倒立摆系统的鲁棒H_∞控制及仿真

倒立摆系统是一个复杂的、非线性的、不确定的高阶自然不稳定系统,是学习控制理论课程和进行各种控制实验的典型实验平台,是研究各种控制理论的理想受控对象,具有重要的理论研究价值.针对倒立摆参数不确定性的问题,应用线性矩阵不等式方法设计H∞状态反馈控制器对倒立摆平衡系统进行控制.对系统进行仿真的结果表明,在系统参数不确定的情况下,H∞控制方法比模糊控制方法更加有效.     

空时分组码在时变衰落信道中的性能

从实用性出发,对空时分组码在时变衰落信道中的性能进行了研究.采用SIMULINK仿真工具构造了时变衰落信道的仿真模型,模型由信道、发射端和接收端组成:信道部分由多径Rayleigh信道和高斯白噪声构成;发射端由信源、串并转换器、调制器、空时分组编码器和功率分配模块构成;接收端由信号合并、最大似然译码器、调制解调器和误比特率计算模块组成.仿真结果表明:在平坦慢衰落信道中,STTD性能比单收发系统的性能有很大提高,并且随着SNR的增大,STTD性能的提高幅度增大;在平坦时变衰落信道中,随着最大多普勒频移的增大,STTD性能有所下降,尤其是在大信噪比条件下,性能下降得更明显.     

偶图Kn，n＋8-A（｜A｜≤3）的圈长分布唯一性

阶为n的图G的圈长分布是序列（c1，c2，…，cn），其中ci是图G中长为i的圈数．设A真包含E（Kn,n＋8），在情况①G=Kn,n＋8（n≥13）；②G=Kn,n＋8-A（｜A｜=1，n≥15）；③G=Kn,n＋8-A（｜A｜=2，n≥17）；④G=Kn,n＋8-A（｜A｜=3，n≥19）时，图G由其圈长分布唯一确定．     

Non-marine Jurassic rocks of Thailand: A summary

Non-marine Jurassic rocks are widespread in the northeastern part (Khorat Plateau), and partly in the northern, eastern, and southern parts of Thailand. In the Khorat Plateau, the rocks, more than 1000 m thick, are represented by the Phu Kradung and Phra Wihan Formations of the Khorat Group but are less extensive in the north, east, and south. Reddish brown to grayish purple sandstones, siltstones, claystones, conglomeratic sandstones and conglomerates are the main lithologies; calcrete nodules are also present in claystones only in the Phu Kradung Formation. Deposition occurred mostly in meandering and braided rivers in semi-arid and slightly humid conditions for the Phu Kradung and Phra Wihan Formations, respectively, except for the southern rocks, where lacustrine deposits dominate. Age determinations are based mainly on vertebrates, bivalves and palynomorphs indicating reassignment to the Jurassicpossibly Early Cretaceous.     

Jurassic-Cretaceous boundary in northeastern China: placement based on buchiid bivalves and dinoflagellate cysts

Global environments changed greatly during the Late Jurassic and Early Cretaceous, particularly during the Jurassic-Cretaceous boundary interval. Separation of the world into Tethyan, Boreal and other biogeographic realms complicates international correlation, and even the pelagic ammonites cannot play their characteristic role of principle correlation criteria. In the Boreal and North Pacific realms, the Late Jurassic and Cretaceous buchiid bivalve zones have very good calibration to Boreal ammonite zones, which, in turn, have approximate correlations to Tethyan ammonite zones. Therefore, buchiid bivalves provide a means to identify Upper Jurassic-Lower Cretaceous stages and the Jurassic-Cretaceous boundary interval. The base of the Buchia unschensis Zone is roughly coincident with the Boreal ammonite Craspedites exoticus subzone, Upper Volgian Craspedites okensis Zone, which in turn closely corresponds to the base of the Tethyan ammonite basal Berriasian Berriasella jacobi Zone. The top of the underlying Buchia russiensis Zone approximately coincides with that of the uppermost Middle Volgian, Boreal ammonite Epivirgatites variabilis Zone, which approximately corresponds to the Tethyan ammonite Durangites Zone of uppermost Tithonian. Buchia and dinoflagellate cyst assemblages from two regions in eastern Heilongjiang of northeastern China indicate the presence of the Jurassic-Cretaceous boundary interval. The Dong’anzhen Formation of Dong’an, Raohe County contains Middle Volgian-Lower Valanginian Buchia assemblages and the Jurassic-Cretaceous boundary is tentatively assigned to either the base of the Buchia fischeriana-Buchia unschensis assemblage or between the Buchia fischeriana-Buchia unschensis and Buchia russiensis-Buchia fischeriana assemblages. The Dongrong Formation from boreholes at Suibin, Suibin County, yields uppermost Oxfordian to basal Berriasian Buchia assemblages and Oxfordian-Barremian dinoflagellate cyst assemblages. Here, the Jurassic-Cretaceous boundary interval is probably between the Buchia cf. mosquensis-Buchia cf. rugosa assemblage (including Buchia ex gr. russiensis and Buchia ex gr. taimyrensis) and the overlying non-Buchia-bearing deposits.     

山茶科珍稀濒危植物圆籽荷的繁殖生物学研究

圆籽荷是中国特有的单种属稀有植物,历年来对其研究较少.对圆籽荷的分布现状,生境,有性生殖过程,种子散布等进行了观察分析,结果显示,在自然条件下,圆籽荷主要以有性生殖为主,能正常地开花结实,同时在一些环境下存在着分蘖方式的营养繁殖;圆籽荷为严格的异花授粉植物,昆虫主要为蜂类起重要的传粉作用,种子主要靠重力散布.     

基于噪声检测的多语言知识图谱实体对齐技术研究

针对在实体对齐任务中,由于缺少噪音实体对的标记,导致对齐准确率不高的问题,提出采用健壮性实体对齐(Robust Entity Alignment,REA)方法,设计了噪声感知实体对齐模块和噪声检测模块.首先,噪声感知实体对齐模块是基于图卷积神经网络(Graph Convolutional Networks,GCN)的知识图编码器,将知识图谱中的实体对更新嵌入;然后,基于生成对抗网络(Generative Adversarial Networks,GAN)设计了噪声生成器和噪声鉴别器,从而将实体对中的噪音实体对区分出来;最后,通过一种交互的强化训练策略,迭代使噪声感知和实体对齐相结合.实验结果表明,在DBP15K数据集上测试,新方法能有效提高在涉及噪音情况下的实体对齐精准度,与GCN-Align和IPTransE这些基准嵌入模型相比,Hits@1、Hits@5、M_RR 3个评价指标上均有较大的提升.     

大鼠灌胃中国蜂胶醇提物后血浆中5种酚酸类成分的HPLC测定及其药代动力学

对大鼠灌胃蜂胶乙醇提取物(EEP)后,血浆中5种酚酸类成分的药代动力学特性进行研究.用HPLC-UV法测定血浆中咖啡酸、香豆酸、阿魏酸、异阿魏酸和3,4-二甲氧基肉桂酸的浓度.应用WinNonlin非典型房室模型计算软件计算相应的药代动力学参数.血浆中内源性物质和内标对酚酸类成分测定无干扰,回收率、准确度及日内、日间精密度均符合生物样品测定要求.结果表明,该方法简便、快速、重复性好,适用于咖啡酸等5种蜂胶中酚酸类成分的大鼠血药质量浓度测定及体内药动学研究.     

氨式碳酸铜溶液中铜离子含量的测定方法

针对传统铜离子含量测定方法在氨式碳酸铜溶液中铜离子含量测定过程中所存在的问题,考察影响氨式碳酸铜溶液中铜离子含量测量结果的测定条件,明确其影响机理,对传统测定方法进行改进,并用质量法对该方法的准确性进行验证.结果表明:改进的测定方法与传统方法相比具有准确性高、简便、快速等优点.     

浅谈实践教学对本科生能力培养的作用及存在问题

实最教学是本科教育的重要组成部分之一,实践教学在本科生能力培养过程中具有重要的作用和意义,该文以什么是实最教学、实最教学的具体内容及特点为出发点,着重阐述了实践教学对本科生能力培养作用及其在高等教育中的地位,初步剖析了实践教学在高等教育中存在的问题,以期进一步深化实践教学改革,提高实践教学质量。