Cloud Contraction Research Articles

Skeleton-based coordinate system construction method for non-cooperative targets

Due to the lack of structure and part information in non-cooperative targets, the task of pose estimation suffers from unstable and unreliable initial coordinate system. In this paper, we introduce a curve-skeleton-based method to construct the robust coordinate system automatically for non-cooperative targets. First, a nonmanifold-Laplacian-based method is proposed to extract the curve skeleton from point clouds. The proposed method solves the over-contraction problem while preserves the topology and structure of skeleton well during point clouds contraction. Additionally, we create the skeleton graph to detect the skeleton structure and key points automatically. Then, the detected skeleton feature is used to construct target coordinate system, and improve the stability and robustness. Specifically, a real-scan dataset is constructed in this paper, and the proposed point cloud contraction method outperforms previous methods in structural representation and visualization. The mean rotation error of proposed coordinate system construct method performs 0.1249° and 1.2135° in 0%–30% noise ratio of distortions and outliers, and performs 7.04° and 4.21° in real-scan aircraft and satellite datasets. The results in complete and incomplete datasets verify the robustness and reliability of our skeleton-based coordinate system.

An exploration of high performance computing cloud contract for SMEs: a systematic literature review

PurposeHigh performance computing (HPC) is used to solve complex calculations that personal computing devices are unable to handle. HPC offers the potential for small- and medium-size enterprises (SMEs) to engage in product innovation, service improvement and the optimization of resource allocation (Borstnar and Ilijas, 2019). However, the expensive infrastructure, maintenance costs and resource knowledge gaps that accompany the use of HPC can make it inaccessible to SMEs. By moving HPC to the cloud, SMEs can gain access to the infrastructure without the requirement of owning or maintaining it, but they will need to accept the terms and conditions of the cloud contract. This paper aims to improve how SMEs access HPC through the cloud by providing insights into the terms and conditions of HPC cloud contracts.Design/methodology/approachThis paper adopts a systematic literature review by implementing a four-step approach. A comprehensive search was undertaken and results synthesized to enable this paper’s objectives to be met.FindingsThis paper proposes that SMEs could gain competitive advantage(s) by understanding their own needs and improving their contract negotiation abilities, service management skills and risk management abilities before accepting the terms and conditions of the cloud contract. Furthermore, a checklist, service-level agreement, easily ignored elements and risk areas are presented as guidance for SMEs when reviewing their HPC cloud contract(s).Originality/valueWhile HPC cloud contracts are a niche research topic, it is one of the key factors influencing the ability of SMEs to access HPC through the cloud. It is, however, by no means a level playfield with SMEs at a distinct disadvantage because of not influencing the writing up of the HPC cloud contract. The added value of the paper is that it contributes to our overall understanding of the terms and conditions of HPC cloud contracts.

The Public Sector Cloud Service Procurement in Sweden

This paper investigates the use of cloud services in the public sector and management of information security challenges in the procurement of such services. The findings are based on an exploratory approach that included a systematic literature review and a survey among the public agencies and municipalities in Sweden. The literature review is used to derive a conceptual framework that structures our empirical results into the three groups: a) contractual and legal, b) operational and c) managerial competency. The survey explored all these three groups. Our findings show that the information security challenges are mostly related to the potential breaching of national security and laws applicable to cross-border cloud services. Most of the cloud contracts of public organizations are found to be supplier driven. In this case, lack of knowledge and awareness in managing procurement are mostly raised compared to technical risks.

Star Formation Triggered by Shocks

Abstract Star formation can be triggered by compression from shock waves. In this study, we investigated the interaction of hydrodynamic shocks with Bonnor–Ebert spheres using 3D hydrodynamical simulations with self-gravity. Our simulations indicated that the cloud evolution primarily depends on two parameters: shock speed and initial cloud radius. Stronger shocks can compress clouds more efficiently, and when the central region becomes gravitationally unstable, a shock triggers cloud contraction. However, if it is excessively strong, it shreds the cloud more violently and the cloud is destroyed. From simple theoretical considerations, we derived the condition of triggered gravitational collapse, which agreed with the simulation results. Introducing sink particles, we followed the further evolution after star formation. Since stronger shocks tend to shred the cloud material more efficiently, the stronger the shock is, the smaller the final (asymptotic) masses of the stars formed (i.e., sink particles) become. In addition, shocks accelerate clouds, promoting mixing of shock-accelerated interstellar medium gas. As a result, the separation between sink particles and shocked clouds center and their relative speeds increase over time. We also investigated the effect of cloud turbulence on shock–cloud interaction. We observed that cloud turbulence prevents rapid cloud contraction; thus, turbulent clouds are destroyed more rapidly than thermally supported clouds. Therefore, the masses of stars formed become smaller. Our simulations provide a general guide to the evolutionary process of dense cores and Bok globules impacted by shocks.

Chemical analysis of prestellar cores in Ophiuchus yields short timescales and rapid collapse

Sun-like stars form from the contraction of cold and dense interstellar clouds. How the collapse proceeds and what the main physical processes are driving it, however, is still under debate and a final consensus on the timescale of the process has not been reached. If the contraction proceeds slowly, supported by strong magnetic fields and mediated by ambipolar diffusion, or is driven by fast collapse with gravity dominating the entire process is still an open question. One way to answer this question is to measure the age of prestellar cores through statistical methods based on observations or via reliable chemical chronometers, which should better reflect the physical conditions of the cores. Here we report Atacama Pathfinder EXperiment observations of ortho-H2D+ and para-D2H+ for six cores in the Ophiuchus complex, and we combined them with detailed three-dimensional magneto-hydrodynamical simulations including chemistry, providing a range of ages for the observed cores of up to 200 kyr. The outcome of our simulations and subsequent analysis provides a good matching with the observational results in terms of physical parameters (core masses and volume densities) and dynamical parameters such as the Mach number and the virial parameter. We show that models of fast collapse successfully reproduce the observed range of chemical abundance ratios since the timescales to reach the observed stages is comparable to the dynamical time of the cores (i.e. the free-fall time) and much shorter than the ambipolar diffusion time, measured from the electron fraction in the simulations. To confirm that this ratio can be used to distinguish between different star-formation scenarios, a larger (statistically relevant) sample of star-forming cores should be explored.

Budget optimized dynamic virtual machine provisioning in hybrid cloud using fuzzy analytic hierarchy process

Among various deployment models, Hybrid cloud is the preferred model allowing customers to maximize cost savings and performance by leveraging advantage of quick provisioning capabilities of public cloud. However, due to vast diversity of cloud services, today’s struggle for the customers is to evaluate and discover the best fit Cloud Service Provider (CSP) for an efficient Virtual Machine (VM) provisioning in various hybrid cloud contracts of multi cloud environment. Currently there is no framework that allows customers to evaluate CSPs based on application workload, application environment and employ an budget optimized VM provisioning with dynamically varying factors while adhering to Service Level Agreement (SLA). Hence, the proposed VM Provisioning framework is a Multi Criteria Decision-Making (MCDM) model with an objective to provision the VMs from the well suited CSP in hybrid cloud. The framework initially derives weights for each decision-making input criteria considered as Quality of Service (QoS) Service Measurement Index (SMI) attributes using extent analysis method of Fuzzy Analytical processing (FHP). It ranks the CSP by aggregating weights of decision makers among the alternatives. The framework then proposes a budget optimized algorithm called BOPVM to provision VMs in the hybrid cloud based on the order of assigned rank to CSPs. The framework is evaluated and implemented on real time workload among the CSPs – Amazon, Azure and Openstack. The evaluation results shows significant provisioning cost savings of 50% with reduced provisioning time by 65% when compared with existing algorithms.

Cybersecurity in outsourcing and cloud computing: a\xa0growing challenge for contract drafting

With increasing regulation of IT security, the relevance of contract drafting also increases. Outsourcing and cloud contracts must strike the right balance between customer-specific IT security requirements and established service provider standards.

Hybrid Cloud SLAs for Industry 4.0: Bridging the Gap

Hybrid Cloud Service Level Agreements (SLA) comprises of the legal terms and conditions for the cloud contract. Even though all the service level objectives, metrics and service descriptions are clearly outlined in the cloud SLA contract, sometimes vendors fail to meet the promised services and confusing terms lead to tenant-vendor cloud legal battles. Hybrid Cloud involves two different cloud models (public and private) working together, applications running under the hybrid cloud are subject to different availability sets, functionality and parameters developing SLA complexity and ambiguity. The new manufacturing environment (Industry 4.0 concept) is based on a fully connected, intelligent and automated factory, which will highly be dependent on cloud computing and IoT-based solutions for data analytics, storage and computational needs. In situations where Hybrid cloud services are not defined and managed properly may result in Industrial-IoT data security issues leading to financial and data losses. This paper discusses various aspects of the cloud service level agreement in Industry 4.0 for better understanding and implementation and puts a light on the issues that arise out of imprecise statements.

Survey of ortho-H2D+ in high-mass star-forming regions

Context. Deuteration has been suggested to be a reliable chemical clock of star-forming regions due to its strong dependence on density and temperature changes during cloud contraction. In particular, the H3+ isotopologues (e.g. ortho-H2D+) seem to act as good proxies of the evolutionary stages of the star formation process. While this has been widely explored in low-mass star-forming regions, in the high-mass counterparts only a few studies have been pursued, and the reliability of deuteration as a chemical clock remains inconclusive. Aims. We present a large sample of o-H2D+ observations in high-mass star-forming regions and discuss possible empirical correlations with relevant physical quantities to assess its role as a chronometer of star-forming regions through different evolutionary stages. Methods. APEX observations of the ground-state transition of o-H2D+ were analysed in a large sample of high-mass clumps selected from the ATLASGAL survey at different evolutionary stages. Column densities and beam-averaged abundances of o-H2D+ with respect to H2, X(o-H2D+), were obtained by modelling the spectra under the assumption of local thermodynamic equilibrium. Results. We detect 16 sources in o-H2D+ and find clear correlations between X(o-H2D+) and the clump bolometric luminosity and the dust temperature, while only a mild correlation is found with the CO-depletion factor. In addition, we see a clear correlation with the luminosity-to-mass ratio, which is known to trace the evolution of the star formation process. This would indicate that the deuterated forms of H3+ are more abundant in the very early stages of the star formation process and that deuteration is influenced by the time evolution of the clumps. In this respect, our findings would suggest that the X(o-H2D+) abundance is mainly affected by the thermal changes rather than density changes in the gas. We have employed these findings together with observations of H13CO+, DCO+, and C17O to provide an estimate of the cosmic-ray ionisation rate in a sub-sample of eight clumps based on recent analytical work. Conclusions. Our study presents the largest sample of o-H2D+ in star-forming regions to date. The results confirm that the deuteration process is strongly affected by temperature and suggests that o-H2D+ can be considered a reliable chemical clock during the star formation processes, as proved by its strong temporal dependence.

PointSkelCNN: Deep Learning‐Based 3D Human Skeleton Extraction from Point Clouds

AbstractA 3D human skeleton plays important roles in human shape reconstruction and human animation. Remarkable advances have been achieved recently in 3D human skeleton estimation from color and depth images via a powerful deep convolutional neural network. However, applying deep learning frameworks to 3D human skeleton extraction from point clouds remains challenging because of the sparsity of point clouds and the high nonlinearity of human skeleton regression. In this study, we develop a deep learning‐based approach for 3D human skeleton extraction from point clouds. We convert 3D human skeleton extraction into offset vector regression and human body segmentation via deep learning‐based point cloud contraction. Furthermore, a disambiguation strategy is adopted to improve the robustness of joint points regression. Experiments on the public human pose dataset UBC3V and the human point cloud skeleton dataset 3DHumanSkeleton compiled by the authors show that the proposed approach outperforms the state‐of‐the‐art methods.

Intensity Change of Typhoon Nancy (1961) during Landfall in a Moist Environment over Japan: A Numerical Simulation with Spectral Nudging

Abstract Intensity change of tropical cyclones (TCs) as they make landfall is closely linked to sustained periods of high surface winds and heavy precipitation. Few studies have investigated the intensity change of intense TCs that make landfall in middle latitudes such as Japan because few intense typhoons make landfall in middle latitudes. In this study, a numerical simulation of intense Typhoon Nancy (1961) was used to understand the intensity change that occurred when Nancy made landfall in Japan. A spectral nudging technique was introduced to reduce track errors in the simulation. During landfall, the simulated storm exhibited the salient asymmetric structure and rapid eyewall contraction. A tangential wind budget indicated that the maximum wind speed decreased concurrent with an increase in surface friction and advection associated with low-level asymmetric flows. Detailed evolution of the storm’s warm core was analyzed with a potential temperature budget. In the upper part of the warm core centered at a 12-km height, cooling due to ventilation by asymmetric flows and longwave radiation overcame heating due to condensation and shortwave radiation during the contraction of eyewall clouds. In the lower part of the warm core, adiabatic cooling more than offset warm-air intrusions associated with asymmetric flows and condensational heating. The condensation was supplied by an abundance of moisture due to evaporation from the ocean in the well-developed typhoon based on a moisture budget. Sensitivity experiments revealed that environmental baroclinicity in the midlatitudes, orography, and radiative processes made minor contributions to the weakening. The weakening was instead controlled by inner-core dynamics and interactions with land surfaces.

Multiwavelength Polarimetry of the Filamentary Cloud IC 5146. II. Magnetic Field Structures

Abstract The IC 5146 cloud is a nearby star-forming region in Cygnus, consisting of molecular gas filaments in a variety of evolutionary stages. We used optical and near-infrared polarization data toward the IC 5146 cloud, reported in the first paper of this series, to reveal the magnetic fields in this cloud. Using the newly released Gaia data, we found that the IC 5146 cloud may contain two separate clouds: a first cloud, including the densest main filament at a distance of ∼600 pc, and a second cloud, associated with the Cocoon Nebula at a distance of ∼800 pc. The spatially averaged H-band polarization map revealed a well-ordered magnetic field morphology, with the polarization segments perpendicular to the main filament but parallel to the nearby subfilaments, consistent with models assuming that the magnetic field is regulating cloud evolution. We estimated the magnetic field strength using the Davis–Chandrasekhar–Fermi method and found that the magnetic field strength scales with volume density with a power-law index of ∼0.5 in the density range from to 3000 cm−3, which indicates an anisotropic cloud contraction with a preferred direction along the magnetic field. In addition, the mass-to-flux ratio of the cloud gradually changes from subcritical to supercritical from the cloud envelope to the deep regions. These features are consistent with strong magnetic field star formation models and suggest that the magnetic field is important in regulating the evolution of the IC 5146 cloud.

Research on geometric features and point cloud properties for tree skeleton extraction

To solve skeleton extraction problems in the tree point cloud model, branch geometric features and local properties of point cloud are utilized to optimize tree skeleton extraction. First of all, according to the attribute information estimation and normal vector adjustment of point cloud neighbor domain, branch segmentation is made by estimated values and geometric features. Skeleton nodes are extracted in the branch subset in segmentations. Then, a graph is constructed based on skeleton node set and tree skeleton is reconstructed in this weighted directed graph. Finally, according to the tree growth characteristics, cubic Hermite curves are utilized to optimize the skeleton curve. This method is applied in the point cloud model of three-kind trees and it is compared with the skeleton extraction method based on voxel switch and point cloud contraction. The experiment results show that this method displays strong anti-interference and high-precision characteristics at branch bifurcation and crossed ending parts of fine tree branches. Thus, features of tree branches can be described more perfectly, obtaining the skeleton curve closer to the main axis.

Hierarchical structure of the interstellar molecular clouds and star formation

Abstract Properties of the hierarchical structures of interstellar molecular clouds are discussed. Particular attention is paid to the statistical correlations between velocity dispersion and size, and between the magnetic field strength and gas density. We investigate the formation of some hierarchical structures with the help of numerical MHD simulations using the ENLIL code. The simulations show that the interstellar molecular filaments with parallel magnetic field and molecular cores can form via the collapse and fragmentation of cylindrical molecular clouds. The parallelmagnetic field halts the radial collapse of the cylindrical cloud maintaining its nearly constant radius ~0.1 pc. The observed filaments with perpendicularmagnetic field can form as a result of themagnetostatic contraction of oblate molecular clouds under the action of Alfvén and MHD turbulence. The theoretical density profiles are fitted with the Plummer-like function and agree with observed profiles of the filaments in Gould’s Belt. The characteristics of molecular cloud cores found in our simulations are in agreement with observations.

Trends of Stellar Evolution in Modern Physics

In this paper, it examines the trends of stellar evolution reflected in modern physics, identifying the uncertainties present in the established schemes. It explains that during spontaneous contraction of gas clouds the process of heating up cannot be replaced by cooling without qualitative changes in the structure of the clouds. It is shown that the luminous objects can be resistant to decay due to the gravitational interactions, even at low mass; that the outcome of stellar evolution does not yet have a clear description; that spontaneous gravitational contraction of gas clouds in space is largely concluded by the formation of structures resistant to gravitational forces. The recognition of structures resistant to the forces of gravity is a very important element of understanding, which will help in future theoretical research.

Understanding the Links among the Magnetic Fields, Filament, Bipolar Bubble, and Star Formation in RCW 57A Using NIR Polarimetry

Abstract The influence of magnetic fields (B-fields) on the formation and evolution of bipolar bubbles, due to the expanding ionization fronts (I-fronts) driven by the H ii regions that are formed and embedded in filamentary molecular clouds, has not been well-studied yet. In addition to the anisotropic expansion of I-fronts into a filament, B-fields are expected to introduce an additional anisotropic pressure, which might favor the expansion and propagation of I-fronts forming a bipolar bubble. We present results based on near-infrared polarimetric observations toward the central ∼8′ × 8′ area of the star-forming region RCW 57A, which hosts an H ii region, a filament, and a bipolar bubble. Polarization measurements of 178 reddened background stars, out of the 919 detected sources in the JHK s bands, reveal B-fields that thread perpendicularly to the filament long axis. The B-fields exhibit an hourglass morphology that closely follows the structure of the bipolar bubble. The mean B-field strength, estimated using the Chandrasekhar–Fermi method (CF method), is 91 ± 8 μG. B-field pressure dominates over turbulent and thermal pressures. Thermal pressure might act in the same orientation as the B-fields to accelerate the expansion of those I-fronts. The observed morphological correspondence among the B-fields, filament, and bipolar bubble demonstrate that the B-fields are important to the cloud contraction that formed the filament, to the gravitational collapse and star formation in it, and in feedback processes. The last one includes the formation and evolution of mid-infrared bubbles by means of B-field supported propagation and expansion of I-fronts. These may shed light on preexisting conditions favoring the formation of the massive stellar cluster in RCW 57A.

DEBESŲ SUTARČIŲ KVALIFIKAVIMAS

Debesų sutarčių teisinis kvalifikavimas vis dažniau tampa įvairių studijų, mokslinių tyrimų ar teisėkūros iniciatyvų vienu iš nagrinėtinų klausimų. Atsižvelgiant į debesų sutarties tipą, kartais debesų sutartį siūloma kvalifikuoti kaip nuomos, kitais atvejais kaip paslaugų sutartį. Debesų paslaugų teikėjai savo teikiamą paslaugą įvardija ir kaip licencijos suteikimą. Šiame straipsnyje siekiama įvertinti siūlymus dėl debesų sutarčių kvalifikavimo, pirmiausia, apibūdinant debesų sutarčių požymius, ir analizuojant jų atitiktį tam tikrų įstatymų reglamentuotų rūšių sutarčių kvalifikuojantiems požymiams.

A robust 3D point cloud skeleton extraction method

A robust method for three-dimensional point cloud skeleton extraction is proposed in this paper. First, a Laplace operator is used for contracting three-dimensional point cloud locally, and PCA (principal component analysis) is performed on the contracted point cloud to extract skeleton branches. Then, the local points that have been extracted as skeleton branches are fixed while the rest undergo further contraction. Point cloud contraction and local skeleton extraction are repeated until a complete skeleton curve that satisfies the termination conditions is obtained. Finally, by processing the cross points of skeleton and fitting cubic B-spline curves onto them, we can obtain the final skeleton curves. Experimental results show that, compared to existing methods, point cloud skeleton extraction with the proposed method is more robust and resistant to noise.

Chemical differentiation in a prestellar core traces non-uniform illumination

Dense cloud cores present chemical differentiation due to the different distribution of C-bearing and N-bearing molecules, the latter being less affected by freeze-out onto dust grains. In this letter we show that two C-bearing molecules, CH$_3$OH and $c$-C$_3$H$_2$, present a strikingly different (complementary) morphology while showing the same kinematics toward the prestellar core L1544. After comparing their distribution with large scale H$_2$ column density N(H$_2$) map from the Herschel satellite, we find that these two molecules trace different environmental conditions in the surrounding of L1544: the $c$-C$_3$H$_2$ distribution peaks close to the southern part of the core, where the surrounding molecular cloud has a N(H$_2$) sharp edge, while CH$_3$OH mainly traces the northern part of the core, where N(H$_2$) presents a shallower tail. We conclude that this is evidence of chemical differentiation driven by different amount of illumination from the interstellar radiation field: in the South, photochemistry maintains more C atoms in the gas phase allowing carbon chain (such as $c$-C$_3$H$_2$) production; in the North, C is mainly locked in CO and methanol traces the zone where CO starts to freeze out significantly. During the process of cloud contraction, different gas and ice compositions are thus expected to mix toward the central regions of the core, where a potential Solar-type system will form. An alternative view on carbon-chain chemistry in star-forming regions is also provided.

Governmental Cloud - Part of Cloud Computing

Large IT (Information Technology) companies propose cloud government's (G-Cloud) development model through investment from the private sector, which will facilitate the access of users from public sector to the new generation IT services. Through the G-Cloud private operators that operate governmental cloud infrastructure by adding specific SaaS (Software as a Service) functionalities, proposed model by big companies, supports public institutions in optimizing costs and increased operational efficiency, bringing tangible benefits in relation with citizens and thus with the whole society. These optimizations are achieved by moving the initial investment to the private sector, through type subscription model cost by eliminating dependency on human factors (technical) and by providing a low cost [1]. This paper aims to bring to the attention of specialists, some aspects of Governmental Cloud from the European Union (EU) countries to be understood and implemented in Romania.Keywords: Cloud Computing, Governmental Cloud, Big Data Analytics1 IntroductionGovernment Cloud is a concept already introduced in other European countries such as Great Britain (under the name of G-Cloud), providing quality public services and much more easily accessible to citizens. Large IT companies bring on the Romanian market the technology and the expertise to provide innovative solutions for the public cloud sector.Creating an integrated and unified government cloud market, assumes the emergence of private operators to manage the access to cloud solutions and which operate in an efficient infrastructure of public institutions. Through collaboration, major IT companies intend to facilitate the access and the use of integrated IT solutions at the national level, in cloud, with minimal investment from the state budget [2].2 Cloud in the European Union2.1 A short history of cloud in the EUIn September 2012, the European Commission (EC) adopted a strategy for Unlocking the potential of cloud in Europe [3]. The strategy aims to encourage the use of cloud in all sectors of the EU economy and the group of experts is a key element in this strategy and the Commission's efforts to encourage further development of the unique digital market.The strategy is based on other legislative initiatives, such as EU reform of data protection [4] and the optional European legislation proposal in sales area [5]. Expert Group helps the Commission to examine how to improve the legal framework for cloud contracts for consumers and SME's [6], in order to strengthen the confidence of consumers and SMEs on the usage of cloud contracts.Cloud computing concept describes the procedure for storing data (such as text files, pictures and videos) and the use of software on remote computers accessed by users, through the internet , using any device they want. This method is faster, cheaper, and more flexible and potentially more secured than local IT solutions.Many services such as Tace hook, Spotify and web-based email, use cloud technologies, but the real economic benefits are obtained only when these cloud solutions are widely adopted by companies and public sector organizations.2.2 EC Strategy in cloud domainThe Commission's strategy on cloud includes three key actions, one of these aiming to identify secure and fair contractual terms and conditions for cloud contracts. The existence of standard contractual clauses can contribute to the facilitation of contractual agreements between service providers and cloud consumers or small businesses. These can also facilitate the application of the EU rules data protection, to the extent that respective terms are relevant to the cloud contracts. European Commission's proposals for reforming the data protection, which received an overwhelming majority of votes in the European Parliament [4], will introduce also a framework that will contribute and encourage the development of cloud services. …