Effect of Irregular Seabed on Seismic Motions

Several studies indicate that marine seismic activity is vast. Actually, about 90% of all natural earthquakes have epicenters in o_shore areas and may cause damage to subsea and floating structures. In this numerical study the indirect boundary element method is used to analyze the influence that some parameters, involved in this kind of problems, have on the dynamic response of marine waters under the incidence of theoretical seismic events. According with the results, the seismic amplifications depend on the seabed configuration and produce displacements which can be a serious concern.     

IBEM for Impedance Functions of an Embedded Strip Foundation in a Multi-Layered Transversely Isotropic Half-Space

An indirect boundary element method (IBEM) is developed to study the dynamic impedance functions (stiffness coefficients) of a rigid strip foundation embedded in a multi-layered viscoelastic transversely isotropic (TI) half-space. The proposed IBEM using half-space Green’s functions of distributed loads as fundamental solutions have the merits of fictitious loads being directly applied on the real boundaries without the problem of singularity and of the discretization effort restricted to local boundaries. In addition, the accuracy of the proposed method is not affected by the thickness of the discrete TI layers, as the exact dynamic stiffness matrix is employed. The presented algorithm is verified via comparisons with published results for the isotropic medium. By taking a rigid strip foundation embedded in a homogeneous half-space, a single-layered half-space, and a multi-layered half-space as examples, the effects of material anisotropy, frequency of excitation, and soil layer on the impedance functions are studied in detail. Numerical results show that impedance functions for the TI medium can be significantly different from those of the isotropic case. The variation of TI parameters alters the dynamic characteristics of the TI layered site, which in turn alters the dynamic interaction between the soil and foundation. In addition, the soil sedimentary sequence also has a remarkable influence on the impedance functions.     

Evaluation of 2D Seismic Site Response due to Hill-Cavity Interaction Using Boundary Element Technique

This paper deals with the evaluation of two-dimensional site-effects due to the seismic interaction between hills with various configurations and underground cavities. The time-domain boundary element method is used to evaluate the site-effects of hill-cavity interaction subjected to vertically propagating in-plane SV and P waves. The presence of an underground cavity and the hill topography are expected to induce significant effects on the surface ground motion. To further examine the contribution of the amplification ratio of the hill-cavity system, a fairly simple approach, which can compute the response spectra of the hill’s surface motion above a cavity based on the real input motions, is also used to input motions.     

SYSTEM IDENTIFICATION OF FEI-TSUI ARCH DAM FROM FORCED VIBRATION AND SEISMIC RESPONSE DATA

This paper presents the experimental investigation of the Fei-Tsui arch dam using the forced vibration test and its seismic response data. A forced vibration test was conducted on Fei-Tsui dam, this study presents the identified dynamic properties of the dam from these test data. For the identification of dam properties from seismic response data, in order to consider the nonuniform excitation of the seismic input and to describe the global behavior of the dam, the multiple input/multiple output discrete-time ARX model with least square estimation is applied to identify the dynamic characteristics of the dam. The system modal frequency, damping ratio and frequency response function are identified from both the forced vibration and seismic response data. To verify the accuracy of the identification result, comparison between discrete-time ARX model and a frequency domain conditioned spectral analysis was made. Finally, the spatial variation of ground motion across the free-field canyon surface is also studied.     

Boundary spanning regimes and public policy change: the convergence of welfare and immigration policies

The concept of boundary spanning regimes has emerged to describe activity across policy subsystems that seek to manage ‘wicked’ public policy problems. This paper examines two existing public policy theories, namely those of exogenous shocks and the Advocacy Coalition Framework theories and assesses their capacity to explain why boundary spanning regimes emerge. It argues that broad structural conditions play an important role in shaping boundary spanning activity in the case studies discussed in this paper, indicating limitations in these theories which tend to overlook such conditions. The paper tests the explanations for policy change through original qualitative analysis of incremental convergence across the welfare and immigration policy fields in Australia from 1947 to 1996.     

Pillars and perspective: demarcation of the Belgian Congo–Northern Rhodesia boundary

From 1911 to 1914 an Anglo-Belgian boundary commission demarcated the 885 km boundary between the Belgian Congo and Northern Rhodesia along the watershed of the Congo and Zambezi rivers with a total of just 46 markers. Such low-density boundary demarcation with widely spaced pillars was typical of early British boundary-making in southern Africa. Less than fifteen years later, a second Anglo-Belgian boundary commission was created to re-demarcate the boundary. Not only was it unique for a colonial boundary in southern Africa to be re-demarcated, this second Anglo-Belgian boundary commission worked for six years with a budget that exceeded any previous British boundary commission in colonial Africa. This commission marked the Belgian Congo–Northern Rhodesia boundary on the ground with nearly five times the number of pillars as the first commission, literally etching the boundary in the African landscape. Its techniques of survey and boundary demarcation set a new standard, serving as a model for later British colonial boundary commissions and influencing boundary-making theory through the present day.     

Scattering problems of the SH Wave by Using the Null-Field Boundary Integral Equation Method

The scattering problem of seismic waves is an important issue for studying earthquake engineering. In this paper, the null-field boundary integral equation approach was used in conjunction with degenerate kernels and eigenfunction expansion to solve the SH-wave scattering problem of a circular or an elliptical-arc hill. The original problem is divided into subdomains by taking a free-body diagram. One region is an interior boundary value problem. The other is a canyon scattering problem. For the boundary value problem, not only a simply connected domain (elliptical-arc hill problem) but also a doubly connected domain (a circular-arc hill problem containing a circular tunnel or a circular inclusion) is considered. The canyon scattering problem may be addressed in an infinite domain with an artificial boundary of a full plane such that the degenerate kernel can be fully utilized. The null-field integral equation method is used to match boundary conditions. Numerical results are compared favorably with the available data.     

Evaluation of Side Boundary Effects on Dynamic Numerical Modeling for Centrifugal Model Tests

Four different boundary conditions consisting of fixed nodes, motion of roller only in the z or the x direction, and equivalent motion of two side boundaries were applied with a finite element code to simulate seismic behavior of two foundation conditions consisting of dry loose and dense sands. Comparing numerical results with physical model tests indicates that data obtained from the finite element code when considering soil nonlinearity with a sand model based on the tij concept have acceptable agreements with those from dynamic centrifuge tests regardless of the boundary conditions. The results from the boundary conditions of roller in the x direction and equivalent motion of two side boundaries agree well with the experimental data in wave peaks. The two side boundary conditions also keep the ground middle undisturbed and provide the results that are similar to those obtained from the wave amplification experimental data. For numerical simulations of centrifuge model tests, the side boundary condition with roller in the x direction is recommended because of low computation time and high simulation quality.     

万里长城的地理界线意义

长城,不仅是中华民族古老文化的象征,而且是一条实际存在的重要地理界线。历代长城的布设都是以自然地理环境为基础,其走向与我国半湿润与干旱气候分界线基本一致。因此,长城也就成为我国农区和牧区分界线的标志。长城的延伸或回退,基本上反映了农区与牧区的扩张或收缩。从政治地理的角度来考察长城。可以认为,它是我国历史上各民族政治力量相互对峙、较量形成的"力"的平衡带,长城,一方面发挥了分隔两个政治单元的功能,它们延伸或收缩在一定程度上反映了两种力量对比的变化;另一方面,在先进与落后两种势力的对撞中.客观上却促进了相互间经济和文化的交流,促进了不同民族的融合。今日长城作为领土扩张和防御的军事设施作用已不复存在。但是长城在地理上的许多界限指标意义仍然存在,它依然是许多地理事物的敏感地区。     

Linguistic boundaries and geopolitical interests: the Albanian boundary commissions, 1878–1926

Since 1999, there has been much debate within the international community on what the future status of the autonomous province of Kosovo should be. However, there seems to have been little consideration as to why the Ottoman vilayet of Kosovo and the other majority Albanian-speaking areas (now parts of Montenegro, western Macedonia and north-western Greece) did not become either independent or part of an independent Albanian state, despite the legacy of these decisions. Focussing on British policy and perceptions, this article explores the role of the great powers in the delimitation of Albanian boundaries, particularly in two boundary commissions in 1913 and 1914: one determining the southern Albanian boundary with Greece and the other concerning the northern and north-eastern boundary with Serbia and Montenegro. The first part of the article considers the influences and interactions of two sets of factors in the boundary deliberations: the declared rationale of creating nation-states in south-eastern Europe based upon ethnographic criteria (linguistic boundaries) and the competing role of geopolitical interests in their decision-making, focussing particularly upon British interests. It illustrates that the decisions made to delimit the newly independent Albanian state primarily reflected the resulting great power conflicts and compensations, rather than the professed ethnographic rationale. The second part of the article explores some of the consequences of the decisions made to delimit Albanian boundaries, especially in ‘ethnic’ or national terms.     

Study on Low-Frequency Characterizations of Pulse-Type Ground Motions through Multi-Resolution Analysis

This article makes an attempt to investigate the low-frequency characterizations of pulse-type ground motions through ground motion components instead of original records. A decomposed method based on multi-resolution analysis is introduced in this article. The accuracy and validity of the method is tested in frequency domain, time domain and dynamic response. A dataset of 398 low-frequency components is obtained after the decomposition of 91 typical pulse-type records. A probabilistic model to describe the proportion of low-frequency components in corresponding original ground motions is established. At last, the decomposed method is used to investigate the impulsive characterizations of pulse-type ground motions.     

达旺历史归属论

文章认为,门隅地方古代史是我国西藏地方史的一个组成部分,在与西藏地方史一道融入中华民族整体发展史的进程之中,达旺成为门隅政治、宗教、文化中心.英国入主阿萨姆后在相当长时期内沿袭了沿喜马拉雅山南侧坡脚的传统习惯线.1910年英属印度提出战略边界计划,谋图将传统边界线北移至山脊,目的在于建立封锁印度民族解放运动的防火墙.英国对战略边界在达旺地区的走向多次修改,但根本目的没有改变,是在不同形势下出于维护对印度殖民统治需要而做出的扩展或收缩的调整,战略边界计划及有关活动是英国单方面作为.直至1951年中国西藏地方政府仍然对达旺进行有效治理.     

Pseudo-Dynamic Testing and Analytical Modeling of AAC Infilled RC Frames

Two concrete frames were tested by the PsD procedure. One frame was bare and the other was infilled with AAC blocks in the middle bay. The objective was to determine the effect of AAC infills on the seismic performance of reinforced concrete frames and developing an AAC strut model. Based on the test results, it was found that AAC infill panels did not modify the deformation response of the RC test frame significantly; however, shear in diagonal strut must be considered in boundary column design. A shear design procedure is proposed for the boundary columns in infilled frames. The drift limits of AAC infill panels measured during the tests were 0.005, 0.008, and 0.014 during diagonal cracking, corner crushing, and severe damage states, respectively.     

对1689-1727年中俄外交关系的考察

中俄《尼布楚条约》签订后,双方围绕边界、逃人、贸易诸问题展开新一轮的交锋。本文主要针对1689—1727年中俄外交的主题、外交危机的爆发、两国外交举措、外交结果等内容进行较为系统的论述。     

Dynamic Interaction between Rigid Foundations on Multi-layered Stratum

This article concerns the cross-interaction problem among multi-foundations on a linearly viscoelastic medium at very small shear strains. In the analysis, the foundations are discretized into a number of sub square-elements. The dynamic response within each sub-element is described by the Green’s function, which is obtained by the Fourier-Bessel transform and the precise integration method. Incorporating the displacement boundary condition and the force equilibrium of the foundations, it obtains the dynamic impedance and compliance functions of the foundations. Extensive results for two rigid circular foundations placed at different separations are presented. Parametric studies are carried out on the dynamic interaction among adjacent foundations. Illustrative results for several closely spaced foundations are also illustrated.     

Evaluation of the Nonlinear Seismic Response of an Earth Dam: Nonparametric System Identification

A system identification framework is proposed to investigate the nonlinear dynamic response of massive earth dams using the seismic motion recorded by a sparse array of accelerometers. The framework includes a methodical step of nonparametric analyses to characterize the involved loading conditions and response mechanisms. This nonparametric step provides essential information to reduce the indeterminacy of the associated parametric identificatin problem and ensure a proper model selection, calibration, and validation. The proposed framework was applied to the Long Valley earth dam (California) and benchmarked using records of a series of 1980 earthquakes. This article presents the conducted correlation, spectral motion reconstruction, and nonparametric stress-strain analyses. These analyses revealed a complex three-dimensional dynamic response marked by non uniform boundary conditions and a shear stress-strain behavior slightly less nonlinear than what was observed in triaxial tests of soil samples taken from the dam core.     

"边疆"一词在世界主要法系中的镜像:一个语源学角度的考察

法系是比较法学的基础概念。本文主要利用语源学的方法,分析了世界三大主要法系——中华法系、罗马法系和伊斯兰法系——中领土、疆域、边疆等概念所反映的不同镜像,力图将不同的地方性知识构成较为全面的世界法律文化图景。     

Nature,space and distances in an imperial boundary network: The delimitation of the Nyasa-Tanganyika plateau boundary

This article discusses an episode of boundary delimitation/demarcation conducted between British and German imperial powers on the central African Nyasa-Tanganyika plateau in the late 1890s. I situate vignettes on the boundary's delimitation in 1897-98 within broader processes of imperial territorialisation to note that the boundary eventually produced on the plateau represented a fabrication resolving tensions between its ‘natural’ and textual sources. Specifically, I argue the boundary was produced to mediate between a diplomatic nature, written in metropolitan worlds by diplomats and cartographers, and a colonial nature, a zone of phenomenal experiences, inhuman encounters and ‘sensation’ (Wark, 2016). I emphasise the experience of technical practice to suggest that this itself represented a form of imperial power, capable of challenging or ‘deferring’ (Bhabha, 2012) metropolitan circuits of governance and knowledge production, not least by revealing the liveliness of the material world undergoing imperial territorialisation. Sensation produced the form of the writings and archives of survey-exploration: often confounded by problems of their data and surroundings, commissioners made the epistemological and subjective manoeuvrings through which they appeared to rise above their inert surroundings to master them. But this does not characterise the experience of fieldwork on the plateau, which was constituted by a panoply of technical situations wherein delineations between objects, observers and their material settings were indeterminable.     

The role of the Irish boundary commission in the entrenchment of the Irish border: from tactical panacea to political liability

The abortive saga of the Irish Boundary Commission has largely been dismissed as a minor footnote that warrants little elaboration in the discussion of Ireland's partition. This is unsurprising considering that its final report was hastily suppressed so as to prevent the destabilisation of the nascent regimes in Northern Ireland and the then Irish Free State. However, the concept of the Commission derives from the intensifying controversies of Irish Home Rule and partition, and the consequent difficulties in establishing how and where a boundary was eventually drawn as well as to the status of the entities it would be dividing. The Commission was legally conceived in Article 12 of the 1921 Anglo-Irish Treaty but confusion over its wording protracted a sequence of events that ensured that it was almost three years before it actually met. Article 12 was eventually interpreted in a restrictive manner, which exposed inherent flaws that were either ignored or naively underestimated when it was originally adapted from part of the post-World War I Treaty of Versailles. Furthermore, the complexities of evidence were inadequately scrutinised by a small and under-resourced panel that operated under considerable political pressure to delimit a precise line that satisfied subjective terms of reference. Nevertheless, the revoked Commission served as a crucial catalyst in defining the Irish Free State's relationship with the British State and in entrenching the territorial framework of Northern Ireland's six counties that exists to this day.     

A COMPARATIVE STUDY ON THE ACTUAL AND ESTIMATED SEISMIC RESPONSE OF KIRALKIZI DAM IN TURKEY

Kiralkizi Dam, a 120 m high earthfill dam located in Diyarbakir city, Turkey, was shaken by a moment magnitude, M _w =4.6 earthquake at an epicentral distance of 8 km, on December 24, 2000, at 13:31 local time. The seismic response of the dam was assessed by using spectral ratios between (i) available crest and foundation records (C/F), (ii) horizontal and vertical components of the recorded motions (H/V), (iii) by performing 2 dimensional finite difference-based seismic response analyses (Flac-2D), and (iv) ID elastic shear beam solutions. First mode of vibration of the dam in the transverse direction by all four methods were estimated in the range of 0.55 to 0.62 second. Similar close agreement was not observed in higher modal periods estimated by H/V technique as compared to the predictions by C/F, Flac-2D, shear beam analysis techniques. Thus, H/V technique was concluded to be useful for the estimation of the fundamental resonance frequency of a soil structure, but not for its higher harmonics as consistent with available limited literature. In the longitudinal direction, natural period of the dam was estimated as 0.28 and 0. 82 second by H/V and C/F techniques, respectively. Such disagreement was explained by (i) differences in the definitions of the estimated periods, (ii) internal impedance contrast of the dam, (iii) contributions of 3D valley effects. Single seismometer record obtained from crest level was found to be inadequate for reliably assessing the response of a dam in the longitudinal direction, and it is recommended to install multiple seismometers both within dambody and the abutments. Last but not least, the results of these analyses were further compared by available accelograms recorded at three earthfill and rocknll dams from Japan. In general, it was concluded that the seismic response of Kiralkizi Dam is comparable and within the prediction ranges of available analyses methods and is consistent with the expected response of a dam this height.