Nanjing, China
Nanjing, China

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Xu L.,Nanjing University of Aeronautics and Astronautics | Jiang Y.L.,29 Yudao St
Advanced Materials Research | Year: 2014

As a result of the strict restrictions on the use of power supply under the mine disaster, the Open loop cycle CO2 refrigeration system is used in the Mine Rescue Cabin. Traditional system has got a couple of equipment malfunctions frequently, such as the Ice-block in Cold-start, Cold-frost and Overheating. In this paper, a new type of refrigeration system is designed after the Thermodynamic analysis of extreme limit condition. The new system avoids the Ice-block and the cold-frost by limit the refrigerant flow, it also can improve the capability of the evaporator. It has a important reference value to the research and application of the open loop cycle CO2 refrigeration system in the extreme condition. © (2014) Trans Tech Publications, Switzerland.

Zhang P.Z.,29 Yudao St | Mao J.G.,29 Yudao St | Wang H.Q.,29 Yudao St | Liang X.,29 Yudao St | And 2 more authors.
Applied Mechanics and Materials | Year: 2014

In this paper, knock detection and analysis methods of the gasoline engine are applied to a modified kerosene engine. Two kinds of signals, the cylinder pressure signal and the vibration signal, are acquired by a pressure sensor mounted in a spark plug and an accelerometer mounted on the cylinder block separately. Due to the influence of noise, such as cam shocks, piston up-and-down motion, crank rotation and so on, the vibration signal should be processed to extract knock feature. Firstly, FFT, a frequency analysis approach, is used to determine the characteristic frequency range of knock. Then, combining the sampling frequency, the vibration signal is divided into different frequency sub-bands, and the characteristic sub-band of DWT, a time-frequency analysis method, is determined. After that, DWT is applied to extract knock feature from the vibration signal. At last, the knock energy evaluation index is used to judge knock intensity. The reference knock energy is chosen by the researchers, and it is not absolutely suitable for the engine operating condition, so intuitive cylinder pressure signal is applied to supplement for knock judgment. © (2014) Trans Tech Publications, Switzerland.

Yoshimitsu S.,Hayatocho Shinkou | Satonaka S.,Kurokami | Kawano Y.,Hayatocho Shinkou | Iwamoto C.,Kurokami | And 2 more authors.
Key Engineering Materials | Year: 2012

This report describes a two-dimensional monitoring system for milling machines using small-diameter tools. Small-diameter tools are used for high-speed milling, and they are indispensable for high-quality and high-productivity manufacturing. However, tool breakage occasionally occurs, and this becomes a serious problem in automated production. This study aims to develop a system for monitoring the cutting state that can prevent tool breakage. The proposed system consists of two charge-coupled device (CCD) cameras, an image processing device, a man-machine controller (MMC), and a machining center with an open computer numeric (CNC). This monitoring system is connected to the machining center by Ethernet. It enables the precise measurement of tool deflection during high-speed milling. In an experiment, we applied this system to the end milling of a steel plate under different cutting conditions, and we examined the relationship between tool deflection and the cutting conditions. In addition, we applied this monitoring system to measure tool wear, and we examined the relationship between tool deflection and tool wear. It was found that the proposed system enabled in-process monitoring of the cutting state and tool wear. © (2012) Trans Tech Publications, Switzerland.

Wang Y.,29 Yudao St | Yu K.,29 Yudao St | Tan J.,29 Yudao St
Key Engineering Materials | Year: 2014

A hydrodynamic experiment apparatus is constructed to accomplish the measurement of hydrodynamic force on three-dimensional. This paper firstly introduces the mechanical structure of the novel hydrodynamic experiment apparatus. Then, it introduces the mathematical modeling of the hydrodynamic experiment apparatus which is based on the relationship between measurement data and the force on experiment subject. Finally, the error source of the mechanical structure and load cells were analyzed and the error compensation model is established to improve the measurement accuracy. © (2014) Trans Tech Publications, Switzerland.

Wang Y.W.,29 Yudao St. | Tan J.B.,29 Yudao St. | Gu B.T.,29 Yudao St. | Sang P.F.,29 Yudao St. | Zhao D.B.,29 Yudao St.
Advanced Materials Research | Year: 2014

Freshwater stingrays employ enlarged undulating pectoral fins as their routine propulsion means. Their remarkable flexibility and maneuverability have provided many new inspirations for engineers. In this paper, a biomimetic stingray-like underwater robot was introduced. In order to investigate the mechanism of the undulatory propulsion, kinematic analysis and hydromechanics analysis were conducted. Lastly, underwater experiments were carried out to study the swimming performance of the robotic fish. © (2014) Trans Tech Publications, Switzerland.

Wang Y.,29 Yudao st. | Tan J.,29 Yudao st. | Gu B.,29 Yudao st. | Zhao D.,29 Yudao st.
Key Engineering Materials | Year: 2014

Fishes have evolved remarkable swimming abilities after years of evolution which inspire scientists and engineers to develop new underwater robots that mimic different kinds of fishes. Stingray is a unique species among median and/or paired fin (MPF) mode fishes which undulates the enlarged pectoral fins while swimming. In this paper, a biomimetic prototype design and a developed undulating fin propulsor that mimics stingrays are presented. Kinematic model of the undulating fin is built. The flexibility of the curved surface is checked by the fitting results. Detailed mechanism structure and control system design of the bionic prototype are illustrated. The simulation experiments of the propulsor were conducted on the ground and the results show that an approximated harmonic wave can be generated on each side fin. The feasibility of the motion control method is verified.

Wang Y.,29 Yudao St. | Gu B.,29 Yudao St. | Tan J.,29 Yudao St. | Sang P.,29 Yudao St.
Key Engineering Materials | Year: 2014

Stingrays have expanded and highly flexible pectoral fins that extend over the entire length of their body. Locomotion is controlled by modulations of the undulating fin surface which produce steady swimming, acceleration, or complex maneuvers. In this paper, a robotic fish inspired by stingray was presented. Structure of the biomimetic prototype and layout of the control system were illustrated. In order to mimic the undulations, parameters of the biomimetic pectoral fin need to be accurately controlled including frequency, amplitude, wavelength, and undulatory mode. Several control strategies were proposed to realize different kinds of locomotion. Lastly, swimming experiments were carried out in the water tank according to the control methods. Experiment results demonstrate the viability of our methods. © (2014) Trans Tech Publications, Switzerland.

Huang Z.,29 Yudao St | Zhao W.,29 Yudao St | He N.,29 Yudao St | Li L.,29 Yudao St
Materials Science Forum | Year: 2014

A strain based dynamometer used for the prediction and measurement of three-component cutting forces for milling operations has been designed on the basis of the principle of additional elastic element theory. Meanwhile, four Wheatstone bridges, considerable amplifier and data acquisition software based on LabVIEW are also used to compose a whole system acquiring the cutting force signals. In order to obtain higher natural frequency and magnification, this paper focuses on the calculation and optimization of the dimensions of the special structure, and finally its first natural frequency can be stabilized at more than 14kHz, which are high enough to precisely measure the cutting forces, and the magnification can also achieve up to 15. The dynamic characteristics of the dynamometer are studied theoretically and experimentally, the results show that the developed dynamometer is able to measure the dynamic force component in high-speed cutting. © (2014) Trans Tech Publications, Switzerland.

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