15,501 research outputs found
Visualisation of an entangled channel spin-1 system
Co-variance matrix formalism gives powerful entanglement criteria for
continuous as well as finite dimensional systems. We use this formalism to
study a mixed channel spin-1 system which is well known in nuclear reactions. A
spin-j state can be visualized as being made up of 2j spinors which are
represented by a constellation of 2j points on a Bloch sphere using Majorana
construction. We extend this formalism to visualize an entangled mixed spin-1
system.Comment: 4 pages,4 figure
Remote surface inspection system
This paper reports on an on-going research and development effort in remote surface inspection of space platforms such as the Space Station Freedom (SSF). It describes the space environment and identifies the types of damage for which to search. This paper provides an overview of the Remote Surface Inspection System that was developed to conduct proof-of-concept demonstrations and to perform experiments in a laboratory environment. Specifically, the paper describes three technology areas: (1) manipulator control for sensor placement; (2) automated non-contact inspection to detect and classify flaws; and (3) an operator interface to command the system interactively and receive raw or processed sensor data. Initial findings for the automated and human visual inspection tests are reported
Pb(Ni1/3Sb2/3)O3-PbZrTiO3 Ceramic Sensors for Underwater Transducer Application
Cymbal is a class-V flextensional transducer that consists of thickness poled ceramic disc sandwiched between the two metal end caps which acts as a mechanical transformer. Cymbal transducers were fabricated using piezoceramic discs of compositions Pb0.988(Zr0.52Ti0.48) 0.976Nb0.024O3 (PZT type 5A) and Pb0.98La0.02 (NiSb)0.05[(Zr0.52 Ti0.48)0.995]0.95O3 (PNS-PZT). Piezoelectric and hydrostatic constants for PNS-PZT composition were on higher side. End capswere made up of brass sheet having thickness 0.5 mm. Underwater testing of the polyurethane moulded cymbal hydrophones were carried out in acoustic tank and compared. The resonance frequency for both the hydrophones was 10.1 kHz. PNS-PZT hydrophone shows higher sensitivity (-183.2 dB re 1V/μPa) compared to PZT type 5A (-191.2 dB re 1V/μPa) at resonance frequency. Directivity pattern observed for PNS-PZT is omni-directional near resonance frequency.Defence Science Journal, 2012, 62(4), pp.269-273, DOI:http://dx.doi.org/10.14429/dsj.62.171
Utilisation of Iron Oxide Waste through Cold Bonded Pelletisaion
India is endowed with large reserves of iron ore. Mech-anised mining generates considerable amount of iron ore fines. Additionally, large quantities of slimes are generated from washing of ores at mine-heads.Further, many coal based rotary kiln sponge iron plants are generating
huge quantities waste fines within their works. In addi-tion, in integrated steel plants, a lot of iron oxide
rich wastes are generated. Some of them are generated mixed with carbon particles or hydrocarbons (oil, etc.).
All these pose problems both with respect to economy and ecology.
In RDCIS, work was carried out to pelletise iron ore fines after mixing with up to 10% non-coking coal, and utilise these composite pellets in coal based rotary kiln DR plants. These pellets were cold bonded so that carbon is retained for- reduction purpose. After extensive laboratory investigations, these pellets were tested in a rotary kiln DR plant.Composite pellets reduced much faster as compared to lump ore.Metallisation level of over 90% was achieved consistently. Kiln productivity increased and energy consumption decreased substantially.The plant trials established the suitability of composite pellets for DRI production in rotary kilns
Fracture Simulation of Concrete Beams to assess softening behavior by varying different fractions of Aggregates
Simulating the concrete fracture unlike other elastic and brittle materials quite different due to its quasibrittleness. The present research focussed on assess softening behavior by varying different fractions of aggregates and cement matrix in micro details. Extended Finite Element Method (XFEM) for crack modeling implemented for simulating and visualizing crack propagation through Cement matrix, Interfacial Transition Zone (ITZ) and Aggregates . This approach permits the initializing crack by from enrichment zone and propagation of crack through element by traction separation law .The crack formation initiates when the maximum principal tensile stress reaches the tensile strength.
The work involves creating python script for iterative process of random distribution of aggregates with in the matrix using Monte Carlo method and creating Cohesive zone element for zero thickness ITZ. introduces a finite element modeling technique for investigating multiscale fracture characteristics. This approach encompasses multiple levels of analysis, including the generation of aggregate particles using a Monte Carlo method implemented via a Python script. Additionally, we replicate the Interfacial Transition Zone (ITZ) between aggregate and mortar in the model. The load-deflection curves can be used to assess the softening behavior of concrete and suggest the realistic fraction of coarse aggregate in mix proportion to impart more ductility to beams
Self-dual Maxwell Chern-Simons Solitons In 1+1 Dimensions
We study the domain wall soliton solutions in the relativistic self-dual
Maxwell Chern-Simons model in 1+1 dimensions obtained by the dimensional
reduction of the 2+1 model. Both topological and nontopological self-dual
solutions are found in this case. A la BPS dyons here the Bogomol'ny bound on
the energy is expressed in terms of two conserved quantities. We discuss the
underlying supersymmetry. Nonrelativistic limit of this model is also
considered and static, nonrelativistic self-dual soliton solutions are
obtained.Comment: 18 pages RevTex, 2 figures included, to appear in Phys. Rev.
Numerical modelling of dissipation energy of high tensile steel frames against cyclic earthquake excitations
The design of steel structures for ductile response requires (a) materialductility, (b) cross section and member ductility, and (c) structural ductility. Dissipating the earthquake input energy by means of plastic excursions has to be compatible with the
plastic deformation capacity of the structure. This work concerns incremental approach of modeling for elastoplastic analysis of structural members subjected to harmonically varying severe earthquake loads and their parametric responses over a range of applied frequencies and amplitudes. Investigations have been carried out in respect of stable and reliable hysteretic energy dissipation mechanisms of high rise steel structures against typical time-history loading of four hypothetical frequencies. Eigen-buckling responses for high rise steel structures subjected to earthquake forces are derived using general purpose software (STAAD). Finally critical structural component is identified for the high rise steel structure for estimation of available in-elastic dissipation energy from material ductility against earthquake excitations. The novelty allows for a very useful generalized formulation for the basic analysis procedures adopted in non-linear material problems. All essential features of a non-linear finite element solution are described in relation to one dimensional model for elasto-plastic beam bending. Solutions techniques are programmed in FORTRAN 90 for Newton-Raphson iteration for non-linear finite element analysis to derive hysteretic energy dissipation of high rise steel structures
Accuracy of impressions with different impression materials in angulated implants
Purpose: To evaluate the dimensional accuracy of the resultant (duplicative) casts made from two different impression materials (polyvinyl siloxane and polyether) in parallel and angulated implants.Materials and Methods: Three definitive master casts (control groups) were fabricated in dental stone with three implants, placed at equi-distance. In first group (control), all three implants were placed parallel to each other and perpendicular to the plane of the cast. In the second and third group (control), all three implants were placed at 10° and 15° angulation respectively to the long axis of the cast, tilting towards the centre. Impressions were made with polyvinyl siloxane and polyether impression materials in a special tray, using a open tray impression technique from the master casts. These impressions were poured to obtain test casts. Three reference distances were evaluated on each test cast by using a profile projector and compared with control groups to determine the effect of combined interaction of implant angulation and impression materials on the accuracy of implant resultant cast.Results: Statistical analysis revealed no significant difference in dimensional accuracy of the resultant casts made from two different impression materials (polyvinyl siloxane and polyether) by closed tray impression technique in parallel and angulated implants.Conclusion: On the basis of the results of this study, the use of both the impression materials i.e., polyether and polyvinyl siloxane impression is recommended for impression making in parallel as well as angulated implants.Key words: Angulated implants, implant impression, impression accuracy, impression materia
1-Benzhydryl-4-(4-chlorophenylsulfonyl)piperazine
The title compound, C23H23ClN2O2S, was synthesized by the nucleophilic substitution of 1-benzhydrylpiperazine with 4-chlorophenylsulfonyl chloride. The piperazine ring is in a chair conformation. The geometry around the S atom is that of a distorted tetrahedron. There is a large range of bond angles around the piperazine N atoms. The dihedral angle between the least-squares plane (p1) defined by the four coplanar C atoms of the piperazine ring and the benzene ring is 81.6 (1)°. The dihedral angles between p1 and the phenyl rings are 76.2 (1) and 72.9 (2)°. The two phenyl rings make a dihedral angle of 65.9 (1)°. Intramolecular C—H⋯O hydrogen bonds are present
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