Principal Lines Research Articles

Magnetic configurations related to the coronal heating and solar wind generation. II. Quantitative characterization of active-region magnetic structure based on the geometric property of force-free α

Abstract We investigate the geometric property of a scalar position function, the so-called force-free α, to see how it quantitatively characterizes the magnetic structure of solar active regions, which is reminiscent of the electrostatic potential whose geometric property provides information on the structure of electrified objects. Scatter plots of (α, ∇2α) show characteristic shapes representing twisted magnetic field configurations in two model active regions, one of which is formed by an emerging magnetic flux tube composed of strongly twisted field lines while the other is formed by a weakly twisted flux tube. By generalizing the concept of an axis field line in a uniformly twisted cylindrical flux tube, we introduce a topological object called the principal field line to represent magnetic structure reconstructed using a force-free field model. The principal field line and associated scatter plot of (α, ∇2α) provide a method reminiscent of active-region radiography, which could be used for quantitative classification of active regions with those magnetic configurations responsible for heating coronal plasmas, generating solar winds, and producing potentially harmful coronal explosive phenomena.

Discrete orthogonal structures

To represent smooth geometric shapes by coarse polygonal meshes, visible edges often follow special families of curves on a surface to achieve visually pleasing results. Important examples of such families are principal curvature lines, asymptotic lines or geodesics. In a surprisingly big amount of use-cases, these curves form an orthogonal net. While the condition of orthogonality between smooth curves on a surface is straightforward, the discrete counterpart, namely orthogonal quad meshes, is not. In this paper, we study the definition of discrete orthogonality based on equal diagonal lengths in every quadrilateral. We embed this definition in the theory of discrete differential geometry and highlight its benefits for practical applications. We demonstrate the versatility of this approach by combining discrete orthogonality with other classical constraints known from discrete differential geometry. Orthogonal multi-nets, i.e. meshes where discrete orthogonality holds on any parameter rectangle, receive an in-depth analysis.

Design of porous structure based on the Voronoi diagram and stress line for better stress shielding relief and permeability

In the process of artificial metal bone implantation, the mismatch of elastic modulus and bad permeability behavior lead to obvious stress shielding and poor bone tissue ingrowth. For these problems, this paper proposed a new design method of the variable porosity porous structure based on the stress line and Voronoi diagram. In the design process, the principal stress line was determined by mechanical finite element analysis, which controlled the seeds distribution of the 3D Voronoi diagram, making local porosity conforms to the stress distribution. In addition, the designed samples were fabricated through laser powder bed fusion (L-PBF) technology with TC4 powders. The mechanical characteristics were evaluated by static mechanical simulation with ABAQUS and compression tests, and the permeability characteristics were analyzed by fluid simulation with COMSOL and in vitro and vivo test. The research results showed that the designed structure obtained the relatively low elastic modulus and higher mechanical strength, the designed structure has closer permeability characteristics to the reconstructed natural bone, and was conducive to cell proliferation. So the porous structure based on the stress line and Voronoi diagram might have good application potential in the bionic design of bone implants.

Bio-inspired-based structures optimization for additive manufacturing using metaheuristic Kriging

Lightweight cellular structures are investigated intensively in additive manufacturing and require optimization strategies to distribute both patterns, cross-sections sizes and type, and even materials. There exist several parametric optimization techniques that permit not only obtaining lightweight structures but also ensuring maintaining the rigidity. Among these techniques, design of experiments is time-consuming, and the values of the optimal parameters are estimated based on their possible range rather than being determined precisely. An original scientific strategy is to use the Kriging swarm optimization technique to achieve the global optimum using a minimal amount of computer simulations. Therefore, the objective of this paper is to determine the optimal cross-sections of structures using bio-inspired “L-systems”. These L-systems-based structures were created and distributed along the directions of the principal stress lines (PSLs), then mimicking material growth and distribution inside biological structures. Two PSLs directions were separately investigated for each load case; the first direction is used as a guide for the growth of L-systems and the second one serves for branch extensions and limitations. To do so, a metamodel is used upon particle swarm optimization technique (PSO) and several case studies are conducted to improve the stiffness-to-weight ratio while respecting the additive manufacturability.

A new design method for the openings of shell structures under the dual control of principal stress lines and stress contours

Current design software lacks high precision and effective control in handling complex shell opening designs. This study develops a new workflow for generating shell openings based on the exceptional modeling advantages of Grasshopper, a visual programming language integrated with the Rhino software. The process contains two critical subroutines developed in Python for data processing and transformation. One is a selection tool based on the K-nearest neighbors classification algorithm for processing principal stress line data. The classification result is the guideline for shell meshing, which substantially improves the structural rationality of mesh shells generated based on dynamic equilibrium methods and particle spring systems. Another tool developed in this study based on the computer vision library OpenCV provides the functionality to read and process stress image data. In addition, this subroutine allows multi-level control of shell opening dimensions according to stress contours. In contrast with the conventional method, the new method efficiently brings shell form under the dual control of principal stress lines and stress contours for the first time. The obtained shell-opening results indicate increased freedom in layout, shape, and smoothness. The method is applied to a free-form shell, and three typical practical examples are presented to demonstrate its structural efficiency and visual effect.

Human Organoids, their Perspective, and Applications for Personalized Therapy: Rapid Review

Organoids are cell cultures that are three-dimensional (3D) and include some of the most significant traits of the organ being modeled. These in vitro culture techniques can recreate some activities of the represented organ, to enable these cell types specific to organs to self-organize into a spatial arrangement comparable to that found in vivo. Adult stem cells from tissue samples, a single adult stem cell, or pluripotent stem cells that have undergone directed differentiation can all be used to create organoids. Since some organoid model systems have an active stem cell population, the organoids can be greatly expanded. Organoid culturing methods as of now have been generated to mimic the tissue architectures of the three principal cell lines. Although there are several techniques for cultivating cells that are unique to different tissues, Typically, Matrigel® or another acceptable extracellular matrix is used to implant the appropriate tissue-specific progenitor cells or pluripotent stem cells. The stem cell population is maintained by the cells being cultivated in cell culture environments with certain growth factors that closely resemble the in vivo signals needed. Under these circumstances, the interconnected cells multiply and self-organize into 3D organoids that can last forever and be accessed by many systems. In addition, these cultures have proven to be exceptionally stable genetically throughout passage; after 3 months in culture, whole genome sequencing of liver organoids made through clonal expansion from only one hepatic progenitor cell just one equivalent base mutation was found. In vitro cell culture is being revolutionized by organoids, which offer useful and medically accurate models that accurately reproduce the essential features of the modelled tissue.

Interpreting the magnetic signatures and radiometric indicators within Kogi State, Nigeria for economic resources

The mineral and geothermal potentials of part of Kogi State was investigated through the interpretation of aeromagnetic and radiometric data of the study area. The analysis targeted bridging the gap of insufficient geophysical information of sub-crustal resources that could be of economic value within the area of study. Vertical derivatives, analytical signal and spectral depth analysis were used for the interpretation of the aeromagnetic data while the concentration and ternary images of the three radiogenic elements were used for the interpretation of the radiometric data. The result of first vertical derivative was helpful in delineating mineral potent lineaments labelled F1 to F8. The lineaments were seen trending E-W and NE-SW direction. A principal fault line F6 tends to separate the regions of sediments to the south-east and basement geologic formations to the south-western regions. Result of the analytical signal amplitude revealed regions with shallow intrusive magnetic rocks having high amplitudes ranging from 0.152 to 0.557 nT/m, while regions with magnetic rock intruding into sedimentary formations at greater depths, have medium to low amplitudes ranging from 0.014 to 0.136 nT/m. Regions delineated to be altered through hydrothermal process coincided with areas of major magnetic lineaments. The lineaments which could be fractures, faults or shear zones usually serve as conduits for mineral deposits during hydrothermal process. Result of potassium_thorium ratio map showed evidence of hydrothermal alteration in the NW and SW regions of study area. These regions of alterations also corresponds to regions where major lineaments were mapped and thus represent regions with significant potency for mineralisation. Result of spectral depth analysis on the aeromagnetic data showed that peak values of geothermal gradient and Heat flow were 27°C/km and 68 mW/m2 respectively, the values were recorded at the North-eastern part of study area, at the lower end of Koton-Karfe and part of Lokoja where the shallowest Curie point depth of 24 km also occurred. The estimated values of heat flow falls below the range of 80 to 100 mW/m2 recommended as threshold for a good source of geothermal energy, hence the region will not be prospectively good for a cost effective geothermal energy exploration. In order to assess the heat production within the study area due to activities of radioelements, a comparative analysis of the concentration of the three radiogenic elements was carried out. A relatively high radiogenic heat production (RHP) value of 3.4 μW/m3 was recorded at the North-western region indicating high occurrence of radioactivity within the granitic rocks. The (RHP) value of 3.4 μW/m3 is slightly below 4.0 μW/m3 which is a recommended value for a good source of geothermal energy.

Principal Stress Trajectories in Plasticity under Plane Strain and Axial Symmetry

The two families of principal stress trajectories can be regarded as an orthogonal curvilinear coordinate system under plane strain and axial symmetry. Under plane strain, the equilibrium equations in conjunction with a yield criterion comprise a statically determinate system. Under axial symmetry, a statically determinate system results from the above equations supplemented with the hypothesis of Haar von Karman. In both cases, the compatibility equations for mapping the principal line coordinate system to a given coordinate system show that the scale factors of the former satisfy a simple algebraic or transcendental equation for many yield criteria. Using this equation, one can develop a method for reducing boundary value problems in plasticity to purely geometric problems. The method is independent of any flow rule that can be chosen to calculate displacement or velocity fields, as well as independent whether elastic strains are included. The present paper summarizes available results related to using principal stress trajectories in plasticity and emphasizes the advantages of the method above.

Salient-Centeredness and Saliency Size in Computational Aesthetics

We investigate the optimal aesthetic location and size of a single dominant salient region in a photographic image. Existing algorithms for photographic composition do not take full account of the spatial positioning or sizes of these salient regions. We present a set of experiments to assess aesthetic preferences, inspired by theories of centeredness, principal lines, and Rule-of-Thirds. Our experimental results show a clear preference for the salient region to be centered in the image and that there is a preferred size of non-salient border around this salient region. We thus propose a novel image cropping mechanism for images containing a single salient region to achieve the best aesthetic balance. Our results show that the Rule-of-Thirds guideline is not generally valid but also allow us to hypothesize in which situations it is useful and in which it is inappropriate.

Concurrent shape and build orientation optimization for FDM additive manufacturing using the principal stress lines (PSL)

Additive Manufacturing (AM) with the consisting constantly evolving technologies is a particularly popular research area. Based on the shape forming freedom, size, shape, and topology optimization techniques can be validated by AM produced parts. However, in every manufacturing process, AM also has some adverse inherent properties. One and maybe the most significant optimization problem is the mechanical anisotropy caused by the layered structure. In this paper, a simultaneous build orientation and shape optimization method is presented. Both of the approaches are intended to increase the mechanical performance of the produced parts. Shape optimization was accomplished by varying the cross-section of the beam geometries, based on the angle between a PSL section and the characteristic load direction. To test the efficiency and validate the method 2D structures (with relatively small 3rd dimension) and their tensile properties were tested. Based on the results, we can prove that the PSL method works and help to increase the mechanical performance by 19.2% with only 7.8% size increment.

A Comprehensive Review of the State-of-the-Art on Security and Privacy Issues in Healthcare

Currently, healthcare is critical environment in our society, which attracts attention to malicious activities and has caused an important number of damaging attacks. In parallel, the recent advancements in technologies, computing systems, and wireless communications are changing healthcare environment by adding different improvements and complexity to it. This article reviews the current state of the literature and provides a holistic view of cybersecurity in healthcare. With this purpose in mind, the article enumerates the main stakeholders and architecture implemented in the healthcare environment, as well as the main security issues (threats, attacks, etc.) produced in healthcare. In this context, this work maps the threats collected with a widely used knowledge-based framework, MITRE ATT&CK, building a contribution not seen so far. This article also enumerates the security mechanisms created to protect healthcare, identifying the principal research lines addressed in the literature, and listing the available public security-focused datasets used in machine-learning to provide security in the medical domain. To conclude, the research challenges that need to be addressed for future research works in this area are presented.

중국 광시 베이부만의 물류경쟁력 평가 및 분석에 관한 연구

China’s strategy of “One Belt, One Road” brings considerable development opportunities to the Beibu Gulf in Guangxi Province. With considerations to development situations of the Beibu Gulf, influencing factors of logistics development in the Beibu Gulf were analyzed and an evaluation system of logistics competitiveness of ports was established in the present study. Moreover, competitiveness of ports was investigated using the entropy weight method. Some strategies to improve logistics competitiveness of ports in the Beibu Gulf in Guangxi Province were proposed according to analysis results. first, Ports in the Beibu Gulf shall take the initiative to expand capacities, increase berths, develop importance of basic functions, further increase cargo passing capacity, realize multi-mode cooperation of “railway, highway and waterway”, shorten transport mileage, save operating cost, and thereby increase cargo handling capacity. second, A port logistics center with industrial clusters and integrated functions is built up by centering at modernized ports. Ports shall set up waterway, highway and railway combined transport center to match with modern logistics system. Moreover, traffic facilities shall be perfected to relieve traffic pressure at ports and increase their collecting and distribution efficiencies. third, Facing with new economic situations, the Beibu Gulf spares no effort to promote structural reform and take stable growth and promoting structural reform as the principal line of economic work of the year. Centered at the goal of economic development, it is adjusting industrial structures, changing development mode, improving people’s living standards and perfect social insurance system. Under the premise of perfecting and consolidating agricultural economic and stable development of industrial economy, the Beibu Gulf shall develop service industry vigorously and further optimize the economic structure. Forth, After successful settlement of the Guangxi FAZ, the Qinzhou Port area can drive foreign trade economy to some extent and stimulate development of logistics service industry and relevant industries indirectly. The importance of FAZ to port logistics lies in its freedom and convenience. Hence, freedom and convenience of ports shall be concerned fully to strengthen logistics competitiveness of ports. In addition, impacts and challenges from other ports will surely intensify the resource competition of port logistics in future. Hence, it has to further improve freedom and convenience of the Beibu Gulf to cope with increasing challenges and threats.

Analysis of the Development Trend in Forensic Odontology Based on CiteSpace.

To realize the dynamic visualization of forensic odontology based on the bibliometrics methods, and capture the research hotspots and identify the future development trend. Literature articles published from January 1995 to December 2020 were searched according to specific subject words in the core data set of Web of Science. The visualization analysis of publishing country, institution, discipline, author, co-cited journal and keywords was performed by CiteSpace 5.7.R5W software. The annual analysis of publications showed an upward trend of forensic odontology research literature year by year, with the number of annual publications more than 110 in the last five years. Developed countries were the main source of contributions and the average centrality was greater than 0.2. The research of forensic odontology involved multiple disciplines, including stomatology, biology, computer science and medical imaging, with a distinct interdisciplinary feature. A total of 115 nodes were obtained by keyword cluster analysis. The principal line of forensic odontology mainly included individual identification and age estimation and the emergence of hotspots was closely related to new technologies. Population-based odontology investigation, improvement of traditional dental age estimation method and dental age estimation based on new technology were popular research in forensic odontology. Developing countries urgently need to increase the focus on related research. It may be an important direction for the development of forensic odontology to establish and enrich the regional dental database, develop new odontology identification technology combined with frontier and high-end technology, and develop the identification program based on advanced information technology.

A novel method to retain a waterproof coal pillar near water-conducting fault

AbstractReducing the width of safe coal pillar near geological structures, such as a water-conducting fault, to improve the extraction ratio of coal seam is a major concern that needs to be addressed urgently for mining shallow coal resources in China. To tackle the contradiction between improving the extraction ratio of resources and the disaster caused by reducing the width of the waterproof coal pillar, this study focuses on retaining the coal (rock) pillar near the water-conducting fault and proposes a novel method for calculating the waterproofing of the coal pillar precisely. We consider the different location relationships between the water-conducting fault, confined aquifer and coal seam, and suggest the principle of retaining the waterproofing of the coal pillar. First, we develop a mechanical model describing a waterproof coal pillar near the water-conducting fault by using elastic–plastic mechanics theory and subsequently calculate the length of plastic zone of the coal pillar under water pressure of the fault by using the limit equilibrium method. Furthermore, we use FLAC3D software to simulate the stress distribution of the coal seam roof and floor under fault water pressure. Subsequently, based on the Mohr–Coulomb strength criterion, we propose a method to calculate the width of waterproof coal pillars by combining the plastic zone with the maximum principal stress propagation line. Ultimately, we assess and discuss the accuracy and simplicity of this method by combining it with engineering methods.

HyMap imagery for copper and manganese prospecting in the east of Ameln valley shear zone (Kerdous inlier, western Anti-Atlas, Morocco)

ABSTRACT Eastern Kerdous demonstrates a polymetallic hydrothermal activity due its association with a paleorelief area. This study focuses on generating a Mineral Potential Map based on Fuzzy Logic Modelling and HyMap-Based input layers. The Relative Absorption Band Depth, Directed Principal Component Analysis, Line Density, and Mixture Tuned Matched Filtering techniques were implemented to perform 20 thematic layers. As a result, three new prospective zones were identified. Fieldwork, petrography, and XRD analysis verified the remote sensing results. Finally, this investigation highlights the significant potential of HyMap imagery for mineral exploration in inaccessible and remote parts of the western Anti-Atlas belt.

Closed-Form Solution of Principal Line for Camera Calibration Based on Orthogonal Vanishing Points

Vanishing point is an important geometric element in sports video. In this paper, a new calibration algorithm is proposed by using the algebraic and geometric properties of vanishing points, which resolves the three main problems of the traditional camera calibration technology based on vanishing points: (1) calibrating camera with varied focal length; (2) screening out outliers from a set of images; (3) estimation of distortion coefficients. The principal line passes through the principal point, and the algebraic relationship between it and the vanishing points is deduced. Using the geometry feature of the principal line, problems (1) and (2) can be easily solved. The linear relationship between the point and the line is used to estimate the distortion coefficient under the condition of obtaining the principal point. Simulation and real experiments show the validity and robustness of the proposed algorithm, and satisfactory results can be obtained by solving the above three problems.

Tracing curvature paths on trimmed multipatch surfaces

Advances in architectural geometry and computation have created strategies to rationalize complex building envelopes. This paper presents techniques to identify paths on freeform surfaces by prescribing specific curvature properties. The paths can be defined by the normal curvature or the geodesic torsion. In special cases, asymptotic and principal curvature lines can be determined. Such paths are used for the design of gridshells with lamellar elements. A brief introduction to differential geometry of freeform surfaces provides the relevant foundations for the method. The relevant quantities and relations are highlighted with illustrations. The consistent description of the paths in the parameter space of the surface avoids unnecessary and complex projection operations. This allows a computationally efficient and robust implementation. The tracing is explained for the simple case of a single surface and extended to trimmed multipatches which are used for geometric modeling in common computer-aided design (CAD) programs. The topological structure of the multipatch was used to trace paths across several surfaces. To enable interactive design, the path tracing techniques were integrated into the parametric CAD package Grasshopper for Rhino. Additional components for curvature analysis were implemented to analyze and evaluate designs. To simplify the handling of curvature lines, a geometry type for embedded curves was introduced and implemented within a CAD environment. Finally, the use of these tools for the design of architecturally sophisticated gridshells is presented along with three projects of increasing complexity.

Differences in Pilon Fractures According to Ipsilateral Fibular Injury Patterns: A Clinical Computed Tomography-Based Mapping Study.

Preoperative verification of fracture morphology is essential for determining the definitive fixation strategy in the management of a pilon fracture. This study aimed to determine the correlation between fibular injury patterns and fracture morphologies and introduce clinical implications. Computed tomography scans of 96 pilon fractures were retrospectively analyzed and divided into three types: intact fibula, simple fracture, and multifragment fracture. The principal fracture line and comminution zones were illustrated on a plafond template and diagrammatized on a 6 × 6 grid using PowerPoint software as fracture mapping. Correlations between fibular injury patterns and fracture morphologies, including comminution zones and principal fracture lines, were analyzed. The thickest comminution zone was most often located in the anterolateral quadrant. According to fibular injury patterns, the comminution zone of the multifragment group was placed two grids more lateral than that of other groups. Lateral exits of the principal fracture line in the multifragment group were much more concentrated within the fibular incisura. In pilon fractures, a more complex fibular fracture pattern was related to the valgus position. Moreover, the articular fracture pattern of pilon fractures differed according to coronal angulation and fibular fracture pattern. These differences should influence the operative approach and placement of the plate.

Analysis of Inheritance patterns, gender dimorphism and their correlation in lip and palm prints - A cross-sectional study.

Forensic sciences deal with key areas to be included in judicial makeup that has been approved by both the court and the scientific community, which distinguishes truth from counterfeit. Lip and palmprints are one of a kind and do not change during the lifetime of a person unless any pathologies. To evaluate the heritability, and gender dimorphism of lip and palm prints among parents and their offspring. A total of 280 participants were included in the study. Lip and palm prints were collected from participants using a digital camera. The photographic data obtained is subjected to Adobe Photoshop and analysed for inheritance. Gender dimorphism is evaluated by the predominant lip pattern and palm ridge count in four designated areas. A positive resemblance of 28.4% was found between parents and offspring in lips, and for the right palm, it was 60.2% and 55.12% for the left palm (principal lines) which are statistically insignificant. In all six quadrants, the most predominant lip pattern found in males is type 5, and in females, type 11. The mean palm ridge density was significantly higher among females than males in all designated areas. The digital method of analysing lip and palm print images with Adobe Photoshop 7 software is a convenient method that allows for better visualisation and easier lip and palm print recording and identification. Considerable inheritance patterns and gender dimorphism were observed that aid in personal identification.

Principal Lines on an Ellipsoid in a Minkowski Three-Dimensional Space

The description of principal lines of the ellipsoid on the 3-dimensional Minkowski space is established. A global principal parametrization of a triple orthogonal system of quadrics is also achieved, and the focal set of the ellipsoid is sketched.