一种基于三棱柱的三维地质体可视化方法研究

提出了一种用三棱柱作为基本体元来实现三维地质体可视化的方法．该方法首先将原始的钻孔数据经过预处理形成各个地层上下对应的网格高程数据，然后连接相邻地层上下对应的网格形成四棱柱，将四棱柱沿网格对角线分开，形成三棱柱基本体元．根据笔提出的三棱柱数据结构，把三棱柱剖分的情况分为完全剖分、特殊剖分和伪剖分3大类，并给出了3类剖分的特点以及各自包含的三棱柱剖分和重组方法．应用该方法对淮南某矿的地质体进行了可视化研究，结果表明该方法是切实可行的．     

基于流量工程的分割控制算法的分析与研究

对 IP网络中的流量工程机制及其流量分割控制算法进行了讨论与研究 ,介绍了流量工程的含义 ,并分析相关的优化算法 ,在指出其难点的同时 ,提出了一种新型的流量分割控制算法 ,并对该算法作了深入细致的分析与研究。结果表明 ,该算法是具有可实现性的。     

基于双压驱动的恒流斩波系统的设计

恒流斩波电路中，步进电机的驱动电压高，绕组回路阻抗低，电流上升较快。单一的恒流驱动电路在低频时绕组电流上升过快，容易导致低频过冲振荡现象。为避免振荡，本文采用双压驱动与恒流斩波驱动相结合：低速运行时采用低电压供电，低频过冲振荡小，转动平稳；高速运行时采用高电压供电，高频输出扭矩大，不易堵转。     

Curve interpolation with variable feedrate for surface requirement

Finish machining of a curved surface is often carried out by an NC system with curve interpolation in the field. This function, called a NURBS interpolation, adopts a feedrate optimizing strategy based on both the geometrical information of the curved path and dynamic properties such as the curvature of the curve, the allowable acceleration and the time constant. However, in the case of a finish cut using a ball-end mill, the curve interpolator needs to take the machining process into account for improved surface roughness, while reducing the polishing time. This surface roughness on high-speed machining is theoretically defined by the feed per tooth and the pickfeed at the given radius of the tool. In this study, the effect of low machinability at the bottom of a tool on surface roughness is also considered. A curve interpolation algorithm is proposed for generating particular feedrate commands that are able to control the roughness of a curved surface. The simulation of the machined surface by the proposed algorithm was carried out, and experimental results are presented. A feedrate scheme that depends on the inclination angle has important potential application in part finishes consistent with prescribed surface roughness. The results show that the proposed algorithm is potentially useful for roughness-controlled machining of curved surface products.     

振动切削在螺纹加工中的应用

针对应用日益广泛的难加工材料的攻丝难题,根据振动切削基本原理,研制出具有振动攻丝功能的激振装置,并对其进行理论研究和实验分析,结果表明:振动攻丝切削力呈现出明显波形,攻丝扭矩的均值大大低于普通攻丝.     

梅钢1#连铸机优化切割模型的二次开发

随着产品订单逐渐小量化,质量要求越来越高,客观上要求切割长度的控制精度、优化策略逐步提高,以便最大限度地切成正常板坯,提高钢水的成坯率。为提高铸坯的定尺符合率,梅钢重新开发优化切割模型,并成功上线运行。     

Commiphora myrrha (Nees) Engl. extracts: evaluation of antioxidant and antiproliferative activity and their ability to reduce microbial growth on fresh‐cut salad

With the aim to develop natural preservatives displaying also chemopreventive activity, different Commiphora myrrha (Nees) Engl. extracts were studied. Myrrh essential oils, obtained by steam distillation and microwave‐assisted hydrodistillation, and several other extracts, obtained by sequential procedures with petroleum ether (PE), ethanol, ethyl acetate and butanol, have been screened for their antioxidant (DPPH· scavenging assay) and antiproliferative activity (on both nontumour and colon cancer cell lines) without previous purification. Considering that the colon cancer cell lines were more sensitive to PE and ethanol extracts, the latter of which showed the highest antioxidant activity (EC50 = 0.160 ± 0.008 mg mL^?1), both have been selected for further antibacterial/antifungal activity tests using an antimicrobial diffusion test and a growth inhibition test on salads. Results showed that the ethanol extract possessed the higher antibacterial and antifungal activity. Compared to untreated product, fresh‐cut salads treated with these two myrrh extracts displayed a significant lower bacterial growth. Although further investigation is required, these promising results offer hints as how to improve the shelf life of fresh‐cut salad.     

A pure proactive scheduling algorithm for multiple earth observation satellites under uncertainties of clouds

Most earth observation satellites (EOSs) are equipped with optical sensors, which cannot see through clouds. Hence, observations are significantly affected and blocked by clouds. In this work, with the inspiration of the notion of a forbidden sequence, we propose a novel assignment formulation for EOS scheduling. Considering the uncertainties of clouds, we formulate the cloud coverage for observations as stochastic events, and extend the assignment formulation to a chance constraint programming (CCP) model. To solve the problem, we suggest a sample approximation (SA) method, which transforms the CCP model into an integer linear programming (ILP) model. Subsequently, a branch and cut (B&C) algorithm based on lazy constraint generation is developed to solve the ILP model. Finally, we conduct a lot of simulation experiments to verify the effectiveness and efficiency of our proposed formulation and algorithm.     

Maintenance of postharvest quality and bioactive compounds of fresh‐cut sweet leaf bush (Sauropus androgynus L. Merr.) through hot CaCl2 dips

The effects of hot CaCl₂ dips on postharvest quality and bioactive compounds of fresh‐cut sweet leaf bush were investigated. The vegetable was dipped in 0.5% or 1.0% (w/v) of CaCl₂ solutions at 40 °C for 30 s and the control was the untreated sample. Hot CaCl₂ dips significantly delayed the weight loss, maintained the overall quality and inhibited the wiltness (P < 0.05). Both hot CaCl₂ dips had no effect on the changes in lightness (L*) and delayed the decrease in greenness (‐a*) and total chlorophyll content and the increase in both yellowness (b*) and carotenoid content. Hot CaCl₂ dips enhanced total antioxidants, total phenolics content and both AsA‐POD and G‐POD activities from 38.6, 0.44, 15.2 and 22.4 at day 0 to 55.3, 0.55, 50.5 and 362.4 at day 8, respectively. Moreover, hot CaCl₂ dips also delayed the loss of DPPH free radical scavenging activity, total flavonoid, ascorbic acid and CAT activity when compared to other treatments during storage. This study showed that hot CaCl₂ dip maintains postharvest quality and enhanced bioactive compounds of fresh‐cut sweet leaf bush during storage.     

Shelf life of ready‐to‐cook cauliflower mixtures as affected by packaging film mass transport properties

In this work, the influence of packaging mass transport properties on quality loss of fresh‐cut cauliflower mixtures was addressed. The study was organised in two subsequent experimental steps; first, the selection of micro‐perforated packaging films was carried out by monitoring the package headspace gas concentrations of fresh‐cut white, green cauliflower and roman cabbage. Then, the effects of the barrier properties of the selected micro‐perforated film on shelf life of two different fresh‐cut cauliflower mixtures, stored at 4 ± 1 °C, were addressed. Results suggested that, among the investigated films, the micro‐perforated polymeric matrix with the lowest oxygen transmission rate value showed the best performance as it created the optimum headspace gas composition for each cauliflower variety, as well as, for the product mixtures. The appearance of visible moulds was the factor limiting product shelf life that accounted for about 18 days for both the investigated cauliflower mixtures.