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Sonic velocity in holographic fluids and its applications
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作者 胡亚鹏 田雨 +2 位作者 吴小宁 李怀繁 张宏升 《中国物理C:英文版》 SCIE CAS CSCD 2019年第1期65-74,共10页
Gravity/fluid correspondence acts as an important tool in investigating the strongly correlated fluids. We carefully investigate the holographic fluids at the finite cutoff surface by considering different boundary co... Gravity/fluid correspondence acts as an important tool in investigating the strongly correlated fluids. We carefully investigate the holographic fluids at the finite cutoff surface by considering different boundary conditions in the scenario of gravity/fluid correspondence. We find that the sonic velocity of the boundary fluids at the finite cutoff surface is critical in clarifying the superficial similarity between the bulk viscosity and perturbation of the pressure for the holographic fluid, where we set a special boundary condition at the finite cutoff surface to explicitly express this superficial similarity. Moreover, we further take the sonic velocity into account to investigate a case with a more general boundary condition. In this more genaral case, although two parameters in the first order stress tensor of holographic fluid cannot be fixed, one can still extract the information about the transport coefficients by considering the sonic velocity seriously. 展开更多
关键词 gravity/fluid CORRESPONDENCE boundary condition BULK VISCOSITY sonic velocity
Response of size-fractionated phytoplankton to environmental factors near the Changjiang Estuary 预览
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作者 Li Li Jingyi Cen +1 位作者 Lei Cui Songhui Lu 《海洋学报:英文版》 SCIE CAS CSCD 2019年第1期151-159,共9页
Size-based partitioning of phytoplankton is a useful tool for monitoring key phytoplankton traits, and it provides a better understanding of phytoplankton dynamics. Our aim is to determine the variation in the differe... Size-based partitioning of phytoplankton is a useful tool for monitoring key phytoplankton traits, and it provides a better understanding of phytoplankton dynamics. Our aim is to determine the variation in the different size classes of phytoplankton to the total phytoplankton biomass during the spring and autumn of 2010 and examine the relationship between phytoplankton size structure and environmental variables and zooplankton community structure near the Changjiang Estuary. In the spring, phytoplankton populations were predominantly consisted of nanophytoplankton throughout the study region. In the autumn, picophytoplankton and nanophytoplankton collectively dominated the phytoplankton community. A Pearson correlation analysis highlighted the role of temperature and trophic conditions on the contributions of nanophytoplankton and picophytoplankton. The grazing pressure exerted by mesozooplankton could have played an important role in determining the microphytoplankton community structure. 展开更多
关键词 PHYTOPLANKTON size structure temperature TROPHIC condition seasonal SUCCESSION CHANGJIANG Estuary
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To Look Life in the Face: Characterization of the Novel The Hours 预览
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作者 雷筱 《海外英语》 2019年第8期220-223,共4页
Michael Cunningham's The Hours involves one day of three women of different times in different places. Studying on the characterization in it, it concludes women's dreary living condition and their consciousne... Michael Cunningham's The Hours involves one day of three women of different times in different places. Studying on the characterization in it, it concludes women's dreary living condition and their consciousness is in a crisis. Along with their struggle against time-consuming life, they still are faced up with dilemma and troubles, they have to make choices and compromises in their life to a certain degree. Pressure and disillusion behind their comfortable and carefree life penetrate their life. 展开更多
关键词 MICHAEL Cunningham The Hours CHARACTERIZATION LIVING CONDITION
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Major breakthrough of Well Gaotan 1 and exploration prospects of lower assemblage in southern margin of Junggar Basin, NW China 预览
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作者 DU Jinhu ZHI Dongming +5 位作者 LI Jianzhong YANG Disheng TANG Yong QI Xuefeng XIAO Lixin WEI Lingyun 《石油勘探与开发:英文版》 2019年第2期216-227,共12页
Well Gaotan 1 was tested a high yield oil and gas flow of more than 1 000 m~3 a day in the Cretaceous Qingshuihe Formation,marking a major breakthrough in the lower assemblage of the southern margin of Junggar Basin. ... Well Gaotan 1 was tested a high yield oil and gas flow of more than 1 000 m~3 a day in the Cretaceous Qingshuihe Formation,marking a major breakthrough in the lower assemblage of the southern margin of Junggar Basin. The lower assemblage in the southern margin of the Junggar Basin has favorable geological conditions for forming large Petroleum fields, including:(1) Multiple sets of source rocks, of which the Jurassic and Permian are the main source rocks, with a large source kitchen.(2) Multiple sets of effective reservoirs,namely Cretaceous Qingshuihe Formation, Jurassic Toutunhe Formation and the Khalza Formation etc.(3) Regional thick mudstone caprock of Cretaceous Tugulu Group, generally with abnormally high pressure and good sealing ability.(4) Giant structural traps and litho-stratigraphic traps are developed. The northern slope also has the conditions for large-scale litho-stratigraphic traps.(5) Static elements such as source rocks, reservoirs and caprocks are well matched, and the dynamic evolution is suitable for large oil and gas accumulation. The lower assemblage of the southern margin of the Junggar Basin has three favorable exploration directions, the Sikeshu Sag in the west part, the large structures in the middle and eastern part, and the northern slope. 展开更多
关键词 southern MARGIN of JUNGGAR Basin WELL Gaotan 1 LOWER ASSEMBLAGE accumulation condition exploration direction
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Dynamic stiffness method for free vibration of an axially moving beam with generalized boundary conditions 预览
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作者 Hu DING Minhui ZHU Liqun CHEN 《应用数学和力学:英文版》 SCIE EI CSCD 2019年第7期911-924,共14页
Axially moving beams are often discussed with several classic boundary conditions, such as simply-supported ends, fixed ends, and free ends. Here, axially moving beams with generalized boundary conditions are discusse... Axially moving beams are often discussed with several classic boundary conditions, such as simply-supported ends, fixed ends, and free ends. Here, axially moving beams with generalized boundary conditions are discussed for the first time. The beam is supported by torsional springs and vertical springs at both ends. By modifying the stiffness of the springs, generalized boundaries can replace those classical boundaries. Dynamic stiffness matrices are, respectively, established for axially moving Timoshenko beams and Euler-Bernoulli (EB) beams with generalized boundaries. In order to verify the applicability of the EB model, the natural frequencies of the axially moving Timoshenko beam and EB beam are compared. Furthermore, the effects of constrained spring stiffness on the vibration frequencies of the axially moving beam are studied. Interestingly, it can be found that the critical speed of the axially moving beam does not change with the vertical spring stiffness. In addition, both the moving speed and elastic boundaries make the Timoshenko beam theory more needed. The validity of the dynamic stiffness method is demonstrated by using numerical simulation. 展开更多
关键词 AXIALLY moving BEAM natural frequency TIMOSHENKO BEAM model DYNAMIC stiffness matrix generalized boundary condition
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Analytical solutions for buckling of size-dependent Timoshenko beams 预览
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作者 Xiaojian XU Mulian ZHENG 《应用数学和力学:英文版》 SCIE EI CSCD 2019年第7期953-976,共24页
The inconsistences of the higher-order shear resultant expressed in terms of displacement(s) and the complete boundary value problems of structures modeled by the nonlocal strain gradient theory have not been well add... The inconsistences of the higher-order shear resultant expressed in terms of displacement(s) and the complete boundary value problems of structures modeled by the nonlocal strain gradient theory have not been well addressed. This paper develops a size-dependent Timoshenko beam model that considers both the nonlocal effect and strain gradient effect. The variationally consistent boundary conditions corresponding to the equations of motion of Timoshenko beams are reformulated with the aid of the weighted residual method. The complete boundary value problems of nonlocal strain gradient Timoshenko beams undergoing buckling are solved in closed forms. All the possible higher-order boundary conditions induced by the strain gradient are selectively suggested based on the fact that the buckling loads increase with the increasing aspect ratios of beams from the conventional mechanics point of view. Then, motivated by the expression for beams with simply-supported (SS) boundary conditions, some semiempirical formulae are obtained by curve fitting procedures. 展开更多
关键词 BUCKLING STRAIN GRADIENT theory BOUNDARY condition
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Wind-induced instabilities and monitoring of wind turbine 预览
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作者 Isaac Wait Zhaohui (Joey) Yang +1 位作者 Gang Chen Benjamin Still 《地震工程与工程振动:英文版》 SCIE EI CSCD 2019年第2期475-485,共11页
This paper presents real-time monitoring data and analysis results of the non-stationary vibrations of an operational wind turbine. The advanced time-frequency spectrum analysis reveals varied non-stationary vibration... This paper presents real-time monitoring data and analysis results of the non-stationary vibrations of an operational wind turbine. The advanced time-frequency spectrum analysis reveals varied non-stationary vibrations with timevarying frequencies, which are correlated with certain system natural modes characterized by finite element analysis. Under the effects of strong wind load, the wind turbine system exhibits certain resonances due to blade passing excitations. The system also exhibits certain instabilities due to the coupling of the tower bending modes and blade flapwise mode with blade passing excitations under the variation of wind speed. An analytical model is used to elaborate the non-stationary and instability phenomena observed in experimental results. The properties of the nonlinear instabilities are evaluated by using Lyapunov exponent estimation. 展开更多
关键词 wind turbine condition MONITORING NON-STATIONARY vibrations INSTABILITIES whirl MODES WARM PERMAFROST
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High-temperature investigation of mould slag crystallization by single and double hot thermocouple techniques
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作者 Nathalie Kolbl Irmtraud Marschall Harald Harmuth 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第4期345-354,共10页
Methods for the characterization of mould slag crystallization with special emphasis on the single/double hot thermocouple technique(SHTT/DHTT)are reviewed.In the continuous casting process of steels,horizontal heat t... Methods for the characterization of mould slag crystallization with special emphasis on the single/double hot thermocouple technique(SHTT/DHTT)are reviewed.In the continuous casting process of steels,horizontal heat transfer is mainly influenced by the crystallization behaviour of the mould flux film.Here,both precipitation of crystals out of a liquid phase and devitrification of the glassy film in contact with the mould are of main interest.Therefore,various investigation methods are implemented to characterize different slag properties related to crystallization:a viscometer for determining the break temperature,differential thermal analysis(DTA),confocal scanning laser microscopy,and the water-cooled copper finger test.For near-service conditions,DHTT reveals the most detailed information,including not only the crystallization or devitrification temperature but also the morphology as well as the crystallization velocity.Due to improvements in the device and the representation of the results,a comparison of different samples is possible.Nevertheless,the application field of SHTT/DHTT is restricted to slag systems with low contents of evaporating components.Furthermore,the time required for data analysis is significantly longer than that required for other methods,e.g.DTA.Therefore,the application of DHTT is mainly advisable for mould slag research and development,whereas DTA can also be used for incoming inspections. 展开更多
关键词 Single HOT THERMOCOUPLE TECHNIQUE DOUBLE HOT THERMOCOUPLE TECHNIQUE Mould slag Near-service condition In situ INVESTIGATION CRYSTALLIZATION
Multiphysics simulation method of Lamb wavepropagation with piezoelectric transducers under load condition
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作者 Lei QIU Xixi YAN +1 位作者 Xiaodong LIN Shenfang YUAN 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第5期1071-1086,共16页
Lamb Wave(LW) simulation under time-varying conditions is an effective and low cost way to study the problem of the low reliability of the structural health monitoring methods based on the LW and Piezoelectric Transdu... Lamb Wave(LW) simulation under time-varying conditions is an effective and low cost way to study the problem of the low reliability of the structural health monitoring methods based on the LW and Piezoelectric Transducer(PT). In this paper, a multiphysics simulation method of the LW propagation with the PTs under load condition is proposed. With this method, two key mechanisms of the load influence on the LW propagation are considered and coupled with each other. The first mechanism is the acoustoelastic effect which is the main reason of the LW velocity change. The second key mechanism is the load influence on piezoelectric materials, which results in a change of the amplitude. Based on the computational platform of the COMSOL Multiphysics, a multiphysics simulation model of the LW propagation with the PTs under load condition is established. The simulation model includes two physical phenomena. The first one is called solid mechanics, which is used to simulate the acoustoelastic effect being combined with the hyperelastic material properties of the structure in which the LW propagates. The second one is called electromechanical coupling, which considers the simulation of the piezoelectric effect of the PTs for the LW excitation and sensing. To simulate the load influence on piezoelectric materials, a non-linear numerical model of the relationship between the load and the piezoelectric coefficient d31 is established based on an experiment of the load influence on the LW. The simulation results under uniaxial tensile load condition are obtained and are compared with the data obtained from the experiment. It shows that the variations of the phase velocity and amplitude of the LW obtained from the simulation model match the experimental results well. 展开更多
关键词 Acoustoelastic effect LAMB wave MULTIPHYSICS simulation PIEZOELECTRIC COEFFICIENT Structural health monitoring TIME-VARYING condition
Online condition diagnosis for a two-stage gearbox machinery of an aerospace utilization system using an ensemble multi-fault features indexing approach
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作者 Min ZHOU Ke WANG +3 位作者 Yang WANG Kaiji LUO Hongyong FU Liang SI 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第5期1100-1110,共11页
China manned space station is designed to operate for over ten years. Long-term and sustainable research on space science and technology will be conducted during its operation. The application payloads must meet the &... China manned space station is designed to operate for over ten years. Long-term and sustainable research on space science and technology will be conducted during its operation. The application payloads must meet the "long life and high reliability" mission requirement. Gearbox machinery is one of the essential devices in an aerospace utilization system, failure of which may lead to downtime loss even during some disastrous catastrophes. A fault diagnosis of gearbox has attracted attentions for its significance in preventing catastrophic accidents and guaranteeing sufficient maintenance. A novel fault diagnosis method based on the Ensemble Multi-Fault Features Indexing(EMFFI) approach is proposed for the condition monitoring of gearboxes. Different from traditional methods of signal analysis in the one-dimensional space, this study employs a supervised learning method to determine the faults of a gearbox in a two-dimensional space using the classification model established by training the features extracted automatically from diagnostic vibration signals captured. The proposed method mainly includes the following steps. First, the vibration signals are transformed into a bi-spectrum contour map utilizing bi-spectrum technology,which provides a basis for the following image-based feature extraction. Then, Speeded-Up Robustness Feature(SURF) is applied to automatically extract the image feature points of the bi-spectrum contour map using a multi-fault features indexing theory, and the feature dimension is reduced by Linear Discriminant Analysis(LDA). Finally, Random Forest(RF) is introduced to identify the fault types of the gearbox. The test results verify that the proposed method based on the multi-fault features indexing approach achieves the target of high diagnostic accuracy and can serve as a highly effective technique to discover faults in a gearbox machinery such as a two-stage one. 展开更多
关键词 Aerospace utilization SYSTEM Condition diagnosis Fault feature index GEARBOX MACHINERY Health monitoring Vibration
Sex and season explain spleen weight variation in the Egyptian mongoose
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作者 Victor BANDEIRA Emilio Virgos +3 位作者 Alexandre AZEVEDO Joao Carvalho Monica V. CUNHA Carlos Fonseca 《动物学报:英文版》 SCIE CAS CSCD 2019年第1期11-20,共10页
The Egyptia n mon goose (Herpestes ichneumon Linn aeus, 1758) is a medium-sized car nivore that experienced remarkable geographic expansion over the last 3 decades in the Iberian Peninsula. In this study, we investiga... The Egyptia n mon goose (Herpestes ichneumon Linn aeus, 1758) is a medium-sized car nivore that experienced remarkable geographic expansion over the last 3 decades in the Iberian Peninsula. In this study, we investigated the association of species-related and abiotic factors with spleen weight (as a proxy for immunocompete nee) in the species. We assessed the relationship of body con dition, sex, age, seas on, and envir onmental conditi ons with splee n weight established for 508 hunted specimens. Our results indicate that the effects of sex and season outweigh those of all other variables, including body condition. Spleen weight is higher in males than in females, and heavier spleens are more likely to be found in spring, coinciding with the highest period of investment in reproduction due to mating, gestation, birth, and lactation. Coupled with the absence of an effect of body condition, our findi ngs suggest that splee n weight variation in this species is mostly influe need by lifehistory traits linked to reproduction, rather than overall energy availability, winter immunoenhancement, or energy partitioning effects, and prompt further research focusing on this topic. 展开更多
关键词 body condition CARNIVORE Herpestes ichneumon Iberian Peninsula MONGOOSE SPLEEN WEIGHT
A data-driven health indicator extraction method for aircraft air conditioning system health monitoring
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作者 Jianzhong SUN Chaoyi LI +2 位作者 Cui LIU Ziwei GONG Ronghui WANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第2期409-416,共8页
Prognostics and Health Management(PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model,one of the challenges for airborne syste... Prognostics and Health Management(PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model,one of the challenges for airborne system health monitoring is to find an appropriate health indicator that is highly related to the actual degradation state of the system. This paper proposed a novel health indicator extraction method based on the available sensor parameters for the health monitoring of Air Conditioning System(ACS) of a legacy commercial aircraft model. Firstly, a specific Airplane Condition Monitoring System(ACMS) report for ACS health monitoring is defined. Then a non-parametric modeling technique is adopted to calculate the health indicator based on the raw ACMS report data. The proposed method is validated on a single-aisle commercial aircraft widely used for short and medium-haul routes, using more than 6000 ACMS reports collected from a fleet of aircraft during one year. The case study result shows that the proposed health indicator can effectively characterize the degradation state of the ACS, which can provide valuable information for proactive maintenance plan in advance. 展开更多
关键词 Air conditioning SYSTEM Aircraft HEALTH MONITORING Airplane condition MONITORING SYSTEM HEALTH INDICATOR PROGNOSTICS and HEALTH management
Nutritional stress reduces flight performance and exploratory behavior in a butterfly
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作者 Elisabeth Reim Danny Eichhorn +2 位作者 Jan D.Roy Philip O.M.Steinhoff Klaus Fischer 《昆虫科学:英文版》 SCIE CAS CSCD 2019年第5期897-910,共14页
Anthropogenic global change, including agricultural intensification and climate change, poses a substantial challenge to many herbivores due to a reduced availability of feeding resources. The concomitant food stress ... Anthropogenic global change, including agricultural intensification and climate change, poses a substantial challenge to many herbivores due to a reduced availability of feeding resources. The concomitant food stress is expected to detrimentally affect performance, amongst others in dispersal-related traits. Thus, while dispersal is of utmost importance to escape from deteriorating habitat conditions, such conditions may negatively feedback on the ability to do so. Therefore, we here investigate the impact of larval and adult food stress on traits related to dispersal ability, including morphology, physiology, flight performance, and exploratory behavior, in a butterfly. We show that inadequate nutrition during development and in the adult stage dim inishes flight performance, despite som e reallocation of somatic resources. Detrimental effects of food stress on flight performance were mainly caused by reductions in body mass and storage reserves. Similar results were found for exploratory behavior. Furthermore, exploratory behavior was found to be (moderately) repeatable at the individual level, which might indicate the existence of a personality trait. This notion is further supported by the fact that flight performance and exploratory behavior were positively correlated, potentially suggesting the existence of a dispersal syndrome. In summary, our findings may have important implications for dispersal in natural environments, as the conditions requiring dispersal the m ost impair flight ability and thereby likely dispersal rates. 展开更多
关键词 condition dispersal syndrome FLIGHT ABILITY food stress HABITAT degradation RESOURCE ALLOCATION
Multiple Positive Solutions to Singular Fractional Differential System with Riemann-Stieltjes Integral Boundary Condition 预览
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作者 Zhang Hai-yan Li Yao-hong 《数学研究通讯:英文版》 CSCD 2019年第3期208-218,共11页
In this paper, we study a class of singular fractional differential system with Riemann-Stieltjes integral boundary condition by constructing a new cone and using Leggett-Williams fixed point theorem. The existence of... In this paper, we study a class of singular fractional differential system with Riemann-Stieltjes integral boundary condition by constructing a new cone and using Leggett-Williams fixed point theorem. The existence of multiple positive solutions is obtained. An example is presented to illustrate our main results. 展开更多
关键词 FRACTIONAL differential equation positive solution INTEGRAL boundary condition fixed point THEOREM
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Optimization of Candida tropicalis Fermentation Conditions to Produce Long-chain Dibasic Acids 预览
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作者 Xiang XIU Junqing WANG 《农业生物技术:英文版》 CAS 2019年第2期160-164,共5页
[Objectives] The fermentation conditions of Candida tropicalis 1798- pxa 1 were optimized to further improve its yield of long-chain dibasic acids.[Methods] The strains used in the study were C. tropicalis 1798, C. tr... [Objectives] The fermentation conditions of Candida tropicalis 1798- pxa 1 were optimized to further improve its yield of long-chain dibasic acids.[Methods] The strains used in the study were C. tropicalis 1798, C. tropicalis 1798- pxa 1 and C. tropicalis 1798- pxa1p2 . First, through single factor experiments, the activated three fungi were cultured in different carbon sources, and the absorbance was measured every 2h. The growth curve was drawn by software, and finally the most suitable substance for the substrate was selected, i.e., dodecane. Then, the composition of the fermentation medium and the fermentation process parameters were determined through the PB experiment of the single-deletion C. tropicalis 1798- pxa1 .[Results] The experiment determined the important components affecting the synthesis of long-chain dibasic acids, namely (NH4)2SO4, NaCl and dodecane. After optimization of the culture conditions, the yield of long-chain dibasic acids of C. tropicalis 1798- pxa1 increased from 5.6 to 10.1 g/L.[Conclusions] The scheme has been verified to be capable of greatly increasing the yield of the corresponding long-chain dibasic acids of the C. tropicalis engineering strain. 展开更多
关键词 Synthesis of LONG-CHAIN dibasic acid CANDIDA TROPICALIS engineering FUNGUS Single factor EXPERIMENT PB EXPERIMENT Condition OPTIMIZATION
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Fault diagnosis based on measurement reconstruction of HPT exit pressure for turbofan engine
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作者 Xin ZHOU Feng LU Jinquan HUANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第5期1156-1170,共15页
Aero-engine gas path health monitoring plays a critical role in Engine Health Management(EHM). To achieve unbiased estimation, traditional filtering methods have strict requirements on measurement parameters which som... Aero-engine gas path health monitoring plays a critical role in Engine Health Management(EHM). To achieve unbiased estimation, traditional filtering methods have strict requirements on measurement parameters which sometimes cannot be measured in engineering. The most typical one is the High-Pressure Turbine(HPT) exit pressure, which is vital to distinguishing failure modes between different turbines. For the case of an abrupt failure occurring in a single turbine component, a model-based sensor measurement reconstruction method is proposed in this paper. First,to estimate the missing measurements, the forward algorithm and the backward algorithm are developed based on corresponding component models according to the failure hypotheses. Then,a new fault diagnosis logic is designed and the traditional nonlinear filter is improved by adding the measurement estimation module and the health parameter correction module, which uses the reconstructed measurement to complete the health parameters estimation. Simulation results show that the proposed method can well restore the desired measurement and the estimated measurement can be used in the turbofan engine gas path diagnosis. Compared with the diagnosis under the condition of missing sensors, this method can distinguish between different failure modes, quantify the variations of health parameters, and achieve good performance at multiple operating points in the flight envelope. 展开更多
关键词 Component-level model Condition monitoring FAULT diagnosis MEASUREMENT RECONSTRUCTION TURBOFAN engines Unscented KALMAN filter
悬挂式单轨车特殊工况对运行性能的影响
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作者 胡静涛 李芾 +2 位作者 吴晓 王建 徐银光 《电力机车与城轨车辆》 2019年第3期9-14,共6页
悬挂式单轨车近年来在我国发展迅速,其造价低、空间利用率高、爬坡能力强、运量大等优点较传统城市交通优势明显。针对悬挂式单轨车在运营过程中可能遇上的侧风和空气弹簧失效等特殊工况,通过多体系统动力学软件SIMPACK进行建模和仿真... 悬挂式单轨车近年来在我国发展迅速,其造价低、空间利用率高、爬坡能力强、运量大等优点较传统城市交通优势明显。针对悬挂式单轨车在运营过程中可能遇上的侧风和空气弹簧失效等特殊工况,通过多体系统动力学软件SIMPACK进行建模和仿真分析。结果表明:特殊运营工况对车辆运行平稳性影响较大,但都满足要求;在侧风曲线通过工况下,车体偏转较大并长时间作用在偏转止挡位置,因此为安全考虑应当减速运行;空气弹簧失效和斜置减振器失效工况下,车辆曲线通过性能变化不大,可以以原运行速度安全运行到车站检修。 展开更多
关键词 悬挂式单轨车 动力学性能 工况 仿真
Soft-sensing modeling and intelligent optimal control strategy for distillation yield rate of atmospheric distillation oil refining process
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作者 Zheng Wang Cheng Shao Li Zhu 《中国化学工程学报:英文版》 SCIE EI CAS CSCD 2019年第5期1113-1124,共12页
It is a challenge to conserve energy for the large-scale petrochemical enterprises due to complex production process and energy diversification. As critical energy consumption equipment of atmospheric distillation oil... It is a challenge to conserve energy for the large-scale petrochemical enterprises due to complex production process and energy diversification. As critical energy consumption equipment of atmospheric distillation oil refining process, the atmospheric distillation column is paid more attention to save energy. In this paper, the optimal problem of energy utilization efficiency of the atmospheric distillation column is solved by defining a new energy efficiency indicator — the distillation yield rate of unit energy consumption from the perspective of material flow and energy flow, and a soft-serising model for this new energy efficiency indicator with respect to the multiple working conditions and intelligent optimizing control strategy are suggested for both in creasing distillation yield and decreasing energy consumption in oil refining process. It is found that the energy utilization efficiency level of the atmospheric distillation column depends closely on the typical working conditions of the oil refining process, which result by changing the outlet temperature, the overhead temperature, and the bottom liquid level of the atmospheric pressure tower. The fuzzy C-means algorithm is used to classify the typical operation condi? tions of atmospheric distillation in oil refining process. Furthermore, the LSSVM method optimized with the improved particle swarm optimization is used to model the distillation rate of unit energy consumption. Then on line optimization of oil refining process is realized by optimizing the outlet temperature, the overhead temperature with IPSO again. Simulation comparative analyses are made by empirical data to verify the effectiveness of the proposed solution. 展开更多
关键词 Energy efficiency OPTIMIZATION CRUDE oil DISTILLATION Particle WARM OPTIMIZATION Fuzzy C-MEANS algorithm Working condition
Theoretical and experimental research on influence of rotor taper on performance of cone-shape helical pumps 预览
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作者 赵建华 Gao Dianrong Liu Shichang 《高技术通讯:英文版》 CAS 2019年第2期174-181,共8页
The structure of a rotor has full impact on the performance of cone-shaped helical pumps. Numerical simulation and experimental tests are applied to get pressure, velocity and flow of a cone-shaped helical pump, and e... The structure of a rotor has full impact on the performance of cone-shaped helical pumps. Numerical simulation and experimental tests are applied to get pressure, velocity and flow of a cone-shaped helical pump, and explores flow condition of blood in artificial blood pump. Rotors with four different tapers of artificial pump are designed. The flow condition of blood at the entrance, near the front diffuser, near the rotor, near the rear diffuser and at the exit, the pressure difference between entrance and exit and flow of artificial blood pump with different taper rotors are simulated, and then the influence rules of rotor taper on the performance of cone-shaped helical pump are revealed. In order to verify the correctness of theoretical analysis, rotors with three different tapers are manufactured, physical model of artificial blood pump are built, and then the actual lift and flow of blood pump with different rotors are measured respectively. The results show that taper of rotor increases, the circumfluence of blood near the front and rear diffuser decreases, the blood flows more smoothly, the energy consumption is less, and then the guide role of blade is greater. The blood at the exit of blood pump flows along the axial direction steadily. As taper of rotor increases, the pressure difference between the entrance and exit and the flow of blood pump increase subsequently. The flow condition of blood and performance of blood pump with No.3 rotor are the best. The proposed research analyzes the influence of rotor taper on performance of blood pump quantitatively, and provides the theoretical reference for the design and improving of cone-shaped helical pump. 展开更多
关键词 cone-shaped HELICAL PUMP ROTOR TAPER circumfluence flow condition energy consumption
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The geometrical properties of parity and time reversal operators in two dimensional spaces 预览
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作者 HUANG Min-yi YANG Yu +1 位作者 WU Jun-de CHO Min-Hyung 《高校应用数学学报:英文版(B辑)》 SCIE CSCD 2019年第2期173-183,共11页
The parity operator P and time reversal operator T are two important operators in the quantum theory, in particular, in the PT -symmetric quantum theory. By using the concrete forms of P and T , we discuss their geome... The parity operator P and time reversal operator T are two important operators in the quantum theory, in particular, in the PT -symmetric quantum theory. By using the concrete forms of P and T , we discuss their geometrical properties in two dimensional spaces. It is showed that if T is given, then all P links with the quadric surfaces;if P is given, then all T links with the quadric curves. Moreover, we give out the generalized unbroken PT -symmetric condition of an operator. The unbroken PT -symmetry of a Hermitian operator is also showed in this way. 展开更多
关键词 PT -symmetry GEOMETRICAL property unbroken condition
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