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A catalyst with high NO conversion rate and good sulfur resistance is the key to CO-SCR. Herein, the V-doped OMS-2 molecular sieves were successfully synthesized through the hydrothermal method. The resulting catalyst was characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope(TEM) and specific surface area analyzer (BET). The results showed that the addition of V increased the average grain size of OMS-2 and the concentration of oxygen vacancies. Meanwhile, V replaced the K site in OMS-2 and participated in the oxidation-reduction reaction together with Mn. Compared with the V0-OMS-2, the NO conversion rate of V0.2-OMS-2 in a sulfur-free environment increased from 60% to 81% at 150 °C and 75%–94% at 300 °C. The NO conversion rate could still maintain as 80% at 300 °C in a sulfur-containing environment.

The effects of CaF2 (1–5 wt.%) on the glass structure, crystallisation behaviour, sinterability, microstructure, and properties of a CaO–MgO–Al2O3–SiO2 glass-ceramic system were investigated. The results show that the glass transition temperature, crystallisation peak temperature and the activation energy for crystallisation decreased with the addition of CaF2. The crystallisation of diopside was initiated at the particle boundaries and followed with progressive advancing towards the centre. The enhanced crystallisation for CaF2-containing samples was observed and is likely due to the depolymerisation of the glass structure. However, the enrichment of Ca–2F complexes resulted in fluorite phase precipitation at the crystallisation front of the diopside phase when the CaF2 addition exceeded 3 wt.%. The hindered viscous flow sintering from a lower crystallisation temperature led to a decline in the sintering shrinkage, the extent of which was proportional to the amount of added CaF2. Plastic deformation was observed along with the newly-formed amorphous phase as the sintering temperature approached the glass melting point, which benefits densification. The performance analysis reveals that the fabricated glass-ceramics with the proper addition of CaF2 exhibited significant improvements in its density and bending strength. Whereas, the Vickers hardness, water absorption and chemical resistance all decreased.

This study explores the roles of Fe2O3 (3–5 wt%) and/or MgO (0.6–2.4 wt%) on the crystallization behaviour, microstructure, sinterability and mechanical properties of 17.02CaO-7.04Al2O3-58.84SiO2 (CAS, wt%) glass-ceramics. With increasing Fe2O3 and/or MgO contents, the peak temperature of glass crystallization decreased, and the main crystal phase (wollastonite) was suppressed, while the secondary phases of hardystonite and diopside were crystallized and promoted. Wollastonite crystals grew larger, and their distribution became scattered as Fe2O3 and/or MgO contents increased. The concentrations of elemental Fe and Zn in the glass matrix influence the formation of hardystonite (Ca2ZnSi2O7), and Mg2+ can participate in the formation of diopside and melilite-type solid solution Ca2ZnSi2O7-Ca2MgSi2O7. Vickers hardness was decreased by the increasing amount of glass matrix while density was increased. The optimum heat treatment temperature range of the CAS glass-ceramics was narrowed by the addition of Fe2O3 and/or MgO due to rapid crystallization and a degree of fusion or overburning.

This study illuminates the role of low amounts of magnesia (≤ 3 wt%) on the crystallization behaviour of CaO-Al2O3-SiO2 glass-ceramics. Differential thermal analysis demonstrates that the peak temperature and activation energy for crystallization decrease with the addition of MgO. The crystallization pattern changes from one-dimensional crystallization to two-dimensional growth, as indicated by higher values of the Avrami parameter (n) with increasing MgO contents. Analyses of the Rietveld refinement of XRD data, FTIR, Raman spectra and scanning electron microscopy reveal that MgO causes a simple change in CaO-Al2O3-SiO2 glass-ceramics, which form an Mg-containing solid solution (Ca1-xMgxSiO3; 0 ≤ x ≤ 1) by replacement of some of the CaO with small amounts of MgO. When the MgO content increases to 1.8 wt%, diopside is primarily formed at the interfaces of sintered glass frits, acting as nucleation sites for the inward growth of wollastonite. The density of glass-ceramics increases with magnesia addition. Their hardness is strongly influenced by the phase species present, and can be enhanced by the crystallization of diopside.

The vibrating flip-flow screen (VFFS) is a high-efficiency device currently used for deep screening of moist fine-grained materials. During VFFS operation, the normal operation of the screen is affected by fatigue damage to the shear springs arranged symmetrically on both sides of the screen, leading to equipment failures and disruption production. In this paper, the shear spring&rsquo, s static and dynamic characteristics in different operation conditions were studied using the INSTRON 8801 fatigue test system and Dynacell dynamic sensors. Using an experimental test of shear spring stiffness and damping coefficients, the effects of some factors, i.e., temperature, hardness, amplitude and frequency, were studied. The results show that the temperature of the shear spring on the left side of the flip-flow screen was higher than that of the right side (driving side). With an increase in temperature, the stiffness of the shear spring decreased. With the increase in amplitude, the dynamic stiffness decreased and the damping coefficients did not change, with the increase in frequency, the dynamic stiffness increased and the damping coefficient decreased. At the same amplitude, with the increase in hardness of the shear spring, the dynamic stiffness increased. Finally, the stiffness and damping coefficients of the shear spring before and after tearing were obviously reduced. These research results reveal the relationship of the characteristics of a shear spring with operational conditions, and could provide a theoretical reference for the design of the VFFS and the selection of the shear spring.

The tensile properties of TiNi43.5Fe6.5 alloy samples having different grain sizes (0.16, 0.35, 1.7, 2.3, and 3.9 μm) and fabricated by severe plastic deformation and annealing were investigated. I...

In order to improve the uneven flow of exhaust in traditional catalytic gasoline particulate filter system (C-GPFs) and improve the regeneration performances under low-temperature conditions, the new C-GPFs integrated regeneration model is established and explored. In this work, firstly, the NO catalytic rate and soot combustion rate are defined as the evaluation indicators of the new C-GPFs integrated regeneration performances. Secondly, based on the numerical simulation software, the regeneration performances of the new C-GPFs with and without electric heating are compared and analyzed, and the calculation model is verified based on the engine experiments. Then, the effects of four different structure parameters on the regeneration performances of the new C-GPFs are studied. Finally, through the orthogonal experiments, the influence weights of the four parameters on NO catalytic rate, soot combustion rate, and pressure drop are explored, and the new C-GPFs are optimized under simulation conditions. The results show that after optimization, the NO catalytic rate is enhanced by 2.1%, the soot combustion rate is enhanced by 11.9%, and the pressure drop is increased by 3%. This work provides an important reference value for improving the integrated regeneration performance of the C-GPFs in a gasoline engine.

The soot combustion performance of catalytic gasoline particulate filter regeneration system (C-GPFs) can be significantly improved by increasing the temperature of gasoline exhaust gas at low-temperature conditions. In this paper, firstly, the soot oxidation rate is introduced as an evaluation index for the combustion performance of C-GPFs, and a suitable electric heating power is defined. Secondly, based on the computational fluid dynamics software, the traditional and improved electric heating C-GPFs combustion performance is compared and analyzed, and the accuracy of the improved electric heating C-GPFs model is verified through experiments. Finally, the effects of critical exhaust parameters on the soot combustion performance and electric energy consumption of the electric heating C-GPFs is studied by numerical simulation. The results of the study show that: the electric energy consumption under the suitable electric heating power is reduced by 49.6% as the exhaust flow rate decreases from 0.023 kg/s to 0.017 kg/s. The electric energy consumption under the suitable electric heating power is reduced by 50.4% as the exhaust temperature increases from 558 K to 588 K. The electric energy consumption under the suitable electric heating power is reduced by 31.6% as the exhaust oxygen concentration increases from 1.6% to 2.4%. The electric energy consumption under the suitable electric heating power is reduced by 34.7% as the exhaust NO concentration increases from 0.08% to 0.12%. Finally, this work provides a direction for improving the soot combustion performance in gasoline engines at low-temperatures.

The high pollutant emissions during the cold start of gasoline engines have aggravated the greenhouse effect and environmental pollution problems. In order to better control the pollutant emissions during cold start and save power consumption, an improved catalytic gasoline engine particulate filter regeneration system (C-GPFs) with electric heating is proposed, and its combustion performance is studied. In this work, firstly, the soot oxidation rate is introduced as an evaluation index of the combustion performance, and the suitable electric heating power is defined. Secondly, the combustion performances of traditional and improved electric heating C-GPFs are compared and analyzed. The results show that when the electric heating power is the same, the length and volume of the improved C-GPFs are smaller, and the soot oxidation rate is higher. Then, the effects of critical filter structure parameters on the combustion performance and electric energy consumption of the improved electric heating C-GPFs is studied by numerical simulation. The results show that when the filter cell density increases from 250 cpsi to 400 cpsi, the filter wall thickness decreases from 0.45 mm to 0.35 mm, the α ratio decreases from 3:2 to 2:3, and the filter diameter increases from 90 mm to 110 mm, the electric energy consumption when reaching the suitable electric heating power is reduced by 17%, 13.2%, 30.4%, and 21%, respectively. Finally, this work provides a reference value for improving the pollutant emission control effect and saving power consumption during the cold start of the gasoline engines.

In catalytic gasoline particulate filter (CGPF), the higher soot oxidation rate and lower pressure drop symbolize the good soot combustion performance. In this work, the index for evaluating the catalytic efficiency is defined. Then, the effects of filter structural parameter on the catalytic efficiency and soot combustion performance of CGPF when it reaches equilibrium state are investigated through numerical simulation. The change rules of gasoline engine power and brake specific fuel consumption (BSFC) are analyzed by using the GT-power software. The results indicate that properly increasing the filter porosity, filter length, and filter diameter, or decreasing the filter wall thickness is beneficial for the improvement of soot combustion performance. For practical application, CGPF will obtain the best soot combustion performance when the filter porosity is 0.46, the filter wall thickness is 0.2 mm, the filter length is 200 mm, and the filter diameter is 158 mm. Comparing the optimized structural size with the initial structural size, the catalytic efficiency increases by 5.3%, the soot oxidation rate increases by 24.1%, and the pressure drop decreases by 37.5%. Based on GT-power modeling and analysis, the optimized CGPF reduces the BSFC by 2.6% and increases the power by 8.9%.

This work aimed to further improve the combustion performance in a diesel Wankel engine by optimizing the assisted ignition strategy. Based on the established and verified dynamic simulation model, the effects of some key assisted ignition parameters, such as the number of assisted spark plug, assisted ignition position (AIP) and assisted ignition timing (AIT) on combustion performance were analyzed systematically. Simulation results indicated that the reaction process occurred in the mid-anterior region of the rotary chamber due to the stratified-charge mixture and forward-propagate flame. The combustion performance of the double assisted spark plug schemes was better than that of the single assisted spark plug scheme. The double assisted spark plugs symmetrically distributed relative to the major axis (X-axis) of the rotary chamber, the combustion process was more reasonable. When changing AIP, peak combustion pressure (Pmax) and combustion zone varied greatly, while they changed little when advancing AIT. For the optimized assisted ignition strategies, the optimal AIP scheme was Case5 (0, −88.5, ±15 mm) and the optimum AIT scheme was Case7 (35°CA BTDC). Comparing with the original scheme (Case1), their Pmax increased by 16.68% and 17.83%, respectively. Meanwhile, the CA50 and CA10-90 were shortened obviously.

The high NO2 concentration in the gasoline engine exhaust gas is beneficial to improve the regenerative equilibrium performance of the catalytic particulate filter regeneration system. In this work, the effect of exhaust parameters on NO conversion efficiency of a dual-carrier catalytic converter is simulated. The reliable operating temperature range and NO2 mass fraction distribution of dual-carrier catalytic converter under different exhaust parameters are analyzed and the simulation results are verified by the experimental values. The main results are presented as follows: (1) The maximum of NO conversion efficiency is 68% when the exhaust gas temperature is 600 K. (2) The maximum value of NO conversion efficiency is increased by 30% when the exhaust gas flow is reduced from 0.025 kg/s to 0.01 kg/s (3)The maximum value of NO conversion efficiency is increased by 14% when the oxygen concentration from the exhaust is increased from 1.4% to 5%. (4) The orthogonal experimental results show that when the exhaust gas temperature is constant at 600 K, the exhaust gas flow has the most significant influence on the NO conversion efficiency. Finally, some guidelines are proposed to improve the NO conversion efficiency of the dual-carrier catalytic converter.

The high NO2 concentrations in the gasoline engine exhaust gas are beneficial to improve the regenerative equilibrium performance of the catalytic particulate filter regeneration system. In this work, the effect of critical dual-carrier structure parameters on NO conversion efficiency of the dual-carrier catalytic converter is explored by using the numerical simulation method. The reliable operating temperature range of the dual-carrier catalytic converter under critical dual-carrier structure parameters and the distribution of NO and NO2 mass fraction under the equilibrium state of the catalytic reaction are analyzed. Based on GT-Power software, the variation law of the brake specific fuel consumption (BSFC) and power is studied. The main results are presented as follows: The maximum conversion efficiency of NO is increased from 63% to 67% when the dual-carrier cell density ratios are increased from 300 cpsi/400 cpsi to 500 cpsi/400 cpsi. The maximum NO conversion efficiency of NO is increased from 64% to 66% when the dual-carrier wall thickness ratios are decreased from 0.24 mm/0.17 mm to 0.10 mm/0.17 mm. The maximum conversion efficiency of NO remains about 65% when the dual-carrier length ratios are increased from 30 mm/70 mm to 70 mm/30 mm. The maximum conversion efficiency of NO is increased from 58.5% to 74% when the carrier diameter is increased from 80 mm to 120 mm. And after optimization, the BSFC of the gasoline engine system is reduced by 2% while the power is increased by 7.2%. Finally, some guidelines are proposed to reduce the BSFC and increase the power of the gasoline engine system, while improving the NO conversion efficiency of the dual-carrier catalytic converter.

In order to investigate the exhaust parameters how to influence the particulate purification performance of the gasoline particulate filter (GPF), the importance of exhaust parameters on the temperature and pressure drop in the regeneration equilibrium state of the gasoline particulate filter is studied by using the numerical simulation software FLUENT. The distribution law of optimal temperature in the regeneration equilibrium state and pressure growth rate of the gasoline particulate filter under different exhaust parameters is analyzed, and the numerical simulation results are compared with the experimental values of the literature to verify the accuracy of the numerical research. The main results are presented as follows: (1) The temperature and pressure drop in the regeneration equilibrium state is decreased by 2.1% and 6.4% when α value is increased from 4 to 8, respectively. (2) The temperature and pressure drop in the regeneration equilibrium state is increased by 2.7% and 26.5% when the exhaust temperature is increased from 400 K to 500 K, respectively. (3) The temperature in the regeneration equilibrium state is increased by 2.5%, and the pressure drop is increased by 12.3 times when the exhaust flow rate is increased from 0.001 kg/s to 0.01 kg/s. Finally, the results of the orthogonal experiment show that the exhaust temperature has the most significant influence on the temperature in the regeneration equilibrium state, and the exhaust flow rate has the most significant impact on the pressure drop in the regeneration equilibrium state.

Nickel-rich Fe–Ni alloy nanoparticles with different compositions were prepared by solution reduction using hydrazine as reductant. The phase composition, morphologies and magnetic properties of as-prepared and annealed samples were characterized by an X-ray diffractionmeter (XRD), a scanning electron microscope (SEM) and a vibrating sample magnetometer (VSM), respectively. XRD results show that all the samples exhibit a single phase with face-centered cubic structure before and after annealing. SEM images show that the as-prepared spherical particles are composed of smaller crystallites. VSM results indicate that the saturation magnetization decreases obviously with the increase of nickel content, while it increases with the annealing temperature. In addition, the samples transform from a half hard magnetic behavior to a typical soft magnetic behavior with the increase of annealing temperature.

Tool wear is a problem in the turning of titanium alloy, and it is thus of great importance to understand and quantitatively predict tool wear and tool life. In this paper, a combined tool wear model including abrasive, adhesion, and diffusion wear has been implemented in a commercial finite element (FE) code to predict tool wear. Many key problems in tool wear simulation are presented and discussed such as temperature distribution, the updating of tool geometry, and the smoothing of wear boundary. Subsequently, a finite element method wear prediction model is built, and the results are compared with the experimental value; a good agreement was found. Simulated results showed that cutting force will decrease first and then increase with the increase of the concentration of hydrogen, while tool life varies in the opposite way; therefore, the optimum value of hydrogen content is about 0.3 %. The addition of 0.3 % hydrogen could improve tool life greatly, and its tool life is more than three times that of the as-received material. The hydrogenation process's favorable effect is limited by cutting parameters and cooling conditions. According to the numerical results, an appropriate machining speed and higher feed is the selection criterion for high-efficiency machining of hydrogenated titanium alloy. Furthermore, a reasonable range of cutting parameters is found; the cutting speed is in the range of 50–100 m/min, and the feed is in 0.15–0.25 mm/rev.

Graphite-coated Fe nanocapsules were prepared by arc discharge method. Fe nanocapsules have a core/shell microstructure, in which Fe nanoparticles as cores and graphite layers as shells. Compared with Fe nanoparticles with an oxide shell, the graphite shell can restrain the growth of Fe nanoparticles, which leads to lower saturation magnetization and higher natural resonance frequency. The Fe nanocapsules are stable securely below 220 °C in the air, due to the enhancement of thermal stability and the anti-oxidation by graphite layer shell. Dielectric relaxation of graphite shell and the interfacial relaxation between graphite shell and Fe core lead to the dual nonlinear dielectric resonance. Graphite shells can dramatically improve the magnetic/dielectric loss and the attenuation constant in the 2–18 GHz though the dual dielectric resonance and protection of Fe cores, leading to enhanced microwave absorption properties of Fe nanocapsules at 2–18 GHz.

We prepared NiZnCu ferrite powders with nominal composition Ni 0.4− x Zn 0.6 Cu x Fe 2 O 4 ( x =0–0.2) via chemical coprecipitation method with NaOH and Na 2 CO 3 as coprecipitators. The structural and magnetic properties of these compounds were studied and compared. It is found that all the specimens exhibit single-phase structure after annealing. The saturation magnetization of specimens with NaOH as coprecipitator is lower than that with Na 2 CO 3 as coprecipitator. It is also found that the growth of grains is hindered for specimens using Na 2 CO 3 as coprecipitator.

In this paper, the hydro-expanding principle for a double-layered tube is set out in detail. The force state of a double-layered tube was analyzed during the process of hydro-forming. The stress and strain for the inner and outer tubes were evaluated using theories of elasticity and plasticity. By using the relation of deformed compatibility of hoop strain, suitable conditions of hydraulic expansion and variable range of hydro-expanding pressure are given, and formulae of hydro-expanding pressure related to residual contact pressure are derived. The results are applicable to cases where the inner tube is both thin-walled and thick-walled.

This paper presents the design of ribbon wound pressure vessels useful for Ammonia, Urea and Methanol plants. The design is to create a thin shell of 1/5 the total wall thickness required, weld it to the end pieces, and wind 4 to 8 mm thick ribbons of 80 mm width at an angle of 15 to 30 degrees on the inner shell, using a prestress. The ribbons are welded at the ends and an even number of layers are wound cross-helically on to the shell. With more than 7000 vessels over the pressure range of 50 to 350 atmospheres in use in the various chemical industries in China over the past 30 years, their safety record has been excellent. Of particular interest has been the application of this technology in the Ammonia and Urea plants, where the design allows fabrication of these vessels at substantial reduction in cost, and early delivery, when compared to the mono wall technology.

In this paper, the authors propose a circumferential bursting pressure formula for pressure vessels that are made by being helically wound with steel ribbbon. They have analysed axial and circumferential strengths from the bursting pressure formulae in both directions. It is shown that the steel ribbon helically wound pressure vessel is quite safe both in the axial and circumferential directions, with the axial strength being a little higher than the circumferential one. It is also shown that this pressure vessel structure is an optimum, which has balanced circumferential and axial strengths comprehensively. Finally, the authors recommended the range of winding angle α appropriate for engineering.

In this work, a new type of TiO2/polymer solar cells was fabricated. The device structure was indium tin oxide titanium dioxide (TiO2)/ copper phthalocyanine (CuPc)/poly(3-hexylthiophene) (P3HT)/Au. In this architecture, TiO2 was designed to act as electron acceptor, and P3HT was electron donor. CuPc was used as a sensitizer to enhance photon absorption. The results show that by inserting CuPc between P3HT and TiO2 layers, the light absorption, excitons separation, and photocurrent under illumination are dramatically improved. The device has a short current density (JSC) of 1.15mA∕cm2 and power conversion efficiency (η) of 0.28% without CuPc layer. However, JSC and η turn to be 2.22mA∕cm2 and 0.66%, respectively, with a 20nm thickness CuPc layer under air mass 1.5 global (AM1.5G) illumination with the intensity of 100mW∕cm2. The performance improvement can be attributed to the higher carrier mobility and the stronger photon absorption using CuPc as a sensitizing layer.