The convective heat transfer and friction behaviors of turbulent tube flow through a straight tape with double-sided delta wings(T-W)have been studied experimentally.In the current work,the T-W formed on the tape was ...The convective heat transfer and friction behaviors of turbulent tube flow through a straight tape with double-sided delta wings(T-W)have been studied experimentally.In the current work,the T-W formed on the tape was used as vortex generators for enhancing the heat transfer coefficient by breakdown of thermal boundary layer and by mixing of fluid flow in tubes.The T-W characteristics are(1)T-W with forward/backward-wing arrangement,(2)T-W with alternate axis(T-WA),(3)three wing-width ratios and(4)wing-pitch ratios.The experimental result reveals that for using the T-W,the increases in the mean Nusselt number(Nu)and friction factor are,respectively,up to 165%and 14.8 times of the plain tube and the maximum thermal performance factor is 1.19.It is also obvious that the T-W with forward-wing gives higher heat transfer rate than one with backward-wing around 7%. The present investigation also shows that the heat transfer rate and friction factor obtained from the T-WA is higher than that from the T-W.In addition,the flow pattern and temperature fields in the T-W tube with both backward and forward wings were also examined numerically.展开更多
The dynamic errors of gyros are the important error sources of a strapdown inertial navigation system. In order to identify the dynamic error model coefficients accurately, the static error model coefficients which la...The dynamic errors of gyros are the important error sources of a strapdown inertial navigation system. In order to identify the dynamic error model coefficients accurately, the static error model coefficients which lay a foundation for compensating while identifying the dynamic error model are identified in the gravity acceleration fields by using angular position function of the three-axis turntable. The angular acceleration and angular velocity are excited on the input, output and spin axis of the gyros when the outer axis and the middle axis of a three-axis turntable are in the uniform angular velocity state simultaneously, while the inner axis of the turntable is in different static angular positions. 8 groups of data are sampled when the inner axis is in 8 different angular positions. These data are the function of the middle axis positions and the inner axis positions. For these data, harmonic analysis method is applied two times versus the middle axis positions and inner axis positions respectively so that the dynamic error model coefficients are finally identified through the least square method. In the meantime the optimal angular velocity of the outer axis and the middle axis are selected by computing the determination value of the information matrix.展开更多
In this paper, the teaching of course Three-dimensional Animation Foundation is designed mainly based on teaching content modularization and scaffolding teaching model. The modularized content design for Three-dimensi...In this paper, the teaching of course Three-dimensional Animation Foundation is designed mainly based on teaching content modularization and scaffolding teaching model. The modularized content design for Three-dimensional Animation Foundation is specifically expounded, and also the ideas for developing the scaffolding teaching model are analyzed. How to integrate the scaffolding teaching model into course teaching is introduced in details. Finally, new methods for guiding students to think independently in course teaching and improve students＇ self-awareness and self-learning ability are proposed.展开更多
The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constrai...The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constraints. The proposed study has concerned TEFC （ totally Enclosed Fan-Cooled ）, 400 V, 50 Hz, SI duty three phase squirrel-cage induction motors only. The motors＇ designs, with AI and Cu cage, have been optimized in order to reach the minimum efficiency level IE3 at lowest active material costs and satisfy the physical and performance constraints of the designs, which are the motor specifications. A suitable optimization procedure has been used which allowed to find the ＂best design＂ by chancing the geometric dimensions of the stator, rotor shape, the stator winding and the stack length. In order to guarantee the goodness and feasibility of the optimized designs, several constrains have been imposed.展开更多
Raman spectra of xLa203-（1-x）TeO2 （x=0, 0.05, 0.10, 0.15, 0.20, and 0.25） lanthanum tellurite glasses were measured and analyzed over the entire glass-forming region in an effort to quantitatively follow the struc...Raman spectra of xLa203-（1-x）TeO2 （x=0, 0.05, 0.10, 0.15, 0.20, and 0.25） lanthanum tellurite glasses were measured and analyzed over the entire glass-forming region in an effort to quantitatively follow the structural changes caused by lanthanum oxide variation. For the first time, systematic intensity measurements have been performed to elucidate the composition induced structural changes in tile high-frequency stretching vibration region and a possible mechanism was proposed. The network structure of the glasses is formed by mixing TeO4 trigonal bipyramid and Te03 trigonal pyramid units. The change of the lanthanum oxide content results in conversion of the TeO4 units to TeO3 units with a varying number of non-bridging oxygen atoms. Analysis of the Raman band contours in terms of vibrations due to different oxygen bridged trigonal bipyramid and trigonal pyramid tellurite structural units, allowed to calculate the relative amounts of the species involved in the structural changes with composition. The fraction of the terminal oxygen atoms has been estimated from the Raman intensities with the aid of a structural model concerning the structure of tellurite network systems. The simulation of the experimental density of lanthanum tellurite glasses with modifier content up to 25% revealed that the short range order building units assumed here are sufficient to account for the overall structure in these glasses.展开更多
Social Work students typically enroll in the required practice methods courses that are specified by the Council on Social Work Education. At least in the majority of BSW Programs, these practice methods courses are d...Social Work students typically enroll in the required practice methods courses that are specified by the Council on Social Work Education. At least in the majority of BSW Programs, these practice methods courses are divided into micro-level and macro-level sequences. Individual and family systems are covered in the former sequence, while communities and organizations are the systems of focus in the latter sequence. The group system is often minimized and/or completely ignored in the process, even though there may be some reference made to groups in both practice methods sequences. Consequently, the mezzo-level system of groups is only given ＂lip-service＂ in the dyadic division of micro and macro-level practice. Furthermore, students often do not have the opportunity to practice in group settings, much less, develop competency in these professional venues. This paper describes a teaching format used in a BSW Program in an effort to ensure student competency as required in a Groups Practice course. The triangular model includes： （1） Classroom teaching of theory; （2） Practice of group dynamics; and （3） Supervision by instructors and MSW students.展开更多
Three-dimensional(3D)nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper.It constructs the complete nonlinear coupl...Three-dimensional(3D)nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper.It constructs the complete nonlinear coupling motion equation without any approximations based on diving relative motion relationship directly,and converts it into linear state space equation with the same relative degree by feedback linearization.With the linear equation,slide mode control with strong robustness is employed to design the guidance law,and 3D diving guidance law which can satisfy terminal impact point and falling angle constraints with high precision is obtained by substituting the previous control law into the origin nonlinear guidance system.Besides,regarding lateral overload as the standard,hybrid control strategy which can take full advantage of the excellent characters of both bank-to-turn(BTT)and skid-to-turn(STT)controls is designed to improve the guidance accuracy further.Finally,the results of CAV-H vehicle guidance test show that the algorithm can realize high accuracy guidance even if serious motion coupling exists,and has strong robustness to the path disturbances and navigation errors as well.展开更多
基金Supported by the Thailand Research Fund(TRF),Office of Higher Education Commission and Mahanakorn University of Technology
文摘The convective heat transfer and friction behaviors of turbulent tube flow through a straight tape with double-sided delta wings(T-W)have been studied experimentally.In the current work,the T-W formed on the tape was used as vortex generators for enhancing the heat transfer coefficient by breakdown of thermal boundary layer and by mixing of fluid flow in tubes.The T-W characteristics are(1)T-W with forward/backward-wing arrangement,(2)T-W with alternate axis(T-WA),(3)three wing-width ratios and(4)wing-pitch ratios.The experimental result reveals that for using the T-W,the increases in the mean Nusselt number(Nu)and friction factor are,respectively,up to 165%and 14.8 times of the plain tube and the maximum thermal performance factor is 1.19.It is also obvious that the T-W with forward-wing gives higher heat transfer rate than one with backward-wing around 7%. The present investigation also shows that the heat transfer rate and friction factor obtained from the T-WA is higher than that from the T-W.In addition,the flow pattern and temperature fields in the T-W tube with both backward and forward wings were also examined numerically.
文摘The dynamic errors of gyros are the important error sources of a strapdown inertial navigation system. In order to identify the dynamic error model coefficients accurately, the static error model coefficients which lay a foundation for compensating while identifying the dynamic error model are identified in the gravity acceleration fields by using angular position function of the three-axis turntable. The angular acceleration and angular velocity are excited on the input, output and spin axis of the gyros when the outer axis and the middle axis of a three-axis turntable are in the uniform angular velocity state simultaneously, while the inner axis of the turntable is in different static angular positions. 8 groups of data are sampled when the inner axis is in 8 different angular positions. These data are the function of the middle axis positions and the inner axis positions. For these data, harmonic analysis method is applied two times versus the middle axis positions and inner axis positions respectively so that the dynamic error model coefficients are finally identified through the least square method. In the meantime the optimal angular velocity of the outer axis and the middle axis are selected by computing the determination value of the information matrix.
文摘In this paper, the teaching of course Three-dimensional Animation Foundation is designed mainly based on teaching content modularization and scaffolding teaching model. The modularized content design for Three-dimensional Animation Foundation is specifically expounded, and also the ideas for developing the scaffolding teaching model are analyzed. How to integrate the scaffolding teaching model into course teaching is introduced in details. Finally, new methods for guiding students to think independently in course teaching and improve students＇ self-awareness and self-learning ability are proposed.
文摘The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constraints. The proposed study has concerned TEFC （ totally Enclosed Fan-Cooled ）, 400 V, 50 Hz, SI duty three phase squirrel-cage induction motors only. The motors＇ designs, with AI and Cu cage, have been optimized in order to reach the minimum efficiency level IE3 at lowest active material costs and satisfy the physical and performance constraints of the designs, which are the motor specifications. A suitable optimization procedure has been used which allowed to find the ＂best design＂ by chancing the geometric dimensions of the stator, rotor shape, the stator winding and the stack length. In order to guarantee the goodness and feasibility of the optimized designs, several constrains have been imposed.
文摘Raman spectra of xLa203-（1-x）TeO2 （x=0, 0.05, 0.10, 0.15, 0.20, and 0.25） lanthanum tellurite glasses were measured and analyzed over the entire glass-forming region in an effort to quantitatively follow the structural changes caused by lanthanum oxide variation. For the first time, systematic intensity measurements have been performed to elucidate the composition induced structural changes in tile high-frequency stretching vibration region and a possible mechanism was proposed. The network structure of the glasses is formed by mixing TeO4 trigonal bipyramid and Te03 trigonal pyramid units. The change of the lanthanum oxide content results in conversion of the TeO4 units to TeO3 units with a varying number of non-bridging oxygen atoms. Analysis of the Raman band contours in terms of vibrations due to different oxygen bridged trigonal bipyramid and trigonal pyramid tellurite structural units, allowed to calculate the relative amounts of the species involved in the structural changes with composition. The fraction of the terminal oxygen atoms has been estimated from the Raman intensities with the aid of a structural model concerning the structure of tellurite network systems. The simulation of the experimental density of lanthanum tellurite glasses with modifier content up to 25% revealed that the short range order building units assumed here are sufficient to account for the overall structure in these glasses.
文摘Social Work students typically enroll in the required practice methods courses that are specified by the Council on Social Work Education. At least in the majority of BSW Programs, these practice methods courses are divided into micro-level and macro-level sequences. Individual and family systems are covered in the former sequence, while communities and organizations are the systems of focus in the latter sequence. The group system is often minimized and/or completely ignored in the process, even though there may be some reference made to groups in both practice methods sequences. Consequently, the mezzo-level system of groups is only given ＂lip-service＂ in the dyadic division of micro and macro-level practice. Furthermore, students often do not have the opportunity to practice in group settings, much less, develop competency in these professional venues. This paper describes a teaching format used in a BSW Program in an effort to ensure student competency as required in a Groups Practice course. The triangular model includes： （1） Classroom teaching of theory; （2） Practice of group dynamics; and （3） Supervision by instructors and MSW students.
基金supported by the National Natural Science Foundation of China(Grant No.61104200)the National University of Defense Technology Innovation Foundation for Postgraduates(Grant No.B140103)
文摘Three-dimensional(3D)nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper.It constructs the complete nonlinear coupling motion equation without any approximations based on diving relative motion relationship directly,and converts it into linear state space equation with the same relative degree by feedback linearization.With the linear equation,slide mode control with strong robustness is employed to design the guidance law,and 3D diving guidance law which can satisfy terminal impact point and falling angle constraints with high precision is obtained by substituting the previous control law into the origin nonlinear guidance system.Besides,regarding lateral overload as the standard,hybrid control strategy which can take full advantage of the excellent characters of both bank-to-turn(BTT)and skid-to-turn(STT)controls is designed to improve the guidance accuracy further.Finally,the results of CAV-H vehicle guidance test show that the algorithm can realize high accuracy guidance even if serious motion coupling exists,and has strong robustness to the path disturbances and navigation errors as well.
