Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or ...Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.展开更多
Objective: To study the characteristics of pulse tracings in CHD, and objectively evaluate the significance of pulse signal in diagnosis and appreciation of therapeutic effect in patients with coronary heart disease(C...Objective: To study the characteristics of pulse tracings in CHD, and objectively evaluate the significance of pulse signal in diagnosis and appreciation of therapeutic effect in patients with coronary heart disease(CHD), and accordingly provide with theoretic proofs for developing non-invasive technique of pulse diagnosis. Methods: By using the pulse detection system, pulse graphs in CHD patients, patients without CHD and "health" adults were collected and compared. Then characters of the pulse signal were analyzed with Hilbert-Huang transformation routine (HHT) and time-domain method respectively. Results: There existed characteristic change in pulse graph in CHD. ① h1,h3,h4,h3/h1,t,t5/t4 in time domain parameters of pulse graph increased and w1 was widened. ② 44% of C2 wave in HHT display showed chaotic and disorderly wave and irregularly wave amplitude in CHD. And 72% of C5 Wave exhibited in irregular wave with average wave amplitude over 10 gram-forces. These changes were significantly different from health adults. Conclusion: Characteristic wave of pulse graph extracted with methods of time domain or HHT routine might be considered as proofs for diagnosis and differentiation in CHD. Our researches prognosticate that pulse diagnosis can be used as an ancillary determination in occurrence of CHD for reasons of the advantage of convenient operation and non-invasion.展开更多
In this paper, a non-Newtonian third-grade blood in coronary and femoral arteries is simulated analytically and numerically. The blood is considered as the third- grade non-Newtonian fluid under the periodic body acce...In this paper, a non-Newtonian third-grade blood in coronary and femoral arteries is simulated analytically and numerically. The blood is considered as the third- grade non-Newtonian fluid under the periodic body acceleration motion and the pulsatile pressure gradient. The hybrid multi-step differential transformation method （Hybrid-Ms- DTM） and the Crank-Nicholson method （CNM） are used to solve the partial differential equation （PDE）, and a good agreement between them is observed in the results. The effects of the some physical parameters such as the amplitude, the lead angle, and the body acceleration frequency on the velocity and shear stress profiles are considered. The results show that increasing the amplitude, Ag, and reducing the lead angle of body acceleration, 9, make higher velocity profiles on the center line of both arteries. Also, the maximum wall shear stress increases when Ag increases.展开更多
In this short note we discuss the GM property of some special linear transformation pairs over infinite-dimensional vector spaces. In particular, it is proved that if R =- End（VD） is the endomorphism ring of an infi...In this short note we discuss the GM property of some special linear transformation pairs over infinite-dimensional vector spaces. In particular, it is proved that if R =- End（VD） is the endomorphism ring of an infinite-dimensional right vector space V over a division ring D with IC（D）I 〉 3 and g e R, then （a0q-alg, 9） is a GM pair for any ao, ale C（D）. Furthermore, two existing results are obtained as immediate consequences.展开更多
Objective: this paper mainly analyzes the correlation between IVIM imaging technology and the transformation of hemorrhage after recanalization treatment of acute ischemic stroke. Methods: 60 patients with acute ische...Objective: this paper mainly analyzes the correlation between IVIM imaging technology and the transformation of hemorrhage after recanalization treatment of acute ischemic stroke. Methods: 60 patients with acute ischemic stroke and 60 patients admitted to our hospital from December 2018 to January 2020 were selected. The patients were scanned by magnetic resonance multi-b-value diffusion weighted imaging, and then the image area diffusion system of the patients' cerebral infarction area and the relative values of various parameters were calculated by IVIM imaging technology. Results: the situation of patients with acute ischemic stroke was significantly improved after vascular recanalization treatment, and there was significant difference between the two sides (P < 0.05). Conclusion: the prediction of IVIM imaging technology in the treatment of patients with acute ischemic stroke is helpful for the treatment of relevant parameters in the area of cerebral infarction, and can also provide accurate basis for relevant values, which is worthy of clinical promotion.展开更多
Precise control over light's spatial and polarization characteristics is essential for advanced photonic systems,yet most conventional approaches are constrained to local, contact-based manipulation at physical in...Precise control over light's spatial and polarization characteristics is essential for advanced photonic systems,yet most conventional approaches are constrained to local, contact-based manipulation at physical interfaces.To overcome these constraints, here we introduce a fundamentally new framework for action-at-a-distance polarization control using virtual polarization elements(VPEs). VPEs apply prescribed local Jones matrix transformations between an input field at the modulation plane and an output field at a remote, contactless free-space plane,enabling programmable polarization operations without local material interaction. We demonstrate this concept using metasurface-based VPEs that realize diverse functionalities: single-function VPEs implementing circular polarizer, linear polarizer, half-wave plate, and quarter-wave plate operations;a multi-function VPE simultaneously encoding spatially distinct Jones matrices with arbitrary relative phase differences;and vortex wave plate configurations for generating vector vortex beams. Furthermore, we extend the VPE platform to synthesize Stokes skyrmions-topologically nontrivial vectorial fields-on a remote plane, including multi-skyrmion integration and polarization-controlled switching. By decoupling the modulation and target planes, VPEs open new opportunities for remote polarization shaping, non-invasive beam engineering, and topological light field synthesis.展开更多
Introduction Doris Lessing has already been recognized as one of the greatest writers in this age,and she won Nobel Prize in Literature in 2007.She is regarded as"the grandmother of the literary circles"and ...Introduction Doris Lessing has already been recognized as one of the greatest writers in this age,and she won Nobel Prize in Literature in 2007.She is regarded as"the grandmother of the literary circles"and the ivy tree of the literary circles"[1]As a prolific and classic writer in the 20th century,she has published twenty-five novels,fifteen volumes of short story,seven works of nonfiction,five plays,a volume ofpoetry and her two autobiographies.Some important political movements andacademic thoughts in the 20th century more or less can be found in her works.展开更多
基金supported by the National Natural Science Foundation of China(11032009 and 11272236)
文摘Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.
基金The National Basic Research Program (973 Program)grant number: 2003CB517108
文摘Objective: To study the characteristics of pulse tracings in CHD, and objectively evaluate the significance of pulse signal in diagnosis and appreciation of therapeutic effect in patients with coronary heart disease(CHD), and accordingly provide with theoretic proofs for developing non-invasive technique of pulse diagnosis. Methods: By using the pulse detection system, pulse graphs in CHD patients, patients without CHD and "health" adults were collected and compared. Then characters of the pulse signal were analyzed with Hilbert-Huang transformation routine (HHT) and time-domain method respectively. Results: There existed characteristic change in pulse graph in CHD. ① h1,h3,h4,h3/h1,t,t5/t4 in time domain parameters of pulse graph increased and w1 was widened. ② 44% of C2 wave in HHT display showed chaotic and disorderly wave and irregularly wave amplitude in CHD. And 72% of C5 Wave exhibited in irregular wave with average wave amplitude over 10 gram-forces. These changes were significantly different from health adults. Conclusion: Characteristic wave of pulse graph extracted with methods of time domain or HHT routine might be considered as proofs for diagnosis and differentiation in CHD. Our researches prognosticate that pulse diagnosis can be used as an ancillary determination in occurrence of CHD for reasons of the advantage of convenient operation and non-invasion.
文摘In this paper, a non-Newtonian third-grade blood in coronary and femoral arteries is simulated analytically and numerically. The blood is considered as the third- grade non-Newtonian fluid under the periodic body acceleration motion and the pulsatile pressure gradient. The hybrid multi-step differential transformation method （Hybrid-Ms- DTM） and the Crank-Nicholson method （CNM） are used to solve the partial differential equation （PDE）, and a good agreement between them is observed in the results. The effects of the some physical parameters such as the amplitude, the lead angle, and the body acceleration frequency on the velocity and shear stress profiles are considered. The results show that increasing the amplitude, Ag, and reducing the lead angle of body acceleration, 9, make higher velocity profiles on the center line of both arteries. Also, the maximum wall shear stress increases when Ag increases.
文摘In this short note we discuss the GM property of some special linear transformation pairs over infinite-dimensional vector spaces. In particular, it is proved that if R =- End（VD） is the endomorphism ring of an infinite-dimensional right vector space V over a division ring D with IC（D）I 〉 3 and g e R, then （a0q-alg, 9） is a GM pair for any ao, ale C（D）. Furthermore, two existing results are obtained as immediate consequences.
文摘Objective: this paper mainly analyzes the correlation between IVIM imaging technology and the transformation of hemorrhage after recanalization treatment of acute ischemic stroke. Methods: 60 patients with acute ischemic stroke and 60 patients admitted to our hospital from December 2018 to January 2020 were selected. The patients were scanned by magnetic resonance multi-b-value diffusion weighted imaging, and then the image area diffusion system of the patients' cerebral infarction area and the relative values of various parameters were calculated by IVIM imaging technology. Results: the situation of patients with acute ischemic stroke was significantly improved after vascular recanalization treatment, and there was significant difference between the two sides (P < 0.05). Conclusion: the prediction of IVIM imaging technology in the treatment of patients with acute ischemic stroke is helpful for the treatment of relevant parameters in the area of cerebral infarction, and can also provide accurate basis for relevant values, which is worthy of clinical promotion.
基金Basic and Applied Basic Research Foundation of Guangdong Province(2021A1515011198).
文摘Precise control over light's spatial and polarization characteristics is essential for advanced photonic systems,yet most conventional approaches are constrained to local, contact-based manipulation at physical interfaces.To overcome these constraints, here we introduce a fundamentally new framework for action-at-a-distance polarization control using virtual polarization elements(VPEs). VPEs apply prescribed local Jones matrix transformations between an input field at the modulation plane and an output field at a remote, contactless free-space plane,enabling programmable polarization operations without local material interaction. We demonstrate this concept using metasurface-based VPEs that realize diverse functionalities: single-function VPEs implementing circular polarizer, linear polarizer, half-wave plate, and quarter-wave plate operations;a multi-function VPE simultaneously encoding spatially distinct Jones matrices with arbitrary relative phase differences;and vortex wave plate configurations for generating vector vortex beams. Furthermore, we extend the VPE platform to synthesize Stokes skyrmions-topologically nontrivial vectorial fields-on a remote plane, including multi-skyrmion integration and polarization-controlled switching. By decoupling the modulation and target planes, VPEs open new opportunities for remote polarization shaping, non-invasive beam engineering, and topological light field synthesis.
基金This study was undertaken under a grant from the foundation of the school of Foreign Languages in Economics and Trade,Southwestern University of Finance and Economics,Chia(Grant No.FLS09002)he foundation of Foreign Language and Literature Research Institution of Sichuan,the Research Foundation of Education Bureau of Sichuan Province,China(Grant No.SCWY13-20)
文摘Introduction Doris Lessing has already been recognized as one of the greatest writers in this age,and she won Nobel Prize in Literature in 2007.She is regarded as"the grandmother of the literary circles"and the ivy tree of the literary circles"[1]As a prolific and classic writer in the 20th century,she has published twenty-five novels,fifteen volumes of short story,seven works of nonfiction,five plays,a volume ofpoetry and her two autobiographies.Some important political movements andacademic thoughts in the 20th century more or less can be found in her works.
