Space Compression Research Articles

Application of systems of orthogonal functions for formation of sign space in image classification methods

The subject of the article's research is the improvement of structural methods of image classification in computer vision systems. The goal is to reduce computational costs for classification by implementing a device for decomposing image description components using a system of orthogonal functions and implementing feature space compression models. Applied methods: ORB key point detector, set theory apparatus and vector spaces, metric models for determining relevance to sets of multidimensional vectors, theory of orthogonal decomposition of vectors, elements of probability theory, software modeling. Obtained results: modifications of the image classification method based on the introduction of orthogonal data decomposition in vector space were developed, models were proposed for data compression in the transformed feature space, Tanimoto metric was introduced for image comparison, a threshold selection method was established for determining equivalent description components. The effectiveness of the developed modifications of the classifier depends on the selection of a subset of functions for decomposition, the metric for comparing descriptions, and the method of determining the equivalence threshold. The implementation of the apparatus of orthogonal functions not only reduced computational costs tenfold, but also ensured sufficiently high indicators of classification performance and interference resistance. The practical significance of the work is the construction of new models of the image classifier in the transformed space of features, confirmation of the functionality, speed and immunity of the proposed modifications on examples of images, the creation of a software application for the implementation of the developed classification methods in computer vision systems.

Explicit Data-Driven Small-Signal Stability Constrained Optimal Power Flow

This paper proposes a data-driven small-signal stability constrained optimal power flow (SSSC-OPF) method with high computational efficiency. Instead of repeating the computational expense small-signal stability analysis via differential and algebraic equations during the iterative OPF process, a computationally cheap surrogate constraint for small-signal stability is developed. To reduce the learning difficulty for small-signal stability boundaries, an efficient sample generation strategy is proposed with sampling space compression. This allows us to use the support vector machine (SVM) with a kernel function to derive the explicit data-driven surrogate constraint for small-signal stability. Penalty factor optimization is proposed to compensate for the error caused by SVM. The learned small-signal stability constraint is embedded into the OPF model for generator control. An examination strategy is also developed to avoid the small-signal instability of re-dispatch caused by the error of the data-driven surrogate model. Comparison results with other model-based and data-driven methods on the IEEE 39-bus and 118-bus systems demonstrate the high computational efficiency and economic benefits of the proposed method.

NMRI online observation of coal fracture and pore structure evolution under confining pressure and axial compressive loads: A novel approach

Quantitative characterization of the spatial distribution, content and heterogeneity of fracture and pore structure (FPS) in coal reservoirs under confining pressures and axial compressive loads is significant for the engineering of coal bed methane. A novel online observation approach that combines nuclear magnetic resonance imaging with triaxial loading techniques is employed to achieve the visualization and full-scale quantitative characterization of the evolution of FPS in coals in the laboratory. The relationship between the stress states and FPS evolution was formulated. The results show that the spatial distribution of the FPS evolution process of coal samples can be divided into four stages: initial pore and fracture compaction closure, pore and fracture stable growth, pore and fracture unstable growth, and failure stages. As the deviatoric stress increases, the content of the adsorption pores, the heterogeneity of the adsorption space, and the gas adsorption capacity of coal samples gradually increase. In contrast, the seepage pore and fracture content as well as the permeability of coal samples decrease first and then increase. The heterogeneity of the seepage space of coal samples initially increases and then decreases. The maximum compression of seepage space and increase of adsorption space are 4.742% and 14.743%, respectively.

Ultra-Fast Approximate Inference Using Variational Functional Mixed Models

ABSTRACT While Bayesian functional mixed models have been shown effective to model functional data with various complex structures, their application to extremely high-dimensional data is limited due to computational challenges involved in posterior sampling. We introduce a new computational framework that enables ultra-fast approximate inference for high-dimensional data in functional form. This framework adopts parsimonious basis to represent functional observations, which facilitates efficient compression and parallel computing in basis space. Instead of performing expensive Markov chain Monte Carlo sampling, we approximate the posterior distribution using variational Bayes and adopt a fast iterative algorithm to estimate parameters of the approximate distribution. Our approach facilitates a fast multiple testing procedure in basis space, which can be used to identify significant local regions that reflect differences across groups of samples. We perform two simulation studies to assess the performance of approximate inference, and demonstrate applications of the proposed approach by using a proteomic mass spectrometry dataset and a brain imaging dataset. Supplementary materials for this article are available online.

Analytic investigation on error of heat flux measurement and data processing for large curvature models in hypersonic shock tunnels

Due to short test time, heat conduction was considered as transient in hypersonic shock tunnels. The heat flux measurement and data processing were operated basing on one-dimensional semi-infinite heat conduction theory. However, for models with local large curvature or small radius, it resulted in significant compression or expansion of space for heat transfer, or lateral heat conduction, which made the hypothesis of one-dimensional unsatisfied and errors. In this paper, approximate solutions for the unsteady heat conduction in cylindrically convex and concave shells were established, and were used for further analysis of the errors, with forms of heating load, location and curvature radius of heated surface taken into consideration.

A lightweight 3D UNet model for glioma grading

Objective. Glioma is one of the most fatal cancers in the world which has been divided into low grade glioma (LGG) and high grade glioma (HGG), and its image grading has become a hot topic of contemporary research. Magnetic resonance imaging (MRI) is a vital diagnostic tool for brain tumor detection, analysis, and surgical planning. Accurate and automatic glioma grading is crucial for speeding up diagnosis and treatment planning. Aiming at the problems of (1) large number of parameters, (2) complex calculation, and (3) poor speed of the current glioma grading algorithms based on deep learning, this paper proposes a lightweight 3D UNet deep learning framework, which can improve classification accuracy in comparison with the existing methods. Approach. To improve efficiency while maintaining accuracy, existing 3D UNet has been excluded, and depthwise separable convolution has been applied to 3D convolution to reduce the number of network parameters. The weight of parameters on the basis of space and channel compression & excitation module has been strengthened to improve the model in the feature map, reduce the weight of redundant parameters, and strengthen the performance of the model. Main results. A total of 560 patients with glioma were retrospectively reviewed. All patients underwent MRI before surgery. The experiments were carried out on T1w, T2w, fluid attenuated inversion recovery, and CET1w images. Additionally, a way of marking tumor area by cube bounding box is presented which has no significant difference in model performance with the manually drawn ground truth. Evaluated on test datasets using the proposed model has shown good results (with accuracy of 89.29%). Significance. This work serves to achieve LGG/HGG grading by simple, effective, and non-invasive diagnostic approaches to provide diagnostic suggestions for clinical usage, thereby facilitating hasten treatment decisions.

Space squeezing optics: Performance limits and implementation at microwave frequencies

Optical systems often largely consist of empty space as diffraction effects that occur through free-space propagation can be crucial for their function. Contracting these voids offers a path to the miniaturization of a wide range of optical devices. Recently, a new optical element—coined “spaceplate”—has been proposed, which is capable of emulating the effects of diffraction over a specified propagation distance using a thinner non-local metamaterial [Reshef et al., Nat. Commun. 12, 3512 (2021)]. The compression factor of such an element is given by the ratio of the length of free-space that is replaced to the thickness of the spaceplate itself. In this work, we test a prototype spaceplate in the microwave spectral region (20–23 GHz)—the first such demonstration designed to operate in ambient air. Our device consists of a Fabry–Pérot cavity formed from two reflective metasurfaces with a compression factor that can be tuned by varying the size of perforations within each layer. Using a pair of directive horn antennas, we measure a space compression factor of up to ∼6 over a numerical aperture (NA) of 0.34 and a fractional bandwidth of 6%. We also investigate the fundamental trade-offs that exist between the compression factor, transmission efficiency, NA, and bandwidth of this single resonator spaceplate design and highlight that it can reach arbitrarily high compression factors by restricting its NA and bandwidth.

Aggressive Osteoblastoma in adolescents: Radiological case report

In this article we represent an 18-year-old female with progressive back pain and neurologic symptoms due to a large heterogenous mass centered in posterior elements of lower thoracic vertebrae with prominent soft tissue extension into paravertebral and epidural space and subsequent central cord compression along with severe adjacent inflammatory changes. Considering patient age, lesion location and characteristics, aggressive Osteoblastoma, eosinophilic granuloma, and with lower probability of Ewing sarcoma were included in the differential list, which aggressive Osteoblastoma was confirmed after pathologic examination.

Rural and urban youth: do the socio-cultural gaps remain?

The purpose of this work is search for arguments for the validity of the hypothesis about leveling in the youth environment of the socio-cultural gaps traditional for urban and rural areas, realized in the family and social spheres of life. The work focuses on young people's ideas about territorial identity, cultural and leisure practices and forms of civic engagement, and the desirable form of partnership (marriage) relations. The information base of the study was survey data of young people aged 18-35 living in urban and rural areas of Vologda oblast. Youth is a socio-demographic group that forms the basis of the human potential of population. Globalization, digitalization, virtualization, large-scale projects for development of social infrastructure, road repairs and at the same time space compression (urbanization) significantly affect the worldview and lifestyle of young people. In addition, due to the successful experience of distance learning and employment formats, the impetus for the development of which was the COVID-19 pandemic, a hypothesis has arose about the convergence of the socio-cultural characteristics of urban and rural youth. In view of the consistently representative proportion of rural youth (a quarter of the group), the continuing centripetal nature of migration, and the importance of understanding the differences between urban and rural spaces, the study seems to be relevant for both theory and practice of youth policy. On the basis of sociological survey data, it was revealed that the urban and rural youth have similar views on family and marriage. Young people are focused on having few children and are tolerant of cohabitation. However, rural youth are more "family-oriented", when conditions are created, they are more ready for having many children and labile for support measures. Urban residents have a more pronounced territorial identity, although collectivism is more often manifested by rural residents. Further development of digitalization, new remote forms of education and employment, provision of public and other services, will facilitate holding back young people in rural areas, stimulate reurbanization (most likely, in suburbanization formats), thus reducing the socio-cultural gap between the city and the village.

Conservation of spatial volume and the emergence of gravity and electromagnetism

The universe is a structured, logical system obeying many natural laws. This essay proposes an additional law termed the conservation of spatial volume. This refers to spacetime’s ability to be displaced, compressed, expanded, and stretched to conserve geometric volume. In addition, space appears to possess Cauchy-like elasticity characteristics measured by the gravitational constant G. It is postulated that space has qualities of an energy density field, which is termed the “spatial energy field” or SEF in this essay. The SEF in all of its parts is a metric of energy field curvature tensors assigned to every coordinate in spacetime. It is proposed that space resists volume displacement by mass and reacts with a counter-force equal to the object’s inertia mass. This is because the compression of space from the displacement of mass creates a gravitational field. The gravitational field represents an increase in spatial density surrounding the object. An increase in spatial density is measured by the change in permittivity ε, permeability μ, and refractive index n, physical parameters of the vacuum. Thus, gravity would be considered an emergent response of spacetime attempting to conserve its volume by the reciprocal curvature force of space. In regard to electromagnetism, electric and magnetic fields are geometric in origin and, therefore, part of spacetime. It is proposed that spacetime has specific properties related to the emergence of electrical fields via the Poynting vector. This is influenced by electric permittivity εo. Magnetic fields appear to emanate from space based on the Lorentz force. This is influenced by magnetic permeability μo. Both the Poynting vector energy flow and the corresponding Lorentz force are the reaction of space counteracting forces of electricity and magnetism while conserving spatial volume. It appears that electromagnetism could be considered a twisting torsion of spacetime. Space appears to mediate electrical and magnetic fields; it provides a framework for transmitting electromagnetic waves as well as momentum-gravitational waves. Gravity and electromagnetism are related, emerging from a common origin, which appears to be the energy of spacetime itself.

Posterior fossa extradural hematoma - clinical presentation and outcome

Background: Posterior Fossa Extra Dural Hematoma (PFEDH) is a rare entity but certain crucial structures are supposed to be injured. Because of limited space in the posterior fossa, a clinical small volume of hematoma can deteriorate patients. Therefore timely diagnosis and prompt intervention are required.
 Objective: This study is done to analyse factors like demographic profile, mode of injury, clinical features in relation to PFEDH and its management and how they influence the outcome.
 Materials & methods: This is a retrospective analysis of patients who presented with PFEDH from July 2016 to July 2021 at RNT Medical College and M.B. group of Hospitals Udaipur, India. Patients were evaluated on the basis of demographic profile, mode of injuries, GCS on admission & discharge, and associated radiological findings.
 Result: A total of 25 patients with PFEDH were included in this study. Amongst these, 18 (72%) were males, and10 (40%) were less than 18 years of age. On admission 19 (76%) had GCS 13-15.22 (88%) patients underwent surgery and 3 (12%) were planned for conservative management. At 6-month follow-up, 22 (88%) patients had good outcomes with GOS 3-5 and 1 was lost to follow up while 2 (8%) had poor outcomes with GOS 1-2.
 Conclusion: GCS on admission is a good predictor of outcome. The volume of EDH was one of the key factors in deciding the line of management. PFEDH can sometimes be rapidly fatal due to expansion of hematoma and compression of posterior cranial fossa space which leads to brain stem compression therefore time management is the most important factor for a good outcome.

Enhanced performance of Si-based Li-ion batteries through elastic cushioning with hollow graphene shells

Silicon (Si) is a promising anode material for next-generation Li-ion batteries. The nanometer-sized Si could alleviate the pulverization caused by large volume changes during deep cycling. However, compression between agglomerated Si particles causes Si cracking and electrode failure. Considering this, we engineered a mechanical cushioning space between Si particles via elastic hollow graphene shells (GSs) to flexibly buffer volume changes and maintain the stability of the electrode structure. The stress generated from the Si volume expansion during lithiation was mechanically buffered and gently released by compression of the hollow space of the GS. In this Si/GS composite electrode, GS also reduced the local agglomeration of Si particles and effectively improved the overall conductivity. Considering these advantages, the designed Si/GS electrode showed an enhanced cycling performance with more than 1200 mA h g−1 at 0.8 A g−1 and an excellent rate capability of 1025 mA h g−1 at 4 A g−1 after 200 cycles.

Three-dimensional coseismic deformation of the 2016 MW7.8 Kaikuora, New Zealand earthquake obtained by InSAR and offset measurements

The 2016 MW7.8 Kaikoura earthquake struck the northern part of south Island, New Zealand, within the active and complex Australia–Pacific plate boundary system. Firstly, we used the InSAR method to obtain coseismic LOS deformation fields based on SAR images and applied offset tracking methods to obtain offset measurements based on optical satellite images. The maximum displacement of about 6 m is detected in the direction away from the satellite on the south-west side and also towards the satellite on the north-east side. The 3D deformation field is then resolved by the combination of these measurements with a least-square solve method, and comparisons with 3 components of GPS stations show good consistency. Despite complex features demonstrated in the 3D deformation field, there are still clear spatial correlations between surface deformation and faults distribution. It reveals that more than ten faults were ruptured during the earthquake, including some faults were previously understudies for their tectonic activities. The maximum horizontal deformation of about 10 m occurs along the Kekerengu fault with the vertical deformation up to 2 m. The 3D deformation shows that the mainshock is a multi-segments faulting with a rupture process of strike-slip, compression, transpressional rupture and strike-slip in space along the NE direction.

Atypical visual field asymmetries in redundancy masking.

Redundancy masking is the reduction of the perceived number of items in repeating patterns. It shares a number of characteristics with crowding, the impairment of target identification in visual clutter. Crowding strongly depends on the location of the target in the visual field. For example, it is stronger in the upper compared to the lower visual field and is usually weakest on the horizontal meridian. This pattern of visual field asymmetries is common in spatial vision, as revealed by tasks measuring, for example, spatial resolution and contrast sensitivity. Here, to characterize redundancy masking and reveal its similarities to and differences from other spatial tasks, we investigated whether redundancy masking shows the same typical visual field asymmetries. Observers were presented with three to six radially arranged lines at 10° eccentricity at one of eight locations around fixation and were asked to report the number of lines. We found asymmetries that differed pronouncedly from those found in crowding. Redundancy masking did not differ between upper and lower visual fields. Importantly, redundancy masking was stronger on the horizontal meridian than on the vertical meridian, the opposite of what is usually found in crowding. These results show that redundancy masking diverges from crowding in regard to visual field asymmetries, suggesting different underlying mechanisms of redundancy masking and crowding. We suggest that the observed atypical visual field asymmetries in redundancy masking are due to the superior extraction of regularity and a more pronounced compression of visual space on the horizontal compared to the vertical meridian.

Arthroscopic reconstruction of scaphoid nonunions

Minimally invasive arthroscopically assisted reconstruction of scaphoid nonunions. Delayed union or nonunion of the scaphoid with sclerosis and with indication for bone transplantation. Limited arthritic changes at the radial styloid. Severe humpback deformity with dorsal intercalated segment instability. Midcarpal arthritic changes. Supine position with the forearm upright and in neutral position, the elbow flexed by90°, axial traction of 3 to 4 kg. Standard wrist arthroscopy via the 3-4 and the 4-5portal and the midcarpal joint via the radial and ulnar portal, respectively, with sodium chloride as arthroscopy medium. Change of the optic to the ulnar midcarpal portal and opening of the nonunion with an elevator via the radial midcarpal portal. Resection of the sclerosis with a3.0 mm burr while irrigating the joint. Harvesting of cancellous bone via the second extensor compartment. On the hand table, closed reduction by joy-stick K‑wires if needed and insertion of K‑wires for the scaphoid screw. Insertion of the screw without entering of the distal thread into the bone. Arthroscopic insertion of the bone transplant by ablunt drill sleeve via the radial portal with steady compression by the obturator. Complete insertion of the screw under arthroscopic control of the compression of the nonunion space with arthroscopic control of stability with the probe. Six weeks forearm cast including the thumb metacarpophalangeal joint, radiographic control and non-load bearing movements for two more weeks, CT scan in the oblique sagittal plane after 8weeks, and increase of load, as well as physiotherapy on demand depending on the radiographic results. To date, 17patients with amean age of the nonunion of 18months were treated. In14patients, bony union was achieved after 8weeks. In one patient, an extraosseous screw placement was corrected. In another patient with extraosseous screw placement, persisting nonunion was treated with an angular stable plate. One scaphoid demonstrated an asymptomatic tight nonunion after 14months, while one scaphoid with sclerosis of the proximal pole did not heal.

Stretch-Contract Operator in the Ellipsoidal Approximation of the Minkowski Sum of Convex Sets

The space expansion-contraction operator was originally developed to solve mathematical programming problems. However, it can be successfully applied to solve the problem of ellipsoidal approximation of the information set in the state space analytically specified. In this case, a main property of the operator - space compression is used to minimize the approximating ellipsoid by a multidimensional volume. The paper shows the use of the specified expansion-contraction operator to approximate a set of attainability of the linear control system as an example. The main goal of the paper is to give analytical and geometric representations of the specified operator in order to show its action in the approximation problem. For this purpose, the paper shows an analytical derivation of the operator and a geometric illustration of each parameter of the operator. The results of minimum approximation modeling by this operator compared with other known solutions have been also presented. The simulation results are given both numerically and graphically. Based on the results of comparison, conclusions are made and recommendations are given in the use of ellipsoidal approximation of information sets according to different criteria for minimizing the approximating ellipsoid. Typical examples of ellipsoidal approximation, which show when it is expedient to use the proposed of expansion-contraction operator, have been given.

Moving toward autonomous solutions: Exploring the spatial and temporal dimensions of business ecosystems

Incorporating smart digital technologies has been an inevitable next step in transforming manufacturing firms, evident in the emergence of digital servitization. In this paper, we examine how change toward digital servitization is unfolding in the offshore wind industry. We report on an in-depth longitudinal case study of a solution provider and other actors in an ecosystem. We contribute by drawing on activity theory to explain the development of autonomous solutions as epistemic objects. Although digital solutions suggest the compression of time and space, we find instead that spatial-temporal expansion helps us understand the development and co-evolution of business ecosystems, which we describe as being in a state of flux, akin to the movement of an amoeba. Furthermore, we explain how epistemic objects, mediated by using tools, enable the move toward autonomous solutions that create value. In so doing, we argue that ‘autonomous’ solutions are never completely autonomous in the sense that they can exist on their own as objects; they require many other mediating tools to bring them into existence and through which they evolve. Lastly, our findings provide valuable insights into how practitioners may develop advanced digital solutions in their ecosystem to expand expertise networks and foster closer collaboration.

Quasimonoenergetic Proton Acceleration via Quantum Radiative Compression

Dense high-energy monoenergetic proton beams are vital for wide applications, thus modern laser-plasma-based ion-acceleration methods are aiming to obtain high-energy proton beams with energy spread as low as possible. In this work, we put forward a quantum radiative compression method to postcompress a highly accelerated proton beam and convert it to a dense quasimonoenergetic one. We find that when the relativistic plasma produced by radiation-pressure acceleration collides head on with an ultraintense laser beam, large-amplitude plasma oscillations are excited due to quantum radiation reaction and the ponderomotive force, which induce compression of the phase space of protons located in its acceleration phase with negative gradient. Our three-dimensional spin-resolved quantum electrodynamics (QED) particle-in-cell simulations show that hollow-structure proton beams with a peak energy approximately $\mathrm{GeV}$, relative energy spread of few percents, and number ${N}_{p}\ensuremath{\sim}{10}^{10}$ (or ${N}_{p}\ensuremath{\sim}{10}^{9}$ with a $1\mathrm{%}$ energy spread) can be produced in near-future laser facilities, which may fulfill the requirements of alternative applications, such as, for radiography of ultrathick dense materials, or as injectors of hadron colliders.

Cyclic test and numerical analysis of the seismic performance of concrete columns reinforced by HRB600 steel bars

As a new type of high-strength steel bar, hot-rolled ribbed bar (HRB) 600 reinforcement has an obvious yield platform and high elongation. To better understand the seismic performance of HRB600 steel bar reinforced concrete columns, cyclic tests are first conducted to examine the effect of the reinforcement strength, stirrup spacing, and axial compression ratio on their seismic performance. Then, finite element (FE) models of the column specimens are established by OpenSees, and the accuracy is verified by comparison with the experimental results. Finally, parametric analysis is conducted to investigate the effects of the concrete strength, longitudinal reinforcement strength, volume-stirrup ratio, and stirrup strength on the seismic performance of concrete columns. The research results show that the column specimens reinforced by HRB600 reinforcement can achieve an excellent drift ratio capacity of 4.2% when the axial load ratio is 0.5, and have a deformation capacity similar to that of normal-strength bar reinforced concrete columns. The established FE model can simulate well the behavior of HRB600 bar reinforced concrete columns under cyclic loading. The parametric analysis shows that when adopting equal strength replacement of longitudinal reinforcement, the columns built by high- and normal-strength reinforcement have similar strength and deformation capacity, but the high-strength bar reinforced columns have a slightly smaller energy dissipation.

Sliding Scale Theory of Attention and Consciousness/Unconsciousness.

Attention defined as focusing on a unit of information plays a prominent role in both consciousness and the cognitive unconscious, due to its essential role in information processing. Existing theories of consciousness invariably address the relationship between attention and conscious awareness, ranging from attention is not required to crucial. However, these theories do not adequately or even remotely consider the contribution of attention to the cognitive unconscious. A valid theory of consciousness must also be a robust theory of the cognitive unconscious, a point rarely if ever considered. Current theories also emphasize human perceptual consciousness, primarily visual, despite evidence that consciousness occurs in diverse animal species varying in cognitive capacity, and across many forms of perceptual and thought consciousness. A comprehensive and parsimonious perspective applicable to the diversity of species demonstrating consciousness and the various forms—sliding scale theory of attention and consciousness/unconsciousness—is proposed with relevant research reviewed. Consistent with the continuous organization of natural events, attention occupies a sliding scale in regards to time and space compression. Unconscious attention in the form of the “cognitive unconscious” is time and spaced diffused, whereas conscious attention is tightly time and space compressed to the present moment. Due to the special clarity derived from brief and concentrated signals, the tight time and space compression yields conscious awareness as an emergent property. The present moment enhances the time and space compression of conscious attention, and contributes to an evolutionary explanation of conscious awareness.