Beyond boundaries:Feasibility of curved linear array echoendoscope in appendiceal neoplasm detection

We recently read with great interest a study by Zhang et al in the World Journal of Gastroenterology.In our practice,we focus specifically on examining appendiceal mucinous neoplasms(AMNs)with endoscopic ultrasound(EUS)using different scopes.AMNs are rare neoplastic lesions characterized by an accumulation of mucin inside a cystic dilatation of the appendix.Clinically,they can present as nonspecific acute appendicitis.AMNs can turn into a life-threatening condition,termed pseudomyxoma peritonei,in which the ruptured appendix causes accumulation of mucin in the abdomen.Therefore,accurate and rapid diagnosis of AMN is essential.EUS is able to confirm and stage AMNs;although,EUS examination was once limited to the rectal and anal regions due to the conven-tional oblique-view scopes.With the emergence of new forward-view linear echoendoscopes and instruments like EUS miniprobes and overtubes,the scope of examination is changing.Herein,we discuss the feasibility of using the curved linear array echoendoscopes to examine cecal and appendiceal orifice lesions.

The Effectiveness of the Havriliak-Negami Model in Predicting the Master Curves of the Asphalt Blends with SBS Triblock Copolymer and Organic-Montmorillonite at Different Temperatures and Frequencies

The dynamic viscoelastic properties of asphalt AC-20 and its composites with Organic-Montmorillonite clay (OMMt) and SBS were modeled using the empirical Havriliak-Negami (HN) model, based on linear viscoelastic theory (LVE). The HN parameters, α, β, G0, G∞and τHN were determined by solving the HN equation across various temperatures and frequencies. The HN model successfully predicted the rheological behavior of the asphalt and its blends within the temperature range of 25˚C - 40˚C. However, deviations occurred between 40˚C - 75˚C, where the glass transition temperature Tg of the asphalt components and the SBS polymer are located, rendering the HN model ineffective for predicting the dynamic viscoelastic properties of composites containing OMMt under these conditions. Yet, the prediction error of the HN model dropped to 2.28% - 2.81% for asphalt and its mixtures at 100˚C, a temperature exceeding the Tg values of both polymer and asphalt, where the mixtures exhibited a liquid-like behavior. The exponent α and the relaxation time increased with temperature across all systems. Incorporating OMMt clay into the asphalt blends significantly enhanced the relaxation dynamics of the resulting composites.

ADMISSIBILITY OF LINEAR ESTIMATORS IN A GROWTH CURVE MODEL SUBJECT TO AN INCOMPLETE ELLIPSOIDAL RESTRICTION

This article considers the admissibility of the linear estimators for the regression coefficients in the growth curve model subject to an incomplete ellipsoidal restriction. The necessary and sufficient conditions for linear estimators to be admissible in classes of the homogeneous and non-homogeneous linear estimators, respectively, are obtained under the quadratic loss function. They are generalizations of some existing results in literature.

Computer program of nonlinear, curved regression for ‘probacent’-probability equation in biomedicine

On the basis of experimental observations on animals, applications to clinical data on patients and theoretical statistical reasoning, the author developed a com-puter-assisted general mathematical model of the ‘probacent’-probability equation, Equation (1) and death rate (mortality probability) equation, Equation (2) derivable from Equation (1) that may be applica-ble as a general approximation method to make use-ful predictions of probable outcomes in a variety of biomedical phenomena [1-4]. Equations (1) and (2) contain a constant, γ and c, respectively. In the pre-vious studies, the author used the least maximum- difference principle to determine these constants that were expected to best fit reported data, minimizing the deviation. In this study, the author uses the method of computer-assisted least sum of squares to determine the constants, γ and c in constructing the ‘probacent’-related formulas best fitting the NCHS- reported data on survival probabilities and death rates in the US total adult population for 2001. The results of this study reveal that the method of com-puter-assisted mathematical analysis with the least sum of squares seems to be simple, more accurate, convenient and preferable than the previously used least maximum-difference principle, and better fit-ting the NCHS-reported data on survival probabili-ties and death rates in the US total adult population. The computer program of curved regression for the ‘probacent’-probability and death rate equations may be helpful in research in biomedicine.

GENERAL ADMISSIBLE LINEARESTIMATORS IN RESTRICEDGROWTH CURVE MODEL

In this paper, we give a class of fuation and use to dicuss general admissibility according to general optimality ceriteria defined uader restricted growth curve model. General admissible characterization are obtained. Moreover, these conditions are then utilize to characterize infulueace that restrictions involved in growth curve model have on the class of admissible linear

Application of curved ablation in liver cancer with special morphology or location: Report of two cases

BACKGROUND Liver cancer is one of the most common malignant tumors with a high incidence and mortality.Hepatitis-liver cirrhosis-liver cancer is known as the trilogy of liver cancer.At present,due to significant development of imaging interventions,they occupy an irreplaceable position in the field of liver cancer treatment,especially ultrasound-guided ablation.Because patients with liver cancer often present with liver cirrhosis,which leads to morphological deformation of the liver,it is difficult to perform a linear ablation of liver cancer in the areas near the phrenic top and within large blood vessels,among others.The present study reports on two cases of liver cancer that have been subjected to curvilinear ablation.After 1 mo,magnetic resonance imaging showed complete ablation,demonstrating that ultrasound-guided curved ablation is feasible and effective in the treatment of liver cancer.CASE SUMMARY Two patients were treated at the Liver Disease Department of the Xixi Hospital Affiliated to Zhejiang University of Chinese Medicine in 2019.Because the first liver cancer patient’s tumor was located close to the diaphragm,it was difficult to complete a straight needle ablation procedure in one session.In order to achieve accurate and minimally invasive treatment of this tumor,a curved needle ablation procedure was designed.The second patient presented with a hepatic cyst in front of the tumor.In order not to damage the hepatic cyst,a looper needle ablation technique was used.The procedure was successfully completed in both cases.CONCLUSION Curved ablation is a new technique that can be used to treat tumors situated in a variety of locations,providing new ideas for interventional techniques.Its operation difficulty is higher and further animal experiments are necessary to improve the operation procedure.

Efficient Construction of B-Spline Curves with Minimal Internal Energy

In this paper,we propose an efficient method to construct energy-minimizing B-spline curves by using discrete mask method.The linear relations between control points are firstly derived for different energy-minimization problems,then the construction of B-spline curve with minimal internal energy can be addressed by solving a sparse linear system.The existence and uniqueness of the solution for the linear system are also proved.Experimental results show the efficiency of the proposed approach,and its application in 1 G blending curve construction is also presented.

ADMISSIBILITY IN THE GENERAL GROWTH CURVE MODEL WITH RESPECT TO RESTRICTED PARAMETER SETS UNDER MATRIX LOSS FUNCTION

In this paper, we study the issue of admissibility in the growth curve model with respect to restricted parameter sets under matrix loss function. We obtain some neces- sary and sufficient conditions that the linear estimators of KBL are admissible in the class of homogeneous linear estimators and in the class of non-homogeneous linear estimators under the growth curve model with respect to restricted parameter sets, respectively.

Some Key Technologies of a New-type CNC Curve Grinding Machine

This paper presented a new-type CNC curve grinding machine, in order to conquer the disadvantages of conventional NC curve grinding machine and improve surface quality, dimensional accuracy and machining efficiency. The new-type grinder adopts some high and new technologies: ① the normal tracing device could make grinding wheel coincide with the normal direction of the machining points in work piece, and improve surface quality and dimensional accuracy; ② the digital image on-line recognition system could monitor machining process and compensate wheel wear in real time; ③ linear motor drive mechanism could realize the exact adjustment of the grinding head digitally and increase the machining efficiency. The math models of normal tracing and circular tolerance zone were presented. The experimental results show that the new-type CNC curve grinding machine equipped with the three devices mentioned above is easy to realize the precision grinding of any complex curve, and improve surface quality, dimensional accuracy and machining efficiency.

High Order Tensor Forms of Growth Curve Models

In this paper, we first study the linear regression model and obtain a norm-minimized estimator of the parameter vector by using the g-inverse and the singular value decomposition of matrix X. We then investigate the growth curve model (GCM) and extend the GCM to a generalized GCM (GGCM) by using high order tensors. The parameter estimations in GGCMs are also achieved in this way.

A fault recognition method based on clustering linear regression

Aiming at the problems of low accuracy,long time consumption,and failure to obtain quantita-tive fault identification results of existing automatic fault identification technic,a fault recognition method based on clustering linear regression is proposed.Firstly,Hough transform is used to detect the line segment of the enhanced image obtained by the coherence cube algorithm.Secondly,the endpoint of the line segment detected by Hough transform is taken as the key point,and the adaptive clustering linear regression algorithm is used to cluster the key points adaptively according to the lin-ear relationship between them.Finally,a fault is generated from each category of key points based on least squares curve fitting method to realize fault identification.To verify the feasibility and pro-gressiveness of the proposed method,it is compared with the traditional method and the latest meth-od on the actual seismic data through experiments,and the effectiveness of the proposed method is verified by the experimental results on the actual seismic data.

考虑加载历史的小半径曲线桥梁梁轨相互作用分析

目前,大部分考虑加载历史的梁轨相互作用研究都集中在直线桥梁上,针对曲线桥梁,尤其是小半径曲线桥梁,梁轨相互作用的研究相对较少。采用理想弹塑性滞回阻力模型模拟扣件纵向阻力,运用有限元软件,建立以城东特大桥为研究对象的钢轨-桥梁-墩台三维有限元空间力学计算模型,研究曲线半径对于梁轨相互作用的影响,探究了多荷载耦合作用、往复荷载作用以及循环荷载作用下考虑加载历史效应的曲线桥梁梁轨相互作用情况,并提出“拉力百分比”以及“压力百分比”的概念以便分析曲线半径对传统线性叠加法误差的影响。结果表明,曲线桥梁中梁轨纵、横向相互作用分别与曲线半径成正、反比,相关数据改变幅度与曲线半径成反比且当曲线半径超过800 m时基本收敛,此时可采用“以直代曲”的简化算法;曲线半径对于横向梁轨相互作用影响程度大于纵向,相较于挠曲、制动工况,伸缩工况受曲线半径影响更加显著;多荷载耦合作用下,采用传统线性叠加法相较于考虑加载历史更为保守且温度荷载起主要贡献;考虑加载历史时钢轨在往复荷载作用下会产生不可忽视的残余内力,且在循环荷载作用下将会产生收敛于第1次往复荷载下的残余内力,这是扣件纵向阻力的弹塑性滞回特性决定的;线性叠加法误差与曲线半径具有相关性,相较于挠曲、制动工况,伸缩工况下对其更为敏感。研究结果可为考虑加载历史下曲线桥梁结构设计提供参考。

超大粒径沥青混合料的黏弹特性及温度影响

为精准表征超大粒径沥青混合料(LSAM-50)柔性基层路面的动态黏弹力学响应,对LSAM-50进行动态模量试验,分析了温度对LSAM-50黏弹参数的影响,构建了基于广义对数Sigmoidal模型的黏弹参数主曲线以及基于广义Maxwell模型的黏弹性本构关系.结果表明:温度对LSAM-50黏弹参数的影响显著,温度升高后LSAM-50模量的变化由集料嵌挤力主导,动态模量与存储模量随着温度的升高逐渐降低后趋于稳定;由于LSAM-50具有更大的粒径和集料嵌挤力,其高温抗变形能力比AC-20和AC-13更强;可用广义Maxwell模型构建LSAM-50的黏弹本构关系,其相关性不低于0.99.

基于曲线拟合误差估计的阻抗优化识别方法

在雷达系统、舰船系统、数据中心等大型复杂系统中,供配电系统变流器端口阻抗信息的完整、快速、准确获取,是研判系统可靠性的重要基础。现有研究大都使用分段线性拟合值方法进行阻抗识别,不仅需要大量阻抗测量才能获得完整的阻抗特性,并且可能因过度测量而对系统的正常运行造成干扰。针对这些问题,从阻抗特性曲线的非线性拟合入手,提出一种“非线性曲线拟合、全局误差估计、优选测量点频率”的阻抗识别方法,实现基于曲线拟合误差估计的测量点优化选择,以较少阻抗测量代价获取宽频带阻抗特性。与现有的方法相比,所提方法更有助于测量点的合理选择、阻抗谐振峰的准确识别,从而更高效地实现宽频带阻抗的识别,为复杂供配电系统运行状况的研判提供可靠依据。算例仿真证实了所提方法的有效性。

“两尘四气”空气污染数据的校准模型

通过Excel软件对监测点收集的空气质量数据进行拆分及构造函数的方法,拟合了“两尘四气”的六个方程,这些方程可用于对自建点数据进行校准。在对所收集的数据标准化后,利用SPSS软件对“两尘四气”数据误差产生的原因进行回归分析,建立了多元线性回归方程。方程显示:压强、温度和风速更容易导致自建点数据误差,可使用对上述三种因素不敏感的材质制造检测仪的传感器。以上使用Excel和SPSS软件对大数据进行比对处理及建模的方法可用于环境监测、农业生产等领域促进高质量生态文明建设。

两条B样条曲线求交的高效计算方法

曲线曲面间求交计算在CG和CAD中有着广泛的应用.牛顿法等迭代法计算效率高但需要良好的初始值;裁剪法具有良好的鲁棒性但计算效率不理想,尤其是对于相切情况的求交问题.为此,提出一种计算2条B样条曲线交点的混合方法.首先提出一种高效的线性复杂度裁剪方法,用于获得良好的初始值;然后提出一种与导数无关且效率更高的改进的割线法,用于验证贯穿性相交情况;最后提出一个相切情况下收敛阶为2的迭代公式,其性能远优于现有的牛顿法和裁剪法.理论上,混合方法若与根隔离法相结合,可以应用于更多类型曲线间的求交问题.数值实验结果表明,与现有的同类方法相比,在贯穿情况下,所提方法的计算效率提高约10%,在相切情况下则提高约100%~300%.

微动技术在轨道交通勘察地质分层中的应用

城市轨道交通一般处于城市中心,对于勘察钻孔和布设大范围的微动台阵有很多的不便和限制。本文提出利用微动技术的线性台阵,沿城市道路方向布设检波器,减少了占地范围,为道路地下地质分层提供了丰富的频散曲线信息。研究表明,线性台阵利用多通道采集技术,获得多个勘探点的数据,通过频散曲线的拐点、斜率和频散点疏密进行分层,与已知钻孔资料对比后,确定了方法的可靠性。本文以南京某在建地铁为例,结合附近运营线路钻孔资料和微动技术勘测资料,为在建补充地质勘察工作提供了依据,相比钻孔成果微动技术更能揭露地下复杂地层的分布,提高了工程地质勘察精度和效率,缩减了勘察成本和工期。

利用简化曲线交会法初步确定HDPE土工膜厚度

采用曲线交会法确定平原水库库盘土工膜厚度时,存在材料特性曲线难获得、需多次读图取数、重复试验次数多、可选择性小等不便之处。为此,基于曲线交会法的基本原理和材料弹性阶段的线弹性与双曲线应力-应变本构关系,推导了初步确定高密度聚乙烯(HDPE)土工膜厚度的简化曲线交会法(包括简化线弹性法和简化双曲线法),并对新疆某平原水库HDPE土工膜厚度的选取进行了计算分析。结果表明:(1)与曲线交会法相比,简化曲线交会法计算误差较小,拉应力安全系数误差平均约为2.22%,应变安全系数误差平均约为-4.24%,说明该方法较为准确合理;(2)当其他条件相同时,正方形孔隙拉应力安全系数最低,以其为该工程安全运用的判断基准;(3)对同一孔隙条件,安全系数随土工膜厚度增加而增加,且呈近似线性关系;(4)通过计算得到满足安全系数要求的HDPE土工膜厚度范围为≥0.5 mm。简化曲线交会法有助于土工膜厚度确定时的便捷计算,可以满足工程设计阶段初步确定HDPE土工膜厚度的要求。

高速公路线形设计研究

高速公路线形设计是高速公路建设中的关键环节,其设计质量直接关系到道路的安全性、舒适性和经济性。论文阐述了高速公路线形设计的基本理论,包括高速公路线形设计基本概念、基本原则及影响因素,讨论了高速公路线形设计要点,包括平面线形、纵断面和平纵面设计。

基于线性强化结构应变法的低周疲劳分析

焊接结构的低周疲劳分析对于轨道车辆尤为重要。为了有效评估焊接结构的低周疲劳,提出一种基于线性强化本构的结构应变数值计算方法。该方法基于经典板壳理论和弹塑性力学。通过考虑材料的应变硬化行为,将材料的真实应力应变关系简化为线性强化本构关系。利用有限元分析软件ABAQUS和Fe-safe计算焊接结构焊趾位置的结构应力,给出基于径向回退算法的线性强化本构塑性修正模型。利用MATLAB编写结构应变数值计算程序对结构应力进行塑性修正,并计算结构应变。基于该结构应变,给出了考虑板厚效应和载荷模式的等效结构应变范围计算公式,利用主应变-寿命曲线分析低周疲劳数据,建立了广泛用于轨道车辆的Q450高强度耐候钢材料制成的3种焊接接头的有限元模型。采用结构应力法的主应力-寿命曲线和结构应变数值计算方法的主应变-寿命曲线对试验获得的疲劳数据进行分析,并对比2种方法计算的等效结构应变范围。结果表明,各焊接接头的试验数据均分布在主应变-寿命曲线的线性窄带内,验证了结构应变数值计算法的可行性;与结构应力法相比,结构应变数值计算方法能更好地反映低周疲劳过程中材料的应变硬化现象,更适用于焊接结构的低周疲劳评估。该方法对轨道车辆焊接板结构的低周疲劳评估具有研究价值。与传统的通过提取节点力的方式计算结构应力和结构应变参数的方法相比,利用MATLAB编写结构应变数值计算程序极大地提高了结构应变参数计算的效率。