• 제목/요약/키워드: zero-error

검색결과 754건 처리시간 0.027초

GAIA PARALLAX ZERO POINT FROM RR LYRAE STARS

  • Gould, Andrew;Kollmeier, Juna A.
    • 천문학회지
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    • 제50권1호
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    • pp.1-5
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    • 2017
  • Like Hipparcos, Gaia is designed to give absolute parallaxes, independent of any astrophysical reference system. And indeed, Gaia's internal zero-point error for parallaxes is likely to be smaller than any individual parallax error. Nevertheless, due in part to mechanical issues of unknown origin, there are many astrophysical questions for which the parallax zero-point error ${\sigma}({\pi}_0)$ will be the fundamentally limiting constraint. These include the distance to the Large Magellanic Cloud and the Galactic Center. We show that by using the photometric parallax estimates for RR Lyrae stars (RRL) within 8kpc, via the ultra-precise infrared period-luminosity relation, one can independently determine a hyper-precise value for ${\pi}_0$. Despite their paucity relative to bright quasars, we show that RRL are competitive due to their order-of-magnitude improved parallax precision for each individual object relative to bright quasars. We show that this method is mathematically robust and well-approximated by analytic formulae over a wide range of relevant distances.

구리와 코디에라이트와의 접촉점에서 구리에 대한 ESCA 스펙트럼의 에너지 교정 (Energy Calibration of ESCA Spectrum for the Copper in the Interface of Copper and Cordierite)

  • Han, Byoung-Sung
    • 대한전자공학회논문지
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    • 제25권1호
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    • pp.27-32
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    • 1988
  • Electron Spectroscopy for Chemical Analysis(ESCA) allowes the determination of the elemental composition and the bonding state of the surface atomes in the interface between two materials. In the binding energies of ESCA spectrum, there are zero error, voltage scaling error and random error. Accurate analysis of the intensity energy response functions and accurate calibration of the energy scale are essential to use X-ray photoelectron spectron meter. At the results of the calibration of the ESCA spectra in the copper and cordierite (Mg2Al4Si5kO18) interfaces, the errors relative to the copper are -3.03 eV for the zero error -z,-197 ppm for the voltage scaling error -V and 6.9 meV for the random error -R. The method of the calibration is able to apply for the binding energy calibration of the another ESCA spectra.

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Sensorless Control of Non-salient Permanent Magnet Synchronous Motor Drives using Rotor Position Tracking PI Controller

  • Lee Jong-Kun;Seok Jul-Ki
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • 제5B권2호
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    • pp.189-195
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    • 2005
  • This paper presents a new velocity estimation strategy for a non-salient permanent magnet synchronous motor drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system, which contains the rotor position error information. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error at zero. For zero and low speed operation, the PI gain of the rotor position tracking controller has a variable structure according to the estimated rotor velocity. Then, at zero speed, the rotor position and velocity have sluggish dynamics because the varying gains are very low in this region. In order to boost the bandwidth of the PI controller during zero speed, the loop recovery technique is applied to the control system. The PI tuning formulas are also derived by analyzing this control system by frequency domain specifications such as phase margin and bandwidth assignment.

영오차 확률 기반 알고리즘의 입력 정력 정규화 (Input Power Normalization of Zero-Error Probability based Algorithms)

  • 김종일;김남용
    • 한국통신학회논문지
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    • 제42권1호
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    • pp.1-7
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    • 2017
  • 충격성 잡음 환경에서 최대 영확률 (MZEP) 알고리듬은 최소자승오차 (MSE) 기반의 알고리듬 보다 우수한 성능을 지닌다. 그리고 알고리듬 자체에 내재한 크기 조절 입력 (MCI)가 MZEP 알고리듬을 충격성 잡음으로부터 알고리듬을 안정되게 유지하는 역할을 하는 것으로 알려져 있다. 이 논문에서는 MCI 입력의 평균전력으로 MZEP 알고리듬의 스텝 사이즈를 정규화하는 방식을 제안하였다. 충격파 발생률이 0.03인 충격성 잡음하의 시뮬레이션에서 정상상태 MSE 성능 비교에서 기존 MZEP에 비해 제안한 방식이 약 2dB 정도 향상된 특성을 보인다.

An Ordered Successive Interference Cancellation Scheme in UWB MIMO Systems

  • An, Jin-Young;Kim, Sang-Choon
    • ETRI Journal
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    • 제31권4호
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    • pp.472-474
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    • 2009
  • In this letter, an ordered successive interference cancellation (OSIC) scheme is applied for multiple-input multiple-output (MIMO) detection in ultra-wideband (UWB) communication systems. The error rate expression of an OSIC receiver on a log-normal multipath fading channel is theoretically derived in a closed form solution. Its bit error rate performance is analytically compared with that of a zero forcing receiver in the UWB MIMO detection scheme followed by RAKE combining.

영점구조를 이용한 비 최소위상 플랜트의 새로운 LQG/LTR 방법연구 (A study on a new method of LQG/LTR for nonminimum phase plant by using zero structure)

  • 서병설;강진식
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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    • pp.208-212
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    • 1991
  • LQG/LTR method cannot applied to nonminimum phase plant. In this paper, we present a new approximation method which guaratee the approximation error equal to zero and exact loop transfer recovery. Zero structure of plant and approximated plant are considered in approximation procedure. It is shown that the properties of plant and approximated plant at pole and zero frequency response are exactly same. It is shown by example that the suggested method can avoide the NMP plant constraint arised in designing LQG/LTR.

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Analysis of Proportional Control for Grid Connected Inverter With LCL Filter

  • Windarko, Novie Ayub;Lee, Jin-Mok;Choi, Jae-Ho
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2008년도 하계학술대회 논문집
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    • pp.247-249
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    • 2008
  • There are many types of grid-connected inverter controllers; Synchronous Reference Frame (SRF)-based controller is the most popular methods. SRF-based controller is capable for reducing both of zero-steady state error and phase delay. However, SRF-based controller has a complex algorithm to apply in real application such as digital processor. Resonant controller is also reduced zero-steady state error, but its transfer function has a high order. In this paper, a simple proportional control is applied for grid connected inverter with LCL filter. LCL filter is a third order system. Applying a simple proportional controller is not increased the order of closed loop transfer function. By this technique, the single phase model is easily obtained. To reduce steady state error, proportional gain is set as high as possible, but it may produce instability. To compromise between a minimum steady state error and stability, the single phase model is evaluate through Root Locus and Bode diagram. PSIM simulation is used to verify the analysis.

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ERROR BOUNDS OF TRAPEZOIDAL RULE ON SUBINTERVALS USING DISTRIBUTION

  • Hong, Bum-Il;Hahm, Nahm-Woo
    • 호남수학학술지
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    • 제29권2호
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    • pp.245-257
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    • 2007
  • We showed in [2] that if $r\leq2$, then the average error between simple Trapezoidal rule and the composite Trapezoidal rule on two consecutive subintervals is proportional to $h^{2r+3}$ using zero mean Gaussian distribution under the assumption that we have subintervals (for simplicity equal length) partitioning and that each subinterval has the length. In this paper, if $r\geq3$, we show that zero mean Gaussian distribution of average error between simple Trapezoidal rule and the composite Trapezoidal rule on two consecutive subintervals is bounded by $Ch^8$.

광디스크 드라이브를 위한 강인 제어기 설계 (Robust Servo System for Optical Disk Drive Systems)

  • 박범호;정정주;표현봉;박용우
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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    • pp.380-383
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    • 2003
  • This paper proposes a new and simple input prediction method for robust servo system. This servo system uses robust tracking control system based on both Coprime Factorization(CF) and Zero Phase Error Tracking control system. The CF control system can be designed simply and systematically. Moreover, this system has not only stability but also robustness and disturbance rejection ability The optical disk tracking servo system can detect only the tracking error. So the new and simple input prediction system proposed in this paper estimates the reference input signal from the tracking error. Numerical simulation results show that the proposed method is effective.

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이산화 오차를 고려한 ZCP 추정방법과 고속 BLDC 센서리스 구동에 관한 연구 (A Study of the ZCP Estimation Methods considering Discretization Error and High Speed BLDC Sensorless Drive)

  • 서은정;손정원;선우명호;이우택
    • 한국자동차공학회논문집
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    • 제22권1호
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    • pp.95-102
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    • 2014
  • This paper presents zero crossing point(ZCP) estimation methods considering discretization error for a high speed brushless DC(BLDC) motor drive. The ZCP is estimated by detecting the change of back-EMF polarity for the BLDC sensorless drive, and the discretization error exist on the estimated ZCP. The discretization error of the ZCP is a cause of the delay of a commutation timing of current and increment of a current ripple factor. Besides a delay of a ZCP estimation brings on the limitation of a speed range for the BLDC sensorless drive. The compensation method based on the error analysis with probability theory for reducing the effects of the discretization error of the ZCP is proposed. Also a ZCP estimation method according to the Back-EMF patterns is proposed to widen the speed range for the BLDC sensorless drive. The proposed methods are verified by the experiment.