快速覆盖式分形压缩算法

提出了一种覆盖式分形压缩方法,并给出了相应快速搜索算法.该方法采用四连通扩充的方式,在给定误 差范围内,尽可能地合并规则Range分区,从而减少所需迭代变换的数目.为减少存储Range分区信息所需的字 节,在存储压缩映射时,根据Range分区多边形的边数调整存储顺序,对于那些复杂的Range分区,只记录其外接 矩形框信息.在解码时,采用一种覆盖式绘制方法,可以完全恢复原Range分区情形.通过对Lenna,图象的实验表 明,在恢复图象的信噪比为29.63dB时,可以达到41倍的压缩倍数.     

秦腔术语翻译初探

秦腔是中国戏曲百花园中的一枝奇葩,已被列入中国非物质文化遗产.目前,对秦腔的研究只是停留在剧本的创作和保护与振兴工作方面,很少有学者进行专门的秦腔翻译工作.其实,秦腔的翻译对于秦腔打开门户,走向世界这一广阔的市场具有重要的现实意义.本文参考目前京剧的翻译,对秦腔的术语进行了试译,对今后秦腔的翻译和推介工作有较强的借鉴作用,对于其他剧种的术语翻译也具有一定的参考价值.     

面向沟通型工程师的机械工程专业英语教学实践

本文从大学生在进入机械工程专业英语学习阶段前的基础英语水平现状和需求分析出发,结合未来作为-名沟通型工程师的时代需要,对机械工程英语课程内容设置、教学方法等方面进行了相关的探索与实践,旨在为专业英语的教学改革提供有益的借鉴.     

饱水石灰岩骨架和流体弹性参数的估算

本文利用Niu等提出的基于临界孔隙度模型的组分弹性参数数值计算方法,把测试岩石样品的孔隙度、整体密度、纵波速度和横波速度作为数值计算的输入数据,运用双线性数值计算方法反演求出临界点、流体和骨架的12个弹性参数。具体做法是:基于临界孔隙度模型,给出三组线性关系,即密度—孔隙度,整体剪切模量—孔隙度,整体纵波模量—孔隙度,上述每组线性关系分别以孔隙度作为自变量和因变量得到两个线性方程,再把两个方程计算的结果进行加权平均得到相关的弹性参数估算值,并结合饱水石灰岩样品数据实现了弹性参数估算。数值计算结果表明,由数值计算得到的弹性参数与测试弹性参数的均值和方差相差甚微,特别是密度数据的偏差均值更小,说明文中的数值计算结果是可靠的。     

Power-efficient M-ary PSSK Communications with Uncertain Phase Errors

M-ary phase-silence-shift-keying (PSSK), one of power-efficient modulation schemes, has enhanced symbol error rate (SER) performance by 6 dB compared with that of the conventional phase-shift-keying (PSK). Phase tracking problem of the PSSK with phase-locked-loop (PLL) is discussed in this paper. Capacity of the PSSK for the additive white Gaussian noise (AWGN) channel and Rayleigh fading channel is analyzed. Capacity loss of the PSSK due to the PLL is small, which tells us that the PSSK demodulator can be practically implemented.     

德国ZWICK/ROELL 4106E熔融指数仪的使用与维护

本文对德国ZWICK/ROELL公司生产的4106E熔融指数仪的测试要求进行了简单介绍,并针对该仪器在使用与维修中出现的技术问题进行了分析和探讨,提出了相应的解决措施。     

6m焦炉推焦机的结构特点及优化设计

介绍了6 m焦炉推焦机的结构特点。通过规范主动齿轮与齿条的啮合、规范走行轨道和推焦杆支辊的标高、调节滑履高度和在推焦杆两侧加装耐热材料可以解决推焦杆振动和推焦杆中前部立板产生裂纹的问题。     

Infrared emission properties and energy transfer in ZnO-SiO2:Yb composites

Intense near-infrared emission at 1 μm has been obtained in ZnO-SiO₂:Yb³⁺ composites via a facile sol-gel method upon broadband ultraviolet light excitation. Systematic optical measurements including static and time-resolved photoluminescence have been performed to elucidate the energy transfer from ZnO quantum dots to Yb³⁺ ions. The dependence of energy transfer efficiency on Yb³⁺ concentration has been investigated in detail. Codoping with Li⁺ ions leads to about twice enhancement of the near-infrared luminescence intensity around 1 μm at room temperature. The enhancement in the luminescence intensity could be mostly attributed to the modification of the local symmetry around Yb³⁺ ions by codoping with Li⁺ ions.     

In situ continuously monitoring the early age microstructure evolution of cementitious materials using ultrasonic measurement

The early age microstructure evolution was continuously monitored by using a specially improved ultrasonic monitoring apparatus. The influence of water-to-binder ratios, mineral admixtures, aggregates and temperature were systematically investigated. The experimental results show that concrete can be clearly classified into four stages, while only the three stages can be observed without coarse aggregates. In addition, pre-percolation threshold, percolation threshold and full connectivity of the solid phase were identified. The microstructure formation is promoted with the reduced water-to-binder ratios, increased temperature, silica fume and aggregates addition, while the reverse phenomenon is observed when fly ash and slag are incorporated.