Subdivision based isogeometric analysis for geometric flows

We present a new isogeometric analysis (IGA) approach based on extended Loop subdivision scheme for solving various geometric flows defined on subdivision surfaces. The studied flows include the second-order, fourth-order, and sixth-order geometric flows, such as averaged mean curvature flow, constant mean curvature flow, and minimal mean-curvature-variation flow, which are generally derived by minimizing the associate energy functionals with $L^2$-gradient flow respectively. The geometric flows are discretized by means of subdivision based IGA, where the finite element space is formulated by the limit form of the extended Loop subdivision for different initial control meshes. The basis functions, consisting of quartic box-splines corresponding to each subdivided control mesh, are utilized to represent the geometry exactly. For the cases of the evolution of open surfaces with any shape boundary, high-order continuous boundary conditions derived from the mixed variational forms of the geometric flows should be implemented to be consistent with the isogeometric concept. For time discretization, we adopt an adaptive semi-implicit Euler scheme. By several numerical experiments, we study the convergence behaviors of the proposed approach for solving the geometric flows with high-order boundary conditions. Moreover, the numerical results also show the accuracy and efficiency of the proposed method.     

采煤机惯性导航定位动态零速修正技术

基于捷联惯性导航与轴编码器组合的采煤机惯性导航定位是综采工作面可行的采煤机定位技术。惯性导航提供姿态角参数，轴编码器提供速度参数，采煤机惯性导航定位利用航位推算算法解算出东北天坐标系下的位置坐标。为了进一步提高定位精度，在消除确定性偏差的基础上，根据惯性导航姿态误差方程，以东、北、天3个方向的平台失准角为状态量构建状态方程，根据动态零速修正技术的非完整约束条件，以采煤机坐标系横向和垂直方向速度值为观测量构建量测方程，建立卡尔曼滤波模型，并进行移动平台模拟采煤机运行试验验证。在试验条件下，第3刀导航东、北方向最大误差分别由0.639 7，0.856 7 m减小为0.456 4，0.594 2 m。第4刀导航东、北方向最大误差分别由0.644 4，0.910 6 m减小为0.466 5，0.603 0 m。东、北方向定位精度提升了30%。     

基于双层修正无迹卡尔曼的水下节点定位算法* .txt

摘要：针对水下无线传感网络中运动节点定位精度低的问题，提出了一种新的基于双层修正无迹卡尔曼的水下节点定位算法(DLMUKF)。该算法利用下层无迹卡尔曼滤波算法对节点状态进行预测，根据各信标节点的测距传播时延对预测的节点状态进行修正。运用上层无迹卡尔曼滤波算法对修正后的状态进行新的预测与修正。仿真实验中，DLMUKF算法的平均定位误差约为传统多边定位算法的15%，约为基于无迹卡尔曼滤波（UKF）定位算法的16%，受节点运动时间与速度的影响最小。通过实验证明DLMUKF算法能更充分利用实际距离值，可以有效减小运动节点的定位误差。 .txt     

Early-lactation extended pirlimycin therapy against naturally acquired Staphylococcus aureus intramammary infections in heifers: A randomized controlled trial

The primary objective of the current study was to evaluate cure rate following an early-lactation extended intramammary pirlimycin treatment on heifers naturally infected by Staphylococcus aureus. The secondary objective was to assess Petrifilm Staph Express (3M Microbiology, St. Paul, MN) count plate characteristics when used in a protocol for early-lactation detection of infected quarters in heifers. Milk samples were collected from heifers (n = 946) in the first few days following calving (mean = 5 d). Heifers with laboratory-confirmed S. aureus intramammary infection (n = 72) were randomly allocated into 2 groups. The treatment group (n = 54 quarters from 38 heifers) received an intramammary infusion of 50 mg of pirlimycin once per day for 8 consecutive days in infected quarters. The control group (n = 44 quarters from 34 heifers) did not receive any treatment. Treatment success was defined as having negative culture results for S. aureus in all 3 post-treatment quarter milk samples collected on d 17, 24, and 31 post-treatment. Treatment group mammary quarters showed a statistically significant higher cure rate (64.8%) compared with the control group (34.1%). A total of 38% of quarters identified as S. aureus-positive using the Petrifilm Staph Express count plate were in fact identified as non-aureus staphylococci on routine laboratory-based bacteriological culture. The current study demonstrates that a higher cure rate for S. aureus IMI can be achieved in dairy heifers if an extended treatment protocol is put in place soon after calving. Use of Petrifilm Staph Express count plate for identification of S. aureus-infected heifers could lead to unnecessary treatments because of false-positive results.     

New version of continuous–discrete cubature Kalman filtering for nonlinear continuous–discrete systems

For nonlinear continuous–discrete systems, this paper elaborates a new accurate implementation of continuous–discrete cubature Kalman filter (CD-CKF). As the main contribution of this work, the new Kalman prediction stage begins by integrating the nonlinear continuous model for all the cubature sample vectors; the prior estimate state and covariance prediction are based on the weighted statistics of these integrated cubature sample vectors and the Gauss–Legendre approximation scheme. The new square root form CD-CKF is also derived and accurately implemented by combining with the modified variable stepsize NIRK. As the advantages of proposed approach, the complicated and error-prone processes of solving covariance differential equation or calculating derivatives are avoided, while the positive semi-definiteness of prior error covariance are numerically guaranteed. Simulations of traffic control scenarios further confirm the new approach’s superior filtering performance in both reliability and accuracy.     

Propagation of surface cracks on beam blank in the mould during continuous casting

ABSTRACT

We focus on crack propagation to investigate surface cracks in the mould during continuous casting, based on the crack initiation mechanism proposed in previous studies. The temperature and stress data of a solidified shell were extracted, and an extended finite element model based on the continuous damage theory of elastic–plastic materials was developed to simulate surface crack propagation. The results showed that, in the cracked area, stress concentration occurred at the crack tip, and the element split open and the crack propagated when the maximum principal stress in the stress concentration area reached the critical value. Prefabricated cracks in the fillet and web mainly developed into longitudinal cracks in the mould. The theoretical mechanism of this study was found to be the same as the crack propagation mechanism observed during the actual production of beam blanks. Thus, this study reveals the theoretical principle of crack initiation and propagation and can provide theoretical guidance for controlling surface cracks during beam blank continuous casting.     

Individual-based multi-objective optimal structured treatment interruption for HIV infection

In this paper, based on the measurable quantities from an individual patient that has infection to human immunodeficiency virus (HIV) and his/her condition is near to acquired immune deficiency syndrome (AIDS), individual-based multi-objective optimal treatments have been proposed. Firstly, the most effective parameters of the patient in computing Long-term non-progressor (LTNP) equilibrium are derived using global sensitivity analysis (GSA). To accomplish GSA effectively, Latin hypercube sampling (LHS) and partial rank correlation coefficients (PRCC) are utilized to rank each of the parameters based on each state of the 5-dimensional model. Then, these results are used by Dempster–Shafer (D–S) evidence theory (DSET) to rank the most effective parameters comprehensively. Now, these effective identified parameters are estimated using extended Kalman filter (EKF), which its covariance matrices are optimized based on particle swarm optimization (PSO) algorithm. Thus, the proposed methodology gives a calibrated model corresponding to the individual patient. Based on this calibrated model, the LTNP equilibrium related to the individual patient is derived. Using the derived individual-based LTNP equilibrium optimal structured treatment interruption (STI) strategies are extracted by defining suitable multi-objective optimization problem and solving it through using non-dominated sorting genetic algorithm-II (NSGA-II). The results demonstrate that the proposed optimal treatments are able to effectively reach LTNP equilibrium with using the minimum and maximum drug usage of 3.6% and 35.1% of full drug usage treatment. Meanwhile, the different optimal treatments give the decision-makers enough flexibility to choose the suitable treatment based on existing facilities and necessities.     

An innovative technology of directional propagation of hydraulic fracture guided by radial holes in fossil hydrogen energy development

Conventional hydraulic fracturing fails to develop low permeability reservoirs of fossil hydrogen energy that are not located in the direction of maximum principal in-situ stress. A new technology of fracture propagation guided by radial holes is proposed, which can realize directional propagation of hydraulic fracture along radial holes in fossil hydrogen energy development. In order to verify this new technology, a model of radial holes combined with hydraulic fracturing is established by the ABAQUS extended finite element method. Simulation results show that radial holes play a guiding role in fractures propagation. The influence extent of seven factors on the directional propagation of hydraulic fracture is listed as follows (from strong to weak): azimuth of radial holes > horizontal in-situ stress difference of fossil hydrogen reservoir > injection rate of fracturing fluid > Young's modulus of rock > permeability of fossil hydrogen reservoir > Poisson ratio of rock > viscosity of fracturing fluid. True tri-axial experiment is carried out to verify the accuracy of numerical simulation, and the result is consistent with numerical model, which indicates that numerical simulation is reliable.     

Sensors incipient fault detection and isolation of nuclear power plant using extended Kalman filter and Kullback–Leibler divergence

Sensor real-time monitoring is an indispensable to achieve reliable plant operation along with stricter safety and environmental measures. This paper presents a statistical algorithm for sensors time-varying incipient fault detection and isolation. The proposed approach formulates the fault detection index and fault signature using the extended Kalman filter. Algorithm relaxes assumption on a monitored system stability and a priori knowledge of the fault profile. Further, fault decision statistics has been devised using Kullback–Leibler Divergence (KLD) and mixed with an Exponential Weighted Moving Average (EWMA) control chart. Pressurized water reactor nuclear power plant temperature and neutron flux sensors incipient fault detection and isolation have been demonstrated to illustrate the effectiveness of proposed methodology.