Seismic demand of plan-asymmetric structures: a revisit

In view of the recognition of the importance of the interdependent behavior of strength and stiffness of walltype structural elements,the seismic demand of plan-asymmetric systems is revisited.Useful strength distribution strategies,i.e.,’Center of Strength-Center of Mass(CV-CM) coinciding’ and ’Balanced Center of Strength-Center of Resistance(CVCR)’ are adopted.Design charts for the seismic demand of classical uni-directionally and bi-directionally asymmetric systems are developed in a simple unified format.A conceptual framework is also outlined to conveniently apply the design charts.Illustrations are included to explain the use of the current recommendations in practical design.The study also highlights the relative performance of ’CV-CM coinciding’ and ’Balanced CV-CR’ criteria.     

Nonthermal production of baryon and dark matter

We study nonthermal production of baryon and dark matter. If we extend the MSSM by introducing some singlet chiral superfields so as to enlarge the conserved global symmetry, the abundance of the baryon and the dark matter in the universe may be explained as the charge asymmetry of that symmetry. In such a case, the baryon energy density and the dark matter energy density in the present universe can be correlated each other and take the similar order values naturally.     

Hemispheric asymmetry of sunspot area in solar cycle 23 and rising phase of solar cycle 24: Comparison of three data sets

Analysis of long-term solar data from different observatories is required to compare and confirm the various level of solar activity in depth. In this paper, we study the north–south asymmetry of monthly mean sunspot area distribution during the cycle-23 and rising phase of cycle-24 using the data from Kodaikanal Observatory (KO), Michelson Doppler Imager (MDI) and Solar Optical Observing Network (SOON). Our analysis confirmed the double peak behavior of solar cycle-23 and the dominance of southern hemisphere in all the sunspot area data obtained from three different resources. The analysis also showed that there is a 5–6 months time delay in the activity levels of two hemispheres. Furthermore, the wavelet analysis carried on the same data sets showed several known periodicities (e.g., 170–180 days, 2.1 year) in the north–south difference of sunspot area data. The temporal occurrence of these periods is also the same in all the three data sets. These results could help in understanding the underlying mechanism of north–south asymmetry of solar activity.     

基于地貌计量指标分析的钱塘江流域地貌演化特征

地貌过程的定量化表达已成为构造地貌学研究中的一种趋势。基于ASTER GDEM数据,运用GIS空间分析技术,本文获得了钱塘江流域87个子流域的地貌参数,包括面积-高程积分（HI）、面积-高程积分曲线（HC）、坡度、流域不对称度（AF）、流域盆地形状指数（Bs）等。进一步结合流域内地层特征与自然地理背景,探讨了钱塘江流域地貌演化阶段以及流域内主要断裂（江山-绍兴断裂、球川-萧山断裂和马金-乌镇断裂）的相对活动性。结果表明：1）HI值在小尺度范围内主要反映岩性差异,在大的空间尺度下则可能主要与构造活动性有关;2）相对于HI指数,AF和Bs更有助于揭示构造活动性的空间差异;3）基于AF、Bs、坡度、HI等的分析,认为江山-绍兴断裂和球川-萧山断裂北段的活动性要弱于南段,而马金-乌镇断裂南、北段构造活动性差异不显著;4）多种地貌计量指标的分析结果（HI=0.217、|AF-50|=4.27、Bs=0.77）均显示钱塘江流域处于地貌演化的老年阶段。

     

天津港水域围垦条件下的水动力变化分析

本研究旨在讨论天津滨海新区的围垦对其附近水域水动力和悬沙输运所造成的影响,并进行定量评估。在天津港南部、北部海域分别选取4个站位进行了全潮水文观测,获取了流速剖面、悬沙浓度剖面数据,并据此计算了底切应力、潮不对称性以及余流。结果表明,底部悬沙浓度与流速、底切应力存在相位一致性,绝大部分站位的沉积物都呈现向岸净输运的趋势,悬沙通量分解显示潮汐捕捉项是该区域悬沙输运的主要贡献项;围垦愈增的2009～2015年,天津港北部潮不对称性增强,向陆的单宽悬沙输运率由20.15 g/(m·s)变至24.92 g/(m·s),而南部海域潮不对称性减弱,向陆的单宽悬沙输运率从37.75 g/(m·s)减小至6.37 g/(m·s)。综上,持续地围垦可能导致天津港附近海域的水动力条件改变,推测北部潮滩淤涨可能加快,而南部淤涨速率减小。     

Genetic and morphological description of Eucalanus spinifer T. Scott, 1894 (Calanoida: Eucalanidae), a circumglobal sister species of the copepod E. hyalinus s.s. (Claus, 1866)

A distinct genetic form of the eucalanid calanoid copepod Eucalanus hyalinus s.l. was identified in subtropical and temperate waters of the Pacific, Atlantic, and Indian Oceans. Results from mitochondrial (16S rRNA, COI) and nuclear (ITS2) genetic markers suggest that the two E. hyalinus forms are reproductively isolated. Eucalanus spinifer T. Scott is taken out of synonymy with E. hyalinus and is applied to the smaller of the two genetic forms, increasing the number of species in the genus Eucalanus to a total of six. Adult females of the sister species E. hyalinus s.s. and E. spinifer can be distinguished morphologically by the shape of the anterior portion of the head in lateral and ventral views, asymmetry in the length of antennule segments 22 and 23, length ratios of 22/5 and 23/5 of the longer of the antennules, the length of the caudal rami, and total body size, as measured by total length or prosome length. We illustrate and describe both adult females and males of E. spinifer, and discuss aspects of sexual dimorphism. The sister species are sympatric throughout much of their circumglobal biogeographic distributions, but appear to have centers of abundance in slightly different water mass types.     

大糙率珊瑚礁附近规则波非线性特征实验研究

通过波浪水槽实验对大糙率礁面存在下珊瑚礁海岸附近规则波非线性特征参数(偏度、不对称度和厄塞尔数)的变化规律进行了研究。实验采用圆柱体阵列来模拟礁面的粗糙度,测试了一系列规则波工况。结果表明:偏度、不对称度和厄塞尔数的幅值分别在珊瑚礁破碎带结束位置、破碎带内和破碎带开始位置达到最大。3个参数的幅值均随着入射波波高的增大而增大;偏度值随着波浪周期的增大而减小,不对称度幅值和厄塞尔数随着周期的增大而增大;偏度值随着礁坪水深的增大而增大,不对称度幅值和厄塞尔数随着礁坪水深的增大而减小。深水厄塞尔数可以用来描述礁坪上波浪非线性参数的变化,最后给出了用其预测礁坪上3个非线性特征参数的经验关系式。     

Evidence for spatially variable friction from tidal amplification and asymmetry in the Pertuis Breton (France)

The semi-diurnal tides are amplified and distorted as they propagate into the Pertuis Breton, a semi-enclosed shallow basin in the north-eastern part of Bay of Biscay, in France. This paper investigates the influence of bottom friction on amplification and phase lag of the tidal constituent M2 and its overtide M4 in the Pertuis Breton. A fine resolution two-dimensional (2D) numerical model is implemented to simulate tidal propagation. The model solves the depth-averaged shallow-water equations on a finite element grid using the TELEMAC 2D software. A two-zone parameterisation of friction coefficient is introduced to evaluate the impact of smooth mud flats on the tidal asymmetry and amplification in the Pertuis. Fitting the model to observed amplitudes and phases of M2 and M4 evaluates the decrease of Chezy friction coefficient from the mud flats to the rest of the Pertuis as 100:60. This conclusion is supported by the direct estimation based on morphology and composition of sea bed in the Pertuis Breton.     

热带太平洋ENSO振荡的空间对称和非对称成分

用SSA（奇异谱分析）识别出ENSO振荡的前两个周期成分，在此基础上对NCEP／NCAR资料以及风应力资料采用合成场的空间对称和非对称方法，分析和比较物理量场对Nino3、4指数的两个主要周期成分的线性和非线性响应。结果表明：空间场的线性响应A^（1）决定了两个主周期成分与ENSO的位相关系；非线性响应A^（2）决定空间不对称性。A^（1）和A^（2）的相互作用对于空间场的影响分成4种情况：情况1（A^（1）〉0，A^（2）〉0）、2（A^（1）〉0，A^（2）〈0）使得空间场振荡与ENSO同位相，情况3（A^（1）〈0，A^（2）〈0）、4（A^（1）〈0，A^（2）〉0）则反之；情况1、3使得在ENSO暖位相时合成场的振荡强，而情况2、4反之。空间不对称性最大的地方与线性响应最大的地方总是比较接近：SLP位于南太平洋，作用的情况分别是1和4；SSTA位于赤道东太平洋；τx位于赤道中西太平洋，属于情况1；τy位于中太平洋赤道北侧和南侧，由北向南分别是情况3和1。这种特征使得在ENSO暖位相时，合成场中主要距平区的振荡强度偏强，更有利于形成ENSO暖事件。这与最近38a来ENSO暖事件普遍偏强的现象吻合。     

On the structural age of the Rhoscolyn antiform,Anglesey, North Wales

In the Rhoscolyn area of Anglesey, the late Precambrian interbedded psammites and pelites of the Monian Supergroup are folded into a kilometre‐scale antiform, plunging about 25°NE and with an axial surface dipping about 40°NW. Numerous folds of up to a few tens of metres in wavelength are present on both limbs of this antiform. These smaller‐scale folds also plunge about 25°NE but clearly belong to two separate episodes of folding, and it has become a matter of longstanding controversy as to whether the larger antiform belongs to the first or second of these episodes. Close examination of the cleavage/bedding asymmetries from all the lithologies, however, shows that the large antiform is a second‐generation structure, and that on the gently dipping northwest limb, the sense of cleavage/bedding asymmetry of the earlier cleavage in the psammitic units has been almost uniformly and homogeneously reversed (so that it appears to be axial planar to the antiform), while in the pelitic units the sense of cleavage/bedding asymmetry of the earlier cleavage has been preserved. Many of the small‐scale complexities of the observed cleavage/bedding relationships may be explained by appealing to differences in the timing of the formation of buckling instabilities relative to this reorientation of the early cleavage in the psammites during the second deformation. A first‐order analysis of the finite strains from around the large‐scale antiform shows that the orientation of the first cleavage prior to the second deformation was steeply dipping to the southeast. The second deformation correlates with the southeast‐verging Caledonian deformation affecting the Monian and Ordovician units elsewhere in northwest Anglesey, while the northwest‐verging first deformation event, which is not present in the Ordovician rocks, must have occurred before they were deposited. Copyright © 2004 John Wiley & Sons, Ltd.