Delay-dependent stabilization of stochastic interval delay systems with nonlinear disturbances

This is the post print version of the article. The official published version can be obtained from the link below - Copyright 2007 Elsevier Ltd.In this paper, a delay-dependent approach is developed to deal with the robust stabilization problem for a class of stochastic time-delay interval systems with nonlinear disturbances. The system matrices are assumed to be uncertain within given intervals, the time delays appear in both the system states and the nonlinear disturbances, and the stochastic perturbation is in the form of a Brownian motion. The purpose of the addressed stochastic stabilization problem is to design a memoryless state feedback controller such that, for all admissible interval uncertainties and nonlinear disturbances, the closed-loop system is asymptotically stable in the mean square, where the stability criteria are dependent on the length of the time delay and therefore less conservative. By using Itô's differential formula and the Lyapunov stability theory, sufficient conditions are first derived for ensuring the stability of the stochastic interval delay systems. Then, the controller gain is characterized in terms of the solution to a delay-dependent linear matrix inequality (LMI), which can be easily solved by using available software packages. A numerical example is exploited to demonstrate the effectiveness of the proposed design procedure.This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant GR/S27658/01, the Nuffield Foundation of the UK under Grant NAL/00630/G, and the Alexander von Humboldt Foundation of Germany

The improved separation method of coherent sources with two measurement surfaces based on statistically optimized near-field acoustical holography

A technique for separating coherent sources measured by two parallel arrays is proposed. The two measurement surfaces located in the opposite directions of the coherent sources. Similar to separate the aim source from background noise, this method can separate the single source from coherent sources, which makes the sound field information of single source in complex environment more accurate. Such improved separation method based on statistically optimized near-field acoustical holography, according to the sound pressure relationship between measurement surfaces and reconstruction surfaces to separate the sources, reduces the measurement data and obtains higher precision of reconstruction. The present paper uses the improved separation method to obtain the single source results from numerical simulations, gives the relative reconstruction errors with frequency from 100 Hz to 1400 Hz, and practical measurement

Multistaged discharge constructing heterostructure with enhanced solid-solution behavior for long-life lithium-oxygen batteries.

Inferior charge transport in insulating and bulk discharge products is one of the main factors resulting in poor cycling stability of lithium-oxygen batteries with high overpotential and large capacity decay. Here we report a two-step oxygen reduction approach by pre-depositing a potassium carbonate layer on the cathode surface in a potassium-oxygen battery to direct the growth of defective film-like discharge products in the successive cycling of lithium-oxygen batteries. The formation of defective film with improved charge transport and large contact area with a catalyst plays a critical role in the facile decomposition of discharge products and the sustained stability of the battery. Multistaged discharge constructing lithium peroxide-based heterostructure with band discontinuities and a relatively low lithium diffusion barrier may be responsible for the growth of defective film-like discharge products. This strategy offers a promising route for future development of cathode catalysts that can be used to extend the cycling life of lithium-oxygen batteries

Dichlorido(dipyrido[3,2-a:2′,3′-c]phenazine)manganese(II)

The complete mol­ecule of the title compound, [MnCl2(C18H10N4)2], is generated by crystallographic twofold symmetry with the Mn atom lying on the rotation axis. The Mn coordination geometry is a distorted cis-MnCl2N4 octa­hedron, arising from two N,N′-bidentate dipyrido[3,2-a:2′,3′-c]phenazine (DPPZ) ligands and two chloride ions. In the crystal structure, neighbouring mononuclear units pack together through π–π contacts between the DPPZ rings [shortest centroid–centroid distance = 3.480 (2) Å], leading to a chain-like structure along [001]. C—H⋯Cl hydrogen bonds complete the structure

Superior biological performance and osteoinductive activity of Si-containing bioactive bone regeneration particles for alveolar bone reconstruction

Bone grafting materials for repair of alveolar bone deficits have improved markedly in recent years, increasing the applicability and success of oral implantology. The long-term success rate of dental implant surgery is strongly dependent on the quality and stability of residual bone tissue. Therefore, reconstruction of resorbed alveolar bone is a challenge for clinicians. In the present study, we have developed bioactive bone regeneration particles (BRPs) using amorphous calcium phosphate and 58S bioglass as raw materials. The structural characteristics, biocompatibility, and osteoinductivity of these BRPs were compared to commercially available bovine spongy bone (BSB) without organic components. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) showed that BRPs were composed of β-tricalcium phosphate (β-TCP) and calcium silicate in the form of hexagonal crystals, while BSB was mainly hydroxyapatite (HA) arranged in orderly nano-sized crystals. The viability of human bone marrow mesenchymal stem cells (hBMSCs) cultured in BRP-containing medium was roughly equal to that of hBMSCs in control medium. Moreover, hBMSCs in BRP medium exhibited greater proliferation rates, substrate attachment, alkaline phosphatase (ALP) activity, alizarin red staining intensity, and expression levels of osteogenic-related genes (COL-I, OCN, Runx-2, ALP, BSP) than hBMSCs in BSB medium, indicating the superior osteoinductivity of BRPs. Silicon ions released from BRPs during cell culture were crucial for these enhanced biological properties. BRPs also demonstrated superior osteoconduction and osteoinduction properties for bone defect repair, suggesting promise for alveolar bone repair surgery

The First Data Release of the Beijing-Arizona Sky Survey

The Beijing-Arizona Sky Survey (BASS) is a new wide-field legacy imaging survey in the northern Galactic cap using the 2.3m Bok telescope. The survey will cover about 5400 deg$^2$ in the $g$ and $r$ bands, and the expected 5$\sigma$ depths (corrected for the Galactic extinction) in the two bands are 24.0 and 23.4 mag, respectively. BASS started observations in January 2015, and has completed about 41% of the whole area as of July 2016. The first data release contains both calibrated images and photometric catalogs obtained in 2015 and 2016. The depths of single-epoch images in the two bands are 23.4 and 22.9 mag, and the full depths of three epochs are about 24.1 and 23.5 mag, respectively.Comment: 16 pages, published by A

Highly hydrated paramagnetic amorphous calcium carbonate nanoclusters as a superior MRI contrast agent

Amorphous calcium carbonate plays a key role as transient precursor in the early stages of biogenic calcium carbonate formation in nature. However, due to its instability in aqueous solution, there is still rare success to utilize amorphous calcium carbonate in biomedicine. Here, we report the mutual effect between paramagnetic gadolinium ions and amorphous calcium carbonate, resulting in ultrafine paramagnetic amorphous carbonate nanoclusters in the presence of both gadolinium occluded highly hydrated carbonate-like environment and poly(acrylic acid). Gadolinium is confirmed to enhance the water content in amorphous calcium carbonate, and the high water content of amorphous carbonate nanoclusters contributes to the much enhanced magnetic resonance imaging contrast efficiency compared with commercially available gadolinium-based contrast agents. Furthermore, the enhanced T1 weighted magnetic resonance imaging performance and biocompatibility of amorphous carbonate nanoclusters are further evaluated in various animals including rat, rabbit and beagle dog, in combination with promising safety in vivo. Overall, exceptionally facile mass-productive amorphous carbonate nanoclusters exhibit superb imaging performance and impressive stability, which provides a promising strategy to design magnetic resonance contrast agent

Campus sewage treatment in multilayer horizontal subsurface flow constructed wetlands: nitrogen removal and microbial community distribution

Horizontal subsurface flow constructed wetlands (HSCWs) are widely used for wastewater treatment. The objective of this study was to assess the effects of substrate size selection and layout optimisation on pollutant removal and microbial community distribution responses in HSCWs. Three pilot-scale constructed wetlands (CWs) were established at Guilin University of Technology, China, to treat campus sewage. The three CWs included monolayer (CW1), three-layer (CW2), and six-layer (CW3) substrate structures with the hydraulic conductivity of the substrate increasing from the surface to the bottom in the multilayer CWs. Under an aerial influent loading rate of 0.38 m per day (volumetric loading rate of 0.63 per day), CW3 exhibited the highest removal performance for chemical oxygen demand (COD), NH4+-N, and total nitrogen (TN), with mean values of 81, 81, and 74%, respectively, followed by CW2 (68, 71, and 60%, respectively) and CW1 (56, 46, and 41%, respectively). Nitrification was demonstrated to be the limiting factor of TN removal, and higher TN removal performance in the multilayer CWs was attributed to the higher proportions of nitrifiers, including ammonia-oxidising bacteria (AOB) and nitrite-oxidising bacteria (NOB). Moreover, 454-pyrosequencing showed a significantly different spatial distribution of the N-transforming microbial community in multilayer HSCWs with substrate layout optimisation

Compressed glassy carbon: An ultrastrong and elastic interpenetrating graphene network

Carbon’s unique ability to have both sp2 and sp3 bonding states gives rise to a range of physical attributes, including excellent mechanical and electrical properties. We show that a series of lightweight, ultrastrong, hard, elastic, and conductive carbons are recovered after compressing sp2-hybridized glassy carbon at various temperatures. Compression induces the local buckling of graphene sheets through sp3 nodes to form interpenetrating graphene networks with long-range disorder and short-range order on the nanometer scale. The compressed glassy carbons have extraordinary specific compressive strengths—more than two times that of commonly used ceramics—and simultaneously exhibit robust elastic recovery in response to local deformations. This type of carbon is an optimal ultralight, ultrastrong material for a wide range of multifunctional applications, and the synthesis methodology demonstrates potential to access entirely new metastable materials with exceptional properties