Ultra-high energy cosmic rays threshold in Randers-Finsler space

Kinematics in Finsler space is used to study the propagation of ultra high energy cosmic rays particles through the cosmic microwave background radiation. We find that the GZK threshold is lifted dramatically in Randers-Finsler space. A tiny deformation of spacetime from Minkowskian to Finslerian allows more ultra-high energy cosmic rays particles to arrive at the earth. It is suggested that the lower bound of particle mass is related with the negative second invariant speed in Randers-Finsler space.     

Finslerian Perturbation for the ACDM Model

We present Finslerian perturbation for the ∧CDM model, which breaks the isotropic symmetry of the universe. The analysis on the Killing vectors shows that the Randers-Finsler spacetime breaks the isotropic symmetry even ff the scalar perturbations of the FRW metric vanish. In Randers-Finsler spacetime, the modified geodesic equation deduces a modified Boltzmann equation. We propose a perturbational version of the gravitational field equation in Randers-Finsler spacetime, where we have omitted the curvature tensor that does not belong to the base space of the tangent bundle. The gravitational field equations for the gravitational wave are also presented. The primordial power spectrum of the gravitational wave is investigated. We show that the primordial power spectrum for super-horizon perturbations is unchanged. For sub-horizon perturbations, however, the power spectrum is modified.     

A Matter Dominated Navigation Universe in Accordance with the Type Ia Supernova Data

We investigate a matter dominated navigation cosmological model.The influence of a possible drift(wind) in the navigation cosmological model makes the spacetime geometry change from Riemannian to Finslerian.The evolution of the Finslerian Universe is governed by the same gravitational field equation with the familiar Friedmann-Robertson-Walker one.However,the change of space geometry from Riemannian to Finslerian supplies us a new relation between the luminosity distant and redshift.It is shown that the Hubble diagram based on this new relation could account for the observations on distant Type Ia supernovae.     

导电聚间甲基苯胺空心微球的制备及表征

在无任何掺杂酸的条件下,以过硫酸铵(APS)既为氧化剂、又为掺杂剂,采用无模板(template-free)自组装的方法制备了导电聚间甲基苯胺(PMT)空心微球.该空心微球的平均直径约为2μm,壳的厚度约为140nm.研究表明PMT空心微球是以球状的间甲苯胺胶束为软模板(soft-template)经过自组装过程而形成的.借助FTIR、UV-Vis和XRD等结构表征证实自组装的空心微球为导电态的聚间甲基苯胺.     

聚(3,4-乙撑二氧噻吩)导电织物的制备、结构及其电致变色性能

本文采用原位聚合法, 以耐酸性好的涤纶为基底, 制得了聚(3,4-乙撑二氧噻吩)/涤纶复合导电织物[Poly(3,4-ethylenedioxythiophene)/conducting terylene textile, PEDOT/CTT], 分析了该导电织物的形貌、导电性能及结构, 并对其电致变色性能进行了初步测试. 实验结果表明, 所得到的PEDOT/CTT具有良好的导电性和一定的电致变色性能, 有望在全固态电致变色织物的制备中获得应用.     

稀土钨青铜K0.71Nd0.028WO3的制备及其电性能

Tetragonal tungsten bronze K_0.71Nd_0.028WO₃ was synthesized by rare earth co-permeation method using Keggin type POMs of α-K₁₀[SiCu₃(OH₂)W₉O₃₇]·6H₂O (abbreviated as SiW₉Cu₃) as precursor. XRD, XPS, XRF, TG-DTA were used to characterize the resulting material. The XPS results indicate that Nd has permeated and diffused into the body of the sample and exists in tungsten bronze in the form of K_0.71Nd_0.028WO₃. The results of TG-DTA show that K_0.71Nd_0.028WO₃ begins to decompose at 320 ℃. The consequence of DC four-probe shows that the conductivity of the sample permeated by rare earth is 10³ times higher than that of the sample only permeated by methanol at room temperature. The conductivity of the sample only permeated by methanol is only 10^-3 S·cm^-1 but the conductivity of the sample permeated by rare earth is 1.65 S·cm^-1.     

PEDOT-PSS/Co-Fe_3O_4/PVA电磁功能复合纤维结构与性能

将化学共沉淀法合成的Co掺杂的Fe_3O_4(Co-Fe_3O_4)磁性粒子和化学氧化法合成的聚苯乙烯磺酸钠(PSS)掺杂的聚(3,4-乙撑二氧噻吩)(PEDOT-PSS)与聚乙烯醇(PVA)混合制备复合纺丝原液,然后经过湿法纺丝得到具有电、磁性能的PEDOT-PSS/Co-Fe_3O_4/PVA复合纤维.通过SEM、FTIR、XRD、TG、VSM以及电导率和机械性能的测试研究了不同牵伸倍率对复合纤维的结构和性能的影响.结果表明,随着牵伸倍率的增加,复合纤维的结晶性能、热稳定性能和机械性能都有所提升,其电导率则成倍增加,而其饱和磁化强度(M_s)则变化不大,约为1.7 A·m~2/kg.当牵伸倍数为4倍时,复合纤维的电导率可达到2.3 S/cm.     

Local probes strongly favor ΛCDM against power-law and R_h=ct universe

We constrain three cosmological models – the concordance cold dark matter plus cosmological constant(ΛCDM) model, the power-law(PL) model, and the Rh =ct model – using the available local probes, which include the JLA compilation of type-Ia supernovae(SNe Ia), the direct measurement of the Hubble constant(H_(z)), and the baryon acoustic oscillations(BAO). For the ΛCDM model, we consider two different cases, i.e. zero and non-zero spatial curvature. We find that by using the JLA alone, the ΛCDM and PL models are indistinguishable, but the Rh =ct model is strongly disfavored. If we combine JLA+H_(z), the ΛCDM model is strongly favored over the other two models. The combination of all three datasets supports ΛCDM as the best model. We also use the low-redshift(z 0.2) data to constrain the deceleration parameter using the cosmography method, and find that only the ΛCDM model is consistent with cosmography. However, there is no strong evidence to distinguish between flat and non-flatΛCDM models by using the local data alone.     

石墨烯折角场发射特性

针对直立的石墨烯边沿悬挂键易吸附气体分子,影响发射稳定性的问题,本文将石墨烯转移到墙状绝缘结构上,获得石墨烯折角.结合电感耦合等离子体刻蚀和湿法腐蚀法在硅衬底上制得墙状绝缘结构,以石墨烯折角作为场发射尖端,测试研究了石墨烯折角的场发射特性和石墨烯中内导电流对场发射的影响.结果表明:石墨烯折角的场发射开启场强为9.6V/μm;在2 000V阳极电压下,当石墨烯两端偏压从0V增加到10V时,场发射电流从4.5μA增加到15μA.     

基于光纤旋转连接器的光纤耦合效率研究

基于渐变折射率透镜准直器一定程度上可以提高空间光-光纤耦合效率,但会引入光纤与渐变折射率透镜装配误差和渐变折射率透镜间位置误差。鉴于以上两种误差情况,本文提出了修正光纤与渐变折射率透镜装配误差的位移法和基于楔形棱镜和平板玻璃的光束指向调整法。首先运用光线传输矩阵的数学分析方法建立了光线传输模型,分析当光纤与渐变折射率透镜存在距离误差和位置误差下耦合效率的变化,最后利用位移法降低了距离误差对插入损耗的影响,使系统插入损耗降低至0.2 dB。在存在位置误差下利用光束指向调整法降低插入损耗至0.7 dB。这两种方法可以有效提升光纤旋转连接器耦合效率。