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Flow characterization and dilution effects of N2 and CO2 on premixed CH4/air flames in a swirl-stabilized combustor 下载免费PDF全文
Numerically-aided experimental studies are conducted on a swirl-stabilized combustor to investigate the dilution effects on flame stability, flame structure, and pollutant emissions of premixed CH4/air flames. Our goal is to provide a systematic assessment on combustion characteristics in diluted regimes for its application to environmentally-friendly approaches such as biogas combustion and exhanst-gas recirculation technology. Two main diluting species, N2 and CO2, are tested at various dilution rates. The results obtained by means of optical diagnostics show that five main flame regimes can be observed for Nz-diluted flames by changing excess air and dilution rate. CO2-diluted flames follow the same pattern evolution except that all the domains are shifted to lower excess air. Both N2 and CO2 dilution affect the lean blow- out (LBO) limits negatively. This behavior can be counter-balanced by reactant preheating which is able to broaden the flammability domain of the diluted flames. Flame reactivity is degraded by increasing dilution rate. Meanwhile, flames are thickened in the presence of both diluting species. NOx emissions are significantly reduced with dilution and proved to be relevant to flame stability diagrams: slight augmentation in NOx emission profiles is related to transitional flame states where instability occurs. Although dilution results in increase in CO emissions at certain levels, optimal dilution rates can still be proposed to achieve an ideal compromise. 相似文献
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To achieve a high-quality high-κ/Ge interfaces for high hole mobility Ge p-MOSFET applications,a simple chemical cleaning and surface passivation scheme is introduced,and Ge p-MOSFETs with effective channel hole mobility up to665 cm2/V·s are demonstrated on a Ge(111) substrate.Moreover,a physical model is proposed to explain the dipole layer formation at the metal–oxide–semiconductor(MOS) interface by analyzing the electrical characteristics of HCl- and(NH4)2S-passivated samples. 相似文献
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通过有效控制合成液配比,合成出了形貌规则、结晶度高且具有不同长径比的LTL型分子筛晶粒。采用"瓶中造船法",在不同长径比的LTL型分子筛晶粒孔道中组装稀土有机配合物,制得LTL分子筛/Eu-TTA主-客体荧光材料。荧光光谱表征结果表明,在激发波长为350 nm时,长径比为0.2的LTL分子筛/Eu-TTA晶粒在617 nm处的5D0→7F2发光强度最大,而长径比为3的晶粒发光强度最小。最后,将长径比为0.2的LTL分子筛/Eu-TTA晶粒在PEI修饰的玻璃表面快速擦涂10 s后,就制得厘米尺寸的一维取向LTL型分子筛荧光阵列。SEM表征结果证实,该分子筛荧光阵列中几乎所有的LTL分子筛晶粒都沿着与底基表面垂直的c轴方向一维高密度、单层有序排列。在激发波长为365 nm时,该一维取向LTL分子筛荧光阵列发出鲜艳的红色荧光。 相似文献
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为了能够更加直接地比较EAST 中第一壁水冷结构的传热能力,给出在未来设计中的选型参考,利用模拟分析的手段对现有的以及正在研制的水冷结构进行了在相同的工况下传热能力的对比分析。通过比较水冷结构中不同材料的温度,得到传热能力的优劣,同时考虑各种材料的许用温度,结合工艺难度及工程造价等因素对各结构进行了整体比较。计算结果显示,就传热能力而言,钨串结构最好,焊接结构次之,螺栓连接结构最差。结合造价及工艺难度等条件可以看出,钨串结构仍是目前最适用于高热负荷区域的结构,W/TZM/C 作为第一壁材料的焊接结构适用于较低热负荷的区域,螺栓连接结构在未来发展中将会逐渐被取代。 相似文献
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1 引 言
考虑非线性方程组问题:
F(x)=0, x∈Rn (1)
其中,F:Rn→Rn为连续可微的非线性映射.我们讨论大规模情形,并假设F(x)的Jacobian矩阵无法获取,或存储量太大无法承受. 相似文献
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We propose a modified thermal oxidation method in which an Al2O3 capping layer is used as an oxygen blocking layer (OBL) to form an ultrathin GeOx interracial layer, and obtain a superior Al2O3/GeOx/Ge gate stack. The GeOx interfacial layer is formed in oxidation reaction by oxygen passing through the Al2O3 OBL, in which theAl2O3 layer could restrain the oxygen diffusion and suppress the GeO desorption during thermal treatment. The thickness of the GeOx interfacial layer would dramatically decrease as the thickness of Al2O3 OBL increases, which is beneficial to achieving an ultrathin GeOx interfacial layer to satisfy the demand for small equivalent oxide thickness (EOT). In addition, the thickness of the GeOx interfacial layer has little influence on the passivation effect of the Al2O3/Ge interface. Ge (100) p-channel metal- oxide-semiconductor field-effect transistors (pMOSFETs) using the Al2O3/GeOx/Ge gate stacks exhibit excellent electrical characteristics; that is, a drain current on-off (Ionloft) ratio of above 1 104, a subthreshold slope of - 120 mV/dec, and a peak hole mobility of 265 cm2/V.s are achieved. 相似文献