zigbee检测探头在冷藏蔬菜运输现实条件下的测试.doc
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1、中文4250字学校代码: 10128学 号: 本科毕业设计 外文文献及翻译(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: 教授二 一 年 月AbstractQuality control and monitoring of perishable goods during transportation an
2、d 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, the suitability of ZigBee protocol for
3、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/IEEE 802.15.4 protocol during a real
4、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 parameters such as temperature, relative h
5、umidity, 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. IntroductionPerishable food products such as vegetables, fruit, meat or fish require refrigerated transportation. For
6、 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. Reports from the literature indicate grad
7、ients 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 centre, and in 15% of trips from the dist
8、ribution 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 there was a significant temperature vari
9、ability 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 sensors in a single container, which makes
10、 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 presently available for monitoring contai
11、ners 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 perishable food products. Transpiration is
12、 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
13、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 to create a competitive point of difference. Successful transport in food logistics calls for automated and
14、efficient monitoring and control of shipments. The challenge is to ensure a continuous cold chain from producer to consumer in order to guaranty prime condition of goods . The use of wireless sensors in refrigerated vehicles was proposed by Qingshan et al. as a new way of monitoring. Specialized WSN
15、 (Wireless Sensor Network) monitoring devices promise to revolutionize the shipping and handling of a wide range of perishable products giving suppliers and distributors continuous and accurate readings throughout the distribution process. In this framework, ZigBee was developed as a very promising
16、WSN protocol due to its low energy consumption and advanced network capabilities. Its potential for monitoring the cold chain has been addressed by several authors but without real experimentation, only theoretical approaches. For this reason, in our work real experimentation with the aim of explori
17、ng the limits of this technology was a priority.The main objective of this project is to explore the potential of wireless ZigBee/IEEE 802.15.4 motes for their application in commercial refrigerated shipments by road. A secondary objective was to improve the knowledge about the conditions that affec
18、t the perishable food products during transportation, through the study of relevant parameters like temperature, relative humidity, light, shocking and psychrometric properties.2. Materials and Methods2.1. ZigBee MotesFour ZigBee/IEEE 802.15.4 motes (transmitters) and one base station (receiver) wer
19、e used. All of them were manufactured by Crossbow. The motes consist of a microcontroller board (Micaz) together with an independent transducer board (MTS400) attached by means of a 52 pin connector. The Micaz mote hosts an Atmel ATMEGA103/128L CPU running the Tiny Operating System (TinyOS) that ena
20、bles it to execute programs developed using the nesC language. The Micaz has a radio device Chipcon CC2420 2.4 GHz 250 Kbps IEEE 802.15.4. Power is supplied by two AA lithium batteries.The transducer board hosts a variety of sensors: T and RH (Sensirion SHT11), T and barometric pressure (Intersema M
21、S5534B), light intensity (TAOS TSL2550D) and a two-axis accelerometer (ADXL202JE). A laptop computer is used as the receiver, and communicates with the nodes through a Micaz mounted on the MIB520 ZigBee/USB gateway board.Each Sensirion SHT11 is individually calibrated in a precision humidity chamber
22、. The calibration coefficients are used internally during measurements to calibrate the signals from the sensors. The accuracies for T and RH are 0.5 C (at 25 C) and 3.5% respectively.The Intersema MS5534B is a SMD-hybrid device that includes a piezoresistive pressure sensor and an ADC-Interface IC.
23、 It provides a 16 bit data word from a pressure and T (40 to +125C) dependent voltage. Additionally the module contains six readable coefficients for a highly accurate software calibration of the sensor.The TSL2550 is a digital-output light sensor with a two-wire, SMBus serial interface. It combines
24、 two photodiodes and an analog-to digital converter (ADC) on a single CMOS integrated circuit to provide light measurements over a 12-bit dynamic range. The ADXL202E measures accelerations with a full-scale range of 2 g. The ADXL202E can measure both dynamic acceleration (e.g., vibration) and static
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- zigbee 检测 探头 冷藏 蔬菜 运输 现实 条件下 测试
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