다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

This paper presents control and coordination algorithms for groups of vehicles. The focus is on autonomous vehicle networks performing distributed sensing tasks where each vehicle plays the role of a mobile tunable sensor. The paper proposes gradient descent algorithms for a class of utility functions which encode optimal coverage and sensing policies. The resulting closed-loop behavior is adaptive, distributed, asynchronous, and verifiably correct.

Coverage control for mobile sensing networks

A review on the attention mechanism of deep learning

Thermal barrier systems have been the subject of vigorous research and development activities over the past few years, driven by the demands for enhanced reliability and substantially higher operating temperatures envisaged for the next generations of gas turbine engines. The menu of candidate materials and architectures has expanded considerably, including numerous concepts based on zirconia as well as radically different materials, multilayers and modulated distributions of porosity and chemical composition. Advances in deposition processes enable increased flexibility for tailoring composition and microstructure to local requirements within the coating system, e.g. for thermal insulation, control of interdiffusion, enhanced resistance against environmental degradation and condition monitoring. Many challenges remain but healthy and growing collaborations between the science and technology communities bode well for future progress in this area.

Emerging materials and processes for thermal barrier systems

Multi-objective meta-heuristics: An overview of the current state-of-the-art

http://spiral.imperial.ac.uk/bitstream/10044/1/55793/7/1-s2.0-S1877705817358435-main.pdf

An integrated method for net-shape manufacturing components combining 3D additive manufacturing and compressive forming processes

This paper provides a review of the methods developed over the years for reducing working forces for the precision metal forming processes. Precision forging normally involves completely, or near completely closed cavity dies with no or minimal draft, making features on the extremities difficult to fill and requiring high loads. Means to minimise load, in order to enhance tool life, or reduce press capacity are crucial to the success of precision forging processes. The main concentration of this study is on design features which can be incorporated in tooling and/or workpiece in order to assist in minimisation of forging load while achieving complete die filling. The load reduction methods are presented using examples mainly of precision gear forging, which is representative of the precision forging of other axisymmetric components with complex peripheral shape. The methods reviewed are divided into the categories of (i) billet design, (ii) tool design and (iii) process design. Their effects on forging load reduction for precision forging, along with the authors’ opinions as to the benefits, drawbacks and applicability of each, are presented.

/pdf/a-review-of-force-reduction-methods-in-precision-forging-29yshjq52f.pdf

A review of force reduction methods in precision forging axisymmetric shapes

Three-dimensional virtual grain structure generation with grain size control

Aiming at the lightweight of gears, this article presents the hot forging process of a bi-metal gear fabricated by two metals of steel (tooth ring material) and aluminum alloy (core material). The process was studied by the finite element (FE) simulation and forming experiment. The FE model of the bi-metal gear forging process was established based on the symmetry of the gear and the structure of forging die by using the software Deform-3D. The hot forging experiment of the bi-metal gear was carried out to verify the accuracy of the FE simulation by the comparison of the metal flow behavior. Metal flow of three stages, namely upsetting, gap and tooth filling, and corner filling was analyzed in the hot forging process. Effects of three aspects including the gap between the core and ring, the height difference between the core and ring, and the ring thickness on the metal flow and forming load were investigated. The results of numerical simulation showed that different gaps and different height differences between the core and ring influence the relative flow of two metals and different ring thicknesses significantly influence the structure of the bi-metal gear; large gap and small height difference between the core and ring and small ring thickness can reduce the forming load.

Jianguo Lin

Papers

An integrated method for net-shape manufacturing components combining 3D additive manufacturing and compressive forming processes

A review of force reduction methods in precision forging axisymmetric shapes

Three-dimensional virtual grain structure generation with grain size control

Investigation on metal flow and forming load of bi-metal gear hot forging process

Creep rupture of copper and aluminium alloy under combined loadings : experiments and their various descriptions