射流器臭氧—水混合数值模拟及喉管优化

应用气液两相流动的双流体模型,数值模拟了射流器内臭氧—水的混合过程,得到了喉管内流场的参数分布,揭示了利用射流器进行臭氧—水混合的工作机理,为射流器结构参数优化设计和性能预测提供了有效手段。分析了最优喉管长度与面积比的关系,结果表明：最优喉管长度随着面积比的增大而增长,当面积比为2.25～6.25时,射流器的最佳喉管长度应在5.84～7.47d1之间。     

苹果片气体射流冲击干燥工艺的优化

采用一种新型的气体射流冲击干燥技术,对切片厚度6～8mm的苹果片进行了干燥试验研究。在喷嘴直径为16mm,喷嘴气流速度为16.8m/s的条件下,得出苹果片气体射流冲击干燥处理的最佳工艺参数为:喷嘴出口气体温度70℃,喷嘴与苹果片最佳距离120mm,干燥盒宽度为200mm,物料堆积高度为35mm。     

气体射流冲击干燥无核紫葡萄的数学模型

针对气体射流冲击干燥技术,试验研究了不同风温、风速和预处理下无核紫葡萄的4种薄层干燥模型。在对无核紫葡萄进行L9(34)正交干燥试验的基础上,通过试验数据分析,对不同风温下的干燥曲线进行模型比较,经拟合得出适合无核紫的数学模型为Page模型。     

不同混合比例对葛藤甘蔗稍混合青贮品质的影响

为开发利用葛藤和甘蔗梢,生产优质青贮,调制了6 种混合比例的葛藤与甘蔗梢混合青贮。6 种混合青贮是按葛藤:甘蔗梢（质量比）分别为10:0、9:1、8:2、7:3、6:4 和0:10 进行调制,分别表示为100K、9K1S、8K2S、7K3S、6K4S和100S。每个处理5 个重复,常温下贮存50 天后开封,测定化学成分和发酵品质。结果表明,甘蔗梢比例的升高能够提高葛藤甘蔗梢混合青贮的品质,随着甘蔗梢的比例升高（除100S）,青贮料的干物质含量、pH值和氨态氮含量呈降低的趋势,中性洗涤纤维含量、半纤维素含量、乳酸含量、乙酸含量和丙酸含量呈升高趋势。综合来看,6 种混合比例中,6K4S青贮料的pH值、氨态氮含量较低,粗蛋白含量和乳酸含量较高,青贮品质最佳。     

拖拉机作业速度的选择

拖拉机牵引农机具进行农田作业前进的速度,应根据土壤类别、地表状况、功率消耗的承担能力及各地的相应农艺要求来确定,有些新农机手对这方面的知识了解不多。为帮助农机手提高作业质量和充分发挥机车应有的生产效率,下面以有6个前进挡位,速度为1.4～15.3千米/小时的东风-12型手扶拖拉机为例,介绍拖拉机在农田作业中速度的选择,供农机手参考。     

棉籽吸水速度的研究

棉籽在不同的温、湿度条件下吸水,都有三个快速吸水阶段,随温、湿度提高吸水速度加快。经硫酸脱绒的棉籽和温汤浸种后又晾干的棉籽.在28～30℃、4～5℃温度条件下吸水,其吸水速度都快于干籽,吸胀过程快速完成,没有明显的快速吸水阶段。田间插种条件下,5厘米地温低于8～10℃,棉籽需5天吸水达萌动饱和含水量(75%～80%);温度高于12～14℃,2～3天即可达到。     

无公害蔬菜栽培肥料的科学混合施用

<正>在无公害蔬菜栽培中,菜农常把两种及两种以上的单元肥料和复合肥料混合使用或配合施用,这样不仅减少施肥次数、节约劳力,同时能给作物提供多种养分,达到提高肥效、作物增产提质、生态环保的效果。不过混用并不是简单随意地混合,只有科学合理混用才能达到预     

基于OH-PLIF技术的合成气燃烧速度

为了解合成气燃烧特性,采用高精度光学测量技术PLIF,研究了不同生物质气化合成气在不同当量比下的燃烧火焰结构、OH基浓度以及火焰传播速度。采用CHEMKIN软件模拟计算了相同工况下合成气火焰传播速度,对引起温度变化和OH基浓度变化的原因进行了化学动力学分析。研究结果表明,合成气中CO含量的增加会使火焰整体结构变小,但对内焰影响程度不大,而H₂含量的增加会增大火焰的传播速度。合成气燃烧过程中主要影响OH基生成的是R36：CO+OH=CO₂+H、R43：H+O₂+M=HO₂+M和R45：H+HO₂=2OH这3个基元反应。     

甲醇/柴油混合燃料的应用

在柴油机结构不变的情况下,把甲醇、柴油、OP乳化剂按体积比15:80:2.5混合,采取新的乳化工艺研制混合燃料,并与柴油作比较.甲醇.柴油混合燃料的密度和粘度较柴油降低,粘度为1.20°E20,雾化质量和蒸发性能得到提高.随着负荷的增大,柴油机燃用混合燃料的耗油率低于燃用柴油的油耗率,经济性有所提高.甲醇.柴油混合燃料平均节油率达9.5%,在中、高负荷下节油率平均达12.4%.在中、高负荷范围内燃用混合燃料的烟度均低于燃用柴油时的,下降达25.6%,NOx的排放值显著降低.柴油机燃用甲醇.柴油混合燃料热效率有所提高,中、高负荷时耗油率显著下降,经济性好,减少了环境污染,具有良好的经济和社会效益.     

蓝莓黑木耳混合果汁饮料的加工工艺研究

以蓝莓汁和黑木耳粉为主要原料制成混合果汁饮料,通过试验对其配方、稳定剂等工艺进行研究,结果表明最佳配方为蓝莓汁原浆稀释至100%后加入蔗糖含量15%,黑木耳粉含量1.0%,柠檬酸含量0.40%混合调配,得到最佳口感的混合果汁。采用卡拉胶含量0.07%,海藻酸钠含量0.25%,羟甲基纤维素钠（CMC-Na）含量0.15%作为复合稳定剂,均质条件为2次100 MPa,产品具有良好的稳定性、风味和口感。     

Effect of Main Parameters on Cutting of the Pulsed Abrasive Water Jet

The relationship between abrasive concentration, length of oscillating chamber, standoff distance and cutting depth, erosion rate as well as cutting specific energy was investigated by experiments in the submerge and surface conditions. The cutting and erosion capabilities of the pre-mixed abrasive water jet and the pulsed abrasive water jet were analyzed in contrast. It is shown that the maximum cutting depth and erosion rate of the pulsed abrasive water jet are respectively 1.67,1.72 and 1.39, 1.47 than the pre-mixed abrasive water jet in submerge and surface conditions. These results attained from the research are useful to increase the cutting efficiency, decrease the energy ratio and expand the application domains of the abrasive water jet.     

Experimental analysis of the abrasive belt follow-up grinding of Zirconium-4 alloys tubes and pipes

Abrasive belt grinding experiments of Zr-4 nuclear power tube are carried out by using three different abrasive belts with same size, and the interactive generating mechanism between abrasive and workpiece is analyzed, the main factors of material removal rate and surface roughness of Zr-4 alloys are obtained. With the help of the advanced test facilities, the abrasive grain abrasion and surface topography of the workpiece are observed. The metallographic structure and microhardness of the layer of burnt surface during Zr-4 alloys Grinding are analyzed. Some conclusions are given as follows: the material removal rate and surface roughness are mainly affected by the factors of belt speed, grinding pressure, hardness of the contact wheel and abrasive type, of which, the belt speed is the strongest factor. The adhesion wear of the Zirconium corundum and aluminium oxide abrasive grit is more serious, the most important wear form of silicon carbide is abrasion wear. With the onset of grinding burn, the mechanical properties of Zr-4 alloys are deteriorated obviously. The results provide a theoretical and experimental basis for technical optimization in the grinding of Zr-4 alloys with efficiency and high quality.     

Study on Hydrokinetics of the Unsubmerged Premixed Abrasive Water Jet

A mono-liquid model is established according to formative character of the premixed abrasive water jet. The hydraulic structure is analyzed by the model. The relationship that is obtained between the axial shaft line velocity and the forget distance by the law of conservation of momentum is verified with the experiment.     

植物蒸腾作用高速率之原因

摘要：植物蒸腾作用是植物最重要的生理活动之一,阐明植物蒸腾作用高速率的原因在农业方面有着重要意义。基于植物气孔结构,运用气象学、栽培学、高等数学、热学等学科相关理论,阐明了植物气孔蒸腾高速率的原因,即巨大的蒸发面积、较高的微环境温度、较大的气孔内外气压差等三因素,再此基础上,进一步阐明植物蒸腾作用高速率的原因,即叶面积指数和气孔下腔的特殊结构增大了蒸发面积、水分供应充足。气孔下腔有巨大的蒸发面积、较高的微环境温度、较大的气孔内外气压差、大的叶面积指数、充足的水分供应是植物蒸腾作用高速率的主要原因。     

Effects of Wave Speed on Frequencies of the Self excited Oscillation Pulsed Abrasive Water Jets

The effects of cavitation and abrasive acceleration in the self excited oscillation pulsed abrasive water jets are directly determined by its oscillating frequencies, so the wave speed in the jets and its effects on pulsed frequencies are discussed. The numerical results show that the oscillating frequencies of the jets increase obviously with decreasing wave speed, and the abrasive parameters have almost no effects on the wave speed, whereas the exit of air in fluid has significant consequences on the wave speed.It was found that these conclusions were applicable for design the nozzle of the jets.     

A novel keyframe extraction method based ondynamic time-domain detection windows

Real-time keyframe extraction is significant for the on-line video retrieval and recognition system. It will lead to low speed for keyframe extraction by analyzing the frames one by one on the basis of shots detection. A novel keyframes extraction method based on dynamic time-domain detection windows is presented. The video frame-sequence is divided into video units with different lengths. The frames at the edges of the window and the sampled frames inside the window are analyzed to judge the changes of the unit content. Meanwhile, a hybrid growth mode of windows and slow detection mechanism are proposed to ensure the quality and speed of the keyframe extraction. The extracted keyframes are clustered to obtain the best keyframe. The experiments show that the proposed method has a good comprehensive performance for different kinds of videos.     

机器学习在农作物品种识别中的应用研究进展

机器学习在图像识别领域的成功应用,为农作物品种的自动识别提供了一种新的思路。为了全面了解机器学习在农作物品种识别中的应用现状,把握农作物品种识别的发展趋势和研究方向,本文归纳了农作物图像的常用获取方法,分析了光谱图像和RGB图像结合机器学习方法识别农作物品种的研究现状。基于RGB图像进行农作物品种识别研究起步较早,图像获取成本较低,识别率一般;基于高光谱图像进行农作物品种识别研究近年来发展迅速,识别精度较高,但图像获取成本较高,且易受环境因素影响。通过总结,指出了农作物品种识别研究中存在的问题,认为深度学习在农作物品种自动识别上具有广泛的应用前景     

Investigation and application of jet aeration technology in the oxidation process of desulfurization slurry

The calcium sulfite oxidation rate is an important indicator to judge the efficiency of wet limestone/gypsum flue gas desulfurization process used by high-sulfur-coal power plant. Jet aeration technology which integrates aeration and stir into one apparatus is proposed to implement the forced oxidation of limestone/gypsum flue gas desulfurization in order to improve the oxidation rate. The working principle of jet aeration oxidation in desulfurization slurry is investigated. ANSYS CFX is used to simulate the flow field inside the desulfurization slurry tank and obtain the best installation method of jet aerator which makes the mixing and stirring effect of slurry ideal: 3 jet aerators are uniformly installed at the height of 0.8m up from the bottom of slurry tank with their axis perpendicular to the tank wall. The air suction flowrate of jet aerators is tested under the best installation method in the on-site application test of the X protection company of Chongqing. The oxidation rate of calcium sulfite in desulfurization slurry is also tested by using iodometric method. The results show that the total air suction flowrate of jet aerators is 59.52 m 3/h which meets the requirement of slurry oxidation air quantity and the oxidation rate of calcium sulfite in desulfurization slurry reaches 87.6% after two-hour oxidation by using jet aeration.