Pipeline Inspection Gauge(pig)is an important equipment for oil and gas pipelines during different stages of their operations to perform functions such as dewatering,cleaning,and inspection.Owing to the hyperelasticit...Pipeline Inspection Gauge(pig)is an important equipment for oil and gas pipelines during different stages of their operations to perform functions such as dewatering,cleaning,and inspection.Owing to the hyperelasticity,time and temperature-dependent material behaviour of the sealing disc attached on the pig,the contact between the pig and the pipeline expresses complex behaviour,leading to an uncertainty in the prediction of the pig's frictional force.Knowing the deformation of the sealing discs well is essential and can be highly meaningful for predicting the pig motion,as well as reducing the pigging risks.In this study,the geometrical deformation of the sealing discs with different sizes are investigated through experiments and numerical simulations.The effects of the four nondimensionalized parameters(interference,thickness per pipeline inner diameter,and clamping ratio)of the sealing discs on the deformation behaviour were observed and discussed,and an improved mathematical model for predicting the geometrical deformation of the sealing discs was proposed and verified.With the auxiliary angleαadded in the improved mathematical model,the relative error declines to 1.87%and 3.18%respectively for predicting deformation of the sealing discs in size of 2-inch and 40-inch pig.The results of this study can help better understand the frictional force of a pig with sealing discs,as well as its motion.展开更多
As one of the core parts, the brake discs directly impact the braking and safety performance of vehicles. Traditional surface detection methods of the brake disc have poor robustness due to their reliance on manual fe...As one of the core parts, the brake discs directly impact the braking and safety performance of vehicles. Traditional surface detection methods of the brake disc have poor robustness due to their reliance on manual feature extraction. A detection instrument was designed to focus on the detection. The features were extracted using the improved Gaussian difference algorithm and Hough transform algorithm(IGD-IHT). An identification method for brake disc surface defects was designed in this paper based on the Perception-based Image Quality Evaluator and Dempster rule-improved sparrow search algorithm-Nonlinear echo state network(PIQEDS-ISSA-NESN) to better identify. It was shown in the experiment that the accuracy was more than 97%, the false alarm rate was less than 1.5%, and the false alarm rate was less than 1.5%.展开更多
AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control...AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control subjects were enrolled in the study.One eye of each individual was included and OCT-A scans of optic discs were obtained in a 4.5×4.5 mm^(2) rectangular area.Radial peripapillary capillary(RPC)density,peripapillary retinal nerve fiber layer(pRNFL)thickness,cup volume,rim area,disc area,cup-to-disc(c/d)area ratio,and vertical c/d ratio were obtained automatically using device software.Automated parapapillary choroidal microvasculature(PPCMv)density was calculated using MATLAB software.When the vertical c/d ratio of the optic disc was absent or small cup,it was considered as a crowded disc.RESULTS:The mean signal strength index of OCT-A images was similar between the crowded discs and control eyes(P=0.740).There was no difference in pRNFL between the two groups(P=0.102).There were no differences in RPC density in whole image(P=0.826)and peripapillary region(P=0.923),but inside disc RPC density was higher in crowded optic discs(P=0.003).The PPCMv density in the inner-hemisuperior region was also lower in crowded discs(P=0.026).The pRNFL thickness was positively correlated with peripapillary RPC density(r=0.498,P<0.001).The inside disc RPC density was negatively correlated with c/d area ratio(r=-0.341,P=0.002).CONCLUSION:The higher inside disc RPC density and lower inner-hemisuperior PPCMv density are found in eyes with crowded optic discs.展开更多
The increase in payload capacity of trucks has heightened the demand for cost-effective yet high performance brake discs.In this work,the thermal fatigue and wear of compacted graphite iron brake discs were investigat...The increase in payload capacity of trucks has heightened the demand for cost-effective yet high performance brake discs.In this work,the thermal fatigue and wear of compacted graphite iron brake discs were investigated,aiming to provide an experimental foundation for achieving a balance between their thermal and mechanical properties.Compacted graphite iron brake discs with different tensile strengths,macrohardnesses,specific heat capacities and thermal diffusion coefficients were produced by changing the proportion and strength of ferrite.The peak temperature,pressure load and friction coefficient of compacted graphite iron brake discs were analyzed through inertia friction tests.The morphology of thermal cracks and 3D profiles of the worn surfaces were also discussed.It is found that the thermal fatigue of compacted graphite iron discs is determined by their thermal properties.A compacted graphite iron with the highest specific heat capacity and thermal diffusion coefficient exhibits optimal thermal fatigue resistance.Oxidization of the matrix at low temperatures significantly weakens the function of alloy strengthening in hindering the propagation of thermal cracks.Despite the reduced hardness,increasing the ferrite proportion can mitigate wear loss resulting from low disc temperatures and the absence of abrasive wear.展开更多
As the velocity of a train increases,the corresponding air pumping power consumption of the brake discs increases proportionally.In the present experimental study,a standard axle-mounted brake disc with circumferentia...As the velocity of a train increases,the corresponding air pumping power consumption of the brake discs increases proportionally.In the present experimental study,a standard axle-mounted brake disc with circumferential pillars was analyzed using a 1:1 scale model and a test rig in a wind tunnel.In particular,three upstream velocities were selected on the basis of earlier investigations of trains operating at 160,250,and 400 km/h,respectively.Moreover,3D steady computational fluid dynamics(CFD)simulations of the flow field were conducted to compare with the wind tunnel test outcomes.The results for a 3-car train at 180 km/h demonstrated:(1)good agreement between the air resistance torques obtained from the wind tunnel tests and the related numerical results,with differences ranging from 0.95%to 5.88%;(2)discrepancies ranging from 3.2 to 3.8 N·m;(3)cooling ribs contributing more than 60%of the air resistance torque;(4)the fast rotation of brake discs causing a significantly different flow field near the bogie area,resulting in 25 times more air pumping power loss than that obtained in the stationary brake-disc case.展开更多
The noncarbonaceous Ediacaran discs of variable morphologies from the Jodhpur Sandstone Formation of the Marwar Supergroup, western Rajasthan, suggest different biologic affinities of plant and animal kingdom. These d...The noncarbonaceous Ediacaran discs of variable morphologies from the Jodhpur Sandstone Formation of the Marwar Supergroup, western Rajasthan, suggest different biologic affinities of plant and animal kingdom. These discs are commonly preserved on the bedding surfaces of siliciclastic sandstone and shale in strong positive relief and appear to possess a flexible to rigid body. Discs assignable to Aspidella, Cyclomedusa, Nimbia and Heimalora;all possibly inclining towards cnidarian affinity are being reported from the sandstone beds in Sursagar area. Variable morphologies among discs preserved in siliciclastic shale beds from the Artiya Kalan area support scyphozoan affinity (earlier named Marsonia from the same locality) and cnidarian affinity for small discs comparable with Funisia (considered being the first animals having sexual reproduction). Disc’s morphologies also suggest ephyra stage of Aurilia (a cnidarian form) or budding stages of some fungi, like Germinosphaera (multicellular benthic fungal fossils) and noncarbonaceous discs with well preserved wrinkles and folds like in Chuaria. Discs from the Jodhpur Sandstone, may at times display taphonomic interplay, but consistency and repetition in morphology support variable biological affinities representing diverse assemblage and advance ecosystem prevailing during Ediacaran period. A degree of genetic variability can be expected within any taxa, and this may be compounded by preservation factors affecting the Jodhpur Ediacaran discs. Sudden increase in size or gigantism is a common feature of Ediacaran life, which is evident in case of Jodhpur discs also. On the basis of fossil assemblage, the Jodhpur Group (the Marwar Supergroup) is regionally correlated with the Bhander Group of the Vindhyan Supergroup and Krol Group of Lesser Himalaya. Globally, the assemblage is comparable with the Long Mynd Group, Shropshire, UK, Fermuse Formation Newfoundland, South Australia, Russia and Norway.展开更多
An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes...An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes important to assess the stability of a soil-nailed system.In the present study,an investigation into the pullout behaviour of soil nail with circular discs along the shaft has been carried out by a threedimensional finite element analysis using Abaqus/Explicit routine.A total of 67 simulations have been performed to accurately predict the pullout behaviour of soil nail.The soil nail under study has circular discs along its shaft varying in numbers from 1 to 4.The pullout of this soil nail in a pullout test box has been simulated with a constant overburden pressure of 20 kPa acting on the nail.The pullout load edisplacement characteristics,stresses around soil nail and failure mechanism during pullout are studied.Variations of dimensionless factors such as normalised pullout load factor and bearing capacity factor have been obtained with different combinations of parameters in terms of relative disc spacing ratio,anchorage length ratio,embedment ratio,diameter ratio and displacement ratio.From the results of analyses,it is found that nail with more circular discs requires higher pullout load.There are critical relative disc spacing ratio and diameter ratio which significantly affect the pullout behaviour of nail.展开更多
Ediacaran discs from the Jodhpur Sandstone of the Marwar Supergroup, Rajasthan, exhibit a wide size ranging from a few millimetres to 75 cm in diameter. Exceptionally large size of the discs in these rocks represent t...Ediacaran discs from the Jodhpur Sandstone of the Marwar Supergroup, Rajasthan, exhibit a wide size ranging from a few millimetres to 75 cm in diameter. Exceptionally large size of the discs in these rocks represent the largest reported so far from any Ediacaran assemblage. Although, larger medu-soid discs have been reported from USA, they are from the middle Cambrian and even younger rocks. Presence of microbial mats and weed-like structures with well preserved hold fasts and horizontal rhizome-like structures in association with some of these large-sized discs support their animal affinity, which probably feed on this weed-like vegetations. This association also supports their benthic habitat. Unlike the general trend of sudden increase in size of organisms in Ediacaran period and further decrease in size during Cambrian, these discs continued increasing in size in Cambrian also.展开更多
Objective: To assess the validity, responsiveness, and test-retest reliability of DISCs (Depression Intensity Scale Circles) as a simple screening tool for depression in patients with cognitive or communicative defici...Objective: To assess the validity, responsiveness, and test-retest reliability of DISCs (Depression Intensity Scale Circles) as a simple screening tool for depression in patients with cognitive or communicative deficits following acquired brain injury. Design: Cohort analysis of consecutive patients entered into an integrated care pathway for screening and management of depression in the context of rehabilitation. Setting: Regional neurological rehabilitation service in the UK. Participants: 114 patients with complex disabilities caused by acquired brain injury (mean (SD) age, 42.8 (14.5) years). Main outcome measures: DISCs (a graphic rating scale depicting six circles with increasing proportion of dark shading), Numbered Graphic Rating Scale (NGRS), Yale single question (“Do you often feel sad or depressed”), Beck Depression Inventory-II (BDI-II), DSM-IV criteria for depression. Results: At initial assessment the DISCs correlated with total BDI-II scores (Spearman ρ= 0.66, P < 0.001), NGRS (ρ= 0.87, P < 0.001), and DSM-IV (ρ= 0.59, P < 0.001).A DISCs score≥2 identified depression (major or minor) according to DSM-IV criteria with 60%sensitivity, 87%specificity, 75%positive predictive value, and 77%negative predictive value. Test-retest reliability after 24 hours (n = 66) showed“excellent”.level of agreement (weighted κ= 0.84). In 45 patients who received intervention for depression, the DISCs showed a significant change in response to treatment (Wilcoxon; P < 0.001). Conclusions: DISCs had acceptable convergent validity, reliability, and responsiveness as a simple graded tool for screening and assessment of depression in patients with complex disabilities following acquired brain injury. It warrants further investigation in patients with more profound language and cognitive deficits for which it is primarily intended.展开更多
Turbulence is a fundamentally interesting physical phenomenon which is of fundamental interest. Indeed, it is at the origin of several industrial applications, the control of energy in these industrial applications pa...Turbulence is a fundamentally interesting physical phenomenon which is of fundamental interest. Indeed, it is at the origin of several industrial applications, the control of energy in these industrial applications pass by the comprehension and the modelling of turbulent flows. Several factors are at the origin of turbulence in the complex flows, among these factors, we can quote the effect of wings in the rotating flows. The interest of this work is to model and to simulate numerically the effect of wings on the level of turbulence in the flow between two contra-rotating discs. We have fixed on these two discs eight wings uniformly distributed and we have varied the height of the wings to have eleven values from 0 to 18 mm by maintaining the same Reynolds number of rotation. The numerical tool is based on a statistical model in a point using the closing of the second order of the transport equations of the Reynolds stresses （Reynolds Stress Model： RSM）. We have modelled wings effect on the flow by a source term added to the equation tangential speed. The results of the numerical simulation showed that all the average and fluctuating variables are affected the value of the kinetic energy of turbulence as those of Reynolds stresses increase with the height of the wings.展开更多
We extend the research of axisymmetric waves in accretion discs with three-dimensional structure to the case that vertical self-gravity of the discs is included. We derive and analyze the dispersion relation and solve...We extend the research of axisymmetric waves in accretion discs with three-dimensional structure to the case that vertical self-gravity of the discs is included. We derive and analyze the dispersion relation and solve the eigenfunctions numerically. The following results have been reached: vertical self-gravity expands the forbidden region of the wave propagation. As the influence of the vertical self-gravity increases, the group velocities of the waves get smaller and the vertical nodes of the wave shrink to the middle plane of the disc.展开更多
Gonad development requires a coordinated soma-germline interaction that ensures renewal and differentiation of germline and somatic stem cells to ultimately produce mature gametes. The Drosophila tumour suppressor gen...Gonad development requires a coordinated soma-germline interaction that ensures renewal and differentiation of germline and somatic stem cells to ultimately produce mature gametes. The Drosophila tumour suppressor gene discs large （dig） encodes a septate junction protein functioning during epithelial polarization, asymmetric neuroblast division, and formation of neuromuscular junctions. Here, we report the role of dig in testis development and its critical function in somatic cyst cells （SCCs）. In these cells dig is primarily required for their survival and expansion, and contributes to spermatocyte cyst differentiation. Cell death primarily occurred in SCCs at the end of spermatogonial amplification at a time when Dig becomes restricted in wild-type （wt） testes to the distal somatic cells capping the growing spermatocyte cysts. RNAi depletion of dig transcripts in early SCCs fully prevented testis development, whereas depletion in late SCCs resulted in a breakdown of spermatocyte cyst structure and germ cell individualization. Specific dig expression in SCCs resulted in developmental rescue of dig mutant testes, whereas its expression in germ cells exerted no such effect, dig overexpression in wt testes led to spermatocyte cyst expansion at the expense of spermatogonial cysts. Our data demonstrate that dig is essentially required in SCCs for their survival, expansion, and differentiation, and for the encapsulation of the germline cells.展开更多
We study the stability of accretion disc around magnetised stars. Starting from the equations of magnetohydrodynamics we derive equations for linearized perturbation of geometrically thin, optically thick axisymmetric...We study the stability of accretion disc around magnetised stars. Starting from the equations of magnetohydrodynamics we derive equations for linearized perturbation of geometrically thin, optically thick axisymmetric accretion disc with an internal dynamo around magnetized stars. The structure and evolution of such discs are governed by an evolution equation for matter surface density ∑(R,T). Using the time-dependent equations for an accretion disc we do a linear stability analysis of our steady disc solutions in the presence of the magnetic field generated due to an internal dynamo.展开更多
By solving analytically the various types of Lane-Emden equations with rotation, we have discovered two new coupled fundamental properties of rotating, self-gravitating, gaseous discs in equilibrium: isothermal discs ...By solving analytically the various types of Lane-Emden equations with rotation, we have discovered two new coupled fundamental properties of rotating, self-gravitating, gaseous discs in equilibrium: isothermal discs must, on average, exhibit strict power-law density profiles in radius x on their equatorial planes of the form , where A and k-1 are the integration constants;and “flat” rotation curves precisely such as those observed in spiral galaxy discs. Polytropic discs must, on average, exhibit strict density profiles of the form , where n is the polytropic index;and “flat” rotation curves described by square roots of upper incomplete gamma functions. By “on average”, we mean that, irrespective of the chosen boundary conditions, the actual profiles must oscillate around and remain close to the strict mean profiles of the analytic singular equilibrium solutions. We call such singular solutions the “intrinsic” solutions of the differential equations because they are demanded by the second-order equations themselves with no regard to the Cauchy problem. The results are directly applicable to gaseous galaxy discs that have long been known to be isothermal and to protoplanetary discs during the extended isothermal and adiabatic phases of their evolution. In galactic gas dynamics, they have the potential to resolve the dark matter—modified gravity controversy in a sweeping manner, as they render both of these hypotheses unnecessary. In protoplanetary disc research, they provide observers with a powerful new probing tool, as they predict a clear and simple connection between the radial density profiles and the rotation curves of self-gravitating discs in their very early (pre-Class 0) phases of evolution.展开更多
The aim of the present study was to compare the relationship of morphologically defined non-bulging/herni-ated, bulging and herniated intervertebral lumbar discs with quantitative apparent diffusion coefficient （ADC...The aim of the present study was to compare the relationship of morphologically defined non-bulging/herni-ated, bulging and herniated intervertebral lumbar discs with quantitative apparent diffusion coefficient （ADC）. Thirty-two healthy volunteers and 28 patients with back pain or sciatica were examined by MRI. All intervertebral lumbar discs from L1 to S1 were classified according to morphological abnormality and degenerated grades. The ADC values of nucleus pulposus （NP） were measured and recorded. The significant differences about mean ADC values of NP were found between non-bulging/herniated discs and bulging discs as well as herniated discs （P 0.05）, whereas there were no significant differences in ADC values between bulging and herniated discs （P 0.05）. Moreover, statistically significant relationship was found in the mean ADC values of NP between ＂non-bulging/herniated and non-degenerated discs＂ and ＂non-bulging/herniated degenerated discs＂ as well as herniated discs （P 0.05）. Linear regression analysis between ADC value and disc level revealed an inverse correlation （r = -0.18）. The ADC map of the NP is a potentially useful tool for the quantitative assessment of componential and molecular alterations accompanied with lumbar disc abnormalities.展开更多
Leaf senescence is often caused by water deficit and the chimeric gene PSA612-1PT is an auto-regulated gene delaying leaf senescence. Using in vitro leaf discs culture system, the changes of contents of chlorophylls, ...Leaf senescence is often caused by water deficit and the chimeric gene PSA612-1PT is an auto-regulated gene delaying leaf senescence. Using in vitro leaf discs culture system, the changes of contents of chlorophylls, carotenoids, soluble protein and thiobarbituric acid reactive substance （TBARS） and antioxidant enzymes activities were investigated during leaf senescence of PSA612-1PT modified gerbera induced by osmotic stress compared with the control plant （wild type）. Leaf discs were incubated in 20%, 40% （w/v） polyethylene glycol （PEG） 6 000 nutrient solution for 20 h under continuous light [ 130 μmol/（m^2·s）]. The results showed that the contents of chlorophylls, carotenoids and soluble protein were decreased by osmotic stress with the decrease being more pronounced at 40% PEG, but that, at the same PEG concentration the decrease in the transgenic plants was significantly lower than that in the control plant. The activities of superoxide dismutase （SOD）, catalases （CAT）, ascorbate peroxidase （APX）, guaiacol peroxidase （GPX） and dehydroascorbate reductase （DHAR） were stimulated by PEG treatment. However, the increases were higher in PSA612-IPT transgenic plants than in the control plants, particularly at 40% PEG treatment. Lipid peroxidation （TBARS content） was increased by PEG treatment with the increase being much lower in transgenic plant than in the control plant. It could be concluded that the increases in the activities ofantioxidant enzymes including SOD, CAT, APX, GPX and DHAR were responsible for the delay of leaf senescence induced by osmotic stress.展开更多
Objective: To assess the effects of axial vibrations on gene expression and lumbar intervertebral disc degeneration in vivo. Methods: A modified bipedal rat model was established using a brachial plexus rhizotomy appr...Objective: To assess the effects of axial vibrations on gene expression and lumbar intervertebral disc degeneration in vivo. Methods: A modified bipedal rat model was established using a brachial plexus rhizotomy approach to imitate human upright posture. The experimental animals were randomly divided into three groups: control, vertical vibration, and whole-body vibration. Gene expression in degeneration of the intervertebral discs was assessed by reverse transcription-quantitative polymerase chain reaction. Results: The expression of aggrecan, Col1α1, Col2α1, and decorin were shown to be up-regulated in 14-week-old rats in the vertical vibration and whole-body vibration groups, whereas biglycan and versican expression was down-regulated in 14-week-old rats of the two experimental groups. Furthermore, biglycan and versican expression levels were shown to be lower in the whole-body vibration group than in the vertical vibration group(P<0.05). Conclusions: This in-vivo study demonstrated that vibrations can influence the expression of anabolic genes. Furthermore, whole-body vibrations seem to have a greater effect in this regard than vertical vibrations. A new method is expected to relieve the low back pain of the patients through our research.展开更多
KLD-12 peptide with a sequence of AcN-KLDLKLDLKLDL-CNH2 was synthesized and its biocompatibility was assessed in animals. Rabbit MSCs were cultured in the hydrogel for 2 weeks. Live cells were counted by using Calcein...KLD-12 peptide with a sequence of AcN-KLDLKLDLKLDL-CNH2 was synthesized and its biocompatibility was assessed in animals. Rabbit MSCs were cultured in the hydrogel for 2 weeks. Live cells were counted by using Calcein-AM/P1 fluorescence staining. MTT was employed to assess the viability of MSCs cultured in KLD-12 peptide solution of 0.01%, 0.03%, and 0.05%. Hemolysis test, skin irritation test and implantation test were conducted to evaluate its biocompatibility with host tissues. Our results demonstrated that the MSCs in hydrogel grew well and maintained round shape. Cell survival rate was 92.15% （mean： 92.15%±1.17%） at the 7th day and there was no difference in survival rate between day 7 and day 14. Cell proliferation test showed that the A value of the KLD-12 solutions was not significantly different from that of control groups （complete culture media） （P〉0.05） at the 24th and 48th h. The hemolysis rate of KLD-12 solution was 0.112%. Skin irritation test showed that the skin injected with KLD-12 solution remained normal and the score of skin irritation was 0. The histological examination with HE staining exhibited that the skin layers were clear and there was no infiltration with neutrophilic granulocytes and lymphocytes. It is concluded that KLD-12 peptide hydrogel bad a good biocompatibility with host rabbit and MSCs, and KLD-12 pep- tide hydrogel can provide an appropriate microenvironment for MSCs.展开更多
基金supported by Key Technologies Research and Development Program(Grant No.SQ2022YFC2806103)and the National Natural Science Foundation of China(Grant No.51509259).
文摘Pipeline Inspection Gauge(pig)is an important equipment for oil and gas pipelines during different stages of their operations to perform functions such as dewatering,cleaning,and inspection.Owing to the hyperelasticity,time and temperature-dependent material behaviour of the sealing disc attached on the pig,the contact between the pig and the pipeline expresses complex behaviour,leading to an uncertainty in the prediction of the pig's frictional force.Knowing the deformation of the sealing discs well is essential and can be highly meaningful for predicting the pig motion,as well as reducing the pigging risks.In this study,the geometrical deformation of the sealing discs with different sizes are investigated through experiments and numerical simulations.The effects of the four nondimensionalized parameters(interference,thickness per pipeline inner diameter,and clamping ratio)of the sealing discs on the deformation behaviour were observed and discussed,and an improved mathematical model for predicting the geometrical deformation of the sealing discs was proposed and verified.With the auxiliary angleαadded in the improved mathematical model,the relative error declines to 1.87%and 3.18%respectively for predicting deformation of the sealing discs in size of 2-inch and 40-inch pig.The results of this study can help better understand the frictional force of a pig with sealing discs,as well as its motion.
基金bankrolled by the West Coast New Area University President Fund Special Project of Qingdao Technical College (Grant No.39100101)the National Key Research and Development Plan (Grant No.2017YFF0108100)+2 种基金the Basic Research Projects of Science,Education,and Industry Integration Pilot Project of the Qilu University of Technology (Shandong Academy of Sciences)(Grant No. 2023PX031)the Natural Science Foundation of Qingdao under Grants No. 23-2-1-121-zyyd-jchthe project ZR2023QE212 supported by Shandong Provincial Natural Science Foundation。
文摘As one of the core parts, the brake discs directly impact the braking and safety performance of vehicles. Traditional surface detection methods of the brake disc have poor robustness due to their reliance on manual feature extraction. A detection instrument was designed to focus on the detection. The features were extracted using the improved Gaussian difference algorithm and Hough transform algorithm(IGD-IHT). An identification method for brake disc surface defects was designed in this paper based on the Perception-based Image Quality Evaluator and Dempster rule-improved sparrow search algorithm-Nonlinear echo state network(PIQEDS-ISSA-NESN) to better identify. It was shown in the experiment that the accuracy was more than 97%, the false alarm rate was less than 1.5%, and the false alarm rate was less than 1.5%.
文摘AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control subjects were enrolled in the study.One eye of each individual was included and OCT-A scans of optic discs were obtained in a 4.5×4.5 mm^(2) rectangular area.Radial peripapillary capillary(RPC)density,peripapillary retinal nerve fiber layer(pRNFL)thickness,cup volume,rim area,disc area,cup-to-disc(c/d)area ratio,and vertical c/d ratio were obtained automatically using device software.Automated parapapillary choroidal microvasculature(PPCMv)density was calculated using MATLAB software.When the vertical c/d ratio of the optic disc was absent or small cup,it was considered as a crowded disc.RESULTS:The mean signal strength index of OCT-A images was similar between the crowded discs and control eyes(P=0.740).There was no difference in pRNFL between the two groups(P=0.102).There were no differences in RPC density in whole image(P=0.826)and peripapillary region(P=0.923),but inside disc RPC density was higher in crowded optic discs(P=0.003).The PPCMv density in the inner-hemisuperior region was also lower in crowded discs(P=0.026).The pRNFL thickness was positively correlated with peripapillary RPC density(r=0.498,P<0.001).The inside disc RPC density was negatively correlated with c/d area ratio(r=-0.341,P=0.002).CONCLUSION:The higher inside disc RPC density and lower inner-hemisuperior PPCMv density are found in eyes with crowded optic discs.
基金supported by the Science and Technology Innovation Development Project of Yantai(No.2023ZDX016)。
文摘The increase in payload capacity of trucks has heightened the demand for cost-effective yet high performance brake discs.In this work,the thermal fatigue and wear of compacted graphite iron brake discs were investigated,aiming to provide an experimental foundation for achieving a balance between their thermal and mechanical properties.Compacted graphite iron brake discs with different tensile strengths,macrohardnesses,specific heat capacities and thermal diffusion coefficients were produced by changing the proportion and strength of ferrite.The peak temperature,pressure load and friction coefficient of compacted graphite iron brake discs were analyzed through inertia friction tests.The morphology of thermal cracks and 3D profiles of the worn surfaces were also discussed.It is found that the thermal fatigue of compacted graphite iron discs is determined by their thermal properties.A compacted graphite iron with the highest specific heat capacity and thermal diffusion coefficient exhibits optimal thermal fatigue resistance.Oxidization of the matrix at low temperatures significantly weakens the function of alloy strengthening in hindering the propagation of thermal cracks.Despite the reduced hardness,increasing the ferrite proportion can mitigate wear loss resulting from low disc temperatures and the absence of abrasive wear.
基金supported by the National Key Research and Development Program of China(2020YFA0710901)the National Natural Science Foundation of China(12002395)Natural Science Foundation of Hunan Province(Grant No.2023JJ30643).
文摘As the velocity of a train increases,the corresponding air pumping power consumption of the brake discs increases proportionally.In the present experimental study,a standard axle-mounted brake disc with circumferential pillars was analyzed using a 1:1 scale model and a test rig in a wind tunnel.In particular,three upstream velocities were selected on the basis of earlier investigations of trains operating at 160,250,and 400 km/h,respectively.Moreover,3D steady computational fluid dynamics(CFD)simulations of the flow field were conducted to compare with the wind tunnel test outcomes.The results for a 3-car train at 180 km/h demonstrated:(1)good agreement between the air resistance torques obtained from the wind tunnel tests and the related numerical results,with differences ranging from 0.95%to 5.88%;(2)discrepancies ranging from 3.2 to 3.8 N·m;(3)cooling ribs contributing more than 60%of the air resistance torque;(4)the fast rotation of brake discs causing a significantly different flow field near the bogie area,resulting in 25 times more air pumping power loss than that obtained in the stationary brake-disc case.
文摘The noncarbonaceous Ediacaran discs of variable morphologies from the Jodhpur Sandstone Formation of the Marwar Supergroup, western Rajasthan, suggest different biologic affinities of plant and animal kingdom. These discs are commonly preserved on the bedding surfaces of siliciclastic sandstone and shale in strong positive relief and appear to possess a flexible to rigid body. Discs assignable to Aspidella, Cyclomedusa, Nimbia and Heimalora;all possibly inclining towards cnidarian affinity are being reported from the sandstone beds in Sursagar area. Variable morphologies among discs preserved in siliciclastic shale beds from the Artiya Kalan area support scyphozoan affinity (earlier named Marsonia from the same locality) and cnidarian affinity for small discs comparable with Funisia (considered being the first animals having sexual reproduction). Disc’s morphologies also suggest ephyra stage of Aurilia (a cnidarian form) or budding stages of some fungi, like Germinosphaera (multicellular benthic fungal fossils) and noncarbonaceous discs with well preserved wrinkles and folds like in Chuaria. Discs from the Jodhpur Sandstone, may at times display taphonomic interplay, but consistency and repetition in morphology support variable biological affinities representing diverse assemblage and advance ecosystem prevailing during Ediacaran period. A degree of genetic variability can be expected within any taxa, and this may be compounded by preservation factors affecting the Jodhpur Ediacaran discs. Sudden increase in size or gigantism is a common feature of Ediacaran life, which is evident in case of Jodhpur discs also. On the basis of fossil assemblage, the Jodhpur Group (the Marwar Supergroup) is regionally correlated with the Bhander Group of the Vindhyan Supergroup and Krol Group of Lesser Himalaya. Globally, the assemblage is comparable with the Long Mynd Group, Shropshire, UK, Fermuse Formation Newfoundland, South Australia, Russia and Norway.
文摘An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes important to assess the stability of a soil-nailed system.In the present study,an investigation into the pullout behaviour of soil nail with circular discs along the shaft has been carried out by a threedimensional finite element analysis using Abaqus/Explicit routine.A total of 67 simulations have been performed to accurately predict the pullout behaviour of soil nail.The soil nail under study has circular discs along its shaft varying in numbers from 1 to 4.The pullout of this soil nail in a pullout test box has been simulated with a constant overburden pressure of 20 kPa acting on the nail.The pullout load edisplacement characteristics,stresses around soil nail and failure mechanism during pullout are studied.Variations of dimensionless factors such as normalised pullout load factor and bearing capacity factor have been obtained with different combinations of parameters in terms of relative disc spacing ratio,anchorage length ratio,embedment ratio,diameter ratio and displacement ratio.From the results of analyses,it is found that nail with more circular discs requires higher pullout load.There are critical relative disc spacing ratio and diameter ratio which significantly affect the pullout behaviour of nail.
基金Financial assistance from DST, New Delhi in form of a WOS-A project No. SR/OY/WOS-A/ES-20/ 2008
文摘Ediacaran discs from the Jodhpur Sandstone of the Marwar Supergroup, Rajasthan, exhibit a wide size ranging from a few millimetres to 75 cm in diameter. Exceptionally large size of the discs in these rocks represent the largest reported so far from any Ediacaran assemblage. Although, larger medu-soid discs have been reported from USA, they are from the middle Cambrian and even younger rocks. Presence of microbial mats and weed-like structures with well preserved hold fasts and horizontal rhizome-like structures in association with some of these large-sized discs support their animal affinity, which probably feed on this weed-like vegetations. This association also supports their benthic habitat. Unlike the general trend of sudden increase in size of organisms in Ediacaran period and further decrease in size during Cambrian, these discs continued increasing in size in Cambrian also.
文摘Objective: To assess the validity, responsiveness, and test-retest reliability of DISCs (Depression Intensity Scale Circles) as a simple screening tool for depression in patients with cognitive or communicative deficits following acquired brain injury. Design: Cohort analysis of consecutive patients entered into an integrated care pathway for screening and management of depression in the context of rehabilitation. Setting: Regional neurological rehabilitation service in the UK. Participants: 114 patients with complex disabilities caused by acquired brain injury (mean (SD) age, 42.8 (14.5) years). Main outcome measures: DISCs (a graphic rating scale depicting six circles with increasing proportion of dark shading), Numbered Graphic Rating Scale (NGRS), Yale single question (“Do you often feel sad or depressed”), Beck Depression Inventory-II (BDI-II), DSM-IV criteria for depression. Results: At initial assessment the DISCs correlated with total BDI-II scores (Spearman ρ= 0.66, P < 0.001), NGRS (ρ= 0.87, P < 0.001), and DSM-IV (ρ= 0.59, P < 0.001).A DISCs score≥2 identified depression (major or minor) according to DSM-IV criteria with 60%sensitivity, 87%specificity, 75%positive predictive value, and 77%negative predictive value. Test-retest reliability after 24 hours (n = 66) showed“excellent”.level of agreement (weighted κ= 0.84). In 45 patients who received intervention for depression, the DISCs showed a significant change in response to treatment (Wilcoxon; P < 0.001). Conclusions: DISCs had acceptable convergent validity, reliability, and responsiveness as a simple graded tool for screening and assessment of depression in patients with complex disabilities following acquired brain injury. It warrants further investigation in patients with more profound language and cognitive deficits for which it is primarily intended.
文摘Turbulence is a fundamentally interesting physical phenomenon which is of fundamental interest. Indeed, it is at the origin of several industrial applications, the control of energy in these industrial applications pass by the comprehension and the modelling of turbulent flows. Several factors are at the origin of turbulence in the complex flows, among these factors, we can quote the effect of wings in the rotating flows. The interest of this work is to model and to simulate numerically the effect of wings on the level of turbulence in the flow between two contra-rotating discs. We have fixed on these two discs eight wings uniformly distributed and we have varied the height of the wings to have eleven values from 0 to 18 mm by maintaining the same Reynolds number of rotation. The numerical tool is based on a statistical model in a point using the closing of the second order of the transport equations of the Reynolds stresses （Reynolds Stress Model： RSM）. We have modelled wings effect on the flow by a source term added to the equation tangential speed. The results of the numerical simulation showed that all the average and fluctuating variables are affected the value of the kinetic energy of turbulence as those of Reynolds stresses increase with the height of the wings.
文摘We extend the research of axisymmetric waves in accretion discs with three-dimensional structure to the case that vertical self-gravity of the discs is included. We derive and analyze the dispersion relation and solve the eigenfunctions numerically. The following results have been reached: vertical self-gravity expands the forbidden region of the wave propagation. As the influence of the vertical self-gravity increases, the group velocities of the waves get smaller and the vertical nodes of the wave shrink to the middle plane of the disc.
文摘Gonad development requires a coordinated soma-germline interaction that ensures renewal and differentiation of germline and somatic stem cells to ultimately produce mature gametes. The Drosophila tumour suppressor gene discs large （dig） encodes a septate junction protein functioning during epithelial polarization, asymmetric neuroblast division, and formation of neuromuscular junctions. Here, we report the role of dig in testis development and its critical function in somatic cyst cells （SCCs）. In these cells dig is primarily required for their survival and expansion, and contributes to spermatocyte cyst differentiation. Cell death primarily occurred in SCCs at the end of spermatogonial amplification at a time when Dig becomes restricted in wild-type （wt） testes to the distal somatic cells capping the growing spermatocyte cysts. RNAi depletion of dig transcripts in early SCCs fully prevented testis development, whereas depletion in late SCCs resulted in a breakdown of spermatocyte cyst structure and germ cell individualization. Specific dig expression in SCCs resulted in developmental rescue of dig mutant testes, whereas its expression in germ cells exerted no such effect, dig overexpression in wt testes led to spermatocyte cyst expansion at the expense of spermatogonial cysts. Our data demonstrate that dig is essentially required in SCCs for their survival, expansion, and differentiation, and for the encapsulation of the germline cells.
文摘We study the stability of accretion disc around magnetised stars. Starting from the equations of magnetohydrodynamics we derive equations for linearized perturbation of geometrically thin, optically thick axisymmetric accretion disc with an internal dynamo around magnetized stars. The structure and evolution of such discs are governed by an evolution equation for matter surface density ∑(R,T). Using the time-dependent equations for an accretion disc we do a linear stability analysis of our steady disc solutions in the presence of the magnetic field generated due to an internal dynamo.
文摘By solving analytically the various types of Lane-Emden equations with rotation, we have discovered two new coupled fundamental properties of rotating, self-gravitating, gaseous discs in equilibrium: isothermal discs must, on average, exhibit strict power-law density profiles in radius x on their equatorial planes of the form , where A and k-1 are the integration constants;and “flat” rotation curves precisely such as those observed in spiral galaxy discs. Polytropic discs must, on average, exhibit strict density profiles of the form , where n is the polytropic index;and “flat” rotation curves described by square roots of upper incomplete gamma functions. By “on average”, we mean that, irrespective of the chosen boundary conditions, the actual profiles must oscillate around and remain close to the strict mean profiles of the analytic singular equilibrium solutions. We call such singular solutions the “intrinsic” solutions of the differential equations because they are demanded by the second-order equations themselves with no regard to the Cauchy problem. The results are directly applicable to gaseous galaxy discs that have long been known to be isothermal and to protoplanetary discs during the extended isothermal and adiabatic phases of their evolution. In galactic gas dynamics, they have the potential to resolve the dark matter—modified gravity controversy in a sweeping manner, as they render both of these hypotheses unnecessary. In protoplanetary disc research, they provide observers with a powerful new probing tool, as they predict a clear and simple connection between the radial density profiles and the rotation curves of self-gravitating discs in their very early (pre-Class 0) phases of evolution.
基金supported by the National Natural Foundation of China (No.30970797)Shaanxi Science and Technology Plan Projects (No. 2008k09-1)
文摘The aim of the present study was to compare the relationship of morphologically defined non-bulging/herni-ated, bulging and herniated intervertebral lumbar discs with quantitative apparent diffusion coefficient （ADC）. Thirty-two healthy volunteers and 28 patients with back pain or sciatica were examined by MRI. All intervertebral lumbar discs from L1 to S1 were classified according to morphological abnormality and degenerated grades. The ADC values of nucleus pulposus （NP） were measured and recorded. The significant differences about mean ADC values of NP were found between non-bulging/herniated discs and bulging discs as well as herniated discs （P 0.05）, whereas there were no significant differences in ADC values between bulging and herniated discs （P 0.05）. Moreover, statistically significant relationship was found in the mean ADC values of NP between ＂non-bulging/herniated and non-degenerated discs＂ and ＂non-bulging/herniated degenerated discs＂ as well as herniated discs （P 0.05）. Linear regression analysis between ADC value and disc level revealed an inverse correlation （r = -0.18）. The ADC map of the NP is a potentially useful tool for the quantitative assessment of componential and molecular alterations accompanied with lumbar disc abnormalities.
文摘Leaf senescence is often caused by water deficit and the chimeric gene PSA612-1PT is an auto-regulated gene delaying leaf senescence. Using in vitro leaf discs culture system, the changes of contents of chlorophylls, carotenoids, soluble protein and thiobarbituric acid reactive substance （TBARS） and antioxidant enzymes activities were investigated during leaf senescence of PSA612-1PT modified gerbera induced by osmotic stress compared with the control plant （wild type）. Leaf discs were incubated in 20%, 40% （w/v） polyethylene glycol （PEG） 6 000 nutrient solution for 20 h under continuous light [ 130 μmol/（m^2·s）]. The results showed that the contents of chlorophylls, carotenoids and soluble protein were decreased by osmotic stress with the decrease being more pronounced at 40% PEG, but that, at the same PEG concentration the decrease in the transgenic plants was significantly lower than that in the control plant. The activities of superoxide dismutase （SOD）, catalases （CAT）, ascorbate peroxidase （APX）, guaiacol peroxidase （GPX） and dehydroascorbate reductase （DHAR） were stimulated by PEG treatment. However, the increases were higher in PSA612-IPT transgenic plants than in the control plants, particularly at 40% PEG treatment. Lipid peroxidation （TBARS content） was increased by PEG treatment with the increase being much lower in transgenic plant than in the control plant. It could be concluded that the increases in the activities ofantioxidant enzymes including SOD, CAT, APX, GPX and DHAR were responsible for the delay of leaf senescence induced by osmotic stress.
基金supported by the National Natural Science Foundation of China(Grant No.81401768,81301646)the Natural Science Foundation of Jiangsu Province(Grant No.BK20140289)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20123201120018)China Postdoctoral Science Foundation on the 53rd general program(Grant No.2013M531404)
文摘Objective: To assess the effects of axial vibrations on gene expression and lumbar intervertebral disc degeneration in vivo. Methods: A modified bipedal rat model was established using a brachial plexus rhizotomy approach to imitate human upright posture. The experimental animals were randomly divided into three groups: control, vertical vibration, and whole-body vibration. Gene expression in degeneration of the intervertebral discs was assessed by reverse transcription-quantitative polymerase chain reaction. Results: The expression of aggrecan, Col1α1, Col2α1, and decorin were shown to be up-regulated in 14-week-old rats in the vertical vibration and whole-body vibration groups, whereas biglycan and versican expression was down-regulated in 14-week-old rats of the two experimental groups. Furthermore, biglycan and versican expression levels were shown to be lower in the whole-body vibration group than in the vertical vibration group(P<0.05). Conclusions: This in-vivo study demonstrated that vibrations can influence the expression of anabolic genes. Furthermore, whole-body vibrations seem to have a greater effect in this regard than vertical vibrations. A new method is expected to relieve the low back pain of the patients through our research.
基金supported by a grant from the National High Technology Research and Development Program of China (Program 863) (No. 2006AA02A124)
文摘KLD-12 peptide with a sequence of AcN-KLDLKLDLKLDL-CNH2 was synthesized and its biocompatibility was assessed in animals. Rabbit MSCs were cultured in the hydrogel for 2 weeks. Live cells were counted by using Calcein-AM/P1 fluorescence staining. MTT was employed to assess the viability of MSCs cultured in KLD-12 peptide solution of 0.01%, 0.03%, and 0.05%. Hemolysis test, skin irritation test and implantation test were conducted to evaluate its biocompatibility with host tissues. Our results demonstrated that the MSCs in hydrogel grew well and maintained round shape. Cell survival rate was 92.15% （mean： 92.15%±1.17%） at the 7th day and there was no difference in survival rate between day 7 and day 14. Cell proliferation test showed that the A value of the KLD-12 solutions was not significantly different from that of control groups （complete culture media） （P〉0.05） at the 24th and 48th h. The hemolysis rate of KLD-12 solution was 0.112%. Skin irritation test showed that the skin injected with KLD-12 solution remained normal and the score of skin irritation was 0. The histological examination with HE staining exhibited that the skin layers were clear and there was no infiltration with neutrophilic granulocytes and lymphocytes. It is concluded that KLD-12 peptide hydrogel bad a good biocompatibility with host rabbit and MSCs, and KLD-12 pep- tide hydrogel can provide an appropriate microenvironment for MSCs.
