Performance-driven routing tree construction with buffer insertion and wire sizing

A new approach was proposed to construct a performance-driven rectilinear Steiner tree with simultaneous buffer insertion and wiresizing optimization （PDRST/BW） under a higher order resistance-inductancecapacitance （RLC） delay model. This approach is based on the concept of sharing-buffer insertion and dynamic programming approach combined with a bottom-up rectilinear Steiner tree construction. The performances include the timing delay and the quality of signal waveform. The experimental results show that our proposed approach is scalable and obtains better performance than SP-tree and graph-RTBW approaches for the test signal nets.     

Automatic artist recognition of songs for advanced retrieval

Automatic recognition of artists is very important in acoustic music indexing, browsing, and contentbased acoustic music retrieving, but synchronously it is still a challenging errand to extract the most representative and salient attributes to depict diversiform artists. In this paper, we developed a novel system to complete the reorganization of artist automatically. The proposed system can efficiently identify the artist's voice of a raw song by analyzing substantive features extracted from both pure music and singing song mixed with accompanying music. The experiments on different genres of songs illustrate that the proposed system is possible.     

On-line modeling of non-stationary network traffic with schwarz information criterion

Modeling of network traffic is a fundamental building block of computer science. Measurements of network traffic demonstrate that self-similarity is one of the basic properties of the network traffic possess at large time-scale. This paper investigates the change of non-stationary self-similarity of network traffic over time,and proposes a method of combining the discrete wavelet transform (DWT) and Schwarz information criterion (SIC) to detect change points of self-similarity in network traffic. The traffi...     

Integrated fluid-thermal-structural numerical analysis for the quenching of metallic components

The quenching of a metal component with a channel section in a water tank is numerically simulated. Computational fluid dynamics (CFD) is used to model the multiphase flow and the heat transfer in film boiling, nucleate boiling and convective cooling processes to calculate the difference in heat transfer rate around the component and then combining with the thermal simulation and structure analysis of the component to study the effect of heat transfer rate on the distortion of the U-channel component. A model is also established to calculate the residual stress produced by quenching. The coupling fluid-thermal-structural simulation provides an insight into the deformation of the component and can be used to perform parameter analysis to reduce the distortion of the component.     

Vehicle trajectory challenge in predictive active steering rollover prevention

High center of mass vehicles are likely to rollover in extreme maneuvers. Available works present control strategies to prevent rollover. In these works, however, other important parameters such as path trajectory tracking are not a main concern. In this paper conflicts between rollover prevention and trajectory tracking is investigated. Model predictive control (MPC) is adopted to predict and avoid rollover while tracking desired trajectory. For this regard a model based future error estimation is introduced. The control framework predicts both rollover and trajectory error simultaneously. It avoids rollover while tries to track the trajectory. Simulation results for two controllers with and without trajectory tracking are presented. The results indicate that the controllers effectively limit rollover as a hard constraint while the trajectory tracking controller also minimizes and recovers the path error.     

Effect of operating parameters on diesel/propane dual fuel premixed compression ignition in a diesel engine

In this research, the effects of three operating parameters (Diesel injection timing, propane ratio, and exhaust gas recirculation (EGR) rates) in a diesel-propane dual fuel combustion were investigated. The characteristics of dual-fuel combustion were analyzed by engine parameters, such as emission levels (Nitrogen oxides (NO_x) and particulate matter (PM)), gross indicated thermal efficiency (GIE) and gross IMEP Coefficient of Variance (CoV). Based on the results, improving operating strategies of the four main operating points were conducted for dual-fuel PCCI combustion with restrictions on the emissions and the maximum pressure rise rate. The NOx emission was restricted to below 0.21 g/kWh in terms of the indicated specific NO_x (ISNO_x), PM was restricted to under 0.2 FSN, and the maximum pressure rise rate (MPRR) was restricted to 10 bar/deg. Dual-fuel PCI combustion can be available with low NO_x, PM emission and the maximum pressure rise rate in relatively low load condition. However, exceeding of PM and MPRR regulation was occurred in high load condition, therefore, design of optimal piston shape for early diesel injection and modification of hardware optimizing for dual-fuel combustion should be taken into consideration.     

Decoupled self-tuning PI controller for an idling stop system applied to scooters

This paper is aimed to propose a decoupled self-tuning proportional plus integral (PI) controller with simple law for an idling stop system applied to scooters. An integrated starter generator (ISG) of the idling stop system is designed with a high efficiency permanent magnet synchronous motor (PMSM). The PMSM used as an ISG must have a high torque characteristic to ensure that the engine can be accelerated up to firing speed. A conventional and useful control algorithm named PI control is unable to handle motor current very well for dynamic load, parametric variation, and external disturbance, especially in a vehicle application. Therefore, a robust algorithm for current control in an ISG is proposed. The decoupled selftuning PI controller based on the Lyapunov stability theorem is utilized to guarantee the control performance. Numerical simulations demonstrate the effectiveness of the proposed control algorithm. Experimental results show that the engine of a 150 cm3 scooter can be cranked to reach firing speed by a ISG within 0.1?0.2 second. The proposed method is simple, robust, as well as stable for idling stop system, and can be effectively implemented.     

Numerical study of the early injection parameters on wall wetting characteristics of an HCCI diesel engine using early injection strategy

Wall wetting in the early injection period has been proved to be unavoidable in the HCCI (Homogeneous charge compression ignition) diesel engine using early injection strategy, which directly affects in-cylinder fuel-air mixture formation. In this study, the effects of the early injection parameters (injection timing, injection angle and injection pressure) on wall wetting characteristics of an HCCI diesel engine using early injection strategy have been numerically investigated. The variations of maximum wall film mass, evaporated wall film mass and residual wall film mass have been summarized. The concept of MHI (Mixture Homogenous Index) is introduced to evaluate the homogeneity of fuel-air mixture in the wall wetting region. In additions, the effects of the early injection parameters on the HC (Hydrocarbon Compounds) and CO (Carbon Monoxide) emissions have also been discussed. Results showed that in order to decrease the HC and CO emission caused by wall wetting as low as possible, it was better to increase the injection pressure and to advance the injection timing. The most effective method was to narrow the injection angle, In addition, the impingement target should be considered for choosing the injection timing and injection angle, and the impingement target of the piston bowl lip was recommended due to the enhancement of the atomization and the higher surface temperature.     

SAW焊接型剖面预报的模糊逻辑系统开发(英文)

A fuzzy model was presented to predict the weldment shape profile of submerged arc welds(SAW) including the shape of heat affected zone(HAZ).The SAW bead-on-plates were welded by following a full factorial design matrix.The design matrix consisted of three levels of input welding process parameters.The welds were cross-sectioned and etched,and the zones were measured.A mapping technique was used to measure the various segments of the weld zones.These mapped zones were used to build a fuzzy logic model.The membership functions of the fuzzy model were chosen for the accurate prediction of the weld zone.The fuzzy model was further tested for a set of test case data.The weld zone predicted by the fuzzy logic model was compared with the experimentally obtained shape profiles and close agreement between the two was noted.The mapping technique developed for the weld zones and the fuzzy logic model can be used for on-line control of the SAW process.From the SAW fuzzy logic model an estimation of the fusion and HAZ can also be developed.     

The effects of free surface and end cell on flow around a finite circular cylinder with low aspect ratio

Vortex-induced motion is an oscillatory phenomenon which occurs to a floating body with low aspect ratio. The basic phenomenological study about the effects of free surface and end cell on flow around a finite fixed circular cylinder was investigated in this study using particle image velocimetry and hydrodynamic force measurement. It was found from the former experiment that the wake of the cylinder is influenced by the both end cell and free surface. Blowup and back flow are generated from the end cell, and their effects are suspended by free surface. The result of hydrodynamic force measurement showed the effect of Reynolds number, Froude number, and the aspect ratio of the floating body on the hydrodynamic force. Fluctuating components of hydrodynamic coefficients decrease for increasing Reynolds number, Froude number, and the aspect ratio. On the other hand, the mean drag coefficient increases as Froude number increases and decreases as the aspect ratio increases. The interpretation to these results was discussed in comparison with flow structures observed in the experiment. In addition, it was found that the effect of Reynolds number on the mean drag coefficient changes at different aspect ratios. A possible interpretation to this phenomenon was proposed.