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【客户案例】拉曼光谱结合K均值法检验手帕纸包装袋的研究
引言
手帕纸包装袋使用具有广泛性,其包装袋残片被遗留在案件现场的概率较大,弄清手帕纸的种属来源,能够提供使用人身份及活动路线信息,对案件推动具有重要作用。现场残留包装袋往往受环境因素影响,仅余部分残片,给追溯手帕纸的来源、品牌,实现检验分类设置了障碍,亟待开展进一步检验分析。
手帕纸由于生产厂家,合成工艺、商品化助剂添加及生产设备选取都存在一定偏差,不同品种的手帕纸塑料包装袋有不同物理及化学特征,这些差异均会使拉曼散射强度有所差异。因此采用拉曼光谱法可以有效的区分手帕纸外包装,从而为实际现场塑料物证检验提供了充分参考。
 

研究成果
近期,中国公安大学姜红教授团队基于Matlab进行拉曼数据预处理及相似度分析,结合K均值聚类法(K-means)对收集到的不同手帕纸小包装袋样本进行建模分析,可以获得合适的初始凝聚点数K,实现了手帕纸的区分检验。
手帕纸外包装袋为塑料,以树脂为主要原料,以增塑剂、填充剂、润滑剂、着色剂等添加剂为辅助成分通过高压合成的高分子化合物。包装袋主要填料为合成树脂,多为聚乙烯、聚氯乙烯或聚丙烯,常见塑料助剂为CaCO3、滑石粉和BaSO4。通过筛选我们发现依据填料种类可将样本分为三大类(见表3),第I类样品中主要填料为聚乙烯(如图2),第II类样品中主要填料为聚氯乙烯(如图3),第III类样品中主要填料为聚丙烯(如图4).

 
表3 手帕纸塑料包装袋样品分类
 
图2 第I类样品的拉曼光谱图


图3 第II类样品的拉曼光谱图
 
图4 第III类样品的拉曼光谱图

 
首先基于主成分分析法(principle component analysis,PCA)进行数据预处理,以实现数据降维,提升分析准确性,从总体协和方差矩阵出发进行主成分分析。选取分类贡献率大于百分之一的PC1、PC2、PC3作为主特征,以待后续验证分析。作为快速聚类法,K均值聚类法不需预知样本种数,可对K值进行迅速演算并反馈样本吻合度,最终筛选出合适K值,同时实现样本分类。本次结合kmeans函数及silhouette函数分别对三大类样品进行进一步分类,数据准确性达93%。结合K均值聚类法,基于已知样本标准数据,可实现对未知样本的快速分类和高效鉴定,分类成功率达97.14%。
该方法操作简便、精确度高,将计算机软件技术和光谱检测技术相结合,相较传统的谱图分析法更加快速准确,数据处理效率更高,为实际应用提供了充分参考。对信噪比较高的样本数据也可实现迅速分类,背景容错率好,可在公安实践中对现场不易分类的局部手帕纸外包装袋进行检测分类,为实际办案中划定嫌疑人活动轨迹、侦破案件提供线索,为刑事诉讼提供合法证据。

文章信息:
该成果近期以“拉曼光谱结合K均值法检验手帕纸包装袋的研究”为题发表在期刊上,该工作由中国公安大学姜红课题组完成,论文链接如下:http://www.cnki.com.cn/Article/CJFDTotal-GSSX201902009.htm
本研究采用的是北京卓立汉光仪器有限公司“Finder Vista”激光显微共聚焦拉曼光谱系统,如需了解该产品,欢迎咨询我司。
 

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北京卓立汉光仪器有限公司官方所发布内容、图片及数据来源于原作者提供或原文授权转载。文章版权、数据及所述观点归文章作者和文章出处所有。
卓立汉光力求数据严谨准确,如有失误失实敬请指正。如涉及版权等问题,请您来电或来函联系,我们将协调给予处理。

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Countertop Display Racks

Countertop Display Racks

Capitalize on Limited Space with Countertop Displays

When space is at a premium, retail counter displays help ensure every square foot earns its keep. For gift and souvenir shops, these compact racks are perfect for showing off limited collections. In addition, small, promotional, or seasonal items displayed near the cash register can significantly increase impulse buys. Durably built and available in a variety of styles, table top displays are available to hold everything from candy to clothing.
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When customers walk through your store, where is it that they spend the most time? Chances are, if your store is like many others, they’re spending that time lingering around countertops: the checkout counter, the display counter where employees work the most often, and other counters where they are most likely to interact with your employees. If you aren’t taking advantage of that valuable space to market impulse purchases, you’re missing out on a great chance to increase the value of every customer’s visit to your store!

Countertop displays have a number of advantages. They’re small, portable, and easy to change out based on the changes of seasonal merchandise, the unique needs of your customers, or the items that you most need to display at any given moment. Not only that, they’re typically placed in locations that are under heavier supervision by your employees, making it easier for you to keep an eye on small items that are most often targets for thieves.

When you choose a countertop display for your business, there are a number of elements that you want to consider. Of course, you want to design a display that is eye-catching and intriguing, but not too cluttered. By considering the right elements, you can be sure that the countertop display you’ve chosen fits your needs.

Element One: Your available space. You don’t want to over-crowd your countertop with too many items. Not only will it lead to mental overload for most of your customers, it will prevent them from using the countertop for other purposes: filling out checks, signing receipts, or taking care of other business. Instead, choose a countertop display that can be placed in an area that is highly visible, but that won’t cause problems for your customers when they need the space.

Element Two: Your products. Your products have a serious impact on which countertop display you need. How big are the products that you’d like to display? While small items like sunglases  are often most beneficial as impulse purchases and a sunglasses countertop rack should be used, a smaller number of larger items can also be displayed. You just need to make sure they fit on your rack! You’ll also need to know how heavy your items are: light duty racks are perfect for holding lightweight items while medium duty racks can hold heavier items.

Element Three: Your vision. What do you want out of your countertop display? From peg and hook spinners to baskets and jars, wire panels, or clip strips, you can choose a countertop display that will mesh with your vision for your store. The products you choose and the available space will help determine which one is right for you, but keeping your vision and theme in mind is also paramount!

Countertop displays are prime retail space in your store. This is your opportunity to interest customers in exactly the products you most want to sell, letting them take a longer look while they wait for other customers or employees to take care of their current tasks. Don’t let this vital piece of space go to waste!