Perceptual encryption with compression for secure vector map data processing

With the rapidly rising interest in geographic information system (GIS) contents, a large volume of valuable map data has been unlawfully distributed by pirates. Therefore, the secure storage and transmission of classified national digital map datasets have been increasingly threatened. As the importance of secure, large-volume map datasets has increased, vector map security techniques that focus on secure network and data encryption have been studied. These techniques are required to ensure access control and prevent illegal copying of digital maps. This paper presents perceptual encryption on the vector compression domain for copy protection and access control of vector maps. Our algorithm compresses all vector data of polylines and polygons by lossless minimum coding object (MCO) units and perceptually encrypts using two processes using the mean points and directions of MCOs. The first process changes the position of vector data by randomly permuting the mean points of MCOs, the so-called position encryption. The second process changes the geographic shape by circularly encrypting the directions of vertices in MCOs by the XOR operator. Experimental results have verified that our algorithm can encrypt GIS digital maps effectively and simply and can also improve the compression ratio, unlike general data encryption techniques, and thus, our algorithm is very effective for a large volume of GIS datasets.     

QuEChERS-超高效液相色谱-串联质谱法测定柑橘中呋虫胺和螺虫乙酯残留量

目的建立QuEChERS-超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)同时测定柑橘中咲虫胺及螺虫乙酿残留量的分析方法。方法样品采用QuEChERS方法,经1%甲酸乙腈涡旋振荡提取,无水硫酸镁和氯化钠盐析后,经乙二胺-N-丙基硅烷、C_(18)混合净化剂净化,用Waters ACQUITY UPLC HSS T_3色谱柱分离,超高效液相色谱-串联质谱正离子扫描、多反应监测模式进行测定,外标法定量。结果呋虫胺及其代谢物、螺虫乙酯及其代谢物在相关浓度范围内线性关系良好,相关系数均大于0.99。呋虫胺及其代谢物的回收率为86.8%～97.6%,相对标准偏差为2.7%～6.8%,方法定量限为0.005～0.01 mg/kg;螺虫乙酯及其代谢物的回收率为85.8%～96.9%,相对标准偏差为3.2%～7.4%,方法定量限为0.005～0.008 mg/kg。结论该方法样品前处理过程简单快速,分析时间短,定量限低、正确度及精密度均符合农药残留检测要求,适用于同时测定柑橘中呋虫胺和螺虫乙酯残留。     

超高效液相色谱-串联质谱法测定干辣椒中2种新型杀虫剂残留量

目的 建立超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)测定干辣椒中氰氟虫腙和氯虫苯甲酰胺残留量的分析方法。方法 干辣椒样品经乙腈匀浆提取, 氨基固相萃取小柱净化, 甲醇/水(50:50, V:V)定容, 以反相C18色谱柱(100 mm×2.1 mm, 1.7 μm)分离, 0.1%甲酸-水和甲醇作为流动相进行梯度洗脱, 多反应监测模式下进行超高效液相色谱-串联质谱测定、基质匹配标准溶液外标法定量。结果 2种新型杀虫剂在5~500 μg /L范围内线性关系良好, 相关系数均大于0.999, 定量限为0.008~0.01 mg /kg; 在高、中、低3个加标水平下的回收率为80.4%~94.9%, 相对标准偏差在0.9%~8.7%之间。结论 方法简单、快速、灵敏高、准确可靠, 可操作性强, 适合测定干辣椒中氰氟虫腙和氯虫苯甲酰胺残留量。