强C*-代数值度量空间及其不动点定理

在C*-代数值度量空间基础上,给出强C*-代数值b-度量空间的概念,并证明了一个压缩条件下的不动点定理.做为应用,文中给出了某类算子方程中解的存在性及唯一性的判定.      

Hilbert C*-模上可共轭算子的极分解的一个注记

在Hilbert C^*-模上的可共轭算子的这个一般的框架下,给出了算子极分解的若干性质的刻画.     

Banach格上的无界绝对弱收敛的弱~*Dunford-Pettis算子

为进一步研究Banach格上算子的性质,首先,给出无界绝对弱收敛的弱~*Dunford-Pettis算子的定义.其次,通过构造不交序列,探究无界绝对弱收敛的弱~*Dunford-Pettis算子的等价刻画和控制性,并获得了相关推论.最后,研究了该算子与弱~*Dunford-Pettis算子、极限算子和紧算子间的关系.     

CMAC辨识的CMYK到CIE L*a*b*颜色空间转换模型的研究

为了解决设备相关颜色空间CMYK与设备无关颜色空间之间的相互转换问题,利用小脑模型神经网络(cerebellar model articulation controller, CMAC)高度非线性拟合能力,研究CMYK颜色空间与CIE L*a*b*之间的转换关系,研究结果显示该方法具有结构简单,易于软件和硬件的实现,将IT8.7/3标准色靶文件中104个专业色块值作为检验样本,检验样本的平均色差为1.6,完全适用于两种不同颜色空间之间的转换过程.      

Proof of inseparable prime C~*-algebras A with RR(A) = 0 being orimitive C~*-algebras

First, that prime C~* -algebras with countable primitive ideals are all primitive C~*-algebras is proved. Then the proof that prime C~* -algebras with property RR(A) = 0 are all primitive C~*-algebras is given.     

一类形变超W-代数上的超双导子及超交换映射

设■是一类形变超W-代数W■(2, 2).首先确定■上的超斜对称双导子,证明了非内导子的存在性.进一步得到■上的线性超交换映射是非标准的.     

基于A~*算法的机器人二维与三维路径规划实现

主要对移动机器人轨迹进行规划设计,将移动机器人的轨迹环境采用栅格化处理,提出了一种能结合全局和局部规划的改进的A*算法。使移动机器人在环境未知的情况下进行自主规划路径,通过MATLAB软件验证了算法的可实现性与稳定性,并将其与经典A*算法作对比,以证明改进算法的在运算能力,可实现性和稳定性上的优势。     

局部紧Lindelöf空间的序列覆盖映象

利用特定的覆盖性质，借助序列覆盖映射，建立局部紧Lindeloef空间和CS覆盖、sn覆盖、cs^＊覆盖之间的联系，以及局部紧Lindeloef空间的序列覆盖映象特征，得到并深化局部紧Lindeloef空间的一些相应结果，完善了局部紧Lindeloef空间的映射理论。     

Vegetation evolution on the central Chinese Loess Plateau since late Quaternary evidenced by elemental carbon isotopic composition

There are many controversial issues in loess studies such as natural vegetation types on the Chinese Loess Plateau during the historical periods and the spatial and temporal evolution of C3/C4 plants. Elemental carbon isotopic composition （δ^13Cec） in the loess section may offer new evidence for these problems. Elemental carbon （EC） is produced by incomplete combustion of vegetation, and its carbon isotopic composition has a very small difference from that of the formal vegetation, then δ^13Cec can be used as a record to recover the changes of vegetation. Elemental carbon was extracted by applying the oxidation method from the Ioess-paleosol sequence in the central Chinese Loess Plateau, and its car- bon isotope composition was analyzed by the isotope mass spectrometer. The results showed that the vegetation in this region was a mixed type of C3 and C4 plants, dominated with C3 plants in most of the time. Since late Quaternary, C3/C4 plants may not follow a simple glacial-interglacial cycle mode on the Chinese Loess Plateau, but showing fluctuations. C3 plants increased gradually in L4 period, and more C3 plants occurred during $3 period, and C4 plants increased again during L3-- L2 periods, after that, Cs plants dominated again during S1 --S0 periods. During periods of paleosol development, C3 plants were abundant in S3 and S1, and there were more Ca plants in S2 and SO. During periods of loess sedimen- tation, there were more C3 plants in L4 and L1, and there were more C4 plants in L3 and L2. On the orbital timescale, the vegetation variations revealed by δ^13Cec record are consistent with the results of pollen data and also similar to the results obtained by organic carbon isotopic composition since the last glacial period.     

基于A*改进算法的机械臂避障路径规划

为解决机械臂在运行时可能与工作空间中的障碍物发生碰撞,提出圆柱体包络碰撞检测法和基于A*算法的变步长分段搜索法.运用圆柱体包络碰撞检测法,将碰撞检测问题转化为计算圆柱体间的位置关系.变步长分段搜索法解决了应用传统A*算法可能出现的搜索数据量大甚至搜索死循环等问题.分别在基于OpenGL的三维仿真实验平台和实际系统中验证了该方法的有效性和可行性.     

弱c*-正规子群与有限群的p-幂零性

引入弱c*-正规子群的定义,并利用此定义得到有限群p-幂零的两组充分条件.     

A newC *-algebra and its essential commutant

A newC ^*-algebraE + E _* is established. It contains the large Hankel algebra N^G produced by all Toeplitz operators and Hankel operators. It is the proper algebra ofB(H ²) and its essential commutant is obtained, which is generated by those Toeplitz operators that have symmetric continuous function symbols and compact operators.     

Comparison of the carbon isotope composition of total organic carbon and long-chain <Emphasis Type="Italic">n</Emphasis>-alkanes from surface soils in eastern China and their significance

Surface soil samples collected over a high spatial resolution in eastern China were analyzed for carbon isotope composition （δ^13C） of total organic carbon （TOC） and higher plant-derived long-chain n-alkanes, with the latter reported as weighted mean values. The two sets of δ^13C values are significantly correlated and show similar trends in spatial variation. The spatial distribution of δ^13C shows less negative values in the mid-latitudes between 31°N and 40°N and more negative ones at higher and lower latitudes. This is consistent with previously reported carbon isotope data from surface soil phytoliths in the same region and suggests that the mid-latitude area provides relatively favorable growing condi- tions for C4 plants. Furthermore, δ^13C values of both TOC and long-chain n-alkanes from 12 surface soil samples collected from a small grassland in north China displayed similar carbon isotope values and the difference between paired δ^13C of a soil samples remains relatively constant. Our data demonstrate that in eastern China, soil δ^13C composition of both TOC and long-chain n-alkanes is effective indicators of C3/C4 ratios of the prevailing vegetation. This work suggests that -22‰ and -32‰ are good es- timated end members for the weighted mean δ^13C values of long-chain n-alkanes （C27, C29 and C31 n-alkanes） from soils under dominant C4 or C3 vegetation, allowing us to reconstruct paleovegetation trends.     

ρ*混合序列的Chover型重对数律

设{X_n,n≥1}是同分布的ρ^*混合序列, 其分布属于特征指数为α(0<α<2)的非退化稳定分布正则吸引场. 利用ρ^*混合序列的矩不等式证明了依概率1有,并获得了一系列等价条件.     

The short C-terminal hydrophilic domain of NhaH Na^＋/H^＋ antiporter from Halobacillus dabanensis with roles in resistance to salt and in pH sensing

The Na^＋/H^＋ antiporter plays key roles in maintaining low cytoplasmic NaNa^＋ level and pH homeostasis, while little is known about the Carboxyl-terminal hydrophilic tails of prokaryotic antiporters. In our previous study, the first Na^＋/H^＋ antiporter gene nhaH from moderate halophiles was cloned from Halobacillus dabanensis D-8 by functional complementation. A topological model suggested that only nine amino acid residues （^395PLIKKLGMI403） existed in the hydrophilic C-terminal domain of NhaH. The C-terminal truncated mutant of NhaH was constructed by PCR strategy and designated as nhaH△C. Salt tolerance experiment demonstrated that the deletion of hydrophilic C-terminal nine amino acid residues significantly inhibited the complementation ability of E. coil KNabc, in which three main Na^＋/H^＋ antiporters nhaA, nhaB and chaA were deleted. Everted membrane vesicles prepared from E. coil KNabc/nhaHAC decreased both Na^＋/H^＋ and Li^＋/H^＋ exchange activities of NhaH, and also resulted in an acidic shift of its pH profile for Na^＋, indicating a critical role of the short C-terminal domain of NhaH antiporter in alkali cation binding/translocation and pH sensing.     

Effect of fatty acids on polyamine contents and Na+/H+ antiport activity in PM vesicles isolated from roots of barley under salt stress

With 200 mmol/L NaCl treatment on barley cultivar “Jian 4” (Hordeum vulgare L. cv. J4) seedlings for 6 d, the contents of covalently and noncovalently conjugated polyamines (PAs) and activities of H⁺-ATPase in plasma membrane (PM) vesicles isolated from the roots decreased remarkably. Moreover, the activity of Na⁺/H⁺ antiport was detected first in PM vesicles. The results showed that the decrease in the contents of membrane phospholipid, noncovalently conjugated PAs and activity of H⁺-ATPase caused by NaCl could be restored partially by application of 1 mmol/L stearie acid (C_16:0) and linoleic acid (C_18:2), and C_18:2 was more effective than C_16:0 In addition, a reduction in the contents of covalently conjugated PAs was only reversed partially in the presence of C_18:2 Furthermore, Na⁺/H⁺ antiport activity was strengthened by exogenous C_16:0 and C_18:2 and C_18:2 was more effective than C_16:0. The correlative analysis suggested that, after application of C_16:0 and C_18:2 under salt stress, there was a significant positive correlation existing among phospholipid content, noncovalently conjugated PA levels, H⁺-ATPase activities and Na⁺/H⁺ antiport activities, indicating that one of the mitigative mechanisms of exogenous fatty acids on salt injury was to improve membrane phospholipid and PA contents, leading to an enhance in membrane integrity and a change in charge status of PM vesicles, so the activity of membrane-associated enzyme H⁺-ATPase was increased and synthesis of Na⁺/H⁺ antiport protein was activated.     

完全图Kn的{P5,C5}分解

图分解问题已在很多邻域中得到了广泛的应用。用P₅表示5个顶点的路，C₅表示5个顶点的圈，本研究讨论了完全图K_n分解成5个顶点的路P₅和圈C₅的存在性，给出完全图K_n存在{P₅,C₅}-强制分解的充分必要条件是n≥7(n≠8)，以及完全图K_n存在{P₅,C₅}-分解的充分必要条件是n≥5(n≠6)。     

具有常余维数2k+2l不动点集的(Z2)k作用

设(Z₂)^k作用作用于光滑闭流形Mⁿ, 其不动点集具有常余维数r, J^r_n,k是具有上述性质的未定向n维上协边类［Mⁿ］构成的 集合.J^r_*,k为未定向上协边环MO_*的理想. 通过构造MO_*的一组生成元证明由所有维数大于2^k+2^l的上协边类及分解式中每个因子的维数都小于2^k的2^k+2^l维可分解上协边类构成.     

二维Ti3C2Tx MXene材料的制备与工艺优化

二维（2D）过渡金属碳/氮化物（MXene）材料是当前最受关注的二维材料之一,其中二维碳化钛（Ti₃C₂T_x MXene）材料的研究最为广泛。该材料目前主要通过刻蚀三元碳化物或氮化物（MAX相）后进一步插层得到,因此MAX相材料的纯度和制备工艺条件直接决定了Ti₃C₂T_x MXene材料的物化性质。主要完成了不同Ti₃AlC₂ MAX相材料的筛选,选择氢氟酸（HF）刻蚀,并优化了不同的插层方法,制备了一系列Ti₃C₂T_x MXene材料。通过X射线衍射（XRD）、场发射扫描电镜（FESEM）、透射电子显微镜（TEM）、原子力显微镜（AFM）和X射线光电子能谱（XPS）等表征,确定使用原位锂离子（Li⁺）插层法可有效获得单层Ti₃C₂T_x MXene材料。制备的单层Ti₃C₂T_x MXene材料的表面平整,片径约为150 nm,厚度约为2 nm。同时,创新性地采用涡旋震荡辅助材料分层,极大地缩短了超声时间,提高了单层Ti₃C₂T_x MXene材料的产率（可达70%）,并且可以避免材料氧化,为Ti₃C₂T_x MXene材料未来应用提供了新方法。     

乌天麻外观性状与特征性成分含量相关性研究

为探究乌天麻(Gastrodia elata f.glauca)外观性状与特征性成分含量之间的关系,本研究通过采集贵州、陕西两地天麻主产区的乌天麻鲜品,测定其长度、宽度、厚度、质量等指标,利用电子感官仪测定样品色、气、味等性状特征值,采用高效液相色谱法测定样品中主要有效成分的含量,以进一步探究两者的相关性。结果表明,乌天麻形、色、气、味等性状特征值与其主要成分含量之间均存在一定的相关性。其中,厚度与天麻素、对羟基苯甲醇、巴利森苷类含量的关联性最强,呈正相关;颜色值a~*与天麻素含量呈极显著负相关,L~*、E~*_ab与对羟基苯甲醇含量呈显著负相关;对羟基苯甲醇含量与电子舌CTS (咸)、ANS (甜)响应值呈极显著正相关,与电子鼻LY型响应值呈显著或极显著负相关,与T型和P型响应值呈显著或极显著正相关。研究结果可为乌天麻质量评价提供参考。