increased two orders of magnitude in comparison with the pure LiFePO4. Carbon-coating makes a more remarkable contribution to lithium diffusion than Nb5+ ion doping.

With the acetates of nickel, manganese and cobalt as raw materials and lithium hydroxide as precipitation agent, the precursor Ni1 / 3 Co1 / 3 Mn1 / 3 (OH) 2 was first prepared by chemical coprecipitation method, which was then mixed and ballmilled with certain stoichiometric ratios of LiOH∙H2O, and ultimately obtained LiCo1/3Mn1/3Ni1/3O2 after calcination process. Single-factor experiment method, in conjunction with XRD, SEM, and charge-discharge test, was utilized to study the influence of various factors, including the dispersion way of precursor, pH value of reaction solution, and the content of ballmilling lithium on the electrochemical properties of LiCo1/3Mn1/3Ni1/3O2. The results indicated that: (1) the material dispersed by ultrasonic treatment revealed excellent cycling performance, its ratio of capacity fading decreased at least 34.1% compared to those without ultrasonic process; (2) the optimum conditions of fabricating LiCo1/3Mn1/3Ni1/3O2 may be summarized as the treatment of ultrasonic dispersion, suitable pH value (12~13) and stoichiometric ratio (1.0) of ballmilling lithium.

Fe-4Ni-0.5Mo-1Cu powder was selected as raw material, pressed and sinter-hardened at 1135°C for 30 min with rapid cooling. The density varies in the range of 7.24-7.29 g/cm3. Its fatigue properties have been tested in axial loading of alternating tensile/compressive stress at R=-1 with a servo-pulse pump. The fatigue endurance limit was measured to be 260 MPa. The microstructure showed more homogeneous bainite and martensite. Neither Ni nor Mo rich areas were detected. Fractography displayed the fatigue cracks initiated from the pore areas near the surface. A nontypical ductile fatigue striation was found. More dimples occurred on fracture surface due to the plastic deformation, which can prohibit cracking propagation and improve its fatigue properties.

X-ray analysis on iron ores and reduced iron powders revealed that around 60% acidinsoluble substances were hexagonal and tetragonal quartz, another 40% substances were sillimanite, alumina-silicate, an unnamed zeolite, all contained Si and Al. SEM images displayed that the particle size of them was in the range of 3~7 μm, which may be the initial source of the cracking in the sintered body. Statistics analysis showed that the Acid-Insoluble Content (AIC) for high-grade magnetite powder was (0.130±0.010) % during the latest five months. The predicting value for reduced iron powder from ore powders should be 0.179 %. However, the testing value for reduced iron powder was (0.192±0.014) %. The limited difference of 0.013% might imply rare pollution coming from the reduction and milling processes. The most important step for control AIC should be the separation process of iron ore powders.

The error function can be calculated based on the Simpson method through a subroutine program. An integration program by FORTRAN language was made for diffusion equations of extended source with infinite extent and limited extent. The distribution curves of alloying elements could be driven from calculated results written in ASCII code. The results on some alloying elements such as C, Co, Cr, Mn, Mo, Ni and V’s diffusion in iron, showed the diffusion distance for Ni and Mo can only be 1~3 μm and more distance for Co at common sintering temperature of 1120°C. Increasing the sintering temperature up to 1300°C, distribution curve could be improved. To refine the particle size of the added elements down to a scale of micrometers is an effective way to get homogeneous distribution.