杨万里馆驿诗的特色

在文官体制下,宋代的官员需要频繁出行。杨万里为官多年,任职多地,在其宦游过程中,创作了一批反映馆驿行役生活的诗歌。其中有客居之思,有追程之叹,亦多赏景之情。这些诗歌内容丰富、构思独特、用语巧妙,突破了宋代一般馆驿诗诗意枯淡、情绪低沉的创作倾向,不但体现了诗人的独特诗风,一定程度上代表了南宋馆驿诗的新气象。

Performance analysis of two EM-based measurement bias estimation processes for tracking systems

In target tracking, the measurements collected by sensors can be biased in some real scenarios, e.g., due to systematic error. To accurately estimate the target trajectory, it is essential that the measurement bias be identified in the first place. We investigate the iterative bias estimation process based on the expectation-maximization（EM）algorithm, for cases where sufficiently large numbers of measurements are at hand. With the assistance of extended Kalman filtering and smoothing, we derive two EM estimation processes to estimate the measurement bias which is formulated as a random variable in one state-space model and a constant value in another. More importantly,we theoretically derive the global convergence result of the EM-based measurement bias estimation and reveal the link between the two proposed EM estimation processes in the respective state-space models. It is found that the bias estimate in the second state-space model is more accurate and of less complexity. Furthermore, the EM-based iterative estimation converges faster in the second state-space model than in the first one. As a byproduct, the target trajectory can be simultaneously estimated with the measurement bias, after processing a batch of measurements.These results are confirmed by our simulations.

A New Solution to the Hirota–Satsuma Coupled KdV Equations by the Dressing Method

The Hirota-Satsuma coupled KdV equations associated 2 x 2 matrix spectral problem is discussed by the dressing method, which is based on the factorization of integral operator on a line into a product of two Volterra integral operators. A new solution is obtained by choosing special kernel of integral operator.

A tracing of the fractional temperature field

This paper is devoted to a study of L^q-tracing of the fractional temperature field u(t, x)—the weak solution of the fractional heat equation(?_t +(-?_x)~α)u(t, x) = g(t, x) in L^p(R_+^(1+n)) subject to the initial temperature u(0, x) = f(x) in L^p(R^n).

TRACKING ERROR REDUCTION IN CNC MACHINING BY RESHAPING THE KINEMATIC TRAJECTORY

In this paper,a method of reducing the tracking error in CNC machining is proposed.The structured neural network is used to approximate the discontinuous friction in CNC machining,which has jump points and uncertainties.With the estimated nonlinear friction function,the reshaped trajectory can be computed from the desired one by solving a second order ODE such that when the reshaped trajectory is fed into the CNC controller,the output is the desired trajectory and the tracking error is eliminated in certain sense.The proposed reshape method is also shown to be robust with respect to certain parameters of the dynamic system.

Thermal energy harvesting circuit with maximum power point tracking control for self-powered sensor node applications

We present a simple implementation of a thermal energy harvesting circuit with the maximum power point tracking（MPPT） control for self-powered miniature-sized sensor nodes. Complex start-up circuitry and direct current to direct current（DC-DC） boost converters are not required, because the output voltage of targeted thermoelectric generator（TEG） devices is high enough to drive the load applications directly. The circuit operates in the active/asleep mode to overcome the power mismatch between TEG devices and load applications. The proposed circuit was implemented using a 0.35-μm complementary metal-oxide semiconductor（CMOS） process. Experimental results confirmed correct circuit operation and demonstrated the performance of the MPPT scheme. The circuit achieved a peak power efficiency of 95.5% and an MPPT accuracy of higher than 99%.

Three-dimensional microstructure simulation of Ni-based superalloy investment castings

An integrated macro and micro multi-scale model for the three-dimensional microstructure simulation of Ni-based superalloy investment castings was developed, and applied to industrial castings to investigate grain evolution during solidification. A ray tracing method was used to deal with the complex heat radiation transfer. The rnicrostructure evolution was simulated based on the Modified Cellular Automaton method, which was coupled with three-dimensional nested macro and micro grids. Experi- ments for Ni-based superalloy turbine wheel investment casting were carried out, which showed a good correspondence with the simulated results. It is indicated that the proposed model is able to predict the microstructure of the casting precisely, which provides a tool for the optimizing process.

Realization of a non-markov chain in a single 2D mineral RRAM

The non-Markov process exists widely in thermodymanic process,while it usually requires the packing of many transistors and memories with great system complexity in a traditional device structure to minic such functions.Two-dimensional(2D)material-based resistive random access memory(RRAM)devices have the potential for next-generation computing systems with much-reduced complexity.Here,we achieve a non-Markov chain in an individual RRAM device based on 2D mineral material mica with a vertical metal/mica/metal structure.We find that the potassium ions(K+)in 2D mica gradually move in the direction of the applied electric field,making the initially insulating mica conductive.The accumulation of K+is changed by an electric field,and the 2D-mica RRAM has both single and double memory windows,a high on/off ratio,decent stability,and repeatability.This is the first time a non-Markov chain process has been established in a single RRAM,in which the movement of K+is dependent on the stimulated voltage as well as their past states.This work not only uncovers an intrinsic inner ionic conductivity of 2D mica,but also opens the door for the production of such RRAM devices with numerous functions and applications.