External Electromagnetic Sources Research Articles

Quantum Advantage in a Molecular Spintronic Engine that Harvests Thermal Fluctuation Energy.

Recent theory and experiments have showcased how to harness quantum mechanics to assemble heat/information engines with efficiencies that surpass the classical Carnot limit. So far, this has required atomic engines that are driven by cumbersome external electromagnetic sources. Here, using molecular spintronics, an implementation that is both electronic and autonomous is proposed. The spintronic quantum engine heuristically deploys several known quantum assets by having a chain of spin qubits formed by the paramagnetic Co center of phthalocyanine (Pc) molecules electronically interact with electron-spin-selecting Fe/C60 interfaces. Density functional calculations reveal that transport fluctuations across the interface can stabilize spin coherence on the Co paramagnetic centers, which host spin flip processes. Across vertical molecular nanodevices, enduring dc current generation, output power above room temperature, two quantum thermodynamical signatures of the engine's processes, and a record 89% spin polarization of current across the Fe/C60 interface are measured. It is crucially this electron spin selection that forces, through demonic feedback and control, charge current to flow against the built-in potential barrier. Further research into spintronic quantum engines, insight into the quantum information processes within spintronic technologies, and retooling the spintronic-based information technology chain, can help accelerate the transition to clean energy.

Application of photogrammetry reconstruction for hyperthermia quality control measurements

PurposeHyperthermia is a cancer treatment in which the target region is heated to temperatures of 40–44 °C usually applying external electromagnetic field sources. The behavior of the hyperthermia applicators (antennas) in clinical practice should be periodically checked with phantom experiments to verify the applicator’s performance over time. The purpose of this study was to investigate the application of photogrammetry reconstructions of 3D applicator position in these quality control procedure measurements. MethodsPhotogrammetry reconstruction was applied at superficial hyperthermia scenario using the Lucite cone applicator (LCA) and phased-array heating in the head and neck region using the HYPERcollar3D. Wire-frame models of the entire measurement setups were created from multiple-view images and used for recreation of the setup inside 3D electromagnetic field simulation software. We evaluated applicator relation (Ra) between measured and simulated absolute specific absorption rate (SAR) for manually created and photogrammetry reconstructed simulation setups. ResultsWe found a displacement of 7.9 mm for the LCA and 8.2 mm for the HYPERcollar3D setups when comparing manually created and photogrammetry reconstructed applicator models placements. Ra improved from 1.24 to 1.18 for the LCA and from 1.17 to 1.07 for the HYPERcollar3D when using photogrammetry reconstructed simulation setups. ConclusionPhotogrammetry reconstruction technique holds promise to improve measurement setup reconstruction and agreement between measured and simulated absolute SAR.

Probing upper mantle electrical conductivity with daily magnetic variations using global-to-local transfer functions

Summary We present new transfer functions (TFs) that can handle external electromagnetic (EM) sources of complex geometry. These TFs relate global expansion coefficients describing the source with a locally measured EM field. In this study, the new TFs concept was applied to the daily magnetic variations measured at the ground. The parameterisation of the source in terms of spherical harmonics was adopted. We used nearly 20 years of data from 125 mid-latitude observatories and explored how the results are affected by (I) solar activity conditions, (II) the choice of the prior conductivity model used for the source coefficient estimation, and (III) the presence of ocean tidal magnetic signals. We found that choosing magnetically quiet periods is beneficial due to simpler source morphology, and the choice of prior conductivity model may significantly affect the source coefficients and TFs at short periods. We further observed significant contributions by ocean tidal magnetic signals at coastal and island observatories and corrected for them. Finally, the estimated TFs were inverted for the mantle conductivity at several locations representing different geological settings.

Self-powered smart active RFID tag integrated with wearable hybrid nanogenerator

Radio frequency identification (RFID) technology is essential to construct the Internet of Things (IoT), which is significant to promote the blooming development of the new-generation information technology. RFID tags are widely used in many identification fields due to the non-contact, low-power-consumption and rapid feature for target recognition. However, the working distance of traditional passive RFID tags is extremely short at millimeter level in a limited direction range, since the power supply is passively delivered by an external electromagnetic radiation source. Moreover, the information transmission of traditional passive RFID tags is simplex in only one direction from RFID tag to the monitor, and in other words, the pre-stored information in passive RFID tags can only be passively detected by the monitor. Herein, a self-powered smart active RFID tag integrated with wearable hybrid nanogenerator is developed to overcome these drawbacks above. A new power supply strategy for RFID tags were proposed by the integration of a wearable nanogenerator based on the triboelectric-electromagnetic hybrid mechanisms, which can effectively convert the biomechanical energy into electricity to sustainably power RFID tags. The fabricated triboelectric-electromagnetic hybrid nanogenerator (TEHN) showed a remarkable performance with the maximum power density of 6.79 W/m2. A new transistors-controlled power management module (PMM) circuit of automatic parallel-series transformation of capacitors was proposed and also integrated to enhance the charging capability of TEHN by shortening 50% charging time. The integration of TEHN and PMM enable this active RFID tag to work autonomously with a 330-fold enhancement of working distance up to 33 m, and its working direction range is overcome to be omnidirectional. Furthermore, the developed active RFID tag can work in duplex communication mode to exchange the information with the monitor. This all-in-one self-powered smart active RFID tag was successfully demonstrated to remotely control the automatic door and be a wearable microsystem for ultra-large-area target recognition, which show an attractive potential in many application fields.

Shielding Effectiveness of Open Cabinet Containing Digital Modules Using Ferrite Sheet

This paper presents an enhancement in the shielding effectiveness (SE) of an open cabinet containing digital modules using a ferrite sheet when an external electromagnetic source impinges on the gate of the cabinet. We perform an electromagnetic analysis on the inner space of an open cabinet using a mode-matching method, which proceeds in the following order: the separation of the analyzed region, the representation of fields, and the enforcement of the boundary conditions on the tangential field continuities between the separated regions. To be specific, it is efficiently utilized in the representation of electric and magnetic fields by Helmholtz’s equation in conjunction with both the separation of the variable and the Fourier transform. After confirming the convergence of the solutions to the set of simultaneous equations, we investigate the SE in the open cabinet in terms of a frequency, an incident angle, and the number and the size of slits. The computed results provide us with useful information for avoiding electromagnetic interference. We then examine the improvement of shielding performance by inserting a ferrite sheet at the gate of a cabinet. We verify that the usage of the ferrite sheet with high permeability can be a preferable solution for removing the undesirable problems caused by an external electromagnetic source.

Erratum to: Electromagnetic shielding effectiveness and mechanical properties of graphite-based polymeric films

Modern electronics have nowadays evolved to offer highly sophisticated devices. It is not rare; however, their operation can be affected or even hindered by the surrounding electromagnetic radiation. In order to provide protection from undesired external electromagnetic sources and to ensure their unaffected performance, electromagnetic shielding is thus necessary. In this work, both the electromagnetic and mechanical properties of graphite-based polymeric films are studied. The investigated films show efficient electromagnetic shielding performance along with good mechanical stiffness for a certain graphite concentration. To the best of our knowledge, the present study illustrates for the first time both the electromagnetic shielding and mechanical properties of the polymer composite samples containing graphite filler at such high concentrations (namely 60–70 %). Our findings indicate that these materials can serve as potential candidates for several electronics applications.

Analytical solution of the induced currents in multilayer cylindrical conductors under external electromagnetic sources

We present a closed-form solution for the induced losses in round conductors consisting of several concentric layers. The geometry under study corresponds to an infinitely-long and isolated multilayer cylinder where layers can have different electromagnetic properties and the number of layers is not restricted. The multilayer conductor is under an external time-varying magnetic field which induces currents and, accordingly, generates Joule dissipation. Total induced losses are obtained by integrating the losses of each layer. Mathematical expressions of the current distribution in each layer are derived from the solution of Maxwell’s equations. These expressions consist of a combination of Bessel functions of different kinds and orders. The current distribution in a particular layer not only depends on the properties of the layer but also on the properties of the rest of layers. Consequently, matrix formalism is adopted for describing current distribution of layers. Matrix description is numerically solved and results are compared with finite element simulations for different arrangements and cases.

Investigation of assumptions underlying current safety guidelines on EM-induced nerve stimulation

An intricate network of a variety of nerves is embedded within the complex anatomy of the human body. Although nerves are shielded from unwanted excitation, they can still be stimulated by external electromagnetic sources that induce strongly non-uniform field distributions. Current exposure safety standards designed to limit unwanted nerve stimulation are based on a series of explicit and implicit assumptions and simplifications. This paper demonstrates the applicability of functionalized anatomical phantoms with integrated coupled electromagnetic and neuronal dynamics solvers for investigating the impact of magnetic resonance exposure on nerve excitation within the full complexity of the human anatomy. The impact of neuronal dynamics models, temperature and local hot-spots, nerve trajectory and potential smoothing, anatomical inhomogeneity, and pulse duration on nerve stimulation was evaluated. As a result, multiple assumptions underlying current safety standards are questioned. It is demonstrated that coupled EM-neuronal dynamics modeling involving realistic anatomies is valuable to establish conservative safety criteria.

Helical currents in metallic Rashba strips

We study the texture of helical currents in metallic planar strips in the presence of Rashba spin-orbit coupling (RSOC) on the lattice at zero temperature. In the noninteracting case, and in the absence of external electromagnetic sources, we determine by exact numerical diagonalization of the single-particle Hamiltonian, the distribution across the strip section of these Rashba helical currents (RHC) as well as their sign oscillation, as a function of the RSOC strength, strip width, electron filling, and strip boundary conditions. Then, we study the effects of charge currents introduced into the system by an Aharonov-Bohm flux for the case of rings or by a voltage bias in the case of open strips. The former setup is studied by variational Monte Carlo, and the later, by the time-dependent density-matrix-renormalization group technique. Particularly for strips formed by two, three and four coupled chains, we show how these RHC vary in the presence of such induced charge current, and how their differences between spin-up and spin-down electron currents on each chain, help to explain the distribution across the strip of charge currents, both of the spin conserving and the spin flipping types. We also predict the appearance of polarized charge currents on each chain. Finally, we show that these Rashba helical currents and their derived features remain in the presence of an on-site Hubbard repulsion as long as the system remains metallic, at quarter filling, and even at half-filling where a Mott-Hubbard metal-insulator transition occurs for large Hubbard repulsion.

Matrix Code Based Error Correction for LUT Based Cyclic Redundancy Check

Communication is one of the vast and rapidly growing fields of engineering. Increasing the efficiency of communication by overcoming the external electromagnetic sources and noise is a challenging task. Various error detection and correction methods are introduced to reduce the loss of data while transmission. This paper proposes a novel method which use Cyclic Redundancy Check(CRC) for the error detection and the generated CRC error is corrected by using Hybrid Matrix Code(HMC) and they are coded in verilog HDL and simulated using Xilinx ISE Design suite 14.2. This proposed method can provide maximum error detection and correction capability with reduction in delay.

Processes of conversion of a hot metal particle into aerogel through clusters

Processes are considered for conversion into a fractal structure of a hot metal micron-size particle that is located in a buffer gas or a gas flow and is heated by an external electric or electromagnetic source or by a plasma. The parameter of this heating is the particle temperature, which is the same in the entire particle volume because of its small size and high conductivity. Three processes determine the particle heat balance: particle radiation, evaporation of metal atoms from the particle surface, and heat transport to the surrounding gas due to its thermal conductivity. The particle heat balance is analyzed based on these processes, which are analogous to those for bulk metals with the small particle size, and its high temperature taken into account. Outside the particle, where the gas temperature is lower than on its surface, the formed metal vapor in a buffer gas flow is converted into clusters. Clusters grow as a result of coagulation until they become liquid, and then clusters form fractal aggregates if they are removed form the gas flow. Subsequently, associations of fractal aggregates join into a fractal structure. The rate of this process increases in medium electric fields, and the formed fractal structure has features of aerogels and fractal fibers. As a result of a chain of the above processes, a porous metal film may be manufactured for use as a filter or catalyst for gas flows.

Quantum-matter photonic framework perspective of chemical processes: Entanglement shifts in HCN/CNH isomerization

A complete electro-nuclear (EN) basis set and quantum electrodynamics bases in photon number scheme combines to form photonic bases sets. The EN q-states can hence be modulated by appropriate external electromagnetic sources. Quantum determinants for HCN/CNH isomerization within photonic bases are elaborated that rationalize quantum state changes as if it were an apparent unimolecular process. Topologic label of base states permit linking with those obtained with semiclassic schemes. A comparison of results leads to conclude that both schemes can turn out to be complementary. The q-scheme yielding more detailed information that the semiclassic one as expected. © 2015 Wiley Periodicals, Inc.

Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials

The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation.

Radiated Electromagnetic Immunity Analysis of Flex Cable with Ground Plane Using Transmission Line Equations

This paper presents the analysis of radiated immunity of flex cable with ground plane using transmission line equations. The conformal mapping transformation technique and the integral equations are employed to extract the equivalent RLCG parameters for canonical types and complicated types of structures, respectively. The external electromagnetic field sources are modeled as equivalent voltage and current sources in the transmission line equations. After the equivalent circuit is obtained, the induced voltage is computed via the SPICE solver. Validation with case studies shows that the approach is capable of efficiently modeling the radiated electromagnetic interference to evaluate the immunity level of devices under test.

Construction of the Pauli–Villars-Regulated Dirac Vacuum in Electromagnetic Fields

Using the Pauli–Villars regularization and arguments from convex analysis, we construct solutions to the classical time-independent Maxwell equations in Dirac’s vacuum, in the presence of small external electromagnetic sources. The vacuum is not an empty space, but rather a quantum fluctuating medium which behaves as a nonlinear polarizable material. Its behavior is described by a Dirac equation involving infinitely many particles. The quantum corrections to the usual Maxwell equations are nonlinear and nonlocal. Even if photons are described by a purely classical electromagnetic field, the resulting vacuum polarization coincides to first order with that of full Quantum Electrodynamics.

Nano- and Biophotonics

Nanoand biophotonics is a multidisciplinary scientifically rising field connecting together chemists, material engineers, physicists, optical engineers, and biologists. The field has high academic as well as industrial significance involving development of various devices usable for data sensing and manipulation, for example, for optics communication, as well as monitoring techniques that may be applicable for detection of cancer and other common diseases. The papers accepted for publication in this special issue implement the above-mentioned general description while showing the capability of various scientific disciplines to be implemented for biophotonic and biomedical applications. In the paper entitled “Uniformly immobilizing gold nanorods on a glass substrates” the authors present a new technique for uniformly disposing gold nanorods and nanoparticles on glass substrate. This activity can be applicable for biomedical imaging and treatment applications in which the nanoparticles are used to backscatter the applied illumination or when they are heated by external electromagnetic or photonic source in order to kill cancer cells that are in proximity to the nanoparticles. In the paper entitled “An analytic analysis of the diffusive heat flow equation for different magnetic field profiles for a single magnetic nanoparticle” magnetic nanoparticles are being utilized to kill cancer cells. In this case the external magnetic field heats the nanorods and thereafter the cancer cells as well. The paper presents a physical modeling to the heat flow equation and numerically predicts the impact of the external magnetic field on the time-varying temperature of the nanoparticles. In the paper entitled “A self-powered medical device for blood irradiation therapy,” the authors present a novel biomedical treatment device based upon special pill that is powered due to the flow of blood in the veins. The pill is used to illuminate the blood vein internally thereby realizing blood irradiation therapy. The paper entitled “The effect of nanoparticle size on cellular binding probability” is once again aiming for biomedical applications in which nanoparticles are used to detect and cure cancer cells. The paper discusses the probability for the binding of the particles to such cells as a function of their size and dimensional proportions. The paper entitled “Integrated polypyrrole flexible conductors for biochips and MEMS applications” deals with the development and characterization of integrated polypyrrole flexible conductors. Such conductors can be used as part of biochips or as part of micro-electromechanical system (MEMS) devices for biomedical procedures.

Hybrid antenna–magnetoresistive sensor for radio frequency field detection

A self-powered, hybrid sensor integrating a resonant microfabricated antenna with a spin valve sensor was fabricated. The device was activated by a radio frequency (RF) external electromagnetic source. This hybrid device was designed to behave as a series resonant circuit at 130 MHz. The self-powered sensor (powered by the RF field through the antenna) was capable of measuring the amplitude of the perpendicular RF excitation field crossing the antenna, down to 2.5 μT when excited with a RF field of 130 MHz.

Self-powered, hybrid antenna-magnetoresistive sensor for magnetic field detection

A self-powered hybrid sensor integrating a resonant antenna with a magnetoresistive spin valve sensor was microfabricated. The device is activated by a radiofrequency (rf) external electromagnetic source. This hybrid sensor is capable of detecting dc and ac external magnetic fields in the thermal noise regime. For an excitation rf field of 17 dB m at 130 MHz, the sensitivity to a transverse magnetic field normalized by the current induced in the device was 812 V (T A)−1 for dc magnetic field detection and 918 V (T A)−1 for the ac field measurement.

Estimation of the interference coupling into cables within electrically large multiroom structures

Abstract. Communication cables are used to transfer data between components of a system. As a part of the EMC analysis of complex systems, it is necessary to determine which level of interference can be expected at the input of connected devices due to the coupling into the irradiated cable. For electrically large systems consisting of several rooms with cables connecting components located in different rooms, an estimation of the coupled disturbances inside cables using commercial field computation software is often not feasible without several restrictions. In many cases, this is related to the non-availability of computing memory and processing power needed for the computation. In this paper, we are going to show that, starting from a topological analysis of the entire system, weak coupling paths within the system can be can be identified. By neglecting these coupling paths and using the transmission line approach, the original system will be simplified so that a simpler estimation is possible. Using the example of a system which is composed of two rooms, multiple apertures, and a network cable located in both chambers, it is shown that an estimation of the coupled disturbances due to external electromagnetic sources is feasible with this approach. Starting from an incident electromagnetic field, we determine transfer functions describing the coupling means (apertures, cables). Using these transfer functions and the knowledge of the weak coupling paths above, a decision is taken regarding the means for paths that can be neglected during the estimation. The estimation of the coupling into the cable is then made while taking only paths with strong coupling into account. The remaining part of the wiring harness in areas with weak coupling is represented by its input impedance. A comparison with the original network shows a good agreement.

Double Bits Error Correction for Computational Grid with CRC

In grid system error during sending information due to devastating factors like external electromagnetic sources and noise is inevitable. The Cyclic Redundancy Check (CRC) method is used for error detection. CRC is used to control such factors in received information. In this paper, the new method based on CRC has been introduced that is able to detect the exact place of double bits error and correct them. In this method the receiver divide the received data on polynomial generator, g(x), and then get the remainder. Receiver can correct double bits error by comparing the remainder and the content of the look-up table. The result show that presented method can reduce the traffic for application that have low bit error rate (BER).