A Multi-Material Virtual Prototyping System

This paper proposes a virtual prototyping system for digital fabrication of multimaterial prototypes. It consists mainly of a topological hierarchy-sorting algorithm for processing slice contours, and a virtual simulation system for visualisation and optimisation of multi-material layered manufacturing (MMLM) processes. The topological hierarchysorting algorithm processes the hierarchy relationship of complex slice contours. It builds a parent-and-son list that defines the containment relationship of the slice contours, and subsequently arranges the contours in an appropriate sequence which facilitates optimisation of toolpath for MMLM by avoiding redundant movements. The virtual simulation system simulates MMLM processes and provides vivid visualisation of the resulting multi-material prototypes for quality analysis and optimisation of the processesThe authors would like to acknowledge the Research Grant Council of the Hong Kong SAR Government and the CRCG of the University of Hong Kong for their financial support for this project.Mechanical Engineerin

Virtual Prototyping for Rapid Product Development

link_to_OA_fulltex

Design and fabrication of double pancake coil using 2G wire for conduction cooled superconducting magnet

AbstractA large bore double pancake coil(DPC) was designed and tested with 2G HTS wire to develop the conduction cooled superconducting magnet with central field intensity of 3 T at 20K operating temperature and clear bore of 100mm at room temperature. The effect of insulation between turns of double pancake coils was tested. Two double pancake coils with and without turn to turn insulation were wound using 4mm wide 2G conductor. A temporary result suggests that the coil wound without electrical insulation can be protected from higher over current and shows improved stability

Intravital microscopic interrogation of peripheral taste sensation

Intravital microscopy is a powerful tool in neuroscience but has not been adapted to the taste sensory organ due to anatomical constraint. Here we developed an imaging window to facilitate microscopic access to the murine tongue in vivo. Real-time two-photon microscopy allowed the visualization of three-dimensional microanatomy of the intact tongue mucosa and functional activity of taste cells in response to topically administered tastants in live mice. Video microscopy also showed the calcium activity of taste cells elicited by small-sized tastants in the blood circulation. Molecular kinetic analysis suggested that intravascular taste sensation takes place at the microvilli on the apical side of taste cells after diffusion of the molecules through the pericellular capillaries and tight junctions in the taste bud. Our results demonstrate the capabilities and utilities of the new tool for taste research in vivo

Another tetraquark structure in the π+χc1\pi^+ \chi_{c1} invariant mass distribution

In this article, we assume that there exists a scalar hidden charm tetraquark state in the $\pi^+ \chi_{c1}$ invariant mass distribution, and study its mass using the QCD sum rules. The numerical result $M_{Z}=(4.36\pm0.18) \rm{GeV}$ is consistent with the mass of the Z(4250). The Z(4250) may be a tetraquark state, other possibilities, such as a hadro-charmonium resonance and a $D_1^+\bar{D}^0+ D^+\bar{D}_1^0$ molecular state are not excluded.Comment: 14 pages, 14 figure, correct some type error

Synchronization in a System of Globally Coupled Oscillators with Time Delay

We study the synchronization phenomena in a system of globally coupled oscillators with time delay in the coupling. The self-consistency equations for the order parameter are derived, which depend explicitly on the amount of delay. Analysis of these equations reveals that the system in general exhibits discontinuous transitions in addition to the usual continuous transition, between the incoherent state and a multitude of coherent states with different synchronization frequencies. In particular, the phase diagram is obtained on the plane of the coupling strength and the delay time, and ubiquity of multistability as well as suppression of the synchronization frequency is manifested. Numerical simulations are also performed to give consistent results

Dynamic characteristics of flow meters for fuel consumption measurement in ships

The dynamic characteristics of various flow meters for fuel consumption measurement aboard shipswere evaluated. The flow rate was measured using the Korea Research Institute of Standards and Science (KRISS) oil flow standard system using K-oil(density : 0.804 g/cm3, viscosity : 3.679 cSt), which has similar fluid properties as diesel oil. The flow meters were tested in a test bed that simulated the vibration conditions in ships. The vibration conditions were established in accordance to vibration standard IEC 60068-2-6 as follows: a±0.7g acceleration and 30 Hz frequency. The K-factors (mL/pulse) of various flow meters (PD meter, turbine flow meter, Coriolis flow meter, and ultrasonic flow meter) were obtained for various flow rates (60 L/h ~ 300 L/h). The PD meter, Coriolis flow meter, and ultrasonic flow meter were found to have almost constant Kfactors according to the flow rates. However, the K-factor of the turbine flow meter was reduced at a low flow rate owing to bearing friction in the turbine blade. The flow rate errors of the PD meter, Coriolis flow meter, and ultrasonic flow meter were found to be under ±0.5 % with and without vibration. However, the flow rate error of the turbine flow meter was approximately -4.3 % at a low flow rate (60 L/h) owing to the friction effect. The Coriolis flow meter had the lowest flow rate error (< 0.1%) according to the flow rate. The vibration influenced the flow rate error of the Coriolis flow meter at high flow rates owing to its measuring principle. However, the difference in flow rate errors was a negligible value (0.05 %) with and without vibration. Therefore, we confirmed that the PD meter, turbine meter, Coriolis flow meter and ultrasonic flow meter could be used for measuring flow rates in ships with a ±0.5 % flow rate error.Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .International centre for heat and mass transfer.American society of thermal and fluids engineers

Time and Amplitude of Afterpulse Measured with a Large Size Photomultiplier Tube

We have studied the afterpulse of a hemispherical photomultiplier tube for an upcoming reactor neutrino experiment. The timing, the amplitude, and the rate of the afterpulse for a 10 inch photomultiplier tube were measured with a 400 MHz FADC up to 16 \ms time window after the initial signal generated by an LED light pulse. The time and amplitude correlation of the afterpulse shows several distinctive groups. We describe the dependencies of the afterpulse on the applied high voltage and the amplitude of the main light pulse. The present data could shed light upon the general mechanism of the afterpulse.Comment: 11 figure

Neutron beam test of CsI crystal for dark matter search

We have studied the response of Tl-doped and Na-doped CsI crystals to nuclear recoils and $\gamma$'s below 10 keV. The response of CsI crystals to nuclear recoil was studied with mono-energetic neutrons produced by the $^3$H(p,n)$^3$He reaction. This was compared to the response to Compton electrons scattered by 662 keV $\gamma$-ray. Pulse shape discrimination between the response to these $\gamma$'s and nuclear recoils was studied, and quality factors were estimated. The quenching factors for nuclear recoils were derived for both CsI(Na) and CsI(Tl) crystals.Comment: 21pages, 14figures, submitted to NIM