Optimization of Supports in Metal-Based Additive Manufacturing by Means of Finite Element Models

Metal-based additive manufacturing processes require a supporting of overhanging part areas during the powder solidification e. g. for improving the heat dissipation to the substrate. Technology users nowadays strive to reduce support areas due to economical aspects, while simultaneously enhancing the process stability by maximizing the support stiffness. For the simplification and acceleration of this support design procedure, the presented work describes a methodology for optimizing support structures by means of finite element models. Thereby, the main approaches are covering a fractal adaptation of the support layout and an optimization of block supports depending on the calculation results. The presented methods were applied by using experimental components.Mechanical Engineerin

G66-29

Onderzoeksrappor

Characteristics of post-transcriptional gene silencing

A number of gene silencing phenomena that inactivate genes at the post-transcriptional level have been identified. Due to its potential for studying gene function, post-transcriptional gene silencing (PTGS) has become an intense area of research. In this review we describe the different means of inducing PTGS and discuss the possible biological roles of these artificially induced phenomena. We also discuss other features of PTGS such as the mechanism of mRNA degradation, the nature of the silencing signal and the mechanism of PTGS inhibition by viral proteins

Photocatalytic hydrogenation of acetophenone on a titanium dioxide cellulose film

A previously developed sustainable immobilization concept for photocatalysts based on cellulose as a renewable support material was applied for the photocatalytic hydrogenation of acetophenone ACP to 1 phenyl ethanol PE . Four different TiO2 modifications P25, P90, PC105, and PC500 were screened for the reaction showing good performance for PC25 and PC500. PC500 was selected for a detailed kinetic study to find the optimal operating conditions, and to obtain a better understanding of the photocatalytic pathway in relation to conventional and transfer hydrogenation. The kinetic data were analyzed using the pseudo first order reaction rate law. A complete conversion was obtained for ACP concentrations below 1 mM using a 360 nm filter and argon as the purge gas within 2 3 hours. High oxygen concentrations slow down or prevent the reaction, and wavelengths below 300 nm lead to side products. By investigating the temperature dependency, an activation energy of 22 kJ mol amp; 8722;1 was determined which is lower than the activation energies for conventional and transfer hydrogenation, because the light activation of the photocatalyst turns the endothermic to an exothermic reaction. PC500 was immobilized onto the cellulose film showing a 37 lower activity that remains almost constant after multiple us

Design metalcutting instruments by dint of system of KOMPAS

Навчальний посібник містить відомості про методику й алгоритми проектування дискових зуборізних фрез, зуборізних довбачів і черв'ячних зуборізних фрез, призначених для нарізування різних типів зубчастих коліс. Використані основні аналітичні співвідношення для визначення конструктивних параметрів зазначених інструментів відповідно до розмірів і формою як корегованих, так і некорегованих зубчастих коліс. На базі спеціалізованого додатка «САПР ФРЕЗ» системи КОМПАС-3D виконується автоматизоване проектування зуборізного інструмента. Наведено методику побудови параметричних моделей евольвентного профілю, перехідної кривої та затилованого зуба.Учебное пособие содержит сведения о методике и алгоритмах проектирования дисковых зуборезных фрез, зуборезных долбяков и червячных зуборезных фрез, предназначенных для нарезания различных типов зубчатых колес. Использованы основные аналитические соотношения для определения конструктивных параметров указанных инструментов в соответствии с размерами и формой как коррегированных, так и некоррегированных зубчатых колес. На базе специализированного приложения «САПР ФРЕЗ» системы КОМПАС-3D выполняется автоматизированное проектирование зуборезного инструмента. Приведена методика построения параметрических моделей эвольвентного профиля, переходной кривой и затылованного зуба.The manual contains information about the methods and algorithms of designing gear cutting disc cutters, gear cutting cutters and worm gear shaping cutters designed for cutting various types of gears. Basic analytical equations to determine the design parameters of these instruments in accordance with the size and shape as the corrected and uncorrected gears are used. On the basis of specialized application "CAD MILLING CUTTERS» KOMPAS-3D system is carried out computer-aided design gear-cutting tool. The technique of building parametric models of involute profile, the transition curve and the relief of the tooth are represented

Kinetic investigation of para-nitrophenol reduction with photodeposited platinum nanoparticles onto tunicate cellulose

Photodeposition is a specific method for depositing metallic co-catalysts onto photocatalysts and was applied for immobilizing platinum nanoparticles onto cellulose, a photocatalytically inactive biopolymer. The obtained Pt@cellulose catalysts show narrow and well-dispersed nanoparticles with average sizes between 2 and 5 nm, whereby loading, size and distribution depend on the preparation conditions. The catalysts were investigated for the hydrogenation of para-nitrophenol via transfer hydrogenation using sodium borohydride as the hydrogen source, and the reaction rate constant was determined using the pseudo-first-order reaction rate law. The Pt@cellulose catalysts are catalytically active with rate constant values k from 0.09 × 10−3 to 0.43 × 10−3 min−1, which were higher than the rate constant of a commercial Pt@Al2O3 catalyst (k = 0.09 × 10−3 min−1). Additionally, the Pt@cellulose catalyst can be used for electrochemical hydrogenation of para-nitrophenol where the hydrogen is electrocatalytically formed. The electrochemical hydrogenation is faster compared to the transfer hydrogenation (k = 0.11 min−1)

Resistance Reduction Adsorption Filters Of Ventilation Systems

Предложены технические решения по снижению аэродинамического сопротивления проточной части угольных адсорберов вентиляционных системЗдійснено постановку та вирішення задачі оптимізації режимів різання при формуванні структури технологічної операції з однопрохідної обробкою на прикладі чорнового точіння. Виконано пошук глобального мінімуму цільової функціїTechnical solutions to reduce the aerodynamic resistance for a flowing part of a coal adsorber of ventilation systems are offere