Variable Current Transient Beam Loading Compensation
Energy Technology Data Exchange (ETDEWEB)
Farkas, Zoltan D
2000-10-25
The energy spread caused by transients during beam turn-on can be reduced by suitable timing of the beam turn-on[1]. If the beam is injected when the no-load voltage reaches the desired loaded voltage, then the energy spread is about 10%. To eliminate this energy spread, one can amplitude or phase modulate the section input power for one fill time, so that when the beam is turned on, the no-load voltage equals the desired loaded voltage and from then on, the change in no-load voltage tracks the beam induced voltage. It is known that for a constant gradient (CG) structure, and amplitude variation of the form E(t) = a{sub 0} + (1 - a{sub 0}) t{sub p} will reduce the energy spread to zero for a current that is determined by a{sub 0}. When one uses rf modulation for transient beam loading compensation, the beam is injected a fill time after the rf has been turned on, and one is forced to throw away a section's worth of rf energy. In addition, it requires extra components which use up additional rf energy. This note describes transient beam loading compensation with variable current. It will show that it increases the rf energy to beam energy transfer efficiency.
Beam loading compensation in the NLCTA
International Nuclear Information System (INIS)
In the design of the Next Linear Collider (NLC), multi-bunch operation is employed to improve efficiency at the cost of substantial beam loading. The RF pulse that powers the accelerator structures will be shaped to compensate for the effect of the transient loading along the bunch train. This scheme has been implemented in the Next Linear Collider Test Accelerator (NLCTA), a facility built to test the key accelerator technology of the NLC. In this paper the authors describe the compensation method, the techniques used to measure the energy variation along the bunch train, and results from tests with NLC-like beam currents
Beam loading compensation for the NLC low frequency linacs
Energy Technology Data Exchange (ETDEWEB)
Li, Z.; Miller, R.; Farkas, D.; Raubenheimer, T.; Tang, H.; Yeremian, D.
1997-03-01
The NLC low rf linacs are heavily loaded by a beam of about 130 ns in macropulse length (90 bunches) and a current up to 2.75 Amps. Beam loading voltage generates a large energy spread along the bunch train. This energy spread is critical for lattice design and, if not properly compensated, induces emittance growth and in turn lowers the luminosity of the machine. In this paper, the authors study the {Delta}F and {Delta}T beam loading compensation techniques for the NLC low rf linacs. They will apply these methods to the NLC low rf linacs to demonstrate the efficacy of these methods. Finally, they discuss a hybrid {Delta}T + {Delta}F method to improve the efficiency of beam loading compensation.
Beam loading compensation for the NLC low frequency linacs
International Nuclear Information System (INIS)
The NLC low rf linacs are heavily loaded by a beam of about 130 ns in macropulse length (90 bunches) and a current up to 2.75 Amps. Beam loading voltage generates a large energy spread along the bunch train. This energy spread is critical for lattice design and, if not properly compensated, induces emittance growth and in turn lowers the luminosity of the machine. In this paper, the authors study the ΔF and ΔT beam loading compensation techniques for the NLC low rf linacs. They will apply these methods to the NLC low rf linacs to demonstrate the efficacy of these methods. Finally, they discuss a hybrid ΔT + ΔF method to improve the efficiency of beam loading compensation
Compensation of initial beam loading for electron linacs
International Nuclear Information System (INIS)
Serious initial beam loading effect may generate beam loss in the electron linac of the VSX light source. Because of the large energy spread, it is difficult to compensate the beam loading with ordinary methods, such as the adjustment of injection timing and ECS (Energy Compensation System). We have developed a phase-amplitude (Δφ-A) modulation system using two fast phase shifters, which is put before a klystron and operated at low power level. In this paper, we report the performance of the test system. (author)
Beam Loading Compensation in the Main Linac of CLIC
Schulte, D.; Syratchev, I.
2000-01-01
Compensation of multi-bunch beam loading is of great importance in the main linac of the Compact Linear Collider (CLIC). The bunch-to-bunch energy variation has to stay below 1 part in 1000. In CLIC, the RF power is obtained by decelerating a drive beam which is formed by merging a number of short bunch trains. A promising scheme for tackling beam loading in the main linac is based on varying the lengths of the bunch trains in the drive beam. The scheme and its expected performance are presen...
Beam loading compensation with variable group velocity
Energy Technology Data Exchange (ETDEWEB)
Farkas, Z.D.
1992-08-01
Consider a section with linearly variable group velocity and a beam pulse shorter than the section fill time. Choose the current amplitude so that the gradient of the last bunch equals the gradient of the first bunch. For beam pulses less than about 15% of fill time, the voltage deviation during the beam pulse is small, but as the pulse width increases the voltage deviation also increases. We show that by decreasing the output to input group velocity ratio, we can reduce the first order voltage deviation, and that we can remove the remaining second-order voltage deviation by linearly decreasing the section input power by a small amount starting at beam injection time. This way we can increase the beam pulse width to more than half the fill time, and thereby increase the RF to beam energy transfer efficiency and the luminosity without increasing the voltage deviation.
First beam test of ΔΦ-A initial beam loading compensation for electron linacs
International Nuclear Information System (INIS)
The initial-beam-loading effect may cause serious beam loss in the electron linac of the Super SOR light source. Because of the large energy spread, it is difficult to compensate the beam loading with ordinary methods, such as the adjustment of injection timing and ECS (Energy Compensation System). A phase-amplitude (ΔΦ-A) modulation system has already been developed and tested. First beam test using this system was carried out at the 125 MeV electron linac of Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. Its result shows that our system well corrects the energy spread due to initial beam loading effect. In this paper, we report the results of first beam test. (author)
Multi-harmonic beam loading compensation in the J-PARC RCS
International Nuclear Information System (INIS)
For acceleration of high intensity proton beams in the J-PARC RCS, the beam loading compensation is important. In the wide-band (Q = 2) MA-loaded RF cavity, the wake voltage consists of not only the fundamental accelerating harmonic component (h = 2) but also the higher harmonics. The higher harmonic components cause the RF bucket distortion. We employ the RF feedforward method to compensate the multi-harmonic beam loading. The full-digital feedforward system is developed, which compensates the most important three harmonic components (h = 2, 4, 6) of the wake voltages. We present the results of the beam commissioning with a high intensity proton beam (2.5x1013 ppp). The impedance seen by the beam is greatly reduced. We also report the beneficial effects of the feedforward compensation in the beam operation. (author)
Beam loading and cavity compensation for the Ground Test Accelerator
International Nuclear Information System (INIS)
The Ground Test Accelerator (GTA) will be heavily beam-loaded H- linac with tight tolerances on accelerating field parameters. The methods used in modeling the effects of beam loading in this machine are described. The response of the cavity to both beam and radio-frequency (RF) drive stimulus is derived, including the effects of cavity detuning. This derivation is not restricted to a small-signal approximation. An analytical method for synthesizing a predistortion network that decouples the amplitude and phase responses of the cavity is also outline. Simulation of performance, including beam loading, is achieved through use of a control system analysis software package. A straightforward method is presented for extrapolating this work to model large coupled structures with closely spaced parasitic modes. Results to date have enabled the RF control system designs for GTA to be optimized and have given insight into their operation. 6 refs., 10 figs
Beam loading compensation for acceleration of multi-bunch electron beam train
International Nuclear Information System (INIS)
The laser undulator compact X-ray source (LUCX) is a test bench used with the compact, high-brightness X-ray generator at KEK (High Energy Accelerator Research Organization). Our group is conducting experiments with LUCX to demonstrate the possibility of K-edge digital subtraction angiography, based on Compton scattering. One of the challenging problems is to generate high-brightness multi-bunch electron beams to compensate for the energy difference arising from the beam loading effect. In this paper we calculate the transient beam loading voltage and energy gain from the RF field in the gun and accelerating tube for a multi-bunch train. To do so we consider the process by which the RF field builds up in the gun and accelerating tube, and the special shape of the RF pulse. We generate and accelerate 100 bunches with a 50 nC electron bunch train, effectively compensating for the beam loading effect by adjusting the injection timing. Using a beam position monitor (BPM) and optical transition radiation (OTR) system, we measure the electron beam energy bunch by bunch. The average energy of a 100-bunch train is 40.5 MeV and the maximum energy difference from bunch to bunch is 0.26 MeV
CLIC Main Linac Beam-Loading Compensation by Drive Beam Phase Modulation
Corsini, R; Syratchev, I V
1999-01-01
The CLIC final focus momentum acceptance of ± 0.5 % limits the bunch-to-bunch energy variation in the main beam to less than ± 0.1 %, since the estimated single-bunch contribution is ± 0.4 %. On the other hand, a relatively high beam-loading of the main accelerating structures (about 16 %) is unavoidable in order to optimize the RF-to-beam efficiency. Therefore, a compensation method is needed to reduce the resulting bunch-to-bunch energy spread of the main beam. Up to now, it has been planned to obtain the RF pulse shape needed for compensation by means of a charge ramp in the drive beam pulse. On the other hand, the use of constant-current drive beam pulses would make the design and operation of the drive beam injector considerably simpler. In this paper we present a possible solution adapted to the CLIC two-beam scheme with constant-current pulses, based on phase modulation of the drive beam bunches.
Transient beam loading compensation in traveling wave linear accelerators
International Nuclear Information System (INIS)
For normal conducting linear colliders the transient beam loading in the accelerating structures is typically of the order of 20-30%. This results in a multibunch energy spread of the same magnitude if no remedy is taken into account. On the other hand, in a linear collider the transient energy spread has to be controlled down to a few tenth of a percent. Two possible methods, assuming two different setups, e.g. klystron plus structure and klystron plus SLED cavity plus structure, are investigated. A description of the whole rf system and the resulting energy spread is presented especially for the case of the S-Band linear collider study. (orig.)
A scheme to compensate the transient beam loading in TW electron linacs
International Nuclear Information System (INIS)
A scheme to compensate the transient beam loading of the TW electron linac operated in multi-bunch mode is described. The proposed method is to excite an auxiliary cavity located at the end of the accelerator section with the residual rf power, which comes out of the section after one filling time, with properly adjusted phase and amplitude of the field. The transient energy gain of the electron beam in passing through the cavity will compensate the transient energy loss due to beam loading in the accelerator section. The parameters of ATF of Brookhaven National Laboratory are used for calculation as an example to illustrate the result of computation
Initial-beam-loading compensation system for high-intensity electron linacs
International Nuclear Information System (INIS)
We developed an initial-beam-loading compensation system for electron linacs. This system consists of a ΔΦ-A (phase-to-amplitude) modulator and a fast-phase detector. The ΔΦ-A modulator can modulate the phase and the amplitude of a low-power RF simultaneously. Low-power and high-power tests were successfully carried out at KEK. The result of the high-power tests show that our system can reduce the energy spread from 27 to 0.3% for a 300-mA average current. The system that we developed can be a powerful tool for initial-beam-loading compensation. In addition, a numerical calculation method using the power-flow matrix was formulated to perform a fast beam-energy calculation with a simple algorithm. This method can be used to obtain the target RF waveform for energy-spread compensation
Transient beam-loading model and compensation in Compact Linear Collider main linac
Kononenko, O
2011-01-01
A new model to compensate for the transient beam loading in the CLIC main linac is developed. It takes into account the CLIC specific power generation scheme and the exact 3D geometry of the accelerating structure including couplers. A new method of calculating unloaded and loaded voltages during the transient is proposed and a dedicated optimization scheme of the rf pulse to compensate the transient beam-loading effect is presented. It is demonstrated that the 0.03% limit on the rms relative bunch-to-bunch energy spread in the main beam after acceleration can be reached. The optimization technique has been used to increase the rf to beam efficiency while preserving the CLIC requirements and to compensate for the energy spread caused by the Balakin-Novokhatski-Smirnov damping and transient process in the subharmonic buncher. Effects of charge jitters in the drive and main beams are studied. It is shown that within the 0.1% CLIC specification limit on the rms spread in beams charge the energy spread is not sig...
Gamp, Alexander
2013-01-01
We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.
Study on transient beam loading compensation for China ADS proton linac injector II
Gao, Zheng; Wang, Xian-Wu; Chang, Wei; Zhang, Rui-Feng; Zhu, Zheng-Long; Zhang, Sheng-Hu; Chen, Qi; Powers, Tom
2016-01-01
Significant transient beam loading effects were observed during beam commissioning tests of prototype II of the injector for the Accelerator Driven Sub-critical (ADS) system, which took place at the Institute of Modern Physics, Chinese Academy of Sciences, between October and December 2014. During these tests experiments were performed with CW operation of the cavities with pulsed beam current, and the system was configured to make use of a prototype digital low level radio frequency (LLRF) controller. The system was originally operated in pulsed mode with a simple PID feedback control algorithm, which was not able to maintain the desired gradient regulation during pulsed 10 mA beam operations. A unique simple transient beam loading compensation method which made use of a combination of PI feedback and feedforward control algorithm was implemented in order to significantly reduce the beam induced transient effect in the cavity gradients. The superconducting cavity field variation was reduced to less than 1.7%...
Pulse-by-pulse switching of beam loading compensation in J-PARC Linac LLRF
International Nuclear Information System (INIS)
For the J-PARC linac low level RF system, in order to compensate beam-loading change by pulses in the operation of 25-Hz repetition, a function that switches the feed-forward control parameters in every pulse were installed into the digital accelerating-field control system. The linac provides a 50-mA peak current proton beam to a 3-GeV rapid-cycling synchrotron (RCS). Then the RCS distributes the 3-GeV beam into a following 50-GeV synchrotron (main ring, MR) and the Materials and Life Science Facility (MLF), which is one of the experimental facilities in the J-PARC. The 500-us long macro pulses from the ion source of the linac should be chopped into medium pulses for injection into the RCS. The duty (width or repetition) of the medium pulse depends on which facility the RCS provides the beam to the MR or MLF. Therefore the beam loading compensation needs to be corrected for the change of the medium pulse duty in the 25-Hz operation. (author)
Study on transient beam loading compensation for China ADS proton linac injector II
Gao, Zheng; He, Yuan; Wang, Xian-Wu; Chang, Wei; Zhang, Rui-Feng; Zhu, Zheng-Long; Zhang, Sheng-Hu; Chen, Qi; Powers, Tom
2016-05-01
Significant transient beam loading effects were observed during beam commissioning tests of prototype II of the injector for the accelerator driven sub-critical (ADS) system, which took place at the Institute of Modern Physics, Chinese Academy of Sciences, between October and December 2014. During these tests experiments were performed with continuous wave (CW) operation of the cavities with pulsed beam current, and the system was configured to make use of a prototype digital low level radio frequency (LLRF) controller. The system was originally operated in pulsed mode with a simple proportional plus integral and deviation (PID) feedback control algorithm, which was not able to maintain the desired gradient regulation during pulsed 10 mA beam operations. A unique simple transient beam loading compensation method which made use of a combination of proportional and integral (PI) feedback and feedforward control algorithm was implemented in order to significantly reduce the beam induced transient effect in the cavity gradients. The superconducting cavity field variation was reduced to less than 1.7% after turning on this control algorithm. The design and experimental results of this system are presented in this paper. Supported by National Natural Science Foundation of China (91426303, 11525523)
Numerical investigation of transient beam loading compensation in JLC X-band main linac
International Nuclear Information System (INIS)
In the present paper, two methods, 'staggered timing' and 'RF modulation', were studied for the transient beam loading compensation in the JLC X-band main linac. The inter bunch energy spread was found to be easily reduced down to less than ±0.06% with 10 sets of injection timings along the linac in the former case while with a simple linear ramping of the input RF voltage in the latter case. For both cases the energy transfer efficiencies from the power source to the beam were exactly the same. The tolerance of the beam intensity jitter was found to be ±1% for the multibunch energy spread of ±0.1%. (author)
Beam loading compensation in thermionic RF gun by using RF detuning
International Nuclear Information System (INIS)
A new beam energy compensation method was investigated, which can suppress the beam energy drop in a thermionic RF gun caused by the beam current increase due to the back-bombardment effect. The method is to feed a RF power with slightly higher (detuned) frequency to the gun. The principle of this method is based on that the increment of the beam conductance could be cancelled out by the increment of beam suceptance. As a result of numerical simulation, the increase of current density on the cathode surface from 47 to 176 A/cm2 can be compensated by 550 kHz detuned RF power. Results of experiment showed a good agreement with the simulation, and the effectiveness of this method was demonstrated. (author)
International Nuclear Information System (INIS)
In this paper, a new method of transient beam loading compensation for the next generation of TeV e+e- linear collider with multibunching is presented. The method is based on applications of the π/2 - mode standing wave accelerating structure with the reflected wave used for beam loading compensation. Various compensation methods for transient beam loading for the constant gradient traveling wave and π/2 standing wave structures are compared. It is shown that the proposed method provides an approximately 10% higher efficiency of the RF source energy utilization than that for the traveling wave accelerating structure. (author)
Beam loading compensation of traveling wave linacs through the time dependence of the rf drive
International Nuclear Information System (INIS)
Beam loading in traveling-wave linear accelerating structures leads to unacceptable spread of particle energies across an extended train of bunched particles due to beam-induced field and dispersion. Methods for modulating the rf power driving linacs are effective at reducing energy spread, but for general linacs do not have a clear analytic foundation. We report here methods for calculating how to modulate the rf drive in arbitrarily nonuniform traveling-wave linacs within the convective-transport (power-diffusion) model that results in no additional energy spread due to beam loading (but not dispersion). Varying group velocity, loss factor, and cell quality factor within a structure, and nonzero particle velocity, are handled.
Tamura, Fumihiko; Ohmori, Chihiro; Yamamoto, Masanobu; Yoshii, Masahito; Schnase, Alexander; Nomura, Masahiro; Toda, Makoto; Shimada, Taihei; Hasegawa, Katsushi; Hara, Keigo
2013-05-01
Beam loading compensation is a key for acceleration of a high intensity proton beam in the main ring (MR) of the Japan Proton Accelerator Research Complex (J-PARC). Magnetic alloy loaded rf cavities with a Q value of 22 are used to achieve high accelerating voltages without a tuning bias loop. The cavity is driven by a single harmonic (h=9) rf signal while the cavity frequency response also covers the neighbor harmonics (h=8,10). Therefore the wake voltage induced by the high intensity beam consists of the three harmonics, h=8,9,10. The beam loading of neighbor harmonics is the source of periodic transient effects and a possible source of coupled bunch instabilities. In the article, we analyze the wake voltage induced by the high intensity beam. We employ the rf feedforward method to compensate the beam loading of these three harmonics (h=8,9,10). The full-digital multiharmonic feedforward system was developed for the MR. We describe the system architecture and the commissioning methodology of the feedforward patterns. The commissioning of the feedforward system has been performed by using high intensity beams with 1.0×1014 proteins per pulse. The impedance seen by the beam is successfully reduced and the longitudinal oscillations due to the beam loading are reduced. By the beam loading compensation, stable high power beam operation is achieved. We also report the reduction of the momentum loss during the debunching process for the slow extraction by the feedforward.
Kelisani, M. Dayyani; Doebert, S.; Aslaninejad, M.
2016-08-01
The critical process of beam loading compensation in high intensity accelerators brings under control the undesired effect of the beam induced fields to the accelerating structures. A new analytical approach for optimizing standing wave accelerating structures is found which is hugely fast and agrees very well with simulations. A perturbative analysis of cavity and waveguide excitation based on the Bethe theorem and normal mode expansion is developed to compensate the beam loading effect and excite the maximum field gradient in the cavity. The method provides the optimum values for the coupling factor and the cavity detuning. While the approach is very accurate and agrees well with simulation software, it massively shortens the calculation time compared with the simulation software.
Beam - cavity interaction beam loading
International Nuclear Information System (INIS)
The interaction of a beam with a cavity and a generator in cyclic accelerators or storage rings is investigated. Application of Maxwell's equations together with the nonuniform boundary condition allows one to get an equivalent circuit for a beam-loaded cavity. The general equation for beam loading is obtained on the basis of the equivalent circuit, and the beam admittance is calculated. Formulas for power consumption by a beam-loaded cavity are derived, and the optimal tuning and coupling factor are analyzed. (author)
Development of multi-bunch beam energy compensation method
International Nuclear Information System (INIS)
A method to compensate for beam loading effects in a multi-bunch beam is under development at Accelerator Test Facility (ATF) in KEK. In this paper we describe the rf high power test for ΔT energy compensation by using the SLED cavities. In this ΔT (early injection and amplitude modulation) energy compensation method, the input waveform into accelerating structure is changed by controlling the rf phase and combining the rf-power from two klystrons with a 3 dB hybrid combiner to compensate multi-bunch beam energy for various beam currents. In this test, an arbitrary waveform was generated by changing the rotating speed of the each klystron phase into the opposite direction and the beam test will be done soon. (author)
Digitally compensated beam current transformer
Kesselman, Martin
2005-01-01
The Spallation Neutron Source (SNS) is being built by a collaboration of six laboratories. Beam current monitors (BCMs) will be used to record the current of H-minus and H-plus beams ranging from 15 mA (tune-up in the Front End and Linac) to over 60A fully accumulated in the Ring and dumped to the load as a single pulse in the Ring to Beam Target (RTBT). The time structure of these beams ranges from 645ns "mini" bunches at the 1.05 MHz ring revolution rate, to an overall 1 ms long macro-pulse. The requirements for the BCMs will depend upon their location within the system. The need to measure individual mini-pulses, examine the characteristics of the chopper edge, as well as the longer average current pulse of the macropulse, or long duration pulses during Linac tuning place wide requirements upon the response of current transformers. To obtain the desired accuracy and resolution, current transformers must have less than 1 ns rise time and droops of 0.1 %/ms. This places a significant design burden on the cur...
Compensator configurations for load currents' symmetrization
Rusinaru, D.; Manescu, L. G.; Dinu, R. C.
2016-02-01
This paper approaches aspects regarding the mitigation effects of asymmetries in 3-phase 3-wire networks. The measure consisting in connecting of load current symmetrization devices at the load coupling point is presented. A time-variation of compensators parameters is determined as a function of the time-recorded electrical values. The general sizing principle of the load current symmetrization reactive components is based on a simple equivalent model of the unbalanced 3-phase loads. By using these compensators a certain control of the power components transits is ensured in the network. The control is based on the variations laws of the compensators parameters as functions of the recorded electrical values: [B] = [T]·[M]. The link between compensator parameters and measured values is ensured by a transformation matrix [T] for each operation conditions of the supply network. Additional conditions for improving of energy and efficiency performance of the compensator are considered: i.e. reactive power compensation. The compensator sizing algorithm was implemented into a MATLAB environment software, which generate the time-evolution of the parameters of load current symmetrization device. The input data of application takes into account time-recording of the electrical values. By using the compensator sizing software, some results were achieved for the case of a consumer connected at 20 kV busbar of a distribution substation, during 24 hours measurement session. Even the sizing of the compensators aimed some additional network operation aspects (power factor correction) correlated with the total or major load symmetrizations, the harmonics aspects of the network values were neglected.
LHC beam-beam compensation using wires and electron lenses
Dorda, U; Shiltsev, V; Zimmermann, F
2007-01-01
We present weak-strong simulation results for a possible application of current-carrying wires and electron lenses to compensate the LHC long-range and head-on beambeam interaction, respectively, for nominal and PACMAN bunches. We show that these measures have the potential to considerably increase the beam-beam limit, allowing for a corresponding increase in peak luminosity.
Beam transport and space charge compensation strategies (invited)
Energy Technology Data Exchange (ETDEWEB)
Meusel, O., E-mail: o.meusel@iap.uni-frankfurt.de; Droba, M.; Noll, D.; Schulte, K.; Schneider, P. P.; Wiesner, C. [IAP, Goethe University Frankfurt, Frankfurt D-60438 (Germany)
2016-02-15
The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree of space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed.
A NEW HYSTERESIS COMPENSATION METHOD FOR LOAD CELLS
Institute of Scientific and Technical Information of China (English)
ZhuZijian; ChenRenwen
2002-01-01
A new hysteresis compensation method is presented.After analyzing the characteristics of strain-gage based load cells under loading & unloading conditions, mathe-matical models are established.A solution to compensate the hysteresis of the load cell by the experiments.It is shown that the method is reliable and can effectively re-duce the hysteresis.
Study on space charge compensation in negative hydrogen ion beam.
Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E
2016-02-01
Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.
Study on space charge compensation in negative hydrogen ion beam.
Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E
2016-02-01
Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results. PMID:26932087
Study on space charge compensation in negative hydrogen ion beam
Energy Technology Data Exchange (ETDEWEB)
Zhang, A. L.; Chen, J. E. [University of Chinese Academy of Sciences, Beijing 100049 (China); State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Peng, S. X., E-mail: sxpeng@pku.edu.cn; Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y. [State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China)
2016-02-15
Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H{sup +} beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H{sup −} beam from a 2.45 GHz microwave driven H{sup −} ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.
Generation of compensated ion beams from source with oscillating electrons
Borisko, V N; Yunakov, N N
2000-01-01
The generation of compensated ion beams from electrically unsymmetrical reflecting discharge was investigated.The spatial location of a compensation zone,the optimal values of operating gas pressures P=(0.8/1) centre dot 10 sup - sup 4 Torr and potential difference between cathodes DELTA U = 80B were determined.The way to control the current compensation degree of the extracted ion beam a several to 100% was found.
Compensating tune spread induced by space charge in bunched beams
Energy Technology Data Exchange (ETDEWEB)
Litvinenko, V.; Wang, G.
2015-05-03
The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Using an appropriate electron beam would compensate both the tune shift and the tune spread in the hadron beam in a coasting beam. But these methods cannot compensate space charge tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with mismatched longitudinal velocity to compensate the space charge induced tune-shift and tune spread.
MOTION COMPENSATION FOR WIDE BEAM SAR BASED ON FREQUENCY DIVISION
Institute of Scientific and Technical Information of China (English)
Zheng Xiaoshuang; Yu Weidong; Li Zaoshe
2008-01-01
Aperture-dependent motion compensation is important for wide beam Synthetic Aperture Radar (SAR) data processing. This paper studies a wide beam motion compensation algorithm based on frequency division. It takes blocks along azimuth dimension in frequency domain and applies an-gle-variant motion compensation in time domain. With this frequency division based motion com-pensation approach,the effects of aperture-dependent residual phase errors are corrected precisely. The rationale and procedure of this algorithm are introduced in detail. Point targets and images of a P-band airborne SAR with motion errors are simulated to validate this algorithm. Compared with the wide beam motion compensation algorithms based on time division,the proposed algorithm has better performance,especially in terms of high-frequency motion errors.
Beam test of multi-bunch energy compensation system in the accelerator test facility at KEK
International Nuclear Information System (INIS)
A beam test of the multi-bunch energy compensation system (ECS) was performed using the ΔF method with the 2856±4.327 HMz accelerating structures in the accelerator test facility (ATF) at KEK. The 1.54 GeV S-band linac of the ATF was designed to accelerate a multi-bunch beam the consists of 20 bunches with 2.8 ns spacing. The multi-bunch beam with 2.0 x 1010 electrons/bunch has an energy deviation of about 8.5% at the end of the linac due to transient beam loading without ECS. The ATF linac is the injector of the ATF damping ring (DR), whose energy acceptance is ±0.5%. The beam loading compensation system is necessary in the ATF linac for the successful injection of multi-bunch into DR. The rf system of the linac consists of 8 regular rf units with the SLED system and 2 ECS rf units without the SLED system. The accelerating structures of the regular units are driven at 2856 MHz and the 2 ECS structures are operated with slightly different rf frequencies of 2856±4.327 MHz. In the beam test, we have succeeded in compressing the multi-bunch energy spread within the energy acceptance of the DR using ΔF ECS. The principle of the beam loading compensation system of KEK-ATF and the experimental results are described in this paper. (author)
Energy compensation of slow extracted beams with RF acceleration
Fujimoto, Tetsuya; Souda, Hikaru; Torikoshi, Masami; Kanai, Tatsuaki; Yamada, Satoru; Noda, Koji
2016-03-01
In a conventional carbon-ion radiotherapy facility, a carbon-ion beam is typically accelerated up to an optimum energy, slowly extracted from a synchrotron ring by a resonant slow extraction method, and ultimately delivered to a patient through a beam-delivery system. At Japan's Gunma University, a method employing slow-beam extraction along with beam-acceleration has been adopted. This method slightly alters the extracted-beam's energy owing to the acceleration component of the process, which subsequently results in a residual-range variation of approximately 2 mm in water-equivalent length. However, this range variation does not disturb a distal dose distribution with broad-beam methods such as the single beam-wobbling method. With the pencil-beam 3D scanning method, however, such a range variation disturbs a distal dose distribution because the variation is comparable to slice thickness. Therefore, for pencil-beam 3D scanning, an energy compensation method for a slow extracted beam is proposed in this paper. This method can compensate for the aforementioned energy variances by controlling net energy losses through a rotatable energy absorber set fixed between the synchrotron exit channel and the isocenter. Experimental results demonstrate that beam energies can be maintained constant, as originally hypothesized. Moreover, energy-absorber positions were found to be significantly enhanced by optimizing beam optics for reducing beam-size growth by implementation of the multiple-scattering effect option.
Vibration compensating beam scanning interferometer for surface measurement
Jiang, Xiang; Martin, Haydn; Wang, Kaiwei
2007-01-01
Light beam scanning using a dispersive element and wavelength tuning is coupled with fibre-optic interferometry to realize a new surface measurement instrument. The instrument is capable of measuring nano-scale surface structures and form deviation. It features active vibration compensation and a small optical probe size that may be placed remotely from the main apparatus. Active vibration compensation is provided by the multiplexing of two interferometers with near common paths. Closed loop ...
Voltage Unbalance Compensation with Smart Three-phase Loads
DEFF Research Database (Denmark)
Douglass, Philip; Trintis, Ionut; Munk-Nielsen, Stig
2016-01-01
This paper describes the design, proof-of-concept simulations and laboratory test of an algorithm for controlling active front-end rectifiers to reduce voltage unbalance. Using inputs of RMS voltage, the rectifier controller allocates load unevenly on its 3 phases to compensate for voltage...
Compensation techniques in NIRS proton beam radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Akanuma, A. (Univ. of Tokyo, Japan); Majima, H.; Furukawa, S.
1982-09-01
Proton beam has the dose distribution advantage in radiation therapy, although it has little advantage in biological effects. One of the best advantages is its sharp fall off of dose after the peak. With proton beam, therefore, the dose can be given just to cover a target volume and potentially no dose is delivered thereafter in the beam direction. To utilize this advantage, bolus techniques in conjunction with CT scanning are employed in NIRS proton beam radiation therapy planning. A patient receives CT scanning first so that the target volume can be clearly marked and the radiation direction and fixation method can be determined. At the same time bolus dimensions are calculated. The bolus frames are made with dental paraffin sheets according to the dimensions. The paraffin frame is replaced with dental resin. Alginate (a dental impression material with favorable physical density and skin surface contact) is now employed for the bolus material. With fixation device and bolus on, which are constructed individually, the patient receives CT scanning again prior to a proton beam treatment in order to prove the devices are suitable. Alginate has to be poured into the frame right before each treatments. Further investigations are required to find better bolus materials and easier construction methods.
Baudrenghien, P
2005-01-01
The high intensity regime is reached when the voltage induced by the beam in the RF cavities is of an amplitude comparable to the desired accelerating voltage. In steady state this beam loading can be compensated by providing extra RF power. Transient beam loading occurs at injection or in the presence of a beam intensity that is not uniform around the ring. The transients are periodic at the revolution frequency. Without correction transient beam loading can be very harmful: The stable phase and bucket area will not be equal for all bunches. Strong beam loading often goes in pair with longitudinal instabilities because the RF cavities are a large contributor to the total ring impedance. The low level systems that reduce the effect of the transient beam loading will also increase the threshold intensity of the longitudinal instability caused by the cavity impedance at the fundamental RF frequency. Four classic methods are presented here: Feedforward, RF feedback, long delay feedback and bunch by bunch feedbac...
A Novel Control algorithm based DSTATCOM for Load Compensation
R, Sreejith; Pindoriya, Naran M.; Srinivasan, Babji
2015-11-01
Distribution Static Compensator (DSTATCOM) has been used as a custom power device for voltage regulation and load compensation in the distribution system. Controlling the switching angle has been the biggest challenge in DSTATCOM. Till date, Proportional Integral (PI) controller is widely used in practice for load compensation due to its simplicity and ability. However, PI Controller fails to perform satisfactorily under parameters variations, nonlinearities, etc. making it very challenging to arrive at best/optimal tuning values for different operating conditions. Fuzzy logic and neural network based controllers require extensive training and perform better under limited perturbations. Model predictive control (MPC) is a powerful control strategy, used in the petrochemical industry and its application has been spread to different fields. MPC can handle various constraints, incorporate system nonlinearities and utilizes the multivariate/univariate model information to provide an optimal control strategy. Though it finds its application extensively in chemical engineering, its utility in power systems is limited due to the high computational effort which is incompatible with the high sampling frequency in these systems. In this paper, we propose a DSTATCOM based on Finite Control Set Model Predictive Control (FCS-MPC) with Instantaneous Symmetrical Component Theory (ISCT) based reference current extraction is proposed for load compensation and Unity Power Factor (UPF) action in current control mode. The proposed controller performance is evaluated for a 3 phase, 3 wire, 415 V, 50 Hz distribution system in MATLAB Simulink which demonstrates its applicability in real life situations.
Contributions to the mini-workshop on beam-beam compensation in the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Shiltsev, V.
1998-02-01
The purpose of the Workshop was to assay the current understanding of compensation of the beam-beam effects in the Tevatron with use of low-energy high-current electron beam, relevant accelerator technology, along with other novel techniques of the compensation and previous attempts. About 30 scientists representing seven institutions from four countries--FNAL, SLAC, BNL, Novosibirsk, CERN, and Dubna were in attendance. Twenty one talks were presented. The event gave firm ground for wider collaboration on experimental test of the compensation at the Tevatron collider. This report consists of vugraphs of talks given at the meeting.
Oscillations of end loaded cantilever beams
Macho-Stadler, E.; Elejalde-García, M. J.; Llanos-Vázquez, R.
2015-09-01
This article presents several simple experiments based on changing transverse vibration frequencies in a cantilever beam, when acted on by an external attached mass load at the free end. By using a mechanical wave driver, available in introductory undergraduate laboratories, we provide various experimental results for end loaded cantilever beams that fit reasonably well into a linear equation. The behaviour of the cantilever beam’s weak-damping resonance response is studied for the case of metal resonance strips. As the mass load increases, a more pronounced decrease occurs in the fundamental frequency of beam vibration. It is important to note that cantilever construction is often used in architectural design and engineering construction projects but current analysis also predicts the influence of mass load on the sound generated by musical free reeds with boundary conditions similar to a cantilever beam.
Energy Technology Data Exchange (ETDEWEB)
Stancari, Giulio
2014-09-11
Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.
Electron Beam Energy Compensation by Controlling RF Pulse Shape
Kii, T; Kusukame, K; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H
2005-01-01
We have studied on improvement of electron beam macropulse properties from a thermionic RF gun. Though a thermionic RF gun has many salient features, there is a serious problem that back-bombardment effect worsens quality of the beam. To reduce beam energy degradation by this effect, we tried to feed non-flat RF power into the gun. As a result, we successfully obtained about 1.5 times longer macropulse and two times larger total charge per macropulse. On the other hand, we calculated transient evolution of RF power considering non-constant beam loading. The beam loading is evaluated from time evolution of cathode temperature, by use of one dimensional heat conduction model and electron trajectories' calculations by a particle simulation code. Then we found good agreement between the experimental and calculation results. Furthermore, with the same way, we studied the electron beam output dependence on the cathode radius.
International Nuclear Information System (INIS)
At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it has to be considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the bunch by bunch energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1% p-p, while 5% p-p without compensation. In this conference, we will report our multi-bunch electron beam linac system, the details of energy compensation method using the RF amplitude modulation and the results of beam experiment. (author)
Voltage Unbalance Compensation with Smart Three-phase Loads
DEFF Research Database (Denmark)
Douglass, Philip; Trintis, Ionut; Munk-Nielsen, Stig
2016-01-01
This paper describes the design, proof-of-concept simulations and laboratory test of an algorithm for controlling active front-end rectifiers to reduce voltage unbalance. Using inputs of RMS voltage, the rectifier controller allocates load unevenly on its 3 phases to compensate for voltage unbala...... is caused by asymmetrical loads. These results suggest that the optimal algorithm to reduce system unbalance depends on which system parameter is most important: phase-neutral voltage unbalance, phase-phase voltage unbalance, or current unbalance....
Experimental Studies of Compensation of Beam-Beam Effects with Tevatron Electron Lenses
Energy Technology Data Exchange (ETDEWEB)
Shiltsev, V.; /Fermilab; Alexahin, Yu.; Bishofberger, Kip; Kamerdzhiev, V.; Parkhomchuk, V.; Reva, V.; Solyak, N.; Wildman, D.; Zhang, X.-L.; Zimmermann, F.; /Fermilab /Los Alamos /Novosibirsk, IYF /CERN
2008-02-01
Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this article we present the results of various beam experiments with 'electron lenses', novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses.
Testing Long-Range Beam-Beam Compensation for the LHC Luminosity Upgrade
Rijoff, T L
2012-01-01
The performance of the Large Hadron Collider (LHC) at CERN and its minimum crossing angle are limited by the effect of long-range beam-beam collisions. A wire compensators can mitigate part of the long-range effects and may allow for smaller crossing angles, or higher beam intensity. A prototype long-range wire compensator could be installed in the LHC by 2014/15. Since the originally reserved position for such a wire compensator is not available for this first step, we explore other possible options. Our investigations consider various longitudinal and transverse locations, different wire shapes, different optics configurations and several crossing angles between the two colliding beams. Simulations are carried out with the weak-strong code BBtrack. New postprocessing tools are introduced to analyse tune footprints and particle stability. In particular, a new method for the Lyapunov coefficient calculation is implemented. Submitted as "Tesi di laurea" at the University of Milano, 2012.
Motion compensation with a scanned ion beam: a technical feasibility study
Kraft Gerhard; Haberer Thomas; Bert Christoph; Grözinger Sven; Rietzel Eike
2008-01-01
Abstract Background Intrafractional motion results in local over- and under-dosage in particle therapy with a scanned beam. Scanned beam delivery offers the possibility to compensate target motion by tracking with the treatment beam. Methods Lateral motion components were compensated directly with the beam scanning system by adapting nominal beam positions according to the target motion. Longitudinal motion compensation to mitigate motion induced range changes was performed with a dedicated w...
Stancari, Giulio
2014-01-01
Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compens...
Some Features of Transverse Instability of Partly Compensated Proton Beams
Energy Technology Data Exchange (ETDEWEB)
Vadim Dudnikov
2001-10-23
suppression of generation and accumulation of secondary particles is a traditional method for suppression the transverse electron-proton instability: improve the vacuum, use a gap in beam for electron removing, use cleaning electrodes, suppressing secondary emission. But opposite solution is also possible. Transverse e-p instability in proton rings can be damped by increasing beam density and the rate of secondary particles generation above a threshold level, with decrease of the unstable wavelength below a transverse beam size. In high current Proton Storage Rings (PSR) such as, the LANSCE PSR it is possible to reach this island of stability by multiturn, concentrated charge exchange injection without painting and by enhanced generation of secondary plasma. This possibility was demonstrated in smaller scale PSR at the INP, Novosibirisk [1]. Damping of the e-p instability allowed to accumulate a coasting, space charge compensated, circulating proton beam with intensity, corresponding to the Laslett tune shift of {Delta}{nu} = 5 in the ring with original tune of {nu} = 0.85. In the other PSR transverse instability of bunched beam was damped by a simple feed back [2,3]. In this article they discuss experimental observations of transverse instability of proton beams in different accelerators and storage rings and consider methods to damp the instability. The presented experimental dates could be useful for verification of computer simulation tools developed for investigation of space charge effects and beam instabilities in realistic conditions [4,5].
Method for compensating bellows pressure loads while accommodating thermal deformations
International Nuclear Information System (INIS)
Many metal bellows are used on storage ring vacuum chambers. They allow the ring to accommodate deformations associated with alignment, mechanical assembly and thermal expansion. The NSLS has two such electron storage rings, the VUV ring and the X-Ray ring. Both rings utilize a number of welded metal bellows within the ring and at every beam port. There are provisions for 16 beam ports on the VUV and 28 ports of the X-Ray ring. At each of these locations the bellows are acted on by an external pressure of 1 atmosphere, which causes a 520 lb. reaction at the vacuum chamber beam port and at the beamline flange downstream of the bellows. The use of rigid tie rods across the bellows flanges to support the load is troublesome because most storage ring vacuum chambers are baked in situ to achieve high internal vacuum. Significant forces can develop on components if thermal deformation is restrained and damage could occur
Method for compensating bellows pressure loads while accommodating thermal deformations
Energy Technology Data Exchange (ETDEWEB)
Woodle, M.H.
1985-01-01
Many metal bellows are used on storage ring vacuum chambers. They allow the ring to accommodate deformations associated with alignment, mechanical assembly and thermal expansion. The NSLS has two such electron storage rings, the vuv ring and the x-ray ring. Both rings utilize a number of welded metal bellows within the ring and at every beam port. There are provisions for 16 beam ports on the vuv and 28 ports in the x-ray ring. At each of these locations the bellows are acted on by an external pressure of 1 atmosphere, which causes a 520 lb reaction at the vacuum chamber beam port and at the beamline flange downstream of the bellows. The use of rigid tie rods across the bellows flanges to support this load is troublesome because most storage ring vacuum chambers are baked in situ to achieve high internal vacuum. Significant forces can develop on components if thermal deformation is restrained and damage could occur.
Motion compensation with a scanned ion beam: a technical feasibility study
International Nuclear Information System (INIS)
Intrafractional motion results in local over- and under-dosage in particle therapy with a scanned beam. Scanned beam delivery offers the possibility to compensate target motion by tracking with the treatment beam. Lateral motion components were compensated directly with the beam scanning system by adapting nominal beam positions according to the target motion. Longitudinal motion compensation to mitigate motion induced range changes was performed with a dedicated wedge system that adjusts effective particle energies at isocenter. Lateral compensation performance was better than 1% for a homogeneous dose distribution when comparing irradiations of a stationary radiographic film and a moving film using motion compensation. The accuracy of longitudinal range compensation was well below 1 mm. Motion compensation with scanned particle beams is technically feasible with high precision
Beam-beam compensation studies in the Tevatron with electron lenses
Stancari, Giulio
2013-01-01
At the Fermilab Tevatron collider, we studied the feasibility of suppressing the antiproton head-on beam-beam tune spread using a magnetically confined 5-keV electron beam with Gaussian transverse profile overlapping with the circulating beam. When electron cooling of antiprotons was applied in regular Tevatron operations, the nonlinear head-on beam-beam effect on antiprotons was small. Therefore, we first focused on the operational aspects, such as beam alignment and stability, and on fundamental observations of tune shifts, tune spreads, lifetimes, and emittances. We also attempted two special collider stores with only 3 proton bunches colliding with 3 antiproton bunches, to suppress long-range forces and enhance head-on effects. We present here the results of this study and a comparison between numerical simulations and observations. These results contributed to the application of this compensation concept to RHIC at Brookhaven.
Robust Control for Static Loading of Electro-hydraulic Load Simulator with Friction Compensation
Institute of Scientific and Technical Information of China (English)
YAO Jianyong; JIAO Zongxia; YAO Bin
2012-01-01
Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation.Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems.The tracking performance of the static loading is studied in this paper.Firstly,the nonlinear mathematical models of the hydraulic load simulator are derived,and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance.Considering the effect of the friction,a LuGre model based friction compensation is synthesized,in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded.The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter.Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy.The tracking performance is summarized by a derived theorem.Experimental results are also obtained to verify the high performance nature of the proposed control strategy.
The damped oscillating propagation of the compensating self-accelerating beams
Liu, Wei-Wei; Yu, Pan-Pan; Wang, Hao-wei; Wang, Zi-qiang; Li, Yin-Mei
2016-01-01
We report a new form of compensating accelerating beam generated by amplitude modulation of the symmetric Airy beam (SAB) caustics with an exponential apodization mask. Our numerical study manifests that the compensating beam is with one main-lobe beam structure and can maintain the mean-intensity invariant both in the free space and loss media. Specially, the beam inherits the beamlets structure from the SAB and owns a novel damped oscillating propagation property. We also conduct a comparative study of its propagation property with that of the Airy beam theoretically. And by altering the signs of 2D masks, the main lobe of the compensating beam can be modulated to orientate in four different quadrants flexibly. The proposed compensating accelerating beam is anticipated to get special applications in particle manipulation or plasmas regions.
Siebert, Jan; Geimer, Marcus [Hrsg.
2016-01-01
In spite of their high technical maturity, load sensing systems (LS) have system-inherent energy losses that are largely due to the operation of parallel actuators with different loads at the same pressure level. Hereby, the pressure compensators of the system are crucial. So far, excessive hydraulic energy has been throttled at these compensators and been discharged as heat via the oil. The research project “Reduction of System Inherent Pressure Losses at Pressure Compensators of Hydraulic L...
Space Charge Compensation in the Linac4 Low Energy Beam Transport Line with Negative Hydrogen Ions
Valerio-Lizarraga, C; Leon-Monzon, I; Lettry, J; Midttun, O; Scrivens, R
2014-01-01
The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Tranport (LEBT) using the package IBSimu1, which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H- beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.
Issues in respiratory motion compensation during external-beam radiotherapy
International Nuclear Information System (INIS)
Purpose: To investigate how respiration influences the motion of lung and pancreas tumors and to relate the observations to treatment procedures intended to improve dose alignment by predicting the moving tumor's position from external breathing indicators. Methods and materials: Breathing characteristics for five healthy subjects were observed by optically tracking the displacement of the chest and abdomen, and by measuring tidal air volume with a spirometer. Fluoroscopic imaging of five radiotherapy patients detected the motion of lung and pancreas tumors synchronously with external breathing indicators. Results: The external and fluoroscopic data showed a wide range of behavior in the normal breathing pattern and its effects on the position of lung and pancreas tumors. This included transient phase shifts between two different external measures of breathing that diminished to zero over a period of minutes, modulated phase shifts between tumor and chest wall motion, and other complex phenomena. Conclusions: Respiratory compensation strategies that infer tumor position from external breathing signals, including methods of beam gating and dynamic beam tracking, require three-dimensional knowledge of the tumor's motion trajectory as well as the ability to detect and adapt to transient and continuously changing characteristics of respiratory motion during treatment
Tsai, Hsiu-Wen; Davenport, Paul W.
2014-01-01
Respiratory load compensation is a sensory-motor reflex generated in the brain stem respiratory neural network. The nucleus of the solitary tract (NTS) is thought to be the primary structure to process the respiratory load-related afferent activity and contribute to the modification of the breathing pattern by sending efferent projections to other structures in the brain stem respiratory neural network. The sensory pathway and motor responses of respiratory load compensation have been studied...
Dynamics of relativistic electron beam space charge compensation in a neutral gas
Energy Technology Data Exchange (ETDEWEB)
Kurilko, V.I.; Ognivenko, V.V.
1983-06-01
The dynamics of the space charge compensation of a relativistic electron beam with magnetized electrons as a result of ionization collisions of beam electrons and secondary ions with gas atoms has been studied theoretically. The analysis of calculation data shows that the neutral gas ionization by a relativistic electron beam leads to appearance of secondary ions which oscillate in a potential well of the electron beam space charge. It is shown that the density of ions formed is maximal in the beam center and drops to the beam periphery. As a result, the force compensation is possible only in the vicinity of a fixed coordinate which value grows with time.
Duration of Load Effects on Different Sized Timber Beams
DEFF Research Database (Denmark)
Andreasen, Lotte; Hoffmeyer, Preben
1997-01-01
This is the final report submitted to EC in connection with a project on duration of load. The report contains the results of the experimental work on duration of load for beams and notched beams of LVL and of glulam. The report also contains experimental results from duration of load experiments...
The E-lens test bench for RHIC beam-beam compensation
Energy Technology Data Exchange (ETDEWEB)
Gu X.; Altinbas, F.Z.; Aronson, J.; Beebe, E. et al
2012-05-20
To compensate for the beam-beam effects from the proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC), we are fabricating two electron lenses that we plan to install at RHIC IR10. Before installing the e-lenses, we are setting-up the e-lens test bench to test the electron gun, collector, GS1 coil, modulator, partial control system, some instrumentation, and the application software. Some e-lens power supplies, the electronics for current measurement will also be qualified on test bench. The test bench also was designed for measuring the properties of the cathode and the profile of the beam. In this paper, we introduce the layout and elements of the e-lens test bench; and we discuss its present status towards the end of this paper.
Key elements of space charge compensation on a low energy high intensity beam injector.
Peng, Shixiang; Lu, Pengnan; Ren, Haitao; Zhao, Jie; Chen, Jia; Xu, Yuan; Guo, Zhiyu; Chen, Jia'er; Zhao, Hongwei; Sun, Liangting
2013-03-01
Space charge effect (SCE) along the beam line will decrease beam quality. Space charge compensation (SCC) with extra gas injection is a high-efficiency method to reduce SCE. In this paper, we will report the experimental results on the beam profile, potential distribution, beam emittance, and beam transmission efficiency of a 35 keV∕90 mA H(+) beam and a 40 keV∕10 mA He(+) beam compensated by Ar∕Kr. The influence of gas type, gas flow, and injection location will be discussed. Emphasis is laid on the consideration of SCC when designing and commissioning a high intensity ion beam injector. Based on measured data, a new definition of space charge compensation degree is proposed. PMID:23556812
Key elements of space charge compensation on a low energy high intensity beam injector
Energy Technology Data Exchange (ETDEWEB)
Peng Shixiang; Lu Pengnan; Ren Haitao; Zhao Jie; Chen Jia; Xu Yuan; Guo Zhiyu; Chen Jia' er [Institution of Nuclear Science and Technology (INST), State Key Laboratory of Nuclear Physics and Technology (KLNPT), Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China); Zhao Hongwei; Sun Liangting [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)
2013-03-15
Space charge effect (SCE) along the beam line will decrease beam quality. Space charge compensation (SCC) with extra gas injection is a high-efficiency method to reduce SCE. In this paper, we will report the experimental results on the beam profile, potential distribution, beam emittance, and beam transmission efficiency of a 35 keV/90 mA H{sup +} beam and a 40 keV/10 mA He{sup +} beam compensated by Ar/Kr. The influence of gas type, gas flow, and injection location will be discussed. Emphasis is laid on the consideration of SCC when designing and commissioning a high intensity ion beam injector. Based on measured data, a new definition of space charge compensation degree is proposed.
Long-Range And Head-On Beam-Beam Compensation Studies in RHIC With Lessons for the LHC
Energy Technology Data Exchange (ETDEWEB)
Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; /Brookhaven; Dorda, U.; Koutchouk, J.P.; Sterbini, G.; Zimmermann, F.; /CERN; Kim, H.J.; Sen, T.; Shiltsev, V.; Valishev, A.; /Fermilab; Qiang, J.; /LBL, Berkeley; Kabel, A.; /SLAC
2011-11-28
Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.
An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation
AUTHOR|(CDS)2070952; Valishev, Aleksander; Shatilov, Dmitry
2015-01-01
In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical β∗ values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyze it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects.
An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation
Energy Technology Data Exchange (ETDEWEB)
Fartoukh, Stephane [CERN; Valishev, Alexander [Fermilab; Shatilov, Dmitry [BINP, Novosibirsk
2015-06-01
In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical $\\beta^{\\ast}$values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyze it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects.
Impact load mitigation in sandwich beams using local resonators
Sharma, B.; Sun, C.T.
2015-01-01
Dynamic response of sandwich beams with resonators embedded in the cores subjected to impact loads is studied. Using finite element models the effectiveness of various local resonator frequencies under a given impact load is compared to the behavior of an equivalent mass beam. It is shown that addition of appropriately chosen local resonators into the sandwich beam is an effective method of improving its flexural bending behavior under impact loads. The effect of a given local resonance frequ...
Mingchao Xia; Yanhui Mao
2013-01-01
Control strategies of D-STATCOM for unbalanced load compensation under internal and external disturbances were discussed. Linear control strategies do not have a satisfactory dynamic performance and become invalid under internal or external disturbances. To guarantee a good precision and robustness, a control strategy combining input-output feedback linearization technique with integral sliding mode control (ISMC) method was applied to D-STATCOM for unbalanced load compensation. The strategy ...
Symplectic Modeling of Beam Loading in Electromagnetic Cavities
Abell, Dan T; Webb, Stephen D
2016-01-01
Simulating beam loading in radiofrequency accelerating structures is critical for understanding higher-order mode effects on beam dynamics, such as beam break-up instability in energy recovery linacs. Full wave simulations of beam loading in radiofrequency structures are computationally expensive, while reduced models can ignore essential physics and can be difficult to generalize. We present a self-consistent algorithm derived from the least-action principle which can model an arbitrary number of cavity eigenmodes and with a generic beam distribution.
Shear Capacity of Concrete Beams under Sustained Loading
Sarkhosh, R.; Walraven, J.C.; Den Uijl, J.A.; Braam, C.R.
2013-01-01
Long-term tests on large-scale concrete beams without shear reinforcement, which are tested for more than two years under sustained loading close to the ultimate shear capacity (load ratio ranging from 87% to 95%) under climate controlled condition, show that sustained loading has no significant eff
Transient beam loading in the SLC Damping Rings
International Nuclear Information System (INIS)
Effects arising from heavy beam loading in the Stanford Linear Collider (SLC) Damping Rings are described. The stability of the rf system and particle beam is studied using a numerical model of the beam cavity interaction with multiple feedback loops. Nonlinearities of the power source are also considered. The effects of beam-induced transients and intensity jitter on the rf system are analyzed and used to determine stability tolerances for both high current and low current pulses
Studies of beam injection with a compensated bump and uncompensated bump in a synchrotron
International Nuclear Information System (INIS)
Synchrotron radiation sources Indus-1 and Indus-2 have a synchrotron as the common injector. A three kicker compensated bump injection scheme was employed for beam injection into this synchrotron. The stored beam current in the synchrotron is higher, when all the three kickers are operated at the same current than when kickers are operated at currents required to generate compensated bump. Beam dynamics studies have been done to understand why this happens. Theoretical studies indicate that higher stored current in the later case is attributed to smaller residual oscillations of injected beam. These studies also reveal that if the angle of the injected beam during beam injection is kept varying, the performance could be further improved. This is experimentally confirmed by injecting the beam on rising part of the injection septum magnet current pulse
Studies of beam injection with a compensated bump and uncompensated bump in a synchrotron
Energy Technology Data Exchange (ETDEWEB)
Akbar Fakhri, Ali; Prajapati, S. K.; Ghodke, A. D.; Singh, Gurnam [Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)
2013-08-15
Synchrotron radiation sources Indus-1 and Indus-2 have a synchrotron as the common injector. A three kicker compensated bump injection scheme was employed for beam injection into this synchrotron. The stored beam current in the synchrotron is higher, when all the three kickers are operated at the same current than when kickers are operated at currents required to generate compensated bump. Beam dynamics studies have been done to understand why this happens. Theoretical studies indicate that higher stored current in the later case is attributed to smaller residual oscillations of injected beam. These studies also reveal that if the angle of the injected beam during beam injection is kept varying, the performance could be further improved. This is experimentally confirmed by injecting the beam on rising part of the injection septum magnet current pulse.
Space charge compensation in the Linac4 low energy beam transport line with negative hydrogen ions
Energy Technology Data Exchange (ETDEWEB)
Valerio-Lizarraga, Cristhian A., E-mail: cristhian.alfonso.valerio.lizarraga@cern.ch [CERN, Geneva (Switzerland); Departamento de Investigación en Física, Universidad de Sonora, Hermosillo (Mexico); Lallement, Jean-Baptiste; Lettry, Jacques; Scrivens, Richard [CERN, Geneva (Switzerland); Leon-Monzon, Ildefonso [Facultad de Ciencias Fisico-Matematicas, Universidad Autónoma de Sinaloa, Culiacan (Mexico); Midttun, Øystein [CERN, Geneva (Switzerland); University of Oslo, Oslo (Norway)
2014-02-15
The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H{sup −} beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.
Charge and Current Compensation of Intense Charged Beams in Future Accelerators
Riege, H
1998-01-01
Proposals for future high-energy accelerators are characterized by demands for increasingly intense and energetic beams. The classical operation of high-current accelerators is severely constrained by collective electrodynamic phenomena, such as problems related to space-charge, to high-current flow, to beamstrahlung and pair production. These detrimental electrodynamic effects dominate the dynamic s and the collision interactions of high-intensity beams. With the introduction of soft space-charge and current compensation techniques utilizing low- to medium-energy lepton beams with charge polari ty opposite to that of the beams to be neutralized, all electromagnetic high-intensity limitations may be removed. The application of beam compensation is proposed for various sections of different ty pes of classical accelerator systems, such as for ion sources and the low-energy beam transport sections of ion linacs, for the crossing points of circular and linear colliders and for the final focii of ion beam fusion ...
Ion-optically driven depth compensation for ion beam tracking
International Nuclear Information System (INIS)
The beam delivery system for scanned carbon ion beam radiotherapy at GSI has been extended in research mode to irradiate moving targets. For beam tracking, the ion beam is adapted laterally as well as in range corresponding to the target's three dimensional (3D) motion. A beam tracking system with a motorized double wedge system for fast and accurate range adaptation has been developed. In addition to the current range adaptation system a much faster method for online energy modulation is being investigated where a fine focused ion beam is dynamically positioned, controlled by fast dipole magnets, on a small static wedge shaped absorber within the beam line. Experiments were performed at the therapy beam line to study the beam shift from central axis by the first dipole magnet up to the maximum limit where the beam can be deflected back to central axis by the second dipole magnet. Beam profiles were measured at different locations of the beam delivery system. The particle transmission was measured as well at the target position. Experiments were supported by Monte Carlo simulations for energy variation studies and for assessing the influence on beam profiles using MOCADI code
On compensating tune spread induced by space charge in bunched beams
Energy Technology Data Exchange (ETDEWEB)
Litvinenko V. N.; Wang, G.
2014-05-09
Space charge effects play significant role in modern-day accelerators. These effects frequently constrain attainable beam parameters in an accelerator, or, in an accelerator chain. They also could limit the luminosity of hadron colliders operating either at low energies or with a sub-TeV high brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. A number of schemes for compensating space charge effects in a coasting (e.g. continuous) hadron beam were proposed and some of them had been tested. Using a proper transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But all of these methods do not address the issue of tune spread compensation of a bunched hadron beam, e.g. the tune shift dependence on the longitudinal position inside the bunch. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present a number of practical examples of such system.
Analysis and Control of STATCOM/SMES Compensator in a Load Variation Conditions
Directory of Open Access Journals (Sweden)
Mahmoud Reza Shakarami
2014-01-01
Full Text Available The utilization of Flexible AC Transmission System (FACTS devices in a power system can potentially overcome limitations of the present mechanically controlled transmission system. Also, the advanced technology makes it possible to include new energy storage devices in the electrical power system. The integration of Superconducting Magnetic Energy Storage (SMES into Static Synchronous Compensator (STATCOM can lead to increase their flexibility to improve power system dynamic behavior by exchanging both active and reactive powers with power grids. This paper describes structure and behavior of STATCOM/SMES compensator in power systems. A control strategy based on direct Lyapanov method for compensator is used. Moreover, the performance of the STATCOM/SMES compensator in a load variation condition is evaluated by PSCAD/EMTDC software in test system. Also, SMES capacity effects on integrated compensator are investigated.
Energy Technology Data Exchange (ETDEWEB)
Segui-Chilet, S.; Gimeno-Sales, F.J.; Orts, S.; Alcaniz, M.; Masot, R. [Instituto de Tecnologia Electrica - Grupo de Tecnologia Electronica, Universidad Politecnica de Valencia, Camino de Vera 14, 46022 Valencia (Spain); Garcera, G.; Figueres, E. [Departamento de Ingenieria Electronica, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)
2007-09-15
This paper proposes a new definition of the unbalance power that allows the selective compensation of inefficiencies caused by linear loads by means of a three-phase shunt active power compensator (APC). Symmetrical components of current and voltage are used to evaluate the unbalance power in these systems and to define the compensating currents. The instantaneous power flows with unbalanced linear loads connected to a three-phase electrical system are analyzed following the normal procedure used for the quantification of the reactive power. Equations to calculate the unbalance power and the effective apparent power are obtained from the analysis of the instantaneous power flows. The output currents of the selective APC are defined using the instantaneous unbalance power approach. Power quantities and APC compensating current are defined for IEEE Std. 1459 and for the instantaneous unbalance power approach. Two examples are used to compare the power quantities and the APC operation. The main effects of unbalanced linear load and of fundamental voltage asymmetries are analyzed. Simulations of a shunt APC emphasize the advantages of the calculation of the compensating currents based on the proposed instantaneous unbalance power approach. A comparison with the results obtained by calculation of the compensating currents based on IEEE Std. 1459 is carried out. A new power factor is also defined and compared with other conventional definitions. (author)
A viscoelastic orthotropic Timoshenko beam subjected to general transverse loading
Directory of Open Access Journals (Sweden)
Adámek V.
2008-12-01
Full Text Available The investigation of lateral vibrations of a simply supported thin beam is the aim of this work. The analytical solution of the problem is derived based on the approximate Timoshenko beam theory for a general continuous loading acting on the upper beam face over the whole beam width and perpendicular to the beam axis. The material of the beam studied is assumed linear orthotropic viscoelastic. The generalized standard viscoelastic solid is chosen for representing of viscoelastic beam behaviour. Final system of partial integro-differential equations is solved by the standard method of integral transforms and resulting relations describing beam deflection, slope of the beam and corresponding stress and strain components are presented. Moreover, the derivation of final functions of beam deflection and slope of the beam for a specific impulse loading is presented and analytical results are compared with results obtained using numerical simulation in 2D (FEM. This confrontation shows very good agreement between results obtained. Furthermore, it was shown that the measure of agreement depends not only on the beam geometry.
Coupling Dynamics Interlip Coordination in Lower Lip Load Compensation
van Lieshout, Pascal; Neufeld, Chris
2014-01-01
Purpose: To study the effects of lower lip loading on lower and upper lip movements and their coordination to test predictions on coupling dynamics derived from studies in limb control. Method: Movement data were acquired using electromagnetic midsagittal articulography under 4 conditions: (a) without restrictions, serving as a baseline; (b) with…
Compensation for Adolescents’ School Mental Load by Physical Activity on Weekend Days
Directory of Open Access Journals (Sweden)
Michal Kudláček
2016-03-01
Full Text Available Introduction and objective: Increasing mental load and inadequate stress management significantly affect the efficiency, success and safety of the educational/working process in adolescents. The objective of this study is to determine the extent that adolescents compensate for their school mental load by physical activity (PA on weekend days and, thus, to contribute to the objective measurement of mental load in natural working conditions. Methods: A cross-sectional study was conducted between September 2013 and April 2014. A set of different methods was employed—self-administered questionnaire (IPAQ-long questionnaire, objective measurements—pedometers, and accelerometers (ActiTrainers. They was distributed to 548 students from 17 high schools. Participants’ mental load was assessed based on the difference between PA intensity and/or physical inactivity and heart rate range. Results: The participants with the highest mental load during school lessons do not compensate for this load by PA on weekend days. Conclusions: Adolescents need to be encouraged to be aware of their subjective mental load and to intentionally compensate for this load by PA on weekend days. It is necessary to support the process of adopting habits by sufficient physical literacy of students, as well as teachers, and by changes in the school program.
Lightweight Aggregate Concrete Beams. Load-bearing Capacity
DEFF Research Database (Denmark)
Larsen, Henning; Goltermann, Per; Ingholt, N.U.
1997-01-01
This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity.......This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity....
Impact load mitigation in sandwich beams using local resonators
Sharma, B
2015-01-01
Dynamic response of sandwich beams with resonators embedded in the cores subjected to impact loads is studied. Using finite element models the effectiveness of various local resonator frequencies under a given impact load is compared to the behavior of an equivalent mass beam. It is shown that addition of appropriately chosen local resonators into the sandwich beam is an effective method of improving its flexural bending behavior under impact loads. The effect of a given local resonance frequency under different impact load durations is also studied. It is demonstrated that the choice of appropriate local resonance frequency depends on the impact duration. Further, by performing transverse impact experiments, the finite element models are verified and the advantage of using internal resonators under impact loading conditions is demonstrated.
de Rooij, Michael Andrew; Steigerwald, Robert Louis; Delgado, Eladio Clemente
2008-12-16
Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.
Application of Load Compensation in Voltage Controllers of Large Generators in the Polish Power Grid
Directory of Open Access Journals (Sweden)
Bogdan Sobczak
2014-03-01
Full Text Available The Automatic Voltage Regulator normally controls the generator stator terminal voltage. Load compensation is used to control the voltage which is representative of the voltage at a point either within or external to the generator. In the Polish Power Grid (PPG compensation is ready to use in every AVR of a large generator, but it is utilized only in the case of generators operating at the same medium voltage buses. It is similar as in most European Power Grids. The compensator regulating the voltage at a point beyond the machine terminals has significant advantages in comparison to the slower secondary Voltage and Reactive Power Control System (ARNE1. The compensation stiffens the EHV grid, which leads to improved voltage quality in the distribution grid. This effect may be particularly important in the context of the dynamic development of wind and solar energy.
Chung, Ting-Yi; Huang, Szu-Jung; Fu, Huang-Wen; Chang, Ho-Ping; Chang, Cheng-Hsiang; Hwang, Ching-Shiang
2016-08-01
The effect of an APPLE II-type elliptically polarized undulator (EPU) on the beam dynamics were investigated using active and passive methods. To reduce the tune shift and improve the injection efficiency, dynamic multipole errors were compensated using L-shaped iron shims, which resulted in stable top-up operation for a minimum gap. The skew quadrupole error was compensated using a multipole corrector, which was located downstream of the EPU for minimizing betatron coupling, and it ensured the enhancement of the synchrotron radiation brightness. The investigation methods, a numerical simulation algorithm, a multipole error correction method, and the beam-based measurement results are discussed.
Directory of Open Access Journals (Sweden)
Mingchao Xia
2013-01-01
Full Text Available Control strategies of D-STATCOM for unbalanced load compensation under internal and external disturbances were discussed. Linear control strategies do not have a satisfactory dynamic performance and become invalid under internal or external disturbances. To guarantee a good precision and robustness, a control strategy combining input-output feedback linearization technique with integral sliding mode control (ISMC method was applied to D-STATCOM for unbalanced load compensation. The strategy has features of simple structure and is easy to implement. A 10 MVar/10 kV D-STATCOM simulation system was built in PSCAD/EMTDC to verify the effectiveness and robustness of the control strategy proposed. Simulation results show that the control strategy can compensate reactive power and eliminate unbalance simultaneously under various disturbances.
Effect of ion compensation of the beam space charge on gyrotron operation
Energy Technology Data Exchange (ETDEWEB)
Fokin, A. P.; Glyavin, M. Yu. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Nusinovich, G. S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)
2015-04-15
In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ion compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.
Enhanced control strategy for MMC-based STATCOM for unbalanced load compensation
DEFF Research Database (Denmark)
Nieves, M.; Maza, J.M.; Mauricio, J.M.;
2014-01-01
as required for load unbalance compensation. This paper proposes an improved balancing strategy for the delta configuration to overcome this situation based on the injection of a third harmonic zero sequence current. Simulation results have proved the effectiveness of the proposal even where different...
Partial loss compensation in dielectric-loaded plasmonic waveguides at near infra-red wavelengths
DEFF Research Database (Denmark)
Garcia, Cesar; Coello, Victor; Han, Zhanghua;
2012-01-01
We report on the fabrication and characterization of straight dielectric-loaded surface plasmon polaritons waveguides doped with lead-sulfide quantum dots as a near infra-red gain medium. A loss compensation of ~33% (an optical gain of ~143 cm^−1) was observed in the guided mode. The mode propaga...
On Linear Power Factor Compensation, Power Equalization and Cyclo–dissipativity of Nonlinear Loads
Puerto-Flores, Dunstano del; Scherpen, Jacquelien M.A.; Ortega, Romeo
2010-01-01
The main contribution of this paper is an extension of the recently introduced result that recasts the problem of power factor compensation for nonlinear loads with non-sinusoidal source voltage in terms of the property of cyclo–dissipativity. Using the cyclo–dissipativity framework the classical ca
Energy recuperation of intense proton beam compensated by slow electrons
International Nuclear Information System (INIS)
Experimental studies of direct transformation (recuperation) of intense ion beam energy are described. In a recuperator low-energy electrons of a beam are separated by a grid unit and ions are detected by one of the three types of collectors: plane, ''Faraday cylinder'' with a grid in the input hole and without it. The transformation of proton beam energy with current density up to 150 mA/cm2 at current pulse duration of 300 μ and power of ∼ 0.5 kW is realized with the efficiency of 70%, at power up to 30 kW - with the efficiency of about 50%. The investigation results can be used for the development of recuperation systems in thermonuclear facilities
Fu, Shiyao; Zhang, Shikun; Wang, Tonglu; Gao, Chunqing
2016-07-15
We propose a scheme that uses a probe Gaussian beam and the Gerchberg-Saxton (GS) algorithm to realize the pre-turbulence compensation of beams carrying orbital angular momentum (OAM). In the experiment, spatial light modulators are utilized to simulate the turbulent atmosphere and upload the retrieval holograms. A probe Gaussian beam is used to detect the turbulence. Then, the retrieval holograms, which can correct the phase distortion of the OAM beams, are obtained by the GS algorithm. The experimental results show that single or multiplexed OAM beams can be compensated well. The compensation performances under different iterations are also analyzed. PMID:27420491
A Statistical Approach to Motion Compensated Cone Beam Reconstruction
DEFF Research Database (Denmark)
Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus
2010-01-01
One of the problems arising in radiotherapy planning is the quality of CT planning data. In the following attention is giving to the cone-beam scanning geometry where reconstruction of a 3D volume based on 2D projections, using the classic Feldkamp-Davis-Kress (FDK) algorithm requires a large...
A statistical approach to motion compensated cone-beam
DEFF Research Database (Denmark)
Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus
One of the problems arising in radiotherapy planning is the quality of CT planning data. In the following attention is giving to the cone-beam scanning geometry where reconstruction of a 3D volume based on 2D projections, using the classic Feldkamp-Davis-Kress (FDK) algorithm requires a large...
Institute of Scientific and Technical Information of China (English)
CHANG Min; PENG Dan; XU Ke-xin
2007-01-01
A double beam near-infrared spectrometer is developed to compensate the water absorption and instrumental drift in intensity. The spectrometer maybe used for both single and double beam measurements, and the two operation modes are compared. The results show that the double beam technique eliminates instrumental drift in the single beam measurement and therefore the stability of the system increases by more than 20%. The compensation of the double beam system on water absorption is verified by the measurement of fat content in milk. The results show that the spectrum data based on double beam mode get better calibration model and lower prediction error than traditional single beam mode.
Automatic compensation of antenna beam roll-off in SAR images.
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter
2006-04-01
The effects of a non-uniform antenna beam are sometimes visible in Synthetic Aperture Radar (SAR) images. This might be due to near-range operation, wide scenes, or inadequate antenna pointing accuracy. The effects can be mitigated in the SAR image by fitting very a simple model to the illumination profile and compensating the pixel brightness accordingly, in an automated fashion. This is accomplished without a detailed antenna pattern calibration, and allows for drift in the antenna beam alignments.
Tada, M; Mitani, Yasunori; K. Tsuji
1995-01-01
This paper describes a load change compensation by a superconducting magnetic energy storage (SMES) which is assumed to be installed in a power system for power system stabilization. A simultaneous control strategy of SMES for load change compensation as well as for power system stabilization in a longitudinally interconnected power system is derived. Several numerical examples demonstrate the significant effectiveness of the SMES
Field Test Result of 10MVA/20MJ SMES for Load Fluctuation Compensation
Nagaya, Shigeo; Nagata, Tatsuya; Hirano, Naoki; Tamada, Tsutomu; Nijo, Yoshio; Katagiri, Toshio; Yamane, Minoru
SMES of the10,000kW for the power control in power system has been manufactured, and connected to a real power grid. In addition, innovative basic researches, for example, low cost converter, maintenance-free cryo-coolers, inter-locks system and so on, have also been developed. The SMES was installed in the metal rolling factory with hydro power plant. Field test has been carried out for load fluctuation compensation. SMES was able to compensate for the active power according to the fluctuating load, and confirm the situation with a smooth load change of 11kV bus of hydro power stations. In this paper, field test results are presented.
A Novel Hybrid Dstatcom Topology for Load Compensation with Non-Stiff Source
Directory of Open Access Journals (Sweden)
M Guru Dasthagiri Reddy
2014-09-01
Full Text Available The distribution static compensator (DSTATCOM is a shunt active filter, which injects currents into the point of common coupling (PCC (the common point where load, source, and DSTATCOM are connected such that the harmonic filtering, power factor correction, and load balancing can be achieved. The distribution static compensator (DSTATCOM is used for load compensation in power distribution network. A new topology for DSTATCOM applications with non-stiff source is proposed. The proposed topology enables DSTATCOM to have a reduced dc-link voltage without compromising the compensation capability. It uses a series capacitor along with the interfacing inductor and a shunt filter capacitor. With the reduction in dc-link voltage, the average switching frequency of the insulated gate bipolar transistor switches of the D-STATCOM is also reduced. Consequently, the switching losses in the inverter are reduced. Detailed design aspects of the series and shunt capacitors are discussed in this paper. A simulation study of the proposed topology has been carried out using MATLAB environment and the results analyzed.
Alekseev, G. A.; Apokin, V. D.; Buyanov, O. V.
The results on measuring the basic characteristics of a compensated lead calorimeter (NEPTUN experiment) in a hadron and electron beam are presented. A prototype consisting of 30 modulus was used in the measurements. The energy resolution follows the dependence approximately = 57%/sq. root of E, the detector uniformity is (+-)5%, the measured e/h ratio is close to unity.
AUTHOR|(SzGeCERN)390904; Papaphilippou, Yannis; Shatilov, Dmitry
2015-01-01
Colliding bunch trains in a circular collider demands a certain crossing angle in order to separate the two beams transversely after the collision. The magnitude of this crossing angle is a complicated function of the bunch charge, the number of long-range beam-beam interactions, of β* and type of optics (flat or round), and possible compensation or additive effects between several low-β insertions in the ring depending on the orientation of the crossing plane at each interaction point. About 15 years ago, the use of current bearing wires was proposed at CERN in order to mitigate the longrange beam-beam effects, therefore offering the possibility to minimize the crossing angle with all the beneficial effects this might have: on the luminosity performance by reducing the need for crab-cavities or lowering their voltage, on the required aperture of the final focus magnets, on the strength of the orbit corrector involved in the crossing bumps, and finally on the heat load and radiation dose deposited in the fi...
Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems
DEFF Research Database (Denmark)
Preindl, Matthias; Schaltz, Erik
2011-01-01
The widely used cascade speed and torque controllers have a limited control performance in most high power applications due to the low switching frequency of power electronic converters and the convenience to avoid speed overshoots and oscillations for lifetime considerations. Model Predictive...... further improve dynamic behavior. It compensates the load torque influence on the speed control setting a feed forward torque reference value. The benefits are twice; the speed controller reaches the speed reference value without offsets which would need to be compensated by an integrator and a better...
RF broad-beam low-energy ion source with electron compensation
Directory of Open Access Journals (Sweden)
Zykov A. V.
2010-03-01
Full Text Available Characteristics of single-grid RF ion source with 250 mm beam diameter and 1A beam current have been studied. Energy distribution functions of electrons and ions emitted by the source have been measured. It is shown that the emitted electron current is sufficient for full ion beam current compensation. The technique of ion to electron current ratio control allowing to change this ratio in wide range is proposed. Using the ICP in the source allows to rich high current density in the low ion energy range with the possibility of independent control of ion energy and current density.
Energy Technology Data Exchange (ETDEWEB)
Shiltsev, V.; Alexahin, Y.; Kamerdzhiev, V.; Kuznetsov, G.; Zhang, X.L.; /Fermilab; Bishofberger, K.; /Los Alamos
2007-06-01
Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams are significant sources of beam loss and lifetime limitations in the Tevatron Collider Run II (2001-present). We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in high energy physics (HEP) operation, predict the performance for planned luminosity upgrades and discuss ways to improve it.
Load beam unit replaceable inserts for dry coal extrusion pumps
Saunders, Timothy; Brady, John D.
2012-11-13
A track assembly for a particulate material extrusion pump according to an exemplary aspect of the present disclosure includes a link assembly with a roller bearing. An insert mounted to a load beam located such that the roller bearing contacts the insert.
Dynamic Response of Axially Loaded Euler-Bernoulli Beams
DEFF Research Database (Denmark)
Bayat, M.; Barari, Amin; Shahidi, M.
2011-01-01
The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibration behavior of Euler-Bernoulli beams subjected to axial loads. Analytical...
Xereas, George; Chodavarapu, Vamsy P.
2014-03-01
Frequency references are used in almost every modern electronic device including mobile phones, personal computers, and scientific and medical instrumentation. With modern consumer mobile devices imposing stringent requirements of low cost, low complexity, compact system integration and low power consumption, there has been significant interest to develop batch-manufactured MEMS resonators. An important challenge for MEMS resonators is to match the frequency and temperature stability of quartz resonators. We present 1MHz and 20MHz temperature compensated Free-Free beam MEMS resonators developed using PolyMUMPS, which is a commercial multi-user process available from MEMSCAP. We introduce a novel temperature compensation technique that enables high frequency stability over a wide temperature range. We used three strategies: passive compensation by using a structural gold (Au) layer on the resonator, active compensation through using a heater element, and a Free-Free beam design that minimizes the effects of thermal mismatch between the vibrating structure and the substrate. Detailed electro-mechanical simulations were performed to evaluate the frequency response and Quality Factor (Q). Specifically, for the 20MHz device, a Q of 10,000 was obtained for the passive compensated design. Finite Element Modeling (FEM) simulations were used to evaluate the Temperature Coefficient of frequency (TCf) of the resonators between -50°C and 125°C which yielded +0.638 ppm/°C for the active compensated, compared to -1.66 ppm/°C for the passively compensated design and -8.48 ppm/°C for uncompensated design for the 20MHz device. Electro-thermo-mechanical simulations showed that the heater element was capable of increasing the temperature of the resonators by approximately 53°C with an applied voltage of 10V and power consumption of 8.42 mW.
Mechatronic FEM model of an electromagnetic-force-compensated load cell
Weis, Hanna; Hilbrunner, Falko; Fröhlich, Thomas; Jäger, Gerd
2012-07-01
In this paper, a mechatronic model for an electromagnetic-force-compensated (EMC) load cell is presented. Designed in ANSYS Mechanical APDL®, the model consists of two modules: the mechanical behaviour of the load cell is represented by a FEM model. The electronic and the electromagnetic parts, consisting of a position indicator, controller and electromagnetic actuator, are implemented into the model as a set of differential equations via ANSYS Parametric Design Language (APDL). Optimization of the mechanical, electromagnetic and controller components can be performed using this model, as well as experiments to determine the sensitivity of the complete system to changes of environmental properties, e.g., the stiffness of the support.
Mechatronic FEM model of an electromagnetic-force-compensated load cell
International Nuclear Information System (INIS)
In this paper, a mechatronic model for an electromagnetic-force-compensated (EMC) load cell is presented. Designed in ANSYS Mechanical APDL®, the model consists of two modules: the mechanical behaviour of the load cell is represented by a FEM model. The electronic and the electromagnetic parts, consisting of a position indicator, controller and electromagnetic actuator, are implemented into the model as a set of differential equations via ANSYS Parametric Design Language (APDL). Optimization of the mechanical, electromagnetic and controller components can be performed using this model, as well as experiments to determine the sensitivity of the complete system to changes of environmental properties, e.g., the stiffness of the support. (paper)
Intelligent power factor compensation equipment of three phase low voltage loads
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
An intelligent power factor correction scheme is presented for three phase low power factor loads. This new scheme is able to perform individual phase sensing of parameters by monitoring at all times to sense a change in system parameters and affects individual phase correction by applying the exact amount of reactive components needed for each phase, and can also reduce negative sequence current caused by the load to improve system balance. An optimization criterion is used for the proper calculation of reactive power steps in a power compensation installation of capacitor banks. The criterion is enabled by sampling measurements performed on the electrical plant examined within specific interval of time.
Energy Technology Data Exchange (ETDEWEB)
Roy, Surajit; Ladpli, Purim; Chang, Fu-Kuo
2015-09-01
Accurate interpretation of in-situ piezoelectric sensor signals is a challenging task. This article presents the development of a numerical compensation model based on physical insight to address the influence of structural loads on piezo-sensor signals. The model requires knowledge of in-situ strain and temperature distribution in a structure while acquiring sensor signals. The parameters of the numerical model are obtained using experiments on flat aluminum plate under uniaxial tensile loading. It is shown that the model parameters obtained experimentally can be used for different structures, and sensor layout. Furthermore, the combined effects of load and temperature on the piezo-sensor response are also investigated and it is observed that both of these factors have a coupled effect on the sensor signals. It is proposed to obtain compensation model parameters under a range of operating temperatures to address this coupling effect. An important outcome of this study is a new load monitoring concept using in-situ piezoelectric sensor signals to track changes in the load paths in a structure.
Roy, Surajit; Ladpli, Purim; Chang, Fu-Kuo
2015-09-01
Accurate interpretation of in-situ piezoelectric sensor signals is a challenging task. This paper presents the development of a numerical compensation model based on physical insight to address the influence of structural loads on piezo-sensor signals. The model requires knowledge of in-situ strain and temperature distribution in a structure while acquiring piezoelectric sensor signals. The parameters of the numerical model are obtained using experiments on flat aluminum plate under uniaxial tensile loading. It is shown that the model parameters obtained experimentally can be used for different structures, and sensor layout. Furthermore, the combined effects of load and temperature on the piezo-sensor response are also investigated and it is observed that both of these factors have a coupled effect on the sensor signals. It is proposed to obtain compensation model parameters under a range of operating temperatures to address this coupling effect. An important outcome of this study is a new load monitoring concept using in-situ piezoelectric sensor signals to track changes in the load paths in a structure.
Space charge compensation on the low energy beam transport of Linac4
AUTHOR|(SzGeCERN)733270; Scrivens, Richard; Jesus Castillo, Santos
Part of the upgrade program in the injector chains of the CERN accelerator complex is the replacement of the the proton accelerator Linac2 for the brand new Linac4 which will accelerate H$^-$ and its main goal is to increase the beam intensity in the next sections of the LHC accelerator chain. The Linac4 is now under commissioning and will use several ion sources to produce high intensity unbunched H$^-$ beams with different properties, and the low energy beam transport (LEBT) is the system in charge of match all these different beams to the Radio frequency quadrupole (RFQ). The space charge forces that spread the beam ions apart of each other and cause emittance growth limits the maximum intensity that can be transported in the LEBT, but the space charge of intense unbunched ion beams can be compensated by the generated ions by the impact ionization of the residual gas, which creates a source of secondary particles inside the beam pipe. For negative ion beams, the effect of the beam electric field is to ex...
Prediction of Load Carrying Capacity of Corroded Reinforced Concrete Beam
Institute of Scientific and Technical Information of China (English)
范颖芳; 周晶; 冯新
2004-01-01
A novel method for prediction of the load carrying capacity of a corroded reinforced concrete beam (CRCB) is presented in the paper. Nine reinforced concrete beams, which had been working in an aggressive environment for more than 10 years, were tested in the laboratory. Comprehensive tests, including flexural test, strength test for corroded concrete and rusty rebar, and pullout test for bond strength between concrete and rebar, were conducted. The flexural test results of CRCBs reveal that the distribution of surface cracks on the beams shows a fractal behavior. The relationship between the fractal dimensions and mechanical properties of CRCBs is then studied. A prediction model based on artificial neural network (ANN) is established by the use of the fractal dimension as the corrosion index, together with the basic information of the beam. The validity of the prediction model is demonstrated through the experimental data, and satisfactory results are achieved.
Development of low energy ion beam system for space charge compensation experiments
International Nuclear Information System (INIS)
A low energy ion beam system for space charge compensation (SCC) experiments was developed and evaluated. This system was designed for observation of SCC of a positive ion beam with an electron beam. The system consisted of the ion source chamber and the SCC experiment chamber. The ion source chamber was equipped with the compact microwave ion source for low voltage extraction. Ion current at initial position of the analysis chamber was 84 μA at extraction voltage of 500 V, and satisfied a condition to observe the SCC effect clearly. In order to evaluate the SCC, we measured the arrival ion current by supplying thermionic electrons, which were extracted from a tungsten filament driven by ac voltage. As the electron supply, the arrival ion current increased from 40 to 68 μA at the potential of filament of +3 eV which produced the thermionic electron with extremely low energy extracted by space charge of the ion beam
Liu, Wei; Li, Chao; Sun, Zhao-Yang; Zhao, Yu; Wu, Shi-You; Fang, Guang-You
2016-08-01
In the terahertz (THz) band, the inherent shake of the human body may strongly impair the image quality of a beam scanning single frequency holography system for personnel screening. To realize accurate shake compensation in imaging processing, it is quite necessary to develop a high-precision measure system. However, in many cases, different parts of a human body may shake to different extents, resulting in greatly increasing the difficulty in conducting a reasonable measurement of body shake errors for image reconstruction. In this paper, a body shake error compensation algorithm based on the raw data is proposed. To analyze the effect of the body shake on the raw data, a model of echoed signal is rebuilt with considering both the beam scanning mode and the body shake. According to the rebuilt signal model, we derive the body shake error estimated method to compensate for the phase error. Simulation on the reconstruction of point targets with shake errors and proof-of-principle experiments on the human body in the 0.2-THz band are both performed to confirm the effectiveness of the body shake compensation algorithm proposed. Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. YYYJ-1123).
Monte Carlo simulation of spectrum changes in a photon beam due to a brass compensator
Energy Technology Data Exchange (ETDEWEB)
Custidiano, E.R., E-mail: ernesto7661@gmail.com [Department of Physics, FaCENA, UNNE, Av., Libertad 5470, C.P.3400, Corrientes (Argentina); Valenzuela, M.R., E-mail: meraqval@gmail.com [Department of Physics, FaCENA, UNNE, Av., Libertad 5470, C.P.3400, Corrientes (Argentina); Dumont, J.L., E-mail: Joseluis.Dumont@elekta.com [Elekta CMS Software, St.Louis, MO (United States); McDonnell, J., E-mail: josemc@express.com.ar [Cumbres Institute, Riobamba 1745, C.P.2000, Rosario, Santa Fe (Argentina); Rene, L, E-mail: luismrene@gmail.com [Radiotherapy Center, Crespo 953, C.P.2000, Rosario, Santa Fe (Argentina); Rodriguez Aguirre, J.M., E-mail: juakcho@gmail.com [Department of Physics, FaCENA, UNNE, Av., Libertad 5470, C.P.3400, Corrientes (Argentina)
2011-06-15
Monte Carlo simulations were used to study the changes in the incident spectrum when a poly-energetic photon beam passes through a static brass compensator. The simulated photon beam spectrum was evaluated by comparing it against the incident spectra. We also discriminated the changes in the transmitted spectrum produced by each of the microscopic processes. (i.e. Rayleigh scattering, photoelectric effect, Compton scattering, and pair production). The results show that the relevant process in the energy range considered is the Compton Effect, as expected for composite materials of intermediate atomic number and energy range considered.
Stud Reinforcement in Beam-Column Joints under Seismic Loads
Ibrahim, Hatem Hassan Ali
Current codes recommend large amounts of shear reinforcement for reinforced concrete beam-column joints causing significant congestion. This research aims at investigating experimentally and numerically the efficiency of using studs with a head at each end in lieu of conventional closed hoops in reinforced concrete beam-column joints. The proposed reinforcement reduces congestion and ensures easier assembly of the reinforcing cage, saving labour cost and enhancing performance of the joint. Based on this research, a recommended arrangement and detailing of headed studs and their design for exterior beam-column joint are presented. The experimental investigation consisted of testing ten full-scale beam-column joint specimens under quasi-static cyclic loading. The specimens represented an exterior beam-column joint subassembly isolated at the points of contra-flexure from a typical multi-storey, multi-bay reinforced concrete frame. A test setup was developed to simulate the lateral inter-storey drift. The test parameters included: the type, arrangement and amount of shear reinforcement, the load history and rate of loading, and the amount of reinforcement for out-of-plane confinement of the joint. Envelopes of the hysteretic behaviour of the specimens and the joint deformation under shear stress are presented. The stiffness degradation, the strain levels in the joint reinforcement, the contribution of joint, beam, and column to the inter-storey drift, and the energy dissipation were compared. All the test specimens reinforced with headed studs in the joint achieved considerable enhancement in their behaviour under cyclic loads and exhibited a performance close to that of a joint reinforced with closed hoops and cross ties according to the code. All the specimens with adequate out-of-plane confinement had an equivalent behaviour compared with the code-based specimen and achieved a desirable mode of failure. Use of double-headed studs proved to be a viable option for
Dumazert, Jonathan; Coulon, Romain; Bertrand, Guillaume H. V.; Normand, Stéphane; Méchin, Laurence; Hamel, Matthieu
2016-05-01
Gadolinium-covered modified plastic scintillators show a high potential for the deployment of cost-effective neutron detectors. Taking advantage of the low-energy photon and electron signature of thermal neutron captures in gadolinium-155 and gadolinium-157 however requires a background correction. In order to display a trustable rate, dual compensation schemes appear as an alternative to Pulse Shape Discrimination. This paper presents the application of such a compensation scheme to a two-bismuth loaded plastic scintillator system. A detection scintillator interacts with incident photon and fast neutron radiations and is covered with a gadolinium converter to become thermal neutron-sensitive as well. In the meantime, an identical compensation scintillator, covered with terbium, solely interacts with the photon and fast neutron part of incident radiations. After the acquisition and the treatment of the counting signals from both sensors, a hypothesis test determines whether the resulting count rate after subtraction falls into statistical fluctuations or provides a robust image of neutron activity. A laboratory prototype is tested under both photon and neutron radiations, allowing us to investigate the performance of the overall compensation system. The study reveals satisfactory results in terms of robustness to a cesium-137 background and in terms of sensitivity in presence of a californium-252 source.
A method to compensate the energy loss of a continuous stacked beam with a large momentum spread
International Nuclear Information System (INIS)
A system of rectangular drift tube loaded cavities resonating in the TE 101 mode combined with a cyclic scaling guide field can be used to accelerate an unbunched beam of charged particles. The system is superior to phase displacement because the cavities are driven at a fixed frequency with certain phase differences between each other. The range of particle momenta is limited by rf-knock out. Rf-induced betatron oscillations and phase dependent momentum changes can be compensated by means of sixteen cavities on the circumference of the accelerator. The amplitude of the betatron oscillations and the energy gain were calculated numerically for storage devices consisting of a spiral-sector FFAG guide field and one or sixteen cavities, respectively, using measured rf-feld data. The systems seem to be practical only for electrons with an energy up to 100 MeV. The rf-system works within an energy width of several MeV. (Auth.)
Elasticity solution of laminated beams subjected to thermo-loads
Institute of Scientific and Technical Information of China (English)
钱海; 周叮; 刘伟庆; 方海
2015-01-01
According to the two-dimensional (2-D) thermo-elasticity theory, the exact elasticity solution of the simply supported laminated beams subjected to thermo-loads was studied. An analytical method was presented to obtain the temperature, displacement and stress fields in the beam. Firstly, the general solutions of temperature, displacements and stresses for a single-layered simply supported beam were obtained by solving the 2-D heat conduction equation and the 2-D elasticity equations, respectively. Then, based on the continuity of temperature, heat flux, displacements and stresses on the interface of two adjacent layers, the formulae of temperature, displacements and stresses between the lowest layer and the top layer of the beam were derived out in a recurrent manner. Finally, the unknown coefficients in the solutions were determined by the use of the upper surface and lower surface conditions of the beam. The distributions of temperature, displacement and stress in the beam were obtained by substituting these coefficients back to the recurrence formulae and the solutions. The excellent convergence of the present method has been demonstrated and the results obtained by the present method agree well with those from the finite element method. The effects of surface temperatures, thickness, layer number and material properties of the plate on the temperature distribution were discussed in detail. Numerical results reveal that the displacements and stresses monotonically increase with the increase of surface temperatures. In particular, the horizontal stresses are discontinuous at the interface.
Electron Lenses for compensation of beam-beam effects Tevatron, RHIC, LHC
Shiltsev, V
2008-01-01
Since previous BEAM’06 workshop a year ago, significant progress has been made in the field of beambeam compensation (BBC) – it has been experimentally demonstrated that both Tevatron Electron Lenses (TEL) significantly improve proton and luminosity lifetimes in high-luminosity stores. This article summarizes these results and discusses prospects of the BBC in Tevatron, RHIC and LHC.
Chen, Junchi; Peng, Yujie; Su, Hongpeng; Leng, Yuxin
2016-06-01
To compensate for the gain saturation effect in the high-energy laser amplifier, a modified polarization beam combination (PBC) method is introduced to reshape temporal waveform of the injected laser pulse to obtain a controlled high-energy laser pulse shape after amplification. One linearly polarized beam is divided into two orthogonal polarized beams, which spatially recombine together collinearly after propagating different optical paths with relative time delay in PBC structure. The obtained beam with polarization direction being rotated by the following half wave plate is divided and combined again to reform a new beam in another modified polarization beam structure. The reformed beam is injected into three cascaded laser amplifiers. The amplified pulse shape can be controlled by the incident pulse shape and amplifier gain, which is agreeable to the simulation by the Frank-Nodvik equations. Based on the simple method, the various temporal waveform of output pulse with tunable 7 to 20 ns pulse duration can be obtained without interferometric fringes.
Chen, Junchi; Peng, Yujie; Su, Hongpeng; Leng, Yuxin
2016-06-01
To compensate for the gain saturation effect in the high-energy laser amplifier, a modified polarization beam combination (PBC) method is introduced to reshape temporal waveform of the injected laser pulse to obtain a controlled high-energy laser pulse shape after amplification. One linearly polarized beam is divided into two orthogonal polarized beams, which spatially recombine together collinearly after propagating different optical paths with relative time delay in PBC structure. The obtained beam with polarization direction being rotated by the following half wave plate is divided and combined again to reform a new beam in another modified polarization beam structure. The reformed beam is injected into three cascaded laser amplifiers. The amplified pulse shape can be controlled by the incident pulse shape and amplifier gain, which is agreeable to the simulation by the Frank-Nodvik equations. Based on the simple method, the various temporal waveform of output pulse with tunable 7 to 20 ns pulse duration can be obtained without interferometric fringes.
High Resolution Beam Orbit Measurement Electronics based on Compensated Diode Detectors
Gasior, M
2010-01-01
A high resolution beam position monitor (BPM) electronics based on diode peak detectors has been developed at CERN. The circuit processes the BPM electrode signals independently, converting the short beam pulses into slowly varying signals which can be digitized with high resolution ADCs operating in the kHz range or even measured with a DC voltmeter. For signals with peak amplitudes larger than some hundred mV the non-linear forward voltage of the diodes is compensated by a simple network using signals from two peak detectors, one with a single and the second with two diodes in series. This contribution presents results obtained with the first prototype in the laboratory and with the CERN-SPS beam. Ongoing development and possible future applications of the technique are also discussed.
Energy Technology Data Exchange (ETDEWEB)
Fuse, H., E-mail: fuseh@ipu.ac.jp [Department of Radiological Sciences, Ibaraki Prefectural University of Health Science, Amimachi, Inashiki-gun, Ibaraki (Japan); Suzuki, K.; Shida, K.; Takahashi, H.; Kobayashi, D.; Seki, M. [Department of Radiology, University of Tsukuba Hospital, Tsukuba city, Ibaraki (Japan); Mori, Y.; Sakae, T. [Proton Medical Research Center, University of Tsukuba, Tsukuba city, Ibaraki (Japan); Isobe, T. [Department of Radiation Oncology, University of Tsukuba, Tsukuba city, Ibaraki (Japan); Okumura, T.; Sakurai, H. [Proton Medical Research Center, University of Tsukuba, Tsukuba city, Ibaraki (Japan); Department of Radiation Oncology, University of Tsukuba, Tsukuba city, Ibaraki (Japan)
2014-06-15
Total skin electron beam is a specialized technique that involves irradiating the entire skin from the skin surface to only a few millimetres in depth. In the Stanford technique, the patient is in a standing position and six different directional positions are used during treatment. Our technique uses large electron beams in six directions with an inclinable couch on motorized table and a compensating filter was also used to spread the electron beam and move its intensity peak. Dose uniformity measurements were performed using Gafchromic films which indicated that the surface dose was 2.04 ± 0.05 Gy. This technique can ensure the dose reproducibility because the patient is fixed in place using an inclinable couch on a motorized table.
Study of the transient effects of the space charge compensation on the dynamics of an intense beam
International Nuclear Information System (INIS)
A main interest in the design of ion accelerators is the control of the dynamics of intense beams at low energy. This dynamics is dominated by nonlinear effects of the Space Charge (SC) field. This SC field induces a halo formation which can induce losses along the transport. Once ionized by the beam, the residual gas, diffused by the source and produced by the desorption of the vacuum chamber of the accelerator, contributes to the production of electrons and ions. According to their sign of charge compared to the beam, these particles will be repelled or confined. The accumulation of particles in the beam contributes to the compensation of the SC field. However, this neutralization induces other non linearity which are dependent on time. This thesis presents an experimental and theoretical work of the SC compensation for ion beams (H+ and H-). The dynamics of these beams is modelled by a new PIC code, CARTAGO, ensuring the coupling between the created plasma and the studied beams. A single-particle study introduces the dynamics of the plasma in presence of the SC field and of an external magnetic field. The modeling of the compensation with the 1D version of CARTAGO code gave the establishment times and the compensation degrees for several cases of beams and various gas pressures. The compensation of a protons beam was studied more particularly in the low-energy line of the Injector of Protons of High Intensity (IPHI) at Saclay. Simulations show an over-compensation of the space charge inside the focusing solenoid and outside the compensation is only partial. Experimental confrontations of the 2D(r,z) modeling results in a part of this line are also detailed. (author)
Improvements of the undulator spectral performance by compensating the backing beam deflection
Wang, C; Chang, L H; Chang, C H; Fan, T C; Bach, H; Blomqvist, I
2002-01-01
This study thoroughly examines how the backing beam deflection affects the undulator spectral performance. Reduction of the undulator spectral intensity owing to backing beam deflection is analytically evaluated based on plane-wave approximation. The results reveal that the amplitude and the slope of the backing beam deflection affect the undulator spectral performance. Provided is a novel figure-of-merit, rms of the regressed accumulated gap deviation, to determine the backing beam deflection budget. An example of a 3.9 m undulator supporting carriage mounted with 50-mm period length undulator magnet (U5) under a maximum magnetic loading of 5 metric tons at a minimum operating gap of 14 mm, is provided. Its mechanical features are first examined via 3D commercial finite element code ANSYS that concludes the backing beam deflection is influenced heavily by the rigidity of the undulator support frames. Examining the corresponding spectral performance shows that significantly diminishing the undulator spectral ...
Simulation of space charge compensation in a multibeamlet negative ion beam.
Sartori, E; Maceina, T J; Veltri, P; Cavenago, M; Serianni, G
2016-02-01
Ion beam space charge compensation occurs by cumulating in the beam potential well charges having opposite polarity, usually generated by collisional processes. In this paper we investigate the case of a H(-) ion beam drift, in a bi-dimensional approximation of the NIO1 (Negative Ion Optimization phase 1) negative ion source. H(-) beam ion transport and plasma formation are studied via particle-in-cell simulations. Differential cross sections are sampled to determine the velocity distribution of secondary particles generated by ionization of the residual gas (electrons and slow H2 (+) ions) or by stripping of the beam ions (electrons, H, and H(+)). The simulations include three beamlets of a horizontal section, so that multibeamlet space charge and secondary particle diffusion between separate generation regions are considered, and include a repeller grid biased at various potentials. Results show that after the beam space charge is effectively screened by the secondary plasma in about 3 μs (in agreement with theoretical expectations), a plasma grows across the beamlets with a characteristic time three times longer, and a slight overcompensation of the electric potential is verified as expected in the case of negative ions. PMID:26932089
Frequency-temperature compensated sapphire loaded cavity for compact hydrogen masers
International Nuclear Information System (INIS)
We report some theoretical and experimental results about a frequency-temperature compensated sapphire loaded cavity for compact hydrogen maser atomic clocks. Based on theoretical calculations, the frequency-temperature coefficients in the TE011 mode of a sapphire cavity associated with two small rings of SrTiO3 can be reduced. For instance, at 50 C, when the thickness of the SrTiO3 ring is 5 mm, the frequency-temperature coefficient can be reduced by about five times, and in the meantime, the quality factor can be kept at above 40 000 synchronously. A sapphire loaded cavity and eight small compensated chips of SrTiO3 were prepared and a combined cavity of sapphire with SrTiO3 chips was simulated by the finite element method and measured by experiments. The simulation and the related experimental results agree well. In addition, the frequency-temperature coefficients in two different configurations of eight SrTiO3 chips were also measured and compared. (authors)
Scattering-compensated cone beam x-ray luminescence computed tomography
Gao, Peng; Rong, Junyan; Pu, Huangsheng; Liu, Wenlei; Liao, Qimei; Lu, Hongbing
2016-04-01
X-ray luminescence computed tomography (XLCT) opens new possibilities to perform molecular imaging with x-ray. It is a dual modality imaging technique based on the principle that some nanophosphors can emit near-infrared (NIR) light when excited by x-rays. The x-ray scattering effect is a great issue in both CT and XLCT reconstruction. It has been shown that if the scattering effect compensated, the reconstruction average relative error can be reduced from 40% to 12% in the in the pencil beam XLCT. However, the scattering effect in the cone beam XLCT has not been proved. To verify and reduce the scattering effect, we proposed scattering-compensated cone beam x-ray luminescence computed tomography using an added leading to prevent the spare x-ray outside the irradiated phantom in order to decrease the scattering effect. Phantom experiments of two tubes filled with Y2O3:Eu3+ indicated that the proposed method could reduce the scattering by a degree of 30% and can reduce the location error from 1.8mm to 1.2mm. Hence, the proposed method was feasible to the general case and actual experiments and it is easy to implement.
An alternative approach to compensators design for photon beams used in radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Jurkovic, S. [University Hospital, Department of Radiotherapy, Physics Division, Kresimirova 42, 51000 Rijeka (Croatia); Zauhar, G. [School of Medicine, Department of Physics, Brace Branchetta 20, 51000 Rijeka (Croatia)], E-mail: gordz@medri.hr; Bistrovic, M. [Hospital for Tumors, Radiotherapy Department, Ilica 272, 10000 Zagreb (Croatia); Faj, D. [University Hospital, Department of Radiotherapy and Oncology, J. Huttlera 4, 31000 Osijek (Croatia); Kaliman, Z. [Faculty of Sciences and Arts, Department of Physics, Omladinska 14, 51000 Rijeka (Croatia); Smilovic Radojcic, D. [University Hospital, Department of Radiotherapy, Physics Division, Kresimirova 42, 51000 Rijeka (Croatia)
2007-09-21
The use of compensators in order to achieve desired dose distribution has a long history and is a well-established technique in radiation therapy planning. There are several different calculation methods for determining a compensator's thickness. An alternative method that is based on the Cunningham's modification of Clarkson's method to calculate scattered radiation in beams with an inhomogeneous cross-section is proposed. It is well known that the total dose distribution of radiotherapy photon beam consists of the contributions of the primary beam, attenuated by the tissue layer, and the scattered radiation generated by the primary radiation in single and multiple photon scatter events. The scattered component can be represented as a function of the primary radiation. The central point of our method is the numerical estimation of the primary distribution required to achieve the desired total distribution. Now using the calculated primary distribution, the shape of the modulator could be determined. In this way the contribution of the scattered component is validated in a more accurate way than using effective attenuation coefficients, which is a common practice. The method is verified in various clinical situations and compared with the standard method. The accuracy, although dependent on geometry, was improved by at least 2%. With more complex geometries there is an even higher gain in accuracy with our method when compared to the standard method.
Image-based motion compensation for high-resolution extremities cone-beam CT
Sisniega, A.; Stayman, J. W.; Cao, Q.; Yorkston, J.; Siewerdsen, J. H.; Zbijewski, W.
2016-03-01
Purpose: Cone-beam CT (CBCT) of the extremities provides high spatial resolution, but its quantitative accuracy may be challenged by involuntary sub-mm patient motion that cannot be eliminated with simple means of external immobilization. We investigate a two-step iterative motion compensation based on a multi-component metric of image sharpness. Methods: Motion is considered with respect to locally rigid motion within a particular region of interest, and the method supports application to multiple locally rigid regions. Motion is estimated by maximizing a cost function with three components: a gradient metric encouraging image sharpness, an entropy term that favors high contrast and penalizes streaks, and a penalty term encouraging smooth motion. Motion compensation involved initial coarse estimation of gross motion followed by estimation of fine-scale displacements using high resolution reconstructions. The method was evaluated in simulations with synthetic motion (1-4 mm) applied to a wrist volume obtained on a CMOS-based CBCT testbench. Structural similarity index (SSIM) quantified the agreement between motion-compensated and static data. The algorithm was also tested on a motion contaminated patient scan from dedicated extremities CBCT. Results: Excellent correction was achieved for the investigated range of displacements, indicated by good visual agreement with the static data. 10-15% improvement in SSIM was attained for 2-4 mm motions. The compensation was robust against increasing motion (4% decrease in SSIM across the investigated range, compared to 14% with no compensation). Consistent performance was achieved across a range of noise levels. Significant mitigation of artifacts was shown in patient data. Conclusion: The results indicate feasibility of image-based motion correction in extremities CBCT without the need for a priori motion models, external trackers, or fiducials.
Experimental Dynamic Analysis of Nonlinear Beams under Moving Loads
Directory of Open Access Journals (Sweden)
A. Bellino
2012-01-01
Full Text Available It is well known that nonlinear systems, as well as linear time-varying systems, are characterized by non-stationary response signals. In this sense, they both show natural frequencies that are not constant over time; this variation has however different origins: for a time-varying system the mass, and possibly the stiffness distributions, are changing over time, while for a nonlinear system the natural frequencies are amplitude-dependent. An interesting case of time-varying system occurs when analyzing the transit of a train over a railway bridge, easily simulated by the crossing of a moving load over a beam. In this case, the presence of a nonlinearity in the beam behaviour can cause a significant alteration of the modal parameters extracted from the linearized model, such that the contributions of the two effects are no more distinguishable.
New diagnostic technique for Zeeman-compensated atomic beam slowing: technique and results
Molenaar, P.A.; Van Der Straten, P.; Heideman, H.G.M.; Metcalf, H.
2001-01-01
We have developed a new diagnostic tool for the study of Zeeman-compensated slowing of an alkali atomic beam. Our time-of-flight technique measures the longitudinal veloc- ity distribution of the slowed atoms with a resolution below the Doppler limit of 30 cm/s. Furthermore, it can map the position and velocity distribution of atoms in either ground hyperfine level inside the solenoid without any devices inside the solenoid. The technique reveals the optical pumping ef- fects, and shows in de...
Exact fan-beam compensated reconstruction formula for time-dependent affine deformations
International Nuclear Information System (INIS)
This work is dedicated to the reduction of reconstruction artefacts due to motions occurring during the acquisition of computerized tomographic projections. This problem has to be solved when imaging moving organs such as the lungs or the heart. The proposed method belongs to the class of motion compensated algorithms, where the model of motion is included in the reconstruction formula. The questions that have to be answered in this approach are: first what conditions the deformation has to verify to allow the reconstruction of the object from the projections acquired sequentially during the deformation? and second how can we reconstruct the object in that case? Here we solve these questions in the particular case of general time-dependent affine deformations. We treat the problem of admissibility conditions on the deformation in the parallel-beam and in the fan-beam cases. Then we propose for both geometries exact reconstruction methods based on re-binning or sequential FBP formulae. (author)
Springback Prediction and Compensation for a High Strength Steel Side Impact Beam
Dutton, Trevor; Edwards, Richard; Blowey, Andrew
2005-08-01
Prediction of formability for sheet metal pressings has advanced to a high state of confidence in recent years. The major challenge is now to predict springback and, moreover, to assist in the design of tooling to correctly compensate for springback. This is particularly the case for materials now being routinely considered for automotive production, such as aluminium and ultra high strength steels, which are prone to greater degrees of springback than traditional mild steels. This paper presents a case study based on the tool design for an ultra high strength steel side impact beam. The forming and springback simulations, carried out using eta/DYNAFORM (based on the LS-DYNA solver), are reported and compared to measurements from the prototype panels. The analysis parameters used in the simulation are presented, and the sensitivity of the results to variation in physical properties is also reviewed. The process of compensating the tools based on the analysis prediction is described; finally, an automated springback compensation method is also applied and the results compared with the final tool design.
Investigation of ion beam space charge compensation with a 4-grid analyzer
Energy Technology Data Exchange (ETDEWEB)
Ullmann, C., E-mail: c.ullmann@gsi.de; Adonin, A.; Berezov, R.; Fils, J.; Hollinger, R.; Kester, O. [GSI, Darmstadt (Germany); Chauvin, N.; Delferrière, O.; Senée, F.; Tuske, O. [CEA, Saclay (France)
2016-02-15
Experiments to investigate the space charge compensation of pulsed high-current heavy ion beams are performed at the GSI ion source text benches with a 4-grid analyzer provided by CEA/Saclay. The technical design of the 4-grid analyzer is revised to verify its functionality for measurements at pulsed high-current heavy ion beams. The experimental investigation of space charge compensation processes is needed to increase the performance and quality of current and future accelerator facilities. Measurements are performed directly downstream a triode extraction system mounted to a multi-cusp ion source at a high-current test bench as well as downstream the post-acceleration system of the high-current test injector (HOSTI) with ion energies up to 120 keV/u for helium and argon. At HOSTI, a cold or hot reflex discharge ion source is used to change the conditions for the measurements. The measurements were performed with helium, argon, and xenon and are presented. Results from measurements with single aperture extraction systems are shown.
Investigation of ion beam space charge compensation with a 4-grid analyzer
Ullmann, C.; Adonin, A.; Berezov, R.; Chauvin, N.; Delferrière, O.; Fils, J.; Hollinger, R.; Kester, O.; Senée, F.; Tuske, O.
2016-02-01
Experiments to investigate the space charge compensation of pulsed high-current heavy ion beams are performed at the GSI ion source text benches with a 4-grid analyzer provided by CEA/Saclay. The technical design of the 4-grid analyzer is revised to verify its functionality for measurements at pulsed high-current heavy ion beams. The experimental investigation of space charge compensation processes is needed to increase the performance and quality of current and future accelerator facilities. Measurements are performed directly downstream a triode extraction system mounted to a multi-cusp ion source at a high-current test bench as well as downstream the post-acceleration system of the high-current test injector (HOSTI) with ion energies up to 120 keV/u for helium and argon. At HOSTI, a cold or hot reflex discharge ion source is used to change the conditions for the measurements. The measurements were performed with helium, argon, and xenon and are presented. Results from measurements with single aperture extraction systems are shown.
Investigation of ion beam space charge compensation with a 4-grid analyzer
International Nuclear Information System (INIS)
Experiments to investigate the space charge compensation of pulsed high-current heavy ion beams are performed at the GSI ion source text benches with a 4-grid analyzer provided by CEA/Saclay. The technical design of the 4-grid analyzer is revised to verify its functionality for measurements at pulsed high-current heavy ion beams. The experimental investigation of space charge compensation processes is needed to increase the performance and quality of current and future accelerator facilities. Measurements are performed directly downstream a triode extraction system mounted to a multi-cusp ion source at a high-current test bench as well as downstream the post-acceleration system of the high-current test injector (HOSTI) with ion energies up to 120 keV/u for helium and argon. At HOSTI, a cold or hot reflex discharge ion source is used to change the conditions for the measurements. The measurements were performed with helium, argon, and xenon and are presented. Results from measurements with single aperture extraction systems are shown
Dynamic Responses of Supported Beams with Intermediate Supports Under Moving Loads
Directory of Open Access Journals (Sweden)
Biaobiao Zhang
2012-01-01
Full Text Available In this paper, a new beam shape function configuration method for determining transient responses of a finite Euler-Bernoulli beam with two intermediate supports excited by moving pressure wave loads is developed. To clarify this method, this beam structure is excited by the moving sinusoidal loads as an example. Transient responses of this beam structure are investigated and verified by the traditional finite element method. This method can be used to solve transient response problems of moving pressure loads exciting the beam structure with intermediate support. Actually it can be extended to solve other complicated beam structure problems.
Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong
2016-05-01
Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this
Vibration Analysis of a Simply Supported Beam Traversed by Uniform Distributed Moving Load
Institute of Scientific and Technical Information of China (English)
Yu YANG; Nian-guan TENG; Yian-feng TENG
2004-01-01
Considering the engineering background of some transportation system like maglev, vertical vibration of the simply supported beam is investigated. The length of the vehicle is assumed to be longer than the beam span. The model of moving distributed load with constant speed is established .The beam can be taken as Euler-Bernoulli beam model and the right side of the control equation is simplified by using a moving status function. Duhamel integral and mode superposition method is used to solve the dynamic behavior of the beam. In this aspect deflection and acceleration are included. The results of different parameters such as the span of beam, velocity of load and ratio vehicle-Beam masses are compared. All results show that the dynamic response of the beam is tied up with these factors: the frequency of the beam, the moving frequency of the load and the ratio of vehicle-beam mass.
Diethold, Christian; Hilbrunner, Falko
2012-07-01
This paper discusses the force measurement of small forces in combination with high dead loads. The measurement force acts perpendicular to gravity, while the dead load is orientated in the direction of gravity. Furthermore, the influence of the dead load on the metrological properties is described. The application is the flow rate measurement of conducting fluids by Lorentz force (Thess et al 2006 Phys. Rev. Lett. 96 164501). The aim is to measure forces with a resolution of FM = 10-6 N. The dead load is mainly due to the mass of the magnet system. It is of the order of magnitude of FG = 10 N. The force measurement system works with the principle of electromagnetic force compensation. The applied force is compensated by a Lorentz force induced by a current in a voice coil and a magnetic field of a permanent magnet. The current is proportional to the applied force.
International Nuclear Information System (INIS)
This paper discusses the force measurement of small forces in combination with high dead loads. The measurement force acts perpendicular to gravity, while the dead load is orientated in the direction of gravity. Furthermore, the influence of the dead load on the metrological properties is described. The application is the flow rate measurement of conducting fluids by Lorentz force (Thess et al 2006 Phys. Rev. Lett. 96 164501). The aim is to measure forces with a resolution of FM = 10−6 N. The dead load is mainly due to the mass of the magnet system. It is of the order of magnitude of FG = 10 N. The force measurement system works with the principle of electromagnetic force compensation. The applied force is compensated by a Lorentz force induced by a current in a voice coil and a magnetic field of a permanent magnet. The current is proportional to the applied force. (paper)
Simulation Study on the Emittance Compensation of Off-axis Emitted Beam in RF Photoinjector
Huang, Rui-Xuan; Jia, Qi-Ka; Papadopoulos, Christos; Sannibale, Fernando
2016-01-01
To make full use of photocathode material and improve its quantum efficiency lifetime, it can be necessary to operate laser away from the cathode center in photoinjectors. In RF guns, the off-axis emitted beam will see a time-dependent RF effect, which would generate a significant growth in transverse emittance. It has been demonstrated that such an emittance growth can be almost completely compensated by orienting the beam on a proper orbit in the downstream RF cavities along the injector. In this paper we analyze in detail the simulation techniques used in reference[1] and the issues associated with them. The optimization of photoinjector systems involving off-axis beams is a challenging problem. To solve this problem, one needs advanced simulation tools including both genetic algorithms and an efficient algorithm for 3D space charge. In this paper, we report on simulation studies where the two codes ASTRA and IMPACT-T are used jointly to overcome these challenges, in order to optimize a system designed to ...
Власенко, Руслан Володимирович; Бялобржеський, Олексій Володимирович
2016-01-01
Electricity quality improving is extremely relevant nowadays. With such industrial loads as induction motors, induction furnaces, welding machines, controlled or uncontrolled rectifiers, frequency converters and others reactive power, harmonics and unbalance are generated in power grid. Reactive power, higher harmonic currents and asymmetry loads influence the functioning of electric devices and electrical mains. An effective technical solution is the use of new compensating devices, that is ...
Experimental Study of RC Beams Strengthened with CFRP Sheets Under Sustaining Loads
Institute of Scientific and Technical Information of China (English)
WANG Wenwei; LI Guo
2006-01-01
Seven reinforced concrete (RC) beams strengthened in flexure using carbon fiber reinforced polymer (CFRP) sheets subjected to different sustaining loads were tested. The effects of initial load and load history on the ultimate strength of strengthened RC beams were examined by externally bonded CFRP sheets. The main experimental parameters included different levels of sustaining load at the time of strengthening, and load history. Experimental results show that sustaining load levels at the time of strengthening have important influences on the ultimate strength of strengthened RC beams. If the initial load is the same, the ultimate strength of RC beams strengthened with CFRP sheets is almost the same regardless of load history at the time of strengthening.
Ding, Lan; Zhu, Hong-Ping; Wu, Li
2016-07-01
The propagation and attenuation properties of waves in ordered and disordered periodic composite Timoshenko beams, which consider the effects of axial static load and structural damping, resting on elastic foundations are studied when the system is subjected to moving loads of constant amplitude with a constant velocity. The transfer matrix methodology is adopted to formulate the model in a reference coordinate system moving with the load. The localization factor is calculated to determine the wave velocity pass bands and stop bands. The interactions between the static axial load and moving load, structural damping and disorder on the bands are analyzed.
DEFF Research Database (Denmark)
Markou, Helen; Andersen, Peter Bjørn; Larsen, Gunner Chr.
2011-01-01
for the loading conditions of the individual turbines in the farm. The dynamic wake meandering model (DWM) is believed to capture the essential physics of the wake problem, and thus, both load and production aspects can be predicted, which is contrary to the traditional engineering wake prediction methods......-servo-elastic tool HAWC2, developed at Risø-DTU in Denmark, and their potential load reduction capabilities compared: (1) full-blade ‘individual-pitch controllers’ acting as wake compensators and (2) controllers using trailing-edge flaps. Information on the wake inflow conditions, induced by upstream turbines...... that typically focus on either load or power prediction. As a consequence, the wake affected inflow field generated by the DWM formulation opens for control strategies for the individual turbine. Two different control approaches for load reduction on the individual turbines are implemented in the multi-body aero...
Hu, Pengcheng; Mao, Shuai; Tan, Jiu-Bin
2015-11-01
A measurement system with three degrees of freedom (3 DOF) that compensates for errors caused by incident beam drift is proposed. The system's measurement model (i.e. its mathematical foundation) is analyzed, and a measurement module (i.e. the designed orientation measurement unit) is developed and adopted to measure simultaneously straightness errors and the incident beam direction; thus, the errors due to incident beam drift can be compensated. The experimental results show that the proposed system has a deviation of 1 μm in the range of 200 mm for distance measurements, and a deviation of 1.3 μm in the range of 2 mm for straightness error measurements.
Shear Behavior of Novel Prestressed Concrete Beam Subjected to Monotonic and Cyclic Loading
Institute of Scientific and Technical Information of China (English)
余芳; 姚大立; 贾金青; 吴锋
2014-01-01
Prestressed steel ultrahigh-strength reinforced concrete (PSURC) beam is a new type of prestressed con-crete beam, which not only has a considerable compressive strength attributed to the ultrahigh strength concrete, but also ensures a certain degree of ductility at failure due to the existence of structural steel. Five of these beams were monotonically tested until shear failure to investigate the static shear performance including the failure pattern, load-deflection behavior, shear capacity, shear crack width and shear ductility. The experimental results show that these beams have superior shear capacity, crack control ability and shear ductility. To study the shear performance under repeated overloading, seven PSURC beams were loaded in cyclic test simultaneously. The overall shear performance of cycled beams is similar to that of uncycled beams at low load level but different at high load level. The shear capac-ity and crack control ability of cycled beams at high load level are reduced, whereas the shear ductility is improved. In addition, the influences of variables including the degree of prestress, stirrup ratio and load level on the shear perform-ance of both uncycled and cycled beams were also discussed and compared, respectively.
Palmer, Dennis T.; Miller, Roger H.; Winick, Herman; Wang, Xi J.; Batchelor, Kenneth; Woodle, Martin H.; Ben-Zvi, Ilan
1995-09-01
A dedicated low energy (2 to 10 MeV) experimental beam line is now under construction at Brookhaven National Laboratory/Accelerator Test Facility (BNL/ATF) for photocathode RF gun testing and photoemission experiments. Microwave measurements of the 1.6 cell photocathode RF gun have been conducted along with beam dynamics simulations of the emittance compensated low energy beam. These simulations indicate that the 1.6 cell photocathode RF gun in combination with solenoidal emittance compensation will be capable of producing a high brightness beam with a normalization rms emittance of (epsilon) n,rms approximately equals 1 (pi) mm mrad. The longitudinal accelerating field Ez has been measured as a function of azimuthal angle in the full cell of the cold test model for the 1.6 cell BNL/SLAC/UCLA #3 S-band RF Gun using a needle rotation/frequency perturbation technique. These measurements were conducted before and after symmetrizing the full cell with a vacuum pump out port and an adjustable short. Two different waveguide to full cell coupling schemes were studied. Experimental and theoretical studies of the field balance versus mode separation were conducted. The dipole mode of the full cell using the (theta) - coupling scheme is an order of magnitude less severe before symmetrization than the Z- coupling scheme. The multi-pole contribution to the longitudinal field asymmetry are calculated using standard Fourier series techniques for both coupling schemes. The Panofsky- Wenzel theorem is used in estimating the transverse emittance due to the multipole components of Ez. Detailed beam dynamics simulations were performed for the 1.6 cell photocathode RF gun injector using a solenoidal emittance compensation technique. The design of the experimental line along with a proposed experimental program using the 1.6 cell photocathode RF gun developed by the BNL/SLAC/UCLA RF gun collaboration is presented. This experimental program includes measurements of beam loading caused
Inverse problem of elastica of a variable-arc-length beam subjected to a concentrated load
Institute of Scientific and Technical Information of China (English)
Xiaowei Zhang; Jialing Yang; Keren Wang
2005-01-01
An inverse problem of elastica of a variable-arclength beam subjected to a concentrated load is investigated.The beam is fixed at one end, and can slide freely over a hinge support at the other end. The inverse problem is to determine the value of the load when the deflection of the action point of the load is given. Based on the elasitca equations and the elliptic integrals, a set of nonlinear equations for the inverse problem are derived, and an analytical solution by means of iterations and Quasi-Newton method is presented. From the results, the relationship between the loads and deflections of the loading point is obtained.
Beam loading in a laser-plasma accelerator using a near-hollow plasma channel
Schroeder, Carl
2014-01-01
Beam loading in laser-plasma accelerators using a near-hollow plasma channel is examined in the linear wake regime. It is shown that, by properly shaping and phasing the witness particle beam, high-gradient acceleration can be achieved with high-efficiency, and without induced energy spread or emittance growth. Both electron and positron beams can be accelerated in this plasma channel geometry. Matched propagation of electron beams can be achieved by the focusing force provided by the chan...
Load history-based model for prestressed concrete beam damage evaluation
Institute of Scientific and Technical Information of China (English)
Yuan Jianli; Wang Yi; Qian Zhonghui
2007-01-01
The residual capability of a damaged structure to resist further load is essential in optimal seismic design and post-earthquake strengthening.An experimental study on the hysteretic characteristics of prestressed concrete frame beams under different loading histories was performed to explore the influence of load history on energy dissipation and failure characteristics of the member.Based on the test results,the failure of the beam is defined,and the relationship between the failure moment under cyclic load and from the skeleton curve is formulated.Finally,based on displacement and energy dissipation,a model for prestressed concrete beam damage-failure evaluation is developed.In this model,the effect of deformation level,cumulative dissipated energy,and loading history on prestressed concrete beam damage-failure is incorporated,thus it is applicable to stochastic earthquake forces.
Numerical analysis of prestressed reinforced concrete beam subjected to blast loading
International Nuclear Information System (INIS)
Highlights: • Numerical study of prestressed RC beam against blast loadings by using LS-DYNA. • Numerical model is calibrated with testing results available. • The prestress is pre-applied on the RC beam in an analytical approach. • Parametric studies on prestress, concrete compressive strength and blast load. • Blast resistance performance of prestressed beam is identified. - Abstract: Prestressing technique has been widely used in civilian and military constructions. The prestressed reinforced concrete (RC) structural components such as beams and columns usually outperform the non-prestressed RC components because prestressing not only increases the structural stiffness and load carrying capacity, but also has higher crack resistance than non-prestressed component. As a result, it usually leads to light structures. The investigation of non-prestressed RC components subjected to blast loadings has been reported in the literature. However, the study on the blast-resistant capacity of prestressed RC components is very limited. In this study, the dynamic response of a simply-supported prestressed RC beam with rectangular section under blast loadings is numerically investigated by using finite element codes LS-DYNA. The prestress is pre-applied on the RC beam in an analytical approach. The reliability of the numerical model is calibrated with testing results available in the literature. With the calibrated model, numerical simulations on four groups of prestressed RC beams to blast loadings are carried out to investigate the influences of prestressing level and concreted compressive strength on beam blast loading resistance capacity. The structural responses such as mid-span maximum deflection, residual deflection, cracking, stress of rebars and shear stress of concrete near the supports are extracted from the numerical results. The effectiveness of prestressing on blast-resistant capacity of RC beam is demonstrated through comparing the results with the
RC beam strengthened with pre-stressed CFP under the secondary load
Institute of Scientific and Technical Information of China (English)
LONG Bang-yun; YUAN Guang-lin; ZHU Dan-yu
2008-01-01
Feasibility of using pre-stressed carbon fiber plates to strengthen reinforced concrete beams was studied. Based on the characteristics of carbon fiber plates, we developed a pre-stress clamp and a device for applying the pre-stress. Contrast tests were conducted between ordinary carbon fiber plates and a pre-stressed carbon fiber plate and between secondary loaded carbon fiber plates and a concrete beam strengthened with a secondary loaded carbon fiber plate. On this basis, we analyzed the failure pattern,the width of cracks and their distribution, the cracking load, the yield load, the limit load and the relation between load and deflection. The results indicate that using pre-stressed carbon fiber plates to strengthen concrete beams is feasible and effective.
Research on crack width evolution of RC beams strengthened with CFL under cyclic loads
Zhao, Chen; Huang, Peiyan; Guo, Xinyan
2008-11-01
Using carbon fiber laminate (CFL) invented by our group, we take the lead in studying the fatigue behaviors of the beams strengthened with FRP under the cyclic loads. The maximum crack width of the RC beams strengthened with CFL conforms to the law of three-stages, and the main factors which affect the fatigue crack propagation behavior was analyzed. Theoretical analyses are performed for the evolvement rule of maximum crack width of the strengthened RC beams under constant amplitude and random fatigue loads. Then, a method for calculating the propagation rule of maximum flexural crack width under fatigue loads is proposed, based on the initial crack width under static loads and the coefficient of the strain of CFL. This method can be used not only for crack width determination under constant amplitude cyclic load but also the random fatigue load. Using the method, permissive fatigue life can be estimated.
Kanematsu, Nobuyuki; Ogata, Risa
2012-01-01
Purpose: Beam range control is the essence of radiotherapy with heavy charged particles. In conventional broad-beam delivery, fine range adjustment is achieved by insertion of range shifting and compensating materials. Ideally, such material should be water equivalent as well as that for dosimetry. In this study, we evaluated dosimetric water equivalency of four common plastics, HDPE, PMMA, PET, and POM, by uniformity of effective densities for carbon-ion-beam interactions. Methods: Using the Bethe formula for stopping, the Gottschalk formula for multiple scattering, and the Sihver formula for nuclear interactions, we calculated the effective densities of the plastics for these interactions. We tested HDPE, PMMA, and POM in carbon-ion-beam experiment and measured attenuations of carbon ions, which were compared with empirical linear-attenuation-model calculations. Results: The theoretical calculations resulted in reduced multiple scattering and increased nuclear interactions for HDPE compared to water, which ...
Directory of Open Access Journals (Sweden)
V.Ts. Gnuni
2016-03-01
Full Text Available The non-conservative stability problem of pressing beam when two support billeting symmetrical on arbitrarily distance from the end is considered. It is show the possibility statical form loss of stability. The critical loads are determined.
Ultimate load analysis of pretensioned inverted T-beams with circular web openings
Institute of Scientific and Technical Information of China (English)
Hock Tian CHENG; Bashar S. MOHAMMED; Kamal Nasharuddin MUSTAPHA
2009-01-01
The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts not only results in a more systematic layout of pipes and ducts, it also translates into substantial economic savings in the construction of a multi-storey building. In this paper, ultimate load analysis of statically loaded simply supported pretensioned inverted T-beams with circular web openings is presented. Major findings relevant to ultimate load analysis of pretensioned beams with circular web openings are summarized. An attempt has been made to answer the frequently asked questions related to ultimate load analysis on multiple circular web open-ings. It has been shown that the analysis method for pretensioned beams with multiple large circular web openings can be further simplified without sacrificing rationality.
Directory of Open Access Journals (Sweden)
Reza Sedaghati
2013-09-01
Full Text Available In this paper, the structure of Hybrid Power Flow Controller (HPFC is proposed in order to improve static voltage stability characteristics. HPFC forms a hybrid controller using IPFC series converters as a hybrid with existing parallel and passive compensator (SVC in power system. Utilization of hybrid structures makes it possible to use converters for improving performance of both old and existing compensators in power networks. In this study, the power injection model (PIM is used to model the hybrid power flow controller in Newton load flow. The aforementioned model is simulated in MATLAB software. The P-V curves of PQ buses of a typical system are evaluated by a continuous power flow (CPF method to analyses the effect of this controller on static voltage stability characteristics. Meanwhile, SVC as existing devices in the system and UPFC and IPFC as state-of-the-art compensator devices are compared with the proposed hybrid structure. The amount of active and reactive power loss and improvement of loading limit of the system are used as main parameters in our comparison.
Compensating microphonics in SRF cavities to ensure beam stability for future free electron lasers
Energy Technology Data Exchange (ETDEWEB)
Neumann, Axel
2008-07-21
In seeded High-Gain-Harmonic-Generation free electron lasers or energy recovery linear accelerators the requirements for the bunch-to-bunch timing and energy jitter of the beam are in the femtosecond and per mill regime. This implies the ability to control the cavity radiofrequency (RF) field to an accuracy of 0.02 in phase and up to 1.10{sup -4} in amplitude. For the planned BESSY-FEL it is envisaged to operate 144 superconducting 1.3 GHz cavities of the 2.3 GeV driver linac in continuous wave mode and at a low beam current. The cavity resonance comprises a very narrow bandwidth of the order of tens of Hertz. Such cavities have been characterized under accelerator like conditions in the HoBiCaT test facility. It was possible to measure the error sources affecting the field stability in continuous wave (CW) operation. Microphonics, the main error source for a mechanical detuning of the cavities, lead to an average fluctuation of the cavity resonance of 1-5 Hz rms. Furthermore, the static and dynamic Lorentz force detuning and the helium pressure dependance of the cavity resonance have been measured. Single cavity RF control and linac bunch-to-bunch longitudinal phase space modeling containing the measured properties showed, that it is advisable to find means to minimize the microphonics detuning by mechanical tuning. Thus, several fast tuning systems have been tested for CW operation. These tuners consist of a motor driven lever for slow and coarse tuning and a piezo that is integrated into the tuner support for fast and fine tuning. Regarding the analysis of the detuning spectrum an adaptive feedforward method based on the least-mean-square filter algorithm has been developed for fast cavity tuning. A detuning compensation between a factor of two and up to a factor of seven has been achieved. Modeling the complete system including the fast tuning scheme, showed that the requirements of the BESSY-FEL are attainable. (orig.)
Performance of composite I-beams under axial compression and bending load modes
Energy Technology Data Exchange (ETDEWEB)
Khalid, Y.A.; Ali, F.A.; Sahari, B.B.; Saad, E.M.A
2005-04-15
An experimental and finite-element analyses for glass/epoxy composite I-beams have been carried out. Four, six, eight and 10 layers of woven fabric glass/epoxy composite I-beams were fabricated by a hand lay-up (molding) process. Quasi-static axial crushing and bending loading modes were used for this investigation. The load-displacement response was obtained and the energy absorption values were calculated for all the composite I-beams. Three tests were done for each composite I-beams type and each loading case for the results conformation. The second part of this study includes the elastic behavior of composite I-beams of the same dimensions and materials using finite-element analysis. The woven fabric glass/epoxy composite I-beams mechanical properties have been obtained from tensile tests. Results from this investigation show that the load required and the specific energy absorption for composite I-beams under axial compression load were higher than those for three and four point bending. On the other hand, the loads required for composite I-beams under four point bending were higher than those for three point bending, while the specific energy absorption for composite I-beams under three point bending were higher than those for four point bending. The first crushing loads difference between the experimental and finite-element results fell in the 3.6-10.92% range for axial compression tests, while fell in the 1.44-12.99% and 4.94-22.0% range for three and four point bending, respectively.
Large deflection response of restrained steel beams under fire and explosion loads
Xi, Feng
2016-01-01
A numerical study on the response of steel beams to fire and explosion is presented in this paper. First, a unified computing model, which can be used to simulate the behaviour of beams under four loading scenarios that involve fire and explosion or impact, is constructed. The proposed technique allows complete transparency of the influence of the various parameters on the structural behaviour. Second, the effects of load level on critical temperature are analyzed for various static and explo...
Institute of Scientific and Technical Information of China (English)
Lu Sun; Feiquan Luo; Tung-Huei Chen
2005-01-01
Beam responses under an impact NDT load are studied using the Fourier and Laplace transforms. Numerical computation is performed for a parametric study of beam and load parameters. It is shown that under an impact load, the time duration for displacement to vanish is ten times longer than that for velocity and acceleration. The maximum response is achieved first in acceleration, followed by velocity, and finally displacement, all of which occur before the impact load is removed. At the moment that the impact load is removed from the beam, there is a discontinuity in the velocity and acceleration responses, but not in displacement response. The effect of K and ph on beam response is much less significant than that of EI and C, which have similar effect on beam response. As EI increases, peak values of displacement, velocity and acceleration response decrease. The effect of K on beam response only becomes appreciable after the impact load is removed.While the peak of displacement remain almost unchanged as K increases, the displacement response decays to zero faster for large K values than for small K values.
Beam heat load measurements in the cold bore superconductive undulator in ANKA
Casalbuoni, S; Hagelstein, M; Zimmermann, F; Rossmanith, Robert; Kostka, Barbara; Mashkina, Elena; Steffens, Erhard; Bernhard, Axel; Wollmann, Daniel; Baumbach, Tilo
2007-01-01
Measurements of the beam-induced heat load in the ANKA cold-bore superconductive undulator are summarized. The strength of the two dominating effects, resistive wall heating and heating by electron bombardment, depends on the beam parameters and the gap width.
DEFF Research Database (Denmark)
Hanhijärvi, A.; Galimard, P.; Hoffmeyer, Preben
1998-01-01
The paper is the second in a series which sums up the results of an extensive project to quantify the duration-of-load (DOL) effect on different sized timber beams in different climates. The paper deals with straight (unnotched) beams. The results of various DOL-tests of stepwise and constant ben...
Sauppe, Sebastian; Hahn, Andreas; Brehm, Marcus; Paysan, Pascal; Seghers, Dieter; Kachelrieß, Marc
2016-03-01
We propose an adapted method of our previously published five-dimensional (5D) motion compensation (MoCo) algorithm1, developed for micro-CT imaging of small animals, to provide for the first time motion artifact-free 5D cone-beam CT (CBCT) images from a conventional flat detector-based CBCT scan of clinical patients. Image quality of retrospectively respiratory- and cardiac-gated volumes from flat detector CBCT scans is deteriorated by severe sparse projection artifacts. These artifacts further complicate motion estimation, as it is required for MoCo image reconstruction. For high quality 5D CBCT images at the same x-ray dose and the same number of projections as todays 3D CBCT we developed a double MoCo approach based on motion vector fields (MVFs) for respiratory and cardiac motion. In a first step our already published four-dimensional (4D) artifact-specific cyclic motion-compensation (acMoCo) approach is applied to compensate for the respiratory patient motion. With this information a cyclic phase-gated deformable heart registration algorithm is applied to the respiratory motion-compensated 4D CBCT data, thus resulting in cardiac MVFs. We apply these MVFs on double-gated images and thereby respiratory and cardiac motion-compensated 5D CBCT images are obtained. Our 5D MoCo approach processing patient data acquired with the TrueBeam 4D CBCT system (Varian Medical Systems). Our double MoCo approach turned out to be very efficient and removed nearly all streak artifacts due to making use of 100% of the projection data for each reconstructed frame. The 5D MoCo patient data show fine details and no motion blurring, even in regions close to the heart where motion is fastest.
Cyclic loadings on steel and lightweight concrete composite beams
Valente, Isabel; Cruz, Paulo J. S.
2006-01-01
This communication describes the experimental cyclic tests performed on steel and high strength lightweight concrete composite beams, at Universidade do Minho, Portugal. The experimental study involves tests on simply supported beams, all with the same geometrical disposition, supports and materials. Headed studs are used to provide the connection between the steel profile and the lightweight concrete slab. The parameters in study are the stud disposition and the number and range of the...
A Technique for Temperature and Ultimate Load Calculations of Thin Targets in a Pulsed Electron Beam
DEFF Research Database (Denmark)
Hansen, Jørgen-Walther; Lundsager, Per
1979-01-01
A technique is presented for the calculation of transient temperature distributions and ultimate load of rotationally symmetric thin membranes with uniform lateral load and exposed to a pulsed electron beam from a linear accelerator. Heat transfer by conduction is considered the only transfer...... mechanism. The ultimate load is calculated on the basis of large plastic strain analysis. Analysis of one aluminum and one titanium membrane is shown....
Bajoria, Kamal M.; Kaduskar, Shreya S.
2016-04-01
In this paper the structural behavior of reinforced concrete (RC) beams with smart rebars under two point loading system has been numerically studied, using Finite Element Method. The material used in this study is Super-elastic Shape Memory Alloys (SE SMAs) which contains nickel and titanium. In this study, different quantities of steel and SMA rebars have been used for reinforcement and the behavior of these models under two point bending loading system is studied. A comparison of load carrying capacity for the model between steel reinforced concrete beam and the beam reinforced with S.M.A and steel are performed. The results show that RC beams reinforced with combination of shape memory alloy and steel show better performance.
Beam Halo on the LHC TCDQ Diluter System and Thermal Load on the Downstream Superconducting Magnets
Goddard, B; Presland, A; Redaelli, S; Robert-Démolaize, G; Sarchiapone, L; Weiler, T; Weterings, W
2006-01-01
The moveable single-jawed graphite TCDQ diluter must be positioned very close to the circulating LHC beam in order to prevent damage to downstream components in the event of an unsynchronised beam abort. A two-jawed graphite TCS.IR6 collimator forms part of the TCDQ system. The requirement to place the jaws close to the beam means that the system can intercept a substantial beam halo load. Initial investigations indicated a worryingly high heat load on the Q4 coils. This paper presents the updated load cases, shielding and simulation geometry, and the results of simulations of the energy deposition in the TCDQ system and in the downstream superconducting Q4 magnet. The implications for the operation of the LHC are discussed.
Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Ramesh, G.
2015-06-01
This work describes the experimental investigation on behaviour of reinforced GPC beams subjected to monotonic static loading. The overall dimensions of the GPC beams are 250 mm × 300 mm × 2200 mm. The effective span of beam is 1600 mm. The beams have been designed to be critical in shear as per IS:456 provisions. The specimens were produced from a mix incorporating fly ash and ground granulated blast furnace slag, which was designed for a compressive strength of 40 MPa at 28 days. The reinforced concrete specimens are subjected to curing at ambient temperature under wet burlap. The parameters being investigated include shear span to depth ratio (a/d = 1.5 and 2.0). Experiments are conducted on 12 GPC beams and four OPCC control beams. All the beams are tested using 2000 kN servo-controlled hydraulic actuator. This paper presents the results of experimental studies.
Directory of Open Access Journals (Sweden)
Semina Yuliya Anatol'evna
2015-09-01
Full Text Available The behavior of reinforced concrete elements under some types of cyclic loads is described in the paper. The main aim of the investigations is research of the stress-strain state and strength of the inclined sections of reinforced concrete beam elements in conditions of systemic impact of constructive factors and the factor of external influence. To spotlight the problem of cyclic loadings three series of tests were conducted by the author. Firstly, the analysis of the tests showed that especially cyclic alternating loading reduces the bearing capacity of reinforced concrete beams and their crack resistance by 20 % due to the fatigue of concrete and reinforcement. Thus the change of load sign creates serious changes of stress-strain state of reinforced concrete beam elements. Low cycle loads of constant sign effect the behavior of the constructions not so adversely. Secondly, based on the experimental data mathematical models of elements’ strength were obtained. These models allow evaluating the impact of each factor on the output parameter not only separately, but also in interaction with each other. Furthermore, the material spotlighted by the author describes stress-strain state of the investigated elements, cracking mechanism, changes of deflection values, the influence of mode cyclic loading during the tests. Since the data on the subject are useful and important to building practice, the ultimate aim of the tests will be working out for improvement of nonlinear calculation models of span reinforced concrete constructions taking into account the impact of these loads, and also there will be the development of engineering calculation techniques of their strength, crack resistance and deformability.
Strength and behavior in shear of reinforced concrete deep beams under dynamic loading conditions
International Nuclear Information System (INIS)
Highlights: ► Effects of wider range of loading rates on dynamic shear behavior of RC deep beams. ► Experimental investigation of RC deep beam with and without shear reinforcements. ► Verification of experimental results with truss model and FE simulation results. ► Empirical equations are proposed to predict the dynamic increase factor of maximum resistance. -- Abstract: Research on reinforced concrete (RC) deep beams has seen considerable headway over the past three decades; however, information on the dynamic shear strength and behavior of RC deep beams under varying rates of loads remains limited. This paper describes the experimental results of 24 RC deep beams with and without shear reinforcements under varying rates of concentrated loading. Results obtained serve as useful data on shear resistance, failure patterns and strain rates corresponding to varying loading rates. An analytical truss model approach proves its efficacy in predicting the dynamic shear resistance under varying loading rates. Furthermore, three-dimensional nonlinear finite element (FE) model is described and the simulation results are verified with the experimental results. A parametric study is then conducted to investigate the influence of longitudinal reinforcement ratio, transverse reinforcement ratio and shear span to effective depth ratio on shear behavior. Subsequently, two empirical equations were proposed by integrating the various parameters to assess the dynamic increase factor (DIF) of maximum resistance under varying rates of concentrated loading
Strength and behavior in shear of reinforced concrete deep beams under dynamic loading conditions
Energy Technology Data Exchange (ETDEWEB)
Adhikary, Satadru Das [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Li, Bing, E-mail: cbli@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Fujikake, Kazunori [Department of Civil and Environmental Engineering, National Defense Academy, Yokosuka 239 8686 (Japan)
2013-06-15
Highlights: ► Effects of wider range of loading rates on dynamic shear behavior of RC deep beams. ► Experimental investigation of RC deep beam with and without shear reinforcements. ► Verification of experimental results with truss model and FE simulation results. ► Empirical equations are proposed to predict the dynamic increase factor of maximum resistance. -- Abstract: Research on reinforced concrete (RC) deep beams has seen considerable headway over the past three decades; however, information on the dynamic shear strength and behavior of RC deep beams under varying rates of loads remains limited. This paper describes the experimental results of 24 RC deep beams with and without shear reinforcements under varying rates of concentrated loading. Results obtained serve as useful data on shear resistance, failure patterns and strain rates corresponding to varying loading rates. An analytical truss model approach proves its efficacy in predicting the dynamic shear resistance under varying loading rates. Furthermore, three-dimensional nonlinear finite element (FE) model is described and the simulation results are verified with the experimental results. A parametric study is then conducted to investigate the influence of longitudinal reinforcement ratio, transverse reinforcement ratio and shear span to effective depth ratio on shear behavior. Subsequently, two empirical equations were proposed by integrating the various parameters to assess the dynamic increase factor (DIF) of maximum resistance under varying rates of concentrated loading.
STEADY-STATE RESPONSE OF A TIMOSHENKO BEAM ON AN ELASTIC HALF-SPACE UNDER A MOVING LOAD
Institute of Scientific and Technical Information of China (English)
Chen Yunmin; Wang Changjing
2006-01-01
By introducing the equivalent stiffness of an elastic half-space interacting with a Timoshenko beam, the displacement solution of the beam resting on an elastic half-space subjected to a moving load is presented. Based on the relative relation of wave velocities of the half-space and the beam, four cases with the combination of different parameters of the half-space and the beam, the system of soft beam and hard half-space, the system of sub-soft beam and hard halfspace, the system of sub-hard beam and soft half-space, and the system of hard beam and soft half-space are considered. The critical velocities of the moving load are studied using dispersion curves. It is found that critical velocities of the moving load on the Timoshenko beam depend on the relative relation of wave velocities of the half-space and the beam. The Rayleigh wave velocity in the half-space is always a critical velocity and the response of the system will be infinite when the load velocity reaches it. For the system of soft beam and hard half-space, wave velocities of the beam are also critical velocities. Besides the shear wave velocity of the beam, there is an additional minimum critical velocity for the system of sub-soft beam and hard half-space. While for systems of (sub-) hard beams and soft half-space, wave velocities of the beam are no longer critical ones.Comparison with the Euler-Bernoulli beam shows that the critical velocities and response of the two types of beams are much different for the system of (sub-) soft beam and hard half-space but are similar to each other for the system of (sub-) hard beam and soft half space. The largest displacement of the beam is almost at the location of the load and the displacement along the beam is almost symmetrical if the load velocity is smaller than the minimum critical velocity (the shear wave velocity of the beam for the system of soft beam and hard half-space). The largest displacement of the beam shifts behind the load and the asymmetry
Birefringence compensation in single solid-state rods
International Nuclear Information System (INIS)
Various methods for compensating birefringence depolarization in solid-state rods are theoretically and experimentally analyzed and compared. Gaussian and flat top beam profiles are investigated. The efficiency in depolarization loss reduction using different techniques is discussed in terms of beam profile, rod fill factor, and thermal heat load. In Nd:yttrium-aluminum-garnet, the depolarization loss can be efficiently reduced below 5% with a compensating quarter-waveplate, up to 20 W heat load for a flat top beam and up to 70 W for a gaussian beam. (c) 2000 American Institute of Physics
Numerical prediction of wave impact loads on multiple rectangular beams
DEFF Research Database (Denmark)
Mayer, Stefan; Nielsen, Kristian Bendix; Hansen, E.A.
2005-01-01
Wave impact on one and two structural beams with rectangular cross section is simulated with a two-dimensional finite volume method, solving the unsteady Euler equations and employing a VOF-type method for the description of the free surface. Four different test series are carried out, each...
On the dynamic stability of shear deformable beams under a tensile load
Caddemi, S.; Caliò, I.; Cannizzaro, F.
2016-07-01
Loss of stability of beams in a linear static context due to the action of tensile loads has been disclosed only recently in the scientific literature. However, tensile instability in the dynamic regime has been only marginally covered. Several aspects concerning the role of shear deformation on the tensile dynamic instability on continuous and discontinuous beams are still to be addressed. It may appear as a paradox, but also for the case of the universally studied Timoshenko beam model, despite its old origin, frequency-axial load diagrams in the range of negative values of the load (i.e. tensile load) has never been brought to light. In this paper, for the first time, the influence of a conservative tensile axial loads on the dynamic behaviour of the Timoshenko model, according to the Haringx theory, is assessed. It is shown that, under increasing tensile loads, regions of positive/negative fundamental frequency variations can be distinguished. In addition, the beam undergoes eigen-mode changes, from symmetric to anti-symmetric shapes, until tensile instability of divergence type is reached. As a further original contribution on the subject, taking advantage of a new closed form solution, it is shown that the same peculiarities are recovered for an axially loaded Euler-Bernoulli vibrating beam with multiple elastic sliders. This latter model can be considered as the discrete counterpart of the Timoshenko beam-column in which the internal sliders concentrate the shear deformation that in the Timoshenko model is continuously distributed. Original aspects regarding the evolution of the vibration frequencies and the relevant mode shapes with the tensile load value are highlighted.
Experimental Study on Impact Load Resistance of RC Beam with Corroded Reinforcement
Directory of Open Access Journals (Sweden)
Kuwahara Isao
2016-01-01
Full Text Available In Japan, many concrete bridges along the coastline have suffered corrosion due to the chloride attack from seawater and airborne salt. Therefore, now, several researches on corroded RC structures have been ongoing around the world. Especially, as a basic research, many researchers have studied on the numerical and experimental method to evaluate static load resistant capacity of RC beams with corroded reinforcements. However, there has been almost no research to evaluate impact load resistant capacity. Of course, it is important that impact load resistant capacity is clarified, if the possibility of acting of impact load including in natural disaster on corroded RC structures is dealt with. With a background like this, this paper describes an experimental investigation of the structural behavior of corroded RC beams. To be precise, in this study, RC beams with corroded reinforcement by using electrolytic corrosion method were made, and both of static loading test and repeated impact test for those RC beams were conducted in order to clarify the static and impact load resistant capacity of them. As a result, we could get some findings. At first, through repeated impact tests (which has 1.0m/s impact velocity and a 100kg steel weight, the number of impacts to the failure of corroded RC beams were less than half of healthy RC beams. It was also found that fracture pattern was completely different due to some axial cracks by corrosion. In addition, even though the corrosion rate is same level, the impact load resistant capacity reduce greatly compared to the static load resistant capacity because of the existence and pattern of cracks due to corrosion.
Application of sinusoidal load-change operation in order to compensate daily power demand variations
International Nuclear Information System (INIS)
In order to balance the daily variations of electric power demand a method for choosing optimal load management of nuclear power plants with PWR type reactors is presented. It is based on an approximate harmonic analysis of the daily load distribution
Flexural models of reinforced concrete beams under blast load
Stochino, Flavio
2013-01-01
Nowadays, the issue of structural safety under blast loading has become a dramatic problem. The tragic news of the terrorist attacks of recent years (9/11/2001, New York; 7/7/2005, London; 7/23/2005, Sharm El Sheik; 1/24/2011, Moscow; etc), raise important, urgent questions regarding the real safety and reliability of our buildings. Extreme loads such as impacts, explosions, etc., can occur in everyday life with unexpectedly high frequency. Actually, the problem of terrorist attacks, so...
Vasilyan, Suren; Rivero, Michel; Schleichert, Jan; Halbedel, Bernd; Fröhlich, Thomas
2016-04-01
In this paper, we present an application for realizing high-precision horizontally directed force measurements in the order of several tens of nN in combination with high dead loads of about 10 N. The set-up is developed on the basis of two identical state-of-the-art electromagnetic force compensation (EMFC) high precision balances. The measurement resolution of horizontally directed single-axis quasi-dynamic forces is 20 nN over the working range of ±100 μN. The set-up operates in two different measurement modes: in the open-loop mode the mechanical deflection of the proportional lever is an indication of the acting force, whereas in the closed-loop mode it is the applied electric current to the coil inside the EMFC balance that compensates deflection of the lever to the offset zero position. The estimated loading frequency (cutoff frequency) of the set-up in the open-loop mode is about 0.18 Hz, in the closed-loop mode it is 0.7 Hz. One of the practical applications that the set-up is suitable for is the flow rate measurements of low electrically conducting electrolytes by applying the contactless technique of Lorentz force velocimetry. Based on a previously developed set-up which uses a single EMFC balance, experimental, theoretical and numerical analyses of the thermo-mechanical properties of the supporting structure are presented.
Institute of Scientific and Technical Information of China (English)
顾文娟; 刘涛; 朱战霞; 孙力
2013-01-01
Through the servo loading system and the position synchronization afterburner compensate for load analysis,the proportion of a position to follow the force compensation loading system,and its MATLAB / SIMULINK modeling and simulation are presented.Finally,the position proportional follow the force compensating loading system simulation results,the results indicate that the system can effectively improve the system band.%通过对力伺服加载系统和位置同步加力补偿加载系统的分析,提出了一种位置比例跟随力补偿加载系统；并对其进行MATLAB/SIMULINK建模仿真.最后,对位置比例跟随力补偿加载系统的仿真结果进行了分析,结果说明该系统能够有效提高系统频带.
International Nuclear Information System (INIS)
This study introduces a new CFRC-strengthened RC beam model which can both strengthen and monitor the large-scale RC element used in concrete infrastructures. An experiment of testing four-point bending beams is proceeded in order to analyze mechanical behavior and electrical property of the designed beam under monotonic loading as well as the relationship between electrical property and fatigue damage under cyclic flexural loading. The analytical results indicate that this innovative CFRC-strengthened beam has better flexural performance due to the improved cracking resistance capacity of the CFRC layer. Besides, the change in electrical resistance of the beam is detected under monotonic loading. It is found that the thicker the CFRC layer, the larger the electrical resistance increases, and while electrical resistance irreversibly increases as load cycling progresses, the greater the stress amplitude, the greater the fatigue damage, and the larger the residual resistance increases. Based on this discovery, a new technique to monitor the damage of the designed CFRC-strengthened RC beam is produced by means of resistance measurement
Bending vibration of axially loaded Timoshenko beams with locally distributed Kelvin-Voigt damping
Chen, Wei-Ren
2011-06-01
Utilizing the Timoshenko beam theory and applying Hamilton's principle, the bending vibration equations of an axially loaded beam with locally distributed internal damping of the Kelvin-Voigt type are established. The partial differential equations of motion are then discretized into linear second-order ordinary differential equations based on a finite element method. A quadratic eigenvalue problem of a damped system is formed to determine the eigenfrequencies of the damped beams. The effects of the internal damping, sizes and locations of damped segment, axial load and restraint types on the damping and oscillating parts of the damped natural frequency are investigated. It is believed that the present study is valuable for better understanding the influence of various parameters of the damped beam on its vibration characteristics.
An exact dynamic stiffness matrix for axially loaded double-beam systems
Indian Academy of Sciences (India)
Li Xiaobin; Xu Shuangxi; Wu Weiguo; Li Jun
2014-06-01
An exact dynamic stiffness method is presented in this paper to determine the natural frequencies and mode shapes of the axially loaded double-beam systems,which consist of two homogeneous and prismatic beams with a distributed spring in parallel between them.The effects of the axial force, shear deformation and rotary inertia are considered, as shown in the theoretical formulation. The dynamic stiffness influence coefficients are formulated from the governing differential equations of the axially loaded double-beam system in free vibration by using the Laplace transform method. An example is given to demonstrate the effectiveness of this method, in which ten boundary conditions are investigated and the effect of the axial force on the natural frequencies and mode shapes of the double-beam system are further discussed.
A method for compensating bellows pressure loads while accommodating thermal deformations
International Nuclear Information System (INIS)
Many metal bellows are used on storage ring vacuum chambers. They allow the ring to accomodate deformations associated with alignment, mechanical assembly and thermal expansion. The NSLS has two such electron storage rings, the VUV ring and the X-Ray ring. Both rings utilize a number of welded metal bellows within the ring and at every beam port
Eigenvalues of an axially loaded cantilever beam with an eccentric end rigid body
Lajimi, S Amir Mousavi
2014-01-01
An analytical form of the characteristic equation for a vertically mounted cantilever beam with an end rigid body is obtained and solved for the eigenvalues of the structure. The effect of the weight of the structure is taken into consideration by estimating the load as a function of the length of the beam. The mass, rotary inertia and eccentricity of the end rigid body are demonstrated to considerably affect the eigenvalues of the structure.
Fangping Liu; Jianting Zhou
2016-01-01
Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equation...
Large deflections of a cantilever beam under arbitrarily directed tip load
Mccomb, H. E., Jr.
1985-01-01
The nonlinear beam equation was integrated numerically in a direct fashion to obtain results for large deflections of cantilevers under tip loads of arbitrary direction. A short BASIC computer program for performing this integration is presented. Results for selected load cases are presented. The numerical process is performed rapidly on a modern microcomputer, and comparisons with results from closed form solutions show that the process is accurate.
Analysis of DESY-Flash LLRF Measurements for the ILC Heavy Beam Loading Test
Energy Technology Data Exchange (ETDEWEB)
Cancelo, Gustavo; Chase, Brian; Davidsaver, Michael; /Fermilab; Carwardine, J.; /Argonne; Simrock, Stefan; Ayvazyan, Valeri; Grecki, Mariusz; /DESY; Matsumoto, Toshihiro; Michizono, Shinichiro; /KEK, Tsukuba
2009-06-01
In September 2008 the DESY-FLASH accelerator was run with up to 550, 3 nano-coulomb bunches at 5 Hz repetition rate. This test is part of a longer-term study aimed at validating ILC parameters by operation as close as possible to ILC beam currents and RF gradients. The present paper reports on the analysis that has been done in order to understand the RF control system performance during this test. Actual klystron power requirements and beam stability are evaluated with heavy beam loading conditions. Results include suggested improvements for upcoming tests in 2009.
A cyclic loading model for beam-to-column web connection
Institute of Scientific and Technical Information of China (English)
LIU Hong-bo; XIE li-li; SHAO Yong-song
2008-01-01
A finite element analysis of the beam-to-column web connection with H-shaped columns was performed using the ANSYS computer program.Based on the finite element analysis and theoretical analysis,a simplified model was developed to describe the cyclic loading behavior of beam-to-columns web connection in steel moment resisting frames,considering both bending and shear deformation modes of the beam flange plate.Several issues appearing to merit further researches were identified in the process of developing this model,such as the effect of beam flange plate on beam-to-column web connection stiffness and strength.A reasonable agreement was achieved between model predictions and finite element data,which verified the feasibihty of the proposed model.
Institute of Scientific and Technical Information of China (English)
Changguo Wang; Huifeng Tan; Xingwen Du
2009-01-01
This paper extends Le van's work to the case of nonlinear problem and the complicated configuration. The wrinkling stress distribution and the pressure effects are also included in our analysis. Pseudo-beam method is presented based on the inflatable beam theory to model the inflatable structures as a set of inflatable beam elements with a pre-stressed state. In this method, the discretized nonlinear equations are given based upon the virtual work principle with a 3-node Timoshenko's beam model. Finite element simulation is performed by using a 3-node BEAM189 element incorporating ANSYS nonlinear program. The pressure effect is equivalent included in our method by modifying beam element cross-section parameters related to pressure. A benchmark example, the bending case of an inflatable cantilever beam, is performed to verify the accuracy of our pro-posed method. The comparisons reveal that the numerical results obtained with our method are close to open published analytical and membrane finite element results. The method is then used to evaluate the whole buckling and the load-carrying characteristics of an inflatable support frame subjected to a compression force. The wrinkling stress and region characteristics are also shown in the end. This method gives better convergence characteristics, and requires much less computation time. It is very effective to deal with the whole load-carrying ability analytical problems for large scale inflatable structures with complex configuration.
PREDICTION OF FATIGUE LIVES OF RC BEAMS STRENGTHENED WITH CFL UNDER RANDOM LOADING
Institute of Scientific and Technical Information of China (English)
Rongwei Lin; Peiyan Huang; Chen Zhao; Xinyan Guo; Xiaohong Zheng
2008-01-01
The investigation on fatigue lives of reinforced concrete (RC) structures strength ened with fiber laminate under random loading is important for the repairing or the strengthening of bridges and the safety of the traffic.In this paper,two methods are developed for predicting the fatigue lives of RC structures strengthened with carbon fiber laminate (CFL) under random loading based on a residual life and a residual strength model.To discuss the efficiency of the model,12 RC beams strengthened with CFL are tested under random loading by the MTS810 testing system.The predicted residual strength approximately agrees with test results.
Predicting the behaviour of a wide sandwich beam under pressure loading
Davies, P.; Bigourdan, B.; Chaudot, P.; Choqueuse, D.; Ferreira, A.; Karjalainen, J.P.; Hildebrand, M.; Mustakangas, M.; Gaarder, R.; Carli, F.; Straalen, IJ.J. van; Sargent, J.P.; Adams, R.D.; Broughton, J.; Beevers, A.
2000-01-01
This paper presents results from analytical and finite elenent modelling of the response of a wide foam core sandwich beam to uniform pressure loading. New tests have been performed using an image analysis system which allows core shear strain mapping. Predicted panel displacenpnts and strains are c
Large deflection response of restrained steel beams under fire and explosion loads.
Xi, Feng
2016-01-01
A numerical study on the response of steel beams to fire and explosion is presented in this paper. First, a unified computing model, which can be used to simulate the behaviour of beams under four loading scenarios that involve fire and explosion or impact, is constructed. The proposed technique allows complete transparency of the influence of the various parameters on the structural behaviour. Second, the effects of load level on critical temperature are analyzed for various static and explosion load ratios. Two cases of explosion and fire loading sequences are compared, it is shown that the critical temperature of the beam subjected to fire followed by an explosion is lower than that of the beam subjected to an explosion followed by fire. The influence of temperature on the p-i diagram is investigated, an iso-damage surface is introduced to distinguish safe and unsafe regions. Third, the limiting temperature criteria are further examined. That is, the first and second limiting temperatures can be determined when the dimensional catenary force is equal to zero or to one, which corresponds to the bending or stretching plastic hinge, respectively. PMID:27386235
Development of educational software for beam loading analysis using pen-based user interfaces
Directory of Open Access Journals (Sweden)
Yong S. Suh
2014-01-01
Full Text Available Most engineering software tools use typical menu-based user interfaces, and they may not be suitable for learning tools because the solution processes are hidden and students can only see the results. An educational tool for simple beam analyses is developed using a pen-based user interface with a computer so students can write and sketch by hand. The geometry of beam sections is sketched, and a shape matching technique is used to recognize the sketch. Various beam loads are added by sketching gestures or writing singularity functions. Students sketch the distributions of the loadings by sketching the graphs, and they are automatically checked and the system provides aids in grading the graphs. Students receive interactive graphical feedback for better learning experiences while they are working on solving the problems.
Neutron spectra at two beam ports of a TRIGA Mark III reactor loaded with HEU fuel
International Nuclear Information System (INIS)
The neutron spectra have been measured in two beam ports, one radial and another tangential, of the TRIGA Mark III nuclear reactor from the National Institute of Nuclear Research in Mexico. Measurements were carried out with the reactor core loaded with high enriched uranium fuel. Two reactor powers, 5 and 10 W, were used during neutron spectra measurements using a Bonner sphere spectrometer with a 6LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter high-density polyethylene spheres. The neutron spectra were unfolded using the NSDUAZ unfolding code. For each spectrum total flux, mean energy and ambient dose equivalent were determined. Measured spectra show fission, epithermal and thermal neutrons, being harder in the radial beam port. - Highlights: • Neutron spectra of a TRIGA reactor were measured. • The reactor core is loaded with HEU. • The spectra were measured at two reactor beam ports. • Measurements were carried out at 5 and 10 W
Directory of Open Access Journals (Sweden)
Thamer Hanna
2013-04-01
Full Text Available This paper investigates the effect of steel and polypropylene fibers on static behavior of simply supported deep beams of normal concrete strength under patch loading. Also the paper studied the effect of web opening and its positions on shear capacity and mode of failures for steel fiber concrete deep beams under the same conditions of loading and strength. Sixteen beams of (1000*300*100mm, eighteen cubes (150*150*150mm and thirty cylinders (150*300mm in dimensions were cast with different fiber volume content (0, 0.4, 0.64 and 0.89% as additives. Shear capacity, mode of failure and three of mechanical strengths were tested. After testing, the results indicate that shear capacity increases with increasing volume of steel fiber content with change on mode of failure while midspan displacement decreases.
Extrinsic Influence of Environment-Induced Degradation on Load Carrying Capacity of Steel Beams
Gowda, Sunil; Patnaik, A.; Payer, J.; Srivatsan, T. S.
2015-11-01
In this paper, the results of a study aimed at evaluating the strength of wide-flanged beams subjected to corrosion-induced damage, modeled using a standard finite element program (ABAQUS) is presented and discussed. Typical beams in consideration were subjected to different cases of corrosion-induced damage, such as non-uniform and varying degree of material loss that simulates pitting corrosion. Many variables, such as (a) shape of pitting damage, (b) location of pits along the length of the beam, (c) number of pits, and (d) depth of pits, were considered to facilitate a better understanding of the load carrying capacity of steel I-beams having damage quite similar to pitting damage to the web. The results are compared with an "as-new" beam for purpose of evaluation of the reduction in strength due to environment-induced deterioration. A "corrosion strength reduction factor (CSRF)" is introduced to help identify the reduction in load carrying capacity as a consequence of both height and depth of the damage due to corrosion. The results are presented in charts for purpose of practical beam design.
Zhu, Fan; Tan, Xinran; Tan, Jiubin; Fan, Zhigang
2016-08-01
An autocollimation (AC) setup with ultra-high resolution and stability for micro-angle measurement is presented. The telephoto objective, which is characterized in long focal length at a compact structure size, and the optical enlargement unit, which can magnify the image displacement to improve its measurement resolution and accuracy, are used to obtain an ultra-high measurement resolution of the AC. The common-path beam drift compensation is used to suppress the drift of measurement results, which is evident in the high-resolution AC, thus to obtain a high measurement stability. Experimental results indicate that an effective resolution of better than 0.0005 arc sec (2.42 nrad) over a measurement range of ±30 arc sec and a 2-h stability of 0.0061 arc sec (29.57 nrad) can be achieved. PMID:27587181
Gamp, A
2011-01-01
We begin by giving a description of the rf generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, rf feedback, and feed-forward are described. Examples of digital rf phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.
SDOF models for reinforced concrete beams under impulsive loads accounting for strain rate effects
Energy Technology Data Exchange (ETDEWEB)
Stochino, F., E-mail: fstochino@unica.it [Department of Civil and Environmental Engineering and Architecture, University of Cagliari, Via Marengo 2, 09123 Cagliari (Italy); Carta, G., E-mail: giorgio_carta@unica.it [Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, 09123 Cagliari (Italy)
2014-09-15
Highlights: • Flexural failure of reinforced concrete beams under blast and impact loads is studied. • Two single degree of freedom models are formulated to predict the beam response. • Strain rate effects are taken into account for both models. • The theoretical response obtained from each model is compared with experimental data. • The two models give a good estimation of the maximum deflection at collapse. - Abstract: In this paper, reinforced concrete beams subjected to blast and impact loads are examined. Two single degree of freedom models are proposed to predict the response of the beam. The first model (denoted as “energy model”) is developed from the law of energy balance and assumes that the deformed shape of the beam is represented by its first vibration mode. In the second model (named “dynamic model”), the dynamic behavior of the beam is simulated by a spring-mass oscillator. In both formulations, the strain rate dependencies of the constitutive properties of the beams are considered by varying the parameters of the models at each time step of the computation according to the values of the strain rates of the materials (i.e. concrete and reinforcing steels). The efficiency of each model is evaluated by comparing the theoretical results with experimental data found in literature. The comparison shows that the energy model gives a good estimation of the maximum deflection of the beam at collapse, defined as the attainment of the ultimate strain in concrete. On the other hand, the dynamic model generally provides a smaller value of the maximum displacement. However, both approaches yield reliable results, even though they are based on some approximations. Being also very simple to implement, they may serve as an useful tool in practical applications.
Comparative study of beam losses and heat loads reduction methods in MITICA beam source
Energy Technology Data Exchange (ETDEWEB)
Sartori, E., E-mail: emanuele.sartori@igi.cnr.it; Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Veltri, P. [Consorzio RFX, Euratom-ENEA association, C.so Stati Uniti 4, 35127 Padova (Italy); Sonato, P. [Consorzio RFX, Euratom-ENEA association, C.so Stati Uniti 4, 35127 Padova (Italy); Dipartimento di Ingegneria Elettrica, Padova University, Via Gradenigo 6/a, 35131 Padova (Italy)
2014-02-15
In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.
A hybrid approach to analyse a beam-soil structure under a moving random load
Si, L. T.; Zhao, Y.; Zhang, Y. H.; Kennedy, D.
2016-11-01
To study the stochastic response of a beam-soil structure under a moving random load, a hybrid approach based on the pseudo-excitation method and the wavelet method is proposed. Using the pseudo-excitation method, the non-stationary random vibration analysis is transformed into a conventional moving harmonic load problem. Analytical solutions of the power spectral density and standard deviation of vertical displacement are derived in an integral form. However, the integrand is singular and highly oscillatory, and the computational time is an important consideration because a large number of frequency points must be computed. To calculate the response accurately and efficiently, a wavelet approach is introduced. Numerical results show that the frequency band which brings the most significant response is dependent on the load velocity. The hybrid method provides a useful tool to estimate the ground vibration caused by traffic loads.
Multi-axial load application and DIC measurement of advanced composite beam deformation behavior
Directory of Open Access Journals (Sweden)
Berggreen C.
2010-06-01
Full Text Available For the validation of a new beam element formulation, a wide set of experimental data consisting of deformation patterns obtained for a number of specially designed composite beam elements, have been obtained. The composite materials applied in the beams consist of glass-fiber reinforced plastic with specially designed layup configurations promoting advanced coupling behavior. Furthermore, the beams are designed with different cross-section shapes. The data obtained from the experiments are also used in order to improve the general understanding related to practical implementation of mechanisms of elastic couplings due to anisotropic properties of composite materials. The knowledge gained from these experiments is therefore essential in order to facilitate an implementation of passive control in future large wind turbine blades. A test setup based on a four-column MTS servo-hydraulic testing machine with a maximum capacity of 100 kN was developed, see Figure 1. The setup allows installing and testing beams of different cross-sections applying load cases such as axial extension, shear force bending, pure bending in two principal directions as well as pure torsion, see Figure 2. In order to apply multi-axial loading, a load application system consisting of three hydraulic actuators were mounted in two planes using multi-axial servo-hydraulic control. The actuator setup consists of the main actuator on the servo-hydraulic test machine working in the vertical axis (depicted on Figure 1 placed at the testing machine crosshead and used for application of vertical forces to the specimens. Two extra actuators are placed in a horizontal plane on the T-slot table of the test machine in different positions in order to apply loading at the tip of the specimen in various configurations. In order to precisely characterize the global as well as surface deformations of the beam specimens tested, a combination of different measurement systems were used during
Balance Component Decomposition and Compensation Method for Unbalanced Load%不平衡负载的平衡分量法分解及补偿方法
Institute of Scientific and Technical Information of China (English)
胡应宏; 王建赜; 任佳佳; 纪延超
2012-01-01
In order to make a better compensation for the three-phase unbalanced load, the unbalanced load was analyzed and a method of reactive compensation admittance calculation based on balance component method was proposed. Any neutral non-grounded three-phase load can be decomposed into a group of balanced load and single line load, and the load compensation admittance can be obtained by the decomposition of the three-phase unbalance load. The load compensation admittance calculation can be divided into three parts, the power factor compensation for the balanced load and the single line load together with the balanced compensation for the single line resistive load. Then, the ideal Steinmetz compensation network algorithm was amended under the condition of asymmetric voltage. A freedom degree existed in this case, and the asymmetry voltage compensation admittance can be accurately calculated according to the control objectives and the revised ideal compensation network calculation method. The rationality and validity of the method was verified using example and simulation. Compared with existing methods, the proposed method has easy calculation and convenient realization.%为了更好地对三相不平衡负荷进行平衡化补偿,对不平衡负载进行详细分析,提出一种新的基于平衡分量法的无功补偿导纳计算方法.首先,将任何中性点不接地的三相负载分解为平衡负载和一个线间负载之和,通过将三相负载进行分解,可以得到负载所需要补偿的导纳值.补偿导纳的计算可分为平衡负载功率因数补偿、线间负载功率因数补偿以及线间线阻性负载平衡化补偿3部分.然后,对系统电压不对称时的Steinmetz.理想补偿网络算法进行修正,根据控制目标和修正后的理想补偿网络算法,计算出系统电压不对称时所需的补偿导纳值.通过算例、仿真分析及实验验证,证明了所提无功补偿导纳计算方法的合理性和正确性,该方
Wang, Yuewu; Wu, Dafang
2016-10-01
Dynamic response of an axially functionally graded (AFG) beam under thermal environment subjected to a moving harmonic load is investigated within the frameworks of classical beam theory (CBT) and Timoshenko beam theory (TBT). The Lagrange method is employed to derive the equations of thermal buckling for AFG beam, and then with the critical buckling temperature as a parameter the Newmark-β method is adopted to evaluate the dynamic response of AFG beam under thermal environments. Admissible functions denoting transverse displacement are expressed in simple algebraic polynomial forms. Temperature-dependency of material constituent is considered. The rule of mixture (Voigt model) and Mori-Tanaka (MT) scheme are used to evaluate the beam's effective material properties. A ceramic-metal AFG beam with immovable boundary condition is considered as numerical illustration to show the thermal effects on the dynamic behaviors of the beam subjected to a moving harmonic load.
A simplified model predicting the weight of the load carrying beam in a wind turbine blade
DEFF Research Database (Denmark)
Mikkelsen, Lars Pilgaard
2016-01-01
Based on a simplified beam model, the loads, stresses and deflections experienced by a wind turbine blade of a given length is estimated. Due to the simplicity of the model used, the model is well suited for work investigating scaling effects of wind turbine blades. Presently, the model is used t...... by the fatigue resistance in orderto making the material survive the 100 to 500 million load cycles experience of the windturbine blade throughout the lifetime. The aluminium blade is also found to be considerably heavier compared with the composite blades....
Tamura, Fumihiko; Hotchi, Hideaki; Schnase, Alexander; Yoshii, Masahito; Yamamoto, Masanobu; Ohmori, Chihiro; Nomura, Masahiro; Toda, Makoto; Shimada, Taihei; Hasegawa, Katsushi; Hara, Keigo
2015-09-01
The rapid cycling synchrotron (RCS) in the Japan Proton Accelerator Research Complex (J-PARC) was originally designed to accelerate two high intensity bunches, while some of neutron experiments in the materials and life science experimental facility and a muon experiment using main ring beams require a single bunch operation mode, in which one of the two rf buckets is filled and the other is empty. The beam intensity in the single bunch operation has been limited by longitudinal beam losses due to the rf bucket distortions by the wake voltage of the odd harmonics (h =1 ,3 ,5 ) in the wide band magnetic alloy cavities. We installed an additional rf feedforward system to compensate the wake voltages of the odd harmonics (h =1 ,3 ,5 ). The additional system has a similar structure as the existing feedforward system for the even harmonics (h =2 ,4 ,6 ). We describe the function of the feedforward system for the odd harmonics, the commissioning methodology, and the commissioning results. The longitudinal beam losses during the single bunch acceleration disappeared with feedforward for the odd harmonics. We also confirmed that the beam quality in the single bunch acceleration are similar to that of the normal operation with two bunches. Thus, high intensity single bunch acceleration at the intensity of 2.3 ×1013 protons per bunch has been achieved in the J-PARC RCS. This article is a follow-up of our previous article, Phys. Rev. ST Accel. Beams 14, 051004 (2011). The feedforward system extension for single bunch operation was successful.
Researches on Fuzzy Creep Compensation of Load Cell%称重传感器蠕变的模糊补偿方法研究
Institute of Scientific and Technical Information of China (English)
朱子健; 陈仁文
2002-01-01
本文介绍了对传感器蠕变进行补偿的新方法,首次引入模糊识别的方法来确定载荷的变化情况,该方法可实现蠕变实时精确补偿,简便易行,避免了繁琐的传感器蠕变模型的建立和实现过程.实验证明这种方法精度很好.%Creep is a critical specification of load cell. Based on the analysis of creep, a new compensation technique, fuzzy creep compensation, is presented in this paper. It firstly introduces the fuzzy recognition to determine loading situations. Compared to the other compensation methods, fuzzy creep compensation can avoid the complicated modeling of creep performance, and it is also proved to be an efficient and simple approach to improve the accuracy of load cell by experiments.
Institute of Scientific and Technical Information of China (English)
范瑞祥; 吴素农; 孙旻; 宋强
2011-01-01
A relocatable cascade distribution static synchronous compensator (D-STATCOM) is presented to meet the power quality requirement of distribution network when impulse loads connecting. Operating with switching capacitor branch, the compensator realizes the synchronous compensation of reactive power. As the example of the application in Jiangxi power grid, the compensation requirement of electric arc furnace which is typical impulse load was analyzed. With field wave recording data and distribution system parameter, simulation model was built. By using frequency dividing coordination control method, the active power compensator can work with switching capacitor branch perfectly. It reduced the dynamic capacity requirement of the compensating system effectively. The active power compensator realized moveable by accepting the cascade main circuit and modularization design. The field application plan of the equipment was put forward. The system parameter configuration method and principle were also given in detail. The operation effect shows that with the fast responding speed and working stability, the equipment can meet the compensation requirement of Var shock in distribution network.%针对冲击性负荷接入配电网后带来的电能质量问题,提出一种基于链式结构的静止同步补偿器(D-STATCOM)的移动型并联有源补偿装置,与固定电容补偿装置形成良好配合,实现了无功的实时动态补偿.以江西电网实例应用为基础,分析以电弧炉为代表的典型冲击性负荷补偿的具体需求,结合现场录波数据和配电系统参数建立仿真模型,应用分频协调控制策略与固定补偿支路形成良好配合,降低了动态容量需求,采用链式主电路和模块化设计实现了有源型补偿装置D-STATCOM的移动化.提出了装置的现场应用方案,给出了基本工程参数的配置方法与原则.投运效果表明,装置响应迅速,运行稳定,能够满足配电网动态无功冲击补偿的要求.
Fiber beam model for fire response simulation of axially loaded concrete filled tubular columns
Ibáñez Usach, Carmen; Romero, Manuel L.; Hospitaler Pérez, Antonio
2013-01-01
This paper presents a fiber beam model for the fire response simulation of concrete filled tubular columns of circular section under concentric axial load. The model consists of two parallel components, one with a circular tubular steel section, and the other with a solid circular concrete section. The components interact with nonlinear longitudinal and transverse links at the end nodes. The element is formulated on a system without rigid body modes and accounts for large displacement geometr...
Numerical Behavior Reproduction of a Truss Structure and Beam, Subjected to Concentrated Load
Nedelcu Dorian; Ianici Draghita; Nedeloni Marian; Daia Daniel
2010-01-01
The paper deals with a numerical reproduction of a real experiment consisting of the same restraints and concentrated load applied to a truss structure and beam; the numerical reproduction was performed with SolidWorks software, where both geometrical reconstruction and finite element analysis were made. The goals of the analysis was to compare the numerical with experimental results and to evaluate the best structure using the structural response criteria.
Numerical Behavior Reproduction of a Truss Structure and Beam, Subjected to Concentrated Load
Directory of Open Access Journals (Sweden)
Nedelcu Dorian
2010-10-01
Full Text Available The paper deals with a numerical reproduction of a real experiment consisting of the same restraints and concentrated load applied to a truss structure and beam; the numerical reproduction was performed with SolidWorks software, where both geometrical reconstruction and finite element analysis were made. The goals of the analysis was to compare the numerical with experimental results and to evaluate the best structure using the structural response criteria.
Thermal Behaviour of Beams with Slant End-Plate Connection Subjected to Nonsymmetric Gravity Load
Directory of Open Access Journals (Sweden)
Farshad Zahmatkesh
2014-01-01
Full Text Available Research on the steel structures with confining of axial expansion in fixed beams has been quite intensive in the past decade. It is well established that the thermal behaviour has a key influence on steel structural behaviours. This paper describes mechanical behaviour of beams with bolted slant end-plate connection with nonsymmetric gravity load, subjected to temperature increase. Furthermore, the performance of slant connections of beams in steel moment frame structures in the elastic field is investigated. The proposed model proved that this flexible connection system could successfully decrease the extra thermal induced axial force by both of the friction force dissipation among two faces of slant connection and a small upward movement on the slant plane. The applicability of primary assumption is illustrated. The results from the proposed model are examined within various slant angles, thermal and friction factors. It can be concluded that higher thermal conditions are tolerable when slanting connection is used.
Fatigue crack behavior of RC beams strengthened with CFL under cylic bending loads
Zheng, Xiaohong; Huang, Peiyan; Guo, Xinyan
2008-11-01
A mechanical model of cracked reinforced concrete (RC) beams strengthened with carbon fiber laminate (CFL) is proposed to establish the theoretical relationship among the crack height (a), the number of fatigue loading cycles (n), and the fatigue life (N), and the main crack growth behavior is discussed. Moreover, some fatigue tests of the RC beams strengthened with CFL were carried out on material testing system (MTS) to investigate the crack growth rate (da/dn). The analysis results show that the crack growth behavior of RC beams strengthened with CFL may be divided into three stages: 1) initiation and rapid growth, 2) steady growth and arrest, 3) unstable growth. At the stage of crack steady growth and arrest, the relationship among, da/dn, n, and N could be expressed as: da/dn=C/(nlnN), where the constant coefficient, C, is determined from the fatigue tests.
A closed-form solution to a viscoelastically supported Timoshenko beam under harmonic line load
Luo, W. L.; Xia, Y.; Zhou, X. Q.
2016-05-01
This study aims to formulate a closed-form solution to a viscoelastically supported Timoshenko beam under a harmonic line load. The differential governing equations of motion are converted into algebraic equations by assuming the deflection and rotation of the beam in harmonic forms with respect to time and space. The characteristic equation is biquadratic and thus contains 14 explicit roots. These roots are then substituted into Cauchy's residue theorem; consequently, five forms of the closed-form solution are generated. The present solution is consistent with that of an Euler-Bernoulli beam on a Winkler foundation, which is a special case of the present problem. The current solution is also verified through numerical examples.
Analysis of the Dynamic Response in Blast-Loaded CFRP-Strengthened Metallic Beams
Directory of Open Access Journals (Sweden)
Zhenyu Wang
2013-01-01
Full Text Available Carbon fiber-reinforced polymer composites (CFRPs are good candidates in enhancing the blast resistant performance of vulnerable public buildings and in reinforcing old buildings. The use of CFRP in retrofitting and strengthening applications is traditionally associated with concrete structures. Nevertheless, more recently, there has been a remarkable aspiration in strengthening metallic structures and components using CFRP. This paper presents a relatively simple analytical solution for the deformation and ultimate strength calculation of hybrid metal-CFRP beams when subjected to pulse loading, with a particular focus on blast loading. The analytical model is based on a full interaction between the metal and the FRP and is capable of producing reasonable results in a dynamic loading scenario. A nonlinear finite element (FE model is also developed to reveal the full dynamic behavior of the CFRP-epoxy-steel hybrid beam, considering the detailed effects, that is, large strains, high strain rates in metal, and different failure modes of the hybrid beam. Experimental results confirm the analytical and the FE results and show a strong correlation.
Directory of Open Access Journals (Sweden)
Fangping Liu
2016-01-01
Full Text Available Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equations, the level-S nonlinear evolution model of fatigue strain was constructed, and the physical meaning of the parameters was discussed. Finally, the evolution of fatigue strain and fatigue damage of concrete in the compression zone of the experimental beam was analyzed based on the level-S nonlinear evolution model. The results show that, initially, fatigue strain grows rapidly. In the middle stages, fatigue strain is nearly a linear change. Because the experimental data for the third stage are relatively scarce, the evolution of the strain therefore degenerated into two phases. The model has strong adaptability and high accuracy and can reflect the evolution of fatigue strain. The fatigue damage evolution expression based on fatigue strain shows that fatigue strain and fatigue damage have similar variations, and, with the same load cycles, the greater the load level, the larger the damage, in line with the general rules of damage.
Simulation of Fatigue Stiffness Degradation in Prestressed Concrete Beams under Cyclic Loading
Institute of Scientific and Technical Information of China (English)
Junqing Lei; Shanshan Cao; Guoshan Xu; Yun Xiao
2016-01-01
In order to investigate and research the fatigue cracking of prestressed concrete fatigue properties and loading and stiffness degeneration process, cyclic loading tests were carried out on six prestressed concrete beams and the stiffness degradation under fatigue was investigated. A simulation model of stiffness degradation is proposed based on the stiffness analysis of the fatigue⁃damaged section. The elastic modulus of damaged concrete and the effective residual area of steel were introduced as well as an adjusted three⁃stage concrete fatigue damage evolution model. The strip method was used to analyze concrete damage due to changing stress along the depth of the beam section. The simulation and test results were compared and a method of predicting fatigue deflection was presented based on the simulation model. The predicted results were compared with that of the neural network method. It is in good agreement for the simulation results with the test results. It is only less than 5% error for the simulation model which can reveal the two⁃stage degradation of prestressed concrete beams under cyclic loading. It is more precise for the simulation prediction method under proper conditions.
Torabizadeh, Mohammad Amin
2013-07-01
A new method is developed to derive equilibrium equations of Metal-Ceramic beams based on first order shear deformation plate theory which is named first order shear deformation beam theory2(FSDBT2). Equilibrium equations obtained from conventional method (FSDBT1) is compared with FSDBT2 and the case of cylindrical bending of Metal-Ceramic composite plates for non-linear thermomechanical deformations and various loadings and boundary conditions. These equations are solved by using three different methods (analytical, perturbation technique and finite element solution). The through-thickness variation of the volume fraction of the ceramic phase in a Metal-Ceramic beam is assumed to be given by a power-law type function. The non-linear strain-displacement relations in the von-Kármán sense are used to study the effect of geometric non-linearity. Also, four other representative averaging estimation methods, the linear rule, Mori-Tanaka, Self-Consistent and Wakashima-Tsukamoto schemes, by comparing with the power-law type function are also investigated. Temperature distribution through the thickness of the beams in thermal loadings is obtained by solving the one-dimensional heat transfer equation. Finally it is concluded that for Metal-Ceramic composites, these two theories result in identical static responses. Also the displacement field and equilibrium equations in the case of cylindrical bending of Metal-Ceramic plates are the same as those supposed in FSDBT2.
Institute of Scientific and Technical Information of China (English)
Miha Brojan; Matjaz Cebron; Franc Kosel
2012-01-01
This work studies large deflections of slender,non-prismatic cantilever beams subjected to a combined loading which consists of a non-uniformly distributed continuous load and a concentrated load at the free end of the beam.The material of the cantilever is assumed to be nonlinearly elastic.Different nonlinear relations between stress and strain in tensile and compressive domain are considered.The accuracy of numerical solutions is evaluated by comparing them with results from previous studies and with a laboratory experiment.
Vibration suppression of curved beams traversed by off-center moving loads
Rostam, M. R.; Javid, F.; Esmailzadeh, E.; Younesian, D.
2015-09-01
In this study six different vibration control strategies are proposed to suppress both the flexural and torsional vibrations of a curved beam traversed by off-center moving loads. The various vibration control strategies employed are: (i) separate tuned-mass-dampers (TMDs), (ii) linked TMDs with a massless connecting rod, (iii) distributed TMDs system, (iv) linked TMDs with intermediate connection, (v) separate TMDs with intermediate dissipating system, and finally (vi) the nonlinear energy sinks (NESs). The curved beam is modeled using finite element model. An optimal design of TMD system is proposed to suppress the effect of non-symmetrical and side-way motion of vehicles traveling on bridges. The dynamic performance of the proposed vibration control strategies are thoroughly evaluated while subjected to different loading conditions: (a) successive moving loads and (b) broadband random excitation. It is shown that while all the proposed strategies can remarkably suppress both types of the vibration, the fifth strategy is the most effective one that provides the largest value of the bending and torsional vibration reduction in the first loading condition.
Temperature error compensation for load cell based on RBFNN*%基于RBFNN的称重传感器温度误差补偿
Institute of Scientific and Technical Information of China (English)
杨进宝; 倪芳英; 张建军
2011-01-01
Load cell has nonlinear error because of different ambient temperature in work, and it is necessary to compensate. The principle of temperature error of load cell is illustrated, and a method for compensating this error based on radial basis function neural network (RBFNN) is proposed. The training algorithm of RBFNN is described. Using this proposed temperature error compensation method and the load cell which the weighing range is 100 kg,the experiments are implemented under 0 ～60℃. The results show that temperature errors of load cell are decreased, and its weighing accuracy is increased.%称重传感器存在因环境温度不同导致的非线性误差,需要进行补偿.阐述了称重传感器的温度误差机理,提出了一种基于径向基函数神经网络(RBFNN)的称重传感器温度误差补偿方法,并给出了训练算法.采用该方法,利用量程为100kg的称重传感器,在0～60℃范围内进行温度误差补偿实验.实验表明:采用这种方法补偿后,称重传感器温度误差大大减少,提高了称重准确度.
Institute of Scientific and Technical Information of China (English)
XIA Zhi-fan; WANG Jian-hua; XU Bin; LU Jian-fei
2009-01-01
The expression of the equivalent stiffness of the saturated poro-elastic half space interacting with an infinite beam to harmonic moving loads is obtained via the Fourier transformation method in the frequency wave number domain. Based on the obtained equivalent stiffness, the frequency wave number domain solution of the beam-half-space system is obtained by the compatibility condition between the beam and the half space.Critical velocity of harmonic moving loads along an infinite Euler-Bernoulli elastic beam is determined. The time domain solutions for the beam and the saturated poro-elastic half space are derived by means of the inverse Fourier transformation method. Also, the influences of the load speed, frequency and material parameters of the poro-elastic half space on the responses of the beam are investigated. Numerical results show that the frequency corresponding to the maximum deflection and bending moment increases with increasing load speed. Moreover,it can be seen that at higher frequencies, the dynamic response is independent of the load speed. The present results also show that for a beam overlying a saturated poro-elastic half space, there still exist critical velocities even when the load velocity is larger than the shear wave speed of the medium.
Method for adaptive compensation of load cell's nonlinear error%称重传感器非线性误差自适应补偿方法
Institute of Scientific and Technical Information of China (English)
杨进宝; 汪鲁才
2011-01-01
The nonlinear error of load cell is not same in weight range. The character of load cell's nonlinear error is formulated and a method for adaptive compensation is proposed. The nonlinear error compensation network based on Radial Basis Function Neural Network(RBFNN) is used in upper limit of load cell' weighing range, the digital filter is applied in the low limit range,and the load cell is not compensated in the middle range.The adaptive selective network is use to choose the subnet for error compensation.The experimental results show that the maximum relative error of load cell with this method respectively drops from 0.2％ in its lower interval scale,0.4％ in its middle interval scale, and 1.37％ in its upper interval scale without compensation to 0.16％,0.04％,and 0.07％ after compensation,and its weighing result is more accurate.%额定量程内称重传感器的非线性误差不同,为此阐述了称重传感器的非线性误差特性,提出了一种非线性误差自适应分.段补偿方法:在额定量程的上限区,采用基于径向基函数神经网络(RBFNN)的补偿网络完成传感器非线性误差补偿;在下限区,采用数字滤波器完成非线性误差补偿;在中间区,传感器不补偿.同时利用自适应选择网络,完成了分段补偿的选择.实验表明,采用这种方法补偿后的称重传感器下限区、中间区与上限区的最大相对误差分别由补偿前的0.2%、0.4%,1.37%下降到0.16%,0.04%、0.07%,补偿效果明显.
农村电网不对称负荷补偿方法研究%Study on compensation method of unbalanced load in rural power grid
Institute of Scientific and Technical Information of China (English)
房俊龙; 于洪涛; 马文川; 蔡银哿; 杨庆忠; 杨国良
2014-01-01
The paper proposed TCR type static var compensator based on Steinmetz theory which it could be used in the rural power grid, it could compensate unbalanced load and improve power factor in the meantime. The results showed that method could effectively make three-phase load balance, while increasing the power factor, had a certain theoretical and application value.%文章提出在农村电网中采用基于Steinmetz电路理论的TCR型静止无功补偿器，平衡三相不对称负荷，提高系统功率因数。仿真验证结果表明，该方法能使三相负荷平衡，提高功率因数，具有一定理论意义及应用价值。
A simplified model predicting the weight of the load carrying beam in a wind turbine blade
Mikkelsen, Lars P.
2016-07-01
Based on a simplified beam model, the loads, stresses and deflections experienced by a wind turbine blade of a given length is estimated. Due to the simplicity of the model used, the model is well suited for work investigating scaling effects of wind turbine blades. Presently, the model is used to predict the weight of the load carrying beam when using glass fibre reinforced polymers, carbon fibre reinforced polymers or an aluminium alloy as the construction material. Thereby, it is found that the weight of a glass fibre wind turbine blade is increased from 0.5 to 33 tons when the blade length grows from 20 to 90 m. In addition, it can be seen that for a blade using glass fibre reinforced polymers, the design is controlled by the deflection and thereby the material stiffness in order to avoid the blade to hit the tower. On the other hand if using aluminium, the design will be controlled by the fatigue resistance in order to making the material survive the 100 to 500 million load cycles experience of the wind turbine blade throughout the lifetime. The aluminium blade is also found to be considerably heavier compared with the composite blades.
煤矿低压系统动态无功补偿优化%Optimization of Reactive-load Compensation of Low Voltage System in Coal Mine
Institute of Scientific and Technical Information of China (English)
刘天野
2014-01-01
针对煤矿低压供电系统中功率因数低、电能质量不稳等问题，对煤矿低压系统无功功率补偿应用情况进行了研究。在分析了无功功率补偿方式和原理的基础上，提出了煤矿低压系统无功补偿优化算法，使线损在矿区低压系统无功平衡条件下达到最小。%Aiming at low power factor and instable electric energy quality of low voltage power supply system in coal mine ,this paper studied reactive-load compensation in low voltage system .On the basis of analysis of the reactive-load compensation principle and method ,the algorithm for optimization of reactive-load compensation in low voltage system was proposed ,achieving minimum line loss in the condition of balanced reactive component .
E. Mardani
2008-01-01
A prismatic beam made of a behaviorally nonlinear material was analyzed under a concentrated load moving with a known velocity on a nonlinear elastic foundation with a reaction the vibration equation of motion was derived using Hamilton principle and Euler Lagrange equation. The amplitude of vibration, circular frequency, bending moment, stress and deflection of the beam can be calculated by the presented solution. Considering the response of the beam, in the sense of its resonance, it was fo...
Oscillations of a Beam on a Non-Linear Elastic Foundation under Periodic Loads
Directory of Open Access Journals (Sweden)
Donald Mark Santee
2006-01-01
Full Text Available The complexity of the response of a beam resting on a nonlinear elastic foundation makes the design of this structural element rather challenging. Particularly because, apparently, there is no algebraic relation for its load bearing capacity as a function of the problem parameters. Such an algebraic relation would be desirable for design purposes. Our aim is to obtain this relation explicitly. Initially, a mathematical model of a flexible beam resting on a non-linear elastic foundation is presented, and its non-linear vibrations and instabilities are investigated using several numerical methods. At a second stage, a parametric study is carried out, using analytical and semi-analytical perturbation methods. So, the influence of the various physical and geometrical parameters of the mathematical model on the non-linear response of the beam is evaluated, in particular, the relation between the natural frequency and the vibration amplitude and the first period doubling and saddle-node bifurcations. These two instability phenomena are the two basic mechanisms associated with the loss of stability of the beam. Finally Melnikov's method is used to determine an algebraic expression for the boundary that separates a safe from an unsafe region in the force parameters space. It is shown that this can be used as a basis for a reliable engineering design criterion.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Analytical and semi-analytical solutions are presented for anisotropic functionally graded beams subject to an arbitrary load,which can be expanded in terms of sinusoidal series.For plane stress problems,the stress function is assumed to consist of two parts,one being a product of a trigonometric function of the longitudinal coordinate(x) and an undetermined function of the thickness coordinate(y),and the other a linear polynomial of x with unknown coefficients depending on y.The governing equations satisfied by these y-dependent functions are derived.The expressions for stresses,resultant forces and displacements are then deduced,with integral constants determinable from the boundary conditions.While the analytical solution is derived for the beam with material coefficients varying exponentially or in a power law along the thickness,the semi-analytical solution is sought by making use of the sub-layer approximation for the beam with an arbitrary variation of material parameters along the thickness.The present analysis is applicable to beams with various boundary conditions at the two ends.Three numerical examples are presented for validation of the theory and illustration of the effects of certain parameters.
Institute of Scientific and Technical Information of China (English)
HUANG DeJin; DING Haodiang; CHEN WeiQiu
2009-01-01
Analytical and semi-analytical solutions are presented for anisotropic functionally graded beams sub-ject to an arbitrary load, which can be expanded in terms of sinusoidal series. For plane stress prob-lems, the stress function is assumed to consist of two parts, one being a product of a trigonometric function of the longitudinal coordinate (x) and an undetermined function of the thickness coordinate (y), and the other a linear polynomial of x with unknown coefficients depending on y. The governing equa-tions satisfied by these y-dependent functions are derived. The expressions for stresses, resultant forces and displacements are then deduced, with integral constants determinable from the boundary conditions. While the analytical solution is derived for the beam with material coefficients varying exponentially or in a power law along the thickness, the semi-analytical solution is sought by making use of the sub-layer approximation for the beam with an arbitrary variation of material parameters along the thickness. The present analysis is applicable to beams with various boundary conditions at the two ends. Three numerical examples are presented for validation of the theory and illustration of the effects of certain parameters.
Flexural analysis of deep beam subjected to parabolic load using refined shear deformation theory
Directory of Open Access Journals (Sweden)
Ghugal Y. M.
2012-12-01
Full Text Available A trigonometric shear deformation theory for flexure of thick or deep beams, taking into account transverse shear deformation effects, is developed. The number of variables in the present theory is same as that in the first order shear deformation theory. The sinusoidal function is used in displacement field in terms of thickness coordinate to represent the shear deformation effects. The noteworthy feature of this theory is that the transverse shear stresses can be obtained directly from the use of constitutive relations with excellent accuracy, satisfying the shear stress free conditions on the top and bottom surfaces of the beam. Hence, the theory obviates the need of shear correction factor. Governing differential equations and boundary conditions are obtained by using the principle of virtual work. The thick isotropic beams are considered for the numerical studies to demonstrate the efficiency of the theory. It has been shown that the theory is capable of predicting the local effect of stress concentration due to fixity of support. The fixed isotropic beams subjected to parabolic loads are examined using the present theory. Results obtained are discussed critically with those of other theories.
Neutron spectra at two beam ports of a TRIGA Mark III reactor loaded with HEU fuel.
Vega-Carrillo, H R; Hernández-Dávila, V M; Aguilar, F; Paredes, L; Rivera, T
2014-01-01
The neutron spectra have been measured in two beam ports, one radial and another tangential, of the TRIGA Mark III nuclear reactor from the National Institute of Nuclear Research in Mexico. Measurements were carried out with the reactor core loaded with high enriched uranium fuel. Two reactor powers, 5 and 10 W, were used during neutron spectra measurements using a Bonner sphere spectrometer with a (6)LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter high-density polyethylene spheres. The neutron spectra were unfolded using the NSDUAZ unfolding code. For each spectrum total flux, mean energy and ambient dose equivalent were determined. Measured spectra show fission, epithermal and thermal neutrons, being harder in the radial beam port. PMID:23746708
Neutron spectra at two beam ports of a TRIGA Mark III reactor loaded with HEU fuel.
Vega-Carrillo, H R; Hernández-Dávila, V M; Aguilar, F; Paredes, L; Rivera, T
2014-01-01
The neutron spectra have been measured in two beam ports, one radial and another tangential, of the TRIGA Mark III nuclear reactor from the National Institute of Nuclear Research in Mexico. Measurements were carried out with the reactor core loaded with high enriched uranium fuel. Two reactor powers, 5 and 10 W, were used during neutron spectra measurements using a Bonner sphere spectrometer with a (6)LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter high-density polyethylene spheres. The neutron spectra were unfolded using the NSDUAZ unfolding code. For each spectrum total flux, mean energy and ambient dose equivalent were determined. Measured spectra show fission, epithermal and thermal neutrons, being harder in the radial beam port.
Zhang, Tong; Deng, Haixiao; Wang, Dong; Dai, Zhimin; Zhao, Zhentang
2013-01-01
All-optical schemes provide a potential to dramatically cut off the size and cost of x-ray light sources to the university-laboratory scale, with the combination of the laser-plasma accelerator and the laser undulator. However, the large longitudinal energy spread of the electron beam from laser-plasma accelerator may hinder the way to high brightness of these all-optical light sources. In this letter, the beam energy spread effect is proposed to be significantly compensated by the natural transverse gradient of a laser undulator when properly dispersing the electron beam transversely. Theoretical analysis and numerical simulations on conventional laser-Compton scattering sources and high-gain all-optical x-ray free-electron lasers with the electron beams from laser-plasma accelerators are presented.
DEFF Research Database (Denmark)
Andersen, Lars; Nielsen, Søren R.K.; Kirkegaard, Poul Henning
2001-01-01
The paper deals with the finite element method (FEM) solution of the problem with loads moving uniformly along an infinite Euler beam supported by a linear elastic Kelvin foundation with linear viscous damping. Initially, the problem is formulatedin a moving co-ordinate system following the load...
ZHANG, Tong; Feng, Chao; Deng, Haixiao; Wang, Dong; Dai, Zhimin; Zhao, Zhentang
2013-01-01
All-optical ideas provide a potential to dramatically cut off the size and cost of x-ray light sources to the university-laboratory scale, with the combination of the laser-plasma accelerator and the laser undulator. However, the large longitudinal energy spread of the electron beam from laser-plasma accelerator may hinder the way to high brightness of these all-optical light sources. In this paper, the beam energy spread effect is proposed to be significantly compensated by the natural trans...
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The bending problem of a functionally graded anisotropic cantilever beam subjected to thermal and uniformly distributed load is investigated, with material parameters being arbitrary functions of the thickness coordinate. The heat conduction problem is treated as a 1D problem through the thickness. Based on the elementary formulations for plane stress problem, the stress function is assumed to be in the form of polynomial of the longitudinal coordinate variable, from which the stresses can be derived.The stress function is then determined completely with the compatibility equation and boundary conditions. A practical example is presented to show the application of the method.
ANALYTICAL SOLUTION FOR FIXED-FIXED ANISOTROPIC BEAM SUBJECTED TO UNIFORM LOAD
Institute of Scientific and Technical Information of China (English)
DING Hao-jiang; HUANG De-jin; WANG Hui-ming
2006-01-01
The analytical solutions of the stresses and displacements were obtained for fixed-fixed anisotropic beams subjected to uniform load. A stress function involving unknown coefficients was constructed, and the general expressions of stress and displacement were obtained by means of Airy stress function method. Two types of the description for the fixed end boundary condition were considered. The introduced unknown coefficients in stress function were determined by using the boundary conditions. The analytical solutions for stresses and displacements were finally obtained. Numerical tests show that the analytical solutions agree with the FEM results. The analytical solution supplies a classical example for the elasticity theory.
Institute of Scientific and Technical Information of China (English)
HUANG De-jin; DING Hao-jiang; CHEN Wei-qiu
2007-01-01
The bending problem of a functionally graded anisotropic cantilever beam subjected to a linearly distributed load is investigated. The analysis is based on the exact elasticity equations for the plane stress problem. The stress function is introduced and assumed in the form of a polynomial of the longitudinal coordinate. The expressions for stress components are then educed from the stress function by simple differentiation.The stress function is determined from the compatibility equation as well as the boundary conditions by a skilful deduction. The analytical solution is compared with FEM calculation, indicating a good agreement.
Experimental Tests and FEM Model for SFRC Beams under Flexural and Shear Loads
Colajanni, Piero; La Mendola, Lidia; Priolo, Salvatore; Spinella, Nino
2008-07-01
The complete load-vs-displacement curves obtained by four-point-bending tests on Steel Fiber Reinforced Concrete (SFRC) beams are predicted by using a nonlinear finite element code based on the Modified Compression Field Theory (MCFT) and the Disturbed Stress Field Model (DSFM) suitably adapted for SFRC elements. The effect of fibers on the shear-flexure response is taken into account, mainly incorporating tensile stress-strain analytical relationship for SFRC. The numerical results show the effectiveness of the model for prediction of the behavior of the tested specimens reinforced with light amount of stirrups or with fibers only.
Beam Test of a Dielectric Loaded High Pressure RF Cavity for Use in Muon Cooling Channels
Energy Technology Data Exchange (ETDEWEB)
Freemire, Ben [IIT, Chicago; Bowring, Daniel [Fermilab; Kochemirovskiy, Alexey [Chicago U.; Moretti, Alfred [Fermilab; Peterson, David [Fermilab; Tollestrup, Alvin [Fermilab; Torun, Yagmur [IIT, Chicago; Yonehara, Katsuya [Fermilab
2016-06-01
Bright muon sources require six dimensional cooling to achieve acceptable luminosities. Ionization cooling is the only known method able to do so within the muon lifetime. One proposed cooling channel, the Helical Cooling Channel, utilizes gas filled radio frequency cavities to both mitigate RF breakdown in the presence of strong, external magnetic fields, and provide the cooling medium. Engineering constraints on the diameter of the magnets within which these cavities operate dictate the radius of the cavities be decreased at their nominal operating frequency. To accomplish this, one may load the cavities with a larger dielectric material. A 99.5% alumina ring was inserted in a high pressure RF test cell and subjected to an intense proton beam at the MuCool Test Area at Fermilab. The results of the performance of this dielectric loaded high pressure RF cavity will be presented.
Directory of Open Access Journals (Sweden)
Krishna Lok Singh
2014-07-01
Full Text Available In this article, the delamination onset and growth behavior of double cantilever beam (DCB specimens has been presented. The modeling of a debonded region using master and slave surface technique for DCB specimens is done in ABAQUS CAE. The analysis of DCB specimens comprising of fatigue cyclic load has been done in ABAQUS. An onset and Paris delamination growth regimes are plotted. The growth regime being linear in log-log scale, the prediction of constants of this regime has been obtained using the polyfit command in the MATLAB environment. To obtain these constants has been explained in this article. Comparison of experimental and analytical results is shown for delamination growth. The strain energy release rate values for threshold and critical are indicated on the graphs. The number of cycles for delamination onset and growth has been tabulated for various load cases.
Dong, Biqin; Liu, Yuqing; Qin, Lei; Wang, Yaocheng; Fang, Yuan; Xing, Feng; Chen, Xianchuan
2015-10-01
In this paper, the application of a novel cement-based piezoelectric ceramic sensor is stated for the in situ stress monitoring of the reinforced concrete beam under static loading. Smart beam composite structures were designed and characterised by a range of experimental methods. Finite element analysis is used to analyse the mechanical response of the concrete beam under static loading. The results show that the mechanical-electrical response of sensors embedded in reinforced concrete beams follows a linear relationship under various loading conditions. The sensors are able to record the stress history of the beam under static loads. Moreover, the measured stress data agree well with the simulated results and the smart structures are found to be capable of reliably monitoring the response of a beam during stress testing for static loading modes to real concrete structures. The study indicates that such cement-based piezoelectric composites have a high feasibility and applicability to the in situ stress monitoring of reinforced concrete structures.
Chunhong, Zhang; Haigang, Yang; Shi, Richard
2013-06-01
A synchronous buck DC—DC converter with an adaptive multi-mode controller is proposed. In order to achieve high efficiency over its entire load range, pulse-width modulation (PWM), pulse-skip modulation (PSM) and pulse-frequency modulation (PFM) modes were integrated in the proposed DC—DC converter. With a highly accurate current sensor and a dynamic mode controller on chip, the converter can dynamically change among PWM, PSM and PFM control according to the load requirements. In addition, to avoid power device damage caused by inrush current at the start up state, a soft-start circuit is presented to suppress the inrush current. Furthermore, an adaptive slope compensation (SC) technique is proposed to stabilize the current programmed PWM controller for duty cycle passes over 50%, and improve the degraded load capability due to traditional slope compensation. The buck converter chip was simulated and manufactured under a 0.35 μm standard CMOS process. Experimental results show that the chip can achieve 79% to 91% efficiency over the load range of 0.1 to 1000 mA
Institute of Scientific and Technical Information of China (English)
Zhang Chunhong; Yang Haigang; Richard Shi
2013-01-01
A synchronous buck DC-DC converter with an adaptive multi-mode controller is proposed.In order to achieve high efficiency over its entire load range,pulse-width modulation (PWM),pulse-skip modulation (PSM)and pulse-frequency modulation (PFM) modes were integrated in the proposed DC-DC converter.With a highly accurate current sensor and a dynamic mode controller on chip,the converter can dynamically change among PWM,PSM and PFM control according to the load requirements.In addition,to avoid power device damage caused by inrush current at the start up state,a soft-start circuit is presented to suppress the inrush current.Furthermore,an adaptive slope compensation (SC) technique is proposed to stabilize the current programmed PWM controller for duty cycle passes over 50％,and improve the degraded load capability due to traditional slope compensation.The buck converter chip was simulated and manufactured under a 0.35μm standard CMOS process.Experimental results show that the chip can achieve 79％ to 91％ efficiency over the load range of 0.1 to 1000 mA.
International Nuclear Information System (INIS)
This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth
Energy Technology Data Exchange (ETDEWEB)
Yu, Linwen [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Université de Sherbrooke, Quebec (Canada); François, Raoul, E-mail: raoul.francois@insa-toulouse.fr [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Dang, Vu Hiep [Hanoi Architectural University, Faculty of Civil Engineering, Hanoi (Viet Nam); L' Hostis, Valérie [CEA Saclay, CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, Gif-sur-Yvette (France); Gagné, Richard [Université de Sherbrooke, Quebec (Canada)
2015-01-15
This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth.
Directory of Open Access Journals (Sweden)
BOUROUIS FAIROUZ
2012-04-01
Full Text Available Sandwich beams loaded in three points bending may fail in several ways including tension or compression failure of facings. In this paper , The effect of the transverse shear on the face yielding and face wrinkling failure modes of sandwich beams loaded in three points bending have been studied, the beams were made of various composites materials carbon/epoxy, kevlar/epoxy, glass/epoxy at sequence [+θ/-θ]3s, [0°/90°]3s. . The stresses in the face were calculated using maximum stress criterion and the simple beam theory. The obtained different results show that the sandwich beams with carbon/epoxy, and glass/epoxy face sheets are the best materials, inreturn the kevlar /epoxy facing characterised by low resistance of transverse shear in compression and tensile.
舵机负载模拟器惯量失配加载补偿方法%Missile Actuator Load Simulator Inertia Mismatch Compensation Methods
Institute of Scientific and Technical Information of China (English)
陶渝辉; 王战
2012-01-01
The compensation methods are discussed when load simulator inertia is greater than missile control surface inertia. Errors of missile actuator torque and deflection angle exist in simulation using compensation. The approaches are presented to improve simulation according to different errors. Analysis results show that the compensation method is useable and valuable to many missile actuator load simulations.%针对舵机负载力矩模拟器输出等效惯量大于被加载舵机舵面惯量的舵机加载试验情况,研究了其力矩加载补偿方法,分析了其力矩加载误差,提出了针对不同误差源的提高仿真精度的技术途径.分析结果表明,此力矩加载补偿方法现实可行,提高了试验资源的利用率,具有较好的经济效益和现实意义.
Energy Technology Data Exchange (ETDEWEB)
Ruehrnschopf, Ernst-Peter; Klingenbeck, Klaus [Siemens AG, Healthcare Sector, Imaging and Therapy Division, Forchheim (Germany)
2011-07-15
Since scattered radiation in cone-beam volume CT implies severe degradation of CT images by quantification errors, artifacts, and noise increase, scatter suppression is one of the main issues related to image quality in CBCT imaging. The aim of this review is to structurize the variety of scatter suppression methods, to analyze the common structure, and to develop a general framework for scatter correction procedures. In general, scatter suppression combines hardware techniques of scatter rejection and software methods of scatter correction. The authors emphasize that scatter correction procedures consist of the main components scatter estimation (by measurement or mathematical modeling) and scatter compensation (deterministic or statistical methods). The framework comprises most scatter correction approaches and its validity also goes beyond transmission CT. Before the advent of cone-beam CT, a lot of papers on scatter correction approaches in x-ray radiography, mammography, emission tomography, and in Megavolt CT had been published. The opportunity to avail from research in those other fields of medical imaging has not yet been sufficiently exploited. Therefore additional references are included when ever it seems pertinent. Scatter estimation and scatter compensation are typically intertwined in iterative procedures. It makes sense to recognize iterative approaches in the light of the concept of self-consistency. The importance of incorporating scatter compensation approaches into a statistical framework for noise minimization has to be underscored. Signal and noise propagation analysis is presented. A main result is the preservation of differential-signal-to-noise-ratio (dSNR) in CT projection data by ideal scatter correction. The objective of scatter compensation methods is the restoration of quantitative accuracy and a balance between low-contrast restoration and noise reduction. In a synopsis section, the different deterministic and statistical methods are
Beam induced heat loads on the beam-screens of the twin-bore magnets in the IRs of the HL-LHC
Iadarola, Giovanni; Rumolo, Giovanni
2016-01-01
The expected heat load induced on the beam screens has been evaluated for all the twin-bore magnets in the Insertion Regions (IRs) of the HL-LHC. The contribution from the impedance of the beam screen has been evaluated taking into account the presence of a longitudinal weld in the beam screen and the impact of the temperature and of the magnetic field on the resistivity of the surface. The contribution coming from electron cloud effects has been evaluated for different values of the Secondary Electron Yield of the surface based PyECLOUD build-up simulations.
液压振动台负载流量补偿方法的研究%Study on load-flow compensation of hydraulic vibration table
Institute of Scientific and Technical Information of China (English)
刘博; 侯京锋; 窦雪川; 张静; 郝岩研; 王家乐; 王有杰
2014-01-01
通过将负载变化折算为相应控制指令，并与期望指令相叠加后，作为最终的控制指令输出给伺服阀，构造负载流量与期望控制指令之间的比例关系，实现了液压振动台抑制负载干扰对流量波动的影响，提高了液压振动台运动控制精度。经过流量补偿后的液压振动台在负载变化时可以实现对输入指令较好的跟踪，可对机械振动或冲击环境进行更好的模拟。%By superposing the control command converted from the varying load and the expected control command as the last control command, the linear dependency between the load-flow and the expected control command is constructed. The method could achieve the suppression of load-flow fluctuation influenced by load variation, and improve the control precision of the table. The hydraulic vibration table could track the expected command with load varying well by the load-flow compensation method, and simulate the vibration environment and the shock environment better.
A NEW HYSTERESIS COMPENSATION METHOD FOR LOAD CELLS%称重传感器的一种新的滞后补偿方法
Institute of Scientific and Technical Information of China (English)
朱子健; 陈仁文
2002-01-01
A new hysteresis compensation method is presented. After analyzing the characteristics of strain-gage based load cells under loading & unloading conditions, mathematical models are established. A solution to compensate the hysteresis of the load cell by software in the terminal is brought forward and is verified by the experiments. It is shown that the method is reliable and can effectively reduce the hysteresis.%通过对电阻应变式称重传感器在各种加载卸载情况下的滞后特性的分析,建立了其相应的数学模型,并初步探讨了一种可以通过程序在仪表中对传感器的重要指标-滞后进行补偿从而提高整个传感器的精度的方法.最后,对以上方法进行了验证性试验,证明了补偿方法的可行性.
Institute of Scientific and Technical Information of China (English)
Victor S. Kamara; LIU Xila(刘西拉)
2004-01-01
The tied-arch action was analyzed by considering 27 reinforced-concrete beams without web reinforcements that were dismantled from a wide range of deteriorated coastal and marine structures and with varying degrees of reinforcement corrosion. Under 2-point loading and changing shear span ratio, changes in loading capacity for beams of the same corrosion degree were studied. Formulas relating ultimate moment of reinforcements with the same corrosion level at increasing a/d ratio were then developed. Load-carrying capacity profile for beams with reinforcement corrosion of 1% and the same cross section was described. The minimum ultimate moment occurs at a/d = 2.5 and at 52% of the full flexural moment, suggesting that the difference in ultimate moment between theoretical and experimental results at the minimum point equals 11%. The results show that the developed theoretical relations compared well with experimental values.
Rezvanil, Mohammad Javad; Kargarnovin, Mohammad Hossein; Younesian, Davood
2011-12-01
The response of an infinite Timoshenko beam subjected to a harmonic moving load based on the thirdorder shear deformation theory (TSDT) is studied. The beam is made of laminated composite, and located on a Pasternak viscoelastic foundation. By using the principle of total minimum potential energy, the governing partial differential equations of motion are obtained. The solution is directed to compute the deflection and bending moment distribution along the length of the beam. Also, the effects of two types of composite materials, stiffness and shear layer viscosity coefficients of foundation, velocity and frequency of the moving load over the beam response are studied. In order to demonstrate the accuracy of the present method, the results TSDT are compared with the previously obtained results based on first-order shear deformation theory, with which good agreements are observed.
Shock loading characteristics of Zr and Ti metals using dual beam velocimeter
Energy Technology Data Exchange (ETDEWEB)
Saxena, A. K., E-mail: a-saxena@barc.gov.in; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)
2015-08-21
The characteristics of titanium and zirconium metal foils under shock loading have been studied up to 16 GPa and 12 GPa pressure, respectively, using portable electric gun setup as projectile launcher. In these experiments, the capabilities of a single Fabry-Perot velocimeter have been enhanced by implementing it in dual beam mode to record the two velocity profiles on a single streak camera. The measured equation of state data for both the metals have been found to be well in agreement with the reported Hugoniot, within experimental accuracies. A phase transition from α to ω phase has been detected near to 11.4 GPa for titanium and 8.2 GPa for zirconium in the rising part of target-glass interface velocity profile.
Institute of Scientific and Technical Information of China (English)
GU Yi; ZHANG Yong-Gang
2008-01-01
We investigate the properties of symmetrical triangular quantum wells composed of InGaAs/InAs chirped superlattice,which is grown by gas source molecular beam epitaxy via digital alloy method.In the quantum well structure tensile AllnGaAs are used as barriers to partially compensate for the significant compressive strain in the wells,the strain compensation effects are confirmed by x-ray measurement.The photoluminescence spectra of the sample are dominated by the excitonic recombination peak in the whole temperature range.The thermal quenching,peak energy shift and line-width broadening of the PL spectra are analysed in detail,the mechanisms are discussed.
Directory of Open Access Journals (Sweden)
Ruilan Tian
2016-06-01
Full Text Available The coupled system of smooth and discontinuous absorber and beam bridge under moving loads is constructed in order to detect the effectiveness of smooth and discontinuous absorber. It is worth pointing out that the coupled system contains an irrational restoring force which is a barrier for conventional nonlinear techniques. Hence, the harmonic balance method and Fourier expansion are used to obtain the approximate solutions of the system. The first and the second kind of generalized complete elliptic integrals are introduced. Furthermore, using power flow approach, the performance of smooth and discontinuous absorber in vibration reduction is estimated through the input energy, the dissipated energy, and the damping efficiency. It is interesting that only depending on the value of the smoothness parameter, the efficiency parameter of vibration reduction is optimized. Therefore, smooth and discontinuous absorber can adapt itself to effectively reducing the amplitude of the vibration of the beam bridge, which provides an insight to the understanding of the applications of smooth and discontinuous oscillator in engineering and power flow characteristics in nonlinear system.
Skrinar, Matjaž
2012-01-01
This paper brings new insights into the implementation of a simplified computational model in the prediction of buckling load Pcr for slender beam-type structures with a transverse crack. From among several approaches discussed, two of them produced applicable results exhibiting considerably good agreement with those values from more precise and complex computational models. In the first approach, the critical load value is obtained from numerical solutions of analytically expressed character...
Directory of Open Access Journals (Sweden)
Krishna Lok Singh
2014-07-01
Full Text Available In this article, the delamination onset and growth behavior of double cantilever beam (DCB specimens has been presented. The modeling of a debonded region using master and slave surface technique for DCB specimens is done in ABAQUS CAE. The analysis of DCB specimens comprising of fatigue cyclic load has been done in ABAQUS. An onset and Paris delamination growth regimes are plotted. The growth regime being linear in log-log scale, the prediction of constants of this regime has been obtained using the polyfit command in the MATLAB environment. To obtain these constants has been explained in this article. Comparison of experimental and analytical results is shown for delamination growth. The strain energy release rate values for threshold and critical are indicated on the graphs. The number of cycles for delamination onset and growth has been tabulated for various load cases.Defence Science Journal, Vol. 64, No. 4, July 2014, pp. 400-405, DOI:http://dx.doi.org/10.14429/dsj.64.4069
Disinfection and reduction of organic load of sewage water by electron beam radiation
Maruthi, Y. Avasn; Das, N. Lakshmana; Hossain, Kaizar; Sarma, K. S. S.; Rawat, K. P.; Sabharwal, S.
2011-09-01
The efficacy of electron beam radiation for the disinfection and reduction of organic load of sewage water was assessed with ILU-6 Accelerator at Radiation Technology Development Division of the Bhabha Atomic Research Centre, Mumbai India. The current problem on environmental health in relation to water pollution insists for the safe disposal of sewage water. In general, sewage water comprises heterogeneous organic based chemicals as well as pathogens. EB treatment of the wastewater has found to be very effective in reducing the pathogens as well as organic load. EB dose of 1.5 kGy was sufficient for complete elimination of total coli forms. The experimental results elucidated the reduction of biological oxygen demand—BOD (35 and 51.7%) in both inlet and outlet sewage samples. Similarly reduction of chemical oxygen demand—COD was observed (37.54 and 52.32%) in both sewage samples with respect to increase in irradiation doses (0.45-6 kGy). The present study demonstrated the potential of ionizing radiation for disinfection of sewage and to increase the water quality of the wastewater by decreasing BOD and COD. So, the irradiation sewage water can find its application either in agriculture for irrigation, in industry for cooling purpose and some selected domestic purposes.
Directory of Open Access Journals (Sweden)
E. Mardani
2008-01-01
Full Text Available A prismatic beam made of a behaviorally nonlinear material was analyzed under a concentrated load moving with a known velocity on a nonlinear elastic foundation with a reaction the vibration equation of motion was derived using Hamilton principle and Euler Lagrange equation. The amplitude of vibration, circular frequency, bending moment, stress and deflection of the beam can be calculated by the presented solution. Considering the response of the beam, in the sense of its resonance, it was found that there is no critical velocity when the behavior of the beam and foundation material is assumed to be physically nonlinear and there are finite values for the deflection, stress and bending moment of the beam when
Motion compensator for holographic motion picture camera
Kurtz, R. L.
1973-01-01
When reference beam strikes target it undergoes Doppler shift dependent upon target velocity. To compensate, object beam is first reflected from rotating cylinder that revolves in direction opposite to target but at same speed. When beam strikes target it is returned to original frequency and is in phase with reference beam. Alternatively this motion compensator may act on reference beam.
Directory of Open Access Journals (Sweden)
Panatchai Chetchotisak
2015-09-01
Full Text Available Because of nonlinear strain distributions caused either by abrupt changes in geometry or in loading in deep beam, the approach for conventional beams is not applicable. Consequently, strut-and-tie model (STM has been applied as the most rational and simple method for strength prediction and design of reinforced concrete deep beams. A deep beam is idealized by the STM as a truss-like structure consisting of diagonal concrete struts and tension ties. There have been numerous works proposing the STMs for deep beams. However, uncertainty and complexity in shear strength computations of deep beams can be found in some STMs. Therefore, improvement of methods for predicting the shear strengths of deep beams are still needed. By means of a large experimental database of 406 deep beam test results covering a wide range of influencing parameters, several shapes and geometry of STM and six state-of-the-art formulation of the efficiency factors found in the design codes and literature, the new STMs for predicting the shear strength of simply supported reinforced concrete deep beams using multiple linear regression analysis is proposed in this paper. Furthermore, the regression diagnostics and the validation process are included in this study. Finally, two numerical examples are also provided for illustration.
DEFF Research Database (Denmark)
Bertheussen, Bård; Mustakallio, Panu; Kosonen, Risto;
2013-01-01
The impact of heat load strength and positioning on the indoor environment generated by diffuse ceiling air supply and chilled beam with radial swirl jet was studied and compared. An office room with two persons and a meeting room with six persons were simulated in a test room (4.5 x 3.95 x 3.5 m3...
Directory of Open Access Journals (Sweden)
Rezgar Shakeri
2014-01-01
Full Text Available Sound radiation from a beam resting on a viscoelastic foundation is analytically studied when it is subjected to a moving load. The topic could cover a range of applications such as submerged floating tunnels, buried pipelines, and railway tracks. Galerkin’s method is employed to obtain the transverse vibration of the beam. Based on the Rayleigh integral approach, acoustic pressure distribution around the beam is obtained in the time domain. In the second part of this paper, corresponding displacement and acoustic pressure are obtained by the use of the Rayleigh-Ritz approach in conjunction with the Laplace transform method and by the use of the Fourier transform, respectively. Durbin’s numerical Laplace transform inversion scheme is eventually employed to obtain dynamic responses. A parametric study is then carried out and influences of the design parameters as well as the loading conditions on the acoustic pressure field are investigated.
International Nuclear Information System (INIS)
Highlights: • RC shear deficient beams strengthened with NSM GFRP bars. • Both the load carrying capacity and ductility has been enhanced. • A finite element model is developed. • The model predicted the behavior of tested specimens. - Abstract: The aim of this investigation is to evaluate experimentally and numerically the cyclic loading response of reinforced concrete (RC) beams strengthened in shear with Glass Fiber Reinforced Polymer (GFRP) rods using the near surface mounted (NSM) technique. The experimental results indicated that the use of GFRP rods as NSM strengthening systems can significantly enhance the overall capacity and ductility of shear deficient RC members when subjected to cyclic loading. In particular, the increase in the load-carrying capacity of the strengthened specimens over the unstrengthened control specimen was in the range of 49–66%. Furthermore, the increase in the displacement over the control specimen ranged between 112% and 172%. A 3D finite element (FE) model was also developed to simulate the response of the tested specimens. The developed FE model integrates multiple simulation techniques, nonlinear material properties and corresponding constitutive laws. The models incorporate concrete cracking, yielding of steel reinforcement, bond–slip behavior between NSM reinforcement and adhesive material and between steel reinforcement and adjacent concrete material, respectively. The load–deflection response envelopes and the load–deflection hysteresis loops of the experimentally tested beams and those simulated by the FE models were compared. Good matching was observed between the predicted and measured results at all stages of cyclic loading
Institute of Scientific and Technical Information of China (English)
Mykolas DAUGEVI(C)IUS; Juozas VALIVONIS; Gediminas MAR(C)IUKAITIS
2012-01-01
This paper presents the results of an experimental research on reinforced concrete beams strengthened with an external carbon fibre reinforced polymer (CFRP) layer under long-term load action that lasted for 330 d.We describe the characteristics of deflection development of the beams strengthened with different additional anchorages of the external carbon fibre composite layer during the period of interest.The conducted experiments showed that the additional anchorage influences the slip of the extemal layer with respect to the strengthened element.Thus,concrete and carbon fibre composite interface stiffness decreases with a long-term load action.Therefore,the proposed method of analysis based on the built-up-bars theory can be used to estimate concrete and carbon fibre composite interface stiffness in the case of long-term load.
Makai, Janos P.
2016-02-01
The positioning of a plane specular sample to be measured or processed is an important requirement in many fields of research and industry. Where a sample is to be processed either by electromagnetic waves or a particle beam of higher numerical aperture the irradiance or the particle number over unit area is position and angle dependent. Where optical properties of a sample are to be measured, such as in spectrophotometry, these parameters can depend on the angle of incidence and on the value of the irradiance, i.e. on the angular and spatial position of the sample. In some cases parameters of many samples have to be compared among each other or to those of a standard, this also requires the highly accurate positioning of each sample to the same position. This paper describes a method that is suitable for high accuracy alignment of specular plane samples both angularly and spatially. It applies a double beam triangulation probe, where the second beam serves not only as a reference beam to compensate for any changes of the transmitting media and that of the laser but also doubles the sensitivity of the probe. The method does not compete with interferometric methods, it is required only in special applications, but provides an absolute uncertainty for spatial positioning in the sub-micrometer range and an angular one in the 0.0003° range. Furthermore, the accuracy is tunable by the parameters of the setup.
Arboleda-Monsalve, Luis G.; Zapata-Medina, David G.; Aristizabal-Ochoa, J. Darío
2008-03-01
The dynamic-stiffness matrix and load vector of a Timoshenko beam-column resting on a two-parameter elastic foundation with generalized end conditions are presented. The proposed model includes the frequency effects on the stiffness matrix and load vector as well as the coupling effects of: (1) bending and shear deformations along the member; (2) translational and rotational lumped masses at both ends; (3) translational and rotational masses uniformly distributed along its span; (3) axial load (tension or compression) applied at both ends; and (4) shear forces along the span induced by the applied axial load as the beam deforms according to the "modified shear equation" proposed by Timoshenko. The dynamic analyses of framed structures can be performed by including the effects of the imposed frequency ( ω>0) on the dynamic-stiffness matrix and load vector while the static and stability analyses can be carried out by making the frequency ω=0. The proposed model and corresponding dynamic-stiffness matrix and load vector represent a general solution capable to solve, just by using a single segment per element, the static, dynamic and stability analyses of any elastic framed structure made of prismatic beam-columns with semi-rigid connections resting on two-parameter elastic foundations. Analytical results indicate that the elastic behavior of framed structures made of beam-columns is frequency dependent and highly sensitive to the coupling effects just mentioned. Three comprehensive examples are presented to show the capacities and validity of the proposed method and the obtained results are compared with the finite element method and other analytical approaches.
Institute of Scientific and Technical Information of China (English)
糜晓波; 王文华; 唐永伟; 张少华
2012-01-01
Optimization problem for dispatch between local power generation and interruptible load(IL) resources when electricity shortage happens is addressed.Emphasis is given to the issue of how to determine the economic compensation in the IL programs,with which a consistent choice for the load interruption by power supply-side and demand-side can be realized and at the same time the optimal social welfare can be achieved.For this purpose,two compensation methods,namely the linear compensation and the nonlinear compensation,are developed.Numerical simulation shows that as compared with the linear compensation,the nonlinear compensation leads to a lower compensation price,which means that using the nonlinear compensation method,load management with optimal social welfare can be achieved by a relatively small amount of economic compensation.%针对供电紧张时地方电厂和可中断负荷资源之间的优化调度问题,重点研究了如何确定可中断负荷的经济补偿,使得供电侧和用户侧对于负荷中断量的选择能协调一致,并达到社会效益最优。设计了两种负荷中断补偿方法,即线性补偿和非线性补偿,并通过算例分析表明,与线性补偿相比,非线性补偿具有较低的单位补偿价格,即通过较小的经济补偿就能实现社会效益最优的负荷管理策略。
Directory of Open Access Journals (Sweden)
Wortmann Norbert
2011-05-01
Full Text Available Abstract Background The human spine is often exposed to mechanical load in vocational activities especially in combination with lifting, carrying and positioning of heavy objects. This also applies in particular to nursing activities with manual patient handling. In the present study a detailed investigation on the load of the lumbar spine during manual patient handling was performed. Methods For a total of 13 presumably endangering activities with transferring a patient, the body movements performed by healthcare workers were recorded and the exerted action forces were determined with regard to magnitude, direction and lateral distribution in the time course with a "measuring bed", a "measuring chair" and a "measuring floor". By the application of biomechanical model calculations the load on the lowest intervertebral disc of the lumbar spine (L5-S1 was determined considering the posture and action force data for every manual patient handling. Results The results of the investigations reveal the occurrence of high lumbar load during manual patient handling activities, especially in those cases, where awkward postures of the healthcare worker are combined with high action forces caused by the patient's mass. These findings were compared to suitable issues of corresponding investigations provided in the literature. Furthermore measurement-based characteristic values of lumbar load were derived for the use in statement procedures concerning the disease no. 2108 of the German list of occupational diseases. Conclusions To protect healthcare workers from mechanical overload and the risk of developing a disc-related disease, prevention measures should be compiled. Such measures could include the application of "back-fairer" nursing techniques and the use of "technical" and" small aids" to reduce the lumbar load during manual patient handling. Further studies, concerning these aspects, are necessary.
A more economical compensation method for unbalanced load%不平衡负载的一种更加经济的补偿方法
Institute of Scientific and Technical Information of China (English)
傅军栋; 喻勇; 黄来福
2015-01-01
For low-voltage distribution network unbalanced load loss reduction, we think of the capacitance compensation, which can improve the power factor of power grid and reduce the loss of power transformers and transmission lines, as well as improve the efficiency of power supply improvement and environment in the power supply system. Traditional methods simply calculate the admittance compensation value required by the load, then configure the appropriate capacitor;a relatively new kind of admittance calculation method is the balance component method. This paper puts forward a "Line Adjustment Act" drop loss compensation method to perform three phase load line regulation, which only adjusts the access phase of users’ meter box. A commutation strategy based on intelligent optimization algorithm is proposed, which does not require additional investment, and through a numerical example, the validity and effectiveness of this method are verified. Therefore, the"Line Adjustment Act"is a more simple and more economical method of reducing loss.%针对低压配电网不平衡负载降损的问题，会联想到电容补偿器，其在供电系统中起到提高电网的功率因数与降低供电变压器及输送线路的损耗，提高供电效率以及改善供电环境的作用。传统方法只需计算出负载所需要补偿的导纳值，然后配置相应的电容器，比较新的一种导纳值计算方法如平衡分量法。提出一种“线路调整法”的降损补偿方法，进行负荷三相平衡线路调整，仅需对用户集表箱的接入相做调整。提出一种基于优化算法的智能换相策略，不需要增加额外投资，通过算例分析验证了此方法的正确性和有效性。因此，“线路调整法”是一种更简单、更经济的降损方法。
对流量补偿电液负载模拟器的研究%Study on electro-hydraulic load simulator based on flow compensation method
Institute of Scientific and Technical Information of China (English)
安惠; 汪成文; 郝晓欣; 权龙
2015-01-01
针对多余力影响电液负载模拟器加载精度的问题，增加了流量补偿回路。由于运动的承载系统强迫负载模拟器跟随其运动产生多余力，而多余力是影响电液负载模拟器跟踪精度的主要因素。利用流量补偿速度回路、伺服阀力回路分别控制负载模拟器速度和输出力，从结构上实现力与速度的解耦，消除被测系统主运动对电液负载模拟器加载精度的影响。利用阀口压差对速度回路中的伺服阀流量进行修正，以消除压降对流量的影响从而提高流量补偿回路动态性能。基于PID控制建立系统数学模型并搭建物理仿真模型，通过理论分析和仿真结果分析证明该方案具有可行性。%To address the surplus force problem of electro-hydraulic load simulator (EHLS),a method adding a flow compensation circuit is developed in this paper.As the major factor affecting the tracking performance of EHLS,surplus force is mainly caused by loaded system’s active motion.Through adding the flow compensation velocity circuit,force and velocity are respectively controlled and well decoupled.Thus the influence of the actua-tor’s velocity on the loading force can be well eliminated.Utilizing the pressure difference at valve’s ports,the flow trough servo valve is modified.The flow of modified servo valve does not correspond to its pressure drop yet, which finally improve the dynamic performance of flow compensation circuit.System mathematical model and sim-ulation model are built based on PID control.Theoretical analysis and simulation results prove the feasibility of the method.
DEFF Research Database (Denmark)
Loh, P.; Tang, Y.; Blaabjerg, Frede;
2011-01-01
In this study, repetitive current controllers operating in either the mixed or stationary frame are proposed for high-precision reference tracking and disturbance rejection of power converters. Both controllers use a proportional-resonant regulator in the stationary frame for regulating...... the positive- and negative-sequence fundamental currents, which are known to directly influence the flow of active and reactive power in most energy conversion systems. Moreover, for the tracking or compensation of harmonics, the controllers include a repetitive control path in either the synchronous...... or stationary frame, whose inherent feedback and feedforward structure is proven to resemble a bank of resonant filters in either reference frames. Unlike other existing controllers, the proposed repetitive controllers function by introducing multiple resonant peaks at only those harmonic frequencies typically...
三相不平衡负载无功补偿方法的研究%Research on Reactive Compensation Method for Unbalanced Load
Institute of Scientific and Technical Information of China (English)
黄国栋; 杨仁刚; 冯小明
2011-01-01
In view of the hazards caused by three - phase unbalanced load, combined with the actual placement of the capacitor, using programming idea, the paper presents a new compensation algorithm for three - phase four - wire systems. The algorithm considers the minimization of power loss as its objective function, and the algorithm can make full use of existing capacitors to achieve optimal compensation effect. It builds an experimental platform with AT91RM9200 as the controller, analyses and simulates the experimental data. Experimental results show that the algorithm not only can compensate the power factor, but also can reduce the three - phase current unbalance, which prove the theoretical analysis. A better power quality and energy - saving can be obtained according to the algorithm.%针对三相不平衡负载对电力系统造成的危害,结合实际电容器的配置,利用规划的思想,本文推导出了三相四线制下新的补偿算法.该算法以有功损耗最小为目标函数,能够充分利用已有的电容器,达到最优的补偿效果.以AT91RM9200为控制器搭建了实验平台,并对实验数据进行分析和仿真,以验证该算法.实验的结果表明,这种算法既能够补偿功率因数,又能够降低三相电流的不平衡度,证明了理论推导的正确性.该方法提高了电能质量,达到了节能效果.
Gonzalez-Tinoco, Juan E.; Gomez-Rosas, Enrique R.; Guzmán-Olguín, Héctor; Khotiaintsev, Sergei; Zuñiga-Bravo, Miguel A.
2015-04-01
We present results of an ongoing study of structural health monitoring of concrete elements by means of arrays of telecommunications-grade optical fibers embedded in such elements. In this work, we show a possibility of using this technique for monitoring the transverse displacement of the reinforced concrete beams under flexural loading. We embedded a number of multimode silica-core/polymer-clad/polymer-coated optical fibers in a mold with preinstalled reinforcing steel bars and fresh concrete mix. Then the concrete was compacted and cured. Some optical fibers were broken during the fabrication process. The fiber survival rate varied with concrete grade, compacting technique and optical fiber type. The fibers that survived the fabrication process were employed for the monitoring. They were connected to the optical transmitter and receiver that formed a part of a larger measurement system. The system continuously measured the optical transmission of all optical fibers while the reinforced concrete beams were subjected to incremental transverse loading. We observed a quasi-linear decrease in optical transmission in all optical fibers of the array vs. the applied load and respective flexural displacement. Although the underlying phenomena that lead to such a variation in optical transmission are not clear yet, the observed behavior might be of interest for assessing the transverse displacement of the reinforced concrete beams under flexural loading.
International Nuclear Information System (INIS)
For materials selection of plasma-facing components in nuclear fusion devices it is necessary to determine threshold values of materials damage under short-time high heat fluxes in laboratory experiments. Plasma disruption loads were simulated with different nonmetallic candidate materials using Nd-YAG high power solid state lasers. The impinging energy density was varied between 0.2 and 20 MJ/m2 with pulse lengths tp ranging from 0.1 to 10 ms. Special experiments were carried out in situ in a scanning electron microscope coupled with a pulsed Nd-YAG laser and various analytical equipments. Thermal shock crack formation and propagation response, erosion behaviour and distribution of elements after successive thermal shock loading can be studied in situ with high lateral resolution inside a SEM. The dependence of damage initiation and propagation on the laser beam parameters such as pulse energy and number, spot size and pulse length was studied for fine grain graphites, nitride and carbide ceramics, CFC compound and coated materials. The threshold values for these structural damages were quantified using a heat flux parameter φabs√(tp). Detected damage parameters are 3D-erosion profiles, length and orientation distribution of cracks, redeposition rate, etc. Threshold values received by electron beam loads and by numerical calculations under comparable conditions are in approximate agreement with the laser load experimental results. It can be concluded that laser beam simulation represents a simple method for thermal shock testing. ((orig.))
Directory of Open Access Journals (Sweden)
Guibing Li
2014-05-01
Full Text Available Debonding failure is the main failure mode in flexurally strengthened reinforced concrete beams by externally bonded or near surface mounted fibre reinforced polymer (FRP composites. It is believed that FRP debonding will be initiated if the shear stress on the concrete-FRP interface reaches the tensile strength of concrete. However, it was found through experimental and analytical studies that the debonding mechanism of FRP composites has the potential of shear failure in combination with debonding failure. Moreover, the shear failure probably influences the debonding failure. Presently, there are very little experimental and analytical studies to investigate the influence of shear resistance of reinforced concrete (RC beam on FRP debonding failure. The current study investigates and analyzes the effect of shear resistance on FRP debonding failure based on test results. The analytical results show that the shear resistance of RC beam has a great effect on flexural debonding load-carrying capacity of FRP-strengthened RC beam. The influence of shear resistance on flexural debonding load-carrying capacity must be fully considered in flexural strengthening design of RC beams.
Directory of Open Access Journals (Sweden)
Marco Bögel
2013-01-01
Full Text Available Long acquisition times lead to image artifacts in thoracic C-arm CT. Motion blur caused by respiratory motion leads to decreased image quality in many clinical applications. We introduce an image-based method to estimate and compensate respiratory motion in C-arm CT based on diaphragm motion. In order to estimate respiratory motion, we track the contour of the diaphragm in the projection image sequence. Using a motion corrected triangulation approach on the diaphragm vertex, we are able to estimate a motion signal. The estimated motion signal is used to compensate for respiratory motion in the target region, for example, heart or lungs. First, we evaluated our approach in a simulation study using XCAT. As ground truth data was available, a quantitative evaluation was performed. We observed an improvement of about 14% using the structural similarity index. In a real phantom study, using the artiCHEST phantom, we investigated the visibility of bronchial tubes in a porcine lung. Compared to an uncompensated scan, the visibility of bronchial structures is improved drastically. Preliminary results indicate that this kind of motion compensation can deliver a first step in reconstruction image quality improvement. Compared to ground truth data, image quality is still considerably reduced.
Schäfer, D.; Lin, M.; Rao, P. P.; Loffroy, R.; Liapi, E.; Noordhoek, N.; Eshuis, P.; Radaelli, A.; Grass, M.; Geschwind, J.-F. H.
2012-03-01
C-arm based tomographic 3D imaging is applied in an increasing number of minimal invasive procedures. Due to the limited acquisition speed for a complete projection data set required for tomographic reconstruction, breathing motion is a potential source of artifacts. This is the case for patients who cannot comply breathing commands (e.g. due to anesthesia). Intra-scan motion estimation and compensation is required. Here, a scheme for projection based local breathing motion estimation is combined with an anatomy adapted interpolation strategy and subsequent motion compensated filtered back projection. The breathing motion vector is measured as a displacement vector on the projections of a tomographic short scan acquisition using the diaphragm as a landmark. Scaling of the displacement to the acquisition iso-center and anatomy adapted volumetric motion vector field interpolation delivers a 3D motion vector per voxel. Motion compensated filtered back projection incorporates this motion vector field in the image reconstruction process. This approach is applied in animal experiments on a flat panel C-arm system delivering improved image quality (lower artifact levels, improved tumor delineation) in 3D liver tumor imaging.
Lynch, P. A.; Advanced Light Source
2008-01-01
Scanning white beam X-ray microdiffraction has been used to study the heterogeneous grain deformation in a polycrystalline Mg alloy (MgAZ31). The high spatial resolution achieved on beamline 7.3.3 at the Advanced Light Source provides a unique method to measure the elastic strain and orientation of single grains as a function of applied load. To carry out in-situ measurements a light weight (~;;0.5kg) tensile stage, capable of providing uniaxial loads of up to 600kg, was designed to collect d...
Yusuf Yesilce
2012-01-01
In the existing reports regarding free and forced vibrations of the beams, most of them studied a uniform beam carrying various concentrated elements using Bernoulli-Euler Beam Theory (BET) but without axial force. The purpose of this paper is to utilize the numerical assembly technique to determine the exact frequency-response amplitudes of the axially-loaded Timoshenko multi-span beam carrying a number of various concentrated elements (including point masses, rotary inertias, linear springs...
A Novel Friction Compensation Method Using Positive Torque Load%使用主动阻力矩的摩擦补偿新方法
Institute of Scientific and Technical Information of China (English)
庄文许; 杨必武; 马大为; 孟庆爱; 张秀维
2012-01-01
Aiming at phenomena of Vibrations and stick-slip motions caused by friction in the rotating servosystem, a novel friction compensation method using positive torque load was proposed. The principle of which was, while the servosystem operated at low speed, by giving an additional torque load to compensate the system and improving gain factor of the servosystem controller, the sensitivity was reduced between the regulated output and friction torque load of the servo system. By using sensitivity equations and the stability law, this method was proved to be efficient. Based on the method, a compensation system, which used a magnetorheological detent as a core was designed. And it was used in a typical position control system, and a simulation model was established. The simulation results show that the peak value of the tracking error undulation under a given disturbance is reduced from 0.45° to 0. 025° by increasing the value of the positive torque from zero to as big as eight times of the given disturbance. The method was high real-time, and the disadvantage of system vibrating when using a high gain controller was conquered. Both theoretical analysis and simulation results demonstrate that the phenomena of friction stick-slip motions and vibrations are rejected significantly by the compensation system.%针对旋转伺服系统中摩擦造成低速爬行和振荡现象,提出使用主动阻力矩进行摩擦补偿的方法,其原理是当伺服系统低速运行时,通过补偿系统主动增加负载阻力矩,并提高伺服系统控制器增益系数来降低系统输出调节量对摩擦力矩的灵敏度,应用灵敏度方程和稳定性理论证明了该方法的有效性.基于该方法设计了以磁流变制动器为核心的补偿系统,并将其应用于典型位置控制系统,建立仿真模型,仿真结果显示,在给定干扰力矩作用下,从零增加主动阻力矩至与干扰力矩数值比达到8时,跟踪误差波动幅值从0.45°降低至0
International Nuclear Information System (INIS)
A time-varying state-space control model was presented and used to predict the functions required to cure the injection voltage transients. We discuss a novel method to calculate the feedforward functions. Simulation results are shown to validate the method
Plasma-assisted molecular beam epitaxy of strain-compensated a-plane InGaN/AlGaN superlattices
International Nuclear Information System (INIS)
Strain-compensated InGaN/AlGaN structures can enable the growth of thick layers of InGaN epitaxial films far beyond the critical thickness for InGaN grown pseudomorphically to GaN. In this paper, we demonstrate the epitaxial growth of high-quality strain-compensated a-plane In0.12Ga0.88N/Al0.19Ga0.81N superlattices up to 5 times thicker than the critical thickness on free-standing a-plane GaN substrates by plasma-assisted molecular beam epitaxy (PA-MBE). The superlattices consist of 50 to 200 periods of 10 nm thick In0.12Ga0.88N and 6 nm thick Al0.19Ga0.81N layers. The structures are characterized using a double crystal X-ray diffractometer, asymmetric reciprocal space mapping, and atomic force microscopy. We use X-ray diffraction to determine the strain, composition, degree of relaxation, and superlattice period of our samples. The structural characteristics of periodic structures containing from 50 to 200 periods are compared to single layer, uncompensated In0.12Ga0.88N films. A 100 period structure exhibited only 15% relaxation compared to 69% relaxation for the bulk In0.12Ga0.88N film grown with the same total InGaN thickness but without strain-compensating layers. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Directory of Open Access Journals (Sweden)
Bin Zhen
2014-01-01
Full Text Available Critical velocities are investigated for an infinite Timoshenko beam resting on a Winkler-type elastic foundation subjected to a harmonic moving load. The determination of critical velocities ultimately comes down to discrimination of the existence of multiple real roots of an algebraic equation with real coefficients of the 4th degree, which can be solved by employing Descartes sign method and complete discrimination system for polynomials. Numerical calculations for the European high-speed rail show that there are at most four critical velocities for an infinite Timoshenko beam, which is very different from those gained by others. Furthermore, the shear wave velocity must be the critical velocity, but the longitudinal wave velocity is not possible under certain conditions. Further numerical simulations indicate that all critical velocities are limited to be less than the longitudinal wave velocity no matter how large the foundation stiffness is or how high the loading frequency is. Additionally, our study suggests that the maximum value of one group velocity of waves in Timoshenko beam should be one “dangerous” velocity for the moving load in launching process, which has never been referred to in previous work.
International Nuclear Information System (INIS)
Combined heat and power (CHP) plants dominate the heating market in China. With the ongoing energy structure reformation and increasing environmental concerns, we propose gas-fired boilers to be deployed in underperforming heating substations of heating networks for peak load compensation, in order to improve both energy efficiency and environmental sustainability. However, due to the relatively high price of gas, techno-economic analysis is required for evaluating different combined heating scenarios, characterized by basic heat load ratio (β). Therefore, we employ the dynamic economics and annual cost method to develop a techno-economic model for computing the net heating cost of the system, considering the current state of the art of cogeneration systems in China. The net heating cost is defined as the investment costs and operations costs of the system subtracted by revenues from power generation. We demonstrate the model in a real-life combined heating system of Daqing, China. The results show that the minimum net heating cost can be realized at β=0.75 with a cost reduction of 16.8% compared to coal heating alone. Since fuel cost is the dominating factor, sensitivity analyses on coal and gas prices are discussed subsequently. - Highlights: ► Combined heating systems comply with the energy structure reformation in China. ► We consider the current state of the art of cogeneration systems in China. ► Combined heating systems can be economically more feasible and sustainable. ► The net heating cost of a combined heating system is more sensitive to coal price. ► The optimal basic heat load ratio is more easily influenced by gas price.
An atomic beam source for fast loading of a magneto-optical trap under high vacuum
DEFF Research Database (Denmark)
McDowall, P.D.; Hilliard, Andrew; Grünzweig, T.;
2012-01-01
We report on a directional atomic beam created using an alkali metal dispenser and a nozzle. By applying a high current (15 A) pulse to the dispenser at room temperature we can rapidly heat it to a temperature at which it starts dispensing, avoiding the need for preheating. The atomic beam produced...
Load-to-failure bending test of wood composite beams connected by gang nail
Directory of Open Access Journals (Sweden)
A.V. Karelskiy
2015-03-01
Full Text Available The results of a bending test of wood composite beams connected by gang nail are presented in this paper. Two types of wood composite beams fracture were observed: brittle and ductile. In addition, a numerical model of wood composite beams was produced and the results of the numerical investigations were analyzed. Compliance of connection «gang nail – wood» was considered by means of input elements with a reduced modulus of elasticity in the numerical model. Then the theoretical and experimental results of stress and strain state of a composite beam with gang nail were compared. The conclusion was made about the efficiency of gang nail application for increased shear resistance of wood composite structures not only for reinforcement but also for production of new beam structures.
Institute of Scientific and Technical Information of China (English)
邵俊鹏; 李建英; 王仲文; 韩桂华
2009-01-01
针对电液负载模拟器存在多余力,且多余力严重影响加载精确度的问题,同时为了提高加载系统的控制性能,介绍了电液负载模拟器的工作原理,对舵机系统、加载系统分别进行建模,建立整个电液负载模拟器系统的控制模型.设计了结构补偿环节,提出电液负载模拟器多余力抑制的控制方案,从理论上结构补偿环节可以实现对系统全部补偿和抑制多余力.对采用结构补偿环节前后的模型进行仿真分析和实验研究,结果表明采用结构补偿环节能使多余力大幅度减小, 动态加载精确度明显提高,验证了控制方案的正确性和有效性.%Aiming at the superfluous force existing in the electro-hydraulic load simulator and the problem of the superfluous force influencing the load precision seriously, in order to improve the control performance of the load system, the work principle of the electro-hydraulic load simulator was introduced, and after building the control model of the rudder system and the load system, the whole electro-hydraulic load simulator control model was built. The structure compensation unit was designed and the control scheme of eliminating the superfluous force of the electro-hydraulic load simulator was proposed. The structure compensation unit could compensate the whole system entirely and could eliminate the superfluous force well theoretically. The model with the structure compensation unit and the model without the structure compensation unit were studied by simulation and experiment. The results indicate that the structure compensation unit can reduce the superfluous force greatly, and indicate that the dynamic load precision is improved obviously. The study of simulation and experiment verifies the efficiency and correctness of the control scheme.
Flexural Capacity of Reinforced Concrete Beams Strengthened Using GFRP Sheet after Fatigue Loading
Djamaluddin, Rudy
2015-01-01
Fiber reinforced polymer (FRP) has been applied not only for the simple structures but also for the advanced structures such as bridges or highway bridges. In case of bridges or highway bridges, the structures experience not only static loadings but also fatigue loadings that may limited the serviceability of the bridge structures. In order to extend of the application of FRP on the such bridge structures, the flexural capacity due to fatigue loading should be clarified. Glass composed FRP sh...
Micromotion Compensation and Photoionization of Ions in a Linear Trap
Institute of Scientific and Technical Information of China (English)
XIE Yi; ZHOU Fei; CHEN Liang; WAN Wei; FENG Mang
2011-01-01
@@ e confinement of ions in an electromagnetic trap is a prerequisite of sideband cooling and quantum information processing.For a string of ions in a linear ion trap,we report our recent efforts of compensating for micromotion of the ions by three methods,which yields narrower fluorescence spectra and lower temperature.We also achieve a photoionization scheme that loads the ions deterministically into the linear trap from an atomic beam.%The stable confinement of ions in an electromagnetic trap is a prerequisite of sideband cooling and quantum information processing. For a string of ions in a linear ion trap, we report our recent efforts of compensating for micromotion of the ions by three methods, which yields narrower fluorescence spectra and lower temperature. We also achieve a photoionization scheme that loads the ions deterministically into the linear trap from an atomic beam.
Dung, Cao Vu; Sasaki, Eiichi
2016-04-27
Polyvinylidene Flouride (PVDF) is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental "stress-averaging" mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the "stress-averaging" mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam's modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor's output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading.
Directory of Open Access Journals (Sweden)
Shahrul Niza Mokhatar
2013-12-01
Full Text Available In this paper, a fully Lagrangian method namely as Smoothed Particle Hydrodynamics (SPH has been utilized in order to simulate the response of reinforced concrete beam subjected to low velocity impact loading. Models based on this method are proposed to capture an important failure mechanism on compression and tension of the beam elements under dynamic (impact loading condition. Pressure dependant criterion known as Drucker-Prager (DP with a new Plane-Cap (PC yield surface were employed to concrete, and (Von-Mises criterion was applied for steel reinforcement. The constitutive equation of PC model is employed on compression, while, orthotropic constitutive equation due to the damage effect is considered on tension. Meanwhile, Dynamic Increase Factor (DIF was defined separately for the effect of strain rate (SR on the concrete and steel reinforcement. Shear cracking, bending cracking and compressive behavior of the beam were evaluated by using displacement-time histories and overall failure mode. Then, the applicability and efficiency of the proposed models were validated with experimental tests through numerical simulations with different velocity (height of drop-mass.
Directory of Open Access Journals (Sweden)
Husain M. Husain
2013-05-01
Full Text Available In this work a program is developed to carry out the nonlinear analysis (material nonlinearity of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. are examined by the developed computer program to reach a certain analytical approach of the design and analysis of such beams because there is no available restrictions or recommendations covering this material in the codes. The program uses the finite element analysis by dividing the beams into isoparametric 20-noded brick elements. The results obtained are good in comparison with experimental results.
Husain M. Husain; Nazar K. Oukaili
2013-01-01
In this work a program is developed to carry out the nonlinear analysis (material nonlinearity) of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP) instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. a...
Foster, W Kyle; Osei, Ernest; Barnett, Rob
2015-01-08
The aim of this study is to provide guidelines for the selection of external-beam radiation therapy target margins to compensate for target motion in the lung during treatment planning. A convolution model was employed to predict the effect of target motion on the delivered dose distribution. The accuracy of the model was confirmed with radiochromic film measurements in both static and dynamic phantom modes. 502 unique patient breathing traces were recorded and used to simulate the effect of target motion on a dose distribution. A 1D probability density function (PDF) representing the position of the target throughout the breathing cycle was generated from each breathing trace obtained during 4D CT. Changes in the target D95 (the minimum dose received by 95% of the treatment target) due to target motion were analyzed and shown to correlate with the standard deviation of the PDF. Furthermore, the amount of target D95 recovered per millimeter of increased field width was also shown to correlate with the standard deviation of the PDF. The sensitivity of changes in dose coverage with respect to target size was also determined. Margin selection recommendations that can be used to compensate for loss of target D95 were generated based on the simulation results. These results are discussed in the context of clinical plans. We conclude that, for PDF standard deviations less than 0.4 cm with target sizes greater than 5 cm, little or no additional margins are required. Targets which are smaller than 5 cm with PDF standard deviations larger than 0.4 cm are most susceptible to loss of coverage. The largest additional required margin in this study was determined to be 8 mm.
Kaucikas, M.; Warren, M.; Michailovas, A.; Antanavicius, R.; van Thor, J. J.
2013-02-01
This paper describes the investigation of an optical parametric oscillator (OPO) set-up based on two beta barium borate (BBO) crystals, where the interplay between the crystal orientations, cut angles and air dispersion substantially influenced the OPO performance, and especially the angular spectrum of the output beam. Theory suggests that if two BBO crystals are used in this type of design, they should be of different cuts. This paper aims to provide an experimental manifestation of this fact. Furthermore, it has been shown that air dispersion produces similar effects and should be taken into account. An x-ray crystallographic indexing of the crystals was performed as an independent test of the above conclusions.
Yamamoto, M.; Nomura, M.; Shimada, T.; Tamura, F.; Hara, K.; Hasegawa, K.; Ohmori, C.; Toda, M.; Yoshii, M.; Schnase, A.
2016-11-01
An rf cavity in the J-PARC RCS not only covers the frequency range of a fundamental acceleration pattern but also generates multi-harmonic rf voltage because it has a broadband impedance. However, analyzing the vacuum tube operation in the case of multi-harmonics is very complicated because many variables must be solved in a self-consistent manner. We developed a method to analyze the vacuum tube operation using a well-known formula and which includes the dependence on anode current for some variables. The calculation method is verified with beam tests, and the results indicate that it is efficient under condition of multi-harmonics with a heavy beam loading effect.
Saedjalil, N.; Mehrangiz, M.; Jafari, S.; Ghasemizad, A.
2016-06-01
In this paper, the interaction of a self-focused laser beam with a DT fusion target in a plasma-loaded cone-guided ICF scheme has been presented. We propose here to merge a plasma-loaded cone with the precompressed DT target in order to strongly focus the incident laser beam on the core to improve the fusion gain. The WKB approximation is used to derive a differential equation that governs the evolution of beamwidth of the incident laser beam with the distance of propagation in the plasma medium. The effects of initial plasma and laser parameters, such as initial plasma electron temperature, initial radius of the laser beam, initial laser beam intensity and plasma density, on self-focusing and defocusing of the Gaussian laser beam have been studied. Numerical results indicate that with increasing the plasma frequency (or plasma density) in the cone, the laser beam will be self-focused noticeably, while for a thinner laser beam (with small radius), it will diverge as propagate in the cone. By evaluating the energy deposition of the relativistic electron ignitors in the fuel, the importance of electron transportation in the cone-attached shell was demonstrated. Moreover, by lessening the least energy needed for ignition, the electrons coupling with the pellet enhances. Therefore, it increases the fusion efficiency. In this scheme, with employing a plasma-loaded cone, the fusion process improves without needing an ultrahigh-intensity laser beam in a conventional ICF.
Indian Academy of Sciences (India)
S Rajagopal; S Prabavathy
2014-10-01
Reinforced concrete structures beam-column joints are the most critical regions in seismic prone areas. Proper reinforcement anchorage is essential to enhance the performance of the joints. An attempt has been made to appraise the performance of the anchorages and joints. The anchorages are detailed as per ACI-352 (mechanical anchorages), ACI-318 (conventional bent hooks) and IS-456 (conventional full anchorage). The joints are detailed without confinement in group-I and with additional X-cross bar in group-II. To assess the seismic performance, the specimens are assembled into two groups of three specimens each and were tested under reversal loading, The specimen with T-type mechanical anchorage (Headed bar) and T-type mechanical anchorage combination with X-cross bar exhibited significant improvement in seismic performance: load-displacement capacity, displacement ductility, stiffness degradation, controlled crack capacity in the joint shear panel and also reduced congestion of reinforcement in joint core.
Institute of Scientific and Technical Information of China (English)
LI LI
2010-01-01
@@ China's National People's Congress (NPC), the top legislature, recently adopted amendments to the Law on State Compensation, granting citizens greater power to obtain compensation when their rights are violated by the state.
Large deflection analysis of cantilever beam under end point and distributed load
DEFF Research Database (Denmark)
Kimiaeifar, Amin; Tolou, N; Barari, Amin;
2014-01-01
requires numerical solution of simultaneous equations which is a significant drawback for optimization or reliability analysis. This paper is motivated to overcome these shortcomings by presenting an analytical solution for the large deflection analysis of a cantilever beam under free end point and uniform...
Dung, Cao Vu; Sasaki, Eiichi
2016-01-01
Polyvinylidene Flouride (PVDF) is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental “stress-averaging” mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the “stress-averaging” mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam’s modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor’s output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading. PMID:27128919
Microsecond plasma opening switch experiments on Hawk with an e-beam diode load
International Nuclear Information System (INIS)
The Hawk generator is used in plasma opening switch (POS) experiments in the 1-μs conduction time regime to study long conduction time switch physics. Peak load powers of 0.7 TW with 55 kJ delivered to the diode--20% energy efficiency--were achieved with a POS. The data indicate that above a critical load impedance the final switch gap size is limited to about 3 mm. This limits the voltage. Maximum load power is obtained at this critical impedance. Increasing the cathode magnetic field--by conducting more current or by decreasing the cathode radius-allows the fixed-gap POS to remain insulated at a higher voltage. Peak load voltages up to 2 MV were achieved with a 2.5 cm diam cathode, a factor of 2.8 higher than the Marx voltage. Load powers were up to 70% higher with a plasma-filled diode (PFD) used in conjunction with the POS for short POS conduction times. The switch gap may be larger (> 3mm) on these short conduction PFD shots
Institute of Scientific and Technical Information of China (English)
乐南更; 彭天好; 张川; 许军; 王光洪
2012-01-01
分析变转速泵控马达调速系统转速降落的主要原因,指出系统泄漏和电机机械特性均能引起转速降落,推导出转速降落补偿系数表达式,建立了恒负载时变转速泵控马达调速系统转速降落补偿方法.实验结果表明:在恒负载时,采用所提出的补偿方法能够很好地实现转速降落补偿.%The reasons of motor speed loss in variable-speed pump-control-motor governing system were analyzed. It was pointed out that system leakage and electromotor mechanical properties were the reasons. Speed drop compensation coefficient expression was derived, and the compensation method under constant load in variable-speed pump-control-motor governing system was built. The experiment results show that using this compensation method, motor speed loss in constant load can be compensated.
Helicopter Rotor Load Prediction Using a Geometrically Exact Beam with Multicomponent Model
DEFF Research Database (Denmark)
Lee, Hyun-Ku; Viswamurthy, S.R.; Park, Sang Chul;
2010-01-01
In this paper, an accurate structural dynamic analysis was developed for a helicopter rotor system including rotor control components, which was coupled to various aerodynamic and wake models in order to predict an aeroelastic response and the loads acting on the rotor. Its blade analysis was based...
Institute of Scientific and Technical Information of China (English)
李瑞; 王明艳
2013-01-01
Extra torque existing in the motor drive load simulator influences the load precision and system stability. Aiming at the problem,based on the work principle and structure,the model of the load system was built and the structure compensation unit was designed. The limitations of the conventional compensation methods were analyzed,and an improved compensation method of structure invariance was proposed. The compound control method was used to design the entire control system. The simulation results indicate using the method,the extra torque can be reduced greatly. It has some feasibility in engineering.% 电动负载模拟器存在多余力矩，且严重影响加载精度和系统的稳定性。针对此问题，在分析加载系统基本结构和原理的基础上，建立加载系统模型，设计结构补偿环节；分析常规补偿方法的局限性，提出改进的结构不变性补偿方法，并用复合控制方法来设计控制系统。仿真结果表明：此方法能够大幅度消除多余力矩，且在工程中有一定的可行性。
Directory of Open Access Journals (Sweden)
Ping Lou
2008-01-01
Full Text Available In the finite element method, there are shortcomings using the conventional formulae to calculate the sectional forces, i.e., the bending moment and the shear force, at any cross-section of Bernoulli-Euler beam under dynamic loads. This paper presents some new finite-element formulae overcoming the shortcomings of the conventional ones to calculate the sectional forces at any cross-section of a Bernoulli-Euler beam on continuously viscoelastic foundation subjected to concentrated moving loads. The proposed formulae can easily degenerate into the formulae for calculating the sectional forces of a simply supported or a continuous Bernoulli-Euler beam subjected to concentrated moving loads, and into the formulae for calculating the sectional forces of a Bernoulli-Euler beam on Winkler foundation under static loads. Five numerical examples including static and dynamic analyses are chosen to illustrate the application of the proposed formulae. Numerical results show: (1 compared with the conventional formulae, the proposed formulae can improve the calculation accuracy of the sectional forces of beam; (2 one should use the proposed formulae, not the conventional formulae, to calculate the sectional forces at any cross-section in Bernoulli-Euler beam.
Flexural analysis of deep beam subjected to parabolic load using refined shear deformation theory
Ghugal Y. M.; Dahake A. D.
2012-01-01
A trigonometric shear deformation theory for flexure of thick or deep beams, taking into account transverse shear deformation effects, is developed. The number of variables in the present theory is same as that in the first order shear deformation theory. The sinusoidal function is used in displacement field in terms of thickness coordinate to represent the shear deformation effects. The noteworthy feature of this theory is that the transverse shear stresses can be obtained directly from the ...
Beam loading in the bubble regime in plasmas with hollow channels
Golovanov, A A; Thomas, J; Pukhov, A
2016-01-01
Based on the already existing analytical theory of the strongly-nonlinear wakefield (which is called "bubble") in transversely inhomogeneous plasmas, we study particular behavior of non-loaded (empty) bubbles and bubbles with accelerated bunches. We obtain an analytical expression for the shape of a non-loaded bubble in a general case and verify it with particle-in-cell (PIC) simulations. We derive a method of calculation of the acceleration efficiency for arbitrary accelerated bunches. The influence of flat-top electron bunches on the shape of a bubble is studied. It is also shown that it is possible to achieve acceleration in a homogeneous longitudinal electric field by the adjustment of the longitudinal density profile of the accelerated electron bunch. The predictions of the model are verified by 3D PIC simulations and are in a good agreement with them.
Impact And Explosive Loads On Concrete Buildings Using Shell And Beam Type Elements
Bermejo Castro, Mario; Goicolea Ruigómez, José María; Gabaldón Castillo, Felipe; Santos Yanguas, Anastasio Pedro
2011-01-01
The threat of impact or explosive loads is regrettably a scenario to be taken into account in the design of lifeline or critical civilian buildings. These are often made of concrete and not specifically designed for military threats. Numerical simulation of such cases may be undertaken with the aid of state of the art explicit dynamic codes, however several difficult challenges are inherent to such models: the material modeling for the concrete anisotropic failure, consideration of reinforcem...
Seismic Behavor of RC Beam-Column Joint with Additional Bars under Cyclic Loading
Institute of Scientific and Technical Information of China (English)
LU Xilin; Tonny H.URUKAP; LI Sen
2011-01-01
The behavior of Beam-Column Joints in moment resisting frame structures are susceptible to damage caused by seismic effects due to poor performance of the joint. A good number of researches were carried out to understand the complex mechanism of RC joints which are considered in seismic design code practices presently adopted. The traditional construction detailing of transverse reinforcement have shown serious joint failure.This paper introduces a new design philosophy involving the use of additional diagonal bars within the joint particularly suitable for low to medium seismic effects in earthquake zones throughout the world. In lieu to this study, ten (10) full-scale interior beam-column specimens were constructed with various additional reinforcement details and configurations as will be discussed in the later. The experiment provided adequate results to proof the idea of additional bars as suitable approach in reinforced concrete structures where earthquake is eminent. While compared with overall cracking observation during the test, the specimen with additional bars (diagonal and straight) had shown few cracks on the column than the ones without. Furthermore, concrete confinement is certainly an important design method as recommended by certain international codes.
Directory of Open Access Journals (Sweden)
Cao Vu Dung
2016-04-01
Full Text Available Polyvinylidene Flouride (PVDF is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental “stress-averaging” mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the “stress-averaging” mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam’s modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor’s output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading.
International Nuclear Information System (INIS)
The increasing world energy needs lead to strong efforts in today's energy R and D trying to open up new energy resources. One possible option to access energy in large scale power plants is to use the process of nuclear fusion to generate heat and, from that, electricity with conventional steam turbine technology. However, the realisation is technologically and scientifically very challenging. The heat fluxes that load the inner walls of a fusion device, especially the most severely loaded part, the divertor, are one of the issues currently being under investigation. A distinction is made between steady state heat loads (SSHLs) that are continuously active during operation and transient heat loads (THLs) that are superimposed short-time events. The potentially most harmful THLs during normal operation are type I Edge Localised Modes (ELMs). They are estimated to have a power density of 1 - 10 GWm-2 for 0.2 - 0.5 ms duration in the upcoming next step fusion experiment ITER. Because of high pulse repetition frequency more than 106 ELM events are expected during the foreseen lifetime of divertor components. However, only data regarding behaviour of materials for a low number of pulses (typically 100 - 1000) exists. This work describes the development of a procedure to simulate THLs at high repetition frequency using an electron beam facility and the tests done on tungsten and carbon-based (carbon fibre composite, CFC) plasma facing materials. The developed procedure uses a pulse frequency of 25 Hz, hence actively cooled components are necessary and were designed. A novel electron beam guidance procedure, called circular loading method, was a result of the developmental process. It was used for all later tests because it provides a stabilisation of the applied power density against test parameter fluctuations (e.g. vacuum quality). The electron beam guidance is flexible enough to provide a SSHL pattern during the interpulse time (between two successive THLs
Sederberg, S.; Elezzabi, A. Y.
2015-10-01
Silicon-loaded nanoplasmonic waveguides were integrated onto a micron-scale characterization beam to allow for accurate and efficient nonlinear optical characterization. The waveguides consist of a 95 nm × 340 nm silicon core that is capped by a 60 nm thick gold film. The characterization beam is formed by precision cleaving one waveguide end facet and by deep silicon etching the substrate area adjacent to the other end facet. This configuration allows input radiation to be coupled directly to the waveguides using a microscope objective and output radiation to be out-coupled with a lensed single-mode optical fiber. The fabrication steps are characterized via scanning electron microscopy at various points throughout the process. The fabricated devices are optically characterized using an ultrafast nonlinear pump-probe time-domain spectroscopy setup. Ultrafast all-optical modulation is measured in the waveguides on two timescales: τ1 = 1.98 ± 0.40 ps and τ2 = 17.9 ± 6.8 ps.
Distortional solutions for loaded semi-discretized thin-walled beams
DEFF Research Database (Denmark)
Andreassen, Michael Joachim; Jönsson, Jeppe
2012-01-01
distortional displacement fields which decouple the reduced order differential equations. In this process the cross section is discretized into finite cross-section elements, and the natural distortional modes as well as the related axial variations are found as solutions to the established coupled fourth......For thin-walled beams, the classic theory for flexural and torsional analysis of open and closed cross-sections can be generalized by including distortional displacements. In a companion paper it is shown that using a novel semi-discretization process, it is possible to determine specific...... order homogeneous differential equations of GBT.In this paper the non-homogeneous distortional differential equations of GBT are formulated using this novel semi-discretization process. Transforming these non-homogeneous distortional differential equations into the natural eigenmode space by using...
Institute of Scientific and Technical Information of China (English)
辛业春; 李国庆; 王朝斌
2014-01-01
A static synchronous compensator (STATCOM) is used into distribution grid for compensating reactive power and three- phase unbalance load for the distribution grid. According to analyzing the positive sequence equivalent circuit and negative sequence equivalent circuit under the three-phase unbalance load of distribution grid, using the symmetrical component method and superposition principle, a new cascade loop control strategy of positive sequence current and negative sequence current is proposed. Usingδ-θ control, the positive sequence loop compensates reactive power of distribution grid and maintains stability of STATCOM DC voltage. Usingφ-θ control in the negative sequence loop can make STATCOM compensate negative-sequence current caused by three-phase load unbalance and keep distribution grid side three-phase load balanced. Simulation and experiment results are presented to verify the validity of the proposed control strategy. This work is supported by National Natural Science Foundation of China (No. 51377016).%将静止同步补偿器（Static Synchronous Compensator,STATCOM）并入电网来补偿无功功率和配电网三相负荷不平衡。通过对称分量法和叠加原理，对配电网三相负荷不平衡情况下正序、负序等效电路进行分析，提出一种新的正、负序补偿电流叠加补偿控制方法。正序控制环采用δ-θ控制，实现配电网无功功率补偿和保持STATCOM直流侧电压稳定；负序控制环采用φ-θ控制，实现STATCOM补偿三相负荷不平衡产生的负序电流，使电网侧三相负荷保持平衡。仿真和实验结果表明，该方法可以有效地补偿电网无功功率和三相负荷不平衡。
International Nuclear Information System (INIS)
ITER relevant thermal shock loads have been performed in the electron beam facility, JUDITH. Dynamic erosion processes of fine grain graphite, carbon fiber composite (CFC) and W-1%La2O3 were observed by optical diagnostics. Collective small particle release which may correspond to erosion of graphite binder phase was observed at 2 GW/m2 in graphite, whereas, distinguished particle release was observed at the same power density in CFC. The distinguished particle release was concluded to be due to brittle destruction of overheated PAN fibers which has lower thermal conductivity in vertical direction. Most particles released from W-1%La2O3 were appeared to be droplets splashed from the molten surface. The contribution of brittle destruction in W-1%La2O3 was not clearly observed in this particular thermal shock loads. Release of tungsten atoms and WO molecules was not observed by emission spectrometer even at high power density, 1.1 GW/m2 which caused melting of the surfaces, however, release of LaO molecules was detected even at lower power density, 0.6 GW/m2 where and the surface did not show significant modification. (author)
Crab Compensation for LHC Beams
Calaga, R; Tomás, R; Zimmermann, F
2008-01-01
An R&D program to establish a road map for the installation of crab cavities in the LHC is rapidly advancing. Both local and global crab schemes are under investigation to develop cavities that will be compatible with the LHC optics and meet the aperture requirements. Space and aperture constraints to accommodate a prototype crab cavity in the LHC along with related optics issues are presented. The design of a prototype $TM_{110}$ cavity and pertinent RF requirements including impedance estimates and damping are discussed.
Adaptive Motion Compensation in Radiotherapy
Murphy, Martin J
2011-01-01
External-beam radiotherapy has long been challenged by the simple fact that patients can (and do) move during the delivery of radiation. Recent advances in imaging and beam delivery technologies have made the solution--adapting delivery to natural movement--a practical reality. Adaptive Motion Compensation in Radiotherapy provides the first detailed treatment of online interventional techniques for motion compensation radiotherapy. This authoritative book discusses: Each of the contributing elements of a motion-adaptive system, including target detection and tracking, beam adaptation, and pati
International Nuclear Information System (INIS)
The way of modeling the damping phenomenon in nonlinear time history analysis is still an opened question and remains a motivating challenge in the scientific community. The well-known approach lies in considering non-physical viscous forces that are proportional to the velocity field. A damping matrix must be defined and its identification is not based on physical considerations. This study aims at exploring the possibility of identifying a local constitutive model in order to account for damping in a natural way. To reach this objective, an experimental campaign based on reinforced concrete beams subjected to reverse three-point bending tests is presented. These results allow identifying in an accurate way the hysteretic scheme used to take into account the hysteretic phenomenon. In particular, an ad hoc hysteretic scheme is shown to be consistent in terms of energy dissipation. Numerical free vibration tests are then carried out in order to demonstrate that the use of a viscous damping can be avoided if the local constitutive concrete model accounting for hysteretic phenomenon is accurately identified. (authors)
Institute of Scientific and Technical Information of China (English)
李昭; 谷立臣; 马玉
2016-01-01
研究了前馈控制和反馈控制的原理及优缺点,提出采用负载前馈反馈复合补偿控制策略实现液压动力源在典型工况下的恒流量控制.以变转速机电液系统实验平台为基础,建立变转速液压动力源的Simulink仿真模型,分别在简单PID反馈控制和复合补偿控制策略下进行仿真和实验,结果证明了该复合补偿控制策略在液压动力源恒流量控制中的可行性和有效性,其抗负载扰动性能明显优于简单PID反馈控制.%The principles and characteristics of feedforward control and feedback control were stud-ied,a method called the load feedforward and feedback compounded compensation control strategy was proposed herein to realize the constant flow control of hydraulic power supply under typical operating conditions.Based on the experimental platform of mechanical-electrical-hydraulic system,a Simulink model of variable speed hydraulic power supply was established.The simulations and experiments were carried out respectively under a simple PID feedback control and a compounded compensation control strategy.The results verify the compounded compensation control strategy is efficient and fea-sible in constant flow control of hydraulic power supply,and the resistance to load disturbance of the compounded compensation control strategy is superior to the simple PID control .
Indian Academy of Sciences (India)
Ibrahim Eren
2008-02-01
In this study, large deﬂection of cantilever beams of Ludwick type material subjected to a combined loading consisting of a uniformly distributed load and one vertical concentrated load at the free end was investigated. In calculations, both material and geometrical non-linearity have been considered. Horizontal and vertical deﬂections magnitudes were calculated throughout Euler–Bernoulli curvature-moment relationship assuming different arc lengths. Vertical deﬂections were calculated by using Runge–Kutta method. More simple and easily understandable results have been obtained compared to the previous studies about the issue and compatible values have been obtained for most of the compared values.
DEFLECTION OF A HETEROGENEOUS WIDE-BEAM UNDER UNIFORM PRESSURE LOAD
Energy Technology Data Exchange (ETDEWEB)
T. V. Holschuh; T. K. Howard; W. R. Marcum
2014-07-01
Oregon State University (OSU) and the Idaho National Laboratory (INL) are currently collaborating on a test program which entails hydro-mechanical testing of a generic plate type fuel element, or generic test plate assembly (GTPA), for the purpose of qualitatively demonstrating mechanical integrity of uranium-molybdenum monolithic plates as compared to that of uranium aluminum dispersion, and aluminum fuel plates onset by hydraulic forces. This test program supports ongoing work conducted for/by the Global Threat Reduction Initiative (GTRI) Fuels Development Program. This study’s focus supports the ongoing collaborative effort by detailing the derivation of an analytic solution for deflection of a heterogeneous plate under a uniform, distributed load in order to predict the deflection of test plates in the GTPA. The resulting analytical solutions for three specific boundary condition sets are then presented against several test cases of a homogeneous plate. In all test cases considered, the results for both homogeneous and heterogeneous plates are numerically identical to one another, demonstrating correct derivation of the heterogeneous solution. Two additional problems are presents herein that provide a representative deflection profile for the plates under consideration within the GTPA. Furthermore, qualitative observations are made about the influence of a more-rigid internal fuel-meat region and its influence on the overall deflection profile of a plate. Present work is being directed to experimentally confirm the analytical solution’s results using select materials.
Hygrothermal Analysis and Failure Analysis of Composite Beams under Moving Loads
Hanif, Moiz
Excellent combination of high structural stiffness and low weight are the qualities of composite material leading to the extensive work on such materials. In order to achieve the desired performance requirements, the designer has to take into consideration the structural requirements and the functional characteristics. Thus, in this study, the effect of hygrothermal conditions on fiber reinforced composite laminates with moving loads have been extensively studied and has been carried out that accompanies Classical Laminate Plate Theory (CLPT) as well as First Order Shear Deformation Theory (FSDT) on MATLAB. A glass/epoxy composite system has been chosen for study with which similar results may be expected for other laminated composites. The hygrothermal effect is incorporated by adjusting the stiffness coefficients of the laminate to its level of moisture concentration using empirical relations. The failure analysis is done using the maximum normal stress criterion and the factor of safety for the lamina calculated and compared with respect to the corresponding maximum stresses and strengths. Different fiber volume fraction with varying fiber orientation of the plies in the laminate were modeled and studied. The results presented show the effect of stresses and strains in dry conditions, whereas for hygrothermal analysis, they also indicate that not all the laminates behave in a similar fashion and so it is possible by selecting the proper laminate configuration, the effect of moisture can be reduced. Also deducing, that due to hygrothermal effects, changes in the stiffness coefficients of a laminate do not appear to affect the deflection results significantly.
Institute of Scientific and Technical Information of China (English)
冯兴田; 韦统振; 齐智平
2012-01-01
Direct coupling series compensation equipments are usually used to solve many kinds of power quality problems such as voltage sag,voltage swell,voltage instantaneous interruption and so on.It will incur magnetic saturation or magnetic biasing due to the voltage change of loads with magnetic saturation characteristic when series compensation equipments are compensating.In order to solve the current inrush caused by magnetic saturation when the series compensation equipment is at the initial stage of operation,this paper analyzed the forming process of magnetic saturation and magnetic biasing,and provided the control strategy of suppressing magnetic saturation based on the magnetic balance theory.It properly uses the output of series compensation equipments to control load voltage to eliminate the magnetic saturation problem and avoid the destructive influence caused by inrush current,and realizes rapid,safe and effective compensation.The simulation and experiments results show that the inrush current is under control,and testify the effectiveness and feasibility of the proposing control strategy.%直接耦合式串联补偿装置常用来解决配电网中电压暂降、暂升以及瞬时间断等多种电能质量问题。串联补偿装置投入补偿时,具有磁饱和特性的负载由于承受电压的变化会导致磁饱和或偏磁现象。为解决串联补偿装置运行初期磁饱和带来的电流冲击,通过分析磁饱和及偏磁现象产生的过程,基于磁通平衡的原理提出磁饱和抑制策略,恰当应用串联补偿装置的输出来控制负载承受电压,消除磁饱和问题,避免冲击电流带来的破坏性影响,并实现迅速及时、安全有效的补偿。仿真与实验结果表明,冲击电流得以控制,验证了所提控制策略的有效性与可行性。
Institute of Scientific and Technical Information of China (English)
张聂鹏; 杨旭
2012-01-01
Analysis was made to load characteristics of traction power supply system. This paper raised a method which adopt-ed on-load tap changer transformer to couple capacitor groups at substation side, compensating reactive power of power supply system. The dynamic on-load tap changer coupling reactive power compensation model was established and the control strategy was studied. Simulation result has verified the validity of the above mentioned method, which effectively raises power factor of substations and reduces operation loss.% 分析了牵引供电系统的负荷特性，提出了在变电站牵引侧通过有载调压变压器耦合电容器组来补偿牵引供电系统的无功功率的方法，建立了动态有载调压耦合无功补偿模型，并对控制策略进行了研究，仿真结果验证了所提方法的有效性，通过该方法可有效提高变电站的功率因数，降低运行损耗。
Liu, Yang; Shu, Dong-Wei
2014-08-01
Delaminations in structures may significantly reduce the stiffness and strength of the structures and may affect their vibration characteristics. As structural components, beams have been used for various purposes, in many of which beams are often subjected to axial loads and static end moments. In the present study, an analytical solution is developed to study the coupled bending-torsion vibration of a homogeneous beam with a single delamination subjected to axial loads and static end moments. Euler-Bernoulli beam theory and the "free mode" assumption in delamination vibration are adopted. This is the first study of the influences of static end moments upon the effects of delaminations on natural frequencies, critical buckling loads and critical moments for lateral instability. The results show that the effects of delamination on reducing natural frequencies, critical buckling load and critical moment for lateral instability are aggravated by the presence of static end moment. In turn, the effects of static end moments on vibration and instability characteristics are affected by the presence of delamination. The analytical results of this study can serve as a benchmark for finite element method and other numerical solutions.
Joshi, A.; Suryanarayan, S.
1989-03-01
The problem of free vibration of beams having different end conditions and subjected to static initial loads has been studied with the aim of arriving at good closed-form analytical solutions. Elementary beam theory is used as a starting point to obtain the transverse vibration frequencies for various cases of classical homogeneous end conditions and for various values of the static axial load and end moment. These results indicate that it is possible to identify simple algebraic expressions which accurately represent the solution for various boundary conditions. It is also found that reasonably accurate estimates of the predominantly flexural frequency of coupled flexural-torsional vibration can be obtained from the uncoupled flexural vibration frequency of beam-columns. This is achieved by defining an effective axial load parameter, which is a combination of the axial load, the end moment and the slenderness parameter. Finally, the study also brings out that the various expressions, corresponding to different end conditions, can be combined together into a single expression for the predominantly flexural frequency. This expression is common for the boundary conditions considered here and use is made of various normalizing factors which depend on the boundary conditions, and are obtainable from the corresponding free vibration and stability analyses of beam-columns.
Losses compensation; Compensation des pertes
Energy Technology Data Exchange (ETDEWEB)
NONE
2001-07-01
One mission of RTE (Electric Power Transportation), is to watch over the losses compensation resulting from the power transport on the electric power network. Since january 2001, RTE makes good the electric losses by the purchase of energy. To choose the marketers, a consultation has been realized by RTE. This document presents the rules concerning these losses compensation. (A.L.B.)
Institute of Scientific and Technical Information of China (English)
李瑞; 王明艳; 张奥扬
2013-01-01
负载模拟器可以模拟飞行器飞行过程中受到的空气力矩，是重要的半实物仿真设备之一。针对电动负载模拟器存在的多余力矩，且严重影响了加载精度和系统的稳定性，通过在加载系统的基本结构和原理上，对加载系统进行建模，分析常规补偿法的局限性，提出改进的补偿方法，并用复合控制策略来设计控制系统。仿真结果表明，此方法能够大幅度消除多余力矩，且在工程中有一定的可行性。%Load simulator is an important equipment in hardware-in-the-loop simulation, which can simulate the air torque during aircraft flight. The extra torque existing in the motor-driven load simulator influenced the load precision and system stability. The model of load system is built based on the basic structure and principle of load system, the limitations of the conventional compensation method are analyzed, and the improved compensation method is proposed. The control system is designed by compound control strategy. The simulation results show that the method can greatly reduce the extra torque and can be used in the engineering.
Institute of Scientific and Technical Information of China (English)
游菲; 袁旭峰; 胡晟; 陈磊; 欧家祥; 张秋雁
2016-01-01
1This paper presents a new virtual load with energy feedback based on high-accuracy series compensation. A single-phase load is established firstly; and based on the topology, three-phase four-wire series compensation virtual load with energy feedback is founded. The single phase load uses main circuit topology with its AC side inductor consisting of a series capacitor and a series inductor. This topology solves effectively the problem that the required power transmission capacity cannot be met and transient current cannot be traced at the same time when choosing reactor parameter in AC side, and improves minimum value accuracy in virtual load simulation. Controller of load converter and feedback converter are designed using Quasi-PR technology. Finally, simulation model and control strategy of virtual load are constructed in PSCAD and a prototype is built. Results of simulation and experiment verify feasibility and effectiveness of the proposed method.%提出一种基于串联补偿的细粒度能馈式虚拟负载，文章首先建立单相负载，并以此为基础构建三相四线制串联补偿的细粒度能馈式虚拟负载，单相负载采用一种串联电容与串联电感来构成交流侧电抗的能馈式虚拟负载主电路拓扑结构，有效克服交流侧电感参数选择时不能同时满足功率传输容量及瞬态电流跟踪要求的缺陷，提高了虚拟负载模拟负载最小粒度的精度。利用准 PR 控制技术，设计了虚拟负载负载换流器(load converter，LC)和能馈换流器(feedback converter，FC)的控制器。最后，利用 PSCAD 软件构建了仿真模型及控制策略并搭建一套样机，通过仿真及实验结果验证了其可行性和有效性。
Institute of Scientific and Technical Information of China (English)
王丽梅; 武志涛; 刘春芳
2012-01-01
For the direct drive permanent magnet linear synchronous motor（PMLSM） servo system,the load disturbance and the parameters changes will influence the performance of the servo system seriously.A disturbance compensation method of position controller combined with optimal parameter disturbance compensating controller was proposed.It ensured that the system had fast transient response and good load disturbance rejection capability.The position controller determined the transient response performance and the load compensator improved the ability of disturbance suppression.And by using the Parseval theorem,its parameters were obtained from an optimization technique that transformed the position deviation of the performance index from time domain into the frequency domain,and then the Routh-Hurwitz two-dimensional array was calculated to obtain the optimal proportional-integral parameters.The simulation and experimental results show that the proposed compensation method enhances control precision and robustness of the system.%对于直接驱动永磁直线伺服系统,负载扰动和系统参数的变化严重影响系统伺服性能。本文提出了一种位置控制器与负载扰动补偿器相结合的扰动抑制方法,该方法同时兼顾了直线伺服系统快速的瞬时响应和良好的抗干扰能力。其中位置控制器决定系统的瞬时响应特牲,而负载扰动补偿器则用来改善系统的抗干扰能力。在负载扰动补偿器的参数确定中提出利用Parseval定理中信号在时间域内的总能量与频域内的总能量相等的原理,将位置偏差量的时域性能指标转为频域性能指标,再通过对劳斯-赫尔维茨（Routh-Hurwitz）二维数组的计算,确定最优化PI参数。仿真结果与实验表明,该补偿方法使直线电机伺服系统具有良好的控制精度与鲁棒性。
International Nuclear Information System (INIS)
In this work, active vibration suppression of a smart cantilever beam subjected to disturbances from multiple impact loadings is investigated with a point-wise fiber Bragg grating (FBG) displacement sensing system. An FBG demodulator is employed in the proposed fiber sensing system to dynamically demodulate the responses obtained by the FBG displacement sensor with high sensitivity. To investigate the ability of the proposed FBG displacement sensor as a feedback sensor, velocity feedback control and delay control are employed to suppress the vibrations of the first three bending modes of the smart cantilever beam. To improve the control performance for the first bending mode when the cantilever beam is subjected to an impact loading, we improve the conventional velocity feedback controller by tuning the control gain online with the aid of information from a higher vibration mode. Finally, active control of vibrations induced by multiple impact loadings due to a plastic ball is performed with the improved velocity feedback control. The experimental results show that active vibration control of smart structures subjected to disturbances such as impact loadings can be achieved by employing the proposed FBG sensing system to feed back out-of-plane point-wise displacement responses with high sensitivity. (paper)
Institute of Scientific and Technical Information of China (English)
周全; 徐科军; 杨双龙
2012-01-01
杆式应变天平安装在飞行器模型中,用于测量飞行器模型在风洞实验中所受的空气动力和力矩.模型相当于天平的负载.为了研究负载对天平动态特性的影响,通过改变天平上的配重砝码质量,进行不同负载下的天平动态标定实验.采用OE模型描述在不同负载下,天平各通道的数学模型.根据模型得到动态特征参数.通过曲线拟合,表示天平特征参数与负载质量之间的变化规律.为了保证在不同负载下,天平均具有较好的动态响应性能,提出依据负载变化的分段动态补偿的思路,实现对不同负载实验数据的动态补偿,取得较好效果.%In the wind tunnel experiment, bar-shaped strain gauge balance installed in aircraft model is used to measure the aerodynamic forces and moments applied to the aircraft model. The aircraft model can be regarded as the load of the balance. In order to research the effect of load on the dynamic characteristic of the balance, the dynamic calibration experiments are conducted with different loads that are realized by changing weights. The system identification method based on output error model is adopted to describe the dynamic mathematical models for various channels of the balance with different loads. Their dynamic characteristic parameters are obtained according to the models. The curve fitting method is used to present the varying pattern between the characteristic parameters of the balance and the mass of loads. A kind of staged dynamic compensation solution is proposed to ensure good dynamic response performance under different loads. It implements the dynamic compensation for experimental data of different loads, and achieves good results.
Observation of continuously loaded optical molasses
International Nuclear Information System (INIS)
The authors observed the continuous loading of a region of optical molasses for the first time, they believe. Optical molasses is the 3-D viscous confinement of atoms by the velocity-dependent forces of radiation pressure. Atoms are cooled and confined to a region defined by the intersection of three mutually orthogonal pairs of counterpropagating laser beams which are tuned slightly below the atomic resonance. Loading of the molasses region is accomplished using the slow (ν < 50-m/s) atoms which are produced continuously by laser cooling an atomic sodium beam. The beam cooling utilizes a fixed laser frequency and a spatially varying magnetic field for compensation of the changing Doppler shift
Reactive current compensation with hybrid circuit; Blindstromkompensation mit Hybridschaltung
Energy Technology Data Exchange (ETDEWEB)
Henning Mueller, Janitza
2013-06-01
Compensation systems for reactive currents have to reduce costs. However, at excessively enhanced harmonic loads compensation systems are quickly overloaded and even become cost drivers. Plants in reinforced construction and improved technology are required. During rapid load fluctuations, compensation systems can be controlled better with thyristor controllers instead of slow shooter.
Beam screen cryogenic control improvements for the LHC run 2
Bradu, Benjamin; Blanco Vinuela, Enrique; Ferlin, Gerard; Tovar-Gonzalez, Antonio
2016-01-01
This paper presents the improvements performed on the cryogenic control system for the LHC beam screens. The regulation objective is to maintain an acceptable temperature range around 20 K that ensures a good LHC beam vacuum and that limits cryogenic heat loads. In total, there are 485 regulation loops around the 27 km of the LHC machine affected by these beam disturbances. Due to the increase of the LHC performance during the run 2, standard PID controllers manage with difficulties the temperature transients of the beam screens. Several alternative control techniques have been studied and validated using dynamic simulation and then deployed on the LHC cryogenic control system in 2015. The main contribution is the addition of a feed-forward control in order to compensate the beam effects on the beam screen temperature based on the main beam parameters of the machine in real time.
Beam screen cryogenic control improvements for the LHC run 2
Bradu, Benjamin; Blanco Vinuela, Enrique; Ferlin, Gerard; Tovar-Gonzalez, Antonio
2016-01-01
This paper presents the improvements made on the cryogenic control system for the LHC beam screens. The regulation objective is to maintain an acceptable temperature range around 20 K which simultaneously ensures a good LHC beam vacuum and limits cryogenic heat loads. In total, through the 27 km of the LHC machine, there are 485 regulation loops affected by beam disturbances. Due to the increase of the LHC performance during Run 2, standard PID controllers cannot keeps the temperature transients of the beam screens within desired limits. Several alternative control techniques have been studied and validated using dynamic simulation and then deployed on the LHC cryogenic control system in 2015. The main contribution is the addition of a feed-forward control in order to compensate the beam effects on the beam screen temperature based on the main beam parameters of the machine in real time.
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
Transparent management and open information needed for the fund set up to compensate victims of the 2008 Sanlu milk scandal Almost three years after the Sanlu milk scandal that caused thousands of infants in China to develop urinary disease after drinking melamine
International Nuclear Information System (INIS)
Highlights: • Clear evidence of microscopic damage and crack formation at the notch root in the early stage of the fatigue loading (50–100 load cycles). • Propagation of fatigue crack at the notch root in the course of subsequent cyclic heat-flux loading followed by saturation after roughly 600 load cycles. • No sign of damage on the notch-free surface up to 800 load cycles. • No obvious effect of the pulse time duration on the crack extension. • Slight change in the grain microstructure due to the formation of sub-grain boundaries by plastic deformation. - Abstract: Recently, the idea of bare steel first wall (FW) is drawing attention, where the surface of the steel is to be directly exposed to high heat flux loads. Hence, the thermo-mechanical impacts on the bare steel FW will be different from those of the tungsten-coated one. There are several previous works on the thermal fatigue tests of bare steel FW made of austenitic steel with regard to the ITER application. In the case of reduced-activation steel Eurofer97, a candidate structural material for the DEMO FW, there is no report on high heat flux tests yet. The aim of the present study is to investigate the thermal fatigue behavior of the Eurofer-based bare steel FW under cyclic heat flux loads relevant to DEMO operation. To this end, we conducted a series of electron beam irradiation tests with heat flux load of 3.5 MW/m2 on water-cooled mock-ups with an engraved thin notch on the surface. It was found that the notch root region exhibited a marked development of damage and fatigue cracks whereas the notch-free surface manifested no sign of crack formation up to 800 load cycles. Results of extensive microscopic investigation are reported
Institute of Scientific and Technical Information of China (English)
成洁筠; 杨建军; 唐小弟
2008-01-01
In order to get the formulae for calculating the equivalent frame width coefficient of reinforced concrete hollow slab-column structures with edge beam,the finite element structural program was used in the elastic analysis of reinforced concrete hollow slab-column structure with different dimensions to study internal relationship between effective beam width and the frame dimensions.In addition,the formulas for calculating the increasing coefficient of edge beam were also obtained.
Couch-based motion compensation: modelling, simulation and real-time experiments
International Nuclear Information System (INIS)
The paper presents a couch-based active motion compensation strategy evaluated in simulation and validated experimentally using both a research and a clinical Elekta Precise Table™. The control strategy combines a Kalman filter to predict the surrogate motion used as a reference by a linear model predictive controller with the control action calculation based on estimated position and velocity feedback provided by an observer as well as predicted couch position and velocity using a linearized state space model. An inversion technique is used to compensate for the dead-zone nonlinearity. New generic couch models are presented and applied to model the Elekta Precise Table™ dynamics and nonlinearities including dead zone. Couch deflection was measured for different manufacturers and found to be up to 25 mm. A feed-forward approach is proposed to compensate for such couch deflection. Simultaneous motion compensation for longitudinal, lateral and vertical motions was evaluated using arbitrary trajectories generated from sensors or loaded from files. Tracking errors were between 0.5 and 2 mm RMS. A dosimetric evaluation of the motion compensation was done using a sinusoidal waveform. No notable differences were observed between films obtained for a fixed- or motion-compensated target. Further dosimetric improvement could be made by combining gating, based on tracking error together with beam on/off time, and PSS compensation. (paper)
Institute of Scientific and Technical Information of China (English)
林海军; 王震宇; 林亚平; 汪鲁才
2013-01-01
电阻应变式称重传感器存在严重的非线性误差,直接影响称重结果的准确度。本文首先阐述了称重传感器的非线性误差机理与误差补偿原理,提出了一种基于导数约束的称重传感器非线性误差补偿方法。该方法根据称重传感器输入-输出特性曲线的单调递增性,构造神经网络补偿模型训练的约束条件,完成神经网络优化设计,弥补了因训练样本不足导致的网络泛化误差大的缺陷,同时讨论了惩罚因子对网络性能的影响。实验表明,采用这种基于导数约束神经网络补偿方法( DCNN方法)的称重传感器的非线性误差远小于补偿前的误差；同时当训练样本不足时,DCNN方法比传统训练方法(仅利用数据样本训练神经网络,DINN)具有更好的泛化能力,称重准确度更高。%The nonlinear error of the resistance strain gauge load cell has heavy nonlinear error,which will lead to the low accuracy of weighing results. In this paper,the mechanism of the load cell's nonlinear error is introduced and a method for compensation on the load cell's nonlinear error based on derivatives constraints neural network ( DCNN) is proposed. In this method,the monotonically increasing characteristic of load cell's input-output function is used to construct the constraint conditions of training and optimizing the error compensation model with neural network,which can decrease the model's generalization error because of the lack of its training samples. On the other hand,the model's performance affected by the punishing factor is discussed. The experimental results show that the nonlinear error of load cell with this proposed method is far less than that without compensation,and the DCNN's generalization ability is more advantageous than the DINN( i. e. training neural network by only using data samples and not any constraint condition) ,and the weighing results of load cell with DCNN are more accurate.
Saliba, J.; Loukili, A.; Grondin, F.
2010-06-01
Creep and damage in concrete govern the long-term deformability of concrete. Thus, it is important to understand the interaction between creep and damage in order to design reliable civil engineering structures subjected to high level loading during a long time. Many investigations have been performed on the influence of concrete mixture, the effect of the bond between the matrix and the aggregates, temperature, aging and the size effect on the cracking mechanism and fracture parameters of concrete. But there is a lack of results on the influence of the creep loading history. In the present paper, an experimental investigation on the fracture properties of concrete beams submitted to three point bending tests with high levels of sustained load that deals with creep is reported. The results aim first to investigate the ranges of variation of the time response due to creep damage coupled effects under constant load and secondly to evaluate the residual capacity after creep. For this purpose a series of tests were carried out on geometrically similar specimens of size 100x200x800mm with notch to depth ratio of 0.2 in all the test specimens. The exchange of moisture was prevented and beams were subjected to a constant load of 70% and 90% of the maximum capacity. Three point bending test were realized on specimen at the age of 28 days to determine the characteristics of concrete and the maximum load so we could load the specimens in creep. Threepoint bend creep tests were performed on frames placed in a climate controlled chamber [1]. Then after four months of loading, the beams subjected to creep were removed from the creep frames and then immediately subjected to three-point bending test loading up to failure with a constant loading rate as per RILEM-FMC 50 recommendations. The residual capacity on the notched beams and the evolution of the characteristics of concrete due to the basic creep was considered. The results show that sustained loading had a strengthening
Quasi-monolithic planar load cells using built-in resonant strain gauges
Tilmans, Harrie A.C.; Elwenspoek, Miko
1993-01-01
Two load cell designs are presented using resonant strain gauges providing a frequency output. One design is based on a four-point beam deflection jig. It offers high sensitivity, but suffers from robustness and impractical geometries for a broad force range. A modified planar design (typical dimensions 1-10 mm) removes these drawbacks and in addition features built-in force reduction, overhead protection and compensation of common mode effects. Load ranges vary from high (1 500 N) to very lo...
Energy Technology Data Exchange (ETDEWEB)
Becchetti, F.D., E-mail: fdb@umich.edu [Department of Physics, Randall Lab, University of Michigan, Ann Arbor MI 48109 (United States); Jiang Hao; Ojaruega, M.; Torres-Isea, R.O. [Department of Physics, Randall Lab, University of Michigan, Ann Arbor MI 48109 (United States); Villano, A.N. [Department of Physics, Randall Lab, University of Michigan, Ann Arbor MI 48109 (United States); University of Notre Dame, Notre Dame IN 46556 (United States); Kolata, J.J.; Roberts, A. [University of Notre Dame, Notre Dame IN 46556 (United States)
2011-10-01
Improved time-of-flight (ToF) capability has been added to University of Michigan (UM)-University of Notre Dame (UND) TwinSol low-energy dual 6T solenoid-based radioactive nuclear-beam (RNB) facility at the UND FN tandem Van de Graaff accelerator. An extended low-background beam line has been combined with a newly-constructed ca.1 meter diameter ISO-250 based scattering chamber capable of sub-ns ToF of RNBs. These together with the intrinsic, low ToF spread in the TwinSol ion-optical system yields improved ToF information for low-energy RNB nuclear reaction studies. Using either the intrinsic accelerator bunched and pulsed-selected beams with RF timing, or with the addition of an MCP+foil timing system (or similar) detector at the dual-solenoid cross-over region allows for reduction of the energy spread inherent in these low-energy RNB reactions. As an example, using the ToF information reduces the FWHM energy spread in a high-intensity 28 MeV {sup 8}Li beam from about 1 MeV to
Compensation Techniques in Accelerator Physics
Energy Technology Data Exchange (ETDEWEB)
Sayed, Hisham Kamal [Old Dominion Univ., Norfolk, VA (United States)
2011-05-01
Accelerator physics is one of the most diverse multidisciplinary fields of physics, wherein the dynamics of particle beams is studied. It takes more than the understanding of basic electromagnetic interactions to be able to predict the beam dynamics, and to be able to develop new techniques to produce, maintain, and deliver high quality beams for different applications. In this work, some basic theory regarding particle beam dynamics in accelerators will be presented. This basic theory, along with applying state of the art techniques in beam dynamics will be used in this dissertation to study and solve accelerator physics problems. Two problems involving compensation are studied in the context of the MEIC (Medium Energy Electron Ion Collider) project at Jefferson Laboratory. Several chromaticity (the energy dependence of the particle tune) compensation methods are evaluated numerically and deployed in a figure eight ring designed for the electrons in the collider. Furthermore, transverse coupling optics have been developed to compensate the coupling introduced by the spin rotators in the MEIC electron ring design.
Extended frequency compensation of a diamagnetic loop
International Nuclear Information System (INIS)
A method of compensation for a diamagnetic loop that is magnetically coupled to a concentric stainless-steel vacuum vessel is presented. This compensation method accounts for imperfect magnetic coupling between the vessel eddy currents, the diamagnetic loop, and the plasma diamagnetic currents, and it also corrects for a finite loading resistance on the diamagnetic loop. A procedure for adjusting and calibrating the active-filter compensation circuit is presented. It can be applied to internal or external diamagnetic loops. (author)
Directory of Open Access Journals (Sweden)
Minkwan Ju
2015-01-01
Full Text Available This study intends to investigate the flexural bond performance of glass fiber-reinforced polymer (GFRP reinforcing bar under repeated loading. The flexural bond tests reinforced with GFRP reinforcing bars were carried out according to the BS EN 12269-1 (2000 specification. The bond test consisted of three loading schemes: static, monotonic, and variable-amplitude loading to simulate ambient loading conditions. The empirical bond length based on the static test was 225 mm, whereas it was 317 mm according to ACI 440 1R-03. Each bond stress on the rib is released and bonding force is enhanced as the bond length is increased. Appropriate level of bond length may be recommended with this energy-based analysis. For the monotonic loading test, the bond strengths at pullout failure after 2,000,000 cycles were 10.4 MPa and 6.5 MPa, respectively: 63–70% of the values from the static loading test. The variable loading test indicated that the linear cumulative damage theory on GFRP bonding may not be appropriate for estimating the fatigue limit when subjected to variable-amplitude loading.
Directory of Open Access Journals (Sweden)
Yusuf Yesilce
2012-01-01
Full Text Available In the existing reports regarding free and forced vibrations of the beams, most of them studied a uniform beam carrying various concentrated elements using Bernoulli-Euler Beam Theory (BET but without axial force. The purpose of this paper is to utilize the numerical assembly technique to determine the exact frequency-response amplitudes of the axially-loaded Timoshenko multi-span beam carrying a number of various concentrated elements (including point masses, rotary inertias, linear springs and rotational springs and subjected to a harmonic concentrated force and the exact natural frequencies and mode shapes of the beam for the free vibration analysis. The model allows analyzing the influence of the shear and axial force and harmonic concentrated force effects and intermediate concentrated elements on the dynamic behavior of the beams by using Timoshenko Beam Theory (TBT. At first, the coefficient matrices for the intermediate concentrated elements, an intermediate pinned support, applied harmonic force, left-end support and right-end support of Timoshenko beam are derived. After the derivation of the coefficient matrices, the numerical assembly technique is used to establish the overall coefficient matrix for the whole vibrating system. Finally, solving the equations associated with the last overall coefficient matrix one determines the exact dynamic response amplitudes of the forced vibrating system corresponding to each specified exciting frequency of the harmonic force. Equating the determinant of the overall coefficient matrix to zero one determines the natural frequencies of the free vibrating system (the case of zero harmonic force and substituting the corresponding values of integration constants into the related eigenfunctions one determines the associated mode shapes. The calculated vibration amplitudes of the forced vibrating systems and the natural frequencies of the free vibrating systems are given in tables for different values of
Research on Shear Behavior of Reinforced Concrete Beam Under Uniform Load%均匀受力的混凝土深梁抗剪性能
Institute of Scientific and Technical Information of China (English)
刘君阳; 杨梅
2014-01-01
主要通过有限元软件模拟研究混凝土深梁在均布荷载作用下，纵筋配筋率、混凝土强度等两个因素对其抗剪性能的影响。结果表明：随着纵筋配筋率的增大，深梁的产生切应力不断减小，随着混凝土的强度的增大，深梁的产生切应变不断减小，说明纵筋配筋率和混凝土强度的增大对提高梁的抗剪性能有利。%This paper mainly through the finite element software simulation research on reinforced concrete deep beams under uniform load ,reinforcement ratio and concrete strength affect the performance of the shear .+The re-sults show that with the increase of the ratio of longitudinal reinforcement and depth ,the generation of deep beam shear stress decreases continuously ,with the increase of the strength of the concrete ,the generation of deep beam shear strain decreases constantly ,suggests that the increase of the longitudinal reinforcement reinforcement ratio and concrete strength is good for increase the shear properties of the beam .
Fei Xiang
1999-01-01
Harmonic potentials can be produced in cylindrical ion traps by means of dynamic orthogonalized anharmonicity compensation with use of two (or multiple) sets of compensation electrodes. One special example is for traps with multiple identical electrodes which are not only easy to construct and allow access to the center region of the trap for particle loading and releasing, laser beams, and microwaves, but also flexible in forming harmonic potential wells in many locations. The nested trap configuration and the side-by-side trap configuration are readily available in this special scheme. Analytical solutions for cylindrical traps with multiple sets of compensation potentials are presented. This work will be useful for studies involving Penning trap diagnostics, atomic and molecular interactions (including the production of antihydrogen atoms), accurate mass measurements of exotic particles, and precision measurements of the spin precession frequencies of trapped particles.
International Nuclear Information System (INIS)
A recent study investigated the feasibility to develop a bench-top x-ray fluorescence computed tomography (XFCT) system capable of determining the spatial distribution and concentration of gold nanoparticles (GNPs) in vivo using a diagnostic energy range polychromatic (i.e. 110 kVp) pencil-beam source. In this follow-up study, we examined the feasibility of a polychromatic cone-beam implementation of XFCT by Monte Carlo (MC) simulations using the MCNP5 code. In the current MC model, cylindrical columns with various sizes (5-10 mm in diameter) containing water loaded with GNPs (0.1-2% gold by weight) were inserted into a 5 cm diameter cylindrical polymethyl methacrylate phantom. The phantom was then irradiated by a lead-filtered 110 kVp x-ray source, and the resulting gold fluorescence and Compton-scattered photons were collected by a series of energy-sensitive tallies after passing through lead parallel-hole collimators. A maximum-likelihood iterative reconstruction algorithm was implemented to reconstruct the image of GNP-loaded objects within the phantom. The effects of attenuation of both the primary beam through the phantom and the gold fluorescence photons en route to the detector were corrected during the image reconstruction. Accurate images of the GNP-containing phantom were successfully reconstructed for three different phantom configurations, with both spatial distribution and relative concentration of GNPs well identified. The pixel intensity of regions containing GNPs was linearly proportional to the gold concentration. The current MC study strongly suggests the possibility of developing a bench-top, polychromatic, cone-beam XFCT system for in vivo imaging.
Rectangular Laser Resonators with Astigmatic Compensation
DEFF Research Database (Denmark)
Skettrup, Torben
2005-01-01
An investigation of rectangular resonators with a view to the compensation of astigmatism has been performed. In order to have beam waists placed at the same positions in the tangential and sagittal planes, pairs of equal mirrors were considered. It was found that at least two concave mirrors...... are necessary to obtain compensation. Four-concave-mirror systems are most stable close to the quadratic geometry, although the symmetric quadratic resonator itself cannot be compensated for astigmatism. Using four equal concave mirrors, compensation of astigmatism can be obtained in two arms at the same time....... Usually several stability ranges are found for four-mirror resonators with pair-wise equal mirrors, and it is possible with these systems to obtain small compensated beam waist radii suitable for frequency conversion. Relevant formulae are given and several relevant examples are shown using simulation...
Loewenhoff, Thorsten Werner
2012-01-01
The increasing world energy needs lead to strong efforts in today's energy R&D trying to open up new energy resources. One possible option to access energy in large scale power plants is to use the process of nuclear fusion to generate heat and, from that, electricity with conventional steam turbine technology. However, the realisation is technologically and scientifically very challenging. The heat fluxes that load the inner walls of a fusion device, especially the most severely loaded part,...
Institute of Scientific and Technical Information of China (English)
李慧
2012-01-01
该文提出了一种通过加装带滤波器的静止无功补偿器（SVC）,使负序引起的不平衡功率和谐波功率流入SVC,最终达到平衡系统目的的方法;提出基于前馈-反馈复合控制的SVC不平衡负荷补偿方法,将电压闭环控制与三相不平衡控制相结合、功率因数闭环控制与三相不平衡控制相结合,以达到适应各种工况的需求。最后,该文在SVC相关理论研究的基础上搭建了仿真模型,仿真结果表明该文提出控制方法的正确性和可行性。%Based on the analysis of three-phase unbalanced system＇s instantaneous power,this paper proposes a method that by installing SVC compensator with a filter to make the imbalance power caused by negative sequence and harmonic power flowing into the SVC and achieve the ultimate objective of a balanced system.A feedforward-feedback composite control method on the unbalanced load compensation of SVC is also given in this paper,which take the voltage loop control and three-phase unbalance control integrated as well as make power factor loop combining with the three-phase unbalanced control.It is proved that this method can meet the needs of various working conditions.The simulation model is built based on the SVC theory,simulation results show that this control method is correct and feasible.
Low Current, Long Beam Pulse with SLED
International Nuclear Information System (INIS)
The 3 km long linac at the Stanford Linear Accelerator Center (SLAC) is used for fixed target experiments such as E-155, with energies up to 50 GeV. The SLAC Energy Development (SLED) system increase the maximum no-load energy by a factor of 1.6, but it also causes a varying beam energy curve. To provide a long pulse or bunch train for the experiment the energy profile has to be flat. Besides more sophisticated methods such as varying the phase of two klystrons feeding one structure section as proposed in the NLC design, we describe the method used for E-155 in spring of 1997. The desired low charged beam didn't have any significant beam loading, but by inserting a 1800 phase notch during the SLED pulse, a beam pulse of up to 500 ns was achieved. The energy range without compensation would have been 15%, while with compensation the energy spread was reduced to about 0.15%. The phase notch was achieved by triggering a pair of two additional 180d0 phase switches about half a structure fill-time after the SLED pulse was triggered. Simulations are compared with the experimental result
Institute of Scientific and Technical Information of China (English)
叶宏伟
2015-01-01
The research on the system of district cooling project of 10 kV 20/10 kV-10 000 kVA chiller special transformer deployment method and reactive power compensation system is set up, and using the interaction of cutting the capacitive reactive compensation system and play a resistance of reactive power compensation for the first time a full electromagnetic, effectively solves the system reactive power the compensated demand in the no-load and full load when the great difference of reactive power compensation demand problem.%研究了区域集中供冷项目10 kV冷水机组专用20/10 kV-10000 kVA变压器的系统部署方法和无功补偿系统的设置，并采用了全电磁一次投切的容性无功补偿系统和发挥了抗性无功补偿的相互作用，有效解决了系统在空载时无功补偿需求与全负荷时无功补偿需求的巨大差异问题。
A Novel Approach for Simulation of Transmission Line Compensation
Directory of Open Access Journals (Sweden)
Parag Nijhawan
2010-10-01
Full Text Available This paper presents an efficient method based on bus power injection for transmission line compensation. In this method, the load flow solution is first obtained using specified generations and loads. The terminal buses connecting the line to be compensated and the compensation level are identified. The differences of the line flows before and after compensation are injected in or out of the two terminal buses. The proposed method has been successfully used tosimulate compensation of transmission line by a series capacitor and then by SSSC.
Reducing workers' compensation costs.
Killian, M J
1994-01-01
Employers can reduce their workers' compensation costs by encouraging internal communication and education before and after injuries occur. Comprehensive workers' compensation programs can be developed by integrating the management of employee benefits and workers' compensation claims. PMID:10133659
型钢混凝土梁正截面受弯承载力的设计%Design of Normal Section Loading of Steel Reinforced Concrete Beam
Institute of Scientific and Technical Information of China (English)
张涛
2013-01-01
There are more and more extensive application of steel reinforced concrete in high strength, high stiffness, large span structure. In the substation, the design of secondary device room, due to the large span, I use the design of steel reinforced concrete beams. In structure design, the beam cross-section flexural and oblique section shear is the main design process. This paper introduces the normal section of reinforced concrete beams according to the ultimate bearing capacity of basic assumptions and the practical engineering calculation of normal section bearing capacity calculation, and introduces the calculation of bearing capacity of main factors affecting the shear strength of the beams and the practical oblique section, are greater than the load, can be applied in practice.%型钢混凝土在高强度、高刚度、大跨度结构中有越来越广泛的应用，在变电所二次设备室设计中，由于跨度较大，使用了型钢混凝土梁的设计。结构设计中，梁正截面的受弯和斜截面的受剪是主要设计过程，本文介绍了型钢混凝土梁正截面按极限承载力计算时的基本假定和工程实际正截面承载力的计算，同时介绍了影响梁斜截面抗剪的主要因素和工程实际斜截面承载力的计算，均大于荷载作用，能够在实际中得到应用。
Dorward, R. C.; Hasse, K. R.
1978-01-01
A comparison is made between measurements of stress-corrosion crack propagation made by a constant-load procedure and by a constant-deflection procedure. Precracked double cantilever beam specimens from 7075 aluminum alloy plate were used. The specimens were oriented in such a way that cracking would begin in the short-transverse plane and would propagate in the rolling direction. The specimens were subjected to a buffered salt-chromate solution and a 3.6% synthetic sea salt solution. The measurements were made optically with a binocular microscope. Stress intensities and crack lengths were calculated and crack velocities were obtained. Velocity was plotted against the average calculated stress intensity. Good agreement between the two methods was found for the salt-chromate solution, although some descrepancies were noted for the artificial sea salt solution.
Directory of Open Access Journals (Sweden)
Onur SAYMAN
2001-03-01
Full Text Available In the present study, an elastic-plastic stress analysis is carried out in a metal matrix composite cantilever beam loaded by a single force at its free end. A composite consisting of stainless-steel reinforced aluminium was produced for this work. The orientation angle of the fibers is chosen as 0°, 30°, 45°, 60° and 90°. The material is assumed to be perfectly plastic in the elasto-plastic solution. An analytical solution is performed for satisfying both the governing differential equation in the plane stress case and boundary conditions for small plastic deformations. The solution is carried out under the assumption of the Bernoulli-Navier hypotheses. The composite material is assumed as hardening linearly. The Tsai-Hill theory is used as a yield criterion.
Energy Technology Data Exchange (ETDEWEB)
Gao, F.; High Energy Physics; Illinois Inst. of Tech
2009-07-24
Power extraction using a dielectric-loaded (DL) waveguide is a way to generate high-power radio frequency (RF) waves for future particle accelerators, especially for two-beam-acceleration. In a two-beam-acceleration scheme, a low-energy, high-current particle beam is passed through a deceleration section of waveguide (decelerator), where the power from the beam is partially transferred to trailing electromagnetic waves (wakefields); then with a properly designed RF output coupler, the power generated in the decelerator is extracted to an output waveguide, where finally the power can be transmitted and used to accelerate another usually high-energy low-current beam. The decelerator, together with the RF output coupler, is called a power extractor. At Argonne Wakefield Accelerator (AWA), we designed a 7.8GHz power extractor with a circular DL waveguide and tested it with single electron bunches and bunch trains. The output RF frequency (7.8GHz) is the sixth harmonic of the operational frequency (1.3GHz) of the electron gun and the linac at AWA. In single bunch excitation, a 1.7ns RF pulse with 30MW of power was generated by a single 66nC electron bunch passing through the decelerator. In subsequent experiments, by employing different splitting-recombining optics for the photoinjector laser, electron bunch trains were generated and thus longer RF pulses could be successfully generated and extracted. In 16-bunch experiments, 10ns and 22ns RF pulses have been generated and extracted; and in 4-bunch experiments, the maximum power generated was 44MW with 40MW extracted. A 26GHz DL power extractor has also been designed to test this technique in the millimeter-wave range. A power level of 148MW is expected to be generated by a bunch train with a bunch spacing of 769ps and bunch charges of 20nC each. The arrangement for the experiment is illustrated in a diagram. Higher-order-mode (HOM) power extraction has also been explored in a dual-frequency design. By using a bunch
Re-planning for compensator-based IMRT with original compensators.
Zhang, Geoffrey; Feygelman, Vladimir; Stevens, Craig; Li, Weiqi; Leuthold, Susan; Springett, Gregory; Hoffe, Sarah
2011-01-01
Compared with multileaf collimator (MLC)-based intensity-modulated radiotherapy (IMRT) for moving targets, compensator-based IMRT has advantages such as shorter beam-on time, fewer monitor units with potentially decreased secondary carcinogenesis risk, better optimization-to-deliverable dose conversion, and often better dose conformity. Some of the disadvantages include additional time for the compensators to be built and delivered, as well as extra cost. Patients undergoing treatment of abdominal cancers often experience weight loss. It would be necessary to account for this change in weight with a new plan and a second set of compensators. However, this would result in treatment delays and added costs. We have developed a method to re-plan the patient using the same set of compensators. Because the weight changes seen with the treatment of abdominal cancers are usually relatively small, a new 4D computed tomography (CT) acquired in the treatment position with markers on the original isocenter tattoos can be registered to the original planning scan. The contours of target volumes from the original scans are copied to the new scan after fusion. The original compensator set can be used together with a few field-in-field (FiF) beams defined by the MLC (or beams with cerrobend blocks for accelerators not equipped with a MLC). The weights of the beams with compensators are reduced so that the FiF or blocked beams can be optimized to mirror the original plan and dose distribution. Seven abdominal cancer cases are presented using this technique. The new plan on the new planning CT images usually has the same dosimetric quality as the original. The target coverage and dose uniformity are improved compared with the plan without FiF/block modification. Techniques combining additional FiF or blocked beams with the original compensators optimize the treatment plans when patients lose weight and save time and cost compared with generating plans with a new set of compensators.
Institute of Scientific and Technical Information of China (English)
葛若东; 梁进修; 王磊
2012-01-01
在不同荷载条件下,对8根钢筋混凝土梁进行试验,研究短期疲劳荷载作用下的变形、应力分布以及短期疲劳荷载作用后的力学指标。试验结果和分析表明：疲劳荷载对锈蚀钢筋混凝土梁的影响较大,明显降低试验梁的极限强度和延性;碳纤维加固后的锈蚀混凝土梁的极限承载力明显提高,且在破坏时具有良好的延性,承载力极限值可以提高22%～47%。碳纤维＂U＂形箍对试验梁的性能影响较大,没有粘贴＂U＂形箍的碳纤维加固试验梁在后期加载过程中,由于混凝土保护层的突然脱落而发生破坏。采用碳纤维材料加固后的较低锈蚀率的钢筋混凝土梁在经过短期疲劳荷载后依然能够具有良好的力学性能。%Eight RC beams including four CFRP strengthened beams were tested after short-term fatigue. The distortion, stress distribution, ultimate load of corroded reinforced concrete beams were investigated. Both the experimental and analytical results indicated that fatigue loading had a significant impact on the performance of corroded RC beams; It could reduce the ultimate strength and ductility of the beams substantially. The ultimate load- carrying capacity of the CFRP-strengthened corroded beams are enhanced evidently and had a preferable ductility during damage. The loading capacity of RC beams with CFRP strengthened was in creased by 22% to 47%. The U- wrap CFRP sheet had an obvious effect on beams, the potential delamination of the concrete cover following steel corrosion could cause sudden failure of RC beams strengthened with CFRP at later loading stages. Repairing a low corrosion rate beams by CFRP still had good mechanical properties after a short-term fatigue loadings.
Directory of Open Access Journals (Sweden)
Armando Jaime Ustariz-Farfan
2012-08-01
Full Text Available El interés creciente de utilizar filtros activos de potencia para compensar las corrientes no sinusoidales producidas por las cargas no lineales ha aumentado el uso de la teoría instantánea de potencia reactiva. Sin embargo, esta teoría se puede aplicar solamente a los sistemas trifásicos de tres o cuatro conductores. Este artículo presenta una nueva definición de la potencia instantánea que puede ser aplicada a todos los sistemas polifásicos. Así, el concepto de producto tensorial es introducido para definir el tensor instantáneo de potencia y también la descomposición de la corriente en las componentes activas y reactivas sin importar el número de fases del sistema eléctrico. Finalmente, un análisis exhaustivo de casos prácticos se ha realizado a nivel de simulación, los cuales han permitido que el enfoque propuesto sea verificado.The use of the instantaneous reactive power theory is greater than before due to the increased interest to use active power filters to compensate the non-sinusoidal currents produced by nonlinear loads. However, this theory can only be applied to three-phase systems of three or four conductors. This paper presents a new definition of instantaneous power that can be applied to all multiphase systems. Thus, the concept of tensor product is introduced to define the instantaneous power tensor and also the current decomposition in active and reactive components regardless of the number of phases of the power system. Finally, an exhaustive analysis of practical cases has been carried out at a simulation level which verified the proposed approach.
Optical molasses loaded from a slow atomic beam%应用慢速原子束制备冷原子粘团的研究
Institute of Scientific and Technical Information of China (English)
陈江; 张辉; 阮军; 王心亮; 刘丹丹; 张首刚
2012-01-01
Preparation of the optical molasses is one of the key steps for developing a fountain clock. The optical molasses is loaded from a slow atomic beam, and the fluorescence collection method is applied to determine the number of atoms in the optical molasses, meanwhile the time-of-flight(TOF) method is used to measure the temperature of the optical molasses. The number of cold atoms in the optical molasses for loading time of 200 ms is determined to be (8.14±0.2)×107, and the temperature of cold atoms is determined to be (10.72±0.69) μK.%冷原子粘团的制备是喷泉钟研制的关键步骤之一。通过慢速原子束加载获得冷原子粘团，应用荧光收集法测量了冷原子粘团的原子数目，采用飞行时间法测量了冷原子粘团温度。冷原子粘团中原子数目在加载时间200ms的情况下为（8．14±0．2）×107，温度为（10．72±0．69）μK。
Small Angle Crab Compensation for LHC IR Upgrade
Akai, K; Dorda, U; Ohmi, K; Oide, K; Tomás, R; Zimmermann, T
2007-01-01
A small angle crab scheme is being considered for the LHC luminosity upgrade. In this paper we present a 400MHz superconducting cavity design and discuss the pertinent RF challenges. We also present a study on the beam-beam performance and proton-beam emittance growth in the presence of crab compensation, with RF noise sources.
Improved charge amplifier using hybrid hysteresis compensation
Amin-Shahidi, Darya; Trumper, David L.
2013-08-01
We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design.
Reactive power compensation a practical guide
Hofmann, Wolfgang; Just, Wolfgang
2012-01-01
The comprehensive resource on reactive power compensation, presenting the design, application and operation of reactive power equipment and installations The area of reactive power compensation is gaining increasing importance worldwide. If suitably designed, it is capable of improving voltage quality significantly, meaning that losses in equipment and power systems are reduced, the permissible loading of equipment can be increased, and the over-all stability of system operation improved. Ultimately, energy use and CO2 emisson are reduced. This unique guide discusses the
Institute of Scientific and Technical Information of China (English)
王坚; 韩刚; 樊涛
2012-01-01
分析了圆管带式输送机平行弦桁架梁所承受的载荷类型,并给出了载荷大小的确定方法,对桁架梁各杆件的受力特点进行分析,运用截面法得出最危险杆件的内力简化计算公式.%This paper analyzes types of the loads carried by parallel string truss beam of pipe belt conveyor, proposes the load determination method, and analyzes the load-carrying characteristics of member bars of the truss beam, so that ihe internal force simplified calculation formula for the most dangerous member bar is figured out by the section method.
Energy Technology Data Exchange (ETDEWEB)
Desbat, L. [Universite Joseph Fourier, UMR CNRS 5525, 38 - Grenoble (France); Roux, S. [Universite Joseph Fourier, TIMC-IMAG, In3S, Faculte de Medecine, 38 - Grenoble (France)]|[CEA Grenoble, Lab. d' Electronique et de Technologie de l' Informatique (LETI), 38 (France); Grangeat, P. [CEA Grenoble, Lab. d' Electronique et de Technologie de l' Informatique (LETI), 38 (France)
2005-07-01
This work is a contribution to the compensation of motion in tomography. New classes of deformation are proposed, that compensates analytically by an algorithm of a F.B.P. type reconstruction. This work makes a generalisation of the known results for affine deformations, in parallel geometry and fan-beam, to deformation classes of infinite dimension able to include strong non linearities. (N.C.)
Institute of Scientific and Technical Information of China (English)
杨骁; 蔡赟姝
2008-01-01
Nonlinear bending of cantilever incompressible poroelastic beams subjected to a uniform load is investigated with the constraint that fluid flow is only in the axial direction. The governing equations for large deflection of the poroelastic beam are derived from theory of incompressible saturated porous media. Then, nonlinear responses of a cantilever beam with impermeable fixed end and permeable free end are examined with the Galerkin truncation method. The deflections and bending moments of the poroelastie beam and the equivalent couples of the pore fluid pressures are shown in figures. The differences of the results between the large deflection and the small deflection theories are analyzed. It is shown that the results of the large deflection theory are smaller than those of the small deflection theory, and the time needed to approach their stationary states for the large deflection theory is shorter than that for the small deflection theory.
Essays in Executive Compensation
D. Zhang (Dan)
2012-01-01
textabstractThis dissertation focuses on how executive compensation is designed and its implications for corporate finance and government regulations. Chapter 2 analyzes several proposals to restrict CEO compensation and calibrates two models of executive compensation that describe how firms would r
Design and implementation of adaptive slope compensation in current mode DC-DC converter
Energy Technology Data Exchange (ETDEWEB)
Guo Zhongjie; Wu Longsheng; Liu Youbao, E-mail: guozhongjie4213@126.com [Xi' an Microelectronic Technology Institute, Xi' an 710054 (China)
2010-12-15
To improve the compensation for the inherent instability in a current mode converter, the adaptive slope compensation, giving attention to the problems of the traditional compensation on compensation accuracy, loading capability and turning jitter, is presented. Based on the analysis of current loop, by detecting the input and output voltage, converting the adaptive slope compensation current, the compensation of the current loop is optimized successfully. It can not only improve the compensation accuracy but also eliminate the over compensation, the turning jitter and the poor loading capability in the reported slope compensation. A power supply chip with adaptive slope compensation has been fabricated in a 0.35 {mu}m CMOS process. The measurement results show that the chip starts up and operates steadily with the constant current limit under conditions of 5 V input voltage, from 10% to 100% duty cycle. (semiconductor integrated circuits)
铁路简支梁桥竖向有载频率研究%study on vertical loaded frequencies of railway simply supported beam bridges
Institute of Scientific and Technical Information of China (English)
苏木标; 李建中; 梁志广
2001-01-01
The vertical loaded free frequencies for the different span simply supported beam bridges are investigated with the vehicle-bridge system model. The results show that these frequencies of the bridge are periodic changed in all the process in which a train moves on the bridge, and the values of the frequencies have the relation with not only the distribution of the stiffness and the mass of the bridge self, but also the stiffness of the spring and the mass under the spring for each wheel-set of the vehicles running on the bridge.%采用车-桥系统相互作用的计算模型，对不同跨度简支梁桥的竖向有载自振频率进行了深入研究。结果表明，桥梁的竖向有载自振频率在列车过桥全过程中是周期性变化的，其数值不仅与桥梁本身的刚度和质量分布有关，同时还与桥上车辆各轮对悬挂弹簧的刚度和簧下质量及其在桥上的位置有关。
DEFF Research Database (Denmark)
Flor, Christian Riis; Frimor, Hans; Munk, Claus
2014-01-01
We derive the optimal compensation contract in a principal–agent setting in which outcome is used to provide incentives for both effort and risky investments. To motivate investment, optimal compensation entails rewards for high as well as low outcomes, and it is increasing at the mean outcome...... to motivate effort. If rewarding low outcomes is infeasible, compensation consisting of stocks and options is a near-efficient means of overcoming the manager's induced aversion to undertaking risky investments, whereas stock compensation is not. However, stock plus option compensation may induce excessively...
Compensators for IMRT - an investigation in quality assurance
International Nuclear Information System (INIS)
Intensity modulated radiotherapy (IMRT) allows dose distributions which adequately consider organs at risk (OAR) and dose homogeneity to the target volume. This is practically reached by conforming the beam profiles to the shape of the planning target volume (PTV), by shaping the fluence with multileaf collimators (MLC) or compensators. Though compensator production is time consuming and seems less convenient than the use of MLC, compensators offer much easier quality assurance. In this study the effects of certain simplifications of compensator production were studied. Compensators were produced and ionization chamber measurements in a water phantom and film measurements in a solid phantom were performed to verify the compensators. The results of the measurements were compared to the fluence distributions given by the planning system. The measurements were meant to show how realistic the investigated simplifications were, and to reveal a suitable and reliable testing method for compensators. Monte-Carlo calculations employing the EGS 4 Code were further performed to support the measurements. (orig.)
Selective compensation of voltage harmonics in grid-connected microgrids
DEFF Research Database (Denmark)
Savaghebi, Mehdi; Vasquez, Juan Carlos; Jalilian, Alireza;
2013-01-01
fundamental frequency to enhance power control and also at harmonic frequencies to improve the nonlinear load sharing among DGs. The control system design is discussed in detail. The presented simulation results demonstrate the effectiveness of the proposed method in compensation of the voltage harmonics to......In this paper, a novel approach is proposed for selective compensation of main voltage harmonics in a grid-connected microgrid. The aim of compensation is to provide a high voltage quality at the point of common coupling (PCC). PCC voltage quality is of great importance due to sensitive loads that...... may be connected. It is assumed that the voltage harmonics are originated from distortion in grid voltage as well as the harmonic current of the nonlinear loads. Harmonic compensation is achieved through proper control of distributed generators (DGs) interface converters. The compensation effort of...
International Nuclear Information System (INIS)
This invention relates to an electromechanical energy converter with inertial energy storage. The device, a single phase, two or multi-pole alternator with stationary field coils, and a rotating armature is provided. The rotor itself may be of laminated steel for slower pulses or for faster pulses should be nonmagnetic and electrically nonconductive in order to allow rapid penetration of the field as the armature coil rotates. The armature coil comprises a plurality of power generating conductors mounted on the rotor. The alternator may also include a stationary or counterrotating compensating coil to increase the output voltage thereof and to reduce the internal impedance of the alternator at the moment of peak output. As the machine voltage rises sinusoidally, an external trigger switch is adapted to be closed at the appropriate time to create the desired output current from said alternator to an external load circuit, and as the output current passes through zero a self-commutating effect is provided to allow the switch to disconnect the generator from the external circuit
Linearizing Intra-Train Beam-Beam Deflection Feedback
International Nuclear Information System (INIS)
Beam-beam deflection feedback acting within the crossing time of a single bunch train may be needed to keep linear collider beams colliding at high luminosity. In a short-pulse machine such as the Next Linear Collider (NLC) this feedback must converge quickly to be useful. The non-linear nature of beam-beam deflection vs. beam-beam offset in these machines precludes obtaining both rapid convergence and a stable steady-state lock to beam offsets with a linear feedback algorithm. We show that a simply realizable programmable non-linear amplifier in the feedback loop can linearize the feedback loop, approximately compensating the beam-beam deflection non-linearity. Performance of a prototype non-linear amplifier is shown. Improvement of convergence and stability of the beam-beam feedback loop is simulated
Herr, W
2014-01-01
One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.
Harmonic currents Compensator Grid-Connected Inverter at the Microgrid
DEFF Research Database (Denmark)
Asuhaimi Mohd Zin, A.; Naderipour, A.; Habibuddin, M.H.;
2016-01-01
loads are unbalanced and/or nonlinear and also compensate of the harmonic currents and control the active and reactive power. The main advantage and objective of this method is to effectively compensate for the harmonic currents content of the grid current and microgrid without using any compensation......The main challenge associated with the grid-connected inverter in distributed generation (DG) systems is to maintain the harmonic contents in output current below the specified values and compensates for unbalanced loads even when the grid is subject to disturbances such as harmonic distortion...... and unbalanced loads. To overcome these challenges, a current control strategy for a three-phase grid-connected inverter under unbalanced and nonlinear load conditions is presented. It enables grid-connected inverter by the proposed control method to inject balanced clean currents to the grid even when the local...
Simulations of beam-beam and beam-wire interactions in RHIC
Energy Technology Data Exchange (ETDEWEB)
Kim, Hyung J.; Sen, Tanaji; /Fermilab; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven
2009-02-01
The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.
Institute of Scientific and Technical Information of China (English)
周芝林; 黄培彦; 郭馨艳
2008-01-01
The static and fatigue tests under cyclic bending loads at different ambient temperatures of 20 ℃ and 80℃ are carried out to investigate the fatigue behavior of the reinforced concrete(RC) beams strengthened with'carbon fi-ber laminates(CFLs). The failure modes of the strengthened beams include CFLs debonded near the mid-span and steel rebar yielded or broken. S-N curves of strengthened beams are developed according to the test results. The fa-tigue limit, load versus deflection curves and strain response of strengthened beams are obtained as well. The results show that the fatigue behaviors of the strengthened beams are not significantly influenced by the ambient tempera-tures (lower than 80℃) when the fatigue load levels equal 25.0 kN, 27.5 kN and 30.0 kN.%为了研究碳纤维薄板增强钢筋混凝土梁在不同温度下的疲劳性能,分别在20℃和80℃的温度条件下对26根增强梁进行了三点弯曲静载和疲劳试验.结果表明:当疲劳载荷水平为25.0 kN,27.5 kN和30.0 kN时,试件的S-N曲线、疲劳极限、破坏模式、挠度曲线和应变反映受环境温度的影响较小.
Directory of Open Access Journals (Sweden)
Astawa Made Dharma
2016-01-01
Full Text Available This research designed a partial prestressed concrete beam-column with reinforced concrete interior joint, using square columns of 400/400 mm, reinforcement 6 D16 + 4D13, section beam 250/400 mm, tensile reinforcement 5 D13, compression reinforcement 3 D13 + 2 strand tendon D12,7 mm , and joint without plastic hinge, then tested in laboratory with lateral cyclic loads on peak column, static axial load 1120 kN on the centre column, to get the tendon capacity to assume positive and negative bending moments due to lateral load, according to provisions of ACI 318-2008 part 21.5.2.5 (c. Test results showed that the moment tendon contribution on beam section, in the tensile area, the positive and negative moment both on the left side or the right side column are all qualified ( 25 %. As for the negative moment, either left or right side column are all qualified (4.0. Although the contribution of positive moment capacity tendon in compression areas does not qualify, in overall, the reliability and ductility of the structure qualify.
Institute of Scientific and Technical Information of China (English)
郭东升; 贾艳敏; 陶永靖
2014-01-01
Based on an actual bridge as the project background,did the hollow slab single static test,establishing the finite element model of hol-low plate beam by Midas Civil,simulation of single beam static loading process,analysis of deflection and stress of the beam,the results show that the hollow plate beam’s deflection meet design and use requirements,the stress state was reasonable,the stress variation along the beam high linear under the static test load,structure is safe.%以实桥为工程依托，进行了空心板单梁试验，并应用Midas Civil有限元软件建立空心板单梁模型，模拟单梁静力加载过程，对比分析空心板梁挠度及控制截面应力，结果表明：空心板梁在试验静力荷载作用下，挠度满足设计使用要求，应力状态合理，沿梁高线性变化，空心板梁受力安全。
Holographic motion picture camera with Doppler shift compensation
Kurtz, R. L. (Inventor)
1976-01-01
A holographic motion picture camera is reported for producing three dimensional images by employing an elliptical optical system. There is provided in one of the beam paths (the object or reference beam path) a motion compensator which enables the camera to photograph faster moving objects.
Institute of Scientific and Technical Information of China (English)
韩全吉; 王守恒; 朱海堂; 高丹盈; 崔海波
2014-01-01
为了研究经历长期持荷后的玄武岩纤维增强聚合物（ BFRP）筋钢纤维高强混凝土梁在重复荷载作用下的变形性能，进行了7根BFRP筋钢纤维高强混凝土梁的受弯试验，分析BFRP筋配筋率、钢纤维体积率以及加载水平等因素对梁的变形性能的影响。结果表明：经过10次卸载、加载循环后，受力BFRP筋与混凝土之间的黏结性能没有发生退化；荷载水平、钢纤维掺量及BFRP筋配筋率对BFRP筋钢纤维高强混凝土梁的加载-卸载挠度曲线及挠度恢复能力有不同程度的影响；BFRP筋钢纤维高强混凝土梁具有较高的变形恢复能力和良好的抗重复荷载性能。%In order to study the deformation performance of steel fiber reinforced high-strength concrete beams with BFRP rebars, the bending test of 7 beams under repeated load after suffering long-term sustaining load were carried out.The effects of reinforcement ratio of BFRP bars , fraction of steel fiber by volume and loading level on deformation performance of beams were analyzed .The results shown that the bonding behavior between BFRP rebars and concrete is not degradative after 10 loading-unloading cycles;the factors,including loading level , the dosage of steel fiber and the reinforcement ratio of BFRP , express the different levels of influence on the load-deflection curve and the deflection recovery capability of test beams;and steel fiber reinforced high-strength concrete beams with BFRP rebars possess higher deflection recovery capability and better repeated load resistance .
Institute of Scientific and Technical Information of China (English)
王森; 魏琏; 韦承基
2001-01-01
本文通过三榀转换梁的试验研究，对高层建筑转换梁结构的截面选择、配筋设计以及钢筋端部锚固构造要求等进行了分析。研究表明，满跨转换梁与上部墙体有共同作用，转换梁抗弯抗剪承载力以及墙板的抗翦承载力均有相当的安全度，最终破坏发生在墙体底部局部压坏。不满跨转换梁的试验结果表明，无墙体部位转换梁的抗剪决定着整个转换结构的承载能力，上部有墙体部位墙梁有共同作用，应按有限元法计算内力，并进行配筋设计。%based on the experimental research of three transfer beam models, this paper analyses the determination of sections,reinforcing methods and anchoring of bars at the beam end of transfer beams in highrise buildings. The experimental results of full span wall on transfer beam show that there is interaction between the beam and the shear walls above.The flexural capacity of beam and shear capacity of both beam and the wall above is quite sufficent while the ultimate destruction arises from local pressure failure at the bottom of shear wall near the column.The experimental results and analytical results by finite element method of partial span wall on transfer beam show that the shear capactiy of the partial transfer beam without shear wall above detemines the loading capactiy of whole transfer structure, and there is joint action between structural wall on the transfer beam and the beam itself,which should be designed with the finite element method.
Cooperation, compensation and transition
Ju, Y.
2004-01-01
Cooperation and compensation are two important and well-linked issues in economics. The central question in cooperation is how to share the joint gains among participating players. Compensation is a specific aspect of surplus sharing problems providing incentives for agents to sacrifice their own di
Medical leadership compensation framework
Uhlíř, Tomáš
2009-01-01
This master thesis deals with outlining the rationale of redesigning medical leadership compensation framework within Interior Health Authority (IH). In particular, reviews IH's organizational structure, analyses job descriptions for medical leaders, recommends improvements of communication flow across the authority and designs medical leader's compensation model.
Hybrid compensation arrangement in dispersed generation systems
DEFF Research Database (Denmark)
Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim
2005-01-01
This paper presents a hybrid compensation system consisting of an active filter and distributed passive filters. In the system, each individual passive filter is connected to a distortion source and designed to eliminate main harmonics and supply reactive power for the distortion source, while...... are performed for a power system including the dispersed generation units connected into the system through power electronic converters and diode rectifier loads, which produce the distorted waveforms. The simulation results have demonstrated that good compensation effects can be achieved by using the combined...
Beam-beam simulation code BBSIM for particle accelerators
Energy Technology Data Exchange (ETDEWEB)
Kim, Hyung J.; Sen, Tanaji; /Fermilab
2011-01-01
A highly efficient, fully parallelized, six-dimensional tracking model for simulating interactions of colliding hadron beams in high energy ring colliders and simulating schemes for mitigating their effects is described. The model uses the weak-strong approximation for calculating the head-on interactions when the test beam has lower intensity than the other beam, a look-up table for the efficient calculation of long-range beam-beam forces, and a self-consistent Poisson solver when both beams have comparable intensities. A performance test of the model in a parallel environment is presented. The code is used to calculate beam emittance and beam loss in the Tevatron at Fermilab and compared with measurements. They also present results from the studies of stwo schemes proposed to compensate the beam-beam interactions: (a) the compensation of long-range interactions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at CERN with a current carrying wire, (b) the use of a low energy electron beam to compensate the head-on interactions in RHIC.
Institute of Scientific and Technical Information of China (English)
葛若东; 刘茂军; 赵艳林
2011-01-01
对常用的几种Kaiser点确定方法进行了比较分析,从参数的选用、判断方法等方面指出了各方法的优点及不足之处.通过对钢筋混凝土梁进行循环加载试验,分析各级荷载下的AE累积计数N与荷载F关联曲线的特点,发现在lnN-F半对数坐标上,关联曲线的拐点坐标具有明显的变化规律,可作为钢筋混凝土梁循环加载时的Kaiser点；提出了用求解曲线拐点来确定Kaiser点的方法,并利用该方法对钢筋混凝土梁受荷过程的Felicity效应进行了分析.%Several methods of determining the Kaiser point are compared. Three reinforced concrete beams are cyclic loaded,and the characteristics of the N - F curves at each load levels are analyzed. It is found that the inflection points of the N - F curves in the semi-logarithmic coordinate system (In N - F) have obvious regularity, and the inflection points can be used as the Kaiser point when the reinforced concrete beams are cyclic loaded. A new method of determining Kaiser point by calculating the inflection points is proposed and the Felicity effective of reinforced concrete beams in cyclic loading is discussed.
Turbulence compensation: an overview
van Eekeren, Adam W. M.; Schutte, Klamer; Dijk, Judith; Schwering, Piet B. W.; van Iersel, Miranda; Doelman, Niek J.
2012-06-01
In general, long range visual detection, recognition and identification are hampered by turbulence caused by atmospheric conditions. Much research has been devoted to the field of turbulence compensation. One of the main advantages of turbulence compensation is that it enables visual identification over larger distances. In many (military) scenarios this is of crucial importance. In this paper we give an overview of several software and hardware approaches to compensate for the visual artifacts caused by turbulence. These approaches are very diverse and range from the use of dedicated hardware, such as adaptive optics, to the use of software methods, such as deconvolution and lucky imaging. For each approach the pros and cons are given and it is indicated for which scenario this approach is useful. In more detail we describe the turbulence compensation methods TNO has developed in the last years and place them in the context of the different turbulence compensation approaches and TNO's turbulence compensation roadmap. Furthermore we look forward and indicate the upcoming challenges in the field of turbulence compensation.
Institute of Scientific and Technical Information of China (English)
罗素蓉; 吴文达; 陈彪
2015-01-01
In order to simulate the real load-carrying capability of strengthened components in practical engineering,the original concrete components were strengthened and cured with self-compacting concrete while continuously under load.Flexural testing was carried out on 7 RC beams strengthened with self-compacting concrete under secondary load and 2 beams without strengthening.Different initial forces,different strengthening thicknesses and different methods of interface treatment were studied to find the corresponding effects on the flexural capacity and section stiffness of the strengthened beams.Crack distribution patterns,load-deflection curves and development law of steel strain were measured in the test.The results show that strengthening RC beams with self-compacting concrete can significantly improve the flexural capacity,section stiffness,and crack resistance of the RC beams.The flexural capacity of the RC beams strengthened with self-compacting concrete under secondary load was reduced with the increase of the initial load.Based on the test results and the plane section assumption,formulae predicting the lagged strain and the flexural capacity of the beams strengthened by self-compacting concrete were proposed,and the calculation results were in good agreement with the test results.%为模拟实际工程中加固构件的真实承载能力,实验在原混凝土构件持续受荷状态下,采用自密实混凝土对构件进行加固、养护.共进行了7根二次受力下自密实混凝土加固钢筋混凝土梁和2根对比梁的受弯性能试验,研究了不同初始受力水平、不同加固厚度及不同界面处理方式对加固钢筋混凝土梁抗弯承载力和截面刚度的影响.试验量测了构件裂缝分布形态、荷载-挠度曲线、钢筋应变发展规律等.结果表明:采用自密实混凝土加固钢筋混凝土梁,能有效地提高钢筋混凝土梁的抗弯承载力、截面刚度等性能;二次受力下自密实混凝土加
Compensator thickness verification using an a-Si EPID
International Nuclear Information System (INIS)
Electronic portal imaging devices (EPIDs) are being increasingly employed to make therapy verification and dose measurements in the clinic. In this work, we investigate the use of an amorphous silicon (a-Si) EPID to verify the accuracy of compensator fabrication and mounting. Compensator thickness estimates on a two-dimensional grid were calculated from the primary component of transmission obtained by subtracting a modeled scatter component from the total transmission measured with the EPID. The primary component was related to the thickness via an exponential relation that includes beam hardening. Implementation of the method involved determination of: (i) a calibration curve relating EPID pixel values to energy fluence for open and attenuated fields, which was found to be linear for open fields but to have a small quadratic component for attenuated beams; (ii) EPID scatter factors to account for field size effects, which exhibited a small dependence on compensator thickness and field size; (iii) the attenuation coefficient of the steel shot compensator material, which varied slightly with off-axis distance and field size, and (iv) an analytical model to predict scatter from the compensator, which was calculated to be <4% at the standard EPID imaging distance of 140 cm. Thickness distributions were then measured for several types of attenuators including flat, test, and clinical compensators. Although uncertainties associated with compensator manufacturing were non-negligible and made assessment of thickness measurement uncertainty difficult, we estimate the latter to be ∼0.5 mm for steel shot compensators of thickness <4 cm
Institute of Scientific and Technical Information of China (English)
高鹏; 顾祥林
2009-01-01
According to the characteristic of pre-loaded reinforced concrete beams strengthened by pre-tensioned carbon fiber composite sheets, a suitable finite element model and corresponding calculation steps were proposed. The method was verified by the testing results of two groups of strengthened beam specimens. Comparison between simulation and testing results shows that the proposed method is a precise numerical tool. Further parameter analysis using the proposed method shows that the bearing capacity of a strengthened beam might be notably reduced if the pre-load applied on the beam is larger than 40% of the initial bearing capacity of the beam, the strength of carbon fiber composite sheets can be fully used by using pre-tensioning technique,and the negative influence of the pre-load on the bending behavior of a strengthened beam can be made up when the pre-strain of carbon fiber composite sheets is between 0.003～0.004.%根据预张拉碳纤维布加固持荷钢筋混凝土梁受力特点,采用商业软件建立有限元模型对梁加固和受荷全过程进行模拟和分析.对两组试验梁的模拟计算结果显示,有限元方法有较好的精度.试验和进一步的有限元数值模拟分析结果表明,当构件上的持荷水平超过未加固构件承载力的40%时,持荷会降低加固构件的承载力;采用预张拉加固方法可充分发挥碳纤维布的强度,当碳纤维布中的有效预拉应变达0.003～0.004时,可消除持荷对加固梁受力性能的影响.
Institute of Scientific and Technical Information of China (English)
周勇超; 郝宪武
2012-01-01
Based on load test of concrete simply supported T-beam bridge reinforced by CFRP in service, the cross-section stress and stiffness in serviceability stage are analyzed in this paper. The results show that CFRP can be coordination with concrete and the carrying capacity of concrete simply supported T-beam is increased by about 45.3% , the stiffness is increased by about 52.7%. Considering the second force, the calculation methods of cross-section stress and stiffness of T-beam in serviceability stage are derived, the calculations are consistent with load test results.%通过对利用CFRP加固的在役钢筋混凝土简支T梁桥荷载试验,研究了正常使用状态下的截面应力、刚度,证明CFRP能够与混凝土协调工作,对在役混凝土简支T梁的承载力提高幅度约为45.3％,刚度提高幅度约为52.7％.在考虑二次受力的基础上,推导了在正常使用状态下,CFRP加固混凝土简支T梁截面应力、短期刚度的计算方法,计算结果与实测结果吻合良好.
García Canseco, Eloísa; Griñó Cubero, Robert; Ortega, Romeo; Salichs Vivancos, Miguel; Stankovic, Alexander
2007-01-01
This article advances an analysis and compensator design framework for power-factor compensation based on cyclodissipativity. Although the framework applies to general polyphase unbalanced circuits, this paper have focused on the problem of power factor compensation with LTI capacitors or inductors of single-phase loads. The full power of the approach are expected to become evident for polyphase unbalanced loads with possibly nonlinear lossless compensators, where the existing solutions are f...
Electronic compensation technique to deliver a total body dose
Lakeman, Tara E.
Purpose: Total body irradiation (TBI) uses large parallel-opposed radiation fields to suppress the patient's immune system and eradicate the residual cancer cells in preparation of recipient for bone marrow transplant. The manual placement of lead compensators has been conventionally used to compensate for the varying thickness throughout the body in large-field TBI. The goal of this study is to pursue utilizing the modern electronic compensation technique to more accurately and efficiently deliver dose to patients in need of TBI. Method: Treatment plans utilizing the electronic compensation to deliver a total body dose were created retrospectively for patients for whom CT data had been previously acquired. Each treatment plan includes two pair of parallel opposed fields. One pair of large fields is used to encompass the majority of the patient's anatomy. The other pair are very small open fields focused only on the thin bottom portion of the patient's anatomy, which requires much less radiation than the rest of the body to reach 100% of the prescribed dose. A desirable fluence pattern was manually painted within each of the larger fields for each patient to provide a more uniform distribution. Results: Dose-volume histograms (DVH) were calculated for evaluating the electronic compensation technique. In the electronically compensated plans, the maximum body doses calculated from the DVH were reduced from the conventionally-compensated plans by an average of 15%, indicating a more uniform dose. The mean body doses calculated from the electronically compensated DVH remained comparable to that of the conventionally-compensated plans, indicating an accurate delivery of the prescription dose using electronic compensation. All calculated monitor units were within clinically acceptable limits. Conclusion: Electronic compensation technique for TBI will not increase the beam on time beyond clinically acceptable limits while it can substantially reduce the compensator setup
Adaptive Compensation of Reactive Power With Shunt Active Power Filters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Asiminoaei, Lucian; Hansen, Steffan;
2008-01-01
This paper describes an adaptive method for compensating the reactive power with an active power filter (APF), which is initially rated for mitigation of only the harmonic currents given by a nonlinear industrial load. It is proven that, if the harmonic currents do not load the APF at the rated...
INDUSTRIAL RESEARCH INTO HIGH HARMONIC INFLUENCE ON COMPENSATION DEVICES
Directory of Open Access Journals (Sweden)
Y.E. Shklyarskiy
2013-02-01
Full Text Available This work introduces the structure of a reactive power compensation system under high harmonics arising from both external nonlinear load and internal nonlinear load of an industrial enterprise. The efficiency of the system parameters definition algorithm in the presence of high harmonics is verified with experimental research at an industrial enterprise.
Institute of Scientific and Technical Information of China (English)
杨涛; 薛伟辰
2012-01-01
基于3根模型梁试件的单调静力试验,对体外预应力钢-混凝土组合梁的受力性能进行了研究.研究表明:施加体外预应力可以有效提高组合梁的抗弯承载力,但试件的延性有所降低；试件纯弯段截面应变分布符合平截面假定；增大栓钉间距可以提高试件的极限变形能力,但对其抗弯承载力的影响不大；试件的抗剪连接程度越低,达到极限荷载时栓钉滑移值越大.结合试验并通过有限元建模,分析了混凝土强度等级、有效预应力、预应力筋线型、栓钉间距等对体外预应力组合梁受力性能的影响.最后,在考虑了预应力筋作用的基础上,提出了体外预应力组合梁抗弯承载力的简化计算方法,该方法可为体外预应力组合梁的设计计算提供参考.%According to the monotonic loading experiment of three specimens, the static behavior of steel-concrete composite beams prestressed with external tendons was investigated. The results show that adding prestressing with external tendons can effectively improve the bending capacity of composite beams with reduced ductility at the same time. Strain distribution at the cross section in pure flexure zone remains approximately linear. Increasing the spacing of studs welded on steel beams can improve ultimate deformability of prestressed beams with slight effect on bending capacity. With the decrease of shear connection degree, the slip of studs increases at ultimate load. According to different finite element models of composite beams prestressed with external tendons, the effects of concrete compressive strengthen, effective prestress, external tendons profile and studs spacing on the static behavior of composite beams were discussed. A simplified calculation method of bending capacity was proposed based on prestress effect to provide references for the design and calculation of composite beams prestressed with external tendons.
Institute of Scientific and Technical Information of China (English)
赵军; 马鑫; 高丹盈
2012-01-01
The experiment was carried out on the shear performance of 5 steel fiber reinforced concrete coupling beams and 1 common reinforced concrete coupling beam under low cyclic load. The effects of steel fibers on the cracks and failure modes of reinforced concrete coupling beams were studied. The changing laws of diagonal section bearing capacity of steel fiber reinforced concrete coupling beams with mixed fiber content were analyzed. Based on the calculating method for the diagonal section bearing capacity of common reinforced concrete coupling beam, the calculating method for the diagonal section bearing capacity of reinforced concrete coupling beam with steel fibers was put forward. Comparative results show that the calculated values agree well with test ones.%通过低周反复荷载下5个钢筋钢纤维混凝土连梁和1个普通钢筋混凝土连梁的抗剪性能试验,研究了钢纤维对钢筋混凝土连梁裂缝和破坏形态的影响,探讨了钢筋钢纤维混凝土连梁的斜截面承载力随钢纤维掺量的变化规律,结合普通钢筋混凝土连梁斜截面承载力的计算方法,提出了钢筋钢纤维混凝土连梁斜截面承载力的计算公式,比较结果表明,计算值和试验值吻合较好.
Climate change and compensation
DEFF Research Database (Denmark)
Jensen, Karsten Klint; Flanagan, Tine Bech
2013-01-01
This paper presents a case for compensation of actual harm from climate change in the poorest countries. First, it is shown that climate change threatens to reverse the fight to eradicate poverty. Secondly, it is shown how the problems raised in the literature for compensation to some extent...... are based on misconceptions and do not apply to compensation of present actual harm. Finally, two arguments are presented to the effect that, in so far as developed countries accept a major commitment to mitigate climate change, they should also accept a commitment to address or compensate actual harm from...... climate change. The first argument appeals to the principle that if it is an injustice to cause risk of incurring harm in the future, then it is also an injustice to cause a similar harm now. The second argument appeals to the principle that if there is moral reason to reduce the risk of specific harms...
Coney, Thom A.
1996-01-01
Performance status of the Adaptive Rain Fade Compensation includes: (1) The rain fade protocol is functional detecting fades, providing an additional 10 dB of margin and seamless transitions to and from coded operation; (2) The stabilization of the link margins and the optimization of rain fade decision thresholds has resulted in improved BER performance; (3) Characterization of the fade compensation algorithm is ongoing.
Optimal Sales Force Compensation
Matthias Kräkel; Anja Schöttner
2014-01-01
We analyze a dynamic moral-hazard model to derive optimal sales force compensation plans without imposing any ad hoc restrictions on the class of feasible incentive contracts. We explain when the compensation plans that are most common in practice - fixed salaries, quota-based bonuses, commissions, or a combination thereof - are optimal. Fixed salaries are optimal for small revenue-cost ratios. Quota-based bonuses (commissions) should be used if the revenue-cost ratio takes intermediate (larg...
Essays in Executive Compensation
Zhang, Dan
2013-01-01
This doctoral thesis is made of three empirical research papers focused on executive compensation topics. The first chapter is a solo paper, while the second and third papers are co-authored with Antonio Parbonetti. The first chapter answers to Bushman and Smith’s (2001) call for research on compensation of executives other than CEOs. Specifically, using a sample of 586 firm-year observations over the period 2000-2009, I investigate the economic determinants and effects on shareholder va...
Large Capacity SMES for Voltage Dip Compensation
Iwatani, Yu; Saito, Fusao; Ito, Toshinobu; Shimada, Mamoru; Ishida, Satoshi; Shimanuki, Yoshio
Voltage dips of power grids due to thunderbolts, snow damage, and so on, cause serious damage to production lines of precision instruments, for example, semiconductors. In recent years, in order to solve this problem, uninterruptible power supply systems (UPS) are used. UPS, however, has small capacity, so a great number of UPS are needed in large factories. Therefore, we have manufactured the superconducting magnetic energy storage (SMES) system for voltage dip compensation able to protect loads with large capacity collectively. SMES has advantages such as space conservation, long lifetime and others. In field tests, cooperating with CHUBU Electric Power Co., Inc. we proved that SMES is valuable for compensating voltage dips. Since 2007, 10MVA SMES improved from field test machines has been running in a domestic liquid crystal display plant, and in 2008, it protected plant loads from a number of voltage dips. In this paper, we report the action principle and components of the improved SMES for voltage dip compensation, and examples of waveforms when 10MVA SMES compensated voltage dips.
Institute of Scientific and Technical Information of China (English)
杨金花; 张鹏君
2015-01-01
By employing linear strain and utilizing piezoelectric theory including thermal effects,the constitutive relations of the piezoelectric beam reinforced with BNNTs are es-tablished.The buckling governing equations of the structure are derived through variational principle.In numerical examples,the effects of voltage,temperature,boundary condition and volume fraction on the buckling load of piezoelectric beam reinforced with BNNTs are discussed in detail.The following conclusions may be drawn from the present work:apply-ing negative and positive voltage to BNNT leads to increase and decrease of the buckling load.The buckling load of piezoelectric beam reinforced with BNNTs increases with the de-crease of temperature,and also increases when the volume fraction of BNNT in matrix in-creases.%运用线性应变几何关系及考虑温度效应的压电理论，建立了 BNNTs 增强压电梁的本构关系，通过变分推导出了结构的屈曲控制方程。算例中详细讨论了电压、温度、边界条件及体积比对 BNNTs 增强压电梁屈曲载荷的影响。研究结果表明，在 BNNTs 两端施加负或正电压可使压电梁的屈曲载荷增加或减小；BNNTs 增强压电梁的屈曲载荷随着温度的降低以及硼氮纳米管所占体积比的增加而增大。
Beam-beam observations in the Relativistic Heavy Ion Collider
Energy Technology Data Exchange (ETDEWEB)
Luo, Y. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Laboratory (BNL), Upton, NY (United States); White, S. [Brookhaven National Laboratory (BNL), Upton, NY (United States)
2015-06-24
The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced β*s at the interaction points, the maximum peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we first present the beam-beam observations in the previous RHIC polarized proton runs. Then we analyze the mechanisms for the beam loss and emittance growth in the presence of beam-beam interaction. The operational challenges and limitations imposed by beam-beam interaction and their remedies are also presented. In the end, we briefly introduce head-on beam-beam compensation with electron lenses in RHIC.
A Novel Wireless and Temperature-Compensated SAW Vibration Sensor
Wen Wang; Xufeng Xue; Yangqing Huang; Xinlu Liu
2014-01-01
A novel wireless and passive surface acoustic wave (SAW) based temperature-compensated vibration sensor utilizing a flexible Y-cut quartz cantilever beam with a relatively substantial proof mass and two one-port resonators is developed. One resonator acts as the sensing device adjacent to the clamped end for maximum strain sensitivity, and the other one is used as the reference located on clamped end for temperature compensation for vibration sensor through the differential approach. Vibrati...
Robotic motion compensation for applications in radiation oncology
Energy Technology Data Exchange (ETDEWEB)
Herrmann, Christian
2013-07-22
Radiation therapy today, on account of improvements in treatment procedures over the last 60 years, allows precise treatment of static tumors inside the human body. However, irradiation of moving tumors is still a challenging task as moving tumors often leave the treatment beam and the radiation dose delivered to the tumor reduces simultaneously increasing that on healthy tissue. This research work aims to push the frontiers of radiation therapy in order to enable precise treatment of moving tumors with focus on research and development of a unique real-time system enabling active motion compensation through robotic means to compensate tumor motion. During treatment, patients lie on a treatment couch which is normally used for static position corrections of patient set-up errors prior to radiation treatment. The treatment couch used, called HexaPOD, is a parallel manipulator with six degrees of freedom which can precisely position heavy loads inside a small region. Despite the HexaPOD not initially built with dynamics in mind, it is used in this work for sustained motion compensation by moving patients such that tumors stay precisely located at the center of the treatment beam during the complete course of treatment. In order to realize real-time tumor motion compensation by means of the HexaPOD, several challenges need to be addressed. Real-time aspects are covered by the adoption of a hard real-time operation system in combination with measurement and estimation of latencies of all physical quantities in the compensation system such as tumor or breathing position measurements. Accurate timing information is respected consistently in the whole system and all software-induced latencies are adaptively compensated for. This requires knowledge of future tumor positions from predictors. Several predictors for breathing and tumor motion predictions are proposed and evaluated in terms of a variety of different performance metrics. Extensions to prediction algorithms are
Institute of Scientific and Technical Information of China (English)
李慧乐; 夏禾; 郭薇薇
2013-01-01
The theoretical solution for the vibration of simply-supported beams under moving load series is derived.Based on the solution,the train speeds inducing resonance and two types of cancellation for simply-supported beams are obtained,and the occurrence mechanisms of resonance and vibration cancellation phenomena are clarified.It is demonstrated that there are two types of vibration cancellation effect for simply-supported beams under moving load series:the first cancellation related to a single load behavior,and the second related to the distances between moving forces.When cancellation occurs,the free vibrations after the moving loads depart from the bridge are counterbalanced to null,thus the bridge response becomes smaller.The condition of cancellation is more decisive than that of resonance.When the train speeds meet conditions of both phenomena,cancellation plays a predominant role,and resonance disappearance can be expected.Theoretically,the phenomenon of resonance can be avoided by adjusting the length ratio between a vehicle and a bridge.The dynamic responses of two simply-supported beams are analyzed in the case study,which verify the validity of the theoretical analysis.%推导了简支梁在移动荷载列作用下的振动响应理论解,得到了简支梁发生共振及两类消振效应的车速计算公式,阐明了二者的发生机理.提出移动荷载作用下简支梁存在两类消振效应,第一类消振为单个荷载行为,第二类消振与荷载间距有关；发生消振效应时,已经离开桥梁的荷载所引起简支梁的自由振动抵消为零,桥梁的动力响应较小;消振发生的条件较共振更为严格,当车速同时满足二者的要求时,消振效应起主要作用,将出现共振消失现象；理论上通过调整车厢长与桥跨之比可避免共振现象发生.通过算例分析了两座简支梁在列车过桥时的动力响应,验证了理论分析的正确性.
A slow gravity compensated atom laser
DEFF Research Database (Denmark)
Kleine Büning, G.; Will, J.; Ertmer, W.;
2010-01-01
We report on a slow guided atom laser beam outcoupled from a Bose–Einstein condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser beam can be controlled by compensating the gravitational acceleration and we reach residual accelerations as low as 0.0027 g. The outcoupling...... mechanism allows for the production of a constant flux of 4.5×106 atoms per second and due to transverse guiding we obtain an upper limit for the mean beam width of 4.6 μm. The transverse velocity spread is only 0.2 mm/s and thus an upper limit for the beam quality parameter is M 2=2.5. We demonstrate...... the potential of the long interrogation times available with this atom laser beam by measuring the trap frequency in a single measurement. The small beam width together with the long evolution and interrogation time makes this atom laser beam a promising tool for continuous interferometric measurements....
Voltage holding study of 1 MeV accelerator for ITER neutral beam injector.
Taniguchi, M; Kashiwagi, M; Umeda, N; Dairaku, M; Takemoto, J; Tobari, H; Tsuchida, K; Yamanaka, H; Watanabe, K; Kojima, A; Hanada, M; Sakamoto, K; Inoue, T
2012-02-01
Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of that of ideal quasi-Rogowski electrode. It was suggested that the emission of the clumps is enhanced by a local electric field concentration, which leads to discharge initiation at lower voltage. To reduce the electric field concentration in the MeV accelerator, gaps between the grid supports were expanded and curvature radii at the support corners were increased. After the modifications, the accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. However, the beam energy was still limited at a level of 900 keV with a beam current density of 150 A∕m(2) (346 mA) where the 3 × 5 apertures were used. Measurement of the beam profile revealed that deflection of the H(-) ions was large and a part of the H(-) ions was intercepted at the acceleration grid. This causes high heat load on the grids and the breakdowns during beam acceleration. To suppress the direct interception, new grid system was designed with proper aperture displacement based on a 3D beam trajectory analysis. As the result, the beam deflection was compensated and the voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A∕m(2) (427 mA), which is close to the requirement of ITER accelerator (1 MeV, 200 A∕m(2)).
Compensation committee composition and CEO compensation – Finnish evidence
Uusitalo, Mikael
2012-01-01
PURPOSE OF THE STUDY The purpose of this study is to examine the effect of compensation committee composition on the level of CEO compensation. The composition of the compensation committee is analyzed by using five variables which are: 1) the proportion of non-independent directors, 2) the proportion of long-serving directors, 3) the proportion of CEO-directors, 4) the proportion of busy directors and 5) the presence of a blockholder on the compensation committee. CEO compensation is measure...
Institute of Scientific and Technical Information of China (English)
郭莹; 姚勇
2011-01-01
为了解德阳市王官村互通式立交桥在荷载作用下的实际工作状态,对该桥梁进行了静动荷载试验.试验首先基于通用有限元程序软件进行理论计算,并根据理论计算结果作为控制因素进行现场检测试验,并对检测过程及该桥使用状况进行总结分析.试验结果表明,该桥使用性能较好,处于弹性工作状态,承载能力满足有关规范的要求.%To understand the real work condition of interoperability overpass continuous beam in Wangguan Village of Deyang on the loading, the static/dynamic load tests have been carried out. We firstly computed the theory consequence based on the procedure software in general, and then actually tested the bridge by comparing with the theory effect. There are some reasonable analysis about the loading procedure and the back use. The result shows that usage function of approach structure is better,the loading ability satisfy with the request of our country normative.
Numerical Analysis of Parasitic Crossing Compensation with Wires in DA$\\Phi$NE
Energy Technology Data Exchange (ETDEWEB)
Valishev, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Shatilov, D. [Russian Academy of Sciences (RAS), Novosibirsk (Russian Federation). Budker Inst. of Nuclear Physics (BINP); Milardi, C. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LNF); Zobov, M. [National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati (INFN-LNF)
2015-06-24
Current-bearing wire compensators were successfully used in the 2005-2006 run of the DAΦNE collider to mitigate the detrimental effects of parasitic beam-beam interactions. A marked improvement of the positron beam lifetime was observed in machine operation with the KLOE detector. In view of the possible application of wire beam-beam compensators for the High Luminosity LHC upgrade, we revisit the DAΦNE experiments. We use an improved model of the accelerator with the goal to validate the modern simulation tools and provide valuable input for the LHC upgrade project.
Numerical analysis of parasitic crossing compensation with wires in DA$\\Phi$NE
Valishev, A; Milardi, C; Zobov, M
2015-01-01
Current bearing wire compensators were successfully used in the 2005-2006 run of the DA{\\Phi}NE collider to mitigate the detrimental effects of parasitic beam-beam interactions. A marked improvement of the positron beam lifetime was observed in machine operation with the KLOE detector. In view of the possible application of wire beam-beam compensators for the High Luminosity LHC upgrade, we revisit the DA{\\Phi}NE experiments. We use an improved model of the accelerator with the goal to validate the modern simulation tools and provide valuable input for the LHC upgrade project.
Stealth Compensation Via Retirement Benefits
Lucian Arye Bebchuk; Fried, Jesse M.
2004-01-01
This paper analyzes an important form of "stealth compensation" provided to managers of public companies. We show how boards have been able to camouflage large amount of executive compensation through the use of retirement benefits and payments. Our study highlights the significant role that camouflage and stealth compensation play in the design of compensation arrangements. Our study also highlights the significance of whether information about compensation arrangements is not merely publicl...
Design and Analysis Methodologies for Inflated Beams
Veldman, S.L.
2005-01-01
The central theme of the thesis is bending behaviour of inflated beams. Three different types of beams have been analysed for the bending load case: a straight cylindrical beam made of anisotropic foil material, a conical beam made of an isotropic foil material, and a carbon fibre braided beam. The
Energy Technology Data Exchange (ETDEWEB)
Zholents, A.
1994-12-01
The term beam-beam effects is usually used to designate different phenomena associated with interactions of counter-rotating beams in storage rings. Typically, the authors speak about beam-beam effects when such interactions lead to an increase of the beam core size or to a reduction of the beam lifetime or to a growth of particle`s population in the beam halo and a correspondent increase of the background. Although observations of beam-beam effects are very similar in most storage rings, it is very likely that every particular case is largely unique and machine-dependent. This constitutes one of the problems in studying the beam-beam effects, because the experimental results are often obtained without characterizing a machine at the time of the experiment. Such machine parameters as a dynamic aperture, tune dependencies on amplitude of particle oscillations and energy, betatron phase advance between the interaction points and some others are not well known, thus making later analysis uncertain. The authors begin their discussion with demonstrations that beam-beam effects are closely related to non linear resonances. Then, they will show that a non linearity of the space charge field is responsible for the excitation of these resonances. After that, they will consider how beam-beam effects could be intensified by machine imperfections. Then, they will discuss a leading mechanism for the formation of the beam halo and will describe a new technique for beam tails and lifetime simulations. They will finish with a brief discussion of the coherent beam-beam effects.
A Novel Frequency Compensation Technique for Three-Stage Amplifier
Institute of Scientific and Technical Information of China (English)
LI Qiang; YI Jun; LI Zhao-ji; ZHANG Bo; FANG Jian; LUO Ping
2005-01-01
A novel frequency compensation technique for three-stage amplifier with dual complex pole-zero (DCP) cancellation is proposed. It uses one pair of complex zeros to cancel one pair of complex poles, resulting in feature that frequency response of the three-stage amplifier exhibits that of a single-pole system. Thus the gain-bandwidth (GBW) is expected to be increased several times compared to the conventional nested miller compensation (NMC) approach. Moreover, this technique requires only one very small compensation capacitor even when driving a big load capacitor. A GBW 4.63 MHz, DC gain 100 dB, PM 90o and power dissipation 0.87 mW can be achieved for a load capacitor 100 pF with a single Miller compensation capacitor 2 pF at a ±1V supply in a standard 0.6-μm CMOS technology.
Compensation for nuclear damage
International Nuclear Information System (INIS)
To secure fair and efficient compensation for damage likely to be caused by the utilisation of nuclear energy, a special civil liability regime was set up by several international conventions. Three of these conventions are in force and Spain is a Contracting Party to all three. The principles established in the first instance at European level by the Paris Convention (absolute and exclusive liability of the nuclear operator, limitation of such liability, compulsory insurance...) are intended to guarantee that possible victims of a nuclear incident will obtain compensation for damage suffered. The Brussels Convention Supplementary to the Paris Convention provides for official funds to compensate victims through intervention by the Contracting Parties. Each Contracting Party should implement these Conventions at national level by appropriate legislation, which is what Spain did with its Act on Nuclear Energy of 29th April 1964, as supplemented in 1967 by the Regulations on Cover for Nuclear Hazards. (N.E.A.)
Institute of Scientific and Technical Information of China (English)
张建新; 李辉; 李青宁
2015-01-01
采用数理统计的方法,通过对收集到的国内外集中荷载作用的钢筋混凝土无腹筋简支梁的大量试验数据进行回归分析,对无腹筋简支梁受剪承载力的主要影响因素综合加以考虑,通过引入纵筋率及截面高度综合影响参数,提出无腹筋简支梁抗剪承载力实用计算公式,并把利用该式得到的相应计算值与试验数据进行比较. 研究表明,本文所建议的计算公式与试验结果有较好的吻合度且偏于安全,基本可以应用于实际工程.%To evaluate the shear bearing capacity of reinforced concrete composite beams,the accurate calcutation formulas are needed. On the basis of available testing data of simply supported reinforced concrete beams without web reinforcement under two-point concentrated load,the effects of concrete strength,the shear-span to depth ratio,and the reinforcement ratio of longitudinal reinforcing bar on the shear resistance of reinforced concrete beams subject to concentrated load are reinvestigated. Researches are shown that through leading into comprehensive influence parameter of longitudinal reinforcement ratio and the high of beam, the formulas are proposed to calculate the shear bearing capacity of reinforced concrete beams without web reinforcement, which are simple, in better agreement with a large number of the experimental data. At the same time,compare the shear design equations of China design code of reinforced concrete structures, the credibility contain very big exaltation. Therefore, that formula is available for the extensive applicability.
Institute of Scientific and Technical Information of China (English)
钟春玲; 叶增; 张云龙
2012-01-01
In the prestressed concrete bridge reinforcement, the application of the external prestressed gradually widely. This paper mainly based on differential equation deduced the external prestressed continuous beam in the vertical concentrated load dint method, the analytical solution of the equation. Using this theory calculation in the vertical deflection under concentrated load along the beam long distribution curve and Ansys numerical analysis re- suits are compared, and both have good consistency, it is shown that the result is reasonable and credible. Contrast the result indicates that the analytical solution and can get in the normal service condition the deflection of the con- crete beams, for the future analysis of the external prestressed carbon fiber reinforced the continuous girder provides the foundation.%在预应力混凝土桥梁加固中,体外预应力的应用逐渐广泛.本文主要基于微分方程,推导了体外预应力连续梁在竖向集中荷载作用下力法方程的解析解.利用该理论,计算了在竖向集中荷载作用下的挠度沿梁长的分布曲线,并与Ansys数值分析结果进行了对比,二者具有较好的一致性,说明该计算结果是合理的,可信的.对比结果表明,采用该解析解并能够得到在正常使用状态下混凝土梁的变形情况,为今后分析碳纤维加固体外预应力连续梁提供了基础.
T1 VSAT Fade Compensation Statistical Results
Johnson, Sandra K.; Acosta, Roberto; Ugweje, Oke
2000-01-01
New satellite communication systems are steadily seeking to use higher frequency bands to accommodate the requirements for additional capacity. At these higher frequencies, propagation impairments that did not significantly affect the signal at lower frequencies begin to have considerable impact. In Ka-band. the next logical commercial frequency band to be used for satellite communication, attenuation of the signal due to rain is a primary concern. An experimental satellite built by NASA, the Advanced Communication Technology Satellite (ACTS). launched in September 1993, is the first U.S. communication satellite operating in the Ka-band. In addition to higher carrier frequencies, a number of other new technologies, including on-board baseband processing. multiple beam antennas, and rain fade detection and compensation techniques, were designed into the ACTS. Verification experiments have been conducted since the launch to characterize the new technologies. The focus of this paper is to characterize the method used by the ACTS TI Very Small Aperture Terminal (TI VSAT) ground stations in detecting the presence of fade in the communication signal and to adaptively compensate for it by the addition of burst rate reduction and forward error correction. Measured data obtained from the ACTS program was used to validate the compensation technique. A software process was developed and demonstrated to statistically characterize the increased availability achieved by the compensation techniques in terms of the bit error rate time enhancement factor. Several improvements to the ACTS technique are discussed and possible implementations for future Ka band system are offered.
DAFNE Lifetime Optimization with Octupoles and Compensating Wires
Milardi, C; Preger, M A; Raimondi, P; Zobov, M; Shatilov, D
2008-01-01
Long-range beam-beam interactions (parasitic crossings) were one of the main luminosity performance limitations for the lepton F-factory DAFNE in its original configuration. In particular, the parasitic crossings led to a substantial lifetime reduction of both beams in collision. This puts a limit on the maximum storable current and, as a consequence, on the achievable peak and integrated luminosity. In order to mitigate the problem, numerical and experimental studies of the parasitic crossings compensation by current-carrying wires have been done. During the operation for the KLOE experiment two such wires have been installed at both ends of the interaction region. They produced a relevant improvement in the lifetime of the weak beam (positrons) at the maximum current of the strong one (electrons) without luminosity loss, in agreement with the numerical predictions. The same compensating mechanism has been adopted during the run for the FINUDA experiment as well, with less evident benefits than in the previo...
Coase Competition and Compensation
Hal Varian
1994-01-01
I show that the Pigovian solution to a simple externalities problem and a particular Coasian solution can be viewed as competitive equilibria from different initial endowments. I also describe the ``compensation mechanism,'' a mechanism that implements either the Coasian or Pigovian solution as the outcome of an economically natural bargaining game.
Ivanov, S V
1981-01-01
Collective effects in the acceleration and storage of particles have recently attracted considerable interest. The authors discuss the theory of the longitudinal multipole instabilities of coupled modes of a bunched beam. Up to now, there has been no electrodynamic calculation of the excitation of the resonant elements around the beam, so that only impedances of a simple resonator type are used (the variations in the longitudinal component of the electric field on the resonator axis are not taken into account). Furthermore, and particularly significantly, elements of a waveguide nature have been ignored (the accelerating systems of the CERN SPS synchrotron in the working frequency band are examples of such elements). The authors' intention is to correct these deficiencies of the theory. (7 refs).
STABILITY OF FGM BEAM UNDER ACTION OF NON-CONSERVATIVE FORCE AND THERMAL LOADS%非保守力和热载荷作用下FGM梁的稳定性
Institute of Scientific and Technical Information of China (English)
赵凤群; 王忠民
2012-01-01
The stability of a FGM beam under the action of thermal loads and a uniformly distributed tangential follower force is analyzed.The material properties(Young’s modulus and mass density) of the beam are assumed to be varied continuously through the height direction according to a simple power-law distribution in terms of volume fraction of material constituents,and to be temperature-dependent.The temperature distribution of FGMs is assumed to be varied through the height direction following a one-dimensional steady-state heat conduction equation.The variation of Young’s modulus along the thickness of the beam for different values of graded index and temperature are calculated.The governing differential equations built on Euler-Bernoulli beam theory for the FGM beam are solved by using a WDQ method.The effect of the graded index,temperature,and follower force on vibration behaviors and stability of a simple supported non-conservative FGM beam are discussed.%研究了在热载荷和切向均布随从力作用下FGM梁的稳定性问题。假设材料常数（即弹性模量和密度）随温度及沿截面高度连续变化,且材料常数按各材料的体积分数以幂率变化,温度分布满足一维热传导方程,计算了不同梯度指标和不同温度下FGM梁的弹性模量随截面高度变化情况。基于Euler-Bernoulli梁理论,建立梁的控制微分方程,用小波微分求积法（WDQ法）求解,分析了梯度指标、温度、随从力等参数对简支FGM梁振动特性与稳定性的影响。
Behavior of Composite Columns Subjected to Lateral Cyclic Loading
AL-Bdoor, Mazen
2013-01-01
ABSTRACT: Nonlinear 3-D finite element models were developed to investigate the cumulative damage of composite columns subjected to cyclic loading by comparing the effects of different levels of axial loads on the cyclic capacity of steel, reinforced concrete, and composite beam-columns. The beam-column specimens were modeled as fixed cantilever beam-columns with an axial load level of 10%, 15%, and 20% of their axial load capacity as well as cyclic loading similar to that suggested ...
Energy Technology Data Exchange (ETDEWEB)
Reiche, H. M. [LANSCE Lujan Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); New Mexico State University, Las Cruces, New Mexico 88003 (United States); Vogel, S. C.; Larson, E. J. [LANSCE Lujan Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Mosbrucker, P. [LANSCE Lujan Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Mechanical and Materials Engineering, Queen' s University, Kingston K7L 3N6 (Canada); Daymond, M. R. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston K7L 3N6 (Canada)
2012-05-15
A resistive furnace combined with a load frame was built that allows for in situ neutron diffraction studies of high temperature deformation, in particular, creep. A maximum force of 2700 N can be applied at temperatures up to 1000 deg. C. A load control mode permits studies of, e.g., creep or phase transformations under applied uni-axial stress. In position control, a range of high temperature deformation experiments can be achieved. The examined specimen can be rotated up to 80 deg. around the vertical compression axis allowing texture measurements in the neutron time-of-flight diffractometer HIPPO (High Pressure - Preferred Orientation). We present results from the successful commissioning, deforming a Zr-2.5 wt.% Nb cylinder at 975 deg. C. The device is now available for the user program of the HIPPO diffractometer at the LANSCE (Los Alamos Neutron Science Center) user facility.
Institute of Scientific and Technical Information of China (English)
贺国栋; 阮欣; 石雪飞; 徐亮
2014-01-01
为了分析钢锚梁索塔锚固区混凝土塔壁的水平受力性能，首先必须明确索力作用下混凝土塔壁和钢锚梁分别具体承担了多少水平力。为此，研究了各种构造形式下钢锚梁锚固体系的水平荷载传递途径，表明锚固区的水平荷载分配与结构的构造形式和施工过程有关。利用变形协调原理，推导了固定连接方式的锚固体系在斜拉索水平分力下钢锚梁与混凝土塔壁的荷载分配计算公式。研究了各种构造形式下钢锚梁锚固体系的水平荷载分配具体计算方法。通过有限元计算对简化计算公式进行验证，误差约为6．5％，表明简化公式具有较好的准确性。%In order to analyze the mechanical behavior of concrete tower wall in the steel anchor beam anchor-age zone of a bridge pylon,it is interested to understand the distribution proportion between the concrete tower wall and the steel anchor beam under cable force.This paper studied the load transfer pathways and distribu-tion relationship for the steel anchor beam anchorage system under various structural forms.It was found that that the load distribution was associated with structural forms and construction processes.By using the deform-ation compatibility principle,the load distribution formula of fixed connection anchorage system under the hori-zontal component of cable force was derived.The results calculated by using this simplified formula were com-pared with the finite element result,which indicates the validity of the formula with a error of about 6.5%.
Institute of Scientific and Technical Information of China (English)
宋玉普; 韩基刚
2012-01-01
为了研究在疲劳荷载作用下,梁内钢筋的应力变化情况,通过12片后张有粘结部分预应力混凝土梁的疲劳试验,研究了与疲劳破坏密切相关的钢筋最大应力、应力幅的变化规律.结果表明：在梁的使用阶段,预应力钢筋与非预应力钢筋的应力幅比值处于等比例变化,非预应力钢筋应力幅是影响部分预应力混凝土梁疲劳性能的关键因素.随着重复荷载次数的增加,钢筋与混凝土之间粘结性能的退化和有效预应力的不断降低是两种不同类型钢筋破坏并不同步的两个重要原因.最后,在试验分析的基础上,提出了开裂截面处消压后预应力钢筋应力增量的计算公式,计算结果与试验结果吻合较好.%To investigate the stress variation of reinforcement in beam under fatigue loads,in this paper,based on fatigue test results of 12 post-tensioned partially prestressed concrete beams,the changes of reinforced maximum,stress amplitude which are closely related with the fatigue failure of partially prestressed concrete beams are obtained.The experimental results suggest that the prestressed and non-prestressed reinforced are basically at the same ratio of development.It has been found that the key factors of affecting fatigue capability of partially prestressed concrete beams are stress amplitude of reinforcement.The bond degradation of reinforcement and reduction of effective prestressed stress lead to stress redistribution,which are the two main important reasons why prestressed and non-prestressed reinforced damages are not in desynchronized way with the increase of repeated loading.Finally,a calculation method of prestressed steel stress increment in a cracked section after decompression is proposed by the experimental analysis,and the calculation results are matched with the test results quite well.
Institute of Scientific and Technical Information of China (English)
李建慧; 李爱群; 李喜平; 袁辉辉
2009-01-01
Jiangxinzhou Bridge in Nanjing is a single-pylon spatial cable self-anchored suspension bridge, whose side span main cable anchorage beam design is unique and structural loading is complex.In order to get its partial stress value and distribution as well as its force transfer path, prestressing tendons and main cable was simulated by spatial cable element, concrete anchor beam was simulated by 3D block element, and a 3D refinement finite element model was established with secondary development technology based on the platform of general finite element program.On this basis, reasonable load pattern was used to its spatial structural analysis, by which its force transfer path and stress distribution under free cable construction stage and finished stage were obtained.The results show that (1) stress value and distribution change greatly between the two stages; (2) prestressing tendons of anchor beam should be tensioned by stages according to change of main cable internal force to ensure the mechanical state of anchor beam in a reasonable range in the construction process.%南京江心洲大桥边跨主缆锚固大横梁设计独特,结构受力非常复杂.为了获得锚固横梁局部应力的大小与分布规律,对其传力途径进行研究,以通用有限元程序为计算平台,采用空间索单元模拟横梁中配置的预应力束以及主缆束股,三维块体元模拟混凝土锚固横梁,应用二次开发技术,建立精细三维有限元模型.在此基础上采用合理的加载模式对锚固横梁在空缆阶段和成桥状态2种不同工况进行应力计算与分析.结果表明:在空缆与成桥2种状态下锚目横梁的应力值与分布规律变化较大;为保证锚固横梁在施工过程中的受力状态处在合理的范围之内,锚固横梁中配置的大量预应力束应配合主缆束股的内力变化而分批次张拉.
RELIABILITY OF LENTICULAR EXPANSION COMPENSATORS
Directory of Open Access Journals (Sweden)
Gabriel BURLACU,
2011-11-01
Full Text Available Axial lenticular compensators are made to take over the longitudinal heat expansion, shock , vibration and noise, made elastic connections for piping systems. In order to have a long life for installations it is necessary that all elements, including lenticular compensators, have a good reliability. This desire can be did by technology of manufactoring and assembly of compensators, the material for lenses and by maintenance.of compensator
Firm performance and CEO compensation : Determinants of CEO compensation
Singh, Minu; Yavuz, Cigdem
2015-01-01
CEO compensation is a much discussed concept in the media and in the society in general. The center of the discussion is mostly around the high CEO compensations and the gaps between the compensation to the CEOs and to rest of the employees. As this is an interesting and topical concept, we hence wanted to examine how CEO compensation is determined in firms listed on the Oslo Stock Exchange. We wanted to examine if CEOs actually get their compensation for obtained firm performance, or if ther...
Emittance compensation of CW DC-gun photoinjector
International Nuclear Information System (INIS)
Emittance growth induced by space charge effect is very important, especially for CW DC-gun photoinjector. In this work, the linear space charge force and its effect on electron beam transverse emittance are studied, and the principle and properties of emittance compensation by solenoid are analyzed. The CAEP DC-gun photoinjector with a solenoid is also simulated by code Parmela. Simulated results indicate that the normalized transverse emittance of an 80 pC bunch at the 350 keV DC-gun ex-it is 5.14 mm · mrad. And after compensated by a solenoid, it becomes 1.27 mm · mrad. The emittance of beam is well compensated. (authors)
Compensation Consultants and CEO Pay
Kabir, Rezaul; Minhat, Marizah
2014-01-01
The study examines the practice of employing multiple compensation consultants. Examining data of a sample of UK companies over the period 2003–2006 we find that CEOs receive higher equity-based pay when firms employ more than one compensation consultant. An increase in the number of compensation co
Institute of Scientific and Technical Information of China (English)
毛德均
2015-01-01
According to the secondary load characteristics of reinforced concrete beam strengthened by bonding steel plates ,the formula for calculating relative depth of compression zone ξb is obtained by introducing the coefficient δ.Then according to the two states of the strengthened component un‐cracked and cracked w hen strengthening ,and by using the material mechanics theory and related spec‐ifications ,some formulas are obtained to calculate several important strain parameters of component section after first load ,to study the influence of component cracking or not when strengthening on ξb . The results show that considering the secondary load influence ,ξb should be synthetically determined by the field holding load condition ,the cracking condition of the strengthened component and the steel plate type ,accordingly the maximum amount of steel plate can be reasonably determined ,and conse‐quently the failure of over‐reinforced beam can be avoided .%文章根据粘贴钢板加固钢筋砼梁的二次受力特点，引入系数δ，提出了构件加固后相对界限受压区高度ξb 计算公式。根据被加固构件加固时未开裂和已开裂2种状态，运用材料力学理论及相关规范得出了一次受力后构件截面几个重要应变参数的计算公式，从而研究了加固时构件开裂与否对ξb 的影响。研究结果表明：考虑二次受力影响，应根据被加固构件的现场持荷、开裂状况以及钢板类型来综合确定ξb，从而合理确定最大粘钢量，避免加固后梁出现超筋破坏。
Compensability index for compensation radiotherapy after treatment interruptions
Directory of Open Access Journals (Sweden)
Putora Paul
2012-12-01
Full Text Available Abstract Background The goal of our work was to develop a simple method to evaluate a compensation treatment after unplanned treatment interruptions with respect to their tumour- and normal tissue effect. Methods We developed a software tool in java programming language based on existing recommendations to compensate for treatment interruptions. In order to express and visualize the deviations from the originally planned tumour and normal tissue effects we defined the compensability index. Results The compensability index represents an evaluation of the suitability of compensatory radiotherapy in a single number based on the number of days used for compensation and the preference of preserving the originally planned tumour effect or not exceeding the originally planned normal tissue effect. An automated tool provides a method for quick evaluation of compensation treatments. Conclusions The compensability index calculation may serve as a decision support system based on existing and established recommendations.
Institute of Scientific and Technical Information of China (English)
慕莉; 刘玉田
2012-01-01
钢铁企业配电网中大量的非线性和冲击性负荷严重影响企业电网的电能质量及相关设备的使用寿命.充分考虑了冲击性负荷的特点,在带时变噪声统计估值器的Sage-Husa自适应滤波算的基础上,提出了一种改进Sage-Husa自适应滤波超短期预测算法.改进后的算法可以正确估计系统的输入噪声方差Q和测量噪声方差R,提高了预测准确度,同时继承了原算法的优点,计算速度快,存储量小,适合于在线应用.某钢铁企业轧钢车间部分供电母线的实际预测结果表明:该算法预测精度较高,计算速度快,可用于指导无功动态补偿,提高电压合格率和电气节能效果.%The impact loads with no definite period in iron and steel enterprise seriously affect the power quality in the company power supply system and the working life of relevant equipment. Considering the special characteristics of impact loads and based on Sage-Husa adaptive filtering algorithm with estimator of time-variant variation noise, an improved Sage-Husa adaptive filtering algorithm is proposed in this paper. This new algorithm can estimate the system input noise variance and output noise variance correctly, and effectively improve forecasting accuracy. Meanwhile, the improved algorithm inherits the advantages of the original algorithm, with rapid computing speed and high storage capacity small. The new algorithm is perfectly suitable for online applications. The reactive power forecasting results of some substation buses in an iron and steel enterprise show that the high accuracy and rapid computing rate of the algorithm.
Braun, R. M.; Cheng, J.; Parsonage, E. E.; Moeller, J.; Winograd, N.
2006-07-01
The surface of a triblock copolymer, containing a solid-phase drug, was investigated using 15 keV Ga + and 20 keV C 60+ ion beams. Overall, the results illustrate the successful use of a cluster ion beam for greatly enhancing the molecular ion and high-mass fragment ion intensities from the surface and bulk of the polymer system. The use of C 60+ also established the ability to see through common overlayers like poly(dimethyl siloxane) which was not possible using atomic ion sources. Moreover, the use of C 60+ allowed depth profiles to be obtained using primary ion dose densities in excess of 6 × 10 14 C 60+/cm 2. Resulting sputter craters possess relatively flat bottoms without the need for sample rotation and reached depths of ca. 2 μm. AFM results illustrate the more gentile removal of surface species using cluster ions. Specifically, phase contrast and topographic images suggest the relatively high ion doses do not significantly alter the phase distribution or surface topography of the polymer. However, a slight increase in rms roughness was noticed.
Energy Technology Data Exchange (ETDEWEB)
Braun, R.M. [Surface Science Laboratory, Bausch and Lomb Inc., Rochester, NY 14609 (United States)]. E-mail: rbraun@bausch.com; Cheng, J. [Department of Chemistry, Penn State University, University Park, PA 16802 (United States); Parsonage, E.E. [Boston Scientific Inc., Maple Grove, MN 55311-1566 (United States); Moeller, J. [Boston Scientific Inc., Maple Grove, MN 55311-1566 (United States); Winograd, N. [Department of Chemistry, Penn State University, University Park, PA 16802 (United States)
2006-07-30
The surface of a triblock copolymer, containing a solid-phase drug, was investigated using 15 keV Ga{sup +} and 20 keV C{sub 60} {sup +} ion beams. Overall, the results illustrate the successful use of a cluster ion beam for greatly enhancing the molecular ion and high-mass fragment ion intensities from the surface and bulk of the polymer system. The use of C{sub 60} {sup +} also established the ability to see through common overlayers like poly(dimethyl siloxane) which was not possible using atomic ion sources. Moreover, the use of C{sub 60} {sup +} allowed depth profiles to be obtained using primary ion dose densities in excess of 6 x 10{sup 14} C{sub 60} {sup +}/cm{sup 2}. Resulting sputter craters possess relatively flat bottoms without the need for sample rotation and reached depths of ca. 2 {mu}m. AFM results illustrate the more gentile removal of surface species using cluster ions. Specifically, phase contrast and topographic images suggest the relatively high ion doses do not significantly alter the phase distribution or surface topography of the polymer. However, a slight increase in rms roughness was noticed.
Institute of Scientific and Technical Information of China (English)
杜宏保; 陶荣
2015-01-01
研究线性荷载下混凝土梁抗拉强度幂值函数预测模型，对筋混凝土柱的拟静力试验进行模拟分布，构建钢筋混凝土柱状结构下的应力损伤模型，实现对混凝土梁抗拉强度幂值函数预测，对提高建筑物的强度具有重要意义。进行混凝土抗拉强度线性徐变的本构关系分析，综合考虑混凝土的材料非线性效应与时间非线性效应，根据低短期荷载模型设计混凝土结构的非线性徐变多块结构化网格，得到线性荷载下的混凝土梁多块结构化网格模型。试验采用4点弯曲分级加载方式，分别是试件DSHCW-1、试件DSHCW-2、试件DSHCW-3和试件DSHCW-4，进行幂值函数预测。得到不同等级地震作用下的剩余抗拉强度与承载力数值分析，构建混凝土的抗拉强度滞回曲线，实验结果得出，采用该试件模型，能有效提高混凝土梁的抗拉强度，通过对幂值函数准确预测，对混凝土梁结构的强度提高有较大贡献，为高层建筑抗震设计计算或加固提供数学模型和理论基础。%The strength of concrete beams under tensile load power linear value function prediction model is studied, to sim⁃ulate the distribution of the pseudo static tests of reinforced concrete column, construction stress damage model of structure of reinforced concrete columns under the realization of value function, to forecast the power beam concrete tensile strength, to improve the strength of the building is of great significance. Analysis of the constitutive relation of the linear creep of con⁃crete tensile strength, considering the material nonlinear effect and time nonlinear effect of concrete, according to the low short-term load model of nonlinear creep of concrete structure design of multi block structured grid, get the concrete beam multi block structured grid model under linear load. Experiments using 4 point bending multi-stage loading, respectively is DSHCW-1
International Nuclear Information System (INIS)
The mechanism of a ferrite-loaded rf cavity is explained from the point of view of its operation. Then, an analysis of the automatic cavity-tuning system is presented using the transfer function; and a systematic analysis of a beam-feedback system using transfer functions is also presented. (author)
预应力混凝土空心板梁静力荷载试验分析%Static Load Experiment Analysis of Prestressed Concrete Hollow Plate Beam
Institute of Scientific and Technical Information of China (English)
徐凯燕; 刘灿
2012-01-01
Take a 20 m hollow plate beam as an example, the static load experiment was conducted, and the experimental data about overall displacement, cross-section strain and the crack were analyzed carefully. The re-sults show that;l) its stiffness satisfied the design code. 2) the actual measured strain take on linear variety along the section height, which match the plane cross-section assumption; and the stress experiment coefficient is 0. 562, which satisfied the testing specification. 3 ) there is no crack occur under the last experiment load case. Which show that the hollow plate beam satisfies the design code.%进行了跨径为20m的预应力混凝土空心板静力载荷试验,对梁的整体挠度、梁截面应变以及抗裂性试验数据进行了详细分析.结果表明:(1)该梁的刚度满足设计要求；(2)实测应变沿截面高度呈线形变化,符合平截面假定；应力校验系数为0.562,满足试验规范的要求；(3)在最大级试验荷载作用下,未发现有横向裂缝产生,试验空心板梁满足设计要求.
Institute of Scientific and Technical Information of China (English)
魏湛力; 褚少辉; 张涛; 张艳玲
2016-01-01
With the rapid development of China's transport business and increasing load of highway and bridge, coupled with the geographic conditions of many mountains and rivers in China, bridge design and construction is attracting more and more attention. In new bridge design, bridge construction monitoring and finished bridge test, the calculation of stress, strain and deflection is extremely important. This paper uses finite element analysis software ANSYS for static analysis of continuous variable cross-section beam bridge model, mainly to comprehensively evaluate the stress level of tapered beam through analysis and comparison of deformation figure and stress diagram under different loading, in order to provide reference for further study of other characteristic of the continuous variable cross-section bridge and structural optimization.%随着我国交通事业的高速发展，公路桥梁负荷的日益加重，再加上我国多河流山川的地理条件，桥梁设计和施工越来越受到重视。在新桥设计、桥梁施工监控和成桥试验检测中，应力、应变，挠度计算都极其重要。利用有限元分析软件ANSYS对连续变截面梁桥模型进行静力分析，主要是通过分析对比不同载荷作用下的变形图、应力图，全面评价变截面梁的应力水平，为进一步研究连续变截面梁桥的其它特性和结构优化提供参考。
Institute of Scientific and Technical Information of China (English)
欧阳煜; 张雅男
2012-01-01
Based on the mathematical model for dynamics of a saturated poroelastic Timoshenko beam, the dynamical behavior of a simply-supported saturated poroelastic Timoshenko beam, with two permeable ends and subjected to a sudden step load at its midpoint, is investigated. The analytical solution is obtained, and the variations of the dimensionless deflections, bending moments of the solid skeleton of the poroelastic beam, and equivalent couples of the pore fluid pressure against the dimensionless time are given. The effects of the shearing and rotation inertia of the cross section on the dynamical behavior are examined, and the dynamical behaviors of the saturated poroelastic Timoshenko, Shear, Rayleigh and Euler-Bernoulli beams are compared. It is shown that the shearifig effect increases the amplitudes and periods of the dynamical responses of the saturated poroelastic Timoshenko beam, while the rotation inertia effect of the cross section only increases the periods. The interaction between the solid skeleton and pore fluid plays a role as viscidity. With the interaction coefficient increasing, the deflections and bending moments of the saturated poroelastic beam decrease, and the amplitudes of the equivalent couple of the pore fluid pressure increase, furthermore, the attenuation of the vibration amplitudes is more rapidly with the increasing of the interaction coefficient. Meanwhile, with the slenderness ratio increasing, the amplitude and period of the saturated poroelastic Timoshenko beam decrease gradually, and they converge to those of the saturated poroelastic Euler-Bernoulli beam.%基于饱和多孔弹性Timoshenko梁的动力数学模型，研究了梁中点承受突加载荷作用两端可渗透饱和多孔弹性Timoshenko简支梁的动力响应，得到了问题的解析解，给出了梁中点无量纲挠度、固相骨架弯矩和孔隙流体压力等效力偶等随无量纲时间的响应。考察了剪切和横截面转动惯性效应等对动力响应
The electrostatic fields of a tilted beam
International Nuclear Information System (INIS)
Calculations are presented of the electrostatic fields resulting from the tilted charge distribution in beams inclined to the vacuum chamber axis in storage rings or dispersive beam lines. Expressions are also given for a beam displaced from the axis. Comparisons made with untilted field amplitudes indicate that the longitudinal space-charge fields of an untilted beam can be compensated by an RF system or ramped induction system of some sort while the longitudinal fields of a tilted beam, since they tend to produce longitudinal shear in the centre of the beam, would be much harder to compensate. Longitudinal bunch-shape distortions may thus be expected to develop in a tilted beam. In addition, the transverse fields, since they tend to shift the centre of the transverse motion, may lead to transverse bunch-shape distortions. (U.K.)
Analysis and Design of Backing Beam for Multipole Wiggler (MPW14) at PLS
Lee, Hong-Gi; Jung, Young-Gyu; Park, Ki-Hyeon; Sik Han, Hong; Suck Suh, Hyung; Wha Chung, Chin; Woo Lee, Wol
2005-01-01
Pohang Accelerator Laboratory (PAL) had developed and installed a Multipole Wiggler (MPW14) to utilize high energy synchrotron radiation at Pohang Light Source (PLS). The MPW14 is a hybrid type device with period of 14 cm, minimum gap of 14 mm, maximum flux density of 2.02 Tesla and total magnetic structure length of 2056 mm. The support locations and structure of an insertion device are optimized to achieve a minimum deflection due to the magnetic loads. A Finite Element Analysis (FEA) is performed to find out the amount of maximum deflection and optimal support positions on the backing beam, the support and drive structures of the MPW14 under expected magnetic load of 14 tons. To reduce the deflection effect further, two springs are designed and installed to compensate the gap dependent magnetic loads. The optimized deflection is estimated to be about 20.6 ? while the deflection before optimization is 238 ?.
SMALL ANGLE CRAB COMPENSATION FOR LHC IR UPGRADE
Energy Technology Data Exchange (ETDEWEB)
CALAGA,R.; DORDA, U.; OHMI, D.; OIDE, K.; TOMAS, R.; ZIMMERMANN, F.
2007-06-25
A small angle (< 1 mrad) crab scheme is an attractive option for the LHC luminosity upgrade to recover the geometric luminosity loss from the finite crossing angle [I]. The luminosity loss increases steeply to unacceptable levels as the IP beta function is reduced below its nominal value (see Fig. 1 in Ref. [2]). The crab compensation in the LHC can be accomplished using only two sets of deflecting RF cavities, placed in collision-free straight sections of the LHC to nullify the effective crossing angles at IPI & IP5. We also explore a 400 MHz superconducting cavity design and discuss the pertinent RF challenges. We present IR optics configurations with low-angle crab crossing, study the beam-beam performance and proton-beam emittance growth in the presence of crab compensation, lattice errors, and crab RF noise sources.
Magnetic field measurement and compensation in the Recycler Electron Cooler
Energy Technology Data Exchange (ETDEWEB)
Tupikov, V.; /Fermilab; Kazakevich, Grigory M.; /Novosibirsk, IYF; Kroc, T.K.; Nagaitsev, S.; Prost, L.; Shemyakin, A.; Schmidt, C.W.; Sutherland, M.; Warner, A.; /Fermilab
2005-09-01
Cooling of 8.9-GeV/c antiprotons in the Recycler Electron Cooler requires a round 4.34-MeV electron beam with a small angular spread propagating through a 20-m long cooling section. To confine the electron beam tightly and to keep its total transverse angles below 0.2 mrad the cooling section is immersed in a solenoidal field of 50-200 G. The field was measured with a compass-based sensor (transversal) and a hall-probe (longitudinal) after installation of the solenoids into the Recycler tunnel. For the field strength of 105 G, the transverse field components were compensated to the level that provided corresponding dipole beam oscillations below 0.1 mrad, which in turn allowed the first cooling of antiprotons in the GeV energy range. This paper discusses the field measurements and compensation scheme including the results of dipole oscillation measurements.
2010-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Compensation. 3.4 Section..., Compensation, and Dependency and Indemnity Compensation General § 3.4 Compensation. (a) Compensation. This term...) Disability compensation. (1) Basic entitlement for a veteran exists if the veteran is disabled as the...
International Nuclear Information System (INIS)
The tip deflections of wind turbine blades should be monitored continuously to prevent catastrophic failures of wind turbine power plants caused by blades hitting the tower. In this paper, a calculation method for wind turbine blade tip deflection is proposed using a finite difference method based on arbitrary beam bending and moment theory using measured strains. The blade strains were measured using fiber optic Bragg grating sensors. In order to confirm this method, a 100 kW composite wind turbine blade was manufactured with epoxy molded fiber optic Bragg grating (FBG) sensors installed in the shear web of the blade. A number of these sensors, normal FBG probes, were fabricated to only measure strains and the other sensors, temperature compensated FBG probes, were prepared to also measure strain and temperature. Because the output signals of FBG sensors are dependent on strains as well as temperatures, the sensor output signals should be compensated by the temperatures to obtain accurate strains. These FBG sensors were attached on the lower and upper parts of the web at one meter intervals throughout the entire length of the blade. To evaluate the measurement accuracy of the FBG sensors, conventional electrical strain gauges were also bonded onto the surface of the web beside each FBG sensor. By performing a static load test of the blade, the calculated tip deflection of the blade was well determined within an average error of 2.25%. (paper)
International Nuclear Information System (INIS)
Some industrial loads with high power consumption levels, deteriorate the power quality in electrical networks, due to their nonlinearity, low power factor and phase unbalance. These loads can cause distortions and undesirable fluctuations in the network voltage or current waveforms. One of the most practical ways to alleviate the destructive impact of such loads is application of parallel reactive power compensators. In this paper, a novel control method is introduced for reactive power compensator using a TCR static VAR compensator. The control system is used for power factor correction and load balancing in a three-phase system. In the proposed method, the active and reactive power components are measured in each phase. These components are used to calculate the susceptances in each compensator phase, so that proper load compensation is fulfilled. In these calculations, deviations of load voltages from the nominal values are also considered. Computer simulations are carried out in order to verify the effectiveness of the introduced control method. These simulations demonstrate the efficiency of the control method in power factor correction and load balancing. Moreover, comparisons are made between the proposed method and other implemented compensation methods, and the better performance of the proposed method is demonstrated
Directory of Open Access Journals (Sweden)
J. Mar
2013-01-01
Full Text Available The shipborne phased array radar must be able to compensate the ship’s motion and track the maneuvering targets automatically. In this paper, the real-time beam pointing error compensation mechanism of a planar array antenna for ship’s motion is designed to combine with the Kalman filtering. The effect of beam pointing error on the tracking performance of shipborne phased array radar is examined. A compensation mechanism, which can automatically correct the beam pointing error of the planar antenna array, is proposed for shipborne phased array radar in order to achieve the required tracking accuracy over the long dwell time. The automatic beam pointing error compensation mechanism employs the parallel fuzzy basis function network (FBFN architecture to estimate the beam pointing error caused by roll and pitch of the ship. In the simulation, the models of roll and pitch are used to evaluate the performance of beam pointing error estimation mechanism based on the proposed parallel FBFN architecture. In addition, the effect of automatic beam pointing error compensation mechanism on the tracking performance of adaptive extended Kalman filter (AEKF implemented in ship borne phased array radar is also investigated. Simulations find out that the proposed algorithms are stable and accurate.
Analysis of emittance compensation and simulation results to photo-cathode RF gun
LiuShengGuang
2002-01-01
The emittance compensation technology will be used on the photo-cathode RF gun for Shanghai SDUV-FEL. The space charge force and its effect on electron beam transverse emittance in RF gun is studied, the principle of emittance compensation in phase-space is discussed. The authors have designed a compensation solenoid and calculated its magnetic field distribution. Its performance has been studied by the code PARMELA. A simulation result indicates that the normalized transverse RMS emittance for electron beam of 1.5 nC is 1.612 pi mm centre dot mrad, electron energy E = 5.71 MeV
DEFF Research Database (Denmark)
Chen, Zhe; Pedersen, John Kim; Blaabjerg, Frede
2004-01-01
A hybrid compensation system consisting of an active filter and a group of distributed passive filters has been studied previously. The passive filters are used for each distorting load or Dispersed Generation (DG) unit to remove major harmonics and provide reactive power compensation. The active...
The Interplay between Director Compensation and CEO Compensation
Dan Lin; Lu Lin
2014-01-01
This paper empirically examines the determinants of director compensation and CEO compensation and investigates whether director compensation has an effect on CEO compensation. Based on 713 firms (or 2,852 firm-years) between 2007 and 2010, we find that CEO tenure is related to the ability of the CEO in influencing the boardâ€™s pay determination process. However, sitting on the board does not strengthen the CEOâ€™s power over the board during the pay negotiation process. More importantly, we...
Large deformation dynamic bending of composite beams
Derian, Edward J.
1985-01-01
The large deformation response of composite beams subjected to a dynamic axial load was studied. The beams were loaded with a moderate amount of eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied in order to determine the difference between the static and dynamic failure. Twelve different la...
Institute of Scientific and Technical Information of China (English)
Wang Yi; He Lenian; Ning Zhihua; Shao Yali
2009-01-01
unit-gain compensation ceil and pseudo-ESR (equivalent serial resistor of load capacitor) power stage have been realized by this controllable resistor.Their advantages and limitations are discussed and verified by simulation results.
Compensation for Power Quality Improvement in Electric Arc Furnace with Considering Economic Index
Directory of Open Access Journals (Sweden)
Ghazanfar Shahgholian
2012-03-01
Full Text Available In recent years, on the one hand with increasing application of nonlinear loads in power systems and no sinusoidal currents that extracted from system, and on the other hand increasing loads sensitive to power quality and destructive effects of nonlinear loads on power quality of power systems, compensation these loads has been converted to one of the main issues in power systems. The use of flexible AC transmission system (FACTS devices is one of the most progressive methods which are used for improving power quality. In this paper, series and parallel compensators of static synchronous compensator (STATCOM and dynamic voltage restorer (DVR are introduced and the comparison of these two in compensating of power quality phenomena from electric arc furnace is provided. STATCOM is a shunt active filter and DVR is a series active filter. Method which has been selected for control of every one of these devices is an optimal control way that it minimizes power losses.
Calculation of compensation for reactive power in electrical networks of mining enterprises
Energy Technology Data Exchange (ETDEWEB)
Rogal' skiy, B.S.; Golota, A.D.
1984-01-01
A calculation is made of the compensation for reactive energy because of connection of the BK capacitors directly at the load. The calculation is simple and fairly accurate. The calculation algorithm is easily realized on a computer.
Feedback Control of Transmission Line by Static VAR Compensators (TSC & TCR Using Fuzzy Logic
Directory of Open Access Journals (Sweden)
Arushi Jaiswal
2013-07-01
Full Text Available Voltage profile maintenance of a transmission system can be done by using feedback control methodology and the compensation technique used is Static VAR compensation. This thesis describes a MATLAB based SIMULINK model that can be implemented in real time systems to maintain a constant voltage profile during load changes and fault conditions. In any power system the basic requirement is to keep the voltage of the system constant so that the load functions properly. Whenever there is a fault or any load is disconnected, the active and reactive power requirements of the system changes. As a result, the voltage of the system changes. Therefore to maintain a constant voltage profile shunt compensators are used near the load end, in the model presented in this project. Fuzzy logic is also implemented to set the proper compensation required
Institute of Scientific and Technical Information of China (English)
陈兰; 张新洲; 孙字; 杨树田; 常欣
2011-01-01
针对大型卷板机上辊挠曲变形的补偿难题,利用ANSYS有限元优化方法,对某21 m大型船用卷板机的上辊支承辊的数量、位置及施加载荷的分布进行了合理优化,进而提出了挠度补偿措施.结合有限元分析方法分别得到了上辊和上梁在优化载荷作用下和整体模型在工作载荷作用下的挠曲变形,并对预补偿后的情况进行了分析,补偿后上辊的最大挠度是0.71 mm,几乎能使上辊趋于水平,结果满足卷板机上辊挠曲变形的补偿要求.%In order to solve the problem of deflection compensation of upper roller for large marine bending machine, using FEA optimization method based on ANSYS, the amount, locations and the imposed loads of bearing rollers of 21 m large marine bending machine were optimized reasonably and the deflection compensation measure was proposed. The deflection of the upper roller and beam in optimizing loads and overall role model in the working load were obtained through finite element analysis method. After compensation, the maximum deflection is 0. 71 mm, the upper roller almost tends to be level. The result of pre-compensation by finite element analysis method shows that it is feasible for deflection compensation of upper roller for large marine bending machine.
Institute of Scientific and Technical Information of China (English)
武志杰; 陈悦
2013-01-01
利用ANSYS建立14根碳纤维布加固钢筋混凝土简支梁模型，分析在两种配筋率情况下，不同初始荷载对钢筋混凝土梁碳纤维布抗弯加固效果的影响。结果表明：碳纤维布加固可显著提高梁的屈服荷载和极限荷载，梁的屈服荷载和极限荷载的提高幅度随着初始荷载的增加而减小；配筋率越小，受拉钢筋利用越充分，梁的极限荷载提高幅度越明显。%Fourteen reinforced concrete simply supported beam models with CFRP sheets were built by using ANSYS, and the influence of different initial loads on the reinforcement and flexural strength effects of CFRP sheets in two steel rein-forcement ratios was analyzed. The results indicated that reinforced carbon fiber sheet could significantly increase the yield-ing load and ultimate load of the beam. The enhancement of yielding load and ultimate load decreased with the increase of initial load. The more adequate the steel reinforcement utilization rate was, the more significantly the ultimate load with small reinforcement ratio would be improved.
Directory of Open Access Journals (Sweden)
Sevillano, E.
2016-06-01
Full Text Available The development of monitoring technologies particularly suitable to be used with novel CFRP strengthening techniques has gained great attention in recent years. However, in spite of the high performance of these advanced composite materials in the strengthening and repairing of structures in service, they are usually associated with brittle and sudden failure mainly caused by debonding phenomena, originated either at the CFRP-plate end or at the intermediate areas in the vicinity of flexural cracks in the RC beam. Thus, it is highly recommended for these structures to be monitored in order to ensure their integrity while in service. Specifically, the feasibility of smart sensing technologies such as Fiber Bragg Grating (FBG sensors and piezo-impedance transducers (PZT has been studied. To the knowledge of the authors, none serious study has been carried out until now concerned to the topic of damage detection due to debonding in rehabilitated structures with CFRP composites.El desarrollo de tecnologías de monitorización aplicables junto con las novedosas técnicas de refuerzo basadas en materiales CFRP ha recibido una atención creciente los últimos años. Sin embargo, a pesar del alto rendimiento de estos avanzados materiales compuestos en la reparación y refuerzo de estructuras en servicio, están habitualmente asociados a fallos frágiles y repentinos causados principalmente por fenómenos de despegue, originados bien en los extremos del refuerzo, bien en áreas intermedias en las proximidades de grietas de flexión existentes en la viga. Por tanto, es altamente recomendable monitorizar estas soluciones estructurales de cara a garantizar su integridad en servicio. Específicamente, se ha estudiado la viabilidad de sensores inteligentes tales como los sensores Fiber Bragg Grating (FBG o los transductores piezoeléctricos (PZT. Hasta donde los autores saben, no se han realizado estudios serios hasta la fecha abordando la detección de da
Adaptive rain fade compensation
Rautio, J. C.
1980-01-01
A large available margin must be provided for satellite communications systems operating near 20 GHz, which occasionally experience fades due to rain attenuation. It is proposed that this margin may be achieved in high-capacity FDMA satellites by dynamically providing a large margin to those links which are experiencing deep fades, while maintaining a small fade margin on all others. Single-beam SCPC operation and multiple-beam, satellite-switched FDMA systems are described, and the optimization of the dynamic FDMA links in a severely fading environment is investigated. A solution is derived which takes into account: (1) transponder intermodulation distortion, (2) cochannel and cross-polarization antenna interference, and (3) rain fade characteristics. The sample system configuration presented shows that such systems reach availability levels approaching 0.9999 at Ka-Band.
International Nuclear Information System (INIS)
The philosophy of these tests is to measure the motion of a low current, small diameter electron beam in the accelerator before running high current. By using low current, we can study particle motion in the applied fields without any extra complications associated with the self-forces of high currents. With the steering magnets off, we have measured the transverse drift of the probe beam. Also, we have used the probe beam to optimize the current in the steering magnets to compensate for the drift. There have been concurrent efforts to locate the source of the error field which is presumed to cause the drift. So far, the source has not been established but the search is continuing
Modeling and control of thermostatically controlled loads
Kundu, Soumya; Sinitsyn, Nikolai; Backhaus, Scott; Hiskens, Ian
2011-01-01
As the penetration of intermittent energy sources grows substantially, loads will be required to play an increasingly important role in compensating the fast time-scale fluctuations in generated power. Recent numerical modeling of thermostatically controlled loads (TCLs) has demonstrated that such load following is feasible, but analytical models that satisfactorily quantify the aggregate power consumption of a group of TCLs are desired to enable controller design. We develop such a model for...
Mechanically reinforced glass beams
DEFF Research Database (Denmark)
Nielsen, Jens Henrik; Olesen, John Forbes
2007-01-01
The use of glass as a load carrying material in structural elements is rarely seen even though glass is a popular material for many architects. This is owed to the unreliable and low tensile strength, which is due to surface flaws and high brittleness of the material. These properties lead...... to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... laminated float glass beam is constructed and tested in four-point bending. The beam consist of 4 layers of glass laminated together with a slack steel band glued onto the bottom face of the beam. The glass parts of the tested beams are \\SI{1700}{mm} long and \\SI{100}{mm} high, and the total width of one...
Compensation for Power Quality Improvement in Electric Arc Furnace with Considering Economic Index
Ghazanfar Shahgholian; Maryam Golibagh
2012-01-01
In recent years, on the one hand with increasing application of nonlinear loads in power systems and no sinusoidal currents that extracted from system, and on the other hand increasing loads sensitive to power quality and destructive effects of nonlinear loads on power quality of power systems, compensation these loads has been converted to one of the main issues in power systems. The use of flexible AC transmission system (FACTS) devices is one of the most progressive methods which are used ...