Analogous Experiments Research Articles

Portable Buzzer Circuit Design for Reform of Electronic Technology Experiments

As an important practical course in the field of electrical and electronic engineering, Electronic Technology Experiments not only reflect the students' familiarity with theoretical courses but also lay a solid foundation for subsequent specialized courses and post-graduation work. At the same time, it allows students to practice and test their theoretical knowledge of analog and digital electronic technologies. Through a complete project-based experimental approach, our Information Engineering Experiment Center has targeted comprehensive and exploratory reforms for both analog and digital electronic technology experiments. From the perspective of the reform outcomes, students' interest in experimental learning, project thinking skills, practical abilities, and innovative capabilities have all been significantly enhanced. This article uses the design of a pocket-sized quiz buzzer circuit as an example to elaborate on the basis of the reforms.

CO2 Hydrogenation through Electrochemical Hydrogen Activation in a Gas-Vapor Fed Reactor

An attractive concept in the chemical manufacturing industry is the adoption of a circular carbon economy, which can include continuous capture and conversion of CO2 into industrially relevant chemical feedstocks. This has driven considerable research interest in electrochemical CO2 reduction.1 Despite this popularity, major challenges remain even for the most advanced CO2 reduction reactors, including low conversion rates and energy efficiencies; moreover, in many cases, multiple carbon-containing products are generated, which add to costs for downstream separation.2 By contrast, thermochemical CO2 hydrogenation is well established and typically demonstrates higher energy efficiency and selectivity compared to electrochemical CO2 reduction.3,4 This notable contrast drives our interest in better understanding the physics that governs differences in reactivity between thermocatalytic and electrocatalytic CO2 reduction reactors. To address these questions, we are pursuing a unique approach that involves feeding humidified CO2 and H2, respectively, to the cathode and anode of an electrochemical membrane-electrode assembly (MEA). This presentation will cover initial work we have undertaken to design and validate this reactor for the study CO2 electro-reduction.The overall design of our reactor resembles a hydrogen fuel cell fed with humidified H2 and CO2. Thus, it was initially benchmarked through operation as an electrochemical hydrogen pump, wherein humidified Ar was fed to the cathode and humidified H2 was fed to the anode with Pt/C as the catalyst on each side of the membrane. Under these conditions, a cation exchange membrane (CEM) readily generated current densities in excess of 1 A/cm2 with monotonic decreases in polarization with increased temperature at fixed current. We then undertook analogous hydrogen pumping experiments using anion exchange membranes (AEM) that had been ion-exchanged with hydroxide, carbonate, and bicarbonate anions. We observed net proton transport between the anode and cathode chambers in each case, albeit with higher ionic resistance for AEMs in the bicarbonate form.We then undertook further studies to demonstrate the ability to reduce CO2 using H2 fed to the anode. This operating mode eliminates the need for a liquid anode feed, which dramatically reduces the driving force for CO2 crossover via bicarbonate formation. Moreover, the Pt/C anode catalyst is expected to oxidize hydrogen with minimal polarization, allowing the total cell polarization to be interpreted simply as the cathode potential on the RHE scale. CO2 reduction experiments were carried out using commercial Cu/C catalyst with online gas chromatography and NMR for product analysis of volatile and condensable products, respectively. Operation with a CEM yielded only H2(g) at the cathode, but initial experiments with an AEM in the carbonate/bicarbonate form gave high selectivity to ethanol at 70 oC.

Comparison of fast-neutron-induced reaction cross-sections in [formula omitted], [formula omitted], [formula omitted], [formula omitted], [formula omitted], [formula omitted], and [formula omitted] in quasi-monoenergetic fields of p+Li and d+TiT neutron sources

This paper describes cross-section measurements of fast-neutron-induced reactions using the neutron activation method. The study employed two accelerator-driven fast neutron sources, each possessing distinct characteristics during irradiation of analogous sets of samples. Specifically, the neutron source at the NPI Řež relied on the p+Li(C) reaction, while MONNET at JRC Geel utilized the d+TiT(Ag) reaction for neutron production. Building upon prior experiments conducted at NPI, we present new cross-sections for reactions, some of which suffer from a dearth of experimental data. The results presented in this paper originate from samples of Al, Au, Bi, Co, NaF, and Y that were irradiated with neutrons at energies of 17.6(3) MeV, and 18.5(4) MeV at MONNET, and an energy of 22.5(8) MeV at the NPI. Following neutron irradiation, the samples were analysed using gamma-ray spectrometry. Cross-sections of several fast-neutron-induced reactions were determined on the basis of the measurement of neutron spectra and corresponding reaction yields. By comparing the results of analogous experiments conducted in different experimental setups, it becomes possible to assess systematic uncertainties. The obtained cross-sections may contribute to the further development of both advanced nuclear reactors and to a more precise fast-neutron dosimetry.

Large scale analogue experiments in rock mechanics: new experimental facility, 3D-printed material and insertion of force transducers for stresses measurement

Abstract The aim of this paper is to present a new experimental device that was designed to perform analogue rock mechanics experiments with 3D-printed material. The device consists in the creation of two rectangular excavations (mining tunnels) in slices of 3D sand printed material. This is a true-triaxial test device that allows us to study the mechanical behaviour of reduced scale models of underground structures. The experimental protocol entails the horizontal loading of the specimen, followed by the excavation of two galleries while the specimen is maintained under a constant load. The results of the test carried out in DiMiTri show a generally logical evolution of the sensors with an increase in vertical stresses induced by the presence of excavations. This paper discusses the upcoming challenges in terms of instrumentation that will be encountered, together with the new opportunities for future research.

Martian Chaos terrain fracture geometry indicates drainage and compaction of laterally heterogeneous confined aquifers

The interlocking plateaus of martian chaotic terrain have long been inferred to relate to Hesperian outflow-channel megafloods. Numerous hypotheses have been invoked to explain the formation of the hundreds-of-kilometer-scale depressions that chaoses are found in, and the mechanisms by which the fractures formed. Hypotheses range from mechanisms involving water, e.g., ice melt, overturn of sediment-covered paleolakes, or submarine landslides, to purely magmatic processes, such as caldera formation, to exotic endmembers including clathrate decomposition. These interpretations of martian chaos are largely based on photogeological mapping of individual chaoses, and have mostly neglected analysis of the chaos fracture network and its relationships with the chaos basin. Here, we show, based on analysis of 35,964 fracture blocks across 18 different chaoses and 6 terrestrial analogs, and supported by novel volumetric measurements of chaos terrain deposits and intervening void spaces, that the geometry of martian chaoses is best explained by depressurization and compaction of an underlying confined aquifer. Block size distributions are incompatible with magma chamber collapse analog experiments. We show that sedimentary fill in chaos basins is inhomogeneously distributed, with layers thickening towards the chaos center, as in terrestrial sedimentary basins. The relationship between fracture block thickness and area is explained by the same power law that describes fracture spacing and layer thickness in weak terrestrial sandstones. The presence of some chaoses with blocks that are higher than surrounding plains implies repressurization of some sub-chaos aquifers. Hesperian-aged water or ice may remain within ∼1–3 km of the surface beneath these landforms.

Influence of Acute Inflammation on the Expression of Clock Genes in the Ovine Pars Tuberalis Under Different Photoperiodic Conditions.

The pars tuberalis (PT) plays an important role in the photoperiodic regulation of the secretory activity of the pituitary gland. Additionally, PT secretory activity may be influenced by the animal's immune status. The melatonin signal processing in PT cells occurs through the presence of melatonin receptors and the expression of molecular clock genes. This study aimed to define the effects of acute inflammation induced by intravenous administration of lipopolysaccharide (LPS) on the expression of clock genes in the PT of ewes under different photoperiodic conditions. Two analogous experiments were conducted in different photoperiods: short-day and long-day. Both experiments included 24 sheep divided into two groups: day (n = 12) and night (n = 12), further subdivided into a control group (n = 6) and a group treated with LPS (n = 6) at a dose of 400 ng/kg. Under short-day conditions, the expression of clock circadian regulator, basic helix-loop-helix ARNT like 1, cryptochrome circadian regulator (CRY) 1, 2, and casein kinase 1 epsilon genes was lower during inflammation. LPS injection increased expression of the period circadian regulator 1 gene during the night. Under long-day conditions, CRY1 mRNA level was lower during the night, while diurnal CRY2 mRNA expression was decreased after LPS injection. Our results showed that inflammation disturbed the expression of molecular clock genes in the PT; however, this influence was partly dependent on photoperiod conditions.

Contributions to the stereochemistry of zirconium oxysalts—part VI: syntheses and crystal structures of K2Zr(SO4)3∙2.5H2O, K2Zr(SeO4)3, K2Zr2O(SeO4)4, and Zr(OH)2(SeO4)·H2O

The compounds K2Zr(SO4)3·2.5H2O, K2Zr(SeO4)3, and K2Zr2O(SeO4)4 were synthesized at 200 °C by reaction of Zr2O2(CO3)(OH)2 and KHCO3 with the respective acids H2SeO4/H2SO4 and minor H2O. Zr(OH)2(SeO4)·H2O originates from an analogous experiment at 215 °C without KHCO3. All four phases form colorless crystals up to several tenths of a mm and were investigated by single crystal X-ray diffraction. K2Zr(SO4)3·2.5H2O is monoclinic, space group P21/c (No. 14), with a = 7.295(2) Å, b = 13.925(3) Å, c = 12.579(3) Å, β = 95.32(3)°, V = 1272.3(4) Å3, Z = 4, R1 = 0.025. K2Zr(SeO4)3 and K2Zr2O(SeO4)4 are both triclinic, space group P1¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P\\overline{1}$$\\end{document} (No. 2), with a = 7.570(1) Å, b = 10.500(1) Å, c = 14.400(1) Å, α = 85.55(1)°, β = 88.04(1)°, γ = 87.82(1)°, V = 1139.7(2) Å3, Z = 4, R1 = 0.049, and a = 5.400(1) Å, b = 7.328(1) Å, c = 9.642(1) Å, α = 95.81(1)°, β = 95.20(1)°, γ = 94.27(1)°, V = 376.74(4) Å3, Z = 1, R1 = 0.020, respectively. Zr(OH)2(SeO4)·H2O crystallizes in the monoclinic space group C2/c (No. 15), with a = 6.684(1) Å, b = 12.998(2) Å, c = 6.792(1) Å, β = 97.37(1)°, V = 585.14(6) Å3, Z = 2, R1 = 0.013.Graphical abstract

Particle Concentrations and Sizes for the Onset of Settling‐Driven Gravitational Instabilities: Experimental Validation and Application to Volcanic Ash Clouds

AbstractSettling‐driven gravitational instabilities (SDGIs) can form at the base of buoyant particle‐laden suspensions, modulating particle sedimentation in various settings such as meteorological and volcanic clouds, fluvial plumes, magma chambers, submarine hydrothermal plumes, or industrial emissions. These instabilities result in the formation of rapidly descending currents called ‘fingers’ within which fine particles settle faster collectively than individually. This study investigates SDGI triggering conditions underneath volcanic ash clouds through analogue experiments considering sedimentation from aqueous particle suspensions. We confirm that the conditions for which SDGIs develop are controlled by two dimensionless numbers: Bf (ratio of the characteristic finger velocity to the individual particle settling velocity); and Bi (ratio of timescale for individual particle settling to that for collective settling controlled by inertial drag). SDGIs are triggered for values of Bf and Bi > 1 for which particles are fully coupled with the flow within fingers. Using these parameters, we produce a regime diagram for the 2010 eruption of Eyjafjallajökull (Iceland) that describes particle settling as a function of particle concentration and size. More studies are needed to produce a general regime diagram accounting for the evolution of SDGIs properties with eruption and atmospheric parameters. Nonetheless, our study confirms that fingers affect sedimentation from volcanic clouds with high ash volume fractions above 10−6 vol.%. Our validation of criteria predicting the onset of fingers due to SDGIs constitutes a step forward toward the incorporation of these collective settling processes in volcanic ash transport and dispersion models.

Long-term isostatic relaxation of large terrestrial impact structures: structural characteristics inferred from scaled analogue experiments

Crater floor fractures are prominent post-cratering structural vestiges that are known from large impact craters on rocky celestial bodies. Two mechanisms have been proposed to explain the formation of crater floor fractures: emplacement of horizontal igneous sheets below crater floors and isostatic re-equilibration of crust underlying target rocks, i.e., crustal relaxation. Here, we use two-layer analogue experiments to model the deformation of lower and upper crust following crater formation, scaled to the physical conditions on Earth, to explore the structural and kinematic consequences of crustal relaxation. Specifically, the structural evolution of model upper crust was systematically analysed for various initial depths and diameters of crater floors, gleaned from previous numerical models for average continental crust. The analogue modelling results provide quantitative estimates of the duration, geometry and distribution of deformation zones in the upper crust and, for the first time, a quantitative relationship between the diameter, depth and fracture geometry of crater floors. The experiments also show that crater floor uplift is accomplished by long-wavelength subsidence of the crater periphery, which may operate on time scales of hundreds of thousands of years in nature. We conclude that patterns of natural crater floor fractures, including impact melt rock dikes known from the Sudbury and Vredefort impact structures, can be caused by long-term uplift of the crater floor, compensated by lateral crustal flow toward the crater centre.

Generalized cold-atom simulators for vacuum decay

Cold-atom analog experiments are a promising new tool for studying relativistic vacuum decay, enabling one to empirically probe early-Universe theories in the laboratory. However, existing proposals place stringent requirements on the atomic scattering lengths that are challenging to realize experimentally. Here we eliminate these restrictions and show that stable mixture between two states of a bosonic isotope can be used as a faithful relativistic analog. This greatly expands the landscape of suitable experiments, and will expedite efforts to study vacuum decay with cold atoms. Published by the American Physical Society 2024

Study on CO dispersion characteristics and isolation door control technology of refuge chamber in coal mine

To investigate the dispersion process of the underground toxic gas carbon monoxide (CO) into the refuge chamber during a mine disaster and enhance the survival rate of trapped miners, a simplified model of an underground refuge chamber and the main roadway was constructed. The impact of temperature and pressurized air volume on CO dispersion into the refuge chamber has been examined through both analog experiments and numerical simulations, and the reliability of the simulation results was verified. The results indicate that CO dispersion into the refuge chamber through the top of the protective isolation door occurs when the temperature in the refuge chamber is lower than that of the toxic gas. When the temperature of the toxic gas is higher, it tends to enter the refuge chamber through the bottom of the protective isolation door. The evolution of CO concentration in the transition chamber can be divided toxic survival chamber can be categorized into a sudden decline stage and a stable stage. And a flexible isolation door designed to control the entry of toxic gases into the refuge chamber was implemented, and its impact on CO dispersion has been compared and analyzed. When the temperature of the main roadway is 50 °C and the temperature of the refuge chamber is 20 °C, the required pressurized air volume to maintain the CO concentration within the safe threshold (24 ppm) is reduced to 69.6% of that needed without the isolation door, thereby significantly reducing the infiltration of harmful gases from the main roadway into the refuge chamber.

Multistage lithospheric drips control active basin formation within an uplifting orogenic plateau

According to GNSS/INSAR measurements, the Konya Basin in Central Anatolia is undergoing rapid subsidence within an uplifting orogenic plateau. Further, geophysical studies reveal thickened crust under the basin and a fast seismic wave speed anomaly in the underlying mantle, in addition to a localised depression in calculated residual topography (down to 280 m) over the Konya Basin, based on gravity-topography considerations. Using scaled laboratory (analogue) experiments we show that the active formation of the Konya Basin may be accounted for by the descent of a mantle lithospheric drip causing local circular-shaped surface subsidence. We interpret that the Konya Basin is developing through a secondary drip pulse that is contemporaneous with broad plateau uplift caused by a larger-scale lithospheric drip since the Miocene. The research reveals that basin evolution and plateau uplift may be linked in a multistage process of lithospheric removal during episodic development of orogenic systems.

Multiscale Parametrization Of a Friction Model For Metal Cutting Using Contact Mechanics, Atomistic Simulations, And Experiments

In this study, we developed and parametrized a friction model for finite element (FE) cutting simulations of AISI4140 steel, combining experimental data and numerical simulations at various scales. Given the severe thermomechanical loads during cutting, parametrization of friction models based on analogous experiments has been proven difficult, such that the cutting process itself is often used for calibration. Instead, our model is based on the real area of contact between rough surfaces and the stress required to shear adhesive micro contacts. We utilized microtextured cutting tools and their negative imprint on chips to orient chip and tool surfaces, enabling the determination of a combined surface roughness. This effective roughness was then applied in contact mechanics calculations using a penetration hardness model informed by indentation hardness measurements. Consistent with Bowden and Tabor theory, we observed that the fractional contact area increased linearly with the applied normal load, and the effective roughness remained insensitive to cutting fluid application. Additionally, we calculated the required shear stress as a function of normal load using DFT-based molecular dynamics simulations for a tribofilm formed at the interface, with its composition inferred from ex-situ XPS depth profiling of the cutting tools. Our friction model demonstrated good agreement with experimental results in two-dimensional FE chip forming simulations of orthogonal cutting processes, evaluated by means of cutting force, passive force, and contact length prediction. This work presents a proof of concept for a physics-based approach to calibrate constitutive models in metal cutting, potentially advancing the use of multiscale and multiphysical simulations in machining.Graphical abstract

Effects of Analog Modeling Materials on Topographic Photogrammetry (SfM) Reconstructions

AbstractAccurate topographic data are essential for quantitative structural analysis, both in natural settings and in the laboratory. The selection of modeling materials (with appropriate rheological properties) is known to be fundamental for the success of scaled physical analog experiments. However, the optical properties of analog materials and their impact on the reliability and precision of high‐resolution topographic reconstructions have not (to our knowledge) previously been assessed. Here we evaluate the effects of material composition, color, and grain size on Structure‐from‐Motion (SfM) photogrammetry reconstruction efficacy for deformed and undeformed model configurations in the laboratory. Image collections for photogrammetry are acquired from multiple camera positions with a handheld digital camera, and reconstructions are registered using ground control points in a local coordinate system. Static experiments show that low reflectivity granular materials (e.g., silica sand, volcanic ash, pumice, and Al2O3) yield relatively reliable photogrammetry data for a wide range of grain sizes (44–2,400 μm) but larger grain sizes (≥250 μm) provide more robust results. Reflective materials (e.g., glass beads, wet clay) yield less reliable point‐clouds but the addition of low‐reflectivity granular materials (e.g., Al2O3 grains) on the surface of wet clay improves reconstruction results, with higher grain densities typically yielding lower point‐cloud residuals. SfM‐photogrammetry reconstruction of deformed clay analog models tends to improve at higher extension magnitudes because of fault and associated texture development on model surfaces. We anticipate that our results will help practitioners to improve the precision and reliability of photogrammetric data acquired in the analog modeling laboratory.

Turbulence effect on disk settling dynamics

Turbulence can have a strong effect on the fall speed of snowflakes and ice crystals. In this experimental study, the behaviour of thin disks falling in homogeneous turbulence is investigated, in a range of parameters relevant to plate crystals. Disks ranging in diameter from 0.3 to 3 mm, and in Reynolds number $Re = 10\unicode{x2013}435$ , are dispersed in two air turbulence levels, with velocity fluctuations comparable to the terminal velocity. For each case, thousands of trajectories are captured and reconstructed by high-speed laser imaging, allowing for statistical analysis of the translational and rotational dynamics. Air turbulence reduces the disk terminal velocities by up to 35 %, with the largest diameters influenced most significantly, which is primarily attributed to drag nonlinearity. This is evidenced by large lateral excursions of the trajectories, which correlate with cross-flow-induced drag enhancement as reported previously for falling spheres and rising bubbles. As the turbulence intensity is increased, flat-falling behaviour is progressively eliminated and tumbling becomes prevalent. The rotation rates of the tumbling disks, however, remain similar to those displayed in still air. This is due to their large moment of inertia compared to the surrounding fluid, in stark contrast with studies conducted in water. In fact, the observed reduction of settling velocity is opposite to previous findings on disks falling in turbulent water. This emphasizes the importance of the solid-to-fluid density ratio in analogous experiments that aim to mimic the behaviour of frozen hydrometeors.

Active learning approaches in molecule pKi prediction.

During the early stages of drug design, identifying compounds with suitable bioactivities is crucial. Given the vast array of potential drug databases, it's feasible to assay only a limited subset of candidates. The optimal method for selecting the candidates, aiming to minimize the overall number of assays, involves an active learning (AL) approach. In this work, we benchmarked a range of AL strategies with two main objectives: (1) to identify a strategy that ensures high model performance and (2) to select molecules with desired properties using minimal assays. To evaluate the different AL strategies, we employed the simulated AL workflow based on "virtual" experiments. These experiments leveraged ChEMBL datasets, which come with known biological activity values for the molecules. Furthermore, for classification tasks, we proposed the hybrid selection strategy that unified both exploration and exploitation AL strategies into a single acquisition function, defined by parameters n and c. We have also shown that popular minimal margin and maximal variance selection approaches for exploration selection correspond to minimization of the hybrid acquisition function with n=1 and 2 respectively. The balance between the exploration and exploitation strategies can be adjusted using a coefficient (c), making the optimal strategy selection straightforward. The primary strength of the hybrid selection method lies in its adaptability; it offers the flexibility to adjust the criteria for molecule selection based on the specific task by modifying the value of the contribution coefficient. Our analysis revealed that, in regression tasks, AL strategies didn't succeed at ensuring high model performance, however, they were successful in selecting molecules with desired properties using minimal number of tests. In analogous experiments in classification tasks, exploration strategy and the hybrid selection function with a constant c<1 (for n=1) and c≤0.2 (for n=2) were effective in achieving the goal of constructing a high-performance predictive model using minimal data. When searching for molecules with desired properties, exploitation, and the hybrid function with c≥1 (n=1) and c≥0.7 (n=2) demonstrated efficiency identifying molecules in fewer iterations compared to random selection method. Notably, when the hybrid function was set to an intermediate coefficient value (c=0.7), it successfully addressed both tasks simultaneously.

Robotic exploration of Martian caves: Evaluating operational concepts through analog experiments in lava tubes

Caves on Mars are a tantalizing target for exploration, as they could harbor evidence of extinct or extant life, clues to the planet’s geological history, and even potential future human habitation. However, the inherent challenges of navigating unknown and challenging terrain, coupled with limited communication capabilities, pose significant obstacles for robotic exploration in these caves. This paper presents the results of an effort to evaluate different operational concepts for a mission dedicated to exploration of caves on Mars. We conducted a series of analog exploration experiments in lava tubes on Earth, testing two hypotheses: (1) that two robots are more effective than one, and (2) that high levels of autonomy are more effective than low levels of autonomy. Our findings suggest that two robots are indeed more effective, except in low autonomy cases, where more operational resources are required. We also found that full autonomy is more efficient than low autonomy, as it enables quicker exploration and detection of targets of interest. However, the low autonomy cases benefited from the operator input to acquire higher quality data, an area of autonomy requiring further development. This paper provides insight into the design of our experiments, as well as detailing the results and implications for the design of future missions to explore caves on Mars. By shedding light on the operational concepts tested and their corresponding outcomes, we contribute to the knowledge base required to formulate optimal strategies for the realization of successful cave exploration missions on the Red Planet.

Searching for a new light gauge boson with axial couplings in muon beam dump experiments

We present a formalism for new U(1) interactions involving weak hypercharge, baryon, and lepton numbers, and a possible axial symmetry generator FA in the presence of a second Brout-Englert-Higgs doublet. The resulting U boson, after mixing with the Z, interpolates between a generalised dark photon, a dark Z, and an axially coupled gauge boson. We especially focus on the axial couplings originating from FA or from mixing with the Z, determined by the scalar sector via parameters like tan β and the v.e.v. of an extra dark singlet.We explore the distinctive features of axially coupled interactions, especially in the ultrarelativistic limit, where the U boson behaves much as an axion-like particle, with enhanced interactions to quarks and leptons. This enhancement is particularly relevant for future muon beam dump experiments, since the muon mass considerably increases the effective coupling, proportional to 2mμ/mU, compared to analogous experiments with electrons.We also analyse the shape of the expected beam dump exclusion or discovery regions, influenced by U boson interactions and the experiment geometry. Different situations are considered, limited in particular by cases for which the U decays before reaching the detector, or has too small couplings to produce detectable events. We also compare to vectorially coupled bosons and axion-like pseudoscalars, highlighting the importance of understanding the parameter space for future experiment design and optimisation.

Nonlinear similarity characterisation and validation of dynamic response of ship stiffened plate structure under explosion load impacts

The similarity test of ship stiffened plate structures under underwater explosions is a cost-effective and efficient method to evaluate the vitality of ships and guide the design of their shock resistance. This study focuses on the nonlinear impact response model tests of ship stiffened plate structures and their similarity laws with actual ships. The vertical motion of the ship stiffened plate structure is characterized by the Hurst index, and an equivalent relationship between the Hurst index of the model and the prototype is derived from classical similarity law. Based on the Hurst index, a similarity transformation relationship between the strain signals of the model and prototype is established. To verify the conclusions, similarity experiments of underwater explosions were conducted on both the model and the prototype. The original signals were grouped by the natural vibration period to determine the variation of the Hurst index over time. The model experiment strain signals for each natural vibration period were converted and compared with the prototype experiment results to verify the method's effectiveness. Simultaneously, the Hurst index of the stiffened plate structure under explosive shock load and its similarity transformation relationship with the prototype were simulated and analyzed. This provides theoretical and technical support for conducting analogous nonlinear response experiments for ship underwater explosions.

Fracturing around magma reservoirs can explain variations in surface uplift rates even at constant volumetric flux

Many volcanoes show continuous but variable deformation over timescales of years to decades. Variations in uplift rate are typically interpreted as changes in magma supply rate and/or a viscoelastic response of the host rock. Here we conduct analogue experiments in the laboratory to represent the inflation of a silicic magma body at a constant volumetric flux, and measure the chamber pressure and resulting surface displacement field. We observe that dyke intrusions radiating from the magma body cause a decrease in the peak uplift rate, but do not significantly affect the spatial pattern of deformation or spatially averaged uplift rate. We identify 4 distinct phases: 1) elastic inflation of the chamber, 2) a gradual decrease in the rate of uplift and pressurisation, associated with the formation of visible cracks 3) propagation of a dyke by mode 1 failure at the crack tip and 4) a pressure decrease within the chamber. Phase 2 can be explained by either a) crack damage, which reduces the elastic moduli of the surrounding rock or b) magma filling pre-existing cracks. Thus these experiments provide alternative mechanisms to explain observed variations in uplift rate, with important implications for the interpretation of deformation patterns at volcanoes around the world.