Author: Gabriela Goldschmidt and William L. Porter (Eds.) | Size: 5.5 MB | Format:PDF | Quality:Original preprint | Publisher: Springer | Year: 2004 | pages: 241 | ISBN: 1852337532
Preface
In April 1999, the undersigned co-chaired a meeting entitled “The 4th
International Design Thinking Research Symposium,” or DTRS ’99, at the
Massachusetts Institute of Technology (MIT). The theme of the symposium
was Design Representation. The present book has its roots in that event.
We have been interested in design representation for a long time, in ways
both similar and complementary. We have for years written and taught
courses that explored design representation, although we used other terms to
describe what we were looking at. We learned that other people, in various
design and design research domains, were showing increasing interest in
questions pertaining to representation. Therefore, we chose this theme as the
topic of the 4th Design Thinking Research Symposium when our good fortune
destined us to organize and chair it. The journey we have undertaken, starting
with the inception of the idea for the symposium, came to a conclusion
only once these pages were assembled. It was a true intellectual adventure
that we enjoyed tremendously, as it gave us an opportunity to learn more,
to ask many questions, and to create a fruitful dialogue with contributors to
this book. Although all the authors attended the DTRS meeting, and most of
the chapters in this book build on presentations made there, the book is
in no way a replication of the meeting’s proceedings.1 Nor does it resemble
two special issues of professional journals, guest-edited by us, that feature
DTRS’99 papers.2
Deciding on the precise focus, the structure and the layout of this book
was no easy task, even after many months of dealing with the topic. We
approached the job of editing this book like a design job and we allowed the
material to talk back to us. Our deepest appreciation is herewith extended to
the authors who shared their thinking with us, who responded to our questions,
who made fine suggestions, and who were very patient with us. We are
likewise extremely obliged to the entire Design Thinking Research community,
whose many members so enthusiastically responded to the idea of
holding the meeting in 1999. We believe that the clear voices of approval that
have come out of this community made it possible for us to target Design
Representation as the focal point of our work. We are indebted to the
Department of Architecture at MIT for the support – both intellectual and
material – that it has provided to the DTRS meeting and its preparation.
Major support from Autodesk, Inc., auto•des•sys, Inc., and the MicrosoftCorporation helped make for a richer event. A considerable number of MIT
students and employees worked hard to make it a successful experience.
Without the help of all of them, we would not have had the base that paved
the way for this book. Infinite gratitude goes to the Graham Foundation for
Advanced Studies in the Fine Arts, whose generous grant enabled us to bridge
the geographic distance that separates us and to collaborate on our project
in ways that would have not been possible otherwise. Finally, we are most
grateful to Pamela Siska for considerably uplifting the language and form of
our texts, and to Francesca Warren, our editor at Springer Verlag, whose
enthusiasm and faith in this endeavour were decisive in bringing it to fruition.
Gabriela Goldschmidt, Haifa
William L. Porter, Cambridge, Massachusetts
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Foreword
This 2001 edition of CIBSE Guide C contains significant changes from the previous 1986
edition. Although basic physical data does not change with time, the refinement of measurement
and calculation techniques means that even this basic data needs to be reviewed at
intervals. Additionally, revisions to practice in calculation methods, product selection and
usage led to a requirement for changes in the presentation of the data. Much of the data in
the 1986 edition actually dates from 1970 and was therefore ripe for review.
The changes made for the 2001 edition are summarised below:
Section 1: Properties of humid air. The data tables remain unchanged but the introduction
has been updated. A critique of the data has been published in Building Services
Engineering Research and Technology, to which interested readers are referred (reference 11
to section 1).
Section 2: Properties of water and steam. This section has been reviewed and found to
need no amendment.
Section 3: Heat transfer. This section has been completely rewritten. The theoretical
basis has been reviewed in the light of current knowledge and the calculation procedures
updated. Reference tables have been updated to reflect current practice and needs.
Section 4: Flow of fluids in pipes and ducts. This section has been completely rewritten.
Both calculation methods and reference tables have been updated. In particular, the
opportunity has been taken to replace the limited and oversimplified tables of resistance
coefficients with a more comprehensive and rigorous treatment.
Section 5: Fuels and combustion. This section has been reviewed and comprehensively
updated to take account of changes to fuels and fuel characteristics.
Section 6: Units, standard and mathematical data. This section has been reviewed and
updated. Some obsolete data has been deleted and some extra data added.
These changes have taken a significant amount of time and effort to complete and I would
like to express my thanks to the volunteer authors, contributors, reviewers and CIBSE
staff for their valuable contributions.
Finally, we hope that all users will find this Guide a useful and authoritative source of reference
and guidance.
Paul Compton
Chairman, CIBSE Guide C
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Within cognitive science, two approaches currently dominate the problem of modeling representations. The symbolic approach views cognition as computation involving symbolic manipulation. Connectionism, a special case of associationism, models associations using artificial neuron networks. Peter Gardenfors offers his theory of conceptual representations as a bridge between the symbolic and connectionist approaches.Symbolic representation is particularly weak at modeling concept learning, which is paramount for understanding many cognitive phenomena. Concept learning is closely tied to the notion of similarity, which is also poorly served by the symbolic approach. Gardenfors's theory of conceptual spaces presents a framework for representing information on the conceptual level. A conceptual space is built up from geometrical structures based on a number of quality dimensions. The main applications of the theory are on the constructive side of cognitive science: as a constructive model the theory can be applied to the development of artificial systems capable of solving cognitive tasks. Gardenfors also shows how conceptual spaces can serve as an explanatory framework for a number of empirical theories, in particular those concerning concept formation, induction, and semantics. His aim is to present a coherent research program that can be used as a basis for more detailed investigations.
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Review
"This is a fearless book that casts a wide net around key issues in cognitive science. It offers the kind of coherent, unified view that the field badly needs." - Steven Sloman, Associate Professor, Cognitive and Linguistic Sciences, Brown University" --This text refers to an out of print or unavailable edition of this title.
Review
"This is a fearless book that casts a wide net around key issues in cognitive science. It offers the kind of coherent, unified view that the field badly needs." - Steven Sloman, Associate Professor, Cognitive and Linguistic Sciences, Brown University"
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Progressive building collapse occurs when failure of a structural component leads to the failure and collapse of surrounding members, possibly promoting additional collapse. Global system collapse will occur if the damaged system is unable to reach a new static equilibrium configuration. The objective of this research is to identify and investigate important issues related to collapse of seismically designed steel building systems using multi-scale computational models. Coupled multi-scale finite element simulations are first carried out to investigate the collapse response of moment resisting steel frame sub-assemblages. Simulation results suggest that for collapse resistant construction, designers should strive to use a larger number of smaller beam members rather than concentrate resistance in a few larger members and should specify ASTM A-992 steel rather than specifying generic steels. Improved behavior can also be achieved by increasing the shear tab thickness or directly welding the beam web to the column. Using information gleaned from the sub-assemblage simulations, computationally efficient structural scale models for progressive collapse analysis of seismically designed steel frames systems are developed. The models are calibrated and utilized within the context of the alternate path method to study the collapse resistance of multistory steel moment and braced frame building systems. A new analysis technique termed "pushdown analysis" is proposed and used to investigate collapse modes, failure loads and robustness of seismically designed frames. The collapse and pushdown analyses show that systems designed for high seismic risk are less vulnerable to gravity-induced progressive collapse and more robust than those designed for moderate seismic risk. Motivated by a number of deficiencies in existing ductile fracture models for steel, a new micro-mechanical constitutive model is proposed. Damage mechanics principles are used and a scalar damage variable is introduced to represent micro-structural evolution related to micro-void nucleation, growth and coalescence during the ductile fracture process in steels. Numerical implementation and parametric studies are presented and discussed. Calibration and validation studies show that the proposed model can successfully represent ductile fracture of steels. Although the system studies in this dissertation focused primarily on in-plane collapse response, the models and simulation methodologies developed herein can be extended in future work to address the collapse resistance of three-dimensional models.
A progressive collapse is initiated as a result of local structural damage and develops into a failure that is disproportionate to the initiating local damage. Structural collapse can be initiated by many hazards such as earthquakes, fires, or terrorist attacks. On 9/11, the World Trade Center (WTC) towers failed because the terrorist attack led to progressive collapse. Earthquake is a low probability/high consequence event. Therefore, it is very important to analyze how a progressive collapse caused by a seismic hazard event can unfold. In this study, the progressive collapse of a 4-story steel frame structure is analyzed under earthquake. Using equivalent base shear and alternative path methods, the conditional failure probability of a specified member and the probability of progressive collapse are both determined. Combining those results with the hazard curve of the seismic event, the progressive collapse probability of the entire structure due to earthquake can be determined. The risk assessment concept is used to evaluate the risk of a steel structure under earthquake. Based on risk analysis, the optimum size of members is obtained by using optimization under uncertainty. In this study, the procedure of estimating the probability of progressive collapse of a structure under earthquake is established. Risk estimation helps structural designer to identify critical members which have a substantial effect on structural reliability. The results of the optimal seismic design show that the expected total cost is mostly affected by the dimensions of critical members and the location of the structure.
Author: LAWRENCE E. KINSLER-AUSTIN R. FREY-ALAN B. COPPENS-JAMES V. SANDERS | Size: 19.7 MB | Format:PDF | Quality:Scanner | Publisher: John Wiley & Sons, Inc. | Year: 2000 | pages: 567 | ISBN: ISBN-10: 0471847895 | ISBN-13: 978-0471847892
The classic acoustics reference! This widely-used book offers a clear treatment of the fundamental principles underlying the generation, transmission, and reception of acoustic waves and their application to numerous fields. The authors analyze the various types of vibration of solid bodies and the propagation of sound waves through fluid media.
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PREFACE
Credit for the longevity of this work belongs to the original two authors, Lawrence Kinsler and Austin Frey, both of whom have now passed away. When Austin entrusted us with the preparation of the third edition, our goal was to update the text while maintaining the spirit of the first two editions. The continued acceptance of this book in advanced undergraduate and introductory graduate courses suggests that this goal was met. For this fourth edition, we have continued this updating and have added new material. Considerable effort has been made to provide more homework problems. The total number has been increased from about 300 in the previous editions to over 700 in this edition. The availability of desktop computers now makes it possible for students to investigate many acoustic problems that were previously too tedious and time consuming for classroom use. Included in this category are investigations of the limits of validity of approximate solutions and numerically based studies of the effects of varying the various parameters in a problem. To take advantage of this new tool, we have added a great number of problems (usually marked with a suffix "c" )where the student may be expected to use or write computer programs. Any convenient programming language should work, but one with good graphing software will make things easier. Doing these problems should develop a greater appreciation of acoustics and its applications while also enhancing computer skills.
The following additional changes have been made in the fourth edition:
(1) As an organizational aid to the student, and to save instructors some time, equations, figures, tables, and homework problems are all now numbered by chapter and section. Although appearing somewhat more cumbersome, we believe the organizational advantages far outweigh the disadvantages.
(2) The discussion of transmitter and receiver sensitivity has been moved to Chapter 5 to facilitate early incorporation of microphones in any accompanying laboratory.
(3) The chapters on absorption and sources have been interchanged so that the discussion of beam patterns precedes the more sophisticated discussion of absorption effects.
(4) Derivations from the diffusion equation of the effects of thermal conductivity on the attenuation of waves in the free field and in pipes have been added to the chapter on absorption.
(5) The discussions of normal modes and waveguideshave been collected into a single chapter and have been expanded to include normal modes in cylindrical and spherical cavities and propagation in layers.
(6) Considerations of transient excitations and orthonormality have been enhanced.
(7) Two new chapters have been added to illustrate how the principles of acoustics can be applied to topics that are not normally covered in an undergraduate course. These chapters, on finite-amplitude acoustics and shock waves, are not meant to survey developments in these fields. They are intended to introduce the relevant underlying acoustic principles and to demonstratehow the fundamentals of acoustics can be extended to certain more complicated problems. We have selected these examples from our own areas of teaching and research.
(8) The appendixes have been enhanced to provide more information on physical constants, elementary transcendental functions (equations, tables, and figures), elements of thermodynamics, and elasticity and viscosity.
New materials are frequently at a somewhat more advanced level. As in the third edition, we have indicated with asterisks in the Contents those sections in each chapter that can be eliminated in a lower-level introductory course. Such a course can be based on the first five or six chapters with selected topics from the seventh and eighth. Beyond these, the remaining chapters are independent of each other (with only a couple of exceptions that can be dealt with quite easily), so that topics of interest can be chosen at will. With the advent of the handheld calculator, it was no longer necessary for textbooks to include tables for trigonometric, exponential, and logarithmic functions. While the availability of desktop calculators and current mathematical software makes it unnecessary to include tables of more complicated functions (Bessel functions, etc.), until handheld calculators have these functions programmed into them, tables are still useful. However, students are encouraged to use their desktop calculators to make fine-grained tables for the functions found in the appendixes. In addition, they will find it useful to create tables for such things as the shock parameters in Chapter 17.
Alan B. Coppens
Black Mountain, NC
James V. Sanders
Monterey, CA
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As a result of the increasing number of terrorist attacks registered against American facilities in the United States or abroad, United States government agencies continue to improve the design of their buildings to make them safer and less vulnerable to terrorist attacks. One of the factors typically considered in designing safer buildings and structures, is their ability to prevent total collapse after the loss of load-carrying components (Progressive Collapse) resulting from a terrorist attack. The consequences of not having a building capable of reducing the potential for progressive collapse could be catastrophic, as it was the case of the Oklahoma City bombing in 1995 where 42% of the Alfred P. Murrah Federal Building was destroyed by progressive collapse and only 4% by the explosion or blast. This attack claimed 168 lives and left over 800 injured. Over the last 10 years, two United States government agencies have developed guidelines for the design of their structures to resist progressive collapse: (1) The General Services Administration, "Progressive Collapse Analysis and Design Guidelines," (GSA Guidelines) and (2) The Department of Defense Unified Facilities Criteria 4-023-03 "Design of Buildings to Resist Progressive Collapse" (UFC 4-023-03). Within both approaches, the main direct design procedure is the Alternate Path (AP) method, in which a structure is analyzed for collapse potential after the removal of a column or section of wall. Different analytical procedures may be used, including Linear Static (LS), Nonlinear Static (NLS), and Nonlinear Dynamic (NLD). Typically, NLD procedures give better and more accurate results, but are more complicated and expensive. As a result, designers often choose static procedures, which tend to be simpler, requiring less labor. As progressive collapse is a dynamic and nonlinear event, the load cases for the static procedures require the use of factors to account for inertial and nonlinear effects, similar to the approach used in ASCE Standard 41 "Seismic Rehabilitation of Existing Buildings" (ASCE 41). A number of inconsistencies have been indentified in the way the existing guidelines applied dynamic and non-linear load factors to their static approaches. As part of an existing effort to update the existing guidelines, this study used SAP2000 to perform several AP analyses on a variety of Reinforced Concrete and Steel Moment Frame buildings to investigate the magnitude and variation of the dynamic and non-linear load increase factors. The study concluded that the factors in the existing guidelines tend to yield overly conservative results, which often translate into expensive design and retrofits. This study indentified new load increase factors and proposes a new approach to utilize these factors when performing AP analyses for Progressive Collapse.
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