"On the Minskyan Business Cycle"

The essential insight Minsky drew from Keynes was that optimistic expectations about the future create a margin, reflected in higher asset prices, which makes it possible for borrowers to access finance in the present. In other words, the capitalized expected future earnings work as the collateral against which firms can borrow in financial markets or from banks. But, then, the value of long-lived assets cannot be assessed on any firm basis, as they are highly sensitive to the degree of confidence that markets have about certain events and circumstances that will unfold in the future. This means that any sustained shortfall in economic performance in relation to the level of expectations that are already capitalized in asset prices may promote the view that asset prices are excessive. Once the view that asset prices are excessive takes hold in financial markets, higher asset prices cease to be a stimulant. Initially debt-led, the economy becomes debt-burdened. In this article, it is argued that Keynes's views on the alternation of the "bull" and "bear" sentiment and asset price speculation over the business cycle can explain two of Minsky's central propositions relative to business cycle turning points that have often been found less than fully persuasive: (1) that financial fragility increases gradually over the expansion, and, (2) that the interest rate sooner or later, increases setting off a downward spiral bringing the expansion to an end.

"Speculation, Liquidity Preference, and Monetary Circulation"

The sharp exchanges that Keynes had with some of his critics on the loanable funds theory made it harder to appreciate the degree to which his thought was continuous with the tradition of monetary analysis that emanates from Wicksell, of which Keynes's A Treatise on Money was a part. In the aftermath of the General Theory (GT), many of Keynes's insights in the Treatise were lost or abandoned because they no longer fit easily in the truncated theoretical structure he adopted in his latter work. A part of Keynes's analysis in the Treatise which emphasized the importance of financial conditions and asset prices in determining firms' investment decisions was later revived by Minsky, but another part, about the way self-sustained biases in asset price expectations in financial markets exerted their influence over the business cycle, was mainly forgotten. This paper highlights Keynes's early insights on asset price speculation and its link to monetary circulation, at the risk perhaps, of downplaying the importance of the GT.

"Asset Prices, Liquidity Preference, and the Business Cycle"

In his Treatise on Money, Keynes relied on two different premises to argue that the interest rate need not rise with rising levels of expenditure. One of these was the elasticity of the money supply, and the other was the interaction between financial and industrial circulation. A decrease (increase) in what Keynes called the bear position was similar in its impact to that of a policy-induced increase (decrease) in the money supply. In his General Theory, this second line of argument lost much of its force as it became reformulated under the rubric of Keynes's liquidity preference theory of interest. Assuming that the interest rate sets the return on capital, Keynes dismissed the effect of bull or bear sentiment in equity markets as a second-order complication that can be ignored in analyzing the equilibrium level of investment and output. The objective of this paper is to go back to this old theme from the Treatise and underscore its importance for the Keynesian theory of the business cycle.

"Is the Dollar at Risk?"

A massive fiscal stimulus and, until recently, aggressive monetary easing have been successful in raising bond and real estate prices to unprecedented levels, inducing a credit boom that has prevented private consumption from falling. While it might still be too early to say that it worked, the strategy has indeed, for the time being, prevented the U.S. economy from slipping into a severe depression after the collapse of the stock market at the turn of the millennium.

Analytical modeling of spindle-tool dynamics on machine tools using Timoshenko beam model and receptance coupling for the prediction of tool point FRF

Regenerative chatter is a well-known machining problem that results in unstable cutting process, poor surface quality and reduced material removal rate. This undesired self-excited vibration problem is one of the main obstacles in utilizing the total capacity of a machine tool in production. In order to obtain a chatter-free process on a machining center, stability diagrams can be used. Numerically or analytically, constructing the stability lobe diagram for a certain spindleholdertool combination implies knowing the system dynamics at the tool tip; i.e., the point frequency response function (FRF) that relates the dynamic displacement and force at that point. This study presents an analytical method that uses Timoshenko beam theory for calculating the tool point FRF of a given combination by using the receptance coupling and structural modication methods. The objective of the study is two fold. Firstly, it is aimed to develop a reliable mathematical model to predict tool point FRF in a machining center so that chatter stability analysis can be done, and secondly to make use of this model in studying the effects of individual bearing and contact parameters on tool point FRF so that better approaches can be found in predicting contact parameters from experimental measurements. The model can also be used to study the effects of several spindle, holder and tool parameters on chatter stability. In this paper, the mathematical model, as well as the details of obtaining the system component (spindle, holder and tool) dynamics and coupling them to obtain the tool point FRF are given. The model suggested is veried by comparing the natural frequencies of an example spindleholdertool assembly obtained from the model with those obtained from a nite element software

Effect analysis of bearing and interface dynamics on tool point FRF for chatter stability in machine tools by using a new analytical model for spindle-tool assemblies

Self-excited vibration of the tool, regenerative chatter, can be predicted and eliminated if the stability lobe diagram of the spindle–holder–tool assembly is known. Regardless of the approach being used, analytically or numerically, forming the stability lobe diagram of an assembly implies knowing the point frequency response function (FRF) in receptance form at the tool tip. In this paper, it is aimed to study the effects of spindle–holder and holder–tool interface dynamics, as well as the effects of individual bearings on the tool point FRF by using an analytical model recently developed by the authors for predicting the tool point FRF of spindle–holder–tool assemblies. It is observed that bearing dynamics control the rigid body modes of the assembly, whereas, spindle–holder interface dynamics mainly affects the first elastic mode, while holder–tool interface dynamics alters the second elastic mode. Individual bearing and interface translational stiffness and damping values control the natural frequency and the peak of their relevant modes, respectively. It is also observed that variations in the values of rotational contact parameters do not affect the resulting FRF considerably, from which it is concluded that rotational contact parameters of both interfaces are not as crucial as the translational ones and therefore average values can successfully be used to represent their effects. These observations are obtained for the bearing and interface parameters taken from recent literature, and will be valid for similar assemblies. Based on the effect analysis carried out, a systematic approach is suggested for identifying bearing and interface contact parameters from experimental measurements

Closed-Form Green's Function Representations in Cylindrically Stratified Media for Method of Moments Applications

Cataloged from PDF version of article.Closed-form Green's function (CFGF) representations for cylindrically stratified media, which can be used as the kernel of an electric field integral equation, are developed. The developed CFGF representations can safely be used in a method of moments solution procedure, as they are valid for almost all possible source and field points that lie on the same radial distance from the axis of the cylinder (such as the air-dielectric and dielectric-dielectric interfaces) including the axial line (ρ = ρ′ and φ = φ′), which has not been available before. In the course of obtaining these expressions, the conventional spectral domain Green's function representations are rewritten in a different form so that i) we can attack the axial line problem and ii) the method can handle electrically large cylinders. Available acceleration techniques that exist in the literature are implemented to perform the summation over the cylindrical eigenmodes efficiently. Lastly, the resulting expressions are transformed to the spatial domain using the discrete complex image method with the help of the generalized pencil of function method, where a modified two-level approach is used. Numerical results are presented in the form of mutual coupling between two current modes to assess the accuracy of the final spatial domain CFGF representations. © 2009 IEE

Examination of Existent Propagation Models Over Large Inhomogeneous Terrain Profiles Using Fast Integral Equation Solution

Cataloged from PDF version of article.The accuracyof most widelyused empirical models are investigated using the spectrallyaccelerated forward-backward (FBSA) method as a benchmark solution. First, FBSA results are obtained for propagation over large scale terrain profiles and compared with measurements to assess the accuracyof FBSA. Then, accuracyof some International Telecommunication Union (ITU) and Federal Communications Commission (FCC) propagation models are investigated. It has been observed that, for rural areas, the prediction of the most recent ITU recommended propagation model (Rec. 1546) deviates much more than older models do

Efficient Computation of Nonparaxial Surface Fields Excited on an Electrically Large Circular Cylinder with an Impedance Boundary Condition

Cataloged from PDF version of article.An alternative numerical approach is presented for the evaluation of the Fock-type integrals that exist in the uniform geometrical theory of diffraction (UTD)-based asymptotic solution for the nonparaxial surface fields excited by a magnetic or an electric source located on the surface of an electrically large circular cylinder with an impedance boundary condition (IBC). This alternative approach is based on performing numerical integration of the Fock-type integrals on a deformed path on which the integrands are nonoscillatory and rapidly decaying. Comparison of this approach with the previously developed one presented in [1], which is based on invoking the Cauchy’s residue theorem by finding the pole singularities numerically, reveals that the alternative approach is considerably more efficient