当前美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)对后量子密码(Post-Quantum Cryptography,PQC)标准化方案的评估已进入第四轮,位翻转密钥封装(Bit Flipping Key Encapsulation,BIKE)协议是目前被...当前美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)对后量子密码(Post-Quantum Cryptography,PQC)标准化方案的评估已进入第四轮,位翻转密钥封装(Bit Flipping Key Encapsulation,BIKE)协议是目前被评估的四个候选方案之一.在BIKE的密钥生成算法中,多项式乘法作为众多密码系统中特别耗时的操作之一,耗费了大量的时间和面积资源.针对此问题,本文设计了一种基于Karatsuba算法(Karatsuba Algorithm,KA)的无交叠多项式乘法器,可高效实现万级比特位宽的多项式乘法,具有低时延、高性能和面积小的特点.同时,本文将该优化乘法器应用于BIKE密钥生成算法中,并基于现场可编程门阵列(Field Programmable Gate Array,FPGA)对其进行硬件架构实现,改进了原有的紧凑多项式乘法和多项式求逆算法.本文提出的乘法器通过采用不同的操作数位宽,可适应对面积和延时的不同需求.与BIKE原本的设计相比,改进的设计使密钥生成模块的延时减小了36.54%,面积延迟积(Area Delay Production,ADP)减小了10.4%.展开更多
This study concerns a Ka-band solid-state transmitter cloud radar, made in China, which can operate in three different work modes, with different pulse widths, and coherent and incoherent integration numbers, to meet ...This study concerns a Ka-band solid-state transmitter cloud radar, made in China, which can operate in three different work modes, with different pulse widths, and coherent and incoherent integration numbers, to meet the requirements for cloud remote sensing over the Tibetan Plateau. Specifically, the design of the three operational modes of the radar（i.e., boundary mode M1, cirrus mode M2, and precipitation mode M3） is introduced. Also, a cloud radar data merging algorithm for the three modes is proposed. Using one month＇s continuous measurements during summertime at Naqu on the Tibetan Plateau,we analyzed the consistency between the cloud radar measurements of the three modes. The number of occurrences of radar detections of hydrometeors and the percentage contributions of the different modes＇ data to the merged data were estimated.The performance of the merging algorithm was evaluated. The results indicated that the minimum detectable reflectivity for each mode was consistent with theoretical results. Merged data provided measurements with a minimum reflectivity of -35 dBZ at the height of 5 km, and obtained information above the height of 0.2 km. Measurements of radial velocity by the three operational modes agreed very well, and systematic errors in measurements of reflectivity were less than 2 dB. However,large discrepancies existed in the measurements of the linear depolarization ratio taken from the different operational modes.The percentage of radar detections of hydrometeors in mid- and high-level clouds increased by 60% through application of pulse compression techniques. In conclusion, the merged data are appropriate for cloud and precipitation studies over the Tibetan Plateau.展开更多
随着量子计算的发展,现有密码系统的安全性将受到严重威胁.Saber算法是抵御量子计算攻击的后量子密码方案之一,但存在多项式商环上模乘占据运算开销过大的问题.鉴此,本文通过对Karatsuba算法和Schoolbook相乘方式的剖析,提出一种面向Sa...随着量子计算的发展,现有密码系统的安全性将受到严重威胁.Saber算法是抵御量子计算攻击的后量子密码方案之一,但存在多项式商环上模乘占据运算开销过大的问题.鉴此,本文通过对Karatsuba算法和Schoolbook相乘方式的剖析,提出一种面向Saber算法的并行乘法器设计方案.该方案首先利用Karatsuba算法分解模乘运算的关键路径,结合乘法复用和加法替换的策略减少硬件开销,然后采用并行运算电路压缩关键运算路径时长,最后在TSMC 65 nm工艺下,利用Modelsim和DC软件仿真验证.结果表明:该方案运算时长为137个时钟周期,与传统方式相比速度提升46.50%,功耗为87.83 m W,面积为927.32×10^(3)μm^(2).展开更多
基金funded by the National Sciences Foundation of China(Grant No.91337103)the China Meteorological Administration Special Public Welfare Research Fund(Grant No.GYHY201406001)
文摘This study concerns a Ka-band solid-state transmitter cloud radar, made in China, which can operate in three different work modes, with different pulse widths, and coherent and incoherent integration numbers, to meet the requirements for cloud remote sensing over the Tibetan Plateau. Specifically, the design of the three operational modes of the radar（i.e., boundary mode M1, cirrus mode M2, and precipitation mode M3） is introduced. Also, a cloud radar data merging algorithm for the three modes is proposed. Using one month＇s continuous measurements during summertime at Naqu on the Tibetan Plateau,we analyzed the consistency between the cloud radar measurements of the three modes. The number of occurrences of radar detections of hydrometeors and the percentage contributions of the different modes＇ data to the merged data were estimated.The performance of the merging algorithm was evaluated. The results indicated that the minimum detectable reflectivity for each mode was consistent with theoretical results. Merged data provided measurements with a minimum reflectivity of -35 dBZ at the height of 5 km, and obtained information above the height of 0.2 km. Measurements of radial velocity by the three operational modes agreed very well, and systematic errors in measurements of reflectivity were less than 2 dB. However,large discrepancies existed in the measurements of the linear depolarization ratio taken from the different operational modes.The percentage of radar detections of hydrometeors in mid- and high-level clouds increased by 60% through application of pulse compression techniques. In conclusion, the merged data are appropriate for cloud and precipitation studies over the Tibetan Plateau.
文摘随着量子计算的发展,现有密码系统的安全性将受到严重威胁.Saber算法是抵御量子计算攻击的后量子密码方案之一,但存在多项式商环上模乘占据运算开销过大的问题.鉴此,本文通过对Karatsuba算法和Schoolbook相乘方式的剖析,提出一种面向Saber算法的并行乘法器设计方案.该方案首先利用Karatsuba算法分解模乘运算的关键路径,结合乘法复用和加法替换的策略减少硬件开销,然后采用并行运算电路压缩关键运算路径时长,最后在TSMC 65 nm工艺下,利用Modelsim和DC软件仿真验证.结果表明:该方案运算时长为137个时钟周期,与传统方式相比速度提升46.50%,功耗为87.83 m W,面积为927.32×10^(3)μm^(2).
文摘目的禽流感疫情的爆发和传播受到多种自然因素的影响。今欲尝试将地理信息系统与基因进化树分析相结合，以建立一种基于基因序列变异追踪中国禽流感病毒地理传播的技术。方法禽流感病毒基因来源于美国国立医学图书馆（National Library for Medicine，NLM）数据库，所获得的基因组数据利用E—Utilities软件包转化为结构体后，可用Matlab软件阅读。结构体主要字段包括PB2、PBl、PA、HA、NP、HA、M1和NSl8个片段，分别代表流感病毒的8个不同的基因片段。基于结构体字段，利用计算生物学的方法比较不同传播能力禽流感病毒的同义突变／非同义突变基因（Ka／Ks）比例，确定不同选择压力之下A型禽流感病毒的基因突变模式。进而选择Ka／Ks比例最大的基因片段，采用Jukes—Cantor算法估计氨基酸序列变异的进化距离，然后对不同爆发点的H5N1型禽流感进行进化树聚类。将聚类信息输入Google Earth，并利用不同图层地理信息对影响爆发点分布的因素做单因素分析。结果比较分析A型禽流感所有的8个基因序列可以看出，NSl、HA和NA蛋白的Ka／Ks比值较大。三者中，HA基因的Ka／Ks比值最大，可以代表病毒的传播能力。利用分级聚类的思路对HA基因转录的氨基酸相似程度进行比较，发现自2003年以来亚洲地区爆发的H5N1型禽流感之间的关系可以表示为一个由30个节点构成的进化树，其中14个节点为分支节点，16个节点为叶子结点。把分支树的前三个节点作为分类标准，可以把所有16个病毒株分为四类。这四类病毒在地理空间的分布呈现一定规律。计算发现禽流感爆发相关地理因素排序分别为：内陆水体〉主要铁路交通线〉家禽密度。结论对中国HSNl病毒株基因序列变异的地理分布分析显示，禽流感病毒爆发与候鸟迁徙、家禽运输密切相关。
