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.

Effects of virtual agents on interaction efficiency and environmental immersion in MR environments

Background Physical entity interactions in mixed reality(MR)environments aim to harness human capabilities in manipulating physical objects,thereby enhancing virtual environment(VEs)functionality.In MR,a common strategy is to use virtual agents as substitutes for physical entities,balancing interaction efficiency with environmental immersion.However,the impact of virtual agent size and form on interaction performance remains unclear.Methods Two experiments were conducted to explore how virtual agent size and form affect interaction performance,immersion,and preference in MR environments.The first experiment assessed five virtual agent sizes(25%,50%,75%,100%,and 125%of physical size).The second experiment tested four types of frames(no frame,consistent frame,half frame,and surrounding frame)across all agent sizes.Participants,utilizing a head mounted display,performed tasks involving moving cups,typing words,and using a mouse.They completed questionnaires assessing aspects such as the virtual environment effects,interaction effects,collision concerns,and preferences.Results Results from the first experiment revealed that agents matching physical object size produced the best overall performance.The second experiment demonstrated that consistent framing notably enhances interaction accuracy and speed but reduces immersion.To balance efficiency and immersion,frameless agents matching physical object sizes were deemed optimal.Conclusions Virtual agents matching physical entity sizes enhance user experience and interaction performance.Conversely,familiar frames from 2D interfaces detrimentally affect interaction and immersion in virtual spaces.This study provides valuable insights for the future development of MR systems.

A High-Accuracy Curve Boundary Recognition Method Based on the Lattice Boltzmann Method and Immersed Moving Boundary Method

Applying numerical simulation technology to investigate fluid-solid interaction involving complex curved bound-aries is vital in aircraft design,ocean,and construction engineering.However,current methods such as Lattice Boltzmann(LBM)and the immersion boundary method based on solid ratio(IMB)have limitations in identifying custom curved boundaries.Meanwhile,IBM based on velocity correction(IBM-VC)suffers from inaccuracies and numerical instability.Therefore,this study introduces a high-accuracy curve boundary recognition method(IMB-CB),which identifies boundary nodes by moving the search box,and corrects the weighting function in LBM by calculating the solid ratio of the boundary nodes,achieving accurate recognition of custom curve boundaries.In addition,curve boundary image and dot methods are utilized to verify IMB-CB.The findings revealed that IMB-CB can accurately identify the boundary,showing an error of less than 1.8%with 500 lattices.Also,the flow in the custom curve boundary and aerodynamic characteristics of the NACA0012 airfoil are calculated and compared to IBM-VC.Results showed that IMB-CB yields lower lift and drag coefficient errors than IBM-VC,with a 1.45%drag coefficient error.In addition,the characteristic curve of IMB-CB is very stable,whereas that of IBM-VC is not.For the moving boundary problem,LBM-IMB-CB with discrete element method(DEM)is capable of accurately simulating the physical phenomena of multi-moving particle flow in complex curved pipelines.This research proposes a new curve boundary recognition method,which can significantly promote the stability and accuracy of fluid-solid interaction simulations and thus has huge applications in engineering.

A Computational Framework for Parachute Inflation Based on Immersed Boundary/Finite Element Approach

A computational framework for parachute inflation is developed based on the immersed boundary/finite element approach within the open-source IBAMR library.The fluid motion is solved by Peskin's diffuse-interface immersed boundary(IB)method,which is attractive for simulating moving-boundary flows with large deformations.The adaptive mesh refinement technique is employed to reduce the computational cost while retain the desired resolution.The dynamic response of the parachute is solved with the finite element approach.The canopy and cables of the parachute system are modeled with the hyperelastic material.A tether force is introduced to impose rigidity constraints for the parachute system.The accuracy and reliability of the present framework is validated by simulating inflation of a constrained square plate.Application of the present framework on several canonical cases further demonstrates its versatility for simulation of parachute inflation.

Numerical Investigation on Thermal Performance of Two-Phase Immersion Cooling Method for High-Power Electronics

The power density of electronic components grows continuously,and the subsequent heat accumulation and temperature increase inevitably affect electronic equipment’s stability,reliability and service life.Therefore,achieving efficient cooling in limited space has become a key problem in updating electronic devices with high performance and high integration.Two-phase immersion is a novel cooling method.The computational fluid dynamics(CFD)method is used to investigate the cooling performance of two-phase immersion cooling on high-power electronics.The two-dimensional CFD model is utilized by the volume of fluid(VOF)method and Reynolds StressModel.Lee’s model was employed to calculate the phase change rate.The heat transfer coefficient along the heatedwalls and the shear-lift force on bubbles are calculated.The simulation data are verified with the literature results.The cooling performance of different coolants has been studied.The results indicate that the boiling heat transfer coefficient can be enhanced by using a low boiling point coolant.The methanol is used as the cooling medium for further research.In addition,the mass flow rate and inlet temperature are investigated to assess the thermal performance of twophase immersion cooling.The average temperature of the high-power electronics is 80℃,and the temperature difference can be constrained to 8℃.Meanwhile,the convective heat transfer coefficient reaches 2740 W/(m2・℃)when the inlet temperature is 50℃,and the mass flow rate is 0.3 kg/s.In conclusion,the results demonstrated that two-phase immersion cooling has provided an effective method for the thermal management of high-power electronics.

Isometric Immersions of Lightlike Warped Product Manifolds

In this paper, we deal with isommetric immersions of globally null warped product manifolds into Lorentzian manifolds with constant curvature c in codimension k≥3. Under the assumptions that the globally null warped product manifold has no points with the same constant sectional curvature c as the Lorentzian ambient, we show that such isometric immersion splits into warped product of isometric immersions.

Application of Immersive Media Technology in Ideological and Political Theory Courses Instruction at Shandong Vocational Colleges

This paper describes how virtual classrooms and out-of-classroom instruction can be used to help students in ideological and political theory courses strengthen their identities and improve the efficiency of their assignments.By using immersive media technology,the course is turned into a form of entertainment,enriched with content,and combined with methods such as digital video editing and manipulation to meet the needs of students in university ideological and political theory courses.Virtual reality technology can create realistic virtual environments created by computers,enabling students to perceive and manipulate a variety of virtual objects,interact with them,and create a sense of immersion in the virtual environment.Research has shown the potential benefits of using immersive media technologies and augmented reality in education.The potential of virtual reality in education has been increasingly emphasized and has been widely researched and applied.

Frequency responses of immersing tunnel element under wave actions

The immersion of large-scale tunnel elements is one of the most important working procedures in the construction of an underwater immersed tunnel. To investigate the dynamic characteristics of tunnel element in the process of immersion, based on the twin-barge immersing operation method, the frequency-domain analysis of the tunnel element motions under wave actions was made. The linear wave diffraction theory and the three-dimensional source distribution method were applied to calculate the wave loads and motion responses of the tunnel element under different incident wave conditions. In the study, movement of the two barges in the water was assumed to be small and was ignored. Cable tension was computed by the static method. On the basis of the above theories, a computer program was made, and two cases were taken to check the validity of the program. The results showed that wave loads acting on the immersed tunnel element are relatively large near the water surface, and they decrease with the increase of immersing depth of the tunnel element. Wave loads first increase, then decrease, with the increase of wave period. The motion responses of the tunnel element are also generally large near the water surface and decrease as the immersing depth increases.

Experimental Investigation on Element Immersing Process of Immersed Tube Tunnel

Bridges and tunnels are good solutions to transportation problems in large cities separated by large rivers. In bridge construction great success has been achieved in China, but large-sized immersed tube tunnel construction is still new. Element immersing is an important process of immersed tube tunnel construction. The accuracy of tunnel element positioning directly determines the quality of tunnel construction. In order to study the behavior of elements during its lowering to the sea bed, the experiments carried out in the State Key Laboratory of Ocean Engineering of Shanghai Jiaotong University. In consideration of the construction experience abroad and by reference to published papers on the Oresund tunnel in Norway-Sweden and Tokyo Bay tunnel in Japan, an element model to an appropriate scale is developed. A concise description of the model experiment wave environments is carried out, and the feasibility of two immersing strategies is studied.

Immersing Treatment of Steel Plate Surface in Steel-Aluminum Solid to Liquid Bonding

The interfacial status of the steel-aluminum solid to liquid bonding plates (their steel plate surfaces were or were not immersed in flux aqueous solution) were measured by using SEM (Scanning Electron Microscope) and X-ray diffraction . The results showed that the layer of flux (the minimum thickness was 15 μm on the steel plate surface) could protect the steel plate surface from oxidizing effectively at high temperature in solid to liquid bonding. The melt temperatUre of the flux should be lower than 580 ℃ so that it could be melted and removed completely. No. 1 flux (patent product made by the author) made up of halogeindes could also force liquid aluminum to infiltrate into steel plate surface and thus the interfacial shear strength of the bonding plate was rather large.

Transition Metal Doped MnO_x-CeO₂Catalysts by Ultrasonic Immersing for Selective Catalytic Reduction of NO with NH₃at Low Temperature

Transition metals doped Mn-based catalysts were prepared via ultrasonic immersing method for the selective catalytic reduction (SCR) of NOx from fuel gas. The Catalysts’ DeNOx efficiency and tolerance to sulfur were investigated in the paper. XRD results demonstrate high dispersion of Mn, Ce and M (Pr, Y, Zr, W) elements on TiO2 carrier, which is favor for reduction of active materials content. Mn-Ce-W catalyst presents uniform particle size about 500 nm to 800 nm from SEM pictures and shows the best NOx conversion of 93.2% at 200°C and 98.4% at 250°C, respectively. Sulfur tolerance analysis indicated that transition metals M can improve the catalysts’ performance when 0.01% SO2 exists in the fuel gas, because metal doping into the Mn-Ce catalyst can inhibit the sulfate deposition, especially metal sulfate, on the catalyst, which can be seen from the Fourier infrared spectrum.

Application of immersion B-scan ultrasonography in diagnosis of complex retinal detachment,persistent hyperplastic primary vitreous and intraocular tumors

AIM:To evaluate the diagnostic value of panoramic immersion B-scan ultrasonography(Pano-immersion B-scan,PIB)in complex retinal detachment(RD),persistent hyperplastic primary vitreous(PHPV)and intraocular tumors.METHODS:The clinical data of 44 patients collected from May 2012 to December 2019 in Chinese PLA General Hospital was retrospectively studied.All of these patients underwent PIB of the eye,because it was difficult to diagnose by routine ocular fundus examination,conventional ultrasound or/and ultrasonic biomicroscope(UBM)due to opacity of refractive media,pupillary occlusion,large involvement or special location of the lesion.The imaging features of difficult cases in PIB were analyzed.The diagnosis accuracy rating of PIB were evaluated and contrasted with conventional ultrasound or UBM by the standard of intraoperative diagnosis or/and pathological results.RESULTS:According to intraoperative diagnosis or pathological results as gold standard,among the 44 cases,there were 19 cases missed diagnosis,misdiagnosed or difficult-to-diagnose by conventional ultrasound or UBM,including 4 cases of long-standing RD difficult to diagnose,4 cases misdiagnosed,and 11 cases incompletely observed or miss diagnosed.The diagnostic accuracy rate of PIB and conventional ultrasound or UBM were 100%(44/44)and 56.82%(25/44),and the sensitivity of them were 100%and 56.82%.All the patients underwent PIB and were diagnosed as RD(15 cases),retinal and choroidal detachment(4 cases),subchoroidal hematocele(1 case),vitreous opacity and/or organic membrane formation(4 cases),PHPV(12 cases),iris and/or ciliary body tumors(3 cases),and choroidal tumors(6 cases).According to the intraoperative diagnosis or pathological results,the diagnostic coincidence rate of PIB was 100%,which was significantly higher than conventional ultrasound and UBM.CONCLUSION:PIB can help to accurately diagnose complex RD,PHPV,and intraocular masses with special location or/and excessive size.It has important diagnostic value for patients with equivocal findings at conventional ultrasound examination.

Improving resolution of superlens based on solid immersion mechanism

Super-resolution imaging with superlens has been one of the fundamental research topics. Unfortunately, the resolution of superlens is inevitably restrained by material loss. To address the problem, we introduce the solid immersion mechanism into the slab superlens and the cylindrical superlens. The proposed solid immersion slab superlens(SISSL) and the solid immersion cylindrical superlens(SICSL) can improve the resolution by converting evanescent wave to propagating wave using high refractive index materials. From the perspective of applications, the cylindrical superlens with finite cross section and the ability of magnification or demagnification has more advantages than the slab superlens. Therefore,we focus on demonstrating analytically the super-resolution imaging of SICSL. Due to the impedance mismatching caused by solid immersion mechanism, the whispering gallery modes(WGMs) are excited between SICSL and the air interface.We clarify the excitation conditions of WGMs and analyze their influence on the imaging quality of SICSL. The SISSL and SICSL may pave a way to apply in lithography technique and real-time biomolecular imaging in future.

Fully Immersing Water-Cooled Radial Slab Laser and its Incoherent Beam Combination

A novel scheme of fully immersing water cooling is proposed for a Nd：glass radial slab laser. The slab medium is entirely immersed in the circulating water Ailing the pumping cavity, which enables much lower temperature and reasonably smaller thermal gradient in the slab medium. The radial slab is symmetrically and synchronously pumped by eight flash lamps, and produces multi-output beams with a total energy of 469md. Incoherent beam combination property of the multi-output beams is also investigated. The approach suggested here provides a way of scaling the slab lasers to much higher output levels and also a convenience for beam combinations.

An Overview of Interactive Immersive Services

Immersive services are the typical emerging services in current IMT-2020 network.With the development of network evolution,real-time interactive applications emerge one after another.This article provides an overview on immersive services which focus on real-time interaction.The scenarios,framework,requirements,key technologies,and issues of interactive immersive service are presented.

Geographical Information Visualization on a Panoramic Sphere in an Immersive Environment

In this paper,we propose a novel approach to visualizing global geographical information:a panoramic sphere in an immersive environment.The whole geographical surface can be observed through the rotating of heads as the viewpoint of the panoramic sphere is inside the sphere.We compared three approaches to visualizing the earth for rendering the geographical information in a virtual reality environment.On the tasks of terrestrial and marine geographical information,we compare the visualization effects on a)a globe,b)a flat map and c)a panoramic sphere.Terrestrial geographical information tasks include the area comparison and direction determination.Marine geographical information tasks contain the visualization of sea surface temperature and sea surface currents.For terrestrial geographical information tasks,the experimental results show that the panoramic sphere outperforms the globe and the flat map,with a higher average accuracy and a shorter time.On marine geographical information task,the panoramic sphere visualization is also superior to the flat map and the globe in an immersive environment for the sea surface temperature data and the sea surface current fields.In all three visualization experiments,the panoramic sphere is most preferred by the participants,particularly for global,transcontinental and transoceanic needs.

Intelligent BCI Headphone for a Healthier and a Deeper Immersive Gameplay

The developments in the area of brain research by analysing brain activity of individuals have given rise to many useful applications, such as diagnosing mental disorders more efficiently, treatment of cognitive disorders, and developing of brain-computer interfaces for treatment, communication and entertainment purposes. However, the development of such applications is hindered by a shortage of easy-to-use and comfortable sensors, as well as a lack of high-quality brain activity data. In the first part of this paper, a review of the status of BCI applications is presented followed by a proposal of a framework for developing an intelligent BCI headphone that takes leverages of the huge amount of data coming from playing video games to let the players experience a full immersive gaming experience.

Beyond the horizon:immersive developments for animal ecology research

More diverse data on animal ecology are now available.This“data deluge”presents challenges for both biologists and computer scientists;however,it also creates opportunities to improve analysis and answer more holistic research questions.We aim to increase awareness of the current opportunity for interdisciplinary research between animal ecology researchers and computer scientists.Immersive analytics(IA)is an emerging research field in which investigations are performed into how immersive technologies,such as large display walls and virtual reality and augmented reality devices,can be used to improve data analysis,outcomes,and communication.These investigations have the potential to reduce the analysis effort and widen the range of questions that can be addressed.We propose that biologists and computer scientists combine their efforts to lay the foundation for IA in animal ecology research.We discuss the potential and the challenges and outline a path toward a structured approach.We imagine that a joint effort would combine the strengths and expertise of both communities,leading to a well-defined research agenda and design space,practical guidelines,robust and reusable software frameworks,reduced analysis effort,and better comparability of results.

图书馆沉浸式阅读推广模式构建及优化策略——以长沙市图书馆为例

文章结合长沙市图书馆沉浸式阅读推广实践,基于沉浸式体验的9个要素及图书馆阅读推广的设计、实施、反馈3个阶段,构建图书馆沉浸式阅读推广模式,并提出图书馆沉浸式阅读推广优化策略,即分层分级明确目标,激发读者的思维沉浸;创新阅读推广场景,强化读者主动参与意识;增强读者心流体验,持续提高活动的吸引力。

沉浸式演艺的空间生产与价值表达研究

以列斐伏尔空间生产理论为基础,沉浸式演艺中的个体在空间中表现为“沉浸在场”这一新型在场方式,基于其形式、内容和作用特征,沉浸式演艺的复合媒介、叙事文本和互动体验这三大要素相互交织、共同作用,构成介质空间、叙事空间和应答空间“三位一体”的空间生产机制,在个体与空间的双向互动过程中建构起沉浸式演艺的空间价值,通过场景塑造、合理应用科技激发空间效能,内容表达、彰显空间的文化价值,主题IP培育、构建文化传播话语体系这三方面实现沉浸式演艺的价值表达。