Initiation and development of water film by seepage   总被引：1，自引：1，他引：0  

Xiaobing Lu  Peng Cui  Kaiheng Hu  Xuhui Zhang 《山地科学学报》2010,7(4):361-366

When water seeps upwards through a saturated soil layer,the soil layer may become instability and water films occur and develop.Water film serves as a natural sliding surface because of its very small friction.Accordingly,debris flow may happen.To investigate this phenomenon,a pseudothree-phase media is presented first.Then discontinuity method is used to analyze the expansion velocity of water film.Finally,perturbation method is used to analyze the case that a water flow is forced to seep upwards through the soil layer while the movement of the skeleton may be neglected relative to that of water.The theoretical evolutions of pore pressure gradient,effective stress,water velocity,the porosity and the eroded fine grains are obtained.It can be seen clearly that with the erosion and redeposited of fine grains,permeability at some positions in the soil layer becomes smaller and smaller and,the pore pressure gradient becomes bigger and bigger,while the effective stress becomes smaller and smaller.When the effective stress equals zero,e.f.liquefaction,the water film occurs.It is shown also that once a water film occurs,it will be expanded in a speed of U(t)(1-ε).  相似文献   

MSCT和X线平片在诊断腰椎滑脱症中的临床价值比较   总被引：3，自引：1，他引：2  

付传明  陈义加  陈学强  陈伦刚  邹建华  吴文强 《CT理论与应用研究》2010,19(3):67-73

目的:比较X线平片和多排螺旋CT诊断腰椎滑脱的准确性,并评价临床价值。方法:搜集40例经X线平片、MSCT检查诊断并手术治疗的腰椎滑脱患者,X线平片和MSCT判定腰椎滑脱程度、部位、类型的结果与手术对照。结果:40例患者,27例手术证实为真性滑脱,13例为假性滑脱。以手术为对照,X线平片、MSCT诊断腰椎滑脱程度和部位准确率为100%;X线平片判定腰椎滑脱类型的敏感性、特异性、阳性和阴性预测值为分别为59.3%、100%、100%和54.2%;MSCT判定滑脱类型的敏感性、特异性、阳性和阴性预测值均为100%;X线平片和MSCT对滑脱类型判定具有明显统计学差异(P0.01)。结论:X线平片、MSCT判定腰椎滑脱程度和部位均具有较高的准确性;判定腰椎滑脱类型,MSCT比X线平片好,X线平片目前仍是基本的筛查方法,MSCT进一步明确腰椎滑脱类型诊断,为临床提供更多的影像信息和治疗方案。  相似文献   

Radiation energy flux of Dirac field of static spherically symmetric black holes     

孟庆苗  蒋继建  李中让  王帅 《海洋学报(英文版)》2010,29(9)

By the statistical entropy of the Dirac field of the static spherically symmetric black hole, the result is obtained that the radiation energy flux of the black hole is proportional to the quartic of the temperature of its event horizon. That is, the thermal radiation of the black hole always satisfies the generalised Stenfan--Boltzmann law. The derived generalised Stenfan--Boltzmann coefficient is no longer a constant. When the cut-off distance and the thin film thickness are both fixed, it is a proportional coefficient related to the space--time metric near the event horizon and the average radial effusion velocity of the radiation particles from the thin film. Finally, the radiation energy fluxes and the radiation powers of the Schwarzschild black hole and the Reissner--Nordstrõm black hole are derived, separately.  相似文献   

照相透镜重镀增透膜及使用情况     

钟树华  张霄宇  陈学昆 《天文研究与技术》1998,(1)

介结了云南天文台太阳光谱仪１９８８年进行的重镀１１块照相透镜增透膜以及镀膜后的使用情况。重镀增透膜前照相透镜的透过率已降低到７７％～８４％,重镀后提高到９２％～９８％。相对于镀膜之前的透过率数值提高１４％～２６％,照相露光时间缩短１倍左右。  相似文献   

铜合金在海水中电化学阻抗谱特征研究   总被引：5，自引：0，他引：5  

赵永韬  李海洪  陈光章 《海洋科学》2005,29(7):21-25

利用电化学阻抗谱(EIS)对紫铜和铜镍合金在静止、洁净海水中表面成膜的过程进行了监测，根据不同阶段的EIS特征建立不同等效电路模型进行拟合分析。获得了铜合金基体及其表面膜层对应的界面电化学信息参数，通过比较3种金属(B10，TUP，B30)表面膜层随时间变化的差异。探讨了合金成分对表面成膜过程的影响。结果表明。浸泡前期B10和TUP的耐蚀性较差，但随着海水中浸泡时间增加，三者的耐蚀能力逐渐接近。TUP的EIS显示了其表面内、外膜层信息。B10表面膜层的成长速度和稳定性均不如B30，反映出合金中镍含量的增多，增加了铜镍合金表面成膜产生钝化的效应。  相似文献   

Distorted polyester lines for model testing of offshore moored platforms     

A.C. Fernandes  R.R. Rossi 《Ocean Engineering》2005,32(7):817-825

Model tests of floating offshore platforms replace the mooring lines by inextensible cables connected to steel springs with a linear restoring capability. With the help of fundamental investigation on the similarity laws, the present work shows that the use of very thin polyester lines in model scaling is feasible and may allow a better physical representation of the full-scale polyester lines. The proposal is to use polyester lines with length distortion in order to keep the similar restoring capability and therefore, the same non-linear behavior would also be present during the tests. The work describes the application of these ideas in a model test of an Floating Production Storage and Offloading (FPSO) submitted to regular and random waves. The tests include both the linear spring lines and the distorted equivalent polyester lines, holding the FPSO model, submitted transversally to the same waves.  相似文献   

用塑料薄膜袋进行一级藻种培养的研究   总被引：1，自引：1，他引：1  

于瑞海  潘振球  王昭萍 《海洋科学》1990,14(4):62-63

本文主要介绍用塑料薄膜袋代替1—2×1O~4mL细口瓶来进行饵料一级藻种培养,此法保证了扇贝育苗所需大量饵料的优质藻种,简单易行。 Ⅰ.材料与方法 Ⅰ.1.制袋的材料和方法 采用直径30cm,长度120cm的聚乙烯透明  相似文献   

水面浮油膜光谱测量及光谱特征分析     

刘旭拢  邓孺孺  秦雁  梁业恒  刘永明 《海洋科学》2016,40(10):63-70

为深入解析水面浮油膜光谱特征,采用水面以上光谱测量方法,去除太阳直射和天空光两部分反射的影响,获取了珠江口水域不同厚度水面柴油膜光谱信息,对其光谱响应特征和机理进行了分析。结果表明:水面柴油膜光谱对背景水体光谱具有依赖性,但水面柴油膜光谱在可见光波段高于背景水体,且随着油膜厚度增加呈现不断增加的趋势;油膜反射光谱在蓝、紫光区域出现明显反射峰;360~500 nm区域油膜反射率与厚度相关系数大于0.8,有利于油膜厚度的遥感估算。最后指出,水面浮油膜类似于光学薄膜的单层增反膜,导致光谱反射率的增加,在360~420 nm区域的反射峰和石油类物质的荧光性有关。研究结果可为水域溢油污染遥感监测研究提供理论依据。  相似文献   

大电流密度下阴极产物膜的探讨   总被引：4，自引：0，他引：4  

朱锡昶  葛仁淦  朱颖 《海洋工程》1997,(1)

在室内和现场不同大电流密度下形成阴极产物膜，通过观察膜的形貌、厚度、强度、分析成份，对其进行电位衰变试验、阴极极化试验、生锈试验及维持保护电流试验，进行分析比较，同时对涂层和阴极保护联合防腐时涂层破损、剥落处阴极产物膜的形成，及其对电流密度、保护电位的影响作了探讨。本文还对阴极产物膜的应用价值，以及在阴极保护中应用的可能性作了阐述。  相似文献   

黑色地膜对马铃薯产量及土壤质量的影响     

周丽敏  张皓  李琪  韩媛  谢佳 《南京气象学院学报》2016,8(4):316-321

在半湿润的南京地区,以微型马铃薯荷兰七号为指示作物,采用平地起垄覆膜的种植方式,分别选用黑色地膜（BM）与普通白色地膜（WM）做比较,并以不覆膜的平地作为对照（CK）,分析不同处理对微型马铃薯生理指标、产量以及种植区土壤质量的影响.发现BM处理下微型马铃薯的淀粉质量分数和产量最高,较WM处理增产31.1%,较CK增产43.7%;覆膜处理显著降低了耕层土壤的速效钾质量分数,BM处理下耕层土壤的速效磷质量分数最低,但土壤铵态氮与硝态氮质量分数显著高于其他处理;覆膜处理有效提高了微型马铃薯出苗期的耕层土壤含水量,BM处理下微型马铃薯生育期内的表层土壤温度明显低于WM,且高于对照,对微型马铃薯的生长更有利.  相似文献