Numerical optimisation and experimental validation of divided rail freight brake disc crown

In this study, numerical optimisation and experimental validation of a divided rail freight brake disc crown made of grey cast iron EN-GJL-250 is presented.The analysed brake disc is used in rail freight wagons and possesses a load capacity of 22.5 tons per axle. Two of the divided rail freight brake discs are mounted on each axle.With the aid of numerical analysis, the thermal dissipation properties of the brake disc were optimised and ventilation losses were reduced, and the numerical results were compared with experimental results. A one-way fluid–structure interaction analysis was performed. A computational fluid dynamic model of a divided rail freight brake disc, used to predict air flow properties and heat convection, was incorporated into a finite element model of the disc and used to evaluate the temperature of the disc. A numerical parametrical optimisation of cooling ribs of the brake disc was also performed, and novel optimised cooling ribs were developed. A transient thermal numerical analysis of the brake disc was validated using temperature measurements obtained during a braking test on a test bench. The ventilation losses of the brake disc were measured on a test bench specifically designed for the task, and the losses were compared to the simulation results. The experimentally obtained ventilation losses and temperature measurements compared favourably with the simulation results, confirming that this type of simulation process may be confidently applied in the future. Through systematic optimisation of the divided rail freight brake disc, ventilation losses were reduced by 37% and the mass was reduced by 21%, resulting in better thermal performance that will bring with it substantial energy savings.

Numerical simulation of blasting effect with divided charge structure

This paper numerically simulates the stress development and generates a three-dimensional model of the medium-length hole blasting in infinite rock mass for continuous charge and divided charge in blasting by using the large-scale nonlinear dynamic analysis software LS-DYNA and the elastic-plastic model ~*MAT_PLASTIC_KINEMATIC and JWO-EOS.The differences of the decreasing rate in Von Mises effective stress of blasting,element effective stress peak of free surface,bore wall stress and acceleration are investigated.It is shown that divided charge could greatly improve the blasting effect by engineering blasting practice.

一种Divided RESURF高压互连结构研究

高压互连是功率集成电路中的重要技术,随着PIC在结构功能上的发展和应用范围上的增大,人们对功率集成电路中的高压互连技术的要求也与日俱增。围绕高压互连技术进行研究,使用Divided RESURF技术设计一种横向双扩散金属氧化物半导体场效应晶体管,通过进行二维仿真,优化其结构和掺杂浓度等参数,器件的击穿耐压达到903 V,可用于600 V高压集成电路中。

Generation of tool path for flank milling in divided areas

Presents the division of non developable ruled surface into divided small areas and flank milling in these divided areas to improve machining efficiency and machined surface quality by controlling the machining error for each area, and the algorithms developed for generation of tool path and calculation of errors, and concludes from computer simulation results that the algorithms are correct.

Second-order divided difference filter for vision-based relative navigation

A second-order divided difference filter (SDDF) is derived for integrating line of sight measurement from vision sensor with acceleration and angular rate measurements of the follower to estimate the precise relative position,velocity and attitude of two unmanned aerial vehicles (UAVs).The second-order divided difference filter which makes use of multidimensional interpolation formulations to approximate the nonlinear transformations could achieve more accurate estimation and faster convergence from inaccurate initial conditions than standard extended Kalman filter.The filter formulation is based on relative motion equations.The global attitude parameterization is given by quarternion,while a generalized three-dimensional attitude representation is used to define the local attitude error.Simulation results are shown to compare the performance of the second-order divided difference filter with a standard extended Kalman filter approach.

Square-root divided difference Rauch-Tung-Striebel smoother

A square-root version of the divided difference Rauch-Tung-Striebel (RTS) smoother is proposed in this paper. The square-root variant essentially propagates the square roots of the covariance matrices and can consistently improve the numerical stability because all the resulting covariance matrices are guaranteed to stay positive semi-definite. Furthermore, the square-root form ensures reliable implementation in an embedded system with fixed or limited precision although it is algebraically equivalent to the standard form. The new smoothing algorithm is tested in a challenging two-dimensional maneuvering target tracking problem with unknown and time-varying turn rate, and its performance is compared with that of other de-facto standard filters and smoothers. The simulation results indicate that the proposed RTS smoother markedly outperforms the associated filters and gives slightly smaller error than an unscented-based RTS smoother.

Hierarchical robot control structure and Newton's divided difference approach to robot path planning

A hierarchical robot control is proposed for robot soccer system. The Newton’s divided difference is utilized in robot path planning. This paper describes the problems encoutered, software design considerations, vision algorithm and controls of individual robots. The solutions to the problems implemented are simple and direct. It is observed that many of the ideas and solutions can be evolved based on simple theories and concepts. This paper focuses on software structure of multi agent controls, vision algorithm and simple path planning method.

A Nonstationary Halley’s Iteration Method by Using Divided Differences Formula

This paper presents a new nonstationary iterative method for solving non linear algebraic equations that does not require the use of any derivative. The study uses only the Newton’s divided differences of first and second orders instead of the derivatives of (1).

Application of Adaptive Divided Difference Filter on GPS/IMU Integrated Navigation System

The efficient and accurate approximate nonlinear filters have been widely used in the estimation of states and parameters of dynamical systems. In this paper, an adaptive divided difference filter is designed for precise estimation of states and parameters of micromechanical gyro navigation system. Based on the investigation of nonlinear divided difference filter the adaptive divided difference filter(ADDF) was designed, which takes account of the incorrect time-varying noise statistics of dynamical systems and compensation of the nonlinearity effects neglected by linearization. And its performance is superior to that of DDF and extended Kalman filter(EKF). Simulation results indicate that the advantages of the proposed nonlinear filters make them attractive alternatives to the extended Kalman filter.

Speed prediction models for car and sports utility vehicleat locations along four-lane median divided horizontal curves

Sites with varying geometric features were analyzed to develop the 85 th percentile speed prediction models for car and sports utility vehicle(SUV) at 50 m prior to the point of curvature(PC), PC, midpoint of a curve(MC), point of tangent(PT) and 50 m beyond PT on four-lane median divided rural highways. The car and SUV speed data were combined in the analysis as they were found to be normally distributed and not significantly different. Independent parameters representing geometric features and speed at the preceding section were logically selected in stepwise regression analyses to develop the models. Speeds at various locations were found to be dependent on some combinations of curve length, curvature and speed in the immediately preceding section of the highway. Curve length had a significant effect on the speed at locations 50 m prior to PC, PC and MC. The effect of curvature on speed was observed only at MC. The curve geometry did not have a significant effect on speed from PT onwards. The speed at 50 m prior to PC and curvature is the most significant parameter that affects the speed at PC and MC, respectively. Before entering a horizontal curve, drivers possibly perceive the curve based on its length. Longer curve encourages drivers to maintain higher speed in the preceding tangent section. Further, drivers start experiencing the effect of curvature only after entering the curve and adjust speed accordingly. Practitioners can use these findings in designing consistent horizontal curve for vehicle speed harmony.

The English-Chinese Translation Research of Divided We Stand from the Perspective of Translator Behavior Criticism

The paper is designed to research the translation practice of Divided We Stand from the perspective of Translator Behavior Criticism.Thus,the paper uses the tools of degree of truth-seeking,degree of utility and degree of rationality under the macro-guidance of Truth-seeking-Utility-attaining evaluative model of continuum.Specifically from the perspective of intra-translation,extra-translation and non-translation,the paper research and evaluate the translation practice.

Zero Divided by Zero Equals One

Objective: Accumulating evidence indicates that zero divided by zero is equal to one. Still it is not clear what number theory or algebra is saying about this. Methods: To explore the relationship between the problem of the division of zero by zero and number theory, a systematic approach is used while analyzing the relationship between number theory and independence. Result: The theorems developed in this publication support the thesis that zero divided by zero is equal to one. Furthermore, it was possible to define the law of independence under conditions of number theory and algebra. Conclusion: The findings of this study suggest that zero divided by zero equals one.

Divided Loyalties

GUO Luping had to breakthe promise she made to her Tunisian patients. The Chinese obstetrician worked in Tunisia for 15 months on a Chinese medical aid program to the country. When she came back to her hometown in southeast China＇sJiangxi Province in 2016, she got bad news. The 41-year-old doctor was diagnosed with mid-to-late-stage breast cancer. Having helped countless patients abroad, the doctor now had to care about her own health.

Ultrapulse carbon dioxide laser excision as a novel treatment for large divided nevus of the eyelid

Aims:Divided nevus of the eyelid is a congenital pigmented nevus that impacts eyelid function and aesthetics.While surgical excision and laser ablation are current treatment options,they have limitations when dealing with large lesions.This study aims to investigate the efficacy and safety of carbon dioxide(CO₂)laser excision treatment for divided nevus of the eyelid.Methods:This retrospective study included 10 patients(5 males,5 females)with a mean age of 23.7 years(9-54 years).All underwent CO₂laser excision and were followed up for 12 months.Treatment outcomes were assessed through clearance and recurrence rates,evaluated using digital photography.Postoperative complications were closely monitored throughout the 12-month follow-up period.Patient satisfaction was assessed using a comprehensive questionnaire.Results:All patients presented with unilateral divided nevus of the eyelid,with lesion diameters ranging from 25 to 50 mm and heights ranging from 0.3 to 6 mm(mean:3.93 mm).Patients received between 1 and 5 laser treatment sessions.At the 12-month follow-up,a 100%clearance rate was achieved,with no recurrence observed in any patient.All patients maintained a continuous eyelid margin with acceptable irregularity.Complications were minimal,with partial eyelash loss in 8 patients,hyperpigmentation in 2 patients,and mild upper eyelid trichiasis in 1 patient.No severe complications,such as ectropion,eyelid margin notching,corneal erosion,or significant scar hypertrophy,were reported.All patients expressed being"very satisfied"with the functional and cosmetic outcomes in a questionnaire.Conclusions:CO₂laser excision offers a simple,precise,and effective treatment approach for divided nevus of the eyelid.This innovative technique simplifies the treatment process,achieves excellent cosmetic outcomes,and eliminates the need for skin grafting,making it a promising option for the management of large divided nevus.

Neural mechanisms of top-down divided and selective spatial attention in visual and auditory perception

Top-down attention mechanisms require the selection of specificobjects or locations;however,the brain mechanism involved when attention is allocated across different modalities is not well understood.The aim of this study was to use functional magnetic resonance imaging to define the neural mechanisms underlyingdivided and selective spatial attention.A concurrent audiovisual stimulus was used,and subjects were prompted to focus on a visual,auditory and audiovisual stimulus in a Posner paradigm.Ourbehavioral results confirmed the better performance of selectiveattention compared to devided attention.We found differences in the activation level of the frontoparietal network,visual/auditorycortex,the putamen and the salience network under differentattention conditions.We further used Granger causality(GC)toexplore effective connectivity differences between tasks.Differences in GC connectivity between visual and auditory selective tasksreflected the visual dominance effect under spatial attention.In addition,our results supported the role of the putamen inredistributing attention and the functional separation of the saliencenetwork.In summary,we explored the audiovisual top-down allocation of attention and observed the differences in neuralmechanisms under endogenous attention modes,which revealedthe differences in cross-modal expression in visual and auditory attention under attentional modulation.

Meromorphic Functions of Finiteφ-order and Linear Askey-Wilson Divided Difference Equations

The growth of meromorphic solutions of linear difference equations containing Askey-Wilson divided difference operators is estimated.Theφ-order is used as a general growth indicator,which covers the growth spectrum between the logarithmic orderρlog(f)and the classical orderρ(f)of a meromorphic function f.

基于归一分解的并行多目标Dividing Rectangles算法

多目标优化问题普遍存在且难以解决,目前多采用多目标进化算法进行求解.然而,这些方法通常在种群初始化阶段和进化过程中包含随机操作以保持多样性,导致了其结果不可复现且缺乏全局收敛的理论保证.鉴于此,提出了一种基于归一分解的多目标Dividing Rectangles(DIRECT)算法,首先通过一种可较好捕捉复杂前沿的归一分解方法将原问题分解为一系列子问题,以降低问题计算复杂度;其次,采用Dividing Rectangles算法同时优化分解得到的子问题,并在优化过程中基于全局关联机制将生成的候选解分配给相应的子问题,以更好地保留优秀候选解并提高算法搜索效率;最后,证明了算法的收敛性.此外,为了进一步提高计算效率,提出了一种基于自适应关联迁移策略的多层次多粒度并行方案,并基于该方案对所提出的算法进行了并行化.将所提算法应用于多个基准优化问题,实验结果表明,相比于NSGA-II,所提串行算法能够产生收敛性、多样性更为优越的帕累托最优解集,并行算法可在大规模缩短问题求解时间的同时,进一步提升帕累托前沿近似精度.

Does digitalization mitigate regional inequalities?Evidence from China

Regional inequality significantly influences sustainable development and human well-being.In China,there exists pronounced regional disparities in economic and digital advancements;however,scant research delves into the interplay between them.By analyzing the economic development and digitalization gaps at regional and city levels in China,extending the original Cobb-Douglas production function,this study aims to evaluate the impact of digitalization on China's regional inequality using seemingly unrelated regression.The results indicate a greater emphasis on digital inequality compared to economic disparity,with variable coefficients of 0.59 for GDP per capita and 0.92 for the digitalization index over the past four years.However,GDP per capita demonstrates higher spatial concentration than digitalization.Notably,both disparities have shown a gradual reduction in recent years.The southeastern region of the Hu Huanyong Line exhibits superior levels and rates of economic and digital advancement in contrast to the northwestern region.While digitalization propels economic growth,it yields a nuanced impact on achieving balanced regional development,encompassing both positive and negative facets.Our study highlights that the marginal utility of advancing digitalization is more pronounced in less developed regions,but only if the government invests in the digital infrastructure and education in these areas.This study's methodology can be utilized for subsequent research,and our findings hold the potential to the government's regional investment and policy-making.

ON THE DIVIDED DIFFERENCE FORM OF FAA DI BRUNO＇S FORMULA

The n-divided difference of the composite function h ：= f o g of functions f, g at a group of nodes t0,t1,…,tn is shown by the combinations of divided differences of f at the group of nodes g（t0）,g（t1）,…,g（tm） and divided differences of g at several partial group of nodes t0,t1,…,tn, where m = 1,2,…,n. Especially, when the given group of nodes are equal to each other completely, it will lead to Faà di Bruno＇s formula of higher derivatives of function h.

Some results on numerical divided difference formulas

The remainder estimates of numerical divided difference formula are given for the functions of lower and higher smoothness, respectively. Then several divided difference formulas with super-convergence are derived with their remainder expressions.