GY8果园喷雾机喷雾特性研究

研究了GY8果园喷雾机的喷雾压力、测点位置、风机转速对雾滴粒径的影响,以及冠层位置、喷雾机行驶速度对雾滴覆盖率和穿透性的影响.结果表明:喷雾压力和测点位置是影响雾滴粒径的主要因素,果树高度、树冠密实度和喷雾机行驶速度是影响雾滴覆盖率和穿透性的主要因素.雾滴粒径随喷雾压力增大而减小,雾滴在风力输送过程中,雾滴过大易沉降,过细则易飘失,但在2～3m距离内雾流稳定,且雾滴粒径D50(体积中径)在200 μm左右,风机转速对雾滴粒径影响很小.各冠层位置的叶片背向覆盖率均远小于面向覆盖率.对于树形较大的果树,雾滴覆盖率随冠层高度增加而减小,各层分布很不均匀;对于树高小于3 m的果树,各层分布均匀且覆盖率较高.3种果树不同垂直层面雾滴覆盖率均随喷雾深度增加而减小.雾滴覆盖率随喷雾机行驶速度增加而减小,行驶速度增加1倍时,不同冠层高度和冠层不同垂直层面覆盖率分别平均减小31.8％和44.3％;当喷雾机行驶速度为0.5 m/s时,雾滴具有更好的穿透性,果树可获得更大的雾滴覆盖率.     

基于高速风洞的3种航空喷头雾化效果评价分析

通过高速风洞测试系统,模拟飞行时产生的高速气流,开展了气流大小和喷头结构参数对雾滴粒径及其分布的影响研究.研究结果表明:在喷头型号一定的情况下,3种航空喷头产生的雾滴粒径都随着风速的增大而减小;在喷雾压力一定、同一风速条件下,雾滴粒径均随着孔径的增大而增大;风洞条件下,3种航空喷头的雾滴谱相对宽度均较小,表明雾滴分布较均匀;空拖CP-03喷头结构多样,可以灵活调节流量,用于不同条件的农药喷洒作业;相比其他喷头,GP-81A喷头流量大,雾滴粒径较大,应结合飞机作业参数进一步优化喷头结构,以实现低量喷雾,减少农药浪费;直升机旋流喷头结构单一,需要根据直升机喷雾特点对雾化装置做进一步优化改进.     

南京高塔风洞模拟研究

籍流体力学风洞,取截段模型,对南京八卦洲气象观测高塔作风洞模拟实验,测定了模型塔周围和尾迹区的平均流场和脉动场。实验结果表明:在塔后部大约72°的扇形区范围,存在一个风速亏损区和湍流度分布无规区。当塔的伸臂长度L=1.0D时,此范围内风速亏损可达25％,并且风速亏损愈大,湍流度亦大。在其余288°方位,测量值与风洞来流值基本一致。在塔后尾迹区的塔柱后侧,风速亏损和湍流度均出现极大;它们还随着与塔柱的距离的增大而减小。     

不同雾化条件下静电喷雾沉积效果研究

以静电涂油机中的新型静电喷雾装置为研究对象,采用数值仿真技术来模拟雾滴在不同雾化条件下对目标喷涂物的喷雾轨迹,分析雾滴粒径、荷质比以及喷射间距对静电喷雾沉积效果的影响.结果表明,雾滴粒径相同时,随着雾滴荷质比的增加,雾滴沉积效果明显改善,但同时雾滴跑偏的情况也会增加;在喷射间距和雾滴表面电荷密度一定的情况下,大粒径雾滴的沉积效果较好,小粒径雾滴容易跑偏;对于粒径和荷质比相同的雾滴,喷射间距较大时喷雾沉积效果较差.     

前掠翼模型低速气动力实验与仿真

基于一种高速前掠翼布局翼身组合体缩比模型,开展低速风洞纵向气动力实验研究,包括与相应后掠翼对比实验和细长边条前掠翼实验,实验攻角-4°～+36°,特征雷诺数4×10₅。结果表明：低速实验条件下,前掠翼升阻力特性与相应后掠翼基本相同,但前掠翼表现出良好大迎角气动性能发展趋势。翼根前加装面积仅为机翼面积5.2%的大后掠细长边条后,前掠翼升力特性明显改善,33°迎角时最大升力系数比基本前掠翼提高约40%。依据模型风洞实验实际条件,采用雷诺时均方程和FLUENT软件,进行前掠翼模型流场气动力数值仿真,仿真计算模型构建合理,能够支持分析风洞实验数据。     

衍射仪精确测定晶格常数的误差分析及处理

讨论了测角仪0°位置及焦点180°位置的调整方法以及检查调整质量的简便办法;论证了增加制样时的压力,调整样品的密度分布,既可减少因x射线的穿透性而引起的误差,又可改善平板试样的聚焦条件;绘制了Y-2A型衍射仪工作时内部温度升高而引起的0°位置及衍射峰角位置漂移规律的实验曲线,为精密测量结果的修正提供了依据。     

跨声速风洞翼型动态失速实验系统研制

为满足旋翼设计的需要,研制了增压连续式跨声速风洞二元试验段翼型动态失速实验系统。开发了相应的测控系统,设计并安装了机械驱动机构,建立了数据采集及其后处理系统。动态试验测控系统的测量部分与控制部分相互独立,且与风洞主控系统、安全联锁系统等互不影响,可单独工作,安全性高,抗干扰性能好。机械系统设计合理,运动轨迹精确,该机构以平均迎角0°振幅10°,振荡频率2Hz运行时,最大迎角误差为±0.809°,平均迎角误差为0.255°,振幅均方根误差为0.325°,满足翼型动态失速实验的要求。数据采集采用多路并行A/D,其同步性能好,避免相差。在风洞实验系统联调中使用了NACA0012翼型模型,通过在翼型表面安装动态压力传感器,测量Ma=0.3,平均迎角为10°, 振幅为5°,减缩频率分别为0.05,0.03和0.01下,翼型表面脉动压力。其结果表明,实验系统在大动压,不同频率下,运行稳定,数据合理可靠,实现了设计要求。     

涡轮叶栅叶顶间隙泄漏流动实验研究

针对一种高负荷涡轮叶栅,利用低速矩形叶栅风洞实验研究叶顶间隙泄漏流动．研究了不同叶顶间隙和不同来流冲角情况下,涡轮叶栅的流场结构和气动性能．研究工况包括无间隙,0.5%、1.0%、1.5%叶高间隙和±10°、±5°、0°冲角．通过五孔探针获得矩形叶栅出口截面上总压、气流角以及速度分布;通过叶片表面开设的静压孔,获得叶片中部以及靠近叶顶截面的叶片表面静压分布．实验结果表明:叶顶间隙的存在增强了叶栅顶部的二次流动,恶化了上半叶展的流动状况,涡系结构发生了改变．随着叶顶间隙的增大,叶栅总压损失增加,气流偏转不足/过偏现象加剧;随着冲角的增大叶栅总压损失增加．     

风送荷电喷雾特性试验

为研究风送荷电喷雾在空间的粒径分布和沉积特性,设计了一种风送荷电喷雾试验装置,包括雾化装置、荷电装置、风送设备以及相应的测量设备.首先对轴流风机改造前后的气流速度进行了对比,然后探讨了雾滴的荷质比和云电流与电压的关系,最后研究了荷电与非荷电状态下,喷嘴轴线上的雾滴粒径和沉积质量的分布规律,以及轴线上距喷嘴出口2.0和3.0 m,沉积质量沿水平径向(y方向)和雾滴粒径沿垂直径向(z方向)的分布特点.研究结果表明:改造后的轴流风机产生的气流轴向速度增大,有助于增加喷雾射程;雾滴的荷质比与云电流随电压的升高而增大;荷电与非荷电情况下,雾滴粒径与沉积质量均随轴向距离的增加先增大后减小,呈现单峰分布;荷电雾滴沿垂直径向的粒径分布关于轴线呈现出较大的不对称性,即小雾滴在轴线上方,大雾滴在轴线下方;荷电雾滴沿轴向(x方向)和水平径向(y方向)的沉积范围较广且均匀性较好.     

流体攻角对滴形钉头管流体阻力特性的影响

利用风洞实验 ,研究了Re =1× 10 4～ 1× 10 5范围内滴形钉头管在不同攻角下的流阻特性 .实验结果表明 ,攻角对滴形钉头管的流阻特性影响显著 ,流阻最小值出现在攻角α为 180°时 ,最大值出现在攻角α为10 0°～ 110°时 .还给出了不同攻角下Eu与Re之间的关联式 .     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with