Research on the longitudinal protection of a through-type cophase traction direct power supply system based on the empirical wavelet transform

This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a distinctive boundary structure.This approach capitalizes on the boundary’s capacity to attenuate the high-frequency component of fault signals,resulting in a variation in the high-frequency transient energy ratio when faults occur inside or outside the line.During internal line faults,the high-frequency transient energy at the checkpoints located at both ends surpasses that of its neighboring lines.Conversely,for faults external to the line,the energy is lower compared to adjacent lines.EWT is employed to decompose the collected fault current signals,allowing access to the high-frequency transient energy.The longitudinal protection for the traction network line is established based on disparities between both ends of the traction network line and the high-frequency transient energy on either side of the boundary.Moreover,simulation verification through experimental results demonstrates the effectiveness of the proposed protection scheme across various initial fault angles,distances to faults,and fault transition resistances.

Traction power systems for electrified railways:evolution,state of the art,and future trends

Traction power systems(TPSs)play a vital role in the operation of electrified railways.The transformation of conventional railway TPSs to novel structures is not only a trend to promote the development of electrified railways toward high-efficiency and resilience but also an inevitable requirement to achieve carbon neutrality target.On the basis of sorting out the power supply structures of conventional AC and DC modes,this paper first reviews the characteristics of the existing TPSs,such as weak power supply flexibility and low-energy efficiency.Furthermore,the power supply structures of various TPSs for future electrified railways are described in detail,which satisfy longer distance,low-carbon,high-efficiency,high-reliability and high-quality power supply requirements.Meanwhile,the application prospects of different traction modes are discussed from both technical and economic aspects.Eventually,this paper introduces the research progress of mixed-system electrified railways and traction power supply technologies without catenary system,speculates on the future development trends and challenges of TPSs and predicts that TPSs will be based on the continuous power supply mode,employing power electronic equipment and intelligent information technology to construct a railway comprehensive energy system with renewable energy.

Pars plana vitrectomy with internal limiting membrane plugging assisted by autologous blood for optic disc pit associated with vitreomacular traction

Dear Editor,We report a case of optic disc pit(ODP)associated with vitreomacular traction which has been successfully treated by a combined technique.We have obtained the written informed consent from the patient,and this case study is in accordance with the tenets of the Declaration of Helsinki.

A Loss-model-based Efficiency Optimization Control Method for Induction Traction System of High-speed Train under Emergency Self-propelled Mode

Increasing attention has been paid to the efficiency improvement of the induction traction system of high-speed trains due to the high demand for energy saving. In emergency self-propelled mode, however, the dc-link voltage and the traction power of the motor are significantly reduced, resulting in decreased traction efficiency due to the low load and low speed operations. Aiming to tackle this problem, a novel efficiency improved control method is introduced to the emergency mode of high-speed train traction system in this paper. In the proposed method, a total loss model of induction motor considering the behaviors of both iron and copper loss is established. An improved iterative algorithm with decreased computational burden is then introduced, resulting in a fast solving of the optimal flux reference for loss minimization at each control period. In addition, considering the parameter variation problem due to the low load and low speed operations, a parameter estimation method is integrated to improve the controller's robustness. The effectiveness of the proposed method on efficiency improvement at low voltage and low load conditions is demonstrated by simulated and experimental results.

Effect of endoscopic full-thickness resection assisted by distal serosal turnover with floss traction for gastric submucosal masses

BACKGROUND Complex and high-risk surgical complications pose pressing challenges in the clinical implementation and advancement of endoscopic full-thickness resection(EFTR).Successful perforation repair under endoscopy,thereby avoiding surgical intervention and postoperative complications such as peritonitis,are pivotal for effective EFTR.AIM To investigate the effectiveness and safety of EFTR assisted by distal serosal inversion under floss traction in gastric submucosal tumors.METHODS A retrospective analysis of patients with gastric and duodenal submucosal tumors treated with EFTR assisted by the distal serosa inversion under dental floss traction from January 2023 to January 2024 was conducted.The total operation time,tumor dissection time,wound closure time,intraoperative bleeding volume,length of hospital stay and incidence of complications were analyzed.RESULTS There were 93 patients,aged 55.1±12.1 years.Complete tumor resection was achieved in all cases,resulting in a 100% success rate.The average total operation time was 67.4±27.0 min,with tumor dissection taking 43.6±20.4 min.Wound closure times varied,with gastric body closure time of 24.5±14.1 min and gastric fundus closure time of 16.6±8.7 min,showing a significant difference(P<0.05).Intraoperative blood loss was 2.3±4.0 mL,and average length of hospital stay was 5.7±1.9 d.There was no secondary perforation after suturing in all cases.The incidence of delayed bleeding was 2.2%,and the incidence of abdominal infection was 3.2%.No patient required other surgical intervention during and after the operation.CONCLUSION Distal serosal inversion under dental-floss-assisted EFTR significantly reduced wound closure time and intraoperative blood loss,making it a viable approach for gastric submucosal tumors.

Generalized autoencoder-based fault detection method for traction systems with performance degradation

Fault diagnosis of traction systems is important for the safety operation of high-speed trains.Long-term operation of the trains will degrade the performance of systems,which decreases the fault detection accuracy.To solve this problem,this paper proposes a fault detection method developed by a Generalized Autoencoder(GAE)for systems with performance degradation.The advantage of this method is that it can accurately detect faults when the traction system of high-speed trains is affected by performance degradation.Regardless of the probability distribution,it can handle any data,and the GAE has extremely high sensitivity in anomaly detection.Finally,the effectiveness of this method is verified through the Traction Drive Control System(TDCS)platform.At different performance degradation levels,our method’s experimental results are superior to traditional methods.

Laparoscopic Orchidopexy after 4 Weeks of Testicular Traction with Preservation of Blood Supply: A New Concept for the Treatment of Intra-Abdominal Cryptorchidism: Original Article

Background: Testicular atrophy is recurrent after orchidopexy for intra-abdominal cryptorchidism due to damage to vessels. Fowlers-Stephens and Shehata methods proposed staged orchidopexy, but are still associated to a rate of atrophy greater than 10%. Purpose: We set out to present a new technique that preserves testicular vessels. Our study is aimed at investigating testicular vitality after surgery. Patients and Method: We reviewed files of boys who underwent orchidopexy for 2 years in our department. Those who have been operated for intra-abdominal cryptorchidism with the new technique and aged between 6 months and 14 years old were included in our study. We excluded boys who have been operated before 6 months and after 14 years old and those who did not respect their follow-up plane. Ultrasound (US) outcomes were used to measure testicular volumes and blood flow at each postoperative visit. The Sample population was divided into group A and group B representing testes that were followed respectively for 12 and 24 months. Results: 22 boys with 25 testes were included in our study;11 testes in group A and 14 testes in group B. In each group, we noted a significant difference of UDT volumes from the third month after surgery with respective P-values 0.05. There was no statistical difference between UDT and contra lateral testes volumes 12 months after surgery in group A and 24 months in group B with respective P-values of 0.07 and 0.72. All volume differential indexes were Conclusion: This method offers a new perspective in performing safe orchidopexy for intra abdominal undescended testes.

Lasting Attraction

High-level opening up and policies to attract foreign direct investment(FDI)were hot topics during the annual sessions of the National People’s Congress(NPC)and the Chinese People’s Political Consultative Conference(CPPCC)National Committee,China’s key annual political meetings commonly known as Two Sessions.

Device-assisted traction methods in colorectal endoscopic submucosal dissection and options for difficult cases

Endoscopic submucosal dissection(ESD)procedure has a longer procedure time and higher perforation rate than endoscopic mucosal resection owing to technical complications,including a poor field of vision and inadequate tension for the submucosal dissection plane.Various traction devices were developed to secure the visual field and provide adequate tension for the dissection plane.Two randomized controlled trials demonstrated that traction devices reduce colorectal ESD procedure time compared with conventional ESD(C-ESD),but they had limitations,including a single-center fashion.The CONNECT-C trial was the first multicenter randomized controlled trial comparing the C-ESD and traction device-assisted ESD(T-ESD)for colorectal tumors.In the T-ESD,one of the device-assisted traction methods(S-O clip,clip-with-line,and clip pulley)was chosen according to the operator’s discretion.The median ESD procedure time(primary endpoint)was not significantly different between C-ESD and T-ESD.For lesions≥30 mm in diameter or in cases treated by nonexpert operators,the median ESD procedure time tended to be shorter in T-ESD than in C-ESD.Although T-ESD did not reduce ESD procedure time,the CONNECT-C trial results suggest that T-ESD is effective for larger lesions and nonexpert operators in colorectal ESD.Compared with esophageal and gastric ESD,colorectal ESD has some difficulties,including poor endoscope maneuverability,which may be associated with prolonged ESD procedure time.T-ESD may not effectively improve these issues,but a balloon-assisted endoscope and underwater ESD may be promising options and these methods can be combined with T-ESD.

Advances in traction methods for endoscopic submucosal dissection:What is the best traction method and traction direction?

Endoscopic submucosal dissection(ESD)has been developed as a treatment for superficial gastrointestinal neoplasms,which can achieve en bloc resection regardless of the lesion size.However,ESD is technically difficult because endoscopists cannot bring their hand into the gastrointestinal tract,unlike surgeons in regular surgery.It is difficult to obtain sufficient tension in the dissection plane and a good field of vision.Therefore,ESD is associated with a long procedure time and a high risk of adverse events in comparison with endoscopic mucosal resection.Traction methods have been developed to provide sufficient tension for the dissection plane and a good field of vision during the ESD procedure.However,traction direction is limited in most traction methods,resulting in insufficient effect in some cases.Although traction direction is considered important,there have been few investigations of its effect.In the first half of this review,important traction methods are discussed,including traction direction.In second half,appropriate traction methods for each organ are considered.Other important considerations for traction method,such as ability to adjust traction strength,interference between traction device and endoscope,and the need for specialized devices are also discussed.

Two traction methods that can facilitate esophageal endoscopic submucosal dissection

Different traction devices that can provide a visual field and attain appropriate tension at the dissection plane during endoscopic submucosal dissection(ESD)have been developed.Clip-with-line(CWL)is a classic traction device that can offer per-oral traction toward the direction where the line is drawn.A multicenter randomized controlled trial(CONNECT-E trial)comparing the conventional ESD and CWL-assisted ESD(CWL-ESD)for large esophageal tumors was conducted in Japan.This study showed that CWL-ESD was associated with a shorter procedure time(defined as the time from initiating submucosal injection to completing tumor removal)without increasing the risk of adverse events.Multivariate analysis revealed that whole-circumferential lesion and abdominal esophageal lesion were independent risk factors for technical difficulties,which were defined as a procedure time of>120 min,perforation,piecemeal resection,inadvertent incision(any accidental incision caused by the electrosurgical knife within the marked area),or handover to another operator.Therefore,techniques other than CWL should be considered for these lesions.Several studies have shown the usefulness of endoscopic submucosal tunnel dissection(ESTD)for such lesions.A randomized controlled trial conducted at five Chinese institutions showed that compared with the conventional ESD,ESTD had a significantly reduced median procedure time for lesions covering≥1/2 of the esophageal circumference.In addition,a propensity score matching analysis conducted at a single Chinese institution showed that compared with the conventional ESD,ESTD had a shorter mean resection time for lesions at the esophagogastric junction.With the appropriate use of CWL-ESD and ESTD,esophageal ESD can be performed more efficiently and safely.Moreover,the combination of these two methods may be effective.

Cooling System Design Optimization of an Enclosed PM Traction Motor for Subway Propulsion Systems

This paper presents the design optimization of a self-circulated ventilation system for an enclosed permanent magnet(PM)traction motor utilized in the propulsion systems for subway trains.In order to analyze accurately the machine's inherent cooling capacity when the train is running,the ambient airflow and the related heat transfer coefficient(HTC)are numerically investigated considering synchronously the bogie installation structure.The machine is preliminary cooled with air ducts set on the motor shell,and the fluidic-thermal field distributions with only the shell air duct cooling are numerically calculated.During simulations,the HTC obtained in the former steps is applied to the external surface of the machine to model the inherent cooling characteristic caused by the train movement.To reduce the temperature rise and thus guarantee the motor's working reliability,an internal self-circulated air cooling system is proposed according to the machine temperature distribution.The air enclosed in the end-caps is driven by the blades mounted on both sides of the rotor core and forms two air circuits to bring the excessive power losses generated in the heating components to cool regions.The fluid flow and temperature rise distributions of the cooling system's structural parameters are further improved by the Taguchi method in order to confirm the efficacy of the internal air cooling system.

Visualized analysis of research on myopic traction maculopathy based on CiteSpace

AIM:To analyze the global scientific output concerning myopic traction maculopathy(MTM)and to summarize the research frontiers and hot topics of MTM related researches.METHODS:Data were collected for bibliometric and visualization analyses from Web of Science(WOS)Core Collection.Exported records were analyzed for titles,publication years,research institutions,journal names,authors,keywords,and abstracts using CiteSpace software version 6.1.RESULTS:A total of 839 related studies were analyzed,the publication volume increased annually,with Asia the most active region of MTM research.Optical coherence tomography angiography,optical coherence tomography,macular hole,high myopia,macular buckling were identified as the focus of the current research.Progression,association,classification and shape were identified as the major research frontiers.CONCLUSION:MTM is a major cause of visual loss in pathological myopic eyes.During the preceding 17y,the number of annual publications in MTM research increased gradually.Studies on the progression nature of MTM,genome-wide association study and proper classification of MTM might still be the frontiers of MTM researches.

Damage to the External Genitalia by Traction Following Assault and Battery at the C.H.U Gabriel Touré: About a Case

Trauma to the external genitalia by tearing is rare. We report the case of a 30-year-old patient, admitted to the emergency room for trauma of the external genitalia by traction following a blow and intentional injury. The authors highlight the lesions that can occur during this type of trauma and insist on the systematic search for urethral and cavernous lesions. Conclusion: Trauma to the external genitalia by intentional assault and battery is rare in our context. They occur most often in a young person and are frequently associated with damage to the corpora cavernosa and urethra.

Optimal traction direction in traction-assisted gastric endoscopic submucosal dissection

Various traction devices have been developed to secure a visual field and sufficient tension at the dissection plane during endoscopic submucosal dissection(ESD).However,few large-scale studies have investigated the effectiveness of traction devices in gastric ESD.Clip-with-line(CWL)is one such traction device that is widely used in cases of gastric ESD.The CONNECT-G trial was the first multicenter randomized controlled trial to compare conventional ESD with CWLassisted ESD(CWL-ESD)for superficial gastric neoplasms.Overall,no significant intergroup difference was observed in terms of the gastric ESD procedure time.However,subgroup analysis according to lesion location revealed a significant reduction in the procedure time of gastric ESD for the lesion located at the greater curvature of the middle and upper third of the stomach in the CWL-ESD group.In this subgroup analysis,lesion location was categorized as follows:anterior wall,posterior wall,lesser curvature,and greater curvature of the upper,middle,and lower thirds of the stomach.However,the gastric ESD procedure time showed no significant difference,except for lesions located at the greater curvature of the upper and middle thirds of the stomach.The traction direction of CWL in the stomach was limited to the cardia and changed depending on the lesion location.Therefore,outcomes of the CONNECT-G trail suggest that the effectiveness of CWL was influenced by lesion location,i.e.,traction direction.Further studies are warranted to investigate the optimal traction direction in gastric ESD.

Time Series as an Aid to Research of Traction Substation Load

In the case of electric or tram traction vehicles, the energy for propulsion purposes, as well as all other purposes, is processed and delivered via traction substations. Knowledge of the course of traction substation loading, especially at the stage of its design, is an extremely important issue because of the choice of the processing equipment of the main circuit or protection devices. In the range of investigations of railway traction substation B in vicinity of Cracow （Poland）, the measurements of current load in hours 4：00 a.m.-8：00 p.m. were realized. The measurements for the analysis were chosen from those realized between 6：00 a.m.-8：00 a.m. （the morning rush time）. Due to the sampling of 2 h summit with a frequency of 2 kHz, the recorded data set contains 1.44 ~ 107 elements. Therefore, the necessary transformation of data was to lower frequency 1 Hz, 10 Hz and 50 Hz. The results of the analysis presented below indicate the effect of such conduct on the obtained results for the parameters of time series models. In view of the unsatisfactory effects of the polynomial approximation, there is a need to seek a more efficient approximation method for achieving the optimum compatibility with the measured process. Continued research should lead to the formulation of procedures, which will determine an acceptable accuracy of the expected variability of traction substation loads.

Experimental research on grouser traction of deep-sea mining machine

The traction characteristics of the grouser, cutting the simulative soil of deepsea sediment, with different tooth widths, tooth heights, and ground pressures are studied with traction characteristic test apparatus. A traction-displacement model is obtained by combining the analysis of the cutting mechanism. The results show that the tractiondisplacement curves of grousers with different tooth widths, tooth heights, and ground pressures have the same changing trend, which matches the Wong traction model. Their sensitivity coefficient and shear modulus are slightly fluctuated. Therefore, the average values can be used as the traction model parameters. The maximum traction of the grouser with a two-side edge and a 10 mm tooth width increment changing with the tooth height and ground pressure can be determined according to the grousers with different tooth widths. By combining the traction model parameters, the traction-displacement curve of the grouser with a certain group values of tooth width, tooth height, and ground pressure can be predicted. Therefore, the slip of the mining machine can be prevented to improve the mining efficiency.

Industrial frequency single-phase AC traction power supply system for urban rail transit and its key technologies

To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail transit. The proposed system consists of a main substation （MSS） and cable traction network （CTN）. The MSS includes a single-phase main traction transformer and a negative-se- quence compensation device, while the CTN includes double-core cables, traction transformers, overhead catenary system, rails, etc. Several key techniques for the proposed system were put forward and discussed, which can be summarized as （1） the power supply principle, equivalent circuit and transmission ability of the CTN, the cable-catenary matching technique, and the selection of catenary voltage level; （2） the segmentation technology and status identification method for traction power supply network, distributed and centralized protection schemes, etc.; （3） a power supply scheme for single-line MSS and a power supply scheme of MSS shared by two or more lines. The proposed industrial frequency single-phase AC traction power supply system shows an excellent technical performance, good economy, and high reliability, hence provides a new alternative for metro and urban rail transit power supply systems.

APPLICATION OF IMPROVED EMD IN VIBRATION SIGNAL FEATURE EXTRACTION OF VEHICLE

In order to truly obtain the feature extraction of vibration signals under the strong background noise, the analysis and improvement of empirical mode decomposition （EMD） is carried on. After that, the improved EMD is applied to the feature extraction of vehicle vibration signals. First, the multi-autocorrelation method is adopted in each input signal,so the noise is reduced effectively. Then, EMD is used to deal with these signals,and the intrinsic mode functions （IMFs） are obtained. Finally, for obtaining the feature information of these signals, the Hilbert transformation and the spectrum analysis are performed in some IMFs. Theoretical analysis and ex- periment verify the effectiveness of the method, which are valuable reference for the same engineering problems.

Scheme of long distance power supply for electrified railway traction network based on traction cable

Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.