大曲发酵过程的环境温湿度均匀性调控系统研究

传统曲房在大曲发酵过程中受曲房空间、堆曲并房的影响,不同位置之间存在较大的温湿度差,最大温差可达22.90℃,最大湿度差可达41.40%相对湿度(relative humidity,RH),严重影响大曲的质量和一致性。T-S模糊神经网络控制具有响应速度快、超调量小等特点,能有效解决温湿度调节延迟的问题,从而使曲房内各区域温湿度保持均匀。因此,该文提出了将T-S模糊神经网络控制与曲房控制系统相结合的方法来调控曲房温湿度。搭建曲房的硬件与软件系统,设计T-S模糊神经网络控制器,并利用粒子群算法优化该控制器的参数,对控制器进行仿真和运用控制系统进行实际测试。结果表明,该控制器工作稳定,频率响应快;控制系统能够对曲房的温湿度进行实时测控,使发酵过程中不同发酵部位之间的最大温度差降低至6.30℃,最大湿度差降低至8.69%RH。通过该控制系统实现了大曲发酵过程中曲房内部各区域温湿度保持均匀,保证了大曲质量的一致性。

注射成型中的熔体温度均匀性研究

注射成型中的熔体温度均匀性直接影响注射制品的最终质量。熔体温度均匀性的大小与螺杆设计、加工工艺条件关系密切。对不同工艺条件和螺杆几何参数时的轴向温差进行了测量 。

螺杆构型对于注塑成型中熔体温度均匀性的影响

螺杆构型与熔体温度均匀性关系密切,注射成型中的熔体温度均匀性直接影响注射制品的最终质量。通过注塑机塑化系统软件IMP模拟通用型螺杆、屏障型螺杆、分离型螺杆的轴向和径向温度分布,并对其进行对比,得出屏障型和分离型螺杆温度均匀性更好,更适合精度较高的注塑成型结论。

浅谈料垛码法对倒焰式燃气窑内气流分布及温度均匀性的影响

通过料垛码法形成的气流通道大小对倒焰式燃气窑内气流分布以及温度均匀性的影响进行了分析,认为在一定的条件下,通道大小与气体流动速度和流量成正比,根据这一结论,可对倒焰燃气窑内料垛码法起到一定的指导作用。

探测器响应度不均匀性对测量LED平均发光强度的影响

使用响应度分布不均匀的探测器来测量光分布不均匀LED的平均发光强度时，其测量结果可能会引入显著的测量误差。设计实验装置对3种不同类型的探测器的响应度分布进行测量，结果表明带光漫射器的光度探测器响应度均匀性很差，这样的光度探测器用于测量一种白光LED平均发光强度时，响应度不均匀引起的测量误差可达2．0％。类似于光谱失配修正方法，给出了对探测器响应度不均匀性评价的方法以及响应度不均匀性评价因子C的表达式，并建议在进行LED平均发光强度测量时，应避免使用带光漫射器的光度探测器。

生物多样性和均匀度显著性的统计检验及网络计算软件

Shaanon-Wiener多样性指数和均匀度以其简单易用而被广泛应用于生物多样性和群落生态学等研究中。然而,由于缺乏适合的统计检验等原因,其分析的可信性较低。本研究以Shaanon-Wiener指数和Ewens- Caswell检验为基础,研制了生物多样性和均匀度显著性统计检验的Internet计算软件EwensCaswellTest。该软件由4个Java类和一个HTML文件组成,可运行于多种网络浏览器上。用EwensCaswellTest对水稻田节肢动物群落多样性(15个地点,17个功能群),以及中国民族HLA-DQB1等位基因的多态性(12个民族和人群,17个等位基因)进行了分析。结果显示,该检验可有效地反映多样性和均匀度的显著性。

中间坯加热参数对无磁钻具用钢晶粒度均匀性的影响

无磁钻具用钢为200系奥氏体不锈钢,其高强度特性要求是通过强化变形得到,无需热处理,导致该产品热锻后的晶粒均匀性较差,不能满足晶粒度级差在2级以内的要求。通过在无磁钻具产品强化变形前增加中间坯加热工序,研究了中间坯加热温度和时间对无磁钻具用钢晶粒均匀性的影响。结果表明,强化变形前中间坯经1100℃加热2~6 h,晶粒度的级别和均匀性均较理想,晶粒度在3级以上,级差在2级以内。中间坯加热温度过高时虽然会使晶粒度更均匀,但会导致晶粒相互吞噬趋势加剧造成晶粒粗大,加热温度过低则形核及静态再结晶能量不足,达不到晶粒均匀性的目的。

凹模内腔等离子体离子注入数值仿真—(Ⅰ)脉冲宽度效应

模具表面改性日益受到人们重视。本文采用二维Particle-in-cell/Monte Carlo Collision模型对等离子体浸没离子注入处理凹模型腔内表面的鞘层动力学及均匀性进行了研究。考察了电压脉宽对鞘层中电势分布、离子的运动状态以及型腔内表面离子注入剂量、能量和角度的空间分布的影响。结果表明随着电压脉宽的增加,凹模型腔内表面的注入剂量不均匀性增加,同时注入到内表面的高能离子数目也增加。脉冲宽度变化对注入角度影响不大,离子以接近垂直的入射角度注入到型腔底部,而在侧壁上离子注入角度接近45°。当脉冲宽度较大时,发现少部分注入到侧壁上的离子以一定角度从下往上注入到样品表面,这是由于碰撞效应造成的。从能量和剂量的角度,存在一个合适的脉冲宽度,过大的脉宽会引起剂量不均匀性增加,同时离子注入能量也会下降。

仰角可调摇臂式喷头水力性能试验

在不改变喷头原有结构的基础上,设计了一种由上支撑杆、下支撑杆、限位杆、柔性波纹管组件、内螺纹空心轴、定位螺钉、调节螺钉等组成的喷头仰角调节机构,实现喷头仰角在13°、18°、23°、30°4个角度的调节,并对安装了该机构的喷头进行了水力性能试验。结果表明,喷头仰角为23°时,不同工作压力下喷头的射程均最大;在23°与30°时组合均匀度系数相对较大,最利于组合喷灌。不同工作压力下,平均喷灌强度随着喷头仰角的减小而增大。喷头仰角由23°减小到13°时,喷头喷洒水滴的飘移损失减小,平均喷灌强度增加,因此喷头仰角减小可以增强其抗风、抗坡能力。仰角越小,喷头射程末端降水量变化越剧烈,导致喷头喷洒降水量分布不均,所以仰角调节不宜过小。安装了仰角调节机构的喷头在各象限的转动误差均小于±10%,其转动均匀性符合要求。

基于3D打印技术的复杂三维粗糙裂隙网络渗流特性试验及数值模拟研究

准确地评价岩体裂隙网络渗流特性是地下工程建设与环境安全的重要基础。构建了模拟真实岩体裂隙网络结构的三维数字模型,利用3D打印技术制作了三维粗糙裂隙网络模型试样,进行了不同边界条件下的渗流试验,并采用数值模拟方法进一步研究了裂隙表面粗糙性对渗流特性的影响。研究结果表明:随着注入水流流速的增加,模型中因惯性效应引起的水头损失逐渐增大,试样进出口之间水压差与流量的关系由线性向非线性转变,转折点对应的临界水力梯度范围为0.015~0.195。三维裂隙网络非线性流动特性可以采用Forchheimer方程表征,其中由惯性力引起的压降与总压降的比值随着水力梯度的增加而增大,但增幅逐渐降低,当水力梯度接近1.0时,惯性力引起的压降占总压降的比例高达68.5%。裂隙网络的空间分布特征决定了模型的整体连通性,而裂隙开度的非均匀性进一步使得流体在连通裂隙中将选择渗透性较大、阻力较小的通道优先流动,导致裂隙网络中主要流动区域面积与裂隙总面积比小于41%。裂隙表面粗糙性会降低三维裂隙网络模型的渗透性,且随着表面粗糙度增加,渗透性降低幅度越大,但裂隙开度的增加会削弱裂隙表面粗糙性对其渗透性的影响。提出的研究方法为定量化表征岩体复杂三维裂隙网络渗流特性提供了可靠途径。

Effect of melt superheat on structural uniformity of lotus-type porous metals prepared by unidirectional solidification

Structural uniformity is an important parameter influencing physical and mechanical properties of lotus-type porous metals prepared by directional solidification of metal-gas eutectic (Gasar). The effect of superheat on structural uniformity as well as average porosity, pore morphology of porous metals was studied. The experimental results show that, when the superheat is higher than a critical value (ΔTc), the bubbling or boiling phenomenon will occur and the gas bubbles will form in the melt and float out of the melt. As a result, the final porosity will decrease. In addition, a higher superheat will simultaneously cause a non-uniform porous structure due to the pores coalescence and bubbling phenomenon. Finally, a theoretical model was developed to predict the critical superheat for the hydrogen to escape from the melt and the corresponding escapement ratio of hydrogen content. Considering the escapement of hydrogen, the predicted porosities are in good agreement with the experimental results.

Study on Various Rectifiers for Fan-Filter Units

The face velocities of the high efficiency particulate air filters and the ultra low penetration airfilters in fan filter units (FFUs) have large relative standard deviation and turbulivity. It seriously affects the unidirectivity of the flow in the unidirectional flow clean zone and cleanroom. The cross contamination in this kind of unidirectional flow area is hardly controlled. It is significant to find optional method for keeping the face velocity uniformity of FFU and reducing the face velocity turbulivity of FFU, furthermore, to keep the cleanliness level under FFUs. The normal and easy method is to add flow rectifiers under filters. FFUs with various flow rectifiers have been tested. The uniformity and turbulivity of facevelocity under the FFU are presented in this paper. The influence of the facevelocity uniformity and turbulivity on the contamination boundary of the unidirectional flow is studiedas well.

Characterizing heterogeneity in vehicular traffic speed using two-step cluster analysis

In order to analyze the heterogeneity in vehicular traffic speed, a new method that integrates cluster analysis and probability distribution function fitting is presented. First, for identifying the optimal number of clusters, the two-step cluster method is applied to analyze actual speed data, which suggests that dividing speed data into two clusters can best reflect the intrinsic patterns of traffic flows. Such information is then taken as guidance in probability distribution function fitting. The normal, skew-normal and skew-t distribution functions are used to fit the probability distribution of each cluster respectively, which suggests that the skew-t distribution has the highest fitting accuracy; the second is skew-normal distribution; the worst is normal distribution. Model analysis results demonstrate that the proposed mixture model has a better fitting and generalization capability than the conventional single model. In addition, the new method is more flexible in terms of data fitting and can provide a more accurate model of speed distribution.

A BEEM Study on Effects of Annealing Temperature on Barrier Height Inhomogeneity of CoSi_2/Si Contact Formed in Co-Ti-Si Systems

Ultra thin epitaxial CoSi 2 films are fabricated by solid state reaction of a deposited bilayer of Co(3nm)/Ti (1nm) on n Si(100) substrates at different temperatures.The local barrier heights of the CoSi 2/Si contacts are determined by using the ballistic electron emission microscopy (BEEM) and its spectroscopy (BEES) at low temperature.For CoSi 2/Si contact annealed at 800℃,the spatial distribution of barrier heights,which have mean barrier height of 599meV and a standard deviation of 21meV,obeys the Gaussian Function.However,for a sample that is annealed at 700℃,the barrier heights of it are more inhomogenous.Its local barrier heights range from 152meV to 870meV,which implies the large inhomogeneity of the CoSi 2 film.

二水平因子设计的均匀性模式及其相关的准则

从几何的角度研究二水平因子设计的投影性质.基于一种类似于字长型的均匀性模式,提出了用于比较二水平因子设计的均匀性分辨度和最小低阶投影均匀性两个准则,并建立了最小低阶投影均匀性与最小低阶混杂、广义最小低阶混杂、正交性等准则之间的密切联系.这些联系进一步揭示了均匀设计和因子设计之间的内在关系,对最小低阶混杂、广义最小低阶混杂、正交性等准则提供了合理的几何解释.

Time-temperature-property curves for quench sensitivity of 6063 aluminum alloy

The quench sensitivity of 6063 alloy was investigated via constructing time-temperature-property（TTP） curves by interrupted quenching technique and transmission electron microscopy（TEM） analysis.The results show that the quench sensitivity of 6063 alloy is lower than that of 6061 or 6082 alloy,and the critical temperature ranges from 300 to 410℃ with the nose temperature of about 360℃.From TEM analysis,heterogeneous precipitate β-Mg2Si is prior to nucleate on the（AlxFeySiz） dispersoids in the critical temperature range,and grows up most rapidly at the nose temperature of 360℃.The heterogeneous precipitation leads to a low concentration of solute,which consequently reduces the amount of the strengthening phase β＇＇ after aging.In the large-scale industrial production of 6063 alloy,the cooling rate during quenching should be enhanced as high as possible in the quenching sensitive temperature range（410-300℃） to suppress the heterogeneous precipitation to get optimal mechanical properties,and it should be slowed down properly from the solution temperature to 410℃ and below 300℃ to reduce the residual stress.

航空橡胶密封材料试验用金属浴试验箱的研制

本文设计了一种金属浴试验箱,该试验箱主要用于测试胶/漆材料在设定温度环境下的耐油试验。采用加热棒进行加热,可实现装置在50-220℃的自动控温。设计了四个尺寸为Φ80×260 mm的测试腔,温度波动度不超过0.2℃·min^-1,温度均匀性不超过2℃。该金属浴试验箱波动度小,加热均匀,非常适用于橡胶密封材料的高温耐油试验。

Significant improvements in mechanical properties of AA5083 aluminum alloy using dual equal channel lateral extrusion

Dual equal channel lateral extrusion (DECLE), as a severe plastic deformation (SPD) process, was employed forimproving the mechanical properties of AA5083 aluminum alloy. Several experiments were conducted to study the influences of theroute type, namely A and B, and pass number on mechanical properties of the material. The process was conducted up to 6 passeswith decreasing process temperature, specifically from 573 to 473 K. Supplementary experiments involving metallography, hardnessand tensile tests were carried out in order to evaluate the effects of the process variables. The hardness measurements exhibitedreasonably uniform distributions within the product with a maximum increase of 64% via a 6-pass operation. The yield and ultimatestrengths also amended 107% and 46%, respectively. These significant improvements were attributed to the severe shear deformationof grains and decreasing pass temperature, which intensified the grain refinement. TEM images showed an average grain sizereduction from 100 μm for the annealed billet to 200 nm after 6 passes of DECLE. Finally, the experimental findings for routes A andB were compared and discussed and some important conclusions were drawn.

Relationships between microhardness, microstructure, and grain orientation in laser-welded joints with different welding speeds for Ti6Al4V titanium alloy

The microhardness curve trend and its relationships with microstructure and misorientation were analyzed to enhance the comprehension of the microstructure and mechanical property of micro-areas in Ti6 Al4 V laser-welded joints with different welding speeds. The microhardness measured on the fusion line(H_m) is the highest from the weld center to the base metal. H_m increases with increasing weld width in a welded joint and increasing degree of the non-uniformity in all studied welded joints. The microhardness decreases from the weld metal to the base metal with decreasing amount of martensite α’ and increasing amount of original α phase. When the microstructure is mainly composed of martensite α’, the microhardness changes with the cooling rate, grain size of the martensite, and peak values of the fraction of misorientation angle of the martensite in a wide weld metal zone or weld center at different welding speeds, whereas the difference is small in a narrow weld metal zone.

3D FEM simulations and experimental validation of plastic deformation of pure aluminum deformed by ECAP and combination of ECAP and direct extrusion

Rigid-viscoplastic3D finite element simulations(3D FEM)of the equal channel angular pressing(ECAP),thecombination of ECAP+extrusion with different extrusion ratios,and direct extrusion of pure aluminum were performed andanalyzed.The3D FEM simulations were carried out to investigate the load-displacement behavior,the plastic deformationcharacteristics and the effective plastic strain homogeneity of Al-1080deformed by different forming processes.The simulationresults were validated by microstructure observations,microhardness distribution maps and the correlation between the effectiveplastic strain and the microhardness values.The3D FEM simulations were performed successfully with a good agreement with theexperimental results.The load-displacement curves and the peak load values of the3D FEM simulations and the experimentalresults were close from each other.The microhardness distribution maps were in a good conformity with the effective plastic straincontours and verifying the3D FEM simulations results.The ECAP workpiece has a higher degree of deformation homogeneity thanthe other deformation processes.The microhardness values were calculated based on the average effective plastic strain.Thepredicted microhardness values fitted the experimental results well.The microstructure observations in the longitudinal andtransverse directions support the3D FEM effective plastic strain and microhardness distributions result in different formingprocesses.