2,420 research outputs found
Development of a virtual reality milling machine for knowledge learning and skill training
No full textCurrent methods of training personnel on high cost machine tools involve the use of both classroom and hands on practical training. The practical training required the operation of costly equipment and the trainee has to be under close personnel supervision. The main aim of this project is to reduce the amount of practical training and its inherent cost, time, danger, personal injury risk and material requirements by utilising a virtual reality technology.
In this study, an investigation into the use of Virtual reality for training operators and students to use the Milling Machine was carried out. The investigation has been divided into two sections: first the development of Milling Machine in the 3D virtual environment, where the real machine was re-constructed in the virtual space.
This has been carried out by creating objects and assembling them together. The complete Milling machine was then properly modelled and rendered so it could be viewed from all viewpoints.
The second section was to add motion to the virtual world. The machine was made of functions as for the real machine. This was achieved by attaching Superscape Control Language (SCL) to the objects. The developed Milling machine allows the users to choose the material, speed and feed rate. Upon activation, the virtual machine will be simulated to carry out the machining process and instantaneous data on the machined part can be generated.
The results were satisfactory, the Milling Machine was modelled successfully and the machine was able to perform according to task set. Using the developed Virtual Model, the ability for training students and operators to use the Milling Machine has been achieved
Enantiopure Tetrathia[7]helicene-based Gold(I) Complexes
No full textTetrathia[7]helicenes (7-TH) are polyconjugated -systems in which four thiophene rings are orthofused to alternating arene rings to generate a non planar, chiral, stable helix which allows the existence of M and P enantiomers. The 7-TH systems are very interesting structures1 even because they can be easily and selectively functionalized in the alpha positions of the terminal thiophene rings,2 making it possible the introduction of appropriate substituents.
In the course of our studies on the synthesis of phosphane derivatives of 7-TH as potential innovative chiral ligands in asymmetric organometallic catalysis,3 gold(I) complexes of the phosphines of 7,8-di-n-propyl-tetrathia[7]helicene 1 and 2 (Figure 1) provided promising results in some cycloisomerization reactions.
Figure 1.
Encouraged by these results, the two P and M enantiomers of gold(I) complex 1 have been synthesized, and tested in asymmetric transformations.
The use of gold in homogeneous catalysis has witnessed tremendous activity in recent years.4 Thanks to gold(I) phosphine-based catalysts, various organic transformations have been accessible with both high yields and chemo- and stereoselectivity. In particular, asymmetric gold catalysis represents a very hot topic in catalytic research,5 and several efforts have been made by various research groups in this field.
References
1. Collins, S. K.; Vachon, M. P. Org. Biomol. Chem. 2006, 4, 2518-2524.
2. Licandro, E.; Baldoli, C.; Maiorana, S. et al. Synthesis 2006, 3670-3678.
3. Cauteruccio, S.; Licandro, E.; Maiorana, S. et al. Eur. J. Org. Chem. 2011, 5649-5658.
4. Hashmi, A. S. K.. Chem. Rev. 2007, 107, 3180-3211.
5. Sengupta, S.; Shi, X. ChemCatChem 2010, 2, 609-619
Miriam Sampaio : Murmur
No full textThis publication stems from artist Sampaio’s residency at Centre de production Daïmõn in the fall of 2001. The resulting exhibition comprised photographs taken by the artist while in Portugal where she was researching her Judaic-Portuguese roots. Hashmi comments on this work in a personal and poetic text that includes many quotes from the artist. Texts in English and French. Biographical notes on artist and author. 2 bibl. ref
Mechanical and metallurgical properties of two-layered diamalloy 4010 and 2002 HVOF coating
No full textDiamalloy 4010, which is iron/molybdenum blend, is resistive to wear and Diamalloy 2002 is resistive to corrosion and wear. However, combination of these powders in layered structure, may offer advantages over the individual powders. In this case, mechanical properties of the resulting layered structure could be improved. Consequently, investigation into mechanical and metallurgical properties of the resulting structure is necessary. High Velocity Oxy-Fuel coating of Diamalloy 2002 [(WC12Co)50,Ni33Cr9Fe3.5Si2B2C0.5] powders and Diamalloy 4010 [Fe68Mo30Cr1.8Mn0.2] powders as well as two-layered coatings consisting of these powders was carried out. In the two-layered structure, Diamalloy 4010 was sprayed at the substrate surface while Diamalloy 2002 was sprayed on the top of Diamalloy 4010 coating. The coating microstructure and morphology were examined using optical microscope, Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS). The indentation tests were carried out to evaluate the microhardness and surface elastic modulus of the resulting coatings. The mechanical properties of the coatings were examined through tensile and three-point bending tests. It was found that the coating produced for Diamalloy 2002 resulted in higher hardness than that corresponding to Diamalloy 4010. The failure mechanism of coating during tensile and three-point bending tests was mainly crack formation and propagation in the coating. The elastic modulus of coating produced from Diamalloy 2002 was higher than that of Diamalloy 4010 coating, which was due to the presence of 12% WC in the coating. The irregularities observed in the elastic limit of the curves indicated the formation of cracks in the coatings, which was particularly true for two layered coating. The shear stress developed at interface of the two-layered coating was responsible for the crack initiation in the coating. The deep cracks were also formed in the coatings after the tensile tests. This was attributed to the local stress centers, which increased the stress intensity under the tensile load
Investigation into coatings produced from nanoparticle blended feedstock for rotating equipment repair applications
No full textCoating of carbon steel with conventional and nano particle blended feedstock material is considered in relation to repair applications of rotating equipment. Gas Metal Arc Welding (GMAW) and Wire Arc Spray (WAS) processes are used to produce the coatings on carbon steel workpieces. The wire arc sprayed workpieces are heat treated at temperature similar to the operating temperature of hot-path components of power gas turbines. The microstructure and metallurgy of the workpieces are examined using the Scanning Electron Microscope (SEM), Optical Microscope, Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD). The indentation tests are carried out to assess the microhardness variation across the coatings. In the case of coatings produced by GMAW, it is found that fine structures are formed in the coating due to the presence of nano particles and they resulted in increased microhardness of the coatings. In the case of the wire arc sprayed workpieces, the formation of dimples like structure at the surface increases the surface roughness of the coatings. In addition, the microhardness of the resulting coating is significantly higher than that of the base material. The heat treatment does not alter the microstructure and microhardness of the coatings significantly
Bis[5-(4-methoxybenzyl)furan-3-yl]methanone
No full textThe title compound, C25H22O5, was obtained by a dehydrogenative carbonylation reaction. It crystallizes with one half-molecule in the asymmetric unit. The molecules have crystallographic C2 symmetry and the two atoms of the carbonyl group are located on the rotation axis. The methoxy groups are coplanar with the benzene ring to which they are attached [C-C-O-C = 1.0 (6)°]. The two furan rings are inclined at 17.3 (3)° with respect to each other and the dihedral angle between the furan ring and the benzene ring is 75.83 (12)°. The crystal structure is stabilized by C-H...O hydrogen bonds. Key indicators: single-crystal X-ray study; T = 183 K; mean ( σ(C–C) = 0.006 Å; R factor = 0.081; wR factor = 0.195; data-to-parameter ratio = 13.4
CCDC 2155479: Experimental Crystal Structure Determination
No full textRelated Article: Robin Heckershoff, Tobias Schnitzer, Tim Diederich, Lukas Eberle, Petra Krämer, Frank Rominger, Matthias Rudolph, A. Stephen K. Hashmi|2022|J.Am.Chem.Soc.|144|8306|doi:10.1021/jacs.2c0239
CCDC 2155478: Experimental Crystal Structure Determination
No full textRelated Article: Robin Heckershoff, Tobias Schnitzer, Tim Diederich, Lukas Eberle, Petra Krämer, Frank Rominger, Matthias Rudolph, A. Stephen K. Hashmi|2022|J.Am.Chem.Soc.|144|8306|doi:10.1021/jacs.2c0239
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