口令重用行为与多维口令体系研究

互联网的迅速发展与网络服务的高度分散,促使广大网民不断注册更多的账户,并导致口令重用行为普遍化,使得用户信息面临泄露的风险。为此,基于2011年底互联网泄密门数据和大学生在线调查数据,分析了网民口令的结构特征和重用行为,并由此设计融入信息维度和分级管理思想的多维口令体系。该体系以根口令-重用码结构为基础,内容维包含多个独立的信息因子,构成口令的可记忆性主体;形式维负责形式变换,以提升口令的复杂性和安全性;时空维用于保障口令的时效性和重用性。对比量化分析结果表明,该口令体系具备良好的记忆性和便捷性,能有效抵御暴力攻击和熟人攻击。     

中空聚合物微球的制备Ⅲ.种子扩径的影响

以预乳化液连续滴加进料的三段乳液聚合结合碱酸溶胀处理制备了单分散性良好、大粒径的聚(甲基丙烯酸-甲基丙烯酸甲酯-丙烯酸丁酯)/聚(甲基丙烯酸-苯乙烯)中空聚合物微球。实验发现,在二段乳液聚合种子扩径中,种子乳胶粒数目、乳化剂用量、预乳化液滴加时间等对避免新乳胶粒的生成、扩大种子乳胶粒的粒径有影响,并找到了各自的较优值;扩径单体中的丙烯酸丁酯含量显著影响扩径乳胶粒聚合物的玻璃化温度,进而决定碱酸处理温度。     

Tocopherol oil concentration in field-grown sunflower is accounted for by oil weight per seed

Tocopherols are natural antioxidants that increase the stability of fat-containing foods and perform important biological activities. Significant variations (389 to 1873 μg g oil⁻¹) in the total tocopherol concentration of sunflower seed oil have been reported. The main objectives of this work were to determine the influence of intercepted photosynthetically active radiation on tocopherol concentration during seed filling and to establish and validate relationships between tocopherol concentration in oil and other quality variables of the seed. Seven sunflower hybrids were grown under good water and nutritional conditions in two similar experiments carried out in two contrasting environments. Treatments were applied to modify the amount of radiation intercepted per plant during seed filling in order to obtain a range in oil yield per plant and its components. Greater per plant intercepted radiation decreased the tocopherol concentration in oil. Tocopherol concentration decreased when oil weight per seed increased. Tocopherol concentration stabilized for oil weight per seed higher than 23 mg oil seed⁻¹. This exponential relationship accounted for 73% of the variability in tocopherol concentration (507 to 1203 μg g oil⁻¹) despite differences in hull type, locations, hybrids, and radiation treatments. The proposed relationship acceptably predicted independent results. Crop management techniques could lead to seeds with greater concentrations of tocopherols.     

微粒群优化和区域生长结合的彩色图像分割算法

提出了一种微粒群优化和区域生长相结合的彩色图像分割算法,以彩色图像直方图中自适应搜索到的峰值作为像素种子。由于搜索像素种子点是按密度进行,计算量小,大幅度提高了算法的计算速度,同时克服了传统区域生长方法不能自动选择种子且容易导致过分割的局限性。实验表明：该方法提高了图像分割速度,并可以准确地分割出目标,是一种有效的图像分割方法。     

Biodiesel development from high acid value polanga seed oil and performance evaluation in a CI engine

Non-edible filtered high viscous (72 cSt at 40 °C) and high acid value (44 mg KOH/gm) polanga (Calophyllum inophyllum L.) oil based mono esters (biodiesel) produced by triple stage transesterification process and blended with high speed diesel (HSD) were tested for their use as a substitute fuel of diesel in a single cylinder diesel engine. HSD and polanga oil methyl ester (POME) fuel blends (20%, 40%, 60%, 80%, and 100%) were used for conducting the short-term engine performance tests at varying loads (0%, 20%, 40%, 60%, 80%, and 100%). Tests were carried out over entire range of engine operation at varying conditions of speed and load. The brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) were calculated from the recorded data. The engine performance parameters such as fuel consumption, thermal efficiency, exhaust gas temperature and exhaust emissions (CO, CO₂, HC, NO_x, and O₂) were recorded. The optimum engine operating condition based on lower brake specific fuel consumption and higher brake thermal efficiency was observed at 100% load for neat biodiesel. From emission point of view the neat POME was found to be the best fuel as it showed lesser exhaust emission as compared to HSD.     

Chinese melon (Momordica charantia L.) seed: Composition and potential use

Chinese melon (Momordica charantia L.), also known as bitter gourd, is a tropical crop, grown throughout Asian countries for use as food and medicinals. In 1993, four cultivars of Chinese melon were grown in Mississippi and the seeds were collected. Oil contents of the seeds ranged from 41 to 45% and the oils contained 63–68% eleostearic acid and 22–27% stearic acid. Industrially important tung oil, a “fast-drying oil” used in paints and varnishes, contains 90% eleostearic and 2–3% stearic acid. The ratio of stearic to eleostearic in Chinese melon seed oil is ten times greater than that in tung oil. The higher ratio should reduce the rate of drying and crosslinking and could be advantageous in the paint industry. The defatted meals contained 52–61% protein and would be a good source of methionine.     

砾石土质条件下葡萄滴灌生育期土壤含水率变化规律研究

为探究酿酒葡萄在砾石土质条件下的土壤含水率变化规律及合理灌溉制度,选取贺兰山东麓砾石土典型试验区,以五年生赤霞珠品种为研究对象,设计2 550、2 850、3 225、3 600 m3/hm24个不同定额的灌水处理,应用TDR土壤水分剖面仪和土壤水势仪,监测生育期滴灌前后不同土层含水率与水势变化,针对监测数据从灌水处理整体与单个生育期不同角度进行分析,研究酿酒葡萄在砾石土条件下不同滴灌定额土壤含水率变化规律,最终提出生育期适宜灌溉制度。研究结果表明:随着灌溉定额的增加,土壤含水率在0~40cm土层范围内变化较明显;不同深度土层土壤水势变化规律与灌溉定额的大小有关;1m深土壤水分蓄存比并不是随着灌水量的增加而增大,而是当灌水量达到某一定额时,随着灌水量的增加,土壤水分蓄存比减小,砾石土单次灌水量高于300 m3/hm2时,土壤水分蓄存比较低,易产生深层渗漏。     

常压混合脱硅工艺生产种分精液

本文介绍了碳分、种分工艺对精液硅量指数A/S的不同要求,认为种分精液单独生产是很有必要的.本文从理论上分析了目前所应用的脱硅工艺,提出了一种常压生产种分精液的方法-常压混合脱硅工艺,并对某厂采用此工艺进行种分精液生产的情况进行了简单的介绍.     

Photochemical synthesis of bimetallic Au-Ag nanoparticles with "core-shell" type structure by seed mediated catalytic growth

The colloidal Au core/Ag shell structure composite nanoparticles were synthesized in PEG-acetone solution by photochemical route. The monodispersed Au nanoparticles with average diameter of 3.9 nm were used as growth seeds. The optical property of colloids and the sizes of composite nanoparticles were characterized when the molar ratio of Au to Ag ranges from 4 : 1 to 1 : 4. The results show that a composite nanoparticle structure similar to strawberry shape is formed at the molar ratio of Au to Ag from 4 : 1 to 1 : 1; the composite nanoparticles consisting of a core of Au and shell of Ag were generated at the 1: 4 molar ratio, having a striking feature of forming interconnected network structure.     

不同灌溉量对退化草地的生态恢复作用

在希拉穆仁草原进行了为期3年的草地灌溉试验,对测试的试验地在灌溉3年期间及停灌后1年内进行了植被调查和土壤种子库发芽试验,结果表明：一是灌溉可以明显提高草地植被的生产性能且不同灌溉量间并无明显差异。当停止灌溉后,原灌溉样地的植被生产性能均略低于无灌溉对照区,且不同灌溉量间也无明显差异。二是不同灌溉量样地植被物种组成与无灌溉对照区的Bray-curtis相似性系数始终保持在0.8左右,表明灌溉期间群落结构并未发生很大变化。当停止灌溉后,原灌溉样地与无灌溉对照区的Bray-curtis相似性系数下降为充足灌溉区0.61和中度灌溉区0.55,表明灌溉对植物的生存策略有一定的影响且不同灌溉量基本相同。三是土壤中的种子总数量有所增加,但物种的数量有所减少。充足灌溉样地土壤种子库情况略差于无灌溉对照区,中度灌溉样地则略好于无灌溉对照区,表明不同灌溉量对植物的繁殖策略有一定的影响。