Practical Issues in the Application of Direct Metal Laser Sintering

Direct Metal Laser Sintering (DMLS) was introduced to meet the objective of producing metal parts directly from CAD data. CRDM has accumulated six years of experience in applying this technique, mostly to prototyping parts for evaluation. For some applications, such as blow moulds, porosity generated in DMLS has proved to be beneficial, but for others a concession on tolerances or finish are necessary and/or complementary operations are required, which add to manufacturing time and cost. This paper examines such issues through some well chosen examples of parts to demonstrate both the strengths and weaknesses of the DMLS process.Mechanical Engineerin

Pilot evaluation of sailplane handling qualities

The evaluation sailplanes were found generally deficient in the area of cockpit layout. The pilots indicated general dissatisfaction with high pitch sensitivity especially when coupled with inertially induced stick forces. While all sailplanes were judged satisfactory for centering thermals and in the ease of speed control in circling flight, pilot opinions diverged on the maneuvering response, pull-out characteristics from a dive, and on phugoid damping. Lateral-directional control problems were noted mainly during takeoff and landing for most sailplanes with the landing wheel ahead of center of gravity. Pilot opinion of in-flight lateral-directional stability and control was generally satisfactory. Five of the evaluation sailplanes exhibited a very narrow airspeed band in which perceptible stall warning buffet occurred. However, this characteristic was considered not objectionable when stall recovery was easy. The pilots objected to the characteristics of a wide airspeed band of stall warning followed by a stall with yawing and rolling tendency and substantial loss of altitude during the stall. Glide path control for the evaluation sailplanes was found to be generally objectionable

Constructing N-qubit entanglement monotones from anti-linear operators

We present a method to construct entanglement measures for pure states of multipartite qubit systems. The key element of our approach is an antilinear operator that we call {\em comb} in reference to the {\em hairy-ball theorem}. For qubits (or spin 1/2) the combs are automatically invariant under SL(2,\CC). This implies that the {\em filters} obtained from the combs are entanglement monotones by construction. We give alternative formulae for the concurrence and the 3-tangle as expectation values of certain antilinear operators. As an application we discuss inequivalent types of genuine four-qubit entanglement.Comment: 5 pages, revtex4; more detailed illustration of the metho

Entanglement entropy of multipartite pure states

Consider a system consisting of $n$ $d$-dimensional quantum particles and arbitrary pure state $\Psi$ of the whole system. Suppose we simultaneously perform complete von Neumann measurements on each particle. One can ask: what is the minimal possible value $S[\Psi]$ of the entropy of outcomes joint probability distribution? We show that $S[\Psi]$ coincides with entanglement entropy for bipartite states. We compute $S[\Psi]$ for two sample multipartite states: the hexacode state ($n=6, d=2$) and determinant states ($n=d$). The generalization of determinant states to the case $d<n$ is considered.Comment: 7 pages, REVTeX, corrected some typo

Privatisation Methods and Economic Growth in Transition Economies

In low-income countries privatization, if implemented appropriately, may play an important role in generating growth. Using data recently available from Central and Eastern Europe, we therefore investigate the impact of alternative methods of privatization on economic growth. Our analysis suggests that the use of conventional privatization methods to match owners with firms can be inefficient in economies with underdeveloped capital markets, particularly if wealth is poorly correlated with managerial and entrepreneurial ability. In these circumstances mass privatization, with firms being given away or sold at a nominal price, may be the appropriate policy choice

Valuing the Protection of Victorian Forests: Murray River Red Gums, and East Gippsland

The Victorian Environmental Assessment Council, in developing recommendations for the Victorian Government on the future management of public lands forests along he Murray River, and in East Gippsland, commissioned an analysis of environmental protections values. This paper reports the results of a choice modeling application that provides that analysis. Values for improved environmental conditions, as described by attributes relating to the forest composition, its wildlife characteristics and recreational opportunities, were estimated for sub-samples of households in Melbourne and in various regions around Victoria. The usefulness of the results as inputs to benefit cost analyses of policy alternatives is assessed.forests, Victoria, choice modeling, benefit cost analysis, Environmental Economics and Policy,

Marriage Patterns in the United States

This paper analyzes cohort marriage patterns in the United States in order to determine whether declining rates of first marriage are due to changes in the timing of marriage, the incidence of marriage, or both. Parametric models, which are well-suited to the analysis of censored or truncated data, are fit separately to information on age at first marriage derived from three data sets which were collected independently and at different points in time. Extended versions of the models are also estimated in which the parameters of the model distributions are allowed to depend on social and, economic variables.The results provide evidence that the incidence of first marriage is declining and that there is only a slight tendency for women to delay marriage. In addition, education is the most important correlate of decisions about the timing of first marriage whereas race is the most important correlate of decisions about its incidence.

Method for constructing periodic orbits in nonlinear dynamic systems

Method is modification of generalized Newton-Ralphson algorithm for analyzing two-point boundary problems. It constructs sequence of solutions that converge to precise dynamic solution in the sequence limit. Program calculates periodic orbits in either circular or elliptical restricted three-body problems