摘要：We constructed a single C-Bézier curve with a shape parameter for G2 joining two circular arcs. It was shown that an S-shaped transition curve, which is able to manage a broader scope about two circle radii than the Bézier curves, has no curvature extrema, while a C-shaped transition curve has a single curvature extremum. Regarding the two kinds of curves, specific algo- rithms were presented in detail, strict mathematical proofs were given, and the effectiveness of the method was shown by examples. This method has the following three advantages: (1) the pattern is unified; (2) the parameter able to adjust the shape of the tran- sition curve is available; (3) the transition curve is only a single segment, and the algorithm can be formulated as a low order equation to be solved for its positive root. These advantages make the method simple and easy to implement.

摘要：A stochastic optimal control strategy for partially observable nonlinear quasi Hamiltonian systems is proposed. The optimal control forces consist of two parts. The first part is determined by the conditions under which the stochastic optimal control problem of a partially observable nonlinear system is converted into that of a completely observable linear system. The second part is determined by solving the dynamical programming equation derived by applying the stochastic averaging method and stochastic dynamical programming principle to the completely observable linear control system. The response of the optimally controlled quasi Hamiltonian system is predicted by solving the averaged Fokker-Planck-Kolmogorov equation associated with the optimally controlled completely observable linear system and solving the Riccati equation for the estimated error of system states. An example is given to illustrate the procedure and effectiveness of the proposed control strategy.

摘要：研发的超快电子衍射系统由超快电子枪、样品室、超快读出系统、电源系统,以及真空系统等组成,该超快电子衍射系统具有较高的时间分辩能力和较强的探测能力.光电阴极是蒸镀于MgFB2窗上的35 nm的银膜,该阴极对266 nm的紫外光比较敏感,有较高的量子效率,又具有很好的化学稳定性.用短磁聚焦系统来实现对光电子的聚焦,有两对偏转板,其中的一对在测量时间脉宽时用作扫描板.用双MCP探测器来增强电子图像的强度,其增益在104以上,具有单电子探测能力.系统的总时间脉宽设计为358 fs .

摘要：针对数字音频领域16bit精度、20kHz带宽的设计要求,以0.18μmCMOS工艺设计二阶单环的一位sigma-delta调制器,过采样率达256,采样频率达10.24MHz.调制器采用了全差分结构,由基于开关电容的积分器、时钟产生器及比较器等组成.仿真结果显示,该调制器的信噪失真比达94dB,动态范围达99dB.在1.8V电源电压下,整个系统的功耗为7.6mW.

摘要：主要以提高求解马尔可夫决策问题的实时动态规划(real-time dynamic programming,简称RTDP)算法的效率为目的.对几类典型的实时动态规划算法所使用的收敛判据进行了对比分析,并利用值函数上界、下界给出了称为最优行动判据的收敛判据,以及一个更适合实时算法的分支选择策略.最优行动判据可以更早地标定当前状态满足精度要求的最优行动供立即执行,而新的分支选择策略可以加快这一判据的满足.据此设计了一种有界增量实时动态规划(bounded incremental RTDP,简称BI-RTDP)算法.在两种典型仿真实时环境的实验中,BI-RTDP均显示出优于现有相关算法的实时性能.

摘要：探讨了内蒙古地区太阳总辐射月均值与日照百分率的关系,基于5个气象站1996—1998年连续3 a的月日照时数(n)和太阳总辐射值(R_s)。计算得到Angstrom方程的系数a和b,与和清华等拟合得到的中国西部太阳总辐射公式中的a=0.185,b=0.595,比较一致。同时,R_s和n之间的直接线性关系,R与月平均温度(T)之间的直接线性关系也能用来估算太阳总辐射月均值,总均方根误差约为80 MJ·m^(-2)/month,总百分比误差约为18%。