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Mechanism of cross-level settlements and void accumulation of wide and conventional sleepers in railway ballast
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作者 Olga Nabochenko Mykola Sysyn +1 位作者 Norman Krumnow Szabolcs Fischer 《Railway Engineering Science》 EI 2024年第3期361-383,共23页
The cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses.However,the mechanism of the irregul... The cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses.However,the mechanism of the irregularities initiation and development is unclear.The motivation of the present study was the previous experimental studies on the application of wide sleepers in the ballasted track.The long-term track geometry measurements with wide sleepers show an enormous reduction of the vertical longitudinal irregularities compared to the conventional track.However,wide sleepers had higher twist and cross-section level irregularities.The present paper aims to explain the phenomenon by discrete element method(DEM)modeling the development process of sleeper inhomogeneous support at cross-level depending on the sleeper form.The DEM simulations show that the maximal settlement intensity is up to 3.5 times lower for a wide sleeper in comparison with the conventional one.Nevertheless,the cross-level differential settlements are almost the same for both sleepers.The particle loading distribution after all loading cycles is concentrated on the smaller area,up to the half sleeper length,with fully unloaded zones under sleeper ends.Ballast flow limitation under the central part of the sleeper could improve the resilience of wide sleepers to the development of cross-level irregularities.The mechanism of initiation of the cross-level irregularity is proposed,which assumes the loss of sleeper support under sleeper ends.The further growth of inhomogeneous settlements along the sleeper is assumed as a result of the interaction of two processes:ballast flow due to dynamic impact during void closing and on the other side high pressure due to the concentration of the pressure under the middle part of the sleeper.The DEM simulation results support the assumption of the mechanism and agree with the experimental studies. 展开更多
关键词 Wide sleeper Ballasted track Sleeper support inhomogeneity Sleeper foot form Discrete element modeling Void accumulation
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Influence of unsupported sleepers on the dynamic stability of ballasted bed based on wheelset impact tests 被引量:1
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作者 Juzhen Liu Shuai Du +4 位作者 Ganzhong Liu Ping Wang Rong Chen Xiankui Wei Hao Liu 《Railway Engineering Science》 2023年第1期52-60,共9页
The unsupported sleeper can change the load characteristics of ballast particles and thus affect the dynamic stability of a ballasted bed.In this work,a laboratory test was constructed on a ballasted track containing ... The unsupported sleeper can change the load characteristics of ballast particles and thus affect the dynamic stability of a ballasted bed.In this work,a laboratory test was constructed on a ballasted track containing unsupported sleepers.The ballasted track was excited by a wheelset,and the influence of unsupported sleepers on the dynamic stability of a ballasted bed was studied.The results show that the main frequency of the sleeper vibration appeared at 670 Hz,and the first-order rigid vibration mode at the frequency of 101 Hz had a significant effect on the condition without the unsupported sleeper.When the sleepers were continuously unsupported,the vibration damping effect of ballasted bed within the frequency range of 0–450 Hz was better than that at higher frequencies.Within the frequency range of 70–250 Hz,the vibration damping effect of the ballasted bed with unsupported sleepers was better than that without the unsupported sleeper.Owing to the excitation from the wheelset impact,the lateral resistance of the ballasted bed with unsupported sleepers whose hanging heights were 30,60,and 90 mm increased by 37.43%,12.25%,and 18.23%,respectively,while the lateral resistance of the ballasted bed without the unsupported sleeper remained basically unchanged.The unsupported sleeper could increase the difference in the quality of the ballasted bed between two adjacent sleepers.In addition,test results show that the hanging height of the unsupported sleeper had little effect on the lateral resistance of a ballasted bed without external excitation,but had an obvious effect on the rate of change of the lateral resistance of a ballasted bed and the acceleration amplitude of the sleeper vibration under the wheelset impact. 展开更多
关键词 Unsupported sleeper Ballasted bed Wheelset impact test VIBRATION Dynamic stability
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Stability issues of the continuous welded rail track on the concrete sleepers on the curves with radius R ≤ 300 m
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作者 Victor Vasylevich Rybkin Nicolai Petrovich Nastechik 《Research in Cold and Arid Regions》 CSCD 2013年第5期654-658,共5页
This paper describes the economic and technological benefits of installing continuous welded rail (CWR) track on sharp (radius≤300 m) railway curves. A new form of prestressed concrete sleepers developed by the V... This paper describes the economic and technological benefits of installing continuous welded rail (CWR) track on sharp (radius≤300 m) railway curves. A new form of prestressed concrete sleepers developed by the V. Lazaryan Dniprope- trovsk National University of Railway Transport is shown to improve the lateral shift resistance of CWR track in sharp curves and the use of anchor sleepers on tangents is shown to make it possible to lower the fastening temperature of the CWR track in order to increase the rail lifespan. 展开更多
关键词 continuous welded rail (CWR) track track configuration STABILITY sharp curves anchor sleepers
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Application of International Standards in the Design of Monoblock Contrete Sleepers for Argentinian Railways
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作者 Scassera Melina Roberto S.Carnicer 《Journal of Civil Engineering and Architecture》 2020年第9期509-515,共7页
It is presented a State of the Art of international standards in the field of monoblock concrete sleepers design and calculation.Taking into account the fact that the Argentinian broad track gauge(1,676 mm)is differen... It is presented a State of the Art of international standards in the field of monoblock concrete sleepers design and calculation.Taking into account the fact that the Argentinian broad track gauge(1,676 mm)is different to international track gauge(1,435 mm)that is worldwide used,a comparative analysis is developed in order to evaluate the performance of internationals standards in the design of the sleepers used in Argentinian railways.Recommendations for future research are provided. 展开更多
关键词 concrete sleeper international standards bending moments
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Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiberreinforced concrete railway sleepers
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作者 Sayed AHMED Hossam ATEF Mohamed HUSAIN 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2023年第3期411-428,共18页
In this study,ultrahigh-performance fiber-reinforced concrete(UHPFRC)used in a type B70 concrete sleeper is investigated experimentally and parametrically.The main parameters investigated are the steel fiber volume fr... In this study,ultrahigh-performance fiber-reinforced concrete(UHPFRC)used in a type B70 concrete sleeper is investigated experimentally and parametrically.The main parameters investigated are the steel fiber volume fractions(0%,0.5%,1%,and 1.5%).Under European standards,35 UHPFRC sleepers are subjected to static bending tests at the center and rail seat sections,and the screw on the fastening system is pulled out.The first cracking load,failure load,failure mode,crack propagation,load–deflection curve,load–crack width,and failure load from these tests are measured and compared with those of a control sleeper manufactured using normal concrete C50.The accuracy of the parametric study is verified experimentally.Subsequently,the results of the study are applied to UHPFRC sleepers with different concrete volumes to investigate the effects of the properties of UHPFRC on their performance.Experimental and parametric study results show that the behavior of UHPFRC sleepers improves significantly when the amount of steel fiber in the mix is increased.Sleepers manufactured using UHPFRC with a steel fiber volume fraction of 1%and a concrete volume less than 25%that of standard sleeper B70 can be used under the same loads and requirements,which contributes positively to the cost and surrounding environment. 展开更多
关键词 pre-stressed concrete sleeper ultrahigh performance fiber-reinforced concrete pull-out test static bending test steel fiber aspect ratio volume fraction
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Analysis of mesoscopic mechanical dynamic characteristics of ballast bed with under sleeper pads 被引量:1
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作者 Xiong Yang Liuyang Yu +3 位作者 Xuejun Wang Zhigang Xu Yu Deng Houxu Li 《Railway Engineering Science》 EI 2024年第1期107-123,共17页
The meso-dynamical behaviour of a high-speed rail ballast bed with under sleeper pads(USPs)was studied.The geometrically irregular refined discrete element model of the ballast particles was constructed using 3D scann... The meso-dynamical behaviour of a high-speed rail ballast bed with under sleeper pads(USPs)was studied.The geometrically irregular refined discrete element model of the ballast particles was constructed using 3D scanning techniques,and the 3D dynamic model of the rail-sleeper-ballast bed was constructed using the coupled discrete element method-multiflexible-body dynamics(DEM-MFBD)approach.We analyse the meso-mechanical dynamics of the ballast bed with USPs under dynamic load on a train and verify the correctness of the model in laboratory tests.It is shown that the deformation of the USPs increases the contact area between the sleeper and the ballast particles,and subsequently the number of contacts between them.As the depth of the granular ballast bed increases,the contact area becomes larger,and the contact force between the ballast particles gradually decreases.Under the action of the elastic USPs,the contact forces between ballast particles are reduced and the overall vibration level of the ballast bed can be reduced.The settlement of the granular ballast bed occurs mainly at the shallow position of the sleeper bottom,and the installation of the elastic USPs can be effective in reducing the stress on the ballast particles and the settlement of the ballast bed. 展开更多
关键词 Under sleeper pads Ballast bed Discrete element method Mesoscopic mechanical dynamic characteristics
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Numerical Study on Lateral Buckling Mode of Pipelines Laid on A Sleeper
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作者 LIU Run HAO Xin-tong +2 位作者 LI Cheng-feng YU Zheng LI Qing-xin 《China Ocean Engineering》 SCIE EI CSCD 2023年第3期495-505,共11页
Because non-buried submarine pipelines under cyclic thermal loading are prone to global buckling,sleepers are commonly laid along the pipeline route to induce a series of relatively small and controllable lateral buck... Because non-buried submarine pipelines under cyclic thermal loading are prone to global buckling,sleepers are commonly laid along the pipeline route to induce a series of relatively small and controllable lateral buckling.A finite element model which can simulate the transformation of pipeline laid on a sleeper from vertical buckling to lateral buckling is established in this work.The parameters of sleeper affecting pipeline buckling modes are analysed,and a new kind of sleeper is proposed aimed at avoiding antisymmetric buckling.Results show that the lateral trigger force can avoid antisymmetric lateral buckling when acting between 1℃and 13℃before the critical buckling temperature.The range increases slightly with increasing trigger force.Compared with an ordinary sleeper,the proposed new sleeper with slider can reduce the critical buckling temperature by 25%,which significantly improves the success rate of sleepers. 展开更多
关键词 submarine pipeline buckling mode initial imperfection new sleeper
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Feasibility and acceptability of wrist actigraph in assessing sleep quality and sleep quantity: A home-based pilot study in healthy volunteers 被引量:1
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作者 Zaswiza Mohamad Noor Alesha J. Smith +1 位作者 Simon S. Smith Lisa M. Nissen 《Health》 2013年第8期63-72,共10页
Purpose: This study aimed to determine the feasibility and acceptability of actigraphy to monitor sleep quality and quantity in healthy self-rated good sleeper adults at home-based settings. Method: Sixteen healthy vo... Purpose: This study aimed to determine the feasibility and acceptability of actigraphy to monitor sleep quality and quantity in healthy self-rated good sleeper adults at home-based settings. Method: Sixteen healthy volunteers (age > 18) were invited to participate. Each participant was provided with a wrist actigraph device to be worn for 24-hour/day for seven consecutive days to monitor their sleep-wake patterns. Actigraphy data were downloaded using-proprietary software to generate an individual-sleep report. Participants also completed a set of self-reported Health Related Quality of Life (HRQOL) using WHO (five) Well Being Index (WBI) questionnaires. Results: Actigraphy was well accepted by all participants. Only 43.8% of the participants achieved normal total sleep time (TST) and 62.5% had a mean sleep efficiency value below the normal range. Despite a reduced quality of sleep among the participants, the self-reported HRQOL scores produced by the WHO-5 WBI showed a “fair” to “good” among the participants. Conclusions: To maintain healthy well-being, it is vital to have efficient and quality sleep. Insufficient and poor sleep may contribute to various health problems and hazardous outcomes. People often believe they have normal and efficient sleep, not realising they may be developing poor sleep habits. This study found that actigraphy can be easily utilized to monitor sleep-wake patterns at home-based settings. We proposed that actigraphy could be adapted for use in the primary care settings (e.g. community pharmacy) to improve the sleep health management in the community. 展开更多
关键词 ACTIGRAPHY SLEEP Quality SLEEP Quantity HOME-BASED Good sleepers
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Sleep Posture Affects Sleep Parameters Differently in Young and Senior Japanese as Assessed by Actigraphy
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作者 Akiko Nojiri Chikako Okumura Yushi Ito 《Health》 2014年第21期2934-2944,共11页
In an attempt to study the relationship between sleep postures and sleep parameters assessed by actigraphy, we applied the newly developed Activity Monitoring and Evaluation System (A-MES) and actigraphy at the same t... In an attempt to study the relationship between sleep postures and sleep parameters assessed by actigraphy, we applied the newly developed Activity Monitoring and Evaluation System (A-MES) and actigraphy at the same time to younger and senior Japanese volunteer groups. It was found that sleep postures and diurnal activity determines, to some extent, sleep parameters including activity mean score (AMS), activity index (ACTX), waking episodes (WEP) and sleep fragmentation index (SFX). It was also found that sleep properties are different in younger and senior Japanese. For example, increase in the proportion of time in the supine position resulted in enhancement and deterioration of the sleep in the younger and senior groups, respectively. Furthermore, there were correlations between supine posture and AMS, ACTX, SFX, total minutes scored as awake (TMSA) and WEP obtained by actigraphy in the younger group, but only AMS and ACTX in senior group. In addition, we also assessed sleep parameters by use of questionnaires, and found that objective sleep quality was rather poor but subjective sleep quality was better in the senior group. In the younger group, in contrast, objective sleep quality was better but subjective sleep quality was poor. On the other hand, there was no correlation between sleep parameters assessed by actigraphy and self-report at all. The present study with A-MES and actigraphy provides the first evidence that sleep posture affects sleep quality and is a convenient, inexpensive and home-based method for studying sleep. 展开更多
关键词 ACTIGRAPHY Activity Monitoring and Evaluation System (A-MES) SLEEP POSTURE SLEEP Quality Good sleepers
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EFFECT OF DISCRETE SUPPORTS OF RAIL ON INITIATION AND EVOLUTION OF RAIL CORRUGATION 被引量:8
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作者 JinXuesong WangKaiyun WenZefeng ZhangWeihua 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2005年第1期37-41,共5页
The effect of discrete support of rail on the formation and evolution of railcorrugation is primarily investigated with numerical method in the situation of wheelset curvingsteadily and repeatedly. In the numerical an... The effect of discrete support of rail on the formation and evolution of railcorrugation is primarily investigated with numerical method in the situation of wheelset curvingsteadily and repeatedly. In the numerical analysis of corrugation it is considered that acombination of Kalker's rolling contact theory with non-Hertzian to be modified, a linear frictionalwork model and a vertical dynamics model of railway vehicle coupled with a curved track. And theuneven support stiffness of rail in the vertical direction due to discrete sleeper support and thedifferent running speed of the wheelset are taken into consideration. The damage on the runningsurface of rail, concerning rail corrugation formation, is restricted to wear mechanism of railmaterial. The numerical results obtained indicate that the discrete supports of rail by sleepershave a great influence on the formation of the corrugation under the condition of non-zero andstable creepages of wheelset and track. 展开更多
关键词 Rail corrugation Sleeper bay Vibration Rolling contact Frictional work Dynamics
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Discrete element method of improved performance of railway ballast bed using elastic sleeper 被引量:8
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作者 高亮 罗奇 +2 位作者 徐旸 井国庆 蒋函珂 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第8期3223-3231,共9页
With the development of high-speed and heavy-haul railway in China, problems like insufficient thickness of ballast bed and overlarge track stiffness are obvious. Ballast may break into small particles and their conta... With the development of high-speed and heavy-haul railway in China, problems like insufficient thickness of ballast bed and overlarge track stiffness are obvious. Ballast may break into small particles and their contact status will deteriorate under cyclic loading, resulting in ballast degradation. Discrete element method(DEM) was used to research improved performance of ballast bed using elastic sleeper. Clusters were generated by bonding spheres to model real ballasts, while broken bonds were utilized to distinguish breakage. Two kinds of ballast beds with elastic sleeper and conventional sleeper were established, respectively. After applying cyclic loading to the models, differences of mechanical properties between two models were analyzed by contrasting their dynamic behavior indexes, such as particle contact force, sleeper settlement, vibration velocity and acceleration, breakage characteristic. The results illustrate that compared with conventional sleeper, elastic sleeper increases sleeper settlement, while reduces ballast vibration and contact force between particles, which could depress ballast breakage. 展开更多
关键词 railway ballast bed discrete element method elastic sleeper BREAKAGE mechanical property
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Discrete element method analysis of lateral resistance of fouled ballast bed 被引量:3
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作者 XU Yang 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第9期2373-2381,共9页
The lateral resistance of sleeper plays an important role in ensuring the stability of a railway track, which may change in the operation of railway, due to the fouling in the ballast bed. In this work, discrete eleme... The lateral resistance of sleeper plays an important role in ensuring the stability of a railway track, which may change in the operation of railway, due to the fouling in the ballast bed. In this work, discrete element method was adopted to investigate the effect of fouling on the lateral resistance of sleeper. The shape information of ballast was captured by method of three-dimensional vision reconstruction. In order to calibrate the mechanical parameters and verify the models, a lateral resistance field test was carried out by using a custom-made device. The contact force distributions in the different parts of sleeper as well as the interaction between ballast and sleeper were discussed in depth. The results show that fouling of ballast bed evidently reduces the lateral resistance of sleeper and the decreasing degree is also related to the fouled position of ballast bed, in the order of shoulder > bottom > side.Therefore, the effect of fouling, especially the fouling in the ballast shoulder, on the lateral resistance of sleeper, should be taken into account in ballast track maintenance work. 展开更多
关键词 discrete element modelling three-dimensional vision reconstruction BALLAST lateral resistance of sleeper ballast fouling
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Rates of oxygen consumption and tolerance of hypoxia and desiccation in Chinese black sleeper(Bostrichthys sinensis)and mudskipper(Boleophthalmus pectinirostris)embryos 被引量:3
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作者 CHEN Shixi HONG Wanshu +2 位作者 ZHANG Qiyong WU Renxie WANG Qiong 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2006年第4期91-98,共8页
The rates of oxygen consumption, tolerance of hypoxia and desiccation of the Chinese black sleeper ( Bostrichthys sinensis) and mudskipper (Boleophthalmus pectinirostris) embryos were investigated. The pattern of ... The rates of oxygen consumption, tolerance of hypoxia and desiccation of the Chinese black sleeper ( Bostrichthys sinensis) and mudskipper (Boleophthalmus pectinirostris) embryos were investigated. The pattern of oxygen consumption of the Chinese black sleeper embryos was similar to that of the mudskipper ones. The lowest rates of oxygen consumption [ ( 1.65 ±0. 66) nmol/ (ind. ·h) ] of the Chinese black sleeper embryos 16 h after fertilization and the lowest rates of oxygen consumption [ (0.79± 0.08 )nmolf( ind. · h) ] of the mudskipper embryos 6 h after fertilization were recorded, respectively. Then the rates of oxygen consumption of these two species embryos increased gradually until hatching [ (8.26 ± 1.70 ) nmolf( ind.· h) in the Chinese black sleeper, (2.69 ± 0.23 )nmolf( ind. · h) in mudskipper]. After exposure to hypoxia water (0.16 mg/dm^3), bradycardia of the embryos occurred in both the Chinese black sleeper and the mudskipper. However, the Chinese black sleeper embryos survived approximately 45 min longer than the mudskipper ones. After exposure to desiccation at a relative humidity of 58%, bradycardia of the embryos was observed in both the Chinese black sleeper and the mudskipper, and the Chinese black sleeper embryos lived approximately 9 min longer than the mudskipper ones. 展开更多
关键词 Chinese black sleeper (Bostrichthys sinensis) mudskipper (Boleophthalmus pectinirostris) EMBRYO oxygen consumption rate hypoxia tolerance desiccation tolerance
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Experimental investigation of the dynamic behavior of railway track with sleeper voids 被引量:3
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作者 Mykola Sysyn Olga Nabochenko Vitalii Kovalchuk 《Railway Engineering Science》 2020年第3期290-304,共15页
The deterioration of the sleeper support on the ballasted track begins with the accumulation of sleeper voids.The increased dynamic loading in the voided zone and the ballast contact conditions cause the accelerated g... The deterioration of the sleeper support on the ballasted track begins with the accumulation of sleeper voids.The increased dynamic loading in the voided zone and the ballast contact conditions cause the accelerated growth of the settlements in the voided zones,which results in the appearance of local instabilities like ballast breakdown,white spots,subgrade defects,etc.The recent detection and quantification of the sleeper voids with track-side and onboard monitoring can help to avoid or delay the development of local instabilities.The present paper is devoted to the study of the dynamic behavior of railway track with sleeper voids in the ballast breakdown zone.The result of the experimental track-side measurements of rail acceleration and deflection is presented.The analysis shows the existence of the dynamic impact during wheel entry in the voided zone.However,the measured dynamic impact is subjected to the bias of the track-side measurement method.Both the mechanism of the impact and the measurement aspects are explained by using the one-beam model on viscoelastic foundation.The void features in the dynamic behavior are analyzed for the purpose of track-side and onboard monitoring.A practical method of the void parameter quantification is proposed. 展开更多
关键词 Ballasted track Sleeper voids Ballast breakdown Track-side measurement Rail deflection Dynamic modeling Impact Identification
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Production of functional sperm from in vitro-cultured premeiotic spermatogonia in a marine fish 被引量:1
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作者 Hong Zhang Wan-Wan Zhang +4 位作者 Cheng-Yu Mo Meng-Dan Dong Kun-Tong Jia Wei Liu Mei-Sheng Yi 《Zoological Research》 SCIE CAS CSCD 2022年第4期537-551,共15页
In vitro production of functional gametes can revolutionize reproduction by reducing generation intervals and accelerating genetic breeding in aquaculture,especially in fish with relatively long generations.Neverthele... In vitro production of functional gametes can revolutionize reproduction by reducing generation intervals and accelerating genetic breeding in aquaculture,especially in fish with relatively long generations.Nevertheless,functional sperm production from in vitro-cultured spermatogonia remains a challenge in most aquaculture fish.In this study,we isolated and characterized premeiotic spermatogonia from marine four-eyed sleepers(Bostrychus sinensis),which are prone to ovotesticular or sterile testicular development,and induced the differentiation of the spermatogonia into flagellated sperm in a three-dimensional(3D)culture system.Artificial insemination indicated that the in vitro-derived sperm were capable of fertilizing mature oocytes to develop into normal larvae.Furthermore,melatonin significantly promoted spermatogonia proliferation and differentiation through the ERK1/2 signaling pathway,and thus increased the efficiency in functional sperm production.The 3D culture system and resulting functional sperm hold great promise for improving the genetic breeding of aquaculture fish. 展开更多
关键词 In vitro spermatogenesis 3D culture model SPERMATOGONIA Four-eyed sleeper MELATONIN Genetic breeding
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MODIFICATION THE CEMENTIOUS MATERIAL OF ULTRA-HIGH-STRENGTH SLEEPER CONCRETE
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作者 崔崇 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2000年第2期28-34,共7页
This paper presents investigation results on the natural ultra-fine mineral flour of crystalline silica fume (CSF) and porous quartz sand stone (PQSS) which can modify cement mortar strength under hydrothermal synthe... This paper presents investigation results on the natural ultra-fine mineral flour of crystalline silica fume (CSF) and porous quartz sand stone (PQSS) which can modify cement mortar strength under hydrothermal synthesis reaction (HSR) in the autoclave-cured condition. The replacement of cement by CSF and PQSS can signifi cantly increase the Jflerural and compressive strength which reach 22MPa and 150MPa respectively and de-crease the porosity oj the cement mortar. The ratio oj fine aggregation, standard sand to cementions material has sig nificant influence on the mortar strength. The mechanisms involved in cement and natural mineral flour and the HSR are presented. CaO/SiO2 ratio ranges from 3. 20 to 1. 11. the main hydrate phase is C2SH and there is not Tober-morite through X-Ray diffraction qualitative analysis. The new and ultra-high strength cementious material as basic material of sleeper concrete can he used in prestressed reinforcement sleeper concrete. 展开更多
关键词 crystalline silica furne ultra-fine natural mineral flour sleeper concrete ultra high strength cementious material
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Dynamic Response of Elastic Sleeper Ballasted Track on Bridge
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作者 翟淼 王平 +1 位作者 李培刚 陈小平 《Journal of Southwest Jiaotong University(English Edition)》 2010年第2期124-128,共5页
A vehicle-track-bridge coupling dynamics model was built based on the theory of vehicle-track coupling dynamics. Using this model, a comparison was made between the dynamic response of an elastic sleeper ballasted tra... A vehicle-track-bridge coupling dynamics model was built based on the theory of vehicle-track coupling dynamics. Using this model, a comparison was made between the dynamic response of an elastic sleeper ballasted track and a common sleeper ballasted track on bridge under the same working conditions. The results show that laying elastic sleepers on the bridge could solve the problem of large track stiffness caused by a thin ballast thickness, and improve the dynamic response of the bridge. This is beneficial to train operation safety and riding comfort. 展开更多
关键词 Elastic sleeper Ballasted track Coupling dynamics Dynamic response BRIDGE
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无声叫醒服务——Light Sleeper寝饰
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《新潮电子》 2004年第5期133-133,共1页
关键词 LIGHT SLEEPER 寝饰 无声叫醒服务 功能
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新型冷冻载体Cell Sleeper在微量人精子冷冻中的应用 被引量:6
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作者 邹宇洁 杨菁 +3 位作者 尹太郎 徐望明 吴庚香 张怡 《武汉大学学报(医学版)》 CAS 北大核心 2013年第2期205-208,共4页
目的:评价一种新型的冷冻载体cell sleeper用于微量人类精子的冷冻效果。方法:将60例患者的精液标本液化,PureSperm梯度离心处理后进行两部分实验。第一部分运用cell sleeper在不同液量(0.5μl,1μl和2μl)含有冷冻保护剂的液滴进行精... 目的:评价一种新型的冷冻载体cell sleeper用于微量人类精子的冷冻效果。方法:将60例患者的精液标本液化,PureSperm梯度离心处理后进行两部分实验。第一部分运用cell sleeper在不同液量(0.5μl,1μl和2μl)含有冷冻保护剂的液滴进行精子冷冻,液氮中冷冻2周,比较冻融前后各组精子存活率和活力,以找到cellsleeper用于微量精子冷冻的最佳液量条件。在第一部分实验摸索的液量条件下,进行第二部分cell sleeper中进行单精子冷冻,并与常规冻存管进行比较。结果:第一部分实验中,三组精子解冻后的活力和存活率均较冷冻前下降,但三组间解冻后精子存活率和活力比较无差异。第二部分实验中,cell sleeper组精子解冻后的回收率和存活率明显高于常规冻存管组。结论:cell sleeper是一种理想的微量精子冷冻载体,解冻后可保证较高的精子回收率和存活率。 展开更多
关键词 微量精子 冷冻保存 CELL SLEEPER 回收率
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The molecular mechanism of natural short sleep:A path towards understanding why we need to sleep 被引量:1
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作者 Liubin Zheng Luoying Zhang 《Brain Science Advances》 2022年第3期165-172,共8页
Sleep constitutes a third of human life and it is increasingly recognized as important for health.Over the past several decades,numerous genes have been identified to be involved in sleep regulation in animal models,b... Sleep constitutes a third of human life and it is increasingly recognized as important for health.Over the past several decades,numerous genes have been identified to be involved in sleep regulation in animal models,but most of these genes when disturbed impair not only sleep but also health and physiological functions.Human natural short sleepers are individuals with lifelong short sleep and no obvious adverse outcomes associated with the lack of sleep.These traits appear to be heritable,and thus characterization of the genetic basis of natural short sleep provides an opportunity to study not only the genetic mechanism of human sleep but also the relationship between sleep and physiological function.This review focuses on the current understanding of mutations associated with the natural short sleep trait and the mechanisms by which they contribute to this trait. 展开更多
关键词 SLEEP DURATION NATURAL SHORT SLEEP SHORT SLEEPER gene mutation
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