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Two-Photon Excited State Dynamics of Dark Rydberg and Bright Valence States in Furan
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作者 Jin-You Long Chun-Long Hu Bing Zhang 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第4期26-29,共4页
Two-photon absorption in systems with parity permits access to states that cannot be directly prepared by one-photon absorption. Here we investigate ultrafast internal conversion (IC) dynamics of furan by using this... Two-photon absorption in systems with parity permits access to states that cannot be directly prepared by one-photon absorption. Here we investigate ultrafast internal conversion (IC) dynamics of furan by using this strategy in combination with femtosecond time-resolved photoelectron imaging. The dark Rydberg S1 and bright valence S2 states are simultaneously excited by two photons of 405 nm, and then ionized by two photons of 800nm. The IC from S2 to S1 is clearly observed and extracted from the time dependence of the higher photoelectron kinetic energy (PKE) component. More importantly, the internal conversions to hot So from directly-prepared S1 and secondarily-populated S1 are unambiguously identified by the time-dependence of the lower PKE component. The average lifetime of the S2 and S1 states is measured to be 29 fs. The internal conversions of S2 to S1, S1 to hot So occur on estimated timescales of 15.4 fs and 38 fs, respectively. 展开更多
关键词 SI Two-Photon Excited State Dynamics of Dark Rydberg and Bright Valence states in Furan
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Change of State of a Dynamical Unit in the Transition of Coherence
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作者 杨言晋 杜如海 +2 位作者 王圣军 金涛 屈世显 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第1期18-21,共4页
The change of state of one map in the network of nonlocal coupled logistic maps at the transition of coherence is studied. With the increase of coupling strength, the network dynamics transits from the incoherent stat... The change of state of one map in the network of nonlocal coupled logistic maps at the transition of coherence is studied. With the increase of coupling strength, the network dynamics transits from the incoherent state into the coherent state. In the process, the iteration of the map first changes from chaos to period state, then from periodic to chaotic state again. For the periodic doubling bifurcations, similar to an isolated map, the largest Lyapunov exponent tends to zero from a negative value. However, the states of coupled maps exhibit complex behavior rather than converge to a few fixed values. The behavior brings a new chimera state of coupled logistic maps. The bifurcation diagram is identical to the phase order of maps iterations. For the bifurcation between 1-band and multi-band chaos, the symmetry of chaotic bands emerges and the transition of the order of iteration direction occurs. 展开更多
关键词 net Change of State of a dynamical Unit in the Transition of Coherence
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Resonance Raman Spectroscopic and Theoretical Study of Geometry Distortion of Thiourea in 2^1A State
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作者 张海波 赵彦英 郑旭明 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2012年第1期1-10,I0003,共11页
The A-band resonance Raman spectra of thiourea were obtained in water and acetonitrile solution. B3LYP/6-311++G(3df,3pd) and RCIS/6-311++G(3df,3pd) calculations were done to elucidate the ultraviolet electroni... The A-band resonance Raman spectra of thiourea were obtained in water and acetonitrile solution. B3LYP/6-311++G(3df,3pd) and RCIS/6-311++G(3df,3pd) calculations were done to elucidate the ultraviolet electronic transitions, the distorted geometry structure and the saddle point of thiourea in 21A excited state, respectively. The resonance Raman spectra were assigned. The absorption spectrum and resonance Raman intensities were modeled using Heller's time-dependent wavepacket approach to resonance Raman scattering. The results indicate that largest change in the displacement takes place with the C--S stretch mode u6 (|△|=0.95) and noticeable changes appear in the H5N3H6+H8N4H7 wag v5 (|△|=0.19), NCN symmetric stretch^-C--S stretch+N3H6+H8N4 wag v4 (|△|=0.18), while the moderate intensities of 2-15 and 4-15 are mostly due to the large excited state frequency changes of v15, but not due to its significant change in the normal mode displacement. The mechanism of the appearance of even overtones of the S-CN2 out of plane deformation is explored. The results indicate that a Franck-Condon region saddle point is the driving force for the quadric phonon mechanism within the standard A-term of resonance Raman scattering, which leads to the pyramidalization of the carbon center and the geometry distortion of thiourea molecule in 21A excited state. 展开更多
关键词 THIOUREA Excited state structural dynamics Resonance Raman Timedependent wavepacket approach Density functional theory
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Translation of the contrastive scenes and implication in River snow
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作者 孙琴青 欧丽慧 《Sino-US English Teaching》 2008年第1期76-80,共5页
This paper makes a brief analysis of the scenes and implication of the famous Ancient Chinese poem River snow. It makes a comparison and contrast of the five typical English versions from the perspective of the transl... This paper makes a brief analysis of the scenes and implication of the famous Ancient Chinese poem River snow. It makes a comparison and contrast of the five typical English versions from the perspective of the translation of its static and dynamic states. The paper also discusses the meaning of “du diao han jiang xue”, and how to better translate the key word “diao”. 展开更多
关键词 River snow SCENE static state dynamic state fish alone in the cold river-snow
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Variable dimensional state space based global path planning for mobile robot 被引量:1
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作者 张浩杰 陈慧岩 +6 位作者 姜岩 龚建伟 熊光明 陈慧岩 姜岩 龚建伟 熊光明 《Journal of Beijing Institute of Technology》 EI CAS 2012年第3期328-335,共8页
A variable dimensional state space(VDSS) has been proposed to improve the re-planning time when the robotic systems operate in large unknown environments.VDSS is constructed by uniforming lattice state space and gri... A variable dimensional state space(VDSS) has been proposed to improve the re-planning time when the robotic systems operate in large unknown environments.VDSS is constructed by uniforming lattice state space and grid state space.In VDSS,the lattice state space is only used to construct search space in the local area which is a small circle area near the robot,and grid state space elsewhere.We have tested VDSS with up to 80 indoor and outdoor maps in simulation and on segbot robot platform.Through the simulation and segbot robot experiments,it shows that exploring on VDSS is significantly faster than exploring on lattice state space by Anytime Dynamic A*(AD*) planner and VDSS is feasible to be used on robotic systems. 展开更多
关键词 variable dimensional state space lattice state space Anytime Dynamic A*(AD*) path planning
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THEORETICAL INVESTIGATION ON STATE OF LOAD DISTRIBUTION AMONG CONTACT BEARINGS OF DOUBLE CIRCULAR ARC HELICAL GEARS 被引量:3
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作者 Wu Baolin (Gear Research Institute, Taiyuan University of Technology) 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2000年第2期108-113,共6页
A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced... A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced distribution based on the theory of W-N gears. The changing situations of load distribution among contact bearings of the gears influenced by main issues are analyzed by a series of parametric studies. 展开更多
关键词 Double circular are belical gears State of load distribution Factor of load distribution Dynamic analysis
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Mathematical analysis of organic-pass transistor using pseudo-p-OTFTs
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作者 Shagun Pal Brijesh Kumar 《Journal of Semiconductors》 EI CAS CSCD 2020年第6期71-77,共7页
Steady state behavior analysis of organic thin film transistor(OTFTs)has been thoroughly researched in the past few decades.Yet,this static logic analysis has drawbacks of high power dissipation and high power consump... Steady state behavior analysis of organic thin film transistor(OTFTs)has been thoroughly researched in the past few decades.Yet,this static logic analysis has drawbacks of high power dissipation and high power consumption,and a large number of prerequisites in the number of transistors for the digital logic circuit application.Hence,to overcome these basic fundamental drawbacks of static logic,the dynamic logic study of organic thin film transistor has been analyzed in this paper.The fundamental basic of dynamic logic is a pass transistor for which logic high and logic low model is designed at an operating voltage of 5 V and frequency of 5 kHz.Additionally,the novel approach of analytical model for organic pass transistor(OPT)circuit is included and verified using MATLAB.The transient individualities of organic pass transistor OPT are examined through Atlas 2-D numerical device simulator.The reduction in the power dissipation along with additional voltage scaling and reduction in the clock frequency such as pipelining may further enable the applications into more complex VLSI ICs. 展开更多
关键词 organic-pass transistor(OPT) logic high logic low pseudo-p dynamic state analytical model
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Recurrence anomaly of ground water behavior before strong earthquakes in North China
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作者 CAO Xin-lai(曹新来) BIAN Qing-kai(边庆凯) 《Acta Seismologica Sinica(English Edition)》 CSCD 2004年第z1期163-171,共9页
By analyzing the relationship between ground water behavior and strong seismic activity during the past more than 20 years in North China, we have found similar water level descending variation of a part of wells in ... By analyzing the relationship between ground water behavior and strong seismic activity during the past more than 20 years in North China, we have found similar water level descending variation of a part of wells in the short-term stage before several strong earthquakes. The characteristics of anomaly are: at the beginning, water level dropped abruptly or accelerated to drop; then it turned to slow rising with a smaller amplitude than that of descending; earthquakes occurred during the slow-rising process of water level, and at that time or before earthquake occurrence, water level rose with a large amplitude. Among more than 100 wells in North China, the descending anomalies were not recorded for many times, but similar variation processes of water level were noted at different wells before several strong earthquakes, which proves that seismic precursory anomalies of ground water are of certain recurrence features, occurring repeatedly before different strong earthquakes. Therefore, it is necessary to study the genesis of this type of anomaly and its relationship with strong seismic activity. 展开更多
关键词 North China strong earthquake dynamic state of water level short-term stage RECURRENCE
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Photochemistry of Potassium Ferrocyanide and its Reaction with Uridine 5′-monophosphate in Aqueous Solution under Ultraviolet Irradiation
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作者 Song-qiu Yang Yan Zhang Yan-ni Wang 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第5期764-773,I0014-I0022,I0011,I0012,共21页
The photochemical reaction of potassium ferrocyanide(K_(4)Fe(CN)_(6))exhibits excitation wavelength dependence and non-Kasha rule behavior.In this study,the excited-state dynamics of K_(4)Fe(CN)_(6) were studied by tr... The photochemical reaction of potassium ferrocyanide(K_(4)Fe(CN)_(6))exhibits excitation wavelength dependence and non-Kasha rule behavior.In this study,the excited-state dynamics of K_(4)Fe(CN)_(6) were studied by transient absorption spectroscopy.Excited state electron detachment(ESED)and photoaquation reactions were clarified by comparing the results of 260,320,340,and 350 nm excitations.ESED is the path to generate a hydrated electron(e^(−)_(aq)).ESED energy barrier varies with the excited state,and it occurs even at the first singlet excited state(^(1)T_(1g)).The ^(1)T_(1g) state shows∼0.2 ps lifetime and converts into triplet[Fe(CN)_(6)]4−by intersystem crossing.Subsequently,3Fe(CN)_(5)]^(3-)appears after one CN−ligand is ejected.In sequence,H2O attacksFe(CN)_(5)]^(3-)to generate[Fe(CN)_(5)H_(2)O]^(3−)with a time constant of approximately 20 ps.The ^(1)T_(1g) state and e−aq exhibit strong reducing power.The addition of uridine 5′-monophosphate(UMP)to the K_(4)Fe(CN)_(6) solution decrease the yield of e−aq and reduce the lifetimes of the e−aq and ^(1)T_(1g) state.The obtained reaction rate constant of ^(1)T_(1g) state and UMP is 1.7×10^(14)(mol/L)^(−1)·s^(−1),and the e−aq attachment to UMP is∼8×10^(9)(mol/L)^(−1)·s^(−1).Our results indicate that the reductive damage of K_(4)Fe(CN)_(6) solution to nucleic acids under ultraviolet irradiation cannot be neglected. 展开更多
关键词 Ultrafast spectroscopy Photoaquation Electron detachment Excited state dynamics Ferrous hexacyanides
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Ultrafast Excited State Dynamics of Biliverdin Dimethyl Ester Coordinate with Zinc Ions
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作者 Zhuang Chen Yang-yi Liu +1 位作者 Xiao-xiao He Jin-quan Chen 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第1期69-74,I0030-I0033,共10页
As one of the biological endogenous pigments,biliverdin(BV)and its dimethyl ester(BVE)have extremely weak uorescence in solution with quantum yield less than 0.01%.However,the situation reverses with the addition of z... As one of the biological endogenous pigments,biliverdin(BV)and its dimethyl ester(BVE)have extremely weak uorescence in solution with quantum yield less than 0.01%.However,the situation reverses with the addition of zinc ions.The strength for uorescence of BVE-Zn^2+ complex is greatly enhanced and uorescence quantum yield can increase to5%.Herein,we studied ultrafast excited state dynamics of BVE-Zn^2+ complex in ethanol,npropanol,and DMSO solutions in order to reveal the mechanism of uorescence quantum yield enhancement.The results show that BVE can form a stable coordination complex with zinc with 1:1 stoichiometry in solution.BVE is structurally and energetically more stable in the complex.Using picosecond time-resolve uorescence and femtosecond transient absorption spectroscopy,we show that smaller non-radiative rate constant of BVE-Zn^2+ complex in DMSO is the key to increasing its uorescence quantum yield and the excited state decay mechanism is also revealed.These results provide valuable information about the uorescence property change after BVE binding to metal ions and may provide a guidance for the study of phytochromes or other uorescence proteins in which BV/BVE acts as chromophores. 展开更多
关键词 BILIVERDIN ZINC FLUORESCENCE Quantum yield Femtosecond transient absorption Excited state dynamics
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SELECTION OF STATE VARIABLES AND CONSTRUCTION OF STATE EQUATIONS
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作者 胡允祥 《Journal of China Textile University(English Edition)》 EI CAS 1991年第3期65-76,共12页
In modern control engineering and simulations,it is perferable to get the governing equationsby an easier way,so that state equations have been widely used.There are many rules to select statevariables,but the uses of... In modern control engineering and simulations,it is perferable to get the governing equationsby an easier way,so that state equations have been widely used.There are many rules to select statevariables,but the uses of these rules may have different forms of limitations and exceptions,yet afully argumented bond graph can be processed in proper way to select the state variables and toyield the state equations.The state variables are usually related to the energy-storing elements.State equations can easily be derived from bond graph by means of constitutive relations and struc-tural relations. 展开更多
关键词 dynamics state VARIABLES system dynamics bond GRAPH
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Long Chain Fatty Acid Affects Excited State Branching in Bilirubin-Human Serum Protein Complex
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作者 Yang-yi Liu Hai-feng Pan +1 位作者 Jian-hua Xu Jin-quan Chen 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2021年第5期621-627,I0003,共8页
After binding to human serum albumin,bilirubin could undergo photoisomerization and photoinduced cyclization process.The latter process would result the formation of a product,named as lumirubin.These photo induced be... After binding to human serum albumin,bilirubin could undergo photoisomerization and photoinduced cyclization process.The latter process would result the formation of a product,named as lumirubin.These photo induced behaviors are the fundamental ofclinical therapy for neonatal jaundice.Previous studies have reported that the addition of long chain fatty acids is beneficial to the generation of lumirubin,yet no kinetic study has revealed the mechanism behind.In this study,how palmitic acid affects the photochemical reaction process of bilirubin in Human serum albumin(HSA)is studied by using femtosecond transient absorption and fluorescence up-conversion techniques.With the addition of palmitic acid,the excited population of bilirubin prefers to return to its hot ground state(S_(0))through a 4 ps decay channel rather than the intrinsic ultrafast decay pathways(<1 ps).This effect prompts the Z-Z to E-Z isomerization at the S_(0) state and then further increases the production yield of lumirubin.This is the first time to characterize the promoting effect of long chain fatty acid in the process of phototherapy with femtosecond time resolution spectroscopy and the results can provide useful information to benefit the relevant clinical study. 展开更多
关键词 BILIRUBIN Human serum albumin Femtosecond transient absorption Excited state dynamics
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Forecasting the underground waters regime in the pitching aquifers in Huainan mining area
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作者 桂和荣 宋晓梅 《Journal of Coal Science & Engineering(China)》 2001年第1期46-51,共6页
Huainan area is an important coal base of the east of China. In the early part of the 1980s, the study of the underground waters dynamic state in the area was gradually paid close attention to. This paper introduces t... Huainan area is an important coal base of the east of China. In the early part of the 1980s, the study of the underground waters dynamic state in the area was gradually paid close attention to. This paper introduces the observation system of the groundwater dynamic state in the multilayered pitching aquifer, and expounds the hydrogeologic feature and the waterpower relations among aquifers. Furthermore, based on the analysis of the relations of the groundwater dynamic state to surface water, meteoric water and mining shaft outflow rate, this paper establishes main water filled aquifers of mining shaft (C 3-1 ,C 3-2 ,C 3-3 and O 2).In the light of the actual situation of the greatly changing aquifer occurrence and steep dip angle, the “two layer space curved surface seepage model" and the calculating step are all suggested. Since 1991,the groundwater dynamic state of the next year has been predicted (numerical simulation) every year. Contracting with the measured data, we gain a relatively ideal effect. 展开更多
关键词 pitching aquifers water level dynamic state two layer space curve seepage model numerical simulation
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Unraveling Vibrational Wavepacket Dynamics using Femtosecond Ion Yield Spectroscopy and Photoelectron Imaging
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作者 Bing Zhang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2019年第1期35-45,I0001,共12页
Time-resolved photoionization is a powerful experimental approach to unravel the excited state dynamics in isolated polyatomic molecules. Depending on species of the collected signals, different methods can be perform... Time-resolved photoionization is a powerful experimental approach to unravel the excited state dynamics in isolated polyatomic molecules. Depending on species of the collected signals, different methods can be performed: time-resolved ion yield spectroscopy (TR-IYS) and time-resolved photoelectron imaging (TR-PEI). In this review, the essential concepts linking photoionization measurement with electronic structure are presented, together with several important breakthroughs in experimentally distinguishing the oscillating wavepacket motion between different geometries. We illustrate how femtosecond TR-IYS and TR-PEI are employed to visualize the evolution of a coherent vibrational wavepacket on the excited state surface. 展开更多
关键词 Vibrational wavepacket Time-resolved ion yield Photoelectron imaging Excited state dynamics
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Alternation in F-wave parameters of median nerve from unaffected extremity in stroke patients with hemiplegia under dynamic state
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作者 Hang Zhao Yong Lin Wenhua Qi Shuping Yin Jiachun Feng 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第9期806-808,共3页
BACKGROUND: For many years, the extremities of stroke patients are divided into affected side and unaffected side according to clinical symptoms and body signs. Moreover, previous rehabilitation function training is d... BACKGROUND: For many years, the extremities of stroke patients are divided into affected side and unaffected side according to clinical symptoms and body signs. Moreover, previous rehabilitation function training is developed simply aiming to the dysfunction manifested by unaffected extremity. Problems of unaffected extremity are always ignored, such as left- and right- side connection dysfunction, abnormal muscular tension of unaffected side and so on. OBJECTIVE: To observe neurophysiological change characteristics of unaffected extremity of stroke patients with hemiplegia by electromyographical method. DESIGN: Case-control observation. SETTING: First Hospital, Jilin University. PARTICIPANTS: Eighty stroke patients with hemiplegia confirmed by skull CT or MRI, who firstly hospitalized in the Department of Neurology, First Hospital, Jilin University between July 2004 and March 2005, were retrieved. They were scored > 8 points in Glasgow Coma Scale and had stable vital sign. Nineteen normal persons who received healthy examination in the clinic were involved in normal control group. Following the classification criteria of Brunnstrom's Recovery Stages of Stroke (BRSS), 80 stroke patients with hemiplegia were assigned into 3 groups: BRSS Ⅰ-Ⅱ group (n =36), BRSS Ⅲ-Ⅳ group (n =23) and BRSSⅤ-Ⅵ (n =21). METHODS: F-wave parameters of median nerve of unaffected extremity were detected by electromyographical technique. The recording electrode (muscular belly of abductor pollicis brevis) and reference electrode (first finger bone) were connected with grounding electrode. Stimulating electrode was placed in the median part of wrist joint with stimulation intensity of 130% that of threshold stimulation, stimulation frequency of 2 Hz, current pulse width of 0.2 ms, time course of 5 ms and sensitivity of 2 mV. The F-wave of median nerve of affected extremity under the resting stage (static status) and that of unaffected extremity under the maximum resistant contracted state were detected in order. The amplitude and appearance percentage of F wave were recorded. MAIN OUTCOME MEASURES: Comparison of F-wave parameters of median nerve between the unaffected extremity of stroke patients with hemiplegia and the extremity of control subjects under different status. RESULTS: All the patients accomplished the detection, and all of them participated in the final analysis. ①Under dynamic status, the amplitude and appearance percentage of F wave of unaffected extremity of patients in BRSS Ⅲ-Ⅳ group were significantly higher than those in the normal control group, respectively[(0.803 9±0.157 3) mV vs. (0.406 7±0.170 3) mV; (0.856 1±0.266 8)% vs. (0.650 0±0.197 6)%, P < 0.05]. Under static status, there were no significant differences in F-wave parameters of median nerve in the unaffected extremity of patients between BRSS Ⅰ-Ⅱ group and BRSS Ⅴ-Ⅵ group (P > 0.05). ②F-wave parameters of median nerve of unaffected extremity of patients in BRSS Ⅰ-Ⅱ group and BRSS Ⅴ-Ⅵ group under dynamic statewere higher than those under static status, without significant difference (P > 0.05), while the amplitude and appearance percentage of F wave of median nerve of unaffected extremity of patients in BRSS Ⅲ-Ⅳ group under dynamic statewere significantly higher than those under static state[(0.803 9±0.157 3) mV vs. (0.391 7±0.131 6) mV; (0.856 1±0.266 8 )% vs.(0.639 1 ±0.259 4)%,P < 0.05]. ③ There was no significant difference in F wave parameters among groups under static state(P > 0.05). However, under dynamic status, the amplitude and appearance percentage of F wave parameters of median nerve of unaffected extremity of patients in BRSS Ⅲ-Ⅳ group [(0.803 9±0.157 3) mV,(0.856 1±0.266 8)%] were significantly lower than those in the other two groups [(0.395 1±0.148 8),(0.437 1±0.157 6) mV;(0.612 5±0.232 8)%,(0.657 1±0.232 5)%,P < 0.05]. CONCLUSION: With the development of disease condition and the increase of muscular tension at anesthetic side, combination motor of affected extremity is caused following movement and muscular tension enhances to non-anesthetic-side. Therefore, F-wave parameters increase under dynamic status. 展开更多
关键词 WAVE Alternation in F-wave parameters of median nerve from unaffected extremity in stroke patients with hemiplegia under dynamic state
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Investigation of the Short-Time Photodissociation Dynamics of Furfural in S2 State by Resonance Raman and Quantum Chemistry Calculations
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作者 Kemei Pei Yueben Dong Lei Chen 《Computers, Materials & Continua》 SCIE EI 2018年第4期189-200,共12页
Raman(resonance Raman,FT-Raman),IR and UV-visible spectroscopy and quantum chemistry calculations were used to investigate the photodissociation dynamics of furfural in S2 state.The resonance Raman(RR)spectra indicate... Raman(resonance Raman,FT-Raman),IR and UV-visible spectroscopy and quantum chemistry calculations were used to investigate the photodissociation dynamics of furfural in S2 state.The resonance Raman(RR)spectra indicate that the photorelaxation dynamics for the S0→S2 excited state is predominantly along nine motions:C=O stretchν5(1667 cm-1),ring C=C antisymmetric stretchν6(1570 cm-1),ring C=C symmetric stretchν7(1472 cm-1),C2-O6-C5 symmetric stretch/C1-H8 rock in planeν8(1389 cm-1),C3-C4 stretch/C1-H8 rock in planeν9(1370 cm-1),C5-O6 stretch in planeν12(1154 cm-1),ring breathν13(1077 cm-1),C3-C4 stretchν14(1020 cm-1),C3-C2-O6 symmetric stretchν16(928 cm-1).Stable structures of S0,S1,S2,T1 and T2 states with Cs point group were optimized at CASSCF method in Franck-Condon region there are S2/S1 conical intersection was found by state average method and RR spectra. 展开更多
关键词 FURFURAL resonance Raman quantum chemistry calculation excited state structural dynamics
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Dynamics of Quantum State and Effective Hamiltonian with Vector Differential Form of Motion Method
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作者 Long Xiong Wei-Feng Zhuang Ming Gong 《Chinese Physics Letters》 SCIE EI CAS CSCD 2022年第7期36-40,共5页
Effective Hamiltonians in periodically driven systems have received widespread attention for realization of novel quantum phases, non-equilibrium phase transition, and Majorana mode. Recently, the study of effective H... Effective Hamiltonians in periodically driven systems have received widespread attention for realization of novel quantum phases, non-equilibrium phase transition, and Majorana mode. Recently, the study of effective Hamiltonian using various methods has gained great interest. We consider a vector differential equation of motion to derive the effective Hamiltonian for any periodically driven two-level system, and the dynamics of the spin vector are an evolution under the Bloch sphere. Here, we investigate the properties of this equation and show that a sudden change of the effective Hamiltonian is expected. Furthermore, we present several exact relations, whose expressions are independent of the different starting points. Moreover, we deduce the effective Hamiltonian from the high-frequency limit, which approximately equals the results in previous studies. Our results show that the vector differential equation of motion is not affected by a convergence problem, and thus, can be used to numerically investigate the effective models in any periodic modulating system. Finally, we anticipate that the proposed method can be applied to experimental platforms that require time-periodic modulation, such as ultracold atoms and optical lattices. 展开更多
关键词 Dynamics of Quantum State and Effective Hamiltonian with Vector Differential Form of Motion Method HAMILTONIAN VECTOR QUANTUM
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Clustering Algorithms to Analyze Molecular Dynamics Simulation Trajectories for Complex Chemical and Biological Systems
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作者 Jun-hui Peng Wei Wang +2 位作者 Ye-qing Yu Han-lin Gu Xuhui Huang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第4期404-420,613,共18页
Molecular dynamics (MD) simulation has become a powerful tool to investigate the structure- function relationship of proteins and other biological macromolecules at atomic resolution and biologically relevant timesc... Molecular dynamics (MD) simulation has become a powerful tool to investigate the structure- function relationship of proteins and other biological macromolecules at atomic resolution and biologically relevant timescales. MD simulations often produce massive datasets con- taining millions of snapshots describing proteins in motion. Therefore, clustering algorithms have been in high demand to be developed and applied to classify these MD snapshots and gain biological insights. There mainly exist two categories of clustering algorithms that aim to group protein conformations into clusters based on the similarity of their shape (geometric clustering) and kinetics (kinetic clustering). In this paper, we review a series of frequently used clustering algorithms applied in MD simulations, including divisive algorithms, ag- glomerative algorithms (single-linkage, complete-linkage, average-linkage, centroid-linkage and ward-linkage), center-based algorithms (K-Means, K-Medoids, K-Centers, and APM), density-based algorithms (neighbor-based, DBSCAN, density-peaks, and Robust-DB), and spectral-based algorithms (PCCA and PCCA+). In particular, differences between geomet- ric and kinetic clustering metrics will be discussed along with the performances of diflhrent clustering algorithms. We note that there does not exist a one-size-fits-all algorithm in the classification of MD datasets. For a specific application, the right choice of clustering algo- rithm should be based on the purpose of clustering, and the intrinsic properties of the MD conformational ensembles. Therefore, a main focus of our review is to describe the merits and limitations of each clustering algorithm. We expect that this review would be helpful to guide researchers to choose appropriate clustering algorithms for their own MD datasets. 展开更多
关键词 Molecular dynamics simulation Clustering algorithms Markov state models Protein dynamics
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BTT autopilot design for agile missiles with aerodynamic uncertainty
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作者 Yueyue Ma Jie Guo Shengjing Tang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第4期802-812,共11页
The approach to the synthesis of autopilot with aerody- namic uncertainty is investigated in order to achieve large maneu- verability of agile missiles. The dynamics of the agile missile with reaction-jet control syst... The approach to the synthesis of autopilot with aerody- namic uncertainty is investigated in order to achieve large maneu- verability of agile missiles. The dynamics of the agile missile with reaction-jet control system (RCS) are presented. Subsequently, the cascade control scheme based on the bank-to-turn (B-I-T) steering technique is described. To address the aerodynamic un- certainties encountered by the control system, the active distur- bance rejection control (ADRC) method is introduced in the autopi- lot design. Furthermore, a compound controller, using extended state observer (ESO) to online estimate system uncertainties and calculate derivative of command signals, is designed based on dynamic surface control (DSC). Nonlinear simulation results show the feasibility of the proposed approach and validate the robust- ness of the controller with severe unmodeled dynamics. 展开更多
关键词 agile missile AUTOPILOT high angle of attack active dis-turbance rejection control (ADRC) dynamic surface control (DSC) extended state observer (ESO).
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Analysis of Higher Order System with Impulse Exciting Functions in Z-Domain
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作者 Branislav Dobrucký Pavol Štefanec +2 位作者 Mariana Beňová Oleg V. Chernoyarov Michal Pokorný 《Circuits and Systems》 2016年第11期3951-3970,共20页
This paper deals with mathematical modelling of impulse waveforms and impulse switching functions used in electrical engineering. Impulse switching functions are later investigated using direct and inverse z-transform... This paper deals with mathematical modelling of impulse waveforms and impulse switching functions used in electrical engineering. Impulse switching functions are later investigated using direct and inverse z-transformation. The results make possible to present those functions as infinite series expressed in pure numerical, exponential or trigonometric forms. The main advantage of used approach is the possibility to calculate investigated variables directly in any instant of time;dynamic state can be solved with the step of sequences (T/6, T/12) that means very fast. Theoretically derived waveforms are compared with simulation worked-out results as well as results of circuit emulator LT spice which are given in the paper. 展开更多
关键词 Impulse Systems Switching Function Z-Transformation Inverse Z-Transformation Steady State Operation dynamical State Model Modelling and Simulation
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