Multi-Objective Prediction and Optimization of Vehicle Acoustic Package Based on ResNet Neural Network

Vehicle interior noise has emerged as a crucial assessment criterion for automotive NVH(Noise,Vibration,and Harshness).When analyzing the NVH performance of the vehicle body,the traditional SEA(Statistical Energy Analysis)simulation technology is usually limited by the accuracy of the material parameters obtained during the acoustic package modeling and the limitations of the application conditions.In order to effectively solve these shortcomings,based on the analysis of the vehicle noise transmission path,a multi-level objective decomposition architecture of the interior noise at the driver’s right ear is established.Combined with the data-driven method,the ResNet neural network model is introduced.The stacked residual blocks avoid the problem of gradient dis-appearance caused by the increasing network level of the traditional CNN network,thus establishing a higher-precision prediction model.This method alleviates the inherent limitations of traditional SEA simulation design,and enhances the prediction performance of the ResNet model by dynamically adjusting the learning rate.Finally,the proposed method is applied to a specific vehicle model and verified.The results show that the proposed meth-od has significant advantages in prediction accuracy and robustness.

Adaptive Multi-Feature Fusion for Vehicle Micro-Motor Noise Recognition Considering Auditory Perception

The deployment of vehicle micro-motors has witnessed an expansion owing to the progression in electrification and intelligent technologies.However,some micro-motors may exhibit design deficiencies,component wear,assembly errors,and other imperfections that may arise during the design or manufacturing phases.Conse-quently,these micro-motors might generate anomalous noises during their operation,consequently exerting a substantial adverse influence on the overall comfort of drivers and passengers.Automobile micro-motors exhibit a diverse array of structural variations,consequently leading to the manifestation of a multitude of distinctive auditory irregularities.To address the identification of diverse forms of abnormal noise,this research presents a novel approach rooted in the utilization of vibro-acoustic fusion-convolutional neural network(VAF-CNN).This method entails the deployment of distinct network branches,each serving to capture disparate features from the multi-sensor data,all the while considering the auditory perception traits inherent in the human auditory sys-tem.The intermediary layer integrates the concept of adaptive weighting of multi-sensor features,thus affording a calibration mechanism for the features hailing from multiple sensors,thereby enabling a further refinement of features within the branch network.For optimal model efficacy,a feature fusion mechanism is implemented in the concluding layer.To substantiate the efficacy of the proposed approach,this paper initially employs an augmented data methodology inspired by modified SpecAugment,applied to the dataset of abnormal noise sam-ples,encompassing scenarios both with and without in-vehicle interior noise.This serves to mitigate the issue of limited sample availability.Subsequent comparative evaluations are executed,contrasting the performance of the model founded upon single-sensor data against other feature fusion models reliant on multi-sensor data.The experimental results substantiate that the suggested methodology yields heightened recognition accuracy and greater resilience against interference.Moreover,it holds notable practical significance in the engineering domain,as it furnishes valuable support for the targeted management of noise emanating from vehicle micro-motors.

Research on Human-Vehicle-Road Friendliness Based on Improved SH-GH-ADD Control

The hub-driven virtual rail train is a novel urban transportation system that amalgamates the benefits of modern trams and buses.However,this system is plagued by issues such as decreased ride comfort and severe deformation of urban roads due to the increase in sprung mass and long-term rolling at the same position.To address these concerns and improve the human-vehicle-road friendliness of the virtual rail train,we propose an Improved Sky-Ground Hook and Acceleration-Driven Damper control(Improved SH-GH-ADD control)strategy for the semi-active suspension system.This control monitors the vibration acceleration signal of the unsprung mass in real-time and selects the mixed Sky-Hook and Acceleration-Driven Damper(SH-ADD)control or the mixed Ground-Hook and Acceleration-Driven Damper(GH-ADD)control based on the positive and negative values of the vibration acceleration of the unsprung mass.The Improved SH-GH-ADD control combines the advantages of SH-ADD control and GH-ADD control to achieve control of the sprung mass and unsprung mass in the full fre-quency band.Finally,through simulation and comparative analysis with traditional SH-ADD,GH-ADD,and mixed SH-GH control,we demonstrate the exceptional performance of the proposed algorithm.

Elucidating the Role of Mass Transfer in Electrochemical Redox Reactions on Electrospun Fibers

Mass transfer can tune the surface concentration of reactants and products and subsequently infl uence the catalytic perfor-mance.The morphology of nanomaterials plays an important role in the mass transfer of reaction microdomains,but related studies are lacking.Herein,a facile electrospinning technique utilizing cellulose was employed to fabricate a series of carbon nanofi bers with diff erent diameters,which exhibited excellent electrochemical nitrate reduction reaction and oxygen evolu-tion reaction activities.Furthermore,the microstructure of electrocatalysts could infl uence the gas-liquid-solid interfacial mass transfer,resulting in diff erent electrochemical performances.

The Cenozoic activities of Yangjiang-Yitongdong Fault: insights from analysis of the tectonic characteristics and evolution processes in western Zhujiang(Pearl) River Mouth Basin

The Yangjiang-Yitongdong Fault (YJF) is an important NW-trending regional fault, which divides the Zhujiang (Pearl) River Mouth Basin (ZRMB) into western and eastern segments. In Cenozoic, the northern continental margin of the South China Sea (SCS) underwent continental rifting, breakup, seafloor spreading and thermal subsidence processes, and the Cenozoic activities of YJF is one part of this series of complex processes. Two long NW-trending multichannel seismic profiles located on both sides of the YJF extending from the continental shelf to Continent-Ocean Boundary (COB) were used to study the tectonic and sedimentary characteristics of western ZRMB. Using the 2D-Move software and back-stripping method, we constructed the balance cross-section model and calculated the fault activity rate. Through the comprehensive consideration of tectonic position, tectonic evolution history, featured structure, and stress analysis, we deduced the activity history of the YJF in Cenozoic. The results showed that the YJF can be divided into two segments by the central uplift belt. From 65 Ma to 32 Ma, the YJF was in sinistral motion as a whole, inherited the preexisting sinistral motion of Mesozoic YJF, in which, the southern part of YJF was mainly in extension activity, controlling the formation and evolution of Yunkai Low Uplift, coupled with slight sinistral motion. From 32 Ma to 23.8 Ma, the sinistral motion in northern part of YJF continued, while the sinistral motion in southern part began to stop or shifted to a slightly dextral motion. After 23.8 Ma, the dextral motion in southern part of YJF continued, while the sinistral motion in northern part of YJF gradually stopped, or shifted to the slightly dextral motion. The shift of the YJF strike-slip direction may be related to the magmatic underplating in continent-ocean transition, southeastern ZRMB. According to the analysis of tectonic activity intensity and rift sedimentary structure, the activities of YJF in Cenozoic played a regulating role in the rift extension process of ZRMB.

满足新时代大学生科研需求的关键平台：创新研修课

中美两国本科教学有着较大的区别。与美国相比,中国管理制的教学体制有利于督促学生学习,充足的课程让学生理论功底更扎实。但中国本科教学往往强调知识内容本身,而较少关注理论的实践运用,重知识传授,轻能力培养,以致学生实践能力不足。当代大学生科研热情日益高涨,越来越多的本科生期望参与科研。哈尔滨工业大学以科研优势为依托,设立“创新研修课”,受到学生欢迎。实践证明,“创新研修课”不仅为年轻教师提供了科研助手,更为本科生搭建了通往研究生继续深造的过渡桥梁。“创新研修课”已成为本科生发表SCI学术论文的创新平台,为本科生打开了参与国际交流的一扇窗。

Risk factors of early mortality and major morbidity in adult patients after surgical repair of partial atrioventricular septal defects

Objective To investigate the risk factors for prolonged postoperative mechanical ventilation patients with atrioventricular septal defect(AVSD).Methods We retrospectively analyzed the clinical data of 76 patients with atrioventricular septal defect aged more than 18 years in our hospital from January 1^st 2011 to December 31^st 2017.

Surgical repair of intermediate atrioventricular septal defect in adults

Objective To review the results of surgical correction of intermediate atrioventricular septal defect in adults and associated cardiac comorbidities.Methods Retrospective case analysis of database of department of SICU form FuWai Hospital.Ten consecutive patients operated for intermediate atrioventricular septal defect repair from March 2013 to November 2017 were included.

广州市某三甲医院放射工作人员受照辐射剂量分析

目的掌握广州市某三甲医疗机构放射工作人员外照射个人剂量情况,为放射卫生防护管理提供科学依据。方法采用热释光剂量测量方法,对2020年广州市某三甲医疗机构的放射工作人员进行个人剂量监测,分析监测数据。结果共计182人参与个人剂量监测,其中X射线影像诊断工作人员占84.6%(154/182),介入放射学工作人员占15.4%(28/182)。四期合计监测566人次,其中X射线影像诊断工作人员470人次,介入放射学工作人员96人次。个人剂量年度监测期数满四期的人员占监测总人数的55.5%(101/182)。单个周期有效剂量在调查水平(>1.25 mSv)范围的有3人,分别为1.56 mSv、1.32 mSv、2.59 mSv。X射线影像诊断、介入放射学人均年有效剂量分别为0.42(0.27,0.93)mSv/a、0.59(0.17,0.78)mSv/a,两者相比差异无统计学意义(P>0.05)。铅衣内、外人均年有效剂量分别为0.40(0.16,0.81)mSv/a、0.72(0.29,0.91)mSv/a,差异有统计学意义(Z=-4.395,P<0.05)。介入放射学工作人员铅衣外剂量大于内剂量的情况占70.8%(68/96);铅衣内剂量大于外剂量的情况占29.2%(28/96)。结论该医院应进一步加强放射工作人员管理,降低辐射受照剂量,防止放射性疾病的发生。

Passive-source ocean bottom seismograph(OBS) array experiment in South China Sea and data quality analyses

Long-term passive source ocean bottom seismograph(OBS) observatory is challenging due to various technical difficulties. In order to gain experience in this field, and to reveal the lithospheric structure beneath the extinct ridge in the central South China Sea(SCS), we carried out a passive source OBS array experiment, which includes 18 OBSs, in the deep portion of SCS. Here we present the instrumentation, the OBS deployment and recovery of this experiment, and more importantly, the data quality evaluated by a number of approaches. Through processing and inspecting waveforms from global, regional and local earthquakes, we find that most of recovered OBSs have good data quality with discernible main phases. The ambient noise analyses of OBS recordings show that their noise is higher than the global average, and the horizontal component is noisier than the vertical, indicating current impacts on horizontal components are more severe. In the period range of 5–10 s, there is a noise notch for the SCS OBSs, and noise levels of horizontal components are comparable to the vertical. This feature, which is not seen at OBS stations in open ocean, suggests the distant sources for double frequency microseism in this marginal sea are not significant. In addition, we successfully determined the orientations for 7 OBSs by investigating their Rayleigh wave polarizations; and we demonstrated the dispersion feature of Rayleigh waves through the frequency-time analysis. Finally, we summarized lessons learned from this experiment regarding the passive source OBS investigations in SCS.

日、韩税收营商环境排名变化的原因

税收营商环境是一国整体营商环境的重要组成部分,税收营商环境的优化将有效提升企业投资热情和生产活力,推动国家经济转型、实现高质量发展。本文根据世界银行公布的日、韩两国税收营商环境数据,比较分析两国税收营商环境排名的变化趋势,归纳总结出排名变动背后所蕴含的内在机理,并从企业税费负担和纳税遵从成本角度,为优化我国税收营商环境提出相关的政策建议。

The deep thermal structure of the lithosphere in the northwestern South China Sea and its control on the shallow tectonics

The northwestern sub-basin of South China Sea(SCS)is a unique tectonic unit formed in the early spreading of the SCS.The northwestern Sub-basin has a series of complex geological structures such as seamounts and fault zones surrounded by the Xisha Trough,the Zhongsha Massif,and the Pearl River Valley.These extensional structures and magmatic activity in the northwestern sub-basin are closely related to the lithospheric structure and its deformation.However,details of the deep lithosphere structure are still poorly known.Here,we obtained detailed data of water and Moho depth using sonar buoys,Extended Spread Profiles(ESP),Ocean Bottom Seismometer(OBS),both Multi-beam and land-sea joint seismic surveys in the northwestern sub-basin and its surrounding areas.Then we adopted a thermal isostasy method to calculate the depth of the Lithosphere-Asthenosphere Boundary(LAB)in the northwestern sub-basin of the SCS and its surrounding regions.Results show that the range of LAB depth is~25–110 km.The shallowest burial depth is 25–60 km occurring in the ocean basin.The depth increases to 60–110 km toward the continental margin.The lithospheric structure on the north and south sides of the Xisha Trough is symmetrical and shows the deep structure and thermal features of aborted rifts.The LAB depth in the Zhongsha Trough and the Zhongsha Massif increased from 60 to 70 km southwestwards,consistent with the trend of surface morphology.The LAB depth to the west side of the Pearl River Valley is 60–80 km,and the thinning of the lithosphere is related to the distribution of faults,depressions and the magmatic activity.The LAB depth in the northwestern sub-basin and the eastern subbasin is less than 60 km with the thinnest part being less than 46 km.Combining ocean drilling,seismic investigation,and seafloor topography,we show that the ocean basin of the northwestern sub-basin of the SCS locates within the 46 km isobath of the LAB.The formation of the rifted valleys and discrete blocks surrounding the ocean basins is both controlled by the regional tectonic movement and the deep thermal state,where their lithospheric structures show strong heterogeneity.

Fault-controlled regional magmatism and mineral deposition in central Cathaysia——Evidence from ambient noise tomography

Guangdong Province in the central Cathaysian Block has two world-class metallogenic belts, namely, the Nanling and Southeastern Coastal Metallogenic Belts(NLMB and SCMB), which are spatially coincide with the major regional Ganjiang and Zhenghe-Dapu Fault Zones(GJFZ and ZDFZ). However, what roles the faults played in mineral deposition and magmatism is unclear. Using ambient noise tomography, we obtain a 3-D whole-crust shear wave velocity model. By combining available regional geophysical models, we characterize the architecture of the regional shallow lithosphere and infer its possible tectonic connection to magmatic sources, pathways and surface deposition. The results show that the study area is loosely divided by the two major faults, the GJFZ and ZDFZ, into distinct velocity domains. In the north high Vand low V/Vcrust in the NLMB imply crustal remelting, which leads to the general felsic composition. In the coastal area, the lower crustal high Vanomaly is attributed to upwelling melts associated with Cretaceous magmatic activity. Between mineral belts, a swath of crustal lowvelocity zones extend into the uppermost mantle, manifesting partial melting related to upwelling magmas that may hint at a deep origin of magma from subcrustal lithosphere and likely feed surface mineral deposits through major faults. Secondary NW-trending faults coincide with low velocities and facilitated magmatic migration. A correlation between coastward extension of low velocities and younging of the Jurassic and Cretaceous magmatism is suggestive of a combined effect of slab rollback and a change in the direction of the Paleo-Pacific subduction system. We speculate a regional fault-control model in the central Cathaysian Block for the spatial-temporal evolution of regional deformation and magmatism during the middle Mesozoic.

Fast Prediction of Immiscible Two-Phase Displacements in Heterogeneous Porous Media with Convolutional Neural Network

A convolutional neural network is developed for rapidly predicting multiphase flow in heterogeneous porous media.Some direct numerical methods can acquire accurate results of multiphase flow in porous media.However,once the geometry of the porous media changes,it takes much computational time to perform a new simulation.Here,a deep neural network model in the field of semantic segmentation is developed.It takes the two-dimensional microstructure of heterogeneous porous media as inputs and is able to predict corresponding multiphase flow fields(pressure and saturation fields).Compared to the direct lattice Boltzmann simulations,the inference time on new geometry of porous media can be reduced by several orders of magnitude.Our results show that the machine learning method is a good prediction tool in a wide range of porosity and heterogeneity.Besides,to better understand the inherent process,a visible explanation is presented on what our neural networks have learned.

Lattice Boltzmann Study of a Vortex Ring Impacting Spheroidal Particles

Interaction of vortex rings with solid is an important research topic of hydrodynamic.In this study,a multiple-relaxation time(MRT)lattice Boltzmann method(LBM)is used to investigate the flow of a vortex ring impacting spheroidal particles.The MRT-LBM is validated through the cases of vortex ring impacting a flat wall.The vortex evolution due to particle size,the aspect ratio of a prolate particle,as well as Reynolds(Re)number are discussed in detail.When the vortex ring impacting a stationary sphere,the primary and secondary vortex rings wrap around each other,which is different from the situation of the vortex ring impacting a plate.For the vortex ring impacting with a prolate spheroid,the secondary vortex ring stretches mainly along the long axis of the ellipsoid particle.However,it is found that after the vortex wrapping stage,the primary vortex recovers along the short axis of the particle faster than that in the long axis,i.e.,the primary vortex ring stretches mainly along the short axis of the particle.That has never been address in the literature.

Multifunctional Polypyrrole-silver Coated Layered Double Hydroxides Embedded into a Biodegradable Polymer Matrix for Enhanced Antibacterial and Gas Barrier Properties

In this study,polypyrrole-silver coated layered double hydroxides(LDHs@PPy-Ag)was prepared by chemical polymerization of pyrrole(Py)with silver ions.Silver nanoparticles(AgNPs)could be uniformly reduced onto PPy coatings in situ by redox reaction during simultaneous polymerization process.And LDHs@PPy-Ag/poly(ε-caprolactone)(PCL)nanocomposites were fabricated by solution casting method.It is revealed that spherical AgNPs are loaded on PPy coatings uniformly.Particularly,compared with pure PCL,LDHs@PPy-Ag/PCL nanocomposites with incorporation of only 1 wt%LDHs@PPy-Ag show a 17%increase in tensile strength(36.5 MPa)and a 29%increase in elongation at break(822%).Upon PPy-Ag coatings onto original LDHs,oxygen relative permeability of LDHs@PPy-Ag/PCL nanocomposites decreases to 52%with the same addition.Meanwhile,due to the double antibacterial activity of PPy and AgNPs,the antibacterial rate of LDHs@PPy-Ag reaches 100%.And the corresponding LDHs@PPy-Ag/PCL nanocomposites also show outstanding antibacterial activity.Considering the superiority of their comprehensive performance,antibacterial LDHs@PPy-Ag/PCL nanocomposites can be used further for the application as biodegradable polymeric active packaging materials.

Simplified fabrication of high areal capacitance all-solid-state micro-supercapacitors based on graphene and MnO_2 nanosheets

All-solid-state micro-supercapacitors are acknowledged as a very promising class of microscale energy storage devices for directly integrating portable and wearable electronics. However, the improvement of electrochemical performance from materials to devices still remains tremendous challenges. Here, we demonstrate a novel and universal mask-assisted filtration technology for the simplified fabrication of all-solid-state planar micro-supercapacitors（MSCs） based on interdigital patterns of 2D pseudocapacitive MnO2 nanosheets and electrochemically exfoliated graphene film as both electrode and current collector, and polyvinyl alcohol/Li Cl gel as electrolyte. Remarkably, the resulting MSCs exhibit outstanding areal capacitance of ～355 m F/cm^2, which is among the highest values reported in the state-of-the-art MSCs. Meanwhile, MSCs possess exceptionally mechanical flexibility as high as ～92% of initial capacitance even at a highly bending angle of 180°, excellent cyclability with a capacitance retention of 95% after 3000 cycles, and impressive serial or parallel integration for modulating the voltage or capacitance. Therefore, our proposed strategy of simplified construction of MSCs will pave the ways for utilizing graphene and analogous pseudocapactive nanosheets in high-performance MSCs.

基于金属-有机框架同分异构体构建MOFs相结用以增强CO_(2)光还原活性

利用太阳能将CO_(2)光转化为化学燃料是前沿研究的热点.当前,科研的重点在于开发和优化各类光催化材料的性能.异质结构不仅用于增强无机半导体催化剂的活性,而且用于金属-有机框架(MOFs)光催化剂的构建.随着异质结技术的不断进步,新的相结概念应运而生.尽管关于无机半导体中的相结研究已取得一定进展,但是MOFs相结结构的探索尚处于起步阶段.本文中,我们成功设计并构建了一种具有卓越光催化CO_(2)还原性能的MOFs相结杂化材料.这种材料由具有高度连接性的卟啉配体(TCPP-Ni)与Zr6团簇紧密结合而成,在溶剂热反应条件下,PCN-222-Ni能够快速且均匀地成核.通过精准调控调节剂的用量,我们实现了同分异构体PCN-224-Ni在类似条件下较慢的晶体形成过程.最终制得的P@P杂化材料展现出高表面积、多孔性和卓越的结晶度.由于PCN-222-Ni和PCN-224-Ni之间的带隙匹配,光生载流子的分离和迁移得以促进,从而使P@P杂化材料展现出卓越的光还原CO_(2)性能.这一重大突破不仅标志着MOFs相结结构研究的重大进展,还拓宽了MOFs相结在CO_(2)光转化领域的应用前景.