314 research outputs found
Measurement of permeability for ferrous metallic plates using a novel lift-off compensation technique on phase signature
Lift-off of sensor affects the prediction of electromagnetic properties for
both ferrous and non-ferrous steel plates. In this paper, we developed a
strategy to address this issue for ferrous plates. With increased lift-off, the
phase of the measured impedance for steel plates reduces. Meanwhile, the
magnitude of the impedance signal decreases. Based on these facts, a phase
compensation algorithm is developed which corrects the phase change due to
lift-off considering the magnitude of the impedance signal. Further, a new
magnetic permeability prediction technique is presented, which has been
validated by analytical and measured results. With this new technique, the
error in permeability prediction is less than 2% within the range of lift-offs
tested
Dual-Feed Small-Size Penta-Band PIFA for LTE/WWAN Mobile Handset Applications
A dual-feed small-size penta-band PIFA for LTE/WWAN mobile handset applications is presented. The proposed PIFA is composed of a simple U-shaped patch with dual-shorting pins connected to the ground plane. The patch, having a low profile of 5 mm, has dimensions of about 10 × 35 mm2. The antenna is excited at one arm of the U-shaped radiating patch to cover the higher band of GSM1800/1900/UMTS2100/LTE2300/2500, while it is excited at the other arm to realize the GSM900. In this way, the proposed PIFA achieves enhanced bandwidth coverage with no increased dimensions and additional active switches. In addition, the matching networks, employed on both feeds, ensure a high electrical insulation between the low and the high frequency bands, covered by the antenna. The measured antenna efficiency is 45%~50% and over 60% for the lower band and the higher band, respectively. A prototype of the proposed PIFA with dual-feed and dual-shorting pins was fabricated. The measured results including reflection coefficients and radiation characteristics are presented
Scene Graph Generation with External Knowledge and Image Reconstruction
Scene graph generation has received growing attention with the advancements
in image understanding tasks such as object detection, attributes and
relationship prediction,~\etc. However, existing datasets are biased in terms
of object and relationship labels, or often come with noisy and missing
annotations, which makes the development of a reliable scene graph prediction
model very challenging. In this paper, we propose a novel scene graph
generation algorithm with external knowledge and image reconstruction loss to
overcome these dataset issues. In particular, we extract commonsense knowledge
from the external knowledge base to refine object and phrase features for
improving generalizability in scene graph generation. To address the bias of
noisy object annotations, we introduce an auxiliary image reconstruction path
to regularize the scene graph generation network. Extensive experiments show
that our framework can generate better scene graphs, achieving the
state-of-the-art performance on two benchmark datasets: Visual Relationship
Detection and Visual Genome datasets.Comment: 10 pages, 5 figures, Accepted in CVPR 201
Uniform sets with few progressions via colorings
Ruzsa asked whether there exist Fourier-uniform subsets of with density and 4-term arithmetic progression (4-APs)
density at most , for arbitrarily large . Gowers constructed
Fourier uniform sets with density and 4-AP density at most
for some small constant . We show that an affirmative
answer to Ruzsa's question would follow from the existence of an
-coloring of without symmetrically colored 4-APs. For a broad
and natural class of constructions of Fourier-uniform subsets of , we show that Ruzsa's question is equivalent to our arithmetic
Ramsey question.
We prove analogous results for all even-length APs. For each odd ,
we show that there exist -uniform subsets of
with density and -AP density at most .
We also prove generalizations to arbitrary one-dimensional patterns.Comment: 20 page
Functional Studies Of 5-Carboxyaminoimidazole Ribonucleotide Synthetase And Mutase From Thermotoga Maritima
De novo purine biosynthesis is divergent depending upon the organism. In bacteria, yeasts and plants, 5-aminoimidazole ribonucleotide (AIR) is converted to 4-carboxyaminoimidazole ribonucleotide (CAIR) by N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) synthetase (PurK) and N5-CAIR mutase (Class I PurE). In animals, AIR is converted into CAIR by AIR carboxylase (Class II PurE). The distinction makes PurK and Class I PurE good targets in design of antimicrobial drugs. N5-CAIR is chemically unstable with t1/2 of about 0.9 minutes at pH 7.8 and 37 °C. If the production of N5-CAIR is not regulated relative to its conversion to CAIR, ATP utilization can rapidly become non-stoichiometric. One mechanism to study this problem is to investigate how the problem is dealt with under conditions in which N5-CAIR is even more unstable, such as at higher temperature. Thermotoga maritima, originally isolated from geothermal heated marine sediment, is a thermophilic bacterium whose optimal growth temperature is 80°C. The TM0446 and TM0447 genes of Thermotoga maritima encode a phosphoribosylaminoimidazole mutase (PurE) and synthetase (PurK) individually. We cloned genes and expressed both proteins. Enzyme kinetic analyses for each enzyme indicate that these enzymes follow the same pathway as those found in E. coli. Studies of the stoichiometry of the reaction reveal that at elevated temperature, the reactions are stoichiometric as long as the ratio of PurE and PurK is 1:1. When this ratio is lower, ATP consumption becomes non-stoichiometric. We have also examined whether there is a complex formed between these enzymes. Our data indicate that each enzyme is capable of regulating the activity of the other. This suggests that a complex is formed by these two enzymes
An equivalent-effect phenomenon in eddy current non-destructive testing of thin structures
The inductance/impedance due to thin metallic structures in non-destructive
testing (NDT) is difficult to evaluate. In particular, in Finite Element Method
(FEM) eddy current simulation, an extremely fine mesh is required to accurately
simulate skin effects especially at high frequencies, and this could cause an
extremely large total mesh for the whole problem, i.e. including, for example,
other surrounding structures and excitation sources like coils. Consequently,
intensive computation requirements are needed. In this paper, an
equivalent-effect phenomenon is found, which has revealed that alternative
structures can produce the same effect on the sensor response, i.e. mutual
impedance/inductance of coupled coils if a relationship (reciprocal
relationship) between the electrical conductivity and the thickness of the
structure is observed. By using this relationship, the mutual
inductance/impedance can be calculated from the equivalent structures with much
fewer mesh elements, which can significantly save the computation time. In eddy
current NDT, coils inductance/impedance is normally used as a critical
parameter for various industrial applications, such as flaw detection, coating
and microstructure sensing. Theoretical derivation, measurements and
simulations have been presented to verify the feasibility of the proposed
phenomenon
A joint multi user detection scheme for UWB sensor networks using waveform division multiple access
A joint multiuser detection (MUD) scheme for wireless sensor networks (WSNs) is proposed to suppress multiple access interference (MAI) caused by a large number of sensor nodes. In WSNs, waveform division multiple access ultra-wideband (WDMA-UWB) technology is well-suited for robust communications. Multiple sensor nodes are allowed to transmit modulated signals by sharing the same time periods and frequency bands using orthogonal pulse waveforms. This paper employs a mapping function based on the optimal multiuser detection (OMD) to map the received bits into the mapping space where error bits can be distinguished. In order to revise error bits caused by MAI, the proposed joint MUD scheme combines the mapping function with suboptimal algorithms. Numerical results demonstrate that the proposed MUD scheme provides good performances in terms of suppressing MAI and resisting near-far effect with low computational complexity
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