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In this paper we are concerned with the multiplicity of solutions near resonance for the following nonlinear equation: −Δu = λu + f(x,u) associated with the Dirichlet boundary condition, where f satisfies some appropriate conditions. We will treat this problem in the framework of dynamical systems. It will be shown that there exist a one-sided neighborhood Λ− of the eigenvalue μk of the Laplacian operator and a dense subset D of R such that the equation has at least four distinct nontrivial solutions generically for λ ∈ Λ− ∩D. [ABSTRACT FROM AUTHOR]

In this paper we first give a criterion on stability of equilibrium solutions for autonomous systems with constraints. Then we discuss the relationship between asymptotic behaviors of an asymptotically autonomous system with constraint and its limit system. Finally as an example, we revisit an extreme ideology model proposed in the literature and give a more detailed description on the dynamics of the system. [ABSTRACT FROM AUTHOR]

In this study, the crankcase gas temperature, flow rate, gaseous emissions (NOx, CO and HC) and particle emissions (particle size distribution, number and mass concentration, geometric mean diameter) compared with tailpipe are investigated in a light-duty common rail diesel engine. It is shown that the emissions from the crankcase are mainly affected by the second in-cylinder pressure peak. The crankcase gas temperature varies between 52 °C and 68 °C, and the crankcase gas flow rate slightly increases with load and speed but does not vary much with injection timing. The CO emission from crankcase is about 2%−5% of that from tailpipe, the NOx emissions are only about 1% and the HC emissions are more than 10%. The blow-by gas percentage is 10−8 order and reduces with heavier engine load and faster engine speed. The blow-by HC emission percentage varies from 5% to 35%. As engine load is increased and engine speed is decreased, the nuclei mode particles of crankcase reduce and the accumulation mode particles increase. Furthermore, the particle total number concentration increases with load but decreases with speed and retarding injection timing. The total mass concentration increases with load but rises and falls with speed and injection timing. The crankcase particle geometric mean diameter based on mass is nearly twice larger than that of tailpipe, while the ones based on number are rarely different except the higher load. [ABSTRACT FROM AUTHOR]

In this study, the experiment is conducted on a four-cylinder direct-injection diesel engine equipped with a turbocharger and a high-pressure common rail injection system. The test fuels include diesel from direct coal liquefaction, diesel and their blends. The effects of exhaust gas recirculation and retarded injection on the combustion, the nitrogen oxide emissions and the soot emissions under low-temperature combustion are explored. The results indicate that exhaust gas recirculation and retarded injection can effectively lengthen the ignition delay of test fuels especially for diesel from direct coal liquefaction. The ignition delays of all the fuels become shorter with increasing engine load, but the variation rates for diesel from direct coal liquefaction and diesel are not the same. Retarded injection can lead to a soot hump for the four fuels, but it reflects this soot change for diesel from direct coal liquefaction more sensitively than for diesel. Diesel from direct coal liquefaction produces lower nitrogen oxide emissions and lower soot emissions than diesel does under low-temperature combustion. A control strategy that achieves reduction in both the nitrogen oxide emissions and the soot emissions will cause the fuel consumption to deteriorate. [ABSTRACT FROM PUBLISHER]

Bismuth ferrite (BiFeO 3) holds great potentials in the photoelectrocatalysis due to the advantages of low cost, narrow band gap and good chemical stability. However, the photoelectrochemical performance of BiFeO 3 is usually inhibited by the poor charge carrier transport. Here, we report the flame annealing synthesized Sm3+ doped BiFeO 3 photocathodes for efficient hydrogen production. Greatly enhanced water reduction activity was found in doped samples. The Bi 0.95 Sm 0.05 FeO 3 composition exhibited largest photocurrent density of 0.1061 mA cm−2 at 0 V vs. RHE in 0.5 M Na 2 SO 4 , which was 5.6 times higher than that of the pristine BiFeO 3. Mott-Schottky analysis and electrochemical impedance spectra proved that the Bi3+substitution increased the charge carrier concentration and facilitated the charge migration. Incident photon-to-electron conversion efficiency (IPCE) value for Bi 0.95 Sm 0.05 FeO 3 film (∼6.39% at 325 nm) was approximately ten times higher than that of undoped sample. The high performance can be ascribed to the rational Sm3+ doping, which can improve visible light absorption ability, facilitate the charge carrier transport kinetics and hinder the recombination of photogenerated carriers. Our work provides a facile cation doping with rare earth ions to improve the photoelectrochemical performances. [ABSTRACT FROM AUTHOR]

The purpose of this study is to compare the combustion and exhaust emissions of a four-stroke diesel engine with supercharging and a high-pressure common-rail injection system fuelled with diesel from direct coal liquefaction, with diesel and with their blends. The operating conditions are set at an engine speed of 1450 r/min, an engine torque of 112 N m (low load; a brake mean effective pressure of 0.2964 MPa) and an engine torque of 224 N m (medium load; a brake mean effective pressure of 0.5928 MPa). The injection pressure is set at 1000 bar, and the injection timing is set at 2.5° crank angle after top dead centre and 3.5° crank angle after top dead centre for the low load and the medium load respectively. The experimental results show that, for the two loads, the phases of the peak pressure and the maximum heat release rate are retarded on increasing the proportion of diesel from direct coal liquefaction; meanwhile, the ignition delay increases significantly, and the combustion duration decreases obviously. The nitrogen oxide and soot emissions decrease simultaneously and the carbon monoxide and hydrocarbon emissions increase significantly on increasing amount of diesel from direct coal liquefaction. The trade-off relationship between nitrogen oxide emissions and soot emissions can be improved when the diesel engine is fuelled with diesel from direct coal liquefaction instead of with diesel. An artificial neural network is used to predict accurately the exhaust emissions (nitrogen oxide, soot, carbon monoxide and hydrocarbon) and the fuel consumption of the blend containing 50% diesel and 50% diesel from direct coal liquefaction over the European Stationary Cycle. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the performance and exhaust emissions of diesel engine fueled with diesel from direct coal liquefaction (DDCL)–biodiesel blends consisting of 0%, 20% and 40% biodiesel are investigated. In order to decrease nitric oxides (NOX) and soot emissions, retarded injection and cooled exhaust gas recirculation (EGR) strategies are introduced. Experiments are conducted on a four-cylinder, four-stroke, direct injected diesel engine without any modification. It is found that compared with pure DDCL, DDCL–biodiesel blends can reduce maximum pressure rise rate and gain lower combustion noise and mechanical load of diesel engine. In addition, there is hardly any difference for combustion phase between test fuels. Both exhaust emissions and fuel consumption are reduced due to the improved combustion by fuel properties of biodiesel, such as cetane number and fuel oxygen. When EGR rate is increased to 40%, with an increment of biodiesel in blends, NOX, carbon monoxide (CO) and equivalent brake specific fuel consumption (BSFC) are still decreased, and soot emission is increased. Anyway, both exhaust emissions and equivalent fuel consumption are controlled to a quite low level under retarded injection for DDCL–biodiesel blends. [Copyright &y& Elsevier]