Tool positioning error (TPE) characterisation in milling

Where the geometrical features so permit, the {workpiece–work-holding fixture} assembly is generally considered to be infinitely rigid. The {tool–tool-holder–spindle} assembly and the machine axes are then deformed under the action of the cutting forces. This deformation leads to a positioning error of the tool in relation to the theoretical position. With the aim of taking this positioning error into account, the inaccuracies obtained during end milling and side milling were experimentally modelled from the cutting conditions used for a given machine/mill/material triplet (TriM). Our “Virtual Worker” then used these models to predict machining errors according to the type of machining and to compensate for them.     

Acetylxylan-pheophorbide-a nanoparticles designed for tumor-targeted photodynamic therapy

The poor solubility of most photosensitizers (PS) hampers their practical use as clinical agents. Conjugation of PS with water-soluble nanoparticles has been often used to bypass this hurdle. We describe in this study the extraction of glucuronoacetylxylan from chestnut sawdust, the hemisynthesis of pheophorbide-a (Pha) and its covalent attachment to xylan. The resulting conjugates (xyl-Pha) spontaneously form water-soluble spherical nanoparticles (xyl-Pha NPs) ranging between 100 and 250 nm in diameter. Assayed against the HT-29 colorectal cancer cell line, xyl-Pha NPs exhibited a dose-dependent phototoxicity only when irradiated with red light.     

Eddy Current Probe Parameters Identification Using a Genetic Algorithm and Simultaneous Perturbation Stochastic Approximation

This study tries to identify the coil parameters using numerical methods. The eddy current testing (ECT) is used for evaluation of a crack with the aid of numerical simulations by utilizing the identification of these parameters. In this study, a comparison of the performance of the GA and SPSA algorithms to identify the parameter values of the coil sensors are presented. So, the optimization probe geometry is introduced in the simulation with Three-dimensional finite element simulations (FLUX finite element code) were conducted to obtain eddy current signals resulting from a crack in a plate made of aluminium. The simulation results are compared with experimental measurements for the defect present in a plate.     

An optimization approach for the localization of defects in an inhomogeneous medium from acoustic far-field measurements at a fixed frequency

We are interested in the localization of defects in non-homogeneous non-absorbing media, with far-field measurements, generated by plane waves. We present here a way to handle the inhomogeneous background problem by the means of a constrained optimization approach; in the lines of the inf criterion from the factorization method for constant backgrounds. We show that both cost function and constraints present a simple form that is easy to compute. They can thus be treated by many well-known optimization methods, and we numerically illustrate four of them.     

A Highly Efficient Olefin Metathesis Process for the Synthesis of Terminal Alkenes from Fatty Acid Esters

Recently, considerable attention has been focused on the use of olefin metathesis to convert oleochemicals into value-added products such as the bifunctional molecule methyl 9-decenoate, but the implementation of this process has been hampered by low ethenolysis efficiencies. We report herein the use of alpha olefins as ethylene surrogates in cross metathesis reactions with methyl oleate and soybean oil fatty acid methyl esters (soy FAME) resulting in considerable increases in catalyst efficiencies in the production of this promising chemical product. Additional gains in efficiency were realized by using a peroxide-scavenging feedstock pretreatment.     

Fermented food products made with vegetable materials from tropical and warm countries: microbial and technological considerations

For many centuries, human beings have made fermented food, responding to the need to prolong the shelf life of perishable raw materials. Among the latter, vegetable materials come in diverse forms – roots, cereals, fruits, etc. – and vary from one location to another, especially if we study the products made in tropical and warm parts of the world. Humankind has explored many ways to ferment foods. This has led to the development of a number of different products characterised by original microbial communities, specific nutritional properties and typical sensory features. However, facing tremendous difficulties – sanitary preoccupations, nutritional needs and variability of organoleptic quality – scientists and food makers are now at a crossroads. One strategy would be to deduce which major traits should be optimised from a careful analysis of these products. The addition of selected starters may emerge from this as a good course of action. However, in this article, we consider that the use of traditional approaches – spontaneous fermentation and backslopping – is compatible with the search for higher quality in these products, on condition, though, that certain hygienic rules are respected and sufficient knowledge of microorganisms and raw materials is acquired.     

Pressureless sintered silicon carbide tailored with aluminium nitride sintering agent

This study reports the influence of aluminium nitride on the pressureless sintering of cubic phase silicon carbide nanoparticles (β-SiC). Pressureless sintering was achieved at 2000 °C for 5 min with the additions of boron carbide together with carbon of 1 wt% and 6 wt%, respectively, and a content of aluminium nitride between 0 and 10 wt%. Sintered samples present relative densities higher than 92%. The sintered microstructure was found to be greatly modified by the introduction of aluminium nitride, which reflects the influence of nitrogen on the β-SiC to α-SiC transformation. The toughness of sintered sample was not modified by AlN incorporation and is relatively low (around 2.5 MPa m^1/2). Materials exhibited transgranular fracture mode, indicating a strong bonding between SiC grains.     

面向重大社会事件的电力应急资源两阶段规划方法

重大社会事件融合了信息、物理、社会多元信息,增大了传统电力应急资源规划的难度和复杂度,为此,提出面向重大社会事件的电力应急资源两阶段规划方法。分析电力应急资源规划的信息、物理、社会耦合因素,引入负荷重要度来量化重大社会事件对应急资源规划的影响,给出整合应急服务点规划与应急资源配置的两阶段规划框架;建立考虑负荷重要度的停电风险量化指标,综合考虑负荷停电风险、服务点投资成本和应急服务时限约束,构建应急服务点多点多目标规划模型,并提出基于ε约束的多目标模型求解方法;考虑应急资源需求的不确定性,提出基于区间优化的应急资源优化配置模型,并将原区间优化模型转化为乐观优化问题和悲观优化问题进行求解。算例仿真结果验证了所提两阶段规划方法的有效性。