Control design for seismically excited buildings: sensor and actuator reliability     

T. R. Alt  F. Jabbari  J. N. Yang 《地震工程与结构动力学》2000,29(2):241-257

In this paper we present control design methods that provide desirable levels of performance and simultaneously account for actuator and sensor reliability (or malfunction) for buildings under seismic excitations. Performance is defined in terms of the disturbance attenuation (i.e. L₂ gain) from the disturbances to the controlled outputs of the system. The reliability of actuators and sensors refers to the deviation of actual control forces or actual sensor measurements from their ideal levels. Simulation results for a six‐storey building are used to demonstrate the effectiveness of the control analysis and design method presented. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Stability analysis of multi-directional anchored rock slope subjected to surcharge and seismic loads     

Sanjay Kumar Shukla  Md. Monir Hossain 《Soil Dynamics and Earthquake Engineering》2011,31(5-6):841-844

More than one set of anchors with different orientations can be an economical solution to completely stabilize the rock slope. In this note, a general analytical expression for the factor of safety of a multi-directional anchored rock slope (MDARS) against plane failure is derived, incorporating most of the practically occurring destabilizing forces under surcharge and seismic loading conditions. Several special cases of this expression are found to be similar to those reported in the literature. A graphical presentation shows that for any specific inclination of one set of anchors to the normal at failure plane, the variation in the inclination of the second set of anchors to the normal at failure plane, when greater than approximately 60°, does not cause a significant change in the factor of safety of the MDARS.  相似文献   

Validation of a TRMM-based global Flood Detection System in Bangladesh     

Caitlin Balthrop Moffitt  Faisal Hossain  Robert F. Adler  Koray K. Yilmaz  Harold F. Pierce 《International Journal of Applied Earth Observation and Geoinformation》2011

Although the TRMM-based Flood Detection System (FDS) has been in operation in near real-time since 2006, the flood ‘detection’ capability has been validated mostly against qualitative reports in news papers and other types of media. In this study, a more quantitative validation of the FDS over Bangladesh against in situ measurements is presented. Using measured stream flow and rainfall data, the study analyzed the flood detection capability from space for three very distinct river systems in Bangladesh: (1) Ganges– a snowmelt-fed river regulated by upstream India, (2) Brahmaputra – a snow-fed river that is braided, and (3) Meghna – a rain-fed and relatively flashier river. The quantitative assessment showed that the effectiveness of the TRMM-based FDS can vary as a function of season and drainage basin characteristics. Overall, the study showed that the TRMM-based FDS has great potential for flood prone countries like Bangladesh that are faced with tremendous hurdles in transboundary flood management. The system had a high probability of detection overall, but produced increased false alarms during the monsoon period and in regulated basins (Ganges), undermining the credibility of the FDS flood warnings for these situations. For this reason, FDS users are cautioned to verify FDS estimates during the monsoon period and for regulated rivers before implementing flood management practices. Planned improvements by FDS developers involving physically-based hydrologic modeling should transform the system into a more accurate tool for near real-time decision making on flood management for ungauged river basins of the world.  相似文献   

A comparative study of the ATC-40 recommended and numerically derived M-(ψ) relationship     

Sifat Sharmeen Muin  Tahsin Reza Hossain 《地震工程与工程振动(英文版)》2011,10(4)

Nonlinear static analysis procedures are key tools in evaluating the performance of existing buildings and verifying the design of seismic retrofits in seismically active regions.In this procedure,nonlinear force-displacement or moment-curvature (M-(4)) behavior needs to be defined.In the ATC-40 document,values of M-~ have been proposed to model elements in a nonlinear procedure.However,these values need to be investigated to determine if they are representative of actual values.In this paper,an attempt has been made to numerically derive M-（4） curves to simulate actual performance.Then,these curves are compared with the ATC-40 recommended curves with respect to various parameters.The study indicated that ATC-40 suggested values are conservative in nature in most situations.  相似文献   

Statistical characterization of arsenic contamination in shallow tube wells of western Bangladesh     

Faisal Hossain  Amvrossios C. Bagtzoglou  Nurun Nahar  M. Delawer Hossain 《水文研究》2006,20(7):1497-1510

A regional assessment of the arsenic (As) contamination scenario in shallow tube wells (depth < 150 m) of western Bangladesh is presented. Comparisons are made in light of bulk geological differences (Pleistocene versus Holocene deposits/northwest versus southwest) and As measurement protocols (field kit (FK) versus atomic absorption spectroscopy (AAS)). Our As database comprised the following: (1) the nationwide As survey completed in 1999 by the British Geological Survey in collaboration with the Department of Public Health Engineering (DPHE); and (2) a regional As survey conducted in southwest Bangladesh by the Japan International Cooperation Agency in collaboration with DPHE in 2002. First, we characterize the error structure of the semi‐quantitative FK As measurements using collocated AAS As measurements as reference from a set of 307 wells located in southwest Bangladesh. The depth distribution of As is identified using a very dense cluster of 2963 wells over a 560 km² domain. The probability of the FK method for successful detection of a well sample as unsafe (safe) was found to be 96·9% (34·1%) and 95·2% (80·3%) for the World Health Organization (WHO) and Bangladesh safe limits, respectively. Similarly, the probability of false alarms and false hopes for WHO (Bangladesh) safe limits were found to be 3·1% (4·8%) and 87·5% (19·7%), respectively. The depth at which the highest fraction of wells exceeding a given safe limit occurred could still be inferred correctly by FK measurements. A simple bias adjustment procedure on FK As data did not result in a more accurate characterization of depth distribution of As. This indicated that simple error statistics are inadequate for advancing the utility of FKs; rather, an understanding of the complex and multidimensional error structure is required. Regional anisotropy in the spatial dependence of As for the northwest was found to be stronger than the southwest. The correlation length for As concentration in the east–west direction of northwest Bangladesh (i.e. across major river floodplains) was found to be almost twice (158·80 km) that of the north–south direction (along the major axis of Pleistocene deposits) (78·21 km). For the southwest region, the ratio of east–west to north–south correlation lengths ranged from 1·40 to 1·51. For the northwest region, because it is well known to have the lowest concentrations of As countrywide, knowledge of this anisotropy appears to suggest the need for drilling twice as many remediation deep wells in the proximity of an unsafe shallow well in the north–south direction than in the east–west direction. Findings from this study are potentially useful in setting priority areas for emergency testing, distributing remediation resources equitably and formulating a regional water resources strategy for western Bangladesh. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Foundation design considerations for a pile supported critical facility     

Thomas W. Houston  Carl J. Costantino  Quazi Hossain  N. Earl Stone 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1169-1174

A large reinforced concrete structure supported on piles extending to bedrock is evaluated using a seismic soil–structure interaction analysis. The physical structure, the supporting pile system, analysis model and analytical methodology used are described. Important considerations in the design of the foundation pile system using the seismic analysis loadings and deformations are discussed.  相似文献   

Planar Gardner solitons and double layers in dusty electronegative plasmas with kappa distributed electrons     

T. Akhter  M. M. Hossain  A. A. Mamun 《Astrophysics and Space Science》2013,345(2):283-290

A theoretical investigation has been made on the Dust ion-acoustic (DIA) Gardner solitons (GSs) and double layers (DLs) in electronegative plasma consisting of inertial positive and negative ions, super-thermal (kappa distributed) electrons, and negatively charged static dust. The standard reductive perturbation method is employed to derive the Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and standard Gardner equations, which admits solitary waves (SWs) and DLs solutions. It have been found that GSs and DLs exist for α around its critical value α _c , where α _c is the value of α corresponding to the vanishing of the nonlinear coefficient of the K-dV equation. The parametric regimes for the existence of both the positive as well as negative SWs and negative DLs are obtained. The basic features of DIA SWs and DLs are analyzed and it has been found that the polarity, speed, height, thickness of such DIA SWs and DLs structures, are significantly modified due to the presence of two types of ions and spectral index (κ) of super-thermal electrons. It has also been found that the characteristics of DIA GSs and DLs, are different from that of the K-dV solitons and mK-dV solitons. The relevance of our results to different interstellar space plasma situations are discussed.  相似文献   

Hot plasma waves in Veselago medium around Reissner-Nordström black hole     

M. Hossain Ali  M. Ashrafuzzaman Khan 《Astrophysics and Space Science》2013,348(1):163-178

We investigate the general relativistic magnetohydronadynamic (GRMHD) equations for hot plasmas in a Veselago medium around the Reissner-Nordström (RN) black hole. Using the 3+1 formalisms of spacetime, we write the GRMHD equations and perturb them linearly. These are then Fourier analyzed for the magnetized and nonmagnetized plasmas in rotating and nonrotating backgrounds. We derive dispersion relations and analyze the wave properties by the graphs of wave vector, refractive index and change in refractive. The results confirm the presence of Veselago medium for rotating magnetized/nonmagnetized and nonrotating nonmagnetized plasmas.  相似文献   

Application of the honey-bees mating programming (HBMP) algorithm to sediment concentration modelling     

Hassan Ebrahimi  Ebrahim Jabbari  Mostafa Ghasemi 《水文科学杂志》2013,58(10):1853-1864

Abstract

The honey-bees mating programming (HBMP) algorithm is introduced as a novel tool for predicting suspended sediment concentration for the Mad River catchment near Arcata, USA. The paper also applies gene expression programming (GEP) as a comparison and shows that these two approaches can the produce transparent, nonlinear relationships between the independent and dependent variables. Some modifications have been made to the HBMP algorithm to improve its capability and efficiency. The results achieved from this method and GEP are compared with two different sediment rating curves based on regression techniques. The findings show that the results from both the HBMP and GEP methods are promising and outperform the results obtained from the sediment rating curves.