40 research outputs found
Design and Implementation of the Online Shopping System Based on PHP & MySQL
网上购物系统是指在网络上建立一个虚拟的购物商场,使购物过程变得轻松、快捷、方便,很适合现代人快节奏的生活;同时又能有效的控制“商场”运营的成本,开辟了一个新的销售渠道。本文利用PHP+MySQL进行程序设计和数据库设计,使用Apache平台,完成网上购物系统的设计与实现。通过搭建该购物平台,学习和掌握电子商务的网上购物系统是如何通过在本系统中完成注册后直接在线进行物品的买卖,可以提高物品的流通和购物的效率,为用户节约了往返于门市之间的时间,同时因为是在网络虚拟环境下进行的,也为网上购物系统的需求方节约了人力物力,真正做到省时高效。 该系统主体部分包括前台功能模块和后台功能模块。前台功能主要包...Online shopping system is an application of network for convenient shopping, making shopping an exciting and direct experience in an easy and fast way to cope with quick-paced lifestyle. It works efficiently to control business cost and exploits a new sales channel. This dissertation is to explain the work on setting up an online shopping system based on the Apache platform, by designing the relev...学位:工程硕士院系专业:软件学院_工程硕士(软件工程)学号:X200823010
Remote Sensing Image Enhancement Based on Orthogonal Wavelet Transformation and Pseudo-color Image Processing
针对基于正交小波分析的图像增强技术一般只适用于黑白图像;而伪彩色处理技术不能够充分处理图像中某些细节信息的缺陷,提出了基于正交小波分析和伪彩色的遥感图像增强处理方法;实验结果表明,增强后的遥感图像无论在视觉效果上还是在噪声特性上都有了很大的改善;该方法简便易行且计算量小,在应用中有较大的灵活性;该方法还具有运算速度快和可操作性强等特点,在遥感图像增强研究方面具有广泛的应用前景。Image enhancement technique based on wavelet analysis is only applicable to black-and-white image,and pseudo-color image processing technology can not adequately deal with some of the details information of the image.In this paper,enhancement approach of remote sensing image based on orthogonal wavelet analysis and pseudo-color image processing is put forward.Enhanced remote sensing image have been greatly improved in both visual effects and noise characteristics.The method is simple to implement,and need less calculation,and its application is more flexible.This method also has the characteristics of faster computing speed and operating feasibly and so on.It has broad application prospects in research of remote sensing image enhancement.国家自然科学基金项目(60873179);广西教育厅科研项目(200707LX196
Design of Carrier Synchronization Based on Costas Loop
介绍了平方变换法相干解调原理,从工程角度完善了载波提取的电路结构,消除了频移载波的误锁问题.提出用科斯塔斯环法来实现从2dPSk信号中提取相干载波,解决了提取的载波信号存在180度的相位含糊问题,为通信系统提高抗噪性能提供了条件.当载波频率很高时,工作频率较低的科斯塔斯环易于实现.并用SIMulInk设计出科斯塔斯环法提取载波的仿真电路图和进行相应的仿真实验.Theory of coherent demodulation based on method of square counterchange is introduced in this article.The structure of circuit for carrier recovery is perfected in engineering,and the problem of error-lock for frequency-shift carrier is eliminated.Costas Loop is put forward to achieve coherent carrier from 2DPSK signal in this article.The 180° phase's inexplicit problem which exist in carrier recovery is resolved.It improves the resisting noise property of communication system.When carrier frequency is higher,Costas loop is easy to implement carrier synchronization.Because the operating frequency of Costas loop is lower than square PLL.We scheme out emulational circuit diagram for carrier distilling with Costas loop by using simulink and process corresponding emulational experiment.国家自然科学基金项目(60873179);广西教育厅科研项目(200707LX196
Compressed Storage for C-Temporal Relation Data Model Based on Improved Genetic Algorithm
针对时态数据库中存在数据冗余、数据量快速增长等问题,结合现有压缩技术,提出基于改进遗传算法的C-TrdM压缩存储技术。将各个时刻的时态关系数据分解为最小粒度的数据并进行编码,采用改进的遗传算法来计算待压缩数据中的最优存储数据以提高压缩比。算法的快速收敛性使去除数据冗余的速度得到提高。There is data redundancy temporal database and the quantities of temporal database are increasing fleetly,aiming at these problems,this paper puts forward compressed storage tactics based on improved genetic algorithm for temporal data which combine compress technology in existence in order to settle data redundancy in the course of temporal data storage.Temporal relation data at any moment is decomposed into least granularity data and be coded meanwhile.Optimized storage data are figured out by using improved genetic algorithm,and the ratio of compression is enhanced.Celerity astringency of the algorithm can heighten speed of removing data redundancy largely.广西教育厅科研基金资助项目(200707LX196);广西工学院自然科学基金资助项目(院科自0704102
A quickly-speed running watermarking algorithm based on quantum evolutionary algorithm
针对传统基于人类视觉系统特性的空间域与变换域相结合的水印算法中嵌入信息量小、嵌入位置定位及检测准确率低和算法运行速度慢等缺陷,提出并实现一种基于量子进化算法(QEA)的快速水印新算法。仿真实验结果表明,新算法不仅生成水印图像的速度快,而且对各种攻击具有良好的敏感性和鲁棒性。新算法在应用中有较大的灵活性,并且具有可嵌入信息容量大、运算速度快和可操作性强等特点。There are limitations such as smaller embedded information capacity,lower accurate rate for positioning embedded location and detection and slower running speed in traditional watermarking algorithm which combines spatial domain and transform domain based on characteristics of human visual system.A quickly-speed running watermarking algorithm based on quantum evolutionary algorithm is proposed and implemented.The simulation results show that the proposed algorithm owns not only faster watermark image generation,but also have good sensitivity and robustness for all kinds of attacks.The proposed algorithm is more flexible in application,and it can embed more information and improve the computing speed.The method can be easily operated.国家自然科学基金资助项目(60873179);广西教育厅科研资助项目(200707LX196
High efficient and secure group key management scheme based on optimized GDH
针对gdH(grOuP dIffIE-HEllMAn)方案中节点可能成为系统的瓶颈以及计算复杂度、通信代价和存储复杂度远高于某些集中式方案等缺陷,提出并实现了一种基于优化gdH协商的高效安全的动态群组密钥管理方案,并对其安全性进行了证明。通过对计算量和通信量进行分析比较表明,优化gdH协商协议具有很大的优势,并且能够快速产生或更新组密钥,具有很强的实用性。There are some defects in GDH(group diffie-hellman) scheme,such as the node that may become the bottleneck of the system,and the computational complexity,cost of communications and storage complexity that are much higher than some centralized group key management program.An efficient and secure dynamic group key management scheme based on optimized GDH is proposed and implemented and its security is proven.The optimized GDH consensus agreement has great advantage than GDH by comparing and analysing the volume of calculating and traffic.At the same time,the optimized GDH consensus agreement can quickly produce and update group key,and it owns highly practicability.国家自然科学基金资助项目(60873179);广西教育厅科研资助项目(200707LX196
Multiresidue Determination of Organophosphorus Pesticide Residues in Vegetables and Fruit by Gas Chromatography-Negative Ion Chemical Ionization-Mass Spectrometry
将气相色谱-负离子化学电离质谱法(GC-NC I-M S)应用于蔬菜水果中9种有机磷农药残留的分析测定,初步解析了这些农药的NC I-M S特征阴离子结构和断裂机理,并初步探讨了GC-NC I-M S分析蔬菜水果中有机磷农药残留时基体效应的影响。采用空白样品基体匹配校准曲线法(M C)进行定量分析,有效地降低了基体效应的影响。蔬菜水果样品用乙酸乙酯超声提取,以乙硫磷为内标物,采用GC-NC I-M S的选择离子监测方式(S IM)进行定性和定量分析。9种有机磷农药的方法检测限为0.12~1.0μg/kg。在方法的检测限与1 000μg/kg范围内,线性相关系数都大于0.999 3。当空白蔬菜水果(西红柿)样品的加标水平为100,400,800μg/kg时,平均加标回收率为78%~126%,相对标准偏差为0.58%~14.7%。An analytical method of gas chromatography coupled with negative ion chemical ionization-mass spectrometry for simultaneous determination of nine organophosphorus pesticide residues in vegetables and fruit has been developed,and the negative ions structure and partition mechanism of the nine organophosphorus pesticides were interpreted.Meanwhile,the matrix effect for sample analysis was discussed,and matrix-matched calibration for quantification was introduced to reduce the matrix effect in this method.Pesticides were extracted from sample with ethyl acetate in an ultrasonic bath,then determined by gas chromatography-mass spectrometry operated in negative chemical ionization mode and quantified in selective ion monitoring mode,and ethion was used as an internal standard.The detection limits of the method were 0.12-1.0 μg/kg for the nine organophosphorus pesticides,and the relative coefficients were higher than(0.9993).A blank sample(tomato) was spiked at 100,400,800 μg/kg for each pesticide,and the recoveries were determined to be from 78% to 126% with relative standard deviations from 0.58% to 14.7% for the pesticides
The Restoration of Degraded Ecosytem in Hunshandak Sandland through Natural Process
浑善达克沙地是我国四大沙地之一,地处北方干旱半干旱区,为草原区向荒漠区过渡的地带。长期以来,由于人类不合理的生产活动,加上这里脆弱的生态环境,已引起了严重的土地退化问题:流动沙丘面积由1950s年占沙地总面积的2%增加到1990s的近50%。因此浑善达克沙地成为我国研究土地退化、防治沙尘暴的重点地区,本文从自然科学和人文科学相结合的角度出发,对浑善达克沙地草地退化原因、自然恢复潜力、恢复过程、适宜物种选择,以及社区生存、生产等方面进行了综合研究,得出以下主要结论:
1) 浑善达克沙地土壤种子库中含有大量的种子,在退化草地自然恢复中表现出极大的潜力。这些种子在摆脱人和牲畜干扰的前提下,可以萌发、定居并形成植物群落,使退化草地恢复;当地表达到一定程度的植被覆盖,可有效减少沙尘暴的危害。土壤种子库中的植物种类与地上植被有极显著的相似性(P<0.05),这是地上植被形成稳定群落的基础。种子库中的物种组成影响植被恢复演替的进程;反之,恢复演替也制约着种子库组成和幼苗建立。
2)退化沙地草地围封后,对不同恢复阶段草地的群落学调查表明,该地区自然恢复过程大致分为3个阶段:围封2年的恢复早期,流动沙丘向半固定沙丘转变;围封3-5年的恢复中期,半固定沙丘向固定沙丘转变;围封6年后的恢复后期,为固定沙丘稳定发展阶段。根据生活型及植物种类随恢复演替的变化规律,浑善达克沙地植被演替的总体趋势可归纳为:沙米 (Agriophyllum squarrosum)+ 雾冰藜(Bassia dasyphylla)群落→黄柳(Salix gordejevii)+ 冰草(Agropyron cristatum)群落→褐沙蒿(Artemisia intramongolica) + 冰草群落→沙地榆(Ulmus pumila var. sabulosa)疏林+冰草群落。在围封禁牧下,浑善达克退化沙地草地在较短时间内实现自然恢复,因此制约退化草地恢复演替的关键因素主要是人为和牲畜的干扰,只要排除了这种干扰因素,浑善达克大面积的退化沙地草地完全能够借助自然力实现生态恢复。
3) 浑善达克沙地3种生境下84种植物叶片渗透势值和含水量,表现出不同功能型上的差异。总体变化趋势为: 深根系 > 浅根系;灌木 > 乔木 > 草本;分布在湿地和丘间低地的植物叶片渗透势和含水量较高,而生长在沙丘上的植物叶片渗透势较低,需要有发达的根系吸收土壤深层的水。不同植物具有独特的水分利用特性,使它们能共存于同一生态系统中。这些不同植物功能型表现出的植物水分生理生态特性,表明浑善达克天然分布的植物群落发育有完善的利用水资源的能力,能够保证在很大降水波动条件下分布有丰富的植物群落和较高的生物生产力,构成该特殊类型生态系统很强的恢复潜力。另外,浑善达克沙地沙丘的存在是该类生态系统恢复弹性较高的另一重要原因。
4)本地种与引入种在生理生态上表现出不同的适应能力。在相似的太阳辐射和叶片温度下,引入种旱柳的叶片水势较高,而净光合速率、气孔导度、水分利用效率则较低。这表明它的光合潜能在改变环境中没有正常发挥。同时,引入种较低的最大光化学效率进一步表明它抵抗环境胁迫的能力较低。当土壤水分可利用程度降低而导致水分竞争时,引入种很可能在竞争中被淘汰。因此,在生态恢复中,应尽量避免引入外来种,大量使用本地种。
5) 生态恢复不仅是自然科学问题,更重要的是社会经济问题。为了充分认识当地社区的参与对生态恢复的作用,在实验过程中,调查了当地居民自本实验开展以来的思想观念、经济收入和生产效益等变化。在生态恢复中当地社区的积极参与是保证恢复成功与否的关键因素。从发挥“自然力” 和“以人为本”的指导思想出发,在生态恢复中应注重充分利用自然的力量;在管理方面,要以解决社区居民的生产生活实际需求为目标。只有这样,才能保证生态、社会和经济可持续发展
凝结水对干旱胁迫下羊草和冰草生理生态特征及叶片形态的影响
为了探讨凝结水对植物生长的作用,该文研究了干旱处理下模拟凝结水对羊草(Leymus chinensis)和冰草(Agropyron cristatum)生理性状和叶片表面结构的影响。试验设计了干旱无凝结水、干旱每周发生3次和5次凝结水以及正常浇水不发生凝结水4个处理,通过超声波加湿器模拟凝结水的发生,研究凝结水对两种植物叶片相对含水量、水势、净光合速率、水分利用效率、生物量以及叶片表面结构等的影响。结果表明:凝结水显著增加了干旱胁迫下两种植物的叶片相对含水量和水势(p<0.05);凝结水显著提高了冰草的净光合速率、气孔导度与蒸腾速率(p<0.05);而羊草的气孔导度和蒸腾速率随凝结水的变化不明显。羊草和冰草的地上生物量和根系生物量随凝结水的发生有增加的趋势,但是各处理间差异不显著。凝结水降低了羊草和冰草黄叶数与总叶数的比值,这表明凝结水对干旱胁迫下植物叶片表面结构遭到的破损有一定的保护和修复作用。该研究证实羊草和冰草的叶片可以吸收凝结水,并对其光合作用、水分生理以及生长具有正效应
