森林资源动态预测的理论与方法

在用一维Kalman滤波研究森林资源动态基础上,介绍了二维Kalman滤波的原理与方法,并以浙江省丽水市森林资源连续清查样地的地理坐标建立二维坐标系,以样地森林面积和森林蓄积为状态向量,应用二维Kalman滤波研究森林资源动态。结果表明：对森林蓄积动态及样地个数较多、面积较大的用材林和防护林的面积动态预测效果良好,而对于样地个数较少、变异系数较大的样地如特用林和未成林造林林地的面积动态预测误差较大,如要作准确预测,则需要加大这些样地的抽样个数。     

Complete rate equation modelling of quantum cascade lasers for the analysis of temperature effects

The effect of temperature on the dynamics of a GaAs-based quantum cascade laser (QCL) is analysed using a complete rate equation model. The analytical expressions for the threshold current density and the output power are derived using the model and the thermal behaviour of these parameters is examined. A better conformity of the threshold current density with experiment at higher temperatures is achieved. The effect of temperature on the 3 dB optical bandwidth is further investigated using the same model. A comparative analysis of the model is performed with the recently reported rate equation models. It is observed that the 3 dB optical bandwidth falls more rapidly at higher operating temperatures that highlight the effects of leakage and backscattering processes present in the device.     

一种新的支持向量机增量学习算法

支持向量机学习算法的本质是从训练集中寻找支持向量,因此能否通过训练算法能快速找出支持向量是衡量支持向量机算法优劣的重要标准.本文提出了一种新的快速训练支持向量机的增量学习算法,首先,给出边界向量的定义,然后,对一个给定的新加人的样本,新的学习方法验证其是否为边界向量,如果是,将其加入到训练集中重新训练支持向量机,如果不是,就舍弃,这样能达到减少训练样本、降低训练复杂性目的,最后,给出了一个增量学习算法.实验表明测试误差和支持向量数量与SMO算法大致相当,而训练速度明显加快.     

Scaled and nonlinear multi-objective model for Downlink and Uplink exposure in massive MIMO

When designing wireless networks with a large number of wireless broadband devices, it is important to take into account the induced Uplink (UL) and Downlink (DL) exposure from base station broadcasting. This work focuses on the reduction of power consumption, low downlink and uplink electromagnetic exposure, and the optimization of locations and power levels of large Multiple Input–Multiple Output-Long Term Evolution base stations (MIMO-LTE). Additionally, it anticipates achieving maximum user coverage. In order to handle the power consumption and Electro Magnetic Field (EMF) exposure, a Nonlinear and Scaled Weight objective model (NLSW) is defined (DL and UL exposure). An enhanced Particle Swarm Optimization (PSO) technique is employed to resolve this optimization issue. Finally, DL exposure, UL exposure, and power performance of a NLSW are validated compared to the traditional linear model. Increased antenna leads to a 25% reduction in DL dosage. The minimum BS deployed in the area with the number of antenna elements until it reaches the ideal value is related to the UL exposure maximization.     

三点椭圆拆分算法分析

本文提出了一种对封闭空间图形椭圆的拆分方法,完成对空间中"三点确定的椭圆形"的拆分;提出拆分步长和输出步长两个不同的概念,分别确定拆分坐标点和输出坐标点,拆分方法结合变圆心角增量等步长的椭圆插补算法,通过改变拆分过程中每一个拆分周期所走过的圆心角增量来保证拆分步长的稳定,再根据输出步长,可输出不同精度要求的各点坐标。该算法运算简单、拆分稳定,可任意改变输出步长,灵活性较大,具有较好的实时性。     

A second-moment incremental formulation for the mean-field homogenization of elasto-plastic composites

In this paper, the incremental formulation for the mean-field homogenization (MFH) of elasto-plastic composites is enriched by including second statistical moments of per-phase strain increment fields, thus combining two advantages. The first one is to handle non-monotonic loading histories and the second is to better account for the heterogeneity of microscopic fields. The proposal is currently restricted to elasto-plasticity with J2 flow theory in each phase, under the small perturbation hypothesis. The formulation crucially exploits the return mapping algorithm for the J2 model, with its two steps: elastic predictor, and plastic corrections. It is shown that the second-moment measure of the average von Mises stress in each phase at the elastic predictor step plays a major role in the computation of both the average stress and the comparison tangent operator. The proposal is implemented for an extended Mori-Tanaka scheme. Predictions are compared to results provided by full-field, finite element computations of representative volume elements or unit cells, for various composite materials, with polymer or metal matrices. There are cases where the predictions of the proposed modeling improve significantly over those of a first-order incremental formulation.     

An integrated model for lot sizing with supplier selection and quantity discounts

Good inventory management is essential for a firm to be cost competitive and to acquire decent profit in the market, and how to achieve an outstanding inventory management has been a popular topic in both the academic field and in real practice for decades. As the production environment getting increasingly complex, various kinds of mathematical models have been developed, such as linear programming, nonlinear programming, mixed integer programming, geometric programming, gradient-based nonlinear programming and dynamic programming, to name a few. However, when the problem becomes NP-hard, heuristics tools may be necessary to solve the problem. In this paper, a mixed integer programming (MIP) model is constructed first to solve the lot-sizing problem with multiple suppliers, multiple periods and quantity discounts. An efficient Genetic Algorithm (GA) is proposed next to tackle the problem when it becomes too complicated. The objectives are to minimize total costs, where the costs include ordering cost, holding cost, purchase cost and transportation cost, under the requirement that no inventory shortage is allowed in the system, and to determine an appropriate inventory level for each planning period. The results demonstrate that the proposed GA model is an effective and accurate tool for determining the replenishment for a manufacturer for multi-periods.     

Output feedback guaranteed cost control of uncertain linear discrete systems with interval time-varying delays

This paper deals with output feedback guaranteed cost control problem for a general class of uncertain linear discrete delay systems, where the state and the observation output are subjected to interval time-varying delay. The proposed output feedback controller uses the observation measurement to exponentially stabilize the closed-loop system and guarantee an adequate level of system performance. By constructing a set of augmented Lyapunov–Krasovskii functionals, a delay-dependent condition for the robust output feedback guaranteed cost control is established in terms of linear matrix inequalities (LMIs). Three numerical examples are provided to demonstrate the efficiency of the proposed method.     

Semi-global finite-time output feedback stabilization for a class of large-scale uncertain nonlinear systems

This paper addresses the problem of semi-global finite-time decentralized output feedback control for large-scale systems with both higher-order and lower-order terms. A new design scheme is developed by coupling the finite-time output feedback stabilization method with the homogeneous domination approach. Specifically, we first design a homogeneous observer and an output feedback control law for each nominal subsystem without the nonlinearities. Then, based on the homogeneous domination approach, we relax the linear growth condition to a polynomial one and construct decentralized controllers to render the nonlinear system semi-globally finite-time stable.     

Incremental harmonic balance method for nonlinear flutter of an airfoil with uncertain-but-bounded parameters

The limit cycle oscillation of a two-dimensional airfoil with parameter variability in an incompressible flow is investigated using the incremental harmonic balance (IHB) method. The variable parameters, such as the wind speed, the cubic plunge and pitch stiffness coefficients, are modeled as either bounded uncertain or stochastic parameters. In the solution process of the IHB method, the bounded parameters are considered as an active increment. Taking all values over the considered bounded regions of the active parameters provides us with a series of IHB solutions of limit cycle oscillations of the airfoil. With the aid of the attained solutions, the bounds and some statistical properties of the limit cycle oscillations are determined and compared with Monte Carlo simulation (MCS) results. Numerical examples show that the proposed approach is valid and effective for analyzing strongly nonlinear vibration problems with bounded uncertainties.