18,366 research outputs found
Hybrid Transceiver Optimization for Multi-Hop Communications
Multi-hop communication with the aid of large-scale antenna arrays will play
a vital role in future emergence communication systems. In this paper, we
investigate amplify-and-forward based and multiple-input multiple-output
assisted multi-hop communication, in which all nodes employ hybrid
transceivers. Moreover, channel errors are taken into account in our hybrid
transceiver design. Based on the matrix-monotonic optimization framework, the
optimal structures of the robust hybrid transceivers are derived. By utilizing
these optimal structures, the optimizations of analog transceivers and digital
transceivers can be separated without loss of optimality. This fact greatly
simplifies the joint optimization of analog and digital transceivers. Since the
optimization of analog transceivers under unit-modulus constraints is
non-convex, a projection type algorithm is proposed for analog transceiver
optimization to overcome this difficulty. Based on the derived analog
transceivers, the optimal digital transceivers can then be derived using
matrix-monotonic optimization. Numeral results obtained demonstrate the
performance advantages of the proposed hybrid transceiver designs over other
existing solutions.Comment: 32 pages, 6 figures. This manuscript has been submitted to IEEE
Journal on Selected Areas in Communications (special issue on Multiple
Antenna Technologies for Beyond 5G
Characterizing Manure and Litter Properties and Their Carbon Dioxide Production in an Aviary Laying-Hen Housing System
Contribution of carbon dioxide (CO2) production from manure or litter can be significant relative to animal metabolic CO2 production in housing systems with less frequent excretion removal. Such CO2 contribution should be accounted for in order to improve the accuracy of estimating building ventilation rate (VR) and animal bioenergetics based on CO2 mass balance. The objective of this study was to investigate the thermal conditions (temperature and relative humidity, or RH), production, moisture content (MC), and CO2 production of laying-hen manure on collection belts and on litter in an aviary house. Hens spent about 15.25 h day-1 in the aviary colony where their manure was deposited on the belts, and the remaining 8.75 h day-1 on the litter floor where manure was deposited on belt or litter. Manure belts were operated 1/3 of their length each day.
Results show that temperature and RH were, respectively, 1.8 ± 9.3˚C (mean ± standard deviation) and 79 ± 14% for ambient air, 18.5 ± 1.7˚C and 76 ± 16% for air near manure on belt, and 19.8 ± 1.5˚C and 80 ± 17% for air near the litter. The overall daily manure production was 35.8 ± 1.4 g hen-1 day-1 on dry basis, with 90.9% deposited on manure belt and 9.1% on litter floor. MC of manure on belt was 66.4 ± 5.8%, which was significantly higher than 14.6 ± 2.4% for the litter. The combined moisture production from manure on belt and litter was estimated to be 22.6 g day-1 hen-1. The CO2 production from as-is manure was 0.10 ± 0.06 ml s-1 kg-1 (or 0.32 ± 0. 20 ml s-1 kg-1 on dry basis), whereas CO2 production from as-is litter was much lower, 0.02 ± 0.02 ml s-1 kg-1 (or 0.03 ± 0.02 ml s-1 kg-1 on dry basis). Without litter removal, CO2 production from manure and litter could amount to as high as 8.1% of the hen’s respiration CO2 at 60 week of age. This potentially significant contribution should be considered when estimating VR or animal bioenergetics using CO2 mass balance method in aviary housing systems
Efficient Fully Convolution Neural Network for Generating Pixel Wise Robotic Grasps With High Resolution Images
This paper presents an efficient neural network model to generate robotic
grasps with high resolution images. The proposed model uses fully convolution
neural network to generate robotic grasps for each pixel using 400 400
high resolution RGB-D images. It first down-sample the images to get features
and then up-sample those features to the original size of the input as well as
combines local and global features from different feature maps. Compared to
other regression or classification methods for detecting robotic grasps, our
method looks more like the segmentation methods which solves the problem
through pixel-wise ways. We use Cornell Grasp Dataset to train and evaluate the
model and get high accuracy about 94.42% for image-wise and 91.02% for
object-wise and fast prediction time about 8ms. We also demonstrate that
without training on the multiple objects dataset, our model can directly output
robotic grasps candidates for different objects because of the pixel wise
implementation.Comment: Submitted to ROBIO 201
Ternary Bismuthide SrPtBi2: Computation and Experiment in Synergism to Explore Solid-State Materials
A combination of theoretical calculation and the experimental synthesis to
explore the new ternary compound is demonstrated in the Sr-Pt-Bi system. Since
Pt-Bi is considered as a new critical charge-transfer pair for
superconductivity, it inspired us to investigate the Sr-Pt-Bi system. With a
thorough calculation of all the known stable/metastable compounds in the
Sr-Pt-Bi system and crystal structure predictions, the thermodynamic stability
of hypothetical stoichiometry, SrPtBi2, is determined. Followed by the
high-temperature synthesis and crystallographic analysis, the first ternary
bismuthide in Sr-Pt-Bi, SrPtBi2 was prepared and the stoichiometry was
confirmed experimentally. SrPtBi2 crystallizes in the space group Pnma (S.G.
62, Pearson Symbol oP48), which matches well with theoretical prediction using
an adaptive genetic algorithm (AGA). Using first-principles calculations, we
demonstrate that the orthorhombic structure has lower formation energies than
other 112 structure types, such as tetragonal BaMnBi2 (CuSmP2) and LaAuBi2
(CuHfSi2) structure types. The bonding analysis indicates the Pt-Bi
interactions play a critical role in structural stability. The physical
properties measurements show the metallic properties with low electron-phonon
interactions at the low temperature, which agrees with the electronic structure
assessment.Comment: 12 pages, 7 figure
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