A Novel Model for Describing Rail Weld Irregularities and Predicting Wheel-Rail Forces Using a Machine Learning Approach

Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and deterioration.Few researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry irregularities.However,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric shape.In this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to Shanghai.The vertical dynamic forces in the time and frequency domains were compared under different running speeds.These forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed model.Finally,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is found.The results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the literature.The ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.

基于Reason模型的SIF-Q260型电子小肠镜故障原因分析

根据武汉大学中南医院内窥镜中心SIF-Q260型小肠镜故障率高且维修成本高的情况,应用Reason模型,从环境影响、不安全监督、不安全行为前兆及不安全行为4个层面分析造成SIF-Q260小肠镜故障的原因,针对各个层面故障原因,从定期培训以规范内窥镜的洗消及使用、设置专人管理内窥镜并定期对内窥镜使用洗消的规范性进行监督及评价、完善内窥镜监管系统3方面拟定改进措施,堵住系统“漏洞”,为内窥镜质量控制措施的制定提供依据,可预防和减少内窥镜故障的发生。

A Brief Analysis Reasons of English Shortening Words

Shortening is one of important word formations which demands attentions of both teachers and students. The paper first briefly introduces shortening words in English into clipped words, initialisms, acronyms and blends,and then it mainly explores the reasons why shortening words appear and become popular.

Characteristics and Reasons for Catchwords' Emergence

All social phenomena are,to some extent,determined by economy,and language is also under the leverage of economic factor.With the development of society,economy,science and economy,human interpretation and consciousness of their language have been greatly enhanced.The exploration of catchword can be developed from its definition,its characteristics and reasons for its emergence.

Reasons of Taoism in Robert Bly's Poetry

Bly's preference of Taoist thoughts to Western philosophy and ideology in his poetry has its deeper reasons. It is his secluded life attitude and his poetics construction that promote him to learn from the ancient Chinese poetry which contains adequate Taoist ideas.

STUDY ON WETLAND LOSS AND ITS REASONS IN CHINA

Wetlands are ecosystems with many f unctions.But the general public and government lack a comprehen-sive understanding of the importance of wetland benefits,thus making bl indly exploitation,wetland resour ces decreasing and losing biodiversity.So wetlands in China,as in most countries,have suffered heavily from the pressure o f develop-ment and have confronted with the thr eats of loss.The paper takes Sanjian g Plain marshes,lakes in the middle r eaches of the Changjiang(Yangtze)River,coastal wetlands and mangroves as cases to study wetland loss in China,and puts forward main existing reasons of wetland loss,such as blindly reclamati on and exploitation of wetland resou rces,over-exploitation of bio-resource s in wetland,etc.More recently,there has been a growing recognition of t he benefits of wetlands and a wide range of legal and regulatory initiatives have been undertaken which are designed to impro ve wetland management and conservation.On the basis of the above analysis,the paper brings forward some suggestions on wetland conservation.

Effect of temperature difference load of 32 m simply supported box beam bridge on track vertical irregularity

In order to study the effect of temperature difference load （TDL） along the vertical direction of a simply supported beam bridge section on the vertical irregularity, a rail-bridge-piers calculation model was established. Taking 32 m simply supported box beam bridge which is widely used in the construction of pas- senger dedicated line in China as an example, influences of the temperature variation between the bottom and top of the bridge, temperature curve index, type of temperature gradient, and beam height on track vertical irregularity were analyzed with the model. The results show that TDL has more effects on long wave track irregularity than on short one, and the wavelength mainly affected is approxi- mately equal to the beam span. The amplitude of irregu- larity caused by TDL is largely affected by the temperature variation, temperature curve index, and type of temperature gradient, so it is necessary to monitor the temperaturedistribution of bridges in different regions to provide accurate calculation parameters. In order to avoid the irregularity exceeding the limit values, the height of 32, 48, and 64 m simply supported box beam bridges must not be less than 2.15, 3.2, and 4.05 m, respectively.

Subway Embedded Track Geometric Irregularity Safety Limits

A coupling dynamic model of a subway train and an embedded track is established to study the safety limits of track irregularities.The simulated vehicle system was a 74-degrees of freedom multi-rigid body model,and the rail was a Timoshenko beam.The slab was a three-dimensional solid finite element model.The sensitive wavelength irregularity was first studied,and then the safety limit of the sensitive wavelength was analyzed.The wheel-rail lateral force exhibited a substantial effect on the track alignment and gauge irregularity safety limit.The wheel-rail vertical force and the rate of wheel load reduction significantly affected the height and cross-level irregularity safety limit.The results demonstrate that the safety limits of the alignment,gauge,height,and cross-level embedded track geometric irregularity are 5.3 mm,[−10.5,8]mm,5.6 mm,and 6 mm,respectively.

Railway subgrade thermal-hydro-mechanical behavior and track irregularity under the sunny-shady slopes effect in seasonal frozen regions

The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static irregularity in the slab track.Based on the hydraulics theory,a thermal-hydro-mechanical(THM)coupled model of frozen soil is established and verified.We explore the process and characteristics of the temperature field and deformation of soil during the freezing process of high-speed railway subgrades and analyze the track irregularity variation law of China Railway Track SystemⅢslab tracks under uneven frost heaving deformation.The results show that,because the left and right slopes of high-speed railway subgrade are exposed to different amounts of solar radiation,which is the key factor causing uneven frost heaving of subgrade.Different strike angles cause changes in temperature of the subgrade’s upper part and the frost heaving amount on the surface,leading to differences in the deformation of the slab track structure:Increased strike angle weakens the rail level irregularity of the down line and marginally increases the rail level irregularity of the up line,and these become consistent in north-south directions.Therefore,when selecting railway lines in seasonal frozen areas,the west-east direction should be avoided to prevent the extremes in sunny-shady slopes effect on subgrades.

Robust Spectral Estimation of Track Irregularity

Because the existing spectral estimation methods for railway track irregularity analysis are very sensitive to outliers, a robust spectral estimation method is presented to process track irregularity signals. The proposed robust method is verified using 100 groups of clean/contaminated data reflecting he vertical profile irregularity taken from Bejing-Guangzhou railway with a sampling frequency of 33 data every ~10 m, and compared with the Auto Regressive (AR) model. The experimental results show that the proposed robust estimation is resistible to noise and insensitive to outliers, and is superior to the AR model in terms of efficiency, stability and reliability.

Prevalence Reasons and Monitoring Countermeasures of Scab in Eastern Wheat Area of Jiangsu Province

With the increasing prevalence frequency and aggravating harm degree in the 21st century, wheat scab had become a recurrent disease in eastern wheat area of Jiangsu Province. This paper reviewed general occurrence situation of wheat scab in eastern Jiangsu, and summarized its occurrence characteristics in last decade. The disease prevalence was elaborated from the aspects of fungal source quantity, chmatic conditions, cultivation modes, variety resistance and pesticide resistance. The author put forward a series of measures and countermeasures, including strengthening resistance monitoring and early warning, promoting and cultivating disease-resistant varieties, compressing planting area of direct seeding rice, canting out chemical control scientifically, and realizing unified prevention and control, in order to provide a scientific basis for the control of wheat scab.

Reasons for Permanent Tooth Extraction in the West of Kabul

Background: There has been no study in Kabul on reasons for permanent tooth extraction. This study aimed to determine the prevalence and reasons for tooth loss in a sample from two dental clinics in the west of Kabul. Methods: During a 6-month period (April-September 2019), the reasons for every extraction of a permanent tooth were recorded. Different reasons for tooth extraction were assigned, such as, dental caries, periodontal disease, eruption problems, trauma, orthodontics and others. The data requested for each extraction were: patient age, gender, previous treatment, educational level, type of tooth removed and the reason for its extraction. Results: young people aged between 20 - 29 years old had the highest percentage of extraction. Periodontal disease (39%) followed by caries (20%) was the most common reason for tooth extraction. Maxillary and mandibular first molars were removed most frequently (31%). 29% of patients have treated their teeth before extraction and RCT (Root Canal Treatment) (19%) is the most common previous treatment. Tooth loss has an opposite relationship with education level. People with high education level, loose their tooth less (14%). Conclusion: periodontal disease was the most common reason for tooth loss in Kabul, Afghanistan and a high percentage of tooth loss is seen among young people. Educating and preventive programs need to be implemented in order to reduce tooth loss.

Reasons for Delayed Breastfeeding Initiation among Newly Delivered Women in Two First-Category Hospitals in Yaoundé, Cameroon

Introduction: Exclusive breastfeeding is fundamental for the good health and development of the mother and the child. According to the World Health Organization (WHO), breastfeeding after childbirth should be initiated within 30 minutes. For a number of reasons, WHO recommendations on guiding principles for infants and young children feeding are often not followed. Objective: To determine the reasons for the delayed initiation of breastfeeding in newly delivered women. Means and Method: We carried out a mixed cross-sectional study over a period of six months from December 1st 2018 to May 31st 2019, at the Yaoundé Gynaeco-Obstetric and Pediatric Hospital. We included all mothers with full-term or premature babies weighing ≥ 2000 grams and those whom initiated breastfeeding more than one hour after delivery. The mother’s reasons for delaying breastfeeding initiation were recorded using a dictaphone and data were accurately extracted for analysis. Results: We interviewed 153 mothers. Their mean age was 27.9 ± 6.2 years. The main reasons for delaying breastfeeding initiation were caesarean delivery (22%), the belief in “spoiled milk” (21%), lack of knowledge about the time to initiate breastfeeding (21%), baby asleep (18%), and lack of instruction given to the mother by the health staff (2%). Conclusion: Delayed breastfeeding was common in our context. Improving the quality of breastfeeding involves communication, to break beliefs about spoiled milk, and strengthening mothers’ knowledge for optimal breastfeeding processes in accordance with WHO’s guidelines. The medical staff should anticipate and undertake the early initiation of breastfeeding in babies from mothers who deliver through caesarean section.

Reasons and Solutions of the Time-consuming College English Teaching with Low Efficiency

College English teaching has been regarded as time- consuming with low efficiency for a long time. This thesis proceeds with the entity of English education in China, deals with the main problems lying in the current college English teaching from 3 perspectives, including the nation and society, teachers, and students, and provides 5 suggestions accordingly.

The effect of track alignment irregularity on wheel-rail contact geometry relationship in a turnout zone

The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wheel-rail geometry relationship with the trace line method. The profile of the key rail sections was matched by cubic spline curve, and the shape interpolation was realized in non-controlling sections. The results show that the roll angles at each typical section increases gradually with the enlargement of track alignment irregularity. When the flange contact occurs, the roll angle increases dramatically. Proper track alignment irregularity towards the switch rail improves the structure irregularity of the turnout.

Psychometric characteristics of the Reasons for Death Fear Scale among Iranian nurses

Objectives:Death fear is the main subject in thanatology.Several researchers have defined different reasons for fear of death.This study aimed to explore the performance of the Farsi version of the Reasons for Death Fear Scale(RDFS)among a convenience sample of Iranian nurses(n=106).Methods:The nurses were selected by the convenience sampling method and were asked to complete the RDFS,Death Concern Scale,Collett-Lester Fear of Death Scale,Death Anxiety Scale,Death Depression Scale,and Death Obsession Scale.Results:For the RDFS,the Cronbach's a coefficient was 0.90,and the 2-week test-retest reliability was 0.64.The RDFS was correlated at 0.34,0.39,0.50,0.35,and 0.39 to the above-mentioned five scales,indicating its good construct and criterion-related validity.Based on the exploratory factor analysis,the RDFS-identified four factors accounted for 66.20%of the variance and were labeled as"Fear of Pain and Punishment,""Fear of Losing Worldly Involvements,""Religious Transgressions and Failures,"and"Parting from Loved Ones."Conclusions:The RDFS presents good validity and reliability and can be used in clinical and research settings in Iran.

On Personal Reasons for Gatsby's Tragedy

The Great Gatsby is a tragedy of both Gatsby, an individual, and his generation. The times he is from is widely accepted as the cause of his tragedy. But he should also be blamed due to his idealism, and lack of moral sense. This paper tries to analyze the reasons of Gatsby's tragedy on his own part.

An Analysis of the Reasons for the Preservation of Hat Culture in Britain

As a famous and interesting symbol of Britain, hat culture has existed for a long period in history and British still retain wearing hats especially when they attend some grand activities up to date. Despite the increasing development of society and changing of people's conceptions, British people have never abandoned the hat wearing tradition. This paper will elaborately analyze the reasons for the preservation of hat culture in Britain from the aspects of historical, geographical, and social factors. And the conclusion will be come up that it is the attitude of British toward hat culture that has kept it alive till today.

A Study of Reasons That Wang Guowei Got a Bias against the TZ’u in Southern Sung Dynasty

Wang Guowei's bias against the TZ'u in Southern Sung Dynasty is a meaningful topic in literature. This paper aims to find the reasons of this bias based on Jen-Chien TZ'u-hua. We analyze the factors from two respects, the external influence and his internal preference, wishing to be able to find out real reasons.

Characterizing neural activities evoked by manual acupuncture through spiking irregularity measures

The neural system characterizes information in external stimulations by different spiking patterns. In order to examine how neural spiking patterns are related to acupuncture manipulations, experiments are designed in such a way that different types of manual acupuncture （MA） manipulations are taken at the ＇Zusanli＇ point of experimental rats, and the induced electrical signals in the spinal dorsal root ganglion are detected and recorded. The interspike interval （ISI） statistical histogram is fitted by the gamma distribution, which has two parameters： one is the time-dependent firing rate and the other is a shape parameter characterizing the spiking irregularities. The shape parameter is the measure of spiking irregularities and can be used to identify the type of MA manipulations. The coefficient of variation is mostly used to measure the spike time irregularity, but it overestimates the irregularity in the case of pronounced firing rate changes. However, experiments show that each acupuncture manipulation will lead to changes in the firing rate. So we combine four relatively rate- independent measures to study the irregularity of spike trains evoked by different types of MA manipulations. Results suggest that the MA manipulations possess unique spiking statistics and characteristics and can be distinguished according to the spiking irregularity measures. These studies have offered new insights into the coding processes and information transfer of acupuncture.