水果品质近红外检测技术的研究现状与发展

简单概述了我国水果产业的发展现状,着重阐述了国内外利用近红外光谱技术进行水果品质无损检测的最新研究成果,分析了当今研究中存在的问题,提出了利用近红外光谱技术进行水果检测的发展方向。     

Crystallographic Orientation Identification in Multicrystalline Silicon Wafers Using NIR Transmission Intensity

Near-infrared (NIR) polariscopy is a technique used for the non-destructive evaluation of the in-plane stresses in photovoltaic silicon wafers. Accurate evaluation of these stresses requires correct identification of the stress-optic coefficient, a material property which relates photoelastic parameters to physical stresses. The material stress-optic coefficient of silicon varies with crystallographic orientation. This variation poses a unique problem when measuring stresses in multicrystalline silicon (mc-Si) wafers. This paper concludes that the crystallographic orientation of silicon can be estimated by measuring the transmission of NIR light through the material. The transmission of NIR light through monocrystalline wafers of known orientation were compared with the transmission of NIR light through various grains in mc-Si wafers. X-ray diffraction was then used to verify the relationship by obtaining the crystallographic orientations of these assorted mc-Si grains. Variation of transmission intensity for different crystallographic orientations is further explained by using planar atomic density. The relationship between transmission intensity and planar atomic density appears to be linear.     

基于可见光及近红外的仿生视觉成像技术

为了解决传统单通道仿生视觉成像系统应用场景受限的问题,提出一种基于可见光及近红外的仿生视觉成像技术.首先,对多光谱光学成像系统进行研究,设计了以棱镜为分光元件的同口径双通道成像系统,对目标物体进行初步成像.然后,利用基于Roberts算子的图像清晰度评价函数并结合自适应变步长搜索策略对目标物体进行清晰成像.最后,搭建了以液体变焦透镜为调焦执行机构的实验装置,验证仿生视觉成像系统及自动调焦算法的实际性能,实验结果表明:光学系统的成像质量可满足实际需求,同时,自动调焦算法完成一次调焦过程的时间仅为1050 ms.     

Selection of the Temperature in the Sugar Content Determination of Kiwi Fruit

In the last few years, the production of kiwifruit (Actinidia deliciosa) has undergone a significant development with increasing international market. Therefore, the use of fast and non-destructive methods for ripening control is desirable. In this sense, NIRS technology (Near Infrared Spectroscopy) has proved to be very useful. The objectives of this work were to estimate the soluble solids content from NIRS technology and to evaluate the influence of the kiwifruit temperature on the NIR measures. A sample of 210 fruits was collected and stored for three months under cold conditions. The NIR measures were done at three kiwifruit temperatures (0.5°C, 10°C and 20°C) and the refractometric index was determined at the end of the experiment. The reflectance spectra in the near-infrared region between 800 and 2500 nm were measured with a Varian CARY 500 spectrophotometer equipped with an integrated sphere to measure reflectance in solid samples. The information has been analysed with Unscramble and SPSS statistical programs, which include a wide range of rapid data-processing applications and procedures, with a large number of options and graphic representations. The test performed for this study are PLS (partial least squares regression) and DA (discriminate analysis). Results showed: the validity of this technology to obtain a relationship between the NIRS and the soluble solids content, and differences on the wavelengths used in the calibrations, depending on the kiwifruit temperature.     

Transabdominal Fetal Heart Rate Detection Using NIR Photopleythysmography: Instrumentation and Clinical Results

In obstetrics, fetal heart rate (FHR) detection remains the standard for intrapartum assessment of fetal well-being. In this paper, a low-power (<55 mW) optical technique is proposed for transabdominal FHR detection using near-infrared photoplesthysmography (PPG). A beam of IR-LED (890 nm) propagates through to the maternal abdomen and fetal tissues, resulting in a mixed signal detected by a low-noise detector situated at a distance of 4 cm. Low-noise amplification and 24-bit analog-to-digital converter resolution ensure minimum effect of quantization noise. After synchronous detection, the mixed signal is processed by an adaptive filter to extract the fetal signal, whereas the PPG from the mother's index finger is the reference input. A total of 24 datasets were acquired from six subjects at 37 plusmn 2 gestational weeks. Results show a correlation coefficient of 0.96 (p-value < 0.001) between the proposed optical and ultrasound FHR, with a maximum error of 4%. Assessment of the effect of probe position on detection accuracy indicates that the probe should be close to fetal tissues, but not necessarily restricted to head or buttocks.     

近红外漫反射光谱在人体血糖无创检测中的应用

采用近红外漫反射光谱技术对人体血糖进行了无创检测。实验使用Nexus - 870傅立 叶红外光谱仪及其光纤附件,采集了6名不同年龄健康志愿受试者手腕处的近红外漫反射光谱。对光谱进行了平滑、基线校正和二次求导预处理,采用偏最小二乘( PLS)方法在含有葡萄糖吸收峰的7500～8500cm- 1波段建立同一个体、相同年龄段的不同个体、以及不同年龄段的不同个体的校正模型。采集漫反射光谱的同时抽适量的血样在752型紫外光栅分光光度计上标定血糖的实际值,并对校正模型计算值和实际标定值进行了比较,结果表明个体建模的相关性很好,相关系数达到0. 99980,均方差在≤0. 346,误差分布在±0. 8mmol/ l之间。对部分不参与建模的样品进行了预测,结果表明个体建模的自我预测结果好于该模型对其它个体样品的预测结果,预测误差≤0. 89544mmol/ l。     

MPLS技术以及在网络中的应用

详细论述了目前网络发展的新趋势，多协议标记交换（MPLS）技术的具体组成和图示表示，并且说明了MPLS在网络中的具体应用。     

单片机应用系统抗干扰技术

本文从硬、软件两方面阐述了单片机应用系统抗干扰技术,这些技术在实际应用中取得了良好的效果.     

变流器的PWM整流技术

PWM整流技术是一种复杂可控整流技术,具有多种优点。在对三相正弦系统进行矢量分析的基础上,本文探讨PWM整流器的控制策略,并简要介绍产品试验的运行情况。     

光纤码分多址技术在城域接入网中的应用

分析了光纤码分多址技术O -CDMA在城域接入网中的应用。回顾了O -CDMA技术的发展历史 ,详细地介绍了O -CDMA技术的特点 ,其具有的公平性、灵活性、网络控制管理、对服务区处理能力以及高的安全性使O -CDMA技术成为较好的城域接入网技术。阐述了目前在应用中O -CDMA存在的一些技术方面的问题     

智能电网应用的大功率IGBT模块技术

近年来IGBT模块技术进步扩展了IGBT应用范围,进入了诸如轨道牵引、HDVC和包括智能电网系统的电能质量等真正的大功率领域。本文着重IGBT技术及其在欧盟UNIFLEX-PM（未来电网通用灵活电能管理先进功率变流器）项目应用情况。     

用微波技术测定黄豆粒的含水率

矩形谐振腔工作于ＴＥ１０７模式（中防频率５．８０ＧＨｚ）。黄豆粒置于腔中心,通过测量由它引起的谐振频率偏移和腔传输特性的变化,就可以确定黄豆粒的湿度,其不确定性小于１％,可信度达９５％。     

利用LIGA技术制造夹钳

在航天、国防、医学、核物理等领域,有着对仪器设备向小型化、复杂化、集成化方向发展的要求。在这一动力驱动下,精密机械加工、 Ｌ Ｉ Ｇ Ａ 技术以及硅技术有了长足发展,制造出许多部件和产品。但对于复杂的微机电系统,单靠这些技术难以实现,需要进行系统的装配工作。微夹钳也是在这一需求下发展起来的。除此之外,在细胞操作和其他微细操作过程中也迫切需要这样的执行软件。本文利用 Ｌ Ｉ Ｇ Ａ 技术进行了这方面的研究工作,并得到了一些结果。     

采用双扫描平台技术的ArF浸液式光刻

在193nm光刻中,已证明水是一种适于浸液式光刻的液体。浸液式光刻提出了一种可将传统的光学光刻拓展到45nm节点,甚至到32nm节点的潜能。另外,利用现有的透镜,浸液式光刻的选择提出了根据实际的数值孔径和特征图形可增大50%及更大的焦深范围。讨论了采用浸液式光刻获得的成像结果和套刻结果。采用一个0.75数值孔径的ArF透镜,我们用双扫描平台技术(TWINSCANTM)组装一台浸液式扫描光刻机的原理型样机。最初的浸液式曝光实验数据证明了焦深的增加较大,同时以高扫描速度保持了图像的对比度。在初期引入的生产型浸液式光刻中,将采用一个0.85数值孔径的ArF透镜。该系统的分辨率将以大于0.5μm的焦深有效地支持65nm节点半导体器件的加工。这种系统初始的成像技术数据证实有效的增大了其焦深范围。     

应用iBeacon的O2O解决方案

分析基于服务类电商的O2O模式兴起的原因及应用场景,对i Beacon等周边互联技术进行研究,介绍i Beacon技术的应用商业场景和局限性,最后对未来基于服务类电子商务的新商业模式进行了展望。     

基于LTCC技术的均衡器设计

均衡器作为微波系统的重要组成部件,其特性直接影响系统的性能。应用ADS仿真软件,将2种常规形式的均衡器进行整合,建立了电路仿真模型并进行元件值的仿真;基于低温共烧陶瓷(LTCC)介质基板的三维布线能力模拟对应的电感和电容元件,将平面结构转化为三维立体结构,并在高频结构仿真软件(HFSS)中进行整体建模,优化设计,最后得到一款工作于950～2150MHz的均衡器。测试结果表明均衡量5 dB,回波损耗≤-20 dB,实现了小型化和高可靠性。     

In Vivo Imaging of Composite Hydrogel Scaffold Degradation Using CEST MRI and Two‐Color NIR Imaging

Hydrogel scaffolding of stem cells is a promising strategy to overcome initial cell loss and manipulate cell function post‐transplantation. Matrix degradation is a requirement for downstream cell differentiation and functional tissue integration, which determines therapeutic outcome. Therefore, monitoring of hydrogel degradation is essential for scaffolded cell replacement therapies. It is shown here that chemical exchange saturation transfer magnetic resonance imaging (CEST MRI) can be used as a label‐free imaging platform for monitoring the degradation of crosslinked hydrogels containing gelatin (Gel) and hyaluronic acid (HA), of which the stiffness can be fine‐tuned by varying the ratio of the Gel:HA. By labeling Gel and HA with two different near‐infrared (NIR) dyes having distinct emission frequencies, it is shown here that the HA signal remains stable for 42 days, while the Gel signal gradually decreases to <25% of its initial value at this time point. Both imaging modalities are in excellent agreement for both the time course and relative value of CEST MRI and NIR signals (R² = 0.94). These findings support the further use of CEST MRI for monitoring biodegradation and optimizing of gelatin‐containing hydrogels in a label‐free manner.     

基于研磨抛光切片技术的芯片结构观察研究

芯片结构观察广泛应用于芯片的生产、工艺改进、失效分析和可靠性等领域。芯片结构分为剖面结构和表面各层结构,对芯片进行切片是观察其内部结构的一种较为简便的方法。研磨抛光切片是一项低成本的切片技术,但由于精度较低、操作复杂,较少应用于芯片的结构观察。详细说明了研磨抛光切片技术的原理,给出了改进后的切片工艺,并通过实例说明该方法在芯片剖面结构观察和表面各层结构观察中的应用。该方法可满足大部分情况下对芯片结构观察的需要。讨论了该技术目前存在的问题。     

一种波长可调的近红外波段完美吸收体

一般将电磁波完美吸收体简称为完美吸收体,它可用于很多行业。用有限时域差分法研究了一种可以在近红外波段工作的完美吸收体。模拟结果表明,这种完美吸收体可以实现98%的单峰1400 nm左右宽谱吸收,或者可以实现90%以上的1320 nm和1640 nm波长的双峰吸收效率。通过调节共振腔结构的大小可以调节吸收波长和吸收宽度。电磁波完美吸收体是一种背靠背双共振腔模式的完美吸收体,有非常广泛的应用前景。     

使用移动Agent技术的网络管理

当今大型的通信网络往往集成了来自多家厂商的网络和通讯设备，而基于集中式方式的传统网络管理已难以满足用户的需求。移动ａｇｅｎｔ是能够自动在网络各节点间移动并代表其它实体工作的软件实体，引起了人们广泛关注。文章介绍了有关移动ａｇｅｎｔ的基本概念及其系统实现，并讨论了网络管理中移动ａｇｅｎｔ技术的几个应用实例以表明移动ａｇｅｎｔ是解决异构环境的复杂网管的有效途径。