基于RSM模型的螺旋管道内二次流特性分析

利用FLUENT流体力学软件,采用RSM模型对矩形截面螺旋管道紊流流动中的二次流进行数值模拟。分析研究表明,矩形螺旋管道不同管轴半径连接断面上明显出现一对二次涡,且两个二次涡位于中心略微偏向外边壁,其结果与目前所研究的二次涡所在位置有区别;而且随着雷诺数的增大,二次涡的位置变化不大;随着管道曲率的增加,二次流强度逐渐增大,而随着雷诺数的增大,二次流强度却有所减小。     

Effects of Air Temperature and Humidity on Particle Deposition in a Ventilation Duct

Particle deposition in a fully developed turbulent flow of ventilation duct with a rectangular cross section of 0.3 m×0.2 m and 3 m in length was investigated. The effects of thermophoretic force and air humidity were also considered. Trajectories of 3 000 particles were tracked on the basis of the random walk model from Lagrangian approach. The profile of dimensionless deposition velocity with relaxation time was achieved and the comparison with the previous studies was made with particle size range of 0.01 50 μm and air flow velocity of 5 m/s. It is found that the trend of dimensionless deposition velocity is in agreement with the previous studies and the profile of dimensionless deposition velocity showed a V shaped curve. The effects of temperature and air humidity were also investigated with particle size of 1 μm. Thermophoretic force caused by temperature gradient between air flow and wall surface accelerated particle deposition. Meanwhile, it is also found that the deposition velocity increases with the increase of air relative humidity.     

5种松树针叶解剖结构的数量分析

巴山松的分类地位迄今仍未明确,为了揭示巴山松与其近缘种的亲缘关系,运用统计学方法,对巴山松、油松、马尾松、黄山松、云南松5种亲缘关系相近松树的14个居群200多个个体的20项针叶解剖结构特征进行筛选、测量和分析。结果表明,这5种松树具有较高的多样性水平;巴山松和油松虽具有相似的结构特征和较近的亲缘关系,但运用数量分析法对群体间特定解剖特征量进行分析仍可以将二者区分开来,因此研究结果更支持巴山松为独立分类单元。研究还发现,树脂道在松属植物分类中具有重要意义,并摸索出一套适合松属植物解剖结构研究的数量分析法。     

一次台风过程大气波导特征分析

在介绍大气折射和大气波导类型的基础上,分析了3类大气波导形成的气象条件。以出现在南京地区的大气波导为例,从探空资料、天气图和NCEP再分析资料出发,对受台风影响的大气波导特征进行了综合分析;对湿度场和散度场分析表明,湿度递减以及辐散下沉运动是大气波导发生的主要原因。     

林木抗旱性与其根次生构造关系的研究

按照林木一年生根系的次生构造,特别是根横切面木质部与韧皮部面积之比,导管与木质部面积之比以及导管与根径面积之比,对林木的抗旱性进行综合评价,从遗传特征上揭示各种林木抗旱性的差别。按照这３个指标对８个常见造林树种的抗旱性进行综合评价,从强到弱依次是：刺槐＞旱柳＞紫穗槐＞臭椿＞毛白杨＞白榆＞白蜡＞沙棘。     

CORRELATION BETWEEN THORACIC RADIOGRAPHIC CHANGES AND REMISSION/SURVIVAL DURATION IN 270 DOGS WITH LYMPHOSARCOMA

A retrospective study was undertaken wherein the medical records and thoracic radiographs of 270 dogs with lymphosarcoma were reviewed to determine the type and frequency of thoracic radiographic changes. Statistical evaluation of the relationship between radiographic, clinical and immunologic factors and the primary remission duration and survival times was performed using univariate and multivariate analysis. One hundred ninety-two dogs (71 %) had some type of thoracic radiographicabnormality, including 80 dogs (29.6%) with pulmonary infiltrates and 164 dogs (64.4%) with thoracic lymphadenomegaly. Only T-cell phenotype (p = 0.0056 for survival, p = 0.0045 for remission) and the presence of cranial mediastinal lymphadenomegaly (p = 0.0005 for survival, p = 0.0129 for remission) were identified as having a significant negative correlation to both primary remission and survival duration by multivariate analysis.     

Partial esophagectomy with single layer closure for treatment of esophageal sarcomas in 6 dogs

OBJECTIVE: To report partial esophagectomy (PE) as a treatment for esophageal sarcoma in dogs. STUDY DESIGN: Retrospective study (2000-2002). ANIMALS: Six dogs with caudal thoracic esophageal tumors. METHODS: Medical records of 6 dogs that had surgical removal of esophageal tumors were reviewed. Signalment, medical history, physical examination results, complete blood count, surgical procedure, tumor classification, postoperative treatment, and complications were retrieved. RESULTS: Esophageal masses were approached by thoracotomy and esophagotomy on the side opposite the mass, removed with 1 cm margins by full thickness excision, and the defects closed with a single layer of interrupted sutures. All dogs recovered rapidly without major complications. Tumors were fibrosarcoma (3 dogs), undifferentiated sarcoma (1), and osteosarcoma (2). Five dogs were administered doxorubicin chemotherapy after surgery. Good quality of life was observed postoperatively in 5 dogs until deterioration necessitated euthanasia; survival ranged from 2-16 months. The remaining dog was alive, 20 months after surgery. CONCLUSIONS: Partial esophagectomy and closure using 1 suture layer, was an effective, simple, and safe technique for removal of sarcomas of the distal thoracic esophagus. CLINICAL RELEVANCE: Removal of esophageal masses by partial esophagectomy can be used reliably as a method of esophageal surgery.     

CARDIAC AND PULMONARY ARTERY MENSURATION IN FELINE HEARTWORM DISEASE

A retrospective study was undertaken to quantify thoracic radiographic changes in cats with heartworm diseases, ( Dirofilaria immitis ). Using a blinded study format, the cardiac silhouette, thoracic cavity and pulmonary arteries were measured from thoracic radiographs of 21 cats with feline heartworm disease and 30 cats without known cardiac or pulmonary vessel pathology. Measured data were normalized to the thoracic cavity or bony structures within the radiographic field of view. The measurements were compared between the two groups of cats using an unpaired, two-tailed Student's t -test, with a p value of < 0.05 being considered significant. Cats with feline heartworm disease had enlargement of the craniocaudal aspect of the cardiac silhouette and normalized cardiac:thoracic ratio (p < 0.05) on the lateral view. Also, there was significant enlargement of the central and peripheral caudal lobar pulmonary arteries and their normalized ratios (p < 0.05) in the heartworm infected cats as visualized on the ventrodorsal projection. Tortuosity of the pulmonary arteries was seen in three of the 21 infected cats. Eleven of the 21 cats with feline heartworm disease had pulmonary parenchymal changes. Based on the present study, central and peripheral pulmonary artery enlargement as viewed on the ventrodorsal radiograph was the single best radiographic indicator of feline heartworm disease.     

Unilateral exophthalmia in a European hedgehog (Erinaceus europaeus) caused by a lacrimal ductal carcinoma

A 5-year-old European hedgehog was examined because of exophthalmos of the left eye. A retrobulbar mass in the ventromedial orbit was suspected and confirmed by a computed tomography scan. Exophthalmos progressed despite systemic broad-spectrum antibiotic therapy. The left orbit was exenterated and the mass was partially removed. The histopathologic diagnosis was lacrimal ductal carcinoma. Lacrimal ductal carcinoma is rare in humans and animals. The long-term prognosis is guarded to poor.     

A COMPARISON OF NORMAL FELINE THORACIC RADIOGRAPHS MADE IN DORSAL VERSUS VENTRAL RECUMBENCY

Thoracic radiographs of 11 normal cats were made in dorsal (VD) and ventral (DV) recumbency with a vertically directed x-ray beam. These radiographs were compared subjectively and objectively with each other and with an additional pair of radiographs made with the cats in dorsal and ventral recumbency using a horizontally directed x-ray beam. Differences were found between VD and DV thoracic radiographs but they were minimal. In VD radiographs the caudal mediastinum and accessory lobe regïon of the lung were more clearly seen but cardiac shape varied somewhat. In DV radiographs, the appearance of the heart was more constant and caudal lobar pulmonary arteries more clearly seen. The results of this study indicated that both VD and DV radiographs are satisfactory for radiographic examination of the feline thorax