碳团簇型雷达隐身涂料环境稳定性研究

平面环状碳团簇是一种特殊的大分子,利用其转动能级跃迁的谱线富集于1～20 GHz的微波区的特性,研究了碳团簇型隐身涂料的吸收性能稳定性及其机械特性,结果表明,该隐身涂料基本满足吸波材料的技术要求,是一种实用型的隐身材料.     

平面环状碳团簇Cn(n=6,10,13,24)振转能谱特性研究

采用密度泛函DFT中的B3P86方法,选用6-311g**基组,对平面环状碳团簇Cn(n=6,10,13,24)的振转能级特性进行了研究.结果表明,碳团簇环状结构的转动能谱恰好处于微波区域,且随碳环面积增大而向低频方向移动.同时对环状碳团簇Cn的能级分布,最高占据轨道HOMO,最低空轨道LUMO及能隙HLGs进行了研究.最后指出,利用环状碳团簇转动能谱位于微波区域的特性,设计出具有低频吸收功能的新型吸波和电磁屏蔽材料.     

宽频带碳团簇型吸波涂层的制备与性能

为满足对吸波涂层薄、轻、宽的要求,通过吸波涂层的优化设计,制备了密度较低的宽频带碳团簇型吸波涂层.该涂层为三层结构,总厚度为2.10 mm,在8～12.4GHz频率范围内,对微波的最小反射率为-42dB,其中反射率小于-10dB的工作频带达90%以上,且性能稳定,有较好的实用前景.     

碳团簇型微波隐身功能材料的研究

本文简要报道了制备温度，试样厚度，材料层数和掺杂等因素对碳团簇型功能材料的微波身性能影响的实验结果。     

新型碳团簇HI的微波低透射率性能研究

文中主要研究了新型碳团簇ＨＩ在低频率１．５～３．５ＧＨｚ之间的微波透射性能，及其温度对微波透射性能的影响，得到了具有低透射率的新型碳团簇ＨＩ的制备条件。     

热固化剂浓度对SiCN陶瓷压阻效应的影响

采用聚合物前驱体热解法制备四种加入不同热固化剂浓度的SiCN陶瓷并研究了它们的压阻效应.研究发现,热固化剂浓度对材料的电导率和压阻效应都有很大影响,只有加入适量浓度的热固化剂才会使SiCN陶瓷具有高的电导率和明显的压阻效应.借助拉曼光谱获得了材料中碳团簇的信息,进而用渗流-遂穿导电模型解释了材料的压阻行为,SiCN陶瓷的压阻特性由材料中自由碳团簇的含量和分布决定,而碳团簇的形成则由热固化剂浓度决定. 关键词： SiCN 压阻效应 热固化剂     

吸波材料研究现状及碳团簇型吸波材料设计

简要介绍了铁氧体吸波材料,手性材料,金属微粉吸波材料,导电高聚物材料,多晶铁纤维材料,纳米材料和智能隐身材料的研究和应用现状.并根据吸波材料工作原理,进行碳团簇型吸波材料实验研究,结果显示,所制样品有很好的吸波性能,在总厚度为2.11 mm的情况下,在8.2～12.4 GHz频带内,最大反射衰减可达-29dB,有效频宽占总带宽的100%,基本达到实用水平.     

GaC_n/GaC_n~+/GaC_n~-(n=1-10)团簇磁性和极化率的理论研究

本文中我们采用密度泛函理论(DFT)的B3LYP方法,在6-311+G*和LANL2DZ水平上对碳基混合团簇GaC_n/GaC_n~+/GaC_n~-(n=1-10)的磁性和极化率进行了研究,计算结果发现,除了GaC_2/GaC_2~+/GaC_2~-以外,这一系列团簇的基态构型是Ga原子位于碳链的末端的直线型.对系列团簇基态的磁性进行了分析,得到的结果是:对于中性团簇,其磁矩是随着团簇尺寸的增加而单调减小,阳离子和阴离子团簇的磁矩都随团簇尺寸的增加呈现出明显的奇偶振荡,但阳离子是奇弱偶强,而阴离子团簇则是奇强偶弱.本文还研究了系列团簇的极化率,三种类型团簇的极化率张量的平均值和各向异性不变量都表现出基本相同的规律,都是随着团簇尺寸的增大而增大.     

Si_n团簇/石墨烯(n≤6)结构稳定性和储锂性能的第一性原理计算

目前,硅/碳复合材料是锂离子电池最有潜在应用前景的高容量负极材料之一,硅与碳材料的界面状态是影响其电化学性能的重要因素.本文在作为碳材料结构单元的石墨烯表面构建了 Si_n(n≤6)团簇,采用基于密度泛函理论(DFT)的第一性原理方法研究了 Si_n团簇/石墨烯(Si_n/Gr)的几何构型、结构稳定性和电子性质.结果表明,当Si原子数n≤4时,Si_n团簇优先以平行于石墨烯的二维构型沉积在石墨烯表面,当n ≥ 5时,Si_n团簇优先以三维立体构型沉积在石墨烯表面.随着n的增大,Si_n团簇在石墨烯表面的热力学稳定性显著降低,两者之间的界面结合减弱,并且伴随着Si_n团簇与石墨烯之间的电荷转移也越来越少.同时还研究了Si_n/Gr复合构型的储锂能力,Li原子主要存储在Si_n团簇临近的石墨烯表面和Si_n团簇周围,Si_n团簇与石墨烯复合形成的协同作用增强了 Li原子吸附的热力学稳定性.当n≤4时,存储2个Li原子有利于提高xLiSi_n/Gr体系的热力学稳定性,继续增加Li原子数x会导致稳定性降低;当n≥5时,稳定性随着Li原子数x的增多而逐渐降低.     

金属原子团簇与碳原子团簇的电子能谱与吸收光谱

此文从理论上阐明，金属原子团簇与具有π电子的碳原子团簇，其公有化电子不能视为无限自由的，而是肥边界约束的，因而其电子能谱不是连续能带，而具有分裂级的特性。因此，它们的共有化电子可吸收光子由低能级跃迁到高能级而具有吸光的特性。电子能级之间的间距视团簇的大小不同而有差异，调整团簇的大小，可吸收不同波长的光。利用这种特性，可设计所需要的红外与微波吸收材料，此文提出了这方面的新理论和设计原理。     

关于"太阳在银河系中所受引力与到银心距离r的关系"的讨论

讨论了银道面内的引力场强分布和太阳在银河系中所受引力与到银心距离r的关系，指出引力场强g并不是与r的平方成反比，这是由于银河系的大小和形状不能忽略造成的．强调了万有引力定律的适用条件．     

On the predictability of the positions of the convergence zones in the ocean

The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized.     

On the calculation of the bremsstrahlung in the region of the plasma frequency

On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given.     

Dependence of the Intensity of the Spectral Lines and the Composition of the Sample and the Plasma Parameters of the Unipolar Arc

The investigation was made of the dependence of the intensity of Tl, Ga, Mo, Mg, Mn, Sn, Bi, Ni, Zn, Pt and Au spectral lines and the plasma parameters (temperature T, electron concentration n_e, degree of 6 ionnization α) from concentration of lithium additive.     

Extracting the wavefunction of the LSP at the LHC

We consider associated production of squarks and gluinos with the lightest supersymmetric particle (LSP), or states nearly degenerate in mass with it. Though sub-dominant to pair production of color SU(3)-charged superpartners, these processes are directly sensitive to the wavefunction composition of the lightest neutralinos. Exploiting event-shape variables - including some introduced here for the first time - we are able to identify the composition of the LSP by selecting events involving a single high-pT jet recoiling against missing transverse energy. We illustrate the proposed technique on a set of benchmark cases and propose methods for applying these results in more realistic experimental environments.     

Set the controls for the heart of the Sun

In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required.     

On the Question of the Source of the Apokamp

Technical Physics - The object of this work is the apokamp—a new type of plasma jet, which is formed from a bright offshoot emerging at the bending point of a channel of a high-voltage...