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Yasuo Iijima - One of the best experts on this subject based on the ideXlab platform.
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Determining Young’s modulus of timber on the basis of a strength database and stress wave propagation velocity II: effect of the Reference Distribution database on the determination
Journal of Wood Science, 2010Co-Authors: Mariko Yamasaki, Yasutoshi Sasaki, Yasuo IijimaAbstract:A method of determining the Young’s modulus of timber using the stress wave propagation velocity without knowing the timber density was developed in our previous study. This method enables the estimation of Young’s modulus by Monte Carlo simulation using an existing database of the Young’s modulus versus density relationship as Reference. Here, in Part II, we consider the effect of the Reference Distribution database on the accuracy of the estimated Young’s modulus by the developed method. Twelve different Reference Distribution databases were used in this study, containing Young’s modulus versus density data for more than 13 000 real-size timber specimens of ten different species. We obtained the following results: (1) the Distribution of Young’s modulus estimated using an arbitrary stress wave propagation velocity depends on the Reference Distribution database employed, (2) the most important factor is not that the Reference database has data on the same species as the timber in the test, but rather that the Reference Distribution database covers the foreseeable range of timber densities within the test, and (3) the estimation accuracy is higher than about 80% when the database covers many species and has wide ranges of densities and Young’s moduli. This estimation method was developed in order to measure the Young’s modulus of timber whose density cannot be measured. Considering that the quality of lumber has a large variation, such estimation accuracy will be useful for practical applications.
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determining young s modulus of timber on the basis of a strength database and stress wave propagation velocity ii effect of the Reference Distribution database on the determination
Journal of Wood Science, 2010Co-Authors: Mariko Yamasaki, Yasutoshi Sasaki, Yasuo IijimaAbstract:A method of determining the Young’s modulus of timber using the stress wave propagation velocity without knowing the timber density was developed in our previous study. This method enables the estimation of Young’s modulus by Monte Carlo simulation using an existing database of the Young’s modulus versus density relationship as Reference. Here, in Part II, we consider the effect of the Reference Distribution database on the accuracy of the estimated Young’s modulus by the developed method. Twelve different Reference Distribution databases were used in this study, containing Young’s modulus versus density data for more than 13 000 real-size timber specimens of ten different species. We obtained the following results: (1) the Distribution of Young’s modulus estimated using an arbitrary stress wave propagation velocity depends on the Reference Distribution database employed, (2) the most important factor is not that the Reference database has data on the same species as the timber in the test, but rather that the Reference Distribution database covers the foreseeable range of timber densities within the test, and (3) the estimation accuracy is higher than about 80% when the database covers many species and has wide ranges of densities and Young’s moduli. This estimation method was developed in order to measure the Young’s modulus of timber whose density cannot be measured. Considering that the quality of lumber has a large variation, such estimation accuracy will be useful for practical applications.
Krzysztof Czuba - One of the best experts on this subject based on the ideXlab platform.
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The concept of the RF phase Reference Distribution system for SINBAD accelerator research facility
2018 22nd International Microwave and Radar Conference (MIKON), 2018Co-Authors: Maciej Urbanski, Krzysztof Czuba, Frank Ludwig, N. Ngada, U. Dorda, Heinrich Pryschelski, Holger SchlarbAbstract:SINBAD — Short Innovative Bunches and Accelerators at DESY — is the accelerator research facility, located in DESY, Hamburg, Germany. It is planned to be the place, where various experiments, related to creating ultra-short electron bunches and high gradient acceleration techniques, will take place. One of planned experiments — ARES — Accelerator Research Experiment at SINBAD — is a conventional S-band electron linac, accelerating ultra-short (single fs) electron bunches to energy of 100 MeV. To ensure proper and stable work of this accelerator, a high frequency phase Reference Distribution system needs to be designed, manufactured and tested. In this paper the concept of such system for SINBAD is presented. The design is based on authors' experience and knowledge gained during development of similar systems for FLASH, XFEL, REGAE and ESS-ERIC accelerators.
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Improved fiber-optic link for the phase Reference Distribution system for the TESLA technology based projects
Photonics Applications in Industry and Research IV, 2005Co-Authors: Krzysztof Czuba, Matthias FelberAbstract:The UV Free-Electron Laser (UVFEL) [1], The X-Ray Free-Electron Laser (XFEL) [2] and The International Linear Accelerator (ILC) [9] projects will require phase synchronization of various RF frequency subsystems on kilometer distances with accuracy better than 1ps. To fulfill these requirements, a phase Reference Distribution system concept was proposed and a prototype was developed for tests in the TESLA Test Facility 2 (TTF2). An important part of the phase Reference system is the fiber-optic phase stable, long distance link described in this paper. An interferometrical scheme with feedback on phase, suppressing long term phase drifts induced by temperature changes was developed and tested in laboratory and under accelerator conditions. A motorized optical delay line was used in the system to compensate for phase errors. Described are error considerations and most important project issues like the hardware development and the real time phase controller software. The presented measurement results satisfy the design requirements. Experience gained during the experiments yielded proposals for system improvements.
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Fiber-optic link for the RF phase Reference Distribution system for the XFEL and TESLA projects
Photonics Applications in Astronomy Communications Industry and High-Energy Physics Experiments III, 2005Co-Authors: Krzysztof Czuba, Frank Eints, Matthias Felber, Stefan SimrockAbstract:The UV Free-Electron Laser (UVFEL) and The TeV-Energy Superconducting Linear Accelerator (TESLA) projects will require phase synchronization of 0.1 ps short term (millisecond), 1 ps short term (minutes) and 10 ps long term (days). The stringent synchronization requirement of 10fs was given for the X-Ray Free- Electron Laser (XFEL). To fufill this requirement the XFEL may use a fiber laser as Reference generator. But this requirement applies for a special location only, therefore the RF phase Reference Distribution system developed UVFEL and TESLA will also be used in the XFEL. The RF phase Reference Distribution system must deliver phase stable signals to hundreds of stations over a length of 33 km. Long, optical fiber based links are planned to be an important part of the entire Distribution system. This paper describes the concept of a long optical link, with a feedback system suppressing long term drifts of the RF signal phase. Stability requirements are given and most important design issues affecting system performance are discussed. Finally, an experimental setup and measurement results demonstrating system performance is shown.
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First Generation of Optical Fiber Phase Reference Distribution System for TESLA
2005Co-Authors: Krzysztof Czuba, Frank Eints, Matthias Felber, Stefan Simrock, Janusz Dobrowolski, Deutsches Elektronen-synchrotron DesyAbstract:1. ABSTRACT This report describes the design of a phase stable Fiber Optic (FO) link for the TESLA technology based projects. The concept of this long optical link, with a feedback system suppressing long term drifts of the RF signal phase is described. Stability requirements are given and most important design issues affecting the system performance are discussed. The technical design issues of system components like laser transmitter and optical phase shifter are described in detail. Last sections depict the software developed for system control and experimental results obtained after system was assembled.
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Design considerations for the RF phase Reference Distribution system for x-ray FEL and TESLA
2004Co-Authors: Krzysztof Czuba, Henning WeddigAbstract:ABSTRACT The RF Phase Reference Distribution System (PRDS) must deliver a highly RF phase stable signal to many various RFsubsystems of the X-ray Free Electron Laser (XFEL) and in the future the TESLA linear collider. The required phasesynchronization corresponding to the short term stability of ips must be guaranteed. Taking into consideration largeamount of devices to be synchronized, long distances and necessity of delivering different frequencies, the design ofPRDS becomes a very difficult and challenging task. This paper describes the main considered issues. Such parametersas Distribution frequency, waveguide attenuation, multiplier noise and temperature influence on the system are taken intoaccount. The advantages and disadvantages of coaxial cables and optical fiber as the Distribution medium are compared.The feedback system stabilizing long term phase drifts is presented and the structure of PRDS which may fulfill thedesign requirements is proposed.Keywords: FEL, TESLA, phase noise, frequency stability
Mariko Yamasaki - One of the best experts on this subject based on the ideXlab platform.
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Determining Young’s modulus of timber on the basis of a strength database and stress wave propagation velocity II: effect of the Reference Distribution database on the determination
Journal of Wood Science, 2010Co-Authors: Mariko Yamasaki, Yasutoshi Sasaki, Yasuo IijimaAbstract:A method of determining the Young’s modulus of timber using the stress wave propagation velocity without knowing the timber density was developed in our previous study. This method enables the estimation of Young’s modulus by Monte Carlo simulation using an existing database of the Young’s modulus versus density relationship as Reference. Here, in Part II, we consider the effect of the Reference Distribution database on the accuracy of the estimated Young’s modulus by the developed method. Twelve different Reference Distribution databases were used in this study, containing Young’s modulus versus density data for more than 13 000 real-size timber specimens of ten different species. We obtained the following results: (1) the Distribution of Young’s modulus estimated using an arbitrary stress wave propagation velocity depends on the Reference Distribution database employed, (2) the most important factor is not that the Reference database has data on the same species as the timber in the test, but rather that the Reference Distribution database covers the foreseeable range of timber densities within the test, and (3) the estimation accuracy is higher than about 80% when the database covers many species and has wide ranges of densities and Young’s moduli. This estimation method was developed in order to measure the Young’s modulus of timber whose density cannot be measured. Considering that the quality of lumber has a large variation, such estimation accuracy will be useful for practical applications.
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determining young s modulus of timber on the basis of a strength database and stress wave propagation velocity ii effect of the Reference Distribution database on the determination
Journal of Wood Science, 2010Co-Authors: Mariko Yamasaki, Yasutoshi Sasaki, Yasuo IijimaAbstract:A method of determining the Young’s modulus of timber using the stress wave propagation velocity without knowing the timber density was developed in our previous study. This method enables the estimation of Young’s modulus by Monte Carlo simulation using an existing database of the Young’s modulus versus density relationship as Reference. Here, in Part II, we consider the effect of the Reference Distribution database on the accuracy of the estimated Young’s modulus by the developed method. Twelve different Reference Distribution databases were used in this study, containing Young’s modulus versus density data for more than 13 000 real-size timber specimens of ten different species. We obtained the following results: (1) the Distribution of Young’s modulus estimated using an arbitrary stress wave propagation velocity depends on the Reference Distribution database employed, (2) the most important factor is not that the Reference database has data on the same species as the timber in the test, but rather that the Reference Distribution database covers the foreseeable range of timber densities within the test, and (3) the estimation accuracy is higher than about 80% when the database covers many species and has wide ranges of densities and Young’s moduli. This estimation method was developed in order to measure the Young’s modulus of timber whose density cannot be measured. Considering that the quality of lumber has a large variation, such estimation accuracy will be useful for practical applications.
Alex Dytso - One of the best experts on this subject based on the ideXlab platform.
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mmse bounds for additive noise channels under kullback leibler divergence constraints on the input Distribution
IEEE Transactions on Signal Processing, 2019Co-Authors: Alex Dytso, Abdelhak M. Zoubir, Michael Faus, Vincent H PoorAbstract:Upper and lower bounds on the minimum mean square error for additive noise channels are derived when the input Distribution is constrained to be close to a Gaussian Reference Distribution in terms of the Kullback–Leibler divergence. The upper bound is tight and is attained by a Gaussian Distribution whose mean is identical to that of the Reference Distribution and whose covariance matrix is defined implicitly via a system of non-linear equations. The estimator that attains the upper bound is identified as a minimax optimal estimator that is robust against deviations from the assumed prior. The lower bound provides an alternative to well-known inequalities in estimation and information theory—such as the Cramer–Rao lower bound, Stam's inequality, or the entropy power inequality—that is potentially tighter and defined for a larger class of input Distributions. Several examples of applications in signal processing and information theory illustrate the usefulness of the proposed bounds in practice.
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Tight MMSE Bounds for the AGN Channel Under KL Divergence Constraints on the Input Distribution
arXiv: Statistics Theory, 2018Co-Authors: Michael Fauss, Alex Dytso, Abdelhak M. Zoubir, H. Vincent PoorAbstract:Tight bounds on the minimum mean square error for the additive Gaussian noise channel are derived, when the input Distribution is constrained to be epsilon-close to a Gaussian Reference Distribution in terms of the Kullback--Leibler divergence. The Distributions that attain the bounds are shown be Gaussian whose means are identical to that of the Reference Distribution and whose covariance matrices are defined implicitly via systems of matrix equations. The estimator that attains the upper bound is identified as a minimax optimal estimator that is robust against deviations from the assumed prior. The lower bound is shown to provide a potentially tighter alternative to the Cramer--Rao bound. Both properties are illustrated with numerical examples.
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SSP - Tight MMSE Bounds for the AGN Channel Under KL Divergence Constraints on the Input Distribution
2018 IEEE Statistical Signal Processing Workshop (SSP), 2018Co-Authors: Michael Faub, Alex Dytso, Abdelhak M. Zoubir, H. Vincent PoorAbstract:Tight bounds on the minimum mean square error for the additive Gaussian noise channel are derived, when the input Distribution is constrained to be e-close to a Gaussian Reference Distribution in terms of the Kullback-Leibler divergence. The Distributions that attain the bounds are shown be Gaussian whose means are identical to that of the Reference Distribution and whose covariance matrices are defined implicitly via systems of matrix equations. The estimator that attains the upper bound is identified as a minimax optimal estimator that is robust against deviations from the assumed prior. The lower bound is shown to provide a potentially tighter alternative to the Cramer-Rao bound. Both properties are illustrated with numerical examples.
Shinichiro Michizono - One of the best experts on this subject based on the ideXlab platform.
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RF Reference Distribution system for J-PARC linac
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007Co-Authors: T. Kobayashi, E. Chishiro, S. Anami, S. Yamaguchi, Shinichiro MichizonoAbstract:Abstract The linac used by the Japan Proton Accelerator Research Complex (J-PARC) is a high-intensity proton linac with a peak current of 50 mA. The error in the accelerating field needs to be maintained within ±1% in amplitude and ±1° in phase. Thus, high phase stability is required for the RF Reference Distribution system. Our objective is to maintain the phase stability of the Reference to less than ±0.3°. The beam quality or intensity of a proton linac strongly depends on the stability of the accelerating fields of each cavity; therefore, the stability of the RF Reference Distribution system is essential for the performance of the J-PARC linac. A highly stable and unique RF Reference Distribution system was developed for the J-PARC linac. A 12-MHz RF Reference signal is converted into an optical signal and amplified by an optical amplifier. Then it is distributed through optical fiber links to 60 low-level RF control systems comprising klystron and solid-state amplifier driving systems. Phase-stabilized optical fiber (PSOF) is employed in the optical transfer line. The thermal coefficient of the PSOF transmission time was measured: its value was 0.4 ppm/°C. This property is insufficient for the required stability; accordingly, the temperature change in the PSOF should be controlled to be within ±0.5 °C by means of a cooling water system. New stable and low-jitter optical-to-electric (O/E) and electric-to-optical (E/O) converters were developed for this linac. The O/E converter is so compact that is can be mounted on a compact PCI board: its temperature is maintained constant by a Peltie device. A pulse driver (limiting amplifier) is introduced in the E/O and O/E converters for signal modulation to reduce the detection jitters. It transforms the 12-MHz signal into a rectangular wave: its the rise time is shorter than 200 ps. Then, a low-transfer jitter of 0.8 ps (rms) was obtained in the optical link of the E/O and O/E converters. The installation of the RF Reference Distribution system was completed. The phase stability of the distributed signal was evaluated, and a phase stability of the ±0.2° was obtained for a frequency of 927 MHz; consequently, the required system stability was achieved. The beam acceleration to a design energy of 181 MeV for the first phase (Phase I) was successfully performed in February 2007 and the centroid momentum fluctuation of the beam pulse was within ±0.015%, while the required stability was within ±0.025%. Now the beam commissioning has been steadily continued.
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PERFORMANCE OF RF Reference Distribution SYSTEM FOR THE J-PARC LINAC
2006Co-Authors: T. Kobayashi, E. Chishiro, Shinichiro Michizono, S.anami, S. YamaguchiAbstract:Installation of the J-PARC linac machines (Phase I) has been almost completed and the beam commissioning will be started in December this year. The error of the accelerating field must be within ±1o in phase and ±1% in amplitude. Thus, high phase stability is required as an RF Reference. Our objective concerning the phase stability of the Reference aims at less than ±0.3o. Last year the installation of the RF Reference Distribution system was completed. The Reference signal is optically distributed to all of the low-level RF control systems by using E/O, O/E, Optical Amplifier and Optical Couplers and so on. The performance of this system was evaluated. The phase stability of ±0.06o was obtained.
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RF Reference Distribution SYSTEM FOR THE 400-MEV PROTON LINAC OF THE KEK/JAERI JOINT PROJECT
2002Co-Authors: T. Kobayashi, E. Chishiro, S. Anami, S. Yamaguchi, Shinichiro MichizonoAbstract:For the high-intensity proton linac of the KEK/JAERI joint project, the error of the accelerating field must be within ± 1 degree in phase and ± 1% in amplitude. Thus, a high phase stability is required to the RF Reference Distribution system. A 12-MHz RF Reference is converted to an optical signal, and is distributed to 50 low-level RF control systems of klystron and solid-state amplifier stations through optical fiber links (E/O, O/E and optical fibers). Phase-stabilized optical fiber (PSOF) will be used as an optical transfer line. The characteristics of generalpurpose optical components (E/O, O/E, PSOF) were measured. Their performance is not sufficient to satisfy the requirements. New optimized E/O and O/E for this linac will thus be produced. The total stability of the RF Reference transfer system with new E/O and O/E will be evaluated.
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rf Reference Distribution system for the 400 mev proton linac of the kek jaeri joint project
2002Co-Authors: T. Kobayashi, E. Chishiro, S. Anami, S. Yamaguchi, Shinichiro MichizonoAbstract:For the high-intensity proton linac of the KEK/JAERI joint project, the error of the accelerating field must be within ± 1 degree in phase and ± 1% in amplitude. Thus, a high phase stability is required to the RF Reference Distribution system. A 12-MHz RF Reference is converted to an optical signal, and is distributed to 50 low-level RF control systems of klystron and solid-state amplifier stations through optical fiber links (E/O, O/E and optical fibers). Phase-stabilized optical fiber (PSOF) will be used as an optical transfer line. The characteristics of generalpurpose optical components (E/O, O/E, PSOF) were measured. Their performance is not sufficient to satisfy the requirements. New optimized E/O and O/E for this linac will thus be produced. The total stability of the RF Reference transfer system with new E/O and O/E will be evaluated.