公共图书馆数字阅读服务实践与研究

数字阅读服务是图书馆适应数字时代发展的产物,是数字资源与阅读服务的结合。分析了东莞图书馆数字阅读服务工作基本现状及创新亮点,阐述了东莞图书馆数字阅读的服务效果,对公共图书馆如何做好数字阅读服务工作进行了思考。     

现代图书馆的服务原则与服务内容

在读者需求、读者行为、出版模式、信息技术、社会期望等一系列变化的环境下,图书馆服务呈现新的发展趋向。现代图书馆的服务原则除基本保障原则外,还有开放与共享、公平与平等、公益与免费、便利与高效、多样与满意、创新与发展。服务内容有文献服务、信息服务、知识服务、方法服务、文化服务、空间服务、智能服务、移动服务。     

Green Determination of Total Iron in Water by Digital Image Colorimetry

A green iOS digital image colorimeter was fabricated for the determination of total iron in natural water. A mobile application operating on an iOS device was designed using Euclidean distance theory to perform iron determination. The application records the components of the color by storing red, green, and blue values as well as calculating the hue, saturation, brightness, and gray values using standard color theory. The component values obtained from the images of orange solutions of iron(II) complex with 1,10-phenanthroline were collected in a database and used for evaluation of the total iron concentration in water samples. Under the optimal conditions for solid-phase extraction used for sample preconcentration, the enrichment factor was 8.18. The iron concentration was determined by this device for concentrations from 0.01 to 1.0?ppm. The iOS digital image colorimeter achieved a limit of quantitation of 0.1?ppm. The accuracy and precision of the iOS digital image colorimeter were validated using a certified reference material, riverine water. The instrumentation was used for the analysis of natural water samples.     

Experimental characterization of dynamic behaviour of gelatin-based material using DIC

In this paper, the dynamic response of gelatin-based soft material under impact loading is investigated. The dynamic tests are principally performed by the classical SHPB (Split Hopkinson Pressure Bars) technique. However, due to the very low mechanical impedance of the specimen compared with the Hopkinson bars, the feeble impact forces are measured by highly sensitive piezoelectric polyvinylidene fluoride (PVDF) pressure sensors instead of SHPB measurement system. The PVDF pressure sensors are placed on the interfaces between the specimen and the bars. During the impact test, the non-equilibrium stress state and inhomogeneous strain fields are developed in the specimen; a digital image correlation (DIC) technique is proposed to identify the inhomogeneous displacement fields using high speed photography. A non-parametric approach based on the DIC technique is developed to deduce the transient stress fields in the longitudinal and transverse directions from the displacement fields measured by DIC. The validation of the calculated stress fields is performed by comparing them with the stress measurements from the PVDF pressure sensor at the bottom end of the specimen. Furthermore, stress-strain response is carried out using this approach throughout the specimen. It is clearly shown that the average highest strain rate varies with position in the specimen. This lead to multiple stress-strain relations determined at different strain rates by only one impact test. The significant strain rate sensitivity is observed at the tested rate range from 81/s to 269/s. Under compression loading, the axial stress state is developed as a simple compression only in the central part of the specimen due to the friction at the interfaces between the specimen and the bars. According to the calculated results based on movement of “long waves”, the region of the simple compression stress state in the central part of the specimen is localized. It is observed that the axial stress is much more important than the transverse stress in the central part and this confirms the assumption of uni-axial compression stress state in the specimen.     

中波红外景象投影光学系统消热差设计

针对红外成像系统性能测试与评估的应用需求,设计了一套基于数字微镜器件的消热差的中波红外景象投影光学系统.探讨了红外视景仿真用投影光学系统的像差特性和设计方法,并对投影系统的无热化进行了分析.采用分光板和补偿板方案,解决了大相对孔径条件下投影系统的远心照明分光和像差平衡问题,提高了分辨率和均匀性,增大了视场.系统由远心投...     

一种在二步相移数字全息中实现准确相移的方法

相移数字全息中的相移准确性决定了重建结果的质量,本文提出了在二步相移数字全息中.实现准确相移的方法.该方法使用数字电压源开环控制普通的压电陶瓷微位移器,通过连续以微小的间隔来改变施加在压电陶瓷微位移器上的电压,可以获得一系列对应于不同相移角的全息图像,进而可以利用这些全息图像重建出来物光波在全息面上的强度分布.实验中采...     

无人机光电载荷图像处理器的设计

介绍了无人机载设备的技术特点及机载小型图像处理器的组成。采用TI公司的数字信号处理器芯片为核心处理器,配合现场可编程逻辑器件(FPGA)与外部管理微控制单元(MCU)来实现目标数据的采集与处理,设计了适用于无人机光电载荷的超小型图像处理器系统。针对机载设备的特点,设计时充分考虑了体积、重量、功耗等要求。该系统已应用于多台套机载光电载荷中,工作稳定可靠,满足无人侦察机对捕捉和定位目标的要求。     

Examination of the upper measurement limit in displacement measurement using fringe compensation in digital holography

Digital holography is a widely used method for displacement measurement in coherent optical metrology. An obvious limit of the method is that too large displacements result in dense fringes, so the fringes are practically invisible. The maximum number of contour fringes in displacement measurement is limited, because the cameras are discrete devices and sampling theory plays an important role. Because of the limited measurement range, compensation methods are promising tools for practical measurements. It can be shown that the practical measurement range can be extended above the Nyquist sampling limit. Compensation methods can be digital, because digital holographic interferometry operates with images recorded with a digital camera. In our research work the upper measurement range of fringe compensation method was examined. Our goal was to perform automatic compensation even if the displacement is higher than the measurement range of the basic method. The operation of the automatic fringe compensation method was based on the combination of two types of out-of-plane displacement measurements with different sensitivities.     

Real-time optical reconstruction of the diffused 3D object using phase information calculated by Continuous Wavelet Transform

We propose the real time optical reconstruction of a three-dimensional (3D) object from a digitally recorded hologram. Phase distribution of the recorded hologram is numerically calculated by 1-dimensional Continuous Wavelet Transform (1D-CWT) for digital reconstruction with phase only information. Also, the phase distribution of 1D-CWT transferred to the spatial light modulator (SLM) is used to obtain optically reconstructed image. It is observed that an efficient real-time analysis can be achieved, if phase of 1D-CWT is used. In the same time, optically reconstructed 3D objects obtained by only phase information are about three times brighter than bleached hologram intensity's. So the minimum power loss can be obtained. Numerical and experimental results are presented.