A thin metallic wire loop of arbitrary curvature is rotated with respect to an arbitrary axis of its plane. The device is excited by an electric dipole of infinite length and constant current. The resistance of the lo...A thin metallic wire loop of arbitrary curvature is rotated with respect to an arbitrary axis of its plane. The device is excited by an electric dipole of infinite length and constant current. The resistance of the loop is computed rigorously as function of the position of the source. In this way, the induced voltage along the wire, under any kind of axial excitation, is given in the form of a superposition integral. The measured response is represented for various shapes of the coil, with respect to the time, the rotation angle and the position of the source. These diagrams lead to several technically applicable conclusions which are presented, discussed and justified.展开更多
The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been studied.Numerical computation of the wave displacement field is carried out on and nea...The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been studied.Numerical computation of the wave displacement field is carried out on and near the canyon surfaces using weighted-residuals(moment method).The wave displacement fields are computed by the residual method for the cases of elliptic,circular,rounded-rectangular and flat-elliptic canyons,The analysis demonstrates that the resulting surface displacement depends,as in similar previous analyses,on several factors including,but not limited,to the angle of the wedge,the geometry of the vertex,the frequencies of the incident waves,the angles of incidence,and the material properties of the media.The analysis provides intriguing results that help to explain geophysical observations regarding the amplification of seismic energy as a function of site conditions.展开更多
The electromagnetic wave enhanced transmission(ET)through the sub-wavelength aperture was an unconventional physical phenomenon with great application potential.It was important to find a general design method which c...The electromagnetic wave enhanced transmission(ET)through the sub-wavelength aperture was an unconventional physical phenomenon with great application potential.It was important to find a general design method which can realize efficient ET for arbitrary-shaped apertures.For achieving ET with maximum efficiency at specific frequency through arbitrary-shaped subwavelength aperture,a topology optimization method for designing metamaterials(MTM)microstructure was proposed in this study.The MTM was employed and inserted vertically in the aperture.The description function for the arbitrary shape of the aperture was established.The optimization model was founded to search the optimal MTM microstructure for maximum enhanced power transmission through the aperture at the demanded frequency.Several MTM microstructures for ET through the apertures with different shapes at the demanded frequency were designed as examples.The simulation and experimental results validate the feasibility of the method.The regularity of the optimal ET microstructures and their advantages over the existing configurations were discussed.展开更多
目的探讨腔镜下保留乳头乳晕复合体(NAC)的腺体切除术复合假体+Ti-Loop补片乳房重建治疗乳腺癌(BC)的效果及对术后并发症的影响。方法选取行BC根治术患者162例,随机分为对照组和研究组,每组81例。对照组予以腔镜下保留NAC的腺体切除术...目的探讨腔镜下保留乳头乳晕复合体(NAC)的腺体切除术复合假体+Ti-Loop补片乳房重建治疗乳腺癌(BC)的效果及对术后并发症的影响。方法选取行BC根治术患者162例,随机分为对照组和研究组,每组81例。对照组予以腔镜下保留NAC的腺体切除术复合即刻假体乳房重建治疗,研究组予以腔镜下保留NAC的腺体切除术复合假体+Ti-Loop补片乳房重建治疗。比较2组手术时间、术中出血量、术后引流时间、开始新辅助化疗时间、术后首次下床活动时间、术后24 h视觉模拟评分法(VAS)评分、住院时间和手术前后乳房美观度评分、自尊量表(SES)评分、生活质量综合评定问卷(GQOLI-74)评分、焦虑自评量表(SAS)评分、抑郁自评量表(SDS)评分及术后并发症、复发、转移和生存情况。结果研究组手术时间长于对照组,但术后首次下床活动时间、住院时间短于对照组,术后24 h VAS评分低于对照组,差异有统计学意义(P<0.05)。术后1周~6个月,研究组BC患者美观度评分高于对照组;术后6个月,研究组SES评分、GQOLI-74评分均高于对照组,SAS评分、SDS评分均低于对照组;研究组皮下积液、切口坏死、上肢水肿和乳头坏死发生率低于对照组,差异有统计学意义(P<0.05)。2组术后随访期间肿瘤局部复发、病死率及远处转移发生率差异无统计学意义(P>0.05)。结论腔镜下保留NAC的腺体切除术复合假体+Ti-Loop补片乳房重建治疗BC手术效果较好,可有效降低术后并发症发生率,安全性好。展开更多
This paper is concerned with event-triggered control of discrete-time systems with or without input saturation.First,an accumulative-error-based event-triggered scheme is devised for control updates.When the accumulat...This paper is concerned with event-triggered control of discrete-time systems with or without input saturation.First,an accumulative-error-based event-triggered scheme is devised for control updates.When the accumulated error between the current state and the latest control update exceeds a certain threshold,an event is triggered.Such a scheme can ensure the event-generator works at a relatively low rate rather than falls into hibernation especially after the system steps into its steady state.Second,the looped functional method for continuous-time systems is extended to discrete-time systems.By introducing an innovative looped functional that links the event-triggered scheme,some sufficient conditions for the co-design of control gain and event-triggered parameters are obtained in terms of linear matrix inequalities with a couple of tuning parameters.Then,the proposed method is applied to discrete-time systems with input saturation.As a result,both suitable control gains and event-triggered parameters are also co-designed to ensure the system trajectories converge to the region of attraction.Finally,an unstable reactor system and an inverted pendulum system are given to show the effectiveness of the proposed method.展开更多
The reaction characteristics of calcium-based materials during calcium looping(CaL)process are pivotal in the efficiency of CaL thermochemical energy storage(TCES)and CO_(2)capture systems.Currently,metal oxide doping...The reaction characteristics of calcium-based materials during calcium looping(CaL)process are pivotal in the efficiency of CaL thermochemical energy storage(TCES)and CO_(2)capture systems.Currently,metal oxide doping is the primary method to enhance the reaction characteristics of calcium-based materials over multiple cycles.In particular,co-doping with variable-valence metal oxides(VVMOs)can effectively increase the oxygen vacancy content in calcium-based materials,significantly improving their cyclic reaction characteristics.However,there are so numerous VVMOs co-doping schemes that the experimental screening process is complex,consuming considerable time and economic costs.Density functional theory(DFT)calculations have been widely used to reveal the impact of metal oxide doping on the cyclic reaction characteristics of calcium-based materials,with calculation results showing good agreement with experimental conclusions.Nevertheless,there is still a lack of research on utilizing DFT to screen calcium-based materials,and a systematic research methodology has not yet been established.In this study,a systematic DFT-based screening methodology for calcium-based materials was proposed.A series of key parameters for DFT calculations including CO_(2)adsorption energy,oxygen vacancy formation energy,and sintering resistance were proposed.Furthermore,a preliminary mathematical model to predict the CaL TCES and CO_(2)capture performance of calcium-based materials was introduced.The aforementioned DFT method was employed to screen for VVMOs co-doped calcium-based materials.The results revealed that Mn and Ce co-doped calcium-based materials exhibited superior DFT-predicted reaction characteristics.These DFT predictions were validated through experimental assessments of cyclic thermochemical energy storage,CO_(2)capture,and relevant characterization.The outcomes demonstrate a high degree of consistency among DFT-based predictions,experimental results,and characterization.Hence,the DFT-based screening methodology for calcium-based materials proposed herein is a viable solution,poised to offer theoretical insights for the efficient design of calcium-based materials.展开更多
As space technology advances,thermal control systems must effectively collect and dissipate heat from distributed,multi-source environments.Loop heat pipe is a highly reliable two-phase heat transfer component,but it ...As space technology advances,thermal control systems must effectively collect and dissipate heat from distributed,multi-source environments.Loop heat pipe is a highly reliable two-phase heat transfer component,but it has several limitations when addressing multi-source heat dissipation.Inspired by the transport and heat dissipation system of plants,large trees achieve stable and efficient liquid supply under the influence of two driving forces:capillary force during transpiration in the leaves(pull)and root pressure generated by osmotic pressure in the roots(push).The root pressure provides an effective liquid supply with a driving force exceeding 2 MPa,far greater than the driving force in conventional capillary-pumped two-phase loops.Research has shown that osmotic heat pipes offer a powerful driving force,and combining osmotic pressure with capillary force has significant advantages.Therefore,this paper designs a multi-evaporator,dual-drive two-phase loop,using both osmotic pressure and capillary force to solve the multi-source heat dissipation challenge.First,a transmembrane water flux model for the osmotic pressure-driven device was established to predict the maximum heat transfer capacity of the dual-drive two-phase loop.Then,an experimental setup for a multi-evaporator“osmotic pressure+capillary force”dual-drive two-phase loop was constructed,capable of transferring at least 235 W of power under a reverse gravity condition of 20 m.The study also analyzed the effects of reverse gravity height,heat load distribution among the three evaporators,startup sequence,and varying branch resistances on the performance of the dual-drive two-phase loop.展开更多
【目的】掌握骨唇黄河鱼(Chuanchia labiosa)其野生种质资源现状,了解其系统发育关系和进化状况。【方法】对野外采样的106尾骨唇黄河鱼进行mt DNA Cytb,COX1和D-Loop基因多样性对比。【结果】结果表明9个裂腹鱼亚科群体系统发育进化树...【目的】掌握骨唇黄河鱼(Chuanchia labiosa)其野生种质资源现状,了解其系统发育关系和进化状况。【方法】对野外采样的106尾骨唇黄河鱼进行mt DNA Cytb,COX1和D-Loop基因多样性对比。【结果】结果表明9个裂腹鱼亚科群体系统发育进化树分为3大支,Network与系统发育树结果基本一致。骨唇黄河鱼Tajima’sD和Fu’sFs检验及错配分布分析均表明其经历过种群扩张,不同种群分离的时间可能与青藏高原地质运动有关。【结论】骨唇黄河鱼的遗传多样性相对较低,呈高单倍型多样度和低核苷酸多样度的特点。展开更多
With the development of space-based remote sensing and deep space exploration technology,higher standards for temperature stability and uniformity of payloads have been proposed to spacecraft thermal control systems.A...With the development of space-based remote sensing and deep space exploration technology,higher standards for temperature stability and uniformity of payloads have been proposed to spacecraft thermal control systems.As an efficient two-phase heat transfer device with active temperature control capabilities,the loop heat pipe(LHP)can be widely applied in spacecraft thermal control systems to achieve reliable temperature control under various operating modes and complex space thermal environments.This paper analyzes the fundamental theories of thermal switch-controlled,reservoir temperature-controlled,and bypass valve-controlled LHPs.The focus is on the theories and methods of achieving high-precision and high-reliability temperature control via active reservoir temperature control.Novel control techniques in recent years,such as non-condensable gas(NCG)control with a temperature stability of 0.01℃ ,are also briefly introduced as promising approaches to improve LHP performance.The on-orbit performance and characteristics of various LHP temperature control methods are provided and ranked in terms of control precision,energy consumption,complexity,and weight.Thermoelectric cooler(TEC)/electrical heater,as the foundation of reservoir temperature control,can achieve a temperature stability of in space applications under±0.2℃ a wide range of heat load.Microgravity model,control strategy,and operating mode conversion are three optimization directions that would hopefully further expand the application scenario of reservoir temperature control.Specific design principles and challenges for corresponding directions are summarized as guidance for researchers.展开更多
文摘A thin metallic wire loop of arbitrary curvature is rotated with respect to an arbitrary axis of its plane. The device is excited by an electric dipole of infinite length and constant current. The resistance of the loop is computed rigorously as function of the position of the source. In this way, the induced voltage along the wire, under any kind of axial excitation, is given in the form of a superposition integral. The measured response is represented for various shapes of the coil, with respect to the time, the rotation angle and the position of the source. These diagrams lead to several technically applicable conclusions which are presented, discussed and justified.
文摘The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been studied.Numerical computation of the wave displacement field is carried out on and near the canyon surfaces using weighted-residuals(moment method).The wave displacement fields are computed by the residual method for the cases of elliptic,circular,rounded-rectangular and flat-elliptic canyons,The analysis demonstrates that the resulting surface displacement depends,as in similar previous analyses,on several factors including,but not limited,to the angle of the wedge,the geometry of the vertex,the frequencies of the incident waves,the angles of incidence,and the material properties of the media.The analysis provides intriguing results that help to explain geophysical observations regarding the amplification of seismic energy as a function of site conditions.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1808215)the Natural Science Foundation of Liaoning Province,China(Grant No.20180540082)the Science and Technology Program of Shenzhen(Grant No.JSGG 20200102155001779).
文摘The electromagnetic wave enhanced transmission(ET)through the sub-wavelength aperture was an unconventional physical phenomenon with great application potential.It was important to find a general design method which can realize efficient ET for arbitrary-shaped apertures.For achieving ET with maximum efficiency at specific frequency through arbitrary-shaped subwavelength aperture,a topology optimization method for designing metamaterials(MTM)microstructure was proposed in this study.The MTM was employed and inserted vertically in the aperture.The description function for the arbitrary shape of the aperture was established.The optimization model was founded to search the optimal MTM microstructure for maximum enhanced power transmission through the aperture at the demanded frequency.Several MTM microstructures for ET through the apertures with different shapes at the demanded frequency were designed as examples.The simulation and experimental results validate the feasibility of the method.The regularity of the optimal ET microstructures and their advantages over the existing configurations were discussed.
文摘目的探讨腔镜下保留乳头乳晕复合体(NAC)的腺体切除术复合假体+Ti-Loop补片乳房重建治疗乳腺癌(BC)的效果及对术后并发症的影响。方法选取行BC根治术患者162例,随机分为对照组和研究组,每组81例。对照组予以腔镜下保留NAC的腺体切除术复合即刻假体乳房重建治疗,研究组予以腔镜下保留NAC的腺体切除术复合假体+Ti-Loop补片乳房重建治疗。比较2组手术时间、术中出血量、术后引流时间、开始新辅助化疗时间、术后首次下床活动时间、术后24 h视觉模拟评分法(VAS)评分、住院时间和手术前后乳房美观度评分、自尊量表(SES)评分、生活质量综合评定问卷(GQOLI-74)评分、焦虑自评量表(SAS)评分、抑郁自评量表(SDS)评分及术后并发症、复发、转移和生存情况。结果研究组手术时间长于对照组,但术后首次下床活动时间、住院时间短于对照组,术后24 h VAS评分低于对照组,差异有统计学意义(P<0.05)。术后1周~6个月,研究组BC患者美观度评分高于对照组;术后6个月,研究组SES评分、GQOLI-74评分均高于对照组,SAS评分、SDS评分均低于对照组;研究组皮下积液、切口坏死、上肢水肿和乳头坏死发生率低于对照组,差异有统计学意义(P<0.05)。2组术后随访期间肿瘤局部复发、病死率及远处转移发生率差异无统计学意义(P>0.05)。结论腔镜下保留NAC的腺体切除术复合假体+Ti-Loop补片乳房重建治疗BC手术效果较好,可有效降低术后并发症发生率,安全性好。
基金supported in part by the National Natural Science Foundation of China(62473221)the Natural Science Foundation of Shandong Province,China(ZR2024MF006)Qingdao Natural Science Foundation(24-4-4-zrjj-165-jch)。
文摘This paper is concerned with event-triggered control of discrete-time systems with or without input saturation.First,an accumulative-error-based event-triggered scheme is devised for control updates.When the accumulated error between the current state and the latest control update exceeds a certain threshold,an event is triggered.Such a scheme can ensure the event-generator works at a relatively low rate rather than falls into hibernation especially after the system steps into its steady state.Second,the looped functional method for continuous-time systems is extended to discrete-time systems.By introducing an innovative looped functional that links the event-triggered scheme,some sufficient conditions for the co-design of control gain and event-triggered parameters are obtained in terms of linear matrix inequalities with a couple of tuning parameters.Then,the proposed method is applied to discrete-time systems with input saturation.As a result,both suitable control gains and event-triggered parameters are also co-designed to ensure the system trajectories converge to the region of attraction.Finally,an unstable reactor system and an inverted pendulum system are given to show the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(52276204 and U22A20435)。
文摘The reaction characteristics of calcium-based materials during calcium looping(CaL)process are pivotal in the efficiency of CaL thermochemical energy storage(TCES)and CO_(2)capture systems.Currently,metal oxide doping is the primary method to enhance the reaction characteristics of calcium-based materials over multiple cycles.In particular,co-doping with variable-valence metal oxides(VVMOs)can effectively increase the oxygen vacancy content in calcium-based materials,significantly improving their cyclic reaction characteristics.However,there are so numerous VVMOs co-doping schemes that the experimental screening process is complex,consuming considerable time and economic costs.Density functional theory(DFT)calculations have been widely used to reveal the impact of metal oxide doping on the cyclic reaction characteristics of calcium-based materials,with calculation results showing good agreement with experimental conclusions.Nevertheless,there is still a lack of research on utilizing DFT to screen calcium-based materials,and a systematic research methodology has not yet been established.In this study,a systematic DFT-based screening methodology for calcium-based materials was proposed.A series of key parameters for DFT calculations including CO_(2)adsorption energy,oxygen vacancy formation energy,and sintering resistance were proposed.Furthermore,a preliminary mathematical model to predict the CaL TCES and CO_(2)capture performance of calcium-based materials was introduced.The aforementioned DFT method was employed to screen for VVMOs co-doped calcium-based materials.The results revealed that Mn and Ce co-doped calcium-based materials exhibited superior DFT-predicted reaction characteristics.These DFT predictions were validated through experimental assessments of cyclic thermochemical energy storage,CO_(2)capture,and relevant characterization.The outcomes demonstrate a high degree of consistency among DFT-based predictions,experimental results,and characterization.Hence,the DFT-based screening methodology for calcium-based materials proposed herein is a viable solution,poised to offer theoretical insights for the efficient design of calcium-based materials.
基金Science Foundation for Distinguished Young Scholars 2020-JCJQ-ZQ-042 Intelligent and Bionic Spacecraft Thermal Control Technology Inspired by Tree Sap Transport Principle.
文摘As space technology advances,thermal control systems must effectively collect and dissipate heat from distributed,multi-source environments.Loop heat pipe is a highly reliable two-phase heat transfer component,but it has several limitations when addressing multi-source heat dissipation.Inspired by the transport and heat dissipation system of plants,large trees achieve stable and efficient liquid supply under the influence of two driving forces:capillary force during transpiration in the leaves(pull)and root pressure generated by osmotic pressure in the roots(push).The root pressure provides an effective liquid supply with a driving force exceeding 2 MPa,far greater than the driving force in conventional capillary-pumped two-phase loops.Research has shown that osmotic heat pipes offer a powerful driving force,and combining osmotic pressure with capillary force has significant advantages.Therefore,this paper designs a multi-evaporator,dual-drive two-phase loop,using both osmotic pressure and capillary force to solve the multi-source heat dissipation challenge.First,a transmembrane water flux model for the osmotic pressure-driven device was established to predict the maximum heat transfer capacity of the dual-drive two-phase loop.Then,an experimental setup for a multi-evaporator“osmotic pressure+capillary force”dual-drive two-phase loop was constructed,capable of transferring at least 235 W of power under a reverse gravity condition of 20 m.The study also analyzed the effects of reverse gravity height,heat load distribution among the three evaporators,startup sequence,and varying branch resistances on the performance of the dual-drive two-phase loop.
文摘【目的】掌握骨唇黄河鱼(Chuanchia labiosa)其野生种质资源现状,了解其系统发育关系和进化状况。【方法】对野外采样的106尾骨唇黄河鱼进行mt DNA Cytb,COX1和D-Loop基因多样性对比。【结果】结果表明9个裂腹鱼亚科群体系统发育进化树分为3大支,Network与系统发育树结果基本一致。骨唇黄河鱼Tajima’sD和Fu’sFs检验及错配分布分析均表明其经历过种群扩张,不同种群分离的时间可能与青藏高原地质运动有关。【结论】骨唇黄河鱼的遗传多样性相对较低,呈高单倍型多样度和低核苷酸多样度的特点。
基金funded by National Outstanding Youth Foundation of China,grant number 2020-JCJQ-ZQ-042.
文摘With the development of space-based remote sensing and deep space exploration technology,higher standards for temperature stability and uniformity of payloads have been proposed to spacecraft thermal control systems.As an efficient two-phase heat transfer device with active temperature control capabilities,the loop heat pipe(LHP)can be widely applied in spacecraft thermal control systems to achieve reliable temperature control under various operating modes and complex space thermal environments.This paper analyzes the fundamental theories of thermal switch-controlled,reservoir temperature-controlled,and bypass valve-controlled LHPs.The focus is on the theories and methods of achieving high-precision and high-reliability temperature control via active reservoir temperature control.Novel control techniques in recent years,such as non-condensable gas(NCG)control with a temperature stability of 0.01℃ ,are also briefly introduced as promising approaches to improve LHP performance.The on-orbit performance and characteristics of various LHP temperature control methods are provided and ranked in terms of control precision,energy consumption,complexity,and weight.Thermoelectric cooler(TEC)/electrical heater,as the foundation of reservoir temperature control,can achieve a temperature stability of in space applications under±0.2℃ a wide range of heat load.Microgravity model,control strategy,and operating mode conversion are three optimization directions that would hopefully further expand the application scenario of reservoir temperature control.Specific design principles and challenges for corresponding directions are summarized as guidance for researchers.
