With the maturity and development of 5G field,Mobile Edge CrowdSensing(MECS),as an intelligent data collection paradigm,provides a broad prospect for various applications in IoT.However,sensing users as data uploaders...With the maturity and development of 5G field,Mobile Edge CrowdSensing(MECS),as an intelligent data collection paradigm,provides a broad prospect for various applications in IoT.However,sensing users as data uploaders lack a balance between data benefits and privacy threats,leading to conservative data uploads and low revenue or excessive uploads and privacy breaches.To solve this problem,a Dynamic Privacy Measurement and Protection(DPMP)framework is proposed based on differential privacy and reinforcement learning.Firstly,a DPM model is designed to quantify the amount of data privacy,and a calculation method for personalized privacy threshold of different users is also designed.Furthermore,a Dynamic Private sensing data Selection(DPS)algorithm is proposed to help sensing users maximize data benefits within their privacy thresholds.Finally,theoretical analysis and ample experiment results show that DPMP framework is effective and efficient to achieve a balance between data benefits and sensing user privacy protection,in particular,the proposed DPMP framework has 63%and 23%higher training efficiency and data benefits,respectively,compared to the Monte Carlo algorithm.展开更多
This paper investigates the estimation problem for a spatially distributed process described by a partial differential equation with missing measurements.The randomly missing measurements are introduced in order to be...This paper investigates the estimation problem for a spatially distributed process described by a partial differential equation with missing measurements.The randomly missing measurements are introduced in order to better reflect the reality in the sensor network.To improve the estimation performance for the spatially distributed process,a network of sensors which are allowed to move within the spatial domain is used.We aim to design an estimator which is used to approximate the distributed process and the mobile trajectories for sensors such that,for all possible missing measurements,the estimation error system is globally asymptotically stable in the mean square sense.By constructing Lyapunov functionals and using inequality analysis,the guidance scheme of every sensor and the convergence of the estimation error system are obtained.Finally,a numerical example is given to verify the effectiveness of the proposed estimator utilizing the proposed guidance scheme for sensors.展开更多
Measuring mobile calls data is an increasingly import issue,which will benefit to the understanding of the behavior of mobile users and assist telecom operators to optimize their business strategies.The existing resea...Measuring mobile calls data is an increasingly import issue,which will benefit to the understanding of the behavior of mobile users and assist telecom operators to optimize their business strategies.The existing researches on cell phone data measurement only focus on mobile calls or on mobile-internet surfing and little researches focus on the interactions of behaviors between them.In this paper,some basic factors of the association between mobile calls and mobile-internet surfing are measured.Then first their distributions are compared and the preference of users is quantified.After that experiments on the curve fitting of both the whole and parts of these distributions are done.Through the comparison of the correlation coefficients and Fourier fitting parameters,different behaviors is found between workdays and weekends,as well as Saturdays and Sundays in mobile-call distributions.Besides,the results of our observation show that the mobile-internet traffic does not always monotone increase with the increase of online time,significant changes are observed after 8hours of mobile-internet surfing.展开更多
Single-camera mobile-vision coordinate measurement is one of the primary methods of 3D-coordinate vision measurement, and coded target plays an important role in this system. A multifunctional coded target and its rec...Single-camera mobile-vision coordinate measurement is one of the primary methods of 3D-coordinate vision measurement, and coded target plays an important role in this system. A multifunctional coded target and its recognition algorithm is developed, which can realize automatic match of feature points, calculation of camera initial exterior orientation and space scale factor constraint in measurement system. The uniqueness and scalability of coding are guaranteed by the rational arrangement of code bits. The recognition of coded targets is realized by cross-ratio invariance restriction, space coordinates transform of feature points based on spacial pose estimation algorithm, recognition of code bits and computation of coding values. The experiment results demonstrate the uniqueness of the coding form and the reliability of recognition.展开更多
Based on mobile devices as a solution for measurement faces interesting challenges, which involve poor human- computer interaction and limited computer capability. In this paper, we present the mobile sensing system ...Based on mobile devices as a solution for measurement faces interesting challenges, which involve poor human- computer interaction and limited computer capability. In this paper, we present the mobile sensing system (MSS) with func- tions of constructing, configuring and implementing measurement applications. MSS consists of a mobile device and a sensor probe, In the mobile device we install a pocket virtual instrument platform (PVIP), which has object-oriented software ar- chitecture and can be configured through extensible markup language (XML) files. And these configuration files can be written to the probe. Therefore, the probe can produce the measurement of APP in the mobile device. This infrastructure has been illustrated by a sound signal acquisition task and a flexible force measurement task which are finished with an android smartphone and a probe. These examples suggest that MSS is reconfigurable, highly automatical and flexible.展开更多
When associating data from various sensors to estimate the posture of mobile robots, a crucial problem to be solved is that there may be some delayed measurements. Furthermore, the general multi-sensor data fusion alg...When associating data from various sensors to estimate the posture of mobile robots, a crucial problem to be solved is that there may be some delayed measurements. Furthermore, the general multi-sensor data fusion algorithm is a Kalman filter. In order to handle the problem concerning delayed measurements, this paper investigates a Kalman filter modified to account for the delays. Based on the interpolating measurement, a fusion system is applied to estimate the posture of a mobile robot which fuses the data from the encoder and laser global position system using the extended Kalman filter algorithm. Finally, the posture estimation experiment of the mobile robot is given whose result verifies the feasibility and efficiency of the algorithm.展开更多
We report the direct measurements of conductivity and mobility in millimeter-sized single-crystalline graphene on SiO2/Si via van der Pauw geometry by using a home-designed four-probe scanning tunneling microscope(4P...We report the direct measurements of conductivity and mobility in millimeter-sized single-crystalline graphene on SiO2/Si via van der Pauw geometry by using a home-designed four-probe scanning tunneling microscope(4P-STM). The gate-tunable conductivity and mobility are extracted from standard van der Pauw resistance measurements where the four STM probes contact the four peripheries of hexagonal graphene flakes, respectively. The high homogeneity of transport properties of the single-crystalline graphene flake is confirmed by comparing the extracted conductivities and mobilities from three setups with different geometry factors. Our studies provide a reliable solution for directly evaluating the entire electrical properties of graphene in a non-invasive way and could be extended to characterizing other two-dimensional materials.展开更多
The significance and research status of tooth mobility (TM) measurement are introduced. There are many methods to measure the TM, but up to now no one does vivo dynamic TM measurement. An optical-electronic method is ...The significance and research status of tooth mobility (TM) measurement are introduced. There are many methods to measure the TM, but up to now no one does vivo dynamic TM measurement. An optical-electronic method is raised to measure it in this paper. The measurement theory is introduced and a measurement system is setup. Special proceeding is done for this measurement because of the small oral cavity measurement area. It is the first time to get vivo dynamic TM measurement result at last. The measurement result is analysed and a new movement period is discovered. It shows that this method satisfies for the dynamical tooth movement. Further research is suggested.展开更多
Based on the measurement mechanism of mobility in pressure measurement while drilling, through analyzing a large number of mobility data, it is found that under the condition of water-based mud drilling, the product o...Based on the measurement mechanism of mobility in pressure measurement while drilling, through analyzing a large number of mobility data, it is found that under the condition of water-based mud drilling, the product of mobility from pressure measurement while drilling and the viscosity of mud filtrate is infinitely close to the water phase permeability under the residual oil in relative permeability experiment. Based on this, a method converting the mobility from pressure measurement while drilling to core permeability is proposed, and the permeability based on Timur formula has been established. Application of this method in Penglai 19-9 oilfield of Bohai Sea shows:(1) Compared with the permeability calculated by the model of adjacent oilfields, the permeability calculated by this model is more consistent with the permeability calculated by core analysis.(2) Based on the new model, the correlation between the calculated mobility of well logging and the actual drilling specific productivity index bas been established. Compared with the relationship established by using the permeability model of an adjacent oilfield, the correlation of the new model is better.(3) Productivity of four directional wells was predicted, and the prediction results are in good agreement with the actual production after drilling.展开更多
There is an increasing demand on wireless communications in subway tunnels to provide video surveillance and sensory data for security,maintenance and train control,and to offer various communication or entertainment ...There is an increasing demand on wireless communications in subway tunnels to provide video surveillance and sensory data for security,maintenance and train control,and to offer various communication or entertainment services(e.g.,Internet,etc.) to passengers as well.The wireless channel in tunnels is quite unique due to the confined space and the waveguide effects.Therefore,modeling the radio channel characteristics in tunnels is critically important for communication systems design or optimization.This paper investigates the key radio channel characteristics of a subway tunnel at 2.4 GHz and 5 GHz,such as the path loss,root mean square(RMS) delay spread,channel stationarity,Doppler shift,and channel capacity.The field measurements show that channel characteristics in tunnels are highly location-dependent and there exist abundant components in Doppler shift domain.In the straight section of the subway tunnel,the measured path loss exponents are close to1.6,lower than that in free space.展开更多
The ability of accurate and scalable mobile device recognition is critically important for mobile network operators and ISPs to understand their customers' behaviours and enhance their user experience.In this pape...The ability of accurate and scalable mobile device recognition is critically important for mobile network operators and ISPs to understand their customers' behaviours and enhance their user experience.In this paper,we propose a novel method for mobile device model recognition by using statistical information derived from large amounts of mobile network traffic data.Specifically,we create a Jaccardbased coefficient measure method to identify a proper keyword representing each mobile device model from massive unstructured textual HTTP access logs.To handle the large amount of traffic data generated from large mobile networks,this method is designed as a set of parallel algorithms,and is implemented through the MapReduce framework which is a distributed parallel programming model with proven low-cost and high-efficiency features.Evaluations using real data sets show that our method can accurately recognise mobile client models while meeting the scalability and producer-independency requirements of large mobile network operators.Results show that a 91.5% accuracy rate is achieved for recognising mobile client models from 2 billion records,which is dramatically higher than existing solutions.展开更多
Gives a new technique to measure the dynamic deformation behavior and strain development of a hollow steel projectile during its penetration of concrete targets. Direct strain measurement was performed by applying str...Gives a new technique to measure the dynamic deformation behavior and strain development of a hollow steel projectile during its penetration of concrete targets. Direct strain measurement was performed by applying strain gages attached to the inner walls of the hollow projectile, linked with on-board testing and storage recorder. This on-board test-record system is easy to operate, cost-effective and can provide reasonable, accurate and detailed information. Obverse ballistic experiments were carried out on ogival-nose hollow projectiles normally impacting concrete targets at velocities from 150 m/s to 300 m/s. The deformation process of projectiles was measured, recorded and played back. Profiles of voltage-time relationship were successively obtained and transfered to strain-time relationship with the aid of calibration tables. It was found that projectiles go through a series of compression and tension deformations intermittently. Relationships between strain development and projectile deformation process were discussed.展开更多
Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organi...Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organic aerosols(SOA).In recent years,there have been intensive studies covering MAHs emission from various sources and their behavior under stimulated photochemical conditions.Yet in-situ measurements of PAHs presence and variations in ambient air are sparse.Herein we conducted large geometrical scale mobile measurements for 16 aromatic hydrocarbons(AHs,including 7 MAHs and 9 PAHs)in eastern China between October 27 and November 8,2019.This unique dataset has allowed for some insights in terms of AHs concentration variations,accompanying chemical composition,source contributions and spatial distributions in eastern China.In general,AHs showed a clear concentration variability between the south and the north of the Yangtze River Delta(YRD).The concentrations of PAHs were approximately 9%of AHs,but contributed 23%of SOA formation potential.Source apportionment via positive matrix factorization(PMF)model revealed that industrial processes as the largest source(44%)of observed AHs,followed by solvent usage(21%),vehicle exhaust(19%),coal combustion(11%)and coking processes(6%).In the perspective of PAHs sources,coal combustion emissions were identified as the dominating factor of a share of 41%–52%in eastern China.Our findings complemented the simultaneously monitoring information of PAHs and MAHs in eastern China,revealed the importance of PAHs to SOA formation and highlighted the necessity of formulating strategies to reduce emissions from anthropogenic sources and reduce risks to human health.展开更多
In this paper, a probabilistic fuzzy approach is proposed for mobile-robot reactive navigation using range sensors. The primary motivation is an integrated reactive navigation control system with good real-time perfor...In this paper, a probabilistic fuzzy approach is proposed for mobile-robot reactive navigation using range sensors. The primary motivation is an integrated reactive navigation control system with good real-time performance under uncertainty. To accomplish this aim, a probabilistic fuzzy logic system (PFLS) is introduced to range measurement and reactive navigation in local environments. PFLS is first adopted to handle the fuzzy and stochastic uncertainties in range sensors and to provide more precise distance information in unknown environments. Consequently these sensor data are sent to a probabilistic fuzzy rule-based inference system with reactive behaviors for local navigation. The feasibility and effectiveness of the proposed approach are verified by simulation and the experiments on a real mobile robot.展开更多
A mobile system comprising of a Geiger-Muller (GM) dosimeter connected with a smart phone was used for ambient gamma dose rate survey within the districts and on the roads within the state of Kuwait. While the dosimet...A mobile system comprising of a Geiger-Muller (GM) dosimeter connected with a smart phone was used for ambient gamma dose rate survey within the districts and on the roads within the state of Kuwait. While the dosimeter provides data on gamma dose rates, the smart phone provides the GPS navigation information and saves the data for subsequent analysis and mapping. The survey covered a total distance of about 2300 km within the country and 3117 data points were recorded to show the dose rate distribution on the map of Kuwait. The results show that the ambient dose rates in Kuwait range from 40 to 180 nSv.h-1 with a mean value of 103 nSv.h-1. The dosimetric system described has good potential as a tool for determining baseline background radiation dose rates in an area.展开更多
Wireless sensor networks have been identified as one of the key technologies for the 21st century. In order to overcome their limitations such as fault tolerance and conservation of energy, we propose a middleware sol...Wireless sensor networks have been identified as one of the key technologies for the 21st century. In order to overcome their limitations such as fault tolerance and conservation of energy, we propose a middleware solution, In-Motes. In-Motes stands as a fault tolerant platform for deploying and monitoring applications in real time offers a number of possibilities for the end user giving him in parallel the freedom to experiment with various parameters, in an effort the deployed applications to run in an energy efficient manner inside the network. The proposed scheme is evaluated through the In-Motes EYE application, aiming to test its merits under real time conditions. In-Motes EYE application which is an agent based real time In-Motes application developed for sensing acceleration variations in an environment. The application was tested in a prototype area, road alike, for a period of four months.展开更多
Data evaluation strategies for the novel coupled MCC-IMS sensory system are developed. Mayor attention to the plausibility of applied procedures and the feasibility of automation was paid. Three stages of extraction l...Data evaluation strategies for the novel coupled MCC-IMS sensory system are developed. Mayor attention to the plausibility of applied procedures and the feasibility of automation was paid. Three stages of extraction levels with increasing data reduction are presented for several fields of application. According to suitable extraction levels, real data were tested on various structures of artificial neural networks (ANN) with the result, that the computational levels must still be chosen by expertise, but subsequent processing and training can be fully automated. For the training of larger net- works a method of automated generation of secondary training data is presented which exceeds the quality of previous noise models by far. It is concluded that the combination of MCC-IMS as measuring instrument and ANNs as evalua- tion technique have high potential for industrial use in process monitoring.展开更多
Noise measurement using mobile phones is now developed very well. While there are some good applications for the measurement of noise from road traffic, thus on processing of measured data is only paid a very little a...Noise measurement using mobile phones is now developed very well. While there are some good applications for the measurement of noise from road traffic, thus on processing of measured data is only paid a very little attention. The data, however, are burdened by specific errors and for further work with them it is necessary to adjust and determine their uncertainty. One of the biggest problems is inaccuracy in position versus the noise source and the shortest length of measurement that can be regarded as representative. Imprecision in terms of location can be determined by calculating the variance of possible distance from the noise source, which for measurement of traffic noise requires a map-matching data points both transverse to the street (sidewalk) network and in the longwise direction. During typical urban measurements, this error can even reach 7 - 10 dB. Three basic types of algorithms for the calculation of uncertainty and positional correction based on the type of input and output data (raster, vector, vector-oriented) were tested. Uncertainty in the variability of the measurement data is necessary to determine from the number of passing vehicles per time unit. The presented solutions are implemented in the Mobile Noise system.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant U1905211,Grant 61872088,Grant 62072109,Grant 61872090,and Grant U1804263in part by the Guangxi Key Laboratory of Trusted Software under Grant KX202042+3 种基金in part by the Science and Technology Major Support Program of Guizhou Province under Grant 20183001in part by the Science and Technology Program of Guizhou Province under Grant 20191098in part by the Project of High-level Innovative Talents of Guizhou Province under Grant 20206008in part by the Open Research Fund of Key Laboratory of Cryptography of Zhejiang Province under Grant ZCL21015.
文摘With the maturity and development of 5G field,Mobile Edge CrowdSensing(MECS),as an intelligent data collection paradigm,provides a broad prospect for various applications in IoT.However,sensing users as data uploaders lack a balance between data benefits and privacy threats,leading to conservative data uploads and low revenue or excessive uploads and privacy breaches.To solve this problem,a Dynamic Privacy Measurement and Protection(DPMP)framework is proposed based on differential privacy and reinforcement learning.Firstly,a DPM model is designed to quantify the amount of data privacy,and a calculation method for personalized privacy threshold of different users is also designed.Furthermore,a Dynamic Private sensing data Selection(DPS)algorithm is proposed to help sensing users maximize data benefits within their privacy thresholds.Finally,theoretical analysis and ample experiment results show that DPMP framework is effective and efficient to achieve a balance between data benefits and sensing user privacy protection,in particular,the proposed DPMP framework has 63%and 23%higher training efficiency and data benefits,respectively,compared to the Monte Carlo algorithm.
基金supported by the National Natural Science Foundation of China(Grant Nos.61174021,61473136,and 61104155)the 111 Project(Grant No.B12018)
文摘This paper investigates the estimation problem for a spatially distributed process described by a partial differential equation with missing measurements.The randomly missing measurements are introduced in order to better reflect the reality in the sensor network.To improve the estimation performance for the spatially distributed process,a network of sensors which are allowed to move within the spatial domain is used.We aim to design an estimator which is used to approximate the distributed process and the mobile trajectories for sensors such that,for all possible missing measurements,the estimation error system is globally asymptotically stable in the mean square sense.By constructing Lyapunov functionals and using inequality analysis,the guidance scheme of every sensor and the convergence of the estimation error system are obtained.Finally,a numerical example is given to verify the effectiveness of the proposed estimator utilizing the proposed guidance scheme for sensors.
基金Supported by the National High Technology Research and Development Programme of China(No.2011AA010706)the National Natural Science Foundation of China(No.61170041)
文摘Measuring mobile calls data is an increasingly import issue,which will benefit to the understanding of the behavior of mobile users and assist telecom operators to optimize their business strategies.The existing researches on cell phone data measurement only focus on mobile calls or on mobile-internet surfing and little researches focus on the interactions of behaviors between them.In this paper,some basic factors of the association between mobile calls and mobile-internet surfing are measured.Then first their distributions are compared and the preference of users is quantified.After that experiments on the curve fitting of both the whole and parts of these distributions are done.Through the comparison of the correlation coefficients and Fourier fitting parameters,different behaviors is found between workdays and weekends,as well as Saturdays and Sundays in mobile-call distributions.Besides,the results of our observation show that the mobile-internet traffic does not always monotone increase with the increase of online time,significant changes are observed after 8hours of mobile-internet surfing.
文摘Single-camera mobile-vision coordinate measurement is one of the primary methods of 3D-coordinate vision measurement, and coded target plays an important role in this system. A multifunctional coded target and its recognition algorithm is developed, which can realize automatic match of feature points, calculation of camera initial exterior orientation and space scale factor constraint in measurement system. The uniqueness and scalability of coding are guaranteed by the rational arrangement of code bits. The recognition of coded targets is realized by cross-ratio invariance restriction, space coordinates transform of feature points based on spacial pose estimation algorithm, recognition of code bits and computation of coding values. The experiment results demonstrate the uniqueness of the coding form and the reliability of recognition.
基金The Ministry of Science and Technology of the People's Republic of China,Within the Framework of the Project the CNC Products innovation demonstration(No.2012BAF13B06)
文摘Based on mobile devices as a solution for measurement faces interesting challenges, which involve poor human- computer interaction and limited computer capability. In this paper, we present the mobile sensing system (MSS) with func- tions of constructing, configuring and implementing measurement applications. MSS consists of a mobile device and a sensor probe, In the mobile device we install a pocket virtual instrument platform (PVIP), which has object-oriented software ar- chitecture and can be configured through extensible markup language (XML) files. And these configuration files can be written to the probe. Therefore, the probe can produce the measurement of APP in the mobile device. This infrastructure has been illustrated by a sound signal acquisition task and a flexible force measurement task which are finished with an android smartphone and a probe. These examples suggest that MSS is reconfigurable, highly automatical and flexible.
文摘When associating data from various sensors to estimate the posture of mobile robots, a crucial problem to be solved is that there may be some delayed measurements. Furthermore, the general multi-sensor data fusion algorithm is a Kalman filter. In order to handle the problem concerning delayed measurements, this paper investigates a Kalman filter modified to account for the delays. Based on the interpolating measurement, a fusion system is applied to estimate the posture of a mobile robot which fuses the data from the encoder and laser global position system using the extended Kalman filter algorithm. Finally, the posture estimation experiment of the mobile robot is given whose result verifies the feasibility and efficiency of the algorithm.
基金supported by the Science Fund from the Ministry of Science and Technology of China(Grant No.2013CBA01600)the National Key Research&Development Project of China(Grant No.2016YFA0202300)+1 种基金the National Natural Science Foundation of China(Grant Nos.61474141,61674170,61335006,61390501,51325204,and 51210003)the Chinese Academy of Sciences(CAS) and Youth Innovation Promotion Association of CAS(Grant No.20150005)
文摘We report the direct measurements of conductivity and mobility in millimeter-sized single-crystalline graphene on SiO2/Si via van der Pauw geometry by using a home-designed four-probe scanning tunneling microscope(4P-STM). The gate-tunable conductivity and mobility are extracted from standard van der Pauw resistance measurements where the four STM probes contact the four peripheries of hexagonal graphene flakes, respectively. The high homogeneity of transport properties of the single-crystalline graphene flake is confirmed by comparing the extracted conductivities and mobilities from three setups with different geometry factors. Our studies provide a reliable solution for directly evaluating the entire electrical properties of graphene in a non-invasive way and could be extended to characterizing other two-dimensional materials.
基金The CAS fund for choosing excellent student abroad going back China to work(2 0 0 10 5 130 935 0 9)
文摘The significance and research status of tooth mobility (TM) measurement are introduced. There are many methods to measure the TM, but up to now no one does vivo dynamic TM measurement. An optical-electronic method is raised to measure it in this paper. The measurement theory is introduced and a measurement system is setup. Special proceeding is done for this measurement because of the small oral cavity measurement area. It is the first time to get vivo dynamic TM measurement result at last. The measurement result is analysed and a new movement period is discovered. It shows that this method satisfies for the dynamical tooth movement. Further research is suggested.
基金Supported by the China National Science and Technology Major Project(2016ZX058-001)the CNOOC Scientific and Technological Project(CNOOC-KJ135-ZDXM36-TJ).
文摘Based on the measurement mechanism of mobility in pressure measurement while drilling, through analyzing a large number of mobility data, it is found that under the condition of water-based mud drilling, the product of mobility from pressure measurement while drilling and the viscosity of mud filtrate is infinitely close to the water phase permeability under the residual oil in relative permeability experiment. Based on this, a method converting the mobility from pressure measurement while drilling to core permeability is proposed, and the permeability based on Timur formula has been established. Application of this method in Penglai 19-9 oilfield of Bohai Sea shows:(1) Compared with the permeability calculated by the model of adjacent oilfields, the permeability calculated by this model is more consistent with the permeability calculated by core analysis.(2) Based on the new model, the correlation between the calculated mobility of well logging and the actual drilling specific productivity index bas been established. Compared with the relationship established by using the permeability model of an adjacent oilfield, the correlation of the new model is better.(3) Productivity of four directional wells was predicted, and the prediction results are in good agreement with the actual production after drilling.
基金supported in part by the NSFC project under grant No.61132003the Fundamental Research Funds for the Central Universities(2013JBZ002)the Ph.D.Program Foundation of Ministry of Education of China under grant No.20120009130002
文摘There is an increasing demand on wireless communications in subway tunnels to provide video surveillance and sensory data for security,maintenance and train control,and to offer various communication or entertainment services(e.g.,Internet,etc.) to passengers as well.The wireless channel in tunnels is quite unique due to the confined space and the waveguide effects.Therefore,modeling the radio channel characteristics in tunnels is critically important for communication systems design or optimization.This paper investigates the key radio channel characteristics of a subway tunnel at 2.4 GHz and 5 GHz,such as the path loss,root mean square(RMS) delay spread,channel stationarity,Doppler shift,and channel capacity.The field measurements show that channel characteristics in tunnels are highly location-dependent and there exist abundant components in Doppler shift domain.In the straight section of the subway tunnel,the measured path loss exponents are close to1.6,lower than that in free space.
基金supported in part by the National Natural Science Foundation of China under Grant No.61072061the National Science and Technology Major Projects under Grant No.2012ZX03002008the Fundamental Research Funds for the Central Universities under Grant No.2012RC0121
文摘The ability of accurate and scalable mobile device recognition is critically important for mobile network operators and ISPs to understand their customers' behaviours and enhance their user experience.In this paper,we propose a novel method for mobile device model recognition by using statistical information derived from large amounts of mobile network traffic data.Specifically,we create a Jaccardbased coefficient measure method to identify a proper keyword representing each mobile device model from massive unstructured textual HTTP access logs.To handle the large amount of traffic data generated from large mobile networks,this method is designed as a set of parallel algorithms,and is implemented through the MapReduce framework which is a distributed parallel programming model with proven low-cost and high-efficiency features.Evaluations using real data sets show that our method can accurately recognise mobile client models while meeting the scalability and producer-independency requirements of large mobile network operators.Results show that a 91.5% accuracy rate is achieved for recognising mobile client models from 2 billion records,which is dramatically higher than existing solutions.
文摘Gives a new technique to measure the dynamic deformation behavior and strain development of a hollow steel projectile during its penetration of concrete targets. Direct strain measurement was performed by applying strain gages attached to the inner walls of the hollow projectile, linked with on-board testing and storage recorder. This on-board test-record system is easy to operate, cost-effective and can provide reasonable, accurate and detailed information. Obverse ballistic experiments were carried out on ogival-nose hollow projectiles normally impacting concrete targets at velocities from 150 m/s to 300 m/s. The deformation process of projectiles was measured, recorded and played back. Profiles of voltage-time relationship were successively obtained and transfered to strain-time relationship with the aid of calibration tables. It was found that projectiles go through a series of compression and tension deformations intermittently. Relationships between strain development and projectile deformation process were discussed.
基金supported by the National Natural Science Foundation of China(No.42175135)the Science and Technology Commission of the Shanghai Municipality(No.20ZR1447800).
文摘Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organic aerosols(SOA).In recent years,there have been intensive studies covering MAHs emission from various sources and their behavior under stimulated photochemical conditions.Yet in-situ measurements of PAHs presence and variations in ambient air are sparse.Herein we conducted large geometrical scale mobile measurements for 16 aromatic hydrocarbons(AHs,including 7 MAHs and 9 PAHs)in eastern China between October 27 and November 8,2019.This unique dataset has allowed for some insights in terms of AHs concentration variations,accompanying chemical composition,source contributions and spatial distributions in eastern China.In general,AHs showed a clear concentration variability between the south and the north of the Yangtze River Delta(YRD).The concentrations of PAHs were approximately 9%of AHs,but contributed 23%of SOA formation potential.Source apportionment via positive matrix factorization(PMF)model revealed that industrial processes as the largest source(44%)of observed AHs,followed by solvent usage(21%),vehicle exhaust(19%),coal combustion(11%)and coking processes(6%).In the perspective of PAHs sources,coal combustion emissions were identified as the dominating factor of a share of 41%–52%in eastern China.Our findings complemented the simultaneously monitoring information of PAHs and MAHs in eastern China,revealed the importance of PAHs to SOA formation and highlighted the necessity of formulating strategies to reduce emissions from anthropogenic sources and reduce risks to human health.
文摘In this paper, a probabilistic fuzzy approach is proposed for mobile-robot reactive navigation using range sensors. The primary motivation is an integrated reactive navigation control system with good real-time performance under uncertainty. To accomplish this aim, a probabilistic fuzzy logic system (PFLS) is introduced to range measurement and reactive navigation in local environments. PFLS is first adopted to handle the fuzzy and stochastic uncertainties in range sensors and to provide more precise distance information in unknown environments. Consequently these sensor data are sent to a probabilistic fuzzy rule-based inference system with reactive behaviors for local navigation. The feasibility and effectiveness of the proposed approach are verified by simulation and the experiments on a real mobile robot.
文摘A mobile system comprising of a Geiger-Muller (GM) dosimeter connected with a smart phone was used for ambient gamma dose rate survey within the districts and on the roads within the state of Kuwait. While the dosimeter provides data on gamma dose rates, the smart phone provides the GPS navigation information and saves the data for subsequent analysis and mapping. The survey covered a total distance of about 2300 km within the country and 3117 data points were recorded to show the dose rate distribution on the map of Kuwait. The results show that the ambient dose rates in Kuwait range from 40 to 180 nSv.h-1 with a mean value of 103 nSv.h-1. The dosimetric system described has good potential as a tool for determining baseline background radiation dose rates in an area.
文摘Wireless sensor networks have been identified as one of the key technologies for the 21st century. In order to overcome their limitations such as fault tolerance and conservation of energy, we propose a middleware solution, In-Motes. In-Motes stands as a fault tolerant platform for deploying and monitoring applications in real time offers a number of possibilities for the end user giving him in parallel the freedom to experiment with various parameters, in an effort the deployed applications to run in an energy efficient manner inside the network. The proposed scheme is evaluated through the In-Motes EYE application, aiming to test its merits under real time conditions. In-Motes EYE application which is an agent based real time In-Motes application developed for sensing acceleration variations in an environment. The application was tested in a prototype area, road alike, for a period of four months.
文摘Data evaluation strategies for the novel coupled MCC-IMS sensory system are developed. Mayor attention to the plausibility of applied procedures and the feasibility of automation was paid. Three stages of extraction levels with increasing data reduction are presented for several fields of application. According to suitable extraction levels, real data were tested on various structures of artificial neural networks (ANN) with the result, that the computational levels must still be chosen by expertise, but subsequent processing and training can be fully automated. For the training of larger net- works a method of automated generation of secondary training data is presented which exceeds the quality of previous noise models by far. It is concluded that the combination of MCC-IMS as measuring instrument and ANNs as evalua- tion technique have high potential for industrial use in process monitoring.
文摘Noise measurement using mobile phones is now developed very well. While there are some good applications for the measurement of noise from road traffic, thus on processing of measured data is only paid a very little attention. The data, however, are burdened by specific errors and for further work with them it is necessary to adjust and determine their uncertainty. One of the biggest problems is inaccuracy in position versus the noise source and the shortest length of measurement that can be regarded as representative. Imprecision in terms of location can be determined by calculating the variance of possible distance from the noise source, which for measurement of traffic noise requires a map-matching data points both transverse to the street (sidewalk) network and in the longwise direction. During typical urban measurements, this error can even reach 7 - 10 dB. Three basic types of algorithms for the calculation of uncertainty and positional correction based on the type of input and output data (raster, vector, vector-oriented) were tested. Uncertainty in the variability of the measurement data is necessary to determine from the number of passing vehicles per time unit. The presented solutions are implemented in the Mobile Noise system.