bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of a giant meteorite impact on Paleoarchean surface environments and life
Authors: Drabon Nadja , Knoll Andrew H. , Lowe Donald R. , Bernasconi Stefano M. , Brenner Alec R. , Mucciarone David A.
Published: October 2024

Large meteorite impacts must have strongly affected the habitability of the early Earth. Rocks of the Archean Eon record at least 16 major impact events, involving bolides larger than 10 km in diameter. These impacts probably had severe, albeit temporary, consequences for surface environments. However, their effect on early life is not well understood. Here, we analyze the sedimentology, petrography, and carbon isotope geochemistry of sedimentary rocks across the S2 impact event (37 to 58 km carbonaceous chondrite) forming part of the 3.26 Ga Fig Tree Group, South Africa, to evaluate its environmental effects and biological consequences. The impact initiated 1) a giant tsunami that mixed Fe
2+
-rich deep waters into the Fe
2+
-poor shallow waters and washed debris into coastal areas, 2) heating that caused partial evaporation of surface ocean waters and likely a short-term increase in weathering and erosion on land, and 3) injection of P from vaporization of the S2 bolide. Strata immediately above the S2 impact event contain abundant siderites, which are associated with organic matter and exhibit light and variable δ
13
C
carb
values. This is consistent with microbial iron cycling in the wake of the impact event. Thus, the S2 impact likely had regional, if not global, positive and negative effects on life. The tsunami, atmospheric heating, and darkness would likely have decimated phototrophic microbes in the shallow water column. However, the biosphere likely recovered rapidly, and, in the medium term, the increase in nutrients and iron likely facilitated microbial blooms, especially of iron-cycling microbes.
Tolerance and efficient metabolization of extremely high ethanol concentrations by a social wasp
Authors: Bouchebti Sofia , Gershon Yael , Gordin Alexander , Huchon Dorothée , Levin Eran
Published: October 2024

Ethanol, a natural by-product of sugar fermentation, can be found in various fruits and nectar. Although many animals routinely consume ethanol in low concentrations as part of their natural diets, its inherent toxicity can cause severe damage. Even species particularly well adapted to ethanol consumption face detrimental effects when exposed to concentrations above 4%. Here, we investigated the metabolism of ethanol and its impact on survival and behavior in the Oriental hornet (
Vespa orientalis
), a social wasp that naturally consumes ethanol. We show that chronic ethanol consumption, even at concentrations as high as 80%, had no impact on hornet mortality, construction behavior, or agonistic behavior. Using
13
C1 labeled ethanol, we show that hornets efficiently metabolized ingested ethanol and at a much higher rate than honey bees. The presence of multiple copies of the alcohol dehydrogenase (NADP+) gene in the
Vespa
genera suggests a potential mechanism for ethanol tolerance. These findings support the hypothesis that the mutualistic relationship between ethanol-producing organisms and vespid hosts may be at the origin of their remarkable capacity to utilize and metabolize ethanol.
Theropod trackways as indirect evidence of pre-avian aerial behavior
Authors: Dececchi T. Alexander , Kim Kyung Soo , Lockley Martin G. , Larsson Hans C.E. , Holtz Thomas R. , Farlow James O. , Pittman Michael
Published: October 2024

Body fossils set limits on feasible reconstructions of functional capacity and behavior in theropod dinosaurs, but do not document in-life behaviors. In contrast, trace fossils such as footprints preserve in-life behaviors that can potentially test and enhance existing reconstructions. Here, we demonstrate how theropod trackways can be used as indirect evidence of pre-avian aerial behavior, expanding the approaches available to study vertebrate flight origins. This involved exploring the behavioral implications of a two-toed Cretaceous-aged theropod trackway produced by a small, bird-like microraptorine moving at high speed. Applying first principle running biomechanics, we were able to conclude that the trackway is atypical, indirectly evidencing pre-avian aerial behavior. This trackway documents the evidence of wing-assisted aerodynamic force production during locomotion, supporting a broader distribution of this behavior than currently known. These findings support previously proposed aerial behavior in early bird-like theropods, showing how trackways will help to deepen our understanding of theropod flight origins.
Exploring dog-parent guilt: Do human attachment styles play a role?
Authors: Dye Heather
Published: October 2024

Given the prevalence of pet ownership in homes, understanding and acknowledging the role of human-animal relationships within the family is critical. Many pet owners identify as “pet parents” and actively pamper their pets with human-grade food, have birthday parties, schedule play dates, and dress them up in clothes and accessories. More homes in the United States have pets than children. In this study, a sample of 332 dog owners from the United States, stratified according to age and sex, completed an online survey. This study used several instruments such as the CENSHARE pet attachment scale, guilt about dog-parenting scale, work-dog conflict scale, making-up behavior scale, and revised adult attachment scale. Correlation analyses and linear regressions were conducted to determine the nature of the relationships between the variables. As predicted, this study found that stronger pet attachment increased dog-parent guilt, work-dog conflict, and make-up behaviors. Moreover, those with an anxious attachment style were more likely to experience dog-parent guilt, also known as disenfranchised guilt. This parental type guilt is when parents feel that work or life demands interfere with their ability to fulfill their role as parents. Pet-parent guilt was similar to that found in parents with human children. Correlation analysis revealed no relationships of pet attachment with any demographic variables, which included sex, age, race, relationship status, household income, and education and parental status. These findings were consistent with a previous study revealing that pet parents who had a strong attachment to their pets experienced dog-parent guilt and work-dog conflict. In addition, this was the first study to examine dog-parent guilt, make-up behaviors, and human attachment styles. Perhaps utilizing a multi-system approach involving educators, mental health professionals, veterinarian professionals, advocates, and organizations can help pet parents feel validated and supported regarding their feelings of guilt. Building a support network for pet parents to connect with others who share similar experiences can validate their feelings and help those who feel isolated.
Gauss–Bonnet AdS planar and spherical black hole thermodynamics and holography
Authors: Paul Souvik , Gangopadhyay Sunandan , Saha Ashis
Published: October 2024

In this work, we extend the study in Bilic and Fabris (2022 J. High Energy Phys. JHEP11(2022)013) incorporating the AdS/CFT duality to establish a relationship between the local temperatures (Tolman temperatures) of a large (AdS) spherical and a (AdS) planar Schwarzschild black hole near the AdS boundary considering Gauss–Bonnet (GB) curvature correction in the gravitational action. We have shown that the higher curvature corrections appear in the local temperature relationship due to the inclusion of GB term in the bulk. By transforming the metric into Fefferman–Graham form, we have calculated the energy density of the conformal fluid at the boundary. The obtained result contains finite coupling corrections which are holographically induced by the GB curvature correction in the bulk theory. Following the well known approach of fluid/gravity duality, the energy density of the conformal fluid at the boundary is then compared with the black body radiation energy density. This comparison shows that the energy density is proportional to the temperature of the conformal fluid. The temperature of the conformal fluid is then shown to be related to the Tolman temperature of the black hole which then eventually helps us to establish both the Hawking temperature and Tolman temperature relationship between large spherically symmetric and planar Schwarzschild black holes in GB gravity near the AdS boundary.
Anisotropic hypocycloid inspired 3-bit digital coding metasurface for radar cross section reduction
Authors: Wang Chao , Wang Wen-Song , Li Yan-Ling , an Lei , Niu Fei , Wang Ru-Zhi , Zhang Sheng-Jun , Liu Jia-Qi
Published: October 2024

Recently, researchers have realized various exotic electromagnetic control devices using the coded metasurfaces, sparking a broad investigation into the phase or amplitude-based encoding method, as well as their combination, in the field of metasurface design. In this paper, to evaluate the influence of random mutual coupling between the adjacent element on the scattering performance of metasurface, and also to minimize the backward radar cross section (RCS) of metal plate targets, a novel encoding approach combining the reflection phase and element-form has been proposed. During the implementation process, an anisotropic hypocycloid inspired 3-bit digital coding metasurface was designed. It consists of 9 different element-forms, with each capable of providing 7 phase states. Simulation results demonstrate that the random mutual coupling introduced by the proposed elements does not significantly affect the RCS performance of the metasurface. With a good polarization insensitivity property for both linearly and circularly polarized waves, the designed 3-bit digital coding metasurface can achieve more than 20 dB RCS reduction at 10 GHz, while simultaneously transmitting additional information by encoding the element forms. The good consistency between theoretical simulation and sample testing unequivocally validates the precision of the design, this paper may serve as a useful reference for expanding the design methods of metasurfaces.
Weighted squared envelope nonlinear Gini index and its application to rotating machinery condition monitoring
Authors: Xie Xuyang , Yang Zichun , Zhang Lei , Xie Luotao , Wang Jintao , Chen Guobing
Published: October 2024

Sparsity measures (SMs) are effective tools for rotating machinery condition monitoring. However, under complex operating conditions, existing SMs often exhibit significant fluctuations, making it difficult to accurately detect early faults and monotonically represent the degradation processes. To tackle these challenges, a novel health indicator (HI) named the weighted squared envelope nonlinear Gini index (WSENGI) is proposed in this paper. Firstly, by introducing a nonlinearly increasing weight sequence inspired by the sigmoid function and the quadratic function-based quasi-arithmetic mean (QAM), a novel SM, the nonlinear Gini index (NGI), is developed based on the ratio of different QAMs framework. Building upon this foundation, the WSENGI is further constructed for condition monitoring by incorporating the weighted squared envelope into the NGI. When applied to two bearing run-to-failure datasets, the proposed HI shows improved sensitivity to early fault features and is able to depict the degradation processes monotonically, demonstrating notable advantages in condition monitoring.
Effective Faraday interaction between light and nuclear spins of helium-3 in its ground state: a semiclassical study
Authors: Fadel Matteo , Treutlein Philipp , Sinatra Alice
Published: October 2024

We derive the semiclassical evolution equations for a system consisting of helium-3 atoms in the

2
3

S

metastable state interacting with a light field far-detuned from the

2
3

S
−

2
3

P

transition, in the presence of metastability exchange collisions with ground state helium atoms and a static magnetic field. For two configurations, each corresponding to a particular choice of atom–light detuning in which the contribution of either the metastable level

F
=
1

/

2

or

F
=
3

/

2

is dominant, we derive a simple model of three coupled collective spins from which we can analytically extract an effective coupling constant between the collective nuclear spin and light. In these two configurations, we compare the predictions of our simplified model with the full model.
Mirror-symmetry-induced pseudospin filtering of phonons in graphene nanoribbons
Authors: Chen Xiaobin , Cui Shiyu , Hu Yizhi , Yan Kun
Published: October 2024

Unlike electrons, phonons do not have the charge and spin degrees of freedom. Consequently, it is a big challenge for the control of phonon currents and the design of quantum phonon devices due to the lack of versatile degrees of freedom. In this work, we show that phonon bands of mirror-symmetric materials can be labeled by parities, which can act as a pseudospin of phonons. As a proof-of-concept, we show that perfect pseudospin filtering can be realized using mirror-symmetric graphene-nanoribbon heterojunctions. In addition, we show that the filtering takes place within a remarkably short length scale of just 3 nanometers. Our work reveals an intriguing new facet of phonon behavior and also underscores the immense potential of utilizing phonons as information carriers.
Dynamics of finite width Kernel and prediction fluctuations in mean field neural networks*
Authors: Bordelon Blake , Pehlevan Cengiz
Published: October 2024

We analyze the dynamics of finite width effects in wide but finite feature learning neural networks. Starting from a dynamical mean field theory description of infinite width deep neural network kernel and prediction dynamics, we provide a characterization of the

O

(
1

/

width

)

fluctuations of the dynamical mean field theory order parameters over random initializations of the network weights. Our results, while perturbative in width, unlike prior analyses, are non-perturbative in the strength of feature learning. We find that once the mean field/µP parameterization is adopted, the leading finite size effect on the dynamics is to introduce initialization variance in the predictions and feature kernels of the networks. In the lazy limit of network training, all kernels are random but static in time and the prediction variance has a universal form. However, in the rich, feature learning regime, the fluctuations of the kernels and predictions are dynamically coupled with a variance that can be computed self-consistently. In two layer networks, we show how feature learning can dynamically reduce the variance of the final tangent kernel and final network predictions. We also show how initialization variance can slow down online learning in wide but finite networks. In deeper networks, kernel variance can dramatically accumulate through subsequent layers at large feature learning strengths, but feature learning continues to improve the signal-to-noise ratio of the feature kernels. In discrete time, we demonstrate that large learning rate phenomena such as edge of stability effects can be well captured by infinite width dynamics and that initialization variance can decrease dynamically. For convolutional neural networks trained on CIFAR-10, we empirically find significant corrections to both the bias and variance of network dynamics due to finite width.
What can be learnt with wide convolutional neural networks?*
Authors: Cagnetta Francesco , Favero Alessandro , Wyart Matthieu
Published: October 2024

Understanding how convolutional neural networks (CNNs) can efficiently learn high-dimensional functions remains a fundamental challenge. A popular belief is that these models harness the local and hierarchical structure of natural data such as images. Yet, we lack a quantitative understanding of how such structure affects performance, for example the rate of decay of the generalisation error with the number of training samples. In this paper, we study infinitely wide deep CNNs in the kernel regime. First, we show that the spectrum of the corresponding kernel inherits the hierarchical structure of the network, and we characterise its asymptotics. Then, we use this result together with generalisation bounds to prove that deep CNNs adapt to the spatial scale of the target function. In particular, we find that if the target function depends on low-dimensional subsets of adjacent input variables then the decay of the error is controlled by the effective dimensionality of these subsets. Conversely, if the target function depends on the full set of input variables then the error decay is controlled by the input dimension. We conclude by computing the generalisation error of a deep CNN trained on the output of another deep CNN with randomly initialised parameters. Interestingly, we find that, despite their hierarchical structure, the functions generated by infinitely wide deep CNNs are too rich to be efficiently learnable in high dimensions.
Universality laws for Gaussian mixtures in generalized linear models*
Authors: Dandi Yatin , Stephan Ludovic , Krzakala Florent , Loureiro Bruno , Zdeborová Lenka
Published: October 2024

Let

(

x

i

,

y

i

)

i
=
1
,
…
,
n

denote independent samples from a general mixture distribution

∑

c
∈

C

ρ

c

P

c

x

, and consider the hypothesis class of generalized linear models

y
^

=
F
(

Θ

⊤

x

)

. In this study, we investigate the asymptotic joint statistics of a family of generalized linear estimators

(

Θ

1

,
…
,

Θ

M

)

obtained either from (a) minimizing an empirical risk

R
^

n

(

Θ

;

X

,

y

)

or (b) sampling from the associated Gibbs measure

exp
⁡
(
−
β
n

R
^

n

(

Θ

;

X

,

y

)
)

. Our main contribution is to characterize under which conditions the asymptotic joint statistics of this family depends (in a weak sense) only on the means and covariances of the class conditional features distribution

P

c

x

. In particular, this allows us to prove the universality of different quantities of interest, such as the training and generalization errors, redeeming a recent line of work in high-dimensional statistics working under the Gaussian mixture hypothesis. Finally, we discuss the applications of our results in different machine learning tasks of interest, such as ensembling and uncertainty quantification.
Scaling properties of (2+1) directed polymers in the low-temperature limit
Authors: Dotsenko Victor
Published: October 2024

In terms of the replica method, we consider the low-temperature limit of (2+1) directed polymers in a random potential. The proposed approach allows us to compute the scaling exponent θ of the free energy fluctuations as well as the left tail of its probability distribution function. It is argued that

θ
=
1

/

4

, which is slightly different to the zero-temperature numerical value that is close to 0.241.
Error analysis of a coaxis five-bar parallel mechanism
Authors: Shen Guoxing , Liao Bin
Published: October 2024

With societal advancement, robots are increasingly being deployed in production processes. Currently, high-precision robots predominantly found in the market are delta parallel robots. Common parallel robots, including delta robots, generally suffer from the drawback of having a smaller workspace compared to serial robots. Contrasted with other types of parallel robots, coaxis parallel robots feature a larger workspace, thereby offering greater potential for application. This paper focuses on a coaxis five-bar parallel mechanism as the subject of investigation. Firstly, by employing the perturbation method to model the errors in the parallel mechanism, a mapping relationship between error sources and the errors of the mechanism’s end-effector was derived. Then a sensitivity analysis of each error source was performed statistically, yielding sensitivity metrics. Last, under conditions where the magnitudes of errors are identical, the end-effector error of a coaxis parallel mechanism is notably larger compared to that of a common parallel mechanism. This makes it more essential to conduct precision design on coaxis parallel robots in the future study.
Modeling and simulation study of acoustic response for dual-membrane capacitive MEMS microphone
Authors: Hu Siqi , Hu Haitao , Xue Wei , Kang Dianyu , Xiao Jing
Published: October 2024

As the micro-electro-mechanical systems (MEMS) technology matures, MEMS sensors have found widespread applications in mechatronics, robotics, and voice control. The high stability, high integration, and radio frequency interference resistance of MEMS microphones have rapidly led to their adoption in these domains, displacing electret condenser microphones.This article focuses on modeling and analyzing dual-membrane capacitive MEMS microphone, utilizing an lumped equivalent circuit model to calculate the microphone’s acoustic frequency response. Furthermore, the article employs the finite element method (FEM) to conduct a detailed analysis of the resonant frequency of the membrane, as well as to explore the effects of changes in the volume of the front and back chamber on the packaging performance of MEMS microphones. Finally, physical tests were conducted, and the simulation results of the two models showed considerable consistency with the curves obtained from the physical tests, verifying the accuracy of the models.
Improved traffic sign detection algorithm for lightweight YOLOv8
Authors: Qin Hualu , Yin Zhe
Published: October 2024

In robotics and automated control systems, effective utilization of resources and real-time performance are critical to system performance. For traffic sign detection existing Convolutional Neural Networks (CNN), You Only Look Once (YOLO), etc, the former performs end-to-end detection, more senior feature representations can be learned, and performs better in complex scenarios, but it needs a lot of labeled data for training; the latter performs better in terms of accuracy and speed, and is able to quickly detect traffic signs and give location information, but requires higher computational resources. To overcome the problems of poor real-time transportation sign detection and mini-goals, a lightweight traffic sign proposed algorithm for the detection of devices based on YOLOv8. In this study, on the YOLOv8n model, instead of the normal convolution in BottleNeck, we propose to replace the Faster Implementation of CSP Bottleneck with 2 convolutions (C2f) structure in the backbone network with a partial convolution (PConv), resulting in a structure (CSPPC); Introduction of Cross-Scale Feature Fusion Module (CCFM) proposed by Real-Time Detection, Embedding, and Tracking (RT-DETR) modeling; Use Weighted Interpolation of Sequential Evidence for Intersection over Union (Wise-IoU) loss function. Modified method was trained on the road sign dataset and the number of parameters was reduced by 49.83% compared to the initial model, Mean Average Precision (mAP) increase of 3.92%, and the decrease in floating-point operations is 34.57%. Results show that YOLOv8n model meets the requirements of high detection accuracy and lightweight modeling with great advantages in robotics and automated control systems to accelerate the recognition and decision-making process and improve the response speed of the system.
Effect of friction layer thickness on energy conversion efficiency of traveling wave rotary ultrasonic motor
Authors: Wei Deqiang , Wan Aohui , Guo Lianghong , Nie Rui , Chen Hucheng
Published: October 2024

Due to its compact size and resistance to electromagnetic interference. Applications for traveling wave rotary ultrasonic motors (TRUM) include robotic joint drives and aerospace.The motor’s energy conversion efficiency is impacted by the characteristics of the friction layer, yet the underlying mechanism influencing the efficiency remains unreported. Using the previously created finite element model, the mechanism via which the amount of thickness within the friction layer influences the motor output characteristics is examined.Analysis is done on the variations in motor loss, energy conversion efficiency, and input-output characteristics. The computation results show that when the friction layer is less than 0.4 mm, the machine’s output speed increases as the friction layer’s thickness decreases.The results of the calculation indicate that when the friction layer thickness is between 0.05 and 0.4 mm, the motor’s output torque and speed would drop. The findings indicate that the output torque and motor torque decrease as the friction layer thickness increases when it is between 0.05 and 0.4 mm. Both the viscoelastic losses and the motor’s energy conversion efficiency rise.Research shows that the friction layer thickness has a huge impact on the motor and cannot be ignored, providing a reference for the application of motors in industries such as robot joints.
Flow field analysis of newtonian fluid flow induced by planetary and radial motion of drill string
Authors: Wang Zhigang , Zhang Liye , Wang Qi , Xi Zheng , An Di , Zheng Jun , Guo Yongxuan
Published: October 2024

At present, in the process of oil drilling, the drill string is an essential downhole drilling tool. It is immersed in the hole filled with drilling fluid for a long time, and it is driven by the rotation of the rotary table to drill down. In this process, the drill string will not only rotate around its axis but also may rotate around the axis of the hole and produce radial motion. It is important to study the flow law of Newtonian fluid flow induced by drill string movement, which can effectively reduce drilling accidents caused by drill string vortex and buckling, thus reducing economic losses. After research and analysis, the finite volume method, which has good applicability and obvious advantages, is used to discretize the established mathematical model, and the mathematical equation after discretization is obtained. By using MATLAB software, the flow field of Newtonian fluid induced by drill string rotation motion is analyzed, the axial velocity distribution diagram and tangential velocity distribution diagram are obtained, and the velocity flow diagram under different eccentricity conditions is drawn. It is found that secondary flow occurs only when the eccentricity reaches a certain distance requirement.
Numerical simulation of complex slope dike overtopping wave flow under isolated wave action based on OpenFOAM
Authors: Hou Yadong , Ye Junwei , Wang Shiwen
Published: October 2024

In recent years, a significant number of compound slope dikes have been developed, but research on the over-wave flow of their viewing platforms remains relatively sparse. In this paper, isolated waves are selected to simulate storm surges. Numerical flumes are constructed based on OpenFOAM to explore the thickness and flow velocity of overtopping wave flow impacts and the thickness and flow velocity of backwash flow on viewing platforms on a compound slope dike with three different foreslope gradients. The study finds that both the impact thickness and return thickness of the cross-wave flow show a tendency to decay along the course, and the smaller the relative wave height is, the slower the impact thickness decays along the course, and the faster the return thickness decays along the course.
Study on flow regime characteristics in 3×3 rod bundle channels based on wire mesh sensor
Authors: Long Pengchen , Shi Haopeng , Zhao Meng , Cheng Yixuan
Published: October 2024

The characteristics and evolution of two-phase flow are of critical importance to the safety of pressurized water reactors. Based on the double-layer wire mesh sensors in this paper, the air-water two-phase flow experiment of the 3×3 rod bundle channels is carried out at room temperature and pressure. The results show that the critical bubble diameter range for the reversal of lateral lift direction is 4 to 5.8 mm. In addition, the time-averaged void fraction for bubbly flow reveals a wall peak distribution at lower superficial gas velocities and shifts to a core peak as these velocities increase. For cap flow, the cross-distribution of cap bubbles within adjacent subchannels triggers large-scale mixing of the liquid phase between adjacent subchannels. For slug flow, large-sized bubbles develop along the axis and cross subchannel gaps to aggregate into slug-shaped bubbles, with a more pronounced distribution of the central peak of void fraction. The drift-flux models are evaluated against the experimental data, and the Ozaki model demonstrates higher precision in estimating void fraction, exhibiting a deviation of 9.8% on average.
Study on flood level forecasting of tidal reach in Puyang River basin
Authors: Zhen Yiwei , Guo Ming , Li Penghui , Chen Jianzheng , Liu Yucheng
Published: October 2024

The downstream section of the Puyang River is a tidal river reach subject to both upstream floods and downstream tides. This combined impact results in an unstable relationship between water level and discharge at the forecast station, making flood level forecasting challenging. This paper took the Linpu station on the Puyang River in Zhejiang Province as the research object. Based on the historical flood data, the cause of high water levels at Linpu station was analyzed. The flood levels at Linpu station were decomposed into flood increments and basic tidal levels. Using the multiple regression method, the prediction formula for upstream flood-induced water level increments was obtained. A flood level forecasting method based on the flood increment was developed. The result of the scheme accuracy evaluation indicates that this method has good forecasting performance. The flood level forecasting method for the tidal channel proposed in this paper has a simple structure and high accuracy, which provides a scientific basis for the prevention and control of flood and drought hazards and the decision-making of project scheduling in the tidal river.
Research on the hydraulic response characteristics during the water conveyance process of water diversion projects
Authors: Hu Hui , Liu Guoping , Tao Lei
Published: October 2024

During the initial trial period, the Hanjiang-to-Weihe River Valley Water Diversion Project (HWRVWD) sourced water from the Sanhekou water conservancy junction. It then transferred water through the Qinling water conveyance tunnel and distributed it at the Huangchigou water distribution hub, ultimately transporting it to the Guanzhong area. The hydraulic simulation and real-time control of the water conveyance system play a crucial role in ensuring the safe and efficient operation of this engineering project. To maintain water transfer safety and reasonable scheduling during the water supply process, the hydraulic characteristics of the transient process were calculated and analyzed in this paper. The one-dimension (1D) hydrodynamic mathematical model and advection-dispersion model were established to calculate the hydraulic factors of the 81.78 km Qinling water conveyance tunnel and the Huangchigou water distribution hub within the HWRVWD. Validation results showed that the root mean squared error tended toward zero and the coefficient of determination exceeded 0.97 between the measured values and the simulated values. The opening of gates and upstream inflow directly affected water level variations and storage. Smaller gate openings led to increased water level amplitudes before the gate and faster reaching of maximum water levels, but it also led to opposite trends in flow rates behind the gate compared to upstream water levels. The impact of incoming water flow rates on flow variations at different channel sections was significant. The time for water heads to reach each section and the rate of flow variation positively correlated with incoming water flow rates. Gradual increases in upstream inflow resulted in progressively larger water level amplitudes both before and behind the gate, with an increased maximum value, but more water might be discarded. When the water demand changes, the primary focus is on controlling the upstream inflow, with gate opening adjustments as a secondary measure, to achieve the goal of minimizing or eliminating water wastage.
Simulation analysis and hydrodynamic performance optimization of small MHD thruster based on improved I-bridge structure
Authors: Zhang Xinyu , Zhao Junyi , Chen Gong , Wu Boqian , Du Yibo
Published: October 2024

Magnetic hydrodynamic drive (MHD) generates thrust by the coupling interaction of three fields: flow field-electric field-magnetic field. Because this propulsion method has no propeller or mechanical structure, it has the advantages of quiet, simple structure, easy operation, flexible layout, and difficult to detect. This is the current research hot spot. In order to meet the needs of miniaturized silent propulsion, this paper selects a linear internal magnetic thruster for research and analysis and improves the design of an I-shaped magnetic bridge structure. Firstly, the thrust and efficiency of the thruster under ideal conditions are calculated, and the thruster model is established. The conclusion is that the I-shaped magnetic bridge can increase the magnetic field intensity of the channel and significantly improve the MHD propulsion efficiency. At the same time, it is found that MHD thruster can reduce noise during operation, but the current required for propulsion is large, and seawater electrolysis will occur, which has a certain impact on the environment. Finally, the problems of small direct drive MHD propulsion are analyzed, and the future development direction of MHD propulsion is prospected.
Numerical simulation study of acoustic source characteristics of liquid level monitor based on infrasound waves
Authors: Wu Xinyuan , Xu Jiaoyun , Li Ning
Published: October 2024

To investigate the sound source characteristics of infrasound waves generated during the operation of the gas explosion liquid level monitoring instrument, with a focus on the aerodynamic noise produced by the monitoring device, a mixed numerical method was used to simulate and study the impact of different nozzle diameters, gas explosion pressures, and casing pressures on the instrument’s infrasound frequency range. The results indicate that gas explosion pressure, casing pressure, and nozzle diameter primarily affect the spectral characteristics within the 10 Hz to 20 Hz range. As the gas explosion pressure and nozzle diameter increase, the sound pressure level in the internal sound field also increases, and the peak frequency shifts higher. Conversely, with an increase in casing pressure, the sound pressure level in the internal sound field decreases, and the peak frequency shifts lower. The research findings can provide a theoretical basis for the development of the instrument.
Variable target water level control method in front of sluice in flood storage area based on storage balance model
Authors: Xu Xiaoyou
Published: October 2024

To prevent the increase in flood disaster frequency, scale, and impact degree, a flood control engineering system with flood storage and detention areas, embankments, and reservoirs as the main body has been formed. Flood storage area is the key to the flood control engineering system, and its water level control performance is directly related to the success of flood control. According to the actual situation, the flood evolution simulation model in the flood storage area is constructed to obtain the evolution information of any unit of flood in the flood storage area. The dynamic control judgment coefficient of the water level is calculated, and the dynamic control program of the variable target water level in front of the sluice is formulated. Water level control can be realized by executing the established procedures. The above experimental data show that the proposed method can effectively control the water level in the flood storage area within the range of 26.03m ∼ 29.12m, and the minimum value of the corresponding risk rate is 3%, which fully proves that the proposed method has better dynamic control effect on the variable target water level in front of the sluice.
Great lakes basin model based on physical flow and Data-Driven
Authors: Huang Yijing , Yang Shijia , Liu Anqi
Published: October 2024

As a group of freshwater lakes, the Great Lakes span the United States and Canada and have a great impact on the economies and environments of the regions. To meet the needs of various stakeholders, it is significant to regulate the flow through the control mechanism to achieve the optimal water level balance. Combined Physical Process and Data-Driven, this paper established a dynamic model of the Great Lakes based on the lake dependence relationship and complex climate factors. After judging the optimal water level by combining the needs of all stakeholders, the hydrodynamic model is run to verify and predict the water level, and the flow control algorithm is obtained. The results show that the prediction of optimal water level has a high accuracy rate. After the flow control, the error between the predicted and optimal water levels is greatly reduced.
Research on the response of underwater explosion side structure based on RKPM method
Authors: Zhao Chuanqi , Chen Xin , Cui Jie
Published: October 2024

Based on smoothed particle hydrodynamics and reproducing kernel particle method, this paper establishes a fluid-structure interaction three-dimensional calculation model for the dynamic response of complex structures to underwater explosion shockwave, verifies the effectiveness, accuracy and progressiveness of SPH-RKPM coupling calculation, and establishes a control condition with detonation distance as a variable to determine the dynamic response characteristics of ship side under shockwave loads generated by underwater explosion at different detonation distances.
Inverse algorithm for boundary heat flux density based on the NARX neural network
Authors: Deng Liang , Li Haidong , Wang Youtong , Chen Changxu , Pan Zhenhai
Published: October 2024

The inverse heat transfer problem is vital for scientific research and engineering applications. This paper introduces a method using the Nonlinear Autoregressive with Exogenous Inputs (NARX) neural network to identify heat boundary conditions in nonlinear transient heat transfer processes in real time. This method has two notable advantages: (1) It relies solely on surface temperature time series to obtain inversion results; (2) Even in the absence of knowledge regarding the system’s state equations, it can estimate heat flux density. The NARX neural network is trained by using Bayesian regularization with surface temperature and heat flux data. (3) As per the inversion results, the NARX neural network’s accuracy in predicting the boundary heat flux density (BHFD) increases as the temperature measurement points approach the heat flux boundary. This neural network calculates the current heat flux density by incorporating both present and past surface temperature measurements as inputs. Through numerical simulation experiments, the efficacy of the NARX method is confirmed, showcasing its exceptional accuracy, robustness against noise, and broad suitability.
Separate prediction of underwater noise from drain pipes base on Vibration-acoustic coupling method
Authors: Qi Qiongfang , Peng Xianyong , Jiang Shiliang , Li Guangming
Published: October 2024

Since drain pipes on ships radiate underwater noise when in use, the components and radiation characteristics of flow noise and flow-induced noise from drain pipes on ships are explored, and the relationship between peak spectral values and wet mode frequencies is analyzed. The numerical calculation models of the flow field and structure for drain pipes are created respectively to obtain pulsating pressures in the flow field and structural mode values. Then, the flow noise and flow-induced noise are separately measured in an acoustic model developed for drain pipes upon the mapping of wall fluid meshes, structural meshes and acoustic meshes. A vibration-acoustic coupling model with the radiated sound field nephogram is presented based on the wall pulsating pressure and structural mode values. The numerical calculation indicated a significantly louder flow noise from drain pipes than the negligible flow-induced noise. The resulting wet mode of drain pipes solved by the Boundary Element Method (BEM) reflects the similarity between the peak spectral value and the wet mode frequency of flow-induced noise, marking that the fluid pulsating pressure excites noise.
Numerical simulation and analysis of motion responses and added resistance of a KRISO container ship in regular waves
Authors: Yang Xinglin , Wu Shaohui , Du Xin
Published: October 2024

In order to explore the influence of vessel speed on seakeeping characteristics and provide valuable insights for ship performance evaluation, the accurate prediction of ship motion and resistance in wave conditions is essential. In this study, the variations in ship motion and resistance with respect to ship speed are analyzed during navigation in regular waves. The results suggest that the added resistance coefficient of the KCS demonstrates an initial rise, succeeded by a subsequent decline, with the expansion of wavelength. Moreover, the peak non-dimensional resistance coefficient, observed at different ship speeds, demonstrates an upward trend with the augmentation of ship velocity. This research methodology provides a valuable tool for numerically predicting the hydrodynamic performance of vessels in regular wave conditions.
Study on seawall deformation analysis based on seawall inner foundation pit excavation
Authors: Zhao Yun , Liao Tingting , Liu Xingle , Jin Qianqian
Published: October 2024

The purpose of this study is to assess the potential effects of excavation activities on the structural deformation of the Shitang seawall in Shandong Province during the treatment of an informal landfill in the Yantou Industrial Area, Jiaojiang. By using nonlinear elastic analysis and Mohr-Coulomb elastic-plastic model, combined with MIDAS GTS NX software, the effects of construction on the seawall are analyzed in detail. The monitoring data show that the deformation caused by the foundation pit construction is in a safe range and will not pose a threat to the safety of the seawall. The corresponding construction period suggestions are put forward to ensure the safety of the project and provide references for similar projects to enhance the safety and reliability of the design.
Aerodynamic design of two-stage centrifugal compressor for vehicle hydrogen fuel cell
Authors: Wang Zhongjun , Zhang Ke
Published: October 2024

The on-board hydrogen fuel cell is a power generation device that converts the chemical energy of hydrogen and oxygen directly into electrical energy. The centrifugal compressor mainly provides oxygen for the cathode of the fuel cell system. With the rapid development of the hydrogen fuel cell industry, the key components of the air compressor field are also developing rapidly. In the technical route, most companies launched two-stage compression centrifugal air compressors in response to the increasing power of the product development trend. The newly developed hydrogen fuel cell system power has reached above 120kW to meet the needs of heavy trucks and other applications. Both the flow rate and pressure ratio of the air compressor are required to increase accordingly. Based on the reduction of parasitic power, the optimal efficiency at the working point of the two-stage centrifugal air compressor is taken as the design goal, from one-dimensional aerodynamic calculation to two-dimensional flow channel design. Finally, the feasibility and accuracy of the aerodynamic design are verified based on key parameters such as pressure ratio, flow rate, and efficiency of the final stage through CFD flow field simulation and test data comparison. The results show that the flow rate is consistent with the calculated flow field, and the maximum error of pressure ratio and efficiency is less than 2%, which meets the target requirements. The research results can provide a research and development basis for designing high-performance centrifugal air compressors for fuel cell vehicles.
Design of experimental section of a water tunnel for simulation of heat dissipation condition of seawater-activated battery
Authors: Tang Qingyan , Dou Zhaoliang , Du Yue , Chen Qianghua , Liu Fengbin
Published: October 2024

A water tunnel is a crucial experimental apparatus in hydrodynamic research, as the traditional water tunnel has drawbacks such as a small cross-sectional area of the test section and higher costs, which makes it difficult to meet the requirements of a water tunnel for simulating the heat dissipation conditions of the seawater-activated battery. This paper proposes a water tunnel specifically designed for simulating the heat dissipation conditions of seawater-activated batteries, and the water tunnel consists of an external cooling water circulation system and an internal electrolyte circulation system. The experimental section’s design determines the water tunnel’s size and key technical indexes. The temperature distribution contour maps of the experimental section were obtained using Ansys Fluent software simulation. The cooling effect was analyzed, and a cooling water flow rate of 10 m/s was selected. Pressure and velocity contour maps were obtained by simulating the experimental section of the water tunnel. The results show that when the cooling water velocity is 10 m/s, the pressure drop of the experimental section is approximately 1.76 atmospheres. The flow field is uniform and stable, and the heat dissipation power can reach 45.5 kW, meeting the technical requirements.
Ship model self-propulsion instrument development and test verification
Authors: Wu Yongshun , Ma Qiang , Xu Wenjun , Xia Wenjing , Yang Sujun
Published: October 2024

Aimed at the characteristics of high precision requirements and large environmental changes of the thrust and torque coupling test in the self-propulsion test of the ship model, the paper carries out the design of the instrument of the ship model test, the calculation of structural strength, the design of anti-jamming of the thrust and torque coupling, and the selection and realization of thrust and torque module. Based on the above, the instrument was calibrated with sensitivity coefficient, high and low temperature, and dynamic stability tests. Besides this, a self-propulsion test at the design speed point of a ship was carried out to verify the accuracy and environmental adaptability. From the static calibration result, the coefficient of determination is 1.0. The max zero drift of thrust and torque is 0.11% FS and 0.05% FS respectively from the low-high temperature test, and the max zero drift of torque under different revolutions is 0.23% FS from the dynamic test. In addition to the above, the max deviation between Maric-SP01 and R31 of thrust and torque is less than 0.78% and 0.65% respectively from the ship model self-propulsion test. So, in one word, the instrument has good reliability and accuracy and can meet the requirements of the ship model self-propulsion test.
Analysis of the response of wind-induced vibrations on flexible photovoltaic mounts
Authors: Wu Sichuan , Wu Haikian , Lou Yibing
Published: October 2024

This article investigates a flexible photovoltaic bracket’s response to wind vibration. A finite element model is established using SAP2000 software for time course analysis. Representative units and nodes were selected to analyze internal force response, displacement response, and acceleration response. The prestress and span change rule of the flexible photovoltaic bracket are also explored, and quantitative research is conducted on the size of prestress and span size. The magnitude of the prestress affects a structure’s responsiveness to wind vibration. As prestress grows, so do deflection and acceleration, and the rate at which axial force is increasing also increases. Conversely, when prestress increases, the rate of deflection reduction falls. Consequently, considering the prestress size, it is advised that 50-kN prestressing be used for the support and wind cables. As the span rises, so do the mid-span span and the axial force of the wind cables, while acceleration also increases. The rate of mid-span deflection increases gradually with the flexible PV mount span, but the rate of axial force increase decreases. It is recommended to limit the span to below 50 m.