Observations on static and cyclic sand-liquefaction methodologies

1992 ◽  
Vol 29 (4) ◽  
pp. 650-665 ◽  
Author(s):  
E. C. McRoberts ◽  
J. A. Sladen
Keyword(s):  
Steady State ◽  
Common Ground ◽  
Input Parameter ◽  
Liquefaction Potential ◽  
Sand Liquefaction ◽  
Cyclic Mobility ◽  
State Of Practice ◽  
Traditional Approaches ◽  
Future Work ◽  
Cyclic Approach

The paper focuses on a review of elements of the liquefaction of sand. Consideration is given to both the static and cyclic approach, and the bases for many of the divergent opinions that currently exist are given. The objective of the paper is to state the arguments and to explore common ground. By considering the inconsistencies that currently exist it is hoped that future work will address issues raised. The real difficulties associated with measurement of the parameters necessary for existing design approaches are highlighted. Because of these difficulties, it is prudent to consider several methods when evaluating liquefaction potential, and practising engineers must often rely on traditional approaches. The state of practice would be improved more by research to address these difficulties than by the development of more elaborate methods of analysis, which are often not justified by the level of precision associated with input parameter measurements. Key words : liquefaction, steady-state, cyclic mobility, critical state.

Rethinking the Naming of Sex Crime Victims

1995 ◽  
Vol 16 (3) ◽  
pp. 96-112 ◽  
Author(s):  
Jay Black
Keyword(s):  
Ethical Dilemma ◽  
Common Ground ◽  
Crime Victims ◽  
Sex Crimes ◽  
Traditional Approaches ◽  
Sex Crime

This commentary attempts to work through the news media's ethical dilemma of covering sex crimes so that victims' rights advocates and media personnel can find common ground. Traditional approaches to sex crimes—using craft-based, professionally oriented definitions of news—should be replaced with ethically principled orientations toward news once concerns over “rights” are augmented with concerns over “duties.”

Towards an Energy-Based Linear Analysis of Nonholonomic Systems

1999 ◽  
Author(s):  
Marwan Bikdash ◽  
Richard A. Layton
Keyword(s):  
Steady State ◽  
Singular Systems ◽  
Nonholonomic Constraints ◽  
Nonholonomic Systems ◽  
Linear Analysis ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Indirect Approach ◽  
Physical Systems ◽  
Future Work

Abstract Guidelines toward an energy-based, linear analysis of discrete physical systems are presented, based on previous work in systematic modeling using Lagrangian differential-algebraic equations (DAEs). Recent work in this area is extended by accommodating nonholonomic constraints and explicit inputs. An equilibrium postulate is proposed and equilibrium is characterized for static and steady-state conditions. Lagrangian DAEs are linearized using a local, indirect approach. Alternate descriptor formulations leading to different linear singular systems are compared and one formulation is determined to be a good foundation for future work in linear analysis using Lagrangian DAEs.

Finding Common Ground: COSO's Control Frameworks and the Levers of Control

2017 ◽  
Vol 31 (1) ◽  
pp. 63-83 ◽  
Author(s):  
Ramji Balakrishnan ◽  
Ella Mae Matsumura ◽  
Sridhar Ramamoorti
Keyword(s):  
Internal Control ◽  
Common Ground ◽  
Enterprise Risk Management ◽  
Organizational Control ◽  
Enterprise Risk ◽  
Operational Processes ◽  
Future Work ◽  
Levers Of Control ◽  
Partial Success ◽  
Do So

ABSTRACT We examine the extent to which the 2013 COSO Internal Control—Integrated Framework (ICIF) succeeds in the goal to expand its application beyond a compliance framework. We do so by mapping the points of focus in the 2013 ICIF to the principles articulated in the Levers of Control (LOC) framework advocated by Simons (1995). The analysis shows how the revision achieves partial success. This identification of areas in which the frameworks overlap promotes an integrated view of organizational control and aids assessment of the efficacy of a firm's control over its strategic and operational processes. We also examine the extent to which the 2016 COSO Enterprise Risk Management (ERM) Exposure Draft captures non-overlapping areas between the 2013 ICIF and the LOC, and highlight implications for future work in this evolving area.

Uniqueness of steady state and liquefaction potential

1994 ◽  
Vol 31 (1) ◽  
pp. 132-139 ◽  
Author(s):  
D. Negussey ◽  
M.S. Islam
Keyword(s):  
Steady State ◽  
Bedding Plane ◽  
Triaxial Tests ◽  
Initial State ◽  
Liquefaction Potential ◽  
Initial Anisotropy ◽  
Anisotropic Consolidation ◽  
Stress States ◽  
Undrained Loading ◽  
Loading Form

A given sand is presumed to have a unique steady-state line. The proximity of an initial state to the steady-state line is considered to be a measure of liquefaction potential. This line of reasoning and application in practice is based on data obtained predominantly from triaxial tests in compression-mode loading. In such tests, relative orientations of bedding plane and principal stress directions remain fixed while stress states along actual failure surfaces may range from active to passive. This study examines the uniqueness of the steady state relative to the mode of loading, form of consolidation, and initial anisotropy as induced by bedding orientation. A sample-preparation method was developed to form triaxial samples with different bedding orientations. Steady states of a uniform sand reached under compressional and extensional modes of triaxial undrained loading of samples with different bedding orientation are compared. Effects of isotropic and anisotropic consolidation are examined. The results indicate the steady-state line obtained for compression-mode loading is different from and does not apply for extension-mode loading. Use of a compression side steady-state line for extension-mode failure states would result in overestimation of steady-state strengths and unconservative stability evaluations. Key words : anisotropy, compression, extension, liquefaction, sand, steady state, triaxial.

scholarly journals The lifetimes of planetary debris discs around white dwarfs

2020 ◽  
Vol 496 (2) ◽  
pp. 2292-2308 ◽  
Author(s):  
Dimitri Veras ◽  
Kevin Heng
Keyword(s):  
Steady State ◽  
White Dwarf ◽  
White Dwarfs ◽  
Input Parameter ◽  
Evolutionary Constraints ◽  
Minor Planets ◽  
Evolutionary Models ◽  
Tidal Disruption ◽  
Different Types ◽  
Break Up

ABSTRACT The lifetime of a planetary disc that orbits a white dwarf represents a crucial input parameter into evolutionary models of that system. Here we apply a purely analytical formalism to estimate lifetimes of the debris phase of these discs, before they are ground down into dust or are subject to sublimation from the white dwarf. We compute maximum lifetimes for three different types of white dwarf discs, formed from (i) radiative YORP break-up of exo-asteroids along the giant branch phases at 2–100 au, (ii) radiation-less spin-up disruption of these minor planets at ${\sim} 1.5\!-\!4.5\, \mathrm{R}_{\odot }$, and (iii) tidal disruption of minor or major planets within about $1.3\, \mathrm{R}_{\odot }$. We display these maximum lifetimes as a function of disc mass and extent, constituent planetesimal properties, and representative orbital excitations of eccentricity and inclination. We find that YORP discs with masses of up to 1024 kg live long enough to provide a reservoir of surviving cm-sized pebbles and m- to km-sized boulders that can be perturbed intact to white dwarfs with cooling ages of up to 10 Gyr. Debris discs formed from the spin or tidal disruption of these minor planets or major planets can survive in a steady state for up to, respectively, 1 or 0.01 Myr, although most tidal discs would leave a steady state within about 1 yr. Our results illustrate that dust-less planetesimal transit detections are plausible, and would provide particularly robust evolutionary constraints. Our formalism can easily be adapted to individual systems and future discoveries.

Overview of the liquefaction assessment and seismic stability of Duncan Dam: Specialty session, 46th Annual Canadian Geotechnical Conference Saskatoon, Saskatchewan, September 27–29, 1993

1994 ◽  
Vol 31 (6) ◽  
pp. 918-918
Author(s):  
Alan S. Imrie
Keyword(s):  
Key Words ◽  
Deformation Behaviour ◽  
Seismic Stability ◽  
Dam Safety ◽  
Safety Study ◽  
Liquefaction Potential ◽  
Glacial Sediments ◽  
Current State ◽  
State Of Practice ◽  
Liquefaction Assessment

This overview introduces a series of six papers describing the approach taken in a recent dam safety study to evaluate the liquefaction potential and deformation behaviour for the current seismic setting of Duncan Dam. The dam was originally designed and built in the mid-1960s and is an embankment structure founded on a thick sequence of glacial sediments. The papers were initially presented by a team of B.C. Hydro and their consultants at a specialty session held at the 46th Annual Canadian Conference in Saskatoon in September 1993. The papers provide an excellent summary of the current state of practice in evaluating liquefaction and post-liquefaction behaviour. Key words : embankment, liquefaction, seismic, specialty session.

A Testability and Observability Framework to Assure Traceability Requirements on System of Systems

2020 ◽  
Author(s):  
Leticia Morales Trujillo ◽  
Miguel Ángel Olivero González ◽  
Francisco José Domínguez Mayo ◽  
Julián Alberto García García ◽  
Manuel Mejías Risoto
Keyword(s):  
Assisted Reproduction ◽  
Essential Feature ◽  
System Of Systems ◽  
Continuous Integration ◽  
Early Stages ◽  
Full Coverage ◽  
Digital World ◽  
Traditional Approaches ◽  
Future Work

The advance in the digital world has caused a growth of complexity in innovation. Traditional approaches to innovation, based on reductionism, face greater difficulties. That is why we have witnessed the growth of those known as System of Systems (SoS). There is a wide variety of methodologies and domains of application in the literature to form framed solutions in the context of SoS, but there is no unified consensus for its use and even less when it comes to agile environments of continuous integration and deployment in which traceability requirements are critical. In recent years, the need to have traceability software that continuously records and monitors the trace of the entities that interact with it has become an essential feature. In addition, over the years there has been evidence of errors caused by poor traceability control. Therefore, this document presents an agile framework that aims to guarantee the traceability of a SoS from the early stages. This framework unifies the discovery, development and operations, providing full coverage in the conformation of the solution. Finally, we present a case study as future work, which is based on the application of our framework on smart laboratories for assisted reproduction.

Evaluation of liquefaction potential of foundation soils at Duncan Dam

1994 ◽  
Vol 31 (6) ◽  
pp. 951-966 ◽  
Author(s):  
V.S. Pillai ◽  
R.A. Stewart
Keyword(s):  
Engineering Properties ◽  
Soil Parameters ◽  
Confining Stress ◽  
Undisturbed Soil ◽  
Liquefaction Potential ◽  
Sand Liquefaction ◽  
Cyclic Resistance ◽  
And Performance ◽  
Design Earthquake ◽  
The Right

A comprehensive program of field, laboratory, and analytical investigations was carried out to evaluate the potential of liquefaction for the foundation soils at Duncan Dam. Duncan Dam was completed in 1967 under the Columbia River Treaty in southeastern British Columbia. The 39 m high zoned embankment dam is founded on a sequence of sands, silts, and gravels. Some of the foundation soils may liquefy during earthquake loading and this would affect the stability and performance of the dam. The liquefaction studies were carried out in two phases to characterize the engineering properties of the foundation soils and to assess its potential for triggering liquefaction using the total stress approach. This paper describes methods of assessment of liquefaction potential using soil parameters based on field penetration data (Seed's method) and laboratory testing of undisturbed soil samples obtained in situ after freezing the ground (Lab method) and presents the results of triggering analysis. Influence of confining stress (Kσ) and initial static shear stress (Kα) on liquefaction were investigated and site-specific Kσ and Kα curves were developed.For the design earthquake (M 6.5, PGA = 0.12g) both the Lab method and Seed's method predict a significant extent of liquefaction of the foundation soils under the downstream slope in the right half of the dam. Key words : sand, liquefaction, confining stress, density, cyclic resistance ratio.

scholarly journals Take advantage of time in your experiments: a guide to simple, informative kinetics assays

2013 ◽  
Vol 24 (8) ◽  
pp. 1103-1110 ◽  
Author(s):  
Thomas D. Pollard ◽  
Enrique M. De La Cruz
Keyword(s):  
Steady State ◽  
Molecular Biology ◽  
Kinetic Parameters ◽  
Biological Process ◽  
Transient State ◽  
Cellular Systems ◽  
Biochemical Reactions ◽  
Enzyme Reactions ◽  
Traditional Approaches

Understanding virtually any process in cellular and molecular biology depends on knowledge of the rates of the biochemical reactions, so it is regrettable that few cellular and molecular biologists take advantage of kinetics experiments in their work. Fortunately, the kinetics experiments that are most useful for understanding cellular systems are within reach for everyone whose research would benefit from this information. This essay describes simple methods to measure the valuable kinetic parameters that characterize the dynamics of life processes. These “transient-state” methods not only differ in concept from traditional approaches used to analyze enzyme reactions at steady state, but they are also applicable to learning about the dynamics of any biological process.

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