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1.
Spot welding was widely applied inindustries such asaviation, automobile , and other production departments .Aluminumstructures gradually take a prominent positionowingto lightweight and high intensity. But in quality in-spectionof aluminumalloys ,a single electrical parameter orthermal parameters[1]cannot effectivelyforecast the diame-ter of the weld nugget ,the intensity of spot weld, andsplashing duetotheinstabilityof weldzone caused byalloycompositions and fragile surface oxidation. Theref… 相似文献
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ZnS∶Cu纳米微粒的制备及其光学性能 总被引：1，自引：0，他引：1
利用微乳液法制备出ZnS∶Cu纳米微粒 .透射电子显微镜 (TEM )和动态光散射 (DLS)测试结果表明 ,所得微粒粒径为 2～ 8nm .XRD结果表明 ,ZnS∶Cu纳米微粒为立方晶型结构 ,与体材料ZnS的晶型结构一致 ;在紫外吸收光谱中 ,ZnS∶Cu纳米微粒吸收峰蓝移 .发射光谱表明ZnS∶Cu纳米微粒产生一个位于 482nm的绿色发射带 相似文献
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This paper presents a novel method of identifying coal type based on mechanistic methods. The ratio of the resonance line spectrum of a luminous flame and the continuous spectrum at the same wavelength eliminates the influence of temperature on spectral intensity. The atomic line spectra of Na and K are typical and significant over continuous flame spectra. The concentrations of elemental Na and K in the flame are exclusively relative to coal type and composition. Using an experimental furnace and charge-coupled device (CCD) optical spectrometer apparatus, the continuous spectra and atomic line spectra of Na and K elements were sampled from coal flames in real time. An empirical fitting method was used to simplify the formulas of absorption strength and flame temperature calculation, and rational solutions were obtained by using an iterative algorithm. Due to the change in reaction rate and absorption by soot particles, the relative contents of Na and K in a flame vary with the temperature and absorption strength. Arrhenius’s equation for temperature compensation was adopted. Compensation for soot density in the furnace was also satisfied by an exponential expression. At any one sampling position, the compensation parameters were identical for all coal types. After compensation for temperature and density of soot particles, the relative strength of the Na and K signals and the ratio between them uniquely matched the coal type burnt in various conditions. The results were replicated and verified in various conditions, and the response time of the system was of the order of seconds. 相似文献
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研究了变速齿轮箱CAD系统的总体设计框架,对变速箱中的齿轮啮合模型进行分析,并结合变速箱中齿轮受力与力矩的不同模型,给出了内部啮合齿轮参数化设计流程。设计了CAD系统的参数化绘图模块,给出了在AutoCAD的基础上进行二次开发的方法和过程。最后对变速齿轮箱CAD系统中的虚拟装配技术进行了研究和实现。 相似文献
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高分辨率单色仪和高灵敏度光电检测系统的广泛应用，使得拉曼光谱学迅速发展。利用各种类型的材料作为散射物质，都有可能得到相应的拉曼谱。该文通过样品实验，用拉曼散射测定分子的振动频率，进而分析出物质的分子结构。 相似文献
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采用高温固相法制备了CaBa2(BO3)2∶Eu2+绿色荧光粉,并对其发光性质进行了研究。该荧光粉在近紫外线激发下的发射光谱为峰值位于537 nm的带状谱,对应了Eu2+的4f65d1→4f7的特征跃迁发射;监测537 nm的发射峰,得到CaBa2(BO3)2∶Eu2+激发光谱为250~500 nm的宽带谱,能与产生350~410 nm辐射的UVLED管芯很好地匹配。Eu2+掺入量和H3BO3的用量对样品发光强度都有影响,当Eu2+的掺入量达到2%,H3BO3用量为理论用量的1.03倍时,样品可达到最佳发光亮度。 相似文献
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研究一种基于STC12C5A60S2增强型单片机作为主控芯片的光立方音频谱显示方案。以STC单片机为核心,以74HC573为锁存器,采用与点阵相同的动态扫描驱动显示原理,实现LED的光立方显示。同时利用音频输入,结合FFT算法,实现音频谱的光立方显示,给人以良好的视觉和听觉感受。 相似文献
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A new blue electroluminescent material,distyrylarylene(DSA)derivative,4,4‘-bis[2,2-(1-naphthyl,phenyl)vinyl]-1,1-biphenyl(NPVBi)is designed and synthesized.The DSA derivative shows better thermal stability because of its high glass transition temperature.A blue organic light emitting diode(OLED0with the structure ITO/TPD/NPVBi/Alq/LiF/Al is studied.The electroluminescent(EL0spectrum of the OLED exhibits that light emission originates from NPVBi with a peak at 460nm,its Commission Internationale de l‘Eclairage(CIE)color coordinates are x=0.16,y=0.15,and showing independence of CIE color coordinates on current density.The new DSA derivative is expectable as a new candidate for blue light emitter in OLEDs. 相似文献
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相较于传统单点传感器检测火灾的方法,采用视频检测火灾更快、更可靠,而且可以提供火灾大小、增速等直观的图像信息。结合图像处理技术,设计一种可以同时检测火焰和烟雾的视频火灾检测方法。首先,通过提取移动区域的方式,并利用改进的火灾颜色模型提取出疑似火灾区域;然后,选出抗干扰能力强的火灾特征并对提取各特征的方法进行设计;最后,将火焰特征输入支持向量机进行火焰判别,将烟雾各特征与阈值比较后的结果输入可调节检测灵敏度的逻辑运算器进行烟雾判别,结合火焰与烟雾判别结果决定是否进行火灾预警。大量实验结果表明,该方法不仅可以检测明火,而且可以检测阴燃火,在检测准确率、误报率及反应时间上都有更好的表现。 相似文献
10.
一种新型的白光LED用红色荧光粉SrMoO4:Eu3+ 总被引：1，自引：0，他引：1
采用固相法合成了红色荧光粉SrMoO4:Eu3 并对它的发光性质进行了研究。它的激发谱为双峰结构,两主峰分别位于394nm的近紫外区和464nm的蓝色可见光区。发射谱为线谱,主峰峰值为624nm,这是能与紫外和蓝色芯片符合的很好的红光。所以它是一种很好的制备白光LED用的荧光粉材料。 相似文献
11.
This study investigates the effectiveness of a teaching conflict procedure whose purpose was the transformation of the representations
of 12–16-year-old pupils in Greece concerning light emission and shadow formation by extended light sources. The changes observed
during the children’s effort to destabilize and reorganise their representations towards a model that was compatible with
the respective scientific model were studied using three groups of pupils belonging to different age groups. The methodological
plan implemented was based on input from the History of Science, while the parameters of the geometrical optics model were
derived from Kepler’s relevant historic experiment. The effectiveness of the teaching procedure was evaluated 2 weeks after
the intervention. The results showed that the majority of the subjects accepted the model of geometrical optics, i.e. the
pupils were able to correctly predict and adequately justify the experimental results based on the principle of punctiform
light emission. Educational and research implications are discussed. 相似文献
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复杂网络理论可用于分析各领域的复杂系统。针对中国内地电影的复杂关系,设计网络建模算法,依据2017年票房榜排名前200的电影信息,以数据集中的实体为节点、实体之间的关系为边,构建复杂网络模型,基于该模型对2017年度中国内地电影复杂网络进行分析。结果表明,高产演员对票房无明显影响;介数中心性和特征向量中心性均小于特定值时,电影票房失败的概率较高;介数中心性和特征向量中心性分布在特定区域之内时,电影获得高票房的概率高达73%。建模实验与基于模型的分析证明了2017年中国内地电影复杂网络建模的有效性,揭示了电影票房和电影复杂网络中节点中心性之间的相关性。 相似文献
14.
采用聚氧化丙烯二醇（PPG）、异佛尔酮二异氰酸酯（IPDI）,甲苯二异氰酸酯（TDI）、二羟甲基丙酸（DMPA）等分别合成了IPDI型和TDI型水性聚氨酯（WPU）乳液,用共混的方法将阻燃剂FR-600引入到水性聚氨酯中,从而得到一系列阻燃水性聚氨酯。采用红外光谱对合成产物进行表征,并用氧指数仪、Zeta电位测试仪等对其性能进行研究。结果表明,阻燃剂FR-600能显著提高水性聚氨酯的阻燃性能,随着阻燃剂用量的增加,水性聚氨酯的极限氧指数不断增大,对于IPDI型水性聚氨酯,当阻燃剂FR-600的添加量为水性聚氨酯的8%时,其氧指数可达37%,使水性聚氨酯由可燃降低为不燃。对于TDI型水性聚氨酯,在阻燃剂添加量为10%时,其极限氧指数达到36%,达到了不燃级。粒径和Zeta电位测试表明,阻燃剂的加入对两种水性聚氨酯的粒径及稳定性影响不大。 相似文献
15.
文双春 《湖南城市学院学报》1998,(6)
根据经典辐射理论计算出了电子在线电流摇摆扬中运动产生的自发辐射强度分布;利用单粒子方法推导出了自发辐射与受激辐射的关系．结果表明：线电流摇摆场中自发辐射与受激辐射的关系与普通摆动器自由电子激光中的Ｍａｄｅｙ定理有非常相似的形式,但第二部分相差一个因子． 相似文献
16.
This research, carried out in Greece on pupils aged 12–16, focuses on the transformation of their representations concerning
light emission and image formation by extended light sources. The instructive process was carried out in two stages, each
one having a different, distinct target set. During the first stage, the appropriate conflict conditions were created by contrasting
the subjects’ predictions with the results of experimental situations inspired by the History of Science, with a view to destabilizing
the pupils’ alternative representations. During the second stage, the experimental teaching intervention was carried out;
it was based on the geometrical optics model and its parameters were derived from Kepler’s relevant historic experiment. For
the duration of this process and within the framework of didactical interactions, an effort was made to reorganize initial
limited representations and restructure them at the level of the accepted scientific model. The effectiveness of the intervention
was evaluated two weeks later, using experimental tasks which had the same cognitive yet different empirical content with
respect to the tasks conducted during the intervention. The results of the study showed that the majority of the subjects
accepted the model of geometrical optics, that is, the pupils were able to correctly predict and adequately justify the experimental
results based on the principle of punctiform light emission. Educational and research implications are discussed.
相似文献
| Christos DedesEmail: |
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以水杨醛为起始原料,在超声波辅助下,简便地合成了香豆素-3-羧酸（4）。利用紫外可见光光谱法和荧光光谱法研究了化合物（4）对一些有色金属离子的识别作用。结果表明,随着有色金属离子的加入,化合物（4）的紫外可见光光谱发生了红移和增色效应,荧光光谱发生猝灭现象;化合物（4）对Yb2＋的识别作用最优,络合常数为7.5×106M-1。 相似文献
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研究基于碳排放测算模型,从滁州农业生产中4个主要方面的碳源,测算了滁州2000-2009年农业碳排放量,并在此基础上进一步通过Kaya恒等式变形对滁州农业碳排放影响因素进行分解。研究结果表明：自2000年以来滁州农业碳排放总量和碳排放效率总体呈现上升态势,碳排放强度呈现缓慢下降趋势;生产模式因素、生产资料效率因素对碳排放量具有一定的抑制作用,但效果不够显著,分别累计实现15．66％、97．05％的碳减排;而经济规模因素、人口规模因素则对农业碳排放具有较强推动作用,分别累计产生195．86％、16．85％的碳增量。 相似文献
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马娅 《开封教育学院学报》2002,22(2):9-11
简·里斯 (Jean Rhys)的代表作《藻海无边》在诸多叙述方法中 ,象征性意象的设置是重要的手段之一。作品描绘了从飞蛾扑火到人扑火 ,从藻海无边到苦海无边 ,从丧失家园到丧失自我等象征性意象 ,使整个作品浸透着浓厚的幻灭感。这些意象在塑造典型和揭示主题方面都起到了画龙点睛的作用 相似文献