One of the most effective methods for sand control is the chemical consolidation of sandstone structures.In this paper,the impacts of crude oil and brine in the static state and the impact of the flow rates of the flu...One of the most effective methods for sand control is the chemical consolidation of sandstone structures.In this paper,the impacts of crude oil and brine in the static state and the impact of the flow rates of the fluids in the dynamic state have been assessed at the reservoir conditions.The analyses in this research were Young’s modulus,compressive strength,porosity,and permeability which were done on core samples after and before fluid contact.Samples made with two different resins showed good resistance to crude oil in both states.No considerable change was seen in the analyses even at high crude oil injection rates in the dynamic state.Conversely,brine caused a noticeable change in the analyses in both states.In the presence of brine at the static state,Young’s modulus and compressive strength respectively decreased by 37.5%and 34.5%for epoxy cores,whereas these parameters respectively reduced by 30%and 41%for furan cores.In brine presence at the dynamic state,compressive strength reduction was 10.28 MPa for furan and 6.28 MPa for epoxy samples and their compressive strength reached 16.75 MPa and 26.54 MPa respectively which are higher than the critical point to be known as weak sandstone core.Moreover,Young’s modulus decrease values for furan and epoxy samples were respectively 0.37 GPa and 0.44 GPa.Therefore,brine had a more destructive effect on the mechanical characteristics of samples in the static state than the dynamic one for two resins.In addition,brine injection increased permeability by about 13.6%for furan and 34.8%for epoxy.Also,porosity raised by about 21.8%for furan,and 19%for epoxy by brine injection.The results showed that the chemical sand consolidation weakens in the face of brine production along with crude oil which can lead to increasing cost of oil production and treating wellbore again.展开更多
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
The development of low-carbon energy systems and renewable energy sources(RESs)are critical to solving the energy crisis around the world.However,renewable energy gen eration control strategies lead to fault character...The development of low-carbon energy systems and renewable energy sources(RESs)are critical to solving the energy crisis around the world.However,renewable energy gen eration control strategies lead to fault characteristics such as fault current amplitude limitation and phase angle distortion.Focusing on large-scale renewable energy transmission lines,the sensitivity of traditional current differential protection and distance protection may be reduced,and there is even the risk of maloperation.Therefore,a suitable transmission line model is established,which considers the distributed capacitance.Af terward,a novel dynamic state estimation based protection(DSEBP)for large-scale renewable energy transmission lines is proposed.The proposed DSEBP adopts instantaneous measure ments and additional protection criteria to ensure the quick ac tion and reliability.Finally,faults are identified by checking the matching degree between the actual measurements and the es tablished transmission line model.The performance of the pro posed DSEBP is verified through PSCAD/EMTDC and realtime digital simulator(RTDS)hardware-in-loop tests.The re sults demonstrate that the proposed DSEBP can identify vari ous types of faults quickly and reliably.Meanwhile,the pro posed DSEBP has a better capability to withstand fault resis tance and disturbance.展开更多
Accurate generator information is crucial for the efficient control and operation of a power system.This study proposes a hierarchical data-driven approach for dynamic state estimation(DSE)of generators using cellular...Accurate generator information is crucial for the efficient control and operation of a power system.This study proposes a hierarchical data-driven approach for dynamic state estimation(DSE)of generators using cellular computational networks(CCNs)structure.The proposed method initially divides the problem of dynamic state estimation into multiple layers through hierarchical architecture.In the prediction layer,CCNs are employed to reduce the system scale by considering only relevant generators.In the correction layer,a novel adaptive filter is utilized to increase data abundance.Simulation results demonstrate that the proposed hierarchical data-driven method can accurately estimate states using PMU data alone while maintaining high computational efficiency.Additionally,it offers easy scalability and strong robustness against uncertainties.The proposed method has potential applications in online dynamic state estimation and real-time security monitoring.展开更多
With the application of communication network technology in power systems,traditional power grids have gradually developed into cyber-physical systems(CPS),and false data injection(FDI)attacks have become a hidden dan...With the application of communication network technology in power systems,traditional power grids have gradually developed into cyber-physical systems(CPS),and false data injection(FDI)attacks have become a hidden danger that affects the operation of power CPS.To solve the problems of low estimation accuracy and model uncertainty when the extended Kalman filter(EKF)algorithm is subjected to FDI attacks in power systems,an interpolation adaptive H_(∞)extended Kalman filter(IAHEKF)algorithm is proposed for the dynamic state estimation of power systems under FDI attacks.The new algorithm uses an interpolation strategy to reduce the linearization error of the EKF algorithm and introduces adaptive H_(∞)theory to update the error covariance,minimizing the error upper bound caused by model uncertainty;moreover,it uses the Sage-Husa estimator to calculate the noise covariance,reducing the impact of unknown noise on state estimation.Finally,tests are conducted on the IEEE-14 node system and IEEE-30 node system,and the results show that the IAHEKF algorithm has higher estimation accuracy under different attack scenarios.展开更多
In recent years, integrated electricity-gas systems(IEGSs) have attracted widespread attention. The unifiedscheduling and control of the IEGS depends on high-precisionoperating data. To this end, it is necessary to es...In recent years, integrated electricity-gas systems(IEGSs) have attracted widespread attention. The unifiedscheduling and control of the IEGS depends on high-precisionoperating data. To this end, it is necessary to establish anappropriate state estimation (SE) model for IEGS to filter theraw measured data. Considering that power systems and naturalgas systems have different time scales and sampling periods, thispaper proposes a dynamic state estimation (DSE) method basedon a Kalman filter that can consider the dynamic characteristicsof natural gas pipelines. First, the standardized state transitionequations for the gas system are developed by applying the finitedifference method to the partial differential equations (PDEs) ofthe gas system;then the DSE model for IEGS is formulatedbased on a Kalman filter;also, the measurements from theelectricity system and the gas system with different samplingperiods are fused to ensure the observability of DSE by using theinterpolation method. The IEEE 39-bus electricity system and the18-nodes Belgium gas system are integrated as the test systems.Simulation results verify the proposed method’s accuracy andcalculation efficiency.展开更多
In this paper,a robust adaptive unscented Kalman filter(RAUKF)is developed to mitigate the unfavorable effects derived from uncertainties in noise and in the model.To address these issues,a robust M-estimator is first...In this paper,a robust adaptive unscented Kalman filter(RAUKF)is developed to mitigate the unfavorable effects derived from uncertainties in noise and in the model.To address these issues,a robust M-estimator is first utilized to update the measurement noise covariance.Next,to deal with the effects of model parameter errors while considering the computational complexity and real-time requirements of dynamic state estimation,an adaptive update method is produced.The proposed method is integrated with spherical simplex unscented transformation technology,and then a novel derivative-free filter is proposed to dynamically track the states of the power system against uncertainties.Finally,the effectiveness and robustness of the proposed method are demonstrated through extensive simulation experiments on an IEEE 39-bus test system.Compared with other methods,the proposed method can capture the dynamic characteristics of a synchronous generator more reliably.展开更多
The dynamic characteristic evaluation is an important prerequisite for safe and reliable operation of the mediumvoltage DC integrated power system(MIPS),and the dynamic state estimation is an essential technical appro...The dynamic characteristic evaluation is an important prerequisite for safe and reliable operation of the mediumvoltage DC integrated power system(MIPS),and the dynamic state estimation is an essential technical approach to the evaluation.Unlike the electromechanical transient process in a traditional power system,periodic change in pulse load of the MIPS is an electromagnetic transient process.As the system state suddenly changes in the range of a smaller time constant,it is difficult to estimate the dynamic state due to periodic disturbance.This paper presents a dynamic mathematical model of the MIPS according to the network structure and control strategy,thereby overcoming the restrictions of algebraic variables on the estimation and developing a dynamic state estimation method based on the extended Kalman filter.Using the method of adding fictitious process noise,it is possible to solve the problem that the linearized algorithm of the MIPS model is less reliable when an abrupt change occurs in the pulse load.Therefore,the accuracy of the dynamic state estimation and the stability of the filter can be improved under the periodic disturbance of pulse load.The simulation and experimental results confirm that the proposed model and method are feasible and effective.展开更多
High penetration of Converter Interfaced Generations(CIGs)presents challenges in both microgrid(μGrid)circuit and other system with CIG resources,such as wind farms and PV plants.Specifically,protection challenges ar...High penetration of Converter Interfaced Generations(CIGs)presents challenges in both microgrid(μGrid)circuit and other system with CIG resources,such as wind farms and PV plants.Specifically,protection challenges are mainly brought by the insufficient separation between fault and load currents,especially forμGrids in islanded operation,and the short connection length inμGrids.In addition,CIG resources exhibit limited inertia and weak coupling to any rotating machinery,which can result in large transients during disturbances.To address the above challenges,this paper proposes a Dynamic State Estimation(DSE)based algorithm for protection and control of systems with substantial CIG resources such as aμGrid.It requires a high-fidelity dynamic model and time domain(sampled value)measurements.ForμGrid circuit protection,the algorithm dependably and securely detects internal faults by checking the consistency between the circuit model and available measurements.For CIG control,the algorithm estimates the frequency at other parts of aμGrid using CIG local information only and then utilizes it to provide supplementary feedback control.Simulation results prove that DSE based protection algorithm detects internal faults faster,ignores external faults and has improved sensitivity towards high impedance faults when compared to conventional protection methods.DSE based CIG control scheme also minimizes output oscillation and transient during system disturbances.展开更多
In this paper,we present a time-domain dynamic state estimation for unbalanced three-phase power systems.The dynamic nature of the estimator stems from an explicit consideration of the electromagnetic dynamics of the ...In this paper,we present a time-domain dynamic state estimation for unbalanced three-phase power systems.The dynamic nature of the estimator stems from an explicit consideration of the electromagnetic dynamics of the network,i.e.,the dynamics of the electrical lines.This enables our approach to release the assumption of the network being in quasi-steady state.Initially,based on the line dynamics,we derive a graphbased dynamic system model.To handle the large number of interacting variables,we propose a port-Hamiltonian modeling approach.Based on the port-Hamiltonian model,we then follow an observer-based approach to develop a dynamic estimator.The estimator uses synchronized sampled value measurements to calculate asymptotic convergent estimates for the unknown bus voltages and currents.The design and implementation of the estimator are illustrated through the IEEE 33-bus system.Numerical simulations verify the estimator to produce asymptotic exact estimates,which are able to detect harmonic distortion and sub-second transients as arising from converterbased resources.展开更多
We propose a new and efficient algorithm to detect, identify, and correct measurement errors and branch parameter errors of power systems. A dynamic state estimation algorithm is used based on the Kalman filter theory...We propose a new and efficient algorithm to detect, identify, and correct measurement errors and branch parameter errors of power systems. A dynamic state estimation algorithm is used based on the Kalman filter theory. The proposed algorithm also successfully detects and identifies sudden load changes in power systems. The method uses three normalized vectors to process errors at each sampling time: normalized measurement residual, normalized Lagrange multiplier, and normalized innovation vector. An IEEE 14-bus test system was used to verify and demonstrate the effectiveness of the proposed method. Numerical results are presented and discussed to show the accuracy of the method.展开更多
This paper develops an adaptive two-stage unscented Kalman filter(ATSUKF)to accurately track operation states of the synchronous generator(SG)under cyber attacks.To achieve high fidelity,considering the excitation sys...This paper develops an adaptive two-stage unscented Kalman filter(ATSUKF)to accurately track operation states of the synchronous generator(SG)under cyber attacks.To achieve high fidelity,considering the excitation system of SGs,a detailed 9~(th)-order SG model for dynamic state estimation is established.Then,for several common cyber attacks against measurements,a two-stage unscented Kalman filter is proposed to estimate the model state and the bias in parallel.Subsequently,to solve the deterioration problem of state estimation performance caused by the mismatch between noise statistical characteristics and model assumptions,a multi-dimensional adaptive factor matrix is derived to modify the noise covariance matrix.Finally,a large number of simulation experiments are carried out on the IEEE 39-bus system,which shows that the proposed filter can accurately track the SG state under different abnormal test conditions.展开更多
Dynamic state estimation(DSE)accurately tracks the dynamics of power systems and demonstrates the evolution of the system state in real time.This paper proposes a DSE approach for a doubly-fed induction generator(DFIG...Dynamic state estimation(DSE)accurately tracks the dynamics of power systems and demonstrates the evolution of the system state in real time.This paper proposes a DSE approach for a doubly-fed induction generator(DFIG)with unknown inputs based on adaptive interpolation and cubature Kalman filter(AICKF-UI).DFIGs adopt different control strategies in normal and fault conditions;thus,the existing DSE approaches based on the conventional control model of DFIG are not applicable in all cases.Consequently,the DSE model of DFIGs is reformulated to consider the converter controller outputs as unknown inputs,which are estimated together with the DFIG dynamic states by an exponential smoothing model and augmented-state cubature Kalman filter.Furthermore,as the reporting rate of existing synchro-phasor data is not sufficiently high to capture the fast dynamics of DFIGs,a large estimation error may occur or the DSE approach may diverge.To this end,in this paper,a local-truncation-error-guided adaptive interpolation approach is developed.Extensive simulations conducted on a wind farm and the modified IEEE 39-bus test system show that the proposed AICKF-UI can(1)effectively address the divergence issues of existing cubature Kalman filters while being computationally more efficient;(2)accurately track the dynamic states and unknown inputs of the DFIG;and(3)deal with various types of system operating conditions such as time-varying wind and different system faults.展开更多
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
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
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
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
Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a si...Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a simulation-based TDGS model is established,and a surrogate-based model,grid search algorithm-particle swarm optimization-genetic algorithm-multi-output least squares support vector regression,is established.Among them,hyperparameter optimization algorithm’s effectiveness is confirmed through test functions.Subsequently,an adaptive surrogate-based probability density evolution method(PDEM)considering random track geometry irregularity(TGI)is developed.Finally,taking curved train-steel spring floating slab track-U beam as case study,the surrogate-based model trained on simulation datasets not only shows accuracy in both time and frequency domains,but also surpasses existing models.Additionally,the adaptive surrogate-based PDEM shows high accuracy and efficiency,outperforming Monte Carlo simulation and simulation-based PDEM.The reliability assessment shows that the TDGS part peak management indexes,left/right vertical dynamic irregularity,right alignment dynamic irregularity,and track twist,have reliability values of 0.9648,0.9918,0.9978,and 0.9901,respectively.The TDGS mean management index,i.e.,track quality index,has reliability value of 0.9950.These findings show that the proposed framework can accurately and efficiently assess the reliability of curved low-stiffness track-viaducts,providing a theoretical basis for the TGI maintenance.展开更多
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
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
文摘One of the most effective methods for sand control is the chemical consolidation of sandstone structures.In this paper,the impacts of crude oil and brine in the static state and the impact of the flow rates of the fluids in the dynamic state have been assessed at the reservoir conditions.The analyses in this research were Young’s modulus,compressive strength,porosity,and permeability which were done on core samples after and before fluid contact.Samples made with two different resins showed good resistance to crude oil in both states.No considerable change was seen in the analyses even at high crude oil injection rates in the dynamic state.Conversely,brine caused a noticeable change in the analyses in both states.In the presence of brine at the static state,Young’s modulus and compressive strength respectively decreased by 37.5%and 34.5%for epoxy cores,whereas these parameters respectively reduced by 30%and 41%for furan cores.In brine presence at the dynamic state,compressive strength reduction was 10.28 MPa for furan and 6.28 MPa for epoxy samples and their compressive strength reached 16.75 MPa and 26.54 MPa respectively which are higher than the critical point to be known as weak sandstone core.Moreover,Young’s modulus decrease values for furan and epoxy samples were respectively 0.37 GPa and 0.44 GPa.Therefore,brine had a more destructive effect on the mechanical characteristics of samples in the static state than the dynamic one for two resins.In addition,brine injection increased permeability by about 13.6%for furan and 34.8%for epoxy.Also,porosity raised by about 21.8%for furan,and 19%for epoxy by brine injection.The results showed that the chemical sand consolidation weakens in the face of brine production along with crude oil which can lead to increasing cost of oil production and treating wellbore again.
文摘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.
基金supported by National Natural Science Foundation of ChinaState Grid Corporation Joint Fund for Smart Grid(No.U2066210).
文摘The development of low-carbon energy systems and renewable energy sources(RESs)are critical to solving the energy crisis around the world.However,renewable energy gen eration control strategies lead to fault characteristics such as fault current amplitude limitation and phase angle distortion.Focusing on large-scale renewable energy transmission lines,the sensitivity of traditional current differential protection and distance protection may be reduced,and there is even the risk of maloperation.Therefore,a suitable transmission line model is established,which considers the distributed capacitance.Af terward,a novel dynamic state estimation based protection(DSEBP)for large-scale renewable energy transmission lines is proposed.The proposed DSEBP adopts instantaneous measure ments and additional protection criteria to ensure the quick ac tion and reliability.Finally,faults are identified by checking the matching degree between the actual measurements and the es tablished transmission line model.The performance of the pro posed DSEBP is verified through PSCAD/EMTDC and realtime digital simulator(RTDS)hardware-in-loop tests.The re sults demonstrate that the proposed DSEBP can identify vari ous types of faults quickly and reliably.Meanwhile,the pro posed DSEBP has a better capability to withstand fault resis tance and disturbance.
基金supported in part by the National Natural Science Foundation of China(No.62203395)in part by the China Postdoctoral Science Foundation(No.2023TQ0306)+1 种基金in part by the Natural Science Foundation of Henan Province(No.242300421167)in part by the Postdoctoral Research Project of Henan Province(No.202101011).
文摘Accurate generator information is crucial for the efficient control and operation of a power system.This study proposes a hierarchical data-driven approach for dynamic state estimation(DSE)of generators using cellular computational networks(CCNs)structure.The proposed method initially divides the problem of dynamic state estimation into multiple layers through hierarchical architecture.In the prediction layer,CCNs are employed to reduce the system scale by considering only relevant generators.In the correction layer,a novel adaptive filter is utilized to increase data abundance.Simulation results demonstrate that the proposed hierarchical data-driven method can accurately estimate states using PMU data alone while maintaining high computational efficiency.Additionally,it offers easy scalability and strong robustness against uncertainties.The proposed method has potential applications in online dynamic state estimation and real-time security monitoring.
基金Supported by the National Key Research and Development Plan Project of China(2021YFB2601304)Shaanxi Provincial Key Research and Development Plan Project(2022GY-193)the Innovation Capability Support Program of Shaanxi(2021TD-28,2022KXJ-144).
文摘With the application of communication network technology in power systems,traditional power grids have gradually developed into cyber-physical systems(CPS),and false data injection(FDI)attacks have become a hidden danger that affects the operation of power CPS.To solve the problems of low estimation accuracy and model uncertainty when the extended Kalman filter(EKF)algorithm is subjected to FDI attacks in power systems,an interpolation adaptive H_(∞)extended Kalman filter(IAHEKF)algorithm is proposed for the dynamic state estimation of power systems under FDI attacks.The new algorithm uses an interpolation strategy to reduce the linearization error of the EKF algorithm and introduces adaptive H_(∞)theory to update the error covariance,minimizing the error upper bound caused by model uncertainty;moreover,it uses the Sage-Husa estimator to calculate the noise covariance,reducing the impact of unknown noise on state estimation.Finally,tests are conducted on the IEEE-14 node system and IEEE-30 node system,and the results show that the IAHEKF algorithm has higher estimation accuracy under different attack scenarios.
基金This work was supported in part by National Natural Science Foundation of China(51777067)and(52077076)in part by funding from the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(LAPS2021-18).
文摘In recent years, integrated electricity-gas systems(IEGSs) have attracted widespread attention. The unifiedscheduling and control of the IEGS depends on high-precisionoperating data. To this end, it is necessary to establish anappropriate state estimation (SE) model for IEGS to filter theraw measured data. Considering that power systems and naturalgas systems have different time scales and sampling periods, thispaper proposes a dynamic state estimation (DSE) method basedon a Kalman filter that can consider the dynamic characteristicsof natural gas pipelines. First, the standardized state transitionequations for the gas system are developed by applying the finitedifference method to the partial differential equations (PDEs) ofthe gas system;then the DSE model for IEGS is formulatedbased on a Kalman filter;also, the measurements from theelectricity system and the gas system with different samplingperiods are fused to ensure the observability of DSE by using theinterpolation method. The IEEE 39-bus electricity system and the18-nodes Belgium gas system are integrated as the test systems.Simulation results verify the proposed method’s accuracy andcalculation efficiency.
基金supported by the National Natural Science Foundation of China(No.62073121)the National Natural Science Foundation of China-State Grid Joint Fund for Smart Grid(No.U1966202)the Six Talent Peaks High Level Project of Jiangsu Province(No.2017-XNY-004)。
文摘In this paper,a robust adaptive unscented Kalman filter(RAUKF)is developed to mitigate the unfavorable effects derived from uncertainties in noise and in the model.To address these issues,a robust M-estimator is first utilized to update the measurement noise covariance.Next,to deal with the effects of model parameter errors while considering the computational complexity and real-time requirements of dynamic state estimation,an adaptive update method is produced.The proposed method is integrated with spherical simplex unscented transformation technology,and then a novel derivative-free filter is proposed to dynamically track the states of the power system against uncertainties.Finally,the effectiveness and robustness of the proposed method are demonstrated through extensive simulation experiments on an IEEE 39-bus test system.Compared with other methods,the proposed method can capture the dynamic characteristics of a synchronous generator more reliably.
基金supported by the National Key Basic Research Program of China(973 Program)(No.613294)the Natural Science Foundation of China(No.51877211)
文摘The dynamic characteristic evaluation is an important prerequisite for safe and reliable operation of the mediumvoltage DC integrated power system(MIPS),and the dynamic state estimation is an essential technical approach to the evaluation.Unlike the electromechanical transient process in a traditional power system,periodic change in pulse load of the MIPS is an electromagnetic transient process.As the system state suddenly changes in the range of a smaller time constant,it is difficult to estimate the dynamic state due to periodic disturbance.This paper presents a dynamic mathematical model of the MIPS according to the network structure and control strategy,thereby overcoming the restrictions of algebraic variables on the estimation and developing a dynamic state estimation method based on the extended Kalman filter.Using the method of adding fictitious process noise,it is possible to solve the problem that the linearized algorithm of the MIPS model is less reliable when an abrupt change occurs in the pulse load.Therefore,the accuracy of the dynamic state estimation and the stability of the filter can be improved under the periodic disturbance of pulse load.The simulation and experimental results confirm that the proposed model and method are feasible and effective.
基金This work is supported by Electric Power Research Institute(EPRI).Its support is greatly appreciated.
文摘High penetration of Converter Interfaced Generations(CIGs)presents challenges in both microgrid(μGrid)circuit and other system with CIG resources,such as wind farms and PV plants.Specifically,protection challenges are mainly brought by the insufficient separation between fault and load currents,especially forμGrids in islanded operation,and the short connection length inμGrids.In addition,CIG resources exhibit limited inertia and weak coupling to any rotating machinery,which can result in large transients during disturbances.To address the above challenges,this paper proposes a Dynamic State Estimation(DSE)based algorithm for protection and control of systems with substantial CIG resources such as aμGrid.It requires a high-fidelity dynamic model and time domain(sampled value)measurements.ForμGrid circuit protection,the algorithm dependably and securely detects internal faults by checking the consistency between the circuit model and available measurements.For CIG control,the algorithm estimates the frequency at other parts of aμGrid using CIG local information only and then utilizes it to provide supplementary feedback control.Simulation results prove that DSE based protection algorithm detects internal faults faster,ignores external faults and has improved sensitivity towards high impedance faults when compared to conventional protection methods.DSE based CIG control scheme also minimizes output oscillation and transient during system disturbances.
文摘In this paper,we present a time-domain dynamic state estimation for unbalanced three-phase power systems.The dynamic nature of the estimator stems from an explicit consideration of the electromagnetic dynamics of the network,i.e.,the dynamics of the electrical lines.This enables our approach to release the assumption of the network being in quasi-steady state.Initially,based on the line dynamics,we derive a graphbased dynamic system model.To handle the large number of interacting variables,we propose a port-Hamiltonian modeling approach.Based on the port-Hamiltonian model,we then follow an observer-based approach to develop a dynamic estimator.The estimator uses synchronized sampled value measurements to calculate asymptotic convergent estimates for the unknown bus voltages and currents.The design and implementation of the estimator are illustrated through the IEEE 33-bus system.Numerical simulations verify the estimator to produce asymptotic exact estimates,which are able to detect harmonic distortion and sub-second transients as arising from converterbased resources.
文摘We propose a new and efficient algorithm to detect, identify, and correct measurement errors and branch parameter errors of power systems. A dynamic state estimation algorithm is used based on the Kalman filter theory. The proposed algorithm also successfully detects and identifies sudden load changes in power systems. The method uses three normalized vectors to process errors at each sampling time: normalized measurement residual, normalized Lagrange multiplier, and normalized innovation vector. An IEEE 14-bus test system was used to verify and demonstrate the effectiveness of the proposed method. Numerical results are presented and discussed to show the accuracy of the method.
基金supported by the National Natural Science Foundation of China(No.62073121)the National Natural Science Foundation of China-State Grid Joint Fund for Smart Grid(No.U1966202)+1 种基金the Six Talent Peaks High Level Project of Jiangsu Province(No.2017-XNY-004)the Natural Sciences and Engineering Research Council(NSERC)of Canada。
文摘This paper develops an adaptive two-stage unscented Kalman filter(ATSUKF)to accurately track operation states of the synchronous generator(SG)under cyber attacks.To achieve high fidelity,considering the excitation system of SGs,a detailed 9~(th)-order SG model for dynamic state estimation is established.Then,for several common cyber attacks against measurements,a two-stage unscented Kalman filter is proposed to estimate the model state and the bias in parallel.Subsequently,to solve the deterioration problem of state estimation performance caused by the mismatch between noise statistical characteristics and model assumptions,a multi-dimensional adaptive factor matrix is derived to modify the noise covariance matrix.Finally,a large number of simulation experiments are carried out on the IEEE 39-bus system,which shows that the proposed filter can accurately track the SG state under different abnormal test conditions.
基金supported by the National Natural Science Foundation of China(No.51725702)。
文摘Dynamic state estimation(DSE)accurately tracks the dynamics of power systems and demonstrates the evolution of the system state in real time.This paper proposes a DSE approach for a doubly-fed induction generator(DFIG)with unknown inputs based on adaptive interpolation and cubature Kalman filter(AICKF-UI).DFIGs adopt different control strategies in normal and fault conditions;thus,the existing DSE approaches based on the conventional control model of DFIG are not applicable in all cases.Consequently,the DSE model of DFIGs is reformulated to consider the converter controller outputs as unknown inputs,which are estimated together with the DFIG dynamic states by an exponential smoothing model and augmented-state cubature Kalman filter.Furthermore,as the reporting rate of existing synchro-phasor data is not sufficiently high to capture the fast dynamics of DFIGs,a large estimation error may occur or the DSE approach may diverge.To this end,in this paper,a local-truncation-error-guided adaptive interpolation approach is developed.Extensive simulations conducted on a wind farm and the modified IEEE 39-bus test system show that the proposed AICKF-UI can(1)effectively address the divergence issues of existing cubature Kalman filters while being computationally more efficient;(2)accurately track the dynamic states and unknown inputs of the DFIG;and(3)deal with various types of system operating conditions such as time-varying wind and different system faults.
基金the National Nature Science Foundation of China(No.11674101,No.21873030 and No.91850202)。
文摘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.
基金Supported by the National Natural Science Foundation of China under Grant Nos 21303255,21273274 and 91121006
文摘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.
基金This work was supported in parts by National Natural Science Foundation of China(No.21673208)Zhejiang Provincial Natural Science Foundation of China(No.LY16B070009).
文摘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.
基金supported by the National Natural Science Foundation of China (Grant No. 11774328)。
文摘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.
基金Project(52072412)supported by the National Natural Science Foundation of China。
文摘Traditional track dynamic geometric state(TDGS)simulation incurs substantial computational burdens,posing challenges for developing reliability assessment approach that accounts for TDGS.To overcome these,firstly,a simulation-based TDGS model is established,and a surrogate-based model,grid search algorithm-particle swarm optimization-genetic algorithm-multi-output least squares support vector regression,is established.Among them,hyperparameter optimization algorithm’s effectiveness is confirmed through test functions.Subsequently,an adaptive surrogate-based probability density evolution method(PDEM)considering random track geometry irregularity(TGI)is developed.Finally,taking curved train-steel spring floating slab track-U beam as case study,the surrogate-based model trained on simulation datasets not only shows accuracy in both time and frequency domains,but also surpasses existing models.Additionally,the adaptive surrogate-based PDEM shows high accuracy and efficiency,outperforming Monte Carlo simulation and simulation-based PDEM.The reliability assessment shows that the TDGS part peak management indexes,left/right vertical dynamic irregularity,right alignment dynamic irregularity,and track twist,have reliability values of 0.9648,0.9918,0.9978,and 0.9901,respectively.The TDGS mean management index,i.e.,track quality index,has reliability value of 0.9950.These findings show that the proposed framework can accurately and efficiently assess the reliability of curved low-stiffness track-viaducts,providing a theoretical basis for the TGI maintenance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10875076,11305098 and 11147020the Fundamental Research Funds for the Central Universities under Grant No GK201302008the Interdisciplinary Incubation Project of Shaanxi Normal University under Grant No 5
文摘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.
基金This work was supported by the National Natural Science Foundation of China （No.21033002 and No.20803066） and the National Basic Research Program of China （No.2007CB815203）.
文摘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.
