Static Configuration Research Articles

Experimental Study of the Dynamic Performance of Steel Catenary Riser within the Touchdown Zone

This study proposed a novel experimental platform to conduct dynamic loading tests of a truncated model steel catenary riser (SCR) within the touchdown zone (TDZ). The facilities of the platform, including a soil tank, a loading system, and a soil stirring system, were introduced in detail. The parameters of the test were determined through the simulation of an in situ riser. A steel pipe was adopted as the model riser, with its outer diameter equaling that of the prototype SCR. Before executing the dynamic loadings, the model riser developed its static configuration under the submerged weight and applied bending moment. Subsequently, cyclic vertical and lateral displacement loads were applied to the truncated point. The test results showed that when the vertical loading amplitude increased from 200 mm to 300 mm, the stress ranges at the front of the model riser increased by more than 100%, whereas the stress range only differed by less than 5% under different loading periods. Numerical models of the SCR were built based on the vector form intrinsic finite element (VFIFE) method. High similarities between the test and simulation results proved the reliability of the nonlinear soil model and the numerical model. During the test, a seabed trench was developed with a depth of 0.71 D and a width of 0.48 D, and its shape was similar to the in situ trench.

Low delay network attributes randomization to proactively mitigate reconnaissance attacks in industrial control systems

Industrial Control Systems are used in a wide variety of industrial facilities, including critical infrastructures, becoming the main target of multiple security attacks. A malicious and successful attack against these infrastructures could cause serious economic and environmental consequences, including the loss of human lives. Static networks configurations and topologies, which characterize Industrial Control Systems, represent an advantage for attackers, allowing them to scan for vulnerable devices or services before carrying out the attack. Identifying active devices and services is often the first step for many attacks. This paper presents a proactive network reconnaissance defense mechanism based on the temporal randomization of network IP addresses, MAC addresses and port numbers. The obtained information distortion minimizes the knowledge acquired by the attackers, hindering any attack that relies on network addressing. The temporal randomization of network attributes is performed in an adaptive way, minimizing the overhead introduced in the network and avoiding any error and latency in communications. The implementation as well as the tests have been carried out in a laboratory with real industrial equipment, demonstrating the effectiveness of the presented solution.

Understanding creep suppression mechanisms in polymer nanocomposites through machine learning.

While recent efforts have shown how local structure plays an essential role in the dynamic heterogeneity of homogeneous glass-forming materials, systems containing interfaces such as thin films or composite materials remain poorly understood. It is known that interfaces perturb the molecular packing nearby, however, numerous studies show the dynamics are modified over a much larger range. Here, we examine the dynamics in polymer nanocomposites (PNCs) using a combination of simulations and experiments and quantitatively separate the role of polymer packing from other effects on the dynamics, as a function of distance from the nanoparticle surfaces. After showing good qualitative agreement between the simulations and experiments in glassy structure and creep compliance, we use a machine-learned structure indicator, softness, to decompose polymer dynamics in our simulated PNCs into structure-dependent and structure-independent processes. With this decomposition, the free energy barrier for polymer rearrangement can be described as a combination of packing-dependent and packing-independent barriers. We find both barriers are higher near nanoparticles and decrease with applied stress, quantitatively demonstrating that the slow interfacial dynamics is not solely due to polymer packing differences, but also the change of structure-dynamics relationships. Finally, we present how this decomposition can be used to accurately predict strain-time creep curves for PNCs from their static configuration, providing additional insights into the effects of polymer-nanoparticle interfaces on creep suppression in PNCs.

Comparison of Acoustofluidic and Static Systems for Ultrasound-Mediated Molecular Delivery to T Lymphocytes.

Continuous-flow acoustofluidic technologies can potentially improve processing of T lymphocytes for cell therapies by addressing the limitations with viral and non-viral delivery methods. The objective of this study was to assess the intracellular delivery efficiency with acoustofluidic treatment compared with that of static ultrasound treatment. Optimization of parameters in acoustofluidic and static configurations was performed by assessing intracellular delivery of a fluorescent compound (calcein) in viable human Jurkat T lymphocytes. Ultrasound pressure and the concentration of cationic phospholipid-coated microbubbles influenced calcein delivery in both systems. In the static system, a treatment time of 45 s increased molecular delivery compared with 0-30 s (p < 0.01). Refined parameters were used to assess molecular delivery of small and large compounds (0.6-kDa calcein and 150-kDa fluorescein isothiocyanate-dextran, respectively) after ultrasound treatment with the acoustofluidic or static systems. Molecular delivery was similar with refined parameters for acoustofluidic treatment and static treatment (p > 0.05), even though acoustofluidic treatment had lower microbubble concentration (24 μg/mL vs. 94 μg/mL) and shorter treatment time (∼2-3 s vs. 45 s). This study indicates that the acoustofluidic system can significantly enhance intracellular molecular delivery, which could potentially enable acoustofluidic cell transfection during continuous flow processing for manufacture of cell therapies or other applications.

Radiation of higher order modes from circular ducts with flow

This work aims to predict the transfer function of a given modal content inside a circular duct with a bellmouth inlet in the presence of a mean flow. The transfer function is the relation in amplitude and phase between a given mode inside the duct and an observer located in the far-field. The numerical solution is obtained by finite element simulation in which the mean flow is input data. Verification is provided by comparison to the analytical solution of an unbaffled circular duct with uniform flow. Influence from various parameters such as the geometry and mean Mach number on the radiated pressure field is investigated. The analytical solution is a good approximation for finding the radiated principal lobe, and the inlet geometry is found to be more important than other parameters such as mean flow when static inlet configuration is studied.

Performance Evaluation of Static PV Array Configurations for Mitigating Mismatch Losses

Performance Evaluation of Static PV Array Configurations for Mitigating Mismatch Losses

Fourier-Limited Attosecond Pulse from High Harmonic Generation Assisted by Ultrafast Magnetic Fields

One of the main constraints for reducing the temporal duration of attosecond pulses is the attochirp inherent to the process of high-order harmonic generation (HHG). Though the attochirp can be compensated in the extreme-ultraviolet using dispersive materials, this is unfeasible toward x-rays, where the shortest attosecond or even sub-attosecond pulses could be obtained. We theoretically demonstrate that HHG driven by a circularly polarized infrared pulse while assisted by an strong oscillating ultrafast intense magnetic field enables the generation of few-cycle Fourier-limited few attosecond pulses. In such a novel scenario, the magnetic field transversally confines the ionized electron during the HHG process, analogously to a nanowire trapping. Once the electron is ionized, the transverse electron dynamics is excited by the magnetic field, acting as a high-energy reservoir to be released in the form of phase-locked spectrally wide high-frequency harmonic radiation during the electron recollision with the parent ion. In addition, the transverse breathing dynamics of the electron wavepacket, introduced by the magnetic trapping, strongly modulates the recollision efficiency of the electronic trajectories, thus the attosecond pulse emissions. The aftermath is the possibility of producing high-frequency (hundreds of eV) attosecond isolated few-cycle pulses, almost Fourier limited. The isolated intense magnetic fields considered in our simulations, of tens of kT, can be produced in finite spatial volumes considering structured beams or stationary configurations of counter-propagating state-of-the-art multi-terawatt/petawatt lasers.

Negative Pell Equation and Stationary Configurations of Point Vortices on the Plane

Работа посвящена изучению модели точечных вихрей, предложенной немецким ученым Германом Гельмгольцем. Найдены необходимые и достаточные условия существования бесконечного числа неэквивалентных статических конфигураций для системы, состоящей из двух точечных вихрей интенсивности $\Gamma_1$ и произвольного числа точечных вихрей интенсивности $\Gamma_2$. Проведена классификация таких конфигураций. Впервые обнаружена связь между отрицательным диофантовым уравнением Пелля и статическими конфигурациями точечных вихрей на плоскости. Библиография: 20 названий.

An Introduction to the Application of Marine Controlled-Source Electromagnetic Methods for Natural Gas Hydrate Exploration

Natural gas hydrates have been an unconventional source of energy since the beginning of this century. Gas-hydrate-filled reservoirs show higher resistivity values compared with water-filled sediments. Their presence can be detected using marine controlled-source electromagnetic methods. We classify acquisition configurations into stationary and moving receiver configurations, which are described in terms of the design group, the operational details, and where they have been used successfully in the field for natural gas hydrate exploration. All configurations showed good numerical results for the detection of a 700 m long gas hydrate reservoir buried 200 m below the seafloor, but only the stationary configurations provided data that can be used to estimate the horizontal boundaries of the resistive part of the reservoir when the burial depth is known from seismic data. We discuss the operational steps of the configurations and provide the steps on how to choose a suitable configuration. Different CSEM configurations were used together with seismic data to estimate the edge of the gas hydrate reservoir and the total volume of the gas hydrates, to optimize the drilling location, to increase production safety, and to improve geological interpretations. It seems that CSEM has become a reliable method to aid in the decision-making process for gas hydrate reservoir appraisal and development.

Rapidly rotating neutron stars with realistic nuclear matter equation of state

AbstractWe performed the comparison of three different numerical codes for constructing equilibrium models; (I) a code for static equilibrium configurations, (II) an implementation of the Hartle–Thorne slow‐rotation approximation, (III) a numerical solution of the full Einstein equations by LORENE. We aimed to construct sequences of uniformly rotating configurations at various rotation frequencies up to the Keplerian frequency for a hybrid hadronic–quark matter EOS where a smooth transition is provided between two separate phases. We investigated the difference between the results computed by the implementation of Hartle–Thorne slow‐rotation approximation and by LORENE/nrotstar, respectively. We have concluded that the codes can increase the difference between the slow‐rotating and the fast‐rotating approach exponentially, reaching 6.67% for the maximal mass configuration rotating at the Keplerian frequency.

USING THE GREEN – RVACHEV’S QUASIFUNCTIONS METHOD IN THE NUMERICAL ANALYSIS OF ONE ELECTROSTATIC NANOELECTROMECHANICAL SYSTEM

The problem of numerical analysis of one electrostatic nanoelectromechanical system is considered in the article. Nanoelectromechanical systems are miniature devices that combine electronic and mechanical components of micro and nano sizes. Electrostatic actuation of the mechanical components of such systems is one of the most common types of actuation and that used in accelerometers, switches, micro-mirrors, micro-resonators, etc. The disadvantages of such devices are related to the pull-in instability. This effect occurs when the voltage applied to the moving electrode exceeds a critical value, causing the system to lose its stationary configuration. A semi-linear elliptic equation with the Laplace operator and the first boundary condition was used for mathematical modeling of the process. To construct an approximate solution of the problem, it is suggested to use the methods of nonlinear analysis in semi-ordered spaces, in particular, the results of V. I. Opoitsev on the solvability of nonlinear operator equations with a heterotone operator. The boundary value problem modeling the nanoelectromechanical system is reduced to the integral Urysohn’s equation using the Green – Rvachev’s quasi-function method, which allows us to expand the application of the two-sided approximation method for domains of fairly arbitrary geometry. The article substantiates the possibility of constructing two-sided approximations to a positive solution of the problem, namely: a computational scheme is given, conditions for its convergence to a single positive solution of the problem under consideration are obtained, and an error estimate is obtained. The method is illustrated by computational experiments for a problem considered in a rectangular domain. The results of computational experiments are presented in the form of numerical and graphical information.

Research on Design Method of Security Test Set Based on AUTOSAR OS

In recent years, the automobile industry have shown the de-velopment trend of intelligence and networking. OSEK OS, the kind of traditional vehicle control operating system, has the characteristics of static configuration, but it cannot support new industry demands such as ADAS and OTA. Automobiles have become an important part of smart cities, and are currently developing in the direction of intelligence, networking, openness and sharing. However, OSEK OS, the traditional vehicle control operating system, statically configures tasks, alarms and other modules before running, which cannot be changed at runtime. Therefore, it is difficult to meet the needs of intelligent networked vehicles. AUTOSAR OS, the next-generation vehicle control operating system, adds sev-eral new functional modules and security mechanisms and is totally compatible with OSEK OS. In order to verify the re-liability of the new functional modules and security mecha-nisms of AUTOSAR OS, we tests the security mechanisms of VKware OS, which is an open source AUTOSAR OS, and designs a test set that conforms to the specification of AU-TOSAR OS, the test case can also be used for functional and security mechanism test of various AUTOSAR OS.

Analysis of hyperbolically symmetric fluid configurations in modified Gauss–Bonnet gravity

This paper studies in detail the general physical properties inherent to the static fluid configurations possessing hyperbolic symmetry through the mechanism of modified Gauss–Bonnet gravity (GBG). The energy density of the anisotropic fluid configuration seems to be essentially negative, which indicates that any possible application of these fluid distributions needs severe physical constraints wherein quantum processes become significant. Several exact hyperbolically symmetric solutions with their corresponding generating functions are presented by imposing certain conditions (i.e., conformal flatness, vanishing complexity factor and stiff equation of state) on the fluid variables in the presence of higher-curvature GBG-corrections. Few of the provided stellar solutions exhibit the evolution of hyperbolically symmetric matter configurations whose center of symmetry is surrounded by a vacuum cavity.

Study of Anisotropic Fluid Distributed Hyperbolically in f(R,T,Q) Gravity

The core of this manuscript is to conduct a broad investigation into the features of static matter configurations with hyperbolical symmetry, which might possibly serve as formation of corresponding spacetime within the limits of f(R,T,Q) gravity, where (Q ≡ RασTασ). We recognize that such matter distributions can be anisotropic in pressure, with just two primary stresses unequal and a negative energy density. Usually, negative matter densities are suggested in extreme cosmological and astrophysical situations, particularly with regard to quantum occurrences that might occur within the horizon. Eventually, we construct a generic formalism that allows every static hyperbolically symmetric (HS) fluid solution to be expressed with respect to two generating functions (GFs).

Continuous Gravitational Wave Emissions from Neutron Stars with Pinned Superfluids in the Core

We investigate the effect of a pinned superfluid component on the gravitational wave emissions of a rotating neutron star. The pinning of superfluid vortices to the flux-tubes in the outer core (where the protons are likely to form a type-II superconductor) is a possible mechanism to sustain long-lived and non-axisymmetric neutron currents in the interior, which break the axial symmetry of the unperturbed hydrostatic configuration. We consider pinning-induced perturbations to a stationary corotating configuration and determine the upper limits on the strength of gravitational wave emissions due to the pinning of vortices with a strong toroidal magnetic field of the kind predicted by recent magneto-hydrodynamic simulations of neutron star interiors. We estimate the contributions to gravitational wave emissions from both the mass and current multipole generated by the pinned vorticity in the outer core and find that the mass quadrupole can be large enough for gravitational waves to provide the dominant spindown torque in millisecond pulsars.

Development of a Time-Domain Simulation Code for Cross-Flow Vortex-Induced Vibrations of a Slender Structure with Current Using the Synchronization Model

In this paper, the numerical analysis method for the cross-flow vortex-induced vibration (CF VIV) analysis based on the proposed procedure for CF VIV analysis of slender structures is developed. In order to consider the changes in the incoming flow according to the static configuration of the slender structures due to the current, the proposed procedure has three stages. A slender structure is modeled as the lumped-mass line, and the dynamic relaxation method known as the numerical technique for a slender structure with large geometric nonlinearity is applied in the static analysis. The comparison studies with a commercial program are carried out to validate the developed code. The vortex-induced force on slender structures is considered with the synchronization model. To verify the developed CF VIV analysis procedure and numerical method for a slender structure, VIV analysis of the tensioned flexible risers under a uniform and shear current is performed. The simulated results of CF RMS displacement show good agreement with the results of the model test It is found that a tensioned riser vibrates with one dominant frequency in resonance with the nth mode, even though multi-frequencies components of the vortex shedding along the riser due to the shear current occurs.

A Quantification Method for the Heterogeneity of Mimic Control Plane in SDN

SDN (Software-Defined Networking) renders network management more centralized and flexible. However, its control plane is vulnerable to attacks. By introducing dynamic heterogeneous redundancy, the amimic control plane is built to effectively solve the problems of single control points of failure, unknown backdoor vulnerabilities and static configuration. Heterogeneity is an important indicator for evaluating the security of a system. Generally speaking, the greater the heterogeneity, the higher the security. Currently, there is little research evaluating the security of the mimic control plane in SDN by quantifying the heterogeneity. To this end, this paper proposes two methods for measuring the heterogeneity, based on the biological population diversity assessment method. Firstly, the heterogeneity quantification method, i.e., method 1, is based on system complexity and difference. On this basis, another heterogeneous quantification method, i.e., method 2, is established using high order symbiosis of the vulnerabilities. The experimental results show that, compared to the known methods, the heterogeneous quantification method 1 considers more comprehensive factors and is closer to reality. The heterogeneity quantification method 2 is more instructive to quantify the security of the mimic control plane.

Weakly nonlinear two dimensional wave scattering in incompressible pre-stressed materials: Far field approximation

We develop a series expansion approach to the calculation of the scattering coefficients of in-plane transverse elastic waves. The waves are scattered by a cylindrical obstacle as they propagate through an incompressible nonlinear material which is inhomogeneously pre-stressed. We deal with the calculation using a distorted wave Born approximation in the far field. A neo-Hookean strain energy function is considered for the incompressible elastic material, and a rigid cylinder is considered as an obstacle. From the static equilibrium configuration, a small-on-large approach is constructed via a series expansion of the wave equation which allows us to compute both the scattered wave and the induced pressure field, and their dependence on the applied pre-stressed. In the far field limit, the pre-stress effect on the scattering coefficients is calculated via partial waves. The formalism can be expanded directly to three-dimensional media with different obstacle symmetries.

Exploring the Impact of Geometry and Fibre Arrangements on Daylight Control in Bistable Kinetic Shades

Bistable laminates are composite structures that exhibit more than one static configuration, showing a "snap-through" behaviour that results from residual stresses generated during the curing process. This study focuses on finding adequate fibre and laminate arrangements for bistable laminates used in functional kinetic shadings. We present a study with a mixed-methods approach, combining experimental prototyping and performance simulation studies. We fabricated and analysed the geometry of a series of prototypes, conducting daylight studies to assess the performance of different laminates and fibre arrangements and showing how specific fibre arrangements can help control daylight throughout the day. We concluded that controlling fibre arrangements of bistable laminates could increase the functionality of bistable kinetic shadings in terms of daylight control, leading to more differentiated shapes between their two stable states, which corresponds to the open and closed positions of the shadings. Increasing such a difference increases the range of system configurations and, therefore, the ability to respond to various external lighting conditions and internal user requirements.

G-ADRR: Network-Wide Slicing of Wi-Fi Networks With Variable Loads in Space and Time

As part of 3GPP releases 15 and 16 Wi-Fi networks have been integrated with the 5G Core, which is a key feature in private network scenarios. Another important feature for private networks is multi-tenancy, whereby an infrastructure provider shares a common radio access network among several tenants subject to service level agreements (SLAs). 3GPP has defined network slicing on the radio access segment supporting multi-tenancy for 5GNR, but a similar feature is lacking in Wi-Fi networks. In this paper we present G-ADRR, which, to be best of our knowledge, is the first global slicing policy for Wi-Fi that delivers per-tenant radio level SLAs over a given geographical area. We extensively evaluate the performance of G-ADRR by means of an experimental prototype and packet level simulations, and demonstrate its advantages as compared to two alternative global scheduling strategies and a static slice configuration policy commonly used in the state-of-the-art.