Minimum Field Research Articles

An Innovative approach towards image encryption by using novel PRNs and S-boxes Modeling techniques

Efficient multiple pseudo-random number sequences (PRNS) and substitution boxes (S-boxes) are one of the most significant building blocks, which are jointly adopted normally for secure data encryption. Multiple aspects pave the way to handle large-scale multimedia data. However, the computational efforts on multiple constructions may certainly lead to limits the required ciphering through-put. Therefore, reducing the computational cost of multiple patterns such as PRNS and S-boxes is the core requirement for an efficient cryptosystem. For this achievement, we exploited the indexing technique over elliptic curves with small prime fields to introduce a computationally efficient mechanism for both multiple PRNS and multiple S-boxes. In the newly constructed PRNS and S-boxes, we used collectively EC group law and simple algebraic operations to get the security strength as well as low computational cost respectively. Based on statistical results, the proposed S-box mechanism is the most effective method that generates efficient multiple S-boxes on minimum prime fields. Likewise, the PRNS’s simulation results shows that the proposed mechanism is the highly effective model for generating multiple verified pseudo random patterns on small prime fields in a single round. These assessments indicates that the proposed mechanism offers desired key-space, better statistical features of encrypted data and less computational cost.

Evolutionary implications of a magnetar interpretation for GLEAM-X J162759.5–523504.3

ABSTRACT The radio pulsar GLEAM-X J162759.5–523504.3 has an extremely long spin period ($P = 1091.17\, \mbox{s}$), and yet seemingly continues to spin-down rapidly ($\dot{P} < 1.2 \times 10^{-9}\, \mbox{ss}^{-1}$). The magnetic field strength that is implied, if the source is a neutron star undergoing magnetic dipole braking, could exceed $10^{16}\, \mbox{G}$. This object may therefore be the most magnetized neutron star observed to date. In this paper, a critical analysis of a magnetar interpretation for the source is provided. (i) A minimum polar magnetic field strength of $B \sim 5 \times 10^{15}\, \mbox{G}$ appears to be necessary for the star to activate as a radio pulsar, based on conventional ‘death valley’ assumptions. (ii) Back-extrapolation from magnetic braking and Hall–plastic–Ohm decay suggests that a large angularize momentum reservoir was available at birth to support intense field amplification. (iii) The observational absence of X-rays constrains the star’s field strength and age, as the competition between heating from field decay and Urca cooling implies a surface luminosity as a function of time. If the object is an isolated, young ($\sim 10\, \mbox{kyr}$) magnetar with a present-day field strength of $B \gtrsim 10^{16}\, \mbox{G}$, the upper limit ($\approx 10^{30}\, \mbox{erg s}^{-1}$) set on its thermal luminosity suggests it is cooling via a direct Urca mechanism.

Protein Dielectrophoresis with Gradient Array of Conductive Electrodes Sheds New Light on Empirical Theory.

Dielectrophoresis (DEP) is a versatile tool for the precise microscale manipulation of a broad range of substances. To unleash the full potential of DEP for the manipulation of complex molecular-sized particulates such as proteins requires the development of appropriate theoretical models and their comprehensive experimental verification. Here, we construct an original DEP platform and test the Hölzel-Pethig empirical model for protein DEP. Three different proteins are studied: lysozyme, BSA, and lactoferrin. Their molecular Clausius-Mossotti function is obtained by detecting their trapping event via the measurement of the fluorescence intensity to identify the minimum electric field gradient required to overcome dispersive forces. We observe a significant discrepancy with published theoretical data and, after a very careful analysis to rule out experimental errors, conclude that more sophisticated theoretical models are required for the response of molecular entities in DEP fields. The developed experimental platform, which includes arrays of sawtooth metal electrode pairs with varying gaps and produces variations of the electric field gradient, provides a versatile tool that can broaden the utilization of DEP for molecular entities.

Increasing the Accuracy Characteristics of Focused Electromagnetic Devices for Non-Destructive Testing and Technical Diagnostics by Implementing Sum–Difference Signal Processing

Nowadays, the classical aperture theory is supplemented by data on the properties of electromagnetic fields in the near radiated field zone. A fundamental feature of the functioning of antennas in this area is the possibility of spatial focusing of electromagnetic energy. In this case, it is possible to realize the maximum field strength at a given point in space and reduce the field strength outside this point. The focusing effect itself is provided by the in-phase addition of fields from elementary sources. Also, in addition to the formation of the maximum field strength at the focusing point, it is also possible to realize a minimum field strength at the focusing point by implementing antiphase addition of partial fields at the focusing point. The fundamental possibility of forming sum and difference amplitude distributions of electromagnetic fields in the near radiated field zone makes it possible to realize sum–difference signal processing in order to reduce the level of the secondary maximum of the focused field. This article discusses the features of the formation of the sum and difference amplitude distributions and the principles of the sum–difference processing of focused electromagnetic fields, along with the implementation of technical solutions for non-destructive testing and technical diagnostic tasks.

Ultra-fast Surrogate Model for Magnetic Field Computation of a Superconducting Magnet Using Multi-layer Artificial Neural Networks

Due to the inherent nonlinear and sophisticated nature of superconducting wires/tapes, magnetic field computation of superconducting magnets by means of finite element methods (FEMs) is a time-consuming and complicated procedure. Although Legendre series method (LSM) was proposed as an alternative of FEMs, LSMs are not still fast enough. In current research, a surrogate model based on multi-layer artificial neural networks (ANNs) was introduced for the first time to dramatically reduce the computation time of a magnetic resonance imaging (MRI) magnet. To do this, firstly, the data related to the magnetic field were extracted based on LSM simulations for around 5000 different coil geometries. After that, the geometries of coils were used as inputs to a semi-deep learning ANN-based model in MATLAB software package. The minimum magnetic field in diameter spherical volume, maximum and minimum of total magnetic field were considered as outputs of the model, known as field indices. Then, ANN model was trained to calculate these field indices for any coil geometry. By doing so, magnetic field indices were estimated with a high accuracy based on the target values and also with extremely higher speed, comparing to FEM and LSM. Results showed that it takes 15 to 17 s for the proposed model to calculate the field indices for 750 different geometries whereas it takes for LSM-based model about 4 h.

Improving the spectral resolution and measurement range of quantum microwave electrometry by cold Rydberg atoms

We theoretically and experimentally studied quantum microwave electrometry in a cold atomic system using Rydberg electromagnetic induction transparency (EIT) and Autler–Townes splitting (EIT-AT splitting). In cold atoms, a spectral linewidth of ∼500 kHz for EIT was achieved owing to a significant reduction in residual Doppler width, i.e. by at least an order of magnitude, compared to that in vapor cells at room temperature. Therefore, the minimum microwave electric field intensity (E MW) that can be measured is 430 µV cm−1, which is one order higher sensitivity in the EIT-AT regime than that in vapor cells at room temperature. Unlike microwave electrometry in atomic vapor cells, EIT-AT splitting cannot be observed if E MW is so large that the EIT-AT splitting interval exceeds the absorption peak width of the cold atom while scanning the frequency of the probe laser (ω p ). Moreover, EIT-AT splitting can be observed if exceeds the natural linewidth of the intermediate states while scanning the coupling laser (ω c ) and maintains a high spectral resolution with a high signal-to-noise ratio. While scanning ω c , the upper microwave electric field intensity is limited by the scanning range of our setup. Using our system, we measure the maximum field to be 21.6 mV cm−1, nearly three times higher than that of 6.8 mV cm−1 while scanning ω p . The results indicate that the linear range of E MW measured using EIT-AT splitting considerably improves in cold Rydberg atoms.

Optimal Design of Corona Ring for 132 kV Insulator at High Voltage Transmission Lines Based on Optimisation Techniques

The installation of a corona ring on an insulator string on a transmission line is one of the solutions to reduce the electric field stress surrounding the energised end of the insulator string. However, installing a corona ring with an optimum design to reduce the electric field magnitude on an insulator string is a challenging task. Therefore, in this work, a method to achieve the optimum design of a corona ring for 132 kV composite non-ceramic insulator string was proposed using two optimisation methods: the Imperialist Competitive Algorithm (ICA) and Grey Wolf Optimisation (GWO). A composite non-ceramic insulator string geometry with and without a corona ring was modelled in finite element analysis and used to obtain the electric field distribution in the model geometry. The electric field distribution was evaluated using a variation in the corona ring’s dimensions, i.e., the ring diameter, the ring tube diameter and the vertical position of the ring along the insulator string. From the results achieved, a comparison of the minimum electric field magnitude along the insulator string with a corona ring design shows that the minimum electric field magnitude is found to be lower using optimisation techniques compared to without using optimisation techniques by between 3.724% and 3.827%. Hence, this indicates the capability and effectiveness of the proposed methods in achieving the optimum design of a corona ring on an insulator string.

Optimal design of dual air-gap closed-loop TMR current sensor based on minimum magnetic field uniformity coefficient

Advanced sensor technology provides accurate information for transparent monitoring and real-time control of the power grid. Tunnel magnetoresistance (TMR) elements with high sensitivity and linearity provide a new technical means for current measurement in medium-voltage DC power distribution systems. This paper proposes a dual air-gap closed-loop TMR current sensor and its optimal design method based on the magnetic field’s minimum uniformity coefficient. The dual air-gap structure reduces the measurement error caused by the eccentricity of the wire, and the theory and modelling of the minimum magnetic field uniformity coefficient optimise the key parameters, such as the inner radius of the magnetic core, the distance of the air-gap and the area size of the section side. Finally, a sensor prototype with a rated measurement current of ± 50 A was developed. The experiment results show that the relative error of the proposed TMR current sensor is less than 0.2% under the rated current. The conclusion can be drawn that the proposed sensor with the optimised design effectively improves the measurement accuracy.

An improved authentication scheme for BLE devices with no I/O capabilities

Bluetooth Low Energy (BLE) devices have become very popular because of their Low energy consumption and prolonged battery life. They are being used in smart wearable devices, home automation systems, beacons, and many more areas. BLE uses pairing mechanisms to achieve a level of peer entity authentication as well as encryption. Although there are a set of pairing mechanisms available, BLE devices with no keyboard or display mechanism (and hence using the Just Works pairing) are still vulnerable. In this paper, we propose and implement a light-weight digital certificate-based authentication mechanism for the BLE devices using the Just Works model. The proposed model is an add-on to the existing pairing mechanism and can be easily incorporated into the existing BLE stack. To counter the Man-in-The-Middle attack scenario in Just Works pairing (device spoofing), our proposed model allows the client and peripheral to use the popular Public Key Infrastructure (PKI) to establish peer entity authentication and a secure cryptographic tunnel for communication. We have also developed a light-weight BLE profiled digital certificate containing the bare minimum fields required for resource-constrained devices, which significantly reduces the memory (about 90% reduction) and energy consumption. We have experimentally evaluated the device’s energy consumption and execution time using the proposed pairing mechanism to demonstrate that the model can be easily deployed with fewer changes to the power requirements of the chips. The model has been formally verified using an automatic verification tool for protocol testing.

Deriving Large Coronal Magnetic Loop Parameters Using LOFAR J Burst Observations

Large coronal loops around one solar radius in altitude are an important connection between the solar wind and the low solar corona. However, their plasma properties are ill-defined, as standard X-ray and UV techniques are not suited to these low-density environments. Diagnostics from type J solar radio bursts at frequencies above 10 MHz are ideally suited to understand these coronal loops. Despite this, J-bursts are less frequently studied than their type III cousins, in part because the curvature of the coronal loop makes them unsuited for using standard coronal density models. We used LOw-Frequency-ARray (LOFAR) and Parker Solar Probe (PSP) solar radio dynamic spectrum to identify 27 type III bursts and 27 J-bursts during a solar radio noise storm observed on 10 April 2019. We found that their exciter velocities were similar, implying a common acceleration region that injects electrons along open and closed magnetic structures. We describe a novel technique to estimate the density model in coronal loops from J-burst dynamic spectra, finding typical loop apex altitudes around 1.3 solar radius. At this altitude, the average scale heights were 0.36 solar radius, the average temperature was around 1 MK, the average pressure was 0.7~text{mdyn},text{cm}^{-2}, and the average minimum magnetic field strength was 0.13 G. We discuss how these parameters compare with much smaller coronal loops.

Study on Burning Surface Regression Algorithm under Erosive Burning Based on CT Images of Solid Rocket Motor Grain

The presence of the erosive burning effect during the operation of a solid rocket motor (SRM) is one of the most important factors affecting the proper operation of the motor. To solve the effects of the operating process of the motor under erosive burning, a synthesis algorithm based on the actual CT images is proposed to combine the Level-set (LS) method with the minimum distance function (MDF) method for the simulation of the burning surface regression of the grain under erosive burning. The Hamilton–Jacobi control equation can be solved exactly for the discrete form of LS. To improve the computational efficiency of the LS method, the minimum distance field is initialized and only the distortion grid is adjusted during the reinitialization. The third-order TVD Runge–Kutta method is used to solve the problem of numerical oscillation and improve the calculation accuracy. The experiments simulate the burning process of the NAWC No. 6 partial grain under erosive burning, which can provide the main basis for the performance design of solid propellant. The experimental results show that the method has good applicability to three-dimensional complex grains. It can realize the simulation of grains under erosive burning and its calculation accuracy is high.

WATER CENTRIFUGAL PUMP, DESIGN AND FLUID FLOW ANALYSIS

In this article we have designed the active parts of a centrifugal pump (volute casing and impeller) often used in the naval field, especially for ballasting installations of commercial shipping vessels. Data on dimensions, geometry and mode of operation were used from specialized technical documentation and the works of other authors. The design of the volute casing and impeller assembly was done with NX SIEMENS. The study of the fluid flow was done with ANSYS CFX by importing the whole, some conclusions were drawn regarding the fluid velocities and the pressure field. The influence of the cavitation phenomenon was taken into account by modelling this phenomenon, thus avoiding the appearance of the minimum negative pressures field. It is known what is the adverse influence of the cavitation phenomenon and what are the factors that can reduce the occurrence of this phenomenon.

Concept of scanning magnet with distributed winding coils for particle beam therapy

To reduce the size of a rotating gantry for a particle therapy system, it is desirable to reduce the size of the scanning system by substituting separated scanning magnets with a combined-function scanning magnet. A two-dimensionally designed scanning magnet with distributed winding coils (DW-SCM) is proposed. The DW-SCM can generate a rotating dipole magnetic field using a single power supply. The two-dimensional static magnetic field distributions of the DW-SCM were calculated using poisson superfish code and compared with those of an octupole scanning magnet (CW-SCM) and cos-theta-type scanning magnet ($\mathrm{Cos}\ensuremath{\theta}$-SCM) with the same bore diameter of 98 mm. The calculated two-dimensional magnetic field showed that the DW-SCM had the highest magnetic field strength of the three types of scanning magnets, and compared with the CW-SCM, the DW-SCM was 129% higher and the $\mathrm{cos}\text{ }\ensuremath{\theta}$-SCM was 72% higher. The good field region (radius) of field homogeneity within $\ifmmode\pm\else\textpm\fi{}0.5%$ of the DW-SCM had a symmetrical shape centered on a current phase of 30\ifmmode^\circ\else\textdegree\fi{}, and the minimum value was 24 mm. Also compared with the CW-SCM, the minimum good field region was 11% higher for the DW-SCM and 65% higher for the $\mathrm{cos}\text{ }\ensuremath{\theta}$-SCM. The results indicate that the proposed scanning magnet could generate a high-strength rotating dipole magnetic field, and it might be possible to reduce the size of a scanning system by substituting separated scanning magnets with the DW-SCM.

Design Analysis of Heat Sink Using the Field Synergy Principle and Multitarget Response Surface Methodology

This study describes a novel heat sink design approach employs the field synergy concept and multitarget response surface methodology (RSM). The multiobjective response surface methodology can be used to determine the simulation equations that will maximize the heat transfer of fins at various fin heights, fin angles, and fin circumferences, when considering the impact of jet flow heat exchange. The goal of the response value was to maintain the minimum possible average field coangle and fin temperature. The results show that the ideal heat sink size would be the following: fins with a height of 50 mm, an angle of 60 degrees, and the number of fins equal to five. We examined the impact of wall speed on the heat transfer caused by the field synergy angle. Our findings suggest that with the synchromesh of the display field, heat-dissipation efficiency rises.

Enhanced Piezoelectric Properties in a Single-Phase Region of Sm-Modified Lead-Free (Ba,Ca)(Zr,Ti)O3 Ceramics.

In ferroelectric materials, phase boundaries such as the morphotropic phase boundary (MPB) and polymorphic phase boundary (PPB) have been widely utilized to enhance the piezoelectric properties. However, for a single-ferroelectric-phase system, there are few effective paradigms to achieve the enhancement of piezoelectric properties. Herein, we report an unexpected finding that largely enhanced piezoelectric properties occur in a single-tetragonal-ferroelectric-phase region in the Sm-modified (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT-xSm) system. An electrostrain maximum (0.13%) appears in the single-phase region of the BZCT-0.5Sm composition with the maximum polarization (Pm = 18.37 µC/cm2) and piezoelectric coefficient (d33 = 396 pC/N) and the minimum coercive field (EC = 3.30 kV/cm) at room temperature. Such an enhanced piezoelectric effect is due to the synergistic effect of large lattice distortion and domain miniaturization on the basis of the transmission electron microscope (TEM) observation and X-ray diffraction (XRD) Rietveld refinement. Our work may provide new insights into the design of high-performance ferroelectrics in the single-phase region.

A Multiscale Picture of the Magnetic Field and Gravity from a Large-scale Filamentary Envelope to Core-accreting Dust Lanes in the High-mass Star-forming Region W51

We present 230 GHz continuum polarization observations with the Atacama Large Millimeter/Submillimeter Array at a resolution of 0.″1 (∼540 au) in the high-mass star-forming regions W51 e2 and e8. These observations resolve a network of core-connecting dust lanes, marking a departure from earlier coarser, more spherical continuum structures. At the same time, the cores do not appear to fragment further. Polarized dust emission is clearly detected. The inferred magnetic field orientations are prevailingly parallel to dust lanes. This key structural feature is analyzed together with the local gravitational vector field. The direction of local gravity is found to typically align with dust lanes. With these findings, we derive a stability criterion that defines a maximum magnetic field strength that can be overcome by an observed magnetic field–gravity configuration. Equivalently, this defines a minimum field strength that can stabilize dust lanes against a radial collapse. We find that the detected dust lanes in W51 e2 and e8 are stable, hence possibly making them a fundamental component in the accretion onto central sources, providing support for massive star formation models without the need of large accretion disks. When comparing to coarser resolutions, covering the scales of envelope, global, and local collapse, we find recurring similarities in the magnetic field structures and their corresponding gravitational vector fields. These self-similar structures point at a multiscale collapse-within-collapse scenario until finally the scale of core-accreting dust lanes is reached where gravity is entraining the magnetic field and aligning it with the dust lanes.

A large bandwidth optical fiber magnetic field sensor based on Sagnac interferometer

In this paper, a fiber magnetic field sensor is proposed based on Terfenol-D and Sagnac interferometer. The mechanism of the sensor is deduced theoretically. As the frequency of the magnetic field increases, on the one hand, the sensitivity is enhanced because the response to the high-frequency non-reciprocal phase differences is intensified in the Sagnac interferometer. On the other hand, the sensitivity is suppressed by the eddy current effect. Then it exhibits significant linear response to alternating magnetic field in a certain frequency range. The sensor performances, such as frequency response, linear range, and noise, are analyzed theoretically and demonstrated experimentally. Experimental results show that the sensor has a 3 dB bandwidth from 100 Hz to 2500 Hz, and the excellent linearity and reversibility from 0 to 274.05 μT (rms). The high sensitivity of 1.34 mV/μT (rms) and minimum detectable magnetic field of 25 nT/√Hz (rms) are achieved at 500 Hz. The sensor with large bandwidth and wide measuring range is suitable for detecting weak alternating magnetic field.

On Calculating the Phase-to-Phase CFO of Overhead Transmission Lines Based on the Spatial Minimum Electric Field

A spatial approach for calculating phase-to-phase switching impulse critical flashover voltage of overhead transmission lines is implemented using the Fourier enhanced charge simulation method (FEnCSM). Cathode-directed leader and streamer characteristics are used in an engineering model of pre-breakdown conditions. Rather than identifying breakdown based on complete bridging of the air gap, the proposed method identifies breakdown based on the ability of the leader-streamer system to survive the region of minimum electric field between phase conductors. Use of the minimum field as a basis for identifying breakdown allows anode-directed negative streamers to be reasonably neglected. Combined with FEnCSM, the proposed approach enables explicit representation of phase bundle subconductors and avoids the electrode-specific geometric constants or gap factors common in existing methods. Results obtained with the method compare well to four independent sets of experimental data for phase-to-phase flashover from the literature. The method was developed to facilitate ongoing research into practical use of the electric field as a basis for unifying electrical studies in the design of overhead transmission lines, including HSIL and other novel configurations.

X-ray flares of the young planet host Ds Tucanae A

The discovery of planets around young stars has spurred novel studies of the early phases of planetary formation and evolution. Stars are strong emitters at X-ray and UV wavelengths in their first billion of years and this strongly affects the evaporation, thermodynamics, and chemistry in the atmospheres of the young planets orbiting around them. In order to investigate these effects in young exoplanets, we observed the 40 Myr old star DS Tuc A with XMM-Newton. We recorded two X-ray bright flares, with the second event occurring about 12 ks after the first one. Their duration, from the rise to the end of the decay, was about 8 − 10 ks in soft X-rays (0.3–10 keV). The flares were also recorded in the 200–300 nm band with the UVM2 filter of the Optical Monitor. The duration of the flares in UV was about 3 ks. The observed delay between the peak in the UV band and in X-rays is a probe of the heating phase, followed by evaporation and an increase in the density and emission of the flaring loop. The coronal plasma temperature at the two flare peaks reached 54–55 MK. Diagnostics based on the temperatures and timescales of the flares applied to these two events have allowed us to infer a loop length of 5 − 7 × 1010 cm, which is about the extent of the stellar radius. We also inferred the values of electron density at the flare peaks of 2.3 − 6.5 × 1011 cm−3, along with a minimum magnetic field strength on the order of 300–500 G that is needed to confine the plasma. The energy released during the flares was on the order of 5 − 8 × 1034 erg in the bands 0.3 − 10 keV and 0.9 − 2.7 × 1033 erg in the UV band (200–300 nm). We speculate that the flares were associated with coronal mass ejections (CMEs) that hit the planet about 3.3 h after the flares, which dramatically increased the rate of evaporation for the planet. From the RGS spectra, we retrieved the emission measure distribution and the abundances of coronal metals during the quiescent and flaring states, respectively. Finally, we inferred a high electron density measurement, which is in agreement with the inferences drawn from time-resolved spectroscopy and EPIC spectra, as well as the analysis of RGS spectra during the flares.

Magnetic field spectrum analyzer using nonlinear magnetoelectric effect in composite ferromagnet - piezoelectric heterostructure

Industrial machines and mechanisms, household appliances, natural sources and biological objects generate weak magnetic fields with amplitudes of ~10 –12 – 10 –4 T in the frequency band of ~1–10 5 Hz. Analysis of the fields’ characteristics allows to get information about internal processes and performance of these sources in a non-contact way, to carry out medical diagnostics. This makes topical the development of low-frequency magnetic field spectrum analyzers. The paper describes a spectrum analyzer of a new type using nonlinear effect of magnetic field mixing in a composite ferromagnet-piezoelectric heterostructure. The main element of the analyzer is a magnetic field mixer which contains a piezoelectric langatate single-crystal sandwiched between two layers of a magnetostrictive amorphous alloy. With simultaneous action of the measured magnetic field and the excitation magnetic field on the structure and fulfillment of the frequency matching conditions, the structure generates a voltage at the electromechanical resonance frequency. Swept-tuned spectrum analysis of the measured field is carried out by tuning the frequency of the excitation field. A prototype of the analyzer is fabricated and characterized. It operates in the frequency band of 0.1–85 kHz, has a frequency resolution of ~40 Hz, a minimum detectable field of 50 nT, and a dynamic range of 35 dB. Possibilities to improve characteristics of magnetic field spectrum analyzers are discussed. • A new swept-tuned spectrum analyzer of magnetic fields is proposed. • The analyzer uses resonant magnetoelectric effect of magnetic field frequency mixing. • A prototype of the spectrum analyzer is fabricated and characterized.