The selection of an appropriate basic detonation wave flow field is crucial for improving the performance and geometric design of standing detonation vehicles.This paper employs a detailed chemical reaction model and ...The selection of an appropriate basic detonation wave flow field is crucial for improving the performance and geometric design of standing detonation vehicles.This paper employs a detailed chemical reaction model and solves the unsteady axisymmetric Euler equation to study the characteristics of the Axisymmetric Inward Turning Curved Detonation Wave(AIT-CDW)flow field and the parameters affecting the stability of the wave system structure of AIT-CDW flow field.The numerical results demonstrate a radial compression effect in the AIT-CDW flow field.This effect causes the detonation wave to have a shorter initiation length than oblique detonation wave flow field and the detonation wave angle to gradually increase with the flow direction postdetonation.The AIT-CDW flow field is confined space,making it prone to normal detonation waves when the detonation wave reflects from the wall.This phenomenon is detrimental to the stability of the wave system structure in the flow field.It has been observed that increasing the center body radius and decreasing the fuel equivalent ratio can effectively reduce the height of the normal detonation wave or even eliminate it.Additionally,a well-designed generatrix shape of the center body can enhance airflow,reduce choked flow,and promote the stability of the wave structure in the flow field.展开更多
Located in the southeast corner of Norbulingka Palace Park in Lhasa,the Xizang Museum stands out as a facility integrating contemporary technology,design and practices with the regional characteristics of Xizang Auton...Located in the southeast corner of Norbulingka Palace Park in Lhasa,the Xizang Museum stands out as a facility integrating contemporary technology,design and practices with the regional characteristics of Xizang Autonomous Region,southwest China.The museum houses over 520,000 cultural relics,including silk pieces,religious instruments,ancient books and documents,porcelain and jade articles,enamel vessels,and silverware,as well as Thangka paintings.展开更多
The turning performance of a ship is an important aspect of its maneuverability,and accurately predicting the hydrodynamic forces during ship turning motion is of great significance for the safe maneuvering design of ...The turning performance of a ship is an important aspect of its maneuverability,and accurately predicting the hydrodynamic forces during ship turning motion is of great significance for the safe maneuvering design of ships.This paper investigated the hydrodynamic performance of a KRISO container ship in steady turning using experimental and numerical approaches.The rotating arm tests were carried out in rotating arm basin of Zhejiang University,while the numerical simulations were conducted in commercial computational fluid dynamics software.Hydrodynamic forces and moments,hull surface wave height,wave patterns,and vorticity are studied under different velocities,radii,and drift angles.The results show that the increase in velocity has a significant impact on the forces and moments of the hull.The changes in longitudinal and transverse forces reflect the complex fluid dynamic interactions between the hull and water.Under conditions of small radius and large drift angle,the hull experiences greater forces and moments,indicating that stability and maneuverability will be more challenged during sudden turns.This study can provide experimental data and numerical simulation references for the research of ship turning maneuvers.展开更多
Laser assisted turning （LAT） is one of the advanced machining technologies, which uses laser power to heat the surface of a workpiece before the material is removed. It has several advantages of low manufacturing co...Laser assisted turning （LAT） is one of the advanced machining technologies, which uses laser power to heat the surface of a workpiece before the material is removed. It has several advantages of low manufacturing costs, high productivity and high qualities to machine difficult-to-cut materials such as silicon nitride, muUite, zirconia and Ni. A large part of studies on LAT have been focused on a round bar. With increasing demands for high quality products and high performance engineering system, the researches on LAT for clover and square section members are necessary. But, these workpieces are impossible to be machined on conventional CNC lathe and to generate NC code with current CAM softwares. As a basic research for combining LAT with a tilting index table type 5-axis machining center, i.e. laser assisted turn-mill, a new method is suggested to generate NC code that can process various types of clover and square section members through development of C＋＋ program.展开更多
An ultra-high voltage 4H-silicon carbide(Si C) gate turn-off(GTO) thyristor for low switching time is proposed and analyzed by numerical simulation. It features a double epitaxial p-base in which an extra electrical f...An ultra-high voltage 4H-silicon carbide(Si C) gate turn-off(GTO) thyristor for low switching time is proposed and analyzed by numerical simulation. It features a double epitaxial p-base in which an extra electrical field is induced to enhance the transportation of the electrons in the thin p-base and reduce recombination. As a result, the turn-on characteristics are improved. What is more, to obtain a low turn-off loss, an alternating p^+/n^+region formed in the backside acts as the anode in the GTO thyristor. Consequently, another path formed by the reverse-biased n^+–p junction accelerates the fast removal of excess electrons during turn-off. This work demonstrates that the turn-on time and turn-off time of the new structure are reduced to 37 ns and 783.1 ns, respectively, under a bus voltage of 8000 V and load current of 100 A/cm^2.展开更多
Translation has been the subject of a variety of research and conflicts among theorists. This fact that gives Thomas Samuel Kuhn＇s paradigm theory is pertinent to the present study. Kuhn is an American philosopher of...Translation has been the subject of a variety of research and conflicts among theorists. This fact that gives Thomas Samuel Kuhn＇s paradigm theory is pertinent to the present study. Kuhn is an American philosopher of Science. In his book The Structure of Scientific Revolutions, he proposes his paradigm theory which plays a great role in the development of sociology and philosophy of Science. According to Kuhn （1970）, paradigm originates from one or some famous people＇s achievements, and for these achievements to be considered as paradigms, two major characteristics must be met as will be clarified in this paper. This study is an attempt to outline the scope of the disciplines of Translation Studies （TS）, to give some indication of the kind of work that has been done so far. It is an attempt to demonstrate that TS is a discipline in its own right. It is a vastly complex field with many far-reaching ramifications. This study discusses the relationships between the changing definitions of translation and the turns of translation studies.展开更多
Using early indica rice Zhongzao 39 and japonica rice Xiushui 134 as the experimental materials, the effects of 4 temperature levels after transplantation on turning green, leaf growth, tillering, dry matter accumulat...Using early indica rice Zhongzao 39 and japonica rice Xiushui 134 as the experimental materials, the effects of 4 temperature levels after transplantation on turning green, leaf growth, tillering, dry matter accumulation and nutrition absorption were studied using a greenhouse and an artificial climate chest. We found that （1） tillering did not occur and growth of one new leaf took over 15 days at 16℃. New leaf growth took over 10 days and tillering occurred after 15 days of transplanta- tion at 19 ℃. Tillering appeared 10 days after planting and new leaf growth took 5 days between 22 and 25 ℃. This showed that low temperature impeded the turn- ing green of rice seedlings and the temperature must reach above 19 ℃ to ensure timely appearance of new leaf, tillering and turning green in rice seedlings. （2） When the temperature was 10 increased, both 100-seedling dry weight and nitrogen absorption increased. At temperatures lower 11 than 19 ℃, both dry weight incre- ment and nitrogen absorption were low. Nitrogen absorption of all organs increased obviously between 19 and 22 ℃. Thus, 19 ℃ was found to be an minimum tem- perature for plant organs to absorb nutrients. （3）Tiller of seedling cultivated on dry- land soil and substrate grew quickly and tillering occurred about 7 days after trans- planting. After that, the growth rate was about 0.18 tiller per day. For seedlings cultivated in slurry, tillering occurred 10 days after transplanting and the tillers grew at a rate of 0.16 tiller per day. However, substrate choice during the seedling rais- ing stage had no significant influence on leaf age. （4） Japonica rice exhibited stronger resistance to low temperature than indica rice. Tillering began at about the same time after transplanting in both rice varieties, but japonica rice exhibited higher tillering speed than early indica rice. The speed of leaf growth was higher in japoni- ca rice before transplantation but higher in indica rice after transplantation.展开更多
Field observations illustrated that, right-turn vehicles stopped at various positions when proceeding within the right-turn lanes, while some of them trespassed on the crosswalks with multiple stops. In this case, ped...Field observations illustrated that, right-turn vehicles stopped at various positions when proceeding within the right-turn lanes, while some of them trespassed on the crosswalks with multiple stops. In this case, pedestrians and bikes (ped/bike) are encountered unsmooth and hazardous crossings when right-turn vehicles encroaching their lanes. Meanwhile, this also causes conflicts between right-turn and through vehicles at the crossing street. To better protect ped/bike at crossings with right-turn vehicles, this paper proposes a concept of “right-turn vehicle box” (RTVB) as a supplemental treatment within right-turn lanes. Sight distance, geometric conditions, and behaviors of vehicles and ped/bike are key factors to consider so as to set up the criteria and to design the suitable treatment. A case study was conducted at an intersection pair in Houston, USA to shape the idea of RTVB, together with driving simulator tests under relevant scenarios. The preliminary crosscheck examination shows that the right-turn vehicle box could possibly provide ped/ bike with smoother and safer crossings. In the interim, the safety and efficiency of right-turn operations were also improved. To further validate the effects, implementation studies should be conducted before the RTVB can make its debut in practice. Future works will focus on the complete warrants and design details of this treatment. Moreover, the concept of “vehicle box” could also be transplanted to other places where turning movement(s) needs assistance or improvements.展开更多
The power relations in the TV program called If You Are the One will be explored from the perspective of the turns of different speakers on the different positions,such as the host,male vips,female vips and two co...The power relations in the TV program called If You Are the One will be explored from the perspective of the turns of different speakers on the different positions,such as the host,male vips,female vips and two commentators.Using both quantitative and qualitative methods,the reversion of the program,updated on June 9,2018 on the internet,is sampled.Then,the analyses on respective turns of different speakers are from two main perspectives of the turn-constructional component and turn-allocation component.The results show that the host has more power than others and the role two commentators play in the program is very important.Analyzing the power relations in these conversations of the program helps readers more positively and effectively understand the operation mechanism of this program after reversion.展开更多
In this paper, we study a class singular perturbed elliptic equation boundary value problem with a super surface of turning point in n-dimensional space by using the method of multiple scales and the comparison theore...In this paper, we study a class singular perturbed elliptic equation boundary value problem with a super surface of turning point in n-dimensional space by using the method of multiple scales and the comparison theorem. The uniformly valid asymptotic approxmations of solutions for the boundary value problem is constructed.展开更多
The current research of suspension performance evaluation is mixed in the evaluation of vehicle handling and ride comfort. However, it is lack of a direct and independent evaluation method for suspension performance. ...The current research of suspension performance evaluation is mixed in the evaluation of vehicle handling and ride comfort. However, it is lack of a direct and independent evaluation method for suspension performance. In this paper, a novel wheel turn center method is proposed to evaluate the suspension performance. This method is based on the concept and application of wheel turn center （WTC） and sprung mass turn center （SPTC）. The vehicle body and each wheel are regarded to be independent rigid bodies and have their own turn centers which reflect respective steering motions and responses. Since the suspension is the link between vehicle body and wheels, the consistence between the sprung mass turn center and the wheel turn center reflects the effect and performance of the suspension system. Firstly, the concept and appropriate calculation method of WTC and SPTC are developed. Then the degree of inconsistence between WTC and SPTC and the time that they achieve consistence, when the vehicle experiences from transient steering to steady steering state, are proposed to evaluate suspension performance. The suspension evaluation tests are conducted under different vehicle velocities and lateral accelerations by using CarSim software. The simulation results show that the inconsistence of steering motion between vehicle body and wheels are mainly at high speeds and low lateral accelerations. Finally, based on the proposed evaluation indexes, the influences of different suspension characteristic parameters on suspension performance and their matches to improve steering coordination are discussed. The proposed wheel turn center method provides a guidance and potential application for suspension evaluation and optimization.展开更多
Turning gait is a basic motion for humanoid robots. This paper presents a method for humanoid tuming, i.e. clock-turning. The objective of clock-turning is to change robot direction at a stationary spot. The clock-tur...Turning gait is a basic motion for humanoid robots. This paper presents a method for humanoid tuming, i.e. clock-turning. The objective of clock-turning is to change robot direction at a stationary spot. The clock-turning planning consists of four steps： ankle trajectory generation, hip trajectory generation, knee trajectory generation, and inverse kinematics calculation. Our proposed method is based on a typical humanoid structure with 12 DOFs （degrees of freedom）. The final output of clock-turning planning is 12 reference trajectories, which are used to control a humanoid robot with 12 DOFs. ZMP （zero moment point） is used as stability criterion for the planning. Simulation experiments are conducted to verify the effectiveness of our proposed clock-turuing method.展开更多
Two methods based on a slight modification of the regular traffic assignmentalgorithms are proposed to directly compute turn flows instead of estimating them from link flows orobtaining them by expanding the networks....Two methods based on a slight modification of the regular traffic assignmentalgorithms are proposed to directly compute turn flows instead of estimating them from link flows orobtaining them by expanding the networks. The first one is designed on the path-turn incidencerelationship, and it is similar to the computational procedure of link flows. It applies to thetraffic assignment algorithms that can provide detailed path structures. The second utilizes thelink-turn incidence relationship and the conservation of flow on links, a law deriving from thisrelationship. It is actually an improved version of Dial's logit assignment algorithm. The proposedapproaches can avoid the shortcomings both of the estimation methods, e. g. Furness's model andFrator's model, and of the network-expanding method in precision, stability and computation scale.Finally, they are validated by numerical examples.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U20A2069,62376234 and 123B2037)the Advanced Aero-Power Innovation Workstation,China(No.HKCX2024-01-017)。
文摘The selection of an appropriate basic detonation wave flow field is crucial for improving the performance and geometric design of standing detonation vehicles.This paper employs a detailed chemical reaction model and solves the unsteady axisymmetric Euler equation to study the characteristics of the Axisymmetric Inward Turning Curved Detonation Wave(AIT-CDW)flow field and the parameters affecting the stability of the wave system structure of AIT-CDW flow field.The numerical results demonstrate a radial compression effect in the AIT-CDW flow field.This effect causes the detonation wave to have a shorter initiation length than oblique detonation wave flow field and the detonation wave angle to gradually increase with the flow direction postdetonation.The AIT-CDW flow field is confined space,making it prone to normal detonation waves when the detonation wave reflects from the wall.This phenomenon is detrimental to the stability of the wave system structure in the flow field.It has been observed that increasing the center body radius and decreasing the fuel equivalent ratio can effectively reduce the height of the normal detonation wave or even eliminate it.Additionally,a well-designed generatrix shape of the center body can enhance airflow,reduce choked flow,and promote the stability of the wave structure in the flow field.
文摘Located in the southeast corner of Norbulingka Palace Park in Lhasa,the Xizang Museum stands out as a facility integrating contemporary technology,design and practices with the regional characteristics of Xizang Autonomous Region,southwest China.The museum houses over 520,000 cultural relics,including silk pieces,religious instruments,ancient books and documents,porcelain and jade articles,enamel vessels,and silverware,as well as Thangka paintings.
基金supported by the China Scholarship Council(Grant No.202306320084).
文摘The turning performance of a ship is an important aspect of its maneuverability,and accurately predicting the hydrodynamic forces during ship turning motion is of great significance for the safe maneuvering design of ships.This paper investigated the hydrodynamic performance of a KRISO container ship in steady turning using experimental and numerical approaches.The rotating arm tests were carried out in rotating arm basin of Zhejiang University,while the numerical simulations were conducted in commercial computational fluid dynamics software.Hydrodynamic forces and moments,hull surface wave height,wave patterns,and vorticity are studied under different velocities,radii,and drift angles.The results show that the increase in velocity has a significant impact on the forces and moments of the hull.The changes in longitudinal and transverse forces reflect the complex fluid dynamic interactions between the hull and water.Under conditions of small radius and large drift angle,the hull experiences greater forces and moments,indicating that stability and maneuverability will be more challenged during sudden turns.This study can provide experimental data and numerical simulation references for the research of ship turning maneuvers.
基金Project(2011-0017407)supported by the National Research Foundation of Korea(NRF)funded by Korea government(MEST)
文摘Laser assisted turning （LAT） is one of the advanced machining technologies, which uses laser power to heat the surface of a workpiece before the material is removed. It has several advantages of low manufacturing costs, high productivity and high qualities to machine difficult-to-cut materials such as silicon nitride, muUite, zirconia and Ni. A large part of studies on LAT have been focused on a round bar. With increasing demands for high quality products and high performance engineering system, the researches on LAT for clover and square section members are necessary. But, these workpieces are impossible to be machined on conventional CNC lathe and to generate NC code with current CAM softwares. As a basic research for combining LAT with a tilting index table type 5-axis machining center, i.e. laser assisted turn-mill, a new method is suggested to generate NC code that can process various types of clover and square section members through development of C＋＋ program.
基金Project supported by the National Natural Science Foundation of China(Grant No.51677149)
文摘An ultra-high voltage 4H-silicon carbide(Si C) gate turn-off(GTO) thyristor for low switching time is proposed and analyzed by numerical simulation. It features a double epitaxial p-base in which an extra electrical field is induced to enhance the transportation of the electrons in the thin p-base and reduce recombination. As a result, the turn-on characteristics are improved. What is more, to obtain a low turn-off loss, an alternating p^+/n^+region formed in the backside acts as the anode in the GTO thyristor. Consequently, another path formed by the reverse-biased n^+–p junction accelerates the fast removal of excess electrons during turn-off. This work demonstrates that the turn-on time and turn-off time of the new structure are reduced to 37 ns and 783.1 ns, respectively, under a bus voltage of 8000 V and load current of 100 A/cm^2.
文摘Translation has been the subject of a variety of research and conflicts among theorists. This fact that gives Thomas Samuel Kuhn＇s paradigm theory is pertinent to the present study. Kuhn is an American philosopher of Science. In his book The Structure of Scientific Revolutions, he proposes his paradigm theory which plays a great role in the development of sociology and philosophy of Science. According to Kuhn （1970）, paradigm originates from one or some famous people＇s achievements, and for these achievements to be considered as paradigms, two major characteristics must be met as will be clarified in this paper. This study is an attempt to outline the scope of the disciplines of Translation Studies （TS）, to give some indication of the kind of work that has been done so far. It is an attempt to demonstrate that TS is a discipline in its own right. It is a vastly complex field with many far-reaching ramifications. This study discusses the relationships between the changing definitions of translation and the turns of translation studies.
基金Supported by Special Scientific Research Funds for Commonweal Section(Agriculture)(201203029,201003016)China Rice Industry System Project(2011-2015)Special Funding for Basic Scientific Research and Zhejiang Provincial Natural Science Foundation(LY13C130004)~~
文摘Using early indica rice Zhongzao 39 and japonica rice Xiushui 134 as the experimental materials, the effects of 4 temperature levels after transplantation on turning green, leaf growth, tillering, dry matter accumulation and nutrition absorption were studied using a greenhouse and an artificial climate chest. We found that （1） tillering did not occur and growth of one new leaf took over 15 days at 16℃. New leaf growth took over 10 days and tillering occurred after 15 days of transplanta- tion at 19 ℃. Tillering appeared 10 days after planting and new leaf growth took 5 days between 22 and 25 ℃. This showed that low temperature impeded the turn- ing green of rice seedlings and the temperature must reach above 19 ℃ to ensure timely appearance of new leaf, tillering and turning green in rice seedlings. （2） When the temperature was 10 increased, both 100-seedling dry weight and nitrogen absorption increased. At temperatures lower 11 than 19 ℃, both dry weight incre- ment and nitrogen absorption were low. Nitrogen absorption of all organs increased obviously between 19 and 22 ℃. Thus, 19 ℃ was found to be an minimum tem- perature for plant organs to absorb nutrients. （3）Tiller of seedling cultivated on dry- land soil and substrate grew quickly and tillering occurred about 7 days after trans- planting. After that, the growth rate was about 0.18 tiller per day. For seedlings cultivated in slurry, tillering occurred 10 days after transplanting and the tillers grew at a rate of 0.16 tiller per day. However, substrate choice during the seedling rais- ing stage had no significant influence on leaf age. （4） Japonica rice exhibited stronger resistance to low temperature than indica rice. Tillering began at about the same time after transplanting in both rice varieties, but japonica rice exhibited higher tillering speed than early indica rice. The speed of leaf growth was higher in japoni- ca rice before transplantation but higher in indica rice after transplantation.
文摘Field observations illustrated that, right-turn vehicles stopped at various positions when proceeding within the right-turn lanes, while some of them trespassed on the crosswalks with multiple stops. In this case, pedestrians and bikes (ped/bike) are encountered unsmooth and hazardous crossings when right-turn vehicles encroaching their lanes. Meanwhile, this also causes conflicts between right-turn and through vehicles at the crossing street. To better protect ped/bike at crossings with right-turn vehicles, this paper proposes a concept of “right-turn vehicle box” (RTVB) as a supplemental treatment within right-turn lanes. Sight distance, geometric conditions, and behaviors of vehicles and ped/bike are key factors to consider so as to set up the criteria and to design the suitable treatment. A case study was conducted at an intersection pair in Houston, USA to shape the idea of RTVB, together with driving simulator tests under relevant scenarios. The preliminary crosscheck examination shows that the right-turn vehicle box could possibly provide ped/ bike with smoother and safer crossings. In the interim, the safety and efficiency of right-turn operations were also improved. To further validate the effects, implementation studies should be conducted before the RTVB can make its debut in practice. Future works will focus on the complete warrants and design details of this treatment. Moreover, the concept of “vehicle box” could also be transplanted to other places where turning movement(s) needs assistance or improvements.
文摘The power relations in the TV program called If You Are the One will be explored from the perspective of the turns of different speakers on the different positions,such as the host,male vips,female vips and two commentators.Using both quantitative and qualitative methods,the reversion of the program,updated on June 9,2018 on the internet,is sampled.Then,the analyses on respective turns of different speakers are from two main perspectives of the turn-constructional component and turn-allocation component.The results show that the host has more power than others and the role two commentators play in the program is very important.Analyzing the power relations in these conversations of the program helps readers more positively and effectively understand the operation mechanism of this program after reversion.
文摘In this paper, we study a class singular perturbed elliptic equation boundary value problem with a super surface of turning point in n-dimensional space by using the method of multiple scales and the comparison theorem. The uniformly valid asymptotic approxmations of solutions for the boundary value problem is constructed.
基金Supported by Changjiang Scholar and Innovative Research Team Plan of China(Grant No.IRT0626)
文摘The current research of suspension performance evaluation is mixed in the evaluation of vehicle handling and ride comfort. However, it is lack of a direct and independent evaluation method for suspension performance. In this paper, a novel wheel turn center method is proposed to evaluate the suspension performance. This method is based on the concept and application of wheel turn center （WTC） and sprung mass turn center （SPTC）. The vehicle body and each wheel are regarded to be independent rigid bodies and have their own turn centers which reflect respective steering motions and responses. Since the suspension is the link between vehicle body and wheels, the consistence between the sprung mass turn center and the wheel turn center reflects the effect and performance of the suspension system. Firstly, the concept and appropriate calculation method of WTC and SPTC are developed. Then the degree of inconsistence between WTC and SPTC and the time that they achieve consistence, when the vehicle experiences from transient steering to steady steering state, are proposed to evaluate suspension performance. The suspension evaluation tests are conducted under different vehicle velocities and lateral accelerations by using CarSim software. The simulation results show that the inconsistence of steering motion between vehicle body and wheels are mainly at high speeds and low lateral accelerations. Finally, based on the proposed evaluation indexes, the influences of different suspension characteristic parameters on suspension performance and their matches to improve steering coordination are discussed. The proposed wheel turn center method provides a guidance and potential application for suspension evaluation and optimization.
基金This work was supported by the National Natural Science Foundation of China (No. 60174018).
文摘Turning gait is a basic motion for humanoid robots. This paper presents a method for humanoid tuming, i.e. clock-turning. The objective of clock-turning is to change robot direction at a stationary spot. The clock-turning planning consists of four steps： ankle trajectory generation, hip trajectory generation, knee trajectory generation, and inverse kinematics calculation. Our proposed method is based on a typical humanoid structure with 12 DOFs （degrees of freedom）. The final output of clock-turning planning is 12 reference trajectories, which are used to control a humanoid robot with 12 DOFs. ZMP （zero moment point） is used as stability criterion for the planning. Simulation experiments are conducted to verify the effectiveness of our proposed clock-turuing method.
文摘Two methods based on a slight modification of the regular traffic assignmentalgorithms are proposed to directly compute turn flows instead of estimating them from link flows orobtaining them by expanding the networks. The first one is designed on the path-turn incidencerelationship, and it is similar to the computational procedure of link flows. It applies to thetraffic assignment algorithms that can provide detailed path structures. The second utilizes thelink-turn incidence relationship and the conservation of flow on links, a law deriving from thisrelationship. It is actually an improved version of Dial's logit assignment algorithm. The proposedapproaches can avoid the shortcomings both of the estimation methods, e. g. Furness's model andFrator's model, and of the network-expanding method in precision, stability and computation scale.Finally, they are validated by numerical examples.
