高寒地区农田栽培西洋参的试验研究

研究北方农田退化黑钙土经过改土施肥处理，对西洋参生长发育的影响。试验结果表明，黑钙土壤中掺２０％草炭灰西洋参根系增长２％，增粗２２％，增重４５％。施混合畜肥体根系增长１８％，增粗３９％，增重４５％。每ｈｍ２（公顷）平均产鲜参１２５０～１５０００ｋｇ。

Exploiting Additive Manufacturing Infill in Topology Optimization for Improved Buckling Load

Additive manufacturing （AM） permits the fabrication of functionally optimized components with high geometrical complexity. The opportunity of using porous infill as an integrated part of the manufactur- ing process is an example of a unique AM feature. Automated design methods are still incapable of fully exploiting this design freedom. In this work, we show how the so-called coating approach to topology optimization provides a means for designing infill-based components that possess a strongly improved buckling load and, as a result, improved structural stability. The suggested approach thereby addresses an important inadequacy of the standard minimum compliance topology optimization approach, in which buckling is rarely accounted for; rather, a satisfactory buckling load is usually assured through a post-processing step that may lead to sub-optimal components. The present work compares the stan- dard and coating approaches to topology optimization for the MBB beam benchmark case. The opti- mized structures are additively manufactured using a filamentary technique. This experimental study validates the numerical model used in the coating approach. Depending on the properties of the infill material, the buckling load may be more than four times higher than that of solid structures optimized under the same conditions.

An Experimental Study on the Response of Model Footings Resting on Reinforced Flyash Beds under Repeated Load

In the present, investigation an attempt has been made to study the behavior of reinforced flyash beds under repeated loads by conducting carefully designed experiments. The main objective of the experiments conducted is to evaluate the beneficial effects of using flyash as a backfill material in the reinforced beds to resist the repeated loads. As no unique standard equipment is available for the application of repeated loads and to measure the response, different researchers have designed and fabricated different types of equipments for the testing. The repeated load of known intensity with waveform type and frequency is applied on the surface and embedded footing in unreinforced and reinforced flyash beds. The response of the flyash beds, in the form of settlement is measured using linear variable differential transducers. The experimental results clearly demonstrated that the provision of reinforcement in the flyash beds is effective in improving the performance of both surface and embedded footing under repeated loads.

Gas-Liquid Two-Phase Axial Backmixing Through Structured Packing at Elevated Pressure

An experimental study of the extent of axial backmixing in both gas and liquid phases was conducted in a 150 mm ID column packed with Mellapak 250Y corrugated structured packing. The column was operated at pressures ranging from 0.3 MPa to 2.0MPa with nitrogen and water flowing countercurrently through the packing. The amount of axial backmixing was experimentally evaluated by the pulse response techniques using hydrogen in gas phase and an aqueous solution of NaCl in liquid phase as inert tracers. The response of the tracer was monitored by means of thermal conductivity in the gas phase and electrical conductance in the liquid phase. The experimentally determined residence time distribution (RTD) curves were interpreted in terms of the diffusion-type modei. The results indicated that the axial backmixing in the gas increased notably with gas flowrate and slightly with operating pressure and liquid flowrate. The liquid-phase axial backmixing was an increasing function of both gas and liquid flowrates and insensitive to pressure. Various correlations were developed for reproducing the experimental mixing data. The agreement between experimental and correlated data appeared to be acceptable and within ±20% of difference.

Liquid Axial Mixing in Packed Tower at Elevated Pressure

Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m, in which the structured packing, Mellapak 350Y, was installed. Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa. The model parameters of Bo and 9 were estimated with the least square method in the time domain. As liquid flow rate was increased, the liquid axial mixing decreased. Under our experimental conditions, the effect of pressure on Bo number on single liquid phase was negligible, and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil

The use of marginal backfills in GSE （geosynthetic stabilized earth） walls has not been recommended by different standards specifications. Restrictions are motivated by the poor hydraulic conductivity of fine soils that are capable of developing of water pressures. However, the use of granular materials can expend the cost of the construction. As a result, local soils, granular or not, have been increasingly used. Unsaturated conditions of fine soils may result in convenient performance even using extensible reinforcements. This paper evaluates the performance of a full scale model of a nonwoven geotextile reinforced wall constructed with fine grained soil backfill. The unsaturated condition was maintained and matric suctions, displacements and reinforcement strains were monitored during the test. Results have shown that the unsaturated condition of the backfill allowed maximum reinforcement peak strain of 0.4 %. For the case of a wrap faced wall on a firm foundation the performance and good agreement between measured strains and factors of safety from limit equilibrium analyses have shown the maintenance of unsaturated conditions as an economical alternative to the use of high quality fill.