Model Experiments Research Articles

Advanced prediction method of biological tissue mechanical response based on hybrid prediction model.

The mechanical response of biological tissue is an important basis for evaluating its state during the surgical operation. Accurate prediction of mechanical response is helpful to improve the precision of surgical operation. In this paper, An advanced prediction method based on hybrid prediction model is proposed and used to predict the mechanical response of soft tissue. Firstly, the simulation model of soft tissue indentation experiment was established to obtain the mechanical response under continuous loading condition. The mechanical response of kindy tissue under discontinuous loading was obtained by the actual indentation experiment. Secondly, the mechanical response is predicted and the influence of loading parameters on the prediction accuracy is analyzed. The mechanical response under continuous loading was obtained by simulation, and the mechanical response under non-continuous loading was obtained by indentation experiment. The proposed advanced prediction method is verified by the obtained mechanical responses. The results show that the proposed method can predict the mechanical response of soft tissue well. The proposed prediction algorithm is helpful to predict the mechanical response in advance and avoid the potential tissue damage caused by surgical operation.

A model experiment to study the metal pad roll instability under ambient conditions

We present a new model experiment to study the metal pad roll (MPR) instability, which is a limiting factor for the safe operation of aluminum reduction cells. The idea of our experiment is to replace the horizontal electrical currents in the aluminum layer, which are caused by displacements of the cryolite–aluminum interface in industrial reduction cells, with a synthetic current that is supplied through the side walls of the experimental cell. In this way, only one liquid layer of an electrically conducting fluid is required for modeling the MPR instability, allowing the experiment to operate under ambient conditions using the room-temperature liquid alloy GaInSn as the current-bearing fluid. We demonstrate that the experimental model allows self-amplifying MPR waves to be destabilized and maintained in a reproducible way. The setup is equipped with an acoustic measurement technique that facilitates precise submillimeter measurements of liquid metal surface elevations, which makes it possible to determine several key quantities such as MPR growth rates, stability onsets, saturation amplitudes, or viscous and magnetic damping rates. As the MPR destabilizing Lorentz force synthesized in the experiment can be calibrated to the Lorentz forces appearing in real two-layer cells, the proposed model experiment is intended to establish a novel framework for experimental benchmarking.

Aeroacoustic experiment and broadband noise model of contra-rotating ducted fan under different rotating speeds

Aeroacoustic experiment and broadband noise model of contra-rotating ducted fan under different rotating speeds

Model experiment and numerical simulation study on the instability of shield tunnel face in upper-clay and lower-sand composite strata

Model experiment and numerical simulation study on the instability of shield tunnel face in upper-clay and lower-sand composite strata

High-precision model predictive control and experiment of an unmanned surface vehicle with Gaussian process-based error model

Model Predictive Control (MPC) is commonly employed for trajectory tracking in control systems. However, Unmanned Surface Vehicle (USV) systems frequently encounter disturbances and model inaccuracies, resulting in mismatches between predicted and actual behaviors. This paper proposes a Gaussian Process Model Predictive Control (GP-MPC) framework to address the challenges of trajectory tracking in USVs. The MPC framework comprises a nominal model based on kinematic analysis and a Gaussian process error model. The latter compensates for system inaccuracies using sampled data. Simulations and real-world tests are conducted to compare GP-MPC with conventional MPC. The results demonstrate that GP-MPC outperforms the conventional MPC in accurately guiding the USV along the desired trajectory, effectively mitigating environmental disturbances and measurement uncertainties, and enhancing the accuracy and stability of trajectory tracking.

Fractal study on blasting damage under decoupled charge structure

To investigate damage range and damage degree of PMMA under different decoupling charge coefficients ( K ) after blasting, a reasonable range of decoupling coefficient was theoretically determined. Experimental images after blasting were obtained through two-dimensional (2D) model experiment. Algorithms for computing damage variables and fractal dimensions of cracks in different zones were developed in MATLAB software, and the relationship between fractal dimension and blasting damage was established. The results indicated that as the decoupling coefficient increased, the length of the longest primary crack and the total length of cracks decreased gradually. Damage variable ( ω ) of the decoupled charge blasting decayed exponentially with increasing distance, ultimately approaching zero. Meanwhile, the attenuation rate increased with increasing decoupling coefficient. The relative sizes of fractal dimensions based on the box-counting dimension algorithm correlated with the macroscopic damage variables. Fractal dimensions in the blasting zones I, II, and III decreased sequentially as the decoupling coefficient increased, resulting in an overall reduction in overall fractal dimension. A prediction model for blasting damage in PMMA material under model experiment conditions was established. The calculated blasting damage degree based on fractal dimension can be used to quantitatively evaluate the spatial distribution characteristics of blasting-induced cracks, which provides a new approach to study the evolution patterns of blasting damage of rocks.

Machine learning operations landscape: platforms and tools

As the field of machine learning advances, managing and monitoring intelligent models in production, also known as machine learning operations (MLOps), has become essential. Organizations are increasingly adopting artificial intelligence as a strategic tool, thus increasing the need for reliable, and scalable MLOps platforms. Consequently, every aspect of the machine learning life cycle, from workflow orchestration to performance monitoring, presents both challenges and opportunities that require sophisticated, flexible, and scalable technological solutions. This research addresses this demand by providing a comprehensive assessment framework of MLOps platforms highlighting the key features necessary for a robust MLOps solution. The paper examines 16 MLOps tools widely used, which revolve around capabilities within AI infrastructure management, including but not limited to experiment tracking, model deployment, and model inference. Our three-step evaluation framework starts with a feature analysis of the MLOps platforms, then GitHub stars growth assessment for adoption and prominence, and finally, a weighted scoring method to single out the most influential platforms. From this process, we derive valuable insights into the essential components of effective MLOps systems and provide a decision-making flowchart that simplifies platform selection. This framework provides hands-on guidance for organizations looking to initiate or enhance their MLOps strategies, whether they require an end-end solutions or specialized tools.

Study on the Spatial Distribution Patterns and Influencing Factors of Soil Organic Carbon Components in Ecological Vegetative Slope Areas

Understanding the spatial distribution patterns of soil organic carbon components in Ecological Vegetative Slopes (EVS) is crucial for optimizing restoration strategies, enhancing soil carbon sequestration capacity, and scientifically evaluating rehabilitation effectiveness. It is an important pathway for promoting sustainable development. This study investigated the effects of slope gradient, slope position, vegetation type, and cement content on the spatial distribution characteristics of soil total organic carbon (TOC) and its components (readily oxidizable organic carbon (ROC) and dissolved organic carbon (DOC)) through slope model experiments and laboratory analyses. The key findings revealed that (1) TOC, ROC, and DOC concentrations decreased with increasing slope gradient and upper slope positions, with steeper slopes amplifying positional effects and exhibiting surface-layer accumulation characteristics. (2) The highest TOC, ROC, and DOC content was achieved in the mixed planting slope with Bermudagrass and Magnolia under a substrate thickness of 3 cm and 3% cement content. Lastly, (3) soil pH increased with the slope gradient and upper positions, showing systematic variations across vegetation types and cement contents. Comparative analysis demonstrated that optimizing vegetation composition and cement dosage effectively enhanced SOC accumulation, while slope gradient and position dominated the spatial heterogeneity of carbon distribution. These results provide theoretical and practical guidance for the precision management of slope ecological restoration. These findings provide robust data support for the ecological sustainability of engineering slope restoration and the enhancement of soil carbon storage.

Experimental and numerical investigations of scours around a rectangular pile cap using a horseshoe-shaped collar

ABSTRACT Local scours around the bridge pier is a common phenomenon in the mobile riverbed, leading to a substantial risk of bridge failures. In this study, the primary objective is to present a protective collar of pile foundations on the basis of flow structure and riverbed erosion. For this purpose, model experiment cooperating with numerical simulations under sandy water conditions was applied to investigate the changes in scour patterns around the rectangular pile cap, and the influence of flow velocity and riverbed height on the scour area and depth was analyzed under conditions without protective measures. On this basis, a horseshoe-shaped collar defined by the elliptical equation was proposed to mitigate the scour on the riverbed. The results show that the scour patterns calculated by computational fluid dynamics are similar to those with experimental methods, the maximum relative deviation of the scour area and depth are 9.16 and 23.94%, respectively. The simulation method can be applied to evaluate the rationality of anti-scouring collar designs. The comparison of topography indicates that scour around the foundation is effectively mitigated with a protective collar; the maximum scour area decreased by 64.85–85.52% for different working conditions. The scour depth was significantly reduced, with a minimum reduction of 66.67%.

Beyond the surface: understanding psychiatric disorders in individuals with spinal cord injury- a narrative exploration.

Spinal Cord Injury (SCI) presents a life-threatening condition that compromises the spinal cord's integrity. Among the complications affecting SCI patients are psychiatric disorders, whose causal mechanisms remain elusive. These disorders are often attributed to multifactorial aspects, encompassing physiological, neurobiological, psychological, and social factors. In the context of SCI patients, we are interested in identifying the specific factors that contribute to the development of psychiatric disorders in this population, emphasizing the critical need for prevention strategies and comprehensive therapeutic management, ultimately aiming to improve the affected patients' quality of life. The process of searching and selecting information was performed between August and December of 2023, utilizing PubMed, ResearchGate, and NCBI as the requisite databases for this review. To ensure precise information retrieval, keywords were strategically employed, focusing on publications spanning from 1985 to the present. MeSH terms, including spinal cord injury, acute spinal cord injury, psychiatric disorders, neuropsychiatry, cognitive impairment, and chronic pain, were applied. A total of 127 articles were identified through electronic searches, and 55 of these were chosen for inclusion in this review. The consulted studies encompassed various types, such as meta-analyses, systematic reviews, animal model experiments, and others. Various factors contributing to the onset of psychiatric disorders in patients with SCI were proposed, all grounded in evidence: neurobiological pathology; cognitive impairment; the impact of systemic diseases on psychological well-being; and, lastly, the correlation between chronic pain and diminished daily functionality, experiences widely encountered by SCI patients. The diagnosis of psychiatric disorders remains largely clinical and syndromic, with unclear causal mechanisms. Understanding psychiatric symptoms in SCI patients requires further investigation. Key contributing factors include neurobiological pathology linked to SCI, cognitive impairment, systemic and organ-specific diseases, and chronic pain associated with reduced functionality. We emphasize the importance of therapeutic and rehabilitative measures that address both physical and psychological health to improve overall quality of life.

Cyano-functionalized polyethylenes from ethylene/acrylamide copolymerization

Synthesizing functionalized polyethylenes via ethylene coordination copolymerization with fundamental low-cost vinyl polar monomers provides a very attractive approach. However, it is also very challenging as the functional group (FG) to be introduced onto the polyolefin chain is directly derived from the corresponding vinyl polar monomers (CH2 = CH-FG), which often cause catalyst poisoning due to the FG coordination to active metal center and β-X elimination during catalysis, etc. It is especially true for the synthesis of cyano-functionalized polyethylenes (PEs) via ethylene/acrylonitrile copolymerization, which can only rely on Pd catalysis with low activity. Here we present an approach utilizing binuclear Ni catalysis for ethylene/acrylamide copolymerization and the synthesis of cyano-functionalized PEs (>99%) with great activity up to 4.1 × 106 g/(mol cat·h). Extensive polymer characterizations (NMR, GPC, model experiments, etc) confirm significant chain transfer and the conversion of amide to nitrile during catalysis. Mechanistic investigations, including comprehensive control experiments, deuterium labeling and computational studies, support an isomerization-mediated chain transfer polymerization (ICTP) mechanistic pathway, which include tandem acrylamide enchainment, amido group conversion into CN group, and active catalyst regeneration by Et2AlCl. Catalyst poisoning could be largely circumvented by this catalyst system.

A novel optical multi-image data protection scheme based on phase-truncated asymmetric ciphers and 2D-CSCCM

Abstract Existing remote sensing platforms often overlook the security of the remote sensing image acquisition process, creating opportunities for potential attackers to exploit. To address this issue, this paper proposes a novel optical encryption framework (ECC_DPM) based on elliptic curves and phase truncation to ensure the secure transmission of optical keys. Furthermore, an optical encryption scheme is designed based on ECC_DPM to enable synchronous secure encryption during the remote sensing data acquisition stage, ensuring that remote sensing data remains in a ciphertext state from acquisition to storage and distribution. Finally, the proposed framework and encryption scheme are evaluated for security using a threat model and simulation experiments. The experimental results demonstrate that the encryption scheme effectively resists various statistical analysis attacks.

Annual memory in the terrestrial water cycle

Abstract. The water balance of catchments will, in many cases, strongly depend on its state in the recent past (e.g. previous days). Processes causing significant hydrological memory may persist at longer timescales (e.g. annual). The presence of such memory could prolong drought and flood risks and affect water resources over long periods, but the global universality, strength, and origin of long memory in the water cycle remain largely unclear. Here, we quantify annual memory in the terrestrial water cycle globally using autocorrelation applied to annual time series of water balance components. These time series of streamflow, global gridded precipitation, and GLEAM potential and actual evaporation, along with a GRACE (Gravity Recovery and Climate Experiment)-informed global terrestrial water storage reconstruction, indicate that, at annual timescales, memory is typically absent in precipitation but strong in terrestrial water stores (root zone moisture and groundwater). Outgoing fluxes (streamflow and evaporation) positively scale with storage, and so they also tend to hold substantial annual memory. As storage mediates flow extremes, such memory often also occurs in annual extreme flows and is especially strong for low flows and in large catchments. Our model experiments show that storage–discharge relationships that are hysteretic and strongly non-linear are consistent with these observed memory behaviours, whereas non-hysteretic and linear drainage fails to reconstruct these signals. Thus, a multi-year slow dance of terrestrial water stores and their outgoing fluxes is common; it is not simply mirroring precipitation memory and appears to be caused by hysteretic storage and drainage mechanisms that are incorporable in hydrological models.

Molecular and genomic investigation unveils Pseudomonas putida as an emerging multidrug-resistant pathogen linked to bovine clinical mastitis.

Molecular and genomic investigation unveils Pseudomonas putida as an emerging multidrug-resistant pathogen linked to bovine clinical mastitis.

Influence of soil-rock composite stratum on mechanical response and failure modes of underground utility tunnel

This research combines scaled model experiments with theoretical analysis to investigate the impact of underground utility tunnels (UUTs) on foundation bearing capacity and to examine the interaction between soil-rock composite strata and the stress-strain responses of the tunnel. The findings indicate that UUTs alter the foundation mechanism by reducing soil depth, streamlining the load transfer path, and causing stress to converge at the tunnel’s top. Additionally, the results reveal that the influence range of the tunnel on both sides is approximately 1.5 times its width and remains unaffected by the position of load application, the tunnel’s burial depth, or the width of the composite stratum. Moreover, when the width of the soil-rock composite stratum equals the width of the tunnel, the tunnel experiences a laterally flexural stress state. Within this specific stratum context, the central axis area of the tunnel roof and the connection with the side panels represent the core sensitive areas for crack initiation and propagation. In the failure scenario, the tunnel roof displays typical characteristics of fracture and depression, with the damage degree decreasing from the load center towards both ends. Meanwhile, the side panels do not exhibit characteristics of plastic deformation. This research provides a theoretical framework for the design, construction, and maintenance of UUTs, emphasizing its practical significance in engineering.

Impact of runoff schemes on global flow discharge: a comprehensive analysis using the Noah-MP and CaMa-Flood models

Abstract. Accurate estimation of flow discharge is crucial for hydrological modelling, water resources planning, and flood prediction. This study examines seven common runoff schemes within the widely used Noah-Multi-parameterisation (Noah-MP) land surface model (LSM) and evaluates their performance using ERA5-Land runoff data as a benchmark for assessing runoff and in situ streamflow observations for evaluating discharge across the globe. Then, to assess the sensitivity of global river discharge to runoff, we simulate the discharge using the Catchment-based Macro-scale Floodplain (CaMa-Flood) model across various climatic regions. The results indicate significant variability in the accuracy of the runoff schemes, with model experiments that use TOPMODEL-based runoff schemes, which are based on topography, underestimating runoff across many regions, particularly in the Northern Hemisphere, while experiments using the other runoff schemes, including default Schaake free-drainage scheme from Noah, BATS (Biosphere–Atmosphere Transfer Scheme), Variable Infiltration Capacity (VIC) scheme, and Xinanjiang scheme (XAJ), showed improved performance. Dynamic VIC consistently overestimated runoff globally. Seasonal analysis reveals substantial regional and seasonal variability. ERA5-Land and several Noah-MP schemes successfully replicated general discharge patterns of in situ observations, with ERA5-Land and Noah-MP Schaake scheme simulations closely aligning with observed data. The Noah-MP simulations demonstrated robust versatility across various land covers, soil types, basin sizes, and topographies, indicating its broad applicability. Despite overall good performance, significant biases in high-flow extremes highlight the need for continued model improvement or calibration. These findings are critical for improving global hydrological models, which are essential for developing more reliable water resources management strategies and adapting to the growing challenges posed by climate change, such as shifts in water availability and extreme flood events.

Interaction Between the Interdecadal Pacific Oscillation and Atlantic Multidecadal Variability Lowers Their Contemporaneous Correlation

AbstractThe Interdecadal Pacific Oscillation (IPO) and Atlantic Multidecadal Variability (AMV) substantially affect global climate system. Model studies suggested a fast interaction between the IPO and AMV through atmospheric teleconnections, but observations exhibit a weak IPO–AMV contemporaneous correlation. To address this paradox, we apply linear inverse model (LIM) in observations to decode the interaction. We reveal that a cancel effect of the interaction lowers the observed IPO–AMV contemporaneous correlation. When only retaining the one‐way modulation (the IPO forces the AMV or the reversed one) in the observational LIM, their correlation peaks nearly simultaneously, consistent with the fast IPO–AMV interaction in model experiments. We further demonstrate that the fast interaction is associated with both tropical and extratropical processes. Our study reconciles the discrepancy between observations and models on the IPO–AMV interaction.

Investigation of the towing resistance of a catamaran with simplified hull forms

The use of catamarans can be an effective solution for organizing mass passenger transportation on waterways. At the same time, there is a need to improve shipbuilding technology. The use of simplified hulls can be successfully employed to optimize the production process and significantly reduce construction costs. This article provides an analysis of existing studies on the resistance of vessels with simplified hull forms. It is shown that, in most cases, simplification of the hull form leads to an increase in towing resistance of up to 30%. The article presents the results of a model experiment conducted in the towing tank of the Admiral Makarov State University of Maritime and Inland Shipping. The model, with a single hull length of 2000 mm and a beam of 148 mm, was tested in calm water at three different drafts (60 mm, 80 mm, and 100 mm) and at speeds ranging from 1 m/s to 4 m/s, corresponding to Froude numbers between 0.22 and 0.90. The paper plots the towing resistance curves for the catamaran with simplified hull forms and presents the results of an experimental study of the effect of trim and draft on the towing resistance. The dependences of the residual resistance coefficient on the Froude number are examined. The data obtained during the experiment are compared with published results of propulsive performance studies of catamarans with similar principal particulars. The study provides evidence that simplifying the hull forms of high-speed multi-hull vessels negatively impacts towing resistance. It is concluded that the results obtained can be used in the design of vessels with simplified hull forms.

Climate Change Amplifies the Effects of Vegetation Restoration on Evapotranspiration and Water Availability in the Beijing–Tianjin Sand Source Region, Northern China

Evapotranspiration (ET) and water availability (WA) are critical components of the global water cycle. Although the effects of ecological restoration on ET and WA have been widely investigated, quantifying the impacts of multiple environmental factors on plant water consumption and regional water balance in dryland areas remains challenging. In this study, we investigated the spatial and temporal trends of ET and WA and isolated the contributions of vegetation restoration and climate change to variations in ET and WA in the Beijing–Tianjin Sand Source Region (BTSSR) in Northern China from 2001 to 2021, using the remote sensing-based Priestley–Taylor-Jet Propulsion Laboratory (PT-JPL) model and scenario simulation experiments. The results indicate that the estimated ET was consistent with field observations and state-of-the-art ET products. The annual ET in the BTSSR increased significantly by 1.28 mm yr−1 from 2001 to 2021, primarily driven by vegetation restoration (0.78 mm yr−1) and increased radiation (0.73 mm yr−1). In contrast, the drier climate led to a decrease of 0.56 mm yr−1 in ET. In semiarid areas, vegetation and radiation were the dominant factors driving the variability of ET, while in arid areas, relative humidity played a more critical role. Furthermore, reduced precipitation and increased plant water consumption resulted in a decline in WA by −0.91 mm yr−1 during 2001–2021. Climate factors, rather than vegetation greening, determined the WA variations in the BTSSR, accounting for 77.6% of the total area. These findings can provide valuable insights for achieving sustainable ecological restoration and ensuring the sustainability of regional water resources in dryland China under climate change. This study also highlights the importance of simultaneously considering climate change and vegetation restoration in assessing their negative impacts on regional water availability.

Optimization of the airflow organization in the photocatalytic Trombe wall with numerical model

The utilization of photocatalytic technology for the degradation of indoor volatile organic compounds (VOCs) offers the advantages of environmental friendliness, harmlessness and absence of secondary pollution. Integrating photocatalytic technology with the Trombe walls represents an effective form of building-based photocatalysis. However, there is an urgent need to improve the purification performance of photocatalytic Trombe walls. To address this issue, the impacts of co-catalysts and airflow organization on the degradation efficiency of indoor formaldehyde were investigated. TiO2 with different co-catalysts and ratios were employed. The TiO2-3% tourmaline achieved a 28.7% degradation rate within 1 h, exhibiting a 24.7% improvement compared to pure TiO2. Furthermore, the impact of air layer structure on the airflow organization and photocatalytic performance was analysed using experiment and numerical model. By symmetrically arranging two vertical ribs (5 cm wide and spaced 12 cm apart) on the collector plate surface, the formaldehyde degradation rate reached 36.7%. Moreover, a quantitative analysis was conducted to optimize the air layer structure by examining the correlation between airflow distribution and indoor VOC degradation. The formaldehyde degradation rate reached 42.0% within one hour when the air layer was arranged with three spoiler plates at the upper middle of the collector plate surface.