针对物联网系统中海量的异构数据流影响数据处理效率的问题,提出一种结合RESTful Web Service和Mongo DB数据库的物联网系统异构数据过滤及存储模型。提出数据点的概念对设备节点的物理量进行抽象描述,通过对数据点存储状态的设置实现...针对物联网系统中海量的异构数据流影响数据处理效率的问题,提出一种结合RESTful Web Service和Mongo DB数据库的物联网系统异构数据过滤及存储模型。提出数据点的概念对设备节点的物理量进行抽象描述,通过对数据点存储状态的设置实现数据的过滤,同时采用内嵌文档形式对数据进行存储。该模型经过测试,可实现物联网系统中异构数据的选择性存储,并可有效提高数据库的存储效率及存储利用率。展开更多
Manganese cobaltite(MnCo_(2)_(4))is a promising electrode material because of its attractive redox chemistry and excellent charge storage capability.Our previous work demonstrated that the octahedrally-coordinated Mn ...Manganese cobaltite(MnCo_(2)_(4))is a promising electrode material because of its attractive redox chemistry and excellent charge storage capability.Our previous work demonstrated that the octahedrally-coordinated Mn are prone to react with the hydroxyl ions in alkaline electrolyte upon electrochemical cycling and separates on the surface of spinel to reconstruct into d-MnO_(2) nanosheets irreversibly,thus results in a change of the reaction mechanism with Kþion intercalation.However,the low capacity has greatly limited its practical application.Herein,we found that the tetrahedrally-coordinated Co_(2) þions were leached when MnCo_(2)_(4) was equilibrated in 1 mol L^(-1) HCl solution,leading to the formation of layered CoOOH on MnCo_(2)_(4) surface which is originated from the covalency competition induced selective breakage of the CoT–O bond in CoT–O–CoO and subsequent rearrangement of free Co_(6) octahedra.The as-formed CoOOH is stable upon cycling in alkaline electrolyte,exhibits conversion reaction mechanism with facile proton diffusion and is free of massive structural evolution,thus enables utilization of the bulk electrode material and realizes enhanced specific capacity as well as facilitated charge transfer and ion diffusion.In general,our work not only offers a feasible approach to deliberate modification of MnCo_(2)_(4)'s surface structure,but also provides an in-depth understanding of its charge storage mechanism,which enables rational design of the spinel oxides with promising charge storage properties.展开更多
Evidence-based selective cutting at prescribed intervals as part of good forest management can enhance the carbon sequestration capacity of the forest.The effect of forest management on carbon sequestration has,howeve...Evidence-based selective cutting at prescribed intervals as part of good forest management can enhance the carbon sequestration capacity of the forest.The effect of forest management on carbon sequestration has,however,not been quantified.Thus,carbon content of various organs was measured for 323 tree species,247 shrub species,and233 herb species in seven temperate coniferous and broadleaved mixed forests that were subjected to selective cutting with restoration durations of 100,55,45,36,25,14,and6 years to explore dynamic changes in carbon storage.The results showed that biomass carbon allocation in different organs followed a pattern:trunk>root>branch>leaf for all forests.With longer restoration durations,more carbon accumulated in different organs and in soils.Interestingly,when the restoration duration exceeded 50 years,carbon storage in ecosystem was larger than that in primary forests with 100-year cutting intervals,suggesting that a reasonable selective cutting interval can increase forest carbon sequestration.Mean diameter at breast height(DBH)and forest carbon storage were significantly positively correlated,and carbon storage of selectively cut forests exceeded that of primary forests when the stand mean DBH exceeded 15.66 cm.Therefore,mean DBH of forests can be an indicator for combining sustainable forest management and forest carbon sequestration.Additionally,the classic coefficients of 0.45 and 0.50 used to estimate carbon sequestration underestimated values by 2.65%and overestimated by 8.16%,respectively,in comparison with the measured carbon content from different plant organs.展开更多
物联网系统中大量的用户终端及设备终端之间的信息交互会产生海量的异构数据流,数据中心需要及时分析和处理这些数据,选择对用户有用的数据进行存储,可以便于对设备的当前与历史状态进行查询,同时为设备的大数据服务提供数据基础.针对...物联网系统中大量的用户终端及设备终端之间的信息交互会产生海量的异构数据流,数据中心需要及时分析和处理这些数据,选择对用户有用的数据进行存储,可以便于对设备的当前与历史状态进行查询,同时为设备的大数据服务提供数据基础.针对此问题,同时结合物联网系统异构型数据存储的特点和通信实时性、可靠性需求以及对不同终端的通用性,提出一种结合Mongo DB数据库、RESTful Web Service、MQTT通信、JMS消息服务等技术的物联网系统历史数据的管理及存储系统架构,实现各设备节点历史数据的获取、选择性存储、删除及查询等功能,并可适用于不同设备终端.该系统架构经过长期测试,可实现物联网系统中各设备节点数据的获取和集中管理,并可有效提高数据库的存储效率及存储利用率.展开更多
数据持有性证明(provable data possession,简称PDP)和数据可恢复性证明(proofs of retrievability,简称POR)是客户端用来验证存储在云端服务器上数据完整性的主要技术.近几年,它在学术界和工业界的应用广泛,很多PDP和POR方案相继出现....数据持有性证明(provable data possession,简称PDP)和数据可恢复性证明(proofs of retrievability,简称POR)是客户端用来验证存储在云端服务器上数据完整性的主要技术.近几年,它在学术界和工业界的应用广泛,很多PDP和POR方案相继出现.但是由于不同群组的特殊性和独特要求,使得群组PDP/POR方案多样化,并且群组应用中的许多重要功能(例如数据去重)没有被实现.如何构造高效及满足群组特定功能和安全需求的PDP/POR方案,已经引起了人们的广泛关注.给出了一种支持数据去重的群组PDP方案(GPDP),基于矩阵计算和伪随机函数,GPDP可以在支持数据去重的基础上,高效地完成数据持有性证明,并且可以在群组中抵抗恶意方选择成员攻击.在标准模型下证明了GPDP的安全性,并且在百度云平台上实现了GPDP的原型系统.为了评估方案的性能,使用了10GB的数据量进行实验和分析,结果表明:GPDP方案在达到群组中数据去重的目标的基础上,可以高效地保证抵抗选择攻击和数据持有性,即:预处理效率高于私有验证方案,而验证效率高于公开验证方案(与私有验证效率几乎相同).另外,与其他群组PDP/POR方案相比,GPDP方案将额外存储代价和通信代价都降到了最低.展开更多
文摘针对物联网系统中海量的异构数据流影响数据处理效率的问题,提出一种结合RESTful Web Service和Mongo DB数据库的物联网系统异构数据过滤及存储模型。提出数据点的概念对设备节点的物理量进行抽象描述,通过对数据点存储状态的设置实现数据的过滤,同时采用内嵌文档形式对数据进行存储。该模型经过测试,可实现物联网系统中异构数据的选择性存储,并可有效提高数据库的存储效率及存储利用率。
基金supported by the National Key Research and Development Program of China(2022YFE0206300)the National Natural Science Foundation of China(22209047,U21A2081,22075074)+2 种基金Natural Science Foundation of Hunan Province(2020JJ5035)Hunan Provincial Department of Education Outstanding Youth Project(23B0037)Macao Science and Technology Development Fund(Macao SAR,FDCT-0096/2020/A2).
文摘Manganese cobaltite(MnCo_(2)_(4))is a promising electrode material because of its attractive redox chemistry and excellent charge storage capability.Our previous work demonstrated that the octahedrally-coordinated Mn are prone to react with the hydroxyl ions in alkaline electrolyte upon electrochemical cycling and separates on the surface of spinel to reconstruct into d-MnO_(2) nanosheets irreversibly,thus results in a change of the reaction mechanism with Kþion intercalation.However,the low capacity has greatly limited its practical application.Herein,we found that the tetrahedrally-coordinated Co_(2) þions were leached when MnCo_(2)_(4) was equilibrated in 1 mol L^(-1) HCl solution,leading to the formation of layered CoOOH on MnCo_(2)_(4) surface which is originated from the covalency competition induced selective breakage of the CoT–O bond in CoT–O–CoO and subsequent rearrangement of free Co_(6) octahedra.The as-formed CoOOH is stable upon cycling in alkaline electrolyte,exhibits conversion reaction mechanism with facile proton diffusion and is free of massive structural evolution,thus enables utilization of the bulk electrode material and realizes enhanced specific capacity as well as facilitated charge transfer and ion diffusion.In general,our work not only offers a feasible approach to deliberate modification of MnCo_(2)_(4)'s surface structure,but also provides an in-depth understanding of its charge storage mechanism,which enables rational design of the spinel oxides with promising charge storage properties.
基金supported financially by the Natural Science Foundation of China(31,800,368,31,872,683)the National Key R&D program of China(2017YFC0504004)by the program of Youth Innovation Research Team Project(LENOM2016Q0005)。
文摘Evidence-based selective cutting at prescribed intervals as part of good forest management can enhance the carbon sequestration capacity of the forest.The effect of forest management on carbon sequestration has,however,not been quantified.Thus,carbon content of various organs was measured for 323 tree species,247 shrub species,and233 herb species in seven temperate coniferous and broadleaved mixed forests that were subjected to selective cutting with restoration durations of 100,55,45,36,25,14,and6 years to explore dynamic changes in carbon storage.The results showed that biomass carbon allocation in different organs followed a pattern:trunk>root>branch>leaf for all forests.With longer restoration durations,more carbon accumulated in different organs and in soils.Interestingly,when the restoration duration exceeded 50 years,carbon storage in ecosystem was larger than that in primary forests with 100-year cutting intervals,suggesting that a reasonable selective cutting interval can increase forest carbon sequestration.Mean diameter at breast height(DBH)and forest carbon storage were significantly positively correlated,and carbon storage of selectively cut forests exceeded that of primary forests when the stand mean DBH exceeded 15.66 cm.Therefore,mean DBH of forests can be an indicator for combining sustainable forest management and forest carbon sequestration.Additionally,the classic coefficients of 0.45 and 0.50 used to estimate carbon sequestration underestimated values by 2.65%and overestimated by 8.16%,respectively,in comparison with the measured carbon content from different plant organs.
文摘物联网系统中大量的用户终端及设备终端之间的信息交互会产生海量的异构数据流,数据中心需要及时分析和处理这些数据,选择对用户有用的数据进行存储,可以便于对设备的当前与历史状态进行查询,同时为设备的大数据服务提供数据基础.针对此问题,同时结合物联网系统异构型数据存储的特点和通信实时性、可靠性需求以及对不同终端的通用性,提出一种结合Mongo DB数据库、RESTful Web Service、MQTT通信、JMS消息服务等技术的物联网系统历史数据的管理及存储系统架构,实现各设备节点历史数据的获取、选择性存储、删除及查询等功能,并可适用于不同设备终端.该系统架构经过长期测试,可实现物联网系统中各设备节点数据的获取和集中管理,并可有效提高数据库的存储效率及存储利用率.
文摘数据持有性证明(provable data possession,简称PDP)和数据可恢复性证明(proofs of retrievability,简称POR)是客户端用来验证存储在云端服务器上数据完整性的主要技术.近几年,它在学术界和工业界的应用广泛,很多PDP和POR方案相继出现.但是由于不同群组的特殊性和独特要求,使得群组PDP/POR方案多样化,并且群组应用中的许多重要功能(例如数据去重)没有被实现.如何构造高效及满足群组特定功能和安全需求的PDP/POR方案,已经引起了人们的广泛关注.给出了一种支持数据去重的群组PDP方案(GPDP),基于矩阵计算和伪随机函数,GPDP可以在支持数据去重的基础上,高效地完成数据持有性证明,并且可以在群组中抵抗恶意方选择成员攻击.在标准模型下证明了GPDP的安全性,并且在百度云平台上实现了GPDP的原型系统.为了评估方案的性能,使用了10GB的数据量进行实验和分析,结果表明:GPDP方案在达到群组中数据去重的目标的基础上,可以高效地保证抵抗选择攻击和数据持有性,即:预处理效率高于私有验证方案,而验证效率高于公开验证方案(与私有验证效率几乎相同).另外,与其他群组PDP/POR方案相比,GPDP方案将额外存储代价和通信代价都降到了最低.
