Complicated motion of particles on vibration screen surface

The particles’ motion on screen surface was studied by the way of nonlinear dynamics. It was found that the particles’ motion may be changed from one form to another with its vibration strength. When the vibration strength K is bigger than 1 and smaller than 1. 33, the particles’ motion is the bifurcating type;when K is bigger than 1. 33 and smaller than 1. 67, its motion becomes the double bifurcation type; when K is bigger than 1. 67, its motion changes into chaos motion type. On basis of studying all effects of large vibration strength on particles penetrating, it was pointed out that a larger vibration strength K of screen surface will increase the strength of particles’ motion, and then increase their probability of penetrating screen surface. A primary theory of particles’ motion under large vibration strength for moisture fine coal was established.

A strategy of screening and binding analysis of bioactive components from traditional Chinese medicine based on surface plasmon resonance biosensor

Elucidating the active components of traditional Chinese medicine(TCM)is essential for understanding the mechanisms of TCM and promote its rational use as well as TCM-derived drug development.Recent studies have shown that surface plasmon resonance(SPR)technology is promising in this field.In the present study,we propose an SPR-based integrated strategy to screen and analyze the major active components of TCM.We used Radix Paeoniae Alba(RPA)as an example to identify the compounds that can account for its anti-inflammatory mechanism via tumor necrosis factor receptor type 1(TNF-R1).First,RPA extraction was analyzed using an SPR-based screening system,and the potential active ingredients were collected,enriched,and identified as paeoniflorin and paeonol.Next,the affinity constants of paeoniflorin and paeonol were determined as 4.9 and 11.8 mM,respectively.Then,SPR-based competition assays and molecular docking were performed to show that the two compounds could compete with tumor necrosis factor-a(TNF-a)while binding to the subdomain 1 site of TNF-R1.Finally,in biological assays,the two compounds suppressed cytotoxicity and apoptosis induced by TNF-a in the L929 cell line.These findings prove that SPR technology is a useful tool for determining the active ingredients of TCM at the molecular level and can be used in various aspects of drug development.The SPR-based integrated strategy is reliable and feasible in TCM studies and will shed light on the elucidation of the pharmacological mechanism of TCM and facilitate its modernization.

Dynamic analysis of elastic screen surface with multiple attached substructures and experimental validation

A feasible method to improve the reliability and processing efficiency of large vibrating screen via the application of an elastic screen surface with multiple attached substructures （ESSMAS） was proposed. In the ESSMAS, every screen rod, with ends embedded into elastomer, is coupled to the main screen structure in a relatively flexible manner. The theoretical analysis was conducted, which consists of establishing dynamic model promoted from the fuzzy structure theory as well as calculating for the equivalent stiffness of each attached structure. According to the numerical simulation using the NEWMARK-fl integration method, this assembling pattern significantly leads to the screen surface/rod having larger vibration intensity than that of the corresponding position on screen structure, which specifically, with an averaged acceleration amplitude increasing ratio of 11.37% in theoretical analysis and 20.27% in experimental test. The experimental results, within a tolerant error, also confirm the established model and demonstrate the feasibility of ESSMAS.

Dynamic analysis of new type elastic screen surface with multi degree of freedom and experimental validation

A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were coupled to the main screen structure with ends embedded into the elastomers, and the secondary robs were attached to adjacent two primary robs with elastic bands. The dynamic model of vibrating screen with NTESSMDF was established based on Lagrange's equation and the equivalent stiffnesses of the elastomer and elastic band were calculated. According to numerical simulation using the 4th order Runge-Kutta method, the vibration intensity of screen surface can be enhanced substantially with an averaged acceleration amplitude increasing ratio of 72.36%. The primary robs and secondary robs vibrate inversely in steady state, which would result in the friability of materials and avoid stoppage. The experimental results validate the dynamic characteristics with acceleration amplitude rising by62.93% on average, which demonstrates the feasibility of NTESSMDF.

A novel four-legged loaded element thick-screen frequency selective surface with a stable performance

A thick-screen frequency selective surface （FSS） has not only a broad bandwidth but also the advantages of overcoming the multilayer FSS shortcoming of complex structure and low transmittance of centre frequency due to the cascade of FSSs, and this means it could potentially be applied in a stealth curved streamlined radome. However, there is an unsteadiness of centre frequency in a wide range of incident angles and another unsteadiness of polarization in a big incident angle. In order to solve these problems, in this paper we provide a novel four-legged loaded element thick-screen FSS. The structure is analysed and simulated using the mode matching method and moment method. The centre frequency, the transmittance of centre frequency, and bandwidth of the structure are investigated when some parameters including the polarization at a big incident angle and the incident angles of TE ＆： TM waves are changed. The novel four-legged loaded element thick-screen FSS has better transmission properties with a better steadiness of polarization and incident angle independence. The novel structure of the four-legged loaded element thick-screen FSS provides a valuable reference for their application in a stealth curved streamlined radome.

Force measurement between mica surfaces in electrolyte solutions

The forces between two molecularly smooth mica surfaces are measured in monovalent and divalent cations electrolyte solutions by a surface force apparatus （SFA）. The properties of K＋, Na＋, and Mg2＋ between molecularly smooth mica surfaces are investigated. The Derjagui-Landau- Verwey-Overbeek （DLVO） force and the hydration force are detected in the experiment. The results show that in lower concentrations of a monovalent electrolyte solution （about 10-4 mol/L）, the force curves are completely in good agreement with those computed by the DLVO theory. However, additional short-range repulsive forces which deviate from the DLVO theory are observed when the concentrations of cations are above the critical bulk concentration, which is different for each electrolyte. The results show the properties of these cations on both the screening effect adsorbed on the mica surface and the hydration in solution. From the results, the interaction energy between two hydrated ions of potassium or sodium can also be estimated.

Design and Measurement of Microwave Absorbers Comprising Resistive Frequency Selective Surfaces

Frequency selective surfaces (FSSs) have been successfully used in constructing microwave absorbers which demonstrate the ability of modifying and improving its absorbing performances. In this paper, microwave absorber based on ferromagnetic nano-films has been proposed and investigated with a structure similar to that of the Salisbury screen except that the resistive sheet is replaced by FSS of square patch array of the nano-film. We have explored the FSS absorber from three aspects: equivalent circuit model, electromagnetic full-wave simulation and the actual sample measurement. By carefully tuning the patch size, the thickness of the dielectric spacer and the specification of the ferromagnetic nano-film, we obtain the optimized performance of broadband microwave absorbing. Due to the light weight of the nano-films, the proposed absorbers can achieve an ultra-low surface density less than 0.25 kg/m2.

Nonlinear magneto-mechanical-thermo coupling characteristic analysis for transport behaviors of carriers in composite multiferroic piezoelectric semiconductor nanoplates with surface effect

In this paper,to better reveal the surface effect and the screening effect as well as the nonlinear multi-field coupling characteristic of the multifunctional piezoelectric semiconductor(PS)nanodevice,and to further improve its working performance,a magneto-mechanical-thermo coupling theoretical model is theoretically established for the extensional analysis of a three-layered magneto-electro-semiconductor coupling laminated nanoplate with the surface effect.Next,by using the current theoretical model,some numerical analyses and discussion about the surface effect,the corresponding critical thickness of the nanoplate,and the distributions of the physical fields(including the electron concentration perturbation,the electric potential,the electric field,the average electric displacement,the effective polarization charge density,and the total charge density)under different initial state electron concentrations,as well as their active manipulation via some external magnetic field,pre-stress,and temperature stimuli,are performed.Utilizing the nonlinear multi-field coupling effect induced by inevitable external stimuli in the device operating environment,this paper not only provides theoretical support for understanding the size-dependent tuning/controlling of carrier transport as well as its screening effect,but also assists the design of a series of multiferroic PS nanodevices.

Instantly Investigating the Adsorption of Polymeric Corrosion Inhibitors on Magnesium Alloys by Surface Analysis under Ambient Conditions

Surface engineering of magnesium alloys requires adequate strategies, processes and materials permitting corrosion protection. Liquid formulations containing corrosion inhibitors often are to be optimized according to the demands of the respective substrate and following the service conditions during its application. As an interdisciplinary approach, a combination of several techniques for instantly monitoring or elaborately analyzing the surface state of magnesium was accomplished in order to characterize the performance of new adsorbing sustainable amphiphilic polymers which recently were developed to facilitate a multi-metal corrosion protection approach. The application of established techniques like Contact Angle measurements and X-ray Photoelectron Spectroscopy investigations was supplemented by introducing related and yet faster online-capable and larger-scale techniques like Aerosol Wetting Test and Optically Stimulated Electron Emission. Moreover, an inexpensive setup was configured for scaling the inset and the extent of degradation processes which occur at local electrochemical circuits and lead to hydrogen bubble formation. Using these analytical tools, changes of the surface state of emeried AM50 samples were investigated. Even in contact with water, being a moderate corrosive medium, the online techniques facilitated detecting surface degradation of the unprotected magnesium alloy within some seconds. In contrast, following contact with a 1 weight% formulation of a polymeric corrosion inhibitor, surface monitoring indicated a delay of the onset of degradation processes by approximately two orders of magnitude in time. Mainly based on the spectroscopic investigations, the corrosion inhibiting effects of the investigated polymer are attributed to the adsorption of a primary polymer layer with a thickness of a few nanometers which occurs within some seconds. Immersion of magnesium for several hours brings up a protective film with around ten nanometers thickness.

基于TOF相机的振动筛上物料状态动态监测方法

振动筛筛上物料载荷异常不仅影响生产效率还可能导致安全隐患,实时准确地监测筛上物料状态具有重要意义。针对传统人工监测方法劳动强度大、速度慢、有极高安全隐患并且不容易发现设备微小故障等问题。基于TOF相机物料动态监测技术,提出了一种联合KD树与帧差法的点云数据补全方法和基于曲面重构的筛上物料动态监测方法。该点云数据补全方法有效修补了因筛上物料表面水分和物料缝隙导致的TOF相机拍摄过程中的点云数据缺失问题,通过对补全后的筛上物料进行点云曲面重构分析,判断欠载、过载、左偏载和右偏载四种筛上物料状态,实时监测筛上物料状态。研究通过TOF相机直接获取筛上物料状态信息,对筛上物料实时检测,减少了人工干预的需求且具备实时性。为筛上物料状态实时监测问题提供了一个可靠的解决方案。

基于活性炭颗粒的圆振动筛主要技术参数优化分析

为验证圆运动振动筛在对活性炭颗粒筛分时,振动筛各运动参数对筛分效率的影响,采用平均筛分效率来代表活性炭筛分效果。采用Box-Behnken响应面分析来研究圆运动振动筛的振动幅度、运动倾角以及振动频率对筛分效果的影响并进行仿真模拟,探讨3个因素之间对活性炭筛分的影响作用。验证结果表明:对筛分效果影响最大的是振动频率,影响最弱的是运动倾角,振动幅度和运动倾角之间具有显著影响作用,在振动幅度为4.21 mm、运动倾角16.07°以及振动频率13.83 Hz时筛分效果达到最大值40.86%。通过该方法优化的圆振动筛,可提高活性炭的筛分效率。

新型螺旋筛面旋振筛的参数优化

为研究螺旋筛面旋振筛的筛分效率与筛分参数之间的非线性关系,文章使用神经网络对其筛分参数综合寻优,得到最佳筛分参数及筛分效率。首先,建立不同结构参数的螺旋筛面旋振筛三维模型,利用离散单元法对其仿真模拟,获取不同参数下的筛分效率数据。然后,利用神经网络对样本数据进行训练、验证及得到预测数据。研究结果表明:通过神经网络的训练和测试,证明神经网络可以用于螺旋筛面旋振筛的参数优化;在螺旋升角为11.613°、振动频率为15.720 Hz、振动幅度为1.481 mm、螺旋圈数为1.468圈、内外径比值为0.256时,螺旋筛面旋振筛获得最佳筛分效率,并且优化了螺旋圈数,缩短了筛长。

芝麻籽粒植酸含量高通量检测方法的建立与低植酸种质的筛选

【目的】植酸是芝麻中主要的抗营养成分之一。探究芝麻籽粒植酸高效提取最优条件,建立植酸含量高通量检测方法,并应用于芝麻群体材料植酸含量变异检测和低植酸种质资源筛选,推动芝麻植酸基础研究和低植酸品种选育。【方法】以0.4 mol·L-1 HCl为提取溶剂,进行种子量、捣碎时间、捣碎频率、提取液体积等单因素试验,对芝麻籽粒植酸进行提取,结合微量化铁沉淀法高通量测定植酸含量。在单因素试验的基础上,进行Box-Behnken四因素三水平的响应面试验,建立植酸得率为响应值的二次多项式回归方程模型,并绘制响应曲面图和等高线图,分析影响植酸得率的主要因素及各因素间的交互作用,确定植酸含量检测的最优提取条件。利用该参数条件对2个环境下种植的200份芝麻种质资源进行植酸含量测定,筛选低植酸种质。【结果】方差分析显示,建立的回归模型具有高度显著性(P<0.0001),失拟项不显著(P>0.05),方程对试验拟合较好,可用此回归方程对芝麻籽粒植酸提取试验进行优化。4个因素的一次项对植酸得率的影响均达到极显著水平,对植酸得率的影响大小依次为种子量>捣碎时间>捣碎频率>提取液体积。响应面分析图表明,种子量和捣碎时间、种子量和捣碎频率、捣碎时间和捣碎频率、捣碎时间和提取液体积、捣碎频率和提取液体积之间具有一定的交互作用。经过单因素条件及响应面设计优化的植酸最佳提取条件参数为种子量30 mg、捣碎时间6.5 min、捣碎频率50 Hz、提取液体积435μL,在此条件下的植酸得率预测值为14.03 mg·g^(-1),实际植酸平均得率为14.14 mg·g^(-1),模型预测值与试验实际值十分接近。从200份种质资源中筛选出3份稳定的低植酸芝麻种质,平均含量为11.63 mg·g^(-1)。【结论】建立了芝麻植酸高效提取检测技术,可以显著减少试验时长,减少样品使用量,检测结果重复性好,准确性高。

表面织构-活性屏离子氮化复合处理对38CrMoAl钢摩擦学行为的影响

【目的】38CrMoAl钢是液压泵柱塞常用材质之一,其表面性能对液压泵长寿命安全服役尤为重要。磨损是液压泵柱塞的主要失效方式,采用表面强化处理能够突破其性能极限,是实现液压泵高性能、高可靠运行的有效途径。【方法】采用表面织构化和活性屏离子氮化的复合处理工艺对38CrMoAl钢进行表面形性调控,以期实现其表面强化方法。先利用激光加工技术在38CrMoAl钢表面制备凹坑织构,再对38CrMoAl钢和表面织构化38CrMoAl钢进行活性屏离子氮化处理。借助球-盘式摩擦磨损试验机研究表面织构-活性屏离子氮化复合处理对38CrMoAl钢摩擦学行为的影响。【结果】结果表明,38CrMoAl钢表面生成了ε-Fe2-3N、γ'-Fe4N和CrN;氮化层表面致密且无明显裂纹和孔洞;氮化层均匀、连续,由白亮层和扩散层组成。氮化层的截面硬度呈梯度分布,试样表面硬度最高,随着距表面距离的增大,硬度逐渐降低。38CrMoAl钢相关试样与Al_(2)O_(3)球的干滑动摩擦结果可知,38CrMoAl钢的摩擦系数为0.40,而表面织构-活性屏离子氮化38CrMoAl钢的摩擦系数为0.36;经复合处理后,38CrMoAl钢的磨损失重降低了92.5%.复合处理显著提高了38CrMoAl钢的摩擦学性能。

基于曲面拟合的光学偏折系统显示屏标定方法

针对透射式光学偏折系统中最关键的标定环节,提出使用曲面拟合方式拟合显示屏幕面形分布。建立基于透射式光学偏折术的波前检测仿真模型,分析两种不同的显示屏面形拟合方法对波前测量的影响。仿真结果显示:平面屏幕模型波前像差均方根误差(RMS)值为0.8375μm,而曲面屏幕模型仿真波前像差RMS值仅为0.0596μm。采用透射式光学偏折系统对球面透镜进行波前测量,曲面屏幕模型中波前像差RMS值为0.1371μm,平面屏幕模型中波前像差RMS值为1.4326μm。实验结果表明:使用曲面拟合效果明显优于平面拟合效果,证明了曲面拟合屏幕模型的可行性。

复合菌群构建及其石油烃降解特性

为获得高效降解石油烃复合菌群,对实验室保存的菌株进行石油烃降解效果及原油4组分降解能力分析研究,筛选出了4株菌(A1、A3、Y3、Y4),对其进行ITS和16S rRNA分子鉴定,确认4株菌的分类信息,并优化高效降解菌株的复配方式。结果显示:A1属于不动杆菌属(Acinetobacter)、A3属于芽胞杆菌属(Bacillus)、Y3和Y4均为假丝酵母菌属(Candida);A1、A3、Y3、Y4对石油烃的降解率分别为42.27%、40.95%、62.02%、69.84%;其中Y4对烷烃和芳烃降解效果最佳,降解率分别为65.71%和23.69%,沥青质降解效果最好的是A1,胶质降解效果最好的是Y3,降解率分别为22.74%和21.22%,A3对各组分降解能力均衡;A1、A3、Y4复合的菌群降解效果最佳,其降解率高达83.11%,相较于单一菌株提高了1.19—2.03倍;A1、A3、Y4的最佳接种量比例为0.9∶0.9∶1.5,其降解率可达88.34%。该研究成功筛选出一种新的高效降解石油烃的菌群,对进一步研究和应用于石油污染治理具有重要指导意义。

高产乙酸乙酯酵母的筛选鉴定及发酵条件优化

该研究通过传统培养分离方法及测定乙酸乙酯产量从清香型白酒大曲中分离筛选高产乙酸乙酯的酵母菌株,通过形态观察及分子生物学技术对其进行菌种鉴定,并对其耐受性进行分析。以乙酸乙酯产量为响应值,采用单因素试验及响应面试验对筛选菌株的发酵条件进行优化。结果表明,分离筛选得到1株高产乙酸乙酯的酵母菌株,编号为YM001,经鉴定,其为异常威克汉姆酵母(Wickerhamomyces anomalus)。该菌株具有较强的耐受性,在乙醇体积分数10%,乙酸含量0.08%、温度50℃、pH 2、乙酸乙酯含量30 g/L、NaCl含量150 g/L、葡萄糖含量50 g/L的条件下仍能生长,能够较好地适应白酒酿造环境。异常威克汉姆酵母YM001产乙酸乙酯的最优发酵条件为:接种量4%、乙醇体积分数4%、乙酸添加量0.02%、初始糖度9°Bx、初始pH值6、转速210 r/min、发酵温度22℃、第2阶段发酵时间36 h。在此发酵条件下,异常威克汉姆酵母YM001的乙酸乙酯产量最高,达(17.39±0.362)g/L。

伊力特浓香型大曲中优良霉菌的筛选鉴定及其麸曲制曲工艺研究

该研究采用传统培养分离法从伊力特浓香型大曲中分离筛选高产糖化酶和液化酶活力的霉菌,并通过形态学观察及分子生物学技术对其进行菌种鉴定。利用筛选菌株制作麸曲,并以糖化酶及液化酶活力为评价指标,采用单因素试验及响应面试验对其制曲条件进行优化。结果表明,筛选得到一株产糖化酶、液化酶性能优良的霉菌,编号为JW-3,经鉴定其为伞枝横梗霉(Lichtheimia corymbifera)。使用伞枝横梗霉JW-3制作纯菌种麸曲的最佳制曲条件为接种量10%,培养温度30℃,培养时间91 h,水分含量55%。在此优化条件下,霉菌纯菌种麸曲的糖化酶活力为409.67 U/g,液化酶活力为1597.00 U/g,在白酒酿造过程中具有一定的应用潜力。

探测距离对光幕系统探测灵敏度影响研究

针对探测距离会对光幕系统探测灵敏度产生影响,分别建立弹丸进入系统时遮挡激光产生的光通量变化与系统接收弹丸反射激光功率的数学模型,得到最终弹丸过靶产生的光功率变化的数学模型,根据能够引起系统响应的最小光功率,得出了弹丸处于不同探测距离条件下光幕系统能够探测最小弹丸的尺寸,最后通过实验对数学模型结果进行验证。该研究对于根据所需探测灵敏度设计合理探测靶面,具有重要意义。

高产乙酸乙酯酵母菌的筛选鉴定及发酵条件优化

该研究采用传统培养分离法及乙酸乙酯产量测定从浓香型白酒酒醅中分离筛选高产乙酸乙酯的酵母菌,通过形态学观察、生理生化试验和ITS序列分析对其进行菌种鉴定,并以乙酸乙酯产量为响应值,通过单因素试验、Plackett-Burman试验和响应面试验对其发酵工艺进行优化。结果表明,分离筛选得到一株高产乙酸乙酯的酵母菌株,编号为Q5-1,经鉴定,其为异常威克汉姆酵母(Wickerhamomyces anomalus)。异常威克汉姆酵母Q5-1发酵产乙酸乙酯的最佳发酵条件为葡萄糖98 g/L、酵母粉19 g/L、初始pH为6.8、接种量6%、发酵时间48 h。在此条件下,乙酸乙酯产量达到4.89 g/L,是优化前的2.49倍,该结果对发酵食品中产香(乙酸乙酯)酵母功能菌的开发利用,以及乙酸乙酯的生物合成与工业化生产具有重要的参考价值。