The 5th generation mobile communications aims at connecting everything and future Internet of Things(IoT)will get everything smartly connected.To realize it,there exist many challenges.One key challenge is the battery...The 5th generation mobile communications aims at connecting everything and future Internet of Things(IoT)will get everything smartly connected.To realize it,there exist many challenges.One key challenge is the battery problem for small devices,such as sensors or tags.Batteryless backscatter,also referred to as or battery-free backscatter,is a new potential technology to address this problem.One early and typical type of batteryless backscatter is ambient backscatter.Generally,batteryless backscatter utilizes environmental wireless signals to enable battery-free devices to communicate with each other.These devices first harvest energy from ambient wireless signals and then backscatter these signals so as to transmit their own information.This paper reviews the current studies about batteryless backscatter,including various backscatter schemes and theoretical works,and then introduces open problems for future research.展开更多
Internet of Things (IoT) has attracted extensive interest from both academia and industries, and is recognized as an ultimate infrastructure to connect everything at anytime and anywhere. The implementation of IoT gen...Internet of Things (IoT) has attracted extensive interest from both academia and industries, and is recognized as an ultimate infrastructure to connect everything at anytime and anywhere. The implementation of IoT generally faces the challenges from energy constraint and implementation cost. In this paper, we will introduce a new green communication paradigm, the ambient backscatter (AmBC), that could utilize the environmental wireless signals for both powering a tiny-cost device and backscattering the information symbols. Specifically, we will present the basic principles of AmBC, analyze its features and advantages, suggest its open problems, and predict its potential applications for our future IoT.展开更多
In order to carry out numerical simulation using geologic structural data obtained from Landmark(seismic interpretation system), underground geological structures are abstracted into mechanical models which can reflec...In order to carry out numerical simulation using geologic structural data obtained from Landmark(seismic interpretation system), underground geological structures are abstracted into mechanical models which can reflect actual situations and facilitate their computation and analyses.Given the importance of model building, further processing methods about traditional seismic interpretation results from Landmark should be studied and the processed result can then be directly used in numerical simulation computations.Through this data conversion procedure, Landmark and FLAC(the international general stress software) are seamlessly connected.Thus, the format conversion between the two systems and the pre-and post-processing in simulation computation is realized.A practical application indicates that this method has many advantages such as simple operation, high accuracy of the element subdivision and high speed, which may definitely satisfy the actual needs of floor grid cutting.展开更多
Ambient backscatter is a new green technology for Internet of Things(IoT)that utilizes surrounding wireless signals to enable batteryless devices to communicate with other devices.The battery-free devices first harves...Ambient backscatter is a new green technology for Internet of Things(IoT)that utilizes surrounding wireless signals to enable batteryless devices to communicate with other devices.The battery-free devices first harvest energy from ambient wireless signals and then backscatter the signals for communications.Clearly,sensitivity and distance are two important parameters for system performance.However,most existing studies on ambient backscatter communication systems do not consider the impact of the sensitivity of the energy-harvesting nodes and the distances between these devices.In this paper,we first provide a literature review for ambient communication technology and then take sensitivity and distance as two key parameters and investigate the sensitivity and distance based performance for ambient backscatter communication systems.Specifically,we establish the mathematical model based on distances between transceivers and backscattering nodes,extract a parameter that can differentiate the direct path and the backscattering path,evaluate the effects of transmit beamforming,design an energy detector for the reader,and analyze the outage probability of energy harvesting at the tag and the bit error rate(BER)at the reader.Simulations are then provided to corroborate the proposed studies.展开更多
Various characteristics play very important role in the process of students' second language acquisition and language development,including age,gender,personality,cognitive ability,motivation,learning strategies a...Various characteristics play very important role in the process of students' second language acquisition and language development,including age,gender,personality,cognitive ability,motivation,learning strategies and so on.Among all these factors mentioned,age factor received much attention in second language research.In this essay,two opposing views on age factor are discussed.In the last part,on the basis of the theory,some strategies on the real classroom teaching are provided after the discussion.展开更多
As far as second language acquisition concerned, there are various factors in relation to individual differences that may affect language development. And all the effects of those factors are considerable for teachers...As far as second language acquisition concerned, there are various factors in relation to individual differences that may affect language development. And all the effects of those factors are considerable for teachers to design appropriate and efficient classroom strategies and activities to cater for learners' differences. In this essay, the influence of one of the factors, motivation,is firstly explored before actually designing strategies and activities.展开更多
基金This paper is funded by Scientific Research Program of Beijing Municipal Commission of Education No.KM201910853003.
文摘The 5th generation mobile communications aims at connecting everything and future Internet of Things(IoT)will get everything smartly connected.To realize it,there exist many challenges.One key challenge is the battery problem for small devices,such as sensors or tags.Batteryless backscatter,also referred to as or battery-free backscatter,is a new potential technology to address this problem.One early and typical type of batteryless backscatter is ambient backscatter.Generally,batteryless backscatter utilizes environmental wireless signals to enable battery-free devices to communicate with each other.These devices first harvest energy from ambient wireless signals and then backscatter these signals so as to transmit their own information.This paper reviews the current studies about batteryless backscatter,including various backscatter schemes and theoretical works,and then introduces open problems for future research.
基金supported in part by National Key R&D Program of China under Grant 2016YFE0200900part by Scientific Research Program of Beijing Municipal Commission of Education under Grant KM201910853003part by Major projects of Beijing Municipal Science and Technology Commission under Grant Z181100003218010
文摘Internet of Things (IoT) has attracted extensive interest from both academia and industries, and is recognized as an ultimate infrastructure to connect everything at anytime and anywhere. The implementation of IoT generally faces the challenges from energy constraint and implementation cost. In this paper, we will introduce a new green communication paradigm, the ambient backscatter (AmBC), that could utilize the environmental wireless signals for both powering a tiny-cost device and backscattering the information symbols. Specifically, we will present the basic principles of AmBC, analyze its features and advantages, suggest its open problems, and predict its potential applications for our future IoT.
基金Projects 50221402, 50490271 and 50025413 supported by the National Natural Science Foundation of Chinathe National Basic Research Program of China (2009CB219603, 2009 CB724601, 2006CB202209 and 2005CB221500)+1 种基金the Key Project of the Ministry of Education (306002)the Program for Changjiang Scholars and Innovative Research Teams in Universities of MOE (IRT0408)
文摘In order to carry out numerical simulation using geologic structural data obtained from Landmark(seismic interpretation system), underground geological structures are abstracted into mechanical models which can reflect actual situations and facilitate their computation and analyses.Given the importance of model building, further processing methods about traditional seismic interpretation results from Landmark should be studied and the processed result can then be directly used in numerical simulation computations.Through this data conversion procedure, Landmark and FLAC(the international general stress software) are seamlessly connected.Thus, the format conversion between the two systems and the pre-and post-processing in simulation computation is realized.A practical application indicates that this method has many advantages such as simple operation, high accuracy of the element subdivision and high speed, which may definitely satisfy the actual needs of floor grid cutting.
基金supported by Scientific Research Program of Beijing Municipal Commission of Education(No.KM201910853003)National key research and development program(2020YFB1806604)Fundamental Research Funds for the Central Universities(No.2020YJS044).
文摘Ambient backscatter is a new green technology for Internet of Things(IoT)that utilizes surrounding wireless signals to enable batteryless devices to communicate with other devices.The battery-free devices first harvest energy from ambient wireless signals and then backscatter the signals for communications.Clearly,sensitivity and distance are two important parameters for system performance.However,most existing studies on ambient backscatter communication systems do not consider the impact of the sensitivity of the energy-harvesting nodes and the distances between these devices.In this paper,we first provide a literature review for ambient communication technology and then take sensitivity and distance as two key parameters and investigate the sensitivity and distance based performance for ambient backscatter communication systems.Specifically,we establish the mathematical model based on distances between transceivers and backscattering nodes,extract a parameter that can differentiate the direct path and the backscattering path,evaluate the effects of transmit beamforming,design an energy detector for the reader,and analyze the outage probability of energy harvesting at the tag and the bit error rate(BER)at the reader.Simulations are then provided to corroborate the proposed studies.
文摘Various characteristics play very important role in the process of students' second language acquisition and language development,including age,gender,personality,cognitive ability,motivation,learning strategies and so on.Among all these factors mentioned,age factor received much attention in second language research.In this essay,two opposing views on age factor are discussed.In the last part,on the basis of the theory,some strategies on the real classroom teaching are provided after the discussion.
文摘As far as second language acquisition concerned, there are various factors in relation to individual differences that may affect language development. And all the effects of those factors are considerable for teachers to design appropriate and efficient classroom strategies and activities to cater for learners' differences. In this essay, the influence of one of the factors, motivation,is firstly explored before actually designing strategies and activities.