Author: Isaac Elishakoff
Publisher: Springer Science & Business Media
ISBN: 9781402017797
Category : Science
Languages : en
Pages : 316
Book Description
Have you ever wondered where the safety factors come from? Why is it that deterministic analysis has reached a very sophisticated level, but in the end empirical factors are still needed? Is there a way to select them, rather than assigning them arbitrarily as is often done? This book clearly shows that safety factors are closely related with the reliability of structures, giving yet another demonstration of Albert Einstein's maxim that "It is incomprehensible that Nature is comprehensible". The book shows that the safety factors are much more comprehensible if they are seen in a probabilistic context. Several definitions of the safety factors are given, analytical results on insightful numbers are presented, nonprobabilistic safety factors are shown, as well as their estimates derived by the inequalities of Bienayme, Markov, Chebushev and Camp-Meidell. A special chapter is devoted to important contributions by Japanese experts. This volume will help to critically re-think the issue of safety factors, which can create a false feeling of security. The deterministic paradigm can be enhanced by incorporating probabilistic concepts wisely where they are needed without treating all variables as probabilistic ones. The book shows that there is a need of their integration rather than separation. This book is intended for engineers, graduate students, lecturers and researchers.
Safety Factors and Reliability: Friends or Foes?
Author: Isaac Elishakoff
Publisher: Springer Science & Business Media
ISBN: 9781402017797
Category : Science
Languages : en
Pages : 316
Book Description
Have you ever wondered where the safety factors come from? Why is it that deterministic analysis has reached a very sophisticated level, but in the end empirical factors are still needed? Is there a way to select them, rather than assigning them arbitrarily as is often done? This book clearly shows that safety factors are closely related with the reliability of structures, giving yet another demonstration of Albert Einstein's maxim that "It is incomprehensible that Nature is comprehensible". The book shows that the safety factors are much more comprehensible if they are seen in a probabilistic context. Several definitions of the safety factors are given, analytical results on insightful numbers are presented, nonprobabilistic safety factors are shown, as well as their estimates derived by the inequalities of Bienayme, Markov, Chebushev and Camp-Meidell. A special chapter is devoted to important contributions by Japanese experts. This volume will help to critically re-think the issue of safety factors, which can create a false feeling of security. The deterministic paradigm can be enhanced by incorporating probabilistic concepts wisely where they are needed without treating all variables as probabilistic ones. The book shows that there is a need of their integration rather than separation. This book is intended for engineers, graduate students, lecturers and researchers.
Publisher: Springer Science & Business Media
ISBN: 9781402017797
Category : Science
Languages : en
Pages : 316
Book Description
Have you ever wondered where the safety factors come from? Why is it that deterministic analysis has reached a very sophisticated level, but in the end empirical factors are still needed? Is there a way to select them, rather than assigning them arbitrarily as is often done? This book clearly shows that safety factors are closely related with the reliability of structures, giving yet another demonstration of Albert Einstein's maxim that "It is incomprehensible that Nature is comprehensible". The book shows that the safety factors are much more comprehensible if they are seen in a probabilistic context. Several definitions of the safety factors are given, analytical results on insightful numbers are presented, nonprobabilistic safety factors are shown, as well as their estimates derived by the inequalities of Bienayme, Markov, Chebushev and Camp-Meidell. A special chapter is devoted to important contributions by Japanese experts. This volume will help to critically re-think the issue of safety factors, which can create a false feeling of security. The deterministic paradigm can be enhanced by incorporating probabilistic concepts wisely where they are needed without treating all variables as probabilistic ones. The book shows that there is a need of their integration rather than separation. This book is intended for engineers, graduate students, lecturers and researchers.
Safety Factors and Reliability: Friends or Foes?
Author: Isaac Elishakoff
Publisher: Springer Science & Business Media
ISBN: 1402021313
Category : Technology & Engineering
Languages : en
Pages : 304
Book Description
Have you ever wondered where the safety factors come from? Why is it that deterministic analysis has reached a very sophisticated level, but in the end empirical factors are still needed? Is there a way to select them, rather than assigning them arbitrarily as is often done? This book clearly shows that safety factors are closely related with the reliability of structures, giving yet another demonstration of Albert Einstein's maxim that "It is incomprehensible that Nature is comprehensible". The book shows that the safety factors are much more comprehensible if they are seen in a probabilistic context. Several definitions of the safety factors are given, analytical results on insightful numbers are presented, nonprobabilistic safety factors are shown, as well as their estimates derived by the inequalities of Bienayme, Markov, Chebushev and Camp-Meidell. A special chapter is devoted to important contributions by Japanese experts. This volume will help to critically re-think the issue of safety factors, which can create a false feeling of security. The deterministic paradigm can be enhanced by incorporating probabilistic concepts wisely where they are needed without treating all variables as probabilistic ones. The book shows that there is a need of their integration rather than separation. This book is intended for engineers, graduate students, lecturers and researchers.
Publisher: Springer Science & Business Media
ISBN: 1402021313
Category : Technology & Engineering
Languages : en
Pages : 304
Book Description
Have you ever wondered where the safety factors come from? Why is it that deterministic analysis has reached a very sophisticated level, but in the end empirical factors are still needed? Is there a way to select them, rather than assigning them arbitrarily as is often done? This book clearly shows that safety factors are closely related with the reliability of structures, giving yet another demonstration of Albert Einstein's maxim that "It is incomprehensible that Nature is comprehensible". The book shows that the safety factors are much more comprehensible if they are seen in a probabilistic context. Several definitions of the safety factors are given, analytical results on insightful numbers are presented, nonprobabilistic safety factors are shown, as well as their estimates derived by the inequalities of Bienayme, Markov, Chebushev and Camp-Meidell. A special chapter is devoted to important contributions by Japanese experts. This volume will help to critically re-think the issue of safety factors, which can create a false feeling of security. The deterministic paradigm can be enhanced by incorporating probabilistic concepts wisely where they are needed without treating all variables as probabilistic ones. The book shows that there is a need of their integration rather than separation. This book is intended for engineers, graduate students, lecturers and researchers.
Philosophies of Structural Safety and Reliability
Author: Vladimir Raizer
Publisher: CRC Press
ISBN: 1000550729
Category : Technology & Engineering
Languages : en
Pages : 287
Book Description
Uncertainty is certain to be found in structural engineering, making it crucial to structure design. This book covers three competing philosophies behind structural safety and reliability: probabilistic analysis, fuzzy set-based treatments, and the convex approach. Explaining the theory behind probabilistic analysis, fuzzy set-based treatments, and the convex approach in detail, alongside their implementation, use, and benefits, the book compares and contrasts these methods, enabling the reader to solve problems associated with uncertainty. These uncertainty issues can be seen in civil engineering structures, risk of earthquakes, impact of rough seas on ships, and turbulence affecting aerospace vehicles. Building on the authors’ many years of experience in the field, Philosophies of Structural Safety and Reliability is an essential guide to structural uncertainty. Topics covered in the book include properties of materials and their structural deterioration, safety factor and reliability, risk evaluation and loads, and their combinations. This book will be of interest to students and professionals in the fields of aerospace, civil, mechanical, marine, and ocean engineering.
Publisher: CRC Press
ISBN: 1000550729
Category : Technology & Engineering
Languages : en
Pages : 287
Book Description
Uncertainty is certain to be found in structural engineering, making it crucial to structure design. This book covers three competing philosophies behind structural safety and reliability: probabilistic analysis, fuzzy set-based treatments, and the convex approach. Explaining the theory behind probabilistic analysis, fuzzy set-based treatments, and the convex approach in detail, alongside their implementation, use, and benefits, the book compares and contrasts these methods, enabling the reader to solve problems associated with uncertainty. These uncertainty issues can be seen in civil engineering structures, risk of earthquakes, impact of rough seas on ships, and turbulence affecting aerospace vehicles. Building on the authors’ many years of experience in the field, Philosophies of Structural Safety and Reliability is an essential guide to structural uncertainty. Topics covered in the book include properties of materials and their structural deterioration, safety factor and reliability, risk evaluation and loads, and their combinations. This book will be of interest to students and professionals in the fields of aerospace, civil, mechanical, marine, and ocean engineering.
Handbook of Safety Principles
Author: Niklas Möller
Publisher: John Wiley & Sons
ISBN: 1118950704
Category : Business & Economics
Languages : en
Pages : 830
Book Description
Presents recent breakthroughs in the theory, methods, and applications of safety and risk analysis for safety engineers, risk analysts, and policy makers Safety principles are paramount to addressing structured handling of safety concerns in all technological systems. This handbook captures and discusses the multitude of safety principles in a practical and applicable manner. It is organized by five overarching categories of safety principles: Safety Reserves; Information and Control; Demonstrability; Optimization; and Organizational Principles and Practices. With a focus on the structured treatment of a large number of safety principles relevant to all related fields, each chapter defines the principle in question and discusses its application as well as how it relates to other principles and terms. This treatment includes the history, the underlying theory, and the limitations and criticism of the principle. Several chapters also problematize and critically discuss the very concept of a safety principle. The book treats issues such as: What are safety principles and what roles do they have? What kinds of safety principles are there? When, if ever, should rules and principles be disobeyed? How do safety principles relate to the law; what is the status of principles in different domains? The book also features: • Insights from leading international experts on safety and reliability • Real-world applications and case studies including systems usability, verification and validation, human reliability, and safety barriers • Different taxonomies for how safety principles are categorized • Breakthroughs in safety and risk science that can significantly change, improve, and inform important practical decisions • A structured treatment of safety principles relevant to numerous disciplines and application areas in industry and other sectors of society • Comprehensive and practical coverage of the multitude of safety principles including maintenance optimization, substitution, safety automation, risk communication, precautionary approaches, non-quantitative safety analysis, safety culture, and many others The Handbook of Safety Principles is an ideal reference and resource for professionals engaged in risk and safety analysis and research. This book is also appropriate as a graduate and PhD-level textbook for courses in risk and safety analysis, reliability, safety engineering, and risk management offered within mathematics, operations research, and engineering departments. NIKLAS MÖLLER, PhD, is Associate Professor at the Royal Institute of Technology in Sweden. The author of approximately 20 international journal articles, Dr. Möller's research interests include the philosophy of risk, metaethics, philosophy of science, and epistemology. SVEN OVE HANSSON, PhD, is Professor of Philosophy at the Royal Institute of Technology. He has authored over 300 articles in international journals and is a member of the Royal Swedish Academy of Engineering Sciences. Dr. Hansson is also a Topical Editor for the Wiley Encyclopedia of Operations Research and Management Science. JAN-ERIK HOLMBERG, PhD, is Senior Consultant at Risk Pilot AB and Adjunct Professor of Probabilistic Riskand Safety Analysis at the Royal Institute of Technology. Dr. Holmberg received his PhD in Applied Mathematics from Helsinki University of Technology in 1997. CARL ROLLENHAGEN, PhD, is Adjunct Professor of Risk and Safety at the Royal Institute of Technology. Dr. Rollenhagen has performed extensive research in the field of human factors and MTO (Man, Technology, and Organization) with a specific emphasis on safety culture and climate, event investigation methods, and organizational safety assessment.
Publisher: John Wiley & Sons
ISBN: 1118950704
Category : Business & Economics
Languages : en
Pages : 830
Book Description
Presents recent breakthroughs in the theory, methods, and applications of safety and risk analysis for safety engineers, risk analysts, and policy makers Safety principles are paramount to addressing structured handling of safety concerns in all technological systems. This handbook captures and discusses the multitude of safety principles in a practical and applicable manner. It is organized by five overarching categories of safety principles: Safety Reserves; Information and Control; Demonstrability; Optimization; and Organizational Principles and Practices. With a focus on the structured treatment of a large number of safety principles relevant to all related fields, each chapter defines the principle in question and discusses its application as well as how it relates to other principles and terms. This treatment includes the history, the underlying theory, and the limitations and criticism of the principle. Several chapters also problematize and critically discuss the very concept of a safety principle. The book treats issues such as: What are safety principles and what roles do they have? What kinds of safety principles are there? When, if ever, should rules and principles be disobeyed? How do safety principles relate to the law; what is the status of principles in different domains? The book also features: • Insights from leading international experts on safety and reliability • Real-world applications and case studies including systems usability, verification and validation, human reliability, and safety barriers • Different taxonomies for how safety principles are categorized • Breakthroughs in safety and risk science that can significantly change, improve, and inform important practical decisions • A structured treatment of safety principles relevant to numerous disciplines and application areas in industry and other sectors of society • Comprehensive and practical coverage of the multitude of safety principles including maintenance optimization, substitution, safety automation, risk communication, precautionary approaches, non-quantitative safety analysis, safety culture, and many others The Handbook of Safety Principles is an ideal reference and resource for professionals engaged in risk and safety analysis and research. This book is also appropriate as a graduate and PhD-level textbook for courses in risk and safety analysis, reliability, safety engineering, and risk management offered within mathematics, operations research, and engineering departments. NIKLAS MÖLLER, PhD, is Associate Professor at the Royal Institute of Technology in Sweden. The author of approximately 20 international journal articles, Dr. Möller's research interests include the philosophy of risk, metaethics, philosophy of science, and epistemology. SVEN OVE HANSSON, PhD, is Professor of Philosophy at the Royal Institute of Technology. He has authored over 300 articles in international journals and is a member of the Royal Swedish Academy of Engineering Sciences. Dr. Hansson is also a Topical Editor for the Wiley Encyclopedia of Operations Research and Management Science. JAN-ERIK HOLMBERG, PhD, is Senior Consultant at Risk Pilot AB and Adjunct Professor of Probabilistic Riskand Safety Analysis at the Royal Institute of Technology. Dr. Holmberg received his PhD in Applied Mathematics from Helsinki University of Technology in 1997. CARL ROLLENHAGEN, PhD, is Adjunct Professor of Risk and Safety at the Royal Institute of Technology. Dr. Rollenhagen has performed extensive research in the field of human factors and MTO (Man, Technology, and Organization) with a specific emphasis on safety culture and climate, event investigation methods, and organizational safety assessment.
Modern Trends in Structural and Solid Mechanics 3
Author: Noel Challamel
Publisher: John Wiley & Sons
ISBN: 1786307189
Category : Science
Languages : en
Pages : 306
Book Description
This book comprised of three separate volumes presents the recent developments and research discoveries in structural and solid mechanics; it is dedicated to Professor Isaac Elishakoff. This third volume is devoted to non-deterministic mechanics. Modern Trends in Structural and Solid Mechanics 3 has broad scope, covering topics such: design optimization under uncertainty, interval field approaches, convex analysis, quantum inspired topology optimization and stochastic dynamics. The book is illustrated by many applications in the field of aerospace engineering, mechanical engineering, civil engineering, biomedical engineering and automotive engineering. This book is intended for graduate students and researchers in the field of theoretical and applied mechanics.
Publisher: John Wiley & Sons
ISBN: 1786307189
Category : Science
Languages : en
Pages : 306
Book Description
This book comprised of three separate volumes presents the recent developments and research discoveries in structural and solid mechanics; it is dedicated to Professor Isaac Elishakoff. This third volume is devoted to non-deterministic mechanics. Modern Trends in Structural and Solid Mechanics 3 has broad scope, covering topics such: design optimization under uncertainty, interval field approaches, convex analysis, quantum inspired topology optimization and stochastic dynamics. The book is illustrated by many applications in the field of aerospace engineering, mechanical engineering, civil engineering, biomedical engineering and automotive engineering. This book is intended for graduate students and researchers in the field of theoretical and applied mechanics.
Reinforced Concrete Structural Reliability
Author: Ph.D, Mohamed Abdallah El-Reedy
Publisher: CRC Press
ISBN: 1439874174
Category : Technology & Engineering
Languages : en
Pages : 369
Book Description
Structural engineers must focus on a structure's continued safety throughout its service life. Reinforced Concrete Structural Reliability covers the methods that enable engineers to keep structures reliable during all project phases, and presents a practical exploration of up-to-date techniques for predicting the lifetime of a structure. The book a
Publisher: CRC Press
ISBN: 1439874174
Category : Technology & Engineering
Languages : en
Pages : 369
Book Description
Structural engineers must focus on a structure's continued safety throughout its service life. Reinforced Concrete Structural Reliability covers the methods that enable engineers to keep structures reliable during all project phases, and presents a practical exploration of up-to-date techniques for predicting the lifetime of a structure. The book a
Reinforced Concrete Structural Reliability
Author: Mohamed Abdallah El-Reedy, Ph.D
Publisher: CRC Press
ISBN: 1439872031
Category : Technology & Engineering
Languages : en
Pages : 379
Book Description
Structural engineers must focus on a structure’s continued safety throughout its service life. Reinforced Concrete Structural Reliability covers the methods that enable engineers to keep structures reliable during all project phases, and presents a practical exploration of up-to-date techniques for predicting the lifetime of a structure. The book also helps readers understand where the safety factors used come from and addresses the problems that arise from deviation from these factors. It also examines the question of what code is best to follow for a specific project: the American code, the British Standard, the Eurocode, or other local codes. The author devotes an entire chapter to practical statistics methods and probability theory used in structural and civil engineering, both important for calculating the probability of structural failure (reliability analysis). The text addresses the effects of time, environmental conditions, and loads to assess consequences on older structures as well as to calculate the probability of failure. It also presents the effects of steel bar corrosion and column corrosion, and precautions to consider along with guides for design. This book offers guidelines and tools to evaluate existing as well as new structures, providing all available methods and tests for assessing structures, including visual inspection and nondestructive testing for concrete strength. It also presents techniques for predicting the remaining service life of a structure, which can be used to determine whether to perform repairs or take other action. This practical guide helps readers to differentiate between and understand the philosophy of the various codes and standards, enabling them to work anywhere in the world. It will aid engineers at all levels working on projects from the design to the maintenance phase, increasing their grasp of structure behavior, codes and factors, and predicting service life.
Publisher: CRC Press
ISBN: 1439872031
Category : Technology & Engineering
Languages : en
Pages : 379
Book Description
Structural engineers must focus on a structure’s continued safety throughout its service life. Reinforced Concrete Structural Reliability covers the methods that enable engineers to keep structures reliable during all project phases, and presents a practical exploration of up-to-date techniques for predicting the lifetime of a structure. The book also helps readers understand where the safety factors used come from and addresses the problems that arise from deviation from these factors. It also examines the question of what code is best to follow for a specific project: the American code, the British Standard, the Eurocode, or other local codes. The author devotes an entire chapter to practical statistics methods and probability theory used in structural and civil engineering, both important for calculating the probability of structural failure (reliability analysis). The text addresses the effects of time, environmental conditions, and loads to assess consequences on older structures as well as to calculate the probability of failure. It also presents the effects of steel bar corrosion and column corrosion, and precautions to consider along with guides for design. This book offers guidelines and tools to evaluate existing as well as new structures, providing all available methods and tests for assessing structures, including visual inspection and nondestructive testing for concrete strength. It also presents techniques for predicting the remaining service life of a structure, which can be used to determine whether to perform repairs or take other action. This practical guide helps readers to differentiate between and understand the philosophy of the various codes and standards, enabling them to work anywhere in the world. It will aid engineers at all levels working on projects from the design to the maintenance phase, increasing their grasp of structure behavior, codes and factors, and predicting service life.
Brick and Block Masonry
Author: Claudio Modena
Publisher: CRC Press
ISBN: 1315342669
Category : Technology & Engineering
Languages : en
Pages : 4087
Book Description
Brick and Block Masonry - Trends, Innovations and Challenges contains the lectures and regular papers presented at the 16th International Brick and Block Masonry Conference (Padova, Italy, 26-30 June 2016). The contributions cover major topics: - Analysis of masonry structures - Bond of composites to masonry - Building physics and durability - Case studies - Codes and standards - Conservation of historic buildings - Earthen constructions - Eco-materials and sustainability - Fire resistance, blasts, and impacts - Masonry bridges, arches and vaults - Masonry infill walls and RC frames - Masonry materials and testing - Masonry repair and strengthening - New construction techniques and technologies - Reinforced and confined masonry - Seismic performance and vulnerability assessment In an ever-changing world, in which innovations are rapidly implemented but soon surpassed, the challenge for masonry, the oldest and most traditional building material, is that it can address the increasingly pressing requirements of quality of living, safety, and sustainability. This abstracts volume and full paper USB device, focusing on challenges, innovations, trends and ideas related to masonry, in both research and building practice, will proof to be a valuable source of information for researchers and practitioners, masonry industries and building management authorities, construction professionals and educators.
Publisher: CRC Press
ISBN: 1315342669
Category : Technology & Engineering
Languages : en
Pages : 4087
Book Description
Brick and Block Masonry - Trends, Innovations and Challenges contains the lectures and regular papers presented at the 16th International Brick and Block Masonry Conference (Padova, Italy, 26-30 June 2016). The contributions cover major topics: - Analysis of masonry structures - Bond of composites to masonry - Building physics and durability - Case studies - Codes and standards - Conservation of historic buildings - Earthen constructions - Eco-materials and sustainability - Fire resistance, blasts, and impacts - Masonry bridges, arches and vaults - Masonry infill walls and RC frames - Masonry materials and testing - Masonry repair and strengthening - New construction techniques and technologies - Reinforced and confined masonry - Seismic performance and vulnerability assessment In an ever-changing world, in which innovations are rapidly implemented but soon surpassed, the challenge for masonry, the oldest and most traditional building material, is that it can address the increasingly pressing requirements of quality of living, safety, and sustainability. This abstracts volume and full paper USB device, focusing on challenges, innovations, trends and ideas related to masonry, in both research and building practice, will proof to be a valuable source of information for researchers and practitioners, masonry industries and building management authorities, construction professionals and educators.
Structural Design Optimization Considering Uncertainties
Author: Yannis Tsompanakis
Publisher: CRC Press
ISBN: 0203938526
Category : Technology & Engineering
Languages : en
Pages : 670
Book Description
Uncertainties play a dominant role in the design and optimization of structures and infrastructures. In optimum design of structural systems due to variations of the material, manufacturing variations, variations of the external loads and modelling uncertainty, the parameters of a structure, a structural system and its environment are not given, fi
Publisher: CRC Press
ISBN: 0203938526
Category : Technology & Engineering
Languages : en
Pages : 670
Book Description
Uncertainties play a dominant role in the design and optimization of structures and infrastructures. In optimum design of structural systems due to variations of the material, manufacturing variations, variations of the external loads and modelling uncertainty, the parameters of a structure, a structural system and its environment are not given, fi
Risk and Reliability in Structural Engineering
Author: Naiwei Lu
Publisher: Momentum Press
ISBN: 1947083376
Category : Technology & Engineering
Languages : en
Pages : 162
Book Description
The primary purpose of this book is to introduce risk and reliability concept into structural design. A structure should be designed taking into account safety, reliability, and economy. Reliability is the probability of successful function, and risk is the potential for unwanted negative consequence of an event. In structural engineering, risk analysis involves the investigation of the probability of rare events. Risk analyses are typically made on the basis of information, which is subject to uncertainty. These uncertainties may be divided into inherent or natural variability. The objective of a structural design is the assurance of successful performance over the useful life of structures or engineering systems. The primary purpose of this book is to introduce risk and reliability concept into structural design. It will cover and review reliability theory and risk analysis to solve structural engineering problems. The book was formed from the easy to the difficult and complicated concepts. Content was written from the basic concepts of uncertainties, structural safety analysis, structural reliability under repeated load, and fatigue reliability. Based on the introduction of failure modes and bounds theory, structural system reliability theory is subsequently discussed. Numerical formulation and examples are provided to enhance the study efficiency of students, engineers, and researchers. This book is suitable for adoption as a textbook or a reference book in a structural reliability analysis course. Furthermore, this book also provides a theoretical foundation for better understanding of the structural safety assessment.
Publisher: Momentum Press
ISBN: 1947083376
Category : Technology & Engineering
Languages : en
Pages : 162
Book Description
The primary purpose of this book is to introduce risk and reliability concept into structural design. A structure should be designed taking into account safety, reliability, and economy. Reliability is the probability of successful function, and risk is the potential for unwanted negative consequence of an event. In structural engineering, risk analysis involves the investigation of the probability of rare events. Risk analyses are typically made on the basis of information, which is subject to uncertainty. These uncertainties may be divided into inherent or natural variability. The objective of a structural design is the assurance of successful performance over the useful life of structures or engineering systems. The primary purpose of this book is to introduce risk and reliability concept into structural design. It will cover and review reliability theory and risk analysis to solve structural engineering problems. The book was formed from the easy to the difficult and complicated concepts. Content was written from the basic concepts of uncertainties, structural safety analysis, structural reliability under repeated load, and fatigue reliability. Based on the introduction of failure modes and bounds theory, structural system reliability theory is subsequently discussed. Numerical formulation and examples are provided to enhance the study efficiency of students, engineers, and researchers. This book is suitable for adoption as a textbook or a reference book in a structural reliability analysis course. Furthermore, this book also provides a theoretical foundation for better understanding of the structural safety assessment.