Real-Time Warning System of Regional Landslides Supported by WEBGIS and its Application in Zhejiang Province, China

AbstractAs one of the provinces of highest economic growth in coastal China, Zhejiang Province is experiencing serious geological disasters during the past development of economy, which are mainly induced by intensive rainfall during typhoon season or by long-term rainfall from May to June every year. Thus, supported by WEBGIS, a real-time warning system of regional landslides is studied. According to the characteristic of rainfall in Zhejiang province, the study divides the province into typhoon region and non-typhoon region, using statistic approach to study the correlation of regional landslides hazards and rainfall, rainfall intensity of typhoon region and non-typhoon region. By correlation analysis, effective rainfall model is defined, and the thresholds of effective rainfall and rainfall intensity are obtained. Combining these thresholds with spatial prediction production of landslides hazards, predictive models for landslide warning of Zhejiang Province are established. Then a real-time warning system of regional landslides explored by WEBGIS software is successfully developed considering both regional geology and rainfall process information

Circumferential defect detection using ultrasonic guided waves: An efficient quantitative technique for pipeline inspection

Purpose: Quantitatively detecting surface defects in a circular annulus with high levels of accuracy and efficiency has been paid more attention by researchers. The purpose of this study is to investigate the theoretical dispersion equations for circumferential guided waves and then develop an efficient technique for accurate reconstruction of defects in pipes. Design/methodology/approach: The methodology applied to determine defects in pipelines includes four steps. First, the theoretical work is carried out by developing the appropriate dispersion equations for circumferential guided waves in a pipe. In this phase, formulations of strain-displacement relations are derived in a general equidistant surface coordinate. Following that, a semi-analytical finite element method (SAFEM) is applied to solve the dispersion equations. Then, the scattered fields in a circular annulus are calculated using the developed hybrid finite element method and simulation results are in accord with the law of conservation of energy. Finally, the quantitative detection of Fourier transform (QDFT) approach is further enhanced to efficiently reconstruct the defects in the circular annuli, which have been widely used for engineering applications. Findings: Results obtained from four numerical examples of flaw detection problems demonstrate the correctness of the developed QDFT approach in terms of accuracy and efficiency. Reconstruction of circumferential surface defects using the extended QDFT method can be performed without involving the analytical formulations. Therefore, the streamlined process of inspecting surface defects is well established and this leads to the reduced time in practical engineering tests. Originality/value: In this paper, the general dispersion equations for circumferential ultrasonic guided waves have been derived using an equidistant surface coordinate and solved by the SAFEM technique to discover the relationship between wavenumber of a wave and its frequency. To reconstruct defects with high levels of accuracy and efficiency, the QDFT approach has been further enhanced to inspect defects in the annular structure

Optimization of Nano-Rotor Blade Airfoil Usinf Controlled Elitist NSGA-II

The aerodynamic performance of airfoil at ultra-low Reynolds number has a great impact on the propulsive performance of nano rotor. Therefore, the optimization of airfoil is necessary before the design of nano rotor. Nano rotor blade airfoil optimization is a multi-objective problem since the airfoil suffers a wide range of Reynolds number which increases the difficulty of optimization. In this paper, the airfoil of nano rotor was optimized based on the controlled elitist Non-dominated Sorting Genetic Algorithm II (NSGA-II) coupling with the parameterization method of Class function/Shape function Transformation technique (CST) and the multi-objectives function processing method of statistical definition of stability. An airfoil was achieved with the thickness of 2% and the maximum camber of 5.6% at 2/3 of chord. Airfoil optimized exhibits a good aerodynamic performance at ultra-low Reynolds number according to the computational results. And comparisons were carried out between the performance of the rotor designed with airfoil optimized and that of the rotor designed with AG38 airfoil, which showed that the airfoil optimized was suitable for rotor design

A novel approach to surface defect detection

Defects or flaws in highly loaded structures have a significant impact on the structural integrity. Early inspection of faults can reduce the likelihood of occurrence of potential disasters and limit the damaging effects of destructions. According to our previous work, a novel approach called as Quantitative Detection of Fourier Transform (QDFT) using guided ultrasonic waves is developed in this paper for efficiently detecting defects in pipeline structures. Details of this fast method consist of three steps: First, an in-house finite element code has been developed to calculate reflection coefficients of guided waves travelling in the pipe. Then, based on boundary integral equations and Fourier transform of space-wavenumber domain, theoretical formulations of the quantitative detection are derived as a function of wavenumber using Born approximation. This lays a solid foundation for QDFT method, in which a reference model in a problem with a known defect is utilized to effectively evaluate the unknown defects. Finally, the location and shape of the unknown defect are reconstructed using signal processing for noise removal. Several examples are presented to demonstrate the correctness and efficiency of the proposed methodology. It is concluded that the general two-dimensional surface defects can be detected with high level of accuracy by this fast approach

Evaluation of nano-scale rotors and motors at static condition

The static performance of nano-scale rotor and the mechanical efficiency of micro rotors are important factors to evaluate rotary-wing NAVs. In this paper, two pairs of nano-scale rotors, which were formed with the same airfoil section for each pair, were compared to find the influence of chord distribution and twist distribution to rotor performance. A test bench was designed with highly sensitive mechanism systems in order to be able to measure the thrust and torque of nano-rotors accurately. The static performance of nanoscale rotors was evaluated experimentally with the test bench at ultra-low Re. And computations based on 3D unsteady incompressible Navier-Stokes solver with artificial compressibility were carried out as well to obtain the detailed flow field of nano rotor. It was found that the rotor figure of merit degraded a lot with size reduction. And the rotor solidity determined by chord distribution has a positive effect on the rotor thrust coefficient while pitch angle distribution influences the power coefficient. Flow field analysis indicated that the state of leading edge vortex might be the inherent reason of the difference of performance between rotors. The mechanical efficiency of several small motors were also compared which showed that the performance of small rotors decline with the reduction of size

Temperature-controlled electrospinning of EVOH nanofibre mats encapsulated with Ag, CuO, and ZnO particles for skin wound dressing

To treat skin burns, a new wound dressing, nanofibre mats with metal or metal oxide nanoparticles (Ag, CuO, and ZnO), was fabricated using the electrospinning technique. During a therapeutic process, the antibacterial ability and bio-compatibility of a new dressing material are of major concern. To expound the characteristics of ethylene vinyl alcohol (EVOH) nanofibre mats encapsulated with metal or metal oxide nanoparticles, denoted as Ag-EVOH, CuO-EVOH, and ZnO-EVOH, for use as new wound dressing materials, we investigated the suitable processing parameters to fabricate these materials, such as the voltage, tip-to-collector distance, concentration of the solution, and effect of environmental temperature. The antibacterial ability and bio-compatibility of Ag-EVOH, CuO-EVOH, and ZnO-EVOH were then tested and quantified. The outcomes show that the most suitable temperature for the fabrication of the materials is 40 °C (±3 °C). The antibacterial experiment results indicate that 0.08 g/ml of metal/metallic oxide shows the highest antibacterial ability toward Staphylococcus aureus. Furthermore, the largest diameters of the bacteriostatic loops of the three types of nanofibre mats, i.e. Ag-EVOH, CuO-EVOH, and ZnO-EVOH, are 5.89, 5.21, and 4.12 mm, respectively. Finally, the cell proliferations on the three nanofibre mats show a similar growth trend

Evaluation of meteorological drought and flood scenarios over Kenya, East Africa

This work examines drought and flood events over Kenya from 1981 to 2016 using the Standardized Precipitation–Evapotranspiration Index (SPEI). The spatiotemporal analysis of dry and wet events was conducted for 3 and 12 months. Extreme drought incidences were observed in the years 1987, 2000, 2006, and 2009 for SPEI-3, whilst the SPEI-12 demonstrated the manifestation of drought during the years 2000 and 2006. The SPEI showed that the wettest periods, 1997 and 1998, coincided with the El Nino event for both time steps. SPEI-3 showed a reduction in moderate drought events, while severe and extreme cases were on the increase tendencies towards the end of the twentieth century. Conversely, SPEI-12 depicted an overall increase in severe drought occurrence over the study location with ab observed intensity of −1.54 and a cumulative frequency of 64 months during the study period. Wet events showed an upward trend in the western and central highlands, while the rest of the regions showed an increase in dry events during the study period. Moreover, moderate dry/wet events predominated, whilst extreme events occurred least frequently across all grid cells. It is apparent that the study area experienced mild extreme dry events in both categories, although moderately severe dry events dominated most parts of the study area. A high intensity and frequency of drought was noted in SPEI-3, while the least occurrences of extreme events were recorded in SPEI-12. Though drought event prevailed across the study area, there was evidence of extreme flood conditions over the recent decades. These findings form a good basis for next step of research that will look at the projection of droughts over the study area based on regional climate models

Computationally Efficient Approximations Using Adaptive Weighting Coefficients for Solving Structural Optimization Problems

With rapid development of advanced manufacturing technologies and high demands for innovative lightweight constructions to mitigate the environmental and economic impacts, design optimization has attracted increasing attention in many engineering subjects, such as civil, structural, aerospace, automotive, and energy engineering. For nonconvex nonlinear constrained optimization problems with continuous variables, evaluations of the fitness and constraint functions by means of finite element simulations can be extremely expensive. To address this problem by algorithms with sufficient accuracy as well as less computational cost, an extended multipoint approximation method (EMAM) and an adaptive weighting-coefficient strategy are proposed to efficiently seek the optimum by the integration of metamodels with sequential quadratic programming (SQP). The developed EMAM stems from the principle of the polynomial approximation and assimilates the advantages of Taylor’s expansion for improving the suboptimal continuous solution. Results demonstrate the superiority of the proposed EMAM over other evolutionary algorithms (e.g., particle swarm optimization technique, firefly algorithm, genetic algorithm, metaheuristic methods, and other metamodeling techniques) in terms of the computational efficiency and accuracy by four well-established engineering problems. The developed EMAM reduces the number of simulations during the design phase and provides wealth of information for designers to effectively tailor the parameters for optimal solutions with computational efficiency in the simulation-based engineering optimization problems

Wild-Type and Non-Wild-Type Mycobacterium tuberculosis MIC Distributions for the Novel Fluoroquinolone Antofloxacin Compared with Those for Ofloxacin, Levofloxacin, and Moxifloxacin.

Antofloxacin (AFX) is a novel fluoroquinolone that has been approved in China for the treatment of infections caused by a variety of bacterial species. We investigated whether it could be repurposed for the treatment of tuberculosis by studying its in vitro activity. We determined the wild-type and non-wild-type MIC ranges for AFX as well as ofloxacin (OFX), levofloxacin (LFX), and moxifloxacin (MFX), using the microplate alamarBlue assay, of 126 clinical Mycobacterium tuberculosis strains from Beijing, China, of which 48 were OFX resistant on the basis of drug susceptibility testing on Löwenstein-Jensen medium. The MIC distributions were correlated with mutations in the quinolone resistance-determining regions of gyrA (Rv0006) and gyrB (Rv0005). Pharmacokinetic/pharmacodynamic (PK/PD) data for AFX were retrieved from the literature. AFX showed lower MIC levels than OFX but higher MIC levels than LFX and MFX on the basis of the tentative epidemiological cutoff values (ECOFFs) determined in this study. All strains with non-wild-type MICs for AFX harbored known resistance mutations that also resulted in non-wild-type MICs for LFX and MFX. Moreover, our data suggested that the current critical concentration of OFX for Löwenstein-Jensen medium that was recently revised by the World Health Organization might be too high, resulting in the misclassification of phenotypically non-wild-type strains with known resistance mutations as wild type. On the basis of our exploratory PK/PD calculations, the current dose of AFX is unlikely to be optimal for the treatment of tuberculosis, but higher doses could be effective.The work was supported by the research funding from Infectious Diseases Special Project, Minister of Health of China (2016ZX10003001-12) and Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (ZYLX201304). The strains used in this project were obtained from the ‘Beijing Bio-Bank of clinical resources on Tuberculosis’ (D09050704640000), Beijing Chest Hospital. In addition, this study was supported by the Health Innovation Challenge Fund (HICF-T5-342 and WT098600), a parallel funding partnership between the UK Department of Health and Wellcome Trust. T. S. was supported by grants from the Swedish Heart and Lung Foundation and Marianne and Marcus Wallenberg Foundation. The views expressed in this publication are those of the authors and not necessarily those of the Department of Health, Public Health England, or the Wellcome Trust. C. U. K. is a Junior Research Fellow at Wolfson College, Cambridge.This is the author accepted manuscript. The final version is available from American Society for Microbiology at http://dx.doi.org/10.1128/AAC.00393-16