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An improved multi-dimensional CFD code has been employed to simulate the spray, combustion and pollution formation process within a diesel engine cylinder. The computational results are compared with experimental data from an opti...
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An improved multi-dimensional CFD code has been employed to simulate the spray, combustion and pollution formation process within a diesel engine cylinder. The computational results are compared with experimental data from an optical high-speed research engine equipped with a high-pressure injection system. Several spray sub-models have been implemented into the code, and their influence on the predicted droplet characteristic was evaluated. These models account for liquid core atomization, droplet secondary breakup, spray/wall interaction, droplet turbulent dispersion and evaporation. These models improve the prediction of the droplet sizes within a diesel spray and provides a more accurate initial condition for the evaporation, combustion models. The combustion submodel employed has two components: one for predicting auto-ignition and one for computing the subsequent combustion of the ignited gas. Thermal NOx formation is calculated according to the extended Zeldovich mechanism, which gives the NOx formation as a function of temperature and O, H and OH radical concentrations. Soot formation process adopted in present study is modeled according to a hybrid chemical kinetics/turbulent mixing controlled rate expression. For the engine configurations and operating conditions considered, in most case the calculated cylinder averaged results show good agreement between measured and global pressure, heat release rate and emission data, but in some case they have limitations. Discrepancies are highlighted and possible reasons suggested. The major influences of the injection timing and combustion chamber geometry on the pollutant formation processes have been identified. The calculated results provide a detailed insight into the processes governing combustion and pollutant formation in spray flames under diesel engine conditions. The good agreement indicates that computer models are available for use by the engine industry to provide directions for engine design.
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The road sign is an important facility which manages the road traffic safety and eases the road traffic congestion. This paper proposes a Semantically-enabled System for Road Sign Management (SeRSM). The SeRSM system is built base...
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The road sign is an important facility which manages the road traffic safety and eases the road traffic congestion. This paper proposes a Semantically-enabled System for Road Sign Management (SeRSM). The SeRSM system is built based on LarKC, which is a platform for scalable semantic data processing. In the SeRSM system, the users can select the corresponding operations through the interface integrated with a map service. These operations are sent to Jetty server for corresponding processing. They include sending some SPARQL query to invoke the corresponding workflow in the LarKC platform and to retrieve and reason the massive data stored in the data layer of LarKC and to return the result to the Jetty server. The paper made a full description of technical points such as the design objective, data sources, data integration, noisy data processing, detection of road consistency effectiveness. It also describes the system's user interface and basic functions in the end. The SeRSM has great value and social significance for improving traffic efficiency and traffic safety through successful applications in Zhenjiang and Yiwu in China.
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摘要 :
The road sign is an important facility which manages the road traffic safety and eases the road traffic congestion. This paper proposes a Semantically-enabled System for Road Sign Management (SeRSM). The SeRSM system is built base...
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The road sign is an important facility which manages the road traffic safety and eases the road traffic congestion. This paper proposes a Semantically-enabled System for Road Sign Management (SeRSM). The SeRSM system is built based on LarKC, which is a platform for scalable semantic data processing. In the SeRSM system, the users can select the corresponding operations through the interface integrated with a map service. These operations are sent to Jetty server for corresponding processing. They include sending some SPARQL query to invoke the corresponding workflow in the LarKC platform and to retrieve and reason the massive data stored in the data layer of LarKC and to return the result to the Jetty server. The paper made a full description of technical points such as the design objective, data sources, data integration, noisy data processing, detection of road consistency effectiveness. It also describes the system's user interface and basic functions in the end. The SeRSM has great value and social significance for improving traffic efficiency and traffic safety through successful applications in Zhenjiang and Yiwu in China.
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摘要 :
The road sign is an important facility which manages the road traffic safety and eases the road traffic congestion. This paper proposes a Semantically-enabled System for Road Sign Management (SeRSM). The SeRSM system is built base...
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The road sign is an important facility which manages the road traffic safety and eases the road traffic congestion. This paper proposes a Semantically-enabled System for Road Sign Management (SeRSM). The SeRSM system is built based on LarKC, which is a platform for scalable semantic data processing. In the SeRSM system, the users can select the corresponding operations through the interface integrated with a map service. These operations are sent to Jetty server for corresponding processing. They include sending some SPARQL query to invoke the corresponding workflow in the LarKC platform and to retrieve and reason the massive data stored in the data layer of LarKC and to return the result to the Jetty server. The paper made a full description of technical points such as the design objective, data sources, data integration, noisy data processing, detection of road consistency effectiveness. It also describes the system's user interface and basic functions in the end. The SeRSM has great value and social significance for improving traffic efficiency and traffic safety through successful applications in Zhenjiang and Yiwu in China.
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In the popular copper smelting process, top blowing and side blowing practices went into industrial production in the 70s and 80s. During 1991 a pilot test using a bottom blowing copper process was performed in China and several t...
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In the popular copper smelting process, top blowing and side blowing practices went into industrial production in the 70s and 80s. During 1991 a pilot test using a bottom blowing copper process was performed in China and several techno-economic indicators were obtained during this test. The bottom blowing copper smelting process wasn't put into industrial production until 2008. It has now more than 5 years of operation. The bottom blowing process has some advantages such as autogenously smelting without the addition of carbon, a high smelting rate, lower energy consumption, safe production and good environmental protection, etc. It was welcomed by the copper smelting industry. Now, seven companies have adopted this new copper smelting technique and put it into production, and five other companies are establishing the process. This paper discusses and illustrates the superiority and the features of the bottom blowing copper smelting process. The flow behaviors of the melt will be illustrated, which is important to study in order to promote the bottom blowing copper smelting process.
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The technical background on the development of super high-rise architectural water supply and drainage is explained, the goal of control the noise from water supply and drainage is defined, and how the noise comes from is analyzed...
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The technical background on the development of super high-rise architectural water supply and drainage is explained, the goal of control the noise from water supply and drainage is defined, and how the noise comes from is analyzed in this paper.This paper also put forward the control countermeasures and solutions.
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The technical background on the development of super high-rise architectural water supply and drainage is explained, the goal of control the noise from water supply and drainage is defined, and how the noise comes from is analyzed...
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The technical background on the development of super high-rise architectural water supply and drainage is explained, the goal of control the noise from water supply and drainage is defined, and how the noise comes from is analyzed in this paper.This paper also put forward the control countermeasures and solutions.
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Junggar basin in west China is rich in oil and gas reserves in different geological structures that range in depth from 800 m to 7000 m. A variety of cement slurries is used to ensure the cement integrity in the wells. For instanc...
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Junggar basin in west China is rich in oil and gas reserves in different geological structures that range in depth from 800 m to 7000 m. A variety of cement slurries is used to ensure the cement integrity in the wells. For instance, low-density cement as light as 1.1 g/cm3 with hollow glass microspheres has been used for low-pressure-gradient formations in long openhole wellbores, whereas high-density cement as heavy as 2.5 g/cm3 with iron mineral powder and other additives has been applied in high-pressure deep wells. This variety poses challenges to performing cement evaluation with traditional acoustic techniques that have limitations in providing unambiguous answers, and in some instances it is not possible to assess implications to zonal isolation behind casing. A new-generation ultrasonic imaging tool was deployed to increase the confidence in cement evaluation in Xinjiang oil field over the past 2 years. This technique combines the traditional pulse-echo ultrasonic measurement with a new flexural wave measurement. The analysis allows a better discrimination of solid, liquid and gas for density-independent cement evaluation behind casing, additional information on casing centering, annulus geometry, and accurate casing inspection at high resolution in one logging trip. Based on this improved zonal isolation information, well testing design improved, and the testing success rate was significantly increased over previous operations. Moreover, the cementing technique improved from proper post evaluation. The examples in this paper demonstrate the value of the high-quality logging data that were acquired in different downhole conditions. This paper presents a new way to look at cement quality and placement.
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Knocking is the main obstacle of increasing compression ratio to improve the thermal efficiency of gasoline engines. In this paper, the concept of stratified stoichiometric mixture (SSM) was proposed to suppress knocking in gasoli...
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Knocking is the main obstacle of increasing compression ratio to improve the thermal efficiency of gasoline engines. In this paper, the concept of stratified stoichiometric mixture (SSM) was proposed to suppress knocking in gasoline engines. The rich mixture near the spark plug increases the speed of the flame propagation and the lean mixture in the end gas suppresses the auto ignition. The overall air/fuel ratio keeps stoichiometric to solve the emission problem using three way catalysts (TWC). Moreover, both the rich zone and lean zone lead to soot free combustion due to homogeneous mixture. The effect on the knocking of homogeneous and stratified mixture was studied in a direct injection spark ignition (DISI) engine using numerical simulation and experimental investigation respectively. The results show that SSM formed by the two-stage injection can suppress knocking significantly, and the knocking intensity decreases gradually as the second fuel mass increasing or the second injection timing retarding; the combustion rate increases and the combustion phase advances when the rich zone of the stratified mixture becomes homogeneous, while the combustion rate decreases, the combustion phase retards, the peak pressure and the pressure rise rate decreases when the rich zone of the stratified mixture is inhomogeneous. The stratified combustion with overall stoichiometric mixture increases the CO emission and depresses the NOx emission, and the emissions can be effectively cleaned by TWC. The two-stage injection leads to soot formation due to the diffused combustion and the over-rich combustion, while Two-Zone Homogeneous Charge may be an ideal concept to avoid it. Compared with conventional methods of knocking suppress, the stratified combustion with stoichiometric mixture can keep the power output in contrast with retarding the spark timing, and can improve fuel economy than the enriched mixture.
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摘要 :
Knocking is the main obstacle of increasing compression ratio to improve the thermal efficiency of gasoline engines. In this paper, the concept of stratified stoichiometric mixture (SSM) was proposed to suppress knocking in gasoli...
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Knocking is the main obstacle of increasing compression ratio to improve the thermal efficiency of gasoline engines. In this paper, the concept of stratified stoichiometric mixture (SSM) was proposed to suppress knocking in gasoline engines. The rich mixture near the spark plug increases the speed of the flame propagation and the lean mixture in the end gas suppresses the auto ignition. The overall air/fuel ratio keeps stoichiometric to solve the emission problem using three way catalysts (TWC). Moreover, both the rich zone and lean zone lead to soot free combustion due to homogeneous mixture. The effect on the knocking of homogeneous and stratified mixture was studied in a direct injection spark ignition (DISI) engine using numerical simulation and experimental investigation respectively. The results show that SSM formed by the two-stage injection can suppress knocking significantly, and the knocking intensity decreases gradually as the second fuel mass increasing or the second injection timing retarding; the combustion rate increases and the combustion phase advances when the rich zone of the stratified mixture becomes homogeneous, while the combustion rate decreases, the combustion phase retards, the peak pressure and the pressure rise rate decreases when the rich zone of the stratified mixture is inhomogeneous. The stratified combustion with overall stoichiometric mixture increases the CO emission and depresses the NOx emission, and the emissions can be effectively cleaned by TWC. The two-stage injection leads to soot formation due to the diffused combustion and the over-rich combustion, while Two-Zone Homogeneous Charge may be an ideal concept to avoid it. Compared with conventional methods of knocking suppress, the stratified combustion with stoichiometric mixture can keep the power output in contrast with retarding the spark timing, and can improve fuel economy than the enriched mixture.
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