Neuro‐control of seismically excited steel structure through sensitivity evaluation scheme     

Dong‐Hyawn Kim  In‐Won Lee 《地震工程与结构动力学》2001,30(9):1361-1377

The neuro‐controller training algorithm based on cost function is applied to a multi‐degree‐of‐freedom system; and a sensitivity evaluation algorithm replacing the emulator neural network is proposed. In conventional methods, the emulator neural network is used to evaluate the sensitivity of structural response to the control signal. To use the emulator, it should be trained to predict the dynamic response of the structure. Much of the time is usually spent on training of the emulator. In the proposed algorithm, however, it takes only one sampling time to obtain the sensitivity. Therefore, training time for the emulator is eliminated. As a result, only one neural network is used for the neuro‐control system. In the numerical example, the three‐storey building structure with linear and non‐linear stiffness is controlled by the trained neural network. The actuator dynamics and control time delay are considered in the simulation. Numerical examples show that the proposed control algorithm is valid in structural control. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

A method for computing the coefficients in the product-sum formula of associated Legendre functions     

Cheinway Hwang 《Journal of Geodesy》1995,70(1-2):110-116

The product of two associated Legendre functions can be represented by a finite series in associated Legendre functions with unique coefficients. In this study a method is proposed to compute the coefficients in this product-sum formula. The method is of recursive nature and is based on the straightforward polynomial form of the associated Legendre function's factor. The method is verified through the computation of integrals of products of two associated Legendre functions over a given interval and the computation of integrals of products of two Legendre polynomials over [0,1]. These coefficients are basically constant and can be used in any future related applications. A table containing the coefficients up to degree 5 is given for ready reference.  相似文献   

Horizontal and vertical distribution of PCBs and chlorinated pesticides in sediments from Masan Bay,Korea   总被引：1，自引：0，他引：1  

Hong SH  Yim UH  Shim WJ  Oh JR  Lee IS 《Marine pollution bulletin》2003,46(2):244-253

Horizontal and vertical distributions of organochlorine compounds (OCs) were determined in sediments from Masan Bay. The concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), HCB, hexachlorocyclohexanes (HCHs) and chlordane related compounds (CHLs) in sediments were in the range of 1.24-41.4, 0.28-89.2, 0.02-0.59, nd-1.03, and nd-2.56 ng/g, respectively. The spatial distribution of OCs showed a negative gradient from the inner of the bay to outer part of the bay, indicating that the source of OCs was probably located inside the bay. Compositional pattern of PCB congeners showed a relatively high concentration of high-chlorinated congeners in the inner part of the bay and a relatively low concentration of low-chlorinated congeners in the outer part. In sediment core from Masan Bay maximum concentrations of PCBs and DDTs are observed in the subsurface samples and correspond to an age of early 1980s and late 1960s. The concentration profiles of PCBs and DDTs in sediments of Masan Bay appear to correspond to use of PCBs and DDTs in Korea.  相似文献   

一种多前缘多阈值的波形重构算法   总被引：5，自引：0，他引：5       下载免费PDF全文

常晓涛  李建成  郭金运  黄金维 《地球物理学报》2006,49(6):1629-1634

为了改善近海测高精度,本文对近海测高波形的特征进行了研究,并在现有算法的基础上提出基于波前缘识别算法的多前缘多阈值波形重构方法.然后将该方法用于中国近海的卫星测高波形数据的处理,得到精度与分辨率更好的海面高数据.作为验证,将此海面高数据换算为重力异常并与船测重力进行比较,结果显示该方法可以明显提高卫星测高精度.  相似文献   

Climate Warming and Water Management Adaptation for California   总被引：1，自引：3，他引：1  

Stacy K. Tanaka  Tingju Zhu  Jay R. Lund  Richard E. Howitt  Marion W. Jenkins  Manuel A. Pulido  Mélanie Tauber  Randall S. Ritzema  Inês C. Ferreira 《Climatic change》2006,76(3-4):361-387

The ability of California's water supply system to adapt to long-term climatic and demographic changes is examined. Two climate warming and a historical climate scenario are examined with population and land use estimates for the year 2100 using a statewide economic-engineering optimization model of water supply management. Methodologically, the results of this analysis indicate that for long-term climate change studies of complex systems, there is considerable value in including other major changes expected during a long-term time-frame (such as population changes), allowing the system to adapt to changes in conditions (a common feature of human societies), and representing the system in sufficient hydrologic and operational detail and breadth to allow significant adaptation. While the policy results of this study are preliminary, they point to a considerable engineering and economic ability of complex, diverse, and inter-tied systems to adapt to significant changes in climate and population. More specifically, California's water supply system appears physically capable of adapting to significant changes in climate and population, albeit at a significant cost. Such adaptation would entail large changes in the operation of California's large groundwater storage capacity, significant transfers of water among water users, and some adoption of new technologies.  相似文献   

Irrigated area determination: a case study in the Province of San Juan,Argentina     

Graciela Salinas de Salmuni  Inés Velasco  Mirta Fresina  Alberto L. Flores 《GeoJournal》2007,70(4):273-279

Much of the central-western region of Argentina, where San Juan Province is located, experiences arid to semi-arid climatic conditions with low average annual rainfall accompanied by substantial evapotranspiration. Consequently, a viable crop industry depends to a large extent upon irrigation from major river systems. Increasing demand for water in the lower basin of the San Juan River is emphasizing the need for more accurate estimates of water used for irrigation. Since the water demand for a particular crop is very closely related to crop area, monitoring the area of crop under irrigation is considered a proxy for the amount of water used. Landsat 5 imagery for the growing season, field data and aerial photographs were used to evaluate crop area.  相似文献   

Fast integration of low orbiter's trajectory perturbed by the earth's non-sphericity     

C. Hwang  M.-J. Lin 《Journal of Geodesy》1998,72(10):578-585

A fast algorithm is proposed to integrate the trajectory of a low obiter perturbed by the earth's non-sphericity. The algorithm uses a separation degree to define the low-degree and the high-degree acceleration components, the former computed rigorously, and the latter interpolated from gridded accelerations. An FFT method is used to grid the accelerations. An optimal grid type for the algorithm depends on the trajectory's permissible error, speed, and memory capacity. Using the non-spherical accelerations computed from EGM96 to harmonic degree 360, orbit integrations were performed for a low orbiter at an altitude of 170 km. For a separation degree of 50, the new algorithm, together with the predict-pseudo correct method, speeds up the integration by 145 times compared to the conventional algorithm while keeping the errors in position and velocity below 10⁻⁴ m and 10⁻⁷ m/s for a 3-day arc. Received: 28 July 1997 / Accepted: 1 April 1998  相似文献   

Reconciling Discrepancies Between Airborne and Buoy-Based Measurements of Wind Stress Over Mixed Seas     

Héctor García-Nava  Francisco J. Ocampo-Torres  Paul A. Hwang 《Boundary-Layer Meteorology》2015,155(3):515-526

  相似文献   

The Fresnel space imager as a disk evolution watcher     

Ana In��s G��mez de Castro 《Experimental Astronomy》2011,30(2-3):205-216

The Fresnel Diffractive Imaging Arrays form high resolution images by diffraction with low radiometric efficiencies. They are extremely good devices to make high resolution imaging and integral field spectroscopy of bright sources. Thirty meter arrays will provide a spatial resolution of 0.8 mas at Lyman-?? that will open a completely new field of research: the study of matter distribution around disks and their gravitational drives. In this contribution, the potentials of the 3.6 m precursors (or probes) for astrophysical disks and jets research, are described. Main emphasis is made on young planetary disks.  相似文献   

Relationship of ground level enhancements with solar,interplanetary and geophysical parameters     

K. A. Firoz  J. Hwang  I. Dorotovič  T. Pintér  Subhash C. Kaushik 《Astrophysics and Space Science》2011,331(2):469-484

Cosmic rays registered by Neutron Monitor on the surface of the Earth are believed to originate from outer space, and sometimes also from the exotic objects of the Sun. Whilst the intensities of the cosmic rays are observed to be enhanced with sudden, sharp and short-lived increases, they are termed as ground level enhancements (GLEs). They are the occurrences in solar cosmic ray intensity variations on short-term basis, so different solar factors erupted from the Sun can be responsible for causing them. In this context, an attempt has been made to determine quantitative relationships of the GLEs having peak increase >5% with simultaneous solar, interplanetary and geophysical factors from 1997 through 2006, thereby searching the responsible factors which seem to cause the enhancements. Results suggest that GLE peaks might be caused by solar energetic particle fluxes and solar flares. The proton fluxes which seemed to cause GLE peaks were also supported by their corresponding fluences. For most of the flares, the time integrated rising portion of the flare emission refers to the strong portion of X-ray fluxes which might be the concern to GLE peak. On an average, GLE peak associated X-ray flux (0.71×10⁻⁴ w/m²) is much stronger than GLE background associated X-ray flux (0.11×10⁻⁶ w/m²). It gives a general consent that the GLE peak is presumably caused by the solar flare. Coronal mass ejection alone does not seem to cause GLE. Coronal mass ejection presumably causes geomagnetic disturbances characterized by geomagnetic indices and polarities of interplanetary magnetic fields.  相似文献