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Simulation of Turbulent combustion Flame Feature Based on Fractal Theory for SI engines

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Transactions of Tianjin University 2010年第4期16卷 256-261页

作者：张军杜青宋东先杨延相 internal combustion Engine Research Institute Tianjin University State Key Laboratory of engines Tianjin University

The flame structure of gasoline engine is complicated and has the characteristic of fractal geometry. A fractal combustion model was used to simulate the engine working cycle. Based on this model, the fractal dimension and laminar flame surface area of turbulent premixed flames were studied under different working conditions. The experimental system mainly includes an optical engine and a set of photography equipment used to shoot the images of turbulent flame of spark-ignition engine. The difference box-counting method was used to process 2D combustion images. In contrast to the experimental results, the computational results show that the fractal combustion model is an effective method of simulating the engine combustion process. The study provides a better understanding for flame structure and its propagation.

关键词： turbulent combustiom fractal simulation optical engine

Influence of Diesel Nozzle Geometry on Cavitation Using Eulerian Multi-Fluid Method

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Transactions of Tianjin University 2010年第1期16卷 33-39页

作者：张军杜青杨延相 internal combustion Engine Research Institute Tianjin University State Key Laboratory of engines Tianjin University

Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics(CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characteristics of a multi-hole diesel injector with the multi-phase flow model based on Eulerian multi-fluid *** diesel components in nozzle are considered as two continuous phases, diesel liquid and diesel vapor *** that both of them are fully coupled and interpenetrated, sepa...

关键词： diesel injection cavitation nozzle geometry multi-phase flow numerical simulation

DESIGN AND ANALYSIS OF NOVEL ACTIVE ACTUATOR TO CONTROL LOW FREQUENCY VIBRATIONS OF SHAFT SYSTEM

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 41-47页

作者： YU Yilong LIU Changwen YANG Yanxiang WANG Shuang ZHANG Junhong State Key Laboratory of engines School of Mechanical Engineering Tianjin University Tianjin 300072 China Tianjin internal combustion Engine Research Institute Tianjin University Tianjin 300072 China

Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrations is designed. The actuator employs electro-hydraulic system and can provide a high and circumferential load. To initialize new research, the characteristics of various kinds of active actuators to control rotor shaft vibration are briefly introduced. The purpose of this paper is to introduce the preliminary results via presenting the structure, functions and operating principles, in particular, the working process of the electro-hydraulic system of the new actuator which includes a set of high speed electromagnetic valves and a series of sloping cone-shaped openings, and presenting the transmission relationships among the control parameters from control signals into the valves to active load onto shaft. The course of the work is dynamic, and a series of spatial forces and moments are put on the shaft to get an external resultant force to reduce excitations that induce vibration of shafts. By checking states of vibration, the actuator can control the impulse width and the interval of injection time for applying different control force to a vibration shaft in two circumference directions through the regulating action of a set of combination directional control valves. The results from simulating analysis and experiment show evidence of that this design can satisfy the case of active process of decreasing of flexural and torsional vibrations.

关键词： Actuators Low frequency vibration Active control Large-scale rotation shafts System development

Small molecule inhibitor DDQ-treated hippocampal neuronal cells show improved neurite outgrowth and synaptic branching

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Neural Regeneration Research 2025年第9期20卷 2624-2632页

作者： Jangampalli Adi Pradeepkiran Priyanka Rawat Arubala P.Reddy Erika Orlov PHemachandra Reddy department of internal Medicine Texas Tech University Health Sciences CenterLubbockTXUSA department of Nutritional Sciences College of Human SciencesTexas Tech UniversityLubbockTXUSA department of Pharmacology&Neuroscience Texas Tech University Health Sciences CenterLubbockTXUSA department of Neurology Texas Tech University Health Sciences CenterLubbockTXUSA department of Speech Language and Hearing SciencesTexas Tech University Health Sciences CenterLubbockTXUSA department of Public Health Texas Tech University Health Sciences CenterLubbockTXUSA

The process of neurite outgrowth and branching is a crucial aspect of neuronal development and *** and dendrites,sometimes referred to as neurites,are extensions of a neuron's cellular body that are used to start *** we explored the effects of diethyl(3,4-dihydroxyphenethylamino)(quinolin-4-yl)methylphosphonate(DDQ)on neurite developmental features in HT22 neuronal *** this work,we examined the protective effects of DDQ on neuronal processes and synaptic outgrowth in differentiated HT22cells expressing mutant Tau(mTau)*** investigate DDQ chara cteristics,cell viability,biochemical,molecular,western blotting,and immunocytochemistry were *** outgrowth is evaluated through the segmentation and measurement of neural *** neural processes can be seen and measured with a fluorescence microscope by manually tracing and measuring the length of the neurite *** neuronal processes can be observed and quantified with a fluorescent microscope by manually tracing and measuring the length of the neuronal ***-treated mTau-HT22 cells(HT22 cells transfected with cDNA mutant Tau)were seen to display increased levels of synaptophysin,MAP-2,andβ-***,we confirmed and noted reduced levels of both total and p-Tau,as well as elevated levels of microtubule-associated protein 2,β-tubulin,synaptophysin,vesicular acetylcholine transporter,and the mitochondrial biogenesis protein-pe roxisome prolife rator-activated receptor-gamma coactivator-1α.In mTa u-expressed HT22 neurons,we observed DDQ enhanced the neurite characteristics and improved neurite development through increased synaptic *** findings conclude that mTa u-HT22(Alzheimer's disease)cells treated with DDQ have functional neurite developmental chara *** key finding is that,in mTa u-HT22 cells,DDQ preserves neuronal structure and may even enhance nerve development function with mTa u inhibition.

关键词： diethyl(3 4-dihydroxyphenethylamino)(quinolin-4-yl)methylphosphonate(DDQ) hippocampal neuronal cells HT22 neurite outgrowth neuronal development small molecule

The study on the relationship between breakup modes and gas-liquid interfaces

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Chinese Science Bulletin 2008年第18期53卷 2898-2906页

作者： DU Qing LIU Ning YIN Jun internal combustion Engine Research Institute Tianjin University Tianjin 300072 China Slate Key Laboratory of engines Tianjin University Tianjin 300072 China

Based on the linear instability analysis, the study on the relationship between breakup modes and gas-liquid interfaces of a viscous annular liquid jet moving in two swirling gas streams has been car- ried out. From the numerical results of the dispersion equation, the relevancy of the breakup mode between an annular liquid jet and two liquid jets of limiting cases, namely the cylindrical liquid jet and hollow gas jet, as well as the effects of injecting factors on the instability of an annular liquid jet, is studied in detail. Considering the effects of inner and outer interface radii on the instability of the jet, it is proved that the para-sinuous mode mainly relates to the inner interface, whereas the para-varicose mode mainly relates to the outer interface. The results also indicate that all the forces produced by liquid jet have similar impacts on either the instability of para-sinuous mode or para-varicose mode due to the fact that they can affect both inner and outer gas-liquid interfaces. On the other hand, all the forces exerting only on the inner interface have more powerful effects on the instability of para-sinuous mode, and all the forces exerting only on the outer interface have more powerful effects on the insta- bility of para-varicose mode. That is to say, the effects of forces are weakened greatly when penetrating the liquid jet.

关键词：气液反应液体喷射不稳定性衰弱模式

Application of virtual reality technology improves the functionality of brain networks in individuals experiencing pain

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World Journal of Clinical Cases 2025年第3期13卷 66-68页

作者： Takahiko Nagamine department of Psychiatric internal Medicine Sunlight Brain Research CenterHofu 7470066YamaguchiJapan

Medical procedures are inherently invasive and carry the risk of inducing pain to the mind and ***,efforts have been made to alleviate the discomfort associated with invasive medical procedures through the use of virtual reality(VR)*** has been demonstrated to be an effective treatment for pain associated with medical procedures,as well as for chronic pain conditions for which no effective treatment has been *** precise mechanism by which the diversion from reality facilitated by VR contributes to the diminution of pain and anxiety has yet to be ***,the provision of positive images through VR-based visual stimulation may enhance the functionality of brain *** salience network is diminished,while the default mode network is ***,the medial prefrontal cortex may establish a stronger connection with the default mode network,which could result in a reduction of pain and *** research into the potential of VR technology to alleviate pain could lead to a reduction in the number of individuals who overdose on painkillers and contribute to positive change in the medical field.

关键词： Virtual reality Pain Anxiety Salience network Default mode network

Experimental Study on Dimethyl Ether combustion Process in Homogeneous Charge Compression Ignition Mode

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Transactions of Tianjin University 2004年第4期10卷 241-246页

作者：郑尊清史春涛尧命发 State Key Laboratory of engines Tianjin UniversityTianjin 300072 China Tianjin internal combustion Engine Research Institute Tianjin University Tianjin 300072 China

Experimental study on homogeneous charge compression ignition （HCCI） combustion process was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether（DME）. The influence of inert gas CO2 on the ignition and combustion process was investigated. The research results indicate that because of the high cetane number of DME, the stable HCCI operating range is quite narrow while the engine has a high compression ratio. The HCCI operating range can be largely extended when the inert gas is inducted into the charging air. HCCI combustion of DME presents remarkable characteristic of two-stage combustion process. As the concentration of inert gas increases, the ignition timing of the first combustion stage delays, the peak heat release rate decreases, and the combustion duration extends. Inducting inert gas into charging air cannot make the combustion and heat release of DME occur at a perfect crank angle position. Therefore,to obtain HCCI operation for the fuel with high cetane number,other methods such as reducing engine compression ratio should be adopted. Emission results show that under HCCI operation, a nearly zero NOx emission can be obtained with no smoke emissions. But the HC and CO emissions are high, and both rise with the increase of the concentration of inert gases.

关键词： homogeneous charge compression ignition (HCCI) dimethyl ether(DME) combustion emission

Mixture Preparation and combustion of CNG Low-Pressure Compound Direct Injection Spark-Ignited engines

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Transactions of Tianjin University 2011年第6期17卷 411-417页

作者：胡春明侯圣智詹樟松刘斌刘娜于勇宋玺娟 internal combustion Engine Research Institute Tianjin University State Key Laboratory of engines Tianjin University Chongqing Chang' an Automobile Ltd. Co.

A set of compressed natural gas (CNG) multi-point direct injection system of spark-ignited engines and the corresponding measurement and data acquisition systems were developed in this paper. Based on different injection modes, the mixture formation and combustion of CNG low-pressure direct injection (LPDI) engines were studied under varying factors such as air/ fuel ratio, injection timing. Meanwhile, three-dimensional simulations were adopted to explain the mixture formation mechanisms of CNG low-pressure compound direct injection (LPCDI) mode. On the basis of test results and simulation of the mixture homogeneous degree, the conception of injection window was proposed, and the LPCDI mode was proved to be more beneficial to the mixture concentration stratification formation in cylinder under lean-burning conditions, which resulted in effective combustion and stability.

关键词： compressed natural gas (CNG) engine mixture homogeneous degree injection timing low pressure compound direct injection (LPCDI)

Diesel Engine Valve Clearance Fault Diagnosis Based on Features Extraction Techniques and FastICA-SVM

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Chinese Journal of Mechanical Engineering 2017年第4期30卷 991-1007页

作者： Ya-Bing Jing Chang-Wen Liu Feng-Rong Bi Xiao-Yang Bi Xia Wang Kang Shao State Key Laboratory of engines Tianjin UniversityTianjin 300072 China School of Mechanical Engineering Tianjin UniversityTianjin 300072 China internal combustion Engine Research Institute Tianjin University Tianjin 300072 China

Numerous vibration-based techniques are rarely used in diesel engines fault diagnosis in a direct way, due to the surface vibration signals of diesel engines with the complex non-stationary and nonlinear time-varying fea- tures. To investigate the fault diagnosis of diesel engines, fractal correlation dimension, wavelet energy and entropy as features reflecting the diesel engine fault fractal and energy characteristics are extracted from the decomposed signals through analyzing vibration acceleration signals derived from the cylinder head in seven different states of valve train. An intelligent fault detector FastICA-SVM is applied for diesel engine fault diagnosis and classification. The results demonstrate that FastlCA-SVM achieves higher classification accuracy and makes better general- ization performance in small samples recognition. Besides, the fractal correlation dimension and wavelet energy and entropy as the special features of diesel engine vibration signal are considered as input vectors of classifier FastlCA- SVM and could produce the excellent classification results. The proposed methodology improves the accuracy of fea- ture extraction and the fault diagnosis of diesel engines.

关键词： Feature extraction Diesel engine valve train FastlCA PCA Support vector machine