Comparative Analysis of ARIMA and LSTM Model-Based Anomaly Detection for Unannotated Structural Health Monitoring Data in an Immersed Tunnel

Structural Health Monitoring(SHM)systems have become a crucial tool for the operational management of long tunnels.For immersed tunnels exposed to both traffic loads and the effects of the marine environment,efficiently identifying abnormal conditions from the extensive unannotated SHM data presents a significant challenge.This study proposed amodel-based approach for anomaly detection and conducted validation and comparative analysis of two distinct temporal predictive models using SHM data from a real immersed tunnel.Firstly,a dynamic predictive model-based anomaly detectionmethod is proposed,which utilizes a rolling time window for modeling to achieve dynamic prediction.Leveraging the assumption of temporal data similarity,an interval prediction value deviation was employed to determine the abnormality of the data.Subsequently,dynamic predictive models were constructed based on the Autoregressive Integrated Moving Average(ARIMA)and Long Short-Term Memory(LSTM)models.The hyperparameters of these models were optimized and selected using monitoring data from the immersed tunnel,yielding viable static and dynamic predictive models.Finally,the models were applied within the same segment of SHM data,to validate the effectiveness of the anomaly detection approach based on dynamic predictive modeling.A detailed comparative analysis discusses the discrepancies in temporal anomaly detection between the ARIMA-and LSTM-based models.The results demonstrated that the dynamic predictive modelbased anomaly detection approach was effective for dealing with unannotated SHM data.In a comparison between ARIMA and LSTM,it was found that ARIMA demonstrated higher modeling efficiency,rendering it suitable for short-term predictions.In contrast,the LSTM model exhibited greater capacity to capture long-term performance trends and enhanced early warning capabilities,thereby resulting in superior overall performance.

Constitutive Behavior of the Interface between UHPC and Steel Plate without Shear Connector:From Experimental to Numerical Study

The application of ultra-high performance concrete(UHPC)as a covering layer for steel bridge decks has gained widespread popularity.By employing a connection without a shear connector between the steel plate and UHPC,namely,the sandblasted interface and the epoxy adhesive with sprinkled basalt aggregate interface,the installation cannot only be simplified but also the stress concentration resulting from the welded shear connectors can be eliminated.This study develops constitutive models for these two interfaces without shear connectors,based on the interfacial pull-off and push-out tests.For validation,three-point bending tests on the steel-UHPC composite plates are conducted.The results indicated that the proposed bilinear traction-separation model for the sandblasted interface and the trapezoidal traction-separation model for the epoxy adhesive with sprinkled basalt aggregate interface can generally calibrate the interfacial behavior.However,the utilization of the experimentally determined pure shear strength underestimates the load-carrying capacity of the composite plates in the case of three-point bending tests.By recalling the Mohr-Coulomb criterion,this underestimation is attributed to the enhancement of the interface shear strength by the presence of normal stress.

Composite solid electrolyte of Na3PS4-PEO for all-solid-state SnS2/Na batteries with excellent interfacial compatibility between electrolyte and Na metal

High ionic conductivity and superior interfacial stability of solid electrolytes at the electrodes are crucial factors for high-performance all-solid-state sodium batteries. Herein, a composite solid electrolyte Na3PS4-polyethylene oxide is synthesized by the solution-phase reaction method with an improved ionic conductivity up to 9.4 × 10-5 S/cm at room temperature. Moreover, polyethylene oxide polymer layer is wrapped homogeneously on the surface of Na3PS4 particles, which could effectively avoid the direct contact between Na3PS4 electrolyte and sodium metal, thus alleviate their side reactions. We demonstrate that all-solid-state battery SnS2/Na with the composite solid electrolyte Na3PS4-polyethylene oxide delivers an enhanced electrochemical performance with 230 m Ah/g after 40 cycles.

Transcriptomic and metabolomic analyses reveal that exogenous strigolactones alleviate the response of melon root to cadmium stress

Strigolactones(SLs)are classified into plant hormones,playing a key role as a mediator of plant growth in response to several abiotic stresses.Cadmium(Cd),a common heavy metal and soil pollutant,can suppress plant growth and development.In this work,we explored the effects of exogenous SLs on root formation in response to Cd stress using melon seeds subjected to seven germination treatments:CK(control),Cd(300 μmol·L^(-1) CdCl_(2)),and SL1-SL5(CdCl_(2)-stressed seeds pretreated with 0.1,0.5,1,2,and 3 μmol·L^(-1) GR24 solutions).The results indicated that SLs increased the antioxidant enzyme activities and root vigor and decreased the malondialdehyde(MDA)contents in the roots of Cdstressed melon seedlings.Then we used transcriptomic and metabolomic analyses to explore the mechanisms by which exogenous SLs protect against Cd stress.There were 242 significant differentially expressed genes(DEGs)(78 upregulated,164 downregulated)and 247 significantly differentially expressed metabolites(DEMs)(222 upregulated,25 downregulated)between the Cd and SL3 treatments.SLs altered the expression of genes related to redox formation processes,including peroxidase(POD),lipoxygenase(LOX),glutamate dehydrogenase(GDH),and glutathione S-transferase(GST).In addition,we found that SLs regulated the expression of the MYB,AP2/ERF,bHLH,and WRKY transcription factor families.The combined transcriptomic and metabolomic analyses revealed that the DEGs and DEMs involved in Cd stress alleviation were mainly related to the gene expression of jasmonic acid(JA)and flavonoid biosynthesis.SLs might induce LOX-related genes to regulate JA biosynthesis.Moreover,SLs might promote flavonoid biosynthesis by regulating eleven flavonoid-related genes and eight metabolites.The results provide a new perspective for studying the adaptation of plants to Cd stress.

Analysis Method of Transient Temperature Field for Fuel Tank ofHigh-Altitude Large UAV

Based on the analysis of factors affecting transient temperature field of aircraft fuel tank and coupled heat transfer mechanism,a mathematical model of transient coupled heat transfer,including the dynamic change of fuel quality,the internal heat transfer,the external aerodynamic convection and the radiation heat transfer,is established. Taking the aerodynamic convection and radiation heat transfer outside the tank as the third kinds of thermal boundary conditions for the thermal analysis of the fuel tank,calculation of internal and external coupling heat of fuel tank is decoupled. Thermal network method combined with hierarchical dynamic grid is used to deal with the fuel consumption,and carry on the heat transfer analysis of the fuel tank. The numerical method for the transient temperature field of aircraft fuel tank is established. Through the simulation calculation,the transient temperature distribution of the fuel tank under different flight conditions is obtained,and the influence of the fuel mass and the external thermal environment on the temperature field is analyzed.

Inversion Methods of Optical Constants of Semitransparent Solid Materials from Transmittance Spectrograms

The direct calculation models of spectral transmittance of single and double slabs consisted of semitransparent solid materials were developed based on ray trace method,and a new inversion method of optical constants ( k is extinction coefficient and n is refractive index) of materials was proposed based on transmittance spectrograms of double slabs. Differences between the new method and two others currently used methods were studied,and application range of methods was also investigated. Optical constants of selenide glass attained in references were selected as true values,and spectral transmittances of glass simulated based on direct calculation model were regarded as experimental values. Optical constants of selenide glass were achieved by inverse models. Influences of measurement error on inverse results were also determined. The results showed that: (1) based on transmittance spectrograms of double slabs in which thickness of single slab is the same,the new proposed method can attain optical constants of materials; (2) the effect of optical constants n and k on three inversion methods are urgent larger,but inversed calculation precision of optical constants are higher in most application ranges; (3) the influence of measurement errors existed in experimental datum on the inverse precision of three methods are urgent

Criticality-based quantum metrology in the presence of decoherence

Because quantum critical systems are very sensitive to the variation of parameters around the quantum phase transition(QPT),quantum criticality has been presented as an efficient resource for metrology.In this paper,we address the issue whether the divergent feature of the inverted variance is realizable in the presence of noise when approaching the QPT.Taking the quantum Rabi model(QRM)as an example,we obtain the analytical result for the inverted variance with single-photon relaxation.We show that the inverted variance may be convergent in time due to the noise.Since the precision of the metrology is very sensitive to the noise,as a remedy,we propose squeezing the initial state to improve the precision under decoherence.In addition,we also investigate the criticality-based metrology under the influence of the two-photon relaxation.Strikingly,although the maximum inverted variance still manifests a power-law dependence on the energy gap,the exponent is positive and depends on the dimensionless coupling strength.This observation implies that the criticality may not enhance but weaken the precision in the presence of two-photon relaxation,due to the non-linearity introduced by the twophoton relaxation.

Connection of the prefabricated updeck of road tunnels by a short lap-spliced joint using ultra-high-performance fiber-reinforced concrete

Prefabricated internal structures of road tunnels,consisting of precast elements and the connections between them,provide advantages in terms of quality control and manufacturing costs.However,the limited construction space in tunnels creates challenges for on-site assembly.To identify feasible connecting joints,flexural tests of precast straight beams connected by welding-spliced or lap-spliced reinforcements embedded in normal concrete or ultra-high-performance fiber-reinforced concrete(UHPFRC)are first performed and analyzed.With an improvement in the strength grade of the closure concrete for the lap-spliced joint,the failure of the beam transforms from a brittle splitting mode to a ductile flexural mode.The beam connected by UHPFRC100 with short lap-spliced reinforcements can achieve almost equivalent mechanical performance in terms of the bearing capacity,ductility,and stiffness as the beam connected by normal concrete with welding-spliced reinforcements.This favorable solution is then applied to the connection of neighboring updeck slabs resting on columns in a double-deck tunnel.The applicability is validated by flexural tests of T-shaped joints,which,fail in a ductile fashion dominated by the ultimate bearing capacity of the precast elements,similar to the corresponding straight beam.The utilization of UHPFRC significantly reduces the required lap-splice length of reinforcements owing to its strong bonding strength.

Impact of fabrication methods on binder distribution and charge transport in composite cathodes of all-solid-state batteries

The manufacturing process of all-solid-state batteries necessitates the use of polymer binders.However,these binders,being ionic insulators by nature,can adversely affect charge transport within composite cathodes,thereby impacting the rate performance of the batteries.In this work,we aim to investigate the impact of fabrication methods,specifically the solvent-free dry process versus the slurry-cast wet process,on binder distribution and charge transport in composite cathodes of solid-state batteries.In the dry process,the binder forms a fibrous network,while the wet process results in binder coverage on the surface of cathode active materials.The difference in microstructure leads to a notable 20-fold increase in ionic conductivity in the dry-processed cathode.Consequently,the cells processed via the dry method exhibit higher capacity retention of 89%and 83%at C/3 and C/2 rates,respectively,in comparison to 68%and 58%for the wet-processed cells at the same rate.These findings provide valuable insights into the influence of fabrication methods on binder distribution and charge transport,contributing to a better understanding of the binder’s role in manufacturing of all-solid-state batteries.

Coherent and incoherent theories for photosynthetic energy transfer

自然界的光合作用有一个显著的特点,即能量传递效率近乎100%.近年来,由于光合作用实验技术的飞速发展,譬如二维光谱实验和单分子泵浦探测实验,其能量传输过程中的量子相干效应已经在实验上得到了证实.传统的非相干理论能够有效计算能量转移效率,如广义的F?rster理论和修正的Redfield理论.然而,为了描述光合作用中的量子相干效应,人们必须利用量子相干理论.例如,除了传统的Redfield理论之外,还有级联运动方程、量子路径积分、相干修正的Redfield理论、小极化子量子主方程、广义Bloch-Redfield理论等.本文综述了上述方法的主要内容,不仅有助于对自然界光合作用中激子能量转移的量子动力学进行有效的量子模拟,并对人工太阳能收集装置的设计提供了一定的指导作用.

Walnut-inspired microsized porous silicon/graphene core-shell composites for high-performance lithium-ion battery anodes

Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoretical capacity and abundant storage. Here, microsized walnut-like porous silicon/reduced graphene oxide （P-Si/rGO） core-shell composites are successfully prepared via in situ reduction followed by a dealloying process. The composites show specific capacities of more than 2,100 mAh-g-1 at a current density of 1,000 mA-g-1, 1,600 mAh.g-1 at 2,000 mA-g-1, 1,500 mAh-g 1 at 3,000 mA-g-1, 1,200 mAh-g-1 at 4,000 mA.g-1, and 950 mAh.g~ at 5,000 mA.g-~, and maintain a value of 1,258 mAh.g-~ after 300 cycles at a current density of 1,000 mA-g 1. Their excellent rate performance and cycling stability can be attributed to the unique structural design： 1） The graphene shell dramatically improves the conductivity and stabilizes the solid- electrolyte interface layers; 2） the inner porous structure supplies sufficient space for silicon expansion; 3） the nanostructure of silicon can prevent the pulverization resulting from volume expansion stress. Notably, this in situ reduction method can be applied as a universal formula to coat graphene on almost all types of metals and alloys of various sizes, shapes, and compositions without adding any reagents to afford energy storage materials, graphene-based catalytic materials, graphene-enhanced composites, etc.

Establishment of age-and gender-specific pediatric reference intervals for liver function tests in healthy Han children

Background The development and growth of children influence values of liver function tests.This study aims to establish age-and gender-specific pediatric reference intervals of liver function among Han children in Changchun,China.Methods A total of 1394 healthy Han children,aged 2-14 years,were recruited from communities and schools with informed parental consent in Changchun.The levels of serum alanine aminotransferase(ALT),aspartate aminotransferase(AST),y-glutamyltransferase(GGT),alkaline phosphatase(ALP),total protein(TP),albumin(ALB),total bilirubin(TBIL)and direct bilirubin(DBIL)were measured on Hitachi 7600-210 automatic biochemical analyzer.The age-and gender-specific reference intervals were partitioned using Harris and Boyd's test and calculated using nonparametric rank method.The pediatric reference intervals were validated in five representative hospitals located in different areas in Changchun.Results All the analytes required some levels of age partitioning.Proteins(TP,ALB)and bilirubins(TBIL,DBIL)required no gender partitioning.In contrast,considerable gender partitioning was required for serum ALT,AST,GGT,and ALP.TP,TBIL,and DBIL showed steady increases,and AST showed apparent decreases over time,whereas ALT,GGT,ALP,and ALB demonstrated complex trends of change.ALT and GGT increased sharply in males from 11 to 14 years old.However,ALP declined in females from 13 to 14 years.All five laboratories passed the validation of reference intervals.Conclusions There were apparent age or gender variations of the reference intervals for liver function.When establishing pediatric reference intervals,partitioning according to age and gender is necessary.

Toward quantum teleporting living objects

In American science fiction television series Star Trek,teleporting crews from the spaceship to the surface of a planet was one of the most impressive scenes,as shown in Fig.1.Teleportation was believed to be a beautiful dream until 1993,when a seminal paper by Bennett et al.[1]showed that with the help of classical communication and quantum entanglement,a qubit can be transferred from one location to another,without moving a physical

Hyperbolic metamaterial using chiral molecules

We theoretically investigate the intra-band transitions in Mobius molecules.Due to the weak magnetic response,the relative permittivity is significantly modified by the presence of the medium while the relative permeability is not.We show that there is hyperbolic dispersion relation induced by the intra-band transitions because one of the eigen-values of permittivity possesses a different sign from the other two,while all three eigen-values of permeability are positive.We further demonstrate that the bandwidth of negative refraction is 0.165 eV for the H-polarized incident light,which is broader than the ones for inter-band transitions by 3 orders of magnitude.Moreover,the frequency domain has been shifted from ultra-violet to visible domain.Although there is negative refraction for the E-polarized incident light,the bandwidth is much narrower and depends on the incident angle.