A new measurement method for mass property parameters

Mass property parameters (mass, center of mass, moment of inertia) are important technology parameters of aircraft. The traditional mass and center of mass measurement uses centroid units, and the moment of inertia measurement torsion units, which can only get results in installing direction. Because of the structural reasons, there is a need to get all high accurate physical parameters in clamping once. To solve this problem, this study merges centroid units and torsion units into one composite unit, installs a table which can tilt and rotation to measure the moment of inertia in different conditions. The moment of inertia and product of inertia relative to three axis are calculated by the method of coordinate transformation. Measurement theory of mass, center of mass and mass moment of inertia are described, the main reason of causing measurement errors is discussed, and the measurement accuracy affected by tilt error is analyzed.     

肺部炎性假瘤（附28例误诊分析）

１９７８年９月至１９９４年７月，我科对肺炎性假瘤３０例施行手术治疗，术前误诊高达２８例，占９３．３％。３０例中男２１例，女９例，平均年龄５３．４岁，这与文献报道有显著不同。本文从ＩＰＬ临床表现，Ｘ线征象及手术所见等方面对可引起误诊的因素进行了仔细分析。提出了减少误诊的措施，并对ＩＰＬ的预防和治疗作了讨论。     

出眠初期甲鱼肺泡、胃、肝细胞结构的电镜观察

通过扫描和透射电镜观察，描述了出眠初期甲鱼的肺、胃、肝细胞的超微结构特征。肺呈泡囊状结构，由肺泡隔将肺内部隔开成海绵状结构，肺泡内表面覆盖一层呼吸上皮，由单层上皮细胞和毛细血管网构成。上皮细胞有两种类型：Ⅰ型上皮细胞胞质向四周延伸成极度扁平状；Ⅱ型上皮细胞近核细胞质里分布有一定数目的多层体，多层体体积较大，由Ⅰ型上皮细胞延伸的胞质薄层、融合的基底膜和毛细血管内皮细胞胞质薄层共同构成血－气屏障。胃粘膜表面有许多胃小凹，粘膜上皮细胞内有许多电子密度深的分泌颗粒，粘膜腔面被一层粘液所覆盖。肝细胞有两种不同类型，即Ｌ细胞和Ｄ细胞，Ｌ细胞胞核呈圆形，细胞质多，近核周围有一些线粒体；Ｄ细胞的核形状不规则，细胞核紧抱一巨大的脂滴，细胞质较少，细胞器不发达。     

设计偏心距对偏心结构弹塑性扭转反应的影响

通过对三片抗侧力单元构成的偏心结构进行弹塑性时程分析,研究了弹塑性侧扭耦合反应与输入地震动强度之间的关系.随着输入地震动强度的增大,结构扭转反应经历3个阶段的变化,在弹性范围内扭转角单调增大,开裂后逐渐减小,屈服后则继续增大.扭转对侧向振动的影响则逐渐减小,侧扭耦合程度逐渐降低.分析结果表明:通过设计偏心距对偏心结构进行强度分配,可以控制弹塑性扭转反应并提高结构侧向变形能力.设计偏心距的不同取值,对刚性边构件的屈服水平和延性需求的影响最大.文章还对偏心结构基于性能的抗震设计进行了展望.     

驱动轴最大静扭强度与表面淬硬层状态关系浅析

拖拉机驱动轴的最大静扭强度和表面淬硬层状态具有直接关系,并进而直接影响驱动轴的疲劳强度。表面淬硬层不连续会使驱动轴的疲劳强度大幅降低而造成驱动轴早期断裂、失效;驱动轴表面淬硬层不连续会使其最大静扭强度降低30%以上;表面淬硬层过浅也会降低最大静扭强度。     

二甲苯对小鼠肺组织损伤的初步研究

为了研究二甲苯对小鼠肺组织的损伤情况,以健康成年小鼠作为试验动物,分3个试验组(低、中、高剂量组)1个对照组,给试验组腹腔注射不同剂量二甲苯(0.125、0.25、0.5 mL/kg),给对照组腹腔注射生理盐水.15 d后剖检取材,采用石蜡切片和HE染色技术研究二甲苯染毒后小鼠肺组织结构的变化特点;采用分光光度法测定小...     

SIDE LOBES AND GRATING LOBES ARTIFACTS IN ULTRASOUND IMAGING

Side lobes and grating lobes are both unwanted parts of the ultrasound beam emitted off axis that produce image artifacts due to error in positioning the returning echo. The purpose of this study was to reproduce artifacts associated with side lobes and grating lobes in vitro using different transducer types and recognize these artifacts in vivo. A phantom, composed of a water bath, a metallic wire, and a wooden tongue depressor, was imaged using a linear array, a curved linear array, a vector array, and a sector mechanical transducer. When imaging the metallic wire in a transverse plane, an echogenic artifact was constantly seen on each side of the wire, with a shape and intensity variable with the transducer type. The artifact was curvilinear and concave (linear and curved linear arrays), or curvilinear and convex (vector array and the mechanical transducer). When the tongue depressor was imaged in a longitudinal plane, the artifact was a straight line (linear array), a curved convex line(curved array), a series of convex curvilinear echo (vector array) or a small convex curvilinear echo (mechanical transducer). In vivo situations similar to the phantom experiment were investigated using clinical patients. Artifacts produced in vitro were recognized in vivo when a highly reflective object (urinary bladder wall) was imaged adjacent to an anechoic region (urine). These artifacts corresponded to the principle of secondary ultrasound lobes, and were therefore interpreted as such.     

Characterization of normal tidal breathing flow-volume loops for Thoroughbred horses

The purpose of this study was to characterize the normal equine tidal breathing flow-volume loop (TBFVL). The study was performed using 18 healthy Thoroughbred horses. TBFVLs constructed from data collected from resting horses had a typical biphasic inspiratory and expiratory phase. The interindividual variability of the indices used to describe TBFVLs was in the range 16–32%, which is comparable to the variability of other measures of equine pulmonary mechanics. The large variability of these data probably limits the value of resting TBFVL indices for detecting subclinical respiratory conditions in individual horses. Factor analysis of these data revealed that in excess of 90% of the variance of the initial response variables could be explained in terms of three common factors. Varimax rotation of these three common factors provided three subsequent factors that were readily identifiable as (1) a factor describing the time-volume relationships of TBFVLs, responsible for 81% of the total variance, (2) a factor explaining the expiratory portion of the TBFVL, explaining 12% of the variance, and (3) a factor describing the inspiratory portion of the loops, responsible for the remaining 7% of the variance. The analysis also provided standardized factor scoring coefficients for use in subsequent studies using similar experimental techniques.Abbreviations EF₂₅ expiratory flow at expiratory volume plus 25%V _E - EF₅₀ midtidal expiratory flow - f respiratory rate - IF₂₅ inspiratory flow at 25% of inspiratory volume - IF₅₀ midtidal inspiratory flow - MSA measure of sampling adequacy - PEF peak expiratory flow - PIF peak inspiratory flow - TBFVL tidal breathing flow-volume loop - T _E expiratory time - T _I inspiratory time - USPTM ultrasonic pneumotachometer - V _E expiratory volume - V _I inspiratory volume     

COMPUTED TOMOGRAPHY DIAGNOSIS OF ISOLATED SPLENIC TORSION IN A DOG

Isolated splenic torsion in a dog was diagnosed using computed tomography (CT). The enlarged non enhanced spleen and a twisted soft tissue mass effect represented the rotated pedicle were the main findings. Abdominal radiography and ultrasonography were not conclusive.