Impact of wetting agents,time of day and periodic energy dosing strategy on the efficacy of hot water for weed control

To further increase the cost‐effectiveness and sustainability of hot water weed control, the further optimisation of hot water efficacy is needed. Therefore, three dose–response experiments were carried out to evaluate the impact of wetting agents (an ethoxylated triglyceride, an esterified rapeseed oil and a liquid linseed oil‐based soap), time of day (2, 4, 6, 8, 10 and 12 h after sunrise) and treatment frequency (1–6 treatments in a 12 week period) on the hot water sensitivity of prevalent weed species (Lolium perenne, Festuca rubra, Taraxacum officinale and Plantago major) on public pavements. Generally, wetting agents did not improve hot water sensitivity. Taraxacum officinale with large planophile leaves showed a higher sensitivity than grasses with an erectophile growth habit. Festuca rubra was more sensitive than L. perenne due to its high leaf dry matter content. The plant species were most sensitive to hot water in the afternoon. This variation in sensitivity during the day was related to the variation in leaf thickness and dry matter content. In general, hot water weed control was highly efficient when conducted four times in a 12 week period at an energy dose of 589 kJ m^?2.     

蚯蚓非光滑体表形貌与降阻特性

以赤子爱胜蚓(Eisenia foetida)为研究对象,制备了舒张态、静息态、收缩态3种体表试样。利用OLYMPUS体视显微镜及OLYCIATMM3图像分析系统,对蚯蚓体表形貌进行分析,结果表明蚯蚓体表形貌属于典型的波纹形非光滑结构,体部纹理小而密,非光滑单元密度较大,头部纹理大而稀,非光滑单元密度较小。头部舒张态、静息态、收缩态非光滑结构单元体宽度和高度之比分别为1.65︰1︰0.78和0.23︰1︰1.27;而体部舒张态、静息态、收缩态非光滑结构单元体宽度和高度之比分别为1.65︰1︰0.81和0.33︰1︰1.28。利用微黏附力测试系统,对蚯蚓体表展平试样和钢试样进行土壤滑动阻力试验,结果表明蚯蚓体表试样的降阻效果由大到小依次是收缩态、静息态、舒张态;而且,头部比体部降阻效果明显;与钢试样相比,头部和体部收缩态的降阻率分别为39%和29%。该研究可为生物非光滑表面仿生研究以及揭示蚯蚓体表形貌和润滑耦合仿生机制提供基础数据。     

Ability of plant-based surface technology to improve urban water cycle and mesoclimate

The presented study proposes a technology that could be used in developing a stormwater management strategy. The research was conducted under the hypothesis that a plant-based surface system (PBSS) can increase the capacity of sealed urban surfaces, for example, along railway tracks, to reduce runoff volume, to increase evaporation and consequently to improve the mesoclimate. To test this statement, water retention capacity, runoff–precipitation ratio, runoff delay and evapotranspiration performance were determined for different time periods (rainwater events, daily, monthly, seasonally, yearly, and throughout the entire measuring period of 18 months) by means of a measurement strategy implemented in selected urban traffic areas of Berlin, Germany, that contained railway tracks. Additionally, a computation of the air humidity improvement of an urban test location based in measurements is presented. The main elements of the tested PBSS were a 2 cm thick vegetation mat and a 20 cm thick drainage layer. The measurement strategy for the hydrological characterization included the installation and use of weighable lysimeters, rain gauges and runoff volume counters. The runoff volume determined in some summer months for the PBSS technology amounted to 9% of precipitation. The evaporation performance in these months amounted to 100% of precipitation. These results were compared with the corresponding calculated values for an asphalt surface: runoff 70–80% of precipitation and evaporation performance of 20–30% of precipitation. The study provides evidence of the positive effect of this technology on the local water balance of the treated sealed areas.     

正螺旋面展开图的几何优化设计

提出了一种正螺旋面解析设计计算方法,按照绝对变形量和相对变形量指标为最小两类目标函数建模,导出了在相应加工条件下的设计计算公式。实际应用结果证实了该设计思想的正确性。     

Surface Reconstruction and Modification of Port-Combustion Chamber Structure for a Gasoline Engine

Geometry of port-combustion chamber has an important effect on the performance of gasoline engines. Methods and approaches in reverse engineering are introduced into surface reconstruction and modification of a port-combustion chamber structure. Free-form surfaces of the port-combustion chamber structure for a gasoline engine with 4-valves and dual-ball type combustion chamber are successfully reconstructed in the reverse way through data processing, surface modeling, surface verifying, surface re-modeling and smooth evaluating etc., based on laser-scanned point cloud data of a sample work piece. It lays a foundation for imitation innovation of gasoline engine by changing the local structural characteristics and dimensions of a prototype model.     

鸭乙型肝炎病毒的致病性及致癌性研究──鸭乙型肝炎病毒表面抗原的纯化

应用氯化铭密度梯度离心技术，结合Ｄｏｔ－ＥＬＩＳＡ试验、￣（３２）Ｐ标记的鸭乙型肝炎病毒（ＤＨＢＶ）ＤＮＡ探针进行斑点杂交试验，从ＤＨＢＶ阳性的启东鸭血清中分离得到高纯度的ＤＨＢｓＡｇ颗粒，直径范围４０～６０ｎｍ，在ＣｓＣｌ溶液中的浮密度为１．１５ｋｇ／Ｌ，大多数呈１０ｎｍ厚的空心结构，形态不规则，近似球形，部分颗粒表面有凹陷结构，少数颗粒表面出现缺刻。以纯化的ＤＨＢｓＡｓ免疫新西兰大白兔，制备了高度特异性的兔抗ＤＨＢｓ血清及其纯化的兔抗ＤＨＢｓＩｇＧ。     

辊锻模具型槽表面轮廓的几何分析

通过对辊锻模与锻件的啮合运动分析及几何分析，发现锻件轮廓与型槽轮廓存在共轭曲线（或曲面）关系。文中导出了参数方程、三次样条拟合函数及几种典型锻件轮廓曲线对应的辊锻模具型槽。这些结果对于精确、高效设计辊锻模具具有重要意义。