Takumi Hachimine, Yuhwan Kwon, Cheng-Yu Kuo
et al.
Non-destructive extraction of the target internal part, such as batteries and motors, by cutting surrounding structures is crucial at recycling and disposal sites. However, the diversity of products and the lack of information on disassembly procedures make it challenging to decide where to cut. This study explores a method for non-destructive extraction of a target internal part that iteratively estimates the internal structure from observed cutting surfaces and formulates cutting plans based on the estimation results. A key requirement is to estimate the probability of the target part's presence from partial observations. However, learning conditional generative models for this task is challenging: The high dimensionality of 3D shape representations makes learning difficult, and conventional models (e.g., conditional variational autoencoders) often fail to capture multi-modal predictive uncertainty due to mode collapse, resulting in overconfident predictions. To address these issues, we propose VoxelDiffusionCut, which iteratively estimates the internal structure represented as voxels using a diffusion model and plans cuts for non-destructive extraction of the target internal part based on the estimation results. Voxel representation allows the model to predict only attributes at fixed grid positions, i.e., types of constituent parts, making learning more tractable. The diffusion model completes the voxel representation conditioned on observed cutting surfaces, capturing uncertainty in unobserved regions to avoid erroneous cuts. Experimental results in simulation suggest that the proposed method can estimate internal structures from observed cutting surfaces and enable non-destructive extraction of the target internal part by leveraging the estimated uncertainty.
Sifatul Anindho, Videep Venkatesha, Mariah Bradford
et al.
Collaborative problem solving (CPS) is a complex cognitive, social, and emotional process that is increasingly prevalent in educational and professional settings. This study investigates the emotional states of individuals during CPS using a mixed-methods approach. Teams of four first completed a novel CPS task. Immediately after, each individual was placed in an isolated room where they reviewed the video of their group performing the task and self-reported their internal experiences throughout the task. We performed a linguistic analysis of these internal monologues, providing insights into the range of emotions individuals experience during CPS. Our analysis showed distinct patterns in language use, including characteristic unigrams and bigrams, key words and phrases, emotion labels, and semantic similarity between emotion-related words.
Online advertising aims to increase user engagement and maximize revenue, but users respond heterogeneously to ad exposure. Some users purchase only when exposed to ads, while others purchase regardless of exposure, and still others never purchase. This heterogeneity can be characterized by latent response types, commonly referred to as principal strata, defined by users' joint potential outcomes under exposure and non-exposure. However, users' true strata are unobserved, making direct analysis infeasible. In this article, instead of learning the true strata, we propose a novel approach that learns users' pseudo-strata by leveraging information from an outcome (revenue) observed after the response (purchase). We construct pseudo-strata to classify users and introduce misclassification rewards to quantify the expected revenue gain of pseudo-strata-based policies relative to true strata. Within a Bayesian classification framework, we learn the pseudo-strata by optimizing the expected revenue. To implement these procedures, we introduce identification assumptions and estimation methods, and establish their large-sample properties. Simulation studies show that the proposed method achieves more accurate strata classification and substantially higher revenue than baselines. We further illustrate the method using a large-scale industrial dataset from the Criteo Predictive Search Platform.
Barry P Lawlor, Vatsa Gandhi, Guruswami Ravichandran
Background: Full-field, quantitative visualization techniques, such as digital image correlation (DIC), have unlocked vast opportunities for experimental mechanics. However, DIC has traditionally been a surface measurement technique, and has not been extended to perform measurements on the interior of specimens for dynamic, full-scale laboratory experiments. This restricts the use of DIC measurements, especially in the context of heterogeneous materials. Objective: The focus of this study is to develop a method for performing internal DIC measurements in dynamic experiments. The aim is to demonstrate its feasibility and accuracy across a range of stresses (up to 650MPa), strain rates ($10^3$-$10^6$ s$^{-1}$), and high-strain rate loading conditions (e.g., ramped and shock wave loading). Methods: Internal DIC is developed based on the concept of applying a speckle pattern at an inner-plane of a transparent specimen. The high-speed imaging configuration is then focused on the internal speckle pattern. During the dynamic experiment, in-plane, two-dimensional deformations are measured via correlation of the internal speckle pattern. Results: The internal DIC experimental technique is successfully demonstrated in both the SHPB and plate impact experiments. In the SHPB setting, the accuracy of the technique is excellent throughout the deformation regime, with measurement noise of approximately 0.2% strain. For plate impact experiments, the technique performs well, with error and measurement noise of 1% strain. Conclusion: The internal DIC technique has been developed and demonstrated to work well for full-scale dynamic high-strain rate and shock laboratory experiments, and the accuracy is quantified. The technique can aid in investigating the physics and mechanics of the dynamic behavior of materials, including local deformation fields around dynamically loaded material heterogeneities.
We present a numerical model of fractal-structured aggregates in low-Reynolds-number flows. Assuming that aggregates are made of cubic particles, we first use a boundary integral method to compute the stresses acting on the boundary of the aggregates. From these external stresses, we compute the stresses within the aggregates in order to gain insights on their breakup, or disaggregation. We focus on systems in which aggregates are either settling under gravity or subjected to a background shear flow and study two types of aggregates, one with fractal dimension slightly less than two and one with fractal dimension slightly above two. We partition the aggregates into multiple shells based on the distance between the individual cubes in the aggregates and their center of mass and observe the distribution of internal stresses in each shell. Our findings indicate that large stresses are least likely to occur near the far edges of the aggregates. We also find that, for settling aggregates, the maximum internal stress scales as about 7.5% of the ratio of an aggregate's apparent weight to the area of the thinnest connection, here a single square. For aggregates exposed to a shear flow, we find that the maximum internal stress scales roughly quadratically with the aggregate radius. In addition, after breaking aggregates at the face with the maximum internal stress, we compute the mass distribution of sub-aggregates and observe significant differences between the settling and shear setups for the two types of aggregates, with the low-fractal-dimension aggregates being more likely to split approximately evenly. Information obtained by our numerical model can be used to develop more refined dynamical models that incorporate disaggregation.
The present work is devoted to the analysis of the internal structure of relativistic jets under the condition that the velocity of the plasma flow at the jet axis vanishes. It is shown that in spite of the seemingly fundamental difference in the formulation of the problem at the axis, the key properties of the internal structure of such relativistic jets remain the same as for nonzero velocity along the axis. In both cases, at a sufficiently low ambient pressure, a dense core appears near the axis, the radius of which is close to the size of the light cylinder.
Nicolas Lanchon, Daniel Odens Mora, Eduardo Monsalve
et al.
We present laboratory experiments on turbulence in a linearly stratified fluid driven by an ensemble of internal gravity waves which approaches statistical homogeneity and axi-symmetry. In a way similar to several recent experimental works, non-linearities develop through the establishment of a set of internal wave modes at discrete frequencies, when the forcing amplitude is increased. We show that the most energetic of these modes are resonant eigenmodes of the fluid domain. The discretization of the energy in frequency and wavenumber associated to the emergence of these modes prevents the flow from approaching a regime described by the Weak/Wave Turbulence Theory, in which a forward cascade carried by a statistical ensemble of weakly non-linear waves in an infinite domain forms an energy continuum in the frequency and wavenumber spaces. We then show that the introduction of slightly tilted panels at the top and at the bottom of the fluid domain allows to inhibit the emergence of the discrete wave modes. In this new configuration, the non-linear regime results in a continuum of energy over one decade of frequencies which is mainly carried by internal gravity waves verifying the dispersion relation. We therefore achieved a turbulent flow approaching a three-dimensional internal wave turbulence regime with no discretization of the energy in the frequency and wavenumber domains. These results constitute a significant step forward in the search of the laboratory observation of a fully-developed weakly-non-linear internal-gravity-wave turbulence.
We consider online allocation problems with concave revenue functions and resource constraints, which are central problems in revenue management and online advertising. In these settings, requests arrive sequentially during a finite horizon and, for each request, a decision maker needs to choose an action that consumes a certain amount of resources and generates revenue. The revenue function and resource consumption of each request are drawn independently and at random from a probability distribution that is unknown to the decision maker. The objective is to maximize cumulative revenues subject to a constraint on the total consumption of resources. We design a general class of algorithms that achieve sub-linear expected regret compared to the hindsight optimal allocation. Our algorithms operate in the Lagrangian dual space: they maintain a dual multiplier for each resource that is updated using online mirror descent. By choosing the reference function accordingly, we recover dual sub-gradient descent and dual exponential weights algorithm. The resulting algorithms are simple, efficient, and shown to attain the optimal order of regret when the length of the horizon and the initial number of resources are scaled proportionally. We discuss applications to online bidding in repeated auctions with budget constraints and online proportional matching with high entropy.
The mechanisms of phase change of argon during picosecond laser internal ablation are studied using molecular dynamics simulations. It is found that propagation of stress wave and fluctuation of temperature are periodical. The phase change process from solid to liquid to supercritical fluid then back to solid occurs as combined results of heating and the propagation of tensile stress wave induced by the laser pulse and the limited internal space.
To study the fundamental physics of complex multiphase flow systems using advanced measurement techniques, especially the electrical capacitance tomography (ECT) approach, this article carries out an initial literature review of the ECT method from a point of view of signal processing and algorithm design. After introducing the physical laws governing the ECT system, we will focus on various reconstruction techniques that are capable to recover the image of the internal characteristics of a specified region based on the measuring capacitances of multi-electrode sensors surrounding the region. Each technique has its own advantages and limitations, and many algorithms have been examined by simulations or experiments. Future researches in 3D reconstruction and other potential improvements of the system are discussed in the end.
This paper presents a contemporary review of vertical coupling in the atmosphere and ionosphere system induced by internal waves of lower atmospheric origin. Atmospheric waves are primarily generated by meteorological processes, possess a broad range of spatial and temporal scales, and can propagate to the upper atmosphere. A brief summary of internal wave theory is given, focusing on gravity waves, solar tides, planetary Rossby and Kelvin waves. Observations of wave signatures in the upper atmosphere, their relationship with the direct propagation of waves into the upper atmosphere, dynamical and thermal impacts as well as concepts, approaches, and numerical modeling techniques are outlined. Recent progress in studies of sudden stratospheric warming and upper atmospheric variability are discussed in the context of wave-induced vertical coupling between the lower and upper atmosphere.
An equation of motion of the mass point with internal degrees of freedom in scalar potential $U$ depending on relative coordinates and time, velocity and accelerations is obtained both for non-relativistic and relativistic case. In non-relativistic case a generalization of the energy conservation law follows, if $\partial U / \partial t = 0$ fulfilled. A concept of work is generalized to relativistic case, leading to corresponding integral of motion, if $\partial U / \partial τ= 0$ fulfilled, where $τ$ is proper time of the point. In neglecting an internal degrees of freedom and absence of interaction this integral of motion gives standard Special Relativity.
On the example of a particular problem, the theory of vacancies, a new form of kinetic equations symmetrically incorporation the internal and free energies has been derived. The dynamical nature of irreversible phenomena at formation and motion of defects (dislocations) has been analyzed by a computer experiment. The obtained particular results are extended into a thermodynamic identity involving the law of conservation of energy at interaction with an environment (the 1st law of thermodynamics) and the law of energy transformation into internal degree of freedom (relaxation). The identity is compared with the analogous Jarzynski identity. The approach is illustrated by simulation of processes during severe plastic deformation, the Rybin kinetic equation for this case has been derived.
We show that an internal localization mobility edge can appear around the Fermi energy in graphene by introducing impurities in the split-band regimen, or by producing vacancies in the lattice. The edge appears at the center of the spectrum and not at the band edges, in contrast with the usual picture of localization. Such result is explained by showing that the bipartite nature of lattice allows to renormalize the Hamiltonian, and the internal edge appears because of frustration effects in the renormalized lattice. The size in energy of the spectral region with localized states is similar in value to that observed in narrow gap semiconductors.
We evaluate the partial widths for internal conversions in the Higgs decays to two photons. For the Higgs masses of interest at LHC in the range of 100-150 GeV, the conversions to pairs of fermions represent significant fraction of Higgs decays.
This article looks at the changing approach that both the Australian High Court and the House of Lords have taken over the last 70 or so years in interpreting taxation legislation. This changing approach reflects underlying changes in community attitudes. Particular consideration is given to the High Court’s changing interpretation of the general anti‐avoidance provision (formerly s 260 and now Part IVA of the Income Tax Assessment Act 1936). The article focuses on the observations of Justice Graham Hill and his Honour’s views as to the correct approach for a court to take in interpreting taxation legislation. His Honour made it clear that a court should adopt a purposive approach by applying the ordinary meanings of the words used, to give effect to the legislative purpose behind the legislation. This approach requires looking to the context of the legislation in its widest sense to give effect to the objects of the legislation. However, such an approach should not be used to advance any personal theories of justice. Justice Hill was widely regarded as having been the leading Australian tax judge for more than a decade before his untimely death in 2005.