Dissipative Losses Research Articles

Third- and Second-Harmonic Generation in All-Dielectric Nanostructures: A Mini Review

Frequency conversion such as harmonic generation is a fundamental physical process in nonlinear optics. The conventional nonlinear optical systems suffer from bulky size and cumbersome phase-matching conditions due to the inherently weak nonlinear response of natural materials. Aiming at the manipulation of nonlinear frequency conversion at the nanoscale with favorable conversion efficiencies, recent research has shifted toward the integration of nonlinear functionality into nanophotonics. Compared with plasmonic nanostructures showing high dissipative losses and thermal heating, all-dielectric nanostructures have demonstrated many excellent properties, including low loss, high damage threshold, and controllable resonant electric and magnetic optical nonlinearity. In this review, we cover the recent advances in nonlinear nanophotonics, with special emphasis on third- and second-harmonic generation from all-dielectric nanoantennas and metasurfaces. We discuss the main theoretical concepts, the design principles, and the functionalities of third- and second-harmonic generation processes from dielectric nanostructures and provide an outlook on the future directions and developments of this research field.

Influence of the heat insulation layer on the thermally stressed condition of the facade wall

Abstract The temperature-stress state of the concrete facade wall with a window opening, which is the external enclosing structure of the room with a steel heating device, was investigated by the method of numerical modeling. Estimated studies were performed for winter period when the heating system of the building is functioning. According to the results of solving the system of equations of thermal stress and equation of thermal conductivity, the temperature distribution over the wall volume and distribution of normal and tangential stresses were determined. Areas of the wall where these stresses are maximum were identified. The research was performed for cases of both, absence and presence of a heat-insulating layer on the outer surface of the facade wall. From comparison of the results obtained for these two options, it follows that the external thermal insulation coating not only helps to reduce dissipative heat loss through the facade wall, but also reduces the absolute values of stresses in the concrete wall arising resulting from temperature deformations. In some cases, the sign of stresses changes from stretching (wall without external insulation) to compressive (wall with insulation).

Effect of TiO2 as Filler in NaCl: Possible Applications in Ionic Storage Systems

High dielectric capacitors are increasingly used for energy storage in sustainable nanotechnologies. Here, we observed large enhancement of dielectric constant by 3 order at frequency 1kHz with moderate loss when TiO2 is added as a filler in NaCl bulk matrix. The TiO2 nanoparticles are synthesized via sol gel process and is subsequently added in varying weight percentage x in the ionic matrix of NaCl, which is represented as TiO2(x)NaCl. The parameters like dielectric constant, dissipation Loss and ac conductivity are measured with varying fraction of TiO2 in frequency range less than 25 KHz. The steady increase of dielectric constant with increasing filler content at low frequency indicates percolation type behavior which accounts for the first dielectric peak at x= 50. The dielectric loss is found to be around 1 for x< 45 whereas it tends to increases with higher filler fraction. Moreover, the frequency dependent polarization in this composite system also accounts for hopping type behavior of mobile charge carriers contributed by TiO2 as confirmed from ac conductivity measurement. Further, the samples are characterized by X-ray diffraction and Field emission scanning electron microscopy in order to study the structure and morphology of the samples. Overall, TiO2 incorporation strongly improves the dielectric behavior of the ionic matrix at low frequency, making it suitable for super dielectric material (SDM).

Loss evaluation and aerodynamics investigation of an aggressive intermediate turbine duct under off-design conditions

To maximize the performance of the intermediate turbine duct (ITD) under off-design conditions, the loss generation in a one-half stage turbine was quantified using entropy generation and the global entropy generation rate. The numerical results solved by the unsteady Reynolds-averaged Navier–Strokes equations were first verified. Then, the aerodynamic losses within the high-pressure turbine stage were evaluated by efficiency loss under nine operating conditions composed of three rotor speeds and three rotor tip gaps. Finally, the disturbance modes caused by the upstream wake were captured by the dynamic mode decomposition method. Different from the influence of tip gaps, losses of the high-pressure turbine and the ITD are due to the swirl angle display an opposite trend. Under the influence of the interaction between the tip leakage flow and the shroud flow of the ITD, the viscous dissipation and turbulent dissipation increase with a larger tip gap owing to the dominant counter-rotating vortices and secondary flow occurring near the upstream of the ITD shroud. In addition, a large gap seems to enlarge the swirl component of the inflow angle, especially over 80% passage height, leading to greater dissipation losses in these areas. At the ITD inlet, two pairs of counter-rotating vortices at the shroud and the hub are, respectively, captured by the axial velocity mode. Large tip gaps enhance endwall vortices near the shroud and make the up vortex pairs merge into one pair.

Dissipative Quantum Feedback in Measurements Using a Parametrically Coupled Microcavity

Micro- and nanoscale optical or microwave cavities are used in a wide range of classical applications and quantum science experiments, ranging from precision measurements, laser technologies to quantum control of mechanical motion. The dissipative photon loss via absorption, present to some extent in any optical cavity, is known to introduce thermo-optical effects and thereby impose fundamental limits on precision measurements. Here, we theoretically and experimentally reveal that such dissipative photon absorption can result in quantum feedback via in-loop field detection of the absorbed optical field, leading to the intracavity field fluctuations to be squashed or antisquashed. Strikingly, this modifies the optical cavity susceptibility in coherent response measurements and causes excess noise and correlations in incoherent interferometric optomechanical measurements using a cavity. We experimentally observe such unanticipated dissipative dynamics in optomechanical spectroscopy of sideband-cooled optomechanical crystal cavitiess at both cryogenic temperature (approximately 8 K) and ambient conditions. The dissipative feedback introduces effective modifications to the optical cavity linewidth and the optomechanical scattering rate and gives rise to excess imprecision noise in the interferometric quantum measurement of mechanical motion. Such dissipative feedback differs fundamentally from a quantum nondemolition feedback, e.g., optical Kerr squeezing. The dissipative feedback itself always results in an antisqueezed out-of-loop optical field, while it can enhance the coexisting Kerr squeezing under certain conditions. Our result has wide-ranging implications for future dissipation engineering, such as dissipation enhanced sideband cooling and Kerr squeezing, quantum frequency conversion, and nonreciprocity in photonic systems.

Experimental Demonstration of Dark‐State Metasurface Laser with Controllable Radiative Coupling

AbstractLasing at the nanoscale using plasmonic nanoparticles offers the prospect of strong field concentration, hence strong light−matter interactions, low lasing thresholds, and ultrafast operation. However plasmonic nanoparticles suffer from high dissipative and radiative losses, the latter being rigidly tied to the shape of the nanoparticles and symmetry of their localized plasmon resonant modes. To overcome this limitation, recent theoretical work proposes using direct lasing into dark surface states to construct lasers that conceptually allow for independent implementation of the lasing state and its coherent radiation output. Here, lasing in dark resonant states of a metasurface laser and controllable coherent outcoupling of radiation with the aid of a tightly coupled, weakly radiative metasurface are demonstrated experimentally. The laser is implemented using a thin, low‐loss dielectric film supporting surface mode‐like dark dielectric bound states and the coupling metasurface is composed of small non‐resonant scatterers that controllably but weakly perturb the dark mode and turn it partially bright. Distinct far‐field signatures that can be observed experimentally for both dark and bright lasing are identified and demonstrated. The scalability of this design, here implemented for lasing in the near‐infrared, enables large‐aperture ultra‐thin coherent light sources with controllable emission from the infrared to the visible.

Ultranarrow perfect absorber with linewidth down to 1 nm based on optical anapole mode

This paper is investigated a silicon-dielectric-metal nanostructure, it supports the optional anapole mode due to the destructive interference between electric and toroidal dipoles. Such the proposed nanostructure exhibits a near-perfect ultra-narrow absorption spectrum in the near infrared region with the absorption bandwidth (FWHM) of 0.48 nm and a high-quality (Q) factor up to 1763. Besides inherently low dissipative losses and strong anapole response, this optical nanostructure can demonstrate subtle refractive index sensing properties. Our work shed new light on active ultra-narrow band perfect absorption based on the optical anapole mode, and provides potential applications such as optical sensors, narrow-band filter, non-radiative data transmission and biomolecules manipulation.

An ultra-thin ventilated metasurface with extreme asymmetric absorption

Recent progress in minimizing sound absorbers is driven by their great scientific significance and engineering value; however, compact devices for low-frequency sound are still challenging. Here, we construct an ultra-thin metasurface by parallel connecting resonators with high dissipation loss to a non-resonant reactance-dominated boundary (RDB) with high radiation loss, which realizes extreme absorption asymmetry at the exceptional point of scattering eigenvalue. We develop a parallel transfer matrix method to design the system, and a deep-subwavelength absorber (the operating wavelength is 120 times of its thickness) with 99.2% and 0.5% absorption for sound incident from opposite ports is achieved. The extreme absorption asymmetry is ascribed to the distinct coupling between the RDB and resonant meta-atom in an unbalanced dissipating state with excellent robustness against geometrical reconfigurations originated from the broadband near-unity reflection characteristics of the RDB. In particular, the proposed strategy brings the design of a degree of freedom rather than typical multiple resonant modes, and an extensible prototype showing &amp;gt;90% (&amp;lt;1%) absorptance for left- (right-) incidence within a wavelength from 23.3 to 18 times its thickness is demonstrated.

A multi-objective regenerative braking control strategy combining with velocity optimization for connected vehicles

Deceleration is unavoidable owing to the traffic lights or obstacles during driving, which lead to great energy dissipation. To promote energy utilizing efficiency, regenerative braking is applied to convert kinetic energy into electricity. Previous researches about regenerative braking concentrate on the braking torque allocation optimization, which is undoubtedly important. Moreover, the control performance can be further improved combining with velocity optimization. With the emerging Connected Vehicle Technology, environmental information is available for vehicles. Therefore, the terminal braking distance and terminal velocity can be derived utilizing the information. Then a multi-objective regenerative braking control strategy based on the pesudospectral method is proposed with the terminal constraints. The control strategy optimizes both the velocity and braking torque allocation to reduce the energy dissipation and battery capacity loss simultaneously. Simulations are carried out under a speed bump scenario. Pareto front is obtained with different weights of the objectives and then analyzed to reveal the tradeoff between energy recovery and battery health, which assists in finding a desired balanced solution. Two representative Pareto optimal solutions are selected for comparison: the energy recovery priory strategy and the energy-life tradeoff strategy. Compared with the energy priory strategy, the energy-life tradeoff strategy decreases the battery capacity loss by 60.65%, but it leads to a 36.07% reduction in the energy recovery.

Effect of Iodine-doping toward ZnO critical optical constants and their applications to latent fingerprints detection

The present work focus on the influence of Iodine (I) doping on the improvement of properties of ZnO such as structural, optoelectronic, optical, dielectric and transport. I-doped ZnO materials were synthesized via an easy sol gel method assisted by microwave post-heated treatment. I doping level was 0, 0.025, 0.050, 0.075, and 0.100 at% with respect to Zn content. The deducted physico-chemical properties were based on XRD, Raman spectroscopy, EDS, XPS, SEM imaging, photoluminescence (PL) and UV-Visible diffuse reflectance (UV-Vis DRS) spectroscopy. The prepared nanomaterials were applied to latent fingerprints detection. The determined optical constants were based on diffuse reflectance data and consequently the refractive index and extinction coefficient. Tauc’s equation was used to evaluate both band gaps and inter-band transitions as impacted by doping. The dielectric properties, optical and electrical conductivities dependence on both frequencies and I-doping level were studied. Dissipation loss factors including surface and bulk contributions were evaluated. The dynamics of transport with the consideration of the four components dielectric relaxation time (τ), optical resistivity (ρopt), optical mobility (μopt), and optical charge carriers (Nopt), were discussed in terms of photons energy assessment and materials composition. The optical covalency and optical electronegativity modification were considered. IxZnO nanomaterials were applied successfully to fingerprint detection on various substrates such as glass surfaces, coins, and plastic sheets. Both I0.025ZnO and I0.1ZnO materials were identified as a potential candidate for forensic application.

Characterization of Low-Loss Dielectric Materials for High-Speed and High-Frequency Applications.

In this study, the Df (dissipation factor or loss tangent) and Dk (dielectric constant or permittivity) of the low-loss dielectric material from three different vendors are measured by the Fabry–Perot open resonator (FPOR) technique. Emphasis is placed on the sample preparation, data collection, and the comparison with the data sheet values provided from vendors. A coplanar waveguide with ground (CPWG) test vehicle with one of these raw dielectric materials (vendor 1) is designed (through Polar and simulation) and fabricated. The impedance of the test vehicle is measured by TDR (time-domain reflectometer), and the effective Dk of the test vehicle is calculated by the real cross-section of the metal line width, spacing, and thickness of the test vehicle and a closed-form equation. In parallel, the insertion loss and return loss are measured with the VNA (vector network analyzer) of the test vehicle. Finally, the measurement and simulation results are correlated. Some recommendations on the low-loss dielectric materials of the Dk and Df are also provided.

Spectra of Internal Friction in Polyethylene.

The study of spectra of internal friction and temperature dependencies of frequency of freely damped oscillatory process excited in investigated samples of polyethylene with different degree of crystallinity in the temperature range from −150 C to +150 C. It is established that four local dissipative processes of different intensity shown in different temperature intervals are observed on the spectra . These are , , , processes. The theoretical analysis of the relationship between the anomalous changes of the vibrational process frequency and the shift modulus defect and the internal friction mechanisms for each of the dissipative loss processes detected on the spectrum is carried out. The influence of supramolecular structures on local dissipative process in polyethylene is estimated.

Highly electric field enhancement induced by anapole modes coupling in the hybrid dielectric–metal nanoantenna

Plasmonic nanoantenna has received tremendous attention in various optoelectronic applications owing to their unique optical characteristics with strong localized electric field enhancement. However, the highly intrinsic dissipation losses of metallic nanoantennas limits its application development. Coupling anapole modes of dielectric nanostructure with plasmonic mode of metallic nanoantenna seems to provide a promising alternative to further boost the electric field intensity with low dissipation losses. Herein, we demonstrate that the electric field intensity from a metallic nanoantenna can be remarkably heightened through introducing a dielectric nanostructure to build hybrid dielectric–metal nanoantenna, where the hybrid nanoantenna is composed of a gold nanorod dimer and a slotted silicon nanodisk. Through rationally optimizing the structural parameters, the hybrid nanoantenna exhibits an intensified resonant electric field intensity (> 3700 folds) at the gap of the dimer nanoantenna, which exceeds 30 times higher than that of the individual dimer nanoantenna. The far-field scattering characteristics and the near-field electromagnetic field distributions are systematically investigated to elucidate the field enhancement mechanism via utilizing numerical simulations and multipole decomposition analysis. It can be confirmed that the highly electric field intensity can be primarily attributed to the mode coupling between plasmonic resonances of Au nanoantenna and the radiationless anapole modes supported by the slotted Si nanodisk. The proposed hybrid dielectric–metal nanoantenna can serve as an effective platform to amplify the radiative decay rate and Raman scattering intensity, which paves a prospective avenue in the field of single-molecule surface enhanced spectroscopy.

Time‐averaged and instantaneous magnetic loss characteristics of different products of electrical steel for frequencies of 16 2/3 Hz up to 500 Hz

Traditionally, products of electrical SiFe steel are focussed on applications for frequencies of 50–Hz. However, the recent developments of electric drive systems yielded a strong extension of the range from f = 16 2/3 Hz up to ca. 500 Hz. In spite of high industrial relevance, the literature offers the corresponding data on the material’s magnetic energy losses in very rare ways. This paper reports a first comparative, multi-parametric study on eight different steel products that comprise non-oriented steels (NO), grain-oriented steels (GO) and scribed grain-oriented steels (SGO). Consistently at IEC-standardized samples, they were analysed for the whole frequency range that was split into low frequency (LF) and medium frequency (MF), with 80 Hz as the border. Data is presented on time-averaged total losses P, on the corresponding hysteresis losses PH and eddy current losses PE. LF proved to be governed by PH and MF rather by PE, however, with strong variations. Further, instantaneous magnetization power functions p(φ) were determined for basic insights into the involved temporal developments of energy dissipation. GO-steels yielded profiles close to rectified co-sinus functions that can be fully attributed to dissipative losses. On the other hand, p(t) of NO-steels and SGO-steels prove to include negative segments that reflect potential energy power, in the course of alignments of atomic moments in instants of high induction. Examples of industrial relevance of the accumulated data are steel production technology, product categorization, failure tracing and energy conversion.

Theoretical Study of Potential Manufacturing Insulation Defects in Medium–Voltage Traction Motors

Medium-voltage motors dedicated to the applications of traction operate in an environment with strong multi-physics constraints. Electrical insulation of these engines is a complex multi-layered impregnated system which requires a given number of steps during the manufacturing process. In the present study, we theoretically investigated the potential manufacturing insulation defects of traction motors in low frequency domain. The aim is to assess the theoretical ability of dielectric spectroscopy method for the detection of these defects and the extension of the method to others insulation systems. The theoretical study is based on numerical modelling and simulation achieved by using Comsol Multiphysics software. In our numerical modelling the properties of the main dielectric elementary materials are frequency–dependent. The identification of each potential defect is carried out by comparing its equivalent capacitance and dissipation loss spectra with the characteristics of insulation without defect. As the results, all artificial defects are identifiable with a specific relative deviation. The detection of all the defects analysed will need a measuring device with resolution of 0.4%. Keywords—AC electric motors, Capacitance, dielectric, dissipation factor, composite insulation, numerical modelling.

Energy conversion performances during biomass air gasification process under microwave irradiation

Biomass gasification technology under microwave irradiation is a new and novel method, and the energy conversion performances during the process play a guiding role in improving the energy conversion efficiencies and developing the gasification simulation models. In order to improve the energy utilization efficiency of microwave biomass gasification system, this study investigated and presented the energy conversion performances during biomass gasification process under microwave irradiation, and these were materialized through detailing (a) the energy conversion performance in the microwave heating stage, and (b) the energy conversion performance in the microwave assisted biomass gasification stage. Different forms of energies in the biomass microwave gasification process were calculated by the method given in this study based on the experimental data. The results showed that the useful energy (energy in silicon carbide (SiC), 18.73 kJ) accounted for 31.22% of the total energy input (electrical energy, 60.00 kJ) in the heating stage, and the useful energy (energy in the products, 758.55 kJ) accounted for 63.41% of the total energy input (electrical and biomass energy, 1196.28 kJ) in the gasification stage. During the whole biomass gasification process under microwave irradiation, the useful energy output (energy in the products, 758.55 kJ) accounted for 60.38% of the total energy input (electrical and biomass energy, 1256.28 kJ), and the energy in the gas (523.40 kJ) product played a dominate role in product energy (758.55 kJ). The energy loss mainly included the heat loss in the gas flow (89.20 kJ), magnetron loss (191.80 kJ) and microwave dissipation loss (198.00 kJ), which accounted for 7.10%, 15.27% and 15.76% of the total energy, respectively. The contents detailed in this study not only presented the energy conversion performances during microwave assisted gasification process but also supplied important data for developing gasification simulation models.

Simultaneously tracing the fate of seven metals at a global level with MaTrace‐multi

Keeping materials in use for a long time is key to reducing primary material demand and environmental impacts of resource use. Recycling yields of metals should only be limited by thermodynamically unavoidable losses of the remelting processes for well-defined scraps. In practice, however, additional dissipative losses for metals occur due to incomplete collection of end-of-life products, insufficient waste sorting, remelting of contaminated or diluted scrap, and the downcycling of secondary materials. Here we simultaneously trace the fate of Al, Cr, Fe, Ni, Cu, Zn, and Pb in MaTrace-multi, a planetary dynamic material flow system. Metals pass the processes mining, fabrication, use-phase, collection, sorting, scrap allocation, remelting, and secondary material allocation. We calculate the circularity and longevity of the cohort of metal requirements for the final demand of 1 year. Nickel is found to have the best longevity at 116 (78 to 205) years, whereas zinc only has a longevity of 47 (37 to 61) years. While nickel, on average, is used in 5.13 (3.45 to 8.78) applications before dissipation, zinc is used only in 1.94 (1.52 to 2.47) applications. Our study results can be used to model the impacts of circular economy policies and technological developments on global metal cycles beyond the scope of studies modeling one metal at a time. This article met the requirements for a Gold–Gold JIE data openness badge described at http://jie.click/badges

Amount of dissipative energy loss when assessing left ventricular dysfunction in female patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is associated with an increased risk of cardiovascular disease. The purpose of the current study was to explore the amount of energy loss (EL) using vector flow mapping (VFM) in the detection of early stage left ventricular (LV) dysfunction among patients with SLE. Eighty-nine patients with SLE and fifty-six healthy controls were enrolled. SLE patients were further divided into inactive (SLEDAI ≤ 4, n = 43) and active (SLEDAI ≥ 5, n = 46) subgroups. A prosound F75 echocardiography machine was used for echocardiographic examination. Intra-cardiac flow images were analysed by a VFM workstation. Compared with the healthy group, the inactive SLE group had increased diastolic EL values (38.05 mW/m vs. 33.02 mW/m, p = 0.010). However, the systolic EL values were comparable between the inactive SLE group and the control group (26.07mW/m vs 23.15 mW/m, p = 0.105). The active SLE group exhibited significantly higher diastolic (104.13mW/m vs 33.02mW/m, p < 0.001) and systolic (48.83 mW/m vs 23.15mW/m, p < 0.001) EL values than the control group. The most notable correlation was observed between the values of the diastolic EL and SLEDAI in the inactive SLE group (r = 0.633, p < 0.001) and in the active SLE group (r = 0.824, p < 0.001). LV-dissipative EL assessed by using VFM is useful and feasible for estimating lesions of LV systolic and diastolic function in active SLE patients with preserved left ventricular ejection fraction. Increased disease activity may lead to increased risk of LV dysfunction.

Моделирование спектров поглощения пленок для нахождения их оптических констант

Achieving the maximum potential range, effective contrast transmission and obtaining images characterized by a higher signal-to-noise ratio is achieved in vision systems with optical antennas, which are characterized by a transparency coefficient close to the maximum. Often such systems use coherent illumination and infrared sources to obtain an image. The technical implementation of optical systems designed to work in systems of this type requires the development of antireflection and protective coatings of interference type. The quality of their synthesis is based on solving the problem of finding optical constants, especially for films for which there are dissipative energy losses in the considered part of the spectrum. The search for film constants using the spectrophotometric measurement method is complicated by the ambiguity of the procedure for analyzing spectrophotometric spectra. In this paper, a technique is used to minimize the errors of such an analysis. It is based on the correction of film spectra taking into account dissipative losses characterized by an absorption coefficient. Correction of the spectra is carried out by using an absorbing film model. The influence of the model shape on the accuracy of correction of absorption spectra is calculated. This technique allowed us to obtain the frequency dependences of the optical constants of BaMgF4 films at wavelengths from 1.3 to 27 microns.

Analytical regularities of inversionless superradiance

The article reports the results of a theoretical study of superradiance of three-level optical systems with a doublet in the ground state (Λ-scheme) placed in a high-quality cavity. Hyperbolic chaos and unpredictable dynamic movements of the system appear on the surface of a multidimensional torus without dissipative losses in the conditions of superradiance without population inversion. The study resulted in the development of conservation laws to reduce the dimension of the phase space. An analytical result is obtained for the special case of a degenerate doublet.