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

Construction of N = 2 Chiral Supergravity Compatible with the Reality Condition

We construct N = 2 chiral supergravity (SUGRA) which leads to Ashtekar's canonical formulation. The supersymmetry (SUSY) transformation parameters are not constrained at all and auxiliary fields are not required in contrast with the method of the two-form gravity. We also show that our formulation is compatible with the reality condition, and that its real section is reduced to the usual N = 2 SUGRA up to an imaginary boundary term.Comment: 16 pages, late

Tackling Anti-Social Behaviour: A Critical Review

Over the past decade, anti-social behaviour (henceforth referred to as ASB) has become a focus of much policy-making and debate within central and local government and the police. Clear definitions of ASB are lacking, but the term is usually understood to refer to relatively minor criminal activity and non-criminal ‘nuisance’ behaviour that affects the social and/or physical environment of public or semi-public places. The term ASB is frequently used synonymously with ‘disorder’, and is sometimes associated with the concept of ‘incivilities’. Policy-makers and strategists, at national and local levels alike, reiterate that problems of ASB can have a massively detrimental effect on neighbourhoods as a whole, and on the lives of individuals. Hence strenuous and wide-ranging efforts are being made to support, develop and implement schemes for tackling ASB – involving a variety of enforcement and preventive measures

Destroying black holes with test bodies

If a black hole can accrete a body whose spin or charge would send the black hole parameters over the extremal limit, then a naked singularity would presumably form, in violation of the cosmic censorship conjecture. We review some previous results on testing cosmic censorship in this way using the test body approximation, focusing mostly on the case of neutral black holes. Under certain conditions a black hole can indeed be over-spun or over-charged in this approximation, hence radiative and self-force effects must be taken into account to further test cosmic censorship.Comment: Contribution to the proceedings of the First Mediterranean Conference on Classical and Quantum Gravity (talk given by T. P. S.). Summarizes the results of Phys. Rev. Lett. 103, 141101 (2009), arXiv:0907.4146 [gr-qc] and considers further example

Work function determination of promising material for thermionic converters

The work done to fabricate Marchuk plasma discharge tubes for measurement of the cesiated emission of lanthanum hexaboride and thoriated tungsten electrodes is described. A photon counting pyrometer was completed and is to be calibrated with a gold standard

Application of active controls technology to aircraft bide smoothing systems

A critical review of past efforts in the design and testing of ride smoothing and gust alleviation systems is presented. Design trade offs involving sensor types, choice of feedback loops, human comfort, and aircraft handling-qualities criteria are discussed. Synthesis of a system designed to employ direct-lift and side-force producing surfaces is reported. Two STOL aircraft and an executive transport are considered. Theoretically predicted system performance is compared with hybrid simulation and flight test data. Pilot opinion rating, pilot workload, and passenger comfort rating data for the basic and augmented aircraft are included