Active fixturing: literature review and future research directions

Fixtures are used to fixate, position and support workpieces and represent a crucial tool in manufacturing. Their performance determines the result of the whole manufacturing process of a product. There is a vast amount of research done on automatic fixture layout synthesis and optimisation and fixture design verification. Most of this work considers fixture mechanics to be static and the fixture elements to be passive. However, a new generation of fixtures has emerged that has actuated fixture elements for active control of the part–fixture system during manufacturing operations to increase the end product quality. This paper analyses the latest studies in the field of active fixture design and its relationship with flexible and reconfigurable fixturing systems. First, a brief introduction is given on the importance of research of fixturing systems. Secondly, the basics of workholding and fixture design are visited, after which the state-of-the-art in active fixturing and related concepts is presented. Fourthly, part–fixture dynamics and design strategies which take these into account are discussed. Fifthly, the control strategies used in active fixturing systems are examined. Finally, some final conclusions and prospective future research directions are presented

Convergent synthesis of new N -substituted 2-{[5-(1H -indol-3-ylmethyl)-1,3,4-oxadiazol-2-yl]sulfanyl}acetamides as suitable therapeutic agents

abstract A series of N-substituted 2-{[5-(1H-indol-3-ylmethyl)-1,3,4-oxadiazol-2-yl]sulfanyl}acetamides (8a-w) was synthesized in three steps. The first step involved the sequential conversion of 2-(1H-indol-3-yl)acetic acid (1) to ester (2) followed by hydrazide (3) formation and finally cyclization in the presence of CS2 and alcoholic KOH yielded 5-(1H-indole-3-yl-methyl)-1,3,4-oxadiazole-2-thiol (4). In the second step, aryl/aralkyl amines (5a-w) were reacted with 2-bromoacetyl bromide (6) in basic medium to yield 2-bromo-N-substituted acetamides (7a-w). In the third step, these electrophiles (7a-w) were reacted with 4 to afford the target compounds (8a-w). Structural elucidation of all the synthesized derivatives was done by 1H-NMR, IR and EI-MS spectral techniques. Moreover, they were screened for antibacterial and hemolytic activity. Enzyme inhibition activity was well supported by molecular docking results, for example, compound 8q exhibited better inhibitory potential against α-glucosidase, while 8g and 8b exhibited comparatively better inhibition against butyrylcholinesterase and lipoxygenase, respectively. Similarly, compounds 8b and 8c showed very good antibacterial activity against Salmonella typhi, which was very close to that of ciprofloxacin, a standard antibiotic used in this study. 8c and 8l also showed very good antibacterial activity against Staphylococcus aureus as well. Almost all compounds showed very slight hemolytic activity, where 8p exhibited the least. Therefore, the molecules synthesized may have utility as suitable therapeutic agents

Nonlinear double-integral observer and application to quadrotor aircraft

10.1109/TIE.2014.2341571IEEE Transactions on Industrial Electronics6221189-120

Assembly modelling through constraint-based manipulations in a virtual reality environment

With today’s irtual reality (VR) systems, it is difficult to create precise assembly models through 3D interactions due to hardware limitations. In this paper, an efficient approach is presented for intuitive and precise assembly modeling in a VR environment. Assembly modelling is performed by precise constraint-based 3D direct manipulations in an intuitive manner. Constraint-based manipulations are accompanied with automatic constraint recognition and precise constraint satisfaction, and are realized by allowable motions for precise 3D interactions in the VR environment. Some special constraint-based assembly operations are constructed for assembly modelling in the VR environment. A method for recognizing the pairs of mating features between assembly components is presented. This method integrates 3D direct manipulations with a feature mating knowledge base and makes the process of recognizing a pair of mating features intuitive. A concept of offset solid is also presented for determining assembly components. A prototype system has been developed for assembly modelling through precise constraint-based manipulations in an intuitive manner in the VR environment

Synthesis and in vitro antioxidant activity studies of melatonin analogue compounds

52nd Congress of the European-Societies-of-Toxicology (EUROTOX) -- SEP 04-07, 2016 -- Seville, SPAINWOS: 000402436700604European Soc ToxicolScientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109S099]This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) Grant 109S099

A hybrid contact state analysis methodology for robotic-based adjustment of cylindrical pair

The peg-in-hole insertion and adjustment operation is one of the most common tasks in the robotic and automatic assembly processes. Fine motion strategies associated with adjustment operations on a peg-in-hole are fundamental manipulations that can be utilised in dynamic assembly and reconfigurable workholding or fixturing systems. This paper presents a comprehensive study of robotic-based height adjustment of a cylindrical pair based on maintaining minimum contact forces between the links