Transmission Loss Research Articles

Transmission Loss Characteristics of Dual Cavity Impedance Composite Mufflers for Non-Planar Wave Cavity Resonance

In conventional gasoline automobiles, the engine powers the air conditioning system and engine noise can somewhat mask the noise and vibration of the air conditioning system. In pure electric vehicles, however, the absence of an engine makes the air conditioning system’s noise more noticeable, concentrated in a limited frequency range at constant speeds. As a result, aerodynamic noise from the air conditioning system is a primary noise source in electric vehicles. Pipeline silencers are the main method for reducing this noise. The current silencer design uses plane wave acoustic theory but when cavity modal resonance occurs, the transmission loss error is relatively high. This article addresses the issue of non-planar wave cavity resonance, studying the cavity modal of a muffler using the finite element method to reveal the transmission loss under cavity mode resonance. A dual cavity expansion structure of an impedance composite muffler is proposed, with sound-absorbing materials placed in the cavity to enhance acoustic performance. The analysis of the transmission loss characteristics of the impedance composite muffler provides a theoretical basis for noise control in pure electric vehicle air conditioning systems.

Performance study of an optical modulator based on a funnel-shaped waveguide with tip-plasma effect

Electro-optical modulators play a crucial role in the field of optical communications; high modulation depth and low loss are used to qualify optical modulators. In this study, the tip-plasmon effect was utilized to improve the optical mode confinement and achieve a significant enhancement of the optical-graphene coupling. The evaluated modulator demonstrates robust performance characteristics, exhibiting a modulation depth of up to 8.5 dB/µm while sustaining a transmission loss of 2.3 dB/µm. Furthermore, the modulator operates with an energy efficiency of 4.36 fJ/bit and achieves a modulation bandwidth of 293 GHz, assuming a modulation length of 20 µm.

Multi-objective Approach for Dynamic Economic Emission Dispatch Problem Considering Power System Reliability and Transmission Loss Prediction Using Cascaded Forward Neural Network

This study addresses the significant problem of Dynamic Economic Emission Dispatch (DEED), a critical consideration in power systems from both economic and environmental protection viewpoints. Reliability stands as another vital facet, impacting maintenance and operation perspectives. The integration of Artificial Neural Network (ANN)-based transmission loss prediction into the DEED model is also essential to address specific limitations and enhance the overall performance of the dispatch process. Traditionally, the DEED model relies on a single B-loss coefficient to estimate transmission losses. While this approach simplifies calculations, it fails to account for the significant variations in demand that occur throughout the dispatch period and it leads to inaccuracies in loss prediction, especially in dynamic environments. Using a single coefficient, the model cannot adequately capture the complex, non-linear relationships between power generation, load, and transmission losses under different operating conditions. To overcome this limitation, this study introduces an ANN-based loss prediction method integrated into the DEED model and uses trained ANN to replace the process of finding B-loss coefficients during each dispatch period. This paper also introduces a strategy leveraging the multi-objective northern goshawk optimizer algorithm, characterized by a non-dominated sorting and crowding distance mechanism, to enhance DEED considerations incorporating reliability (DEEDR). This novel algorithm improves the solution space effectively, maintains high population diversity and enables an even distribution of individuals sharing the same rank in the objective space. The fundamental objective of this study is to balance fuel cost, emission, and system reliability in power system operations. Compared with a few existing multi-objective optimization algorithms, this study demonstrates superior performance in generating a series of non-dominated solutions. The experimental results highlight its competitive and potential as an efficient tool in the DEED and DEEDR problems, promising a synergistic coordination of economy, environmental protection, and system reliability benefits in power system management.

Experimental characterization of littoral atmospheric acoustics: Concurrent meteorological and acoustic observations.

The aim of this work is to describe a rich set of acoustic transmission loss observations that were completed in a coastal environment. The data library, enumerated in detail and publicly posted, is comprised of pitch-catch acoustic transmission loss measurements along with concurrent high spatial resolution meteorological observations. The meteorological parameters include near-surface temperature profiles, vertical wind speed profiles in the acoustic propagation direction, and significant wave height estimates. The acoustic source is positioned on an anchored vessel such that the first several hundred meters of the acoustic range is over open water with one microphone array positioned at the shore. A second microphone array is placed several hundred meters inland along the same source-to-receiver heading. The path between the two acoustic arrays is uniform salt marsh vegetation. Observations were made during seven sessions, which represent a variety of atmospheric conditions. That variety of conditions allows for some experimental generalizations about transmission loss as a function of meteorological observations. These include (1) the relationship between vertical effective sound speed profile and transmission loss, and (2) the variability of acoustic pressure with turbulence over time and elevation.

Low loss ridge waveguides on the hybrid single crystalline silicon and lithium niobate thin films

The hybridization of silicon (Si) thin film and lithium niobate (LN) thin film with remarkable properties, including the excellent optical properties of LN, excellent electrical properties and mature processing advantages of Si, can provide an important material platform for integrated photonic applications. In this work, a 4-inch single crystalline Si thin film wafer was prepared using wafer bonding, grinding and polishing techniques on LN thin film substrate. The films were characterized by using high-resolution transmission electron microscopy (HRTEM). The interplanar spacings and strain of Si film were calculated by analysis of high-resolution X-ray diffraction (HRXRD). Si ridge straight waveguides were fabricated on the hybrid thin films, and the transmission loss was 1.2dB/cm. The near-field mode distribution of the waveguide was investigated by combining FDTD (Finite-Difference Time-Domain) simulation and end coupling measurement.

Deciphering split ring resonators: understanding theoretical validation and simulation implications

This study presents a comparative analysis of analytical calculations and simulation results of a single-ring split ring resonator (SRR). A simulated SRR made of aluminum, designed in high frequency structure simulator (HFSS), with the resonant frequency of 3.97 GHz with transmission loss of −47.7 dB. The initial gap, width, and thickness of the ring are set at 1 mm, 1 mm, and 3 mm, respectively. These geometrical parameters are subsequently varied in simulations, and theoretical calculations are conducted for each variation using Python 3.10 code to facilitate comparative analysis. The analytical calculations reveal certain limitations in accurately modeling the impact of fringing and radiation, particularly when dealing with smaller dimensions. Although there exist slight disparities between the simulated and calculated outcomes, it is evident that the theoretically derived results exhibit a close correspondence with simulated responses, particularly for dimensions that are not excessively small. This observation underscores the confirmation that an augmentation in the gap of the Split Ring Resonator (SRR) leads to an elevation in the resonant frequency. Furthermore, by maintaining a constant inner radius and adjusting the outer radius to modulate the width of the SRR, a decrease in the resonant frequency is noted with an increase in the width of the metallic ring. Similarly, an increase in the thickness of the ring contributes to a reduction in the resonant frequency This comprehensive investigation provides a valuable methodology for corroborating theoretically derived results with simulation data. Additionally, the research underscores the diverse resonances that can be achieved by fine-tuning the gap, width, and thickness of the split ring resonator, highlighting the significance of selecting these dimensions carefully to attain specific resonant frequencies.

High and long-lasting antifogging performance of silane based hydrophilic polymer coating

The inevitable presence of fog causes a loss of light transmission in optical materials and leads to many unacceptable and serious consequences. A promising strategy for avoiding fog is to modulate the wettability of the material surface and further change the formed way of droplets. Although many works achieved high antifogging coatings, they are lack of the long-lasting antifogging at varied conditions. In this work, a high adhesion strength and persistent antifogging capability hydrophilic coating is obtained by utilizing silane coupling agents containing double bonds such as triethoxyvinylsilane (A151) and 3-(trimethoxysilyl)propyl methacrylate (KH570) with 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and then compositing with poly(vinyl alcohol) (PVA). The coating composed of A151 has a relatively uniform and flat surface structure, due to weaker hydrolysis ability of A151 promoted the smooth condensation speed, compared to KH570. Thanks to the hydrophilic and hydrophobic balance properties of the A151-modulated coating network, the resultant coating exhibits good antifogging performance in the range of 0 °C to 90 °C, which keeps a light transmission of about 85 %. Surprisingly, the coating shows excellent adhesion (350–700 kPa) to the substrate, which is significantly better than other conventional hydrophilic antifogging coatings, and the hydrophilic and hydrophobic modulation capability and the enhanced interfacial adhesion of A151 segments provide the basis of the coating for long-lasting antifogging, which would open up a new way of durable hydrophilic antifogging coatings.

Design of hollow-core anti-resonant optical fiber based on bragg elements with low-loss and wide bandwidth

A type of anti-resonant hollow-core optical fiber consisting of Bragg elements is proposed. The confinement and bending losses are numerically simulated using the finite element method. It is found that the introduction of concentric rings to form anti-resonant structure can reduce the mode transmission loss by 2 ∼ 4 orders of magnitude compared with the anti-resonant element composed of only one dielectric layer, therefore it can achieve ultra-low loss optical transmission. The influence of the structural parameters on the confinement loss was investigated. Furthermore, it is demonstrated that each dielectric layer independently contributes to the confinement of the core modes. It is also found that the Bragg reflection structure can effectively suppress the coupling between core and cladding modes, and achieve broadband low-loss optical transmission under small bending radius. In particular, it can achieve a low transmission loss of less than 0.1 dB km−1 over a wide wavelength range of 600 nm at the bending radius of 3 cm.

Projected Future Scenario of Electric Vehicles and Their Latent Impact on Electricity Demand in Kenya

Abstract-This study projects the future scenario of electric vehicle (EV) adoption and its impact on electricity demand in Kenya. Using data from the Kenya National Bureau of Statistics on EVs and internal combustion engine vehicles (ICEVs) registered from 2010 to 2022. Logistic growth model (LGM) used for projections was executed using MATLAB. The projected number of EVs by 2050 for conservative (25%) moderate (50%), optimistic (75%), and original (100%) adoption rates were respectively 3,927,131; 7,475,274; 9,880,293 and 10,807,843 with corresponding electricity demand of 14.8 TWh, 28.2 TWh, 37.3 TWh and 40.8 TWh, which increases to 18.7 TWh, 35.7 TWh, 47.2 TWh, and 51.6 TWh when generation and transmission losses are added. Adding electricity demand by other sectors, net electricity generation increases in the range from 37.4 TWh to 70.3 TWh for conservative and original scenarios respectively by 2050, which represent 3-times and 5.5 times the 2022-generation of 13 TWh. In conclusion, EVs penetration into the Kenyan market is currently low. However, their eventual replacement of ICEVs will have significant implications for electricity demand and supply, even under the conservative scenario. Key Words: transportation, electric vehicles, energy demand, logistics growth model, climate change

Acoustic optimization of a tee via a Helmholtz resonant cavity and noise prediction via a genetic algorithm coupled with the grey model

As a key local component in heating, ventilation and air conditioning (HVAC) systems, the acoustic characteristics of the tee largely determine the indoor acoustic environment quality. The aim of this study was to determine the impact of the Helmholtz resonant cavity (HRC) on the tee noise and sound transmission loss (STL). The noise was predicted using the Ffowcs Williams-Hawkings (FW-H) equation and large eddy simulation (LES), and an analysis was conducted on four design variables: the cavity width, cavity height, outlet flow ratio, and hole width. The results indicated that increasing the hole width had a positive effect on reducing the noise of the tee. HRC could result in a tee peak noise attenuation up to 34.81 dB. In addition, based on grey model (GM) and genetic algorithm (GA) theory, the noise of the Helmholtz resonant tee (HRT) was predicted, and a noise prediction formula for resonant cavity structure paraments was derived. This study provides a new perspective for optimizing the STL of the tee and a simplified prediction method for low-noise tee design.

A New Perspective on the Scattering Mechanism of S-Band Weather Radar Clear-Air Echoes Based on Communication Models

Clear-air echo studies are usually based on isotropic turbulence theory. But the theory has been considered incomplete by modern turbulence theory. The intermittence of turbulence can reveal obvious shortcomings in the existing studies of clear-air echoes. The mechanism of clear-air echo scattering needs to be supplemented. This paper introduces the troposcatter theory, normally used in over-the-horizon communication, to fill the gap left by Bragg scattering. By treating radar as a self-transmitted and self-received device, the equivalent transmission loss of weather radar is established and compared with the recommendations of the Radiocommunication Sector of the International Telecommunication Union (ITU-R). The results show that the S-band radar transmission loss aligns with ITU-R recommendations. There is also a linear regression relationship between the radar transmission loss and height, which conforms to the troposcatter theory. This means that the theory of troposcatter scattering is a supplement to the theory of Bragg scattering. Tropospheric scattering can be thought of as general Bragg scattering. Meanwhile, based on ITU-R recommendations, this study also provides a new way for the recognition of biological echoes.

Measurement of Resonant Frequency of Radio Frequency Converter under Conditions of Significant Electromagnetic Losses

The measurement of resonant frequency in radio wave converter under conditions of high electromagnetic losses presents a formidable challenge. This frequency serves as a crucial parameter directly linked to non-electronic quantities, such as spatial separation thresholds or substance consumption levels. Consequently, accurate measurement of these non-electric variables necessitates precise determination of the transmitter's resonant frequency. However, when electromagnetic losses escalate due to control environment properties, achieving such precision becomes daunting. Common methodologies often hinge on assessing resonant frequency via the transmitter's amplitude-frequency characteristic. However, conventional approaches, typically reliant on electron beam tubes with intricate control mechanisms, falter in accuracy amidst substantial electromagnetic transmission losses. This inadequacy undermines the efficacy of current devices. This paper introduces an unconventional method for resonance frequency measurement and underscores the benefits of the device developed through this novel approach compared to existing ones. The proposed method ensures sustained high measurement accuracy even in the face of significant transmitter electromagnetic losses. Central to this method is the measurement of frequencies ω₁ and ω₂ proximate to the resonant circuit's extreme value at points characterized by identical transmission coefficients. Resonant frequency is then determined as the half-sum of these frequencies during symmetrical frequency modulation. This innovative approach promises to overcome the limitations of traditional resonance frequency measurement methods, offering enhanced precision and reliability in challenging electromagnetic environments.

A global plasma and surface model of hydrogen/methane inductively coupled discharge to analyze hydrocarbon plasma–surface interactions in extreme-ultraviolet lithography machines

Hydrocarbon contamination is associated with light transmission losses in modern lithography machines, which contain extreme-ultraviolet-induced plasma. A volume-averaged global and deposition/etch surface model of a reference hydrogen/methane inductive discharge is developed to investigate the plasma–surface interactions. The simulation results are validated against a wide variety of experiments and verified with respect to multiple sets of computational data. The deposition rate is calculated for a variation in methane impurity (10–10 000 ppm), power, pressure, and net mass flow. The simulations conclude that the hydrocarbon plasma deposition can be minimized by reducing methane impurity and excluding solid organic structures.

Superhydrophilic antireflection films with excellent optical and mechanical performance for perovskite solar cells

SiO2-based antireflection (AR) films can obviously improve the transmittance of the glass cover on the solar cells. Nevertheless, it’s still challenging to fabricate SiO2 films in a facile way with great antireflective properties, high hardness and good weather resistance to ensure their long-term use in outdoor environments. To solve this problem, a double-layer broadband SiO2 antireflective film with high transmittance increase and excellent mechanical properties was successfully prepared via an acid-catalyzed sol–gel method using polyethylene glycol (PEG) as pore-forming agent. The porous PEG2000-modified SiO2 films were selected as the outer layer for coating onto the pure SiO2 film to form double-layer SiO2 films with graded refractive index. When the mass ratio of PEG2000 to TEOS was 40 %, the obtained film showed the highest transmittance increase of 3.03 % in the wavelength range of 380–1100 nm and a high hardness of 3H. After applied to the perovskite solar cell, a significant enhancement of 1.19 % in photoelectric conversion efficiency (PCE) was achieved compared to the solar cell covered with bare substrate. Furthermore, the water contact angle (WCA) was also reduced to 6° while that of pure SiO2 film was 51.3°, endowing the double-layer SiO2 film superhydrophilic and anti-fogging performance. After the weather resistance test, the transmittance loss of the film was only 0.38 %. Therefore, this work demonstrated that the use of an appropriate amount of pore-forming agent PEG and the double-layer graded refractive index structure can enhance the transmittance of acid-catalyzed SiO₂ films, while maintaining high hardness and good weathering resistance for perovskite solar cells.

Modelling of negative equivalent magnetic reluctance structure and its application in weak-coupling wireless power transmission

In weak-coupling wireless power transmission, increasing operating frequency, and incorporating metamaterials, resonance structures or ferrite cores have been explored as effective solutions to enhance power efficiency. However, these solutions present significant challenges that need to be addressed. The increased operating frequency boosts ferrite core losses when it exceeds the working frequency range of the material. Existing metamaterial-based solutions present challenges in terms of requiring additional space for slab installation, resulting in increased overall size. In addition, limitations are faced in using Snell’s law for explaining the effects of metamaterial-based solutions outside the transmission path, where the magnetic field can not be reflected or refracted. To address these issues, in this work, the concept of a negative equivalent magnetic reluctance structure is proposed and the metamaterial theory is extended with the proposed magnetic reluctance modelling method. Especially, the negative equivalent magnetic reluctance structure is effectively employed in the weak-coupling wireless power transfer system. The proposed negative equivalent magnetic reluctance structure is verified by the stacked negative equivalent magnetic reluctance structure-based transformer experiments and two-coil mutual inductance experiments. Besides, the transmission gain, power experiments and loss analysis experiments verify the effectiveness of the proposed structure in the weak-coupling wireless power transfer system.

Two-stage data-driven optimal energy management and dynamic real-time operation in networked microgrid based on a deep reinforcement learning approach

Given the significant challenges posed by the vast and diverse data in energy management, this study introduces a two-stage approach: optimal energy management system (OEMS) and dynamic real-time operation (DRTOP). These stages employ a multi-agent policy-oriented deep reinforcement learning (DRL) approach, aiming to minimize operating and energy exchange costs through interactions in the networked microgrid (NMG) energy market. The primary objectives include minimizing the distribution system operator (DSO) cost and optimizing the exchanged power between DSO and NMG, and the power transmission losses and the secondary include minimizing MG’s operating cost, optimal use of renewable energy resources (RER) and energy storage systems (ESS), minimizing the exchanged power cost with the main grid and, risk analysis. The OEMS&DRTOP model is developed based on the Stackelberg game theory and the DRL structure. The DRL model is developed in two offline learning and online distributed operation phases to minimize the computational burden, time, and DRL operation process. This study’s results show the high efficiency of the presented approach to minimizing the operating cost, the exchanged power based on the price uncertainty, power transmission losses, and, RER and ESSs optimal participation. In addition, regarding computational load, the proposed concept demonstrates a 12.9% reduction compared to the dueling deep Q-network method and a 17% reduction compared to the deep Q-network method. Also regarding computational time, the proposed concept demonstrates a 17.13% reduction compared to the dueling deep Q-network method and a 25.6% reduction compared to the deep Q-network method.

Direct ink writing of woodpile-kind alumina phononic crystals for MHz regime

We report comprehensive work on the fabrication of alumina-based phononic crystals (PhCs) using direct ink writing (DIW), measurement of anisotropic properties, and identification of acoustic bandgaps. Woodpile-structure-kind PhCs of characteristic size 1.1 mm and 10 periods were fabricated from alumina and polyvinyl alcohol (PVA) solution, and processed by freezing under vacuum. Next, the anisotropic elastic constants of alumina were obtained from bulk specimens using resonant ultrasound spectroscopy. Band diagrams and transmission loss were computed using the finite-element method and good correlations were found between the bandgaps estimated by these methods. Multiple partial bandgaps and several local resonances were observed in many directions for frequencies below 2 MHz. This work is the first step toward developing ceramic PhC using additive manufacturing methods for high-temperature applications.

Cell-Resolved PV Soiling Measurement Using Drone Images

The maintenance of photovoltaic (PV) power plants is of central importance for their yield. To reach higher efficiencies in PV parks, it is helpful to detect soiling such as dust deposition and to apply this information to optimize cleaning strategies. Furthermore, a periodic inspection of the PV modules with infrared (IR) imagery is of advantage to detect and potentially remove faulty PV modules. Soiling can be erroneously interpreted as PV module defects and hence spatially resolved soiling measurements can improve the results of IR-based PV inspection. So far, soiling measurements are mostly performed only locally in PV fields, thus not supporting the above-mentioned IR inspections. This study presents a method for measuring the soiling of PV modules at cell resolution using RGB images taken by aerial drones under sunny conditions. The increase in brightness observed for soiled cells under evaluation, compared to clean cells, is used to calculate the transmission loss of the soiling layer. Photos of a clean PV module and a soiled module for which the soiling loss is measured electrically are used to determine the relation between the brightness increase and the soiling loss. To achieve this, the irradiance at the time of the image acquisitions and the viewing geometry are considered. The measurement method has been validated with electrical measurements of the soiling loss yielding root mean square deviations in the 1% absolute range. The method has the potential to be applied to entire PV parks in the future.

Spatiotemporal Analysis of Sonar Detection Range in Luzon Strait

Sonar serves as a critical submarine detection apparatus for naval vessels, with its detection range forming the foundation of its overall performance in underwater surveillance. The Luzon Strait, in the eastern part of the South China Sea, presents a complex hydrographic setting that profoundly influences sonar performance, necessitating mastery of the detection range variation for enhanced anti-submarine operational efficiency. This study employs the Bellhop acoustic propagation model to estimate the transmission loss. Subsequently, a detection probability integration approach is applied to determine the sonar detection range in the Luzon Strait from 2019 to 2023, which is then subjected to statistical analysis. The findings indicate the following. (1) During the summer and autumn, the shallow mixed layer fails to generate a surface duct, resulting in shorter detection ranges that are primarily dependent on the water depth. In the Shallow Water Zone (<150 m), frequent interactions between sound waves and the sea boundaries lead to considerable acoustic energy attenuation, maintaining a short detection range. In the Intermediate Depth Zone (150–2500 m), sound rays retain adequate energy post-seabed reflection, extending the sonar detection to 5–8 km. Beyond 2500 m, the diminishing reflective energy restricts the range to 2–5 km. (2) Conversely, in the winter and spring, the formation of a surface duct becomes the predominant determinant of the detection range, capable of exceeding 10 km, overshadowing the influence of the water depth.

Modelling the Acoustic Properties of Baffles Made of Porous and Fibrous Materials

The research described in the article addresses the problem of measurement, prediction and practical use of the acoustic properties of materials determined in an impedance tube. The aim of the research was to develop a simple calculation model for the insertion loss of small machinery enclosures, based on the normal incidence sound transmission loss and the normal incidence sound absorption coefficient of porous and fibrous materials. Both experimental and model tests were carried out on materials such as mineral wool, melamine foam and rebonded polyurethane foam. Assessing the absorption properties of the tested porous and fibrous materials was performed using selected theoretical models, relating the calculations of the normal incidence sound absorption coefficient to measurements of this parameter conducted using an impedance tube. The application of the modified Allard and Champoux model brought the best results with the smallest discrepancies of the obtained results in relation to the experimental tests. Assessing the sound-insulating properties of the tested mineral wool was carried out using the proposed calculation model for the normal incidence sound transmission loss, relating the obtained results to measurements conducted using an impedance tube. The assessment of the sound-insulating properties of porous and fibrous materials was performed using the proposed calculation model for insertion loss, which was validated using two prototype test stands for determining the insertion loss of cubic enclosures, in this case with walls made of porous and fibrous materials. Satisfactory results were obtained for engineering applications in the calculation results using the proposed models with respect to measurements. The results may have practical applications in assessing the effectiveness of acoustic enclosures, in which the basic construction material is an appropriate porous or fibrous plate, selected to have both sound-absorbing and sound-insulating properties.