The DDoS Intrusion Detection System Based on High-speed Packet Capture Platform of Linux

在百兆环境下使用的Linux系统自带的Libpcap分组捕获函数库已经不能继续满足人们的需求，因为其“每包驱动”的特性在千兆环境下产生大量中断，造成中断淹没和丢包率急剧上升，引起系统瓶颈，若系统不改进，则会影响其他网络应用例如入侵检测系统、网络协议分析和网络防火墙的效率，变成千兆网络普及的阻碍。因此如何在千兆网络环境下实现线速的报文捕获以及上层的安全应用，一直是研究的热点。基于此，作者开展了本项研究，包括两方面内容。一方面，针对线速报文捕获问题，本文基于Linux平台，用零拷贝和内存映射等方法设计和实现了一个高速报文捕获平台，具有线速报文捕获、CPU占用率低和与Libpcap兼容的特点。另一方...The packet capture library of Libpcap in Linux that was used under Fast network can no longer meet people’s needs, since its ”every package-driven” features. Large numbers of interrupt were produced in Gigabit environment, leading to system bottlenecks such as livelock and high rate of packet loss. If the system does not improve, the efficiency of network applications such as intrusion detection s...学位：工学博士院系专业：信息科学与技术学院计算机科学系_计算机系统结构学号：2302007115130

Effects of Acid Extraction Parameters on Properties of Pectin from Pomelo Peel

作者简介：林晓锋(1986 —)，男，硕士研究生，研究方向为化学工程。E-mail：[email protected] 通信作者：许建中(1953 —)，男，高级工程师，研究方向为生物化工。E-mail：[email protected][中文文摘]选用福建特产琯溪蜜柚果皮为原料,考察酸提工艺条件对果胶的酯化度、黏均分子质量和半乳糖醛酸含量的影响,设计正交试验L9(34)考察各因素的影响。结果表明:在试验范围内,酸提工艺条件对果胶的酯化度基本无影响,对半乳糖醛酸的含量有明显的影响,对果胶的分子质量影响最显著。9个不同试验条件下,酸提果胶的酯化度63.5%～63.8%,半乳糖醛酸含量74.2%～88.5%,果胶的黏均分子质量101～202ku。[英文文摘]The effects of process parameters such as temperature,solid/liquid ratio,extraction time and pH for pectin extraction from Guanxi honey pomelo peel with dilute hydrochloric acid on degree of esterification(DE),viscosity-average molecular mass and galacturonic acid content of pectin were investigated using an L9(34) orthogonal array design.The results showed that the process parameters had little effect on pectin DH,remarkable effect on galacturonic acid content,and the largest effect on viscosity-average molecular mass and galacturonic acid content of pectin were investigated using an L9(34) orthogonal array design. The results showed that the process parameters had little effect on pectin DH, remarkable effect on galacturonic acid content, and the largest effect on viscosityaverage molecular mass. The 9 orthogonal array runs resulted in a DH of 63.5%-63.8%, a galacturonic acid content of 74.2%－88.5% and a viscosity-average molecular weight of 101－202 ku.福建省科技计划重点项目(2010Y0035

Research on DDoS Intrusion Detection System Based on Linux High Speed Packet Capturing Platform

如何在高速网络环境下实现线速的报文捕获以及上层的安全应用,一直是研究的热点。前期用内存映射和零拷贝等方法实现了基于千兆网卡的高速报文捕获平台nACP,在此基础上,通过使用IP地址的分布与系统资源的使用情况等作为检测参数,在SnOrT工具上实现了防ddOS攻击的入侵检测系统。在nACP上的实验表明,改进的ddOS入侵检测工具SnOrT与高速报文捕获平台兼容性良好,发生ddOS时能迅速检测到并且做出恰当的回应。由于使用了高速报文捕获平台,ddOS检测占用系统资源明显减少,很大程度上提高了系统的效率,系统可以在入侵检测的同时处理其他的事务。It has always been a hot research aspect to achieve wire-speed packet capturing and the upper security applications in gigabit network environment.In previous work,we created the high-speed Gigabit Ethernet packet capture platform NACP by using memory mapping and other methods.On this basis,by using the distribution of IP addresses and the use of system resources as detection parameters,we achieved the anti-DDoS attacks intrusion detection system based on snort tool.The experiments on NACP show that improved DDoS intrusion detection tool Snort is compatible with the high-speed packet capturing platform,and the event of DDoS can be quickly detected and get appropriate response in NACP.Because of the use of high-speed packet capturing platform,the system resources occupied by DDoS detection are significantly reduced,so it greatly improves the system efficiency,and the system can handle other affairs during the intrusion detection.国家自然科学基金(60903160); 中央高校基金(11D11209); 四川省科技支撑计划基金项目(2013GZ0016); 四川省教育厅重点项目(13ZA0296)资

Soil organic carbon sequestration rate and its influencing factors in

通过对甘肃省庄浪县梯田土壤采样分析,结合第二次土壤普查及庄浪县耕地质量评价数据,估算梯田土壤固碳速率并分析其影响因素。结果表明:1)该县农田土壤沟谷台地的有机碳含量最高,沟谷、梁峁坡地次之,沟谷川坪地有机碳最低,不同地形有机碳含量差异显著(P&lt;0.05);2)80%的样点土壤有机碳含量在6.0～11.0 g/kg之间,总体上0&mdash;20 cm农田土壤有机碳含量呈现正态分布,剖面有机碳含量从上至下呈逐渐递减规律;3)现阶段庄浪县0&mdash;20 cm农田土壤有机碳密度为20.02 t/hm2,低于全国耕层土壤有机碳密度平均水平(33.45 t/hm2),近30年0&mdash;20 cm土壤固碳速率为C 63 kg/(hm2.a),近5年固碳速率为C 26 kg/(hm2.a);4)在半干旱区县域尺度上,地形部位可解释43%的有机碳变异性,有机肥、坡向和田面坡度三者之和可解释47.1%的有机碳变异性,土壤类型可解释9.9%的有机碳变异性。综合分析表明,庄浪县农田土壤有机碳密度在过去30年间呈增加趋势,可能与庄浪县在60年代开始的大规模梯田建设和水土流失治理有关。</span

中国科学院力学研究所非线性国家重点实验室;清华大学工程力学系;

采用直接数值模拟计算了雷诺数Re_&Upsilon;=205的槽道湍流。并在此流动条件下,对泰勒冻结假设的有效性进行了测试。由于输运方程包含了泰勒假设项(时间导数项、流向方向的对流项),所以当输运方程的各附加项(例如,动量输运方程中的附加对流项、压力梯度项以及黏性项)或其和的值很大时,泰勒假设的有效性会降低。通过分别对动量输运方程和涡量输运方程中各附加项的分析,考察了泰勒假设在速度场以及在涡量场中有效性降低的范围,有效性降低的程度,以及各附加项对泰勒假设有效性降低的贡献程度。</p

Practice of quality control circle activities in improving the accuracy of inhalants usage in patients with chronic obstructive pulmonary disease (提高慢性阻塞性肺疾病患者吸入剂规范使用率的品管圈实践)

Objective To investigate the effect of quality control circle (QCC) activities in improving the accuracy of inhalants usage in patients with chronic obstructive pulmonary disease (COPD). Methods A QCC team was established to conduct problem-solving QCC activities. The current situation and factors of inhalants usage in COPD patients were analyzed. Targeted nursing countermeasures were carried out including comprehensive health education, standard operating procedure, enhanced training and evaluation, and diversified exercise of respiratory function. Results The accuracy rate of inhalants usage in COPD patients was increased form 58. 25% before implementation of QCC activities to 83. 06% after implementation of QCC activities. Conclusion The QCC is effective to improve the accuracy of inhalants usage in COPD patients. (目的 开展品管圈活动提高慢性阻塞性肺疾病(COPD)患者吸入剂的规范使用率。方法 成立品管圈圈组, 开展问题解决型品管圈活动, 通过现状把握、原因分析、制定了针对性的对策并予以实施, 包括打造无死角的宣教环境, 简单化、专业化、标准化完善操作流程, 加强培训夯实知识、质控考核提高水平和多元化、精细化进行呼吸功能锻炼。结果 COPD患者吸入剂的规范使用率由品管圈活动开展前的58. 25%上升至品管圈活动开展后的83. 06%。结论 品管圈活动能够提高COPD患者吸入剂的规范使用率。