4,622 research outputs found
Thermal analysis comparison between two random glass fibre reinforced thermoplastic matrix composites bonded by adhesives using microwaves: preliminary results
[Abstract]: This paper compares the thermal analysis of two types of random glass fibre reinforced thermoplastic matrix composites joined by adhesives using microwave energy. Fixed frequency, 2.45 GHz, microwave facility is used to join thirty three percent by weight random glass fibre reinforced polystyrene composite [PS/GF (33%)] and thirty three percent by weight random glass fibre reinforced low density polyethylene composite [LDPE/GF (33%)]. The facility used is shown in Figure 1. With a given power level, the composites were exposed to various exposure times to microwave irradiation. The primer or coupling agent used was 5-minute two-part adhesive. The heat distribution of the samples of the two types of composites was analysed and compared. The relationship between the heat distribution and the lap shear strength of the samples was also compared and discussed
An imaging gas scintillation proportional counter for the detection of subkiloelectron-volt X-rays
A large area imaging gas scintillation proportional counter (IGSPC) was constructed for use in X-ray astronomy. The IGSPC consists of a gas scintillation proportional counted (GSPC) with a micron polyprotylene window coupled to a multiwire proportional counter (MWPC) via a calcium fluoride window. Over a sensitive area of 21 cu cm the instrument has a measured energy resolution of 17.5% (FWHM) and 1.9 mm (FWHM) spatial resolution at 1.5 keV
Pulsed THz radiation due to phonon-polariton effect in [110] ZnTe crystal
Pulsed terahertz (THz) radiation, generated through optical rectification
(OR) by exciting [110] ZnTe crystal with ultrafast optical pulses, typically
consists of only a few cycles of electromagnetic field oscillations with a
duration about a couple of picoseconds. However, it is possible, under
appropriate conditions, to generate a long damped oscillation tail (LDOT)
following the main cycles. The LDOT can last tens of picoseconds and its
Fourier transform shows a higher and narrower frequency peak than that of the
main pulse. We have demonstrated that the generation of the LDOT depends on
both the duration of the optical pulse and its central wavelength. Furthermore,
we have also performed theoretical calculations based upon the OR effect
coupled with the phonon-polariton mode of ZnTe and obtained theoretical THz
waveforms in good agreement with our experimental observation.Comment: 9 pages, 5 figure
Flavor-twisted boundary condition for simulations of quantum many-body systems
We present an approximative simulation method for quantum many-body systems
based on coarse graining the space of the momentum transferred between
interacting particles, which leads to effective Hamiltonians of reduced size
with the flavor-twisted boundary condition. A rapid, accurate, and fast
convergent computation of the ground-state energy is demonstrated on the
spin-1/2 quantum antiferromagnet of any dimension by employing only two sites.
The method is expected to be useful for future simulations and quick estimates
on other strongly correlated systems.Comment: 6 pages, 2 figure
Capturing human category representations by sampling in deep feature spaces
Understanding how people represent categories is a core problem in cognitive
science. Decades of research have yielded a variety of formal theories of
categories, but validating them with naturalistic stimuli is difficult. The
challenge is that human category representations cannot be directly observed
and running informative experiments with naturalistic stimuli such as images
requires a workable representation of these stimuli. Deep neural networks have
recently been successful in solving a range of computer vision tasks and
provide a way to compactly represent image features. Here, we introduce a
method to estimate the structure of human categories that combines ideas from
cognitive science and machine learning, blending human-based algorithms with
state-of-the-art deep image generators. We provide qualitative and quantitative
results as a proof-of-concept for the method's feasibility. Samples drawn from
human distributions rival those from state-of-the-art generative models in
quality and outperform alternative methods for estimating the structure of
human categories.Comment: 6 pages, 5 figures, 1 table. Accepted as a paper to the 40th Annual
Meeting of the Cognitive Science Society (CogSci 2018
Semiconductor nanoring lasers
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98671/1/ApplPhysLett_98_201105.pd
Lasing in a metal-clad microring resonator
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98661/1/ApplPhysLett_98_131107.pd
Soot formation and radiation in turbulent jet diffusion flames under normal and reduced gravity conditions
Most practical combustion processes, as well as fires and explosions, exhibit some characteristics of turbulent diffusion flames. For hydrocarbon fuels, the presence of soot particles significantly increases the level of radiative heat transfer from flames. In some cases, flame radiation can reach up to 75 percent of the heat release by combustion. Laminar diffusion flame results show that radiation becomes stronger under reduced gravity conditions. Therefore, detailed soot formation and radiation must be included in the flame structure analysis. A study of sooting turbulent diffusion flames under reduced-gravity conditions will not only provide necessary information for such practical issues as spacecraft fire safety, but also develop better understanding of fundamentals for diffusion combustion. In this paper, a summary of the work to date and of future plans is reported
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