Energy Density Rate Research Articles

Influence of metasurface pit structure on the anti-glare performance of display glass via high-throughput calculation

Recently more and more attentions have been drawn on the anti-glare property of display glass, which is directly related to visual health. However, it is still a big challenge to study the influence of the micron-size metasurface structure on the anti-glare property of glass by way of experiment. In this work, an ideal micron-size metasurface filled with uniform pits was firstly established on the display glass via the theoretical simulation. By using FDTD solutions software, the influences of the diameter (D) and depth (L) of the pits on anti-glare properties, such as reflectance and transmittance, electric field intensity distribution, energy flow density distribution, maximum reflection angle and maximum refraction angle, were investigated detailedly. Results show that a small size (less than 6 μm) of pits can promote the anti-reflectance, transmittance and anti-glare property of display glass. Meanwhile, when the diameter of pits matched well with the depth, namely D = 1/L = 0.3–0.4 μm, or D = 3/L = 0.6–1.1 μm, the color brightness and contrast of display glass were improved largely. The equivalent reflectance and equivalent transmittance can also be calculated at the wavelength of 200–1200 nm by using contour cloud map to find the optimal diameter and depth with good anti-glare performance. The distribution of electric field intensity and energy flow density at the specific wavelength which is equal or close to the size of the pits also help to illustrate the flash point position, and the short-range anti-reflection effect and long-range diffuse reflectance effect of metasurface pit structure. Specially, when the diameter is 3 μm and the depth is 0.6 μm, the maximum reflection angle is 113.8°, the maximum refraction angle is 138.6°, the equivalent reflectance is 3.58%, and the glass shows excellent anti-reflection and anti-glare properties, which make the display glass more comfortable and colorful.

Angular momenta in fields from a rotational mechanical antenna‡ ‡JPCO-102088.R3, Submitted to J. Phys. D: Appl. Phys. on 13th May, transferred to J. Phys. Commun. 3rd August, revised 17th Nov. and 5th Dec., accepted 8th Dec. 2021.

Mechanic antennas provide opportunities for human portable, VLF communications, where a rotational dipole emits EM signals with angular momenta. In this paper we analytically derive the electromagnetic fields from a rotational electric dipole using Fourier transform method, and find that the radiated fields from the rotational electric dipole carries nonzero energy flow density in both orbital and spin angular momentum (AM) parts by their flux tensors. Intuitively, a dipole circulating on the transverse plane induces a longitudinal orbital angular momentum and a longitudinal spin angular momentum. And the binding force for the rotational electric dipole is then shown to result mainly from the Coulomb fields. We believe that our work will contributes to novel communication designs for portable mechanic antennas.

Anti-cavitation optimal design and experimental research on tidal turbines based on improved inverse BEM

To capture tidal current energy to the greatest extent possible, the turbines must to be large in-scale. When the turbine is close to the free surface, with high energy-flow density, unsteady cavitation on the blade surface has a large negative impact on the efficiency and life of the turbine. This paper presents a revised theoretical analysis of hydrodynamics optimization of horizontal-axis tidal turbines, including cavitation effects, based on improved inverse blade element momentum (BEM) theory. The cavitation performance is reflected by the minimum pressure coefficient peak value on the blade surface, based on which the cavitation prediction model is established. The cavitation prediction model and improved inverse BEM theory are combined; additionally, the mathematical model of multi-objective optimization is established. To verify the effectiveness of the proposed methodology, a 10-kW current turbine was designed, and computational fluid dynamics (CFD) was used to validate the hydrodynamics characteristics of the resulting turbine blades. The experimental model was designed according to the similarity theory, and a cavitation mechanism visualization experiment and a performance parameter test experiment were carried out in a cavitation water tunnel. The simulation and experimental results revealed that the proposed design method achieves the optimization goal.

Efficacy and safety evaluation of low-intensity extracorporeal shock wave therapy on prostatitis-like symptoms: An open-label, single-arm trial.

The present work aims to evaluate the clinical efficacy and safety of low-intensity extracorporeal shock wave therapy (Li-ESWT) on patients with prostatitis-like symptoms (PLS). Patients with PLS were recruited and received four-week Li-ESWT (once per week), which was conducted at a frequency of 3Hz with a preferred energy flow density of 0.25mJ/mm2 . The scores of the National Institute of Health Chronic Prostatitis Symptoms Index (NIH-CPSI), International Prostate Symptom Score (IPSS), International Index of Erectile Function (IIEF-5), and Visual Analogue Scale (VAS) were recorded to assess the remission of disease in the 0, 1st, 2nd, 3rd, 4th, 5th, 8th and 16th weeks. A decrease of the NIH-CPSI score ≥6 was regarded as the effectiveness standard of Li-ESWT. Among 91 enrolled patients, the scores of all validated questionnaires presented significant improvements in the 4th week (p<.05) compared with that in baseline, except for IIEF-5. The treatment effective rates in the 1st, 2nd, 3rd, 4th, 5th, 8th and 16th weeks were 28.57%, 38.46%, 47.25%, 51.65%, 57.30%, 68.18% and 69.44%, respectively. No pronounced undesirable side effect has occurred. Li-ESWT is effective and safe in treating PLS. The efficacy can be maintained within three months.

Influence of initial phase of polarization on tight focusing of vector beam

Generally, the influence of initial phase of polarization distribution of incident vector beams always is ignored in its tight focusing, because it just induce the whole rotation of polarization distribution. In this paper, we show some distinctive effects induced by the initial azimuthal phase of polarization distribution in the tight focusing of radially polarized and azimuthal-variant hybrid vector beams. For these two types of vector beams, the initial azimuthal phase of polarization distribution induces two types rotation, the whole polarization rotation and the combined polarization rotation including the polarization distribution rotation and phase difference rotation, respectively. Furthermore, two methods are presented for modulating energy flow density and spin angular momentum density in the focal region, the synchronous and asynchronous rotation, which denote two polarization unit vectors with the same or different initial phase. Our results indicate the light–matter interaction can be induced by the polarization distribution rotation of incident vector beams in its tight focusing, and provide a possible connection with the rotational Doppler effect of optical vector beams.

Numerical Analysis on the Performance of High Concentration Photovoltaic Systems Under the Nonuniform Energy Flow Density

Photovoltaic panels can directly convert solar energy into electricity, but temperature will have a certain impact on the efficiency of photovoltaic cells. Especially under the condition of nonuniform energy flow density of high-power concentration, it is of great significance to maintain the temperature uniformity of cells. Therefore, based on the radiation under nonuniform heat flux density, four heat exchangers were proposed: single-channel serpentine flow, multi-channel flat plate, full jet, and single-jet nozzle. Taking into account the uniformity of the cell temperature, the single-jet nozzle and single-channel serpentine flow can better maintain the uniformity of the temperature field compared with other heat exchangers. Especially under high-concentration energy flow density, considering the quality of heat and electricity, the performance of the four-jet nozzles is the best from the perspective of exergy efficiency. Under the condition of four-jet nozzles, the electrical efficiency and thermal efficiency of the cell can be maintained at about 29 and 62.5%, respectively, and the exergy efficiency of the system can reach 31%.

Sound radiation analysis with an enriched Timoshenko beam model based on second strain gradient theory

In this work, an enriched Timoshenko beam model describing non-classical bending and shear motion is employed to study its free wave propagation, frequency response, and sound radiation while considering the local behavior of its internal heterogeneity. The enriched Timoshenko beam model is established based on Mindlin’s Second Strain Gradient (SSG) theory, which can capture the long-range interactions between underlying micro-structures in the frame of continuum mechanics. Dispersive behaviors of non-classical bending waves, shear waves, and the extra evanescent waves appearing exclusively in the SSG theory model are analyzed. Then investigations are carried forward into the modal density of non-classical bending waves, shear waves, and energy flow through the enriched model. At last, the frequency response and sound radiation of the Timoshenko beam are studied using wave approach based on its multi-modes character. The resulting non-classical frequency response and radiation features are compared with the classical elasticity theory result, upon which, impacts of local behavior in complex media on the structural dynamics and radiation features are discussed. The role of local behavior is, among others, clearly shown in the frame of the non-classical structural behavior.

CuO@NiCoFe-S core–shell nanorod arrays based on Cu foam for high performance energy storage

Growing electroactive materials directly on a three-dimensional conductive substrate can effectively reduce the “ineffective area” of the electrode during the electrochemical reaction, increase the utilization rate of the material, and thus increase the energy density of the device. Using the network structure of the three-dimensional conductive substrate to design electrode materials with unique microstructures can also improve the stability of the materials. In this work, we obtained different copper-based materials on the copper foam (CF) by in-situ growth method, and designed an independent three-dimensional layered CuO@NiCoFe-S (CuO@NCFS) core–shell nanostructure composite material. CuO@NCFS exhibits excellent electrochemical performance, reaching a specific capacitance of 4551 mF cm−2 at a current density of 1 mA cm−2 with good cycle stability (94.2% after 5000 cycles). In addition, the asymmetric supercapacitor (ASC) uses CuO@NCFS as the positive electrode and rGO as the negative electrode, which can provide an energy rate density of 4.5 mW cm−2 at a high energy density of 99.9 μWh cm−2. The findings provide some insight into rational design of electrode materials for high performance energy storage.

A Framework for Low-Intensity Low-Frequency Ultrasound Neuromodulation Sonication Parameter Identification from Micromechanical Flexoelectricity Modelling

Low-intensity, low-frequency ultrasound (LILFU) has recently emerged as a promising technique to modulate non-invasively nerve activities at lower cost than other traditional and more-invasive neuromodulation methods. However, there is currently no consensus on the optimum sonication parameters to be used in LILFU applications, and most of the accepted ranges have arisen from trial-and-error approaches. Here we utilise a recently proposed micromechanics model of membrane flexoelectricity, a potential candidate for neuromodulation, and simulate action potentials/membrane polarisation triggered by acoustic pulses of different pulse frequencies, pulse magnitudes and duty cycles. Results reveal that, at constant duty cycles, increasing the transmit frequency increases the thresholds of both the pulse magnitude and the elastic energy rate density required to mechanically trigger an action potential, whereas at constant frequencies, increasing the duty cycle reduces both. The influence of transmit frequency is weakened at lower duty cycles. Our simulation results offer some guidance on the selections of sonication parameters used in LILFU for neurologic disorder treatments in the context of the flexoelectricity hypothesis.

Bone Marrow Edema Syndrome of the Foot Treated with Extracorporeal Shock Wave Therapy: A Retrospective Case Series

To determine the validity and safety of extracorporeal shock wave therapy (ESWT) in the treatment of bone marrow edema syndrome (BMES) of the foot. Twenty patients diagnosed as foot BMES in our Center were followed and treated by ESWT for 1 to 2 courses. The target of the ESWT treatment was the most obvious foot tenderness, or the most obvious part of bone edema on magnetic resonance imaging (MRI). One course of ESWT was 1 time/week, 5 times in total, with the shock wave energy flow density 0.18 mJ/mm2. The visual analog scale (VAS) and the American Orthopedic Foot and Ankle Society (AOFAS) scores of the foot were recorded before treatment, at 3 months after treatment and the last follow-up; the areas of BME before treatment and at the last follow-up were measured by the fat suppression MRI. Complications during treatment were also recorded. Twenty follow-up patients were obtained. Compared with the pretreatment, the patients had significant improvement in various indicators at 3 months after treatment (p < 0.01). The sagittal MRI at the last follow-up showed that the BME area decreased significantly (p < 0.01). Two patients developed transient erythema on their skin after treatment and alleviated after 2 days of rest. No serious complications were found during treatment. Our findings show that for patients with foot BMES, the use of ESWT treatment can effectively relieve local pain, improve the motor function of the foot and ankle. Two courses of treatment may be required for some patients.

Influence of prey condition and incubation method on mortality, growth and metabolic rate during early life history in lake sturgeon, Acipenser fulvescens

Environmental conditions during early life can have a profound impact on developmental trajectory and ultimately ecological fitness of individuals. Therefore, from a conservation perspective it is vital to understand the longer-term implications of early phenotypic development on survival. In this study, we examined the effects of temperature (maintained at 16°C or ambient river temperature), prey condition (live or dead Artemia) and incubation method (tumbling jar or natural hatching over substrate) on the routine or standard metabolic rate (RMR, SMR), maximum metabolic rate (MMR), factorial aerobic scope, energy density (ED), whole body triglyceride concentration (TG), growth and mortality rate of age-0 lake sturgeon. Our results demonstrated that fish fed live artemia had significantly lower ED, growth and high mortality rates than those fed dead artemia at 32 days post-fertilisation (dpf) (p < .001). However, at 133 dpf fish fed live artemia showed higher MMR and no difference in ED, TG and growth rate compared to those fed dead prey during early life history. The present study showed that inclusion of live prey at the onset of exogenous feeding may be considered to promote a more natural phenotypic development in larval lake sturgeon.

Strong spin–orbit interaction of photonic skyrmions at the general optical interface

Abstract Photonic skyrmions have applications in many areas, including the vectorial and chiral optics, optical manipulation, deep-subwavelength imaging and nanometrology. Much effort has been focused on the experimental characterization of photonic skyrmions. Here, we give an insight into the spin and orbital features of photonic skyrmions constructed by the p-polarized and s-polarized surface waves at an interface with various electric and magnetic properties by analyzing the continuity of chirality, energy flow and momentum densities through the electric and magnetic interface. The continuity of chirality density indicates that the photonic skyrmion has a property of the optical transverse spin. Most importantly, the continuity of energy flow and momentum densities results in four spin–orbit interaction quantities, which indicate the gradient of electric polarizability or permeability governs the spin–orbit interaction of photonic skyrmions and leads to the discontinuity and even the reversal of spin orientation through the optical interface. Our investigations on the spin–orbit properties of photonic skyrmions, which can give rise to the spin-dependent force and topological unidirectional transportation, is thorough and can be extended to other classical wave, such as acoustic and fluid waves. The findings help in understanding the spin–orbit feature of photonic topological texture and in constructing further optical manipulation, sensing, quantum and topological techniques.

Sharp V‐notches in viscoplastic solids: Strain energy rate density rule and fracture toughness

AbstractDifferent from Neuber's rule or Glinka's energy method which are always adopted to characterize the notch tip field under elastoplastic condition, in this paper, the strain energy rate density (SERD) rule is used for viscoplastic materials. In particular, based on the definition of generalized notch stress intensity factor (G‐NSIF) for sharp V‐notch in viscoplastic solids, the concept of SERD for sharp V‐notch in viscoplastic solids is presented. Subsequently, by taking as a starting point the SERD, the averaged strain energy density (SED) for sharp V‐notch in viscoplastic solids is derived with integration of time. The fracture toughness relation between sharp V‐notch specimens and crack specimen in viscoplastic materials is given based on the transformation of SERD. A numerical approach is presented to compute the SERD and SED based on finite element method. Some crucial comments on the G‐NSIF have been discussed. Some typical solutions for SERD and SED for sharp V‐notched specimens are investigated.

Microscopic mechanism of alternating oscillations in a microchannel pulse tube based on molecular dynamics

The non-equilibrium molecular dynamic simulation method was used to analyze the microscopic dynamics process of alternating helium oscillations in a micro-channel pulse tube (MPT). The driving force was provided by a sinusoidal speed piston. A reflect wall was adopted as the power source similar to high-frequency liner compressors. The MPT's instantaneous temperature, pressure, speed mass flow, and time-averaged temperature were statistically analysed. At the micro level, the curve of the MPT's instantaneous properties approximated sinusoidal function. There was an alternating oscillation process with asymmetric property distributions between the MPT's compression and expansion process and the space-time distribution of each parameter's properties were non-uniform. The expansion process had a larger axial pressure gradient than the compression process. The analytical results showed that when the forced oscillation time caused by the piston motion was shorter than the natural oscillation time, the acoustic wave's energy flow density was higher. The cycle's time had little effect on the temperature of the cold end under low charge pressure. When the inflation pressure was higher than 20 bar, the temperature at the cold end was more sensitive to the time. As the time decreased, the temperature at the cold end further decreased and the time-averaged temperature at the cold end increased as the charge pressure increased. The negative effect mainly came from the temperature disturbance during the expansion process. The pressure ratio increased as the time decreased and was not significantly affected by the charge pressure, but it could generate a larger temperature gradient in the MPT's axial direction. In summary, the use of different forms of heat exchangers and phase shifters at the warm end could release or recover extra acoustic power. MPTs with fixed operating modes and dimension parameters should have optimal frequency to obtain the lowest no-load temperature at the cold end. The simulation results improve the understanding of pulse tubes' cooling mechanisms and provide theoretical support for the optimal design of micro-channel pulse tube coolers.

Pain reduction realized with extracorporeal shock wave therapy for the treatment of symptoms associated with interstitial cystitis/bladder pain syndrome-A prospective, multicenter, randomized, double-blind, placebo-controlled study.

Extracorporeal shock wave therapy (ESWT) inhibited bladder inflammation and pain in preclinical studies. We assessed ESWT for the treatment of refractory interstitial cystitis/bladder pain syndrome (IC/BPS). This double-blind, randomized, placebo-controlled physician-initiated study enrolled 54 patients with IC/BPS. The patients were assigned to ESWT (N = 24; 2000 shocks, frequency of 3 Hz, and maximum total energy flow density 0.25 mJ/mm2 ) once a week for 4 weeks at suprapubic bladder area or placebo (N = 25; shock wave setting without energy transmission). The primary endpoint was the average changes in O'Leary-Sant symptom scores (OSS) between baseline and 4 weeks after treatment. Secondary endpoints included visual analog scale (VAS, 0-10) for pain, the average changes of variables in a 3-day voiding diary, and global response assessment of patient satisfaction. At 4 weeks posttreatment, both groups were associated with a statistically significant decrease in OSS and VAS pain scale. However, there were no difference in mean change between ESWT vs placebo groups. A significantly higher proportion of patients on ESWT responded as improved in the VAS ≥ 3 vs placebo (P = .035). At 12 weeks posttreatment, improvement in the VAS ≥ 3 was 57.1% vs 19.0% (ESWT vs placebo; P = .011). The finding was associated with an improvement in frequency - 1.0 ± 2.3 vs 0.7 ± 3.2 (ESWT vs placebo; P = .065). No significant adverse events were found in either group. A reduction in pain was discovered in this trial assessing ESWT in patients with IC/BPS but OSS, which was the primary outcome parameter, was not improved.

Propagation properties of self-accelerating rotating elliptical vortex wave packets in a quadratic index medium

The self-accelerating rotating elliptical vortex (SREV) wave packets which carry orbital angular momentum have been introduced and studied for the first time, to the best of our knowledge. The propagation properties of SREV wave packets in a quadratic index medium are investigated analytically. The numerical experiments on SREV wave packets have a good agreement with analytical solutions. Furthermore, the generation and manipulation of different SREV wave packet modes, which show temporal self-accelerating and transversal periodically rotating properties, are obtained by adjusting the cross phase coefficient and the elliptical factor. In addition, the evolutions of phase, energy flow and angular momentum density of SREV wave packets for different propagation distances are demonstrated to study more about the dynamic rotating properties. The SREV wave packets have numerous potential application in novel optical communications.

Study on capture power of the sealed-buoy wave energy converter in low energy flow density area

In order to achieve the conversion of the wave energy into electrical energy in low energy flow density sea areas in this paper, the capture power of the sealed-buoy wave energy converter (SBWEC) was investigated by dynamics methods of rigid bodies based on the hydrology data of Shandong Peninsula. The effect of buoy diameter on the response amplitude operator (RAO) was studied using frequency domain analysis method. The effect of buoy diameter on the instantaneous capture power and the effect of mooring angle on the pitch time domain response were studied using time domain analysis method. Results show that the pitch RAO is increased by 10.5 times from 8°/m to 93°/m with the decrease in buoy diameter. The maximum pitch time domain response and capture power are obtained in the SBWEC with the diameter 15m, mooring angle 45° and the slider mass 40 Kg. It is derived that the average capture power and wave energy conversion efficiency are 44.1 KW and 54.44% for the SBWEC in low energy flow density sea areas. Then, the relevant research results provide some reference for the design and utilization of wave energy converter in low energy flow density sea areas.

Paraxial propagation of the first-order chirped Airy vortex beams propagating in a quadratic index media

ABSTRACT We investigate the propagation of the first-order chirped Airy vortex (FCAiV) beams in a quadratic index media analytically by applying the Huygen-Fresnel integral. The intensity, the phase, the energy flow density, and the angular momentum density are investigated for different chirped parameters, decay factors and parameters related to the gradient refractive index. There is an inversion of the self-acceleration of the FCAiV beams during the propagation. The FCAiV beams propagating in the quadratic index media hold a periodic evolution. The focusing intensity, the intensity distribution, the centre of mass of the FCAiV beams can be controlled by choosing different parameters.

Ultrasonic guided wave detection of U-shaped pipeline

The guided waves in the elbow was analyzed using semi- analytical finite element method, which was used to calculate the dispersion curves, along with the vibration deformation and energy flow density distribution of the elbow cross-section. The L(0,1) mode guided wave was used to detect different defects in the U-shaped pipeline in experiment. The average experimental velocity of L(0,1) mode in U-shaped pipeline was between the theoretical velocities of the straight pipe and the elbow, due to the different velocities in the two parts. The detection sensitivity difference of L(0,1) mode guided wave to defects in intrados and extrados of the elbow was analyzed, the experimental result showed that the reflected signal amplitude of defect in extrados was significantly larger than the defect in intrados, which was consistent with the energy flow density distribution in elbow cross-section.

Condition Classification of Water-Filled Underground Siphon Using Acoustic Sensors.

Siphons have been widely used in water supply systems and sewage networks. However, it is difficult to implement non-destructive testing due to structural complexity and limited accessibility. In this paper, a novel condition classification method for water-filled underground siphons is proposed, which uses the acoustic signals received from acoustic sensors installed in the siphon. The proposed method has the advantages of simpler operation, lower cost, and higher detection efficiency. The acoustic wave forms in the siphons reflect on the system characteristics. Seven typical conditions of a water-filled underground siphon were investigated, and a series of experiments were conducted. Acoustic signals were recorded and transformed into acoustic pressure responses for further analysis. The variational mode decomposition (VMD) and the acoustic energy flow density were used for signal processing and feature extraction. The acoustic energy flux density eigenvectors were input to three different classifiers to classify the siphon conditions. The results demonstrate that the proposed acoustic-based approach can effectively classify the blockage and damage conditions of siphons, and the recognition accuracy of the proposed method is higher than 94.4%. Therefore, this research has value for engineering applications.