scholarly journals ASSESSING THE SAFETY OF EXISTING STRUCTURES: RELIABILITY BASED ASSESSMENT FRAMEWORK, EXAMPLES AND APPLICATION

2004 ◽  
Vol 10 (2) ◽  
pp. 131-141
Author(s):  
Luc Schueremans ◽  
Dionys Van Gemert
Keyword(s):  
Assessment Framework ◽  
City Wall ◽  
Existing Structures ◽  
Surface Splines ◽  
Model Response ◽  
Low Degree ◽  
Key Issues ◽  
Reliability Methods ◽  
Reliability Algorithms ◽  
The Stability

Safety, reliability and risk are key issues in the preservation of our built, cultural heritage. Several structural collapses make us aware of the vulnerability of our technical and natural environment and demand an adequate engineering response. In the analysis phase, an objective way to assess the safety of the structure is essential. The present raises the need for a reliability based assessment framework for existing masonry structures. Although this field of research is relatively young, different techniques have been proposed and optimised. These permit to calculate the global probability of failure of complex structures, relying on deterministic techniques able to calculate the stability state for a prescribed set of parameters. This paper illustrates how these techniques can be a valid tool to evaluate the bearing capacity of existing structures. Focus is on reliability methods based on simulation procedures (Monte Carlo, Directional Sampling), combined with an adaptive meta‐model (Response Surface, Splines, Neural Networks). Several benchmark examples demonstrate the applicability of the methodology. The mutual efficiency of the different reliability algorithms is discussed. The application focuses on the assessment of an existing masonry structure. The overall stability of a Romanesque city wall of Leuven (B) is studied in detail. The analysis treats the present safety of the city wall, regarding the uncertainties in load, geometry and resistance. Because of the low degree of safety of several parts of the wall, consolidation measures and strengthening techniques are proposed.

Domains and Types of Aeroelastic Instability of Slender Beam

2007 ◽  
Author(s):  
Jirˇi´ Na´prstek
Keyword(s):  
Stability Boundary ◽  
Stability Loss ◽  
Stability Domain ◽  
Theoretical Explanation ◽  
Point Of View ◽  
System Response ◽  
Physical Point ◽  
Model Response ◽  
Gyroscopic Forces ◽  
The Stability

Slender structures exposed to a cross air flow are prone to vibrations of several types resulting from aeroelastic interaction of a flowing medium and a moving structure. Aeroelastic forces are the origin of nonconservative and gyroscopic forces influencing the stability of a system response. Conditions of a dynamic stability loss and a detailed analysis of a stability domain has been done using a linear mathematical model. Response properties of a system located on a stability boundary together with tendencies in its neighborhood are presented and interpreted from physical point of view. Results can be used for an explanation of several effects observed experimentally but remaining without theoretical explanation until now.

scholarly journals Pozycja w systemie władzy USA oraz zadania Rady ds. Monitorowania Stabilności Finansowej

2017 ◽  
pp. 61-74
Author(s):  
Wojciech Kwiatkowski
Keyword(s):  
United States ◽  
Financial Sector ◽  
The United States ◽  
Point Of View ◽  
Federal Law ◽  
The Us ◽  
Finance Company ◽  
Key Issues ◽  
The Stability ◽  
Financial Company

Present article discusses some of the key issues introduced to the US federal law in 2010 to ensure the stability of the financial sector in the United States. Special attention was paid to two issues, i.e. the rules and procedures under which the FSOC may considered a non-banking finance company to be important from the point of view of stability of the US financial sector (and in such situation trigger supplementary supervision by the FRS) and the procedure for controlled liquidation of a financial company considered by the FSOC to be a risk to the stability of the US financial system.

The Evolution of Gasses in Fire Suppression Systems to Promote Changes in Industrial Towards Global Sustainability

2021 ◽  
Vol 1025 ◽  
pp. 259-264
Author(s):  
Jum’azulhisham bin Abdul Shukor ◽  
Rahim Jamian ◽  
Azmi Hassan ◽  
Muhammad Al Hapis Abdul Razak
Keyword(s):  
Fire Suppression ◽  
Sudden Change ◽  
Montreal Protocol ◽  
Fire Extinguishing ◽  
Clean Agent ◽  
Key Issues ◽  
Greenhouse Effects ◽  
The Stability ◽  
Fundamental Equations ◽  
In Fire

The historical development of fire suppression technology evolved in the 1930s since the application of Halons as a fire extinguishing agent. The fire may cause tremendous losses to organizations. It affects the chain of businesses and the stability of the economic growth of a country. The key issues of greenhouse effects and safety and health as well contributes to the sudden change of the technology of fire extinguishing systems. The establishment of the Montreal Protocol and Kyoto Protocols controls the producers to develop, supply and use of environmentally hazardous gasses worldwide. Hence, promote global sustainable for upcoming generations. This paper is highlighting the reasons gas type fire extinguishing agents extensively used substituting conventional methods against fire. The fundamental equations of Ozone Depleting Potential and Global Warming Potential were properly discussed to show how severe these gasses exposed to the environment. The effectiveness of these gases as a clean agent in extinguishing the fire may convince prospect users to carry out the decision of changes. Potential extinguishing agents will be deliberated to investigate their needs as new fire suppression agents. It will be then to be suggested and recommended for further studies.

Research on Collapse Failure Process and Mechanism of Earthen Sites under the Action of Capillary Water

2013 ◽  
Vol 438-439 ◽  
pp. 1226-1231
Author(s):  
Gang Zhao ◽  
Ke Bin Ren ◽  
Qing Wen Ma
Keyword(s):  
Slope Failure ◽  
Failure Process ◽  
Soil Slope ◽  
Capillary Water ◽  
Protection Measures ◽  
City Wall ◽  
Ancient City ◽  
Collapse Failure ◽  
The Stability ◽  
Specific Project

Due to the particularity of the ancient city wall, the collapse damage of ancient city wall earthen ruins is different from general soil slope failure. Through on-site observations and theoretical analysis, collapse failure process and mechanism of ancient city wall earthen sites under the action of capillary water is studied, and protection measures are proposed. Collapse failure process of earthen sites under the action of capillary water has the characteristics of particularity, diversity and stage. Capillary water reduces the stability of ancient city wall by changing the soil physical properties, chemical and ice split role. Finally, the effect of capillary water is illustrated through a specific project example.

The Imperfection Sensitivity of Sheet Space Structure Based on the Contact Interactive

2012 ◽  
Vol 204-208 ◽  
pp. 1260-1266
Author(s):  
Tian Jiao Jin ◽  
Xiao Ming Guo ◽  
Wei Sun
Keyword(s):  
Critical Load ◽  
Space Structure ◽  
Space Structures ◽  
Imperfection Sensitivity ◽  
Distribution Law ◽  
Sample Number ◽  
Key Issues ◽  
Initial Geometric Imperfections ◽  
The Stability ◽  
Quantitative Indicators

The initial geometric imperfections and the contact problem between sheets and skeletons are two key issues of the stability analysis of sheet space structures. In this paper ,the distribution law of the critical load is found out, the appropriate sample number and the critical load value formula are chosen for stochastic imperfection method, while the value of probability reliability is ensured. The results of contact model and fully coordinated model are compared to indicate that the effect of contact must be considered in the imperfection sensitive analysis of the structure after stochastic imperfection sensitivity analysis of sheet space structures. The paper also raises the quantitative indicators to characterize the imperfection sensitivity of sheet space structure, and it is the necessary preparation to quantify the sensitivity of structures.

DEVELOPING SELECTIVE OXIDATION CATALYSTS OF LIGHT ALKANES: FROM FUNDAMENTAL UNDERSTANDING TO RATIONAL DESIGN

2007 ◽  
Vol 14 (04) ◽  
pp. 645-656 ◽  
Author(s):  
GANG FU ◽  
XIAODONG YI ◽  
CHUANJING HUANG ◽  
XIN XU ◽  
WEIZHENG WENG ◽  
...  
Keyword(s):  
Selective Oxidation ◽  
Rational Design ◽  
Acid Sites ◽  
Active Components ◽  
Active Centers ◽  
Light Alkanes ◽  
Key Issues ◽  
Spatial Isolation ◽  
Oxygen Anions ◽  
The Stability

Selective oxidation of light alkanes remains to be a great challenge for the wider use of alkanes as feedstocks. To achieve high activity and at the same time high selectivity, some key issues have to be addressed: (1) the stability of the desired products with respect to the reactants; (2) the roles of the active components in the catalysts, the structure and the functionality of the active centers; (3) the reducibility of the metal cations, the Lewis acid sites and their synergic effects with the basic sites of the lattice oxygen anions; (4) spatial isolation of the active centers; and (5) the mechanisms for the formation and transformation of the intermediates and their kinetic controls. In this contribution, we took selective oxidation of propane to acrolein as our target reaction, and reviewed mainly our own work, trying to provide some thinking and answers to these five questions.

Geotechnical and groundwater geophysics

Geophysics ◽  
1985 ◽  
Vol 50 (12) ◽  
pp. 2621-2636 ◽  
Author(s):  
T. L. Dobecki ◽  
P. R. Romig
Keyword(s):  
Construction Projects ◽  
New Technology ◽  
Petroleum Reservoir ◽  
Field Methods ◽  
Existing Structures ◽  
Reflection Seismic ◽  
Proper Role ◽  
Healthy State ◽  
Reservoir Description ◽  
The Stability

Because of a change in emphasis from power plant siting to projects principally involving process and facility monitoring and certification of existing structures (dams, pipelines, etc.), geotechnical and groundwater geophysics is in quite a healthy state after some lean years following the demise of nuclear energy construction projects. The orders‐of‐magnitude jump in the computational capability of geophysicists working in these fields has overshadowed advances in instrumentation (e.g., digital enhancement seismographs), field methods (e.g., cross‐borehole EM), and interpretive procedures. The advent of powerful, affordable microcomputers has enabled expansion into applications demanding finer resolution and quicker turnaround of results. As a result, shallow seismic reflection, seismic and electromagnetic geotomography, and the complementary use of surface and borehole electrical resistivity and seismic data will soon be common if not dominant methods in geotechnical and groundwater investigations. Future trends point to increased emphasis on environmental and economic issues (e.g., toxic wastes or the stability of underground petroleum storage facilities), cross‐fertilization with petroleum reservoir engineering (process monitoring and detailed reservoir description), and greater involvement of computers in the planning, data acquisition, and interpretive phases of our projects. As computers take over more of the data collection‐processing‐interpretation sequence, one of the greatest challenges facing us will be to define the proper role of humans and to use the new technology wisely.

scholarly journals The stability of paintings and the molecular structure of the oil paint polymeric network

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Francesca Nardelli ◽  
Francesca Martini ◽  
Judith Lee ◽  
Anna Lluvears-Tenorio ◽  
Jacopo La Nasa ◽  
...  
Keyword(s):  
Paint Film ◽  
Paint Layer ◽  
Surface Cleaning ◽  
Art Conservation ◽  
Polymeric Network ◽  
Low Degree ◽  
The Stability ◽  
Oil Paints ◽  
High Degree ◽  
First Time

AbstractA molecular-level understanding of the structure of the polymeric network formed upon the curing of air-drying artists’ oil paints still represents a challenge. In this study we used a set of analytical methodologies classically employed for the characterisation of a paint film—based on infrared spectroscopy and mass spectrometry—in combination with solid state NMR (SSNMR), to characterise model paint layers which present different behaviours towards surface cleaning with water, a commonly applied procedure in art conservation. The study demonstrates, with the fundamental contribution of SSNMR, a relationship between the painting stability and the chemical structure of the polymeric network. In particular, it is demonstrated for the first time that a low degree of cross-linking in combination with a high degree of oxidation of the polymeric network render the oil paint layer sensitive to water.

scholarly journals Key Issues in Global Technological Innovation Projects

2012 ◽  
Vol 3 (1) ◽  
pp. 04-28
Author(s):  
Marcos Roberto Piscopo ◽  
Roberto Sbragia
Keyword(s):  
Technological Innovation ◽  
Multinational Enterprises ◽  
Moderate Degree ◽  
Business Results ◽  
Iron Triangle ◽  
Low Degree ◽  
Innovation Projects ◽  
Key Issues ◽  
Performance Dimensions ◽  
High Degree

This article aimed to identify those issues that were present in global technological innovation projects carried out by Brazilian multinational companies and which performance criterions these undertakings met. We investigated 36 global technological innovation projects from Brazilian multinational enterprises through a web-survey. Findings show that these companies went beyond the traditional iron triangle to evaluate their technological efforts and considered additional performance dimensions such as customer satisfaction, business results, and preparation for the future. Results also show high degree of presence for issues emerging from the industry, moderate degree of presence for issues emerging from both the project and R&D activities, and low degree of presence for issues emerging from the headquarters, the subsidiaries, and the external environment. Further research is needed to find out if and how these issues influenced the performance of the global technological innovation projects studied.DOI:10.5585/gep.v3i1.72

scholarly journals Work Standardisation in Logistics Processes

2017 ◽  
Vol 21 (2) ◽  
pp. 109 ◽  
Author(s):  
Martina Džubáková ◽  
Michal Kopták
Keyword(s):  
Process Improvement ◽  
Time Measurement ◽  
Added Value ◽  
Human Potential ◽  
New Approach ◽  
External Regulation ◽  
Low Degree ◽  
Individual Variations ◽  
The Stability

<p><strong>Purpose:</strong> The article presents a concept of synergy between MTM (Methods Time Measurement) and TWI (Training within the Industry) methods through a case study conducted on elementary logistics processes. MTM brings optimisation into logistics operations and creates quality and efficiency standards. TWI provides the means of application of these standards at work to drive improvement.</p><p><strong>Methodology/Approach:</strong> To show a prospective viability/added value of the MTM and TWI combination, we present a case study involving simple logistics processes. We use the MTM as a standardisation method and the TWI as a variability control and process improvement concept.</p><p><strong>Findings:</strong> The MTM times generally determined as an external regulation, may not reflect the level of skills of workers in a specific company and often create a barrier to internal improvement. The concept of work standardisation based on the MTM method synergised with the TWI creates a dynamic improving system.</p><p><strong>Research Limitation/implication:</strong> Individual variations in the processes need to be accounted for and the terminology of current optimisation method and improvement concept need to be adapted accordingly in the present analysis. The methods of MTM and TWI employed in our study now slowly penetrate the logistics processes.</p><strong>Originality/Value of paper:</strong> The paper introduces a new approach to the methodology of internal logistics improvement. The MTM work standards increase the stability and productivity in logistics. However, they often hinder the change by allowing for only low degree of flexibility. Combining them with the concept of TWI, we can enhance quality and foster the human potential to change.

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