基于ARM核的发射机控制器设计

ARM体系微处理器由于比单片机具有更高的性能,在工业控制领域中的使用日益广泛,文章选用了44B0x处理器作为控制器内核,开发完成了约定键盘、菜单操作及LCD显示程序数据采集及处理实现软件PC通信协议及实现软件,在其控制下完成数据地采集处理并实现对广播发射机的工作状态进行监控,同时还具有人机交互和数据管理的功能。     

一种新的指纹图像复合分割方法

本文在分析了方差法,方向图法和角部灰度均值法的优缺点后,将它们合理的结合,提出了一种新的基于方向图和角部灰度均值的复合分割方法。本算法的优点是充分利用了指纹图像特有的方向性和灰度特性,对于方向图法和方差方法单独应用时无效的情况都适用,能准确地将背景区域从指纹图像中分离出来,从而提高了分割的精确度。     

PhotoShop在网页图像处理中的应用

图像是网页中重要的要素之一,关系到网页的整体视觉效果,影响着网页的打开速度.对网页中图像元素的处理是网页制作中的重要环节.PhotoShop是一款优秀的图像处理工具,广泛应用于图像处理与合成等设计领域,在对网页图像处理方面也表现出独特的优势.根据实践,阐述利用PhotoShop对网页图像格式处理、GIF透明背景、全景合成、批处理图片的应用技巧.     

某铜矿露天转地下隔离矿柱的确定研究

露天转地下隔离矿柱的确定是露天转地下开采经常面临的重要问题,对于金属矿山地下安全生产极其重要。根据某铜矿的采矿工艺、开采深度以及工程地质条件,采用理论计算和FLAC3D有限差分法数值软件对不同厚度的隔离矿柱进行了模拟分析。结果表明,当隔离矿柱厚度为 20 m时,地下开挖导致的顶板变形较小且趋于平稳。20 m是该矿山隔离矿柱厚度的最优值,能够满足安全生产要求。该分析结果为露天转地下安全高效回采提供了理论依据和技术指导。     

气相色谱-质谱联用法研究硅橡胶中甲基环硅氧烷向食品模拟液的迁移

目的探究市售硅橡胶蒸篦中的甲基环硅氧烷类有毒物质的迁出规律,对食品接触硅橡胶材料使用安全性进行评价。方法将市售硅橡胶蒸篦在实际使用温度(100℃热空气)下进行老化,并用不同食品模拟液(水、4%乙酸(V:V)、正己烷)对其进行处理,利用气质联用(GC-MS)分析仪对其中甲基环硅氧烷类有毒物质的迁出量进行检测。结果以正己烷为模拟液时,硅橡胶中分子量较低的甲基环硅氧烷在4 h时已全部迁出至模拟液中,而以超纯水和4%乙酸为模拟液时,没有有机小分子的迁出。结论食品接触硅橡胶材料在中性和酸性条件下使用安全,但在油性环境下使用会存在安全隐患。     

Comparison of Direct and Indirect Boundary Shear Stress Measurements along Vegetated Streambanks

Estimates of boundary shear stress along vegetated streambanks are needed to predict streambank fluvial erosion. Because fluvial shear stress cannot be directly measured in the field, reliable estimation techniques using field instrumentation are needed. This study evaluated local bank shear stress estimation methods applicable to sloping, vegetated streambanks. Two reaches of a second order stream were modelled in a flume using a fixed‐bed Froude‐scale modelling technique. One reach was dominated by dense shrubs while the other reach was located in a mature forest. Direct measurements of local bank shear stress using a hot‐film anemometer were compared to estimates based on velocity measurements (logarithmic method, Reynolds stresses, and turbulent kinetic energy). For channels with no or widely spaced vegetation, the velocity‐based estimates underestimated the bank shear stress due to secondary flow contributions. For banks with dense vegetation, Reynolds stresses and turbulent kinetic energy estimates were statistically similar to direct measurements on average, but substantial error occurred when making point comparisons. Velocity‐based estimates generally over predicted bank stress in areas of high shear at the vegetation edge and underpredicted stress within dense vegetation. Ultimately, results suggest that none of tested techniques can be broadly applied to streambanks, and flow structure is critical in selecting the appropriate estimation technique. Copyright © 2016 John Wiley & Sons, Ltd.     

Maximising performance of optical coherence tomography systems using a multi-section chirped quantum dot superluminescent diode

Key device requirements for maximising resolution in an optical coherence tomography system are discussed. The design and operating parameters of a multi-contact quantum dot superluminescent diode incorporating a number of features which inhibit lasing are described. Such devices allow the independent tuning of emission power and spectral shape; hence the penetration depth and resolution in optical coherence tomography are decoupled. The emission spectrum of a device utilising chirped quantum dots is shown to be tuned to produce a broadband single Gaussian emission, centred at the required wavelength of 1050 nm, with high output powers than a single contact device.     

1.3 /spl mu/m InAs/GaAs multilayer quantum-dot laser with extremely low room-temperature threshold current density

A high growth temperature step used for the GaAs spacer layer is shown to significantly improve the performance of 1.3 /spl mu/m multilayer InAs/GaAs quantum-dot lasers. Extremely low room-temperature continuous-wave threshold current densities of 32.5 and 17 A/cm/sup 2/ are achieved for a three-layer device with as-cleaved facets and high-reflectivity coated facets, respectively.     

一种14位、1.4MS/s、多位量化的级联型Σ△调制器

在 0 .6μm CMOS工艺条件下设计了一种适合 DECT(Digital Enhanced Cordless Telephone)标准的 1 .4MS/s Nyquist转换速率、1 4位分辨率模数转换器的ΣΔ调制器。该调制器采用了多位量化的级联型 (2 -1 -1 4b)结构 ,通过 Cadence Spectre S仿真验证 ,在采样时钟为 2 5 MHz和过采样率为 1 6的条件下 ,该调制器可以达到 86.7d B的动态范围 ,在 3 .3 V电源电压下其总功耗为 76m W。