溴氟菊酯等几种农药防治害虫的药效试验

通过1990－1993年的小区试验和大田示范说明上海中西药业公司新研制的拟除虫菊酯农药溴氟菊酯，是一种广谱性的杀虫杀螨剂，其药效与三氟氯氰菊酯，甲氰菊酯相似，优于常用农药久效磷，氧乐果和三氯杀螨醇，10％溴氟菊酯在1000－1500倍浓度下，对蚜虫，叶螨，棉铃虫和地老虎等害虫的防效，喷药后10天均在95％以上，且初效快，药效可长达15天左右。     

Using a coupled CFD – DPM approach to predict particle settling in a horizontal air stream

Preventing health and safety hazards such as dust explosions and respiratory exposure in the work force when handling and storing fine powders is a major challenge faced by plant operators [13]. Computational Fluid Dynamics (CFD) coupled with Discrete Phase Model (DPM) can be used as a tool to address this challenge by advancing the understanding of how particles deposit in a particular process. Particle settling, in air streams, is primarily dependent on the drag forces exerted on the individual particles through interactions with the suspension medium [2]. By improving the understanding of this interaction through repeatable experiments and simulations; more complex CFD – DPM simulations are possible, thus providing a significant step in reducing the risks associated with handling fine powders. To study the transport and settling of particles in air streams, an experiment was established where glass beads, alumina and iron ore dust were injected into a horizontal flow channel. The material was fed into the top of the test rig where it was then transported in a laminar air stream. Through this method particle settling, according to the particle size, can be observed by sampling different trays along the bottom of the test rig. Once the deposition of particles is analysed (using a particle size analyser) each diameter range can be tracked to determine the distance travelled. After evaluating these experiments a CFD coupled with DPM simulation was employed to predict particle deposition in the horizontal chamber. The results show a good agreement between experiments and CFD – DPM results.     

Lantern-Inspired On-Skin Helical Interconnects for Epidermal Electronic Sensors

Epidermal electronics have been attracting considerable attention due to their various potential applications in human-computer interaction and health monitoring. However, because of the lack of a self-adhesive and stable interconnect method between epidermal electronic sensors and rigid circuit boards, there remain difficulties in detecting body signals accurately by epidermal electronic sensors in daily life. Here, a 3D helical on-skin interconnect is first introduced for epidermal electronics sensors. Inspired by the structure of the accordion lantern, the interconnect is composed of two electrospinning polyurethane (PU) fiber films and a helical metal fiber. The helical metal fiber acts as a stable conductor with stretchability, and the PU fiber film with polydimethylsiloxane provides a self-adhesive substrate. Mechanical simulations and tests prove that the proposed interconnect can laminate conformally and unobtrusively onto human skin with excellent electrical stability (less than 0.5% electrical resistance change upon 100% elongation). Furthermore, based on the proposed interconnect, an all-in-one sensor-interconnect design is presented, which endows the epidermal electronic systems with anti-motion interference capability. A gesture identification wristband system realized by a single all-in-one strain sensor is demonstrated. Besides, a wireless on-skin system that accurately monitors dynamic 12-lead electrocardiographic is successfully built using all-in-one electrodes.     

Change in the characteristics of the industrial powder of zirconium oxide and materials based on it by mechanochemical activation

The influence of the mechanochemical activation (MCA) of zirconium dioxide industrial powder partially stabilized with yttrium oxide and properties of materials based on it are investigated. It is shown that the MCA in an aqueous medium with the addition of agar allows one to obtain an ultradispersed powder with a particle size approaching the nanometer range. The sintering temperature of the articles from this powder is only 100°C higher than for nanocrystalline powders. As the activation time increases (≥10 h), it is possible to detect the milling of silicon dioxide from the lining of the planetary mill by IR spectroscopy. The largest strength is noted for the samples made of the powder activated over 10 h. An increase in the silicon dioxide content leads to a decrease in the material strength. To effectively activate the zirconium dioxide powder without varying the powder composition, 2.5 h is sufficient.     

振动水嘴流场的大涡模拟

基于井下采油需要,于注水驱油装置内适当位置设计了亥姆霍兹振动水嘴进行脉动注水,以增强注水效果.本文从数值模拟角度出发,采用大涡模拟(Large Eddy Simulation-LES)方法数值预测了振动水嘴流场,得到了流场速度和压力分布,结果表明不同尺寸亥氏水嘴,自激振动效果差异很大,对固定的来流条件,存在着最佳的尺寸组合.通过水嘴出口平均压力实验测量与文中数值模拟的对比,表明数值预测方法正确、计算格式稳定、结果合理及有关程序应用方便,可与实验研究互相配合,促进自振水嘴机理和实用研究.     

Theoretical and experimental testing of a scaling rule for air current segregation of alumina powder in cylindrical silos

Air current segregation (ACS) is one segregation phenomenon that has been identified to contribute significantly to the separation of fines (particles < 42 µm) from coarse material during the filling of industrial silos. This paper describes investigations of ACS for alumina powder based on experiments conducted in an industrial silo, in the laboratory and by computation, using the commercial computational fluid dynamics code Fluent.For the industrial silo, the extent of ACS has been measured using the accumulation of fine material at the wall as an indicator. Based on these results, modifications to the feeding system were undertaken which showed that ACS is promoted if the material is fed in a dilute form. Experiments in the laboratory confirmed this effect visually. In order to be able to compare numerically the extend of ACS, a segregation index has been developed. It was found that a dilute particle jet leads to more ACS than dense particle jet.The effects of solids feeding rate and air extraction rate on ACS have been investigated in the laboratory silo and the results clearly show that low solids feeding rates promote ACS. It was further found that an increase in the air extraction rate has a mild effect in suppressing ACS. These effects were confirmed by the Fluent simulations, which showed an unexpectedly good agreement with the experiments.     

Yield Strength Enhancement Without Ductility Loss Through Controlling the Intercritical Annealing Time in Medium-Mn Steels

Herein, the effect of shortening the intercritical annealing (IA) time in a two-step process “intercritical annealing and tempering (IAT)” on the microstructure and the mechanical properties of medium-manganese steel (MMnS) made of Fe–0.05C–7Mn–1.5Cu–1.5Ni–1.5Al–1.5Si–0.5Mo (wt%) and containing copper-rich (CRP) and Ni(Al/Mn) precipitates is investigated. The atom probe tomography (APT), electron backscattering diffraction (EBSD), and the synchrotron X-ray diffraction (SYXRD) are used to study precipitation, phase microstructure evolution, the austenite stability, and deformation mechanisms. Shortening the IA step, which is carried out at 700 °C, from 2 min (IAT-2) to 1 min (IAT-1), results in a yield strength (YS) increment of around 218 MPa with less than 1% loss of ductility. While the enhanced yield strength in IAT-1 is attributed to the four times higher precipitates’ number density (n), the insignificant loss of ductility is attributed to the enhanced austenite stability factor from 4.5 to 9.2 in IAT-2 and IAT-1, respectively. The simultaneous increase in YS without ductility loss reflects that controlling the IA time is a promising strategy to overcome the yield strength and ductility trade-off without the need for higher additions of costly alloying elements such as Ni, Al, Mn, and Cu.