• Title/Summary/Keyword: Pseudo Function

Search Result 328, Processing Time 0.023 seconds

Proposed dynamic p-y curves on a single pile considering shear wave velocity of soil

  • Song, Sumin;Lim, Hyunsung;Park, Seongyong;Jeong, Sangseom
    • Earthquakes and Structures
    • /
    • v.23 no.4
    • /
    • pp.353-361
    • /
    • 2022
  • The dynamic behavior of a single pile was investigated by using analytical and numerical studies. The focus of this study was to develop the dynamic p-y curve of a pile for pseudo-static analysis considering the shear wave velocity of the soil by using three-dimensional numerical analyses. Numerical analyses were conducted for a single pile in dry sand under changing conditions such as the shear wave velocity of the soil and the acceleration amplitudes. The proposed dynamic p-y curve is a shape of hyperbolic function that was developed to take into account the influence of the shear wave velocity of soil. The applicability of pseudo-static analysis using the proposed dynamic p-y curve shows good agreement with the general trends observed by dynamic analysis. Therefore, the proposed dynamic p-y curve represents practical improvements for the seismic design of piles.

Finding Pseudo Periods over Data Streams based on Multiple Hash Functions (다중 해시함수 기반 데이터 스트림에서의 아이템 의사 주기 탐사 기법)

  • Lee, Hak-Joo;Kim, Jae-Wan;Lee, Won-Suk
    • Journal of Information Technology Services
    • /
    • v.16 no.1
    • /
    • pp.73-82
    • /
    • 2017
  • Recently in-memory data stream processing has been actively applied to various subjects such as query processing, OLAP, data mining, i.e., frequent item sets, association rules, clustering. However, finding regular periodic patterns of events in an infinite data stream gets less attention. Most researches about finding periods use autocorrelation functions to find certain changes in periodic patterns, not period itself. And they usually find periodic patterns in time-series databases, not in data streams. Literally a period means the length or era of time that some phenomenon recur in a certain time interval. However in real applications a data set indeed evolves with tiny differences as time elapses. This kind of a period is called as a pseudo-period. This paper proposes a new scheme called FPMH (Finding Periods using Multiple Hash functions) algorithm to find such a set of pseudo-periods over a data stream based on multiple hash functions. According to the type of pseudo period, this paper categorizes FPMH into three, FPMH-E, FPMH-PC, FPMH-PP. To maximize the performance of the algorithm in the data stream environment and to keep most recent periodic patterns in memory, we applied decay mechanism to FPMH algorithms. FPMH algorithm minimizes the usage of memory as well as processing time with acceptable accuracy.

An Efficient Design Method of Linear-Phase Prototype Lowpass Filter for Near-Perfect Reconstruction Pseudo-QMF Banks (근접 완전재생 Pseudo-QMF 뱅크를 위한 선형위상 프로토타입 저역통과 필터의 효율적인 설계 방법)

  • Jeon, Joon-Hyeon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.3C
    • /
    • pp.271-280
    • /
    • 2008
  • M channel near-perfect-reconstruction(NPR) pseudo-QMF banks are a hybrid of conventional pseudo-QMF design and spectral factorization approach where the analysis and synthesis filters are cosine-modulated versions of the prototype-lowpass filter(p-LPF). However, p-LPF H(z) does not have linear-phase symmetry as well as magnitude-distortion optimization since it is obtained by spectral factorization of $2M^{-th}$ band filter $G(z)=z^{-(N-1)}H(z^{-1})H(z)$. A fair amount of attention, therefore, has been focused on the design of filter banks for reducing only alias-cancellation distortion without reconstructed-amplitude distortion. In this paper, we propose a new method for designing linear-phase p-LPF in NPR pseudo-QMF banks, which is based on Maxflat(maximally flat) FIR filters with closed-form transfer function. In addition, p-LPF H(z) is optimized in this approach so that the 2M-channel overall distortion response represented with $G(z)=H^2(z)$ approximately becomes an unit magnitude response. Through several examples of NPR pseudo-QMF banks, it is shown that the peek ripple of the overall magnitude distortion is less than $3.5{\times}10^{-4}\;({\simeq}-70dB)$ and analysis/synthesis filters have the sharp monotone-stopband attenuation exceeding 100 dB.

A Study on the Hydraulic Excitation Forces Using Transfer Function and Operational Measured Data for the Centrifugal Pump (전달함수와 진동응답 측정에 의한 원심펌프에서의 유체력 특성에 관한 연구)

  • Choi, Bok-Lok;Park, Jin-Moo;Kim, Kwang-Eun
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.8 s.179
    • /
    • pp.1931-1939
    • /
    • 2000
  • Operating excitation forces of the linear vibratory system are normally determined by direct measurement techniques using load cells, strain gauges, etc. But, hydraulic forces of the rotating turbomachinery such as centrifugal pumps are exerted on an impeller due to asymmety of the flow by the interaction between pump impeller and volute. So, investigations of wide range of hydraulic designs and geometric deviations are difficult by direct method. This paper presents a hybrid approach for fourier transformed operational excitation forces, which uses pseudo-inverse matrix of the transfer matrix for the system and the measured vibrational data with standard installed pump. The determination of the transfer function matrix is based on a linear rotor/stationary system and steady state harmonic response in finite element analysis. And, vibrational data is collected in both vertical and horizontal directions at inboard and outboard bearing housings. The results of the process may be enhanced by making acceleration measurements at many more locations than there are forces to be determined.

Optimal Controller for Near-Space Interceptor with Actuator Saturation

  • Fan, Guo-Long;Liang, Xiao-Geng;Hou, Zhen-Qian;Yang, Jun
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.14 no.3
    • /
    • pp.256-263
    • /
    • 2013
  • The saturation of the actuator impairs the response performance of the near space interceptor control system. A control system based on the properties of linear tracking system is designed for this problem. The properties are that the maximum value of the pseudo-Lyapunov function of the linear tracking control system do not present at the initial state but at the steady state, based on which the bounded stability problem is converted into linear tracking problem. The pseudo-Lyapunov function of the linear tracking system contain the input variables; the amplitude and frequency of the input variables affect the stability of the nonlinear control system. Designate expected closed-loop poles area for different input commands and obtain a controller which is function of input variables. The coupling between variables and linear matrices make the control system design problem non-convex. The non-convex problem is converted into a convex LMI according to the Shur complement lemma and iterative algorithm. Finally the simulation shows that the designed optimal control system is quick and accurate; the rationality of the presented design techniques is validated.

Pseudo Image Composition and Sensor Models Analysis of SPOT Satellite Imagery for Inaccessible Area (비접근 지역에 대한 SPOT 위성영상의 Pseudo영상 구성 및 센서모델 분석)

  • 방기인;조우석
    • Korean Journal of Remote Sensing
    • /
    • v.17 no.1
    • /
    • pp.33-44
    • /
    • 2001
  • The paper presents several satellite models and satellite image decomposition methods for inaccessible area where ground control points can hardly acquired in conventional ways. First, 10 different satellite sensor models, which were extended from collinearity condition equations, were developed and then behavior of each sensor model was investigated. Secondly, satellite images were decomposed and also pseudo images were generated. The satellite sensor model extended from collinearity equations was represented by the six exterior orientation parameters in $1^{st}$, $2^{nd}$ and $3^{rd}$ order function of satellite image row. Among them, the rotational angle parameters such as $\omega$(omega) and $\Phi$(phi) correlated highly with positional parameters could be assigned to constant values. For inaccessible area, satellite images were decomposed, which means that two consecutive images were combined as one image, The combined image consists of one satellite image with ground control points and the other without ground control points. In addition, a pseudo image which is an imaginary image, was prepared from one satellite image with ground control points and the other without ground control points. In other words, the pseudo image is an arbitrary image bridging two consecutive images. For the experiments, SPOT satellite images exposed to the similar area in different pass were used. Conclusively, it was found that 10 different satellite sensor models and 5 different decomposed methods delivered different levels of accuracy. Among them, the satellite camera model with 1st order function of image row for positional orientation parameters and rotational angle parameter of kappa, and constant rotational angle parameter omega and phi provided the best 60m maximum error at check point with pseudo images arrangement.

SOME ISOTROPIC CURVES AND REPRESENTATION IN COMPLEX SPACE ℂ3

  • Qian, Jinhua;Kim, Young Ho
    • Bulletin of the Korean Mathematical Society
    • /
    • v.52 no.3
    • /
    • pp.963-975
    • /
    • 2015
  • In this paper, we give a representation formula for an isotropic curve with pseudo arc length parameter and define the structure function of such curves. Using the representation formula and the Frenet formula, the isotropic Bertrand curve and k-type isotropic helices are characterized in the 3-dimensional complex space $\mathbb{C}^3$.

Security Properties of Domain Extenders for Cryptographic Hash Functions

  • Andreeva, Elena;Mennink, Bart;Preneel, Bart
    • Journal of Information Processing Systems
    • /
    • v.6 no.4
    • /
    • pp.453-480
    • /
    • 2010
  • Cryptographic hash functions reduce inputs of arbitrary or very large length to a short string of fixed length. All hash function designs start from a compression function with fixed length inputs. The compression function itself is designed from scratch, or derived from a block cipher or a permutation. The most common procedure to extend the domain of a compression function in order to obtain a hash function is a simple linear iteration; however, some variants use multiple iterations or a tree structure that allows for parallelism. This paper presents a survey of 17 extenders in the literature. It considers the natural question whether these preserve the security properties of the compression function, and more in particular collision resistance, second preimage resistance, preimage resistance and the pseudo-random oracle property.

Optimal Trajectory Design of Descent/Ascent phase for a Lunar Lander With Considerable Sub-Phases (Sub-Phase를 고려한 달착륙선의 Descent/Ascent phase 최적 궤적 생성)

  • Jo, Sung-Jin;Min, Chan-Oh;Lee, Dae-Woo;Cho, Kyeum-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.38 no.12
    • /
    • pp.1184-1194
    • /
    • 2010
  • The descent and ascent phases for a lunar lander are composed of several phases. Accordingly, the constraints and control values adequate for each phase are required in order to generate optimal lander's trajectory. The optimal trajectories for descent and ascent phases are generated by the cost function to minimize fuel consumption & attitude variation rates. In this paper, the optimal control problem to make trajectory uses Gauss pseudo-spectral method which is one of the direct approach method. This problem generates lander's reference trajectory, states and controls.