In Steer Release condition, due to the ability of actual vehicle to resist external small perturbations and self-Adaptive coordination can't be described in the previous vehicle model, the stability of vehicle is ...
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Based on the application of self-developed electro-hydraulic variable valve train (VVT), controlled Auto-Ignition(CAI) was achieved with Negative Valve Overlap (NVO) strategy. This VVT system that replaced the origina...
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Based on the application of self-developed electro-hydraulic variable valve train (VVT), controlled Auto-Ignition(CAI) was achieved with Negative Valve Overlap (NVO) strategy. This VVT system that replaced the original camshaft was mounted on the head of a modified single cylinder engine. The cycle-to-cycle variation of CAI Combustion was investigated under several different operating points with 100 consecutive cycles sampled and stored. The experimental results indicated that as the excess air coefficient increases, with fixed engine speed and valve event, the coefficient of variation of indicated mean effective pressure (CoV IMEP ) dropped firstly and then increased. The CoV IMEP had the minimum value when the excess air coefficient ranges from 1.1 to 1.3. The engine speed and the valve lift showed the potential to influence CoV IMEP . Increased engine speed led to a more intense mixing progress, which introduced high intensity turbulence into the cylinder and resulted in a higher level of charge homogeneity at the end of compression stroke, and finally a steady CAI combustion. Meanwhile, decreasing the valve lift had a relatively minor effect. The variation of IMEP was consequently suppressed to some extend.
Large-scale natural or man-made disasters have the potential to cause great loss of life, human injury and extreme property damage. Evacuation from areas at risk is often one of the most feasible strategies that can b...
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This paper presents a parallel algorithm for realtime simulation of the electromagnetic transient dynamics of the integrated power systems, which contains multi-phase machines and converters. The proposed algorithm is...
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This paper presents a parallel algorithm for realtime simulation of the electromagnetic transient dynamics of the integrated power systems, which contains multi-phase machines and converters. The proposed algorithm is base on the component partitioning and Multiarea Thevenin Equivalent (MATE) methods. By partitioning the computational model of the multi-phase machine into several parts, a decomposition and coordination computation schema is designed. Moreover, with the help of the component partitioning, the overall system can be partitioned more flexibly and balanced, which helps to enhance the efficiency of the MATE methods eventually. Base on the proposed algorithm, a parallel simulation platform is constructed on a multi-core computer using OpenMP programs. Test results of a typical Integrated Power System (IPS) on ships verify the accuracy and efficiency of the proposed algorithm as well as prove the feasibility of applying the multi-core techniques to realize high performance power system simulations.
The electromagnetic transient simulation of power system with many switching events is very time-consuming due to the huge increment of computation caused by frequent changing system topologies. To speedup the paralle...
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The electromagnetic transient simulation of power system with many switching events is very time-consuming due to the huge increment of computation caused by frequent changing system topologies. To speedup the parallel simulations of the power systems with switch events, a novel algorithm based on the Multi Area Thevenin Equivalent (MATE) and the flexible half-step interpolation method is proposed. Through runtime caching of the matrixes corresponding to the topology changes, the repeated matrix operations are eliminated for both the subsystem and coordinator sides, while the communication costs for the parallel simulations are also reduced significantly. Moreover, a parallel simulation platform is developed based on the multi-core computation environment and MPI functions. On this platform, the accuracy and efficiency of the proposed algorithm are verified by the real-time simulations of a power system containing four 3-phase rectifiers and three 5-phase PWM inverters.
Urban Development Zones are always constructed rapidly and intensively, resulting in contingent ecological and environmental problems. This paper establishes a set of ecological-security index system for urban develop...
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Urban Development Zones are always constructed rapidly and intensively, resulting in contingent ecological and environmental problems. This paper establishes a set of ecological-security index system for urban development and construction. It utilizes Pressure-state-Response (P-S-R) model to select frequently-used indexes, which represent the features of urban society, economy, and ecosystem environment. Through public survey and the analysis of the questionnaires, and Analytic Hierarchy Process (A-H-P) analysis, it prioritizes all the indices and screens out a set of operational eco-security index system according to the principle of monitorability. This method is applied to establish the eco-security monitoring index system for Beijing Eco-Tech Development Zone, therefore to provide basis for dynamic eco-security monitoring for the development and construction of Beijing Eco-Tech Zone.
In this paper, we tested the GW 2.4S automobile engine and Mltsublshi2.4S automobile engine by adopting sound intensity method. During the experiment we got the spectrum graph, and by matching the spectrum peak from t...
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In this paper, we tested the GW 2.4S automobile engine and Mltsublshi2.4S automobile engine by adopting sound intensity method. During the experiment we got the spectrum graph, and by matching the spectrum peak from the spectrum graph and spectrum peak from the total engine noise to conclude the main noise source. By comparing Peak of the low frequency and the high frequency at the different measuring surface of the engine, we can speculate the engine's noise source, and then we can get different types of engine's noise source at the different frequency. After that, these two engines' noise source is estimated by using the sound power from the each side of these two engines. Mechanical noise and combustion noise also can be separated preliminary.
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