茶菌人工复合菌剂构建和发酵性能分析

利用从茶菌中分离纯化的4个优势菌株构建人工复合菌剂。通过单独培养和不同复合方式培养的比较,确定菌株在茶菌发酵和菌膜形成中的作用;采用高效液相色谱、顶空固相微萃取和气相色谱-质谱联用等方法分析茶菌发酵过程中主要生化成分变化;经历多次传代接种后,采用人工分离和宏基因组分析相结合分析菌群组成和稳定性。结果表明：供试的4个菌株中,葡糖醋杆菌J5(Gluconacetobacter sp. J5)是产生纤维素和菌膜的核心菌株。混合菌株组合C3C5C6J5发酵后在菌体生长、糖利用、发酵液pH值、总酸度和茶多酚含量等指标与自然发酵相似。经历6代转接后菌群稳定,复配的菌株在人工菌群中均为优势菌株。表明从天然茶菌饮料中分离纯化功能菌株,通过菌株复配构建稳定的人工发酵剂可行,为茶菌的标准化工业生产打下基础。     

A CO and CO2 tolerating (La0.9Ca0.1)2(Ni0.75Cu0.25)O4+d Ruddlesden-Popper membrane for oxygen separation

A series of novel dense mixed conducting ceramic membranes based on K₂NiF₄-type (La_1–xCa_x)₂ (Ni_0.75Cu_0.25)O_4+δ was successfully prepared through a sol-gel route. Their chemical compatibility, oxygen permeability, CO and CO₂ tolerance, and long-term CO₂ resistance regarding phase composition and crystal structure at different atmospheres were studied. The results show that higher Ca contents in the material lead to the formation of CaCO₃. A constant oxygen permeation flux of about 0.63 mL·min⁻¹·cm⁻² at 1173 K through a 0.65 mm thick membrane was measured for (La_0.9Ca_0.1)₂ (Ni_0.75Cu_0.25)O_4+δ, using either helium or pure CO₂ as sweep gas. Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO₂ concentration. The membrane showed excellent chemical stability towards CO₂ for more than 1360 h and phase stability in presence of CO for 4 h at high temperature. In addition, this membrane did not deteriorate in a high-energy CO₂ plasma. The present work demonstrates that this (La_0.9Ca_0.1)₂(Ni_0.75Cu_0.25)O_4+δ membrane is a promising chemically robust candidate for oxygen separation applications.     

基于视角转换的多视角步态识别方法

针对步态识别中步态视角变化、步态数据样本量少及较少利用步态时间信息等问题,提出一种基于视角转换的步态识别方法.通过VTM-GAN网络,将不同视角下的步态能量图及含有步态时间信息的彩色步态能量图,统一映射到保留步态信息最丰富的侧视图视角,以此突破步态识别中多视角的限制,在视角转换的基础上,通过构建侧视图下的步态正负样本对...     

带电粒子束偏转系统像差分析的自动微分方法

根据AD技术的基本原理,研究了对带电粒子光学系统进行像差分析的AD方法,给出了偏转系统高斯光学性质及三阶几何像差系数的AD表述。利用面向对象的编程技术,在Visual C++中编制了一个软件包,实现了基本AD功能及带电粒子光学计算功能。用此软件计算了鞍型线圈磁偏转器的高斯光学性质及三阶像差,其结果具有非常高的精度,高斯光学性质的计算相对误差仅为10－１３量级甚至更低。证明AD方法对带电粒子光学系统的像差分析是极其有效的。     

Three-dimensional structure of WS2/graphene/Ni as a binder-free electrocatalytic electrode for highly effective and stable hydrogen evolution reaction

Tungsten disulfide (WS₂) has attracted much attention as the promising electrocatalyst for hydrogen evolution reaction (HER). Herein, the three-dimensional (3D) structure electrode composed of WS₂ and graphene/Ni foam has been demonstrated as the binder-free electrode for highly effective and stable HER. The overpotential of 3D WS₂/graphene/Ni is 87 mV at 10 mA cm^?2, and the current density is 119.1 mA cm^?2 at 250 mV overpotential, indicating very high HER activity. Moreover, the current density of 3D WS₂/graphene/Ni at 250 mV only decreases from 119.1 to 110.1 mA cm^?2 even after 3000 cycles, indicating a good stability. The high HER performance of 3D WS₂/graphene/Ni binder-free electrode is superior than mostly previously reported WS₂-based catalysts, which is attributed to the unique graphene-based porous and conductive 3D structure, the high loading of WS₂ catalysts and the robust contact between WS₂ and 3D graphene/Ni backbones. This work is expected to be beneficial to the fundamental understanding of both the electrocatalytic mechanisms and, more significantly, the potential applications in hydrogen economy for WS₂.     

轴外压作用下复合材料网格加筋柱壳蒙皮铺层和筋条角度优化分析

采用Nelder-Mead单纯形优化方法,以均匀分布或二项分布随机数作为初始寻优点,对复合材料网格加筋柱壳在轴、外压载荷作用下的蒙皮铺层方向和筋条角度进行了优化分析.通过比较筋条优化、蒙皮优化和筋条、蒙皮同时优化的变化,发现筋条角度是结构承载能力的主要影响因素,优化的筋条角度可提高临界载荷20%～50%,均衡对称蒙皮铺层加筋壳接近于最优结构.优化设计可在均衡对称蒙皮铺层的基础上只对筋条角度进行分析,与最优结构的差别在5%以内.轴压优化筋条角度在30°左右,外压优化筋条角度在65°左右.     

在-55~125℃范围内误差小于±0.3℃硅基温度传感器

提出了基于寄生参数自校正的高精度温度传感器,并给出了基于CSMC 0.5μm混合信号CMOS工艺的仿真结果.利用CMOS工艺衬底pnp三极管的发射区-基区pn结作为温度传感单元,提出了易于开关-电容电路实现的寄生电阻校正方法,消除了基区电阻非线性对温度测量的影响,提高了测量精度.电路仿真结果显示,系统测温误差在-55℃～125℃范围内仅为±0.3℃.     

Fabrication and characterization of SmO_（0.7）F_（0.2）FeAs bulk with a transition temperature of 56.5 K

The superconductivity of iron-based superconductor SmO 0.7 F 0.2 FeAs was investigated. The SmO 0.7 F 0.2 FeAs sample was prepared by the two-step solid-state reaction method. The onset resistivity transition temperature is as high as 56.5 K. X-ray diffraction (XRD) results show that the lattice parameters a and c are 0.39261 and 0.84751 nm, respectively. Furthermore, the global J c was more than 2.3 × 10 5 A/cm 2 at T = 10 K and H = 9 T, which was calculated by the formula of J c = 20ΔM/[a(1-a/(3b))]. The upper critical fields, H c2 ≈ 256 T (T = 0 K), was determined according to the Werthamer-Helfand-Hohenberg formula, indicating that the SmO 0.7 F 0.2 FeAs was a superconductor with a very promising application.     

基于期权博弈理论的EPC项目投资决策研究

政府补贴金额对EMCo投资EPC项目产生的影响是一个值得研究的问题。本文以电力EPC项目的投资决策过程为研究对象,以政府的灵活补贴政策为依据,结合期权博弈模型,构建不确定情况下EPC项目的对称双头垄断投资模型,并在模型中设置价值匹配和平滑条件,研究了投资EPC项目过程中政府补贴对EMCo的影响,获得了EMCo签订节能服务合同的最优阈值和补贴数值及政府补贴的均衡策略,为电力EPC项目的投资决策提供了可靠依据。