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Emergency diesel engine is the last safety barrier for nuclear power plants. Nuclear safety criteria require that it can start up to rated speed（ such as 1 500 r/min） within 10 seconds in an emergency and have loading conditions,so its startup performance is particularly important. During the start-up process,the power of high-pressure air is a key factor for success.In this paper,a vibration-based method by analyzing high-pressure air（ domestic units are generally 40 bar·g） power to evaluate starting performance is presented. The large amount of monitoring data obtained indicates that high-pressure air is rapidly charged into the cylinder to generate high-frequency（ approximately 11 kHz） gas exciting impact,and the impact phase will continue to shift backward with increasing speed. Firstly,the Teager energy operator and an adaptive threshold impact location method were used to automatically capture the high pressure gas impact area of each cylinder in each cycle of the start-up phase. Secondly,the energy of the local impact envelope was extracted to characterize the function of the high-pressure air. Finally,the gray evaluation method carried out a comprehensive assessment. The actual test result verifies the effectiveness of this method and has the value of popularization and application.

Reciprocating compressor stepless capacity control system in the petrochemical industry are widely used, unloading device as a key component of the system actuator, the action characteristics of the relationship between the quality of the system directly related to the efficiency of the air intake system and compressor valve life. In this paper, ANSYS/Ls-dyna explicit dynamics software is used to simulate the automatic opening process of the intake valve at the rated speed of the compressor. The displacement of the valve is measured by the eddy current displacement sensor. On the basis of this, the operation of the unloader under different oil supply pressure and different ejection time is simulated, the ideal hydraulic ejection force and the ejection phase are determined. It is concluded that the reasonable action of the unloader can effectively relieve the vibration of the valve plate and improve the force of the valve.

After the gear fault occurs， the vibration signal collected includes fault impact， deterministic meshing signal and noise signal， and these signals are also affected by the transmission path， which makes the gear fault feature extraction difficult. Cepstrum analysis is a common method for gear fault diagnosis. It can display the periodic components in the sideband as a single line， which is helpful for fault diagnosis. However， when the fault characteristic signal is weak， the fault characteristics in the cepstrum are not obvious. For this， feature-enhanced cepstrum analysis method is proposed. Three feature enhancement methods minimum entropy deconvolution， autoregressive linear prediction and wavelet de-noising are used to enhance the fault impact characteristics of gear vibration signals， and then the cepstrum is used to extract the fault features. The effectiveness of the proposed method is verified by experiment.

In this paper,simulation and experimental studies of typical wear fault of the reciprocating machinery connecting rod big end bearing,explore the influence of the wear and tear on the lubrication parameters of the connecting rod big end bearing. Based on the Reynolds equation,by simulating different bearing wear situations: different widths,different depths and different positions, a comprehensive analysis of the associations between the degrees of wear of bearing and lubrication parameters,in particular the bearing temperatures. By installing the temperature sensor in the test unit connecting rod bearings,connecting rod temperature is on-line monitored,and the variation rules of temperature of the bearing under the state of wear are experimental confirmed.

The model of diesel gear transmission system（ crank,crank gear,the intermediate gear,camshaft gear and camshaft） in an inline six-cylinder diesel engine is established to study. The multi-body dynamics simulation software ADAMS is used to simulate the frequency change of camshaft gear in normal and the fault of broken teeth,camshaft axial moving and intermediate gear radial vibration. Then the results are compared with the experimental data of gear broken tooth of diesel engine and comparison result shows that,when camshaft gear break tooth,each order frequency will increase,especially the fundamental frequency,three frequency multiplication,and four frequency multiplication. The phenomenon is identical with the actual failure case. When camshaft axial moving and intermediate gear radial vibration,each order frequency will increase significantly,especially the fundamental frequency,three frequency multiplication,and four frequency multiplication. Therefore,both cases may have resulted gear does not run smoothly,resulting in broken teeth failure.

A finite element analysis of gear broken tooth fault of diesel engine based on the ANSYS Workbench is presented. The model of a pair of involute helical gear which is built by Pro / E parametric modeling is imported into ANSYS Workbench transient dynamics analysis module and the finite element analysis results under three conditions including normal gear,half- tooth broken gear and full- tooth broken gear are obtained.Then the results are compared with the experimental vibration data of gear broken tooth fault of diesel engine and comparison result shows that,during the operation of involute helical gear of diesel engine,the contact stress changes periodically and fluctuates obviously,clearly impact phenomenon exists and with the increasing of the degree of gear tooth damage,the impact force of the gear increase distinctly. The frequency of the maximum amplitude is the ignition frequency,the amplitude of rotating frequency corresponding to fault vibration is significantly greater than the normal rotating gear.

Reciprocating compressor has many moving and damageable parts in which valve is the most frequently damaged component. A mathematical model of the valve movement was established according to its structure and motion characteristics.MATLAB and ANSYS software were used to study the transient motion law and the dynamic stress distribution of mesh valve.Then the impact of spring stiffness and transition arc on valve’s stress distribution was discussed. The results show that the stress generated by deformation is much greater than the impact stress. Maximum elastic deformation occurs in two thin elastic arms in which maximum equivalent stress generated. Changing the spring stiffness and the curvature of the transition arc can effectively reduce the stress and extend the life of the mesh valve. The results of the analysis have important theoretical significance for valve design optimization and the improvement of valve life.

Objective: To compare the biological characteristics of colorectal cancer associated fibroblasts (CAFs) with normal fibroblasts (NFs)., Methods: CAFs and NFs were isolated from fresh specimens of colorectal cancer and their paired normal colon tissue and cultured by tissue explant method. Light microscopy, quantitative polymerase chain reaction (qPCR), Western blot, immunofluorescence microscopy, electron microscopy and flow cytometry were used to identify isolated fibroblasts and to explore their characteristics of activation and growth., Results: Primary colorectal CAFs and NFs were isolated and cultured successfully. NFs showed spindled morphology and were arranged in interlacing or spiral bundles. CAFs were polygonal or spindle, but were fatter than NFs. They were distributed randomly and arranged irregularly, and had obvious actin expression. CAFs and NFs both expressed fibronectin, but not E-cadherin, CD31 and caldesmon. qPCR showed that CAFs expressed more fibroblast activation protein (FAP) and less fibroblast specific protein 1 (FSP1) than that of NFs. There was no difference in the expression of α-SMA between NFs and CAFs by Western blot. α-SMA was bundled in parallel to the long axis of the cell by immunofluorescence. By electron microscopy, CAFs but not NFs showed dense myofilament that was arranged regularly. Flow cytometry showed that the percentage of S- and G2-phase in CAFs were significantly lower than that in NFs. mRNA expression of transforming growth factor β1, stromal derived factor 1 (SDF-1) and platelet derived growth factor (PDGF)-D in CAFs were lower while that for PDGFC was higher than that in NFs. That indicated the proliferation of CAFs was inhibited and the secretion of some cytokines was different when compared with NFs., Conclusions: CAFs show differences with NFs in morphology, characteristics of activation and secretion of some cytokines. The proliferation of CAFs is down regulated as compared with NFs.