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摄影之友 2024年第6期 64-71页

作者：健一黄功吾(图) 不详

在历史的长河中,有些瞬间是如此强烈,以至于它们永远地刻录在我们的记忆中。对于许多美国人来说,越南战争就是这样一个时刻,而黄功吾(nick Ut)所拍摄的一张照片则成了那个时代的象征。

关键词：越南战争刻录照片

Risk of shear failure and extensional failure around over-stressed excavations in brittle rock

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 210-225页

作者： nick Barton Baotang Shen nick Barton&Associates OsloNorway CSIRO Energy BrisbaneAustralia

The authors investigate the failure modes surrounding over-stressed tunnels in *** lines of investigation are employed:failure in over-stressed three-dimensional(3D) models of tunnels bored under 3D stress,failure modes in two-dimensional(2D) numerical simulations of 1000 m and 2000 m deep tunnels using FRACOD,both in intact rock and in rock masses with one or two joint sets,and finally,observations in TBM(tunnel boring machine) tunnels in hard and medium hard massive *** reason for 'stress-induced' failure to initiate,when the assumed maximum tangential stress is approximately(0.4-0.5)σ_c(UCS,uniaxial compressive strength) in massive rock,is now known to be due to exceedance of a critical extensional strain which is generated by a Poisson's ratio ***,because similar 'stress/strength' failure limits are found in mining,nuclear waste research excavations,and deep road tunnels in Norway,one is easily misled into thinking of compressive stress induced *** of this,the empirical SRF(stress reduction factor in the Q-system) is set to accelerate as the estimated ratio σ_(θmax)/σ_c >> *** mining,similar 'stress/strength' ratios are used to suggest depth of *** reality behind the fracture initiation stress/strength ratio of '0.4' is actually because of combinations of familiar tensile and compressive strength ratios(such as 10) with Poisson's ratio(say0.25).We exceed the extensional strain limits and start to see acoustic emission(AE) when tangential stress σθ ≈ 0.4σc,due to simple *** combination of 2D theoretical FRACOD models and actual tunnelling suggests frequent initiation of failure by 'stable' extensional strain fracturing,but propagation in 'unstable' and therefore dynamic *** the case of very deep tunnels(and 3D physical simulations),compressive stresses may be too high for extensional strain fracturing,and shearing will dominate,both ahead of the face and following the *** shallower,the conc

关键词： Fracture propagation Tension Shear Poisson’s ratio Break-out Rock burst Deep tunnels FRACOD model

Prediction and Control of Distortion and Residual Stresses in Electron Beam Welding

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稀有金属材料与工程 2011年第S4期40卷 26-29页

作者： nick Bagshawa Chris Punshona TWI Ltd Granta ParkGreat AbingtonCambridgeCB21 6ALUK

Electron beam welding is recognized as an attractive method for minimizing distortion during welding,and is used frequently to join parts which are already finally machined or close to finished *** such cases,before EB welding,it is of great value to be able to estimate the level of accuracy that will be achieved and the dimensional stability of the assembly throughout its service *** presentation describes the development of a finite element (FE) modelling technique,validated by experiment,for predicting and understanding the development of residual stresses and distortion during EB welding,particularly in circular *** use of this method for optimization of welding procedures and residual stress mitigation methods is described and illustrated through a number of practical examples.

关键词： EB welding residual stress distortion

Computational fluid dynamics simulation of Hyperloop pod predicting laminar–turbulent transition

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Railway Engineering Science 2020年第1期28卷 97-111页

作者： Nathalie nick Yohei Sato Department of Mechanical and Process Engineering Swiss Federal Institute of TechnologyETH ZurichLEO B 9.1Leonhardstrasse 278092 ZurichSwitzerland Nuclear Energy and Safety Research Division Paul Scherrer InstituteForschungsstrasse 1115232 Villigen PSISwitzerland

Three-dimensional compressible flow simulationswere conducted to develop a Hyperloop pod. Thenovelty is the usage of Gamma transition model, in whichthe transition from laminar to turbulent flow can be ***, a mesh dependency study was undertaken,showing second-order convergence with respect to themesh refinement. Second, an aerodynamic analysis for twodesigns, short and optimized, was conducted with thetraveling speed 125 m/s at the system pressure 0.15 *** concept of the short model was to delay the transitionto decrease the frictional drag;meanwhile that of theoptimized design was to minimize the pressure drag bydecreasing the frontal area and introduce the transitionmore toward the front of the pod. The computed resultsshow that the transition of the short model occurred moreon the rear side due to the pod shape, which resulted in 8%smaller frictional drag coefficient than that for the optimizedmodel. The pressure drag for the optimized designwas 24% smaller than that for the short design, half ofwhich is due to the decrease in the frontal area, and theother half is due to the smoothed rear-end shape. The totaldrag for the optimized model was 14% smaller than that forthe short model. Finally, the influence of the systempressure was investigated. As the system pressure and theReynolds number increase, the frictional drag coefficientincreases, and the transition point moves toward the front,which are the typical phenomena observed in the transitionregime.

关键词： Computational fluid dynamics(CFD) Drag Subsonic compressible flow Hyperloop Laminar-turbulent transition

The boring billion? - Lid tectonics, continental growth and environmental change associated with the Columbia supercontinent

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Geoscience Frontiers 2013年第6期4卷 681-691页

作者： nick M.W.Roberts NERC Isotope Geosciences Laboratory British Geological SurveyKeyworthNottingham NG12 5GGUK

The evolution of Earth＇s biosphere,atmosphere and hydrosphere is tied to the formation of continental crust and its subsequent movements on tectonic *** supercontinent cycle posits that the continental crust is periodically amalgamated into a single landmass,subsequently breaking up and dispersing into various continental *** is possibly the first true supercontinent,it amalgamated during the 2.0-1.7 Ga period,and collisional orogenesis resulting from its formation peaked at 1.95-1.85 *** and palaeomagnetic evidence indicate that Columbia remained as a quasi-integral continental lid until at least 1.3 *** break-up attempts are evidenced by dyke swarms with a large temporal and spatial range; however,palaeomagnetic and geologic evidence suggest these attempts remained *** than dispersing into continental fragments,the Columbia supercontinent underwent only minor modifications to form the next supercontinent （Rodinia） at 1.1 -0.9 Ga; these included the transformation of external accretionary belts into the internal Grenville and equivalent collisional *** Columbia provides evidence for a form of ‘lid tectonics’,modern style plate tectonics occurred on its periphery in the form of accretionary *** detrital zircon and preserved geological record are compatible with an increase in the volume of continental crust during Columbia＇s lifespan; this is a consequence of the continuous accretionary processes along its *** quiescence in plate tectonic movements during Columbia＇s lifespan is correlative with a long period of stability in Earth＇s atmospheric and oceanic *** variability starting at 1.3 Ga in the environmental record coincides with the transformation of Columbia to Rodinia; thus,the link between plate tectonics and environmental change is strengthened with this interpretation of supercontinent history.

关键词： Rodinia Columbia Supercontinents Continental growth Lid tectonics Mesoproterozoic

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战地摄影:见证暴行,传承反战愿望

摄影之友 2024年第6期 62-63页

作者：周仰黄功吾(图) 英国伯明翰城市大学艺术学院英国威斯敏斯特大学不详

在2024年世界新闻摄影大赛(荷赛)中,巴以冲突和俄乌战争的摄影作品再次引起了人们对战争暴行的关注。然而,这些令人楸心的战地影像似乎未能引起我们足够的关注。与20世纪战地摄影师,如罗伯特·卡帕、唐·麦卡林和詹姆斯·纳切威等的作... 详细信息

在2024年世界新闻摄影大赛(荷赛)中,巴以冲突和俄乌战争的摄影作品再次引起了人们对战争暴行的关注。然而,这些令人楸心的战地影像似乎未能引起我们足够的关注。与20世纪战地摄影师,如罗伯特·卡帕、唐·麦卡林和詹姆斯·纳切威等的作品相比,如今的观众似乎更难为某一幅战地影像停留。这让我们不禁反思,战地摄影在当今社会的地位和影响力是否已经发生了变化?而传奇摄影师黄功吾的故事则让我们重新审视了战地摄影的意义和价值,以及它对历史的见证和反战愿望的传承。

关键词：摄影大赛摄影作品战地摄影巴以冲突历史的见证反战摄影师罗伯特·卡帕

Changes in the phenology of the ground beetle Pterostichus madidus

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Insect Science 2011年第4期18卷 462-472页

作者： Gabor Pozsgai nick A. Littlewood Macaulay Land Use Research IneUtute Craigiebuckler Aberdeen UK

A growing body of evidence shows that climate change can alter the phenology of plants and animals. In this study long-term data from the UK Environmental Change Network （ECN） were analyzed to investigate whether there has been a change in the phenology of the ground beetle Pterostichus madidus （Fabricius, 1775）. Pitfall trap data were available from 12 ECN sites across the United Kingdom, most of which have been in operation for more than 15 years. Weather and vegetation datasets were also utilized. Pitfall trap lines were categorized to eight vegetation types. Trend analysis over time was carried out first using all the available dates of capture events, then the datasets grouped by vegetation type and site. Shifts in high-activity periods were also analyzed. P madidus appearance dates advanced significantly at seven sites and in five vegetation types. Peak activity advanced at two sites. At one site the timing of activity became significantly later. The last day of activity did not change significantly, supporting the theory that the cessation of the activity period is more likely to be controlled by photoperiod than temperature. The relationships between phenological variables and climatic factors were also investigated. Howe＇ver, no significant correlations were detected. These results demonstrate that between 1992 and 2008, phenology ofP madidus at seven sites from the eight analyzed has changed. Global warming may be driving these changes and future work will investigate underlying processes.

关键词： black clock beetle climate change Environmental Change Network life-history long-term data trend analysis

Advances in joint roughness coefficient (JRC) and its engineering applications

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3352-3379页

作者： nick Barton Changshuo Wang Rui Yong nick Barton&Associates Fjordveien 65cHavik Oslo1363Norway School of Civil Engineeing Shijiazhuang Tiedao UniversityShijiazhuang050043China Rock Mechuanics Institute Ningbo UniversityNingbo315211China

The joint roughness coefficient (JRC), introduced in Barton (1973) represented a new method in rock mechanics and rock engineering to deal with problems related to joint roughness and shear strength estimation. It has the advantages of its simple form, easy estimation, and explicit consideration of scale effects, which make it the most widely accepted parameter for roughness quantification since it was proposed. As a result, JRC has attracted the attention of many scholars who have developed JRC-related methods in many areas, such as geological engineering, multidisciplinary geosciences, mining mineral processing, civil engineering, environmental engineering, and water resources. Because of such a developing trend, an overview of JRC is presented here to provide a clear perspective on the concepts, methods, applications, and trends related to its extensions. This review mainly introduces the origin and connotation of JRC, JRC-related roughness measurement, JRC estimation methods, JRC-based roughness characteristics investigation, JRC-based rock joint property description, JRC's influence on rock mass properties, and JRC-based rock engineering applications. Moreover, the representativeness of the joint samples and the determination of the sampling interval for rock joint roughness measurements are discussed. In the future, the existing JRC-related methods will likely be further improved and extended in rock engineering.

关键词： Joint roughness coefficient(JRC) Rock joints Roughness Shear strength Scale effect

Prediction of the Western North Pacific Subtropical High in Summer without Strong ENSO Forcing

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Journal of Meteorological Research 2021年第1期35卷 101-112页

作者： Chaofan LI Riyu LU nick DUNSTONE Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Met Office Hadley Centre Exeter EX13PBUK

The western North Pacific subtropical high(WNPSH) is one of the deterministic predictors of the East Asian summer climate, and a better prediction of the WNPSH favors more reasonable forecast of the East Asian summer climate. This study focuses on seasonal prediction of the WNPSH during neutral summers without strong El Ni?o–Southern Oscillation(ENSO) forcing, and explores the associated predictable sources, using the one-month lead time retrospective forecasts from the Ensembles-Based Predictions of Climate Changes and Their Impacts(ENSEMBLES) project during 1960–2005. The results indicate that the ENSEMBLES atmosphere–ocean–land coupled models exhibit considerable prediction skill for the WNPSH during neutral summers, with successful reproduction of the WNPSH in the majority of neutral summers. The anomalous WNPSH in neutral summers, which corresponds to cyclonic/anticyclonic anomalies in the lower troposphere, is highly correlated with an east–west dipole local sea surface temperature(SST) distribution over the tropical WNP, suggesting an intimate local air–sea coupling. Further diagnosis of the local SST–rainfall relationship and surface heat flux indicates that the anomalous local SST plays an active role in modulating the variation of the WNPSH during neutral summers, rather than passively responding to the atmospheric change. The local SST anomalies and relevant air–sea coupling over the tropical WNP are reasonably well reproduced in the model predictions, and could act as primary predictable sources of the WNPSH in neutral summers. This could aid in forecasting of the East Asian rainband and associated disaster mitigation planning.

关键词： western North Pacific subtropical high seasonal forecast neutral year air–sea interaction

Shear strength criteria for rock,rock joints,rockfill and rock masses:Problems and some solutions

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Journal of Rock Mechanics and Geotechnical Engineering 2013年第4期5卷 249-261页

作者： nick Barton nick Barton & Associates OsloNorway

Although many intact rock types can be very strong,a critical confining pressure can eventually be reached in triaxial testing,such that the Mohr shear strength envelope becomes *** critical state has recently been better defined,and correct curvature or correct deviation from linear Mohr-Coulomb（MC） has finally been *** shear testing procedures for rock joints,using multiple testing of the same sample,in case of insufficient samples,can be shown to exaggerate apparent *** rough joints do not have any cohesion,but instead have very high friction angles at low stress,due to strong *** masses,implying problems of large-scale interaction with engineering structures,may have both cohesive and frictional strength ***,it is not correct to add these,following linear M-C or nonlinear Hoek-Brown（H-B） standard *** is broken at small strain,while friction is mobilized at larger strain and remains to the end of the shear *** criterion ＇c then σn tan φ＇ should replace ＇c plus σn tan φ＇ for improved fit to *** of principal stresses to a shear plane seems to ignore mobilized dilation,and caused great experimental difficulties until *** seems to be plenty of room for continued research,so that errors of judgement of the last 50 years can be corrected.

关键词： Rock masses Critical state Rock joints Shear strength Non-linear friction Cohesion Dilation Scale effects Numerical modelling Stress transforms