The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the t...The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical T1G backing welding is investigated. The results show that the workpiece experiences double-peak thermal cycle in double-sided asymmetrical TIG backing welding. On the one hand, the fore arc has the pre- heating effect on the rear pass, and the pre-heating temperature depends on the distance between the double arcs, the heat input of fore arc, and the initial temperature of workpiece. On the other hand, the rear arc has the post-heating effect on the fore pass. The mutual effects of two heat sources decrease with the increase of arc distance.展开更多
Double main phase process is applied to fabricate [(Pr, Nd)1 – xMMx]13.8FebalM1.5B5.9 (x = 0.5 and 0.7;M = Cu, Al, Co, and Nb) sintered magnets with high misch metal (MM) content. In comparison to the magnets by sing...Double main phase process is applied to fabricate [(Pr, Nd)1 – xMMx]13.8FebalM1.5B5.9 (x = 0.5 and 0.7;M = Cu, Al, Co, and Nb) sintered magnets with high misch metal (MM) content. In comparison to the magnets by single main phase process, the enhanced magnetic properties have been achieved. For magnets of x = 0.7, Hcj increases to 371.9 kA/m by 60.5%, and (BH)max is significantly enhanced to 253.3 kJ/m3 by 56.9%, compared with those of the single main phase magnets of the same nominal composition. In combination with minor loops and magnetic recoil curves, the property improvement of magnets with double main phase method is well explained. As a result, it is demonstrated that double main phase technology is an effective approach to improve the permanent magnetic properties of MM based sintered magnets.展开更多
Nonylphenol(NP)residues,as a typical endocrine disrupting chemical(EDC),frequently exist in sewage,surface water,groundwater and even drinking water,which poses a serious threat to human health due to its bioaccumulat...Nonylphenol(NP)residues,as a typical endocrine disrupting chemical(EDC),frequently exist in sewage,surface water,groundwater and even drinking water,which poses a serious threat to human health due to its bioaccumulation.In order to remove NP,a series of MIL-100(Fe)/Zn Fe_(2)O_(4)/flake-like porous carbon nitride(MIL/ZC)was synthesized through in-situ synthesis at room temperature.High performance of ternary MIL/ZC is used to degrade NP under visible light irradiation.The results show that 30MIL/ZC2(20 wt.%Zn Fe_(2)O_(4))ternary composite had the best photocatalytic activity(99.84%)when the dosage was 30 mg.Further mechanism analysis shows that the excellent photocatalytic activity of 30MIL/ZC2could be ascribed to the double charge transfer process between flake-like porous carbon nitride(PCN)and other catalysts in the ternary heterojunction,and the separation of photogenerated electron-hole pairs was more effective.In addition,the 30MIL/ZC2 also showed high stability after five cycles of the photodegradation reaction.Furthermore,the active substance(·O_(2)^(-))was considered to be the main active substance in the NP degradation process.Based on the research results,the possible photocatalytic reaction mechanism of 30MIL/ZC2ternary composite was proposed and discussed in detail.展开更多
The authors consider a compound Cox model of insurance risk with the additional economic assumption of a positive interest rate. As the authors note a duality result relating a compound Cox model of insurance risk wit...The authors consider a compound Cox model of insurance risk with the additional economic assumption of a positive interest rate. As the authors note a duality result relating a compound Cox model of insurance risk with a positive interest rate and a double shot noise process, the authors analyze a double shot noise process systematically for its theoretical distributional properties, based on the piecewise deterministic Markov process theory, and the martingale methodology. The authors also obtain the moments of aggregate accumulated/discounted claims where the claim arrival process follows a Cox process with shot noise intensity. Removing the parameters in a double shot noise process gradually, the authors show that it becomes a compound Cox process with shot noise intensity, a single shot noise process and a compound Poisson process. Numerical comparisons are shown between the moments （i.e. means and variances） of a compound Poisson model and their counterparts of a compound Cox model with/without considering a positive interest rate. For that purpose, the authors assume that claim sizes and primary event sizes follow an exponential distribution, respectively.展开更多
The surface of pure copper alloyed with Ti using double glow discharge process was investigated. The morphology, structure and forming mechanism of the Cu-Ti alloying layer were analyzed. The microhardness and wear re...The surface of pure copper alloyed with Ti using double glow discharge process was investigated. The morphology, structure and forming mechanism of the Cu-Ti alloying layer were analyzed. The microhardness and wear resistance of the Cu-Ti alloying layer were measured, and compared with those of pure copper. The results indicate that the surface of copper activated by Ar and Ti ions bombardment is favorable to absorption and diffusion of Ti element. In current experimental temperature, as the Ti content increases, the liquid phase occurs between the deposited layer and diffused layer, which makes the Ti ions and atoms easy to dissolve and the thickness of Cu-Ti alloying layer increase rapidly. After cooling, the structure of the alloying layer is composed of CuTi, Cu4Ti and （Cu（Ti）） solid solution. The solid solution strengthening and precipitation strengthening effects of Ti result in high surface hardness and wear resistance.展开更多
In this paper, we consider a double compound Poisson risk model involving two independent classes ofinsurance risks with a threshold dividend strategy. We derived the integro-differential equations （IDE） with certai...In this paper, we consider a double compound Poisson risk model involving two independent classes ofinsurance risks with a threshold dividend strategy. We derived the integro-differential equations （IDE） with certain boundary conditions for the present value of dividends until ruin. When the claims from both classes are exponentially distributed, we show that the threshold dividend strategy is an optimal dividend strategy.展开更多
Micro-gear is an important actuating component used widely in the micro electro mechanical systems(MEMS) devices.The technologies of micro-forming and precision assembly are urgently developed to manufacture the micro...Micro-gear is an important actuating component used widely in the micro electro mechanical systems(MEMS) devices.The technologies of micro-forming and precision assembly are urgently developed to manufacture the micro-double gear with central shaft.In the paper,a novel hy-brid-forming process with two kinds of piercing method have been proposed to manufacture the micro-double gear using micro forming technology.The tests of hybrid forming process were carried out with two steps and the micro-double gear was successfully manufactured with good surface quality.The results also show that the hybrid micro-forming process with central piercing method can improve the defects of inclining shaft generated by double-ended piercing method.The quality evaluation of micro-double gear was conducted with surface roughness,micro-hardness and impact tests.The results show that the micro-double gear with good mechanical properties can meet the requirements of application for milli-machines.展开更多
The “Double Reduction” policy is not only to reduce the excessive learning burden of students, but also to improve the quality of students’ learning and to promote their overall development. In order to achieve the...The “Double Reduction” policy is not only to reduce the excessive learning burden of students, but also to improve the quality of students’ learning and to promote their overall development. In order to achieve the goal of the “Double Reduction” policy, it is necessary to focus on the implementation of measures to strengthen process evaluation as proposed in the “General Plan for Deepening Education Evaluation Reform in a New Era”. Therefore, the article will analyze the current situation of the research from three aspects: the connotation of “Double Reduction” and process evaluation, process evaluation under “Double Reduction” and process evaluation in English teaching, and look forward to the future development trend, with the aim of implementing the “Double Reduction” policy and giving full play to process evaluation. The aim is to implement the policy of “Double Reduction” and give full play to the role of process evaluation, so as to effectively guide the practice of English teaching.展开更多
The penetration mechanism of aluminum alloy in double-sided gas tungsten arc welding (GTAW) process was probed by means of theoretical analysis, experimentation and numerical simulation. The results show that, firstly...The penetration mechanism of aluminum alloy in double-sided gas tungsten arc welding (GTAW) process was probed by means of theoretical analysis, experimentation and numerical simulation. The results show that, firstly, the welding current goes straight through the weld zone, forms a stronger electromagnetic force field, and causes a stronger fluid flow in the weld pool. Secondly, during double-sided GTAW process, when the weld is partial penetrated, a heat-congregated zone forms between the bottoms of the two weld pools, where the temperature can increase quickly even though only a small amount of heat is input. Thirdly, the buoyancy force causes an inward flow in the bottom weld pool, which can drive the hot liquid on the surface to the bottom of the pool.展开更多
Background: Double-lumen endotracheal (DLT) is commonly used for one-lung ventilation and lung separation during thoracic surgery. There are case reports of medically induced laryngeal granulomas, mainly in patients a...Background: Double-lumen endotracheal (DLT) is commonly used for one-lung ventilation and lung separation during thoracic surgery. There are case reports of medically induced laryngeal granulomas, mainly in patients after single-lumen endotracheal (SLT) tube intubation and tracheotomy, and giant granulomas of the vocal cords due to double-lumen bronchial tube insertion have rarely been reported. Case presentation: A 49-year-old female patient underwent single-port thoracoscopy after DLT intubation as well as a wedge resection of the lower lobe of the left lung, which caused giant vocal process granulomas (VPGs) postoperatively. Based on a retrospective analysis of the general condition, current medical history, past medical history, and visual laryngoscopic observation of the vocal folds tissue, which ruled out preoperative vocal fold granuloma formation, we hypothesized that double-lumen bronchial catheter intubation may have been the primary cause of her vocal fold granuloma formation. Conclusions: Giant granuloma of the vocal folds after DLT insertion is a rare postoperative complication;therefore, if DLT intubation is to be performed, the anesthesiologist should choose an appropriate intubation plan and deal with it promptly to avoid the risk factors to ensure that the patient’s perioperative period is safe and smooth. In addition, if postoperative complications are encountered, they should be followed up and observed on time.展开更多
In this paper, the triple cross and double cross were compared by analysing the characteristics of genetic variation in progeny of triple cross hybrid and double cross hybrid among three parents, based on the successf...In this paper, the triple cross and double cross were compared by analysing the characteristics of genetic variation in progeny of triple cross hybrid and double cross hybrid among three parents, based on the successful breeding practices of Beijing No.10. The results showed that the selection duration of double cross was one year shorter than that of triple cross. The F1 generations of single cross hybrids of double cross showed higher breeding value, and the multiple cross-ing timing of triple cross was more flexible. More wheat varieties have been bred by triple cross, instead of double cross. Moreover, the double cross has a disad-vantage of heavy workload.展开更多
Based on Global Ocean Data Assimilation System （GODAS） and NCEP reanalysis data, atmospheric and oceanic pro- cesses possibly responsible for the onset of the 2011/12 La Nifia event, which followed the 2010/11 La Ni...Based on Global Ocean Data Assimilation System （GODAS） and NCEP reanalysis data, atmospheric and oceanic pro- cesses possibly responsible for the onset of the 2011/12 La Nifia event, which followed the 2010/11 La Nifia even--referred to as a ＂double dip＂ La Nifia--are investigated. The key mechanisms involved in activating the 2011/12 La Nifia are illus- trated by these datasets. Results show that neutral conditions were already evident in the equatorial eastern Pacific during the decaying phase of the 2010/11 La Nifia. However, isothermal analyses show obviously cold water still persisting at the surface and at subsurface depths in off-equatorial regions throughout early 2011, being most pronounced in the tropical South Pacific. The negative SST anomalies in the tropical South Pacific acted to strengthen a southern wind across the equator. The subsurface cold water in the tropical South Pacific then spread northward and broke into the equatorial region at the thermo- cline depth. This incursion process of off-equatorial subsurface cold water successfully interrupted the eastern propagation of warm water along the equator, which had previously accumulated at subsurface depths in the warm pool during the 2010/11 La Nifia event. Furthermore, the incursion process strengthened as a result of the off-equatorial effects, mostly in the tropical South Pacific. The negative SST anomalies then reappeared in the central basin in summer 2011, and acted to trigger local coupled air-sea interactions to produce atmospheric-oceanic anomalies that developed and evolved with the second cooling in the fall of 2011.展开更多
In this work a novel anode configuration consisting of an iron mesh double layer is proposed for the electrochemical treatment of wastewater. The removal of Reactive Black 5 dye（RB5） from synthetic contaminated wate...In this work a novel anode configuration consisting of an iron mesh double layer is proposed for the electrochemical treatment of wastewater. The removal of Reactive Black 5 dye（RB5） from synthetic contaminated water was used as a model system. At a constant anode surface area, identical process operating parameters and batch process mode, the iron mesh double layer electrode showed better performance compared to the conventional single layer iron mesh. The double layer electrode was characterized by RB5 and chemical oxygen demand（COD） removal efficiency of 98.2% and 97.7%, respectively, kinetic rate constant of 0.0385/min, diffusion coefficient of 4.9 × 10^（-5）cm^2/sec and electrical energy consumption of 20.53 kWh/kgdye removed. In the continuous flow system, the optimum conditions suggested by Response Surface Methodology（RSM） are： initial solution p H of 6.29,current density of 1.6 m A/cm^2, electrolyte dose of 0.15 g/L and flow rate of 11.47 m L/min which resulted in an RB5 removal efficiency of 81.62%.展开更多
The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with ...The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.展开更多
A double-sensor probe was used to measure local interfacial parameters of a gas-liquid bubbly flow in a horizontal tube. The parameters included void fraction, interfacial concentration, bubble size distribution, bubb...A double-sensor probe was used to measure local interfacial parameters of a gas-liquid bubbly flow in a horizontal tube. The parameters included void fraction, interfacial concentration, bubble size distribution, bubble frequency and bubble interface velocity. The authors paid special attention to the probe design and construction for minimizing measurement errors. Measures were also taken in the design of sensor ends for preventing corrosions in the flow. This is an effort to improve the current double-sensor probe technique to meet the ever-increasing needs to local parameter measurements in gas-liquid two-phase flows.展开更多
On January 10, 1998, at 11h50min Beijing Time (03h50min UTC), an earthquake of ML=6.2 occurred in the border region between the Zhangbei County and Shangyi County of Hebei Province. This earthquake is the most signifi...On January 10, 1998, at 11h50min Beijing Time (03h50min UTC), an earthquake of ML=6.2 occurred in the border region between the Zhangbei County and Shangyi County of Hebei Province. This earthquake is the most significant event to have occurred in northern China in the recent years. The earthquake-generating structure of this event was not clear due to no active fault capable of generating a moderate earthquake was found in the epicentral area, nor surface ruptures with any predominate orientation were observed, no distinct orientation of its aftershock distribution given by routine earthquake location was shown. To study the seismogenic structure of the Zhangbei- Shangyi earthquake, the main shock and its aftershocks with ML3.0 of the Zhangbei-Shangyi earthquake sequence were relocated by the authors of this paper in 2002 using the master event relative relocation technique. The relocated epicenter of the main shock was located at 41.145癗, 114.462癊, which was located 4 km to the NE of the macro-epicenter of this event. The relocated focal depth of the main shock was 15 km. Hypocenters of the aftershocks distributed in a nearly vertical plane striking 180~200 and its vicinity. The relocated results of the Zhangbei-Shangyi earthquake sequence clearly indicated that the seismogenic structure of this event was a NNE-SSW-striking fault with right-lateral and reverse slip. In this paper, a relocation of the Zhangbei-Shangyi earthquake sequence has been done using the double difference earthquake location algorithm (DD algorithm), and consistent results with that obtained by the master event technique were obtained. The relocated hypocenters of the main shock are located at 41.131癗, 114.456癊, which was located 2.5 km to the NE of the macro-epicenter of the main shock. The relocated focal depth of the main shock was 12.8 km. Hypocenters of the aftershocks also distributed in a nearly vertical N10E-striking plane and its vicinity. The relocated results using DD algorithm clearly indicated that the seismogenic structure of this event was a NNE-striking fault again.展开更多
The mass and thermal coupling makes the control of the reactive double dividing-wall distillation column(R-DDWDC) an especially challenging issue with a highly interactive nature. With reference to the separation of a...The mass and thermal coupling makes the control of the reactive double dividing-wall distillation column(R-DDWDC) an especially challenging issue with a highly interactive nature. With reference to the separation of an ideal endothermic quaternary reversible reaction with the most unfavorable ranking of relative volatilities(A + B ■ C + D with α_(A)>α_(C)>α_(D)>α_(B)), the operation rationality of the R-DDWDC is studied in this contribution. The four-point single temperature control system leads to great steady-state discrepancies in the compositions of products C and D and the reason stems essentially from the failure in keeping strictly the stoichiometric ratio between reactants A and B. A temperature plus temperature cascade control scheme is then employed to reinforce the stoichiometric ratio control and helps to secure a substantial abatement in the steady-state discrepancies. A temperature difference plus temperature cascade control scheme is finally synthesized and leads even to better performance than the most effective double temperature difference control scheme. These outcomes reveal not only the operation feasibility of the R-DDWDC but also the general significance of the proposed temperature difference plus temperature cascade control scheme to the inferential control of any other complicated distillation columns.展开更多
A spheroidal Al_3(Zr,Sc) precipitate with a double-shell structure, comprising a Sc-enriched core enveloped by a Zr-enriched inner shell and a Sc-enriched outer shell(～9 nm in thickness), appears in an Al-0.2 Zr-0.1 ...A spheroidal Al_3(Zr,Sc) precipitate with a double-shell structure, comprising a Sc-enriched core enveloped by a Zr-enriched inner shell and a Sc-enriched outer shell(～9 nm in thickness), appears in an Al-0.2 Zr-0.1 Sc alloy cable after thermomechanical treatment. The average diameter of the spheroidal Al_3(Zr,Sc) precipitate is approximately 80 nm. The double-shelled Al_3(Zr,Sc) precipitate presents three different interfaces and is semi-coherent with the Al matrix. Atom probe tomography(APT) analyses further show that the outer shell of Al_3(Zr,Sc) precipitate is Sc element enrichment. The electrical conductivity of Al-0.2 Zr-0.1 Sc alloy cable increases by 6.5 MS/m within the aging time from 0.2 to 100 h at 350 ℃, with double-shelled Al_3(Zr,Sc)precipitate.展开更多
Two double cold reduction-drawn and redrawn(DRD) tinplate steels of the same chemistries that have been processed by continuous and batch annealing line have been researched. The composition of fibers were studied thr...Two double cold reduction-drawn and redrawn(DRD) tinplate steels of the same chemistries that have been processed by continuous and batch annealing line have been researched. The composition of fibers were studied through X-ray diffraction. The results indicate that a strong intensity of {114}<110> was formed in the continuous annealing steel and a strong intensity of {111}<112> was formed in the batch annealing steel; not only that but the γ fiber slowly rotated to the low angel α fiber with the angel being about 30° nearly {112}<110>texture owing to the higher second reduction.展开更多
文摘The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical T1G backing welding is investigated. The results show that the workpiece experiences double-peak thermal cycle in double-sided asymmetrical TIG backing welding. On the one hand, the fore arc has the pre- heating effect on the rear pass, and the pre-heating temperature depends on the distance between the double arcs, the heat input of fore arc, and the initial temperature of workpiece. On the other hand, the rear arc has the post-heating effect on the fore pass. The mutual effects of two heat sources decrease with the increase of arc distance.
基金Project supported by the National Natural Foundation of China(Grant Nos.51590880,11564030,and 51571126)the National Key Research Program of China(Grant No.2016YFB0700903)+3 种基金Fujian Institute of Innovation,Chinese Academy of Sciences(Grant No.FJCXY18040302)the Key Program of the Chinese Academy of Sciences(Grant No.KJZD-EW-M05-1)the Inner Mongolia Science and Technology Major Project of 2016,Chinathe Natural Science Foundation of Inner Mongolia,China(Grant Nos.2018LH05006 and 2018LH05011)。
文摘Double main phase process is applied to fabricate [(Pr, Nd)1 – xMMx]13.8FebalM1.5B5.9 (x = 0.5 and 0.7;M = Cu, Al, Co, and Nb) sintered magnets with high misch metal (MM) content. In comparison to the magnets by single main phase process, the enhanced magnetic properties have been achieved. For magnets of x = 0.7, Hcj increases to 371.9 kA/m by 60.5%, and (BH)max is significantly enhanced to 253.3 kJ/m3 by 56.9%, compared with those of the single main phase magnets of the same nominal composition. In combination with minor loops and magnetic recoil curves, the property improvement of magnets with double main phase method is well explained. As a result, it is demonstrated that double main phase technology is an effective approach to improve the permanent magnetic properties of MM based sintered magnets.
基金supported by the National Natural Science Foundation of China(No.21477050)the International Scientific and Technological Cooperation in Changzhou(No.CZ20140017)+2 种基金Postgraduate Research Innovation Project of Jiangsu Province(Nos.KYCX20_2561,KYCX20_2598)the Jiangsu Planned Projects for Postdoctoral Research Funds(No.2019K112)the Jiangsu Province subsidizes the recruitment of postdoctoral personnel(No.2019Z143)。
文摘Nonylphenol(NP)residues,as a typical endocrine disrupting chemical(EDC),frequently exist in sewage,surface water,groundwater and even drinking water,which poses a serious threat to human health due to its bioaccumulation.In order to remove NP,a series of MIL-100(Fe)/Zn Fe_(2)O_(4)/flake-like porous carbon nitride(MIL/ZC)was synthesized through in-situ synthesis at room temperature.High performance of ternary MIL/ZC is used to degrade NP under visible light irradiation.The results show that 30MIL/ZC2(20 wt.%Zn Fe_(2)O_(4))ternary composite had the best photocatalytic activity(99.84%)when the dosage was 30 mg.Further mechanism analysis shows that the excellent photocatalytic activity of 30MIL/ZC2could be ascribed to the double charge transfer process between flake-like porous carbon nitride(PCN)and other catalysts in the ternary heterojunction,and the separation of photogenerated electron-hole pairs was more effective.In addition,the 30MIL/ZC2 also showed high stability after five cycles of the photodegradation reaction.Furthermore,the active substance(·O_(2)^(-))was considered to be the main active substance in the NP degradation process.Based on the research results,the possible photocatalytic reaction mechanism of 30MIL/ZC2ternary composite was proposed and discussed in detail.
文摘The authors consider a compound Cox model of insurance risk with the additional economic assumption of a positive interest rate. As the authors note a duality result relating a compound Cox model of insurance risk with a positive interest rate and a double shot noise process, the authors analyze a double shot noise process systematically for its theoretical distributional properties, based on the piecewise deterministic Markov process theory, and the martingale methodology. The authors also obtain the moments of aggregate accumulated/discounted claims where the claim arrival process follows a Cox process with shot noise intensity. Removing the parameters in a double shot noise process gradually, the authors show that it becomes a compound Cox process with shot noise intensity, a single shot noise process and a compound Poisson process. Numerical comparisons are shown between the moments （i.e. means and variances） of a compound Poisson model and their counterparts of a compound Cox model with/without considering a positive interest rate. For that purpose, the authors assume that claim sizes and primary event sizes follow an exponential distribution, respectively.
文摘The surface of pure copper alloyed with Ti using double glow discharge process was investigated. The morphology, structure and forming mechanism of the Cu-Ti alloying layer were analyzed. The microhardness and wear resistance of the Cu-Ti alloying layer were measured, and compared with those of pure copper. The results indicate that the surface of copper activated by Ar and Ti ions bombardment is favorable to absorption and diffusion of Ti element. In current experimental temperature, as the Ti content increases, the liquid phase occurs between the deposited layer and diffused layer, which makes the Ti ions and atoms easy to dissolve and the thickness of Cu-Ti alloying layer increase rapidly. After cooling, the structure of the alloying layer is composed of CuTi, Cu4Ti and （Cu（Ti）） solid solution. The solid solution strengthening and precipitation strengthening effects of Ti result in high surface hardness and wear resistance.
基金Supported by the Natural Science Foundation of Jiangxi Province (2008GQS0035)the Foundation of Zhejiang Provincial Education Department Research Projects (Y200803009)
文摘In this paper, we consider a double compound Poisson risk model involving two independent classes ofinsurance risks with a threshold dividend strategy. We derived the integro-differential equations （IDE） with certain boundary conditions for the present value of dividends until ruin. When the claims from both classes are exponentially distributed, we show that the threshold dividend strategy is an optimal dividend strategy.
基金Funded by the Technology Research and Development Program of China (2006AA04Z331)Young Scholars of Heilongjiang Province (JC-05-11 and JC-06-07)
文摘Micro-gear is an important actuating component used widely in the micro electro mechanical systems(MEMS) devices.The technologies of micro-forming and precision assembly are urgently developed to manufacture the micro-double gear with central shaft.In the paper,a novel hy-brid-forming process with two kinds of piercing method have been proposed to manufacture the micro-double gear using micro forming technology.The tests of hybrid forming process were carried out with two steps and the micro-double gear was successfully manufactured with good surface quality.The results also show that the hybrid micro-forming process with central piercing method can improve the defects of inclining shaft generated by double-ended piercing method.The quality evaluation of micro-double gear was conducted with surface roughness,micro-hardness and impact tests.The results show that the micro-double gear with good mechanical properties can meet the requirements of application for milli-machines.
文摘The “Double Reduction” policy is not only to reduce the excessive learning burden of students, but also to improve the quality of students’ learning and to promote their overall development. In order to achieve the goal of the “Double Reduction” policy, it is necessary to focus on the implementation of measures to strengthen process evaluation as proposed in the “General Plan for Deepening Education Evaluation Reform in a New Era”. Therefore, the article will analyze the current situation of the research from three aspects: the connotation of “Double Reduction” and process evaluation, process evaluation under “Double Reduction” and process evaluation in English teaching, and look forward to the future development trend, with the aim of implementing the “Double Reduction” policy and giving full play to process evaluation. The aim is to implement the policy of “Double Reduction” and give full play to the role of process evaluation, so as to effectively guide the practice of English teaching.
文摘The penetration mechanism of aluminum alloy in double-sided gas tungsten arc welding (GTAW) process was probed by means of theoretical analysis, experimentation and numerical simulation. The results show that, firstly, the welding current goes straight through the weld zone, forms a stronger electromagnetic force field, and causes a stronger fluid flow in the weld pool. Secondly, during double-sided GTAW process, when the weld is partial penetrated, a heat-congregated zone forms between the bottoms of the two weld pools, where the temperature can increase quickly even though only a small amount of heat is input. Thirdly, the buoyancy force causes an inward flow in the bottom weld pool, which can drive the hot liquid on the surface to the bottom of the pool.
文摘Background: Double-lumen endotracheal (DLT) is commonly used for one-lung ventilation and lung separation during thoracic surgery. There are case reports of medically induced laryngeal granulomas, mainly in patients after single-lumen endotracheal (SLT) tube intubation and tracheotomy, and giant granulomas of the vocal cords due to double-lumen bronchial tube insertion have rarely been reported. Case presentation: A 49-year-old female patient underwent single-port thoracoscopy after DLT intubation as well as a wedge resection of the lower lobe of the left lung, which caused giant vocal process granulomas (VPGs) postoperatively. Based on a retrospective analysis of the general condition, current medical history, past medical history, and visual laryngoscopic observation of the vocal folds tissue, which ruled out preoperative vocal fold granuloma formation, we hypothesized that double-lumen bronchial catheter intubation may have been the primary cause of her vocal fold granuloma formation. Conclusions: Giant granuloma of the vocal folds after DLT insertion is a rare postoperative complication;therefore, if DLT intubation is to be performed, the anesthesiologist should choose an appropriate intubation plan and deal with it promptly to avoid the risk factors to ensure that the patient’s perioperative period is safe and smooth. In addition, if postoperative complications are encountered, they should be followed up and observed on time.
文摘In this paper, the triple cross and double cross were compared by analysing the characteristics of genetic variation in progeny of triple cross hybrid and double cross hybrid among three parents, based on the successful breeding practices of Beijing No.10. The results showed that the selection duration of double cross was one year shorter than that of triple cross. The F1 generations of single cross hybrids of double cross showed higher breeding value, and the multiple cross-ing timing of triple cross was more flexible. More wheat varieties have been bred by triple cross, instead of double cross. Moreover, the double cross has a disad-vantage of heavy workload.
基金supported by the National Program for Support of Top-notch Young Professionalsthe National Basic Research Program of China (Grant No.2012CB955202)+2 种基金the Chinese Academy Sciences’ Project "Western Pacific Ocean System: Structure, Dynamics and Consequences" (WPOS Grant No.XDA10010405)the National Natural Science Foundation of China (Grant No.41176014)
文摘Based on Global Ocean Data Assimilation System （GODAS） and NCEP reanalysis data, atmospheric and oceanic pro- cesses possibly responsible for the onset of the 2011/12 La Nifia event, which followed the 2010/11 La Nifia even--referred to as a ＂double dip＂ La Nifia--are investigated. The key mechanisms involved in activating the 2011/12 La Nifia are illus- trated by these datasets. Results show that neutral conditions were already evident in the equatorial eastern Pacific during the decaying phase of the 2010/11 La Nifia. However, isothermal analyses show obviously cold water still persisting at the surface and at subsurface depths in off-equatorial regions throughout early 2011, being most pronounced in the tropical South Pacific. The negative SST anomalies in the tropical South Pacific acted to strengthen a southern wind across the equator. The subsurface cold water in the tropical South Pacific then spread northward and broke into the equatorial region at the thermo- cline depth. This incursion process of off-equatorial subsurface cold water successfully interrupted the eastern propagation of warm water along the equator, which had previously accumulated at subsurface depths in the warm pool during the 2010/11 La Nifia event. Furthermore, the incursion process strengthened as a result of the off-equatorial effects, mostly in the tropical South Pacific. The negative SST anomalies then reappeared in the central basin in summer 2011, and acted to trigger local coupled air-sea interactions to produce atmospheric-oceanic anomalies that developed and evolved with the second cooling in the fall of 2011.
基金the financial support provided by the High Impact Research Grant UM.C/HIR/MOHE/ENG/43the Bright Sparks Program which made this research possible
文摘In this work a novel anode configuration consisting of an iron mesh double layer is proposed for the electrochemical treatment of wastewater. The removal of Reactive Black 5 dye（RB5） from synthetic contaminated water was used as a model system. At a constant anode surface area, identical process operating parameters and batch process mode, the iron mesh double layer electrode showed better performance compared to the conventional single layer iron mesh. The double layer electrode was characterized by RB5 and chemical oxygen demand（COD） removal efficiency of 98.2% and 97.7%, respectively, kinetic rate constant of 0.0385/min, diffusion coefficient of 4.9 × 10^（-5）cm^2/sec and electrical energy consumption of 20.53 kWh/kgdye removed. In the continuous flow system, the optimum conditions suggested by Response Surface Methodology（RSM） are： initial solution p H of 6.29,current density of 1.6 m A/cm^2, electrolyte dose of 0.15 g/L and flow rate of 11.47 m L/min which resulted in an RB5 removal efficiency of 81.62%.
文摘The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.
基金Supported by the National Natural Science Foundation of China(No.59876032)and the Doctorate Foundation of Xi'an Jiaotong University(DFXJU-17).
文摘A double-sensor probe was used to measure local interfacial parameters of a gas-liquid bubbly flow in a horizontal tube. The parameters included void fraction, interfacial concentration, bubble size distribution, bubble frequency and bubble interface velocity. The authors paid special attention to the probe design and construction for minimizing measurement errors. Measures were also taken in the design of sensor ends for preventing corrosions in the flow. This is an effort to improve the current double-sensor probe technique to meet the ever-increasing needs to local parameter measurements in gas-liquid two-phase flows.
文摘On January 10, 1998, at 11h50min Beijing Time (03h50min UTC), an earthquake of ML=6.2 occurred in the border region between the Zhangbei County and Shangyi County of Hebei Province. This earthquake is the most significant event to have occurred in northern China in the recent years. The earthquake-generating structure of this event was not clear due to no active fault capable of generating a moderate earthquake was found in the epicentral area, nor surface ruptures with any predominate orientation were observed, no distinct orientation of its aftershock distribution given by routine earthquake location was shown. To study the seismogenic structure of the Zhangbei- Shangyi earthquake, the main shock and its aftershocks with ML3.0 of the Zhangbei-Shangyi earthquake sequence were relocated by the authors of this paper in 2002 using the master event relative relocation technique. The relocated epicenter of the main shock was located at 41.145癗, 114.462癊, which was located 4 km to the NE of the macro-epicenter of this event. The relocated focal depth of the main shock was 15 km. Hypocenters of the aftershocks distributed in a nearly vertical plane striking 180~200 and its vicinity. The relocated results of the Zhangbei-Shangyi earthquake sequence clearly indicated that the seismogenic structure of this event was a NNE-SSW-striking fault with right-lateral and reverse slip. In this paper, a relocation of the Zhangbei-Shangyi earthquake sequence has been done using the double difference earthquake location algorithm (DD algorithm), and consistent results with that obtained by the master event technique were obtained. The relocated hypocenters of the main shock are located at 41.131癗, 114.456癊, which was located 2.5 km to the NE of the macro-epicenter of the main shock. The relocated focal depth of the main shock was 12.8 km. Hypocenters of the aftershocks also distributed in a nearly vertical N10E-striking plane and its vicinity. The relocated results using DD algorithm clearly indicated that the seismogenic structure of this event was a NNE-striking fault again.
基金the financial support from National Natural Science Foundation of China (21878011)。
文摘The mass and thermal coupling makes the control of the reactive double dividing-wall distillation column(R-DDWDC) an especially challenging issue with a highly interactive nature. With reference to the separation of an ideal endothermic quaternary reversible reaction with the most unfavorable ranking of relative volatilities(A + B ■ C + D with α_(A)>α_(C)>α_(D)>α_(B)), the operation rationality of the R-DDWDC is studied in this contribution. The four-point single temperature control system leads to great steady-state discrepancies in the compositions of products C and D and the reason stems essentially from the failure in keeping strictly the stoichiometric ratio between reactants A and B. A temperature plus temperature cascade control scheme is then employed to reinforce the stoichiometric ratio control and helps to secure a substantial abatement in the steady-state discrepancies. A temperature difference plus temperature cascade control scheme is finally synthesized and leads even to better performance than the most effective double temperature difference control scheme. These outcomes reveal not only the operation feasibility of the R-DDWDC but also the general significance of the proposed temperature difference plus temperature cascade control scheme to the inferential control of any other complicated distillation columns.
基金Project supported by the 2011 Program of the Ministry of Education in China(043010100)
文摘A spheroidal Al_3(Zr,Sc) precipitate with a double-shell structure, comprising a Sc-enriched core enveloped by a Zr-enriched inner shell and a Sc-enriched outer shell(～9 nm in thickness), appears in an Al-0.2 Zr-0.1 Sc alloy cable after thermomechanical treatment. The average diameter of the spheroidal Al_3(Zr,Sc) precipitate is approximately 80 nm. The double-shelled Al_3(Zr,Sc) precipitate presents three different interfaces and is semi-coherent with the Al matrix. Atom probe tomography(APT) analyses further show that the outer shell of Al_3(Zr,Sc) precipitate is Sc element enrichment. The electrical conductivity of Al-0.2 Zr-0.1 Sc alloy cable increases by 6.5 MS/m within the aging time from 0.2 to 100 h at 350 ℃, with double-shelled Al_3(Zr,Sc)precipitate.
基金Sponsored by the National Natural Science Foundation of China(Grant No.U1460101)
文摘Two double cold reduction-drawn and redrawn(DRD) tinplate steels of the same chemistries that have been processed by continuous and batch annealing line have been researched. The composition of fibers were studied through X-ray diffraction. The results indicate that a strong intensity of {114}<110> was formed in the continuous annealing steel and a strong intensity of {111}<112> was formed in the batch annealing steel; not only that but the γ fiber slowly rotated to the low angel α fiber with the angel being about 30° nearly {112}<110>texture owing to the higher second reduction.
