广义正交码索引调制系统的性能分析

摘 要：为了提高码索引调制（code index modulation，CIM）系统的传输效率，提出了一种具有更低复杂度的单输入单输出（single input single output，SISO）的广义正交码索引调制（generalized orthogonal code index modulation，GQCIM）系统。CIM 系统使用扩频码和星座符号传输信息，但只能激活两个扩频码索引和一个调制符号。而 GQCIM 系统以一种新颖的方式克服了只激活一个调制符号的限制，同时充分利用了调制符号的正交性，增加扩频码索引以传输更多的额外信息位，提高了系统的传输效率。此外，分析了GQCIM系统的理论性能，推导了误码率性能的上界。通过蒙特卡罗仿真验证了GQCIM系统的性能，对比发现GQCIM系统的理论和仿真性能一致。而且在相同的传输效率下，结果显示GQCIM系统的性能优于同样具有正交性的调制系统，如广义码索引调制（generalized code index modulation，GCIM）系统、CIM系统、码索引调制-正交空间调制（code index modulation aided quadrature spatial modulation，CIM-QSM）系统、码索引调制-正交空间调制（code index modulation aided spatial modulation，CIM-SM）系统、脉冲索引调制（pulse index modulation，PIM）系统。     

The thermochromic characteristics of Zn-doped VO2 that were prepared by the hydrothermal and post-annealing process and their polyurethane composite films

In this paper, Zn-doped VO₂ nanoparticles have been successfully fabricated by a two-step hydrothermal-annealing process, and the thermally induced visible light transmittance enhancement of Zn-doped VO₂ has been studied for the first time. It is found that Zn-doped VO₂ not only exhibits excellent solar modulation ability (ΔT_sol = 15.27%) but also can reduce the phase transition temperature and increase the visible light transmittance after the heat-induced phase transition (ΔT_lum=+5.78%). Moreover, with the increase of Zn doping concentration, the phase transition temperature (T_c) and phase transition hysteresis (ΔT) both decrease. It is shown that the Zn-doped VO₂-PU films not only have good solar light modulation ability and properties of improving visible light transmission after phase transition, but also have good durability. The research result is of great significance for improving the visible light transmittance after phase transition and realizing the practical application of VO₂ in the field of smart windows.     

The Role of Extracellular Vesicles in the Progression of Human Neuroblastoma

The long-underestimated role of extracellular vesicles in cancer is now reconsidered worldwide by basic and clinical scientists, who recently highlighted novel and crucial activities of these moieties. Extracellular vesicles are now considered as king transporters of specific cargoes, including molecular components of parent cells, thus mediating a wide variety of cellular activities both in normal and neoplastic tissues. Here, we discuss the multifunctional activities and underlying mechanisms of extracellular vesicles in neuroblastoma, the most frequent common extra-cranial tumor in childhood. The ability of extracellular vesicles to cross-talk with different cells in the tumor microenvironment and to modulate an anti-tumor immune response, tumorigenesis, tumor growth, metastasis and drug resistance will be pinpointed in detail. The results obtained on the role of extracellular vesicles may represent a panel of suggestions potentially useful in practice, due to their involvement in the response to chemotherapy, and, moreover, their ability to predict resistance to standard therapies—all issues of clinical relevance.     

Relaxor behavior and energy storage density induced by B-sites substitutions in (Ca0.28Ba0.72)2.1Na0.8Nb5O15 Tungsten bronze ceramics

Lead-free relaxor ferroelectrics (Ca_0.28Ba_0.72)_2.1Na_0.8Nb_5-xSb_xO₁₅ (CBNNS) and (Ca_0.28Ba_0.72)_2.1Na_0.8Nb_5-yTa_yO₁₅ (CBNNT) with tungsten bronze structure were fabricated via solid-state reactions. The obtained CBNNS and CBNNT ceramics showed different dielectric behaviors. Only the CBNNS ceramics revealed an intensified diffusion and relaxor-like characteristics, which could be verified by the modified Curie–Weiss law. The relaxor behaviors in CBNNS were attributed to the radii difference between Sb⁵⁺ and Nb⁵⁺ ions co-occupying in B-sites. For the substitution of Nb⁵⁺ by Sb⁵⁺ in CBNNS ceramics, the change from macroscopic polarization to local polarization could also give rise to the obvious relaxor behavior. The Raman spectra verified a larger off-centering of the cation and a higher distortion degree for BO₆ octahedron in the ab plane for CBNNS ceramics when compared with those of CBNNT. In addition, the ferroelectric properties of CBNNS ceramics further indicated the relaxor ferroelectric nature, and also confirmed that the relaxor behavior helped to improve the energy-storage performance.     

基于单片机C8051F500的无刷直流电机控制研究

永磁无刷直流电机是近些年发展起来的一种新型电机,具有效率高、调速性能好、启动转矩大等诸多优点,在运动控制领域中的应用日趋广泛。基于电机专用控制芯片MC33035,采用单片机C8051F500为主控芯片,设计一款无刷直流电机智能控制器,实现对无刷直流电机启动停止、正反转、调速、转速显示等控制。通过简要介绍无刷直流电机工作原理,使用MATLAB/Simulink对控制系统进行建模仿真,对无刷直流电机控制系统进行软、硬件设计。实验结果表明,该控制系统运行稳定,抗干扰性强,具有良好的市场应用价值。     

The alginate fermentation strain Pantoea sp. F16-PCAi-T3P21 and ethanol production

Bio-ethanol production from algae is a promising way to help solve the energy problem. Alginate is a major component of algae, but it cannot be utilized by existing ethanol fermentation microorganisms. In order to improve the utilization rate of brown algae, high alginate fermentation strains should be obtained. In this research, strains for algae fermentation were got from several experiments. The ethanol yield of strain A was the highest, which was 0.095 g/g (ethanol to alginate). The identification of strain A was carried out and it was 99% identical to Pantoea sp. F16-PCAi-T3P21. Fermentation experiments with different substrates were carried out, such as laminaran, mannitol, L. japonica and acid hydrolysate of L. japonica, and the ethanol yield rate of L. japonica acid hydrolysate was the highest, which reached 0.17 g/g ethanol to L. japonica. It showed that strain A can converse alginate to ethanol in a relatively high yield rate, and might be a promising strain with L. japonica as the substrate, we believe more research should be carried out on this strain.     

改型Wollaston棱镜干涉光谱仪的调制度研究

改型Wollaston棱镜(MWP)无需中继,可构建微型傅里叶变换光谱仪。回顾了MWP的基本原理,从调制度定义出发,计算得到准单色光源的复相干度,找到调制度的影响因素——扩展视场、剪切结构、焦面探测等。建立一般的干涉定域分析模型后,由像点逆光路追迹给出MWP的厚度计算公式,代入调制度约束参数得到不同参量的误差容限。通过FRED记录不同视场扩展情况的灰度与辐照度,结果显示,调制度为0.9时,视场与理论估算值1.24°基本相符;不同剪切量的灰度与辐照度变化特性表明,结构角会使定域垂直系统光轴的入射角发生变化,与晶轴倾角共同影响双折射率差;2.5和8μm像元探测采样表现出调制度差异,描述了定域深度或离焦的影响。以准单色光源、复相干度表示调制度,可将不同影响因素统一至约束参数中,相关变量误差容限可作为MWP-FTS的设计依据。     

Airborne bacterial assemblage in a zero carbon building: A case study

Currently, there is little information pertaining to the airborne bacterial communities of green buildings. In this case study, the air bacterial community of a zero carbon building (ZCB) in Hong Kong was characterized by targeting the bacterial 16S rRNA gene. Bacteria associated with the outdoor environment dominated the indoor airborne bacterial assemblage, with a modest contribution from bacteria associated with human skin. Differences in overall community diversity, membership, and composition associated with short (day‐to‐day) and long‐term temporal properties were detected, which may have been driven by specific environmental genera and taxa. Furthermore, time‐decay relationships in community membership (based on unweighted UniFrac distances) and composition (based on weighted UniFrac distances) differed depending on the season and sampling location. A Bayesian source‐tracking approach further supported the importance of adjacent outdoor air bacterial assemblage in sourcing the ZCB indoor bioaerosol. Despite the unique building attributes, the ZCB microbial assemblage detected and its temporal characteristics were not dissimilar to that of conventional built environments investigated previously. Future controlled experiments and microbial assemblage investigations of other ZCBs will undoubtedly uncover additional knowledge related to how airborne bacteria in green buildings may be influenced by their distinctive architectural attributes.