Ti_(2)AlNb-based alloy was joined in a continuous drive friction welding machine under different rotational rates(500,1000 and 1500 r/min).The microstructure and mechanical properties of the joints were investigated.I...Ti_(2)AlNb-based alloy was joined in a continuous drive friction welding machine under different rotational rates(500,1000 and 1500 r/min).The microstructure and mechanical properties of the joints were investigated.It is shown that the weld zone(WZ) is fully composed of recrystallized B2 phase,and the grain size decreases with increasing rotational rate.The thermo-mechanically affected zone(TMAZ) suffers severe deformation during welding,due to which most of original precipitation phase is dissolved and streamlines are present.In the heat affected zone(HAZ),only the fine O phase is dissolved.The as-welded joint produced using 1000 r/min has the best mechanical properties,whose strength and elongation are both close to those of the base metal,while the as-welded joint obtained using 500 r/min exhibits the worst mechanical properties.Post-weld annealing treatment annihilates the deformation microstructure and fine O phase precipitates in the joints,consequently improving the mechanical properties significantly.Decomposed α_(2) phase is a weakness for the mechanical performance of the joint since microcracks are apt to form in it in the tensile test.展开更多
In order to relieve the deficiency of the usual cubic Hermite spline curves,the quartic Hermite spline curves with shape parameters is further studied in this work. The interpolation error and estimator of the quartic...In order to relieve the deficiency of the usual cubic Hermite spline curves,the quartic Hermite spline curves with shape parameters is further studied in this work. The interpolation error and estimator of the quartic Hermite spline curves are given. And the characteristics of the quartic Hermite spline curves are discussed.The quartic Hermite spline curves not only have the same interpolation and continuity properties of the usual cubic Hermite spline curves, but also can achieve local or global shape adjustment and C;continuity by the shape parameters when the interpolation conditions are fixed.展开更多
A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tange...A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tangency and curvature, huge number of line segments, and short lengths of line segments. These disadvantages hinder the development of high speed machining. To smooth the linear tool path and improve machining efficiency of short line segments, this paper presents an optimal feed interpolator based on G^2 continuous Bézier curves for the linear tool path. First, the areas suitable for fitting are screened out based on the geometric characteristics of continuous short segments (CSSs). CSSs in every area are compressed and fitted into a G^2 Continuous Bézier curve by using the least square method. Then a series of cubic Bézier curves are generated. However, the junction between adjacent Bézier curves is only G^0 continuous. By adjusting the control points and inserting Bézier transition curves between adjacent Bézier curves, the G^2 continuous tool path is constructed. The fitting error is estimated by the second-order Taylor formula. Without iteration, the fitting algorithm can be implemented in real-time environment. Second, the optimal feed interpolator considering the comprehensive constraints (such as the chord error constraint, the maximum normal acceleration, servo capacity of each axis, etc.) is proposed. Simulation and experiment are conducted. The results shows that the proposed method can generate smooth path, decrease the amount of segments and reduce machining time for machining of linear tool path. The proposed research provides an effective method for high-speed machining of complex 2-D/3-D profiles described by short line segments.展开更多
The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount...The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/（m^3.min） and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.展开更多
＂Continuous＂ tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source ro...＂Continuous＂ tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source rocks and ＂＇continuous＂ tight gas reservoirs in the Xujiahe Formation of the middle- south transition region, Sichuan Basin. The source rocks of the Xul Member and reservoir rocks of the Xu2 Member are thick （Xul Member： 40 m, Xu2 Member： 120 m） and are distributed continuously in this study area. The results of drilled wells show that the widespread sandstone reservoirs of the Xu2 Member are charged with natural gas. Therefore, the natural gas reservoirs of the Xu2 Member in the middle-south transition region are ＂continuous＂ tight gas reservoirs. The accumulation of ＂continuous＂ tight gas reservoirs is controlled by an adequate driving force of the pressure differences between source rocks and reservoirs, which is demonstrated by a ＂one-dimensional＂ physical simulation experiment. In this simulation, the natural gas of＂continuous＂ tight gas reservoirs moves tbrward with no preferential petroleum migration pathways （PPMP）, and the natural gas saturation of＂continuous＂ tight gas reservoirs is higher than that of conventional reservoirs.展开更多
BACKGROUND Time in range(TIR),as a novel metric for glycemic control,has robust relevance with diabetic complications.Diabetic peripheral neuropathy(DPN)is characterized by sudomotor dysfunction.AIM To explore the rel...BACKGROUND Time in range(TIR),as a novel metric for glycemic control,has robust relevance with diabetic complications.Diabetic peripheral neuropathy(DPN)is characterized by sudomotor dysfunction.AIM To explore the relationship between TIR obtained from continuous glucose monitoring(CGM)and sudomotor function detected by SUDOSCAN in subjects with type 2 diabetes.METHODS The research enrolled 466 inpatients with type 2 diabetes.All subjects underwent 3-d CGM and SUDOSCAN.SUDOSCAN was assessed with electrochemical skin conductance in hands(HESC)and feet(FESC).Average feet ESC<60μS was defined as sudomotor dysfunction(+),otherwise it was sudomotor dysfunction(-).TIR refers to the percentage of time when blood glucose is between 3.9-10 mmol/L during 1 d period.RESULTS Among the enrolled subjects,135(28.97%)presented with sudomotor dysfunction.Patients with sudomotor dysfunction(+)showed a decreased level of TIR(P<0.001).Compared to the lowest tertile of TIR,the middle and the highest tertiles of TIR was associated with an obviously lower prevalence of sudomotor dysfunction(20.51%and 21.94%vs 44.52%)(P<0.001).In addition,with the increase of TIR,HESC and FESC increased(P<0.001).Regression analysis demonstrated that TIR was inversely and independently linked with the prevalence of sudomotor dysfunction after adjusting for confounding values(odds ratio=0.979,95%CI:0.971-0.987,P<0.001).CONCLUSION The tight glycemic control assessed by TIR is of vitally protective value for sudomotor dysfunction in type 2 diabetes mellitus.展开更多
Continuous thermo-mechanical processing (CTMP) of 6201 aluminum alloy was simulated on Gleeble-1500. The deformed specimens were analyzed by the observation of TEM and the measurement of hardness. It was shown that r...Continuous thermo-mechanical processing (CTMP) of 6201 aluminum alloy was simulated on Gleeble-1500. The deformed specimens were analyzed by the observation of TEM and the measurement of hardness. It was shown that rapid solid solution and aging treatment can be effectively combined in one procedure by the strain induced during CTMP. The deformation temperature is ranging from 540* C to 300* C, the hardness increases directly before the 6th pass followed by a slight drop, the amount of precipitates increases with the holding time after deformation. Uniformly distributed and stabilized Mg2Si precipitates, as well as dislocation substructure can be observed on deformed specimens which have been subsequently held at 300℃ for 60 seconds.展开更多
Incidence of defects in MoSi2 rods prepared by con- tinuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects....Incidence of defects in MoSi2 rods prepared by con- tinuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects. Cross-section observations indicated that the typical inner defects in sintered MoSi2 rods were large fissure cavity, multiple small holes and single small cavity, of which the characteristic ultrasonic reflection patterns have been experimentally established. Formation of the inner defects is attributed to the inhomogeneous feedstock moving behav- ior in die, which is aggravated with increasing viscosity of binder. Defect free MoSi2 rods were prepared successfully via con. tinuous extrusion by carefully controlling the viscosity of binder.展开更多
The horizontal continuous casting process,the initial step in TP2 copper tubular processing,directly determines the microstructure and properties of copper tubular.However,the process parameters of the continuous cast...The horizontal continuous casting process,the initial step in TP2 copper tubular processing,directly determines the microstructure and properties of copper tubular.However,the process parameters of the continuous casting characterize time variation,multiple disturbances and strong coupling.As a consequence,their influence on a casting billet is difficult to be determined.Due to the above issues,the common factor and special factor analysis of the factor analysis model were used in this study,and the casting experiment and billet metallographic experiment were carried out to diagnose and analyze the reason of the microstructure inhomogeneity.The multiple process parameters were studied and classified using common factor analysis,2 the cast billets with abnormal microstructures were identified by GT^(2) statistics,and the most important factors affecting the microstructural homogeneity were found by special factor analysis.The calculated and experimental results show that the principal parameters influencing the inhomogeneity of solidified microstructure are the primary inlet water pressure and the primary outlet water temperature.According to the consequence of the above investigation,the inhomogeneity of the copper billet microstructure can be effectively improved when the process parameters are controlled and adjusted.展开更多
Few studies have assessed the difference in adaptive changes of alcohol metabolism in the case of chronic alcohol consumption pertaining to the genetic polymorphism of aldehyde dehydrogenase 2 (ALDH2) in humans. To ev...Few studies have assessed the difference in adaptive changes of alcohol metabolism in the case of chronic alcohol consumption pertaining to the genetic polymorphism of aldehyde dehydrogenase 2 (ALDH2) in humans. To evaluate the influences of ALDH2 genotypes on changes in alcohol metabolism due to continuous alcohol intake, we conducted an intervention study by setting a continuous drinking period between two abstinence periods. The subjects in this study comprised 20 - 25-year-old males, including 15 males carrying ALDH2*1/*1 and 16 carrying ALDH2*1/*2 genotypes. Following the abstinence period of 4 weeks (from day 1 to day 28), all subjects drank commercially available beer (500 ml) every evening for 6 weeks (from day 30 to day 71) and subsequently abstained from drinking again for 4 weeks (from day 73 to day 100). The next morning, after the end of each period, drinking tests (DTs) were performed on each subject (DT1 on day 29, DT2 on day 72, and DT3 on day 101) to examine alcohol metabolism. The subjects drank shochu (a distilled alcoholic beverage), with an ethanol dose of 0.32 g/kg, within 20 minutes after overnight fasting. The alcohol elimination rate in subjects with ALDH2*1/*1 genotype was significantly higher during DT2 after the drinking period as compared with those at both DT1 and DT3 after the abstinence periods, whereas the elimination rate in subjects with ALDH2*1/*2 genotype did not change significantly during 3 DTs. However, blood acetaldehyde levels significantly decreased in subjects with both ALDH2 genotypes during DT2 as compared with those during DT1. The physiological subjective responses to alcohol also significantly decreased during DT2 in subjects with ALDH2*1/*2 genotype. Moreover, serum lipids, gamma-glutamyltransferase (GGT), and uric acid concentrations also varied between subjects with different ALDH2 genotypes due to continuous drinking. These results suggested that ALDH2 polymorphism modified adaptive changes in alcohol metabolism and physiological responses to continuous moderate alcohol consumption.展开更多
基金the financial supports from the Science and Technology Special Project, China (No. K19168)the National Science and Technology Major Project of China (No. 2017-VI-0004-0075)the National Natural Science Foundation of China (No. 52231002)。
文摘Ti_(2)AlNb-based alloy was joined in a continuous drive friction welding machine under different rotational rates(500,1000 and 1500 r/min).The microstructure and mechanical properties of the joints were investigated.It is shown that the weld zone(WZ) is fully composed of recrystallized B2 phase,and the grain size decreases with increasing rotational rate.The thermo-mechanically affected zone(TMAZ) suffers severe deformation during welding,due to which most of original precipitation phase is dissolved and streamlines are present.In the heat affected zone(HAZ),only the fine O phase is dissolved.The as-welded joint produced using 1000 r/min has the best mechanical properties,whose strength and elongation are both close to those of the base metal,while the as-welded joint obtained using 500 r/min exhibits the worst mechanical properties.Post-weld annealing treatment annihilates the deformation microstructure and fine O phase precipitates in the joints,consequently improving the mechanical properties significantly.Decomposed α_(2) phase is a weakness for the mechanical performance of the joint since microcracks are apt to form in it in the tensile test.
基金jointly supported by the National Natural Science Foundation of China(No.22273093,No.41905018,No.21903080)the Ministry of Science and Technology of China(No.2022YFF0606500)。
基金Hunan Provincial Natural Science Foundation(2017JJ3124)of Chinathe Scientific Research Fund(14B099)of Hunan Provincial Education Department of China
文摘In order to relieve the deficiency of the usual cubic Hermite spline curves,the quartic Hermite spline curves with shape parameters is further studied in this work. The interpolation error and estimator of the quartic Hermite spline curves are given. And the characteristics of the quartic Hermite spline curves are discussed.The quartic Hermite spline curves not only have the same interpolation and continuity properties of the usual cubic Hermite spline curves, but also can achieve local or global shape adjustment and C;continuity by the shape parameters when the interpolation conditions are fixed.
基金Supported by National Natural Science Foundation of China(Grant No.50875171)National Hi-tech Research and Development Program of China(863 Program,Grant No.2009AA04Z150)
文摘A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tangency and curvature, huge number of line segments, and short lengths of line segments. These disadvantages hinder the development of high speed machining. To smooth the linear tool path and improve machining efficiency of short line segments, this paper presents an optimal feed interpolator based on G^2 continuous Bézier curves for the linear tool path. First, the areas suitable for fitting are screened out based on the geometric characteristics of continuous short segments (CSSs). CSSs in every area are compressed and fitted into a G^2 Continuous Bézier curve by using the least square method. Then a series of cubic Bézier curves are generated. However, the junction between adjacent Bézier curves is only G^0 continuous. By adjusting the control points and inserting Bézier transition curves between adjacent Bézier curves, the G^2 continuous tool path is constructed. The fitting error is estimated by the second-order Taylor formula. Without iteration, the fitting algorithm can be implemented in real-time environment. Second, the optimal feed interpolator considering the comprehensive constraints (such as the chord error constraint, the maximum normal acceleration, servo capacity of each axis, etc.) is proposed. Simulation and experiment are conducted. The results shows that the proposed method can generate smooth path, decrease the amount of segments and reduce machining time for machining of linear tool path. The proposed research provides an effective method for high-speed machining of complex 2-D/3-D profiles described by short line segments.
基金Project supported by the Science Project of Harbin City(No. H2001-12)the Youth Foundation of School of Municipal and Environmental Engineering in Harbin Institute of Technology(No. 01306914).
文摘The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/（m^3.min） and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.
基金supported by the National Major Grant of"Accumulation Law,Key Technologies and Evaluations of the Stratigraphic Reservoirs"(No.2008ZX05000-001) from the Research Institute of Petroleum Exploration & Development,PetroChina
文摘＂Continuous＂ tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source rocks and ＂＇continuous＂ tight gas reservoirs in the Xujiahe Formation of the middle- south transition region, Sichuan Basin. The source rocks of the Xul Member and reservoir rocks of the Xu2 Member are thick （Xul Member： 40 m, Xu2 Member： 120 m） and are distributed continuously in this study area. The results of drilled wells show that the widespread sandstone reservoirs of the Xu2 Member are charged with natural gas. Therefore, the natural gas reservoirs of the Xu2 Member in the middle-south transition region are ＂continuous＂ tight gas reservoirs. The accumulation of ＂continuous＂ tight gas reservoirs is controlled by an adequate driving force of the pressure differences between source rocks and reservoirs, which is demonstrated by a ＂one-dimensional＂ physical simulation experiment. In this simulation, the natural gas of＂continuous＂ tight gas reservoirs moves tbrward with no preferential petroleum migration pathways （PPMP）, and the natural gas saturation of＂continuous＂ tight gas reservoirs is higher than that of conventional reservoirs.
基金National Natural Science Foundation of China,No.81774134 and No.81873174Natural Science Foundation of Jiangsu Province of China,No.BK20150558 and No.BK20171331+2 种基金Postdoctoral Foundation of Jiangsu Province of China,No.1501120CJiangsu Province 333 Talent Funding Project,No.BRA2017595Young Medical Key Talents Project of Jiangsu Province,No.QNRC2016902.
文摘BACKGROUND Time in range(TIR),as a novel metric for glycemic control,has robust relevance with diabetic complications.Diabetic peripheral neuropathy(DPN)is characterized by sudomotor dysfunction.AIM To explore the relationship between TIR obtained from continuous glucose monitoring(CGM)and sudomotor function detected by SUDOSCAN in subjects with type 2 diabetes.METHODS The research enrolled 466 inpatients with type 2 diabetes.All subjects underwent 3-d CGM and SUDOSCAN.SUDOSCAN was assessed with electrochemical skin conductance in hands(HESC)and feet(FESC).Average feet ESC<60μS was defined as sudomotor dysfunction(+),otherwise it was sudomotor dysfunction(-).TIR refers to the percentage of time when blood glucose is between 3.9-10 mmol/L during 1 d period.RESULTS Among the enrolled subjects,135(28.97%)presented with sudomotor dysfunction.Patients with sudomotor dysfunction(+)showed a decreased level of TIR(P<0.001).Compared to the lowest tertile of TIR,the middle and the highest tertiles of TIR was associated with an obviously lower prevalence of sudomotor dysfunction(20.51%and 21.94%vs 44.52%)(P<0.001).In addition,with the increase of TIR,HESC and FESC increased(P<0.001).Regression analysis demonstrated that TIR was inversely and independently linked with the prevalence of sudomotor dysfunction after adjusting for confounding values(odds ratio=0.979,95%CI:0.971-0.987,P<0.001).CONCLUSION The tight glycemic control assessed by TIR is of vitally protective value for sudomotor dysfunction in type 2 diabetes mellitus.
文摘Continuous thermo-mechanical processing (CTMP) of 6201 aluminum alloy was simulated on Gleeble-1500. The deformed specimens were analyzed by the observation of TEM and the measurement of hardness. It was shown that rapid solid solution and aging treatment can be effectively combined in one procedure by the strain induced during CTMP. The deformation temperature is ranging from 540* C to 300* C, the hardness increases directly before the 6th pass followed by a slight drop, the amount of precipitates increases with the holding time after deformation. Uniformly distributed and stabilized Mg2Si precipitates, as well as dislocation substructure can be observed on deformed specimens which have been subsequently held at 300℃ for 60 seconds.
文摘Incidence of defects in MoSi2 rods prepared by con- tinuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects. Cross-section observations indicated that the typical inner defects in sintered MoSi2 rods were large fissure cavity, multiple small holes and single small cavity, of which the characteristic ultrasonic reflection patterns have been experimentally established. Formation of the inner defects is attributed to the inhomogeneous feedstock moving behav- ior in die, which is aggravated with increasing viscosity of binder. Defect free MoSi2 rods were prepared successfully via con. tinuous extrusion by carefully controlling the viscosity of binder.
基金This work is financially supported by Basic Scientific Project of Liaoning Provincial Department of Education(LJKMZ20220591)Science and Technology Plan Project of Changzhou,China(CQ20220057).
文摘The horizontal continuous casting process,the initial step in TP2 copper tubular processing,directly determines the microstructure and properties of copper tubular.However,the process parameters of the continuous casting characterize time variation,multiple disturbances and strong coupling.As a consequence,their influence on a casting billet is difficult to be determined.Due to the above issues,the common factor and special factor analysis of the factor analysis model were used in this study,and the casting experiment and billet metallographic experiment were carried out to diagnose and analyze the reason of the microstructure inhomogeneity.The multiple process parameters were studied and classified using common factor analysis,2 the cast billets with abnormal microstructures were identified by GT^(2) statistics,and the most important factors affecting the microstructural homogeneity were found by special factor analysis.The calculated and experimental results show that the principal parameters influencing the inhomogeneity of solidified microstructure are the primary inlet water pressure and the primary outlet water temperature.According to the consequence of the above investigation,the inhomogeneity of the copper billet microstructure can be effectively improved when the process parameters are controlled and adjusted.
文摘Few studies have assessed the difference in adaptive changes of alcohol metabolism in the case of chronic alcohol consumption pertaining to the genetic polymorphism of aldehyde dehydrogenase 2 (ALDH2) in humans. To evaluate the influences of ALDH2 genotypes on changes in alcohol metabolism due to continuous alcohol intake, we conducted an intervention study by setting a continuous drinking period between two abstinence periods. The subjects in this study comprised 20 - 25-year-old males, including 15 males carrying ALDH2*1/*1 and 16 carrying ALDH2*1/*2 genotypes. Following the abstinence period of 4 weeks (from day 1 to day 28), all subjects drank commercially available beer (500 ml) every evening for 6 weeks (from day 30 to day 71) and subsequently abstained from drinking again for 4 weeks (from day 73 to day 100). The next morning, after the end of each period, drinking tests (DTs) were performed on each subject (DT1 on day 29, DT2 on day 72, and DT3 on day 101) to examine alcohol metabolism. The subjects drank shochu (a distilled alcoholic beverage), with an ethanol dose of 0.32 g/kg, within 20 minutes after overnight fasting. The alcohol elimination rate in subjects with ALDH2*1/*1 genotype was significantly higher during DT2 after the drinking period as compared with those at both DT1 and DT3 after the abstinence periods, whereas the elimination rate in subjects with ALDH2*1/*2 genotype did not change significantly during 3 DTs. However, blood acetaldehyde levels significantly decreased in subjects with both ALDH2 genotypes during DT2 as compared with those during DT1. The physiological subjective responses to alcohol also significantly decreased during DT2 in subjects with ALDH2*1/*2 genotype. Moreover, serum lipids, gamma-glutamyltransferase (GGT), and uric acid concentrations also varied between subjects with different ALDH2 genotypes due to continuous drinking. These results suggested that ALDH2 polymorphism modified adaptive changes in alcohol metabolism and physiological responses to continuous moderate alcohol consumption.
