An improved finite difference method （FDM）is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aero...An improved finite difference method （FDM）is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aerostatic bearings. A detailed theoretical analysis of the pressure distribution of the orifice-compensated aerostatic journal bearing is presented. The nonlinear dimensionless Reynolds equation of the aerostatic journal bearing is solved by the finite difference method. Based on the principle of flow equilibrium, a new iterative algorithm named the variable step size successive approximation method is presented to adjust the pressure at the orifice in the iterative process and enhance the efficiency and convergence performance of the algorithm. A general program is developed to analyze the pressure distribution of the aerostatic journal bearing by Matlab tool. The results show that the improved finite difference method is highly effective, reliable, stable, and convergent. Even when very thin gas film thicknesses （less than 2 Win）are considered, the improved calculation method still yields a result and converges fast.展开更多
AIM:To propose a novel glaucoma surgery for rebalancing translaminar pressure difference.METHODS:Three non-human primates with normal eyes and two with laser-induced glaucoma underwent the novel surgical procedure.Can...AIM:To propose a novel glaucoma surgery for rebalancing translaminar pressure difference.METHODS:Three non-human primates with normal eyes and two with laser-induced glaucoma underwent the novel surgical procedure.Cannulation of the subarachnoid space was performed after completion of routine vitrectomy steps.An XEN 45 implant was inserted into the created puncture to communicate between the vitreous body and subarachnoid space.Intraocular pressure(IOP),fundus photography,and spectral-domain optical coherence tomography were assessed at baseline and regular intervals during follow-up.RESULTS:All operated eyes showed IOP reduction in the first postoperative month.Two(2/3)normal eyes and one(1/2)glaucomatous eye maintained lower IOP until 18mo after operation.The XEN 45 implant remained positioned through the lamina cribrosa in all normal eyes but was not detected in two glaucomatous eyes.Complications observed in this study included retinal vascular bleeding in 1/3 normal eyes and XEN implant dislocation in all 2 glaucomatous eyes.CONCLUSION:Subarachnoid space cannulation and mini-shunt implantation may contribute to IOP reduction,possibly by rebalancing translaminar pressure difference and enhancing aqueous humor drainage.The development of a suitable mini-shunt requires further investigation.展开更多
The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence...The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence is still lacking.To validate this framework,here we employ a programmable robotic platform,where a single light-controlled wheeled robot travels in an activity landscape.Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force.This result unambiguously confirms the theoretical predictions,thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter.展开更多
Static ice pressure affects safe operation of hydraulic structures. However, current detection methods are hindered by the following limitations： poor real-time performance and errors owing to the partial pressure of...Static ice pressure affects safe operation of hydraulic structures. However, current detection methods are hindered by the following limitations： poor real-time performance and errors owing to the partial pressure of the surrounding wall on traditional electrical resistance strain bellow pressure sensors. We developed a fiber optic sensor with a special pressure bellow to monitor the static ice pressure on hydraulic structures and used the sensor to measure static pressure in laboratory ice growth and melting tests from -30℃ to 5℃. The sensor resolution is 0.02 kPa and its sensitivity is 2.74 × 10-4/kPa. The experiments suggest that the static ice pressure peaks twice during ice growth and melting. The first peak appears when the ice temperature drops to -15℃ owing to the liquid water to solid ice transition. The second peak appears at 0℃ owing to the thermal expansion of the ice during ice melting. The novel fiber optic sensor exhibits stable performance, high resolution, and high sensitivity and it can be used to monitor the static ice pressure during ice growth and melting.展开更多
The static dent resistance performance of the aluminum alloy double-curved panel formed using viscous pressure forming (VPF)was studied by finite element analysis,which mainly considers the forming process conditions....The static dent resistance performance of the aluminum alloy double-curved panel formed using viscous pressure forming (VPF)was studied by finite element analysis,which mainly considers the forming process conditions.The whole simulation consisting of three stages,i.e.,forming,spring-back and static dent resistance,was carried out continuously using the finite element code ANSYS.The influence of blank holder pressure(BHP)and the drawbead on the stiffness and the static dent resistance of the panels formed using VPF was analyzed.The results show that the adequate setting of the drawbead can increase the plastic deformation of the double-curved panel,which is beneficial to the initial stiffness and the static dent resistance.There is an optimum BHP range for the stiffness and the static dent resistance.展开更多
To address the control accuracy of large fuel flowrate during pressure fluctuation,a novel electro-hydraulic fuel metering unit(FMU)is constructed for afterburner fuel system of military aeroengine.Different from the ...To address the control accuracy of large fuel flowrate during pressure fluctuation,a novel electro-hydraulic fuel metering unit(FMU)is constructed for afterburner fuel system of military aeroengine.Different from the previous FMU,the proposed FMU can achieve the higher precision opening control by a new metering valve with double control chambers(MVDCC),and realize the lower pressure difference fluctuation regulating by a novel two-stage constant pressure difference compensated valve(CPDCV)with dynamic damping orifice and damping piston.The experimental and AMESim simulation results verify the validity and superiority of the novel FMU.Since the temperature-induced variation in fuel properties and device capabilities may degrade or even impair the properties of novel FMU,the discharge flowrate is analyzed by global sensitivity analysis to research the effect proportion of each factor,the temperature effect is explored to ensure the working reliability in long-span temperature variation.Finally,the optimization of structure parameters for novel CPDCV can further reduce pressure difference fluctuation during pressure regulation,and the overshoot,adjust time and the integral of time multiplied by absolute value of error(ITAE)can be reduced by 24%,30%and 26%,respectively.This paper provides a reference for improving the stability of large flowrate during pressure fluctuation.展开更多
Exact calculations of the static earth pressure from a thick alluvium require accurate/Co values. These calculations influence the sinking cost and the safety of the freezing method. The static earth pressure coeffici...Exact calculations of the static earth pressure from a thick alluvium require accurate/Co values. These calculations influence the sinking cost and the safety of the freezing method. The static earth pressure coefficient （K0） of thick and deep soil was analyzed using laboratory tests. The results show that the static earth pressure coefficient of thick and deep soils is nonlinear and different from that of superficial soils. The constant of superficial soils is usually invariant and the total stress or incremental stress definitions used in traditional geo-meehanics give the same value. The influence of load increments when calculating for superficial soil is ignored. The difference in values of K0 for thick alluvium defimed by the total stress or the incremental stress methods is over 10%. The effects of the thick alluvium on K0 should be considered during the design of frozen shaft projects. Such things as the frozen shaft thickness and the excavated section height should be chosen to assure the rationality of the design and to avoid potential faults and accidents.展开更多
The two-pass isothermal hot compression method was used to study the effect of different thermal deformation conditions on static recrystallization behavior in Ni-Cr-Mo series SA508Gr.4N low alloy steel with interval ...The two-pass isothermal hot compression method was used to study the effect of different thermal deformation conditions on static recrystallization behavior in Ni-Cr-Mo series SA508Gr.4N low alloy steel with interval holding time ranging from 1 to 300 s,temperature ranging from 950 to 1150℃,strain rate ranging from 0.01 to 1 s^(-1),true strains ranging from 0.1 to 0.2,and initial austenite grain size ranging from 175 to 552μm.It can be concluded that the static recrystallization volume fraction gradually increases with the increase in the deformation temperature,strain rate,strain and pass interval,and the decrease in the initial grain size,which is mainly due to the increase in the deformation energy storage and dislocations.Moreover,strain-induced grain boundary migration is the nucleation mechanism for static recrystallization of SA508Gr.4N low alloy steel.Based on the stress-strain curve,the predicted value obtained from the established static recrystallization kinetics model is in good consistence with the experimental value,and the static recrystallization thermal activation energy of SA508Gr.4N steel was calculated as 264,225.99 J/mol.展开更多
The static earth pressure coefficient of soils is,approximately,considered to be a constant in the view of clas-sical soil mechanics. This is supported by many research results. The high pressure experimental research...The static earth pressure coefficient of soils is,approximately,considered to be a constant in the view of clas-sical soil mechanics. This is supported by many research results. The high pressure experimental research and analysis of remolding deep soil described herein indicate that the static earth pressure of thick overburden has a notable non lin-ear characteristic. It also appears larger than that of superficial soils. It is necessary for deep coal mine design and con-struction to consider this particularity of soil pressure so as to avoid engineering accidents and heavy loss of life and property.展开更多
A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditiona...A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditional numerical method of the same equations corroborates well the reliability and rate of FEFDM.Moreover,a flow rate estimate method was developed for the project whose injection rate has not been clearly determined.A wellhead pressure regime determined by this method was successfully applied to the trial injection operations in Shihezi formation of Shenhua CCS Project,which is a good practice verification of FEFDM.At last,this method was used to evaluate the effect of friction and acceleration terms on the flow equation on the wellhead pressure.The result shows that for deep wellbore,the friction term can be omitted when flow rate is low and in a wide range of velocity the acceleration term can always be deleted.It is also shown that with flow rate increasing,the friction term can no longer be neglected.展开更多
Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gase...Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gases encountered in explosive blasting processes.Accurate measurement and deep understanding of the expansive properties of SCAs are important in their industrial application.An improved outer pipe method(OPM),termed the upper end surface method(UESM),is proposed in this paper to overcome the shortcomings of the OPM in the expansive pressure measurement of SCAs.Numerical simulation is used to proof the concept and a mathematical model established to relate the internal pressure and the radial strains at different positions in the upper end surface method test equipment.The new equipment is calibrated using oil pressure and strain measurements.The calibrated equipment is then used to measure the expansion pressure of SCA at three different water contents to proof its potential.The differences in the measurements with OPM and UESM at three different moisture contents are less than 4%.The experimental results confirm the accuracy and applicability of the more user friendly and less expensive UESM in the measurement of the expansive pressures of SCAs.展开更多
This study aims to develop a system and measurement method for investigating the static and dynamic pressure behavior of compression products. The self-designed measurement system, named "cloth-press" (LLY-5...This study aims to develop a system and measurement method for investigating the static and dynamic pressure behavior of compression products. The self-designed measurement system, named "cloth-press" (LLY-56B), is a direct measurement method, which is based on a rigid hemisphere with three pressure sensors distributed on its surface. The static pressure is measured at predetermined press depth, and the dynamic pressure is measured under the processing of fabric 3D deformation. The pressure distributions at the basic three sites are accepted as the measurement results. The measurement results provide much information in the field of compression fabric assessment, and the measurement system can be used in scientific research institutes and factories, contributing to optimize process parameters and quality control of compression garment.展开更多
Individual differences and coping skills have influential impacts on stress process by influencing the eventual outcomes of the stressors, contributing to either wellbeing, or illness and negative experiences. The aim...Individual differences and coping skills have influential impacts on stress process by influencing the eventual outcomes of the stressors, contributing to either wellbeing, or illness and negative experiences. The aim of this paper is to explore the individual differences and coping strategies of a cohort of women with health professionals’ occupational pressure. This is a cross-sectional survey, informed by the transactional model of stress and coping framework, and carried out on women health professionals (n = 203) from the Kuala Lumpur Hospital. Multiple regressions were conducted to examine the potential moderators of stress. Women Health Professionals reported stress with six out of eight organizational sources of pressure, with relationship being a key stressor. Their individual differences (mean + SD) were characterised by low drive (7.6 + 1.9-8.2 + 2.0), low personal influence (10.8 + 2.0 to 11.7 + 2.3), moderate control (13.4 + 3.4 to 16.3 + 2.4), and high impatience behaviour (19.1 + 3.8 to 20.4 + 3.3). With Coping strategy, the Life-work-balance coping is a significant positive predictor for five out of the nine outcomes of occupational pressure [state of mind (p ress management guideline to ameliorate stress amongst those vulnerable workers. Future studies to examine individual differences of these female-dominated professions across health setting are needed to better inform the pressure-at-work issues for the increasing Asian women health professionals.展开更多
To analyze static pressure between back plate and cylinder in an A186 carding machine,a fluid model is established. The model takes into account static pressure of airflow near back plate with the numerical simulation...To analyze static pressure between back plate and cylinder in an A186 carding machine,a fluid model is established. The model takes into account static pressure of airflow near back plate with the numerical simulation method of Computational Fluid Dynamics (CFD) in FLUENT software. The result of the simulation in the model shows that static pressure in this area quickly increases to its maximum then rapidly decreases to a lower fixed value from inlet to outlet along a zone between back plate and cylinder. Both rotating speeds of the cylinder and the taker-in affect static pressure from the inlet to the outlet,of which the cylinder rotating speed has more influence than that of taker-in. Numerical simulations reveal that static pressure on surface of back plate are in good agreement with the former result of experimental analysis.展开更多
BACKGROUND Hemodialysis machine-generated circuit pressures and clearance profiles are potential predictors of quality assurances. In our practice, we previously we observed that elevated static access pressures were ...BACKGROUND Hemodialysis machine-generated circuit pressures and clearance profiles are potential predictors of quality assurances. In our practice, we previously we observed that elevated static access pressures were associated with abnormal Kt/V values, high access recirculation and deviation of the Kt/V profile (Abnormal Kt/V profile) from normally expected values (Normal Kt/V profile). AIM To hypothesize that static or derived access pressures would correlate with direct intra-access blood flow rates and that clearance (Kt/V) profiles would correlate with measured Kt/V values. METHODS Static access pressures, real-time adequacy of dialysis and intra-access blood flow were investigated in end stage renal disease patients undergoing hemodialysis. Wilcoxon-Mann-Whitney test, chi-square test or Fisher’s exact test was used to investigate differences between the groups;Spearman’s rank correlation test to investigate relationships between static pressures, direct intra-access pressures and Kt/V profiles;and multinomial logistic regression models to identify the independent effect of selected variables on Kt/V profiles. Odds ratio were calculated to measure the association between the variables and Kt/V profiles. RESULTS One hundred and seven patients were included for analysis. There were no significant differences between genders, and types of vascular access between the normal vs. abnormal clearance (Kt/V) profile groups. No significant correlation could be demonstrated between static access pressures and Kt/V profiles, static access pressures and intra-access blood flow, intra-access blood flow and Kt/V profiles, measured Kt/V and Kt/V profiles or recirculation and Kt/V profiles. CONCLUSION In this study utilizing measured versus estimated data, we could not validate that dialysis machine generated elevated static pressures predict intra-access blood flow disturbances or that abnormal Kt/V profiles predict access recirculation or inadequate dialysis. These parameters, though useful estimates, cannot be accepted as quality assurance for dialysis adequacy or access function without further evidences.展开更多
Effects of temperature and pressure differences on water seepage in breccia were investigated by using the physicochemical seepage instrument.The results show that the relationship of flow and pressure differences can...Effects of temperature and pressure differences on water seepage in breccia were investigated by using the physicochemical seepage instrument.The results show that the relationship of flow and pressure differences can be expressed by a linear equation,and the seepage coefficient is linearly correlated with temperature.The relation-ship between seepage flow and temperature could be described with the linear equation.The constant and tempera-ture seepage coefficient showed a linear relation with pressure.Binary quantitative equation for the seepage flow,temperature and pressure was obtained,and explained with experimental data and theoretical analysis.展开更多
To explore the static pressure dynamic disaster mechanism of coal-and-gas outburst(CGO)fluid,the self-developed multifield coupling large-scale physical simulation test system of coal mine dynamic disaster was used to...To explore the static pressure dynamic disaster mechanism of coal-and-gas outburst(CGO)fluid,the self-developed multifield coupling large-scale physical simulation test system of coal mine dynamic disaster was used to carry out gas outburst and CGO physical simulation tests in straight,L-shaped and T-shaped roadways.The influence of roadway shape on the evolution of static pressure was explored,and the role of pulverized coal in the process of static pressure dynamic disaster was clarified.The results indicated that the static pressure showed a fluctuating downward trend during the outburst process.When gas outburst,the middle and front parts of the roadway in the straight section roadway were the most serious areas of static pressure disasters in the three shapes of roadways.The duration and range of high static pressure disaster in L-shaped roadway were larger than those in T-shaped and straight roadways in turn.When CGO,the most serious area of static pressure disaster in L-shaped and T-shaped roadways moved backward to the middle of the straight section roadway,and there was a rebound phenomenon in the process of static pressure fluctuation decline,which showed the pulse characteristics of CGO.During the outburst,the static pressure dynamic disaster hazard of L-shaped roadway was higher than that of T-shaped roadway,and the static pressure at the bifurcation structure decayed faster than that at the turning structure,which indicated that T-shaped roadway was more conducive to the release of static pressure in roadway,thus reduced the risk of static pressure disaster.When gas outburst,the static pressure attenuation of the fuid in the roadway before and after the turning and bifurcation structure was greater than that of CGO.The peak static pressure and impulse of the fluid during gas outburst were 2 times and 4-5 times that of CGO respectively.The presence of pulverized coal reduced the attenuation of static pressure and the hazard of dynamic disaster,prolonged the release time of energy,and led to the change of the maximum static pressure disaster area.展开更多
The development of urbanization has led to an increase in the number and scale of construction projects and the types of building construction engineering are getting advance and diverse due to the rapid development o...The development of urbanization has led to an increase in the number and scale of construction projects and the types of building construction engineering are getting advance and diverse due to the rapid development of technology.One of them is the static pressure prestressed pipe pile which is the most commonly used technology in modern building construction work.It is mainly used for pile foundation in construction work,and it has the advantages in less pollution,low noise,and high efficiency compared to the traditional pile foundation.Study on the characteristics of static pressure prestressed pipe pile must be carried out and strengthened the research to increase the effectiveness and quality of static pressure prestressed pipe pile on construction works.This paper is mainly to analyzed the characteristic and construction technology of static pressure prestressed pipe piles on building construction work.展开更多
1 INTRODUCTIONUse of static mixers to process non-Newtonian fluids is quite commn.Data on thepressure drop of non-Newtonian fluids in Kenics static mixers are very useful in thedesign and engineering application of su...1 INTRODUCTIONUse of static mixers to process non-Newtonian fluids is quite commn.Data on thepressure drop of non-Newtonian fluids in Kenics static mixers are very useful in thedesign and engineering application of such mixers.However,only a few studies con-cerned with the pressure drop of non-Newtonian fluid flow in static ndxers can befound in literature.Wilkinson and Cliff presented pressure drop data for aqueousglycerine solutions(Newtonian fluids)and aqueous 1% polyacrylamide solution showingviscoelastic behavior.They found no difference between the friction factors of展开更多
基金The National Natural Science Foundation of China(No50475073,50775036)the High Technology Research Program of Jiangsu Province(NoBG2006035)
文摘An improved finite difference method （FDM）is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aerostatic bearings. A detailed theoretical analysis of the pressure distribution of the orifice-compensated aerostatic journal bearing is presented. The nonlinear dimensionless Reynolds equation of the aerostatic journal bearing is solved by the finite difference method. Based on the principle of flow equilibrium, a new iterative algorithm named the variable step size successive approximation method is presented to adjust the pressure at the orifice in the iterative process and enhance the efficiency and convergence performance of the algorithm. A general program is developed to analyze the pressure distribution of the aerostatic journal bearing by Matlab tool. The results show that the improved finite difference method is highly effective, reliable, stable, and convergent. Even when very thin gas film thicknesses （less than 2 Win）are considered, the improved calculation method still yields a result and converges fast.
文摘AIM:To propose a novel glaucoma surgery for rebalancing translaminar pressure difference.METHODS:Three non-human primates with normal eyes and two with laser-induced glaucoma underwent the novel surgical procedure.Cannulation of the subarachnoid space was performed after completion of routine vitrectomy steps.An XEN 45 implant was inserted into the created puncture to communicate between the vitreous body and subarachnoid space.Intraocular pressure(IOP),fundus photography,and spectral-domain optical coherence tomography were assessed at baseline and regular intervals during follow-up.RESULTS:All operated eyes showed IOP reduction in the first postoperative month.Two(2/3)normal eyes and one(1/2)glaucomatous eye maintained lower IOP until 18mo after operation.The XEN 45 implant remained positioned through the lamina cribrosa in all normal eyes but was not detected in two glaucomatous eyes.Complications observed in this study included retinal vascular bleeding in 1/3 normal eyes and XEN implant dislocation in all 2 glaucomatous eyes.CONCLUSION:Subarachnoid space cannulation and mini-shunt implantation may contribute to IOP reduction,possibly by rebalancing translaminar pressure difference and enhancing aqueous humor drainage.The development of a suitable mini-shunt requires further investigation.
基金supported by the National Natural Science Foundation of China (Grant Nos.T2325027,12274448,T2350007,12404239,12174041,12325405,12090054,and T2221001)the National Key R&D Program of China (Grant No.2022YFF0503504)。
文摘The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence is still lacking.To validate this framework,here we employ a programmable robotic platform,where a single light-controlled wheeled robot travels in an activity landscape.Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force.This result unambiguously confirms the theoretical predictions,thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter.
基金supported by the National Natural Science Foundation of China(No.51279122)the Graduate Innovation Foundation of Taiyuan University of Technology(No.2013A019)
文摘Static ice pressure affects safe operation of hydraulic structures. However, current detection methods are hindered by the following limitations： poor real-time performance and errors owing to the partial pressure of the surrounding wall on traditional electrical resistance strain bellow pressure sensors. We developed a fiber optic sensor with a special pressure bellow to monitor the static ice pressure on hydraulic structures and used the sensor to measure static pressure in laboratory ice growth and melting tests from -30℃ to 5℃. The sensor resolution is 0.02 kPa and its sensitivity is 2.74 × 10-4/kPa. The experiments suggest that the static ice pressure peaks twice during ice growth and melting. The first peak appears when the ice temperature drops to -15℃ owing to the liquid water to solid ice transition. The second peak appears at 0℃ owing to the thermal expansion of the ice during ice melting. The novel fiber optic sensor exhibits stable performance, high resolution, and high sensitivity and it can be used to monitor the static ice pressure during ice growth and melting.
文摘The static dent resistance performance of the aluminum alloy double-curved panel formed using viscous pressure forming (VPF)was studied by finite element analysis,which mainly considers the forming process conditions.The whole simulation consisting of three stages,i.e.,forming,spring-back and static dent resistance,was carried out continuously using the finite element code ANSYS.The influence of blank holder pressure(BHP)and the drawbead on the stiffness and the static dent resistance of the panels formed using VPF was analyzed.The results show that the adequate setting of the drawbead can increase the plastic deformation of the double-curved panel,which is beneficial to the initial stiffness and the static dent resistance.There is an optimum BHP range for the stiffness and the static dent resistance.
基金co-supported by the National Key Basic Research Program of China(No.2014CB046403)the National Science and Technology Major Project(2017-V-0015-0067)。
文摘To address the control accuracy of large fuel flowrate during pressure fluctuation,a novel electro-hydraulic fuel metering unit(FMU)is constructed for afterburner fuel system of military aeroengine.Different from the previous FMU,the proposed FMU can achieve the higher precision opening control by a new metering valve with double control chambers(MVDCC),and realize the lower pressure difference fluctuation regulating by a novel two-stage constant pressure difference compensated valve(CPDCV)with dynamic damping orifice and damping piston.The experimental and AMESim simulation results verify the validity and superiority of the novel FMU.Since the temperature-induced variation in fuel properties and device capabilities may degrade or even impair the properties of novel FMU,the discharge flowrate is analyzed by global sensitivity analysis to research the effect proportion of each factor,the temperature effect is explored to ensure the working reliability in long-span temperature variation.Finally,the optimization of structure parameters for novel CPDCV can further reduce pressure difference fluctuation during pressure regulation,and the overshoot,adjust time and the integral of time multiplied by absolute value of error(ITAE)can be reduced by 24%,30%and 26%,respectively.This paper provides a reference for improving the stability of large flowrate during pressure fluctuation.
基金Project BK2007040 supported by the Provincial Natural Science Foundation of Jiangsu, China
文摘Exact calculations of the static earth pressure from a thick alluvium require accurate/Co values. These calculations influence the sinking cost and the safety of the freezing method. The static earth pressure coefficient （K0） of thick and deep soil was analyzed using laboratory tests. The results show that the static earth pressure coefficient of thick and deep soils is nonlinear and different from that of superficial soils. The constant of superficial soils is usually invariant and the total stress or incremental stress definitions used in traditional geo-meehanics give the same value. The influence of load increments when calculating for superficial soil is ignored. The difference in values of K0 for thick alluvium defimed by the total stress or the incremental stress methods is over 10%. The effects of the thick alluvium on K0 should be considered during the design of frozen shaft projects. Such things as the frozen shaft thickness and the excavated section height should be chosen to assure the rationality of the design and to avoid potential faults and accidents.
基金This work was financially supported by the National Energy Application Technology Research and Engineering Demonstrative Project of China(NY201501)the National High Technology Research and Development Program of China(863 program.No.2012AA03A501)the National Key Research and Development Program of China(2016YFB0300203).
文摘The two-pass isothermal hot compression method was used to study the effect of different thermal deformation conditions on static recrystallization behavior in Ni-Cr-Mo series SA508Gr.4N low alloy steel with interval holding time ranging from 1 to 300 s,temperature ranging from 950 to 1150℃,strain rate ranging from 0.01 to 1 s^(-1),true strains ranging from 0.1 to 0.2,and initial austenite grain size ranging from 175 to 552μm.It can be concluded that the static recrystallization volume fraction gradually increases with the increase in the deformation temperature,strain rate,strain and pass interval,and the decrease in the initial grain size,which is mainly due to the increase in the deformation energy storage and dislocations.Moreover,strain-induced grain boundary migration is the nucleation mechanism for static recrystallization of SA508Gr.4N low alloy steel.Based on the stress-strain curve,the predicted value obtained from the established static recrystallization kinetics model is in good consistence with the experimental value,and the static recrystallization thermal activation energy of SA508Gr.4N steel was calculated as 264,225.99 J/mol.
基金Project 50534040 supported by the National Natrual Science Foundation of China
文摘The static earth pressure coefficient of soils is,approximately,considered to be a constant in the view of clas-sical soil mechanics. This is supported by many research results. The high pressure experimental research and analysis of remolding deep soil described herein indicate that the static earth pressure of thick overburden has a notable non lin-ear characteristic. It also appears larger than that of superficial soils. It is necessary for deep coal mine design and con-struction to consider this particularity of soil pressure so as to avoid engineering accidents and heavy loss of life and property.
基金Project(Z110803)supported by the State Key Laboratory of Geomechanics and Geotechnical Engineering,ChinaProject(2008AA062303)supported by the National High Technology Research and Development Program of China
文摘A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditional numerical method of the same equations corroborates well the reliability and rate of FEFDM.Moreover,a flow rate estimate method was developed for the project whose injection rate has not been clearly determined.A wellhead pressure regime determined by this method was successfully applied to the trial injection operations in Shihezi formation of Shenhua CCS Project,which is a good practice verification of FEFDM.At last,this method was used to evaluate the effect of friction and acceleration terms on the flow equation on the wellhead pressure.The result shows that for deep wellbore,the friction term can be omitted when flow rate is low and in a wide range of velocity the acceleration term can always be deleted.It is also shown that with flow rate increasing,the friction term can no longer be neglected.
基金funded by the State Key Research Development Program of China(No.2018YFC0604400)the National Science Foundation of China(Nos.51874068,52074062)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.N2001003,N160107001,N180701016,N182608003,N2001001)the 111 Project(No.B17009)The authors also acknowledge Nazarbayev University for funding the research through its Collaborative Research Program(No.OPCRP2020014).
文摘Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gases encountered in explosive blasting processes.Accurate measurement and deep understanding of the expansive properties of SCAs are important in their industrial application.An improved outer pipe method(OPM),termed the upper end surface method(UESM),is proposed in this paper to overcome the shortcomings of the OPM in the expansive pressure measurement of SCAs.Numerical simulation is used to proof the concept and a mathematical model established to relate the internal pressure and the radial strains at different positions in the upper end surface method test equipment.The new equipment is calibrated using oil pressure and strain measurements.The calibrated equipment is then used to measure the expansion pressure of SCA at three different water contents to proof its potential.The differences in the measurements with OPM and UESM at three different moisture contents are less than 4%.The experimental results confirm the accuracy and applicability of the more user friendly and less expensive UESM in the measurement of the expansive pressures of SCAs.
文摘This study aims to develop a system and measurement method for investigating the static and dynamic pressure behavior of compression products. The self-designed measurement system, named "cloth-press" (LLY-56B), is a direct measurement method, which is based on a rigid hemisphere with three pressure sensors distributed on its surface. The static pressure is measured at predetermined press depth, and the dynamic pressure is measured under the processing of fabric 3D deformation. The pressure distributions at the basic three sites are accepted as the measurement results. The measurement results provide much information in the field of compression fabric assessment, and the measurement system can be used in scientific research institutes and factories, contributing to optimize process parameters and quality control of compression garment.
文摘Individual differences and coping skills have influential impacts on stress process by influencing the eventual outcomes of the stressors, contributing to either wellbeing, or illness and negative experiences. The aim of this paper is to explore the individual differences and coping strategies of a cohort of women with health professionals’ occupational pressure. This is a cross-sectional survey, informed by the transactional model of stress and coping framework, and carried out on women health professionals (n = 203) from the Kuala Lumpur Hospital. Multiple regressions were conducted to examine the potential moderators of stress. Women Health Professionals reported stress with six out of eight organizational sources of pressure, with relationship being a key stressor. Their individual differences (mean + SD) were characterised by low drive (7.6 + 1.9-8.2 + 2.0), low personal influence (10.8 + 2.0 to 11.7 + 2.3), moderate control (13.4 + 3.4 to 16.3 + 2.4), and high impatience behaviour (19.1 + 3.8 to 20.4 + 3.3). With Coping strategy, the Life-work-balance coping is a significant positive predictor for five out of the nine outcomes of occupational pressure [state of mind (p ress management guideline to ameliorate stress amongst those vulnerable workers. Future studies to examine individual differences of these female-dominated professions across health setting are needed to better inform the pressure-at-work issues for the increasing Asian women health professionals.
基金Project of Liaoning Provincial Science and Technology Department, China(No.200322026)
文摘To analyze static pressure between back plate and cylinder in an A186 carding machine,a fluid model is established. The model takes into account static pressure of airflow near back plate with the numerical simulation method of Computational Fluid Dynamics (CFD) in FLUENT software. The result of the simulation in the model shows that static pressure in this area quickly increases to its maximum then rapidly decreases to a lower fixed value from inlet to outlet along a zone between back plate and cylinder. Both rotating speeds of the cylinder and the taker-in affect static pressure from the inlet to the outlet,of which the cylinder rotating speed has more influence than that of taker-in. Numerical simulations reveal that static pressure on surface of back plate are in good agreement with the former result of experimental analysis.
基金the Gatorade Trust through funds distributed by the University of Florida,Division of Nephrology,Hypertension,and Renal Transplantation,Gainesville,FL [Awarded to Abhilash Koratala(Principal investigator)Abutaleb A Ejaz(Mentor)]
文摘BACKGROUND Hemodialysis machine-generated circuit pressures and clearance profiles are potential predictors of quality assurances. In our practice, we previously we observed that elevated static access pressures were associated with abnormal Kt/V values, high access recirculation and deviation of the Kt/V profile (Abnormal Kt/V profile) from normally expected values (Normal Kt/V profile). AIM To hypothesize that static or derived access pressures would correlate with direct intra-access blood flow rates and that clearance (Kt/V) profiles would correlate with measured Kt/V values. METHODS Static access pressures, real-time adequacy of dialysis and intra-access blood flow were investigated in end stage renal disease patients undergoing hemodialysis. Wilcoxon-Mann-Whitney test, chi-square test or Fisher’s exact test was used to investigate differences between the groups;Spearman’s rank correlation test to investigate relationships between static pressures, direct intra-access pressures and Kt/V profiles;and multinomial logistic regression models to identify the independent effect of selected variables on Kt/V profiles. Odds ratio were calculated to measure the association between the variables and Kt/V profiles. RESULTS One hundred and seven patients were included for analysis. There were no significant differences between genders, and types of vascular access between the normal vs. abnormal clearance (Kt/V) profile groups. No significant correlation could be demonstrated between static access pressures and Kt/V profiles, static access pressures and intra-access blood flow, intra-access blood flow and Kt/V profiles, measured Kt/V and Kt/V profiles or recirculation and Kt/V profiles. CONCLUSION In this study utilizing measured versus estimated data, we could not validate that dialysis machine generated elevated static pressures predict intra-access blood flow disturbances or that abnormal Kt/V profiles predict access recirculation or inadequate dialysis. These parameters, though useful estimates, cannot be accepted as quality assurance for dialysis adequacy or access function without further evidences.
文摘Effects of temperature and pressure differences on water seepage in breccia were investigated by using the physicochemical seepage instrument.The results show that the relationship of flow and pressure differences can be expressed by a linear equation,and the seepage coefficient is linearly correlated with temperature.The relation-ship between seepage flow and temperature could be described with the linear equation.The constant and tempera-ture seepage coefficient showed a linear relation with pressure.Binary quantitative equation for the seepage flow,temperature and pressure was obtained,and explained with experimental data and theoretical analysis.
基金supported by the National Natural Science Foundation of China(51874055,52074047).
文摘To explore the static pressure dynamic disaster mechanism of coal-and-gas outburst(CGO)fluid,the self-developed multifield coupling large-scale physical simulation test system of coal mine dynamic disaster was used to carry out gas outburst and CGO physical simulation tests in straight,L-shaped and T-shaped roadways.The influence of roadway shape on the evolution of static pressure was explored,and the role of pulverized coal in the process of static pressure dynamic disaster was clarified.The results indicated that the static pressure showed a fluctuating downward trend during the outburst process.When gas outburst,the middle and front parts of the roadway in the straight section roadway were the most serious areas of static pressure disasters in the three shapes of roadways.The duration and range of high static pressure disaster in L-shaped roadway were larger than those in T-shaped and straight roadways in turn.When CGO,the most serious area of static pressure disaster in L-shaped and T-shaped roadways moved backward to the middle of the straight section roadway,and there was a rebound phenomenon in the process of static pressure fluctuation decline,which showed the pulse characteristics of CGO.During the outburst,the static pressure dynamic disaster hazard of L-shaped roadway was higher than that of T-shaped roadway,and the static pressure at the bifurcation structure decayed faster than that at the turning structure,which indicated that T-shaped roadway was more conducive to the release of static pressure in roadway,thus reduced the risk of static pressure disaster.When gas outburst,the static pressure attenuation of the fuid in the roadway before and after the turning and bifurcation structure was greater than that of CGO.The peak static pressure and impulse of the fluid during gas outburst were 2 times and 4-5 times that of CGO respectively.The presence of pulverized coal reduced the attenuation of static pressure and the hazard of dynamic disaster,prolonged the release time of energy,and led to the change of the maximum static pressure disaster area.
文摘The development of urbanization has led to an increase in the number and scale of construction projects and the types of building construction engineering are getting advance and diverse due to the rapid development of technology.One of them is the static pressure prestressed pipe pile which is the most commonly used technology in modern building construction work.It is mainly used for pile foundation in construction work,and it has the advantages in less pollution,low noise,and high efficiency compared to the traditional pile foundation.Study on the characteristics of static pressure prestressed pipe pile must be carried out and strengthened the research to increase the effectiveness and quality of static pressure prestressed pipe pile on construction works.This paper is mainly to analyzed the characteristic and construction technology of static pressure prestressed pipe piles on building construction work.
文摘1 INTRODUCTIONUse of static mixers to process non-Newtonian fluids is quite commn.Data on thepressure drop of non-Newtonian fluids in Kenics static mixers are very useful in thedesign and engineering application of such mixers.However,only a few studies con-cerned with the pressure drop of non-Newtonian fluid flow in static ndxers can befound in literature.Wilkinson and Cliff presented pressure drop data for aqueousglycerine solutions(Newtonian fluids)and aqueous 1% polyacrylamide solution showingviscoelastic behavior.They found no difference between the friction factors of
