增强法制观念,提高档案意识：从一起丢失档案事件引发的思考

增强法制观念，提高档案意识从一起丢失档案事件引发的思考王晋华（山西省气象档案馆０３０００６）任爱萍（山西省气象台０３０００６）气象档案是国家全部科技档案资源的重要组成部分。气象记录档案又是气象档案的核心，是广大气象工作者，在观测、探测过程中所积累的，...     

一种针对规则冲突的规则集语义比较算法

应用DFD(Diverse Firewall Design)方法进行防火墙规则集设计时,需使用规则集语义比较算法,判断多个规则集是否语义一致。规则冲突是导致规则集语义不一致的主要原因。因此,需要研究针对规则冲突的规则集语义比较算法。而现有算法时空复杂度较高,性能低下。文中提出了1种基于关键数据包选取映射的规则集语义比较算法(KPCM)。KPCM算法针对规则冲突选取关键数据包,并通过比较这些数据包在不同规则集中的处理动作,判断这些规则集是否语义一致。理论分析和测试表明,KPCM算法时空性能均优于现有算法。     

基于DEA和SFA的我国海水养殖技术效率

文章采用2005—2015年我国沿海地区的面板数据,运用数据包络分析(DEA)和随机前沿分析(SFA)方法对海水养殖技术效率进行测度,并系统分析海水养殖技术效率的影响因素和意义。研究结果表明:我国海水养殖投入和产出水平较合理,但投入资源的优化配置仍有不足;海水养殖面积、海水养殖人员数量和中间物质消耗对海水养殖产量有显著的正相关影响,投入的鱼苗数对产量的影响不显著;运用DEA和SFA方法测度海水养殖技术效率存在显著相关性和差异性,在排序上存在显著一致性;海水养殖技术水平、海水养殖结构、机动渔船比例、海水养殖产值水平和海水养殖规模与海水养殖技术效率呈显著正相关,海产品加工水平呈正相关但不显著;研究海水养殖技术效率对海水养殖产业的发展具有重要意义。最后,基于海水养殖技术效率的影响因素提出相关建议。     

A study of internal solitary waves observed on the continental shelf in the northwestern South China Sea

Based on in-situ time series data from the acoustic Doppler current profiler (ADCP) and thermistor chain in Wenchang area, a sequence of internal solitary wave (ISW) packets was observed in September 2005, propagating northwest on the continental shelf of the northwestern South China Sea (SCS). Corresponding to different stratification of the water column and tidal condition, both elevation and depression ISWs were observed at the same mooring location with amplitude of 35 m and 25 m respectively in different days. Regular arrival of the remarkable ISW packets at approximately the diurnal tidal period and the dominance of diurnal internal waves in the study area, strongly suggest that the main energy source of the waves is the diurnal tide. Notice that the wave packets were all riding on the troughs and shoulders of the internal tides, they were probably generated locally from the shelf break by the evolution of the internal tides due to nonlinear and dispersive effects.     

1901-1995年气候变化导致陆地生态系统净吸收碳

The spatial and temporal variability of land carbon flux over the past one hundred years was investigated based on an empirical model directly calculating soil respiration rate. Our model shows that during 1901-1995, about 44-89 PgC (equals to 0.5, 0.9 PgC/yr respectively) were absorbed by terrestrial biosphere. The simulated net ecosystem productivity (NEP) after the 1930s was close to the estimated value of" missing C sink” from deconvolution analysis. Most of the total carbon sink happened during 1951-1985 with the estimated value of 33-50 PgC. Three major sinks were located in the tropics (10°S-10°N), Northern mid-latitudes (30°-60°N) and Southern subtropics (10°-40°S). During 1940s-mid-1970s, carbon sinks by terrestrial ecosystem increased with time, and decreased after the mid-1970s. These may be due to the ch anging of climate condition, as during the 1940s-1970s, temperature decreased and precipitation increased, while after the mid-1970s, an opposite climate situation occurred with evident increasing in temperature and decreasing in precipitation. Usually, warmer and dryer climate condition is not favor for carbon absorption by biosphere and even induces net carbon release from soil, while cooler and wetter condition may induce more carbon sink. Our model results show that the net carbon flux is particularly dependent on moisture / precipitation effect despite of temperature effect. The changing of climate in the past century may be a possible factor inducing increases in carbon sink in addition to CO2 and N fertilizer.     

后门检测系统的Win32应用程序设计与实现

介绍了后门检测系统的设计,以及各模块实现拟采用的方案,包括:网卡数据包的截获,进程和端口号的映射,截获包的解码与分析和数据库设计等.     

2001-2010年中国区域旅游效率评估

选择旅游酒店数、旅行社数、旅游酒店从业人员数和旅行社从业人员数为旅游投入因素,旅游总收入为产出变量,运用数据包络分析方法中的 C2 R 模型分析2001-2010年中国区域旅游效率及其空间格局和变化趋势。中国四大区域的平均旅游效率由高至低依次为东部地区、东北地区、中部地区和西部地区。在31个中国大陆省级行政区中,天津在2001-2010年期间每年都为旅游效率最高的省份。从时间的角度,中国区域旅游效率经历了一个波浪式变化过程,2003年和2008年是2个明显的波谷。2001-2005年四大区域旅游效率的变化过程基本一致。2005-2010年四大区域旅游效率变化各不相同,东部地区呈逐步下降趋势,中部地区先增长、2010年开始下降,西部地区为起伏不定,东北地区为持续增长。     

星地测量数据部分丢失对卫星钟差预报精度的影响

本文研究了不同的测量数据丢失概率对卫星钟差预报精度的影响,给出了卫星钟差的3阶白噪声状态方程和基于星地无线电双向时间比对的测量方程,得到了类似于Kalman滤波器的递归形式和修正Riccati方程;随着时间的推进,修正Riccati方程的预测误差逐渐减小,直至达到稳态;并根据修正Riccati方程,采用数值分析方法得到了典型参数情况下卫星钟差预报精度与测量数据有效率的关系曲线。