Contact Relationships Research Articles

Research on the Experimental Control of Abnormal Vibration on High-Speed Lines

With the continuous increase of operational mileage of high-speed trains in China, wheel–rail wear and various dynamics problems are gradually being exposed. Abnormal vibration in the carbody appeared during operation. To solve this problem, the rail profiles, wheel profiles, and vehicle vibration acceleration were measured. A coupled rigid–flexible dynamic model of high-speed trains has been established. Through the analysis of the dynamic response, the causes of the abnormal vibrations of electric multiple units were studied. The results show that the equivalent conicity is 0.477 when the wear mileage is 100,000 km, and the 6–8 Hz bogie hunting frequency transmission to the carbody is the main factor that produces carbody shaking. Wheel re-profiling, improving line quality, and rail grinding are proposed to solve the problem of abnormal carbody shaking. Wheel re-profiling can effectively reduce the equivalent conicity. The personalized profile grinding method can improve the wheel/rail contact relationship. The bogie hunting frequency should be avoided to prevent resonance with the carbody’s first-order elastic mode. The machine tamping control also improves the stiffness under the rail and improves line geometric irregularity, combined with the function of the rail grinding, further eliminating carbody shaking.

The Impact of Hollow Wear on the Stability of High-Speed Railway Vehicles

Hollow wear on wheels is a common form of surface damage often observed in high-velocity vehicles. It is widely recognized that hollow wear of the wheel tread degrades the dynamic performance of rail vehicles, especially in the issue commonly referred to as “operational stability”, and leads to abnormal wheel–rail contact interactions. However, the evaluation criteria for vehicle stability are not uniform, which affects the assessment of wheel conditions and the timing of wheel re-profiling during maintenance. Therefore, numerical simulations were conducted by matching the measured worn wheel profiles with standard rails, and three different methods were employed to evaluate vehicle stability in this article. The numerical results revealed that the wheel equivalent conicity exhibits a nonlinear characteristic caused by hollow wear, which means that the nominal equivalent conicity is unable to accurately represent the geometric contact relationship between the wheel and rail. Under identical wheel wear conditions, a certain difference was observed in the critical speed of the vehicle determined by the velocity-reducing method and the bifurcation configuration method. Both methods were capable of reflecting the impact of wheel hollow wear on vehicle stability at the critical speed. Compared to the velocity-reducing method, the bifurcation configuration method can better reflect the transition process of a vehicle from stable running to hunting instability. Furthermore, the lateral vibration acceleration values measured above the bogie frame indicated that slight wheel wear is insensitive to increased speed. However, when the wear was severe, the lateral vibration acceleration of the bogie was found to increase sharply, exceeding the established stability criteria. This phenomenon was consistent with the safety alarms that occurred during actual vehicle operation, indicating that the vehicle had failed to meet stability requirements.

Evaluation of the effectiveness of panoramic radiography in impacted mandibular third molars on deep learning models developed with findings obtained with cone beam computed tomography.

The aim of this study is to determine the contact relationship and position of impacted mandibular third molar teeth (IMM3) with the mandibular canal (MC) in panoramic radiography (PR) images using deep learning (DL) models trained with the help of cone beam computed tomography (CBCT) and DL to compare the performances of the architectures. In this study, a total of 546 IMM3s from 290 patients with CBCT and PR images were included. The performances of SqueezeNet, GoogLeNet, and Inception-v3 architectures in solving four problems on two different regions of interest (RoI) were evaluated. The SqueezeNet architecture performed the best on the vertical RoI, showing 93.2% accuracy in the identification of the 2nd problem (contact relationship buccal or lingual). Inception-v3 showed the highest performance with 84.8% accuracy in horizontal RoI for the 1st problem (contact relationship-no contact relationship), GoogLeNet showed 77.4% accuracy in horizontal RoI for the 4th problem (contact relationship buccal, lingual, other category, or no contact relationship), and GoogLeNet showed 70.0% accuracy in horizontal RoI for the 3rd problem (contact relationship buccal, lingual, or other category). This study found that the Inception-v3 model showed the highest accuracy values in determining the contact relationship, and SqueezeNet architecture showed the highest accuracy values in determining the position of IMM3 relative to MC in the presence of a contact relationship.

A comprehensive guide to food allergy management for the general pediatrician.

A comprehensive guide to food allergy management for the general pediatrician.

Analysis of the risk of interproximal contact loss between adjacent teeth and implant-supported fixed prostheses: A retrospective cross-sectional study.

Analysis of the risk of interproximal contact loss between adjacent teeth and implant-supported fixed prostheses: A retrospective cross-sectional study.

Unraveling the tectonic tapestry of granitic rocks: Petrogenetic insights from Triassic silicic plutonic and volcanic magmatism in the northern Tibetan Plateau

The petrogenetic typology of granites and their volcanic equivalents is crucial for understanding petrogenesis, but their magma sources and tectonic settings remain controversial. To clarify the relationship between granite typology and magma sources as well as geodynamic settings, an integrated study was conducted on the Keri silicic volcanic and plutonic rocks in the East Kunlun orogenic belt, northern Tibetan Plateau. Field geology and geochronology reveal that the ca. 208 Ma rhyolitic volcanic rocks directly overlie the ca. 228 Ma syenogranite pluton, which indicates that the East Kunlun orogenic belt underwent rapid uplift between 228 Ma and 208 Ma. The syenogranites show high silica and strongly peraluminous compositions (SiO2 = 76.45−78.96 wt%, A/CNK = 1.08−1.23), and enrichment in light rare earth elements [(La/Yb)N = 4.53−12.37] with negative Eu anomalies (Eu/Eu* = 0.08−0.56), similar to highly fractionated S-type granites. They exhibit enriched Sr-Nd-Hf isotopes [87Sr/86Sr = 0.7071−0.7089, εNd(t) = −5.73 to −6.83, εHf(t) = −8.33 to −1.45], which suggests an origin from the partial melting of Mesoproterozoic metagreywacke. Conversely, the rhyolitic volcanic rocks display A1-type granite affinities [i.e., 10,000*Ga/Al = 3.34−4.88; (Zr + Nb + Ce + Y) = 440−853 ppm; Y/Nb = 0.21−0.76] and weakly enriched or depleted Sr-Nd isotopes [87Sr/86Sr = 0.7066−0.7073, εNd(t) = −2.41 to −2.92; εHf(t) = 0.17−3.17], with high Nb-Ta contents (average of Nb = 94.74 ppm; Ta = 6.38 ppm). Petrogenetic and geochemical modeling indicate that these A1-type rhyolitic volcanic rocks were derived from Nb- and Ta-enriched oceanic-island basalt−like basaltic magmas that underwent extensive differentiation with minor crustal contamination. This study not only reveals a tectonic transition in the East Kunlun orogenic belt from syn-collisional compression to postcollisional extension during 228−208 Ma, but also demonstrates that the genetic types of granitic rocks are primarily controlled by their magma sources and magmatic evolution rather than tectonic settings. While a single granite rock may not precisely constrain the tectonic setting, the assemblage of diverse granite types with unique contact relationships holds significant tectonic implications.

Analysis of the wear performance of with thin flange wheel for high-speed trains

Purpose The wheel wear of high-speed trains is the main concern in the operation process of the high-speed trains. Wheel reprofile usually adopts the thin flange wheel profiles for the economic wheel reprofile strategy; however, the wheel wear evolution law of the thin flange wheel profile is not clear. The purpose of this paper mainly researches the wheel wear evolution law of thin flange wheel profile and the influence factors of thin flange wheel. Design/methodology/approach To solve this problem, this paper analyzed the wheel-rail contact relationship and established a vehicle dynamic model of high-speed train. The Jendel wheel wear model was used to analyze the evolution of thin flange wheel wear and rail deviation affecting wheel wear under thin flange wheel profiles. Findings Due to the consistency of the tread area, the distribution of wheel-rail contact points for thin flange wheels in the tread area is close. As the wheel flange increases, wheel wear also increases. Thin flange wheel profiles reduce wheel wear to a certain extent. The maximum wheel wear depths with rail deviations of −0.4 mm, 0 mm and 0.4 mm are 0.9844 mm, 1.077 mm and 1.142 mm, respectively. The negative rail deviation suppresses wheel wear, but the positive rail deviation increases wheel wear. Originality/value The evolution of wheel wear for thin flange wheels after reprofiling is not clear. This paper analyzed the wear characteristics of thin flange wheel wear and rail deviation affecting wheel wear under thin flange wheels. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2024-0401/

Intrinsic Topological Relationship between Pier Settlement Amplitude and Train Running Performance Dynamic Index

This study develops the train sub-model by multibody dynamic theory and establishes the longitudinally connected ballastless track-bridge sub-model using finite element theory. The two sub-models are assembled into a joint simulation model of train–track–bridge system coupling dynamic (JSTTBS) through wheel–rail contact relationships. Then, the influence of interlayer connection failure and pier settlement on the dynamic index of train–track–bridge system is analyzed, the intrinsic topological relationship (ITR) between pier settlement amplitude and dynamic index considering interlayer connection failure is proved, and the pier settlement threshold is proposed. The results showed that the calculation results of JSTTBS considering the interlayer connection failure and pier settlement are in good agreement with the literature data, verifying the model’s accuracy. The void beneath the slab caused by the pier settlement aggravates the train dynamic index change. After considering the void beneath the slab, the maximum value of each dynamic index is about two times that without accounting for the void. The uneven settlement value of the pier derived from the ITR is within 22.47[Formula: see text]mm, which is in good agreement with the calculation result of the established JSTTBS of 23.08[Formula: see text]mm, indicating the reliability of the ITR to calculate the uneven settlement threshold of the pier.

Characteristics of Organic Matter Types and Organic Matter Pore Development in Marine–Continental Transitional Shale

ABSTRACTThe types of organic matter (OM) significantly impact the hydrocarbon generation potential, reservoir capacity and mechanical properties of shale. Unlike the relatively homogeneous OM in high‐maturity marine shale (predominantly solid bitumen), marine–continental transitional shale exhibits a more complex OM assemblage, comprising a mixture of marine and terrestrial kerogen (vitrinite, inertinite and liptinite) and solid bitumen. Accurate differentiation of OM types and quantification of their associated pores are critical for evaluating the reservoir properties of transitional shale formations. This study investigates the Upper Carboniferous Taiyuan Formation shale in the Ningwu Basin, a representative marine–continental transitional system. A correlative microscopy approach integrating scanning electron microscopy (SEM) and optical microscopy was employed to classify OM types, which was further augmented by image segmentation processing techniques to elucidate their pore development characteristics. It reveals disparities in pore development associated with different OM types and proposes an SEM–based identification method for distinguishing them. Results indicated that vitrinite has thick cell walls with vertical fractures, a low grayscale value and a carbon content ranging from 80% to 95%; inertinite has thinner walls with distinct protrusions, a slightly higher grayscale value than vitrinite and carbon content between 75% and 90%; liptinite often retains the morphology of residual vegetation, such as serrated cutinite, flat ring‐like sporinite and lens‐like structured alginite. Solid bitumen has the highest grayscale value and is amorphous in shape. The development of OM pores is significantly related to the OM type, with the most developed pores found in solid bitumen, which is secondary in origin. This is followed by vitrinite and inertinite, with both secondary and primary pores present. The development of pores in OM is also related to the degree of thermal evolution and the types of surrounding minerals and contact relationships. The Taiyuan Formation transitional shale in the Ningwu Basin exhibits a wide range of total organic carbon (TOC) contents, with an average of 2.14%. Its microscopic components are primarily vitrinite and inertinite (over 50%), with a low degree of thermal maturity (average 1.17%) and low content of rigid minerals (average 42.3%), resulting in poorly developed OM pores and primarily intergranular pores in the storage spaces. However, the high organic carbon content and the strong adsorption capacity of vitrinite still endow the reservoir with the ability to enrich shale gas. The transitional shale possesses unique geological features, including interspersed thin coal seams and sandstone layers. The coal generates hydrocarbons and supplies gas in conjunction with shale, whereas thin sand layers enhance the reservoir capacity of the Taiyuan Formation shale, harbouring the potential for large‐scale gas reserves. Thus, an integrated exploration and exploitation model involving coal, shale and tight sandstone is recommended to maximise the resource potential of marine–continental transitional shale.

Panoramic radiographic features for machine learning based detection of mandibular third molar root and inferior alveolar canal contact.

This study uses machine learning (ML) to elucidate the contact relationship between the mandibular third molar (M3M) and the inferior alveolar canal (IAC), leading to three major contributions; (1) The first publicly accessible PR image dataset with semantic annotations for 1,478 IACs and M3Ms from 1,010 patients is introduced, which includes challenging cases, such as false positive contacts, with CBCT images as the gold standard, (2) Established radiological indicators for M3M-IAC contact were extracted as features using digital image processing, and these features were used as inputs for various ML methods. Eligibility was assessed through statistical analysis and radiologists evaluations. Clinical feedback from radiologists on these features provides insights for future improvements. (3) ANNs, two custom CNNs, seven established DL models, and their combinations were used for automatic M3M-IAC contact determination with extracted features, semantic annotations, and ROIs. The ANN configuration surpassed both radiologists and DL models in specificity (82%), F1 score (92%), and accuracy (85%), while maintaining a comparable sensitivity (86%) to the DL models. This indicates that ANNs can effectively predict M3M-IAC contact relations and are particularly effective at identifying cases with no contact relation between M3M and IAC compared to other ML methods. Future work should focus on developing automated segmentation algorithms for M3M and IAC on PRs, to identify relevant anatomical structures, thereby improving clinical usability. The dataset, feature extraction, and ML codes are available through the CONTACT grand challenge.

A cross-sectional study on improving clinical efficiency through centralized digital impression.

This study aims to explore the effect of improving clinical efficiency by replacing traditional impression workflow with centralized digital impression workflow. The department of prosthodontics in Center of Stomatology, Peking University Shenzhen Hospital has improved the clinical workflow by replacing the traditional impression made by doctors using impression materials for each patient with a centralized digital impression made by one technician for all patients in the department. This cross-sectional study recorded the chairside time required for impression taking in patients undergoing single posterior zirconia full crown restoration before clinical process improvement; the time required for centralized digital impression production; the comfort level of patients; and the adjacency relationship, occlusal contact relationship, and time required for prostheses adjusting (i.e., whether centralized digital impressions would compromise the quality of pro-stheses and increase the time of prostheses adjusting). The average time to make a traditional impression was (9.98±1.41) min, and the average time required for each patient to make a centralized digital impression was (5.98±1.49) min, which was shorter than that to used make a traditional impression (P<0.05). Centralized digital impression made patients feel more comfortable compared with traditional impression (P<0.05). The adjacency relationship of restorations by centralized digital impression was more appropriate (P<0.05), and no significant difference in occlusal relationship was found (P>0.05). The time required for adjusting prostheses also had no significant differences (P>0.05). Centralized digital impression can improve clinical efficiency for patients undergoing single posterior zirconia crown restoration. The time for impression taking is shorter, and patients feel more comfortable without compromising the quality of the prostheses.

P-271. Contact Patterns of United States Health Care Workers at Quaternary Health Center: Stability of contacts during the post-pandemic era

Abstract Background We lack understanding of how health care workers’ (HCWs) contacts change over time or in response to pandemics. This study describes the social contact patterns of HCWs in a large United States health care system via standardized social contact diaries. Mean number of total contacts over time (Jan 2021-May 2022): The mean contacts noted with dark-blue line with 95% confidence intervals (95%CI) in dark gray. The dashed black line shows the linear regression of contacts over time. The-axis is interrupted as the study was closed in June and July 2021. Methods Inpatient and outpatient HCWs enrolled from October 2020 to June 2022. Participants completed a monthly survey of all contacts during a single representative working day selected by the participant. Direct contact was defined as being within 2 meters of another person. Indirect contact was defined as being in the same room but more than 2 meters. In June 2022, participants completed a 2-day individual-level contact diary. We generated age-stratified contact matrices. Contacts were described by contact type, duration and contact relationship. Number and duration of contacts by job were compared by chi-squared test and number of contacts over time by linear regression. Average contacts of health care worker with all individuals The individual tiles color and numeric fill denote the average number of contacts per HCW of that age range with a contact of that age range. A horizontal marginal histogram shows the age break down of HCW participants and a vertical marginal histogram shows the resulting distribution of contact’s ages. Results 360 HCWs enrolled, 95 completed 1 or more monthly contact diary and 88 completed the intensive 2-day diary. The total number of contacts was stable over time (β0.14, p 0.20, Fig.1). HCWs reported direct contacts with less than 5 patients, 5-9 patients, 10-19 patients or 20 more patients, 50%, 29%,15% or 6% of the time respectively. HCWs reported direct contact with less than 5 other HCWs, 6-10 HCWs, 11-20 or 21 or more 19%, 39%, 27 % or 15% of the time respectively. In the June 2022, a total of 2,550 contacts were reported, 1,592 (62%) were with HCWs, and 570 (22%) with patients. Social workers, rehab/transport and doctors were more likely to have contact with 20 or more patients vs. other professions. Nurses, imaging technologists and rehab/transport were more likely to spend 20 minutes or more with patients vs. other professions. Contact matrices were not age assortative with HCWs having similar contacts across all working ages (Fig. 2). HCWs’ physical contacts focused on extremes of age (Fig. 3). Contact type varied by job with nearly all groups having more contacts with colleagues than patients (Fig, 4). Average physical contacts of HCWs per day: The The individual tiles color and numeric fill denote the average number of physical contacts per HCW of that age range with a contact of that age range. A horizontal marginal histogram shows the age break down of HCW participants and a vertical marginal histogram plot the resulting distribution of contact’s ages. Conclusion HCW contacts concentrated in their work environment and most contacts were focused in the working-age population. These contacts were stable over time even in the COVID-19 pandemic response. HCWs were 2.8 time more likely to contact HCWs than patients. Number of contacts of 2 days by participant job and contact individual Grouped box plots show the number of contacts over the 2-day intensive diary by HCW job (x-axis) and the HCWs relationship with the contact (e.g. colleague, patient or other). Disclosures Lauren Pischel, MD, Auxa Health: Advisor/Consultant Amyn Malik, MBBS, MPH, PhD, Analysis Group, Inc: Former Employee. We consulted with Pharma and Biotech on different research studies Ben Lopman, PhD, Epidemiological Research and Methods, LLC: Advisor/Consultant|Hillevax, Inc: Advisor/Consultant Albert I. Ko, MD, Merck: Grant/Research Support|Regeneron: Grant/Research Support Saad Omer, MBBS MPH PhD, Meta: Advisor/Consultant|Meta: Grant/Research Support

Train axlebox bearing composite fault denoising method based on SVMD and dual threshold classification criteria

Abstract The increase in train operating speed and the alteration of the wheel-rail contact relationship, which have resulted in a deterioration of the service conditions of axlebox bearings, render the composite bearing failure characteristics susceptible to being obliterated by robust background noise. In order to effectively filter out redundant noise and accurately extract the fault characteristics, a dual-threshold signal denoising method is constructed based on successive variational mode decomposition (SVMD) and combining the Euclidean distance and kurtosis characteristic (Dual-EDK). The validity of the proposed method is effective by the composite fault data of axlebox bearings on the equal scale test bench. Firstly, the signal is adaptively decomposed into K components by SVMD, which are classified into three categories by Dual-EDK: effective IMF, noisy IMF and noise IMF. Then, the effective IMF is retained, while the noisy IMF is discarded. Wavelet soft threshold (WST) is employed to reduce the noisy IMF, reconstruct effective IMF and denoising noisy IMF, and envelope demodulation is used to achieve noise reduction. Finally, the composite fault signals at both normal operating speeds and critical speed of instability are collated and subjected to analysis by the test bench. This is done in order to ascertain the efficacy of the proposed method by comparing the results with those obtained through the traditional approach. The results of the analysis demonstrate that, in comparison to VMD, the SNR is enhanced by 27.6% and the&amp;#xD;RMSE is diminished by 7.4% at normal operating speeds, the SNR is augmented by 26.2% and the RMSE is reduced by 9.6% at the unstable critical speed. These outcomes illustrate that the proposed method is capable of effectively extracting the denoising characteristic components of bearing faults, and that it has a pronounced impact.&amp;#xD;

A Study on the Residual Oil Distribution in Tight Reservoirs Based on a 3D Pore Structure Model

A tight reservoir is characterized by low porosity and permeability as well as a complex pore structure, resulting in low oil recovery efficiency. Understanding the micro-scale distribution of residual oil is of great significance for improving oil production and water flooding recovery rates. In this study, a 3D pore structure model of tight sandstone was established using CT scanning to characterize the residual oil distribution after water flooding. The effects of displacement methods and wettability on residual oil distribution at the micro-scale were then studied and discussed. Moreover, increasing the displacement rate has little effect on the distribution area and dominant seepage channels. Microscopic residual oil is classified into five discontinuous phases according to the oil–water–pore–throat contact relationship. The microscopic residual oil exhibits characteristics of being dispersed overall but locally concentrated. Under water-wet conditions, the injected water tends to strip the oil phase along the pore walls. Under oil-wet conditions, the pore walls have an improved adsorption capacity for the oil phase, resulting in a large amount of porous and membranous residual oil retained in the pores, which leads to a decrease in the overall recovery rate.

Efficacy of a deep learning system for automatic analysis of the comprehensive spatial relationship between the mandibular third molar and inferior alveolar canal on panoramic radiographs.

Efficacy of a deep learning system for automatic analysis of the comprehensive spatial relationship between the mandibular third molar and inferior alveolar canal on panoramic radiographs.

An Improved Multi-point Chord Reference Measurement Device and Error Correction Method for Corrugation Measuring in Sharp Curves

Background: The traditional chord reference method and its device have faced challenges matching the sharp curve track. Thus, it is of utmost importance to research and develop a measurement device and method that can obtain accurate and comprehensive information regarding rail running band corrugation. Aims: It provides a solution for the measurement of the multi-point chord reference method on sharply curved rails and, at the same time, meets the demand for data richness and accuracy in theoretical studies on the causes of rail corrugation and wheel-rail contact relationships. Objective: This paper aims to research and design a measurement device based on the multi-point chord reference method for the rail running band corrugation. Meanwhile, the error in measuring the sharp curve rail is corrected and verified by simulation. Methods: The lateral information of rail running band is obtained by using a line laser profile sensor; the rail corrugation measurement model and error correction model of the rail running band area are established based on multi-point reference system; the simulation of the system model is carried out using Matlab; and the mechanical structure is built for static testing. Results: The measurement model based on the profile sensor and multi-point chord reference system can accurately obtain the rail corrugation waveform of any longitudinal measurement line in the running band area. The measurement results can be accurately corrected for a radius of 200m- 400m, the error parameters can be effectively improved, and the mechanical mechanism of the measurement system runs stably. Conclusion: The results show that the measurement model can accurately measure the rail corrugation of the sharp curve section, and the multi-waveform in the rail running band area has good measurement performance, but the mechanical structure can be optimized and improved in the light weight.

Agreement and Discrepancies of Maternal- and Self-Reported Psychopathology in Emerging Adults

Collateral reports on psychopathology improve clinical care and research. Previous research showed moderate agreement between adults’ self- and collateral reports. Factors associated with discrepancies in different age groups, especially the crucial period of emerging adulthood, are yet to be investigated. We examined mother-child agreement and factors associated with discrepancies in N = 256 mother-child dyads with emerging adult children (M = 22.3 years) who participated in a longitudinal prevention study (18-year follow-up). Children completed self-report measures on psychopathology (Adult Behavior Checklist, ASR), current psychological distress, and two individual items regarding the mother-child relationship and frequency of contact. Mothers reported on their children’s psychopathology (Adult Behavior Checklist, ABCL) and their own psychological distress. Children and mothers completed a half-structured clinical interview on mental disorders. Agreement between ASR and ABCL was moderate to high (r = .48 to .53). Both reports significantly correlated with children’s diagnoses based on the clinical interview (r = .37 to .58). When children reported higher levels of psychopathology, higher levels of current psychological distress were associated with larger mother-child discrepancies. When mothers reported higher levels of child psychopathology, higher levels of maternal psychological distress, lower relationship quality, and higher frequency of contact were associated with larger discrepancies. Mother-child agreement in emerging adulthood is comparable to agreement in adolescence and adulthood. Factors associated with discrepancies differ for higher maternal- vs. self-reported psychopathology. Maternal psychological distress is more relevant for informant discrepancies than maternal mental disorder diagnoses. Longitudinal studies are needed to enhance the understanding of informant discrepancies.

Switch Rail Reduction Value Deviation’s Impact on Wheel–Rail Dynamic Interaction and Its Efficient Identification Method: A Numerical and Experimental Study

Railway turnout is a critical railway infrastructure that guides trains in switching tracks. Over time, uneven rail wear can lead to switch rail reduction value (SRRV) deviation, a typical structural defect that compromises turnout functionality and jeopardizes train operation safety. Current SRRV deviation detection methods rely primarily on inefficient manual inspections, making it difficult to ensure operational safety. To address this issue, the study carried out a comprehensive investigation combining numerical and experimental analyses. First, a rigid–flexible coupled dynamics model of a vehicle-turnout system was developed to analyze the wheel–rail dynamic interaction forces and contact relationships under various SRRV deviation conditions. The results revealed that SRRV deviation significantly affects both wheel–rail interaction forces and the turnout structural irregularity wavelength. Thus, based on discrete wavelet transform (DWT), a wheel–rail force trend component was derived that can effectively analyze the turnout structural irregular wavelength, and the mapping relationship between SRRV deviation and the wheel–rail force trend component was then established. Finally, an efficient and accurate method for identifying SRRV deviation based on wheel–rail force trend component was proposed and validated using field-measured data from trains passing through turnouts. This study contributes to the timely detection of track defects, helping to prevent safety incidents during train operations.

Effectiveness of ongoing single dose rifampicin post-exposure prophylaxis (SDR-PEP) implementation under routine programme conditions-An observational study in Nepal.

Leprosy control remains a challenge in Nepal. Single-dose rifampicin post-exposure prophylaxis (SDR-PEP) shows promise in reducing leprosy incidence among contacts of index cases, contributing to reducing the transmission of Mycobacterium (M.) leprae. This study evaluates the effectiveness of routine SDR-PEP implementation in Nepal in addition to contact screening, focusing on its impact on reducing leprosy risk among contacts and potential population-level effects. We conducted a retrospective cohort study to compare leprosy case notification rates and leprosy risk among close contacts. We compared two districts implementing SDR-PEP (the intervention group) and two without (the comparator group). Data from 2015 onwards included demographics, index case types, and contact relationships. Statistical analyses, including Cox regression and Kaplan-Meier survival curves, assessed the impact of SDR-PEP implementation. All four districts showed a decrease in case notification rates since 2015, with the steepest decline in the intervention districts. The risk of developing leprosy among contacts was significantly lower in the intervention districts (HR 0.28, 95% CI 0.18-0.44). SDR-PEP offered 72% protection, consistent over time, as shown in Kaplan-Meier plots. The protective effect was equally strong in blood-related contacts (HR 0.29 versus 0.27 in others, p = 0.32), and the proportion of MB cases among incident cases was not significantly different post-PEP (51.4% vs. 53.6%, p = 0.82). This study demonstrates the substantial protective effect of integrating SDR-PEP in routine leprosy control programs with contact screening, significantly lowering leprosy risk among contacts. SDR-PEP is equally effective for blood-related contacts and does not preferentially prevent PB cases. While suggesting potential population-level impact, the study design does not allow for firm conclusions at this level. Further research is needed to fully assess SDR-PEP's effectiveness in diverse contexts and optimize its implementation. Integrating SDR-PEP within well-organized contact screening programs is effective and is expected to reduce leprosy transmission when applied as a rolling intervention.

Analysis of the load distribution law and influencing factors of large-load three-stage synchronous ball screw

Abstract Based on the Hertz contact theory, the contact relationship between adjacent balls and lead screw, and the nut raceways is established for a three-stage synchronous ball screw. A model of axial stiffness for the three-stage synchronous ball screw under large load is established. Considering both the axial stiffness of the screw and the deformation of the screw and nut, the distribution of working contact angles and loads of all balls in the three-stage ball screw is established. Taking a three-hinge-point erection mathematical model as an example, a transmission model of the three-stage synchronous ball screw is established, plan the erection trajectory, and analyze and calculate the deformation and force of the balls in the three-stage synchronous ball screw under different load conditions and the force of a single ball in the erection process. The calculation results show that, during the erection process, the load distribution, the radial clearance, the normal deformation between balls and screw and between balls and nut of different balls in each stage of the ball screw are different.