Search

To provide insight into the mechanism of plasma catalytic oxidation of adsorbed benzene in a cycled storage–discharge (CSD) plasma catalytic process, ozone catalytic oxidation (OZCO) of adsorbed benzene over the AgMn/HZSM-5 (AgMn/HZ) catalyst at room temperature was studied. The properties of the AgMn/HZ catalyst were compared with those of HZ, Mn/HZ, Ag/HZ catalysts in investigations of the TPD of adsorbed benzene, the product distribution and O3 decomposition in OZCO of adsorbed benzene, and TPO and TPD of the used catalysts. For the AgMn/HZ catalyst, the adsorption capacity and the adsorption strength of benzene were significantly improved as compared to HZ, Ag/HZ and Mn/HZ. Adsorbed benzene is oxidized completely to CO2 by O3 catalyzed by Ag on HZ. MnOx, on the other hand, further speeds up the OZCO rate of benzene adsorbed on Ag/HZ.

In-situ regeneration of deactivated Au nanocatalysts during CO oxidation, was conducted effectively by pure oxygen plasma, but poisoned by dry air plasma in our previous work (Appl. Catal. B 2012, 119–120, 49–55). With extension of previous study, a simple and effective technique of atmospheric-pressure cold plasma of humid air is explored for in-situ regeneration of Au nanocatalysts. In comparison with ineffective regeneration by dry plasma, humid plasma using synthetic air (20% O2 balance N2) as discharge gas surprisingly exhibited effective regeneration performance over Au catalyst due to significant contribution of water vapor. After plasma regeneration for 5 min, the regeneration degree of Au catalysts significantly increased up to 98% under humid plasma in presence of 2.77 vol.% water, while decreased down to negative 29% under dry plasma. To disclose the mechanism of water vapor contribution to greatly improved regeneration degree, the characterizations of regenerated catalysts, and the analyses of electric discharge characteristics and gaseous products during the plasma regeneration were conducted. The significant contribution of water vapor embodies in that it speeds up the decomposition of carbonate species and simultaneously inhibits the formation of poisoning species of nitrogen oxides. Furthermore, normal air instead of synthetic air in humid plasma regeneration was implemented on the evaluations of the deactivated Au catalysts after a long-term reaction and during ten deactivation-regeneration cycles, which ensured the feasibility and reliability of in-situ plasma regeneration of Au nanocatalysts as a simple, effective and promising technique.

Driven by excellent CO oxidation capability of gold nanocatalysts at room temperature, a TiO2 supported Au nanocatalyst (Au/TiO2) was synthesized by deposition–precipitation method. To solve the deactivation issue of Au/TiO2 catalyst during CO oxidation, in-situ regeneration by N2/O2 plasma was employed. Pure O2 plasma could reversibly regenerate the deactivated Au/TiO2 catalyst, however, N2 addition resulted in an extra catalyst poisoning during regeneration. The extra poisoning effect was the most severe at 10% N2 and became much weaker at 80% N2. To investigate the formation of any surface poisoning species [NOy]s on Au/TiO2 catalyst, gaseous product of N2/O2 plasma over fresh Au/TiO2 catalyst was on-line analyzed by FT-IR, followed by catalyst characterization with temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The Au/TiO2 catalysts before and after plasma regeneration were also measured by transmission electron microscopy (TEM), in order to exclude the poisoning effect arisen from the change in gold particle size or morphology.

As the electrochemical oxidation technology is an effective and reliable clean technology, in this study the electrochemical oxidation activated sludge process was developed, in which the electrolysis reactor with homocentric circle arrangement electrode was installed, with Ti/RuO2 being used as reticular plates. The results showed that the electrochemical oxidation can reduce activated sludge production substantially. The lysis efficiency of activated sludge achieved was 29.98% in the experiment under the optimal oxidation conditions as follows: pH=12, 60 min of intermittent electrolysis time, working voltage of 6 V and initial VSS concentration of 4670 mg·L-1,while the SCOD and TP being released from cell lysis at the maximum of 712.2 and 33 mg·L-1 respectively; and the NH3-N also reached the maximum and presented a declining trend with operation time?, which showed that this conditions were the best for electrolysis oxidation of activated sludge.

At room temperature, the enhanced effect of water vapor on ozone catalytic oxidation (OZCO) of formaldehyde to CO2 over MnOx catalysts and the reaction stability was reported. In a dry air stream, only below 20% of formaldehyde could be oxidized into CO2 by O3. In humid air streams (RH≥55%), ∼100% of formaldehyde were oxidized into CO2 by O3 and the reaction stability was significantly enhanced. Meanwhile, in situ Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectra of OZCO of HCHO demonstrate that the amount of both monodentate and bidentate carbonate species on MnOx, in the dry stream, increased gradually with time on stream (TOS). However, in the humid stream, almost no accumulation of carbonate species on the catalysts was observed. To clarify the enhanced mechanism, formaldehyde surface reactions and CO2 adsorption/desorption on the fresh, O3 and O3+H2O treated MnOx catalysts were examined comparatively.

Adding O2 into biogas to achieve partial oxidation and CO2 mixed reforming can not only increase H2 þ CO concentration, but also reduce energy cost for H2 production. In this study, optimized mixed reforming of biogas with O2 addition in spark-discharge plasma was pursued in combination with thermodynamic-equilibrium calculation. With respect to mixed reforming of biogas with O2 addition in spark-discharge plasma, combination coefficients of independent reactions were given to quantitatively evaluate the mixed extent at various O2/(CH4eCO2) ratios. Compared thermodynamic-equilibrium with experimental results, it can be concluded that the optimal O2/(CH4eCO2) ratio for optimized mixed reforming of biogas in spark-discharge plasma was about 0.7. When total-carbon conversion was relatively high (>75%), H2 þ CO concentration on wet basis was the highest and energy cost for H2 production was the lowest at O2/(CH4eCO2) ¼ 0.7, and their experimental results were closest to their thermodynamic-equilibrium values.

Capacitively coupled plasma (CCP) is one of the most common industrial plasma sources. Experimental characterization plays key roles in understanding the complex physics involved in CCP, and is based on various probes, optical monitoring and mass spectrometry. Some recent configurations of capacitive discharge like dual frequency CCP, direct current CCP and electric asymmetric CCP have been extensively studied experimentally with these methods. In this paper, we review these recent experimental progresses of CCP studies.

Atmospheric-pressure (AP) linear cold plasma CVD is employed to deposit TiO2 photocatalytic films uniformly on a moving substrate. The in-plane and in-depth uniformities of the as-deposited TiO2 films are investigated by scanning electron microscopy (SEM) and UV-vis spectroscopy. The chemical binding states and compositions of the as-deposited TiO2 films are characterized by X-ray photoelectron spectroscopy (XPS). Raman, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectra prove the structures of the as-deposited and calcined TiO2 films are mainly hydro-oxygenated amorphous (a-TiOx:OH), and exclusively anatase, respectively. The photocatalytic activity of the as-deposited and calcined TiO2 films is evaluated in a continuous flow reactor for HCHO removal with simulated air. The activity of the as-deposited TiO2 films increases with film thickness, leveling off at about 780 nm. The activity of the as-deposited TiO2 film is lower than that of the calcined one.

Bulk Cu 50 Zr 40 Ti 10 amorphous alloy composites reinforced with carbon nanotube (CNT) were successfully fabricated by hot pressing technique. Their density, thermal conductivity, and mechanical properties were systemically investigated. The density and the compression strength of the compacts both decrease with increasing CNT content. The thermal conductivity of the compacts decreases when the CNT content is less than 0.10% or exceeds 0.60% (mass fraction), while increases when the CNT content is in the range of 0.1%–0.6%. The strain limit and the modulus of the compacts are obviously improved when the CNT content is less than 1.0% and then decrease significantly when the CNT content exceeds 1.00%. The optimum CNT addition is less than 0.20% at the comprehensive properties point of view.

A strong interaction between a metal oxide and support has long been indicative of its promotion of catalytic activities. In connection with this, we investigated the interaction of CuO with γ-Al2O3 and CeO2 for producing highly efficient catalysts for CO, C3H6, and NO abatement. In particular, the dispersion and thermal aging resistance of CuO clusters on different supports were studied. CuO clusters can be stabilized by interaction with CeO2, while on γ-Al2O3 they aggregated into larger particles at high CuO loadings. On the other hand, due to the poor thermal stability of CeO2, CuO clusters dispersed on it were sintered during an aging treatment at 950 °C. Accordingly, by pre-dispersing CeO2 on γ-Al2O3 followed by CuO dispersion, stabilized CuO clusters were obtained that were based on the superior aging resistance of the γ-Al2O3 support. Therefore, better catalytic performance and thermal aging properties were obtained with a CuO/CeO2/γ-Al2O3 catalyst as compared with CuO/γ-Al2O3 and CuO/CeO2 samples.

Cu 50 Zr 40 Ti 10 bulk amorphous alloys were fabricated by hot pressing gas-atomized Cu 50 Zr 40 Ti 10 amorphous powder under different consolidation conditions without vacuum and inert gas protection. The consolidation conditions of the Cu 50 Zr 40 Ti 10 amorphous powder were investigated based on an L 9 (3 4 ) orthogonal design. The compression strength and strain limit of the Cu 50 Zr 40 Ti 10 bulk amorphous alloys can reach up to 1090.4 MPa and 11.9 %, respectively. The consolidation pressure significantly influences the strain limit and compression strength of the compact. But the mechanical properties are not significantly influenced by the consolidation temperature. In addition, the preforming pressure significantly influences not the compression strength but the strain limit. The optimum consolidation condition for the Cu 50 Zr 40 Ti 10 amorphous powder is first precompacted under the pressure of 150 MPa, and then consolidated under the pressure of 450 MPa and the temperature of 380 °C.

Catalytic removal of indoor HCHO was proposed to proceed in a “storage-oxidation” cycling process. Two kinds of supported silver catalysts, namely Ag/HZSM-5 and Ag–MnO x –CeO 2, were investigated as catalysts for this cycling process. Due to the highly dispersed silver clusters formed and its good redox properties, the Ag–MnO x –CeO 2 catalyst showed better HCHO oxidation properties in both the storage phase (HCHO partial oxidation to HCOO − at room temperature) and oxidation-regeneration phase (total oxidation of the formates into CO 2 and H 2 O at elevated temperatures). The presence of H 2 O (RH = 50%, 25 °C) was found to enhance the HCHO storage capacity for Ag–MnO x –CeO 2 catalyst, while competitive adsorption of HCHO with H 2 O was observed over Ag/HZ catalyst. The results of DRIFTS indicate that the partial oxidation of HCHO into HCOO − is accelerated by the presence of H 2 O over the Ag–MnO x –CeO 2 catalyst. In addition, the catalyst saturated with HCHO can be in situ regenerated without production of secondary pollutants and can be used repeatly. It is suggested that this is a promising approach for indoor HCHO elimination.

Dry reforming of methane with CO 2 (DRM) was studied over Ni–Mo 2 C catalysts with Ni/Mo molar ratios of 1/3, 1/2, and 1/1 (denoted as Ni–Mo 2 C (1/3), Ni–Mo 2 C (1/2), and Ni–Mo 2 C (1/1), respectively) aiming to investigate the catalytic roles of Ni and the carbide. The results of XRD and XPS characterizations indicated that the carbonization process was promoted by the presence of Ni. The CH 4 -TPR and CO 2 -TPO over the fresh samples proved that CH 4 dissociation was greatly enhanced by Ni. The Ni–Mo 2 C (1/2) catalyst showed the best catalytic activity and stability for CH 4 /CO 2 (1/1) dry reforming. Above 80% of CH 4 and CO 2 conversions were maintained at 800 °C during a test run of 20 h at W/F = 0.3 g s cm −3 . Characterizations of the spent samples revealed that the deactivation of Ni–Mo 2 C (1/1) was due to coke formation whereas that of Ni–Mo 2 C (1/3) was due to bulk oxidation of Mo 2 C into MoO 2 . Only at a Ni/Mo molar ratio of 1/2, a catalytic oxidation–reduction cycle could be established. It was suggested that Ni–Mo 2 C was a typical bi-functional catalyst. In CH 4 /CO 2 dry reforming, the dissociation of CH 4 was catalyzed by Ni, while the activation of CO 2 took place on Mo 2 C. By regulating the molar ratio of Ni and Mo 2 C, a catalytic redox cycle could be established.

TiO2 film is deposited by atmospheric-pressure (AP), radio-frequency (RF), dielectric barrier discharge (DBD) plasma at a low power using titanium tetraisopropoxide (TTIP) and O2 as the precursors. The morphology, optical properties, and crystalline structure of the as-deposited TiO2 film are investigated by using scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet-visible (UV-vis) absorption spectroscopy, and Raman spectroscopy. The as-deposited TiO2 film show high photocatalytic activity in complete oxidation of HCHO to CO2 and degradation of stearic acid. The gas temperature in the RF-DBD plasma is estimated to be at about 500 K by the rotational temperature via optical emission spectroscopy (OES). The experimental results of amorphous TiO2 film treated by the RF-DBD plasma further exclude the likelihood of thermal effects derived from the plasma on crystallization of TiO2 film. It is confirmed that the non-thermal effect of the RF-DBD plasma on the high photocatalytic activity of the as-deposited TiO2 film does exist.

To produce high-concentration syngas (CO þ H2) from biogas, the effect of pressurization on dry reforming of biogas (CH4/CO2 ¼ 60%/40%) in kilohertz spark-discharge plasma was reported for the first time by elevating the pressure from 1 bar to 2 bar. It was found that elevating the pressure could not only increase the reactant conversions, but also reduce energy cost and increase fuel-production efficiency at the same specific energy input (SEI). In particular, pressurization exhibited a significantly positive effect on increasing CO2 conversion and decreasing energy cost for converting CO2. Syngas concentration as high as 83% (H2/CO ¼ 1.4) was achieved with a ratio of the flow rates of product gas (dry basis) to feeding gas, 1.7, at 2 bar and SEI ¼ 753 kJ/mol. The by-product, H2O, was produced with only about 5% of hydrogen-based selectivity in this work. At 2 bar, the effect of SEI was investigated by varying the power and flow rate, respectively. Compared with those at 1 bar, with the increase in SEI, reactants conversion increased fast, energy cost rose slowly and fuel-production efficiency decreased slowly at 2 bar.

Cu 50 Zr 40 Ti 10 amorphous alloy powder and Cu 60 Zr 30 Ti 10 plate-like ultrafine alloy powder were prepared by gas-atomization and ball-milling methods, respectively. Cu 50 Zr 40 Ti 10 bulk amorphous alloy (BAA) composites reinforced by Cu 60 Zr 30 Ti 10 alloy powder were fabricated by hot pressing method. The matrix of the composites remains a fully amorphous phase after consolidation process. The Cu 50 Zr 40 Ti 10 BAA composites exhibit improved plasticity and dramatically improved electrical and thermal properties by the Cu 60 Zr 30 Ti 10 powder addition. However, the density and compression strength of the BAA composites decrease with the increasing amount of Cu 60 Zr 30 Ti 10 alloy powder.

Amorphous Cu50Zr40Ti10 powder was fabricated in the particle size range

High energy cost and secondary pollutants formation makes the plasma-based technique impractical. To solve these problems, the effects of different catalysts, reactor configurations and operating conditions on plasma catalytic oxidation of stored benzene in a cycled storage-discharge process were investigated in detail. It is shown that the catalysts and reactor configurations were the main factors affecting the plasma catalytic oxidation of stored benzene. When 0.8 wt% Ag/HZSM-5 catalysts and in-plasma catalytic reactor are used, the stored benzene could be oxidized completely to CO2 in a very short discharge period and almost no secondary pollutant formation is observed. In addition, the relative humidity of air streams at storage stage showed little influence on the plasma catalytic oxidation of stored benzene. When the storage period increased from 1 to 14 h, a small increase of discharge period from 9 to 24 min was required to achieve ~100% conversion of stored benzene to CO2.

The Al-40Si alloy modified by 1.0 wt% Sr addition was heat-treated using L9(34) orthogonal test. The mechanical properties were measured. The microstructures were analyzed using optical microscope. After heat treatment, the hardness decreases about one times. The eutectic matrix and primary Si phase are both refined. The primary Si phase is refined and homogeneously distributes in the matrix with the solution temperature and time increasing. The optimal heat treatment condition is that the solution temperature, solution time, aging temperature, and aging time are 550 °C, 18 hours, 200 °C, and 5 hours, respectively. In addition, the theoretical optimal value for the hardness is 20.6 HRC, which is coherent with the practical optimal value.

Non-thermal plasma at atmospheric pressure was explored for the preparation of polysilicon from SiCl4. The power supply sources of positive pulse and alternating current (8 kHz and 100 kHz) were compared for polysilicon preparation. The samples prepared by using the 100 kHz power source were crystalline silicon. The effects of H2 and SiCl4 volume fractions were investigated. The optical emission spectra showed that silicon species played an important role in polysilicon deposition

The Al-40Si alloy modified by 0.5 wt% Sr addition was heat treated using L9(34) orthogonal test. The mechanical properties were measured. The microstructures were analyzed using optical microscope. After heat treatment, the extension percentage increases more than twice. The eutectic matrix and primary Si phase are both refined. The primary Si phase is refined and homogeneously distributes in the matrix with the solution temperature and time increasing. However, the primary Si phase agglomerates each other with further increasing of the solution temperature and time. According to the microstructure, the optimal solution temperature and time are 500 °C and 14 hours, respectively. In addition, the optimal values for the hardness, tensile strength, and extension percentage are 35.4 HRC, 82.2 MPa, and 2.05 %, respectively.

In this paper, surface residual stress in the cold working tool steel (Cr12MoV) by EDM was investigated by X-350 X-ray residual stress analyzer and method of DJP-2 electrolytic polishing instrument to remove layer by layer in the different EDM conditions. The results show that the distribution of surface residual stress generated not only by the peak discharge current and pulse width, but also by pulse interval. The same depth from the surface, residual stress of material after hardening is larger than the residual stress after annealing, With the different combination of tool electrode and work-piece material, the form of the discharge between two electrodes and the proportion of energy put between two electrodes are different, surface residual stress are also different. Different processing liquid for processing, the depth of residual stress generated is much the same, but closer to the surface, the worse the cooling capacity (quench degrees) and surface physical properties of processing fluids, the greater the residual stress. EDM, the generation and control of the surface residual stress depends on the choice such as processing power criteria, work-piece material, electrode materials and processing liquid. Surface residual stress after processing can be used to eliminate high-temperature heat treatment.

Cycled storage–discharge (CSD) plasma catalytic process was applied to low-concentration formaldehyde removal from air for the first time. HZSM-5, Ag/HZSM-5 (Ag/HZ), Cu/HZSM-5 (Cu/HZ) and AgCu/HZSM-5 (AgCu/HZ) catalysts were used for the process and their performance for formaldehyde storage and plasma catalytic oxidation of stored formaldehyde towards carbon dioxide was investigated in details. AgCu/HZ exhibited the highest formaldehyde adsorption capacity among these catalysts due to the synergistic effect of Ag and Cu, and it was very selective for oxidizing stored formaldehyde into CO2 by either oxygen or air plasmas at the discharge stage. The CSD process for lowconcentration formaldehyde removal had extremely low energy cost, excellent humidity tolerance and almost no secondary pollution. At the discharge stage, in addition to pure oxygen, air can also be used as the discharge gas for complete oxidation of formaldehyde, and the nitrogen oxides produced can be negligible because the discharge period was much shorter than the storage period. The stability of the AgCu/HZ catalysts during the CSD process was also investigated.

The Al-40Si alloy was modified by 0.5 wt% Sr addition and heat treated using the solution treatment and aging treatment. Its deforming capacity and hardness variance were investigated. The microstructures of the deformed samples were analyzed using optical microscope. The results show that the hardness increases with increasing of the deformation degree. When the deformation ratio exceeds 10.1 %, the hardness sharply increases. When the deformation ratio exceeds 20.4 %, the hardness maintains almost unchanged. In addition, although the cracks are not observed on the surface when the deformation ratio is less than 14.6 %, the primary Si phase is cracked. Thus the critical deformation ratio of the studied Al-40Si alloy is 10.1 %.

In this paper, the stabilization problem is studied by using multiple Lyapunov function techniques for a class of discrete-time switched linear singular (DSLS) systems. The existing criteria of stability for continuous-time switched singular systems are extended into DSLS systems. Then, a hybrid switching law is designed based on a partition of state space by using S-procedure method.

To investigate major methods of design and statistical analysis in controlled clinical acupuncture trials published in the West during the past six years (2003-2009) and, based on this analysis, to provide recommendations that address methodological issues and challenges in clinical acupuncture research.PubMed was searched for acupuncture RCTs published in Western journals in English between 2003 and 2009. The keyword used was acupuncture.One hundred and eight qualified reports of acupuncture trials that included more than 30 symptoms/conditions were identified, analyzed, and grouped into efficacy (explanatory), effectiveness (pragmatically beneficial), and other (unspecified) studies. All were randomized controlled clinical trials (RCTs). In spite of significant improvement in the quality of acupuncture RCTs in the last 30 years, these reports show that some methodological issues and shortcomings in design and analysis remain. Moreover, the quality of the efficacy studies was not superior to that of the other types of studies. Research design and reporting problems include unclear patient criteria and inadequate practitioner eligibility, inadequate randomization, and blinding, deficiencies in the selection of controls, and improper outcome measurements. The problems in statistical analysis included insufficient sample sizes and power calculations, inadequate handling of missing data and multiple comparisons, and inefficient methods for dealing with repeated measure and cluster data, baseline value adjustment, and confounding issues.Despite recent advancements in acupuncture research, acupuncture RCTs can be improved, and more rigorous research methods should be carefully considered.

The effect of the Sr + RE complex modifications on microstructure and mechanical properties of Al-40 wt% Si alloy were investigated. The results show that Sr + RE complex modification not only on primary silicon and eutectic silicon with modification, but also on dendrite α significantly refine. When the addition of RE remain unchanged, with increasing of the addition of Sr, the primary silicon firstly changes from polygonal block or large plate to small block, then to large polygonal block, edge and corner passivations. The eutectic silicon firstly changes into a fine start with a long needle-like fibrous or branched further to a short stubby dendrite or worm-like, The eutectic silicon changes from needle to a fibrous sheet plus short rod, then to short rod end for the dense, or even granular. The dendrite α changes from highly developed dendritic to equiaxed and uniform distribution. In addition, with increasing of the addition of Sr, the mechanical properties has been significantly improved, tensile strength increased by 37%, elongation is more than double, the hardness increased by 21%. When the Sr addition is between 0.05 wt% and 0.077 wt%, the microstructure and mechanical properties are the best.

A green process for the oxygen-free conversion of methane to high-concentration ethylene and hydrogen in a plasma-followed-by-catalyst (PFC) reactor is presented. Without any catalysts and with pure methane used as the feed gas, a stable kilohertz spark discharge leads to an acetylene yield of 64.1%, ethylene yield of 2.5% and hydrogen yield of 59.0% with 80.0% of methane conversion at a methane flow rate of 50 cm3/min and a specific input energy of 38.4 kJ/L. In the effluent gas from a stable kilohertz spark discharge reactor, the concentrations of acetylene, ethylene and hydrogen were 18.1%, 0.7% and 66.9%, respectively. When catalysts Pd-Ag/SiO2 were employed in the second stage with discharge conditions same as in the case of plasma alone, the PFC reactor provides an ethylene yield of 52.1% and hydrogen yield of 43.4%. The concentrations of ethylene and hydrogen in the effluent gas from the PFC reactor were found to be as high as 17.1% and 62.6%, respectively. Moreover, no acetylene was detected in the effluent gas. This means that a high concentration of ethylene and oxygen-free hydrogen can be co-produced directly from methane in the PFC reactor.

The spark-discharge plasma, generated between tubular and rotary-disc electrodes using a sine-wave high voltage with 5 kHz frequency, was explored for CO2 reforming of CH4. Based upon the investigation on the effects of specific energy input and CO2/CH4 ratio, the energy costs (EC) and fuel-production efficiencies (η) at various CO2/CH4 ratios (r) in the same conversion range were compared and accordingly their sequences were given: EC (r = 0.5) and EC (r = 3) are the lowest; η(r = 0.5) is the highest. Compared with other nonthermal discharge techniques, the kilohertz spark discharge exhibits low EC and high fuel-production efficiency, especially at high total-carbon conversions. Preliminary investigation on partial oxidation and CO2 mixed reforming at (O2 + CO2)/CH4 = 0.5 exhibited high H2/CO ratio (nearly 2) and low total-carbon EC (0.59–0.96 MJ/mol, 58–77% of total-carbon conversion, and O2/(CO2 + O2) = 0.8). © 2010 American Institute of Chemical Engineers AIChE J, 2011

The effects of heat treatment on morphology of primary α and hardness of B-refined Al-7 wt% Si alloy are investigated. In addition, the optimum heat treatment procedure is also determined. It is shown that, at 450°C with different holding time from 3h to 12h, morphology of primary α phase is converted from irregular dendrite to granular homogeneous equiaxed grains then to rosette structure. The primary α phase is gradually converted from dendrite into the rosette dendrite and then into particle crystal with increasing of temperature by holding 8h at 300~540°C. One can find fine and uniform distributed particle α phase at 400°C or 450°C. However, the primary α phase has changed into large and irregular shape when the temperature increases up to 450°C. The orthogonal analysis shows that the optimum heat treatment parameters are 540±10°Cand 6h.

The ribbon samples for Cu60Zr30Ti10 (at. %) with a thickness of 50 μm and a width of 13 μm were prepared by melt spinning at the wheel speed of 30 m/s. The glassy structure was confirmed by X-ray diffraction (XRD) using Cu Kα radiation. The corrosion property and corrosion mechanism in 1 M HCl, 1 M NaCl, and 0.5 M H2SO4 solutions were investigated by electrochemical polarization measurement. The corrosion mechanisms are dominated by the pitting corrosion in H2SO4 solution and the pitting and uniform corrosion in HCl and NaCl solutions. In addition, the corrosion resistance in H2SO4 solution is better than that in HCl and NaCl solutions. Cu60Zr30Ti10 glassy alloy in H2SO4 solution is nobler than in HCl and NaCl solutions.

The influence of Zr on the property of Cu(50+x)Zr(40-x)Ti10 (0≤x≤30 at.%) alloys were investigated. The results show that the maximum size for the glass formation in this Cu-Zr-Ti system is less than 8 mm. The hardness increases with decreasing of the Zr content, then decreases when the Zr content exceeds 10~15 at.% due to the obvious alteration of the type of the crystalline phases and the microstructure. With decreasing of the Zr content, the transformation sequence of the main Cu-Zr phase is Cu10Zr7→Cu5Zr→Cu51Zr14; the transformation sequence of Cu-Ti phase is Cu4Ti3→CuTi→CuTi3. In addition, the atom ratio of Cu60Zr30Ti10 alloys is coherent with that of their corresponding crystalline phase, resulting in its better glass forming ability.

The glass forming ability, thermal stability and non-isothermal crystallization kinetics of Zr64Al10.1Cu11.7Ni14.2 glass forming alloy were investigated. Its maximum glass forming dimension is up to 5mm and its critical cooling rate is less than 40Ks-1. The apparent activation energies derived from the Kissinger for Eg, Ex, Ep1 and Ep2 are 244.97±12.90, 264.63±10.18, 268.75±40.10 and 222.34±24.12 KJmol-1, respectively. The fragility parameter m is about 20.27, indicating its better thermal stability and glass forming ability.

The effect of Sr on the microstructures and mechanical properties of Al-20 wt% Si alloys were investigated. The results show that with increasing of the Sr content, the primary silicon firstly changes from polygonal block or large plate to small block, then to large polygonal block, and a large number of honeycomb-like on the primary silicon block. The eutectic silicon firstly changes into a fine start with a long needle-like fibrous or branched further to a short stubby dendrite or worm-like, continuously columnar dendrite α of quantity increase. In addition, with increasing the Sr content, the elongation of alloy increases, but there are ups and downs, the tensile strength changes little after the first sharp increases in hardness is parabola. When the Sr content is between 0.04 wt% and 0.06 wt%, the morphology and mechanical properties is the most ideal.

The glass forming ability (GFA), thermal stability, non-isothermal crystallization kinetics, and mechanical property of Zr 61.5 Al 10.7 Cu 13.65 Ni 14.15 glass forming alloy were investigated. Its maximum glass forming dimension reaches up to 5.5 mm and its critical cooling rate is less than 40 K s −1 . The apparent activation energies for glass transition E g , onset crystallization E x , and crystallization peak E p are 214.56 ± 16.14, 267.42 ± 9.36, and 305.69 ± 7.31 kJ mol −1 , respectively. Small fragility parameter m about 17 indicates its better thermodynamic stability and GFA. In addition, its elastic strain limit, compressive strength, and Young's modulus are 2.73%, 1.81 GPa, and 70.47 GPa, respectively. Its V-shape fracture mode is different form other bulk metallic glasses.

The glass forming ability, thermal stability and non-isothermal crystallization kinetics of Zr 63.5 Al 10.7 Cu 10.7 Ni 15.1 glass forming alloy were investigated. Its maximum glass forming dimension is up to 6 mm and its critical cooling rate is less than 40 K s −1 . It manifests two crystallization procedures and the second crystallization peak is more sensitive to heating rate than the first crystallization peak. The glass transition and crystallization both have remarkable kinetics effects. The m s fitted by Arrhenius and VF equations are consistent with each other. Small m value about 17 indicates better thermodynamic stability and GFA of Zr 63.5 Al 10.7 Cu 10.7 Ni 15.1 .

The conversion of methane in electric discharges of different types and under electron beam irradiation are considered. The influence of nonequilibrium conditions of conversion in low-temperature plasma on the energy consumption, product composition, and selectivity is analyzed. The results of works on plasma pyrolysis, partial plasma oxidation, and steam and carbon dioxide reforming of methane in a low-temperature plasma are discussed. It is shown that the use of chain processes makes it possible to substantially reduce the power consumption for methane conversion by an electrophysical device.

Toward achieving selective catalytic reduction of NOx by hydrocarbons at low temperatures (especially lower than 200 °C), C2H2 selective reduction of NOx was explored on H-mordenite (H-MOR) catalysts in dielectric barrier discharge (DBD) plasma. This work reported significant synergistic effects of DBD plasmas and H-MOR catalysts for C2H2 selective reduction of NOx at low temperatures (100–200 °C ) and across a wide range of O2 content (0–15%). At 100 °C, NOx conversions were 3.3, 11.6 and 66.7% for the plasma alone, catalyst alone and in-plasma catalysis (IPC) cases (with a reactant gas mixture of 500 ppm NO, 500 ppm C2H2, 10% O2 in N2, GHSV = 12,000 h−1 and input energy density of 125 J L−1), respectively. At 200 °C, NOx conversions were 3.8, 54.0 and 91.4% for the above three cases, respectively. Also, strong signals of hydrogen cyanide (HCN) byproduct were observed in the catalyst alone system by an on-line mass spectrometer. By contrast, almost no HCN was detected in the IPC system.

In present work, the characteristics of three methods such as the orthogonal design, Fuzzy optimum method and artificial neural network modeling technique were made on the basis of the optimization and evaluation of the performance of the phosphate graphite mold. The variance analysis indicates that the phosphoric acid has greatest influence on both compression strength and tension strength of phosphate graphite mold, both drying temperature and drying time greater, and Al 2 O 3 minor, respectively. The Fuzzy multi-objective comprehensive evaluation shows that the optimum technology for phosphate graphite mold designed by us is phosphoric acid 30%, Al 2 O 3 30%, drying temperature 400 °C and drying time 60 min. In addition, the ANN can be used to establish mono- and multi-objective models for the prediction of other tests outside orthogonal test with rather high accuracy. However, the predicted results are worse for the linear regressive equations by the orthogonal analysis.

In present work, the compression strength and tensile strength of phosphate graphite sand with compositional and technological parameters (phosphoric acid, Al2O3, drying temperature, and drying time) were experimentally investigated. An L9 (34) orthogonal array was employed to analyze the effect of these four parameters on the compression strength and tensile strength, respectively. In addition, the radial basis function artificial neural network (RBFANN) was used to establish the models for compression strength and tensile strength, respectively. Moreover, the simulation and prediction results by the RBFANN and linear and non-linear regressions are compared. The results are as follows: the optimum scheme for phosphate graphite sand designed by us is phosphoric acid 24%, Al2O3 30%, drying temperature 400 °C, and drying time 60 min. The ascending sequence of the effect of four factors on both compression strength and tensile strength of phosphate graphite sand is drying time, drying temperature, Al2O3, and phosphoric acid. In addition, the prediction and simulation results show that RBFANN outperforms Taguchi approach for modeling.

Spectral analysis plays a significant role onplant characteristic identification and mechanism recognition, there were many papers published on the aspects of absorption features in the spectra of chlorophyll and moisture, spectral analysis onvegetation red edge effect, spectra profile feature extraction, spectra profile conversion, vegetation leaf structure and chemical composition impacts on the spectra in past years. However, fewer researches issued on spectral changes caused by plant seasonal changes of life form, chlorophyll, leaf area index. This paper studied on spectral observation of 11 plants of various life form, plant leaf structure and its size, phenological characteristics, they include deciduous forest with broad vertical leaf, needle leaf evergreen forest, needle leaf deciduous forest, deciduous forest with broadflat leaf, high shrub with big leaf, high shrub with little leaf, deciduous forest with broad little leaf, short shrub, meadow, steppe and grass. Field spectral data were observed with SVC-HR768 (Spectra Vista company, USA), the band width covers 350-2 500 nm, spectral resolution reaches 1-4 nm. The features of NDVI, spectral maximum absorption depth in green band, and spectral maximum absorption depth in red band were measured after continuum removal processing, the mean, amplitude and gradient of these features on seasonal change profile were analyzed, meanwhile, separability research on plant spectral feature of growth period and maturation period were compared. The paper presents a calculation method of separability of vegetation spectra which consider feature spatial distances. This index is carried on analysis of the vegetation discrimination. The results show that: the spectral features during plant growth period are easier to distinguish than them during maturation period. With the same features comparison, plant separability of growth period is 3 points higher than it during maturation period. The overall separabilityof vegetation spectrum features shows seasonal amplitudeseasonal gradientseasonal mean during the growth period, but the separability of seasonal gradient shows highest value for the plant seasonal NDVI change. Therefore, the features of seasonal NDVI gradient, seasonal amplitude of maximumspectral absorption depth in green band, seasonal amplitude of maximumabsorption depthin red band are effective composition for plant discrimination.

We propose an expression, ΔG = ΔHm[{α(T − Tm)/(1 − α)Tm}+{T/(1 − α)Tm}ln(Tm/T)] (0 1 ), for the calculation of Gibbs free energy difference ΔG of multi-component metallic alloys. The results show that the theoretical ΔGs are in better agreement with the experimental values over entire under-cooling range than those given by the TS, KN1 and KN2 expressions. The glass-forming ability of the multi-component metallic alloys has been observed to increase with the increase in the difference of the glass transition temperature and isenthalpic temperature.

A novel process consisting of a pulsed streamer discharge over Ni/HZSM-5 catalysts for an oxygen-free conversion of methane to aromatics is reported here. This plasma-over-catalyst process shows a significant synergetic effect on promoting methane conversion to aromatic products and high stability. Using this process at atmospheric pressure and a temperature of 573 K, significant amounts of aromatics have been obtained.

The development and application of the component design methods for bulk metallic glasses are summarized. And then, their application scopes are analyzed, respectively. Moreover, we propose a new method titled as similitude principle and artificial neural network model (SPANNM) for the component design and glass forming ability of bulk metallic glasses. It is shown that the predicted results by the SPANNM are in better agreement with the experimental values.

Silicon carbide (SiC) MOSFET is a new type of high voltage power switching device, featuring by low on-state resistance and fast switching speed. In recent years, it has received extensive research and application due to its prominent advantages of high temperature and high frequency, the comparisons and analysis of switching characteristic of SiC MOSFET and traditional silicon (Si) MOSFET is of great importance. In this paper, a test platform based on H-Bridge double-sided LCC ZVS resonant network is presented. The switching waveforms, switching time, turn-off voltage change rate (dv/dt), turn-on current change rate (di/dt), turn-off spike voltage, switching energy loss of SiC MOSFET, Si CoolMOS and Si MOSFET were compared and analyzed. Finally, the system efficiency and the temperature rise of the heat sink are compared using three kinds of MOSFET under the same output power and environment temperature. Experimental results show that SiC MOSFET switching time is the shortest and the turn-off voltage is small, the energy loss is the lowest under the same test environment.

Double LCC compensation resonant converter is effectively applicable to inductively coupled energy transfer, for the advantages of perfect symmetry and simple design. However, the system gain characteristics and output characteristics of the circuit overall structure were ignored in the previous study of double LCC compensation converter. In this paper, impedance analysis method is used to determine gain characteristic of system, finding that the system has a constant current source output characteristics in addition to purely resistance at a fixed frequency point, which is independent of the load and the coupling coefficient. Two methods of parameters optimization are proposed in this paper, which are used to realize ZVS (Zero Voltage Switch) for the full-bridge inverter. Subsequently, the effects of different methods on the gain characteristics are compared. A design idea of a double LCC compensation topology under different working conditions is provided. The whole optimization method is simple, accurate and practical. Finally, a 3.3 kW double LCC resonant converter is completed. The characteristics of the converter and optimization method are verified from simulation and experimental results.