Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the b...Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.展开更多
The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and...The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and beyond.Herein,by learning from the pencil-writing process,a facile solid-ink rubbing technology(SIR-tech)is invented to address the above challenge.The solid-ink is exampled by rational combination of liquid metal and graphite particles.By harnessing the synergistic effects between rubbing and adhesion,controllable metallic skin is successfully formed onto metals,woods,ceramics,and plastics without limitation in size and shape.Moreover,outperforming pure liquid-metal coating,the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing.The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well.For applications,the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils.Meanwhile,advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from-196 to 120℃.This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.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
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
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
The nonlinear dynamic behavior of a rubbing rotor system was studied with a mathematical model established with the eccentricity and interaction between bending and torsional vibrations taken into consideration. The n...The nonlinear dynamic behavior of a rubbing rotor system was studied with a mathematical model established with the eccentricity and interaction between bending and torsional vibrations taken into consideration. The nonlinear vibrational response of a rubbing rotor was analyzed using numerical integral, spectroscopic analysis and Poince mapping method, which made it possible to have better understanding of the vibrational characteristics of partial rubbing and complete circular rubbing rotors. The numerical results reveal the response of torsional vibration mainly takes a form of superchronous motion, and its frequency decreases as the rotational speed increases when partial rubbing occurs, and the response of torsional vibration is synchronous when complete circular rubbing occurs. The comparison of the dynamics of rubbing rotors with and without the interaction between bending and torsional vibrations shows the interaction between bending and torsional vibrations advances the rotational speed, at which the response of bending vibration changes from a synchronous motion into a quasi periodic motion, and the interaction between bending and torsional vibrations reduces stability of the rubbing rotor.展开更多
Because of the effect of unbalance excitation and nonlinear magnetic force, the large vibration of the rotor supported by active magnetic bearing(AMB) will go beyond the radial gap of the bearing, even causing mecha...Because of the effect of unbalance excitation and nonlinear magnetic force, the large vibration of the rotor supported by active magnetic bearing(AMB) will go beyond the radial gap of the bearing, even causing mechanical touch-rubbing when the system works at an operational speed closer to the critical speed. In order to investigate this problem, the linear model and nonlinear model of the single mass symmetric rigid rotor system supported by AMB are established respectively and the corresponding transfer functions of close-loop system are given. To pass through the numerical calculation by using MATLAB/Simulink, the effect of both the unbalance response and threshold speed of touch-rubbing of the system subjected to nonlinear magnetic forces and nonlinear output current of power amplifier are studied. Furthermore, threshold speed of touch-rubbing of the rotor-bearing system is defined and the results of numerical simulation are presented. Finally, based on above studies, two methods of increasing the touch-rubbing threshold speed are discussed.展开更多
Considering the elastic supports,the finite element model of rotor-bladed disk-casing system is established using commercial software ANSYS/LS-DYNA.Assuming that broken blade is released from the disk,the complicate r...Considering the elastic supports,the finite element model of rotor-bladed disk-casing system is established using commercial software ANSYS/LS-DYNA.Assuming that broken blade is released from the disk,the complicate rubbing responses of unbalanced rotor-bladed disk-casing system are studied under different operational speeds.In addition,influences of both plastic deformation of blade and casing failure are analyzed.The results show that there exist some multiple even fractional frequencies in the transient and steady vibration responses of unbalanced rotor.Besides,one nodal diameter vibration of bladed disk coupling with the lateral vibration of the shaft as well as the first order bending vibration of blade can be excited under low operational speed,while the first order bending vibration of blade coupling with the lateral vibration of disk-shaft is easily excited under high operational speed.During rubbing process,three distinct contact states can be observed:broken blade-casing contact,broken blade-blade component-casing contact and broken blade-casing contact/blade component-casing contact/blade selfcontact.It is worth noting that the third contact state is related to the operational speed.With the increase of operational speed,self-contact in the blade may occur.展开更多
The phase characteristic of a disk rubbing with a ring supported elastically is investigated and used to explain the mechanism of stiffness increase phenomenon. As long as the rubbing is maintained, the averaged phase...The phase characteristic of a disk rubbing with a ring supported elastically is investigated and used to explain the mechanism of stiffness increase phenomenon. As long as the rubbing is maintained, the averaged phase difference between the disk and the rotating mass on the disk is defi- nitely less than π/2. When the rubbing finishes, the phase difference quickly approaches to 7r. This behavior is inde- pendent of the physics parameters of the rubbing system. The theoretical results are qualitatively verified with experiments.展开更多
Polyurethane modified organic silicone was successfully prepared from hydroxyl-terminated polyether modified silicone,toluene-2,4-diisocyanate( TDI), and NaHSO3. The chemical structure of the polyurethane modified org...Polyurethane modified organic silicone was successfully prepared from hydroxyl-terminated polyether modified silicone,toluene-2,4-diisocyanate( TDI), and NaHSO3. The chemical structure of the polyurethane modified organic silicone was characterized by FT-IR and1H-NMR. The polymer film on the cotton surface was investigated by scanning electron microscopy( SEM) and the results showed that a thin polymer film was successfully formed. The FT-IR of treated cotton fabrics indicated that hydroxyl( OH) of cellulose fiber and isocyanate group( NCO)of the polyurethane modified organic silicone has formed covalent cross-linking. X-ray diffraction( XRD) analysis revealed that the crystalline region of treated cotton fabrics wasn't changed. The wet rubbing fastness of treated cotton fabrics was increased by approximately rating 1 on average. There was little change of DE values for the polyurethane modified organic silicone. The softness was improved significantly.展开更多
We report a case of a 21-year-old male patient who underwent corneal cross-linking (CXL) due to bilateral progressive keratoconus. Topographical screening of his family members was performed for the detection of possi...We report a case of a 21-year-old male patient who underwent corneal cross-linking (CXL) due to bilateral progressive keratoconus. Topographical screening of his family members was performed for the detection of possible familial keratoconus and showed abnormal topographical patterns resembling to Forme Fruste Keratoconus (FFK) in all the members of his family. The reported keratoconic patient that underwent CXL was the only individual of this family that referred eye rubbing in his personal ocular history;ocular and medical history of the other family members was clear. Eye rubbing could be a possible adjuvant risk factor that contributes to conversion of FFK to clinical progressive keratoconus.展开更多
Background: Frictional melanosis of rubbing inner thighs is a common problem among Iraqi females causing great psychological and cosmetic impact. It might simulate lifa disease but it is a different entity. It is unfo...Background: Frictional melanosis of rubbing inner thighs is a common problem among Iraqi females causing great psychological and cosmetic impact. It might simulate lifa disease but it is a different entity. It is unfortunately not reported in the medical literatures although commonly encountered in daily clinical practice. Objective: To evaluate the hyperpigmentation of inner aspects of thighs in Iraqi females as an isolated pigmentary problem. Patient and Methods: Sixty patients with frictional melanosis of rubbing thighs were seen in Department of Dermatology, Baghdad Teaching Hospital in this case descriptive, clinical and histopathological study, during the period from April 2011 to March 2012. Any associated skin problems were also noticed like folliculitis and boils at area of friction. Forty individuals were enrolled in the present work as the healthy control group. The pigmentation was assessed by clinical, Wood’s light and histopathological examinations (H&E and Fontana stains). Body mass index was obtained for all patients and obesity was graded according to WHO recommendations. Results: The ages of patients ranged between 19 - 52 (32.86 ± 7.65) years, with 59 (98.3%) females and 1 (1.6%) male. By Wood’s light examination, accentuation in pigmentation was observed in 39 (58%) patients, while 21 (42%) of lesions showed no change. Body mass index was ranged from 23.3 - 43.6 (34.04 ± 4.13), history of vigorous rubbing of pigmented area with washing tool (lifa) was positive in 46 (76.6%) patients. Skin biopsies in 10 patients showed pure dermal melanophages in 3 of biopsies with slight melanosis of basal layer of epidermis, while the other 7 biopsies showed mainly increase in basal melanin. There was a statistically significant association between obesity and the severity of pigmentation of the inner thighs. Forty control individuals (2 males and 38 females) were assessed, their ages ranged from 19 - 50 (31.72 ± 6.40) years. All females were within normal weight while males were overweight and BMI was ranged from 19.7 - 28.2 (22.49 ± 1.84). All control individuals showed no pigmentation of inner aspects of thighs. Conclusion: Frictional melanosis of rubbing thighs is considered a new entity which had been not reported before in the medical literatures. This is a disease of mostly young obese females and the effective therapy is weight reduction and possibly liposuction.展开更多
The aim of this paper is to gain insight into the nonlinear vibration feature of a dynamic model of a gas turbine.First,a rod fastening rotor-bearing coupling model with fixed-point rubbing is proposed,where the fract...The aim of this paper is to gain insight into the nonlinear vibration feature of a dynamic model of a gas turbine.First,a rod fastening rotor-bearing coupling model with fixed-point rubbing is proposed,where the fractal theory and the finite element method are utilized.For contact analysis,a novel contact force model is introduced in this paper.Meanwhile,the Coulomb model is adopted to expound the friction characteristics.Second,the governing equations of motion of the rotor system are numerically solved,and the nonlinear dynamic characteristics are analyzed in terms of the bifurcation diagram,Poincarémap,and time history.Third,the potential effects provided by contact degree of joint interface,distribution position,and amount of contact layer are discussed in detail.Finally,the contrast analysis between the integral rotor and the rod fastening rotor is conducted under the condition of fixed-point rubbing.展开更多
This study focuses on<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">comparison between Enzyme Wash and Bleach Wash (Traditional vs. Sus...This study focuses on<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">comparison between Enzyme Wash and Bleach Wash (Traditional vs. Sustainable Washing Machine) the physical and color fastness to rubbing properties</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of denim garments.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">For this experiment indigo dyed cotton denim garments (trousers) were chosen which</span><span style="font-family:Verdana;"> were </span><span style="font-family:Verdana;">98% cotton and 2% spandex and processed by enzyme with the concentration of 2 g/l, </span><span style="font-family:Verdana;">and the </span><span style="font-family:Verdana;">temperature </span><span style="font-family:Verdana;">of </span><span style="font-family:Verdana;">45<span style="color:#555554;font-family:Helvetica, Tahoma, Arial, sans-serif;font-size:14px;white-space:normal;background-color:#FFFFFF;">°</span>C. In another work, enzyme treated denim garments </span><span style="font-family:Verdana;">were </span><span style="font-family:Verdana;">used for bleach wash with the concentration of 2 g/l, temperature 45<span style="white-space:normal;color:#555554;font-family:Helvetica, Tahoma, Arial, sans-serif;font-size:14px;background-color:#FFFFFF;">°</span><span style="font-family:Verdana;white-space:normal;">C</span> and those samples ha</span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> been processed by traditional and sustainable washing machine. After completing process, the sample properties have been compared like rubbing, tearing and tensile properties. After comparing result the</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">color fastness to rubbing of enzyme wash was poor in traditional and sustainable machine</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">and</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">tensile strength, tearing strength properties down in traditional machine but the</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">color fastness to rubbing of bleach wash was </span><span style="font-family:Verdana;">good</span><span style="font-family:Verdana;"> in sustainable machine than traditional machine</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">and a little bit lesser tensile and tearing properties in sustainable process.</span>展开更多
The rubbing between rotors and determiners is the common mechanic vibration fault in the operation of rotation machinery. During the operation of equipment, in order to meet the demand of high speed and efficiency of ...The rubbing between rotors and determiners is the common mechanic vibration fault in the operation of rotation machinery. During the operation of equipment, in order to meet the demand of high speed and efficiency of machinery, the gap between the active and passive parts of the rotor system become smaller, which results in the common rubbing fault of rotors and stators. This essay studies the fault diagnosis of high speed rotors based on invented instrument and shows the measurement and research of the signals of rubbing failure of high speed rotors. The research introduces the designed software and hardware which are experimented and testified on Bentley rotor experiment platform. The system has theoretical and applicative meaning in practical projects.展开更多
基金Project supported by the National Science and Technology Major Project of China (No. 2017-V-0009)the National Natural Science Foundation of China (Nos. 12032015 and 12121002)the National Funding Program for Postdoctoral Researchers of China (No. GZC20231586)。
文摘Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.
基金the financial support from the National Natural Science Foundation of China (52125301 and 52203123)the Fundamental Research Funds for the Central Universitiespartially sponsored by the Double First-Class Construction Funds of Sichuan University。
文摘The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and beyond.Herein,by learning from the pencil-writing process,a facile solid-ink rubbing technology(SIR-tech)is invented to address the above challenge.The solid-ink is exampled by rational combination of liquid metal and graphite particles.By harnessing the synergistic effects between rubbing and adhesion,controllable metallic skin is successfully formed onto metals,woods,ceramics,and plastics without limitation in size and shape.Moreover,outperforming pure liquid-metal coating,the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing.The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well.For applications,the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils.Meanwhile,advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from-196 to 120℃.This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.
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.
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.
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.
文摘The nonlinear dynamic behavior of a rubbing rotor system was studied with a mathematical model established with the eccentricity and interaction between bending and torsional vibrations taken into consideration. The nonlinear vibrational response of a rubbing rotor was analyzed using numerical integral, spectroscopic analysis and Poince mapping method, which made it possible to have better understanding of the vibrational characteristics of partial rubbing and complete circular rubbing rotors. The numerical results reveal the response of torsional vibration mainly takes a form of superchronous motion, and its frequency decreases as the rotational speed increases when partial rubbing occurs, and the response of torsional vibration is synchronous when complete circular rubbing occurs. The comparison of the dynamics of rubbing rotors with and without the interaction between bending and torsional vibrations shows the interaction between bending and torsional vibrations advances the rotational speed, at which the response of bending vibration changes from a synchronous motion into a quasi periodic motion, and the interaction between bending and torsional vibrations reduces stability of the rubbing rotor.
文摘Because of the effect of unbalance excitation and nonlinear magnetic force, the large vibration of the rotor supported by active magnetic bearing(AMB) will go beyond the radial gap of the bearing, even causing mechanical touch-rubbing when the system works at an operational speed closer to the critical speed. In order to investigate this problem, the linear model and nonlinear model of the single mass symmetric rigid rotor system supported by AMB are established respectively and the corresponding transfer functions of close-loop system are given. To pass through the numerical calculation by using MATLAB/Simulink, the effect of both the unbalance response and threshold speed of touch-rubbing of the system subjected to nonlinear magnetic forces and nonlinear output current of power amplifier are studied. Furthermore, threshold speed of touch-rubbing of the rotor-bearing system is defined and the results of numerical simulation are presented. Finally, based on above studies, two methods of increasing the touch-rubbing threshold speed are discussed.
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 the elastic supports,the finite element model of rotor-bladed disk-casing system is established using commercial software ANSYS/LS-DYNA.Assuming that broken blade is released from the disk,the complicate rubbing responses of unbalanced rotor-bladed disk-casing system are studied under different operational speeds.In addition,influences of both plastic deformation of blade and casing failure are analyzed.The results show that there exist some multiple even fractional frequencies in the transient and steady vibration responses of unbalanced rotor.Besides,one nodal diameter vibration of bladed disk coupling with the lateral vibration of the shaft as well as the first order bending vibration of blade can be excited under low operational speed,while the first order bending vibration of blade coupling with the lateral vibration of disk-shaft is easily excited under high operational speed.During rubbing process,three distinct contact states can be observed:broken blade-casing contact,broken blade-blade component-casing contact and broken blade-casing contact/blade component-casing contact/blade selfcontact.It is worth noting that the third contact state is related to the operational speed.With the increase of operational speed,self-contact in the blade may occur.
基金supported by the In Coming Fellowship of Royal Society of the UK and the National Natural Science Foundation of China(10672006)
文摘The phase characteristic of a disk rubbing with a ring supported elastically is investigated and used to explain the mechanism of stiffness increase phenomenon. As long as the rubbing is maintained, the averaged phase difference between the disk and the rotating mass on the disk is defi- nitely less than π/2. When the rubbing finishes, the phase difference quickly approaches to 7r. This behavior is inde- pendent of the physics parameters of the rubbing system. The theoretical results are qualitatively verified with experiments.
文摘Polyurethane modified organic silicone was successfully prepared from hydroxyl-terminated polyether modified silicone,toluene-2,4-diisocyanate( TDI), and NaHSO3. The chemical structure of the polyurethane modified organic silicone was characterized by FT-IR and1H-NMR. The polymer film on the cotton surface was investigated by scanning electron microscopy( SEM) and the results showed that a thin polymer film was successfully formed. The FT-IR of treated cotton fabrics indicated that hydroxyl( OH) of cellulose fiber and isocyanate group( NCO)of the polyurethane modified organic silicone has formed covalent cross-linking. X-ray diffraction( XRD) analysis revealed that the crystalline region of treated cotton fabrics wasn't changed. The wet rubbing fastness of treated cotton fabrics was increased by approximately rating 1 on average. There was little change of DE values for the polyurethane modified organic silicone. The softness was improved significantly.
文摘We report a case of a 21-year-old male patient who underwent corneal cross-linking (CXL) due to bilateral progressive keratoconus. Topographical screening of his family members was performed for the detection of possible familial keratoconus and showed abnormal topographical patterns resembling to Forme Fruste Keratoconus (FFK) in all the members of his family. The reported keratoconic patient that underwent CXL was the only individual of this family that referred eye rubbing in his personal ocular history;ocular and medical history of the other family members was clear. Eye rubbing could be a possible adjuvant risk factor that contributes to conversion of FFK to clinical progressive keratoconus.
文摘Background: Frictional melanosis of rubbing inner thighs is a common problem among Iraqi females causing great psychological and cosmetic impact. It might simulate lifa disease but it is a different entity. It is unfortunately not reported in the medical literatures although commonly encountered in daily clinical practice. Objective: To evaluate the hyperpigmentation of inner aspects of thighs in Iraqi females as an isolated pigmentary problem. Patient and Methods: Sixty patients with frictional melanosis of rubbing thighs were seen in Department of Dermatology, Baghdad Teaching Hospital in this case descriptive, clinical and histopathological study, during the period from April 2011 to March 2012. Any associated skin problems were also noticed like folliculitis and boils at area of friction. Forty individuals were enrolled in the present work as the healthy control group. The pigmentation was assessed by clinical, Wood’s light and histopathological examinations (H&E and Fontana stains). Body mass index was obtained for all patients and obesity was graded according to WHO recommendations. Results: The ages of patients ranged between 19 - 52 (32.86 ± 7.65) years, with 59 (98.3%) females and 1 (1.6%) male. By Wood’s light examination, accentuation in pigmentation was observed in 39 (58%) patients, while 21 (42%) of lesions showed no change. Body mass index was ranged from 23.3 - 43.6 (34.04 ± 4.13), history of vigorous rubbing of pigmented area with washing tool (lifa) was positive in 46 (76.6%) patients. Skin biopsies in 10 patients showed pure dermal melanophages in 3 of biopsies with slight melanosis of basal layer of epidermis, while the other 7 biopsies showed mainly increase in basal melanin. There was a statistically significant association between obesity and the severity of pigmentation of the inner thighs. Forty control individuals (2 males and 38 females) were assessed, their ages ranged from 19 - 50 (31.72 ± 6.40) years. All females were within normal weight while males were overweight and BMI was ranged from 19.7 - 28.2 (22.49 ± 1.84). All control individuals showed no pigmentation of inner aspects of thighs. Conclusion: Frictional melanosis of rubbing thighs is considered a new entity which had been not reported before in the medical literatures. This is a disease of mostly young obese females and the effective therapy is weight reduction and possibly liposuction.
基金the National Natural Science Foundation of China(No.12172307)the Key Laboratory of Vibration and Control of Aero-Propulsion System,Ministry of Education,Northeastern University of China(No.VCAME202103)the Fundamental Research Funds for the Central Universities in Southwest Jiaotong University of China(No.2682021ZTPY036)。
文摘The aim of this paper is to gain insight into the nonlinear vibration feature of a dynamic model of a gas turbine.First,a rod fastening rotor-bearing coupling model with fixed-point rubbing is proposed,where the fractal theory and the finite element method are utilized.For contact analysis,a novel contact force model is introduced in this paper.Meanwhile,the Coulomb model is adopted to expound the friction characteristics.Second,the governing equations of motion of the rotor system are numerically solved,and the nonlinear dynamic characteristics are analyzed in terms of the bifurcation diagram,Poincarémap,and time history.Third,the potential effects provided by contact degree of joint interface,distribution position,and amount of contact layer are discussed in detail.Finally,the contrast analysis between the integral rotor and the rod fastening rotor is conducted under the condition of fixed-point rubbing.
文摘This study focuses on<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">comparison between Enzyme Wash and Bleach Wash (Traditional vs. Sustainable Washing Machine) the physical and color fastness to rubbing properties</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of denim garments.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">For this experiment indigo dyed cotton denim garments (trousers) were chosen which</span><span style="font-family:Verdana;"> were </span><span style="font-family:Verdana;">98% cotton and 2% spandex and processed by enzyme with the concentration of 2 g/l, </span><span style="font-family:Verdana;">and the </span><span style="font-family:Verdana;">temperature </span><span style="font-family:Verdana;">of </span><span style="font-family:Verdana;">45<span style="color:#555554;font-family:Helvetica, Tahoma, Arial, sans-serif;font-size:14px;white-space:normal;background-color:#FFFFFF;">°</span>C. In another work, enzyme treated denim garments </span><span style="font-family:Verdana;">were </span><span style="font-family:Verdana;">used for bleach wash with the concentration of 2 g/l, temperature 45<span style="white-space:normal;color:#555554;font-family:Helvetica, Tahoma, Arial, sans-serif;font-size:14px;background-color:#FFFFFF;">°</span><span style="font-family:Verdana;white-space:normal;">C</span> and those samples ha</span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> been processed by traditional and sustainable washing machine. After completing process, the sample properties have been compared like rubbing, tearing and tensile properties. After comparing result the</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">color fastness to rubbing of enzyme wash was poor in traditional and sustainable machine</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">and</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">tensile strength, tearing strength properties down in traditional machine but the</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">color fastness to rubbing of bleach wash was </span><span style="font-family:Verdana;">good</span><span style="font-family:Verdana;"> in sustainable machine than traditional machine</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">and a little bit lesser tensile and tearing properties in sustainable process.</span>
基金supported by the Education and Teaching Research Project of Jieyang Vocational and Technical College(JYC2016Y11)
文摘The rubbing between rotors and determiners is the common mechanic vibration fault in the operation of rotation machinery. During the operation of equipment, in order to meet the demand of high speed and efficiency of machinery, the gap between the active and passive parts of the rotor system become smaller, which results in the common rubbing fault of rotors and stators. This essay studies the fault diagnosis of high speed rotors based on invented instrument and shows the measurement and research of the signals of rubbing failure of high speed rotors. The research introduces the designed software and hardware which are experimented and testified on Bentley rotor experiment platform. The system has theoretical and applicative meaning in practical projects.