合理确定梁端塑性铰弯矩值及改进钢框架梁连接设计

多次强震震害表明,梁破坏时梁端截面并未能形成理想塑性铰,而是在梁柱连接处发生脆性破坏。提出了改进钢框架梁连接设计的具体作法,即局部加大梁端焊缝截面的同时,在梁端一定距离处又适当削弱梁翼缘尺寸,合理确定梁端塑性铰弯矩,按梁两端出现同向塑性铰求出钢框架梁柱连接、梁的拼接处的内力(M、V)作为多遇地震作用下的调整内力设计值,改进梁柱连接、梁拼接的设计,供工程设计和修订相应规范作参考。     

一种利用广义点和物方补偿纠正建筑影像的算法

针对双灭点条件下纠正大倾角近景影像算法的不足,提出了基于灭点理论、空间直线几何补偿联合广义点(直线)摄影测量光束法平差的建筑物影像自动纠正算法。实验结果表明,改进算法具有一定效果。     

采用灰度分割的自适应矩匹配条带噪声去除方法

针对国产卫星全色影像中的随机条带噪声现象,提出了一种采用灰度分割的自适应矩匹配条带噪声去除方法。该方法首先将不同反射特性的地物按照灰度差异进行分割处理,然后对每一个分割区域分别采用标准矩匹配进行处理,从而抑制标准矩匹配处理过程中造成的灰度畸变。选取资源1号02C-HR光学影像进行实验,结果表明,与现有的去噪方法相比,所得图像质量有较大提升。     

Dipolar magnetic moment of the bodies of the solar system and the Hot Jupiters

Context

The planets magnetic field has been explained based on the dynamo theory, which presents as many difficulties in mathematical terms as well as in predictions. It proves to be extremely difficult to calculate the dipolar magnetic moment of the extrasolar planets using the dynamo theory.

Objective

The aim is to find an empirical relationship (justifying using first principles) between the planetary magnetic moment, the mass of the planet, its rotation period and the electrical conductivity of its most conductive layer. Then this is applied to Hot Jupiters.

Method

Using all the magnetic planetary bodies of the solar system and tracing a graph of the dipolar magnetic moment versus body mass parameter, the rotation period and electrical conductivity of the internal conductive layer is obtained. An empirical, functional relation was constructed, which was adjusted to a power law curve in order to fit the data. Once this empirical relation has been defined, it is theoretically justified and applied to the calculation of the dipolar magnetic moment of the extra solar planets known as Hot Jupiters.

Results

Almost all data calculated is interpolated, bestowing confidence in terms of their validity. The value for the dipolar magnetic moment, obtained for the exoplanet Osiris (HD209458b), helps understand the way in which the atmosphere of a planet with an intense magnetic field can be eroded by stellar wind. The relationship observed also helps understand why Venus and Mars do not present any magnetic field.     

Density distribution functions and correlations of earthquake parameters

The statistical analysis of the source parameters of 9 earthquake sets of different types (aftershocks, scattered events, swarms) and of different seismic regions shows that the density distribution function (ddf) of the linear dimension l of a fault is represented by a negative power law, as well as the ddf of the static stress drop σ and of the scalar seismic moment M_o. It is then suggested, and tentatively verified, that also the ddf of the root mean square ground acceleration, defined as a function of l and σ, may be represented by a negative power law and that, at least in the cases examined, it scales like the ddf of σ. It is seen that the variability of the static stress drop is significant from one region to another, as is well known, but it seems remarkable also in the same seismic region (in particular in California, σ varies by several orders of magnitude) and in the different sets of events of a given region (as observed again for California). It is hypothesized that a correlation, although weak, between the stress drop and the linear dimension of a fault exists and the analyses seem not to contradict that σ may be a decreasing function of l. Finally, it is suggested that the seismicity of a region may be represented two-dimensionally as a function of the ddf of the stress drop and of the linear dimension of a fault instead of the classic b and b_o values.     

Modified Weibull-derived spectrum for deep water significant wave height estimation

The modified Weibull spectrum is utilized to calculate the zeroth spectral moment (m_o) using Monte Carlo integration methods. Then significant wave height (H_s) is calculated using the formula This is validated with observed buoy data and numerical wave model (WAM) predicted significant wave heights. The Weibull parameters have been calculated using energy densities from observed spectra recorded by DS5 buoy (13.80° N, 82.52° E, depth 3355.48 m) by the method of maximum likelihood (MLE).The relative root mean square error (RRMS) and relative bias error criteria show that modified Weibull spectrum estimated significant wave heights are better than those predicted by WAM model. The monthly averaged observed wave power spectra for the year 2005 recorded by deep water buoy DS5 is considered in this work. The spectra exhibit bimodal sea states for several months of the year.     

Expected probability weighted moment estimator for censored flood data

Two well-known methods for estimating statistical distributions in hydrology are the Method of Moments (MOMs) and the method of probability weighted moments (PWM). This paper is concerned with the case where a part of the sample is censored. One situation where this might occur is when systematic data (e.g. from gauges) are combined with historical data, since the latter are often only reported if they exceed a high threshold. For this problem, three previously derived estimators are the “B17B” estimator, which is a direct modification of MOM to allow for partial censoring; the “partial PWM estimator”, which similarly modifies PWM; and the “expected moments algorithm” estimator, which improves on B17B by replacing a sample adjustment of the censored-data moments with a population adjustment. The present paper proposes a similar modification to the PWM estimator, resulting in the “expected probability weighted moments (EPWM)” estimator. Simulation comparisons of these four estimators and also the maximum likelihood estimator show that the EPWM method is at least competitive with the other four and in many cases the best of the five estimators.     

大弯矩混凝土电杆的设计计算与选择

随着地区经济的发展和人民生活水平的提高,电网用电负荷大幅增加。根据本地区当前用电量及配网发展规划的需要,新建架空主干线路一般都选用大截面导线,多采用双回路架设,这就对混凝土电杆的强度提出了更高的要求。本文通过典型计算详细介绍了直线电杆的水平受力情况及大弯矩混凝土电杆的设计选择,并对其进行归纳,可供相关设计人员的参考。     

抗震变形验算中钢筋混凝土梁柱截面特性的计算

罕遇地震作用下结构的抗震变形验算需要利用钢筋混凝土梁柱构件的三折线模型，国内外对该模型的主要参数Mc,My,α有不同的计算方法。本文介绍了几种典型的方法，并通过数值算例进行了对比计算。其中基于近似理论分析的方法与基于实验统计的经验方法之间的差异不超过20％－30％，可用于工程实践。本文还比较了各种方法的适用性。     

由宽频带辐射能量目录和地震矩目录给出的视应力及其地震学意义

对NEIC宽频带地震辐射能量目录和哈佛矩心矩张量（CMT）目录的比较，给出了关于视应力的一些可能是有意义的结果，尽管目前的结果误差仍很大，可靠性也是有限的，但这种比较所提供的线索却颇值得注意，视应力的计算给出关于地震断层面上非线性动摩擦函数的线索，能量／地震矩之比随地震大小的变化表明，在BK模型框架下，对于走滑型地城,依赖于滑动速度的摩擦似乎占主要地位，而对于非走滑型地震，依赖于位移的摩擦似乎占主要地位，主震和余震的能量／地震矩之比的比较表明，对于走滑型地震，余震的视应力平均地说来低于主震的视应力，而对于非直滑型地震，余震的视应力即有高于主震的也有低于主震的，这对于障碍体和凹凸模式的讨论及模型中地震破裂停止条件的设置可能具有一定的参考意义。