检索结果-南通市图书馆

Equilibrium and kinetic Si isotope fractionation factors and their implications for Si isotope distributions in the Earth's surface environments

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2016年第1期35卷 15-24页

作者： Hong-tao He Siting Zhang Chen Zhu yun liu State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China University of Chinese Academy of Sciences Beijing 100049China Department of Geological Sciences Indiana UniversityBloomingtonIN 47405USA

Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth's surface *** results reveal that,in comparison to aqueous H_4SiO_4,heavy Si isotopes will be significantly enriched in secondary silicate *** the contrary,quadra-coordinated organosilicon complexes are enriched in light silicon isotope relative to the *** extent of ^(28)Si-enrichment in hyper-coordinated organosilicon complexes was found to be the *** addition,the large kinetic isotope effect associated with the polymerization of monosilicic acid and dimer was calculated,and the results support the previous statement that highly ^(28)Sienrichment in the formation of amorphous quartz precursor contributes to the discrepancy between theoretical calculations and field *** the equilibrium Si isotope fractionation factors provided here,Si isotope distributions in many of Earth's surface systems can be *** example,the change of bulk soil δ^(30)Si can be predicted as a concave pattern with respect to the weathering degree,with the minimum value where allophane completely dissolves and the total amount of sesquioxides and poorly crystalline minerals reaches their ***,under equilibrium conditions,the well-crystallized clays start to precipitate from the pore solutions,the bulk soil δ^(30)Si will increase again and reach a constant ***,the precipitation of crystalline smectite and the dissolution of poorly crystalline kaolinite may explain the δ^(30)Si variations in the ground water *** equilibrium Si isotope fractionations among the quadracoordinated organosilicon complexes and the H_4SiO_4solution may also shed light on the Si isotope distributions in the Si-accumulating plants.

关键词： Si isotopes Equilibrium fractionation factor Quantum chemistry calculation Cluster model Kinetic isotope effect

在线全文

学校读者我要写书评

暂无评论

深度教学中直抵地理思想方法的课堂追问探究

教学与管理 2025年第1期 72-76页

作者：刘导黄东涛深圳市宝安区教育科学研究院广东深圳518000 汕头市金山中学广东汕头515100

深度教学中直抵地理思想方法的课堂追问是学生告别浅表的知识符号学习,不断深入发现、解释、提炼和总结地理规律与原理的过程。审视地理深度教学中的追问现状,地理思想方法在课堂追问中的运用存在着无结构、无梯度、无深度的实然状态。... 详细信息

深度教学中直抵地理思想方法的课堂追问是学生告别浅表的知识符号学习,不断深入发现、解释、提炼和总结地理规律与原理的过程。审视地理深度教学中的追问现状,地理思想方法在课堂追问中的运用存在着无结构、无梯度、无深度的实然状态。直抵地理思想方法的深度教学追问应具有溯源性、系统性、渐进性、开放性、辩证性、迁移性等样态特征。在地理思想方法的关照下,深度追问具有自身的发生时机和发生步骤,并以地理思想方法中的学科内涵、地理专家研究成果或是地理空间结构表达为抓手,落实形成地理深度教学中课堂追问的过程和方法。

关键词：深度教学地理思想方法课堂追问

Jointly optimized congestion control, forwarding strategy,and link scheduling in a named-data multihop wireless network

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2017年第10期18卷 1573-1590页

作者： Cheng-cheng LI Ren-chao XIE tao HUANG yun-jie liu State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing Advanced Innovation Center for Future Internet Technology Beijing University of Technology

As a promising future network architecture, named data networking(NDN) has been widely considered as a very appropriate network protocol for the multihop wireless network(MWN). In named-data MWNs, congestion control is a critical issue. Independent optimization for congestion control may cause severe performance degradation if it can not cooperate well with protocols in other layers. Cross-layer congestion control is a potential method to enhance performance. There have been many cross-layer congestion control mechanisms for MWN with Internet Protocol(IP). However, these cross-layer mechanisms for MWNs with IP are not applicable to named-data MWNs because the communication characteristics of NDN are different from those of IP. In this paper, we study the joint congestion control, forwarding strategy, and link scheduling problem for named-data MWNs. The problem is modeled as a network utility maximization(NUM) problem. Based on the approximate subgradient algorithm, we propose an algorithm called ‘jointly optimized congestion control, forwarding strategy, and link scheduling(JOCFS)'to solve the NUM problem distributively and iteratively. To the best of our knowledge, our proposal is the first cross-layer congestion control mechanism for named-data MWNs. By comparison with the existing congestion control mechanism, JOCFS can achieve a better performance in terms of network throughput, fairness, and the pending interest table(PIT) size.

关键词： Information-centric networking Congestion control Cross-layer design Multihop wireless network

An artificial intelligence diabetes management architecture based on 5G

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第1期10卷 75-82页

作者： Ruochen Huang Wei Feng Shan Lu tao shan Changwei Zhang yun liu Department of Geriatrics The First Affiliated Hospital of Nanjing Medical UniversityNanjing210096China Department of Information The First Afliated Hospital of Nanjing Medical UniversityNanjing210096China Department of Medical Informatics School of Biomedical Engineering and InformaticsNanjing Medical UniversityNanjing211166China Department of Outpatient The First Affiliated Hospital of Nanjing Medical UniversityNanjing210096China Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing210003China

Along with the development of 5G network and Internet of Things technologies,there has been an explosion in personalized healthcare *** the 5G and Artificial Intelligence(Al)is introduced into diabetes management architecture,it can increase the efficiency of existing systems and complications of diabetes can be handled more effectively by taking advantage of *** this article,we propose a 5G-based Artificial Intelligence Diabetes Management architecture(AIDM),which can help physicians and patients to manage both acute complications and chronic *** AIDM contains five layers:the sensing layer,the transmission layer,the storage layer,the computing layer,and the application *** build a test bed for the transmission and application ***,we apply a delay-aware RA optimization based on a double-queue model to improve access efficiency in smart hospital wards in the transmission *** application layer,we build a prediction model using a deep forest *** on real-world data show that our AIDM can enhance the efficiency of diabetes management and improve the screening rate of diabetes as well.

关键词： Diabetes 5G Artificial intelligence Deep forest Smart hospital ward

调控生鲜猪肉过冷保鲜的逐步降温循环程序构建

在线全文

学校读者我要写书评

暂无评论

核农学报 2025年第2期39卷 307-316页

作者：陶雨刘浩泉叶可萍南京农业大学食品科技学院/肉品质量控制与新资源创制全国重点实验室/国家肉品质量安全控制工程技术研究中心/江苏省肉类生产与加工质量安全控制协同创新中心江苏南京210095 青岛海尔电冰箱有限公司山东青岛266100

为实现生鲜猪肉在冰点以下稳定过冷贮藏,本研究分析了逐步降温过程中初始温度和降温时间间隔对生鲜猪肉过冷的影响,构建调控生鲜猪肉过冷的最佳逐步降温循环程序,并评估生鲜猪肉在此条件下贮藏12 d的保鲜效果。结果表明,降温时间间隔显... 详细信息

为实现生鲜猪肉在冰点以下稳定过冷贮藏,本研究分析了逐步降温过程中初始温度和降温时间间隔对生鲜猪肉过冷的影响,构建调控生鲜猪肉过冷的最佳逐步降温循环程序,并评估生鲜猪肉在此条件下贮藏12 d的保鲜效果。结果表明,降温时间间隔显著影响生鲜猪肉的过冷点和过冷度。相较于12和18 h降温时间间隔组,6 h降温时间间隔组样品的过冷点显著降低、过冷度显著升高。在此基础上确定初始温度-1.5℃、降温时间间隔6 h、最低温度-3.5℃的逐步降温循环为调控生鲜猪肉过冷的最佳程序,此程序下贮藏12 d时生鲜猪肉过冷率达100%。与-3.5℃组冻结样品相比,各逐步降温循环程序显著降低了贮藏12 d样品的汁液流失率,延缓了猪肉中结合水和不易流动水向自由水的转化,提高了猪肉的持水力。相比-1至-3.5℃组,更低温度的-1.5至-3.5℃、-2至-3.5℃逐步降温循环程序可有效抑制贮藏期间生鲜猪肉中微生物的生长,延缓蛋白质腐败降解、更好地保持样品的新鲜度,且上述两组样品的挥发性盐基氮(TVB-N)和硫代巴比妥酸反应物(TBARS)含量与-3.5℃组样品无显著差异。该研究可为高品质生鲜肉的新型贮藏保鲜技术开发和设备开发提供科学依据,进而促进我国生鲜肉冷链物流的发展。

关键词：逐步降温循环程序过冷猪肉贮藏保鲜

维普期刊数据库博看期刊

Reverse-trace routing scheme in content centric networking

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2013年第5期20卷 22-29页

作者： ZHANG Yan HUANG tao liu Jiang CHEN Jian-ya liu yun-jie Key Laboratory of Universal Wireless Communications of Ministry of Education Beijing University of Posts and Telecommunications

Content center networking （CCN） is one of the most promising future network architectures. Current researches on CCN routing scheme mainly focus on finding the best single routing path, which may induce to low usage of the in-network caches. In order to overcome this problem, a reverse trace routing （RTR） scheme is proposed in this paper, in which Interest packet is sent to the edge-cache along with the reverse trace of the corresponding former Data packet. By doing this, the Interest packets will have better chances to be routed to the promising in-network caches before reaching the source server, which could increase the in-network hit rate, while decrease the server stress. The simulation results show clearly that the RTR scheme decreases the source server load, while reducing the mean hops of entire data retrieval process under certain circumstances.

关键词： CCN routing RTR next face table (NFT)

New algorithm for hub-and-spoke topological virtual networks embedding problem

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2012年第1期19卷 55-61页

作者： liu Jiang HUANG tao CHEN Jian-ya liu yun-jie LÜ Bo Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and TelecommunicationsBeijing 100876China

The virtual network embedding/mapping problem is a core issue of the network virtualization. It＇s mainly concerned with how to map virtual network requests to the substrate network efficiently. Previous researches mainly focus on developing heuristic algorithms for general topology virtual network request. In this paper, we propose a new algorithm for the hub-and-spoke （HAS） topology virtual request. The characters of the HAS topology are exploited to develop the new algorithm. The simulation results show that the new algorithm greatly enhances the performance of revenue/cost （R/C） ratio while the HAS topology request arrives.

关键词： virtual network embedding general topology HAS topology

Fast convergence caching replacement algorithm based on dynamic classification for content-centric networks

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2013年第5期20卷 45-50页

作者： FANG Chao HUANG tao liu Jiang CHEN Jian-ya liu yun-jie Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and Telecommunications

One of the key research fields of content-centric networking （CCN） is to develop more efficient cache replacement policies to improve the hit ratio of CCN in-network caching. However, most of existing cache strategies designed mainly based on the time or frequency of content access, can not properly deal with the problem of the dynamicity of content popularity in the network. In this paper, we propose a fast convergence caching replacement algorithm based on dynamic classification method for CCN, named as FCDC. It develops a dynamic classification method to reduce the time complexity of cache inquiry, which achieves a higher caching hit rate in comparison to random classification method under dynamic change of content popularity. Meanwhile, in order to relieve the influence brought about by dynamic content popularity, it designs a weighting function to speed up cache hit rate convergence in the CCN router. Experimental results show that the proposed scheme outperforms the replacement policies related to least recently used （LRU） and recent usage frequency （RUF） in cache hit rate and resiliency when content popularity in the network varies.

关键词： CCN cache replacement policy dynamic classification fast convergence category popularity

甲基硫菌灵及其代谢产物多菌灵在柑橘中的残留及消解动态

在线全文

学校读者我要写书评

暂无评论

农药 2018年第4期57卷 276-278,293页

作者：肖璐璐王昱翔王娅张星吕运涛刘照清刘春来刘一平李晓刚湖南农业大学植物保护学院长沙410128 湖南省农药检定所长沙410000

[目的]通过建立一种测定柑橘中甲基硫菌灵及其代谢产物多菌灵残留量的分析方法,对其在柑橘和土壤中的残留消解动态以及最终残留量进行研究。[方法]样品前处理采用优化的Qu ECh ERS方法,利用超高效液相色谱-串联质谱(UPLC-MS/MS)进行检测... 详细信息

[目的]通过建立一种测定柑橘中甲基硫菌灵及其代谢产物多菌灵残留量的分析方法,对其在柑橘和土壤中的残留消解动态以及最终残留量进行研究。[方法]样品前处理采用优化的Qu ECh ERS方法,利用超高效液相色谱-串联质谱(UPLC-MS/MS)进行检测,外标法定量。[结果]在0.004~4.0 mg/L的质量浓度范围内,甲基硫菌灵和多菌灵的质量浓度与响应值呈良好的线性关系;在0.004~4.0 mg/L添加质量浓度范围内,甲基硫菌灵和多菌灵的平均回收率为87.8%~117.9%,相对标准偏差(RSDs)为1.3%~10.7%;甲基硫菌灵和多菌灵的检出限(LOD)分别为0.05、0.005 ng,其定量限(LOQ)分别为0.01、0.004 mg/kg。[结论]该方法具有灵敏度高、操作简便,快速高效等优点,且符合农药残留检测的要求。甲基硫菌灵在柑橘全果的消解动态结果显示,其半衰期为2.8~6.4d,属于易降解农药;7d后在柑橘中的最终残留量为0.127~2.277mg/kg,低于我国规定的最大残留限量值5.0mg/kg,表明甲基硫菌灵对柑橘安全。

关键词：超高效液相色谱-串联质谱柑橘农药残留甲基硫菌灵多菌灵