Kinetics of volume expansion during infusion of Ringer’s solution based on two volume model

In this work mathematical models were developed to represent the kinetics of volume changes of fluid spaces associated with infusion of Ringer’s solution. During infusion of Ringer’s solution, the human body is assumed to be characterized by the two-fluid space model which has second volume space in addition to the first volume so that fluid exchanges between these two spaces are possible. Various infusion types were tested to accommodate different medical situations. Volunteers were given Ringer’s solution and the changes in blood hemoglobin were detected. From the comparison with experimental data, the two-fluid space model was found to represent adequately the kinetics of human volume expansion during infusion of Ringer’s solution.     

A continuous-time framework for least squares parameter estimation

This paper proposes a continuous-time framework for the least-squares parameter estimation method through evolution equations. Nonlinear systems in the standard state space representation that are linear in the unknown, constant parameters are investigated. Two estimators are studied. The first one consists of a linear evolution equation while the second one consists of an impulsive linear evolution equation. The paper discusses some theoretical aspects related to the proposed estimators: uniqueness of a solution and an attractive equilibrium point which solves for the unknown parameters. A deterministic framework for the estimation under noisy measurements is proposed using a Sobolev space with negative index to model the noise. The noise can be of large magnitude. Concrete signals issued from an electronic device are used to discuss numerical aspects.     

Source code size estimation approaches for object-oriented systems from UML class diagrams: A comparative study

BackgroundSource code size in terms of SLOC (source lines of code) is the input of many parametric software effort estimation models. However, it is unavailable at the early phase of software development.ObjectiveWe investigate the accuracy of early SLOC estimation approaches for an object-oriented system using the information collected from its UML class diagram available at the early software development phase.MethodWe use different modeling techniques to build the prediction models for investigating the accuracy of six types of metrics to estimate SLOC. The used techniques include linear models, non-linear models, rule/tree-based models, and instance-based models. The investigated metrics are class diagram metrics, predictive object points, object-oriented project size metric, fast&&serious class points, objective class points, and object-oriented function points.ResultsBased on 100 open-source Java systems, we find that the prediction model built using object-oriented project size metric and ordinary least square regression with a logarithmic transformation achieves the highest accuracy (mean MMRE = 0.19 and mean Pred(25) = 0.74).ConclusionWe should use object-oriented project size metric and ordinary least square regression with a logarithmic transformation to build a simple, accurate, and comprehensible SLOC estimation model.     

有限元方法在离心机转鼓强度分析中的应用

在回顾以往转鼓强度分析的基础上 ,指出了目前转鼓有限元应力分析所存在的问题 ,给出了提高计算精度和保证模拟有效性的注意事项 ,并探讨了转鼓强度评定准则     

X波段85W功率放大模块微带电路设计

针对X波段50 W GaN功放管电路进行改进设计,在满足原有指标的条件下,同时提高电路工作稳定性;巧妙改变微波电路结构,去除了原电路所用的电感,并在不影响电路指标的前提下适当减少了电容、电阻的用量,为整个电路的设计节约了成本。同时,仿真并制作了Wilkinson功分功合器。最终得到85 W功率放大模块,并给出了测试结果。     

Security concepts for the dynamics of autonomous vehicle networks

The secure operation of autonomous vehicle networks in the presence of adversarial observation is examined, in the context of a canonical double-integrator-network (DIN) model. Specifically, we study the ability of a sentient adversary to estimate the full network’s state, from noisy local measurements of vehicle motions. Algebraic, spectral, and graphical characterizations are provided, which indicate the critical role of the inter-vehicle communication topology and control scheme in achieving security.     

多标准视频编码器下的运动估计评估

运动估计是视频编码过程中最为复杂和耗时的阶段。为分析和优化其性能,从多个流行的开源视频编码器中提取出单独的运动估计算法模块,根据视频分辨率和视频内容的不同建立程序输入集,从而构成一套完整的测试程序集合。利用性能分析工具对算法性能和微体系结构性能进行量化分析,给出这些算法在当今主流处理器体系结构上的性能差异。实验结果表明,复杂视频和高分辨率视频下的运动估计算法耗时最长,且大部分算法的指令级并行性没有太大差异。算法最后一级高速缓存的缺失率和分支误预测率都较低,分别在0.01%和7%以下。     

Computer Algebra Derivation of the Bias of Linear Estimators of Autoregressive Models

Abstract. A symbolic method which can be used to obtain the asymptotic bias and variance coefficients to order O(1/n) for estimators in stationary time series is discussed. Using this method, the large‐sample bias of the Burg estimator in the AR(p) for p = 1, 2, 3 is shown to be equal to that of the least squares estimators in both the known and unknown mean cases. Previous researchers have only been able to obtain simulation results for the Burg estimator's bias because this problem is too intractable without using computer algebra. The asymptotic bias coefficient to O(1/n) of Yule–Walker as well as least squares estimates is also derived in AR(3) models. Our asymptotic results show that for the AR(3), just as in the AR(2), the Yule–Walker estimates have a large bias when the parameters are near the nonstationary boundary. The least squares and Burg estimates are much better in this situation. Simulation results confirm our findings.     

基于集成温度传感器的硅微陀螺仪数字化温度补偿研究

提出了一种基于集成温度传感器的硅微陀螺仪数字化温度补偿方法。首先,介绍了集成温度传感器的硅微陀螺仪基本结构原理,分析了硅微陀螺仪动力学方程以及温度变化对硅微陀螺仪谐振频率、品质因数、标度因数和零偏的影响。然后,设计了基于FPGA的硅微陀螺仪数字化补偿电路。最后,经过温度特性实验得到标度因数和零偏随温度变化曲线,建立了温度补偿模型,提出分段温度补偿方法。经过温度补偿后,标度因数和零偏的温度系数分别由316.66×10-6/℃和366.22°/(h·℃)减小为69.67×10-6/℃和115.25°/(h·℃),证明了补偿方法的正确性和可行性。     

突发GMSK混和信号混合位置估计迭代算法

针对GMSK混合信号的混合位置估计问题,提出了一种基于参数估计与混合位置估计的迭代算法。混合信号混合部位和未混合部位在幅度和频率上存在明显差异,通过混合部位信号过零点和极值点得到混合的信号和幅度估计后,可以对采样点是否混合进行判断,同时混合起点对应着相对时延,当混合信号的相对时延较大时,利用未混合部位信号来进行迭代时,其估计精度更高。对混合起点估计的克拉美罗界进行了推导,仿真表明,本文算法估计精度高,所需的数据量小,适用于突发通信,且对参数变化不敏感,具有较强的鲁棒性,在高信噪比下混合位置估计精度接近克拉美罗界。