Accelerating average consensus by using the information of second-order neighbours with communication delays

This article investigates the problem of accelerating average consensus in undirected and connected networks. The protocol using the information of second-order neighbours with communication delays is proposed and the delay effects on stability and the convergence speed are analysed, respectively, under an assumption about the network topologies. It is proved that, for appropriate communication delays, networks reach average consensus faster under the proposed protocol than the standard protocol using only the information of first-order neighbours. Finally, a simulation example is presented to illustrate the proposed results.     

Mixed output feedback of the finite frequency H∞ control for singularly perturbed system

This paper considers the H_∞ control problem for a class of linear singularly perturbed systems in the finite frequency range. A mixed output feedback controller comprising of a static output feedback controller and a dynamic output feedback controller is developed for the system stabilisation. Based on the generalised Kalman–Yakubovich–Popov (GKYP) lemma, the frequency-domain inequalities can be converted into linear matrix inequalities which are numerically tractable. Compared with the existing full frequency approaches, better results are obtained. Moreover, the selection methods of the cut-off frequencies in both low and high frequency ranges are extensively studied with a view to reduce the conservativeness in output feedback control design. Simulation results suggest the asymptotic validity of the main results in this paper.     

Networked predictive control of constrained linear systems with input quantisation

This article investigates the problem of stabilising predictive control for constrained systems, wherein communication from the controller to the plant input is through a digital channel subject to quantisation and delay. A novel model with structured norm-bounded uncertainties is proposed to describe control system with input quantisation. Under a multirate scheme, a delay compensation strategy is presented. The networked predictive control synthesis approach is developed by solving a finite receding horizon optimisation problem with free control moves. It is shown that the proposed predictive controller not only efficiently reduces the negative effects of the quantisation and communication delays but also guarantees the closed-loop stability and satisfies constraints. Finally, a simulation example illustrates the effectiveness of the derived method.     

Filtering method for SAR interferograms with strong noise

We develop a filtering method for SAR interferograms with strong noise based on the concept of the Vondrák filter and the commonly used Goldstein filter. The one‐dimensional Vondrák filter is first extended to two dimensions, and then utilized to smooth the Fourier spectra of overlapped interferogram patches. The smoothed spectra are then back‐transformed into the interferogram space. Experimental results with simulated and real datasets show that the proposed filter can eliminate up to 70% of noise in a SAR interferogram. The results also show a 15% to 35% improvement over some of the existing filters when the noise in an interferogram is strong, and the stronger the noise in an interferogram, the greater is the improvement.     

Multisatellite observations and numerical simulation of an along‐coast cumulus cloud line induced by sea‐breeze circulation

A coastal cumulus cloud‐line formation along the east coast of the USA was observed on a National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellite (POES) Advanced Very High Resolution Radiometer (AVHRR) satellite image from 17 August 2001. The cloud line starts to form at about 16:00 UTC (local 12:00 noon) and follows the coastline from Florida to North Carolina. The length and width of the cloud line are about 850 km and 8.5 km, respectively. A 15‐min interval sequence of NOAA Geostationary Operational Environmental Satellite (GOES) images shows that the cloud line maintains the shape of the coastline and penetrates inland for more than 20 km over the next 6‐h timespan. Model simulation with actual atmospheric conditions as inputs shows that the cloud line is formed near the land–sea surface temperature (SST) gradient. The synoptic flow at all model levels is in the offshore direction prior to 16:00 UTC whereas low‐level winds (below 980 hPa) reverse direction to blow inland after 16:00 UTC. This reversal is due to the fact that local diurnal heating over the land takes place on shorter time‐scales than over the ocean. The vertical wind at these levels becomes stronger as the land–SST increases during the summer afternoon, and the leading edge of the head of the inland wind ascends from 920 hPa to about 850 hPa in the 3 h after 16:00 UTC. Model simulation and satellite observations show that the cloud line becomes very weak after 21:00 UTC when the diurnal heating decreases.     

An extended multiple-component scattering model for PolSAR images

An extended multiple-component scattering model (MCSM) is proposed for polarimetric synthetic aperture radar (PolSAR) image decomposition. The MCSM is an extension of the three-component scattering model (TCSM), and it describes single-bounce, double-bounce, volume, helix and wire scattering as elementary scattering mechanisms in the analysis of PolSAR images. The proposed MCSM is demonstrated with German Aerospace Centre (DLR) experimental SAR (ESAR) L-band fully polarized images of the Oberpfaffenhofen Test Site Area (DE), Germany. Double-bounce, helix and wire scattering are found to be predominant in urban areas and the results confirm that the MCSM is effective for analysis of buildings in urban areas. A comparison of the TCSM and its extended models is also implemented.     

Remote sensing interpretation of areas with hydrocarbon microseepage in northeast China using Landsat-7/ETM+ data processing techniques

Landsat-7 Enhanced Thematic Mapper Plus (ETM+) images were used to interpret hydrocarbon-induced alterations in the northwestern part of the Songliao Basin, northeast China. Spectral enhancements for locating hydrocarbon-related minerals on images included principal component analysis (PCA), band ratioing, optimum index factor (OIF) and false colour composite (FCC). Four principal component (PC) and four band ratio images showed outstanding spectral response of hydrocarbon-induced mineral and sediment assemblages: 1345-PC3 (third PC image on bands 1, 3, 4 and 5), 1357-PC3, 2357-PC3 and 3457-PC4, and band ratios 3/1, 4/3, 7/5 and 4/3–2/3. Five OIF-defined FCCs were informative and clear for anomaly interpretation. Consequently, heavy oil prospect areas totalling 159 km² were delineated. Acidolysis hydrocarbon measurements of ground soil samples suggest high soil concentrations of light hydrocarbons, indicating that the tonal anomalies in the images have a geological origin. Thus, remote sensing interpretation can be a useful primary exploration tool in hydrocarbon-altered areas, provided that techniques are adapted to site characteristics.     

铁粉还原应用于α-卤代羰基化合物的卤素消除研究

对铁粉还原应用于α-卤代羰基化合物的卤素消除进行了研究,实验证明,铁粉不仅可用于4-溴-2-氯-2-甲基-卜茚酮的脱氯反应,也可用于2,4-二溴-5-甲氧基-6-叔丁基-2-甲基-l-茚酮的脱溴反应,并且经过了工业化验证,给出了工业化放大时的建议.     

Feasibility study for thermal protection by microencapsulated phase change micro/nanoparticles during cryosurgery

Although considerable progresses have been made in cryosurgery to treat tumor, thermal injury to collateral structures is still a known complication of cryosurgery. In this study, a new method was proposed to prevent the healthy tissue around the cancerous tissue from thermal injury by microencapsulated phase change micro/nanoparticles, in which the phase change materials (PCMs) with large latent heat and low thermal conductivity are microencapsulated by liposome and delivered to the healthy tissue by mainline, arterial injection, hypodermic injection or direct injection. The three-dimensional transient temperature field in human body containing one tumor and embedded PCMs in the surrounding healthy tissue was numerically studied. The effects of the PCMs concentration, the phase change temperature, the temperature range near the phase change point, the latent heat and the PCMs distribution (especially the number of sides that PCMs cover, and the distance between the PCMs domain and the cancerous domain) were further discussed. The computational analysis showed that embedding PCMs in the healthy tissue around the cancerous tissue can significantly reduce the cryoinjury to the surrounding healthy tissue. The result also suggested that not embedding the PCMs directly adjacent to the cancerous tissue will help to improve the protection efficacy.