超高台阶排土场建设决策研究与实践

 建设超高台阶排土场是减少国土矿业破坏的重大举措,基底承载、稳态分析、泥石流、土场水患是建设决策关键。创新研究建成了厂坝七架沟400 m高台阶大型排土场,发展了高台阶土场基底承载机制与土场极限堆高确定技术、相应稳态分析技术、控制微粒细粒料源的土场泥石流扼制技术,建成了我国第一个土场底部泄流体。成功实践后又在南芬庙儿沟超大型土场应用与深化,收效卓著。可供借鉴。     

基于DSP的回声抵消器的设计与实现

在会议电视、免提电话等易出现回声的通信系统中 ,回声抵消器是一个必不可少的设备 它的基本原理是用一个自适应滤波器来辨识并模拟回声路径以实现回声对消 ,而数字信号处理器的快速发展也使自适应滤波器实时、经济地实现成为可能 本文以TMS32 0C5 4X为例 ,对在DSP上实现声回声抵消算法所需要的相关技术做了研究和探讨 ,并提出了一种基于PNLMS和块更新算法的新的自适应方案     

综合底层、语义特征和相关反馈的医学图像检索

医学图像数据库的不断庞大使得医学图像检索成为研究热点。文章根据胸片图像的特点,提出了一种结合图像纹理、形状和语义信息的胸片图像检索方法。同时,还将相关反馈技术融合到算法中。据此,实现了一个图像检索原型系统,依据所设计的评价实验,将不同实验的检索结果进行了比较和分析。实验证明,该文提出的方法具有良好的检索效果。     

越南河内还剑湖历史地区的保护与再开发——趋向场所精神的保护

本论文建议通过保护世界历史与自然遗产,再生场所的记忆和复兴经济活力来保护还剑湖历史地区的内在精神,提出将现有建成的历史环境分成不同层次－－这些层次体现了残民地和后殖民地时期的设计理念和经济政治条件,然后通过设计导则对其进行保护。在这些设计导则的基础上,提出了还剑湖历史地区的整体保护规划。     

Medical image compression by discrete cosine transform spectralsimilarity strategy

Due to bandwidth and storage limitations, medical images must be compressed before transmission and storage. However, the compression reduces the image fidelity, especially when the images are compressed at low bit rates. The reconstructed images suffer from blocking artifacts and the image quality is severely degraded under high compression ratios. In this paper, we present a strategy to increase the compression ratio with low computational burden and excellent decoded quality. We regard the discrete cosine transform as a bandpass filter to decompose a sub-block into equal-sized bands. After a band-gathering operation, a high similarity property among the bands is found. By utilizing the similarity property, the bit rate of compression can be greatly reduced. Meanwhile, the characteristics of the original image are not sacrificed. Thus, it can avoid the misdiagnosis of diseases. Simulations were carried out on different kinds of medical images to demonstrate that the proposed method achieves better performance when compared to other existing transform coding schemes, such as JPEG, in terms of bit rate and quality. For the case of angiogram images, the peak signal-to-noise-ratio gain is 13.5 dB at the same bit rate of 0.15 bits per pixel when compared to the JPEG compression. As for the other kinds of medical images, their benefits are not so obvious as for angiogram images; however, the gains for them are still 4-8 dB at high compression ratios. Two doctors were invited to verify the decoded image quality; the diagnoses of all the test images were correct when the compression ratios were below 20     

Effect of electrical discharge machining on the characteristics of carbon fiber reinforced carbon composites

This work investigated electrical discharge machining (EDM) of carbon fiber reinforced carbon composite material. The characteristics of composites machined by EDM were studied in terms of machining parameters. An empirical model of the composites was also proposed based on the experimental data. The composite material was produced by an electrical discharge sinker using a graphite electrode. The workpiece surface and resolidified layers were examined by scanning electron microscopy (SEM). Moreover, surface roughness was determined with a surface profilometer. Experimental results indicate that the extent of delamination, thickness of the recast layer, and surface roughness are proportional to the power input. The EDM process effectively produces excellent surface characteristics and high quality holes in composites under low discharge energy conditions.     

Hybrid model- and signal-based chatter detection in the milling process

Chatter causes machining instability and reduces productivity in the metal cutting process. It has negative effects on the surface finish, dimensional accuracy, tool life and machine life. Chatter identification is therefore necessary to control, prevent, or eliminate chatter and to determine the stable machining condition. Previous studies of chatter detection used either model-based or signal-based methods, and each of them has its drawback. Model-based methods use cutting dynamics to develop stability lobe diagram to predict the occurrence of chatter, but the off-line stability estimation couldn’t detect chatter in real time. Signal-based methods apply mostly Fourier analysis to the cutting or vibration signals to identify chatter, but they are heuristic methods and do not consider the cutting dynamics. In this study, the model-based and signal-based chatter detection methods were thoroughly investigated. As a result, a hybrid model- and signal-based chatter detection method was proposed. By analyzing the residual between the force measurement and the output of the cutting force model, milling chatter could be detected and identified efficiently during the milling process.

     

HFC网络MAC协议的三叉树冲突化解算法分析

对HFC网络中普遍采用的三叉树冲突化解算法进行分析，介绍树冲突化解算法的两种栈管理模式：FIFO(先进先出)模式和LIFO(后进先出)模式，并举例说明FIFO和LIFPO的冲突化解过程。     

Effect of CuO Addition on Microwave Dielectric Properties of 0.80Sm(Mg0.5Ti0.5)O3-0.20Ca0.8Sr0.2TiO3 Ceramics

The effects of CuO addition on phase composition, microstructure, sintering behavior, and microwave dielectric properties of 0.80Sm(Mg_0.5Ti_0.5)O₃-0.20 Ca_0.8Sr_0.2TiO₃(8SMT-2CST) ceramics prepared by a conventional solid-state ceramic route have been studied. CuO addition shows no obvious influence on the phase of the 8SMT-2CST ceramics and all the samples exhibit pure perovskite structure. Appropriate CuO addition can effectively promote sintering and grain growth, and consequently improve the dielectric properties of the ceramics. The sintering temperature of the ceramics decreases by 50°C by adding 1.00 wt.%CuO. Superior microwave dielectric properties with a ε _r of 29.8, Q × f of 85,500 GHz, and τ _f of 2.4 ppm/°C are obtained for 1.00 wt.%CuO doped 8SMT-2CST ceramics sintered at 1500°C, which shows dense and uniform microstructure as well as well-developed grain growth.     

在非晶硅上制备角度可控缓坡的方法

介绍了一种利用光的衍射原理制备角度可控缓坡微结构的方法。该方法在光刻步骤中通过调节掩膜板与基片之间的垂直距离来控制光刻胶图形边缘曝光量,光刻显影后得到剖面为正梯形的光刻胶图形,再经过干法刻蚀得到非晶硅的缓坡微结构。结果表明,制备的非晶硅缓坡结构角度（可小于30°）可控,制备方法简单,与半导体工艺兼容,可避免湿法刻蚀带来的过蚀及角度不均匀问题。