1,008 research outputs found
Proportional fairness in wireless powered CSMA/CA based IoT networks
This paper considers the deployment of a hybrid wireless data/power access
point in an 802.11-based wireless powered IoT network. The proportionally fair
allocation of throughputs across IoT nodes is considered under the constraints
of energy neutrality and CPU capability for each device. The joint optimization
of wireless powering and data communication resources takes the CSMA/CA random
channel access features, e.g. the backoff procedure, collisions, protocol
overhead into account. Numerical results show that the optimized solution can
effectively balance individual throughput across nodes, and meanwhile
proportionally maximize the overall sum throughput under energy constraints.Comment: Accepted by Globecom 201
Modeling the performance of distributed fiber optical sensor based on spontaneous Brillouin scattering
An optical model to simulate the distributed fiber optical sensor based on spontaneous Brillouin spectrum is derived. The reliability of this model is validated with experimental measurements. Using this analytical expression, parametric studies are conducted to investigate impacts of key factors including fiber loss, signal to noise ratio, bandwidth and
scanning step on the optical fiber sensor measurement error. The simulation results exhibit good agreement with previous published calculation results. Applying this novel model into the data interpretation, measurement error of distributed fiber optical sensor based on spontaneous Brillouin scattering can be better controlled
Constrained monotone mean-variance problem with random coefficients
This paper studies the monotone mean-variance (MMV) problem and the classical
mean-variance (MV) problem with convex cone trading constraints in a market
with random coefficients. We provide semiclosed optimal strategies and optimal
values for both problems via certain backward stochastic differential equations
(BSDEs). After noting the links between these BSDEs, we find that the two
problems share the same optimal portfolio and optimal value. This generalizes
the result of Shen and Zou SIAM J. Financial Math., 13 (2022), pp.
SC99-SC112 from deterministic coefficients to random ones
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Simulation of BOTDA and Rayleigh COTDR systems to study the impact of noise on dynamic sensing
This is the author acepted manuscript. It is currently under an indefinite embargo pending publication of the final version.Dynamic distributed sensing of strain and temperature is the key for real-time structural health monitoring (SHM) across a wide range of geo-engineering challenges, for which Brillouin Optical Time Domain Analysis (BOTDA) and Rayleigh Coherent Optical Time Domain Reflectometry (COTDR) are promising candidates. A noise model with specific parametric simulation of the two systems has been developed. Noise in both laser(s) and detector is independently simulated to identify the key noise sources. In this simulation, although averaging can significantly enhance the signal-to-noise ratio (SNR) in the two systems, it is a barrier to dynamic sensing due to its time-consuming accumulation procedure. The sequence of averaging in the signal processing workflow can vary the SNR for the two systems. The system components should be optimized to reduce the averaging times to achieve the required system specifications, especially the dynamic sensing performance.This project was carried out under the UCL-Cambridge Centre
for Doctoral Training in Photonic Systems Development, with funding
from EPSRC (EP/G037256/1) gratefully acknowledged. The funding
from Cambridge Centre for Smart Infrastructure and Construction is
acknowledged
Segmentation, Reconstruction, and Analysis of Blood Thrombus Formation in 3D 2-Photon Microscopy Images
We study the problem of segmenting, reconstructing, and analyzing the structure growth of thrombi (clots) in blood vessels in vivo based on 2-photon microscopic image data. First, we develop an algorithm for segmenting clots in 3D microscopic images based on density-based clustering and methods for dealing with imaging artifacts. Next, we apply the union-of-balls (or alpha-shape) algorithm to reconstruct the boundary of clots in 3D. Finally, we perform experimental studies and analysis on the reconstructed clots and obtain quantitative data of thrombus growth and structures. We conduct experiments on laser-induced injuries in vessels of two types of mice (the wild type and the type with low levels of coagulation factor VII) and analyze and compare the developing clot structures based on their reconstructed clots from image data. The results we obtain are of biomedical significance. Our quantitative analysis of the clot composition leads to better understanding of the thrombus development, and is valuable to the modeling and verification of computational simulation of thrombogenesis
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