Firdaus E. Udwadia

Bio: Firdaus E. Udwadia is an academic researcher from University of Southern California. The author has contributed to research in topics: Nonlinear system & Equations of motion. The author has an hindex of 41, co-authored 225 publications receiving 6212 citations. Previous affiliations of Firdaus E. Udwadia include California Institute of Technology.

Analytical Dynamics: A New Approach

Abstract: Preface 1 Introduction 2 Matrix algebra 3 The fundamental equation 4 Further applications 5 Elements of Lagrangian mechanics 6 The fundamental equation in generalized coordinates 7 Gauss's principle revisited 8 Connections among different approaches References Afterword Index

A New Perspective on Constrained Motion

Abstract: The explicit general equations of motion for constrained discrete dynamical systems are obtained. These new equations lead to a simple and new fundamental view of lagrangian mechanics.

Dynamics and Control

Abstract: 1. Control Methodology 2. Dynamical Systems 3. Applications to Social and Environmental Problems

Methodology for Optimum Sensor Locations for Parameter Identification in Dynamic Systems

Abstract: This paper provides a methodology for optimally locating sensors in a dynamic system so that data acquired from those locations will yield the best identification of the parameters to be identified. It addresses the following questions: (1) Given m sensors, where should they be placed in a spatially distributed dynamic system so that data from those locations will yield best estimates of the parameters that need to be identified?; and (2) given that we have already installed p sensors in a dynamic system, where should the next s be located? The methodology is rigorously founded on the Fisher information matrix and is applicable to both linear and nonlinear systems. A rapid algorithm is provided for use in large multi‐degree‐of‐freedom systems. After developing the general methodology, the paper goes on to develop the method in detail for a linear N‐degree‐of‐freedom, classically damped, system. Numerical examples are provided and it is verified that the optimal placement of sensors, as dictated by the met...

Effective Crisis Management

Abstract: M anagers, consultants, and researchers have traditionally focused on problems of financial performance and growth, but have paid little heed to the effective management of corporate crises. The negative effects of organizational and industrial activities have been treated as minor "externalities" of production. It can be argued that until recently, it was unnecessary to focus on such crises. Today, however, such crises as pollution, industrial accidents, and product defects have assumed greater magnitude. The consequences for many corporations-like Johns-Manville and A. H. Robins-have been near or actual bankruptcy. Corporate crises are disasters precipitated by people, organizational structures, economics, and/or technology that cause extensive damage to human life and natural and social environments. They inevitably debilitate both the financial structure and the reputation of a large organization. Consider the following examples: * In 1979, the Three Mile Island Nuclear Power Plant had an accident leading to the near meltdown of the plant's reactor core. The accident not only cost Metropolitan Edison-the company that owned the plantbillions of dollars; it altered the fate of the nuclear power industry in the United States.' The plant owners and operators paid $26 million in evacuation costs, financial losses, and medical surveillance; the estimated cost of repairs and the production of electricity via other means was $4 billion. * In 1982 an unknown person or persons contaminated dozens of Tylenol capsules with cyanide, causing the deaths of eight people and a loss of $100 million in recalled packages for Johnson & Johnson. In 1986 a second poisoning incident forced JJ compensation settlement is likely to be between $500 million and $1 billion. In addition, the company was forced to sell 20% of its most profitable assets to prevent a takeover attack mounted by GAF Corporation, which had acquired Carbide's undervalued stock after the accident.2 * In May and June 1985 deadly bacteria in Jalisco cheese caused the deaths of 84 people. The company that produced the product was forced into bankruptcy. The list of recent corporate disasters is virtually unending. It includes executive kidnappings; hijackings, both in the air and at sea; hostile takeovers; and such acts of terrorism as the bombing of factories and warehouses. Most recently, slivers of glass have been found in Gerber's baby food. Contac-an over-thecounter cold remedy-has also been the object of product tampering. Such incidents now happen on an ever-increasing basis. Further, the interval between major accidents is shrinking alarmingly.3 The number of product-injury lawsuits terminating in million-dollar awards has increased dramatically in the past decade: In 1974 fewer than 2,000 product injury lawsuits were filed in U.S. courts; by 1984, the number had jumped to 10,000. In 1975, juries had awarded fewer than 50 compensation awards of greater than $1 million each; in 1985, there were more than 400 such awards. The costs of productand production-related injury is one factor in the current liability insurance crisis. Many forms of liability insurance have simply vanished, and all forms of liability insurance have become so expensive, they are available only for small coverages. The purpose of this article is to argue that while the situation is grave, it is far from hopeless for managers, researchers, and consultants who are prepared to confront the problem directly. While no one can prevent all disasters-let alone predict how, when, and where they will occur-organizations can adopt a systematic and comprehensive perspective for managing them more effectively. Anything less than such a perspective virtually guarantees that an organization will be less than prepared to cope and recover effectively from a crisis.

New Empirical Relationships among Magnitude, Rupture Length, Rupture Width, Rupture Area, and Surface Displacement

Abstract: Source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude ( M ), surface rupture length, subsurface rupture length, downdip rupture width, rupture area, and maximum and average displacement per event. The resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment, moment magnitude, subsurface rupture length, downdip rupture width, and average surface displacement. Each source parameter is classified as reliable or unreliable, based on our evaluation of the accuracy of individual values. Only the reliable source parameters are used in the final analyses. In comparing source parameters, we note the following trends: (1) Generally, the length of rupture at the surface is equal to 75% of the subsurface rupture length; however, the ratio of surface rupture length to subsurface rupture length increases with magnitude; (2) the average surface displacement per event is about one-half the maximum surface displacement per event; and (3) the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement. Thus, for most earthquakes in this data base, slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface. Log-linear regressions between earthquake magnitude and surface rupture length, subsurface rupture length, and rupture area are especially well correlated, showing standard deviations of 0.25 to 0.35 magnitude units. Most relationships are not statistically different (at a 95% significance level) as a function of the style of faulting: thus, we consider the regressions for all slip types to be appropriate for most applications. Regressions between magnitude and displacement, magnitude and rupture width, and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area. The large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data. Separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions. Regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults, and to estimate the expected surface displacement along a fault for a given size earthquake.

Neuroscience 細胞死：最近の知見

Abstract: 中枢神経系疾患の治療は正常細胞（ニューロン）の機能維持を目的とするが，脳血管障害のように機能障害の原因が細胞の死滅に基づくことは多い．一方，脳腫瘍の治療においては薬物療法や放射線療法といった腫瘍細胞の死滅を目標とするものが大きな位置を占める．いずれの場合にも，細胞死の機序を理解することは各種病態や治療法の理解のうえで重要である．現在のところ最も研究の進んでいる細胞死の型はアポトーシスである．そのなかで重要な位置を占めるミトコンドリアにおける反応および抗アポトーシス因子について概要を紹介する．

Theoretical basis of some empirical relations in seismology

Abstract: Empirical relations involving seismic moment M_o, magnitude M_S, energy E_S and fault dimension L (or area S) are discussed on the basis of an extensive set of earthquake data (M_S ≧ 6) and simple crack and dynamic dislocation models. The relation between log S and log M_o is remarkably linear (slope ∼ 2/3) indicating a constant stress drop Δσ; Δσ = 30, 100 and 60 bars are obtained for inter-plate, intra-plate and “average” earthquakes, respectively. Except for very large earthquakes, the relation M_S ∼ (2/3) log M_o ∼ 2 log L is established by the data. This is consistent with the dynamic dislocation model for point dislocation rise times and rupture times of most earthquakes. For very large earthquakes M_S ∼ (1/3) log M_o ∼ log L ∼ (1/3) log E_S. For very small earthquakes M_S ∼ log M_o ∼ 3 log L ∼ log E_S. Scaling rules are assumed and justified. This model predicts log E_S ∼ 1.5 M_S ∼ 3 log L which is consistent with the Gutenberg-Richter relation. Since the static energy is proportional to σL^3, where σ is the average stress, this relation suggests a constant apparent stress ησ where η is the efficiency. The earthquake data suggest ησ ~ 1/2 Δσ. These relations lead to log S ∼ M_S consistent with the empirical relation. This relation together with a simple geometrical argument explains the magnitude-frequency relation log N ∼ − M_S.

Handbook of Chemistry and Physics

Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate