Deformation Space Research Articles

Emergence of High-Order Deformation in Rotating Transfermium Nuclei: A Microscopic Understanding.

The rotational properties of the transfermium nuclei are investigated in the full deformation space by implementing a shell-model-like approach in the cranking covariant density functional theory on a three-dimensional lattice, where the pairing correlations, deformations, and moments of inertia are treated in a microscopic and self-consistent way. The kinematic and dynamic moments of inertia of the rotational bands observed in the transfermium nuclei ^{252}No, ^{254}No, ^{254}Rf, and ^{256}Rf are well reproduced without any adjustable parameters using a well-determined universal density functional. It is found for the first time that the emergence of the octupole deformation should be responsible for the significantly different rotational behavior observed in ^{252}No and ^{254}No. The present results provide a microscopic solution to the long-standing puzzle on the rotational behavior in No isotopes, and highlight the risk of investigating only the hexacontetrapole (β_{60}) deformation effects in rotating transfermium nuclei without considering the octupole deformation.

LVAs in a Pedicled SIEA Flap for the Treatment of Recurrent Lymphocele of the Groin Using Superficial Veins of the Flap for Lymphovenous Anastomosis: A Case Report and Literature Review.

Persistent lymphocele of the groin is a complication of groin surgery that can severely impact the quality of life. The restoration of the interrupted lymphatic pathway is considered by many authors the ideal treatment to prevent a recurrence. However, multiple aspiration procedures and surgical revisions can compromise the availability of local veins needed for a lymphovenular bypass surgery. In addition, surgical debridement of a long-standing lymphocele can generate extensive dead space and contour deformity. A flap delivering additional venules for trans-flap lymphovenular anastomoses (LVAs) can overcome both problems by providing soft tissue and competent veins harvested outside the zone of injury. A successful case of severe groin lymphocele treated with trans-flap LVAs from an abdominal-based flap is presented. The patient was referred to us for a recurrent lymphocele developed in the right groin after lipoma excision that persisted despite multiple surgical attempts. After the identification of patent and draining inguinal lymphatic vessels, a pinch test was used to design a mini-abdominoplasty superficial inferior epigastric artery flap. The superficial veins of the cranial incision were identified and anastomosed to the lymphatic vessels after the pedicled flap harvested and insetted in the groin. The early restoration of lymphatic drainage and the optimal aesthetic outcome supports the combined approach offered by trans-flap LVAs as a valuable therapeutic option for severe and persistent lymphocele.

Light-evoked deformations in rod photoreceptors, pigment epithelium and subretinal space revealed by prolonged and multilayered optoretinography

Phototransduction involves changes in concentration of ions and other solutes within photoreceptors and in subretinal space, which affect osmotic pressure and the associated water flow. Corresponding expansion and contraction of cellular layers can be imaged using optoretinography (ORG), based on phase-resolved optical coherence tomography (OCT). Until now, ORG could reliably detect only photoisomerization and phototransduction in photoreceptors, primarily in cones under bright stimuli. Here, by employing a phase-restoring subpixel motion correction algorithm, which enables imaging of the nanometer-scale tissue dynamics during minute-long recordings, and unsupervised learning of spatiotemporal patterns, we discover optical signatures of the other retinal structures’ response to visual stimuli. These include inner and outer segments of rod photoreceptors, retinal pigment epithelium, and subretinal space in general. The high sensitivity of our technique enables detection of the retinal responses to dim stimuli: down to 0.01% bleach level, corresponding to natural levels of scotopic illumination. We also demonstrate that with a single flash, the optoretinogram can map retinal responses across a 12° field of view, potentially replacing multifocal electroretinography. This technique expands the diagnostic capabilities and practical applicability of optoretinography, providing an alternative to electroretinography, while combining structural and functional retinal imaging in the same OCT machine.

A Lagrangian filling for every cluster seed

We show that each cluster seed in the augmentation variety contains an embedded exact Lagrangian filling. This resolves the matter of surjectivity of the map from Lagrangian fillings to cluster seeds. The main new technique to produce these Lagrangian fillings is the construction and study of a quiver with potential associated to curve configurations. We prove that its deformation space is trivial and show how to use it to manipulate Lagrangian fillings with L\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$\\mathbb{L}$\\end{document}-compressing systems via Lagrangian disk surgeries.

Research and Application of High Efficiency Pressure Relief Technology for Ultra-high Pressure Hydraulic Slotted Coal Seam

In order to solve the technical problem of efficient pressure relief of the impact coal seam, the principle of ultra-high pressure hydraulic slit relief and anti-impact technology is expounded, and the ultra-high pressure hydraulic slit device with working pressure up to 100MPa is selected as the pressure relief equipment of coal seam. The field test of high-efficiency pressure relief by ultra-high pressure hydraulic slotting in impact coal seam was carried out. The test showed that the slotting radius of No.3 coal in Tangkou Mine could reach 1.5m under the condition of 100MPa slotting pressure. The stress variation in seam area and large diameter drilling area is compared and analyzed. The stress in seam area decreases significantly by 40%. The stress of bolt (cable) and the deformation of surrounding rock in the slit area are investigated. Compared with the large-diameter pressure relief area, the increase value of bolt is lower and the increase value of cable is significant in the hydraulic slit test area. The technical benefits of hydraulic slotting and large-diameter drilling are summarized and compared. The engineering quantity of drilling with ultra-high pressure hydraulic slotting is reduced by 60%, and the coal output is 2.5 times of that of large-diameter drilling. The large-diameter drilling provides limited pressure relief space for coal seam, but the ultra-high pressure hydraulic slotting technology can effectively increase the deformation space in the coal body and reduce the elastic energy stored in the coal pillar, so as to achieve a good pressure relief effect. The field test shows that compared with large diameter drilling, ultra-high pressure hydraulic slotting technology has remarkable effects of pressure relief, shock absorption and shock prevention.

Embedded parallel-actuated technology for deformable space segmented mirror

The deployable segmented space imaging system is an important solution for future ultra-large aperture space optical systems. To achieve the imaging capability of an equivalent aperture monolithic mirror, it requires not only to ensure the positional accuracy in the cophasing process, but also to have extremely high surface accuracy and curvature consistency of the sub-mirrors. However, this work is extremely challenging due to the manufacturing error of the sub-mirrors and the complex space environment. Active optical technology can ensure the surface shape accuracy of the spliced mirror by controlling the mirror surface deformation and compensating for the wavefront aberration. This article compares and analyzes the control ability of two types of deformable mirrors actuated by vertical and parallel methods. We explored the characteristics of the influence function mathematical models of the two types of actuation forms and compared the aberration and curvature correction abilities of them through finite element analysis, summarizing the advantages of the parallel actuation forms. Finally, a 300mm aperture embedded parallel-actuated deformable mirror was designed and manufactured, and relevant experiments were conducted to verify its adjustment ability. By comparing and analyzing the experimental results with the design results, the adjustment ability of the embedded parallel-actuated deformable mirror was verified.

Study of the Effect of Seepage–Cyclic Load Coupling Disturbance on the Physical Field in Old Urban Underground Spaces

The safety and sustainability of urban underground spaces have become crucial considerations in development projects. Seepage and cyclic loads are the principal reasons for the instability and failure of old underground space structures. This study investigates the variations in physical fields of underground spaces in cities under the coupling disturbance of seepage and cyclic loads, focusing on underground civil air defense engineering in Beijing as a case study. Different seepage conditions and the effects of seepage–cyclic load coupling were simulated using the numerical calculation software Plaxis 3D V20. The results show that change in groundwater can affect the deformation of underground space, and the severity is related to the quantity and intersection state of tunnels, the location of rivers above, and the strength of materials. The coupling effect of seepage–cyclic load on urban underground space structures is more serious than that of a single percolation. Decrease in material strength and high traffic loads are the principal reasons for the failure of underground structures. A 30% decrease in material strength causes the displacement to increase almost 1.5 times, and maximum displacement under different traffic loads can vary by 3 times. This study holds significant implications for the design, maintenance, and engineering management of underground spaces, emphasizing the importance of sustainable practices in urban development and infrastructure.

Conceptual Configuration Analysis of Tetrahedral-Octahedral Heterogeneous Unit and Topological Design of Shape Morphing Mechanism

Abstract The truss static structure system has excellent large load and lightweight characteristics. It is easy to embed actuators by substituting specific members in the structure and has the potential for multidimensional space deformation. Inspired by uniform tessellation structures, this article proposes a novel shape morphing mechanism (SMM) based on the combined design of tetrahedral-octahedral heterogeneous units (TOHUs). The relationship between the motion properties and driving configuration of the tetrahedral-octahedral units is analyzed to determine their conceptual configuration based on graph theory. Then, the weighted graph, adjacency matrix, and connection rules are evaluated to synthesize the conceptual structure for the truss mechanism. The results show that this configuration can allow multidimensional continuous deformations, including span, bend, sweep, and twist. A prototype is built to verify its deformability. Finally, the stiffness performance is analyzed based on the matrix displacement method. This research provides a comprehensive design method for constructing SMM, expands the range of combinable units and connection methods, and offers theoretical guidance for the innovative design of multidimensional deformation SMM in aerospace.

International legal aspects of regulation of forced migration

The article examines the peculiarities of the legal regulation of the international legal regulation of forced migration and the determination of prospects for its development. The opinion is expressed that the emergence of new technical means and methods of production, means of communication, changes in the social sphere of states, deformation of the geopolitical space and many other factors of a socio-economic and political nature caused the growth of migration flows in the world. It has been established that the state policy in the field of population migration is designed to ensure the regulation of population migration movements, overcoming their negative consequences both for the international community, each country in general, and each migrant in particular.
 It is noted that the Universal Mechanism for the Protection of the Rights of Forced Migrants is based on the Convention Relating to the Status of Refugees of 1951 and the Protocol Relating to the Status of Refugees of 1967. In addition, it is emphasized that an important role in ensuring the international protection of refugees and asylum seekers is also played by the Recommendations acts adopted within individual UN bodies, as well as other universal documents supplementing the specified legal array.
 Based on the analysis of scientific points of view and legislation, the author comes to the conclusion that the main norms of international and regional acts in the field of forced migration, which serve as guidelines for domestic systems of legislation and law enforcement, as well as for global tools for solving the problems of forced migration in general, are the principles non-discrimination, non-refoulement, family unity, interstate cooperation, international solidarity and observance of the best interests of the child. The need to create effective mechanisms for the implementation of international legal documents in the field of forced migration, to strengthen the international responsibility of states, and to determine the optimal methods of final or long-term solutions to the refugee problem was noted.

Research and Optimization of Extrusion Tap Structure Based on Numerical Simulation and Experimental Analysis.

In order to enhance the quality of thread processing by tap, a systematic analysis of its forming mechanism and factors affecting forming quality is conducted. Effects of the number of edges, the amount of shovel back, the extrusion cone, the calibration part and the extrusion cone angle on the torque and temperature are achieved by finite element analysis and experiments. From the perspective of reducing torque and temperature during the forming process, the optimal combination of tap structural parameters for machining M22×2 internal threads on 42CrMo4 high-strength steel are further obtained through orthogonal optimization. The results show that, unlike the cutting process of threads, the extrusion forming process of threads is a net forming process in which metal undergoes plastic deformation in a limited space, and the metal material continuously flows along the edge of the V-shaped groove of the tap, gradually piling up to form the thread tooth shape. This also caused a noticeable lack of flesh at the top of the extruded thread teeth. Better quality threads can be obtained by machining with optimized structural parameters. The maximum torque and temperature during the machining process are reduced by 22.86% and 20.31%, respectively. The depth of the hardened layer increased by 0.05 mm, and the root and top hardness of the teeth increased by 10 HV0.2 and 5 HV0.2, respectively.

Hwang-Oguiso invariants and frozen singularities in special geometry

In Special Geometry there are two inequivalent notions of “Kodaira type” for a singular fiber: one associated with its local monodromy and one with its Hwang-Oguiso characteristic cycle. When the two Kodaira types are not equal the geometry is subtler and its deformation space gets smaller (“partially frozen” singularities). The paper analyzes the physical interpretation of the Hwang-Oguiso invariant in the context of 4d N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{N} $$\\end{document} = 2 QFT and describes the surprising phenomena which appear when it does not coincide with the monodromy type. The Hwang-Oguiso multiple fibers are in one-to-one correspondence with the partially frozen singularities in M-theory compactified on a local elliptic K3: a chain of string dualities relates the two geometric set-ups. Paying attention to a few subtleties, this correspondence explains in purely geometric terms how the “same” Kodaira elliptic fiber may have different deformations spaces. The geometric computation of the number of deformations agrees with the physical expectations. At the end we briefly outline the implications of the Hwang-Oguiso invariants for the classification program of 4d N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{N} $$\\end{document} = 2 SCFTs.

CatFormer: Category-Level 6D Object Pose Estimation with Transformer

Although there has been significant progress in category-level object pose estimation in recent years, there is still considerable room for improvement. In this paper, we propose a novel transformer-based category-level 6D pose estimation method called CatFormer to enhance the accuracy pose estimation. CatFormer comprises three main parts: a coarse deformation part, a fine deformation part, and a recurrent refinement part. In the coarse and fine deformation sections, we introduce a transformer-based deformation module that performs point cloud deformation and completion in the feature space. Additionally, after each deformation, we incorporate a transformer-based graph module to adjust fused features and establish geometric and topological relationships between points based on these features. Furthermore, we present an end-to-end recurrent refinement module that enables the prior point cloud to deform multiple times according to real scene features. We evaluate CatFormer's performance by training and testing it on CAMERA25 and REAL275 datasets. Experimental results demonstrate that CatFormer surpasses state-of-the-art methods. Moreover, we extend the usage of CatFormer to instance-level object pose estimation on the LINEMOD dataset, as well as object pose estimation in real-world scenarios. The experimental results validate the effectiveness and generalization capabilities of CatFormer. Our code and the supplemental materials are avaliable at https://github.com/BIT-robot-group/CatFormer.

Expansive soil improvement using industrial bagasse and low-alkali ecological cement

Cement is the primary material used for mitigating expansive soil hazards due to its easy availability and relatively low cost. However, the most commonly used ordinary Portland cement renders the soil strongly alkaline after treatment, and the development of cracks in the soil is not effectively controlled under the influence of wet-dry cycles following cement stabilization. These two drawbacks significantly impact both the ecological environment and the strength of the cement-stabilized expansive soil. This study innovatively proposes an improvement to the method of cement stabilization of expansive soil by incorporating low-alkali ecological cement and industrial sugarcane bagasse (a byproduct of sugar production). After assessing the basic physical properties of the expansive soil, it was improved by mixing with industrial bagasse and low-alkali ecological cement. Through experiments on dry-wet cycles, soil-water characteristic curve tests, direct shear tests, and electron microscopy scans, we explored the enhancement of the expansive soil. Our focus was on the development of cracks, soil moisture migration patterns, changes in shear strength, and microstructural alterations. The following conclusions were drawn from the experiments: i. Compared to the method of ordinary Portland cement stabilization, the pH of expansive soil improved by low-alkali ecological cement combined with industrial sugarcane bagasse is more suitable for plant growth. ii. The unique tubular structure of industrial sugarcane bagasse provides elastic space for soil deformation, inhibiting the development of soil cracks. iii. The water retention capacity of expansive soil significantly increases after improvement with low-alkali ecological cement and industrial sugarcane bagasse. Within the range of matrix suction for plant growth, soil moisture changes more slowly, providing a more stable water supply for plants. iv. The combination of 1.2% industrial sugarcane bagasse and 7% low-alkali ecological cement exhibits the highest shear resistance, maintaining strength exceeding that of untreated expansive soil after five wet-dry cycles. v. SEM analysis confirms the effectiveness of industrial sugarcane bagasse and low-alkali ecological cement in improving expansive soil. This study improved the widely used cement stabilization method for expansive soil in practical engineering applications. Additionally, it introduced an additional utilization pathway for industrial bagasse residue waste. This research provides a new direction and reference for the combination of waste utilization and natural disaster management in the treatment of expansive soil hazards.

The principal bundle structure of continuum mechanics

In this paper it is shown that the structure of the configuration space of any continua is what is called in differential geometry a principle bundle. A principal bundle is a structure in which all points of the manifold (each configuration in this case) can be naturally projected to a manifold called the base manifold, which in our case represents pure deformations. All configurations projecting to the same point on the base manifold (same deformation) are called fibers. In this paper, it is shown that each of these fibers is then naturally isomorphic to the Lie group SE(3) representing pure rigid body motions. Furthermore, it will be shown that it is possible to define intrinsically (coordinate free), what is called a connection and this allows to split any continua motion in a rigid body sub-motion and a deformable one in a completely coordinate free way. As a consequence of that it is then possible to properly define a pure deformation space on which an elastic energy can be defined and this will be related to other literature on intrinsic strain which has not shown the geometric structure which will be presented in this work. This will be shown using screw theory and Lie groups. Screw theory is vastly used in the analysis of rigid body mechanisms but is not normally used to analyse continua. The paper will also relate known concepts of continua like helicity and enstrophy to screw theory concepts which will become evident by the presented construction.

Infinitesimal Deformations of Some Quot Schemes

Abstract Let $E$ be a vector bundle on a smooth complex projective curve $C$ of genus at least two. Let $\mathcal{Q}(E,d)$ be the Quot scheme parameterizing the torsion quotients of $E$ of degree $d$. We compute the cohomologies of the tangent bundle $T_{\mathcal{Q}(E,d)}$. In particular, the space of infinitesimal deformations of $\mathcal{Q}(E,d)$ is computed. Kempf and Fantechi computed the space of infinitesimal deformations of $\mathcal{Q}({\mathcal O}_{C},d)\,=\, C^{(d)}$ [ 11, 19].

Recovery of the spatially-variant deformations in dual-panel PET reconstructions using deep-learning

Dual panel PET systems, such as Breast-PET (B-PET) scanner, exhibit strong asymmetric and anisotropic spatially-variant deformations in the reconstructed images due to the limited-angle data and strong depth of interaction effects for the oblique LORs inherent in such systems. In our previous work, we studied time-of-flight (TOF) effects and image-based spatially-variant PSF resolution models within dual-panel PET reconstruction to reduce these deformations. The application of PSF based models led to better and more uniform quantification of small lesions across the field of view (FOV). However, the ability of such a model to correct for PSF deformation is limited to small objects. On the other hand, large object deformations caused by the limited-angle reconstruction cannot be corrected with the PSF modeling alone. In this work, we investigate the ability of deep-learning (DL) networks to recover such strong spatially-variant image deformations using first simulated PSF deformations in image space of a generic dual panel PET system and then using simulated and acquired phantom reconstructions from dual panel B-PET system developed in our lab at University of Pennsylvania. For the studies using real B-PET data, the network was trained on the simulated synthetic data sets providing ground truth for objects resembling experimentally acquired phantoms on which the network deformation corrections were then tested. The synthetic and acquired limited-angle B-PET data were reconstructed using DIRECT-RAMLA reconstructions, which were then used as the network inputs. Our results demonstrate that DL approaches can significantly eliminate deformations of limited angle systems and improve their quantitative performance.

Twin spacing and grain size dependent tensile deformation mechanism of a nano-ploycrystalline Ni-based alloy

It is easy to form twins in Ni-based wrought superalloys with low stacking fault energy, but the effect of grain size and twin spacing on mechanical properties in nano-ploycrystalline Ni-based alloys is rarely studied. Based on the composition of a novel Ni-based wrought superalloy, molecular dynamics simulations were used to study the effect of grain size and twin spacing on the deformation behavior of the Ni57Cr19Co19Al5 alloy. The results show that the elastic modulus and tensile strength of the nano-polycrystalline Ni57Cr19Co19Al5 alloy exhibit clear grain size dependence. As the grain size exceeded 16 nm, the elastic modulus remained unchanged. The tensile strength and grain size satisfy the Hall–Petch relationship, and the dislocation motion dominates the plastic deformation. For the grain size below 16 nm, the elastic modulus decreases as the grain size decreases. The tensile strength and the grain size exhibit an inverse Hall–Petch relationship. The grain boundary sliding and grain torsion mechanisms dominated plastic deformation in the nano-polycrystalline Ni57Cr19Co19Al5 alloy without twin. In the nano-polycrystalline Ni57Cr19Co19Al5 alloy containing twins, the twin boundaries inhibited the torsion of grains, and grain boundary sliding dominated plastic deformation.

A closed-form expression of a ductile Fracture Limit Surface (FLS) for general plane stress deformation paths

Ductile fracture in metals is a complex phenomenon caused by the nucleation, growth, and aggregation of micron-sized voids. Existing theoretical models for fracture use experimentally determined Fracture Limit Curves (FLCs) in two-dimensional strain space, which require multiple curves to account for anisotropic effects. This paper proposes a practical closed-form analytical function for a Fracture Limit Surface (FLS) which has a conical shape in the Elastic Distortional Deformation Space (EDDS). The EDDS is a space generated by the components of the elastic distortional metric of the microstructural vectors that characterize elastic distortional deformations and the orientations of anisotropy. The FLS is determined by simulating only four experimental FLCs using a large deformation Eulerian formulation of the microstructural vectors and it depends only on the current state of elastic distortional deformation. It is shown that the failure limit points predicted by the FLS agreed very well with those predicted using a popular evolution equation for damage-based ductile fracture. Path-independence of the FLS is also examined using experimental data. In addition, the example of a B-pillar forming process is presented to show that the FLS can be applied to practical engineering problems with material points that experience general loading paths.

Deformation spaces, rescaled bundles, and the generalized Kirillov formula

In this paper, we construct a smooth vector bundle over the deformation to the normal cone \mathrm{DNC}(V,M) through a rescaling of a vector bundle E\to V , which generalizes the construction of the spinor rescaled bundle over the tangent groupoid by Nigel Higson and Zelin Yi. We also provide an equivariant version of their construction. As the main application, we recover the Kirillov character formula for the equivariant index of Dirac-type operators. As another application, we get an equivariant generalization of the description of the Witten and the Novikov deformations of the de Rham–Dirac operator using the deformation to the normal cone obtained recently by O. Mohsen.

Revisiting the island of hexadecapole-deformation nuclei in the A ≈ 150 mass region: focusing on the model application to nuclear shapes and masses

Based on the potential-energy-surface calculation, the impact of different deformation degrees of freedom on a single-particle structure and binding energies in nuclei around 152Nd, located on one of the hexadecapole-deformation islands, is analyzed in a multi-dimensional deformation space. Various energy maps, curves and tables are presented to indicate nuclear properties. The calculated equilibrium deformations and binding energies with different potential parameters are compared with experimental data and other theories. It is found that the inclusion of the hexadecapole deformations, especially the axial one, can improve the theoretical description of both nuclear shapes and masses. In addition, our calculated potential-energy curve shows that a critical deformation-point, β 2 ≈ 0.4, exists—the triaxial (hexadecapole) deformation effect can be neglectable but the hexadecapole (triaxial) one plays an important role before (after) such a critical point.