超声多模态评分及sFlt-1、D-Dimer对原因不明复发性流产妊娠结局的预测

目的探讨超声多模态评分及可溶性血管内皮生长因子受体-1(Soluble vascular endothelial growth factor receptor-1,sFlt-1)、D-二聚体(D-dimer,D-D)对原因不明复发性流产(Unexplained recurrent spontaneous abortion,URSA)妊娠结局的预测价值,并构建URSA不良妊娠结局的风险预测模型。方法选取2020年4月至2022年3月东莞市妇幼保健院收治的有URSA史的早孕患者136例,根据随访妊娠结局分为流产组和未流产组,比较两组超声多模态评分及sFlt-1、D-D水平,采用多因素Logistic回归分析法分析影响URSA妊娠再次流产的危险因素,建立风险预测模型并进行模型验证。结果136例孕妇保胎治疗后流产率为38.24%。流产组年龄≥35岁、饮酒史、URSA家族史、自然流产≥4次患者占比及血清sFlt-1、D-D水平均高于未流产组,孕酮及超声多模态评分均低于未流产组(P<0.05)。二元Logistic回归分析显示,自然流产≥4次、sFlt-1高水平、D-D高水平、超声多模态评分低是影响URSA妊娠再流产的独立危险因素(P<0.05)。预测模型方程:Logit(P)=-1.635+0.605×自然流产≥4次+1.332×sFlt-1+0.841×D-D+1.042×超声多模态评分;内部验证结果显示,预测模型的校正曲线与理想曲线拟合良好(Hosmer-Lemeshowχ^(2)=0.322,P=0.113)。受试者工作特征(Receiver operating characteristic,ROC)曲线结果显示,Logistic预测模型的AUC为0.933(95%CI:0.877~0.969),优于sFlt-1、D-D、超声多模态评分单项预测(P<0.05)。结论血清sFlt-1、D-D水平升高、超声多模态评分降低、自然流产≥4次是URSA妊娠再流产的高危因素,构建的风险预测模型区分度、拟合度好,能够直观准确预测URSA不良妊娠结局发生风险。

Performance Optimization of Torque Converters Based on Modified 1D Flow Model

A methodology for performance optimization of torque converters is put forward based on the one-dimensional (1D) flow model. It is found that the inaccuracy of 1D flow model for predicting hydraulic performance at the low speed ratio is mainly caused by the separation phenomenon at the stator cascade which is induced by large flow impinging at the pressure side of the stator blades. A semi-empirical separation model is presented and incorporated to the original 1D flow model. It is illustrated that the improved model is able to predict the circumferential velocity components accurately, which can be applied to performance optimization. Then, the Pareto front is obtained by using the genetic algorithm (GA) in order to inspect the coupled relationship among stalling impeller torque capacity, stalling torque ratio and efficiency. The efficiency is maximized on the premise that a target stalling impeller torque capacity and torque ratio are achieved. Finally, the optimized result is verified by the computational fluid dynamics(CFD) simulation, which indicates that the maximal efficiency is increased by 0.96%.

Experiments on Exploration of Shallow Fine Structures and the Construction of the 1-D Velocity Model in the Pingtan Island,Fujian

112 short-period seismographs were set up in the 400 km^2 area of Pingtan Island and its surrounding areas in Fujian.The combined observations of the airgun source and ambient noise source were carried out using a dense array to receive the 387 airgun signals excited around the island and one month of continuous ambient noise recording.The 1-D P-wave and S-wave shallow velocity model of Pingtan Island is obtained by the inversion of the airgun body wave’s first arrival time data,and the reliability of the velocity model is verified by using the surface wave phase velocity dispersion curve,which can provide initial model for subsequent 3-D imaging.The experimental results show that this experiment is a successful demonstration of local scale green non-destructive detection,which can provide basic data for shallow surface structure research and strong vibration simulation of the Pingtan Island.

Analysis of piezoelectric semiconductor fibers under gradient temperature changes

Piezoelectric semiconductors(PSs)possess both semiconducting properties and piezoelectric coupling effects,making them optimal building blocks for semiconductor devices.PS fiber-like structures have wide applications in multi-functional semiconductor devices.In this paper,a one-dimensional(1D)theoretical model is established to describe the piezotronic responses of a PS fiber under gradient temperature changes.The theoretical model aims to explain the mechanism behind the resistance change caused by such gradient temperature changes.Numerical results demonstrate that a gradient temperature change significantly affects the physical fields within the PS fiber,and can induce changes in its surface resistance.It provides important theoretical guidance on the development of piezotronic devices that are sensitive to temperature effects.

Validation of 1D model for methane/air/Pt combustion in stagnation flow

A 2D model is built on the package of FLUENT to study the effects of radial aspect ratio （R/W）, length-to-width ratio （L/W）, strain rate （SR）, and buoyancy （Ri=Gr/Re^2） on the validation of the simplified 1D model. In the present 2D model, the methane/air homogeneous reaction mechanism of Peters and the methane/air/platinum heterogeneous reaction mechanism of Deutschmann are applied. By comparison between the 1D and 2D numerical results, it is found that the validation of 1D model is highly related with the catalytic stagnation reactor configuration. For length-to-width ratio L/W = 1 configuration, 1D laminar model is applicable when the radial aspect ratio R/W 〉 0.4. For R/W = 0.6, the reactor exhibited 1D characteristics when L/W 〈 1. Compared with the temperature and species profiles, the velocity distribution along the axis is more sensitive to the change of radial aspect ratio and length-to-width ratio. With increasing of the strain rate, the flame front goes closer to the catalytic wall surface and the difference between the 1D and 2D results decreases. For a valid 1D simulation, it is recommended that the strain rate should be convection can be neglected when Ri〈 5. greater than 20 s^-1. The effects of natural

An Implicit Coupled 1D/2D Model for Unsteady Subcritical Flow in Channel Networks and Embayment

In this study, 1D and 2D shallow-water models were coupled to simulate unsteady flow in channel networks and embayment. The 1D model solved the 1D shallow-water equations (St. Venant) using the Preissmann box method and targeted long narrow reaches of the river networks, while the 2D model targeted broad channels and embayment and solved the 2D shallow-water equations using a semi-implicit scheme applied to an unstructured grid of triangular cells. The 1D and 2D models were solved simultaneously by building a matrix for the free surface elevation at every 1D junction and 2D cell center. Velocities were then computed explicitly based on the results at the previous time step and the updated water level. The originality of the scheme arose from a novel coupling method. The results showed that the coupled 1D/2D model produced identical results as the full 2D model in classical to benchmark problems with considerable savings in computational effort. Application of the model to the Pearl River Estuary in southern China showed that complex patterns of tidal wave propagation could be efficiently modeled.

Simulation of the Hydrodynamic Functioning of the Cavally River Using a Coupled 1D-2D Model in the Ity Area (Zouan-Hounien in Côte d’Ivoire)

In recent years, the Cavally River has been subject to multiple activities, including the construction of diversion channels and a bridge that makes it vulnerable to flooding. In order to assess the impact of these hydraulic structures on the river hydrodynamic functioning, a 1D-2D model was realized. The implementation of the 1D-2D model consisted of first running the 1D model, then the 2D model, and finally in coupling them. The 1D-2D model was designed with the 1988 flood hydrograph, a Manning’s coefficient of 0.052 m1/3/s for the minor bed and 0.06 m1/3/s for the major bed. The results of the hydraulic model show that the velocities are almost identical to those of the Cavally in natural operation. The values of the velocities are included between 0.4 m/s and 1.3 m/s at the level of the minor bed of the river and between 0.06 m/s and 0.71 m/s at the level of the floodplains. The average water level for flood propagation is 262.37 ± 0.44 m before construction of the structures and 262.23 ± 0.85 m after construction of the structures. The 0.41 m reduction in water level due to the diversion canal and bridge is negligible compared to the total fluctuations of the Cavally River, which vary from 6 to 7 m over the year.

A Turbine Blade Parametric Modeling Method Considering 1-D Heat Transfer Analysis

Traditional feature-based turbine blade models can match the needs of geometric modeling but could hardly meet the requirement of data extraction in 1-D heat transfer analysis. In this paper, the requirements of data extraction in 1-D heat transfer analysis are taken into consideration as well as geometric representation in parametric design process. An improved turbine blade parametric modeling method is proposed. Based on the modeling method proposed, a system structure of blade modeling process considering 1-D heat transfer analysis is devised. Eventually, a turbine blade parametric modeling system is constructed to test and verify the feasibility of the proposed modeling method and system structure. Experiments show that the blade parametric modeling method proposed can make geometric models better adapt to the specific requirements of 1-D heat transfer analysis and has certain reference value to the creation of high quality digital models.

多变量灰色模型MGM(1,n)在R&D投资预测中的应用

对未来R&D经费总量及其与GDP比值进行科学的预测是制定科技发展规划的重要组成部分.提出一种定量分析预测方法———利用多变量灰色MGM(1,n)模型(mu lti-variab le grey model),研究R&D投入与GDP所形成的复杂系统变量之间的相互影响关系,对天津市相关数据资料进行实证分析与中长期预测,为政府相关部门制订科学的科技发展规划提供有益的指导作用.

基于离散余弦变换的GM(1,1,d)预测模型

针对实测数据的噪声导致预测模型的预测精度下降问题,利用离散余弦变换对实数具有较强降噪功能的优势,结合灰色系统理论建模机理,构建基于离散余弦变换的GM(1,1,d)模型,并给出了相应的算法和步骤.该模型通过离散余弦变换对数据进行去伪存真的清洗,有效降低了随机扰动误差,提高了预测精度.算例表明,GM(1,1,d)模型能显著提高模型的预测精度.

基于MGM(1,n)的R&D投入预测分析

当观测资料的数据量少而又存在多个相互影响或关联的变量时,常用的灰色GM(1,1)模型不能全面考虑多个变量,GM(1,n)模型也不能考虑相互影响问题,而采用MGM(1,n)模型,较好地解决了这一问题。MGM(1,n)模型是GM(1,1)模型在n元多变量情况下的推广,其参数能够反映实际工程或社会系统中多个变量间的相互影响、相互制约的关系。内容包括:建模变量的选择,建立n元微分方程组,求解变量的时间响应函数和模型检验,并对GDP和R&D进行了预测。

2013年辽宁灯塔M5.1地震前小震序列震源机制一致性特征

从辽宁测震台网2012年1月1日至2022年7月10日的观测报告中筛选出36049条Pg震相走时数据,反演了辽宁地区最小一维P波速度模型。采用P波初动方法求解了2012年1月1日至2013年1月23日灯塔M 5.1地震发生前,震中附近M_(L)2.5~4.1地震震源机制解,并根据三角形图解分类方法进行了分类。计算了这些小震与灯塔M 5.1地震震源机制解的最小空间旋转角,通过分析其变化趋势,发现灯塔M 5.1地震前小震序列存在明显的震源机制一致性特征。

One-dimensional breakdown voltage model of SOI RESURF lateral power device based on lateral linearly graded approximation

A novel one-dimensional（1D） analytical model is proposed for quantifying the breakdown voltage of a reduced surface field（RESURF） lateral power device fabricated on silicon on an insulator（SOI） substrate.We assume that the charges in the depletion region contribute to the lateral PN junctions along the diagonal of the area shared by the lateral and vertical depletion regions.Based on the assumption,the lateral PN junction behaves as a linearly graded junction,thus resulting in a reduced surface electric field and high breakdown voltage.Using the proposed model,the breakdown voltage as a function of device parameters is investigated and compared with the numerical simulation by the TCAD tools.The analytical results are shown to be in fair agreement with the numerical results.Finally,a new RESURF criterion is derived which offers a useful scheme to optimize the structure parameters.This simple 1D model provides a clear physical insight into the RESURF effect and a new explanation on the improvement in breakdown voltage in an SOI RESURF device.

Applying Deep Learning Models to Mouse Behavior Recognition

In many animal-related studies, a high-performance animal behavior recognition system can help researchers reduce or get rid of the limitation of human assessments and make the experiments easier to reproduce. Recently, although deep learning models are holding state-of-the-art performances in human action recognition tasks, these models are not well-studied in applying to animal behavior recognition tasks. One reason is the lack of extensive datasets which are required to train these deep models for good performances. In this research, we investigated two current state-of-the-art deep learning models in human action recognition tasks, the I3D model and the R(2 + 1)D model, in solving a mouse behavior recognition task. We compared their performances with other models from previous researches and the results showed that the deep learning models that pre-trained using human action datasets then fine-tuned using the mouse behavior dataset can outperform other models from previous researches. It also shows promises of applying these deep learning models to other animal behavior recognition tasks without any significant modification in the models’ architecture, all we need to do is collecting proper datasets for the tasks and fine-tuning the pre-trained models using the collected data.

Mathematical model for flood routing in Jingjiang River and Dongting Lake network

The main stream of the Yangtze River, Dongting Lake, and the river network in the Jingjiang reach of the Yangtze River constitute a complex water system. This paper develops a one-dimensional （l-D） mathematical model for flood routing in the river network Of the Jingjiang River and Dongting Lake using the explicit finite volume method. Based on observed data during the flood periods in 1996 and 1998, the model was calibrated and validated, and the results show that the model is effective and has high accuracy. In addition, the one-dimensional mathematical model for the river network and the horizontal two-dimensional （2-D） mathematical model for the Jingjiang flood diversion area were coupled to simulate the flood process in the Jingjiang River, Dongting Lake, and the Jingjiang flood diversion area. The calculated results of the coupled model are consistent with the practical processes. Meanwhile, the results show that the flood diversion has significant effects on the decrease of the peak water level at the Shashi and Chenjiawan hydrological stations near the flood diversion gates, and the effect is more obvious in the downstream than in the upstream.

空竭服务与服务员可选休假的M/D/1排队模型研究

运用Hille-Yosida定理,Phillips定理与Fattorini定理,证明了空竭服务与服务员可选休假的M/D/1排队模型存在唯一的概率瞬态解.在一定的条件下,通过研究该模型的主算子的谱特征得到该模型的时间依赖解强收敛于该模型的稳态解.

Controlling of NO_x Emitted from a Diesel Engine Fueled on Biodiesel: Theoretical Modeling and Experimental Evaluation

The development of a diesel engine model using one-dimensional （1-D） fluid-dynamic engine simulation codes,and its validation using experimental measurements are described in this paper.The model was calibrated by running the engine on an electric dynamometer at eight steady-state operating conditions.The refined engine model was used to predict the oxides of nitrogen （NOx） less than those measured earlier in the experiments,and hence to recommend changes in the engine for the verification of the results.The refined engine model is greatly influenced by the start of injection angle （ψ）,ignition delay （φ）,premix duration （DP）,and main duration （DM） for the prediction of reduced NOx emissions.It is found that optimum ψ is 6.5° before top dead center （BTDC）.At this angle,the predicted and experimental results are in good agreement,showing only a difference of up to 4%,6.2%,and 7.5% for engine performance,maximum combustion pressure （Pmax）,and NOx,respectively.

HEC-RAS和MIKE11模型河床糙率应用比较研究

近十几年来,科学技术的发展为水流运动的数学模型研究提供了有利条件,并出现了大批商用软件。HEC-RAS和MIKE11作为最常用的一维水流模型商用计算软件,被广泛用于计算不同水文条件、工程前后河段的水流运动,并均有较好的计算结果。然而,两种软件从模型假设、建立到运行等方面存在着许多差异。本文着重以HEC-RAS和MIKE11对河道糙率的不同计算方法为出发点,利用赣江外洲至南昌段实测地形和水文资料进行计算,然后对计算结果进行比较分析,得到两种软件的联系与区别。

活性污泥系统生物场-水力场-温度场耦合模型(FCASM3-Hydro-Temp)Ⅰ:模型建立

由活性污泥系统内生物场、水力场和温度场之间相互影响关系分析以及活性污泥系统多场耦合模型研究现状可知,当前亟需建立既能准确反映活性污泥系统污染物质去除过程,同时又充分考虑水力及温度作用的多场耦合模型.基于活性污泥系统内生物场、水力场和温度场之间相互影响关系的研究,以全耦合活性污泥模型(FCASM3)为新平台,采用一维对流-弥散方程的形式建立了活性污泥系统生物场-水力场-温度场耦合模型(FCASM3-Hydro-Temp),该模型充分考虑了生物场、水力场和温度场三者之间的相互作用.

风洞整流孔板流动CFD边界条件建模

风洞设计中,普遍采用孔板、金属网等构件进行整流。但孔板流动很复杂,一般只能依据经验并开展引导性试验进行设计与优化。随着CFD技术的发展,风洞设计自然也希望能利用CFD技术,但孔板等复杂构件的流动对此造成很大挑战。通过忽略孔板大量微小开孔中的流动细节,仅考虑多孔板的宏观效应,建立了一种反映多孔板宏观效应的CFD计算边界条件模型,极大缩减了计算规模,并结合2m×2m超声速风洞引导性试验进行了初步计算应用,取得了一定的效果。