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 ...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.展开更多
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 ...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.展开更多
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...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.展开更多
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...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.展开更多
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 ...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.展开更多
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 ...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.展开更多
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 accuratel...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.展开更多
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 tractio...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.展开更多
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...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.展开更多
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 e...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.展开更多
Based on improved test rig with cooling system, the traction experiments for 4109 Chinese aviation lubricant are tested under various simulated working conditions. Both the experimental data thanks to their accuracy a...Based on improved test rig with cooling system, the traction experiments for 4109 Chinese aviation lubricant are tested under various simulated working conditions. Both the experimental data thanks to their accuracy and stability and the better cooling effect of the electric shafts has given the rationality of the experimental rig a strong support. An empirical equation for calculating the traction coefficient of 4109 lubricant, which may be conveniently used for engineering application,is obtained. Furthermore, the rheological properties of the lubricant are investigated.展开更多
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 pap...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.展开更多
Inrecent years,a series of cultural TV shows,including National Teasure,If National Treasures Could Speak and There is Something New in the Palace Museum, have increased the popularity of museum visits and changed the...Inrecent years,a series of cultural TV shows,including National Teasure,If National Treasures Could Speak and There is Something New in the Palace Museum, have increased the popularity of museum visits and changed the concept of audiences. Peo-ple's enthusiasm for enjoying cultural relics and visiting museums has been re-kindled.Museum tourism has become a new hot attraction for visitors.展开更多
In recent years, the broad application of optical coherence tomography and vitrectomy, combined with research efforts in maculopathy in high myopia have provided many achievements, such as the new classification of my...In recent years, the broad application of optical coherence tomography and vitrectomy, combined with research efforts in maculopathy in high myopia have provided many achievements, such as the new classification of myopic traction maculopathy (MTM). Here, we review the latest developments in the diagnosis and treatment of MTM, including its conception, clinical characteristics, pathogenesis, clinical stages, and the options for surgical treatment.展开更多
Endoscopic mucosal resection(EMR) is problematic with regard to en bloc and curable resection rates.Advancements in endoscopic techniques have enabled novel endoscopic approaches such as endoscopic submucosal dissecti...Endoscopic mucosal resection(EMR) is problematic with regard to en bloc and curable resection rates.Advancements in endoscopic techniques have enabled novel endoscopic approaches such as endoscopic submucosal dissection(ESD), which has overcome some EMR problems, and has become the standard treatment for gastrointestinal tumors. However, ESD is technically difficult. Procedure time is longer and complications such as intraoperative perforation and bleeding occur more frequently than in EMR. Recently various traction methods have been introduced to facilitate ESD procedures, such as clip with line, external forceps, clip and snare, internal traction, double scope, and magnetic anchor. Each method must be used appropriately according to the anatomical characteristics. In this review we discuss recently proposed traction methods for ESD based on the characteristics of various anatomical sites.展开更多
The traction capacity of the mining machine is greatly in?uenced by the traction rheological properties of the deep-sea sediments. The best simulative soil was prepared for substituting the deep-sea sediment based on ...The traction capacity of the mining machine is greatly in?uenced by the traction rheological properties of the deep-sea sediments. The best simulative soil was prepared for substituting the deep-sea sediment based on the deep-sea sediment collected from the Paci?c C-C mining area. Traction rheological properties of the simulative soil were studied by a home-made test apparatus. In order to accurately describe the traction rheological properties and determine traction rheological parameters, the Newtonian dashpot in Maxwell body of Burgers model was replaced by a self-similarity spring-dashpot fractance and a new rheological constitutive model was deduced by fractional derivative theory. The results show the simulative soil has obvious non-attenuate rheological properties. The transient creep and stable creep rate increase with the traction, but they decrease with ground pressure. The fractional derivative Burgers model are better in describing non-attenuate rheological properties of the simulative soil than the classical Burgers model. For the new traction rheological constitutive equation of the simulative soil, the traction rheological parameters can be obtained by ?tting the tested traction creep data with the traction creep constitutive equation. The ground contact length of track and walking velocity of the mining machine predicted by the traction rheological constitutive equation can be used to take full advantages of the maximum traction provided by the soil and safely improve mining effciency.展开更多
AIM: To describe the en bloc perfluorodissection(EBPD) technique and to demonstrate the applicabilityof using preoperative intravitreal bevacizumab duringsmall-gauge vitreoretinal surgery(23-gauge transconjunctival su...AIM: To describe the en bloc perfluorodissection(EBPD) technique and to demonstrate the applicabilityof using preoperative intravitreal bevacizumab duringsmall-gauge vitreoretinal surgery(23-gauge transconjunctival sutureless vitrectomy) in eyes with advancedproliferative diabetic retinopathy(PDR) with tractionalretinal detachment(TRD).METHODS: This is a prospective, interventional caseseries. Participants included 114(eyes) with advancedproliferative diabetic retinopathy and TRD. EBPD wasperformed in 114 eyes(consecutive patients) during23-gauge vitrectomy with the utilization of preoperativebevacizumab(1.25 mg/-0.05 mL). Patients mean age was 45 years(range, 21-85 years). Surgical time had a mean of 55 min(Range, 25-85 min). Mean follow up of this group of patients was 24 mo(range, 12-32 mo). Main outcome measures included best-corrected visual acuity(BCVA), retinal reattachment, and complications.RESULTS: Anatomic success occurred in 100%(114/-114) of eyes. Significant visual improvement [≥ 2 Early Treatment Diabetic Retinopathy Study(ETDRS) lines] was obtained in 69.2%(79/-114), in 26 eyes(22.8%) BCVA remained stable, and in 8 eyes(7%) BCVA decreased(≥ 2 ETDRS lines). Final BCVA was 20/-50 or better in 24% of eyes, between 20/-60 and 20/-400 in 46% of eyes, and worse than 20/-400 in 30% of eyes. Complications included cataract in 32(28%) eyes, iatrogenic retinal breaks in 9(7.8%) eyes, vitreous hemorrhage requiring another procedure in 7(6.1%) eyes, and phthisis bulbi in 1(0.9%) eye.CONCLUSION: This study demonstrates the usefulne-ss of using preoperative intravitreal bevacizumab and EBPD during smallgauge vitreoretinal surgery in eyes with TRD in PDR.展开更多
AIM:To investigate the affecting factors of parapapillary gamma and delta zones and other fundus morphological features in high myopia.METHODS:Seventy high myopia patients were included in this retrospective observati...AIM:To investigate the affecting factors of parapapillary gamma and delta zones and other fundus morphological features in high myopia.METHODS:Seventy high myopia patients were included in this retrospective observational study and 47 patients were female.Patients were divided into three groups:no posterior staphyloma(no PS),PS with myopic traction maculopathy(PS with MTM),and PS without MTM using 3-dimensional magnetic resonance imaging and optical coherence tomography.MTM patients were fur ther classified into three types[epiretinal membrane,macular hole,and macular retinoschisis(MRS)].Diameters of the gamma and delta zones were measured among other morphometric variables using fundus photographs.RESULTS:Of the 70 individuals(127 eyes),the mean age was 57.46±13.56y.In univariate analysis,morphological features changed most dramatically in PS with MTM patients,who had the largest gamma zone diameters,the largest disk-fovea distance(DFD)and disk-fovea angle,and the smallest angle kappa and vertical distance of temporal arterial arcade.However,their horizontal delta zone diameter was smaller than in the patients with PS yet without MTM.In multivariate analysis,with axial length(AL)and age adjusted,the horizontal diameter in the delta zone of the PS without MTM group was still significantly larger than in the PS with MTM group(P=0.024).Comparing the three subtypes of MTM patients,the diameters of the gamma zone and DFD in MRS group were the largest.CONCLUSION:The characteristics of the gamma and delta zones change inconsistently in different stages of high myopia.These changes may be associated with anatomical changes caused by local traction.Factors such as PS,AL and age play an important role.These findings may provide a hint about the pathogenesis of traction in high myopia.展开更多
BACKGROUND:Acupuncture and moxibustion against visceral noxious stimulation present different mechanisms in the peripheral and central nervous systems,involving release of neurotransmitter substance P,acetylcholine es...BACKGROUND:Acupuncture and moxibustion against visceral noxious stimulation present different mechanisms in the peripheral and central nervous systems,involving release of neurotransmitter substance P,acetylcholine esterase,leucine-enkephalin,and c-Fos protein expression.However,there are few reports addressing changes in neurotransmitter expression following manual acupuncture and electroacupuncture against visceral traction pain.OBJECTIVE:To explore changes in neurotransmitter expression in the ileum and protein expression in the medullary visceral zone of visceral traction pain rats undergoing pretreatment of emulational manual acupuncture,and to investigate the differences between emulational manual acupuncture and electroacupuncture.DESIGN,TIME AND SETTING:The randomized,controlled study was performed at the Biomedical Engineering Laboratory,Shanghai University of Traditional Chinese Medicine,Shanghai,China from August 2008 to July 2009.MATERIALS:G6805 electroacupuncture apparatus(Shanghai Medical Electronic Machine Factory,China) and ZSF-I acupuncture manipulation simulation therapeutic system(Chinese Medical Engineering Room,Shanghai University of Traditional Chinese Medicine,Shanghai China) were used in the present study.METHODS:A total of 40 male Sprague Dawley rats were equally and randomly assigned to sham surgery,model,emulational manual acupuncture and electroacupuncture groups.In the emulational manual acupuncture and electroacupuncture groups,emulational manual acupuncture and electroacupuncture were applied at bilateral Zusanli(ST 36) acupoints for 30 minutes,and models of visceral traction pain were established immediately.MAIN OUTCOME MEASURES:Substance P expression,c-Fos and glial fibrillary acidic protein expression were measured using immunohistochemistry.Acetylcholine esterase activity was examined utilizing a colorimetric method.Leucine-enkephalin content was detected using a radioimmune assay.Degree of pain in rats was assessed by pain score.RESULTS:Pain score,substance P expression in the ileum,acetylcholine esterase activity,expression of c-Fos protein and glial fibrillary acidic protein in the medullary visceral zone were significantly decreased following pretreatment of emulational manual acupuncture and electroacupuncture in rats with visceral traction pain(P < 0.05).Compared with the electroacupuncture group,the leucine-enkephalin content was significantly increased,and pain score was significantly diminished in the emulational manual acupuncture group(P < 0.05).CONCLUSION:Emulational manual acupuncture pretreatment decreases acetylcholine esterase activity,increases leucine-enkephalin release,downregulates expression of c-Fos protein and glial fibrillary acidic protein and ultimately inhibits visceral traction pain by reducing substance P release.The effectiveness in inhibiting visceral traction pain is greater when using emulational manual acupuncture compared with electroacupuncture.This is because emulational manual acupuncture effectively increases leucine-enkephalin release.展开更多
The traction motor is the power source of the locomotive.If the surface waviness occurs on the races of the motor bearing,it will cause abnormal vibration and noise,accelerate fatigue and wear,and seriously affect the...The traction motor is the power source of the locomotive.If the surface waviness occurs on the races of the motor bearing,it will cause abnormal vibration and noise,accelerate fatigue and wear,and seriously affect the stability and safety of the traction power transmission.In this paper,an excitation model coupling the time-varying displacement and contact stiffness excitations is adopted to investigate the effect of the surface waviness of the motor bearing on the traction motor under the excitation from the locomotive-track coupled system.The detailed mechanical power transmission path and the internal/external excitations(e.g.,wheel–rail interaction,gear mesh,and internal interactions of the rolling bearing)of the locomotive are comprehensively considered to provide accurate dynamic loads for the traction motor.Effects of the wavenumber and amplitude of the surface waviness on the traction motor and its neighbor components of the locomotive are investigated.The results indicate that controlling the amplitude of the waviness and avoiding the wavenumber being an integer multiple of the number of the rollers are helpful for reducing the abnormal vibration and noise of the traction motor.展开更多
基金supported in part by the Scientific Foundation for Outstanding Young Scientists of Sichuan under Grant No.2021JDJQ0032in part by the National Natural Science Foundation of China under Grant No.52107128in part by the Natural Science Foundation of Sichuan Province under Grant No.2022NSFSC0436.
文摘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.
文摘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.
文摘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.
文摘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.
文摘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.
基金Supported by Sichuan Administration of Traditional Chinese Medicine(No.2021MS422).
文摘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.
基金supported by the National Natural Science Foundation of China under Grant 52107007the China Scholarship Council under Grant 202008120084the“Chunhui Plan”Collaborative Research Project of Chinese Ministry of Education under Grant HZKY20220604。
文摘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.
文摘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.
文摘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.
文摘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.
基金This project is supported by National Natural Science Foundation of China !(19990514)
文摘Based on improved test rig with cooling system, the traction experiments for 4109 Chinese aviation lubricant are tested under various simulated working conditions. Both the experimental data thanks to their accuracy and stability and the better cooling effect of the electric shafts has given the rationality of the experimental rig a strong support. An empirical equation for calculating the traction coefficient of 4109 lubricant, which may be conveniently used for engineering application,is obtained. Furthermore, the rheological properties of the lubricant are investigated.
基金funded by Youth Science Foundation Fund Project of National Natural Science Foundation of China(51607148)Science and Technology R&D Program of China State Railway Group Co.,Ltd.(SY2020G001)Project of Sichuan Science and Technology Program(2021YJ0028)。
文摘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.
文摘Inrecent years,a series of cultural TV shows,including National Teasure,If National Treasures Could Speak and There is Something New in the Palace Museum, have increased the popularity of museum visits and changed the concept of audiences. Peo-ple's enthusiasm for enjoying cultural relics and visiting museums has been re-kindled.Museum tourism has become a new hot attraction for visitors.
文摘In recent years, the broad application of optical coherence tomography and vitrectomy, combined with research efforts in maculopathy in high myopia have provided many achievements, such as the new classification of myopic traction maculopathy (MTM). Here, we review the latest developments in the diagnosis and treatment of MTM, including its conception, clinical characteristics, pathogenesis, clinical stages, and the options for surgical treatment.
文摘Endoscopic mucosal resection(EMR) is problematic with regard to en bloc and curable resection rates.Advancements in endoscopic techniques have enabled novel endoscopic approaches such as endoscopic submucosal dissection(ESD), which has overcome some EMR problems, and has become the standard treatment for gastrointestinal tumors. However, ESD is technically difficult. Procedure time is longer and complications such as intraoperative perforation and bleeding occur more frequently than in EMR. Recently various traction methods have been introduced to facilitate ESD procedures, such as clip with line, external forceps, clip and snare, internal traction, double scope, and magnetic anchor. Each method must be used appropriately according to the anatomical characteristics. In this review we discuss recently proposed traction methods for ESD based on the characteristics of various anatomical sites.
基金Supported by the National Natural Science Foundation of China(Nos.11502226,51274251,51434002)the Key Research and Development Plan of Hunan Province(No.2017WK2032)+1 种基金the Research Foundation of Education Bureau of Hunan Province,China(Nos.15C1317,16C1542)the Hunan Provincial Innovation Foundation For Postgraduate(No.CX2017B342)
文摘The traction capacity of the mining machine is greatly in?uenced by the traction rheological properties of the deep-sea sediments. The best simulative soil was prepared for substituting the deep-sea sediment based on the deep-sea sediment collected from the Paci?c C-C mining area. Traction rheological properties of the simulative soil were studied by a home-made test apparatus. In order to accurately describe the traction rheological properties and determine traction rheological parameters, the Newtonian dashpot in Maxwell body of Burgers model was replaced by a self-similarity spring-dashpot fractance and a new rheological constitutive model was deduced by fractional derivative theory. The results show the simulative soil has obvious non-attenuate rheological properties. The transient creep and stable creep rate increase with the traction, but they decrease with ground pressure. The fractional derivative Burgers model are better in describing non-attenuate rheological properties of the simulative soil than the classical Burgers model. For the new traction rheological constitutive equation of the simulative soil, the traction rheological parameters can be obtained by ?tting the tested traction creep data with the traction creep constitutive equation. The ground contact length of track and walking velocity of the mining machine predicted by the traction rheological constitutive equation can be used to take full advantages of the maximum traction provided by the soil and safely improve mining effciency.
文摘AIM: To describe the en bloc perfluorodissection(EBPD) technique and to demonstrate the applicabilityof using preoperative intravitreal bevacizumab duringsmall-gauge vitreoretinal surgery(23-gauge transconjunctival sutureless vitrectomy) in eyes with advancedproliferative diabetic retinopathy(PDR) with tractionalretinal detachment(TRD).METHODS: This is a prospective, interventional caseseries. Participants included 114(eyes) with advancedproliferative diabetic retinopathy and TRD. EBPD wasperformed in 114 eyes(consecutive patients) during23-gauge vitrectomy with the utilization of preoperativebevacizumab(1.25 mg/-0.05 mL). Patients mean age was 45 years(range, 21-85 years). Surgical time had a mean of 55 min(Range, 25-85 min). Mean follow up of this group of patients was 24 mo(range, 12-32 mo). Main outcome measures included best-corrected visual acuity(BCVA), retinal reattachment, and complications.RESULTS: Anatomic success occurred in 100%(114/-114) of eyes. Significant visual improvement [≥ 2 Early Treatment Diabetic Retinopathy Study(ETDRS) lines] was obtained in 69.2%(79/-114), in 26 eyes(22.8%) BCVA remained stable, and in 8 eyes(7%) BCVA decreased(≥ 2 ETDRS lines). Final BCVA was 20/-50 or better in 24% of eyes, between 20/-60 and 20/-400 in 46% of eyes, and worse than 20/-400 in 30% of eyes. Complications included cataract in 32(28%) eyes, iatrogenic retinal breaks in 9(7.8%) eyes, vitreous hemorrhage requiring another procedure in 7(6.1%) eyes, and phthisis bulbi in 1(0.9%) eye.CONCLUSION: This study demonstrates the usefulne-ss of using preoperative intravitreal bevacizumab and EBPD during smallgauge vitreoretinal surgery in eyes with TRD in PDR.
基金Supported by the National Natural Science Foundation of China(No.81870686)Beijing Municipal Natural Science Foundation(No.7184201)Capital’s Funds for Health Improvement and Research(No.2018-1-2021)。
文摘AIM:To investigate the affecting factors of parapapillary gamma and delta zones and other fundus morphological features in high myopia.METHODS:Seventy high myopia patients were included in this retrospective observational study and 47 patients were female.Patients were divided into three groups:no posterior staphyloma(no PS),PS with myopic traction maculopathy(PS with MTM),and PS without MTM using 3-dimensional magnetic resonance imaging and optical coherence tomography.MTM patients were fur ther classified into three types[epiretinal membrane,macular hole,and macular retinoschisis(MRS)].Diameters of the gamma and delta zones were measured among other morphometric variables using fundus photographs.RESULTS:Of the 70 individuals(127 eyes),the mean age was 57.46±13.56y.In univariate analysis,morphological features changed most dramatically in PS with MTM patients,who had the largest gamma zone diameters,the largest disk-fovea distance(DFD)and disk-fovea angle,and the smallest angle kappa and vertical distance of temporal arterial arcade.However,their horizontal delta zone diameter was smaller than in the patients with PS yet without MTM.In multivariate analysis,with axial length(AL)and age adjusted,the horizontal diameter in the delta zone of the PS without MTM group was still significantly larger than in the PS with MTM group(P=0.024).Comparing the three subtypes of MTM patients,the diameters of the gamma zone and DFD in MRS group were the largest.CONCLUSION:The characteristics of the gamma and delta zones change inconsistently in different stages of high myopia.These changes may be associated with anatomical changes caused by local traction.Factors such as PS,AL and age play an important role.These findings may provide a hint about the pathogenesis of traction in high myopia.
基金the National Natural Science Foundation of China,No. 30572411
文摘BACKGROUND:Acupuncture and moxibustion against visceral noxious stimulation present different mechanisms in the peripheral and central nervous systems,involving release of neurotransmitter substance P,acetylcholine esterase,leucine-enkephalin,and c-Fos protein expression.However,there are few reports addressing changes in neurotransmitter expression following manual acupuncture and electroacupuncture against visceral traction pain.OBJECTIVE:To explore changes in neurotransmitter expression in the ileum and protein expression in the medullary visceral zone of visceral traction pain rats undergoing pretreatment of emulational manual acupuncture,and to investigate the differences between emulational manual acupuncture and electroacupuncture.DESIGN,TIME AND SETTING:The randomized,controlled study was performed at the Biomedical Engineering Laboratory,Shanghai University of Traditional Chinese Medicine,Shanghai,China from August 2008 to July 2009.MATERIALS:G6805 electroacupuncture apparatus(Shanghai Medical Electronic Machine Factory,China) and ZSF-I acupuncture manipulation simulation therapeutic system(Chinese Medical Engineering Room,Shanghai University of Traditional Chinese Medicine,Shanghai China) were used in the present study.METHODS:A total of 40 male Sprague Dawley rats were equally and randomly assigned to sham surgery,model,emulational manual acupuncture and electroacupuncture groups.In the emulational manual acupuncture and electroacupuncture groups,emulational manual acupuncture and electroacupuncture were applied at bilateral Zusanli(ST 36) acupoints for 30 minutes,and models of visceral traction pain were established immediately.MAIN OUTCOME MEASURES:Substance P expression,c-Fos and glial fibrillary acidic protein expression were measured using immunohistochemistry.Acetylcholine esterase activity was examined utilizing a colorimetric method.Leucine-enkephalin content was detected using a radioimmune assay.Degree of pain in rats was assessed by pain score.RESULTS:Pain score,substance P expression in the ileum,acetylcholine esterase activity,expression of c-Fos protein and glial fibrillary acidic protein in the medullary visceral zone were significantly decreased following pretreatment of emulational manual acupuncture and electroacupuncture in rats with visceral traction pain(P < 0.05).Compared with the electroacupuncture group,the leucine-enkephalin content was significantly increased,and pain score was significantly diminished in the emulational manual acupuncture group(P < 0.05).CONCLUSION:Emulational manual acupuncture pretreatment decreases acetylcholine esterase activity,increases leucine-enkephalin release,downregulates expression of c-Fos protein and glial fibrillary acidic protein and ultimately inhibits visceral traction pain by reducing substance P release.The effectiveness in inhibiting visceral traction pain is greater when using emulational manual acupuncture compared with electroacupuncture.This is because emulational manual acupuncture effectively increases leucine-enkephalin release.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.52022083,51775453,and 51735012).
文摘The traction motor is the power source of the locomotive.If the surface waviness occurs on the races of the motor bearing,it will cause abnormal vibration and noise,accelerate fatigue and wear,and seriously affect the stability and safety of the traction power transmission.In this paper,an excitation model coupling the time-varying displacement and contact stiffness excitations is adopted to investigate the effect of the surface waviness of the motor bearing on the traction motor under the excitation from the locomotive-track coupled system.The detailed mechanical power transmission path and the internal/external excitations(e.g.,wheel–rail interaction,gear mesh,and internal interactions of the rolling bearing)of the locomotive are comprehensively considered to provide accurate dynamic loads for the traction motor.Effects of the wavenumber and amplitude of the surface waviness on the traction motor and its neighbor components of the locomotive are investigated.The results indicate that controlling the amplitude of the waviness and avoiding the wavenumber being an integer multiple of the number of the rollers are helpful for reducing the abnormal vibration and noise of the traction motor.
