高校多校区一体化管理中,校区间人员流动频繁,如何保证学校师生在不同校区获得一致的上网体验成为一个难题。除了加快建设多活数据中心,实现重要信息系统的容灾备份体系之外,网络基础设施服务域名系统(Domain Name System,DNS)的一体化...高校多校区一体化管理中,校区间人员流动频繁,如何保证学校师生在不同校区获得一致的上网体验成为一个难题。除了加快建设多活数据中心,实现重要信息系统的容灾备份体系之外,网络基础设施服务域名系统(Domain Name System,DNS)的一体化部署也面临新挑战。以河海大学南京校区和常州校区为例,通过多活容灾网络架构等技术手段部署一体化智能DNS服务,有效解决网络拥塞和信息系统访问瓶颈的问题,同时提升DNS管理的便捷性和服务的安全可靠性,对相关应用场景具有一定参考价值。展开更多
域名系统(domain name system,DNS)作为互联网的核心架构之一,面临可信度不足、安全保护薄弱等问题,而区块链通过多点同步、共享、复制数据提供了一种多中心或去中心,以及难以篡改的数据存储机制,已经成为提高DNS可信度和安全性的重要...域名系统(domain name system,DNS)作为互联网的核心架构之一,面临可信度不足、安全保护薄弱等问题,而区块链通过多点同步、共享、复制数据提供了一种多中心或去中心,以及难以篡改的数据存储机制,已经成为提高DNS可信度和安全性的重要解决方案。然而,当前缺乏对区块链DNS相关文献的全面调研,亟需对相关研究进行综述,以推动区块链在DNS这一互联网的核心架构中的应用,进而提升互联网架构整体安全性。从协议和架构两个角度分析DNS现存的主要安全问题,将DNS威胁划分为重定向流量攻击和拒绝服务攻击;分析了主流防护措施的局限性,梳理了区块链在DNS中的相关研究,概述系统工作流程,从系统复杂度和安全性方面评价了当前方案;提出构建成熟可靠的区块链DNS需要解决的几个关键问题并给出未来研究方向。展开更多
针对DNS可解析性量化评估问题,提出了基于命题逻辑的DNS可解析性量化评估方法。该方法通过对域名解析依赖关系的分析建立域名解析依赖关系图,结合命题逻辑将域名对DNS服务器的依赖性转换为逻辑图,进而将域名的可解析性问题转换为数理逻...针对DNS可解析性量化评估问题,提出了基于命题逻辑的DNS可解析性量化评估方法。该方法通过对域名解析依赖关系的分析建立域名解析依赖关系图,结合命题逻辑将域名对DNS服务器的依赖性转换为逻辑图,进而将域名的可解析性问题转换为数理逻辑中的命题公式的可满足性问题;通过对命题公式进行析取范式的转换和对命题变项数最少的简单合取范式的分析,获取域名可解析的最小DNS服务器组合,从而指导DNS服务器的布置和规划;通过对命题公式进行合取范式的转换和对命题变项数最少的简单析取范式的分析,获取域名不可解析的最小DNS服务器组合,从而对这些DNS服务器进行重点防护。以Alex Top 1000域名为例分析了解析依赖关系,经统计计算发现,Alex Top 1000域名解析平均依赖DNS数量为5.58个;域名解析依赖的最小服务器组合在[1,4]区间内,平均值为1.41个;破坏域名解析的最小服务器组合在[1,6]区间内,平均值为2.44个。展开更多
We systematically studied the evaporation residue cross sections of ^(48)Ca-induced reactions on lanthanide and actinide target nuclei under the Dinuclear System(DNS)model framework to check the reliability and applic...We systematically studied the evaporation residue cross sections of ^(48)Ca-induced reactions on lanthanide and actinide target nuclei under the Dinuclear System(DNS)model framework to check the reliability and applicability of the model.To produce new proton-rich Fl and Lv isotopes through hot fusion reactions in the superheavy element region with Z≥104,we utilized the reactions ^(48)Ca+^(236,238,239) Pu and ^(48)Ca+^(242,243,244,250) Cm.However,owing to the detection limit of available equipment(0.1 pb),only 283Fl and 287−289Lv,which have the maximum evaporation residue cross section values of 0.149,0.130,9.522,and 0.309 pb,respectively,can be produced.Furthermore,to produce neutron-deficient isotopes of actinides near the proton drip line with Z=93−100,we attempted to generate the new isotopes(224−227Pu,228−232,237Cm)using the reactions ^(48)Ca+180,182,183 W and ^(48)Ca+^(184,186,187,192) Os.The maximum evaporation residue cross section values are 0.07,0.06,0.26,and 0.30 nb for the former set of reactions,and 1.96 pb,5.73 pb,12.16 pb,19.39 pb,54.79 pb,and 6.45 nb for the latter,respectively.These results are expected to provide new information for the future synthesis of unknown neutron-deficient isotopes.展开更多
鉴于失败的DNS查询(failed DNS query)能提供恶意网络活动的证据,以DNS查询失败的数据为切入口,提出一种轻量级的基于Counting Bloom Filter的DNS异常检测方法。该方法使用带语义特征的可逆哈希函数对被查询的域名及发起查询的IP进行快...鉴于失败的DNS查询(failed DNS query)能提供恶意网络活动的证据,以DNS查询失败的数据为切入口,提出一种轻量级的基于Counting Bloom Filter的DNS异常检测方法。该方法使用带语义特征的可逆哈希函数对被查询的域名及发起查询的IP进行快速的聚类和还原。实验结果证明该方法能以较少的空间占用和较快的计算速度有效识别出DNS流量中的异常,适用于僵尸网络、分布式拒绝服务(DDoS)攻击等异常检测的前期筛选和后期验证。展开更多
Based on direct numerical simulation (DNS) data of the straight ducts,namely square and rectangular annular ducts,detailed analyses were conducted for the mean streamwise velocity,relevant velocity scales,and turbulen...Based on direct numerical simulation (DNS) data of the straight ducts,namely square and rectangular annular ducts,detailed analyses were conducted for the mean streamwise velocity,relevant velocity scales,and turbulence statistics.It is concluded that turbulent boundary layers (TBL) should be broadly classified into three types (Type-A,-B,and-C) in terms of their distribution patterns of the time-averaged local wall-shear stress (τw) or the mean local frictional velocity (uτ).With reference to the Type-A TBL analysis by von Karman in developing the law-of-the-wall using the time-averaged local frictional velocity (uτ) as scale,the current study extended the approach to the Type-B TBL and obtained the analytical expressions for streamwise velocity in the inner-layer using ensemble-averaged frictional velocity (ūτ) as scale.These analytical formulae were formed by introducing the general damping and enhancing functions.Further,the research applied a near-wall DNS-guided integration to the governing equations of Type-B TBL and quantitatively proved the correctness and accuracy of the inner-layer analytical expressions for this type.展开更多
Understanding and modeling flows over porous layers are of great industrial significance.To accurately solve the turbulent multi-scale flows on complex configurations,a rescaling algorithm designed for turbulent flows...Understanding and modeling flows over porous layers are of great industrial significance.To accurately solve the turbulent multi-scale flows on complex configurations,a rescaling algorithm designed for turbulent flows with the Chapman-Enskog analysis is proposed.The mesh layout and the detailed rescaling procedure are also introduced.Direct numerical simulations(DNSs)for a turbulent channel flow and a porous walled turbulent channel flow are performed with the three-dimensional nineteen-velocity(D3Q19)multiple-relaxation-time(MRT)lattice Boltzmann method(LBM)to validate the accuracy,adaptability,and computational performance of the present rescaling algorithm.The results,which are consistent with the previous DNS studies based on the finite difference method and the LBM,demonstrate that the present method can maintain the continuity of the macro values across the grid interface and is able to adapt to complex geometries.The reasonable time consumption of the rescaling procedure shows that the present method can accurately calculate various turbulent flows with multi-scale and complex configurations while maintaining high computational efficiency.展开更多
文摘高校多校区一体化管理中,校区间人员流动频繁,如何保证学校师生在不同校区获得一致的上网体验成为一个难题。除了加快建设多活数据中心,实现重要信息系统的容灾备份体系之外,网络基础设施服务域名系统(Domain Name System,DNS)的一体化部署也面临新挑战。以河海大学南京校区和常州校区为例,通过多活容灾网络架构等技术手段部署一体化智能DNS服务,有效解决网络拥塞和信息系统访问瓶颈的问题,同时提升DNS管理的便捷性和服务的安全可靠性,对相关应用场景具有一定参考价值。
文摘目的:探讨动态神经肌肉稳定技术(Dynamic Neuromuscular Stabilization,DNS)下的核心稳定训练结合局部针刺运动方案对脑卒中后偏瘫患者步行及姿势控制能力的影响。方法:选取2022年3月~2022年9月在郴州市第一人民医院就诊的脑卒中患者90例,按随机数字表分为对照组(n=45)和观察组(n=45),对照组采用常规康复训练,观察组在此基础上增加DNS核心稳定训练结合局部针刺运动疗法。治疗8周后,对比并分析治疗前后两组患者步态时空参数中步长、步速、步频参数;步态时相参数中双支撑相占步态周期百分比、患侧单支撑相占步态周期百分比、步行周期参数;脑卒中患者姿势控制量表(Posture assessment of stoke scale,PASS)量表、Tinnetti(Performance-Oriented Assessment of Mobility)量表及Fugl-Meyer下肢运动功能(FMA-LE)量表评分数据。结果:治疗后,两组步长、步速、步频参数、双支撑相占步态周期百分比、患侧单支撑相占步态周期百分比、Tinnetti评分、PASS评分及FMA评分均显著高于治疗前(P<0.05),步行周期显著低于治疗前(P<0.05),且观察组治疗后步长、步速、步频参数、双支撑相占步态周期百分比、患侧单支撑相占步态周期百分比、PASS评分、Tinnetti评分及FMALE评分均显著高于对照组(P<0.05),步行周期则低于对照组(P<0.05)。结论:DNS核心稳定训练结合局部针刺运动可提高脑卒中后偏瘫患者核心稳定及姿势控制能力,改善步行功能。
文摘域名系统(domain name system,DNS)作为互联网的核心架构之一,面临可信度不足、安全保护薄弱等问题,而区块链通过多点同步、共享、复制数据提供了一种多中心或去中心,以及难以篡改的数据存储机制,已经成为提高DNS可信度和安全性的重要解决方案。然而,当前缺乏对区块链DNS相关文献的全面调研,亟需对相关研究进行综述,以推动区块链在DNS这一互联网的核心架构中的应用,进而提升互联网架构整体安全性。从协议和架构两个角度分析DNS现存的主要安全问题,将DNS威胁划分为重定向流量攻击和拒绝服务攻击;分析了主流防护措施的局限性,梳理了区块链在DNS中的相关研究,概述系统工作流程,从系统复杂度和安全性方面评价了当前方案;提出构建成熟可靠的区块链DNS需要解决的几个关键问题并给出未来研究方向。
文摘针对DNS可解析性量化评估问题,提出了基于命题逻辑的DNS可解析性量化评估方法。该方法通过对域名解析依赖关系的分析建立域名解析依赖关系图,结合命题逻辑将域名对DNS服务器的依赖性转换为逻辑图,进而将域名的可解析性问题转换为数理逻辑中的命题公式的可满足性问题;通过对命题公式进行析取范式的转换和对命题变项数最少的简单合取范式的分析,获取域名可解析的最小DNS服务器组合,从而指导DNS服务器的布置和规划;通过对命题公式进行合取范式的转换和对命题变项数最少的简单析取范式的分析,获取域名不可解析的最小DNS服务器组合,从而对这些DNS服务器进行重点防护。以Alex Top 1000域名为例分析了解析依赖关系,经统计计算发现,Alex Top 1000域名解析平均依赖DNS数量为5.58个;域名解析依赖的最小服务器组合在[1,4]区间内,平均值为1.41个;破坏域名解析的最小服务器组合在[1,6]区间内,平均值为2.44个。
基金National Natural Science Foundation of China(Nos.12175064 and U2167203)Hunan Outstanding Youth Science Foundation(No.2022JJ10031).
文摘We systematically studied the evaporation residue cross sections of ^(48)Ca-induced reactions on lanthanide and actinide target nuclei under the Dinuclear System(DNS)model framework to check the reliability and applicability of the model.To produce new proton-rich Fl and Lv isotopes through hot fusion reactions in the superheavy element region with Z≥104,we utilized the reactions ^(48)Ca+^(236,238,239) Pu and ^(48)Ca+^(242,243,244,250) Cm.However,owing to the detection limit of available equipment(0.1 pb),only 283Fl and 287−289Lv,which have the maximum evaporation residue cross section values of 0.149,0.130,9.522,and 0.309 pb,respectively,can be produced.Furthermore,to produce neutron-deficient isotopes of actinides near the proton drip line with Z=93−100,we attempted to generate the new isotopes(224−227Pu,228−232,237Cm)using the reactions ^(48)Ca+180,182,183 W and ^(48)Ca+^(184,186,187,192) Os.The maximum evaporation residue cross section values are 0.07,0.06,0.26,and 0.30 nb for the former set of reactions,and 1.96 pb,5.73 pb,12.16 pb,19.39 pb,54.79 pb,and 6.45 nb for the latter,respectively.These results are expected to provide new information for the future synthesis of unknown neutron-deficient isotopes.
文摘鉴于失败的DNS查询(failed DNS query)能提供恶意网络活动的证据,以DNS查询失败的数据为切入口,提出一种轻量级的基于Counting Bloom Filter的DNS异常检测方法。该方法使用带语义特征的可逆哈希函数对被查询的域名及发起查询的IP进行快速的聚类和还原。实验结果证明该方法能以较少的空间占用和较快的计算速度有效识别出DNS流量中的异常,适用于僵尸网络、分布式拒绝服务(DDoS)攻击等异常检测的前期筛选和后期验证。
基金the National Natural Science Foundation of China(91434112)the United Innovation Program of Shanghai Commercial Aircraft Engine(AR908)the Shanghai Thousand Talents Program(EZH2126503).
文摘Based on direct numerical simulation (DNS) data of the straight ducts,namely square and rectangular annular ducts,detailed analyses were conducted for the mean streamwise velocity,relevant velocity scales,and turbulence statistics.It is concluded that turbulent boundary layers (TBL) should be broadly classified into three types (Type-A,-B,and-C) in terms of their distribution patterns of the time-averaged local wall-shear stress (τw) or the mean local frictional velocity (uτ).With reference to the Type-A TBL analysis by von Karman in developing the law-of-the-wall using the time-averaged local frictional velocity (uτ) as scale,the current study extended the approach to the Type-B TBL and obtained the analytical expressions for streamwise velocity in the inner-layer using ensemble-averaged frictional velocity (ūτ) as scale.These analytical formulae were formed by introducing the general damping and enhancing functions.Further,the research applied a near-wall DNS-guided integration to the governing equations of Type-B TBL and quantitatively proved the correctness and accuracy of the inner-layer analytical expressions for this type.
基金Project supported by the National Natural Science Foundation of China(Nos.12172207 and 92052201)。
文摘Understanding and modeling flows over porous layers are of great industrial significance.To accurately solve the turbulent multi-scale flows on complex configurations,a rescaling algorithm designed for turbulent flows with the Chapman-Enskog analysis is proposed.The mesh layout and the detailed rescaling procedure are also introduced.Direct numerical simulations(DNSs)for a turbulent channel flow and a porous walled turbulent channel flow are performed with the three-dimensional nineteen-velocity(D3Q19)multiple-relaxation-time(MRT)lattice Boltzmann method(LBM)to validate the accuracy,adaptability,and computational performance of the present rescaling algorithm.The results,which are consistent with the previous DNS studies based on the finite difference method and the LBM,demonstrate that the present method can maintain the continuity of the macro values across the grid interface and is able to adapt to complex geometries.The reasonable time consumption of the rescaling procedure shows that the present method can accurately calculate various turbulent flows with multi-scale and complex configurations while maintaining high computational efficiency.
