Stability of the cleistogamous trait during the flowering period of oilseed rape

At the field scale, the co-existence of different farming production systems requires strategies to prevent gene flow between adjacent crops. Oilseed rape produces pollen dispersed by wind and insects and the risks of pollen mediated gene flow are significant for this crop. Cleistogamy, the trait of non-opening flowers, could be used to reduce pollen flow. Cleistogamous oilseed rape genotypes were obtained by INRA in France and were bred in order to improve the stability of this trait. In this paper, we examine the reliability of the cleistogamous trait for two inbred lines. The flower opening level was measured at different dates during the flowering period in six field experiments (three sites × 2 years). The results showed that some flowers were partially opened with rates varying from 0.5% to 33% principally depending on genotypes, trials (site and year) and recording dates. Given that other studies have shown that cleistogamy could reduce pollen dispersal, we consider that, even when partially unstable, cleistogamy could be beneficially used in combination with other means in a containment strategy.     

Embedded terminal receiving capability matching in multimedia file transmission

A novel transport protocol for large scaled multimedia file EMFTP (Embedded Multimedia File Transfer Protocol) is proposed to match the receiving capability of embedded terminal with sufficient network bandwidth. EMFTP is an application level protocol using UDP, and adopts a method of uniform retransmission as its error recovery strategy and it also introduces an improved DAIMD (AIMD with decreasing increases) rate control algorithm based on bandwidth probe. It can improve the data transfer rate with a low resource taken of embedded client. As the experimental result shows, compared with UDT and FTP protocol implemented on embedded terminal, EMFTP data transfer rate is increased by 3% and 17% respectively, the embedded client CPU occupancy ratios are reduced by 50.3% and 42.3% separately, and memory usage reduced by 15% and 4%.     

Analysis of plastic flow characteristics based on bridge steel 16Mn ratcheting

Abstract:The analysis of the plastic flow characteristics on the basis of the ratcheting experimental results for the bridge steel 16Mn are carried out by calculatig the plastic modulus H and the angle θ between the backstress rate deviator and the plastic flowdirection. The different mechanisms causing uniaxial andmultiaxial non proportional ratchetting are illustrated, that is, the starting and evolution of uniaxial ratchetting is due to the different values of the plastic modulus H at the symmetric loading points with respect to the mean stress. On the other hand, the staring and evolution of multiaxial non proportional ratcheting is driven by H and θ variations. The influence of loading history on ratchetting is the result of the influence of loading history on the angle θ.     

Design optimization of magneto-rheological damper based on finite element parametric language

The mountain hazards like snow avalanches, landslides, rock falls, debris flows and so on all have strong power of destruction which seriously threaten human’s lives and belongings. Therefore, it is necessary to study more the development of these disasters in order to prevent them. Setting up obstacles is the primary measure to control the movement and deposition process of mountain hazards. For the study of the influence of this measure on the development of disasters, the numerical simulation calculation aiming at the flow and deposition process of the granulars flowing past different built obstacles was made by the theory of SH granular flow and the method of finite volume discretization based on Roe's Scheme. Futhermore, the influence of different settings of obstacles on the granular flow is discussed. The numerical results show that the settings of obstacles have a great effect on the process of granular flow. That is, the effective precaution against the disasters is no other than setting up the obstacles correctly. As the numerical simulation calculation can optimize the setting of obstacle, it provides a reasonable and economic reference scheme of disaster prevention and planning of mountain area.     

Mechanical Properties of Concrete Cylinders Confined with CFRP Sheets Subjected to Axial Compression

Based on Drucker-Prager criterion with non-associated flow rule, numerical analysis of mechanical properties of concrete cylinders were carried out by using non-linear finite element method. The effect caused by various parameters such as wrap thickness, fiber orientation and concrete strength on axial mechanical properties of concrete cylinders is discussed. The results show that the results calculated by non-associated flow rule conform to that in the test. It is demonstrated that there is significant enhancement both in compressive strength and ductility of cylinders with the increase of wrap thickness. Moreover, the gain in axial compressive strength is observed to be higher for lower strength concrete and be highest in the cylinders wrapped with the hoop orientation.     

Small scale wind tunnel for high pressure and high energy discharge

A kind of small scale wind tunnel with low velocity is proposed according to the characteristics of strong ionization discharge chamber and the demands of discharge for flux, velocity and flow fields. On the precondition that the airflow field and velocity is satisfied, aerodynamic design and structural design are carried out. Key techniques are studied including overall structure, aerodynamic and structural design of airflow vent and collection vent, aerodynamic and structural design of power section, flow rate adjustment and control, and cooling system of motor. Based on the design scheme, a small scale wind tunnel with strong ionization discharge for an enterprise is developed. Application indicates that the small scale wind tunnel is a practical and effective airflow loop device for high pressure and strong ionization discharge with the features of stability and reliability.     

斑背大尾莺汉口亚种(Locustella pryeri sinensis)遗传多样性及种群结构研究

采用线粒体控制区（807bp）序列分析对中国境内斑背大尾驾3个繁殖种群及1个越冬种群的遗传多样性及种群遗传结构,结果表明：斑背大尾莺的单倍型歧义度（Hd）为0.759±0.056,核苷酸多样性较（π）为0.002。三个地理种群的FST值以及繁殖种群同越冬种群之间的ΦST值表明不同地理单元之间无显著遗传分化。对不同单倍型的聚类分析（UPGMA）结果以及网络图（Network picture）结果也支持不同种群之间无显著分化。分子变异分析 （AMOVA）显示斑背大尾莺汉口亚种不同地理种群间遗传差异不大,98.5%的差异源自种群内部,仅1.5%源自种群间。中性检验结果Fu’sFS值为负值,错配分布分析结果呈单峰,表明斑背大尾驾在我国的进化史经历了种群扩张。这一假设也得到Tajima’D检验和Fu’s检验结果的支持（D=-1.80,p=0.02;Fs=-22.11,p=0.001）,该扩张大约发生在28,700年前。     

国槐枝叶水分特征及其对树干边材液流的影响

为探明国槐Sophora japonica组织含水量、水势、水容等枝叶水分特征及其对树干边材液流的调节和影响,于2007年3月下旬至2008年3月下旬利用热扩散式边材液流检测技术(TDP)、压力室技术等对生长在北京林业大学校园内的国槐树干边材液流、组织含水量、水势、水容等进行了系统研究。结果表明:城市环境下,(1)国槐树干边材液流速率日变化春季和夏季呈双峰曲线,秋季呈单峰曲线;液流峰值出现时间春季最早,夏季次之,秋季最晚;春季和秋季液流速率峰值较夏季高,但峰值维持时间夏季较春、秋两季长。(2)国槐枝条与叶片绝对含水量、水势、水容具有相似的日变化规律,但不同季节日变化有所差异。(3)整个生长季,国槐含水量、水势、水容的大小排序为春季夏季秋季;枝条平均含水量(52.12±2.59)%叶片平均含水量(69.59±4.64)%;枝条平均水势(-1.70±0.74)MPa叶片平均水势(-1.87±0.65)MPa;枝条水容(1.488±3.060)g.cm-3.MPa-1叶片水容(5.86±6.70)×10-3g.cm-3.MPa-1。(4)国槐组织水容日变化与树干边材液流速率日变化反向相关,国槐枝叶含水量、水势、水容等共同作用和调节其蒸腾耗水。     

管板式烘丝机工艺参数对叶丝物理特性的影响

[目的]研究管板式烘丝机及HT工艺参数对叶丝物理特性的影响。[方法]采用均匀设计方法,对管板式烘丝机及HT主要工艺参数进行试验。[结果]热风风门开度对叶丝整丝率有显著影响,热风温度与筒体转速的交互作用和热风风门开度与筒体转速的交互作用对叶丝整丝率有十分显著的影响,热风温度对叶丝整丝率也有较大影响。排潮风门开度、HT工作蒸汽压力与筒体转速的交互作用、热风温度与排潮风门开度的交互作用和热风风门开度与筒体转速的交互作用对叶丝碎丝率有十分显著的影响。热风温度与排潮风门开度的交互作用对叶丝填充值有显著影响,HT工作蒸汽压力与热风温度的交互作用、HT工作蒸汽压力与筒体转速的交互作用和排潮风门开度与热风风门开度的交互作用对叶丝填充值有十分显著的影响。[结论]管板式烘丝机及HT工艺参数对叶丝物理特性影响不尽相同,适当调整工艺参数,可优化叶丝物理结构,提高叶丝使用性能。     

0907号热带风暴“天鹅”复杂路径分析

利用MICAPS常规资料,对0907号热带风暴的复杂路径过程进行分析。结果表明,较弱的引导气流是风暴＂天鹅＂移速缓慢、持续时间长、路径复杂多变的主要原因;东面强台风通过对环境流场的影响对西面的弱台风发生作用,这是＂天鹅＂迂回的另一个主要因素。