A Randomized Greedy Algorithm for Near-Optimal Sensor Scheduling in Large-Scale Sensor Networks

We study the problem of scheduling sensors in a resource-constrained linear dynamical system, where the objective is to select a small subset of sensors from a large network to perform the state estimation task. We formulate this problem as the maximization of a monotone set function under a matroid constraint. We propose a randomized greedy algorithm that is significantly faster than state-of-the-art methods. By introducing the notion of curvature which quantifies how close a function is to being submodular, we analyze the performance of the proposed algorithm and find a bound on the expected mean square error (MSE) of the estimator that uses the selected sensors in terms of the optimal MSE. Moreover, we derive a probabilistic bound on the curvature for the scenario where{\color{black}{ the measurements are i.i.d. random vectors with bounded $\ell_2$ norm.}} Simulation results demonstrate efficacy of the randomized greedy algorithm in a comparison with greedy and semidefinite programming relaxation methods

Quality ratings based on the EPHPP protocol.

<p>Quality ratings based on the EPHPP protocol.</p

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Article compliance and global ROB assessment rating for inclusion in final analysis.

<p>Article compliance and global ROB assessment rating for inclusion in final analysis.</p

Studies included in synthesis.

<p>Studies included in synthesis.</p

PRISMA-P flow chart of study selection.

<p>PRISMA-P flow chart of study selection.</p

Tribology of dust-stop seals of mixing machines

Dust stop seals are widely used in powder and rubber mixing industries. Design of the sealing system requires a continuous supply of pressurised lubricant, which is not recycled because of the risk of contamination. There is also the potential of large volume leakage of oil due to poor sealing, increasing operational costs and necessitating remedial measures to avoid environmental protection. Furthermore, the seal faces are prone to failure in relatively short periods of time due to reduced gap and lubricant leakage. The paper presents an analytical method and numerical predictions based on Reynolds equation under combined hydrodynamic and hydrostatic conditions with the entrant lubricant through hydraulically loaded feedholes. The validity of these methods is ascertained through comparison with a more complex but time-consuming solution of Navier-Stokes equations. The numerical predictions allow for determining the prevailing tribological contact conditions and assessing its suitability for evaluating the sealing performance of mixing machinery.</p

Estimation of apparent tumor vascular permeability from multiphoton fluorescence microscopic images of P22 rat sarcomas in vivo

Objective: To develop an image processing-based method to quantify the rate of extravasation of fluorescent contrast agents from tumor microvessels, and to investigate the effect of the tumor vascular disrupting agent combretastatin A-4-P (CA-4-P) on apparent tumor vascular permeability to 40 kDa fluorescein isothiocyanate (FITC) labeled dextran. Methods: Extravasation of FITC-dextran was imaged in 3 dimensions over time within P22 sarcomas growing in dorsal skin flap "window chambers" in BDIX rats using multiphoton fluorescence microscopy. Image processing techniques were used to segment the data into intra- and extravascular regions or classes. Quantitative estimates of the tissue influx (vascular leakage) rate constant, Ki, were obtained from the time courses of the fluorescence intensities in the two classes. Apparent permeability, P, was calculated, assuming Ki = PS/V, where S is vascular surface area in tumor volume V. Results: Combining image processing and kinetic analysis algorithms with multiphoton fluorescence microscopy enabled quantification of the rate of tumor vascular leakage, averaged over a large number of vessels. Treatment with CA-4-P caused a significant increase in Ki from 1.13 0.33 to 2.59 +- 0.20 (s-1 x 10-4; mean +- SEM), equivalent to an increase in P from 12.76 3.36 to 30.94 +- 2.64 (cm s-1 x 10-7). Conclusions: A methodology was developed that provided evidence for a CA-4-P-induced increase in tumor macromolecular vascular permeability, likely to be central to its anti-cancer activity

Efficacy of GDC-0941 and PD 0325901 in mice bearing human colorectal tumour xenografts.

<p>± standard deviation (SD) and the median RTV3 or RTV4 for each group (± interquartile range (IR)). Time taken in days for HCT116 and HT29 tumour xenografts to reach three or four times their initial volume (time to RTV3 or RTV4) when treated with either vehicle control, 1 mg/kg PD 0325901 and 100 mg/kg GDC-0941 alone, or 1 mg/kg PD 0325901 and 100 mg/kg GDC-0941 in combination, p.o. once daily for 14 days. Data are presented as the mean time to RTV3 or RTV4 for the mice in each group </p