Multi-scale Incremental Analysis Update Scheme and Its Application to Typhoon Mangkhut(2018)Prediction

In the traditional incremental analysis update(IAU)process,all analysis increments are treated as constant forcing in a model’s prognostic equations over a certain time window.This approach effectively reduces high-frequency oscillations introduced by data assimilation.However,as different scales of increments have unique evolutionary speeds and life histories in a numerical model,the traditional IAU scheme cannot fully meet the requirements of short-term forecasting for the damping of high-frequency noise and may even cause systematic drifts.Therefore,a multi-scale IAU scheme is proposed in this paper.Analysis increments were divided into different scale parts using a spatial filtering technique.For each scale increment,the optimal relaxation time in the IAU scheme was determined by the skill of the forecasting results.Finally,different scales of analysis increments were added to the model integration during their optimal relaxation time.The multi-scale IAU scheme can effectively reduce the noise and further improve the balance between large-scale and small-scale increments in the model initialization stage.To evaluate its performance,several numerical experiments were conducted to simulate the path and intensity of Typhoon Mangkhut(2018)and showed that:(1)the multi-scale IAU scheme had an obvious effect on noise control at the initial stage of data assimilation;(2)the optimal relaxation time for large-scale and small-scale increments was estimated as 6 h and 3 h,respectively;(3)the forecast performance of the multi-scale IAU scheme in the prediction of Typhoon Mangkhut(2018)was better than that of the traditional IAU scheme.The results demonstrate the superiority of the multi-scale IAU scheme.

Use of Incremental Analysis Updates in 4D-Var Data Assimilation

The four-dimensional variational （4D-Var） data assimilation systems used in most operational and research centers use initial condition increments as control variables and adjust initial increments to find optimal analysis solutions. This approach may sometimes create discontinuities in analysis fields and produce undesirable spin ups and spin downs. This study explores using incremental analysis updates （IAU） in 4D-Var to reduce the analysis discontinuities. IAU-based 4D-Var has almost the same mathematical formula as conventional 4D-Var if the initial condition increments are replaced with time-integrated increments as control variables. The IAU technique was implemented in the NASA/GSFC 4D-Var prototype and compared against a control run without IAU. The results showed that the initial precipitation spikes were removed and that other discontinuities were also reduced, especially for the analysis of surface temperature.

Application of a Typhoon Initialization Scheme Based on the Incremental Analysis Updates Technique in a Rapid Update Cycle System

Initialization of tropical cyclones plays an important role in typhoon numerical prediction. This study applied a typhoon initialization scheme based on the incremental analysis updates (IAU) technique in a rapid refresh system to improve the prediction of Typhoon Lekima (2019). Two numerical sensitivity experiments with or without application of the IAU technique after performing vortex relocation and wind adjustment procedures were conducted for comparison with the control experiment, which did not involve a typhoon initialization scheme. Analysis of the initial fields indicated that the relocation procedure shifted the typhoon circulation to the observed typhoon region, and the wind speeds became closer to the observations following the wind adjustment procedure. Comparison of the results of the sensitivity and control experiments revealed that the vortex relocation and wind adjustment procedures could improve the prediction of typhoon track and intensity in the first 6-h period, and that these improvements were extended throughout the first 12-h period of the prediction by the IAU technique. The new typhoon initialization scheme also improved the simulated typhoon structure in terms of not only the wind speed and warm core prediction but also the organization of the eye of Typhoon Lekima. Diagnosis of the tendencies of variables showed that use of the IAU technique in a typhoon initialization scheme is efficacious in resolving the spurious high-frequency noise problem such that the model is able to reach equilibrium as soon as possible.

INCREMENTAL ANALYSIS FOR NONLINEAR RUBBER-LIKE MATERIALS BY HYBRID STRESS FINITE ELEMENT

In this paper, on the basis of the incremental Reissner variational principle.a nonlinear finite element analysis has been accomplished and a formulation of hybrid stress element has been presented for incompressible Mooney rubber-like materials. The corrected terms of the non-equilibrium force and the incompressibility deviation are considered in the formulation. The computed values of numerical example agree very closely with the exact solution.

Implementation of the Incremental Analysis Update Initialization Scheme in the Tropical Regional Atmospheric Modeling System under the Replay Configuration

In traditional simulations of heavy rainfall events, the regional model is often initialized by using a global reanalysis dataset and a cold start method. An alternative to using global analysis data is to gradually introduce the analysis field via an incremental analysis update(IAU) method under the replay configuration. We found substantial differences in the forecast of a heavy rainfall event in southern China between a precipitation forecast using the traditional method and a forecast using the IAU method in the Tropical Regional Atmospheric Modeling System(TRAMS),based on the ECMWF global analysis. The IAU method is efficient in removing spurious high-frequency gravity wave noise, especially when the relaxation time is more than 90 min. The regional model needs to be pre-integrated for about 12 h to warm up the convective system in the background field. The improvement by the IAU method is supported by verification of simulations over 1 month(1–30 April 2019). In general, the IAU technique improves the initialization and spin-up process in the simulation of the heavy rainfall event.

Incremental dynamic analysis of concrete gravity dams including base and lift joints

The growth in computer processing power has made it possible to use time-consuming analysis methods such as incremental dynamic analysis（IDA） with higher accuracy in less time.In an IDA study,a series of earthquake records are applied to a structure at successively increasing intensity levels,which causes the structure to shift from the elastic state into the inelastic state and finally into collapse.In this way,the limit-states and capacity of a structure can be determined.In the present research,the IDA of a concrete gravity dam considering a nonlinear concrete behavior,and sliding planes within the dam body and at the dam-foundation interface,is performed.The influence of the friction angle and lift joint slope on the response parameters are investigated and the various limit-states of the dam are recognized.It is observed that by introducing a lift joint,the tensile damage can be avoided for the dam structure.The lift joint sliding is essentially independent of the base joint friction angle and the upper ligament over the inclined lift joint slides into the upstream direction in strong earthquakes.

Equating incremental dynamic analysis with static nonlinear analysis at near-field excitation

In an incremental dynamic analysis(IDA) using a set of ground motion records,nonlinear time history analysis needs to be performed on structures.It is well recognized that IDA calls for high computational efforts and the results are highly sensitive to selected ground motions.As a result,alternative static methods are needed.This study aims to introduce a new double-stage(N1- N2) static method to estimate capacity curves of MR frames.The technique is regulated to resemble IDA results with specific emphasis on near-field ground motions.Using an ensemble of 56 near-field earthquake records,required ID As have been carried out for SAC-Los Angeles 3-,9- and 20-story buildings and an additional 15-story building.The results of the proposed static method are compared with those from IDA,displacement-based adaptive procedure(DAP),and multimodal procedure(MMP).The results indicate that in addition to enhanced accuracy,very little time is required in the case of N1-N2 method.Thus,for the 3-story structure,the time required is less than 1 minute.The proposed N1-N2 method shows the best accuracy in terms of lateral mechanisms for the 15-story frame while for the other cases,the first mode load pattern leads to the best accuracy.

Incremental Static Analysis of 2D Flow by Inter-Colliding Point-Particles and Use of Incompressible Rhombic Element

A simple method is proposed, for incremental static analysis of a set of inter-colliding particles, simulating 2D flow. Within each step of proposed algorithm, the particles perform small displacements, proportional to the out-of-balance forces, acting on them. Numerical experiments show that if the liquid is confined within boundaries of a set of inter-communicating vessels, then the proposed method converges to a final equilibrium state. This incremental static analysis approximates dynamic behavior with strong damping and can provide information, as a first approximation to 2D movement of a liquid. In the initial arrangement of particles, a rhombic element is proposed, which assures satisfactory incompressibility of the fluid. Based on the proposed algorithm, a simple and short computer program (a “pocket” program) has been developed, with only about 120 Fortran instructions. This program is first applied to an amount of liquid, contained in a single vessel. A coarse and refined discretization is tried. In final equilibrium state of liquid, the distribution on hydro-static pressure on vessel boundaries, obtained by proposed computational model, is found in satisfactory approximation with corresponding theoretical data. Then, an opening is formed, at the bottom of a vertical boundary of initial vessel, and the liquid is allowed to flow gradually to an adjacent vessel. Almost whole amount of liquid is transferred, from first to second vessel, except of few drops-particles, which remain, in equilibrium, at the bottom of initial vessel. In the final equilibrium state of liquid, in the second vessel, the free surface level of the liquid confirms that the proposed rhombing element assures a satisfactory incompressibility of the fluid.

Incremental Linear Discriminant Analysis Dimensionality Reduction and 3D Dynamic Hierarchical Clustering WSNs

Optimizing the sensor energy is one of the most important concern in Three-Dimensional(3D)Wireless Sensor Networks(WSNs).An improved dynamic hierarchical clustering has been used in previous works that computes optimum clusters count and thus,the total consumption of energy is optimal.However,the computational complexity will be increased due to data dimension,and this leads to increase in delay in network data transmission and reception.For solving the above-mentioned issues,an efficient dimensionality reduction model based on Incremental Linear Discriminant Analysis(ILDA)is proposed for 3D hierarchical clustering WSNs.The major objective of the proposed work is to design an efficient dimensionality reduction and energy efficient clustering algorithm in 3D hierarchical clustering WSNs.This ILDA approach consists of four major steps such as data dimension reduction,distance similarity index introduction,double cluster head technique and node dormancy approach.This protocol differs from normal hierarchical routing protocols in formulating the Cluster Head(CH)selection technique.According to node’s position and residual energy,optimal cluster-head function is generated,and every CH is elected by this formulation.For a 3D spherical structure,under the same network condition,the performance of the proposed ILDA with Improved Dynamic Hierarchical Clustering(IDHC)is compared with Distributed Energy-Efficient Clustering(DEEC),Hybrid Energy Efficient Distributed(HEED)and Stable Election Protocol(SEP)techniques.It is observed that the proposed ILDA based IDHC approach provides better results with respect to Throughput,network residual energy,network lifetime and first node death round.

Comparison of seismic fragility analysis methods for arch dams

This study focuses on the seismic fragility analysis of arch dams.The multiple stripe analysis(MSA),cloud analysis(CLA),and incremental dynamic analysis(IDA)methods are compared.A comprehensive dam-reservoir-foundation rock system,which considers the opening of contraction joints,the nonlinearity of dam concrete and foundation rock,the radiation damping effect of semi-unbounded foundation,and the compressibility of reservoir water,is used as a numerical example.225,80,and 15 earthquake records are selected for MSA,CLA,and IDA,respectively.The results show that MSA provides satisfactory fragility analysis,while both CLA and IDA have assumptions that may lead to deviations.Therefore,MSA is the most reliable method among the three methods and is recommended for the fragility analysis of arch dams.It is also shown that the choice of demand level affects the reliability of fragility curves and the effect of the material uncertainty on the fragility of the dam is not significant.

Analysis of Capacity Decay, Impedance, and Heat Generation of Lithium-ionBatteries Experiencing Multiple Simultaneous Abuse Conditions

Abuse of Lithium-ion batteries,both physical and electrochemical,can lead to significantly reduced operational capabilities.In some instances,abuse can cause catastrophic failure,including thermal runaway,combustion,and explosion.Many different test standards that include abuse conditions have been developed,but these generally consider only one condition at a time and only provide go/no-go criteria.In this work,different types of cell abuse are implemented concurrently to determine the extent to which simultaneous abuse conditions aggravate cell degradation and failure.Vibrational loading is chosen to be the consistent type of physical abuse,and the first group of cells is cycled at different vibrational frequencies.The next group of cells is cycled at the same frequencies,with multiple charge pulses occurring during each discharge.The final group of cells is cycled at the same frequencies,with a partial nail puncture occurring near the beginning of cycling.The results show that abusing cells with vibrational loading or vibrational loading with current pulses does not cause a significant decrease in operational capabilities while abusing cells with vibrational loading and a nail puncture drastically reduces operational capabilities.The cells with vibration only experience an increase in internal resistance by a factor of 1.09–1.26,the cells with vibration and current pulses experience an increase in internal resistance by a factor of 1.16–1.23,and all cells from each group reach their rated lifetime of 500 cycles without reaching their end-of-life capacity.However,the cells with vibration and nail puncture experience an increase in internal resistance by a factor of 6.83–22.1,and each cell reaches its end-of-life capacity within 50 cycles.Overall,the results show that testing multiple abuse conditions simultaneously provides a better representation of the extreme limitations of cell operation and should be considered for inclusion in reference test standards.

Exceeding probability analysis for rail of high-speed railway under seismic excitations

Purpose–The smoothness of the high-speed railway(HSR)on the bridge may exceed the allowable standard when an earthquake causes vibrations for HSR bridges,which may threaten the safety of running trains.Indeed,few studies have evaluated the exceeding probability of rail displacement exceeding the allowable standard.The purposes of this article are to provide a method for investigating the exceeding probability of the rail displacement of HSRs under seismic excitation and to calculate the exceeding probability.Design/methodology/approach–In order to investigate the exceeding probability of the rail displacement under different seismic excitations,the workflow of analyzing the smoothness of the rail based on incremental dynamic analysis(IDA)is proposed,and the intensity measure and limit state for the exceeding probability analysis of HSRs are defined.Then a finite element model(FEM)of an assumed HSR track-bridge system is constructed,which comprises a five-span simply-supported girder bridge supporting a finite length CRTS II ballastless track.Under different seismic excitations,the seismic displacement response of the rail is calculated;the character of the rail displacement is analyzed;and the exceeding probability of the rail vertical displacement exceeding the allowable standard(2mm)is investigated.Findings–The results show that:(1)The bridge-abutment joint position may form a step-like under seismic excitation,threatening the running safety of high-speed trains under seismic excitations,and the rail displacements at mid-span positions are bigger than that at other positions on the bridge.(2)The exceeding probability of rail displacement is up to about 44%when PGA 50.01g,which is the level-five risk probability and can be described as’very likely to happen’.(3)The exceeding probability of the rail at the mid-span positions is bigger than that above other positions of the bridge,and the mid-span positions of the track-bridge system above the bridge may be the most hazardous area for the running safety of trains under seismic excitation when high-speed trains run on bridges.Originality/value–The work extends the seismic hazardous analysis of HSRs and would lead to a better understanding of the exceeding probability for the rail of HSRs under seismic excitations and better references for the alert of the HSR operation.

Prediction of Health Level of Multiform Lithium Sulfur Batteries Based on Incremental Capacity Analysis and an Improved LSTM

Capacity estimation plays a crucial role in battery management systems,and is essential for ensuring the safety and reliability of lithium-sulfur(Li-S)batteries.This paper proposes a method that uses a long short-term memory(LSTM)neural network to estimate the state of health(SOH)of Li-S batteries.The method uses health features extracted from the charging curve and incre-mental capacity analysis(ICA)as input for the LSTM network.To enhance the robustness and accuracy of the network,the Adam algorithm is employed to optimize specific hyperparameters.Experimental data from three different groups of batteries with varying nominal capac-ities are used to validate the proposed method.The results demonstrate the effectiveness of the method in accurately estimating the capacity degradation of all three batteries.Also,the study examines the impact of different lengths of network training sets on capacity estimation.The results reveal that the ICA-LSTM model achieves a prediction accuracy of mean absolute error 4.6%and mean squared error 0.21%with three different training set lengths of 20%,40%,and 60%.The analysis demonstrates that the lightweight model maintains high SOH estimation accu-racy even with a small training set,and exhibits strong adaptive and generalization capabilities when applied to different Li-S batteries.Overall,the proposed method,supported by experimental validation and analysis,demonstrates its efficacy in ensuring accurate and reliable SOH estimation,thereby enhancing the safety and per-formance of Li-S batteries.Index Terms—Adam algorithm,incremental capacity analysis,Li-S battery,long short-term memory,state of health.

Seismic response characteristics of nuclear island structure at generic soil and rock sites

The number of traditionally excellent coastal lithologic nuclear power plants is limited.It is a trend to develop nuclear power plants on soil sites in inland areas.Therefore,the seismic safety and adaptability of non-rock nuclear power plant(NPP)sites are the key concerns of nuclear safety researchers.Although the five site categories are clearly defined in the AP1000 design control documents,the effects of nuclear power five site conditions and soil nonlinearity on the seismic response characteristics of nuclear island buildings have not been systematically considered in previous related studies.In this study,targeting the AP1000 nuclear island structure as the research object,three-dimensional finite element models of a nuclear island structure at five types of sites(firm rock site(FR),soft rock site(SR),soft-to-medium soil site(SMS),upper bound soft-to-medium site(SMS-UB),and soft soil site(SS))are established.The partitioned analysis method of soil-structure interaction(PASSI)in the time-domain is used to investigate the effects of site hardness and nonlinearity on the acceleration,displacement,and acceleration response spectrum of the nuclear island structure under seismic excitation.The incremental equilibrium equation and explicit decoupling method are used to analyze the soil nonlinearity described by the Davidenkov model with simplified loading-reloading rules.The results show that,in the linear case,with the increase of site hardness,the peak ground acceleration(PGA)and the peak of acceleration response spectrum of the nuclear island structure increase except for the FR site,while the maximum displacement decreases.In nonlinear analysis,as the site hardness increases,the PGA,maximum displacement,and the peak of acceleration response spectrum of the nuclear island structure increase.The peak value of the acceleration response spectrum in the nonlinear case is greater than that in the linear case for FR,while smaller for SR and soil sites.The site nonlinearity reduces the peak values of the response spectrum for SR and soil sites much more as the site hardness decreases.The results of this study can provide a reference for design of nuclear island structures on soil and rock sites.

Labor Allocation Effect on China's Economic Growth

Since the reform and opening up in 1978, the improving efficiency of resource allocation, particularly the flow and migration of agricultural workforce to non-agricultural sectors, has contributed greatly to China's economic growth. However, scholars have seldom carried out continuous empirical study on the extent of such contribution mainly due to limited methods for the calculation of labor allocation effect. This paper employs the incremental analysis method of index to separate labor allocation effect from economic growth in order to conduct an analysis on such effect under the framework of economic growth. Using this approach, this paper has calculated the labor allocation effect during various periods of time in China between 1978 and 2014 and the results indicate that the flow and migration of labor constituted the major source of China's economic growth during the periods between 1978 and 1987, between 1992 and 1998 and between 2003 and 2014 and still have great potentials in the coming decade. After 2025, the labor allocation effect will diminish and is likely to become a factor that hinders economic growth.

Evaluation of collapse resistance of RC frame structures for Chinese schools in seismic design categories B and C

According to the Code for Seismic Design of Buildings （GB50011-2001）, ten typical reinforced concrete （RC） frame structures, used as school classroom buildings, are designed with different seismic fortification intensities （SFIs） （SFI=6 to 8.5） and different seismic design categories （SDCs） （SDC=B and C）. The collapse resistance of the frames with SDC=B and C in terms of collapse fragility curves are quantitatively evaluated and compared via incremental dynamic analysis （IDA）. The results show that the collapse resistance of structures should be evaluated based on both the absolute seismic resistance and the corresponding design seismic intensity. For the frames with SFI from 6 to 7.5, because they have relatively low absolute seismic resistance, their collapse resistance is insufficient even when their corresponding SDCs are upgraded from B to C. Thus, further measures are needed to enhance these structures, and some suggestions are proposed.

Vulnerability of ordinary moment resistant concrete frames

The effects of structural modeling （bar slip in lap splice）, ground motion selection process （epsilon effect） and size of a structure （number of bays and stories） on the fragility of reinforced concrete ordinary moment resisting frames are investigated. An analytical model is developed to account for bar slip in lap splice, which exhibits good correlation with existing experimental data. Then, incremental dynamic analysis is used to derive the fragility curves for four model structures. The model structures simulate frames with a different number of bays and stories. Finally, the fragility curves are corrected for the epsilon effect. The results show that slip in the lap splice can significantly increase the failure probability, especially for the collapse prevention limit state. At the same time, it is found that spectral shape has a significant impact on the fragility curves. It is also found that accounting for or ignoring bar slip or epsilon effects increases the probability of failure for larger structures. This indicates an unconservative bias in the safety of larger structures.

Development of fragility curves by incorporating new spectral shape indicators and a weighted damage index:case study of steel braced frames in the city of Mashhad,Iran

In this study, strong ground motion record （SGMR） selection based on Eta （~/） as a spectral shape indicator has been investigated as applied to steel braced flame structures. A probabilistic seismic hazard disaggregation analysis for the definition of the target Epsilon （ε） and the target Eta （η） values at different hazard levels is presented, taking into account appropriately selected SGMR＇s. Fragility curves are developed for different limit states corresponding to three representative models of typical steel braced frames having significant irregularities in plan, by means of a weighted damage index. The results show that spectral shape indicators have an important effect on the predicted median structural capacities, and also that the parameter r/is a more robust predictor of damage than searching for records with appropriate c values.

Seismic performance evaluation of a self-centering precast reinforced concrete frame structure

The seismic performance of a five-story,four-bay,self-centering precast reinforced concrete frame(SC-RCF),which was redesigned using the direct displacement-based design method,was analytically investigated.The analytical model of the overall structure was developed in OpenSees.The multi-spring contact element was adopted to simulate gap open-close behavior at connection interfaces.The limit states of external mild steel dampers and unbonded post-tensioning strands were considered.Static pushover analyses were performed up to the roof drift of 10%.The nonlinear dynamic responses under four groups of ground motions(with different fault distances and site conditions)at six hazard levels(from the service to the very rare earthquake(VRE))were compared.Incremental dynamic analyses were implemented to quantify the structural collapse risk.The results showed that the structural responses of SC-RCF were satisfactory under all levels of earthquakes.The collapse safety of the structure under earthquakes up to VRE1 was adequate,while the structure would collapse to a large extent under VRE2 and VRE3.

Performance-based seismic financial risk assessment of reinforced concrete frame structures

Engineering facilities subjected to natural hazards(such as winds and earthquakes) will result in risk when any designed system(i.e.capacity) will not be able to meet the performance required(i.e.demand).Risk might be expressed either as a likelihood of damage or potential financial loss.Engineers tend to make use of the former(i.e.damage).Nevertheless,other non-technical stakeholders cannot get useful information from damage.However,if financial risk is expressed on the basis of probable monetary loss,it will be easily understood by all.Therefore,it is necessary to develop methodologies which communicate the system capacity and demand to financial risk,Incremental dynamic analysis(IDA) was applied in a performance-based earthquake engineering context to do hazard analysis,structural analysis,damage analysis and loss analysis of a reinforced concrete(RC) frame structure.And the financial implications of risk were expressed by expected annual loss(EAL).The quantitative risk analysis proposed is applicable to any engineering facilities and any natural hazards.It is shown that the results from the IDA can be used to assess the overall financial risk exposure to earthquake hazard for a given constructed facility.The computational IDA-EAL method will enable engineers to take into account the long-term financial implications in addition to the construction cost.Consequently,it will help stakeholders make decisions.