WorldWideScience

Sample records for dynamic characteristic analysis

  1. Dynamic characteristics analysis of deployable space structures considering joint clearance

    Science.gov (United States)

    Li, Tuanjie; Guo, Jian; Cao, Yuyan

    2011-04-01

    The clearance in joints influences the dynamic stability and the performance of deployable space structures (DSS). A virtual experimental modal analysis (VEMA) method is proposed to deal with the effects of joint clearance and link flexibility on the dynamic characteristics of the DSS in this paper. The focus is on the finite element modeling of the clearance joint, VEMA and the modal parameters identification of the DSS. The finite element models (FEM) of the clearance joint and the deployable structure are established in ANSYS. The transient dynamic analysis is conducted to provide the time history data of excitation and response for the VEMA. The fast Fourier transform (FFT) technique is used to transform the data from time domain to frequency domain. The frequency response function is calculated to identify the modal parameters of the deployable structure. Experimental verification is provided to indicate the VEMA method is both a cost and time efficient approach to obtain the dynamic characteristics of the DSS. Finally, we analyze the effects of clearance size and gravity on the dynamic characteristics of the DSS. The analysis results indicate that the joint clearance and gravity strongly influence the dynamic characteristics of the DSS.

  2. The Dynamic Characteristic Analysis of Mini Gamma Calorimeter

    International Nuclear Information System (INIS)

    Setiyanto

    2004-01-01

    The gamma calorimeter is a facility to measure the gamma heating in the nuclear reactor. The dimensions of the conventional calorimeters are in general too large, that is an inconvenience if those calorimeters will be applied in the high temperature reactor as a nuclear power plant. To avoid that inconvenience, it is necessary to propose the innovation on the feature of the existing calorimeter. The basic idea of the innovation is to create the small type of calorimeter without the absorbed material. The last analysis was realized to determine of the static calorimeter characteristic or sensitivities as a function of the dimension and the material of gas isolations. Based on those results, the analyses is reasonably to be continued to determine the dynamic characteristic or period of calorimeter. The analysis was performed using the finite difference method, two dimension simplified. It can be concluded that the mini gamma calorimeter proposed is reasonable to be made. (author)

  3. Dynamic Characteristics Analysis of Power Shift Control Valve

    Directory of Open Access Journals (Sweden)

    Feng Ren

    2014-07-01

    Full Text Available In order to study the influence that dynamic performance of shift control valve has on shifting process of construction machinery, the paper introduces working principle of the shift control valve and sets up the dynamically mathematical model and corresponding simulation model with simulation software LMS Imagine. Lab AMESim. Based on simulation, the paper analyzes the influence of pressure variation characteristics and buffering characteristics acting on vehicle performance during the process of shifting, meanwhile conducting experiments to verify the simulation. The results indicate that the simulation model is accurate and credible; the performance of the valve is satisfactory, which indeed reduces impact during shifting. Furthermore, the valve can meet the demand of other construction machineries in better degree by suitable matching between control spring stiffness and damping holes diameter.

  4. Practical Analysis of the Dynamic Characteristics of JavaScript

    OpenAIRE

    Wei, Shiyi

    2015-01-01

    JavaScript is a dynamic object-oriented programming language, which is designed with flexible programming mechanisms. JavaScript is widely used in developing sophisticated software systems, especially web applications. Despite of its popularity, there is a lack of software tools that support JavaScript for software engineering clients. Dataflow analysis approximates software behavior by analyzing the program code; it is the foundation for many software tools. However, several unique features...

  5. Analysis of Dynamic Characteristics of Water Injection Pump

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Myeong; Lee, Jeong Hoon; Ha, Jeong Min; Ahn, Byung Hyun; Kim, Won Cheol; Choi, Byeong Keun [Gyeongsang Nat' l Univ., Jinju (Korea, Republic of)

    2013-12-15

    Water injection pump outputs oil with high pressure during this process, seawater is injected into the well to recover the well pressure and maintain high productivity. A water injection pump has high productivity, and herefore, it serves as a key piece of equipment in marine plants. In this light, water injection pumps are being studied widely in industry. In this study, the rotor dynamics is analyzed to determine the natural frequency according to the bearing stiffness and operation speed change. This study aims to establish the pump reliability through critical speed, stability, and unbalance response analysis.

  6. Analysis of dynamic characteristics of stochastic influences in cognitive systems

    Directory of Open Access Journals (Sweden)

    Alexander A. Solodov

    2017-01-01

    Full Text Available The aim of the study is to provide an analytical description of the dynamics of the processes to form images in the cognitive system and their subsequent processing by the consciousness, as well as the study of the simplest characteristics of the quality of the cognitive system functioning in the form of the signal/noise ratio.In accordance with the ideas of the cognitive theory, it is believed that images (schemes, categories, Gestalt, systems, archetypes, etc. are firstly generated in the human brain and then processed by the consciousness.These images are formed at random in time and are characterized by a random force of effects and subsequently processed by the consciousness.The images are characterized by random numbers, the common interpretation of which is the amount of information corresponding to the appearance of a certain image. The times of appearance are points on the time axis; their number and position are random as well.The work consists of a logically completed model including the following components:• Justification of a statistical model of the appearance of effects during the operation of the cognitive system in the form of the Poisson point process, characterized by the intensity of occurrence of effects and the random values of those effects.• Development of a mathematical model in the consciousness processing of the random effects in the form of reducing response function, which depends on the current time, the time of occurrence of effects and the magnitudes of these effects. To obtain applied results, exponential response function was applied and the analytical results for the mathematical expectations of the processed and not processed information by the consciousness were received.• Introduction for consideration of the signal/noise ratio, characterizing the performance of cognitive systems in the presence of interference and study of its behavior in the situations with the presence of random background noise

  7. Structural Modeling and Analysis on Dynamic Characteristics of Antenna Pedestal in Airborne SAR

    Directory of Open Access Journals (Sweden)

    He Li-ping

    2012-06-01

    Full Text Available Finite element modeling and structural dynamic characteristics of antenna pedestal in airborne SAR were studied in this paper. The Finite element model of antenna pedestal in airborne SAR was set up on the basis of structural dynamic theory, then, the key technologies of dynamic simulation were pointed out, and the modal analysis and transient analysis were carried out. Simulation results show that the dynamic characteristics of antenna pedestal in airborne SAR can meet the requirements of servo bandwidth and structural strength. The fast finite element modeling and simulation method proposed in this paper are of great significance to the weight reducing design of antenna pedestal in airborne SAR.

  8. Analysis of Dynamic Characteristics of Portal Frame with Variable Section

    Directory of Open Access Journals (Sweden)

    Hao Jianing

    2016-01-01

    Full Text Available Combined with a portal frame design, by the use of finite element software ANSYS, the finite element model of single specimens of portal rigid frame and the overall portal rigid frame building are established. portal rigid frame’s beam and column is variable cross section. Through the modal analysis, comparative analysis of the frequency and vibration type of the radiolabeling specimens and finite element model of the whole, for the further development of variable cross-section portal rigid frame of earthquake and wind vibration analysis lay the foundation.

  9. Analysis of Dynamic Characteristics of Portal Frame with Variable Section

    OpenAIRE

    Hao Jianing

    2016-01-01

    Combined with a portal frame design, by the use of finite element software ANSYS, the finite element model of single specimens of portal rigid frame and the overall portal rigid frame building are established. portal rigid frame’s beam and column is variable cross section. Through the modal analysis, comparative analysis of the frequency and vibration type of the radiolabeling specimens and finite element model of the whole, for the further development of variable cross-section portal rigid f...

  10. Analysis of vorticity dynamics for hump characteristics of a pump turbine model

    Energy Technology Data Exchange (ETDEWEB)

    Li, Deyou; Gong, Ruzhi; Wang, Hongjie; Han, Lei; Wei, Xianzhu; Qin, Daqing [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin (China)

    2016-08-15

    Conventional parameters based on CFD methodology for the investigation on hump characteristics of a pump turbine cannot reflect the dynamic interaction mechanism between the runner and the fluid. This research presents a dynamic interaction mechanism of a pump turbine operating in the hump region. First, vorticity dynamic parameters were obtained based on the theory of vorticity dynamics. Second, 3-D unsteady flow simulations were performed in a full pump turbine model using the SST k-ω turbulence model, and numerical results have a good agreement with the experiments. Then, analysis was carried out to determine the relation between the vorticity dynamic parameters and hump characteristics. The results indicate that the theory of vorticity dynamics has an advantage in evaluating the dynamic performance of a pump turbine. The energy transfer between the runner and the fluid is through vorticity dynamic parameters-pressure and friction terms, in which the pressure term accounts for the most. Furthermore, vortex generation mainly results from the skin friction. Combining vorticity dynamic analysis with the method of Q-criterion indicates that hump characteristics are related to the reduction of the surface normal pressure work and vortex motion on the suction surfaces close to the leading edges in the runner, and the increase of skin friction work in the stay-guide vanes.

  11. Floating clamping mechanism of PT fuel injector and its dynamic characteristics analysis

    Science.gov (United States)

    Wang, Xinqing; Liang, Sheng; Xia, Tian; Wang, Dong; Qian, Shuhua

    2012-05-01

    PT fuel injector is one of the most important parts of modern diesel engine. To satisfy the requirements of the rapid and accurate test of PT fuel injector, the self-adaptive floating clamping mechanism was developed and used in the relevant bench. Its dynamic characteristics directly influence the test efficiency and accuracy. However, due to its special structure and complex oil pressure signal, related documents for evaluating dynamic characteristics of this mechanism are lack and some dynamic characteristics of this mechanism can't be extracted and recognized effectively by traditional methods. Aiming at the problem above-mentioned, a new method based on Hilbert-Huang transform (HHT) is presented. Firstly, combining with the actual working process, the dynamic liquid pressure signal of the mechanism is acquired. By analyzing the pressure fluctuation during the whole working process in time domain, oil leakage and hydraulic shock in the clamping chamber are discovered. Secondly, owing to the nonlinearity and nonstationarity of pressure signal, empirical mode decomposition is used, and the signal is decomposed and reconstructed into forced vibration, free vibration and noise. By analyzing forced vibration in the time domain, machining error and installation error of cam are revealed. Finally, free vibration component is analyzed in time-frequency domain with HHT, the traits of free vibration in the time-frequency domain are revealed. Compared with traditional methods, Hilbert spectrum has higher time-frequency resolutions and higher credibility. The improved mechanism based on the above analyses can guarantee the test accuracy of injector injection. This new method based on the analyses of the pressure signal and combined with HHT can provide scientific basis for evaluation, design improvement of the mechanism, and give references for dynamic characteristics analysis of the hydraulic system in the interrelated fields.

  12. Modelling and Analysis on Biomechanical Dynamic Characteristics of Knee Flexion Movement under Squatting

    Directory of Open Access Journals (Sweden)

    Jianping Wang

    2014-01-01

    Full Text Available The model of three-dimensional (3D geometric knee was built, which included femoral-tibial, patellofemoral articulations and the bone and soft tissues. Dynamic finite element (FE model of knee was developed to simulate both the kinematics and the internal stresses during knee flexion. The biomechanical experimental system of knee was built to simulate knee squatting using cadaver knees. The flexion motion and dynamic contact characteristics of knee were analyzed, and verified by comparing with the data from in vitro experiment. The results showed that the established dynamic FE models of knee are capable of predicting kinematics and the contact stresses during flexion, and could be an efficient tool for the analysis of total knee replacement (TKR and knee prosthesis design.

  13. Dynamic load-sharing characteristic analysis of face gear power-split gear system based on tooth contact characteristics

    Science.gov (United States)

    Dong, Hao; Hu, Yahui

    2018-04-01

    The bend-torsion coupling dynamics load-sharing model of the helicopter face gear split torque transmission system is established by using concentrated quality standard, to analyzing the dynamic load-sharing characteristic. The mathematical models include nonlinear support stiffness, time-varying meshing stiffness, damping, gear backlash. The results showed that the errors collectively influenced the load sharing characteristics, only reduce a certain error, it is never fully reached the perfect loading sharing characteristics. The system load-sharing performance can be improved through floating shaft support. The above-method will provide a theoretical basis and data support for its dynamic performance optimization design.

  14. Analysis of dynamic meshing characteristic of planetary gear transmission in wind power increasing gearbox

    Directory of Open Access Journals (Sweden)

    Wang Jungang

    2017-01-01

    Full Text Available Dynamic behavior of planetary gear’s tooth contact surface in the different location can better conform operation condition comparing to the general gear pair. Nonlinear finite element algorithm was derived according to the basic control equation of contact dynamics. A finite element model of planetary gear transmission in wind power increasing gearbox was proposed considering different meshing locations based on nonlinear finite element solution. The characteristics of stress distribution at different meshing positions were analyzed. A simulation of the meshing process was conducted using finite element analysis. It was shown that node stresses of external meshing planetary gear varied significantly at different position. The analysis provides some useful insights into the performance of planetary gear’s tooth contact surface.

  15. Dynamic response characteristics analysis of the doubly-fed wind power system under grid voltage drop

    Science.gov (United States)

    Chen, Y.; Wang, J.; Wang, H. H.; Yang, L.; Chen, W.; Xu, Y. T.

    2016-08-01

    Double-fed induction generator (DFIG) is sensitive to the disturbances of grid, so the security and stability of the grid and the DFIG itself are under threat with the rapid increase of DFIG. Therefore, it is important to study dynamic response of the DFIG when voltage drop failure is happened in power system. In this paper, firstly, mathematical models and the control strategy about mechanical and electrical response processes is respectively introduced. Then through the analysis of response process, it is concluded that the dynamic response characteristics are related to voltage drop level, operating status of DFIG and control strategy adapted to rotor side. Last, the correctness of conclusion is validated by the simulation about mechanical and electrical response processes in different voltage levels drop and different DFIG output levels under DIgSILENT/PowerFactory software platform.

  16. The analysis of dynamic characteristics and wind-induced displacement response of space Beam String Structure

    Directory of Open Access Journals (Sweden)

    Chen Yong Jian

    2018-01-01

    Full Text Available The Beam String Structure structural system, also called BSS, has the advantages of lighter dead weight and greater flexibility. The wind load is the main design control factor. The dynamic characteristics and wind-induced displacement response of BSS are studied by the finite element method. The roof structure of the stadium roof of the Fuzhou Olympic Sports Center is the engineering background. 1The numerical model was built by ANSYS, by shape finding, determine the initial stress state of structural members such as external cables; 2From the analysis of dynamic characteristics, the main mode of vibration is the vibration of cables; 3The wind speed spectrum of MATLAB generation structure is obtained by AR method, the structural response of the structure under static wind load and fluctuating wind load is calculated. From the analysis result, considering the equivalent static wind load of BSS , the design of adverse wind is not safe, and the fluctuating wind load should be taken into account.

  17. CFD analysis on the dynamic flow characteristics of the pilot-control globe valve

    International Nuclear Information System (INIS)

    Qian, Jin-yuan; Wei, Lin; Jin, Zhi-jiang; Wang, Jian-kai; Zhang, Han; Lu, An-le

    2014-01-01

    Highlights: • PCGV utilizes pressure difference to control the action of the valve core. • Three different opening processes with the same spring stiffness are analyzed. • Valve core’s displacements with different spring stiffness are analyzed. • The best design point of spring stiffness and inlet pressure is obtained. • The selection formula for the design of PCGV is generalized. - Abstract: The pilot-control globe valve (PCGV) is a new kind valve with simple structures and low driving energy consumption. It can utilize the pressure difference before and after the valve to control the action of the valve core. However, systematic theoretical research and numerical analysis are deficient at present. In this paper, the mathematical model of PCGV is established and Computational Fluid Dynamics (CFD) method is employed to numerically simulate its dynamic characteristics. Through the analysis of the internal flow field distribution, its working principle is verified. Then three different opening processes with the same spring stiffness are analyzed under different static inlet pressures, and the best design point is obtained by studying the characteristic curves of the valve core’s displacement. The relationship of static inlet pressure and the valve core’s displacement is summarized and the selection formula for the valve design is generalized which can reduce the various design work for further optimization and engineering applications of PCGV

  18. Characteristic analysis of rotor dynamics and experiments of active magnetic bearing for HTR-10GT

    International Nuclear Information System (INIS)

    Yang Guojun; Xu Yang; Shi Zhengang; Gu Huidong

    2005-01-01

    A 10 MW high-temperature gas-cooled reactor (HTR-10) was constructed by the Institute of Nuclear and New Energy Technology (INET) at Tsinghua University of China. The helium turbine and generator system of 10 MW high temperature gas-cooled reactor (HTR-10GT) is the second phase for the HTR-10 project. It is to set up a direct helium cycle to replace the current steam cycle. The active magnetic bearing (AMB) instead of ordinary mechanical bearing was chosen to support the rotor in the HTR-10GT. This rotor is vertically mounted to hold the turbine machine, compressors and the power generator together. The rotor's length is 7 m, its weight is about 1500 kg and the rotating speed is 15000 r/min. The structure of the rotor is so complicated that dynamic analysis of the rotor becomes difficult. One of the challenging problems is to exceed natural frequencies with enough stability and safety during reactor start up, power change and shutdown. The dynamic analysis of the rotor is the base for the design of control system. It is important for the rotor to exceed critical speeds. Some kinds of software and methods, such as MSC.Marc, Ansys, and the Transfer Matrix Method, are compared to fully analyze rotor dynamics characteristic in this paper. The modal analysis has been done for the HTR-10GT rotor. MSC.Marc was finally selected to analyze the vibration mode and the natural frequency of the rotor. The effects of AMB stiffness on the critical speeds of the rotor were studied. The design characteristics of the AMB control system for the HTR-10GT were studied and the related experiment to exceed natural frequencies was introduced. The experimental results demonstrate the system functions and validate the control scheme, which will be used in the HTR-10GT project. (authors)

  19. Analysis of Dynamic Coupling Characteristics of the Slope Reinforced by Sheet Pile Wall

    Directory of Open Access Journals (Sweden)

    H. L. Qu

    2017-01-01

    Full Text Available Large deformation of slope caused by earthquake can lead to the loss of stability of slope and its retaining structures. At present, there have been some research achievements about the slope reinforcement of stabilizing piles. However, due to the complexity of the structural system, the coupling relationship between soil and pile is still not well understood. Hence it is of great necessity to study its dynamic characteristics further. In view of this, a numerical model was established by FLAC3D in this paper, and the deformation and stress nephogram of sheet pile wall in peak ground motion acceleration (PGA at 0.1 g, 0.2 g, and 0.4 g were obtained. Through the analysis, some conclusions were obtained. Firstly, based on the nephogram of motion characteristics and the positions of the slip surface and the retaining wall, the reinforced slope can be divided into 6 sections approximatively, namely, the sliding body parts of A, B, C, D, and E and the bedrock part F. Secondly, the deformation and stress distributions of slope reinforced by sheet pile wall were carefully studied. Based on the results of deformation calculation from time history analysis, the interaction force between structure and soil can be estimated by the difference of peak horizontal displacements, and the structure-soil coupling law under earthquake can be studied by this approach.

  20. Sensitivity analysis of dynamic characteristic of the fixture based on design variables

    International Nuclear Information System (INIS)

    Wang Dongsheng; Nong Shaoning; Zhang Sijian; Ren Wanfa

    2002-01-01

    The research on the sensitivity analysis is dealt with of structural natural frequencies to structural design parameters. A typical fixture for vibration test is designed. Using I-DEAS Finite Element programs, the sensitivity of its natural frequency to design parameters is analyzed by Matrix Perturbation Method. The research result shows that the sensitivity analysis is a fast and effective dynamic re-analysis method to dynamic design and parameters modification of complex structures such as fixtures

  1. Analysis of the dynamic behavior and lubrication characteristics of a small reciprocating compressor

    International Nuclear Information System (INIS)

    Kim, Tae Jong

    2003-01-01

    In this paper, a study on the dynamic behavior and lubrication characteristics of a reciprocating compression mechanism used in small refrigeration compressor is performed. In the problem formulation of the compressor dynamics, the viscous frictional force between piston and cylinder wall is considered in order to determine the coupled dynamic behaviors of piston and crankshaft. The solutions of the equations of motion of the reciprocating mechanism along with the time dependent Reynolds equations for the lubricating film between piston and cylinder wall and oil films of the journal bearings are obtained simultaneously. The hydrodynamic forces of journal bearings are calculated using finite bearing model and Gumbel boundary condition. And, a Newton-Raphson procedure was employed in solving the nonlinear equations of piston and crankshaft. The results explored the effects of design parameters on the stability and lubrication characteristics of the compression mechanism

  2. Dynamic characteristics and finite element analysis of a magnetic levitation system using a YBCO bulk superconductor

    International Nuclear Information System (INIS)

    Ueda, H; Ishiyama, A

    2004-01-01

    We have been developing a magnetic levitating device with two-dimensional movement, namely a 'levitating X-Y transporter'. For the real design of a levitating X-Y transporter, it is necessary to clarify the levitation characteristics, such as the lift, the levitation height and the stability against mechanical disturbances. Furthermore various kinds of force may be applied to the levitating part and cause mechanical oscillation. Therefore the characteristics of oscillation are also important factors in the dynamic stability of such a levitation system. In this paper, we examine experimentally the lift and the restoring force and develop a new simulation code based on the three-dimensional hybrid finite and boundary element method to analyse the dynamic electromagnetic behaviour of the HTS bulk. We have investigated a suitable permanent-magnet arrangement to enhance the levitation characteristics through experiment and numerical simulation. We can then determine the suitable conditions for stable levitation from those results

  3. Analysis of Dynamic Characteristics of the 21st Century Maritime Silk Road

    Science.gov (United States)

    Zhang, Xudong; Zhang, Jie; Fan, Chenqing; Meng, Junmin; Wang, Jing; Wan, Yong

    2018-06-01

    The 21st century Maritime Silk Road (MSR) proposed by China strongly promotes the maritime industry. In this paper, we use wind and ocean wave datasets from 1979 to 2014 to analyze the spatial and temporal distributions of the wind speed, significant wave height (SWH), mean wave direction (MWD), and mean wave period (MWP) in the MSR. The analysis results indicate that the Luzon Strait and Gulf of Aden have the most obvious seasonal variations and that the central Indian Ocean is relatively stable. We analyzed the distributions of the maximum wind speed and SWH in the MSR over this 36-year period. The results show that the distribution of the monthly average frequency for SWH exceeds 4 m (huge waves) and that of the corresponding wind speed exceeds 13.9 m s-1 (high wind speed). The occurrence frequencies of huge waves and high winds in regions east of the Gulf of Aden are as high as 56% and 80%, respectively. We also assessed the wave and wind energies in different seasons. Based on our analyses, we propose a risk factor (RF) for determining navigation safety levels, based on the wind speed and SWH. We determine the spatial and temporal RF distributions for different seasons and analyze the corresponding impact on four major sea routes. Finally, we determine the spatial distribution of tropical cyclones from 2000 to 2015 and analyze the corresponding impact on the four sea routes. The analysis of the dynamic characteristics of the MSR provides references for ship navigation as well as ocean engineering.

  4. Dynamic Characteristics Analysis and Stabilization of PV-Based Multiple Microgrid Clusters

    DEFF Research Database (Denmark)

    Zhao, Zhuoli; Yang, Ping; Wang, Yuewu

    2018-01-01

    -based multiple microgrid clusters. A detailed small-signal model for PV-based microgrid clusters considering local adaptive dynamic droop control mechanism of the voltage-source PV system is developed. The complete dynamic model is then used to access and compare the dynamic characteristics of the single...... microgrid and interconnected microgrids. In order to enhance system stability of the PV microgrid clusters, a tie-line flow and stabilization strategy is proposed to suppress the introduced interarea and local oscillations. Robustly selecting of the key control parameters is transformed to a multiobjective......As the penetration of PV generation increases, there is a growing operational demand on PV systems to participate in microgrid frequency regulation. It is expected that future distribution systems will consist of multiple microgrid clusters. However, interconnecting PV microgrids may lead to system...

  5. Patient Specific Characteristic of Brain Dynamic in Interpretation of Long Term EEG Analysis

    Czech Academy of Sciences Publication Activity Database

    Komárek, V.; Paluš, Milan; Hrnčíř, Z.

    2004-01-01

    Roč. 45, Suppl. 3 (2004), s. 51 ISSN 0013-9580. [European Congress on Epileptology /6./. 30.05.2004-03.06.2004, Vienna] R&D Projects: GA MŠk ME 701 Institutional research plan: CEZ:AV0Z1030915 Keywords : brain dynamic * long term EEG analysis Subject RIV: FH - Neurology

  6. Analysis of the flow dynamics characteristics of an axial piston pump based on the computational fluid dynamics method

    Directory of Open Access Journals (Sweden)

    Bin Zhang

    2017-01-01

    Full Text Available To improve its working performance, the flow ripple characteristics of an axial piston pump were investigated with software which uses computational fluid dynamics (CFD technology. The simulation accuracy was significantly optimized through the use of the improved compressible fluid model. Flow conditions of the pump were tested using a pump flow ripple test rig, and the simulation results of the CFD model showed good agreement with the experimental data. Additionally, the composition of the flow ripple was analyzed using the improved CFD model, and the results showed that the compression ripple makes up 88% of the flow ripple. The flow dynamics of the piston pump is mainly caused by the pressure difference between the intake and discharge ports of the valve plates and the fluid oil compressibility.

  7. The Finite Element Modelling and Dynamic Characteristics Analysis about One Kind of Armoured Vehicles’ Fuel Tanks

    Science.gov (United States)

    Gao, Yang; Ge, Zhishang; Zhai, Weihao; Tan, Shiwang; Zhang, Feng

    2018-01-01

    The static and dynamic characteristics of fuel tank are studied for the armoured vehicle in this paper. The CATIA software is applied to build the CAD model of the armoured vehicles’ fuel tank, and the finite element model is established in ANSYS Workbench. The finite element method is carried out to analyze the static and dynamic mechanical properties of the fuel tank, and the first six orders of mode shapes and their frequencies are also computed and given in the paper, then the stress distribution diagram and the high stress areas are obtained. The results of the research provide some references to the fuel tanks’ design improvement, and give some guidance for the installation of the fuel tanks on armoured vehicles, and help to improve the properties and the service life of this kind of armoured vehicles’ fuel tanks.

  8. Analysis of BF Hearth Reasonable Cooling System Based on the Water Dynamic Characteristics

    Science.gov (United States)

    Zuo, Haibin; Jiao, Kexin; Zhang, Jianliang; Li, Qian; Wang, Cui

    A rational cooling water system is the assurance for long campaign life of blast furnace. In the paper, the heat transfer of different furnace period and different furnace condition based on the water quality characteristics were analysed, and the reason of the heat flux over the normal from the hydrodynamics was analysed. The results showed that, the vapour-film and scale existence significantly influenced the hearth heat transfer, which accelerated the brick lining erosion. The water dynamic characteristics of the parallel inner pipe or among the pipes were the main reason for the abnormal heat flux and film boiling. As to the reasonable cooling water flow, the gas film and the scale should be controlled and the energy saving should be considered.

  9. An analysis of the synoptic and dynamical characteristics of hurricane Sandy (2012)

    Science.gov (United States)

    Varlas, George; Papadopoulos, Anastasios; Katsafados, Petros

    2018-01-01

    Hurricane Sandy affected the Caribbean Islands and the Northeastern United States in October 2012 and caused 233 fatalities, severe rainfalls, floods, electricity blackouts, and 75 billion U.S. dollars in damages. In this study, the synoptic and dynamical characteristics that led to the formation of the hurricane are investigated. The system was driven by the interaction between the polar jet displacement and the subtropical jet stream. In particular, Sandy was initially formed as a tropical depression system over the Caribbean Sea and the unusually warm sea drove its intensification. The interaction between a rapidly approaching trough from the northwest and the stagnant ridge over the Atlantic Ocean drove Sandy to the northeast coast of United States. To better understand the dynamical characteristics and the mechanisms that triggered Sandy, a non-hydrostatic mesoscale model has been used. Model results indicate that the surface heat fluxes and the moisture advection enhanced the convective available potential energy, increased the low-level convective instability, and finally deepened the hurricane. Moreover, the upper air conditions triggered the low-level frontogenesis and increased the asymmetry of the system which finally affected its trajectory.

  10. Dynamic modeling and characteristics analysis of a modal-independent linear ultrasonic motor.

    Science.gov (United States)

    Li, Xiang; Yao, Zhiyuan; Zhou, Shengli; Lv, Qibao; Liu, Zhen

    2016-12-01

    In this paper, an integrated model is developed to analyze the fundamental characteristics of a modal-independent linear ultrasonic motor with double piezoelectric vibrators. The energy method is used to model the dynamics of the two piezoelectric vibrators. The interface forces are coupled into the dynamic equations of the two vibrators and the moving platform, forming a whole machine model of the motor. The behavior of the force transmission of the motor is analyzed via the resulting model to understand the drive mechanism. In particular, the relative contact length is proposed to describe the intermittent contact characteristic between the stator and the mover, and its role in evaluating motor performance is discussed. The relations between the output speed and various inputs to the motor and the start-stop transients of the motor are analyzed by numerical simulations, which are validated by experiments. Furthermore, the dead-zone behavior is predicted and clarified analytically using the proposed model, which is also observed in experiments. These results are useful for designing servo control scheme for the motor. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Management of research reactor; dynamic characteristics analysis for reactor structures related with vibration of HANARO fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Chang Kee; Shim, Joo Sup [Shinwa Technology Information, Seoul (Korea)

    2001-04-01

    The objective of this study is to deduce the dynamic correlation between the fuel assembly and the reactor structure. Dynamic characteristics analyses for reactor structure related with vibration of HANARO fuel assembly have been performed For the dynamic characteristic analysis, the in-air models of the round and hexagonal flow tubes, 18-element and 36-element fuel assemblies, and reactor structure were developed. By calculating the hydrodynamic mass and distributing it on the in-air models, the in-water models of the flow tubes, the fuel assemblies, and the reactor structure were developed. Then, modal analyses for developed in-air and in-water models have been performed. Especially, two 18-element fuel assemblies and three 36-element fuel assemblies were included in the in-water reactor models. For the verification of the modal analysis results, the natural frequencies and the mode shapes of the fuel assembly were compared with those obtained from the experiment. Finally the analysis results of the reactor structure were compared with them performed by AECL Based on the reactor model without PCS piping, the in-water reactor model including the fuel assemblies was developed, and its modal analysis was performed. The analysis results demonstrate that there are no resonance between the fuel assembly and the reactor structures. 26 refs., 419 figs., 85 tabs. (Author)

  12. A modeling study of dynamic characteristic analysis of isolated structure for seismic exciting tests

    International Nuclear Information System (INIS)

    Lee, Jae Han; Koo, G. H.; Yoo, Bong

    1998-04-01

    The fundamental frequency of the isolated superstructure for seismic exciting tests was calculated by 16 Hz with a initial modal analysis model. but the actual modal test resulted in 5 Hz. This large difference was resulted from some uncertainties in analysis modeling of several connection parts between column and upper beam, cross bars of each face of the isolated superstructure. When the stiffness of cross-bars are larger than certain level in all the analyses, the joint stiffness between main slab and columns does not effect to the fundamental frequency. So the fundamental frequency of the isolated superstructure was governed by the cross-bar's stiffness. In actual tests the first and second frequencies show a little difference regardless of the cross section characteristics (inertia moments) of four columns because the joint stiffness between column and main slab is less than 10 8 1b f in/radian. The mounting device of each column to main slab, and the bolting device of each column to upper beam are fabricated with lower stiffness compared to design value. The bolting of cross-bars and the fitness of bolt-hole to bolt were loosed during the modal tests. In the future the tight connecting and the precise assembling of isolated superstructure are required to reduce the difference of the fundamental frequencies obtained from the modal analysis and actual test. (author). 4 refs

  13. Dynamic analysis of Lactobacillus delbrueckii subsp. bulgaricus CFL1 physiological characteristics during fermentation.

    Science.gov (United States)

    Rault, Aline; Bouix, Marielle; Béal, Catherine

    2008-12-01

    This study aimed at examining and comparing the relevance of various methods in order to discriminate different cellular states of Lactobacillus bulgaricus CFL1 and to improve knowledge on the dynamics of the cellular physiological state during growth and acidification. By using four fluorescent probes combined with multiparametric flow cytometry, membrane integrity, intracellular esterase activity, cellular vitality, membrane depolarization, and intracellular pH were quantified throughout fermentations. Results were compared and correlated with measurements of cultivability, acidification activity (Cinac system), and cellular ability to recover growth in fresh medium (Bioscreen system). The Cinac system and flow cytometry were relevant to distinguish different physiological states throughout growth. Lb. bulgaricus cells maintained their high viability, energetic state, membrane potential, and pH gradient in the late stationary phase, despite the gradual decrease of both cultivability and acidification activity. Viability and membrane integrity were maintained during acidification, at the expense of their cultivability and acidification activity. Finally, this study demonstrated that the physiological state during fermentation was strongly affected by intracellular pH and the pH gradient. The critical pHi of Lb. bulgaricus CFL1 was found to be equal to pH 5.8. Through linear relationships between dpH and cultivability and pHi and acidification activity, pHi and dpH well described the time course of metabolic activity, cultivability, and viability in a single analysis.

  14. Dynamic modeling and vibration characteristics analysis of the aero-engine dual-rotor system with Fan blade out

    Science.gov (United States)

    Yu, Pingchao; Zhang, Dayi; Ma, Yanhong; Hong, Jie

    2018-06-01

    Fan Blade Out (FBO) from a running rotor of the turbofan engine will not only introduce the sudden unbalance and inertia asymmetry into the rotor, but also apply large impact load and induce rotor-to-stator rubbing on the rotor, which makes the mass, gyroscopic and stiffness matrixes of the dynamic equation become time-varying and highly nonlinear, consequently leads to the system's complicated vibration. The dynamic analysis of the aero-engine rotor system is one essential requirement of the authorities and is vital to the aero-engine's safety. The paper aims at studying the dynamic responses of the complicated dual-rotor systems at instantaneous and windmilling statuses when FBO event occurs. The physical process and mechanical characteristics of the FBO event are described qualitatively, based on which the dynamic modeling for an aero-engine dual-rotor system is carried out considering several excitations caused by FBO. Meanwhile the transient response during the instantaneous status and steady-state response at the windmilling status are obtained. The results reveal that the sudden unbalance can induce impact load to the rotor, and lead to the sharp increase of the vibration amplitude and reaction force. The rub-impact will apply constraint effects on the rotor and restrict the transient vibration amplitude, while the inertia asymmetry has little influence on the transient response. When the rotor with huge unbalance operates at windmilling status, the rub-impact turns to be the main factor determining the rotor's dynamic behavior, and several potential motion states, such as instable dry whip, intermittent rubbing and synchronous full annular rubbing would happen on certain conditions.

  15. Dynamic modeling and analysis of load sharing characteristics of wind turbine gearbox

    Directory of Open Access Journals (Sweden)

    Pengxing Yi

    2015-03-01

    Full Text Available A coupled dynamic model, which contains helical gears-shafts-bearings for a wind turbine gearbox transmission system, was built considering nonlinear factors of the time-varying mesh stiffness, the external varying load, and the dynamic transmission error at first. The model is confirmed to be right after comparing the theoretical data with the experimental load sharing values, and also it is found that the static load sharing is conservative to evaluate the non-equilibrium effect of a planetary gear system. Besides, the analyzing results of the influence of average error and amplitude error on the load sharing show that the load sharing could be decreased if the error goes up a little. Then, by means of treating the static tracing point as the dynamic initial values, we analyzed the initial position’s influence on the load sharing of transmission system to provide a theoretical basis of load sharing control. Furthermore, we explored the influence of high-speed shaft position angle on the load sharing and the dynamic load factor of gears fixed on the parallel shafts. The results provide useful theoretical guidelines for the design of parallel shaft gear system in the wind turbines.

  16. Dynamic characteristic analysis of mother to child transmission of HIV in India

    Directory of Open Access Journals (Sweden)

    A. S. Kadi

    2014-01-01

    Full Text Available In this study, a mathematical model of HIV/AIDS mother to child transmission to analyze the effectiveness of prevention of HIV mother to child transmission programmes has been presented. The result reveals that prevention of HIV mother to child transmission programmes focusing only on biological transmission cannot control the increase of the HIV mother to child transmission in India. Hence, to control the HIV MTCT epidemic in India, in spite of strengthening the PMTCT programmes to reduce transmission rates, effective measures should be taken to prevent HIV infection in women of reproductive ages. Since the overall HIV MTCT epidemic is dependent on the HIV incidence in women of reproductive age group, the integration of pediatric HIV model with a detailed model of adult HIV would be investigated in future studies in order to model these dynamics more accurately.

  17. Analysis of neutronics and dynamic characteristics with reactivity injection in LBE cooled sub-critical reactor

    International Nuclear Information System (INIS)

    Chen Sen; Wu Yican; Jin Ming; Chen Zhibin; Bai Yunqing; Zhao Zhumin

    2014-01-01

    Accelerator Driven Sub-critical System (ADS) has particular neutronics behaviors compared with the critical system. Prompt jump approximation point reactor kinetics equations taken external source into account have been deduced using an approach of prompt jump approximation. And the relationship between injection reactivity and power ampliation has been achieved. In addition, based on the RELAP5 code the prolong development of point reactor kinetics code used into assessing sub-critical system have been promoted. Different sub-criticality (k eff = 0.90, 0.95, 0.97, 0.98 and 0.99) have been assessed in preliminary design of a type of natural circulation cooling sub-critical reactor under conditions of reactivity injection +1 β in one second. It shows that the external source prompt transient approximation method has an accurate solution after injecting reactivity around short time and has a capacity to solve the dynamic equation, and the sub-critical system has an inner stability while the deeper sub-criticality the less impact on the sub-critical system. (authors)

  18. The Dynamic Characteristic Analysis of the Water Lubricated Bearing-Rotor System in Seawater Desalination Pump

    Directory of Open Access Journals (Sweden)

    Xiaoyan Ye

    2014-05-01

    Full Text Available In order to study the water lubricated bearing-rotor system in seawater desalination pump, this paper is based on the coupling between the lubricating flow field and the rotor dynamics. The fluid-solid interaction (FSI method, Rigid Body, was adopted to study the journal orbit of the bearing-rotor system under the periodic unbalancing load. The influences of geometric and working parameter to the journal orbit were combined to analyze the stability and reliability of the bearing-rotor system. The result shows that increasing the rotating speed would increase the journal whirling amplitude and the system sensitivity to the external excitation and unbalancing load were promoted; increasing the aspect ratio would reduce the journal whirling amplitude and cause the system to be more unstable; increasing the inlet pressure would reduce the journal whirling amplitude and cause the system to be more unstable; increasing the unbalancing load would reduce the stability margin and the system is easy to be unstable if obstructed; increasing the radial clearance would reduce the journal whirling amplitude and cause the system to be more unstable. The attitude angle has no influence on the journal whirling amplitude but would influence the stability of system and the value of attitude angle should not be large.

  19. Dynamic characteristics of automotive steel sheets

    Directory of Open Access Journals (Sweden)

    M. Mihaliková

    2016-10-01

    Full Text Available The aim of this experimental research was to perform an analysis of deformation characteristics on two different types of steel: IF steel, and micro-alloyed steel were used automotive industry. For that purpose changes of properties of these materials were carried out by static 10-3 · s-1 and dynamic 103 · s-1 strain rate assess its plastic properties. Vickers micro hardness test was carried out by the static and dynamic loading condition and describes different hardness distribution. The higher strain hardening of materials was obtained too that was confirmed by distribution of dislocations.

  20. Modeling and Analysis of Static and Dynamic Characteristics of Nonlinear Seat Suspension for Off-Road Vehicles

    OpenAIRE

    Yan, Zhenhua; Zhu, Bing; Li, Xuefei; Wang, Guoqiang

    2015-01-01

    Low-frequency vibrations (0.5–5 Hz) that harm drivers occur in off-road vehicles. Thus, researchers have focused on finding methods to effectively isolate or control low-frequency vibrations. A novel nonlinear seat suspension structure for off-road vehicles is designed, whose static characteristics and seat-human system dynamic response are modeled and analyzed, and experiments are conducted to verify the theoretical solutions. Results show that the stiffness of this nonlinear seat suspension...

  1. Modeling and Analysis of Static and Dynamic Characteristics of Nonlinear Seat Suspension for Off-Road Vehicles

    Directory of Open Access Journals (Sweden)

    Zhenhua Yan

    2015-01-01

    Full Text Available Low-frequency vibrations (0.5–5 Hz that harm drivers occur in off-road vehicles. Thus, researchers have focused on finding methods to effectively isolate or control low-frequency vibrations. A novel nonlinear seat suspension structure for off-road vehicles is designed, whose static characteristics and seat-human system dynamic response are modeled and analyzed, and experiments are conducted to verify the theoretical solutions. Results show that the stiffness of this nonlinear seat suspension could achieve real zero stiffness through well-matched parameters, and precompression of the main spring could change the nonlinear seat suspension performance when a driver’s weight changes. The displacement transmissibility curve corresponds with the static characteristic curve of nonlinear suspension, where the middle part of the static characteristic curve is gentler and the resonance frequency of the displacement transmissibility curve and the isolation minimum frequency are lower. Damping should correspond with static characteristics, in which the corresponding suspension damping value should be smaller given a flatter static characteristic curve to prevent vibration isolation performance reduction.

  2. Analysis of Dynamical Characteristic of Piecewise-Nonlinear Asymmetric Hysteretic System Based on Incremental Harmonic Balance Method

    Directory of Open Access Journals (Sweden)

    H. R. Liu

    2015-01-01

    Full Text Available Considering a sort of elastic mass with asymmetric hysteresis characteristic which widespread existing in engineering field, a piecewise-nonlinear dynamical equation, which contains asymmetric hysteretic loop, is established. By using the method of Incremental Harmonic Balance (IHB, the analytic linearized algebraic equation of the system is obtained. On the basis of this algebraic equation, the coefficients of the algebraic expression are figured out by the incremental procedure and the iterative process of the regulated variable. Through the emulation, the amplitude frequency response curve and the relation between the value of the harmonic component and the external excitation are researched; the bistable regions of the bifurcation diagram of the system under the variation of the excitation amplitude are studied. The above results can be used to guide the research of the asymmetric hysteretic system with polynomial expression.

  3. Dynamic evolution characteristics of a fractional order hydropower station system

    Science.gov (United States)

    Gao, Xiang; Chen, Diyi; Yan, Donglin; Xu, Beibei; Wang, Xiangyu

    2018-01-01

    This paper investigates the dynamic evolution characteristics of the hydropower station by introducing the fractional order damping forces. A careful analysis of the dynamic characteristics of the generator shaft system is carried out under different values of fractional order. It turns out the vibration state of the axis coordinates has a certain evolution law with the increase of the fractional order. Significantly, the obtained law exists in the horizontal evolution and vertical evolution of the dynamical behaviors. Meanwhile, some interesting dynamical phenomena were found in this process. The outcomes of this study enrich the nonlinear dynamic theory from the engineering practice of hydropower stations.

  4. Uses And Characteristics Of Dynamic Tradeoff Evaluation

    Science.gov (United States)

    Schwuttke, Ursula M.

    1995-01-01

    Report discusses basic concepts, some applications, and performance characteristics of dynamic tradeoff evaluation (DTE). Basic concepts of DTE also described in "Dynamic Restructuring of Problems in Artificial Intelligence" (NPO-18488). DTE is method of enhancing real-time performance of artificial-intelligence system such as might be used to monitor data from multiple sensors in factory, aircraft, spacecraft, or other complex system of equipment. Report presents evaluation of DTE as applied to spacecraft-monitoring problems.

  5. Dynamical systems of proper characteristic 0

    International Nuclear Information System (INIS)

    Ahmad, K.H.; Hamoui, A.

    1991-07-01

    Flows with orbits of proper characteristics 0 exhibit recurrent behaviour, a feature of basic importance in the description of their dynamics. Here, we analyze flows with such orbits relating them with recurrent flows and with flows that exhibit orbital, Poisson or Lagrange stability. (author). 11 refs

  6. Dynamic characteristics of mirrors' kinematic mount

    International Nuclear Information System (INIS)

    Wu Wenkai; Du Qiang; Li Jingze; Chen Gang; Chen Xiaojuan; Xu Yuanli

    2002-01-01

    Applying exact constrain design principles, kinematic mount for precision positioning large aperture mirrors is designed; theoretical method is introduced to analyze its dynamic characteristics and the result of the experiment for mirrors, stability; accordingly, the methods to improve design are put forward

  7. An Investigation of dynamic characteristics of structures subjected to dynamic load from the viewpoint of design

    International Nuclear Information System (INIS)

    Lee, Hyun Ah; Kim, Yong Il; Park, Gyung Jin; Kang, Byung Soo; Kim, Joo Sung

    2006-01-01

    All the loads in the real world are dynamic loads and structural optimization under dynamic loads is very difficult. Thus the dynamic loads are often transformed to static loads by dynamic factors, which are believed equivalent to the dynamic loads. However, due to the difference of load characteristics, there can be considerable differences between the results from static and dynamic analyses. When the natural frequency of a structure is high, the dynamic analysis result is similar to that of static analysis due to the small inertia effect on the behavior of the structure. However, if the natural frequency of the structure is low, the inertia effect should not be ignored. then, the behavior of the dynamic system is different from that of the static system. The difference of the two cases can be explained from the relationship between the homogeneous and the particular solutions of the differential equation that governs the behavior of the structure. Through various examples, the difference between the dynamic analysis and the static analysis are shown. Also dynamic response optimization results are compared with the results with static loads transformed from dynamic loads by dynamic factors, which show the necessity of the design considering dynamic loads

  8. Fundamental characteristics and simplified evaluation method of dynamic earth pressure

    International Nuclear Information System (INIS)

    Nukui, Y.; Inagaki, Y.; Ohmiya, Y.

    1989-01-01

    In Japan, a method is commonly used in the evaluation of dynamic earth pressure acting on the underground walls of a deeply embedded nuclear reactor building. However, since this method was developed on the basis of the limit state of soil supported by retaining walls, the behavior of dynamic earth pressure acting on the embedded part of a nuclear reactor building may differ from the estimated by this method. This paper examines the fundamental characteristics of dynamic earth pressure through dynamic soil-structure interaction analysis. A simplified method to evaluate dynamic earth pressure for the design of underground walls of a nuclear reactor building is described. The dynamic earth pressure is fluctuating earth pressure during earthquake

  9. Limitations and corrections in measuring dynamic characteristics of structural systems

    International Nuclear Information System (INIS)

    Walter, P.L.

    1978-10-01

    The work deals with limitations encountered in measuring the dynamic characteristics of structural systems. Structural loading and response are measured by transducers possessing multiple resonant frequencies in their transfer function. In transient environments, the resultant signals from these transducers are shown to be analytically unpredictable in amplitude level and frequency content. Data recorded during nuclear effects simulation testing on structures are analyzed. Results of analysis can be generalized to any structure which encounters dynamic loading. Methods to improve the recorded data are described which can be implemented on a frequency selective basis during the measurement process. These improvements minimize data distortion attributable to the transfer characteristics of the measuring transducers

  10. Nonlinear Dynamic Characteristics of the Railway Vehicle

    Science.gov (United States)

    Uyulan, Çağlar; Gokasan, Metin

    2017-06-01

    The nonlinear dynamic characteristics of a railway vehicle are checked into thoroughly by applying two different wheel-rail contact model: a heuristic nonlinear friction creepage model derived by using Kalker 's theory and Polach model including dead-zone clearance. This two models are matched with the quasi-static form of the LuGre model to obtain more realistic wheel-rail contact model. LuGre model parameters are determined using nonlinear optimization method, which it's objective is to minimize the error between the output of the Polach and Kalker model and quasi-static LuGre model for specific operating conditions. The symmetric/asymmetric bifurcation attitude and stable/unstable motion of the railway vehicle in the presence of nonlinearities which are yaw damping forces in the longitudinal suspension system are analyzed in great detail by changing the vehicle speed. Phase portraits of the lateral displacement of the leading wheelset of the railway vehicle are drawn below and on the critical speeds, where sub-critical Hopf bifurcation take place, for two wheel-rail contact model. Asymmetric periodic motions have been observed during the simulation in the lateral displacement of the wheelset under different vehicle speed range. The coexistence of multiple steady states cause bounces in the amplitude of vibrations, resulting instability problems of the railway vehicle. By using Lyapunov's indirect method, the critical hunting speeds are calculated with respect to the radius of the curved track parameter changes. Hunting, which is defined as the oscillation of the lateral displacement of wheelset with a large domain, is described by a limit cycle-type oscillation nature. The evaluated accuracy of the LuGre model adopted from Kalker's model results for prediction of critical speed is higher than the results of the LuGre model adopted from Polach's model. From the results of the analysis, the critical hunting speed must be resolved by investigating the track tests

  11. Bayesian dynamic mediation analysis.

    Science.gov (United States)

    Huang, Jing; Yuan, Ying

    2017-12-01

    Most existing methods for mediation analysis assume that mediation is a stationary, time-invariant process, which overlooks the inherently dynamic nature of many human psychological processes and behavioral activities. In this article, we consider mediation as a dynamic process that continuously changes over time. We propose Bayesian multilevel time-varying coefficient models to describe and estimate such dynamic mediation effects. By taking the nonparametric penalized spline approach, the proposed method is flexible and able to accommodate any shape of the relationship between time and mediation effects. Simulation studies show that the proposed method works well and faithfully reflects the true nature of the mediation process. By modeling mediation effect nonparametrically as a continuous function of time, our method provides a valuable tool to help researchers obtain a more complete understanding of the dynamic nature of the mediation process underlying psychological and behavioral phenomena. We also briefly discuss an alternative approach of using dynamic autoregressive mediation model to estimate the dynamic mediation effect. The computer code is provided to implement the proposed Bayesian dynamic mediation analysis. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  12. Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

    Science.gov (United States)

    The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

  13. Characteristic analysis of servo valve

    International Nuclear Information System (INIS)

    Ko, J. H.; Ryu, D. R.; Lee, J. H.; Kim, Y. S.; Na, J. C.; Kim, D. S.

    2008-01-01

    Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The first objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. And a tester for conducting an overall performance test was designed and manufactured, and as a result of conducting the flow rate test, the pressure test and the frequency test on the developed pneumatic servo valve

  14. 近海风机叶片动力特性分析%Dynamic Characteristics Analysis of the Offshore Wind Turbine Blades

    Institute of Scientific and Technical Information of China (English)

    李静; 陈健云; 陈小波

    2011-01-01

    The topic of offshore wind energy is attracting more and more attention as the energy crisis heightens. The blades are the key components of offshore wind turbines, and their dynamic characteristics directly determine the effectiveness of offshore wind turbines. With different rotating speeds and blade length,the rotating blades generate various centrifugal stiffening effects. To directly analyze the centrifugal stiffening effect of blades, the Rayleigh energy method (REM) was used to derive the natural frequency equation of the blade, including the centrifugal stiffening effect and the axial force calculation formula. The axial force planes and the first to third order natural frequency planes which vary with the rotating speed and length were calculated in three-dimensional coordinates. The centrifugal stiffening coefficient was introduced to quantitatively study the relationship between the centrifugal stiffening degree and the rotating speed, and then the fundamental frequency correction formula was built based on the rotating speed and the blade length. The analysis results show that the calculation results of the fundamental frequency correction formula agree with the theoretical calculation results. The error of calculation results between them is less than 0.5%.

  15. Nonlinear analysis of pupillary dynamics.

    Science.gov (United States)

    Onorati, Francesco; Mainardi, Luca Tommaso; Sirca, Fabiola; Russo, Vincenzo; Barbieri, Riccardo

    2016-02-01

    Pupil size reflects autonomic response to different environmental and behavioral stimuli, and its dynamics have been linked to other autonomic correlates such as cardiac and respiratory rhythms. The aim of this study is to assess the nonlinear characteristics of pupil size of 25 normal subjects who participated in a psychophysiological experimental protocol with four experimental conditions, namely “baseline”, “anger”, “joy”, and “sadness”. Nonlinear measures, such as sample entropy, correlation dimension, and largest Lyapunov exponent, were computed on reconstructed signals of spontaneous fluctuations of pupil dilation. Nonparametric statistical tests were performed on surrogate data to verify that the nonlinear measures are an intrinsic characteristic of the signals. We then developed and applied a piecewise linear regression model to detrended fluctuation analysis (DFA). Two joinpoints and three scaling intervals were identified: slope α0, at slow time scales, represents a persistent nonstationary long-range correlation, whereas α1 and α2, at middle and fast time scales, respectively, represent long-range power-law correlations, similarly to DFA applied to heart rate variability signals. Of the computed complexity measures, α0 showed statistically significant differences among experimental conditions (pnonlinear dynamics, (b) three well-defined and distinct long-memory processes exist at different time scales, and (c) autonomic stimulation is partially reflected in nonlinear dynamics. (c) autonomic stimulation is partially reflected in nonlinear dynamics.

  16. A review of dynamic characteristics of magnetically levitated vehicle systems

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Y.; Chen, S.S.

    1995-11-01

    The dynamic response of magnetically levitated (maglev) ground transportation systems has important consequences for safety and ride quality, guideway design, and system costs. Ride quality is determined by vehicle response and by environmental factors such as humidity and noise. The dynamic response of the vehicles is the key element in determining ride quality, while vehicle stability is an important safety-related element. To design a guideway that provides acceptable ride quality in the stable region, vehicle dynamics must be understood. Furthermore, the trade-off between guideway smoothness and levitation and control systems must be considered if maglev systems are to be economically feasible. The link between the guideway and the other maglev components is vehicle dynamics. For a commercial maglev system, vehicle dynamics must be analyzed and tested in detail. This report, which reviews various aspects of the dynamic characteristics, experiments and analysis, and design guidelines for maglev systems, discusses vehicle stability, motion dependent magnetic force components, guideway characteristics, vehicle/ guideway interaction, ride quality, suspension control laws, aerodynamic loads and other excitations, and research needs.

  17. Dynamic Contingency Analysis Tool

    Energy Technology Data Exchange (ETDEWEB)

    2016-01-14

    The Dynamic Contingency Analysis Tool (DCAT) is an open-platform and publicly available methodology to help develop applications that aim to improve the capabilities of power system planning engineers to assess the impact and likelihood of extreme contingencies and potential cascading events across their systems and interconnections. Outputs from the DCAT will help find mitigation solutions to reduce the risk of cascading outages in technically sound and effective ways. The current prototype DCAT implementation has been developed as a Python code that accesses the simulation functions of the Siemens PSS/E planning tool (PSS/E). It has the following features: It uses a hybrid dynamic and steady-state approach to simulating the cascading outage sequences that includes fast dynamic and slower steady-state events. It integrates dynamic models with protection scheme models for generation, transmission, and load. It models special protection systems (SPSs)/remedial action schemes (RASs) and automatic and manual corrective actions. Overall, the DCAT attempts to bridge multiple gaps in cascading-outage analysis in a single, unique prototype tool capable of automatically simulating and analyzing cascading sequences in real systems using multiprocessor computers.While the DCAT has been implemented using PSS/E in Phase I of the study, other commercial software packages with similar capabilities can be used within the DCAT framework.

  18. The spatiotemporal dynamic analysis of the implied market information and characteristics of the correlation coefficient matrix of the international crude oil price returns

    International Nuclear Information System (INIS)

    Tian, Lixin; Ding, Zhenqi; Zhen, Zaili; Wang, Minggang

    2016-01-01

    The international crude oil market plays a crucial role in economies, and the studies of the correlation, risk and synchronization of the international crude oil market have important implications for the security and stability of the country, avoidance of business risk and people's daily lives. We investigate the information and characteristics of the international crude oil market (1999-2015) based on the random matrix theory (RMT). Firstly, we identify richer information in the largest eigenvalues deviating from RMT predictions for the international crude oil market; the international crude oil market can be roughly divided into ten different periods by the methods of eigenvectors and characteristic combination, and the implied market information of the correlation coefficient matrix is advanced. Secondly, we study the characteristics of the international crude oil market by the methods of system risk entropy, dynamic synchronous ratio, dynamic non-synchronous ratio and dynamic clustering algorithm. The results show that the international crude oil market is full of risk. The synchronization of the international crude oil market is very strong, and WTI and Brent occupy a very important position in the international crude oil market. (orig.)

  19. The spatiotemporal dynamic analysis of the implied market information and characteristics of the correlation coefficient matrix of the international crude oil price returns

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Lixin [Jiangsu University, Energy Development and Environmental Protection Strategy Research Center, Zhenjiang, Jiangsu (China); Nanjing Normal University, School of Mathematical Sciences, Nanjing, Jiangsu (China); Ding, Zhenqi; Zhen, Zaili [Jiangsu University, Energy Development and Environmental Protection Strategy Research Center, Zhenjiang, Jiangsu (China); Wang, Minggang [Nanjing Normal University, School of Mathematical Sciences, Nanjing, Jiangsu (China)

    2016-08-15

    The international crude oil market plays a crucial role in economies, and the studies of the correlation, risk and synchronization of the international crude oil market have important implications for the security and stability of the country, avoidance of business risk and people's daily lives. We investigate the information and characteristics of the international crude oil market (1999-2015) based on the random matrix theory (RMT). Firstly, we identify richer information in the largest eigenvalues deviating from RMT predictions for the international crude oil market; the international crude oil market can be roughly divided into ten different periods by the methods of eigenvectors and characteristic combination, and the implied market information of the correlation coefficient matrix is advanced. Secondly, we study the characteristics of the international crude oil market by the methods of system risk entropy, dynamic synchronous ratio, dynamic non-synchronous ratio and dynamic clustering algorithm. The results show that the international crude oil market is full of risk. The synchronization of the international crude oil market is very strong, and WTI and Brent occupy a very important position in the international crude oil market. (orig.)

  20. Dynamic characteristics of nanoindentation using atomistic simulation

    International Nuclear Information System (INIS)

    Fang, Te-Hua; Chang, Wen-Yang; Huang, Jian-Jin

    2009-01-01

    Atomistic simulations are used to investigate how the nanoindentation mechanism influences dislocation nucleation under molecular dynamic behavior on the aluminum (0 0 1) surface. The characteristics of molecular dynamics in terms of various nucleation criteria are explored, including various molecular models, a multi-step load/unload cycle, deformation mechanism of atoms, tilt angle of the indenter, and slip vectors. Simulation results show that both the plastic energy and the adhesive force increase with increasing nanoindentation depths. The maximum forces for all indentation depths decrease with increasing multi-step load/unload cycle time. Dislocation nucleation, gliding, and interaction occur along Shockley partials on (1 1 1) slip planes. The indentation force applied along the normal direction, a tilt angle of 0 o , is smaller than the force component that acts on the surface atoms. The corresponding slip vector of the atoms in the (1 1 1) plane has low-energy sessile stair-rod dislocations in the pyramid of intrinsic stacking faults.

  1. Dynamic characteristics of nanoindentation using atomistic simulation

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Te-Hua, E-mail: fang.tehua@msa.hinet.net [Institute of Mechanical and Electromechanical Engineering, National Formosa University, Yunlin 632, Taiwan (China); Chang, Wen-Yang [Microsystems Technology Center, Industrial Technology Research Institute, Tainan 709, Taiwan (China); Huang, Jian-Jin [Institute of Mechanical and Electromechanical Engineering, National Formosa University, Yunlin 632, Taiwan (China)

    2009-06-15

    Atomistic simulations are used to investigate how the nanoindentation mechanism influences dislocation nucleation under molecular dynamic behavior on the aluminum (0 0 1) surface. The characteristics of molecular dynamics in terms of various nucleation criteria are explored, including various molecular models, a multi-step load/unload cycle, deformation mechanism of atoms, tilt angle of the indenter, and slip vectors. Simulation results show that both the plastic energy and the adhesive force increase with increasing nanoindentation depths. The maximum forces for all indentation depths decrease with increasing multi-step load/unload cycle time. Dislocation nucleation, gliding, and interaction occur along Shockley partials on (1 1 1) slip planes. The indentation force applied along the normal direction, a tilt angle of 0{sup o}, is smaller than the force component that acts on the surface atoms. The corresponding slip vector of the atoms in the (1 1 1) plane has low-energy sessile stair-rod dislocations in the pyramid of intrinsic stacking faults.

  2. Study on the Fire Damage Characteristics of the New Qidaoliang Highway Tunnel: Field Investigation with Computational Fluid Dynamics (CFD) Back Analysis.

    Science.gov (United States)

    Lai, Hongpeng; Wang, Shuyong; Xie, Yongli

    2016-10-15

    In the New Qidaoliang Tunnel (China), a rear-end collision of two tanker trunks caused a fire. To understand the damage characteristics of the tunnel lining structure, in situ investigation was performed. The results show that the fire in the tunnel induced spallation of tunnel lining concrete covering 856 m³; the length of road surface damage reached 650 m; the sectional area had a maximum 4% increase, and the mechanical and electrical facilities were severely damaged. The maximum area loss happened at the fire spot with maximum observed concrete spallation up to a thickness of 35.4 cm. The strength of vault and side wall concrete near the fire source was significantly reduced. The loss of concrete strength of the side wall near the inner surface of tunnel was larger than that near the surrounding rock. In order to perform back analysis of the effect of thermal load on lining structure, simplified numerical simulation using computational fluid dynamics (CFD) was also performed, repeating the fire scenario. The simulated results showed that from the fire breaking out to the point of becoming steady, the tunnel experienced processes of small-scale warming, swirl around fire, backflow, and longitudinal turbulent flow. The influence range of the tunnel internal temperature on the longitudinal downstream was far greater than on the upstream, while the high temperature upstream and downstream of the transverse fire source mainly centered on the vault or the higher vault waist. The temperature of each part of the tunnel near the fire source had no obvious stratification phenomenon. The temperature of the vault lining upstream and downstream near the fire source was the highest. The numerical simulation is found to be in good agreement with the field observations.

  3. Evaluating the Dynamic Characteristics of Retrofitted RC Beams

    International Nuclear Information System (INIS)

    Ghods, Amir S.; Esfahani, Mohamad R.; Moghaddasie, Behrang

    2008-01-01

    The aim of this experimental study was to investigate the relationship between the damage and changes in dynamic characteristics of reinforced concrete members strengthened with Carbon Fiber Reinforced Polymer (CFRP). Modal analysis is a popular non-destructive method for evaluating health of structural systems. A total of 8 reinforced concrete beams with similar dimensions were made using concrete with two different compressive strengths and reinforcement ratios. Monotonic loading was applied with four-point-bending setup in order to generate different damage levels in the specimens while dynamic testing was conducted to monitor the changes in dynamic characteristics of the specimens. In order to investigate the effect of CFRP on static and dynamic properties of specimens, some of the beams were loaded to half of their ultimate load carrying capacity and then were retrofitted using composite laminates with different configuration. Retrofitted specimens demonstrated elevated load carrying capacity, higher flexural stiffness and lower displacement ductility. By increasing the damage level in specimens, frequencies of the beams were decreased and after strengthening these values were improved significantly. The intensity of the damage level in each specimen affects the shape of its mode as well. Fixed points and curvatures of mode shapes of beams tend to move toward the location of the damage in each case

  4. Dynamic Characteristics of Buildings from Signal Processing of Ambient Vibration

    Science.gov (United States)

    Dobre, Daniela; Sorin Dragomir, Claudiu

    2017-10-01

    The experimental technique used to determine the dynamic characteristics of buildings is based on records of low intensity oscillations of the building produced by various natural factors, such as permanent agitation type microseismic motions, city traffic, wind etc. The possibility of recording these oscillations is provided by the latest seismic stations (Geosig and Kinemetrics digital accelerographs). The permanent microseismic agitation of the soil is a complex form of stationary random oscillations. The building filters the soil excitation, selects and increases the components of disruptive vibrations corresponding to its natural vibration periods. For some selected buildings, with different instrumentation schemes for the location of sensors (in free-field, at basement, ground floor, roof level), a correlation between the dynamic characteristics resulted from signal processing of ambient vibration and from a theoretical analysis will be presented. The interpretation of recording results could highlight the behavior of the whole structure. On the other hand, these results are compared with those from strong motions, or obtained from a complex dynamic analysis, and they are quite different, but they are explicable.

  5. Global Analysis of Nonlinear Dynamics

    CERN Document Server

    Luo, Albert

    2012-01-01

    Global Analysis of Nonlinear Dynamics collects chapters on recent developments in global analysis of non-linear dynamical systems with a particular emphasis on cell mapping methods developed by Professor C.S. Hsu of the University of California, Berkeley. This collection of contributions prepared by a diverse group of internationally recognized researchers is intended to stimulate interests in global analysis of complex and high-dimensional nonlinear dynamical systems, whose global properties are largely unexplored at this time. This book also: Presents recent developments in global analysis of non-linear dynamical systems Provides in-depth considerations and extensions of cell mapping methods Adopts an inclusive style accessible to non-specialists and graduate students Global Analysis of Nonlinear Dynamics is an ideal reference for the community of nonlinear dynamics in different disciplines including engineering, applied mathematics, meteorology, life science, computational science, and medicine.  

  6. Dynamical characteristics of the seasonal circulations over the Korea peninsula

    International Nuclear Information System (INIS)

    1989-10-01

    This paper reports dynamical characteristics of the seasonal circulations over the Korean peninsula. It consists of summary, research method, result, consideration and conclusion. It introduces the method of research ; characteristics of circulation over seasonal wind in Asia, characteristic of upper jet stream related cold wave and monsoon in East Asia and dynamics of pulsation and maintain of high atmospheric pressure in siberia in winter. It was reported by Korea science foundation in 1989.

  7. Belt Conveyor Dynamic Characteristics and Influential Factors

    Directory of Open Access Journals (Sweden)

    Junxia Li

    2018-01-01

    Full Text Available This paper uses the Kelvin-Voigt viscoelastic model to establish the continuous dynamic equations for tail hammer tension belt conveyors. The viscoelastic continuity equations are solved using the generalized coordinate method. We analyze various factors influencing longitudinal vibration of the belt conveyor by simulation and propose a control strategy to limit the vibration. The proposed approach and control strategy were verified by several experimental researches and cases. The proposed approach provides improved accuracy for dynamic design of belt conveyors.

  8. Dynamic characteristics of lead rubber bearings with dynamic two-dimensional test equipment

    International Nuclear Information System (INIS)

    Ohtori, Y.; Ishida, K.; Mazda, T.

    1994-01-01

    Although studies have previously been done on the static mechanical properties of lead rubber bearings, this study aims to grasp the dynamic characteristics of lead rubber bearings from experimental results, using two-dimensional dynamic test equipment which is designed to grasp in detail such dynamic characteristics as deformation capacity and proof stress. This paper describes the results from three types of tests: (1) dynamic mechanical properties tests, (2) cyclic loading tests, and (3) dynamic ultimate tests. Through these tests, it was confirmed that the dynamic characteristics of lead rubber bearings are independent of strain rate

  9. Dynamic characteristics of rocks and method of their determine

    OpenAIRE

    Radoslav Schügerl

    2009-01-01

    This paper presents selected problems of the research of the influence of technical vibrations on rocks. The vibrations are the products of the technological procedure, such as mining blasting, ramming of the piles, using of the drilling-equipment or vibration machines. The vibrations could be also evocated by road or train traffic. The most important dynamic characteristics of rocks are dynamic modulus of elasticity Edyn; dynamic modulus of deformation Edef, dyn; dynamic shear-modulus Gdyn; ...

  10. Simulation and Experimental Investigation of Structural Dynamic Frequency Characteristics Control

    Directory of Open Access Journals (Sweden)

    Bing Li

    2012-04-01

    Full Text Available In general, mechanical equipment such as cars, airplanes, and machine tools all operate with constant frequency characteristics. These constant working characteristics should be controlled if the dynamic performance of the equipment demands improvement or the dynamic characteristics is intended to change with different working conditions. Active control is a stable and beneficial method for this, but current active control methods mainly focus on vibration control for reducing the vibration amplitudes in the time domain or frequency domain. In this paper, a new method of dynamic frequency characteristics active control (DFCAC is presented for a flat plate, which can not only accomplish vibration control but also arbitrarily change the dynamic characteristics of the equipment. The proposed DFCAC algorithm is based on a neural network including two parts of the identification implement and the controller. The effectiveness of the DFCAC method is verified by several simulation and experiments, which provide desirable results.

  11. Operational Dynamic Configuration Analysis

    Science.gov (United States)

    Lai, Chok Fung; Zelinski, Shannon

    2010-01-01

    Sectors may combine or split within areas of specialization in response to changing traffic patterns. This method of managing capacity and controller workload could be made more flexible by dynamically modifying sector boundaries. Much work has been done on methods for dynamically creating new sector boundaries [1-5]. Many assessments of dynamic configuration methods assume the current day baseline configuration remains fixed [6-7]. A challenging question is how to select a dynamic configuration baseline to assess potential benefits of proposed dynamic configuration concepts. Bloem used operational sector reconfigurations as a baseline [8]. The main difficulty is that operational reconfiguration data is noisy. Reconfigurations often occur frequently to accommodate staff training or breaks, or to complete a more complicated reconfiguration through a rapid sequence of simpler reconfigurations. Gupta quantified a few aspects of airspace boundary changes from this data [9]. Most of these metrics are unique to sector combining operations and not applicable to more flexible dynamic configuration concepts. To better understand what sort of reconfigurations are acceptable or beneficial, more configuration change metrics should be developed and their distribution in current practice should be computed. This paper proposes a method to select a simple sequence of configurations among operational configurations to serve as a dynamic configuration baseline for future dynamic configuration concept assessments. New configuration change metrics are applied to the operational data to establish current day thresholds for these metrics. These thresholds are then corroborated, refined, or dismissed based on airspace practitioner feedback. The dynamic configuration baseline selection method uses a k-means clustering algorithm to select the sequence of configurations and trigger times from a given day of operational sector combination data. The clustering algorithm selects a simplified

  12. Dynamic Characteristics of Steam Generator Tubes with Defect due to Wear

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sangjin; Rhee, Huinam [Sunchon National Univ., Sunchon (Korea, Republic of); Yoon, Doo Byung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    These defects may affect the dynamic characteristics of tubes, and therefore, the vibrational behavior of the tube due to flow-induced loads can be varied. Change in the vibrational response of a tube may result in different wear characteristics from the design condition, which must be checked for both safety and economic point of view. This paper deals with the study on the effect of wears or cracks on the dynamic characteristics of steam generator tubes using finite element analysis. In this paper the effect of defects on the surface due to wear on the variation of dynamic characteristics of steam generator tubes was studied using the finite element analysis. The changes of natural frequencies and mode shapes can directly affect the flow-induced vibration response characteristics, therefore, they must be evaluated appropriately. The results in this study can be a good basis to estimate the FIV characteristics of the steam generator tubes having defects such as wear or crack.

  13. Strength and dynamic characteristics analyses of wound composite axial impeller

    Science.gov (United States)

    Wang, Jifeng; Olortegui-Yume, Jorge; Müller, Norbert

    2012-03-01

    A low cost, light weight, high performance composite material turbomachinery impeller with a uniquely designed blade patterns is analyzed. Such impellers can economically enable refrigeration plants to use water as a refrigerant (R718). A strength and dynamic characteristics analyses procedure is developed to assess the maximum stresses and natural frequencies of these wound composite axial impellers under operating loading conditions. Numerical simulation using FEM for two-dimensional and three-dimensional impellers was investigated. A commercially available software ANSYS is used for the finite element calculations. Analysis is done for different blade geometries and then suggestions are made for optimum design parameters. In order to avoid operating at resonance, which can make impellers suffer a significant reduction in the design life, the designer must calculate the natural frequency and modal shape of the impeller to analyze the dynamic characteristics. The results show that using composite Kevlar fiber/epoxy matrix enables the impeller to run at high tip speed and withstand the stresses, no critical speed will be matched during start-up and shut-down, and that mass imbalances of the impeller shall not pose a critical problem.

  14. A study on the dynamic characteristics of pump seal, 2

    International Nuclear Information System (INIS)

    Yang, Bosuk; Iwatsubo, Takuzo; Kawai, Ryoji

    1984-01-01

    From the viewpoint of the rate of plant operation, the vibration problems of pumps have been resolved. Owing to the trend toward high speed and large capacity, the flow of liquid films in the bearings and seals of pumps changed from laminar to turbulent flow, and also the effect of the inertia force of liquid films arose, the dynamic characteristics of high pressure non-contact seals due to fluid force have become to exert important effect on the vibration of pump shafts. In this research, the authors analyzed the dynamic characteristics of a seal due to fluid force when the parallel grooves with rectangular sectional form are made on the circumference of a journal. The equations of motion and the method of analysis, and the example of numerical calculation are reported. For determining the fluid force in a seal when parallel grooves exist, the method of dividing the seal into rands and grooves, determining the fluid force on a rand and in a groove successively for each stage, and summing all up is shown. The compound damping coefficient, added mass coefficient, compound spring coefficient, spring coefficient and damping coefficient were affected by the length of groove part and the Reynolds number in circumferential and axial directions. (Kako, I.)

  15. Modeling the dynamic characteristics of pneumatic muscle.

    Science.gov (United States)

    Reynolds, D B; Repperger, D W; Phillips, C A; Bandry, G

    2003-03-01

    A pneumatic muscle (PM) system was studied to determine whether a three-element model could describe its dynamics. As far as the authors are aware, this model has not been used to describe the dynamics of PM. A new phenomenological model consists of a contractile (force-generating) element, spring element, and damping element in parallel. The PM system was investigated using an apparatus that allowed precise and accurate actuation pressure (P) control by a linear servo-valve. Length change of the PM was measured by a linear potentiometer. Spring and damping element functions of P were determined by a static perturbation method at several constant P values. These results indicate that at constant P, PM behaves as a spring and damper in parallel. The contractile element function of P was determined by the response to a step input in P, using values of spring and damping elements from the perturbation study. The study showed that the resulting coefficient functions of the three-element model describe the dynamic response to the step input of P accurately, indicating that the static perturbation results can be applied to the dynamic case. This model is further validated by accurately predicting the contraction response to a triangular P waveform. All three elements have pressure-dependent coefficients for pressure P in the range 207 < or = P < or = 621 kPa (30 < or = P < or = 90 psi). Studies with a step decrease in P (relaxation of the PM) indicate that the damping element coefficient is smaller during relaxation than contraction.

  16. Belt Conveyor Dynamic Characteristics and Influential Factors

    OpenAIRE

    Li, Junxia; Pang, Xiaoxu

    2018-01-01

    This paper uses the Kelvin-Voigt viscoelastic model to establish the continuous dynamic equations for tail hammer tension belt conveyors. The viscoelastic continuity equations are solved using the generalized coordinate method. We analyze various factors influencing longitudinal vibration of the belt conveyor by simulation and propose a control strategy to limit the vibration. The proposed approach and control strategy were verified by several experimental researches and cases. The proposed a...

  17. Research on Dynamic Coupled Characteristics of A Tracked Vehicle Gearbox

    Directory of Open Access Journals (Sweden)

    Hui Liu

    2011-12-01

    Full Text Available A tracked vehicle gearbox is divided into two subsystems-housing and gear train. Dynamic behaviors of the two subsystems are coupled practically. And the coupled characteristics describe the integrative dynamic behaviors of gearbox. This study proposes a coupled simulation model to investigate the interrelationship between dynamics of two subsystems. Multi-source excitations are numerically calculated to provide boundary conditions. The flexibility of transmission shafts and housing is mathematically described based on mode superposition. The coupled dynamic characteristics are analyzed with dynamics simulation computation. The flexibility of housing is one of the main causes to induce the fluctuation of dynamic responses of transmission shafts. The experimental results show that the proposed method is accurate through comparison of simulation results and test data.

  18. Dynamic Characteristic Analysis of High-speed Spherical Ball Bearing%高速滚珠关节轴承的动力学特性分析

    Institute of Scientific and Technical Information of China (English)

    卓耀彬; 周晓军

    2015-01-01

    The dynamics balance equation of spherical ball bearing under combined loads and high-speed revolution condition is established, during using the outer ring raceway control theory, considering the influence of ball's gyroscopic couple and centrifugal force, and analyzing several factors, such as overall force balance of spherical ball bearing, relationship of geometric structure, curvature of contact point, change of contact angle, relationship of elastic deformation, rotation and revolution of ball, force balance of ball, etc. After analyzing the solution method of the dynamics balance equation, obtaining the change rules of the unknown variables’ feasible regions, and setting up the optimization objective equations, solving method and procedure of optimization equation basing on the complex-constrain genetic algorithm is presented. As an example of spherical bearing BRF30, its dynamics balance equation is established and solved, the change laws of several important bearing statuses are obtained, such as relative displacement between inner ring and outer ring, stiffness of bearing, contact angle, distribution of contact angle, distribution of loads, ratio of revolution, etc. The research provides theoretical basis for designing and analyzing of the bearing, such as standardization of its structural size parameters and characteristic parameters, calculations of equivalent loads and work life, optimal design, etc.%应用外圈滚道控制理论,考虑滚珠陀螺力矩和离心力的影响,分析高速滚珠关节轴承的整体受力平衡、结构尺寸关系、接触点的综合曲率、接触角的变化、弹性变形关系、滚珠的自转和公转、滚珠受力平衡等因素,建立滚珠关节轴承在联合载荷及高速旋转工况下的动力学平衡方程。对动力学平衡方程的求解方法进行分析,得到未知变量可行域的变化规律,建立优化目标方程,提出基于复合形法约束处理遗传算法的优化方

  19. Static Analysis of Dynamic Languages

    DEFF Research Database (Denmark)

    Madsen, Magnus

    Dynamic programming languages are highly popular and widely used. Java- Script is often called the lingua franca of the web and it is the de facto standard for client-side web programming. On the server-side the PHP, Python and Ruby languages are prevalent. What these languages have in common...... with static type systems, such as Java and C# , but the same features are rarely available for dynamic languages such as JavaScript. The aim of this thesis is to investigate techniques for improving the tool- support for dynamic programming languages without imposing any artificial restrictions...... of new dataflow analysis techniques to tackle the nature of dynamic programming languages....

  20. Dynamic Characteristics of Magneto-Fluid Supports

    Directory of Open Access Journals (Sweden)

    V. A. Chernobai

    2008-01-01

    Full Text Available The paper considers a vibro-protective magneto-fluid support that uses elastic properties of magnetic fluid with a free surface in magnetic field.The paper has experimentally revealed that the analyzed structure is characterized by better noise absorbing characteristics.The conducted experiments have made it possible to conclude that there is a possibility to use vibro-protective magneto-fluid supports within the frequency range from 0 to 300 Hz, amplitudes up to 2 mm and unit load up to 2,5 · 10 4 Н/м².

  1. Principle component analysis (PCA) for investigation of relationship between population dynamics of microbial pathogenesis, chemical and sensory characteristics in beef slices containing Tarragon essential oil.

    Science.gov (United States)

    Alizadeh Behbahani, Behrooz; Tabatabaei Yazdi, Farideh; Shahidi, Fakhri; Mortazavi, Seyed Ali; Mohebbi, Mohebbat

    2017-04-01

    Principle component analysis (PCA) was employed to examine the effect of the exerted treatments on the beef shelf life as well as discovering the correlations between the studied responses. Considering the variability of the dimensions of the responses, correlation coefficients were applied to form the matrix and extract the eigenvalue. Antimicrobial effect was evaluated on 10 pathogenic microorganisms through the methods of hole-plate diffusion method, disk diffusion method, pour plate method, minimum inhibitory concentration and minimum bactericidal/fungicidal concentration. Antioxidant potential and total phenolic content were examined through the method of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Folin-Ciocalteu method, respectively. The components were identified through gas chromatography and gas chromatography/mass spectrometry. Barhang seed mucilage (BSM) based edible coating containing 0, 0.5, 1 and 1.5% (w/w) Tarragon (T) essential oil mix were applied on beef slices to control the growth of pathogenic microorganisms. Microbiological (total viable count, psychrotrophic count, Escherichia coli, Staphylococcus aureus and fungi), chemical (thiobarbituric acid, peroxide value and pH) and sensory characteristics (odor, color and overall acceptability) analysis measurements were made during the storage periodically. PCA was employed to examine the effect of the exerted treatments on the beef shelf life as well as discovering the correlations between the studied responses. Considering the variability of the dimensions of the responses, correlation coefficients were applied to form the matrix and extract the eigenvalue. The PCA showed that the properties of the uncoated meat samples on the 9th, 12th, 15th and 18th days of storage are continuously changing independent of the exerted treatments on the other samples. This reveals the effect of the exerted treatments on the samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Physical characteristics of cometary dust from dynamical studies - A review

    Science.gov (United States)

    Sekanina, Z.

    1980-01-01

    Progress made in the determination of the physical characteristics of cometary dust particles from studies of dust tail dynamics is reviewed. Applications of the combined dynamical photometric approach of Finson and Probstein (1968) to studies of cometary tails exhibiting continuous light intensity variations are discussed, with attention given to determinations of the particle-size-related distribution function of the solar radiation pressure exerted on the particles, the contribution of comets to the interplanetary dust, calculations of dust ejection rates and a Monte Carlo approach to the analysis of dust tails. Investigations of dust streamers and striae, which are believed to be related to comet outbursts entailing brief but sharp enhancements of dust production, are then reviewed, with particular attention given to observations of Comet West 1976 VI. Finally, the question of cometary particle type is addressed, and it is pointed out that the presence of submicron absorbing particles in the striae of Comet West is not incompatible with the presence of micron-size dielectric particles in the inner coma.

  3. Dynamic stimulated Brillouin scattering analysis

    DEFF Research Database (Denmark)

    Djupsöbacka, A.; Jacobsen, Gunnar; Tromborg, Bjarne

    2000-01-01

    We present a new simple analysis - including the effect of spontaneous emission - of the (dynamic) influence of SBS on the detected receiver eye diagram. It applies in principle for general types of modulation formats such as the digital formats of ASK, FSK, and PSK. The analysis is formulated fo...

  4. Enabling dynamics in face analysis

    NARCIS (Netherlands)

    Dibeklioğlu, H.

    2014-01-01

    Most of the approaches in automatic face analysis rely solely on static appearance. However, temporal analysis of expressions reveals interesting patterns. For a better understanding of the human face, this thesis focuses on temporal changes in the face, and dynamic patterns of expressions. In

  5. Transnational Chinese Sphere in Singapore: Dynamics, Transformations and Characteristics

    Directory of Open Access Journals (Sweden)

    Hong Liu

    2012-01-01

    Full Text Available Based upon an empirical analysis of Singaporean Chinese’s intriguing and changing linkages with China over the past half century, this paper suggests that multi-layered interactions between the Chinese diaspora and the homeland have led to the formulation of an emerging transnational Chinese social sphere, which has three main characteristics: First, it is a space for communication by ethnic Chinese abroad with their hometown/ homeland through steady and extensive flows of people, ideas, goods and capital that transcend the nation-state borders, although states also play an important role in shaping the nature and characteristics of these flows. Second, this transnational social sphere constitutes a dynamic interface between economy, politics and culture, which has contributed to creating a collective diasporic identity as well as social and business networks. Third, the key institutional mechanism of the transnational social sphere is various types of Chinese organizations – ranging from hometown associations to professional organizations – which serve as integral components of Chinese social and business networks.

  6. Corroboration of dynamic characteristics of FBR main vessels by pseudo-dynamic and dynamic buckling experiments

    International Nuclear Information System (INIS)

    Kokubo, K.; Nakagawa, M.; Kawamoto, Y.; Murakami, T.; Matuura, S.; Hagiwara, Y.

    1991-01-01

    Shaking table tests for small-scale models and pseudo-dynamic buckling tests for moderate-scale models are conducted in order to investigate nonlinear pre- and post-buckling characteristics of fast breeder reactor vessels under the seismic lateral load. Two types of ground acceleration waves are used in the experiments. Nonlinear one-degree-of-freedom numerical simulations are also conducted using the hysteresis rules obtained by the tests. Good agreements are obtained between the experiments and calculations. The design method for vessels based on the estimation of nonlinear buckling behaviors is considered. (author)

  7. INVESTIGATION OF DYNAMIC CHARACTERISTICS OF GONDOLA CARS ON PERSPECTIVE BOGIES

    Directory of Open Access Journals (Sweden)

    S. V. Myamlin

    2014-10-01

    Full Text Available Purpose. In this paper, it is necessary to examine the dynamic properties of the gondola car with bogies, model 18-1711 when it moves on straight and curved sections of a track. Methodology. The calculations were performed using the object-oriented programming on the program "Dynamics of Rail Vehicles" ("DYNRAIL" Myamlin S.V. registered 20.03.2003. Mathematical models of a gondola car and bogies 18-100 and 18-711 were created for the calculations. Findings. Dynamic performances comparison of the gondola car with bogies 18-1711 and the gondola car with bogies 18-100, obtained by calculation method was carried out. Originality. Firstly calculations in order to determine the dynamic properties of the gondola car with bogies 18-1711 when it moves on straight and curved sections of track were performed. At the same time an assessment of the dynamic characteristics of the gondola car was made. The following dynamic standards were determined: the coefficient of vertical dynamics (Cdv, the coefficient of horizontal dynamics (Cdh, and the safety factor against derailment (SFd. Track irregularities in vertical and horizontal transverse planes were assigned as perturbations. They should be so that the dynamic indexes of the widely used in operation gondola car on bogies model 18-100 keep in admissible range of speeds up to 80km / h for the empty gondola car and at speeds up to 90km / h for the loaded gondola cars. Practical value. As a result of the calculations and comparisons of their results, we have findings that the use of bogies with bilinear characteristic of the central suspension will improve the dynamic performances of gondola cars, currently operating on bogies, model 18-100. And by improving the dynamic performances it is possible to increase the permissible speeds of these cars motion.

  8. Characteristics and dynamics of the family of talented adolescents

    OpenAIRE

    Ferreira,Jane Farias Chagas; Fleith,Denise de Sousa

    2012-01-01

    The purpose of this study was to describe family characteristics and dynamics of talented adolescents. Forty-two adolescents between 12 and 18 years old who attended a program for gifted students and their family participated in the data collection. A family characteristics questionnaire and the Parent Success Indicator Inventory, children's and parents' versions were used as instruments. The results indicated that more than half of the families with talented adolescents had a traditional fig...

  9. INVESTIGATION OF DYNAMIC CHARACTERISTICS OF ELEMENTS OF AUTOMATICS OF A SMART HOUSE IN PARAMETRICAL STRUCTURAL SCHEMES

    Directory of Open Access Journals (Sweden)

    Petrova Irina Yur’evna

    2018-01-01

    Full Text Available Subject: automation of calculation of dynamic characteristics of the device being designed in the system of conceptual design of sensor equipment, structurally-parametric models of dynamic processes and algorithms for the automated calculation of the qualitative characteristics of elements of the information-measuring and control systems (IMCS. The stage of conceptual design most fully determines the operational characteristics of technical systems. However, none of the information support systems of this stage provides an opportunity to evaluate the performance characteristics of the element being designed taking into account its dynamic characteristics. Research objectives: increasing the effectiveness of the evaluation of dynamic characteristics of sensitive elements of the information-measuring and control systems of a smart house. Materials and methods: when solving the problems posed, the mathematical apparatus of system modeling was used (in particular, the energy-information method of modeling processes of various physical nature that occur in the sensor equipment; the main provisions of the theory of automatic control, the theory of constructing computer-aided design systems, the theory of operational calculus; basics of conceptual design of elements of the information-measuring and control systems. Results: we compared the known automated systems for conceptual design of sensors, highlighted their advantages and disadvantages and we showed that none of these systems allows us to investigate dynamic characteristics of the element being designed in a simple and understandable for engineer form. The authors proposed using energy-information method of modeling for the synthesis of operation principles of sensors and analysis of their dynamic characteristics. We considered elementary dynamic chains and issues of synthesis of parametrical structural schemes that reflect the dynamics of the process with the use of mathematical apparatus of

  10. Dynamic-Stability Characteristics of Premixed Methane Oxy-Combustion

    KAUST Repository

    Shroll, Andrew P.; Shanbhogue, Santosh J.; Ghoniem, Ahmed F.

    2012-01-01

    This work explores the dynamic stability characteristics of premixed CH 4/O 2/CO 2 mixtures in a 50 kW swirl stabilized combustor. In all cases, the methane-oxygen mixture is stoichiometric, with different dilution levels of carbon dioxide used

  11. Dynamic characteristics of polymer faced tilting pad journal bearings

    DEFF Research Database (Denmark)

    Simmons, Gregory F.; Cerda Varela, Alejandro Javier; Santos, Ilmar

    2014-01-01

    Dynamic characteristics of polymer faced tilting pad journal bearings are presented. Investigations are conducted using a single pad, load on pad configuration over a range of shaft speeds and loads. Two polyether ether ketone (PEEK) faced pads, one polytetrafluoroethylene (PTFE) faced pad and two...

  12. Adaptive pseudolinear compensators of dynamic characteristics of automatic control systems

    Science.gov (United States)

    Skorospeshkin, M. V.; Sukhodoev, M. S.; Timoshenko, E. A.; Lenskiy, F. V.

    2016-04-01

    Adaptive pseudolinear gain and phase compensators of dynamic characteristics of automatic control systems are suggested. The automatic control system performance with adaptive compensators has been explored. The efficiency of pseudolinear adaptive compensators in the automatic control systems with time-varying parameters has been demonstrated.

  13. Static Analysis for Dynamic XML

    DEFF Research Database (Denmark)

    Christensen, Aske Simon; Møller, Anders; Schwartzbach, Michael Ignatieff

    2002-01-01

    We describe the summary graph lattice for dataflow analysis of programs that dynamically construct XML documents. Summary graphs have successfully been used to provide static guarantees in the JWIG language for programming interactive Web services. In particular, the JWIG compiler is able to check...

  14. Study on dynamic lifting characteristics of control rod drive mechanism

    International Nuclear Information System (INIS)

    Shen Xiaoyao

    2012-01-01

    Based on the equations of the electric circuit and the magnetic circuit and analysis of the dynamic lifting process for the control rod drive mechanism (CRDM), coupled magnetic-electric-mechanical equations both for the static status and the dynamic status are derived. The analytical method is utilized to obtain the current and the time when the lift starts. The numerical simulation method of dynamic analysis recommended by ASME Code is utilized to simulate the dynamic lifting process of CRDM, and the dynamic features of the system with different design gaps are studied. Conclusions are drawn as: (1) the lifting-start time increases with the design gap, and the time for the lifting process is longer with larger gaps; (2) the lifting velocity increases with time; (3) the lifting acceleration increases with time, and with smaller gaps, the impact acceleration is larger. (author)

  15. Dynamic characteristic of electromechanical coupling effects in motor-gear system

    Science.gov (United States)

    Bai, Wenyu; Qin, Datong; Wang, Yawen; Lim, Teik C.

    2018-06-01

    Dynamic characteristics of an electromechanical model which combines a nonlinear permeance network model (PNM) of a squirrel-cage induction motor and a coupled lateral-torsional dynamic model of a planetary geared rotor system is analyzed in this study. The simulations reveal the effects of internal excitations or parameters like machine slotting, magnetic saturation, time-varying mesh stiffness and shaft stiffness on the system dynamics. The responses of the electromechanical system with PNM motor model are compared with those responses of the system with dynamic motor model. The electromechanical coupling due to the interactions between the motor and gear system are studied. Furthermore, the frequency analysis of the electromechanical system dynamic characteristics predicts an efficient way to detect work condition of unsymmetrical voltage sag.

  16. Essentials of applied dynamic analysis

    CERN Document Server

    Jia, Junbo

    2014-01-01

    This book presents up-to-date knowledge of dynamic analysis in engineering world. To facilitate the understanding of the topics by readers with various backgrounds, general principles are linked to their applications from different angles. Special interesting topics such as statistics of motions and loading, damping modeling and measurement, nonlinear dynamics, fatigue assessment, vibration and buckling under axial loading, structural health monitoring, human body vibrations, and vehicle-structure interactions etc., are also presented. The target readers include industry professionals in civil, marine and mechanical engineering, as well as researchers and students in this area.

  17. Dynamic Calibration and Verification Device of Measurement System for Dynamic Characteristic Coefficients of Sliding Bearing

    Science.gov (United States)

    Chen, Runlin; Wei, Yangyang; Shi, Zhaoyang; Yuan, Xiaoyang

    2016-01-01

    The identification accuracy of dynamic characteristics coefficients is difficult to guarantee because of the errors of the measurement system itself. A novel dynamic calibration method of measurement system for dynamic characteristics coefficients is proposed in this paper to eliminate the errors of the measurement system itself. Compared with the calibration method of suspension quality, this novel calibration method is different because the verification device is a spring-mass system, which can simulate the dynamic characteristics of sliding bearing. The verification device is built, and the calibration experiment is implemented in a wide frequency range, in which the bearing stiffness is simulated by the disc springs. The experimental results show that the amplitude errors of this measurement system are small in the frequency range of 10 Hz–100 Hz, and the phase errors increase along with the increasing of frequency. It is preliminarily verified by the simulated experiment of dynamic characteristics coefficients identification in the frequency range of 10 Hz–30 Hz that the calibration data in this frequency range can support the dynamic characteristics test of sliding bearing in this frequency range well. The bearing experiments in greater frequency ranges need higher manufacturing and installation precision of calibration device. Besides, the processes of calibration experiments should be improved. PMID:27483283

  18. Nonlinear analysis of dynamic signature

    Science.gov (United States)

    Rashidi, S.; Fallah, A.; Towhidkhah, F.

    2013-12-01

    Signature is a long trained motor skill resulting in well combination of segments like strokes and loops. It is a physical manifestation of complex motor processes. The problem, generally stated, is that how relative simplicity in behavior emerges from considerable complexity of perception-action system that produces behavior within an infinitely variable biomechanical and environmental context. To solve this problem, we present evidences which indicate that motor control dynamic in signing process is a chaotic process. This chaotic dynamic may explain a richer array of time series behavior in motor skill of signature. Nonlinear analysis is a powerful approach and suitable tool which seeks for characterizing dynamical systems through concepts such as fractal dimension and Lyapunov exponent. As a result, they can be analyzed in both horizontal and vertical for time series of position and velocity. We observed from the results that noninteger values for the correlation dimension indicates low dimensional deterministic dynamics. This result could be confirmed by using surrogate data tests. We have also used time series to calculate the largest Lyapunov exponent and obtain a positive value. These results constitute significant evidence that signature data are outcome of chaos in a nonlinear dynamical system of motor control.

  19. Dynamic Analysis of a Pendulum Dynamic Automatic Balancer

    Directory of Open Access Journals (Sweden)

    Jin-Seung Sohn

    2007-01-01

    Full Text Available The automatic dynamic balancer is a device to reduce the vibration from unbalanced mass of rotors. Instead of considering prevailing ball automatic dynamic balancer, pendulum automatic dynamic balancer is analyzed. For the analysis of dynamic stability and behavior, the nonlinear equations of motion for a system are derived with respect to polar coordinates by the Lagrange's equations. The perturbation method is applied to investigate the dynamic behavior of the system around the equilibrium position. Based on the linearized equations, the dynamic stability of the system around the equilibrium positions is investigated by the eigenvalue analysis.

  20. Dynamic characteristics of heterogeneous media in vibrational and wave processes

    International Nuclear Information System (INIS)

    Fedotovskij, V.S.; Sinyavskij, V.F.; Terenik, L.V.; Spirov, V.S.; Kokorev, B.V.

    1986-01-01

    The complex mechanic systems involving a great quantity of the same type elements, in particular, the rod systems flowed around by the one- or two-phase flow are considered as the two- or three-phase heterogeneous media with certain effective properties. Some recommendations for calculating effective properties and determining those on a base of the dynamic characteristics of various heterogeneous systems are given. (author)

  1. Study on dynamic characteristics of reduced analytical model for PWR reactor internal structures

    International Nuclear Information System (INIS)

    Yoo, Bong; Lee, Jae Han; Kim, Jong Bum; Koo, Kyeong Hoe

    1993-01-01

    The objective of this study is to establish the procedure of the reduced analytical modeling technique for the PWR reactor internal(RI) structures and to carry out the sensitivity study of the dynamic characteristics of the structures by varying the structural parameters such as the stiffness, the mass and the damping. Modeling techniques for the PWR reactor internal structures and computer programs used for the dynamic analysis of the reactor internal structures are briefly investigated. Among the many components of RI structures, the dynamic characteristics for CSB was performed. The sensitivity analysis of the dynamic characteristics for the reduced analytical model considering the variations of the stiffnesses for the lower and upper flanges of the CSB and for the RV Snubber were performed to improve the dynamic characteristics of the RI structures against the external loadings given. In order to enhance the structural design margin of the RI components, the nonlinear time history analyses were attempted for the RI reduced models to compare the structural responses between the reference model and the modified one. (Author)

  2. The Influence of Industry Characteristics and Dynamic Capabilities on Firms’ Profitability

    Directory of Open Access Journals (Sweden)

    Maja Pervan

    2017-12-01

    Full Text Available The aim of this research was to explore one of the most intriguing dimensions of every firm’s business—its performance. Aside from analysing the influence of industry’s characteristics on the firm’s performance, the authors addressed the characteristics of dynamic capabilities and their role in contribution to the firm’s ultimate success. The analysis was conducted on a sample of 118 small Croatian manufacturing companies. The application of the Structural Equation Modelling (SEM approach revealed a statistically significant influence of both the industry’s characteristics (represented by Porter’s five forces framework and dynamic capabilities (based on Teece’s theory on the firm’s performance, where the influence of dynamic capabilities is proven to be larger than that of the industry.

  3. Substitution dynamical systems spectral analysis

    CERN Document Server

    Queffélec, Martine

    2010-01-01

    This volume mainly deals with the dynamics of finitely valued sequences, and more specifically, of sequences generated by substitutions and automata. Those sequences demonstrate fairly simple combinatorical and arithmetical properties and naturally appear in various domains. As the title suggests, the aim of the initial version of this book was the spectral study of the associated dynamical systems: the first chapters consisted in a detailed introduction to the mathematical notions involved, and the description of the spectral invariants followed in the closing chapters. This approach, combined with new material added to the new edition, results in a nearly self-contained book on the subject. New tools - which have also proven helpful in other contexts - had to be developed for this study. Moreover, its findings can be concretely applied, the method providing an algorithm to exhibit the spectral measures and the spectral multiplicity, as is demonstrated in several examples. Beyond this advanced analysis, many...

  4. Formal analysis of design process dynamics

    NARCIS (Netherlands)

    Bosse, T.; Jonker, C.M.; Treur, J.

    2010-01-01

    This paper presents a formal analysis of design process dynamics. Such a formal analysis is a prerequisite to come to a formal theory of design and for the development of automated support for the dynamics of design processes. The analysis was geared toward the identification of dynamic design

  5. Formal Analysis of Design Process Dynamics

    NARCIS (Netherlands)

    Bosse, T.; Jonker, C.M.; Treur, J.

    2010-01-01

    This paper presents a formal analysis of design process dynamics. Such a formal analysis is a prerequisite to come to a formal theory of design and for the development of automated support for the dynamics of design processes. The analysis was geared toward the identification of dynamic design

  6. Robustness Analysis of Dynamic Watermarks

    Directory of Open Access Journals (Sweden)

    Ivan V. Nechta

    2017-06-01

    Full Text Available In this paper we consider previously known scheme of dynamic watermarks embedding (Ra- dix-n that is used for preventing illegal use of software. According to the scheme a watermark is dynamic linked data structure (graph, which is created in memory during program execution. Hidden data, such as information about author, can be represented in a different type of graph structure. This data can be extracted and demonstrated in judicial proceedings. This paper declared that the above mentioned scheme was previously one of the most reliable, has a number of features that allows an attacker to detect a stage of watermark construction in the program, and therefore it can be corrupted or deleted. The author of this article shows the weakness of Radix-N scheme, which consists in the fact that we can reveal dynamic data structures of a program by using information received from some API-functions hooker which catches function calls of dynamic memory allocation. One of these data structures is the watermark. Pointers on dynamically created objects (arrays, variables, class items, etc. of a program can be detected by content analysis of computer's RAM. Different dynamic objects in memory interconnected by pointers form dynamic data structures of a program such as lists, stacks, trees and other graphs (including the watermark. Our experiment shows that in the vast majority of cases the amount of data structure in programs is small, which increases probability of a successful attack. Also we present an algorithm for finding connected components of a graph with linear time-consuming in cases where the number of nodes is about 106. On the basis of the experimental findings the new watermarking scheme has been presented, which is resistant to the proposed attack. It is offered to use different graph structure representation of a watermark, where edges are implemented using unique signatures. Our scheme uses content encrypting of graph nodes (except signature

  7. Spectral analysis of bedform dynamics

    DEFF Research Database (Denmark)

    Winter, Christian; Ernstsen, Verner Brandbyge; Noormets, Riko

    Successive multibeam echo sounder surveys in tidal channels off Esbjerg (Denmark) on the North Sea coast reveal the dynamics of subaquatic compound dunes. Mainly driven by tidal currents, dune structures show complex migration patterns in all temporal and spatial scales. Common methods for the an....... The proposed method overcomes the above mentioned problems of common descriptive analysis as it is an objective and straightforward mathematical process. The spectral decomposition of superimposed dunes allows a detailed description and analysis of dune patterns and migration.......Successive multibeam echo sounder surveys in tidal channels off Esbjerg (Denmark) on the North Sea coast reveal the dynamics of subaquatic compound dunes. Mainly driven by tidal currents, dune structures show complex migration patterns in all temporal and spatial scales. Common methods...... allows the application of a procedure, which has been a standard for the analysis of water waves for long times: The bathymetric signal of a cross-section of subaquatic compound dunes is approximated by the sum of a set of harmonic functions, derived by Fourier transformation. If the wavelength...

  8. Analysis of Vehicle Steering and Driving Bifurcation Characteristics

    Directory of Open Access Journals (Sweden)

    Xianbin Wang

    2015-01-01

    Full Text Available The typical method of vehicle steering bifurcation analysis is based on the nonlinear autonomous vehicle model deriving from the classic two degrees of freedom (2DOF linear vehicle model. This method usually neglects the driving effect on steering bifurcation characteristics. However, in the steering and driving combined conditions, the tyre under different driving conditions can provide different lateral force. The steering bifurcation mechanism without the driving effect is not able to fully reveal the vehicle steering and driving bifurcation characteristics. Aiming at the aforementioned problem, this paper analyzed the vehicle steering and driving bifurcation characteristics with the consideration of driving effect. Based on the 5DOF vehicle system dynamics model with the consideration of driving effect, the 7DOF autonomous system model was established. The vehicle steering and driving bifurcation dynamic characteristics were analyzed with different driving mode and driving torque. Taking the front-wheel-drive system as an example, the dynamic evolution process of steering and driving bifurcation was analyzed by phase space, system state variables, power spectral density, and Lyapunov index. The numerical recognition results of chaos were also provided. The research results show that the driving mode and driving torque have the obvious effect on steering and driving bifurcation characteristics.

  9. Determination of dynamic characteristics of multi-layer carbon plastic structures of high-resolution scanner

    Directory of Open Access Journals (Sweden)

    В. Н. Маслей

    2017-10-01

    Full Text Available The comparative analysis results for the numerical determination of the dynamic characteristics of multi-layer carbon-fiber plates of the space vehicle scanner design by various types of finite element approximation of the physico-mechanical properties of the composite material are presented. Using the topological structure of the construction of reinforcing layers material in the plate package plane, experimental data for the elastic and mass characteristics of homogeneous carbon-fiber fibers, equivalent structural and orthotropic stiffness and elastic characteristics of the material of composite plates are determined.

  10. DYNAMICS OF VIBRATION FEEDERS WITH A NONLINEAR ELASTIC CHARACTERISTIC

    Directory of Open Access Journals (Sweden)

    V. I. Dyrda

    2017-04-01

    Full Text Available Purpose. Subject to the smooth and efficient operation of each production line, is the use of vehicles transporting high specification. It worked well in practice for transporting construction machines, which are used during the vibration. The use of vibration machines requires optimization of their operation modes. In the form of elastic link in them are increasingly using rubber-metallic elements, which are characterized by nonlinear damping properties. So it is necessary to search for new, more modern, methods of calculation of dynamic characteristics of the vibration machines on the properties of rubber as a cushioning material. Methodology. The dynamics of vibration machine that is as elastic rubber block units and buffer shock absorbers limiting the amplitude of the vibrations of the working body. The method of determining amplitude-frequency characteristics of the vibrating feeder is based on the principle of Voltaire, who in the calculations of the damping properties of the dampers will allow for elastic-hereditary properties of rubber. When adjusting the basic dynamic stiffness of the elastic ties and vibratory buffers, using the principle of heredity rubber properties, determine the dependence of the amplitude of the working body of the machine vibrations. This method is called integro-operator using the fractional-exponential kernels of relaxation. Findings. Using the derived formula for determining the amplitude of the resonance curve is constructed one-mass nonlinear system. It is established that the use of the proposed method of calculation will provide a sufficiently complete description of the damping parameters of rubber-metallic elements and at the same time be an effective means of calculating the amplitude-frequency characteristics of nonlinear vibration systems. Originality. The authors improved method of determining damping characteristics of rubber-metallic elements and the amplitude-frequency characteristics of nonlinear

  11. Structural dynamic analysis of turbine blade

    Science.gov (United States)

    Antony, A. Daniel; Gopalsamy, M.; Viswanadh, Chaparala B. V.; Krishnaraj, R.

    2017-10-01

    In any gas turbine design cycle, blade design is a crucial element which needs maximum attention to meet the aerodynamic performance, structural safety margins, manufacturing feasibility, material availability etc. In present day gas turbine engines, most of the failures occur during engine development test and in-service, in rotor and stator blades due to fatigue and resonance failures. To address this issue, an extensive structural dynamic analysis is carried out to predict the natural frequencies and mode shapes using FE methods. Using the dynamics characteristics, the Campbell diagram is constructed to study the possibility of resonance at various operating speeds. In this work, the feasibility of using composite material in place of titanium alloy from the structural dynamics point of view. This is being attempted in a Low-pressure compressor where the temperatures are relatively low and fixed with the casings. The analysis will be carried out using FE method for different composite material with different lamina orientations chosen through the survey. This study will focus on the sensitivity of blade mode shapes to different laminae orientations, which will be used to alter the natural frequency and tailor the mode shapes. Campbell diagrams of existing titanium alloy are compared with the composite materials with different laminae at all critical operating conditions. The existing manufacturing methods and the proven techniques for blade profiles will also be discussed in this report.

  12. Vehicle Unsteady Dynamics Characteristics Based on Tire and Road Features

    Directory of Open Access Journals (Sweden)

    Bin Ma

    2013-01-01

    Full Text Available During automotive related accidents, tire and road play an important role in vehicle unsteady dynamics as they have a significant impact on the sliding friction. The calculation of the rubber viscoelastic energy loss modulus and the true contact area model is improved based on the true contact area and the rubber viscoelastic theory. A 10 DOF full vehicle dynamic model in consideration of the kinetic sliding friction coefficient which has good accuracy and reality is developed. The stability test is carried out to evaluate the effectiveness of the model, and the simulation test is done in MATLAB to analyze the impact of tire feature and road self-affine characteristics on the sport utility vehicle (SUV unsteady dynamics under different weights. The findings show that it is a great significance to analyze the SUV dynamics equipped with different tire on different roads, which may provide useful insights into solving the explicit-implicit features of tire prints in systematically and designing active safety systems.

  13. ABOUT SOME DYNAMIC CHARACTERISTICS OF INDIVIDUAL METEOREACTIONS: GENERAL ASPECTS

    Directory of Open Access Journals (Sweden)

    E. G. Zhuravishkina

    2015-01-01

    Full Text Available The interaction of organism and environment is essential for human existence, and in the natural impact the main are solar-terrestrial relations. Influence of solar activity is carried out directly through the electro-magnetic field, and indirectly, through the effects of meteorological factors. All people are meteo-sensitive. The degree of sensitivity depends of health, age and type of the estimated impact factor, and environmental features of human location. The basic laws of individual meteo-helio-reactions of human psychophysiological indicators at an early and mature age stages are determined. These researches were carried out with a single cycle of observation, but the same patterns and features of meteo-helio-influence with repeated observation are poorly understood. Article is devoted to dynamic characteristics of individual meteo-reactions of healthy people and patients with cardiovascular disease in adulthood. The study involved shift workers Siberia. Studied the effect of changes in air temperature and atmospheric pressure on the dynamics of blood pressure and heart rate in a two cycles of observation, the dynamics of adaptation levels in cycles is examined. The study revealed the existence of both conserved and different parameters for dynamic monitoring of human meteo-reactions. That allows to put forward a hypothesis that meteo-adaptation it is not a reaction to the current external impact, but the result of the realization of adaptation program, already existing in the body, in specific conditions.

  14. Evaluation of Dynamic Characteristics of the Footbridge with Integral Abutments

    Directory of Open Access Journals (Sweden)

    Pańtak Marek

    2017-09-01

    Full Text Available The paper presents the results of dynamic field tests and numerical analysis of the footbridge designed as a three-span composite structure with integral abutments. The adopted design solution which has allowed to achieve a high resistance of the structure to dynamic loads and to meet the requirements of the criteria of comfort of use with a large reserve has been characterized. For comparative purposes, numerical analyzes of three construction variants of the footbridge were presented: F-1 - construction with integral abutments (realized variant, F-2 - construction with girders anchored in the abutments by means of tension rocker bearings, F-3 - construction with concrete side spans.

  15. Evaluation of Dynamic Characteristics of the Footbridge with Integral Abutments

    Science.gov (United States)

    Pańtak, Marek; Jarek, Bogusław

    2017-09-01

    The paper presents the results of dynamic field tests and numerical analysis of the footbridge designed as a three-span composite structure with integral abutments. The adopted design solution which has allowed to achieve a high resistance of the structure to dynamic loads and to meet the requirements of the criteria of comfort of use with a large reserve has been characterized. For comparative purposes, numerical analyzes of three construction variants of the footbridge were presented: F-1 - construction with integral abutments (realized variant), F-2 - construction with girders anchored in the abutments by means of tension rocker bearings, F-3 - construction with concrete side spans.

  16. Human dynamics scaling characteristics for aerial inbound logistics operation

    Science.gov (United States)

    Wang, Qing; Guo, Jin-Li

    2010-05-01

    In recent years, the study of power-law scaling characteristics of real-life networks has attracted much interest from scholars; it deviates from the Poisson process. In this paper, we take the whole process of aerial inbound operation in a logistics company as the empirical object. The main aim of this work is to study the statistical scaling characteristics of the task-restricted work patterns. We found that the statistical variables have the scaling characteristics of unimodal distribution with a power-law tail in five statistical distributions - that is to say, there obviously exists a peak in each distribution, the shape of the left part closes to a Poisson distribution, and the right part has a heavy-tailed scaling statistics. Furthermore, to our surprise, there is only one distribution where the right parts can be approximated by the power-law form with exponent α=1.50. Others are bigger than 1.50 (three of four are about 2.50, one of four is about 3.00). We then obtain two inferences based on these empirical results: first, the human behaviors probably both close to the Poisson statistics and power-law distributions on certain levels, and the human-computer interaction behaviors may be the most common in the logistics operational areas, even in the whole task-restricted work pattern areas. Second, the hypothesis in Vázquez et al. (2006) [A. Vázquez, J. G. Oliveira, Z. Dezsö, K.-I. Goh, I. Kondor, A.-L. Barabási. Modeling burst and heavy tails in human dynamics, Phys. Rev. E 73 (2006) 036127] is probably not sufficient; it claimed that human dynamics can be classified as two discrete university classes. There may be a new human dynamics mechanism that is different from the classical Barabási models.

  17. Characteristics and modeling of spruce wood under dynamic compression load

    International Nuclear Information System (INIS)

    Eisenacher, Germar

    2014-01-01

    Spruce wood is frequently used as an energy absorbing material in impact limiters of packages for the transportation of radioactive material. A 9m drop test onto an unyielding target is mandatory for the packages. The impact results in a dynamic compression load of the spruce wood inside the impact limiter. The lateral dilation of the wood is restrained thereby due to encasing steel sheets. This work's objective was to provide a material model for spruce wood based on experimental investigations to enable the calculation of such loading conditions. About 600 crush tests with cubical spruce wood specimens were performed to characterize the material. The compression was up to 70% and the material was assumed to be transversely isotropic. Particularly the lateral constraint showed to have an important effect: the material develops a high lateral dilation without lateral constraint. The force-displacement characteristics show a comparably low force level and no or only slight hardening. Distinctive softening occurs after the linear-elastic region when loaded parallel to the fiber. On the other hand, using a lateral constraint results in significantly higher general force levels, distinctive hardening and lateral forces. The softening effect when loaded parallel to the fiber is less distinctive. Strain rate and temperature raise or lower the strength level, which was quantified for the applicable ranges of impact limiters. The hypothesis of an uncoupled evolution of the yield surface was proposed based on the experimental findings. It postulates an independent strength evolution with deviatoric and volumetric deformation. The hypothesis could be established using the first modeling approach, the modified LS-DYNA material model MAT075. A transversely isotropic material model was developed based thereupon and implemented in LS-DYNA. The material characteristics of spruce wood were considered using a multi-surface yield criterion and a non-associated flow rule. The yield

  18. Study on Dynamic Characteristics of Microbial Enhanced Oil Recovery

    Science.gov (United States)

    Zhao, Yang; Shi, Fang; Qin, Wuying; Yan, Jing

    2018-01-01

    With the rapid development of economy, the demand for oil is increasing day by day. MEOR has the advantages of low cost and no pollution to the environment, attracted widespread attention. In this paper, the dynamic characteristics of microbial enhanced oil recovery were studied by laboratory experiments. The result showed that all the microbial flooding recovery rate could reach more than 5%, and the total recovery could reach more than 35% and if the injection period of microbial composite system was advanced, the whole oil displacement process could be shortened and the workload would be reduced.

  19. Model of Coupled Drives Apparatus – Static and Dynamic Characteristics

    Directory of Open Access Journals (Sweden)

    Chalupa Petr

    2016-01-01

    Full Text Available The paper presents an initial part of a modelling the Coupled Drives Apparatus CE108 developed by TecQuipment Ltd. The final model should be used in the process of control design for the apparatus. The model derived by the developers of the apparatus using first-principle modelling is used as a starting point for comparison of its properties with measured characteristics. The static and dynamic characteristics of the real-time apparatus are presented and discussed. Special attention is paid to principal differences between the model and the real-time apparatus. Real-time measurements are obtained using MATLAB / Simulink environment in connection with a Real-time Toolbox. Evaluation of the experiments is also performed in the MATLAB environment

  20. On the characteristics of a numerical fluid dynamics simulator

    International Nuclear Information System (INIS)

    Winkler, K.H.A.; Norman, M.L.; Norton, J.L.

    1986-01-01

    John von Neumann envisioned scientists and mathematicians analyzing and controlling their numerical experiments on nonlinear dynamic systems interactively. The authors describe their concept of a real-time Numerical Fluid Dynamics Simulator NFDS. The authors envision the NFDS to be composed of simulation processors, data storage devices, and image processing devices of extremely high power and capacity, interconnected by very high throughput communication channels. They present individual component performance requirements for both real-time and playback operating modes of the NFDS, using problems of current interest in fluid dynamics as examples. Scaling relations are derived showing the dependence of system requirements on the dimensionality and complexity of the numerical model. The authors conclude by extending their analysis to the system requirements posed in modeling the more involved physics of radiation hydrodynamics

  1. Relationships between Isometric Force-Time Characteristics and Dynamic Performance

    Directory of Open Access Journals (Sweden)

    Thomas Dos’Santos

    2017-09-01

    Full Text Available The purpose of this study was to explore the relationships between isometric mid-thigh pull (IMTP force-time characteristics (peak force and time-specific force vales (100–250 ms and dynamic performance and compare dynamic performance between stronger and weaker athletes. Forty-three athletes from different sports (rowing, soccer, bicycle motocross, and hockey performed three trials of the squat jump (SJ, countermovement jump (CMJ, and IMTP, and performed a one repetition maximum power clean (PC. Reactive strength index modified (RSImod was also calculated from the CMJ. Statistically significant large correlations between IMTP force-time characteristics and PC (ρ = 0.569–0.674, p < 0.001, and moderate correlations between IMTP force-time characteristics (excluding force at 100 ms and RSImod (ρ = 0.389–0.449, p = 0.013–0.050 were observed. Only force at 250 ms demonstrated a statistically significant moderate correlation with CMJ height (ρ = 0.346, p = 0.016 and no statistically significant associations were observed between IMTP force-time characteristics and SJ height. Stronger athletes (top 10 demonstrated statistically significantly greater CMJ heights, RSImods, and PCs (p ≤ 0.004, g = 1.32–1.89 compared to weaker (bottom 10 athletes, but no differences in SJ height were observed (p = 0.871, g = 0.06. These findings highlight that the ability to apply rapidly high levels of force in short time intervals is integral for PC, CMJ height, and reactive strength.

  2. Dynamic Stall Characteristics of Drooped Leading Edge Airfoils

    Science.gov (United States)

    Sankar, Lakshmi N.; Sahin, Mehmet; Gopal, Naveen

    2000-01-01

    Helicopters in high-speed forward flight usually experience large regions of dynamic stall over the retreating side of the rotor disk. The rapid variations in the lift and pitching moments associated with the stall process can result in vibratory loads, and can cause fatigue and failure of pitch links. In some instances, the large time lag between the aerodynamic forces and the blade motion can trigger stall flutter. A number of techniques for the alleviation of dynamic stall have been proposed and studied by researchers. Passive and active control techniques have both been explored. Passive techniques include the use of high solidity rotors that reduce the lift coefficients of individual blades, leading edge slots and leading edge slats. Active control techniques include steady and unsteady blowing, and dynamically deformable leading edge (DDLE) airfoils. Considerable amount of experimental and numerical data has been collected on the effectiveness of these concepts. One concept that has not received as much attention is the drooped-leading edge airfoil idea. It has been observed in wind tunnel studies and flight tests that drooped leading edge airfoils can have a milder dynamic stall, with a significantly milder load hysteresis. Drooped leading edge airfoils may not, however, be suitable at other conditions, e.g. in hover, or in transonic flow. Work needs to be done on the analysis and design of drooped leading edge airfoils for efficient operation in a variety of flight regimes (hover, dynamic stall, and transonic flow). One concept that is worthy of investigation is the dynamically drooping airfoil, where the leading edge shape is changed roughly once-per-rev to mitigate the dynamic stall.

  3. Dynamic characteristics and mechatronics model for maglev blood pump

    Science.gov (United States)

    Sun, Kun; Chen, Chen

    2017-01-01

    Magnetic bearing system(MBs) has been developed in the new-generation blood pump due to its low power consumption, low blood trauma and high durability. However, MBs for a blood pump were almost influenced by a series of factors such as hemodynamics, rotation speeds and actuator response in working fluids, compared with those applied in other industrial fields. In this study, the dynamic characteristics of MBs in fluid environments, including the influence of the pumping fluid and rotation of the impeller on the radial dynamic model were investigated by measuring the frequency response to sinusoidal excitation upon coils, and the response of radial displacement during a raise in the speed. The excitation tests were conducted under conditions in which the blood pump was levitated in air and water and with or without rotation. The experimental and simulated results indicate that rotations of the impeller affected the characteristics of MBs in water apparently, and the vibration in water was decreased, compared with that in air due to the hydraulic force. During the start-up and rotation, the actuator failed to operate fully and timely, and the voltage supplied can be chosen under the consideration of the rotor displacement and consumption.

  4. The Dynamic Characteristic and Hysteresis Effect of an Air Spring

    Science.gov (United States)

    Löcken, F.; Welsch, M.

    2015-02-01

    In many applications of vibration technology, especially in chassis, air springs present a common alternative to steel spring concepts. A design-independent and therefore universal approach is presented to describe the dynamic characteristic of such springs. Differential and constitutive equations based on energy balances of the enclosed volume and the mountings are given to describe the nonlinear and dynamic characteristics. Therefore all parameters can be estimated directly from physical and geometrical properties, without parameter fitting. The numerically solved equations fit very well to measurements of a passenger car air spring. In a second step a simplification of this model leads to a pure mechanical equation. While in principle the same parameters are used, just an empirical correction of the effective heat transfer coefficient is needed to handle some simplification on this topic. Finally, a linearization of this equation leads to an analogous mechanical model that can be assembled from two common spring- and one dashpot elements in a specific arrangement. This transfer into "mechanical language" enables a system description with a simple force-displacement law and a consideration of the nonobvious hysteresis and stiffness increase of an air spring from a mechanical point of view.

  5. Nike Black Brant V high altitude dynamic instability characteristics

    Science.gov (United States)

    Montag, W. H.; Walker, L. L., Jr.

    1979-01-01

    Flight experience on the Nike Black Brant V has demonstrated the existence of plume induced flow separation over the fins and aft body of the Black Brant V motor. Modelling of the forces associated with this phenomenon as well as analysis of the resultant vehicle coning motion and its effect on the velocity vector heading are presented. A summary of Nike Black Brant V flight experience with high altitude dynamic instability is included.

  6. Dynamic Heterogeneous Multiscale Filtration Model: Probing Micro- and Macroscopic Filtration Characteristics of Gasoline Particulate Filters.

    Science.gov (United States)

    Gong, Jian; Viswanathan, Sandeep; Rothamer, David A; Foster, David E; Rutland, Christopher J

    2017-10-03

    Motivated by high filtration efficiency (mass- and number-based) and low pressure drop requirements for gasoline particulate filters (GPFs), a previously developed heterogeneous multiscale filtration (HMF) model is extended to simulate dynamic filtration characteristics of GPFs. This dynamic HMF model is based on a probability density function (PDF) description of the pore size distribution and classical filtration theory. The microstructure of the porous substrate in a GPF is resolved and included in the model. Fundamental particulate filtration experiments were conducted using an exhaust filtration analysis (EFA) system for model validation. The particulate in the filtration experiments was sampled from a spark-ignition direct-injection (SIDI) gasoline engine. With the dynamic HMF model, evolution of the microscopic characteristics of the substrate (pore size distribution, porosity, permeability, and deposited particulate inside the porous substrate) during filtration can be probed. Also, predicted macroscopic filtration characteristics including particle number concentration and normalized pressure drop show good agreement with the experimental data. The resulting dynamic HMF model can be used to study the dynamic particulate filtration process in GPFs with distinct microstructures, serving as a powerful tool for GPF design and optimization.

  7. Characteristics of dynamic triaxial testing of asphalt mixtures

    Science.gov (United States)

    Ulloa Calderon, Alvaro

    Due to the increasing traffic loads and tire pressures, a serious detrimental impact has occurred on flexible pavements in the form of excessive permanent deformation once the critical combination of loading and environmental conditions are reached. This distress, also known as rutting, leads to an increase in road roughness and ultimately jeopardizes the road users' safety. The flow number (FN) simple performance test for asphalt mixtures was one of the final three tests selected for further evaluation from the twenty-four test/material properties initially examined under the NCHRP 9-19 project. Currently, no standard triaxial testing conditions in terms of the magnitude of the deviator and confining stresses have been specified. In addition, a repeated haversine axial compressive load pulse of 0.1 second and a rest period of 0.9 second are commonly used as part of the triaxial testing conditions. The overall objective of this research was to define the loading conditions that created by a moving truck load in the hot mixed asphalt (HMA) layer. The loading conditions were defined in terms of the triaxial stress levels and the corresponding loading time. Dynamic mechanistic analysis with circular stress distribution was used to closely simulate field loading conditions. Extensive mechanistic analyses of three different asphalt pavement structures subjected to moving traffic loads at various speeds and under braking and non-braking conditions were conducted using the 3D-Move model. Prediction equations for estimating the anticipated deviator and confining stresses along with the equivalent deviator stress pulse duration as a function of pavement temperature, vehicle speed, and asphalt mixture's stiffness have been developed. The magnitude of deviator stress, sigmad and confining stress, sigmac, were determined by converting the stress tensor computed in the HMA layer at 2" below pavement surface under a moving 18-wheel truck using the octahedral normal and shear

  8. Modal analysis application for dynamic characterization of simple structures

    International Nuclear Information System (INIS)

    Pastorini, A.J.; Belinco, C.G.

    1987-01-01

    The knowledge of the dynamic characteristics of a structure helps to foresee the vibrating behaviour under operating conditions. The modal analysis techniques offer a method to perform the dynamic characterization of a studied structure from the vibration modes of such structure. A hammer provided with a loaded cell to excite a wide frequency band and accelerometer and, on the basis of a measurement of the transfer function at different points, various simple structures were given with a dynamic structures analysis (of the type of Fourier's rapidly transformation) and the results were compared with those obtained by other methods. Different fields where these techniques are applied, are also enumerated. (Author)

  9. Vehicle systems: coupled and interactive dynamics analysis

    Science.gov (United States)

    Vantsevich, Vladimir V.

    2014-11-01

    This article formulates a new direction in vehicle dynamics, described as coupled and interactive vehicle system dynamics. Formalised procedures and analysis of case studies are presented. An analytical consideration, which explains the physics of coupled system dynamics and its consequences for dynamics of a vehicle, is given for several sets of systems including: (i) driveline and suspension of a 6×6 truck, (ii) a brake mechanism and a limited slip differential of a drive axle and (iii) a 4×4 vehicle steering system and driveline system. The article introduces a formal procedure to turn coupled system dynamics into interactive dynamics of systems. A new research direction in interactive dynamics of an active steering and a hybrid-electric power transmitting unit is presented and analysed to control power distribution between the drive axles of a 4×4 vehicle. A control strategy integrates energy efficiency and lateral dynamics by decoupling dynamics of the two systems thus forming their interactive dynamics.

  10. Dynamical analysis of highly excited molecular spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kellman, M.E. [Univ. of Oregon, Eugene (United States)

    1993-12-01

    The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

  11. Transient Dynamics Analysis of The Reachstacker Speader Based On ANSYS

    Directory of Open Access Journals (Sweden)

    Shu Yu Feng

    2016-01-01

    Full Text Available Reachstacker is an indispensable handling machinery, it will inevitably lead to unbalanced force at the job site. This paper does transient dynamics analysis for the spreader mechanism, which is one of the most significance key components. We get dynamic response of the spreader in lifting instant, results not only provide a reference for designers to understand the mechanical characteristics of spreader comprehensively, but also bedding for the future research.

  12. Fluid mechanics of dynamic stall. II - Prediction of full scale characteristics

    Science.gov (United States)

    Ericsson, L. E.; Reding, J. P.

    1988-01-01

    Analytical extrapolations are made from experimental subscale dynamics to predict full scale characteristics of dynamic stall. The method proceeds by establishing analytic relationships between dynamic and static aerodynamic characteristics induced by viscous flow effects. The method is then validated by predicting dynamic test results on the basis of corresponding static test data obtained at the same subscale flow conditions, and the effect of Reynolds number on the static aerodynamic characteristics are determined from subscale to full scale flow conditions.

  13. Dynamic characteristics of stay cables with inerter dampers

    Science.gov (United States)

    Shi, Xiang; Zhu, Songye

    2018-06-01

    This study systematically investigates the dynamic characteristics of a stay cable with an inerter damper installed close to one end of a cable. The interest in applying inerter dampers to stay cables is partially inspired by the superior damping performance of negative stiffness dampers in the same application. A comprehensive parametric study on two major parameters, namely, inertance and damping coefficients, are conducted using analytical and numerical approaches. An inerter damper can be optimized for one vibration mode of a stay cable by generating identical wave numbers in two adjacent modes. An optimal design approach is proposed for inerter dampers installed on stay cables. The corresponding optimal inertance and damping coefficients are summarized for different damper locations and interested modes. Inerter dampers can offer better damping performance than conventional viscous dampers for the target mode of a stay cable that requires optimization. However, additional damping ratios in other vibration modes through inerter damper are relatively limited.

  14. Study of Dynamic Characteristics of Slow-Changing Process

    Directory of Open Access Journals (Sweden)

    Yinong Li

    2000-01-01

    Full Text Available A vibration system with slow-changing parameters is a typical nonlinear system. Such systems often occur in the working and controlled process of some intelligent structures when vibration and deformation exist synchronously. In this paper, a system with slow-changing stiffness, damping and mass is analyzed in an intelligent structure. The relationship between the amplitude and the frequency of the system is studied, and its dynamic characteristic is also discussed. Finally, a piecewise linear method is developed on the basis of the asymptotic method. The simulation and the experiment show that a suitable slow-changing stiffness can restrain the amplitude of the system when the system passes through the resonant region.

  15. Vibration characteristics analysis for HANARO fuel assembly

    International Nuclear Information System (INIS)

    Ryu, Jeong Soo; Yoon, Doo Byung

    2001-06-01

    For investigating the vibration characteristics of HANARO fuel assembly, the finite element models of the in-air fuel assemblies and flow tubes were developed. By calculating the hydrodynamic mass and distributing it on the in-air models, the in-water models of the flow tubes and the fuel assemblies were developed. Then, modal analysis of the developed models was carried out. The analysis results show that the fundamental vibration modes of the in-air 18-element and 36-element fuel assemblies are lateral bending modes and its corresponding natural frequencies are 26.4Hz and 27.7Hz, respectively. The fundamental natural frequency of the in-water 18-element and 36-element fuel assemblies were obtained as 16.1Hz and 16.5Hz. For the verification of the developed finite element models, modal analysis results were compared with those obtained from the modal test. These results demonstrate that the natural frequencies of lower order modes obtained from finite element analysis agree well with those of the modal test and the estimation of the hydrodynamic mass is appropriate. It is expected that the analysis results will be applied as a basic data for the operation and management of the HANARO. In addition, when it is necessary to improve the design of the fuel assembly, the developed finite element models will be utilized as a base model for the vibration characteristic analysis of the modified fuel assembly

  16. Dynamic drawing characteristics of preschool and younger school age children

    Directory of Open Access Journals (Sweden)

    Cvetković Andrijana

    2014-01-01

    Full Text Available The main objective of this research is to determine developmental characteristics of dynamic drawings of preschool and younger school age children. The sample consists of 90 typical developed children, aged between 6 and 9. The sample includes 47 (52.2% girls and 43 (47.8% boys from preschool institutions and elementary schools in Pirot and Belgrade. Action representation in dynamic drawings was evaluated using three types of drawings: a man who runs, a man shooting a ball and a man lifting a ball from the floor. We determined that a very small number of the respondents reaches the highest level of graphical representation of figures in motion, and that girl’s achievements are better than boy’s achievements. However, this result is on the border of statistical significance (p=0.052. Also, there is a statistically significant trend of progress to higher levels of action representation (p=0.000 with the increase in chronological age of the respondents.

  17. Dynamic Characteristics of Electrostatically Actuated Microbeams with Slant Crack

    Directory of Open Access Journals (Sweden)

    Han Zhou

    2015-01-01

    Full Text Available An improved model of the slant crack on a microbeam is presented. Based on fracture mechanics, the rotation coefficient for the slant crack is derived as a massless rotational spring accounting for the additional stress intensity factors generated by the orientation of the crack compared to the transverse crack. Comparisons between microbeams with a slant crack of different geometry parameters (slant angle, depth ratio, and crack position are investigated with regard to the dynamic mechanical behaviors and nonlinear response. By presenting a mathematical modeling, the effects of the slant crack and the electric actuation of an electrostatically actuated fixed-fixed microbeam on the dynamic characteristics are examined in detail. It is shown that the crack position has more significant influence on the pull-in voltage value than the slant angle or the depth ratio. Approaching the slant crack to the fixed end or enlarging the external incentives amplifies the nonlinearity of the microbeam system, while the effects of depth ratio and slant angle are dependent on the crack position. The resonance frequency and the resonance amplitude are affected as well.

  18. [Monochromatic aberration in accommodation. Dynamic wavefront analysis].

    Science.gov (United States)

    Fritzsch, M; Dawczynski, J; Jurkutat, S; Vollandt, R; Strobel, J

    2011-06-01

    Monochromatic aberrations may influence the visual acuity of the eye. They are not stable and can be affected by different factors. The subject of the following paper is the dynamic investigation of the changes in wavefront aberration with accommodation. Dynamic measurement of higher and lower order aberrations was performed with a WASCA Wavefront Analyzer (Carl-Zeiss-Meditec) and a specially constructed target device for aligning objects in far and near distances on 25 subjects aged from 15 to 27 years old. Wavefront aberrations showed some significant changes in accommodation. In addition to the characteristic sphere reaction accompanying miosis and changes in horizontal prism (Z(1) (1)) in the sense of a convergence movement of the eyeball also occurred. Furthermore defocus rose (Z(2) (0)) and astigmatism (Z(2) (-2)) changed. In higher-order aberrations a decrease in coma-like Zernike polynomials (Z(3) (-1), Z(3) (1)) was found. The most obvious change appeared in spherical aberration (Z(4) (0)) which increased and changed from positive to negative. In addition the secondary astigmatism (Z(4) (-2)) and quadrafoil (Z(4) (4)) rise also increased. The total root mean square (RMS), as well as the higher-order aberrations (RMS-HO) significantly increased in accommodation which is associated with a theoretical reduction of visual acuity. An analysis of the influence of pupil size on aberrations showed significant increases in defocus, spherical aberration, quadrafoil, RMS and RMS HO by increasing pupil diameter. By accommodation-associated miosis, the growing aberrations are partially compensated by focusing on near objects. Temporal analysis of the accommodation process with dynamic wavefront analysis revealed significant delays in pupil response and changing of prism in relation to the sphere reaction. In accommodation to near objects a discrete time ahead of third order aberrations in relation to the sphere response was found. Using dynamic wavefront measurement

  19. Noninvasive Monitoring of Soil Static Characteristics and Dynamic States

    DEFF Research Database (Denmark)

    Cassiani, Giorgio; Ursino, Nadia; Deiana, Rita

    2012-01-01

    of possible climatic changes. We used long-term electromagnetic induction (EMI) time lapse monitoring and short-term irrigation experiments monitored using electrical resistivity tomography (ERT) and EMI, supported by time domain reflectometry (TDR) soil moisture measurements. Mapping of natural ?-ray...... emission, texture analysis, and laboratory calibration of an electrical constitutive relationship on soil samples complete the dataset. We observe that the growth of vegetation, with the associated below-ground allocation of biomass, has a significant impact on the soil moisture dynamics. It is well known...

  20. Dynamic characteristics of a perforated cylindrical shell for flow distribution in SMART

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seungho; Choi, Youngin; Ha, Kyungrok [Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Park, Kyoung-Su, E-mail: pks6348@yonsei.ac.kr [Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Park, No-Cheol; Park, Young-Pil [Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Jeong, Kyeong-Hoon; Park, Jin-Seok [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong, Daejeon 305-303 (Korea, Republic of)

    2011-10-15

    Highlights: > A 1/12 scaled-down flow skirt is manufactured and a modal test is performed. > A finite element model predicts the added mass effect of the perforated cylindrical shell. > Modal characteristics are extracted by considering the fluid-structure interaction. - Abstract: The System-integrated Modular Advanced ReacTor (SMART) is a small nuclear reactor under development in Korea. It is equipped with a perforated cylindrical shell, which is called a flow skirt, in the lower plenum of the reactor for uniform flow distribution and to prevent inflow of debris into the core. This perforated cylindrical shell can be excited by external forces such as seismic or pump pulsation loads. The dynamic characteristics of the perforated cylindrical shell must be identified for further dynamic analysis. This research explores the modal analysis of the scaled-down flow skirt model submerged in coolant water. For the numerical simulation, finite element analysis is carried out to extract modal characteristics of the structure considering the fluid-structure interaction and we introduce the NAVMI factor for similarity analysis. In the finite element model, the whole shape of the perforated cylindrical shell is simulated instead of using the effective material properties. In addition, a 1/12 scaled-down flow skirt is manufactured, and an experiment is designed using an exciter and waterproof accelerometers for the modal test. Due to excellent agreement between the modal test results and the finite element analysis results such as natural frequencies and mode shapes, the finite element model is validated and can be used to predict the dynamic characteristics of the real flow skirt. Moreover, the natural frequency of the real flow skirt can be calculated from the NAVMI factor and is in good agreement with the FEM result.

  1. Dynamic analysis of embedded structures

    International Nuclear Information System (INIS)

    Kausel, E.; Whitman, R.V.; Morray, J.P.

    1977-01-01

    The paper presents simplified rules to account for embeddment and soil layering in the soil-structure interaction problem, to be used in dynamic analysis. The relationship between the spring method, and a direct solution (in which both soil and structure are modeled with finite elements and linear members) is first presented. It is shown that for consistency of the results with the two solution methods the spring method should be performed in the following three steps: 1. Determination of the motion of the massless foundation (having the same shape as the actual one) when subjected to the same input motion as the direct solution. 2. Determination of the frequency dependent subgrade stiffness for the relevant degrees of freedom. 3. Computations of the response of the real structure supported on frequency dependent soil springs and subjected at the base of these springs to the motion computed in step 1. The first two steps require, in general, finite element methods, which would make the procedure not attractive. It is shown in the paper, however, that excellent approximations can be obtained, on the basis of 1-dimensional wave propagation theory for the solution of step 1, and correction factors modifying for embeddment the corresponding springs of a surface footing on a layered stratum, for the solution of step 2. (Auth.)

  2. Systems-Dynamic Analysis for Neighborhood Study

    Science.gov (United States)

    Systems-dynamic analysis (or system dynamics (SD)) helps planners identify interrelated impacts of transportation and land-use policies on neighborhood-scale economic outcomes for households and businesses, among other applications. This form of analysis can show benefits and tr...

  3. Defining Dynamic Characteristics of Multilink Pendulum System with Comparison of the Calculated and Experimental Results

    Directory of Open Access Journals (Sweden)

    V. A. Gribkov

    2015-01-01

    Full Text Available We consider the multilink pendulum system consisting of six physical pendulums. A pendulum (carrier has inertia parameters, which significantly exceed the remaining (carried ones placed on the carrier. In addition to the system under analysis, in particular, the paper presents a design scheme for a two-stage liquid fuel rocket using pendulums as the analogues of fluctuating fuel. Pendulum models also find application to solve problems of stabilization of space tether systems. The objective of the study is to determine dynamic characteristics of the said sixmembered pendulum system, as well as to identify specific dynamic properties inherent in objects of this kind. Dynamic characteristics of the system are determined by calculations. A physical model of the pendulum allowed us to compare the calculated and experimental results. To conduct the frequency tests of the pendulum model three pilot units have been created. The first two units turned out to be inappropriate for fulfilling the experimental tasks for various reasons. The third unit enabled us to obtain desirable experimental results. The "calculation–experiment” discrepancy on the natural frequencies of the pendulum model for the majority of frequencies was less than 5%. We analyzed the dynamic features of multilink pendulum systems "carried by the carrier unit links". The analysis results are applicable to the above-noted object classes of rocket and space technology.

  4. Dynamical Analysis of the Global Warming

    Directory of Open Access Journals (Sweden)

    J. A. Tenreiro Machado

    2012-01-01

    Full Text Available Global warming is a major concern nowadays. Weather conditions are changing, and it seems that human activity is one of the main causes. In fact, since the beginning of the industrial revolution, the burning of fossil fuels has increased the nonnatural emissions of carbon dioxide to the atmosphere. Carbon dioxide is a greenhouse gas that absorbs the infrared radiation produced by the reflection of the sunlight on the Earth’s surface, trapping the heat in the atmosphere. Global warming and the associated climate changes are being the subject of intensive research due to their major impact on social, economic, and health aspects of human life. This paper studies the global warming trend in the perspective of dynamical systems and fractional calculus, which is a new standpoint in this context. Worldwide distributed meteorological stations and temperature records for the last 100 years are analysed. It is shown that the application of Fourier transforms and power law trend lines leads to an assertive representation of the global warming dynamics and a simpler analysis of its characteristics.

  5. Dynamic analysis program for frame structure

    International Nuclear Information System (INIS)

    Ando, Kozo; Chiba, Toshio

    1975-01-01

    A general purpose computer program named ISTRAN/FD (Isub(HI) STRucture ANalysis/Frame structure, Dynamic analysis) has been developed for dynamic analysis of three-dimensional frame structures. This program has functions of free vibration analysis, seismic response analysis, graphic display by plotter and CRT, etc. This paper introduces ISTRAN/FD; examples of its application are shown with various problems : idealization of the cantilever, dynamic analysis of the main tower of the suspension bridge, three-dimensional vibration in the plate girder bridge, seismic response in the boiler steel structure, and dynamic properties of the underground LNG tank. In this last example, solid elements, in addition to beam elements, are especially used for the analysis. (auth.)

  6. Receiver operator characteristic (ROC) analysis without truth

    International Nuclear Information System (INIS)

    Henkelman, R.M.; Kay, I.; Bronskill, M.J.

    1990-01-01

    Receiver operator characteristic (ROC) analysis, the preferred method of evaluating diagnostic imaging tests, requires an independent assessment of the true state of disease, which can be difficult to obtain and is often of questionable accuracy. A new method of analysis is described which does not require independent truth data and which can be used when several accurate tests are being compared. This method uses correlative information to estimate the underlying model of multivariate normal distributions of disease-positive and disease-negative patients. The method is shown to give results equivalent to conventional ROC analysis in a comparison of computed tomography, radionuclide scintigraphy, and magnetic resonance imaging for liver metastasis. When independent truth is available, the method can be extended to incorporate truth data or to evaluate the consistency of the truth data with the imaging data

  7. Analysis of physical characteristics of vegetable oils

    Energy Technology Data Exchange (ETDEWEB)

    Piamba Tulcan, Oscar Edwin [Universidade Nacional da Colombia (UNAL), Bogota (Colombia). Fac. de Ingenieria; Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica], E-mail: oepiambat@unal.edu.co; Andrade, Danielle Oliveira de; Andrade, Ednilton Tavares de [Universidade Federal Fluminense (TER/UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Agricola e do Meio Ambiente; Pereira, Roberto Guimaraes [Universidade Federal Fluminense (TER/UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Mecanica

    2008-07-01

    Different vegetable oils were characterized using standardized methods. The evaluated characteristics were density, viscosity, flow point, cloud point and corrosion. The obtained data was tabulated and compared with average composition values of oils in percentage of fatty acids and iodine number for each oil. In this analysis it is shown that viscosity decreases with the increase of the iodine number, and density decrease. The cloud and flow point have greater relation with the presence of saturated or highly unsaturated fatty acids, respectively. The index of corrosion is greater when oil saturation or its iodine number are increased. (author)

  8. Dynamic deformation and failure characteristic of rock foundation by means of effect of cyclic shear loading

    International Nuclear Information System (INIS)

    Fujiwara, Yoshikazu; Hibino, Satoshi; Kanagawa, Tadashi; Komada, Hiroya; Nakagawa, Kameichiro

    1984-01-01

    The main structures of nuclear power plants are built on hard and soft rocks. The rock-dynamic properties used for investigating the stability of the structures have been determined so far by laboratory tests for soft rocks. In hard rocks, however, joints and cracks exist, and the test including these effects is not able to be performed in laboratories at present. Therefore, a dynamic repeating shearing test equipment to be used under the condition including the joints and cracks of actual ground has been made for a base rock of tuff breccia. In this paper, the test results are reported as follows. The geological features of the testing site and the arrangement of tested rocks, the preparation for tests, test equipment, loading method, measuring method, analysis, and the result and the examination. The results of dynamic deformation and failure characteristics were as follows: (1) the dynamic shear-elasticity-modulus Gd of the base rock showed greater values as the normal stress increased, while Gd decreased and showed the strain dependence as the dynamic shear strain amplitude γ increased; (2) the relationship between Gd and γ was well represented with the equation proposed by Hardin-Drnevich; (3) damping ratio increased as γ increased, and decreased as normal stress increased; (4) When a specimen was about to break, γ suddenly increased, and the dynamic shear strain amplitude at yield point was in the range of approximately (3.4 to 4.1) x 10 -3 . (Wakatsuki, Y.)

  9. Dynamic-Stability Characteristics of Premixed Methane Oxy-Combustion

    KAUST Repository

    Shroll, Andrew P.

    2012-01-01

    This work explores the dynamic stability characteristics of premixed CH 4/O 2/CO 2 mixtures in a 50 kW swirl stabilized combustor. In all cases, the methane-oxygen mixture is stoichiometric, with different dilution levels of carbon dioxide used to control the flame temperature (T ad). For the highest T ad\\'s, the combustor is unstable at the first harmonic of the combustor\\'s natural frequency. As the temperature is reduced, the combustor jumps to fundamental mode and then to a low-frequency mode whose value is well below the combustor\\'s natural frequency, before eventually reaching blowoff. Similar to the case of CH 4/air mixtures, the transition from one mode to another is predominantly a function of the T ad of the reactive mixture, despite significant differences in laminar burning velocity and/or strained flame consumption speed between air and oxy-fuel mixtures for a given T ad. High speed images support this finding by revealing similar vortex breakdown modes and thus similar turbulent flame geometries that change as a function of flame temperature. Copyright © 2012 American Society of Mechanical Engineers.

  10. Dynamics Analysis of Unbalanced Motorized Spindles Supported on Ball Bearings

    Directory of Open Access Journals (Sweden)

    Junfeng Liu

    2016-01-01

    Full Text Available This paper presents an improved dynamic model for unbalanced high speed motorized spindles. The proposed model includes a Hertz contact force model which takes into the internal clearance and an unbalanced electromagnetic force model based on the energy of the air magnetic field. The nonlinear characteristic of the model is analysed by Lyapunov stability theory and numerical analysis to study the dynamic properties of the spindle system. Finally, a dynamic operating test is carried out on a DX100A-24000/20-type motorized spindle. The good agreement between the numerical solutions and the experimental data indicates that the proposed model is capable of accurately predicting the dynamic properties of motorized spindles. The influence of the unbalanced magnetic force on the system is studied, and the sensitivities of the system parameters to the critical speed of the system are obtained. These conclusions are useful for the dynamic design of high speed motorized spindles.

  11. Dynamic characteristics and structural response of the SWR 1000 under earthquake loading conditions

    International Nuclear Information System (INIS)

    Bielor, E.; Brettschuh, W.; Krutzik, N.J.; Tropp, R.

    2001-01-01

    Based on the conceptual design documentation of the SWR 1000 reactor building as well as specified representative seismological, and soil-dynamic input data, corresponding to prospective sites as a basis, the dynamic characteristics, as well as the in-structure dynamic response of the coupled vibrating structures have been elaborated. The structural design analysis was based on a 3-dimensional mathematical model of the building in which all details of the internal structures as well as the containment including the water in the pools were represented adequately. In order to demonstrate the influence of the soil-structure interaction effects on the dynamic response results, the soil was represented by two different assumptions. At first, considering the state of the art procedures, assuming frequency independent soil capabilities (equivalent stiffnesses and damping values), time domain calculations were carried out. In the second step, based on the frequency-dependency of the soil capabilities, frequency domain calculations were performed. The structural responses obtained by means of both procedures and the same mathematical model of the structures were evaluated and compared. The suitability of the preliminary design concept are discussed and the structural response results obtained on the basis of the bearing capacity and the stresses in the characteristic regions of the structure

  12. Dynamic Analysis of Composite Rotors

    Directory of Open Access Journals (Sweden)

    S. P. Singh

    1996-01-01

    accounted for. Material damping is also taken into account. The layerwise theory is compared with conventionally used equivalent modulus beam theory. Some interesting case studies are presented. The effect of various parameters on dynamic behavior and stability of a composite rotor is presented.

  13. Analysis of Nonlinear Dynamic Structures

    African Journals Online (AJOL)

    Bheema

    work a two degrees of freedom nonlinear system with zero memory was ... FRF is the most widely used method in structural dynamics which gives information about the ..... 3.6, which is the waterfall diagram of the same response, as well.

  14. The dynamic characteristics of HTGR (High Temperature Gas Cooled Reactor) system, (2)

    International Nuclear Information System (INIS)

    Kudo, Kazuhiko; Ohta, Masao; Kawasaki, Hidenori

    1979-01-01

    The dynamic characteristics of a HTGR plant, which has two cooling loops, was investigated. The analytical model consists of the core with fuel sleeves, coolant channels and blocks, the upper and lower reflectors, the high and low temperature plenums, two double wall pipings, two intermediate heat exchangers and the secondary system. The key plant parameters for calculation were as follows: the core outlet gas temperature 1000 deg C, the reactor thermal output 50 MW, the flow rate of primary coolant gas 7.96 kg/sec-loop and the pressure of primary coolant gas 40 kg/cm 2 at the rated operating condition. The calculating parameters were fixed as follows: the time interval for core characteristic analysis 0.1 sec, the time interval for thermal characteristic analysis 5.0 sec, the number of division of fuel channels 130, and the number of division of an intermediate heat exchanger 200. The assumptions for making the model were evaluated especially for the power distribution in the core and the heat transmission coefficients in the core, the double wall piping and the intermediate heat exchangers. Concerning the analytical results, the self-control to the outer disturbance of reactivity and the plant dynamic behavior due to the change of flow rate of primary and secondary coolants, and the change of gas temperature of secondary coolant at the inlet of intermediate heat exchangers, are presented. (Nakai, Y.)

  15. Dynamic characteristics of the thorax connected with the heart action.

    Science.gov (United States)

    Juznic, G; Emri, I; Peterec, D; Prepadnik, M

    1979-01-01

    We determined the indices of local vibrations (resonance frequency, damping coefficient, stiffness constant, extinction time) and transfer function H(s) . 10(-6) for three somatotypes and three respiratory positions on 88 points of the thorax. The examinees were males (age 21 years). We found the resonance frequencies of 36.86--54.75 cps, damping coefficient (delta) 0.121--0.217. This means the damping is less than critical (delta = 1). We applied shocks (a force of 2 N) with a reflex hammer on 88 points of the thorax. The force diminished from the exciting place (say ictus) to the recording place (accelerometer on the sternum) from 2 to 0.2 N. The athletic type has the highest resonance frequency and stiffness constant; the leptosomic type has the highest damping; the longest extinction time belongs to the pyknic type. The pyknic type has also the highest value of the transfer function. The respiratory position (quiet respiration, Valsalva and Müller experiment) influences the values of the indices of local vibrations and of the transfer function. The influence is evident especially on the intercostal points: the transfer of the oscillations is alleviated at a higher stiffness of the thorax (Valsalva; the value of H(S) . 10(-6) rises from 7.00 to 9.39 sec2), it deteriorates at a small stiffness of the thorax (in Müller's experiment falls to 2.78 sec2). With the fall in the intrathoracic pressure the damping in the intercostal points decreases. On the basis of experiments the conclusion was made that a short testing of the thorax of an examinee will give the dynamic characteristics of the thorax (indices of local vibrations and transfer functions) of the individual. This procedure will alleviate the quantitative use of noninvasive mechanical methods in the assessment of the cardiovascular function.

  16. A CAREM type fuel element dynamic analysis

    International Nuclear Information System (INIS)

    Magoia, J.E.

    1990-01-01

    A first analysis on the dynamic behaviour of a fuel element designed for the CAREM nuclear reactor (Central Argentina de Elementos Modulares) was performed. The model used to represent this dynamic behaviour was satisfactorily evaluated. Using primary estimations for some of its numerical parameters, a first approximation to its natural vibrational modes was obtained. Results obtained from fuel elements frequently used in nuclear power plants of the PWR (Pressurized Water Reactors) type, are compared with values resulting from similar analysis. (Author) [es

  17. Palo Verde nuclear dynamic analysis (PANDA)

    International Nuclear Information System (INIS)

    Girjashankar, P.V.; Secker, P.A. Jr.; LeClair, S.J.; Mendoza, J.; Webb, J.R.

    1988-01-01

    Arizona Nuclear Power Project (ANPP) has initiated the development of a large scale dynamic analysis computer program for the Palo Verde Nuclear Generating Station (PVNGS). This paper presents the decision processes and preliminary development activities that have been pursued related to the code development. The PANDA (Palo Verde Nuclear Dynamic Analysis) code will be used for a variety of applications as described in this paper

  18. Study on dynamic behavior analysis of towed line array sensor

    Directory of Open Access Journals (Sweden)

    Hyun Kyoung Shin

    2012-03-01

    Full Text Available A set of equations of motion is derived for vibratory motions of an underwater cable connected to a moving vehicle at one end and with drogues at the other end. From the static analysis, cable configurations are obtained for different vehicle speeds and towing pretensions are determined by fluid resistance of drogues. Also the dynamic analysis is required to predict its vibratory motion. Nonlinear fluid drag forces greatly influence the dynamic tension. In this study, a numerical analysis program was developed to find out the characteristic of cable behaviour. The motion is described in terms of space and time coordinates based on Chebyshev polynomial expansions. For the spatial integration the collocation method is employed and the Newmark method is applied for the time integration. Dynamic tensions, displacements, velocities, accelerations were predicted in the time domain while natural frequencies and transfer functions were obtained in the frequency domain.

  19. Data analysis for seismic motion characteristics

    International Nuclear Information System (INIS)

    Ishimaru, Tsuneari; Kohriya, Yorihide

    2002-10-01

    This data analysis is aimed at studying the characteristics of amplification of acceleration amplitude from deep underground to the surface, and is one of several continuous studies on the effects of earthquake motion. Seismic wave records were observed via a center array located in Shibata-cho, Miyagi Prefecture, which is part of the Kumagai-Gumi Array System for Strong Earthquake Motion (KASSEM) located on the Pacific coast in Miyagi and Fukushima Prefectures. Using acceleration waves obtained from earthquake observations, the amplification ratios of maximum acceleration amplitude and of root mean square acceleration amplitude which were based on the deepest observation point were estimated. Comparison between the seismic motion amplification characteristics of this study were made with the analyzed data at the Kamaishi-Mine (Kamaishi Miyagi Prefecture). The obtained results are as follows. The amplification ratios estimated from maximum acceleration amplitude and root mean square acceleration amplitude are almost constant in soft rock formations. However, amplification ratios at the surface in diluvium and alluvium are about three to four times larger than the ratios in soft rock formations. The amplification ratios estimated from root mean square acceleration amplitude are less dispersed than the ratios estimated from maximum acceleration amplitude. Comparing the results of this analysis with the results obtained at the Kamaishi-Mine, despite the difference in the rock types and the geologic formations at the observation points, there is a tendency for the amplification ratios at both points to be relatively small in the rock foundation and gradually increase toward the ground surface. (author)

  20. Mathematical analysis of dengue virus antibody dynamics

    Science.gov (United States)

    Perera, Sulanie; Perera, SSN

    2018-03-01

    Dengue is a mosquito borne viral disease causing over 390 million infections worldwide per annum. Even though information on how infection is controlled and eradicated from the body is lacking, antibodies are thought to play a major role in clearing the virus. In this paper, a non-linear conceptual dynamical model with humoral immune response and absorption effect has been proposed for primary dengue infection. We have included the absorption of pathogens into uninfected cells since this effect causes the virus density in the blood to decrease. The time delay that arises in the production of antibodies was accounted and is introduced through a continuous function. The basic reproduction number R0 is computed and a detailed stability analysis is done. Three equilibrium states, namely the infection free equilibrium, no immune equilibrium and the endemic equilibrium were identified and the existence and the stability conditions of these steady states were obtained. Numerical simulations proved the results that were obtained. By establishing the characteristic equation of the model at infection free equilibrium, it was observed that the infection free equilibrium is locally asymptotically stable if R0 1. Stability regions are identified for infection free equilibrium state with respect to the external variables and it is observed as the virus burst rate increases, the stability regions would decrease. These results implied that for higher virus burst rates, other conditions in the body must be strong enough to eliminate the disease completely from the host. The effect of time delay of antibody production on virus dynamics is discussed. It was seen that as the time delay in production of antibodies increases, the time for viral decline also increased. Also it was observed that the virus count goes to negligible levels within 7 - 14 days after the onset of symptoms as seen in dengue infections.

  1. Analysis of dynamic multiplicity fluctuations at PHOBOS

    Science.gov (United States)

    Chai, Zhengwei; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J. L.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A. H.; Wyslouch, B.

    2005-01-01

    This paper presents the analysis of the dynamic fluctuations in the inclusive charged particle multiplicity measured by PHOBOS for Au+Au collisions at surdsNN = 200GeV within the pseudo-rapidity range of -3 < η < 3. First the definition of the fluctuations observables used in this analysis is presented, together with the discussion of their physics meaning. Then the procedure for the extraction of dynamic fluctuations is described. Some preliminary results are included to illustrate the correlation features of the fluctuation observable. New dynamic fluctuations results will be available in a later publication.

  2. Session 6: Dynamic Modeling and Systems Analysis

    Science.gov (United States)

    Csank, Jeffrey; Chapman, Jeffryes; May, Ryan

    2013-01-01

    These presentations cover some of the ongoing work in dynamic modeling and dynamic systems analysis. The first presentation discusses dynamic systems analysis and how to integrate dynamic performance information into the systems analysis. The ability to evaluate the dynamic performance of an engine design may allow tradeoffs between the dynamic performance and operability of a design resulting in a more efficient engine design. The second presentation discusses the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a Simulation system with a library containing the basic building blocks that can be used to create dynamic Thermodynamic Systems. Some of the key features include Turbo machinery components, such as turbines, compressors, etc., and basic control system blocks. T-MAT is written in the Matlab-Simulink environment and is open source software. The third presentation focuses on getting additional performance from the engine by allowing the limit regulators only to be active when a limit is danger of being violated. Typical aircraft engine control architecture is based on MINMAX scheme, which is designed to keep engine operating within prescribed mechanical/operational safety limits. Using a conditionally active min-max limit regulator scheme, additional performance can be gained by disabling non-relevant limit regulators

  3. Dynamic response characteristics evaluation of hydrostatic bearing in hydraulic piston pump/motor

    International Nuclear Information System (INIS)

    Ham, Young Bog; Yun, So Nam; Kim, Dong Soo; Choi, Byoung Oh; Kim, Sung Dong

    2001-01-01

    In swash plate type axial piston hydraulic pump and motor, the piston shoe is periodically pressurized with square function shape by supply pressure load as rotation of cylinder barrel. Therefore the recess pressure ono bottom part of piston shoe is suddenly increase through orifice in the piston shoe. In this study, we simulated that the frequency response of the recess pressure against with change of supply pressure with analysis tool. Also, we evaluate the dynamic response characteristics of overbalanced hydrostatic bearing with change of the orifice diameter

  4. Dynamic response characteristics of steel portal frames having semi-rigid joints under sinusoidal wave excitation

    Science.gov (United States)

    Bhatti, Abdul Qadir

    2017-12-01

    To demonstrate the characteristics of the nonlinear response of steel frames, an elastic dynamic response analysis of the semi-rigid frame is performed under the harmonic wave. The semi-rigid contact is represented by the alternating spring which is given stiffness by a three-parameter energy model which approaches the hysterical curve by hardening model. The properties of spectra and hysteric curves are presented. This study shows that (1) the greater the acceleration input capacitance the smaller the instant connection capability and the smaller is the response. (2) However, by allowing an extreme increase in capacitance input acceleration, response spectra can be increased as the contact stiffness results near zero.

  5. Dynamic characteristics of a novel damped outrigger system

    Science.gov (United States)

    Tan, Ping; Fang, Chuangjie; Zhou, Fulin

    2014-06-01

    This paper presents exact analytical solutions for a novel damped outrigger system, in which viscous dampers are vertically installed between perimeter columns and the core of a high-rise building. An improved analytical model is developed by modeling the effect of the damped outrigger as a general rotational spring acting on a Bernoulli-Euler beam. The equivalent rotational spring stiffness incorporating the combined effects of dampers and axial stiffness of perimeter columns is derived. The dynamic stiffness method (DSM) is applied to formulate the governing equation of the damped outrigger system. The accuracy and efficiency are verified in comparison with those obtained from compatibility equations and boundary equations. Parametric analysis of three non-dimensional factors is conducted to evaluate the influences of various factors, such as the stiffness ratio of the core to the beam, position of the damped outrigger, and the installed damping coefficient. Results show that the modal damping ratio is significantly influenced by the stiffness ratio of the core to the column, and is more sensitive to damping than the position of the damped outrigger. The proposed analytical model in combination with DSM can be extended to the study of structures with more outriggers.

  6. Dynamics of climatic characteristics influencing vegetation in Siberia

    International Nuclear Information System (INIS)

    Shulgina, Tamara M; Genina, Elena Yu; Gordov, Evgeny P

    2011-01-01

    The spatiotemporal pattern of the dynamics of surface air temperature and precipitation and those bioclimatic indices that are based upon factors which control vegetation cover are investigated. Surface air temperature and precipitation data are retrieved from the ECMWF ERA Interim reanalysis and APHRODITE JMA datasets, respectively, which were found to be the closest to the observational data. We created an archive of bioclimatic indices for further detailed studies of interrelations between local climate and vegetation cover changes, which include carbon uptake changes related to changes of vegetation types and amount, as well as with spatial shifts of vegetation zones. Meanwhile, analysis reveals significant positive trends of the growing season length accompanied by a statistically significant increase of the sums of the growing degree days and precipitation over the south of West Siberia. The trends hint at a tendency for an increase of vegetation ecosystems' productivity across the south of West Siberia (55°–60°N, 59°–84°E) in the past several decades and (if sustained) may lead to a future increase of vegetation productivity in this region.

  7. Kinematic/Dynamic Characteristics for Visual and Kinesthetic Virtual Environments

    Science.gov (United States)

    Bortolussi, Michael R. (Compiler); Adelstein, B. D.; Gold, Miriam

    1996-01-01

    Work was carried out on two topics of principal importance to current progress in virtual environment research at NASA Ames and elsewhere. The first topic was directed at maximizing the temporal dynamic response of visually presented Virtual Environments (VEs) through reorganization and optimization of system hardware and software. The final results of this portion of the work was a VE system in the Advanced Display and Spatial Perception Laboratory at NASA Ames capable of updating at 60 Hz (the maximum hardware refresh rate) with latencies approaching 30 msec. In the course of achieving this system performance, specialized hardware and software tools for measurement of VE latency and analytic models correlating update rate and latency for different system configurations were developed. The second area of activity was the preliminary development and analysis of a novel kinematic architecture for three Degree Of Freedom (DOF) haptic interfaces--devices that provide force feedback for manipulative interaction with virtual and remote environments. An invention disclosure was filed on this work and a patent application is being pursued by NASA Ames. Activities in these two areas are expanded upon below.

  8. Adaptation and learning: characteristic time scales of performance dynamics.

    Science.gov (United States)

    Newell, Karl M; Mayer-Kress, Gottfried; Hong, S Lee; Liu, Yeou-Teh

    2009-12-01

    A multiple time scales landscape model is presented that reveals structures of performance dynamics that were not resolved in the traditional power law analysis of motor learning. It shows the co-existence of separate processes during and between practice sessions that evolve in two independent dimensions characterized by time scales that differ by about an order of magnitude. Performance along the slow persistent dimension of learning improves often as much and sometimes more during rest (memory consolidation and/or insight generation processes) than during a practice session itself. In contrast, the process characterized by the fast, transient dimension of adaptation reverses direction between practice sessions, thereby significantly degrading performance at the beginning of the next practice session (warm-up decrement). The theoretical model fits qualitatively and quantitatively the data from Snoddy's [Snoddy, G. S. (1926). Learning and stability. Journal of Applied Psychology, 10, 1-36] classic learning study of mirror tracing and other averaged and individual data sets, and provides a new account of the processes of change in adaptation and learning. 2009 Elsevier B.V. All rights reserved.

  9. The dynamics of parabolic flight: Flight characteristics and passenger percepts

    Science.gov (United States)

    Karmali, Faisal; Shelhamer, Mark

    2008-09-01

    Flying a parabolic trajectory in an aircraft is one of the few ways to create freefall on Earth, which is important for astronaut training and scientific research. Here we review the physics underlying parabolic flight, explain the resulting flight dynamics, and describe several counterintuitive findings, which we corroborate using experimental data. Typically, the aircraft flies parabolic arcs that produce approximately 25 s of freefall (0 g) followed by 40 s of enhanced force (1.8 g), repeated 30-60 times. Although passengers perceive gravity to be zero, in actuality acceleration, and not gravity, has changed, and thus we caution against the terms "microgravity" and "zero gravity." Despite the aircraft trajectory including large (45°) pitch-up and pitch-down attitudes, the occupants experience a net force perpendicular to the floor of the aircraft. This is because the aircraft generates appropriate lift and thrust to produce the desired vertical and longitudinal accelerations, respectively, although we measured moderate (0.2 g) aft-ward accelerations during certain parts of these trajectories. Aircraft pitch rotation (average 3°/s) is barely detectable by the vestibular system, but could influence some physics experiments. Investigators should consider such details in the planning, analysis, and interpretation of parabolic-flight experiments.

  10. Influence of steam parameters on static and dynamic characteristics of labyrinth seal

    Directory of Open Access Journals (Sweden)

    HE Wenqiang

    2017-10-01

    Full Text Available [Objectives] In order to study the influence of working medium parameters on the static and dynamic characteristics of seals in turbomachinery,[Methods] a three-dimensional model of a labyrinth seal was created, and air and steam were applied in the numerical simulation. The Computational Fluid Dynamics (CFD method and a rotating frame were applied to analyze the influence of different steam parameters on the leakage characteristics and dynamic characteristic coefficients.[Results] The results show that great differences in leakage flow rate are apparent under different air and steam conditions, and the fluid-induced force shows linear and nonlinear variation with the increasing whirl speed. When the steam temperature increases, the system stability decreases as the dynamic characteristic coefficients change.[Conclusions] In consequence, working medium parameters are of great significance for turbine stability, and the influence of working medium parameters on the static and dynamic characteristics of seals should be given great attention in practical application.

  11. Dynamic characteristics of Semi-active Hydraulic Engine Mount Based on Fluid-Structure Interaction FEA

    Directory of Open Access Journals (Sweden)

    Tian Jiande

    2015-01-01

    Full Text Available A kind of semi-active hydraulic engine mount is studied in this paper. After careful analysis of its structure and working principle, the FEA simulation of it was divided into two cases. One is the solenoid valve is open, so the air chamber connects to the atmosphere, and Fluid-Structure Interaction was used. Another is the solenoid valve is closed, and the air chamber has pressure, so Fluid-Structure-Gas Interaction was used. The test of this semi-active hydraulic engine mount was carried out to compare with the simulation results, and verify the accuracy of the model. Then the dynamic characteristics-dynamic stiffness and damping angle were analysed by simulation and test. This paper provides theoretical support for the development and optimization of the semi-active hydraulic engine mount.

  12. Comparison of Dynamic Characteristics of Two Instrumented Tall Buildings

    DEFF Research Database (Denmark)

    Ventura, C.; Laverick, B.; Brincker, Rune

    2003-01-01

    attention to the three-dimensional nonlinear dynamic behaviour of tall buildings, so there is a need for these types of studies. The purpose of this paper is to study the dynamic properties of two well-instrumented tall steel frame buildings in Los Angeles, California. These building are within a few blocks...

  13. Piecewise nonlinear dynamic characteristics study of the control rod drive mechanism

    International Nuclear Information System (INIS)

    Shen Xiaoyao; Wang Feng

    2011-01-01

    Piecewise nonlinear dynamics of the control rod mechanism (CRDM), one of the critical components in PWR nuclear power plants, are studied for its lifting process in this paper. Firstly, equations of the electric circuit and the magnetic circuit are set up. Then based on the dynamic lifting process analysis of CRDM, its motion procedure is divided into three stages, and the coupled magnetic-electric-mechanical equation for each stage is derived. By combining the analytical solution method and the numerical simulation method, the piecewise nonlinear governing equations are solved. Finally, parameters which can illustrate the dynamic characteristics of CRDM, such as the magnetic force, the coil current, the armature displacement, the armature velocity and the acceleration are obtained and corresponding curves with the time are drawn and analyzed. The analysis results are confirmed by the test which proves the validity of our method. Work in this paper can be used for design and analysis as well as the site fault diagnosis of CRDM. (author)

  14. Optimization of time characteristics in activation analysis

    International Nuclear Information System (INIS)

    Gurvich, L.G.; Umaraliev, A.T.

    2006-01-01

    Full text: The activation analysis temporal characteristics optimization methods developed at present are aimed at determination of optimal values of the three important parameters - irradiation time, cooling time and measurement time. In the performed works, especially in [1-5] the activation analysis processes are described, the optimal values of optimization parameters are obtained from equations solved, and the computational results are given for these parameters for a number of elements. However, the equations presented in [2] were inaccurate, did not allow one to have optimization parameters results for one element content calculations, and it did not take into account background dependence of time. Therefore, we proposed modified equations to determine the optimal temporal parameters and iteration processes for the solution of these equations. It is well-known that the activity of studied sample during measurements does not change significantly, i.e. measurement time is much shorter than the half-life, thus the processes taking place can be described by the Poisson probability distribution, and in general case one can apply binomial distribution. The equation and iteration processes use in this research describe both probability distributions. Expectedly, the cooling time iteration expressions obtained for one element analysis case are similar for the both distribution types, as the optimised time values occurred to be of the same order as half-life values, whereas the cooling time, as we observed, depends on the ratio of the studied sample's peak value to the background peak, and can be significantly larger than the half-life value. This pattern is general, and can be derived from the optimized time expressions, which is supported by the experimental data on short-living isotopes [3,4]. For the isotopes with large half-lives, up to years, like cobalt-60, the cooling time values given in the above mentioned works are equal to months which, apparently

  15. provisional analysis of population dynamics

    Indian Academy of Sciences (India)

    Nicholas Mitchison

    2018-01-11

    Jan 11, 2018 ... Western populations covered by OMIM, or are so mediated to a lesser extent. This we attribute ... tlenecks affected southern Asia: a coalescence analysis of ... included comprehensive survey of previous work (Atkin- son et al.

  16. Effect of Friction-Induced Nonlinearity on OMA-Identified Dynamic Characteristics of Offshore Platform Models

    DEFF Research Database (Denmark)

    Friis, Tobias; Orfanos, Antonios; Katsanos, Evangelos

    The identification of the modal characteristics of engineering systems under operational conditions is commonly conducted with the use of the Operational Modal Analysis (OMA), being a class of useful tools employed within various fields of structural, mechanical as well as marine and naval...... engineering. The current OMA methods have been advanced on the basis of two fundamental, though, restrictive assumptions: (i) linearity and (ii) stationarity. Nevertheless, there are several applications that are inherently related to various nonlinear mechanisms, which, in turn, violate the two cornerstones...... of OMA and hence, question its robustness and efficiency. Along these lines, the current study addresses the effect of friction-induced nonlinearity on OMA-identified dynamic characteristics of an experimental set up consisting of a pair of reduced scale offshore platform models that are connected...

  17. THEORETICAL AND EXPERIMENTAL STUDY OF THE DYNAMIC CHARACTERISTICS OF AXIAL BLOOD PUMPS

    Directory of Open Access Journals (Sweden)

    G. P. Itkin

    2011-01-01

    Full Text Available The article presents a theoretical analysis of the dynamic interaction of the left ventricle assist axial pump and the cardiovascular system. It is shown the axial pumps are working in conditions «left ventricle- aorta» generates a pulsed flow. The slope of the flow-pressure characteristics determine the amplitude of the pulsation. Data are confirmed in the chronic experiments on the biological models with the extracorporeal connection of the pump. The possibility of using this characteristic for the develope of the automatic control systems to ensure adequate operation of the pump in range of the physical activity of a patient ‘s physical activity. 

  18. Analysis of force characteristics of a superconducting ball in a given magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jianhua, E-mail: liujianhua@mail.iee.ac.c [Institute of Electrical Engineering, Chinese Academy of Sciences, No. 6 Beiertiao, Zhongguancun, Beijing 100190 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Wang Qiuliang; Yan Luguang [Institute of Electrical Engineering, Chinese Academy of Sciences, No. 6 Beiertiao, Zhongguancun, Beijing 100190 (China)

    2009-07-01

    The electromagnetic force characteristics along Z direction of a superconducting ball levitated by spherical coils with shaping blocks are calculated based on a semi-analytical method. The calculating results from the semi-analytical method are compared with the finite element analysis (FEA) method through a calculation example. The method can be applied to further analysis of dynamic characteristics and parameter optimization in the suspension system.

  19. Dynamics and vibrations progress in nonlinear analysis

    CERN Document Server

    Kachapi, Seyed Habibollah Hashemi

    2014-01-01

    Dynamical and vibratory systems are basically an application of mathematics and applied sciences to the solution of real world problems. Before being able to solve real world problems, it is necessary to carefully study dynamical and vibratory systems and solve all available problems in case of linear and nonlinear equations using analytical and numerical methods. It is of great importance to study nonlinearity in dynamics and vibration; because almost all applied processes act nonlinearly, and on the other hand, nonlinear analysis of complex systems is one of the most important and complicated tasks, especially in engineering and applied sciences problems. There are probably a handful of books on nonlinear dynamics and vibrations analysis. Some of these books are written at a fundamental level that may not meet ambitious engineering program requirements. Others are specialized in certain fields of oscillatory systems, including modeling and simulations. In this book, we attempt to strike a balance between th...

  20. Dynamic characteristics of motor-gear system under load saltations and voltage transients

    Science.gov (United States)

    Bai, Wenyu; Qin, Datong; Wang, Yawen; Lim, Teik C.

    2018-02-01

    In this paper, a dynamic model of a motor-gear system is proposed. The model combines a nonlinear permeance network model (PNM) of a squirrel-cage induction motor and a coupled lateral-torsional dynamic model of a planetary geared rotor system. The external excitations including voltage transients and load saltations, as well as the internal excitations such as spatial effects, magnetic circuits topology and material nonlinearity in the motor, and time-varying mesh stiffness and damping in the planetary gear system are considered in the proposed model. Then, the simulation results are compared with those predicted by the electromechanical model containing a dynamic motor model with constant inductances. The comparison showed that the electromechanical system model with the PNM motor model yields more reasonable results than the electromechanical system model with the lumped-parameter electric machine. It is observed that electromechanical coupling effect can induce additional and severe gear vibrations. In addition, the external conditions, especially the voltage transients, will dramatically affect the dynamic characteristics of the electromechanical system. Finally, some suggestions are offered based on this analysis for improving the performance and reliability of the electromechanical system.

  1. Comparative analysis of safety related site characteristics

    International Nuclear Information System (INIS)

    Andersson, Johan

    2010-12-01

    This document presents a comparative analysis of site characteristics related to long-term safety for the two candidate sites for a final repository for spent nuclear fuel in Forsmark (municipality of Oesthammar) and in Laxemar (municipality of Oskarshamn) from the point of view of site selection. The analyses are based on the updated site descriptions of Forsmark /SKB 2008a/ and Laxemar /SKB 2009a/, together with associated updated repository layouts and designs /SKB 2008b and SKB 2009b/. The basis for the comparison is thus two equally and thoroughly assessed sites. However, the analyses presented here are focussed on differences between the sites rather than evaluating them in absolute terms. The document serves as a basis for the site selection, from the perspective of long-term safety, in SKB's application for a final repository. A full evaluation of safety is made for a repository at the selected site in the safety assessment SR-Site /SKB 2011/, referred to as SR-Site main report in the following

  2. Comparative analysis of safety related site characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Johan (ed.)

    2010-12-15

    This document presents a comparative analysis of site characteristics related to long-term safety for the two candidate sites for a final repository for spent nuclear fuel in Forsmark (municipality of Oesthammar) and in Laxemar (municipality of Oskarshamn) from the point of view of site selection. The analyses are based on the updated site descriptions of Forsmark /SKB 2008a/ and Laxemar /SKB 2009a/, together with associated updated repository layouts and designs /SKB 2008b and SKB 2009b/. The basis for the comparison is thus two equally and thoroughly assessed sites. However, the analyses presented here are focussed on differences between the sites rather than evaluating them in absolute terms. The document serves as a basis for the site selection, from the perspective of long-term safety, in SKB's application for a final repository. A full evaluation of safety is made for a repository at the selected site in the safety assessment SR-Site /SKB 2011/, referred to as SR-Site main report in the following

  3. Elasticplastic dynamic analysis of pipelines

    International Nuclear Information System (INIS)

    Veloso Filho, D.; Loula, A.F.D.; Guerreiro, J.N.C.

    1982-01-01

    A model for structural analysis of spatial pipelines constituted by material with perfect elastoplastic behavior and submmited to time dependence stress is presented. The spatial discretization is done using the Finite Element method, and for the time integration of movement equations an stable finite difference algorithm is used. (E.G.) [pt

  4. Seismic Dynamic Damage Characteristics of Vertical and Batter Pile-supported Wharf Structure Systems

    Directory of Open Access Journals (Sweden)

    Li Jiren

    2015-10-01

    Full Text Available Considering a typical steel pipe pile-supported wharf as the research object, finite element analytical models of batter and vertical pile structures were established under the same construction site, service, and geological conditions to investigate the seismic dynamic damage characteristics of vertical and batter pile-supported wharf structures. By the numerical simulation and the nonlinear time history response analysis of structure system and the moment–axial force relation curve, we analyzed the dynamic damage characteristics of the two different structures of batter and vertical piles under different seismic ground motions to provide reasonable basis and reference for designing and selecting a pile-supported wharf structure. Results showed that the axial force of batter piles was dominant in the batter pile structure and that batter piles could effectively bear and share seismic load. Under the seismic ground motion with peak ground acceleration (PGA of 350 Gal and in consideration of the factors of the design requirement of horizontal displacement, the seismic performance of the batter pile structure was better than that of the vertical pile structure. Under the seismic ground motion with a PGA of 1000 Gal, plastic failure occurred in two different structures. The contrastive analysis of the development of plastic damage and the absorption and dissipation for seismic energy indicated that the seismic performance of the vertical pile structure was better than that of the batter pile structure.

  5. Reliability Analysis of Dynamic Stability in Waves

    DEFF Research Database (Denmark)

    Søborg, Anders Veldt

    2004-01-01

    exhibit sufficient characteristics with respect to slope at zero heel (GM value), maximum leverarm, positive range of stability and area below the leverarm curve. The rule-based requirements to calm water leverarm curves are entirely based on experience obtained from vessels in operation and recorded......The assessment of a ship's intact stability is traditionally based on a semi-empirical deterministic concept that evaluates the characteristics of ship's calm water restoring leverarm curves. Today the ship is considered safe with respect to dynamic stability if its calm water leverarm curves...... accidents in the past. The rules therefore only leaves little room for evaluation and improvement of safety of a ship's dynamic stability. A few studies have evaluated the probability of ship stability loss in waves using Monte Carlo simulations. However, since this probability may be in the order of 10...

  6. Test Model for Dynamic Characteristics of a Cantilevered Simple Cylindrical Structure Submerged in a Liquid

    International Nuclear Information System (INIS)

    Park, Chang Gyu; Kim, Tae Sung; Kim, Hoe Woong; Kim, Jong Bum

    2013-01-01

    A coolant free surface level is dependent on the operating conditions, and thus the fluid added mass caused by contacting sodium with the structure affects the dynamic characteristic of the UIS. In this study, a numerical analysis model was proposed and a feasibility study was performed through structural testing. The dynamic characteristics for a simple cylindrical structure simulating the UIS outer cylinder will be tested. Currently, the FE analyses were carried out to confirm the effect of water chamber structure on the natural frequency of the test model. The submerged condition of a UIS cylinder affects its natural frequency. A test model of a simple cylindrical structure was prepared to conduct a dynamic test, and each structure component of the test equipment may affect the natural frequency. A cup-shaped cylindrical structure was applied to develop the numerical analysis method for a structure submerged in water and it was verified through a structural test. With this numerical analysis model, the effect of the water chamber material for a simple cylindrical structure was studied. The candidate materials for water chamber were acryl and 316SS with different thicknesses. Both materials showed a higher natural frequency than the reference model. A water chamber made of 316SS with a thick wall gave a closer result to the reference natural frequency than an acryl chamber. The expected natural frequency of the test facility has about a 4% difference based on the reference value, considering a water chamber with a 1 cm thickness. This result will be verified through an ongoing future structural test activity

  7. Prime implicants in dynamic reliability analysis

    International Nuclear Information System (INIS)

    Tyrväinen, Tero

    2016-01-01

    This paper develops an improved definition of a prime implicant for the needs of dynamic reliability analysis. Reliability analyses often aim to identify minimal cut sets or prime implicants, which are minimal conditions that cause an undesired top event, such as a system's failure. Dynamic reliability analysis methods take the time-dependent behaviour of a system into account. This means that the state of a component can change in the analysed time frame and prime implicants can include the failure of a component at different time points. There can also be dynamic constraints on a component's behaviour. For example, a component can be non-repairable in the given time frame. If a non-repairable component needs to be failed at a certain time point to cause the top event, we consider that the condition that it is failed at the latest possible time point is minimal, and the condition in which it fails earlier non-minimal. The traditional definition of a prime implicant does not account for this type of time-related minimality. In this paper, a new definition is introduced and illustrated using a dynamic flowgraph methodology model. - Highlights: • A new definition of a prime implicant is developed for dynamic reliability analysis. • The new definition takes time-related minimality into account. • The new definition is needed in dynamic flowgraph methodology. • Results can be represented by a smaller number of prime implicants.

  8. Modeling, Testing, and Characteristic Analysis of a Planetary Flywheel Inerter

    Directory of Open Access Journals (Sweden)

    Zheng Ge

    2018-01-01

    Full Text Available We propose the planetary flywheel inerter, which is a new type of ball screw inerter. A planetary flywheel consists of several planetary gears mounted on a flywheel bracket. When the flywheel bracket is driven by a screw and rotating, each planetary gear meshing with an outer ring gear generates a compound motion composed of revolution and rotation. Theoretical analysis shows that the output force of the planetary flywheel inerter is proportional to the relative acceleration of one terminal of the inerter to the other. Optimizing the gear ratio of the planetary gears to the ring gear allows the planetary flywheel to be lighter than its traditional counterpart, without any loss on the inertance. According to the structure of the planetary flywheel inerter, nonlinear factors of the inerter are analyzed, and a nonlinear dynamical model of the inerter is established. Then the parameters in the model are identified and the accuracy of the model is validated by experiment. Theoretical analysis and experimental data show that the dynamical characteristics of a planetary flywheel inerter and those of a traditional flywheel inerter are basically the same. It is concluded that a planetary flywheel can completely replace a traditional flywheel, making the inerter lighter.

  9. Dynamic response analysis of DFB fibre lasers

    DEFF Research Database (Denmark)

    Yujun, Qian; Varming, Poul; Povlsen, Jørn Hedegaard

    1998-01-01

    We present a model for relative intensity noise (RIN) in DFB fibre lasers which predicts measured characteristics accurately. Calculation results implies that the RIN decreases rapidly with stronger Bragg grating and higher pump power. We propose here a simplified model based on three spatially...... independent rate equations to describe the dynamic response of erbium doped DFB fibre lasers on pump power fluctuations, using coupled-mode theory to calculate the steady-state hole-burning of the erbium ion inversion...

  10. Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y. [Seoul National Univ., Seoul (Korea, Republic of)

    2014-05-15

    precisely by the valve manufacturer. As a matter of fact, attempts were made to obtain flow characteristic curves resorting to analytical as well as numerical methods. The flow characteristic curve relates the stem lift with mass flow rate at a specific temperature and pressure. This paper focuses on computational and numerical analysis of the combined stop and control valve. Combined Airflow Regulation Analysis (CARA) is performed to check on the hydrodynamic characteristic, which is represented by flow coefficient characteristic. CATIA V.5 and ANSYS CFX are used for three-dimensional computer-aided design and computational fluid dynamics (CFD) analysis, respectively. Flow characteristic curves are plotted by calculating theoretical and numerical mass flow rate. Hydrodynamic analysis was made of the combined stop and control valve for the turbine system using ANSYS CFX. The result of the numerical study represented by the valve flow coefficient with different normalized values of valve stem movement L/D and different pressure ratios of valve outlet and inlet agrees well with the ideal case and other similar previous experimental results. This study also provided a solid understanding with versatile options for analyzing the hydrodynamics of the combined valve considering the various internal geometry, seat, plug, and the inlet plus outlet boundary conditions to improve the efficiency, performance and reliability of the turbine system of small as well as large power conversion system using the numerical analysis with minimal cost and time.

  11. Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System

    International Nuclear Information System (INIS)

    Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y.

    2014-01-01

    precisely by the valve manufacturer. As a matter of fact, attempts were made to obtain flow characteristic curves resorting to analytical as well as numerical methods. The flow characteristic curve relates the stem lift with mass flow rate at a specific temperature and pressure. This paper focuses on computational and numerical analysis of the combined stop and control valve. Combined Airflow Regulation Analysis (CARA) is performed to check on the hydrodynamic characteristic, which is represented by flow coefficient characteristic. CATIA V.5 and ANSYS CFX are used for three-dimensional computer-aided design and computational fluid dynamics (CFD) analysis, respectively. Flow characteristic curves are plotted by calculating theoretical and numerical mass flow rate. Hydrodynamic analysis was made of the combined stop and control valve for the turbine system using ANSYS CFX. The result of the numerical study represented by the valve flow coefficient with different normalized values of valve stem movement L/D and different pressure ratios of valve outlet and inlet agrees well with the ideal case and other similar previous experimental results. This study also provided a solid understanding with versatile options for analyzing the hydrodynamics of the combined valve considering the various internal geometry, seat, plug, and the inlet plus outlet boundary conditions to improve the efficiency, performance and reliability of the turbine system of small as well as large power conversion system using the numerical analysis with minimal cost and time

  12. Characteristics analysis of salt vacuum distillation equipment

    International Nuclear Information System (INIS)

    Im, Hun Suk; Oh, Seung Chul; Hong, Sun Seok; Hur, Jin Mok; Lee, Hyo Jik

    2016-01-01

    A new technique for pyroprocessing was designed by adding an oxide reduction process to the previous one. It is regarded as a promising process to treat and recycle oxide spent fuels owing to its enhanced nuclear proliferation resistance and the simplified process equipment and the low process costing. Spent oxide fuel is reduced into a metal by an electrochemical method while using a high-temperature molten salt as the reaction medium. After being subjected to electrorefining and electrowinning processes, the reduced metal fuel can be used in sodium-cooled fast reactors. The salt vacuum distillation process termed cathode processing follows the oxide reduction stage and has been developed to remove the residual salt, allowing for clear fuel metal to be supplied to the next step, which is electrorefining. KAERI has manufactured this apparatus in several sizes and has been able to achieve a fuel recovery rate of 95%. However it is very difficult to scale up the equipment. Because all transport phenomena, including heat transfer and fluid flow, depend on the size and structure of the apparatus used. The ideal method for overcoming this issue is nondimensionalization, which allows one to determine the characteristic properties of a system. A comparison of the dimensionless variables corresponding to the M-type and P-type apparatuses performed on the basis of phase-transition phenomena as well as the results of the above-mentioned analysis elucidated the differences between the two apparatuses. It also means that the structure of the nozzle throat can be the one of the several causes for the recovery performance. First, the standard model (i.e., the M-type apparatus) was analyzed using dimensionless parameters. The characteristics of this apparatus were the following: 1) the diameter of the outlet of the nozzle throat was twice that of the inlet, 2) the ratio of the length to the diameter (L/D) was 8, and 3) the modified heat-transfer factor was 220-270. It indicates

  13. Characteristics analysis of salt vacuum distillation equipment

    Energy Technology Data Exchange (ETDEWEB)

    Im, Hun Suk; Oh, Seung Chul; Hong, Sun Seok; Hur, Jin Mok; Lee, Hyo Jik [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    A new technique for pyroprocessing was designed by adding an oxide reduction process to the previous one. It is regarded as a promising process to treat and recycle oxide spent fuels owing to its enhanced nuclear proliferation resistance and the simplified process equipment and the low process costing. Spent oxide fuel is reduced into a metal by an electrochemical method while using a high-temperature molten salt as the reaction medium. After being subjected to electrorefining and electrowinning processes, the reduced metal fuel can be used in sodium-cooled fast reactors. The salt vacuum distillation process termed cathode processing follows the oxide reduction stage and has been developed to remove the residual salt, allowing for clear fuel metal to be supplied to the next step, which is electrorefining. KAERI has manufactured this apparatus in several sizes and has been able to achieve a fuel recovery rate of 95%. However it is very difficult to scale up the equipment. Because all transport phenomena, including heat transfer and fluid flow, depend on the size and structure of the apparatus used. The ideal method for overcoming this issue is nondimensionalization, which allows one to determine the characteristic properties of a system. A comparison of the dimensionless variables corresponding to the M-type and P-type apparatuses performed on the basis of phase-transition phenomena as well as the results of the above-mentioned analysis elucidated the differences between the two apparatuses. It also means that the structure of the nozzle throat can be the one of the several causes for the recovery performance. First, the standard model (i.e., the M-type apparatus) was analyzed using dimensionless parameters. The characteristics of this apparatus were the following: 1) the diameter of the outlet of the nozzle throat was twice that of the inlet, 2) the ratio of the length to the diameter (L/D) was 8, and 3) the modified heat-transfer factor was 220-270. It indicates

  14. Dynamic response analysis of the PSE torus

    International Nuclear Information System (INIS)

    Arthur, D.F.

    1977-01-01

    The paper describes a structural dynamic analysis of the 1 / 5 -scale BWR toroidal wetwell. The subscale toroidal wetwell is part of the Pressure Suppression Experiment Facility at Lawrence Livermore Laboratory. The analysis objective is to show that experimental structural loads measured by load cells in the wetwell supports are consistent with the internal hydrodynamic forcing function measured by pressure transducers. Finite element analysis of the wetwell indicates that the load and pressure measurements are consistent

  15. Improving the Dynamic Characteristics of Body-in-White Structure Using Structural Optimization

    Directory of Open Access Journals (Sweden)

    Aizzat S. Yahaya Rashid

    2014-01-01

    Full Text Available The dynamic behavior of a body-in-white (BIW structure has significant influence on the noise, vibration, and harshness (NVH and crashworthiness of a car. Therefore, by improving the dynamic characteristics of BIW, problems and failures associated with resonance and fatigue can be prevented. The design objectives attempt to improve the existing torsion and bending modes by using structural optimization subjected to dynamic load without compromising other factors such as mass and stiffness of the structure. The natural frequency of the design was modified by identifying and reinforcing the structure at critical locations. These crucial points are first identified by topology optimization using mass and natural frequencies as the design variables. The individual components obtained from the analysis go through a size optimization step to find their target thickness of the structure. The thickness of affected regions of the components will be modified according to the analysis. The results of both optimization steps suggest several design modifications to achieve the target vibration specifications without compromising the stiffness of the structure. A method of combining both optimization approaches is proposed to improve the design modification process.

  16. Structural Dynamics and Data Analysis

    Science.gov (United States)

    Luthman, Briana L.

    2013-01-01

    This project consists of two parts, the first will be the post-flight analysis of data from a Delta IV launch vehicle, and the second will be a Finite Element Analysis of a CubeSat. Shock and vibration data was collected on WGS-5 (Wideband Global SATCOM- 5) which was launched on a Delta IV launch vehicle. Using CAM (CAlculation with Matrices) software, the data is to be plotted into Time History, Shock Response Spectrum, and SPL (Sound Pressure Level) curves. In this format the data is to be reviewed and compared to flight instrumentation data from previous flights of the same launch vehicle. This is done to ensure the current mission environments, such as shock, random vibration, and acoustics, are not out of family with existing flight experience. In family means the peaks on the SRS curve for WGS-5 are similar to the peaks from the previous flights and there are no major outliers. The curves from the data will then be compiled into a useful format so that is can be peer reviewed then presented before an engineering review board if required. Also, the reviewed data will be uploaded to the Engineering Review Board Information System (ERBIS) to archive. The second part of this project is conducting Finite Element Analysis of a CubeSat. In 2010, Merritt Island High School partnered with NASA to design, build and launch a CubeSat. The team is now called StangSat in honor of their mascot, the mustang. Over the past few years, the StangSat team has built a satellite and has now been manifested for flight on a SpaceX Falcon 9 launch in 2014. To prepare for the final launch, a test flight was conducted in Mojave, California. StangSat was launched on a Prospector 18D, a high altitude rocket made by Garvey Spacecraft Corporation, along with their sister satellite CP9 built by California Polytechnic University. However, StangSat was damaged during an off nominal landing and this project will give beneficial insights into what loads the CubeSat experienced during the crash

  17. Elastic, Frictional, Strength and Dynamic Characteristics of the Bell Shape Shock Absorbers Made of MR Wire Material

    Science.gov (United States)

    Lazutkin, G. V.; Davydov, D. P.; Boyarov, K. V.; Volkova, T. V.

    2018-01-01

    The results of the mechanical characteristic experimental studies are presented for the shock absorbers of DKU type with the elastic elements of the bell shape made of MR material and obtained by the cold pressing of mutually crossing wire spirals with their inclusion in the array of reinforcing wire harnesses. The design analysis and the technology of MR production based on the methods of similarity theory and dimensional analysis revealed the dimensionless determined and determining parameters of elastic frictional, dynamic and strength characteristics under the static and dynamic loading of vibration isolators. The main similarity criteria of mechanical characteristics for vibration isolators and their graphical and analytical representation are determined, taking into account the coefficients of these (affine) transformations of the hysteresis loop family field.

  18. Dynamical analysis of tachyonic chameleon

    Science.gov (United States)

    Banijamali, Ali; Solbi, Milad

    2017-08-01

    In the present paper we investigate tachyonic chameleon scalar field and present the phase space analysis for four different combinations of the tachyonic potential V(φ ) and the coupling function f(φ ) of the chameleon field with matter. We find some stable solution in which accelerated expansion of the universe is satisfied. In one case where both f(φ ) and V(φ ) are exponential a scaling attractor was found that can give rise to the late-time acceleration of the universe and alleviate the coincidence problem.

  19. Dynamic Event Tree Analysis Through RAVEN

    Energy Technology Data Exchange (ETDEWEB)

    A. Alfonsi; C. Rabiti; D. Mandelli; J. Cogliati; R. A. Kinoshita; A. Naviglio

    2013-09-01

    Conventional Event-Tree (ET) based methodologies are extensively used as tools to perform reliability and safety assessment of complex and critical engineering systems. One of the disadvantages of these methods is that timing/sequencing of events and system dynamics is not explicitly accounted for in the analysis. In order to overcome these limitations several techniques, also know as Dynamic Probabilistic Risk Assessment (D-PRA), have been developed. Monte-Carlo (MC) and Dynamic Event Tree (DET) are two of the most widely used D-PRA methodologies to perform safety assessment of Nuclear Power Plants (NPP). In the past two years, the Idaho National Laboratory (INL) has developed its own tool to perform Dynamic PRA: RAVEN (Reactor Analysis and Virtual control ENvironment). RAVEN has been designed in a high modular and pluggable way in order to enable easy integration of different programming languages (i.e., C++, Python) and coupling with other application including the ones based on the MOOSE framework, developed by INL as well. RAVEN performs two main tasks: 1) control logic driver for the new Thermo-Hydraulic code RELAP-7 and 2) post-processing tool. In the first task, RAVEN acts as a deterministic controller in which the set of control logic laws (user defined) monitors the RELAP-7 simulation and controls the activation of specific systems. Moreover, RAVEN also models stochastic events, such as components failures, and performs uncertainty quantification. Such stochastic modeling is employed by using both MC and DET algorithms. In the second task, RAVEN processes the large amount of data generated by RELAP-7 using data-mining based algorithms. This paper focuses on the first task and shows how it is possible to perform the analysis of dynamic stochastic systems using the newly developed RAVEN DET capability. As an example, the Dynamic PRA analysis, using Dynamic Event Tree, of a simplified pressurized water reactor for a Station Black-Out scenario is presented.

  20. Dynamic analysis and design of offshore structures

    CERN Document Server

    Chandrasekaran, Srinivasan

    2015-01-01

    This book  attempts to provide readers with an overall idea of various types of offshore platform geometries. It covers the various environmental loads encountered by these structures, a detailed description of the fundamentals of structural dynamics in a class-room style, estimate of damping in offshore structures and their applications in the preliminary analysis and design. Basic concepts of structural dynamics are emphasized through simple illustrative examples and exercises. Design methodologies and guidelines, which are FORM based concepts are explained through a few applied example structures. Each chapter also has tutorials and exercises for self-learning. A dedicated chapter on stochastic dynamics will help the students to extend the basic concepts of structural dynamics to this advanced domain of research. Hydrodynamic response of offshore structures with perforated members is one of the recent research applications, which is found to be one of the effective manner of retrofitting offshore structur...

  1. Dynamics Analysis for Hydroturbine Regulating System Based on Matrix Model

    Directory of Open Access Journals (Sweden)

    Jiafu Wei

    2017-01-01

    Full Text Available The hydraulic turbine model is the key factor which affects the analysis precision of the hydraulic turbine governing system. This paper discusses the basic principle of the hydraulic turbine matrix model and gives two methods to realize. Using the characteristic matrix to describe unit flow and torque and their relationship with the opening and unit speed, it can accurately represent the nonlinear characteristics of the turbine, effectively improve the convergence of simulation process, and meet the needs of high precision real-time simulation of power system. Through the simulation of a number of power stations, it indicates that, by analyzing the dynamic process of the hydraulic turbine regulating with 5-order matrix model, the calculation results and field test data will have good consistency, and it can better meet the needs of power system dynamic simulation.

  2. Voltage stability analysis considering the load dynamic characteristics and the voltage control devices; Analisis de estabilidad de voltaje considerando las caracteristicas dinamicas de la carga y dispositivos de control de voltaje

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Alvarez, Enrique

    2001-09-15

    The research work presented in this thesis, is centered in the voltage stability analysis of medium term considering the effect of the load characteristics and its interaction with the voltage control device models in the transmission network. More concretely, a type of load model is defined and studied with desirable characteristics for the study of the voltage stability, the generic load models derived from field tests and from the application of identification techniques and it is analyzed the influence of the application of control systems to improve the system stability margins. Also, alternatives to the power system modeling for the voltage stability study in complex systems are reviewed. In the first place a fundamental analysis of the voltage characteristics and stability in a simplified power system is presented and the method of adopted analysis is introduced. It is shown that the instability phenomenon is manifested as a singular type bifurcation induced from the critical way of voltage when the system is operated under stress conditions. Next, the contribution of the action of the control devices to the stability margin is analyzed and criteria of the stability analyses are deducted based on the study of such mode. Following a linear model of the power system with desirable characteristics for the study of the voltage stability of medium term is proposed and the characteristics of stability in the context of the study of complex systems are interpreted. The proposed analysis tool is based on the physical notion that the behavior of the voltage control systems in the generators is very rapid with regard to the behavior of the load and has its main application in the preliminary study of the voltage stability of medium and long term. From this model, an analytical tool based on the application of techniques of linear analysis is proposed to approach the problem of determination of critical voltage areas and the contribution of control devices to the

  3. Gas-liquid reactor / separator: dynamics and operability characteristics

    NARCIS (Netherlands)

    Ranade, V.; Kuipers, J.A.M.; Versteeg, Geert

    1999-01-01

    A comprehensive mathematical model is developed to simulate gas¿liquid reactor in which both, reactants as well as products enter or leave the reactor in gas phase while the reactions take place in liquid phase. A case of first-order reaction (isothermal) was investigated in detail using the dynamic

  4. Dynamic and thermodynamic characteristics associated with the glass transition of amorphous trehalose-water mixtures.

    Science.gov (United States)

    Weng, Lindong; Elliott, Gloria D

    2014-06-21

    The glass transition temperature Tg of biopreservative formulations is important for predicting the long-term storage of biological specimens. As a complementary tool to thermal analysis techniques, which are the mainstay for determining Tg, molecular dynamics simulations have been successfully applied to predict the Tg of several protectants and their mixtures with water. These molecular analyses, however, rarely focused on the glass transition behavior of aqueous trehalose solutions, a subject that has attracted wide scientific attention via experimental approaches. Important behavior, such as hydrogen-bonding dynamics and self-aggregation has yet to be explored in detail, particularly below, or in the vicinity of, Tg. Using molecular dynamics simulations of several dynamic and thermodynamic properties, this study reproduced the supplemented phase diagram of trehalose-water mixtures (i.e., Tg as a function of the solution composition) based on experimental data. The structure and dynamics of the hydrogen-bonding network in the trehalose-water systems were also analyzed. The hydrogen-bonding lifetime was determined to be an order of magnitude higher in the glassy state than in the liquid state, while the constitution of the hydrogen-bonding network exhibited no noticeable change through the glass transition. It was also found that trehalose molecules preferred to form small, scattered clusters above Tg, but self-aggregation was substantially increased below Tg. The average cluster size in the glassy state was observed to be dependent on the trehalose concentration. Our findings provided insights into the glass transition characteristics of aqueous trehalose solutions as they relate to biopreservation.

  5. String Analysis for Dynamic Field Access

    DEFF Research Database (Denmark)

    Madsen, Magnus; Andreasen, Esben

    2014-01-01

    domains to reason about dynamic field access in a static analysis tool. A key feature of the domains is that the equal, concatenate and join operations take Ο(1) time. Experimental evaluation on four common JavaScript libraries, including jQuery and Prototype, shows that traditional string domains...

  6. Evaluating Dynamic Analysis Techniques for Program Comprehension

    NARCIS (Netherlands)

    Cornelissen, S.G.M.

    2009-01-01

    Program comprehension is an essential part of software development and software maintenance, as software must be sufficiently understood before it can be properly modified. One of the common approaches in getting to understand a program is the study of its execution, also known as dynamic analysis.

  7. Molecular dynamics investigation of the physisorption and interfacial characteristics of NBR chains on carbon nanotubes with different characteristics

    Directory of Open Access Journals (Sweden)

    Kun Li

    2017-07-01

    Full Text Available The present study investigates the physisorption and interfacial interactions between multiwalled carbon nanotubes (MWNTs with different characteristics, including different numbers of walls and different functional groups, and acrylonitrile-butadiene rubber (NBR polymer chains based on molecular dynamics simulations performed using modeled MWNT/NBR compound systems. The effects of the initial orientation of NBR chains and their relative distances to nanotubes, number of nanotube layers, and the surface functional groups of nanotubes on nanotube/polymer interactions are examined. Analysis is conducted according to the final configuration obtained in conjunction with the binding energy (Eb, radius of gyration (Rg and end-to-end distance (h. The results show that the final conformations of NBR chains adsorbed on MWNT surfaces is associated with the initial relative angle of the NBR chains and their distance from the nanotubes. For non-functionalized MWNTs, Eb is almost directly proportional to Rg under equivalent parameters. Moreover, it is observed that functional groups hinder the wrapping of NBR chains on the MWNT surfaces. This indicates that functional groups do not always benefit the macro-mechanical properties of the composites. Moreover, the type of the major interaction force has been dramatically changed into electrostatic force from vdW force because of functionalization.

  8. Molecular dynamics investigation of the physisorption and interfacial characteristics of NBR chains on carbon nanotubes with different characteristics

    Science.gov (United States)

    Li, Kun; Gu, Boqin

    2017-07-01

    The present study investigates the physisorption and interfacial interactions between multiwalled carbon nanotubes (MWNTs) with different characteristics, including different numbers of walls and different functional groups, and acrylonitrile-butadiene rubber (NBR) polymer chains based on molecular dynamics simulations performed using modeled MWNT/NBR compound systems. The effects of the initial orientation of NBR chains and their relative distances to nanotubes, number of nanotube layers, and the surface functional groups of nanotubes on nanotube/polymer interactions are examined. Analysis is conducted according to the final configuration obtained in conjunction with the binding energy (Eb), radius of gyration (Rg) and end-to-end distance (h). The results show that the final conformations of NBR chains adsorbed on MWNT surfaces is associated with the initial relative angle of the NBR chains and their distance from the nanotubes. For non-functionalized MWNTs, Eb is almost directly proportional to Rg under equivalent parameters. Moreover, it is observed that functional groups hinder the wrapping of NBR chains on the MWNT surfaces. This indicates that functional groups do not always benefit the macro-mechanical properties of the composites. Moreover, the type of the major interaction force has been dramatically changed into electrostatic force from vdW force because of functionalization.

  9. Vulcanization characteristics and dynamic mechanical behavior of natural rubber reinforced with silane modified silica.

    Science.gov (United States)

    Chonkaew, Wunpen; Minghvanish, Withawat; Kungliean, Ulchulee; Rochanawipart, Nutthaya; Brostow, Witold

    2011-03-01

    Two silane coupling agents were used for hydrolysis-condensation reaction modification of nanosilica surfaces. The surface characteristics were analyzed using Fourier transform infrared spectroscopy (FTIR). The vulcanization kinetics of natural rubber (NR) + silica composites was studied and compared to behavior of the neat NR using differential scanning calorimetry (DSC) in the dynamic scan mode. Dynamic mechanical analysis (DMA) was performed to evaluate the effects of the surface modification. Activation energy E(a) values for the reaction are obtained. The presence of silica, modified or otherwise, inhibits the vulcanization reaction of NR. The neat silica containing system has the lowest cure rate index and the highest activation energy for the vulcanization reaction. The coupling agent with longer chains causes more swelling and moves the glass transition temperature T(g) downwards. Below the glass transition region, silica causes a lowering of the dynamic storage modulus G', a result of hindering the cure reaction. Above the glass transition, silica-again modified or otherwise-provides the expected reinforcement effect.

  10. Dynamic characteristics of a cyclic-periodic structure with a piezoelectric network

    Directory of Open Access Journals (Sweden)

    Li Lin

    2015-10-01

    Full Text Available This paper deals with a cyclic-periodic structure with a piezoelectric network. In such a system, there is not only mechanical connection but also electrical connection between adjacent periodic sectors. The objective is to learn whether the presence of a piezoelectric network would change the dynamic characteristics of the system. The background of the research is about vibration reduction of a bladed disk in an aero-engine, and the system is simulated by a lumped parameter model. The dynamic equations of the system are derived, and then the analytical solution corresponding to the eigenvalue problem is given. The vibration responses to single traveling wave excitations (EO excitations and multiple traveling wave excitations (NEO excitations are studied. The results show that the presence of a piezoelectric network would change the natural frequencies of the system compared with those of the system with the piezoelectric shunt circuit. The forced response is sensitive to the connection type and the elements of the network. An energy analysis of the electro-mechanical coupling system has been performed to understand its dynamic behavior, and the following conclusion is obtained: a vibration reduction to excitations whose primary harmonic component is not zero can be achieved by a parallel piezoelectric network, while a reduction to other excitations should be based on a series piezoelectric network.

  11. Dynamic Characteristics of Micro-Beams Considering the Effect of Flexible Supports

    Directory of Open Access Journals (Sweden)

    Zuo-Yang Zhong

    2013-11-01

    Full Text Available Normally, the boundaries are assumed to allow small deflections and moments for MEMS beams with flexible supports. The non-ideal boundary conditions have a significant effect on the qualitative dynamical behavior. In this paper, by employing the principle of energy equivalence, rigorous theoretical solutions of the tangential and rotational equivalent stiffness are derived based on the Boussinesq’s and Cerruti’s displacement equations. The non-dimensional differential partial equation of the motion, as well as coupled boundary conditions, are solved analytically using the method of multiple time scales. The closed-form solution provides a direct insight into the relationship between the boundary conditions and vibration characteristics of the dynamic system, in which resonance frequencies increase with the nonlinear mechanical spring effect but decrease with the effect of flexible supports. The obtained results of frequencies and mode shapes are compared with the cases of ideal boundary conditions, and the differences between them are contrasted on frequency response curves. The influences of the support material property on the equivalent stiffness and resonance frequency shift are also discussed. It is demonstrated that the proposed model with the flexible supports boundary conditions has significant effect on the rigorous quantitative dynamical analysis of the MEMS beams. Moreover, the proposed analytical solutions are in good agreement with those obtained from finite element analyses.

  12. Nonlinear Dynamical Analysis for a Plain Bearing

    Directory of Open Access Journals (Sweden)

    Ali Belhamra

    2014-03-01

    Full Text Available This paper investigates the nonlinear dynamic behavior for a plain classic bearing (fluid bearing lubricated by a non-Newtonian fluid of a turbo machine rotating with high speed; this type of fluid contains additives viscosity (couple-stress fluid film. The solution of the nonlinear dynamic problem of this type of bearing is determined with a spatial discretisation of the modified Reynolds' equation written in dynamic mode by using the optimized short bearing theory and a temporal discretisation for equations of rotor motion by the help of Euler's explicit diagram. This study analyzes the dynamic behavior of a rotor supported by two couple-stress fluid film journal lubricant enhances the dynamic stability of the rotor-bearing system considerably compared to that obtained when using a traditional Newtonian lubricant. The analysis shows that the dynamic behavior of a shaft which turns with high velocities is strongly nonlinear even for poor eccentricities of unbalance; the presence of parameters of couple stress allows strongly attenuating the will synchrony (unbalance and asynchrony (whipping amplitudes of vibrations of the shaft which supports more severe conditions (large unbalances.

  13. Dynamic evolution characteristics of mining-induced fractures in overlying strata detected by radon

    International Nuclear Information System (INIS)

    Zhang Wei; Ma Liqiang; Wang Xufeng; Fang Gangwei; Zhang Dongsheng

    2011-01-01

    For environment protection in mining areas in northwest China, we developed a CTSRM (comprehensive test system by radon measurement) to measure radon radioactivity and detect dynamic evolution characteristics of mining-induced fractures in overlying strata. It was used to simulate the relationship between the dynamic evolution characteristics and radon concentrations of No. 33201 coalface at Bulianta coal mine in Inner Mongolia, and feasibility of the method was validate. (authors)

  14. Improvement of grid frequency dynamic characteristic with novel wind turbine based on electromagnetic coupler

    DEFF Research Database (Denmark)

    You, Rui; Barahona, Braulio; Chai, Jianyun

    2017-01-01

    . Additional power should be generated in response to a grid frequency drop in order to improve the dynamic characteristic of the grid frequency. In this paper, a novel control strategy for WT-EMC to improve the dynamic characteristic of grid frequency is proposed. The principle is to detect active power...... torque to stabilize the rotor speed, therefore directly improving the grid frequency. The proposed control strategy effectiveness is firstly tested through simulations and then validated on a specially built experimental platform....

  15. Cold starting characteristics analysis of hydraulic free piston engine

    International Nuclear Information System (INIS)

    Zhang, Shuanlu; Zhao, Zhenfeng; Zhao, Changlu; Zhang, Fujun; Wang, Shan

    2017-01-01

    The cold start characteristic of hydraulic free piston diesel engine may affect its stable operation. Therefore the specific cold start characteristics, such as BDC or TDC positions, pressure in-cylinder, heat release rate, should be investigated in detail. These parameters fluctuate in some regularity in the cod start process. With the development of the free piston engine prototype and the establishment of test bench, the results are obtained. For the dynamic results, the fluctuation range of TDC and BDC positions is 8 mm and decreases with time. The thermodynamic results show that the combustion process is not stable and the pressure in-cylinder fluctuates largely in the cold start process. In addition, the combustion is rapid and knock happens inevitably. In order to investigate the reasons, a CFD model is established for temperature analysis in-cylinder and heat transfer conditions. It is found that higher start wall temperature will lead to more uniform temperature distribution. The delay period may decreases and heat release will move forward. This reason is analyzed by thermodynamic derivation based on the first law of thermodynamics. Finally, the improvement suggestions of cold start strategy are proposed. - Highlights: • The cold start behaviors of HFPE are investigated in detail. • CFD method is used for simulating temperature distribution in start process. • Thermodynamic derivation uncovers the compression temperature distribution. • The improvement suggestions of cold start strategy are proposed.

  16. Major component analysis of dynamic networks of physiologic organ interactions

    International Nuclear Information System (INIS)

    Liu, Kang K L; Ma, Qianli D Y; Ivanov, Plamen Ch; Bartsch, Ronny P

    2015-01-01

    The human organism is a complex network of interconnected organ systems, where the behavior of one system affects the dynamics of other systems. Identifying and quantifying dynamical networks of diverse physiologic systems under varied conditions is a challenge due to the complexity in the output dynamics of the individual systems and the transient and nonlinear characteristics of their coupling. We introduce a novel computational method based on the concept of time delay stability and major component analysis to investigate how organ systems interact as a network to coordinate their functions. We analyze a large database of continuously recorded multi-channel physiologic signals from healthy young subjects during night-time sleep. We identify a network of dynamic interactions between key physiologic systems in the human organism. Further, we find that each physiologic state is characterized by a distinct network structure with different relative contribution from individual organ systems to the global network dynamics. Specifically, we observe a gradual decrease in the strength of coupling of heart and respiration to the rest of the network with transition from wake to deep sleep, and in contrast, an increased relative contribution to network dynamics from chin and leg muscle tone and eye movement, demonstrating a robust association between network topology and physiologic function. (paper)

  17. Blade row dynamic digital compression program. Volume 2: J85 circumferential distortion redistribution model, effect of Stator characteristics, and stage characteristics sensitivity study

    Science.gov (United States)

    Tesch, W. A.; Steenken, W. G.

    1978-01-01

    The results of dynamic digital blade row compressor model studies of a J85-13 engine are reported. The initial portion of the study was concerned with the calculation of the circumferential redistribution effects in the blade-free volumes forward and aft of the compression component. Although blade-free redistribution effects were estimated, no significant improvement over the parallel-compressor type solution in the prediction of total-pressure inlet distortion stability limit was obtained for the J85-13 engine. Further analysis was directed to identifying the rotor dynamic response to spatial circumferential distortions. Inclusion of the rotor dynamic response led to a considerable gain in the ability of the model to match the test data. The impact of variable stator loss on the prediction of the stability limit was evaluated. An assessment of measurement error on the derivation of the stage characteristics and predicted stability limit of the compressor was also performed.

  18. Impact parameter analysis and soft QCD dynamics

    International Nuclear Information System (INIS)

    Carvalho, P.A.S.; Martini, A.F.; Menon, M.J.

    2002-01-01

    In a recent paper, based on the hypothesis of light-cone dipole representation for gluon Bremsstrahlung, Kopeliovich et al. developed a dynamical model for the elastic hadronic amplitude. The model has been applied to pp and p (bar) p scattering and the effects of unitarity and peripheral interactions have been investigated in the impact parameter representation. In this communication, making use of a model independent extraction of the scattering amplitude in the impact parameter space (early developed), we represent a comparative study between the predictions from the dynamical model and the impact parameter analysis. (author)

  19. The characteristics of polysaccharides fractions of sunflower obtained in dynamic mode

    International Nuclear Information System (INIS)

    Makhkamov, Kh.K.; Gorshkova, R.M.; Khalikova, S.

    2013-01-01

    Present article describes characteristics of polysaccharides fractions of sunflower obtained in dynamic mode. The decomposition of sunflower pectin was studied by means of continuous fractionation method in dynamic regime. It was found that the process is of extreme nature due to heterogeneity of its macromolecule structure. The additional information on macromolecule structure of sunflower pectin was obtained.

  20. Dynamic characteristics of steam generator U-tubes with defect

    International Nuclear Information System (INIS)

    Jo, Jong Chull; Jhung, Myung Jo; Kim, Woong Sik; Kim, Hho Jung

    2005-01-01

    This study investigates the fluid elastic instability characteristics of steam generator (SG) U-tubes with defect and the safety assessment of the potential for fretting-wear damages caused by foreign object in operating nuclear power plants. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for the U-tubes either with axial or circumferential flaw with different sizes. Special emphases are on the effects of flaw orientation and size on the modal and instability characteristics of tubes, which are expressed in terms of the natural frequency, corresponding mode shape and stability ratio. Also, the wear rate of U-tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted, and discussed in this study is the effect of the flow velocity and vibration of the tube on the remaining life of the tube. In addition, addressed in this study is the effect of the internal pressure on the vibration and fretting-wear characteristics of the tube

  1. Flight Dynamics Analysis Branch 2005 Technical Highlights

    Science.gov (United States)

    2005-01-01

    This report summarizes the major activities and accomplishments carried out by the Flight Dynamics Analysis Branch (FDAB), Code 595, in support of flight projects and technology development initiatives in Fiscal Year (FY) 2005. The report is intended to serve as a summary of the type of support carried out by the FDAB, as well as a concise reference of key accomplishments and mission experience derived from the various mission support roles. The primary focus of the FDAB is to provide expertise in the disciplines of flight dynamics including spacecraft navigation (autonomous and ground based); spacecraft trajectory design and maneuver planning; attitude analysis; attitude determination and sensor calibration; and attitude control subsystem (ACS) analysis and design. The FDAB currently provides support for missions and technology development projects involving NASA, other government agencies, academia, and private industry.

  2. Characteristic dynamics near two coalescing eigenvalues incorporating continuum threshold effects

    Science.gov (United States)

    Garmon, Savannah; Ordonez, Gonzalo

    2017-06-01

    It has been reported in the literature that the survival probability P(t) near an exceptional point where two eigenstates coalesce should generally exhibit an evolution P (t ) ˜t2e-Γ t, in which Γ is the decay rate of the coalesced eigenstate; this has been verified in a microwave billiard experiment [B. Dietz et al., Phys. Rev. E 75, 027201 (2007)]. However, the heuristic effective Hamiltonian that is usually employed to obtain this result ignores the possible influence of the continuum threshold on the dynamics. By contrast, in this work we employ an analytical approach starting from the microscopic Hamiltonian representing two simple models in order to show that the continuum threshold has a strong influence on the dynamics near exceptional points in a variety of circumstances. To report our results, we divide the exceptional points in Hermitian open quantum systems into two cases: at an EP2A two virtual bound states coalesce before forming a resonance, anti-resonance pair with complex conjugate eigenvalues, while at an EP2B two resonances coalesce before forming two different resonances. For the EP2B, which is the case studied in the microwave billiard experiment, we verify that the survival probability exhibits the previously reported modified exponential decay on intermediate time scales, but this is replaced with an inverse power law on very long time scales. Meanwhile, for the EP2A the influence from the continuum threshold is so strong that the evolution is non-exponential on all time scales and the heuristic approach fails completely. When the EP2A appears very near the threshold, we obtain the novel evolution P (t ) ˜1 -C1√{t } on intermediate time scales, while further away the parabolic decay (Zeno dynamics) on short time scales is enhanced.

  3. Torque converter transient characteristics prediction using computational fluid dynamics

    International Nuclear Information System (INIS)

    Yamaguchi, T; Tanaka, K

    2012-01-01

    The objective of this research is to investigate the transient torque converter performance used in an automobile. A new technique in computational fluid dynamics is introduced, which includes the inertia of the turbine in a three dimensional simulation of the torque converter during a launch condition. The simulation results are compared to experimental test data with good agreement across the range of data. In addition, the simulated flow structure inside the torque converter is visualized and compared to results from a steady-state calculation.

  4. Two-dimensional simulation of the thermal stress effect on static and dynamic VDMOS characteristics

    International Nuclear Information System (INIS)

    Alwan, M.; Beydoun, B.; Ketata, K.; Zoaeter, M.

    2005-01-01

    Using a two-dimensional simulator, the effect of the thermal stress on static and dynamic vertical double-diffusion metal oxide semiconductor (VDMOS) characteristics have been investigated. The use of the device under certain thermal stress conditions can produce modifications of its physical and electrical properties. Based on physics and 2D simulations, this paper proposes an analysis of this stress effect observed on the electrical characteristics of the device. Parameters responsible of these modifications are determined. Approximate expressions of the ionization coefficients and breakdown voltage in terms of temperature are proposed. Non-punch-through junction theory is used to express the breakdown voltage and the space charge extension with respect to the impurity concentration and the temperature. The capacitances of the device have been also studied. The effect of the stress on C-V characteristics is observed and analyzed. We notice that the drain-gate, drain-source and gate-source capacitances are shifted due to the degradation of device physical properties versus thermal stress

  5. The method of the gas-dynamic centrifugal compressor stage characteristics recalculation for variable rotor rotational speeds and the rotation angle of inlet guide vanes blades if the kinematic and dynamic similitude conditions are not met

    Science.gov (United States)

    Vanyashov, A. D.; Karabanova, V. V.

    2017-08-01

    A mathematical description of the method for obtaining gas-dynamic characteristics of a centrifugal compressor stage is proposed, taking into account the control action by varying the rotor speed and the angle of rotation of the guide vanes relative to the "basic" characteristic, if the kinematic and dynamic similitude conditions are not met. The formulas of the correction terms for the non-dimensional coefficients of specific work, consumption and efficiency are obtained. A comparative analysis of the calculated gas-dynamic characteristics of a high-pressure centrifugal stage with experimental data is performed.

  6. Cluster analysis of word frequency dynamics

    Science.gov (United States)

    Maslennikova, Yu S.; Bochkarev, V. V.; Belashova, I. A.

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations.

  7. Integrability of dynamical systems algebra and analysis

    CERN Document Server

    Zhang, Xiang

    2017-01-01

    This is the first book to systematically state the fundamental theory of integrability and its development of ordinary differential equations with emphasis on the Darboux theory of integrability and local integrability together with their applications. It summarizes the classical results of Darboux integrability and its modern development together with their related Darboux polynomials and their applications in the reduction of Liouville and elementary integrabilty and in the center—focus problem, the weakened Hilbert 16th problem on algebraic limit cycles and the global dynamical analysis of some realistic models in fields such as physics, mechanics and biology. Although it can be used as a textbook for graduate students in dynamical systems, it is intended as supplementary reading for graduate students from mathematics, physics, mechanics and engineering in courses related to the qualitative theory, bifurcation theory and the theory of integrability of dynamical systems.

  8. Cluster analysis of word frequency dynamics

    International Nuclear Information System (INIS)

    Maslennikova, Yu S; Bochkarev, V V; Belashova, I A

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations

  9. Statistical analysis of dynamic parameters of the core

    International Nuclear Information System (INIS)

    Ionov, V.S.

    2007-01-01

    The transients of various types were investigated for the cores of zero power critical facilities in RRC KI and NPP. Dynamic parameters of neutron transients were explored by tool statistical analysis. Its have sufficient duration, few channels for currents of chambers and reactivity and also some channels for technological parameters. On these values the inverse period. reactivity, lifetime of neutrons, reactivity coefficients and some effects of a reactivity are determinate, and on the values were restored values of measured dynamic parameters as result of the analysis. The mathematical means of statistical analysis were used: approximation(A), filtration (F), rejection (R), estimation of parameters of descriptive statistic (DSP), correlation performances (kk), regression analysis(KP), the prognosis (P), statistician criteria (SC). The calculation procedures were realized by computer language MATLAB. The reasons of methodical and statistical errors are submitted: inadequacy of model operation, precision neutron-physical parameters, features of registered processes, used mathematical model in reactivity meters, technique of processing for registered data etc. Examples of results of statistical analysis. Problems of validity of the methods used for definition and certification of values of statistical parameters and dynamic characteristics are considered (Authors)

  10. Study on aero-dynamic characteristics of the sloop rig (continued); Sloop ring no kuriki tokusei no ichikaiseki (zoku)

    Energy Technology Data Exchange (ETDEWEB)

    Shinkai, A.; Iyoda, H. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1997-09-04

    A numerical simulation method was formerly provided for analyzing aero-dynamic characteristics of sloop rig by the vortex distribution method. For this method, aero-dynamic characteristics of the sloop rib were formulated by treating air flow around sail as a two-dimensional problem and by assuming sail as a membrane. The sloop rig is a yacht for more than two persons, which is the most popular form of rig. A main sail and a jib sheet are fixed on a mast. In this study, the method developed based on the panel method was introduced for analyzing the effects of jib sheet which can control the jib trim angle. Generality of the present aero-dynamic characteristics was enhanced, and problems of the analysis method were extracted through the numerical simulation of a yacht with sloop rig. Influence of the position of fairleader on the aero-dynamic characteristics was qualitatively grasped by considering the effects of jib sheet and by trimming the elevation into ideal one. 6 refs., 11 figs.

  11. Chemistry in interstellar space. [environment characteristics influencing reaction dynamics

    Science.gov (United States)

    Donn, B.

    1973-01-01

    The particular characteristics of chemistry in interstellar space are determined by the unique environmental conditions involved. Interstellar matter is present at extremely low densities. Large deviations from thermodynamic equilibrium are, therefore, to be expected. A relatively intense ultraviolet radiation is present in many regions. The temperatures are in the range from 5 to 200 K. Data concerning the inhibiting effect of small activation energies in interstellar clouds are presented in a table. A summary of measured activation energies or barrier heights for exothermic exchange reactions is also provided. Problems of molecule formation are discussed, taking into account gas phase reactions and surface catalyzed processes.

  12. Dynamic Performance Characteristics of a Curved Slider Bearing Operating with Ferrofluids

    Directory of Open Access Journals (Sweden)

    Udaya P. Singh

    2012-01-01

    Full Text Available In the present theoretical investigation, the effect of ferrofluid on the dynamic characteristics of curved slider bearings is presented using Shliomis model which accounts for the rotation of magnetic particles, their magnetic moments, and the volume concentration in the fluid. The modified Reynolds equation for the dynamic state of the bearing is obtained. The results of dynamic stiffness and damping characteristics are presented. It is observed that the effect of rotation of magnetic particles improves the stiffness and damping capacities of the bearings.

  13. Dynamic characteristics of Non Newtonian fluid Squeeze film damper

    Science.gov (United States)

    Palaksha, C. P.; Shivaprakash, S.; Jagadish, H. P.

    2016-09-01

    The fluids which do not follow linear relationship between rate of strain and shear stress are termed as non-Newtonian fluid. The non-Newtonian fluids are usually categorized as those in which shear stress depends on the rates of shear only, fluids for which relation between shear stress and rate of shear depends on time and the visco inelastic fluids which possess both elastic and viscous properties. It is quite difficult to provide a single constitutive relation that can be used to define a non-Newtonian fluid due to a great diversity found in its physical structure. Non-Newtonian fluids can present a complex rheological behaviour involving shear-thinning, viscoelastic or thixotropic effects. The rheological characterization of complex fluids is an important issue in many areas. The paper analyses the damping and stiffness characteristics of non-Newtonian fluids (waxy crude oil) used in squeeze film dampers using the available literature for viscosity characterization. Damping and stiffness characteristic will be evaluated as a function of shear strain rate, temperature and percentage wax concentration etc.

  14. Dynamic characteristic of intense short microwave propagation in an atmosphere

    International Nuclear Information System (INIS)

    Yee, J.H.; Alvarez, R.A.; Mayhall, D.J.; Madsen, N.K.; Cabayan, H.S.

    1983-07-01

    The dynamic behavior of an intense microwave pulse which propagates through the atmosphere will be presented. Our theoretical results are obtained by solving Maxwell's equations, together with the electron fluid equations. Our calculations show that although large portions of the initial energy are absorbed by the electrons that are created through the avalanche process, a significant amount of energy is still able to reach the earth's surface. The amount of energy that reaches the earth's surface as a function of initial energy and wave shape after having propagated through 100 km in the atmosphere are investigated. Results for the air breakdown threshold intensity as a function of the pressure for different pulse widths and different frequencies will also be presented. In addition, we will present a comparison between the theoretical and the experimental results for the pulse shape of a short microwave pulse after it has traveled through a rectangular wave guide which contains a section of air. 23 references, 9 figures

  15. Dynamic image characteristics of pulmonary tuberculosis with diabetes mellitus

    International Nuclear Information System (INIS)

    Zhou Xinhua

    2000-01-01

    Objective: To analyze image characteristics of pulmonary tuberculosis associated with diabetes mellitus and observe the changes of pulmonary tuberculotic lesions influenced by the state of hyperglycosemia. Methods: Examinations of chest plain film and tomography were taken in 68 patients with pulmonary tuberculosis and diabetes, and additional CT scans were done in 38 patients among them. Radiological examinations of lung and blood sugar test were taken at the interval of 2, 3, and 4-6 months in all 68 patients under the treatment of regular blood sugar control and antituberculosis, which compared with 30 patients with pulmonary tuberculosis only. Results: The images of X-ray and CT showed major lesions of massive patchy shadow in 55 patients (80.9%), or multiple small patchy shadow in 13(19.1%) and cavity 61(89.7%). After 2 month's treatment, enlargement of patchy shadow and cavity were found in 9(23.7%)and 10(28.6%)cases, respectively with overall deterioration rates of 65.8% in group of 38 patients with level of blood sugar over 7.0 mmol/L, which was significantly higher than that of the control group 7.0 mmol/L(x 2 =16.4, P 2 = 0.81, P>0.5) with the well controlled blood sugar after treatment of 3 months or more. The follow-up images showed similar results between the groups of pulmonary tuberculosis only and the group of pulmonary tuberculosis with high level of blood sugar, in which the overall deterioration rates was significant less than the group of pulmonary tuberculosis with level of blood sugar more than 8.0 mmol/L(x 2 =5.46, P<0.025). Conclusion: There are imaging characteristics in patient with pulmonary tuberculosis and diabetes mellitus. The state of hyperglycosemia is a vital factor, which influences the radiological changes of pulmonary tuberculosis

  16. A new nonlinear magnetic circuit model for dynamic analysis of interior permanent magnet synchronous motor

    International Nuclear Information System (INIS)

    Nakamura, Kenji; Saito, Kenichi; Watanabe, Tadaaki; Ichinokura, Osamu

    2005-01-01

    Interior permanent magnet synchronous motors (IPMSMs) have high efficiency and torque, since the motors can utilize reluctance torque in addition to magnet torque. The IPMSMs are widely used for electric household appliances and electric bicycles and vehicles. A quantitative analysis method of dynamic characteristics of the IPMSMs, however, has not been clarified fully. For optimum design, investigation of dynamic characteristics considering magnetic nonlinearity is needed. This paper presents a new nonlinear magnetic circuit model of an IPMSM, and suggests a dynamic analysis method using the proposed magnetic circuit model

  17. Piping dynamic analysis by the synthesis method

    International Nuclear Information System (INIS)

    Bezler, P.; Curreri, J.R.

    1976-01-01

    Since piping systems are a frequent source of noise and vibrations, their efficient dynamic analysis is imperative. As an alternate to more conventional analyses methods, an application of the synthesis method to piping vibrations analyses is demonstrated. Specifically, the technique is illustrated by determining the normal modes and natural frequencies of a composite bend from the normal mode and natural frequency data of two component parts. A comparison of the results to those derived for the composite bend by other techniques is made

  18. Dynamic nonlinear analysis of shells of revolution

    International Nuclear Information System (INIS)

    Riesemann, W.A. von; Stricklin, J.A.; Haisler, W.E.

    1975-01-01

    Over the past few years a series of finite element computer programs have been developed at Texas A and M University for the static and dynamic nonlinear analysis of shells of revolution. This paper discusses one of these, DYNAPLAS, which is a program for the transient response of ring stiffened shells of revolution subjected to either asymmetric initial velocities or to asymmetric pressure loadings. Both material and geometric nonlinearities may be considered. (Auth.)

  19. Simplified Dynamic Analysis of Grinders Spindle Node

    Science.gov (United States)

    Demec, Peter

    2014-12-01

    The contribution deals with the simplified dynamic analysis of surface grinding machine spindle node. Dynamic analysis is based on the use of the transfer matrix method, which is essentially a matrix form of method of initial parameters. The advantage of the described method, despite the seemingly complex mathematical apparatus, is primarily, that it does not require for solve the problem of costly commercial software using finite element method. All calculations can be made for example in MS Excel, which is advantageous especially in the initial stages of constructing of spindle node for the rapid assessment of the suitability its design. After detailing the entire structure of spindle node is then also necessary to perform the refined dynamic analysis in the environment of FEM, which it requires the necessary skills and experience and it is therefore economically difficult. This work was developed within grant project KEGA No. 023TUKE-4/2012 Creation of a comprehensive educational - teaching material for the article Production technique using a combination of traditional and modern information technology and e-learning.

  20. Analysis of the characteristics of competitive badminton

    Science.gov (United States)

    Cabello, M; Gonzalez-Badillo, J

    2003-01-01

    Objective: To describe the characteristics of badminton in order to determine the energy requirements, temporal structure, and movements in the game that indicate performance level. To use the findings to plan training with greater precision. Methods: Eleven badminton players (mean (SD) age 21.8 (3.26) years) with international experience from four different countries (France, Italy, Spain, and Portugal) were studied. Two of the Spanish players were monitored in several matches, giving a total of 14 samples, all during the 1999 Spanish International Tournament. Blood lactate concentration was measured with a reflective photometer. Maximum and average heart rates were recorded with a heart rate monitor. Temporal structure and actions during the matches were determined from video recordings. All variables were measured during and after the game and later analysed using a descriptive study. Results: The results confirmed the high demands of the sport, with a maximum heart rate of 190.5 beats/min and an average of 173.5 beats/min during matches over 28 minutes long and performance intervals of 6.4 seconds and rest time of 12.9 seconds between exchanges. Conclusions: The results suggest that badminton is characterised by repetitive efforts of alactic nature and great intensity which are continuously performed throughout the match. An awareness of these characteristics, together with data on the correlations between certain actions such as unforced errors and winning shots and the final result of the match, will aid in more appropriate planning and monitoring of specific training. PMID:12547746

  1. Nonlinear Coupling Characteristics Analysis of Integrated System of Electromagnetic Brake and Frictional Brake of Car

    Directory of Open Access Journals (Sweden)

    Ren He

    2015-01-01

    Full Text Available Since theoretical guidance is lacking in the design and control of the integrated system of electromagnetic brake and frictional brake, this paper aims to solve this problem and explores the nonlinear coupling characteristics and dynamic characteristics of the integrated system of electromagnetic brake and frictional brake. This paper uses the power bond graph method to establish nonlinear coupling mathematical model of the integrated system of electromagnetic brake and frictional brake and conducts the contrastive analysis on the dynamic characteristics based on this mathematical model. Meanwhile, the accuracy of the nonlinear coupling mathematical model proposed above is verified on the hardware in the loop simulation platform, and nonlinear coupling characteristics of the integrated system are also analyzed through experiments.

  2. Dynamic Characteristics of S-band DC SQUID Amplifier

    DEFF Research Database (Denmark)

    Prokopenko, G. V.; Shitov, S. V.; Koshelets, I. L. L. V. P.

    2003-01-01

    A low-noise rf amplifier based on a de SQUID (SQA) has been tested in the frequency range 3.0-4.6 GHz in the open-loop configuration. The following parameters have been measured for the single-stage balanced type SQA at 4.0 GHz: gain (12 +/- 1) dB, 3 dB bandwidth of 500 MHz and noise temperature (1.......0 +/- 0.25) K. For the nonbalanced type SQA at 4.0 GHz gain was (15 +/-1) dB, 3 dB bandwidth 200 MHz and noise temperature (0.5 +/- 0.25) K. The improved performance is obtained due to the increased characteristic voltage (approximate to 420 muV) of the small-area (down to 0.7-0.9 mum(2)) high-quality Nb......-AlOx-Nb SIS junctions. The saturation power (normalized to 1 GHz) referred to the input at 1 dB gain compression is estimated as approximate to55 K*GHz at a bias voltage of 60 muV. The reasons for saturation of the SQA are discussed....

  3. Relationships between Arctic shrub dynamics and topographically derived hydrologic characteristics

    International Nuclear Information System (INIS)

    Naito, Adam T; Cairns, David M

    2011-01-01

    Shrub expansion is a global phenomenon that is gaining increased attention in the Arctic. Recent work employing the use of oblique aerial photographs suggested a consistent pattern of positive change in shrub cover across the North Slope of Alaska. The greatest amounts of change occurred in valley slopes and floodplains. We studied the association between shrub cover change and topographically derived hydrologic characteristics in five areas in northern Alaska between the 1970s and 2000s. Change in total shrub cover ranged from − 0.65% to 46.56%. Change in floodplain shrub cover ranged from 3.38% to 76.22%. Shrubs are preferentially expanding into areas of higher topographic wetness index (TWI) values where the potential for moisture accumulation or drainage is greater. In addition, we found that floodplain shrub development was strongly associated with high TWI values and a decreasing average distance between shrubs and the river bank. This suggests an interacting influence of substrate removal and stabilization as a consequence of increased vegetation cover.

  4. Dynamic Analysis of Darrieus Vertical Axis Wind Turbine Rotors

    Science.gov (United States)

    Lobitz, D. W.

    1981-01-01

    The dynamic response characteristics of the vertical axis wind turbine (VAWT) rotor are important factors governing the safety and fatigue life of VAWT systems. The principal problems are the determination of critical rotor speeds (resonances) and the assessment of forced vibration response amplitudes. The solution to these problems is complicated by centrifugal and Coriolis effects which can have substantial influence on rotor resonant frequencies and mode shapes. The primary tools now in use for rotor analysis are described and discussed. These tools include a lumped spring mass model (VAWTDYN) and also finite-element based approaches. The accuracy and completeness of current capabilities are also discussed.

  5. Research on dynamic characteristics of new chaotic-advection fins

    International Nuclear Information System (INIS)

    Kong Songtao; Dong Qiwu; Liu Minshan; Zhu Qing

    2007-01-01

    Analysis and the numerical simulation has confirmed that the flow is of the chaotic advection in the flow channel of the new fin. The chaotic advection results in stronger mixing under low Re, and thus enhances the heat transfer and anti-scaling ability. The new fin provides the beneficial exploration to the concept of chaotic advection which applies to the plate-fin heat exchanger. (authors)

  6. Analysis of hydraulic characteristics for stream diversion in small stream

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sang-Jin; Jun, Kye-Won [Chungbuk National University, Cheongju(Korea)

    2001-10-31

    This study is the analysis of hydraulic characteristics for stream diversion reach by numerical model test. Through it we can provide the basis data in flood, and in grasping stream flow characteristics. Analysis of hydraulic characteristics in Seoknam stream were implemented by using computer model HEC-RAS(one-dimensional model) and RMA2(two-dimensional finite element model). As a result we became to know that RMA2 to simulate left, main channel, right in stream is more effective method in analysing flow in channel bends, steep slope, complex bed form effect stream flow characteristics, than HEC-RAS. (author). 13 refs., 3 tabs., 5 figs.

  7. Dynamic modeling and dynamical analysis of pump-turbines in S-shaped regions during runaway operation

    International Nuclear Information System (INIS)

    Zhang, Hao; Chen, Diyi; Wu, Changzhi; Wang, Xiangyu; Lee, Jae-Myung; Jung, Kwang-Hyo

    2017-01-01

    Highlights: • Novel dynamic model of a pump-turbine in S-shaped regions is proposed. • A stability criterion of runaway point is given. • Global dynamic characteristics of the pump-turbine are investigated. • Effects of the slopes of the characteristic curve on the stability are studied. - Abstract: There is a region of pump-turbine operation, often called the S-shaped region, in which one unit rotational speed corresponds to three unit flows or torques. In this paper, the dynamic model of the pump-turbine in S-shaped regions is established by introducing the nonlinear piecewise function of relative parameters. Then, the global bifurcation diagrams of the pump-turbine are presented to analyze its dynamic characteristics in the S-shaped regions. Meanwhile, a stability criterion of runaway point is given based on the established theoretical model. The numerical experiments are conducted on the model and the results are in good agreement with the theoretical analysis. Furthermore, the effects of the characteristic curve slopes on the stability of the pump-turbine are studied by an innovative use of the three-dimensional bifurcation diagrams. Finally, the factors influencing the runaway stability of pump-turbines are also discussed, based on the dynamic analysis.

  8. Nonlinear dynamic mechanism of vocal tremor from voice analysis and model simulations

    Science.gov (United States)

    Zhang, Yu; Jiang, Jack J.

    2008-09-01

    Nonlinear dynamic analysis and model simulations are used to study the nonlinear dynamic characteristics of vocal folds with vocal tremor, which can typically be characterized by low-frequency modulation and aperiodicity. Tremor voices from patients with disorders such as paresis, Parkinson's disease, hyperfunction, and adductor spasmodic dysphonia show low-dimensional characteristics, differing from random noise. Correlation dimension analysis statistically distinguishes tremor voices from normal voices. Furthermore, a nonlinear tremor model is proposed to study the vibrations of the vocal folds with vocal tremor. Fractal dimensions and positive Lyapunov exponents demonstrate the evidence of chaos in the tremor model, where amplitude and frequency play important roles in governing vocal fold dynamics. Nonlinear dynamic voice analysis and vocal fold modeling may provide a useful set of tools for understanding the dynamic mechanism of vocal tremor in patients with laryngeal diseases.

  9. The structural and dynamic characteristics of a water-polimer high-speed jet

    Directory of Open Access Journals (Sweden)

    Андрій Володимирович Погребняк

    2017-07-01

    Full Text Available The aim is to study the structural and dynamic characteristics of the water-polymer jet, what is of decisive importance for understanding the nature of the abnormally high cutting ability. A complex study of the structure and dynamics of a water-polymer high-speed jet has been carried out. Analysis of the photographs of jets of aqueous PEO solution indicates that adding polyethylene oxide (PEO into water results in a significant increase in the initial sections of the water-polymer jet, which characterizes the quality of its formation, and leads to compactness due to a reduction of its diameter. The obtained experimental data made it possible to propose a relationship for determining the dimensionless value of the initial sections of jets of aqueous PEO solutions of different concentration and molecular mass of PEO, taking into account the real parameters of the jet forming head. Investigation of changes in the energy capabilities of water-polymer jets, which were estimated by the force of the jet impact on the steel obstacle, made it possible to establish the features of their dynamics. The obtained experimental data explain the nature of the change in the cutting properties of the water-polymer jet as a function of the distance between the surface of the material that is being cut and the cut of the nozzle. If the distance from the nozzle to the surface of the material is less than the size of the initial sections of the water-polymer jet, an increase in the diameter of the nozzle outlet hole will lead to a reduction in the depth of the cut. If, however, the distance from the nozzle to the surface of the material approaches or exceeds the size of the main part of the water-polymer jet, then the depth of the cut will increase with increasing diameter of the nozzle at a constant pressure. The use of structural and dynamic characteristics of water-polymer jets is substantiated when establishing rational parameters of equipment for water

  10. Elastic-plastic dynamic analysis of a reactor building

    International Nuclear Information System (INIS)

    Umemura, Hajime; Tanaka, Hiroshi.

    1976-01-01

    The basic characteristics of the dynamic response of a reactor building to severe earthquake ground motion are very important for the evaluation of the safety of nuclear plant systems. A computer program for elastic-plastic dynamic analysis of reactor buildings using lumped mass models is developed. The box and cylindrical walls of boiling water reactor buildings are treated as vertical beams. The nonlinear moment-rotation and shear force-shear deformation relationships of walls are based in part upon the experiments of prototype structures. The geometrical non-linearity of the soil rocking spring due to foundation separation is also considered. The nonlinear equation of motion is expressed in incremental form using tangent stiffness matrices, following the algorithm developed by E.L. Wilson et al. The damping matrix in the equation is formulated as the combination of the energy evaluation method and Penzien-Wilson's approach to accomodate the different characteristics of soil and building damping. The analysis examples and the comparison of elastic and elastic-plastic analysis results are presented. (auth.)

  11. Dynamic Analysis of Tele-manipulator

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Min Sig; Lee, Seung Hyun; Kim, Doo Ho; Choi, Sun Il [Kyungwon Univ., Sungnam (Korea, Republic of)

    2008-03-15

    The manipulator can move linearly along X and Y-axes and has 6-degree rotational freedom. All deriving electric motors are mounted on the base platform to reduce inertia of links and tendons are used to transmit torque from the motors to the corresponding joints. In this report, a dynamic analysis of the manipulator has been carried out. Based on the dimensions of the designed links and allowable maximum rotational constraints on all joints, the maximum torque has been analyzed and working volume has been derived graphically through a numerical analysis. The Danavit-Hartenverg coordinate has been used through out this report. An inverse kinematic model which includes 3-linear and 3-rotational motions of the end effector and its numerical simulation program have been developed. The simulation results showed its validity and usefulness. The program are written in Symbolic Math provided by MatLab. A dynamic model which consists of rigid link dynamic models , driving motors and tendons which are used to tranmit the torques between motors and the corresponding joints. A simulation model written in Simmechanics has been derived and its validity and its usefulness were verified along with some simulation results.

  12. Integrated framework for dynamic safety analysis

    International Nuclear Information System (INIS)

    Kim, Tae Wan; Karanki, Durga R.

    2012-01-01

    In the conventional PSA (Probabilistic Safety Assessment), detailed plant simulations by independent thermal hydraulic (TH) codes are used in the development of accident sequence models. Typical accidents in a NPP involve complex interactions among process, safety systems, and operator actions. As independent TH codes do not have the models of operator actions and full safety systems, they cannot literally simulate the integrated and dynamic interactions of process, safety systems, and operator responses. Offline simulation with pre decided states and time delays may not model the accident sequences properly. Moreover, when stochastic variability in responses of accident models is considered, defining all the combinations for simulations will be cumbersome task. To overcome some of these limitations of conventional safety analysis approach, TH models are coupled with the stochastic models in the dynamic event tree (DET) framework, which provides flexibility to model the integrated response due to better communication as all the accident elements are in the same model. The advantages of this framework also include: Realistic modeling in dynamic scenarios, comprehensive results, integrated approach (both deterministic and probabilistic models), and support for HRA (Human Reliability Analysis)

  13. Dynamic Analysis of Tele-manipulator

    International Nuclear Information System (INIS)

    Kang, Min Sig; Lee, Seung Hyun; Kim, Doo Ho; Choi, Sun Il

    2008-03-01

    The manipulator can move linearly along X and Y-axes and has 6-degree rotational freedom. All deriving electric motors are mounted on the base platform to reduce inertia of links and tendons are used to transmit torque from the motors to the corresponding joints. In this report, a dynamic analysis of the manipulator has been carried out. Based on the dimensions of the designed links and allowable maximum rotational constraints on all joints, the maximum torque has been analyzed and working volume has been derived graphically through a numerical analysis. The Danavit-Hartenverg coordinate has been used through out this report. An inverse kinematic model which includes 3-linear and 3-rotational motions of the end effector and its numerical simulation program have been developed. The simulation results showed its validity and usefulness. The program are written in Symbolic Math provided by MatLab. A dynamic model which consists of rigid link dynamic models , driving motors and tendons which are used to tranmit the torques between motors and the corresponding joints. A simulation model written in Simmechanics has been derived and its validity and its usefulness were verified along with some simulation results

  14. Effect of Static-Dynamic Coupling Loading on Fracture Toughness and Failure Characteristics in Marble

    Directory of Open Access Journals (Sweden)

    Z. Q. Yin

    2014-03-01

    Full Text Available Fracture experiments in a notched semi-circular bend configuration were conducted to test the dynamic fracture toughness of a marble under static-dynamic coupling load using a modified split Hopkinson pressure bar. The fracture process of the specimen was monitored using a high speed (HS camera. Based on digital image correlation (DIC and strain gauges, the full-field strain fields and time-to-fracture of the marble were measured under static-dynamic coupling load. Experimental results show that dynamic fracture toughness was well determined, and the HS-DIC technique provides reliable full-field strain fields in the specimens under static-dynamic coupling loads. The failure characteristics of the marble under external impact were affected obviously by pre-compression stress. Increase of axial pre-compression stress was helpful to improve the crack propagation velocity, and dynamic crack initiation toughness was decreased.

  15. Dismissing Attachment Characteristics Dynamically Modulate Brain Networks Subserving Social Aversion.

    Science.gov (United States)

    Krause, Anna Linda; Borchardt, Viola; Li, Meng; van Tol, Marie-José; Demenescu, Liliana Ramona; Strauss, Bernhard; Kirchmann, Helmut; Buchheim, Anna; Metzger, Coraline D; Nolte, Tobias; Walter, Martin

    2016-01-01

    direct prediction of neuronal responses by individual attachment and trauma characteristics and reversely prediction of subjective experience by intrinsic functional connections. We consider these findings of activation of within-network and between-network connectivity modulated by inter-individual differences as substantial for the understanding of interpersonal processes, particularly in clinical settings.

  16. Dismissing attachment characteristics dynamically modulate brain networks subserving social aversion.

    Directory of Open Access Journals (Sweden)

    Anna Linda eKrause

    2016-03-01

    prediction of neuronal responses by individual attachment and trauma characteristics and reversely prediction of subjective experience by intrinsic functional connections. We consider these findings of activation of within-network and between-network connectivity modulated by inter-individual differences as substantial for the understanding of interpersonal processes, particularly in clinical settings.

  17. Nonlinear analysis and characteristics of inductive galloping energy harvesters

    Science.gov (United States)

    Dai, H. L.; Yang, Y. W.; Abdelkefi, A.; Wang, L.

    2018-06-01

    This paper presents an investigation on analysis and characteristics of aerodynamic electromagnetic energy harvesters. The source of aeroelastic oscillations results from galloping of a prismatic structure. A nonlinear distributed-parameter model is developed representing the dynamics of the transverse degree of freedom and the electric current induced in the coil. Firstly, we perform a linear analysis to study the impacts of the external electrical resistance, magnet placement, electromagnetic coupling coefficient, and internal resistance in the coil on the cut-in speed of instability of the coupled electroaeroelastic system. It is demonstrated that these parameters have significant impacts on cut-in speed of instability of the harvester system. Subsequently, a nonlinear analysis is implemented to explore the influences of these parameters on the output property of the energy harvester. The results show that there exists an optimal external electrical resistance which maximizes the output power of the harvester, and this optimal value varies with the magnet's placement, wind speed, electromagnetic coupling coefficient and internal resistance of the coil. It is also demonstrated that an increase in the distance between the clamped end and the magnet, an increase in the electromagnetic coupling coefficient, and/or a decrease in the internal resistance of the coil are accompanied by an increase in the level of the harvested power and a decrease in the tip displacement of the bluff body which is associated with a resistive-shunt damping effect in the harvester. The implemented studies give a constructive guidance to design and enhance the output performance of aerodynamic electromagnetic energy harvesters.

  18. Prediction of dynamic and aerodynamic characteristics of the centrifugal fan with forward curved blades

    Science.gov (United States)

    Polanský, Jiří; Kalmár, László; Gášpár, Roman

    2013-12-01

    The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic "A" variant contains 12 blades. The geometry of second "B" variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant "C" contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.

  19. Static and Dynamic Characteristics of a Long-Span Cable-Stayed Bridge with CFRP Cables

    Directory of Open Access Journals (Sweden)

    Xu Xie

    2014-06-01

    Full Text Available In this study, the scope of CFRP cables in cable-stayed bridges is studied by establishing a numerical model of a 1400-m span of the same. The mechanical properties and characteristics of CFRP stay cables and of a cable-stayed bridge with CFRP cables are here subjected to comprehensive analysis. The anomalies in the damping properties of free vibration, nonlinear parametric vibration and wind fluctuating vibration between steel cables and CFRP cables are determined. The structural stiffness, wind resistance and traffic vibration of the cable-stayed bridge with CFRP cables are also analyzed. It was found that the static performances of a cable-stayed bridge with CFRP cables and steel cables are basically the same. The natural frequencies of CFRP cables do not coincide with the major natural frequencies of the cable-stayed bridge, so the likelihood of CFRP cable-bridge coupling vibration is minuscule. For CFRP cables, the response amplitudes of both parametric vibration and wind fluctuating vibration are smaller than those of steel cables. It can be concluded from the research that the use of CFRP cables does not change the dynamic characteristics of the vehicle-bridge coupling vibration. Therefore, they can be used in long-span cable-stayed bridges with an excellent mechanical performance.

  20. Static and Dynamic Characteristics of a Long-Span Cable-Stayed Bridge with CFRP Cables.

    Science.gov (United States)

    Xie, Xu; Li, Xiaozhang; Shen, Yonggang

    2014-06-23

    In this study, the scope of CFRP cables in cable-stayed bridges is studied by establishing a numerical model of a 1400-m span of the same. The mechanical properties and characteristics of CFRP stay cables and of a cable-stayed bridge with CFRP cables are here subjected to comprehensive analysis. The anomalies in the damping properties of free vibration, nonlinear parametric vibration and wind fluctuating vibration between steel cables and CFRP cables are determined. The structural stiffness, wind resistance and traffic vibration of the cable-stayed bridge with CFRP cables are also analyzed. It was found that the static performances of a cable-stayed bridge with CFRP cables and steel cables are basically the same. The natural frequencies of CFRP cables do not coincide with the major natural frequencies of the cable-stayed bridge, so the likelihood of CFRP cable-bridge coupling vibration is minuscule. For CFRP cables, the response amplitudes of both parametric vibration and wind fluctuating vibration are smaller than those of steel cables. It can be concluded from the research that the use of CFRP cables does not change the dynamic characteristics of the vehicle-bridge coupling vibration. Therefore, they can be used in long-span cable-stayed bridges with an excellent mechanical performance.

  1. Cooling Characteristic Analysis of Transformer's Radiator

    International Nuclear Information System (INIS)

    Kim, Hyun Jae; Yang, Si Won; Kim, Won Seok; Kweon, Ki Yeoung; Lee, Min Jea

    2007-01-01

    A transformer is a device that changes the current and voltage by electricity induced between coil and core steel, and it is composed of metals and insulating materials. In the core of the transformer, the thermal load is generated by electric loss and the high temperature can make the break of insulating. So we must cool down the temperature of transformer by external radiators. According to cooling fan's usage, there are two cooling types, OA(Oil Natural Air Natural) and FA(Oil Natural Air Forced). For this study , we used Fluent 6.2 and analyzed the cooling characteristic of radiator. we calculated 1-fin of detail modeling that is similar to honeycomb structure and multi-fin(18-fin) calculation for OA and FA types. For the sensitivity study, we have different positions(side, under) of cooling fans for forced convection of FA type. The calculation results were compared with the measurement data which obtained from 135.45/69kV ultra transformer flowrate and temperature test. The aim of the study is to assess the Fluent code prediction on the radiator calculation and to use the data for optimizing transformer radiator design

  2. Analysis of static and dynamic pile-soil-jacket behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Azadi, Mohammad Reza Emami

    1998-12-31

    In the offshore industry, recent extreme storms, severe earthquakes and subsidence of the foundation of jacket platforms have shown that new models and methods must take into account the jacket- pile-soil foundation interaction as well as the non-linear dynamic performance/loading effects. This thesis begins with a review of the state of art pile-soil interaction model, recognizing that most existing pile-soil models have been established based on large diameter pile tests on specific sites. The need for site independent and mechanistic pile-soil interaction models led to the development of new (t-z) and (p-y) disk models. These are validated using the available database from recent large diameter pile tests in the North Sea and Gulf of Mexico. The established static disk models are applied for non-linear static analysis of the jacket-pile-soil system under extreme wave loading. Dynamic pile-soil interaction is studied and a new disk-cone model is developed for the non-linear and non-homogeneous soils. This model is applied to both surface and embedded disks in a soil layer with non-linear properties. Simplified non-linear as well as more complex analysis methods are used to study the dynamic response of the jacket platform under extreme sea and seismic loading. Ductility spectra analysis is introduced and used to study the dynamic performance of the jacket systems near collapse. Case studies are used to illustrate the effects of structural, foundation failure characteristics as well as dynamic loading effects on the overall performance of the jacket-pile-soil systems near ultimate collapse. 175 refs., 429 figs., 70 tabs.

  3. Design and analysis of diaphragms in dynamic microphones

    Directory of Open Access Journals (Sweden)

    Zi-Gui Huang

    2015-07-01

    Full Text Available Most contemporary high-end microphones are dynamic microphones, adopting the most basic electromagnetic transduction principles. This study investigated the diaphragm structures of dynamic microphones. The diaphragms were composed of polyimide material, and the boundary settings required for actual operation were provided using finite element model analysis software. The characteristic frequencies caused by grooving variations on the three-dimensional diaphragm were analyzed for the various groove shapes and number. The groove angles and width variations were examined based on the optimal groove shape selected in the aforementioned analysis, and the effects of these shapes were determined based on the analytical results. Acoustic waves cause thin films to vibrate, forming the working principle behind dynamic microphones. The thin film drives a coil to vibrate in a magnetic field and cuts the line of magnetic force, subsequently producing a voltage on both ends of the coil. This audio-frequency-inducted voltage represents an acoustic wave message. The finite element model analysis software was used to conduct electromagnetic induction simulations; the sound source was fed to the diaphragm to drive the coil. The coil vibrations caused the line of magnetic force to be cut, and the final voltages produced were examined and compared.

  4. Characteristic analysis and experiment of pneumatic servo valve

    International Nuclear Information System (INIS)

    Kim, Dong Soo; Lee, Won Hee; Choi, Byung Oh

    2004-01-01

    Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The first objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. And a tester for conducting an overall performance test was designed and manufactured, and as a result of conducting the flow rate test, the pressure test and the frequency test on the developed pneumatic servo valve

  5. Research progress of the static and dynamic characteristics and motion errors of hydrostatic supports

    Directory of Open Access Journals (Sweden)

    Zhiwei WANG

    2016-06-01

    Full Text Available At present, the research on static and dynamic characteristics of hydrostatic supports depend on the form and structure of the restrictor, which are mainly focused on the influences of recess shape, bearing structure, bearing surface roughness, lubricant and elastic deformations of the bearing. There are few studies on the thermal effect of hydrostatic supports and static and dynamic characteristics of hydrostatic guideways. The research on motion errors of hydrostatic supports is primarily based on the static equilibrium of the moving part. The effects of the motion speed of the moving part and structural deformation on the motion errors are not considered. Finally, the research prospects from the standardization, modularization and industrialization of hydrostatic supports, thermal effect of hydrostatic bearing, the static and dynamic characteristics of hydrostatic guideways and motion errors of hydrostatic supports under operating conditions are concluded.

  6. Effect of Stiffness of Rolling Joints on the Dynamic Characteristic of Ball Screw Feed Systems in a Milling Machine

    Directory of Open Access Journals (Sweden)

    Dazhong Wang

    2015-01-01

    Full Text Available Dynamic characteristic of ball screw feed system in a milling machine is studied numerically in this work. In order to avoid the difficulty in determining the stiffness of rolling joints theoretically, a dynamic modeling method for analyzing the feed system is discussed, and a stiffness calculation method of the rolling joints is proposed based on the Hertz contact theory. Taking a 3-axis computer numerical control (CNC milling machine set ermined as a research object, the stiffness of its fixed joint between the column and the body together with the stiffness parameters of the rolling joints is evaluated according to the Takashi Yoshimura method. Then, a finite element (FE model is established for the machine tool. The correctness of the FE model and the stiffness calculation method of the rolling joints are validated by theoretical and experimental modal analysis results of the machine tool’s workbench. Under the two modeling methods of joints incorporating the stiffness parameters and rigid connection, a theoretical modal analysis is conducted for the CNC milling machine. The natural frequencies and modal shapes reveal that the joints’ dynamic characteristic has an important influence on the dynamic performance of a whole machine tool, especially for the case with natural frequency and higher modes.

  7. Experimental test of static and dynamic characteristics of tilting-pad thrust bearings

    OpenAIRE

    Annan Guo; Xiaojing Wang; Jian Jin; Diann Y Hua; Zikai Hua

    2015-01-01

    The axial vibration in turbine machine has attracted more and more interest. Tilting-pad thrust bearings are widely used in turbine machines to support the axial load. The dynamic properties generated by oil film of the thrust pad have important effects on the axial vibration of the rotor-bearing system. It is necessary to develop the method to test the dynamic characteristics of thrust bearings. A new rig has been developed. The facility allows a complete set of bearing operating parameters ...

  8. Analysis of characteristic performance curves in radiodiagnosis by an observer

    International Nuclear Information System (INIS)

    Kossovoj, A.L.

    1988-01-01

    Methods and ways of construction of performance characteristic curves (PX-curves) in roentgenology, their qualitative and quantitative estimation are described. Estimation of PX curves application for analysis of scintigraphic and sonographic images is presented

  9. Experimental test of static and dynamic characteristics of tilting-pad thrust bearings

    Directory of Open Access Journals (Sweden)

    Annan Guo

    2015-07-01

    Full Text Available The axial vibration in turbine machine has attracted more and more interest. Tilting-pad thrust bearings are widely used in turbine machines to support the axial load. The dynamic properties generated by oil film of the thrust pad have important effects on the axial vibration of the rotor-bearing system. It is necessary to develop the method to test the dynamic characteristics of thrust bearings. A new rig has been developed. The facility allows a complete set of bearing operating parameters to be measured. Parameters measured include oil temperatures, oil-film thickness, and pressure. The static load and dynamic load can be added on the thrust bearing in the vertical direction at the same time. The relative and absolute displacement vibrations of the test experimental bearing with the changes of dynamic force are measured, and the dynamic characteristics of the test bearing are obtained. The experimental results show clearly that the operating conditions influence largely on the pad static and dynamic characteristics.

  10. Architectural Analysis of Dynamically Reconfigurable Systems

    Science.gov (United States)

    Lindvall, Mikael; Godfrey, Sally; Ackermann, Chris; Ray, Arnab; Yonkwa, Lyly

    2010-01-01

    oTpics include: the problem (increased flexibility of architectural styles decrease analyzability, behavior emerges and varies depending on the configuration, does the resulting system run according to the intended design, and architectural decisions can impede or facilitate testing); top down approach to architecture analysis, detection of defects and deviations, and architecture and its testability; currently targeted projects GMSEC and CFS; analyzing software architectures; analyzing runtime events; actual architecture recognition; GMPUB in Dynamic SAVE; sample output from new approach; taking message timing delays into account; CFS examples of architecture and testability; some recommendations for improved testablity; and CFS examples of abstract interfaces and testability; CFS example of opening some internal details.

  11. Dynamic Analysis and Test Results for an STC Stirling Generator

    Science.gov (United States)

    Qiu, Songgang; Peterson, Allen A.

    2004-02-01

    Long-life, high-efficiency generators based on free-piston Stirling machines are a future energy-conversion solution for both space and commercial applications. To aid in design and system integration efforts, Stirling Technology Company (STC) has developed dynamic simulation models for the internal moving subassemblies and for complete Stirling convertor assemblies. These dynamic models have been validated using test data from operating prototypes. Simplified versions of these models are presented to help explain the operating characteristics of the Stirling convertor. Power spectrum analysis is presented for the test data for casing acceleration, piston motion, displacer motion, and controller current/voltage during full power operation. The harmonics of a Stirling convertor and its moving components are identified for the STC zener-diode control scheme. The dynamic behavior of each moving component and its contribution to the system dynamics and resultant vibration forces are discussed. Additionally, the effects of a passive balancer and external suspension are predicted by another simplified system model.

  12. Perturbation analysis for patch occupancy dynamics

    Science.gov (United States)

    Martin, Julien; Nichols, James D.; McIntyre, Carol L.; Ferraz, Goncalo; Hines, James E.

    2009-01-01

    Perturbation analysis is a powerful tool to study population and community dynamics. This article describes expressions for sensitivity metrics reflecting changes in equilibrium occupancy resulting from small changes in the vital rates of patch occupancy dynamics (i.e., probabilities of local patch colonization and extinction). We illustrate our approach with a case study of occupancy dynamics of Golden Eagle (Aquila chrysaetos) nesting territories. Examination of the hypothesis of system equilibrium suggests that the system satisfies equilibrium conditions. Estimates of vital rates obtained using patch occupancy models are used to estimate equilibrium patch occupancy of eagles. We then compute estimates of sensitivity metrics and discuss their implications for eagle population ecology and management. Finally, we discuss the intuition underlying our sensitivity metrics and then provide examples of ecological questions that can be addressed using perturbation analyses. For instance, the sensitivity metrics lead to predictions about the relative importance of local colonization and local extinction probabilities in influencing equilibrium occupancy for rare and common species.

  13. Sensitivity analysis of reactive ecological dynamics.

    Science.gov (United States)

    Verdy, Ariane; Caswell, Hal

    2008-08-01

    Ecological systems with asymptotically stable equilibria may exhibit significant transient dynamics following perturbations. In some cases, these transient dynamics include the possibility of excursions away from the equilibrium before the eventual return; systems that exhibit such amplification of perturbations are called reactive. Reactivity is a common property of ecological systems, and the amplification can be large and long-lasting. The transient response of a reactive ecosystem depends on the parameters of the underlying model. To investigate this dependence, we develop sensitivity analyses for indices of transient dynamics (reactivity, the amplification envelope, and the optimal perturbation) in both continuous- and discrete-time models written in matrix form. The sensitivity calculations require expressions, some of them new, for the derivatives of equilibria, eigenvalues, singular values, and singular vectors, obtained using matrix calculus. Sensitivity analysis provides a quantitative framework for investigating the mechanisms leading to transient growth. We apply the methodology to a predator-prey model and a size-structured food web model. The results suggest predator-driven and prey-driven mechanisms for transient amplification resulting from multispecies interactions.

  14. The Subject Analysis of Payment Systems Characteristics

    Directory of Open Access Journals (Sweden)

    Korobeynikova Olga Mikhaylovna

    2015-09-01

    Full Text Available The article deals with the analysis of payment systems aimed at identifying the categorical terminological apparatus, proving their specific features and revealing the impact of payment systems on the state of money turnover. On the basis of the subject analysis, the author formulates the definitions of a payment system (characterized by increasing speed of effecting payments, by the reduction of costs, by high degree of payments convenience for subjects of transactions, by security of payments, by acceptable level of risks and by social efficiency, a national payment system, and a local payment system (characterized by the growth of economic and social efficiency of systems participants, by the process of money turnover optimization on the basis of saving transaction costs and increasing speed of money flows within the local payment systems. According to the economic levels, the payment systems are divided to macrosystems (national payment systems, mezosystems (payment systems localized on the operational and territorial basis, microsystems (payments by individual economic subjects. The establishment of qualitative features of payment systems, which is a basis of the author’s terminological interpretation, gave a possibility to reveal the cause-effect relations of payment systems influence on the state of money turnover in the involved subjects, and on the economy as a whole. The result of the present research consists in revealing the payment systems influence on the state of money turnover which is significant: at the state and regional level – in the optimization of budget and inter-budgetary relations, in acceleration of the money turnover, in deceleration of the money supply and inflation rate, in reduced need in money emission; at the level of economic entities – in accelerating the money turnover and accounts receivable, in the reduction of debit and credit loans, in the growth of profit (turnover; at the household level – in

  15. Characterization of Enhancing MS Lesions by Dynamic Texture Parameter Analysis of Dynamic Susceptibility Perfusion Imaging

    Directory of Open Access Journals (Sweden)

    Rajeev K. Verma

    2016-01-01

    Full Text Available Purpose. The purpose of this study was to investigate statistical differences with MR perfusion imaging features that reflect the dynamics of Gadolinium-uptake in MS lesions using dynamic texture parameter analysis (DTPA. Methods. We investigated 51 MS lesions (25 enhancing, 26 nonenhancing lesions of 12 patients. Enhancing lesions (n=25 were prestratified into enhancing lesions with increased permeability (EL+; n=11 and enhancing lesions with subtle permeability (EL−; n=14. Histogram-based feature maps were computed from the raw DSC-image time series and the corresponding texture parameters were analyzed during the inflow, outflow, and reperfusion time intervals. Results. Significant differences (p<0.05 were found between EL+ and EL− and between EL+ and nonenhancing inactive lesions (NEL. Main effects between EL+ versus EL− and EL+ versus NEL were observed during reperfusion (mainly in mean and standard deviation (SD: EL+ versus EL− and EL+ versus NEL, while EL− and NEL differed only in their SD during outflow. Conclusion. DTPA allows grading enhancing MS lesions according to their perfusion characteristics. Texture parameters of EL− were similar to NEL, while EL+ differed significantly from EL− and NEL. Dynamic texture analysis may thus be further investigated as noninvasive endogenous marker of lesion formation and restoration.

  16. Effect of Magnetohydrodynamic Couple Stresses on Dynamic Characteristics of Exponential Slider Bearing

    Directory of Open Access Journals (Sweden)

    N.B. Naduvinamani

    2017-05-01

    Full Text Available The effect of couple stresses on static and dynamic characteristics of exponential slider bearing in the presence of magnetic field considering squeeze action is theoretically analyzed in this paper. The modified magnetohydrodynamic couple stress Reynolds type equation is derived on the basis of Stokes couple stress model and closed form expressions are obtained for static and dynamic character coefficients. Comparing with bearing lubricated with non-conducting Newtonian lubricants, the magnetohydrodynamic couple stress lubrication provides the higher steady load carrying capacity, dynamic stiffness and damping coefficient. The exponential bearing shows higher efficiency for small film thickness at higher value of couple stress parameter and Hartmann number.

  17. Analysis of pile foundations under dynamic loads

    International Nuclear Information System (INIS)

    Waas, G.; Hartmann, H.G.

    1981-01-01

    A method is presented for the analysis of pile foundations which are subjected to horizontal dynamic loads from earthquakes, airplane impact, gas explosion or other sources. The motion of the pile cap and the pile forces are computed. - The loads may be applied to the pile cap or directly to the piles (e.g. by earthquake wave motion). The soil may be stratified and is considered to be an elastic or visco-elastic medium. The piles are assumed vertical. The method makes use of an approximate fundamental solution for displacements caused by a dynamic point load in a layered visco-elastic medium. The approximation involves a discretization of the medium in the vertical direction. In horizontal directions the medium is treated by continuum theory. The soil medium supports each pile at about 10 to 20 nodes. A dynamic flexiblity matrix for the soil is derived which relates the elastic, damping and inertial forces of the soil to the displacements at each node. It includes effects of radiation damping. All piles are coupled through the soil flexibility matrix. The piles are modelled by beam elements. Transient response is computed using fast discrete Fourier transforms. The arrangement of the piles is arbitrary. However, simple and double symmetry can be accounted for by the computer program. When the pile arrangement is axisymmetric, the degrees of freedom can be reduced to only those of two piles per ring. The influence of the number of piles and the influence of the pile spacing on group stiffness and on pile forces is presented for two soil profiles. Dynamic effects on pile forces of a foundation for a reactor building are studied. They are significant when soils are soft. (orig.)

  18. Dynamic Performance Characteristic Tests of Real Scale Lead Rubber Bearing for the Evaluation of Performance Criteria

    International Nuclear Information System (INIS)

    Kim, Min Kyu; Kim, Jung-Han; Choi, In-Kil

    2014-01-01

    Dynamic characteristic tests of full scale lead rubber bearing were performed for the evaluation of performance criteria of isolation system for nuclear power plants. For the dynamic test for a full scale rubber bearing, two 1500mm diameter lead rubber bearings were manufactured. The viewpoints of this dynamic test are determination of an ultimate shear strain level of lead rubber bearing, behavior of rubber bearing according to static and dynamic input motion, sinusoidal and random (earthquake) motion, and 1-dimentional and 2-dimensional input motion. In this study, seismic isolation device tests were performed for the evaluation of performance criteria of isolation system. Through this test, it can be recognized that in the case of considering a mechanical property test, dynamic and multi degree of loading conditions should be determined. But these differences should be examined how much affect to the global structural behavior

  19. In Situ Test Study of Characteristics of Coal Mining Dynamic Load

    Directory of Open Access Journals (Sweden)

    Jiang He

    2015-01-01

    Full Text Available Combination of coal mining dynamic load and high static stress can easily induce such dynamic disasters as rock burst, coal and gas outburst, roof fall, and water inrush. In order to obtain the characteristic parameters of mining dynamic load and dynamic mechanism of coal and rock, the stress wave theory is applied to derive the relation of mining dynamic load strain rate and stress wave parameters. The in situ test was applied to study the stress wave propagation law of coal mine dynamic load by using the SOS microseismic monitoring system. An evaluation method for mining dynamic load strain rate was proposed, and the statistical evaluation was carried out for the range of strain rate. The research results show that the loading strain rate of mining dynamic load is in direct proportion to the seismic frequency of coal-rock mass and particle peak vibration velocity and is in inverse proportion to wave velocity. The high-frequency component damps faster than the low-frequency component in the shockwave propagating process; and the peak particle vibration velocity has a power functional relationship with the transmitting distance. The loading strain rate of mining dynamic load is generally less than class 10−1/s.

  20. Understanding Team Communication Characteristics using Social Network Analysis

    International Nuclear Information System (INIS)

    Kim, Ar Ryum; Lee, Seung Woo; Seong, Poong Hyun; Park, Jin Kyun

    2011-01-01

    An important aspect of human behavior in nuclear power plants (NPPs) is team interaction since operating NPPs involves the coordination of several team members among and within workplaces. Since operators in main control room (MCR) get a great deal of information through communication to perform a task, communication is one of the important characteristics for team characteristics. Many researchers have been studying how to understand the characteristics of communication. Social network analysis (SNA) which is considered as an objective and easily applicable method has been already applied in many fields to investigate characteristics of team communication. Henttonen (2010) has struggled to perform the research on the impact of social networks in a team and he found some team communication characteristics could be obtained using some properties of SNA. In this paper, SNA is used to understand communication characteristics within operators in NPPs

  1. Dynamical system analysis of interacting models

    Science.gov (United States)

    Carneiro, S.; Borges, H. A.

    2018-01-01

    We perform a dynamical system analysis of a cosmological model with linear dependence between the vacuum density and the Hubble parameter, with constant-rate creation of dark matter. We show that the de Sitter spacetime is an asymptotically stable critical point, future limit of any expanding solution. Our analysis also shows that the Minkowski spacetime is an unstable critical point, which eventually collapses to a singularity. In this way, such a prescription for the vacuum decay not only predicts the correct future de Sitter limit, but also forbids the existence of a stable Minkowski universe. We also study the effect of matter creation on the growth of structures and their peculiar velocities, showing that it is inside the current errors of redshift space distortions observations.

  2. Paradoxical response to an emotional task: Trait characteristics and heart-rate dynamics

    NARCIS (Netherlands)

    Balocchia, R.; Varanini, M.; Paoletti, G.; Mecacci, G.; Santarcangelo, E.L.

    2015-01-01

    The present study evaluated the heart-rate dynamics of subjects reporting decreased (responders) or paradoxically increased relaxation (nonresponders) at the end of a threatening movie. Heart-rate dynamics were characterized by indices extracted through recurrence quantification analysis (RQA) and

  3. Sediment characteristics and wind-induced sediment dynamics in shallow Lake Markermeer, the Netherlands

    NARCIS (Netherlands)

    Kelderman, P.; Ang'weya, R.O.; De Rozari, P.; Vijverberg, T.

    2012-01-01

    In 2007/08, a study was undertaken on the sediment dynamics in shallow Lake Markermeer (the Netherlands). Firstly, sediment characteristics were determined at 49 sites in the lake. Parameters such as median grain size and loss on ignition showed a spatial as well as water depth related pattern,

  4. Static and dynamic characteristics of an ethyl alcohol analyzer in a fermentation medium

    Energy Technology Data Exchange (ETDEWEB)

    Kadlec, K

    1980-01-01

    An analyzer for the indirect determination of EtOH in fermentation media is described, with particular reference to its static and dynamic characteristics, the effect of different variables and factors on accuracy, and the influence of sensor postioning on readings. General theoretical relations are derived and exemplified by actual laboratory application.

  5. Dynamic characteristics of hydrocarbon fuel within the channel at supercritical and pyrolysis condition

    Science.gov (United States)

    Yu, Bin; Zhou, Weixing; Qin, Jiang; Bao, Wen

    2017-12-01

    Regenerative cooling with fuel as the coolant is used in the scramjet engine. In order to grasp the dynamic characteristics of engine fuel supply processes, this article studies the dynamic characteristics of hydrocarbon fuel within the channel. A one-dimensional dynamic model was proved, the thermal energy storage effect, fuel volume effect and chemical dynamic effect have been considered in the model, the ordinary differential equations were solved using a 4th order Runge-Kutta method. The precision of the model was validated by three groups of experimental data. The effects of input signal, working condition, tube size on the dynamic characteristics of pressure, flow rate, temperature have been simulated. It is found that cracking reaction increased the compressibility of the fuel pyrolysis mixture and lead to longer responding time of outlet flow. The responding time of outlet flow can reach 3s when tube is 5m long which will greatly influence the control performance of the engine thrust system. Meanwhile, when the inlet flow rate appears the step change, the inlet pressure leads to overshoot, the overshoot can reach as much as 100%, such highly transient impulse will result in detrimental effect on fuel pump.

  6. Effects of Tightening Torque on Dynamic Characteristics of Low Pressure Rotors Connected by a Spline Coupling

    Institute of Scientific and Technical Information of China (English)

    Chen Xi; Liao M ingfu; Li Quankun

    2017-01-01

    A rotor dynamic model is built up for investigating the effects of tightening torque on dynamic character-istics of low pressure rotors connected by a spline coupling .The experimental rotor system is established using a fluted disk and a speed sensor which is applied in an actual aero engine for speed measurement .Through simulating calculation and experiments ,the effects of tightening torque on the dynamic characteristics of the rotor system con-nected by a spline coupling including critical speeds ,vibration modes and unbalance responses are analyzed .The results show that when increasing the tightening torque ,the first two critical speeds and the amplitudes of unbal-ance response gradually increase in varying degrees while the vibration modes are essentially unchanged .In addi-tion ,changing axial and circumferential positions of the mass unbalance can lead to various amplitudes of unbalance response and even the rates of change .

  7. Dynamic Characteristics of a New Machine for Fatigue Testing of Railway Axles – Part 2

    Directory of Open Access Journals (Sweden)

    Karel FRYDRÝŠEK

    2012-06-01

    Full Text Available There were done some proposal calculations for a new testing machine. This new testing machine is determined for a dynamic fatigue testing of railway axles. The railway axles are subjected to bending and rotation (centrifugal effects. For the right proposition of a new machine is very important to know the basic dynamic characteristics of whole system. These dynamic characteristics are solved via FEM (MSC.Marc/Mentat software in combination with SBRA (Simulation-Based Reliability Assessment Method (probabilistic Monte Carlo approach, Anthill and Python software. The proposed dimensions and springs of a new machine for fatigue testing of railway axles were used for manufacturing. Application of the SBRA method connected with FEM in these areas is a new and innovative trend in mechanics. This paper is continuation of former work (i.e. easier deterministic approach already presented in this journal in 2007.

  8. Dynamic rupture analysis of reinforced concrete shells

    International Nuclear Information System (INIS)

    Rebora, B.; Zimmermann, Th.; Wolf, J.P.

    1976-01-01

    Extreme dynamic loading conditions often require the rupture analysis of reinforced and prestressed-concrete structures. The study presented in this paper extends a method of analysis of dynamic loading conditions which has proven efficient for short-time loads. Another aim is to adapt the method to thin-walled structures. It is not sufficient to work only with plastic rupture and yield surfaces locally which are compared to the elastic distribution of the stress resultants; it is essential to account for the redistribution of the latter. The method proposed consists of discretizing the structure into isoparametric three-dimensional elements with 20 nodes for the concrete and one-dimensional bar elements with three nodes for the steel. The latter can also be handled with a 'smeared' two-dimensional membrane element. In compression a three-dimensional non-linear elastic constitutive law is introduced for the concrete, and a triaxial failure surface expressed in the stress invariants is used, determining cracking and crushing. Two- and three-dimensional cracking surfaces in which no components of stress are transmitted are accounted for. The possibility exists that, during the history of loading, cracks can close up again. For steel, a yield criterion is selected. The non-linear analysis is based on the concept of initial stress. Residual loads are calculated using information in Gauss integration points. The ultimate load is reached when the algorithm does not converge. The corresponding failure modes can be interpreted as those for which a state of equilibrium is no longer possible. The equations of motion are discretized in time, using an extension of the linear acceleration method. (Auth.)

  9. Design and characteristics of a scattering chamber for PIXE analysis

    International Nuclear Information System (INIS)

    Oliver, A.; Miranda, J.; Lopez, K.; Mercado, F.; Flores, A.H.

    1989-01-01

    A scattering chamber for Particle Induced x-ray Emission (PIXE) analysis is described. This chamber was designed and constructed for thin film thickness measurements and depth profiling. The chamber operation characteristics and versatility in materials analysis are shown. (Author). 18 refs, 6 figs

  10. Dynamic Equivalent Modeling of a Grid-Tied Microgrid Based on Characteristic Model and Measurement Data

    Directory of Open Access Journals (Sweden)

    Changchun Cai

    2017-11-01

    Full Text Available Microgrids can significantly improve the utilization of distributed generation (DG and the reliability of the power supply. However, in the grid-tied operational mode, the interaction between the microgrid and the distribution network cannot be ignored. The paper proposes an equivalent modeling method for the microgrid under grid-tied mode based on a characteristic model. It can simplify the microgrid model in the numerical simulation of the distribution network. The proposed equivalent model can present the dynamic response of a microgrid but not miss any of its primary characteristics. The characteristic model is represented by a low-order time-varying differential equation with the same characteristics of the original microgrid system. During the modeling process, the voltage and the power exchanged between the microgrid and distribution network are collected as the training data for the identification of model parameters. A recursive damped least squares algorithm (RDLS is used for the parameter identification. A microgrid system containing different DGs is built to test the proposed modeling method in DIgSILENT, and the results show that the proposed dynamic equivalent modeling method is effective and the characteristic model can present the dynamic behaviors of the detailed model of a microgrid.

  11. Constant Cutting Force Control for CNC Machining Using Dynamic Characteristic-Based Fuzzy Controller

    Directory of Open Access Journals (Sweden)

    Hengli Liu

    2015-01-01

    Full Text Available This paper presents a dynamic characteristic-based fuzzy adaptive control algorithm (DCbFACA to avoid the influence of cutting force changing rapidly on the machining stability and precision. The cutting force is indirectly obtained in real time by monitoring and extraction of the motorized spindle current, the feed speed is fuzzy adjusted online, and the current was used as a feedback to control cutting force and maintain the machining process stable. Different from the traditional fuzzy control methods using the experience-based control rules, and according to the complex nonlinear characteristics of CNC machining, the power bond graph method is implemented to describe the dynamic characteristics of process, and then the appropriate variation relations are achieved between current and feed speed, and the control rules are optimized and established based on it. The numerical results indicated that DCbFACA can make the CNC machining process more stable and improve the machining precision.

  12. Dynamic analysis of savings and economic growth in Nigeria ...

    African Journals Online (AJOL)

    Dynamic analysis of savings and economic growth in Nigeria. ... a trivariate dynamic Granger causality model with savings, economic growth and foreign ... It is recommended that in the short run, policies in Nigeria should be geared towards ...

  13. Incremental Dynamic Analysis of Koyna Dam under Repeated Ground Motions

    Science.gov (United States)

    Zainab Nik Azizan, Nik; Majid, Taksiah A.; Nazri, Fadzli Mohamed; Maity, Damodar; Abdullah, Junaidah

    2018-03-01

    This paper discovers the incremental dynamic analysis (IDA) of concrete gravity dam under single and repeated earthquake loadings to identify the limit state of the dam. Seven ground motions with horizontal and vertical direction as seismic input considered in the nonlinear dynamic analysis based on the real repeated earthquake in the worldwide. All the ground motions convert to respond spectrum and scaled according to the developed elastic respond spectrum in order to match the characteristic of the ground motion to the soil type. The scaled was depends on the fundamental period, T1 of the dam. The Koyna dam has been selected as a case study for the purpose of the analysis by assuming that no sliding and rigid foundation, has been estimated. IDA curves for Koyna dam developed for single and repeated ground motions and the performance level of the dam identifies. The IDA curve of repeated ground motion shown stiffer rather than single ground motion. The ultimate state displacement for a single event is 45.59mm and decreased to 39.33mm under repeated events which are decreased about 14%. This showed that the performance level of the dam based on seismic loadings depend on ground motion pattern.

  14. ON THE ANALYSIS OF IMPEDANCE-DRIVEN REVERSE FLOW DYNAMICS

    Directory of Open Access Journals (Sweden)

    LEE V. C.-C.

    2017-02-01

    Full Text Available Impedance pump is a simple valve-less pumping mechanism, where an elastic tube is joined to a more rigid tube, at both ends. By inducing a periodic asymmetrical compression on the elastic tube will produce a unidirectional flow within the system. This pumping concept offers a low energy, low noise alternative, which makes it an effective driving mechanism, especially for micro-fluidic systems. In addition, the wave-based mechanism through which pumping occurs infers many benefits in terms of simplicity of design and manufacturing. Adjustment of simple parameters such as the excitation frequencies or compression locations will reverse the direction of flow, providing a very versatile range of flow outputs. This paper describes the experimental analysis of such impedance-driven flow with emphasis on the dynamical study of the reverse flow in open-loop environment. In this study, tapered section with converging steps is introduced at both ends of the elastic tube to amplify the magnitude of reverse flow. Study conducted shows that the reverse peak flow is rather significant with estimate of 23% lower than the forward peak flow. The flow dynamics on the other hand has shown to exhibit different characteristics as per the forward peak flow. The flow characteristics is then studied and showed that the tapered sections altered the impedance within the system and hence induce a higher flow in the reverse direction.

  15. Dynamic analysis of the BPX machine structure

    International Nuclear Information System (INIS)

    Dahlgen, F.; Citrolo, J.; Knutson, D.; Kalish, M.

    1992-01-01

    A preliminary analysis of the response of the BPX machine structure to a seismic input was performed. MSC/NASTRAN 5 , a general purpose XXX element computer code, has been used. The purpose of this paper is to assess the probable range of seismically induced stresses and deflections in the machine substructure which connects the machine to the test cell floor, with particular emphasis on the shear pins which will be used to attach the TF coil modules to the machine substructure (for a more detailed description of the shear pins and structure see ref. 4 in these proceedings). The model was developed with sufficient detail to be used subsequently to investigate the transient response to various dynamic loading conditions imposed on the structure by the PF, TF, and Vacuum Vessel, during normal and off-normal operations. The model does not include the mass and stiffness of the building or the building-soil interaction and as such can only be considered an interim assessment of the dynamic response of the machine to the S.S.E.(this is the Safe Shutdown Earthquake which is also the Design XXX Earthquake for all major structural components)

  16. Flight Dynamics Analysis for Leonardo-BRDF

    Science.gov (United States)

    Hughes, Steven P.; Mailhe, Laurie; Bauer, Frank H. (Technical Monitor)

    2000-01-01

    Leonardo-BRDF (Bidirectional Reflectance Distribution Function) is a new NASA mission concept proposed to allow the investigation of radiative transfer and its effect on the Earth's climate and atmospheric phenomenon. Enabled by the recent developments in small-satellite and formation flying technology, the mission is envisioned to be composed of an array of spacecraft in carefully designed orbits. The different perspectives provided by a distributed array of spacecraft offer a unique advantage to study the Earth's albedo. This paper presents the flight dynamics analysis performed in the context of the Leonardo-BRDF science requirements. First, the albedo integral is investigated and the effect of viewing geometry on science return is studied. The method used in this paper, based on Gauss quadrature, provides the optimal formation geometry to ensure that the value of the integral is accurately approximated. An orbit design approach is presented to achieve specific relative orbit geometries while simultaneously satisfying orbit dynamics constraints to reduce formation-keeping fuel expenditure. The relative geometry afforded by the design is discussed in terms of mission requirements. An optimal Lambert initialization scheme is presented with the required Delta-V to distribute all spacecraft from a common parking orbit into their appropriate orbits in the formation. Finally, formation-keeping strategies are developed and the associated Delta-V's are calculated to maintain the formation in the presence of perturbations.

  17. A dynamic phase microscopic study of optical characteristics of individual chloroplasts.

    Science.gov (United States)

    Tychinsky, V P; Kretushev, A V; Vyshenskaya, T V; Tikhonov, A N

    2004-10-11

    Dynamic phase microscopy (DPM) allows the monitoring of optical path difference (or phase height), h(x,y,t) approximately integraln(x,y,z,t)dz, an integral refractive index projection of the medium, n(x,y,z,t), in optically transparent biological specimens at high spatial and temporal resolutions. In this study, DPM was used for the analysis of fluctuations in the optical characteristics of individual bean chloroplasts in various metabolic states. A "phase image" of an individual chloroplast, which represents a three-dimensional plot of the "phase height", was obtained for the first time, and the frequency spectra of the fluctuations of h(x,y,t) were investigated. The fluctuation patterns, i.e., the intensity and the frequency spectra of phase height fluctuations in bean chloroplasts (Class B) were found to depend on their metabolic state. Under conditions of noncyclic (or pseudocyclic) electron transport, the fluctuations displayed characteristic frequencies in the range of 0.25-0.6 Hz and were space-time-correlated in the chloroplast domains with the cross sizes of approximately 2 microm. The fluctuation intensity decreased in the presence of uncouplers (nigericin and valinomycin, 20 microM). A stronger (in comparison with 20 microM valinomycin) effect of 20 microM nigericin suggests that the light-induced generation of the transmembrane pH difference (DeltapH) makes the main contribution to the increment of space-correlated fluctuations of h(x,y,t). Studies of chloroplasts incubated in media of various osmolarity (50-500 mM sucrose) have shown that structural changes in thylakoids are among other factors responsible for phase height fluctuations.

  18. PIXEL ANALYSIS OF PHOTOSPHERIC SPECTRAL DATA. I. PLASMA DYNAMICS

    Energy Technology Data Exchange (ETDEWEB)

    Rasca, Anthony P.; Chen, James [Plasma Physics Division, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Pevtsov, Alexei A., E-mail: anthony.rasca.ctr@nrl.navy.mil [National Solar Observatory, Sunspot, NM 88349 (United States)

    2016-11-20

    Recent observations of the photosphere using high spatial and temporal resolution show small dynamic features at or below the current resolving limits. A new pixel dynamics method has been developed to analyze spectral profiles and quantify changes in line displacement, width, asymmetry, and peakedness of photospheric absorption lines. The algorithm evaluates variations of line profile properties in each pixel and determines the statistics of such fluctuations averaged over all pixels in a given region. The method has been used to derive statistical characteristics of pixel fluctuations in observed quiet-Sun regions, an active region with no eruption, and an active region with an ongoing eruption. Using Stokes I images from the Vector Spectromagnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) telescope on 2012 March 13, variations in line width and peakedness of Fe i 6301.5 Å are shown to have a distinct spatial and temporal relationship with an M7.9 X-ray flare in NOAA 11429. This relationship is observed as stationary and contiguous patches of pixels adjacent to a sunspot exhibiting intense flattening in the line profile and line-center displacement as the X-ray flare approaches peak intensity, which is not present in area scans of the non-eruptive active region. The analysis of pixel dynamics allows one to extract quantitative information on differences in plasma dynamics on sub-pixel scales in these photospheric regions. The analysis can be extended to include the Stokes parameters and study signatures of vector components of magnetic fields and coupled plasma properties.

  19. Dynamic Error Analysis Method for Vibration Shape Reconstruction of Smart FBG Plate Structure

    Directory of Open Access Journals (Sweden)

    Hesheng Zhang

    2016-01-01

    Full Text Available Shape reconstruction of aerospace plate structure is an important issue for safe operation of aerospace vehicles. One way to achieve such reconstruction is by constructing smart fiber Bragg grating (FBG plate structure with discrete distributed FBG sensor arrays using reconstruction algorithms in which error analysis of reconstruction algorithm is a key link. Considering that traditional error analysis methods can only deal with static data, a new dynamic data error analysis method are proposed based on LMS algorithm for shape reconstruction of smart FBG plate structure. Firstly, smart FBG structure and orthogonal curved network based reconstruction method is introduced. Then, a dynamic error analysis model is proposed for dynamic reconstruction error analysis. Thirdly, the parameter identification is done for the proposed dynamic error analysis model based on least mean square (LMS algorithm. Finally, an experimental verification platform is constructed and experimental dynamic reconstruction analysis is done. Experimental results show that the dynamic characteristics of the reconstruction performance for plate structure can be obtained accurately based on the proposed dynamic error analysis method. The proposed method can also be used for other data acquisition systems and data processing systems as a general error analysis method.

  20. Dynamic analysis and qualification test of nuclear components

    International Nuclear Information System (INIS)

    Kim, B.K.; Lee, C.H.; Park, S.H.; Kim, Y.M.; Kim, B.S.; Kim, I.G.; Chung, C.W.; Kim, Y.M.

    1981-01-01

    This report contains the study on the dynamic characteristics of Wolsung fuel rod and on the dynamic balancing of rotating machinery to evaluate the performance of nuclear reactor components. The study on the dynamic characteristics of Wolsung fuel rod was carried out by both experimental and theoretical methods. Forced vibration testing of actual Wolsung fuel rod using sine sweep and sine dwell excitation was conducted to find the dynamic and nonlinear characteristics of the fuel rod. The data obtained by the test were used to analyze the nonlinear impact characteristics of the fuel rod which has a motion-constraint stop in the center of the rod. The parameters used in the test were the input force level of the exciter, the clearance gap between the fuel rod and the motion constraints, and the frequencies. Test results were in good agreement with the analytical results

  1. Dynamic Analysis of Mobile Device Applications

    Energy Technology Data Exchange (ETDEWEB)

    Corey Thuen

    2013-01-01

    The On-Device Dynamic Analysis of Mobile Applications (ODAMA) project was started in an effort to protect mobile devices used in Industrial Control Systems (ICS) from cyber attack. Because mobile devices hide as much of the “computer” as possible, the user’s ability to assess the software running on their system is limited. The research team chose Google’s Android platform for this initial research because it is open source and it would give us freedom in our approach, including the ability to modify the mobile device’s operating system itself. The research team concluded that a Privileged Application was the right approach, and the result was ODAMA. This project is an important piece of the work to secure the expanding use of mobile devices with our nation’s critical infrastructure.

  2. Metrical and dynamical aspects in complex analysis

    CERN Document Server

    2017-01-01

    The central theme of this reference book is the metric geometry of complex analysis in several variables. Bridging a gap in the current literature, the text focuses on the fine behavior of the Kobayashi metric of complex manifolds and its relationships to dynamical systems, hyperbolicity in the sense of Gromov and operator theory, all very active areas of research. The modern points of view expressed in these notes, collected here for the first time, will be of interest to academics working in the fields of several complex variables and metric geometry. The different topics are treated coherently and include expository presentations of the relevant tools, techniques and objects, which will be particularly useful for graduate and PhD students specializing in the area.

  3. Dynamic analysis of stochastic transcription cycles.

    Directory of Open Access Journals (Sweden)

    Claire V Harper

    2011-04-01

    Full Text Available In individual mammalian cells the expression of some genes such as prolactin is highly variable over time and has been suggested to occur in stochastic pulses. To investigate the origins of this behavior and to understand its functional relevance, we quantitatively analyzed this variability using new mathematical tools that allowed us to reconstruct dynamic transcription rates of different reporter genes controlled by identical promoters in the same living cell. Quantitative microscopic analysis of two reporter genes, firefly luciferase and destabilized EGFP, was used to analyze the dynamics of prolactin promoter-directed gene expression in living individual clonal and primary pituitary cells over periods of up to 25 h. We quantified the time-dependence and cyclicity of the transcription pulses and estimated the length and variation of active and inactive transcription phases. We showed an average cycle period of approximately 11 h and demonstrated that while the measured time distribution of active phases agreed with commonly accepted models of transcription, the inactive phases were differently distributed and showed strong memory, with a refractory period of transcriptional inactivation close to 3 h. Cycles in transcription occurred at two distinct prolactin-promoter controlled reporter genes in the same individual clonal or primary cells. However, the timing of the cycles was independent and out-of-phase. For the first time, we have analyzed transcription dynamics from two equivalent loci in real-time in single cells. In unstimulated conditions, cells showed independent transcription dynamics at each locus. A key result from these analyses was the evidence for a minimum refractory period in the inactive-phase of transcription. The response to acute signals and the result of manipulation of histone acetylation was consistent with the hypothesis that this refractory period corresponded to a phase of chromatin remodeling which significantly

  4. Pressure Dynamic Characteristics of Pressure Controlled Ventilation System of a Lung Simulator

    Directory of Open Access Journals (Sweden)

    Yan Shi

    2014-01-01

    Full Text Available Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems.

  5. Pressure Dynamic Characteristics of Pressure Controlled Ventilation System of a Lung Simulator

    Science.gov (United States)

    Shi, Yan; Ren, Shuai; Cai, Maolin; Xu, Weiqing; Deng, Qiyou

    2014-01-01

    Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems. PMID:25197318

  6. Pressure dynamic characteristics of pressure controlled ventilation system of a lung simulator.

    Science.gov (United States)

    Shi, Yan; Ren, Shuai; Cai, Maolin; Xu, Weiqing; Deng, Qiyou

    2014-01-01

    Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems.

  7. Dynamic Chest Image Analysis: Model-Based Perfusion Analysis in Dynamic Pulmonary Imaging

    Directory of Open Access Journals (Sweden)

    Kiuru Aaro

    2003-01-01

    Full Text Available The "Dynamic Chest Image Analysis" project aims to develop model-based computer analysis and visualization methods for showing focal and general abnormalities of lung ventilation and perfusion based on a sequence of digital chest fluoroscopy frames collected with the dynamic pulmonary imaging technique. We have proposed and evaluated a multiresolutional method with an explicit ventilation model for ventilation analysis. This paper presents a new model-based method for pulmonary perfusion analysis. According to perfusion properties, we first devise a novel mathematical function to form a perfusion model. A simple yet accurate approach is further introduced to extract cardiac systolic and diastolic phases from the heart, so that this cardiac information may be utilized to accelerate the perfusion analysis and improve its sensitivity in detecting pulmonary perfusion abnormalities. This makes perfusion analysis not only fast but also robust in computation; consequently, perfusion analysis becomes computationally feasible without using contrast media. Our clinical case studies with 52 patients show that this technique is effective for pulmonary embolism even without using contrast media, demonstrating consistent correlations with computed tomography (CT and nuclear medicine (NM studies. This fluoroscopical examination takes only about 2 seconds for perfusion study with only low radiation dose to patient, involving no preparation, no radioactive isotopes, and no contrast media.

  8. Information model of trainee characteristics with definition of stochastic behavior of dynamic system

    Science.gov (United States)

    Sumin, V. I.; Smolentseva, T. E.; Belokurov, S. V.; Lankin, O. V.

    2018-03-01

    In the work the process of formation of trainee characteristics with their subsequent change is analyzed and analyzed. Characteristics of trainees were obtained as a result of testing for each section of information on the chosen discipline. The results obtained during testing were input to the dynamic system. The area of control actions consisting of elements of the dynamic system is formed. The limit of deterministic predictability of element trajectories in dynamical systems based on local or global attractors is revealed. The dimension of the phase space of the dynamic system is determined, which allows estimating the parameters of the initial system. On the basis of time series of observations, it is possible to determine the predictability interval of all parameters, which make it possible to determine the behavior of the system discretely in time. Then the measure of predictability will be the sum of Lyapunov’s positive indicators, which are a quantitative measure for all elements of the system. The components for the formation of an algorithm allowing to determine the correlation dimension of the attractor for known initial experimental values of the variables are revealed. The generated algorithm makes it possible to carry out an experimental study of the dynamics of changes in the trainee’s parameters with initial uncertainty.

  9. Simple estimating method of damages of concrete gravity dam based on linear dynamic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, T.; Kanenawa, K.; Yamaguchi, Y. [Public Works Research Institute, Tsukuba, Ibaraki (Japan). Hydraulic Engineering Research Group

    2004-07-01

    Due to the occurrence of large earthquakes like the Kobe Earthquake in 1995, there is a strong need to verify seismic resistance of dams against much larger earthquake motions than those considered in the present design standard in Japan. Problems exist in using nonlinear analysis to evaluate the safety of dams including: that the influence which the set material properties have on the results of nonlinear analysis is large, and that the results of nonlinear analysis differ greatly according to the damage estimation models or analysis programs. This paper reports the evaluation indices based on a linear dynamic analysis method and the characteristics of the progress of cracks in concrete gravity dams with different shapes using a nonlinear dynamic analysis method. The study concludes that if simple linear dynamic analysis is appropriately conducted to estimate tensile stress at potential locations of initiating cracks, the damage due to cracks would be predicted roughly. 4 refs., 1 tab., 13 figs.

  10. Studying the dynamical characteristics of pumps in NPP unit auxiliary water system under operational conditions

    International Nuclear Information System (INIS)

    Belyaev, S.G.; Puzanov, A.I.; Belikov, V.P.; Dizik, B.S.

    1990-01-01

    Hydrodynamic loads appearing in the flow-through part of pump aggregates of the system of auxiliary water supply in NPP with variations in the operation modes are investigated. It is shown that during operation of centrifugal pumps the position of the mode on the pump characteristic plot must be controlled. When the mode point exceeds the limits of the working zone it results in a considerable increase of dynamic loads: pressure pulsation and vibration. As the flow rate increase the decrease in dynamic loads is recorded at low frequencies of about 2-4 Hz

  11. Passivhaus: indoor comfort and energy dynamic analysis.

    Science.gov (United States)

    Guida, Antonella; Pagliuca, Antonello; Cardinale, Nicola; Rospi, Gianluca

    2013-04-01

    The research aims to verify the energy performance as well as the indoor comfort of an energy class A+ building, built so that the sum of the heat passive contributions of solar radiation, transmitted through the windows, and the heat generated inside the building, are adeguate to compensate for the envelope loss during the cold season. The building, located in Emilia Romagna (Italy), was built using a wooden structure, an envelope realized using a pinewood sandwich panels (transmittance U = 0.250 W/m2K) and, inside, a wool flax insulation layer and thermal window frame with low-emissivity glass (U = 0524 W/m2K). The building design and construction process has followed the guidelines set by "CasaClima". The building has been modeled in the code of dynamic calculation "Energy Plus" by the Design Builder application and divided it into homogenous thermal zones, characterized by winter indoor temperature set at 20 ° (+ / - 1 °) and summer indoor temperature set at 26 ° (+ / - 1 °). It has modeled: the envelope, as described above, the "free" heat contributions, the air conditioning system, the Mechanical Ventilation system as well as home automation solutions. The air conditioning system is an heat pump, able to guarantee an optimization of energy consumption (in fact, it uses the "free" heat offered by the external environment for conditioning indoor environment). As regards the air recirculation system, it has been used a mechanical ventilation system with internal heat cross-flow exchanger, with an efficiency equal to 50%. The domotic solutions, instead, regard a system for the control of windows external screening using reeds, adjustable as a function of incident solar radiation and a lighting management system adjusted automatically using a dimmer. A so realized building meets the requirement imposed from Italian standard UNI/TS 11300 1, UNI/TS 11300 2 and UNI/TS 11300 3. The analysis was performed according to two different configurations: in "spontaneous

  12. Dynamics of Coarse Woody Debris Characteristics in the Qinling Mountain Forests in China

    Directory of Open Access Journals (Sweden)

    Jie Yuan

    2017-10-01

    Full Text Available Coarse woody debris (CWD is an essential component in defining the structure and function of forest ecosystems. Long-term dynamics of CWD characteristics not only affect the release rates of chemical elements from CWD, but also the species diversity of inhabiting plants, animals, insects, and microorganisms as well as the overall health of ecosystems. However, few quantitative studies have been done on the long-term dynamics of CWD characteristics in forest ecosystems in China. In this study, we conducted nine tree censuses between 1996 and 2016 at the Huoditang Experimental Forest in the Qinling Mountains of China. We quantified forest biomass including CWD and CWD characteristics such as decay states and diameter classes during this period and correlated with stand, site, and climatic variables. The forest biomass was dominated by live tree biomass (88%; followed by CWD mass (6%–10%. Understory biomass contributed only a small portion (1%–4% of the overall biomass. Significant differences in average annual increment of CWD mass were found among forest stands of different species (p < 0.0001. Forest biomass, stand age, forest type, aspect, slope, stand density, annual average temperature, and precipitation were all significantly correlated with CWD mass (p < 0.05, with forest type exhibiting the strongest correlation (r2 = 0.8256. Over time, the annual mass of different CWD characteristics increased linearly from 1996–2016 across all forest types. Our study revealed that forest biomass, including CWD characteristics, varied by forest type. Stand and site characteristics (forest biomass, forest type, aspect, slope and stand density along with temperature and precipitation played a major role in the dynamics of CWD in the studied forest ecosystems.

  13. Physical characteristics of conditioned anaerobic digested sludge - A fractal,transient and dynamic rheological viewpoint

    Institute of Scientific and Technical Information of China (English)

    Yili Wang; Emilie Dieude-Fauvel; Steven K Dentel

    2011-01-01

    The changes in the physical characteristics of unconditioned and conditioned anaerobic digested sludge (ADS) biosolids,such as capillary suction time (CST),yield stress,average size and fractal dimensions,were investigated through a CST test,transient and dynamic rheological test and image analysis.The results showed that the optimum polymer dose range was observed when CST or its reciprocal value was employed as an indicator.There were good correlations between the yield stresses determined from both a controlled shear stress test and a strain amplitude sweep test.The yield stress and storage modulus (G') increased as the polymer dose increased in most cases.A frequency sweep test revealed that polymer conditioning could extend the frequency sweep ranges for their elastic behaviors over viscous behaviors as well as the gel-like structure in the linear viscoelastic range.These results implied that more deformation energy was stored in this rigid structure,and that elastic behavior became increasingly dominant with the addition of the polymer in most cases.In addition,both the average sizes and two-dimensional fractal dimensions for conditioned ADS biosolids presented a similar up-climax-down variation trend as the polymer doses increased,whereas the critical polymer doses at the highest average sizes or two-dimensional fractal dimensions,were different.Correlation analysis revealed that the conditioned ADS dewaterability was not correlated with the yield stresses,while the average sizes or the two-dimensional fractal dimensions for conditioned ADS biosolids could be taken as the indication parameters for ADS dewaterability.

  14. A study on the change in dynamic characteristics of reactor internals

    International Nuclear Information System (INIS)

    Kim, Tae Ryong; Jung, Seung Ho; Park, Jin Ho; Park, Jin Suk; Jeong, Keong Hoon

    1993-12-01

    An experimental and analytical studies were performed to establish the relationship between in-air dynamic characteristics of reactor internals and in-water ones by using a scaled-down model which consists of CSB (flexible) and RPV (rigid) models. The experimental results show that the natural frequencies of the CSB model in water are remarkably lowered than those in air, and the normalized natural frequency (in-water frequency/in-air frequency) of the CSB model exists between in-phase mode and out-of-phase mode values of the flexible-to-flexible co-axial cylindrical structure which has the same dimensions as the scaled-down model. The normalized frequency increases to asymptotically reach the in-phase mode frequency of the flexible co-axial cylindrical structure as circumferential mode number (n) increases, while decreases to come near of the out-of-phase mode value as the circumferential mode number decreases. The support condition change for the CSB model in waster made the frequency of 1st axial mode (pure beam mode) shifted into lower value without any effect on the other modes. The changing trend of the natural frequencies and the mode shapes resulted from the finite element analysis by using the ANSYS code shows good agreement with the experimental results both in air and in water cases. In addition, a theoretical study was also performed by simplifying the scaled-down model as flexible-to-rigid co-axial cylindrical structure. It is found that the in-air natural frequencies shows good agreement with both the experimental and finite element analysis results, while the in-water frequencies reveals rather discrepancies. (Author)

  15. Dynamic contrast-enhanced MR imaging in osteoid osteoma: relationships with clinical and CT characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Pottecher, P. [Hopital Lariboisiere, AP-HP, Department of Osteoarticular Radiology, Paris (France); Hopital du Bocage, Department of Vascular, Oncologic and Interventional Radiology, Dijon (France); Sibileau, E.; Hamze, B.; Parlier, C.; Laredo, J.D.; Bousson, V. [Hopital Lariboisiere, AP-HP, Department of Osteoarticular Radiology, Paris (France); Aho, S. [Hopital du Bocage, Hospital Hygiene and Epidemiology unit, Dijon (France)

    2017-07-15

    To correlate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) features to clinical and computed tomography (CT) morphological features of osteoid osteoma (OO). Our institutional review board approved this retrospective study, waiving the need for informed consent. We included the 102 patients treated with interstitial laser ablation for histologically documented OO at our institution in 2008-2013. DCE-MRI variables were the time-enhancement pattern and rising slope (Slope{sub rise}) and CT variables were the bone and segment involved (OO{sub bone} and OO{sub segment,} respectively), OO location relative to the native cortex (OO{sub cortex}), nidus surface area, vessel sign, and largest neighboring-vessel diameter (Dmax{sub vessel}). Descriptive statistics and correlations linking DCE-MRI findings to clinical and CT characteristics were computed. DCE-MRI showed early arterial peak enhancement in 95 (93%) cases, with a mean Slope{sub rise} of 9.30 ± 8.10. CT visualized a vessel sign in 84 (82%) cases with a mean Dmax{sub vessel} of 1.10 ± 0.60 mm. By univariate analysis, Slope{sub rise} correlated significantly with pain duration and Dmax{sub vessel} (r = 0.30, P = 0.003; and r = 0.22, P = 0.03; respectively). Analysis of variance showed that Slope{sub rise} correlated significantly with OO{sub bone} (P < 0.001), with a steeper slope for OOs located in short or flat bones. This study suggests more abundant vascularization of OOs with long-lasting pain and location on short or flat bones. (orig.)

  16. Nonlinear dynamics and bifurcation characteristics of shape memory alloy thin films subjected to in-plane stochastic excitation

    International Nuclear Information System (INIS)

    Zhu, Zhi-Wen; Zhang, Qing-Xin; Xu, Jia

    2014-01-01

    A kind of shape memory alloy (SMA) hysteretic nonlinear model was developed, and the nonlinear dynamics and bifurcation characteristics of the SMA thin film subjected to in-plane stochastic excitation were investigated. Van der Pol difference item was introduced to describe the hysteretic phenomena of the SMA strain–stress curves, and the nonlinear dynamic model of the SMA thin film subjected to in-plane stochastic excitation was developed. The conditions of global stochastic stability of the system were determined in singular boundary theory, and the probability density function of the system response was obtained. Finally, the conditions of stochastic Hopf bifurcation were analyzed. The results of theoretical analysis and numerical simulation indicate that self-excited vibration is induced by the hysteretic nonlinear characteristics of SMA, and stochastic Hopf bifurcation appears when the bifurcation parameter was changed; there are two limit cycles in the stationary probability density of the dynamic response of the system in some cases, which means that there are two vibration amplitudes whose probabilities are both very high, and jumping phenomena between the two vibration amplitudes appear with the change in conditions. The results obtained in this current paper are helpful for the application of the SMA thin film in stochastic vibration fields. - Highlights: • Hysteretic nonlinear model of shape memory alloy was developed. • Van der Pol item was introduced to interpret hysteretic strain–stress curves. • Nonlinear dynamic characteristics of the shape memory alloy film were analyzed. • Jumping phenomena were observed in the change of the parameters

  17. Dynamic voltage-current characteristics for a water jet plasma arc

    International Nuclear Information System (INIS)

    Yang Jiaxiang; Lan Sheng; Xu Zuoming

    2008-01-01

    A virtual instrument technology is used to measure arc current, arc voltage, dynamic V-I characteristics, and nonlinear conductance for a cone-shaped water jet plasma arc under ac voltage. Experimental results show that ac arc discharge mainly happens in water vapor evaporated from water when heated. However, due to water's cooling effect and its conductance, arc conductance, reignition voltage, extinguish voltage, and current zero time are very different from those for ac arc discharge in gas work fluid. These can be valuable to further studies on mechanism and characteristics of plasma ac discharge in water, and even in gas work fluid

  18. Dynamic characteristics of a flywheel energy storage system using superconducting magnetic bearings

    CERN Document Server

    Kim, J S

    2003-01-01

    The high-temperature superconducting magnetic bearing flywheel energy storage system (SMB-FESS) is proposed as an efficient energy storage system. It is important to identify the dynamic behaviour and the characteristics of the SMB-FESS. First, a new method for identifying SMB characteristics has been suggested. The suggested modelling method is verified by comparing the experimental and analytical frequency response functions. In this study, the analyses of critical speed and unbalance response are performed using the analytical model. The experimental test has been carried out to verify the result of simulation. A good agreement has been observed between the experiment and the simulation result.

  19. Research on structural dynamic characteristics of continuous steel box girder-bridge with lager ratio of wide-span

    Directory of Open Access Journals (Sweden)

    Yin Haijun

    2018-01-01

    Full Text Available Structure natural frequency and mode of vibration can not only reflect the structure modal parameters of dynamic properties, but also incarnate the dynamic evaluation characteristics of bridge structure. This paper applies ANSYS to establish the finite element model based on a continuous steel box girder bridge in order to obtain the corresponding modal analysis parameters. Through the environmental stimulation test, The results show that height of the steel box girder and the setting of diaphragm plate is reasonable, transverse space of piers not merely provide enough support but also ensure lateral stability of the bridge, as well as offering aside the maximum lateral clearance of the existing road. Meanwhile, the calculation results have important engineering practical values. which can provide basic data for the design, construction and maintenance of similar Bridges.

  20. Fractal Characteristics Analysis of Blackouts in Interconnected Power Grid

    DEFF Research Database (Denmark)

    Wang, Feng; Li, Lijuan; Li, Canbing

    2018-01-01

    The power failure models are a key to understand the mechanism of large scale blackouts. In this letter, the similarity of blackouts in interconnected power grids (IPGs) and their sub-grids is discovered by the fractal characteristics analysis to simplify the failure models of the IPG. The distri......The power failure models are a key to understand the mechanism of large scale blackouts. In this letter, the similarity of blackouts in interconnected power grids (IPGs) and their sub-grids is discovered by the fractal characteristics analysis to simplify the failure models of the IPG....... The distribution characteristics of blackouts in various sub-grids are demonstrated based on the Kolmogorov-Smirnov (KS) test. The fractal dimensions (FDs) of the IPG and its sub-grids are then obtained by using the KS test and the maximum likelihood estimation (MLE). The blackouts data in China were used...

  1. Research progress of laser welding process dynamic monitoring technology based on plasma characteristics signal

    Directory of Open Access Journals (Sweden)

    Teng WANG

    2017-02-01

    Full Text Available During the high-power laser welding process, plasmas are induced by the evaporation of metal under laser radiation, which can affect the coupling of laser energy and the workpiece, and ultimately impact on the reliability of laser welding quality and process directly. The research of laser-induced plasma is a focus in high-power deep penetration welding field, which provides a promising research area for realizing the automation of welding process quality inspection. In recent years, the research of laser welding process dynamic monitoring technology based on plasma characteristics is mainly in two aspects, namely the research of plasma signal detection and the research of laser welding process modeling. The laser-induced plasma in the laser welding is introduced, and the related research of laser welding process dynamic monitoring technology based on plasma characteristics at home and abroad is analyzed. The current problems in the field are summarized, and the future development trend is put forward.

  2. Study on Spray Characteristics and Spray Droplets Dynamic Behavior of Diesel Engine Fueled by Rapeseed Oil

    Directory of Open Access Journals (Sweden)

    Sapit Azwan

    2014-07-01

    Full Text Available Fuel-air mixing is important process in diesel combustion. It directly affects the combustion and emission of diesel engine. Biomass fuel needs great help to atomize because the fuel has high viscosity and high distillation temperature. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fueled by rapeseed oil (RO. Optical observation of RO spray was carried out using shadowgraph photography technique. Single nano-spark photography technique was used to study the characteristics of the rapeseed oil spray while dual nano-spark shadowgraph technique was used to study the spray droplet behavior. The results show that RO has very poor atomization due to the high viscosity nature of the fuel. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy.

  3. Identifying protein complex by integrating characteristic of core-attachment into dynamic PPI network.

    Directory of Open Access Journals (Sweden)

    Xianjun Shen

    Full Text Available How to identify protein complex is an important and challenging task in proteomics. It would make great contribution to our knowledge of molecular mechanism in cell life activities. However, the inherent organization and dynamic characteristic of cell system have rarely been incorporated into the existing algorithms for detecting protein complexes because of the limitation of protein-protein interaction (PPI data produced by high throughput techniques. The availability of time course gene expression profile enables us to uncover the dynamics of molecular networks and improve the detection of protein complexes. In order to achieve this goal, this paper proposes a novel algorithm DCA (Dynamic Core-Attachment. It detects protein-complex core comprising of continually expressed and highly connected proteins in dynamic PPI network, and then the protein complex is formed by including the attachments with high adhesion into the core. The integration of core-attachment feature into the dynamic PPI network is responsible for the superiority of our algorithm. DCA has been applied on two different yeast dynamic PPI networks and the experimental results show that it performs significantly better than the state-of-the-art techniques in terms of prediction accuracy, hF-measure and statistical significance in biology. In addition, the identified complexes with strong biological significance provide potential candidate complexes for biologists to validate.

  4. Analysis of dendrometric characteristics of Acacia senegal (L.) Willd ...

    African Journals Online (AJOL)

    The study gives an analysis of the dendrometric parameters of a middle Sahelian species (Acacia senegal) in semi-arid environment to get better knowledge of its behavior. The research lays the principle that the species behaves differently according to the ecogeographical stations. So, its characteristics change from one ...

  5. The energy distribution structure and dynamic characteristics of energy release in electrostatic discharge process

    OpenAIRE

    Liu, Qingming; Shao, Huige; Zhang, Yunming

    2015-01-01

    The detail structure of energy output and the dynamic characteristics of electric spark discharge process have been studied to calculate the energy of electric spark induced plasma under different discharge condition accurately. A series of electric spark discharge experiments were conducted with the capacitor stored energy in the range of 10J 100J and 1000J respectively. And the resistance of wire, switch and plasma between electrodes were evaluated by different methods. An optimized method ...

  6. Some imaging characteristics of the dynamic spatial reconstructor X-ray scanner system

    International Nuclear Information System (INIS)

    Behrenbeck, T.; Sinak, L.J.; Robb, R.A.; Kinsey, J.H.; Ritman, E.L.

    1984-01-01

    In late 1979, the Dynamic Spatial Reconstructor (DSR), a multiple X-ray source, stop action, volume scanning imaging device was installed. At present, the operational characteristics and biomedical utility of the DSR are being evaluated. This research project involves scanning experimental animals and carefully selected patients with cardiovascular and pulmonary pathology. The DSR scanner utilizes a computerized transaxial tomography principle to generate images of transverse slices of the body. (Auth.)

  7. Molecular dynamics simulation aiming at interfacial characteristics of polymer chains on nanotubes with different layers

    Science.gov (United States)

    Li, Kun; Gu, Boqin; Zhu, Wanfu

    2017-03-01

    A molecular dynamics (MD) simulations study is performed on multiwalled carbon nanotubes (MWNTs)/acrylonitrile-butadiene rubber (NBR) composites. The physisorption and interfacial characteristics between the various MWNTs and polymer macromolecular chains are identified. The effects of nanotube layers on the nanotubes/polymer interactions are examined. Each of the situation result and surface features is characterized by binding energy (Eb). It is shown that the binding energy (Eb) increase with the number of layers.

  8. Variation of beam characteristics for physical and enhanced dynamic wedge from a dual energy accelerator

    International Nuclear Information System (INIS)

    Varatharaj, C.; Ravikumar, M.; Sathiyan, S.; Supe, Sanjay S.

    2008-01-01

    The use of Megavoltage X-ray sources of radiation, with their skin-sparing qualities in radiation therapy has been a boon in relieving patient discomfort and allowing higher tumor doses to be given with fewer restrictions due to radiation effects in the skin. The aim of this study was to compare few of the dosimetric characteristics of a physical and enhanced dynamic wedge from a dual energy (6-18 MV) linear accelerator

  9. Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing

    OpenAIRE

    Liu, Ren; Wang, Xiao-Li; Zhang, Xiao-Qing

    2012-01-01

    The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that ...

  10. [Quantitative spectrum analysis of characteristic gases of spontaneous combustion coal].

    Science.gov (United States)

    Liang, Yun-Tao; Tang, Xiao-Jun; Luo, Hai-Zhu; Sun, Yong

    2011-09-01

    Aimed at the characteristics of spontaneous combustion gas such as a variety of gases, lou limit of detection, and critical requirement of safety, Fourier transform infrared (FTIR) spectral analysis is presented to analyze characteristic gases of spontaneous combustion In this paper, analysis method is introduced at first by combing characteristics of absorption spectra of analyte and analysis requirement. Parameter setting method, sample preparation, feature variable abstract and analysis model building are taken into consideration. The methods of sample preparation, feature abstraction and analysis model are introduced in detail. And then, eleven kinds of gases were tested with Tensor 27 spectrometer. CH4, C2H6, C3H8, iC4H10, nC4H10, C2 H4, C3 H6, C3 H2, SF6, CO and CO2 were included. The optical path length was 10 cm while the spectra resolution was set as 1 cm(-1). The testing results show that the detection limit of all analytes is less than 2 x 10(-6). All the detection limits fit the measurement requirement of spontaneous combustion gas, which means that FTIR may be an ideal instrument and the analysis method used in this paper is competent for spontaneous combustion gas measurement on line.

  11. Damping capacity and dynamic mechanical characteristics of the plasma-sprayed coatings

    International Nuclear Information System (INIS)

    Yu Liming; Ma Yue; Zhou Chungen; Xu Huibin

    2005-01-01

    The damping properties and dynamic mechanical performance of NiCrAlY coating, FeCrMo ferromagnetic coating, AlCuFeCr quasicrystalline coating and nanostructured ZrO 2 ceramic coating, which were prepared by plasma-spray method, were investigated. The measuring results of the dynamic mechanical thermal analyzer (DMTA) and the flexural resonance testing method show that the damping capacity (Q -1 ) of the coated sample has a notable improvement compared to the substrate, while the dynamic modulus has a dramatic decrease. The resonance frequency of the coated cantilever beam structure shifted to high-frequency, and the resonance amplitude, especially high mode resonance, was dramatically attenuated. The internal friction peaks were observed in the Q -1 -temperature spectrogram and a normal amplitude effects were shown in the coated samples damping characteristics. The damping mechanism based on the interaction between substrate and coating layer, and the microstructure of the coated sample were also discussed in this paper

  12. Effect of driving voltage polarity on dynamic response characteristics of electrowetting liquid lens

    Science.gov (United States)

    Na, Xie; Ning, Zhang; Rong-Qing, Xu

    2018-05-01

    A test device is developed for studying the dynamic process of an electrowetting liquid lens. By analyzing the light signals through the liquid lens, the dynamical properties of the lens are investigated. In our experiment, three types of pulse, i.e., sine, bipolar pulse, and single pulse signals, are employed to drive the liquid lens, and the dynamic characteristics of the lens are subsequently analyzed. The results show that the positive and negative polarities of the driving voltage can cause a significant difference in the response of the liquid lens; meanwhile, the lens’s response to the negative polarity of the driving voltage is clearer. We use the theory of charge restraint to explain this phenomenon, and it is concluded that the negative ions are more easily restrained by a dielectric layer. This work gives direct guidance for practical applications based on an electrowetting liquid lens.

  13. Modelling and Analysis of a New Piezoelectric Dynamic Balance Regulator

    Directory of Open Access Journals (Sweden)

    Mu-Xun Xu

    2012-11-01

    Full Text Available In this paper, a new piezoelectric dynamic balance regulator, which can be used in motorised spindle systems, is presented. The dynamic balancing adjustment mechanism is driven by an in-plane bending vibration from an annular piezoelectric stator excited by a high-frequency sinusoidal input voltage. This device has different construction, characteristics and operating principles than a conventional balance regulator. In this work, a dynamic model of the regulator is first developed using a detailed analytical method. Thereafter, MATLAB is employed to numerically simulate the relations between the dominant parameters and the characteristics of the regulator based on thedynamic model. Finally, experimental measurements are used to certify the validity of the dynamic model. Consequently, the mathematical model presented and analysed in this paper can be used as a tool for optimising the design of a piezoelectric dynamic balance regulator during steady state operation.

  14. Aerodynamic shape optimization for alleviating dynamic stall characteristics of helicopter rotor airfoil

    Directory of Open Access Journals (Sweden)

    Wang Qing

    2015-04-01

    Full Text Available In order to alleviate the dynamic stall effects in helicopter rotor, the sequential quadratic programming (SQP method is employed to optimize the characteristics of airfoil under dynamic stall conditions based on the SC1095 airfoil. The geometry of airfoil is parameterized by the class-shape-transformation (CST method, and the C-topology body-fitted mesh is then automatically generated around the airfoil by solving the Poisson equations. Based on the grid generation technology, the unsteady Reynolds-averaged Navier-Stokes (RANS equations are chosen as the governing equations for predicting airfoil flow field and the highly-efficient implicit scheme of lower–upper symmetric Gauss–Seidel (LU-SGS is adopted for temporal discretization. To capture the dynamic stall phenomenon of the rotor more accurately, the Spalart–Allmaras turbulence model is employed to close the RANS equations. The optimized airfoil with a larger leading edge radius and camber is obtained. The leading edge vortex and trailing edge separation of the optimized airfoil under unsteady conditions are obviously weakened, and the dynamic stall characteristics of optimized airfoil at different Mach numbers, reduced frequencies and angles of attack are also obviously improved compared with the baseline SC1095 airfoil. It is demonstrated that the optimized method is effective and the optimized airfoil is suitable as the helicopter rotor airfoil.

  15. The dynamic current-voltage characteristic as a powerful tool to analyze fast phenomena in plasma

    International Nuclear Information System (INIS)

    Ivan, L. M.; Mihai-Plugaru, M.; Amarandei, G.; Aflori, M.; Dimitriu, D. G.

    2006-01-01

    The static current-voltage characteristic of an electrode immersed in plasma is obtained by slowly increasing and subsequently decreasing the potential on the electrode with respect to the plasma potential or the ground. This characteristic can give us important information about the phenomena that take place in front of the electrode. Current jumps can be evidenced which were often associated with an hysteresis effect, regions with S-type or N-type negative differential resistance, etc. The method is always used when we investigate the appearance of complex space charge configurations (CSCC) in front of an electrode immersed in plasma. However, to investigate the dynamics of such structures or other fast phenomena (like instabilities) which take place in plasma devices with frequencies of tenth, hundred kHz or more, complex investigation techniques must be used. One of the most efficient methods to investigate fast phenomena in plasma devices is the dynamic current-voltage characteristic. This is obtained by recording the time series of the current collected by the electrode when the voltage applied on it is very fast modified (most likely increased) by using a signal generator. In this way, very fast oscillations of the current can be recorded and new phenomena can be evidenced. We used this technique to study the phenomena which take place at the onset of electrostatic instabilities in Q-machine plasma, namely the potential relaxation instability (PRI) and the electrostatic ion-cyclotron instability (EICI). The obtained experimental results prove that the negative differential resistance region in the static current-voltage characteristic is the result of a nonlinear dynamics of a CSCC in form of a double layer (DL) which takes place just before the onset of the instabilities. In the case of the PRI we emphasized current jumps related with the DL appearance, which are not present in the static current-voltage characteristic at high plasma density. (authors)

  16. Electromechanical dynamic analysis for the drum driving system of the long-wall shearer

    Directory of Open Access Journals (Sweden)

    Changzhao Liu

    2015-10-01

    Full Text Available The drum driving system is one of the weakest parts of the long-wall shearer, and some methods are also needed to monitor and control the long-wall shearer to adapt to the important trend of unmanned operation in future mining systems. Therefore, it is essential to conduct an electromechanical dynamic analysis for the drum driving system of the long-wall shearer. First, a torsional dynamic model of planetary gears is proposed which is convenient to be connected to the electric motor model for electromechanical dynamic analysis. Next, an electromechanical dynamic model for the drum driving system is constructed including the electric motor, the gear transmission system, and the drum. Then, the electromechanical dynamic characteristics are simulated when the shock loads are acted on the drum driving system. Finally, some advices are proposed for improving the reliability, monitoring the operating state, and choosing the control signals of the long-wall shearer based on the simulation.

  17. Jerk analysis in rail vehicle dynamics

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Sharma

    2016-09-01

    Full Text Available The acceleration and deceleration of trains are essential for satisfactory performance of train services and for effective utilisation of line capacity by railways for a given network. However, it increases the risk of unbalancing the passengers. Therefore, in this paper, the jerk was analysed in the vehicle in order to examine its effect on safety and comfort to the passengers. For the purpose of this analysis, a rake with 24 ICF coaches fitted with CBC (H type tight lock and low preload draft gear hauled by WDP4 locomotive was considered. It was modelled using Universal Mechanism – a multibody dynamic software. Also, in addition, the vehicle is considered to be subjected to external forces such as rolling resistance, longitudinal wheel resistance, and gravitational force. The tractive and braking efforts for the locomotives are also considered with realistic track conditions between Lucknow and Kanpur of India. The presented results suggest that the CBC with balanced type draft gear reduces the jerk in the train.

  18. Dynamic analysis of three autoventilated disc brakes

    Directory of Open Access Journals (Sweden)

    Ricardo A. García-León

    2017-09-01

    Full Text Available The braking system of a car must meet several requirements, among which safety is the most important. It is also composed of a set of mechanical parts such as springs, different types of materials (Metallic and Non Metallic, gases and liquids. The brakes must work safely and predictably in all circumstances, which means having a stable level of friction, in any condition of temperature, humidity and salinity of the environment. For a correct design and operation of brake discs, it is necessary to consider different aspects, such as geometry, type of material, mechanical strength, maximum temperature, thermal deformation, cracking resistance, among others. Therefore, the main objective of this work is to analyze the dynamics and kinetics of the brake system from the pedal as the beginning of mathematical calculations to simulate the behavior and Analysis of Finite Elements (FEA, with the help of SolidWorks Simulation Software. The results show that the third brake disc works best in relation to the other two discs in their different working conditions such as speed and displacement in braking, concluding that depending on the geometry of the brake and the cooling channels these systems can be optimized that are of great importance for the automotive industry.

  19. Pharmaceutical applications of dynamic mechanical thermal analysis.

    Science.gov (United States)

    Jones, David S; Tian, Yiwei; Abu-Diak, Osama; Andrews, Gavin P

    2012-04-01

    The successful development of polymeric drug delivery and biomedical devices requires a comprehensive understanding of the viscoleastic properties of polymers as these have been shown to directly affect clinical efficacy. Dynamic mechanical thermal analysis (DMTA) is an accessible and versatile analytical technique in which an oscillating stress or strain is applied to a sample as a function of oscillatory frequency and temperature. Through cyclic application of a non-destructive stress or strain, a comprehensive understanding of the viscoelastic properties of polymers may be obtained. In this review, we provide a concise overview of the theory of DMTA and the basic instrumental/operating principles. Moreover, the application of DMTA for the characterization of solid pharmaceutical and biomedical systems has been discussed in detail. In particular we have described the potential of DMTA to measure and understand relaxation transitions and miscibility in binary and higher-order systems and describe the more recent applications of the technique for this purpose. © 2011 Elsevier B.V. All rights reserved.

  20. Dynamic analysis of the large deployable reflector

    Science.gov (United States)

    Calleson, Robert E.; Scott, A. Don

    1987-01-01

    The Large Deployable Reflector (LDR) is to be an astronomical observatory orbiting above Earth's obscuring atmosphere and operating in the spectral range between 30 microns and 1000 microns wavelength. The LDR will be used to study such astronomical phenomena as stellar and galactic formation, cosmology, and planetary atmospheres. The LDR will be the first observatory to be erected and assembled in space. This distinction brings with it several major technological challenges such as the development of ultra-lightweight deployable mirrors, advanced mirror fabrication techniques, advanced structures, and control of vibrations due to various sources of excitation. The purpose of this analysis is to provide an assessment of the vibrational response due to secondary mirror chopping and LDR slewing. The dynamic response of two 20-m LDR configurations was studied. Two mirror support configurations were investigated for the Ames concept, the first employs a six-strut secondary mirror support structure, while the second uses a triple-bipod support design. All three configurations were modeled using a tetrahedral truss design for the primary mirror support structure. Response resulting from secondary mirror chopping was obtained for the two Ames configurations, and the response of the primary mirror from slewing was obtained for all three configurations.

  1. Exploring Twitter communication dynamics with evolving community analysis

    Directory of Open Access Journals (Sweden)

    Konstantinos Konstantinidis

    2017-02-01

    Full Text Available Online Social Networks (OSNs have been widely adopted as a means of news dissemination, event reporting, opinion expression and discussion. As a result, news and events are being constantly reported and discussed online through OSNs such as Twitter. However, the variety and scale of all the information renders manual analysis extremely cumbersome, and therefore creating a storyline for an event or news story is an effort-intensive task. The main challenge pertains to the magnitude of data to be analyzed. To this end, we propose a framework for ranking the resulting communities and their metadata on the basis of structural, contextual and evolutionary characteristics such as community centrality, textual entropy, persistence and stability. We apply the proposed framework on three Twitter datasets and demonstrate that the analysis that followed enables the extraction of new insights with respect to influential user accounts, topics of discussion and emerging trends. These insights could primarily assist the work of social and political analysis scientists and the work of journalists in their own story telling, but also highlight the limitations of existing analysis methods and pose new research questions. To our knowledge, this study is the first to investigate the ranking of dynamic communities. In addition, our findings suggest future work regarding the determination of the general context of the communities based on structure and evolutionary behavior alone.

  2. Static and Dynamic Characteristics of DC-DC Converter Using a Digital Filter

    Science.gov (United States)

    Kurokawa, Fujio; Okamatsu, Masashi

    This paper presents the regulation and dynamic characteristics of the dc-dc converter with digital PID control, the minimum phase FIR filter or the IIR filter, and then the design criterion to improve the dynamic characteristics is discussed. As a result, it is clarified that the DC-DC converter using the IIR filter method has superior performance characteristics. The regulation range is within 1.3%, the undershoot against the step change of the load is less than 2% and the transient time is less than 0.4ms with the IIR filter method. In this case, the switching frequency is 100kHz and the step change of the load R is from 50 Ω to 10 Ω. Further, the superior characteristics are obtained when the first gain, the second gain and the second cut-off frequency are relatively large, and the first cut-off frequency and the passing frequency are relatively low. Moreover, it is important that the gain strongly decreases at the second cut-off frequency because the upper band pass frequency range must be always less than half of the sampling frequency based on the sampling theory.

  3. Possibilities of fractal analysis of the competitive dynamics: Approaches and procedures

    Science.gov (United States)

    Zagornaya, T. O.; Medvedeva, M. A.; Panova, V. L.; Isaichik, K. F.; Medvedev, A. N.

    2017-11-01

    The possibilities of the fractal approach are used for the study of non-linear nature of the competitive dynamics of the market of trading intermediaries. Based on a statistical study of the functioning of retail indicators in the region, the approach to the analysis of the characteristics of the competitive behavior of market participants is developed. The authors postulate the principles of studying the dynamics of competition as a result of changes in the characteristics of the vector and the competitive behavior of market agents.

  4. Dynamic and energetic characteristics of a bistable piezoelectric vibration energy harvester with an elastic magnifier

    Science.gov (United States)

    Wang, Guangqing; Liao, Wei-Hsin; Yang, Binqiang; Wang, Xuebao; Xu, Wentan; Li, Xiuling

    2018-05-01

    Bistable piezoelectric energy harvesters are being increasingly seen as an alternative to batteries in low-power devices. However, their energy harvesting characteristics are limited. To enhance these, we use a configuration including an elastic magnifier to amplify base excitation and provide sufficient kinetic energy to overcome potential well barriers, thus leading to large-amplitude bistable motion. We derive the distributed parameter mathematical model of this configuration by using Hamilton's principle. We then investigate the nonlinear dynamic behaviors and energetic characteristics and analyze the bifurcation for the equilibrium solution of the model. The simulations and experiments show high electromechanical responses and energy generation characteristics of the proposed system over a broad frequency band. The results suggest that, compared with a typical bistable piezoelectric energy harvester, the proposed energy harvester system with an elastic magnifier can provide higher output over a broader frequency band at lower excitation levels by adjusting the system's mass and stiffness ratios.

  5. How do task characteristics affect learning and performance? The roles of variably mapped and dynamic tasks.

    Science.gov (United States)

    Macnamara, Brooke N; Frank, David J

    2018-05-01

    For well over a century, scientists have investigated individual differences in performance. The majority of studies have focused on either differences in practice, or differences in cognitive resources. However, the predictive ability of either practice or cognitive resources varies considerably across tasks. We are the first to examine task characteristics' impact on learning and performance in a complex task while controlling for other task characteristics. In 2 experiments we test key theoretical task characteristic thought to moderate the relationship between practice, cognitive resources, and performance. We devised a task where each of several key task characteristics can be manipulated independently. Participants played 5 rounds of a game similar to the popular tower defense videogame Plants vs. Zombies where both cognitive load and game characteristics were manipulated. In Experiment 1, participants either played a consistently mapped version-the stimuli and the associated meaning of their properties were constant across the 5 rounds-or played a variably mapped version-the stimuli and the associated meaning of their properties changed every few minutes. In Experiment 2, participants either played a static version-that is, turn taking with no time pressure-or played a dynamic version-that is, the stimuli moved regardless of participants' response rates. In Experiment 1, participants' accuracy and efficiency were substantially hindered in the variably mapped conditions. In Experiment 2, learning and performance accuracy were hindered in the dynamic conditions, especially when under cognitive load. Our results suggest that task characteristics impact the relative importance of cognitive resources and practice on predicting learning and performance. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  6. Dynamic analysis of CHASNUPP steam generator structure during shipping

    International Nuclear Information System (INIS)

    Han Liangbi; Xu Jinkang; Zhou Meiwu; He Yinbiao

    1998-07-01

    The dynamic analysis of CHASNUPP steam generator during shipping is described, including the simplified mathematical model, acceleration power spectrum of ocean wave induced random vibration, the dynamic analysis of steam generator structure under random loading, the applied computer code and calculated results

  7. Dynamic analysis of elastic rubber tired car wheel breaking under variable normal load

    Science.gov (United States)

    Fedotov, A. I.; Zedgenizov, V. G.; Ovchinnikova, N. I.

    2017-10-01

    The purpose of the paper is to analyze the dynamics of the braking of the wheel under normal load variations. The paper uses a mathematical simulation method according to which the calculation model of an object as a mechanical system is associated with a dynamically equivalent schematic structure of the automatic control. Transfer function tool analyzing structural and technical characteristics of an object as well as force disturbances were used. It was proved that the analysis of dynamic characteristics of the wheel subjected to external force disturbances has to take into account amplitude and phase-frequency characteristics. Normal load variations impact car wheel braking subjected to disturbances. The closer slip to the critical point is, the higher the impact is. In the super-critical area, load variations cause fast wheel blocking.

  8. NMR Pore Structure and Dynamic Characteristics of Sandstone Caused by Ambient Freeze-Thaw Action

    Directory of Open Access Journals (Sweden)

    Bo Ke

    2017-01-01

    Full Text Available For a deeper understanding of the freeze-thaw weathering effects on the microstructure evolution and deterioration of dynamic mechanical properties of rock, the present paper conducted the nuclear magnetic resonance (NMR tests and impact loading experiments on sandstone under different freeze-thaw cycles. The results of NMR test show that, with the increase of freeze-thaw cycles, the pores expand and pores size tends to be uniform. The experimental results show that the stress-strain curves all go through four stages, namely, densification, elasticity, yielding, and failure. The densification curve is shorter, and the slope of elasticity curve decreases as the freeze-thaw cycles increase. With increasing freeze-thaw cycles, the dynamic peak stress decreases and energy absorption of sandstone increases. The dynamic failure form is an axial splitting failure, and the fragments increase and the size diminishes with increasing freeze-thaw cycles. The higher the porosity is, the more severe the degradation of dynamic characteristics is. An increase model for the relationships between the porosity or energy absorption and freeze-thaw cycles number was built to reveal the increasing trend with the freeze-thaw cycles increase; meanwhile, a decay model was built to predict the dynamic compressive strength degradation of rock after repeated freeze-thaw cycles.

  9. Simulation Analysis of Helicopter Ground Resonance Nonlinear Dynamics

    Science.gov (United States)

    Zhu, Yan; Lu, Yu-hui; Ling, Ai-min

    2017-07-01

    In order to accurately predict the dynamic instability of helicopter ground resonance, a modeling and simulation method of helicopter ground resonance considering nonlinear dynamic characteristics of components (rotor lead-lag damper, landing gear wheel and absorber) is presented. The numerical integral method is used to calculate the transient responses of the body and rotor, simulating some disturbance. To obtain quantitative instabilities, Fast Fourier Transform (FFT) is conducted to estimate the modal frequencies, and the mobile rectangular window method is employed in the predictions of the modal damping in terms of the response time history. Simulation results show that ground resonance simulation test can exactly lead up the blade lead-lag regressing mode frequency, and the modal damping obtained according to attenuation curves are close to the test results. The simulation test results are in accordance with the actual accident situation, and prove the correctness of the simulation method. This analysis method used for ground resonance simulation test can give out the results according with real helicopter engineering tests.

  10. Empirical analysis of scaling and fractal characteristics of outpatients

    International Nuclear Information System (INIS)

    Zhang, Li-Jiang; Liu, Zi-Xian; Guo, Jin-Li

    2014-01-01

    The paper uses power-law frequency distribution, power spectrum analysis, detrended fluctuation analysis, and surrogate data testing to evaluate outpatient registration data of two hospitals in China and to investigate the human dynamics of systems that use the “first come, first served” protocols. The research results reveal that outpatient behavior follow scaling laws. The results also suggest that the time series of inter-arrival time exhibit 1/f noise and have positive long-range correlation. Our research may contribute to operational optimization and resource allocation in hospital based on FCFS admission protocols.

  11. Empirical analysis of scaling and fractal characteristics of outpatients

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Li-Jiang, E-mail: zljjiang@gmail.com [College of Management and Economics, Tianjin University, Tianjin 300072 (China); Management Institute, Xinxiang Medical University, Xinxiang 453003, Henan (China); Liu, Zi-Xian, E-mail: liuzixian@tju.edu.cn [College of Management and Economics, Tianjin University, Tianjin 300072 (China); Guo, Jin-Li, E-mail: phd5816@163.com [Business School, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2014-01-31

    The paper uses power-law frequency distribution, power spectrum analysis, detrended fluctuation analysis, and surrogate data testing to evaluate outpatient registration data of two hospitals in China and to investigate the human dynamics of systems that use the “first come, first served” protocols. The research results reveal that outpatient behavior follow scaling laws. The results also suggest that the time series of inter-arrival time exhibit 1/f noise and have positive long-range correlation. Our research may contribute to operational optimization and resource allocation in hospital based on FCFS admission protocols.

  12. Scenario development, qualitative causal analysis and system dynamics

    Directory of Open Access Journals (Sweden)

    Michael H. Ruge

    2009-02-01

    Full Text Available The aim of this article is to demonstrate that technology assessments can be supported by methods such as scenario modeling and qualitative causal analysis. At Siemens, these techniques are used to develop preliminary purely qualitative models. These or parts of these comprehensive models may be extended to system dynamics models. While it is currently not possible to automatically generate a system dynamics models (or vice versa, obtain a qualitative simulation model from a system dynamics model, the two thechniques scenario development and qualitative causal analysis provide valuable indications on how to proceed towards a system dynamics model. For the qualitative analysis phase, the Siemens – proprietary prototype Computer – Aided Technology Assessment Software (CATS supportes complete cycle and submodel analysis. Keywords: Health care, telecommucations, qualitative model, sensitivity analysis, system dynamics.

  13. Analysis of Dynamic Stiffness of Bridge Cap-Pile System

    Directory of Open Access Journals (Sweden)

    Jinhui Chu

    2018-01-01

    Full Text Available In order to investigate the applicability of dynamic stiffness for bridge cap-pile system, a laboratory test was performed. A numerical model was also built for this type of system. The impact load was applied on the cap top and the dynamic stiffness was analysed. Then, the effect of the effective friction area between pile and soil was also considered. Finally, the dynamic stiffness relationship between the single pile and the cap-pile system was also compared. The results show that the dynamic stiffness is a sensitive index and can well reflect the static characteristics of the pile at the elastic stage. There is a significant positive correlation between the vertical dynamic stiffness index and bearing capacity of the cap-pile system in the similar formation environment. For the cap-pile system with four piles, the dynamic stiffness is about four times as large as the single pile between 10 and 20 Hz.

  14. Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions

    Science.gov (United States)

    Jung, HoHyun; Chun, Keyoung Jin; Hong, Jaesoo; Lim, Dohyung

    2015-01-01

    Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m2) were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior–posterior, right-diagonal, medial–lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P0.05). These results indicate that optimizing rotation control of the base plate of balance rehabilitation training equipment to induce anterior–posterior and medial–lateral dynamic rotation preferentially can lead to effective balance training. Additional tests with varied speeds and ranges of angles of base plate rotation are expected to be useful as well as an analysis of the balance characteristics considering a balance index that reflects the muscle activity and cooperative characteristics. PMID:26508847

  15. Analysis methods for fast impurity ion dynamics data

    International Nuclear Information System (INIS)

    Den Hartog, D.J.; Almagri, A.F.; Prager, S.C.; Fonck, R.J.

    1994-08-01

    A high resolution spectrometer has been developed and used on the MST reversed-field pinch (RFP) to measure passively impurity ion temperatures and flow velocities with 10 μs temporal resolution. Such measurements of MHD-scale fluctuations are particularly relevant in the RFP because the flow velocity fluctuation induced transport of current (the ''MHD dynamo'') may produce the magnetic field reversal characteristic of an RFP. This instrument will also be used to measure rapid changes in the equilibrium flow velocity, such as occur during locking and H-mode transition. The precision of measurements made to date is <0.6 km/s. The authors are developing accurate analysis techniques appropriate to the reduction of this fast ion dynamics data. Moment analysis and curve-fitting routines have been evaluated for noise sensitivity and robustness. Also presented is an analysis method which correctly separates the flux-surface average of the correlated fluctuations in u and B from the fluctuations due to rigid shifts of the plasma column

  16. Dynamic Analysis of Planar 3-RRR Flexible Parallel Robots with Dynamic Stiffening

    Directory of Open Access Journals (Sweden)

    Qinghua Zhang

    2014-01-01

    Full Text Available In consideration of the second-order coupling quantity of the axial displacement caused by the transverse displacement of flexible beam, the first-order approximation coupling model of planar 3-RRR flexible parallel robots is presented, in which the rigid body motion constraints, elastic deformation motion constraints, and dynamic constraints of the moving platform are considered. Based on the different speed of the moving platform, numerical simulation results using the conventional zero-order approximation coupling model and the proposed firstorder approximation coupling model show that the effect of “dynamic stiffening” term on dynamic characteristics of the system is insignificant and can be neglected, and the zero-order approximation coupling model is enough precisely for catching essentially dynamic characteristics of the system. Then, the commercial software ANSYS 13.0 is used to confirm the validity of the zero-order approximation coupling model.

  17. An analysis of depth dose characteristics of photon in water

    International Nuclear Information System (INIS)

    Buzdar, S.A.; Rao, M.A.; Nazir, A.

    2009-01-01

    Photon beam is most widely being used for radiation therapy. Biological effect of radiation is concerned with the evaluation of energy absorbed in the tissues. It was aimed to analyse the depth dose characteristics of x-ray beams of diverse energies to enhance the quality of radiotherapy treatment planning. Depth dose characteristics of different energy photon beams in water have been analysed. Photon beam is attenuated by the medium and the transmitted beam with less intensity causes lesser absorbed dose as depth increases. Relative attenuation on certain points on the beam axis and certain percentage of doses on different depths for available energies has been investigated. Photon beam depth dose characteristics do not show identical attributes as interaction of x-ray with matter is mainly governed by beam quality. Attenuation and penetration parameters of photon show variation with dosimetric parameters like field size due to scattering and Source to Surface Distance due to inverse square law, but the major parameter in photon interactions is its energy. Detailed analysis of photon Depth Dose characteristics helps to select appropriate beam for radiotherapy treatment when variety of beam energies available. Evaluation of this type of characteristics will help to establish theoretical relationships between dosimetric parameters to confirm measured values of dosimetric quantities, and hence to increase accuracy in radiotherapy treatment. (author)

  18. Soil dynamics and accelerated erosion: a sensitivity analysis of the LPJ Dynamic vegetation model

    Science.gov (United States)

    Bouchoms, Samuel; Van Oost, Kristof; Vanacker, Veerle; Kaplan, Jed O.; Vanwalleghem, Tom

    2013-04-01

    It is widely accepted that humans have become a major geomorphic force by disturbing natural vegetation patterns. Land conversion for agriculture purposes removes the protection of soils by the natural vegetation and leads to increased soil erosion by one to two orders of magnitude, breaking the balance that exists between the loss of soils and its production. Accelerated erosion and deposition have a strong influence on evolution and heterogeneity of basic soil characteristics (soil thickness, hydrology, horizon development,…) as well as on organic matter storage and cycling. Yet, since they are operating at a long time scale, those processes are not represented in state-of-art Dynamic Global Vegetation Models, which is a clear lack when exploring vegetation dynamics over past centuries. The main objectives of this paper are (i) to test the sensitivity of a Dynamic Global Vegetation Model, in terms of NPP and organic matter turnover, variations in state variables in response to accelerated erosion and (ii) to assess the performance of the model under the impact of erosion for a case-study in Central Spain. We evaluated the Lund-Postdam-Jena Dynamic Vegetation Model (LPJ DVGM) (Sitch et al, 2003) which simulates vegetation growth and carbon pools at the surface and in the soil based on climatic, pedologic and topographic variables. We assessed its reactions to changes in key soil properties that are affected by erosion such as texture and soil depth. We present the results of where we manipulated soil texture and bulk density while keeping the environmental drivers of climate, slope and altitude constant. For parameters exhibiting a strong control on NPP or SOM, a factorial analysis was conducted to test for interaction effects. The simulations show an important dependence on the clay content, especially for the slow cycling carbon pools and the biomass production, though the underground litter seems to be mostly influenced by the silt content. The fast cycling C

  19. Temperature control characteristics analysis of lead-cooled fast reactor with natural circulation

    International Nuclear Information System (INIS)

    Yang, Minghan; Song, Yong; Wang, Jianye; Xu, Peng; Zhang, Guangyu

    2016-01-01

    Highlights: • The LFR temperature control system are analyzed with frequency domain method. • The temperature control compensator is designed according to the frequency analysis. • Dynamic simulation is performed by SIMULINK and RELAP5-HD. - Abstract: Lead-cooled Fast Reactor (LFR) with natural circulation in primary system is among the highlights in advance nuclear reactor research, due to its great superiority in reactor safety and reliability. In this work, a transfer function matrix describing coolant temperature dynamic process, obtained by Laplace transform of the one-dimensional system dynamic model is developed in order to investigate the temperature control characteristics of LFR. Based on the transfer function matrix, a close-loop coolant temperature control system without compensator is built. The frequency domain analysis indicates that the stability and steady-state of the temperature control system needs to be improved. Accordingly, a temperature compensator based on Proportion–Integration and feed-forward is designed. The dynamic simulation of the whole system with the temperature compensator for core power step change is performed with SIMULINK and RELAP5-HD. The result shows that the temperature compensator can provide superior coolant temperature control capabilities in LFR with natural circulation due to the efficiency of the frequency domain analysis method.

  20. Comparison of different methods for the determination of dynamic characteristics of low velocity anemometers

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Popiolek, Z.

    2004-01-01

    Three methods for determining the dynamic characteristics of low velocity thermal anemometers were compared. They were: step-up velocity change and step-down velocity change methods and a method based on sinusoidal type velocity fluctuations. Two low velocity thermal anemometers with omnidirectio......Three methods for determining the dynamic characteristics of low velocity thermal anemometers were compared. They were: step-up velocity change and step-down velocity change methods and a method based on sinusoidal type velocity fluctuations. Two low velocity thermal anemometers...... with omnidirectional velocity sensors were tested. The results identify differences in frequency response of low velocity anemometers determined by the three methods. The time constant and the response time determined by the step-up velocity change method and the step-down velocity change method may be substantially...... different and insufficient for describing the frequency response of all low velocity thermal anemometers. Therefore the upper frequency, determined in tests with sinusoidal velocity fluctuations, is recommended to be used in indoor climate standards as a single parameter describing the dynamic...

  1. Correction of Dynamic Characteristics of SAR Cryogenic GTE on Consumption of Gasified Fuel

    Science.gov (United States)

    Bukin, V. A.; Gimadiev, A. G.; Gangisetty, G.

    2018-01-01

    When the gas turbine engines (GTE) NK-88 were developed for liquid hydrogen and NK-89 for liquefied natural gas, performance of the systems with a turbo-pump unitary was improved and its proved without direct regulation of the flow of a cryogenic fuel, which was supplied by a centrifugal pump of the turbo-pump unit (TPU) Command from the “kerosene” system. Such type of the automatic control system (SAR) has the property of partial “neutralization” of the delay caused by gasification of the fuel. This does not require any measurements in the cryogenic medium, and the failure of the centrifugal cryogenic pump does not lead to engine failure. On the other hand, the system without direct regulation of the flow of cryogenic fuel has complex internal dynamic connections, their properties are determined by the characteristics of the incoming units and assemblies, and it is difficult to maintain accurate the maximum boundary level and minimum fuel consumption due to the influence of a booster pressure change. Direct regulation of the consumption of cryogenic fuel (prior to its gasification) is the preferred solution, since for using traditional liquid and gaseous fuels this is the main and proven method. The scheme of correction of dynamic characteristics of a single-loop SAR GTE for the consumption of a liquefied cryogenic fuel with a flow rate correction in its gasified state, which ensures the dynamic properties of the system is not worse than for NK-88 and NK-89 engines.

  2. Study about the influence of cavitation on the dynamic characteristics for the sliding bearing

    International Nuclear Information System (INIS)

    Zhai, L M; Luo, Y Y; Wang, Z W

    2015-01-01

    Sliding bearings are employed to support the rotor system and limit the vibration amplitude. In high speed rotor system, cavitation often occurs in the oil film and affects the dynamic characteristics of the sliding bearing greatly. In this paper, numerical method is adopted to simulate the cavitation in the oil film with homogeneous two-phase mixture flow using Singhal-et-al cavitation model in the commercial code FLUENT-solver. Cases without cavitation model were also calculated at the same time. Many computations with different frequency ratios were conducted. Then the rotor dynamic characteristics of the sliding bearing were retrieved. The results show that the cavitation has great influences on the pressure distribution in the oil film. As the rotational speed or whirling speed of the journal increases, the cavitation will become prominent. The dynamic coefficients of the bearing such as stiffness and damping with cavitation model considered are quite different from that without cavitation. So it is worth to pay attention to and do further study about the cavitation in the sliding bearing in the high speed rotor system

  3. Experimental research of kinetic and dynamic characteristics of temperature movements of machines

    Science.gov (United States)

    Parfenov, I. V.; Polyakov, A. N.

    2018-03-01

    Nowadays, the urgency of informational support of machines at different stages of their life cycle is increasing in the form of various experimental characteristics that determine the criteria for working capacity. The effectiveness of forming the base of experimental characteristics of machines is related directly to the duration of their field tests. In this research, the authors consider a new technique that allows reducing the duration of full-scale testing of machines by 30%. To this end, three new indicator coefficients were calculated in real time to determine the moments corresponding to the characteristic points. In the work, new terms for thermal characteristics of machine tools are introduced: kinetic and dynamic characteristics of the temperature movements of the machine. This allow taking into account not only the experimental values for the temperature displacements of the elements of the carrier system of the machine, but also their derivatives up to the third order, inclusively. The work is based on experimental data obtained in the course of full-scale thermal tests of a drilling-milling and boring CNC machine.

  4. Dynamic analysis of rail vehicle axle

    Indian Academy of Sciences (India)

    In the study of Yagiz & Gursel (2005), the vertical and angular vibrations of the .... Figure 6. Variation of dynamic forces versus speed related to way conditions. ... analysed due to spring stiffness and railway quality and passenger coach load.

  5. Victim countries of transnational terrorism: an empirical characteristics analysis.

    Science.gov (United States)

    Elbakidze, Levan; Jin, Yanhong

    2012-12-01

    This study empirically investigates the association between country-level socioeconomic characteristics and risk of being victimized in transnational terrorism events. We find that a country's annual financial contribution to the U.N. general operating budget has a positive association with the frequency of being victimized in transnational terrorism events. In addition, per capita GDP, political freedom, and openness to trade are nonlinearly related to the frequency of being victimized in transnational terrorism events. © 2012 Society for Risk Analysis.

  6. EXPERIMENTAL ANALYSIS OF THE CHARACTERISTIC PERFORMANCE OF STANDALONE PHOTOVOLTAIC SYSTEM

    OpenAIRE

    Birendra Kishore; Anirban Nandy*; O.P. Pandey

    2016-01-01

    This paper demonstrates an insight solar PV Stand Alone system which is a practical model with a halogen light source. At different situations the performance of solar PV cells are analyzed. The system produces power with depending on the change in halogen light intensity & temperature. A theoretical & experimental analysis of the PV cell can be achieved. In this paper the I-V & P-V characteristic of the solar photovoltaic cells with changes in temperature and isolation have been showed. With...

  7. Dynamic Gust Load Analysis for Rotors

    Directory of Open Access Journals (Sweden)

    Yuting Dai

    2016-01-01

    Full Text Available Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.

  8. Analysis of the tuning characteristics of microwave plasma source

    Energy Technology Data Exchange (ETDEWEB)

    Miotk, Robert, E-mail: rmiotk@imp.gda.pl; Jasiński, Mariusz [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdańsk (Poland); Mizeraczyk, Jerzy [Department of Marine Electronics, Gdynia Maritime University, Morska 81-87, 81-225 Gdynia (Poland)

    2016-04-15

    In this paper, we present an analysis of the tuning characteristics of waveguide-supplied metal-cylinder-based nozzleless microwave plasma source. This analysis has enabled to estimate the electron concentration n{sub e} and electron frequency collisions ν in the plasma generated in nitrogen and in a mixture of nitrogen and ethanol vapour. The parameters n{sub e} and ν are the basic quantities that characterize the plasma. The presented new plasma diagnostic method is particularly useful, when spectroscopic methods are useless. The presented plasma source is currently used in research of a hydrogen production from liquids.

  9. Analysis of the tuning characteristics of microwave plasma source

    International Nuclear Information System (INIS)

    Miotk, Robert; Jasiński, Mariusz; Mizeraczyk, Jerzy

    2016-01-01

    In this paper, we present an analysis of the tuning characteristics of waveguide-supplied metal-cylinder-based nozzleless microwave plasma source. This analysis has enabled to estimate the electron concentration n_e and electron frequency collisions ν in the plasma generated in nitrogen and in a mixture of nitrogen and ethanol vapour. The parameters n_e and ν are the basic quantities that characterize the plasma. The presented new plasma diagnostic method is particularly useful, when spectroscopic methods are useless. The presented plasma source is currently used in research of a hydrogen production from liquids.

  10. Multivariate Analysis Of Ground Water Characteristics Of Geological Formations Of Enugu State Of Nigeria

    Directory of Open Access Journals (Sweden)

    Orakwe

    2015-08-01

    Full Text Available Abstract The chemometric data mining techniques using principal factor analysis PFA and hierarchical cluster analysis CA was employed to evaluate and to examine the borehole characteristics of geological formations of Enugu State of Nigeria to determine the latent structure of the borehole characteristics and to classify 9 borehole parameters from 49 locations into borehole groups of similar characteristics. PFA extracted three factors which accounted for a large proportion of the variation in the data 77.305 of the variance. Out of nine parameters examined the first PFA had the highest number of variables loading on a single factor where four borehole parameters borehole depth borehole casing static water level and dynamic water level loaded on it with positive coefficient as the most significant parameters responsible for variation in borehole characteristics in the study. The CA employed in this study to identified three clusters. The first cluster delineated stations that characterise Awgu sandstone geological formation while the second cluster delineated Agbani sandstone geological formation. The third cluster delineated Ajali sandstone formation. The CA grouping of the borehole parameters showed similar trend with PFA hence validating the efficiency of chemometric data mining techniques in grouping of variations in the borehole characteristics in the geological zone of the study area.

  11. Visibility graph analysis on heartbeat dynamics of meditation training

    Science.gov (United States)

    Jiang, Sen; Bian, Chunhua; Ning, Xinbao; Ma, Qianli D. Y.

    2013-06-01

    We apply the visibility graph analysis to human heartbeat dynamics by constructing the complex networks of heartbeat interval time series and investigating the statistical properties of the network before and during chi and yoga meditation. The experiment results show that visibility graph analysis can reveal the dynamical changes caused by meditation training manifested as regular heartbeat, which is closely related to the adjustment of autonomous neural system, and visibility graph analysis is effective to evaluate the effect of meditation.

  12. Discretization model for nonlinear dynamic analysis of three dimensional structures

    International Nuclear Information System (INIS)

    Hayashi, Y.

    1982-12-01

    A discretization model for nonlinear dynamic analysis of three dimensional structures is presented. The discretization is achieved through a three dimensional spring-mass system and the dynamic response obtained by direct integration of the equations of motion using central diferences. First the viability of the model is verified through the analysis of homogeneous linear structures and then its performance in the analysis of structures subjected to impulsive or impact loads, taking into account both geometrical and physical nonlinearities is evaluated. (Author) [pt

  13. Effects of carbon nanofiller characteristics on PTT chain conformation and dynamics: A computational study

    Energy Technology Data Exchange (ETDEWEB)

    Asadinezhad, Ahmad, E-mail: asadinezhad@cc.iut.ac.ir; Kelich, Payam

    2017-01-15

    Highlights: • Poly (trimethylene terephthalate) (PTT) conformation adopts a folded shape near nanofiller surface. • Graphene and carbon nanotube with different size and chemistry were simulated. • Graphene functionalization induces stronger confinement on PTT chain conformation. • PTT chain motion alters in dynamics mode as it becomes adsorbed onto nanofillers. • PTT reveals further changes near graphene than carbon nanotube surface. - Abstract: The effects of nanofiller chemistry and geometry on static and dynamic properties of an aromatic polyester, poly (trimethylene terephthalate), were addressed thanks to long-run classical molecular dynamics simulation. Two carbon nanofillers, graphene and carbon nanotube, were employed, where graphene was used in pristine and functionalized forms and carbon nanotube was used in two different diameters. The nanofiller geometry and chemistry were found to exert significant effects on conformation and dynamic behavior of PTT chain at the interface within the time scale the simulation was performed. It was found that PTT chain underwent interaction of van der Waals type with nanofiller via two subsequent phases, adsorption and orientation. The former stage, with definite characteristic time, involved translation of polymer chain toward interface while the latter was controlled by vibrational motions of chain atoms. The consequence of interaction was an increase in conformational order of polymer chain by transition to folded shape being favorable for any subsequent structural ordering (crystallization). The interaction of polymer with nanofiller gave rise to a reduction in overall mobility of polymer chain characterized by crossover from normal diffusive motion to subdiffusive mode.

  14. Effects of carbon nanofiller characteristics on PTT chain conformation and dynamics: A computational study

    International Nuclear Information System (INIS)

    Asadinezhad, Ahmad; Kelich, Payam

    2017-01-01

    Highlights: • Poly (trimethylene terephthalate) (PTT) conformation adopts a folded shape near nanofiller surface. • Graphene and carbon nanotube with different size and chemistry were simulated. • Graphene functionalization induces stronger confinement on PTT chain conformation. • PTT chain motion alters in dynamics mode as it becomes adsorbed onto nanofillers. • PTT reveals further changes near graphene than carbon nanotube surface. - Abstract: The effects of nanofiller chemistry and geometry on static and dynamic properties of an aromatic polyester, poly (trimethylene terephthalate), were addressed thanks to long-run classical molecular dynamics simulation. Two carbon nanofillers, graphene and carbon nanotube, were employed, where graphene was used in pristine and functionalized forms and carbon nanotube was used in two different diameters. The nanofiller geometry and chemistry were found to exert significant effects on conformation and dynamic behavior of PTT chain at the interface within the time scale the simulation was performed. It was found that PTT chain underwent interaction of van der Waals type with nanofiller via two subsequent phases, adsorption and orientation. The former stage, with definite characteristic time, involved translation of polymer chain toward interface while the latter was controlled by vibrational motions of chain atoms. The consequence of interaction was an increase in conformational order of polymer chain by transition to folded shape being favorable for any subsequent structural ordering (crystallization). The interaction of polymer with nanofiller gave rise to a reduction in overall mobility of polymer chain characterized by crossover from normal diffusive motion to subdiffusive mode.

  15. Using pressure square-like wave to measure the dynamic characteristics of piezoelectric pressure sensor

    International Nuclear Information System (INIS)

    Han, L-L; Tsung, T-T; Chen, L-C; Chang Ho; Jwo, C-S

    2005-01-01

    Piezoelectric pressure sensors are commonly used to measuring the dynamic characteristics in a hydraulic system. The dynamic measurements require a pressure sensor which has a high response rate. In this paper, we proposed use of a pressure square wave to excite the piezoelectric pressure sensor. Experimental frequencies are 0.5, 1.0, 1.5, and 2.0 kHz at 10, 15, 20 bar, respectively. Results show that the waveform of time-domain and frequencydomain response are quite different under above testing conditions. The higher the frequencies tested, the faster the pressure-rise speeds obtained. Similarly, the higher the testing pressure, the shorter the rise time attained

  16. Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing.

    Science.gov (United States)

    Liu, Ren; Wang, Xiao-Li; Zhang, Xiao-Qing

    2012-04-01

    The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that under the slip-flow regime, the decrease in the pressure and stiffness become obvious with the increasing of the compressibility number. Moreover, with the decrease of the relative gas-film-thickness, the deviations of dynamic coefficients between slip-flow-model and continuum-flow-model are increasing.

  17. Investigation of the dynamic characteristics of the hydro unit A in HPP Vrutok (Macedonia)

    International Nuclear Information System (INIS)

    Fushtikj, Vangel; Iliev, Atanas; Weber, H.; Prillwitz, F.; Kukoski, Ivan; Bekiri, Ejup

    2001-01-01

    Following up-to date technology for research, measurement, inspection and testing of the dynamical performances of the Electric Power System, the expert's teams from Faculty of Electrical Engineering - Skopje, University of Rostock and local experts from HPP's Vrutok, performed sets of experiments for identification of the dynamical, characteristics of the Unit A in HPP's Vrutok. Such experiments and examination are inevitable task for determining the possibilities of the units to operate in a new environment of deregulate market of electric energy, especially to operate on it's own network and to supply isolated consumers. In this paper, the method, the procedure, as well as, part of the obtained practical results are presented and discussed. (Original)

  18. Physicochemical characteristics and droplet impact dynamics of superhydrophobic carbon nanotube arrays.

    Science.gov (United States)

    Aria, Adrianus I; Gharib, Morteza

    2014-06-17

    The physicochemical and droplet impact dynamics of superhydrophobic carbon nanotube arrays are investigated. These superhydrophobic arrays are fabricated simply by exposing the as-grown carbon nanotube arrays to a vacuum annealing treatment at a moderate temperature. This treatment, which allows a significant removal of oxygen adsorbates, leads to a dramatic change in wettability of the arrays, from mildly hydrophobic to superhydrophobic. Such change in wettability is also accompanied by a substantial change in surface charge and electrochemical properties. Here, the droplet impact dynamics are characterized in terms of critical Weber number, coefficient of restitution, spreading factor, and contact time. Based on these characteristics, it is found that superhydrophobic carbon nanotube arrays are among the best water-repellent surfaces ever reported. The results presented herein may pave a way for the utilization of superhydrophobic carbon nanotube arrays in numerous industrial and practical applications, including inkjet printing, direct injection engines, steam turbines, and microelectronic fabrication.

  19. Parametric Analyses of Dynamic Characteristic of the Cable-Stayed Pedestrian Bridge

    Directory of Open Access Journals (Sweden)

    Pańtak Marek

    2017-12-01

    Full Text Available The paper presents characteristics of the structural system and results of dynamic field tests and numerical parametric analyses of three-span, two-pylon, cable-stayed pedestrian bridge with steel-concrete composite deck and spans of 25.5 + 60.0 + 25.5 m. The footbridge is characterized by increased dynamic susceptibility of the elements of the suspension system observed during the everyday operation of the structure. The analyses have shown that the high amplitude vibrations of the pylon back-stay cables change the parameters of the structural system and consequently change the value of the natural vibration frequencies of the structure. In the paper, the selection methodology of parameters of the computational model which allows to correctly determine the natural vibration frequencies of the footbridge has been presented.

  20. Guidelines for Computing Longitudinal Dynamic Stability Characteristics of a Subsonic Transport

    Science.gov (United States)

    Thompson, Joseph R.; Frank, Neal T.; Murphy, Patrick C.

    2010-01-01

    A systematic study is presented to guide the selection of a numerical solution strategy for URANS computation of a subsonic transport configuration undergoing simulated forced oscillation about its pitch axis. Forced oscillation is central to the prevalent wind tunnel methodology for quantifying aircraft dynamic stability derivatives from force and moment coefficients, which is the ultimate goal for the computational simulations. Extensive computations are performed that lead in key insights of the critical numerical parameters affecting solution convergence. A preliminary linear harmonic analysis is included to demonstrate the potential of extracting dynamic stability derivatives from computational solutions.

  1. Generator dynamics in aeroelastic analysis and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, T.J.; Hansen, M.H.; Iov, F.

    2003-05-01

    This report contains a description of a dynamic model for a doubly-fed induction generator implemented in the aeroelastic code HAWC. The model has physical input parameters (resistance, reactance etc.) and input variables (stator and rotor voltage and rotor speed). The model can be used to simulate the generator torque as well as the rotor and stator currents, active and reactive power. A perturbation method has been used to reduce the original generator model equations to a set of equations which can be solved with the same time steps as a typical aeroelastic code. The method is used to separate the fast transients of the model from the slow variations and deduce a reduced order expression for the slow part. Dynamic effects of the first order terms in the model as well as the influence on drive train eigenfrequencies and damping has been investigated. Load response during time simulation of wind turbine response have been compared to simulations with a linear static generator model originally implemented i HAWC. A 2 MW turbine has been modelled in the aeroelastic code HAWC. When using the new dynamic generator model there is an interesting coupling between the generator dynamics and a global turbine vibration mode at 4.5 Hz, which only occurs when a dynamic formulation of the generator equations is applied. This frequency can especially be seen in the electrical power of the generator and the rotational speed of the generator, but also as torque variations in the drive train. (au)

  2. Adjoint sensitivity analysis of dynamic reliability models based on Markov chains - I: Theory

    International Nuclear Information System (INIS)

    Cacuci, D. G.; Cacuci, D. G.; Ionescu-Bujor, M.

    2008-01-01

    The development of the adjoint sensitivity analysis procedure (ASAP) for generic dynamic reliability models based on Markov chains is presented, together with applications of this procedure to the analysis of several systems of increasing complexity. The general theory is presented in Part I of this work and is accompanied by a paradigm application to the dynamic reliability analysis of a simple binary component, namely a pump functioning on an 'up/down' cycle until it fails irreparably. This paradigm example admits a closed form analytical solution, which permits a clear illustration of the main characteristics of the ASAP for Markov chains. In particular, it is shown that the ASAP for Markov chains presents outstanding computational advantages over other procedures currently in use for sensitivity and uncertainty analysis of the dynamic reliability of large-scale systems. This conclusion is further underscored by the large-scale applications presented in Part II. (authors)

  3. Adjoint sensitivity analysis of dynamic reliability models based on Markov chains - I: Theory

    Energy Technology Data Exchange (ETDEWEB)

    Cacuci, D. G. [Commiss Energy Atom, Direct Energy Nucl, Saclay, (France); Cacuci, D. G. [Univ Karlsruhe, Inst Nucl Technol and Reactor Safety, D-76021 Karlsruhe, (Germany); Ionescu-Bujor, M. [Forschungszentrum Karlsruhe, Fus Program, D-76021 Karlsruhe, (Germany)

    2008-07-01

    The development of the adjoint sensitivity analysis procedure (ASAP) for generic dynamic reliability models based on Markov chains is presented, together with applications of this procedure to the analysis of several systems of increasing complexity. The general theory is presented in Part I of this work and is accompanied by a paradigm application to the dynamic reliability analysis of a simple binary component, namely a pump functioning on an 'up/down' cycle until it fails irreparably. This paradigm example admits a closed form analytical solution, which permits a clear illustration of the main characteristics of the ASAP for Markov chains. In particular, it is shown that the ASAP for Markov chains presents outstanding computational advantages over other procedures currently in use for sensitivity and uncertainty analysis of the dynamic reliability of large-scale systems. This conclusion is further underscored by the large-scale applications presented in Part II. (authors)

  4. Inferring gene expression dynamics via functional regression analysis

    Directory of Open Access Journals (Sweden)

    Leng Xiaoyan

    2008-01-01

    Full Text Available Abstract Background Temporal gene expression profiles characterize the time-dynamics of expression of specific genes and are increasingly collected in current gene expression experiments. In the analysis of experiments where gene expression is obtained over the life cycle, it is of interest to relate temporal patterns of gene expression associated with different developmental stages to each other to study patterns of long-term developmental gene regulation. We use tools from functional data analysis to study dynamic changes by relating temporal gene expression profiles of different developmental stages to each other. Results We demonstrate that functional regression methodology can pinpoint relationships that exist between temporary gene expression profiles for different life cycle phases and incorporates dimension reduction as needed for these high-dimensional data. By applying these tools, gene expression profiles for pupa and adult phases are found to be strongly related to the profiles of the same genes obtained during the embryo phase. Moreover, one can distinguish between gene groups that exhibit relationships with positive and others with negative associations between later life and embryonal expression profiles. Specifically, we find a positive relationship in expression for muscle development related genes, and a negative relationship for strictly maternal genes for Drosophila, using temporal gene expression profiles. Conclusion Our findings point to specific reactivation patterns of gene expression during the Drosophila life cycle which differ in characteristic ways between various gene groups. Functional regression emerges as a useful tool for relating gene expression patterns from different developmental stages, and avoids the problems with large numbers of parameters and multiple testing that affect alternative approaches.

  5. Universal shape characteristics for the mesoscopic star-shaped polymer via dissipative particle dynamics simulations

    Science.gov (United States)

    Kalyuzhnyi, O.; Ilnytskyi, J. M.; Holovatch, Yu; von Ferber, C.

    2018-05-01

    In this paper we study the shape characteristics of star-like polymers in various solvent quality using a mesoscopic level of modeling. The dissipative particle dynamics simulations are performed for the homogeneous and four different heterogeneous star polymers with the same molecular weight. We analyse the gyration radius and asphericity at the poor, good and θ-solvent regimes. Detailed explanation based on interplay between enthalpic and entropic contributions to the free energy and analyses on of the asphericity of individual branches are provided to explain the increase of the apsphericity in θ-solvent regime.

  6. On interrelation of crack resistance characteristics of metal materials under static and dynamic loading conditions

    International Nuclear Information System (INIS)

    Abramyan, K.G.; Goloveshkin, Yu.V.; Tuzlukova, N.I.

    1984-01-01

    Home and foreign data on crack resistance characteristics of metal structural materials are generalized and analyzed. Dependence between various parameters of material strength and toughness on the one hand and racck resistance on the other hand is established on the basis of the energy concept of the failure mechanics. Effect of the strain rate on σsub(0.2) and Ksub(Ic) values is evaluated. Quanlitative and quantitative relations obtained permit conducting a complex estimation of materials behaviour during static and dynamic loading operations

  7. Analysis of Handling Qualities Design Criteria for Active Inceptor Force-Feel Characteristics

    Science.gov (United States)

    Malpica, Carlos A.; Lusardi, Jeff A.

    2013-01-01

    The force-feel system characteristics of the cyclic inceptors of most helicopters are set based on the characteristics of the mechanical components in the control system (mass, springs, friction dampers, etc.). For these helicopters, the force-feel characteristics typically remain constant over the entire flight envelope, with perhaps a trim release to minimize control forces while maneuvering. With the advent of fly-by-wire control systems and active inceptors in helicopters, the force-feel characteristics are now determined by the closed-loop response of the active inceptor itself as defined by the inertia, force/displacement gradient, damping, breakout force and detent shape configuration parameters in the inceptor control laws. These systems give the flexibility to dynamically prescribe different feel characteristics for different control modes or flight conditions, and the ability to provide tactile cueing to the pilot through the actively controlled side-stick or center-stick cyclic inceptor. For rotorcraft, a few studies have been conducted to assess the effects of cyclic force-feel characteristics on handling qualities in flight. An early study provided valuable insight into the static force-deflection characteristics (force gradient) and the number of axes controlled by the side-stick controller for the U.S. Army's Advanced Digital/Optical Control System (ADOCS) demonstrator aircraft [1]. The first of a series of studies providing insight on the inceptor dynamic force-feel characteristics was conducted on the NASA/Army CH-47B variable-stability helicopter [2]. This work led to a proposed requirement that set boundaries based on the cyclic natural frequency and inertia, with the stipulation of a lower damping ratio limit of 0.3 [3]. A second study was conducted by the Canadian Institute for Aerospace Research using their variable-stability Bell 205A helicopter [4]. This research suggested boundaries for stick dynamics based on natural frequency and damping

  8. Measuring the Dynamic Characteristics of a Low Specific Speed Pump—Turbine Model

    Directory of Open Access Journals (Sweden)

    Eve Cathrin Walseth

    2016-03-01

    Full Text Available This paper presents results from an experiment performed to obtain the dynamic characteristics of a reversible pump-turbine model. The characteristics were measured in an open loop system where the turbine initially was run on low rotational speed before the generator was disconnected allowing the turbine to go towards runaway. The measurements show that the turbine experience damped oscillations in pressure, speed and flow rate around runaway corresponding with presented stability criterion in published literature. Results from the experiment is reproduced by means of transient simulations. A one dimensional analytical turbine model for representation of the pump-turbine is used in the calculations. The simulations show that it is possible to reproduce the physics in the measurement by using a simple analytical model for the pump-turbine as long as the inertia of the water masses in the turbine are modeled correctly.

  9. Supply circuit for and dynamic characteristics of discharge in a nitrogen laser

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, Yu L; Sukhanov, A N

    1978-03-01

    The dynamic characteristics of discharge in a nitrogen laser with an output radiation power at the 1 MW level were measured in an experiment under pressures ranging from 30 to 350 mm Hg. At the same time, the design and the performance of a supply circuit on the basis of a Blumlein line as pumping source were evaluated. The results of this study indicate that the practically attainable efficiency, which depends on the characteristics impedance of the discharge circuit, can be increased from 0.07 to 0.1% with a two-stage laser, by shortening the pump discharge and supplying most energy to the second stage at higher E/p ratios. Multistage high-power lasers operating in the generator-amplifier mode with high gain in the active medium are thus feasible without the need for expensive optical decoupling of stages.

  10. Analysis of Team Communication Characteristics Using SNA Technique

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ar Ryum; Lee, Seung Woo; Kang, Hyun Gook; Seong, Poong Hyun [KAIST, Daejeon (Korea, Republic of); Park, Jin Kyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-10-15

    An important aspect of human behavior in nuclear power plants (NPPs) is team interaction since operating NPPs involves the coordination of several team members among and within workplaces. In this environment, operators in NPPs communicate with each other to share situational information. Unfortunately, inappropriate communication can cause a lack of situational information and lead to serious consequences of systems. This implies that it is requisite to study the communication characteristics of operating team to secure the safety of NPPs. Many researchers have endeavored to investigate the characteristics of team communications. However, previous studies seem to characterize team communications based on a single perspective such as communication contents as well as communication structure. In this regard, it seems that social network analysis (SNA) would be a comprehensive method which enables analysts to characterize team communications from both perspectives. In this study, a density score which is one of the communication characteristics was obtained by using SNA. Moreover, the ratio of inappropriate communications was calculated using the taxonomy for inappropriate communication. Finally, the communication characteristic distinguished by the density score is compared with the ratio of inappropriate communications to extract meaningful insights which could contribute to prevent the occurrence of inappropriate communications

  11. Analysis of Team Communication Characteristics Using SNA Technique

    International Nuclear Information System (INIS)

    Kim, Ar Ryum; Lee, Seung Woo; Kang, Hyun Gook; Seong, Poong Hyun; Park, Jin Kyun

    2011-01-01

    An important aspect of human behavior in nuclear power plants (NPPs) is team interaction since operating NPPs involves the coordination of several team members among and within workplaces. In this environment, operators in NPPs communicate with each other to share situational information. Unfortunately, inappropriate communication can cause a lack of situational information and lead to serious consequences of systems. This implies that it is requisite to study the communication characteristics of operating team to secure the safety of NPPs. Many researchers have endeavored to investigate the characteristics of team communications. However, previous studies seem to characterize team communications based on a single perspective such as communication contents as well as communication structure. In this regard, it seems that social network analysis (SNA) would be a comprehensive method which enables analysts to characterize team communications from both perspectives. In this study, a density score which is one of the communication characteristics was obtained by using SNA. Moreover, the ratio of inappropriate communications was calculated using the taxonomy for inappropriate communication. Finally, the communication characteristic distinguished by the density score is compared with the ratio of inappropriate communications to extract meaningful insights which could contribute to prevent the occurrence of inappropriate communications

  12. Conformation analysis of trehalose. Molecular dynamics simulation and molecular mechanics

    International Nuclear Information System (INIS)

    Donnamaira, M.C.; Howard, E.I.; Grigera, J.R.

    1992-09-01

    Conformational analysis of the disaccharide trehalose is done by molecular dynamics and molecular mechanics. In spite of the different force fields used in each case, comparison between the molecular dynamics trajectories of the torsional angles of glycosidic linkage and energy conformational map shows a good agreement between both methods. By molecular dynamics it is observed a moderate mobility of the glycosidic linkage. The demands of computer time is comparable in both cases. (author). 6 refs, 4 figs

  13. Advances in analysis and control of timedelayed dynamical systems

    CERN Document Server

    Sun, Jianqiao

    2013-01-01

    Analysis and control of timedelayed systems have been applied in a wide range of applications, ranging from mechanical, control, economic, to biological systems. Over the years, there has been a steady stream of interest in timedelayed dynamic systems, this book takes a snap shot of recent research from the world leading experts in analysis and control of dynamic systems with time delay to provide a bird's eye view of its development. The topics covered in this book include solution methods, stability analysis and control of periodic dynamic systems with time delay, bifurcations, stochastic dy

  14. Incremental Centrality Algorithms for Dynamic Network Analysis

    Science.gov (United States)

    2013-08-01

    literature.   7.1.3 Small World Networks In 1998, Watts and Strogatz introduced a model that starts with a regular lattice (ring) of n nodes and...and S. Strogatz , "Collective Dynamics of ‘Small-World’ Networks," Nature, vol. 393, pp. 440-442, 1998. [13] T. Opsahl, "Structure and Evolution of...34On Random Graphs," Publicationes Mathematicae, vol. 6, 1959. [167] D.J. Watts and S.H. Strogatz , "Collective Dynamics of ‘Small-World’ Networks

  15. Failure behavior / characteristics of fabric reinforced polymer matrix composite and aluminum6061 on dynamic tensile loading

    International Nuclear Information System (INIS)

    Bang, Hyejin; Cho, Chongdu

    2017-01-01

    Composite materials are composed of multiple types of materials as reinforcement and matrix. Among them, CFRP (Carbon fiber reinforced polymer) is widely used materials in automotive and defense industry. Carbon fibers are used as a reinforcement, of which Young's modulus is in a prepreg form. In automotive industry, especially, high strain rate test is needed to measure dynamic properties, used in dynamic analysis like high inertia included simulation as a car crash. In this paper, a SHTB (Split Hopkinson tensile bar) machine is employed for estimating stress-strain curve under dynamic load condition on aluminum 6061 and CFRP. The strain rate range is about from 100 /s to 1000 /s and the number of prepreg layers of composite specimen is total eight plies which are stacked symmetrically to structure CFRP. As a result, stress / strain point data are obtained and used for simulation into stacked composites.

  16. Failure behavior / characteristics of fabric reinforced polymer matrix composite and aluminum6061 on dynamic tensile loading

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Hyejin; Cho, Chongdu [Inha University, Incheon (Korea, Republic of)

    2017-08-15

    Composite materials are composed of multiple types of materials as reinforcement and matrix. Among them, CFRP (Carbon fiber reinforced polymer) is widely used materials in automotive and defense industry. Carbon fibers are used as a reinforcement, of which Young's modulus is in a prepreg form. In automotive industry, especially, high strain rate test is needed to measure dynamic properties, used in dynamic analysis like high inertia included simulation as a car crash. In this paper, a SHTB (Split Hopkinson tensile bar) machine is employed for estimating stress-strain curve under dynamic load condition on aluminum 6061 and CFRP. The strain rate range is about from 100 /s to 1000 /s and the number of prepreg layers of composite specimen is total eight plies which are stacked symmetrically to structure CFRP. As a result, stress / strain point data are obtained and used for simulation into stacked composites.

  17. the use of the dynamic magnification factor in the dynamic analysis

    African Journals Online (AJOL)

    Uncle Greg 4 Real

    bridges and some country's codes of practice made specifications in respect of the dynamic magnification factor for the analysis and design of various types of structures subjected to ... span. For example the United kingdom code. [10] presented dynamic magnification factors, related ... For SDOF (Single Degree of Freedom).

  18. Geometric analysis of nondeterminacy in dynamical systems

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Raussen, Martin Hubert

    2007-01-01

    This article intends to provide some new insights into concurrency using ideas from the theory of dynamical systems. Inherently discrete concurrency corresponds to a parallel continuous concept: a discrete state space corresponds to a differential manifold, an execution path corresponds to a flow...

  19. NPV Sensitivity Analysis: A Dynamic Excel Approach

    Science.gov (United States)

    Mangiero, George A.; Kraten, Michael

    2017-01-01

    Financial analysts generally create static formulas for the computation of NPV. When they do so, however, it is not readily apparent how sensitive the value of NPV is to changes in multiple interdependent and interrelated variables. It is the aim of this paper to analyze this variability by employing a dynamic, visually graphic presentation using…

  20. Analysis of Population Dynamics in World Economy

    OpenAIRE

    Martin, Gress

    2011-01-01

    Population dynamics is an important topic in current world economy. The size and growth of population have an impact on economic growth and development of individual countries and vice versa, economic development influences demographic variables in a country. The aim of the article is to analyze historical development of world population, population stock change and relations between population stock change and economic development.

  1. Likelihood-based Dynamic Factor Analysis for Measurement and Forecasting

    NARCIS (Netherlands)

    Jungbacker, B.M.J.P.; Koopman, S.J.

    2015-01-01

    We present new results for the likelihood-based analysis of the dynamic factor model. The latent factors are modelled by linear dynamic stochastic processes. The idiosyncratic disturbance series are specified as autoregressive processes with mutually correlated innovations. The new results lead to

  2. ANALYSIS AND OPTIMISATION OF DYNAMIC STABILITY OF MOBILE WORKING MACHINES

    Directory of Open Access Journals (Sweden)

    Peter BIGOŠ

    2014-09-01

    Full Text Available This paper describes an investigation of the dynamic stability, which is specified for the mobile working machines. There are presented the basic theoretical principles of the stability theory together with an introduction of two illustrative examples of the dynamic stability analysis.

  3. Computer Programme for the Dynamic Analysis of Tall Regular ...

    African Journals Online (AJOL)

    The traditional method of dynamic analysis of tall rigid frames assumes the shear frame model. Models that allow joint rotations with/without the inclusion of the column axial loads give improved results but pose much more computational difficulty. In this work a computer program Natfrequency that determines the dynamic ...

  4. Effects of structural and dynamic family characteristics on the development of depressive and aggressive problems during adolescence. The TRAILS study

    NARCIS (Netherlands)

    Sijtsema, J.J.; Oldehinkel, A.J.; Veenstra, R.; Verhulst, F.C.; Ormel, J.

    2014-01-01

    Both structural (i.e., SES, familial psychopathology, family composition) and dynamic (i.e., parental warmth and rejection) family characteristics have been associated with aggressive and depressive problem development. However, it is unclear to what extent (changes in) dynamic family

  5. Effects of structural and dynamic family characteristics on the development of depressive and aggressive problems during adolescence. The TRAILS study

    NARCIS (Netherlands)

    Sijtsema, J. J.; Oldehinkel, A. J.; Veenstra, René; Verhulst, F. C.; Ormel, J.

    Both structural (i.e., SES, familial psychopathology, family composition) and dynamic (i.e., parental warmth and rejection) family characteristics have been associated with aggressive and depressive problem development. However, it is unclear to what extent (changes in) dynamic family

  6. Dynamical characteristics of an electromagnetic field under conditions of total reflection

    Science.gov (United States)

    Bekshaev, Aleksandr Ya

    2018-04-01

    The dynamical characteristics of electromagnetic fields include energy, momentum, angular momentum (spin) and helicity. We analyze their spatial distributions near the planar interface between two transparent and non-dispersive media, when the incident monochromatic plane wave with arbitrary polarization is totally reflected, and an evanescent wave is formed in the medium with lower optical density. Based on the recent arguments in favor of the Minkowski definition of the electromagnetic momentum in a material medium (Philbin 2011 Phys. Rev. A 83 013823; Philbin and Allanson 2012 86 055802; Bliokh et al 2017 Phys. Rev. Lett. 119 073901), we derive the explicit expressions for the dynamical characteristics in both media, with special attention to their behavior at the interface. In particular, the ‘extraordinary’ spin and momentum components orthogonal to the plane of incidence are described, and a canonical (spin-orbital) momentum decomposition is performed that contains no singular terms. The field energy, helicity, the spin momentum and orbital momentum components are everywhere regular but experience discontinuities at the interface; the spin components parallel to the interface appear to be continuous, which testifies to the consistency of the adopted Minkowski picture. The results supply a meaningful example of the electromagnetic momentum decomposition, with separation of spatial and polarization degrees of freedom, in inhomogeneous media, and can be used in engineering the structured fields designed for optical sorting, dispatching and micromanipulation.

  7. Numerical investigation of refrigeration machine compressor operation considering single-phase electric motor dynamic characteristics

    Science.gov (United States)

    Baidak, Y.; Smyk, V.

    2017-08-01

    Using as the base the differential equations system which was presented in relative units for generalized electric motor of hermetic refrigeration compressor, mathematical model of the software for dynamic performance calculation of refrigeration machine compressors drive low-power asynchronous motors was developed. Performed on its ground calculations of the basic model of two-phase electric motor drive of hermetic compressor and the proposed newly developed model of the motor with single-phase stator winding, which is an alternative to the industrial motor winding, have confirmed the benefits of the motor with innovative stator winding over the base engine. Given calculations of the dynamic characteristics of compressor drive motor have permitted to determine the value of electromagnetic torque swinging for coordinating compressor and motor mechanical characteristics, and for taking them into consideration in choosing compressor elements construction materials. Developed and used in the process of investigation of refrigeration compressor drive asynchronous single-phase motor mathematical and software can be considered as an element of computer-aided design system for design of the aggregate of refrigeration compression unit refrigerating machine.

  8. The dynamic characteristics of harvesting energy from mechanical vibration via piezoelectric conversion

    International Nuclear Information System (INIS)

    Fan Kang-Qi; Ming Zheng-Feng; Xu Chun-Hui; Chao Feng-Bo

    2013-01-01

    As an alternative power solution for low-power devices, harvesting energy from the ambient mechanical vibration has received increasing research interest in recent years. In this paper we study the transient dynamic characteristics of a piezoelectric energy harvesting system including a piezoelectric energy harvester, a bridge rectifier, and a storage capacitor. To accomplish this, this energy harvesting system is modeled, and the charging process of the storage capacitor is investigated by employing the in-phase assumption. The results indicate that the charging voltage across the storage capacitor and the gathered power increase gradually as the charging process proceeds, whereas the charging rate slows down over time as the charging voltage approaches to the peak value of the piezoelectric voltage across the piezoelectric materials. In addition, due to the added electrical damping and the change of the system natural frequency when the charging process is initiated, a sudden drop in the vibration amplitude is observed, which in turn affects the charging rate. However, the vibration amplitude begins to increase as the charging process continues, which is caused by the decrease in the electrical damping (i.e., the decrease in the energy removed from the mechanical vibration). This electromechanical coupling characteristic is also revealed by the variation of the vibration amplitude with the charging voltage. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  9. Dynamic Characteristics and Experimental Research of Dual-Rotor System with Rub-Impact Fault

    Directory of Open Access Journals (Sweden)

    Hongzhi Xu

    2016-01-01

    Full Text Available Rub-impact fault model for dual-rotor system was further developed, in which rubbing board is regarded as elastic sheet. Sheet elastic deformation, contact penetration, and elastic damping support during rubbing of sheet and wheel disk were considered. Collision force and friction were calculated by utilizing Hertz contact theory and Coulomb model and introducing nonlinear spring damping model and friction coefficient. Then kinetic differential equations of rub-impact under dry rubbing condition were established. Based on one-dimensional finite element model of dual-rotor system, dynamic transient response of overall structure under rub-impact existing between rotor wheel and sheet was obtained. Meanwhile, fault dynamic characteristics and impact of rubbing clearance on rotor vibration were analyzed. The results show that, during the process of rub-impact, the spectrums of rotor vibration are complicated and multiple combined frequency components of inner and outer rotor fundamental frequencies are typical characteristic of rub-impact fault for dual-rotor system. It also can be seen from rotor vibration response that the rubbing rotor’s fundamental frequency is modulated by normal rotor double frequency.

  10. Assessing Spatiotemporal Characteristics of Urbanization Dynamics in Southeast Asia Using Time Series of DMSP/OLS Nighttime Light Data

    Directory of Open Access Journals (Sweden)

    Min Zhao

    2018-01-01

    Full Text Available Intraregional spatial variations of satellite-derived anthropogenic nighttime light signals are gradually applied to identify different lighting areas with various socioeconomic activity and urbanization levels when characterizing urbanization dynamics. However, most previous partitioning approaches are carried out at local scales, easily leading to multi-standards of the extracted results from local areas, and this inevitably hinders the comparative analysis on the urbanization dynamics of the large region. Therefore, a partitioning approach considering the characteristics of nighttime light signals at both local and regional scales is necessary for studying spatiotemporal characteristics of urbanization dynamics across the large region using nighttime light imagery. Based on the quadratic relationships between the pixel-level nighttime light brightness and the corresponding spatial gradient for individual cities, we here proposed an improved partitioning approach to quickly identify different types of nighttime lighting areas for the entire region of Southeast Asia. Using the calibrated Defense Meteorological Satellite Program/Operational Line-scan System (DMSP/OLS data with greater comparability, continuity, and intra-urban variability, the annual nighttime light imagery spanning years 1992–2013 were divided into four types of nighttime lighting areas: low, medium, high, and extremely high, associated with different intensity of anthropogenic activity. The results suggest that Southeast Asia has experienced a rapid and diverse urbanization process from 1992 to 2013. Areas with moderate or low anthropogenic activity show a faster growth rate for the spatial expansion than the developed areas with intense anthropogenic activity. Transitions between different nighttime lighting types potentially depict the trajectory of urban development, the darker areas are gradually transitioning to areas with higher lighting, indicating conspicuous trends

  11. Analysis and Optimization of Dynamic Measurement Precision of Fiber Optic Gyroscope

    Directory of Open Access Journals (Sweden)

    Hui Li

    2013-01-01

    Full Text Available In order to improve the dynamic performance of high precision interferometer fiber optic gyroscope (IFOG, the influencing factors of the fast response characteristics are analyzed based on a proposed assistant design setup, and a high dynamic detection method is proposed to suppress the adverse effects of the key influencing factors. The assistant design platform is built by using the virtual instrument technology for IFOG, which can monitor the closed-loop state variables in real time for analyzing the influence of both the optical components and detection circuit on the dynamic performance of IFOG. The analysis results indicate that nonlinearity of optical Sagnac effect, optical parameter uncertainty, dynamic characteristics of internal modules and time delay of signal detection circuit are the major causes of dynamic performance deterioration, which can induce potential system instability in practical control systems. By taking all these factors into consideration, we design a robust control algorithm to realize the high dynamic closed-loop detection of IFOG. Finally, experiments show that the improved 0.01 deg/h high precision IFOG with the proposed control algorithm can achieve fast tracking and good dynamic measurement precision.

  12. Integrating atomistic molecular dynamics simulations, experiments and network analysis to study protein dynamics: strength in unity

    Directory of Open Access Journals (Sweden)

    Elena ePapaleo

    2015-05-01

    Full Text Available In the last years, we have been observing remarkable improvements in the field of protein dynamics. Indeed, we can now study protein dynamics in atomistic details over several timescales with a rich portfolio of experimental and computational techniques. On one side, this provides us with the possibility to validate simulation methods and physical models against a broad range of experimental observables. On the other side, it also allows a complementary and comprehensive view on protein structure and dynamics. What is needed now is a better understanding of the link between the dynamic properties that we observe and the functional properties of these important cellular machines. To make progresses in this direction, we need to improve the physical models used to describe proteins and solvent in molecular dynamics, as well as to strengthen the integration of experiments and simulations to overcome their own limitations. Moreover, now that we have the means to study protein dynamics in great details, we need new tools to understand the information embedded in the protein ensembles and in their dynamic signature. With this aim in mind, we should enrich the current tools for analysis of biomolecular simulations with attention to the effects that can be propagated over long distances and are often associated to important biological functions. In this context, approaches inspired by network analysis can make an important contribution to the analysis of molecular dynamics simulations.

  13. Backyard housing in Gauteng: An analysis of spatial dynamics

    African Journals Online (AJOL)

    Backyard housing in Gauteng: An analysis of spatial dynamics. Yasmin Shapurjee ... Drawing on quantitative geo-demographic data from GeoTerraImage (GTI). (2010), Knowledge .... a fundamental role in absorbing demand for low-income ...

  14. The dynamic analysis of drum roll lathe for machining of rollers

    Science.gov (United States)

    Qiao, Zheng; Wu, Dongxu; Wang, Bo; Li, Guo; Wang, Huiming; Ding, Fei

    2014-08-01

    An ultra-precision machine tool for machining of the roller has been designed and assembled, and due to the obvious impact which dynamic characteristic of machine tool has on the quality of microstructures on the roller surface, the dynamic characteristic of the existing machine tool is analyzed in this paper, so is the influence of circumstance that a large scale and slender roller is fixed in the machine on dynamic characteristic of the machine tool. At first, finite element model of the machine tool is built and simplified, and based on that, the paper carries on with the finite element mode analysis and gets the natural frequency and shaking type of four steps of the machine tool. According to the above model analysis results, the weak stiffness systems of machine tool can be further improved and the reasonable bandwidth of control system of the machine tool can be designed. In the end, considering the shock which is caused by Z axis as a result of fast positioning frequently to feeding system and cutting tool, transient analysis is conducted by means of ANSYS analysis in this paper. Based on the results of transient analysis, the vibration regularity of key components of machine tool and its impact on cutting process are explored respectively.

  15. RADYBAN: A tool for reliability analysis of dynamic fault trees through conversion into dynamic Bayesian networks

    International Nuclear Information System (INIS)

    Montani, S.; Portinale, L.; Bobbio, A.; Codetta-Raiteri, D.

    2008-01-01

    In this paper, we present RADYBAN (Reliability Analysis with DYnamic BAyesian Networks), a software tool which allows to analyze a dynamic fault tree relying on its conversion into a dynamic Bayesian network. The tool implements a modular algorithm for automatically translating a dynamic fault tree into the corresponding dynamic Bayesian network and exploits classical algorithms for the inference on dynamic Bayesian networks, in order to compute reliability measures. After having described the basic features of the tool, we show how it operates on a real world example and we compare the unreliability results it generates with those returned by other methodologies, in order to verify the correctness and the consistency of the results obtained

  16. Dynamic response characteristics of the high-temperature superconducting maglev system under lateral eccentric distance

    Science.gov (United States)

    Wang, Bo; Zheng, Jun; Si, Shuaishuai; Qian, Nan; Li, Haitao; Li, Jipeng; Deng, Zigang

    2016-07-01

    Off-centre operation of high-temperature superconducting (HTS) maglev systems caused by inevitable conditions such as the misregistration of vehicle, crosswind and curve negotiation, may change the distribution of the trapped flux in the HTS bulks and the magnetic interaction between HTS bulks and the PMG. It impacts on the performance of HTS maglev, and more seriously makes the maglev vehicle overturned. Therefore, understanding the performance of the HTS maglev in off-center operation is very important. In this paper, the dynamic response characteristics of a cryostat with twenty-four onboard YBaCuO superconductor bulks were experimentally investigated at different eccentric distances under loads before the initial FC process. Parameters such as vibration accelerations, displacement, natural frequency and dynamic stiffness were acquired and analyzed via the B&K vibration analyzer and laser displacement sensors. Results suggest that the natural frequency and dynamic stiffness of the maglev vehicle would be obviously reduced with the eccentric distance, posing negative effects on the stability of HTS maglev.

  17. Evaporation characteristics of thin film liquid argon in nano-scale confinement: A molecular dynamics study

    Science.gov (United States)

    Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    Molecular dynamics simulation has been carried out to explore the evaporation characteristics of thin liquid argon film in nano-scale confinement. The present study has been conducted to realize the nano-scale physics of simultaneous evaporation and condensation inside a confined space for a three phase system with particular emphasis on the effect of surface wetting conditions. The simulation domain consisted of two parallel platinum plates; one at the top and another at the bottom. The fluid comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the domain. Considering hydrophilic and hydrophobic nature of top and bottom surfaces, two different cases have been investigated: (i) Case A: Both top and bottom surfaces are hydrophilic, (ii) Case B: both top and bottom surfaces are hydrophobic. For all cases, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall was set to four different temperatures such as 110 K, 120 K, 130 K and 140 K to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat fluxes normal to top and bottom walls were estimated and discussed to illuminate the effectiveness of heat transfer in both hydrophilic and hydrophobic confinement at various boundary temperatures of the bottom plate.

  18. Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

    Science.gov (United States)

    Liu, Feifei; Lan, Fengchong; Chen, Jiqing

    2016-07-01

    Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a ;segmented; thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed ;segmented; model shows more precise than the ;non-segmented; model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the ;segmented; model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

  19. Design of rotating mirror for ultra-high speed camera based on dynamic characteristic

    International Nuclear Information System (INIS)

    Li Chunbo; Chai Jinlong; Liang Yexing; Liu Chunping; Wang Hongzhi; Yu Chunhui; Li Jingzhen; Huang Hongbin

    2011-01-01

    A systematic design method has been proposed for studying the dynamic design of rotating mirror for ultra-high speed camera. With the finite element software, the numerical analyses of static, modal, harmonic responses and natural frequency sensitivity for the preliminary-designed rotating mirror were done based on the static and dynamic theories. Some experiments were done to verify the results. The physical dimensions of the rotating mirror were modified repeatedly according to the results for designing a new rotating mirror. Then simulation and experiments of fatigue life for the new rotating mirror under alternating force were done. The results show that the maximum static stress is less than the yield stress of the rotating mirror material, which proves the new rotating mirror will not be subjected to static strength failure. However, the results of modal and harmonic response analyses indicate that the dynamic characteristic of the new rotating mirror can not meet the design requirement for the first critical speed is less than the service speed. In all the physical dimensions of the rotating mirror, the circum radius of mirror body and natural frequency are negatively correlated and the degree of correlation is maximal. The first-order natural frequency in- creases from 459.4 Hz to 713.6 Hz, the rate of change is 55.3%, the first critical speed is up to 42 816 r/min, avoiding resonance successfully, and the fatigue strength of the new rotating mirror can meet the design requirement. (authors)

  20. Generator dynamics in aeroelastic analysis and simulations

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Hansen, Morten Hartvig; Iov, F.

    2003-01-01

    This report contains a description of a dynamic model for a doubly-fed induction generator. The model has physical input parameters (voltage, resistance, reactance etc.) and can be used to calculate rotor and stator currents, hence active and reactivepower. A perturbation method has been used...... to reduce the original generator model equations to a set of equations which can be solved with the same time steps as a typical aeroelastic code. The method is used to separate the fast transients of the modelfrom the slow variations and deduce a reduced order expression for the slow part. Dynamic effects...... of the first order terms in the model as well as the influence on drive train eigenfrequencies and damping has been investigated. Load response during timesimulation of wind turbine response have been compared to simulations with a traditional static generator model based entirely on the slip angle. A 2 MW...

  1. Dynamic characteristics of soil respiration in Yellow River Delta wetlands, China

    Science.gov (United States)

    Wang, Xiao; Luo, Xianxiang; Jia, Hongli; Zheng, Hao

    2018-02-01

    The stable soil carbon (C) pool in coastal wetlands, referred to as "blue C", which has been extensively damaged by climate change and soil degradation, is of importance to maintain global C cycle. Therefore, to investigate the dynamic characteristics of soil respiration rate and evaluate C budgets in coastal wetlands are urgently. In this study, the diurnal and seasonal variation of soil respiration rate in the reed wetland land (RL) and the bare wetland land (BL) was measured in situ with the dynamic gas-infrared CO2 method in four seasons, and the factors impacted on the dynamic characteristics of soil respiration were investigated. The results showed that the diurnal variation of soil respiration rate consistently presented a "U" curve pattern in April, July, and September, with the maximum values at 12:00 a.m. and the minimum values at 6:00 a.m. In the same season, the diurnal soil respiration rate in RL was significantly greater than those in BL (P respiration rate was 0.14, 0.42, and 0.39 μmol m-2 s-1 in RL, 0.05, 0.22, 0.13, and 0.01 μmol m-2 s-1 in BL, respectively. Soil surface temperature was the primary factor that influenced soil respiration, which was confirmed by the exponential positive correlation between the soil respiration rate and soil surface temperature in BL and RL (P respiration, confirming by the significantly negative correlation between soil respiration rate and the content of soluble salt. These results will be useful for understanding the mechanisms underlying soil respiration and elevating C sequestration potential in the coastal wetlands.

  2. Identification of nuclear reactor characteristics by the reactor noise analysis

    International Nuclear Information System (INIS)

    Yashima, Hideyuki

    1980-01-01

    Reactor noise analysis method was applied to TRIGA II Research Reactor (Atomic Research Laboratory, Musashi Institute of Technology) and computed power spectral density (PSD) from the CIC current record. PSD has provided many valuable informations regarding to the reactor kinetics, including the effect of control rods vibration. Another information of neutron physics parameters were obtained and this result was compared with the parameter which was formerly measured by the Feynman-α experiment. Through these experiments we could find overall frequency characteristics of TRIGA II Reactor. (author)

  3. Dynamic response analysis as a tool for investigating transport mechanisms

    International Nuclear Information System (INIS)

    Dudok de Wit, Th.; Joye, B.; Lister, J.B.; Moret, J.M.

    1990-01-01

    Dynamic response analysis provides an attractive method for studying transport mechanisms in tokamak plasmas. The analysis of the radial response has already been widely used for heat and particle transport studies. The frequency dependence of the dynamic response, which is often omitted, reveals further properties of the dominant transport mechanisms. Extended measurements of the soft X-ray emission were carried out on the TCA tokamak in order to determine the underlying transport processes. (author) 5 refs., 2 figs

  4. Dynamic analysis of a parasite population model

    Science.gov (United States)

    Sibona, G. J.; Condat, C. A.

    2002-03-01

    We study the dynamics of a model that describes the competitive interaction between an invading species (a parasite) and its antibodies in an living being. This model was recently used to examine the dynamical competition between Tripanosoma cruzi and its antibodies during the acute phase of Chagas' disease. Depending on the antibody properties, the model yields three types of outcomes, corresponding, respectively, to healing, chronic disease, and host death. Here, we study the dynamics of the parasite-antibody interaction with the help of simulations, obtaining phase trajectories and phase diagrams for the system. We show that, under certain conditions, the size of the parasite inoculation can be crucial for the infection outcome and that a retardation in the stimulated production of an antibody species may result in the parasite gaining a definitive advantage. We also find a criterion for the relative sizes of the parameters that are required if parasite-generated decoys are indeed to help the invasion. Decoys may also induce a qualitatively different outcome: a limit cycle for the antibody-parasite population phase trajectories.

  5. Analysis of Uncertainty in Dynamic Processes Development of Banks Functioning

    Directory of Open Access Journals (Sweden)

    Aleksei V. Korovyakovskii

    2013-01-01

    Full Text Available The paper offers the approach to measure of uncertainty estimation in dynamic processes of banks functioning, using statistic data of different banking operations indicators. To calculate measure of uncertainty in dynamic processes of banks functioning the phase images of relevant sets of statistic data are considered. Besides, it is shown that the form of phase image of the studied sets of statistic data can act as a basis of measure of uncertainty estimation in dynamic processes of banks functioning. The set of analytical characteristics are offered to formalize the form of phase image definition of the studied sets of statistic data. It is shown that the offered analytical characteristics consider inequality of changes in values of the studied sets of statistic data, which is one of the ways of uncertainty display in dynamic processes development. The invariant estimates of measure of uncertainty in dynamic processes of banks functioning, considering significant changes in absolute values of the same indicators for different banks were obtained. The examples of calculation of measure of uncertainty in dynamic processes of concrete banks functioning were cited.

  6. Combustion Property Analysis and Control System for the Dynamics of a Single Cylinder Diesel Engine

    Directory of Open Access Journals (Sweden)

    Bambang Wahono

    2013-12-01

    Full Text Available Corresponding to global environment problems in recent year, the technology for reducing fuel consumption and exhaust gas emission of engine was needed. Simulation of transient engine response is needed to predict engine performance that frequently experience rapid changes of speed. The aim of this research is to develop a non-linear dynamic control model for direct injection single cylinder diesel engine which can simulate engine performance under transient conditions. In this paper, the combustion model with multistage injection and conducted experiments in the transient conditions to clarify the combustion characteristics was proposed. In order to perform the analysis of acceleration operation characteristics, it was built a Model Predictive Control (MPC to reproduce the characteristic values of the exhaust gas and fuel consumption from the control parameters in particular. Finally, MPC is an effective method to perform the analysis of characteristic in diesel engine under transient conditions.

  7. Passivity analysis of higher order evolutionary dynamics and population games

    KAUST Repository

    Mabrok, Mohamed

    2017-01-05

    Evolutionary dynamics describe how the population composition changes in response to the fitness levels, resulting in a closed-loop feedback system. Recent work established a connection between passivity theory and certain classes of population games, namely so-called “stable games”. In particular, it was shown that a combination of stable games and (an analogue of) passive evolutionary dynamics results in stable convergence to Nash equilibrium. This paper considers the converse question of necessary conditions for evolutionary dynamics to exhibit stable behaviors for all generalized stable games. Using methods from robust control analysis, we show that if an evolutionary dynamic does not satisfy a passivity property, then it is possible to construct a generalized stable game that results in instability. The results are illustrated on selected evolutionary dynamics with particular attention to replicator dynamics, which are also shown to be lossless, a special class of passive systems.

  8. Analysis of the Single Toggle Jaw Crusher Force Transmission Characteristics

    Directory of Open Access Journals (Sweden)

    Moses Frank Oduori

    2016-01-01

    Full Text Available This paper sets out to perform a static force analysis of the single toggle jaw crusher mechanism and to obtain the force transmission characteristics of the mechanism. In order to obtain force transmission metrics that are characteristic of the structure of the mechanism, such influences as friction, dead weight, and inertia are considered to be extraneous and neglected. Equations are obtained by considering the balance of forces at the moving joints and appropriately relating these to the input torque and the output torque. A mechanical advantage, the corresponding transmitted torque, and the variations thereof, during the cycle of motion of the mechanism, are obtained. The mechanical advantage that characterizes the mechanism is calculated as the mean value over the active crushing stroke of the mechanism. The force transmission characteristics can be used as criteria for the comparison of different jaw crusher mechanism designs in order to select the most suitable design for a given application. The equations obtained can also be used in estimating the forces sustained by the components of the mechanism.

  9. The dynamic analysis facility at the Chalk River Nuclear Laboratories

    International Nuclear Information System (INIS)

    Argue, D.S.; Howatt, W.T.

    1979-10-01

    The Dynamic Analysis Facility at the Chalk River Nuclear Laboratories (CRNL) of Atomic Energy of Canada Limited (AECL) comprises a Hybrid Computer, consisting of two Applied Dynamic International AD/FIVE analog computers and a Digital Equipment Corporation (DEC) PDP-11/55 digital computer, and a Program Development System based on a DEC PDP-11/45 digital computer. This report describes the functions of the various hardware components of the Dynamic Analysis Facility and the interactions between them. A brief description of the software available to the user is also given. (auth)

  10. Study of the dynamic operational characteristics of the Taiwan Power Company system - a nuclear majority system

    International Nuclear Information System (INIS)

    Yu, I.H.

    1982-01-01

    All conclusions drawn in this dissertation are based on the results of about six hundred study cases. The dynamic characteristics of the present Taiwan Power Company system are very different not only from the characteristics of any other power system in the world but also from Taipower's own history characteristics. Based on the engineers' knowledge, this dissertation takes a calculation risk approach to deal with the problems in the energy systems. Chapter I introduces the information related with the stability of the present Taipower system. Taipower operating engineers are facing the problem of committing a large amount of nuclear generation at a low base load level. The general introduction of the stability program developed for this study is described in Chapter II. In Chapter III, the processes of performing the transient stability study are explained to show how this study was performed. Critical tie flows were suggested in Chapter IV, which might help balance the nuclear generation and thermal generation at the base load level and plan the unit maintenance schedule. Several operation modes which may increase the degree of stability or minimize the number unit trippings were discussed in Chapter V. In Chapter VI, how to adjust the load shedding policy to improve the stability are discussed. The remote tripping scheme which is effective in preventing massive system blackout was studied in Chapter VII. Some broader concepts in load management are presented in Chapter VII for Taipower's management decision

  11. A new neuro-fuzzy training algorithm for identifying dynamic characteristics of smart dampers

    International Nuclear Information System (INIS)

    Nguyen, Sy Dzung; Choi, Seung-Bok

    2012-01-01

    This paper proposes a new algorithm, named establishing neuro-fuzzy system (ENFS), to identify dynamic characteristics of smart dampers such as magnetorheological (MR) and electrorheological (ER) dampers. In the ENFS, data clustering is performed based on the proposed algorithm named partitioning data space (PDS). Firstly, the PDS builds data clusters in joint input–output data space with appropriate constraints. The role of these constraints is to create reasonable data distribution in clusters. The ENFS then uses these clusters to perform the following tasks. Firstly, the fuzzy sets expressing characteristics of data clusters are established. The structure of the fuzzy sets is adjusted to be suitable for features of the data set. Secondly, an appropriate structure of neuro-fuzzy (NF) expressed by an optimal number of labeled data clusters and the fuzzy-set groups is determined. After the ENFS is introduced, its effectiveness is evaluated by a prediction-error-comparative work between the proposed method and some other methods in identifying numerical data sets such as ‘daily data of stock A’, or in identifying a function. The ENFS is then applied to identify damping force characteristics of the smart dampers. In order to evaluate the effectiveness of the ENFS in identifying the damping forces of the smart dampers, the prediction errors are presented by comparing with experimental results. (paper)

  12. A new neuro-fuzzy training algorithm for identifying dynamic characteristics of smart dampers

    Science.gov (United States)

    Dzung Nguyen, Sy; Choi, Seung-Bok

    2012-08-01

    This paper proposes a new algorithm, named establishing neuro-fuzzy system (ENFS), to identify dynamic characteristics of smart dampers such as magnetorheological (MR) and electrorheological (ER) dampers. In the ENFS, data clustering is performed based on the proposed algorithm named partitioning data space (PDS). Firstly, the PDS builds data clusters in joint input-output data space with appropriate constraints. The role of these constraints is to create reasonable data distribution in clusters. The ENFS then uses these clusters to perform the following tasks. Firstly, the fuzzy sets expressing characteristics of data clusters are established. The structure of the fuzzy sets is adjusted to be suitable for features of the data set. Secondly, an appropriate structure of neuro-fuzzy (NF) expressed by an optimal number of labeled data clusters and the fuzzy-set groups is determined. After the ENFS is introduced, its effectiveness is evaluated by a prediction-error-comparative work between the proposed method and some other methods in identifying numerical data sets such as ‘daily data of stock A’, or in identifying a function. The ENFS is then applied to identify damping force characteristics of the smart dampers. In order to evaluate the effectiveness of the ENFS in identifying the damping forces of the smart dampers, the prediction errors are presented by comparing with experimental results.

  13. Monitoring urban greenness dynamics using multiple endmember spectral mixture analysis.

    Directory of Open Access Journals (Sweden)

    Muye Gan

    Full Text Available Urban greenness is increasingly recognized as an essential constituent of the urban environment and can provide a range of services and enhance residents' quality of life. Understanding the pattern of urban greenness and exploring its spatiotemporal dynamics would contribute valuable information for urban planning. In this paper, we investigated the pattern of urban greenness in Hangzhou, China, over the past two decades using time series Landsat-5 TM data obtained in 1990, 2002, and 2010. Multiple endmember spectral mixture analysis was used to derive vegetation cover fractions at the subpixel level. An RGB-vegetation fraction model, change intensity analysis and the concentric technique were integrated to reveal the detailed, spatial characteristics and the overall pattern of change in the vegetation cover fraction. Our results demonstrated the ability of multiple endmember spectral mixture analysis to accurately model the vegetation cover fraction in pixels despite the complex spectral confusion of different land cover types. The integration of multiple techniques revealed various changing patterns in urban greenness in this region. The overall vegetation cover has exhibited a drastic decrease over the past two decades, while no significant change occurred in the scenic spots that were studied. Meanwhile, a remarkable recovery of greenness was observed in the existing urban area. The increasing coverage of small green patches has played a vital role in the recovery of urban greenness. These changing patterns were more obvious during the period from 2002 to 2010 than from 1990 to 2002, and they revealed the combined effects of rapid urbanization and greening policies. This work demonstrates the usefulness of time series of vegetation cover fractions for conducting accurate and in-depth studies of the long-term trajectories of urban greenness to obtain meaningful information for sustainable urban development.

  14. Understanding dynamics using sensitivity analysis: caveat and solution

    Science.gov (United States)

    2011-01-01

    Background Parametric sensitivity analysis (PSA) has become one of the most commonly used tools in computational systems biology, in which the sensitivity coefficients are used to study the parametric dependence of biological models. As many of these models describe dynamical behaviour of biological systems, the PSA has subsequently been used to elucidate important cellular processes that regulate this dynamics. However, in this paper, we show that the PSA coefficients are not suitable in inferring the mechanisms by which dynamical behaviour arises and in fact it can even lead to incorrect conclusions. Results A careful interpretation of parametric perturbations used in the PSA is presented here to explain the issue of using this analysis in inferring dynamics. In short, the PSA coefficients quantify the integrated change in the system behaviour due to persistent parametric perturbations, and thus the dynamical information of when a parameter perturbation matters is lost. To get around this issue, we present a new sensitivity analysis based on impulse perturbations on system parameters, which is named impulse parametric sensitivity analysis (iPSA). The inability of PSA and the efficacy of iPSA in revealing mechanistic information of a dynamical system are illustrated using two examples involving switch activation. Conclusions The interpretation of the PSA coefficients of dynamical systems should take into account the persistent nature of parametric perturbations involved in the derivation of this analysis. The application of PSA to identify the controlling mechanism of dynamical behaviour can be misleading. By using impulse perturbations, introduced at different times, the iPSA provides the necessary information to understand how dynamics is achieved, i.e. which parameters are essential and when they become important. PMID:21406095

  15. Investigation of Apple Vibration Characteristics Using Finite Element Modal Analysis

    Directory of Open Access Journals (Sweden)

    R Mirzaei

    2013-02-01

    Full Text Available The most important quality indicator of fruits is the flesh firmness which is well correlated to their young’s modulus. In this research variation of vibration characteristics (shape modes, natural frequency of apple due to change of material characteristics (density, young's models, Poisson ratio and apple volume was investigated using Finite Element simulation. An image processing technique was used to obtain an unsymmetrical and non-spherical geometric model of apple. The exact three-dimensional shape of the fruit was created by determining the coordinates of apple surface and forming uneven rotational curvatures. Modal analysis with no boundary constraints has been applied. The first 20 Eigen frequencies and the corresponding mode shape were determined. Six rigid body modes possess zero resonant frequency which is related to the degree of freedom of a rigid body in space indicated the validity of finite element model. The modal analysis results showed that resonant frequency increased by increasing young's modulus of the fruit, while it decreased by increasing apple density. First mode torsion has a mean resonant frequency of 584 Hz. Variations of natural frequency due to change in young's modulus, density, and Poisson ratio were 80%, 11% and 4%, respectively. Coefficient of variation of resonant frequency in response to changing young's modulus was 2-3 times of that of density which shows the greatest effect of young modulus changes on natural frequency of fruits. Consequently with determination of fruits' natural frequency, their young modulus and firmness can be estimated.

  16. Dynamic Analysis of The Intelligent Sprayer Boom

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Maagaard, Jørgen; Terp, Christian Istjord

    called “The intelligent sprayer boom”. For the sprayer boom the primary challenge is to hit the weeds with precision from a movable platform. Since the sprayer boom is mounted on a tractor the system will react to bumps in the field. The intelligent sprayer boom has an integrated camera technology......As part of the 3 year project “The intelligent Sprayer Boom”, financed by The Danish National Advanced Technology Foundation, the dynamics of the sprayer boom is to be analysed. In order to minimize the amount of herbicides used to kill the weeds in agriculture a new sprayer boom is being developed...

  17. Finite-element analysis of dynamic fracture

    Science.gov (United States)

    Aberson, J. A.; Anderson, J. M.; King, W. W.

    1976-01-01

    Applications of the finite element method to the two dimensional elastodynamics of cracked structures are presented. Stress intensity factors are computed for two problems involving stationary cracks. The first serves as a vehicle for discussing lumped-mass and consistent-mass characterizations of inertia. In the second problem, the behavior of a photoelastic dynamic tear test specimen is determined for the time prior to crack propagation. Some results of a finite element simulation of rapid crack propagation in an infinite body are discussed.

  18. Dynamic Path Analysis in Life-Course Epidemiology

    DEFF Research Database (Denmark)

    Gamborg, Michael Orland; Boje Jensen, Gorm; Sørensen, Thorkild I.A.

    2011-01-01

    it works through other risk factors. In this paper, the dynamic path analysis model is presented as a tool to analyze these dynamic mechanisms in life-course epidemiology. A key feature of dynamic path analysis is its ability to decompose the total effect of a risk factor into a direct effect (not mediated...... by other variables) and indirect effects (mediated through other variables). This is illustrated by examining the associations between repeated measurements of body mass index (BMI) and systolic blood pressure (SBP) and the risk of CHD in a sample of Danish men between 1976 and 2006. The effect of baseline...... BMI on the risk of CHD is decomposed into a direct effect and indirect effects going through later BMI, concurrent SBP, or later SBP. In conclusion, dynamic path analysis is a flexible tool that by the decomposition of effects can be used to increase the understanding of mechanisms that underlie...

  19. Application of dynamic response analysis to JET heat pulse data

    International Nuclear Information System (INIS)

    Griguoli, A.; Sips, A.C.C.

    1993-09-01

    The plasma dynamic response can be used to study transport processes in a tokamak plasma. A method has been developed for the application of dynamic response analysis to study perturbations away from the plasma equilibrium. In this report perturbations on the electron temperature following a sawtooth collapse in the center of the plasma are considered. The method has been used to find mathematical description of a series of heat pulses at the Joint European Torus project (JET). From the plasma dynamic response, the time constants which characterise the heat pulse are obtained. These time constants are compared to the transport coefficients found in previous analysis of the JET heat pulse data. Various methods are discussed for applying dynamic response analysis to JET heat pulse data. (author)

  20. Dynamic Analysis of Wind Turbine Towers on Flexible Foundations

    Directory of Open Access Journals (Sweden)

    S. Adhikari

    2012-01-01

    Full Text Available Offshore wind turbines are considered as an essential part to develop sustainable, alternative energy sources. The structures themselves are both slender and highly flexible, with a subsea foundation typically consisting of a single large diameter monopile. They are subject to intense wind and wave loadings, with the result that significant movement of both the exposed structure and the upper part of the monopile can occur. Although the structures are intended for design life of 25 to 30 years, very little is known about the long term behaviour of these structures. This paper characterizes the dynamic behaviour of these structures. A simplified approach has been proposed for the free vibration analysis of wind turbines taking the effect of foundation into account. The method is based on an Euler-Bernoulli beam-column with elastic end supports. The elastic end-supports are considered to model the flexible nature of the interaction of these systems with the foundation. A closed-form expression of the characteristic equation governing all the natural frequencies of the system has been derived. Theoretical developments are explained by practical numerical examples. Analytical as well as a new experimental approach has been proposed to determine the parameters for the foundation. Some design issues of wind turbine towers are discussed from the point of view of the foundation parameters.

  1. Dynamic analysis of auxiliary buildings in nuclear power plants

    International Nuclear Information System (INIS)

    Subramanian, K.V.; Madhava Rao, A.S.; Warudkar, A.S.

    1989-01-01

    All nuclear power plants have a large number of auxiliary buildings housing various services and control systems required for the operation of the plant. Illustrative examples are turbine building, control building, service building etc. These buildings are seismically qualified as Class I or Class II structures. Usually, these auxiliary buildings are of low rise type with two or three floors and floor heights varying from five to eight meters and of framed construction in steel or concrete or a combination of both the materials. The floors are usually staggered with large cutouts and may not extend over the full area in plan. Some of the bays are often of double story height with the columns continuous over a story in order to accommodate cranes and other equipment. The structural elements supporting the roof may consist of steel roof trusses instead of beams. The seismic analysis of these structures involves the formulation of the analytical model that can simulate the physical behavior of the structure as close as possible taking into consideration the practical aspects. The criteria adopted to formulate the mathematical model has an important bearing on the evaluated dynamic characteristics and seismic response

  2. Dynamics analysis of a boiling water reactor based on multivariable autoregressive modeling

    International Nuclear Information System (INIS)

    Oguma, Ritsuo; Matsubara, Kunihiko

    1980-01-01

    The establishment of the highly reliable mathematical model for the dynamic characteristics of a reactor is indispensable for the achievement of safe operation in reactor plants. The authors have tried to model the dynamic characteristics of a reactor based on the identification technique, taking the JPDR (Japan Power Demonstration Reactor) as the object, as one of the technical studies for diagnosing BWR anomaly, and employed the multivariable autoregressive modeling (MAR method) as one of the useful methods for forwarding the analysis. In this paper, the outline of the system analysis by MAR modeling is explained, and the identification experiments and their analysis results performed in the phase 4 of the power increase test of the JPDR are described. The authors evaluated the results of identification based on only reactor noises, making reference to the results of identification in the case of exciting the system by applying artificial irregular disturbance, in order to clarify the extent in which the modeling is possible by reactor noises only. However, some difficulties were encountered. The largest problem is the one concerning the separation and identification of the noise sources exciting the variables from the dynamic characteristics among the variables. If the effective technique can be obtained to this problem, the approach by the identification technique based on the probability model might be a powerful tool in the field of reactor noise analysis and the development of diagnosis technics. (Wakatsuki, Y.)

  3. Effects of stressor characteristics on early warning signs of critical transitions and "critical coupling" in complex dynamical systems.

    Science.gov (United States)

    Blume, Steffen O P; Sansavini, Giovanni

    2017-12-01

    Complex dynamical systems face abrupt transitions into unstable and catastrophic regimes. These critical transitions are triggered by gradual modifications in stressors, which push the dynamical system towards unstable regimes. Bifurcation analysis can characterize such critical thresholds, beyond which systems become unstable. Moreover, the stochasticity of the external stressors causes small-scale fluctuations in the system response. In some systems, the decomposition of these signal fluctuations into precursor signals can reveal early warning signs prior to the critical transition. Here, we present a dynamical analysis of a power system subjected to an increasing load level and small-scale stochastic load perturbations. We show that the auto- and cross-correlations of bus voltage magnitudes increase, leading up to a Hopf bifurcation point, and further grow until the system collapses. This evidences a gradual transition into a state of "critical coupling," which is complementary to the established concept of "critical slowing down." Furthermore, we analyze the effects of the type of load perturbation and load characteristics on early warning signs and find that gradient changes in the autocorrelation provide early warning signs of the imminent critical transition under white-noise but not for auto-correlated load perturbations. Furthermore, the cross-correlation between all voltage magnitude pairs generally increases prior to and beyond the Hopf bifurcation point, indicating "critical coupling," but cannot provide early warning indications. Finally, we show that the established early warning indicators are oblivious to limit-induced bifurcations and, in the case of the power system model considered here, only react to an approaching Hopf bifurcation.

  4. Dynamic Resonance Sensitivity Analysis in Wind Farms

    DEFF Research Database (Denmark)

    Ebrahimzadeh, Esmaeil; Blaabjerg, Frede; Wang, Xiongfei

    2017-01-01

    (PFs) are calculated by critical eigenvalue sensitivity analysis versus the entries of the MIMO matrix. The PF analysis locates the most exciting bus of the resonances, where can be the best location to install the passive or active filters to reduce the harmonic resonance problems. Time...

  5. Dynamic analysis of nuclear safeguards systems

    International Nuclear Information System (INIS)

    Wilson, J.R.; Rasmuson, D.M.; Tingey, F.H.

    1978-01-01

    The assessment of the safeguards/adversary system poses a unique challenge as evolving technology affects the capabilities of both. The method discussed meets this challenge using a flexible analysis which can be updated by system personnel. The automatically constructed event tree provides a rapid overview analysis for initial assessment, evaluation of changes, cost/benefit study and inspection and audit

  6. Collective Activity of Many Bistable Assemblies Reproduces Characteristic Dynamics of Multistable Perception.

    Science.gov (United States)

    Cao, Robin; Pastukhov, Alexander; Mattia, Maurizio; Braun, Jochen

    2016-06-29

    The timing of perceptual decisions depends on both deterministic and stochastic factors, as the gradual accumulation of sensory evidence (deterministic) is contaminated by sensory and/or internal noise (stochastic). When human observers view multistable visual displays, successive episodes of stochastic accumulation culminate in repeated reversals of visual appearance. Treating reversal timing as a "first-passage time" problem, we ask how the observed timing densities constrain the underlying stochastic accumulation. Importantly, mean reversal times (i.e., deterministic factors) differ enormously between displays/observers/stimulation levels, whereas the variance and skewness of reversal times (i.e., stochastic factors) keep characteristic proportions of the mean. What sort of stochastic process could reproduce this highly consistent "scaling property?" Here we show that the collective activity of a finite population of bistable units (i.e., a generalized Ehrenfest process) quantitatively reproduces all aspects of the scaling property of multistable phenomena, in contrast to other processes under consideration (Poisson, Wiener, or Ornstein-Uhlenbeck process). The postulated units express the spontaneous dynamics of attractor assemblies transitioning between distinct activity states. Plausible candidates are cortical columns, or clusters of columns, as they are preferentially connected and spontaneously explore a restricted repertoire of activity states. Our findings suggests that perceptual representations are granular, probabilistic, and operate far from equilibrium, thereby offering a suitable substrate for statistical inference. Spontaneous reversals of high-level perception, so-called multistable perception, conform to highly consistent and characteristic statistics, constraining plausible neural representations. We show that the observed perceptual dynamics would be reproduced quantitatively by a finite population of distinct neural assemblies, each with

  7. Empirically characteristic analysis of chaotic PID controlling particle swarm optimization.

    Science.gov (United States)

    Yan, Danping; Lu, Yongzhong; Zhou, Min; Chen, Shiping; Levy, David

    2017-01-01

    Since chaos systems generally have the intrinsic properties of sensitivity to initial conditions, topological mixing and density of periodic orbits, they may tactfully use the chaotic ergodic orbits to achieve the global optimum or their better approximation to given cost functions with high probability. During the past decade, they have increasingly received much attention from academic community and industry society throughout the world. To improve the performance of particle swarm optimization (PSO), we herein propose a chaotic proportional integral derivative (PID) controlling PSO algorithm by the hybridization of chaotic logistic dynamics and hierarchical inertia weight. The hierarchical inertia weight coefficients are determined in accordance with the present fitness values of the local best positions so as to adaptively expand the particles' search space. Moreover, the chaotic logistic map is not only used in the substitution of the two random parameters affecting the convergence behavior, but also used in the chaotic local search for the global best position so as to easily avoid the particles' premature behaviors via the whole search space. Thereafter, the convergent analysis of chaotic PID controlling PSO is under deep investigation. Empirical simulation results demonstrate that compared with other several chaotic PSO algorithms like chaotic PSO with the logistic map, chaotic PSO with the tent map and chaotic catfish PSO with the logistic map, chaotic PID controlling PSO exhibits much better search efficiency and quality when solving the optimization problems. Additionally, the parameter estimation of a nonlinear dynamic system also further clarifies its superiority to chaotic catfish PSO, genetic algorithm (GA) and PSO.

  8. Dynamic Characteristics of Communication Lines with Distributed Parameters to Control the Throttle-controlled Hydraulic Actuators

    Directory of Open Access Journals (Sweden)

    D. N. Popov

    2015-01-01

    Full Text Available The article considers a mathematical model of the hydraulic line for remote control of electro-hydraulic servo drive (EHSD with throttle control. This type of hydraulic lines is designed as a backup to replace the electrical connections, which are used to control EHSD being remote from the site with devices located to form the control signals of any object. A disadvantage of electric connections is that they are sensitive to magnetic fields and thereby do not provide the required reliability of the remote control. Hydraulic lines have no this disadvantage and therefore are used in aircraft and other industrial systems. However, dynamic characteristics of hydraulic systems still have been investigated insufficiently in the case of transmitting control signals at a distance at which the signal may be distorted when emerging the wave processes.The article results of mathematical simulation, which are verified through physical experimentation, largely eliminate the shortcomings of said information.The mathematical model described in the paper is based on the theory of unsteady pressure compressible fluids. In the model there are formulas that provide calculation of frequency characteristics of the hydraulic lines under hydraulic oscillations of the laminar flow parameters of viscous fluid.A real mock-up of the system under consideration and an experimental ad hoc unit are used to verify the results of mathematically simulated hydraulic systems.Calculated logarithmic amplitude and phase frequency characteristics compared with those obtained experimentally prove, under certain conditions, the proposed theoretical method of calculation. These conditions have to ensure compliance with initial parameters of fluid defined under stationary conditions. The applied theory takes into consideration a non-stationary hydraulic resistance of the line when calculating frequency characteristics.The scientific novelty in the article material is presented in

  9. Dynamic analysis of a pumped-storage hydropower plant with random power load

    Science.gov (United States)

    Zhang, Hao; Chen, Diyi; Xu, Beibei; Patelli, Edoardo; Tolo, Silvia

    2018-02-01

    This paper analyzes the dynamic response of a pumped-storage hydropower plant in generating mode. Considering the elastic water column effects in the penstock, a linearized reduced order dynamic model of the pumped-storage hydropower plant is used in this paper. As the power load is always random, a set of random generator electric power output is introduced to research the dynamic behaviors of the pumped-storage hydropower plant. Then, the influences of the PI gains on the dynamic characteristics of the pumped-storage hydropower plant with the random power load are analyzed. In addition, the effects of initial power load and PI parameters on the stability of the pumped-storage hydropower plant are studied in depth. All of the above results will provide theoretical guidance for the study and analysis of the pumped-storage hydropower plant.

  10. Dynamic Characteristics of The DSI-Type Constant-Flow Valves

    Science.gov (United States)

    Kang, Yuan; Hu, Sheng-Yan; Chou, Hsien-Chin; Lee, Hsing-Han

    Constant flow valves have been presented in industrial applications or academic studies, which compensate recess pressures of a hydrostatic bearing to resist load fluctuating. The flow rate of constant-flow valves can be constant in spite of the pressure changes in recesses, however the design parameters must be specified. This paper analyzes the dynamic responses of DSI-type constant-flow valves that is designed as double pistons on both ends of a spool with single feedback of working pressure and regulating restriction at inlet. In this study the static analysis presents the specific relationships among design parameters for constant flow rate and the dynamic analyses give the variations around the constant flow rate as the working pressure fluctuates.

  11. Dynamic Analysis of Cable-Stayed Bridges Affected by Accidental Failure Mechanisms under Moving Loads

    Directory of Open Access Journals (Sweden)

    Fabrizio Greco

    2013-01-01

    Full Text Available The dynamic behavior of cable-stayed bridges subjected to moving loads and affected by an accidental failure in the cable suspension system is investigated. The main aim of the paper is to quantify, numerically, the dynamic amplification factors of typical kinematic and stress design variables, by means of a parametric study developed in terms of the structural characteristics of the bridge components. The bridge formulation is developed by using a geometric nonlinear formulation, in which the effects of local vibrations of the stays and of large displacements in the girder and the pylons are taken into account. Explicit time dependent damage laws, reproducing the failure mechanism in the cable system, are considered to investigate the influence of the failure mode characteristics on the dynamic bridge behavior. The analysis focuses attention on the influence of the inertial characteristics of the moving loads, by accounting coupling effects arising from the interaction between girder and moving system. Sensitivity analyses of typical design bridge variables are proposed. In particular, the effects produced by the moving system characteristics, the tower typologies, and the failure mode characteristics involved in the cable system are investigated by means of comparisons between damaged and undamaged bridge configurations.

  12. The power law and dynamic rheology in food analysis

    Science.gov (United States)

    Protein networks impart functional and structural characteristics to food, and should be examined to gain an understanding of properties of the product. Food matrices are investigated nondestructively by small amplitude oscillatory shear analysis, which provides information on viscoelasticity, incl...

  13. Dynamic analysis of the condensate feedwater system in boiling water reactor plants

    International Nuclear Information System (INIS)

    Tanji, J.; Omori, T.

    1982-01-01

    The computer code, CONFAC, has been developed for dynamic analysis of the condensate feedwater system in boiling water reactor plants. This code simulates the hydrodynamics in the piping system, the pump dynamics, and the feedwater controller in order to clarify the system transient characteristics in such cases as pump trip incidents. Code verification was performed by comparison between analytical results and actual plant operational data. Satisfactory agreement was obtained. With the code, appropriate pump start/stop interlocks were estimated for preventing pump cavitation in pump trip incidents

  14. Normal dynamic deformation characteristics of non-consecutive jointed rock masses under impact loads

    Science.gov (United States)

    Zeng, Sheng; Jiang, Bowei; Sun, Bing

    2017-08-01

    In order to study deformation characteristics of non-consecutive single jointed rock masses under impact loads, we used the cement mortar materials to make simulative jointed rock mass samples, and tested the samples under impact loads by the drop hammer. Through analyzing the time-history signal of the force and the displacement, first we find that the dynamic compression displacement of the jointed rock mass is significantly larger than that of the intact jointless rock mass, the compression displacement is positively correlated with the joint length and the impact height. Secondly, the vertical compressive displacement of the jointed rock mass is mainly due to the closure of opening joints under small impact loads. Finally, the peak intensity of the intact rock mass is larger than that of the non-consecutive jointed rock mass and negatively correlated with the joint length under the same impact energy.

  15. Evaluation of dynamic characteristics of hard rock based on numerical simulations of in situ rock tests

    International Nuclear Information System (INIS)

    Yamagami, Yuya; Ikusada, Koji; Jiang, Yujing

    2009-01-01

    In situ rock tests of hard rock of conglomerate in which discontinuities in high angle are dominant were conducted. In this study, in order to confirm the validity of the test results and the test condition, and in order to elucidate the deformation behaviour and the mechanism of shear strength of the rock mass, the numerical simulations of the in situ rock tests by using distinct element method were performed. As a result, it was clarified that the behaviour of the rock mass strongly depends on both geometrical distribution of discontinuities and those mechanical properties. It is thought that a series of evaluation processes showed in this study contribute to improve the reliability of the dynamic characteristic evaluation of the rock mass. (author)

  16. Wheat yield dynamics: a structural econometric analysis.

    Science.gov (United States)

    Sahin, Afsin; Akdi, Yilmaz; Arslan, Fahrettin

    2007-10-15

    In this study we initially have tried to explore the wheat situation in Turkey, which has a small-open economy and in the member countries of European Union (EU). We have observed that increasing the wheat yield is fundamental to obtain comparative advantage among countries by depressing domestic prices. Also the changing structure of supporting schemes in Turkey makes it necessary to increase its wheat yield level. For this purpose, we have used available data to determine the dynamics of wheat yield by Ordinary Least Square Regression methods. In order to find out whether there is a linear relationship among these series we have checked each series whether they are integrated at the same order or not. Consequently, we have pointed out that fertilizer usage and precipitation level are substantial inputs for producing high wheat yield. Furthermore, in respect for our model, fertilizer usage affects wheat yield more than precipitation level.

  17. Nonlinear dynamic analysis of flexible multibody systems

    Science.gov (United States)

    Bauchau, Olivier A.; Kang, Nam Kook

    1991-01-01

    Two approaches are developed to analyze the dynamic behavior of flexible multibody systems. In the first approach each body is modeled with a modal methodology in a local non-inertial frame of reference, whereas in the second approach, each body is modeled with a finite element methodology in the inertial frame. In both cases, the interaction among the various elastic bodies is represented by constraint equations. The two approaches were compared for accuracy and efficiency: the first approach is preferable when the nonlinearities are not too strong but it becomes cumbersome and expensive to use when many modes must be used. The second approach is more general and easier to implement but could result in high computation costs for a large system. The constraints should be enforced in a time derivative fashion for better accuracy and stability.

  18. Analysis of A Virus Dynamics Model

    Science.gov (United States)

    Zhang, Baolin; Li, Jianquan; Li, Jia; Zhao, Xin

    2018-03-01

    In order to more accurately characterize the virus infection in the host, a virus dynamics model with latency and virulence is established and analyzed in this paper. The positivity and boundedness of the solution are proved. After obtaining the basic reproduction number and the existence of infected equilibrium, the Lyapunov method and the LaSalle invariance principle are used to determine the stability of the uninfected equilibrium and infected equilibrium by constructing appropriate Lyapunov functions. We prove that, when the basic reproduction number does not exceed 1, the uninfected equilibrium is globally stable, the virus can be cleared eventually; when the basic reproduction number is more than 1, the infected equilibrium is globally stable, the virus will persist in the host at a certain level. The effect of virulence and latency on infection is also discussed.

  19. Decision Analysis of Dynamic Spectrum Access Rules

    Energy Technology Data Exchange (ETDEWEB)

    Juan D. Deaton; Luiz A. DaSilva; Christian Wernz

    2011-12-01

    A current trend in spectrum regulation is to incorporate spectrum sharing through the design of spectrum access rules that support Dynamic Spectrum Access (DSA). This paper develops a decision-theoretic framework for regulators to assess the impacts of different decision rules on both primary and secondary operators. We analyze access rules based on sensing and exclusion areas, which in practice can be enforced through geolocation databases. Our results show that receiver-only sensing provides insufficient protection for primary and co-existing secondary users and overall low social welfare. On the other hand, using sensing information between the transmitter and receiver of a communication link, provides dramatic increases in system performance. The performance of using these link end points is relatively close to that of using many cooperative sensing nodes associated to the same access point and large link exclusion areas. These results are useful to regulators and network developers in understanding in developing rules for future DSA regulation.

  20. Dynamic Analysis of Emotions through Artificial Intelligence

    Directory of Open Access Journals (Sweden)

    Susana Mejía M.

    2016-04-01

    Full Text Available Emotions have been demonstrated to be an important aspect of human intelligence and to play a significant role in human decision-making processes. Emotions are not only feelings but also processes of establishing, maintaining or disrupting the relation between the organism and the environment. In the present paper, several features of social and developmental Psychology are introduced, especially concepts that are related to Theories of Emotions and the Mathematical Tools applied in psychology (i.e., Dynamic Systems and Fuzzy Logic. Later, five models that infer emotions from a single event, in AV-Space, are presented and discussed along with the finding that fuzzy logic can measure human emotional states

  1. Analysis and control of complex dynamical systems robust bifurcation, dynamic attractors, and network complexity

    CERN Document Server

    Imura, Jun-ichi; Ueta, Tetsushi

    2015-01-01

    This book is the first to report on theoretical breakthroughs on control of complex dynamical systems developed by collaborative researchers in the two fields of dynamical systems theory and control theory. As well, its basic point of view is of three kinds of complexity: bifurcation phenomena subject to model uncertainty, complex behavior including periodic/quasi-periodic orbits as well as chaotic orbits, and network complexity emerging from dynamical interactions between subsystems. Analysis and Control of Complex Dynamical Systems offers a valuable resource for mathematicians, physicists, and biophysicists, as well as for researchers in nonlinear science and control engineering, allowing them to develop a better fundamental understanding of the analysis and control synthesis of such complex systems.

  2. Integrating atomistic molecular dynamics simulations, experiments, and network analysis to study protein dynamics

    DEFF Research Database (Denmark)

    Papaleo, Elena

    2015-01-01

    that we observe and the functional properties of these important cellular machines. To make progresses in this direction, we need to improve the physical models used to describe proteins and solvent in molecular dynamics, as well as to strengthen the integration of experiments and simulations to overcome...... with the possibility to validate simulation methods and physical models against a broad range of experimental observables. On the other side, it also allows a complementary and comprehensive view on protein structure and dynamics. What is needed now is a better understanding of the link between the dynamic properties...... simulations with attention to the effects that can be propagated over long distances and are often associated to important biological functions. In this context, approaches inspired by network analysis can make an important contribution to the analysis of molecular dynamics simulations....

  3. The application of DCPD method to evaluating dynamic J-R fracture resistance characteristics

    International Nuclear Information System (INIS)

    Yoon, Ji Hyun; Hong, Jun Hwa; Lee, Bong Sang; Chi, Se Whan; Kim, Joo Hag; Oh, Yong Jun; Kwun, Sun Chil; Oh, Jong Myung

    1999-06-01

    The reliable DCPD (Direct Current Potential Drop) test and data acquisition system were developed on the basis of analysis of various technical problems to accompanied with the application of DCPD method to J-R fracture resistance test. The test system contains electric insulation rod and high performance data acquisition system. The test and analysis method was applied to J-R fracture resistance test for SA516-Gr.70 steel for nuclear primary coolant system elbow. The reliabilities of test and analysis method were confirmed through the load-ratio method in case of dynamic loading test, and through the standard unloading compliance test in case of static loading test. (author). 17 refs., 1 tab., 18 figs

  4. The application of DCPD method to evaluating dynamic J-R fracture resistance characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ji Hyun; Hong, Jun Hwa; Lee, Bong Sang; Chi, Se Whan; Kim, Joo Hag; Oh, Yong Jun; Kwun, Sun Chil; Oh, Jong Myung

    1999-06-01

    The reliable DCPD (Direct Current Potential Drop) test and data acquisition system were developed on the basis of analysis of various technical problems to accompanied with the application of DCPD method to J-R fracture resistance test. The test system contains electric insulation rod and high performance data acquisition system. The test and analysis method was applied to J-R fracture resistance test for SA516-Gr.70 steel for nuclear primary coolant system elbow. The reliabilities of test and analysis method were confirmed through the load-ratio method in case of dynamic loading test,and through the standard unloading compliance test in case of static loading test. (author). 17 refs., 1 tab., 18 figs.

  5. Conducting Qualitative Data Analysis: Managing Dynamic Tensions within

    Science.gov (United States)

    Chenail, Ronald J.

    2012-01-01

    In the third of a series of "how-to" essays on conducting qualitative data analysis, Ron Chenail examines the dynamic tensions within the process of qualitative data analysis that qualitative researchers must manage in order to produce credible and creative results. These tensions include (a) the qualities of the data and the qualitative data…

  6. Full Dynamic Analysis of Mooring Solution Candidates - First Iteration

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Ferri, Francesco

    This report covers an initial full dynamic analysis of the mooring solutions for the four wave energy converters in the project “Mooring Solutions for Large Wave Energy Converters”. The analysis tends to provide the first understanding of the layouts and provide discussion on what parameters that...

  7. Steady and dynamic states analysis of induction motor: FEA approach

    African Journals Online (AJOL)

    This paper deals with the steady and dynamic states analysis of induction motor using finite element analysis (FEA) approach. The motor has aluminum rotor bars and is designed for direct-on-line operation at 50 Hz. A study of the losses occurring in the motor performed at operating frequency of 50Hz showed that stator ...

  8. Dynamic thermal analysis of machines in running state

    CERN Document Server

    Wang, Lihui

    2014-01-01

    With the increasing complexity and dynamism in today’s machine design and development, more precise, robust and practical approaches and systems are needed to support machine design. Existing design methods treat the targeted machine as stationery. Analysis and simulation are mostly performed at the component level. Although there are some computer-aided engineering tools capable of motion analysis and vibration simulation etc., the machine itself is in the dry-run state. For effective machine design, understanding its thermal behaviours is crucial in achieving the desired performance in real situation. Dynamic Thermal Analysis of Machines in Running State presents a set of innovative solutions to dynamic thermal analysis of machines when they are put under actual working conditions. The objective is to better understand the thermal behaviours of a machine in real situation while at the design stage. The book has two major sections, with the first section presenting a broad-based review of the key areas of ...

  9. Numerical research of dynamic characteristics in tower solar cavity receiver based on step-change radiation flux

    Science.gov (United States)

    Chen, Zhengwei; Wang, Yueshe; Hao, Yun; Wang, Qizhi

    2013-07-01

    The solar cavity receiver is an important light-energy to thermal-energy convector in the tower solar thermal power plant system. The heat flux in the inner surface of the cavity will show the characteristics of non-continuous step change especially in non-normal and transient weather conditions, which may result in a continuous dynamic variation of the characteristic parameters. Therefore, the research of dynamic characteristics of the receiver plays a very important role in the operation and the control safely in solar cavity receiver system. In this paper, based on the non-continuous step change of radiation flux, a non-linear dynamic model is put forward to obtain the effects of the non-continuous step change radiation flux and step change feed water flow on the receiver performance by sequential modular approach. The subject investigated in our study is a 1MW solar power station constructed in Yanqing County, Beijing. This study has obtained the dynamic responses of the characteristic parameters in the cavity receiver, such as drum pressure, drum water level, main steam flow and main steam enthalpy under step change radiation flux. And the influence law of step-change feed water flow to the dynamic characteristics in the receiver also has been analyzed. The results have a reference value for the safe operation and the control in solar cavity receiver system.

  10. Chaotic dynamic characteristics of pressure fluctuation signals in hydro-turbine

    Energy Technology Data Exchange (ETDEWEB)

    Su, Wen Tao; An, Shi [School of Management, Harbin Institute of Technology, Harbin (China); Li, Xiao Bin; Lan, Chao Feng; Li, Feng Chen [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin (China); Wang, Jian Sheng [Ministry of Education of China, Tianjin (China)

    2016-11-15

    The pressure fluctuation characteristics in a Francis hydro-turbine running at partial flow conditions were studied based on the chaotic dynamic methods. Firstly, the experimental data of pressure fluctuations in the draft tube at various flow conditions was de-noised using lifting wavelet transformation, then, for the de-noised signals, their spectrum distribution on the frequency domain, the energy variation and the energy partition accounting for the total energy was calculated. Hereby, for the flow conditions ranging from no cavitation to severe cavitation, the chaos dynamic features of fluctuation signals were analyzed, including the temporal-frequency distribution, phase trajectory, Lyapunov exponent and Poincaré map etc. It is revealed that, the main energy of pressure fluctuations in the draft tube locates at low-frequency region. As the cavitation grows, the amplitude of power spectrum at frequency domain becomes larger. For all the flow conditions, all the maximal Lyapunov exponents are larger than zero, and they increase with the cavitation level. Therefore, it is believed that there indeed exist the chaotic attractors in the pressure fluctuation signals for a hydro-turbine.

  11. CSF Venous Fistulas in Spontaneous Intracranial Hypotension: Imaging Characteristics on Dynamic and CT Myelography.

    Science.gov (United States)

    Kranz, Peter G; Amrhein, Timothy J; Gray, Linda

    2017-12-01

    The objective of this study is to describe the anatomic and imaging features of CSF venous fistulas, which are a recently reported cause of spontaneous intracranial hypotension (SIH). We retrospectively reviewed the records of patients with SIH caused by CSF venous fistulas who received treatment at our institution. The anatomic details of each fistula were recorded. Attenuation of the veins involved by the fistula was compared with that of adjacent control veins on CT myelography (CTM). Visibility of the CSF venous fistula on CTM and a modified conventional myelography technique we refer to as dynamic myelography was also compared. Twenty-two cases of CSF venous fistula were identified. The fistulas were located between T4 and L1. Ninety percent occurred without a concurrent epidural CSF leak. In most cases (82%), the CSF venous fistula originated from a nerve root sleeve diverticulum. On CTM, the abnormal veins associated with the CSF venous fistula were seen in a paravertebral location in 45% of cases, centrally within the epidural venous plexus in 32%, and lateral to the spine in 23%. Differences in attenuation between the fistula veins and the control veins was highly statistically significant (p CSF venous fistulas are an important cause of SIH that can be detected on both CTM and dynamic myelograph y and may occur without an epidural CSF leak. Familiarity with the imaging characteristics of these lesions is critical to providing appropriate treatment to patients with SIH.

  12. Effect of heat transfer tube leak on dynamic characteristic of steam generator

    International Nuclear Information System (INIS)

    Sun Baozhi; Shi Jianxin; Li Na; Zheng Lusong; Liu Shanghua; Lei Yu

    2015-01-01

    Taking the steam generator of Daya Bay Nuclear Power Station as the research object, one-dimensional dynamic model of the steam generator based on drift flux theory and leak model of heat transfer tube were established. Steady simulation of steam generator under different conditions was carried out. Based on verifying the drift flux model and leak model of heat transfer tube, the effect of leak location and flow rate under different conditions on steam generator's key parameters was studied. The results show that the drift flux model and leak model can reflect the law of key parameter change accurately such as vapor mass fraction and steam pressure under different leak cases. The variation of the parameters is most apparent when the leak is at the entrance of boiling section and vapor mass fraction varies from 0.261 to 0.163 when leakage accounts for 5% of coolant flow rate. The successful prediction of the effect of heat transfer tube leak on dynamic characteristics of the steam generator based on drift flux theory supplies some references for monitoring and taking precautionary measures to prevent heat transfer tube leak accident. (authors)

  13. Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air

    International Nuclear Information System (INIS)

    Wei Linsheng; Peng Bangfa; Li Ming; Zhang Yafang; Hu Zhaoji

    2016-01-01

    A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 10 4 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O 2 + , O 3 − and O 2 ( 1 Δg) in pulsed DBD in air, respectively. N 2 O has the largest density among nitrogen oxides. e and N 2 + densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O 2 + , O, O 3 , N 2 (A 3 Σ) and N 2 O densities reach maximum values in the vicinity of the anode. (paper)

  14. A rheonomic model for the dynamical analysis of the structure-soil interaction

    International Nuclear Information System (INIS)

    Chiroiu, V.; Nicolae, V.

    1993-01-01

    The dynamical analysis of the structure-soil interaction requires an adequate modeling of the geometrical radiation phenomenon (g.r.) i.e. the propagation of the vibrating energy of the structure in the infinite medium. Newton's law of motion is not including the g.r., considered in this paper like an irreversible phenomenon. To incorporate this, a new wave motion equation is proposed, according to a complete analysis of the structure-soil interactions with an adequate formulation of the g.r. By using a system of fundamental dynamical solutions, the rheonom constraint applied to the half-space is represented as a restriction to the displacement solutions. A dimensionless formulation of the problem and the variation of dynamical and energetical quantities in respect to the frequency, as according to the diagram of the characteristic curve of g.r. are presented numerically. Sample results showing the importance of radiation energy for several motions are also shown

  15. Modeling of human operator dynamics in simple manual control utilizing time series analysis. [tracking (position)

    Science.gov (United States)

    Agarwal, G. C.; Osafo-Charles, F.; Oneill, W. D.; Gottlieb, G. L.

    1982-01-01

    Time series analysis is applied to model human operator dynamics in pursuit and compensatory tracking modes. The normalized residual criterion is used as a one-step analytical tool to encompass the processes of identification, estimation, and diagnostic checking. A parameter constraining technique is introduced to develop more reliable models of human operator dynamics. The human operator is adequately modeled by a second order dynamic system both in pursuit and compensatory tracking modes. In comparing the data sampling rates, 100 msec between samples is adequate and is shown to provide better results than 200 msec sampling. The residual power spectrum and eigenvalue analysis show that the human operator is not a generator of periodic characteristics.

  16. Evaluating the impact of built environment characteristics on urban boundary layer dynamics using an advanced stochastic approach

    Directory of Open Access Journals (Sweden)

    J. Song

    2016-05-01

    Full Text Available Urban land–atmosphere interactions can be captured by numerical modeling framework with coupled land surface and atmospheric processes, while the model performance depends largely on accurate input parameters. In this study, we use an advanced stochastic approach to quantify parameter uncertainty and model sensitivity of a coupled numerical framework for urban land–atmosphere interactions. It is found that the development of urban boundary layer is highly sensitive to surface characteristics of built terrains. Changes of both urban land use and geometry impose significant impact on the overlying urban boundary layer dynamics through modification on bottom boundary conditions, i.e., by altering surface energy partitioning and surface aerodynamic resistance, respectively. Hydrothermal properties of conventional and green roofs have different impacts on atmospheric dynamics due to different surface energy partitioning mechanisms. Urban geometry (represented by the canyon aspect ratio, however, has a significant nonlinear impact on boundary layer structure and temperature. Besides, managing rooftop roughness provides an alternative option to change the boundary layer thermal state through modification of the vertical turbulent transport. The sensitivity analysis deepens our insight into the fundamental physics of urban land–atmosphere interactions and provides useful guidance for urban planning under challenges of changing climate and continuous global urbanization.

  17. A characteristic analysis of the fluidic muscle cylinder

    Science.gov (United States)

    Kim, Dong-Soo; Bae, Sang-Kyu; Hong, Sung-In

    2005-12-01

    The fluidic muscle cylinder consists of an air bellows tube, flanges and lock nuts. It's features are softness of material and motion, simplicity of structure, low production cost and high power efficiency. Recently, unlikely the pneumatic cylinder, the fluidic muscle cylinder without air leakage, stick slip, friction, and seal was developed as a new concept actuator. It has the characteristics such as light weight, low price, high response, durable design, long life, high power, high contraction, which is innovative product fulfilling RT(Robot Technology) which is one of the nation-leading next generation strategy technologies 6T as well as cleanness technology. The application fields of the fluidic muscle cylinder are so various like fatigue tester, brake, accelerator, high technology testing device such as driving simulator, precise position, velocity, intelligent servo actuator under special environment such as load controlling system, and intelligent robot. In this study, we carried out the finite element modeling and analysis about the main design variables such as contraction ration and force, diameter increment of fluidic muscle cylinder. On the basis of finite element analysis, the prototype of fluidic muscle cylinder was manufactured and tested. Finally, we compared the results between the test and the finite element analysis.

  18. On the Analysis of Recurrence Characteristics at Variable Actions

    Directory of Open Access Journals (Sweden)

    Horea SANDI

    2011-07-01

    Full Text Available The paper is devoted to some methodological problems raised by the analysis of hazards due to variable actions having implications for the risk of damage to structures. The basic recurrence model used is that of Poissonian stochastic processes. The techniques of calibration of specific recurrence characteristics are discussed, adopting a critical point of view versus statistical analyses relying exclusively on data like annual maxima. The adoption of some types of distributions is critically discussed, from the point of view of their compatibility with the Poissonian model referred to. Only the Gumbel and Fréchet distributions are accepted as adequate for the purpose adopted. Starting from their common properties an unbounded family of distributions is proposed. This family makes it possible to adopt calibrations providing an approximation of unlimited closeness to observation samples. The case of a pluri-dimensional characterization of the randomness of observation data is then tackled, considering as an illustrative case the directional statistical analysis of sequences of wind events. Some specific expressions are proposed for the directional analysis, leading to a good approximation of observation samples. A case study relying on the expressions is then presented.

  19. ANALYSIS OF CAMOUFLAGE COVER SPECTRAL CHARACTERISTICS BY IMAGING SPECTROMETER

    Directory of Open Access Journals (Sweden)

    A. Y. Kouznetsov

    2016-03-01

    Full Text Available Subject of Research.The paper deals with the problems of detection and identification of objects in hyperspectral imagery. The possibility of object type determination by statistical methods is demonstrated. The possibility of spectral image application for its data type identification is considered. Method. Researching was done by means of videospectral equipment for objects detection at "Fregat" substrate. The postprocessing of hyperspectral information was done with the use of math model of pattern recognition system. The vegetation indexes TCHVI (Three-Channel Vegetation Index and NDVI (Normalized Difference Vegetation Index were applied for quality control of object recognition. Neumann-Pearson criterion was offered as a tool for determination of objects differences. Main Results. We have carried out analysis of the spectral characteristics of summer-typecamouflage cover (Germany. We have calculated the density distribution of vegetation indexes. We have obtained statistical characteristics needed for creation of mathematical model for pattern recognition system. We have shown the applicability of vegetation indices for detection of summer camouflage cover on averdure background. We have presented mathematical model of object recognition based on Neumann-Pearson criterion. Practical Relevance. The results may be useful for specialists in the field of hyperspectral data processing for surface state monitoring.

  20. Two-phase flow characteristics analysis code: MINCS

    International Nuclear Information System (INIS)

    Watanabe, Tadashi; Hirano, Masashi; Akimoto, Masayuki; Tanabe, Fumiya; Kohsaka, Atsuo.

    1992-03-01

    Two-phase flow characteristics analysis code: MINCS (Modularized and INtegrated Code System) has been developed to provide a computational tool for analyzing two-phase flow phenomena in one-dimensional ducts. In MINCS, nine types of two-phase flow models-from a basic two-fluid nonequilibrium (2V2T) model to a simple homogeneous equilibrium (1V1T) model-can be used under the same numerical solution method. The numerical technique is based on the implicit finite difference method to enhance the numerical stability. The code structure is highly modularized, so that new constitutive relations and correlations can be easily implemented into the code and hence evaluated. A flow pattern can be fixed regardless of flow conditions, and state equations or steam tables can be selected. It is, therefore, easy to calculate physical or numerical benchmark problems. (author)

  1. Using Dynamic Fourier Analysis to Discriminate Between Seismic Signals from Natural Earthquakes and Mining Explosions

    Directory of Open Access Journals (Sweden)

    Maria C. Mariani

    2017-08-01

    Full Text Available A sequence of intraplate earthquakes occurred in Arizona at the same location where miningexplosions were carried out in previous years. The explosions and some of the earthquakes generatedvery similar seismic signals. In this study Dynamic Fourier Analysis is used for discriminating signalsoriginating from natural earthquakes and mining explosions. Frequency analysis of seismogramsrecorded at regional distances shows that compared with the mining explosions the earthquake signalshave larger amplitudes in the frequency interval ~ 6 to 8 Hz and significantly smaller amplitudes inthe frequency interval ~ 2 to 4 Hz. This type of analysis permits identifying characteristics in theseismograms frequency yielding to detect potentially risky seismic events.

  2. Dynamic characteristics of rotating pretwisted clamped-clamped beam under thermal stress

    International Nuclear Information System (INIS)

    Zhang, Bo; Li, Yueming; Lu, Wei Zhen

    2016-01-01

    Effects of thermal stress on the vibration characteristics, buckling limit and critical speed of a rotating pretwisted beam clamped to rigid hub at a stagger angle were investigated. By considering the work done by thermal stress, the thermal influence on stiffness matrix was introduced in the dynamic model. The motion equations were derived based on Lagrange equation by employing three pure Cartesian deformation variables combined with nonlinear von Karman strain formula. Numerical investigations studied the modal characteristics of the beam. Numerical results calculated from a commercial finite element code and obtained with the present modeling method were in good agreement with the previous results reported in the literature. The combined softening effects due to the thermal stress and the rotation motion were observed. Furthermore, it is shown that the inclusion of thermal stress is necessary for blades operating under a high temperature field. Buckling thermal loads and the critical rotating speed were calculated through solving the corresponding nonlinear equations numerically, and some pertinent conclusions are outlined. It is also found that the peak value position of the first mode shape approaches to the tip of blade with the increment of rotating speed and hub radius. However, the variation in the environment temperature causes only a slight alteration in the mode shape

  3. Dynamic response characteristics of dual flow-path integrally bladed rotors

    Science.gov (United States)

    Beck, Joseph A.; Brown, Jeffrey M.; Scott-Emuakpor, Onome E.; Cross, Charles J.; Slater, Joseph C.

    2015-02-01

    New turbine engine designs requiring secondary flow compression often look to dual flow-path integrally bladed rotors (DFIBRs) since these stages have the ability to perform work on the secondary, or bypassed, flow-field. While analogous to traditional integrally bladed rotor stages, DFIBR designs have many differences that result in unique dynamic response characteristics that must be understood to avoid fatigue. This work investigates these characteristics using reduced-order models (ROMs) that incorporate mistuning through perturbations to blade frequencies. This work provides an alternative to computationally intensive geometric-mistuning approaches for DFIBRs by utilizing tuned blade mode reductions and substructure coupling in cyclic coordinates. Free and forced response results are compared to full finite element model (FEM) solutions to determine if any errors are related to the reduced-order model formulation reduction methods. It is shown that DFIBRs have many more frequency veering regions than their single flow-path integrally blade rotor (IBR) counterparts. Modal families are shown to transition between system, inner-blade, and outer-blade motion. Furthermore, findings illustrate that while mode localization of traditional IBRs is limited to a single or small subset of blades, DFIBRs can have modal energy localized to either an inner- or outer-blade set resulting in many blades responding above tuned levels. Lastly, ROM forced response predictions compare well to full FEM predictions for the two test cases shown.

  4. Dynamic characteristics of rotating pretwisted clamped-clamped beam under thermal stress

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo; Li, Yueming [State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Key Laboratory of Environment and Control for Flight Vehicle, School of Aerospace, Xi' an Jiaotong UniversityXi' an (China); Lu, Wei Zhen [Dept. of Civil and Architectural Engineering, City University of Hong Kong, Hong Kong (China)

    2016-09-15

    Effects of thermal stress on the vibration characteristics, buckling limit and critical speed of a rotating pretwisted beam clamped to rigid hub at a stagger angle were investigated. By considering the work done by thermal stress, the thermal influence on stiffness matrix was introduced in the dynamic model. The motion equations were derived based on Lagrange equation by employing three pure Cartesian deformation variables combined with nonlinear von Karman strain formula. Numerical investigations studied the modal characteristics of the beam. Numerical results calculated from a commercial finite element code and obtained with the present modeling method were in good agreement with the previous results reported in the literature. The combined softening effects due to the thermal stress and the rotation motion were observed. Furthermore, it is shown that the inclusion of thermal stress is necessary for blades operating under a high temperature field. Buckling thermal loads and the critical rotating speed were calculated through solving the corresponding nonlinear equations numerically, and some pertinent conclusions are outlined. It is also found that the peak value position of the first mode shape approaches to the tip of blade with the increment of rotating speed and hub radius. However, the variation in the environment temperature causes only a slight alteration in the mode shape.

  5. Statistical characteristics of dynamics for population migration driven by the economic interests

    Science.gov (United States)

    Huo, Jie; Wang, Xu-Ming; Zhao, Ning; Hao, Rui

    2016-06-01

    Population migration typically occurs under some constraints, which can deeply affect the structure of a society and some other related aspects. Therefore, it is critical to investigate the characteristics of population migration. Data from the China Statistical Yearbook indicate that the regional gross domestic product per capita relates to the population size via a linear or power-law relation. In addition, the distribution of population migration sizes or relative migration strength introduced here is dominated by a shifted power-law relation. To reveal the mechanism that creates the aforementioned distributions, a dynamic model is proposed based on the population migration rule that migration is facilitated by higher financial gains and abated by fewer employment opportunities at the destination, considering the migration cost as a function of the migration distance. The calculated results indicate that the distribution of the relative migration strength is governed by a shifted power-law relation, and that the distribution of migration distances is dominated by a truncated power-law relation. These results suggest the use of a power-law to fit a distribution may be not always suitable. Additionally, from the modeling framework, one can infer that it is the randomness and determinacy that jointly create the scaling characteristics of the distributions. The calculation also demonstrates that the network formed by active nodes, representing the immigration and emigration regions, usually evolves from an ordered state with a non-uniform structure to a disordered state with a uniform structure, which is evidenced by the increasing structural entropy.

  6. Parameter analysis calculation on characteristics of portable FAST reactor

    International Nuclear Information System (INIS)

    Otsubo, Akira; Kowata, Yasuki

    1998-06-01

    In this report, we performed a parameter survey analysis by using the analysis program code STEDFAST (Space, TErrestrial and Deep sea FAST reactor-gas turbine system). Concerning the deep sea fast reactor-gas turbine system, calculations with many variable parameters were performed on the base case of a NaK cooled reactor of 40 kWe. We aimed at total equipment weight and surface area necessary to remove heat from the system as important values of the characteristics of the system. Electric generation power and the material of a pressure hull were specially influential for the weight. The electric generation power, reactor outlet/inlet temperatures, a natural convection heat transfer coefficient of sea water were specially influential for the area. Concerning the space reactor-gas turbine system, the calculations with the variable parameters of compressor inlet temperature, reactor outlet/inlet temperatures and turbine inlet pressure were performed on the base case of a Na cooled reactor of 40 kWe. The first and the second variable parameters were influential for the total equipment weight of the important characteristic of the system. Concerning the terrestrial fast reactor-gas turbine system, the calculations with the variable parameters of heat transferred pipe number in a heat exchanger to produce hot water of 100degC for cogeneration, compressor stage number and the kind of primary coolant material were performed on the base case of a Pb cooled reactor of 100 MWt. In the comparison of calculational results for Pb and Na of primary coolant material, the primary coolant weight flow rate was naturally large for the former case compared with for the latter case because density is very different between them. (J.P.N.)

  7. RG analysis of magnetic catalysis in dynamical symmetry breaking

    International Nuclear Information System (INIS)

    Hong, Deog Ki; Kim, Youngman

    1996-01-01

    We perform the renormalization group analysis on the dynamical symmetry breaking under strong external magnetic field, studied recently by Gusynin, Miransky and Shovkovy. We find that any attractive four-Fermi interaction becomes strong in the low energy, thus leading to dynamical symmetry breaking. When the four-Fermi interaction is absent, the β-function for the electromagnetic coupling vanishes in the leading order in 1/N. By solving the Schwinger-Dyson equation for the fermion propagator, we show that in 1/N expansion, for any electromagnetic coupling, dynamical symmetry breaking occurs due to the presence of Landau energy gap by the external magnetic field. 5 refs

  8. Creation and Reliability Analysis of Vehicle Dynamic Weighing Model

    Directory of Open Access Journals (Sweden)

    Zhi-Ling XU

    2014-08-01

    Full Text Available In this paper, it is modeled by using ADAMS to portable axle load meter of dynamic weighing system, controlling a single variable simulation weighing process, getting the simulation weighing data under the different speed and weight; simultaneously using portable weighing system with the same parameters to achieve the actual measurement, comparative analysis the simulation results under the same conditions, at 30 km/h or less, the simulation value and the measured value do not differ by more than 5 %, it is not only to verify the reliability of dynamic weighing model, but also to create possible for improving algorithm study efficiency by using dynamic weighing model simulation.

  9. Analysis and Modeling of Control Tasks in Dynamic Systems

    DEFF Research Database (Denmark)

    Ursem, Rasmus Kjær; Krink, Thiemo; Jensen, Mikkel Thomas

    2002-01-01

    Most applications of evolutionary algorithms deal with static optimization problems. However, in recent years, there has been a growing interest in time-varying (dynamic) problems, which are typically found in real-world scenarios. One major challenge in this field is the design of realistic test......-case generators (TCGs), which requires a systematic analysis of dynamic optimization tasks. So far, only a few TCGs have been suggested. Our investigation leads to the conclusion that these TCGs are not capable of generating realistic dynamic benchmark tests. The result of our research is the design of a new TCG...

  10. Combinatorial-topological framework for the analysis of global dynamics

    Science.gov (United States)

    Bush, Justin; Gameiro, Marcio; Harker, Shaun; Kokubu, Hiroshi; Mischaikow, Konstantin; Obayashi, Ippei; Pilarczyk, Paweł

    2012-12-01

    We discuss an algorithmic framework based on efficient graph algorithms and algebraic-topological computational tools. The framework is aimed at automatic computation of a database of global dynamics of a given m-parameter semidynamical system with discrete time on a bounded subset of the n-dimensional phase space. We introduce the mathematical background, which is based upon Conley's topological approach to dynamics, describe the algorithms for the analysis of the dynamics using rectangular grids both in phase space and parameter space, and show two sample applications.

  11. Combinatorial-topological framework for the analysis of global dynamics.

    Science.gov (United States)

    Bush, Justin; Gameiro, Marcio; Harker, Shaun; Kokubu, Hiroshi; Mischaikow, Konstantin; Obayashi, Ippei; Pilarczyk, Paweł

    2012-12-01

    We discuss an algorithmic framework based on efficient graph algorithms and algebraic-topological computational tools. The framework is aimed at automatic computation of a database of global dynamics of a given m-parameter semidynamical system with discrete time on a bounded subset of the n-dimensional phase space. We introduce the mathematical background, which is based upon Conley's topological approach to dynamics, describe the algorithms for the analysis of the dynamics using rectangular grids both in phase space and parameter space, and show two sample applications.

  12. Off-road vehicle dynamics analysis, modelling and optimization

    CERN Document Server

    Taghavifar, Hamid

    2017-01-01

    This book deals with the analysis of off-road vehicle dynamics from kinetics and kinematics perspectives and the performance of vehicle traversing over rough and irregular terrain. The authors consider the wheel performance, soil-tire interactions and their interface, tractive performance of the vehicle, ride comfort, stability over maneuvering, transient and steady state conditions of the vehicle traversing, modeling the aforementioned aspects and optimization from energetic and vehicle mobility perspectives. This book brings novel figures for the transient dynamics and original wheel terrain dynamics at on-the-go condition.

  13. Backtracing neutron analysis in the fusion-fission dynamics study

    International Nuclear Information System (INIS)

    Brennand, E. de Goes; Hanappe, F.; Stuttge, L.

    2001-01-01

    A new method for the analysis of multi parametric experimental data is used in the study of the dynamics of the fission process for the compound system 126 Ba. We apply this method to obtain the correlation between thermal energy related to the neutron total multiplicity and the correlation between pre-scission neutron and pos-scission neutron multiplicities. The results obtained are interpreted into the framework of a dynamical model. From this interpretation we have access to the following information: the friction intensity which drives the dynamical evolution of the system; the initial deformation of the compound system; the barrier evolution with temperature and angular momentum, and fission times. (author)

  14. Sensitivity Analysis of Centralized Dynamic Cell Selection

    DEFF Research Database (Denmark)

    Lopez, Victor Fernandez; Alvarez, Beatriz Soret; Pedersen, Klaus I.

    2016-01-01

    and a suboptimal optimization algorithm that nearly achieves the performance of the optimal Hungarian assignment. Moreover, an exhaustive sensitivity analysis with different network and traffic configurations is carried out in order to understand what conditions are more appropriate for the use of the proposed...

  15. Dynamic energy analysis and nuclear power

    International Nuclear Information System (INIS)

    Price, J.

    1974-01-01

    An initial inquiry (intended for the layman) into how the net energy balance of exponential programmes of energy conversion facilities varies in time; what are the energy inputs and outputs of commercial nuclear reactors, both singly and in such programmes; what are the possible errors and omissions in this analysis; and what are the policy and research implications of the results. (author)

  16. Dynamical analysis of critical assembly CC-1

    International Nuclear Information System (INIS)

    Aleman Fernandez, J.R.

    1990-01-01

    The computer code CC-1, elaborated for the analysis of transients in Critical Assemblies is described. The results by the program are compared with the ones presented in the Safety Report for the Critical Assembly of ''La Quebrada'' Nuclear Research Centre (CIN). 7 refs

  17. Dynamic power balance analysis in JET

    International Nuclear Information System (INIS)

    Matthews, G F; Silburn, S A; Challis, C D; Iglesias, D; King, D; Eich, T; Sieglin, B; Contributors, JET

    2017-01-01

    The full scale realisation of nuclear fusion as an energy source requires a detailed understanding of power and energy balance in current experimental devices. In this we explore whether a global power balance model in which some of the calibration factors applied to the source or sink terms are fitted to the data can provide insight into possible causes of any discrepancies in power and energy balance seen in the JET tokamak. We show that the dynamics in the power balance can only be properly reproduced by including the changes in the thermal stored energy which therefore provides an additional opportunity to cross calibrate other terms in the power balance equation. Although the results are inconclusive with respect to the original goal of identifying the source of the discrepancies in the energy balance, we do find that with optimised parameters an extremely good prediction of the total power measured at the outer divertor target can be obtained over a wide range of pulses with time resolution up to ∼25 ms. (paper)

  18. Analysis of biogas compression system dynamics

    International Nuclear Information System (INIS)

    Morini, Mirko; Pinelli, Michele; Venturini, Mauro

    2009-01-01

    The use of biogas for energy production has progressively increased in recent years, due to an increasing interest both in agricultural and energy policies of many industrialized countries. Biogas compression by means of natural gas infrastructure seems the most immediate solution, but could also lead to problems due to the different physical properties of the two gases. In this paper, a non-linear one-dimensional modular dynamic model is developed and used for the simulation of compression system transient behavior. The arrangement consists of a main line, where the compressor operates, and an anti-surge control, which consists of a recycle loop activated by a fast acting valve. Different maneuvers (start-up, normal operation, emergency shutdown and operating point variation) are simulated by using two different working fluids (methane and biogas). Simulations prove that the design of the surge protection system should consider the fluid to be elaborated. Moreover, system predisposition to surge increases as the ratio between system volumes and the inertia of the rotating masses increases.

  19. Transient thermal-hydraulic characteristics analysis software for PWR nuclear power systems

    International Nuclear Information System (INIS)

    Wu Yingwei; Zhuang Chengjun; Su Guanghui; Qiu Suizheng

    2010-01-01

    A point reactor neutron kinetics model, a two-phase drift-flow U-tube steam generator model, an advanced non-equilibrium three regions pressurizer model, and a passive emergency core decay heat-removed system model are adopted in the paper to develop the computerized analysis code for PWR transient thermal-hydraulic characteristics, by Compaq Visual Fortran 6.0 language. Visual input, real-time processing and dynamic visualization output are achieved by Microsoft Visual Studio. NET language. The reliability verification of the soft has been conducted by RELAP 5, and the verification results show that the software is with high calculation precision, high calculation speed, modern interface, luxuriant functions and strong operability. The software was applied to calculate the transient accident conditions for QSNP, and the analysis results are significant to the practical engineering applications. (authors)

  20. Dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle

    International Nuclear Information System (INIS)

    Hassan, H.Z.; Mohamad, A.A.; Al-Ansary, H.A.; Alyousef, Y.M.

    2014-01-01

    The basic SAR (solar-driven adsorption refrigeration) machine is an intermittent cold production system. Recently, the CO-SAR (continuous operation solar-powered adsorption refrigeration) system is developed. The CO-SAR machine is based on the theoretical CTAR (constant temperature adsorption refrigeration) cycle in which the adsorption process takes place at a constant temperature that equals the ambient temperature. Practically, there should be a temperature gradient between the adsorption bed and the surrounding atmosphere to provide a driving potential for heat transfer. In the present study, the dynamic analysis of the CTAR cycle is developed. This analysis provides a comparison between the theoretical and the dynamic operation of the CTAR cycle. The developed dynamic model is based on the D-A adsorption equilibrium equation and the energy and mass balances in the adsorption reactor. Results obtained from the present work demonstrate that, the idealization of the constant temperature adsorption process in the theoretical CTAR cycle is not far from the real situation and can be approached. Furthermore, enhancing the heat transfer between the adsorption bed and the ambient during the bed pre-cooling process helps accelerating the heat rejection process from the adsorption reactor and therefore approaching the isothermal process. - Highlights: • The dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle is developed. • The CTAR theoretical and dynamic cycles are compared. • The dynamic cycle approaches the ideal one by enhancing the bed precooling