64,089 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
Shafiq Fatima Shera Urdu Nazm ki Munfarid Aawaz
No full text<p>Shafiq Fatima Shera is widely considered a 'difficult poet'. That is the reason she couldn't get the identity she deserves. This study will be able to present an in-depth analysis of Shera's thought process, the power of her language and imagery, and her sustained creativity. Shera's spiritual sustenance and psychic restorations will also be studied for determining her distinctiveness. Till date, there is not any specific book on Shera's contributions as a poet. She was praised by only some of the critics of her age. Though we have some important writings (of Fuzail Jafri, Waheed Akhtar, Hameed Nasim, and Mushaf Iqbal Tausifi) discussing one or other aspect of her poetry. Besides, two dissertations for M.Phil. on the topics شفیق فاطمہ شِعریٰ کا اردو کی جدید شاعری میں حصہ and شفیق فاطمہ شِعریٰ کے کلام میں تلمیحات were submitted at Osmania University, Hyderabad, and MANUU, Hyderabad respectively under the supervision of Prof. Baig Ehsas and Prof. Nasimuddin Farees in 2004 and 2009. Whereas an M. Phil. Dissertation on the topic شفیق فاطمہ شِعریٰ کی شاعری کا محاکمہ was completed under the guidance of Prof. Mazhar Mehdi Hussain at JNU, New Delhi in 2014. They are still unpublished. Shera's poetry has also been a part of a couple of theses written on Urdu poetry. In this analysis of Shera's long poem "Silsila-e-Mukalamaat", it is be argued that Shera has not imbued elements of religion as a fashion. Her poetry has the richest and most thoughtful blend of imagery and style. She overshadows her contemporaries in poetic style and imagination. This research will also construe that she was a far better and more promising poet than most of her male contemporaries.</p>
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
Bending analysis of switchable frequency selective surface based on flexible composite substrate
No full textIn this paper presents a switchable frequency selective surface (FSS) based on composite flexible substrate has been investigated. To make the FSS switchable, various combinations of switches are used. The design is bent E-field and H-field directions over various bending curvatures and the corresponding behavior is analyzed. It is observed that design has less variation when bending is applied along H-field direction. Whereas, slight variations are observed when bending is applied along the E-field direction. It is noted that the design exhibits stop band and pass band characteristics. Furthermore, in pass band it provides single wideband and dual band operations. These characteristics are preserved when bending is applied, thus making it suitable for wearable applications and modern communication systems
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
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Sidelobe Suppression in Resonant Cavity Antennas through Near-field Analysis
No full textThis paper describes an effective approach to reduce the high sidelobe levels (SLLs) in resonant cavity antennas (RCAs) with small footprints. The objective is to first understand the reason behind the high SLL in compact RCAs and than improve its radiation characteristics. For this, a near-field to far-field transformation routine is implemented in MATLAB, which allows to understand the individual effects of near-field amplitude and phase distributions on the SLL in the far-field patterns. This approach resulted in an optimal electric-field distribution, which is realized by a dielectric partially reflecting superstructure (PRS) exhibiting a broadside directivity of 19.5 dBi with significantly low sidelobe levels of -30dB in both the principle planes. It is important to note that the proposed approach can be linked easily with global optimization techniques to fit the radiation patterns within specific pattern masks
All-dielectric compact superstrates for high-gain resonant-cavity antennas: Designs & Measurements
No full textThis paper presents the designs and measurements of two compact single-layer all-dielectric resonant-cavity antennas (RCAs). Both the antennas are compact (footprint < 5.5λ20) and low in profile (overall height < 0.9λ0). The first RCA consists of a single-layer partially reflecting superstrate (PRS) in which thickness and permittivity vary from the center towards the edge of the PRS. Four commercially available dielectric materials are used to achieve this permittivity variation. This RCA demonstrates a measured peak directivity of 20.7 dBi and its 3dB directivity bandwidth extends from 12.75-19 GHz, which is 57% at the center frequency. The second RCA, made out of a single dielectric material demonstrates a measured peak directivity of 20.3 dBi and its measured 3dB directivity bandwidth is 55.9%. This class of compact single-layer RCAs, with a directivity bandwidth product per unit area (DBP/A) of greater than 1200, successfully overcomes the trade-off between directivity, bandwidth, profile and footprint and breaks the challenging barrier that has existed for RCAs over the last decade (and other planar high-gain antennas)
Stable voters in an unstable party environment : continuity and change in Italian electoral behaviour
No full textM.24981-1999 Paolo Segatti, Paolo Bellucci and Marco Maraffi. 30 cm. A previous version of this paper was presented at a symposium on Political Parties : Changing Roles in Contemporary Democracies, held at the Center for Advanced Study in the Social Sciences of the Juan March Institute, Madrid, December 15-17, 1994. -- P.1. Includes bibliographical references (p. 56-59
- …
