Enterprises are facing problems such as the dynamic matching of talents and strategies,and the construction of organizational resilience.Based on this,this paper deeply explores the significance of the research on the...Enterprises are facing problems such as the dynamic matching of talents and strategies,and the construction of organizational resilience.Based on this,this paper deeply explores the significance of the research on the“Double Helix”model of strategic human resource management in the VUCA era and the practical construction of the“Double Helix”model:the implementation path of key dimensions,aiming to achieve the coordinated progress of the two through strategies such as improving talent density,forging organizational resilience,and promoting the coordinated integration mechanism of the Double Helix,so as to provide scientific human resource management strategies for enterprises,help enterprises enhance their competitiveness in a complex and changeable environment,and achieve sustainable development.展开更多
The experimental realization of observable phonon angular momentum(PAM)in feasible systems using relatively simple methods remains a critical challenge.Motivated by the chiral-induced spin selectivity effect,this stud...The experimental realization of observable phonon angular momentum(PAM)in feasible systems using relatively simple methods remains a critical challenge.Motivated by the chiral-induced spin selectivity effect,this study explores the generation of PAM during the transport of electrically driven polarons along a singlestranded helix structure.We demonstrate that the motion of a polaron under an applied electric field inherently induces a finite PAM,exhibiting drift-locked behavior between the PAM and the polaron.By analyzing the time evolution of PAM distribution at each site,we identify the observed PAM as a natural consequence of coherent superposition between lattice waves,in which the chiral structure selectively determines the direction of induced PAM.Furthermore,we examine the roles of two types of electron-phonon interactions and structural periodicity in modulating PAM.These findings highlight the potential of chiral molecules as platforms for PAM generation and offer new insights into developing phonon-spin-based devices for information processing and transmission.展开更多
Recent theoretical work has predicted the existence of a“dipole spiral”structure in strained freestanding membranes of PbTiO_(3),suggesting a potential route to enhanced electromechanical responses[Phys.Rev.Lett.133...Recent theoretical work has predicted the existence of a“dipole spiral”structure in strained freestanding membranes of PbTiO_(3),suggesting a potential route to enhanced electromechanical responses[Phys.Rev.Lett.133046802(2024)].However,its microscopic nature,energetic landscape,and electronic properties remain largely unexplored from a first-principles perspective.Here,using density functional theory on PbTiO3 under biaxial tensile strain,we identify a novel form of polar order:a chiral,non-collinear ferroelectric double helix.We find that two distinct,intertwined polarization helices are formed by the local Pb-O and Ti-O dipoles,reminiscent of DNA.This topology is stabilized by a collective helical twisting of the encompassing oxygen cages(the polyhedra for both Pb and Ti cations),which gives rise to an electric Dzyaloshinskii–Moriya-like interaction.The resulting structure,which can be conceptualized as a“self-moiré”crystal,exhibits two coupled functionalities.First,it possesses a rotational pseudo-zero-energy mode that underpins a giant piezoelectric response(e_(33)≈16C/m^(2)).Second,the long-period potential reconstructs the electronic band structure,leading to a multi-valley electronic topology at the valence band edge.Our work establishes a physical route to designing complex chiral order that supports both giant electromechanical coupling and multi-valley electronics.展开更多
The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid i...The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid in the shell-side channel is focused on. The results on meridian planes indicate that in the shell-side channel, the center part of fluid has an outward tendency because of the centrifugal force, and the peripheral region fluid has an inward tendency under the centripetal force. So in a spiral cycle, the fluid is divided into the upper and lower beams of streamlines, at the same time the Dean vortices are formed near the left baffle, and then the fluid turns to centripetal flow near the right baffle. Finally the two beams of streamlines merge in the main flow. The results of a number of parallel slices between two parallel baffles with the same sector in a swirl cycle also show the existence of the secondary flow and some backward flows at the V-gaps of the adjacent baffles. The secondary flows have a positive effect on mixing fluid by promoting the momentum and mass exchange between fluid particles near the tube wall and in the main stream, and thus they will enhance the heat transfer of the helix heat exchanger.展开更多
An integrated dynamic model considering the influence of the helix angle is developed through dividing the cutting process into three cutting processes： uninterrupted, entry, and exit cutting processes. The semi-disc...An integrated dynamic model considering the influence of the helix angle is developed through dividing the cutting process into three cutting processes： uninterrupted, entry, and exit cutting processes. The semi-discretized technique is used to approximate the finite dimensional Floquet transition matrix of the dynamic control equation to determine the stability of milling process. The stability charts for helix mills are obtained. Results show that the helix angle plays an important role in the stability of milling process. The stability regions with helix angle become larger than those without helix angle. Some ＂islands＂ are presented in the stability charts, and ＂island＂ locations are determined by the relation between the axial depth of cut and the helix pitch. The ＂islands＂ are connected by the ＂bridge＂ by the effects of entry and exit cutting processes. The theoretical results are validated by milling experiments.展开更多
基金Horizontal Topic of Suzhou Institute of Industrial Technology:Design and Optimization of Digital Salary System for Intelligent Technology Enterprises(Project No.:SIITHT2024006078)。
文摘Enterprises are facing problems such as the dynamic matching of talents and strategies,and the construction of organizational resilience.Based on this,this paper deeply explores the significance of the research on the“Double Helix”model of strategic human resource management in the VUCA era and the practical construction of the“Double Helix”model:the implementation path of key dimensions,aiming to achieve the coordinated progress of the two through strategies such as improving talent density,forging organizational resilience,and promoting the coordinated integration mechanism of the Double Helix,so as to provide scientific human resource management strategies for enterprises,help enterprises enhance their competitiveness in a complex and changeable environment,and achieve sustainable development.
基金supported by the National Key R&D Project from Ministry of Science and Technology of China(Grant No.2022YFA1203100)the National Natural Science Foundation of China(Grant No.52350088)+1 种基金the Department of Science and Technology of Jiangsu Province(Grant No.BK20220032)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX241797)。
文摘The experimental realization of observable phonon angular momentum(PAM)in feasible systems using relatively simple methods remains a critical challenge.Motivated by the chiral-induced spin selectivity effect,this study explores the generation of PAM during the transport of electrically driven polarons along a singlestranded helix structure.We demonstrate that the motion of a polaron under an applied electric field inherently induces a finite PAM,exhibiting drift-locked behavior between the PAM and the polaron.By analyzing the time evolution of PAM distribution at each site,we identify the observed PAM as a natural consequence of coherent superposition between lattice waves,in which the chiral structure selectively determines the direction of induced PAM.Furthermore,we examine the roles of two types of electron-phonon interactions and structural periodicity in modulating PAM.These findings highlight the potential of chiral molecules as platforms for PAM generation and offer new insights into developing phonon-spin-based devices for information processing and transmission.
基金supported by Zhejiang Provincial Natural Science Foundation of China(Grant No.LR25A040004)。
文摘Recent theoretical work has predicted the existence of a“dipole spiral”structure in strained freestanding membranes of PbTiO_(3),suggesting a potential route to enhanced electromechanical responses[Phys.Rev.Lett.133046802(2024)].However,its microscopic nature,energetic landscape,and electronic properties remain largely unexplored from a first-principles perspective.Here,using density functional theory on PbTiO3 under biaxial tensile strain,we identify a novel form of polar order:a chiral,non-collinear ferroelectric double helix.We find that two distinct,intertwined polarization helices are formed by the local Pb-O and Ti-O dipoles,reminiscent of DNA.This topology is stabilized by a collective helical twisting of the encompassing oxygen cages(the polyhedra for both Pb and Ti cations),which gives rise to an electric Dzyaloshinskii–Moriya-like interaction.The resulting structure,which can be conceptualized as a“self-moiré”crystal,exhibits two coupled functionalities.First,it possesses a rotational pseudo-zero-energy mode that underpins a giant piezoelectric response(e_(33)≈16C/m^(2)).Second,the long-period potential reconstructs the electronic band structure,leading to a multi-valley electronic topology at the valence band edge.Our work establishes a physical route to designing complex chiral order that supports both giant electromechanical coupling and multi-valley electronics.
基金The National Natural Science Foundation of China (No.50976022)the National Key Technology R&D Program of China during the 11th Five-Year Plan Period (No.2008BAJ12B02)
文摘The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid in the shell-side channel is focused on. The results on meridian planes indicate that in the shell-side channel, the center part of fluid has an outward tendency because of the centrifugal force, and the peripheral region fluid has an inward tendency under the centripetal force. So in a spiral cycle, the fluid is divided into the upper and lower beams of streamlines, at the same time the Dean vortices are formed near the left baffle, and then the fluid turns to centripetal flow near the right baffle. Finally the two beams of streamlines merge in the main flow. The results of a number of parallel slices between two parallel baffles with the same sector in a swirl cycle also show the existence of the secondary flow and some backward flows at the V-gaps of the adjacent baffles. The secondary flows have a positive effect on mixing fluid by promoting the momentum and mass exchange between fluid particles near the tube wall and in the main stream, and thus they will enhance the heat transfer of the helix heat exchanger.
文摘An integrated dynamic model considering the influence of the helix angle is developed through dividing the cutting process into three cutting processes： uninterrupted, entry, and exit cutting processes. The semi-discretized technique is used to approximate the finite dimensional Floquet transition matrix of the dynamic control equation to determine the stability of milling process. The stability charts for helix mills are obtained. Results show that the helix angle plays an important role in the stability of milling process. The stability regions with helix angle become larger than those without helix angle. Some ＂islands＂ are presented in the stability charts, and ＂island＂ locations are determined by the relation between the axial depth of cut and the helix pitch. The ＂islands＂ are connected by the ＂bridge＂ by the effects of entry and exit cutting processes. The theoretical results are validated by milling experiments.
