Wind tunnel tests and numerical simulation on arches’static wind loads of half through arch bridge

Long span half through arch bridges have the flexible space structure. Wind loads on the arches are usually the key factor to the whole bridge. Taking an example of the Chongqing Caiyuanba Yangzi River Bridge in P. R. China, wind tunnel tests of single arch and double arches section models were conducted. The results of a single arch in the smooth flow show that arch drag variability is small, and the lift and moment variability are significantly large. The results of double arches testing show that the static forces of the windward arch are similar to the single arch. The three force coefficients of leeward arches vary with the space width ratio and the angle between the two arches. Static forces testing was simulated by the CFD software FLUENT. The static forces from the testing and the simulation were compared. The results show that the values match quite well with testing, and the drag forces mainly varied with the space width ratio.     

Integrated control technology for methane in mining faces

Methane drainage is an effective technological approach to manage methane in an integrated fashion. Based the actual conditions of the 11031 mining face of the Zhongling coal mine in P. R. China, we divided the origin of methane into three categories: methane of the coal mining layer, methane of the adjacent coal layer, and methane in the goaf. Combining current techniques for managing methane in the mining face, we analyzed the effects of seven methods for draining the methane: through the coal layer borehole, the sector borehole, the cross borehole, the high level borehole, the large diameter borehole, the pipe buried in the goaf, and a special return airway. We suggest improvements for implementing integrated control in the three dimensional space by the control principle of dividing the sources. We provide references for other projects.     

Non linear static analysis of thick reinforced concrete slabs with reinforcements under partitions

There are no clear design standards for the concealed beams or reinforcements under partitions in big and thick slabs which often appear in contemporary reinforced concrete residential buildings. Designers have to rely on engineering experiences to design such concealed beams or reinforcements. We built a local finite element method model of a real building in ANSYS. The model included shear walls, big slabs and partitions, and the underlying reinforcements. The element for reinforcement was Link8, and the others were solid elements. Specifically, the element for big slabs was solid65 which can asses the non linear behaviour of concretes. Based on analysis results, we discuss the internal forces of big slabs, partitions and reinforcements. We offer suggestions for the design of reinforcements and selection of partitions.     

Frequency shift domain iterative analysis for frequency estimation of equilong signals

From the view of trick recognition, features of signal decomposition structure in existing frequency estimation methods were analyzed, based on which, a frequency shift domain decomposition structure was proposed. A compound signal was constructed by combining several simple signals corresponding to different times. The given information in the time domain can be adopted to form an information accumulation effect, such that the interference frequency and noise can be suppressed effectively by decreasing the calculation. To match the use of a frequency shift domain decomposition structure, a frequency shift equilong iterative algorithm suitable for equilong signals was proposed. Simulated experiments were carried out in numerous application environments. The results show better noise immunity and real time performance as well as higher frequency estimation precision.     

Engine crankshaft static strength analysis based on the finite element method

Focusing on the fracture issue of single cylinder engine crankshafts, a three dimensional solid model was built in CATIA. Pre treatments, such as plotting grids, were carried out through Hypermesh, and finite element analysis was done using MSC. Patran/Nastran. The results show that the fatigue safety coefficient cannot meet demand when nodular iron is the crankshaft material. This finding verifies the theoretical possibility of crankshaft fracture. A crankshaft using 40Cr theoretically would not fracture because the fatigue safety coefficient could meet the demand. Simulation correctness was verified by a 400 hour engine reliability test.     

分层土壤的持水性能研究

[目的]本文研究了分层土壤的持水性能。[方法]以砂壤和细砂设计了3种不同分层(2、4和8层)土柱,开展室内饱和排水试验。与均质细砂和砂壤土壤进行比较,观察土柱从饱和到120 h末的持水量变化,测量试验土柱最终含水率剖面,利用HYDRUS-1D软件对分层土柱的入渗过程进行了模拟分析。[结果]砂壤与细砂的土壤分层结构能够提高土体持水能力,增加粗细土壤分层数量有助于提高土柱含水量。试验说明分层土柱的排水主要来自粗质土壤,相对细质土壤排水量较低,反映了粗质土壤上覆细质土壤界面存在的毛细屏障作用能提高上层土壤的持水能力。[结论]本研究对干旱和半干旱地区的水资源综合利用以及土壤修复、污染物填埋等具有一定指导意义。     

农杆菌介导的拟康氏木霉遗传转化及T-DNA插入突变体的筛选

建立并优化了农杆菌介导转化拟康氏木霉(Trichoderma pseudokoningii SMF2)获得T-DNA插入突变体的体系,在木霉孢子浓度106个/mL、农杆菌A600=0.15~0.20、乙酰丁香酮浓度为250μmol/mL的条件下共培养36 h转化率最高,转化子可达60~120个/106个孢子。共获得转化子1 000多个,连续转接5代能够稳定遗传,部分转化子表现为生长和形态异常,PCR验证潮霉素B抗性基因已整合进转化子基因组DNA中。该转化体系的建立为开展其生防机理研究和探索菌株改良奠定了基础。     

辣椒染色体倍性与气孔性状的相关性

以辣椒GT3、GT10和GT16的花药培养再生单倍体植株和其种子植株为试验材料,对叶片的气孔密度、保卫细胞叶绿体数、保卫细胞横纵径等气孔性状进行显微镜观察与统计分析.结果显示:随辣椒染色体倍性的提高,叶片气孔密度呈明显下降趋势;保卫细胞叶绿体数与保卫细胞横径呈明显上升趋势;保卫细胞纵径升高变化不明显.表明叶片气孔密度、保卫细胞叶绿体数、保卫细胞横径可作为鉴定辣椒染色体倍性的有效依据.     

次氯酸钙处理对红富士苹果常温贮藏下防御酶活性的影响

以山东红富士苹果为试材,分析次氯酸钙浸泡处理(0.15 g/L、0.60 g/L)对其常温(17～25 ℃)贮藏120 d内防御酶活性的影响,以多菌灵处理(1.00 g/L)和清水处理为对照.结果表明:次氯酸钙处理可以抑制PPO活性,总体上提高SOD、CAT和POD活性.常温120 d贮藏期间次氯酸钙 0.60 g/L 处理可以比 0.15 g/L 处理提高酶活性或峰值,但差异没有达到显著水平.