A new thread guide mechanism of a rubbed roving frame is developed, which consists mainly of a plate cam, a linkage and an air bag spring. Characteristics and design parameters of the air spring are explored in this s...A new thread guide mechanism of a rubbed roving frame is developed, which consists mainly of a plate cam, a linkage and an air bag spring. Characteristics and design parameters of the air spring are explored in this study. Based on analyses of winding technology for this kind of package, the kinetic laws of the thread guide is put forward. General design equations of the cam profile are derived, and common kinetic laws of II linkage group which is used for such mechanism design is proposed. It proves theoretically that it is practicable. The experimental results indicate that it can meet the needs of technological demands, and the new thread guide mechanism has been used successfully on textile machines.展开更多
This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears...This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears, and set up approximate formulas for modification coefficients of gears for the first time. And the principles of transmitting rate designing for the system are given. The calculating results demonstrate that the new design method satisfies the demands of processing technology. This mechanism has been used successfully in the kind of rubbed roving frame.展开更多
Liquid crystals (LCs) can be easily oriented by surfaces on a macroscopic scale. Thisphenomenon, known as alignment or anchoring, plays a dominant role in the fabrication ofLC devices. Studying the alignment technique...Liquid crystals (LCs) can be easily oriented by surfaces on a macroscopic scale. Thisphenomenon, known as alignment or anchoring, plays a dominant role in the fabrication ofLC devices. Studying the alignment technique of LCs is of great importance from bothpractical and theoretical points of view. Recently, rubbed polyimide-coated glass substrates have been widely used in LC align-ment. A general belief about the mechanism by which such a polymer alignment methodworks is that alignment acts through the interaction between LC molecules and orientedpolymer chains. This assumption was demonstrated by Barmentlo et al. through surfacesecond-harmonic-generation and optical phase retardation measurements. However, theseoptical techniques can only provide the macroscopic and average information because展开更多
As a common fault of the aero-engine,the blade-casing rubbing(BCR)has the potential to cause catastrophic accidents.In this paper,to investigate the dynamic responses and wear characteristics of the system,the laminat...As a common fault of the aero-engine,the blade-casing rubbing(BCR)has the potential to cause catastrophic accidents.In this paper,to investigate the dynamic responses and wear characteristics of the system,the laminated shell element is used to establish the finite element model(FEM)of a flexibly coated casing system.Using the shell element,the blade is modeled,and the surface stress of the blade is calculated.The stress-solving method of the blade is validated through comparisons with the measured time-domain waveform of the stress.Then,a dynamic model of a blade-flexibly coated casing system with rubbing is proposed,accounting for the time-varying mass and stiffness of the casing caused by coating wear.The effects of the proposed flexible casing model are compared with those of a rigid casing model,and the stress changes induced by rubbing are investigated.The results show that the natural characteristics of the coated casing decrease due to the coating wear.The flexibly coated casing model is found to be more suitable for studying casing vibration.Additionally,the stress changes caused by rubbing are slight,and the change in the stress maximum is approximately 5%under the influence of the abrasive coating.展开更多
This paper focuses on the integration of intangible cultural heritage(ICH)rubbing and students’mental health education,exploring the path of ICH rubbing in improving students’mental health from an innovative perspec...This paper focuses on the integration of intangible cultural heritage(ICH)rubbing and students’mental health education,exploring the path of ICH rubbing in improving students’mental health from an innovative perspective.By elaborating on the theoretical basis of their integration,it constructs an innovative practice model of“cognition-practice-integration-feedback”.Combined with specific practical cases,and with the help of specific data analysis results and charts,it analyzes the effectiveness of this model in alleviating students’stress and anxiety,enhancing self-confidence,and more.It also reflects on the problems in practice and puts forward optimization strategies,providing theoretical and practical references for the innovative integration of ICH inheritance and students’mental health education.展开更多
In addition to blade-to-casing rubbing,drum-to-labyrinth rubbing is another common interaction in aero-engines.In this study,the labyrinth seal is simplified and modeled as an inner ring.First,considering the flexibil...In addition to blade-to-casing rubbing,drum-to-labyrinth rubbing is another common interaction in aero-engines.In this study,the labyrinth seal is simplified and modeled as an inner ring.First,considering the flexibility of both the drum and inner ring,a novel rubbing force model applicable to drum-inner ring rubbing is proposed,and this model is partially validated with the measured vibration responses.Incorporating both drum-inner ring rubbing faults and bolt joint effects,a dynamic model of the shaft-diskdrum-inner ring-vane-casing system(SDDIRVCS)is established with beam-shell hybrid elements to investigate the nonlinear dynamic responses induced by rubbing at various rotational speeds.The established dynamic model of the SDDIRVCS is validated by the comparison of its modal characteristics with those obtained from the ANSYS simulations.The results indicate that the rotor spectrum is dominated by odd-multiple harmonics,while the stator spectrum exhibits prominent even-multiple harmonics.Moreover,the rubbing location between the drum and the inner ring varies with the dynamic behavior of the rotor system.展开更多
It*ss very important to identify the load on rotor bearing system. Based on load identification in time domain, a new method combined with transfer matrix method is applied in rubbing rotor bearing system to estimat...It*ss very important to identify the load on rotor bearing system. Based on load identification in time domain, a new method combined with transfer matrix method is applied in rubbing rotor bearing system to estimate the force on rubbing rotor for the first time. Avoiding calculating the modal parameters, the outside excitation force on multi point and the distribute of internal forces on rubbing rotor bearing system can be identified by this way at the same time. Finally, the simulation is made on partial lateral rubbing rotor bearing system. For the faulty of rotor/stator rub, the point where rubbing occurs and the change of impact forces can be detected by this method in order to improve the accuracy of rotor/stator rub faulty diagnosis.展开更多
In steel squeeze casting process, the working condition of a punch was very rigorous. The abnormal failure models of an H13 punch, such as plastic rubbed damnification, could not be avoided easily. Based on the analys...In steel squeeze casting process, the working condition of a punch was very rigorous. The abnormal failure models of an H13 punch, such as plastic rubbed damnification, could not be avoided easily. Based on the analysis of the flow stress and the friction-shearing stress of an H13 punch in steel squeeze casting process, the following results were obtained： if the flow stress of an H13 punch was smaller than its friction-shearing stress, these abnormal failures could not be avoided; and if there were some protection measures that enable the flow stress to have a greater value than its friction-shearing one, the abnormal failures would not occur. In the production of 45^# steel valves and catenary system components, the flow stress of a lateral H13 punch without any protection measure was about 29 MPa and its friction-shearing stress was about 51 MPa, then, the abnormal failures occurred; however, when the protection measures of the punch enabled its working temperature to have a value below 682 ℃ its flow stress was greater than its friction-shearing stress, and the abnormal failures were avoided.展开更多
According to the background of the rub impact faults of aerial engines and industrial turbines, two kinds of test rigs, on the base of the dynamics model, are established to study the rub impact faults between rotor...According to the background of the rub impact faults of aerial engines and industrial turbines, two kinds of test rigs, on the base of the dynamics model, are established to study the rub impact faults between rotor and stator with free supports. The orbit of the vibration of rotor displacement is respectively examined on the four impact conditions, which are the normal state with no impact, the early sharp impact statement, the semi sharp impact statement and the terminal blunt impact statement. The route to chaos, appearing with the early sharp impact, is observed for the first time. By analyzing the frequency domain characteristics of the experimental data on four impact conditions, it is testified that the appearance of the sub harmonic vibrations of the order 1/3 and 1/4 is the effective evidence to judge whether or not the blade has initial light rub impact. When there are only the harmonic vibrations of the order of 1/1 and 1/2, the blade stator rub impact faults have become very serious.展开更多
Keratoconus is a non-inflammatory disorder which is gradual in development;corneal thinning and ectatic protrusion characterizes it. Keratoconus prevalence varies between different regions depending on several factors...Keratoconus is a non-inflammatory disorder which is gradual in development;corneal thinning and ectatic protrusion characterizes it. Keratoconus prevalence varies between different regions depending on several factors that affecting its prevalence. There are risk factors for developing keratoconus such as demographic and environmental factors. It was suggested that eye rubbing was associated with the development of keratoconus. The main aim of this review was to summarize the literature data about keratoconus and to identify the role of eyerubbing in the aetiology of the disease. A number of 24 articles was reviewed through the Pub Med, Google Scholar and Research Gates. There are many keywords used such as keratoconus, aetiology of keratoconus, eye rubbing, keratoconus prevalence, keratoconus and eye rubbing correlation. We concluded that eye rubbing causes the thinning of keratocyte, and the degree of effect of eye rubbing depends on the period and force of performing eye rubbing. It is recommended to avoid eye rubbing to prevent keratoconus, this can be achieved by avoiding itching and treating dryness of the eye and avoiding wearing eye lenses.展开更多
The effect of La on the performance of a supported RuB amorphous alloy catalyst for benzene selective hydrogenation was studied by means of activity and selectivity tests, such as HRTEM, SAED, XPS, and XRD. The result...The effect of La on the performance of a supported RuB amorphous alloy catalyst for benzene selective hydrogenation was studied by means of activity and selectivity tests, such as HRTEM, SAED, XPS, and XRD. The results show that the addition of La to RuB amorphous alloy catalyst can evidently increase the activity and improve the thermal stability of RuB amorphous alloy to refrain its crystallization. The promoting effect of La on the activity of RuB amorphous alloy catalyst is because of the high dispersion of the active components.展开更多
AIM: To assess the effects of eye rubbing on corneal thickness(CT) and intraocular pressure(IOP)measurements obtained 0-30 min after habitual eye rubbing in symptomatic patients.METHODS: Measurements of IOP and CT wer...AIM: To assess the effects of eye rubbing on corneal thickness(CT) and intraocular pressure(IOP)measurements obtained 0-30 min after habitual eye rubbing in symptomatic patients.METHODS: Measurements of IOP and CT were obtained at five locations(central, temporal, superior,nasal and inferior) before, and every 5min for 30 min interval after 30 s of eye rubbing, for 25 randomly selected eyes of 14 subjects with ocular allergy and 11age-matched normals. Differences in measurements were calculated in each group [Baseline measurements minus measurements recorded at each time interval after eye rubbing(for IOP), and for each corneal location(for CT)]and comparison were then made between groups(allergic versus control) for differences in any observed effects.RESULTS: Within groups, baseline mean IOPs in the allergic patient-group(14.2 ±3.0 mm Hg) and in the control group(13.1±1.9 mm Hg) were similar at all times,after eye rubbing(P 】0.05, for all). The maximum reduction in IOP was 0.8 mm Hg in the control subjects and the maximum increase was also 0.8 mm Hg in the allergic subjects. Between groups(allergic versus control), the changes in IOP remained under 1 mm Hg at all times(P =0.2) after 30 min of eye rubbing. Between 0and 30 min of CT measurements after eye rubbing, the mean central CT(CCT), inferior CT(ICT), superior CT(SCT), temporal CT(TCT) and nasal CT(NCT) did not vary significantly from baseline values in the control and allergic-subject groups(P 】0.05, for both). Between both groups, changes in CT were similar at all locations(P 】0.05)except for the TC which was minimally thinner by about4.4 μm(P =0.001) in the allergic subjects than in the control subjects, 30 min following 30 s of eye rubbing.CONCLUSION: IOP measured in allergic subjects after30 s of habitual eye rubbing was comparable with that obtained in normal subjects at all times between 0 and30 min. Although, CT in the allergic subjects were similar to those of the control subjects at all times, it varied between +10 and-7.5 μm following eye rubbing, with the temporal cornea showing consistent reductions in thickness in the subjects with allergy. However, this reduction was minimal and was considered to not be clinically relevant.展开更多
Considering gyroscopic effects caused by rotational speed,torsional vibration as well as coupling effects among inner rotor,out rotor and casing,a dynamic model of the dual-rotor-casing system is established using fin...Considering gyroscopic effects caused by rotational speed,torsional vibration as well as coupling effects among inner rotor,out rotor and casing,a dynamic model of the dual-rotor-casing system is established using finite element(FE)method.By comparing the natural characteristics obtained from MATLAB and ANSYS,the developed model is verified.Then rubbing-induced vibration responses in dual-rotor-casing system are analyzed.The effects of rotational speed and speed ratio on rubbing vibration responses of the system are discussed.Results show that different combined frequency components will appear in the spectrum except two unbalanced excitation frequencies and their multiple frequency components,and these frequencies can be used as the dual-rotor aero-engine rubbing failure diagnosis frequencies when rubbing occurs.Besides,the amplitude of torsional vibration is larger than that of lateral vibration under the same working condition,and speed ratio has a great impact on the periodicity of the system rubbing-induced motion trajectory.The amplitude of rubbing-induced responses under counter-rotation is less than that under co-rotation with the same parameters.展开更多
文摘A new thread guide mechanism of a rubbed roving frame is developed, which consists mainly of a plate cam, a linkage and an air bag spring. Characteristics and design parameters of the air spring are explored in this study. Based on analyses of winding technology for this kind of package, the kinetic laws of the thread guide is put forward. General design equations of the cam profile are derived, and common kinetic laws of II linkage group which is used for such mechanism design is proposed. It proves theoretically that it is practicable. The experimental results indicate that it can meet the needs of technological demands, and the new thread guide mechanism has been used successfully on textile machines.
文摘This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears, and set up approximate formulas for modification coefficients of gears for the first time. And the principles of transmitting rate designing for the system are given. The calculating results demonstrate that the new design method satisfies the demands of processing technology. This mechanism has been used successfully in the kind of rubbed roving frame.
文摘Liquid crystals (LCs) can be easily oriented by surfaces on a macroscopic scale. Thisphenomenon, known as alignment or anchoring, plays a dominant role in the fabrication ofLC devices. Studying the alignment technique of LCs is of great importance from bothpractical and theoretical points of view. Recently, rubbed polyimide-coated glass substrates have been widely used in LC align-ment. A general belief about the mechanism by which such a polymer alignment methodworks is that alignment acts through the interaction between LC molecules and orientedpolymer chains. This assumption was demonstrated by Barmentlo et al. through surfacesecond-harmonic-generation and optical phase retardation measurements. However, theseoptical techniques can only provide the macroscopic and average information because
基金Project supported by the National Science and Technology Major Project(No.J2022-IV-0005-0022)the Aero Science Foundation of China(No.20230015050001)the Shenyang Science and Technology Plan Project of China(No.24-202-6-01)。
文摘As a common fault of the aero-engine,the blade-casing rubbing(BCR)has the potential to cause catastrophic accidents.In this paper,to investigate the dynamic responses and wear characteristics of the system,the laminated shell element is used to establish the finite element model(FEM)of a flexibly coated casing system.Using the shell element,the blade is modeled,and the surface stress of the blade is calculated.The stress-solving method of the blade is validated through comparisons with the measured time-domain waveform of the stress.Then,a dynamic model of a blade-flexibly coated casing system with rubbing is proposed,accounting for the time-varying mass and stiffness of the casing caused by coating wear.The effects of the proposed flexible casing model are compared with those of a rigid casing model,and the stress changes induced by rubbing are investigated.The results show that the natural characteristics of the coated casing decrease due to the coating wear.The flexibly coated casing model is found to be more suitable for studying casing vibration.Additionally,the stress changes caused by rubbing are slight,and the change in the stress maximum is approximately 5%under the influence of the abrasive coating.
基金2024 Special Research Project on Mental Health Education in Tianjin,“Innovative Research on Intangible Cultural Heritage Inheritance in Promoting Students’Mental Health from the Perspective of Five Education Integration”(Project No.:2024GX18)。
文摘This paper focuses on the integration of intangible cultural heritage(ICH)rubbing and students’mental health education,exploring the path of ICH rubbing in improving students’mental health from an innovative perspective.By elaborating on the theoretical basis of their integration,it constructs an innovative practice model of“cognition-practice-integration-feedback”.Combined with specific practical cases,and with the help of specific data analysis results and charts,it analyzes the effectiveness of this model in alleviating students’stress and anxiety,enhancing self-confidence,and more.It also reflects on the problems in practice and puts forward optimization strategies,providing theoretical and practical references for the innovative integration of ICH inheritance and students’mental health education.
基金supported by the Fundamental Research Funds for the Central Universities(No.N25BSS052)the National Science and Technology Major Project(No.J2022-IV-0005-0022)+2 种基金the Aero Science Foundation of China(No.20230015050001)the Shenyang Science and Technology Plan Project of China(No.24-202-6-01)the Independent Research Project of the National Key Laboratory of Strength and Structural Integrity(No.BYST-QZSYS-24-072-8)。
文摘In addition to blade-to-casing rubbing,drum-to-labyrinth rubbing is another common interaction in aero-engines.In this study,the labyrinth seal is simplified and modeled as an inner ring.First,considering the flexibility of both the drum and inner ring,a novel rubbing force model applicable to drum-inner ring rubbing is proposed,and this model is partially validated with the measured vibration responses.Incorporating both drum-inner ring rubbing faults and bolt joint effects,a dynamic model of the shaft-diskdrum-inner ring-vane-casing system(SDDIRVCS)is established with beam-shell hybrid elements to investigate the nonlinear dynamic responses induced by rubbing at various rotational speeds.The established dynamic model of the SDDIRVCS is validated by the comparison of its modal characteristics with those obtained from the ANSYS simulations.The results indicate that the rotor spectrum is dominated by odd-multiple harmonics,while the stator spectrum exhibits prominent even-multiple harmonics.Moreover,the rubbing location between the drum and the inner ring varies with the dynamic behavior of the rotor system.
文摘It*ss very important to identify the load on rotor bearing system. Based on load identification in time domain, a new method combined with transfer matrix method is applied in rubbing rotor bearing system to estimate the force on rubbing rotor for the first time. Avoiding calculating the modal parameters, the outside excitation force on multi point and the distribute of internal forces on rubbing rotor bearing system can be identified by this way at the same time. Finally, the simulation is made on partial lateral rubbing rotor bearing system. For the faulty of rotor/stator rub, the point where rubbing occurs and the change of impact forces can be detected by this method in order to improve the accuracy of rotor/stator rub faulty diagnosis.
文摘In steel squeeze casting process, the working condition of a punch was very rigorous. The abnormal failure models of an H13 punch, such as plastic rubbed damnification, could not be avoided easily. Based on the analysis of the flow stress and the friction-shearing stress of an H13 punch in steel squeeze casting process, the following results were obtained： if the flow stress of an H13 punch was smaller than its friction-shearing stress, these abnormal failures could not be avoided; and if there were some protection measures that enable the flow stress to have a greater value than its friction-shearing one, the abnormal failures would not occur. In the production of 45^# steel valves and catenary system components, the flow stress of a lateral H13 punch without any protection measure was about 29 MPa and its friction-shearing stress was about 51 MPa, then, the abnormal failures occurred; however, when the protection measures of the punch enabled its working temperature to have a value below 682 ℃ its flow stress was greater than its friction-shearing stress, and the abnormal failures were avoided.
文摘According to the background of the rub impact faults of aerial engines and industrial turbines, two kinds of test rigs, on the base of the dynamics model, are established to study the rub impact faults between rotor and stator with free supports. The orbit of the vibration of rotor displacement is respectively examined on the four impact conditions, which are the normal state with no impact, the early sharp impact statement, the semi sharp impact statement and the terminal blunt impact statement. The route to chaos, appearing with the early sharp impact, is observed for the first time. By analyzing the frequency domain characteristics of the experimental data on four impact conditions, it is testified that the appearance of the sub harmonic vibrations of the order 1/3 and 1/4 is the effective evidence to judge whether or not the blade has initial light rub impact. When there are only the harmonic vibrations of the order of 1/1 and 1/2, the blade stator rub impact faults have become very serious.
文摘Keratoconus is a non-inflammatory disorder which is gradual in development;corneal thinning and ectatic protrusion characterizes it. Keratoconus prevalence varies between different regions depending on several factors that affecting its prevalence. There are risk factors for developing keratoconus such as demographic and environmental factors. It was suggested that eye rubbing was associated with the development of keratoconus. The main aim of this review was to summarize the literature data about keratoconus and to identify the role of eyerubbing in the aetiology of the disease. A number of 24 articles was reviewed through the Pub Med, Google Scholar and Research Gates. There are many keywords used such as keratoconus, aetiology of keratoconus, eye rubbing, keratoconus prevalence, keratoconus and eye rubbing correlation. We concluded that eye rubbing causes the thinning of keratocyte, and the degree of effect of eye rubbing depends on the period and force of performing eye rubbing. It is recommended to avoid eye rubbing to prevent keratoconus, this can be achieved by avoiding itching and treating dryness of the eye and avoiding wearing eye lenses.
文摘The effect of La on the performance of a supported RuB amorphous alloy catalyst for benzene selective hydrogenation was studied by means of activity and selectivity tests, such as HRTEM, SAED, XPS, and XRD. The results show that the addition of La to RuB amorphous alloy catalyst can evidently increase the activity and improve the thermal stability of RuB amorphous alloy to refrain its crystallization. The promoting effect of La on the activity of RuB amorphous alloy catalyst is because of the high dispersion of the active components.
基金Research Centre,College of Applied Medical Sciences and the Deanship of Scientific Research at King Saud University for funding this research
文摘AIM: To assess the effects of eye rubbing on corneal thickness(CT) and intraocular pressure(IOP)measurements obtained 0-30 min after habitual eye rubbing in symptomatic patients.METHODS: Measurements of IOP and CT were obtained at five locations(central, temporal, superior,nasal and inferior) before, and every 5min for 30 min interval after 30 s of eye rubbing, for 25 randomly selected eyes of 14 subjects with ocular allergy and 11age-matched normals. Differences in measurements were calculated in each group [Baseline measurements minus measurements recorded at each time interval after eye rubbing(for IOP), and for each corneal location(for CT)]and comparison were then made between groups(allergic versus control) for differences in any observed effects.RESULTS: Within groups, baseline mean IOPs in the allergic patient-group(14.2 ±3.0 mm Hg) and in the control group(13.1±1.9 mm Hg) were similar at all times,after eye rubbing(P 】0.05, for all). The maximum reduction in IOP was 0.8 mm Hg in the control subjects and the maximum increase was also 0.8 mm Hg in the allergic subjects. Between groups(allergic versus control), the changes in IOP remained under 1 mm Hg at all times(P =0.2) after 30 min of eye rubbing. Between 0and 30 min of CT measurements after eye rubbing, the mean central CT(CCT), inferior CT(ICT), superior CT(SCT), temporal CT(TCT) and nasal CT(NCT) did not vary significantly from baseline values in the control and allergic-subject groups(P 】0.05, for both). Between both groups, changes in CT were similar at all locations(P 】0.05)except for the TC which was minimally thinner by about4.4 μm(P =0.001) in the allergic subjects than in the control subjects, 30 min following 30 s of eye rubbing.CONCLUSION: IOP measured in allergic subjects after30 s of habitual eye rubbing was comparable with that obtained in normal subjects at all times between 0 and30 min. Although, CT in the allergic subjects were similar to those of the control subjects at all times, it varied between +10 and-7.5 μm following eye rubbing, with the temporal cornea showing consistent reductions in thickness in the subjects with allergy. However, this reduction was minimal and was considered to not be clinically relevant.
基金supported by the National Natural Science Foundation of China(No.11772089)the Fundamental Research Funds for the Central Universities (Nos. N160312001and N160313004)the Research Project of State Key Laboratory of Mechanical System and Vibration(No.MSV201707)
文摘Considering gyroscopic effects caused by rotational speed,torsional vibration as well as coupling effects among inner rotor,out rotor and casing,a dynamic model of the dual-rotor-casing system is established using finite element(FE)method.By comparing the natural characteristics obtained from MATLAB and ANSYS,the developed model is verified.Then rubbing-induced vibration responses in dual-rotor-casing system are analyzed.The effects of rotational speed and speed ratio on rubbing vibration responses of the system are discussed.Results show that different combined frequency components will appear in the spectrum except two unbalanced excitation frequencies and their multiple frequency components,and these frequencies can be used as the dual-rotor aero-engine rubbing failure diagnosis frequencies when rubbing occurs.Besides,the amplitude of torsional vibration is larger than that of lateral vibration under the same working condition,and speed ratio has a great impact on the periodicity of the system rubbing-induced motion trajectory.The amplitude of rubbing-induced responses under counter-rotation is less than that under co-rotation with the same parameters.
