用穿插HDPE管衬里技术修复城市埋地燃气旧管道

介绍了旧管道免开挖修复新技术－－穿插HDPE管内衬修复旧管道在燃气管道修复中的应用，并对它的应用前景作了分析。     

前排座椅参数设计对后排乘员的安全性仿真分析

为了研究前排座椅参数对后排乘员在正面碰撞时的安全性影响,使用碰撞软件MADYMO建立包括车体、5%女性假人、安全带在内的某款轿车后排乘员正面碰撞仿真模型。通过试验样车碰撞结果与模型仿真结果的对比,验证模型有效性。在此模型基础上,分析前排座椅头枕和靠背参数对后排乘员的HIC、胸部3ms、胸部压缩量和左右大腿力的损伤值影响,得到了前排座椅参数与后排乘员伤害值的关系,提出减小后排乘员伤害的方法。     

边缘模型基背景区的JPEG压缩方法研究

模型基编码是目前极富前途的低比特率图象压缩方法之一 ,而边缘模型基方法较之通常的模型基方法有更多的优点 ,正逐渐引起研究人员的注目 .在边缘模型基中 ,除去了图象中大部分高频分量的背景区 ,其灰度变化较缓慢 ,这些被去除了的空域 ,大小大约占整个图象的 10 % .为了能采用传统的 JPEG方法 ,对背景区进行静态压缩 ,提出了一种简易的基于 8× 8子块的直流分量激励区填充方法 .实验表明 ,用该方法得到的填充后的图象十分适合 JPEG压缩 ,且可以得到较高的压缩比 ,同时图象的主观质量也优于直接对未填充图象做 JPEG压缩 .     

γ射线对叶组织电阻变化的影响及动态分析

测试了水稻和烟草两种叶片经不同剂量的^60Co γ射线辐照处理后，组织电阻及离子外渗的动态变化情况。研究结果表明：当超过一定的剂量阈值后，随着辐照剂量的增加，两种植物的叶组织电阻均呈现先上升、后下降的变化规律；叶组织电阻的改变与离子外渗的变化趋势并不一致；用测量叶组织电阻的方法可以较灵敏地体现出植物对γ射线的动态反应情况。运用电生理学的基础理论对上述生理现象的产生原因从机理上进行了分析与探讨。     

Porous-coated total hip replacement

Fifteen years of clinical experience with porous-coated prostheses demonstrated the durability of this type of fixation. This experience was documented by clinical follow-up study of the 393 cases treated by the senior author before 1985. Only six of these femoral components have been revised: three for loosening, two for stem breakage, and one for infection. Thus, the revision rate for the porous-coated stems was 1.5%. Porous-coated acetabular components were used in 227 of the arthroplasties. Five of these porous-coated cups have been revised: four for malposition leading to dislocation and one for late loosening secondary to osteolysis. Thus, the revision rate for these porous-coated acetabular components was 2.2%. Twenty bipolar and 146 cemented acetabular components were used in the remaining 166 cases treated before 1985. Eleven (7.5%) of the cemented acetabular components were revised. Revisions of the porous-coated components were rare in the first ten postoperative years. The clinical data were supplemented with analysis of postmortem specimens from 15 patients. Mechanical testing of the femoral specimens showed the relative micromotion at the porous surface to be exceptionally small (less than 40 microns). Seven of these postmortem retrievals involved cases with unilateral arthroplasties. In these cases, the contralateral normal femur also was removed, and a prosthesis identical to that in the in vivo implanted side was inserted to simulate the immediate postoperative condition. Dual-energy X-ray absorptiometry (DEXA) of the seven paired femora demonstrated that bone remodeling can be expected to produce a 5%-52% loss of periprosthetic bone mineral content, with the greatest loss occurring in the more osteoporotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dynamic external fixation for distal radius fractures

Thirty adult patients with closed comminuted and mostly intraarticular fractures of the distal radius were treated by closed reduction and immobilization with a dynamic external wrist fixator during a 2-year period. In 13 patients with severely comminuted and unstable fractures, additional Kirschner wires were used. After 10 to 14 days of rigid fixation in neutral position, the motion element was unlocked to allow up to 30 degrees flexion. Six weeks later, the fixator was removed. The patients then were observed for an average of 24 weeks. An excellent functional outcome was seen in 6 patients (20%), a good outcome in 20 patients (67%), and a fair outcome in 4 patients (13%). Anatomically, 15 patients (50%) had an excellent result, 14 (47%) a good outcome, and 1 (3%) a fair outcome. Only minimal loss of reduction averaging 1 degree palmar tilt was seen during mobilization. There were 2 major complications: 1 deep Kirschner wire tract infection and 1 index metacarpal fracture. Minor complications such as sensory disturbances and pin tenderness were present but recovered completely after removal of the fixator. This study provides promising data and offers an alternative method in the treatment of distal radius fractures with severe comminution. In cases with postreductive unstable fragments, additional Kirschner wires should be used to allow early mobilization of the wrist.     

表面预氧化镍钛丝微弧氧化涂层的研究

通过微弧氧化法(MAO)在表面预氧化镍钛(NiTi)丝(直径(0)0.5mm)表面制备含Ca、P的均匀微孔涂层,对不同处理时间形成的涂层进行扫描电镜(SEM)形貌观察和电子探针(EPMA)成分分析,并探查了涂层的血液相容性.实验结果表明,表面预氧化的NiTi丝在微弧氧化处理时,随微弧氧化时间的延长,氧化层中Ti/Ni提高,Ca、P含量也提高.微弧氧化20s时,涂层质量较好,微孔均匀分布,微孔孔径1μm左右,表面没有裂纹,而且此时涂层有较好的生物相容性.     

高效液相色谱法检测牛奶及其制品中的溶菌酶

目的建立一种测定牛奶及奶酪制品中低含量溶菌酶的高效液相色谱-荧光检测新方法。方法样品经p H 6.0的氯化钠溶液活化,再在低p H值条件下除蛋白后,采用反相色谱柱(PLRP-S 250 mm×4.6 mm,300?,5μm)用A水(0.1%的三氟乙酸(trifluoroacetic acid,TFA)),B乙腈(0.1%TFA)体系作为流动相进行梯度洗脱,使用荧光检测器在激发波长(λ_(ex))276 nm,发射波长(λ_(em))345 nm处检测。结果最优实验条件下,溶菌酶在2.0~30.0 mg/L浓度范围内线性良好,加标实验结果显示回收率和相对标准偏差(relative standard deviation,RSD)分别在92.3%~104.3%和0.81%~3.26%之间,对牛奶和奶酪制品的检出限分别为20和40 mg/kg。结论该方法操作简便,结果准确、可靠,可用于乳制品中溶菌酶含量测定。     

巨大晶胞化合物Ho117Fe52Ge112的结构磁性能研究

利用X射线衍射技术和振动样品磁强计（VSM）研究了巨大晶胞三元化合物Ho117Fe52Ge112的结构与磁性能,测定了外加磁场为0．5T时该化合物的磁矩随温度的变化关系。该化合物具有Tb117Fe52Ge112结构类型,空间群为Fm3m（No．225）点阵参数为a=2．80832（8）nm。在90K到室温的范围内,Ho117Fe52Ge112的磁化率与温度关系服从居里——外斯定律,每个化学式有效磁矩的实验值为ueff=111．25us。测定了室温（300K）时磁矩随外加磁场的变化关系。当外加磁场到2．1T时,该化合物的磁矩约为3．61emu／g,还没有达到饱和状态。     

基于非平稳周期循环特征增强的柴油机失火故障诊断研究

利用缸盖振动信号诊断柴油机失火故障时,由于柴油机工作背景噪声复杂,必须消除信号中的非周期分量和随机干扰,保留与柴油机工作循环有关的周期分量。提出一种非平稳周期循环特征增强方法,首先利用连续小波变换实现信号的时-频表示,进一步将信号的时-频特征映射到角-频空间上某一角度范围内,实现了周期瞬态特征的增强;最后,通过角-频空间中各缸工作相位内的能量与整个角度范围内能量之比,实现柴油机失火故障缸的准确定位。