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Sample records for dynamic response characteristics

  1. Characteristics of identifying linear dynamic models from impulse response data using Prony analysis

    Energy Technology Data Exchange (ETDEWEB)

    Trudnowski, D.J.

    1992-12-01

    The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general ``rules-of-thumb`` for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

  2. Characteristics of identifying linear dynamic models from impulse response data using Prony analysis

    Energy Technology Data Exchange (ETDEWEB)

    Trudnowski, D.J.

    1992-12-01

    The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general rules-of-thumb'' for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

  3. Application backwards characteristics analysis method to dynamic response of metals under high pressure

    Directory of Open Access Journals (Sweden)

    Pan Hao

    2015-01-01

    Full Text Available Dynamic yield strength of metals/alloys depends on loading pressure and rates sensitively. With the development of laser interferometer measurement system, extracting strength information from window/free surface velocity profiles in shock and ramp loading experiments is becoming an important method to investigate materials’ dynamic response under high pressure and high strain rates. Backwards characteristics analysis method (BCAM can analyze the velocity profiles more reasonable because it accounts for bending of the incoming characteristics due to impedance mismatch between the sample and window. Synthetic analyses of reverse impact experiment and graded-density impactor loading-releasing experiment suggest that BCAM can give more accurate results including sound speed-particle velocity and yield strength at high pressure than incremental impedance matching method. We use BCAM to analyze velocity profiles of Sn in shock-release experiments and obtain its shear modulus and yield strength at different shock pressure and investigate its phase transition and dynamic unloading response.

  4. 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.

  5. DYNAMIC RESPONSE OF ROLLER GEAR INDEXING CAM SYSTEM CONSIDERING CLEARANCE AND MOTOR CHARACTERISTIC

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dynamic responses of roller gear indexing cam mechanism are investigated .With applying Lagarange equation and Gear method,motion equations of this mechanism including clearance,motor characteristic,torsion flexibility are developed and solved.The results show that clearance affects primarily the response on turret,and has little effects on the responses on rotary table.At the same time,the velocity fluctuation of motor shaft is not serious for the existence of inertia of reducer,and the high frequency of velocity fluctuation of camshaft is related with the torsion stiffness of shaft and the clearance between pairs.

  6. Vertical dynamic response characteristics of single pile in non-homogeneous soil layers

    Institute of Scientific and Technical Information of China (English)

    KONG De-sen; LUAN Mao-tian; LING Xian-zhang

    2008-01-01

    A computational method and a mechanical model for evaluating the vertical dynamic harmonic response characteristics of a single pile embedded in non-homogeneous soil layers and subjected to harmonic loadings were established based on a certain assumption and the improved dynamic model of beam-on-Winkler foundation by using the principle of soil dynamics and structure dynamics. Both non-homogeneity of soil strata and softening effect of soil layer around the pile during vibration were simultaneously taken into account in the pro-posed computational model. It is shown through the comparative study on a numerical example that the numerical results of dynamic response of the single pile computed by the proposed method are relatively rational and can well agree with the numerical results computed from the well-known software of finite element method. Finally the parametric studies were conducted for a varied range of main parameters to discuss the effects of relevant factors on dynamic responses of the single pile embedded in non-homogeneous layered soils excited by harmonic loading with different frequencies.

  7. Response and Dynamical Stability of Oscillators with Discontinuous or Steep First Derivative of Restoring Characteristic

    Directory of Open Access Journals (Sweden)

    Željko Božić

    2009-01-01

    Full Text Available Response and dynamical stability of oscillators with discontinuous or steep first derivative of restoring characteristic is considered in this paper. For that purpose, a simple single-degree-of-freedom system with piecewise-linear force-displacement relationship subjected to a harmonic force excitation is analysed by the method of piecing the exact solutions (MPES in the time domain and by the incremental harmonic balance method (IHBM in the frequency domain. The stability of the periodic solutions obtained in the frequency domain by IHBM is estimated by the Floquet-Lyapunov theorem. Obtained frequency response characteristic is very complex and includes multi-frequency response for a single frequency excitation, jump phenomenon, multi-valued and non-periodic solutions. Determining of frequency response characteristic in the time domain by MPES is exceptionally time consuming, particularly inside the frequency ranges of co-existence of multiple stable solutions. In the frequency domain, IHBM is very efficient and very well suited for obtaining wide range frequency response characteristics, parametric studies and bifurcation analysis. On the other hand, neglecting of very small harmonic terms (which in-significantly influence the r.m.s. values of the response and are very small in comparison to other terms of the spectrum can cause very large error in evaluation of the eigenvalues of the monodromy matrix, and so they can lead to incorrect prediction of the dynamical stability of the solution. Moreover, frequency ranges are detected inside which the procedure of evaluation of eigenvalues of the monodromy matrix does not converge with increasing the number of harmonics included in the supposed approximate solution.

  8. Paradoxical response to an emotional task: trait characteristics and heart-rate dynamics.

    Science.gov (United States)

    Balocchi, Rita; Varanini, Maurizio; Paoletti, Giulia; Mecacci, Giulio; Santarcangelo, Enrica 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 detrended fluctuation analysis (DFA). These indices were studied as a function of a few individual characteristics: hypnotizability, gender, absorption, anxiety, and the activity of the behavioral inhibition and activation systems (BIS/BAS). Results showed that (a) the subjective experience of responsiveness is associated with the activity of the behavioral inhibition system and (b) a few RQA and DFA indices are able to capture the influence of cognitive-emotional traits, including hypnotizability, on the responsiveness to the threatening task.

  9. 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.

  10. Nonlinear structural joint model updating based on instantaneous characteristics of dynamic responses

    Science.gov (United States)

    Wang, Zuo-Cai; Xin, Yu; Ren, Wei-Xin

    2016-08-01

    This paper proposes a new nonlinear joint model updating method for shear type structures based on the instantaneous characteristics of the decomposed structural dynamic responses. To obtain an accurate representation of a nonlinear system's dynamics, the nonlinear joint model is described as the nonlinear spring element with bilinear stiffness. The instantaneous frequencies and amplitudes of the decomposed mono-component are first extracted by the analytical mode decomposition (AMD) method. Then, an objective function based on the residuals of the instantaneous frequencies and amplitudes between the experimental structure and the nonlinear model is created for the nonlinear joint model updating. The optimal values of the nonlinear joint model parameters are obtained by minimizing the objective function using the simulated annealing global optimization method. To validate the effectiveness of the proposed method, a single-story shear type structure subjected to earthquake and harmonic excitations is simulated as a numerical example. Then, a beam structure with multiple local nonlinear elements subjected to earthquake excitation is also simulated. The nonlinear beam structure is updated based on the global and local model using the proposed method. The results show that the proposed local nonlinear model updating method is more effective for structures with multiple local nonlinear elements. Finally, the proposed method is verified by the shake table test of a real high voltage switch structure. The accuracy of the proposed method is quantified both in numerical and experimental applications using the defined error indices. Both the numerical and experimental results have shown that the proposed method can effectively update the nonlinear joint model.

  11. Characteristics and dynamic response of 3-D component base isolation system using ball bearings and air springs

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsumi, Hideaki; Yamada, Hiroyuki; Mori, Kazunari; Ebisawa, Katsumi; Shibata, Katsuyuki [Seismic Emergency Information System Research Team, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    2001-02-01

    Introduction of the base isolation technique into the seismic design of nuclear power plant components as well as buildings has been expected as one of effective countermeasure to reduce the seismic force applied to components. A research program on the base isolation of nuclear components has been carried out at the Japan Atomic Energy Research Institute (JAERI) since 1991. A methodology and a computer code (EBISA: Equipment Base Isolation System Analysis) for evaluating the failure frequency of the nuclear component with the base isolation were developed. In addition, a test program, which is concerned with the above development, aiming at improvement of failure frequency analysis models in the code has been conducted since 1996 to investigate the dynamic behavior and to verify the effectiveness of component base isolation systems. Two base isolation test systems with different characteristics were fabricated and static and dynamic characteristics were measured by static loading and free vibration tests. One which consists of ball bearings and air springs was installed on the test bed to observe the dynamic response under natural earthquake motion. The effect of base isolation system has been observed under several earthquakes. Three-dimensional response and effect of base isolation of another system using multi-layer-rubber-bearings and coil springs has been investigated against various large earthquake motions by shaking table test. This report describes the design specification of the base isolation system using ball bearings and air springs, dynamic characteristics, dynamic response against natural seismic motion and results of dynamic response analysis considering the various characteristics of isolation devices. (author)

  12. Dynamic response characteristics of thermoelectric generator predicted by a three-dimensional heat-electricity coupled model

    Science.gov (United States)

    Meng, Jing-Hui; Zhang, Xin-Xin; Wang, Xiao-Dong

    2014-01-01

    The practical application environments of thermoelectric generators (TEGs) always change, which make a requirement for studying the dynamic response characteristics of TEGs. This work develops a complete, three-dimensional and transient model to investigate this issue. The model couples the energy and electric potential equations. Seebeck effect, Peltier effect, Thomson effect, Joule heating and Fourier heat conduction are taken into account in this model. Dynamic output power and conversion efficiency of the TEG, which are caused by variations of the hot end temperature, cold end temperature and load current, are studied. The response hysteresis of the output power to the hot end and cold end temperatures, the overshoot or undershoot of the conversion efficiency are found and attributed to the delay of thermal diffusion. However, the output power is synchronous with the load current due to much faster electric response than thermal response.

  13. Characteristics analysis and dynamic responses of micro-gas-lubricated journal bearings with a new slip model

    Science.gov (United States)

    Zhang, Wen-Ming; Meng, Guang; Huang, Hai; Zhou, Jian-Bin; Chen, Jie-Yu; Chen, Di

    2008-08-01

    In this paper, a new slip model based on kinetic theory of gases for gas-lubricated journal bearings in micro-electro-mechanical systems (MEMS) is applied using a physical approach. The corresponding modified governing equation and mathematic model are presented and the flow rate is plotted versus the inverse Knudsen number. Pressure distributions along the gas bearing at various Knudsen numbers and bearing numbers are plotted and the load carrying capacities are also obtained. A numerical analysis of a rigid rotor supported by gas-lubricated journal bearings is presented for dynamic behaviour. The slip flow effect on the properties, including pressure distribution, load carrying capacity and dynamic coefficients, of the micro-gas-lubricated journal bearings and dynamic responses of the micro rotor-bearing system are estimated and analysed in detail. It is shown that the dynamic coefficients increase with increasing bearing number except for two damping coefficients and the rotor-bearing system runs at a much higher rotating speed to keep stable when slip flow occurs. Moreover, the oscillation period of the rotor operating with the slip model is longer than that with the continuum flow. In addition, the whirl frequency is reduced from 0.422 to 0.079 under the slip effect. Therefore, the results of this study contribute to a further understanding of the characteristics and nonlinear dynamics of gas-film rotor-bearing systems in MEMS.

  14. Turbulent Flow Characteristics and Dynamics Response of a Vertical-Axis Spiral Rotor

    Directory of Open Access Journals (Sweden)

    Yuli Wang

    2013-05-01

    Full Text Available The concept of a vertical-axis spiral wind rotor is proposed and implemented in the interest of adapting it to air flows from all directions and improving the rotor’s performance. A comparative study is performed between the proposed rotor and conventional Savonius rotor. Turbulent flow features near the rotor blades are simulated with Spalart-Allmaras turbulence model. The torque coefficient of the proposed rotor is satisfactory in terms of its magnitude and variation through the rotational cycle. Along the height of the rotor, distinct spatial turbulent flow patterns vary with the upstream air velocity. Subsequent experiments involving a disk generator gives an in-depth understanding of the dynamic response of the proposed rotor under different operation conditions. The optimal tip-speed ratio of the spiral rotor is 0.4–0.5, as is shown in both simulation and experiment. Under normal and relative-motion flow conditions, and within the range of upstream air velocity from 1 to 12 m/s, the output voltage of the generator was monitored and statistically analyzed. It was found that normal air velocity fluctuations lead to a non-synchronous correspondence between upstream air velocity and output voltage. In contrast, the spiral rotor’s performance when operating from the back of a moving truck was significantly different to its performance under the natural conditions.

  15. 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/m(2)) 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.

  16. Dynamic response characteristics of high temperature superconducting maglev systems: Comparison between Halbach-type and normal permanent magnet guideways

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, J., E-mail: jzheng@swjtu.cn [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Che, T. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, B.T.; Si, S.S. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, P R China (China); Deng, Z.G., E-mail: deng@swjtu.cn [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China)

    2015-12-15

    Highlights: • The loading weight affects the RF tremendously. • Reducing the FCH can improve the stability of the maglev vehicle. • The Halbach-type PMG has better loading capacity than the conventional PMG. • Pre-load is an effective way to enhance the dynamic characteristic of the HTS maglev vehicle. - Abstract: The permanent magnet guideway (PMG) is very important for the performance of the high temperature superconducting (HTS) system in terms of electromagnetic force and operational stability. The dynamic response characteristics of a HTS maglev model levitating on two types of PMG, which are the normal PMG with iron flux concentration and Halbach-type PMG, were investigated by experiments. The dynamic signals for different field-cooling heights (FCHs) and loading/unloading processes were acquired and analyzed by a vibration analyzer and laser displacement sensors. The resonant frequency, stiffness and levitation height of the model were discussed. It was found that the maglev model on the Halbach-type PMG has higher resonant frequency and higher vertical stiffness compared with the normal PMG. However, the low lateral stiffness of the model on the Halbach-type PMG indicates poor lateral stability. Besides, the Halbach-type PMG has better loading capacity than the normal PMG. These results are helpful to design a suitable PMG for the HTS system in practical applications.

  17. 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 d

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

    Directory of Open Access Journals (Sweden)

    Jung HH

    2015-10-01

    Full Text Available HoHyun Jung,1 Keyoung Jin Chun,2 Jaesoo Hong,2 Dohyung Lim1 1Department of Mechanical Engineering, Sejong University, Seoul, Republic of Korea; 2Smart Welfare Technology Research Group, Korea Institute of Industrial Technology, Cheonan, Republic of Korea Abstract: 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 (P<0.05. The maximum was greater with anterior–posterior and medial–lateral dynamic rotation than with that in other directions (P<0.05. However, there were no statistically significant differences in the frequency of center of body mass deviations from the base of support (P>0.05. These results

  19. Dynamic characteristics of conveyor belts

    Institute of Scientific and Technical Information of China (English)

    HOU You-fu; MENG Qing-rui

    2008-01-01

    The dynamic characteristics of a belt conveyor are determined to a large extent by the properties of the belt. This paper describes experiments designed to establish the dynamic properties of belting material. The dynamic elastic modulus, viscous damping and theological constants of the belt were measured. Several properties were studied as a function of the tensile loading on the belt. These included longitudinal vibration, the natural vibration frequency in the transverse direction and the response to an impulse excitation. Vibration response was observed under several different excitation frequencies. Most of these properties have not been tested previously under conditions appropriate for the ISO/DP9856 standard. Two types of belt were tested, a steel reinforced belt and a fabric reinforced belt. The test equipment was built to provide data appropriate for designing belt conveyors. It was observed that the stress wave propagation speed increased with tensile load and that tensile load was the main factor influencing longitudinal vibrations.

  20. The dynamic characteristics of the mouse horizontal vestibulo-ocular and optokinetic response

    NARCIS (Netherlands)

    A.M. van Alphen (Arjan); J.S. Stahl (J.); C.I. de Zeeuw (Chris)

    2001-01-01

    textabstractIn the present study the optokinetic reflex, vestibulo-ocular reflex and their interaction were investigated in the mouse, using a modified subconjunctival search coil technique. Gain of the ocular response to sinusoidal optokinetic stimulation was relatively constant for peak velocities

  1. The dynamic characteristics of the mouse horizontal vestibulo-ocular and optokinetic response

    NARCIS (Netherlands)

    A.M. van Alphen (Arjan); J.S. Stahl (J.); C.I. de Zeeuw (Chris)

    2001-01-01

    textabstractIn the present study the optokinetic reflex, vestibulo-ocular reflex and their interaction were investigated in the mouse, using a modified subconjunctival search coil technique. Gain of the ocular response to sinusoidal optokinetic stimulation was relatively constant for peak velocities

  2. Characteristics and dynamic response analysis of 3-D component base isolation system using multi-layer-rubber-bearings and coil springs

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsumi, Hideaki; Yamada, Hiroyuki; Ebisawa, Katsumi; Shibata, Katsuyuki [Seismic Emergency Information System Research Team, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    2000-07-01

    Introduction of the base isolation technique into the seismic design of nuclear power plant components as well as buildings has been expected as one of effective countermeasure to reduce the seismic force applied to components. A research program of the base isolation of nuclear components has been carried out at Japan Atomic Energy Research Institute(JAERI) since 1991. A methodology and a computer code (EBISA: Equipment Base Isolation System Analysis) for evaluating the failure frequency of the nuclear component with the base isolation were developed. In addition, a test program, which is concerned with the above development, i.e., improvement of failure frequency analysis models in the code has been conducted since 1996 to investigate the dynamic behavior and to verify the effectiveness of component base isolation systems. Two kinds of base isolation test systems with different characteristic were fabricated and static and dynamic characteristics were measured by static loading and free vibration tests. One which consists of ball bearings and air springs was installed on the test bed to observe the dynamic response under natural earthquake motion. The effect of base isolation system has been observed under several earthquakes. Another system which consists of multi-layer-rubber-bearings and coil springs has been investigated three-dimensional dynamic behavior and effect of base isolation against various large earthquake motions by shaking table test. This report describes the design specification of the base isolation system which consists of multi-layer-rubber-bearings and coil springs, static and dynamic characteristics, analysis model based on the characteristics, results of shaking table test and the dynamic response analysis (author)

  3. Dynamic characteristics of the cutaneous vasodilator response to a local external pressure application detected by the laser Doppler flowmetry technique on anesthetized rats

    Science.gov (United States)

    Humeau, Anne; Koitka, Audrey; Saumet, Jean-Louis; L'Huillier, Jean-Pierre

    2003-10-01

    The laser Doppler flowmetry technique has recently been used to report a significant transient increase of the cutaneous blood flow signal when a local non-noxious pressure is applied progressively on the skin (11.1 Pa/s). The present work analyses the dynamic characteristics of this vasodilatory reflex response on anaesthetised rats. A de-noising algorithm using wavelets is proposed to obtain accurate values of these dynamic characteristics. The blood flow peak and the time to reach this peak are computed on the de-noised recordings. The results show that the mean time to reach the peak of perfusion is 85.3 s (time t = 0 at the beginning of the pressure application). The mean peak value is 188.3 arbitrary units (a.u.), whereas the mean value of the perfusion before the pressure application is 113.4 a.u. The mean minimum value obtained at the end of the experiment is 60.7 a.u. This latter value is, on the average, reached 841.3 s after the beginning of the pressure application. The comparison of the dynamic characteristics, computed with the de-noising algorithm on signals obtained in other situations, will give a better understanding on some cutaneous lesions such as those present on diabetic people.

  4. Dynamic Response Analysis of Motorized Spindle System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; LUO Yi-chao; XU Juan; XIAO Ru-feng; LI Xian-hui

    2013-01-01

    As to motorized spindle system, this paper builds a simplified 3D model of spindle and bearing, performs structure modal analysis, reveals its dynamic characteristics under the free model;furthermore, modifies bearing radial stiffness and number of model, and studies the change of modal parameters. On this basis, through the harmonic response analysis of the finite element model, dy-namic response characteristic caused by imbalance of monitored spindle system and law of vibration response to different amount of unbalance is analyzed.

  5. Research the dynamical characteristics of slow deformation waves as a rock massif response to explosions during its outworking

    Science.gov (United States)

    Hachay, Olga; Khachay, Oleg; Shipeev, Oleg

    2015-04-01

    As a result of long-term natural geomechanics and geophysical observation data on mines of complex ore rocks, generalization of the non-linear reaction of rock massif to heavy dynamic influences have been established. In addition, pendulum type waves have been observed and the sources of them have been located inside geoblocks of different hierarchic levels (Oparin et al., 2010). At the same time, these waves propagate with wide low (compared with seismic waves) velocity values (Kurlenja et al., 1993; Oparin et al., 2006). Research into the massif state with the use of the dynamic systems theory approach (Naimark et al., 2009; Chulichkov, 2003; Hachay et al., 2010) has been developed to ascertain the criteria of dissipative regimes changing for real rock massifs, which are under heavy man-caused influence. To realize such research we used the data from the seismic record of the Tashtagol mine for the two-year period from June 2006 up to June 2008. We used the space-time coordinates for all dynamic massif event responses, which occurred during that period inside the mine space and for the explosions - values fixed by seismic station energy (Hachay et al., 2010). The phase diagrams of the massif state for the northern and southern parts of the mine space were plotted in coordinates Ev(t) and d(Ev(t))/dt, t - time - in parts of 24 hours, Ev - the dissipated massive seismic energy - in joules. Hachay et al., (2010) analysed the morphology of seismic response phase trajectories on the explosion influences during different serial intervals in the southern part of the mine. In that period, according to data for different explosions in the mine, the majority of the total energy had been injected into the southern part of the mine. Moreover, at the end of 2007, just in the southern part, the strongest rock burst during the whole history of the working mine happened. We developed a new processing method of seismological information in real, which we can use directly in the

  6. Dynamic characteristics of laser Doppler flowmetry signals obtained in response to a local and progressive pressure applied on diabetic and healthy subjects

    Science.gov (United States)

    Humeau, Anne; Koitka, Audrey; Abraham, Pierre; Saumet, Jean-Louis; L'Huillier, Jean-Pierre

    2004-09-01

    In the biomedical field, the laser Doppler flowmetry (LDF) technique is a non-invasive method to monitor skin perfusion. On the skin of healthy humans, LDF signals present a significant transient increase in response to a local and progressive pressure application. This vasodilatory reflex response may have important implications for cutaneous pathologies involved in various neurological diseases and in the pathophysiology of decubitus ulcers. The present work analyses the dynamic characteristics of these signals on young type 1 diabetic patients, and on healthy age-matched subjects. To obtain accurate dynamic characteristic values, a de-noising wavelet-based algorithm is first applied to LDF signals. All the de-noised signals are then normalised to the same value. The blood flow peak and the time to reach this peak are then calculated on each computed signal. The results show that a large vasodilation is present on signals of healthy subjects. The mean peak occurs at a pressure of 3.2 kPa approximately. However, a vasodilation of limited amplitude appears on type 1 diabetic patients. The maximum value is visualised, on the average, when the pressure is 1.1 kPa. The inability for diabetic patients to increase largely their cutaneous blood flow may bring explanations to foot ulcers.

  7. Dynamic normal forms and dynamic characteristic polynomial

    DEFF Research Database (Denmark)

    Frandsen, Gudmund Skovbjerg; Sankowski, Piotr

    2011-01-01

    with relative error 2−b in additional O(nlog2nlogb) time. Furthermore, it can be used to dynamically maintain the singular value decomposition (SVD) of a generic matrix. Together with the algorithm, the hardness of the problem is studied. For the symmetric case, we present an Ω(n2) lower bound for rank...

  8. The dynamic response of a hot-wire anemometer: IV. Sine-wave voltage perturbation testing for near-wall hot-wire/film probes and the presence of low-high frequency response characteristics

    Science.gov (United States)

    Teo, C. J.; Khoo, B. C.; Teo, C. J.; Chew, Y. T.

    2001-01-01

    Experiments were performed using the electronic sine-wave voltage-perturbation test to systematically study the frequency responses of near-wall hot-wire probes subjected in turn to varying magnitudes of convective velocity and different effects of wall influence. In addition, quartz-substrate hot-film gauges with various thicknesses of quartz coating were also investigated. Results of the high cut-off frequency obtained using the sine-wave test (fsine) were found to be in fair agreement with those obtained using the square-wave test (fS) both for hot-wire and for hot-film sensors. The sine-wave test response curve exhibited a distinct bulging effect for the hot-film gauges. For the hot-wire sensors, a much weaker bulging effect was also observed. In contrast to fS and fsine, the low frequency response characteristic corresponding to the location of the bulging effect (fbulge) compared much more favourably with the dynamic frequency response (fD) obtained by Khoo et al and Chew et al using a known near-wall fluctuating flow field. Freymuth's theory for non-cylindrical hot-film sensors incorporating the Bellhouse-Schultz model was applied to predict the responses of the hot-film wall gauges when they were subjected to electronic sine-wave testing and dynamic perturbation testing under different parametric conditions. Although it is one-dimensional in nature, the model is capable of predicting most of the trends observed in the present study and previous works by Khoo et al (1998a) and Chew et al (1998a).

  9. Chaos dynamic characteristics during mine fires

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Mine fires break out and continue in confmed scopes, studying mine fire dynamics characteristics is very usefulto prevent and control fire. The judgement index of fire chaos characteristics was introduced, chaos analysis of mine Fireprocess was described, and the reconstruction of phase space was also presented. An example of mine fire was calculated.The computations show that it is feasible to analyze mine fire dynamic characteristics with chaos theory, and indicate thatfire preoeas is a catastrophe, that is to say, the fire system changes from one state to another during mine fire

  10. Dynamic characteristics of peripheral jet ACV. II - Pitching motion

    Science.gov (United States)

    Mori, T.; Maeda, H.

    The dynamic pitching characteristics of peripheral jet ACV (Air Cushion Vehicle) which have a stability curtain are investigated analytically and experimentally. The measured values of moment, lift and cushion pressure are compared with numerical results noting applicability to the pitching motion. The response of ACV to the sinusoidal pitching oscillation of the ground is also studied.

  11. Dynamic characteristics of NC table with SVD

    Institute of Scientific and Technical Information of China (English)

    Linhong WANG; Bo WU; Runsheng DU; Shuzi YANG

    2008-01-01

    This paper employs the SVD (singular value decomposition) method to study dynamic characteristics of a numerical control (NC) table. Acceleration signals of the NC table at three directions are tested; the singular spectrum of the signals is acquired with SVD; principal components of the signals are found out; dynamic char-acteristics of the signals and their contributing factors are studied by extracting dynamic characteristics of principal components; and signals and principal components are quantitatively analyzed by calculating signal energy. Results indicate that signal characteristics of the previous two principal components are apparent, based on which dynamic characteristics of chaotic signal can be extracted. Signal at the perpendicular direction of the table is signifi-cantly correlated with that at the horizontal motion dir-ection, which indicates that they are excited from the same vibration source. However, signals perpendicular to each other in terms of the motion direction at the horizontal level are rarely correlated; the total signal energy is max-imum at the motion direction, minimum at the horizontal non-motion direction, and medium at the perpendicular non-motion direction. Bending vibration of the lead screw at the perpendicular direction is far more violent than that at the horizontal direction.

  12. 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...

  13. Modeling and Dynamic Response Characteristics Analysis of High-Speed Solenoid Valve Based on Test Data%基于试验数据的高速电磁阀建模及动态响应特性分析

    Institute of Scientific and Technical Information of China (English)

    李汝宁; 高怡; 吕帆; 李华乐; 徐春龙; 赵中余

    2016-01-01

    高速电磁阀的响应特性对高压共轨喷油器的喷油特性具有决定性影响。为了更合理和准确地预测高速电磁阀的电磁特性,基于高速电磁阀理论分析,进行了大量不同驱动电流强度和气隙情况下的电磁力试验,采用多项式拟合的方法,对试验数据进行拟合,结合高速电磁阀的工作原理,应用Amesim软件建立高速电磁阀一维仿真模型,并研究分析了驱动电流、阀芯弹簧预紧力和刚度对高速电磁阀动态响应特性的影响。研究结果表明:所采用的基于试验数据的高速电磁阀建模方式为其动态响应特性的研究提供了一个新思路,它能快速、准确得到高速电磁阀各参数对其响应特性的影响。%The dynamic response characteristics of high‐speed solenoid valve had a critical influence on injection characteristics of high‐pressure common‐rail injector .In order to predict the electromagnetic characteristics of high‐speed solenoid valve more accurately ,a great deal of electromagnetic force tests under the conditions of different current intensities and air gaps were car‐ried out based on theoretical analysis of high‐speed solenoid valve ,the test data were fitted with the polynomial fitting method , and finally one‐dimensional simulation model of high‐speed solenoid valve was built with AMEsim software according to the working principles of high‐speed solenoid valve .Then the influences of three parameters such as drive current ,preload and elas‐tic strength of valve element spring on the dynamic response characteristics of high‐speed solenoid valve were studied .The re‐sults show that the modeling method based on test data offers a new idea to study the dynamic response characteristics of high‐speed solenoid valve ,w hich can acquire the influences of each parameter on the dynamic response characteristics fast and accu‐rately .

  14. Nonlinear Dynamic Characteristics of Oil-in-Water Emulsions

    Science.gov (United States)

    Yin, Zhaoqi; Han, Yunfeng; Ren, Yingyu; Yang, Qiuyi; Jin, Ningde

    2016-08-01

    In this article, the nonlinear dynamic characteristics of oil-in-water emulsions under the addition of surfactant were experimentally investigated. Firstly, based on the vertical upward oil-water two-phase flow experiment in 20 mm inner diameter (ID) testing pipe, dynamic response signals of oil-in-water emulsions were recorded using vertical multiple electrode array (VMEA) sensor. Afterwards, the recurrence plot (RP) algorithm and multi-scale weighted complexity entropy causality plane (MS-WCECP) were employed to analyse the nonlinear characteristics of the signals. The results show that the certainty is decreasing and the randomness is increasing with the increment of surfactant concentration. This article provides a novel method for revealing the nonlinear dynamic characteristics, complexity, and randomness of oil-in-water emulsions with experimental measurement signals.

  15. 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.

  16. 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.

  17. Dynamical response of vibrating ferromagnets

    CERN Document Server

    Gaganidze, E; Ziese, M

    2000-01-01

    The resonance frequency of vibrating ferromagnetic reeds in a homogeneous magnetic field can be substantially modified by intrinsic and extrinsic field-related contributions. Searching for the physical reasons of the field-induced resonance frequency change and to study the influence of the spin glass state on it, we have measured the low-temperature magnetoelastic behavior and the dynamical response of vibrating amorphous and polycrystalline ferromagnetic ribbons. We show that the magnetoelastic properties depend strongly on the direction of the applied magnetic field. The influence of the re-entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the main area of the samples the behavior of ferromagnetic reeds is rather independent of the material composition and magnetic state, exhibiting a large decrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of t...

  18. Distributed Dynamic Condition Response Structures

    DEFF Research Database (Denmark)

    Hildebrandt, Thomas; Mukkamala, Raghava Rao

    We present distributed dynamic condition response structures as a declarative process model inspired by the workflow language employed by our industrial partner and conservatively generalizing labelled event structures. The model adds to event structures the possibility to 1) finitely specify...... repeated, possibly infinite behavior, 2) finitely specify fine-grained acceptance conditions for (possibly infinite) runs based on the notion of responses and 3) distribute events via roles. We give a graphical notation inspired by related work by van der Aalst et al and formalize the execution semantics...

  19. The Dynamic Responsiveness of Organizations

    DEFF Research Database (Denmark)

    Andersen, Torben Juul

    Organizational studies should address contemporary challenges of dealing effectively with the increasingly complex and dynamic business conditions. In this context we argue that structural features are linked to the corporate strategy process and affect the organization’s ability to respond...... to ongoing environmental changes. Sustainable performance arguably derives from integrative strategy-making where business opportunities are pursued as they emerge while being directed and coordinated through forward-looking analytics. This combination of decentralized responsiveness and central reasoning...

  20. MATRIX ALGEBRA ALGORITHM OF STRUCTURE RANDOM RESPONSE NUMERICAL CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new algorithm of structure random response numerical characteristics, named as matrix algebra algorithm of structure analysis is presented.Using the algorithm, structure random response numerical characteristics can easily be got by directly solving linear matrix equations rather than structure motion differential equations.Moreover, in order to solve the corresponding linear matrix equations, the numerical integration fast algorithm is presented.Then according to the results, dynamic design and life-span estimation can be done.Besides, the new algorithm can solve non-proportion damp structure response.

  1. Dynamic response of visco-elastic plates

    Science.gov (United States)

    Kadıoǧlu, Fethi; Tekin, Gülçin

    2016-12-01

    In this study, a comprehensive analysis about the dynamic response characteristics of visco-elastic plates is given. To construct the functional in the Laplace-Carson domain for the analysis of visco-elastic plates based on the Kirchhoff hypothesis, functional analysis method is employed. By using this new energy functional in the Laplace-Carson domain, moment values that are important for engineers can be obtained directly with excellent accuracy and element equations can be written explicitly. Three-element model is considered for modelling the visco-elastic material behavior. The solutions obtained in the Laplace-Carson domain by utilizing mixed finite element formulation are transformed to the time domain using the Durbin's inverse Laplace transform technique. The proposed mixed finite element formulation is shown to be simple to implement and gives satisfactory results for dynamic response of visco-elastic plates.

  2. Dynamic characteristics of large repetitive framelike structures

    Science.gov (United States)

    Nayfeh, A. H.; Hartle, M. S.

    1984-01-01

    Using a building block approach and starting with a single element, expressions for the energy of various two-dimensional frametype gridwork configurations are derived. These are then used to develop energy equivalent continua for the gridworks. Equations of motion and associated boundary conditions are obtained for the continua. Some dynamic characteristics of these continua are investigated and compared with corresponding results obtained from finite element codes and also with some available theoretical predictions.

  3. Dynamic Characteristics of Explicit Control Protocol

    Institute of Scientific and Technical Information of China (English)

    CHENG Shuang-mei; LI Jian-hua; GUO Chuan-xiong

    2008-01-01

    The dynamic characteristics of eplicit control protocol (XCP) were investigated with single bottle-neck on the microscopic time-scale. Analysis and simulation results show that the bandwidth utilization of an XCP bottleneck link converges to 1 at exponential rate, persistent congestion cannot occur at the bottleneck link, and throughput of an arbitrary subset of XCP flows at the bottleneck link converges to its fair share in exponential rate. The XCP has high bandwidth utilization and good fairness properties.

  4. Dynamic response of cavitating turbomachines

    Science.gov (United States)

    Ng, S. L.

    1976-01-01

    Stimulated by the pogo instability encountered in many liquid propellant rockets, the dynamic behavior of cavitating inducers is discussed. An experimental facility where the upstream and downstream flows of a cavitating inducer could be perturbed was constructed and tested. The upstream and downstream pressure and mass flow fluctuations were measured. Matrices representing the transfer functions across the inducer pump were calculated from these measurements and from the hydraulic system characteristics for two impellers in various states of cavitation. The transfer matrices when plotted against the perturbing frequency showed significant departure from steady state or quasi-steady predictions especially at higher frequencies.

  5. On the Dynamic Measurements of Hydraulic Characteristics

    Science.gov (United States)

    Hasmatuchi, Vlad; Bosioc, Alin; Münch-Alligné, Cécile

    2016-11-01

    The present work introduces the implementation and validation of a faster method to measure experimentally the efficiency characteristics of hydraulic turbomachines at a model scale on a test rig. The case study is represented by a laboratory prototype of an in-line axial microturbine for water supply networks. The 2.65 kW one-stage variable speed turbine, composed by one upstream 5-blade runner followed by one counter-rotating downstream 7-blade runner, has been installed on the HES-SO Valais/Wallis universal test rig dedicated to assess performances of small hydraulic machinery following the IEC standard recommendations. In addition to the existing acquisition/control system of the test rig used to measure the 3D hill-chart of a turbine by classical static point-by-point method, a second digitizer has been added to acquire synchronized dynamic signals of the employed sensors. The optimal acceleration/deceleration ramps of the electrical drives have been previously identified in order to cope with the purpose of a reduced measurement time while avoiding errors and hysteresis on the acquired hydraulic characteristics. Finally, the comparison between the turbine efficiency hill-charts obtained by dynamic and static point-by-point methods shows a very good agreement in terms of precision and repeatability. Moreover, the applied dynamic method reduces significantly (by a factor of up to ten) the time necessary to measure the efficiency characteristics on model testing.

  6. Dynamic Characteristics of Electrostatically Actuated Shape Optimized Variable Geometry Microbeam

    Directory of Open Access Journals (Sweden)

    Sha Zhang

    2015-01-01

    Full Text Available We mainly analyze the dynamic characteristics of electrostatically actuated shape optimized variable geometry microbeam. A nonlinear dynamic model considering midplane stretching, electrostatic force, and electrical field fringing effects is developed. Firstly, we study the static responses of the optimized microbeams under DC polarization voltage. The generalized differential quadrature method (GDQM is used. Secondly, the dynamic responses of the shape optimized microbeams driven by DC and AC voltages are investigated using GDQM in conjunction with Levenberg-Marquardt optimization method. The results show that the more gradual change in width, the larger the resonant frequency and the maximum amplitude at resonance. Then we further discuss in detail how do the maximum width, midsection width, and curvature of the width function affect the frequency response of the microbeams. We find that the amplitude and resonant frequency of the dynamic response are not monotonically increasing as the curvature of the width function increases and there exists a critical curvature. This analysis will be helpful in the optimal design of MEMS actuators. Finally, for more consideration, different residual stress, squeeze-film damping, and fringing effect models are introduced into the governing equation of motion and we compare the corresponding dynamic response.

  7. Dynamic Metabolism in Immune Response

    Science.gov (United States)

    Al-Hommrani, Mazen; Chakraborty, Paramita; Chatterjee, Shilpak; Mehrotra, Shikhar

    2016-01-01

    Cell, the basic unit of life depends for its survival on nutrients and thereby energy to perform its physiological function. Cells of lymphoid and myeloid origin are key in evoking an immune response against “self” or “non-self” antigens. The thymus derived lymphoid cells called T cells are a heterogenous group with distinct phenotypic and molecular signatures that have been shown to respond against an infection (bacterial, viral, protozoan) or cancer. Recent studies have unearthed the key differences in energy metabolism between the various T cell subsets, natural killer cells, dendritic cells, macrophages and myeloid derived suppressor cells. While a number of groups are dwelling into the nuances of the metabolism and its role in immune response at various strata, this review focuses on dynamic state of metabolism that is operational within various cellular compartments that interact to mount an effective immune response to alleviate disease state.

  8. Experimental research of a temperature prediction method based on the dynamic response characteristics of thermocouple%基于热电偶动态特性的温度预估方法实验研究

    Institute of Scientific and Technical Information of China (English)

    成红刚; 陈雄; 鞠玉涛; 周长省; 朱国强

    2012-01-01

    针对高温高频和非均匀热流密度条件下温度测量问题,采用激光连续加热热电偶的方法,研究了不同热流密度条件下、不同直径热电偶的动态响应特性,分析了热流密度对热电偶动态响应时间和电压变化率的影响,得到热电偶动态响应时间、电压变化率与热流密度的函数关系,并提出了一种基于热电偶动态响应特性温度预估方法.结果表明:热电偶动态特性受热流密度影响较大,在相同热流密度条件下,动态响应时间与电压变化率的指数函数呈线性关系;文中提出的温度预估方法在超出热电偶测温量程27.3%的范围内具有较小误差,能满足工程温度测量的需要.%Aimed at temperature measurement under high-temperature, high-frequency and non-uniform heat fluxes, the method of continuously heating the thermocouples by laser was adopted to study the dynamic response characteristics of thermocouples with different diameters under different heat fluxes. The effects of heat flux on thermocouple response time and voltage regulation factor were analyzed and the functions of the response time and voltage regulation factor with heat flux were obtained, and then a temperature prediction method based on dynamic response characteristics of thermocouples was presented. The results show that the dynamic response characteristics of thermocouples is greatly affected by heat flux, under the same heat flux, the response time exhibits linear relation with the exponent function of the voltage regulation factor;the temperature prediction method shows a small error when temperature exceeds 27. 3% of the measuring range of the thermocouple and is able to meet the needs of engineering temperature measurements.

  9. Nested Dynamic Condition Response Graphs

    DEFF Research Database (Denmark)

    Hildebrandt, Thomas; Mukkamala, Raghava Rao; Slaats, Tijs

    2012-01-01

    We present an extension of the recently introduced declarative process model Dynamic Condition Response Graphs ( DCR Graphs) to allow nested subgraphs and a new milestone relation between events. The extension was developed during a case study carried out jointly with our industrial partner...... Exformatics, a danish provider of case and workflow management systems. We formalize the semantics by giving first a map from Nested to (flat) DCR Graphs with milestones, and then extending the previously given mapping from DCR Graphs to Buchi-automata to include the milestone relation....

  10. Dynamic characteristics of spring sandstorms in 2000

    Institute of Scientific and Technical Information of China (English)

    周秀骥; 徐祥德; 颜鹏; 翁永辉; 王建林

    2002-01-01

    Systematical analyses of spring sandstorms in 2000 affecting Beijing area are carried out. Results revealed the key dynamic mechanisms of dust storm during its mobilization, lifting, horizontal advection and deposition processes. It turns out that in the processes of sandstorms influencing Beijing area in March-April 2000, the dynamic conditions for dust mobilization are significantly correlated with phenomena, such as cold air-related climatic activities,clay soils area of North China and surface friction velocity anomaly. The characteristics of sandstorm can be described by composite mode of dust particles mobilization-lifting-long-range transport. This paper will provide scientific evidences for further studies,prediction and harness of sandstorms in China.

  11. Dynamical response of vibrating ferromagnets

    Science.gov (United States)

    Gaganidze, E.; Esquinazi, P.; Ziese, M.

    2000-02-01

    The resonance frequency of vibrating ferromagnetic reeds in a homogeneous magnetic field can be substantially modified by intrinsic and extrinsic field-related contributions. Searching for the physical reasons of the field-induced resonance frequency change and to study the influence of the spin glass state on it, we have measured the low-temperature magnetoelastic behavior and the dynamical response of vibrating amorphous and polycrystalline ferromagnetic ribbons. We show that the magnetoelastic properties depend strongly on the direction of the applied magnetic field. The influence of the re-entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the main area of the samples the behavior of ferromagnetic reeds is rather independent of the material composition and magnetic state, exhibiting a large decrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of the reed and the magnetomechanical pole effect within a domain rotation model and is not related to magnetoelasticity.

  12. Dynamic response of flexible retaining walls

    Energy Technology Data Exchange (ETDEWEB)

    Younan, A.H.; Veletsos, A.S.; Bandyopadhyay, K.

    1997-01-01

    Making use of an extension of a recently proposed, relatively simple, approximate method of analysis, a critical evaluation is made of the response to horizontal ground shaking of flexible walls retaining a uniform, linear, viscoelastic stratum of constant thickness and semiinfinite extent in the horizontal direction. Both cantilever and top-supported walls are examined. Following a detailed description of the method and of its rate of convergence, comprehensive numerical solutions are presented that elucidate the action of the system and the effects of the various parameters involved. The parameters varied include the flexibility of the wall, the condition of top support, and the characteristics of the ground motion. The effects of both harmonic base motions and an actual earthquake record are examined. Special attention is paid to the effects of long-period, effectively static excitations. A maximum dynamic response is then expressed as the product of the corresponding static response and an appropriate amplification or deamplification factor. The response quantities examined include the displacements of the wall relative to the moving base, the dynamic wall pressures, and the total wall force, base shear and base moment.

  13. Simulation and Analysis of Dynamic Characteristics of3D Assembly Circuit Module with Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    黄春跃; 周德俭; 黄红艳

    2004-01-01

    Based on the modal analysis theory and by using the dynamics finite element analysis model of a three-dimensional assembly circuit module, dynamic characteristics of circuit module have been studied, including both natural characteristics analysis and dynamic responses analysis. Using a subspace method, modal analysis is first carried out. The first 6 orders of natural frequencies and vibration modes are obtained. Influence of the number of the Z-shaped metal slices on dynamic characteristics of the entire structure is also studied.Harmonic response analysis is then conducted. The steady-state response when the circuit module is subjected to harmonic excitation is determined. A curve of the response values against frequencies is obtained. As a result, the optimal number of Z-shaped metal slices can be determined, and it can be assured that the three-dimensional assembly circuit module has good performance in terms of the dynamic characteristics.

  14. The experimental investigation of bounce characteristics of ACV responsive skirt

    Science.gov (United States)

    Zhou, W. L.; Ma, T.

    This paper presents some experimental results on the bounce characteristics of the bag-finger responsive skirt and on skirt frequency response under cushion pressure excitation obtained in a large-scale box facility. The influence of some parameters on the amplitude and frequency of the skirt bounce motion and the amplitude of the cushion pressure oscillation were explored, and the corresponding bounce boundary curves are given. Some interesting nonlinear phenomena related to the skirt instability in the time domain response are presented. The mechanism for skirt bounce and the important parameters affecting skirt dynamic stability are examined, and some means for eliminating skirt bounce are introduced.

  15. THEORETICAL MODEL AND NUMERICAL METHOD ON ONLINE IDENTIFICATION OF DYNAMICAL CHARACTERISTICS OF STRUCTURAL SYSTEM

    Institute of Scientific and Technical Information of China (English)

    姚志远; 汪凤泉

    2004-01-01

    An online method of identification of dynamic characteristics only using measured ambient response of structural dynamic system is widely focused on. The Ibrahim and ARMA (AutoRegressive Moving Average ) methods are basic identification methods. A model on dynamic system suffered by random ambient excitation was researched into, and a subspace decomposition method being different from traditional harmonic retrieval method was introduced. Robustness and effectiveness of this approach on identification of vibration characteristics are demonstrated on numerical experiment.

  16. 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.

  17. Analyses of dynamic characteristics and seismic response spectrum of pedestrian steel truss bridge%人行钢桁架桥动力特性及反应谱分析

    Institute of Scientific and Technical Information of China (English)

    何钰龙; 李超; 申杨凡; 孟庆超

    2015-01-01

    In order to study the characteristics of pedestrian steel truss bridge vibration and dynamic response under seismic action ,a finite element model of the bridge is built by ANSYS to conduct modal analysis and response spectrum analysis ,and the peak value responds of displacement at key sections are obtained .The results indicate that pedestrian steel truss bridge is more susceptible to vibration than railway truss bridge ,and the torsion deformation appears earlier ;pedestrian steel truss bridge is prone to the horizontal and vertical displacement ,and the mid‐span displacement response is larger with the top chord of displacement response than the lower chord large in seismic response spectrum .The conclusions can provide the reference basis for the seismic design of pedestrian steel truss bridge .%为研究人行钢桁架桥动力特性及在地震作用下的动力响应,运用ANSYS对某人行钢桁架桥进行模态分析,用反应谱分析法对其进行三向激励地震响应分析,得到关键截面及桁架杆件的动力响应。分析结果表明:人行钢桁架桥较铁路钢桁架桥更易发生振动,且扭转变形出现较早;在地震反应谱作用下,人行钢桁架桥较易出现横向及竖向位移,且跨中位移响应较大,上弦杆位移响应较下弦杆大。

  18. Aluminum Honeycomb Characteristics in Dynamic Crush Environments

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, Vesta I.; Swanson, Lloyd H.

    1999-07-01

    Fifteen aluminum honeycomb cubes (3 in.) have been crushed in the Mechanical Shock Laboratory's drop table testing machines. This report summarizes shock experiments with honeycomb densities of 22.1 pcf and 38.0 pcf and with crush weights of 45 lb, 168 lb, and 268 lb. The honeycomb samples were crushed in all three orientations, W, L, and T. Most of the experiments were conducted at an impact velocity of {approx}40 fps, but higher velocities of up to 90 fps were used for selected experiments. Where possible, multiple experiments were conducted for a specific orientation and density of the honeycomb samples. All results are for Hexcel honeycomb except for one experiment with Alcore honeycomb and have been evaluated for validity. This report contains the raw acceleration data measured on the top of the drop table carriage, pictures of the crushed samples, and normalized force-displacement curves for all fifteen experiments. These data are not strictly valid for material characteristics in L and T orientations because the cross-sectional area of the honeycomb changed (split) during the crush. However, these are the best data available at this time. These dynamic crush data do suggest a significant increase in crush strength to 8000 psi ({approximately} 25-30% increase) over quasi-static values of {approximately}6000 psi for the 38.0 pcf Hexcel Honeycomb in the T-orientation. An uncertainty analysis is included and estimates the error in these data.

  19. Varying Load Incentive Dynamics Model and Response Characteristic of Planetary Gear System of Wind Turbine%风电行星齿轮系统变载荷激励动力学模型及其响应特性

    Institute of Scientific and Technical Information of China (English)

    杨军; 张浬萍

    2013-01-01

    According to the characteristics of varying load and varying speed of the planetary gear system of a wind turbine,the dynamics model of the planetary gear system under varying load was proposed and the differential equation of system motion was obtained by analyzing the forces of components with rigid body or elastic body and applying theory of the composite motion.On the basis of these,the mechanism of influence of the internal and external incentive on dynamic load and dynamic factor of planetary gear system was analyzed.Taking a typical MW planetary gear system of wind turbine as an example,the dynamic response characteristics were simulated and analyzed,the results show that the time—varying mesh stiffness of gear pairs and the time—varying stiffness of bearing affect the size of response frequency,the low frequency components are found in response frequencies and energy allocation of various order frequencies is also influenced because of the external loads.The research results lay a foundation for dynamic optimization design and life analysis of wind turbine gearbox.%针对风电行星齿轮系统变载变速的运行特点,通过分析系统构件为刚体和弹性体时的受力情况,应用运动合成原理,提出了变载荷激励下行星齿轮系统动力学模型的建立方法,并推导出系统的运动微分方程.在此基础上,分析了行星齿轮系统的内外部激励因素及其对系统动载荷和动载系数的影响机理.计算并分析了某MW级风电行星齿轮系统的动态响应,结果表明:系统的时变啮合刚度和时变轴承刚度主要影响响应频率的数值大小和系统的振动能量;外部变载荷使响应频率中存在明显的低频成分,并影响各阶振动间的能量分配;齿轮啮合力的动载系数主要受到外部变载荷的影响,而轴承力的动载系数同时受到系统内部激励和外部激励的影响.研究结果为风电齿轮箱的疲劳寿命分析和动态优化设计奠定了基础.

  20. Eccentric Exercise: Physiological Characteristics and Acute Responses.

    Science.gov (United States)

    Douglas, Jamie; Pearson, Simon; Ross, Angus; McGuigan, Mike

    2017-04-01

    An eccentric contraction involves the active lengthening of muscle under an external load. The molecular and neural mechanisms underpinning eccentric contractions differ from those of concentric and isometric contractions and remain less understood. A number of molecular theories have been put forth to explain the unexplained observations during eccentric contractions that deviate from the predictions of the established theories of muscle contraction. Postulated mechanisms include a strain-induced modulation of actin-myosin interactions at the level of the cross-bridge, the activation of the structural protein titin, and the winding of titin on actin. Accordingly, neural strategies controlling eccentric contractions also differ with a greater, and possibly distinct, cortical activation observed despite an apparently lower activation at the level of the motor unit. The characteristics of eccentric contractions are associated with several acute physiological responses to eccentrically-emphasised exercise. Differences in neuromuscular, metabolic, hormonal and anabolic signalling responses during, and following, an eccentric exercise bout have frequently been observed in comparison to concentric exercise. Subsequently, the high levels of muscular strain with such exercise can induce muscle damage which is rarely observed with other contraction types. The net result of these eccentric contraction characteristics and responses appears to be a novel adaptive signal within the neuromuscular system.

  1. 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

  2. DYNAMICS OF THE ESCAPE RESPONSE.

    Science.gov (United States)

    requirements. It has been shown that force is a lawful response measure under positive reinforcement (Notterman and Mintz, 1965). Subjects will adjust...concluded that response force in an escape situation is a lawful response measure, and that it operates in a manner similar to force under positive reinforcement .

  3. Morphological characteristics of motile plants for dynamic motion

    Science.gov (United States)

    Song, Kahye; Yeom, Eunseop; Kim, Kiwoong; Lee, Sang Joon

    2014-11-01

    Most plants have been considered as non-motile organisms. However, plants move in response to environmental changes for survival. In addition, some species drive dynamic motions in a short period of time. Mimosa pudica is a plant that rapidly shrinks its body in response to external stimuli. It has specialized organs that are omnidirectionally activated due to morphological features. In addition, scales of pinecone open or close up depending on humidity for efficient seed release. A number of previous studies on the dynamic motion of plants have been investigated in a biochemical point of view. In this study, the morphological characteristics of those motile organs were investigated by using X-ray CT and micro-imaging techniques. The results show that the dynamic motions of motile plants are supported by structural features related with water transport. These studies would provide new insight for better understanding the moving mechanism of motile plant in morphological point of view. This research was financially supported by the Creative Research Initiative of the Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of Korea (Grant Number: 2008-0061991).

  4. Dynamical response to a stationary tidal field

    CERN Document Server

    Landry, Philippe

    2015-01-01

    We demonstrate that a slowly rotating compact body subjected to a stationary tidal field undergoes a dynamical response, in which the fluid variables and the interior metric vary on the time scale of the rotation period. This dynamical response requires the tidal field to have a gravitomagnetic component generated by external mass currents; the response to a gravitoelectric tidal field is stationary. We confirm that in a calculation carried out to first order in the body's rotation, the exterior geometry bears no trace of this internal dynamics; it remains stationary in spite of the time-dependent interior.

  5. Effect of Conductor Verbalization, Dynamic Markings, Conductor Gesture, and Choir Dynamic Level on Singers' Dynamic Responses.

    Science.gov (United States)

    Skadsem, Julie A.

    1997-01-01

    Examines the effects of conductor verbalization, dynamic markings, conductor gesture, and choir dynamic level on individual singers' dynamic responses. Indicates that verbal instructions from the conductor elicited significantly stronger dynamic performance responses than did the other instructional conditions. Suggests that additional research…

  6. Voltage Controlled Dynamic Demand Response

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    . An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

  7. Analog circuit design designing dynamic circuit response

    CERN Document Server

    Feucht, Dennis

    2010-01-01

    This second volume, Designing Dynamic Circuit Response builds upon the first volume Designing Amplifier Circuits by extending coverage to include reactances and their time- and frequency-related behavioral consequences.

  8. Dynamic characteristics of peripheral jet ACV. III - Coupling motion of heaving and pitching

    Science.gov (United States)

    Mori, T.; Maeda, H.

    The paper presents the dynamic characteristics of peripheral jet ACV (Air Cushion Vehicle) which has two degrees of freedom, i.e., heaving and pitching motion. The experiments are carried out for an ACV model, noting that the experimental results agree considerably with the analytical values. Furthermore, the response characteristics of ACV induced by the ground board oscillations of various modes are also investigated.

  9. Dynamic Response of Embedded Structures.

    Science.gov (United States)

    1991-07-15

    1 (202) 767-6963 AFOSR/Nh 00 FORM 1473, 83 APR EDITION OF I JAN 73 IS OBSOLETE. Uwc A ____________ SECURITY CLASSIFICATION OF THIS PAGE...4. Baker W. E., Westine P. S., Dodge F. T., "Similarity Methods in Engineering Dynamics", Hayden Book Company, Inc., New Jerset, 1978. 5. Bazant , Z...P., "Size Effect in Blunt Fracture: Concrete, Rock, Metal", ASCE, Journal of Engineering Mechanics, Vol. 110, No. 4, April 1984. 6. Bazant , Z. P

  10. Nonlinear Dynamic Characteristics of Combustion Wave in SHS Process

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The characteristic of combustion wave and its change were analyzed by numerical value calculation and computer simulation,based on the combustion dynamical model of SHS process. It is shown that with the change of condition parameters in SHS process various time-space order combustion waves appear.It is concluded from non-liner dynamical mechanism analysis that the strong coupling of two non-linear dynamical processes is the dynamical mechanism causing the time-space order dissipation structures.

  11. 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.

  12. Spacecraft Dynamic Characteristics While Deploying Flexible Beams

    Institute of Scientific and Technical Information of China (English)

    程绪铎; 李俊峰; 樊勇; 王照林

    2002-01-01

    The attitude dynamic equations of a spacecraft while deploying two flexible beams and the beam equations were developed from momentum theory. The dynamic equations were solved numerically using the Runge-Kutta method to calculate the vibration amplitudes of the flexible beams and the attitude angular velocity. The results show that the vibration amplitudes increase as the beam length increases or as the initial attitude angular velocity increases. The results also show that the vibration amplitudes decrease as the deployment velocity increases.

  13. Dynamical characteristics of software trustworthiness and their evolutionary complexity

    Institute of Scientific and Technical Information of China (English)

    ZHENG ZhiMing; MA ShiLong; LI Wei; WEI Wei; JIANG Xin; ZHANG ZhanLi; GUO BingHui

    2009-01-01

    Developing trusted $oftwares has become an important trend and a natural choice In the development of software technology and applications, and software trustworthiness modeling has become a prerequisite and necessary means. To discuss and explain the basic scientific problems in software trustworthiness and to establish theoretical foundations for software trustworthiness measurement, combining the Ideas of dynamical system study, this paper studies evolutionary laws of software trustworthiness and the dynamical mechanism under the effect of various internal and external factors, and proposes dynamical models for software trustworthiness, thus, software trustworthiness can be considered as the statistical characteristics of behaviors of software systems in the dynamical and open environment. By analyzing two simple examples, the paper explains the relationship between the limit evolutionary behaviors of software trustworthiness attributes and dynamical system characteristics, and interprets the dynamical characteristics of software trustworthiness and their evolutionary complexity.

  14. Analysis of the dynamic hysteresis characteristic of finger seal

    Institute of Scientific and Technical Information of China (English)

    LEI Yanni; CHEN Guoding

    2007-01-01

    The research about hysteresis characteristic of finger seal (FS), which was carried out based on the model with static loads, could not reflect the dynamics behavior of FS system when the rotor runs at high speed. To solve this problem, the relations between the dynamics parameters, structure parameters as well as working parameters in the system were given out through the analysis of finite element analysis result. A mass-spring-damper dynamics model of FS system was proposed and the hysteresis characteristic of the FS system was analyzed. This work shows that the dynamics characteristic analysis of the FS is necessary and the dynamics model proposed in this paper is valid. This dynamics model is the basis for the optimization design of FS system.

  15. DIRECT NUMERICAL SIMUIATION OF BUBBLE-CLUSTER'S DYNAMIC CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A Direct Numerical Simulation (DNS) for understanding the dynamic response of bubble cluster to pulses of pressure perturbations has been studied by using a front-tracking method. The results show that owing to high nonlinearity, the bubble shape and volume oscillations caused by passing by pressure wave will be transformed into an in-phase volumetric oscillation of whole bubble cluster at a particular low-frequency. The value of the frequency is independent of the pulse excitations but the characteristics of the bubble cluster such as its bubble size, bulk void fraction and its spacial distribution etc. It is believed that this study provides important information for us to understand the coupling mechanism of cavitation cloud involved in cavitation resonance, a phenomenon noticed by one of the authors more than two decades ago.

  16. Numerical investigation of bubble nonlinear dynamics characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Jie, E-mail: shijie@hrbeu.edu.cn; Yang, Desen; Shi, Shengguo; Hu, Bo [Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001 (China); College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang, Haoyang; Jiang, Wei [College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001 (China)

    2015-10-28

    The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.

  17. Unascertained Factor Method of Dynamic Characteristic Analysis for Antenna Structures

    Institute of Scientific and Technical Information of China (English)

    ZHU Zeng-qing; LIANG Zhen-tao; CHEN Jian-jun

    2008-01-01

    The dynamic characteristic analysis model of antenna structures is built, in which the structural physical parameters and geometrical dimensions are all considered as unascertained variables, And a structure dynamic characteristic analysis method based on the unascertained factor method is given. The computational expression of structural characteristic is developed by the mathematics expression of unascertained factor and the principles of unascertained rational numbers arithmetic. An example is given, in which the possible values and confidence degrees of the unascertained structure characteristics are obtained. The calculated results show that the method is feasible and effective.

  18. One Type of Dynamic Scaling Characteristics for Synchronizability in LUHVGM

    Institute of Scientific and Technical Information of China (English)

    LIU; Qiang; FANG; Jin-qing; LI; Yong

    2012-01-01

    <正>The third level of unified hybrid network theoretical framework so-called large unifying hybrid variable growing model (LUHVGM) can be used to research basic characteristics of some social networks and high technology enterprise networks in theory as we investigated before. The research of dynamical synchronization is an important issue, which can rich and understand the characteristic of the LUHVGM. We found that the dynamical scaling relation and its exponent γ can be applied to describe the

  19. CALCULATION AND IMPROVEMENT OF DYNAMIC CHARACTERISTICS OF CENTRIFUGE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The modeling of the rotor-support system of a typical centrifuge is discussed. The impedance matching method, cooperating with Riccati transfer matrix method and modal analysis method are adopted to calculate its dynamic characteristics. The influences of the main parts to the critical speeds are analyzed. Based on the analysis, a critical speed in the operating speed range is tuned successfully, and thus the dynamic characteristics of the centrifuge are much improved.

  20. Dynamic characteristics of rocks and method of their determine

    Directory of Open Access Journals (Sweden)

    Radoslav Schügerl

    2009-01-01

    Full Text Available 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; and especially dynamic Poisson´s ratio νdyn. These parameters were obtained by laboratory testing of conglomerate samples.

  1. Dynamic characteristics of an NC table with phase space reconstruction

    Institute of Scientific and Technical Information of China (English)

    Linhong WANG; Bo WU; Runsheng DU; Shuzi YANG

    2009-01-01

    The dynamic properties of a numerical control (NC) table directly interfere with the accuracy and surface quality of work pieces machined by a computer numerical control (CNC) machine. Phase space reconstruction is an effective approach for researching dynamic behaviors of a system with measured time series. Based on the theory and method for phase space reconstruction, the correlation dimension, maximum Lyapunov exponent, and dynamic time series measured from the NC table were analyzed. The characteristic quantities such as the power spectrum, phase trajectories, correlation dimension, and maximum Lyapunov exponent are extracted from the measured time series. The chaotic characteristic of the dynamic properties of the NC table is revealed via various approaches.Therefore, an NC table is a nonlinear dynamic system. This research establishes a basis for dynamic system discrimi-nation of a CNC machine.

  2. Dynamical characteristics of ice supersaturated regions

    Directory of Open Access Journals (Sweden)

    K. Gierens

    2012-12-01

    Full Text Available The typical distributions of dynamical fields within ice supersaturated regions are investigated. The dynamical fields divergence, relative vorticity, and vertical velocity are analysed statistically in two ways, namely using the unconditioned data and data conditioned on the presence of ice supersaturation. Two geographical regions are considered, namely Europe (250 hPa level and the tropical belt from 30° S to 30° N on two pressure levels (200 and 150 hPa. The study is based on forecast data from the European Centre for Medium-Range Weather Forecasts for four months covering the four seasons, June, September, December 2011 and March 2012. We find that histograms (frequency distributions and low order moments of the dynamical fields differ substantially and statistically significantly inside and outside of ice supersaturated regions. As expected, upward and divergent flow favours ice supersaturation. But we find also that ice supersaturation is mostly located in anti-cyclonic flow. The latter result is probably due to the structure of warm/moist and cold/dry air streams in synoptic disturbances in mid-latitudes, but probably merely coincidental in the tropical belt.

  3. Dynamical characteristics of ice supersaturated regions

    Directory of Open Access Journals (Sweden)

    K. Gierens

    2012-08-01

    Full Text Available The typical distributions of dynamical fields within ice supersaturated regions are investigated. The dynamical fields divergence, relative vorticity, and vertical velocity are analysed statistically in two ways, namely using the unconditioned data and data conditioned on the presence of ice supersaturation. Two geographical regions are considered, namely Europe (250 hPa level and the tropical belt from 30° S to 30° N on two pressure levels (200 and 150 hPa. The study is based on forecast data from the European Centre for Medium-Range Weather Forecasts for March 2012 solely. We find that histograms (frequency distributions and low order moments of the dynamical fields differ substantially and statistically significantly inside and outside of ice supersaturated regions. As expected, upward and divergent flow favours ice supersaturation. But we find also that ice supersaturation is mostly located in anti-cyclonic flow. The latter result is probably due to the structure of warm/moist and cold/dry air streams in synoptic disturbances in mid-latitudes, but probably merely coincidental in the tropical belt.

  4. Dynamic Responsive Systems for Catalytic Function.

    Science.gov (United States)

    Vlatković, Matea; Collins, Beatrice S L; Feringa, Ben L

    2016-11-21

    Responsive systems have recently gained much interest in the scientific community in attempts to mimic dynamic functions in biological systems. One of the fascinating potential applications of responsive systems lies in catalysis. Inspired by nature, novel responsive catalytic systems have been built that show analogy with allosteric regulation of enzymes. The design of responsive catalytic systems allows control of catalytic activity and selectivity. In this Review, advances in the field over the last four decades are discussed and a comparison is made amongst the dynamic responsive systems based on the principles underlying their catalytic mechanisms. The catalyst systems are sorted according to the triggers used to achieve control of the catalytic activity and the distinct catalytic reactions illustrated. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. ANALYSIS OF THE DYNAMIC CHARACTERISTICS AND EARTHQUAKE RESPONSE IN ONE SUPER-HIGH STRUCTURE%超限高层结构动力特性及抗震性能分析

    Institute of Scientific and Technical Information of China (English)

    范伟霞; 赵群昌

    2011-01-01

    The research object in this text is the actual project-one reinforced concrete frame-corewall super-high structure of Changzhou city (42 layers above the ground 175meter high). Through the use of finite element software Etabs, it analyzed the building's structural dynamic characteristics to determine the mede decomposition reasonable mode of participation, as well as through flexible time-analysis methods, it analyzed the earthquake response of the structure in the most adverse effects of seismic wave. The steel structure that has been designed conforms to the requirement of the Chinese cedes. The method of Finite Element Analysis on super-high provides to compare.%常州市某超限高层建筑,结构高175m,地上42层,采用钢筋混凝土框架一核心筒结构,通过使用有限元软件Etabs,分析该建筑的结构动力特性,确定振型分解法的合理振型参与数,以及通过弹性时程法分析在最不利地震波作用下该结构的地震反应.结构符合国家现行规范要求,计算方法和结论对于运用有限元软件计算超限高层建筑有一定的参考价值.

  6. Modal Perturbation Method for the Dynamic Characteristics of Timoshenko Beams

    OpenAIRE

    2005-01-01

    Timoshenko beams have been widely used in structural and mechanical systems. Under dynamic loading, the analytical solution of a Timoshenko beam is often difficult to obtain due to the complexity involved in the equation of motion. In this paper, a modal perturbation method is introduced to approximately determine the dynamic characteristics of a Timoshenko beam. In this approach, the differential equation of motion describing the dynamic behavior of the Timoshenko beam can be transformed int...

  7. Dynamic characteristics and seismic stability of expanded polystyrene geofoam embankments

    Science.gov (United States)

    Amini, Zahra A.

    Expanded Polystyrene (EPS) geofoam has become a preferred material in various construction applications due to its light weight. Application of EPS accelerates the projects particularly on soft soils. The focus of this research is on the application of the EPS in embankments and its behavior mainly under harmonic vibration. The goal of this study was to investigate dynamic characteristics of freestanding vertical EPS geofoam embankment and address potential seismic issues that result from the distinguished dynamic behavior of such systems due to the layered and discrete block structure. A series of experimental studies on EPS 19 and a commercially available adhesive was conducted. Two-dimensional numerical analyses were performed to replicate the response of EPS geofoam embankment to horizontal and vertical harmonic motions. The results of the analyses have shown that for some acceleration amplitude levels interlayer sliding is expected to occur in EPS geofoam embankments almost immediately after the start of the base excitation; however, as a highly efficient energy dissipation mechanism sliding ceases rapidly. Shear keys and adhesive may be used to prevent interlayer sliding if they cover the proper extent of area of the embankment. EPS blocks placed in the corners of the embankment and at the edges of the segment prohibited from sliding may experience high stress concentrations. The embankment may show horizontal sway and rocking once sliding is prevented.

  8. Dynamic Response Testing in an Electrically Heated Reactor Test Facility

    Science.gov (United States)

    Bragg-Sitton, Shannon M.; Morton, T. J.

    2006-01-01

    Non-nuclear testing can be a valuable tool in development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and full nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics, and assess potential design improvements at a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE-100a heat pipe cooled, electrically heated reactor and heat exchanger hardware, utilizing a one-group solution to the point kinetics equations to simulate the expected neutronic response of the system (Bragg-Sitton, 2005). The current paper applies the same testing methodology to a direct drive gas cooled reactor system, demonstrating the applicability of the testing methodology to any reactor type and demonstrating the variation in system response characteristics in different reactor concepts. In each testing application, core power transients were controlled by a point kinetics model with reactivity feedback based on core average temperature; the neutron generation time and the temperature feedback coefficient are provided as model inputs. Although both system designs utilize a fast spectrum reactor, the method of cooling the reactor differs significantly, leading to a variable system response that can be demonstrated and assessed in a non-nuclear test facility.

  9. 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.

  10. Study on the Dynamic Characteristic of Lathe Headstock

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jian; WANG Taiyong; LI Haihong; LI Zhitan

    2006-01-01

    In order to provide reliable data for the dynamic design or modification of a tool machine, the dynamic characteristics of the headstock, which is the main component to bear moment, must be obtained precisely. In the paper, the method based on the combination of calculation mode and experiment mode is proposed to analyze the dynamic characteristics of the headstock. The modal parameters and the mode shapes are calculated by ANSYS7.1 software. According to the FEM calculating results, the experiment parameters can be selected correctly. The modal parameters of the headstock have to be calculated and identified precisely. On the basis of these modal parameters, the faults of the headstock are shown and its weak points of design are illustrated. A conclusion is drawn that some reasonable reinforce positions could greatly improve the dynamic characteristics of the system and this approach is proved to be precise and reliable.

  11. Nonlinear dynamic characteristic analysis of jointed beam with clearance

    Science.gov (United States)

    Zhang, Jing; Guo, Hong-Wei; Liu, Rong-Qiang; Wu, Juan; Kou, Zi-Ming; Deng, Zong-Quan

    2016-12-01

    The impact and elasticity of discontinuous beams with clearance frequently affect the dynamic response of structures used in space missions. This study investigates the dynamic response of jointed beams which are the periodic units of deployable structures. The vibration process of jointed beams includes free-play and impact stages. A method for the dynamic analysis of jointed beams with clearance is proposed based on mode superposition and instantaneous static deformation. Transfer matrix, which expresses the relationship of the responses before and after the impact of jointed beams, is derived to calculate the response of the jointed beams after a critical position. The dynamic responses of jointed beams are then simulated. The effects of various parameters on the displacement and velocity of beams are investigated.

  12. MECHANICAL CHARACTERISTICS OF DYNAMIC CLIMBING ROPES

    Directory of Open Access Journals (Sweden)

    Stojan Burnik

    2011-08-01

    Full Text Available Climbing rope is certainly one of the most important pieces of climbing equipment. On market there are many manufacturers of dynamic climbing ropes and even more of their products. All the ropes meet the requirements of the standards, which ensure that the ropes are safe enough for use in climbing. However the requirements are set only under certain conditions. In reality climbing ropes are exposed to various conditions that are many times different to those set by the standards. Consequently there are many different falls, which lead to very different loads of impact. By using appropriate method of testing rope samples made by three different manufacturers we discovered that there are differences between all three manufacturers. This leads us to a suggestion that standards should be improved.

  13. Dynamic epigenetic responses to muscle contraction

    DEFF Research Database (Denmark)

    Rasmussen, Morten; Zierath, Juleen R; Barrès, Romain

    2014-01-01

    Skeletal muscle is a malleable organ that responds to a single acute exercise bout by inducing the expression of genes involved in structural, metabolic and functional adaptations. Several epigenetic mechanisms including histone H4 deacetylation and loss of promoter methylation have been implicated...... in modifying exercise-responsive gene expression. These transient changes suggest that epigenetic mechanisms are not restricted to early stages of human development but are broad dynamic controllers of genomic plasticity in response to environmental factors....

  14. Dynamic Response Testing in an Electrically Heated Reactor Test Facility

    Science.gov (United States)

    Bragg-Sitton, Shannon M.; Morton, T. J.

    2006-01-01

    Non-nuclear testing can be a valuable tool in the development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and fueled nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics, and assess potential design improvements at a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE-100a heat pipe (HP) cooled, electrically heated reactor and heat exchanger hardware, utilizing a one-group solution to the point kinetics equations to simulate the expected neutronic response of the system. Reactivity feedback calculations were then based on a bulk reactivity feedback coefficient and measured average core temperature. This paper presents preliminary results from similar dynamic testing of a direct drive gas cooled reactor system (DDG), demonstrating the applicability of the testing methodology to any reactor type and demonstrating the variation in system response characteristics in different reactor concepts. Although the HP and DDG designs both utilize a fast spectrum reactor, the method of cooling the reactor differs significantly, leading to a variable system response that can be demonstrated and assessed in a non-nuclear test facility. Planned system upgrades to allow implementation of higher fidelity dynamic testing are also discussed. Proposed DDG

  15. Nonlinear dynamical characteristics of bed load motion

    Institute of Scientific and Technical Information of China (English)

    BAI; Yuchuan; XU; Haijue; XU; Dong

    2006-01-01

    Bed forms of various kinds that evolve naturally on the bottom of sandy coasts and rivers are a result of the kinematics of bed load transport. Based on the group motion of particles in the bed load within the bottom layer, a study on the nonlinear dynamics of bed load transport is presented in this paper. It is found that some development stages, such as the initiation, the equilibrium sediment transport, and the transition from a smooth bed to sand dunes, can be accounted for by different states in the nonlinear system of the bed load transport. It is verified by comparison with experimental data reported by Laboratoire Nationae D'Hydraulique, Chatou, France, that the evolution from a smooth bed to sand dunes is determined by mutation in the bed load transport. This paper presents results that may offer theoretical explanations to the experimental observations. It is also an attempt to apply the state-of-the-art nonlinear science to the classical sediment transport mechanics.

  16. MONITORING THE DYNAMIC CHARACTERISTICS OF TALL BUILDINGS BY GPS TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Dynamic characteristics of large structures,such as tall buildings,long-span suspension,cable-stayed bridges and tall chimneys,are key to assess their drift and stress conditions.The dynamic characteristics of large structures are difficult to measure directly under the condition of earthquakes or strong winds using traditional techniques such as laser collimator,total station and accelerometers.Therefore there is a great need for developing new method or technique for this purpose.Recent advances in Global Positioning System (GPS) technology provide a great opportunity to monitor long-period changes of structures reliably.GPS receivers capable to gauge the motion at the centimeter or sub-centimeter level with sampling frequency 10Hz or even 20 Hz are now available from several manufacturers.To the authors' knowledge,the capability of identifying dynamic characteristics from GPS observations has not been widely verified.For the feasibility study on using kinematic GPS technology to identify the dynamic characteristics of tall buildings,some experiments were conducted in a simulative environment.This paper discusses in detail the experiment device,and the ways through them GPS data are recorded,processed and analyzed.With post-processing version of NovAtel's Softsurv software and auto-regressive (AR) spectral analysis method,relative displacements and corresponding vibrating frequencies have been derived from GPS observations.The results indicate that the dynamic characteristics can be identified accurately by kinematic GPS technology.

  17. Characteristics, dynamics and significance of marine snow

    Science.gov (United States)

    Alldredge, Alice L.; Silver, Mary W.

    Macroscopic aggregates of detritus, living organisms and inorganic matter known as marine snow, have significance in the ocean both as unique, partially isolated microenvironments and as transport agents: much of surface-derived matter in the ocean fluxes to the ocean interior and the sea floor as marine snow. As microhabitats, marine snow aggregates contain enriched microbial communities and chemical gradients within which processes of photosynthesis, decomposition, and nutrient regeneration occur at highly elevated levels. Microbial communities associated with marine snow undergo complex successional changes on time scales of hours to days which significantly alter the chemical and biological properties of the particles. Marine snow can be produced either de novo by living plants and animals especially as mucus feeding webs of zooplankton, or by the biologically-enhanced physical aggregation of smaller particles. By the latter pathway, microaggregates, phytoplankton, fecal pellets, organic debris and clay-mineral particles collide by differential settlement or physical shear and adhere by the action of various, biologically-generated, organic compounds. Diatom flocculation is a poorly understood source of marine snow of potential global significance. Rates of snow production and breakdown are not known but are critical to predicting flux and to understanding biological community structure and transformations of matter and energy in the water column. The greatest challenge to the study of marine snow at present is the development of appropriate technology to measure abundances and characteristics of aggregates in situ.

  18. The contract murderer: patterns, characteristics, and dynamics.

    Science.gov (United States)

    Schlesinger, L B

    2001-09-01

    A case of an independent professional contract murderer, who killed over 100 people, is reported. After eluding law enforcement for 30 years, the subject killed several associates who he believed could implicate him in various crimes. These homicides eventually led to his arrest, since the victims were individuals who could be linked to him. This hit man had a background of poverty and childhood abuse but, as an adult, had pursued a middle-class lifestyle and kept his family totally separate from his criminal career. In addition, he had a number of characteristics that helped him carry out his crimes in a highly planned, methodical, and organized manner: he had adept social judgment; personality traits of orderliness, control, and paranoid vigilance; useful defense mechanisms of rationalization and reframing; and an exceptional ability to encapsulate emotions. This case is discussed within the context of contract murder, a crime that occurs relatively frequently and is probably increasing; yet it often goes undetected, the arrest rate is low, and the offender is rarely studied.

  19. Dynamic Response of Flexible Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Yu-qiao Zheng

    2013-07-01

    Full Text Available Aiming at the non-stationary and stall flutter problems of wind turbine blade caused by transient load fluctuations, the dynamic properties of wind turbine were studied, the blade was simplify to a cantilever beam in case of the action of shear deformation and cross section rotating effect were considered in this analysis, equations of the blade were established based on D'Alemberts' principle and the principle of virtual displacement. The dynamic response of the wind turbine was solved by using the finite element method under the transient load environment. A 29.2 m rotor blade, previously reported in specialized literature, was chosen as a case study to validate dynamic behaviour predicted by a Timoshenko beam model. It is concluded that despite its simplicity, The cross-sectional shear-deformation  has great influence on  dynamic response of the blade.Dynamic model is sufficiently accurate to serve as a design tool for the recursive analyses required during design and optimization stages of wind turbines using only readily available computational tools.

  20. Dynamic-tensile-extrusion response of fluoropolymers

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Eric N [Los Alamos National Laboratory; Trujillo, Carl P [Los Alamos National Laboratory; Gray, George T [Los Alamos National Laboratory

    2009-01-01

    The current work applies the recently developed Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) technique to polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE). Similar to the Taylor Impact Rod, Dynamic-Tensile-Extrusion is a strongly integrated test, probing a wide range of strain rates and stress states. However, the stress state is primarily tensile enabling investigation of dynamic tensile failure modes. Here we investigate the influence of this propensity to neck or not between PCTFE and PTFE on their response under dynamic tensile extrusion loading. The results of the Dyn-Ten-Ext technique are compared with two classic techniques. Both polymers have been investigated using Tensile Split Hopkinson Pressure Bar. The quasistatic and dynamic responses of both fluoro-polymers have been extensively characterized. The two polymers exhibit significantly different failure behavior under tensile loading at moderate strain rates. Polytetrafluoroethylene resists formation of a neck and exhibits significant strain hardening. Independent of temperature or strain rate, PTFE sustains true strains to failure of approximately 1.5. Polychlorotrifluoroethylene, on the other hand, consistently necks at true strains of approximately 0.05.

  1. Optimal Design of DC Electromagnets Based on Imposed Dynamic Characteristics

    Directory of Open Access Journals (Sweden)

    Sergiu Ivas

    2016-10-01

    Full Text Available In this paper is proposed a method for computing of optimal geometric dimensions of a DC electromagnet, based on the imposed dynamical characteristics. For obtaining the optimal design, it is built the criterion function in an analytic form that may be optimized in the order to find the constructive solution. Numerical simulations performed in Matlab software confirm the proposed work. The presented method can be extended to other electromagnetic devices which frequently operate in dynamic regime.

  2. Mathematical Modeling Social Responsibility for Dynamic Organizations

    Directory of Open Access Journals (Sweden)

    Farzaneh Chavoshbashi

    2012-03-01

    Full Text Available Dynamic organizations as accountable organizations, for transparency and accountability to its stakeholders to stakeholders for their toward performance there should express their commitment to social responsibility are through their values and ensure that this commitment throughout the organization are now and thus will have a social responsibility for their mutual benefit, so there is more and more coherent in their ethical approach takes advantage and the community and stakeholders and the organization will have better performance and strengths. Because of interest in social responsibility, in this paper dynamic model is presented for Corporate Social Responsibility of Bionic organization. Model presented a new model is inspired by chaos theory and natural systems theory based on bifurcation in creation to be all natural systems, realizing the value of responsibility as one of the fundamental values of social and institutional development that the relationship between business and work environment in the global market economy and range will be specified. First Social Responsibility factors identified, then experts and scholars determine the weight of the components and technical coefficient for modeling and paired comparison has been done using MATLAB mathematical Software.

  3. Numerical Calculation of Artillery-Fuze System Dynamic Characteristics

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-bin; LIU Ming-jie; TAN Hui-min

    2007-01-01

    A numerical calculation method based on the finite element analysis of dynamic characteristics of artillery-fuze system is discussed in detail. Pretension element is used to mesh the couple structure between artillery and fuze to analyze the change of dynamic characteristics of artillery-fuze system when pre-tightening force varies between artillery and fuze. Numerical calculation of the finite element analysis and actual hammering test of a artillery-fuze system are carried out with the same input to verify the accuracy of numerical calculation. The results show that the finite element model of artillery-fuze system is credibl e and the calculation accuracy is perfect.

  4. 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.

  5. Vibration Response Characteristics of the Cross Tunnel Structure

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2016-01-01

    Full Text Available It is well known that the tunnel structure will lose its function under the long-term repeated function of the vibration effect. A prime example is the Xi’an cross tunnel structure (CTS of Metro Line 2 and the Yongningmen tunnel, where the vibration response of the tunnel vehicle load and metro train load to the structure of shield tunnel was analyzed by applying the three-dimensional (3D dynamic finite element model. The effect of the train running was simulated by applying the time-history curves of vibration force of the track induced by wheel axles, using the fitted formulas for vehicle and train vibration load. The characteristics and the spreading rules of vibration response of metro tunnel structure were researched from the perspectives of acceleration, velocity, displacement, and stress. It was found that vehicle load only affects the metro tunnel within 14 m from the centre, and the influence decreases gradually from vault to spandrel, haunch, and springing. The high-speed driving effect of the train can be divided into the close period, the rising period, the stable period, the declining period, and the leaving period. The stress at haunch should be carefully considered. The research results presented for this case study provide theoretical support for the safety of vibration response of Metro Line 2 structure.

  6. Anomalous Dynamical Responses in a Driven System

    CERN Document Server

    Dutta, Suman

    2016-01-01

    The interplay between structure and dynamics in non-equilibrium steady-state is far from understood. We address this interplay by tracking Brownian Dynamics trajectories of particles in a binary colloid of opposite charges in an external electric field, undergoing cross-over from homogeneous to lane state, a prototype of heterogeneous structure formation in non-equilibrium systems. We show that the length scale of structural correlations controls heterogeneity in diffusion and consequent anomalous dynamic responses, like the exponential tail in probability distributions of particle displacements and stretched exponential structural relaxation. We generalise our observations using equations for steady state density which may aid to understand microscopic basis of heterogeneous diffusion in condensed matter systems.

  7. Dynamic lateral response of suction caissons

    DEFF Research Database (Denmark)

    Latini, Chiara; Zania, Varvara

    2017-01-01

    Deeper water installations of offshore wind turbines may be supported by jacket structures. This study investigates the dynamic response of suction caissons for jackets by analysing 3D finite element models in the frequency domain. The numerical modelling was firstly validated by analytical...... solutions for pile foundations. Groups of crucial dimensionless parameters related to the soil profile and the foundation geometry are identified and their effects on the response of suction caissons are studied. Static stiffness coefficients are presented in a form of mathematical formulas obtained...... by fitting the numerical results, pertaining foundations with different slenderness ratios and embedded in different soil profiles. Sensitivity of the dynamic impedances of suction caissons on the skirt length was showed in this study. Moreover, the results for the suction caissons indicated that the overall...

  8. Dynamic characteristics of controlled MR-STMDs of Wolgograd Bridge

    Science.gov (United States)

    Weber, F.

    2013-09-01

    This paper describes the dynamic characteristics of an adaptive tuned mass damper concept that is based on a real-time semi-actively controlled MR damper (MR-STMD) and is installed in the Wolgograd Bridge. The measurements and simulations of the prototype MR-STMD on the 15.6 m Empa bridge at different disturbing force levels demonstrate that the MR-STMD can cope with the nonlinear effect by which the resonance frequency and damping ratio of the Empa bridge depend on the amplitude and thereby on the excitation level. Whereas the efficiency of the MR-STMD is hardly affected by the aforementioned nonlinear effects, the passive TMD shows strong de-tuning. The tests for fast changes in frequency and amplitude of the disturbing force show that the response of the Empa bridge with the MR-STMD is smaller both during steady state and transient conditions than with a passive TMD, and the relative motion amplitudes in the MR-STMD are smaller or equal to those in the passive TMD. The force tracking accuracies of the prototype MR-STMD and of the Wolgograd MR-STMD are shown to be accurate, which generates precise frequency tuning of the MR-STMD in real-time and thereby explains the achievements described above. The test results indicate that the real-time controlled MR-STMD is an efficient and robust tool for the mitigation of structural vibrations.

  9. Dynamic Response of Three-Layered Annular Plate with Imperfections

    Directory of Open Access Journals (Sweden)

    Pawlus Dorota

    2015-02-01

    Full Text Available This paper presents the imperfection sensitivity of annular plate with three-layered structure. The plate composed of thin elastic facings and a thicker elastic core is loaded in facing plane. The classical issue of a three-layered plate was solved for dynamic deflection problem using the approximation methods: orthogonalization and finite difference. The solution includes the axisymmetric and asymmetric plate modes of the dynamic stability loss. The evaluation of the rate of plate sensitivity to imperfection of plate preliminary geometry has been enriched by the analysis of plate models built of finite elements. The ABAQUS program has been used. The numerous calculation results in the form of deflection characteristics, buckling modes, values of critical parameters create the view of response of dynamic plate structure with different rate of imperfection and linear in time loading growth, too.

  10. 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 tw...

  11. On Dynamic Characteristics of Culture and its Implications

    Institute of Scientific and Technical Information of China (English)

    赵凌志

    2015-01-01

    This paper mainly discusses the dynamic characteristic of western culture and Chinese culture from the intercultural perspective.Then it puts forward some implications for English teaching,it indicates that English teachers should pay due attention to improve the students cultural awareness and their own cultural teaching ability,adjust teaching content to adapt them to cultural changes.

  12. Hydraulic Self Servo Swing Cylinder Structure Optimization and Dynamic Characteristics Analysis Based on Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    Lin Jiang; Ruolin Wu∗and Zhichao Zhu

    2015-01-01

    The dynamic characteristics of hydraulic self servo swing cylinder were analyzed according to the hydraulic system natural frequency formula. Based on that, a method of the hydraulic self servo swing cylinder structure optimization based on genetic algorithm was proposed in this paper. By analyzing the four parameters that affect the dynamic characteristics, we had to optimize the structure to obtain as larger the Dm ( displacement) as possible under the condition with the purpose of improving the dynamic characteristics of hydraulic self servo swing cylinder. So three state equations were established in this paper. The paper analyzed the effect of the four parameters in hydraulic self servo swing cylinder natural frequency equation and used the genetic algorithm to obtain the optimal solution of structure parameters. The model was simulated by substituting the parameters and initial value to the simulink model. Simulation results show that: using self servo hydraulic swing cylinder natural frequency equation to study its dynamic response characteristics is very effective. Compared with no optimization, the overall system dynamic response speed is significantly improved.

  13. Damage Characteristic of Interpenetrating Phase Composites under Dynamic Loading

    Institute of Scientific and Technical Information of China (English)

    WANG Fuchi; ZHANG Xu; WANG Yangwei; WANG Lu; MA Zhuang; FAN Qunbo

    2014-01-01

    In order to investigate the damage characteristic of ceramic-metal interpenetrating phase composite (IPC) under dynamic loading, uniaxial dynamic compression was performed to characterize the failure of SiC/Al composite with 15%porosity using a modified Split Hopkinson Pressure Bar (SHPB). High speed photography was used to capture the failure procedure and set up the relationship between deformation and real stress. The deformation control technology was used to obtain collected samples in different deformations under dynamic loading. Micro CT technology was utilized to acquire real damage distribution of these specimens. Moreover, SEM was employed in comparing the damage characteristics in IPC. A summary of the available experimental results showed that IPC without lateral confinement formed double cones. The different features compared with ceramic materials without restraint was shown to be the result of the lateral restraint effect provided by metal phase to ceramics skeleton.

  14. Study of the response surface prediction model of the dynamic response characteristics of the high-speed solenoid valve%高速电磁阀动态响应特性响应面预测模型的研究

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 范立云; 马修真; 王昊; 白云; 宋恩哲

    2014-01-01

    For a more effective design and matching of the parameters of the high-speed solenoid valve,the numeri-cal simulation method and response surface methodology(RSM)along with the design of experiments(DOE)are applied. The finite element model of the high-speed solenoid valve for the diesel engine electronic unit pump has been developed in the Ansoft Maxwell environment. Its accuracy has been verified through laboratory experiments and the maximum error rate of the closed response time is 2% and the maximum error rate of the open response time is 8.7%. The experimental research scheme of dynamic response characteristics of the high-speed solenoid valve was designed by central composite design(CCD). With the least square regression analysis,the multiple quadratic re-sponse surface models of the closed response time and open response time of the high-speed solenoid valve were ob-tained. The values of R2 and Q2 of the two models are 0.986,0.867 and 0.999,0.981,respectively,and the maxi-mum error rate of the closed response time and open response time are 5.1% and 1.6%,respectively.Simulation ex-periment proves that the model can accurately forecast the dynamic response characteristics of the high-speed sole-noid valve. This study provides an effective tool for the design and matching of the parameters of the high-speed so-lenoid valve.%为了更有效地进行高速电磁阀参数的设计及匹配,经常采用数值模拟方法和结合实验设计的响应面方法。在Ansoft Maxwell 电磁仿真环境中建立了柴油机电控单体泵高速电磁阀的有限元模型,通过与试验数据对比,得出电磁阀关闭响应时间最大误差为2%,开启响应时间最大误差为8.7%,验证了该仿真模型的准确性。通过中心复合设计实验设计方法,制定了高速电磁阀动态响应特性实验研究方案。应用最小二乘法进行回归分析,分别得出了高速电磁阀关闭响应时间、开启响应时间的多元

  15. Dynamic Response Analysis of a Floating Mooring System

    Institute of Scientific and Technical Information of China (English)

    LE Conghuan; DING Hongyan; ZHANG Puyang

    2014-01-01

    An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For this new system, most of collision energy is absorbed through the displacement of floating platforms. In order to illustrate the validity of the system, a series of model tests were conducted at a scale of 1:40. The coupled motion characteristics of the floating mooring platforms were discussed under regular and irregular waves, and the influences of wave direction and other characteristics on dynamic response of the system were analyzed. The results show that the mooring system is safest at 0˚of wave incident angle, whereas the most dangerous mooring state occurs at 90˚ of wave incident angle. Motion responses increase with the increase of wave height, but are not linearly related to changes in wave height.

  16. Dynamic Characteristics of Inter-Satellite Links in LEO Networks

    Institute of Scientific and Technical Information of China (English)

    王亮; 张乃通; 温萍萍

    2003-01-01

    To establish an efficient inter-satellite link (ISL) in an LEO network, the effect of geometric characteristics of ISL on the ISLs and the devices on the LEO satellite should be examined. Because of the continuous movement of the LEO satellite, the time-varying behaviours of the ISL's geometric charactersistics continuously change with the changes of the satellite's position on the orbit. These dynamic geometric characteristics of the ISLs are important for ISL's performance analyzing and the design of the devices on the LEO satellite. This paper describes dynamic geometric characteristics of ISL, analyzes the impact of these regulations on the tracking system of the satellite's antenna and the power adjusting system of the satellite's transmitter, with the Iridium system as an example.

  17. Characteristics of Multipath Effects in GPS Dynamic Deformation Monitoring

    Institute of Scientific and Technical Information of China (English)

    HUANG Shengxiang; JIN Xiangsheng; YANG Baocen

    2006-01-01

    The multipath has long been considered a major error source in GPS applications. The characteristics of the GPS signal multipath effects are analyzed, based on which an experiment that considers the characteristics of dynamic deformation monitoring has been carried out. The solution results of observation data in two successive days are processed by a method, which combines the wavelet filtering and the differential correction between two successive days. The research demonstrates that the multipath errors have stronger repeatability on successive days; after significantly mitigating the influence of multipath effects, the accuracy of three-dimensional positioning for GPS dynamic deformation monitoring can attain the mm level, an obvious accuracy improving particularly in vertical component. The characteristics of GPS signal multipath, the experimental scheme and the qualitative and quantitative analysis of results are detailed.

  18. Comparison of Dynamic Characteristics of Two Instrumented Tall Buildings

    DEFF Research Database (Denmark)

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

    2003-01-01

    Comparison of recorded structural earthquake response and predicted response by dynamic analysis provides vital information to structural designers on the effectiveness of current methods of dynamic analysis. There have been a number of previous studies of this nature, but only a few have paid...... 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...... of each other and have been subjected to ground motions from several earthquakes, among which the most significant are those from the 1994 Northridge earthquake. The results of this study showed that although the buildings were subjected to similar level of ground shaking their different structural...

  19. Structural optimization for nonlinear dynamic response

    DEFF Research Database (Denmark)

    Dou, Suguang; Strachan, B. Scott; Shaw, Steven W.

    2015-01-01

    condition, thereby providing a means for tailoring its nonlinear response. The method is applied to the fundamental nonlinear resonance of a clamped–clamped beam and to the coupled mode response of a frame structure, and the results show that one can modify essential normal form coefficients by an order...... resonant behaviour is being used for a variety of applications in sensing and signal conditioning. In this work, we describe a computational method that provides a systematic means for manipulating and optimizing features of nonlinear resonant responses of mechanical structures that are described...... by a single vibrating mode, or by a pair of internally resonant modes. The approach combines techniques from nonlinear dynamics, computational mechanics and optimization, and it allows one to relate the geometric and material properties of structural elements to terms in the normal form for a given resonance...

  20. State-space analysis of the dynamic characteristics of a variable thrust liquid propellant rocket engine

    Science.gov (United States)

    Zhang, Yu-Lin

    This paper states the application of state-space method to the analysis of the dynamic characteristics of a variable thrust liquid propellant rocket engine and presents a set of state equations for describing the dynamic process of the engine. An efficient numerical method for solving these system equations is developed. The theoretical solutions agree well with the experimental data. The analysis leads to the following conclusion: the set coefficient of the pulse width, the working frequency of the solenoid valves and the deviation of the critical working points of these valves are important parameters for determining the dynamic response time and the control precision of this engine. The methods developed in this paper may be used effectively in the analysis of dynamic characteristics of variable thrust liquid propellant rocket engines.

  1. Dynamic Response Characteristics of Asphalt Pavement Under Multi-axle Moving Load%多轴移动荷载下沥青路面的动态响应特性

    Institute of Scientific and Technical Information of China (English)

    裴建中; 吴浩; 陈勇; 王秉纲

    2011-01-01

    In order to analyze dynamic response characteristics of asphalt pavement under muhi axle moving load,a three-dimensional finite element model of asphalt pavement was established by field investigation. The influences of axle load with uniform distribution of single rear axle, dual rear axles and three rear axles and the axle load with non-uniform distribution of three rear axles and the three rear axles vehicles with impending front axle on pavement were studied respectively. Results show that the effect of each axle on pavement is independent when the wheelbase of multi axle vehicle is bigger than 3 m. Increase of number of axle makes the vertical displacement of pavement superpose and makes the maximal shear stress and compressive stress of pavement change inconspicuously. The influence of the middle axle of three rear axles vehicle on the vertical displacement of pavement is the greatest which increases by 23. 7% and 18. 2% compared with those of the front axle and rear axle respectively. Besides, the middle axle and rear axle has certain influence on the shear stress of pavement, but each axle has ahnost no influence on the maximal compressive stress of pavement. The research results indicate that the non uniform distribution of axle load of multi axle vehicle has significant influence on pavement faliure.%为分析多轴移动荷载下沥青路面的动态响应特性,通过现场调查建立了不同轴型作用下沥青路面的三维有限元模型,分别研究了单后轴、双后轴及三后轴轴载均匀分布、三后轴车轴载不均匀分布及三后轴车前轴悬空条件下对路面的影响。结果表明:多轴车轴距大于3m时,各轴对路面的作用相互独立,轴数的增加对路面竖向位移产生叠加作用,对路表最大剪应力及压应力影响不明显;三后轴车中轴对路面竖向位移作用最大,较前轴及后轴分别增大23.7%和18.2%,中轴及后轴对路表剪应力有一定影响,

  2. Dynamics response characteristics of second row female dummies in a 100% frontal crash test%100%正面碰撞中第二排女性假人的动力学响应特点

    Institute of Scientific and Technical Information of China (English)

    朱海涛; 白鹏; 张向磊

    2012-01-01

    The second seat row has a high riding rate but a low rider protection level in vehicles running in China. This paper investigates test methods based on the 100% frontal impact test rule of 2009 version of China New Car Assessment Program (C-NCAP), and presents a quantitative evaluation method for the biomechanics limit value of the second row passengers. Tests in vehicle 100% frontal impacts for 29 types of vehicles recently coming into China's market showed that the second row occupants suffered fatal neck injury in 17 types of the vehicles (58.8% of total vehicle samples) and fatal chest injury in 10 types of vehicles (34.5% of total vehicle samples). The analyses show that the seat belt shoulder strap, neck tension force, and chest compression displacement have an approximately linear relationship in the dynamics response characteristics of mixed III type, the 5th percentile, female dummies in the second row seats. The results indicate that the occupant upper body injury is mainly caused by the safety belt shoulder strap. Therefore, parameter optimization and adjustment are necessary for common safety belts to effectively reduce the harm.%中国乘用汽车第二排乘坐率高,对乘客员的保护力度不够。该文参考09版中国新车评价规程(C—NCAP)中的相关规则,研究了评价第二排乘员伤害的i00%正面碰撞的试验方法和基于生物力学限值指标的定量评分方法。对新近上市29款车型进行试验。结果表明:第二排乘员颈部遭受致命伤害的17款,占59%;胸部遭受致命伤害的10款,占35%。对第二排座椅上混合Ⅲ型第5%百分位的女性假人动力学响应的分析结果表明:安全带肩带力与颈部拉伸力、胸部压缩量之间呈近似线性关系。安全带肩带是造成假人上躯干伤害的主要原因。因此,为有效降低这种伤害,应优化、调整普通安全带参数。

  3. Numerical and Experimental Dynamic Characteristics of Thin-Film Membranes

    Science.gov (United States)

    Young, Leyland G.; Ramanathan, Suresh; Hu, Jia-Zhu; Pai, P. Frank

    2004-01-01

    Presented is a total-Lagrangian displacement-based non-linear finite-element model of thin-film membranes for static and dynamic large-displacement analyses. The membrane theory fully accounts for geometric non-linearities. Fully non-linear static analysis followed by linear modal analysis is performed for an inflated circular cylindrical Kapton membrane tube under different pressures, and for a rectangular membrane under different tension loads at four comers. Finite element results show that shell modes dominate the dynamics of the inflated tube when the inflation pressure is low, and that vibration modes localized along four edges dominate the dynamics of the rectangular membrane. Numerical dynamic characteristics of the two membrane structures were experimentally verified using a Polytec PI PSV-200 scanning laser vibrometer and an EAGLE-500 8-camera motion analysis system.

  4. General regularity of dynamic responses of slopes under dynamic input

    Institute of Scientific and Technical Information of China (English)

    QI Shengwen; WU Faquan; SUN Jinzhong

    2003-01-01

    Through lots of numerical simulations with FLAC3D, dynamic responses of slopes are comprehensively studied in this paper and the general regularities of the isoline of the coefficient of the displacement, velocity and acceleration of the slope section are reached. Given a certain material slope, if the height of the slope is less than a certain value, the displacement, velocity and acceleration linearly enlarge with elevation in the vertical direction; if the height of the slope surpasses the certain value, the displacement,velocity and acceleration do not linearly enlarge with elevation any more, on the other hand, they fluctuate with a certain rhythm. At the same time, the rhythm appears in the horizontal direction, and the displacement, velocity and acceleration of the slope surface enlarge near the slope surface. The distribution form of the isoline of the coefficient of displacement, velocity and acceleration in the section of the slope is remarkably affected by the slope angle. In the certain area near the slope surface, the isoline of displacement,velocity and acceleration is parallel to the surface of the slope; in the mean time the strike direction of the extremum area is parallel to the surface of the slope, too. The charts of the slope dynamic responses can be depicted with two indexes, one is the strike direction of the isoline, and the other is the number of the rhythm extremum area of the direction parallel to the surface of the slope.

  5. 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.

  6. Stability of dynamic response of suspension bridges

    Science.gov (United States)

    Capsoni, Antonio; Ardito, Raffaele; Guerrieri, Andrea

    2017-04-01

    The potential occurrence of internal parametric resonance phenomena has been recently indicated as a potential contributory cause of the appearance of critical dynamic states in long-span suspension bridges. At the same time, suspension bridges, in view of their flexibility, are prone to aeroelastic response, such as vortex shedding, torsional divergence and flutter. In this paper, a non-linear dynamic model of a suspension bridge is devised, with the purpose of providing a first attempt toward a unified framework for the study of aeroelastic and internal resonance instabilities. Inspired by the pioneering work of Herrmann and Hauger, the analyses have been based on a linearized formulation that is able to represent the main structural non-linear effects and the coupling given by aerodynamic forces. The results confirm that the interaction between aeroelastic effects and non-linear internal resonance leads to unstable conditions for wind speeds which can be lower than the critical threshold for standard aeroelastic predictions.

  7. Dynamic energy absorption characteristics of hollow microlattice structures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, YL; Schaedler, TA; Chen, X

    2014-10-01

    Hollow microlattice structures are promising candidates for advanced energy absorption and their characteristics under dynamic crushing are explored. The energy absorption can be significantly enhanced by inertial stabilization, shock wave effect and strain rate hardening effect. In this paper we combine theoretical analysis and comprehensive finite element method simulation to decouple the three effects, and then obtain a simple model to predict the overall dynamic effects of hollow microlattice structures. Inertial stabilization originates from the suppression of sudden crushing of the microlattice and its contribution scales with the crushing speed, v. Shock wave effect comes from the discontinuity across the plastic shock wave front during dynamic loading and its contribution scales with e. The strain rate effect increases the effective yield strength upon dynamic deformation and increases the energy absorption density. A mechanism map is established that illustrates the dominance of these three dynamic effects at a range of crushing speeds. Compared with quasi-static loading, the energy absorption capacity a dynamic loading of 250 m/s can be enhanced by an order of magnitude. The study may shed useful insight on designing and optimizing the energy absorption performance of hollow microlattice structures under various dynamic loads. (C) 2014 Elsevier Ltd. All rights reserved.

  8. IDENTIFICATION OF DYNAMIC CHARACTERISTICS OF AIRCRAFT GAS TEMPERATURE SENSORS

    Directory of Open Access Journals (Sweden)

    A. F. Sabitov

    2016-01-01

    Full Text Available The estimation of dynamic behavior of aircraft gas temperature sensors (GTS has to be done only in certified air installations and be based on recorded experimental transient response in accordance with the departmental standard. Experimental transient response has hindrances of different nature and can influence the accuracy of identification of dynamic behaviour of GTS. We suggested a new method to increase the accuracy of identification of dynamic behavior of GTS. The method is based on the use of amplitude spectrum of signal composed of experimental transient response. Shaped signal is an impulse decaying signal satisfying a Dirichlet condition and Fourier transform can apply to it to get amplitude spectrum. We worked out the relation between amplitude spectrum of shaped signals and time constant of dynamic behaviour for three mathematical models of GTS. The research showed that the information about dynamic behaviour of standard aircraft GTS is located in LF part of amplitude spectrum in the range of 0 to 1 rad/s and to 3 rad/s. The study revealed that hindrance in the transient response at frequency higher than 3 rad/s did not influence the accuracy of results if to use LF part of amplitude spectrum for the identification of dynamic behaviour of GTS. The amplitude spectrum of shaped signal can be estimated by measuring equipment like LF spectrum analyzer or calculated by software package with the function of fast Fourier transform. The value of time constant of certain mathematical model of GTS can be realized with the help of regression analysis or the use of embedded resources of different data processing systems. Thus, the method gives an opportunity to increase the accuracy of identification of dynamic behavior of GTS. 

  9. Analysis of the Dynamic Characteristics of Elliptical Gears

    Science.gov (United States)

    Liu, Xing; Nagamura, Kazuteru; Ikejo, Kiyotaka

    To date, elliptical gear has been commonly used in automobile, automatic machinery, pumps, flow meters and printing presses for its particular non-uniform rotation. However, the dynamic characteristics of elliptical gears have not been clarified yet. In this study, The calculation as well as the experiment of two elliptical gears, which are a single elliptical gear and a double elliptical gear, is carried out to analyze the dynamic characteristics of elliptical gears. General factors including the torque, the rotation speed and the tooth root stress of the test gears are investigated. According to the analysis conducted in this study, the dynamic input torque variation of elliptical gear becomes larger along with the increase of operating gear rotation speed and the experimental one increases much faster than the calculated one over the Critical Rotation Speed of Tooth Separation (CRSTS) of elliptical gear. The experimental input rotation speed varies according to the variation of input torque, leading to the difference between the experimental output rotation speed and the desired one. The calculation results of the CRSTS of elliptical gears are almost equal to the experimental ones. The dynamic load variation ratios of elliptical gear at different angular position as well as their changing trends with operating gear rotation speed are quite different from each other. And the experimental dynamic load variation ratios of elliptical gear show difference from the calculated ones because of tooth separation and tooth impact. The agreement of the calculation and experimental results proves the validity of this study.

  10. Vibration characteristic analysis and dynamic response study of gearbox casing%齿轮箱体振动特性的分析及动态响应研究

    Institute of Scientific and Technical Information of China (English)

    葛丹丹; 梅小龙; 樊文欣; 余锋祥

    2011-01-01

    After a 3D solid model of the gearbox is built, the modal analysis is carried out, and the natural frequencies and vibration modes of preceding ten orders are obtained. On this basis, modal superposition method is used to analyze the transient response of the gearbox casing in excitation conditions, and the dynamic response of the gearbox system is obtained. The results show that the maximum stress concentrates on the ribs of the lower gearbox casing under this loading, while the stress is very small on other parts of the gearbox casing. The dynamic response parameters obtained from calculation establishes foundation for the further structural optimization of the gearbox system.%在建立齿轮箱三维实体模型的基础上,对其进行模态分析,得出前10阶固有频率及振型。并利用模态叠加法对齿轮箱体工况激励下的瞬态响应进行分析,得出了齿轮箱系统的动态响应。结果表明,在这种载荷的作用下,最大应力集中出现在齿轮箱下箱体肋板区域,而箱体其他部位的应力值很小。通过计算得到的动态响应参数,为齿轮箱系统设计进一步优化奠定了基础。

  11. Dynamic stress intensity factor KⅢ and dynamic crack propagation characteristics of anisotropic materials

    Institute of Scientific and Technical Information of China (English)

    GAO Xin; WANG Han-gong; KANG Xing-wu

    2008-01-01

    Based on the mechanics of anisotropic materials,the dynamic propagation problem of a mode Ⅲ crack in an infinite anisotropic body is investigated.Stress,strain and displacement around the crack tip are expressed as an analytical complex function,which can be represented in power series.Constant coefficients of series are determined by boundary conditions.Expressions of dynamic stress intensity factors for a mode Ⅲ crack are obtained.Components of dynamic stress,dynamic strain and dynamic displacement around the crack tip are derived.Crack propagation characteristics are represented by the mechanical properties of the anisotropic materials,i.e.,crack propagation velocity M and the parameter α.The faster the crack velocity is,the greater the maximums of stress components and dynamic displacement components around the crack tip are.In particular,the parameter α affects stress and dynamic displacement around the crack tip.

  12. Structural optimization for nonlinear dynamic response.

    Science.gov (United States)

    Dou, Suguang; Strachan, B Scott; Shaw, Steven W; Jensen, Jakob S

    2015-09-28

    Much is known about the nonlinear resonant response of mechanical systems, but methods for the systematic design of structures that optimize aspects of these responses have received little attention. Progress in this area is particularly important in the area of micro-systems, where nonlinear resonant behaviour is being used for a variety of applications in sensing and signal conditioning. In this work, we describe a computational method that provides a systematic means for manipulating and optimizing features of nonlinear resonant responses of mechanical structures that are described by a single vibrating mode, or by a pair of internally resonant modes. The approach combines techniques from nonlinear dynamics, computational mechanics and optimization, and it allows one to relate the geometric and material properties of structural elements to terms in the normal form for a given resonance condition, thereby providing a means for tailoring its nonlinear response. The method is applied to the fundamental nonlinear resonance of a clamped-clamped beam and to the coupled mode response of a frame structure, and the results show that one can modify essential normal form coefficients by an order of magnitude by relatively simple changes in the shape of these elements. We expect the proposed approach, and its extensions, to be useful for the design of systems used for fundamental studies of nonlinear behaviour as well as for the development of commercial devices that exploit nonlinear behaviour.

  13. Dynamical response near quantum critical points

    CERN Document Server

    Lucas, Andrew; Podolsky, Daniel; Witczak-Krempa, William

    2016-01-01

    We study high frequency response functions, notably the optical conductivity, in the vicinity of quantum critical points (QCPs) by allowing for both detuning from the critical coupling and finite temperature. We consider general dimensions and dynamical exponents. This leads to a unified understanding of sum rules. In systems with emergent Lorentz invariance, powerful methods from conformal field theory allow us to fix the high frequency response in terms of universal coefficients. We test our predictions analytically in the large-N O(N) model and using the gauge-gravity duality, and numerically via Quantum Monte Carlo simulations on a lattice model hosting the interacting superfluid-insulator QCP. In superfluid phases, interacting Goldstone bosons qualitatively change the high frequency optical conductivity, and the corresponding sum rule.

  14. Dynamical Response near Quantum Critical Points

    Science.gov (United States)

    Lucas, Andrew; Gazit, Snir; Podolsky, Daniel; Witczak-Krempa, William

    2017-02-01

    We study high-frequency response functions, notably the optical conductivity, in the vicinity of quantum critical points (QCPs) by allowing for both detuning from the critical coupling and finite temperature. We consider general dimensions and dynamical exponents. This leads to a unified understanding of sum rules. In systems with emergent Lorentz invariance, powerful methods from quantum field theory allow us to fix the high-frequency response in terms of universal coefficients. We test our predictions analytically in the large-N O (N ) model and using the gauge-gravity duality and numerically via quantum Monte Carlo simulations on a lattice model hosting the interacting superfluid-insulator QCP. In superfluid phases, interacting Goldstone bosons qualitatively change the high-frequency optical conductivity and the corresponding sum rule.

  15. Dynamic Characteristics of Prosthetic Feet: A Comparison Between Modal Parameters of Walking, Running and Sprinting Foot

    Science.gov (United States)

    Noroozi, S.; Rahman, A. G. A.; Dupac, M.; Vinney, J. E.

    Current methods of evaluating the performance of Energy Storing and Returning (ESR) prosthesis are subjective and rely on VO2 consumption. Current prosthetic feet are designed for specific applications and the majority are designed for walking and moderate running. These mechanical feet have fixed mechanical and dynamic characteristics. They have to be selected to meet the requirement of the task and any use outside the domain of the task can result in extreme/severe lack of gait symmetry and loss of energy. Poor gait symmetry results is excess consumption of energy, back pain or fatigue. To investigate if a multipurpose foot can be designed to passively adapt to the walking or running condition one must first understand the different dynamics that are involved and are required from the task specific foot. Static tests have shown these feet to have non-linear stiffness, making the prediction of their dynamic response difficult. The most reliable method to test for dynamic characteristics is drop and modal testing. A method approach has been developed as part of this research to test and compare the dynamic characteristics of three different types of foot (natural frequency, mode shapes and damping). This is needed to explore the differences in the responses of these feet that allow one to be used for walking, one to be used for running and one to be used for sprinting with ease.

  16. STUDY ON DYNAMICS CHARACTERISTICS OF AN ELASTODYNAMIC SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The system dynamics model has been done. The contracting process of the curved-surface of the rubber disc is analyzed carefully, which is the main research aspect of the elastodynamics in the system. The coupling equation of the "elastic surface and fluid" is resolved by inverse resolution method. The main characteristics of the system, for instance, the departing-tube velocity, with which a carrier is to depart a launch tube, are estimated through resolving the simulation model of the system dynamics. The simulation is based on some known parameters and the experiment outcome of the elasticity modulus of a special rubber. On the other hand, the influences on the system characteristics accompanying with the changing of some system parameters are discussed. Finally, the conclusions are given that the elastodynamic system has a superior performance and that the system deserves to be developed further as a kind of launch device.

  17. Unified power flow controller: modeling and dynamic characteristic

    Science.gov (United States)

    Bach, D. H.; Loc, H. D.

    2005-12-01

    Unified power flow controller (UPFC) consists two converters. There are three purposes of this paper, firstly to illustrate the UPFC device based VSC designs, then to describe a decoupling method the UPFC's controller into two separate control systems of the shunt and the series converters respectively in realizing an appropriate coordination between them. Finally, using the Matlab tool to build a discrete simulator for the UPFC with 12 pulse converters. The simulation results show that the developed UPFC model is reflected the static and dynamic characteristics of the UPFC. The harmonics of the output of the model were analyzed. Using the simple power system with UPFC as an example, the dynamics characteristics were studied. The fault status of the system with UPFC was analyzed too.

  18. Study on Dynamic Characteristics of Ammonia Refrigerator System

    Science.gov (United States)

    Nakashima, Minoru; Ikegami, Yasuyuki; Hirao, Yasuhiro; Sudoh, Gaku; Shingoh, Masashi; Uehara, Haruo

    The dynamic characteristics of ammonia refrigerator system are observed when the expansion valve's opening is slightly changed. The refrigerator system is constructed with the reciprocal compressor, the plate type heat exchanger for the condenser and the evaporator, and the expansion valve. A simple simulation model for this refrigerator system is proposed to develop the computer-simulator of this ammonia refrigerator system and those simulation results are compared to above experimental results. For the development of the computer-simulator, simple but useful models, which can represent the dynamic characteristics of the refrigerator, are adopted for each components of the refrigerator system. The simulation shows the overall good agreement with experiment, without the time constant in the variation of the temperature at the evaporator outlet.

  19. Dynamic Response and Dynamic Failure Mode of a Weak Intercalated Rock Slope Using a Shaking Table

    Science.gov (United States)

    Fan, Gang; Zhang, Jianjing; Wu, Jinbiao; Yan, Kongming

    2016-08-01

    A large-scale shaking table test was performed to study the dynamic response of slopes parallel to geological bedding (bedding slopes) and slopes that cross-cut geological bedding (counter-bedding slopes). The test results show that the acceleration amplification coefficients increase with increasing elevation and, when the input earthquake amplitude is greater than 0.3 g, both bedding and counter-bedding slopes begin to show nonlinear dynamic response characteristics. With increasing elevation, the displacement of the bedding slope surface increases greatly. Conversely, the displacement of the counter-bedding slope surface increases first and then decreases; the slope develops a bulge at the relative elevation of 0.85. The displacement of the bedding slope surface is greater than that of the counter-bedding slope. The counter-bedding slope is more seismically stable compared with the bedding slope. Based on the Hilbert-Huang transform and marginal spectrum theories, the processes that develop dynamic damage of the bedding and counter-bedding slopes are identified. It is shown that the dynamic failure mode of the bedding slope is mainly represented by vertical tensile cracks at the rear of the slope, bedding slide of the strata along the weak intercalation, and rock collapse from the slope crest. However, the dynamic failure mode of the counter-bedding slope is mainly represented by staggered horizontal and vertical fissures, extrusion of the weak intercalation, and breakage at the slope crest.

  20. Dynamics of active cellular response under stress

    Science.gov (United States)

    de, Rumi; Zemel, Assaf; Safran, Samuel

    2008-03-01

    Forces exerted by and on adherent cells are important for many physiological processes such as wound healing and tissue formation. In addition, recent experiments have shown that stem cell differentiation is controlled, at least in part, by the elasticity of the surrounding matrix. Using a simple theoretical model that includes the forces due to both the mechanosensitive nature of cells and the elastic response of the matrix, we predict the dynamics of orientation of cells. The model predicts many features observed in measurements of cellular forces and orientation including the increase with time of the forces generated by cells in the absence of applied stress and the consequent decrease of the force in the presence of quasi-static stresses. We also explain the puzzling observation of parallel alignment of cells for static and quasi-static stresses and of nearly perpendicular alignment for dynamically varying stresses. In addition, we predict the response of the cellular orientation to a sinusoidally varying applied stress as a function of frequency. The dependence of the cell orientation angle on the Poisson ratio of the surrounding material can be used to distinguish systems in which cell activity is controlled by stress from those where cell activity is controlled by strain. Reference: Nature Physics, vol. 3, pp 655 (2007).

  1. Dynamic Responses of Mobile Offshore Base Connectors

    Institute of Scientific and Technical Information of China (English)

    余澜; 李润培; 舒志

    2003-01-01

    A Mobile Offshore Base (MOB) is a multi-purpose logistics base, which can be stationed in coastal or international waters. In the conceptual design of the MOB, attention should be paid to the dynamic responses of the inter-module connectors because tremendous loads occur in the connectors. In this paper, a study on dynamic responses of the MOB connectors is carried out by use of the Rigid Module Flexible Connector (RMFC) model which assumes that the module stiffness is significantly larger than that of the connector. In the analysis, the connector is modeled as a linear spring, which restricts relative translations but allows for relative rotations of modules. The 3-D source distribution method is adopted to determine the hydrodynamic forces of the modules, and the hydrodynamic interaction between modules is taken into account. The module motions and connector loads for 12 connector stiffness cases in regular and irregular waves are calculated with the multi-rigid-body motion equations. And the calculated results are compared with those from relative references. It is shown that the results obtained by different methods are in good agreement.

  2. Kinematic and Dynamic Characteristics Analysis of Bennett’ s Linkage

    Institute of Scientific and Technical Information of China (English)

    Jianfeng Li

    2015-01-01

    Bennett’ s linkage is a spatial fourlink linkage, and has an extensive application prospect in the deployable linkages.Its kinematic and dynamic characteristics analysis has a great significance in its synthesis and application. According to the geometrical conditions of Bennett ’ s linkage, the motion equations are established,and the expressions of angular displacement, angular velocity and angular acceleration of the followers and the displacement, velocity and acceleration of mass center of link are shown. Based on Lagrange’ s equation, the multi⁃rigid⁃body dynamic model of Bennett’ s linkage is established. In order to solve the reaction forces and moments of joint, screw theory and reciprocal screw method are combined to establish the computing method.The number of equations and unknown reaction forces and moments of joint are equal through adding link deformation equations. The influence of the included angle of adjacent axes on Bennett ’ s linkage ’ s kinematic characteristics, the dynamic characteristics and the reaction forces and moments of joint are analyzed. Results show that the included angle of adjacent axes has a great effect on velocity, acceleration, the reaction forces and moments of Bennett’ s linkage. The change of reaction forces and moments of joint are apparent near the singularity configuration.

  3. Dynamic Characteristics of PEM-FC/Woody Biomass Engine Hybrid Micro Grid

    Science.gov (United States)

    Obara, Shin'ya; Kito, Shunsuke; Hoshi, Akira; Sasaki, Seizi

    The combustion exhaust heat of woody biomass engine using Stirling cycle is high temperature. This exhaust heat is used for the city gas reforming reaction of a proton exchange membrane fuel cell (PEM-FC) system. The woody biomass engine generator has the characteristic that the greenhouse gas amount of emission with power generation is greatly reducible. In this paper, the micro grid system that introduces PEM-FC/woody biomass engine hybrid cogeneration (PWHC) is proposed. It depends on the dynamic characteristics of the grid for the power quality at the time of load fluctuation being added to the micro grid. Especially, the dynamic characteristics of the independent micro grid are important on security of power quality. So, in this paper, the response characteristic of PEM-FC and woody biomass engine was investigated by the experiment and the numerical analysis. Furthermore, the response characteristic of the PWHC independent micro grid including auxiliary machinery was investigated by the numerical simulation. Moreover, an improvement of dynamic characteristics is proposed using the method of adding proportional-plus-integral control to PWHC. If woody biomass engine is introduced into a house, 10.2s will be required to stabilize power quality at the maximum. On the other hand, when woody biomass engine corresponds to a base load and PEM-FC corresponds to the load exceeding the base load, settling time is less than 1.6 s. In this study, relation between the system configuration of the PWHC micro grid and the dynamic characteristics of the power was clarified.

  4. Nonlinear dynamic characteristics of SMA intravascular stent under radial stochastic loads.

    Science.gov (United States)

    Zhu, Zhiwen; Zhang, Qingxin; Xu, Jia

    2014-01-01

    Nonlinear dynamic characteristics of shape memory alloy (SMA) intravascular stent under radial stochastic loads were studied in this paper. Von de Pol item was improved to interpret the hysteretic phenomena of SMA, and the nonlinear dynamic model of SMA intravascular stent under radial stochastic loads was developed. The conditions of stochastic stability of the system were obtained in singular boundary theory. The steady-state probability density function of the dynamic response of the system was given, and the stochastic Hopf bifurcation characteristics of the system were analyzed. Theoretical analysis and numerical simulation show that the stability of the trivial solution varies with bifurcation parameters, and stochastic Hopf bifurcation appears in the process, which can cause stent fracture or loss. The results of this paper are helpful to application of SMA intravascular stent in biomedical engineering fields.

  5. Effects of fundamental structure parameters on dynamic responses of submerged floating tunnel under hydrodynamic loads

    Institute of Scientific and Technical Information of China (English)

    Xu Long; Fei Ge; Lei Wang; Youshi Hong

    2009-01-01

    This paper investigates the effects of structure parameters on dynamic responses of submerged floating tunnel (SFT) under hydrodynamic loads. The structure parameters includes buoyancy-weight ratio (BWR), stiffness coefficients of the cable systems, tunnel net buoyancy and tunnel length. First, the importance of structural damp in relation to the dynamic responses of SFT is demonstrated and the mechanism of structural damp effect is discussed. Thereafter, the fundamental structure parameters are investi-gated through the analysis of SFT dynamic responses under hydrodynamic loads. The results indicate that the BWR of SFT is a key structure parameter. When BWR is 1.2, there is a remarkable trend change in the vertical dynamic response of SFT under hydrodynamic loads. The results also indicate that the ratio of the tunnel net buoyancy to the cable stiffness coefficient is not a characteristic factor affecting the dynamic responses of SFT under hydrodynamic loads.

  6. Analysis of low energy arc discharge characteristics based on dynamic V-A characteristics model

    Institute of Scientific and Technical Information of China (English)

    JING Li-nan; WANG Li-gong

    2006-01-01

    Low energy arc discharge characteristics was analyzed based on dynamic V-A characteristics model. It draws conclusions that discharge time relates to the source voltage and the product of inductance and stable current, discharge time will increase when the source voltage increases; current reduce rate is in inverse proportion to the value of inductance; arc resistance when the arc occurs is the ratio of minimum arcing voltage to stable current. It also gains the expressions of arc resistance and arc power, arc resistance and arc power both increase as the source voltage increases and decrease as the value of inductance increases. Conclusions above mentioned are helpful to design intrinsically safe circuits.

  7. Dynamic characteristics of hydraulic power steering system with accumulator in load-haul-dump vehicle

    Institute of Scientific and Technical Information of China (English)

    杨忠炯; 何清华; 柳波

    2004-01-01

    Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and discussed with SIMULINK software and hydraulic control theory. The results show that the dynamic characteristics of hydraulic power steering system are improved obviously by using bladder accumulator, the hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle generates vibration at the initial stage under the normal steering condition of pulse input, and its static response time is 0.25 s shorter than that without bladder accumulator. Under the normal steering working condition, the capacity of steering accumulator for absorbing pulse is directly proportional to the cross section area of connecting pipeline, and inversely proportional to the length of connecting pipeline. At the same time, the precharge pressure of nitrogen in steering accumulator should be 60%- 80% of the rated minimum working pressure of hydraulic power steering system. Under the abnormal steering working condition, the steering cylinder piston may obtain higher motion velocity, and the dynamic response velocity of hydraulic power steering system can be increased by reducing the pressure drop of hydraulic pipelines between the accumulator and steering cylinder and by increasing the rated pressure of hydraulic power steering system, but the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle have nothing to do with the precharge pressure of nitrogen in steering accumulator.

  8. Photonic water dynamically responsive to external stimuli

    Science.gov (United States)

    Sano, Koki; Kim, Youn Soo; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Aida, Takuzo

    2016-08-01

    Fluids that contain ordered nanostructures with periodic distances in the visible-wavelength range, anomalously exhibit structural colours that can be rapidly modulated by external stimuli. Indeed, some fish can dynamically change colour by modulating the periodic distance of crystalline guanine sheets cofacially oriented in their fluid cytoplasm. Here we report that a dilute aqueous colloidal dispersion of negatively charged titanate nanosheets exhibits structural colours. In this `photonic water', the nanosheets spontaneously adopt a cofacial geometry with an ultralong periodic distance of up to 675 nm due to a strong electrostatic repulsion. Consequently, the photonic water can even reflect near-infrared light up to 1,750 nm. The structural colour becomes more vivid in a magnetic flux that induces monodomain structural ordering of the colloidal dispersion. The reflective colour of the photonic water can be modulated over the entire visible region in response to appropriate physical or chemical stimuli.

  9. Dynamic response of Hovercraft lift fans

    Science.gov (United States)

    Moran, D. D.

    1981-08-01

    Hovercraft lift fans are subjected to varying back pressure due to wave action and craft motions when these vehicles are operating in a seaway. The oscillatory back pressure causes the fans to perform dynamically, exhibiting a hysteresis type of response and a corresponding degradation in mean performance. Since Hovercraft motions are influenced by variations in lift fan pressure and discharge, it is important to understand completely the nature of the dynamic performance of lift fans in order to completely solve the Hovercraft seakeeping problem. The present study was performed to determine and classify the instabilities encountered in a centrifugal fan operating against time-varying back pressure. A model-scale experiment was developed in which the fan discharge was directed into a flow-measuring device, terminating in a rotating valve which produced an oscillatory back pressure superimposed upon a mean aerodynamic resistance. Pressure and local velocity were measured as functions of time at several locations in the fan volute. The measurements permitted the identification of rotating (or propagating) stall in the impeller. One cell and two cell configurations were classified and the transient condition connecting these two configurations was observed. The mechanisms which lead to rotating stall in a centrifugal compressor are presented and discussed with specific reference to Hovercraft applications.

  10. Research on Frequency Response Characteristics of Rolling Mill

    Institute of Scientific and Technical Information of China (English)

    CaiZhengguo; ZhangKenan

    2005-01-01

    The measurement method of frequency response characteristics for rolling mill is established by imposing different signal excitation on PID input of rolling mill under the different rolling conditions. The analysis results declare that sweep sine signal was relative efficient to evaluation for the frequency response character of hydraulic system. The practical application shows that the corresponding relationship between the parameters and the frequency response range of the rolling mill is helpful for parameters verification of process control and condition monitoring of hydraulic system.

  11. Hydroelastic dynamic characteristics of a slender axis-symmetric body

    Science.gov (United States)

    Chen, Weimin; Li, Min; Zheng, Zhongqin; Zhang, Liwu

    2010-07-01

    The slender axis-symmetric submarine body moving in the vertical plane is the object of our investigation. A coupling model is developed where displacements of a solid body as a Euler beam (consisting of rigid motions and elastic deformations) and fluid pressures are employed as basic independent variables, including the interaction between hydrodynamic forces and structure dynamic forces. Firstly the hydrodynamic forces, depending on and conversely influencing body motions, are taken into account as the governing equations. The expressions of fluid pressure are derived based on the potential theory. The characteristics of fluid pressure, including its components, distribution and effect on structure dynamics, are analyzed. Then the coupling model is solved numerically by means of a finite element method (FEM). This avoids the complicacy, combining CFD (fluid) and FEM (structure), of direct numerical simulation, and allows the body with a non-strict ideal shape so as to be more suitable for practical engineering. An illustrative example is given in which the hydroelastic dynamic characteristics, natural frequencies and modes of a submarine body are analyzed and compared with experimental results. Satisfactory agreement is observed and the model presented in this paper is shown to be valid.

  12. Hydroelastic dynamic characteristics of a slender axis-symmetric body

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The slender axis-symmetric submarine body moving in the vertical plane is the object of our investigation.A coupling model is developed where displacements of a solid body as a Euler beam(consisting of rigid motions and elastic deformations) and fluid pressures are employed as basic independent variables,including the interaction between hydrodynamic forces and structure dynamic forces.Firstly the hydrodynamic forces,depending on and conversely influencing body motions,are taken into account as the governing equations.The expressions of fluid pressure are derived based on the potential theory.The characteristics of fluid pressure,including its components,distribution and effect on structure dynamics,are analyzed.Then the coupling model is solved numerically by means of a finite element method(FEM).This avoids the complicacy,combining CFD(fluid) and FEM(structure),of direct numerical simulation,and allows the body with a non-strict ideal shape so as to be more suitable for practical engineering.An illustrative example is given in which the hydroelastic dynamic characteristics,natural frequencies and modes of a submarine body are analyzed and compared with experimental results.Satisfactory agreement is observed and the model presented in this paper is shown to be valid.

  13. Preliminary study on variation characteristics of ocean tide dynamic stress in crust and its relationship with earthquakes

    Institute of Scientific and Technical Information of China (English)

    LU Ming-yong; ZHENG Wen-heng

    2005-01-01

    The variation characteristics of dynamic stress in crustal blocks and its relationship with earthquakes are comprehensively studied by analyzing geophysical data and calculating the dynamic response of crustal blocks in North China to the tide level change of Bohai Sea and Yellow Sea using a 3D nonlinear dynamic finite element simulation. This study has noticed some new features of crustal dynamic stress: (a) High stress level appears at the place where the stress waves superpose and interference during the process of propagation, and the enhancement of dynamic shear stress is more significant as compared with that of compressive stress; (b) Variation of dynamic stress has influence on seismogenic environment and hence earthquake occurrence; (c) As viewed from the variation characteristics of crustal dynamic stress, the superimposing process of shear stress manifests the preparation process of earthquakes.

  14. Response and Reliability Problems of Dynamic Systems

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present thesis consists of selected parts of the work performed by the author on stochastic dynamics and reliability theory of dynamically excited structures primarily during the period 1986-1996.......The present thesis consists of selected parts of the work performed by the author on stochastic dynamics and reliability theory of dynamically excited structures primarily during the period 1986-1996....

  15. Study on dynamic characteristics of coupled model for deep-water lifting system

    Science.gov (United States)

    Wu, Yunxia; Lu, Jianhui; Zhang, Chunlei

    2016-10-01

    The underwater installation of marine equipment in deep-water development requires safe lifting and accurate positioning. The heave compensation system is an important technology to ensure normal operation and improve work accuracy. To provide a theoretical basis for the heave compensation system, in this paper, the continuous modeling method is employed to build up a coupled model of deep-water lifting systems in vertical direction. The response characteristics of dynamic movement are investigated. The simulation results show that the resonance problem appears in the process of the whole releasing load, the lifting system generates resonance and the displacement response of the lifting load is maximal when the sinking depth is about 2000 m. This paper also analyzes the main influencing factors on the dynamic response of load including cable stiffness, damping coefficient of the lifting system, mass and added mass of lifting load, among which cable stiffness and damping coefficient of the lifting system have the greatest influence on dynamic response of lifting load when installation load is determined. So the vertical dynamic movement response of the load is reduced by installing a damper on the lifting cable and selecting the appropriate cable stiffness.

  16. Achieving Reliable Communication in Dynamic Emergency Responses

    Science.gov (United States)

    Chipara, Octav; Plymoth, Anders N.; Liu, Fang; Huang, Ricky; Evans, Brian; Johansson, Per; Rao, Ramesh; Griswold, William G.

    2011-01-01

    Emergency responses require the coordination of first responders to assess the condition of victims, stabilize their condition, and transport them to hospitals based on the severity of their injuries. WIISARD is a system designed to facilitate the collection of medical information and its reliable dissemination during emergency responses. A key challenge in WIISARD is to deliver data with high reliability as first responders move and operate in a dynamic radio environment fraught with frequent network disconnections. The initial WIISARD system employed a client-server architecture and an ad-hoc routing protocol was used to exchange data. The system had low reliability when deployed during emergency drills. In this paper, we identify the underlying causes of unreliability and propose a novel peer-to-peer architecture that in combination with a gossip-based communication protocol achieves high reliability. Empirical studies show that compared to the initial WIISARD system, the redesigned system improves reliability by as much as 37% while reducing the number of transmitted packets by 23%. PMID:22195075

  17. Dynamic response of dry and water-saturated sand systems

    Science.gov (United States)

    LaJeunesse, J. W.; Hankin, M.; Kennedy, G. B.; Spaulding, D. K.; Schumaker, M. G.; Neel, C. H.; Borg, J. P.; Stewart, S. T.; Thadhani, N. N.

    2017-07-01

    The effect of grain size and moisture content on the dynamic macroscopic response of granular geological materials was explored by performing uniaxial planar impact experiments on high purity, Oklahoma #1, sand samples composed of either fine (75-150 μm) or coarse (425-500 μm) grain sizes in either dry or fully water-saturated conditions. Oklahoma #1 sand was chosen for its smooth, quasi-spherical grain shapes, narrow grain size distributions, and nearly pure SiO2 composition (99.8 wt. %). The water-saturated samples were completely saturated ensuring a two-phase mixture with roughly 65% sand and 35% water. Sand samples were dynamically loaded to pressures between 1 and 11 GPa. Three-dimensional meso-scale simulations using an Eulerian hydrocode, CTH, were created to model the response of each sand sample. Multi-phase equations of state were used for both silicon dioxide, which comprised individual sand grains, and water, which surrounded individual grains. Particle velocity profiles measured from the rear surface of the sand, both experimentally and computationally, reveal that fine grain samples have steeper rise characteristics than coarse grain samples and water-saturated samples have an overall much stiffer response than dry samples. The experimentally determined particle velocity vs. shock velocity response of dry sand was linear over this pressure range, with little difference between the two grain sizes investigated. The experimental response for the water saturated sand exhibited a piecewise continuous response with a transition region between particle velocities of 0.6 km s-1 and 0.8 km s-1 and a pressure of 4.5-6 GPa. Hypotheses for the cause of this transition region are drawn based on results of the meso-scale simulations.

  18. Quantifying dynamic characteristics of human walking for comprehensive gait cycle.

    Science.gov (United States)

    Mummolo, Carlotta; Mangialardi, Luigi; Kim, Joo H

    2013-09-01

    Normal human walking typically consists of phases during which the body is statically unbalanced while maintaining dynamic stability. Quantifying the dynamic characteristics of human walking can provide better understanding of gait principles. We introduce a novel quantitative index, the dynamic gait measure (DGM), for comprehensive gait cycle. The DGM quantifies the effects of inertia and the static balance instability in terms of zero-moment point and ground projection of center of mass and incorporates the time-varying foot support region (FSR) and the threshold between static and dynamic walking. Also, a framework of determining the DGM from experimental data is introduced, in which the gait cycle segmentation is further refined. A multisegmental foot model is integrated into a biped system to reconstruct the walking motion from experiments, which demonstrates the time-varying FSR for different subphases. The proof-of-concept results of the DGM from a gait experiment are demonstrated. The DGM results are analyzed along with other established features and indices of normal human walking. The DGM provides a measure of static balance instability of biped walking during each (sub)phase as well as the entire gait cycle. The DGM of normal human walking has the potential to provide some scientific insights in understanding biped walking principles, which can also be useful for their engineering and clinical applications.

  19. Charge dynamic characteristics in corona-charged polytetrafluoroethylene film electrets

    Institute of Scientific and Technical Information of China (English)

    陈钢进; 肖慧明; 朱春凤

    2004-01-01

    In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and thermal stimulating surface-potential decay measurements. The results showed that the initial surface potential, whether positively or negatively charging, is much higher in non-porous PTFE than in porous PTFE. For porous film the value of initial sur-face potentials increases with increase of film thickness. Higher charging temperature can remarkably improve charge stability. The charge dynamics are correlated to materials microstructure according to their scanning electron micrographs.For non-porous PTFE films, polarizability change of C-F bonds is the main origin of electret charges; but for porous PTFE film a large number of bulk and interface type traps are expected because of the greater area of interface and higher crys-tallinity.

  20. Charge dynamic characteristics in corona-charged polytetrafluoroethylene film electrets

    Institute of Scientific and Technical Information of China (English)

    陈钢进; 肖慧明; 朱春凤

    2004-01-01

    In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and thermal stimulating surface-potential decay measurements. The results showed that the initial surface potential, whether positively or negatively charging, is much higher in non-porous PTFE than in porous PTFE. For porous film the value of initial surface potentials increases with increase of film thickness. Higher charging temperature can remarkably improve charge stability. The charge dynamics are correlated to materials microstructure according to their scanning electron micrographs.For non-porous PTFE films, polarizability change of C-F bonds is the main origin of electret charges; but for porous PTFE film a large number of bulk and interface type traps are expected because of the greater area of interface and higher crystallinity.

  1. 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.

  2. Transient response characteristics in a biomolecular integral controller.

    Science.gov (United States)

    Sen, Shaunak

    2016-04-01

    The cellular behaviour of perfect adaptation is achieved through the use of an integral control element in the underlying biomolecular circuit. It is generally unclear how integral action affects the important aspect of transient response in these biomolecular systems, especially in light of the fact that it typically deteriorates the transient response in engineering contexts. To address this issue, the authors investigated the transient response in a computational model of a simple biomolecular integral control system involved in bacterial signalling. They find that the transient response can actually speed up as the integral gain parameter increases. On further analysis, they find that the underlying dynamics are composed of slow and fast modes and the speed-up of the transient response is because of the speed-up of the slow-mode dynamics. Finally, they note how an increase in the integral gain parameter also leads to a decrease in the amplitude of the transient response, consistent with the overall improvement in the transient response. These results should be useful in understanding the overall effect of integral action on system dynamics, particularly for biomolecular systems.

  3. 桥梁在役桩的竖向动力响应特性及损伤识别研究%Study on Vertical Dynamic Response Characteristics and Damage Identification of Existing Bridge Pile

    Institute of Scientific and Technical Information of China (English)

    卢韦男; 张鸿儒

    2014-01-01

    Integrity detection of the pile foundations of existing structures is a difficult problem worldwide.Integrity testing of newly constructed pile foundations includes detection methods such as mining with the observation method,drilling core method,low-strain test method,and ultra-sonic method.However,for damage detection of pile foundations in service,the existence of plat-forms and bridge structures above pile foundations makes the observation method difficult be-cause the mining depth of the soil around the pile is very limited.Drilling core methods cannot be achieved because drill core must be drilled from the pile top.For ultrasonic detection,there is no channel available for installing ultrasonic transducers.For the low-strain test method,velocity sen-sors cannot be placed at the top of the pile;therefore,vertical vibration cannot be recorded.In this paper,vertical impact load is applied on the upper cap surface above the detected pile.According to the vertical velocity response of the cap surface and pile head,we analyze the integrity of the bridge pile foundation in-service. Bridge pier-cap-pile-soil explicit dynamic finite element models are based on ANSYS LS-DY-NA.In the finite element models,impact load is applied on the cap surface,and the vertical veloci-ty responses of the complete pile and the cracked pile are both recorded.Two types of pier-cap-pile-soil numerical models are used in this study with six and eight piles,respectively.The results show that when the impact load is applied at the cap surface on top of the pile to be detected,the stress wave goes through the cap and propagates downward along the pile.Similar to the principle of sonic echo in pile integrity testing,the stress wave reflects at the pile bottom or fracture surface where impedance changes significantly.From the vertical velocity response curve of the pile head, the reflected stress wave from the pile bottom or the fracture surface can be identified to deter-mine whether the pile

  4. Dynamic Characteristics of Supercavitating Flow Around a Hydrofoil

    Institute of Scientific and Technical Information of China (English)

    WANG Guo-yu(王国玉); ZHANG Mei-hong(张美红); LIU Shu-yan(刘淑艳); Ikohagi Toshiaki

    2004-01-01

    Supercavitation dynamic characteristics around a hydrofoil are studied with both high-speed visualization and drag and lift measurements. In the supercavitation condition, the cavitation area covers the entire surface of the foil. There is a distinct interface between the main flow and the supercavitating flow regions. The cavitating region is filled with cavitation bubble and water mixture. Small fluctuations of the interface are observed, which indicates that even a relative smooth surface is formed in this state, the interface is unsteady. The minimum drag is to be obtained in the supercavitation condition.

  5. NONLINEAR DYNAMICAL CHARACTERISTICS OF PILES UNDER HORIZONTAL VIBRATION

    Institute of Scientific and Technical Information of China (English)

    HU Yu-jia; CHENG Chang-jun; YANG Xiao

    2005-01-01

    The pile-soil system is regarded as a visco-elastic half-space embedded pile. Based on the method of continuum mechanics, a nonlinear mathematical model of pilesoil interaction was established-a coupling nonlinear boundary value problem. Under the case of horizontal vibration, the nonlinearly dynamical characteristics of pile applying the axis force were studied in horizontal direction in frequency domain. The effects of parameters, especially the axis force on the stiffness were studied in detail. The numerical results suggest that it is possible that the pile applying an axis force will lose its stability. So, the effect of the axis force on the pile is considered.

  6. SOFTWARE TESTING OF THE RAIL VEHICLE DYNAMIC CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    Sanjin Troha

    2015-08-01

    Full Text Available The modern construction concept and the determination of the machine system characteristics anticipate CAD design. Creating model that will be tested using FEM and other methods for determining stress-strain is a very important part of rail vehicle construction. Applicative software package consists of linear and non–linear methods for the prediction of railway vehicle behavior and various methods of analysis have been assembled into a single coherent package in order to allow real problems in railway vehicle dynamics to be solved.

  7. Analysis for the Dynamic Characteristic of the Automobile Transmission Gearbox

    Directory of Open Access Journals (Sweden)

    Fujin Yu

    2013-02-01

    Full Text Available Automobile transmission gearbox, as one of the major components, which will inevitably bring about the vibration and noise of automobile vehicle. The objective of this study to reduce the noise and vibration of automobile transmission by structural optimization of the gearbox in order to better control its functional operation and improve its performance. For this purpose, based on the working characteristics of the gearbox, modal analysis of automobile transmission gearbox is formulated using 3D graphics software Pro/E together with Finite Element Method. In addition, the modal test of gearbox is conducted also. Through comparing model analysis results to test results, test results verify the correctness of the finite element analysis results, thus provide the theoretic basis to analyze its dynamic characteristics of the gearbox structure as well as its improvement to reduce vibration and noise.

  8. A Study on the Dynamic Characteristics of HANARO Test Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Shin; Choi, M. H.; Song, S. Y. [Chungnam National University, Taejon (Korea, Republic of)

    1997-06-01

    A study on the dynamic characteristics of Type-B irradiation test fuel to be used on HANARO in-core are performed. To generate the valid finite element model, in-air vibration test is also performed, and the natural frequency and displacement of the Type-B fuel assembly are measured by in-core vibration test on HANARO. From the experimental and FEM results, the displacement in the top of test hole is predicted. The stress and fatigue analysis are conducted by static analysis using a finite element program. Finally, the effects on the mass and stiffness of the guide tube are evaluated for improvement of the vibration characteristics of the Type-B test Fuel. 9 refs., 22 tabs., 25 figs. (author)

  9. Dynamic Characteristics Analysis of the Coupled Lateral-Torsional Vibration with Spur Gear System

    Directory of Open Access Journals (Sweden)

    Shihua Zhou

    2015-01-01

    Full Text Available A sixteen-degree-of-freedom (16-DOF lumped parameter dynamic model taking into account the gravity, eccentricity, bearing clearance, transmission error, and coupled lateral-torsional vibration is established. Based on the dynamical equation, the dynamic behaviors of the spur gear rotor bearing system are investigated by using Runge-Kutta method. The research focuses on the effect of rotational speed, eccentricity, and bearing clearance and nonlinear response of the coupled multibody dynamics is presented by vibration waveform, spectrum, and 3D frequency spectrum. The results show that the rotational frequency of the driven gear appears in the driving gear, and the dynamic characteristics of gears have obvious differences due to the effects of the gear assembly and the coupled lateral-torsional vibration. The bearing has its own resonance frequency, and the effect of the variable stiffness frequency of the bearings should be avoided during the system design. The results presented in this paper show an analysis of the coupled lateral-torsional vibration of the spur gear system. The study may contribute to a further understanding of the dynamic characteristics of such a spur gear rotor bearing system.

  10. 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.

  11. Dynamic Multiaxial Response of a Hot-Pressed Aluminum Nitride

    Science.gov (United States)

    2012-01-05

    Dynamic Multiaxial Response of a Hot-Pressed Aluminum Nitride by Guangli Hu, C. Q. Chen, K. T. Ramesh, and J. W. McCauley ARL-RP-0487...Laboratory Aberdeen Proving Ground, MD 21005-5066 ARL-RP-0487 June 2014 Dynamic Multiaxial Response of a Hot-Pressed Aluminum Nitride...3. DATES COVERED (From - To) January 2010–January 2013 4. TITLE AND SUBTITLE Dynamic Multiaxial Response of a Hot-Pressed Aluminum Nitride 5a

  12. 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.

  13. [Adsorption dynamics and breakthrough characteristics based on the fluidization condition].

    Science.gov (United States)

    Wang, Jun; Wang, Yao; Huang, Xing; Yuan, Yi-Long; Chen, Rui-Hui; Zhou, Hang; Zhou, Dan-Dan

    2014-02-01

    Few studies on the adsorption dynamics and breakthrough characteristics based on the fluidization condition have been reported. In a fluidized bed adsorption reactor with phenol as the adsorbate and granular activated carbon as the adsorbent, the adsorption efficiency, adsorption dynamic characteristics, adsorption breakthrough curves and adsorption capacities were studied and compared with those of a fixed bed operated under the same conditions. The results showed that the adsorption efficiencies exceeded 93% in 5 min in both the fluidized conditions and fixed conditions at the superficial velocities of 8 mm x s(-1) and 13 mm x s(-1). Meanwhile, the above adsorption reactions fitted to Pseudo-second-order with linear correlation coefficients greater than 0.999. The adsorption capacity of fluidized conditions was 8.77 mg x g(-1) and 24.70 mg x g(-1) at the superficial velocities of 6 mm x s(-1) and 8 mm x s(-1). Generally, the fluidized bed reactor showed a higher adsorption efficiency and greater adsorption capacity than the fixed bed reactor.

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

    Directory of Open Access Journals (Sweden)

    Löcken F.

    2015-02-01

    Full Text Available 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.

  15. RESPONSE CHARACTERISTICS OF WIND EXCITED CABLES WITH ARTIFICIAL RIVULET

    Institute of Scientific and Technical Information of China (English)

    顾明; 刘慈军; 徐幼麟; 项海帆

    2002-01-01

    A wind tunnel investigation of response characteristics of cables with artificial rivulet is presented.A series of cable section models of different mass and stiffness and damping ratio were designed with artificial rivulet.They were tested in smooth flow under different wind speed and yaw angle and for different position of artificial rivulet.The measured response of cable models was then analyzed and compared with the experimental results obtained by other researchers and the existing theories for wind-induced cable vibration.The results show that the measured response of horizontal cable models with artificial rivulet could be well predicted by Den Hartog' s galloping theory when wind is normal to the cable axis.For the wind with certain yaw angles, the cable models with artificial rivulet exhibit velocity-restricted response characteristics.

  16. SC response characteristics of two kinds of coagulant

    Institute of Scientific and Technical Information of China (English)

    杨万东; 宋爽; 史惠祥

    2002-01-01

    Automatic coagulant dosage control with streaming current (SC) technique is introduced in this paper. Aluminum and ferric coagulants are widely used in surface water treatment. The SC response characteristics of P-AlCl3 aluminum coagulant and P-FeCl3 ferric coagulant were investigated in this work. Bench-scale water treatment results were obtained from jar tests including rapid mixing, flocculation and undisturbed sedimentation. Results showed that aluminum coagulant is more sensitive than ferric coagulant to SC response.

  17. SC response characteristics of two kinds of coagulant

    Institute of Scientific and Technical Information of China (English)

    杨万东; 宋爽; 史惠祥

    2002-01-01

    Automatic coagulant dosage control with streaming current (SC) technique is in troduced inthis paper. Aluminum and ferric coagulants are widely used in surface water treatment. The SC response characteristics of P-AiCI3 aluminum coagulant and P-FeCI3 ferric coagulant were investigated in this work. Bench-scale water treatment results were obtained from jar tests including rapid mixing,flocculation and undisturbed sedimentation. Results showed that aluminum coagulant is more sensitive than ferric coagulant to SC response.

  18. Influence of construction interfaces on dynamic characteristics of roller compacted concrete dams

    Institute of Scientific and Technical Information of China (English)

    顾冲时; 王少伟; 包腾飞

    2015-01-01

    To study the influence of construction interfaces on dynamic characteristics of roller compacted concrete dams (RCCDs), mechanical properties of construction interfaces are firstly analyzed. Then, the viscous-spring artificial boundary (VSAB) is adopted to simulate the radiation damping of their infinite foundations, and based on the Marc software, a simplified seismic motion input method is presented by the equivalent nodal loads. Finally, based on the practical engineering of a RCC gravity dam, effects of radiation damping and construction interfaces on the dynamic characteristics of dams are investigated in detail. Analysis results show that dynamic response of the RCC gravity dam significantly reduces about 25%when the radiation damping of infinite foundation is considered. Hot interfaces and the normal cold interfaces have little influence on the dynamic response of the RCC gravity dam. However, nonlinear fracture along the cold interfaces at the dam heel will occur under the designed earthquake if the cold interfaces are combined poorly. Therefore, to avoid the fractures along the construction interfaces under the potential super earthquakes, combination quality of the RCC layers should be significantly ensured.

  19. Dynamic bioactive stimuli-responsive polymeric surfaces

    Science.gov (United States)

    Pearson, Heather Marie

    This dissertation focuses on the design, synthesis, and development of antimicrobial and anticoagulant surfaces of polyethylene (PE), polypropylene (PP), and poly(tetrafluoroethylene) (PTFE) polymers. Aliphatic polymeric surfaces of PE and PP polymers functionalized using click chemistry reactions by the attachment of --COOH groups via microwave plasma reactions followed by functionalization with alkyne moieties. Azide containing ampicillin (AMP) was synthesized and subsequently clicked into the alkyne prepared PE and PP surfaces. Compared to non-functionalized PP and PE surfaces, the AMP clicked surfaces exhibited substantially enhanced antimicrobial activity against Staphylococcus aureus bacteria. To expand the biocompatibility of polymeric surface anticoagulant attributes, PE and PTFE surfaces were functionalized with pH-responsive poly(2-vinyl pyridine) (P2VP) and poly(acrylic acid) (PAA) polyelectrolyte tethers terminated with NH2 and COOH groups. The goal of these studies was to develop switchable stimuli-responsive polymeric surfaces that interact with biological environments and display simultaneous antimicrobial and anticoagulant properties. Antimicrobial AMP was covalently attached to --COOH terminal ends of protected PAA, while anticoagulant heparin (HEP) was attached to terminal --NH2 groups of P2VP. When pH 5.5, they collapse while the PAA segments extend. Such surfaces, when exposed to Staphylococcus aureus, inhibit bacterial growth due to the presence of AMP, as well as are effective anticoagulants due to the presence of covalently attached HEP. Comparison of these "dynamic" pH responsive surfaces with "static" surfaces terminated with AMP entities show significant enhancement of longevity and surface activity against microbial film formation. The last portion of this dissertation focuses on the covalent attachment of living T1 and Φ11 bacteriophages (phages) on PE and PTFE surface. This was accomplished by carbodiimide coupling between --COOH

  20. Structural Nonlinear Flutter Characteristics Analysis for an Actuator-fin System with Dynamic Stiffness

    Institute of Scientific and Technical Information of China (English)

    YANG Ning; WU Zhigang; YANG Chao

    2011-01-01

    The flutter characteristics of an actuator-fin system are investigated with structural nonlinearity and dynamic stiffness of the electric motor.The component mode substitution method is used to establish the nonlinear governing equations in time domain and frequency domain based on the fundamental dynamic equations of the electric motor and decelerator.The existing describing function method and a proposed iterative method are used to obtain the flutter characteristics containing preload freeplay nonlinearity when the control command is zero.A comparison between the results of frequency domain and those of time domain is studied.Simulations are carried out when the control command is not zero and further analysis is conducted when the freeplay angle is changed.The results show that structural nonlinearity and dynamic stiffness have a significant influence on the flutter characteristics.Limit cycle oscillations(LCOs)are observed within linear flutter boundary.The response of the actuator-fin system is related to the initial disturbance.In the nonlinear condition,the amplitude of the control command has an influence on the flutter characteristics.

  1. Dynamic characteristics of two-phase thermal control system for spacecraft

    Science.gov (United States)

    Malozemov, Vladimir V.; Kudryavtseva, Natal'ya S.; Antonov, Viktor A.; Zagar, Oleg V.; Chernobaev, Nikolaj N.

    1992-07-01

    This paper deals with review of the issues associated with modelling the dynamic processes in the spacecraft two-phase thermal control systems. The work presents the results of modelling the nonstationary conditions of the evaporative and condensation heat exchangers functioning, investigates their response to the characteristic external influences. Disclosed are the results of the computer-aided modelling the two-phase thermal control system with a pump. The dynamic characteristics of the change in the inputs of pressures, temperatures and vapor content of a coolant in various branches of the system, as well as the lengths of the heat transfer zones in the evaporator and condenser under effect of the typical disturbing actions are obtained. The attained transients are analyzed.

  2. Dynamic Characteristic Analysis of Spinal Motor Control Between 11- and 15-Year-Old Children.

    Science.gov (United States)

    Chow, Daniel H; Lau, Newman M

    2016-07-01

    Spinal motor control can provide substantial insight for the causes of spinal musculoskeletal disorders. Its dynamic characteristics however, have not been fully investigated. The objective of this study is to explore the dynamic characteristics of spinal motor control via the fractional Brownian motion mathematical technique. Spinal curvatures and repositioning errors of different spinal regions in 64 children age 11- or 15-years old during upright stance were measured and compared for the effects of age and gender. With the application of the fractional Brownian motion analytical technique to the changes of spinal curvatures, distinct persistent movement behaviors could be determined, which could be interpreted physiologically as open-loop behaviors. Moreover, it was found that the spinal motor control of 15-year-old children was better than that of 11-year-old children with smaller repositioning error and less curvature variability as well as shorter response time and smaller curvature deformation.

  3. Dynamical theory of active cellular response to external stress

    Science.gov (United States)

    de, Rumi; Safran, Samuel A.

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  4. Dynamical theory of active cellular response to external stress.

    Science.gov (United States)

    De, Rumi; Safran, Samuel A

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  5. Characteristics and concepts of dynamic hub proteins in DNA processing machinery from studies of RPA.

    Science.gov (United States)

    Sugitani, Norie; Chazin, Walter J

    2015-03-01

    DNA replication, damage response and repair require the coordinated action of multi-domain proteins operating within dynamic multi-protein machines that act upon the DNA substrate. These modular proteins contain flexible linkers of various lengths, which enable changes in the spatial distribution of the globular domains (architecture) that harbor their essential biochemical functions. This mobile architecture is uniquely suited to follow the evolving substrate landscape present over the course of the specific process performed by the multi-protein machinery. A fundamental advance in understanding of protein machinery is the realization of the pervasive role of dynamics. Not only is the machine undergoing dynamic transformations, but the proteins themselves are flexible and constantly adapting to the progression through the steps of the overall process. Within this dynamic context the activity of the constituent proteins must be coordinated, a role typically played by hub proteins. A number of important characteristics of modular proteins and concepts about the operation of dynamic machinery have been discerned. These provide the underlying basis for the action of the machinery that reads DNA, and responds to and repairs DNA damage. Here, we introduce a number of key characteristics and concepts, including the modularity of the proteins, linkage of weak binding sites, direct competition between sites, and allostery, using the well recognized hub protein replication protein A (RPA).

  6. Nonlinear dynamic response of stay cables under axial harmonic excitation

    Institute of Scientific and Technical Information of China (English)

    Xu XIE; He ZHAN; Zhi-cheng ZHANG

    2008-01-01

    This paper proposes a new numerical simulation method for analyzing the parametric vibration of stay cables based on the theory of nonlinear dynamic response of structures under the asynchronous support excitation.The effects of important parameters related to parametric vibration of cables,I.e., characteristics of structure,excitation frequency,excitation amplitude,damping effect of the air and the viscous damping coefficient of the cables,were investigated by using the proposed method for the cables with significant length difference as examples.The analysis results show that nonlinear finite element method is a powerful technique in analyzing the parametric vibration of cables,the behavior of parametric vibration of the two cables with different Irvine parameters has similar properties,the amplitudes of parametric vibration of cables are related to the frequency and amplitude of harmonic support excitations and the effect of distributed viscous damping on parametric vibration of the cables is very small.

  7. Spontaneous Facial Mimicry in Response to Dynamic Facial Expressions

    Science.gov (United States)

    Sato, Wataru; Yoshikawa, Sakiko

    2007-01-01

    Based on previous neuroscientific evidence indicating activation of the mirror neuron system in response to dynamic facial actions, we hypothesized that facial mimicry would occur while subjects viewed dynamic facial expressions. To test this hypothesis, dynamic/static facial expressions of anger/happiness were presented using computer-morphing…

  8. Finite element analysis of dynamic response and structure borne noise of gearbox

    Institute of Scientific and Technical Information of China (English)

    LIU Wen; LIN Teng-jiao; LI Run-fang; DU Xue-song

    2007-01-01

    A dynamic finite element method combined with finite element mixed formula for contact problem is used to analyze the dynamic characteristics of gear system. Considering the stiffness excitation, error excitation and meshing shock excitation, the dynamic finite element model is established for the entire gear system which includes gears, shafts, bearings and gearbox housing. By the software of I-DEAS, the natural frequency, normal mode, dynamic time-domain response, frequency-domain response and one-third octave velocity grade structure borne noise of gear system are studied by the method of theoretical modal analysis and dynamic response analysis. The maximum values of vibration and structure borne noise are occurred at the mesh frequency of output grade gearing.

  9. 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.

  10. 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.

  11. RESEARCH ON MODELING AND CHARACTERISTICS OF THE SPINDLE DYNAMIC COUPLING ABSORBERING SYSTEM OF A SUPER-PRECISION SURFACE GRINDING MACHINE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The bearing is described by constrain matrix, and the spindle system of a NC surface grinding machine is simplified as elastic-coupling beam, then modal synthesis method is used to establish the dynamic model of beam.Moreover, the response of the end of rotor is analyzed, and the natural frequency, principle mode and other dynamic characteristics of the coupling system are studied, the law of bearing stiffness to coupling frequency and amplitude of rotor is also found.Finally, according to the actual condition, a dynamic absorber is designed.The simulation and experimental results show that the amplitude of spindle can be declined effectively when the dynamic absorber is attached.

  12. Dynamic characteristics of an inclined flexible cylinder undergoing vortex-induced vibrations

    Science.gov (United States)

    Han, Qinghua; Ma, Yexuan; Xu, Wanhai; Lu, Yan; Cheng, Ankang

    2017-04-01

    A series of experimental tests were conducted on vortex-induced vibrations (VIV) of a flexible inclined cylinder with a yaw angle equals 45° for investigating the response characteristics in a towing tank. The flexible cylinder model was 5.6 m in length and 16 mm in diameter with an aspect ratio of 350 and a mass ratio of 1.9. The Reynolds numbers ranged from about 800 to 16,000.The strain responses were measured directly in both cross-flow (CF) and in-line (IL) directions and corresponding displacements were obtained using a modal approach. The dynamic response characteristics of the inclined flexible cylinder excited by vortex shedding was examined from the aspect of strain response, displacement amplitudes, dominant modes, response frequencies and drag force coefficients. The experimental results indicated that the CF response amplitude could be up to a value of 3.0D and the IL one more than 1.1D. The dominant modes were from 1 to 3 in CF direction and 1 to 5 in IL direction. And it was found that dominant frequencies increased linearly with the reduced velocity. The multi-modal response of the flexible inclined cylinder model excited by VIV was observed and analyzed. Moreover, the values of drag coefficients were in the range of 0.9-2.6.

  13. Nonlinear dynamical model and response of avian cranial kinesis.

    Science.gov (United States)

    Meekangvan, Preeda; A Barhorst, Alan; Burton, Thomas D; Chatterjee, Sankar; Schovanec, Lawrence

    2006-05-01

    All modern birds have kinetic skulls in which the upper bill can move relative to the braincase, but the biomechanics and motion dynamics of cranial kinesis in birds are poorly understood. In this paper, we model the dynamics of avian cranial kinesis, such as prokinesis and proximal rhynchokinesis in which the upper jaw pivots around the nasal-frontal (N-F) hinge. The purpose of this paper is to present to the biological community an approach that demonstrates the application of sophisticated predictive mathematical modeling tools to avian kinesis. The generality of the method, however, is applicable to the advanced study of the biomechanics of other skeletal systems. The paper begins with a review of the relevant biological literature as well as the essential morphology of avian kinesis, especially the mechanical coupling of the upper and lower jaw by the postorbital ligament. A planar model of the described bird jaw morphology is then developed that maintains the closed kinematic topology of the avian jaw mechanism. We then develop the full nonlinear equations of motion with the assumption that the M. protractor pterygoideus and M. depressor mandibulae act on the quadrate as a pure torque, and the nasal frontal hinge is elastic with damping. The mechanism is shown to be a single degree of freedom device due to the holonomic constraints present in the quadrate-jugal bar-upper jaw-braincase-quadrate kinematic chain as well as the quadrate-lower jaw-postorbital ligament-braincase-quadrate kinematic chain. The full equations are verified via simulation and animation using the parameters of a Grey Heron (Ardea cinerea). Next we develop a simplified analytical model of the equations by power series expansion. We demonstrate that this model reproduces the dynamics of the full model to a high degree of fidelity. We proceed to use the harmonic balance technique to develop the frequency response characteristics of the jaw mechanism. It is shown that this avian cranial

  14. Measurement of dynamic characteristics of metal sheet under laser shock

    Institute of Scientific and Technical Information of China (English)

    Hongbing Yao; Zhusheng Zhou; Bo Xing; Guilin Ding; Yanqun Tong; Jie Ping; Liangwan Li; Yongkang Zhang

    2012-01-01

    A new approach is developed to measure the dynamic characteristics of metal sheet under laser shock,including deformation velocity,strain,and strain rate.The detecting laser beam is partially shaded by the target deformation induced by the laser action.A photodiode transforms the received beam intensity real time into an electrical signal which could record the process of the target deformation.The functional relation between the electrical signal and the deformation of the metal sheet is derived.The deformation curve of a thin aluminum and the velocity curve of its deformation are also obtained during the experiment.The results indicate that the average velocity of the elastic deformation of the target can reach 2.999×103 m/s in the central area.This new method provides an approach in the study of the effect of strain rate on deformation.

  15. 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.

  16. Dynamic Response Analysis of Microflow Electrochemical Sensors with Two Types of Elastic Membrane.

    Science.gov (United States)

    Zhou, Qiuzhan; Wang, Chunhui; Chen, Yongzhi; Chen, Shuozhang; Lin, Jun

    2016-05-09

    The Molecular Electric Transducer (MET), widely applied for vibration measurement, has excellent sensitivity and dynamic response at low frequencies. The elastic membrane in the MET is a significant factor with an obvious effect on the performance of the MET in the low frequency domain and is the focus of this paper. In simulation experiments, the elastic membrane and the reaction cavity of the MET were analysed in a model based on the multiphysics finite element method. Meanwhile, the effects caused by the elastic membrane elements are verified in this paper. With the numerical simulation and practical experiments, a suitable elastic membrane can be designed for different cavity structures. Thus, the MET can exhibit the best dynamic response characteristics to measure the vibration signals. With the new method presented in this paper, it is possible to develop and optimize the characteristics of the MET effectively, and the dynamic characteristics of the MET can be improved in a thorough and systematic manner.

  17. Dynamics of Stride Interval Characteristics during Continuous Stairmill Climbing

    Science.gov (United States)

    Raffalt, Peter C.; Vallabhajosula, Srikant; Renz, Jessica J.; Mukherjee, Mukul; Stergiou, Nicholas

    2017-01-01

    It has been shown that statistical persistence in stride intervals characteristics exist during walking, running and cycling and were speed-dependent among healthy young adults. The purpose of this study was to determine if such statistical persistence in stride time interval, stride length and stride speed also exists during self-paced continuous stairmill climbing and if the strength is dependent on stepping rate. Stride time, stride length, and stride speed were collected from nine healthy participants during 3 min of stairmill climbing at 100, 110, and 120% of their preferred stepping rate (PSR) and 5 min of treadmill walking at preferred walking speed (PWS). The amount of variability (assessed by standard deviation and coefficient of variation) and dynamics (assessed by detrended fluctuation analysis and sample entropy) of the stride time, stride length, and stride speed time series were investigated. The amounts of variability were significantly higher during stairmill climbing for the stride time, stride length, and stride speed and did only change with increased stepping rate for stride speed. In addition to a more irregular pattern during stairmill climbing, the detrended fluctuation analysis (DFA) revealed that the stride length fluctuations were statistical anti-persistent for all subjects. On a group level both stride time and stride speed fluctuations were characterized by an uncorrelated pattern which was more irregular compared to that during treadmill walking. However, large inter-participant differences were observed for these two variables. In addition, the dynamics did not change with increase in stepping rate. PMID:28878688

  18. 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.

  19. 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.

  20. Dynamical Response of Networks Under External Perturbations: Exact Results

    Science.gov (United States)

    Chinellato, David D.; Epstein, Irving R.; Braha, Dan; Bar-Yam, Yaneer; de Aguiar, Marcus A. M.

    2015-04-01

    We give exact statistical distributions for the dynamic response of influence networks subjected to external perturbations. We consider networks whose nodes have two internal states labeled 0 and 1. We let nodes be frozen in state 0, in state 1, and the remaining nodes change by adopting the state of a connected node with a fixed probability per time step. The frozen nodes can be interpreted as external perturbations to the subnetwork of free nodes. Analytically extending and to be smaller than 1 enables modeling the case of weak coupling. We solve the dynamical equations exactly for fully connected networks, obtaining the equilibrium distribution, transition probabilities between any two states and the characteristic time to equilibration. Our exact results are excellent approximations for other topologies, including random, regular lattice, scale-free and small world networks, when the numbers of fixed nodes are adjusted to take account of the effect of topology on coupling to the environment. This model can describe a variety of complex systems, from magnetic spins to social networks to population genetics, and was recently applied as a framework for early warning signals for real-world self-organized economic market crises.

  1. EVALUATION ON THE SEISMIC RESPONSE CHARACTERISTICS OF A ROAD EMBANKMENT BASED ON THE MODERATE EARTHQUAKE OBSERVATION AND THE MICROTREMOR MEASUREMENT

    Science.gov (United States)

    Hata, Yoshiya; Ichii, Koji; Yamada, Masayuki; Tokida, Ken-Ichi; Takezawa, Koichiro; Shibao, Susumu; Mitsushita, Junji; Murata, Akira; Furukawa, Aiko; Koizumi, Keigo

    Accurate evaluation on the seismic response characteristics of a road embankment is very important for the rational seismic assessment. However, in a lot of previous studies, the seismic response characteristics of an embankment were evaluated based on the results of shaking table test, centrifuge model test and dynamic FEM analysis. In this study, the transfer function and the shear wave velocity of a road embankment were evaluated based on the in-situ records of moderate earthquake observation and microtremor measurement. Test results show the possibility that the shear wave velocity of an embankment can be estimated by the earthquake observation or the microtremor measurement and the dynamic linear FEM analysis.

  2. Dynamic characteristics of power-tower space stations with 15-foot truss bays

    Science.gov (United States)

    Dorsey, J. T.

    1986-01-01

    A power tower space station concept which generates power with photovoltaic arrays and where the truss structure has a bay size of 15 ft is described. Rigid body and flexible body dynamic characteristics are presented for a 75-kW Initial Operating Capability (IOC) and 150-kW and 300-kW growth stations. The transient response of the IOC and 300-kW growth stations to shuttle dock, orbit reboost, and mobile remote manipulator system translation loads are studied. Displacements, accelerations, and bending moments at various locations on the IOC and 300-kW growth stations are presented.

  3. Vibration Response and Power Flow Characteristics of a Flexible Manipulator with a Moving Base

    Directory of Open Access Journals (Sweden)

    Yufei Liu

    2015-01-01

    Full Text Available Flexible manipulator generally can be modeled as a coupling system with a flexible beam and a rigid moving base. This paper investigates the vibration responses and power flow of a flexible manipulator with a moving base (FMMB. Considering the motion characteristics of the rigid base, the moving base is modeled to have a motion with disturbances, and the dynamic model of the FMMB is established. With the dynamic model, vibration responses of the FMMB for the rigid base having disturbance velocities and accelerations are specifically presented. Subsequently, to investigate the effect of the disturbances on the vibration energy distributions of the FMMB, power flow of the FMMB is exhibited. To verify the dynamic model, an ADAMS physical model of the FMMB is constructed. It reveals that the motion characteristics of the rigid base have a noticeable effect on the vibration responses and power flow of the FMMB and should be considered. The results are significant and contribute to the vibration control of flexible manipulators.

  4. Dynamic characteristics of a WPC-comparison of transfer matrix method and FE method

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-long; NIE Wu

    2003-01-01

    To find the difference in dynamic characteristics between conventional monohull ship and wave penetrating catamaran (WPC), a WPC was taken as an object; its dynamic characteristics were computed by transfer matrix method and finite element method respectively. According to the comparison of the nature frequency results and mode shape results, the fact that FEM method is more suitable to dynamic characteristics analysis of a WPC was pointed out, special features on dynamic characteristics of WPC were given, and some beneficial suggestions are proposed to optimize the strength of a WPC in design period.

  5. Dynamic response of cylindrical lined cavity in elastic medium

    Institute of Scientific and Technical Information of China (English)

    高盟; 王滢; 高广运

    2013-01-01

    An analytical solution to the transient dynamic response of a cylindrical lining subjected to an internal loading was presented and the dynamic interaction between the lining and surrounding soil was considered. The lining structure and the soil were treated as a cylindrical elastic shell and an infinite elastic compressible medium, respectively. A two-dimensional axisymmetric wave equation was derived from the governing equation of displacement by introducing the potential functions. Shell equation of motion was established based on continuity conditions. The closed-form solution for dynamic response of the lining due to an impact loading was obtained in Laplace transforms and inverse transforms. Detailed parametric studies were also presented to illustrate the influences of the Poisson ratio of soil, the dynamic shear moduli of both soil and lining and the thickness of lining on dynamic response of the lining.

  6. Cryoemission of Nitrous Oxide and Ethanol: Dynamic and Energy Characteristics

    Science.gov (United States)

    Drobyshev, A.; Strzhemechny, Yu.; Aldiyarov, A.; Korshikov, E.; Kurnosov, V.; Sokolov, D.

    2016-11-01

    We studied dynamic and spectral characteristics of light emission produced during cryodeposition of nitrous oxide and ethanol onto metal substrates at a temperature of 10 K and a pressure of a gas phase of 10^{-2} Torr. It was established that this radiation is comprised of a large number of individual flashes of varying amplitude, wavelength and duration. Our measurements indicated that for nitrous oxide the rise time required to reach the maximum intensity of a single flash is 0.015 × 10^{-3} s, whereas for ethanol such time is 0.3× 10^{-3} s (i.e., 20 times greater). We attribute such discrepancy to the significant difference between the intrinsic molecular dipole moments of nitrous oxide (μ = 0.097 D) and ethanol (μ = 1.68 D) . Emission spectra of both nitrous oxide and ethanol were measured in the wavelength range of 350-1050 nm. They consist of discrete peaks located at 517, 562, 690, 726, 805 and 866 nm for nitrous oxide and 387, 392, 822, 995 and 1019 nm for ethanol. To explain the obtained results, we consider two models based on the assumptions of existence of isomeric states of the nitrous oxide molecules, as well as of processes of molecular dipole ordering/disordering during cryodeposition from the gas phase.

  7. The Dynamical Characteristics and Wave Structure of Typhoon Rananim (2004)

    Institute of Scientific and Technical Information of China (English)

    MING Jie; NI Yunqi; SHEN Xinyong

    2009-01-01

    Typhoon Rananim (2004) was one of the severest typhoons landfalling the Chinese mainland from 1996 to 2004. It brought serious damage and induced prodigious economical loss. Using a new generation of mesoscale model, named the Weather Research and Forecasting (WRF) modeling system, with 1.667 km grid horizontal spacing on the finest nested mesh, Rananim was successfully simulated in terms of track, intensity, eye, eyewall, and spiral rainbands. We compared the structures of Rananim to those of hurricanes in previous studies and observations to assess the validity of simulation. The three-dimensional (3D) dynamic and thermal structures of eye and eyewall were studied based on the simulated results. The focus was investigation of the characteristics of the vortex Rossby waves in the inner-core region. We found that the Rossby vortex waves propagate azimuthally upwind against the azimuthal mean tangential flow around the eyewall, and their period was longer than that of an air parcel moving within the azimuthal mean tangential flow. They also propagated outward against the boundary layer inflow of the azimuthal mean vortex. Futhermore, we studied the connection between the spiral potential vorticity (PV) bands and spiral rainbands, and found that the vortex Rossby waves played an important role in the formation process of spiral rainbands.

  8. 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.

  9. Cryoemission of Nitrous Oxide and Ethanol: Dynamic and Energy Characteristics

    Science.gov (United States)

    Drobyshev, A.; Strzhemechny, Yu.; Aldiyarov, A.; Korshikov, E.; Kurnosov, V.; Sokolov, D.

    2017-04-01

    We studied dynamic and spectral characteristics of light emission produced during cryodeposition of nitrous oxide and ethanol onto metal substrates at a temperature of 10 K and a pressure of a gas phase of 10^{-2} Torr. It was established that this radiation is comprised of a large number of individual flashes of varying amplitude, wavelength and duration. Our measurements indicated that for nitrous oxide the rise time required to reach the maximum intensity of a single flash is 0.015 × 10^{-3} s, whereas for ethanol such time is 0.3× 10^{-3} s (i.e., 20 times greater). We attribute such discrepancy to the significant difference between the intrinsic molecular dipole moments of nitrous oxide (μ = 0.097 D) and ethanol (μ = 1.68 D). Emission spectra of both nitrous oxide and ethanol were measured in the wavelength range of 350-1050 nm. They consist of discrete peaks located at 517, 562, 690, 726, 805 and 866 nm for nitrous oxide and 387, 392, 822, 995 and 1019 nm for ethanol. To explain the obtained results, we consider two models based on the assumptions of existence of isomeric states of the nitrous oxide molecules, as well as of processes of molecular dipole ordering/disordering during cryodeposition from the gas phase.

  10. Towards Trustworthy Adaptive Case Management with Dynamic Condition Response Graphs

    DEFF Research Database (Denmark)

    Mukkamala, Raghava Rao; Hildebrandt, Thomas; Slaats, Tijs

    2013-01-01

    We describe how the declarative Dynamic Condition Response (DCR) Graphs process model can be used for trustworthy adaptive case management by leveraging the flexible execution, dynamic composition and adaptation supported by DCR Graphs. The dynamically composed and adapted graphs are verified...... for deadlock freedom and liveness in the SPIN model checker by utilizing a mapping from DCR Graphs to PROMELA code. We exemplify the approach by a small workflow extracted from a field study at a danish hospital....

  11. From Dynamic Condition Response Structures to Büchi Automata

    DEFF Research Database (Denmark)

    Mukkamala, Raghava Rao; Hildebrandt, Thomas

    2010-01-01

    Recently we have presented distributed dynamic condition response structures (DCR structures) as a declarative process model conservatively generalizing labelled event structures to allow for finite specifications of repeated, possibly infinite behavior. The key ideas are to split the causality r...

  12. Dynamic response of monolithic and laminate/particulate reactive mixtures

    OpenAIRE

    Wei, Chung-Ting

    2011-01-01

    Two dynamic compression methods were applied to a monolithic metal and reactive mixtures to investigate their responses: (a) Dynamic experiments using a split Hopkinson pressure bar were applied to reactive mixtures densified by explosive consolidation in order to establish their mechanical response and failure mechanisms. (b) Laser compression and release, which can impart high stresses, up to hundreds GPa, in times of nanoseconds and fractions thereof, was applied to establish the spalling ...

  13. Measuring the dynamics of neural responses in primary auditory cortex

    CERN Document Server

    Depireux, D A; Shamma, S A; Depireux, Didier A.; Simon, Jonathan Z.; Shamma, Shihab A.

    1998-01-01

    We review recent developments in the measurement of the dynamics of the response properties of auditory cortical neurons to broadband sounds, which is closely related to the perception of timbre. The emphasis is on a method that characterizes the spectro-temporal properties of single neurons to dynamic, broadband sounds, akin to the drifting gratings used in vision. The method treats the spectral and temporal aspects of the response on an equal footing.

  14. WRIST FORCE SENSOR'S DYNAMIC PERFORMANCE CALIBRATION BASED ON NEGATIVE STEP RESPONSE

    Institute of Scientific and Technical Information of China (English)

    ZHENG Hongmei

    2008-01-01

    Negative step response experimental method is used in wrist force sensor's dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor's load in working. This experimental method needn't special experiment equipments. Experiment's dynamic repeatability is good. So wrist force sensor's dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn't require that wavelet primary function be orthogonal and needn't wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor's dynamic characteristics are identified by the frequency response function.

  15. An experimental study on dynamic response for MICP strengthening liquefiable sands

    Science.gov (United States)

    Han, Zhiguang; Cheng, Xiaohui; Ma, Qiang

    2016-12-01

    The technology of bio-grouting is a new technique for soft ground improvement. Many researchers have carried out a large number of experiments and study on this topic. However, few studies have been carried out on the dynamic response of solidified sand samples, such reducing liquefaction in sand. To study this characteristic of microbial-strengthened liquefiable sandy foundation, a microorganism formula and grouting scheme is applied. After grouting, the solidified samples are tested via dynamic triaxial testing to examine the cyclic performance of solidified sand samples. The results indicate that the solidified sand samples with various strengths can be obtained to meet different engineering requirements, the use of bacteria solution and nutritive salt is reduced, and solidified time is shortened to 1-2 days. Most importantly, in the study of the dynamic response, it is found that the MICP grouting scheme is effective in improving liquefiable sand characteristic, such as liquefaction resistance.

  16. Simulation and experimental validation of vehicle dynamic characteristics for displacement-sensitive shock absorber using fluid-flow modelling

    Science.gov (United States)

    Lee, Choon-Tae; Moon, Byung-Young

    2006-02-01

    In this study, a new mathematical dynamic model of shock absorber is proposed to predict the dynamic characteristics of an automotive system. The performance of shock absorber is directly related to the car behaviours and performance, both for handling and ride comfort. Damping characteristics of automotive can be analysed by considering the performance of displacement-sensitive shock absorber (DSSA) for the ride comfort. The proposed model of the DSSA is considered as two modes of damping force (i.e. soft and hard) according to the position of piston. For the simulation validation of vehicle-dynamic characteristics, the DSSA is mathematically modelled by considering the fluid flow in chamber and valve in accordance with the hard, transient and soft zone. And the vehicle dynamic characteristic of the DSSA is analysed using quarter car model. To show the effectiveness of the proposed damper, the analysed results of damping characteristics were compared with the experimental results, which showed similar behaviour with the corresponding experimental one. The simulation results of frequency response are compared with the ones of passive shock absorber. From the simulation results of the DSSA, it can be concluded that the ride comfort of the DSSA increased at the low-amplitude road condition and the driving safety was increased partially at the high-amplitude road condition. The results reported herein will provide a better understanding of the shock absorber. Moreover, it is believed that those properties of the results can be utilised in the dynamic design of the automotive system.

  17. 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.

  18. 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.

  19. Population dynamical responses to climate change

    DEFF Research Database (Denmark)

    Forchhammer, Mads; Schmidt, Niels Martin; Høye, Toke Thomas

    2008-01-01

    it is well established that climatic as well as biological factors, in concert, form the mechanistic basis for our understanding of how populations develop over time and across space. Although this seemingly suggests simplicity, the climate-biology dichotomy of population dynamics embraces...... a bewildering number of interactions. For example, individuals within a population may compete for space and other resources and, being embedded in an ecosystem, individuals in any population may also interact with individuals of competing species as well as those from adjacent trophic levels. In principal...

  20. 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.

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

    Institute of Scientific and Technical Information of China (English)

    Li Lin; Deng Pengcheng; Fan Yu

    2015-01-01

    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 har-monic 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.

  2. Dynamics of Corporate Social Responsibility in Asia

    DEFF Research Database (Denmark)

    Kim, Rebecca Chunghee; Moon, Jeremy

    2015-01-01

    This article investigates Corporate Social Responsibility (CSR) in Asia through two related themes: research knowledge and ethical norms. ‘CSR in Asia’ research is shown to be growing, particularly in East Asia. Compared with Western CSR literature, it is shown to be dominated by empirical...

  3. Dynamic brittle material response based on a continuum damage model

    Energy Technology Data Exchange (ETDEWEB)

    Chen, E.P.

    1994-12-31

    The response of brittle materials to dynamic loads was studied in this investigation based on a continuum damage model. Damage mechanism was selected to be interaction and growth of subscale cracks. Briefly, the cracks are activated by bulk tension and the density of activated cracks are described by a Weibull statistical distribution. The moduli of a cracked solid derived by Budiansky and O`Connell are then used to represent the global material degradation due to subscale cracking. This continuum damage model was originally developed to study rock fragmentation and was modified in the present study to improve on the post-limit structural response. The model was implemented into a transient dynamic explicit finite element code PRONTO 2D and then used for a numerical study involving the sudden stretching of a plate with a centrally located hole. Numerical results characterizing the dynamic responses of the material were presented. The effect of damage on dynamic material behavior was discussed.

  4. Global Dynamic Characteristic of Nonlinear Torsional Vibration System under Harmonically Excitation

    Institute of Scientific and Technical Information of China (English)

    SHI Peiming; LIU Bin; HOU Dongxiao

    2009-01-01

    Torsional vibration generally causes serious instability and damage problems in many rotating machinery parts. The global dynamic characteristic of nonlinear torsional vibration system with nonlinear rigidity and nonlinear friction force is investigated. On the basis of the generalized dissipation Lagrange's equation, the dynamics equation of nonlinear torsional vibration system is deduced. The bifurcation and chaotic motion in the system subjected to an external harmonic excitation is studied by theoretical analysis and numerical simulation. The stability of unperturbed system is analyzed by using the stability theory of equilibrium positions of Hamiltonian systems. The criterion of existence of chaos phenomena under a periodic perturbation is given by means of Melnikov's method. It is shown that the existence of homoclinic and heteroclinic orbits in the unperturbed system implies chaos arising from breaking of homoclinic or heteroclinic orbits under perturbation. The validity of the result is checked numerically. Periodic doubling bifurcation route to chaos, quasi-periodic route to chaos, intermittency route to chaos are found to occur due to the amplitude varying in some range. The evolution of system dynamic responses is demonstrated in detail by Poincare maps and bifurcation diagrams when the system undergoes a sequence of periodic doubling or quasi-periodic bifurcations to chaos. The conclusion can provide reference for deeply researching the dynamic behavior of mechanical drive systems.

  5. Characteristics of seismoelectric interface responses at dipping boundaries

    Science.gov (United States)

    Kröger, B.; Kemna, A.

    2012-04-01

    When crossing an interface between two layers with different petrophysical properties, a seismic wave generates a time-varying charge separation which acts as a dipole radiating electromagnetic energy independently of the seismic wave. If we consider a monochromatic seismic source located above a horizontal interface between such media, the seismic wave traverses the interface and causes relative displacement of ions at the matrix-fluid interface in the pore space. The resulting electric field is due to the streaming current imbalance at the interface. This is equivalent to the case of an electrical dipole oscillating in phase with the seismic wave along such boundary. As a consequence, electromagnetic disturbances are radiated away from the dipole source and can be recorded at various receiver lines. This seismic-to-electromagnetic field conversion at petrophysical boundaries in the 1st Fresnel zone is the so-called seismoelectric interface response. Conceptual field models and theoretical modelling indicate that the interface response should be a multipole electrical source. Higher-order terms will diminish more rapidly with distance and therefore will leave the dipole term to dominate. Thus, a seismoelectric interface response emanating from a horizontal boundary in a homogeneous half-space is expected to exhibit symmetry and amplitude characteristics similar to those of a vertical electric dipole (VED) centred on the interface directly below the shot point. However, no general theoretical predictions concerning the characteristics, the shape and the morphology of the VED induced by seismic waves at dipping interfaces can be found in the literature. To gain insight into the spatio-temporal occurrence and evolution of the seismoelectric interface response for dipping interfaces we run several numerical simulations using different petrophysical parameter set-ups. For the modelling, we make use of a simplified time-domain formulation of the coupled physical problem

  6. DYNAMIC MECHANICAL RESPONSE OF CRAZES IN POLYSTYRENE

    Institute of Scientific and Technical Information of China (English)

    DING Jianfu; XUE Gi; CHENG Rongshi

    1994-01-01

    Dynamic mechanical analysis was used to study the mechanical properties and microstructure of crazes in polystyrene produced in air or in methanol at different temperatures. A new loss peak was found at about 82℃ ,which is assigned to glass transition peak of craze fibrils. The decrease of glass transition temperature of polymer in craze fibrils is due to the high values of surface to volume ratio. The glass transition temperature ratio of craze fibrils to bulk material(Tg'/Tg) has been expressed as a function of the fibrils diameter(d). From Tg'of craze fibrils ,the value of fibril diameter can be calculated. Annealing the crazed specimen at room temperature makes the fibrils plastically deform and cause the fibrils to thin slightly, whereas annealing the crazed specimen at the temperature near Tg of the craze fibrils makes the fibrils bundle together.

  7. Radiation sterilized bone response to dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Mardas, Marcin, E-mail: marcin.mardas@skpp.edu.pl [Department of Oncology, Poznan University of Medical Sciences, ul. Szamarzewskiego 82/84, 60-569 Poznan (Poland); Kubisz, Leszek [Department of Biophysics, Poznan University of Medical Sciences, ul. Fredry 10, 61-701 Poznan (Poland); Biskupski, Piotr; Mielcarek, Slawomir [Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznan (Poland); Stelmach-Mardas, Marta [Department of Bromatology, Poznan University of Medical Sciences, ul. Marcelinska 420, 60-354 Poznan (Poland); Kaluska, Iwona [Centre for Radiation Research and Technology, Institute of Nuclear Chemistry and Technology, ul. Dorodna 16, 03-195 Warsaw (Poland)

    2012-08-01

    Allogeneic bone grafts are used on a large scale in surgeries. To avoid the risk of infectious diseases, allografts should be radiation-sterilized. So far, no international consensus has been achieved regarding the optimal radiation dose. Many authors suggest that bone sterilization deteriorates bone mechanical properties. However, no data on the influence of ionizing radiation on bone dynamic mechanical properties are available. Bovine femurs from 2-year old animal were machine cut and irradiated with the doses 10, 15, 25, 35, 45 and 50 kGy. Dynamic mechanical analysis was performed at 1-10 Hz at the temperature range of 0-350 Degree-Sign C in 3-point bending configuration. No statistically significant differences in storage modulus were observed. However, there were significant decreased values of loss modulus between the samples irradiated with doses of 10 ({down_arrow}14.3%), 15, 45 and 50 kGy ({down_arrow}33.2%) and controls. It was stated that increased irradiation dose decreases the temperature where collagen denaturation process starts and increases the temperature where the collagen denaturation process finishes. It was shown that activation energy of denaturation process is significantly higher for the samples irradiated with the dose of 50 kGy (615 kJ/mol) in comparison with control samples and irradiation with other doses (100-135 kJ/mol). - Highlights: Black-Right-Pointing-Pointer We examine changes in the storage modulus and loss modulus of samples irradiated with doses of 10-50 kGy. Black-Right-Pointing-Pointer We examine changes in the denaturation temperature of samples irradiated with doses of 10-50 kGy. Black-Right-Pointing-Pointer We examine changes in the activation energy of denaturation process of samples irradiated with doses of 10-50 kGy.

  8. Dynamic response of a viscoelastic Timoshenko beam

    Science.gov (United States)

    Kalyanasundaram, S.; Allen, D. H.; Schapery, R. A.

    1987-01-01

    The analysis presented in this study deals with the vibratory response of viscoelastic Timoshenko (1955) beams under the assumption of small material loss tangents. The appropriate method of analysis employed here may be applied to more complex structures. This study compares the damping ratios obtained from the Timoshenko and Euler-Bernoulli theories for a given viscoelastic material system. From this study the effect of shear deformation and rotary inertia on damping ratios can be identified.

  9. Estimating Reduced Consumption for Dynamic Demand Response

    Energy Technology Data Exchange (ETDEWEB)

    Chelmis, Charalampos [Univ. of Southern California, Los Angeles, CA (United States); Aman, Saima [Univ. of Southern California, Los Angeles, CA (United States); Saeed, Muhammad Rizwan [Univ. of Southern California, Los Angeles, CA (United States); Frincu, Marc [Univ. of Southern California, Los Angeles, CA (United States); Prasanna, Viktor K. [Univ. of Southern California, Los Angeles, CA (United States)

    2015-01-30

    Growing demand is straining our existing electricity generation facilities and requires active participation of the utility and the consumers to achieve energy sustainability. One of the most effective and widely used ways to achieve this goal in the smart grid is demand response (DR), whereby consumers reduce their electricity consumption in response to a request sent from the utility whenever it anticipates a peak in demand. To successfully plan and implement demand response, the utility requires reliable estimate of reduced consumption during DR. This also helps in optimal selection of consumers and curtailment strategies during DR. While much work has been done on predicting normal consumption, reduced consumption prediction is an open problem that is under-studied. In this paper, we introduce and formalize the problem of reduced consumption prediction, and discuss the challenges associated with it. We also describe computational methods that use historical DR data as well as pre-DR conditions to make such predictions. Our experiments are conducted in the real-world setting of a university campus microgrid, and our preliminary results set the foundation for more detailed modeling.

  10. The accuracy and response characteristics of a simplified ear oximeter.

    Science.gov (United States)

    Chapman, K R; D'Urzo, A; Rebuck, A S

    1983-06-01

    oximeter (Biox II) were 5.65 seconds and 2.86 seconds in the "normal" and "fast" modes, respectively, by contrast to the 50 percent response time of 2.87 seconds for the other oximeter (H-P 47201A). We conclude that the new oximeter (Biox II) demonstrated accuracy comparable to a more complex and expensive oximeter and had response characteristics that may be useful in clinical and laboratory settings.

  11. Sediment characteristics and transportation dynamics of the Ganga River

    Science.gov (United States)

    Singh, Munendra; Singh, Indra Bir; Müller, German

    2007-04-01

    Understanding of river systems that have experienced various forcing mechanisms such as climate, tectonics, sea level fluctuations and their linkages is a major concern for fluvial scientists. The 2525-km-long Ganga River derives its fluvial flux from northern part of the Indian subcontinent and drops in the Ganga-Brahmaputra delta and the Bengal fan regions. This paper presents a study of the Ganga River sediments for their textural properties, grainsize characteristics, and transportation dynamics. A suite of recently deposited sediments (189 bedload samples and 27 suspended load samples) of the river and its tributaries was collected from 63 locations. Dry and wet sieve methods of grainsize analysis were performed and Folk and Ward's parameters were calculated. Transportation dynamics of the sediment load was assessed by means of channel hydrology, flow/sediment rating curves, bedform mechanics, grainsize images, and cumulative curves. Textural properties of the bedload sediments of the Ganga River tributaries originating from the Himalaya orogenic belt, the northern Indian craton and the Ganga alluvial plain regions are characterised by the predominance of fine to very fine sand, medium to fine sand, and very fine sand to clay, respectively. Downstream textural variations in the bedload and suspended load sediments of the Ganga River are, therefore, complex and are strongly influenced by lateral sediment inputs by the tributaries and channel slope. At the base of the Himalaya, a very sharp gravel-sand transition is present in which median grainsize of bedload sediments decreases from over - 0.16 Φ to 2.46 Φ within a distance of 35 km. Downstream decline in mean grainsize of bedload sediments in the upper Ganga River within the alluvial plain can be expressed by an exponential formula as: mean grainsize (in Φ) = 0.0024 × Distance (in kilometres from the Himalayan front) + 1.29. It is a result of selective transport phenomena rather than of abrasion, the

  12. Effects of Floating Ring Bearing Manufacturing Tolerance Clearances on the Dynamic Characteristics for Turbocharger

    Institute of Scientific and Technical Information of China (English)

    WANG Longkai; BIN Guangfu; LI Xuejun; ZHANG Xuefeng

    2015-01-01

    The inner and outer oil film dynamic characteristic coefficients of floating ring bearings(FRBs) change due to the manufacturing tolerance of the floating ring, journal and intermediate, which leads to high-speed turbocharger’s vibration too large and even causes nonlinear vibration accident. However, the investigation of floating ring bearing manufacturing tolerance clearance on the rotordynamic characteristics is less at present. In order to study the influence law of inner and outer clearance on turbocharger vibration, the rotor dynamic motion equations of turbocharger supported in FRBs are derived by analyzing the size relations between floating ring, journal and intermediate for the inner and outer oil film clearances, the time transient response analysis for combination of FRBs clearance are developed. A realistic turbocharger is taken as a research object, the FE model of the turbocharger with FRBs is modeled. Under the conditions of four kinds of limit state bearing clearances for inner and outer oil film, the nonlinear transient analyses are performed based on the established FE dynamic models of the nonlinear rotor-FRBs system applied incentive combinations of gravity and unbalance force, respectively. From the waterfall, the simulation results show that the speed for the appearance of fractional frequency is not identical and the amplitude magnitude is different under the four kinds of bearing manufacturing tolerance limit clearances, and fractional frequency does not appear in the turbocharger and the amplitude is minimum under the ODMin/IDMax bearing manufacturing tolerance clearances. The turbocharger vibration is reduced by controlling the manufacturing tolerance clearance combinations of FRBs, which is helpful for the dynamic design and production-manufacturing of high-speed turbocharger.

  13. 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

    our observation of 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. PMID:27014016

  14. 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.

  15. 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

  16. Cooperative dynamics in auditory brain response

    CERN Document Server

    Kwapien, J; Liu, L C; Ioannides, A A

    1998-01-01

    Simultaneous estimates of the activity in the left and right auditory cortex of five normal human subjects were extracted from Multichannel Magnetoencephalography recordings. Left, right and binaural stimulation were used, in separate runs, for each subject. The resulting time-series of left and right auditory cortex activity were analysed using the concept of mutual information. The analysis constitutes an objective method to address the nature of inter-hemispheric correlations in response to auditory stimulations. The results provide a clear evidence for the occurrence of such correlations mediated by a direct information transport, with clear laterality effects: as a rule, the contralateral hemisphere leads by 10-20ms, as can be seen in the average signal. The strength of the inter-hemispheric coupling, which cannot be extracted from the average data, is found to be highly variable from subject to subject, but remarkably stable for each subject.

  17. Monitoring the intracellular calcium response to a dynamic hypertonic environment

    Science.gov (United States)

    Huang, Xiaowen; Yue, Wanqing; Liu, Dandan; Yue, Jianbo; Li, Jiaqian; Sun, Dong; Yang, Mengsu; Wang, Zuankai

    2016-03-01

    The profiling of physiological response of cells to external stimuli at the single cell level is of importance. Traditional approaches to study cell responses are often limited by ensemble measurement, which is challenging to reveal the complex single cell behaviors under a dynamic environment. Here we report the development of a simple microfluidic device to investigate intracellular calcium response to dynamic hypertonic conditions at the single cell level in real-time. Interestingly, a dramatic elevation in the intracellular calcium signaling is found in both suspension cells (human leukemic cell line, HL-60) and adherent cells (lung cancer cell line, A549), which is ascribed to the exposure of cells to the hydrodynamic stress. We also demonstrate that the calcium response exhibits distinct single cell heterogeneity as well as cell-type-dependent responses to the same stimuli. Our study opens up a new tool for tracking cellular activity at the single cell level in real time for high throughput drug screening.

  18. The response characteristics of tetrazolium violet solutions to gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Emi-Reynolds, G. [Radiation Protection Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon-Accra (Ghana)]. E-mail: gemi-reynolds@idngh.com; Kovacs, Andras [Institute of Isotopes, Hungarian Academy of Sciences, P.O. Box 77, Budapest H-1525 (Hungary); Fletcher, J.J. [Department of Physics, University of Cape Coast, Cape Coast (Ghana)

    2007-08-15

    The dosimetry characteristics of various solutions of tetrazolium violet, TV, (2,5-diphenyl-3-(1-naphthyl)-2H-tetrazolium chloride) to gamma irradiation are reported. The optical absorption spectra of these solutions show peaks between 400 and 600 nm with a shoulder at around 550 nm. The dose response of the optical absorbance values of aqueous and aqueous-alcoholic solutions containing different concentrations of TV was measured in the 250 Gy up to 75 kGy dose range. The formation of formazan product was observed due to radiolytic reduction in both solutions. Its formation was found more pronounced in N{sub 2}-saturated as well as in alkaline solutions. The results indicate that the 1 mM TV solution can be used for food irradiation and medical sterilization dosimetry at gamma irradiation facilities.

  19. The response characteristics of tetrazolium violet solutions to gamma irradiation

    Science.gov (United States)

    Emi-Reynolds, G.; Kovács, András; Fletcher, J. J.

    2007-08-01

    The dosimetry characteristics of various solutions of tetrazolium violet, TV, (2,5-diphenyl-3-(1-naphthyl)-2H-tetrazolium chloride) to gamma irradiation are reported. The optical absorption spectra of these solutions show peaks between 400 and 600 nm with a shoulder at around 550 nm. The dose response of the optical absorbance values of aqueous and aqueous-alcoholic solutions containing different concentrations of TV was measured in the 250 Gy up to 75 kGy dose range. The formation of formazan product was observed due to radiolytic reduction in both solutions. Its formation was found more pronounced in N 2-saturated as well as in alkaline solutions. The results indicate that the 1 mM TV solution can be used for food irradiation and medical sterilization dosimetry at gamma irradiation facilities.

  20. Dynamic modelling of an electromechanical valve using frequency response data

    OpenAIRE

    Miller, R L; Smith, D. L.

    1986-01-01

    Dynamic modelling of electromechanical parts is often accomplished by conducting an analysis from first physical principles. While this is always a useful effort for physical insight, it may lead to transfer function models which are unnecessarily complex. This paper presents a supplementary dynamic modelling method based on frequency response data. The method is applied to modelling of a globe valve use for water flow control Naval Postgraduate School, Monterey, CA. http://archive.org/...

  1. Roadway dynamic response analysis under mining rockburst condition

    Institute of Scientific and Technical Information of China (English)

    LI Chun-rui; QI Qing-xin; PAN Jun-feng; LAN Hang

    2009-01-01

    In order to determine how a roadway withstands a momentum wave and de-termine the extent of damage to rock surrounding the roadway under different force wave peak impacts, the roadway dynamic response state was analysed using numerical simula-tion method. The roadway's critical peak force wave and fracture region under dynamic wave action were put forward. It is concluded that the method has practical value to road-way support and rockburst prevention.

  2. 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.

  3. Investigation of dynamic characteristics of a rotor system with surface coatings

    Science.gov (United States)

    Yang, Yang; Cao, Dengqing; Wang, Deyou

    2017-02-01

    A Jeffcott rotor system with surface coatings capable of describing the mechanical vibration resulting from unbalance and rub-impact is formulated in this article. A contact force model proposed recently to describe the impact force between the disc and casing with coatings is employed to do the dynamic analysis for the rotor system with rubbing fault. Due to the variation of penetration, the contact force model is correspondingly modified. Meanwhile, the Coulomb friction model is applied to simulate the friction characteristics. Then, the case study of rub-impact with surface coatings is simulated by the Runge-Kutta method, in which a linear interpolation method is adopted to predict the rubbing instant. Moreover, the dynamic characteristics of the rotor system with surface coatings are analyzed in terms of bifurcation plot, waveform, whirl orbit, Poincaré map and spectrum plot. And the effects of the hardness of surface coatings on the response are investigated as well. Finally, compared with the classical models, the modified contact force model is shown to be more suitable to solve the rub-impact of aero-engine with surface coatings.

  4. Dynamic characteristics and sensitivities analysis of a power turret gear train

    Institute of Scientific and Technical Information of China (English)

    Xu Lijiao; Chen Nan

    2014-01-01

    The dynamic transmission characteristics and the sensitivities of the three stage idler gear system of the new NC power turret are studied in the paper. Considering the strongly nonlinear factors such as the periodically time-varying mesh stiffness, the nonlinear tooth backlash, the lump-parameter model of the gear system is developed with one rotational and two translational freedoms of each gear. The eigen-values and eigenvectors are derived and analyzed on the basis of the real modal theory. The sensitivities of natural frequencies to design parameters including supporting and meshing stiffnesses, gear masses, and moments of inertia by the direct differential method are also calculated. The results show the quantitative and qualitative impact of the parameters to the natural characteristics of the gear system. Furthermore, the periodic steady state solutions are obtained by the numerical approach based on the nonlinear model. These results are employed to gain insights into the primary controlling parameters, to forecast the severity of the dynamic response, and to assess the acceptability of the gear design.

  5. DYNAMIC CHARACTERISTICS OF SOILS SUBJECT TO IMPACT LOADINGS

    Institute of Scientific and Technical Information of China (English)

    Zhirong Niu; Guoyun Lu; Dongzuo Cheng

    2008-01-01

    The dynamic properties of soil under impact loads are studied experimentally and numerically.By analyzing the microstructural photos of soils with and without impact,it is shown that impact loads can destroy the original structures in the compact area,where the soil grains are rearranged regularly and form the compact whirlpool structure.Simultaneously,the dynamic impact process of soil is simulated by using the software of Ls-dyna.The time-dependent distribution of the dynamic stress and density is obtained in the soil.Furthermore,the simulation results are consistent with the experimental results.The reinforcement mechanism and the rule of dynamic compaction of soils due to impact load are also elucidated.

  6. Capturing the dynamic nascent transcriptome during acute cellular responses: The serum response

    Directory of Open Access Journals (Sweden)

    Killeen S. Kirkconnell

    2016-06-01

    Full Text Available Dynamic regulation of gene expression via signal transduction pathways is of fundamental importance during many biological processes such as cell state transitioning, cell cycle progression and stress responses. In this study we used serum stimulation as a cell response paradigm to apply the nascent RNA Bru-seq technique in order to capture early dynamic changes in the nascent transcriptome. Our data provides an unprecedented view of the dynamics of genome-wide transcription during the first two hours of serum stimulation in human fibroblasts. While some genes showed sustained induction or repression, other genes showed transient or delayed responses. Surprisingly, the dynamic patterns of induction and suppression of response genes showed a high degree of similarity, suggesting that these opposite outcomes are triggered by a common set of signals. As expected, early response genes such as those encoding components of the AP-1 transcription factor and those involved in the circadian clock were immediately but transiently induced. Surprisingly, transcription of important DNA damage response genes and histone genes were rapidly repressed. We also show that RNA polymerase II accelerates as it transcribes large genes and this was independent of whether the gene was induced or not. These results provide a unique genome-wide depiction of dynamic patterns of transcription of serum response genes and demonstrate the utility of Bru-seq to comprehensively capture rapid and dynamic changes of the nascent transcriptome.

  7. Dynamic response of a poroelastic stratum to moving oscillating load

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The dynamic response of a poroelastic stratum subjected to moving load is studied. The governing dynamic equations for poroelastic medium are solved by using Fourier transform. The general solutions for the stresses and displacements in the transformed domain are established. Based on the general solutions, with the consideration of boundary conditions, the final expressions of stresses and displacements in physical domain are put forward for the three-dimensional single-layer medium. Some numerical solutions for the stresses, displacements and pore fluid pressure are presented and reveal that the response of a poroelastic stratum varies obviously with the moving velocity.

  8. Development of study on the dynamic characteristics of deep water mooring system

    Institute of Scientific and Technical Information of China (English)

    TANG You-gang; ZHANG Su-xia; ZHANG Ruo-yu; LIU Hai-xiao

    2007-01-01

    To meet the needs of those exploiting deepwater resources, TLP and SPAR platforms are used in some areas and are considered excellent platforms in deep water. However, many problems remain to be resolved. The design of mooring systems is a key issue for deep water platforms. Environmental loads in deep water effect the physical characteristics of mooring line materials. The configuration and analysis of mooting systems involve nonlinearity due to this fluid-solid coupling, nonlinear hydrodynamic forces, and their effects on stability of motion. In this paper, some pivotal theories and technical questions are presented, including modeling of mooring lines, the theory and method of coupled dynamics analysis on the mooring system, and the development of methodologies for the study of nonlinear dynamics of mooring systems. Further study on mooring systems in deep water are recommended based on current knowledge, particularly dynamic parameters of different materials and cable configuration, interactions between seabed and cable, mechanisms of mooring system response induced by taut/slack mooring cables, discontinuous stiffness due to system materials, mooting construction, and motion instability, etc.

  9. Dynamic characteristics of nanoindentation in Ni:A molecular dynamics simulation study

    Institute of Scientific and Technical Information of China (English)

    Muhammad Imran; Fayyaz Hussain; Muhammad Rashid; S.A.Ahmad

    2012-01-01

    In this work,three-dimensional molecular dynamics simulation is carried out to elucidate the nanoindentation behaviour of single crystal Ni.The substrate indenter system is modelled using hybrid interatomic potentials including the manybody potential (embedded atom method) and two-body Morse potential.The spherical indenter is chosen,and the simulation is performed for different loading rates from 10 m/s to 200 m/s.Results show that the maximum indentation load and hardness of the system increase with the increase of velocity.The effect of indenter size on the nanoindentation response is also analysed.It is found that the maximum indentation load is higher for the large indenter whereas the hardness is higher for the smaller indenter.Dynamic nanoindentation is carried out to investigate the behaviour of Ni substrate to multiple loading-unloading cycles.It is observed from the results that the increase in the number of loading unloading cycles reduces the maximum load and hardness of the Ni substrate.This is attributed to the decrease in recovery force due to defects and dislocations produced after each indentation cycle.

  10. Dynamic modeling of cellular response to DNA damage based on p53 stress response networks

    Institute of Scientific and Technical Information of China (English)

    Jinpeng Qi; Yongsheng Ding; Shihuang Shao

    2009-01-01

    Under acute perturbations from the outside, cells can trigger self-defensive mechanisms to fight against genome stress. To investigate the cellular response to continuous ion radiation (IR), a dynamic model for p53 stress response networks at the cellular level is proposed. The model can successfully be used to simulate the dynamic processes of double-strand breaks (DSBs) generation and their repair, switch-like ataxia telangiectasia mutated (ATM) activation, oscillations occurring in the p53-MDM2 feedback loop, as well as toxins elimination triggered by p53 stress response networks. Especially, the model can predict the plausible outcomes of cellular response under different IR dose regimes.

  11. Study on Dynamic Response Measurement of the Submarine Pipeline by Full-Term FBG Sensors

    Directory of Open Access Journals (Sweden)

    Jinghai Zhou

    2014-01-01

    Full Text Available The field of structural health monitoring is concerned with accurately and reliably assessing the integrity of a given structure to reduce ownership costs, increase operational lifetime, and improve safety. In structural health monitoring systems, fiber Bragg grating (FBG is a promising measurement technology for its superior ability of explosion proof, immunity to electromagnetic interference, and high accuracy. This paper is a study on the dynamic characteristics of fiber Bragg grating (FBG sensors applied to a submarine pipeline, as well as an experimental investigation on a laboratory model of the pipeline. The dynamic response of a submarine pipeline under seismic excitation is a coupled vibration of liquid and solid interaction. FBG sensors and strain gauges are used to monitor the dynamic response of a submarine pipeline model under a variety of dynamic loading conditions and the maximum working frequency of an FBG strain sensor is calculated according to its dynamic strain responses. Based on the theoretical and experimental results, it can be concluded that FBG sensor is superior to strain gauge and satisfies the demand of dynamic strain measurement.

  12. Analysis of Dynamic Response of Tramway on Tracks with Varying Level of Maintenance

    Directory of Open Access Journals (Sweden)

    Kominowski Julian

    2016-10-01

    Full Text Available The paper presents feature of geometric track irregularities occurring on tram infrastructure with varying levels of maintenance and their influence on vehicle’s dynamic response. Measurements of vehicle’s model masses accelerations were conducted during rides on chosen track sections projecting real geometry. Frequency characteristics of vibration accelerations obtained from simulation and spectra of measured track irregularities were shown and compared to find the relationship between them.

  13. Dynamic responses under the excitation of pulse sequences

    Institute of Scientific and Technical Information of China (English)

    Dai Junwu(戴君武); Mai Tong; George C. Lee; Qi Xiaozhai(齐霄斋); Bai Wenting(白文婷)

    2004-01-01

    This paper studies the dynamic responses of SDOF system under pulse-dominant excitations. The purpose of the study is to prepare for scrutiny of some near-field pulse-dominant ground motions and their potential to cause structural damage. Extending the single pulse dynamics, we consider the effect of pulse sequences. This kind of excitation was particularly obvious in some of previous earthquakes such as Northridge (1994) and Chi-Chi (1995). Based on the duration,peak and rise and decay era of the main pulse as well as its relationship with the predecessor and successor pulses, we propose a classification for the pulse sequences. Consequent studies have been carried out for acceleration, velocity and displacement response spectra of the main pulse with either a predecessor or a successor pulse. The analysis also includes general response behaviors in different fundamental period segments and special aspects of response at certain points (e.g., the corresponding peak points).

  14. 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.

  15. Dynamic Response of Parallel Hoisting System under Drive Deviation between Ropes with Time-Varying Length

    Directory of Open Access Journals (Sweden)

    Guohua Cao

    2017-01-01

    Full Text Available The dynamic responses of parallel hoisting system with time-varying length and rigid guidance under drive deviation are investigated considering tension and torsion characteristics of the ropes. The variable-domain three-node elements of rope are employed and the corresponding differential algebraic equations (DAEs are derived using Lagrange’s equations of the first kind. The slack situation of the rope is considered, and the dynamic equations which are systems of DAEs are transformed to ordinary differential equations (ODEs. The dynamic responses of tension, torsion, and acceleration are analyzed considering radius’ error of the drums, which indicates that the drive deviation between ropes can cause large influence on the tension difference and even cause one of the ropes to slack. However, the torsion of the corresponding rope is active. And unreasonable discordance between ropes should be controlled for the design and manufacture of drum on super deep parallel hoisting system.

  16. Dynamic Characteristics of a Model and Prototype for 3D-RC Structure

    Directory of Open Access Journals (Sweden)

    Moniuddin Md. Khaja

    2016-06-01

    Full Text Available Infill walls provide durable and economical partitions that have relatively excellent thermal and sound insulation with high fire resistance. Monolithic infilled walls are provided within RC structures without being analyzed as a combination of concrete and brick elements, although in reality they act as a single unit during earthquakes. The performance of such structures during earthquakes has proved to be superior in comparison to bare frames in terms of stiffness, strength and energy dissipation. To know the dynamic characteristics of monolithic infill wall panels and masonry infill, modal, response spectrum and time history analyses have been carried out on a model and prototype of a 3D RC structure for a comparative study.

  17. Nonlinear Dynamic Characteristics and Optimal Control of SMA Composite Wings Subjected to Stochastic Excitation

    Directory of Open Access Journals (Sweden)

    Zhi-Wen Zhu

    2015-01-01

    Full Text Available A kind of high-aspect-ratio shape memory alloy (SMA composite wing is proposed to reduce the wing’s fluttering. The nonlinear dynamic characteristics and optimal control of the SMA composite wings subjected to in-plane stochastic excitation are investigated where the great bending under the flight loads is considered. The stochastic stability of the system is analyzed, and the system’s response is obtained. The conditions of stochastic Hopf bifurcation are determined, and the probability density of the first-passage time is obtained. Finally, the optimal control strategy is proposed. Numerical simulation shows that the stability of the system varies with bifurcation parameters, and stochastic Hopf bifurcation appears in the process; the reliability of the system is improved through optimal control, and the first-passage time is delayed. Finally, the effects of the control strategy are proved by experiments. The results of this paper are helpful for engineering applications of SMA.

  18. VIBRATION RESPONSE AND ITS CHARACTERISTICS OF CENTRIFUGAL COMPRESSOR WITH ROTATING STALL

    Institute of Scientific and Technical Information of China (English)

    Yan Xianguo; Guan Huiling; Zhang Youyun

    2004-01-01

    Based on the beginning, propagating and ending mechanism of rotating-stall cell, the relation between the pressure history signal and the pressure distribution along rotor circumference is proposed.The angular velocities of rotating-stall cell propagating are computed from time series picked by the pressure probes on a cross section.Self-relation calculating filtered the random noise of the pressure history data.The exciting load on rotor is computed by integral of filtered pressure signal along rotor circumference.By Prohl-Myklestad method, dynamical equations of rotor system are obtained.The dynamical response of rotor system is resolved by using Matlab system.Further more, the situation of more than one of stall cells is discussed.Two cases respectively from the natural gas compressor of some fertilizer plant and the CO2 compressor of some nitrogenous fertilizer plant demonstrate that both methods of calculating the load exerted on rotor by pressure fluctuation and resolving the dynamic response of rotor are available and the characteristics of frequency spectrum of rotating stall are correct.

  19. Dynamic modelling of pectin extraction describing yield and functional characteristics

    DEFF Research Database (Denmark)

    Andersen, Nina Marianne; Cognet, T.; Santacoloma, P. A.

    2017-01-01

    A dynamic model of pectin extraction is proposed that describes pectin yield, degree of esterification and intrinsic viscosity. The dynamic model is one dimensional in the peel geometry and includes mass transport of pectin by diffusion and reaction kinetics of hydrolysis, degradation and de-esterification....... The model takes into account the effects of the process conditions such as temperature and acid concentration on extraction kinetics. It is shown that the model describes pectin bulk solution concentration, degree of esterification and intrinsic viscosity in pilot scale extractions from lime peel...

  20. Estimating the ride quality characteristics of vehicles with random decrement analysis of on-the-road vibration response data

    Science.gov (United States)

    Ainalis, Daniel; Rouillard, Vincent; Sek, Michael

    2016-06-01

    This paper describes the application of a practical analytical technique based on the random decrement method to estimate the rigid sprung mass dynamic characteristics (frequency response function) of road vehicles using only vibration response data during constant-speed operation. A brief history and development of the random decrement technique is presented, along with a summary of work undertaken on optimal parameter selection to establish the random decrement signature. Two approaches to estimate the dynamic characteristics from the random decrement signature are described and evaluated. A custom, single-wheeled vehicle (physical quarter car) was commissioned to undertake a series of on-the-road experiments at various nominally constant operating speeds. The vehicle, also instrumented as an inertial profilometer, simultaneously measured the longitudinal pavement profile to establish the vehicle's actual dynamic characteristics during operation. The main outcome of the paper is that the random decrement technique can be used to provide accurate estimates of the sprung mass mode of the vehicle's dynamic characteristics for both linear and nonlinear suspension systems of an idealised vehicle.

  1. Spatial Finite Element Analysis for Dynamic Response of Curved Thin-Walled Box Girder Bridges

    Directory of Open Access Journals (Sweden)

    Yinhui Wang

    2016-01-01

    Full Text Available According to the flexural and torsional characteristics of curved thin-walled box girder with the effect of initial curvature, 7 basic displacements of curved box girder are determined. And then the strain-displacement calculation correlations were established. Under the curvilinear coordinate system, a three-noded curved girder finite element which has 7 degrees of freedom per node for the vibration characteristic and dynamic response analysis of curved box girder is constructed. The shape functions are used as the interpolation functions of variable curvature and variable height to accommodate to the variation of curvature and section height. A MATLAB numerical analysis program has been implemented.

  2. Finite Element Vibration and Dynamic Response Analysis of Engineering Structures

    Directory of Open Access Journals (Sweden)

    Jaroslav Mackerle

    2000-01-01

    Full Text Available This bibliography lists references to papers, conference proceedings, and theses/dissertations dealing with finite element vibration and dynamic response analysis of engineering structures that were published from 1994 to 1998. It contains 539 citations. The following types of structures are included: basic structural systems; ground structures; ocean and coastal structures; mobile structures; and containment structures.

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

    NARCIS (Netherlands)

    Ranade, V.V.; Kuipers, J.A.M.; Versteeg, G.F.

    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. Mathematical modeling of the aerodynamic characteristics in flight dynamics

    Science.gov (United States)

    Tobak, M.; Chapman, G. T.; Schiff, L. B.

    1984-01-01

    Basic concepts involved in the mathematical modeling of the aerodynamic response of an aircraft to arbitrary maneuvers are reviewed. The original formulation of an aerodynamic response in terms of nonlinear functionals is shown to be compatible with a derivation based on the use of nonlinear functional expansions. Extensions of the analysis through its natural connection with ideas from bifurcation theory are indicated.

  5. Dynamic Characteristic Analysis and Experiment for Integral Impeller Based on Cyclic Symmetry Analysis Method

    Institute of Scientific and Technical Information of China (English)

    WU Qiong; ZHANG Yidu; ZHANG Hongwei

    2012-01-01

    A cyclic symmetry analysis method is proposed for analyzing the dynamic characteristic problems of thin walled integral impeller.Reliability and feasibility of the present method are investigated by means of simulation and experiment.The fundamental cyclic symmetry equations and the solutions of these equations are derived for the cyclic symmetry structure.The computational efficiency analysis between whole and part is performed.Comparison of results obtained by the finite element analysis (FEA)and experiment shows that the local dynamic characteristic of integral impeller has consistency with the single cyclic symmetry blade.When the integral impeller is constrained and the thin walled blade becomes a concerned object in analysis,the dynamic characteristic of integral impeller can be replaced by the cyclic symmetry blade approximately.Hence,a cyclic symmetry analysis method is effectively used to improve efficiency and obtain more information of parameters for dynamic characteristic of integral impellers.

  6. Responsiveness of muscle tone characteristics to progressive force production.

    Science.gov (United States)

    Mustalampi, Sirpa; Häkkinen, Arja; Kautiainen, Hannu; Weir, Adam; Ylinen, Jari

    2013-01-01

    It is possible to measure muscle tone reliably, quickly and objectively using tonometers although they are not yet widely used. In clinical practice, it may be helpful if clinicians could assess the degree of contraction in different parts of a muscle without having to perform time-consuming electromyography measurements. The purpose of this study was to evaluate the responsiveness of different muscle tone characteristics to progressively increased contraction force of quadriceps muscle. Twenty healthy subjects (mean age 39.9 years, 50% women) volunteered. Using 2 different tonometers various muscle viscoelastic properties were measured. The frequency (hertz), logarithmic decrement, and stiffness (newtons per meter) of damped mechanical oscillation of the muscle tissue and tissue compliance (millijoules) were registered from rectus femoris muscle at rest and 20, 40, 60, 80% of maximal voluntary contraction determined using dynamometry. All the values changed linearly with increasing force level. Compliance, oscillation stiffness, and frequency parameters showed large effect sizes (ESs ≥ 0.8). The standardized respoknse mean for compliance was 5.3 (4.8-5.7) mJ, for oscillation stiffness 1.8 (1.3-2.2) N·m(-1), frequency 1.1 (0.6-1.5) Hz, and decrement -0.6 (-1.0 to -0.2). The results indicate that the compliance and oscillation stiffness parameters showed the highest responsiveness and can thus best detect changes in muscle contraction state. The additional value of using tonometers to measure these properties in clinical practice should be investigated further.

  7. Stochastic modeling of uncertain mass characteristics in rigid body dynamics

    Science.gov (United States)

    Richter, Lanae A.; Mignolet, Marc P.

    2017-03-01

    This paper focuses on the formulation, assessment, and application of a modeling strategy of uncertainty on the mass characteristics of rigid bodies, i.e. mass, position of center of mass, and inertia tensor. These characteristics are regrouped into a 4×4 matrix the elements of which are represented as random variables with joint probability density function derived following the maximum entropy framework. This stochastic model is first shown to satisfy all properties expected of the mass and tensor of inertia of rigid bodies. Its usefulness and computational efficiency are next demonstrated on the behavior of a rigid body in pure rotation exhibiting significant uncertainty in mass distribution.

  8. Study on the dynamic response analysis for evaluating the effectiveness of base isolation for nuclear components

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Kazunari; Tsutsumi, Hideaki; Yamada, Hiroyuki; Ebisawa, Katsumi; Shibata, Katsuyuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-07-01

    Introduction of the base isolation technique into the seismic design of nuclear power plant components as well as buildings has been expected as one of the effective countermeasure to reduce the seismic force applied to components. A research program on the base isolation of nuclear components has been carried out at the Japan Atomic Energy Research Institute (JAERI) since 1991. A methodology and a computer code (EBISA: Equipment Base Insolation System Analysis) for evaluating the failure frequency of the nuclear component with the base isolation were developed. In addition, a test program, which is concerned with the above development, aiming at improvement of failure frequency analysis models in the code has been conducted since 1996 to investigate the dynamic behavior and to verify the effectiveness of component base isolation systems. In the failure frequency analysis, methodology for evaluating the actual dynamic responses of the nuclear components with the base isolation in detail has been examined. In the methodology, the actual responses are computed by considering the scatter in mechanical properties of rock masses, reactor building and components under many earthquake motions with various frequency characteristics. The failure frequency of component is computed as the conditional probability where the actual response exceeds the capacity of components. It is a very important in the above methodology to investigates the dynamic response analysis method for the ground, reactor building and nuclear components as well as the scattering factors in the dynamic analysis. This report describes the accuracy of the dynamic response analysis method and analysis models, and the influence of scatters in properties of rock masses and reactor building on the dynamic response. (author)

  9. Dynamic Characteristics Analysis of the Coupled Lateral-Torsional Vibration with Spur Gear System

    OpenAIRE

    Shihua Zhou; Zhaohui Ren; Guiqiu Song; Bangchun Wen

    2015-01-01

    A sixteen-degree-of-freedom (16-DOF) lumped parameter dynamic model taking into account the gravity, eccentricity, bearing clearance, transmission error, and coupled lateral-torsional vibration is established. Based on the dynamical equation, the dynamic behaviors of the spur gear rotor bearing system are investigated by using Runge-Kutta method. The research focuses on the effect of rotational speed, eccentricity, and bearing clearance and nonlinear response of the coupled multibody dynamics...

  10. Nonlinear dynamic analysis and characteristics diagnosis of seasonally perturbed predator-prey systems

    Science.gov (United States)

    Zhang, Huayong; Huang, Tousheng; Dai, Liming

    2015-05-01

    Predator-prey interaction widely exists in nature and the research on predator-prey systems is an important field in ecology. The nonlinear dynamic characteristics of a seasonally perturbed predator-prey system are studied in this research. To study the nonlinear characteristics affected by a wide variety of system parameters, the PR approach is employed and periodic, quasiperiodic, chaotic behaviors and the behaviors between period and quasiperiod are found in the system. Periodic-quasiperiodic-chaotic region diagrams are generated for analyzing the global characteristics of the predator-prey system with desired ranges of system parameters. The ecological significances of the dynamical characteristics are discussed and compared with the theoretical research results existing in the literature. The approach of this research demonstrates effectiveness and efficiency of PR method in analyzing the complex dynamical characteristics of nonlinear ecological systems.

  11. Thermoviscoelastic dynamic response for a composite material thin narrow strip

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Hong Liang; Qi, Li-Li; Liu, Hai-Bo [Hunan University, Changsha (China)

    2015-02-15

    Based on von Karman nonlinear strain-displacement relationships and classical thin plate theory, a list of nonlinear dynamic equilibrium equations for a viscoelastic composite material thin narrow strip under thermal and mechanic loads are deduced. According to the material constitutive relationship and the relaxation modulus in the form of the Prony series, combing with the Newmark method and the Newton-cotes integration method, a new numerical algorithm for direct solving the whole problem in the time domain is established. By applying this numerical algorithm, the viscoelastic composite material thin narrow strip as the research subject is analyzed systematically, and its rich dynamical behaviors are revealed comprehensively. To verify the accuracy of the present work, a comparison is made with previously published results. Finally, the viscoelastic composite material thin narrow strip under harmonic excitation load and impact load are discussed in detail, and many valuable thermoviscoelastic dynamic characteristics are revealed.

  12. Transcriptome dynamics of the microRNA inhibition response

    DEFF Research Database (Denmark)

    Wen, Jiayu; Leucci, Elenora; Vendramin, Roberto

    2015-01-01

    We report a high-resolution time series study of transcriptome dynamics following antimiR-mediated inhibition of miR-9 in a Hodgkin lymphoma cell-line-the first such dynamic study of the microRNA inhibition response-revealing both general and specific aspects of the physiological response. We show...... validate the key observations with independent time series qPCR and we experimentally validate key predicted miR-9 targets. Methodologically, we developed sensitive functional data analytic predictive methods to analyse the weak response inherent in microRNA inhibition experiments. The methods...... of this study will be applicable to similar high-resolution time series transcriptome analyses and provides the context for more accurate experimental design and interpretation of future microRNA inhibition studies....

  13. Analysis of bacterial chemotactic response using dynamic laser speckle

    Science.gov (United States)

    Murialdo, Silvia E.; Sendra, Gonzalo H.; Passoni, Lucía I.; Arizaga, Ricardo; Gonzalez, J. Froilán; Rabal, Héctor; Trivi, Marcelo

    2009-11-01

    Chemotaxis has a meaningful role in several fields, such as microbial physiology, medicine and biotechnology. We present a new application of dynamic laser speckle (or biospeckle) to detect different degrees of bacterial motility during chemotactic response experiments. Encouraging results showed different bacterial dynamic responses due to differences in the hardness of the support in the swarming plates. We compare this method to a conventional technique that uses white light. Both methods showed to be analogous and, in some cases, complementary. The results suggest that biospeckle processed images can be used as an alternative method to evaluate bacterial chemotactic response and can supply additional information about the bacterial motility in different areas of the swarm plate assay that might be useful for biological analysis.

  14. 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.

  15. 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.

  16. Experiment and Formulations for the Dynamic Characteristics of Jointed Structures

    Directory of Open Access Journals (Sweden)

    Rongqiang Liu

    2013-01-01

    Full Text Available Clearance joints significantly affect the dynamic properties of deployable structures (DSs. This paper presents a spring-mass model with clearance for the study of the axial stiffness of a jointed structure. The nonlinear stiffness can be predicted by calculating the model's natural frequency which is the reciprocal of the motion period of the model. The results of the theoretical model show that the dynamic stiffness of the clearance joint increases with increases in the displacement amplitude; this finding is consistent with the experimental results. With the inclusion of sliding factors, contact friction, and impact, the established model of energy dissipation is useful for estimating the effects of joint damping on DSs. The energy dissipation model reveals the effects of joint features and excitation conditions on the dissipation of the jointed structure, that is, the excitation frequency and amplitude. Dynamic experiments were performed on jointed structures to characterize the dissipation variations. An exponentially fitting equation was developed based on the energy dissipation model and was verified through the experimental data. This formulation is more efficient than numerical integration for the calculation of the energy dissipation.

  17. Loudness Change in Response to Dynamic Acoustic Intensity

    Science.gov (United States)

    Olsen, Kirk N.; Stevens, Catherine J.; Tardieu, Julien

    2010-01-01

    Three experiments investigate psychological, methodological, and domain-specific characteristics of loudness change in response to sounds that continuously increase in intensity (up-ramps), relative to sounds that decrease (down-ramps). Timbre (vowel, violin), layer (monotone, chord), and duration (1.8 s, 3.6 s) were manipulated in Experiment 1.…

  18. A Study on Dynamic Response of Cable-Seabed Interaction

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; HUANG Guo-liang; DENG De-heng; TU Xing-hua

    2009-01-01

    A numerical method is developed to investigate the dynamic response of cable-seabed interaction in this paper. The motion of cable is described by the Lumped Parameter Method, while the seabed, unlike the prevailing simplified model of elastic foundation, is modeled as an irregular continuous rigid surface with rebound and friction existing, and the forces exerted by the seabed consist of normal counterforce and isotropic tangential Coulomb friction resistance. To describe the detailed dynamic response, two coefficients are introduced by analogy with the theory of rigid body collision with friction. The cable-seabed kinematic and dynamic contact conditions are formulated subsequently, and are used to incorporate the seabed effect into the cable dynamics to produce a set of ordinary differential governing equations. In this paper, we employ 4th order Runge-Kutta method to solve these equations. Several simulation cases are presented to illustrate the seabed effect. The results show that friction and impact have a prominent influence on the statics and dynamics of the cable.

  19. Dynamic resource allocation in disaster response: tradeoffs in wildfire suppression.

    Directory of Open Access Journals (Sweden)

    Nada Petrovic

    Full Text Available Challenges associated with the allocation of limited resources to mitigate the impact of natural disasters inspire fundamentally new theoretical questions for dynamic decision making in coupled human and natural systems. Wildfires are one of several types of disaster phenomena, including oil spills and disease epidemics, where (1 the disaster evolves on the same timescale as the response effort, and (2 delays in response can lead to increased disaster severity and thus greater demand for resources. We introduce a minimal stochastic process to represent wildfire progression that nonetheless accurately captures the heavy tailed statistical distribution of fire sizes observed in nature. We then couple this model for fire spread to a series of response models that isolate fundamental tradeoffs both in the strength and timing of response and also in division of limited resources across multiple competing suppression efforts. Using this framework, we compute optimal strategies for decision making scenarios that arise in fire response policy.

  20. Validation of dynamic torque response of an electrorheological (ER) clutch

    Science.gov (United States)

    Tan, K. P.; Stanway, R.; Bullough, W. A.

    2006-02-01

    It is now well established that using actuators, which have faster speeds of response than d.c. servomotors, can solve the positional errors of the robot arms. One of the possible robotic actuators can be an electro-rheological (ER) clutch. To justify this objective, the authors measured the output torque response of a co-axial ER clutch. However, due to the dynamic inefficiency of a torque transducer, the measured torque response is inaccurate for analytical studies. Therefore, this measured torque is signal processed by using the transfer functions of this torque sensor and a filter to yield the ER torque response. The validity of this ER torque is investigated by comparing the numerical errors between the measured torque and its inverse torque response. From the torque error analysis, it is concluded that the ER clutch can be an actuator to improve the positioning accuracies of the robot arms.

  1. Effects of soil–structure interaction on real time dynamic response of offshore wind turbines on monopiles

    DEFF Research Database (Denmark)

    Damgaard, M.; Zania, Varvara; Andersen, L.V.

    2014-01-01

    , a computationally efficient modelling approach of including the dynamic soil–structure interaction into aeroelastic codes is presented with focus on monopile foundations. Semi-analytical frequency-domain solutions are applied to evaluate the dynamic impedance functions of the soil–pile system at a number......Offshore wind turbines are highly dynamically loaded structures, their response being dominated by the interrelation effects between the turbine and the support structure. Since the dynamic response of wind turbine structures occurs in a frequency range close to the excitation frequencies related...... to environmental and parametric harmonic loads, the effects of the support structure and the subsoil on the natural vibration characteristics of the turbine have to be taken into account during the dynamic simulation of the structural response in order to ensure reliable and cost-effective designs. In this paper...

  2. V-Band Fade Dynamics Characteristics Analysis in Tropical Region

    Directory of Open Access Journals (Sweden)

    Khairayu Badron

    2010-01-01

    Full Text Available Problem statement: Satellite operations at V band in tropical and equatorial regions are constrained as a result of attenuation from rain. Approach: Statistics for 20 consecutive months of V band terrestrial link signal attenuation measurements in Malaysia were presented in this analysis. Such information was considered very pertinent for Earth-space communication link design and can be used for initial groundwork plan for the engineers as well as researchers. Results: The measured statistics were then fittingly scaled up to fit Earth-satellite link. The statistics were then broken down to examine diurnal variations. Characteristics of rain events such as fade duration and inter-fade interval were presented. Conclusion/Recommendations: It is essential to identify such characteristics for the design and implementation of future fade countermeasure techniques on satellite links.

  3. Dynamic corona characteristics of water droplets on charged conductor surface

    Science.gov (United States)

    Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

    2017-03-01

    The formation of the Taylor cone of a water droplet on the surface of the conductor in a line-ground electrode system is captured using a high-speed camera, while the corona current is synchronously measured using a current measurement system. Repeated Taylor cone deformation is observed, yielding regular groupings of corona current pulses. The underlying mechanism of this deformation is studied and the correlation between corona discharge characteristics and cone deformation is investigated. Depending on the applied voltage and rate of water supply, the Taylor cone may be stable or unstable and has a significant influence on the characteristics of the corona currents. If the rate of water supply is large enough, the Taylor cone tends to be unstable and generates corona-current pulses of numerous induced current pulses with low amplitudes. In consequence, this difference suggests that large rainfall results in simultaneously lower radio interference and higher corona loss.

  4. Fluctuation-response relation unifies dynamical behaviors in neural fields

    Science.gov (United States)

    Fung, C. C. Alan; Wong, K. Y. Michael; Mao, Hongzi; Wu, Si

    2015-08-01

    Anticipation is a strategy used by neural fields to compensate for transmission and processing delays during the tracking of dynamical information and can be achieved by slow, localized, inhibitory feedback mechanisms such as short-term synaptic depression, spike-frequency adaptation, or inhibitory feedback from other layers. Based on the translational symmetry of the mobile network states, we derive generic fluctuation-response relations, providing unified predictions that link their tracking behaviors in the presence of external stimuli to the intrinsic dynamics of the neural fields in their absence.

  5. Roadway dynamic response analysis under mining rockburst condition

    Energy Technology Data Exchange (ETDEWEB)

    Chun-rui Li; Qing-xin Qi; Jun-feng Pan; Hang Lan [China Coal Research Institute, Beijing (China). Mining Design and Research Institute

    2009-09-15

    In order to determine how a roadway withstands a momentum wave and determine the extent of damage to rock surrounding the roadway under different force wave peak impacts, the roadway dynamic response state was analysed using numerical simulation method. The roadway's critical peak force wave and fracture region under dynamic wave action were put forward. It is concluded that the method has practical value to roadway support and rockburst prevention.The article is based on the anaysis of Xinwen Mining Group's geologic condition of Xiezhuang 4-2 mine. 4 refs., 4 figs., 1 tab.

  6. Dynamic Response and Fracture of Composite Gun Tubes

    Directory of Open Access Journals (Sweden)

    Jerome T. Tzeng

    2001-01-01

    Full Text Available The fracture behavior due to dynamic response in a composite gun tube subjected to a moving pressure has been investigated. The resonance of stress waves result in very high amplitude and frequency strains in the tube at the instant and location of pressure front passage as the velocity of the projectile approaches a critical value. The cyclic stresses can accelerate crack propagation in the gun tube with an existing imperfection and significantly shorten the fatigue life of gun tubes. The fracture mechanism induced by dynamic amplification effects is particularly critical for composite overwrap barrels because of a multi-material construction, anisotropic material properties, and the potential of thermal degradation.

  7. 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.

  8. 立体组装电路模块动态特性的有限元模拟与分析%Simulation and Analysis of Dynamic Characteristics of 3D Assembly Circuit Module with Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    黄春跃; 周德俭; 黄红艳

    2004-01-01

    Based on the modal analysis theory and by using the dynamics finite element analysis model of a three-dimensional assembly circuit module, dynamic characteristics of circuit module have been studied, including both natural characteristics analysis and dynamic responses analysis. Using a subspace method, modal analysis is first carried out. The first 6 orders of natural frequencies and vibration modes are obtained. Influence of the number of the Z-shaped metal slices on dynamic characteristics of the entire structure is also studied.Harmonic response analysis is then conducted. The steady-state response when the circuit module is subjected to harmonic excitation is determined. A curve of the response values against frequencies is obtained. As a result, the optimal number of Z-shaped metal slices can be determined, and it can be assured that the three-dimensional assembly circuit module has good performance in terms of the dynamic characteristics.

  9. Population dynamics and mutualism: Functional responses of benefits and costs

    Science.gov (United States)

    Holland, J. Nathaniel; DeAngelis, Donald L.; Bronstein, Judith L.

    2002-01-01

    We develop an approach for studying population dynamics resulting from mutualism by employing functional responses based on density‐dependent benefits and costs. These functional responses express how the population growth rate of a mutualist is modified by the density of its partner. We present several possible dependencies of gross benefits and costs, and hence net effects, to a mutualist as functions of the density of its partner. Net effects to mutualists are likely a monotonically saturating or unimodal function of the density of their partner. We show that fundamental differences in the growth, limitation, and dynamics of a population can occur when net effects to that population change linearly, unimodally, or in a saturating fashion. We use the mutualism between senita cactus and its pollinating seed‐eating moth as an example to show the influence of different benefit and cost functional responses on population dynamics and stability of mutualisms. We investigated two mechanisms that may alter this mutualism's functional responses: distribution of eggs among flowers and fruit abortion. Differences in how benefits and costs vary with density can alter the stability of this mutualism. In particular, fruit abortion may allow for a stable equilibrium where none could otherwise exist.

  10. Study on effects of environmental temperature on dynamic characteristics of Taizhou Yangtze River Bridge

    Institute of Scientific and Technical Information of China (English)

    Miao Changqing; Chen Liang; Feng Zhaoxiang

    2011-01-01

    The dynamic characteristics of three-tower and two-span suspension bridge are analyzed at different global temperatures. An equivalent cable inner force method is proposed to consider temperature effects and to study the effects of environmental temperature on dynamic characteristics of Taizhou Yangtze River Bridge. The result demonstrates that the effects of temperature can not be neglected in static or dynamic analysis of Taizhou Yangtze River Bridge. The relationship between temperature and frequency is negative. The effects of temperature should be taken into account in experimental modal analysis of long-span bridges and damage identification.

  11. 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.

  12. Dynamic responses of space solar arrays considering joint clearance and structural flexibility

    Directory of Open Access Journals (Sweden)

    Yuanyuan Li

    2016-06-01

    Full Text Available This article numerically investigates the effects of revolute joint clearance and structural flexibility on the overall dynamic characteristics of a deployable solar array system. Considering torque spring, close cable loop configuration, and lock mechanism, a typical mechanism composed of a main body with a yoke and two panels is used as a demonstration case to study the effects of clearance and flexibility on the dynamic response of the deployable solar array system in the deployment and lock process. The normal contact force model and tangential friction model in clearance joint are established using Lankarani Nikravesh model and modified Coulomb friction model, respectively. The numerical simulation results reveal that the coupling of clearance and flexibility makes different effects on the dynamic characteristics of the deployable space solar arrays for different operation stages. Besides, the clearance and flexibility of a mechanical system play crucial roles in predicting accurately the dynamic response of the system, which is the foundation of mechanism design, precision analysis, and control system design.

  13. 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.

  14. Nonlinear dynamic response of beam and its application in nanomechanical resonator

    Institute of Scientific and Technical Information of China (English)

    Yin Zhang; Yun Liu; Kevin D. Murphy

    2012-01-01

    Nonlinear dynamic response of nanomechanical resonator is of very important characteristics in its application.Two categories of the tension-dominant and curvaturedominant nonlinearities are analyzed.The dynamic nonlinearity of four beam structures of nanomechanical resonator is quantitatively studied via a dimensional analysis approach.The dimensional analysis shows that for the nanomechanical resonator of tension-dominant nonlinearity,its dynamic nonlinearity decreases monotonically with increasing axial loading and increases monotonically with the increasing aspect ratio of length to thickness; the dynamic nonlinearity can only result in the hardening effects.However,for the nanomechanical resonator of the curvature-dominant nonlinearity,its dynamic nonlinearity is only dependent on axial loading.Compared with the tension-dominant nonlinearity,the curvature-dominant nonlinearity increases monotonically with increasing axial loading; its dynamic nonlinearity can result in both hardening and softening effects.The analysis on the dynamic nonlinearity can be very helpful to the tuning application of the nanomechanical resonator.

  15. Influence of Surface Irregularities on the Dynamic Response of Minor Highway Bridges

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.; Kirkegaard, Poul Henning

    are included into the model. Based on a Monte Carlo simulation study the mean value and the variational coefficient of several dynamic amplification factors have been calculated assuming the parameters describing the vehicle and the bridge deterministic at characteristic values. The overall conclusion from......In the present paper the effect on the dynamic application factor of bridge response from the surface irregularities is investigated. A numerical 3D model has been formulated for a 48t Scania truck. Further, a characteristic minor highway bridge has been selected, and a numerical FEM-model has been...... formulated. Based on measured data, a 2D spectral description of the road roughness is established which models the deterministic trends in transversal (wheel tracking) as well as longitudinal direction (some long-waved tendency). Further, the bumps/ expansion joints at the approaches to the bridge...

  16. Fluid Compressibility Effects on the Dynamic Response of Hydrostatic Journal Bearings

    Science.gov (United States)

    Sanandres, Luis A.

    1991-01-01

    A theoretical analysis for the dynamic performance characteristics of laminar flow, capillar/orifice compensated hydrostatic journal bearings is presented. The analysis considers in detail the effect of fluid compressibility in the bearing recesses. At high frequency excitations beyond a break frequency, the bearing hydrostatic stiffness increases sharply and it is accompanied by a rapid decrease in direct damping. Also, the potential of pneumatic hammer instability (negative damping) at low frequencies is likely to occur in hydrostatic bearing applications handling highly compressible fluids. Useful design criteria to avoid undesirable dynamic operating conditions at low and high frequencies are determined. The effect of fluid recess compressibility is brought into perspective, and found to be of utmost importance on the entire frequency spectrum response and stability characteristics of hydrostatic/hybrid journal bearings.

  17. Evolutionary network games: Imitation and Best-Response dynamics

    CERN Document Server

    Cimini, Giulio; Sánchez, Angel

    2014-01-01

    We consider games of strategic substitutes and strategic complements on networks. We introduce two different evolutionary dynamics in order to refine their multiplicity of equilibria, that can be related to alternative informational contexts. We find that for the best-shot game, taken as a model for substitutes, a replicator-like dynamics does not lead to Nash equilibria, whereas it leads to unique equilibria (full cooperation or full defection, depending on the initial condition and the game parameter) for complements, represented by a coordination game. On the other hand, when the dynamics becomes more cognitively demanding in the form of a best response evolution, predictions are always Nash equilibria (at least when individuals are fully rational): For the best-shot game we find equilibria with a definite value of the fraction of contributors, whereas for the coordination game symmetric equilibria arise only for low or high initial fractions of cooperators. We also consider extensions of the natural incom...

  18. The effects of bolted joints on dynamic response of structures

    Science.gov (United States)

    Zaman, I.; Khalid, A.; Manshoor, B.; Araby, S.; Ghazali, M. I.

    2013-12-01

    Joint is an universal fastening technology for structural members; in particular bolted joints are extensively used in mechanical structures due to their simple maintenance and low cost. However, the components of bolted joints are imperative because failure could be catastrophic and endanger lives. Hence, in this study, the effects of bolted joints on vibrating structures are investigated by determining the structural dynamic properties, such as mode shapes, damping ratios and natural frequencies, and these are compared with the monolithic structures (welding). Two approaches of experimental rigs are developed: a beam and a frame where both are subjected to dynamic loading. The analysis reveals the importance of bolted joints in increasing the damping properties and minimizing the vibration magnitude of structures, this indicates the significant influence of bolted joints on the dynamic behaviour of assembled structures. The outcome of this study provides a good model for predicting the experimental variable response in different types of structural joints.

  19. Dynamic characteristics of resonant gyroscopes study based on the Mathieu equation approximate solution

    Institute of Scientific and Technical Information of China (English)

    Fan Shang-Chun; Li Yan; Guo Zhan-She; Li Jing; Zhuang Hai-Han

    2012-01-01

    Dynamic characteristics of the resonant gyroscope are studied based on the Mathieu equation approximate solution in this paper.The Mathieu equation is used to analyze the parametric resonant characteristics and the approximate output of the resonant gyroscope.The method of small parameter perturbation is used to analyze the approximate solution of the Mathieu equation.The theoretical analysis and the numerical simulations show that the approximate solution of the Mathieu equation is close to the dynamic output characteristics of the resonant gyroscope.The experimental analysis shows that the theoretical curve and the experimental data processing results coincide perfectly,which means that the approximate solution of the Mathieu equation can present the dynamic output characteristic of the resonant gyroscope.The theoretical approach and the experimental results of the Mathieu equation approximate solution are obtained,which provides a reference for the robust design of the resonant gyroscope.

  20. Dynamic characteristics of peripheral jet ACV. I - Heaving motion

    Science.gov (United States)

    Mori, T.; Maeda, H.

    The theory of the dynamics of peripheral jet ACV is presented. The flow patterns under the bottom of the ACV are classified into two types, i.e. underfed and overfed regimes. The mathematical models associated with such regimes are presented and the equations of those models are derived. The forced heaving oscillation of a two-dimensional ACV model is investigated experimentally and variations of cushion pressure and lift force are measured and compared with the results obtained by the numerical calculation. The coincidence of these two results seems to be reasonable. The heaving motion of ACV which is induced by the simple harmonic oscillation of the ground board is also analyzed numerically.

  1. Noninvasive Monitoring of Soil Static Characteristics and Dynamic States

    DEFF Research Database (Denmark)

    Cassiani, Giorgio; Ursino, Nadia; Deiana, Rita

    2012-01-01

    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......In this paper we present the results of seasonal monitoring and irrigation tests performed on an experimental farm in a semiarid region of Southern Sardinia. The goal of the study is to understand the soil–vegetation interactions and how they can affect the soil water balance, particularly in view...... 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...

  2. Satellite Aerodynamics and Density Determination from Satellite Dynamic Response

    Science.gov (United States)

    Karr, G. R.

    1972-01-01

    The aerodynamic drag and lift properties of a satellite are first expressed as a function of two parameters associated with gas-surface interaction at the satellite surface. The dynamic response of the satellite as it passes through the atmosphere is then expressed as a function of the two gas-surface interaction parameters, the atmospheric density, the satellite velocity, and the satellite orientation to the high speed flow. By proper correlation of the observed dynamic response with the changing angle of attack of the satellite, it is found that the two unknown gas-surface interaction parameters can be determined. Once the gas-surface interaction parameters are known, the aerodynamic properties of the satellite at all angles of attack are also determined.

  3. Exploring the Dynamics of Responses to Food Production Shocks

    Directory of Open Access Journals (Sweden)

    Aled Jones

    2017-06-01

    Full Text Available Food production shocks can lead to food crises where access to appropriate quantities and quality of food become inadequate, unaffordable, or unreliable on a major scale. While the physical causes of food production shocks are well researched, the dynamics of responses to them are less well understood. This paper reviews those dynamics and includes evidence gathered via interviews of 44 expert practitioners sourced globally from academia, government, industry, think-tanks, and development/relief organizations. The paper confirms that policy interventions are often prioritised for national interests and poorly coordinated at regional and global scales. The paper acknowledges future compounding trends such as climate change and demographic shifts and suggests that while there are signs of incremental progress in better managing the impacts of shock events, coordinated responses at scale will require a paradigm shift involving major policy, market, and technological advancements, and a wide range of public and private sector stakeholders.

  4. Using dissipative particle dynamics to model micromechanics of responsive hydrogels

    Science.gov (United States)

    Alexeev, Alexander; Nikolov, Svetoslav; Fernandez de Las Nieves, Alberto

    2015-03-01

    The ability of responsive hydrogels to undergo complex and reversible shape transformations in response to external stimuli such as temperature, magnetic/electric fields, pH levels, and light intensity has made them the material of choice for tissue scaffolding, drug delivery, bio-adhesive, bio-sensing, and micro-sorting applications. The complex micromechanics and kinetics of these responsive networks however, currently hinders developments in the aforementioned areas. In order to better understand the mechanical properties of these systems and how they change during the volume transition we have developed a dissipative particle dynamics (DPD) model for responsive polymer networks. We use this model to examine the impact of the Flory-Huggins parameter on the bulk and shear moduli. In this fashion we evaluate how environmental factors can affect the micromechanical properties of these networks. Support from NSF CAREER Award (DMR-1255288) is gratefully acknowledged.

  5. Effect of Initial Principal Stress Direction on the Dynamic Characteristics of Carbonate Sand

    Institute of Scientific and Technical Information of China (English)

    Yu Haizhen; Zhao Wenguang; Wang Ren; Li Jianguo; He Yang

    2005-01-01

    The dynamic characteristics of carbonate sand under wave loads are very important for constructions on the ocean floor. The initial principal stress direction has been known to exert some influence on the dynamic characteristics of sand during cyclic loading. In an effort to investigate this aspect of the problem, several series of cyclic undrained tests were carried out on a saturated and loose sample of carbonate sand using a geotechnical static and dynamic universal triaxial shear apparatus. In this test apparatus, a hollow cylindrical sand specimen is subjected to a simultaneous application of both triaxial and torsional modes of shear stresses, which brings about the continuous rotation of principal stress axes. The test results indicated that the initial principal stress direction has a considerable influence on the dynamic strength of loose carbonate sand and with the increase of initial orientation of principal stress, dynamic strength will be reduced, the cyclic pore pressure increased, but the residual pore pressure reduced.

  6. A Dynamic Market Mechanism for Markets with Shiftable Demand Response

    DEFF Research Database (Denmark)

    Hansen, Jacob; Knudsen, Jesper Viese; Kiani, Arman

    2014-01-01

    renewables, this mechanism accommodates both consumers with a shiftable Demand Response and an adjustable Demand Response. The overall market mechanism is evaluated in a Day Ahead Market and is shown in a numerical example to result in a reduction of the cost of electricity for the consumer, as well......In this paper, we propose a dynamic market mechanism that converges to the desired market equilibrium. Both locational marginal prices and the schedules for generation and consumption are determined through a negotiation process between the key market players. In addition to incorporating...

  7. Note: A high dynamic range, linear response transimpedance amplifier.

    Science.gov (United States)

    Eckel, S; Sushkov, A O; Lamoreaux, S K

    2012-02-01

    We have built a high dynamic range (nine decade) transimpedance amplifier with a linear response. The amplifier uses junction-gate field effect transistors (JFETs) to switch between three different resistors in the feedback of a low input bias current operational amplifier. This allows for the creation of multiple outputs, each with a linear response and a different transimpedance gain. The overall bandwidth of the transimpedance amplifier is set by the bandwidth of the most sensitive range. For our application, we demonstrate a three-stage amplifier with transimpedance gains of approximately 10(9)Ω, 3 × 10(7)Ω, and 10(4)Ω with a bandwidth of 100 Hz.

  8. Effect of Concrete Cracks on Dynamic Characteristics of Powerhouse for Giant-Scale Hydrostation

    Institute of Scientific and Technical Information of China (English)

    TIAN Ziain; ZHANG Yunliang; MA Zhenvue; CHEN Jing

    2008-01-01

    With the increase of capacity and size of the hydro-generator unit, the spiral case be-comes a more super-giant hydraulic structure with very high hid value, where H and D denote water head and maximum intake diameter of spiral case, respectively. Due to the induced lower stiffness by the more giant size and adverse operation conditions, dynamic performances of the powerhouse and the supporting structure for the giant units have become more important and attracted much attention. If the manner of steel spiral case embedded directly in concrete is adopted, on some locations of the concrete surrounding the spiral case, distributed and concentrated cracks will emerge due to high tensile stress. Although the concrete is reinforced well to control the maximum crack width, definitely these cracks will reduce the local and entire stiffness of the powerhouse.Under dynamic loads such as hydraulic forces including water pressure pulsation in flow passage acting on the structure, effect of the cracks on the dynamic characteristics of the local members and entire structure needs to be evaluated. However, research on this subject is few in hydroelectric engineering. In this paper, Three-Gorge Project was taken as an example to evaluate effect of such cracks on natural frequencies and the vibration responses of the powerhouse under hydraulic and earthquake forces in detail. Results show that cracks only reduce the local structural stiffness greatly but have little effect on the entire powerhouse especially the superstructure; vibrations of powerhouse with cracks in concrete surrounding the spiral case are still under the design limits.Results in this paper have been verified by practice of Three-Gorge Project.

  9. Spatially dispersive dynamical response of hot carriers in doped graphene

    OpenAIRE

    Kukhtaruk, S. M.; V. A. Kochelap; Sokolov, V. N.; Kim, K. W.

    2015-01-01

    We study theoretically wave-vector and frequency dispersion of the complex dynamic conductivity tensor (DCT), $\\sigma_{lm}(\\mathbf{k}, \\omega)$, of doped monolayer graphene under a strong dc electric field. For a general analysis, we consider the weak ac field of arbitrary configuration given by two independent vectors, the ac field polarization and the wave vector $\\mathbf{k}$. The high-field transport and linear response to the ac field are described on the base of the Boltzmann kinetic equ...

  10. Dynamic Simulation of the Tank Gun Recoil Response

    Institute of Scientific and Technical Information of China (English)

    XING Jun-wen; WANG Liang-xi; SHI Yan; CHEN Chun-liang

    2005-01-01

    By using the ATV module of MSC. ADAMS, the dynamic simulation of recoil response of tank gun is analyzed.How the recoil force affects the bodywork and the suspension during gun firing, as well as the changing status of the gun muzzle's velocity are gained. All results and analyzing methods are offered for the designing basis of optimizing tank vehicle-gun match. The constructive exploration is beneficial to improving the general capability of tank.

  11. Dynamic characteristics and simulation of traffic flow with slope

    Institute of Scientific and Technical Information of China (English)

    He Hong-Di; Lu Wei-Zhen; Xue Yu; Dong Li-Yun

    2009-01-01

    This paper proposes a new traffic model to describe traffic flow with slope under consideration of the gravity effect. Based on the model, stability analysis is conducted and a numerical simulation is performed to explore the characteristics of the traffic flow with slope. The result shows that the perturbation of the system is an inherent one,which is induced by the slope. In addition, the hysteresis loop is represented through plotting the figure of velocity against headway and highly depends on the slope angle. The kinematic wave at high density is also obtained through reproducing the phenomenon of stop-and-go traffic, which is significant to explore the phase transition of traffic flow and the evolution of traffic congestion.

  12. Dynamic structure of joint-action stimulus-response activity.

    Science.gov (United States)

    Malone, MaryLauren; Castillo, Ramon D; Kloos, Heidi; Holden, John G; Richardson, Michael J

    2014-01-01

    The mere presence of a co-actor can influence an individual's response behavior. For instance, a social Simon effect has been observed when two individuals perform a Go/No-Go response to one of two stimuli in the presence of each other, but not when they perform the same task alone. Such effects are argued to provide evidence that individuals co-represent the task goals and the to-be-performed actions of a co-actor. Motivated by the complex-systems approach, the present study was designed to investigate an alternative hypothesis--that such joint-action effects are due to a dynamical (time-evolving) interpersonal coupling that operates to perturb the behavior of socially situated actors. To investigate this possibility, participants performed a standard Go/No-Go Simon task in joint and individual conditions. The dynamic structure of recorded reaction times was examined using fractal statistics and instantaneous cross-correlation. Consistent with our hypothesis that participants responding in a shared space would become behaviorally coupled, the analyses revealed that reaction times in the joint condition displayed decreased fractal structure (indicative of interpersonal perturbation processes modulating ongoing participant behavior) compared to the individual condition, and were more correlated across a range of time-scales compared to the reaction times of pseudo-pair controls. Collectively, the findings imply that dynamic processes might underlie social stimulus-response compatibility effects and shape joint cognitive processes in general.

  13. Dynamic structure of joint-action stimulus-response activity.

    Directory of Open Access Journals (Sweden)

    MaryLauren Malone

    Full Text Available The mere presence of a co-actor can influence an individual's response behavior. For instance, a social Simon effect has been observed when two individuals perform a Go/No-Go response to one of two stimuli in the presence of each other, but not when they perform the same task alone. Such effects are argued to provide evidence that individuals co-represent the task goals and the to-be-performed actions of a co-actor. Motivated by the complex-systems approach, the present study was designed to investigate an alternative hypothesis--that such joint-action effects are due to a dynamical (time-evolving interpersonal coupling that operates to perturb the behavior of socially situated actors. To investigate this possibility, participants performed a standard Go/No-Go Simon task in joint and individual conditions. The dynamic structure of recorded reaction times was examined using fractal statistics and instantaneous cross-correlation. Consistent with our hypothesis that participants responding in a shared space would become behaviorally coupled, the analyses revealed that reaction times in the joint condition displayed decreased fractal structure (indicative of interpersonal perturbation processes modulating ongoing participant behavior compared to the individual condition, and were more correlated across a range of time-scales compared to the reaction times of pseudo-pair controls. Collectively, the findings imply that dynamic processes might underlie social stimulus-response compatibility effects and shape joint cognitive processes in general.

  14. ASCERTAINMENT OF DYNAMIC CHARACTERISTICS OF THE INDUSTRIAL FACILITIES BY MEANS OF STOCHASTIC ACTIONS

    Directory of Open Access Journals (Sweden)

    Ya. А. Gusentsova

    2016-01-01

    Full Text Available The paper presents comparison of different methods for identifying the dynamic characteristics of objects associated with thermal energy generation or the medium cooling in the cooling systems of internal-combustion engines. Reaction identification to the reference exposure is considered, videlicet – stepwise, impulse and harmonic. The study shows that on a number of occasions for the type of objects being involved their application is unacceptable. In those instances it is expediential to apply statistical characteristics of the input and output signals, i. a. to employ the data of so-called passive experiment. In which case the task is divisible into two stages – determination of statistical characteristics of the variates at the ins and outs of the object and calculation of the dynamic characteristics based on them. The statistical characteristics of the variates at the input and output are obtained through time averaging of values of the variates dependent on the ordinate of the processes. Inasmuch as stochastic processes occurring in the objects under examination possess ergodic property, their averaged values are constant. All the data required for calculating characteristics of the linear systems appears in their correlative functions. Heat generating objects as well as the cooling systems of internal-combustion engines are the objects fed back by the regulator. Therefore, in this instance cross-correlated functions are employed for determining their dynamic characteristics. The suggested random-input analytical method for dynamic characteristics constitutes a good match with the results of active experiments reported in a variety of sources. This allows recommending the random signals estimation method of dynamic characteristics for the involved type of objects. 

  15. Neighborhood structure effects on the Dynamic response of soil-structure interaction by harmonic analysis

    Directory of Open Access Journals (Sweden)

    Pan Dan-guang

    2015-01-01

    Full Text Available For realizing the variation of structural dynamic characteristics due to neighbor structure in buildings group, the surface structure is idealized as an equivalent single degree of freedom system with rigid base whose site consists of a single homogeneous layer. Based on the model, a equivalent method on the equivalent seismic excitation is proposed. Then, the differences of seismic response and equivalent seismic input between soil - structure interaction (SSI system and structure -soil-structure interaction (SSSI system are investigated by harmonic analysis. The numerical results show that dynamic responses would be underestimated in SSSI system when the forcing frequencies are close to the Natural frequency if the effects of neighborhood structure were ignored. Neighborhood structure would make the translational displacement increase and rocking vibration decrease. When establishing an effective seismic input, it is necessary to consider the impact of inertia interaction.

  16. On characteristic modeling of a class of flight vehicles’attitude dynamics

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The characteristic modeling problem of flight vehicles’attitude dynamics is considered in this paper.In terms of the affine nonlinear system with triangle form of flight vehicles’attitude dynamics,a general method is presented to compress the dynamics into the characteristic model parameters,by introducing the time scale of nonlinear systems and a class of system states related compress functions.The parameter region and limit of the characteristic model are also given.From the given parameter region it is seen that the bound of the characteristic model parameters is dependent on the sampling period,the modeling error,the system order and the system change rate.The modeling error of the established characteristic model can be arbitrarily small according to the control precision,showing the difference between the characteristic model and other model reduction methods,that is,no system information is lost using this approach.On the basis of this modeling approach,the characteristic model of the flexible satellite attitude is established,as well as the bound and limit of the parameters,which sets a theoretical foundation for characteristic model based control design of flight vehicles.

  17. Static and Dynamic Characteristic Simulation of Feed System Driven by Linear Motor in High Speed Computer Numerical Control Lathe

    Directory of Open Access Journals (Sweden)

    Yang Zeqing

    2013-07-01

    Full Text Available In order to design the feed system of high speed Computer Numerical Control (CNC lathe, the static and dynamic characteristics of feed system driven by linear motor in high speed CNC lathe were analyzed. The slide board was taking as the main moving part of the feed system, and the guide rail was the main support component of the linear motor feed system. The mechanical structure static stiffness of feed system is researched through the slide board statics analysis. The simulation results show that the maximum deformation of the slide board occurs in the middle of the slide board where the linear motor is placed. The linear motor feed system control model was established based on analysis of high-speed linear feed system control principle, and the linear motor feed system transfer function was established, and servo dynamic stiffness factors were analyzed. The control parameters of the servo system and actuating mechanism parameters of feed system on the effect of the linear motor servo dynamic stiffness were analyzed using MATLAB software. The simulation results show that the position loop proportional gain, speed loop proportional gain and speed loop integral response time are the biggest influence factors on servo dynamic stiffness. The displacement response is reduced under the cutting interference force step inputting, the servo dynamic stiffness is increased, the number of system oscillation is also reduced, and the system tends to be stable.  

  18. 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 seconds of freefall (0 g) followed by 40 seconds 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.

  19. The dynamics of parabolic flight: flight characteristics and passenger percepts

    Science.gov (United States)

    Karmali, Faisal; Shelhamer, Mark

    2008-01-01

    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 seconds of freefall (0 g) followed by 40 seconds 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. PMID:19727328

  20. Dynamic response analysis of the equivalent water depth truncated point of the catenary mooring line

    Science.gov (United States)

    Zhang, Huo-ming; Kong, Ling-bin; Guan, Wei-bing; Huang, Sai-hua; Fang, Gui-sheng

    2017-03-01

    The real-time computer-controlled actuators are used to connect the truncated parts of moorings and risers in the active hybrid model testing system. This must be able to work in model-scale real time, based on feedback input from the floater motions. Thus, mooring line dynamics and damping effects are artificially simulated in real time, based on a computer-based model of the problem. In consideration of the nonlinear characteristics of the sea platform catenary mooring line, the equations of the mooring line motion are formulated by using the lumped-mass method and the dynamic response of several points on the mooring line is investigated by the time and frequency domain analysis method. The dynamic response of the representative point on the mooring line is analyzed under the condition of two different corresponding upper endpoint movements namely sine wave excitation and random wave excitation. The corresponding laws of the dynamic response between the equivalent water depth truncated points at different locations and the upper endpoint are obtained, which can provide technical support for further study of the active hybrid model test.

  1. Dynamic Response during PEM Fuel Cell Loading-up

    OpenAIRE

    Jun Gou; Pengcheng Li; Xing Yuan; Pucheng Pei

    2009-01-01

    A study on the effects of controlling and operating parameters for a Proton Exchange Membrane (PEM) fuel cell on the dynamic phenomena during the loading-up process is presented. The effect of the four parameters of load-up amplitudes and rates, operating pressures and current levels on gas supply or even starvation in the flow field is analyzed based accordingly on the transient characteristics of current output and voltage. Experiments are carried out in a single fuel cell with an active ar...

  2. Study of the Dynamic Characteristics of Ball Screw with a Load Disturbance

    Directory of Open Access Journals (Sweden)

    Zhe Du

    2016-01-01

    Full Text Available The dynamic character of ball screw is the key factor that influences the machining accuracy of numerical control (NC machine tool. To improve the dynamic characteristics of the NC machine tool, it is necessary to study the dynamic characteristics of a ball screw. In this paper, the kinematics of a ball screw mechanism (BSM are studied to expound the dynamic process of the drive, and the load disturbance is considered to analyze the contact deformation based on the Hertzian contact theory. The velocity relationships among the ball, screw, and nut are analyzed, and the influence of the contact deformation on the dynamic characteristics is simulated and investigated experimentally. The results show that the relationships between the contact deformation, which is affected by the material characteristics, the contact angle, and the load of nut are nonlinear. The contact deformation is a factor that cannot be ignored when considering the dynamic machining error of high-speed and high-precision machine tools.

  3. Effect of tube-support interaction on the dynamic responses of heat exchanger tubes. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Y.S.; Jendrzejczyk, J.A.; Wambsganss, M.W.

    1977-01-01

    Operating heat exchangers have experienced tube damages due to excessive flow-induced vibration. The relatively small inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the tube vibrational characteristics. In attempting a theoretical analysis, questions arise as to the effects of tube-baffle impacting on dynamic responses. Experiments were performed to determine the effects of tube-baffle impacting in vertical/horizontal tube orientation, and in air/water medium on the vibrational characteristics (resonant frequencies, mode shapes, and damping) and displacement response amplitudes of a seven-span tube model. The tube and support conditions were prototypic, and overall length approximately one-third that of a straight tube segment of the steam generator designed for the CRBR. The test results were compared with the analytical results based on the multispan beam with ''knife-edge'' supports.

  4. [Grain filling dynamics and germination characteristics of Bupleurum chinense seeds].

    Science.gov (United States)

    Jin, Xin; Ren, Bing; Cao, Ai-Nong; Jin, Xiao-Jun

    2014-10-01

    Bupleurum chinense used in the study were cultivated in the experimental fields of Gansu agricultural University for three years. The seeds of B. chinense were collected every 3 days 10 d after the blossom. The result showed that the 1 000-grain fresh weight reached the maximum 43 d after the blossom and then decreased rapidly, at the mature period the fresh weight of seeds were falling to the same level of the dry weight. The dynamic change of the grain dry matter accumulation showed as an S-shape curve, the rapid increase stage was 25-34 d following the flower, and the grain filling was ended 46 d after blossom. Grain filling rate was under the law "fast-slow-fast-slow". And there were two peaks of grain filling rate appeared, after reached the second peak 28 d after the flower the filling rate decreased rapidly and stayed steadily 43 d after flowering. The dehydration rate was also measured at its maximum 43 d following flower. The indexes of seeds all reached the top 52 days following the blossom, when the germination rate reached the peak (34.33%) and water content of seeds was near 10%. The rate of germination and the 1 000-graid weight of seed showed significant positive correlation, while the water content of seeds was found significant negatively correlation with germination percentage. So the best time for harvest should be 52 d after flowering (9 month), the seeds collected at that time showed both high quality and germination rate.

  5. COMMUNICATION: Electrophysiological response dynamics during focal cortical infarction

    Science.gov (United States)

    Chiganos, Terry C., Jr.; Jensen, Winnie; Rousche, Patrick J.

    2006-12-01

    While the intracellular processes of hypoxia-induced necrosis and the intercellular mechanisms of post-ischemic neurotoxicity associated with stroke are well documented, the dynamic electrophysiological (EP) response of neurons within the core or periinfarct zone remains unclear. The present study validates a method for continuous measurement of the local EP responses during focal cortical infarction induced via photothrombosis. Single microwire electrodes were acutely implanted into the primary auditory cortex of eight rats. Multi-unit neural activity, evoked via a continuous 2 Hz click stimulus, was recorded before, during and after infarction to assess neuronal function in response to local, permanent ischemia. During sham infarction, the average stimulus-evoked peak firing rate over 20 min remained stable at 495.5 ± 14.5 spikes s-1, indicating temporal stability of neural function under normal conditions. Stimulus-evoked peak firing was reliably reduced to background levels (firing frequency in the absence of stimulus) following initiation of photothrombosis over a period of 439 ± 92 s. The post-infarction firing patterns exhibited unique temporal degradation of the peak firing rate, suggesting a variable response to ischemic challenge. Despite the inherent complexity of cerebral ischemia secondary to microvascular occlusion, complete loss of EP function consistently occurred 300-600 s after photothrombosis. The results suggest that microwire recording during photothrombosis provides a simple and highly efficacious strategy for assessing the electrophysiological dynamics of cortical infarction.

  6. 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.

  7. SMA Hybrid Composites for Dynamic Response Abatement Applications

    Science.gov (United States)

    Turner, Travis L.

    2000-01-01

    A recently developed constitutive model and a finite element formulation for predicting the thermomechanical response of Shape Memory Alloy (SMA) hybrid composite (SMAHC) structures is briefly described. Attention is focused on constrained recovery behavior in this study, but the constitutive formulation is also capable of modeling restrained or free recovery. Numerical results are shown for glass/epoxy panel specimens with embedded Nitinol actuators subjected to thermal and acoustic loads. Control of thermal buckling, random response, sonic fatigue, and transmission loss are demonstrated and compared to conventional approaches including addition of conventional composite layers and a constrained layer damping treatment. Embedded SMA actuators are shown to be significantly more effective in dynamic response abatement applications than the conventional approaches and are attractive for combination with other passive and/or active approaches.

  8. Dynamic response and modeling of a carbon fiber— epoxy composite subject to shock loading

    Science.gov (United States)

    Alexander, C. S.; Key, C. T.; Schumacher, S. C.

    2013-12-01

    Unidirectional carbon fiber reinforced epoxy composite samples were tested to determine their response to one dimensional shock loading with the ultimate goal of developing a micromechanics based numerical model of the dynamic response. The material tested had high fiber content (62-68% by volume) and low porosity. Wave speeds for shocks traveling along the carbon fibers are significantly higher than for those traveling transverse to the fibers or through the bulk epoxy. As a result, the dynamic material response is dependent on the relative shock—fiber orientation; a complication that must be captured in the numerical models. Shocks traveling transverse to the fibers show an inelastic response consistent with the material constituent parts. Shocks traveling along the fiber direction travel faster and exhibit both elastic and plastic characteristics over the stress range tested; up to 15 GPa. Results presented detail the anisotropic material response, which is governed by different mechanisms along each of the two principle directions in the composite. Finally, numerical modeling of this response is described in detail and validated against the experimental data.

  9. Influence of atomic vacancies on the dynamic characteristics of nanoresonators based on double walled carbon nanotube

    Science.gov (United States)

    Patel, Ajay M.; Joshi, Anand Y.

    2015-06-01

    The dynamic analysis of double walled carbon nanotubes (DWCNTs) with different boundary conditions has been performed using atomistic finite element method. The double walled carbon nanotube is modeled considering it as a space frame structure similar to a three dimensional beam. The elastic properties of beam element are calculated by considering mechanical characteristics of covalent bonds between the carbon atoms in the hexagonal lattice. Spring elements are used to describe the interlayer interactions between the inner and outer tubes caused due to the van der Waals forces. The mass of each beam element is assumed as point mass at nodes coinciding with carbon atoms at inner and outer wall of DWCNT. It has been reported that atomic vacancies are formed during the manufacturing process in DWCNT which tend to migrate leading to a change in the mechanical characteristics of the same. Simulations have been carried out to visualize the behavior of such defective DWCNTs subjected to different boundary conditions and when used as mass sensing devices. The variation of such atomic vacancies in outer wall of Zigzag and Armchair DWCNT is performed along the length and the change in response is noted. Moreover, as CNTs have been used as mass sensors extensively, the present approach is focused to explore the use of zigzag and armchair DWCNT as sensing device with a mono-atomic vacancy in it. The results clearly state that the dynamic characteristics are greatly influenced by defects like vacancies in it. A higher frequency shift is observed when the vacancy is located away from the fixed end for both Armchair as well as zigzag type of CNTs. A higher frequency shift is reported for armchair CNT for a mass of 10-22 g which remains constant for 10-21 g and then decreases gradually. Comparison with the other experimental and theoretical studies exhibits good association which suggests that defective DWCNTs can further be explored for mass sensing. This investigation is helpful

  10. Dynamic Responses of Truss Spar Due to Wave Actions

    Directory of Open Access Journals (Sweden)

    V.J. Kurian

    2013-01-01

    Full Text Available Spar platforms have been used for drilling, production and storage of oil and gas in the offshore deepwater region. The structure is installed at the deepwater locations in the sea and is exposed to continuous action of wind, wave, current and other environmental forces. Wave force constitutes about 70% of the total environmental force and could be considered as the most significant force affecting the dynamic responses needed for the design of these structures. In this study, the dynamic responses of the truss spar due to wave actions including the wave force theories and wave propagation directions are investigated. Numerical simulations are developed to investigate the accuracy of the wave force theories i.e., Morison equation and Diffraction theory, for large structure such as truss spar. The investigation is further expanded to study responses of the truss spar due to variations directions of the wave propagated. The truss spar is modelled as a rigid body with three degrees of freedom restrained by mooring lines. In the simulation, the mass, damping and stiffness matrices are evaluated at every time step. The equations of motion are formulated for the platform dynamic equilibrium and solved by using Newmark Beta method. To compute the wave force for truss spar, which is large compared to the wave length, Diffraction theory was found to be more appropriate. The Morison equation was found applicable only at the high frequency range. Short crested waves resulted in smaller responses in all the motions than that for long crested waves. Hence, it would be appropriate to consider the short crested wave statistics for the optimum design.

  11. Study on dynamic characteristics' change of hippocampal neuron reduced models caused by the Alzheimer's disease.

    Science.gov (United States)

    Peng, Yueping; Wang, Jue; Zheng, Chongxun

    2016-01-01

    In the paper, based on the electrophysiological experimental data, the Hippocampal neuron reduced model under the pathology condition of Alzheimer's disease (AD) has been built by modifying parameters' values. The reduced neuron model's dynamic characteristics under effect of AD are comparatively studied. Under direct current stimulation, compared with the normal neuron model, the AD neuron model's dynamic characteristics have obviously been changed. The neuron model under the AD condition undergoes supercritical Andronov-Hopf bifurcation from the rest state to the continuous discharge state. It is different from the neuron model under the normal condition, which undergoes saddle-node bifurcation. So, the neuron model changes into a resonator with monostable state from an integrator with bistable state under AD's action. The research reveals the neuron model's dynamic characteristics' changing under effect of AD, and provides some theoretic basis for AD research by neurodynamics theory.

  12. Prediction for Dynamic Characteristics of Ring-Plate Planetary Indexing Cam Mechanism

    Institute of Scientific and Technical Information of China (English)

    SONG Yimin; TIAN Guangcai; ZHANG Jun; LIU Mingtao; LIU Jianping

    2009-01-01

    This paper is aimed to propose an approach to predict the dynamic characteristics of ring-plate planetary indexing cam mechanism, which is a novel type of indexing mechanism that employs internal planetary transmis-sion structure. Firstly, the geometry and structure of the mechanism are discussed and the kinematic practicability is simulated with virtual prototype design. Then a 3D finite element model of the ring-plate planetary indexing cam mechanism is developed with the commercial software of MATLAB and ANSYS. Through the finite element analysis, the natural frequencies and the corresponding mode shapes are predicted in one motion cycle. On the basis of the virtual prototype design and finite element analysis, an experimental prototype is made and tested to validate the prediction of the dynamic characteristics. The agreement between experimental results and the finite element analysis testifies that the finite element model developed is applicable to the prediction of the dynamic characteris-tics of this type of mechanism.

  13. Compressibility effects on the dynamic characteristics of gas lubricated mechanical components

    Science.gov (United States)

    Arghir, Mihai; Matta, Pierre

    2009-11-01

    The present Note deals with the effects of compressibility on the linearized dynamic characteristics of gas lubricated mechanical components (journal and thrust bearings). Although the effect of compressibility on the static characteristics is well known, its influence on the dynamic characteristics is still not clearly understood. The present Note uses Lubrication's simplest model problems (the 1D slider) to qualitatively describe this effect. An analytic solution obtained for the parallel 1D slider depicts the variation of stiffness and damping with the excitation frequency and shows that this nonlinearity must be taken into account for squeeze number larger than 1. A convenient way of handling this nonlinearity in a dynamic system is described for an aerodynamic thrust bearing. To cite this article: M. Arghir, P. Matta, C. R. Mecanique 337 (2009).

  14. Characteristic Classes of SL(N)-Bundles and Quantum Dynamical Elliptic R-Matrices

    CERN Document Server

    Levin, A; Smirnov, A; Zotov, A

    2012-01-01

    We discuss quantum dynamical elliptic R-matrices related to arbitrary complex simple Lie group G. They generalize the known vertex and dynamical R-matrices and play an intermediate role between these two types. The R-matrices are defined by the corresponding characteristic classes describing the underlying vector bundles. The latter are related to elements of the center Z(G) of G. While the known dynamical R-matrices are related to the bundles with trivial characteristic classes, the Baxter-Belavin-Drinfeld-Sklyanin vertex R-matrix corresponds to the generator of the center Z_N of SL(N). We construct the R-matrices related to SL(N)- bundles with an arbitrary characteristic class explicitly and discuss the corresponding IRF models.

  15. Dynamic Characterization and Impulse Response Modeling of Amplitude and Phase Response of Silicon Nanowires

    DEFF Research Database (Denmark)

    Cleary, Ciaran S.; Ji, Hua; Dailey, James M.

    2013-01-01

    Amplitude and phase dynamics of silicon nanowires were measured using time-resolved spectroscopy. Time shifts of the maximum phase change and minimum amplitude as a function of pump power due to saturation of the free-carrier density were observed. A phenomenological impulse response model used...

  16. Open Automated Demand Response Dynamic Pricing Technologies and Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Ghatikar, Girish; Mathieu, Johanna L.; Piette, Mary Ann; Koch, Ed; Hennage, Dan

    2010-08-02

    This study examines the use of OpenADR communications specification, related data models, technologies, and strategies to send dynamic prices (e.g., real time prices and peak prices) and Time of Use (TOU) rates to commercial and industrial electricity customers. OpenADR v1.0 is a Web services-based flexible, open information model that has been used in California utilities' commercial automated demand response programs since 2007. We find that data models can be used to send real time prices. These same data models can also be used to support peak pricing and TOU rates. We present a data model that can accommodate all three types of rates. For demonstration purposes, the data models were generated from California Independent System Operator's real-time wholesale market prices, and a California utility's dynamic prices and TOU rates. Customers can respond to dynamic prices by either using the actual prices, or prices can be mapped into"operation modes," which can act as inputs to control systems. We present several different methods for mapping actual prices. Some of these methods were implemented in demonstration projects. The study results demonstrate show that OpenADR allows interoperability with existing/future systems/technologies and can be used within related dynamic pricing activities within Smart Grid.

  17. Dynamic anti-plane characteristic on an infinite piezoelectric medium with a movable rigid cylindrical inclusion

    Institute of Scientific and Technical Information of China (English)

    SONG Tian-shu; SUN Li-li; YU Zhen-dong

    2005-01-01

    Scattering and dynamic stress concentrations of time harmonic SH-wave in an infinite elastic piezoelectric medium with a movable rigid cylindrical inclusion are studied in this paper with the help of complex variable and wave function expansion method. The relations that a movable rigid cylindrical inclusion depends on intensity of incident wave and electric field are revealed. The expressions of dynamic stress at the edge of the inclusion are obtained. Numerical calculations are made with different wave numbers and different piezoelectric characteristic parameters. The calculating results show that dynamic stress concentrations at the edge of the inclusion have linear dependence on the incident electric field. And dynamic analyses are very important for an infinite piezoelectric medium with a movable rigid cylindrical inclusion at larger piezoelectric characteristic parameters.

  18. Research on rigid–flexible coupling dynamic characteristics of boom system in concrete pump truck

    Directory of Open Access Journals (Sweden)

    Hongbin Tang

    2015-03-01

    Full Text Available Concrete pump truck plays an important role in infrastructure construction and national economic development. In recent years, its boom system becomes longer, and its dynamic and control become more complicated. In order to study the dynamic characteristics of boom system, three dynamic models such as multi-rigid-body model, rigid–flexible coupling model, and rigid–flexible coupling model with equivalent hydraulic cylinder were built in this work. Simulation analysis and experimental analysis were done, and they show that we should not only consider the large-range motion but also consider the small flexible deformation to study the dynamic characteristics of boom system precisely. It provides the theoretical basis to vibration control, trajectory prediction, and life assessment for boom system and such structures.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhi-Wen [Department of Mechanics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China); Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control 92 Weijin Road, Nankai District, Tianjin 300072 (China); Zhang, Qing-Xin [Department of Mechanics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China); Xu, Jia, E-mail: xujia_ld@163.com [Department of Mechanics, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China)

    2014-11-03

    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.

  20. DYNAMIC CHARACTERISTIC ANALY- SIS OF PRECISE LONG STROKE LINEAR MOTOR WITH AIR-BEARING IN OPTICAL LITHOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    CHEN Xuedong; YU Xianzhong; HE Xueming; YAN Tianhong

    2008-01-01

    Dynamic characteristic is presented by identifying the model and the dynamic parameters of a precise long stroke linear motor (PLSLM) with the air-bearing in optical lithography. The PLSLM is supported by air-bearing on the stator, and is driven by on-board two large linear motors in a cross-configuration. Firstly, a model of the PLSLM is established by finite element method (FEM). Secondly, based on the model, the natural frequencies and model shapes are discussed. And the contribution of each active mode is evaluated by computing the modal participation factors (MPF), which indicates the major vibration direction. Furthermore, by the experimental modal analysis, the experimental results are in agreement with simulation results, which it is sure that the FEM is reasonable. What's more, comparing with the effects on the frequency due to the air-bearing stiffness, the relations of the natural frequencies with the air-bearing stiffness are found. It is found that the frequency response curve is fluctuant with the air-bearing stiffness in each direction. Finally, it is conclusion that the natural frequency of the PLSLM is largely affected by the air-bearing stiffness variety. This research is contributed to the dynamic characteristics resulted from the air-bearing stiffness. Further work will include better optimization on the dynamic parameter in the controller design through the control algorithm for the precise long stroke motor.

  1. [Response characteristics of neurons to tone in dorsal nucleus of the lateral lemniscus of the mouse].

    Science.gov (United States)

    Si, Wen-Juan; Cheng, Yan-Ling; Yang, Dan-Dan; Wang, Xin

    2016-02-25

    The dorsal nucleus of lateral lemniscus (DNLL) is a nucleus in the auditory ascending pathway, and casts inhibitory efferent projections to the inferior colliculus. Studies on the DNLL are less than studies on the auditory brain stem and inferior colliculus. To date, there is no information about response characteristics of neurons in DNLL of albino mouse. Under free field conditions, we used extracellular single unit recording to study the acoustic signal characteristics of DNLL neurons in Kunming mice (Mus musculus). Transient (36%) and ongoing (64%) firing patterns were found in 96 DNLL neurons. Neurons with different firing patterns have significant differences in characteristic frequency and minimal threshold. We recorded frequency tuning curves (FTCs) of 87 DNLL neurons. All of the FTCs exhibit an open "V" shape. There is no significant difference in FTCs between transient and ongoing neurons, but among the ongoing neurons, the FTCs of sustained neurons are sharper than those of onset plus sustained neurons and pauser neurons. Our results showed that the characteristic frequency of DNLL neurons of mice was not correlated with depth, supporting the view that the DNLL of mouse has no frequency topological organization through dorsal-ventral plane, which is different from cats and some other animals. Furthermore, by using rate-intensity function (RIF) analysis the mouse DNLL neurons can be classified as monotonic (60%), saturated (31%) and non-monotonic (8%) types. Each RIF type includes transient and ongoing firing patterns. Dynamic range of the transient firing pattern is smaller than that of ongoing firing ones (P transient firing pattern. Multiple firing patterns and intensity coding of DNLL neurons may derive from the projections from multiple auditory nuclei, and play different roles in auditory information processing.

  2. Test on dynamic characteristics of subgrade of heavy-haul railway in cold regions

    Institute of Scientific and Technical Information of China (English)

    YingYing Zhao; XianZhang Ling; ZiYu Wang; XinYan Shao; LiHui Tian; Lin Geng

    2015-01-01

    Dynamic characteristics of heavy-haul railway subgrade under vibratory loading in cold regions are investigated via low-temperature dynamic triaxial tests with multi-stage cyclic loading process. The relationship between dynamic shear stress and dynamic shear strain of frozen soil of subgrade under train loading and the influence of freezing temperatures on dynamic constitutive relation, dynamic shear modulus and damping ratio are observed in this study. Test results show that the dynamic constitutive relations of the frozen soils with different freezing temperatures comply with the hyperbolic model, in which model parameters a and b decrease with increasing freezing temperature. The dynamic shear modulus of the frozen soils decreases with increasing dynamic shear strains initially, followed by a relatively smooth attenuation tendency, whereas increases with decreasing freezing temperatures. The damping ratios decrease with decreasing freezing temperatures. Two linear functions are defined to express the linear relationships between dynamic shear modulus (damping ratio) and freezing temperature, respectively, in which corresponding linear coefficients are obtained through multiple regression analysis of test data.

  3. 创伤代谢反应及动力营养支持%Metabolic response and dynamic nutrition support after trauma

    Institute of Scientific and Technical Information of China (English)

    石汉平

    2013-01-01

    Trauma can induce a series of dynamic metabolic responses with different characteristics in three stages,including ebb phase,flow phase,and recovery phase.Nutrition support after trauma should be dynamically adjusted according to metabolic response and its individual phase,focusing on energy balance as well as metabolic modulation,adjusting immunological response to trauma by reduction of the exaggerated cytokines production,maintaining body protein balance,and enhancing wound healing.

  4. RESEARCH OF THE DYNAMIC CHARACTERISTICS ON A NEW HYDRAULIC SYSTEM OF ELECTRO-HYDRAULIC HAMMER

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new typed hydraulic system of electro-hydraulic hammer is researched and developed.By means of power bond graphs the modeling and simulation to the dynamic characteristics of the new hydraulic system are performed. The experimental research which is emphasized on the blowing stroke is also performed. It is proved from the result of simulation and experiment that this new hydraulic system possesses such advantages as simplification of structure,flexibleness of operation and reliability of working. Especially it possesses better dynamic characteristics.

  5. On the tribological characteristics of dynamically loaded journal bearing with micropolar fluids

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaoli; WANG; Kongying; ZHU; Keqin

    2004-01-01

    The addition of the additives to the lubricant oil to enhance the characteristics of the lubricant will influence the performance of the bearings. Based on the theory of micropolar fluids, the tribological characteristics of a dynamically-loaded journal bearing are numerically studied. Comparisons are made between the Newtonian fluids and the micropolar fluids. It is shown that for a dynamically-loaded journal bearing, the micropolar fluids yield an increase not only in the friction force, but also in the friction coefficient. In addition, the oil film pressure and the oil film thickness are obviously higher than that of Newtonian fluids.

  6. Dynamic response of wind turbine towers in warm permafrost

    Institute of Scientific and Technical Information of China (English)

    Benjamin Still; ZhaoHui Joey Yang; Simon Evans; FuJun Niu

    2014-01-01

    Wind is a great source of renewable energy in western Alaska. Consistent winds blow across the barren tundra underlain by warm permafrost in the winter season, when the energy demand is the highest. Foundation engineering in warm permafrost has always been a challenge in wind energy development. Degrading warm permafrost poses engineering issues to design, construction, and operation of wind turbines. This paper describes the foundation design of a wind turbine built in western Alaska. It presents a sys-tem for response monitoring and load assessment, and data collected from September 2013 to March 2014. The dynamic proper-ties are assessed based on the monitoring data, and seasonal changes in the dynamic properties of the turbine tower-foundation system and likely resonance between the spinning blades and the tower structure are discussed. These analyses of a wind turbine in warm permafrost are valuable for designing or retrofitting of foundations in warm permafrost.

  7. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers.

    Science.gov (United States)

    Xu, Lai; Li, Youyong

    2016-06-30

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers.

  8. Experimental research on dynamic operating characteristics of a novel silica gel-water adsorption chiller

    Institute of Scientific and Technical Information of China (English)

    WANG Dechang; WU Jingyi; WANG Ruzhu; DOU Weidong

    2007-01-01

    A novel silica gel-water adsorption chiller consisting of two adsorption/desorption chambers and an evaporator with one heat-pipe working chamber is experimentally studied.The dynamic operating characteristics of the chiller and the thermodynamic characteristics of the adsorber are obtained.The experimental results show that the dynamic operating characteristics of the chiller and the thermodynamic characteristics of the adsorber are satisfactory and that the cycle is a novel and effective adsorption cycle.A mass recovery process increases the cyclic adsorption capacity of the system and improves adaptability of the chiller to a lowgrade heat source.In addition,the experiment indicates that this novel chiller is highly suitable for an air conditioning system with a low dehumidification requirement or a system with a large cycle flowrate and an industrial cooling water system.

  9. Phase response curves for models of earthquake fault dynamics

    CERN Document Server

    Franović, Igor; Perc, Matjaz; Klinshov, Vladimir; Nekorkin, Vladimir; Kurths, Jürgen

    2016-01-01

    We systematically study effects of external perturbations on models describing earthquake fault dynamics. The latter are based on the framework of the Burridge-Knopoff spring-block system, including the cases of a simple mono-block fault, as well as the paradigmatic complex faults made up of two identical or distinct blocks. The blocks exhibit relaxation oscillations, which are representative for the stick-slip behavior typical for earthquake dynamics. Our analysis is carried out by determining the phase response curves of first and second order. For a mono-block fault, we consider the impact of a single and two successive pulse perturbations, further demonstrating how the profile of phase response curves depends on the fault parameters. For a homogeneous two-block fault, our focus is on the scenario where each of the blocks is influenced by a single pulse, whereas for heterogeneous faults, we analyze how the response of the system depends on whether the stimulus is applied to the block having a shorter or a ...

  10. Phase response curves for models of earthquake fault dynamics

    Science.gov (United States)

    Franović, Igor; Kostić, Srdjan; Perc, Matjaž; Klinshov, Vladimir; Nekorkin, Vladimir; Kurths, Jürgen

    2016-06-01

    We systematically study effects of external perturbations on models describing earthquake fault dynamics. The latter are based on the framework of the Burridge-Knopoff spring-block system, including the cases of a simple mono-block fault, as well as the paradigmatic complex faults made up of two identical or distinct blocks. The blocks exhibit relaxation oscillations, which are representative for the stick-slip behavior typical for earthquake dynamics. Our analysis is carried out by determining the phase response curves of first and second order. For a mono-block fault, we consider the impact of a single and two successive pulse perturbations, further demonstrating how the profile of phase response curves depends on the fault parameters. For a homogeneous two-block fault, our focus is on the scenario where each of the blocks is influenced by a single pulse, whereas for heterogeneous faults, we analyze how the response of the system depends on whether the stimulus is applied to the block having a shorter or a longer oscillation period.

  11. Automated Dynamic Demand Response Implementation on a Micro-grid

    Energy Technology Data Exchange (ETDEWEB)

    Kuppannagari, Sanmukh R.; Kannan, Rajgopal; Chelmis, Charalampos; Prasanna, Viktor K.

    2016-11-16

    In this paper, we describe a system for real-time automated Dynamic and Sustainable Demand Response with sparse data consumption prediction implemented on the University of Southern California campus microgrid. Supply side approaches to resolving energy supply-load imbalance do not work at high levels of renewable energy penetration. Dynamic Demand Response (D2R) is a widely used demand-side technique to dynamically adjust electricity consumption during peak load periods. Our D2R system consists of accurate machine learning based energy consumption forecasting models that work with sparse data coupled with fast and sustainable load curtailment optimization algorithms that provide the ability to dynamically adapt to changing supply-load imbalances in near real-time. Our Sustainable DR (SDR) algorithms attempt to distribute customer curtailment evenly across sub-intervals during a DR event and avoid expensive demand peaks during a few sub-intervals. It also ensures that each customer is penalized fairly in order to achieve the targeted curtailment. We develop near linear-time constant-factor approximation algorithms along with Polynomial Time Approximation Schemes (PTAS) for SDR curtailment that minimizes the curtailment error defined as the difference between the target and achieved curtailment values. Our SDR curtailment problem is formulated as an Integer Linear Program that optimally matches customers to curtailment strategies during a DR event while also explicitly accounting for customer strategy switching overhead as a constraint. We demonstrate the results of our D2R system using real data from experiments performed on the USC smartgrid and show that 1) our prediction algorithms can very accurately predict energy consumption even with noisy or missing data and 2) our curtailment algorithms deliver DR with extremely low curtailment errors in the 0.01-0.05 kWh range.

  12. Characteristics, Responsibilities, and Qualities of Urban School Mentors.

    Science.gov (United States)

    Guyton, Edith; Hidalgo, Francisco

    1995-01-01

    Teacher mentors in urban schools need particular characteristics to promote development in beginning teachers because the urban school is a unique environment. Urban mentor teachers need to be able to articulate their beliefs and practices, and they need well-developed coaching skills. (SLD)

  13. Characteristics, Responsibilities, and Qualities of Urban School Mentors.

    Science.gov (United States)

    Guyton, Edith; Hidalgo, Francisco

    1995-01-01

    Teacher mentors in urban schools need particular characteristics to promote development in beginning teachers because the urban school is a unique environment. Urban mentor teachers need to be able to articulate their beliefs and practices, and they need well-developed coaching skills. (SLD)

  14. Characteristics of response factors of coaxial gaseous rocket injectors

    Science.gov (United States)

    Janardan, B. A.; Daniel, B. R.; Zinn, B. T.

    1975-01-01

    The results of an experimental investigation undertaken to determine the frequency dependence of the response factors of various gaseous propellant rocket injectors subject to axial instabilities are presented. The injector response factors were determined, using the modified impedance-tube technique, under cold-flow conditions simulating those observed in unstable rocket motors. The tested injectors included a gaseous-fuel injector element, a gaseous-oxidizer injector element and a coaxial injector with both fuel and oxidizer elements. Emphasis was given to the determination of the dependence of the injector response factor upon the open-area ratio of the injector, the length of the injector orifice, and the pressure drop across the injector orifices. The measured data are shown to be in reasonable agreement with the corresponding injector response factor data predicted by the Feiler and Heidmann model.

  15. Experiment study of dynamics response for wind turbine system of floating foundation

    Science.gov (United States)

    Tang, You-gang; Song, Kai; Wang, Bin

    2015-12-01

    The floating foundation is designed to support a 1.5 MW wind turbine in 30 m water depth. With consideration of the viscous damping of foundation and heave plates, the amplitude-frequency response characteristics of the foundation are studied. By taking into account the elastic effect of blades and tower, the classic quasi-steady blade-element/momentum (BEM) theory is used to calculate the aerodynamic elastic loads. A coupled dynamic model of the turbine-foundationmooring lines is established to calculate the motion response of floating foundation under Kaimal wind spectrum and regular wave by using the FAST codes. The model experiment is carried out to test damping characteristics and natural motion behaviors of the wind turbine system. The dynamics response is tested by considering only waves and the joint action of wind and waves. It is shown that the wind turbine system can avoid resonances under the action of wind and waves. In addition, the heave motion of the floating foundation is induced by waves and the surge motion is induced by wind. The action of wind and waves is of significance for pitch.

  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. The dynamic response of carbon fiber-filled polymer composites

    OpenAIRE

    Patterson B.; Orler E.B.; Furmanski J.; Rigg P.A.; Scharff R.J.; Stahl D.B.; Sheffield S.A.; Gustavsen R.L.; Dattelbaum D.M.; Coe J.D.

    2012-01-01

    The dynamic (shock) responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little-to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE) composite to 18.6 GPa in the through-thickness direction,...

  18. Dynamic Response of a Chevron Concentrically Braced Frame

    OpenAIRE

    Okazaki, Taichiro; Lignos, Dimitrios G.; Hikino, Tsuyoshi; Kajiwara, Koichi

    2013-01-01

    Large-scale shake table tests were conducted at E-Defense, Japan, to examine the dynamic response of a steel concentrically braced frame. The specimen was a single-bay, single-story frame with a pair of square hollow structural section braces placed in a chevron arrangement. The gusset plates connecting the brace to the framing elements were provided with an elliptic fold line to accommodate out-of-plane rotation of the brace in compression. The specimen was subjected repeatedly to a unidirec...

  19. Frequency characteristic of response of surface air pressure to changes in flux of cosmic rays

    Science.gov (United States)

    Bogdanov, M. B.

    2014-11-01

    We compare the series of daily-average values of the surface air pressure for De Bilt and Lugano meteorological stations with subtracted linear trends and seasonal harmonics, as well as the series of the flux of galactic cosmic rays (GCRs) at Jungfraujoch station with subtracted moving average over 200 days. Using the method of superposed epochs, we show that the Forbush decreases at both stations are accompanied by increased pressure. Spectral analysis allows us to conclude that the analyzed series are characterized by nonzero coherence in almost the entire frequency range: from 0.02 day-1 day up to the Nyquist frequency of 0.5 day-1. Using changes in the GCR flux as a probing signal, we obtain amplitude-frequency characteristics of the pressure reaction. For both stations, these characteristics are in qualitative agreement with each other and indicate that the atmospheric response can be described by a second-order linear dynamic system that has wide resonance with a maximum at a frequency of 0.15 day-1.

  20. Immunological dynamics in response to two anthrax vaccines in mice

    Institute of Scientific and Technical Information of China (English)

    L(U) Jin; HE Rui; DONG Mei; ZHANG LiangYan; WANG XiLiang

    2008-01-01

    In order to understand the variation of humoral and cellular immune responses to A16R live spore and AVA vaccine and to identify efficient immunological parameters for the early evaluation of post immu-nization in mice, we dynamically monitored the antibody production and cellular responses after the vaccination of Balb/C mice with the anthrax vaccines. The results show that both anti-AVA and anti-Spore antibodies were detectable in the A16R live spore vaccinated group while high titers of anti-AVA antibodies but not anti-Spore antibodies existed in the AVA-immunized group, IgG1 and IgG2 were the major subtypes of IgG in both of the two groups. However, the IgG2a level was significantly higher in the A16R group than in the AVA group. At the cellular level, responses of antigen-specific TH2, TH1 and plasma cells were detected. The peripheral TH2 responses could be seen on day 5 after vac-cination, and remained at a high level throughout the experiment (from day 5 post primary immuniza-tion to day 60 post the tertiary immunization); the TH1 responses to A16R vaccine appeared on day 5, while the responses to AVA could only be detected by day 7 after the secondary immunization; a low level of TH1 responses could be observed at the end of the experiment. Antigen-specific plasma cells could be found in the peripheral blood of both the immunized groups, however, the responses in the A16R group appeared earlier, lasted longer, and shown an ascending tendency until the end of the ex-periment when the plasma cell responses in the AVA group were reduced to a very low level. The re-sults suggest that the multiple antigen containing A16R live spore vaccine induces better immune re-sponses than AVA. Combined with serum antibody titers, TH2, TH1 and plasma cell responses could be used as immunological parameters for the evaluation of vaccine efficacy, These findings may afford new insight into the early evaluation of vaccination as well as being a powerful strategy for vaccine

  1. Coupled dynamic response analysis of a multi-column tension-leg-type floating wind turbine

    Science.gov (United States)

    Zhao, Yong-sheng; Yang, Jian-min; He, Yan-ping; Gu, Min-tong

    2016-07-01

    This paper presents a coupled dynamic response analysis of a multi-column tension-leg-type floating wind turbine (WindStar TLP system) under normal operation and parked conditions. Wind-only load cases, wave-only load cases and combined wind and wave load cases were analyzed separately for the WindStar TLP system to identify the dominant excitation loads. Comparisons between an NREL offshore 5-MW baseline wind turbine installed on land and the WindStar TLP system were performed. Statistics of selected response variables in specified design load cases (DLCs) were obtained and analyzed. It is found that the proposed WindStar TLP system has small dynamic responses to environmental loads and it thus has almost the same mean generator power output under operating conditions as the land-based system. The tension mooring system has a sufficient safety factor, and the minimum tendon tension is always positive in all selected DLCs. The ratio of ultimate load of the tower base fore-aft bending moment for the WindStar TLP system versus the land-based system can be as high as 1.9 in all of the DLCs considered. These results will help elucidate the dynamic characteristics of the proposed WindStar TLP system, identify the difference in load effect between it and land-based systems, and thus make relevant modifications to the initial design for the WindStar TLP system.

  2. Polymerization Parameters Influencing the QCM Response Characteristics of BSA MIP

    Directory of Open Access Journals (Sweden)

    Nam V. H. Phan

    2014-06-01

    Full Text Available Designing Molecularly Imprinted Polymers for sensing proteins is still a somewhat empirical process due to the inherent complexity of protein imprinting. Based on Bovine Serum Albumin as a model analyte, we explored the influence of a range of experimental parameters on the final sensor responses. The optimized polymer contains 70% cross linker. Lower amounts lead to higher sensitivity, but also sensor response times substantially increase (to up to 10 h at constant imprinting effect (signal ratio MIP/NIP on quartz crystal microbalance—QCM. However, by shifting the polymer properties to more hydrophilic by replacing methacrylic acid by acrylic acid, part of the decreased sensitivity can be recovered leading to appreciable sensor responses. Changing polymer morphology by bulk imprinting and nanoparticle approaches has much lower influence on sensitivity.

  3. Vascularized composite allograft-specific characteristics of immune responses.

    Science.gov (United States)

    Issa, Fadi

    2016-06-01

    Vascularized composite allograft (VCA) transplantation, or reconstructive transplantation, has revolutionized the treatment of complex tissue and functional defects. Despite arriving during an age in which the immunology of solid organ transplant rejection has been investigated in much detail, these transplants have offered new perspectives from which to explore the immunobiology of transplantation. VCAs have a number of unique molecular, cellular, and architectural features which alter the character and intensity of the rejection response. While much is yet to be clarified, an understanding of these distinct mechanisms affords new possibilities for the control of immune responses in an effort to improve outcomes after VCA transplantation.

  4. Immunological dynamics in response to two anthrax vaccines in mice

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to understand the variation of humoral and cellular immune responses to A16R live spore and AVA vaccine and to identify efficient immunological parameters for the early evaluation of post immu- nization in mice, we dynamically monitored the antibody production and cellular responses after the vaccination of Balb/C mice with the anthrax vaccines. The results show that both anti-AVA and anti-Spore antibodies were detectable in the A16R live spore vaccinated group while high titers of anti-AVA antibodies but not anti-Spore antibodies existed in the AVA-immunized group. IgG1 and IgG2 were the major subtypes of IgG in both of the two groups. However, the IgG2a level was significantly higher in the A16R group than in the AVA group. At the cellular level, responses of antigen-specific TH2, TH1 and plasma cells were detected. The peripheral TH2 responses could be seen on day 5 after vac- cination, and remained at a high level throughout the experiment (from day 5 post primary immuniza- tion to day 60 post the tertiary immunization); the TH1 responses to A16R vaccine appeared on day 5, while the responses to AVA could only be detected by day 7 after the secondary immunization; a low level of TH1 responses could be observed at the end of the experiment. Antigen-specific plasma cells could be found in the peripheral blood of both the immunized groups, however, the responses in the A16R group appeared earlier, lasted longer, and shown an ascending tendency until the end of the ex- periment when the plasma cell responses in the AVA group were reduced to a very low level. The re- sults suggest that the multiple antigen containing A16R live spore vaccine induces better immune re- sponses than AVA. Combined with serum antibody titers, TH2, TH1 and plasma cell responses could be used as immunological parameters for the evaluation of vaccine efficacy. These findings may afford new insight into the early evaluation of vaccination as well as being a powerful strategy for

  5. Dynamic Characteristics of the Herringbone Groove Gas Journal Bearings: Numerical Simulations

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2016-01-01

    Full Text Available Dynamic characteristics of the herringbone grooved gas journal bearings (HGGJB under fluid-structure interactions are systematically investigated using the finite element method. Stability and bearing capacity of the HGGJB are estimated and compared with those of the plain gas journal bearings (PGJB. Influences of the structural parameters, including the spiral angle, the groove number, the groove depth, the pressure relief hole diameter, the bearing radial clearance, the length to diameter ratio, and the rotating speed, on dynamic characteristics of HGGJB are analyzed. To verify the numerical simulation results, pressure nephograms and cross-section pressure curves of the same rotor model, calculated by the numerical simulation and the theoretical method, respectively, are compared. Similar results are obtained. Compared to the common constrained boundary conditions in the previous numerical simulations, boundary conditions adopted in this paper are complete self-absorption and the change of the gas inlet and outlet depends on the rotating state of the rotor, which are more accordant with the real dynamic characteristics of the HGGJB. In all, the results presented in this paper provide a deeper and better understanding of the dynamic characteristics of the HGGJB under fluid-structure interactions.

  6. Static and dynamic characteristics of angular velocity and acceleration transducers based on optical tunneling effect

    Science.gov (United States)

    Busurin, V. I.; Korobkov, V. V.; Htoo Lwin, Naing; Tuan, Phan Anh

    2016-08-01

    Theoretical and experimental analysis of quasi-linear conversion function of angular velocity and acceleration microoptoelectromechnical (MOEM) transducers based on optical tunneling effect (OTE) are conducted. Equivalent oscillating circuit is developed and dynamic characteristics of angular velocity and acceleration MOEM-transducers are investigated.

  7. 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, indi

  8. Dynamic characteristics of the steam condensation due to a multi-hole sparger

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiangbin [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy (China); Li, Nan [Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy (China); Zhang, Mengchao [China Power Engineering Consulting (Group) Investment Co. LTD, Beijing (China)

    2016-06-15

    In order to deeply understand the mechanism of the steam jet with a multi-hole sparger, the dynamic characteristics of direct contact condensation of the steam submerged in a subcooled water pool are simulated by means of commercial software. The jet shapes are compared with experimental results. It is found that the numerical results were in good agreement with the experimental ones.

  9. A benchmark test of accuracy and precision in estimating dynamical systems characteristics from a time series

    NARCIS (Netherlands)

    Rispens, S.M.; Pijnappels, M.A.G.M.; Dieen, van J.H.; Schooten, van K.S.; Beek, P.J.; Daffertshofer, A.

    2014-01-01

    Characteristics of dynamical systems are often estimated to describe physiological processes. For instance, Lyapunov exponents have been determined to assess the stability of the cardio-vascular system, respiration, and, more recently, human gait and posture. However, the systematic evaluation of

  10. Novel method for estimating the dynamic characteristics of pressure sensor in shock tube calibration test.

    Science.gov (United States)

    Li, Qiang; Wang, Zhongyu; Wang, Zhuoran; Yan, Hu

    2015-06-01

    A shock tube is usually used to excite the dynamic characteristics of the pressure sensor used in an aircraft. This paper proposes a novel estimation method for determining the dynamic characteristic parameters of the pressure sensor. A preprocessing operation based on Grey Model [GM(1,1)] and bootstrap method (BM) is employed to analyze the output of a calibrated pressure sensor under step excitation. Three sequences, which include the estimated value sequence, upper boundary, and lower boundary, are obtained. The processing methods on filtering and modeling are used to explore the three sequences independently. The optimal estimated, upper boundary, and lower boundary models are then established. The three models are solved, and a group of dynamic characteristic parameters corresponding to the estimated intervals are obtained. A shock tube calibration test consisting of two experiments is performed to validate the performance of the proposed method. The results show that the relative errors of the dynamic characteristic parameters of time and frequency domains do not exceed 9% and 10%, respectively. Moreover, the nominal and estimated values of the parameters fall into the estimated intervals limited by the upper and lower values.

  11. Ditching Investigations of Dynamic Models and Effects of Design Parameters on Ditching Characteristics

    Science.gov (United States)

    Fisher, Lloyd J; Hoffman, Edward L

    1958-01-01

    Data from ditching investigations conducted at the Langley Aeronautical Laboratory with dynamic scale models of various airplanes are presented in the form of tables. The effects of design parameters on the ditching characteristics of airplanes, based on scale-model investigations and on reports of full-scale ditchings, are discussed. Various ditching aids are also discussed as a means of improving ditching behavior.

  12. On the dynamics of the characteristic curves for the LSW model

    Directory of Open Access Journals (Sweden)

    Juan J. L. Velazquez

    2006-04-01

    Full Text Available This paper describes in a rigorous manner how the dynamics of the characteristic curves for the Lifshitz-Slyozov-Wagner (LSW model of coarsening transforms a class of noncompactly supported initial data in functions that behave in a self-similar manner for long times.

  13. Dynamic response of fiber bundle under transverse impact.

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei-Yang; Song, Bo

    2010-03-01

    There has been a very high demand in developing efficient soft body armors to protect the military and law enforcement personnel from ballistic or explosive attack. As a basic component in the soft body armor, fibers or fiber bundles play a key role in the performance against ballistic impact. In order to study the ballistic-resistant mechanism of the soft body armor, it is desirable to understand the dynamic response of the fiber bundle under transverse impact. Transverse wave speed is one important parameter because a faster transverse wave speed can make the impact energy dissipate more quickly. In this study, we employed split Hopkinson pressure bar (SHPB) to generate constant high-speed impact on a Kevlar fiber bundle in the transverse direction. The deformation of the fiber bundle was photographed with high-speed digital cameras. The transverse wave speeds were experimentally measured at various transverse impact velocities. The experimental results can also be used to quantitatively verify the current analytical models or to develop new models to describe the dynamic response of fiber bundle under transverse impact.

  14. Dynamism of Stimuli-Responsive Nanohybrids: Environmental Implications

    Directory of Open Access Journals (Sweden)

    Jaime Plazas-Tuttle

    2015-06-01

    Full Text Available Nanomaterial science and design have shifted from generating single passive nanoparticles to more complex and adaptive multi-component nanohybrids. These adaptive nanohybrids (ANHs are designed to simultaneously perform multiple functions, while actively responding to the surrounding environment. ANHs are engineered for use as drug delivery carriers, in tissue-engineered templates and scaffolds, adaptive clothing, smart surface coatings, electrical switches and in platforms for diversified functional applications. Such ANHs are composed of carbonaceous, metallic or polymeric materials with stimuli-responsive soft-layer coatings that enable them to perform such switchable functions. Since ANHs are engineered to dynamically transform under different exposure environments, evaluating their environmental behavior will likely require new approaches. Literature on polymer science has established a knowledge core on stimuli-responsive materials. However, translation of such knowledge to environmental health and safety (EHS of these ANHs has not yet been realized. It is critical to investigate and categorize the potential hazards of ANHs, because exposure in an unintended or shifting environment could present uncertainty in EHS. This article presents a perspective on EHS evaluation of ANHs, proposes a principle to facilitate their identification for environmental evaluation, outlines a stimuli-based classification for ANHs and discusses emerging properties and dynamic aspects for systematic EHS evaluation.

  15. Dynamics of telomerase activity in response to acute psychological stress

    Science.gov (United States)

    Epel, Elissa S.; Lin, Jue; Dhabhar, Firdaus S.; Wolkowitz, Owen M.; Puterman, E; Karan, Lori; Blackburn, Elizabeth H.

    2010-01-01

    Telomerase activity plays an essential role in cel0l survival, by lengthening telomeres and promoting cell growth and longevity. It is now possible to quantify the low levels of telomerase activity in human leukocytes. Low basal telomerase activity has been related to chronic stress in people and to chronic glucocorticoid exposure in vitro. Here we test whether leukocyte telomerase activity changes under acute psychological stress. We exposed 44 elderly women, including 22 high stress dementia caregivers and 22 matched low stress controls, to a brief laboratory psychological stressor, while examining changes in telomerase activity of peripheral blood mononuclear cells (PBMC). At baseline, caregivers had lower telomerase activity levels than controls, but during stress telomerase activity increased similarly in both groups. Across the entire sample, subsequent telomerase activity increased by 18% one hour after the end of the stressor (p<0.01). The increase in telomerase activity was independent of changes in numbers or percentages of monocytes, lymphocytes, and specific T cell types, although we cannot fully rule out some potential contribution from immune cell redistribution in the change in telomerase activity. Telomerase activity increases were associated with greater cortisol increases in response to the stressor. Lastly, psychological response to the tasks (greater threat perception) was also related to greater telomerase activity increases in controls. These findings uncover novel relationships of dynamic telomerase activity with exposure to an acute stressor, and with two classic aspects of the stress response -- perceived psychological stress and neuroendocrine (cortisol) responses to the stressor. PMID:20018236

  16. The dynamic range of response set activation during action sequencing.

    Science.gov (United States)

    Behmer, Lawrence P; Crump, Matthew J C

    2017-03-01

    We show that theories of response scheduling for sequential action can be discriminated on the basis of their predictions for the dynamic range of response set activation during sequencing, which refers to the momentary span of activation states for completed and to-be-completed actions in a response set. In particular, theories allow that future actions in a plan are partially activated, but differ with respect to the width of the range, which refers to the number of future actions that are partially activated. Similarly, theories differ on the width of the range for recently completed actions that are assumed to be rapidly deactivated or gradually deactivated in a passive fashion. We validate a new typing task for measuring momentary activation states of actions across a response set during action sequencing. Typists recruited from Amazon Mechanical Turk copied a paragraph by responding to a "go" signal that usually cued the next letter but sometimes cued a near-past or future letter (n-3, -2, -1, 0, +2, +3). The activation states for producing letters across go-signal positions can be inferred from RTs and errors. In general, we found evidence of graded parallel activation for future actions and rapid deactivation of more distal past actions. (PsycINFO Database Record

  17. Input-response relationships in the dynamics of glycolysis.

    Science.gov (United States)

    Markus, M; Hess, B

    1985-12-01

    The dynamic response of glycolysis is investigated using a two-enzyme model with three different type of input flux time dependences: constant, sinusoidal, and amplitude or frequency modulated (AM or FM) input flux. The analysis reveals that the system acts as a device which transduces amplitudes and frequencies of the input function into complex and remarkably diverse response patterns. This device may have more than one response possibilities for a single input function, owing to the coexistence of attractors in phase space. In such a case one response function can be switched over into the other by short substrate pulses. Stroboscopic plots reveal that chaotic regimes obtained under sinusoidal input flux obey a stretch-fold-press process, similar to the baker's transformation, upon a change of the stroboscoping phase. Chaotic oscillations obtained under AM or FM conditions often show a much higher degree of randomness than those obtained under sinusoidal input. This is expressed quantitatively by an enhanced Liapunov dimension of the attractors.

  18. Temporal characteristics of gustatory responses in rat parabrachial neurons vary by stimulus and chemosensitive neuron type.

    Science.gov (United States)

    Geran, Laura; Travers, Susan

    2013-01-01

    It has been demonstrated that temporal features of spike trains can increase the amount of information available for gustatory processing. However, the nature of these temporal characteristics and their relationship to different taste qualities and neuron types are not well-defined. The present study analyzed the time course of taste responses from parabrachial (PBN) neurons elicited by multiple applications of "sweet" (sucrose), "salty" (NaCl), "sour" (citric acid), and "bitter" (quinine and cycloheximide) stimuli in an acute preparation. Time course varied significantly by taste stimulus and best-stimulus classification. Across neurons, the ensemble code for the three electrolytes was similar initially but quinine diverged from NaCl and acid during the second 500 ms of stimulation and all four qualities became distinct just after 1s. This temporal evolution was reflected in significantly broader tuning during the initial response. Metric space analyses of quality discrimination by individual neurons showed that increases in information (H) afforded by temporal factors was usually explained by differences in rate envelope, which had a greater impact during the initial 2s (22.5% increase in H) compared to the later response (9.5%). Moreover, timing had a differential impact according to cell type, with between-quality discrimination in neurons activated maximally by NaCl or citric acid most affected. Timing was also found to dramatically improve within-quality discrimination (80% increase in H) in neurons that responded optimally to bitter stimuli (B-best). Spikes from B-best neurons were also more likely to occur in bursts. These findings suggest that among PBN taste neurons, time-dependent increases in mutual information can arise from stimulus- and neuron-specific differences in response envelope during the initial dynamic period. A stable rate code predominates in later epochs.

  19. 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.

  20. Interfacial characteristics and dynamic mechanical properties of Wf/Zr-based metallic glass matrix composites

    Institute of Scientific and Technical Information of China (English)

    MA Wei-feng; KOU Hong-chao; CHEN Chun-sheng; LI Jin-shan; HU Rui; XING Li-qian; ZHOU Lian; FU Heng-zhi

    2008-01-01

    Tungsten fiber reinforced Zr41.25Ti13.75Cu12.5Ni10Be22.5 metallic glass matrix composites were fabricated by means of melt infiltration casting. Their dynamic compressive tests were performed using a Hopkinson bar. The relationship between the interfacial characteristics and the dynamic compressive behavior was investigated. The results indicate that the interface characteristics of composites include interfacial diffusion and interfacial reaction, and the interfacial shear strength increases when the interfacial reaction is serious. The dynamic plastic performance are improved obviously if the suitable interface reaction occurs. The failure occurs by shear and the fibers split longitudinally if there is no interface reaction or a little reaction; in contrast, holistic failure occurs if there is too much interface reaction.

  1. Small scale experimental study of the dynamic response of a tension leg platform wind turbine

    DEFF Research Database (Denmark)

    Hansen, Anders Mandrup; Laugesen, Robert; Bredmose, Henrik

    2014-01-01

    A floating Tension Leg Platform (TLP) wind turbine was constructed at scale 1/200 and its dynamic response was analysed experimentally in co-directional wind and waves. The wind turbine was Froude scaled and a new rotor was designed to yield maximum power and Froude scaled thrust at the low model...... Reynolds number. Physical limitations due to the large scaling ratio further meant that some structural adjustments were necessary. Nacelle and floater accelerations were measured by means of two accelerometers. The TLP was moored with four different tendon configurations and exposed to different constant...... increases the occurrence of slack tendons and the magnitude of the pitch accelerations. In a robust commercial design, however, slack tendons must be avoided. The experiments demonstrate the ability of the wind turbine model and the experimental setup to give insight to the dynamic characteristics...

  2. Temporal and spatial dynamical simulation of groundwater characteristics in Minqin Oasis

    Institute of Scientific and Technical Information of China (English)

    XIAO DuNing; LI XiaoYu; SONG DongMei; YANG GuoJing

    2007-01-01

    Application scope of geostatistics has been gradually extended from original geologic field to soil science and ecological field, etc. And its successful application results have been widely demonstrated. But little information is reported as to the direct use of geostatistical method to work out the distribution map of groundwater characteristics. In this paper the semivariogram of geostatistics, in combination with GIS, was used to quantitatively study the spatial variation characteristics of groundwater table depth and mineralization degree and their relation to the landuse changes. F test of the used spherical model reached a very significant level, and the theoretical model can well reflect the spatial structural characteristics of groundwater table depth and mineralization degree and achieve an ideal result. This shows that the application of the method in the dynamical simulation of groundwater is feasible. And this paper also provides useful reference for the application of geostatistics in the study of the dynamical variations of groundwater resources in the oasis.

  3. Nonlinear Dynamic Characteristic Analysis of the Shaft System in Water Turbine Generator Set

    Institute of Scientific and Technical Information of China (English)

    MA Zhenyue; SONG Zhiqiang

    2009-01-01

    A 3D finite element vibration model of water turbine generator set is constructed considering the coupling with hydropower house foundation. The method of determining guide bearing dynamic characteristic coefficients according to the swing of the shaft is proposed, which can be used for studying the self-vibration characteristic and stability of the water turbine generator set. The method fully considers the complex supporting boundary and loading conditions; especially the nonlinear variation of guide bearing dynamic characteristic coefficients and the coupling effect of the whole power-house foundation. The swing and critical rotating speed of an actual generator set shaft system are calculated. The simulated results of the generator set indicate that the coupling vibration model and calculation method presented in this paper are suitable for stability analysis of the water turbine generator set.

  4. 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.

  5. The Influence of Earth Temperature on the Dynamic Characteristics of Frozen Soil and the Parameters of Ground Motion on Sites of Permafrost

    Institute of Scientific and Technical Information of China (English)

    Wang Lanmin; Zhang Dongli; Wu Zhijian; Ma Wei; Li Xiaojun

    2004-01-01

    Earth temperature is one of the most important factors influencing the mechanical properties of frozen soil. Based on the field investigation of the characteristics of ground deformation and ground failure caused by the Ms8.1 earthquake in the west of the Kuniun Mountain Pass,China, the influence of temperature on the dynamic constitutive relationship, dynamic elastic modulus, damping ratio and dynamic strength of frozen soil was quantitatively studied by means of the dynamic triaxial test. Moreover, the characteristics of ground motion on a permafrost site under different temperatures were analyzed for the four profiles of permafrost along the Qinghai-Xizang (Tibet) Railway using the time histories of ground motion acceleration with 3 exceedance probabilities of the Kunlun Mountains area. The influences of temperature on the seismic displacement, velocity, acceleration and response spectrum on permafrost ground were studied quantitatively. A scientific basis was presented for earthquake disaster mitigation for engineering foundations, highways and underground engineering in permafrost areas.

  6. Dynamics of electromagnetic slip coupling for hydraulic power steering application and its energy-saving characteristics

    Institute of Scientific and Technical Information of China (English)

    TANG Bin; JIANG Hao-bin; XU Zhe; GENG Guo-qing; XU Xing

    2015-01-01

    To improve high-speed road feel and enhance energetic efficiency of hydraulic power steering (HPS) system in heavy-duty vehicles, an electromagnetic slip coupling (ESC) was applied to the steering system, which regulated discharge flow of steering pump to realize variable assist characteristic as well as uniquely transfer on-demand power from engine to steering pump. The model of ESC was established and the dynamic characteristics of ESC were presented by the way of simulation and experiment. Upon the layout of the assist characteristics, output torque of ESC was derived. Based on the ESC model, the output torque characteristics of ESC were simulated under steering situation and straight driving situation, respectively. The consistency of simulated ESC output torque and the one deduced from assist characteristics verifies the correctness of the ESC dynamic model. To illustrate energy saving characteristics of ESC-HPS, energy consumption comparison of ESC-HPS and conventional HPS was carried out qualitatively and quantitatively. It follows that the energy consumption of ESC-HPS decreases by 50% compared with that of HPS.

  7. New literal approximations for the longitudinal dynamic characteristics of flexible flight vehicles

    Science.gov (United States)

    Livneh, Rafael; Schmidt, David K.

    1992-01-01

    The goal of the literal approximation method is to obtain simple literal (analytical) approximations for key dynamic characteristics of flexible flight vehicles. A basic question regarding the method is its usefulness as an additional design tool for existing design and simulation procedures. Two aspects of this question are: (1) ease of derivation and use of the literal approximations, and (2) the suitability of one set of literal approximations to describe the dynamics of a large set of significantly different vehicles. These issues are addressed by incorporating symbolic manipulation software into the literal approximation method for the analysis of a fifth order model of the longitudinal dynamics of a flexible flight vehicle. The automated literal approximation generated in this fashion reduces the manual derivation time by an approximate factor of four. A single set of literal approximations is shown to provide adequate approximations for the dynamics of significantly different flight vehicles configurations, such as an aircraft, a missile, and a hypersonic vehicle.

  8. 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.

  9. Dynamic Response of Linear Mechanical Systems Modeling, Analysis and Simulation

    CERN Document Server

    Angeles, Jorge

    2012-01-01

    Dynamic Response of Linear Mechanical Systems: Modeling, Analysis and Simulation can be utilized for a variety of courses, including junior and senior-level vibration and linear mechanical analysis courses. The author connects, by means of a rigorous, yet intuitive approach, the theory of vibration with the more general theory of systems. The book features: A seven-step modeling technique that helps structure the rather unstructured process of mechanical-system modeling A system-theoretic approach to deriving the time response of the linear mathematical models of mechanical systems The modal analysis and the time response of two-degree-of-freedom systems—the first step on the long way to the more elaborate study of multi-degree-of-freedom systems—using the Mohr circle Simple, yet powerful simulation algorithms that exploit the linearity of the system for both single- and multi-degree-of-freedom systems Examples and exercises that rely on modern computational toolboxes for both numerical and symbolic compu...

  10. Polarized actin structural dynamics in response to cyclic uniaxial stretch

    Science.gov (United States)

    Huang, Lawrence; Helmke, Brian P.

    2014-01-01

    Endothelial cell (EC) alignment to directional flow or stretch supports anti-inflammatory functions, but mechanisms controlling polarized structural adaptation in response to physical cues remain unclear. This study aimed to determine whether factors associated with early actin edge ruffling implicated in cell polarization are prerequisite for stress fiber (SF) reorientation in response to cyclic uniaxial stretch. Time-lapse analysis of EGFP-actin in confluent ECs showed that onset of either cyclic uniaxial or equibiaxial stretch caused a non-directional increase in edge ruffling. Edge activity was concentrated in a direction perpendicular to the stretch axis after 60 min, consistent with the direction of SF alignment. Rho-kinase inhibition caused reorientation of both stretch-induced edge ruffling and SF alignment parallel to the stretch axis. Arp2/3 inhibition attenuated stretch-induced cell elongation and disrupted polarized edge dynamics and microtubule organizing center reorientation, but it had no effect on the extent of SF reorientation. Disrupting localization of p21-activated kinase (PAK) did not prevent stretch-induced SF reorientation, suggesting that this Rac effector is not critical in regulating stretch-induced cytoskeletal remodeling. Overall, these results suggest that directional edge ruffling is not a primary mechanism that guides SF reorientation in response to stretch; the two events are coincident but not causal. PMID:25821527

  11. Bmp indicator mice reveal dynamic regulation of transcriptional response.

    Directory of Open Access Journals (Sweden)

    Anna L Javier

    Full Text Available Cellular responses to Bmp ligands are regulated at multiple levels, both extracellularly and intracellularly. Therefore, the presence of these growth factors is not an accurate indicator of Bmp signaling activity. While a common approach to detect Bmp signaling activity is to determine the presence of phosphorylated forms of Smad1, 5 and 8 by immunostaining, this approach is time consuming and not quantitative. In order to provide a simpler readout system to examine the presence of Bmp signaling in developing animals, we developed BRE-gal mouse embryonic stem cells and a transgenic mouse line that specifically respond to Bmp ligand stimulation. Our reporter identifies specific transcriptional responses that are mediated by Smad1 and Smad4 with the Schnurri transcription factor complex binding to a conserved Bmp-Responsive Element (BRE, originally identified among Drosophila, Xenopus and human Bmp targets. Our BRE-gal mES cells specifically respond to Bmp ligands at concentrations as low as 5 ng/ml; and BRE-gal reporter mice, derived from the BRE-gal mES cells, show dynamic activity in many cellular sites, including extraembryonic structures and mammary glands, thereby making this a useful scientific tool.

  12. Experimental measurement of utricle system dynamic response to inertial stimulus.

    Science.gov (United States)

    Dunlap, M D; Grant, J W

    2014-08-01

    The membranous utricle sac of the red-eared turtle was mounted in a piezoelectric actuated platform mounted on the stage of a light microscope. The piezoelectric actuator oscillated the base of the neuroepithelium along a linear axis. Displacements were in the plane of the utricle and consisted of a linear sinusoidal-sweep signal starting at 0 and increasing to 500 Hz over 5 s. This inertial stimulus caused measurable shear displacement of the otoconial layer's dorsal surface, resulting in shear deformation of the gelatinous and column filament layers. Displacements of the otoconial layer and a reference point on the neuroepithelium were filmed at 2,000 frames/s with a high-speed video camera during oscillations. Image registration was performed on the video to track displacements with a resolution better than 15 nm. The displacement waveforms were then matched to a linear second-order model of the dynamic system. The model match identified two system mechanical parameters-the natural circular frequency ω n and the damping ratio ζ-that characterized the utricle dynamic response. The median values found for the medial-lateral axis on 20 utricles with 95 % confidence intervals in parenthesis were as follows: ω n = 374 (353, 396) Hz and ζ = 0.50 (0.47, 0.53). The anterior-posterior axis values were not significantly different: ω n = 409 (390, 430) Hz and ζ = 0.53 (0.48, 0.57). The results have two relevant and significant dynamic system findings: (1) a higher than expected natural frequency and (2) significant under damping. Previous to this study, utricular systems were treated as overdamped and with natural frequencies much lower that measured here. Both of these system performance findings result in excellent utricle time response to acceleration stimuli and a broad frequency bandwidth up to 100 Hz. This study is the first to establish the upper end of this mechanical system frequency response of the utricle in any animal.

  13. Roman Catholic beliefs produce characteristic neural responses to moral dilemmas

    Science.gov (United States)

    Flexas, Albert; de Miguel, Pedro; Cela-Conde, Camilo J.; Munar, Enric

    2014-01-01

    This study provides exploratory evidence about how behavioral and neural responses to standard moral dilemmas are influenced by religious belief. Eleven Catholics and 13 Atheists (all female) judged 48 moral dilemmas. Differential neural activity between the two groups was found in precuneus and in prefrontal, frontal and temporal regions. Furthermore, a double dissociation showed that Catholics recruited different areas for deontological (precuneus; temporoparietal junction) and utilitarian moral judgments [dorsolateral prefrontal cortex (DLPFC); temporal poles], whereas Atheists did not (superior parietal gyrus for both types of judgment). Finally, we tested how both groups responded to personal and impersonal moral dilemmas: Catholics showed enhanced activity in DLPFC and posterior cingulate cortex during utilitarian moral judgments to impersonal moral dilemmas and enhanced responses in anterior cingulate cortex and superior temporal sulcus during deontological moral judgments to personal moral dilemmas. Our results indicate that moral judgment can be influenced by an acquired set of norms and conventions transmitted through religious indoctrination and practice. Catholic individuals may hold enhanced awareness of the incommensurability between two unequivocal doctrines of the Catholic belief set, triggered explicitly in a moral dilemma: help and care in all circumstances—but thou shalt not kill. PMID:23160812

  14. Roman Catholic beliefs produce characteristic neural responses to moral dilemmas.

    Science.gov (United States)

    Christensen, Julia F; Flexas, Albert; de Miguel, Pedro; Cela-Conde, Camilo J; Munar, Enric

    2014-02-01

    This study provides exploratory evidence about how behavioral and neural responses to standard moral dilemmas are influenced by religious belief. Eleven Catholics and 13 Atheists (all female) judged 48 moral dilemmas. Differential neural activity between the two groups was found in precuneus and in prefrontal, frontal and temporal regions. Furthermore, a double dissociation showed that Catholics recruited different areas for deontological (precuneus; temporoparietal junction) and utilitarian moral judgments [dorsolateral prefrontal cortex (DLPFC); temporal poles], whereas Atheists did not (superior parietal gyrus for both types of judgment). Finally, we tested how both groups responded to personal and impersonal moral dilemmas: Catholics showed enhanced activity in DLPFC and posterior cingulate cortex during utilitarian moral judgments to impersonal moral dilemmas and enhanced responses in anterior cingulate cortex and superior temporal sulcus during deontological moral judgments to personal moral dilemmas. Our results indicate that moral judgment can be influenced by an acquired set of norms and conventions transmitted through religious indoctrination and practice. Catholic individuals may hold enhanced awareness of the incommensurability between two unequivocal doctrines of the Catholic belief set, triggered explicitly in a moral dilemma: help and care in all circumstances-but thou shalt not kill.

  15. Dynamic Characteristics of the Hippocampal Neuron under Conductance’s Changing

    Directory of Open Access Journals (Sweden)

    Yueping Peng

    2011-02-01

    Full Text Available The hippocampal CA1 pyramid neuron has plenty of discharge actions. In the thesis, the dynamic characteristics of the hippocampal neuron model are analyzed and discussed by the neurodynamic theory and methods. Under a certain amplitude current’s stimulation, the change of gNa(the maximum conductance of the transient sodium channel and gKdr (the maximum conductance of the delay rectification potassium channel can cause different dynamic characteristics of the neuron model. The transient Na+ current(INa caused by gNa is indispensable in the discharge’s formation process of the model. The model can generate the discharge process only when gNa reaches a certain threshold. In the discharge process of the neuron model, gNa’s changing affects little and the ISIs approximate to a straight line. The delay rectification K+ current(Ikdr caused by gKdr isn’t indispensable in the discharge’s formation process of the model. But gKdr’s changing affects much in the discharge process of the neuron model. With gKdr’s changing, the neuron model undergoes different dynamic bifurcation process, and has plenty of discharge patterns such as the chaos, period, and so on. This investigation is helpful to know and investigate the dynamic characteristics and the bifurcation mechanism of the hippocampal neuron; and it provides a certain theory assist to investigate the neural diseases such as the Alzheimer disease by neurodynamics.

  16. Parametric characteristic of the random vibration response of nonlinear systems

    Institute of Scientific and Technical Information of China (English)

    Xing-Jian Dong; Zhi-Ke Peng; Wen-Ming Zhang; Guang Meng; Fu-Lei Chu

    2013-01-01

    Volterra series is a powerful mathematical tool for nonlinear system analysis,and there is a wide range of non-linear engineering systems and structures that can be represented by a Volterra series model.In the present study,the random vibration of nonlinear systems is investigated using Volterra series.Analytical expressions were derived for the calculation of the output power spectral density (PSD) and input-output cross-PSD for nonlinear systems subjected to Gaussian excitation.Based on these expressions,it was revealed that both the output PSD and the input-output crossPSD can be expressed as polynomial functions of the nonlinear characteristic parameters or the input intensity.Numerical studies were carried out to verify the theoretical analysis result and to demonstrate the effectiveness of the derived relationship.The results reached in this study are of significance to the analysis and design of the nonlinear engineering systems and structures which can be represented by a Volterra series model.

  17. Analysis on nonlinear wind-induced dynamic response of membrane roofs with aerodynamic effects

    Institute of Scientific and Technical Information of China (English)

    LI Qing-xiang; SUN Bing-nan

    2008-01-01

    Based on the characteristics of membrane structures and the air influence factors, this paper presen-ted a method to simulate the air aerodynamic force effects including the added air mass, the acoustic radiation damping and the pneumatic stiffness. The infinite air was modeled using the acoustic fluid element of commer-cial FE software and the finite element membrane roof models were coupled with fluid models. A comparison be-tween the results obtained by IrE computation and those obtained by the vibration experiment for a cable-mem-brane verified the validity of the method. Furthermore, applying the method to a flat membrane roof structure and using its wind tunnel test results, the analysis of nonlinear wind-induced dynamic responses for such geo-metrically nonlinear roofs, including the roof-air coupled model was performed. The result shows that the air has large influence on vibrating membrane roofs according to results of comparing the nodal time-history displace-ments, accelerations and stress of the two different cases. Meantime, numerical studies show that the method developed can successfully solve the nonlinear wind-induced dynamic response of the membrane roof with aero-dynamic effects.

  18. Nonlinear dynamic response of an electrically actuated imperfect microbeam resonator

    KAUST Repository

    Ruzziconi, Laura

    2013-08-04

    We present a study of the dynamic behavior of a MEMS device constituted of an imperfect clamped-clamped microbeam subjected to electrostatic and electrodynamic actuation. Our objective is to develop a theoretical analysis, which is able to describe and predict all the main relevant aspects of the experimental response. Extensive experimental investigation is conducted, where the main imperfections coming from microfabrication are detected and the nonlinear dynamics are explored at increasing values of electrodynamic excitation, in a neighborhood of the first symmetric resonance. The nonlinear behavior is highlighted, which includes ranges of multistability, where the non-resonant and the resonant branch coexist, and intervals where superharmonic resonances are clearly visible. Numerical simulations are performed. Initially, two single mode reduced-order models are considered. One is generated via the Galerkin technique, and the other one via the combined use of the Ritz method and the Padé approximation. Both of them are able to provide a satisfactory agreement with the experimental data. This occurs not only at low values of electrodynamic excitation, but also at higher ones. Their computational efficiency is discussed in detail, since this is an essential aspect for systematic local and global simulations. Finally, the theoretical analysis is further improved and a two-degree-of-freedom reduced-order model is developed, which is capable also to capture the measured second symmetric superharmonic resonance. Despite the apparent simplicity, it is shown that all the proposed reduced-order models are able to describe the experimental complex nonlinear dynamics of the device accurately and properly, which validates the proposed theoretical approach. Copyright © 2013 by ASME.

  19. Shock responses of nanoporous aluminum by molecular dynamics simulations

    CERN Document Server

    Xiang, Meizhen; Yang, Yantao; Liao, Yi; Wang, Kun; Chen, Yun; Chen, Jun

    2016-01-01

    We present systematic investigations on the shock responses of nanoporous aluminum (np-Al) by nonequilibrium molecular dynamics simulations. The dislocation nucleation sites are found to concentrate in low latitude region near the equator of the spherical void surfaces. We propose a continuum wave reflection theory and a resolved shear stress model to explain the distribution of dislocation nucleation sites. The simulations reveals two mechanisms of void collapse: the plasticity mechanism and the internal jetting mechanism. The plasticity mechanism, which leads to transverse collapse of voids, prevails under relatively weaker shocks; while the internal jetting mechanism, which leads to longitudinal filling of the void vacuum, plays more significant role as the shock intensity increases. In addition, an abnormal thermodynamic phenomenon (i.e., arising of temperature with pressure dropping) in shocked np-Al is discovered. This phenomenon is incompatible with the conventional Rankine-Hugoniot theory, and is expl...

  20. Dynamic Bridge Response for a Bridge-friendly Truck

    Directory of Open Access Journals (Sweden)

    V. Šmilauer

    2004-01-01

    Full Text Available A truck with controlled semi-active suspensions traversing a bridge is examined for benefits to the bridge structure. The original concept of a road-friendly truck was extended to a bridge-friendly vehicle, using the same optimization tools. A half-car model with two independently driven axles is coupled with simply supported bridges (beam, slab model with the span range from 5 m to 50 m. Surface profile of the bridge deck is either stochastic or in the shape of a bump or a pot in the mid-span. Numerical integration in the MATLAB/SIMULINK environment solves coupled dynamic equations of motion with optimized truck suspensions. The rear axle generates the prevailing load and to a great extent determines the bridge response. A significant decrease in contact road-tire forces is observed and the mid-span bridge deflections are on average smaller, when compared to commercial passive suspensions. 

  1. Dynamic response of shear thickening fluid under laser induced shock

    Science.gov (United States)

    Wu, Xianqian; Zhong, Fachun; Yin, Qiuyun; Huang, Chenguang

    2015-02-01

    The dynamic response of the 57 vol./vol. % dense spherical silica particle-polyethylene glycol suspension at high pressure was investigated through short pulsed laser induced shock experiments. The measured back free surface velocities by a photonic Doppler velocimetry showed that the shock and the particle velocities decreased while the shock wave transmitted in the shear thickening fluid (STF), from which an equation of state for the STF was obtained. In addition, the peak stress decreased and the absorbed energy increased rapidly with increasing the thickness for a thin layer of the STF, which should be attributed to the impact-jammed behavior through compression of particle matrix, the deformation or crack of the hard-sphere particles, and the volume compression of the particles and the polyethylene glycol.

  2. Dynamic adjustment of parental care in response to perceived paternity.

    Science.gov (United States)

    Neff, B D; Gross, M R

    2001-08-07

    Theories of parental care evolution predict that genetic relatedness will be an important variable in the amount of care a parent provides. However, current inferences of relatedness-based parental investment from studies in humans and birds remain challenged. No study has yet demonstrated parental care adjustment in a manner uncomplicated by life-history correlates or experimental design. We now present a unique test that controls for individual life histories and demonstrates paternity-related dynamic adjustments in parental care. Brood-rearing male bluegill sunfish (Lepomis macrochirus) that are cuckolded to a varying degree will either increase or decrease their parental investment in response to changing information on paternity during brood development. Specifically, as parental males detect paternity lost to cuckolders and, hence, a reduction in the value of their brood, they adaptively lower their level of parental care. Conversely, if they detect that their paternity is higher than previously assessed, they adaptively raise their level of parental care. This dynamic adjustment during brood rearing indicates the importance of genetic relatedness in parental investment decisions and provides needed empirical support for theoretical predictions.

  3. Forest vegetation dynamics and its response to climate changes

    Science.gov (United States)

    Zoran, Maria A.; Zoran, Liviu Florin V.; Dida, Adrian I.

    2016-10-01

    Forest areas are experiencing rapid land cover change caused by human-induced land degradation and extreme climatic events. Satellite remote sensing provides a useful tool to capture the temporal dynamics of forest vegetation change in response to climate shifts, at spatial resolutions fine enough to capture the spatial heterogeneity. Frequent satellite data products, for example, can provide the basis for studying time-series of biophysical parameters related to vegetation dynamics. Vegetation index time series provide a useful way to monitor forest vegetation phenological variations. In this study, we used MODIS Terra/Aqua time-series data, along with yearly and monthly net radiation, air temperature, and precipitation data to examine the feedback mechanisms between climate and forest vegetation. Have been quantitatively described Normalized Difference Vegetation Index(NDVI) /Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), Evapotranspiration (ET) and Gross Primary Production (GPP) temporal changes for Cernica- Branesti forest area, a periurban zone of Bucharest city in Romania, from the perspective of vegetation phenology and its relation with climate changes and extreme climate events (summer heat waves). A time series from 2000 to 2016 of the MODIS Terra was analyzed to extract forest biophysical parameters anomalies. Forest vegetation phenology analyses were developed for diverse forest land-covers providing a useful way to analyze and understand the phenology associated to those landcovers. Correlations between NDVI/EVI , LAI, ET and GPP time series and climatic variables have been computed.

  4. The dynamic response of carbon fiber-filled polymer composites

    Directory of Open Access Journals (Sweden)

    Patterson B.

    2012-08-01

    Full Text Available The dynamic (shock responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little-to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE composite to 18.6 GPa in the through-thickness direction, in which the shock propagates normal to the fibers. The data are best represented by a linear Rankine-Hugoniot fit: Us = 2.87 + 1.17 ×up(ρ0 = 1.536g/cm3. The shock wave structures were found to be highly heterogeneous, both due to the anisotropic nature of the fiber-epoxy microstructure, and the high degree of void volume. Plate impact experiments were also performed on a carbon fiber-filled phenolic (CP composite to much higher shock input pressures, exceeding the reactants-to-products transition common to polymers. The CP was found to be stiffer than the filament-wound CE in the unreacted Hugoniot regime, and transformed to products near the shock-driven reaction threshold on the principal Hugoniot previously shown for the phenolic binder itself. [19] On-going research is focused on interrogating the direction-dependent dyanamic response and dynamic failure strength (spall for the CE composite in the TT and 0∘ (fiber directions.

  5. The dynamic response of carbon fiber-filled polymer composites

    Science.gov (United States)

    Dattelbaum, D. M.; Gustavsen, R. L.; Sheffield, S. A.; Stahl, D. B.; Scharff, R. J.; Rigg, P. A.; Furmanski, J.; Orler, E. B.; Patterson, B.; Coe, J. D.

    2012-08-01

    The dynamic (shock) responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little-to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE) composite to 18.6 GPa in the through-thickness direction, in which the shock propagates normal to the fibers. The data are best represented by a linear Rankine-Hugoniot fit: Us = 2.87 + 1.17 ×up(ρ0 = 1.536g/cm3). The shock wave structures were found to be highly heterogeneous, both due to the anisotropic nature of the fiber-epoxy microstructure, and the high degree of void volume. Plate impact experiments were also performed on a carbon fiber-filled phenolic (CP) composite to much higher shock input pressures, exceeding the reactants-to-products transition common to polymers. The CP was found to be stiffer than the filament-wound CE in the unreacted Hugoniot regime, and transformed to products near the shock-driven reaction threshold on the principal Hugoniot previously shown for the phenolic binder itself. [19] On-going research is focused on interrogating the direction-dependent dyanamic response and dynamic failure strength (spall) for the CE composite in the TT and 0∘ (fiber) directions.

  6. 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.

    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 characteristic

  7. A method of moments for calculating dynamic responses beyond linear response theory

    Institute of Scientific and Technical Information of China (English)

    Kang Yan-Mei; Xu Jian-Xue; Xie Yong

    2005-01-01

    A method of moments for calculating the dynamic response of periodically driven overdamped nonlinear stochastic systems in the general response sense is proposed, which is a modification of the method of moments confined within linear response theory. The calculating experience suggests that the proposed technique is simple and efficient in implementation, and the comparison with stochastic simulation shows that the first three orders of susceptibilities calculated by the proposed technique have high accuracy. The dependence of the spectral amplification parameters at the first three harmonics on the noise intensity is also investigated, and another observed phenomenon of stochastic resonance in the systems induced by the location of a single periodic orbit is disclosed and explained.

  8. Dynamic characteristics and control of jet engines. Jet engine no dynamics to seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, N. (National Aerospace Lab., Chofu, Tokyo (Japan))

    1993-06-10

    The recent controller of a jet engine is called as Full Authority Digital Engine Controller (FADEC). This means that the whole operation from starting to shut down of an engine is carried out by the electric digital control. Many studies on the control of a jet engine by the electric digital control have been conducted since the past, this advantages were also clarified, but, since the reliability of electrical machines was low, this was not put into use at once. However, FADEC became possible since the technical reform concerning to the increasing reliability and environment-resisting property, small type with low weight and low cost of electrical machines was performed. In this paper, FADEC system was summarized, in connection with this system, studies on the dynamics and multi-variables control of a jet engine were described. 15 refs., 11 figs., 1 tab.

  9. Dynamic characteristics of multi-walled carbon nanotubes under a transverse magnetic field

    Indian Academy of Sciences (India)

    S Li; H J Xie; X Wang

    2011-02-01

    This paper reports the results of an investigation into the effect of transverse magnetic fields on dynamic characteristics of multi-walled carbon nanotubes (MWNTs). Couple dynamic equations of MWNTs subjected to a transverse magnetic field are derived and solved by considering the Lorentz magnetic forces induced by a transverse magnetic field exerted on MWCNTs. Results show that the transverse magnetic field exerted on MWNTs makes the lowest frequency of the MWNTs nonlinearly decrease and the highest frequency, changeless. When the strength of applied transverse magnetic fields is larger than a given value the two walls of MWNTs appear in the radial and axial coaxial vibration phenomena.

  10. Dynamic characteristics of helium adsorbents. Influence of the heat removal conditions

    Science.gov (United States)

    Shcherbachenko, R. I.; Grigor'ev, V. N.

    2008-06-01

    The static and dynamic characteristics of the adsorbent SKN-1K at 4.2K are investigated under conditions corresponding to the working conditions of adsorption pumps in dilution refrigerators. It is shown that gluing this adsorbent to the cooled surface leads to a substantial lowering of the pressure in the pump in the dynamic regime. On the basis of experimental data for the glued and free adsorbent an estimate is made of the hydrodynamic contribution to the pressure due to the resistance of the pores of the adsorbent. This estimate falls within the error of measurement.

  11. Dynamic Characteristics of Growing Modes of Raman Instability from Intense Laser Beam Propagating Through Plasma

    Institute of Scientific and Technical Information of China (English)

    LIU Shi-Bing; CHEN Tao; CHEN Shi-Gang

    2004-01-01

    An essential dispersion relation,which can describe the dynamic properties of stimulated Raman scattering instability as a laser beam propagates through plasmas,is derived analytically.The development of growth mode,angle distribution,and temperature dependence of the instabilities are presented by solving this dispersion relation numerically.A significant dynamic characteristic has been revealed that the temperature increasing of the electron would result in redshift of scattered spectrum at high laser intensities.Furthermore,a novel modulational instability with double-peak temporal structure appears in a limited density region because of the coupling of scattered upshift and downshift waves.

  12. Bronchodilator responsiveness as a phenotypic characteristic of established chronic obstructive pulmonary disease

    DEFF Research Database (Denmark)

    Albert, Paul; Agusti, Alvar; Edwards, Lisa

    2012-01-01

    Bronchodilator responsiveness is a potential phenotypic characteristic of chronic obstructive pulmonary disease (COPD). We studied whether change in lung function after a bronchodilator is abnormal in COPD, whether stable responder subgroups can be identified, and whether these subgroups experien...

  13. IR image quality assessment and real-time optimum seeking method based on dynamic visual characteristics

    Science.gov (United States)

    Li, Bin; Liu, Gang; Gao, Yongmin; Lei, Hao; Wu, Haiying; Wang, Yu; Rong, Xiaolong

    2016-10-01

    Image quality is an important factor that influences the dynamic target information perception; it is the key factor of real-time target state analysis and judgment. In order to solve the multi-observation station comparison and video optimum seeking problem in the process of target information perception and recognition, an image quality assessment method based on visual characteristics is proposed for infrared target tracking. First, it analyses the basic infrared target image characteristics and application requirements, analyses the status and problems of the multi station optimum seeking technology. According to the expected research results, the processing flow of image processing is established. Then, the image quality objective assessment index is established, which reflects the basic characteristics of the target image, and the assessment index is integrated into the normalized assessment function. According to the quality assessment function, the infrared image quality assessment based on infrared target recognition and image analysis processing is realized, which is mainly characterized by the region of interest and dynamic visual characteristics. And on the basis of this technology, the real-time optimum seeking of multi station infrared target tracking image is completed. In order to verify the effectiveness of the method and the practical application effect, it designs the quality assessment and comparison of different station infrared images. Example shows that the method proposed in this paper can realize multi-observation station infrared image assessment comparison, image quality sorting, the optimum seeking of the infrared image based on the quality assessment. The results accord with the characteristics of infrared target image and dynamic visual characteristics.

  14. Nonlinear dynamic characteristics of piles embedded in rock%嵌岩桩非线性动力学特性

    Institute of Scientific and Technical Information of China (English)

    胡春林; 程昌钧; 胡胜刚

    2007-01-01

    The nonlinear dynamic characteristics of a pile embedded in a rock were investigated.Suppose that both the materials of the pile and the soil around the pile obey nonlinear elastic and linear viscoelastic constitutive relations.The nonfinear partial differential equation governing the dynamm characteristics of the pile was first derived.The Galerkin method Wasusedto simplify the equation and to obtain a nonlinear ordinary differential equation.The methods in nonlinear dynamics were employed to solve the simplified dynamical system,and the time-path curves,phase-trajectory diagrams,power spectrum,the dynamic characteristics of the system were also considered in detail.

  15. Super-resolution infrared time measurement method based on target dynamic characteristics

    Science.gov (United States)

    Li, Bin; Hu, Qiuping; Tang, Zili; Zhang, Sanxi; Zhang, Hua; Yue, Peng; Liu, Biao

    2016-10-01

    High precision time control in the use of weapons and equipment is an important part of product design and development. In order to satisfy the data acquisition requirement of high accuracy and reliability in the rapid flight process, the super-resolution time measurement method based on target dynamic characteristics was put forward and proved by the cabin opening time measurement experiment. First, the changes of explosion pressure wave and image in the cabin opening process were analyzed in detail. The change regulation of explosion flame shape was analyzed by the characteristics of typical pressure wave, and then the high frequency images of the explosion process were shot by high speed camera. The change regulation of the infrared image was obtained through the comparison of visible and infrared image mechanism. Then, combined with the target motion features, and the observed station parameters, the observation model of movement process was built. On the basis of the above research, the infrared characteristic and the movement characteristic were transformed, and the super resolution model was established. For test method, combined with the actual class time measuring process in experimental design, to obtain the special radar for measuring high precision open class time as the true value of the precision appraisal. Experimental results show that the infrared feature and motion feature can realize open class time super resolution measurement, can effectively improve the accuracy and reliability of the data, to achieve specific action of high accuracy measurement that plays an important role by making use of the target dynamic characteristics.

  16. Molecular Dynamics of the Shewanella oneidensis Response to Chromate Stress

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Steven D [ORNL; Thompson, Melissa R [ORNL; Verberkmoes, Nathan C [ORNL; Chourey, Karuna [ORNL; Shah, Manesh B [ORNL; Zhou, Jizhong [ORNL; Hettich, Robert {Bob} L [ORNL; Thompson, Dorothea K [ORNL

    2006-01-01

    Temporal genomic profiling and whole-cell proteomic analyses were performed to characterize the dynamic molecular response of the metal-reducing bacterium Shewanella oneidensis MR-1 to an acute chromate shock. The complex dynamics of cellular processes demand the integration of methodologies that describe biological systems at the levels of regulation, gene and protein expression, and metabolite production. Genomic microarray analysis of the transcriptome dynamics of midexponential phase cells subjected to 1 mM potassium chromate (K2CrO4) at exposure time intervals of 5, 30, 60, and 90 min revealed 910 genes that were differentially expressed at one or more time points. Strongly induced genes included those encoding components of a TonB1 iron transport system (tonB1-exbB1-exbD1), hemin ATP-binding cassette transporters (hmuTUV), TonB-dependent receptors as well as sulfate transporters (cysP, cysW-2, and cysA-2), and enzymes involved in assimilative sulfur metabolism (cysC, cysN, cysD, cysH, cysI, and cysJ). Transcript levels for genes with annotated functions in DNA repair (lexA, recX, recA, recN, dinP, and umuD), cellular detoxification (so1756, so3585, and so3586), and two-component signal transduction systems (so2426) were also significantly upregulated (p < 0.05) in Cr(VI)-exposed cells relative to untreated cells. By contrast, genes with functions linked to energy metabolism, particularly electron transport (e.g. so0902-03-04, mtrA, omcA, and omcB), showed dramatic temporal alterations in expression with the majority exhibiting repression. Differential proteomics based on multidimensional HPLC-MS/MS was used to complement the transcriptome data, resulting in comparable induction and repression patterns for a subset of corresponding proteins. In total, expression of 2,370 proteins were confidently verified with 624 (26%) of these annotated as hypothetical or conserved hypothetical proteins. The initial response of S. oneidensis to chromate shock appears to

  17. Simulation on Dynamic Characteristic of Negative Resistance Arc in Pulsed TIG Welding

    Institute of Scientific and Technical Information of China (English)

    YANG Lijun; HAN Pengbo; DONG Tianshun; ZHANG Jian; XU Licheng

    2007-01-01

    A mathematical model is established on the basis of the physical characteristic of the negative resistance arc when a low current of 0-50 A is applied in pulsed TIG welding. The simulation model converted from the mathematical model is run in MATLAB environment, and the discussion is focused on the way the peak current ranging from 29 A to 50 A and the time constant of arc in the span of 0.003-0.006 s influence the simulating results and the dynamic characteristic. The simulating data are close to that of welding experiments and correspond to the theoretical conclusion.

  18. Effect Of Dynamic Characteristics of Power Supplies on Aerosol Composition While Welding With Coated Electrodes

    Science.gov (United States)

    Il'yaschenko, D. P.; Chinakhov, D. A.; Sadikov, I. D.

    2016-08-01

    In the context of a significant increase in production output and use of welding technologies in the manufacturing of engineering products the problem of hygienic characteristics of working conditions in arc fusion welding is becoming increasingly important. The work represents how the dynamic characteristics of a power supply affect the transfer of alloying elements from a coated electrode into a base metal, a slag phase and a solid component of welding fumes. Short-circuit current limiting in inverters reduces overheating of electrode metal drops by 15%; welding fumes quantitative component - to 38%; manganese - to 30%; thermal radiation intensity - by 37%.

  19. Dynamic Control of Electric Output Characteristics of Proton Exchange Membrane Fuel Cell System

    Institute of Scientific and Technical Information of China (English)

    刘星则; 朱新坚

    2005-01-01

    This paper discusses dynamic characteristics of proton exchange membrane fuel cell (PEMFC) under rapid fluctuation of power demand. Wavelet neural network is adopted in the identification of the characteristic curve to predict the voltage. The system control scheme of the voltage and power is introduced. The corresponding schemes for voltage and power control are studied. MATLAB is used to simulate the control system. The results reveal that the adopted control schemes can produce expected effects. Corresponding anti-disturbance and robustness simulation are also carried out. The simulation results show that the implemented control schemes have better robustness and adaptability.

  20. 动态磁化特性模拟%Dynamic Magnetizing Characteristic Simulation

    Institute of Scientific and Technical Information of China (English)

    陈季权; 王如玫

    2001-01-01

    A method of the simulation of the dynamic magnetizing characteristic about the transformer core material is introduced.By this method,measuring hysteresis loop only once,the magnetic characteristic of ferromagnetic materials in each working state can be simulated accurately.%介绍了变压器铁心材料动态磁特性的模拟拟合方法,用此方法,只要做一次磁滞回线测定,就能比较准确地模拟出铁磁材料在各种不同工作点的磁化特性。

  1. Inferring Characteristics of Sensorimotor Behavior by Quantifying Dynamics of Animal Locomotion

    Science.gov (United States)

    Leung, KaWai

    Locomotion is one of the most well-studied topics in animal behavioral studies. Many fundamental and clinical research make use of the locomotion of an animal model to explore various aspects in sensorimotor behavior. In the past, most of these studies focused on population average of a specific trait due to limitation of data collection and processing power. With recent advance in computer vision and statistical modeling techniques, it is now possible to track and analyze large amounts of behavioral data. In this thesis, I present two projects that aim to infer the characteristics of sensorimotor behavior by quantifying the dynamics of locomotion of nematode Caenorhabditis elegans and fruit fly Drosophila melanogaster, shedding light on statistical dependence between sensing and behavior. In the first project, I investigate the possibility of inferring noxious sensory information from the behavior of Caenorhabditis elegans. I develop a statistical model to infer the heat stimulus level perceived by individual animals from their stereotyped escape responses after stimulation by an IR laser. The model allows quantification of analgesic-like effects of chemical agents or genetic mutations in the worm. At the same time, the method is able to differentiate perturbations of locomotion behavior that are beyond affecting the sensory system. With this model I propose experimental designs that allows statistically significant identification of analgesic-like effects. In the second project, I investigate the relationship of energy budget and stability of locomotion in determining the walking speed distribution of Drosophila melanogaster during aging. The locomotion stability at different age groups is estimated from video recordings using Floquet theory. I calculate the power consumption of different locomotion speed using a biomechanics model. In conclusion, the power consumption, not stability, predicts the locomotion speed distribution at different ages.

  2. Effects of torque spring, CCL and latch mechanism on dynamic response of planar solar arrays with multiple clearance joints

    Science.gov (United States)

    Li, Yuanyuan; Wang, Zilu; Wang, Cong; Huang, Wenhu

    2017-03-01

    This paper numerically investigates the effects of torque spring, close cable loop (CCL) configuration and latch mechanism on the overall dynamic characteristics of a deployable solar arrays system considering joint clearance; and presents significant guidance for the key parameters design of these three mechanisms. A typical mechanism composed of a main-body with a yoke and two panels is used as a demonstration case to study the dynamic response of the deployable solar array system in the deployment process and post-latch phase. The normal contact force model and tangential friction model in clearance joint are established using nonlinear contact force model and modified Coulomb friction model, respectively. The numerical simulation results reveal that the joint clearances influence the dynamic characteristics of the deployable space solar arrays in different operation phases. Besides, parametric studies indicate some rules to design preload and stiffness coefficient of torque spring, equivalent stiffness coefficient of CCL mechanism and stiffness and damping coefficient of latch mechanism.

  3. Dynamics of immune response and drug resistance in malaria infection

    Directory of Open Access Journals (Sweden)

    Gurarie David

    2006-10-01

    Full Text Available Abstract Background Malaria parasites that concurrently infect a host compete on the basis of their intrinsic growth rates and by stimulating cross-reactive immune responses that inhibit each others' growth. If the phenotypes also show different drug sensitivities ('sensitive' vs. 'resistant' strains, drug treatment can change their joint dynamics and the long-term outcome of the infection: most obviously, persistent drug pressure can permit the more resistant, but otherwise competitively-inferior, strains to dominate. Methods Here a mathematical model is developed to analyse how these and more subtle effects of antimalarial drug use are modulated by immune response, repeated re-inoculation of parasites, drug pharmacokinetic parameters, dose and treatment frequency. Results The model quantifies possible effects of single and multiple (periodic treatment on the outcome of parasite competition. In the absence of further inoculation, the dosage and/or treatment frequency required for complete clearance can be estimated. With persistent superinfection, time-average parasite densities can be derived in terms of the basic immune-regulating parameters, the drug efficacy and treatment regimen. Conclusion The functional relations in the model are applicable to a wide range of conditions and transmission environments, allowing predictions to be made on both the individual and the community levels, and, in particular, transitions from drug-sensitive to drug-resistant parasite dominance to be projected on both levels.

  4. Ultrafast dynamic response of single crystal β-HMX

    Science.gov (United States)

    Zaug, Joseph M.; Armstrong, Michael R.; Crowhurst, Jonathan C.; Radousky, Harry B.; Ferranti, Louis; Swan, Raymond; Gross, Rick; Teslich, Nick E.; Wall, Mark A.; Austin, Ryan A.; Fried, Laurence E.

    2017-01-01

    We report results from ultrafast compression experiments conducted on β-HMX single crystals. Results consist of nominally 12 picosecond time-resolved wave profile data, (ultrafast time domain interferometry -TDI measurements), that were analyzed to determine high-velocity wave speeds as a function of piston velocity. TDI results are used to validate calculations of anisotropic stress-strain behavior of shocked loaded energetic materials. Our previous results derived using a 350 ps duration compression drive revealed anisotropic elastic wave response in single crystal β-HMX from (110) and (010) impact planes. Here we present results using a 1.05 ns duration compression drive with a 950 ps interferometry window to extend knowledge of the anisotropic dynamic response of β-HMX within eight microns of the initial impact plane. We observe two distinct wave profiles from (010) and three wave profiles from (010) impact planes. The (110) impact plane wave speeds typically exceed (010) impact plane wave speeds at the same piston velocities. The development of multiple hydrodynamic wave profiles begins at 20 GPa for the (110) impact plane and 28 GPa for the (10) impact plane. We compare our ultrafast TDI results with previous gun and plate impact results on β-HMX and PBX9501.

  5. Facile Fabrication of Composite Membranes with Dual Thermo- and pH-Responsive Characteristics.

    Science.gov (United States)

    Ma, Bing; Ju, Xiao-Jie; Luo, Feng; Liu, Yu-Qiong; Wang, Yuan; Liu, Zhuang; Wang, Wei; Xie, Rui; Chu, Liang-Yin

    2017-04-11

    Facile fabrication of novel functional membranes with excellent dual thermo- and pH-responsive characteristics has been achieved by simply designing dual-layer composite membranes. pH-Responsive poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers and polystyrene blended with thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) nanogels are respectively used to construct the top layer and bottom layer of composite membranes. The stretching/coiling conformation changes of the P4VP chains around the pKa (~3.5-4.5) provide the composite membranes with extraordinary pH-responsive characteristics, and the volume phase transitions of PNIPAM nanogels at the pore/matrix interfaces in the bottom layer around the volume phase transition temperature (VPTT, ~33 oC) provide the composite membranes with great thermo-responsive characteristics. The microstructures, permeability performances and dual stimuli-responsive characteristics can be well tuned by adjusting the content of PNIPAM nanogels and the thickness of the PS-b-P4VP top layer. The water fluxes of the composite membranes can be changed in order of magnitude by changing the environment temperature and pH, and the dual thermo- and pH-responsive permeation performances of the composite membranes are satisfactorily reversible and reproducible. The membrane fabrication strategy in this work provides valuable guidance for further development of dual stimuli-responsive membranes or even multi stimuli-responsive membranes.

  6. An experimental and numerical study on dynamic characteristic of linear compressor in refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun; Roh, Chul-gi; Kim, Jong-kwon; Shin, Jong-min [Digital Appliance Company Laboratory, LG Electronics 391-2, Ga Eum Jeong-Dong, Changwon Gyeong Nam 641-711 (Korea); Hwang, Yujin; Lee, Jae-keun [School of Mechanical Engineering, Pusan National University, San 30, Changjeon-Dong, Keumjeong-Ku, Pusan 609-735 (Korea)

    2009-11-15

    This paper presents experimental and numerical results of the dynamic characteristic and COP of a linear compressor in a refrigeration system using R600 refrigerant. The numerical analysis consists of a model and a simulation that includes the linear compressor. In this study, the dynamic characteristic of the natural frequency of the linear compressor is validated by comparing the simulation results with the experimental results. To investigate the effect of system resonance on the performance of linear compressor, COP is evaluated under evaporator pressure in the range of 48.3-63.2 kPa abs, and condenser pressure in the range of 439.0-573.3 kPa abs. Based on the results, the system resonance at the TDC was varied within a range of 3% under the test conditions. COP and its sensitivity were found to vary within 3% according to the operating frequency of the system ranging from 48.5 to 51.5 Hz. (author)

  7. Dynamical characteristics of pre-epileptic seizures in rats with recurrence quantification analysis

    Science.gov (United States)

    Li, Xiaoli; Ouyang, Gaoxiang; Yao, Xin; Guan, Xinping

    2004-11-01

    Understanding the transition of brain activity towards an epileptic seizure, called pre-epileptic seizure, is a challenge in epilepsy. In this Letter, a recurrence quantification analysis (RQA) is proposed to describe dynamical characteristics of EEG (electroencephalograph) recordings on rat experiments, which is helpful to predict seizures. One of the advantages of this method does not require any assumptions to EEG data, such as linear, stationary, noiseless and so on. A series of experimental tests in this study show that the dynamical characteristics of EEG data with RQA can identify the differences among inter-ictal, pre-ictal and ictal phases; and support the hypothesis that complexity of brain electrical activity has a significant decrease prior to an epileptic seizure. This change could be useful in predicting epileptic seizures.

  8. Evaluation of the Growth Dynamics and Morphological Characteristics of Genetic Sources of Silybum marianum (L. Gaertn

    Directory of Open Access Journals (Sweden)

    Pavla Koláčková

    2015-01-01

    Full Text Available The aim of this work was to evaluate the growth dynamics and selected morphological characteristics of genetic sources of milk thistle (Silybum marianum L. Gaertn. for the further development of the minimal set of descriptors. Milk thistle is grown in the Czech Republic for its achenes; however, the quality of achenes can be reduced by many factors, by the occurrence of fungal pathogens mainly. The growth dynamics and morphological characteristics of milk thistle during the vegetation period in the years 2010–2013 at two localities were evaluated. The cluster analysis of the data showed the similarity for some of the accessions and confirmed the dependence of the data value to the climatic conditions. Source from Serbia, Slovakia, Romanian variety ’De Prahova’, German accessions SIL 2 and SIL 8, Hungarian accesion RCAT 040360 DDR and Czech variety ’Silyb’ seem to be promising genetic sources from the viewpoint of growth and development in the Czech Republic.

  9. TEST METHOD OF HIGH-SPEED ON-OFF VALVE DYNAMIC CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    According to the valve port features of high speed on-offvalve and its actions, the valve port can be simplified into an a-type half bridge construction. A method that tests the dynamic characteristics of the high speed on-off valve by the output pressure signal of the a-type half bridge is proposed. Having analyzed the factors related to the dynamic characteristics of an a-type half bridge, a rule for designing the outlet chamber's volume is worked out. According to the rule, a test stand is built to test the self-developed high-speed on-off valve. From the test results, it can be seen that with the outlet chamber's volume controlled by the rule the rise time of the pressure signals driven by signals with different frequencies changes very little. The test results conform to the simulation results, which proves the correctness of the method.

  10. 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.

  11. Effects of automobile steering characteristics on driver vehicle system dynamics in regulation tasks

    Science.gov (United States)

    Mcruer, D. T.; Klein, R.

    1975-01-01

    A regulation task which subjected the automobile to a random gust disturbance which is countered by driver control action is used to study the effects of various automobile steering characteristics on the driver/vehicle system. The experiments used a variable stability automobile specially configured to permit insertion of the simulated gust disturbance and the measurement of the driver/vehicle system characteristics. Driver/vehicle system dynamics were measured and interpreted as an effective open loop system describing function. Objective measures of system bandwidth, stability, and time delays were deduced and compared. These objective measures were supplemented by driver ratings. A tentative optimum range of vehicle dynamics for the directional regulation task was established.

  12. 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.

  13. Dynamic characteristics of the blisk with synchronized switch damping based on negative capacitor

    Science.gov (United States)

    Liu, J.; Li, L.; Huang, X.; Jezequel, L.

    2017-10-01

    In this paper, we propose a method to suppress the vibration of the integral bladed disk ('blisk' for short) in aero-engines using synchronized switch damping based on negative capacitor (SSDNC). Different from the classical piezoelectric shunt damping, SSDNC is a type of nonlinear piezoelectric damping. A multi-harmonic balance method combined with the alternating frequency/time method (MHBM-AFT) is used to predict and further analyze the dynamic characteristics of the electromechanical system, and an arc-length continuation technique is used to improve the convergence of the method. In order to validate the algorithm as well as to recognize the characteristics of the system with SSDNC, a two degree-of-freedom (2-DOF) system with SSDNC is studied at first. The nonlinear complex modal information is calculated and compared with those of the corresponding system with a linear RL shunt circuit. The results indicate that the natural frequencies and modal damping ratio do not change with the modal amplitude, which means that SSDNC has the same modal damping corresponding to different system energy levels. In addition, SSDNC can improve the damping level of all the modes nearly without affecting the natural frequencies of the system. Then, the forced response of the blisk with SSDNC in the frequency domain is calculated and analyzed, including a tuned blisk, which is excited by the traveling wave excitation with a single harmonic and multi-harmonic, and a mistuned blisk, which is excited by traveling wave excitation with a single harmonic and multi-harmonic. We present two advantages of the SSDNC technique when compared with piezoelectric shunt damping. First, SSDNC can suppress the vibration of the blisk under a multi-harmonic wideband the traveling wave, and second, the vibration suppression performance of SSDNC is insensitive to the mistuning of mechanical parameters of the blisk. The results will be of great significance in overcoming the problem of the amplitude

  14. Simulation of the dynamic response of radioactive material shipping package-railcar systems during coupling operations

    Energy Technology Data Exchange (ETDEWEB)

    Fields, S.R.

    1983-10-01

    The basic equations of the computer model CARDS (Cask-Railcar Dynamic Simulator), developed for the US Nuclear Regulatory Commission to simulate the dynamic behavior of radioactive material shipping package - railcar systems, are presented. A companion model, CARRS (Cask Railcar Response Spectrum Generator), that generates system response as frequency response spectra is also presented in terms of its basic equations. 1 reference, 18 figures.

  15. Simulation of the dynamic response of radioactive material shipping package - railcar systems during coupling operations

    Energy Technology Data Exchange (ETDEWEB)

    Fields, S.R.

    1981-12-01

    The basic equations of the computer model CARDS (Cask-Railcar Dynamic Simulator), developed for the U.S. Nuclear Regulatory Commission to simulate the dynamic behavior of radioactive material shipping package - railcar systems, are presented. A companion model, CARRS (Casks Railcar Response Spectrum Generator), that generates system response as frequency response spectra is also presented in terms of its basic equations.

  16. Synthesis of mechanisms with flexible centrifugal-inertial connections according to fixed dynamic characteristics

    Science.gov (United States)

    Ragulskis, K. M.; Yaroslavskiy, I. K.

    1973-01-01

    The criteria for the selection of dynamic characteristics of flexible centrifugal-inertial couplings are discussed. The basic properties considered are: (1) vibration isolation, (2) vibration quenching, and (3) transmission properties. It is stated that the most promising couplings are those with a nonlinear relation between the magnitude of the torque transmitted and the magnitude of deformation of the coupling. The efforts of various investigators are briefly analyzed. Mathematical models are developed to show the relationships of the parameters involved.

  17. Characteristic specific prioritized dynamic average burst round robin scheduling for uniprocessor and multiprocessor environment

    OpenAIRE

    Dash, Amar Ranjan; Sahu, Sandipta kumar; Samantra, Sanjay Kumar; Sabat, Sradhanjali

    2015-01-01

    CPU scheduling is one of the most crucial operations performed by operating systems. Different conventional algorithms like FCFS, SJF, Priority, and RR (Round Robin) are available for CPU Scheduling. The effectiveness of Priority and Round Robin scheduling algorithm completely depends on selection of priority features of processes and on the choice of time quantum. In this paper a new CPU scheduling algorithm has been proposed, named as CSPDABRR (Characteristic specific Prioritized Dynamic Av...

  18. Low-Dimensional Dynamical Characteristics of Shock Wave /Turbulent Boundary Layer Interaction in Conical Flows

    Science.gov (United States)

    2014-12-16

    Shock Wave /Turbulent Boundary Layer Interaction in Conical Flows FA9550-11-1-0203 Dr. Charles E. Tinney, Aerospace Engineering and Engineering...Low-Dimensional Dynamical Characteristics of Shock Wave /Turbulent Boundary Layer Interaction in Conical Flows Contract/Grant Number: FA9550-11-1-0203...driven by transonic resonance (Zaman et al, 2002). What is common about many of these planar nozzle studies is that there is just one single

  19. Loading Dynamics and Characteristics of a Far Off-Resonance Optical Dipole Trap

    Science.gov (United States)

    Mickelson, P. G.; Martinez, Y. N.; Nagel, S. B.; Traverso, A. J.; Killian, T. C.

    2007-10-01

    We implement an optical dipole trap in a crossed beam configuration for experiments with ultracold strontium. Strontium atoms cooled to nearly 1 μK are loaded into the optical dipole trap from a magneto-optical trap operating on the 689 nm intercombination line. Loading dynamics and characteristics of the far off-resonance dipole trap are explored as part of our group's study of ultracold collisions in strontium.

  20. How Dynamic Consumer Response, Competitor Response, Company Support, and Company Inertia Shape Long-Term Marketing Effectiveness

    OpenAIRE

    Koen Pauwels

    2004-01-01

    Long-term marketing effectiveness is a high-priority research topic for managers, and emerges from the complex interplay among dynamic reactions of several market players. This paper introduces restricted policy simulations to distinguish four dynamic forces: consumer response, competitor response, company inertia, and company support. A rich marketing dataset allows the analysis of price, display, feature, advertising, and product-line extensions. The first finding is that consumer response ...

  1. A new approach to improve dynamic characteristics of digitally controlled buck-boost dc-dc converter

    OpenAIRE

    2010-01-01

    This paper presents a new digital control buck-boost dc-dc converter with bias model to improve dynamic characteristics. The buck-boost converter needs to respond appropriately to changing input voltage and load change with wide input voltage. This approach makes adjustment to the bias value by input voltage and output current. As a result, it is revealed that not only the dynamic characteristics but also static characteristics can be improved and it is effective for wide range input voltage.

  2. Dynamics of a Delayed HIV-1 Infection Model with Saturation Incidence Rate and CTL Immune Response

    Science.gov (United States)

    Guo, Ting; Liu, Haihong; Xu, Chenglin; Yan, Fang

    2016-12-01

    In this paper, we investigate the dynamics of a five-dimensional virus model incorporating saturation incidence rate, CTL immune response and three time delays which represent the latent period, virus production period and immune response delay, respectively. We begin this model by proving the positivity and boundedness of the solutions. Our model admits three possible equilibrium solutions, namely the infection-free equilibrium E0, the infectious equilibrium without immune response E1 and the infectious equilibrium with immune response E2. Moreover, by analyzing corresponding characteristic equations, the local stability of each of the feasible equilibria and the existence of Hopf bifurcation at the equilibrium point E2 are established, respectively. Further, by using fluctuation lemma and suitable Lyapunov functionals, it is shown that E0 is globally asymptotically stable when the basic reproductive numbers for viral infection R0 is less than unity. When the basic reproductive numbers for immune response R1 is less than unity and R0 is greater than unity, the equilibrium point E1 is globally asymptotically stable. Finally, some numerical simulations are carried out for illustrating the theoretical results.

  3. 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.

  4. Research on electromagnetic relay's dynamic characteristics disturbed by uniform static magnetic field

    Institute of Scientific and Technical Information of China (English)

    Guo-fu ZHAI; Qi-ya WANG; Wan-bin REN

    2008-01-01

    Electromagnetic relay is a widely used apparatus which usually works in a magnetic disturbance environment. To evaluate its electromagnetic compatibility (EMC) in a static magnetic field, dynamic characteristics of a clapper relay in a uniform static magnetic field situation based on the finite element method (FEM) is studied. Influences of the magnetic field on dynamic parameters (delay time, pick-up time, end pressure, and final velocity) as well as a situation in which the relay cannot function normally are analyzed. Simulation reveals that the external magnetic field which weakens the relay's air-gap field has a greater influence on the relay's dynamic parameters than the one strengthening the field. The validity of the simulation is verified by measured results of coil current and armature displacement.

  5. Study on Simulation Method of Pipeline Networks' Dynamic Characteristic in Hydraulic Manifold Block

    Institute of Scientific and Technical Information of China (English)

    CAO Yu-ning; TIAN Shu-jun; WANG Yong-an; GAO Yan-ming

    2008-01-01

    In the design of Hydraulic Manifold Blocks (HMB), dynamic performance of inner pipeline networks usually should be evaluated.To meet the design requirements, dynamic characteristic simulation is often needed.Based on comprehensive study on the existing simulation methods, a new method combined of Power Bond Graph(PBG) and Computational Fluid Dynamic (CFD) is proposed.In this method, flow field of typical channels inside HMB is analyzed with CFD to obtain the local resistance coefficients.Then, with these coefficients, a new sectional lumped-parameter model including kinetic friction factor is developed using PBG.A typical HMB design example is given and the comparison between the simulation and the experimental results demonstrates the feasibility and effectiveness of the proposed method.

  6. Theory analysis and system identification methods on thermal dynamics characteristics of ballscrews

    Institute of Scientific and Technical Information of China (English)

    Junyong XIA; Youmin HU; Bo WU; Tielin SHI

    2008-01-01

    Empirical model of machine tools on thermal error has been widely researched, which can compensate for thermal error to some extent but not suitable for ther-mal dynamic errors produced by dynamic heat sources. The thermoelastic phenomenon of unidimensional heat transfer of ballscrews influenced by changeable heat sources is analyzed based on the theory of heat transfer. Two methods for system identification (the least square system identification and BP artificial neural network (ANN) system identification) are put forward to establish a dynamic characteristic model of thermal deformation of ballscrews. The model of thermal error of the X axis in a feed system of DM4600 vertical miller is established with a fine identification effect. Comparing the results of the two identification methods, the BP ANN system identification is more precise than the least square system identification.

  7. 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.

  8. Characteristic Dynamic Enhancement Pattern of Magnetic Resonance Imaging for Malignant Thyroid Tumor: A Preliminary Report

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young Nam; Hwang, Hee Young; Shim, Young Sup; Byun, Sung Su; Choi, Hye Young; Kim, Hyung Sik [Dept. of Radiology, Gil Hospital, Gachon University College of Medicine and Science, Incheon (Korea, Republic of)

    2011-11-15

    The purpose of this study is to determine the characteristic dynamic enhancement pattern of magnetic resonance (MR) imaging for malignant thyroid tumor. Eight patients who were pathology proven to have a malignant thyroid tumor, preoperatively. There are 5 papillary carcinomas, 1 medullary carcinoma, 1 follicular carcinoma, and 1 fine needle aspiration biopsy proven atypical cell. Based on preoperative MR imaging, we compared the dynamic MR enhancement pattern relating to the pathologic type. On contrast agent-enhanced dynamic T1-weighted image (T1WI), 5 papillary carcinoma and one medullary carcinoma showed delayed enhancement compared to normal parenchyma. In addition, one follicular carcinoma shows stronger enhancement than normal parenchyma, with one papillary carcinoma showing a persistent decrease in enhancement compared to normal parenchyma. Although this study is limited by a small patients population, the data suggests that delayed enhancement on enhanced dynamic T1WI is a possible characteristic MR finding of a malignant thyroid tumor. I think that the comparison of MR imaging between benign and malignant nodules is required for a correct characterization.

  9. Methane dynamics regulated by microbial community response to permafrost thaw.

    Science.gov (United States)

    McCalley, Carmody K; Woodcroft, Ben J; Hodgkins, Suzanne B; Wehr, Richard A; Kim, Eun-Hae; Mondav, Rhiannon; Crill, Patrick M; Chanton, Jeffrey P; Rich, Virginia I; Tyson, Gene W; Saleska, Scott R

    2014-10-23

    Permafrost contains about 50% of the global soil carbon. It is thought that the thawing of permafrost can lead to a loss of soil carbon in the form of methane and carbon dioxide emissions. The magnitude of the resulting positive climate feedback of such greenhouse gas emissions is still unknown and may to a large extent depend on the poorly understood role of microbial community composition in regulating the metabolic processes that drive such ecosystem-scale greenhouse gas fluxes. Here we show that changes in vegetation and increasing methane emissions with permafrost thaw are associated with a switch from hydrogenotrophic to partly acetoclastic methanogenesis, resulting in a large shift in the δ(13)C signature (10-15‰) of emitted methane. We used a natural landscape gradient of permafrost thaw in northern Sweden as a model to investigate the role of microbial communities in regulating methane cycling, and to test whether a knowledge of community dynamics could improve predictions of carbon emissions under loss of permafrost. Abundance of the methanogen Candidatus 'Methanoflorens stordalenmirensis' is a key predictor of the shifts in methane isotopes, which in turn predicts the proportions of carbon emitted as methane and as carbon dioxide, an important factor for simulating the climate feedback associated with permafrost thaw in global models. By showing that the abundance of key microbial lineages can be used to predict atmospherically relevant patterns in methane isotopes and the proportion of carbon metabolized to methane during permafrost thaw, we establish a basis for scaling changing microbial communities to ecosystem isotope dynamics. Our findings indicate that microbial ecology may be important in ecosystem-scale responses to global change.

  10. AN ITEM RESPONSE MODEL WITH SINGLE PEAKED ITEM CHARACTERISTIC CURVES - THE PARELLA MODEL

    NARCIS (Netherlands)

    HOIJTINK, H; MOLENAAR, [No Value

    In this paper an item response model (the PARELLA model) designed specifically for the measurement of attitudes and preferences will be introduced. In contrast with the item response models currently used (e.g. the Rasch model and, the two and three parameter logistic model) the item characteristic

  11. Effects of housing and individual coping characteristics in immune responses of pigs

    NARCIS (Netherlands)

    Bolhuis, J.E.; Parmentier, H.K.; Schouten, W.G.P.; Schrama, J.W.; Wiegant, V.M.

    2003-01-01

    The impact of environmental factors on immune responses may be influenced by coping characteristics of the individuals under study. The behavioral response of pigs in a so-called Backrest early in life seems indicative of their coping style at a later age. The present study investigated the effects

  12. Experimental damage detection of cracked beams by using nonlinear characteristics of forced response

    Science.gov (United States)

    Andreaus, U.; Baragatti, P.

    2012-08-01

    Experimental evaluation of the flexural forced vibrations of a steel cantilever beam having a transverse surface crack extending uniformly along the width of the beam was performed, where an actual fatigue crack was introduced instead - as usual - of a narrow slot. The nonlinear aspects of the dynamic response of the beam under harmonic excitation were considered and the relevant quantitative parameters were evaluated, in order to relate the nonlinear resonances to the presence and size of the crack. To this end, the existence of sub- and super-harmonic components in the Fourier spectra of the acceleration signals was evidenced, and their amplitudes were quantified. In particular, the acceleration signals were measured in different positions along the beam axis and under different forcing levels at the beam tip. The remarkable relevance of the above mentioned nonlinear characteristics, and their substantial independence on force magnitude and measurement point were worthily noted in comparison with the behavior of the intact beam. Thus, a reliable method of damage detection was proposed which was based on simple tests requiring only harmonically forcing and acceleration measuring in any point non-necessarily near the crack. Then, the time-history of the acceleration recorded at the beam tip was numerically processed in order to obtain the time-histories of velocity and displacement. The nonlinear features of the forced response were described and given a physical interpretation in order to define parameters suitable for damage detection. The efficiency of such parameters was discussed with respect to the their capability of detecting damage and a procedure for damage detection was proposed which was able to detect even small cracks by using simple instruments. A finite element model of the cantilever beam was finally assembled and tuned in order to numerically simulate the results of the experimental tests.

  13. Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts

    Science.gov (United States)

    Shaobin, H.; Enyuan, W.; Xiaofei, L.

    2014-04-01

    Dynamic collapses of deeply mined coal rocks are severe threats to miners, in order to predict the collapses more accurately using electromagnetic radiation (EMR), we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials and energy with its environment and gradually transits from its original stable equilibrium structure to a non-equilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolutions process, the dissipated energy caused by damage evolutions such as crack propagation, fractal sliding and shearing can be regarded as the fingerprint of various EMR micro-mechanics. Dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures) and temporal (dynamic evolution) characteristics of coal rocks, and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to in-depth understand EMR mechanism and to increase the accuracy of applying the EMR method to forecast dynamic disasters.

  14. Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts

    Science.gov (United States)

    Hu, S.; Wang, E.; Liu, X.

    2014-08-01

    Dynamic collapses of deeply mined coal rocks are severe threats to miners; in order to predict collapses more accurately using electromagnetic radiation (EMR), we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials (gas, water and coal) and energy with its environment and gradually transitions from its original stable equilibrium structure to a nonequilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolution processes. Moreover, the dissipated energy caused by the damage evolutions, such as crack propagation, fractal sliding and shearing, can be regarded as the fingerprint of various EMR micro-mechanics. The dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures) and temporal (dynamic evolution) characteristics of coal rocks and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to understand the EMR mechanism in detail and to increase the accuracy of the EMR method in forecasting dynamic disasters.

  15. Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts

    Directory of Open Access Journals (Sweden)

    H. Shaobin

    2014-04-01

    Full Text Available Dynamic collapses of deeply mined coal rocks are severe threats to miners, in order to predict the collapses more accurately using electromagnetic radiation (EMR, we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials and energy with its environment and gradually transits from its original stable equilibrium structure to a non-equilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolutions process, the dissipated energy caused by damage evolutions such as crack propagation, fractal sliding and shearing can be regarded as the fingerprint of various EMR micro-mechanics. Dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures and temporal (dynamic evolution characteristics of coal rocks, and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to in-depth understand EMR mechanism and to increase the accuracy of applying the EMR method to forecast dynamic disasters.

  16. Investigation of Dynamic Mechanical Behavior and Damage Characteristics in TC32 Alloy

    Directory of Open Access Journals (Sweden)

    LI Mingbing

    2016-10-01

    Full Text Available The dynamic shearing experiment was been done by using split Hopkinson pressure bar(SHPB technique in TC32 alloy with lamellar, bimodal and basket microstructures. The damage Characteristics of TC32 alloy was investigated by using optical microscope(OP and scanning electron microscopy(SEM. The results show that the critical fracture velocity is 2400 s-1, 2700 s-1, and 2600 s-1 for lamellar, bimodal, and basket microstructures respectively. The bimodal microstructure exhibit the best Dynamic mechanical behavior compared with the other two microstructures. Adiabatic shear bands(ASBs and microvoids initiation, growth, and coalescence to damage in adiabatic shear bands(ASBs were observed in all of three microstructures. Also, microvoids initiation and growth are prior to the interface between ASBs and matrix. Investigation indicated that plastic flow characteristic is not obvious at the interface between ASBs and matrix, which observed long crack in lamellar microstructure. In bimodal microstructure, fibrous a adiabatic shear bands(ASBs and surrounding region are shown. Because of strong shear deformation, the plastic flow characteristic appears clearly, and primary α phase was elongated. Microvoids initiation is also prior to the α/β phase boundaries. The damage characteristics of basket microstructure are similar to bimodal microstructure. But unlike lamellar and basket microstructures, the microvoids are initiatied when the acicular primary α phase arranged in order is perpendicular to the adiabatic shear bands(ASBs in lamellar microstructure. ASBs is mostly consisted of equiaxed grains, and the deformation mechanism still wasn't defined.

  17. Manufacturing Error Effects on Mechanical Properties and Dynamic Characteristics of Rotor Parts under High Acceleration

    Science.gov (United States)

    Jia, Mei-Hui; Wang, Cheng-Lin; Ren, Bin

    2017-07-01

    Stress, strain and vibration characteristics of rotor parts should be changed significantly under high acceleration, manufacturing error is one of the most important reason. However, current research on this problem has not been carried out. A rotor with an acceleration of 150,000 g is considered as the objective, the effects of manufacturing errors on rotor mechanical properties and dynamic characteristics are executed by the selection of the key affecting factors. Through the force balance equation of the rotor infinitesimal unit establishment, a theoretical model of stress calculation based on slice method is proposed and established, a formula for the rotor stress at any point derives. A finite element model (FEM) of rotor with holes is established with manufacturing errors. The changes of the stresses and strains of a rotor in parallelism and symmetry errors are analyzed, which verify the validity of the theoretical model. The pre-stressing modal analysis is performed based on the aforementioned static analysis. The key dynamic characteristics are analyzed. The results demonstrated that, as the parallelism and symmetry errors increase, the equivalent stresses and strains of the rotor slowly increase linearly, the highest growth rate does not exceed 4%, the maximum change rate of natural frequency is 0.1%. The rotor vibration mode is not significantly affected. The FEM construction method of the rotor with manufacturing errors can be utilized for the quantitative research on rotor characteristics, which will assist in the active control of rotor component reliability under high acceleration.

  18. Response surface methodology for predicting quality characteristics of beef patties added with flaxseed and tomato paste.

    Science.gov (United States)

    Valenzuela Melendres, M; Camou, J P; Torrentera Olivera, N G; Alvarez Almora, E; González Mendoza, D; Avendaño Reyes, L; González Ríos, H

    2014-05-01

    Response surface methodology was used to study the effect of flaxseed flour (FS) and tomato paste (TP) addition, from 0 to 10% and 0 to 20% respectively, on beef patty quality characteristics. The assessed quality characteristics were color (L, a, and b), pH and texture profile analysis (TPA). Also, sensory analysis was performed for the assessment of color, juiciness, firmness, and general acceptance. FS addition reduced L and a values and decreased weight loss of cooked products (Psensory characteristics of the cooked product (Psensory characteristics evaluated had an acceptable score (>5.6). Thus FS and TP are ingredients that can be used in beef patty preparation.

  19. Dynamic Characteristic Analysis of Linear DC Motor by 3D EMCN Considering Input Voltage

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Kyung Ho; Yeom, Sang Bu [Changwon National University, Changwon(Korea); Hong, JUNG Pyo; Hur Jin; Kang Do Hyunc [Hanyang University(Seoul Campus), Seoul(Korea)

    2002-02-01

    In order to design the Linear DC Motor (LDM) With improved characteristics, transient and steady state analysis are required. Furthermore, 3D analysis is also needed to analyze the precise characteristics like thrust, time harmonics. This paper deals with the transient and dynamic characteristic analysis if LDM by coupling of external circuit and motion equation using 3D Equivalent Magnetic Circuit Network Method (EMCN). For the three dimensional analysis of electric machine, EMCN is very effective method that ensures high accuracy similar to FEM and short computation time. Also, The modeling by EMCN easily allows the mover to move with respect to the Sartre at each time Also, and the spatial moving step is determined by the solution of the mechanical motion equation and the computed electromagnetic thrust. The results are compared with experimental ones to clarify the usefulness and verify the accuracy of the proposed method. (author). 11 refs., 20 figs., 2 tabs.

  20. Temporal and spatial dynamical simulation of groundwater characteristics in Minqin Oasis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Application scope of geostatistics has been gradually extended from original geologic field to soil science and ecological field, etc. and its successful application results have been widely demonstrated. But little information is reported as to the direct use of geostatistical method to work out the distribu- tion map of groundwater characteristics. In this paper the semivariogram of geostatistics, in combina- tion with GIS, was used to quantitatively study the spatial variation characteristics of groundwater table depth and mineralization degree and their relation to the landuse changes. F test of the used spherical model reached a very significant level, and the theoretical model can well reflect the spatial structural characteristics of groundwater table depth and mineralization degree and achieve an ideal result. This shows that the application of the method in the dynamical simulation of groundwater is feasible. And this paper also provides useful reference for the application of geostatistics in the study of the dy- namical variations of groundwater resources in the oasis.

  1. Who is responsible for food risks? The influence of risk type and risk characteristics

    DEFF Research Database (Denmark)

    Leikas, Sointu; Lindeman, Marjaana; Roininen, Katariina;

    2009-01-01

    The influence of food risk type and risk characteristics on food risk responsibility judgments was studied. A total of 1270 Finnish consumers judged their personal responsibility and the responsibility of three non-personal targets, industry, retail, and society, in relation to six food......-related risks. They also evaluated the risks on several psychometric dimensions. The ratings were gathered via internet questionnaire. Industry and society were considered to be most responsible for all risks but the risk of cardiovascular disease, for which personal responsibility was considered to be highest....... Judgments of personal controllability predicted personal responsibility judgments, and unnaturalness judgments predicted non-personal targets' judged responsibility. Personal responsibility judgments were related to different risk dimensions than judgments of non-personal targets' responsibility....

  2. Studying Climate Response to Forcing by the Nonlinear Dynamical Mode Decomposition

    Science.gov (United States)

    Mukhin, Dmitry; Gavrilov, Andrey; Loskutov, Evgeny; Feigin, Alexander

    2017-04-01

    An analysis of global climate response to external forcing, both anthropogenic (mainly, CO2 and aerosol) and natural (solar and volcanic), is needed for adequate predictions of global climate change. Being complex dynamical system, the climate reacts to external perturbations exciting feedbacks (both positive and negative) making the response non-trivial and poorly predictable. Thus an extraction of internal modes of climate system, investigation of their interaction with external forcings and further modeling and forecast of their dynamics, are all the problems providing the success of climate modeling. In the report the new method for principal mode extraction from climate data is presented. The method is based on the Nonlinear Dynamical Mode (NDM) expansion [1,2], but takes into account a number of external forcings applied to the system. Each NDM is represented by hidden time series governing the observed variability, which, together with external forcing time series, are mapped onto data space. While forcing time series are considered to be known, the hidden unknown signals underlying the internal climate dynamics are extracted from observed data by the suggested method. In particular, it gives us an opportunity to study the evolution of principal system's mode structure in changing external conditions and separate the internal climate variability from trends forced by external perturbations. Furthermore, the modes so obtained can be extrapolated beyond the observational time series, and long-term prognosis of modes' structure including characteristics of interconnections and responses to external perturbations, can be carried out. In this work the method is used for reconstructing and studying the principal modes of climate variability on inter-annual and decadal time scales accounting the external forcings such as anthropogenic emissions, variations of the solar activity and volcanic activity. The structure of the obtained modes as well as their response to

  3. Dynamics of lithium ions in borotellurite mixed former glasses: Correlation between the characteristic length scales of mobile ions and glass network structural units

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, A.; Ghosh, A., E-mail: sspag@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2014-10-28

    We have studied the mixed network former effect on the dynamics of lithium ions in borotellurite glasses in wide composition and temperature ranges. The length scales of ion dynamics, such as characteristic mean square displacement and spatial extent of sub-diffusive motion of lithium ions have been determined from the ac conductivity and dielectric spectra, respectively, in the framework of linear response theory. The relative concentrations of different network structural units have been determined from the deconvolution of the FTIR spectra. A direct correlation between the ion dynamics and the characteristic length scales and the relative concentration of BO{sub 4} units has been established for different compositions of the borotellurite glasses.

  4. Lateral static and dynamic characteristics of thin-walled box girder

    Institute of Scientific and Technical Information of China (English)

    CAN Yan-an; ZHOU Guang-chun

    2009-01-01

    To analyze the static and dynamic behaviors of the thin-walled box girder in its lateral webs in consideration of shear lag effect and shear deformation, an approach based on the minimum potential principle is introduced in this paper. Both static and dynamic response equations as well as the corresponding natural boundary conditions of the box girder are deduced. Meanwhile, three generalized displacement functions:w(x), U(x) and 0(x) are employed and their differences in the calculus of variation are quantitatively investigated. The comparison of finite shell element results with analytical results of calculation examples validates the feasibility of the proposed approach.

  5. Dynamic Characteristics of a Hydraulic Amplification Mechanism for Large Displacement Actuators Systems

    Directory of Open Access Journals (Sweden)

    Xavier Arouette

    2010-03-01

    Full Text Available We have developed a hydraulic displacement amplification mechanism (HDAM and studied its dynamic response when combined with a piezoelectric actuator. The HDAM consists of an incompressible fluid sealed in a microcavity by two largely deformable polydimethylsiloxane (PDMS membranes. The geometry with input and output surfaces having different cross-sectional areas creates amplification. By combining the HDAM with micro-actuators, we can amplify the input displacement generated by the actuators, which is useful for applications requiring large deformation, such as tactile displays. We achieved a mechanism offering up to 18-fold displacement amplification for static actuation and 12-fold for 55 Hz dynamic actuation.

  6. Dynamics of the microbiota in response to host infection.

    Directory of Open Access Journals (Sweden)

    Clara Belzer

    Full Text Available Longitudinal studies of the microbiota are important for discovering changes in microbial communities that affect the host. The complexity of these ecosystems requires rigorous integrated experimental and computational methods to identify temporal signatures that promote physiologic or pathophysiologic responses in vivo. Employing a murine model of infectious colitis with the pathogen Citrobacter rodentium, we generated a 2-month time-series of 16S rDNA gene profiles, and quantitatively cultured commensals, from multiple intestinal sites in infected and uninfected mice. We developed a computational framework to discover time-varying signatures for individual taxa, and to automatically group signatures to identify microbial sub-communities within the larger gut ecosystem that demonstrate common behaviors. Application of this model to the 16S rDNA dataset revealed dynamic alterations in the microbiota at multiple levels of resolution, from effects on systems-level metrics to changes across anatomic sites for individual taxa and species. These analyses revealed unique, time-dependent microbial signatures associated with host responses at different stages of colitis. Signatures included a Mucispirillum OTU associated with early disruption of the colonic surface mucus layer, prior to the onset of symptomatic colitis, and members of the Clostridiales and Lactobacillales that increased with successful resolution of inflammation, after clearance of the pathogen. Quantitative culture data validated findings for predominant species, further refining and strengthening model predictions. These findings provide new insights into the complex behaviors found within host ecosystems, and define several time-dependent microbial signatures that may be leveraged in studies of other infectious or inflammatory conditions.

  7. DYNAMIC CHARACTERISTIC ANALYSIS OF FUZZY- STOCHASTIC TRUSS STRUCTURES BASED ON FUZZY FACTOR METHOD AND RANDOM FACTOR METHOD

    Institute of Scientific and Technical Information of China (English)

    MA Juan; CHEN Jian-jun; XU Ya-lan; JIANG Tao

    2006-01-01

    A new fuzzy stochastic finite element method based on the fuzzy factor method and random factor method is given and the analysis of structural dynamic characteristic for fuzzy stochastic truss structures is presented. Considering the fuzzy randomness of the structural physical parameters and geometric dimensions simultaneously, the structural stiffness and mass matrices are constructed based on the fuzzy factor method and random factor method; from the Rayleigh's quotient of structural vibration, the structural fuzzy random dynamic characteristic is obtained by means of the interval arithmetic;the fuzzy numeric characteristics of dynamic characteristic are then derived by using the random variable's moment function method and algebra synthesis method. Two examples are used to illustrate the validity and rationality of the method given. The advantage of this method is that the effect of the fuzzy randomness of one of the structural parameters on the fuzzy randomness of the dynamic characteristic can be reflected expediently and objectively.

  8. LVP modeling and dynamic characteristics prediction of a hydraulic power unit in deep-sea

    Science.gov (United States)

    Cao, Xue-peng; Ye, Min; Deng, Bin; Zhang, Cui-hong; Yu, Zu-ying

    2013-03-01

    A hydraulic power unit (HPU) is the driving "heart" of deep-sea working equipment. It is critical to predict its dynamic performances in deep-water before being immerged in the seawater, while the experimental tests by simulating deep-sea environment have many disadvantages, such as expensive cost, long test cycles, and difficult to achieve low-temperature simulation, which is only used as a supplementary means for confirmatory experiment. This paper proposes a novel theoretical approach based on the linear varying parameters (LVP) modeling to foresee the dynamic performances of the driving unit. Firstly, based on the varying environment features, dynamic expressions of the compressibility and viscosity of hydraulic oil are derived to reveal the fluid performances changing. Secondly, models of hydraulic system and electrical system are accomplished respectively through studying the control process and energy transfer, and then LVP models of the pressure and flow rate control is obtained through the electro-hydraulic models integration. Thirdly, dynamic characteristics of HPU are obtained by the model simulating within bounded closed sets of varying parameters. Finally, the developed HPU is tested in a deep-sea imitating hull, and the experimental results are well consistent with the theoretical analysis outcomes, which clearly declare that the LVP modeling is a rational way to foresee dynamic performances of HPU. The research approach and model analysis results can be applied to the predictions of working properties and product designs for other deep-sea hydraulic pump.

  9. 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.

  10. Non-linear dynamic characteristics and optimal control of giant magnetostrictive film subjected to in-plane stochastic excitation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Z. W., E-mail: zhuzhiwen@tju.edu.cn [Department of Mechanics, Tianjin University, 300072, Tianjin (China); Tianjin Key Laboratory of Non-linear Dynamics and Chaos Control, 300072, Tianjin (China); Zhang, W. D., E-mail: zhangwenditju@126.com; Xu, J., E-mail: xujia-ld@163.com [Department of Mechanics, Tianjin University, 300072, Tianjin (China)

    2014-03-15

    The non-linear dynamic characteristics and optimal control of a giant magnetostrictive film (GMF) subjected to in-plane stochastic excitation were studied. Non-linear differential items were introduced to interpret the hysteretic phenomena of the GMF, and the non-linear dynamic model of the GMF subjected to in-plane stochastic excitation was developed. The stochastic stability was analysed, and the probability density function was obtained. The condition of stochastic Hopf bifurcation and noise-induced chaotic response were determined, and the fractal boundary of the system's safe basin was provided. The reliability function was solved from the backward Kolmogorov equation, and an optimal control strategy was proposed in the stochastic dynamic programming method. Numerical simulation shows that the system stability varies with the parameters, and stochastic Hopf bifurcation and chaos appear in the process; the area of the safe basin decreases when the noise intensifies, and the boundary of the safe basin becomes fractal; the system reliability improved through stochastic optimal control. Finally, the theoretical and numerical results were proved by experiments. The results are helpful in the engineering applications of GMF.

  11. Examining flow-flame interaction and the characteristic stretch rate in vortex-driven combustion dynamics using PIV and numerical simulation

    KAUST Repository

    Hong, Seunghyuck

    2013-08-01

    In this paper, we experimentally investigate the combustion dynamics in lean premixed flames in a laboratory scale backward-facing step combustor in which flame-vortex driven dynamics are observed. A series of tests was conducted using propane/hydrogen/air mixtures for various mixture compositions at the inlet temperature ranging from 300K to 500K and at atmospheric pressure. Pressure measurements and high speed particle image velocimetry (PIV) are used to generate pressure response curves and phase-averaged vorticity and streamlines as well as the instantaneous flame front, respectively, which describe unsteady flame and flow dynamics in each operating regime. This work was motivated in part by our earlier study where we showed that the strained flame consumption speed Sc can be used to collapse the pressure response curves over a wide range of operating conditions. In previous studies, the stretch rate at which Sc was computed was determined by trial and error. In this study, flame stretch is estimated using the instantaneous flame front and velocity field from the PIV measurement. Independently, we also use computed strained flame speed and the experimental data to determine the characteristic values of stretch rate near the mode transition points at which the flame configuration changes. We show that a common value of the characteristic stretch rate exists across all the flame configurations. The consumption speed computed at the characteristic stretch rate captures the impact of different operating parameters on the combustor dynamics. These results suggest that the unsteady interactions between the turbulent flow and the flame dynamics can be encapsulated in the characteristic stretch rate, which governs the critical flame speed at the mode transitions and thereby plays an important role in determining the stability characteristics of the combustor. © 2013 The Combustion Institute.

  12. Contrasting Public Opinion Dynamics and Emotional Response during Crisis

    Energy Technology Data Exchange (ETDEWEB)

    Volkova, Svitlana; Chetviorkin, Ilia; Arendt, Dustin L.; Van Durme, Ben

    2016-11-15

    We propose an approach for contrasting spatiotemporal dynamics of public opinions expressed toward targeted entities, also known as stance detection task, in Russia and Ukraine during crisis. Our analysis relies on a novel corpus constructed from posts on the VKontakte social network, centered on local public opinion of the ongoing Russian-Ukrainian crisis, along with newly annotated resources for predicting expressions of fine-grained emotions including joy, sadness, disgust, anger, surprise and fear. Akin to prior work on sentiment analysis we align traditional public opinion polls with aggregated automatic predictions of sentiments for contrastive geo-locations. We report interesting observations on emotional response and stance variations across geo-locations. Some of our findings contradict stereotypical misconceptions imposed by media, for example, we found posts from Ukraine that do not support Euromaidan but support Putin, and posts from Russia that are against Putin but in favor USA. Furthermore, we are the first to demonstrate contrastive stance variations over time across geo-locations using storyline visualization technique.

  13. Estimation of the Rotational Terms of the Dynamic Response Matrix

    Directory of Open Access Journals (Sweden)

    D. Montalvão

    2004-01-01

    Full Text Available The dynamic response of a structure can be described by both its translational and rotational receptances. The latter ones are frequently not considered because of the difficulties in applying a pure moment excitation or in measuring rotations. However, in general, this implies a reduction up to 75% of the complete model. On the other hand, if a modification includes a rotational inertia, the rotational receptances of the unmodified system are needed. In one method, more commonly found in the literature, a so called T-block is attached to the structure. Then, a force, applied to an arm of the T-block, generates a moment together with a force at the connection point. The T-block also allows for angular displacement measurements. Nevertheless, the results are often not quite satisfactory. In this work, an alternative method based upon coupling techniques is developed, in which rotational receptances are estimated without the need of applying a moment excitation. This is accomplished by introducing a rotational inertia modification when rotating the T-block. The force is then applied in its centroid. Several numerical and experimental examples are discussed so that the methodology can be clearly described. The advantages and limitations are identified within the practical application of the method.

  14. Spatially dispersive dynamical response of hot carriers in doped graphene

    Science.gov (United States)

    Kukhtaruk, S. M.; Kochelap, V. A.; Sokolov, V. N.; Kim, K. W.

    2016-05-01

    We study theoretically wave-vector and frequency dispersion of the complex dynamic conductivity tensor (DCT), σlm(k , ω), of doped monolayer graphene under a strong dc electric field. For a general analysis, we consider the weak ac field of arbitrary configuration given by two independent vectors, the ac field polarization and the wave vector k. The high-field transport and linear response to the ac field are described on the base of the Boltzmann kinetic equation. We show that the real part of DCT, calculated in the collisionless regime, is not zero due to dissipation of the ac wave, whose energy is absorbed by the resonant Dirac quasiparticles effectively interacting with the wave. The role of the kinematic resonance at ω =vF | k | (vF is the Fermi velocity) is studied in detail taking into account deviation from the linear energy spectrum and screening by the charge carriers. The isopower-density curves and distributions of angle between the ac current density and field vectors are presented as a map which provides clear graphic representation of the DCT anisotropy. Also, the map shows certain ac field configurations corresponding to a negative power density, thereby it indicates regions of terahertz frequency for possible electrical (drift) instability in the graphene system.

  15. Dynamical Tidal Response of a Rotating Neutron Star

    Science.gov (United States)

    Landry, Philippe; Poisson, Eric

    2017-01-01

    The gravitational wave phase of a neutron star (NS) binary is sensitive to the deformation of the NS that results from its companion's tidal influence. In a perturbative treatment, the tidal deformation can be characterized by a set of dimensionless constants, called Love numbers, which depend on the NS equation of state. For static NSs, one type of Love number encodes the response to gravitoelectric tidal fields (associated with mass multipole moments), while another does likewise for gravitomagnetic fields (associated with mass currents). A NS subject to a gravitomagnetic tidal field develops internal fluid motions through gravitomagnetic induction; the fluid motions are irrotational, provided the star is non-rotating. When the NS is allowed to rotate, the situation is complicated by couplings between the tidal field and the star's spin. The problem becomes tractable in the slow-rotation limit. In this case, the fluid motions induced by an external gravitomagnetic field are fully dynamical, even if the tidal field is stationary: interior metric and fluid variables are time-dependent, and vary on the timescale of the rotation period. Remarkably, the exterior geometry of the NS remains time-independent.

  16. Dynamic response of a vehicle with planar suspension system (PSS) under differential braking

    Science.gov (United States)

    Zhu, Jian Jun; Khajepour, Amir; Esmailzadeh, Ebrahim

    2012-01-01

    To absorb the vibrations and shocks caused by road obstacles effectively in any direction within the wheel rotation plane, a planar suspension system (PSS), in which there are spring-damper struts in both the vertical and longitudinal directions, is proposed to improve the ride quality of a vehicle with such novel suspension systems. The longitudinal spring-damper strut in a PSS is considerably soft compared with the longitudinal connection in a conventional suspension. Consequently, the wheels in a vehicle with PSS can move forth and back with respect to the body. The dynamic behaviours of a PSS vehicle under some special conditions, such as a differential braking in which the braking torque applied to the wheels at two sides of an axle are uneven, may exhibit special characteristics. The directional stability of the PSS vehicle in such a case may be one of the major concerns. The dynamic performance of the PSS vehicle in the differential braking condition is thus necessary to be investigated. This paper presents the investigation results of the transient response of a vehicle with the PSS in such a case. The simulation results are also compared with those of a similar vehicle with conventional suspensions. The study demonstrates that the PSS vehicle is directionally stable in differential braking conditions. The dynamic behaviour of the PSS vehicle is generally comparable with that of a conventional vehicle.

  17. Experimental determination of dynamic characteristics of the VentrAssist implantable rotary blood pump.

    Science.gov (United States)

    Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Qian, Yi

    2004-12-01

    The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump consists of a shaftless impeller, which also acts as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, which result from the small clearances between the outside surfaces of the impeller and the pump cavity. These small clearances range from approximately 50 microm to 230 microm in size in the version of pump reported here. This article presents experimental investigation into the dynamic characteristics of the impeller-bearing-pump housing system of the rotary blood pump for increasing pump speeds at different flow rates. The pump was mounted on a suspension system consisting of a platform and springs, where the natural frequency and damping ratio for the suspension system were determined. Real-time measurements of the impeller's displacement were performed using Hall effect sensors. A vertical disturbance force was exerted onto the pump housing, causing the impeller to be displaced in vertical direction from its dynamic equilibrium position within the pump cavity. The impeller displacement was represented by a decaying sine wave, which indicated the impeller restoring to its equilibrium position. From the decaying sine wave the natural frequency and stiffness coefficient of the system were determined. Furthermore, the logarithmic decrement method was used to determine the damping ratio and eventually the damping coefficient of the system. Results indicate that stiffness and damping coefficients increased as flow rate and pump speed increased, representing an increase in stability with these changing conditions. However, pump speed had a greater influence on the stiffness and damping coefficients than flow rate did, which was evident through dynamic analysis. Overall the experimental method presented in this

  18. Adsorption effect on the dynamic response of a biochemical reaction in a biofilm reactor for wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tsuneda, S.; Inoue, Y.; Auresenia, J.; Hirata, A. [Department of Chemical Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2003-09-01

    The dynamic behavior of a completely mixed, three-phase, fluidized bed biofilm reactor treating simulated domestic wastewater was studied with step changes in inlet concentration. It was found that the response curves showed second order characteristics, i.e., as the inlet concentration was increased, the outlet concentration also increased, reached a peak value and then decreased until it leveled to a new steady-state value corresponding to the new inlet concentration level. Nonlinear regression analysis was performed using Monod-type rate equations with and without an adsorption term. As a result, the theoretical curve of the kinetic model that incorporates the adsorption term has best fit to the actual response in most cases. Thus, it was concluded that the adsorption of a substrate onto the biofilm and carrier particles has a significant effect on the dynamic response in biofilm processes. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  19. Field Measurement-Based System Identification and Dynamic Response Prediction of a Unique MIT Building.

    Science.gov (United States)

    Cha, Young-Jin; Trocha, Peter; Büyüköztürk, Oral

    2016-07-01

    Tall buildings are ubiquitous in major cities and house the homes and workplaces of many individuals. However, relatively few studies have been carried out to study the dynamic characteristics of tall buildings based on field measurements. In this paper, the dynamic behavior of the Green Building, a unique 21-story tall structure located on the campus of the Massachusetts Institute of Technology (MIT, Cambridge, MA, USA), was characterized and modeled as a simplified lumped-mass beam model (SLMM), using data from a network of accelerometers. The accelerometer network was used to record structural responses due to ambient vibrations, blast loading, and the October 16th 2012 earthquake near Hollis Center (ME, USA). Spectral and signal coherence analysis of the collected data was used to identify natural frequencies, modes, foundation rocking behavior, and structural asymmetries. A relation between foundation rocking and structural natural frequencies was also found. Natural frequencies and structural acceleration from the field measurements were compared with those predicted by the SLMM which was updated by inverse solving based on advanced multiobjective optimization methods using the measured structural responses and found to have good agreement.

  20. Analysis of Dynamic Response of Explosive Disposal Robot to Rough Road Excitation

    Institute of Scientific and Technical Information of China (English)

    MO Haijun; HUANG Ping; HU Qingchun; DUAN Fuhai

    2006-01-01

    When the explosive disposal robot traveling over a rough road, it will shake up and down, and generates dynamic loads. Furthermore, the jolt of the explosive disposal robot will result in oscillation and large inertia forces of the explosive, and will effect the stability of the grasped explosive, even cause the explosive slipping from the claw and falling to the ground, which seriously threats the safety of the robot and around environment. A tracked explosive disposal robot has been developed at South China University of Technology. This paper takes the explosive disposal robot and the grasped explosive as study object. Especially focuses on the response analysis of the grasped explosive when the robot traveling over a rough road. Analyzing the vibration characteristic of the explosive and the effects of the robot moving speeds on the stability of the explosive. The dynamic response of the explosive is obtained by simulation, the results show that the velocity of the robot is a sensitivity influence factor on the oscillation of grasped explosive.

  1. Field Measurement-Based System Identification and Dynamic Response Prediction of a Unique MIT Building

    Directory of Open Access Journals (Sweden)

    Young-Jin Cha

    2016-07-01

    Full Text Available Tall buildings are ubiquitous in major cities and house the homes and workplaces of many individuals. However, relatively few studies have been carried out to study the dynamic characteristics of tall buildings based on field measurements. In this paper, the dynamic behavior of the Green Building, a unique 21-story tall structure located on the campus of the Massachusetts Institute of Technology (MIT, Cambridge, MA, USA, was characterized and modeled as a simplified lumped-mass beam model (SLMM, using data from a network of accelerometers. The accelerometer network was used to record structural responses due to ambient vibrations, blast loading, and the October 16th 2012 earthquake near Hollis Center (ME, USA. Spectral and signal coherence analysis of the collected data was used to identify natural frequencies, modes, foundation rocking behavior, and structural asymmetries. A relation between foundation rocking and structural natural frequencies was also found. Natural frequencies and structural acceleration from the field measurements were compared with those predicted by the SLMM which was updated by inverse solving based on advanced multiobjective optimization methods using the measured structural responses and found to have good agreement.

  2. CERN antiproton target: Hydrocode analysis of its core material dynamic response under proton beam impact

    Science.gov (United States)

    Martin, Claudio Torregrosa; Perillo-Marcone, Antonio; Calviani, Marco; Muñoz-Cobo, José-Luis

    2016-07-01

    Antiprotons are produced at CERN by colliding a 26 GeV /c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 °C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of end-of-pulse tensile waves and its relevance on the overall response (iii) A reduction of 44% in tensile pressure could be obtained by the use of a high density tantalum cladding.

  3. The decay of Redox-stress Response Capacity is a substantive characteristic of aging: Revising the redox theory of aging.

    Science.gov (United States)

    Meng, Jiao; Lv, Zhenyu; Qiao, Xinhua; Li, Xiaopeng; Li, Yazi; Zhang, Yuying; Chen, Chang

    2017-04-01

    Aging is tightly associated with redox events. The free radical theory of aging indicates that redox imbalance may be an important factor in the aging process. Most studies about redox and aging focused on the static status of oxidative stress levels, there has been little research investigating differential responses to redox challenge during aging. In this study, we used Caenorhabditis elegans and human fibroblasts as models to compare differential responses to oxidative stress challenge in young and old individuals. In response to paraquat stress, young individuals generated more ROS and activated signaling pathways including p-ERK, p-AKT and p-AMPKα/β. After the initial response, young individuals then promoted NRF2 translocation and induced additional antioxidant enzymes and higher expression of phase II enzymes, including SOD, CAT, GPX, HO-1, GSTP-1and others, to maintain redox homeostasis. Moreover, young individuals also demonstrated a better ability to degrade damaged proteins by up-regulating the expression of chaperones and improving proteasome activity. Based on these data, we propose a new concept "Redox-stress Response Capacity (RRC)", which suggests cells or organisms are capable of generating dynamic redox responses to activate cellular signaling and maintain cellular homeostasis. The decay of RRC is the substantive characteristic of aging, which gives a new understand of the redox theory of aging. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  4. Elastic-plastic contact force history and response characteristics of circular plate subjected to impact by a projectile

    Institute of Scientific and Technical Information of China (English)

    L. B. Chen; F. Xi; J. L. Yang

    2007-01-01

    A new elastic-plastic impact-contact model is proposed in this paper. By adopting the principle of minimum acceleration for elastic-plastic continue at finite deformation,and with the aid of finite difference method, the proposed model is applied in the problem of dynamic response of a clamped thin circular plate subjected to a projectile impact centrally. The impact force history and response characte-ristics of the target plate is studied in detail. The theoreti-cal predictions of the impact force and plate deflection are in good agreements with those of LDA experimental data.Linear expressions of the maximum impact force/transverse deflection versus impact velocity are given on the basis of the theoretical results.

  5. Analysis of structural dynamic characteristics of a high speed light special catamaran

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper,structural dynamic characteristics of a high-speed light special catamaran-wave piercing catamaran are analyzed using the FEA software MSC-NASTRAN.The dynamic reduction method is introduced to eliminate the local vibration modes in order to obtain the whole ship's mode shapes.In the post-processor,a lot of accessorial methods are adopted to eliminate the local vibrations,so that the whole ship's mode shapes can be identified.The modal analysis indicates that the dynamic reduction method fits for mode shapes identifying.In the end,the test results of a catamaran named Frederick G.Greed are used for reference to validate the obtained results.The comparison process shows that the results are credible.A special mode shape,which is quite different with that of conventional monohull ship,is also pointed out.The obtained results provide a valuable reference for the coming computation of catamaran's vibration characteristics.

  6. 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.

  7. 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.

  8. Non-pneumatic mechanical elastic wheel natural dynamic characteristics and influencing factors

    Institute of Scientific and Technical Information of China (English)

    ZHAO You-qun; ZANG Li-guo; CHEN Yue-qiao; LI Bo; WANG Jian

    2015-01-01

    Non-pneumatic tire appears to have advantages over traditional pneumatic tire in terms of flat proof and maintenance free. A mechanical elastic wheel (MEW) with a non-pneumatic elastic outer ring which functions as air of pneumatic tire was presented. The structure of MEW was non-inflatable integrated configuration and the effect of hinges was accounted for only in tension. To establish finite element model of MEW, various nonlinear factors, such as geometrical nonlinearity, material nonlinearity and contact nonlinearity, were considered. Load characteristic test was conducted by tyre dynamic test-bed to obtain force-deflection curve. And the finite element model was validated through load characteristic test. Natural dynamic characteristics of the MEW and its influencing factors were investigated based on the finite element model. Simulation results show that the finite element model closely matched experimental wheel. The results also show that natural frequency is related to ground constraints, material properties, loads and torques. Influencing factors as above obviously affect the amplitude of mode of vibration, but have little effect on mode of vibration shape. The results can provide guidance for experiment research, structural optimization of MEW.

  9. Dynamical characteristics of surface EMG signals of hand grasps via recurrence plot.

    Science.gov (United States)

    Ouyang, Gaoxiang; Zhu, Xiangyang; Ju, Zhaojie; Liu, Honghai

    2014-01-01

    Recognizing human hand grasp movements through surface electromyogram (sEMG) is a challenging task. In this paper, we investigated nonlinear measures based on recurrence plot, as a tool to evaluate the hidden dynamical characteristics of sEMG during four different hand movements. A series of experimental tests in this study show that the dynamical characteristics of sEMG data with recurrence quantification analysis (RQA) can distinguish different hand grasp movements. Meanwhile, adaptive neuro-fuzzy inference system (ANFIS) is applied to evaluate the performance of the aforementioned measures to identify the grasp movements. The experimental results show that the recognition rate (99.1%) based on the combination of linear and nonlinear measures is much higher than those with only linear measures (93.4%) or nonlinear measures (88.1%). These results suggest that the RQA measures might be a potential tool to reveal the sEMG hidden characteristics of hand grasp movements and an effective supplement for the traditional linear grasp recognition methods.

  10. Characteristics of the Main Journal Bearings of an Engine Based on Non-linear Dynamics

    Institute of Scientific and Technical Information of China (English)

    NI Guangjian; ZHANG Junhong; CHENG Xiaoming

    2009-01-01

    Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.

  11. Analysis of Static and Dynamic Properties of Micromirror with the Application of Response Surface Method

    Directory of Open Access Journals (Sweden)

    A Martowicz

    2016-09-01

    Full Text Available The paper presents the results of an application of response surface method to aid the analysis of variation of static and dynamic properties of micromirror. The multiphysics approach was taken into account to elaborate finite element model of electrostatically actuated microdevice and coupled analyses were carried out to yield the results. Used procedure of metamodel fitting is described and its quality is discussed. Elaborated approximations were used to perform the sensitivity analysis as well as to study the propagation of variation introduced by uncertain and control parameters. The input parameters deal with geometry, material properties and control voltage. As studied output characteristics there were chosen the resultant static vertical displacement of reflecting surfaces and the resonance frequency related to the first normal mode of vibration.

  12. Numerical investigation of amplitude-dependent dynamic response in acoustic metamaterials with nonlinear oscillators.

    Science.gov (United States)

    Manimala, James M; Sun, C T

    2016-06-01

    The amplitude-dependent dynamic response in acoustic metamaterials having nonlinear local oscillator microstructures is studied using numerical simulations on representative discrete mass-spring models. Both cubically nonlinear hardening and softening local oscillator cases are considered. Single frequency, bi-frequency, and wave packet excitations at low and high amplitude levels were used to interrogate the models. The propagation and attenuation characteristics of harmonic waves in a tunable frequency range is found to correspond to the amplitude and nonlinearity-dependent shifts in the local resonance bandgap for such nonlinear acoustic metamaterials. A predominant shift in the propagated wave spectrum towards lower frequencies is observed. Moreover, the feasibility of amplitude and frequency-dependent selective filtering of composite signals consisting of individual frequency components which fall within propagating or attenuating regimes is demonstrated. Further enrichment of these wave manipulation mechanisms in acoustic metamaterials using different combinations of nonlinear microstructures presents device implications for acoustic filters and waveguides.

  13. Dynamic Response of Soft Core Sandwich Beams with Metal-Graphene Nanocomposite Skins

    Directory of Open Access Journals (Sweden)

    M. A. R. Loja

    2017-01-01

    Full Text Available Sandwich structures are able to provide enhanced strength, stiffness, and lightweight characteristics, thus contributing to an improved overall structural response. To this sandwich configuration one may associate through-thickness graded core material properties and homogeneous or graded properties nanocomposite skins. These tailor-made possibilities may provide alternative design solutions to specific problem requisites. This work aims to address these possibilities, considering to this purpose a package of three beam layerwise models based on different shear deformation theories, implemented through Kriging-based finite elements. The viscoelastic behaviour of the sandwich core is modelled using the complex method and the dynamic problem is solved in the frequency domain. A set of case studies illustrates the performance of the models.

  14. A brief history of free-response receiver operating characteristic paradigm data analysis.

    Science.gov (United States)

    Chakraborty, Dev P

    2013-07-01

    In the receiver operating characteristic paradigm the observer assigns a single rating to each image and the location of the perceived abnormality, if any, is ignored. In the free-response receiver operating characteristic paradigm the observer is free to mark and rate as many suspicious regions as are considered clinically reportable. Credit for a correct localization is given only if a mark is sufficiently close to an actual lesion; otherwise, the observer's mark is scored as a location-level false positive. Until fairly recently there existed no accepted method for analyzing the resulting relatively unstructured data containing random numbers of mark-rating pairs per image. This report reviews the history of work in this field, which has now spanned more than five decades. It introduces terminology used to describe the paradigm, proposed measures of performance (figures of merit), ways of visualizing the data (operating characteristics), and software for analyzing free-response receiver operating characteristic studies.

  15. Two-particle response in cluster dynamical mean-field theory: formalism and application to the Raman response of high-temperature superconductors.

    Science.gov (United States)

    Lin, Nan; Gull, Emanuel; Millis, Andrew J

    2012-09-07

    A method is presented for the unbiased numerical computation of two-particle response functions of correlated electron materials via a solution of the dynamical mean-field equations in the presence of a perturbing field. The power of the method is demonstrated via a computation of the Raman B(1g) and B(2g) scattering intensities of the two-dimensional Hubbard model in parameter regimes believed to be relevant to high-temperature superconductivity. The theory reproduces the "two-magnon" peak characteristic of the Raman intensity of insulating parent compounds of high-T(c) copper oxide superconductors, and shows how it evolves to a quasiparticle response, as carriers are added. The method can be applied in any situation where a solution of equilibrium dynamical mean-field equations is feasible.

  16. Temporal dynamics of the primary human T cell response to yellow fever virus 17D as it matures from an effector- to a memory-type response.

    Science.gov (United States)

    Blom, Kim; Braun, Monika; Ivarsson, Martin A; Gonzalez, Veronica D; Falconer, Karolin; Moll, Markus; Ljunggren, Hans-Gustaf; Michaëlsson, Jakob; Sandberg, Johan K

    2013-03-01

    The live attenuated yellow fever virus (YFV) 17D vaccine provides a good model to study immune responses to an acute viral infection in humans. We studied the temporal dynamics, composition, and character of the primary human T cell response to YFV. The acute YFV-specific effector CD8 T cell response was broad and complex; it was composed of dominant responses that persisted into the memory population, as well as of transient subdominant responses that were not detected at the memory stage. Furthermore, HLA-A2- and HLA-B7-restricted YFV epitope-specific effector cells predominantly displayed a CD45RA(-)CCR7(-)PD-1(+)CD27(high) phenotype, which transitioned into a CD45RA(+)CCR7(-)PD-1(-)CD27(low) memory population phenotype. The functional profile of the YFV-specific CD8 T cell response changed in composition as it matured from an effector- to a memory-type response, and it tended to become less polyfunctional during the course of this transition. Interestingly, activation of CD4 T cells, as well as FOXP3(+) T regulatory cells, in response to YFV vaccination preceded the kinetics of the CD8 T cell response. The present results contribute to our understanding of how immunodominance patterns develop, as well as the phenotypic and functional characteristics of the primary human T cell response to a viral infection as it evolves and matures into memory.

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

    CERN Document Server

    Liu, Qingming; 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 for electric resistance evaluation of the full discharge circuit, three poles switch and electric spark induced plasma during the discharge process was put forward. The electric energy consumed by wire, electric switch and electric spark induced plasma between electrodes were obtained by Joules law. The structure of energy distribution and the dynamic process of energy release during the capacitor discharge process have been studied. Experiments results showed that, with the increase of capacitor released energy, the dura...

  18. Intense heat waves: dynamical-physical factors and characteristics of these heat waves

    Directory of Open Access Journals (Sweden)

    Meral Demirtaş

    2017-04-01

    Full Text Available Dynamical and physical factors that trigger and maintain heat waves (HW were examined. Since high pressure systems play a role in HW processes, an atmospheric blocking method was introduced. A HW detection method which employs spatially and temporally changing reference temperature to compute HW parameters was used. Departures from climate averages of 500-hPa geopotential height, 850-hPa temperature, sea-surface-temperatures and soil wetness of 2003, 2012 and 2015 June-July-August were analyzed. HWs were examined together with dynamical and physical factors, atmospheric blocking and HW characteristics. Results indicate that HWs were influential over the Aegean region. Year-to-year variability in summer temperatures is considered as signs of climate variability.

  19. DYNAMIC CHARACTERISTICS OF ELECTRO-HYDRAULIC PROPORTIONAL PRESSURE-FLOW HYBRID VALVE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The structure principles under the flow and pressure working conditions are studied, in order to investigate the dynamic characteristics of the electro-hydraulic proportional pressure-flow hybrid valve. According to the structure principles under the two different working conditions, the transfer functions under such conditions are derived. With the transfer functions, some structure elements that may affect its performance, are investigated, afterwards some principles of optimality and effective methods for improving the dynamic performance of the valve are proposed. The conclusions can be used to instruct engineering applications and products designing. The test results conform to the results of the theoretical analysis and simulation, which proves the correctness of the study and simulation works.

  20. ON NATURAL CHARACTERISTICS OF A RIGID MOTOR FLEXIBLE BASE DYNAMIC COUPLED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Sun Yuguo; Song Kongjie

    2004-01-01

    In shipping and aircraft engineering,the vibrating motor or instrumentation is usually mounted on a non-rigid base.To apply isolation design effectively,it is necessary to investigate the nature vibration characteristics of the rigid motor,flexible base coupled system.A universal dynamic express for the coupled system is derived.A PC-based measurement solution is presented.And the system's dynamic behavior is then investigated numerically and experimentally.The results show that a strong interaction will exist between the motor's rigid mode and the flexible base's mode when the motor's mounting frequency is close to the flexible base's first natural frequency.The first natural frequency of the coupled system is generally lower than the motor's rigid mode frequency.At high frequency,the flexible base's modes are the dominant modes of the coupled system.