196 research outputs found
Beamforming Codebook Compensation for Beam Squint with Channel Capacity Constraint
Analog beamforming with phased arrays is a promising technique for 5G
wireless communication in millimeter wave bands. A beam focuses on a small
range of angles of arrival or departure and corresponds to a set of fixed phase
shifts across frequency due to practical hardware constraints. In switched
beamforming, a discrete codebook consisting of multiple beams is used to cover
a larger angle range. However, for sufficiently large bandwidth, the gain
provided by the phased array is frequency dependent even if the radiation
pattern of the antenna elements is frequency independent, an effect called beam
squint. This paper shows that the beam squint reduces channel capacity of a
uniform linear array (ULA). The beamforming codebook is designed to compensate
for the beam squint by imposing a channel capacity constraint. For example, our
codebook design algorithm can improve the channel capacity by 17.8% for a ULA
with 64 antennas operating at bandwidth of 2.5 GHz and carrier frequency of 73
GHz. Analysis and numerical examples suggest that a denser codebook is required
to compensate for the beam squint compared to the case without beam squint.
Furthermore, the effect of beam squint is shown to increase as bandwidth
increases, and the beam squint limits the bandwidth given the number of
antennas in the array.Comment: 5 pages, to be published in Proc. IEEE ISIT 2017, Aachen, German
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Using Open Source Data to Identify Transit Deserts in Four Major Chinese Cities
You are viewing an article from the International Journal of Geo-Information that was in the Good Systems Network Digest in February 2020.Office of the VP for Researc
Beampattern-Based Tracking for Millimeter Wave Communication Systems
We present a tracking algorithm to maintain the communication link between a
base station (BS) and a mobile station (MS) in a millimeter wave (mmWave)
communication system, where antenna arrays are used for beamforming in both the
BS and MS. Downlink transmission is considered, and the tracking is performed
at the MS as it moves relative to the BS. Specifically, we consider the case
that the MS rotates quickly due to hand movement. The algorithm estimates the
angle of arrival (AoA) by using variations in the radiation pattern of the beam
as a function of this angle. Numerical results show that the algorithm achieves
accurate beam alignment when the MS rotates in a wide range of angular speeds.
For example, the algorithm can support angular speeds up to 800 degrees per
second when tracking updates are available every 10 ms.Comment: 6 pages, to be published in Proc. IEEE GLOBECOM 2016, Washington,
D.C., US
S3IM: Stochastic Structural SIMilarity and Its Unreasonable Effectiveness for Neural Fields
Recently, Neural Radiance Field (NeRF) has shown great success in rendering
novel-view images of a given scene by learning an implicit representation with
only posed RGB images. NeRF and relevant neural field methods (e.g., neural
surface representation) typically optimize a point-wise loss and make
point-wise predictions, where one data point corresponds to one pixel.
Unfortunately, this line of research failed to use the collective supervision
of distant pixels, although it is known that pixels in an image or scene can
provide rich structural information. To the best of our knowledge, we are the
first to design a nonlocal multiplex training paradigm for NeRF and relevant
neural field methods via a novel Stochastic Structural SIMilarity (S3IM) loss
that processes multiple data points as a whole set instead of process multiple
inputs independently. Our extensive experiments demonstrate the unreasonable
effectiveness of S3IM in improving NeRF and neural surface representation for
nearly free. The improvements of quality metrics can be particularly
significant for those relatively difficult tasks: e.g., the test MSE loss
unexpectedly drops by more than 90% for TensoRF and DVGO over eight novel view
synthesis tasks; a 198% F-score gain and a 64% Chamfer distance
reduction for NeuS over eight surface reconstruction tasks. Moreover, S3IM is
consistently robust even with sparse inputs, corrupted images, and dynamic
scenes.Comment: ICCV 2023 main conference. Code: https://github.com/Madaoer/S3IM. 14
pages, 5 figures, 17 table
Pattern of Protein Expression in Developing Wheat Grains Identified through Proteomic Analysis
Grain development is one of the biological processes, which contributes to the final grain yield. To understand the molecular changes taking place during the early grain development, we profiled proteomes of two common wheat cultivars P271 and Chinese Spring (CS) with large and small grains, respectively at three grain developmental stages (4, 8, and 12 days post anthesis). An iTRAQ (isobaric tags for relative and absolute quantitation) based proteomics approach was used for this purpose. More than 3,600 proteins were reported to accumulate during early grain development in both wheat cultivars. Of these 3,600 proteins, 130 expressed differentially between two wheat cultivars, and 306 exhibited developmental stage-specific accumulation in either or both genotypes. Detailed bioinformatic analyses of differentially expressed proteins (DEPs) from the large- and small-grain wheat cultivars underscored the developmental differences observed between them and shed light on the molecular and cellular processes contributing to these differences. In silico localization of either or both sets of DEPs to wheat chromosomes exhibited a biased genomic distribution with chromosome 4D contributing largely to it. These results corresponded well with the earlier studies, performed in common wheat, where chromosome 4D was reported to harbor QTLs for yield contributing traits specifically grain length. Collectively, our results provide insight into the molecular processes taking place during early grain development, a knowledge, which may prove useful in improving wheat grain yield in the future
Assessing the capacity of biochar to stabilize copper and lead in contaminated sediments using chemical and extraction methods
Because of its high adsorption capacity, biochar has been used to stabilize heavy metals when remediating contaminated soils; to date, however, it has seldom been used to remediate contaminated sediment. In this study, a biochar was used as a stabilization agent to remediate Cu-and Pb-contaminated sediments, collected from three locations in or close to Beijing. The sediments were mixed with a palm sawdust gasified biochar at a range of weight ratios (2.5%, 5%, and 10%) and incubated for 10, 30, or 60 days. The performance of the different treatments and the heavy metal fractions in the sediments were assessed using four extraction methods, including diffusive gradients in thin films, the porewater concentration, a sequential extraction, and the toxicity characteristic leaching procedure. The results showed that biochar could enhance the stability of heavy metals in contaminated sediments. The degree of stability increased as both the dose of biochar and the incubation time increased. The sediment pH and the morphology of the metal crystals adsorbed onto the biochar changed as the contact time increased. Our results showed that adsorption, metal crystallization, and the pH were the main controls on the stabilization of metals in contaminated sediment by biochar
Secondary infection with Streptococcus suis serotype 7 increases the virulence of highly pathogenic porcine reproductive and respiratory syndrome virus in pigs
<p>Abstract</p> <p>Background</p> <p>Porcine reproductive and respiratory syndrome virus (PRRSV) and <it>Streptococcus suis </it>are common pathogens in pigs. In samples collected during the porcine high fever syndrome (PHFS) outbreak in many parts of China, PRRSV and <it>S. suis </it>serotype 7 (SS7) have always been isolated together. To determine whether PRRSV-SS7 coinfection was the cause of the PHFS outbreak, we evaluated the pathogenicity of PRRSV and/or SS7 in a pig model of single and mixed infection.</p> <p>Results</p> <p>Respiratory disease, diarrhea, and anorexia were observed in all infected pigs. Signs of central nervous system (CNS) disease were observed in the highly pathogenic PRRSV (HP-PRRSV)-infected pigs (4/12) and the coinfected pigs (8/10); however, the symptoms of the coinfected pigs were clearly more severe than those of the HP-PRRSV-infected pigs. The mortality rate was significantly higher in the coinfected pigs (8/10) than in the HP-PRRSV- (2/12) and SS7-infected pigs (0/10). The deceased pigs of the coinfected group had symptoms typical of PHFS, such as high fever, anorexia, and red coloration of the ears and the body. The isolation rates of HP-PRRSV and SS7 were higher and the lesion severity was greater in the coinfected pigs than in monoinfected pigs.</p> <p>Conclusion</p> <p>HP-PRRSV infection increased susceptibility to SS7 infection, and coinfection of HP-PRRSV with SS7 significantly increased the pathogenicity of SS7 to pigs.</p
Multi-functional composite coating based on the dual effects of cooling and exhaust gas degradation
High-temperature hazards of asphalt pavement and pollution from car exhaust are two major problems that need to be solved in road construction. In this paper, a multifunctional composite coating has been prepared from the perspective of reducing road temperature and car exhaust degradation. The principle of heat-reflecting coating is used to reduce the road surface temperature. At the same time, the TiO2 aqueous solution with photocatalytic degradation effect is added to the heat-reflective coating material to achieve the purpose of degrading automobile exhaust degradation, creating a new type of multifunctional coating that has both cooling and exhaust degradation effects. In addition, by changing the amount of carbon black, a multi-functional coating with the best coloring is selected, so that it has better functionality and has the most suitable shade for the road surface. Finally, the cooling effect and the exhaust gas reduction effect are examined through indoor and outdoor tests and the slip resistance of the coating is tested using the pendulum method. The results show that the functional coating group has a certain ability of cooling and exhaust gas degradation compared to the normal control group without coating. For the functional coating group with different carbon black content, the functional coating (G2) with 0.9% carbon black content has the strongest overall functionality. The cooling and exhaust gas reduction effects proved to be the best. The surface cooling rate is 5.4°C, while the internal cooling rate is 4.3°C. The cumulative degradation efficiency of CO and NO is found to be 27.77%, and 73.75%, respectively
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