A Secure Device Management Scheme with Audio-Based Location Distinction in IoT

Identifying a device and detecting a change in its position is critical for secure devices management in the Internet of Things(IoT).In this paper,a device management system is proposed to track the devices by using audio-based location distinction techniques.In the proposed scheme,traditional cryptographic techniques,such as symmetric encryption algorithm,RSA-based signcryption scheme,and audio-based secure transmission,are utilized to provide authentication,non-repudiation,and confidentiality in the information interaction of the management system.Moreover,an audio-based location distinction method is designed to detect the position change of the devices.Specifically,the audio frequency response(AFR)of several frequency points is utilized as a device signature.The device signature has the features as follows.(1)Hardware Signature:different pairs of speaker and microphone have different signatures;(2)Distance Signature:in the same direction,the signatures are different at different distances;and(3)Direction Signature:at the same distance,the signatures are different in different directions.Based on the features above,amovement detection algorithmfor device identification and location distinction is designed.Moreover,a secure communication protocol is also proposed by using traditional cryptographic techniques to provide integrity,authentication,and non-repudiation in the process of information interaction between devices,Access Points(APs),and Severs.Extensive experiments are conducted to evaluate the performance of the proposed method.The experimental results show that the proposedmethod has a good performance in accuracy and energy consumption.

Borehole stability in naturally fractured rocks with drilling mud intrusion and associated fracture strength weakening:A coupled DFN-DEM approach

Borehole instability in naturally fractured rocks poses significant challenges to drilling.Drilling mud invades the surrounding formations through natural fractures under the difference between the wellbore pressure(P w)and pore pressure(P p)during drilling,which may cause wellbore instability.However,the weakening of fracture strength due to mud intrusion is not considered in most existing borehole stability analyses,which may yield significant errors and misleading predictions.In addition,only limited factors were analyzed,and the fracture distribution was oversimplified.In this paper,the impacts of mud intrusion and associated fracture strength weakening on borehole stability in fractured rocks under both isotropic and anisotropic stress states are investigated using a coupled DEM(distinct element method)and DFN(discrete fracture network)method.It provides estimates of the effect of fracture strength weakening,wellbore pressure,in situ stresses,and sealing efficiency on borehole stability.The results show that mud intrusion and weakening of fracture strength can damage the borehole.This is demonstrated by the large displacement around the borehole,shear displacement on natural fractures,and the generation of fracture at shear limit.Mud intrusion reduces the shear strength of the fracture surface and leads to shear failure,which explains that the increase in mud weight may worsen borehole stability during overbalanced drilling in fractured formations.A higher in situ stress anisotropy exerts a significant influence on the mechanism of shear failure distribution around the wellbore.Moreover,the effect of sealing natural fractures on maintaining borehole stability is verified in this study,and the increase in sealing efficiency reduces the radial invasion distance of drilling mud.This study provides a directly quantitative prediction method of borehole instability in naturally fractured formations,which can consider the discrete fracture network,mud intrusion,and associated weakening of fracture strength.The information provided by the numerical approach(e.g.displacement around the borehole,shear displacement on fracture,and fracture at shear limit)is helpful for managing wellbore stability and designing wellbore-strengthening operations.

Numerical and theoretical study of large-scale failure of strata overlying sublevel caving mines with steeply dipping discontinuities

The deformation and fracture evolution mechanisms of the strata overlying mines mined using sublevel caving were studied via numerical simulations.Moreover,an expression for the normal force acting on the side face of a steeply dipping superimposed cantilever beam in the surrounding rock was deduced based on limit equilibrium theory.The results show the following:(1)surface displacement above metal mines with steeply dipping discontinuities shows significant step characteristics,and(2)the behavior of the strata as they fail exhibits superimposition characteristics.Generally,failure first occurs in certain superimposed strata slightly far from the goaf.Subsequently,with the constant downward excavation of the orebody,the superimposed strata become damaged both upwards away from and downwards toward the goaf.This process continues until the deep part of the steeply dipping superimposed strata forms a large-scale deep fracture plane that connects with the goaf.The deep fracture plane generally makes an angle of 12°-20°with the normal to the steeply dipping discontinuities.The effect of the constant outward transfer of strata movement due to the constant outward failure of the superimposed strata in the metal mines with steeply dipping discontinuities causes the scope of the strata movement in these mines to be larger than expected.The strata in the metal mines with steeply dipping discontinuities mainly show flexural toppling failure.However,the steeply dipping structural strata near the goaf mainly exhibit shear slipping failure,in which case the mechanical model used to describe them can be simplified by treating them as steeply dipping superimposed cantilever beams.By taking the steeply dipping superimposed cantilever beam that first experiences failure as the key stratum,the failure scope of the strata(and criteria for the stability of metal mines with steeply dipping discontinuities mined using sublevel caving)can be obtained via iterative computations from the key stratum,moving downward toward and upwards away from the goaf.

A Corpus-Driven Perspective on the Verb Valency Structure of Chinese EFL Learners:A Case Study of“Suggest”and“Advise”

This paper investigates the verb valency structure of English that is used by English as Foreign Language(EFL)learners from a corpus-driven perspective.Specifically,it focuses on the usage of the verbs“suggest”and“advise”in a selected corpus.By analyzing a sample of written and spoken texts,this study attempts to investigate the similarities and differences in the patterns of verb valency between native English speakers and Chinese EFL learners.The findings of this research can contribute to a better understanding of the challenges faced by Chinese EFL learners in acquiring accurate verb valency structures and provide insights for language teachers in designing effective pedagogical approaches.

Automatic identification of rock discontinuity and stability analysis of tunnel rock blocks using terrestrial laser scanning

Local geometric information and discontinuity features are key aspects of the analysis of the evolution and failure mechanisms of unstable rock blocks in rock tunnels.This study demonstrates the integration of terrestrial laser scanning(TLS)with distinct element method for rock mass characterization and stability analysis in tunnels.TLS records detailed geometric information of the surrounding rock mass by scanning and collecting the positions of millions of rock surface points without contact.By conducting a fuzzy K-means method,a discontinuity automatic identification algorithm was developed,and a method for obtaining the geometric parameters of discontinuities was proposed.This method permits the user to visually identify each discontinuity and acquire its spatial distribution features(e.g.occurrences,spac-ings,trace lengths)in great detail.Compared with hand mapping in conventional geotechnical surveys,the geometric information of discontinuities obtained by this approach is more accurate and the iden-tification is more efficient.Then,a discrete fracture network with the same statistical characteristics as the actual discontinuities was generated with the distinct element method,and a representative nu-merical model of the jointed surrounding rock mass was established.By means of numerical simulation,potential unstable rock blocks were assessed,and failure mechanisms were analyzed.This method was applied to detection and assessment of unstable rock blocks in the spillway and sand flushing tunnel of the Hongshiyan hydropower project after a collapse.The results show that the noncontact detection of blocks was more labor-saving with lower safety risks compared with manual surveys,and the stability assessment was more reliable since the numerical model built by this method was more consistent with the distribution characteristics of actual joints.This study can provide a reference for geological survey and unstable rock block hazard mitigation in tunnels subjected to complex geology and active rockfalls.

Effects of intermediate stress on deep rock strainbursts under true triaxial stresses

The effect of intermediate stress(in situ tunnel axial)on a strainburst is studied with a threedimensional(3D)bonded block distinct element method(DEM).A series of simulations of strainbursts under true triaxial in situ stress conditions(i.e.high tangential stress,moderate intermediate stress and low radial stress)of near-boundary rock masses are performed.Compared with the experimental results,the DEM model is able to capture the stress-strain response,failure pattern and energy balance of strainbursts.The fracturing processes of strainbursts are also numerically reproduced.Numerical results show that,as the intermediate stress increases:(1)The peak strain of strainbursts increases,the yield stress increases,the rock strength increases linearly,and the ratio of yield stress to rock strength decreases,indicating that the precursory information on strainbursts is enhanced;(2)Tensile and shear cracks increase significantly,and slabbing and bending of rock plates are more pronounced;and(3)The stored elastic strain energy and dissipated energy increase linearly,whereas the kinetic energy of the ejected rock fragments increases approximately exponentially,implying an increase in strainburst intensity.By comparing the experimental and numerical results,the effect of intermediate stress on the rock strength of strainbursts is discussed in order to address three key issues.Then,the Mogi criterion is applied to construct new strength criteria for strainbursts by converting the one-face free true triaxial stress state of a strainburst to its equivalent true triaxial stress state.In summary,the effect of intermediate stress on strainbursts is a double-edged sword that can enhance the rock strength and the precursory information of a strainburst,but also increase its intensity.

Investigation of long-wavelength elastic wave propagation through wet bentonite-filled rock joints

The saturation of the compacted bentonite buffer in the deep geological repository can cause bentonite swelling,intrusion into rock fractures,and erosion.Inevitably,erosion and subsequent bentonite mass loss due to groundwater inflow can aggravate the overall integrity of the engineered barrier system.Therefore,the coupled hydro-mechanical interaction between the buffer and rock during groundwater inflow and bentonite intrusion should be evaluated to guarantee the long-term safety of deep geological disposal.This study investigated the effect of bentonite erosion and intrusion on the elastic wave propagation characteristics in jointed rocks using a quasi-static resonant column test.Jointed rock specimens with different joint conditions(i.e.joint surface saturation and bentonite filling)were prepared using granite rock discs sampled from the Korea Underground Research Tunnel(KURT)and Gyeongju bentonite.The long-wavelength longitudinal and shear wave velocities were measured under different normal stress levels.A Hertzian-type power model was used to fit the wave velocities,and the relationship between the two fitted parameters provided the trend of joint conditions.Numerical simulations using three-dimensional distinct element code(3DEC)were conducted to better understand how the long-wavelength wave propagates through wet bentonite-filled rock joints.

Impact of ICTs on Core Competences of SMEs in Bukavu, DRC

Currently, it has been noticed a strong use of ICTs in several companies. The objective of this study was to analyze and measure the impact of the implementation of ICTs on the strategy and structure of management of core competence in SMEs in Bukavu, DRC. The scale used shows the good psychometric properties (χ2 = 75.045;P = 0.16;χ2/ddl = 1.471;CFI = 0.92;IFI = 0.92;RMSEA = 0.049;NFI = 0.79;GFI = 0.94;AGFI = 0.91. This study analyzed primary data collected from 195 SMEs in the city of Bukavu. Data processing was achieved using exploratory and confirmatory factor analysis and flat sorting. The results indicate that the use of ICTs by SME managers in the city of Bukavu has a positive impact on all dimensions of core competence selected in this study. They also reveal that the views of these leaders on the importance attached to the adoption of ICTs were divided and the level of ICT use was above average.

采动影响下山区地表裂隙发育通用离散单元法模拟研究

贵州响水煤矿3#煤层12309回采工作面停采后,离工作面较近地表未发现裂隙,远离工作面地表反而出现明显裂隙,针对这一现象,运用UDEC软件对12309采面进行了仿真数值模拟实验,通过模拟实验得到:采深172 m的开切眼前后出现两组裂隙,裂隙呈"V"字形;停采线处,水平离层裂隙和竖向破断裂隙贯通至地表冲沟;变坡面裂隙发育,稳定性差,会发生滑坡。

Genetic diversity and elite gene introgression reveal the japonica rice breeding in northern China

Abundant genetic diversity and rational population structure of germplasm benefit crop breeding greatly.To investigate genetic variation among geographically diverse set of japonica germplasm,we analyzed 233 japonica rice cultivars collected from Liaoning,Jilin and Heilongjiang provinces of China,which were released from 1970 to 2011 by using 62 simple sequence repeat（SSR） markers and 8 functional gene tags related to yield.A total of 195 alleles（N_a） were detected with an average of 3.61 per locus,indicating a low level of genetic diversity level among all individuals.The genetic diversity of the cultivars from Jilin Province was the highest among the three geographic distribution zones.Moreover,the genetic diversity was increased slightly with the released period of cultivars from 1970 to 2011.The analysis of molecular variance（AMOVA） revealed that genetic differentiation was more diverse within the populations than that among the populations.The neighbor-joining（NJ） tree indicated that cultivar clusters based on geographic distribution represented three independent groups,among which the cluster of cultivars from Heilongjiang is distinctly different to the cluster of cultivars from Liaoning.For the examined functional genes,two or three allelic variations for each were detected,except for IPA1 and GW2,and most of elite genes had been introgressed in modem japonica rice varieties.These results provide a valuable evaluation for genetic backgrounds of current japonica rice and will be used directly for japonica rice breeding in future.

Research on Development Strategies of Small Towns and Villages under the Background of New Countryside Construction —A Case Study of Bixi Town of Changshu City of Jiangsu Province in China

By taking Bixi Town of Changshu City of Jiangsu Province in China for example,through the analysis of its development including villages types,industrial layout and existing problems,development strategies for basic facilities in villages of Bixi Town have been illustrated from the perspective of road system,water supply and drainage system,power supply engineer,communication facilities,cable television engineer and sanitation engineer.Strategies contain building famous historical and cultural villages,developing leisure agriculture and developing distinctive agricultural undertakings.It is expected to provide development strategies for small towns and villages under the background of new countryside construction.

FOREWORD

It has been confirmed that climatic anomaly influenced human life and production andeven causes disasters. With the economic activity developing in the world,the influence isbecoming more and more greater.Scientists have long been devoting themselves to the studyof the cause of climatic anomaly. Now they distinctly attribute the cause to the ocean,where life originated from.Numerous observatons have confirmed that El Nino,known

STUDY ON THE RESPONSE OF THE D-REGION OF THE IONOSPHERE TO THE SOLAR BURSTS

1.Introduction The measurements of the time delay(phase)and field strength of Loran—C100kHz sky—wave signal(transmitting station:26°36′N,128°09′E,2006kmfrom Lintong)were continuously conducted at Lintong(34°22′N,109°13′E)

Analysis on Competitiveness of Lingnan Distinctive Architectural Tourist Cultural Sites in Guangdong Province Based on GIS

By using multi-objective analysis method, five architectural tourist sites with Lingnan characteristics were selected. Through the analysis on relevant data obtained by GIS, spatial analysis research had been conducted on competitiveness of Lingnan distinctive architectural tourist cultural sites in Guangdong Province and some conclusions had been obtained.

AR5629:A SUPER FLARE ON 16 AUG.,1989(Abstract)

On 16 August,1989,in the space above the active region 5629(S16W96)a X20X—ray flare was produced.It lasted for 13 hours and its X—ray storm was the largest onein the solar X—ray observation record.We observed it with using the Chromospheric HαMonitor equiped in the Two—dimensional Multi—band Solar Spectrograph at

A Brief Account of Independent College in China:Its Past and Further Development

This article briefs the past and development of independent colleges until now in China,dealing with the reasons why they have come into existence and developed in a remarkable way.A somewhat detailed analysis of their distinctions from other higher education has been made and the further development strategies are also presented in it.

On the Contrastive Analysis between China English and Chinglish

The paper attempts to make the distinction between China English and Chinglish from the different aspects,to understandmore about the relationship of them and reasons of their occurrences.With a synthesizing and comparative method,the study draws aclear cut between China English and Chinglish and explores their implications to EFL in China.

12.4.Colon,rectum and anus

930312 Test of colonic transit for the diagno-sis of constipation.LIU Shixin (刘世信),et al.Binjiang Hosp Tianjin,300022.Natl Med J China 1993;73(2)75—77.This study consists of the design of the ex-perimental markers for the colonic transit andthe application to clinical examination.Themarkers were displayed distinctly in the transittest.The study of clinical application showedthat colonic transit test is of diagnostic value inscreening patients with constipation.The indexof transit test,an authoritatively significant tar-get.has an imnortant valuta for the

地下水封石油洞库工程的灌浆参数模拟分析

以某深埋地下水封石油洞库为研究对象,针对裂隙岩体,采用离散单元法,选用UDEC软件,将浆液设定为宾汉姆流体模型,研究了各灌浆参数的变化对浆液渗透范围的影响。研究结果表明:增大灌浆压力,浆液的渗透范围显著增大,但在高灌浆压力阶段,更多的灌浆压力用于克服围岩的变形;岩体裂隙越密,浆液的渗透范围越大,但变化不明显;增加裂隙隙宽,浆液的渗透范围不断增加,最后趋向平稳;增加浆液的动力黏度,浆液的渗透范围不断减小,最后趋向平稳。

Taxonomic Distinctness of Macrofauna as an Ecological Indicator in Laizhou Bay and Adjacent Waters

In this paper, we assessed the ecological and biodiversity status in the Bohai Sea through a quantitative survey on mac-rofaunal community at 25 stations in Laizhou Bay and adjacent waters in the autumn of 2006.We tested the robustness and effectiveness of taxonomic distinctness as an ecological indictor by analyzing its correlation with species richness and natural environmental variables and by analyzing other ecological indicators (Shannon-Wiener H' and W statistics from Abundance Biomass Comparison curve).Results so obtained indicated that the benthic environment of the study waters in general is not under major impact of anthropogenic disturbance, but some stations in Laizhou Bay and along the coast of the Shandong Peninsula and even in the central Bohai Sea might be moderately disturbed and showed signs of ecological degradation.The taxonomic distinctness measures △+ and Λ+ were independent of sampling effort and natural environment factors and were compliant to other ecological indicators.Further application of the taxonomic distinctness indicator to assess marine biodiversity and ecosystem health on a larger regional scale with historical data seems promising.