The vibrating string pressure sensor is designed according to the working surroundings and conditions. this sensor is used for the weighing of the fixed-quantity bucket loader in the main shaft lifting systems of coal...The vibrating string pressure sensor is designed according to the working surroundings and conditions. this sensor is used for the weighing of the fixed-quantity bucket loader in the main shaft lifting systems of coal mines. The design of the sensor has been introduced in detail. Calibrations and errors of the sensor theoretical fornada have also been analyzed.展开更多
In order to overcome the deficiencies of traditional pressure sensors, a kind of intelligent pressure sensors with temperature correction is designed. Qccording to the intelligent sensor system of composition and rang...In order to overcome the deficiencies of traditional pressure sensors, a kind of intelligent pressure sensors with temperature correction is designed. Qccording to the intelligent sensor system of composition and range of applications, with fully taking into account the parameters of the connection between of co-ordination, we chose a good usability, high reliability and low cost components composed of the entire measurement system, with controlling and dealing with in 80C51 miller, the system had the temperature and pressure parameters with automatic measurement, amplification, A/D conversion, the weak signal locked amplification, as well as PhaseSensitive Detection （PSD）, common-mode signal rejection, the collected signal de-noising processing, cross-sensitivity of the decoupling and show the results. It also has a self-test, automatic temperature condition and on, site communications and other functions.展开更多
The most complicated component in cavitating flow and pressure distribution is the flow in the cavity closure line. The cavitating flow and pressure distribution provide critical aspects of flow field details in the r...The most complicated component in cavitating flow and pressure distribution is the flow in the cavity closure line. The cavitating flow and pressure distribution provide critical aspects of flow field details in the region. The integral of pressure results of the hydrodynamic forces, indicate domination in the design of a supercavitating vehicle. An experiment was performed in a water tunnel to investigate the pressure characteristics of the cavity closure region. Ventilation methods were employed to generate artificial cavity, and the ventilation rate was adjusted accordingly to obtain the desired cavity length. An array of pressure transducers was laid down the cavity closure line to capture pressure distribution in this region. The experimental results show that there is a pressure peak in the cavity closure region, and the rise rate of pressure in space tends to be higher in the upwind side when the flow is non-axisymmetric. The transient pressure variations during the cavity formation procedure were also present. The method of measurement in this paper can be referenced by engineers. The result helps to study the flow pattern of cavity closure region, and it can also be used to analyze the formation of supercavitating vehicle hydrodynamics.展开更多
This paper describes a research project that uses embedded systems design principles to construct and simulate an Engine Control Unit （ECU） for a hybrid car. The ECU is designed to select a fuel type based on the st...This paper describes a research project that uses embedded systems design principles to construct and simulate an Engine Control Unit （ECU） for a hybrid car. The ECU is designed to select a fuel type based on the stress level of the simulated engine. The primary goal of the project was to use a robotics kit, connected to sensors, to simulate a hybrid car under certain stress conditions such as hill climbing or full throttle. The project uses the LEGO~ Mindstorms~ NXT robotics kit combined with a Java-based firmware, a pressure sensor to simulate a gas pedal, and a tilt sensor to determine when the car is traveling uphill or downhill. The objective was to develop, through simulation, a framework for adjusting the ratios/proportions of fuel types and mixture under the stress conditions. The expected result was to establish a basis for determining the ideal/optimal fuel-mix-stress ratios on the hybrid car＇s performance. Using the NXT robotics kit abstracted the low level details of the embedded system design, which allowed a focus on the high level design details of the research. Also, using the NXJ Java-based firmware allowed the incorporation of object oriented design principles into the project. The paper outlines the evolution and the compromises made in the choice of hardware and software components, and describes the computations and methodologies used in the project.展开更多
An experimental investigation on the unsteady tip flow field of a transonic compressor rotor has been performed.The casing-mounted high frequency response pressure transducers were arranged along both the blade chord ...An experimental investigation on the unsteady tip flow field of a transonic compressor rotor has been performed.The casing-mounted high frequency response pressure transducers were arranged along both the blade chord and the blade pitch.The chord-wise ones were used to indicate both the ensemble averaged and time varying flow structure of the tip region of the rotor at different operating points under 95% design speed and 60% design speed.The pitch-wise circumferential transducers were mainly used to analyze the unsteadiness frequency of the tip leakage flow in the rotor frame at the near stall condition.The contours of casing wall pressure show that there were two clear low pressure regions in blade passages,one along the chord direction,caused by the leakage flow and the other along the tangential direction,maybe caused by the forward swept leading edge.Both low pressure regions were originated from the leading edge and formed a scissor-like flow pattern.At 95% design speed condition,the shock wave interacted with the low pressure region and made the flow field unsteady.With the mass flow reduced,the two low pressure regions gradually contracted to the leading edge and then a spike disturbance emerged.展开更多
This paper proposes the design and research on the high bandwidth linear frequency sweep signal source involved in the readout unit module of the wireless passive pressure sensor in high temperature based on the princ...This paper proposes the design and research on the high bandwidth linear frequency sweep signal source involved in the readout unit module of the wireless passive pressure sensor in high temperature based on the principle of mutual inductance coupling which is applied widely at present. The operating principle of the linear sweep frequency source based on the direct digital frequency synthesis （DDS） technology is introduced, and the implementation method of the hardware circuit and logic sequential control process required in our system has been realized utilizing this technology. Through the experiments under different conditions of the step value, the sweep range and other related design indicators, the influence on the extraction method of resonance frequency information, extraction accuracy, and others during the readout system of the mutual inductance coupling sensor are analyzed and studied. The design of the linear frequency sweep signal source is realized with a resonance frequency change resolution of 6 kHz, a minimum step value of 1 kHz, and a precision of frequency for 0.116 Hz within the sweep width of 1 MHz - 100MHz. Due to the use of the integrated commercial chip, the linear sweep frequency source is made small in size, high working frequency, high resolution and low step values for the readout unit modularized of a higher application value.展开更多
文摘The vibrating string pressure sensor is designed according to the working surroundings and conditions. this sensor is used for the weighing of the fixed-quantity bucket loader in the main shaft lifting systems of coal mines. The design of the sensor has been introduced in detail. Calibrations and errors of the sensor theoretical fornada have also been analyzed.
文摘In order to overcome the deficiencies of traditional pressure sensors, a kind of intelligent pressure sensors with temperature correction is designed. Qccording to the intelligent sensor system of composition and range of applications, with fully taking into account the parameters of the connection between of co-ordination, we chose a good usability, high reliability and low cost components composed of the entire measurement system, with controlling and dealing with in 80C51 miller, the system had the temperature and pressure parameters with automatic measurement, amplification, A/D conversion, the weak signal locked amplification, as well as PhaseSensitive Detection （PSD）, common-mode signal rejection, the collected signal de-noising processing, cross-sensitivity of the decoupling and show the results. It also has a self-test, automatic temperature condition and on, site communications and other functions.
基金Foundation item： Supported by the National Natural Science Foundation of China （11172241）, and Northwestern Polytechnical University Foundation for Fundamental Research. （NPU-FFR- 1015）
文摘The most complicated component in cavitating flow and pressure distribution is the flow in the cavity closure line. The cavitating flow and pressure distribution provide critical aspects of flow field details in the region. The integral of pressure results of the hydrodynamic forces, indicate domination in the design of a supercavitating vehicle. An experiment was performed in a water tunnel to investigate the pressure characteristics of the cavity closure region. Ventilation methods were employed to generate artificial cavity, and the ventilation rate was adjusted accordingly to obtain the desired cavity length. An array of pressure transducers was laid down the cavity closure line to capture pressure distribution in this region. The experimental results show that there is a pressure peak in the cavity closure region, and the rise rate of pressure in space tends to be higher in the upwind side when the flow is non-axisymmetric. The transient pressure variations during the cavity formation procedure were also present. The method of measurement in this paper can be referenced by engineers. The result helps to study the flow pattern of cavity closure region, and it can also be used to analyze the formation of supercavitating vehicle hydrodynamics.
文摘This paper describes a research project that uses embedded systems design principles to construct and simulate an Engine Control Unit （ECU） for a hybrid car. The ECU is designed to select a fuel type based on the stress level of the simulated engine. The primary goal of the project was to use a robotics kit, connected to sensors, to simulate a hybrid car under certain stress conditions such as hill climbing or full throttle. The project uses the LEGO~ Mindstorms~ NXT robotics kit combined with a Java-based firmware, a pressure sensor to simulate a gas pedal, and a tilt sensor to determine when the car is traveling uphill or downhill. The objective was to develop, through simulation, a framework for adjusting the ratios/proportions of fuel types and mixture under the stress conditions. The expected result was to establish a basis for determining the ideal/optimal fuel-mix-stress ratios on the hybrid car＇s performance. Using the NXT robotics kit abstracted the low level details of the embedded system design, which allowed a focus on the high level design details of the research. Also, using the NXJ Java-based firmware allowed the incorporation of object oriented design principles into the project. The paper outlines the evolution and the compromises made in the choice of hardware and software components, and describes the computations and methodologies used in the project.
基金supported by the National Natural Science Foundation in China under Grant No.50736007National Basic Research Program 2007CB210104 of China
文摘An experimental investigation on the unsteady tip flow field of a transonic compressor rotor has been performed.The casing-mounted high frequency response pressure transducers were arranged along both the blade chord and the blade pitch.The chord-wise ones were used to indicate both the ensemble averaged and time varying flow structure of the tip region of the rotor at different operating points under 95% design speed and 60% design speed.The pitch-wise circumferential transducers were mainly used to analyze the unsteadiness frequency of the tip leakage flow in the rotor frame at the near stall condition.The contours of casing wall pressure show that there were two clear low pressure regions in blade passages,one along the chord direction,caused by the leakage flow and the other along the tangential direction,maybe caused by the forward swept leading edge.Both low pressure regions were originated from the leading edge and formed a scissor-like flow pattern.At 95% design speed condition,the shock wave interacted with the low pressure region and made the flow field unsteady.With the mass flow reduced,the two low pressure regions gradually contracted to the leading edge and then a spike disturbance emerged.
文摘This paper proposes the design and research on the high bandwidth linear frequency sweep signal source involved in the readout unit module of the wireless passive pressure sensor in high temperature based on the principle of mutual inductance coupling which is applied widely at present. The operating principle of the linear sweep frequency source based on the direct digital frequency synthesis （DDS） technology is introduced, and the implementation method of the hardware circuit and logic sequential control process required in our system has been realized utilizing this technology. Through the experiments under different conditions of the step value, the sweep range and other related design indicators, the influence on the extraction method of resonance frequency information, extraction accuracy, and others during the readout system of the mutual inductance coupling sensor are analyzed and studied. The design of the linear frequency sweep signal source is realized with a resonance frequency change resolution of 6 kHz, a minimum step value of 1 kHz, and a precision of frequency for 0.116 Hz within the sweep width of 1 MHz - 100MHz. Due to the use of the integrated commercial chip, the linear sweep frequency source is made small in size, high working frequency, high resolution and low step values for the readout unit modularized of a higher application value.
