New Orleans Levee System Performance during Hurricane Katrina: London Avenue and Orleans Canal South

Hurricane Katrina was one of the worst natural disasters in U.S. history. The effects of the hurricane were particularly devastating in the city of New Orleans. Most of the damage was due to the failure of the levee system that surrounds the city to protect it from flooding. This paper presents the results of centrifuge models conducted at Rensselaer Polytechnic Institute and the U.S. Army Corps of Engineers simulating the behavior of the levees at London Avenue North and South that failed during Hurricane Katrina. Those levees failed without being overtopped by the storm surge. Also included are the results of a centrifuge model of one levee section at Orleans Canal South, which did not fail during the hurricane. The key factor of the failure mechanism of the London Avenue levees was the formation of a gap between the flooded side of the levee and the sheetpile. This gap triggered a reduction of the strength at the foundation of the protected side of the levee. The results are fully consistent with field observations.     

A duplex theory of hate: Development and application to terrorism, massacres, and genocide.

This article presents a triangular theory of the structure of hate and a story-based theory of the development of triangles of hate. Hate is proposed to be 1 contributing cause of many, although certainly not all, massacres and genocides. The article describes why the problem of terrorism, massacres, and genocide is of critical importance to psychology; reviews theories of the instigation of massacres and genocides; and then presents the duplex theory. The role of propaganda and other instigating factors is discussed. The benefits and limitations of the proposed duplex theory of hate are reviewed. Possible remedies for hate also are delineated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

自动化技术在露天金属矿山的应用实践

随着我国经济的快速发展,在自动化技术在露天金属矿山的应用实践方面也是相对重视起来,经济的快速发展间接影响着我国的矿山资源需求的增长,从对矿山连续生产的角度来看,新技术对于露天金属矿山的开采具有重要意义。露天金属矿山的开采技术的提出代表我国的自动化技术在露天金属矿山的应用实践到达了一个新的高度,对于国家的发展以及人民对于物质生活的越来越高的要求都从侧面激发着露天金属矿山的开采技术的研究发展。自动化技术在矿山生产中的充分运用,主要在矿山开采与生产效率上得到了充分的体现。     

Theory of Plastic Sand Flow with Fluid Pressure Effect

Fundamental principles of elastic–plastic mechanics of soils and rocks are given on the base of the original publications. The solid friction and dilatancy effects are included in the nonstandard form of nonassociative rule of plastic flow. The resulting hyperbolic system of equations is represented for a plane case. The slip surfaces are assumed to be jump tangential discontinuities of a velocity field. The possibility of limit equilibrium at slip surfaces is accounted for. The attempts to account for grain rotations, permitting study of slip surface structure, are discussed. The Biot–Frenkel model of interpenetrating continua is developed for plastic flow of porous saturated matrix. In this case the solid matrix state is determined by the effective stresses and pore pressure diffusion happens in plastically flowing matrix. To illustrate the theory possibilities, solutions for failure and mass sand flow, driven by the pore pressure gradient, are selected. They are important especially for oil/gas reservoirs with a weak matrix, typical for offshore geology.     

Anatomy of Turbulence Effects on the Aerodynamics of an Oscillating Prism

Turbulence-induced changes in aerodynamic force characteristics on an oscillating rectangular prism were investigated in this study. It encompassed examination of aeroelastic quantities, i.e., flutter derivatives, and the buffeting components of the integral forces. A forced-vibration system was employed to extract the aerodynamic characteristics of an oscillating prism using a model instrumented with multiple pressure transducers for synchronous scanning of the pressure field. Chordwise distributions of self-excited pressure amplitudes were measured and associated phases were derived to examine the anatomy of turbulence effects on the aerodynamics of the prism rather than simply discern the influence of turbulence on the integrated forces. The resulting changes in flutter derivatives were traced back to a turbulence-induced upstream shifting of the regions of maximum pressure amplitudes. This upstream shifting was consistent with earlier research showing that turbulence increases the radius of curvature of separated shear layers and moves reattachment upstream. In this study, turbulence was found to have a stabilizing effect on the aerodynamics of the prism. The broad band character of the buffeting forces was found to be quite similar to that of stationary prisms with body motion slightly increasing energy content.     

From the editors.

Introduces the articles appearing in this issue of Psychology of Aesthetics, Creativity, and the Arts. Of particular interest in this issue are the breadth and the rigor of the methodology that underlie the substantive and theoretical issues addressed in the work. The issue begins with an article from Dean Keith Simonton, who looks at the idea of what success in film is and how different indicators of success (critical, box office, etc.) are related to one another over the life of a film. Paul Silvia, James C. Kaufman, and Jean Pretz then address the question of the domain specificity of creativity. The third article shifts to the field of music and looks at the relationship between personality characteristics and how people use music in their lives. The next article reports the results of an experimental design that looked at recognition of objects in cubist paintings and pupil dilation after having made a classification of an object. The next article looks at differences in the motivations and personality characteristics of individuals who visit modern art museums versus ancient art museums. Next, Patricia Stokes uses the problem-solving approaches of Reitman and Simon in a case study examining the sculpture of Richard Serra. The issue concludes with an analysis of the idea of “lived experience” as it relates to the psychology of aesthetics and art making. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formation of Secondary Containment Systems Using Permeation of Colloidal Silica

U.S. Environmental Protection Agency (USEPA) regulations require the capture of spills from liquid tanks containing hazardous chemicals by using a secondary containment system. Compacted clay or geomembrane liners are commonly used in secondary containment systems, but they are cumbersome when used in conjunction with existing liquid tanks because of pipeline networks surrounding the tanks. This study evaluates the formation of hydraulic barriers for secondary containment through the permeation of colloidal silica grout. A simplified infiltration model is presented to predict the downward movement of the colloidal silica grout into a soil layer, considering the time-dependent increase in dynamic viscosity of the colloidal silica for different concentrations of an electrolyte accelerator. Because the simplified infiltration model cannot predict the soil-grout interaction or the permeation of the colloidal silica by fingering, its results were calibrated by using the observations from a large-scale column test involving the permeation of colloidal silica into sand. The predicted position of the wetting front was found to match that of the experiment when the parameter governing the change in viscosity of the colloidal silica was increased by a factor of 30. The infiltration model calibrated with observations from column infiltration experiments provides a simple approach to the design of the secondary containment systems using permeation of colloidal silica.     

Failure Analysis of a Bridge Embankment with Cracked Approach Slabs and Leaking Sand

This paper describes a successful failure analysis to determine the causes of loss of backfill sand from a mechanically stabilized earth (MSE) wall, and cracks on the concrete approach slabs on top of it. The Texas Department of Transportation was concerned that the cracks on the approach slabs may be related to the excessive loss of backfill from behind the MSE walls, and that the embankment structure may be unsafe due to potential voids under the concrete slab. Several cubic meters of sugar sand had washed out of the wall and deposited adjacent to the paneled walls. A series of destructive and nondestructive tests were carried out to determine the causes of the problems. It was found that the cracking of the approach slab and the loss of backfill were unrelated. Suggestions for resolving both problems were made based on this study.     

Damage Modeling of Saturated Rocks in Drained and Undrained Conditions

A new anisotropic damage model is proposed to describe the mechanical and poromechanical behavior of brittle rocks in drained and undrained conditions. Although phenomenological, the model is based on physical grounds of micromechanical analysis. Induced damage is represented by a second rank tensor, which is related to the density and orientation of microcracks. Damage evolution is related to propagation of the microcracks. The effective elastic compliance of the damaged material is obtained from a specific form of the Gibbs free enthalpy function. Irreversible damage-related strain due to residual opening of microcracks after unloading is also captured. The originality of our approach is that a poromechanical model of a saturated medium is constructed by extension of the mechanical model for dry material using micromechanical relationships. All the model parameters are determined from triaxial compression tests performed on dry material. The proposed model is applied to coupled poromechanical tests performed on typical brittle rock in saturated conditions. Comparison between test data and numerical simulations shows overall good agreement. The model proposed is able to describe the main features of poromechanical behavior related to microcracks induced in brittle geomaterials.     

Strain Localization in Combined Axial-Torsional Testing on Kaolin Clay

A series of combined axial-torsional tests were performed to study the 3D mechanical behavior of kaolin clay in an undrained condition. Using the digital image analysis technique, discrete local deformation of the surface of a hollow cylindrical specimen under loading was recorded. A linear interpolation method was used to generate a continuous deformation and strain field of the specimen based on the recorded discrete local deformations. Evolution of shear band was vividly visualized and recorded during the loading process for various inclinations of major principal stress. The theory of strain localization on continuous bifurcation was briefly reviewed and applied to the Mohr-Coulomb model, and a single hardening model incorporating the concept of loading-history-dependent plastic potential was developed by the writers. The largest critical plastic modulus and orientation of the shear bands were predicted by using the theoretical solution. Significant disagreement was observed between the experimental results and theoretical predictions related to the initial occurrence of strain localization and the inclination of fully developed shear bands.