1、中文 4250 字 （ 二 一 年 月 本科毕业设计 外文文献及翻译 学校代码： 10128 学 号： 英文题目 ： Testing ZigBee Motes for Monitoring Refrigerated Vegetable Transportation under Real Conditions 中 文 题 目 ： ZigBee 检测探头在冷藏蔬菜运输现实条件下的测试 学生姓名 ： 学 院 ： 信 息 工 程 学 院 系 别： 电 子 信 息 工 程 专 业： 班 级： 指导教师 ： 教授 Abstract Quality control and monitoring of per
2、ishable goods during transportation and delivery services is an increasing concern for producers, suppliers, transport decision makers and consumers. The major challenge is to ensure a continuous cold chain from producer to consumer in order to guaranty prime condition of goods. In this framework, t
3、he suitability of ZigBee protocol for monitoring refrigerated transportation has been proposed by several authors. However, up to date there was not any experimental work performed under real conditions. Thus, the main objective of our experiment was to test wireless sensor motes based in the ZigBee
4、/IEEE 802.15.4 protocol during a real shipment. The experiment was conducted in a refrigerated truck traveling through two countries (Spain and France) which means a journey of 1,051 kilometers. The paper illustrates the great potential of this type of motes, providing information about several para
5、meters such as temperature, relative humidity, door openings and truck stops. Psychrometric charts have also been developed for improving the knowledge about water loss and condensation on the product during shipments. 1. Introduction Perishable food products such as vegetables, fruit, meat or fish
6、require refrigerated transportation. For all these products, Temperature (T) is the most important factor for extending shelf life, being essential to ensure that temperatures along the cold chain are adequate. However, local temperature deviations can be present in almost any transport situation. R
7、eports from the literature indicate gradients of 5 C or more, when deviations of only a few degrees can lead to spoiled goods and thousands of Euros in damages. A recent study shows that refrigerated shipments rise above the optimum temperature in 30% of trips from the supplier to the distribution c
8、entre, and in 15% of trips from the distribution centre to the stores. Roy et al. analyzed the supply of fresh tomato in Japan and quantified product losses of 5% during transportation and distribution. Thermal variations during transoceanic shipments have also been studied. The results showed that
9、there was a significant temperature variability both spatially across the width of the container as well as temporally along the trip, and that it was out of the specification more than 30% of the time. In those experiments monitoring was achieved by means of the installation of hundreds of wired se
10、nsors in a single container, which makes this system architecture commercially unfeasible. Transport is often done by refrigerated road vehicles and containers equipped with embedded cooling systems. In such environments, temperatures rise very quickly if a reefer unit fails. Commercial systems are
11、presently available for monitoring containers and trucks, but they do not give complete information about the cargo, because they typically measure only temperature and at just one point. Apart from temperature, water loss is one of the main causes of deterioration that reduces the marketability of
12、perishable food products. Transpiration is the loss of moisture from living tissues. Most weight loss of stored fruit is caused by this process. Relative humidity (RH), T of the product, T of the surrounding atmosphere, and air velocity all affect the amount of water lost in food commodities. Free water or condensation is also a problem as it encourages microbial infection and growth, and it can also reduce the strength of packaging materials. Parties involved need better quality assurance methods to satisfy customer demands and
