Drying characteristics, functional properties and in vitro digestion of purple potato slices dried by different methods

The drying characteristics,physico-chemical and functional properties,as well as starch digestibility,of purple potato slices dried using different methods(such as,vacuum freeze-drying,VFD;hot-air drying,HAD;air-impingement jet drying,AIJD;and far-infrared assisted heat-pump drying,FIHPD)were investigated.Drying rate was the highest(3.0 g 100 g^-1 min^-1)using AIJD,followed by FIHPD and HAD,and the rate of VFD was the lowest one(0.3 g 100 g^-1 min^-1).Drying data were fitted to 12 thin-layer drying models,with the Midilli model giving the best predictions.Moreover,AIJD showed higher diffusivity(5.5×10^-10 m^2 s^–1)and energy efficiency(55 J g^-1)than any other drying method used in this study.With reference to the samples dried by VFD,the starch granules of the samples obtained by HAD,FIHPD,and AIJD exhibited different extent of disruption,which significantly increased their water absorption capacity,swelling power,and in vitro digestibility,but decreased the peak viscosity.The sample resulting from AIJD had the greatest water absorption capacity(7.9 g g^-1)and solubility(21.6%),but the smallest syneresis rate(48%).Good correlation coefficients(R^2>0.98)implied that the pseudofirst order kinetic model adequately described the rate and extent of starch digestion of dried potato flours.Samples from AIJD and FIHPD showed the highest digestibility percentages,reaching to 72.4 and 72.5%.Based on the drying rate,specific energy consumption,functional properties and digestibility,AIJD appeared to be quite effective and suitable to be transferred on the industry scale.

Determination and Evaluation of Strength Characteristics of Dry Jet Mixing

Dry jet mixing (DJM) for soft soil stabilization has been widely used since 1980s. The quality and strength of stabilized columns are fundamental parameters to evaluate the stabilization work. This paper presents the standard penetration test (SPT) method and its test results on cement columns. It is shown that SPT is an effective and simple method for inspecting and evaluating cement columns. The strength characteristics along the length of the column, a good correction between SPT blow count and the unconfined compressive strength are achieved.

Modeling of workpiece temperature suppression in high-speed dry milling of UD-CF/PEEK considering heat partition and jet heat transfer

High-performance carbon fiber-reinforced polyether-ether-ketone(CF/PEEK)has been gradually applied in aerospace and automobile applications because of its high strength-to-weight ratio and impact resistance.The drymachining requirement tends to cause the cutting temperature to surpass the glass transition temperature(Tg),leading to poor surface quality,which is the bottleneck for dry milling of CF/PEEK.Temperature suppression has become an important breakthrough in the feasibility of high-speed dry(HSD)milling of CF/PEEK.However,heat partitioning and jet heat transfer mechanisms pose strong challenges for temperature suppression analytical modeling.To address this gap,an innovative temperature suppression analytical model based on heat partitioning and jet heat transfer mechanisms is first developed for suppressing workpiece temperature via the first-time implementation of an air jet cooling process in the HSD milling of UD-CF/PEEK.Then,verification experiments of the HSD milling of UD-CF/PEEK with four fiber orientations are performed for dry and air jet cooling conditions.The chip morphologies are characterized to reveal the formation mechanism and heat-carrying capacity of the chip.The milling force model can obtain the force coefficients and the total cutting heat.The workpiece temperature increase model is validated to elucidate the machined surface temperature evolution and heat partition characteristics.On this basis,an analytical model is verified to predict the workpiece temperature of air jet cooling HSD milled with UD-CF/PEEK with a prediction accuracy greater than 90%.Compared with those under dry conditions,the machined surface temperatures for the four fiber orientations decreased by 30%–50%and were suppressed within the Tg range under air jet cooling conditions,resulting in better surface quality.This work describes a feasible process for the HSD milling of CF/PEEK.

蒸气喷射真空干燥技术及其设备的研究

蒸气喷射真空干燥技术和设备 ,以其投资少 ,效率高 ,能耗低 ,产品质优价廉 ,使用潜力大、范围宽 ,设备结构简单 ,工作性能可靠等优点 ,获得了良好的推广应用价值和广阔的发展前景。

THE DYNAMICAL ANALYSIS OF THE STRUCTURE OF Β MESO-SCALE DOUBLE RAINBANDS IN MEIYU FRONT

In this paper, an idealized perturbation following the ＂surge-flow conceptual model＂ for typical Meiyu frontal structure is designed to explain the β meso-scale structure ofrainbands in the Meiyu front using a non-hydrostatic, full-compressible storm-scale model including multi-phase microphysical parameterization. In addition, sensitivity numerical experiment on the vertical distribution of the ambient meridional wind is conducted to investigate the generation mechanism of D meso-scale double rainbands. The results of numerical experiments show that the cool and dry downdraft invading strengthened by the environmental aloft northerly wind plays a very important role to the generation and maintenance of the β meso-scale double rainbands. Moreover, the intensity and scale of the dry and cool downdraft invading are related to the intensity of the second circumfluence induced by mass adjustment when the acceleration of the westerly jet aloft occurs.

Economic Study of the Wind Energy Potential in Sahel

The wind pattern in Sahel is marked by a strong diurnal cycle as well as a strong seasonal cycle. The low level jet is blowing above the near-surface layer during nighttime and is decoupled from the surface. Nowadays, some studies showed the possibility to use the sub-jet wind at levels higher than 90 m as a source of energy in this area. In the present work, the wind turbines, with hub heights situated at 150 m and blade extremities at 150 ± 60 m, were used to make an economic study of wind energy potential in Sahel. Thus, monthly wind power was determined by two methods. The first involved the wind distributions directly observed. The second was based on the Weibull distributions which were fitted to the data. Day and night were compared. Results showed that this jet was an attractive source of energy provided if huge-capacity energy storage was used. So, the energy stored at night could be restored during the daytime, when the demand is highest. An economic study was done to estimate the number of wind turbines needed to satisfy the Niamey demand. The cost was found reasonably cheap relative to that of other renewable energy sources.