Residual phase noise measurements of the input section in a receiver
Mavric, Uros; Chase, Brian; /Fermilab
2007-10-01
If not designed properly, the input section of an analog down-converter can introduce phase noise that can prevail over other noise sources in the system. In the paper we present residual phase noise measurements of a simplified input section of a classical receiver that is composed of various commercially available mixers and driven by an LO amplifier.
Wide-band residual phase-noise measurements on 40-GHz monolithic mode-locked lasers
Larsson, David; Hvam, Jørn Märcher
2005-01-01
We have performed wide-band residual phase-noise measurements on semiconductor 40-GHz mode-locked lasers by employing electrical waveguide components for the radio-frequency circuit. The intrinsic timing jitters of lasers with one, two, and three quantum wells (QW) are compared and our design...... prediction, concerning noise versus number of QWs, for the first time corroborated by experiments. A minimum jitter of 44 fs is found, by extrapolating to the Nyquist frequency, for the one-QW device having nearly transform-limited pulses of 1.2 ps. This jitter is nearly three times lower than for a three...
Olympus receiver evaluation and phase noise measurements
Campbell, Richard L.; Wang, Huailiang; Sweeney, Dennis
1990-01-01
A set of measurements performed by the Michigan Tech Sensing and Signal Processing Group on the analog receiver built by the Virginia Polytechnic Institute (VPI) and the Jet Propulsion Laboratory (JPL) for propagation measurements using the Olympus Satellite is described. Measurements of local oscillator (LO) phase noise were performed for all of the LOs supplied by JPL. In order to obtain the most useful set of measurements, LO phase noise measurements were made using the complete VPI receiver front end. This set of measurements demonstrates the performance of the receiver from the Radio Frequency (RF) input through the high Intermediate Frequency (IF) output. Three different measurements were made: LO phase noise with DC on the voltage controlled crystal oscillator (VCXO) port; LO phase noise with the 11.381 GHz LO locked to the reference signal generator; and a reference measurement with the JPL LOs out of the system.
Residual phase noise modeling of amplifiers using silicon bipolar transistors.
Theodoropoulos, Konstantinos; Everard, Jeremy
2010-03-01
In this paper, we describe the modeling of residual 1/f phase noise for Si bipolar amplifiers operating in the linear region. We propose that for Si bipolar amplifiers, the 1/f phase noise is largely caused by the base emitter recombination flicker noise. The up-conversion mechanism is described through linear approximation of the phase variation of the amplifier phase response by the variation of the device parameters (C(b)c, C(be), g(m), r(e)) caused by the recombination 1/f noise. The amplifier phase response describes the device over the whole frequency range of operation for which the influence of the poles and zeros is investigated. It is found that for a common emitter amplifier it is sufficient to only incorporate the effect of the device poles to describe the phase noise behavior over most of its operational frequency range. Simulations predict the measurements of others, including the flattening of the PM noise at frequencies beyond f(3dB), not predicted by previous models.
A Gaussian measure of quantum phase noise
Schleich, Wolfgang P.; Dowling, Jonathan P.
1992-01-01
We study the width of the semiclassical phase distribution of a quantum state in its dependence on the average number of photons (m) in this state. As a measure of phase noise, we choose the width, delta phi, of the best Gaussian approximation to the dominant peak of this probability curve. For a coherent state, this width decreases with the square root of (m), whereas for a truncated phase state it decreases linearly with increasing (m). For an optimal phase state, delta phi decreases exponentially but so does the area caught underneath the peak: all the probability is stored in the broad wings of the distribution.
Hong, Jun; Liu, An-min; Guo, Jian
2013-08-01
An analytic model for an injection-locked dual-loop optoelectronic oscillator (OEO) is proposed and verified by experiments in this paper. Based on this theoretical model, the effect of injection power on the single-sideband phase noise of the OEO is analyzed, and results suggest that moderate injection is one key factor for a balance between phase noise and spur for OEO. In order to measure superlow phase noise of OEOs, a cross-correlation measurement system based on the fiber delay line is built, in which high linear photodetector and low-phase-noise amplifier are used to improve systematic sensitivity. The cross-correlation measurement system is validated by experiments, and its noise floor for the X band is about -130 dBc/Hz at 1 kHz and -168 dBc/Hz at 10 kHz after a cross correlation of 200 times.
Residual Phase Noise and Time Jitters of Single-Chip Digital Frequency Dividers
Lu-Lu Yan; Sen Meng; Wen-Yu Zhao; Wen-Ge Guo; Hai-Feng Jiang; Shou-Gang Zhang
2015-01-01
Abstract-In this paper, we demonstrate the residual phase noise of a few microwave frequency dividers which usually limit the performance of frequency synthesizers. In order to compare these dividers under different operation frequencies, we calculate additional time jitters of these dividers by using the measured phase noise. The time jitters are various from ~0.1fs to 43fs in a bandwidth from 1Hz to 100Hz in dependent of models and operation frequencies. The HMC series frequency dividers exhibit outstanding performance for high operation frequencies, and the time jitters can be sub-fs. The time jitters of SP8401, MC10EP139, and MC100LVEL34 are comparable or even below that of HMC series for low operation frequencies.
Kuse, N; Fermann, M E
2017-06-06
Recent progress in ultra low phase noise microwave generation indispensably depends on ultra low phase noise characterization systems. However, achieving high sensitivity currently relies on time consuming averaging via cross correlation, which sometimes even underestimates phase noise because of residual correlations. Moreover, extending high sensitivity phase noise measurements to microwaves beyond 10 GHz is very difficult because of the lack of suitable high frequency microwave components. In this work, we introduce a delayed self-heterodyne method in conjunction with sensitivity enhancement via the use of higher order comb modes from an electro-optic comb for ultra-high sensitivity phase noise measurements. The method obviates the need for any high frequency RF components and has a frequency measurement range limited only by the bandwidth (100 GHz) of current electro-optic modulators. The estimated noise floor is as low as -133 dBc/Hz, -155 dBc/Hz, -170 dBc/Hz and -171 dBc/Hz without cross correlation at 1 kHz, 10 kHz, 100 kHz and 1 MHz Fourier offset frequency for a 10 GHz carrier, respectively. Moreover, since no cross correlation is necessary, RF oscillator phase noise can be directly suppressed via feedback up to 100 kHz frequency offset.
Pnev, A B; Dvoretskiy, D A; Zhirnov, A A; Nesterov, E T; Sazonkin, S G; Chernutsky, A O; Shelestov, D A; Fedorov, A K; Svelto, C; Karasik, V E
2016-01-01
We propose a novel scheme for laser phase noise measurements with minimized sensitivity to external fluctuations including interferometer vibration, temperature instability, other low-frequency noise, and relative intensity noise. In order to minimize the effect of these external fluctuations, we employ simultaneous measurement of two spectrally separated channels in the scheme. We present an algorithm for selection of the desired signal to extract the phase noise. Experimental results demonstrate potential of the suggested scheme for a wide range of technological applications.
Estimation of MIMO channel capacity from phase-noise impaired measurements
Pedersen, Troels; Yin, Xuefeng; Fleury, Bernard Henri
2008-01-01
phase noise samples affecting measurement samples collected with real TDMMIMO channel sounders are correlated. In this contribution a capacity estimator that accounts for the phase noise correlation is proposed. The estimator is based on a linear minimum mean square error estimate of the MIMO channel...
Measurement of Allan variance and phase noise at fractions of a millihertz
Conroy, Bruce L.; Le, Duc
1990-01-01
Although the measurement of Allan variance of oscillators is well documented, there is a need for a simplified system for finding the degradation of phase noise and Allan variance step-by-step through a system. This article describes an instrumentation system for simultaneous measurement of additive phase noise and degradation in Allan variance through a transmitter system. Also included are measurements of a 20-kW X-band transmitter showing the effect of adding a pass tube regulator.
Modeling and Measurement of Phase Noise in GaAs HBT Ka-Band Oscillators
Lenk, Friedrich; Schott, Matthias; Heinrich, Wolfgang
2001-01-01
Accurate oscillator phase-noise simulation is a key problem in MMIC design, which is not solved satisfactory so far and needs further investigation. In this paper, a Ka-band MMIC oscillator with GaInP/GaAs HBT and on-chip resonator is treated as an example. Measured phase noise reaches -90 dBc/Hz and below at 100 kHz offset. To evaluate phase-noise predic-tion, the circuit is simulated using different commercial simulation tools and HBT models. Con-siderable differences in simulation results ...
A method of measurement of the phase noise of stable oscillators by use of FFT technique
Hahn, Stefan; Hussain, Sabah
A method of measurement of the power density spectrum of phase noise of stable oscillators is presented. The oscillator under test and the reference are beating with a very low beat frequency. So the use of the phase locking loop is avoided. The time gated phase noise is converted into a digital signal and an FFT algoritm is used to compute the power spectrum. The experimental verification of the method is presented.
Pagnanelli, Christopher J.; Cashin, William F.
1992-01-01
The characterization of precision frequency standard phase noise and spurious outputs is addressed, using the two-oscillator coherent downconversion technique. Focus is on techniques for making accurate measurements of phase noise and spurious outputs within 100 KHz of a carrier. Significant sources of measurement error related to hardware design problems and inadequate measurement procedures are discussed: measurement errors resulting from system noise sources, phase-locked loop effects, and system bandwidth limitations. In addition, methods and design considerations for minimizing the effects of such errors are presented. Analytic discussions and results are supplemented with actual test data and measurements made using measurement hardware developed at the Ball Corporation, Efratom Division.
Zhu, Dengjian; Zhang, Fangzheng; Zhou, Pei; Pan, Shilong
2015-04-01
An approach for phase noise measurement of microwave signal sources based on a microwave photonic frequency down-converter is proposed. Using the same optical carrier, the microwave signal under test is applied to generate two +1st-order optical sidebands by two stages of electro-optical modulations. A time delay is introduced between the two sidebands through a span of fiber. By beating the two +1st-order sidebands at a photodetector, frequency down-conversion is implemented, and phase noise of the signal under test can be calculated thereafter. The system has a very large operation bandwidth thanks to the frequency conversion in the optical domain, and good phase noise measurement sensitivity can be achieved since the signal degradation caused by electrical amplifiers is avoided. An experiment is carried out. The phase noise measured by the proposed system agrees well with that measured by a commercial spectrum analyzer or provided by the datasheet. A large operation bandwidth of 5-40 GHz is demonstrated using the proposed system. Moreover, good phase noise floor is achieved (-123 dBc/Hz at 1 kHz and -137 dBc/Hz at 10 kHz at 10 GHz), which is nearly constant over the full measurement range.
Photonic Delay-line Phase Noise Measurement System
2011-09-01
combined 500-m and 6-km delay-line measurement system. Noise floor data are shown for the system with and without an EDFA . The laser power was 10 dBm...The optical power into the photodiode was 0 dBm without the EDFA and 11 dBm with it...data are shown for the system with and without an EDFA as well as with a high-power laser. The output optical powers of the low and high-power
Phase noise measurement of high-power fiber amplifiers
Hu Xiao; Xiaolin Wang; Yanxing Ma; Bing He; Pu Zhou; Jun Zhou; Xiaojun Xu
2011-01-01
We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique. Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an amplifier, whereas the high frequency components related to laser power affect the control bandwidth. The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9 kHz under the output power of 25,55, 125, and 180W, respectively. The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.%@@ We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique.Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an am-plifier, whereas the high frequency components related to laser power affect the control bandwidth.The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9kHz under the output power of 25, 55, 125, and 180 W, respectively.The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.
Modeling phase noise in multifunction subassemblies.
Driscoll, Michael
2012-03-01
Obtaining requisite phase noise performance in hardware containing multifunction circuitry requires accurate modeling of the phase noise characteristics of each signal path component, including both absolute (oscillator) and residual (non-oscillator) circuit contributors. This includes prediction of both static and vibration-induced phase noise. The model (usually in spreadsheet form) is refined as critical components are received and evaluated. Additive (KTBF) phase noise data can be reasonably estimated, based on device drive level and noise figure. However, accurate determination of component near-carrier (multiplicative) and vibration-induced noise usually must be determined via measurement. The model should also include the effects of noise introduced by IC voltage regulators and properly discriminate between common versus independent signal path residual noise contributors. The modeling can be easily implemented using a spreadsheet.
Phase-Noise and Amplitude-Noise Measurement of Low-Power Signals
Rubiola, Enrico; Salik, Ertan; Yu, Nan; Maleki, Lute
2004-01-01
Measuring the phase fluctuation between a pair of low-power microwave signals, the signals must be amplified before detection. In such cases the phase noise of the amplifier pair is the main cause of 1/f background noise of the instrument. this article proposes a scheme that makes amplification possible while rejecting the close in 1/f (flicker) noise of the two amplifiers. Noise rejection, which relies upon the understanding of the amplifier noise mechanism does not require averaging. Therefore, our scheme can also be the detector of a closed loop noise reduction system. the first prototype, compared to a traditional saturated mixer system under the same condition, show a 24 dB noise reduction of the 1/f region.
Phase noise measurements of the 400-kW, 2.115-GHz (S-band) transmitter
Boss, P.; Hoppe, D.; Bhanji, A.
1987-01-01
The measurement theory is described and a test method to perform phase noise verification using off-the-shelf components and instruments is presented. The measurement technique described consists of a double-balanced mixer used as phase detector, followed by a low noise amplifier. An FFT spectrum analyzer is then used to view the modulation components. A simple calibration procedure is outlined that ensures accurate measurements. A block diagram of the configuration is presented as well as actual phase noise data from the 400 kW, 2.115 GHz (S-band) klystron transmitter.
Kan WU; Shum, Ping
2010-01-01
The phase noise and intensity noise of a pulse train are theoretically analyzed in the demodulation measurement. The effect of pulse asymmetry is discussed for the first time using Fourier series. Experimentally, photodetectors with different bandwidth and incident power levels are compared to achieve minimum pulse distortion.
A New Phase Noise Detection Method
Yan, Gangfeng
2015-01-01
Phase noise is one of the most important parameters in many oscillators. Detecting accurately phase noise for oscillators has importance significance. In this paper, based on correlation operation detection phase noise for oscillators was proposed. This method not only can save a high precision reference oscillator, but also can detect accurately the phase noise of measured oscillator in theory. Detected phase noise of oscillators using this method has very strong utility value.
A simple technique for high resolution time domain phase noise measurement
Reinhardt, V. S.; Donahoe, T.
1977-01-01
A new time domain phase comparator is described. The device uses a novel technique to allow time domain phase measurements to be made with period and time interval counters without the use of offset reference oscillators. The device uses a single reference oscillator and allows measurements with a phase resolution greater than the noise floor of the reference. Data is presented showing a phase resolution of 0.02ps at 5 MHz with a crystal reference. The device has application in measuring the phase stability of systems where approximate phase quadrature can be maintained.
Giordano, V.; Grop, S.; Fluhr, C.; Dubois, B.; Kersalé, Y.; Rubiola, E.
2016-06-01
The Cryogenic Sapphire Oscillator (CSO) is the microwave oscillator which feature the highest short-term stability. Our best units exhibit Allan deviation σy (τ) of 4.5x10-16 at 1s, ≈ 1.5x10-16 at 100 s ≤ t ≤ 5,000 s (floor), and ≤ 5x10-15 at one day. The use of a Pulse-Tube cryocooler enables full two year operation with virtually no maintenance. Starting with a short history of the CSO in our lab, we go through the architecture and we provide more details about the resonator, the cryostat, the oscillator loop, and the servo electronics. We implemented three similar oscillators, which enable the evaluation of each with the three- cornered hat method, and provide the potential for Allan deviation measurements at parts of 10-17 level. One of our CSOs (ULISS) is transportable, and goes with a small customized truck. The unique feature of ULISS is that its σy (τ) can be validated at destination by measuring before and after the roundtrip. To this extent, ULISS can be regarded as a traveling standard of frequency stability. The CSOs are a part of the Oscillator IMP project, a platform dedicated to the measurement of noise and short-term stability of oscillators and devices in the whole radio spectrum (from MHz to THz), including microwave photonics. The scope spans from routine measurements to the research on new oscillators, components, and measurement methods.
Qi, Bing; Lo, Hoi-Kwong; Qian, Li
2009-01-01
In this paper, we present a high speed random number generation scheme based on measuring the quantum phase noise of a single mode diode laser operating at a low intensity level near the lasing threshold. A delayed self-heterodyning system has been developed to measure the random phase fluctuation. We experimentally investigate this random number generation scheme under two different operating conditions: with or without active phase stabilization of the fiber interferometer in the self-heterodyning system. The achieved random number generation rates are 500Mbit/s and 50Mbit/s, respectively. The generated random numbers have passed all the DIEHARD tests.
Huang, Xianhe; Chen, Pingping; Fu, Wei; Jiao, Junjie
2015-09-01
To predict the phase noise in an 80-MHz crystal oscillator, on the basis of the classical Leeson model, we analyzed and selected the oscillator noise figure F and transistor corner frequency fc reasonably, and then calculated the loaded Q (QL) value of the oscillator according to the parameters in the selected Butler oscillation circuit. Thus, we obtained the predicted phase noise in an 80-MHz crystal oscillator according to the Leeson phase noise formula. Next, the simulation curve of the phase noise in this 80-MHz low-phase-noise crystal oscillator was obtained by establishing a transistor nonlinear model using commercial design software. Then, we debugged the 80-MHz low-phase-noise crystal oscillator prototype under the guidance of the prediction and simulation results and tested it. The measured results show that the phase noise predicted after selecting reasonable parameters for the Leeson model and the ADS simulation curve of the phase noise obtained by using the nonlinear transistor model are both close to the actual measured result. This result may be beneficial in simplifying the design process for low-phase-noise crystal oscillators.
Ezeilo, A.N.; Webster, G.A. [Imperial College, London (United Kingdom); Webster, P.J. [Salford Univ. (United Kingdom)
1997-04-01
Because neutrons can penetrate distances of up to 50 mm in most engineering materials, this makes them unique for establishing residual-stress distributions non-destructively. D1A is particularly suited for through-surface measurements as it does not suffer from instrumental surface aberrations commonly found on multidetector instruments, while D20 is best for fast internal-strain scanning. Two examples for residual-stress measurements in a shot-peened material, and in a weld are presented to demonstrate the attractive features of both instruments. (author).
Oscillator With Low Phase Noise
Kleinberg, Leonard L.
1987-01-01
Phase errors cancelled for high frequency stability. Radio-frequency oscillator achieves high stability of frequency through parallel, two-amplifier configuration in which effects cause phase noise tend to cancel each other. Circuit includes two amplifiers with resonating elements, each constitutes part of feedback loop of other. Generate same frequency because each circuit provides other with conditions necessary for oscillation.
锁相环在相位噪声测试中的工作机理和影响%Principle and Effect of the Phase Lock Loop in Phase Noise Measurement
刘红春; 刘红运
2009-01-01
分析了相位检波技术测试相位噪声的工作原理和锁相环在电路中的工作机理,给出了锁相环对相位噪声测试影响的转移函数,通过对环路修正前和修正后的实际测试曲线的比较,很容易看出环路噪声压缩的影响.明确了在实际测试中,必须对锁相环带宽内的相位噪声曲线进行修正.通过分析可以看出,用相位检波器方法使相位噪声测试由测信号相位起伏变成测电压起伏,用锁相技术使压控参考源与被测源同频,并可有效地对锁相带宽内噪声抑制进行修正,改进了相位噪声测试的方法.%The operation principle of phase detector measuring phase noise and the mechanism of the phase lock loop (PLL) in the circuit were analyzed. The PLL phase noise transfer function was given, and the effect of PLL phase noise compression was observed through the comparison of corrected and uncorrected phase noise curves within PLL BW. The results show that phase noise curves must be corrected within PLL BW, voltage fluctuations transform into combined phase fluctuations at two input sources with the phase detector, and the error voltage out of the phase lock loop is applied to one of the sources, forcing it to track the other in phase with PLL. Besides that the phase noise can be corrected effectively within PLL BW, thus improving the phase noise measurement.
PHASE NOISE COMPARISON OF SHORT PULSE LASER SYSTEMS
Shukui Zhang; Stephen Benson; John Hansknecht; David Hardy; George Neil; Michelle D. Shinn
2006-08-27
This paper describes phase noise measurements of several different laser systems that have completely different gain media and configurations including a multi-kW free-electron laser. We will focus on state-of-the-art short pulse lasers, especially drive lasers for photocathode injectors. Phase noise comparison of the FEL drive laser, electron beam and FEL laser output also will be presented.
Phase Noise Comparision of Short Pulse Laser Systems
S. Zhang; S. V. Benson; J. Hansknecht; D. Hardy; G. Neil; Michelle D. Shinn
2006-12-01
This paper describes the phase noise measurement on several different mode-locked laser systems that have completely different gain media and configurations including a multi-kW free-electron laser. We will focus on the state of the art short pulse lasers, especially the drive lasers for photocathode injectors. A comparison between the phase noise of the drive laser pulses, electron bunches and FEL pulses will also be presented.
Dual correlated pumping scheme for phase noise preservation in all-optical wavelength conversion.
Anthur, Aravind P; Watts, Regan T; Shi, Kai; Carroll, John O'; Venkitesh, Deepa; Barry, Liam P
2013-07-01
We study the effect of transfer of phase noise in different four wave mixing schemes using a coherent phase noise measurement technique. The nature of phase noise transfer from the pump to the generated wavelengths is shown to be independent of the type of phase noise (1 / f or white noise frequency components). We then propose a novel scheme using dual correlated pumps to prevent the increase in phase noise in the conjugate wavelengths. The proposed scheme is experimentally verified by the all-optical wavelength conversion of a DQPSK signal at 10.7 GBaud.
Uncorrelated Phase Noise Analysis for Millimeter-Wave Radiometer Imager Frequency Synthesizer
Jin Zhang
2013-09-01
Full Text Available In this paper, a nontrivial uncorrelated phase noise analysis is proposed for frequency synthesizer of a passive millimeter-wave Synthetic Aperture Interferometric Radiometer (SAIR imager named BHU-2D-U designed for concealed weapon detections on human bodies with high imaging rates. This synthesizer provides local oscillators both for millimeter-wave front-ends and intermediate frequency IQ demodulators for the receivers. The influence of synthesizer uncorrelated phase noise in different offset frequency ranges on the visibility phase errors have been systematically investigated with phase noise mismatch requirements drawn. Integrated RMS phase error has been applied to establish uncorrelated phase noise requirements for visibility error control. Measurement results have proved that uncorrelated phase noise does exist among synthesizer output pairs, and the previously defined requirements are achieved with imaging results proposed. In conclusion, the uncorrelated phase noise effects on SAIR visibility errors have been concretized to phase noise design requirements, which have been realized by synthesizer design.
Phase noise of whispering gallery photonic hyper-parametric microwave oscillators.
Savchenkov, Anatoliy A; Rubiola, Enrico; Matsko, Andrey B; Ilchenko, Vladimir S; Maleki, Lute
2008-03-17
We report on the experimental study of phase noise properties of a high frequency photonic microwave oscillator based on four wave mixing in calcium fluoride whispering gallery mode resonators. Specifically, the oscillator generates approximately 8.5 GHz signals with -120 dBc/Hz at 100 kHz from the carrier. The floor of the phase noise is limited by the shot noise of the signal received at the photodetector. We argue that the performance of the oscillator can be significantly improved if one uses extremely high finesse resonators, increases the input optical power, supersaturates the oscillator, and suppresses the residual stimulated Raman scattering in the resonator. We also disclose a method of extremely sensitive measurement of the integral dispersion of millimeter scale dielectric resonators.
Phase Noise Influence in Optical OFDM Systems employing RF Pilot Tone for Phase Noise Cancellation
Jacobsen, Gunnar; Kazovsky, Leonid G.; Xu, TianHua; Popov, Sergei; Li, Jie; Zhang, Yimo; Friberg, Ari T.
2016-01-01
For coherent and direct-detection Orthogonal Frequency Division Multiplexed (OFDM) systems employing radio frequency (RF) pilot tone phase noise cancellation the influence of laser phase noise is evaluated. Novel analytical results for the common phase error and for the (modulation dependent) inter carrier interference are evaluated based upon Gaussian statistics for the laser phase noise. In the evaluation it is accounted for that the laser phase noise is filtered in the correlation signal d...
Robust terahertz self-heterodyne system using a phase noise compensation technique.
Song, Hajun; Song, Jong-In
2015-08-10
We propose and demonstrate a robust terahertz self-heterodyne system using a phase noise compensation technique. Conventional terahertz self-heterodyne systems suffer from degraded phase noise performance due to phase noise of the laser sources. The proposed phase noise compensation technique uses an additional photodiode and a simple electric circuit to produce phase noise identical to that observed in the terahertz signal produced by the self-heterodyne system. The phase noise is subsequently subtracted from the terahertz signal produced by the self-heterodyne system using a lock-in amplifier. While the terahertz self-heterodyne system using a phase noise compensation technique offers improved phase noise performance, it also provides a reduced phase drift against ambient temperature variations. The terahertz self-heterodyne system using a phase noise compensation technique shows a phase noise of 0.67 degree in terms of a standard deviation value even without using overall delay balance control. It also shows a phase drift of as small as approximately 10 degrees in an open-to-air measurement condition without any strict temperature control.
Microwave Oscillator Would Have Reduced Phase Noise
Dick, G. John; Saunders, Jon
1991-01-01
Microwave oscillators of proposed new type incorporate suppressed-carrier/negative-feedback feature to reduce phase noise near their carrier frequencies. Concept results in phase noise less than achievable by cryogenically stabilized microwave components or by room-temperature oscillators stabilized by quartz crystals. Implemented in three different versions.
Phase noise in RF and microwave amplifiers.
Boudot, Rodolphe; Rubiola, Enrico
2012-12-01
Understanding amplifier phase noise is a critical issue in many fields of engineering and physics, such as oscillators, frequency synthesis, telecommunication, radar, and spectroscopy; in the emerging domain of microwave photonics; and in exotic fields, such as radio astronomy, particle accelerators, etc. Focusing on the two main types of base noise in amplifiers, white and flicker, the power spectral density of the random phase φ(t) is Sφ(f) = b(0) + b(-1)/f. White phase noise results from adding white noise to the RF spectrum in the carrier region. For a given RF noise level, b(0) is proportional to the reciprocal of the carrier power P(0). By contrast, flicker results from a near-dc 1/f noise-present in all electronic devices-which modulates the carrier through some parametric effect in the semiconductor. Thus, b(-1) is a parameter of the amplifier, constant in a wide range of P(0). The consequences are the following: Connecting m equal amplifiers in parallel, b(-1) is 1/m times that of one device. Cascading m equal amplifiers, b(-1) is m times that of one amplifier. Recirculating the signal in an amplifier so that the gain increases by a power of m (a factor of m in decibels) as a result of positive feedback (regeneration), we find that b(-1) is m(2) times that of the amplifier alone. The feedforward amplifier exhibits extremely low b(-1) because the carrier is ideally nulled at the input of its internal error amplifier. Starting with an extensive review of the literature, this article introduces a system-oriented model which describes the phase flickering. Several amplifier architectures (cascaded, parallel, etc.) are analyzed systematically, deriving the phase noise from the general model. There follow numerous measurements of amplifiers using different technologies, including some old samples, and in a wide frequency range (HF to microwaves), which validate the theory. In turn, theory and results provide design guidelines and give suggestions for CAD and
A uniform phase noise QVCO with a feedback current source
Zhou Chunyuan; Zhang Lei; Qian He
2012-01-01
A novel integrated quadrature voltage controlled oscillator (QVCO) with a feedback current source is presented in this paper.Benefiting from the current adjusting function of the feedback current source,the proposed QVCO exhibits a uniform phase noise over the entire tuning range.This QVCO is implemented in 65-nm CMOS technology.The measurement results show that it draws less than 3-mA average current from a 1.2-V supply and the phase noise is less than -110 dBc/Hz @1MHz offset over the entire tuning range.The fluctuation of phase noise @l MHz offset from the center frequency of 2 84-GHz to 3.27-GHz is less than 1 dBc/Hz,which validates the correctness of the proposed current source feedback technique.
Interferometric Measurement Of Residual Stress
Danyluk, Steven; Andonian, A. T.
1990-01-01
Stress averaged through thickness of plate measured nondestructively. Theory of elasticity combined with laser interferometric technique into technique for measurement of residual stresses in solid objects - usually in thin, nominally-flat plates. Measurements particularly useful in inspection of wafers of single-crystal silicon for making solar cells or integrated circuits, because stresses remaining after crystal-growing process cause buckling or fracture. Used to predict deflections of plates caused by known applied loads under specified boundary condition, or to infer applied loads that cause known deflections. Also used to relate known deflections to residual stresses equivalent to stresses produced by fictitious applied loads.
François, B; Calosso, C E; Danet, J M; Boudot, R
2014-09-01
We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad(2)/Hz and -129 dB rad(2)/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10(-14) at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.
Phase Noise Reduction of Laser Diode
Zhang, T. C.; Poizat, J.-Ph.; Grelu, P.; Roch, J.-F.; Grangier, P.; Marin, F.; Bramati, A.; Jost, V.; Levenson, M. D.; Giacobino, E.
1996-01-01
Phase noise of single mode laser diodes, either free-running or using line narrowing technique at room temperature, namely injection-locking, has been investigated. It is shown that free-running diodes exhibit very large excess phase noise, typically more than 80 dB above shot-noise at 10 MHz, which can be significantly reduced by the above-mentioned technique.
Phase noise suppression through parametric filtering
Cassella, Cristian; Strachan, Scott; Shaw, Steven W.; Piazza, Gianluca
2017-02-01
In this work, we introduce and experimentally demonstrate a parametric phase noise suppression technique, which we call "parametric phase noise filtering." This technique is based on the use of a solid-state parametric amplifier operating in its instability region and included in a non-autonomous feedback loop connected at the output of a noisy oscillator. We demonstrate that such a system behaves as a parametrically driven Duffing resonator and can operate at special points where it becomes largely immune to the phase fluctuations that affect the oscillator output signal. A prototype of a parametric phase noise filter (PFIL) was designed and fabricated to operate in the very-high-frequency range. The PFIL prototype allowed us to significantly reduce the phase noise at the output of a commercial signal generator operating around 220 MHz. Noise reduction of 16 dB (40×) and 13 dB (20×) were obtained, respectively, at 1 and 10 kHz offsets from the carrier frequency. The demonstration of this phase noise suppression technique opens up scenarios in the development of passive and low-cost phase noise cancellation circuits for any application demanding high quality frequency generation.
Electromechanical Apparatus Measures Residual Stress
Chern, Engmin J.; Flom, Yury
1993-01-01
Nondestructive test exploits relationship between stress and eddy-current-probe resistance. Yields data on residual stress or strain in metal tension/compression specimen (stress or strain remaining in specimen when no stress applied from without). Apparatus is assembly of commercial equipment: tension-or-compression testing machine, eddy-current probe, impedance gain-and-phase analyzer measuring impedance of probe coil, and desktop computer, which controls other equipment and processes data received from impedance gain-and-phase analyzer.
Broadband phase noise suppression in a Yb-fiber frequency comb.
Cingöz, A; Yost, D C; Allison, T K; Ruehl, A; Fermann, M E; Hartl, I; Ye, J
2011-03-01
We report a simple technique to suppress high-frequency phase noise of a Yb-based fiber optical frequency comb using an active intensity noise servo. Out-of-loop measurements of the phase noise using an optical heterodyne beat with a cw laser show suppression of phase noise by ≥7 dB out to Fourier frequencies of 100 kHz with a unity-gain crossing of ∼700 kHz. These results are enabled by the strong correlation between the intensity and phase noise of the laser. Detailed measurements of intensity and phase noise spectra, as well as transfer functions, reveal that the dominant phase and intensity noise contribution above ∼100 kHz is due to amplified spontaneous emission or other quantum noise sources.
Phase noise and frequency stability in oscillators
Rubiola, Enrico
2009-01-01
Presenting a comprehensive account of oscillator phase noise and frequency stability, this practical text is both mathematically rigorous and accessible. An in-depth treatment of the noise mechanism is given, describing the oscillator as a physical system, and showing that simple general laws govern the stability of a large variety of oscillators differing in technology and frequency range. Inevitably, special attention is given to amplifiers, resonators, delay lines, feedback, and flicker (1/f) noise. The reverse engineering of oscillators based on phase-noise spectra is also covered, and end-of-chapter exercises are given. Uniquely, numerous practical examples are presented, including case studies taken from laboratory prototypes and commercial oscillators, which allow the oscillator internal design to be understood by analyzing its phase-noise spectrum. Based on tutorials given by the author at the Jet Propulsion Laboratory, international IEEE meetings, and in industry, this is a useful reference for acade...
Phase noise characterization of sub-hertz linewidth lasers via digital cross correlation
Xie, Xiaopeng; Bouchand, Romain; Nicolodi, Daniele; Lours, Michel; Alexandre, Christophe; Le Coq, Yann
2017-04-01
Phase noise or frequency noise is a key metrics to evaluate the short term stability of a laser. This property is of a great interest for the applications but delicate to characterize, especially for narrow line-width lasers. In this letter, we demonstrate a digital cross correlation scheme to characterize the absolute phase noise of sub-hertz line-width lasers. Three 1,542 nm ultra-stable lasers are used in this approach. For each measurement two lasers act as references to characterize a third one. Phase noise power spectral density from 0.5 Hz to 0.8 MHz Fourier frequencies can be derived for each laser by a mere change in the configuration of the lasers. This is the first time showing the phase noise of sub-hertz line-width lasers with no reference limitation. We also present an analysis of the laser phase noise performance.
Multipurpose exciter with low phase noise
Conroy, B.; Le, D.
1989-01-01
Results of an effort to develop a lower-cost exciter with high stability, low phase noise, and controllable phase and frequency for use in Deep Space Network and Goldstone Solar System Radar applications are discussed. Included is a discussion of the basic concept, test results, plans, and concerns.
Sthal, Fabrice; Salzenstein, Patrice; Galliou, Serge; Cibiel, Gilles; Rubiola, Enrico
2007-01-01
High-stability quartz oscillators are needed in a number of space applications. A short-term stability of parts in 10^{-14} [Allan deviation \\sigma y(\\tau) ] is sometimes required, for integration time \\tau of approximately 1-10 s. The Centre National d'Etudes Spatiales (CNES) and the FEMTO-ST Institute (formerly LPMO and LCEP), have been collaborating for many years in this domain, aiming at measuring and at understanding the oscillator noise. The highest stability has been observed on 5 MHz and 10 MHz bulk acoustic-wave resonators. Yet this stability is still not sufficient, or the the manufacturing method is not reproducible. Recently, the analysis of a few premium-stability oscillators has demonstrated that the oscillator frequency instability is due to the fluctuation of the resonator natural frequency, rather than to the noise of the sustaining amplifier via the Leeson effect. It is therefore natural to give attention to the measurement of the resonator fluctuations.
Phase Noise Influence in Optical OFDM Systems employing RF Pilot Tone for Phase Noise Cancellation
Jacobsen, Gunnar; Kazovsky, Leonid G.; Xu, Tianhua; Popov, Sergei; Li, Jie; Zhang, Yima; Friberg, Ari T.
2011-06-01
For coherent and direct-detection Orthogonal Frequency Division Multiplexed (OFDM) systems employing radio frequency (RF) pilot tone phase noise cancellation the influence of laser phase noise is evaluated. Novel analytical results for the common phase error and for the (modulation dependent) inter carrier interference are evaluated based upon Gaussian statistics for the laser phase noise. In the evaluation it is accounted for that the laser phase noise is filtered in the correlation signal detection. Numerical results are presented for OFDM systems with 4 and 16 PSK modulation, 200 OFDM bins and baud rate of 1 GS/s. It is found that about 225 km transmission is feasible for the coherent 4PSK-OFDM system over normal (G.652) fiber.
Phase Noise Influence in Optical OFDM Systems employing RF Pilot Tone for Phase Noise Cancellation
Jacobsen, Gunnar; Xu, Tianhua; Popov, Sergei; Li, Jie; Zhang, Yimo; Friberg, Ari T
2016-01-01
For coherent and direct-detection Orthogonal Frequency Division Multiplexed (OFDM) systems employing radio frequency (RF) pilot tone phase noise cancellation the influence of laser phase noise is evaluated. Novel analytical results for the common phase error and for the (modulation dependent) inter carrier interference are evaluated based upon Gaussian statistics for the laser phase noise. In the evaluation it is accounted for that the laser phase noise is filtered in the correlation signal detection. Numerical results are presented for OFDM systems with 4 and 16 PSK modulation, 200 OFDM bins and baud rate of 1 GS/s. It is found that about 225 km transmission is feasible for the coherent 4PSK-OFDM system over normal (G.652) fiber.
A Low Power Low Phase Noise Oscillator for MICS Transceivers.
Li, Dawei; Liu, Dongsheng; Kang, Chaojian; Zou, Xuecheng
2017-01-12
A low-power, low-phase-noise quadrature oscillator for Medical Implantable Communications Service (MICS) transceivers is presented. The proposed quadrature oscillator generates 349~689 MHz I/Q (In-phase and Quadrature) signals covering the MICS band. The oscillator is based on a differential pair with positive feedback. Each delay cell consists of a few transistors enabling lower voltage operation. Since the oscillator is very sensitive to disturbances in the supply voltage and ground, a self-bias circuit for isolating the voltage disturbance is proposed to achieve bias voltages which can track the disturbances from the supply and ground. The oscillation frequency, which is controlled by the bias voltages, is less sensitive to the supply and ground noise, and a low phase noise is achieved. The chip is fabricated in the UMC (United Microelectronics Corporation) 0.18 μm CMOS (Complementary Metal Oxide Semiconductor) process; the core just occupies a 28.5 × 22 μm² area. The measured phase noise is -108.45 dBc/Hz at a 1 MHz offset with a center frequency of 540 MHz. The gain of the oscillator is 0.309 MHz/mV with a control voltage from 0 V to 1.1 V. The circuit can work with a supply voltage as low as 1.2 V and the power consumption is only 0.46 mW at a 1.8 V supply voltage.
EDFA-based coupled opto-electronic oscillator and its phase noise
Salik, Ertan; Yu, Nan; Tu, Meirong; Maleki, Lute
2004-01-01
EDFA-based coupled opto-electronic oscillator (COEO), an integrated optical and microwave oscillator that can generate picosecond optical pulses, is presented. the phase noise measurements of COEO show better performance than synthesizer-driven mode-locked laser.
Influence of perturbative phase noise on active coherent polarization beam combining system.
Ma, Pengfei; Zhou, Pu; Wang, Xiaolin; Ma, Yanxing; Su, Rongtao; Liu, Zejin
2013-12-02
In this manuscript, the influence of perturbative phase noise on active coherent polarization beam combining (CPBC) system is studied theoretically and experimentally. By employing a photo-detector to obtain phase error signal for feedback loop, actively coherent polarization beam combining of two 20 W-level single mode polarization-maintained (PM) fiber amplifiers are demonstrated with more than 94% combining efficiency. Then the influence of perturbative phase noise on active CPBC system is illustrated by incorporating a simulated phase noise signal in one of the two amplifiers. Experimental results show that the combining efficiency of the CPBC system is susceptible to the frequency or amplitude of the perturbative phase noise. In order to ensure the combining efficiency of the unit of CPBC system higher than 90%, the competence of our active phase control module for high power operation is discussed, which suggests that it could be worked at 100s W power level. The relationship between residual phase noise of the active controller and the normalized voltage signal of the photo-detector is developed and validated experimentally. Experimental results correspond exactly with the theoretically analyzed combining efficiency. Our method offers a useful approach to estimate the influence of phase noise on CPBC system.
Oscillator Phase Noise: A Geometrical Approach
Djurhuus, Torsten; Krozer, Viktor; Vidkjær, Jens
2009-01-01
We construct a coordinate-independent description of oscillator linear response through a decomposition scheme derived independently of any Floquet theoretic results. Trading matrix algebra for a simpler graphical methodology, the text will present the reader with an opportunity to gain an intuit...... an intuitive understanding of the well-known phase noise macromodel. The topics discussed in this paper include the following: orthogonal decompositions, AM–PM conversion, and nonhyperbolic oscillator noise response....
Neutron residual stress measurements in linepipe
Law, Michael [ANTSO, PMB1 Menai, NSW, 2234 (Australia)]. E-mail: michael.law@ansto.gov.au; Gnaepel-Herold, Thomas [Department of Materials Science and Engineering, NCNR and University of Maryland (United States); Luzin, Vladimir [Department of Materials Science and Engineering, NCNR and University of Maryland (United States); Bowie, Graham [cNCNR and State University of New York at Stoneybrook (United States): Blue Scope Steel (Australia)
2006-11-15
Residual stresses in gas pipelines are generated by manufacturing and construction processes and may affect the subsequent pipe integrity. In the present work, the residual stresses in eight samples of linepipe were measured by neutron diffraction. Residual stresses changed with some coating processes. This has special implications in understanding and mitigating stress corrosion cracking, a major safety and economic problem in some gas pipelines.
Frequency and Phase Noise in Non-Linear Microwave Oscillator Circuits
Tannous, C.
2003-01-01
We have developed a new methodology and a time-domain software package for the estimation of the oscillation frequency and the phase noise spectrum of non-linear noisy microwave circuits based on the direct integration of the system of stochastic differential equations representing the circuit. Our theoretical evaluations can be used in order to make detailed comparisons with the experimental measurements of phase noise spectra in selected oscillating circuits.
Application of Machine Learning Techniques for Amplitude and Phase Noise Characterization
Zibar, Darko; de Carvalho, Luis Henrique Hecker; Piels, Molly
2015-01-01
In this paper, tools from machine learning community, such as Bayesian filtering and expectation maximization parameter estimation, are presented and employed for laser amplitude and phase noise characterization. We show that phase noise estimation based on Bayesian filtering outperforms...... conventional time-domain approach in the presence of moderate measurement noise. Additionally, carrier synchronization based on Bayesian filtering, in combination with expectation maximization, is demonstrated for the first time experimentally....
Very low-phase noise, coherent 94GHz radar for micro-Doppler and vibrometry studies
Robertson, Duncan A.; Brooker, Graham M.; Beasley, Patrick D. L.
2014-05-01
Micro-Doppler and vibrometry measurements require coherent radars with low phase noise. We report the development of a novel, very low phase noise 94 GHz radar, called T-220, which offers superior performance for micro-Doppler and vibrometry studies compared with our previous work. The radar uses a combination of direct digital synthesis (DDS) chirp generation, frequency upconversion and frequency multiplication to yield very low phase noise and rapid, contiguous chirps, necessary for Doppler studies and other coherent processing applications. Dual fan beam antennas are used to achieve negligible transmit-receive leakage, with fine azimuth resolution and modest elevation coverage. The resulting PPI imagery is very high fidelity with little or no evidence of phase noise effects.
Microwave Oscillator Phase Noise Requirement for TD-SCDMA Wireless Communication Systems
Song-Bai HE; Xiao-Huan Yan; Jing-Fu Bao
2007-01-01
In time division synchronous code division multiple access (TD-SCDMA) wireless communication systems, QPSK or 8PSK has been employed to support high data rate services and high efficiency in available bandwidth. The performance of such systems is affected by the phase noise of the microwave local oscillator. The phase noise model of synthesizer and the RF transceiver model for the phase noise effect are proposed for applications of TD-SCDMA systems. The relationship between the power spectral density (PSD) and root mean square (RMS) phase error is given. Then, the error vector magnitude (EVM) performance is analytically evaluated by using the single side band (SSB) phase noise. Theoretical results show agreement with those obtained by measurement data and therefore can be used to derive the TD-SCDMA system performance.
Optical Heterodyne With Lower Phase Noise
Logan, Ronald T.
1994-01-01
Proposed improvement enhances utility of optical-heterodyne apparatus used to generate radio signal at chosen frequency between 1 and 1,000 GHz. Two lasers injection-locked to third, mode-locked laser. Beat-frequency heterodyne output contains much less phase noise if generated from outputs of two independent lasers, and phase-coherent with reference signal. Potential applications include phased-array radar, fiber-optic communication systems, fiber-optic stabilized oscillators, and other applications involving conversions between optical and millimeter-wave signals.
Gierkink, S.L.J.; Wel, van der A.P.; Hoogzaad, G.; Klumperink, E.A.M.; Tuijl, van A.J.M.
1998-01-01
Spectrum measurement results of a CMOS ring oscillator are presented that show a 10 dB decrease in 1/f noise induced phase noise at a 2 dB increase in carrier power. Simple ring oscillator theory predicts that the 1/f noise induced phase noise is independent of carrier power. It is shown that an inc
Phase noise reduction of a semiconductor laser in a composite optical phase-locked loop
Satyan, Naresh; Sendowski, Jacob; Vasilyev, Arseny; Rakuljic, George; Yariv, Amnon
2010-12-01
The bandwidth and residual phase noise of optical phase-locked loops (OPLLs) using semiconductor lasers are typically constrained by the nonuniform frequency modulation response of the laser, limiting their usefulness in a number of applications. It is shown in this work that additional feedback control using an optical phase modulator improves the coherence between the master and slave lasers in the OPLL by achieving bandwidths determined only by the propagation delay in the loop. A phase noise reduction by more than a factor of two is demonstrated in a proof-of-concept experiment using a commercial distributed feedback semiconductor laser.
Watabe, Ken-ichi; Yanagimachi, Shinya; Ikegami, Takeshi; Iida, Hitoshi; Shimada, Yozo
2012-01-01
We have realized a phase noise standard of a signal with a -100 dBc/Hz flat phase noise at 10 MHz for Fourier frequencies of 1 Hz to 100 kHz, which ensures traceability to the International System of Units (SI). The flat phase noise signal is produced using a carrier combined with white noise. To ensure traceability, both the flat phase noise signal power and the power spectral density of white noise are determined with a calibrated power meter and the noise standard, respectively. The flatness of the phase noise standard is within ±0.7 dB.
François, B. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France); INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Calosso, C. E.; Micalizio, S. [INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Abdel Hafiz, M.; Boudot, R. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France)
2015-09-15
We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.
François, B; Calosso, C E; Abdel Hafiz, M; Micalizio, S; Boudot, R
2015-09-01
We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad(2)/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad(2)/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10(-14) for the Cs cell clock and 2 × 10(-14) for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10(-15) level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.
Speckle phase noise in coherent laser ranging: fundamental precision limitations.
Baumann, Esther; Deschênes, Jean-Daniel; Giorgetta, Fabrizio R; Swann, William C; Coddington, Ian; Newbury, Nathan R
2014-08-15
Frequency-modulated continuous-wave laser detection and ranging (FMCW LADAR) measures the range to a surface through coherent detection of the backscattered light from a frequency-swept laser source. The ultimate limit to the range precision of FMCW LADAR, or any coherent LADAR, to a diffusely scattering surface will be determined by the unavoidable speckle phase noise. Here, we demonstrate the two main manifestations of this limit. First, frequency-dependent speckle phase noise leads to a non-Gaussian range distribution having outliers that approach the system range resolution, regardless of the signal-to-noise ratio. These outliers are reduced only through improved range resolution (i.e., higher optical bandwidths). Second, if the range is measured during a continuous lateral scan across a surface, the spatial pattern of speckle phase is converted to frequency noise, which leads to additional excess range uncertainty. We explore these two effects and show that laboratory results agree with analytical expressions and numerical simulations. We also show that at 1 THz optical bandwidth, range precisions below 10 μm are achievable regardless of these effects.
Phase noise of self-sustained optomechanical oscillators
Fong, King Yan; Poot, Menno; Han, Xu; Tang, Hong X.
2014-01-01
In this paper we present a theory that predicts the phase noise characteristics of self-sustained optomechanical oscillators. By treating the cavity optomechanical system as a feedback loop consisting of an optical cavity and a mechanical resonator, we analytically derive the transfer functions relating the amplitude/phase noise of all the relevant dynamical quantities from the quantum Langevin equations, and obtain a closed-form expressions for the phase noise spectral densities contributed ...
A general theory of phase noise in electrical oscillators
Hajimiri, Ali; Lee, Thomas H.
1998-01-01
A general model is introduced which is capable of making accurate, quantitative predictions about the phase noise of different types of electrical oscillators by acknowledging the true periodically time-varying nature of all oscillators. This new approach also elucidates several previously unknown design criteria for reducing close-in phase noise by identifying the mechanisms by which intrinsic device noise and external noise sources contribute to the total phase noise. In particular, it expl...
Mohajerin-Ariaei, Amirhossein; Ziyadi, Morteza; Chitgarha, Mohammad Reza; Almaiman, Ahmed; Cao, Yinwen; Shamee, Bishara; Yang, Jeng-Yuan; Akasaka, Youichi; Sekiya, Motoyoshi; Takasaka, Shigehiro; Sugizaki, Ryuichi; Touch, Joseph D; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Willner, Alan E
2015-07-15
We demonstrate an all-optical phase noise mitigation scheme based on the generation, delay, and coherent summation of higher order signal harmonics. The signal, its third-order harmonic, and their corresponding delayed variant conjugates create a staircase phase-transfer function that quantizes the phase of quadrature-phase-shift-keying (QPSK) signal to mitigate phase noise. The signal and the harmonics are automatically phase-locked multiplexed, avoiding the need for phase-based feedback loop and injection locking to maintain coherency. The residual phase noise converts to amplitude noise in the quantizer stage, which is suppressed by parametric amplification in the saturation regime. Phase noise reduction of ∼40% and OSNR-gain of ∼3 dB at BER 10(-3) are experimentally demonstrated for 20- and 30-Gbaud QPSK input signals.
Frequency domain phase noise analysis of dual injection-locked optoelectronic oscillators.
Jahanbakht, Sajad
2016-10-01
Dual injection-locked optoelectronic oscillators (DIL-OEOs) have been introduced as a means to achieve very low-noise microwave oscillations while avoiding the large spurious peaks that occur in the phase noise of the conventional single-loop OEOs. In these systems, two OEOs are inter-injection locked to each other. The OEO with the longer optical fiber delay line is called the master OEO, and the other is called the slave OEO. Here, a frequency domain approach for simulating the phase noise spectrum of each of the OEOs in a DIL-OEO system and based on the conversion matrix approach is presented. The validity of the new approach is verified by comparing its results with previously published data in the literature. In the new approach, first, in each of the master or slave OEOs, the power spectral densities (PSDs) of two white and 1/f noise sources are optimized such that the resulting simulated phase noise of any of the master or slave OEOs in the free-running state matches the measured phase noise of that OEO. After that, the proposed approach is able to simulate the phase noise PSD of both OEOs at the injection-locked state. Because of the short run-time requirements, especially compared to previously proposed time domain approaches, the new approach is suitable for optimizing the power injection ratios (PIRs), and potentially other circuit parameters, in order to achieve good performance regarding the phase noise in each of the OEOs. Through various numerical simulations, the optimum PIRs for achieving good phase noise performance are presented and discussed; they are in agreement with the previously published results. This further verifies the applicability of the new approach. Moreover, some other interesting results regarding the spur levels are also presented.
Stimulated Brillouin scattering-induced phase noise in an interferometric fiber sensing system
Chen Wei; Meng Zhou; Zhou Hui-Juan; Luo Hong
2012-01-01
Stimulated Brillouin scattering-induced phase noise is harmful to interferometric fiber sensing systems. Thelocalized fluctuating model is used to study the intensity noise caused by the stimulated Brillouin scattering in a single-mode fiber.The phase noise structure is analyzed for an interferometric fiber sensing system,and an unbalanced Michelson interferometer with an optical path difference of 1 m,as well as the phase-generated carrier technique,is used to measure the phase noise.It is found that the phase noise is small when the input power is below the stimulated Brillouin scattering threshold,increases dramatically at first and then gradually becomes fiat when the input power is above the threshold,which is similar to the variation in relative intensity noise.It can be inferred that the increase in phase noise is mainly due to the broadening of the laser linewidth caused by stimulated Brillouin scattering,which is verified through linewidth measurements in the absence and presence of the stimulated Brillouin scattering.
Design of Residues Measurement Device of Uranium
SUI; Hong-zhi; XU; Zheng; LU; Wen-guang; HE; Li-xia; GAN; Lin
2012-01-01
<正>Nuclear materials will be deposited in the pipeline or various process equipment during the operation of nuclear facilities, such as dissolution reactor, because the recovery residue of uranium not dissolved, and a metal tubularis in the dissolution reactor cannot insert to the bottom of the container, so that part of the residual slag and the solution stored in the bottom of the reactor. When the equipment is used for treatment of nuclear material, it is difficult to put out all the nuclear material in the equipment. Therefore, measurement of these residues for nuclear material accountancy, the safe operation of the facilities,
Residual gravimetric method to measure nebulizer output.
Vecellio None, Laurent; Grimbert, Daniel; Bordenave, Joelle; Benoit, Guy; Furet, Yves; Fauroux, Brigitte; Boissinot, Eric; De Monte, Michele; Lemarié, Etienne; Diot, Patrice
2004-01-01
The aim of this study was to assess a residual gravimetric method based on weighing dry filters to measure the aerosol output of nebulizers. This residual gravimetric method was compared to assay methods based on spectrophotometric measurement of terbutaline (Bricanyl, Astra Zeneca, France), high-performance liquid chromatography (HPLC) measurement of tobramycin (Tobi, Chiron, U.S.A.), and electrochemical measurements of NaF (as defined by the European standard). Two breath-enhanced jet nebulizers, one standard jet nebulizer, and one ultrasonic nebulizer were tested. Output produced by the residual gravimetric method was calculated by weighing the filters both before and after aerosol collection and by filter drying corrected by the proportion of drug contained in total solute mass. Output produced by the electrochemical, spectrophotometric, and HPLC methods was determined after assaying the drug extraction filter. The results demonstrated a strong correlation between the residual gravimetric method (x axis) and assay methods (y axis) in terms of drug mass output (y = 1.00 x -0.02, r(2) = 0.99, n = 27). We conclude that a residual gravimetric method based on dry filters, when validated for a particular agent, is an accurate way of measuring aerosol output.
Turbo Receiver Design for Phase Noise Mitigation in OFDM Systems
Sridharan, Gokul
2010-01-01
This paper addresses the issue of phase noise in OFDM systems. Phase noise (PHN) is a transceiver impairment resulting from the non-idealities of the local oscillator. We present a case for designing a turbo receiver for systems corrupted by phase noise by taking a closer look at the effects of the common phase error (CPE). Using an approximate probabilistic framework called variational inference (VI), we develop a soft-in soft-out (SISO) algorithm that generates posterior bit-level soft estimates while taking into account the effect of phase noise. The algorithm also provides an estimate of the phase noise sequence. Using this SISO algorithm, a turbo receiver is designed by passing soft information between the SISO detector and an outer forward error correcting (FEC) decoder that uses a soft decoding algorithm. It is shown that the turbo receiver achieves close to optimal performance.
An X-Band low-power and low-phase-noise VCO using bondwire inductor
K. Hu
2009-05-01
Full Text Available In this paper a low-power low-phase-noise voltage-controlled-oscillator (VCO has been designed and, fabricated in 0.25 μm SiGe BiCMOS process. The resonator of the VCO is implemented with on-chip MIM capacitors and a single aluminum bondwire. A tail current filter is realized to suppress flicker noise up-conversion. The measured phase noise is −126.6 dBc/Hz at 1 MHz offset from a 7.8 GHz carrier. The figure of merit (FOM of the VCO is −192.5 dBc/Hz and the VCO core consumes 4 mA from a 3.3 V power supply. To the best of our knowledge, this is the best FOM and the lowest phase noise for bondwire VCOs in the X-band. This VCO will be used for satellite communications.
Zibar, Darko; Carvalho, L.; Piels, Molly
2014-01-01
We show that phase noise estimation based on Bayesian filtering outperforms conventional time-domain approaches in the presence of moderate measurement noise. Additionally, carrier synchronization based on Bayesian filtering, in combination with expectation maximization, is demonstrated...
A 20MHz Low Phase-Noise 0.35μm CMOS Crystal Oscillator
GENG Jian-qiang; LAN Jia-long
2005-01-01
The design procedure of a CMOS process integrating Colpitts cr(ystal oscillator is described in detail by using the tools of Matlab and advanced design system (ADS). The small-signal analysis is performed both in the viewpoint of negative resistance and positive feedback. The analysis of condition for reliable start-up of oscillation and design guides for low phase noise is introduced. The measured phase noise is (172dBc/Hz@10 kHz and the power dissipation is 0.36 mW at power supply 3V.
An X-Band low-power and low-phase-noise VCO using bondwire inductor
Hu, K.; F. Herzel; Scheytt, J. C.
2009-01-01
In this paper a low-power low-phase-noise voltage-controlled-oscillator (VCO) has been designed and, fabricated in 0.25 μm SiGe BiCMOS process. The resonator of the VCO is implemented with on-chip MIM capacitors and a single aluminum bondwire. A tail current filter is realized to suppress flicker noise up-conversion. The measured phase noise is −126.6 dBc/Hz at 1 MHz offset from a 7.8 GHz carrier. The figure of merit (FOM) of the VCO is −192.5 dBc/Hz and the VCO cor...
Spectral Weighting Functions for Single-symbol Phase-noise Specifications in OFDM Systems
Hoeksema, Fokke; Schiphorst, Roel; Slump, Kees
2003-01-01
For the specification of phase-noise requirements for the front-end of a HiperLAN/2 system we investigated available literature on the subject. Literature differed in several aspects. One aspect is in the type of phase-noise used (Wiener phase-noise or small-angle phase noise). A Wiener phase-noise
Measurement of post-void residual urine
Asimakopoulos, Anastasios D.; De Nunzio, Cosimo; Kocjancic, Ervin; Tubaro, Andrea; Rosier, Peter F.; Finazzi-Agrò, Enrico
2016-01-01
Aims To present the teaching module "Measurement of Post-void residual urine." Methods This module has been prepared by a Working Group of the ICS Urodynamics Committee. The methodology used included comprehensive literature review, consensus formation by the members of the Working Group, and review
Phase noise and jitter modeling for fractional-N PLLs
S. A. Osmany; Herzel, F.; Schmalz, K; Winkler, W.
2007-01-01
We present an analytical phase noise model for fractional-N phase-locked loops (PLL) with emphasis on integrated RF synthesizers in the GHz range. The noise of the crystal reference, the voltage-controlled oscillator (VCO), the loop filter, the charge pump, and the sigma-delta modulator (SDM) is filtered by the PLL operation. We express the rms phase error (jitter) in terms of phase noise of the reference, the VCO phase noise and the third-order loop filter parameters. In addition, we conside...
Effect of phase noise in an OFDM／OQAM system
ChenQifan; WuBingyang; ChengShixin
2003-01-01
The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation of OFDM/OQAM is first derived with the square root raised cosine (SRRC) filter as the pulse-shaping filter. Then the effect of multiplicative phase noise is equivalently represented as additive white Gaussian noise (AWGN), the variance of which is given analytically. We can observe that the same result as OFDM/QAM system is derived. Lastly, all the analytical results are verified by the bit error rate (BER) degradation through Monte Carlo simulation.
On the phase-noise and phase-error performances of multiphase LC CMOS VCOs
Andreani, Pietro; Wang, Xiaoyan
2004-01-01
This paper presents an analysis of phase noise in multiphase LC oscillators, and measurement results for several CMOS quadrature-voltage-controlled-oscillators (QVCOs) working in the 2-GHz frequency range. The phase noise data for a so-called BS-QVCO (- 140 dBc/Hz or less at 3 MHz frequency offset...... from the carrier, for a power consumption of 20.8 mW and a figure-of-merit of 184 dBc/Hz) show that phase noise performances are close to the previously derived limits. A systematic cause of departure from ideal quadrature between QVCO signals is also analyzed and measured experimentally, and a compact...... LC-tank layout that removes this source of phase error is proposed. A TS-QVCO designed with this technique shows a phase-noise figure-of-merit improvement of 4 dB, compared to a previous implementation. The measured equivalent phase error for all QVCOs is between 0.6degrees and 1degrees....
Phase noise and jitter modeling for fractional-N PLLs
S. A. Osmany
2007-06-01
Full Text Available We present an analytical phase noise model for fractional-N phase-locked loops (PLL with emphasis on integrated RF synthesizers in the GHz range. The noise of the crystal reference, the voltage-controlled oscillator (VCO, the loop filter, the charge pump, and the sigma-delta modulator (SDM is filtered by the PLL operation. We express the rms phase error (jitter in terms of phase noise of the reference, the VCO phase noise and the third-order loop filter parameters. In addition, we consider OFDM systems, where the PLL phase noise is reduced by digital signal processing after down-conversion of the RF signal to baseband. The rms phase error is discussed as a function of the loop parameters. Our model drastically simplifies the noise optimization of the PLL loop dynamics.
Phase noise and jitter modeling for fractional-N PLLs
Osmany, S. A.; Herzel, F.; Schmalz, K.; Winkler, W.
2007-06-01
We present an analytical phase noise model for fractional-N phase-locked loops (PLL) with emphasis on integrated RF synthesizers in the GHz range. The noise of the crystal reference, the voltage-controlled oscillator (VCO), the loop filter, the charge pump, and the sigma-delta modulator (SDM) is filtered by the PLL operation. We express the rms phase error (jitter) in terms of phase noise of the reference, the VCO phase noise and the third-order loop filter parameters. In addition, we consider OFDM systems, where the PLL phase noise is reduced by digital signal processing after down-conversion of the RF signal to baseband. The rms phase error is discussed as a function of the loop parameters. Our model drastically simplifies the noise optimization of the PLL loop dynamics.
Phase Noise of Optically Generated Microwave Using Sideband Injection Locking
HUANG Jin; SUN Chang-Zheng; SONG Yu; XIONG Bing; LUO Yi
2008-01-01
Optically generated 20-GHz microwave carriers with phase noise lower than -75 dBc/Hz at 10 kHz offset and lower than -90 dBc/Hz at 100 kHz offset are obtained using single- and double-sideband injection locking. Within the locking range, the effect of sideband injection locking can be regarded as narrow-band amplification of the modulation sidebands. Increasing the current of slave laser will increase the power of beat signal and reduce the phase noise to a certain extent. Double-sideband injection locking can increase the power of the generated microwave carrier while keeping the phase noise at a low level. It is also revealed that partially destruction of coherence between the two beating lights in the course of sideband injection locking would impair the phase noise performance.
Nonlinear phase noise in coherent optical OFDM transmission systems.
Zhu, Xianming; Kumar, Shiva
2010-03-29
We derive an analytical formula to estimate the variance of nonlinear phase noise caused by the interaction of amplified spontaneous emission (ASE) noise with fiber nonlinearity such as self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in coherent orthogonal frequency division multiplexing (OFDM) systems. The analytical results agree very well with numerical simulations, enabling the study of the nonlinear penalties in long-haul coherent OFDM systems without extensive numerical simulation. Our results show that the nonlinear phase noise induced by FWM is significantly larger than that induced by SPM and XPM, which is in contrast to traditional WDM systems where ASE-FWM interaction is negligible in quasi-linear systems. We also found that fiber chromatic dispersion can reduce the nonlinear phase noise. The variance of the total phase noise increases linearly with the bit rate, and does not depend significantly on the number of subcarriers for systems with moderate fiber chromatic dispersion.
Confidence estimates in simulation of phase noise or spectral density.
Ashby, Neil
2017-02-13
In this paper we apply the method of discrete simulation of power law noise, developed in [1],[3],[4], to the problem of simulating phase noise for a combination of power law noises. We derive analytic expressions for the probability of observing a value of phase noise L(f) or of any of the onesided spectral densities S(f); Sy(f), or Sx(f), for arbitrary superpositions of power law noise.
Advanced Phase noise modeling techniques of nonlinear microwave devices
Prigent, M.; J. C. Nallatamby; R. Quere
2004-01-01
In this paper we present a coherent set of tools allowing an accurate and predictive design of low phase noise oscillators. Advanced phase noise modelling techniques in non linear microwave devices must be supported by a proven combination of the following : - Electrical modeling of low-frequency noise of semiconductor devices, oriented to circuit CAD . The local noise sources will be either cyclostationary noise sources or quasistationary noise sources. - Theoretic...
Phase Noise Tolerant QPSK Receiver Using Phase Sensitive Wavelength Conversion
Da Ros, Francesco; Xu, Jing; Lei, Lei
2013-01-01
A novel QPSK receiver based on a phase noise reduction pre-stage exploiting PSA in a HNLF and balanced detection is presented. Receiver sensitivity improvement over a conventional balanced receiver is demonstrated.......A novel QPSK receiver based on a phase noise reduction pre-stage exploiting PSA in a HNLF and balanced detection is presented. Receiver sensitivity improvement over a conventional balanced receiver is demonstrated....
A low phase noise microwave source for atomic spin squeezing experiments in 87Rb
Chen, Zilong; Weiner, Joshua M; Thompson, James K; 10.1063/1.3700247
2012-01-01
We describe and characterize a simple, low cost, low phase noise microwave source that operates near 6.800 GHz for agile, coherent manipulation of ensembles of 87Rb. Low phase noise is achieved by directly multiplying a low phase noise 100 MHz crystal to 6.8 GHz using a non-linear transmission line and filtering the output with custom band-pass filters. The fixed frequency signal is single sideband modulated with a direct digital synthesis frequency source to provide the desired phase, amplitude, and frequency control. Before modulation, the source has a single sideband phase noise near -140 dBc/Hz in the range of 10 kHz to 1 MHz offset from the carrier frequency and -130 dBc/Hz after modulation. The resulting source is estimated to contribute added spin-noise variance 16 dB below the quantum projection noise level during quantum nondemolition measurements of the clock transition in an ensemble 7x10^5 87Rb atoms.
T. Musch
2003-01-01
Full Text Available The generation of analogue frequency ramps with non-fractional phase-locked-loops (PLL is a cost effective way of linearising varactor controlled oscillators (VCO. In case that the VCO shows a high phase-noise level, a single non-fractional PLL is not able to suppress the phase-noise of the VCO sufficiently. The reason for this is the limited loopbandwidth of the PLL. In the field of precise measurements a high phase-noise level is mostly not tolerable. Examples of VCO-types with an extremely high phase noise level are integrated millimetre wave oscillators based on GaAs-HEMT technology. Both, a low quality factor of the resonator and a high flicker-noise corner frequency of the transistors are the main reason for the poor phase-noise behaviour. On the other hand this oscillator type allows a cost effective implementation of a millimetre-wave VCO. Therefore, a cascaded two-loop structure is presented that is able to linearise a VCO and additionally to reduce its phase-noise significantly.
Kikuchi, Kazuro
2012-02-27
We develop a systematic method for characterizing semiconductor-laser phase noise, using a low-speed offline digital coherent receiver. The field spectrum, the FM-noise spectrum, and the phase-error variance measured with such a receiver can completely describe phase-noise characteristics of lasers under test. The sampling rate of the digital coherent receiver should be much higher than the phase-fluctuation speed. However, 1 GS/s is large enough for most of the single-mode semiconductor lasers. In addition to such phase-noise characterization, interpolating the taken data at 1.25 GS/s to form a data stream at 10 GS/s, we can predict the bit-error rate (BER) performance of multi-level modulated optical signals at 10 Gsymbol/s. The BER degradation due to the phase noise is well explained by the result of the phase-noise measurements.
Ultralow-phase-noise oscillators based on BAW resonators.
Li, Mingdong; Seok, Seonho; Rolland, Nathalie; Rolland, Paul; El Aabbaoui, Hassan; de Foucauld, Emeric; Vincent, Pierre; Giordano, Vincent
2014-06-01
This paper presents two 2.1-GHz low-phase noise oscillators based on BAW resonators. Both a single-ended common base structure and a differential Colpitts structure have been implemented in a 0.25-μm BiCMOS process. The detailed design methods including the realization, optimization, and test are reported. The differential Colpitts structure exhibits a phase noise 6.5 dB lower than the single-ended structure because of its good performance of power noise immunity. Comparison between the two structures is also carried out. The differential Colpitts structure shows a phase noise level of -87 dBc/Hz at 1-kHz offset frequency and a phase noise floor of -162 dBc/Hz, with an output power close to -6.5 dBm and a core consumption of 21.6 mW. Furthermore, with the proposed optimization methods, both proposed devices have achieved promising phase noise performance compared with state-of-the-art oscillators described in the literature. Finally, we briefly present the application of the proposed BAW oscillator to a micro-atomic clock.
Laser phase noise effects on the dynamics of optomechanical resonators
Phelps, Gregory A
2010-01-01
We investigate theoretically the influence of laser phase noise on the cooling and heating of a generic cavity optomechanical system. We derive the back-action damping and heating rates and the mechanical frequency shift of the radiation pressure-driven oscillating mirror, and derive the minimum phonon occupation number for small laser linewidths. We find that in practice laser phase noise does not pose serious limitations to ground state cooling. We then consider the effects of laser phase noise in a parametric cavity driving scheme that minimizes the back-action heating of one of the quadratures of the mechanical oscillator motion. Laser linewidths narrow compared to the decay rate of the cavity field will not pose any problems in an experimental setting, but broader linewidths limit the practicality of this back-action evasion method.
The minimization of ac phase noise in interferometric systems
Filinski, Ignacy; Gordon, R A
1994-01-01
A simple step-by-step procedure, including several novel techniques discussed in the Appendices, is given for minimizing ac phase noise in typical interferometric systems such as two-beam interferometers, holographic setups, four-wave mixers, etc. Special attention is given to index of refraction...... fluctuations, direct mechanical coupling, and acoustic coupling, whose importance in determining ac phase noise in interferometric systems has not been adequately treated. The minimization procedure must be carried out while continuously monitoring the phase noise which can be done very simply by using...... with the optical table will also have to be carefully carried out regardless of the type of interferometric system employed.It is recommended that this be followed by a simple, inexpensive change to a novel type of interferometer discussed in Appendix A which is inherently less sensitive to mechanical vibration...
Vibration induced phase noise in Mach-Zehnder atom interferometers
Miffre, A; Büchner, M; Trénec, G; Vigué, J; Miffre, Alain; Jacquey, Marion; B\\"{u}chner, Matthias; Vigu\\'{e}, Jacques
2006-01-01
The high inertial sensitivity of atom interferometers has been used to build accelerometers and gyrometers but this sensitivity makes these interferometers very sensitive to the laboratory seismic noise. This seismic noise induces a phase noise which is large enough to reduce the fringe visibility in many cases. We develop here a model calculation of this phase noise in the case of Mach-Zehnder atom interferometers and we apply this model to our thermal lithium interferometer. We are thus able to explain the observed dependence of the fringe visibility with the diffraction order. The dynamical model developed in the present paper should be very useful to further reduce this phase noise in atom interferometers and this reduction should open the way to improved interferometers.
Low bitrate system design in the presence of phase noise
Haugli, Hans-Christian
1995-01-01
There are a number of interesting mobile satellite applications that require the transmission of short packets of data. In the design of such systems one of the challenges is often to minimize the transmitted power to reduce cost, which implies using power efficient low bit-rate modulation and coding methods. PSK systems can be very power efficient, but at low bit-rates the carrier recovery circuits can be sensitive to oscillator phase noise. In this paper we address the problem of determining the lowest bit-rate that can be supported using PSK for a given level of system phase noise. The classical formulas are reviewed, and a method is derived to calculate the minimum C/N(sub 0) required to recover the carrier for CW, BPSK and QPSK signals for a given phase noise level.
Real Time Phase Noise Meter Based on a Digital Signal Processor
Angrisani, Leopoldo; D'Arco, Mauro; Greenhall, Charles A.; Schiano Lo Morille, Rosario
2006-01-01
A digital signal-processing meter for phase noise measurement on sinusoidal signals is dealt with. It enlists a special hardware architecture, made up of a core digital signal processor connected to a data acquisition board, and takes advantage of a quadrature demodulation-based measurement scheme, already proposed by the authors. Thanks to an efficient measurement process and an optimized implementation of its fundamental stages, the proposed meter succeeds in exploiting all hardware resources in such an effective way as to gain high performance and real-time operation. For input frequencies up to some hundreds of kilohertz, the meter is capable both of updating phase noise power spectrum while seamlessly capturing the analyzed signal into its memory, and granting as good frequency resolution as few units of hertz.
Simplified iterative algorithm for OFDM phase noise mitigation
Yang Jianhua; Zhao Danfeng; Yue Li; Zhao Chunhui
2007-01-01
OFDM has been widely adopted in several communication systems. However, OFDM systems are very sensitive to the phase noise, which causes the CPE (common phase error) and ICI (inter-carrier interference),and thus degrades the system performance significantly. Based on the IEEE 802.11a standard, a simplified iterative phase noise mitigation algorithm is proposed. The proposed algorithm has very low complexity, and requires no additional pilot information. The simulation result shows that good BER performance can be achieved through several few times of iteration.
Extra phase noise from thermal fluctuations in nonlinear optical crystals
César, J. E. S.; Coelho, A.S.; Cassemiro, K.N.
2009-01-01
We show theoretically and experimentally that scattered light by thermal phonons inside a second-order nonlinear crystal is the source of additional phase noise observed in optical parametric oscillators. This additional phase noise reduces the quantum correlations and has hitherto hindered the d...... the direct production of multipartite entanglement in a single nonlinear optical system. We cooled the nonlinear crystal and observed a reduction in the extra noise. Our treatment of this noise can be successfully applied to different systems in the literature....
Residual stress measurements in carbon steel
Heyman, J. S.; Min, N.
1986-01-01
External dc magnetic field-induced changes in natural velocity of Rayleigh surface waves were measured in steel specimens under various stress conditions. The low field slopes of curves representing the fractional changes of natural velocity were proved to provide correct stress information in steels with different metallurgical properties. The slopes of curves under uniaxial compression, exceeding about one third of the yield stress, fell below zero in all the specimens when magnetized along the stress axis. The slopes under tension varied among different steels but remained positive in any circumstances. The stress effect was observed for both applied and residual stress. A physical interpretation of these results is given based on the stress-induced domain structure changes and the delta epsilon effect. Most importantly, it is found that the influence of detailed metallurgical properties cause only secondary effects on the obtained stress information.
A low-phase-noise digitally controlled crystal oscillator for DVB TV tuners
Zhao Wei; Lu Lei; Tang Zhangwen, E-mail: zwtang@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)
2010-07-15
This paper presents a 25-MHz fully-integrated digitally controlled crystal oscillator (DCXO) with automatic amplitude control (AAC). The DCXO is based on Colpitts topology for one-pin solution. The AAC circuit is introduced to optimize the phase noise performance. The automatic frequency control is realized by a 10-bit thermometer-code segmental tapered MOS capacitor array, ensuring a {approx} 35 ppm tuning range and {approx} 0.04 ppm frequency step. The measured phase noise results are -139 dBc/Hz at 1 kHz and -151 dBc/Hz at 10 kHz frequency offset, respectively. The chip consumes 1 mA at 1.8V supply and occupies 0.4 mm{sup 2} in a 0.18-{mu}m CMOS process.
A low-phase-noise digitally controlled crystal oscillator for DVB TV tuners
Wei, Zhao; Lei, Lu; Zhangwen, Tang
2010-07-01
This paper presents a 25-MHz fully-integrated digitally controlled crystal oscillator (DCXO) with automatic amplitude control (AAC). The DCXO is based on Colpitts topology for one-pin solution. The AAC circuit is introduced to optimize the phase noise performance. The automatic frequency control is realized by a 10-bit thermometer-code segmental tapered MOS capacitor array, ensuring a ~ 35 ppm tuning range and ~ 0.04 ppm frequency step. The measured phase noise results are -139 dBc/Hz at 1 kHz and -151 dBc/Hz at 10 kHz frequency offset, respectively. The chip consumes 1 mA at 1.8V supply and occupies 0.4 mm2 in a 0.18-μm CMOS process.
Trade-off between phase-noise and signal quadrature in unilaterally coupled oscillators
Djurhuus, Torsten; Krozer, Viktor; Vidkjær, Jens
2005-01-01
We present a comprehensive nonlinear analysis of coupled oscillators and examine the trade-off between phase-noise of the oscillator and the quadrature precision. We show that asymmetry gives rise to amplitude and phase imbalance which are proportional to the inverse and inverse square......, respectively, of the relative coupling strength. It is shown that the level of AM-PM is determined by the nonlinearity of the coupling transconductance. The 3dB noise reduction in close-to-carrier phase-noise in quadrature oscillators due to mutual coupling is lost to the extra AM-PM noise for large coupling...... strengths. The additional contribution of the internal noise sources in the coupling circuit together with the AM-PM noise contribution explains why the 3dB noise reduction is rarely seen in measurements of this particular circuit....
Measurment Of Residual Stress In Ferromagnetic Materials
Namkung, Min; Yost, William T.; Kushnick, Peter W.; Grainger, John L.
1992-01-01
Magnetoacoustic (MAC) and magnetoacoustic emission (MAE) techniques combined to provide complete characterization of residual stresses in ferromagnetic structural materials. Combination of MAC and MAE techniques makes it possible to characterize residual tension and compression without being limited by surface conditions and unavailability of calibration standards. Significant in field of characterization of materials as well as detection of fatigue failure.
Measurment Of Residual Stress In Ferromagnetic Materials
Namkung, Min; Yost, William T.; Kushnick, Peter W.; Grainger, John L.
1992-01-01
Magnetoacoustic (MAC) and magnetoacoustic emission (MAE) techniques combined to provide complete characterization of residual stresses in ferromagnetic structural materials. Combination of MAC and MAE techniques makes it possible to characterize residual tension and compression without being limited by surface conditions and unavailability of calibration standards. Significant in field of characterization of materials as well as detection of fatigue failure.
Measurements of residual stress in fracture mechanics coupons
Prime, Michael B [Los Alamos National Laboratory; Hill, Michael R [U.C. DAVIS; Nav Dalen, John E [HILL ENGINEERING
2010-01-01
This paper describes measurements of residual stress in coupons used for fracture mechanics testing. The primary objective of the measurements is to quantify the distribution of residual stress acting to open (and/or close) the crack across the crack plane. The slitting method and the contour method are two destructive residual stress measurement methods particularly capable of addressing that objective, and these were applied to measure residual stress in a set of identically prepared compact tension (C(T)) coupons. Comparison of the results of the two measurement methods provides some useful observations. Results from fracture mechanics tests of residual stress bearing coupons and fracture analysis, based on linear superposition of applied and residual stresses, show consistent behavior of coupons having various levels of residual stress.
Phase noise reveals early category-specific modulation of the event-related potentials.
Németh, Kornél; Kovács, Petra; Vakli, Pál; Kovács, Gyula; Zimmer, Márta
2014-01-01
Previous studies have found that the amplitude of the early event-related potential (ERP) components evoked by faces, such as N170 and P2, changes systematically as a function of noise added to the stimuli. This change has been linked to an increased perceptual processing demand and to enhanced difficulty in perceptual decision making about faces. However, to date it has not yet been tested whether noise manipulation affects the neural correlates of decisions about face and non-face stimuli similarly. To this end, we measured the ERPs for faces and cars at three different phase noise levels. Subjects performed the same two-alternative age-discrimination task on stimuli chosen from young-old morphing continua that were created from faces as well as cars and were calibrated to lead to similar performances at each noise-level. Adding phase noise to the stimuli reduced performance and enhanced response latency for the two categories to the same extent. Parallel to that, phase noise reduced the amplitude and prolonged the latency of the face-specific N170 component. The amplitude of the P1 showed category-specific noise dependence: it was enhanced over the right hemisphere for cars and over the left hemisphere for faces as a result of adding phase noise to the stimuli, but remained stable across noise levels for cars over the left and for faces over the right hemisphere. Moreover, noise modulation altered the category-selectivity of the N170, while the P2 ERP component, typically associated with task decision difficulty, was larger for the more noisy stimuli regardless of stimulus category. Our results suggest that the category-specificity of noise-induced modulations of ERP responses starts at around 100 ms post-stimulus.
Design optimizations of phase noise, power consumption and frequency tuning for VCO
Nan, Chen; Shengxi, Diao; Lu, Huang; Xuefei, Bai; Fujiang, Lin
2013-09-01
To meet the requirements of the low power Zigbee system, VCO design optimizations of phase noise, power consumption and frequency tuning are discussed in this paper. Both flicker noise of tail bias transistors and up-conversion of flicker noise from cross-coupled pair are reduced by improved self-switched biasing technology, leading to low close-in phase noise. Low power is achieved by low supply voltage and triode region biasing. To linearly tune the frequency and get constant gain, distributed varactor structure is adopted. The proposed VCO is fabricated in SMIC 0.18-μm CMOS process. The measured linear tuning range is from 2.38 to 2.61 GHz. The oscillator exhibits low phase noise of -77.5 dBc/Hz and -122.8 dBc/Hz at 10 kHz and 1 MHz offset, respectively, at 2.55 GHz oscillation frequency while dissipating 2.7 mA from 1.2 V supply voltage, which well meet design specifications.
A low phase noise and low spur PLL frequency synthesizer for GNSS receivers
Sen, Li; Jinguang, Jiang; Xifeng, Zhou; Jianghua, Liu
2014-01-01
A low phase noise and low spur phase locked loop (PLL) frequency synthesizer for use in global navigation satellite system (GNSS) receivers is proposed. To get a low spur, the symmetrical structure of the phase frequency detector (PFD) produces four control signals, which can reach the charge pump (CP) simultaneously, and an improved CP is realized to minimize the charge sharing and the charge injection and make the current matched. Additionally, the delay is controllable owing to the programmable PFD, so the dead zone of the CP can be eliminated. The output frequency of the VCO can be adjusted continuously and precisely by using a programmable LC-TANK. The phase noise of the VCO is lowered by using appropriate MOS sizes. The proposed PLL frequency synthesizer is fabricated in a 0.18 μm mixed-signal CMOS process. The measured phase noise at 1 MHz offset from the center frequency is -127.65 dBc/Hz and the reference spur is -73.58 dBc.
Measurement of residual stresses using fracture mechanics weight functions
Fan, Y. [Bettis Atomic Power Laboratory, West Mifflin, PA (United States)
2001-07-01
A residual stress measurement method has been developed to quantify through-the-thickness residual stresses. Accurate measurement of residual stresses is crucial for many engineering structures. Fabrication processes such as welding and machining generate residual stresses that are difficult to predict. Residual stresses affect the integrity of structures through promoting failures due to brittle fracture, fatigue, stress corrosion cracking, and wear. In this work, the weight function theory of fracture mechanics is used to measure residual stresses. The weight function theory is an important development in computational fracture mechanics. Stress intensity factors for arbitrary stress distribution on the crack faces can be accurately and efficiently computed for predicting crack growth. This paper demonstrates that the weight functions are equally useful in measuring residual stresses. In this method, an artificial crack is created by a thin cut in a structure containing residual stresses. The cut relieves the residual stresses normal to the crack-face and allows the relieved residual stresses to deform the structure. Strain gages placed adjacent to the cut measure the relieved strains corresponding to incrementally increasing depths of the cut. The weight functions of the cracked body relate the measured strains to the residual stresses normal to the cut within the structure. The procedure details, such as numerical integration of the singular functions in applying the weight function method, will be discussed. (author)
VARIANCE OF NONLINEAR PHASE NOISE IN FIBER-OPTIC SYSTEM
RANJU KANWAR; SAMEKSHA BHASKAR
2013-01-01
In communication system, the noise process must be known, in order to compute the system performance. The nonlinear effects act as strong perturbation in long- haul system. This perturbation effects the signal, when interact with amplitude noise, and results in random motion of the phase of the signal. Based on the perturbation theory, the variance of nonlinear phase noise contaminated by both self- and cross-phase modulation, is derived analytically for phase-shift- keying system. Through th...
Model of flicker noise effects on phase noise in oscillators
Centurelli, Francesco; Ercolani, Alessandro; Tommasino, Pasquale; Trifiletti, Alessandro
2003-05-01
Phase noise models that describe the near-carrier spectrum in an accurate but insightful way are needed, to better optimize the oscillator design. In this paper we present a model to describe the effect of flicker noise sources on the phase noise of an oscillator, that can be applied both to linear oscillators and to nonlinear structures like relaxation and ring oscillators, so extending previous works that considered only the effect of the flicker noise superimposed to the control voltage of a VCO. In the phase noise of an oscillator we can separate the effect of high frequency noise sources, that can be described by a short-time-constant system, and the effect of low frequency noises (mostly flicker sources), described by a system with time constants much slower than the oscillation period. Flicker noise has been considered to cause a change in the circuit bias point; this bias point change can be mapped in a shift of the oscillation frequency by exploiting Barkhausen conditions (for linear oscillators) or obtaining this link by simulations. The power spectral density of the oscillator can then be obtained as the probability distribution of the oscillation frequency, starting from the flicker noise probability distribution. If the effect of high frequency noise sources is also taken into account, the overall oscillator spectrum can be obtained as a convolution of the spectrum due to flicker sources with the Lorentzian-shaped spectrum due to white noise sources, in analogy with the description of inhomogeneous broadening of laser linewidth.
VARIANCE OF NONLINEAR PHASE NOISE IN FIBER-OPTIC SYSTEM
RANJU KANWAR
2013-04-01
Full Text Available In communication system, the noise process must be known, in order to compute the system performance. The nonlinear effects act as strong perturbation in long- haul system. This perturbation effects the signal, when interact with amplitude noise, and results in random motion of the phase of the signal. Based on the perturbation theory, the variance of nonlinear phase noise contaminated by both self- and cross-phase modulation, is derived analytically for phase-shift- keying system. Through this work, it is investigated that for longer transmission distance, 40-Gb/s systems are more sensitive to nonlinear phase noise as compared to 50-Gb/s systems. Also, when transmitting the data through the fiber optic link, bit errors are produced due to various effects such as noise from optical amplifiers and nonlinearity occurring in fiber. On the basis of the simulation results , we have compared the bit error rate based on 8-PSK with theoretical results, and result shows that in real time approach, the bit error rate is high for the same signal to noise ratio. MATLAB software is used to validate the analytical expressions for the variance of nonlinear phase noise.
Design & Implementation of High Switching & Low Phase Noise Frequency Synthesizer
Ali M. N. Hassan
2006-01-01
Full Text Available This research describes the design & implementation of frequency synthesizer using single loop Phase lock loop with the following specifications: Frequency range (1.5 2.75 GHz,Step size (1 MHz, Switching time 36.4 µs, & phase noise @10 kHz = -92dBc & spurious -100 dBc The development in I.C. technology provide the simplicity in the design of frequency synthesizer because it implements the phase frequency detector(PFD , prescalar & reference divider in single chip. Therefore our system consists of a single chip contains (low phase noise PFD, charge pump, prescalar & reference divider, voltage controlled oscillator , loop filter & reference oscillator. The single chip is used to provide the following properties :Low power consumptionSmall size, light weight.Flexibility in selecting crystal oscillator frequencies to fit into the system frequency planning.High reliability.The application of this synthesizer in frequency hopping systems, satellite communications & radar because it has high switching speed ,low phase noise & low spurious level.
Implementation of a Cross-Spectrum FFT Analyzer for a Phase-Noise Test System in a Low-Cost FPGA
Patrick Fleischmann
2015-01-01
Full Text Available The cross-correlation method allows phase-noise measurements of high-quality devices with very low noise levels, using reference sources with higher noise levels than the device under test. To implement this method, a phase-noise analyzer needs to compute the cross-spectral density, that is, the Fourier transform of the cross-correlation, of two time series over a wide frequency range, from fractions of Hz to tens of MHz. Furthermore, the analyzer requires a high dynamic range to accommodate the phase noise of high-quality oscillators that may fall off by more than 100 dB from close-in noise to the noise floor at large frequency offsets. This paper describes the efficient implementation of a cross-spectrum analyzer in a low-cost FPGA, as part of a modern phase-noise analyzer with very fast measurement time.
Residual limb volume change: Systematic review of measurement and management
Joan E. Sanders, PhD
2011-10-01
Full Text Available Management of residual limb volume affects decisions regarding timing of fit of the first prosthesis, when a new prosthetic socket is needed, design of a prosthetic socket, and prescription of accommodation strategies for daily volume fluctuations. This systematic review assesses what is known about measurement and management of residual limb volume change in persons with lower-limb amputation. Publications that met inclusion criteria were grouped into three categories: group I: descriptions of residual limb volume measurement techniques; group II: studies investigating the effect of residual limb volume change on clinical care in people with lower-limb amputation; and group III: studies of residual limb volume management techniques or descriptions of techniques for accommodating or controlling residual limb volume. We found that many techniques for the measurement of residual limb volume have been described but clinical use is limited largely because current techniques lack adequate resolution and in-socket measurement capability. Overall, limited evidence exists regarding the management of residual limb volume, and the evidence available focuses primarily on adults with transtibial amputation in the early postoperative phase. While we can draw some insights from the available research about residual limb volume measurement and management, further research is required.
The new method for the residual gas density measurements
Anashin, V V; Krasnov, A A; Malyshev, O B; Nas'mov, V P; Pyata, E I; Shaftan, T V
2001-01-01
A new method of measurement for residual gas density in the vacuum chambers in presence of synchrotron radiation (SR) is described. The method is based on using a photomultiplier tube for the detection of the SR-stimulated residual gas luminescence, which is proportional to the residual gas density and SR intensity. The design of the experimental setup and results of the measurements of densities of residual gases (H sub 2 , CO sub 2 , CO, N sub 2 , Ar and O sub 2) are submitted.
Numerical generation of laser-resonance phase noise for optical communication simulators.
Ó Dúill, Seán P; Anthur, Aravind P; Huynh, Tam N; Naimi, Sepideh T; Nguyen, Lim; Venkitesh, Deepa; Barry, Liam P
2015-04-10
We generate random numerical waveforms that mimic laser phase noise incorporating laser-resonance enhanced phase noise. The phase noise waveforms are employed in system simulators to estimate the resulting bit error rate penalties for differential quadrature phase shift keying signals. The results show that baudrate dependence of the bit error rate performance arises from laser-resonance phase noise. In addition, we show with supporting experimental results that the laser-resonance phase noise on the pumps in four-wave-mixing-based wavelength converters is responsible for large bit error rate floors.
Yeh, Yen-Liang; Chang, Hong-Yeh
2014-12-01
In this paper, we present design and analysis of a K-band (18 to 26.5 GHz) low-phase-noise phase-locked loop (PLL) with the subharmonically injection-locked (SIL) technique. The phase noise of the PLL with subharmonic injection is investigated, and a modified phase noise model of the PLL with SIL technique is proposed. The theoretical calculations agree with the experimental results. Moreover, the phase noise of the PLL can be improved with the subharmonic injection. To achieve K-band operation with low dc power consumption, a divide-by-3 injection-locked frequency divider (ILFD) is used as a frequency prescaler. The measured phase noise of the PLL without injection is -110 dBc/Hz at 1 MHz offset at the operation frequency of 23.08 GHz. With the subharmonic injection, the measured phase noises at 1 MHz offset are -127, -127, and -119 dBc/Hz for the subharmonic injection number NINJ = 2, 3, and 4, respectively. Moreover, the performance of the proposed PLL with and without SIL technique can be compared with the reported advanced CMOS PLLs.
Residual stress measurement in silicon sheet by shadow moire interferometry
Kwon, Y.; Danyluk, S.; Bucciarelli, L.; Kalejs, J. P.
1987-01-01
A shadow moire interferometry technique has been developed to measure residual strain in thin silicon sheet. The curvature of a segment of sheet undergoing four-point bending is analyzed to include the applied bending moments, the in-plane residual stresses, and the 'end effect' of the sheet since it is of finite length. The technique is applied to obtain residual stress distributions for silicon sheet grown by the edge-defined film-fed growth technique.
On the investigation of voltage controlled oscillator phase noise for IoT applications
Haddad F.
2016-01-01
Full Text Available Voltage controlled oscillator (VCO is one of the key elements in radio frequency (RF transceivers. A VCO working at 2.4 GHz and designed in CMOS technology is presented. It is suitable for low-cost and low-noise applications using wireless standards such as ZigBee, Bluetooth, Wi-Fi and WPAN (Wireless Personal Area Network. The noise characteristics of this RF VCO are investigated. Noise measurements, especially, phase noise are achieved under different environmental conditions.
A low-phase-noise wide-band CMOS quadrature VCO for multi-standard RF front-ends
Fard, Ali; Andreani, Pietro
2005-01-01
A low phase noise CMOS LC quadrature VCO (QVCO) with a wide frequency range of 3.6-5.6 GHz, designed in a standard 0.18 μm process for multi-standard front-ends, is presented. A significant advantage of the topology is the larger oscillation amplitude when compared to other conventional QVCO...... structures. The QVCO is compared to a double cross-coupled LC-tank differential oscillator, both in theory and experiments, for evaluation of its phase noise, providing a good insight into its performance. The measured data displays up to 2 dBc/Hz lower phase noise in the 1/f2 region for the QVCO, when...... consuming twice the current of the differential VCO, based on an identical LC-tank. Experimental results on the QVCO show a phase noise level of -127.5 dBc/Hz at 3 MHz offset from a 5.6 GHz carrier while dissipating 8 mA of current, resulting in a figure of merit of 181.3 dBc/Hz....
Pan Yaohua; Mei Niansong; Chen Hu; Huang Yumei; Hong Zhiliang
2012-01-01
A low-phase-noise ∑-△ fractional-N frequency synthesizer for GSM/PCS/DCS/WCDMA transceivers is presented.The voltage controlled oscillator is designed with a modified digital controlled capacitor array to extend the tuning range and minimize phase noise.A high-resolution adaptive frequency calibration technique is introduced to automatically choose frequency bands and increase phase-noise immunity.A prototype is implemented in 0.13 μm CMOS technology.The experimental results show that the designed 1.2 V wideband frequency synthesizer is locked from 3.05 to 5.17 GHz within 30μs,which covers all five required frequency bands.The measured in-band phase noise are -89,-95.5 and -101 dBc/Hz for 3.8 GHz,2 GHz and 948 MHz carriers,respectively,and accordingly the out-of-band phase noise are -121,-123 and -132 dBc/Hz at 1 MHz offset,which meet the phase-noise-mask requirements of the above-mentioned standards.
SEMICONDUCTOR INTEGRATED CIRCUITS: A 0.8 V low power low phase-noise PLL
Yan, Han; Xiao, Liang; Haifeng, Zhou; Yinfang, Xie; Waisum, Wong
2010-08-01
A low power and low phase noise phase-locked loop (PLL) design for low voltage (0.8 V) applications is presented. The voltage controlled oscillator (VCO) operates from a 0.5 V voltage supply, while the other blocks operate from a 0.8 V supply. A differential NMOS-only topology is adopted for the oscillator, a modified precharge topology is applied in the phase-frequency detector (PFD), and a new feedback structure is utilized in the charge pump (CP) for ultra-low voltage applications. The divider adopts the extended true single phase clock DFF in order to operate in the high frequency region and save circuit area and power. In addition, several novel design techniques, such as removing the tail current source, are demonstrated to cut down the phase noise. Implemented in the SMIC 0.13 μm RF CMOS process and operated at 0.8 V supply voltage, the PLL measures a phase noise of-112.4 dBc/Hz at an offset frequency of 1 MHz from the carrier and a frequency range of 3.166-3.383 GHz. The improved PFD and the novel CP dissipate 0.39 mW power from a 0.8 V supply. The occupied chip area of the PFD and CP is 100 × 100 μm2. The chip occupies 0.63 mm2, and draws less than 6.54 mW from a 0.8 V supply.
An analytical formulation for phase noise in MEMS oscillators.
Agrawal, Deepak; Seshia, Ashwin
2014-12-01
In recent years, there has been much interest in the design of low-noise MEMS oscillators. This paper presents a new analytical formulation for noise in a MEMS oscillator encompassing essential resonator and amplifier nonlinearities. The analytical expression for oscillator noise is derived by solving a second-order nonlinear stochastic differential equation. This approach is applied to noise modeling of an electrostatically addressed MEMS resonator-based square-wave oscillator in which the resonator and oscillator circuit nonlinearities are integrated into a single modeling framework. By considering the resulting amplitude and phase relations, we derive additional noise terms resulting from resonator nonlinearities. The phase diffusion of an oscillator is studied and the phase diffusion coefficient is proposed as a metric for noise optimization. The proposed nonlinear phase noise model provides analytical insight into the underlying physics and a pathway toward the design optimization for low-noise MEMS oscillators.
A 2.3GHz LC-tank CMOS VCO with optimal phase noise performance
Andreani, Pietro; Fard, Ali
2006-01-01
The phase-noise theory and design of a differential CMOS LC-tank VCO with double switch pair is presented. A formula for the minimum achievable phase noise in the 1/f2 region is derived. The 2.15 to 2.35GHz 0.3mum CMOS VCO has a phase noise of -143.9dBc/Hz at 3MHz offset and draws 4mA from a 2.5V...
Contribution of off-resonant states to the phase noise of quantum dot lasers.
Wang, Cheng; Zhuang, Jun-Ping; Grillot, Frédéric; Chan, Sze-Chun
2016-12-26
The phase noise of quantum dot lasers is investigated theoretically by coupling the Langevin noise sources into the rate equations. The off-resonant populations in the excited state and in the carrier reservoir contribute to the phase noise of ground-state emission lasers through the phase-amplitude coupling effect. This effect arises from the optical-noise induced carrier fluctuations in the off-resonant states. In addition, the phase noise has low sensitivity to the carrier scattering rates.
Multiple Hypotheses Iterative Decoding of LDPC in the Presence of Strong Phase Noise
Shayovitz, Shachar; Raphaeli, Dan
2012-01-01
Many satellite communication systems operating today employ low cost upconverters or downconverters which create phase noise. This noise can severely limit the information rate of the system and pose a serious challenge for the detection systems. Moreover, simple solutions for phase noise tracking such as PLL either require low phase noise or otherwise require many pilot symbols which reduce the effective data rate. In the last decade we have witnessed a significant amount of research done on...
Ultrasonic measurement of residual stress in shot peened aluminum alloy
Lavrentyev, Anton I.; Veronesi, William A.
2001-04-01
Shot peening is a well-known method for extending the fatigue life of metal components by introducing compressive residual stresses near their surfaces. The capability to non-destructively evaluate the near surface residual stress would greatly aid the assurance of proper fatigue life in shot-peened components. This paper addresses issues encountered in near-surface residual stress measurement by an ultrasonic surface wave method. In this method, a variation of ultrasonic surface wave speed with shot peening intensity is measured. Since the effective wave penetration depth inversely related to the excitation frequency, by making measurements at different frequencies, the method has the potential to provide the stress-depth profile. Experiments were conducted on aluminum specimens (alloy 7075-T7351) peened within the Almen peening intensity from 4A-16A. Several factors were found to contribute to the measured responses: surface roughness, near surface texture change, dislocation density increase and residual stress. In this paper, the contributions of residual stress, dislocation density and surface roughness to the overall effect are separately estimated. It is shown that the experimentally observed velocity change in shot peened samples is dominated by the effect of surface roughness while the role of residual stress is much smaller.
A Low Phase Noise Fully Monolithic 6 GHz Differential Coupled NMOS LC-VCO
Moalla, Dorra Mellouli; Cordeau, David; Mnif, Hassene; Paillot, Jean-Marie; Loulou, Mourad
2016-01-01
A fully monolithic 6 GHz low-phase noise Voltage-Controlled-Oscillator (VCO) is presented in this paper. It consists in two LC-NMOS differential VCOs coupled through a resistive network and is implemented on a 0.25 µm BiCMOS SiGe process. This proposed integrated VCO can be used also for phased-array applications to steer the beam over the entire spatial range. In this case, the radiation pattern of the phased antenna array is steered in a particular direction by establishing a constant phase progression in the oscillator chain which can be obtained by detuning the free-running frequencies of the two oscillators in the array. At 2.5 V power supply voltage and a power dissipation of 62.5 mW, the coupled VCO array features a measured worst case phase noise of -102.4 dBc/Hz and -125.64 dBc/Hz at 100 kHz and 1 MHz frequency offset respectively from a 6 GHz carrier. The tuning range is about 400 MHz, from 5.85 to 6.25 GHz, for a tuning voltage varying from 0 to 2.5 V.
Intensity and phase noise correlations in a dual-frequency VECSEL operating at telecom wavelength
De, Syamsundar; Bouchoule, Sophie; Alouini, Mehdi; Bretenaker, Fabien
2015-01-01
The amplitude and phase noises of a dual-frequency vertical-external-cavity surface-emitting laser (DF-VECSEL) operating at telecom wavelength are theoretically and experimentally investigated in detail. In particular, the spectral behavior of the correlation between the intensity noises of the two modes of the DF-VECSEL is measured. Moreover, the correlation between the phase noise of the radio-frequency (RF) beatnote generated by optical mixing of the two laser modes with the intensity noises of the two modes is investigated. All these spectral behaviors of noise correlations are analyzed for two different values of the nonlinear coupling between the laser modes. We find that to describe the spectral behavior of noise correlations between the laser modes, it is of utmost importance to have a precise knowledge about the spectral behavior of the pump noise, which is the dominant source of noise in the frequency range of our interest (10 kHz to 35 MHz). Moreover, it is found that the noise correlation also dep...
Jia, Yanbing; Gu, Huaguang
2015-12-01
The effect of phase noise on the coherence dynamics of a neuronal network composed of FitzHugh-Nagumo (FHN) neurons is investigated. Phase noise can induce dissimilar coherence resonance (CR) effects for different coupling strength regimes. When the coupling strength is small, phase noise can induce double CRs. One corresponds to the average frequency of phase noise, and the other corresponds to the intrinsic firing frequency of the FHN neuron. When the coupling strength is large enough, phase noise can only induce single CR, and the CR corresponds to the intrinsic firing frequency of the FHN neuron. The results show a transition from double CRs to single CR with the increase in the coupling strength. The transition can be well interpreted based on the dynamics of a single neuron stimulated by both phase noise and the coupling current. When the coupling strength is small, the coupling current is weak, and phase noise mainly determines the dynamics of the neuron. Moreover, the phase-noise-induced double CRs in the neuronal network are similar to the phase-noise-induced double CRs in an isolated FHN neuron. When the coupling strength is large enough, the coupling current is strong and plays a key role in the occurrence of the single CR in the network. The results provide a novel phenomenon and may have important implications in understanding the dynamics of neuronal networks.
Thermo-elastic induced phase noise in the LISA Pathfinder spacecraft
Gibert, F.; Nofrarias, M.; Karnesis, N.; Gesa, L.; Martín, V.; Mateos, I.; Lobo, A.; Flatscher, R.; Gerardi, D.; Burkhardt, J.; Gerndt, R.; Robertson, D. I.; Ward, H.; McNamara, P. W.; Guzmán, F.; Hewitson, M.; Diepholz, I.; Reiche, J.; Heinzel, G.; Danzmann, K.
2015-02-01
During the on-station thermal test campaign of the LISA Pathfinder, the diagnostics subsystem was tested in nearly space conditions for the first time after integration in the satellite. The results showed the compliance of the temperature measurement system, obtaining temperature noise around {{10}-4} K H{{z}-1/2} in the frequency band 1-30 mHz. In addition, controlled injection of heat signals to the suspension struts anchoring the LISA Technology Package (LTP) core assembly to the satellite structure allowed us to experimentally estimate, for the first time, the phase noise contribution through thermo-elastic distortion of the LTP interferometer, the satellite's main instrument. Such contribution was found to be at {{10}-12} mH{{z}-1/2}, a factor of 30 below the measured noise at the lower end of the measurement bandwidth (1 mHz).
Thermo-elastic induced phase noise in the LISA Pathfinder spacecraft
Gibert, Ferran; Karnesis, Nikolaos; Gesa, Lluís; Martín, Víctor; Mateos, Ignacio; Lobo, Alberto; Flatscher, Reinhold; Gerardi, Domenico; Burkhardt, Johannes; Guzmán, Felipe; Heinzel, Gerhard; Danzmann, Karsten
2014-01-01
During the On-Station Thermal Test campaign of the LISA Pathfinder the data and diagnostics subsystem was tested in nearly space conditions for the first time after integration in the satellite. The results showed the compliance of the temperature measurement system, obtaining temperature noise around $10^{-4}\\,{\\rm K}\\, {\\rm Hz}^{-1/2}$ in the frequency band of $1-30\\;{\\rm mHz}$. In addition, controlled injection of heat signals to the suspension struts anchoring the LISA Technology Package (LTP) Core Assembly to the satellite structure allowed to experimentally estimate for the first time the phase noise contribution through thermo-elastic distortion of the LTP interferometer, the satellite's main instrument. Such contribution was found to be at $10^{-12}\\,{\\rm m}\\, {\\rm Hz}^{-1/2}$, a factor of 30 below the measured noise at the lower end of the measurement bandwidth ($1\\,{\\rm mHz}$).
New methods to measure residues coevolution in proteins
Dou Yongchao
2011-05-01
Full Text Available Abstract Background The covariation of two sites in a protein is often used as the degree of their coevolution. To quantify the covariation many methods have been developed and most of them are based on residues position-specific frequencies by using the mutual information (MI model. Results In the paper, we proposed several new measures to incorporate new biological constraints in quantifying the covariation. The first measure is the mutual information with the amino acid background distribution (MIB, which incorporates the amino acid background distribution into the marginal distribution of the MI model. The modification is made to remove the effect of amino acid evolutionary pressure in measuring covariation. The second measure is the mutual information of residues physicochemical properties (MIP, which is used to measure the covariation of physicochemical properties of two sites. The third measure called MIBP is proposed by applying residues physicochemical properties into the MIB model. Moreover, scores of our new measures are applied to a robust indicator conn(k in finding the covariation signal of each site. Conclusions We find that incorporating amino acid background distribution is effective in removing the effect of evolutionary pressure of amino acids. Thus the MIB measure describes more biological background information for the coevolution of residues. Besides, our analysis also reveals that the covariation of physicochemical properties is a new aspect of coevolution information.
A low-phase-noise ring oscillator with coarse and fine tuning in a standard CMOS process
Haijun, Gao; Lingling, Sun; Xiaofei, Kuang; Liheng, Lou
2012-07-01
A low-phase-noise wideband ring oscillator with coarse and fine tuning techniques implemented in a standard 65 nm CMOS process is presented. Direct frequency modulation in the ring oscillator is analyzed and a switched capacitor array is introduced to produce the lower VCO gain required to suppress this effect. A two-dimensional high-density stacked MOM-capacitor was adopted as the switched capacitor to make the proposed ring VCO compatible with standard CMOS processes. The designed ring VCO exhibits an output frequency from 480 to 1100 MHz, resulting in a tuning range of 78%, and the measured phase noise is -120 dBc/Hz @ 1 MHz at 495 MHz output. The VCO core consumes 3.84 mW under a 1.2 V supply voltage and the corresponding FOM is -169 dBc/Hz.
A 6 GHz high power and low phase noise VCO using an InGaP/GaAs HBT
王显泰; 申华军; 金智; 陈延湖; 刘新宇
2009-01-01
A 6 GHz voltage controlled oscillator (VCO) optimized for power and noise performance was designed and characterized. This VCO was designed with the negative-resistance (Neg-R) method, utilizing an InGaP/GaAs hetero-junction bipolar transistor in the negative-resistance block. A proper output matching network and a high Q stripe line resonator were used to enhance output power and depress phase noise. Measured central frequency of the VCO was 6.008 GHz. The tuning range was more than 200 MHz. At the central frequency, an output power of 9.8 dBm and phase noise of -122.33 dBc/Hz at 1 MHz offset were achieved, the calculated RF to DC efficiency was about 14%, and the figure of merit was -179.2 dBc/Hz.
A Ka-band monolithic low phase noise coplanar waveguide oscillator using InAlAs/InGaAs HBT
Cui, Delong; Hsu, Shawn; Pavlidis, Dimitris; Chin, Patrick; Block, Tom
2002-02-01
A Ka-band oscillator has been designed, fabricated and tested using InAlAs/InGaAs HBTs. Coplanar waveguide technology has been employed to improve the Q-factor of the circuit. An output power of 2.6 dBm with DC to RF conversion efficiency of 7.8% was measured at 31.7 GHz. Low phase noise of -87 and -112 dBc/Hz were achieved at an offset frequency of 100 kHz and 1 MHz respectively. These low phase noise values can be attributed to the low 1/ f noise of the InAlAs/InGaAs HBT devices and the coplanar design used for the circuit.
Residual Stress Determination from a Laser-Based Curvature Measurement
Swank, William David; Gavalya, Rick Allen; Wright, Julie Knibloe; Wright, Richard Neil
2000-05-01
Thermally sprayed coating characteristics and mechanical properties are in part a result of the residual stress developed during the fabrication process. The total stress state in a coating/substrate is comprised of the quench stress and the coefficient of thermal expansion (CTE) mismatch stress. The quench stress is developed when molten particles impact the substrate and rapidly cool and solidify. The CTE mismatch stress results from a large difference in the thermal expansion coefficients of the coating and substrate material. It comes into effect when the substrate/coating combination cools from the equilibrated deposit temperature to room temperature. This paper describes a laser-based technique for measuring the curvature of a coated substrate and the analysis required to determine residual stress from curvature measurements. Quench stresses were determined by heating the specimen back to the deposit temperature thus removing the CTE mismatch stress. By subtracting the quench stress from the total residual stress at room temperature, the CTE mismatch stress was estimated. Residual stress measurements for thick (>1mm) spinel coatings with a Ni-Al bond coat on 304 stainless steel substrates were made. It was determined that a significant portion of the residual stress results from the quenching stress of the bond coat and that the spinel coating produces a larger CTE mismatch stress than quench stress.
Measuring depth profiles of residual stress with Raman spectroscopy
Enloe, W.S.; Sparks, R.G.; Paesler, M.A.
1988-12-01
Knowledge of the variation of residual stress is a very important factor in understanding the properties of machined surfaces. The nature of the residual stress can determine a part`s susceptibility to wear deformation, and cracking. Raman spectroscopy is known to be a very useful technique for measuring residual stress in many materials. These measurements are routinely made with a lateral resolution of 1{mu}m and an accuracy of 0.1 kbar. The variation of stress with depth; however, has not received much attention in the past. A novel technique has been developed that allows quantitative measurement of the variation of the residual stress with depth with an accuracy of 10nm in the z direction. Qualitative techniques for determining whether the stress is varying with depth are presented. It is also demonstrated that when the stress is changing over the volume sampled, errors can be introduced if the variation of the stress with depth is ignored. Computer aided data analysis is used to determine the depth dependence of the residual stress.
Phase noise approximation analysis for the OFDM system
无
2007-01-01
The influence of phase noise (PN) present at the access point (AP) and mobile terminator (MT) may degrade the performance in orthogonal frequency division multiplexing (OFDM) system, because the OFDM system is sensitive to the PN.The method of PN approximation based on the PN power spectrum was proposed to combat the influence of the PN present.The idea of the PN cancellation is the PN is approximated for the sum of the different frequency between the AP and the MT as well as Doppler shift supposing that the fixed different frequency during several OFDM symbols are identical, so the variable phase may be considered as the combination of the fixed partition and the random partition.The approximation method is utilized to remove the fixed and the random phase partition so that the signal-to-noise ratio (SNR) may be improved.The analysis and the simulation proposed show that the method may effectively improve the performance of the OFDM system.
Portuondo-Campa, Erwin; Kundermann, Stefan; Balet, Laurent; Lecomte, Steve
2015-01-01
We report ultra-low phase-noise microwave generation at a 9.6 GHz carrier frequency from optical frequency combs based on diode-pumped solid-state lasers emitting at telecom wavelength and referenced to a common cavity-stabilized continuous-wave laser. Using a novel fibered polarization-maintaining pulse interleaver, a single-oscillator phase-noise floor of -171 dBc/Hz has been measured with commercial PIN InGaAs photodiodes, constituting a record for this type of detector. Also, a direct optical measurement of the stabilized frequency combs timing jitter was performed using a balanced optical cross correlator, allowing for an identification of the origin of the current phase-noise limitations in the system.
Portuondo-Campa, Erwin; Buchs, Gilles; Kundermann, Stefan; Balet, Laurent; Lecomte, Steve
2015-12-14
We report ultra-low phase-noise microwave generation at a 9.6 GHz carrier frequency from optical frequency combs based on diode-pumped solid-state lasers emitting at telecom wavelength and referenced to a common cavity-stabilized continuous-wave laser. Using a novel fibered polarization-maintaining pulse interleaver, a single-oscillator phase-noise floor of -171 dBc/Hz at 10 MHz offset frequency has been measured with commercial PIN InGaAs photodiodes, constituting a record for this type of detector. Also, a direct optical measurement of the stabilized frequency combs' timing jitter was performed using a balanced optical cross correlator, allowing for an identification of the origin of the phase-noise limitations in the system.
Wu, Yuefeng; Li, Fang; Zhang, Wentao; Xiao, Hao; Liu, Yuliang
2008-11-01
Polarization-induced phase noise in Michelson interferometer with imperfect Faraday rotator mirrors was investigated. This kind of noise generates from the rotation angle errors of Faraday rotator mirrors and external polarization perturbation. The conversion factor κ, representing the magnitude conversion ability from polarization-noise to polarization induced phase-noise, have been theoretically evaluated and experimentally investigated.
Intrinsic 1/f device noise reduction and its effect on phase noise in CMOS ring oscillators
Gierkink, Sander L.J.; Klumperink, Eric A.M.; Wel, van der Arnoud P.; Hoogzaad, Gian; Tuijl, van Ed (A.J.M.); Nauta, Bram
1999-01-01
This paper gives experimental proof of an intriguing physical effect: periodic on-off switching of MOS transistors in a CMOS ring oscillator reduces their intrinsic 1/f noise and hence the oscillator's close-in phase noise. More specifically, it is shown that the 1/f3 phase noise is dependent on the
Phase noise analysis of voltage controlled oscillator used in cesium atomic clock
Zhi, Menghui; Tang, Liang; Qiao, Donghai
2017-03-01
Coherent population trapping (CPT) cesium frequency standard plays a significant role in precision guidance of missile and global positioning system (GPS). Low noise 4.596 GHz voltage controlled oscillator (VCO) is an indispensable part of microwave signal source in cesium frequency standard. Low-phase noise is also the most important and difficult performance indicator of VCO. Starting from phase noise analysis method proposed by Leeson, the formulas about the relationship between phase noise of output signal of oscillator feedback model and phase fluctuation spectrum of amplifier, phase noise of oscillator are derived in this paper. Finally, the asymptote model of microwave oscillator is proposed based on the formula derivation. The experiment shows that when the reverse bias voltage of variode is 1.8 V, the designed oscillation frequency of VCO is 4.596 GHz, the power is ‑1 dBm and the DC power consumption is 19.6 mW. The tendency of phase noise simulation curve and actual test curve conform to asymptote model. The phase noise in 1 and 10 kHz is, respectively, ‑60.86 and ‑86.58 dBc/Hz. The significance of the paper lies in determining the main factors influencing oscillator phase noise and providing guiding direction for the design of low-phase noise VCO.
High phase noise tolerant pilot-tone-aided DP-QPSK optical communication systems
Zhang, Xu; Pang, Xiaodan; Deng, Lei
2012-01-01
In this paper we experimentally demonstrate a novel, high phase-noise tolerant, optical dual polarization (DP) quadrature phase-shift keying (QPSK) communication system based on pilot-tone-aided phase noise cancellation (PNC) algorithm. Vertical cavity surface emitting lasers (VCSELs...
RFID阅读器相位噪声的距离相关效应研究%Study of range correlation effect for RFID reader phase noise
杨海; 何怡刚; 余波; 郭凤鸣
2012-01-01
相位噪声是设计射频系统时的一个重要参数,它对系统性能有很大影响.对于射频识别(RFID)系统,距离相关效应对其相位噪声有重要影响.研究了无源超高频(UHF)RFID阅读器相位调制(PSK)信号的相位噪声表达式,导出距离相关效应时的相位噪声功率谱密度(PSD)和通信误符号率(SER)计算式.距离相关效应下相位噪声的测量和仿真表明,解析结果与测量、仿真结果一致.%Phase noise is an important parameter in designing Radio Frequency(RF) systems since it can have large influence on system performance. In RF Identification (RFID) systems, phase noise is significantly influenced by the range correlation effect. This paper studies the expressions of phase noise for PSK modulation in the passive UHF RFID reader. And the equations of Power Spectra Density(PSD) of phase noise with range correlation effect and Symbol Error Rate(SER) are derived. Measurements and simulation of phase noise with range correlation effect agree well with the computation results of the equations.
A fully integrated W-band push-push CMOS VCO with low phase noise and wide tuning range.
Wang, To-Po
2011-07-01
A circuit topology suitable for a low-phase-noise wide-tuning-range push-push voltage-controlled oscillator (VCO) is proposed in this paper. By applying varactors connected between drain and source terminations of the cross-coupled pair, the tuning range is effectively increased and the phase noise is improved. Moreover, a small capacitor is inserted between the VCO core and testing buffer to reduce loading effects on the VCO core. Furthermore, the enhanced second-harmonic output signal is extracted at middle of the varactors, leading to the elimination of RF choke at VCO's second-harmonic output port and a reduced chip size. Based on the proposed architecture, this VCO fabricated in 0.18-μm CMOS exhibits a measured 6.35% tuning range. Operating at a supply voltage of 1.2 V, the VCO core consumes 7.5-mW dc power, and the measured phase noise is -75 dBc/Hz and -91.5 dBc/Hz at 100-kHz and 1-MHz offsets from the 77.8-GHz carrier, respectively. Compared with previously published silicon-based VCOs over 70 GHz, this work can simultaneously achieve low phase noise, wide tuning range, and low dc power consumption, leading to a superior figure of merit (FOM), and better figure of merit considering the tuning range (FOM(T)). In addition, this fully integrated VCO also demonstrates the highest operation frequency among previously published 0.18-μm CMOS VCOs.
Dai Foster F
2006-01-01
Full Text Available This paper presents a complete noise analysis of a -based fractional- phase-locked loop (PLL based frequency synthesizer. Rigorous analytical and empirical formulas have been given to model various phase noise sources and spurious components and to predict their impact on the overall synthesizer noise performance. These formulas have been applied to an integrated multiband WLAN frequency synthesizer RFIC to demonstrate noise minimization through judicious choice of loop parameters. Finally, predicted and measured phase jitter showed good agreement. For an LO frequency of 4.3 GHz, predicted and measured phase noise was rms and rms, respectively.
2006-01-01
Full Text Available This paper presents a complete noise analysis of a ΣΔ -based fractional- N phase-locked loop (PLL based frequency synthesizer. Rigorous analytical and empirical formulas have been given to model various phase noise sources and spurious components and to predict their impact on the overall synthesizer noise performance. These formulas have been applied to an integrated multiband WLAN frequency synthesizer RFIC to demonstrate noise minimization through judicious choice of loop parameters. Finally, predicted and measured phase jitter showed good agreement. For an LO frequency of 4.3 GHz, predicted and measured phase noise was 0.50 ° rms and 0.535 ° rms, respectively.
Theory of thermal phase noise in Michelson and Sagnac fiber interferometers
Wanser, Keith H.
1994-09-01
The intrinsic thermal phase noise spectra of the Michelson, Michelson with phase conjugate mirrors, and Sagnac fiber optic interferometers are presented. The thermal phase noise is maximum at dc and zero at the loop frequency for the Michelson with ordinary mirrors. Thermal phase noise eliminates the factor of two transducer phase sensitivity advantage of the Michelson over a comparable length Mach Zehnder. The Michelson with two phase conjugate mirrors exhibits identical noise to a Sagnac interferometer with the same total fiber length. The Sagnac exhibits common mode phase noise rejection at low frequencies and a broad maximum in the phase noise at the loop frequency of approximately 1 (mu) rad rms/(root)Hz for a 1 km fiber loop at 1319 nm.
Phase noise due to vibrations in Mach-Zehnder atom interferometers
Miffre, A; Büchner, M; Trénec, G; Vigué, J
2006-01-01
Atom interferometers are very sensitive to accelerations and rotations. This property, which has some very interesting applications, induces a deleterious phase noise due to the seismic noise of the laboratory and this phase noise is sufficiently large to reduce the fringe visibility in many experiments. We develop a model calculation of this phase noise in the case of Mach-Zehnder atom interferometers and we apply this model to our thermal lithium interferometer. We are able to explain the observed phase noise which has been detected through the rapid dependence of the fringe visibility with the diffraction order. We think that the dynamical model developed in the present paper should be very useful to reduce the vibration induced phase noise in atom interferometers, making many new experiments feasible.
Phase noise estimation and mitigation for DCT-based coherent optical OFDM systems.
Yang, Chuanchuan; Yang, Feng; Wang, Ziyu
2009-09-14
In this paper, as an attractive alternative to the conventional discrete Fourier transform (DFT) based orthogonal frequency division multiplexing (OFDM), discrete cosine transform (DCT) based OFDM which has certain advantages over its counterpart is studied for optical fiber communications. As is known, laser phase noise is a major impairment to the performance of coherent optical OFDM (CO-OFDM) systems. However, to our knowledge, detailed analysis of phase noise and the corresponding mitigation methods for DCT-based CO-OFDM systems have not been reported yet. To address these issues, we analyze the laser phase noise in the DCT-based CO-OFDM systems, and propose phase noise estimation and mitigation schemes. Numerical results show that the proposal is very effective in suppressing phase noise and could significantly improve the performance of DCT-based CO-OFDM systems.
Peng, Yu; Jun, Yan; Yin, Shi; Foster, Dai Fa
2010-09-01
A wide-band frequency synthesizer with low phase noise is presented. The frequency tuning range is from 474 to 858 MHz which is compatible with U-band CMMB application while the S-band frequency is also included. Three VCOs with selectable sub-band are integrated on chip to cover the target frequency range. This PLL is fabricated with 0.35 μm SiGe BiCMOS technology. The measured result shows that the RMS phase error is less than 1° and the reference spur is less than -60 dBc. The proposed PLL consumes 20 mA current from a 2.8 V supply. The silicon area occupied without PADs is 1.17 mm2.
Infrared Spectroscopy of Explosives Residues: Measurement Techniques and Spectral Analysis
Phillips, Mark C.; Bernacki, Bruce E.
2015-03-11
Infrared laser spectroscopy of explosives is a promising technique for standoff and non-contact detection applications. However, the interpretation of spectra obtained in typical standoff measurement configurations presents numerous challenges. Understanding the variability in observed spectra from explosives residues and particles is crucial for design and implementation of detection algorithms with high detection confidence and low false alarm probability. We discuss a series of infrared spectroscopic techniques applied toward measuring and interpreting the reflectance spectra obtained from explosives particles and residues. These techniques utilize the high spectral radiance, broad tuning range, rapid wavelength tuning, high scan reproducibility, and low noise of an external cavity quantum cascade laser (ECQCL) system developed at Pacific Northwest National Laboratory. The ECQCL source permits measurements in configurations which would be either impractical or overly time-consuming with broadband, incoherent infrared sources, and enables a combination of rapid measurement speed and high detection sensitivity. The spectroscopic methods employed include standoff hyperspectral reflectance imaging, quantitative measurements of diffuse reflectance spectra, reflection-absorption infrared spectroscopy, microscopic imaging and spectroscopy, and nano-scale imaging and spectroscopy. Measurements of explosives particles and residues reveal important factors affecting observed reflectance spectra, including measurement geometry, substrate on which the explosives are deposited, and morphological effects such as particle shape, size, orientation, and crystal structure.
Mode shape identification using residues of measured offshore structure data
Wang, Chao; Liu, Fushun; Lu, Hongchao
2017-04-01
Compared to traditional mode shape identification methods such as eigensystem realization algorithm (ERA), this article proposes a mode shape identification method based on estimated residues of measured data and the theoretical relationship between the estimated residues and the mode shapes from the state space model is obtained by defining a coefficient matrix. A mass-spring model with five degrees of freedom (DOFs) is utilized to demonstrate the approach. The numerical results indicate that the estimated residues are the mode shapes of structures, but with a coefficient matrix to maintain consistency with the mode shapes from the ERA. Using MATLAB a complicated numerical jacket platform is built to further study the proposed method. The results show that mode shapes consistent with those from the ERA could be obtained by taking the defined coefficient matrix into account, which is also demonstrated by a physical beam model that was built at Ocean University of China.
Does the central limit theorem always apply to phase noise? Some implications for radar problems
Gray, John E.; Addison, Stephen R.
2017-05-01
The phase noise problem or Rayleigh problem occurs in all aspects of radar. It is an effect that a radar engineer or physicist always has to take into account as part of a design or in attempt to characterize the physics of a problem such as reverberation. Normally, the mathematical difficulties of phase noise characterization are avoided by assuming the phase noise probability distribution function (PDF) is uniformly distributed, and the Central Limit Theorem (CLT) is invoked to argue that the superposition of relatively few random components obey the CLT and hence the superposition can be treated as a normal distribution. By formalizing the characterization of phase noise (see Gray and Alouani) for an individual random variable, the summation of identically distributed random variables is the product of multiple characteristic functions (CF). The product of the CFs for phase noise has a CF that can be analyzed to understand the limitations CLT when applied to phase noise. We mirror Kolmogorov's original proof as discussed in Papoulis to show the CLT can break down for receivers that gather limited amounts of data as well as the circumstances under which it can fail for certain phase noise distributions. We then discuss the consequences of this for matched filter design as well the implications for some physics problems.
Phase-noise-induced resonance in arrays of coupled excitable neural models.
Xiaoming Liang; Liang Zhao
2013-08-01
Recently, it is observed that, in a single neural model, phase noise (time-varying signal phase) arising from an external stimulating signal can induce regular spiking activities even if the signal is subthreshold. In addition, it is also uncovered that there exists an optimal phase noise intensity at which the spiking rhythm coincides with the frequency of the subthreshold signal, resulting in a phase-noise-induced resonance phenomenon. However, neurons usually do not work alone, but are connected in the form of arrays or blocks. Therefore, we study the spiking activity induced by phase noise in arrays of globally and locally coupled excitable neural models. We find that there also exists an optimal phase noise intensity for generating large neural response and such an optimal value is significantly decreased compared to an isolated single neuron case, which means the detectability in response to the subthreshold signal of neurons is sharply improved because of the coupling. In addition, we reveal two new resonance behaviors in the neuron ensemble with the presence of phase noise: there exist optimal values of both coupling strength and system size, where the coupled neurons generate regular spikes under subthreshold stimulations, which are called as coupling strength and system size resonance, respectively. Finally, the dependence of phase-noise-induced resonance on signal frequency is also examined.
Enhancement of VCO Linearity and Phase Noise by Implementing Frequency Locked Loop
Ayranci, E; Christensen, K; Andreani, Pietro
2007-01-01
This paper investigates the on-chip implementation of a frequency locked loop (FLL) over a VCO that decreases the phase noise and linearizes the transfer function. Implementation of the FLL inside a PLL is also investigated and a possible application is highlighted. Design of a special kind of low...... noise frequency detector without a reference frequency (frequency-to-voltage converter), which is the most critical component of the FLL, is also presented in a 0.25 mum BiCMOS process. Linearization and approximately 15 dBc/Hz phase noise suppression is demonstrated over a moderate phase noise LC VCO...
Jin, Lei; Xu, Bo; Yamashita, Shinji
2012-11-19
We theoretically and numerically explain the power saturation and the additional phase noise brought by the fiber optical parametric amplifier (FOPA). An equation to calculate an approximation to the saturated signal output power is presented. We also propose a scheme for alleviating the phase noise brought by the FOPA at the saturated state. In simulation, by controlling the decisive factor dispersion difference term Δk of the FOPA, amplitude-noise and additional phase noise reduction of quadrature phase shift keying (QPSK) based on the saturated FOPA is studied, which can provide promising performance to deal with PSK signals.
Coronel, Juan; Varón, Margarita; Rissons, Angélique
2016-09-01
The optical injection locking (OIL) technique is proposed to reduce the phase noise of a carrier generated for a vertical-cavity surface-emitting laser (VCSEL)-based optoelectronic oscillator. The OIL technique permits the enhancement of the VCSEL direct modulation bandwidth as well as the stabilization of the optical noise of the laser. A 2-km delay line, 10-GHz optical injection-locked VCSEL-based optoelectronic oscillator (OILVBO) was implemented. The internal noise sources of the optoelectronic oscillator components were characterized and analyzed to understand the noise conversion of the system into phase noise in the oscillator carrier. The implemented OILVBO phase noise was -105.7 dBc/Hz at 10 kHz from the carrier; this value agrees well with the performed simulated analysis. From the computed and measured phase noise curves, it is possible to infer the noise processes that take place inside the OILVBO. As a second measurement of the oscillation quality, a time-domain analysis was done through the Allan's standard deviation measurement, reported for first time for an optoelectronic oscillator using the OIL technique.
Nonlinear Phase Noise Compensation in Experimental WDM Systems with 256QAM
Yankov, Metodi Plamenov; Da Ros, Francesco; Porto da Silva, Edson
2016-01-01
Nonlinear phase noise (NLPN) is studied in an experimental wavelength division multiplexed (WDM) system operating at 256QAM. Extremely narrow linewidth lasers (phase part of the nonlinear noise in a Raman amplified link. Based...
Residual Gas Fluorescence for Profile Measurements at the GSI UNILAC
Forck, P
2002-01-01
The high beam currents, delivered at the LINAC at GSI (UNILAC) can destroy intercepting diagnostics within one macro-pulse. As an alternative for a non-destructive profile measurement the methode for residual-gas-fluorescence is investigated. The fluorescence light is emitted by the N2 molecules of the residual gas at the blue wavelength range and can be monitored with a modern CCD-camera. The images are transferred via digital bus (IEEE 1394 'FireWire') and the profiles are generated by analysis of the images with a modern software tool (National Instruments 'LabView'). Due to the short beam pulses (about 0.2 ms) the light intensities emitted by the residual gas are low and require a high amplification (gain >106) which is realized with an image intensifier with double MCP (multi channel plate), connected with a fiber taper to the CCD-chip. The design parameters of the optics and electronics are discussed as well as the advantages of the digital data transmission. Measurements with heavy ion beams of several...
SEACAB qualification with Frascati Neutron Generator residual dose measurements
Töre, Candan, E-mail: c.tore@seaingenieria.es; Ortego, Pedro; Rodriguez, Alain
2015-10-15
Highlights: • We developed a new R2S residual dose methodology SEACAB for TBM shield design. • Combines MCNPX mesh tally and ACAB to compute activation in a fast and simple way. • We qualified SEACAB by comparison with second campaign of FNG “duct experiment”. • Calculated dose and flux compare very well with TUD measurements at 7 decay times. • Presently SEACAB is being used in the calculation of residual dose at ITER port 16. - Abstract: The European fusion technology programme considers two test blanket modules, both helium-cooled, one with lithium ceramic pebbles and beryllium and other with Pb–Li eutectic alloy. The high level of neutron flux required for tritium breeding and the neutron multiplication properties of Be and Pb imply the need for a large neutron attenuation in the associated shielding to meet the shutdown dose requirements. A new SEACAB methodology has been developed to apply the rigorous two-step method with the use of the mesh tally of MCNPX and activation code ACAB and it has been qualified with the results of the 2nd campaign of the “duct-experiment” performed with Frascati Neutron Generator in a block of steel and moderator layers with a central cavity where the residual photon flux and dose were measured.
Novel BCH Code Design for Mitigation of Phase Noise Induced Cycle Slips in DQPSK Systems
Leong, M. Y.; Larsen, Knud J.; Jacobsen, G.
2014-01-01
We show that by proper code design, phase noise induced cycle slips causing an error floor can be mitigated for 28 Gbau d DQPSK systems. Performance of BCH codes are investigated in terms of required overhead......We show that by proper code design, phase noise induced cycle slips causing an error floor can be mitigated for 28 Gbau d DQPSK systems. Performance of BCH codes are investigated in terms of required overhead...
Stability and Phase Noise Tests of Two Cryo-Cooled Sapphire Oscillators
Dick, G. John; Wang, Rabi T.
1998-01-01
A cryocooled Compensated Sapphire Oscillator (CSO), developed for the Cassini Ka-band Radio Science experiment, and operating in the 8K - 10K temperature range was previously demonstrated to show ultra-high stability of sigma(sub y) = 2.5 x 10 (exp -15) for measuring times 200 seconds less than or equal to tau less than or equal to 600 seconds using a hydrogen maser as reference. We present here test results for a second unit which allows CSO short-term stability and phase noise to be measured for the first time. Also included are design details of a new RF receiver and an intercomparison with the first CSO unit. Cryogenic oscillators operating below about 10K offer the highest possible short term stability of any frequency sources. However, their use has so far been restricted to research environments due to the limited operating periods associated with liquid helium consumption. The cryocooled CSO is being built in support of the Cassini Ka-band Radio Science experiment and is designed to operate continuously for periods of a year or more. Performance targets are a stability of 3-4 x 10 (exp -15) (1 second less than or equal to tau less than or equal to 100 seconds) and phase noise of -73dB/Hz @ 1Hz measured at 34 GHz. Installation in 5 stations of NASA's deep space network (DSN) is planned in the years 2000 - 2002. In the previous tests, actual stability of the CSO for measuring times tau less than or equal to 200 seconds could not be directly measured, being masked by short-term fluctuations of the H-maser reference. Excellent short-term performance, however, could be inferred by the success of an application of the CSO as local oscillator (L.O.) to the JPL LITS passive atomic standard, where medium-term stability showed no degradation due to L.O. instabilities at a level of (sigma)y = 3 x 10 (exp -14)/square root of tau. A second CSO has now been constructed, and all cryogenic aspects have been verified, including a resonator turn-over temperature of 7.907 K
Dual transponder ranging performance in the presence of oscillator phase noise
赵明臣; 王春晖; 金小军; 金仲和
2015-01-01
A dual transponder carrier ranging method can be used to measure inter-satellite distance with high precision by combining the reference and the to-and-fro measurements. Based on the differential techniques, the oscillator phase noise, which is the main error source for microwave ranging systems, can be significantly attenuated. Further, since the range measurements are derived on the same satellite, the dual transponder ranging system does not need a time tagging system to synchronize the two satellites. In view of the lack of oscillator noise analysis on the dual transponder ranging model, a comprehensive analysis of oscillator noise effects on ranging accuracy is provided. First, the dual transponder ranging system is described with emphasis on the detailed analysis of oscillator noise on measurement precision. Then, a high-fidelity numerical simulation approach based on the power spectrum density of an actual ultra-stable oscillator is carried out in both frequency domain and time domain to support the presented theoretical analysis. The simulation results under different conditions are consistent with the proposed concepts, which makes the results reliable. Besides, the results demonstrate that a high level of accuracy can be achieved by using this oscillator noise cancelation-oriented ranging method.
Residual Stress Measurements After Proof and Flight: ETP-0403
Webster, Ronald L..
1997-01-01
The intent of this testing was to evaluate the residual stresses that occur in and around the attachment details of a case stiffener segment that has been subjected to flight/recovery followed by proof loading. Not measured in this test were stresses relieved at joint disassembly due to out-of-round and interference effects, and those released by cutting the specimens out of the case segment. The test article was lightweight case stiffener segment 1U50715, S/N L023 which was flown in the forward stiffener position on flight SRM 14A and in the aft position on flight SRM24A. Both of these flights were flown with the 3 stiffener ring configuration. Stiffener L023 had a stiffener ring installed only on the aft stub in its first flight, and it had both rings installed on its second flight. No significant post flight damage was found on either flight. Finally, the segment was used on the DM-8 static test motor in the forward position. No stiffener rings were installed. It had only one proof pressurization prior to assignment to its first use, and it was cleaned and proof tested after each flight. Thus, the segment had seen 3 proof tests, two flight pressurizations, and two low intensity water impacts prior to manufacturing for use on DM-8. On DM-8 it received one static firing pressurization in the horizontal configuration. Residual stresses at the surface and in depth were evaluated by both the x-ray diffraction and neutron beam diffraction methods. The x-ray diffraction evaluations were conducted by Technology for Energy Corporation (TEC) at their facilities in Knoxville, TN. The neutron beam evaluations were done by Atomic Energy of Canada Limited (AECL) at the Chalk River Nuclear Laboratories in Ontario. The results showed general agreement with relatively high compressive residual stresses on the surface and moderate to low subsurface tensile residual stresses.
Principles of the measurement of residual stress by neutron diffraction
Webster, G.A.; Ezeilo, A.N. [Imperial Coll. of Science and Technology, London (United Kingdom). Dept. of Mechanical Engineering
1996-11-01
The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs.
Wang, Kai; Yao, Zhanwei; Li, Runbing; Lu, Sibin; Chen, Xi; Wang, Jin; Zhan, Mingsheng
2016-02-10
We report a hybrid scheme for phase-coherent Raman lasers with low phase noise in a wide frequency range. In this scheme, a pair of Raman lasers with a frequency difference of 3.04 GHz is generated by the ±1-order diffracted lights of an acousto-optic modulator (1.52 GHz), where a feedback loop is simultaneously applied for suppressing the phase noise. The beat width of the Raman lasers is narrower than 3 Hz. In the low-frequency range, the phase noise of the Raman lasers is suppressed by 35 dB with the feedback. The phase noise is less than -109 dBc/Hz in the high-frequency range. The sensitivity of an atom gyroscope employing the hybrid Raman lasers can be implicitly improved 10 times. Due to the better high-frequency response, the sensitivity is not limited by the durations of Raman pulses. This work is important for improving the performance of atom-interferometer-based measurements.
Phase noise analysis for OFDM systems based on hot-carrier effects in synchronization electronics
Herlekar, Sameer R.; Zhang, Chi; Wu, Hsiao-Chun; Srivastava, Ashok
2005-05-01
Phase noise may be regarded as the most severe cause of performance degradation in OFDM systems. Hot carriers (HCs), found in the CMOS synchronization circuits, are high-mobility charge carriers that degrade the MOSFET devices" performance by increasing the threshold voltage required to operate the MOSFETs. The HC effect manifests itself as the phase noise, which increases with the continued MOSFET operation and results in the performance degradation of the Voltage-Controlled Oscillator (VCO) built on the MOSFET. The HC effect is particularly evident in the short-channel MOSFET devices. The MOSFET instability will impact on the OFDM system performance. The relationship between the OFDM system performance and the hot carrier effect can be analyzed in terms of a crucial parameter, the MOSFET threshold voltage. In this paper, we derive a general phase noise model for OFDM systems based on the Hot-carrier effect and the corresponding drifted threshold voltage in differential ring oscillators. The expected OFDM performance degradation due to the hot carrier effect is provided through our simulations. We show that the OFDM BER performance evaluation using the existing phase noise models can be upto three orders of magnitude different from the results obtained by using our phase noise model.
Phase-noise limitations in continuous-variable quantum key distribution with homodyne detection
Corvaja, Roberto
2017-02-01
In continuous-variables quantum key distribution with coherent states, the advantage of performing the detection by using standard telecoms components is counterbalanced by the lack of a stable phase reference in homodyne detection due to the complexity of optical phase-locking circuits and to the unavoidable phase noise of lasers, which introduces a degradation on the achievable secure key rate. Pilot-assisted phase-noise estimation and postdetection compensation techniques are used to implement a protocol with coherent states where a local laser is employed and it is not locked to the received signal, but a postdetection phase correction is applied. Here the reduction of the secure key rate determined by the laser phase noise, for both individual and collective attacks, is analytically evaluated and a scheme of pilot-assisted phase estimation proposed, outlining the tradeoff in the system design between phase noise and spectral efficiency. The optimal modulation variance as a function of the phase-noise amount is derived.
Phase noise modeling in LC oscillators implemented in SiGe technology
M.Bouhouche; S.Latreche; C.Gontrand
2013-01-01
This paper addresses phase noise analysis of a radiofrequency LC oscillator built around a SiGe heterojunction bipolar transistor (HBT) realized in a 0.35 μm BiCMOS process,as an active device.First,we give a brief background to SiGe HBT device physics.The key point is to initiate quantitative analysis on the influence of defects induced during extrinsic base implantation on electric performances of this device.These defects are responsible for the current fluctuations at the origin of low frequency noise in BiCMOS technologies.Next,we investigate the effect of implantation defects as a source of noise in semiconductors on the phase noise of a radiofrequency LC oscillator.We observe their influence on the oscillator phase noise,and we quantify the influence of their energy distribution in the semiconductor gap.Second,we give a behavioral model of an LC oscillator containing a SiGe HBT as an active device.The key goal is to study the susceptibility of a radiofrequency oscillator built around a SiGe HBT to phase noise disturbance sources.Based on the time variance behavior of phase noise in oscillators,transient simulations (in the time domain) were used to analyze the time-dependent noise sensitivity of the oscillator.
JPL pulsar timing observations. IV - Excess phase noise
Downs, G. S.; Krause-Polstorff, J.
1986-01-01
Previously published tables of geocentric arrival times for 24 pulsars covering a 12 year span are extended here to 14.5 years. The list of pulsars is extended by nine, most of which were observed for about 4 years. Known positins of these new objects are confirmed, and limits on the proper motions are obtained. Large phase excursions in PSR 0525 + 21 are found. The orbital parameters of the binary pulsar 0820 + 02 are tentatively confirmed. Short-term timing noise in excess of that expected from receiver considerations alone is established. Variations in the timing residuals for the original 24 pulsars are analyzed for correlations with other observable parameters. Little significant correlation with changes in pulse shape or energy or with the drift correction is found on time scales of 500 pulses or longer.
An integrated low phase noise radiation-pressure-driven optomechanical oscillator chipset
Luan, X; Li, Y; McMillan, J F; Zheng, J; Huang, S -W; Hsieh, P -C; Gu, T; Wang, D; Hati, A; Howe, D A; Wen, G; Yu, M; Lo, G; Kwong, D -L; Wong, C W
2014-01-01
High-quality frequency references are the cornerstones in position, navigation and timing applications of both scientific and commercial domains. Optomechanical oscillators, with direct coupling to continuous-wave light and non-material-limited f Q product, are long regarded as a potential platform for frequency reference in radio-frequency-photonic architectures. However, one major challenge is the compatibility with standard CMOS fabrication processes while maintaining optomechanical high quality performance. Here we demonstrate the monolithic integration of photonic crystal optomechanical oscillators and on-chip high speed Ge detectors based on the silicon CMOS platform. With the generation of both high harmonics (up to 59th order) and subharmonics (down to 1/4), our chipset provides multiple frequency tones for applications in both frequency multipliers and dividers. The phase noise is measured down to -125 dBc/Hz at 10 kHz offset at ~ 400 {\\mu}W dropped-in powers, one of the lowest noise optomechanical o...
An integrated low phase noise radiation-pressure-driven optomechanical oscillator chipset.
Luan, Xingsheng; Huang, Yongjun; Li, Ying; McMillan, James F; Zheng, Jiangjun; Huang, Shu-Wei; Hsieh, Pin-Chun; Gu, Tingyi; Wang, Di; Hati, Archita; Howe, David A; Wen, Guangjun; Yu, Mingbin; Lo, Guoqiang; Kwong, Dim-Lee; Wong, Chee Wei
2014-10-30
High-quality frequency references are the cornerstones in position, navigation and timing applications of both scientific and commercial domains. Optomechanical oscillators, with direct coupling to continuous-wave light and non-material-limited f × Q product, are long regarded as a potential platform for frequency reference in radio-frequency-photonic architectures. However, one major challenge is the compatibility with standard CMOS fabrication processes while maintaining optomechanical high quality performance. Here we demonstrate the monolithic integration of photonic crystal optomechanical oscillators and on-chip high speed Ge detectors based on the silicon CMOS platform. With the generation of both high harmonics (up to 59 th order) and subharmonics (down to 1/4), our chipset provides multiple frequency tones for applications in both frequency multipliers and dividers. The phase noise is measured down to -125 dBc/Hz at 10 kHz offset at ~400 μW dropped-in powers, one of the lowest noise optomechanical oscillators to date and in room-temperature and atmospheric non-vacuum operating conditions. These characteristics enable optomechanical oscillators as a frequency reference platform for radio-frequency-photonic information processing.
A Low Phase Noise CMOS Quadrature Voltage Control Oscillator Using Clock Gated Technique
Jothi Baskar A
2015-06-01
Full Text Available This project presents the low phase noise cmos quadrature voltage control oscillator using clock gating technique. Here the colpitts vco is used to split the capacitance in the Qvco circuit producing quadrature output. The startup condition in the oscillator is improved by using enhancement [12].This QVCO performs the operation anti phase injection locking fordevice reuse [8]. The new clock gating technique is used to reduce the power with thepower supply 1.5v. The QVCO uses a 0.5mwith phase error of 0.4 and exhibits a phase noise of -118dBc/HZ at 1MHZ offset at the centre frequency of 500MHZ. Index terms: current switching, clock gating, phase noise, Qvco
Low-Complexity Tracking of Laser and Nonlinear Phase Noise in WDM Optical Fiber Systems
Yankov, Metodi Plamenov; Fehenberger, Tobias; Barletta, Luca
2015-01-01
In this paper, the wavelength division multiplexed (WDM) fiber optic channel is considered. It is shown that for ideal distributed Raman amplification (IDRA), the Wiener process model is suitable for the non-linear phase noise due to cross phase modulation from neighboring channels. Based...... compared to previous trellis-based approaches, which require numerical integration. Further, the proposed method performs very well in low-to-moderate signal-to-noise ratio (SNR), where standard decision directed (DD) methods, especially for high-order modulation, fail. The proposed algorithm does not rely...... on this model, a phase noise tracking algorithm is presented. We approximate the distribution of the phase noise at each time instant by a mixture of Tikhonov distributions, and derive a closed form expression for the posterior probabilities of the input symbols. This reduces the complexity dramatically...
Ultra-low phase noise all-optical microwave generation setup based on commercial devices
Didier, A; Grop, S; Dubois, B; Bigler, E; Rubiola, E; Lacroûte, C; Kersalé, Y
2015-01-01
In this paper, we present a very simple design based on commercial devices for the all-optical generation of ultra-low phase noise microwave signals. A commercial, fibered femtosecond laser is locked to a laser that is stabilized to a commercial ULE Fabry-Perot cavity. The 10 GHz microwave signal extracted from the femtosecond laser output exhibits a single sideband phase noise $\\mathcal{L}(f)=-104 \\ \\mathrm{dBc}/\\mathrm{Hz}$ at 1 Hz Fourier frequency, at the level of the best value obtained with such "microwave photonics" laboratory experiments \\cite{Fortier2011}. Close-to-the-carrier ultra-low phase noise microwave signals will now be available in laboratories outside the frequency metrology field, opening up new possibilities in various domains.
Yi, Xingwen; Chen, Xuemei; Sharma, Dinesh; Li, Chao; Luo, Ming; Yang, Qi; Li, Zhaohui; Qiu, Kun
2014-06-02
Digital coherent superposition (DCS) provides an approach to combat fiber nonlinearities by trading off the spectrum efficiency. In analogy, we extend the concept of DCS to the optical OFDM subcarrier pairs with Hermitian symmetry to combat the linear and nonlinear phase noise. At the transmitter, we simply use a real-valued OFDM signal to drive a Mach-Zehnder (MZ) intensity modulator biased at the null point and the so-generated OFDM signal is Hermitian in the frequency domain. At receiver, after the conventional OFDM signal processing, we conduct DCS of the optical OFDM subcarrier pairs, which requires only conjugation and summation. We show that the inter-carrier-interference (ICI) due to phase noise can be reduced because of the Hermitain symmetry. In a simulation, this method improves the tolerance to the laser phase noise. In a nonlinear WDM transmission experiment, this method also achieves better performance under the influence of cross phase modulation (XPM).
Using of abrasive water jet for measurement of residual stress in railway wheels
Hlaváček, P. (Petr); Brumek, J.; Horsák, L.
2012-01-01
The paper provides a general introduction to methods of measurement of residual stresses on railway wheels. Determination of residual stress distribution is necessary for the prediction of wheel service life and possible catastrophic failure. Therefore experimental section is devoted to residual stress measurement using strain gauges according to standard EN 13262 + A1. During measurement, several segments of tested wheel were cut by abrasive water jet to detect changes of residual stresses o...
Atomic-ensemble-based quantum repeater against general polarization and phase noise
Zhang Binbin [Department of Electronical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States); Xu Yaqiong [Department of Electronical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)
2011-07-15
We present a quantum repeater architecture based on atomic ensembles, which is free of polarization and phase noise. With only simple optical elements, we can obtain the uncorrupted entanglement in the noisy channel. Even if the channel suffers from the general polarization and phase noise, the fidelity of transmitted qubits in our protocol can be stable and have no dependence on the noise parameter, which is a significant advantage compared with previous protocols. Moveover, we can even improve the fidelity by using time delayers. The proposed quantum repeater is feasible and useful in the long-distance quantum entanglement distribution and may be promising in other quantum-information applications.
Capacity of Discrete-Time Wiener Phase Noise Channels to Within a Constant Gap
Barletta, Luca; Rini, Stefano
2017-01-01
The capacity of the discrete-time channel affected by both additive Gaussian noise and Wiener phase noise is studied. Novel inner and outer bounds are presented, which differ of at most $6.65$ bits per channel use for all channel parameters. The capacity of this model can be subdivided in three regimes: (i) for large values of the frequency noise variance, the channel behaves similarly to a channel with circularly uniform iid phase noise; (ii) when the frequency noise variance is small, the e...
Xiushan, Wu; Zhigong, Wang; Zhiqun, Li; Jun, Xia; Qing, Li
2010-08-01
A fully integrated cross-coupled LC tank voltage-controlled oscillator (LC-VCO) using transformer feedback is proposed to achieve a low phase noise and ultra-low-power design even at a supply below the threshold voltage. The ultra-low-power VCO is implemented in the mixed-signal and RF 1P6M 0.18-μm CMOS technology of SMIC. The measured phase noise is -125.3 dBc/Hz at an offset frequency of 1 MHz from a carrier of 2.433 GHz, while the VCO core circuit draws only 640 μW from a 0.4-V supply. The designed VCO can cover a frequency range from 2.28 to 2.48 GHz. The tuning range of the circuit is 200 MHz (8.7%) and the FOM is -195.7 dB, which is suitable for an IEEE 802.11b receiver.
Gastric residual volume (GRV) and gastric contents measurement by refractometry.
Chang, Wei-Kuo; McClave, Stephen A; Hsieh, Chung-Bao; Chao, You-Chen
2007-01-01
Traditional use of gastric residual volumes (GRVs), obtained by aspiration from a nasogastric tube, is inaccurate and cannot differentiate components of the gastric contents (gastric secretion vs delivered formula). The use of refractometry and 3 mathematical equations has been proposed as a method to calculate the formula concentration, GRV, and formula volume. In this paper, we have validated these mathematical equations so that they can be implemented in clinical practice. Each of 16 patients receiving a nasogastric tube had 50 mL of water followed by 100 mL of dietary formula (Osmolite HN, Abbott Laboratories, Columbus, OH) infused into the stomach. After mixing, gastric content was aspirated for the first Brix value (BV) measurement by refractometry. Then, 50 mL of water was infused into the stomach and a second BV was measured. The procedure of infusion of dietary formula (100 mL) and then water (50 mL) was repeated and followed by subsequent BV measurement. The same procedure was performed in an in vitro experiment. Formula concentration, GRV, and formula volume were calculated from the derived mathematical equations. The formula concentrations, GRVs, and formula volumes calculated by using refractometry and the mathematical equations were close to the true values obtained from both in vivo and in vitro validation experiments. Using this method, measurement of the BV of gastric contents is simple, reproducible, and inexpensive. Refractometry and the derived mathematical equations may be used to measure formula concentration, GRV, and formula volume, and also to serve as a tool for monitoring the gastric contents of patients receiving nasogastric feeding.
Chitgarha, Mohammad Reza; Khaleghi, Salman; Ziyadi, Morteza; Mohajerin-Ariaei, Amirhossein; Almaiman, Ahmed; Daab, Wajih; Rogawski, Devora; Tur, Moshe; Touch, Joseph D; Langrock, Carsten; Fejer, Martin M; Willner, Alan E
2014-05-15
We propose and demonstrate an all-optical phase noise reduction scheme that uses optical nonlinear mixing and tunable optical delays to suppress the low-speed phase noise induced by laser linewidth. By utilizing the phase conjugate copy of the original signal and two narrow-linewidth optical pumps, the phase noise induced by laser linewidth can be reduced by a factor of ∼5 for a laser with 500-MHz phase noise bandwidth. The error-vector-magnitude can be improved from ∼30% to ∼14% for the same laser linewidth for 40-Gbit/s quadrature phase shift keying signal.
Peijun, Gao; J, Oh N.; Hao, Min
2009-08-01
A differential LC voltage controlled oscillator (VCO) employing parasitic vertical-NPN (V-NPN) transistors as a negative gm-cell is presented to improve the close-in phase noise. The V-NPN transistors have lower flicker noise compared to MOS transistors. DC and AC characteristics of the V-NPN transistors are measured to facilitate the VCO design. The proposed VCO is implemented in a 0.18 μm CMOS RF/mixed signal process, and the measurement results show the close-in phase noise is improved by 3.5-9.1 dB from 100 Hz to 10 kHz offset compared to that of a similar CMOS VCO. The proposed VCO consumes only 0.41 mA from a 1.5 V power supply.
Low-complexity BCH codes with optimized interleavers for DQPSK systems with laser phase noise
Leong, Miu Yoong; Larsen, Knud J.; Jacobsen, Gunnar
2017-01-01
The presence of high phase noise in addition to additive white Gaussian noise in coherent optical systems affects the performance of forward error correction (FEC) schemes. In this paper, we propose a simple scheme for such systems, using block interleavers and binary Bose–Chaudhuri–Hocquenghem (...
ICI mitigation in concurrent multi-band receiver due to the phase noise and IQ imbalance
Lee, Hui-Kyu; Ryu, Heung-Gyoon
2012-06-01
For the next generation long-term evolution (LTE) advanced mobile communication system, 100 MHz bandwidth and 1 Gbit/s data speed are needed. However, there is not enough and wide vacant frequency band. Therefore, spectrum aggregation method has been studied to extend available frequency bands. Frequency synthesiser and power amplifier of transceiver should cover this wide bandwidth. The phase noise and In-phase and quadrature (IQ) imbalance would increase, which would be a serious problem in this transceiver. Also, signal-to-noise ratio becomes degraded because of nonlinearity and the quantisation noises of the Analog-to-digital conversion (ADC) in the receiver. Uplink of LTE-advanced uses Aggregated DFT-spread (NxDFT-S) orthogonal frequency division multiplexing (OFDM) signals. Since the effect of the phase noise and IQ imbalance are more serious in the multi-band Discrete Fourier transform (DFT)-spreading OFDM system, we like to analyse the effect of inter-carrier interference in frequency domain of receiver and the degradation of bit error rate (BER) performance. Also, by the channel response in frequency domain of the uplink system, we separate phase noise and IQ imbalance effect. Finally, we like to propose a compensation method that estimates the channel exactly and removes IQ imbalance and phase noise. Simulation result shows that the proposed method achieves the 2 dB performance gain of BER = 10-4.
A study of phase noise in colpitts and LC-tank CMOS oscillators
Andreani, Pietro; Wang, Xiaoyan; Vandi, Luca
2005-01-01
This paper presents a study of phase noise in CMOS Colpitts and LC-tank oscillators. Closed-form symbolic formulas for the 1/f(2) phase-noise region are derived for both the Colpitts oscillator (either single-ended or differential) and the LC-tank oscillator, yielding highly accurate results under...... very general assumptions. A comparison between the differential Colpitts and the LC-tank oscillator is also carried out, which shows that the latter is capable of a 2-dB lower phase-noise figure-of-merit (FoM) when simplified oscillator designs and ideal MOS models are adopted. Several prototypes...... of both Colpitts and LC-tank oscillators have been implemented in a 0.35-mu m CMOS process. The best performance of the LC-tank oscillators shows a phase noise of -142 dBc/Hz at 3-MHz offset frequency from a 2.9-GHz carrier with a 16-mW power consumption, resulting in an excellent FoM of similar to 189 d...
Phase Noise Monitor and Reduction by Parametric Saturation Approach in Phase Modulation Systems
XU Ming; ZHOU Zhen; PU Xiao; JI Jian-Hua; YANG Shu-Wen
2011-01-01
Nonlinear phase noise (NLPN) is investigated theoretically and numerically to be mitigated by parametric saturation approach in DPSK systems.The nonlinear propagation equation that incorporates the phase of linear and nonlinear is analyzed with parametric saturation processing (PSP).The NLPN is picked and monitored with the power change factors in the DPSK system.This process can be realized by an optical PSP limiter and a novel apparatus with feedback MZI.The monitor range of phase noise is 0°-90°, which may be reduced to 0°-45°if the monitor factor is about the Stockes wave but not an anti-Stockes wave.It is shown that DPSK signal performance can be improved based on the parametric saturation approach.%@@ Nonlinear phase noise (NLPN) is investigated theoretically and numerically to be mitigated by parametric saturation approach in DPSK systems.The nonlinear propagation equation that incorporates the phase of linear and nonlinear is analyzed with parametric saturation processing (PSP).The NLPN is picked and monitored with the power change factors in the DPSK system.This process can be realized by an optical PSP limiter and a novel apparatus with feedback MZI.The monitor range of phase noise is 0°-90°, which may be reduced to 0°-45° if the monitor factor is about the Stockes wave but not an anti-Stockes wave.It is shown that DPSK signal performance can be improved based on the parametric saturation approach.
Experimental Study of Nonlinear Phase Noise and its Impact on WDM Systems with DP-256QAM
Yankov, Metodi Plamenov; Da Ros, Francesco; Porto da Silva, Edson
2016-01-01
A probabilistic method for mitigating the phase noise component of the non-linear interference in WDM systems with Raman amplification is experimentally demonstrated. The achieved gains increase with distance and are comparable to the gains of single-channel digital back-propagation....
Phase noise reduction by self-phase locking in semiconductor lasers using phase conjugate feedback
Petersen, Lykke; Gliese, Ulrik Bo; Nielsen, Torben Nørskov
1994-01-01
A theoretical analysis of the behavior of the frequency/phase noise of semiconductor lasers with external phase conjugate feedback is presented. It is shown that the frequency noise is drastically reduced even for lasers with butt-coupled phase conjugate mirrors. In this laser system, the phase...
Low-Complexity Tracking of Laser and Nonlinear Phase Noise in WDM Optical Fiber Systems
Yankov, Metodi Plamenov; Fehenberger, Tobias; Barletta, Luca;
2015-01-01
In this paper, the wavelength division multiplexed (WDM) fiber optic channel is considered. It is shown that for ideal distributed Raman amplification (IDRA), the Wiener process model is suitable for the non-linear phase noise due to cross phase modulation from neighboring channels. Based...
Hot carrier effects on jitter and phase noise in CMOS voltage-controlled oscillators
Zhang, Chi; Srivastava, Ashok
2005-05-01
The effects of hot carrier stress on CMOS voltage-controlled oscillators (VCO) are investigated. A model of the threshold voltage degradation in MOSFETs due to hot carrier stress has been used to model jitter and phase noise in voltage-controlled oscillators. The relation between the stress time which induces the hot carrier effects and the degradation of the VCO performance is presented. The VCO performance degradation takes into consideration decrease in operation frequency, increase in jitter and phase noise and decrease in tuning range. The experimental circuits have been designed in 0.5 μm n-well CMOS technology for operation at 3 V. It is shown that when the MOSFET threshold voltage, increases from 0.4 V to 0.9 V due to the hot carrier effect, for the single-ended ring oscillator, the oscillation frequency changes from 538 MHz to 360 MHz, and the phase noise changes from -104 dBc to -105 dBc at 1 MHz frequency offset with a power dissipation of 0.37 mW. For the current-starved VCO, the tuning range changes from 72 MHz - 287 MHz to 65.4 MHz - 201 MHz, and the phase noise changes from -109 dBc to -107 dBc at 1 MHz offset from the center frequency, 200 MHz; for the double-ended differential VCO, the tuning range changes from 32 MHz - 983 MHz to 26 MHz - 698 MHz, and phase noise changes from -86 dBc to -87 dBc at 1 MHz offset from the center frequency, 700 MHz.
Shambayati, S.
1999-10-01
In order to reduce the cost of deep-space missions, NASA is exploring the possibility of using new, cheaper technologies. Among these is the possibility of replacing ultra-stable oscillators (USOs) onboard the spacecraft with oscillators with measurable phase noise. In addition, it is proposed that these spacecraft use higher 32-GHz (Ka-band) radio frequencies in order to save mass. In this article, the performance of a convolutionally encoded deep-space link using non-USO-type oscillators onboard the spacecraft at Ka-band is analyzed. It is shown that the ground-receiver tracking-loop bandwidth settings need to be optimized and that, by selecting an oscillator with good phase-noise characteristics, the minimum required power onboard the spacecraft could be reduced by as much as 10 dB.
Measurement of Residual Stress in a Welded Branch Connection and Effects on Fracture Behaviour
Law, M.; Luzin, V.; Kirstein, O.
2010-11-01
The branch analysed in this paper was not post weld heat treated, resulting in significant residual stresses. Assessment codes assume these to be at, or close to, yield. An integrity assessment of a welded branch connection was carried out using these high assumed residual stresses. The weld then had residual stresses determined by neutron diffraction, performed using ANSTO's residual stress diffractometer, Kowari. The maximum measured residual stress (290 MPa or 60% of yield) was much lower than the yield value assumed by assessment codes. Reanalysing with the actual residual stresses almost doubled the critical crack size, increasing the safety of the connection.
Amplitude and phase noises of a spin-transfer nano-oscillator synchronized by a phase-lock loop
Mitrofanov, A. A.; Safin, A. R.; Udalov, N. N.
2015-08-01
We have studied the amplitude and phase noises of a spin-transfer nano-oscillator (STNO) with a phase synchronization system (phase-lock loop, PLL). Spectral characteristics of the amplitude and phase noises of the isochronous and nonisochronous STNO are obtained and compared to the analogous characteristics of an autonomous (nonsynchronized) oscillator. The PLL bandwidth is determined.
杜丹
2015-01-01
针对深空测控系统高精度测量对于信道附加相噪的要求,采用直接数字频率合成( DDS )正交调制方法设计频率综合器。通过巧妙的试验和外推方法,择优选取电压型鉴相器,在锁相环相噪模型的基础上,全面分析各部分相噪的贡献,综合设计环路带宽,有效控制附加相噪,实现低相噪频综器最理想的目标,即环路带内的相噪完全由参考决定,带外的相噪由压控振荡器( VCO)决定,并采用两源互比的方法完成1 Hz极低相位噪声的测试,测试结果为-73 dBc/Hz,与设计结果完全一致。该方法对于测控站极低相噪的设计具有一定参考价值。%For the additional phase noise requirements on channels in deep space TT&C system with high ac-curacy measurement,a frequency synthesizer is designed using direct digital synthesizing(DDS) quadrature modulation. A voltage-type phase discriminator is selected by smart test and extrapolation method. Based on phase noise model of phase locked loop,contributions from all parts of phase noise are analyzed. So the idea-lest performance of frequency synthesizer with low phase noise,i. e. loop in-band phase noise is depended on reference frequency,and out-band phase noise is determined by voltage-controlled oscillator(VCO),is implemented by loop bandwidth integrated design and efficient additional phase noise control. The 1 Hz low phase noise is tested through comparing two sources and it is-73 dBc/Hz,which is consistent with design re-sult. This method is valuable to low phase noise design in deep space TT&C ground station.
Measurable residual disease testing in acute myeloid leukaemia.
Hourigan, C S; Gale, R P; Gormley, N J; Ossenkoppele, G J; Walter, R B
2017-07-01
There is considerable interest in developing techniques to detect and/or quantify remaining leukaemia cells termed measurable or, less precisely, minimal residual disease (MRD) in persons with acute myeloid leukaemia (AML) in complete remission defined by cytomorphological criteria. An important reason for AML MRD-testing is the possibility of estimating the likelihood (and timing) of leukaemia relapse. A perfect MRD-test would precisely quantify leukaemia cells biologically able and likely to cause leukaemia relapse within a defined interval. AML is genetically diverse and there is currently no uniform approach to detecting such cells. Several technologies focused on immune phenotype or cytogenetic and/or molecular abnormalities have been developed, each with advantages and disadvantages. Many studies report a positive MRD-test at diverse time points during AML therapy identifies persons with a higher risk of leukaemia relapse compared with those with a negative MRD-test even after adjusting for other prognostic and predictive variables. No MRD-test in AML has perfect sensitivity and specificity for relapse prediction at the cohort- or subject levels and there are substantial rates of false-positive and -negative tests. Despite these limitations, correlations between MRD-test results and relapse risk have generated interest in MRD-test result-directed therapy interventions. However, convincing proof that a specific intervention will reduce relapse risk in persons with a positive MRD-test is lacking and needs testing in randomized trials. Routine clinical use of MRD-testing requires further refinements and standardization/harmonization of assay platforms and results reporting. Such data are needed to determine whether results of MRD-testing can be used as a surrogate end point in AML therapy trials. This could make drug-testing more efficient and accelerate regulatory approvals. Although MRD-testing in AML has advanced substantially, much remains to be done.
Effects of cutting and specimen size on neutron measurement of residual stresses
Law, M.; Luzin, V.; Kirstein, O.
2010-11-01
To perform neutron residual stress measurements it is often necessary to cut samples to a manageable size. The effects of cutting a girth welded pipe were investigated with analytical methods and finite element analysis. The effect of cutting on measured stresses was calculated. A simplified method of modelling residual stresses in welds, "chill modelling", is introduced. In ring slitting a cut is made in the axial direction and the deformation is maeesured. The change in elastic stress can be calculated and added to neutron diffraction measurements made on a cut ring to calculate the original stresses. Residual stress measurements were performed to validate the ring slitting correction using ANSTO's residual stress diffractometer Kowari.
Grosche, Gesine
2013-01-01
Single-mode optical fiber is a highly efficient connecting medium, used not only for optical telecommunications but also for the dissemination of ultra-stable frequencies or timing signals. In 1994, Ma, Jungner, Ye and Hall described a measurement and control system to deliver the same optical frequency at two places, namely the two ends of a fiber, by eliminating the "fiber-induced phase-noise modulation, which corrupts high-precision frequency-based applications". We present a simple detection and control scheme to deliver the same optical frequency at many places anywhere along a transmission path, or in its vicinity, with a relative instability of 1 part in $10^{19}$. The same idea applies to radio frequency and timing signals. This considerably simplifies future efforts to make precise timing/frequency signals available to many users, as required in some large scale science experiments.
R. A. Bosch
2006-09-01
Full Text Available In an electron storage ring, coupling between dipole and quadrupole Robinson oscillations modifies the spectrum of longitudinal beam oscillations driven by radio-frequency (rf generator phase noise. In addition to the main peak at the resonant frequency of the coupled dipole Robinson mode, another peak occurs at the resonant frequency of the coupled quadrupole mode. To describe these peaks analytically for a quadratic synchrotron potential, we include the dipole and quadrupole modes when calculating the beam response to generator noise. We thereby obtain the transfer function from generator-noise phase modulation to beam phase modulation with and without phase feedback. For Robinson-stable bunches confined in a synchrotron potential with a single minimum, the calculated transfer function agrees with measurements at the Aladdin 800-MeV electron storage ring. The transfer function is useful in evaluating phase feedback that suppresses Robinson oscillations in order to obtain quiet operation of an infrared beam line.
A 220-1100 MHz low phase-noise frequency synthesizer with wide-band VCO and selectable I/Q divider
Hua, Chen; Renjie, Gong; Xu, Cheng; Yulin, Zhang; Zhong, Gao; Guiliang, Guo; Yuepeng, Yan
2014-12-01
This paper presents a low phase-noise fractional-N frequency synthesizer which provides an in-phase/quadrature-phase (I/Q) signal over a frequency range of 220-1100 MHz for wireless networks of industrial automation (WIA) applications. Two techniques are proposed to achieve the wide range. First, a 1.4-2.2 GHz ultralow gain voltage-controlled oscillator (VCO) is adopted by using 128 tuning curves. Second, a selectable I/Q divider is employed to divide the VCO frequency by 2 or 3 or 4 or 6. Besides, a phase-switching prescaler is proposed to lower PLL phase noise, a self-calibrated charge pump is used to suppress spur, and a detect-boosting phase frequency detector is adopted to shorten settling time. With a 200 kHz loop bandwidth, lowest measured phase noise is -106 dBc/Hz at a 10 kHz offset and -131 dBc/Hz at a 1 MHz offset. Fabricated in the TSMC 0.18 μm CMOS process, the synthesizer occupies a chip area of 1.2 mm2, consumes only 15 mW from the 1.8 V power supply, and settles within 13.2 μs. The synthesizer is optimized for the WIA applications, but can also be used for other short-range wireless communications, such as 433, 868, 916 MHz ISM band applications.
Wang, Sen
2014-09-01
In this paper, a Ka-band CMOS push-push voltage- controlled oscillator (VCO) integrated into a glass-integrated passive device (GIPD) process is presented. The transformer, λ/4 transmission line, and inductors of the VCO are realized in the GIPD process, achieving superior performances, and therefore improve the phase noise of the VCO. Moreover, the transformer-based VCO is a differential Hartley topology to further reduce the phase noise and chip area. Operating at 1.8 V supply voltage, the VCO core consumes merely 3.8 mW of dc power. The measured phase noise is -109.18 dBc/Hz at 1 MHz offset from the 30.84 GHz oscillation frequency. The push-push VCO also demonstrates a 24.5 dB fundamental rejection, and exhibits an 8.4% tuning range. Compared with recently published CMOS-based VCOs, it is observed that the proposed VCO exhibits excellent performance under low power consumption.
Optical phase noise engineering via acousto-optic interaction and its interferometric applications
Satapathy, Nandan; Bannerjee, Sourish; Ramachandran, Hema
2013-01-01
We exercise rapid and fine control over the phase of light by transferring digitally gen- erated phase jumps from radio frequency (rf) electrical signals onto light by means of acousto-optic interaction. By tailoring the statistics of phase jumps in the electrical signal and thereby engineering the optical phase noise, we manipulate the visibil- ity of interference fringes in a Mach-Zehnder interferometer that incorporates two acousto-optic modulators. Such controlled dephasing finds applications in modern experiments involving the spread or diffusion of light in an optical network. Further, we analytically show how engineered partial phase noise can convert the dark port of a stabilised interferometer to a weak source of highly correlated photons.
Low phase noise GaAs HBT VCO in Ka-band
Ting, Yan; Yuming, Zhang; Hongliang, Lü; Yimen, Zhang; Yue, Wu; Yifeng, Liu
2015-02-01
Design and fabrication of a Ka-band voltage-controlled oscillator (VCO) using commercially available 1-μm GaAs heterojunction bipolar transistor technology is presented. A fully differential common-emitter configuration with a symmetric capacitance with a symmetric inductance tank structure is employed to reduce the phase noise of the VCO, and a novel π-feedback network is applied to compensate for the 180° phase shift. The on-wafer test shows that the VCO exhibits a phase noise of -96.47 dBc/Hz at a 1 MHz offset and presents a tuning range from 28.312 to 28.695 GHz. The overall dc current consumption of the VCO is 18 mA with a supply voltage of -6 V The chip area of the VCO is 0.7 × 0.7 mm2.
Frequency Estimation of Single-Tone Sinusoids Under Additive and Phase Noise
Asmaa Nazar Almoosawy; Zahir M. Hussain; Fadel A. Murad
2014-01-01
We investigate the performance of main frequency estimation methods for a single-component complex sinusoid under complex additive white Gaussian noise (AWGN) as well as phase noise (PN). Two methods are under test: Maximum Likelihood (ML) method using Fast Fourier Transform (FFT), and the autocorrelation method (Corr). Simulation results showed that FFT-method has superior performance as compared to the Corr-method in the presence of additive white Gaussian noise (affecting the amplitude) an...
Unscented Kalman filters for polarization state tracking and phase noise mitigation.
Jignesh, Jokhakar; Corcoran, Bill; Zhu, Chen; Lowery, Arthur
2016-09-19
Simultaneous polarization and phase noise tracking and compensation is proposed based on an unscented Kalman filter (UKF). We experimentally demonstrate the tracking under noise-loading and after 800-km single-mode fiber transmission with 20-Gbaud QPSK and 16-QAM signals. These experiments show that the proposed UKF outperforms both conventional blind tracing algorithms and a previously proposed extended Kalman filter, at the cost of higher complexity. Additionally, we propose and test modified Kalman filter algorithms to reduce computational complexity.
Low Phase Noise SiGe Push-Push Oscillators for Millimeter Wave Frequencies
2008-01-01
In this thesis low phase noise SiGe HBT monolithically integrated push-push oscillators for millimeter wave frequency generation are investigated. Nonlinear simulation methods for oscillator signal and noise analysis and device physics at high currents and high voltages are discussed. Push-push oscillators with output frequencies from 63 GHz up to 280 GHz were designed and after fabrication in an external foundry investigated experimentally. For automotive radar applications a VCO with a cent...
A Monolithic Radiation-Pressure Driven, Low Phase Noise Silicon Nitride Opto-Mechanical Oscillator
Tallur, Siddharth; Bhave, Sunil A
2011-01-01
Cavity opto-mechanics enabled radiation pressure (RP) driven oscillators shown in the past offer an all optical Radio Frequency (RF) source without the need for external electrical feedback. However these oscillators require external tapered fiber or prism coupling and non-standard fabrication processes. In this work, we present a CMOS compatible fabrication process to design high optical quality factor opto-mechanical resonators in silicon nitride. The ring resonators designed in this process demonstrate low phase noise RP driven oscillations. Using integrated grating couplers and waveguide to couple light to the micro-resonator eliminates 1/f^3 and other higher order phase noise slopes at close-to-carrier frequencies present in previous demonstrations. We present an RP driven OMO operating at 41.97MHz with a signal power of -11dBm and phase noise of -85dBc/Hz at 1kHz offset with only 1/f^2 noise down to 10Hz offset from carrier.
Joint Channel and Phase Noise Estimation in MIMO-OFDM Systems
Ngebani, I. M.; Chuma, J. M.; Zibani, I.; Matlotse, E.; Tsamaase, K.
2017-05-01
The combination of multiple-input multiple-output (MIMO) techniques with orthogonal frequency division multiplexing (OFDM), MIMO-OFDM, is a promising way of achieving high spectral efficiency in wireless communication systems. However, the performance of MIMO-ODFM systems is highly degraded by radio frequency (RF) impairments such as phase noise. Similar to the single-input single-output (SISO) case, phase noise in MIMO-OFDM systems results in a common phase error (CPE) and inter carrier interference (ICI). In this paper the problem of joint channel and phase noise estimation in a system with multiple transmit and receive antennas where each antenna is equipped with its own independent oscillator is tackled. The technique employed makes use of a novel placement of pilot carriers in the preamble and data portion of the MIMO-OFDM frame. Numerical results using a 16 and 64 quadrature amplitude modulation QAM schemes are provided to illustrate the effectiveness of the proposed scheme for MIMO-OFDM systems.
A low-phase-noise 18 GHz Kerr frequency microcomb phase-locked over 65 THz
Huang, S -W; Zhou, H; Yu, M; Kwong, D -L; Wong, C W
2015-01-01
Laser frequency combs are coherent light sources that simultaneously provide pristine frequency spacings for precision metrology and the fundamental basis for ultrafast and attosecond sciences. Recently, nonlinear parametric conversion in high-Q microresonators has been suggested as an alternative platform for optical frequency combs, though almost all in 100 GHz frequencies or more. Here we report a low-phase-noise on-chip Kerr frequency comb with mode spacing compatible with high-speed silicon optoelectronics. The waveguide cross-section of the silicon nitride spiral resonator is designed to possess small and flattened group velocity dispersion, so that the Kerr frequency comb contains a record-high number of 3,600 phase-locked comb lines. We study the single-sideband phase noise as well as the long-term frequency stability and report the lowest phase noise floor achieved to date with -130 dBc/Hz at 1 MHz offset for the 18 GHz Kerr comb oscillator, along with feedback stabilization to achieve frequency Alla...
Vanin, Evgeny; Jacobsen, Gunnar
2010-03-01
The Bit-Error-Ratio (BER) floor caused by the laser phase noise in the optical fiber communication system with differential quadrature phase shift keying (DQPSK) and coherent detection followed by digital signal processing (DSP) is analytically evaluated. An in-phase and quadrature (I&Q) receiver with a carrier phase recovery using DSP is considered. The carrier phase recovery is based on a phase estimation of a finite sum (block) of the signal samples raised to the power of four and the phase unwrapping at transitions between blocks. It is demonstrated that errors generated at block transitions cause the dominating contribution to the system BER floor when the impact of the additive noise is negligibly small in comparison with the effect of the laser phase noise. Even the BER floor in the case when the phase unwrapping is omitted is analytically derived and applied to emphasize the crucial importance of this signal processing operation. The analytical results are verified by full Monte Carlo simulations. The BER for another type of DQPSK receiver operation, which is based on differential phase detection, is also obtained in the analytical form using the principle of conditional probability. The principle of conditional probability is justified in the case of differential phase detection due to statistical independency of the laser phase noise induced signal phase error and the additive noise contributions. Based on the achieved analytical results the laser linewidth tolerance is calculated for different system cases.
Mizan, Muhammad; Higgins, Thomas; Sturzebecher, Dana
1993-01-01
EPSD has designed, fabricated and tested, ultra-stable, low phase noise microwave dielectric resonator oscillators (DRO's) at S, X, Ku, and K-bands, for potential application to high dynamic range and low radar cross section target detection radar systems. The phase noise and the temperature stability surpass commercially available DROs. Low phase noise signals are critical for CW Doppler radars, at both very close-in and large offset frequencies from the carrier. The oscillators were built without any temperature compensation techniques and exhibited a temperature stability of 25 parts per million (ppm) over an extended temperature range. The oscillators are lightweight, small and low cost compared to BAW & SAW oscillators, and can impact commercial systems such as telecommunications, built-in-test equipment, cellular phone and satellite communications systems. The key to obtaining this performance was a high Q factor resonant structure (RS) and careful circuit design techniques. The high Q RS consists of a dielectric resonator (DR) supported by a low loss spacer inside a metal cavity. The S and the X-band resonant structures demonstrated loaded Q values of 20,300 and 12,700, respectively.
Turbulent phase noise on asymmetric two-way ground-satellite coherent optical links
Robert, Clélia; Conan, Jean-Marc; Wolf, Peter
2015-10-01
Bidirectional ground-satellite laser links suffer from turbulence-induced scintillation and phase distortion. We study how turbulence impacts on coherent detection capacity and on the associated phase noise that restricts clock transfer precision. We evaluate the capacity to obtain a two-way cancellation of atmospheric effects despite the asymmetry between up and down link that limits the link reciprocity. For ground-satellite links, the asymmetry is induced by point-ahead angle and possibly the use, for the ground terminal, of different transceiver diameters, in reception and emission. The quantitative analysis is obtained thanks to refined end-to-end simulations under realistic turbulence and wind conditions as well as satellite cinematic. Simulations make use of the reciprocity principle to estimate both down and up link performance from wave-optics propagation of descending plane waves. These temporally resolved simulations allow characterising the coherent detection in terms of time series of heterodyne efficiency for different system parameters. We show Tip/Tilt correction on ground is mandatory at reception for the down link and as a pre-compensation of the up link. Good correlation between up and down phase noise is obtained even with asymmetric apertures of the ground transceiver and in spite of pointing ahead angle. The reduction to less than 1 rad2 of the two-way differential phase noise is very promising for clock transfer.
A time-variant analysis of the 1/f^(2) phase noise in CMOS parallel LC-Tank quadrature oscillators
Andreani, Pietro
2006-01-01
This paper presents a study of 1/f2 phase noise in quadrature oscillators built by connecting two differential LC-tank oscillators in a parallel fashion. The analysis clearly demonstrates the necessity of adopting a time-variant theory of phase noise, where a more simplistic, time......-invariant approach fails to explain numerical simulation results even at the qualitative level. Two topologies of 5-GHz parallel quadrature oscillators are considered, and compact but nevertheless highly general, closed-form formulas are derived for the phase noise caused by the losses in the LC...
Song, Insang; Kim, Chungwoo; Kwon, Youngwoo; Cheon, Changyul; Song, Cimoo
1999-06-01
We introduce a new structure of the micromachined cavity resonator coupled GaAs-based oscillator to enhance the phase noise and the frequency stability. The oscillator and the cavity are designed for Ka-band applications. Compared to the free running oscillator, the cavity resonator coupled oscillator showed the phase noise enhancement of about 20 dB. The phase noises of about -110 and -85 dBc/Hz are obtained at 1 MHz and 100 kHz offset frequency, respectively. The frequency pushing for the gate bias of the cavity coupled oscillator is about two order of magnitude less than that of the free running oscillator.
Fard, A.; Andreani, Pietro
2007-01-01
This work presents an analysis of phase noise in the $1/f^{2}$ region displayed by both single-ended and differential bipolar Colpitts oscillators. Very accurate and rigorous symbolic phase noise expressions are derived, enabling a deeper insight into the major mechanisms of phase noise generation......, and providing new tools for design optimization. Phase noise expressions for the cross-coupled differential-pair LC-tank oscillator are derived as well....
Residual stress measurement in a metal microdevice by micro Raman spectroscopy
Song, Chang; Du, Liqun; Qi, Leijie; Li, Yu; Li, Xiaojun; Li, Yuanqi
2017-10-01
Large residual stress induced during the electroforming process cannot be ignored to fabricate reliable metal microdevices. Accurate measurement is the basis for studying the residual stress. Influenced by the topological feature size of micron scale in the metal microdevice, residual stress in it can hardly be measured by common methods. In this manuscript, a methodology is proposed to measure the residual stress in the metal microdevice using micro Raman spectroscopy (MRS). To estimate the residual stress in metal materials, micron sized β-SiC particles were mixed in the electroforming solution for codeposition. First, the calculated expression relating the Raman shifts to the induced biaxial stress for β-SiC was derived based on the theory of phonon deformation potentials and Hooke’s law. Corresponding micro electroforming experiments were performed and the residual stress in Ni–SiC composite layer was both measured by x-ray diffraction (XRD) and MRS methods. Then, the validity of the MRS measurements was verified by comparing with the residual stress measured by XRD method. The reliability of the MRS method was further validated by the statistical student’s t-test. The MRS measurements were found to have no systematic error in comparison with the XRD measurements, which confirm that the residual stresses measured by the MRS method are reliable. Besides that, the MRS method, by which the residual stress in a micro inertial switch was measured, has been confirmed to be a convincing experiment tool for estimating the residual stress in metal microdevice with micron order topological feature size.
Andrade, Luiz A [Divisao de Materiais, Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP 12201-970 (Brazil); Costa, Cesar A [Divisao de Astrofisica, Instituto Nacional de Pesquisas Espaciais, CP 515, Sao Jose dos Campos, SP 12201-970 (Brazil); Aguiar, Odylio D [Divisao de Astrofisica, Instituto Nacional de Pesquisas Espaciais, CP 515, Sao Jose dos Campos, SP 12201-970 (Brazil); Frajuca, Carlos [Centro Federal de Educacao Tecnologica de Sao Paulo, Rua Pedro Vicente 625, SP 01109-010 (Brazil); Mosso, Marbey M [CETUC, Centro de Estudos em Telecomunicacoes, PUC-RJ, Rio de Janeiro, RJ (Brazil); Podcameni, Abelardo [CETUC, Centro de Estudos em Telecomunicacoes, PUC-RJ, Rio de Janeiro, RJ (Brazil); Silva, Henrique J P P da [CETUC, Centro de Estudos em Telecomunicacoes, PUC-RJ, Rio de Janeiro, RJ (Brazil); Magalhaes, Nadja S [Instituto Tecnologica de Aeronautica, Departamento de FIsica, Praca Marechal Eduardo Gomes, 50, Sao Jose dos Campos, SP 12228-900 (Brazil)
2004-03-07
We developed a 10 GHz feedback oscillator with ultra-low phase noise. The oscillator was constructed to operate as the pump for the parametric transducers of the Mario Schenberg gravitational wave detector. We calculated the performance of the detector with this pump oscillator and determined how much improvement in phase noise would be necessary in order to reach the standard quantum limit in sensitivity.
A Phase Noise Analysis Method for Millimeter-Wave Passive Imager BHU-2D-U Frequency Synthesizer
Jin Zhang; Cheng Zheng; Xianxun Yao; Baohua Yang
2013-01-01
A nontrivial phase noise analysis method is proposed for frequency synthesizer of a passive millimeter-wave synthetic aperture interferometric radiometer (SAIR) imager for concealed weapon detections on human bodies with high imaging rates. The frequency synthesizer provides local oscillator signals for both millimeter-wave front ends and intermediate frequency IQ demodulators for the SAIR system. The influence of synthesizer phase noise in different offset frequency ranges on the visibility ...
Measurement of the residual stress in hot rolled strip using strain gauge method
Kumar, Lokendra; Majumdar, Shrabani; Sahu, Raj Kumar
2017-07-01
Measurement of the surface residual stress in a flat hot rolled steel strip using strain gauge method is considered in this paper. Residual stresses arise in the flat strips when the shear cut and laser cut is applied. Bending, twisting, central buckled and edge waviness is the common defects occur during the cutting and uncoiling process. These defects arise due to the non-uniform elastic-plastic deformation, phase transformation occurring during cooling and coiling-uncoiling process. The residual stress analysis is very important because with early detection it is possible to prevent an object from failure. The goal of this paper is to measure the surface residual stress in flat hot rolled strip using strain gauge method. The residual stress was measured in the head and tail end of hot rolled strip considering as a critical part of the strip.
Ishizawa, A; Nishikawa, T; Goto, T; Hitachi, K; Sogawa, T; Gotoh, H
2016-05-17
Low-noise millimetre-wave signals are valuable for digital sampling systems, arbitrary waveform generation for ultra-wideband communications, and coherent radar systems. However, the phase noise of widely used conventional signal generators (SGs) will increase as the millimetre-wave frequency increases. Our goal has been to improve commercially available SGs so that they provide a low-phase-noise millimetre-wave signal with assistance from an electro-optics-modulator-based optical frequency comb (EOM-OFC). Here, we show that the phase noise can be greatly reduced by bridging the vast frequency difference between the gigahertz and terahertz ranges with an EOM-OFC. The EOM-OFC serves as a liaison that magnifies the phase noise of the SG. With the EOM-OFC used as a phase noise "booster" for a millimetre-wave signal, the phase noise of widely used SGs can be reduced at an arbitrary frequency f (6 ≦ f ≦ 72 GHz).
Stefan Berger
2010-01-01
Full Text Available Channel estimation protocols for wireless two-hop networks with amplify-and-forward (AF relays are compared. We consider multiuser relaying networks, where the gain factors are chosen such that the signals from all relays add up coherently at the destinations. While the destinations require channel knowledge in order to decode, our focus lies on the channel estimates that are used to calculate the relay gains. Since knowledge of the compound two-hop channels is generally not sufficient to do this, the protocols considered here measure all single-hop coefficients in the network. We start from the observation that the direction in which the channels are measured determines (1 the number of channel uses required to estimate all coefficient and (2 the need for global carrier phase reference. Four protocols are identified that differ in the direction in which the first-hop and the second-hop channels are measured. We derive a sensible measure for the accuracy of the channel estimates in the presence of additive noise and phase noise and compare the protocols based on this measure. Finally, we provide a quantitative performance comparison for a simple single-user application example. It is important to note that the results can be used to compare the channel estimation protocols for any two-hop network configuration and gain allocation scheme.
Zhao, Weichen; Sun, Zhuo; Kong, Song
2016-10-01
Wireless devices can be identified by the fingerprint extracted from the signal transmitted, which is useful in wireless communication security and other fields. This paper presents a method that extracts fingerprint based on phase noise of signal and multiple level wavelet decomposition. The phase of signal will be extracted first and then decomposed by multiple level wavelet decomposition. The statistic value of each wavelet coefficient vector is utilized for constructing fingerprint. Besides, the relationship between wavelet decomposition level and recognition accuracy is simulated. And advertised decomposition level is revealed as well. Compared with previous methods, our method is simpler and the accuracy of recognition remains high when Signal Noise Ratio (SNR) is low.
A Method to Eliminate Effect of Phase Noise in OFDM Synchronization System
无
1999-01-01
OFDM (the orthogonal frequency division multiplexing) and its variety DMT (the discrete multitone) as delegates of the multicarrier modulation technology have given a big impact on the conventional data communication applications. Based on the theoretic a analysis of the OFDM technology, the impact of phase noise that introduced by the bit and symbol timing mechanism is discussed. Then a pilot correction and the cyclic prefix protection method are put forwarded to deal with the problem. These methods have been used in our experimental OFDM cable modem system to cope with the impulse noise and narrow band interference in the HFC (hybrid fiber and coax) upstream channel.
OTRA based second and third order sinusoidal oscillators and their phase noise performance
Komanapalli, Gurumurthy; Pandey, Neeta; Pandey, Rajeshwari
2017-07-01
In this paper operational transresistance amplifier (OTRA) based second and third order sinusoidal oscillators are proposed. The proposed second order oscillator is designed using single OTRA based Sallen Key low pass filter structure and third order oscillator is obtained by cascading three low pass filters and placing in a loop. The non-ideality and phase noise analyses of the circuits are also presented with necessary mathematical formulations. Workability of the proposed oscillators are verified through PSPICE simulations using 0.18µm AGILENT CMOS process parameters. The total harmonic distortion (THD) for proposed second order and third order oscillators are found as 3.27% and 0.631% respectively.
Dick, G. J.; Saunders, J.
1989-01-01
Oscillator configurations which reduce the effect of 1/f noise sources for both direct feedback and stabilized local oscillator (STALO) circuits are developed and analyzed. By appropriate use of carrier suppression, a small signal is generated which suffers no loss of loop phase information or signal-to-noise ratio. This small signal can be amplified without degradation by multiplicative amplifier noise, and can be detected without saturation of the detector. Together with recent advances in microwave resonator Qs, these circuit improvements will make possible lower phase noise than can be presently achieved without the use of cryogenic devices.
Phase noise analysis of clock recovery based on an optoelectronic phase-locked loop
Zibar, Darko; Mørk, Jesper; Oxenløwe, Leif Katsuo
2007-01-01
A detailed theoretical analysis of a clock-recovery (CR) scheme based on an optoelectronic phase-locked loop is presented. The analysis emphasizes the phase noise performance, taking into account the noise of the input data signal, the local voltage-controlled oscillator (VCO), and the laser....... It is shown that a large loop length results in a higher timing jitter of the recovered clock signal. The impact of the loop length on the clock signal jitter can be reduced by using a low-noise VCO and a low loop filter bandwidth. Using the model, the timing jitter of the recovered optical and electrical...
Phase noise from aircraft motion: Compensation and effect on synthetic aperture radar images
Gabriel, Andrew K.; Goldstein, Richard M.
1986-01-01
Image degradation of airborne SAR imagery caused by phase errors introduced in the received signal by aircraft motion is discussed. Mechanical motion has a small bandwidth and does not affect the range signal, where the total echo time is typically 60 microsec. However, since the aperture length can be several seconds, the synthesized azimuth signal can have significant errors of which phase noise is the most important. An inertial navigation system can be used to compensate for these errors when processing the images. Calculations to evaluate how much improvement results from compensation are outlined.
The role of amplitude-to-phase conversion in the generation of oscillator flicker phase noise
Hearn, C. P.
1985-01-01
The role of amplitude-to-phase conversion as a factor in feedback oscillator flicker phase noise is examined. A limiting stage consisting of parallel-connected opposite polarity diodes operating in a circuit environment contining reactance is shown to exhibit amplitude-to-phase conversion. This mechanism coupled with resistive upconversion provides an indirect route for very low frequency flicker noise to be transferred into the phase of an oscillator signal. It is concluded that this effect is more significant in the lower frequency regimes where the onlinear reactances associated with active devices are overwhelmed by linear reactive elements.
Magnard, C.; Small, D.; Meier, E.
2015-03-01
The phase estimation of cross-track multibaseline synthetic aperture interferometric data is usually thought to be very efficiently achieved using the maximum likelihood (ML) method. The suitability of this method is investigated here as applied to airborne single pass multibaseline data. Experimental interferometric data acquired with a Ka-band sensor were processed using (a) a ML method that fuses the complex data from all receivers and (b) a coarse-to-fine method that only uses the intermediate baselines to unwrap the phase values from the longest baseline. The phase noise was analyzed for both methods: in most cases, a small improvement was found when the ML method was used.
Measuring residual stress in ceramic zirconia-porcelain dental crowns by nanoindentation.
Zhang, Y; Allahkarami, M; Hanan, J C
2012-02-01
Residual stress plays a critical role in failure of ceramic dental crowns. The magnitude and distribution of residual stress in the crown system are largely unknown. Determining the residual stress quantitatively is challenging since the crown has such complex contours and shapes. This work explored the feasibility and validity of measuring residual stress of zirconia and porcelain in ceramic crowns by nanoindentation. Nanoindentation tests were performed on the cross-section of a crown for both porcelain and zirconia along four critical locations: the thickest, thinnest and medium porcelain thicknesses. Zirconia and porcelain pieces, chipped off from the crown and annealed at 400 °C, were used as reference samples. The residual stress was determined by comparing the measured hardness of the stressed sample with that of the reference sample. Nanoindentation impression images were acquired through a scanning probe microscope (SPM) equipped with a Hysitron Triboindenter. Zirconia showed large pile-up. Residual stress is determined along the thickness of crowns at the chosen locations for both porcelain and zirconia. The measured results were compared with the results from X-ray diffraction (XRD) and finite element modeling (FEM). Results show there are large amounts of residual stresses in the dental crown and their magnitude differs between locations due to the complex shape of the crown. The average residual stress readings were as high as -637 MPa and 323 MPa for zirconia and porcelain respectively.
Drinking water ozone disinfection systems measure ozone residual concentration, C, for regulatory compliance reporting of concentration-times-time (CT), and the resultant log-inactivation of virus, Giardia and Cryptosporidium. The indigotrisulfonate (ITS) colorimetric procedure i...
On the reliability of neutron diffraction for residual stress measurement in cold-drawn steels
Ruiz-Hervias, J.; Mompean, F.; Hofmann, M.; Atienza, J. M.
2011-10-01
Residual strains were measured in the ferrite phase of pearlitic steel rods along the radial, axial and hoop directions. Two samples with different initial diameters were subjected to one drawing pass (using same drawing parameters) with 20% section reduction and measured in two different neutron diffraction instruments. The results show that the residual strain state is very similar in both cases, regardless of the diameter of the initial rod. This means that the final residual strain-stress state is unique and it is related to the cold-drawing process parameters. In addition, the results show the reliability of strain scanning with different neutron instruments and experimental conditions.
Dimensioning BCH codes for coherent DQPSK systems with laser phase noise and cycle slips
Leong, Miu Yoong; Larsen, Knud J.; Jacobsen, Gunnar
2014-01-01
Forward error correction (FEC) plays a vital role in coherent optical systems employing multi-level modulation. However, much of coding theory assumes that additive white Gaussian noise (AWGN) is dominant, whereas coherent optical systems have significant phase noise (PN) in addition to AWGN. Thi...... approach for a target post-FEC BER of 10-5. Codes dimensioned with our bivariate binomial model meet the target within 0.2-dB signal-to-noise ratio....... these statistics to parameterize a bivariate binomial model that describes the distribution of bit errors. In this way, we relate pre-FEC statistics to post-FEC BER and BCH codes. Our method is applicable to pre-FEC BER around 10-3 and any post-FEC BER. Using numerical simulations, we evaluate the accuracy of our......Forward error correction (FEC) plays a vital role in coherent optical systems employing multi-level modulation. However, much of coding theory assumes that additive white Gaussian noise (AWGN) is dominant, whereas coherent optical systems have significant phase noise (PN) in addition to AWGN...
Residual oil aerosol measurements on refrigerators and liquefiers
Pflueckhahn, D.; Anders, W.; Hellwig, A.; Knobloch, J.; Rotterdam, S.
2014-01-01
The purity of the process gas is essential for the reliability of refrigerators and liquefiers. Filtration and adsorption of impurities like water, nitrogen, and oil result in a major effort, cost, and maintenance in the helium process. Expensive impurity monitors for moisture, nitrogen, and hydrocarbon contents are required to identify filter failures and leakage immediately during the operation. While water and nitrogen contaminants can be detected reliably, the measurement of oil aerosols at the ppb-level is challenging. We present a novel diagnostic oil aerosol measurement system able to measure particles in the sub-μm range. This unit enabled us to evaluate and improve the oil separation system on a LINDE TCF 50 helium liquefier.
Chen, Yu; Zou, Jian; Yang, Zi-Yi; Li, Longwu; Li, Hai; Shao, Bin
2016-08-01
The dynamics of N-qubit GHZ state quantum Fisher information (QFI) under phase noise lasers (PNLs) driving is investigated in terms of non-Markovian master equation. We first investigate the non-Markovian dynamics of the QFI of N-qubit GHZ state and show that when the ratio of the PNL rate and the system-environment coupling strength is very small, the oscillations of the QFIs decay slower which corresponds to the non-Markovian region; yet when it becomes large, the QFIs monotonously decay which corresponds to the Markovian region. When the atom number N increases, QFIs in both regions decay faster. We further find that the QFI flow disappears suddenly followed by a sudden birth depending on the ratio of the PNL rate and the system-environment coupling strength and the atom number N, which unveil a fundamental connection between the non-Markovian behaviors and the parameters of system-environment couplings. We discuss two optimal positive operator-valued measures (POVMs) for two different strategies of our model and find the condition of the optimal measurement. At last, we consider the QFI of two atoms with qubit-qubit interaction under random telegraph noises (RTNs).
More on the 1/f(2) phase noise performance of CMOS differential-pair LC-tank oscillators
Andreani, Pietro; Fard, Ali
2006-01-01
This paper presents a rigorous phase noise analysis in the 1/f2 region for the differential CMOS LC-tank oscillator with both nMOS and pMOS switch pairs. A compact, closed-form phase noise equation is obtained, accounting for the noise contributions from both tank losses and transistors currents......, which allows a robust comparison between LC oscillators built with either one or two switch pairs. The fabricated oscillator prototype is tunable between 2.15 and 2.35 GHz, and shows a phase noise of -144 dBc/Hz at 3 MHz offset from the 2.3 GHz carrier for a 4 mA bias current. The phase noise figure......-of-merit is practically constant across the tuning range, with a minimum of 191.5 dBc/Hz. A reference single-switch-pair oscillator has been implemented and tested as well, and the difference between the phase noise levels displayed by the two oscillators is very nearly the one expected from theory...
Svendsen, Jesper Hastrup; Paaske, W P; Haunsø, S
1991-01-01
In previous studies the tissue injection, residue detection method failed to provide results of diffusional capillary permeability comparable to those of other methods. For this reason we reconsidered the kinetic theory and found that it is necessary to take into account the apparent (restricted...... detection method and the single injection, residue detection method. Blood flow was measured independently with local 133Xenon washout. D and D' were measured by a true transient diffusion method. We found that the tissue injection, residue detection method gave results for capillary extraction and Pd......S-product similar to those obtained with a number of other methods based on indicator diffusion, so the tissue injection, residue detection method in its new kinetically correct formulation could prove useful in clinical studies of capillary permeability since it is applicable to determination of relative changes...
Laser Treatment of HVOF Coating: Modeling and Measurement of Residual Stress in Coating
Arif, A. F. M.; Yilbas, B. S.
2008-10-01
High-velocity oxy-fuel (HVOF) coating of diamalloy 1005 (similar to Inconel 625 alloy) onto the Ti-6Al-4V alloy is considered and laser-controlled melting of the coating is examined. The residual stress developed after the laser treatment process is modeled using the finite element method (FEM). The experiment is conducted to melt the coating using a laser beam. The residual stress measurement in the coating after the laser treatment process is realized using the XRD technique. The morphological and metallurgical changes in the coating are examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It is found that the residual stress reduces at the coating-base material interface and the residual stress predicted agrees with the XRD measurements. A compact and crack-free coating is resulted after the laser treatment process.
Design of the Low Phase Noise VCO%低相位噪声VCO的设计
向永波; 阎跃鹏; 高海飞
2012-01-01
A low phase noise phase voltage controlled oscillator (VCO) for mobile communication repeater station was designed. Colpitts structure was adopted for the VCO, LC components was used as the resonator and BJT was used as the amplifier component. The frequency tuning range is from 730 MHz to 840 MHz with the output power of 10.7 dBm and the pressure control sensitivity of 22 MHz/V. At 800 MHz central frequency, the phase noise is -99. 42 dBc/Hz at 10 kHz offset, - 116. 44 dBc/Hz at 100 kHz offset and - 135. 06 dBc/Hz at 1 MHz offset separately. A low frequency filtering method at the base electrode was proposed to eliminate the spur, and no obvious spur was observed within the full test frequency band. The major phase noise source of the VCO was summarized, and the design method for the low noise VCO was given. The calculation result, simulation result and test result match well, which provides some references for the design of the low noise VCO.%设计了一个用于移动通信中继站的低相位噪声压控振荡器(VCO).该VCO采用了考皮兹结构,谐振器使用LC器件,放大器件使用双极结型晶体管(BJT).其频率调动范围为730～840MHz,压控灵敏度为22MHz/V,输出功率为10.7 dBm.在800MHz中心频率处,其实测相位噪声分别为-99.42dBc/Hz@10kHz,-116.44 dBc/Hz@100kHz,-135.06dBc/Hz@1 MHz.提出了一种采用基极低频滤波的办法消除VCO的杂散频率,整个测试频段内观察不到明显的杂散.阐述了VCO相位噪声的主要来源,给出了低噪声VCO的设计方法.理论计算,仿真结果和实物测试取得了一致的结论,对低噪声VCO的设计提供了一定的参考.
De, Syamsundar; Baili, Ghaya; Bouchoule, Sophie; Alouini, Mehdi; Bretenaker, Fabien
2015-05-01
The amplitude and phase noises of a dual-frequency vertical-external-cavity surface-emitting laser (DF-VECSEL) operating at telecom wavelength are theoretically and experimentally investigated in detail. In particular, the spectral behavior of the correlation between the intensity noises of the two modes of the DF-VECSEL is measured. Moreover, the correlation between the phase noise of the radio-frequency beat note generated by optical mixing of the two laser modes with the intensity noises of the two modes is investigated. All these spectral behaviors of noise correlations are analyzed for two different values of the nonlinear coupling between the laser modes. We find that to describe the spectral behavior of noise correlations between the laser modes, it is of utmost importance to have precise knowledge about the spectral behavior of the pump noise, which is the dominant source of noise in the frequency range of interest (10 kHz to 35 MHz). Moreover, it is found that the noise correlation also depends on how the spatially separated laser modes of the DF-VECSEL intercept the noise from a multimode fiber-coupled laser diode used for pumping both the laser modes. To this aim, a specific experiment is reported which aims at measuring the correlations between different spatial regions of the pump beam. The experimental results are in excellent agreement with a theoretical model based on modified rate equations.
Yishu, Jiao; Yumei, Zhou; Jianhua, Jiang; Bin, Wu
2010-09-01
This paper describes the design of a fully integrated low phase noise CMOS phase-locked loop for mixed-signal SoCs with a wide range of operating frequencies. The design proposes a multi-regulator PLL architecture, in which every noise-sensitive block from the PLL top level is biased from a dedicated linear or shunt regulator, reducing the parasitic noise and spur coupling between different PLL building blocks. Supply-induced VCO frequency sensitivity of the PLL is less than 0.07%-fvco/1%-VDD. The design is fabricated in 0.13 μm 1.5/3.3 V CMOS technology. The in-band phase noise of -102 dBc/Hz at 1 MHz offset with a spur of less than -45 dBc is measured from 1.25 GHz carrier. The measured RMS jitter of the proposed PLL is 1.72 ps at a 1.25 GHz operating frequency. The total power consumption is 19 mW, and its active area is 0.19 mm2.
Effects of laser phase noise on the performance of optical coherent receivers
LIU Ji-hong; LI Zhao-lin; LIANG Meng
2012-01-01
Laser phase noise (LPN) plays an important role in optical coherent systems.Based on the algorithm of Viterbi-Viterbi carrier phase estimation (CPE),the effects of LPN imposed on the coherent receivers are investigated for quadrature phase shift keying (QPSK),8 phase shift keying (8PSK) and 16-quadrature amplitude modulation (16-QAM) optical coherent systems,respectively.The simulation results show that the optimal block length in the phase estimation algorithm is a tradeoff between LPN and additive white Gaussian noise (AWGN),and depends on the level of modulation formats.The resolution requirements of analog to digital converter (ADC) in the coherent receivers are independent of LPN or the level of modulation formats.For the bit error rate (BER) of 10-3,the required bit number of ADC is 6,and the gain is marginal for the higher resolution.
Arnaud, N.; Balembois, L.; Bizouard, M. A.; Brisson, V.; Casanueva, J.; Cavalier, F.; Davier, M.; Frey, V.; Hello, P.; Huet, D.; Leroy, N.; Loriette, V.; Maksimovic, I.; Robinet, F.
2017-02-01
The second generation of Gravitational waves detectors are kilometric Michelson interferometers with additional recycling Fabry-Perot cavities on the arms and the addition of two more recycling cavities to enhance their sensitivity, with the particularity that all the mirrors are suspended. In order to control them a new technique, based on the use of auxiliary lasers, has been developed to bring the interferometer to its working point, with all the cavities on their resonance, in an adiabatic way. The implementation of this technique in Advanced Virgo is under preparation and the propagation of a stable laser through a 3-km optical fibre is one of the most problematic issues. A new technique of active phase noise cancellation based on the use of Electro Optical Modulators has been developed, and a first prototype has been successfully tested.
Dynamical responses in a new neuron model subjected to electromagnetic induction and phase noise
Wu, Fuqiang; Wang, Chunni; Jin, Wuyin; Ma, Jun
2017-03-01
Complex electrical activities in neuron can induce time-varying electromagnetic field and the effect of various electromagnetic inductions should be considered in dealing with electrical activities of neuron. Based on an improved neuron model, the effect of electromagnetic induction is described by using magnetic flux, and the modulation of magnetic flux on membrane potential is realized by using memristor coupling. Furthermore, additive phase noise is imposed on the neuron to detect the dynamical response of neuron and phase transition in modes. The dynamical properties of electrical activities are detected and discussed, and double coherence resonance behavior is observed, respectively. Furthermore, multiple modes of electrical activities can be observed in the sampled time series for membrane potential of the neuron model.
Nonlinear phase noise mitigation in phase-sensitive amplified transmission systems.
Olsson, Samuel L I; Karlsson, Magnus; Andrekson, Peter A
2015-05-04
We investigate the impact of in-line amplifier noise in transmission systems amplified by two-mode phase-sensitive amplifiers (PSAs) and present the first experimental demonstration of nonlinear phase noise (NLPN) mitigation in a modulation format independent PSA-amplified transmission system. The NLPN mitigation capability is attributed to the correlated noise on the signal and idler waves at the input of the transmission span. We study a single-span system with noise loading in the transmitter but the results are expected to be applicable also in multi-span systems. The experimental investigation is supported by numerical simulations showing excellent agreement with the experiments. In addition to demonstrating NLPN mitigation we also present a record high sensitivity receiver, enabled by low-noise PSA-amplification, requiring only 4.1 photons per bit to obtain a bit error ratio (BER) of 1 × 10(-3) with 10 GBd quadrature phase-shift keying (QPSK) data.
Experimental demonstration of a dual-frequency laser free from anti-phase noise
Amili, Abdelkrim El; De, Syamsundar; Schwartz, Sylvain; Feugnet, Gilles; Pocholle, Jean-Paul; Bretenaker, Fabien; Alouini, Mehdi
2012-01-01
A reduction of more than 20 dB of the intensity noise at the anti-phase relaxation oscillation frequency is experimentally demonstrated in a two-polarization dual-frequency solid-state laser without any optical or electronic feedback loop. Such a behavior is inherently obtained by aligning the two orthogonally polarized oscillating modes with the crystallographic axes of a (100)-cut neodymium-doped yttrium aluminum garnet active medium. The anti-phase noise level is shown to increase as soon as one departs from this peculiar configuration, evidencing the predominant role of the nonlinear coupling constant. This experimental demonstration opens new perspectives on the design and realization of extremely low noise dual-frequency solid-state lasers.
V. N. Senthil Kumaran
2013-01-01
Full Text Available In this study, the performance of OFDM based bidirectional relay network which employs Physical Layer Network Coding (PLNC is analyzed in the presence of phase noise. The bidirectional relay network is assumed to consist of two sources and a relay, where each node has a single antenna and operates in half duplex mode. The PLNC based OFDM system transmits high data streams over numerous sub channels in frequency domain. Each sub channel is a narrow band flat fading channel, thereby achieving high spectral efficiency over wide band channels. In practice, phase noise is introduced with the information symbols transmitted on all subcarriers in OFDM transceiver. The influence of phase noise on the received signals are analyzed at both the Multiple Access Channel (MAC and at the Broadcast Channel (BC environments.
Measurement of the residual energy of muons in the Gran Sasso underground Laboratories
Ambrosio, M; Baldini, A; Barbarino, G C; Barish, B C; Battistoni, G; Becherini, Y; Bellotti, R; Bemporad, C; Bernardini, P; Bilokon, H; Bower, C; Brigida, M; Bussino, S; Cafagna, F; Calicchio, M; Campana, D; Carboni, M; Caruso, R; Cecchini, S; Cei, F; Chiarella, V; Choudhary, B C; Coutu, S; Cozzi, M; De Cataldo, G; De Marzo, C; De Mitri, I; De Vincenzi, M; Dekhissi, H; Derkaoui, J; Di Credico, A; Erriquez, O; Favuzzi, C; Forti, C; Fusco, P; Giacomelli, G; Giannini, G; Giglietto, N; Giorgini, M; Grassi, M; Grillo, A A; Guarino, F; Gustavino, C; Habig, A; Hanson, K; Heinz, R; Iarocci, E; Katsavounidis, E; Katsavounidis, I; Kearns, E; Kim, H J; Kyriazopoulou, S; Lamanna, E; Lane, C; Levin, D S; Lipari, P; Longley, N P; Longo, M J; Loparco, F; Mancarella, G; Mandrioli, G; Margiotta, A; Marini, A; Martello, D; Marzari-Chiesa, A; Mazziotta, M N; Michael, D G; Monacelli, P; Montaruli, T; Monteno, M; Mufson, S; Musser, J; Nicolò, D; Nolty, R; Orth, C; Osteria, G; Palamara, O; Patera, V; Patrizii, L; Pazzi, R; Peck, C W; Perrone, L; Petrera, S; Pistilli, P; Popa, V; Rainó, A; Reynoldson, J; Ronga, F; Satriano, C; Scapparone, E; Scholberg, K; Sciubba, A; Serra, P; Sioli, M; Sirri, G; Sitta, M; Spinelli, P; Spinetti, M; Spurio, M; Steinberg, R; Stone, J L; Sulak, L R; Surdo, A; Tarle, G; Vakili, M; Walter, C W; Webb, R
2003-01-01
The MACRO detector was located in the Hall B of the Gran Sasso underground Laboratories under an average rock overburden of 3700 hg/cm^2. A transition radiation detector composed of three identical modules, covering a total horizontal area of 36 m^2, was installed inside the empty upper part of the detector in order to measure the residual energy of muons. This paper presents the measurement of the residual energy of single and double muons crossing the apparatus. Our data show that double muons are more energetic than single ones. This measurement is performed over a standard rock depth range from 3000 to 6500 hg/cm^2.
Quantum 1/f noise in GaN FETs, HFETs, MODFETs, and their oscillators' phase noise
Handel, Peter H.; Hall, Amanda M.; Morkoç, Hadis
2007-02-01
GaN-based FETs, HFETs and MODFETs are ideally suited for use in high-power amplifiers and oscillators, due to their large band gap and high operating voltages. According to the quantum 1/f theory, the larger effective mass implied for the carriers also leads to lower fundamental 1/f noise and to lower resulting phase noise close to the carrier frequency. We have therefore studied the quantum 1/f noise sources in the channel and in the gate insulation. For the channel, a combination of conventional and coherent Quantum 1/f Effect (Q1/fE) is present, with the conventional Q1/fE dominant in the sub-threshold part of the channel toward the drain. It turns out that the quantum 1/f parameter "s" that determines the fraction of the two forms of Q1/fE, is no longer increasing proportionally to the width of the device w, when the latter exceeds the length of the channel. A logarithmic dependence on w is obtained for s instead. This is why an extremely large width w does not automatically lead to coherent Q1/fE in HFETs. Conventional Q1/fE applies for the gate insulation, with contributions of the much larger piezoelectric Q1/fE in spontaneously polarized AlGaN, if gate leakage is present. The noise figure is calculated, including all contributions. Finally, the minimal expected oscillator phase noise is calculated from the Q1/fE in the dissipative elements, even for perfectly linear amplifiers, by multiplication with the inverse fourth power of the quality factor, as was first done by us for quartz in 1979.
Deng, Lei; Pang, Xiaodan; Zhang, Xu
2013-01-01
We report on the transmission of 8 Gb/s 0 dB PAPR 16QAM-OFDM W-band (75-110 GHz) signals over 22.8km SMF without phase noise compensation by using a phase modulator in the optical heterodyne up-convertor.......We report on the transmission of 8 Gb/s 0 dB PAPR 16QAM-OFDM W-band (75-110 GHz) signals over 22.8km SMF without phase noise compensation by using a phase modulator in the optical heterodyne up-convertor....
Synchrotron measurements of local microstructure and residual strains in ductile cast iron
Zhang, Y. B.; Andriollo, T.; Fæster, S.; Liu, W.; Sturlason, A.; Barabash, R.
2017-07-01
The local microstructure and distribution of thermally induced residual strains in ferrite matrix grains around an individual spherical graphite nodule in ductile cast iron (DCI) were measured using a synchrotron X-ray micro-diffraction technique. It is found that the matrix grains are deformed, containing dislocations and dislocation boundaries. Each of the residual strain components in the matrix grains exhibits a complex pattern along the circumferential direction of the nodule. Along the radial direction of the nodule, strain gradients from the interface to the grain interior are seen for some strain components, but only in some matrix grains. The observed residual strain patterns have been analysed by finite element modelling, and a comparison between the simulation and experiments is given. The present study of local residual stress by both experimental characterization and simulation provide much needed information for understanding the mechanical properties of DCI, and represent an important contribution for the microstructural design of new DCI materials.
X-ray residual stress measurement of laminated coating layers produced by plasma spraying
Nishida, Masayuki (Faculty of Engineering, Tokushima Univ. (Japan)); Hanabusa, Takao (Faculty of Engineering, Tokushima Univ. (Japan)); Fujiwara, Haruo (Faculty of Engineering, Tokushima Univ. (Japan))
1993-12-03
The present paper describes residual stress in laminated layers deposited by thermal spraying on a low carbon steel substrate. Laminated layers were made of Al[sub 2]O[sub 3]-NiCr or Al[sub 2]O[sub 3]-NiAl with various combinations of mixing ratios. X-Ray diffraction was used to measure residual stress in the outermost surface layer. The results of finite-element method (FEM) thermal stress analysis were compared with the experimental results of X-ray measurements. From the X-ray stress measurements, tensile residual stress (100-300 MPa) was measured in the as-coated surface layers of all specimens. The effect of annealing on residual stress variation was also examined. In the case of the Al[sub 2]O[sub 3] (100%) layer of the Al[sub 2]O[sub 3]-NiCr system, residual stress of surface layers was not greatly affected by the method of lamination and did not change significantly upon annealing. In contrast, in the layer with mixed Al[sub 2]O[sub 3] and NiAl, residual stress in the as-coated layer was influenced by the mixing ratio of Al[sub 2]O[sub 3] and NiAl. Furthermore, residual stresses were gradually reduced in both the Al[sub 2]O[sub 3] and Ni phase following annealing. FEM calculation revealed that large compressive residual stress (about -2 GPa) was produced in the 100% Al[sub 2]O[sub 3] layer after a full annealing treatment. The value of residual stress depends on the difference between the thermal expansion coefficients of the laminated layers and the substrate. This result was exactly opposite to the experimental results for the fully annealed Al[sub 2]O[sub 3]-NiCr system. However, residual stresses in the mixed layer (Al[sub 2]O[sub 3]-NiAl) depended on the mixing ration of Al[sub 2]O[sub 3] and NiAl. This agrees qualitatively with the experimental results. (orig.)
Measuring dry plant residues in grasslands: A case study using AVIRIS
Fitzgerald, Michael; Ustin, Susan L.
1992-01-01
Grasslands, savannah, and hardwood rangelands are critical ecosystems and sensitive to disturbance. Approximately 20 percent of the Earth's surface are grasslands and represent 3 million ha. in California alone. Developing a methodology for estimating disturbance and the effects of cumulative impacts on grasslands and rangelands is needed to effectively monitor these ecosystems. Estimating the dry biomass residue remaining on rangelands at the end of the growing season provides a basis for evaluating the effectiveness of land management practices. The residual biomass is indicative of the grazing pressure and provides a measure of the system capacity for nutrient cycling since it represents the maximum organic matter available for decomposition, and finally, provides a measure of the erosion potential for the ecosystem. Remote sensing presents a possible method for measuring dry residue. However, current satellites have had limited application due to the coarse spatial scales (relative to the patch dynamics) and insensitivity of the spectral coverage to resolve dry plant material. Several hypotheses for measuring the biochemical constituents of dry plant material, particularly cellulose and lignin, using high spectral resolution sensors were proposed. The use of Airborne Visible/Infrared Imaging Spectrometers (AVIRIS) to measure dry plant residues over an oak savannah on the eastern slopes of the Coast Range in central California was investigated and it was asked what spatial and spectral resolutions are needed to quantitatively measure dry plant biomass in this ecosystem.
Residual stress measurement on propellant tank of 2219 aluminum alloy and study on its weak spot
Huang, Chaoqun; Li, Huan; Li, Jianxiong; Luo, Chuanguang; Ni, Yanbing [Tianjin University, Tianjin (China)
2017-05-15
This paper presented residual stress measurement on two circumferential Variable polarity plasma arc welding (VPPAW) joints and one circular closed Friction stir welding (FSW) joint on the propellant tank of 2219 aluminum alloy using the indentation strain-gauge method. Quite large tensile residual stresses were attached to the center and inner areas of the circular closed FSW joint. There were very large tensile stresses in some points of the two circumferential VPPAW joints, among these points, the maximum value was +253 MPa, which was about 63 % of the yield strength of 410 MPa measured in the base material. In addition, the peak of compressive residual stress was about -160 MPa. Above all, there were two typical peaks of residual stress in the circumferential VPPAW joints, one was located in the middle part while the other one was near the start/end position of the joints. Combining the result of residual stress measurement with the characteristics of the tank structure, it can be concluded that circular closed FSW joint around the flange was a weak spot on the propellant tank. And the most vulnerable point on the circular closed FSW joint has also been found.
Measurement and modelling of residual stresses in straightened commercial eutectoid steel rods
Martinez-Perez, M.L. [ICMM, CSIC, Campus de Cantoblanco, E-28049 Madrid (Spain); Borlado, C.R. [ICMM, CSIC, Campus de Cantoblanco, E-28049 Madrid (Spain); Open University, Faculty of Technology, Milton Keynes, MK7 6AL (United Kingdom); Mompean, F.J. [ICMM, CSIC, Campus de Cantoblanco, E-28049 Madrid (Spain); Garcia-Hernandez, M. [ICMM, CSIC, Campus de Cantoblanco, E-28049 Madrid (Spain); Gil-Sevillano, J. [CEIT, Paseo de Manuel Lardizabal 15, E-20018 San Sebastian (Spain); Ruiz-Hervias, J. [Departamento de Ciencia de Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, c/ Profesor Aranguren s/n, E-28040 Madrid (Spain); Atienza, J.M. [Departamento de Ciencia de Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, c/ Profesor Aranguren s/n, E-28040 Madrid (Spain)]. E-mail: jmatienza@mater.upm.es; Elices, M. [Departamento de Ciencia de Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, c/ Profesor Aranguren s/n, E-28040 Madrid (Spain); Peng, Ru Lin [NFL Studsvik, Uppsala University, S-61182 Nykoeping (Sweden); Daymond, M.R. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, K7L 3N6 (Canada)
2005-09-15
Neutron strain scanning measurements on a eutectoid steel rod that has been subjected to standard industrial coiling and straightening operations are presented. Strains were determined non-destructively using two different diffractometers, one at a steady-state neutron source and the other at a pulsed spallation neutron source, with measurements made in both the ferrite and cementite components of the pearlitic microstructure. The residual stress state is explained in terms of a simplified analytical model for a two-phase material, which takes into account the successive loading operations contributing to residual stress. The results show that residual stresses generated by bending-straightening operations are significant and are likely to play an important role in the mechanical properties of the final wires.
Uncertainty Quantification and Comparison of Weld Residual Stress Measurements and Predictions.
Lewis, John R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brooks, Dusty Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-10-01
In pressurized water reactors, the prevention, detection, and repair of cracks within dissimilar metal welds is essential to ensure proper plant functionality and safety. Weld residual stresses, which are difficult to model and cannot be directly measured, contribute to the formation and growth of cracks due to primary water stress corrosion cracking. Additionally, the uncertainty in weld residual stress measurements and modeling predictions is not well understood, further complicating the prediction of crack evolution. The purpose of this document is to develop methodology to quantify the uncertainty associated with weld residual stress that can be applied to modeling predictions and experimental measurements. Ultimately, the results can be used to assess the current state of uncertainty and to build confidence in both modeling and experimental procedures. The methodology consists of statistically modeling the variation in the weld residual stress profiles using functional data analysis techniques. Uncertainty is quantified using statistical bounds (e.g. confidence and tolerance bounds) constructed with a semi-parametric bootstrap procedure. Such bounds describe the range in which quantities of interest, such as means, are expected to lie as evidenced by the data. The methodology is extended to provide direct comparisons between experimental measurements and modeling predictions by constructing statistical confidence bounds for the average difference between the two quantities. The statistical bounds on the average difference can be used to assess the level of agreement between measurements and predictions. The methodology is applied to experimental measurements of residual stress obtained using two strain relief measurement methods and predictions from seven finite element models developed by different organizations during a round robin study.
Performance analysis of an all-optical OFDM system in presence of non-linear phase noise.
Hmood, Jassim K; Harun, Sulaiman W; Emami, Siamak D; Khodaei, Amin; Noordin, Kamarul A; Ahmad, Harith; Shalaby, Hossam M H
2015-02-23
The potential for higher spectral efficiency has increased the interest in all-optical orthogonal frequency division multiplexing (OFDM) systems. However, the sensitivity of all-optical OFDM to fiber non-linearity, which causes nonlinear phase noise, is still a major concern. In this paper, an analytical model for estimating the phase noise due to self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in an all-optical OFDM system is presented. The phase noise versus power, distance, and number of subcarriers is evaluated by implementing the mathematical model using Matlab. In order to verify the results, an all-optical OFDM system, that uses coupler-based inverse fast Fourier transform/fast Fourier transform without any nonlinear compensation, is demonstrated by numerical simulation. The system employs 29 subcarriers; each subcarrier is modulated by a 4-QAM or 16-QAM format with a symbol rate of 25 Gsymbol/s. The results indicate that the phase variance due to FWM is dominant over those induced by either SPM or XPM. It is also shown that the minimum phase noise occurs at -3 dBm and -1 dBm for 4-QAM and 16-QAM, respectively. Finally, the error vector magnitude (EVM) versus subcarrier power and symbol rate is quantified using both simulation and the analytical model. It turns out that both EVM results are in good agreement with each other.
O. Baran
2010-12-01
Full Text Available Our work deals with studies of a noise behavior in space communication systems. Two most important noise types the additive thermal noise and the multiplicative phase noise, respectively, are included. A simple model of the narrowband communication system is created and simulated in the Ansoft Designer system simulator. The additive thermal noise is modeled as AWGN in a communication channel. The phase noise is produced in transmitter and receiver oscillators. The main intention is to investigate the receiver filter bandwidth decrease effect on powers of both noise types. Results proposed in this paper show that for defined system conditions and for a certain filter bandwidth value, the power of the multiplicative phase noise equals to the additive thermal noise power. Another decrease of the filter bandwidth causes the phase noise power exceeding. To demonstrate the noise behavior transparently, input system parameters are properly selected. All simulation results are documented by theoretical calculations. Simulation outcomes express a good coincidence with presumptions and calculations.
FAN JianXing; YANG HuaZhong; WANG Hui; YAN XiaoLang; HOU ChaoHuan
2007-01-01
Phase noise analysis of an oscillator is implemented with its periodic time-varying small signal state equations by perturbing the autonomous large signal state equations of the oscillator. In this paper, the time domain steady solutions of oscillators are perturbed with traditional regular method; the periodic time-varying Jocobian modulus matrices are decomposed with Sylvester theorem, and on the resulting space spanned by periodic vectors, the conditions under which the oscillator holds periodic steady states with any perturbations are analyzed. In this paper, stochastic calculus is applied to disclose the generation process of phase noise and calculate the phase jitter of the oscillator by injecting a pseudo sinusoidal signal in frequency domain, representing the white noise, and a δ correlation signal in time domain into the oscillator. Applying the principle of frequency modulation, we learned how the power-law and the Lorentzian spectrums are formed. Their relations and the Lorentzian spectrums of harmonics are also worked out. Based on the periodic Jacobian modulus matrix, the simple algorithms for Floquet exponents and phase noise are constructed, as well as a simple case is demonstrated. The analysis difficulties and the future directions for the phase noise of oscillators are also pointed out at the end.
Measurement and prediction of residual stress in a bead-on-plate weld benchmark specimen
Ficquet, X.; Smith, D.J. [Department of Mechanical Engineering, University of Bristol, Queen' s Building, University Walk, Bristol BS8 1TR (United Kingdom); Truman, C.E. [Department of Mechanical Engineering, University of Bristol, Queen' s Building, University Walk, Bristol BS8 1TR (United Kingdom)], E-mail: c.e.truman@bristol.ac.uk; Kingston, E.J. [Veqter Ltd, University Gate East, Park Row, Bristol BS1 5UB (United Kingdom); Dennis, R.J. [Frazer-Nash Consultancy Limited, 1 Trinity Street, College Green, Bristol BS1 5TE (United Kingdom)
2009-01-15
This paper presents measurements and predictions of the residual stresses generated by laying a single weld bead on a flat, austenitic stainless steel plate. The residual stress field that is created is strongly three-dimensional and is considered representative of that found in a repair weld. Through-thickness measurements are made using the deep hole drilling technique, and near-surface measurements are made using incremental centre hole drilling. Measurements are compared to predictions at the same locations made using finite element analysis incorporating an advanced, non-linear kinematic hardening model. The work was conducted as part of an European round robin exercise, coordinated as part of the NeT network. Overall, there was broad agreement between measurements and predictions, but there were notable differences.
Flagella as a novel alignment medium for the measurement of residual dipolar couplings in proteins.
Singh, Himanshu; Shukla, Manish; Rao, Basuthkar J; Chary, Kandala V R
2013-12-18
The two flexible rod-like flagella (∼500 nm in diameter and 5-15 μm long) of Chlamydomonas reinhardtii, a unicellular green alga, can weakly align molecules in an external magnetic field, thereby enabling the measurement of various residual dipolar couplings in solution NMR spectroscopy.
Sloof, R.; van Praag, M.
2015-01-01
Distorted performance measures in compensation contracts elicit suboptimal behavioral responses that may even prove to be dysfunctional (gaming). This paper applies the empirical test developed by Courty and Marschke (2008) to detect whether the widely used class of Residual Income based performance
Design of Low Phase-Noise Integrated Broadband VCO%集成宽带VCO的低相噪设计
姚立华; 郭文胜
2009-01-01
The design methods and ideas of the low phase-noise integrated broadband VCO was presented by analyzing the concept and principle of VCO phase noise. Theoretical analysis was made and mathematical model was established, and it was realized through simulation and optimization design by related software. The obtained phase-noise index of the entire frequency band of the integrated broadband VCO was given. The series of the low phase-noise integrated VCO is of great benefit to system engineers in circuit design. Currently, the designed low phase-noise VCO is widely used in various electronic systems. It plays a significant role in domestic manufacturing key circuit for electronic systems with high performance.%从VCO的相位噪声概念及原理分析入手,论述了集成宽带压控振荡器低相噪的设计方法和设计思路,进行了理论分析和数学模拟,并通过利用相关软件进行仿真、优化设计.获得了低相噪声的宽带振荡器,并给出了各频段集成宽带VCO最终达到的相位噪声指标.低相噪声集成VCO系列产品的成功研制极大地方便了系统设计师的电路设计,该自主研制的低相噪VCO已广泛应用于多种电子系统中,对系统关键电路的国产化、高性能化有着重要意义.
Brunner, E.; Arnold, M.R.; Kremer, W.; Kalbitzer, H.R. [University of Regensburg, Institute of Biophysics and Physical Biochemistry (Germany)
2001-10-15
High-pressure NMR of proteins in solutions currently gains increasing interest. 3D structure determination of proteins under high pressure is, however, so far impossible due to the lack of NOE information. Residual dipolar couplings induced by the addition of magnetically orienting media are known to be capable of replacing NOE information to a very high extent. In the present contribution we study the pressure-wstability of dimyristoylphosphatidylcholine (DMPC)/ dihexanoylphosphatidylcholine (DHPC) bicelles and demonstrate the feasibility of measuring residual dipolar couplings in proteins under high pressure.
Woo, Wan Chuck; EM, Vyacheslav; Lee, Ho Jin; Kim, Kang Soo; Kang, Mi Hyun; Joo, Jong Dae; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)
2010-10-15
The distribution of residual stresses in dissimilar material joints has been extensively studied because of the wide applications of the dissimilar welds in many inevitable complex design structures. Especially the cracking of dissimilar welding has been a long standing issue of importance in many components of the power generation industries such as nuclear power plant, boiling pressure system, and steam generators. In particular, several failure analysis and direct observations have shown that critical fractures have frequently occurred in one side of the dissimilar welded parts. For example, the heat-affected zone on the ferrite steel side is known to critical in many dissimilar welding pipes when ferrite (low carbon steel) and austenite (stainless) steels are joined. The main cause of the residual stresses can be attributed to the mismatch in the coefficient of thermal expansion between the dissimilar metals (ferrite and austenite). Additional cladding over circumferential welds is known to reinforce the mechanical property due to the beneficial compressive residual stress imposed on the weld and heat-affected zone. However, science-based quantitative measurement of the through thickness residual stress distribution is very limited in literature. The deep penetration capability of neutrons into most metallic materials makes neutron diffraction a powerful tool to investigate and map the residual stresses of materials throughout the thickness and across the weld. Furthermore, the unique volume averaged bulk characteristic of materials and mapping capability in three dimensions are suitable for the engineering purpose. Thus, the neutron-diffraction measurement method has been selected as the most useful method for the study of the residual stresses in various dissimilar metal welded structures. The purpose of this study is to measure the distribution of the residual stresses in a complex dissimilar joining with overlay in the weld pipe. Specifically, we measured
Barile, Claudia; Casavola, Caterina; Pappalettera, Giovanni; Pappalettere, Carmine
2014-01-01
Hole drilling is the most widespread method for measuring residual stress. It is based on the principle that drilling a hole in the material causes a local stress relaxation; the initial residual stress can be calculated by measuring strain in correspondence with each drill depth. Recently optical techniques were introduced to measure strain; in this case, the accuracy of the final results depends, among other factors, on the proper choice of the area of analysis. Deformations are in fact analyzed within an annulus determined by two parameters: the internal and the external radius. In this paper, the influence of the choice of the area of analysis was analysed. A known stress field was introduced on a Ti grade 5 sample and then the stress was measured in correspondence with different values of the internal and the external radius of analysis; results were finally compared with the expected theoretical value.
Phase Noise Analysis of Clock Recovery Based on an Optoelectronic Phase-Locked Loop
Zibar, Darko; Mørk, Jesper; Katsuo Oxenløwe, Leif; Clausen, Anders T.
2007-03-01
A detailed theoretical analysis of a clock-recovery (CR) scheme based on an optoelectronic phase-locked loop is presented. The analysis emphasizes the phase noise performance, taking into account the noise of the input data signal, the local voltage-controlled oscillator (VCO), and the laser employed in the loop. The effects of loop time delay and the laser transfer function are included in the stochastic differential equations describing the system, and a detailed timing jitter analysis of this type of optoelectronic CR for high-speed optical-time-division-multiplexing systems is performed. It is shown that a large loop length results in a higher timing jitter of the recovered clock signal. The impact of the loop length on the clock signal jitter can be reduced by using a low-noise VCO and a low loop filter bandwidth. Using the model, the timing jitter of the recovered optical and electrical clock signal can be evaluated. We numerically investigate the timing jitter requirements for combined electrical/optical local oscillators, in order for the recovered clock signal to have less jitter than that of the input signal. The timing jitter requirements for the free-running laser and the VCO are more relaxed for the extracted optical clock (lasers's output) signal.
Controlled longitudinal emittance blow-up using band-limited phase noise in CERN PSB
Quartullo, D.; Shaposhnikova, E.; Timko, H.
2017-07-01
Controlled longitudinal emittance blow-up (from 1 eVs to 1.4 eVs) for LHC beams in the CERN PS Booster is currently achievied using sinusoidal phase modulation of a dedicated high-harmonic RF system. In 2021, after the LHC injectors upgrade, 3 eVs should be extracted to the PS. Even if the current method may satisfy the new requirements, it relies on low-power level RF improvements. In this paper another method of blow-up was considered, that is the injection of band-limited phase noise in the main RF system (h=1), never tried in PSB but already used in CERN SPS and LHC, under different conditions (longer cycles). This technique, which lowers the peak line density and therefore the impact of intensity effects in the PSB and the PS, can also be complementary to the present method. The longitudinal space charge, dominant in the PSB, causes significant synchrotron frequency shifts with intensity, and its effect should be taken into account. Another complication arises from the interaction of the phase loop with the injected noise, since both act on the RF phase. All these elements were studied in simulations of the PSB cycle with the BLonD code, and the required blow-up was achieved.
BCH Codes for Coherent Star DQAM Systems with Laser Phase Noise
Leong, Miu Yoong; Larsen, Knud J.; Jacobsen, Gunnar; Zibar, Darko; Sergeyev, Sergey; Popov, Sergei
2017-03-01
Coherent optical systems have relatively high laser phase noise, which affects the performance of forward error correction (FEC) codes. In this paper, we propose a method for selecting Bose-Chaudhuri-Hocquenghem (BCH) codes for coherent systems with star-shaped constellations and M-ary differential quadrature amplitude modulation (DQAM). Our method supports constellations of any order M which is a power of 2, and includes differential M-ary phase shift keying as a special case. Our approach is straightforward, requiring only short pre-FEC simulations to parameterize a statistical model, based on which we select codes analytically. It is applicable to pre-FEC bit error rates (BERs) of around 10-3. We evaluate the accuracy of our approach using numerical simulations. For a target post-FEC BER of 10-5, codes selected with our method yield BERs within 2× target. Lastly, we extend our method to systems with interleaving, which enables us to use codes with lower overhead.
Li, Linqian; Feng, Yiqiao; Zhang, Wenbo; Cui, Nan; Xu, Hengying; Tang, Xianfeng; Xi, Lixia; Zhang, Xiaoguang
2017-07-01
A joint carrier recovery scheme for polarization division multiplexing (PDM) coherent optical transmission system is proposed and demonstrated, in which the extended Kalman filter (EKF) is exploited to estimate and equalize the carrier frequency offset (CFO) and carrier phase noise (CPN) simultaneously. The proposed method is implemented and verified in the PDM-QPSK system and the PDM-16QAM system with the comparisons to conventional improved Mth-power (IMP) algorithm for CFO estimation, blind phase search (BPS) algorithm or Viterbi-Viterbi (V-V) algorithm for CPN recovery. It is demonstrated that the proposed scheme shows high CFO estimation accuracy, with absolute mean estimation error below 1.5 MHz. Meanwhile, the proposed method has the CFO tolerance of [±3 GHz] for PDM-QPSK system and [±0.9 GHz] for PDM-16QAM system. Compare with IMP/BPS and IMP/V-V, the proposed scheme can enhance the linewidth symbol duration product from 3 × 10-4 (IMP/BPS) and 2 × 10-4 (IMP/V-V) to 1 × 10-3 for PDM-QPSK, and from 1 × 10-4 (IMP/BPS) to 3 × 10-4 for PDM-16QAM, respectively, at the 1 dB optical signal-to-noise ratio (OSNR) penalty. The proposed Kalman filter also shows a fast convergence with only 100 symbols and much lower computational complexity.
Measurement of Residual Stress Field of Hardfacing Metal with RE Oxide and Its Numerical Simulation
杨庆祥; 姚枚
2003-01-01
The temperature and residual stress fields of a medium-high carbon steel, welded by a cracking resistance electrode with rare earth (RE) oxide, were measured by thermo-vision analyzer and X-ray stress analyzer respectively. Meanwhile, the martensitic transformation temperatures of matrix, hard-face welding (hardfacing) metal welded by conventional hardfacing electrode and that welded by cracking resistance electrode with RE oxide were determined. According to the expe rimental data and the thermo-physical, mechanical parameters of materials, finite element method (FEM) of temperature and stress fields was established. In this FEM, the effect of martensitic transformation on residual stress of hardfacing metal of medium-high carbon steel was taken into account. The results show that, by adding RE oxide in the coat of hardfacing electrode, the martensitic trans formation temperature can be decreased, so that the residual tensile stress on the dangerous position can be decreased. Therefore, the cracking resistance of hardfacing metal can be improved.
Residual Strains in a Nanometer Thick Cr Film Measured on Micromachined Beams
Z.M. Zhou; Yong Zhou; Ying Cao; Haiping Mao
2009-01-01
A Cr film with a 75 nm thickness sputtered on a Si substrate was used to fabricate microbridge and microcan-tilever samples with the MEMS (microelectromechanical system) technique. The profile of the buckled beams was measured by using the interference technique with white light and fitted with a theoretical result. The uniform residual strain in the bridge samples was deduced from the variation of buckling amplitude with the beam length. On the other hand, the gradient residual strain was determined from the deflection profile of the cantilever. The residual uniform and gradient strain in the Cr film are about 4.96×10-3 and 4.2967×10-5, respectively.
Quasi-residual strain and moduli measurements in materials using embedded acoustic waveguides
Harrold, Ronald T.; Sanjana, Zal N.; Raju, Basavaraju B.
1996-11-01
Following the processing and manufacture of resin and composite parts and during their lifetime, the distribution of internal residual strain and any variations in moduli are generally unknown. Real-time information on these parameters would be valuable for improving material performance and reliability. It is believed that measurements related to material residual stresses or strain and moduli can be obtained by measuring the longitudinal wave velocities within acoustic waveguides (AWG) embedded within a material. The concept is that the wave velocities within embedded AWG are related to the material bulk modulus, density and Poisson's Ratio which are all in some degree related to the material state of cure, and finally the internal residual stresses. Based on this concept it is shown that the AWG of different diameters embedded within the same resin part of uniform internal stress distribution, the AWG wave velocities should vary in relation to the square root of the AWG diameter. Experimental results using AWG of 5, 10, 16, 20, 40 and 62 mil diameter Nichrome embedded within Shell 815 clear resin with optically measured uniform strain, demonstrate a direct relationship between AWG velocities and the square root of the AWG diameter. Consequently, it is reasoned that for a part with several embedded AWG, each of the same diameter, then differences in the AWG velocities would yield information on differences in the residual strain and moduli within the part.
Kim, Kang Soo; Lee, Ho Jin; Woo, Wan Chuck; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo; Jung, In Chul [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)
2010-10-15
Much research has been done to estimate the residual stress on a dissimilar metal weld. There are many methods to estimate the weld residual stress and FEM (Finite Element Method) is generally used due to the advantage of the parametric study. And the X-ray method and a Hole Drilling technique for an experimental method are also usually used. The aim of this paper is to develop the appropriate FEM model to estimate the residual stresses of the dissimilar overlay weld pipe. For this, firstly, the specimen of the dissimilar overlay weld pipe was manufactured. The SA 508 Gr3 nozzle, the SA 182 safe end and SA376 pipe were welded by the Alloy 182. And the overlay weld by the Alloy 52M was performed. The residual stress of this specimen was measured by using the Neutron Diffraction device in the HANARO (High-flux Advanced Neutron Application ReactOr) research reactor, KAERI (Korea Atomic Energy Research Institute). Secondly, FEM Model on the dissimilar overlay weld pipe was made and analyzed by the ABAQUS Code (ABAQUS, 2004). Thermal analysis and stress analysis were performed, and the residual stress was calculated. Thirdly, the results of the FEM analysis were compared with those of the experimental methods
A new nondestructive instrument for bulk residual stress measurement using tungsten kα1 X-ray
Ma, Ce; Dou, Zuo-yong; Chen, Li; Li, Yun; Tan, Xiao; Dong, Ping; Zhang, Jin; Zheng, Lin; Zhang, Peng-cheng
2016-11-01
We describe an experimental instrument used for measuring nondestructively the residual stress using short wavelength X-ray, tungsten kα1. By introducing a photon energy screening technology, the monochromatic X-ray diffraction of tungsten kα1 was realized using a CdTe detector. A high precision Huber goniometer is utilized in order to reduce the error in residual stress measurement. This paper summarizes the main performance of this instrument, measurement depth, stress error, as opposed to the neutron diffraction measurements of residual stress. Here, we demonstrate an application on the determination of residual stress in an aluminum alloy welded by the friction stir welding.
Shizuma, K.; Endo, S. [Faculty of Engineering, Hiroshima Univ., Higashi-Hiroshima (Japan); Hoshi, M. [Research Institute for Radiation Biology and Medicine, Hiroshima Univ., Kasumi, Hiroshima (JP)] [and others
2000-05-01
Residual {sup 152}Eu activity produced by neutrons from the Nagasaki atomic bomb has been measured in seven mineral samples located up to 1142 m from the epicenter. Europium was chemically separated from the sample and gamma-ray measurement was carried out with a well-type Ge detector. Deduced specific activities were compared with previous measurements and with activation calculation based on the DS86 neutron fluence. Present results are slightly higher than the calculation at far distances. However, systematic discrepancy as has been observed in Hiroshima is not clear. Further measurements for samples beyond 1000 m from the hypocenter are necessary to ensure the discrepancy problem. (author)
Acoustic Measurements of Residual Stresses and Grain Sizes in Aluminum Alloys
Fisher, Martin John
The theory of acoustoelasticity relates the velocity of an acoustic wave in a solid to the elastic stress state in that solid. This thesis presents new theories, measurement techniques, and methodologies related to the use of longitudinal wave acoustoelasticity in aluminum alloys. A one-dimensional model has been developed to provide a simple understanding of the acoustoelastic effect. A new acoustic device for accurately measuring relative thickness variations has been designed and built. This device is used--in conjunction with a pulse-echo phase measurement device and a computer controlled scanning system--to measure acoustic velocity variations in plastically deformed and non-flat-and-parallel samples. Acoustic velocity variations from point to point in an unstressed sample can sometimes be on the same order as velocity changes due to applied or residual stresses, and this can make stress measurements difficult. A statistical theory has been developed to relate these unstressed velocity variations to the average grain size in the sample and to the active area of the acoustic transducer used. Large transducers and small grain sizes will minimize these variations. This relationship has been verified by tests on a number of aluminum alloys and a new method for non-destructive grain size determination has been suggested. A systematic methodology has been developed and tested for studying the influence of uniaxial plastic deformation on the acoustoelastic response. Samples have been plastically deformed in four-point bending to produce elastic-plastic and residual stress states. Acoustic measurements of these stresses have then been compared directly to theoretical predictions based on the materials' stress-strain curves and simple beam theory. In the aluminum alloys tested (2024-T351 and 7075-T651), the acoustoelastic constants are shown to be virtually unchanged by uniaxial plastic strains of less than 2.5%. Thus, the acoustoelastic technique can be reliably
Residual stress measurement by successive extension of a slot: A literature review
Prime, M.B.
1997-05-01
This report reviews the technical literature on techniques that employ successive extension of a slot and the resulting deformations to measure residual stress. Such techniques are known variously in the literature as the compliance or crack compliance method, the successive cracking method, the slotting method, and a fracture mechanics based approach. The report introduces the field and describes the basic aspects of these methods. The report then reviews all literature on the theoretical developments of the method. The theory portion first considers forward method solutions including fracture mechanics, finite element, analytical, and body force methods. Then it examines inverse solutions, including incremental inverses and series expansions. Next, the report reviews all experimental applications of slotting methods. Aspects reviewed include the specimen geometry and material, the details of making the slot, the method used to measure deformation, and the theoretical solutions used to solve for stress. Finally, the report makes a brief qualitative comparison between slotting methods and other residual stress measurement methods.
Campos, Wagner R.C.; Rabello, Emerson G.; Mansur, Tanius R.; Scaldaferri, Denis H.B.; Paula, Raphael G., E-mail: wrcc@cdtn.br, E-mail: egr@cdtn.br, E-mail: tanius@cdtn.br, E-mail: dhbs@cdtn.br, E-mail: tanius@cdtn.br, E-mail: raphaelmecanica@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Souto, Joao P.R.S.; Carvalho Junior, Ideir T., E-mail: joprocha@yahoo.com.br, E-mail: ideir_engenharia@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Metalurgica
2013-07-01
Weld residual stresses have a large influence on the behavior of cracking that could possibly occur under normal operation of components. In case of an unfavorable environment, both stainless steel and nickel-based weld materials can be susceptible to stress-corrosion cracking (SCC). Stress corrosion cracks were found in dissimilar metal welds of some pressurized water reactor (PWR) nuclear plants. In the nuclear reactor primary circuit the presence of tensile residual stress and corrosive environment leads to so-called Primary Water Stress Corrosion Cracking (PWSCC). The PWSCC is a major safety concern in the nuclear power industry worldwide. PWSCC usually occurs on the inner surface of weld regions which come into contact with pressurized high temperature water coolant. However, it is very difficult to measure the residual stress on the inner surfaces of pipes or nozzles because of inaccessibility. A mock-up of weld parts of a pressurizer safety nozzle was fabricated. The mock-up was composed of three parts: an ASTM A508 C13 nozzle, an ASTM A276 F316L stainless steel safe-end, an AISI 316L stainless steel pipe and different filler metals of nickel alloy 82/182 and AISI 316L. This work presents the results of measurements of residual strain from the outer surface of the mock-up welded in base metals and filler metals by hole-drilling strain-gage method of stress relaxation. (author)
Liangbao Liu; Jianfei Sun; Wuyi Chen; Pengfei Sun
2015-01-01
Residual stress is one of the factors affecting the machining deformation of monolithic structure parts in the aviation industry. Thus, the studies on machining deformation rules induced by residual stresses largely depend on correctly and efficiently measuring the residual stresses of workpieces. A modified layer⁃removal method is proposed to measure residual stress by analysing the characteristics of a traditional layer⁃removal method. The coefficients of strain release are then deduced according to the simulation results using the finite element method ( FEM) . Moreover, the residual stress in a 7075T651 aluminium alloy plate is measured using the proposed method, and the results are then analyzed and compared with the data obtained by the traditional methods. The analysis indicates that the modified layer⁃removal method is effective and practical for measuring the residual stress distribution in pre⁃stretched aluminium alloy plates.
Hartnett, John G; Lu, Chuan
2012-01-01
Two nominally identical ultra-stable cryogenic microwave oscillators are compared. Each incorporates a dielectric-sapphire resonator cooled to near 6 K in an ultra-low vibration cryostat using a low-vibration pulse-tube cryocooler. The phase noise for a single oscillator is measured at -105 dBc/Hz at 1 Hz offset on the 11.2 GHz carrier. The oscillator fractional frequency stability is characterized in terms of Allan deviation by 5.3 x 10^-16 tau^-1/2 + 9 x 10^-17 for integration times 0.1 s < tau < 100 s and is limited by a flicker frequency noise floor below 1 x 10^-16.
Measurements of thermal residual stresses in SiC/Ti-15-3 composites
Bobet, J.-L.; Masuda, C. [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)
1997-06-01
Residual stresses present in an as received and thermally cycled SCS-6/Ti-15-3 metal matrix composite (MMC) have been approached via X-ray diffraction (sin{sup 2}{psi}) experiments. Determination of stress profiles have been achieved by successive removal of the matrix from the composite surface by electropolishing. Axial and hoop stresses in the matrix were tensile (higher on the surface) and those measured in the fiber were compressive (about -500 to -600 MPa). A stress gradient normal to the surface of the composite was found. Measurement of residual stress levels in the composite subjected to thermal cycling from 400degC to 800degC in an inert atmosphere or in vacuum revealed a huge stress relaxation after only 200 cycles. (author)
Jie Cheng; Si-Young Kwak; Ho-Young Hwang
2010-01-01
In this study,residual stresses in heat treated specimen were measured by using ESPI(Electronic Speckle-Pattern Interferometry)combined with the hole-drilling method.The specimen,made of SUS 304austenitic stainless steel,was quenched and water cooled to room temperature.Numerical simulation using a hybrid FDM/FEM package was also carried out to simulate the heat treatment process.As a result,the thermal stress fields were obtained from both the experiment and the numerical simulation.By comparision of stress fields,results from the experimental method and numerical simulation well agreed to each other,therefore,it is proved that the presented experimental method is applicable and reliable for heat treatment induced residual stress measurement.
Nahmani, Samuel; Bock, Olivier
2013-04-01
Six permanent GPS stations have been deployed in West Africa within the framework of the African Monsoon Multidisciplinary Analysis (AMMA) project in order to monitor precipitable water vapor (PWV) estimates. This quantity turns out to be relevant for computing water budgets to study atmospheric processes associated with the monsoon precipitations. 90% of annual rainfalls in Sahel are produced by Mesoscale Convective Systems (MCSs). During these extreme meteorological conditions, the residuals of GPS phase measurements show strong variations that are spatially and temporally correlated with the passages of the MCSs. Using in-situ observations of pressure, temperature and humidity, brightness temperatures from Meteosat and measurements of reflectivity from MIT C-band Doppler radar, we analysed the cases of MCS over Niamey (Niger) during the whole rainy season of 2006. We found some signals in GPS phase residuals in connection with the structure of MCS. These signals could be used to better understand and classify these extreme meteorological events.
Measurement and tailoring of residual stress in expanded austenite on austenitic stainless steel
Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Winther, Grethe
2017-01-01
Expanded austenite on stainless steel with a high interstitial nitrogen content is characterized by elasto-plastic accommodation of the large composition-induced lattice expansion leading to huge compressive residual stress. The elasto-plastic accommodation as well as the (steep) concentration...... profile has implications for the measurement strategy to determine lattice strains and associated residual stresses with X-ray diffraction. Lattice strain measurements were performed on nitrided as well as subsequently de-nitrided expanded austenite on AISI 316L stainless steel, for various grazing...... stresses in expanded austenite can be tailored by de-nitriding after nitriding, such that a condition of virtually zero stress at the surface is obtained....
Development of procedures for the measurement of residual stress by neutron diffraction
Webster, G A
2002-01-01
Neutron diffraction is a non-destructive method for determining residual stresses in crystalline materials. It is a relatively new technique and no standard is currently available for making these measurements. This paper gives the background to research that has been carried out to develop a standard. It outlines the main findings and indicates the precautions that are required to achieve accurate positioning and alignment of specimens (and components) in a neutron beam and the analysis required to obtain reliable results. It also shows that special attention is needed in dealing with near-surface measurements because of surface aberration. It is demonstrated that, provided the recommended procedures are followed, a positional tolerance of +-0.1 mm can be achieved with an accuracy in strain of propor to 10 sup - sup 4 , to give a resolution in residual stress of propor to 7 to 20 MPa in most materials of practical interest. (orig.)
Li, H.; Liu, Y. H.
2008-11-01
The hole-drilling strain gage method is an effective semi-destructive technique for determining residual stresses in the component. As a mechanical technique, a work-hardening layer will be formed on the surface of the hole after drilling, and affect the strain relaxation. By increasing Young's modulus of the material near the hole, the work-hardening layer is simplified as a heterogeneous annulus. As an example, two finite rectangular plates submitted to different initial stresses are treated, and the relieved strains are measured by finite element simulation. The accuracy of the measurement is estimated by comparing the simulated residual stresses with the given initial ones. The results are shown for various hardness of work-hardening layer. The influence of the relative position of the gages compared with the thickness of the work-hardening layer, and the effect of the ratio of hole diameter to work-hardening layer thickness are analyzed as well.
Jacobsen, Gunnar; Xu, Tianhua; Popov, Sergei; Friberg, Ari T; Zhang, Yimo
2016-01-01
In this paper we present a comparative study in order to specify the influence of equalization enhanced phase noise (EEPN) for pre- and post-compensation of chromatic dispersion in high capacity and high constellation systems. This is - to our knowledge - the first detailed study in this area for pre-compensation systems. Our main results show that the local oscillator phase noise determines the EEPN influence in post-compensation implementations whereas the transmitter laser determines the EEPN in pre-compensation implementations. As a result of significance for the implementation of practical longer-range systems it is to be emphasized that the use of chromatic dispersion equalization in the optical domain - e.g. by the use of dispersion compensation fibers - eliminates the EEPN entirely. Thus, this seems a good option for such systems operating at high constellations in the future.
Xu, Tianhua; Popov, Sergei; Li, Jie; Sergeyev, Sergey; Friberg, Ari T; Liu, Tiegen; Zhang, Yimo
2016-01-01
The performance of long-haul coherent optical fiber transmission system is significantly affected by the equalization enhanced phase noise (EEPN), due to the interaction between the electronic dispersion compensation (EDC) and the laser phase noise. In this paper, we present a comprehensive study on different chromatic dispersion (CD) compensation and carrier phase recovery (CPR) approaches, in the n-level phase shift keying (n-PSK) and the n-level quadrature amplitude modulation (n-QAM) coherent optical transmission systems, considering the impacts of EEPN. Four CD compensation methods are considered: the time-domain equalization (TDE), the frequency-domain equalization (FDE), the least mean square (LMS) adaptive equalization are applied for EDC, and the dispersion compensating fiber (DCF) is employed for optical dispersion compensation (ODC). Meanwhile, three carrier phase recovery methods are also involved: a one-tap normalized least mean square (NLMS) algorithm, a block-wise average (BWA) algorithm, and a...
Mohajerin-Ariaei, Amirhossein; Ziyadi, Morteza; Almaiman, Ahmed; Cao, Yinwen; Alishahi, Fatemeh; Chitgarha, Mohammad Reza; Fallahpour, Ahmad; Yang, Jeng-Yuan; Bao, Changjing; Liao, Peicheng; Shamee, Bishara; Akasaka, Youichi; Sekiya, Motoyoshi; Touch, Joseph D; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Willner, Alan E
2016-10-15
Simultaneous phase noise mitigation and automatic phase/frequency-locked homodyne reception is demonstrated for a 20-32 Gbaud QPSK signal. A phase quantization function is realized to squeeze the phase noise of the signal by optical wave mixing of the signal, its third-order harmonic, and their corresponding delayed variant conjugates, converting the noisy input into a noise-mitigated signal. In a simultaneous nonlinear process, the noise-mitigated signal is automatically phase- and frequency-locked with a "local" pump laser, avoiding the need for feedback or phase/frequency tracking for homodyne detection. Open eye-diagrams are obtained for in-phase and quadrature-phase components of the signal and ∼2 dB OSNR gain is achieved at BER 10-3.
Okido, Shinobu; Hayashi, Makoto [Hitachi Ltd., Tokyo (Japan); Morii, Yukio; Minakawa, Nobuaki; Tsuchiya, Yoshinori
1997-06-01
In a residual stress measurement by x-ray diffraction method and a neutron diffraction method, strictly speaking, the strain measurement of various diffracted surface was conducted and it is necessary to use its elastic modulus to convert from the strain to the stress. Then, in order to establish the residual stress measuring technique using neutron diffraction, it is an aim at first to make clear a diffraction surface dependency of elastic modulus for the stress conversion in various alloys. As a result of investigations the diffraction surface dependency of elastic module on SUS304 and STS410 steels by using RESA (Neutron diffractometer for residual stress analysis) installed at JRR-3M in Tokai Establishment of JAERI, following results are obtained. The elastic modulus of each diffraction surface considering till plastic region could be confirmed to be in a region of {+-}20% of that calculated by Kroner`s model and to be useful for that used on conversion to the stress. And, error of this elastic modulus was thought to cause the transition and defect formed at inner portion of the materials due to a plastic deformation. (G.K.)
Measurement and modeling of residual stress in a welded Haynes[reg] 25 cylinder
Larsson, C. [Div. of Eng. Mat., Department of Mech. Eng., Linkoeping University, 58183 Linkoeping (Sweden)]. E-mail: clarsson@cfl.rr.com; Holden, T.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Stout, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Teague, J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lindgren, L.-E. [Div. Comp. Aided Design, Lulea University of Technology and Dalarna University, 97187 Lulea (Sweden)
2005-06-15
An experimental and simulation study of residual stresses was made in the vicinity of a gas tungsten arc weld, used to join a hemispherical end cap to a cylinder. The capped cylinder is used in a satellite application and was fabricated from a Co-based Haynes[reg] 25 alloy. The cylinder was 34.7 mm in outer diameter and 3.3 mm in thickness. The experimental measurements were made by neutron diffraction and the simulation used the implicit Marc finite element code. The experimental resolution was limited to approximately 3 mm parallel to the axis of the cylinder (the weld was 6 mm in the same direction) and comparison over the same volume of the finite element prediction showed general agreement. Subject to the limited spatial resolution, the largest experimentally measured tensile residual stress was 180 MPa, located at the middle of the weld. However, the predictions suggest that there are regions in the weld where average tensile residual stresses as much as 400 MPa exist. One qualitative disparity between the model and the experiments was that the measurement included a larger degree of asymmetry on either side of the weld than predicted by the model.
2014-06-08
Based Parametric Bifurcation Tracking of Mip -Coated Microbeam MEMS Sensor for TNT Explosive Gas Sensing See Attached The views, opinions and/or...2050 1 ABSTRACT Phase Noise-Squeezing-Based Parametric Bifurcation Tracking of Mip -Coated Microbeam MEMS Sensor for TNT Explosive Gas Sensing...SQUEEZING BASED PARAMETRIC BIFURCATION TRACKING OF MIP -COATED MICROBEAM MEMS SENSOR FOR TNT EXPLOSIVE GAS SENSING L. L. Li1*, E. L. Holthoff2, L. A
WANGShu-hong; ZUODun-wen; WANGMin; WANGZong-rong
2004-01-01
The integrated structure parts are widely used in aircraft. The distortion caused by residual stresses in thick pre-stretched aluminum plates during machining integrated parts is a common and serious problem. To predict and control the machining distortion, the residual stress distribution in the thick plate must be measured firstly. The modified removal method for measuring residual stress in thick pre-stretched aluminum plates is proposed and the stress-strain relation matrix is deduced by elasticity theory. The residual stress distribution in specimen of 7050T7451 plate is measured by using the method, and measurement results are analyzed and compared with data obtained by other methods. The method is effective to measure the residual stress.
A 2.4 GHz high-linearity low-phase-noise CMOS LC-VCO based on capacitance compensation
Li Zhenrong; Zhuang Yiqi; Li Bing; Jin Gang; Jin Zhao, E-mail: allen_lzr@126.co [Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China)
2010-07-15
A 2.4 GHz high-linearity low-phase-noise cross-coupled CMOS LC voltage-controlled oscillator (VCO) is implemented in standard 0.18-{mu}m CMOS technology. An equalization structure for tuning sensitivity base on the three-stage distributed biased switched-varactor bank and the differential switched-capacitor bank is adopted to reduce the variations of the VCO gain, achieve high linearity, and optimize the phase-noise performance. Compared to the conventional VCO, the proposed VCO has more constant gain over the entire tuning range. The tuning range is about 18.7% from 2.23 to 2.69 GHz, and the phase noise is -95 dBc/Hz at 100-kHz offset and -117 dBc/Hz at 1-MHz offset from the carrier frequency of 2.42 GHz. The power dissipation is 2.1 mW from a 1.8 V power supply. The active area of this VCO is 500 x 810 {mu}m{sup 2}.
Liu, Yue; Yang, Chuanchuan; Yang, Feng; Li, Hongbin
2014-03-24
Digital coherent passive optical network (PON), especially the coherent orthogonal frequency division multiplexing PON (OFDM-PON), is a strong candidate for the 2nd-stage-next-generation PON (NG-PON2). As is known, OFDM is very sensitive to the laser phase noise which severely limits the application of the cost-effective distributed feedback (DFB) lasers and more energy-efficient vertical cavity surface emitting lasers (VCSEL) in the coherent OFDM-PON. The current long-reach coherent OFDM-PON experiments always choose the expensive external cavity laser (ECL) as the optical source for its narrow linewidth (usuallyOFDM-PON and study the possibility of the application of the DFB lasers and VCSEL in coherent OFDM-PON. A typical long-reach coherent ultra dense wavelength division multiplexing (UDWDM) OFDM-PON has been set up. The numerical results prove that the OBE method can stand severe phase noise of the lasers in this architecture and the DFB lasers as well as VCSEL can be used in coherent OFDM-PON. In this paper, we have also analyzed the performance of the RF-pilot-aided (RFP) phase noise suppression method in coherent OFDM-PON.
Robert, Clélia; Conan, Jean-Marc; Wolf, Peter
2016-06-01
Bidirectional ground-satellite laser links suffer from turbulence-induced scintillation and phase distortion. We study how turbulence impacts on coherent detection capacity and on the associated phase noise that restricts clock transfer precision. We evaluate the capacity to obtain a two-way cancellation of atmospheric effects despite the asymmetry between up and down link that limits the link reciprocity. For ground-satellite links, the asymmetry is induced by point-ahead angle and possibly the use, for the ground terminal, of different transceiver diameters, in reception and emission. The quantitative analysis is obtained thanks to refined end- to-end simulations under realistic turbulence and wind conditions as well as satellite cinematic. These temporally resolved simulations allow characterizing the coherent detection in terms of time series of heterodyne efficiency for different system parameters. We show that Tip/Tilt correction on ground is mandatory at reception for the down link and as a pre-compensation of the up link. Good correlation between up and down phase noise is obtained even with asymmetric apertures of the ground transceiver and in spite of pointing ahead angle. The reduction to less than 1 rad2 of the two-way differential phase noise is very promising for clock comparisons.
The Characteristic of Residual Charge for Water-tree Degraded XLPE and the Measurement Method
Ebinuma, Yasumitsu; Masui, Noriaki
Recently the measurement of residual charge has been studying as insulation deterioration diagnosis of XLPE insulated cables. Authors have studied the measurement process and the charge characteristic. The specimens are XLPE sheets of 1mm which are degraded with water-trees. There are four processes of charge removal, charge injection, ground and charge release in the measurement. The process of charge removal was introduced to measure a little charge successfully. In the process of charge injection, it was confirmed that the relation between the applied dc voltage and the charge was examined, and the higher dc voltage was, more the charge was. In addition, it has been showed that the applied process of the dc voltage greatly influences the measured charge. In the process of ground, the grounding period is changed and the charge is measured. It has been showed that the grounding period doesn't influence the measured charge greatly. In the process of charge release, the frequency and the period of applied ac voltage were changed and the charge was measured. It has been showed that neither the frequency nor the period of ac voltage greatly influence the charge measured. In addition, the dc voltage was superimposed to ac voltage, and the charge was measured. It has been showed that the charge measured changes greatly even if the dc voltage is low. The method of the insulation deterioration measurement of cable was examined from these results, and the measurement conditions and a newer method were suggested.
Vaidya, R.U.; Rangaswamy, P.; Bourke, M.A.M.; Butt, D.P. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.
1998-03-23
Neutron diffraction was used to measure the bulk residual strains in molybdenum disilicide (MoSi{sub 2})-316L stainless steel joints. The joints were produced by brazing disks of MoSi{sub 2} and 316L stainless steel along with an interlayer, using Cusil{trademark} as the braze. This study explored the physical parameters of the interlayer on the average phase strains in the MoSi{sub 2} and 316L stainless steel. The effect of the coefficient of thermal expansion was explored by using three different interlayer materials: niobium, nickel, and nickel-iron. The residual strains in MoSi{sub 2} decreased significantly in both radial and axial directions with increasing niobium interlayer thickness. Residual strains were relatively insensitive to changes in 500 {micro}m thick interlayer material. Finite element modeling results were corroborated by the neutron measurements on the joints allowing inferences to be drawn concerning the preference of the interlayer material. The results illustrate the importance of the ductile interlayer in the successful fabrication of MoSi{sub 2}-316L stainless steel joints.
B Shabankhani
2006-01-01
Full Text Available Introduction: Considering the importance and usefulness of fruits in people’s daily diet as they play an important role in determining public health and also considering the significance of pesticide residues in foods and fruits , measurement of which has been repeatedly reiterated by WHO and FAO, this research was done. Irregular use of pesticides by farmers knowingly or unknowingly without observing its caress period has led to the contact of these pesticides with humans through foods and fruits and in the long run, they will surely cause chronic complications . Methods: In this study, after collecting cucumbers form 76 sample regions, we rinsed them carefully, sliced them thinly and mashed them up. Then, we extracted them three times with n butyl acetate. Later, we evaporated the solvent. At the end, we measured the residue by chromatographic gas (GC and detector (ECD. Results and Conclusion: The results obtained were analyzed with the help of two-way ANOVA. It indicated that there is a correlation between the investigated regions and the residual amount (P>0.05. Calculation of the mean ratings showed that the levels of these two pesticides are higher than the acceptable level in most of the regions. (0.01
Fiori, F.; Girardin, E.; Giuliani, A.;
2000-01-01
, residual stresses are present in both the matrix and the particles microstructure, prior to any macroscopic loading. They vary with the temperature and with the type and level of loading imposed to the material, having a strong influence on the mechanical behaviour of MMCs. Neutron diffraction measurements...... have been performed at RISO (Roskilde, DK) and HMI-BENSC (Berlin, D), for the determination of residual stress in AA2124 + 17% SiCp and AA359 + 20% SiCp specimens, submitted to tensile and fatigue tests. For each of the investigated samples, the macrostress has been separated from the elastic...... and thermal mismatch microstresses. The results show that, in general, the main contribution to the stress state of both matrix and reinforcement is given by the thermal microstresses, already existing due to heat treatment prior to mechanical tests. (C) 2000 Elsevier Science B.V. All rights reserved....
Neutron diffraction measurements and modeling of residual strains in metal matrix composites
Saigal, A.; Leisk, G. G.; Hubbard, C. R.; Misture, S. T.; Wang, X. L.
1996-01-01
Neutron diffraction measurements at room temperature are used to characterize the residual strains in tungsten fiber-reinforced copper matrix, tungsten fiber-reinforced Kanthal matrix, and diamond particulate-reinforced copper matrix composites. Results of finite element modeling are compared with the neutron diffraction data. In tungsten/Kanthal composites, the fibers are in compression, the matrix is in tension, and the thermal residual strains are a strong function of the volume fraction of fibers. In copper matrix composites, the matrix is in tension and the stresses are independent of the volume fraction of tungsten fibers or diamond particles and the assumed stress free temperature because of the low yield strength of the matrix phase.
Phase noise analysis of a 0.18um CMOS fractional-N PLL for 802.11 a/b/g/n applications
Hiebert, Mark Allen
2006-01-01
In integrated CMOS 802.11 a/b/g/n direct conversion transceivers a key performance characteristic is the RMS value of RF clock phase noise at offsets between 1kHz and 20MHz. Phase noise analysis concepts related to fractional-N PLLs are presented and an optimization exercise determining PLL characteristics for a O.18pm CMOS fractional-N PLL in an 802.11 a/b/g/n RF frequency generation application is described. For fractional-N PLLs, modelling fractional-N phase noise effects and optimizing PL...
Ilias Chlis
2014-01-01
Full Text Available This paper reports comparative analyses of phase noise in Hartley, Colpitts, and common-source cross-coupled differential pair LC oscillator topologies in 28 nm CMOS technology. The impulse sensitivity function is used to carry out both qualitative and quantitative analyses of the phase noise exhibited by each circuit component in each circuit topology with oscillation frequency ranging from 1 to 100 GHz. The comparative analyses show the existence of four distinct frequency regions in which the three oscillator topologies rank unevenly in terms of best phase noise performance, due to the combined effects of device noise and circuit node sensitivity.
Chlis, Ilias; Pepe, Domenico; Zito, Domenico
2014-01-01
This paper reports comparative analyses of phase noise in Hartley, Colpitts, and common-source cross-coupled differential pair LC oscillator topologies in 28 nm CMOS technology. The impulse sensitivity function is used to carry out both qualitative and quantitative analyses of the phase noise exhibited by each circuit component in each circuit topology with oscillation frequency ranging from 1 to 100 GHz. The comparative analyses show the existence of four distinct frequency regions in which the three oscillator topologies rank unevenly in terms of best phase noise performance, due to the combined effects of device noise and circuit node sensitivity.
Deng, Lei; Pang, Xiaodan; Tafur Monroy, Idelfonso
2014-01-01
We propose a nonlinearity and phase noise tolerant orthogonal frequency division multiplexing (OFDM) W-band signal over fiber system based on phase modulation and photonic heterodyne up-conversion techniques. By heterodyne mixing the phase-modulated optical OFDM signal with a free-running laser...... in the photodiode, the constant envelope OFDM W-band wireless signal is obtained to suppress the nonlinear impairments. Moreover, the phase noises of the beating lasers appear as additive terms to the desired signal, and could be easily filtered out without complex phase noise estimation and compensation algorithms...
Measuring multiple residual-stress components using the contour method and multiple cuts
Prime, Michael B [Los Alamos National Laboratory; Swenson, Hunter [Los Alamos National Laboratory; Pagliaro, Pierluigi [U. PALERMO; Zuccarello, Bernardo [U. PALERMO
2009-01-01
The conventional contour method determines one component of stress over the cross section of a part. The part is cut into two, the contour of the exposed surface is measured, and Bueckner's superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The stress results are validated against independent measurements using neutron diffraction. The theory has implications beyond just multiple cuts. The contour method measurements and calculations for the first cut reveal how the residual stresses have changed throughout the part. Subsequent measurements of partially relaxed stresses by other techniques, such as laboratory x-rays, hole drilling, or neutron or synchrotron diffraction, can be superimposed back to the original state of the body.
李旺; 唐俊
2012-01-01
分析了频率源中各个模块的噪声传递函数,确定影响近端噪声的模块分别是鉴频鉴相器_电荷泵(PFD_CP)、分频器；在默认分频器相位噪声为-158 dBc/Hz,通过matlab建模推断,需要PFD-CP模块在10 kHz频偏处的输入噪声达到-143 dBc/Hz,才能实现频率源输出信号在10 kHz频偏处相位噪声-107 dBc/Hz.采用0.18μmSiGe BiCMOS工艺,设计了整块芯片,着重优化了PFD-CP模块的输入噪声,经过spectre仿真,PFD_CP模块的输入噪声为-146 dBc/Hz,经过实测,输出信号在10 kHz频偏处相位噪声为-108 dBc/Hz,达到设计预期.%Based on analysis of the phase noise model of the frequency synthesizer, it is known that the PFD-CP (phase frequency detector and charge pump) noise and the divider noise are the main contributer of the phase noise. By using matlab model if the divider phase noise of - 158 dBc/Hz, is default value PFD_CP must attain -143 dBc/Hz at 10 kHz offset in order to realize the designed synthesizer phase noise of -107 dBc/Hz. The frequency synthesizer chip has been designed in 0. 18μm SiGe BiCMOS technology, simulated results by spectre show that charge pump noise is -146 dBc/Hz at 10 kHz. Measured phase noise of the frequency synthesizer is -108 dBc/Hz@10 kHz at 3 GHz.
Residual Resistivity Ratio (RRR) Measurements of LHC Superconducting NbTi Cable Strands
Charifoulline, Z
2006-01-01
The Rutherford-type superconducting NbTi cables of the LHC accelerator are currently manufactured by six industrial companies. As a part of the acceptance tests, the Residual Resistivity Ratio (RRR) of superconducting strands is systematically measured on virgin strands to qualify the strands before cabling and on extracted strands to qualify the cables and to check the final heat treatment (controlled oxidation to control interstrand resistance). More than 12000 samples of virgin and extracted strands have been measured during last five years. Results show good correlation with the measurements done by the companies and reflect well the technological process of cable production (strand annealing, cabling, cable heat treatment). This paper presents a description of the RRR-test station and the measurement procedure, the summary of the results over all suppliers and finally the correlation between RRR-values of the cables and the magnets.
Montalto, L; Paone, N; Scalise, L; Rinaldi, D
2015-06-01
The assessment of the stress state of scintillating crystals is an important issue for producers as well as users of such materials, because residual stress may arise during growth process. In this paper, a measurement system, based on the use of a photoelastic, conoscopic optical setup, is proposed for the assessment of stress state in scintillating crystals. Local stress values can be measured on the crystal in order to observe their spatial distribution. With the proposed system, it is possible to vary the dimensions of the inspected measurement volume. It has been validated with reference to a known stress state induced in a birefringent crystal sample and it has been tested for the case of loaded and unloaded samples, showing sub-millimetric spatial resolution and stress uncertainty ≤0.25 MPa. The proposed measurement system is a valid method for the inspection of scintillating crystals required by producers and users of such materials.
Aristides T Hatjimihail
Full Text Available BACKGROUND: An open problem in clinical chemistry is the estimation of the optimal sampling time intervals for the application of statistical quality control (QC procedures that are based on the measurement of control materials. This is a probabilistic risk assessment problem that requires reliability analysis of the analytical system, and the estimation of the risk caused by the measurement error. METHODOLOGY/PRINCIPAL FINDINGS: Assuming that the states of the analytical system are the reliability state, the maintenance state, the critical-failure modes and their combinations, we can define risk functions based on the mean time of the states, their measurement error and the medically acceptable measurement error. Consequently, a residual risk measure rr can be defined for each sampling time interval. The rr depends on the state probability vectors of the analytical system, the state transition probability matrices before and after each application of the QC procedure and the state mean time matrices. As optimal sampling time intervals can be defined those minimizing a QC related cost measure while the rr is acceptable. I developed an algorithm that estimates the rr for any QC sampling time interval of a QC procedure applied to analytical systems with an arbitrary number of critical-failure modes, assuming any failure time and measurement error probability density function for each mode. Furthermore, given the acceptable rr, it can estimate the optimal QC sampling time intervals. CONCLUSIONS/SIGNIFICANCE: It is possible to rationally estimate the optimal QC sampling time intervals of an analytical system to sustain an acceptable residual risk with the minimum QC related cost. For the optimization the reliability analysis of the analytical system and the risk analysis of the measurement error are needed.
Campos, Wagner R.C.; Rabello, Emerson G.; Silva, Luiz L.; Mansur, Tanius R., E-mail: wrcc@cdtn.br, E-mail: egr@cdtn.br, E-mail: silvall@cdtn.br, E-mail: tanius@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte (Brazil). Servico de Integridade Estrutural; Martins, Ketsia S., E-mail: ketshinoda@hotmail.com [Universidade Federal de Minas Gerais (UFMG), Nelo Horizonte (Brazil). Departamento de Engenharia Metalurgica
2015-07-01
Residual stresses are present in materials or structural component in the absence of external loads or changes in temperatures. The most common causes of residual stresses being present are the manufacturing or assembling processes. All manufacturing processes, such as casting, welding, machining, molding, heat treatment, among others, introduces residual stresses into the manufactured object. The residual stresses effects could be beneficial or detrimental, depending on its distribution related to the component or structure, its load service and if it is compressive or tensile. In this work, the residual strains and stresses inside a mock-up that simulates the safety and relief nozzle of Angra 1 Nuclear Power Plant pressurizer were studied. The current paper presents a blind hole-drilling method residual stress measurements both at the inner surface of dissimilar metal welds of dissimilar metal weld nozzle mock-up. (author)
Chen, Hsi-Chao; Huang, Kuo-Ting; Lo, Yen-Ming
2012-04-01
This study constructed a measurement system that can quickly and accurately analyze the residual stress of flexible electronics. A double beam shadow moiré interferometer was set up to measure and evaluate the residual stress of tin-doped indium oxide films on a polyethylene terephthalate substrate. However, this system required only two symmetrical fringes to evaluate the residual stress of transparent conductive oxide films on flexible substrate. Applying the grating translation techniques to the double beam shadow moiré interferometer greatly improved the measurement resolution and accuracy, and the relative error was reduced to 1.2%.
Shiue, Sham-Tsong; Lin, Hung-Chien; Shen, Ting-Ying; Ouyang, Hao
2005-06-01
The residual stress measurement in carbon coatings of optical fibers is theoretically and experimentally investigated. A simple formula used to measure the residual stresses in the thin film deposited on a cylindrical substrate with the bending curvature is proposed. During a temperature drop, the carbon-coated optical fiber is bent due to the nonuniform deposition of coating materials. The axial residual stresses in carbon coatings of optical fibers can be measured from the fiber bending curvature and coating thickness difference. Furthermore, if Young's modulus of carbon coatings is known, the thermal expansion coefficient of carbon coatings can be determined.
Jiang, Y; Poggiolini, P; Forghieri, F
2014-01-01
We accurately characterize nonlinear phase noise in uncompensated coherent optical systems. We find that, though present, its impact on system performance is typically negligible in a wide range of practical system scenarios.
A new dynamical diffraction-based technique of residual stress measurements in thin films
Agamalian, M; Kaiser, H; Rehm, C; Werner, S A
2002-01-01
The recently discovered dynamical diffraction effect 'neutron camel' was used for residual stress measurements in a thick Si (111) crystal coated with a 2000 A-thick Ni film. The observed asymmetry of the back-face rocking curve corresponds to the bending radius of propor to 19 km and the tension force applied to the Ni film is propor to 90 N/m. Relative deformation of the Si crystallographic cells in the vicinity of diffractive surfaces is vertical stroke partial deriv u sub z /partial deriv z vertical stroke approx 1.6 x 10 sup - sup 6. (orig.)
Rand, Kasper D; Zehl, Martin; Jensen, Ole Nørregaard
2009-01-01
Because of unparalleled sensitivity and tolerance to protein size, mass spectrometry (MS) has become a popular method for measuring the solution hydrogen (1H/2H) exchange (HX) of biologically relevant protein states. While incorporated deuterium can be localized to different regions by pepsin...... the HX of individual amide linkages in the amyloidogenic protein beta2-microglobulin. A comparison of the deuterium levels of 60 individual backbone amides of beta2-microglobulin measured by HX-ETD-MS analysis to the corresponding values measured by NMR spectroscopy shows an excellent correlation......-phase hydrogen (1H/2H) migration (i.e., hydrogen scrambling). This article demonstrates that ETD can be implemented in a mass spectrometric method to monitor the conformational dynamics of proteins in solution at single-residue resolution....
Heterogeneous Integration for Reduced Phase Noise and Improved Reliability of Semiconductor Lasers
Srinivasan, Sudharsanan
Significant savings in cost, power and space are possible in existing optical data transmission networks, sensors and metrology equipment through photonic integration. Photonic integration can be broadly classified into two categories, hybrid and monolithic integration. The former involves assembling multiple single functionality optical devices together into a single package including any optical coupling and/or electronic connections. On the other hand monolithic integration assembles many devices or optical functionalities on a single chip so that all the optical connections are on chip and require no external alignment. This provides a substantial improvement in reliability and simplifies testing. Monolithic integration has been demonstrated on both indium phosphide (InP) and silicon (Si) substrates. Integration on larger 300mm Si substrates can further bring down the cost and has been a major area of research in recent years. Furthermore, with increasing interest from industry, the hybrid silicon platform is emerging as a new technology for integrating various active and passive optical elements on a single chip. This is both in the interest of bringing down manufacturing cost through scaling along with continued improvement in performance and to produce multi-functional photonic integrated circuits (PIC). The goal of this work is twofold. First, we show four laser demonstrations that use the hybrid silicon platform to lower phase noise due to spontaneous emission, based on the following two techniques, viz. confinement factor reduction and negative optical feedback. The first two demonstrations are of mode-locked lasers and the next two are of tunable lasers. Some of the key results include; (a) 14dB white frequency noise reduction of a 20GHz radio-frequency (RF) signal from a harmonically mode-locked long cavity laser with greater than 55dB supermode noise suppression, (b) 8dB white frequency noise reduction from a colliding pulse mode-locked laser by
Jacobsen, Gunnar; Xu, Tianhua; Popov, Sergei; Li, Jie; Friberg, Ari T; Zhang, Yimo
2012-04-09
A radio frequency (RF) carrier can be used to mitigate the phase noise impact in n-level PSK and QAM systems. The systems performance is influenced by the use of an RF pilot carrier to accomplish phase noise compensation through complex multiplication in combination with discrete filters to compensate for the chromatic dispersion (CD). We perform a detailed study comparing two filters for the CD compensation namely the fixed frequency domain equalizer (FDE) filter and the adaptive least-mean-square (LMS) filter. The study provides important novel physical insight into the equalization enhanced phase noise (EEPN) influence on the system bit-error-rate (BER) versus optical signal-to-noise-ratio (OSNR) performance. Important results of the analysis are that the FDE filter position relative to the RF carrier phase noise compensation module provides a possibility for choosing whether the EEPN from the Tx or the LO laser influences the system quality. The LMS filter works very inefficiently when placed prior to the RF phase noise compensation stage of the Rx whereas it works much more efficiently and gives almost the same performance as the FDE filter when placed after the RF phase noise compensation stage.
Wang, Danshi; Zhang, Min; Cai, Zhongle; Cui, Yue; Li, Ze; Han, Huanhuan; Fu, Meixia; Luo, Bin
2016-06-01
An effective machine learning algorithm, the support vector machine (SVM), is presented in the context of a coherent optical transmission system. As a classifier, the SVM can create nonlinear decision boundaries to mitigate the distortions caused by nonlinear phase noise (NLPN). Without any prior information or heuristic assumptions, the SVM can learn and capture the link properties from only a few training data. Compared with the maximum likelihood estimation (MLE) algorithm, a lower bit-error rate (BER) is achieved by the SVM for a given launch power; moreover, the launch power dynamic range (LPDR) is increased by 3.3 dBm for 8 phase-shift keying (8 PSK), 1.2 dBm for QPSK, and 0.3 dBm for BPSK. The maximum transmission distance corresponding to a BER of 1 ×10-3 is increased by 480 km for the case of 8 PSK. The larger launch power range and longer transmission distance improve the tolerance to amplitude and phase noise, which demonstrates the feasibility of the SVM in digital signal processing for M-PSK formats. Meanwhile, in order to apply the SVM method to 16 quadratic amplitude modulation (16 QAM) detection, we propose a parameter optimization scheme. By utilizing a cross-validation and grid-search techniques, the optimal parameters of SVM can be selected, thus leading to the LPDR improvement by 2.8 dBm. Additionally, we demonstrate that the SVM is also effective in combating the laser phase noise combined with the inphase and quadrature (I/Q) modulator imperfections, but the improvement is insignificant for the linear noise and separate I/Q imbalance. The computational complexity of SVM is also discussed. The relatively low complexity makes it possible for SVM to implement the real-time processing.
一种改进的相位噪声抑制方法%An improved phase noise suppression method
王赓浡; 战勇杰; 陈昕; 陈茹梅
2015-01-01
随着卫星数传容量急剧增加，高阶调制解调方式在实际中被广泛采用，卫星通信系统的性能有了更高的要求。针对这一现状，给出一种基于最小均方根的相位噪声抑制算法，能够通过对相位噪声的抑制来有效地提高高阶调制解调系统误码性能。 MATLAB仿真证明，改进的噪声抑制算法相比之前的基本噪声补偿算法对高阶调制解调系统的相位噪声有更好的抑制能力，能够进一步提高系统信噪比，降低系统误码率。%With the increasing capacity of remote sensing satellite data transmission, when high order modulation and demodulation is widely used, the request of the system performance is much higher. According this situation, this paper proposes an improved method to reduce phase noise. This paper improved the performance of system with reducing the affect of phase noise. Through the MATLAB simulation, the method have a better performance of reducing the phase noise and the system has better performance and lower BER.
Residual stresses in a quenched superalloy turbine disc: Measurements and modeling
Rist, M. A.; James, J. A.; Tin, S.; Roder, B. A.; Daymond, M. R.
2006-02-01
A series of neutron diffraction measurements have been carried out to determine the elastic residual strains deep within a large, 40-cm-diameter, forged and water-quenched IN718 aeroengine compressor disc. Neutron path lengths of up to 6 cm were necessary to probe the thickest parts of the forging, and three-dimensional strain and stress components have been derived for the first time in such a large superalloy specimen. Measurements have been compared with the results from a coupled thermal-mechanical finite-element model of the quenching process, based upon appropriate temperature-dependent material properties, with some success. The general residual stress state in the disc is one of near-surface compression, balanced by tension within the disc interior. The steepest stress and strain gradients occur in the transition region from compression to tension, about 1 cm below the surface all around the disc. The largest stress component is in the disc tangential direction and reaches a magnitude of 400 to 500 MPa near the disc surface and at its core. This exceeds the effective yield stress because of the presence of significant hydrostatic stress.
Fogarassy, Paul; Cofino, Bruno; Millet, Pierre; Lodini, Alain
2005-07-01
The thermal deposition of hydroxyapatite (HA) on titanium alloy substrate (Ti-6A1-4V) leads to a structure that has very good osseointegration properties. However, clinical failures have been occasionally reported at the interface between substrate and coating. Lifetime is the main parameter in such prostheses; therefore, in order to improve their quality, it is necessary to evaluate the level of stresses near the interface. The high-energy synchrotron radiation combines the advantages of a bulk analysis and reduced volume of the gauge. The objective of our study was to calculate the residual stress using a nonlinear finite-element model and to measure residual stress level near the interface, in the hydroxyapatite coating and in titanium alloy substrate with a nondestructive and high-resolution experiment. The high-energy synchrotron radiation of the BM16 beam-line at ESRF (Grenoble-France) was used with a resolution of down to 10 micrometers. The experimental measurements validate the results found by means of nonlinear finite-element analysis of the plasma spraying induced stress.
The Optimum Design Methodology of Low-Phase-Noise LC-VCO Using Multiple-Divide Technique
Hara, Shoichi; Murakami, Rui; Okada, Kenichi; Matsuzawa, Akira
The multiple-divide technique, using the multi-ratio frequency divider, has a possibility to improve FoM of VCO. This paper proposes a design optimization of LC-VCO using the multiple-divide technique. In the simulated results using 90-nm CMOS model parameters, the optimum frequency range, achieving better than -187.0dBc/Hz of FoM, can be extended from 6.5-12.5GHz to 1.5-12.5GHz. The proposed multiple-divide technique can provide a lower phase-noise, lower power consumption, smaller layout area of LC-VCO.
Tsvelykh, I. S.; B. A. Kotserzhynskyi
2016-01-01
This work demonstrates push-push VCOs in K-band (with second harmonic output at 24 GHz) and in Ka-band (with third harmonic output at 36 GHz), and PLL synthesizers on their basis. Oscillators are stabilized by a rectangular resonant metallic cavity. Output signal power within the frequency tuning range changes in the limits of -11,5 -7,6 dBm and -11,8 -10,9 dBm for 24 GHz and 36 GHz oscillators respectively. Single sideband (SSB) phase noise spectral densities of -91 dBc/Hz for 24 GHz oscilla...
Measurement of residual stresses in the dissimilar metal weld joint of a safe-end nozzle mock-up
Ogawa, Kazuo (Japan Nuclear Energy Safety Organisation, Tokyo (Japan)); Kingston, E.; Chidwick, L. (VEQTER Ltd., Bristol (United Kingdom)); Smith, D. (Univ. of Bristol (United Kingdom))
2009-07-01
Knowledge of the origin, magnitude and distribution of residual stresses generated during the manufacture of nuclear power plants is of vital importance to their structural integrity assessment. The overall aim of this work was to measure welding residual stresses in components prone to primary water stress corrosion cracking in nuclear reactor pressure vessels. This paper describes the on-site application of the Deep-Hole Drilling (DHD) technique to measure the through-thickness residual stress distributions through a safe-end nozzle component containing a dissimilar metal weld joint at different stages of manufacture
Measurement of residual CO2 saturation at a geological storage site using hydraulic tests
Rötting, T. S.; Martinez-Landa, L.; Carrera, J.; Russian, A.; Dentz, M.; Cubillo, B.
2012-12-01
Estimating long term capillary trapping of CO2 in aquifers remains a key challenge for CO2 storage. Zhang et al. (2011) proposed a combination of thermal, tracer, and hydraulic experiments to estimate the amount of CO2 trapped in the formation after a CO2 push and pull test. Of these three types of experiments, hydraulic tests are the simplest to perform and possibly the most informative. However, their potential has not yet been fully exploited. Here, a methodology is presented to interpret these tests and analyze which parameters can be estimated. Numerical and analytical solutions are used to simulate a continuous injection in a porous medium where residual CO2 has caused a reduction in hydraulic conductivity and an increase in storativity over a finite thickness (a few meters) skin around the injection well. The model results are interpreted using conventional pressure build-up and diagnostic plots (a plot of the drawdown s and the logarithmic derivative d s / d ln t of the drawdown as a function of time). The methodology is applied using the hydraulic parameters estimated for the Hontomin site (Northern Spain) where a Technology Demonstration Plant (TDP) for geological CO2 storage is planned to be set up. The reduction of hydraulic conductivity causes an increase in observed drawdowns, the increased storativity in the CO2 zone causes a delay in the drawdown curve with respect to the reference curve measured before CO2 injection. The duration (characteristic time) of these effects can be used to estimate the radius of the CO2 zone. The effects of reduced permeability and increased storativity are well separated from wellbore storage and natural formation responses, even if the CO2-brine interface is inclined (i.e. the CO2 forms a cone around the well). We find that both skin hydraulic conductivity and storativity (and thus residual CO2 saturation) can be obtained from the water injection test provided that water flow rate is carefully controlled and head build
Oceanic residual depth measurements, the plate cooling model, and global dynamic topography
Hoggard, Mark J.; Winterbourne, Jeff; Czarnota, Karol; White, Nicky
2017-03-01
Convective circulation of the mantle causes deflections of the Earth's surface that vary as a function of space and time. Accurate measurements of this dynamic topography are complicated by the need to isolate and remove other sources of elevation, arising from flexure and lithospheric isostasy. The complex architecture of continental lithosphere means that measurement of present-day dynamic topography is more straightforward in the oceanic realm. Here we present an updated methodology for calculating oceanic residual bathymetry, which is a proxy for dynamic topography. Corrections are applied that account for the effects of sedimentary loading and compaction, for anomalous crustal thickness variations, for subsidence of oceanic lithosphere as a function of age and for non-hydrostatic geoid height variations. Errors are formally propagated to estimate measurement uncertainties. We apply this methodology to a global database of 1936 seismic surveys located on oceanic crust and generate 2297 spot measurements of residual topography, including 1161 with crustal corrections. The resultant anomalies have amplitudes of ±1 km and wavelengths of ˜1000 km. Spectral analysis of our database using cross-validation demonstrates that spherical harmonics up to and including degree 30 (i.e., wavelengths down to 1300 km) are required to accurately represent these observations. Truncation of the expansion at a lower maximum degree erroneously increases the amplitude of inferred long-wavelength dynamic topography. There is a strong correlation between our observations and free-air gravity anomalies, magmatism, ridge seismicity, vertical motions of adjacent rifted margins, and global tomographic models. We infer that shorter wavelength components of the observed pattern of dynamic topography may be attributable to the presence of thermal anomalies within the shallow asthenospheric mantle.
Lee, Kyoung Soo; Kim, W.; Lee, Jeong Geun; Park, Chi Yong; Yang, Jun Seok; Kim, Tae Ryong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Park, Jai Hak [Chungbuk University, Cheongju (Korea, Republic of)
2009-11-15
Finite element (FE) analysis and experiment for weld residual stress (WRS) in the pressurizer safety nozzle mockup is described in various processes and results. Foremost of which is the dissimilar simulation metal welding (DMW) between carbon steel and austenitic stainless steel. Thermal and structural analyses were compared with actual residual stress, and actual measurements of. Magnitude and distribution of WRS in the nozzle mockup were assessed. Two measurement methods were used: hole-drilling method (HDM) with strain gauge for residual stress on the surface of the mockup, and block removal and splitting layer (BRSL) method for through-thickness. FE analysis and measurement data showed good agreement. In conclusion, the characteristics of weld residual stress of DMW could be well understood and the simplified FE analysis was verified as acceptable for estimating WRS
Davenport, Andrew
2016-05-01
Residual renal function is associated with improved survival and quality of life for dialysis patients. Whereas residual renal function is monitored in peritoneal dialysis patients, many hemodialysis centers simply concentrate on achieving dialyzer urea clearance targets. Accurately quantifying residual renal function from urine collections is arduous. Thus, there is a clinical need to develop alternative methods of assessing residual renal function based on serum testing, especially for patients receiving less than thrice weekly dialysis.
Enzymatic activity measured by microcalorimetry in soil amended with organic residues
Karina Cenciani
2011-08-01
Full Text Available Enzymatic activity is an important property for soil quality evaluation. Two sequences of experiments were carried out in order to evaluate the enzymatic activity in a soil (Rhodic Eutrudox amended with cattle manure, earthworm casts, or sewage sludges from the municipalities of Barueri and Franca. The activity of commercial enzymes was measured by microcalorimetry in the same soil samples after sterilization. In the first experiment, the enzyme activities of cellulase, protease, and urease were determined in the soil samples during a three month period. In the second sequence of experiments, the thermal effect of the commercial enzymes cellulase, protease, and urease on sterilized soil samples under the same tretaments was monitored for a period of 46 days. The experimental design was randomized and arranged as factorial scheme in five treatments x seven samplings with five replications. The treatment effects were statistically evaluated by one-way analysis of variance. Tukey´s test was used to compare means at p < 0.05. The presence of different sources of organic residues increased the enzymatic activity in the sampling period. Cattle manure induced the highest enzymatic activity, followed by municipal sewage sludge, whereas earthworm casts induced the lowest activity, but differed from control treatment. The thermal effect on the enzyme activity of commercial cellulase, protease, and urease showed a variety of time peaks. These values probably oscillated due to soil physical-chemical factors affecting the enzyme activity on the residues.
Masoud Amirpour
2015-12-01
Full Text Available Introducing the novel technique for enhancing oil recovery from available petroleum reservoirs is one of the important issues in future energy demands. Among of all operative factors, wettability may be the foremost parameter affecting residual oil saturation in all stage of oil recovery. Although wettability alteration is one of the methods which enhance oil recovery from the petroleum reservoir. Recently, the studies which focused on this subject were more than the past and many contributions have been made on this area. The main objective of the current study is experimentally investigation of the two nonionic surfactants effects on altering wettability of reservoir rocks. Purpose of this work is to change the wettability to preferentially the water-wet condition. Also reducing the residual oil saturation (Sor is the other purpose of this work. The wettability alteration of reservoir rock is measured by two main quantitative methods namely contact angle and the USBM methods. Results of this study showed that surfactant flooding is more effective in oil-wet rocks to change their wettability and consequently reducing Sor to a low value. Cedar (Zizyphus Spina Christi is low priced, absolutely natural, and abundantly accessible in the Middle East and Central Asia. Based on the results, this material can be used as a chemical surfactant in field for enhancing oil recovery.
Non-stationary model residuals: information, disinformation and measures of information
Beven, K.
2012-12-01
We expect error in applying hydrological models. They are approximate representations of hydrological processes, driven by approximate estimates of boundary fluxes and compared against uncertain observations of discharge (and perhaps other observables). We should expect, from the nonlinear dynamics of hydrological responses and the epistemic nature of many of the sources of uncertainty, that the residuals should be non-stationary in character. This suggests that it might be difficult to find a simple representation of the error characteristics that could be used, for example, to define a likelihood function for parameter estimation. This is often ignored: the likelihood functions used in hydrology have generally been simple, aleatory and stationary (albeit that this is not a conceptual limitation - as one referee put it, in principle an error model can be infinitely complex!). However, the epistemic nature of the uncertainty does raise the issue of how far nonstationary model residuals might be informative about change in the system and how far they reflect epistemic disinformation in inferring the true nature of the system. Some periods of potential calibration data are clearly disinformative in inference (even if informative about observational techniques), but other unusual events might be particularly revealing about the process responses. Is it therefore possible to define measures of information that can reflect some of these difficulties prior to running a model, or must we resort to data assimilation conditional on a model in detecting nonstationarity?
Measuring residual feed intake in dairy heifers fed an alfalfa (Medicago sativa) cube diet.
Waghorn, G C; Macdonald, K A; Williams, Y; Davis, S R; Spelman, R J
2012-03-01
Selection for divergence between individuals for efficiency of feed utilization (residual feed intake, RFI) has widespread application in the beef industry and is usually undertaken when animals are fed diets based on silages with grain. The objective of this research was to develop a feeding system (using Gallagher, Hamilton, New Zealand, electronics) to measure RFI for growth in Holstein-Friesian heifers (aged 5-9 mo), and identify divergent individuals to be tested for RFI during lactation. A dry forage diet (alfalfa cubes) was fed because intakes could be measured accurately, and the New Zealand dairy industry (4.4 million milking cows in lactation) relies heavily on forage feeding. The evaluation was undertaken over 3 yr with 1,052 animals fed in a facility for 7 wk, and weighed 3 times weekly. The mean age at the start of measurements was 215 d, body weight (BW) 189 kg, and mean daily dry matter intakes averaged 6.7 kg. Body weight gain (all animals) averaged 0.88 kg/d. The RFI was determined as the residuals from the regression of mean intake on mean BW(0.75) and daily BW gain of individuals. Actual and fitted intakes were strongly related (R(2) = 0.82). In terms of gross efficiency (feed intake/BW gain), RFI+year explained 43% of the variation, BW gain+year explained 66%, and RFI+BW gain+year explained 79% of the variation (all Pdry matter/d. The most and least efficient animals will be tested for RFI during lactation and genetic markers will be identified for the trait.
Xu, Tianhua; Liga, Gabriele; Lavery, Domaniç; Thomsen, Benn C.; Savory, Seb J.; Killey, Robert I.; Bayvel, Polina
2015-09-01
Superchannel transmission spaced at the symbol rate, known as Nyquist spacing, has been demonstrated for effectively maximizing the optical communication channel capacity and spectral efficiency. However, the achievable capacity and reach of transmission systems using advanced modulation formats are affected by fibre nonlinearities and equalization enhanced phase noise (EEPN). Fibre nonlinearities can be effectively compensated using digital back-propagation (DBP). However EEPN which arises from the interaction between laser phase noise and dispersion cannot be efficiently mitigated, and can significantly degrade the performance of transmission systems. Here we report the first investigation of the origin and the impact of EEPN in Nyquist-spaced superchannel system, employing electronic dispersion compensation (EDC) and multi-channel DBP (MC-DBP). Analysis was carried out in a Nyquist-spaced 9-channel 32-Gbaud DP-64QAM transmission system. Results confirm that EEPN significantly degrades the performance of all sub-channels of the superchannel system and that the distortions are more severe for the outer sub-channels, both using EDC and MC-DBP. It is also found that the origin of EEPN depends on the relative position between the carrier phase recovery module and the EDC (or MC-DBP) module. Considering EEPN, diverse coding techniques and modulation formats have to be applied for optimizing different sub-channels in superchannel systems.
Xu, Tianhua; Liga, Gabriele; Lavery, Domaniç; Thomsen, Benn C; Savory, Seb J; Killey, Robert I; Bayvel, Polina
2015-09-14
Superchannel transmission spaced at the symbol rate, known as Nyquist spacing, has been demonstrated for effectively maximizing the optical communication channel capacity and spectral efficiency. However, the achievable capacity and reach of transmission systems using advanced modulation formats are affected by fibre nonlinearities and equalization enhanced phase noise (EEPN). Fibre nonlinearities can be effectively compensated using digital back-propagation (DBP). However EEPN which arises from the interaction between laser phase noise and dispersion cannot be efficiently mitigated, and can significantly degrade the performance of transmission systems. Here we report the first investigation of the origin and the impact of EEPN in Nyquist-spaced superchannel system, employing electronic dispersion compensation (EDC) and multi-channel DBP (MC-DBP). Analysis was carried out in a Nyquist-spaced 9-channel 32-Gbaud DP-64QAM transmission system. Results confirm that EEPN significantly degrades the performance of all sub-channels of the superchannel system and that the distortions are more severe for the outer sub-channels, both using EDC and MC-DBP. It is also found that the origin of EEPN depends on the relative position between the carrier phase recovery module and the EDC (or MC-DBP) module. Considering EEPN, diverse coding techniques and modulation formats have to be applied for optimizing different sub-channels in superchannel systems.
Neutron scattering instruments for residual stress/strain measurements at KUR
Ono, Masayoshi [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.
1997-06-01
A Kyoto University Reactor project research finished on March, 1997 is a first trial in Japan. In this research, some residual stress measurement in accompany with thermal and processing deformation history of various superconductive composite wires and so on were conducted to obtain a lot of research results. At TOF system, simultaneous measurement of the direction dependent collective texture using a multi point detector was useful, and at PSD system the strain measurement in a region under 10{sup -4} became possible to conduct. In addition, it is intending now to establish high performance instruments such as a two-stage type disc chopper at the TOF system and a high resolution vent type Si monocrystal monochromator at the PSD system. In particular, it is expected a the TOF system that a direction dependent collective texture and a stress distribution state in various kinds of functional materials can be measured simultaneously and without destruction. The mechanical property research of the metallic materials using low speed neutron scattering method is now a big interest in and out of Japan. This research contains a lot of contents coinciding to the industrial fields in an application research field of nuclear basic research and is expected in future to powerfully promote international cooperative research and to deeply recognize its usefulness and importance. (G.K.)
Modified Shear Box Test Apparatus for Measuring Shear Strength of Unsaturated Residual Soil
Bujang B.K. Huat
2005-01-01
Full Text Available Residual soils occur in most countries of the world but the greater areas and depths are normally found in tropical humid areas. Most of these soils exhibit high suctions for most of the year. The shear strength parameters, c’ and Î¦’, of soil can be obtained using conventional shear strength tests. However the conventional shear strength test equipments would not be able to measure Î¦b value (change of shear strength to change in suction without certain modification to them. This study describes the modifications that have been made to a standard shear box test apparatus to enable it to test soil samples in unsaturated conditions. The modifications include fabrication of an air pressure chamber, modifications of the shear box assembly inside the air pressure chamber, modification to the normal loading system, as well as additions of data acquisition devices to enhance the performance and simplify the usage of the modified shear box test apparatus.
Masoomi, Mohammad; Shamsaei, Nima; Winholtz, Robert A; Milner, Justin L; Gnäupel-Herold, Thomas; Elwany, Alaa; Mahmoudi, Mohamad; Thompson, Scott M
2017-08-01
Neutron diffraction was employed to measure internal residual stresses at various locations along stainless steel (SS) 17-4 PH specimens additively manufactured via laser-powder bed fusion (L-PBF). Of these specimens, two were rods (diameter=8 mm, length=80 mm) built vertically upward and one a parallelepiped (8×80×9 mm(3)) built with its longest edge parallel to ground. One rod and the parallelepiped were left in their as-built condition, while the other rod was heat treated. Data presented provide insight into the microstructural characteristics of typical L-PBF SS 17-4 PH specimens and their dependence on build orientation and post-processing procedures such as heat treatment. Data have been deposited in the Data in Brief Dataverse repository (doi:10.7910/DVN/T41S3V).
Mohammad Masoomi
2017-08-01
Full Text Available Neutron diffraction was employed to measure internal residual stresses at various locations along stainless steel (SS 17-4 PH specimens additively manufactured via laser-powder bed fusion (L-PBF. Of these specimens, two were rods (diameter=8 mm, length=80 mm built vertically upward and one a parallelepiped (8×80×9 mm3 built with its longest edge parallel to ground. One rod and the parallelepiped were left in their as-built condition, while the other rod was heat treated. Data presented provide insight into the microstructural characteristics of typical L-PBF SS 17-4 PH specimens and their dependence on build orientation and post-processing procedures such as heat treatment. Data have been deposited in the Data in Brief Dataverse repository (doi:10.7910/DVN/T41S3V.
Martinov Milan
2006-01-01
Full Text Available Use of crop residues as fuel has a long tradition in rural areas of Serbia. Numerous biomass-fueled facilities were built during the 80s. Among those were small facilities for household heating, with thermal power from 5 to 50 kW, medium-size facilities for farm and greenhouses, with thermal power 50 to 1000 kW, and large facilities for processing of agricultural products, with thermal powers higher than 1000 kW. The results showed that the level of biomass combustion facilities is in general very low. This is especially the case for heating facilities used for house-hold heating. The measures for improvement were proposed. .
Fusion and quasifission studies in reactions forming Rn via evaporation residue measurements
Shamlath, A.; Prasad, E.; Madhavan, N.; Laveen, P. V.; Gehlot, J.; Nasirov, A. K.; Giardina, G.; Mandaglio, G.; Nath, S.; Banerjee, Tathagata; Vinodkumar, A. M.; Shareef, M.; Jhingan, A.; Varughese, T.; Kumar, Dvgrks; Devi, P. Sandya; Khushboo, Jisha, P.; Kumar, Neeraj; Hosamani, M. M.; Kailas, S.
2017-03-01
Background: Formation of the compound nucleus (CN) is highly suppressed by quasifission in heavy-ion collisions involving massive nuclei. Though considerable progress has been made in the understanding of fusion-fission and quasifission, the exact dependence of fusion probability on various entrance channel variables is not completely clear, which is very important for the synthesis of new heavy and superheavy elements. Purpose: To study the interplay between fusion and quasifission in reactions forming CN in the boundary region where the fusion probability starts to deviate from unity. Methods: Fusion evaporation residue cross sections were measured for the Si,3028+180Hf reactions using the Hybrid Recoil Mass Analyser at IUAC, New Delhi. Experimental data were compared with data from other reactions forming the same CN or isotopes of the CN. Theoretical calculations were performed using the dinuclear system and statistical models. Results: Reduced evaporation residue cross sections were observed for the reactions studied compared with the asymmetric reaction forming the same CN, indicating fusion suppression in more symmetric systems. The observations are consistent with fission fragment measurements performed in the same or similar systems. Larger ER cross sections are observed with increase in mass in the isotopic chain of the CN. Conclusions: Fusion probability varies significantly with the entrance channels in reactions forming the same CN. While complete fusion occurs for the 16O+194Pt reaction, the fusion probability drops to approximately 60 -70 % for the 30Si+180Hf and less than 20 % for the 50Ti+160Gd reactions, respectively, forming the same CN at similar excitation energies.
24 GHz Low Phase Noise MMIC Voltage Controlled Oscillator%24 GHz低相位噪声单片集成VCO
谭超
2013-01-01
The 24 GHz MMIC voltage controlled oscillator (VCO)based on the GaAs heterojunction bipolar transistor (GaAs HBT) technology was introduced.The MMIC VCO integrated 1/2 harmonic output and divided-by-8 high speed prescaler for the 1/2 and 1/16 harmonic output frequency.The design of the VCO used push-push structure,the 24 GHz VCO have lower phase noise compared to the traditional design which used the low frequency VCO chips and frequency multiplier cascade technology.The measured results show that the phase noise is-92 dBc/Hz@100 kHz.The VCO can provide frequency from 23 GHz to 25.5 GHz with the tuning voltage from 0 V to 13 V.Output power is 9 dBm with 5 V DC supply.The VCO's phase noise performance is excellent over different temperature,shock and other conditions due to the VCO's monolithic push-push structure.The 1/2 harmonic and divided-by-8 high speed prescaler for a 1/16 harmonic output frequency also provide excellent performance.%介绍了一款基于砷化镓异质结双极晶体管(GaAs HBT)工艺的24 GHz单片压控振荡器(VCO),VCO芯片上同时集成了1/2次谐波输出及八分频器电路,可提供1/2和1/16次谐波输出.由于振荡器采用了推-推压控振荡器(push-push VCO)结构,相比传统的通过低频VCO芯片和倍频器级联技术实现的24 GHz VCO具有更低的相位噪声,测试结果表明芯片在不同温度、振动以及其他条件下表现出良好的相位噪声,在0～13V的电调电压条件下输出频率为23～25.5 GHz,输出功率在5 V直流工作电压条件下为9 dBm,相位噪声低至-92 dBc/Hz@100 kHz.同时1/2次谐波输出及八分频器电路提供的1/16次谐波输出性能良好.
Ko, Dae Hoon; Ko, Dae Cheol; Kim, Byung Min [Pusan National University, Busan (Korea, Republic of); Lim, Hak Jin; Lee, Jung Min [Poongsan Co., Gyungju (Korea, Republic of)
2013-07-15
The purpose of this study is to predict the residual stress resulting from the cryogenic heat treatment (CHT) which affects the mechanical properties and microstructure for Al6061 alloy. The CHT is very effective method to reduce the residual stress by quenching media such as liquid nitrogen, boiling water and steam. In this study, experimental T6 and CHT are carried out to measure the temperature of Al parts and to determine the convective heat transfer coefficient. This coefficient is used to predict the residual stress during FE-simulation. In order to consider the relaxation of residual stress during artificial ageing, the Zener-Wert-Avrami function with elasto-plastic nonlinear analysis is used in this study. The predicted residual stress is compared with the measured one by X-ray diffraction (XRD) and is found to be in good agreement with results of the FE-simulation. Further, after T6 and CHT, the electrical conductivity and hardness of the Al6061 alloy are measured to estimate the mechanical properties and its microstructure such as precipitates is observed by Transmission electron microscopy (TEM). Also, the creation of precipitates during T6 and CHT are verified by XRD with component analysis. It is found that CHT affects the residual stress, mechanical properties, and precipitation of the Al 6061 alloy.
Aníbal Veras Siqueira Filho
2013-04-01
Full Text Available Residual stresses in a welded joint of ASTM A131 grade AH32 steel was measured either by the X-ray diffraction or by displacements of referenced points measured on a coordinate measuring machine before and after heat treatment. For all tests, the welding was performed with Shielded Metal Arc Welding, vertical-up position, by a certified welder. After welding, some specimens were subjected to marking, made through small holes evenly spaced and mapped on a coordinate measuring machine. After labeling, the samples were subjected to heat treatment at temperatures nearby recrystallization. After heat treatment, the samples were subjected to new measurements by coordinate measuring machine to evaluate the displacements of the points produced by the recrystallization. In parallel, residual stress measurements were made by XRD for validation of this new methodology. The results obtained either by X-ray or by coordinate measuring machine showed a good correlation between the two measurement methodologies employed.
刘爱芳; 来弛攀; 仇光锋
2012-01-01
在相位噪声理论模型的基础上,推导出反映相位噪声导致的相参积累损失因子和信噪比.结合单/双基地合成孔径雷达(SAR)的信号收发关系,给出了单/双基地条件下回波相位噪声的关系式,并以典型机载SAR参数进行相噪对聚焦性能的仿真分析.结果表明,相位噪声对双基地SAR的影响明显大于单基地.该分析方法也可应用于其他类型相参雷达的积累性能分析.%Based on the analysis of phase noise model,the expression of integration loss factor (ILF) which is denote to evaluate the effect of phase noise on coherent integration and signal noise ratio (SNR) are given.Using the character of phase noise,the phase noise model of the monostatic and bistatic radar are analyzed and discussed.The simulation experiments of typical airborne synthetic aperture radar (SAR) system have been carried out and the results verify that phase noise has more remarkable effect for bistatic SAR.The approach can be applied to performance analysis of other kind of coherent radar.
Wu, Kan; Li, Xiaohui; Wang, Yonggang; Wang, Qi Jie; Shum, Perry Ping; Chen, Jianping
2015-01-12
We investigate the timing phase noise of fiber lasers mode locked by graphene oxide (GO) and carbon nanotubes (CNTs), respectively, integrated in a linear cavity fiber laser in the reflecting operation. Due to the shorter decay time of the GO and CNTs, weaker slow saturable absorber effects are expected and mode-locked lasers based on these two saturable absorbers exhibit low excess timing phase noise coupled from the laser intensity noise. Compared with a reference laser mode locked by semiconductor saturable absorber mirror (SESAM), GO based laser obtains a timing phase noise reduction of 7 dB at 1 kHz and a timing jitter reduction of 45% experimentally whereas CNTs based laser obtains a timing phase noise reduction of 3 dB and a timing jitter reduction of 29%. This finding suggests that saturable absorbers with short decay time have the potential for achieving mode locking operation with low timing phase noise, which is important for applications including frequency metrology, high-precision optical sampling, clock distribution and optical sensing.
Ishizawa, Atsushi; Nishikawa, Tadashi; Mizutori, Akira; Takara, Hidehiko; Takada, Atsushi; Sogawa, Tetsuomi; Koga, Masafumi
2013-12-02
We investigated phase-noise characteristics of both a phase/intensity-modulated laser with 25-GHz mode spacing and a mode-locked fiber laser with carrier-envelope-offset (CEO) locking. As the separation from the frequency of the continuous wave (CW) laser diode (LD) for a seed light source increases, the integrated phase noise of each comb mode of both the phase/intensity-modulated laser and supercontinuum light originating from it increases with the same slope as a function of mode number. The dependence of the integrated phase noise on mode number with the phase/intensity-modulated laser is much larger than with the mode-locked fiber laser of the CEO locking. However, the phase noise of the phase/intensity-modulated laser is extremely lower than that of the mode-locked fiber laser with CEO locking in the frequency region around the CW LD. The phase noise of the phase/intensity-modulated laser with 25-GHz mode spacing and that of the mode-locked fiber laser with the CEO locking could be estimated and were found to be almost the same at the wavelengths required in an f-to-2f self-referencing interferometer. Our experimental results indicate the possibility of achieving an offset-frequency-locked frequency comb with the phase/intensity-modulated laser.
Li, Xiaohui; Wu, Kan; Sun, Zhipei; Meng, Bo; Wang, Yonggang; Wang, Yishan; Yu, Xuechao; Yu, Xia; Zhang, Ying; Shum, Perry Ping; Wang, Qi Jie
2016-04-29
Low phase noise mode-locked fiber laser finds important applications in telecommunication, ultrafast sciences, material science, and biology, etc. In this paper, two types of carbon nano-materials, i.e. single-wall carbon nanotube (SWNT) and graphene oxide (GO), are investigated as efficient saturable absorbers (SAs) to achieve low phase noise mode-locked fiber lasers. Various properties of these wall-paper SAs, such as saturable intensity, optical absorption and degree of purity, are found to be key factors determining the performance of the ultrafast pulses. Reduced-noise femtosecond fiber lasers based on such carbon-based SAs are experimentally demonstrated, for which the phase noise has been reduced by more than 10 dB for SWNT SAs and 8 dB for GO SAs at 10 kHz. To the best of our knowledge, this is the first investigation on the relationship between different carbon material based SAs and the phase noise of mode-locked lasers. This work paves the way to generate high-quality low phase noise ultrashort pulses in passively mode-locked fiber lasers.
Lu, Guo-Wei; Albuquerque, André; Puttnam, Benjamin J; Sakamoto, Takahide; Drummond, Miguel; Nogueira, Rogério; Kanno, Atsushi; Shinada, Satoshi; Wada, Naoya; Kawanishi, Tetsuya
2016-02-22
An important challenge for implementing optical signal processing functions such as wavelength conversion or wavelength data exchange (WDE) is to avoid the introduction of linear and nonlinear phase noise in the subsystem. This is particularly important for phase noise sensitive, high-order quadrature-amplitude modulation (QAM) signals. In this paper, we propose and experimentally demonstrate an optical data exchange scheme through cascaded 2nd-order nonlinearities in periodically-poled lithium niobate (PPLN) waveguides using coherent pumping. The proposed coherent pumping scheme enables noise from the coherent pumps to be cancelled out in the swapped data after WDE, even with broad linewidth distributed feedback (DFB) pump lasers. Hence, this scheme allows phase noise tolerant processing functions, enabling the low-cost implementation of WDE for high-order QAM signals. We experimentally demonstrate WDEs between 10-Gbaud 4QAM (4QAM) signal and 12.5-Gbaud 4QAM (16QAM) signal with 3.5-MHz linewidth DFB pump lasers and 50-GHz channel spacing. Error-free operation is observed for the swapped QAM signals with coherent DFB pumping whilst use of free-running DFB pumps leads to visible error floors and unrecoverable phase errors. The phase noise cancellation in the coherent pump scheme is further confirmed by study of the recovered carrier phase of the converted signals. In addition to pump phase noise, the influence of crosstalk caused by the finite extinction ratio in WDE is also experimentally investigated for the swapped QAM signals.
吕桂华; 周耀华; 李和战; 周超英
2012-01-01
Most frequency reference distribution amplification products in the domestic market don't meet requirements of the space TT& C systems on low phase noise specifications. This paper presents design of a low phase noise frequency reference distribution amplifier based on a two-level amplifier circuit structure using MAX4104 as a low phase noise gain amplifier and using LMH6609 as a strong driver distribution amplifier. In addition, advanced PCB design technology and effective noise suppression measures are used to get low phase noise frequency output from the distribution amplifier. Finally, validation of the design is given. Products of the design have already been successfully used in the frequency and time subsystems of satellite ground control systems and engineering applications show that the design meets the requirements of space TT& C systems and weaponry test systems.%随着测控试验系统对低相位噪声频标指标要求的不断提高,国内市场上的绝大部分相关产品已无法满足要求.本文给出一种低相位噪声频标分配放大器的设计实例,实例采用基于MAX4104增益放大和LMH6609分配放大的2级放大电路结构,充分利用MAX4104的低相位噪声放大特性和LMH6609的大电流驱动分配特性,同时采用先进的PCB(印制电路板)设计技术和有效的电路噪声抑制手段,实现了频标的低相位噪声分配放大输出.最后对实例设计进行了验证分析.本设计相关产品已广泛应用于卫星地面测控系统的时频分系统中,实践证明设计指标满足航天测控和武器试验用户的要求.
Several methods applied to measuring residual stress in a known specimen
Prime, M.B.; Rangaswamy, P.; Daymond, M.R.; Abelin, T.G.
1998-09-01
In this study, a beam with a precisely known residual stress distribution provided a unique experimental opportunity. A plastically bent beam was carefully prepared in order to provide a specimen with a known residual stress profile. 21Cr-6Ni-9Mn austenitic stainless steel was obtained as 43 mm square forged stock. Several methods were used to determine the residual stresses, and the results were compared to the known values. Some subtleties of applying the various methods were exposed.
Synchrotron strain scanning for residual stress measurement in cold-drawn steel rods
Ruiz Hervías, Jesús; Atienza Riera, José Miguel; Elices Calafat, Manuel
2011-01-01
Cold-drawn steel rods and wires retain significant residual stresses as a consequence of the manufacturing process. These residual stresses are known to be detrimental for the mechanical properties of the wires and their durability in aggressive environments. Steel makers are aware of the problem and have developed post-drawing processes to try and reduce the residual stresses on the wires. The present authors have studied this problem for a number of years and have performed a detailed chara...
Rapid measurement of residual dipolar couplings for fast fold elucidation of proteins
Rasia, Rodolfo M. [Jean-Pierre Ebel CNRS/CEA/UJF, Institut de Biologie Structurale (France); Lescop, Ewen [CNRS, Institut de Chimie des Substances Naturelles (France); Palatnik, Javier F. [Universidad Nacional de Rosario, Instituto de Biologia Molecular y Celular de Rosario, Facultad de Ciencias Bioquimicas y Farmaceuticas (Argentina); Boisbouvier, Jerome, E-mail: jerome.boisbouvier@ibs.fr; Brutscher, Bernhard, E-mail: Bernhard.brutscher@ibs.fr [Jean-Pierre Ebel CNRS/CEA/UJF, Institut de Biologie Structurale (France)
2011-11-15
It has been demonstrated that protein folds can be determined using appropriate computational protocols with NMR chemical shifts as the sole source of experimental restraints. While such approaches are very promising they still suffer from low convergence resulting in long computation times to achieve accurate results. Here we present a suite of time- and sensitivity optimized NMR experiments for rapid measurement of up to six RDCs per residue. Including such an RDC data set, measured in less than 24 h on a single aligned protein sample, greatly improves convergence of the Rosetta-NMR protocol, allowing for overnight fold calculation of small proteins. We demonstrate the performance of our fast fold calculation approach for ubiquitin as a test case, and for two RNA-binding domains of the plant protein HYL1. Structure calculations based on simulated RDC data highlight the importance of an accurate and precise set of several complementary RDCs as additional input restraints for high-quality de novo structure determination.
Zhu, Jianguo; Xie, Huimin; Hu, Zhenxing; Chen, Pengwan; Zhang, Qingming
2012-09-01
A plasma-sprayed thermal barrier coating (TBC) was deposited on a stainless steel substrate. The residual stresses were firstly measured by moiré interferometry combined with a cutting relaxation method. The fringe patterns in the cross-section of the specimen clearly demonstrate the deformation caused by the residual stress in thermal spray coatings. However, restricted by the sensitivity of moiré interferometry, there are few fringes in the top coat, and large errors may exist in evaluating the residual stress in the top coat. Then, the nanoindentation technique was used to estimate the residual stresses across the coating thickness. The stress/depth profile shows that the process-induced stresses after thermal spray are compressive in the top coat and a tendency to a more compressive state toward the interface. In addition, the stress gradient in the substrate is nonlinear, and tensile and compressive stresses appear simultaneously for self-equilibrium in the cross-section.
Ahmad, Bilal; Fitzpatrick, Michael E.
2016-01-01
The contour method of residual stress measurement relies on the careful application of wire electro-discharge machining (WEDM) for the cutting stage. Changes in material removal rates during the cut lead to errors in the final calculated values of residual stress. In this study, WEDM cutting parameters have been explored to identify the optimum conditions for contour method residual stress measurements. The influence of machine parameters on the surface roughness and cutting artifacts in the contour cut is discussed. It has been identified that the critical parameter in improving the surface finish is the spark pulse duration. A typical cutting artifact and its impact on measured stress values have been identified and demonstrated for a contour cut in a welded marine steel. A procedure is presented to correct contour displacement data from the influence of WEDM cutting artifacts, and is demonstrated on the correction of a measured weld residual stress. The corrected contour method improved the residual stress magnitude up to 150 MPa. The corrected contour method results were validated by X-ray diffraction, incremental center hole drilling, and neutron diffraction.
Lin, Qinhao; Zhang, Guohua; Peng, Long; Bi, Xinhui; Wang, Xinming; Brechtel, Fred J.; Li, Mei; Chen, Duohong; Peng, Ping'an; Sheng, Guoying; Zhou, Zhen
2017-07-01
To investigate how atmospheric aerosol particles interact with chemical composition of cloud droplets, a ground-based counterflow virtual impactor (GCVI) coupled with a real-time single-particle aerosol mass spectrometer (SPAMS) was used to assess the chemical composition and mixing state of individual cloud residue particles in the Nanling Mountains (1690 m a. s. l. ), southern China, in January 2016. The cloud residues were classified into nine particle types: aged elemental carbon (EC), potassium-rich (K-rich), amine, dust, Pb, Fe, organic carbon (OC), sodium-rich (Na-rich) and Other. The largest fraction of the total cloud residues was the aged EC type (49.3 %), followed by the K-rich type (33.9 %). Abundant aged EC cloud residues that mixed internally with inorganic salts were found in air masses from northerly polluted areas. The number fraction (NF) of the K-rich cloud residues increased within southwesterly air masses from fire activities in Southeast Asia. When air masses changed from northerly polluted areas to southwesterly ocean and livestock areas, the amine particles increased from 0.2 to 15.1 % of the total cloud residues. The dust, Fe, Pb, Na-rich and OC particle types had a low contribution (0.5-4.1 %) to the total cloud residues. Higher fraction of nitrate (88-89 %) was found in the dust and Na-rich cloud residues relative to sulfate (41-42 %) and ammonium (15-23 %). Higher intensity of nitrate was found in the cloud residues relative to the ambient particles. Compared with nonactivated particles, nitrate intensity decreased in all cloud residues except for dust type. To our knowledge, this study is the first report on in situ observation of the chemical composition and mixing state of individual cloud residue particles in China.
Design of Low Phase Noise SIPC based Complementary LC-QVCO for IEEE 802.11a Application
Harikrishnan Ramiah
2008-01-01
Full Text Available The paper presents the design of a source injection parallel coupled (SIPC quadrature voltage controlled oscillator (QVCO, realized in a complementary architecture, which is usually preferred in low-power applications as it exploits 50% bias current reduction with double efficiency compared to the structure with single coupled, when operating in the current-limited regime. A stacked spiral inductor exhibiting a Q factor of 5.8, with pMOS based depletion mode varactor of 32% in tuning range, corresponding to 3.2-3.6GHz of tuning frequency, is implemented in 0.18m CMOS technology. The phase noise of the SIPC QVCO architecture simulated at 1MHz of offset frequency is indicated to be -114.3dBc/Hz, while dissipating 11.0mW of core circuit power.
Ma, Yonghua; Liu, Hongjun; Sun, Qibing; Huang, Nan; Wang, Zhaolu
2016-04-20
We use a vector phase sensitive amplification (PSA) scheme, which can eliminate the inherent phase noise (PN) to amplitude noise (AN) conversion in a conventional PSA process. A dispersion-engineered silicon strip waveguide is used to investigate the vector PSA scheme at the telecom wavelengths. The phase-dependent gain and phase-to-phase transfer functions as well as constellation diagram at different signal polarization states (SPSs) are numerically analyzed. It is found that the PN to AN conversion is completely suppressed when the SPS is identical to one of the pump polarization states. Moreover, the binary phase shift keying signal is regenerated by the proposed vector PSA scheme, and the error vector magnitude is calculated to assess the regeneration capacity. Our results have potential application in all-optical signal processing.
Yi, Xingwen; Xu, Bo; Zhang, Jing; Lin, Yun; Qiu, Kun
2014-12-15
Digital coherent superposition (DCS) of optical OFDM subcarrier pairs with Hermitian symmetry can reduce the inter-carrier-interference (ICI) noise resulted from phase noise. In this paper, we show two different implementations of DCS-OFDM that have the same performance in the presence of laser phase noise. We complete the theoretical calculation on ICI reduction by using the model of pure Wiener phase noise. By Taylor expansion of the ICI, we show that the ICI power is cancelled to the second order by DCS. The fourth order term is further derived out and only decided by the ratio of laser linewidth to OFDM subcarrier symbol rate, which can greatly simplify the system design. Finally, we verify our theoretical calculations in simulations and use the analytical results to predict the system performance. DCS-OFDM is expected to be beneficial to certain optical fiber transmissions.
Sobreviela, Guillermo; Riverola, Martin; Canals, Francesc; Del Monte, Arantxa; Beumala, Nuria
2017-02-13
In this paper, the phase noise of a 24-MHz CMOSMEMS oscillator with zero-level vacuum package is studied. We characterize and analyze the nonlinear regime of each one of the modules that compose the oscillator (CMOS sustaining-amplifier and MEMS resonator). As we show, the presented resonator exhibits a high nonlinear behavior. Such fact is exploited as a mechanism to stabilize the oscillation amplitude, allowing to maintain the sustaining-amplifier working in the linear regime. Consequently, the nonlinear resonator becomes the main closeto- carrier phase noise source. The sustaining amplifier, which functions as a phase shifter, was developed such that MEMS operation point optimization could be achieved without an increase in circuitry modules. Therefore, the system saves on area and power, and is able to improve the phase noise 26 dBc/Hz (@1 kHz carrier frequency offset).
Cheng, Jingchi; Tang, Ming; Fu, Songnian; Shum, Perry Ping; Liu, Deming
2013-04-01
We show for the first time, to the best of our knowledge, that, in a coherent communication system that employs a phase-shift-keying signal and Raman amplification, besides the pump relative intensity noise (RIN) transfer to the amplitude, the signal's phase will also be affected by pump RIN through the pump-signal cross-phase modulation. Although the average pump power induced linear phase change can be compensated for by the phase-correction algorithm, a relative phase noise (RPN) parameter has been found to characterize pump RIN induced stochastic phase noise. This extra phase noise brings non-negligible system impairments in terms of the Q-factor penalty. The calculation shows that copumping leads to much more stringent requirements to pump RIN, and relatively larger fiber dispersion helps to suppress the RPN induced impairment. A higher-order phase-shift keying (PSK) signal is less tolerant to noise than a lower-order PSK.
Criado, A. R.; Acedo, P.; Carpintero, G.
2012-01-01
A Continuous Wave (CW) sub-THz photonic synthesis setup based on a single Passively Mode-Locked Laser Diode (PMLLD) acting as a monolithic Optical Frequency Comb Generator (OFCG) and highly selective optical filtering has been implemented to evaluate the phase noise performance of the generated sub......-THz signals. The analysis of the synthesized sub-THz signals up to 120 GHz gives as a result an effective reduction of the electrical linewidth when compared to direct harmonic generation that begins at 50 GHz and becomes greater as the frequency increases. The phase noise reduction offered by the setup......, along with its integration potential, cost and bandwidth, make it a promising candidate to the development of an integrated and high performance low phase noise local oscillator in the sub-THz range....
Huanhuan, Tian; Zhiqiang, Li; Pufeng, Chen; Rufei, Wu; Haiying, Zhang
2010-12-01
A monolithic low-power and low-phase-noise digitally controlled oscillator (DCO) based on a symmetric spiral inductor with center-tap and novel capacitor bank was implemented in a 0.18 μm CMOS process with six metal layers. A third new way to change capacitance is proposed and implemented in this work. Results show that the phase noise at 1 MHz offset frequency is below -122.5 dBc/Hz while drawing a current of only 4.8 mA from a 1.8 V supply. Also, the DCO can work at low supply voltage conditions with a 1.6 V power supply and 4.1 mA supply current for the DCO's core circuit, achieving a phase-noise of -21.5 dBc/Hz at offset of 1 MHz. It demonstrates that the supply pushing of DCO is less than 10 MHz/V.
A Way to Measure the Residual Flow in the Lim Fjord
Larsen, Torben
The Lim fjord in Denmark has two connections to the open sea. Therefore the residual flow through the Lim fjord is an important parameter in relation to salinity and concentration on nutrients. It is described how it has been possible to determine the residual flow from the observation...
Measurement of the fluorescence of crop residues: A tool for controlling soil erosion
Daughtry, C. S. T.; Mcmurtrey, J. E., III; Chappelle, E. W.; Hunter, W. J.
1994-01-01
Management of crop residues, the portion of a crop left in the field after harvest, is an important conservation practice for minimizing soil erosion and for improving water quality. Quantification of crop residue cover is required to evaluate the effectiveness of conservation tillage practices. Methods are needed to quantify residue cover that are rapid, accurate, and objective. The fluorescence of crop residue was found to be a broadband phenomenon with emission maxima at 420 to 495 nm for excitations of 350 to 420 nm. Soils had low intensity broadband emissions over the 400 to 690 nm region for excitations of 300 to 600 nm. The range of relative fluorescence intensities for the crop residues was much greater than the fluorescence observed of the soils. As the crop residues decompose their blue fluorescence values approach the fluorescence of the soil. Fluorescence techniques are concluded to be less ambiguous and better suited for discriminating crop residues and soils than reflectance methods. If properly implemented, fluorescence techniques can be used to quantify, not only crop residue cover, but also photosynthetic efficiency in the field.
亚敏; 戴福隆; 谢惠民; 吕坚
2003-01-01
Hole-drilling method is one of the most convenient methods for engineering residual ment data, hole-drilling technique can be used to solve non-uniform residual stress problems, both (MIIHD) for non-uniform residual stress measurement is introduced. Three dimensional finite element model is constructed by ABAQUS to obtain the coefficients for the residual stress calculation.An experimental system including real-time measurement, automatic data processing and residual stresses calculation is established. Two applications for non-uniform in-depth residual stress of surface nanocrystalline material and non-uniform in-plane residual stress of friction stir welding are presented.Experimental results show that MIIHD is effective for both non-uniform in-depth and in-plane residual stress measurements.
Quemada, C.; Adin, I.; Bistue, G.; Berenguer, R.; Mendizabal, J.
2005-06-01
A 3.3V, fully integrated 3.2-GHz voltage-controlled oscillator (VCO) is designed in a 0.18μm CMOS technology for the IEE 802.11a/HiperLAN WLAN standard for the UNII band from 5.15 to 5.35 GHz. The VCO is tunable between 2.85 GHz and 3.31 GHz. NMOS architecture with self-biasing current of the tank source is chosen. A startup circuit has been employed to avoid zero initial current. Current variation is lower than 1% for voltage supply variations of 10%. The use of a self-biasing current source in the tank provides a greater safety in the transconductance value and allows running along more extreme point operation The designed VCO displays a phase noise and output power of -98dBc/Hz (at 100 KHz offset frequency) and 0dBm respectively. This phase noise has been obtained with inductors of 2.2nH and quality factor of 12 at 3.2 GHz, and P-N junction varactors whose quality factor is estimated to exceed 40 at 3.2 GHz. These passive components have been fabricated, measured and modeled previously. The core of the VCO consumes 33mW DC power.
G. Lesins
2009-03-01
Full Text Available Ice crystals, also known as diamond dust, are suspended in the boundary layer air under clear sky conditions during most of the Arctic winter in Northern Canada. Occasionally ice crystal events can produce significantly thick layers with optical depths in excess of 2.0 even in the absence of liquid water clouds. Four case studies of high optical depth ice crystal events at Eureka in the Nunavut Territory of Canada during the winter of 2006/07 are presented. They show that the measured ice crystal surface infrared downward radiative forcing ranged from 8 to 36 W m^{−2} in the wavelength band from 5.6 to 20 μm for 532 nm optical depths ranging from 0.2 to 1.7. MODIS infrared and visible images and the operational radiosonde wind profile were used to show that these high optical depth events were caused by surface snow being blown off 600 to 800 m high mountain ridges about 20 to 30 km North-West of Eureka and advected by the winds towards Eureka as they settled towards the ground within the highly stable boundary layer. This work presents the first study that demonstrates the important role that surrounding topography plays in determining the occurrence of high optical depth ice crystal events from residual blowing snow that becomes a source of boundary layer ice crystals distinct from the classical diamond dust phenomenon.
Studies of residual stress measurement and analysis techniques for a PWR dissimilar weld joint
Ogawa, Naoki, E-mail: naoki2_ogawa@mhi.co.jp [Mitsubishi Heavy Industries, Ltd., 2-1-1, Shinhama, Arai-cho, Takasago 676-8686 (Japan); Muroya, Itaru; Iwamoto, Youichi; Ohta, Takahiro; Ochi, Mayumi; Hojo, Kiminobu [Mitsubishi Heavy Industries, Ltd., 2-1-1, Shinhama, Arai-cho, Takasago 676-8686 (Japan); Ogawa, Kazuo [Japan Nuclear Energy Safety Organization, 3-17-1, Toranomon, Minato-ku, Tokyo 105-0001 (Japan)
2012-02-15
For evaluation of the PWSCC crack propagation behavior, a test model was produced using the same fabrication process of Japanese PWR plants and the stress distribution change was measured during a fabrication process such as a hydrostatic test, welding a main coolant pipe to the stainless steel safe end and an operation condition test. For confirmation of validity of the numerical estimation method of the stress distribution, FE analysis was performed to calculate the stress distributions for each fabrication process. From the validation procedure, a standard residual stress evaluation method was established. Furthermore for consideration of characteristics of PWSCC's propagation behavior of the dissimilar welding joint of the safe end nozzles, the influence coefficients at the deepest point for the stress intensity factors of axial cracks with large aspect ratio a/c (crack depth/half of surface crack length) was prepared. The crack shape was assumed a rectangular shape and the stress intensity factors at the deepest point of the crack were calculated with change of crack depth using FE analysis. By using these stress distribution and influence coefficients, a behavior of a PWSCC crack propagation at the safe end nozzles can be estimated easily and rationally.
Velicheti, Dheeraj; Nagy, Peter B.; Hassan, Waled
2017-02-01
We investigated the feasibility of residual stress assessment based on Hall coefficient measurements in precipitation hardened IN718 nickel-base superalloy. As a first step, we studied the influence of microstructural variations on the galvanomagnetic properties of IN718 nickel-base superalloy. We found that the Hall coefficient of IN718 increases from ≈ 8.0×10-11 m3/C in its fully annealed state of 15 HRC Rockwell hardness to ≈ 9.4×10-11 m3/C in its fully hardened state of 45 HRC. We also studied the influence of cold work, i.e., plastic deformation, at room temperature and found that cold work had negligible effect on the Hall coefficient of fully annealed IN718, but significantly reduced it in hardened states of the material. For example, measurements conducted on fully hardened IN718 specimens showed that the Hall coefficient decreased more or less linearly with cold work from its peak value of ≈ 9.4×10-11 m3/C in its intact state to ≈ 9.0×10-11 m3/C in its most deformed state of 22% plastic strain. We also studied the influence of applied stress and found that elastic strain significantly increases the Hall coefficient of IN718 regardless of the state of hardening. The relative sensitivity of the Hall coefficient to elastic strain was measured as a unitless gauge factor K that is defined as the ratio of the relative change of the Hall coefficient ΔRH/RH divided by the axial strain ɛ = σ/E, where σ is the applied uniaxial stress and E is the Young's modulus of the material. We determined that the galvanomagnetic gauge factor of IN718 is κ ≈ 2.6 - 2.9 depending on the hardness level. Besides the fairly high value of the gauge factor, it is important that it is positive, which means that compressive stress in surface-treated components decreases the Hall coefficient in a similar way as plastic deformation does, therefore the unfortunate cancellation that occurs in fully hardened IN718 in the case of electric conductivity measurements will not
Common mode noise rejection properties of amplitude and phase noise in a heterodyne interferometer
Hechenblaikner, Gerald
2013-01-01
High precision metrology systems based on heterodyne interferometry can measure position and attitude of objects to accuracies of picometer and nanorad, respectively. A frequently found feature of the general system design is the subtraction of a reference phase from the phase of the position interferometer, which suppresses low frequency common mode amplitude and phase fluctuations occurring in volatile optical path sections shared by both, the position and reference interferometer. Spectral components of the noise at frequencies around or higher than the heterodyne frequency, however, are generally transmitted into the measurement band and may limit the measurement accuracy. Detailed analytical calculations complemented with Monte Carlo simulations show that high frequency noise components may also be entirely suppressed, depending on the relative difference of measurement and reference phase, which may be exploited by corresponding design provisions. Whilst these results are applicable to any heterodyne in...
Chen, Q.; Mao, W. G.; Zhou, Y. C.; Lu, C.
2010-09-01
Subjected to thermal cycling, the apparent Young's modulus of air plasma-sprayed (APS) 8 wt.% Y 2O 3-stabilized ZrO 2 (8YSZ) thermal barrier coatings (TBCs) was measured by nanoindentation. Owing to the effects of sintering and porous microstructure, the apparent Young's modulus follows a Weibull distribution and changes from 50 to 93 GPa with an increase of thermal cycling. The evolution of residual stresses in the top coating of an 8YSZ TBC system was determined by X-ray diffraction (XRD). The residual stresses derived from the XRD data are well consistent with that obtained by the Vickers indention. It is shown that the evolution of Young's modulus plays an important role in improving the measurement precision of residual stresses in TBCs by XRD.
A robust method to measure residual stress in micro-structure
KANG Yi-lan; QIU Wei; LEI Zhen-kun
2007-01-01
An experimental investigation on the residual stress in porous silicon micro-structure by means of micro-Raman spectroscopy is presented. It is shown by detecting the Raman peak shifts on the surfaces and cross-sections of electrochemical etched porous silicon samples with different porosities that serious residual stresses distribute complicatedly within the whole porous silicon structure. It is proved that micro-Raman spectroscopy is an effective method for residual stress testing on the micro-structures applied in optoelectronics and microelectronics.
Measurement and Analysis on Hardness and Residual Stress of Heavy Forging after Heat Treatment
无
2002-01-01
The hardness and residual stress in the forging for cold roller during low temperature tempering, and the relationship of residual stress and cooling temperature of high temperature tempering for heavy forgings were studied. The stress relaxation constant at low temperature tempering and the elasto-plastisity inversion temperature at high temperature tempering were found. The results are of great importance to determine rational tempering cooling process of heavy forgings.
Common mode noise rejection properties of amplitude and phase noise in a heterodyne interferometer.
Hechenblaikner, Gerald
2013-05-01
High precision metrology systems based on heterodyne interferometry can measure the position and attitude of objects to accuracies of picometer and nanorad, respectively. A frequently found feature of the general system design is the subtraction of a reference phase from the phase of the position interferometer, which suppresses low frequency common mode amplitude and phase fluctuations occurring in volatile optical path sections shared by both the position and reference interferometer. Spectral components of the noise at frequencies around or higher than the heterodyne frequency, however, are generally transmitted into the measurement band and may limit the measurement accuracy. Detailed analytical calculations complemented with Monte Carlo simulations show that high frequency noise components may also be entirely suppressed, depending on the relative difference of measurement and reference phase, which may be exploited by corresponding design provisions. While these results are applicable to any heterodyne interferometer with certain design characteristics, specific calculations and related discussions are given for the example of the optical metrology system of the LISA Pathfinder mission to space.
Subtraction of temperature induced phase noise in the LISA frequency band
Nofrarias, M; Karnesis, N; Garcia, A F; Hewitson, M; Heinzel, G; Danzmann, K
2013-01-01
Temperature fluctuations are expected to be one of the limiting factors for gravitational wave detectors in the very low frequency range. Here we report the characterisation of this noise source in the LISA Pathfinder optical bench and propose a method to remove its contribution from the data. Our results show that temperature fluctuations are indeed limiting our measurement below one millihertz, and that their subtraction leads to a factor 5.6 (15 dB) reduction in the noise level at the lower end of the LISA measurement band 10^{-4} Hz, which increases to 20.2 (26 dB) at even lower frequencies, i.e., 1.5x10^{-5} Hz. The method presented here can be applied to the subtraction of other noise sources in gravitational wave detectors in the general situation where multiple sensors are used to characterise the noise source.
Rivera, David; Wirz, Richard E.; Ghoniem, Nasr M.
2017-04-01
The thermomechanical damage and residual stresses in plasma-facing materials operating at high heat flux are experimentally investigated. Materials with micro-surfaces are found to be more resilient, when exposed to cyclic high heat flux generated by an arc-jet plasma. An experimental facility, dedicated to High Energy Flux Testing (HEFTY), is developed for testing cyclic heat flux in excess of 10 MW/m2. We show that plastic deformation and subsequent fracture of the surface can be controlled by sample cooling. We demonstrate that W surfaces with micro-pillar type surface architecture have significantly reduced residual thermal stresses after plasma exposure, as compared to those with flat surfaces. X-ray diffraction (XRD) spectra of the W-(110) peak reveal that broadening of the Full Width at Half Maximum (FWHM) for micro-engineered samples is substantially smaller than corresponding flat surfaces. Spectral shifts of XRD signals indicate that residual stresses due to plasma exposure of micro-engineered surfaces build up in the first few cycles of exposure. Subsequent cyclic plasma heat loading is shown to anneal out most of the built-up residual stresses in micro-engineered surfaces. These findings are consistent with relaxation of residual thermal stresses in surfaces with micro-engineered features. The initial residual stress state of highly polished flat W samples is compressive (≈ -1.3 GPa). After exposure to 50 plasma cycles, the surface stress relaxes to -1.0 GPa. Micro-engineered samples exposed to the same thermal cycling show that the initial residual stress state is compressive at (- 250 MPa), and remains largely unchanged after plasma exposure.
An Ultra-Low Phase Noise Class-F 2 CMOS Oscillator With 191 dBc/Hz FoM and Long-Term Reliability
Babaie, M.; Staszewski, R.B.
2015-01-01
In this paper, we propose a new class of operation of an RF oscillator that minimizes its phase noise. The main idea is to enforce a clipped voltage waveform around the LC tank by increasing the second-harmonic of fundamental oscillation voltage through an additional impedance peak, thus giving rise
UHF RFID系统相位噪声的研究与仿真%Study and Simulation of Phase Noise for UHF RFID System
张俊; 何怡刚; 侯周国; 代扬
2009-01-01
This paper introduces an analysis method of phase noise requirements on a local oscillator for a UHF Radio Frequency Identification (RFID) system. In general case, phase noise requirements are derived considering a reciprocal mixing with an interference signal. In UHF RFID system, the same oscillator is used for the transmitted signal and the Local Oscillator(LO), range correlation phenomenon effects the phase noise requirements. This paper derives new phase noise equation considering the range correlation effect on the RFID system and a simulation is done. Simulation results for UHF RFID system show that range correlation effect is the important factor in RFID system design.%介绍一种UHF RFID系统席:振相位噪声性能分析的方法.在一般情况下,相位噪卢是频埤c源信号与干扰信号的相互混频.在UHFRFID系统中发射信号与本振信号使用的是相同的振荡器,距离相关现象会影响相位噪声性能的指标要求.在考虑到距离相关影响的前提下重新得到RFID系统的新的相位噪卢方程并进行仿真,仿真结果表明距离相关是UHF RFID系统没计中的重要囚素.
Bender, Florian; Mohler, Rachel E; Ricco, Antonio J; Josse, Fabien
2014-11-18
The present work investigates a compact sensor system that provides rapid, real-time, in situ measurements of the identities and concentrations of aromatic hydrocarbons at parts-per-billion concentrations in water through the combined use of kinetic and thermodynamic response parameters. The system uses shear-horizontal surface acoustic wave (SH-SAW) sensors operating directly in the liquid phase. The 103 MHz SAW sensors are coated with thin sorbent polymer films to provide the appropriate limits of detection as well as partial selectivity for the analytes of interest, the BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), which are common indicators of fuel and oil accidental releases in groundwater. Particular emphasis is placed on benzene, a known carcinogen and the most challenging BTEX analyte with regard to both regulated levels and its solubility properties. To demonstrate the identification and quantification of individual compounds in multicomponent aqueous samples, responses to binary mixtures of benzene with toluene as well as ethylbenzene were characterized at concentrations below 1 ppm (1 mg/L). The use of both thermodynamic and kinetic (i.e., steady-state and transient) responses from a single polymer-coated SH-SAW sensor enabled identification and quantification of the two BTEX compounds in binary mixtures in aqueous solution. The signal-to-noise ratio was improved, resulting in lower limits of detection and improved identification at low concentrations, by designing and implementing a type of multielectrode transducer pattern, not previously reported for chemical sensor applications. The design significantly reduces signal distortion and root-mean-square (RMS) phase noise by minimizing acoustic wave reflections from electrode edges, thus enabling limits of detection for BTEX analytes of 9-83 ppb (calculated from RMS noise); concentrations of benzene in water as low as ~100 ppb were measured directly. Reliable quantification of BTEX
Thermo-elastic induced phase noise in the LISA Pathfinder spacecraft
Gibert, F; Nofrarias, M; Karnesis, N; Gesa, L.; Martín, V.; Mateos, I; Lobo, A; Flatscher, R.; Gerardi, D; Burkhardt, J.; Gerndt, R.; Robertson, D; Ward, H; McNamara, P; Guzman, F.
2014-01-01
During the On-Station Thermal Test campaign of the LISA Pathfinder the data and diagnostics subsystem was tested in nearly space conditions for the first time after integration in the satellite. The results showed the compliance of the temperature measurement system, obtaining temperature noise around $10^{-4}\\,{\\rm K}\\, {\\rm Hz}^{-1/2}$ in the frequency band of $1-30\\;{\\rm mHz}$. In addition, controlled injection of heat signals to the suspension struts anchoring the LISA Technology Package ...
Mordaunt, Catriona J.; Gevao, Bondi; Jones, Kevin C.; Semple, Kirk T
2005-01-01
Six major use pesticides (Atrazine, Dicamba, Isoproturon, Lindane, Paraquat and Trifluralin) with differing physico-chemical properties were evaluated for the significance of 'bound' or non extractable residue formation. Investigations were carried out in purpose-built microcosms where mineralization, volatilisation, 'soil water' extractable and organic solvent extractable residues could be quantified. Extractable residues were defined as those accessible by sequential extraction where the solvent used became increasingly non-polar. Dichloromethane was the 'harshest' solvent used at the end of the sequential extraction procedure. {sup 14}C-labelled volatilised and {sup 14}CO{sub 2} fractions were trapped on exit from the microcosm. The pesticides were categorised into 3 classes based on their behaviour. (i) Type A (Atrazine, Lindane and Trifluralin) in which ring degradation was limited as was the formation of non-extractable residues; the remainder of the {sup 14}C-activity was found in the extractable fraction. (ii) Type B (Dicamba and Isoproturon) in which approximately 25% of the {sup 14}C-activity was mineralised and a large portion was found in the non-extractable fraction after 91 days. Finally, Type C (Paraquat) in which almost all of the {sup 14}C-activity was quickly incorporated into the non-extractable fraction. The implications of the data are discussed, with respect to the variability and significance of regulatory aspects of non-extractable residues.
Zhang, M; Roberts, C
2000-11-01
Interface pressures and shear stresses between a below-knee residual limb and prosthetic socket predicted using finite element analyses were compared with experimental measurements. A three-dimensional nonlinear finite element model, based on actual residual geometry and incorporating PTB socket rectification and interfacial friction/slip conditions, was developed to predict the stress distribution. A system for measuring pressures and bi-axial shear stresses was used to measure the stresses in the PTB socket of a trans-tibial amputee. The FE-predicted results indicated that the peak pressure of 226 kPa occurred at the patellar tendon area and the peak shear stress of 50 kPa at the anterolateral tibia area. Quantitatively, FE-predicted pressures were 11%, on average, lower than those measured by triaxial transducers placed at all the measurement sites. Because friction/slip conditions between the residual limb and socket liner were taken into consideration by using interface elements in the FE model, the directions and magnitudes of shear stresses match well between the FE prediction and clinical measurements. The results suggest that the nonlinear mechanical properties of soft tissues and dynamic effects during gait should be addressed in future work.
Knowles, C. R.
2012-11-01
Full Text Available Selective laser melting (SLM of Ti-6Al-4V has significant potential in the aerospace and biotechnology industries. SLM employs a focused laser beam to melt successive layers of metallic powder into complex components. This process can result in the generation of high thermally-induced residual stresses. These residual stresses, together with micro-flaws/ pores from the inherent fabrication process, may lead to premature fatigue crack initiation and propagation at relatively low cyclic stresses. The hole-drilling strain gauge method was used to evaluate residual stresses within SLM Ti-6Al-4V specimens, with the intention of understanding the associated mechanisms for the successful application of SLM Ti-6Al-4V in industry.
Measurement of residual solvents in a drug substance by a purge-and-trap method.
Lakatos, Miklós
2008-08-05
The purge-and-trap (P&T) gas extraction method combined with gas chromatography was studied for its suitability for quantitative residual solvents determination in a water-soluble active pharmaceutical ingredient (API). Some analytical method performance characteristics were investigated, namely, the repeatability, the accuracy and the detection limit of determination. The results show that the P&T technique is--as expected--more sensitive than the static headspace, thus it can be used for the determination of residual solvents pertaining to the ICH Class 1 group. It was found that it could be an alternative sample preparation method besides the static headspace (HS) method.
Effect of phase noise on quantum correlations in Bose-Josephson junctions
Ferrini, G.; Minguzzi, A.; Hekking, F. W. J. [Universite Grenoble 1 and CNRS, Laboratoire de Physique et Modelisation des Milieux Condenses UMR5493, B.P. 166, F-38042 Grenoble (France); Spehner, D. [Universite Grenoble 1 and CNRS, Laboratoire de Physique et Modelisation des Milieux Condenses UMR5493, B.P. 166, F-38042 Grenoble (France); Universite Grenoble 1 and CNRS, Institut Fourier UMR5582, B.P. 74, F-38402 Saint Martin d' Heres (France)
2011-10-15
In a two-mode Bose-Josephson junction the dynamics induced by a sudden quench of the tunnel amplitude leads to the periodic formation of entangled states. For instance, squeezed states are formed at short times and macroscopic superpositions of phase states at later times. In atom interferometry, the two modes of the junction play the role of the two arms of a Mach-Zehnder interferometer; use of multiparticle entangled states allows the enhancement of phase sensitivity with respect to that obtained from uncorrelated atoms. Decoherence due to the presence of noise degrades quantum correlations between atoms, thus reducing phase sensitivity. We consider decoherence due to stochastic fluctuations of the energies of the two modes of the junction. We analyze its effect on squeezed states and macroscopic superpositions and calculate the squeezing parameter and the quantum Fisher information during the quenched dynamics. The latter quantity measures the amount of quantum correlations useful in interferometry. For moderate noise intensities, we show that it increases on time scales beyond the squeezing regime. This suggests multicomponent superpositions of phase states as interesting candidates for high-precision atom interferometry.
Lo, C. C. H.
2011-06-01
A new surface sensor probe comprising an angular array of Hall effect sensors has been developed for characterization of residual stresses in ferrous materials by means of stress-induced magnetic anisotropy measurements. The sensor probe applies a radially spreading ac magnetic field to a test sample, and detects stray fields in different directions simultaneously to determine the principal stress axes. In situ measurements were conducted on a annealed steel plate under four-point bending stresses to evaluate the probe performance. The ratio of stray field signals measured along and perpendicular to the stress axis varies linearly with the surface stress, indicating the possibility of characterizing residual stresses in ferrous components using the sensor array probe.
Fulton, J. P.; Wincheski, B.; Namkung, M.; Utrata, D.
1992-01-01
The magnetoacoustic measurement technique has been used successfully for residual stress measurements in laboratory samples. However, when used to field test samples with complex geometries, such as railroad wheels, the sensitivity of the method declines dramatically. It has been suggested that the decrease in performance may be due, in part, to an insufficient or nonuniform magnetic induction in the test sample. The purpose of this paper is to optimize the test conditions by using finite element modeling to predict the distribution of the induced bulk magnetization of railroad wheels. The results suggest that it is possible to obtain a sufficiently large and uniform bulk magnetization by altering the shape of the electromagnet used in the tests. Consequently, problems associated with bulk magnetization can be overcome, and should not prohibit the magnetoacoustic technique from being used to make residual stress measurements in railroad wheels. We begin by giving a brief overview of the magnetoacoustic technique as it applies to residual stress measurements of railroad wheels. We then define the finite element model used to predict the behavior of the current test configuration along with the nonlinear constitutive relations which we obtained experimentally through measurements on materials typically used to construct both railroad wheels and electromagnets. Finally, we show that by modifying the pole of the electromagnet it is possible to obtain a significantly more uniform bulk magnetization in the region of interest.
Matulionis, Arvydas
2013-07-01
The problems in the realm of nitride heterostructure field-effect transistors (HFETs) are discussed in terms of a novel fluctuation-dissipation-based approach impelled by a recent demonstration of strong correlation of hot-electron fluctuations with frequency performance and degradation of the devices. The correlation has its genesis in the dissipation of the LO-mode heat accumulated by the non-equilibrium longitudinal optical phonons (hot phonons) confined in the channel that hosts the high-density hot-electron gas subjected to a high electric field. The LO-mode heat causes additional scattering of hot electrons and facilitates defect formation in a different manner than the conventional heat contained mainly in the acoustic phonon mode. We treat the heat dissipation problem in terms of the hot-phonon lifetime responsible for the conversion of the non-migrant hot phonons into migrant acoustic modes and other vibrations. The lifetime is measured over a wide range of electron density and supplied electric power. The optimal conditions for the dissipation of the LO-mode heat are associated with the plasmon-assisted disintegration of hot phonons. Signatures of plasmons are experimentally resolved in fluctuations, dissipation, hot-electron transport, transistor frequency performance, transistor phase noise and transistor reliability. In particular, a slower degradation and a faster operation of GaN-based HFETs take place inside the electron density window where the resonant plasmon-assisted ultrafast dissipation of the LO-mode heat comes into play. A novel heterostructure design for the possible improvement of HFET performance is proposed, implemented and tested.
A wide-band low phase noise LC-tuned VCO with constant KVCO/ωosc for LTE PLL
黄继伟; 王志功; 李奎利; 李正平; 王永平
2012-01-01
A wideband LC-tuned voltage-controlled oscillator (LC-VCO) applied in LTE PLL frequency synthesizers with constant KVCO/ωosc is described,In order to minimize the loop bandwidth variations of PLL,a varactor array is proposed,which consists of a series of differential variable capacitor pairs and a series of single-pole double-throw (SPDT) switches to connect Vtune or VDD.The switches are controlled by switching bits.With this scheme,the ratio of KV =(6)Cvar/(6)Vtune and the capacitance value of the capacitor array maintains relatively constant; furthermore,the loop bandwidth of the PLL fluctuation is suppressed.The 3.2-4.6-GHz VCO for multi-band LTE PLL is fabricated in a 0.13-μm RF-CMOS process.The VCO exhibits a maximum variation of KVCO/ωosc of only ±4%.The VCO also exhibits a low phase-noise of-124 dBc/Hz at a 1-MHz offset frequency and a low current consumption of 18.0 mA with a 1.2-V power supply.
Christelle Garnier
2008-05-01
Full Text Available We address the problem of phase noise (PHN and carrier frequency offset (CFO mitigation in multicarrier receivers. In multicarrier systems, phase distortions cause two effects: the common phase error (CPE and the intercarrier interference (ICI which severely degrade the accuracy of the symbol detection stage. Here, we propose a non-pilot-aided scheme to jointly estimate PHN, CFO, and multicarrier signal in time domain. Unlike existing methods, non-pilot-based estimation is performed without any decision-directed scheme. Our approach to the problem is based on Bayesian estimation using sequential Monte Carlo filtering commonly referred to as particle filtering. The particle filter is efficiently implemented by combining the principles of the Rao-Blackwellization technique and an approximate optimal importance function for phase distortion sampling. Moreover, in order to fully benefit from time-domain processing, we propose a multicarrier signal model which includes the redundancy information induced by the cyclic prefix, thus leading to a significant performance improvement. Simulation results are provided in terms of bit error rate (BER and mean square error (MSE to illustrate the efficiency and the robustness of the proposed algorithm.
Phase noise in pulsed Doppler lidar and limitations on achievable single-shot velocity accuracy
Mcnicholl, P.; Alejandro, S.
1992-01-01
practical impact on lidar design parameters. In high SNR operation, for example, a lidar's efficiency in obtaining mean wind measurements is determined by its repetition rate and not pulse energy or average power. In addition, this variance puts a practical limit on the shot-to-shot hard target performance required of a lidar.
Wang, Xing; Morgan, Donna M; Wang, Gan; Mozier, Ned M
2012-02-01
Residual DNA (rDNA) is comprised of deoxyribonucleic acid (DNA) fragments and longer length molecules originating from the host organism that may be present in samples from recombinant biological processes. Although similar in basic structural base pair units, rDNA may exist in different sizes and physical forms. Interest in measuring rDNA in recombinant products is based primarily on demonstration of effective purification during manufacturing, but also on some hypothetical concerns that, in rare cases, depending on the host expression system, some DNA sequences may be potentially infectious or oncogenic (e.g., HIV virus and the Ras oncogene, respectively). Recent studies suggest that a sequence known as long interspersed nucleotide element-1 (LINE-1), widely distributed in the mammalian genome, is active as a retrotransposon that can be transcribed to RNA, reverse-transcribed into DNA and inserts into a new site in genome. This integration process could potentially disrupt critical gene functions or induce tumorigenesis in mammals. Genomic DNA from microbial sources, on the other hand, could add to risk of immunogenicity to the target recombinant protein being expressed, due to the high CpG content and unmethylated DNA sequence. For these and other reasons, it is necessary for manufacturers to show clearance of DNA throughout production processes and to confirm low levels in the final drug substance using an appropriately specific and quantitative analytical method. The heterogeneity of potential rDNA sequences that might be makes the testing of all potential analytes challenging. The most common methodology for rDNA quantitation used currently is real-time polymerase chain reaction (RT-PCR), a robust and proven technology. Like most rDNA quantitation methods, the specificity of RT-PCR is limited by the sequences to which the primers are directed. To address this, primase-based whole genome amplification is introduced herein. This paper will review the recent
Exclusion of measurements with excessive residuals (blunders) in estimating model parameters
Nikiforov, I I
2013-01-01
An adjustable algorithm of exclusion of conditional equations with excessive residuals is proposed. The criteria applied in the algorithm use variable exclusion limits which decrease as the number of equations goes down. The algorithm is easy to use, it possesses rapid convergence, minimal subjectivity, and high degree of generality.
Roelandts, T.; Batenburg, K.J.; Dekker, A.J. den; Sijbers, J.
2014-01-01
In this paper, we present the reconstructed residual error, which evaluates the quality of a given segmentation of a reconstructed image in tomography. This novel evaluation method, which is independent of the methods that were used to reconstruct and segment the image, is applicable to segmentation
Review of Agricultural Plastic Mulching and Its Residual Pollution and Prevention Measures In China
YAN Chang-rong
2014-04-01
Full Text Available Agricultural plastic film mulching is one of important technologies, but the plastic film pollution has been a serious issue for agri-cultural sustainable development in China. System analysis of this technique and its residue pollution and control ways have vital practicalsignificance for rational application of agricultural plastil film. In this paper, on the basis of our previous work,agricultural plastic filmmulching, its residue pollution and control technologies were concluded. Some important conclusions were found that, the amount of plasticfilm and mulching area had kept increasing with annual increasing rate about 8% since the 80s of the 20th century. From 1991 to 2011, thedensity of plastic film utilized increased 3-10 times, but it has very sharply different spatial pattern in different province. In general, the northand west China has high value, and the increase rate is also huge in the past 20 years. The crops of utilized mulching plastic film have extendedfrom cash crops to grain crops, and the order of crop area is followed by maize, vegetable, cotton, tobacco and peanut. The main functions ofmulching plastic film are keeping soil moisture and increasing soil temperature, against weeds and insect. At the same time, its side effectsappear with continuous utilization. The main problems are residues left in soil to destroy soil structure, impress soil permeability, impede seedgermination as well as water and nutrients uptaking, and block crop root system development. It has very serious pollution for the field utilizedplastic mulching film for long term. The residual amount in soil is about 71.9-259.1 kg·hm-2, and has sharply spatial difference. The residualamount in soil. In Northwest China, is more serious than that in North China and Southwest China. Because of difference of tillage and appli-canon ways, there are great differences on the area and shape of the plastic film piece left in soil. The main types of shapes are flaky
Tomaz Fantin de Souza
2013-04-01
Full Text Available In this work, a drawing processed was simulated to calculate forces and the resulting residual stresses in the material. The calculated residual stresses were compared with experimentally measured residual stresses by the Neutron Diffraction Method. The modeled process was the Wire Drawing. The necessary parameters to model the process were taken from an industrial currently used process. Rods of an AISI 1045 steel with nominal diameters of 21.46 mm were reduced to 20.25 mm by drawing with an drawing angle of 15°. Compression tests were used to determinate flow curves of the real material an used in the simulation models. The possibility to estimate drawing forces by numerical simulation was evaluated by comparing simulated results with values from empirical equations given by the literature. The results have shown a sufficient accuracy for the calculation of forces, but the comparison of residual stresses has shown differences to the experimentally determined ones that can be minimized by the consideration of high strain rates in the compression tests, anisotropy of the material and kinematic hardening.
Fu, Yinan; Wand, A Joshua
2013-08-01
High-pressure NMR spectroscopy has emerged as a complementary approach for investigating various structural and thermodynamic properties of macromolecules. Noticeably absent from the array of experimental restraints that have been employed to characterize protein structures at high hydrostatic pressure is the residual dipolar coupling, which requires the partial alignment of the macromolecule of interest. Here we examine five alignment media that are commonly used at ambient pressure for this purpose. We find that the spontaneous alignment of Pf1 phage, d(GpG) and a C12E5/n-hexnanol mixture in a magnetic field is preserved under high hydrostatic pressure. However, DMPC/DHPC bicelles and collagen gel are found to be unsuitable. Evidence is presented to demonstrate that pressure-induced structural changes can be identified using the residual dipolar coupling.
Fu, Yinan; Wand, A. Joshua, E-mail: wand@mail.med.upenn.edu [University of Pennsylvania, Department of Biochemistry and Biophysics, Johnson Research Foundation (United States)
2013-08-15
High-pressure NMR spectroscopy has emerged as a complementary approach for investigating various structural and thermodynamic properties of macromolecules. Noticeably absent from the array of experimental restraints that have been employed to characterize protein structures at high hydrostatic pressure is the residual dipolar coupling, which requires the partial alignment of the macromolecule of interest. Here we examine five alignment media that are commonly used at ambient pressure for this purpose. We find that the spontaneous alignment of Pf1 phage, d(GpG) and a C12E5/n-hexnanol mixture in a magnetic field is preserved under high hydrostatic pressure. However, DMPC/DHPC bicelles and collagen gel are found to be unsuitable. Evidence is presented to demonstrate that pressure-induced structural changes can be identified using the residual dipolar coupling.
Measurement of residual stresses in deposited films of SOFC component materials
Kato, T.; Momma, A.; Nagata, S.; Kasuga, Y. [Electrotechnical Lab., Ibaraki (Japan)
1996-12-31
The stress induced in Solid oxide fuel cells (SOFC)s has important influence on the lifetime of SOFC. But the data on stress in SOFC and mechanical properties of SOW component materials have not been accumulated enough to manufacture SOFC. Especially, the data of La{sub 1-x}Sr{sub x}MnO{sub 3} cathode and La{sub 1-x}Sr{sub x}CrO{sub 3} interconnection have been extremely limited. We have estimated numerically the dependences of residual stress in SOFC on the material properties, the cell structure and the fabrication temperatures of the components, but these unknown factors have caused obstruction to simulate the accurate behavior of residual stress. Therefore, the residual stresses in deposited La{sub 1-x}Sr{sub x}MnO{sub 3} and La{sub 1-x}Sr{sub x}CrO{sub 3} films are researched by the observation of the bending behavior of the substrate strips. The films of SOFC component materials were prepared by the RF sputtering method, because: (1) It can fabricate dense films of poor sinterable material such as La{sub 1-x}Sr{sub x}CrO{sub 3} compared with sintering or plasma spray method. (2) For the complicated material such as perovskite materials, the difference between the composition of a film and that of a target material is generally small. (3) It can fabricate a thick ceramics film by improving of the deposition rate. For example, Al{sub 2}O{sub 3} thick films of 50{mu}m can be fabricated with the deposition rate of approximately 5{mu}m/h industrially. In this paper, the dependence of residual stress on the deposition conditions is defined and mechanical properties of these materials are estimated from the results of the experiments.
Hesam Daryani
2012-09-01
Full Text Available During the past few years, there have been growing interest in learning the relationship between residual income and other financial figures such as dividend per share, market value and operating cash flow. The proposed study of this paper gathers the financial information of all listed firms traded in Tehran Stock Exchange over the period of 2007-2011. We only concentrate on listed companies whose fiscal years started from March to May of each year. The other criterion associated with the proposed study of this paper is that shares of the selected firms must have been active during period of study and there must be no change in their fiscal calendar. The study does not include the shares of holdings, banks, insurance firms. Finally, the information of the firms must be available for course of study. The study uses two regressions analysis and examines five hypotheses including the relationship between residual income and other factors including dividend per share, value added operating cash flow, value added cash flow, market cap and market value added. Using two regression models, all these hypotheses are investigated and the results of the survey confirm a meaningful relationship between residual income and dividend per share, value added operating cash flow, value added cash flow. However, the results of the second model do not confirm the last two hypotheses.
A PFM based digital pixel with off-pixel residue measurement for 15μm pitch MWIR FPAs
Abbasi, Shahbaz; Shafique, Atia; Galioglu, Arman; Ceylan, Omer; Yazici, Melik; Gurbuz, Yasar
2016-05-01
Digital pixels based on pulse frequency modulation (PFM) employ counting techniques to achieve very high charge handling capability compared to their analog counterparts. Moreover, extended counting methods making use of leftover charge (residue) on the integration capacitor help improve the noise performance of these pixels. However, medium wave infrared (MWIR) focal plane arrays (FPAs) having smaller pixel pitch are constrained in terms of pixel area which makes it difficult to add extended counting circuitry to the pixel. Thus, this paper investigates the performance of digital pixels employing off-pixel residue measurement. A circuit prototype of such a pixel has been designed for 15μm pixel pitch and fabricated in 90nm CMOS. The prototype is composed of a pixel front-end based on a PFM loop. The frontend is a modified version of conventional design providing a means for buffering the signal that needs to be converted to a digital value by an off-pixel ADC. The pixel has an integration phase and a residue measurement phase. Measured integration performance of the pixel has been reported in this paper for various detector currents and integration times.
McDonald, E.J.; Exworthy, L.F.; Flewitt, P.E.J. [Magnox Generation, Berkeley (United Kingdom); Hallam, K. [Interface Analysis Centre, Univ. of Bristol (United Kingdom); Bell, W. [Mitsui Babcock Energy Ltd, Renfrew (United Kingdom)
2000-07-01
A trial part through-section excavation manual metal arc repair weld, designed with a view to minimising residual stresses, was prepared by using a critical combination of weld metal strength, bead size and deposition pattern. The repair was in a low alloy ferritic CrMoV steel plate, and the weldment was made using a lower strength C-Mn steel weld metal. Residual stresses have been measured to a high spatial resolution, 1.5 mm, across the weldment using the X-ray diffraction technique with Cr K{alpha} X-radiation. Peak tensile stresses have been identified in the heat affected zone in the parent plate adjacent to the weld metal. Further measurements have been made using the rosette strain gauge centre hole relaxation and deep hole drilling techniques. Results from the experimental techniques are compared and the measured residual stress profiles are discussed with respect to the predictions of a finite element model for this particular multi-pass repair weld. (orig.)
Mishchenko, Andrii; Oliveira, Bruno Jose de; Scotti, Americo, E-mail: asmwelder@gmail.com, E-mail: brunojoliveira7@gmail.com, E-mail: ascotti@mecanica.ufu.br [Universidade Federal de Uberlandia (UFU), MG (Brazil)
2016-10-15
A characteristic feature of the X Ray Diffraction (XRD) method for stress determination is that measurements occur at a thin surface layer. Steel sheets come with surfaces modified by lamination, cleaning (sandblasting, grinding) and even corrosion, which induce residual stresses or roughness inherent to the material. Therefore, surface preparation prior to the residual stress measurement is essential, although no standard procedure seems to be available. A general recommendation is to remove a thin layer so that only residual stresses related to the welding process will be measured. In this study, the use of portable electrolytic equipment was evaluated for mechanized surface material removal. Chemical compositions of electrolytic solutions and the influence of current on the removed material, removal time and temperature during the process were studied. As a result, a suitable chemical solution for electro etching of low carbon steel was developed and a set of “soft” parameters that allowed the removal of about 300 um in a reasonable time was found. Higher currents reduce the removal time, yet increasing the consumption of the solution and plate temperature (which could adversely alter the microstructure or generate thermal stresses). Furthermore, the influence of these parameters on the operability of the process was demonstrated. (author)
Tanaka, K.; Mine, N. (Kyoto University, Kyoto (Japan). Faculty of Engineering); Suzuki, K. (Niigata University, Niigata (Japan). Faculty of Engineering); Kawase, R. (Ariake Institute of Technology, Fukuoka (Japan))
1991-01-15
Alumina ceramics were coated on mild steel by a detonation gun with different amounts of detonation gas, and residual stresses in coated films were measured by X-ray diffraction from the (844) plane of {gamma}-alumina by Cu-K {alpha} radiation. Cracks and pores were observed on the film surface and cross section. The pore increased and the film bulk density decreased with a decrease in amount of detonation gas, and the mechanical Young {prime} s modulus decreased with an increase in pore. Since strains measured mechanically were those in the film bulk with pores while strains measured by X-ray were average values in only crystalline phases, the X-ray Young {prime} s modulus was larger than the mechanical one. The residual stress in films was a large tensile stress and distributed uniformly in films. The residual tensile stress decreased with an increase in amount of detonation gas, however, it was rather insensitive to the film thickness and surface grinding after coating. 10 refs., 8 figs., 2 tabs.
American Society for Testing and Materials. Philadelphia
2010-01-01
1.1 This test method covers the preparation and use of a flat stress-free test specimen for the purpose of checking the systematic error caused by instrument misalignment or sample positioning in X-ray diffraction residual stress measurement, or both. 1.2 This test method is applicable to apparatus intended for X-ray diffraction macroscopic residual stress measurement in polycrystalline samples employing measurement of a diffraction peak position in the high-back reflection region, and in which the θ, 2θ, and ψ rotation axes can be made to coincide (see Fig. 1). 1.3 This test method describes the use of iron powder which has been investigated in round-robin studies for the purpose of verifying the alignment of instrumentation intended for stress measurement in ferritic or martensitic steels. To verify instrument alignment prior to stress measurement in other metallic alloys and ceramics, powder having the same or lower diffraction angle as the material to be measured should be prepared in similar fashion...
农村剩余劳动力测算方法研究%The Methodological Research of Measuring Rural Residual Labor Forces
陈先运
2004-01-01
The paper discussed several current methods to measure rural residual labor forces, forwards a feasible shortcut way to measure, and conducts research and forecast by using the data of Shangdong Province.
INDIRECT METHODS FOR RESIDUAL BIOMASS MEASUREMENT COMING FROM PRUNING OPERATIONS OF URBAN FORESTS
SAJDAK, MAGDALENA
2012-01-01
Una gran cantidad de biomasa residual con posible uso energético e industrial puede ser extraida de las operaciones de gestión de los árboles ornamentales de las ciudades. La rentabilidad del aprovechamiento de estos recursos está condicionada por la cantidad de biomasa existente en los ecosistemas urbanos. Esta investigación se ha centrado en la cuantificac ión directa e indirecta de los residuos biomásicos de la poda de árboles urbanos ornamentales. Las especies estudiadas fueron Morus alga...
Estimation of average causal effect using the restricted mean residual lifetime as effect measure
Mansourvar, Zahra; Martinussen, Torben
2016-01-01
with respect to their survival times. In observational studies where the factor of interest is not randomized, covariate adjustment is needed to take into account imbalances in confounding factors. In this article, we develop an estimator for the average causal treatment difference using the restricted mean...... residual lifetime as target parameter. We account for confounding factors using the Aalen additive hazards model. Large sample property of the proposed estimator is established and simulation studies are conducted in order to assess small sample performance of the resulting estimator. The method is also...
Lu, Guo-Wei; Bo, Tianwai; Sakamoto, Takahide; Yamamoto, Naokatsu; Chan, Calvin Chun-Kit
2016-10-03
Recently the ever-growing demand for dynamic and high-capacity services in optical networks has resulted in new challenges that require improved network agility and flexibility in order for network resources to become more "consumable" and dynamic, or elastic, in response to requests from higher network layers. Flexible and scalable wavelength conversion or multicast is one of the most important technologies needed for developing agility in the physical layer. This paper will investigate how, using a reconfigurable coherent multi-carrier as a pump, the multicast scalability and the flexibility in wavelength allocation of the converted signals can be effectively improved. Moreover, the coherence in the multiple carriers prevents the phase noise transformation from the local pump to the converted signals, which is imperative for the phase-noise-sensitive multi-level single- or multi-carrier modulated signal. To verify the feasibility of the proposed scheme, we experimentally demonstrate the wavelength multicast of coherent optical orthogonal frequency division multiplexing (CO-OFDM) signals using a reconfigurable coherent multi-carrier pump, showing flexibility in wavelength allocation, scalability in multicast, and tolerance against pump phase noise. Less than 0.5 dB and 1.8 dB power penalties at a bit-error rate (BER) of 10-3 are obtained for the converted CO-OFDM-quadrature phase-shift keying (QPSK) and CO-OFDM-16-ary quadrature amplitude modulation (16QAM) signals, respectively, even when using a distributed feedback laser (DFB) as a pump source. In contrast, with a free-running pumping scheme, the phase noise from DFB pumps severely deteriorates the CO-OFDM signals, resulting in a visible error-floor at a BER of 10-2 in the converted CO-OFDM-16QAM signals.
相位噪声对8PSK卫星通信链路的影响%Effect of Phase Noise on Link of Satellite Communication
张金贵; 许星辰
2014-01-01
研究了相位噪声对卫星通信链路传输性能的影响，给出了相位噪声的数字模拟方法，设计了卫星通信链路的基带等效仿真模型，结合8移相键控（8 Phase Shift Keying，8PSK）调制方式及低密度奇偶校验码（Low Density Parity Code，LDPC），仿真了相位噪声频谱特性对卫星通信链路传输性能所造成的恶化。仿真结果表明，当卫星通信链路的相位噪声特性变差时，会影响链路传输性能，甚至会出现误码平台。%With the effect of phase noise on transmission characteristics of the link of satellite communication researched,the numerical simulation means of phase noise is proposed,the base-band equivalent simulation model of satellite communication link is designed,and the effect of phase noise on transmission characteristics of the link of satellite communication is simulated with 8PSK modulation and LDPC error correction.The simulation results show that when the phase noise of the link of satellite communication is worse,the transmission characteristic is affected,and the error-floor is formed even.
Chandrasekar, Ramya
The goal of this thesis was to determine the dependency of swept frequency eddy current (SFEC) measurements on the microstructure of the Ni-based alloy, Inconel 718 as a function of heat treatment and shot peening. This involved extensive characterization of the sample using SEM and TEM coupled with measurements and analysis of the eddy current response of the various sample conditions using SFEC data. Specific objectives included determining the eddy current response at varying depths within the sample, and this was accomplished by taking SFEC measurements in frequencies ranging from 100 kHz to 50 MHz. Conductivity profile fitting of the resulting SFEC signals was obtained by considering influencing factors (such as surface damage). The problems associated with surface roughness and near surface damage produced by shot peening were overcome by using an inversion model. Differences in signal were seen as a result of precipitation produced by heat treatment and by residual stresses induced due to the shot peening. Hardness of the material, which is related both to precipitation and shot peening, was seen to correlate with the measured SFEC signal. Surface stress measurement was carried out using XRD giving stress in the near surface regions, but not included in the calculations due to shallow depth information provided by the technique compared to SFEC. By comparing theoretical SFEC signal computed using the microstructural values (precipitate fraction) and experimental SFEC data, dependency of the SFEC signals on microstructure and residual stress was obtained.
C. Barile
2014-10-01
Full Text Available Residual stresses occur in many manufactured structures and components. Great number of investigations have been carried out to study this phenomenon. Over the years, different techniques have been developed to measure residual stresses; nowadays the combination of Hole Drilling method (HD with Electronic Speckle Pattern Interferometry (ESPI has encountered great interest. The use of a high sensitivity optical technique instead of the strain gage rosette has the advantage to provide full field information without any contact with the sample by consequently reducing the cost and the time required for the measurement. The accuracy of the measurement, however, is influenced by the proper choice of several parameters: geometrical, analysis and experimental. In this paper, in particular, the effects of some of those parameters are investigated: misknowledgment in illumination and detection angles, the influence of the relative angle between the sensitivity vector of the system and the principal stress directions, the extension of the area of analysis and the adopted drilling rotation speed. In conclusion indications are provided to the scope of optimizing the measurement process together with the identification of the major sources of errors that can arise during the measuring and the analysis stages.
Tselniker, Igor; Sigron, Netta; Nazarathy, Moshe
2012-05-07
This paper extends our prior coherent MSDD Carrier Recovery system from QPSK to QAM operation and also characterizes for the first time the Carrier Frequency Offset (CFO) mitigation capabilities of the novel MSDD for QAM systems. We introduce and numerically investigate the performance of an improved MSDD carrier recovery system (differing from the one disclosed in our MSDD for QPSK prior paper), automatically adapting to the channel statistics for optimal phase-noise mitigation. Remarkably, we do not require a separate structure to estimate and mitigate CFO, but the same adaptive structure originally intended for phase noise mitigation is shown to also automatically provide frequency offset estimation and recovery functionality. The CFO capture range of our system is in principle infinite, whereas prior CFO mitigation systems have CFO capture ranges limited to a small a fraction of the baud-rate. When used for 16-QAM with coherent-grade lasers of 100 KHz linewidth, our MSDD system attains the best tradeoffs between performance and complexity, relative to other carrier recovery systems combining blind-phase-search with maximum likelihood detection. We also present additional MSDD phase-noise recovery system variants whereby substantially reduced complexity is traded off for slightly degraded performance. Our MSDD system is able to switch "on-the-fly" to various m-QAM constellation sizes, e.g. seamlessly transition between 16-QAM and QPSK, which may be useful for dynamically adaptive optical networks.
相位噪声对OFDM/OQAM系统的影响%Effect of phase noise in an OFDM/OQAM system
陈琦帆; 吴炳洋; 程时昕
2003-01-01
The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation of OFDM/OQAM is first derived with the square root raised cosine (SRRC) filter as the pulse-shaping filter. Then the effect of multiplicative phase noise is equivalently represented as additive white Gaussian noise (AWGN), the variance of which is given analytically. We can observe that the same result as OFDM/QAM system is derived. Lastly, all the analytical results are verified by the bit error rate (BER) degradation through Monte Carlo simulation.%分析了相位噪声对OFDM/OQAM系统性能的影响,分析的结果可用于指导设计低成本的调谐器.分析过程如下:首先导出了离散时间的采用SRRC成型滤波器的OFDM/OQAM系统公式;然后将乘性相位噪声等效表示为加性白高斯噪声,并给出了解析的方差表达式,该表达式与OFDM/QAM系统类似;最后利用BER的下降作为性能指标,采用蒙特卡罗仿真验证了我们的分析结果.
A Comparison of Residual Stress Measuring Techniques: Their Strengths and Weaknesses
1980-08-01
1 i OJ 1 ll CM 1 t~- VD CO OJ V* -J iv 1 a. viJ b * r-l .J" _J -^r -a- r^ a; ON 00 cn m OJ «.>. u o rH CM CO a.i (H 3 irv OT ^f pi r i...components of stress are given by the Kirsch (ref 7) equations, namely: CTrr = a (1 - a 2) + a (1 + 3a.k - 4a2) cos 20 (4) rr 2 T2" 2...G. E. Bowie, "Residual Stress by Blind-Hole Method with 0££-Center Hole," Exp. Mech., lg. No. 5, (May 1978), pp 173-179. 7. G. Kirsch , "Die Theorie
Neutron-diffraction measurement of residual stresses in Al-Cu cold-cut welding
Fiori, F
2002-01-01
Usually, when it is necessary to join different materials with a large difference in their melting points, welding should be avoided. To overcome this problem we designed and built a device to obtain cold-cut welding, which is able to strongly decrease oxidation problems of the surfaces to be welded. Thanks to this device it is possible to achieve good joining between different pairs of materials (Al-Ti, Cu-Al, Cu-Al alloys) without reaching the material melting point. The mechanical and microstructural characterisation of the joining and the validation of its quality were obtained using several experimental methods. In particular, in this work neutron-diffraction experiments for the evaluation of residual stresses in Cu-Al junctions are described, carried out at the G5.2 diffractometer of LLB, Saclay. Neutron-diffraction results are presented and related to other experimental tests such as microstructural characterisation (through optical and scanning electron microscopy) and mechanical characterisation (ten...
SHEN Xiaoyan; LIN Yuchi; WANG Wei
2009-01-01
Fatigue behaviour has important implications for engineering composite structures in sectors ranging from automotive to aerospace. Optical sensing technology displays excellent performance in these fields for monitoring. In this paper, temperature and residual strain during fatigue of a carbon fiber reinforced polymer(CFRP) are investigated. Four autoclaved CFRP beam specimens, with fiber Bragg grating(FBG) sensors and thermocouples embedded at selected locations, are subjected to three-point bending cyclic loading on the BOSE testing machine for fatigue testing. Thermocouples are used to measure the temperature while FBGs can sense the temperature and strain as well. Seven tests in total are conducted at different frequencies, and each test lasts for several days. From the experimental results, transient steep peaks of temperature increases (up to 2.3 ℃) are discovered at the beginning of the load. The following constant temperature increments are around 1.0 ℃, which is not relevant to frequencies from 0.1 Hz to 20 Hz and suspected due to fatigue. Residual strains of 1×10-5-2×10-5 during fatigue, fading away rapidly when unloading, are also reported. Embedded FBGs here are validated to sense temperature and strains in composite structures, which demonstrates promising potentials in structure monitoring fields. CFRP are verified to have an excellent performance during fatigue with low temperature increase and residual strain.
Residual strain measurements of a fatigued metal stick and heat treated steel pipe at JRR3M-RESA
Inoue, Kazuko; Horikawa, Takeshi; Kawashima, Hisaichi [Ryukoku Univ., Kyoto (Japan); Minakawa, Nobuaki; Tsuchiya, Yoshinori
1997-06-01
A residual strain on section of notched edge after fatiguing the carbon steel round bar with ring shape and semi-circular section and on thick direction of 13% Cr-steel pipe for oil well heat-treated after machining was tried to test. It was one of the initial experiments in residual strain measurement apparatus (RESA; old name is DIVE) installed at T2-1 port of JRR-3M to test a residual strain at section of 8 mm in diameter of the fatigue specimen at three (x{sup -}, y{sup -} and z{sup -}) directions on a fine mesh of 1 mm step. This test has another aim to inspect the apparatus itself such as obtained accuracy, required testing time, and so on, except original aim to find out strain of the specimen. As a result of the initial experiment, a lot of points to be investigated and improved were found out. According to these results, at present a fatigue specimen with large diameter (40 mm) is now in preparation. And, as is now processing on improvement of a monochromator to increase the beam intensity and so on, a higher resolution as well as a finer (about 1 micron) beam diameter for the specimen is expected to establish. (G.K.)
Residual stress measurement with high energy x-rays at the Advanced Photon Source.
Winholtz, R. A.; Haeffner, D. R.; Green, R.E.L.; Varma, R.; Hammond, D.
2000-03-02
Preliminary measurements with high energy x-rays from the SRI CAT 1-ID beam line at the Advanced Photon show great promise for the measurement of stress and strain using diffraction. Comparisons are made with neutron measurements. Measurements of strains in a 2 mm thick 304 stainless steel weld show that excellent strain and spatial resolutions are possible. With 200 {micro}m slits, strain resolutions of 1 x 10{sup {minus}5} were achieved.
2015-05-20
classes of statistics. The latter situation is the standard setting of risk-averse stochastic programming; see for example [13, 26]. Due to incomplete ...measures of risk and related quantifiers, and a theorem about connections among such quantifiers under relaxed assumptions. Section 3 defines measures of... Theorem in [26] to the broader class of regular measures defined here and also include additional characterizations of deviation measures and statistics
Osten, W.; Pedrini, G.; Weidmann, P.; Gadow, R.
2015-08-01
A minimum invasive but high resolution method for residual stress analysis of ceramic coatings made by thermal spraycoating using a pulsed laser for flexible hole drilling is described. The residual stresses are retrieved by applying the measured surface data for a model-based reconstruction procedure. While the 3D deformations and the profile of the machined area are measured with digital holography, the residual stresses are calculated by FE analysis. To improve the sensitivity of the method, a SLM is applied to control the distribution and the shape of the holes. The paper presents the complete measurement and reconstruction procedure and discusses the advantages and challenges of the new technology.
Albertini, G.; Bruno, G.; Fiori, F.; Girardin, E.; Giuliani, A.; Quadrini, E.; Romani, F.
2000-03-01
Thermal austenitizing and tempering treatments are being developed in automotive industry to prevent crack initiation and propagation, especially in components where stress intensity factors influence the stress field and ultimately the fatigue life of the component. This is the case of crown gears, where the tooth root typically undergoes impulsive and very high loads which frequently cause cracking if tensile residual stresses are present at the surface. The sign reversal of these stresses is the aim of austenitizing and tempering treatments. In this work neutron diffraction measurements of residual stress (RS) on a UNI55Cr3 steel crown gear, carried out at HMI-BENSC , are presented. The sample was submitted to a new multi-frequency induction technique whose effectiveness was checked. Comparisons with X-ray measurements are shown, and RS measured by X-rays on a similar shot-peened sample are also mentioned. Experiments at HMI-BENSC have received financial support by the European Commission under the TMR/LSF Access Programme (contract no. ERBFMGE CT950060).
Valente, T.; Bartuli, C.; Sebastiani, M.; Loreto, A.
2005-12-01
The experimental measurement of residual stresses originating within thick coatings deposited by thermal spray on solid substrates plays a role of fundamental relevance in the preliminary stages of coating design and process parameters optimization. The hole-drilling method is a versatile and widely used technique for the experimental determination of residual stress in the most superficial layers of a solid body. The consolidated procedure, however, can only be implemented for metallic bulk materials or for homogeneous, linear elastic, and isotropic materials. The main objective of the present investigation was to adapt the experimental method to the measurement of stress fields built up in ceramic coatings/metallic bonding layers structures manufactured by plasma spray deposition. A finite element calculation procedure was implemented to identify the calibration coefficients necessary to take into account the elastic modulus discontinuities that characterize the layered structure through its thickness. Experimental adjustments were then proposed to overcome problems related to the low thermal conductivity of the coatings. The number of calculation steps and experimental drilling steps were finally optimized.
Residual stress measurements with barkhausen noise in power plant creep failure analysis
Karvonen, I. [CoMoTest Oy, Maentsaelae (Finland)] Suominen, L. [Stresstech Oy, Jyvaeskylae (Finland)
1997-12-31
Continuously developing power and process industry needs predictive maintenance inspection methods in order to prevent failures with correctly timed and properly specified measures. Materials` monitoring has traditionally been non-destructive inspection to detect growing cracks or other deficiencies. Recently, after the development of portable stress measurement systems, some advances has been reached. Based on stress anomalies due to creep, fatigue or corrosion, new applications have been found in the use of Barkhausen noise inspection. When the Barkhausen noise findings have been simultaneously confirmed with other stress measuring methods, a wider acceptance of the application of the method can be proposed. (orig.) 7 refs.
Zhu, Qimeng; Chen, Jia; Gou, Guoqing; Chen, Hui; Li, Peng; Gao, W.
2016-10-01
Residual stress measurement and control are highly important for the safety of structures of high-speed trains, which is critical for the structure design. The longitudinal critically refracted wave technology is the most widely used method in measuring residual stress with ultrasonic method, but its accuracy is strongly related to the test parameters, namely the flight time at the free-stress condition ( t 0), stress coefficient ( K), and initial stress (σ0) of the measured materials. The difference of microstructure in the weld zone, heat affected zone, and base metal (BM) results in the divergence of experimental parameters. However, the majority of researchers use the BM parameters to determine the residual stress in other zones and ignore the initial stress (σ0) in calibration samples. Therefore, the measured residual stress in different zones is often high in errors and may result in the miscalculation of the safe design of important structures. A serious problem in the ultrasonic estimation of residual stresses requires separation between the microstructure and the acoustoelastic effects. In this paper, the effects of initial stress and microstructure on stress coefficient K and flight time t 0 at free-stress conditions have been studied. The residual stress with or without different corrections was investigated. The results indicated that the residual stresses obtained with correction are more accurate for structure design.
Xiong, Fuqin; Andro, Monty
2001-01-01
This paper first shows that the Doppler frequency shift affects the frequencies of the RF carrier, subcarriers, envelope, and symbol timing by the same percentage in an Orthogonal Frequency Division Multiplexing (OFDM) signal or any other modulated signals. Then the SNR degradation of an OFDM system due to Doppler frequency shift, frequency offset of the local oscillators and phase noise is analyzed. Expressions are given and values for 4-, 16-, 64-, and 256-QAM OFDM systems are calculated and plotted. The calculations show that the Doppler shift of the D3 project is about 305 kHz, and the degradation due to it is about 0.01 to 0.04 dB, which is negligible. The degradation due to frequency offset and phase noise of local oscillators will be the main source of degradation. To keep the SNR degradation under 0.1 dB, the relative frequency offset due to local oscillators must be below 0.01 for the 16 QAM-OFDM. This translates to an offset of 1.55 MHz (0.01 x 155 MHz) or a stability of 77.5 ppm (0.01 x 155 MHz/20 GHz) for the DI project. To keep the SNR degradation under 0.1 dB, the relative linewidth (0) due to phase noise of the local oscillators must be below 0.0004 for the 16 QAM-OFDM. This translates to a linewidth of 0.062 MHz (0.0004 x 155 MHz) of the 20 GHz RIF carrier. For a degradation of 1 dB, beta = 0.04, and the linewidth can be relaxed to 6.2 MHz.
X-ray residual stress measurements on cold-drawn steel wire
Willemse, P.F.; Naughton, B.P.; Verbraak, C.A.
1982-01-01
The interplanar spacing d{hkl} versus sin2 ψ distributions were measured for the 211, 310, 220 and 200 reflections from severely cold-drawn 0.7% C steel wire with a diameter of 0.25 mm. From the shape of the curves it was concluded that, as well as a 110 fibre texture and elastic anisotropy, plastic
X-ray residual stress measurements on cold-drawn steel wire
Willemse, P.F.; Naughton, B.P.; Verbraak, C.A.
1982-01-01
The interplanar spacing d{hkl} versus sin2 ψ distributions were measured for the 211, 310, 220 and 200 reflections from severely cold-drawn 0.7% C steel wire with a diameter of 0.25 mm. From the shape of the curves it was concluded that, as well as a 110 fibre texture and elastic anisotropy, plastic
Castellini, P.; Stroppa, L.; Paone, N.
2012-05-01
The paper presents the laser sheet scattered light technique, a fast optical non contact method for measuring internal stress distribution over a cross section of flat glass specimens, designed for closed loop control of glass tempering furnaces. The technique is an evolution of the scattered light method for flat glass residual stress analysis and allows a full thickness stress profile to be measured with a single shot acquisition across a glass plate without any contact. A linearly polarized laser sheet, shaped into a thin plane of parallel light beams, enters orthogonally to the side of the flat glass illuminating its full thickness. Light sheet is orthogonal to the glass surface and travels parallel to it. Stress induced birefringence through the glass affects light polarization, thus scattered light intensity detected at 90° with respect to the polarization of the incident light appears spatially modulated in intensity. A camera aligned orthogonal to the laser light polarization collects an image of fringes whose shape is digitally analyzed to measure the thickness stress state. The paper describes the development of this technique by recalling the scattered light method, then describing its automation by scanning a collimated beam across the glass thickness and finally by showing that the scan method can be substituted by the light sheet method. Light sheet method provides a full field non contact stress measurement across the glass thickness, thus allowing for a fast inspection method, suitable for industrial use. Flat glass items for industrial use have bevelled edges; this does not allow measurements close to glass surface. To solve this limit, experimental data are extrapolated by a symmetrical polynomial fitting and imposing a zero integral to the stress profile. Results on surface stress measured by the laser sheet scattered method are in agreement with those of the automated light scattered method and show a fair agreement with measurement by an
Kervella, Gaël; Van Dijk, Frederic; Pillet, Grégoire; Lamponi, Marco; Chtioui, Mourad; Morvan, Loïc; Alouini, Mehdi
2015-08-01
We report on the stabilization of a 90-GHz millimeter-wave signal generated from a fully integrated photonic circuit. The chip consists of two DFB single-mode lasers whose optical signals are combined on a fast photodiode to generate a largely tunable heterodyne beat note. We generate an optical comb from each laser with a microwave synthesizer, and by self-injecting the resulting signal, we mutually correlate the phase noise of each DFB and stabilize the beatnote on a multiple of the frequency delivered by the synthesizer. The performances achieved beat note linewidth below 30 Hz.
Hödemann, S.; Möls, P.; Kiisk, V.; Murata, T.; Saar, R.; Kikas, J.
2015-12-01
A new optical method is presented for evaluation of the stress profile in chemically tempered (chemically strengthened) glass based on confocal detection of scattered laser beam. Theoretically, a lateral resolution of 0.2 μm and a depth resolution of 0.6 μm could be achieved by using a confocal microscope with high-NA immersion objective. The stress profile in the 250 μm thick surface layer of chemically tempered lithium aluminosilicate glass was measured with a high spatial resolution to illustrate the capability of the method. The confocal method is validated using transmission photoelastic and Na+ ion concentration profile measurement. Compositional influence on the stress-optic coefficient is calculated and discussed. Our method opens up new possibilities for three-dimensional scattered light tomography of mechanical imaging in birefringent materials.
Hödemann, S., E-mail: siim.hodemann@ut.ee; Möls, P.; Kiisk, V.; Saar, R.; Kikas, J. [Institute of Physics, University of Tartu, Wilhelm Ostwald st., Tartu 50411 (Estonia); Murata, T. [Nippon Electric Glass Co., 7-1 Seiran 2-chome, Otsu-shi, Shiga 520-8639 (Japan)
2015-12-28
A new optical method is presented for evaluation of the stress profile in chemically tempered (chemically strengthened) glass based on confocal detection of scattered laser beam. Theoretically, a lateral resolution of 0.2 μm and a depth resolution of 0.6 μm could be achieved by using a confocal microscope with high-NA immersion objective. The stress profile in the 250 μm thick surface layer of chemically tempered lithium aluminosilicate glass was measured with a high spatial resolution to illustrate the capability of the method. The confocal method is validated using transmission photoelastic and Na{sup +} ion concentration profile measurement. Compositional influence on the stress-optic coefficient is calculated and discussed. Our method opens up new possibilities for three-dimensional scattered light tomography of mechanical imaging in birefringent materials.
Jeon, Sang Won; Han, Changsu; Ko, Young-Hoon; Yoon, Seo Young; Pae, Chi-Un; Choi, Joonho; Park, Yong Chon; Kim, Jong-Woo; Yoon, Ho-Kyoung; Ko, Seung-Duk; Patkar, Ashwin A.; Zimmerman, Mark
2017-01-01
Objective This study was aimed at evaluating the diagnostic validity of the Korean version of the Clinically Useful Depression Outcome Scale (CUDOS) with varying follow-up in a typical clinical setting in multiple centers. Methods In total, 891 psychiatric outpatients were enrolled at the time of their intake appointment. Current diagnostic characteristics were examined using the Structured Clinical Interview for DSM-IV (41% major depressive disorder). The CUDOS was measured and compared with three clinician rating scales and four self-report scales. Results The CUDOS showed excellent results for internal consistency (Cronbach’s α, 0.91), test-retest reliability (patients at intake, r=0.81; depressed patients in ongoing treatment, r=0.89), and convergent and discriminant validity (measures of depression, r=0.80; measures of anxiety and somatization, r=0.42). The CUDOS had a high ability to discriminate between different levels of depression severity based on the rating of Clinical Global Impression for depression severity and the diagnostic classification of major depression, minor depression, and non-depression. The ability of the CUDOS to identify patients with major depression was high (area under the receiver operating characteristic curve=0.867). A score of 20 as the optimal cutoff point was suggested when screening for major depression using the CUDOS (sensitivity=89.9%, specificity=69.5%). The CUDOS was sensitive to change after antidepressant treatment: patients with greater improvement showed a greater decrease in CUDOS scores (pKorean version of the CUDOS is a very useful measurement for research and for clinical practice. PMID:28138107
Breno Carvalho
2013-10-01
Full Text Available This paper purpose is to implement a computational program to estimate the states (complex nodal voltages of a power system and showing that the largest normalized residual (LNR test fails many times. The chosen solution method was the Weighted Least Squares (WLS. Once the states are estimated a gross error analysis is made with the purpose to detect and identify the measurements that may contain gross errors (GEs, which can interfere in the estimated states, leading the process to an erroneous state estimation. If a measure is identified as having error, it is discarded of the measurement set and the whole process is remade until all measures are within an acceptable error threshold. To validate the implemented software there have been done several computer simulations in the IEEE´s systems of 6 and 14 buses, where satisfactory results were obtained. Another purpose is to show that even a widespread method as the LNR test is subjected to serious conceptual flaws, probably due to a lack of mathematical foundation attendance in the methodology. The paper highlights the need for continuous improvement of the employed techniques and a critical view, on the part of the researchers, to see those types of failures.
Lee, Jung Ho; Li, Fang; Grishaev, Alexander; Bax, Ad
2015-02-04
Three-bond (3)J(C'C') and (3)J(HNHα) couplings in peptides and proteins are functions of the intervening backbone torsion angle ϕ. In well-ordered regions, (3)J(HNHα) is tightly correlated with (3)J(C'C'), but the presence of large ϕ angle fluctuations differentially affects the two types of couplings. Assuming the ϕ angles follow a Gaussian distribution, the width of this distribution can be extracted from (3)J(C'C') and (3)J(HNHα), as demonstrated for the folded proteins ubiquitin and GB3. In intrinsically disordered proteins, slow transverse relaxation permits measurement of (3)J(C'C') and (3)J(HNH) couplings at very high precision, and impact of factors other than the intervening torsion angle on (3)J will be minimal, making these couplings exceptionally valuable structural reporters. Analysis of α-synuclein yields rather homogeneous widths of 69 ± 6° for the ϕ angle distributions and (3)J(C'C') values that agree well with those of a recent maximum entropy analysis of chemical shifts, J couplings, and (1)H-(1)H NOEs. Data are consistent with a modest (≤30%) population of the polyproline II region.
Phase Noise Estimation in CO-OFDM System of Transmission System%CO-OFDM传输系统相位噪声估计
王利君
2011-01-01
In this paper, the effect of laser phase offsets in CO-OFDM is theoretically analysed, and it is pionted out that the phase noise is main noise source in CO-OFDM. Based on the conventional radio OFDM channel estimation, a pilot-aided method of phase noise estimation and compensation are proposed. By using simulation in OptiSystem, this method can impove transmission performance of CO-OFDM system.%从理论上分析了激光器相位偏移对相干光正交频分复用(CO-OFDM)系统传输性能影响,并指出相位噪声是相干光OFDM主要噪声源.在传统无线OFDM信道估计基础上,提出了一种基于导频子载波的相位噪声估计和补偿方法,在OptiSystem中建立CO-OFDM系统仿真模型,通过仿真证明了该方法可以有效地改善CO-OFDM系统传输性能.
Sander, Pia; Mouritsen, L; Andersen, J Thorup
2002-01-01
OBJECTIVE: The aim of this study was to evaluate the value of routine measurements of urinary flow rate and residual urine volume as a part of a "minimal care" assessment programme for women with urinary incontinence in detecting clinical significant bladder emptying problems. MATERIAL AND METHOD...... female urinary incontinence. Thus, primary health care providers can assess women based on simple guidelines without expensive equipment for assessment of urine flow rate and residual urine....
Saro S.
2011-10-01
Full Text Available Fragment mass distributions for ﬁssion after full momentum transfer were measured in the reactions of 30Si,34,36 S,31P,40Ar + 238U at bombarding energies around the Coulomb barrier. Mass distributions change signiﬁcantly as a function of incident beam energy. The asymmetric ﬁssion probability increases at sub-barrier energy. The phenomenon is interpreted as an enhanced quasiﬁssion probability owing to orientation effects on fusion and/or quasiﬁssion. The evaporation residue (ER cross sections were measured in the reactions of 30Si + 238U and 34S + 238U to obtain information on fusion. In the latter reaction, signiﬁcant suppression of fusion was implied. This suggests that ﬁssion events different from compound nucleus are included in the masssymmetric fragments. The results are supported by a model calculation based on a dynamical calculation using Langevin equation, in which the mass distribution for fusion-ﬁssion and quasiﬁssion fragments are separately determined.
WANG Qiang; WANG Biao; MA De-cai; DAI Fu-long
2006-01-01
Residual stresses in ion-implanted NiTi alloy are measured by a combined method of Moiré interferometry and hole-drilling. Oxygen ions are implanted into the NiTi alloy under a voltage of 30 kV by a dose of 1.0×1017 ions/cm2 for one hour. Subsequently, in order to avoid dimensional error, a hole is drilled exactly in the center of the sample. The distribution of residual stresses around the hole is measured. It is indicated that the method which combines the Moiré interferometry with hole-drilling is able to be used to measure residual stresses produced by ion implantation.
Van Stappen, Johan; Pigozzi, Chiara; Tepaske, Robert; Van Regenmortel, Niels; De Laet, Inneke; Schoonheydt, Karen; Dits, Hilde; Severgnini, Paolo; Roberts, Derek J; Malbrain, Manu L N G
2014-01-01
Gastric residual volume (GRV) can be measured in a variety of ways in critically ill patients, most often, the nasogastric tube is disconnected and the GRV is aspirated via a 60 mL syringe. Bladder pressure (IBP) measurement is the gold standard for intra-abdominal pressure (IAP) estimation. This study will look at the validation of a novel method combining measurement of GRV and estimation of IAP via intra-gastric pressure (IGP). In total 135 paired IAP and 146 paired GRV measurements were performed in 37 mechanically ventilated ICU patients. The IAP was estimated via the bladder (i.e. IBP) using the FoleyManometer and via the stomach (i.e. IGP) with the new device. The GRV was measured with the new device (GRVprototype) and via the classic method (GRVclassic). The devices were provided by Holtech Medical (Charlottenlund, Denmark) and data were retrospectively analysed. The number of paired measurements in each patient was 4 ± 1. The mean IBP was 10.7 ± 4.1 and mean IGP was 11.6 ± 4.1 mm Hg. Correlation between the IBP and IGP was significant, however moderate (R2 = 0.51). Analysis according to Bland and Altman showed a bias and precision of 0.8 and 2.7 mm Hg respectively, however the limits of agreement (LA) were large and ranged from -4.5 to 6.1 mm Hg. Changes in IGP correlated well with changes in IBP. The median GRVprototype was 80 mL (0-1050) and equal to the median GRVclassic of 80 mL (0-1250). Correlation between the 2 methods was excellent (R2 = 0.89). Analysis according to Bland and Altman showed a bias and precision of -0.8 and 52.3 mL respectively and the LA ranged from -103 to 102 mL. Changes in GRVclassic correlated well with changes in GRVprototype. The results of this multicentre pilot study show that GRV can be measured with the new device. Furthermore this allows simultaneous screening for intra-abdominal hypertension with IAP estimation via IGP.
X-ray measurement of residual stresses in laser surface melted Ti-6Al-4V alloy
Robinson, J.M.; van Brussel, B.A.; de Hosson, J.T.M.; Reed, R.C.
1996-01-01
In this paper, we report on the residual stresses in laser surface melted Ti-6Al-4V, determined using X-ray diffraction methods. The principal result is that there is an increase in the transverse residual stress with each successive, overlapping laser track. The result can be used to explain the ob
de Almeida, Valmor F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liu, Hongjun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Herwig, Kenneth W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kidder, Michelle [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2016-01-25
That incoherent scattering from protiated molecular liquids adds a constant background to the measured scattering intensity is well known, but less appreciated is the fact that coherent scattering is also induced by the presence of hydrogen in a deuterated liquid. In fact, the scattering intensity can be very sensitive, in the small-q region, with respect to the amounts and distribution of residual H in the system. We used 1,4-dioxane liquid to demonstrate that the partial structure factors of the HD and DD atom pairs contribute significantly to inter-molecular scattering and that uncertainty in the extent of deuteration account for discrepancies between simulations and measurements. Both contributions to uncertainty have similar magnitudes: scattering interference of the hydrogen-deuterium pair, and complementary interference from the deuterium-deuterium pair by virtue of chemical inhomogeneity. This situation arises in practice since deuteration of liquids is often 99% or less. A combined experimental and extensive computational study of static thermal neutron scattering of 1,4-dioxane demonstrates the foregoing. We show, through simulations, that the reason for the differences is the content of protiated dioxane (vendors quote 1%). We estimate that up to 5% (at 298K and at 343K) protiated mole fraction may be involved in generating the scattering differences. Finally, we find that the particular distribution of hydrogen in the protiated molecules affects the results significantly; here we considered molecules to be either fully protiated or fully deuterated. This scenario best reconciles the computational and experimental results, and leads us to speculate that the deuteration synthesis process tends to leave a molecule either fully deuterated or fully protiated. Although we have used 1,4-dioxane as a model liquid, the effects described in this study extend to similar liquids and similar systematic experimental/computational studies can be performed to either
2014-03-01
significant amount of grinding and other sorts of damage marks that may have influenced the measurements. These measurements will be repeated on non...Mech. Eng., Naval Postgraduate School, Monterey, CA, 2012. 107 [24] M. Pourbaix, Atlas of Electrochemical Equilibria, Houston, TX: National...Journal of Electrochemical Science and Technology, vol. 129, no. 12, pp. 2660–2665, Dec. 1982. [26] H. L. Logan, "Film rupture mechanism of stress
Wideband CMOS LC VCO design and phase noise analysis%宽带CMOS LC压控振荡器设计及相位噪声分析
郭雪锋; 王志功; 李智群; 唐路
2008-01-01
A wideband LC cross-coupled voltage controlled oscillator(VCO) is designed and realized with standard 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology. Band switching capacitors are adopted to extend the frequency tuning range, and the phase noise is optimized in the design procedure. The functional relationships between the phase noise and the transistors' width-length ratios are deduced by a linear time variant (LTV) model. The theoretical optimized parameter value ranges are determined. To simplify the calculation, the working region is split into several sub-ranges according to transistor working conditions. Thus, a lot of integrations are avoided, and the phase noise function upon the design variables can be expressed as simple proportion formats. Test results show that the DC current is 8. 8 mA under a voltage supply of 1.8 V; the frequency range is 1.17 to 1.90 GHz, and the phase noise reaches -83 dBc/Hz at a 10 kHz offset from the carrier. The chip size is 1.2 mm × 0. 9 mm.%应用标准0.18 μm CMOS工艺设计并实现了宽带交叉耦合LC压控振荡器.采用开关电容阵列拓宽频率范围.设计过程中对相位噪声进行了优化.应用线性时变模型(LTV)推导出相位噪声与MOS晶体管宽长比之间的函数关系,从理论上给出相位噪声性能最优的元件参数取值范围.为简化推导过程,针对电路特点按晶体管工作状态来细分电路工作区域,从而避免了大量积分运算,以尽可能简单的比例形式得到相位噪声与设计变量间的函数关系.测试结果表明,在1.8 V电源电压下,核心电路工作电流为8.8 mA,压控振荡器的频率范围为1.17～1.90 GHz,10 kHz频偏处相位噪声达到-83 dBc/Hz.芯片面积为1.2 mm×0.9 mm.
Øyvind Skreiberg
2012-02-01
Full Text Available An experimental investigation was carried out to study the NOx formation and reduction by primary measures for five types of biomass (straw, peat, sewage sludge, forest residues/Grot, and wood pellets and their mixtures. To minimize the NOx level in biomass-fired boilers, combustion experiments were performed in a laboratory scale multifuel fixed grate reactor using staged air combustion. Flue gas was extracted to measure final levels of CO, CO2, CxHy, O2, NO, NO2, N2O, and other species. The fuel gas compositions between the first and second stage were also monitored. The experiments showed good combustion quality with very low concentrations of unburnt species in the flue gas. Under optimum conditions, a NOx reduction of 50–80% was achieved, where the highest reduction represents the case with the highest fuel-N content. The NOx emission levels were very sensitive to the primary excess air ratio and an optimum value for primary excess air ratio was seen at about 0.9. Conversion of fuel nitrogen to NOx showed great dependency on the initial fuel-N content, where the blend with the highest nitrogen content had lowest conversion rate. Between 1–25% of the fuel-N content is converted to NOx depending on the fuel blend and excess air ratio. Sewage sludge is suggested as a favorable fuel to be blended with straw. It resulted in a higher NOx reduction and low fuel-N conversion to NOx. Tops and branches did not show desirable NOx reduction and made the combustion also more unstable. N2O emissions were very low, typically below 5 ppm at 11% O2 in the dry flue gas, except for mixtures with high nitrogen content, where values up to 20 ppm were observed. The presented results are part of a larger study on problematic fuels, also considering ash content and corrosive compounds which have been discussed elsewhere.
Zhang, Sheng; Li, Chiang-Shan Ray
2010-01-15
Brain imaging has provided a useful tool to examine the neural processes underlying human cognition. A critical question is whether and how task engagement influences the observed regional brain activations. Here we highlighted this issue and derived a neural measure of task engagement from the task-residual low-frequency blood oxygenation level-dependent (BOLD) activity in the precuneus. Using independent component analysis, we identified brain regions in the default circuit - including the precuneus and medial prefrontal cortex (mPFC) - showing greater activation during resting as compared to task residuals in 33 individuals. Time series correlations with the posterior cingulate cortex as the seed region showed that connectivity with the precuneus was significantly stronger during resting as compared to task residuals. We hypothesized that if the task-residual BOLD activity in the precuneus reflects engagement, it should account for a certain amount of variance in task-related regional brain activation. In an additional experiment of 59 individuals performing a stop signal task, we observed that the fractional amplitude of low-frequency fluctuation (fALFF) of the precuneus but not the mPFC accounted for approximately 10% of the variance in prefrontal activation related to attentional monitoring and response inhibition. Taken together, these results suggest that task-residual fALFF in the precuneus may be a potential indicator of task engagement. This measurement may serve as a useful covariate in identifying motivation-independent neural processes that underlie the pathogenesis of a psychiatric or neurological condition.
Peixoto Filho, Flavio Tito; Goncalves Junior, Armando Albertazzi [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Lab. de Metrologia e Automatizacao (LABMETRO)
2004-07-01
There is always a constant concern about the pipelines' integrity. An important control parameter is the level of total mechanical stresses acting over the pipeline. However, the loading and residual stresses acting on a pipeline are not measured in the field as much as necessary. Technical difficulties and the high cost of the nowadays techniques and the hostile measurement conditions are the main reason for that. An alternative method has been developed at the Universidade Federal de Santa Catarina (UFSC) since 1992. A new optical measurement device is used to measure strains, mechanical stresses and residual stresses acting over the structure. A metrological and functional evaluation of this system is the main focus of this paper. (author)
Kopeikin, S M
1998-01-01
Pulsars are the most stable natural frequency standards. They can be applied to a number of principal problems of modern astronomy and time-keeping metrology. The full exploration of pulsar properties requires obtaining unbiased estimates of the spin and orbital parameters. These estimates depend essentially on the random noise component being revealed in the residuals of time of arrivals (TOA). In the present paper, the influence of low-frequency ("red") timing noise with spectral indices from 1 to 6 on TOA residuals, variances, and covariances of estimates of measured parameters of single and binary pulsars are studied. In order to determine their functional dependence on time, an analytic technique of processing of observational data in time domain is developed which takes into account both stationary and non-stationary components of noise. Our analysis includes a simplified timing model of a binary pulsar in a circular orbit and procedure of estimation of pulsar parameters and residuals under the influenc...
Harri LILLE
2016-05-01
Full Text Available Hard gold and silver are applied in coating owing to their high hardness, good wear and corrosion resistance for engineering application (e.g. on generators slip rings, sliding contacts and small machine parts and are typically plated on copper (mostly, brass and bronze. The studied nickel-hardened gold and silver coatings were brush plated on open thin-walled copper ring substrates. Residual stresses in the coatings were calculated from the curvature changes of the substrates. Biaxial intrinsic residual stresses were also determined by nanoindentation testing and by the X-ray technique. The values of the residual stresses represented tensile stresses and when determined by the techniques used they were comparable within a maximum limit of measurement uncertainty. These stresses relax; the dependence of relaxation time was approximated by a linear-fractional function.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7439
Nakagawa, Hiroshi; Tajima, Takahiro; Kano, Manabu; Kim, Sanghong; Hasebe, Shinji; Suzuki, Tatsuya; Nakagami, Hiroaki
2012-04-17
The usefulness of infrared-reflection absorption spectroscopy (IR-RAS) for the rapid measurement of residual drug substances without sampling was evaluated. In order to realize the highly accurate rapid measurement, locally weighted partial least-squares (LW-PLS) with a new weighting technique was developed. LW-PLS is an adaptive method that builds a calibration model on demand by using a database whenever prediction is required. By adding more weight to samples closer to a query, LW-PLS can achieve higher prediction accuracy than PLS. In this study, a new weighting technique is proposed to further improve the prediction accuracy of LW-PLS. The root-mean-square error of prediction (RMSEP) of the IR-RAS spectra analyzed by LW-PLS with the new weighting technique was compared with that analyzed by PLS and locally weighted regression (LWR). The RMSEP of LW-PLS with the proposed weighting technique was about 36% and 14% smaller than that of PLS and LWR, respectively, when ibuprofen was a residual drug substance. Similarly, LW-PLS with the weighting technique was about 39% and 24% better than PLS and LWR in RMSEP, respectively, when magnesium stearate was a residual excipient. The combination of IR-RAS and LW-PLS with the proposed weighting technique is a very useful rapid measurement technique of the residual drug substances.
Brown, D. W.; Okuniewski, M. A.; Almer, J. D.; Balogh, L.; Clausen, B.; Okasinski, J. S.; Rabin, B. H.
2013-10-01
Residual stresses are expected in monolithic, aluminum clad uranium 10 wt% molybdenum (U-10Mo) nuclear fuel plates because of the large mismatch in thermal expansion between the two bonded materials. The full residual stress tensor of the U-10Mo foil in a fuel plate assembly was mapped with 0.1 mm resolution using high-energy (86 keV) X-ray diffraction. The in-plane stresses in the U-10Mo foil are strongly compressive, roughly -250 MPa in the longitudinal direction and -140 MPa in the transverse direction near the center of the fuel foil. The normal component of the stress is weakly compressive near the center of the foil and tensile near the corner. The disparity in the residual stress between the two in-plane directions far from the edges and the tensile normal stress suggest that plastic deformation in the aluminum cladding during fabrication by hot isostatic pressing also contributes to the residual stress field. A tensile in-plane residual stress is presumed to be present in the aluminum cladding to balance the large in-plane compressive stresses in the U-10Mo fuel foil, but cannot be directly measured with the current technique due to large grain size.
Residual stresses within sprayed coatings
JIANG Yi; XU Bin-shi; WANG Hai-dou
2005-01-01
Some important developments of residual stress researches for coating-based systems were studied. The following topics were included the sources of residual stresses in coatings: error analysis of Stoney's equation in the curvature method used for the measurement of coating residual stress, the modeling of residual stress and some analytical models for predicting the residual stresses in coatings. These topics should provide some important insights for the fail-safe design of the coating-based systems.
Gao, X.; Klumperink, Eric A.M.; Bohsali, M.; Nauta, Bram
2009-01-01
A clock with low phase-noise/jitter is a prerequisite for high-performance ADCs, wireline and optical data links and radio transceivers. This paper presents a 2.2GHz clock-generation PLL. It uses a phase-detector/charge-pump (PD/CP) that sub-samples the VCO output with the reference clock. The PLL
Comparison of the simulated performance of a VSAT satellite link with measurements
Mwanakatwe, M.; Willis, M. J.; Evans, B. G.
1991-06-01
The transmisson performance of a Ka-band VSAT system (CODE) has been simulated to verify the systems design and to demonstrate the adequacy of the implementation margin and phase noise. A detailed simulation of phase noise effects on VSAT systems design is also presented. Hardware measurements and BOSS simulations for the test set-up show a good agreement for values of Eb/N0 up to 7dB. The simulated results indicate an increased error when the TWTA is operated in the nonlinear region, with the simulations indicating larger degradation than the measurement. The phase noise performance of the digital TRL modem is found to be consistently better than that of the simulated model. There appears to be closer agreement with the BOSS simulations than with the TOPSIM III simulations. The discrepancy between the TOPSIM III and BOSS phase noise simulations was only resolved by measurements taken using the Olympus satellite and BTI satellite simulator.
Zehl, Martin; Rand, Kasper D; Jensen, Ole N;
2008-01-01
show in the present study that electron transfer dissociation in a 3D-quadrupole ion trap retains the site-specific solution-phase deuterium incorporation pattern and allows for localization of incorporated deuterium with single residue resolution. Furthermore, we exploit this finding to monitor how...... collisional activation induces proton mobility in a gaseous peptide ion at various levels of vibrational excitation....
Su, Xun-Cheng; McAndrew, Kerry; Huber, Thomas; Otting, Gottfried
2008-02-06
Lanthanide-binding peptide tags (LBTs) containing a single cysteine residue can be attached to proteins via a disulfide bond, presenting a flexible means of tagging proteins site-specifically with a lanthanide ion. Here we show that cysteine residues placed in different positions of the LBT can be used to expose the protein to different orientations of the magnetic susceptibility anisotropy (delta chi) tensor and to generate different molecular alignments in a magnetic field. Delta chi tensors determined by nuclear magnetic resonance (NMR) spectroscopy for LBT complexes with Yb3+, Tm3+, and Er3+ suggest a rational way of producing alignment tensors with different orientations. In addition, knowledge of the delta chi tensor of LBT allows modeling of the protein-LBT structures. Despite evidence for residual mobility of the LBTs with respect to the protein, the pseudocontact shifts and residual dipolar couplings displayed by proteins disulfide-bonded to LBTs are greater than those achievable with most other lanthanide binding tags.
Zhang, Dongying; Tashiro, Manabu; Shibuya, Katsuhiko; Okamura, Nobuyuki; Funaki, Yoshihito; Yoshikawa, Takeo; Kato, Masato; Yanai, Kazuhiko
2010-12-01
Antihistamines often are self-administered at night as over-the-counter (OTC) sleep aids, but their next-day residual sedative effect has never been evaluated using a reliable quantitative method such as positron emission tomography (PET). We performed a double-blind, placebo-controlled, crossover study in which we evaluated the residual effect the next day after nighttime administration of diphenhydramine, a commonly used OTC sleep aid, in terms of brain H₁ receptor occupancy (H₁RO) measured using ¹¹C-doxepin-PET. We also compared the results of diphenhydramine with those of bepotastine, a second-generation antihistamine. Eight healthy adult male subjects underwent PET measurement the morning (11:00) after random oral administration of diphenhydramine (50 mg), bepotastine (10 mg), or placebo the night before (23:00). Binding potential ratios and H₁ROs were calculated in different brain regions of interest such as the cingulate gyrus, frontotemporal cortex, and cerebellum. Subjective sleepiness and plasma drug concentration also were measured. Calculation of binding potential ratios revealed significantly lower values for diphenhydramine than for bepotastine or placebo in all regions of interest (P drug or the placebo. In conclusion, the next-day residual sedative effect after nighttime administration of the OTC sleep aid diphenhydramine was verified for the first time by direct PET measurement of H₁RO. Taking into account the possible hangover effect of OTC antihistamine sleep aids, care needs to be taken during their administration.
Blyth, T S; Sneddon, I N; Stark, M
1972-01-01
Residuation Theory aims to contribute to literature in the field of ordered algebraic structures, especially on the subject of residual mappings. The book is divided into three chapters. Chapter 1 focuses on ordered sets; directed sets; semilattices; lattices; and complete lattices. Chapter 2 tackles Baer rings; Baer semigroups; Foulis semigroups; residual mappings; the notion of involution; and Boolean algebras. Chapter 3 covers residuated groupoids and semigroups; group homomorphic and isotone homomorphic Boolean images of ordered semigroups; Dubreil-Jacotin and Brouwer semigroups; and loli
Dalafi, A.; Naderi, M. H.
2016-12-01
We theoretically investigate the dispersive interaction of a Bose-Einstein condensate (BEC) trapped inside an optomechanical cavity with a moving end mirror in the presence of the laser phase noise (LPN) as well as the atomic collisions. We assume that the effective frequency of the optical mode is much greater than those of the mechanical and the Bogoliubov modes of the movable mirror and the BEC. In the adiabatic approximation where the damping rate of the cavity is faster than those of the other modes, the system behaves as an effective two-mode model in which the atomic and mechanical modes are coupled to each other through the mediation of the optical field by an effective coupling parameter. We show that in the effective two-mode model, the LPN appears as a classical stochastic pump term which drives the amplitude quadratures of the mechanical and the Bogoliubov modes. It is also shown that a strong stationary mirror-atom entanglement can be established just in the dispersive and Doppler regimes where the two modes come into resonance with each other and the effect of the LPN gets very small.
Jiang, Wenchun; Wei, Zhiquan; Luo, Yun; Zhang, Weiya; Woo, Wanchuck
2016-06-01
This paper uses finite element method and neutron diffraction measurement to study the residual stress in lattice truss sandwich structure. A comparison of residual stress and thermal deformation between X-type and pyramidal lattice truss sandwich structure has been carried out. The residual stresses are concentrated in the middle joint and then decreases gradually to both the ends. The residual stresses in the X-type lattice truss sandwich structure are smaller than those in pyramidal structure. The maximum longitudinal and transverse stresses of pyramidal structure are 220 and 202 MPa, respectively, but they decrease to 190 and 145 MPa for X-type lattice truss sandwich structure, respectively. The thermal deformation for lattice truss sandwich panel structure is of wave shape. The X-type has a better resistance to thermal deformation than pyramidal lattice truss sandwich structure. The maximum wave deformation of pyramidal structure (0.02 mm) is about twice as that of X-type (0.01 mm) at the same brazing condition.
da Luz, Suzane Rickes; Pazdiora, Paulo Cesar; Dallagnol, Leandro José; Dors, Giniani Carla; Chaves, Fábio Clasen
2017-04-01
Wheat (Triticum aestivum) is an annual crop, cultivated in the winter and spring and susceptible to several pathogens, especially fungi, which are managed with fungicides. It is also one of the most consumed cereals, and can be contaminated by mycotoxins and fungicides. The objective of this study was to validate an analytical method by LC-MS for simultaneous determination of mycotoxins and fungicide residues in wheat grains susceptible to fusarium head blight treated with fungicides, and to evaluate the relationship between fungicide application and mycotoxin production. All parameters of the validated analytical method were within AOAC and ANVISA limits. Deoxynivalenol was the prevalent mycotoxin in wheat grain and epoxiconazole was the fungicide residue found in the highest concentration. All fungicidal treatments induced an increase in AFB2 production when compared to the control (without application). AFB1 and deoxynivalenol, on the contrary, were reduced in all fungicide treatments compared to the control.
郑金汪; 陈华; 倪侃; 郭桂良; 张润曦; 刘生有; 来强涛; 阎跃鹏
2014-01-01
Based on 0 .18 μm CMOS process ,a low power low phase noise broadband VCO with low tuning-gain change constant tuning curve interval and constant output swing was presented .Switched capacitor array ,varactor array with bias voltage and the tail current array was included in this VCO .The tuning range of VCO is 1 .153~1.911 GHz(49 .5% ) .The coverage of adjacent tuning curve is more than 50% .The tuning-gain of VCO is 45 .5~52.7 M Hz/V (13 .7% ) .The space of adjacent tuning curve is 43 .2~45 .9 M Hz(5 .9% ) .The output swing of VCO is 694~715 mV(3% ) .The linear range of tuning curve is 0 .2~1 .6 V(1 .4 V) .At a 1 .8 V supply and the center frequency 1 .53 GHz ,the VCO measures a phase noise of-130 .5 dBc/Hz@ 1 MHz offset while dissipating 3 .2 mA current .T he FOM of the VCO is -186 .5 dBc/Hz .%应用 TSMC 0．18μm CMOS工艺设计了一款低调谐增益变化，恒定调谐曲线间隔，恒定输出摆幅的低功耗低噪声宽带压控振荡器（Voltage Controlled Oscillator ，VCO）．本振荡器的振荡频率覆盖1．153～1．911 GHz （49．5％）范围，相邻调谐曲线的覆盖范围大于50％，调谐增益变化范围为45．5～52．7 M Hz/V （13．7％），相邻调谐曲线间距变化范围为43．2～45．9 M Hz（5．9％），VCO输出波形的峰峰值为694～715 mV （3％），调谐曲线的线性范围为0．2～1．6V（1．4V）．在1．8V的电源电压下，VCO在中心频率1．53GHz处耗电电流为3．2mA，相位噪声在1 M Hz频偏处为-130．5 dBc/Hz ，FOM值为-186．5 dBc/Hz ．
Residual Stress Measurement of Gray Iron Braking Disc%灰铸铁制动盘铸件残余应力的测定
陈萌; 彭金花; 杨弋涛
2013-01-01
借助X射线应力仪对不同灰铸铁制动盘铸件进行了应力测试,使用铸造模拟软件ADSTEFAN求解了铸件的残余热应力,结果表明:(1)灰铸铁制动盘铸件进行短时间的自然时效对残余应力没有明显影响；(2)制动盘铸件表面应力分布与其结构和冷却速度均有较大的关联；(3)铸件的弹性模量增加,残余热应力也相应增加,在其余条件不变的情况下,残余热应力与弹性模量呈线性关系；铸件的热膨胀系数增加亦使相应的残余热应力值增加,但不存在明显的线性关系.%The stresses of different gray iron braking discs were measured by using X-ray stress instrument,and the foundry simulation software ADSTEFAN was used to calculate residual thermal stress of the castings.The results showed:(1)natural aging of the gray iron braking disc castings for short time hadn't obvious effect on their residual stresses; (2)there is quite close relationship between the surface stress distribution of the braking disc castings and their configuration as well as their cooling rate; (3)when elastic modulus of castings increasing,their residual stress also increased ;when the other conditions being unchanged,the residual thermal stress and elastic modulus presented a linear relationship;the increasing of thermal expansion coefficient also caused the corresponding residual stress increasing,but they hadn't obvious linear relationship.
Measuring the correlation of two optical frequencies using four-wave mixing.
Anthur, Aravind P; Watts, Regan T; Huynh, Tam N; Venkitesh, Deepa; Barry, Liam P
2014-11-10
We use the physics of four-wave mixing to study the decorrelation of two optical frequencies as they propagate through different fiber delays. The phase noise relationship between the four-wave mixing components is used to quantify and measure the correlation between the two optical frequencies using the correlation coefficient. We show the difference in the evolution of decorrelation between frequency-dependent and frequency-independent components of phase noise.
Albertazzi, A., Jr.; Viotti, M. R.; Kapp, W. A.
2010-08-01
A digital speckle pattern (DSP) interferometer using a special diffractive optical element (DOE) was developed by the authors. A collimated laser beam is diffracted by the DOE in such a way that the first diffraction orders produce a circular double illuminated measurement area. Due to natural symmetry of the illumination scheme, the interferometer reaches pure radial in-plane sensitivity. It is demonstrated and verified that the resulting interferometer is not sensitive to laser wavelength variations at all. Its configuration is presented as well as its performance evaluation for residual stress measurements using the blind hole-drilling method.
Harjo, S.; Sato, Hideo; Tomota, Yo [Ibaraki Univ., Hitachi (Japan). Faculty of Engineering; Ono, Masayoshi
1997-06-01
The testing method of microscopic residual stress in commercial material using neutral diffraction is not established yet like that using x-ray diffraction. Then, in this research a microscopic residual stress of {alpha}/{gamma} two phase Fe-Cr-Ni alloy convenient for an experiment was tried by using neutron diffraction, to investigate its testing method. And further, a test using x-ray diffraction was also conducted for their comparison. As a result, some problems in the residual stress measurement using neutron diffraction were summarized shown as follows. On precision of d{sub 0}, since proper reference material was difficult for material M to provide, a preferable result could not be obtained in the stress measurement using PSD method. On curve fitting, by changing from a multi order function to a Voigt function by using the curve-fitting method, it was found that the peak could be fit better. Furthermore, on the problem of testing condition, because of weak intensity of the neutron source, it was necessary to use a monochromator capable of collecting incident beam like Bent crystal, and to improve sample setting, counter and slit. (G.K.)
Oh, Won Sup; Chon, Sung-Bin
2016-05-01
Fluid resuscitation, hemostasis, and transfusion is essential in care of hemorrhagic shock. Although estimation of the residual blood volume is crucial, the standard measuring methods are impractical or unsafe. Vital signs, central venous or pulmonary artery pressures are inaccurate. We hypothesized that the residual blood volume for acute, non-ongoing hemorrhage was calculable using serial hematocrit measurements and the volume of isotonic solution infused. Blood volume is the sum of volumes of red blood cells and plasma. For acute, non-ongoing hemorrhage, red blood cell volume would not change. A certain portion of the isotonic fluid would increase plasma volume. Mathematically, we suggest that the residual blood volume after acute, non-ongoing hemorrhage might be calculated as 0·25N/[(Hct1/Hct2)-1], where Hct1 and Hct2 are the initial and subsequent hematocrits, respectively, and N is the volume of isotonic solution infused. In vivo validation and modification is needed before clinical application of this model.
Brown, D. W.; Okuniewski, M. A.; Sisneros, T. A.; Clausen, B.; Moore, G. A.; Balogh, L.
2016-12-01
Al clad U-10Mo fuel plates are being considered for conversion of several research reactors from high-enriched to low-enriched U fuel. Neutron diffraction measurements of the textures, residual phase stresses, and dislocation densities in the individual phases of the mini-foils throughout several processing steps and following hot-isostatic pressing to the Al cladding, have been completed. Recovery and recrystallization of the bare U-10Mo fuel foil, as indicated by the dislocation density and texture, are observed depending on the state of the material prior to annealing and the duration and temperature of the annealing process. In general, the cladding procedure significantly reduces the dislocation density, but the final state of the clad plate, both texture and dislocation density, depends strongly on the final processing step of the fuel foil. In contrast, the residual stress state of the final plate is dominated by the thermal expansion mismatch of the constituent materials.
Maiti, Moumita
2011-01-01
Production cross sections of evaporation residues, $^{149}$Tb, $^{150}$Tb, $^{151}$Tb and $^{149}$Gd, have been measured using the stacked foil technique followed by off-line $\\gamma$-spectrometry in $^{12}$C induced reactions on naturally abundant mononuclidic praseodymium target in the 44-79 MeV incident energy range. Measured data have been interpreted comparing with previous measurements and theoretical prediction of nuclear reaction model code \\textsc{PACE4}. About 5% and 14% of the theoretical cross sections have been measured for $^{149}$Tb and $^{150}$Tb, respectively. The new cross sections of $^{149}$Tb complement those measured earlier by $\\alpha$-spectrometry. Cross sections of $^{151}$Tb are comparable to the theory. Cumulative cross section of $^{149}$Gd sheds light on the nuclear reaction mechanism. In addition, a discussion has been made to show the feasibility of producing $^{149}$Tb in $p$- and $\\alpha$-induced reactions on gadolinium isotopes.
Towne, Victoria; Oswald, C Brent; Mogg, Robin; Antonello, Joseph; Will, Mark; Gimenez, Juan; Washabaugh, Michael; Sitrin, Robert; Zhao, Qinjian
2009-11-01
Quantitation of residual hydrogen peroxide (H(2)O(2)) and evaluation of the impact on product stability is necessary as unwanted H(2)O(2) can potentially be introduced during the manufacturing of pharmaceuticals, biologics, and vaccines. A sensitive and convenient microplate-based method with fluorescence detection for H(2)O(2) quantitation was recently reported (Towne et al., 2004, Anal Biochem 334: 290-296). This method was found to be highly robust and reproducible, with a level of detection of 0.015 ppm and a level of quantitation of 0.025 ppm (in water). The relatively small sample requirements and amenability for automation make this assay an attractive tool for detecting residual H(2)O(2) levels. Without additional manipulation, the assay can be conducted on heterogeneous solutions with significant degree of turbidity, such as the presence of suspensions or aluminum-containing adjuvants. The quantitation of H(2)O(2) and its decomposition kinetics was also studied in presence of two common vaccine preservatives (thimerosal and phenol) and eight commonly used excipients (polyols). Over time, there is a distinct, temperature dependent decrease in H(2)O(2) recovered in thimerosal and phenol containing samples versus non-preservative containing controls. Based on the half-life of spiked H(2)O(2), the decay rates in eight polyols tested were found to be: ribose > sucrose > (glycerol, glucose, lactose, mannitol, sorbitol, and xylose).
Direct real-time quantitative PCR for measurement of host-cell residual DNA in therapeutic proteins.
Peper, Grit; Fankhauser, Alexander; Merlin, Thomas; Roscic, Ana; Hofmann, Matthias; Obrdlik, Petr
2014-11-01
Real-time quantitative PCR (qPCR) is important for quantification of residual host cell DNA (resDNA) in therapeutic protein preparations. Typical qPCR protocols involve DNA extraction steps complicating sample handling. Here, we describe a "direct qPCR" approach without DNA extraction. To avoid interferences of DNA polymerase with a therapeutic protein, proteins in the samples were digested with proteinase K (PK) in the presence of sodium dodecyl sulfate (SDS). Tween 20 and NaCl were included to minimize precipitation of therapeutic proteins in the PK/SDS mix. After PK treatment, the solution was applied directly for qPCR. Inhibition of DNA polymerase by SDS was prevented by adding 2% (v/v) of Tween 20 to the final qPCR mix. The direct qPCR approach was evaluated for quantification of resDNA in therapeutic proteins manufactured in Chinese hamster ovary (CHO) host cells. First, direct qPCR was compared with qPCR applied on purified DNA ("extraction qPCR"). For both qPCRs, the same CHO-specific primers and probes were used. Comparable residual DNA levels were detected with both PCR approaches in purified and highly concentrated drug proteins as well as in in-process-control samples. Finally, the CHO-specific direct qPCR protocol was validated according to ICH guidelines and applied for 25 different therapeutic proteins. The specific limits of quantification were 0.1-0.8ppb for 24 proteins, and 2.0ppb for one protein. General applicability of the direct qPCR was demonstrated by applying the sample preparation protocol for quantification of resDNA in therapeutic proteins manufactured in other hosts such as Escherichia coli and mouse cells.
Brown, Donald W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Okuniewski, M. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sisneros, Thomas A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Clausen, Bjorn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moore, G. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Balogh, L [Queen' s Univ., Kingston, ON (Canada)
2014-08-07
Aluminum clad monolithic uranium 10 weight percent molybdenum (U-10Mo) fuel plates are being considered for conversion of several research and test nuclear reactors from high-enriched to low-enriched uranium fuel due to the inherently high density of fissile material. Comprehensive neutron diffraction measurements of the evolution of the textures, residual phase stresses, and dislocation densities in the individual phases of the mini-foils throughout several processing steps and following hot-isostatic pressing to the Al cladding, have been completed. Recovery and recrystallization of the bare U-10Mo fuel foil, as indicated by the dislocation density and texture, are observed depending on the state of the material prior to annealing and the duration and temperature of the annealing process. In general, the HIP procedure significantly reduces the dislocation density, but the final state of the clad plate, both texture and dislocation density, depends strongly on the final processing step of the fuel foil. In contrast, the residual stresses in the clad fuel plate do not depend strongly on the final processing step of the bare foil prior to HIP bonding. Rather, the residual stresses are dominated by the thermal expansion mismatch of the constituent materials of the fuel plate.
Fowler, Justin; Li, Wei; Bailey, Christopher
2015-08-26
Research has shown success using clay-based binders to adsorb aflatoxin in animal feeds; however, no adsorbent has been approved for the prevention or treatment of aflatoxicosis. In this study, growth and relative organ weights were evaluated along with a residue analysis for aflatoxin B₁ in liver tissue collected from broiler chickens consuming dietary aflatoxin (0, 600, 1200, and 1800 µg/kg) both with and without 0.2% of a calcium bentonite clay additive (TX4). After one week, only the combined measure of a broiler productivity index was significantly affected by 1800 µg/kg aflatoxin. However, once birds had consumed treatment diets for two weeks, body weights and relative kidney weights were affected by the lowest concentration. Then, during the third week, body weights, feed conversion, and the productivity index were affected by the 600 µg/kg level. Results also showed that 0.2% TX4 was effective at reducing the accumulation of aflatoxin B₁ residues in the liver and improving livability in birds fed aflatoxin. The time required to clear all residues from the liver was less than one week. With evidence that the liver's ability to process aflatoxin becomes relatively efficient within three weeks, this would imply that an alternative strategy for handling aflatoxin contamination in feed could be to allow a short, punctuated exposure to a higher level, so long as that exposure is followed by at least a week of a withdrawal period on a clean diet free of aflatoxin.
S. Balaguru
2016-01-01
Full Text Available In sodium-cooled fast reactors (SFR, grid plate is a critical component which is made of 316 L(N SS. It is supported on core support structure. The grid plate supports the core subassemblies and maintains their verticality. Most of the components of SFR are made of 316 L(N/304 L(N SS and they are in contact with the liquid-metal sodium which acts as a coolant. The peak operating temperature in SFR is 550°C. However, the self-welding starts at 500°C. To avoid self-welding and galling, hardfacing of the grid plate has become necessary. Nickel based cobalt-free colmonoy 5 has been identified as the hardfacing material due to its lower dose rate by Plasma Transferred Arc Welding (PTAW. This paper is concerned with the measurement and investigations of the effects of the residual stress generated due to thermal cycling on a scale-down physical model of the grid plate. Finite element analysis of the hardfaced grid plate model is performed for obtaining residual stresses using elastoplastic analysis and hence the results are validated. The effects of the residual stresses due to thermal cycling on the hardfaced grid plate model are studied.
Filbey, Francesca M; Aslan, Sina; Lu, Hanzhang; Peng, Shin-Lei
2017-03-22
Given the known vascular effects of cannabis, this study examined the neurophysiological factors that may affect studies of brain activity in cannabis users. We conducted a systematic evaluation in 72 h abstinent, chronic cannabis users (N=74) and nonusing controls (N=101) to determine the association between prolonged cannabis use and the following neurophysiological indicators: (1) global and regional resting cerebral blood flow (CBF), (2) oxygen extraction fraction (OEF), and (3) cerebral metabolic rate of oxygen (CMRO2). We found that cannabis users had greater global OEF and CMRO2 compared with nonusers. Regionally, we found higher CBF in the right pallidum/putamen of the cannabis users compared with nonusers. Global resting CBF and regional CBF of right superior frontal cortex correlated positively with creatinine-normalized Δ9-tetrahydrocannabinol (THC) levels. These findings demonstrate residual effects of cannabis use whereby global and regional brain metabolism are altered in those with prolonged cannabis exposure. These neurophysiological alterations should be considered in both research and clinical applications.Neuropsychopharmacology advance online publication, 22 March 2017; doi:10.1038/npp.2017.44.
Hu, B; Sellers, J; Kupec, J; Ngo, W; Fenton, S; Yang, T-Y; Grebanier, A
2014-01-01
Host cell DNA contamination occurs during the production of biopharmaceuticals and must be controlled and monitored for the purity and safety of the drug products. A sodium iodide-based DNA extraction and a subsequent real time PCR assay were developed and validated for the quantitative measurement of residual host cell DNA impurity in monoclonal antibody therapeutic products. A sodium iodide-based commercial kit was optimized for the removal of interfering matrices. Several incubation steps from the kit protocol were combined and a neutralization buffer was introduced to protein digestion step to eliminate any precipitation from the detergent. The elimination of the two washing steps significantly reduced assay variability from loss of DNA pellets. The optimized DNA extraction procedure can recover DNA close to 100% for DNA concentrations from 10 to 100,000pg/mL. Of the published sequences of repetitive interspersed nuclear elements, we identified a nucleotide mismatch from the published CHO probe. Correction of this nucleotide increased DNA amplification by a thousand fold. The optimized assay was further validated for the quantitation of residual CHO DNA according to ICH guidelines with preset assay acceptance criteria. The method met all assay acceptance criteria and was found linear, accurate and precise for the quantitation of residual CHO in the linear range of 10-100,000pg DNA/mL. LOQ was measured at 10pg DNA/mL and LOD at 1pg DNA/mL. No matrix interference to our validated assay was detected from bioreactor harvest, Protein A eluate or eluate from ion exchange columns.
Bousoumah, Radia; Antignac, Jean Philippe; Camel, Valérie; Grimaldi, Marina; Balaguer, Patrick; Courant, Frederique; Bichon, Emmanuelle; Morvan, Marie-Line; Le Bizec, Bruno
2015-11-01
Multi-residue methods permitting the high-throughput and affordable simultaneous determination of an extended range of endocrine disrupting chemicals (EDCs) with reduced time and cost of analysis is of prime interest in order to characterize a whole set of bioactive compounds. Such a method based on UHPLC-MS/MS measurement and dedicated to 13 estrogenic EDCs was developed and applied to biological matrices. Two molecular recognition-based strategies, either molecular imprinted polymer (MIP) with phenolic template or estrogen receptors (ERα) immobilized on a sorbent, were assessed in terms of recovery and purification efficiency. Both approaches demonstrated their suitability to measure ultra-trace levels of estrogenic EDCs in aqueous samples. Applicability of the MIP procedure to urine and serum samples has also been demonstrated.
Apollonio, A; Solfaroli, M; Schmidt, R; Verweij, A
2012-01-01
After the incident of September 2008, the operational beam energy of the LHC has been set to 3.5 TeV, since not all joints of the superconducting busbars between magnets have the required quality for 7 TeV operation. This choice is based on simulations to determine the safe current in the main dipole and quadrupole magnets, reproducing the thermal behavior of a quenched superconducting joint by taking into account all relevant factors that affect a possible thermal runaway. One important parameter of the simulation is the RRR (Residual Resistivity Ratio) of the copper stabilizer of the busbar connecting superconducting magnets. A dedicated campaign to measure this quantity for the main 13kA circuits of the LHC on all sectors was performed during the Christmas stop in December 2010 and January 2011. The measurement method as well as the data analysis and results are presented in this note.
Apollonio, A; Solfaroli Camillocci, M; Schmidt, R; Verweij, A; Siemko, A; Claudet, S; Steckert, J; Thiesen, H
2012-01-01
After the incident of September 2008, the operational beam energy of the LHC has been set to 3.5 TeV, since not all joints of the superconducting (SC) bus bars between magnets have the required quality for 7 TeV operation. This decision is based on simulations to determine the safe current in the main dipole and quadrupole circuits, reproducing the thermal behaviour of a quenched superconducting joint by taking into account all relevant factors that affect a possible thermal runaway. One important parameter is the Residual Resistivity Ratio (RRR) of the copper stabilizer of the bus bar connecting the superconducting magnets. A dedicated campaign to measure the RRR for the main 13 kA circuits of the LHC in all sectors was performed during the Christmas stop in December 2010 and January 2011. The measurement method as well as the data analysis and results are presented in this paper.
Nath, Nilamoni; Suryaprakash, N
2011-06-02
We report the C-HETSERF experiment for determination of long- and short-range homo- and heteronuclear scalar couplings ((n)J(HH) and (n)J(XH), n ≥ 1) of organic molecules with a low sensitivity dilute heteronucleus in natural abundance. The method finds significant advantage in measurement of relative signs of long-range heteronuclear total couplings in chiral organic liquid crystal. The advantage of the method is demonstrated for the measurement of residual dipolar couplings (RDCs) in enantiomers oriented in the chiral liquid crystal with a focus to unambiguously assign R/S designation in a 2D spectrum. The alignment tensor calculated from the experimental RDCs and with the computed structures of enantiomers obtained by DFT calculations provides the size of the back-calculated RDCs. Smaller root-mean-square deviations (rmsd) between experimental and calculated RDCs indicate better agreement with the input structure and its correct designation of the stereogenic center.
An upgraded interferometer-polarimeter system for broadband fluctuation measurements
Parke, E., E-mail: eparke@ucla.edu; Ding, W. X.; Brower, D. L. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States); Duff, J. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
2016-11-15
Measuring high-frequency fluctuations (above tearing mode frequencies) is important for diagnosing instabilities and transport phenomena. The Madison Symmetric Torus interferometer-polarimeter system has been upgraded to utilize improved planar-diode mixer technology. The new mixers reduce phase noise and allow more sensitive measurements of fluctuations at high frequency. Typical polarimeter rms phase noise values of 0.05°–0.07° are obtained with 400 kHz bandwidth. The low phase noise enables the resolution of fluctuations up to 250 kHz for polarimetry and 600 kHz for interferometry. The importance of probe beam alignment for polarimetry is also verified; previously reported tolerances of ≤0.1 mm displacement for equilibrium and tearing mode measurements minimize contamination due to spatial misalignment to within acceptable levels for chords near the magnetic axis.
Justin Fowler
2015-08-01
Full Text Available Research has shown success using clay-based binders to adsorb aflatoxin in animal feeds; however, no adsorbent has been approved for the prevention or treatment of aflatoxicosis. In this study, growth and relative organ weights were evaluated along with a residue analysis for aflatoxin B1 in liver tissue collected from broiler chickens consuming dietary aflatoxin (0, 600, 1200, and 1800 µg/kg both with and without 0.2% of a calcium bentonite clay additive (TX4. After one week, only the combined measure of a broiler productivity index was significantly affected by 1800 µg/kg aflatoxin. However, once birds had consumed treatment diets for two weeks, body weights and relative kidney weights were affected by the lowest concentration. Then, during the third week, body weights, feed conversion, and the productivity index were affected by the 600 µg/kg level. Results also showed that 0.2% TX4 was effective at reducing the accumulation of aflatoxin B1 residues in the liver and improving livability in birds fed aflatoxin. The time required to clear all residues from the liver was less than one week. With evidence that the liver’s ability to process aflatoxin becomes relatively efficient within three weeks, this would imply that an alternative strategy for handling aflatoxin contamination in feed could be to allow a short, punctuated exposure to a higher level, so long as that exposure is followed by at least a week of a withdrawal period on a clean diet free of aflatoxin.
Fowler, Justin; Li, Wei; Bailey, Christopher
2015-01-01
Research has shown success using clay-based binders to adsorb aflatoxin in animal feeds; however, no adsorbent has been approved for the prevention or treatment of aflatoxicosis. In this study, growth and relative organ weights were evaluated along with a residue analysis for aflatoxin B1 in liver tissue collected from broiler chickens consuming dietary aflatoxin (0, 600, 1200, and 1800 µg/kg) both with and without 0.2% of a calcium bentonite clay additive (TX4). After one week, only the combined measure of a broiler productivity index was significantly affected by 1800 µg/kg aflatoxin. However, once birds had consumed treatment diets for two weeks, body weights and relative kidney weights were affected by the lowest concentration. Then, during the third week, body weights, feed conversion, and the productivity index were affected by the 600 µg/kg level. Results also showed that 0.2% TX4 was effective at reducing the accumulation of aflatoxin B1 residues in the liver and improving livability in birds fed aflatoxin. The time required to clear all residues from the liver was less than one week. With evidence that the liver’s ability to process aflatoxin becomes relatively efficient within three weeks, this would imply that an alternative strategy for handling aflatoxin contamination in feed could be to allow a short, punctuated exposure to a higher level, so long as that exposure is followed by at least a week of a withdrawal period on a clean diet free of aflatoxin. PMID:26343723
Antoni, R.; Passard, C.; Perot, B.; Batifol, M.; Vandamme, J.C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 St Paul-lez-Durance, (France); Grassi, G. [AREVA NC, 1 place Jean-Millier, 92084 Paris-La-Defense cedex (France)
2015-07-01
The fissile mass in radioactive waste drums filled with compacted metallic residues (spent fuel hulls and nozzles) produced at AREVA La Hague reprocessing plant is measured by neutron interrogation with the Differential Die-away measurement Technique (DDT. In the next years, old hulls and nozzles mixed with Ion-Exchange Resins will be measured. The ion-exchange resins increase neutron moderation in the matrix, compared to the waste measured in the current process. In this context, the Nuclear Measurement Laboratory (NML) of CEA Cadarache has studied a matrix effect correction method, based on a drum monitor ({sup 3}He proportional counter inside the measurement cavity). A previous study performed with the NML R and D measurement cell PROMETHEE 6 has shown the feasibility of method, and the capability of MCNP simulations to correctly reproduce experimental data and to assess the performances of the proposed correction. A next step of the study has focused on the performance assessment of the method on the industrial station using numerical simulation. A correlation between the prompt calibration coefficient of the {sup 239}Pu signal and the drum monitor signal was established using the MCNPX computer code and a fractional factorial experimental design composed of matrix parameters representative of the variation range of historical waste. Calculations have showed that the method allows the assay of the fissile mass with an uncertainty within a factor of 2, while the matrix effect without correction ranges on 2 decades. In this paper, we present and discuss the first experimental tests on the industrial ACC measurement system. A calculation vs. experiment benchmark has been achieved by performing dedicated calibration measurement with a representative drum and {sup 235}U samples. The preliminary comparison between calculation and experiment shows a satisfactory agreement for the drum monitor. The final objective of this work is to confirm the reliability of the
Experimental determination of residual stress
Ferguson, Milton W.
1991-01-01
Residual stresses in finished parts have often been regarded as factors contributing to premature part failure and geometric distortions. Currently, residual stresses in welded structures and railroad components are being investigated. High residual stresses formed in welded structures due primarily to the differential contractions of the weld material as it cools and solidifies can have a profound effect on the surface performance of the structure. In railroad wheels, repeated use of the brakes causes high residual stresses in the rims which may lead to wheel failure and possible derailment. The goals of the study were: (1) to develop strategies for using x-ray diffraction to measure residual stress; (2) to subject samples of Inconel 718 to various mechanical and heat treatments and to measure the resulting stress using x-ray diffraction; and (3) to measure residual stresses in ferromagnetic alloys using magnetoacoustics.
Bredahl, Kim; Taudorf, M; Long, A
2013-01-01
Discrepancy between maximum diameters obtained with two-dimensional ultrasound and computed tomography (CT) after endovascular aneurysm repair (EVAR) is well known. The maximal diameter is ideally measured perpendicular to the centerline, a methodology so far only feasible with three-dimensional ...
Sorooshian, A.; Wang, Z.; Coggon, M.; Craven, J. S.; Metcalf, A. R.; Lin, J. J.; Nenes, A.; Jonsson, H.; Flagan, R. C.; Seinfeld, J.
2012-12-01
During the July-August 2012 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter carried out thirty flights off the California coast with a payload focused on detailed characterization of aerosol and cloud properties. A counter-flow virtual impactor (CVI) inlet was used in cloud to study the physical and chemical properties of drop residual particles in the climatically-important stratocumulus cloud deck over the northeastern Pacific Ocean. A total of 82 cloud water samples were also collected and examined with ion chromatography (17 anion species) and inductively coupled plasma mass spectrometry (> 50 elements). The pH of the cloud water samples ranged widely between 2.92 and 7.58. This work focuses on inter-relationships between the chemical signatures of cloud water and drop residual particles, in addition to the influence of numerous regional sources on these measurements. Of interest will be to look critically at the influence of biogenic oceanic sources, shipping traffic, and entrainment of free tropospheric aerosol.
Li, C; Jacques, S D M; Chen, Y; Daisenberger, D; Xiao, P; Markocsan, N; Nylen, P; Cernik, R J
2016-12-01
The average residual stress distribution as a function of depth in an air plasma-sprayed yttria stabilized zirconia top coat used in thermal barrier coating (TBC) systems was measured using synchrotron radiation X-ray diffraction in reflection geometry on station I15 at Diamond Light Source, UK, employing a series of incidence angles. The stress values were calculated from data deconvoluted from diffraction patterns collected at increasing depths. The stress was found to be compressive through the thickness of the TBC and a fluctuation in the trend of the stress profile was indicated in some samples. Typically this fluctuation was observed to increase from the surface to the middle of the coating, decrease a little and then increase again towards the interface. The stress at the interface region was observed to be around 300 MPa, which agrees well with the reported values. The trend of the observed residual stress was found to be related to the crack distribution in the samples, in particular a large crack propagating from the middle of the coating. The method shows promise for the development of a nondestructive test for as-manufactured samples.
Martin-Pastor, Manuel [Universidad de Santiago de Compostela, Laboratorio Integral de Estructura de Biomoleculas Jose. R. Carracido, Unidade de Resonancia Magnetica, RIAIDT (Spain)], E-mail: mmartin@usc.es; Canales-Mayordomo, Angeles; Jimenez-Barbero, Jesus [Departamento de Estructura y funcion de proteinas, Centro de Investigaciones Biologicas, CSIC (Spain)], E-mail: jjbarbero@cib.csic.es
2003-08-15
A 2D-HSQC-carbon selective/proton selective-constant time COSY, 2D-HSQC-(sel C, sel H)-CT COSY experiment, which is applicable to uniformly {sup 13}C isotopically enriched samples (U-{sup 13}C) of oligosaccharides or oligonucleotides is proposed for the measurement of proton-proton RDC in crowded regions of 2D-spectra. In addition, a heteronuclear constant time-COSY experiment, {sup 13}C-{sup 13}C CT-COSY, is proposed for the measurement of one bond carbon-carbon RDC in these molecules. These two methods provide an extension, to U-{sup 13}C molecules, of the original homonuclear constant time-COSY experiment proposed by Tian et al. (1999) for saccharides. The combination of a number of these RDC with NOE data may provide the method of choice to study oligosaccharide conformation in the free and receptor-bound state.
刘继红
2012-01-01
The negative effects of laser phase noise on the performance of carrier phase estimation and choosing optimized modulation formats for optical coherent communication systems are analyzed. Simulation results show that: For 16-QAM coherent optical fiber communication systems, star constellation has higher tolerance on laser phase noise than that of square constellation because the position of the points in star constellation can be changed according to the properties of system noises; the length of symbol blocks for averaging in the algorithm of Viterbi-Viterbi carrier phase estimation is inversely proportional to the value of laser phase noise; at a certain BER, the required bit number of analog-to-digital converters in optical coherent receivers does not depend on the modulation formats and their levels.%研究了激光相位噪声对相干光纤通信系统调制格式选择、参数优化和载波相位估计性能等的影响,仿真研究表明：对于16-QAM相干光纤通信系统,star型星座图中星点位置关系可以依据系统噪声特性优化,具有比square型星座图更大的激光相位噪声容限;经典的Viterbi-Viterbi载波相位估计方法用于相干光纤通信系统时,算法中对符号序列平均的最佳长度与激光相位噪声成反比;对于一定的目标误比特率,相干光接收机中A/D有效位数的大小与系统调制格式阶数和星座图特征基本无关。