1,930 research outputs found
A Micromechanical Parylene Spiral-Tube Sensor and Its Applications of Unpowered Environmental Pressure/Temperature Sensing
A multi-function micromechanical pressure/temperature sensor incorporating a microfabricated parylene
spiral tube is presented. Its visible responses in expression of
in situ rotational tube deformation enable unpowered sensing
directly from optical device observation without electrical or
any powered signal transduction. Sensor characterizations
show promising pressure (14.46°/kPa sensitivity, 0.11 kPa
resolution) and temperature (6.28°/°C sensitivity, 0.24 °C
resolution) responses. Depending on different application
requests, this sensor can be individually utilized to measure
pressure/temperature of systems having one property varying
while the other stabilized, such as intraocular or other in vivo
pressure sensing of certain apparatus inside human bodies or
other biological targets. A straightforward sensor-pair
configuration has also been implemented to retrieve the
decoupled pressure and temperature readouts, hence
ultimately realizes a convenient environmental pressure and
temperature sensing in various systems
Floating-disk parylene micro check valve
A novel micro check valve which has nearly ideal fluidic
shunting behaviors is presented. Featuring a parylene-based
floating disk, this surface-micromachined check valve
ultimately realizes both zero forward cracking pressure and
zero reverse leakage in fluidic operations. Two different
floating disk designs have been implemented to demonstrate
functionality of the microvalve. Experimental data of
underwater testing successfully show that in-channel
floating-disk valves in both designs have great fluidic
performance close to an ideal check valve, except the
additional fluidic resistance in the order of 10^(13) N-s/m^5
based on dimensions of the fabricated devices. Their
pressure loading limit have been confirmed to be higher
than 300 kPa without water leakage. This type of micro
check valve is believed to have great use of flow control in
integrated microfluidics and lab-on-a-chip applications
Job satisfaction of industrial arts teachers in secondary schools in Taiwan, Republic of China
Purposes. The purposes of this study are (1) to identify the factors which contribute to job satisfaction of industrial arts education graduates from National Kaohsuing Normal University in Taiwan, (2) to investigate and analyze factors which contribute to job satisfaction of industrial arts education graduates, and (3) to develop a flow diagram for predicting overall job satisfaction of teachers among industrial arts education graduates;Methods. The questionnaire method of data collection was used. Two hundred subjects were randomly selected from industrial arts teachers who graduated from National Kaohsuing Normal University. A questionnaire, consisting of two parts, was developed by the researcher. Part I consisted of items regarding demographic data. Part II included thirty-eight questions which referred to eight factors of job satisfaction. The statistical methods chosen for analyzing the data were regression analysis, t-test, and analysis of variance;Conclusions. Conclusions drawn from the findings were: (1) Among demographic variables, position and income level variables significantly contribute to teacher job satisfaction. (2) Position variable made significant contribution to supervision, colleagues, working conditions, and teacher preparation factors. (3) Income variable significantly contributed to working conditions, pay, and advancement factors. (4) Among eight factors relating to job satisfaction, the colleagues factor was satisfied by most industrial arts teachers. On the other hand, the working condition factor was dissatisfied by most industrial arts teachers
Anatomy of Geodesic Witten Diagrams
We revisit the so-called "Geodesic Witten Diagrams" (GWDs) \cite{ScalarGWD},
proposed to be the holographic dual configuration of scalar conformal partial
waves, from the perspectives of CFT operator product expansions. To this end,
we explicitly consider three point GWDs which are natural building blocks of
all possible four point GWDs, discuss their gluing procedure through
integration over spectral parameter, and this leads us to a direct
identification with the integral representation of CFT conformal partial waves.
As a main application of this general construction, we consider the holographic
dual of the conformal partial waves for external primary operators with spins.
Moreover, we consider the closely related "split representation" for the bulk
to bulk spinning propagator, to demonstrate how ordinary scalar Witten diagram
with arbitrary spin exchange, can be systematically decomposed into scalar
GWDs. We also discuss how to generalize to spinning cases.Comment: 40 pages, 4 figures, v2: typos corrected, references added, Appendix
E and a Mellin space discussion added, v3: typos correcte
Towards Spinning Mellin Amplitudes
We construct the Mellin representation of four point conformal correlation
function with external primary operators with arbitrary integer spacetime
spins, and obtain a natural proposal for spinning Mellin amplitudes. By
restricting to the exchange of symmetric traceless primaries, we generalize the
Mellin transform for scalar case to introduce discrete Mellin variables for
incorporating spin degrees of freedom. Based on the structures about spinning
three and four point Witten diagrams, we also obtain a generalization of the
Mack polynomial which can be regarded as a natural kinematical polynomial basis
for computing spinning Mellin amplitudes using different choices of interaction
vertices.Comment: 32 pages, 2 figures, v2: typos corrected, clarification added,
references updated, to appear in NP
Design, fabrication and characterization of monolithic embedded parylene microchannels in silicon substrate
This paper presents a novel channel fabrication technology of bulk-micromachined monolithic embedded polymer channels in silicon substrate. The fabrication process favorably obviates the need for sacrifical materials in surface-micromachined channels and wafer-bonding in conventional bulk-micromachined channels. Single-layer-deposited parylene C (poly-para-xylylene C) is selected as a structural material in the microfabricated channels/columns to conduct life science research. High pressure capacity can be obtained in these channels by the assistance of silicon substrate support to meet the needs of high-pressure loading conditions in microfluidic applications. The fabrication technology is completely compatible with further lithographic CMOS/MEMS processes, which enables the fabricated embedded structures to be totally integrated with on-chip micro/nano-sensors/actuators/structures for miniaturized lab-on-a-chip systems. An exemplary process was described to show the feasibility of combining bulk micromachining and surface micromachining techniques in process integration. Embedded channels in versatile cross-section profile designs have been fabricated and characterized to demonstrate their capabilities for various applications. A quasi-hemi-circular-shaped embedded parylene channel has been fabricated and verified to withstand inner pressure loadings higher than 1000 psi without failure for micro-high performance liquid chromatography (µHPLC) analysis. Fabrication of a high-aspect-ratio (internal channel height/internal channel width, greater than 20) quasi-rectangular-shaped embedded parylene channel has also been presented and characterized. Its implementation in a single-mask spiral parylene column longer than 1.1 m in a 3.3 mm × 3.3 mm square size on a chip has been demonstrated for prospective micro-gas chromatography (µGC) and high-density, high-efficiency separations. This proposed monolithic embedded channel technology can be extensively implemented to fabricate microchannels/columns in high-pressure microfludics and high-performance/high-throughput chip-based micro total analysis systems (µTAS)
The Stochastic Solution to a Cauchy Problem for Degenerate Parabolic Equations
We study the stochastic solution to a Cauchy problem for a degenerate
parabolic equation arising from option pricing. When the diffusion coefficient
of the underlying price process is locally H\"older continuous with exponent
, the stochastic solution, which represents the price of a
European option, is shown to be a classical solution to the Cauchy problem.
This improves the standard requirement . Uniqueness results,
including a Feynman-Kac formula and a comparison theorem, are established
without assuming the usual linear growth condition on the diffusion
coefficient. When the stochastic solution is not smooth, it is characterized as
the limit of an approximating smooth stochastic solutions. In deriving the main
results, we discover a new, probabilistic proof of Kotani's criterion for
martingality of a one-dimensional diffusion in natural scale.Comment: Keywords: local martingales, local stochastic solutions, degenerate
Cauchy problems, Feynman-Kac formula, necessary and sufficient condition for
uniqueness, comparison principl
Parylene stiction
This paper presents a preliminary study into stiction between parylene C and substrate surfaces for biocompatible check-valve applications. During fabrication, parylene C is used as the structural material for the check-valve. The substrate surfaces studied include Au, Al, Si, parylene C, XeF_2 treated Si, and silicon dioxide. Stiction between different surfaces is created after sacrificial photoresist etching. Then, the stiction is measured using blister tests, and stiction mechanisms for different materials are investigated. The devices are released with different recipes to examine their effects. Finally, the results of the study reveal methods to control the cracking pressure of parylene check-valves
Attacking Visual Language Grounding with Adversarial Examples: A Case Study on Neural Image Captioning
Visual language grounding is widely studied in modern neural image captioning
systems, which typically adopts an encoder-decoder framework consisting of two
principal components: a convolutional neural network (CNN) for image feature
extraction and a recurrent neural network (RNN) for language caption
generation. To study the robustness of language grounding to adversarial
perturbations in machine vision and perception, we propose Show-and-Fool, a
novel algorithm for crafting adversarial examples in neural image captioning.
The proposed algorithm provides two evaluation approaches, which check whether
neural image captioning systems can be mislead to output some randomly chosen
captions or keywords. Our extensive experiments show that our algorithm can
successfully craft visually-similar adversarial examples with randomly targeted
captions or keywords, and the adversarial examples can be made highly
transferable to other image captioning systems. Consequently, our approach
leads to new robustness implications of neural image captioning and novel
insights in visual language grounding.Comment: Accepted by 56th Annual Meeting of the Association for Computational
Linguistics (ACL 2018). Hongge Chen and Huan Zhang contribute equally to this
wor
Monolithic High-Aspect-Ratio Embedded Parylene Channel Technology: Fabrication, Integration, and Applications
This paper presents a novel channel fabrication
technology of monolithic bulk-micromachined embedded
channels. Based upon implementing two-step complementary dry
etching technique and conformal parylene C layer deposition,
high-aspect-ratio (internal channel height/internal channel width,
greater than 20) polymer channels with uniform quasirectangular
sidewalls have been successfully fabricated in one silicon wafer. The fabrication is completely compatible with further lithographic CMOS/MEMS process, which enables its total integration with on-chip micro sensors/actuators/structures for lab-on-a-chip applications. An exemplary process has been successfully demonstrated to verify the possibility of combining bulk micromachining and surface micromachining. This proposed formation of channels can be extensively used as beam elements in micromechanical devices or microcolumns for high-performance/high-throughput chip-based separation analysis. A
spiral parylene column longer than 1.1 m embedded in a 3.3 mm
x 3.3 mm chip has been presented as a prospective element in
micro gas-chromatography (µGC)
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