区域似大地水准面精化中几个问题的探讨

精确确定高精度、高分辨率似大地水准面,是建立现代大地测量基准和地理空间基础框架的 基础性工作。全球定位系统（GPS）技术结合高精度、高分辨率的区域似大地水准面模型,可以取代 传统的低等级水准测量,真正实现GPS定位技术的三维定位功能。基于此,文中就高精度区域似 大地水准面精化应注意的一些问题进行了探讨,以供有关单位在精化区域似大地水准面时参考。     

微细超声波加工工具损耗机理的实验研究

针对微细超声波加工中工具损耗严重的问题,分析了其中可能造成工具快速损耗的原因。这些原因主要有工具和工件的直接撞击作用、磨粒的撞击作用、磨粒的切削和刮擦作用、超声空化作用及化学腐蚀作用。通过设计加工实验,用单一因素控制法对这些原因的影响效果进行分析,最后得出磨粒的高频撞击作用是造成微细超声波加工中工具损耗的主要原因。     

DNA-wrapped carbon nanotubes as sensitive electrochemical labels in controlled-assembly-mediated signal transduction for the detection of sequence-specific DNA

A novel electrochemical strategy that uses DNA-wrapped carbon nanotubes (CNTs) as electrochemical labels is developed for sensitive and selective detection of sequence-specific DNA. The presence of target DNA mediates the formation of a sandwiched complex between the DNA-wrapped CNT and a hairpin DNA capture probe immobilized on magnetic beads. This allows target-selective collection of the CNT labels by magnetic separation and transfer on the electrode surface modified with an insulating self-assembled monolayer (SAM). After treatment with N,N-dimethylformamide, the collected sandwiched complex releases the bare CNTs and facilitates the removal of magnetic beads from the electrode surface. The bare CNTs can then assemble on the SAM-modified electrode surface and mediate efficient electron transfer between the electrode and the electroactive species in the solution with a strong current signal generated. The results indicate that the developed strategy shows a sensitive response to target DNA with a desirable signal gain and a low detection limit of 0.9 pM. This strategy is also demonstrated to provide excellent differentiation of single-base mismatch in target DNA. It is expected that this electrochemical strategy may hold great potential as a novel platform for clinical diagnostics and genetic analysis.     

ReliefF-SVM RFE组合式特征选择人脸识别

针对人脸识别中因特征个数较多对识别的实时性和准确性影响较大的问题,提出了ReliefF-SVM RFE组合式特征选择的人脸识别方法。利用离散余弦变换提取特征和ReliefF对人脸图像特征集做特征初选,降低特征维数空间,再用改进的SVM RFE（Support Vector Machine Recursive Feature Elimination）选择最优特征,解决了利用SVM RFE特征选择时因特征数多而算法需多次训练耗时长的问题。对训练得到的特征排序表采用交叉留一验证方法选取最优子集,再由SVM分类识别。在UMIST人脸库上实验证明,可以在特征数为52时,达到98.84%的识别率,识别时间仅需0.037 s。     

丰城矿务局预防煤炭自然发火集成技术

丰城矿务局河西矿区开发于1957年,分布在曲江、上塘、尚庄境内。煤系地层为晚二叠世乐平组,王潘里段和老山段为主要含煤地层,煤系地层总厚500m,从上至下分为C、B、A等3个煤组,其中C、B两煤组有可采和局部可采煤层6层。B煤组含可采煤层3层,其中B4层位稳定,构造简单,煤厚0.6～4.96m,一般为2.5m,是矿区主采煤层。     

批判性地域主义视野下的少数民族民居建筑改造——以云南怒江流域干一它村傈僳族民居为例

在全球文化的“趋同”与地域文化符号化、表皮化的大背景下,以批判的地域主义为理论基础,重新审视该理论对我国少数民族直过区传统民居建筑的保护和传承的适应性发展。通过干一它村傈僳族传统民居建筑改造实践,提出回归本土居民的批判性思考,更多地关注民居建筑物理环境的舒适性、空间组织的地域适应性和地方依恋的地域载体,以弥补当下批判的地域主义实践在系统性考虑本土居民的需求上的缺失,探索传统民居建筑改造如何在传承中创新。     

基于ARM的GPS定位信息系统设计与实现

针对GPS在现实中的广泛应用,结合目前非常热门的嵌入式技术,本文提出了一种以μC／0SⅡ、LPC2292微处理器为软硬件平台,利用SRIFStarⅢ为功能模块的GSP定位信息系统。重点阐述了系统硬件平台的搭建和系统任务的划分,介绍了μC／0SⅡ移植、启动代码以及各个程序模块的设计。实际运行结果表明,该系统能对GPS数据进行正确解码,并在LCD上将定位信息显示出来,系统有较好的可靠性和实用性。     

Ni-P消耗对焊点电迁移失效机理的影响

研究了Cu/Sn/Ni-P线性焊点在150和200℃,电流密度1.0×10⁴ A/cm²的条件下化学镀Ni-P层消耗及其对焊点失效机理的影响.结果表明,在Ni-P层完全消耗之前,阴极界面的变化表现为:伴随着Ni-P层的消耗,在Sn/Ni-P界面上生成Ni₂SnP和Ni₃P;从Ni-P层中扩散到钎料中的Ni原子在钎料中以（Cu,Ni）₆Sn₅或（Ni,Cu）₃Sn₄类型的IMC析出,仅有很少量的Ni原子能扩散到对面的Cu/Sn阳极界面.当Ni-P层完全消耗后,阴极界面的变化主要表现为:空洞在Sn/Ni₂SnP界面形成,Ni₃P逐渐转变为Ni₂SnP,空洞进一步扩展形成裂缝,从而导致通过焊点的实际电流密度升高、产生的Joule热增加,最终导致焊点发生高温电迁移熔断失效.     

Hollow porous poly(lactic acid) microspheres

On the basis of the water solubility of poly(N‐vinyl‐2‐pyrrolidinone), hollow porous poly(lactic acid) microspheres (HPPLAs) were prepared by a water‐in‐oil‐in‐water multiple‐emulsion solvent evaporation method. The influence of the concentration of the stabilizer Span80 in the oil phase on the morphology was investigated. It was found that when the content of Span80 solutions was 3.5 wt %, most HPPLAs were about 2 μm in diameter. Field scanning electron microscopy results show that the HPPLAs were porous and hollow. The structure and crystal form of the HPPLAs were characterized by Fourier transform infrared spectroscopy and X‐ray diffraction analysis. Using these HPPLAs as degradable templates, we successfully synthesized Litchi‐like polystyrene (PS) microspheres about 2 μm in diameter by the emulsion method. When used as drug carriers, these HPPLAs would be convenient in which to embed drugs, whereas the Litchi‐like PS microspheres may have potential as new materials for polymer modification. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

改进教学措施，提高高分子物理双语教学质量

双语教学是高等学校本科教学的大势所趋,如何才能将双语教学工作做好,落在实处是每位高校教师都应该思考的问题。我们通过对高分子物理双语教学工作的总结,结合教学反馈,对教学措施进行了补充和完善。