Transmission Energy Loss Research Articles

Dynamic Characteristics Analysis of the DI-SO Cylindrical Spur Gear System Based on Meshing Conditions

The dual-input single-output (DI-SO) cylindrical spur gear system possesses advantages such as high load-carrying capacity, precise transmission, and low energy loss. It is increasingly becoming a core component of power transmission systems in maritime vessels, aerospace, marine engineering, and construction machinery. In practical operation, the stability of the DI-SO cylindrical spur gear system is influenced by complex excitations. These excitations lead to nonlinear vibration, meshing instability, and noise, which affect the performance and reliability of the entire equipment. Hence, the dynamic performance of the DI-SO cylindrical spur gear system is thoroughly investigated in this research. The impact of excitations and nonlinear factors on the dynamic characteristics was investigated comprehensively. A comparative analysis of the gear system was conducted by establishing a bending–torsional coupling vibration analysis model under synchronous and asynchronous meshing conditions. Nonlinear factors such as periodic time-varying meshing stiffness, meshing damping, friction coefficient, friction arms, load sharing ratio, comprehensive transmission error, and backlash were considered in the proposed model. Then, the effect laws of excitations and nonlinear factors such as meshing frequency, driving load fluctuation, backlash, and comprehensive transmission error were analyzed. The results indicate that the dynamic characteristics exhibited staged stable and unstable states under different meshing frequencies and meshing conditions. At the medium-frequency meshing stage (0.96 × 104~1.78 × 104 Hz), alternating phenomena of multi-periodic, quasi-periodic, and chaotic motion states were observed. Moreover, the root mean square value (RMS) of the dynamic transmission error (DTE) in the asynchronized gear system was generally higher than that in the synchronized gear system. It was found that selecting the appropriate meshing condition could effectively reduce the amplitude of the DTE. Additionally, the dynamic performance could be significantly improved by adjusting control parameters such as driving load fluctuation (0~179 N), backlash (0.8 × 10−4~0.9 × 10−4 m), and comprehensive transmission error (7.9 × 10−4~9.4 × 10−4 m). The research results provide a theoretical guidance for the design and optimization of the DI-SO cylindrical spur gear system.

Wind Farms’ Location and Geographical Proximity as a Key Factor in Sustainable City Development: Evidence from Poland

In this study, the potential impact of wind farm locations on the sustainable development of cities in Poland was evaluated, considering the availability of wind-generated electricity. We analyzed 37 cities in Poland with populations over 100,000. Research indicates that wind farms located 30–80 km from large cities perform best in terms of generating capacity, while greater distances increase transmission costs and energy losses. In Poland, wind farms are primarily situated in the northwestern regions, posing challenges for energy transmission to the southern cities, which are the main centers of energy consumption. The findings show that wind farms with the highest generating capacity are generally about 50 km from major cities. Key factors influencing wind farm locations include technical criteria, economic feasibility, environmental impact, public opinion, and the availability of transmission networks. Sustainable development of wind farms requires strategic cooperation between urban and rural municipalities, joint spatial planning, coordinated land acquisition, and the exchange of know-how.

The low-frequency bandgap characteristics of phononic crystal isolators with multi-hole

A vibration isolator for a floating slab track, based on a locally resonant phononic crystal, has been designed to suppress vibrations caused by the wheel-rail interaction. In this isolator, a circular vibrator is connected to a connector through a rubber layer uniformly embedded in holes. The finite element method is utilized to compute the energy band structure and transmission loss of the vibration isolator, while the mechanism of bandgap is elucidated through the analysis of modes. The static stiffness and dynamic stiffness of the vibration isolator are calculated, which proves that the vibration isolator meets the requirements of engineering applications. The influence of the number of circular holes and the geometric parameters of the vibration isolator on the bandgap is examined. It is discovered that augmenting the number of holes and the hole diameter in the rubber layer leads to a decreased bandgap. A low-frequency locally resonant bandgap of 38.2–97.1 Hz and a relative bandgap bandwidth of 86.9 % are obtained by optimizing the vibration isolator. The vibration isolation performance of a floating slab track equipped with vibration isolators is analyzed and more robust vibration attenuation performance is obtained in the bandgap. The multi-hole phononic crystal vibration isolator is employed in floating slab tracks for rail transportation, effectively mitigating vibrations transmitted to tunnels, thus further minimizing the effects on the surrounding environment.

Probing atmospheric waves and the middle atmosphere dynamics using infrasound

Infrasound is defined as pressure fluctuations with frequencies between acoustic cut-off (5 min) and human-hearing frequency threshold of sound (16 Hz). Low-frequent infrasonic waves can travel long distances, ranging from hundreds to thousands of kilometres. The middle atmosphere dynamics mainly control the presence of atmospheric waveguides where energy transmission loss is low. These properties are utilized to record atmospheric explosions at highly sensitive pressure sensors (micro-barometers). A global network of 60 infrasound stations was designed as part of the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty. IMS infrasound stations can record small pressure fluctuations of a few millipascals, which can originate from numerous atmospheric infrasound sources, including meteorological phenomena. In this study, the capability of IMS infrasound arrays for capturing a broad spectrum of atmospheric wave phenomena is highlighted; for instance, mountain-associated infrasonic waves show features that seem to be correlated with orographic gravity waves. Moreover, the interaction of ocean waves produces quasi-continuous infrasound, so-called microbaroms. Infrasonic signatures from microbaroms can be used for probing the middle atmosphere dynamics and assessing atmospheric circulation models. For opening the unique global infrasound network of the IMS for meteorological applications, we also present open-access BGR infrasound data products of two decades and highlight selected case studies.

Subsurface acoustic ducts in the Northern California current system.

This study investigates the subsurface sound channel or acoustic duct that appears seasonally along the U.S. Pacific Northwest coast below the surface mixed layer. The duct has a significant impact on sound propagation at mid-frequencies by trapping sound energy and reducing transmission loss within the channel. A survey of the sound-speed profiles obtained from archived mooring and glider observations reveals that the duct is more prevalent in summer to fall than in winter to spring and offshore of the shelf break than over the shelf. The occurrence of the subsurface duct is typically associated with the presence of a strong halocline and a reduced thermocline or temperature inversion. Furthermore, the duct observed over the shelf slope corresponds to a vertically sheared along-slope velocity profile, characterized by equatorward near-surface flow overlaying poleward subsurface flow. Two potential duct formation mechanisms are examined in this study, which are seasonal surface heat exchange and baroclinic advection of distinct water masses. The former mechanism regulates the formation of a downward-refracting sound-speed gradient that caps the duct near the sea surface, while the latter contributes to the formation of an upward-refracting sound-speed gradient that defines the duct's lower boundary.

PROPOSALS TO IMPROVE THE INFORMATION CAPABILITIES OF COASTAL-BASED RADAR STATIONS FOR SURVEILLANCE OF SURFACE AND AIR OBJECTS

Sea-based radar stations (RS) are widely used for solving the tasks of radar surveillance of surface objects (SO) and air objects (AO). The subject of the article is the mechanisms of radio wave propagation in the boundary layer of the atmosphere. The aim is to investigate the possibilities of improving the accuracy of measuring the range and radial velocity of SO and AO observed beyond the line-of-sight of coastal-based RS. Objective: to analyse the spatial and temporal parameters and properties of waveguide layers above the water surface. Methods used: maximum likelihood and frequency. The following results were obtained. The results of experimental studies of seasonal and daily changes in the parameters of the lower troposphere layer in the Black Sea coastal zone and the parameters of tropospheric radio waveguides are presented. The procedure for calculating the energy transmission losses during radio wave propagation in the boundary layer of the atmosphere is presented, and the conditions for detecting SO and AO beyond the radar line-of-sight are determined. Recommendations for increasing the range of detection of SO and AO are given, which are associated with the possibility of predicting the existence of tropospheric radio waveguides by using data on the current conditions of radio wave propagation over the sea based on the signals of the automatic ship identification system AIS. Conclusions. Proposals have been developed to improve the accuracy of measuring the range and radial velocity of SO and AO at waveguide propagation of radio waves over the sea surface. A promising area for further research may be to identify ways to optimise the measurement of angular coordinates in modern RS during waveguide propagation of radio waves over the sea surface.

A Millimeter-Wave Broadband Multi-Mode Substrate-Integrated Gap Waveguide Traveling-Wave Antenna with Orbit Angular Momentum.

Orbit angular momentum (OAM) has been considered a new dimension for improving channel capacity in recent years. In this paper, a millimeter-wave broadband multi-mode waveguide traveling-wave antenna with OAM is proposed by innovatively utilizing the transmitted electromagnetic waves (EMWs) characteristic of substrate-integrated gap waveguides (SIGWs) to introduce phase delay, resulting in coupling to the radiate units with a phase jump. Nine "L"-shaped slot radiate elements are cut in a circular order at a certain angle on the SIGW to generate spin angular momentum (SAM) and OAM. To generate more OAM modes and match the antenna, four "Π"-shaped slot radiate units with a 90° relationship to each other are designed in this circular array. The simulation results show that the antenna operates at 28 GHz, with a -10 dB fractional bandwidth (FBW) = 35.7%, ranging from 25.50 to 35.85 GHz and a VSWR ≤ 1.5 dB from 28.60 to 32.0 GHz and 28.60 to 32.0 GHz. The antenna radiates a linear polarization (LP) mode with a gain of 9.3 dBi at 34.0~37.2 GHz, a l = 2 SAM-OAM (i.e., circular polarization OAM (CP-OAM)) mode with 8.04 dBi at 25.90~28.08 GHz, a l = 1 and l = 2 hybrid OAM mode with 5.7 dBi at 28.08~29.67 GHz, a SAM (i.e., left/right hand circular polarization (L/RHCP) mode with 4.6 dBi at 29.67~30.41 GHz, and a LP mode at 30.41~35.85 GHz. In addition, the waveguide transmits energy with a bandwidth ranging from 26.10 to 38.46 GHz. Within the in-band, only a quasi-TEM mode is transmitted with an energy transmission loss |S21| ≤ 2 dB.

Water jet guided high-power laser energy transmission loss analysis

Water jet guided high-power laser energy transmission loss analysis

Sustainable Material Selection in New Constructions: A Brute‐Force Optimization Framework Using Parallel Computing, Cost Benefits, and Thermal Performance Analysis

Sustainable construction practices rely on carefully selecting building materials and balancing environmental and economic considerations. This study examines the complex link between local climate, market dynamics, and building material selection. Market data analysis, parametric modeling, and brute‐force optimization are used to provide insights into construction decision‐making. Across 5540 simulations, a thorough assessment of the financial and energy performance of various materials for walls, roofs, windows, and floors is conducted. Incorporating Pareto ranking, parallel simulation, and sensitivity analysis, the comprehensive evaluation reveals the intricate tradeoffs between cost, thermal properties, and energy savings. The findings highlight the potential for optimal external wall solutions to reduce U‐values by up to 30% and achieve source energy savings of up to 25% source energy savings across diverse climates. By emphasizing the importance of local context in material selection, this study highlights how energy consumption patterns and transmission losses influence financial and energy performance, thus advancing sustainable construction practices.

Mode-matching technique for analyzing scattering in elastic shell chambers: Applications in trifurcated waveguide systems

This study presents a comprehensive investigation into the behavior of elastic shell chambers used for noise control and vibration mitigation in engineering applications. The study focuses on the analysis of fluid–structure coupled waves in a cylindrical waveguide system with trifurcated structures and membrane discs. The mode-matching technique is employed to analyze the scattering characteristics of the elastic chamber shell. Numerical simulations and analytical techniques are used to explore the interplay between material properties, geometric configurations, and loading conditions. The Galerkin formulation is utilized to model the response of membrane bridging discs and elastic shell regions. Linear algebraic systems are solved numerically to obtain the scattering amplitudes, and the convergence of the obtained solution is assessed. The energy conservation law and transmission loss are analyzed to evaluate the accuracy and convergence behavior of the system. The numerical results provide insights into the scattering behavior of the structure, showing the influence of frequency, chamber radius, and edge conditions. The findings highlight the importance of parameter selection and boundary conditions in guiding structures and provide a basis for design optimization.

Joint scheduling and offloading of computational tasks with time dependency under edge computing networks

Mobile edge computing is an emerging technology paradigm that improves mobile devices’ computational power and efficiency by offloading computational tasks to edge servers. However, there are still some problems: (1) Ignoring the complex time dependencies of compute-intensive or latency-sensitive tasks, leading to the omission of offload scheduling opportunities for fine-grained sub-tasks within a task, thus reducing the computational power of the mobile device and the utilization of edge resources; (2) Overly biased towards optimizing task execution latency and ignoring the balance between data transmission latency and energy loss, reducing the scheme versatility in natural computing environments. Aiming at the above problems, this paper models the complex dependencies, transmission time, and execution time between computing tasks, constructs a mathematical model of the scheduling and offloading process of computing tasks, and a joint task scheduling and offloading method (N-JSU) based on Nash equilibrium is designed. This offloading strategy is divided into two steps: first, the average latency of each task is analyzed, and the scheduling order of the computational tasks is determined based on the highest response ratio of the tasks; secondly, the optimal solution is determined by iterative search to offload the most suitable IoT tasks or computing tasks to the edge server. The experimental results show that this offloading strategy can effectively reduce the latency of computationally intensive edge network tasks and improve the resource utilization of the edge server.

Topological Design of Two-Dimensional Phononic Crystals Based on Genetic Algorithm.

Phononic crystals are a kind of artificial acoustic metamaterial whose mass density and elastic modulus are periodically arranged. The precise and efficient design of phononic crystals with specific bandgap characteristics has attracted increasing attention in past decades. In this paper, an improved adaptive genetic algorithm is proposed for the reverse customization of two-dimensional phononic crystals designed to maximize the relative bandwidth at low frequencies. The energy band dispersion relation and transmission loss of the optimal structure are calculated by the finite-element method, and the effective wave-attenuation effect in the bandgap range is verified. This provides a solution for the custom-made design of acoustic metamaterials with excellent low-frequency bandgap sound insulation or other engineering applications.

Analysis of Asymmetric Fault Commutation Failure in HVDC System Considering Instantaneous Variation of DC Current

HVDC is an important part of reducing energy transmission losses and maintaining energy sustainability. Commutation failure is the most common fault in HVDC systems, but existing commutation failure analysis approaches for HVDC systems do not consider the effects of instantly increasing direct current on the turn-off angle after an asymmetric fault in the AC system. To address this problem, we developed a commutation failure analysis approach that considers instantaneous variation of the DC current and AC voltage after asymmetrical faults. Firstly, the effects of the AC voltage and the DC current on the turn-off angle and the coupling relationship between the two are analyzed. Secondly, an equivalent mathematical model of the DC line, which covers the reactance, is built in Laplace space. Combined with the phase angle offset generated by the voltage after an asymmetric fault, a single relation expression containing only the AC voltage and turn-off angle is obtained by decoupling the DC current and AC voltage. The critical instantaneous AC voltage leading to system commutation failure is then derived based on the critical turn-off angle. Lastly, based on the CIGRE HVDC model built in the PSCAD electromagnetic transient simulation software (PSCAD v46), the accuracy of the proposed commutation failure analysis method compared with the other two methods is verified via simulation experiments under different grounding impedance values, and the applicability of the proposed method is further verified using simulation experiments with different smoothing reactor parameters.

The Improved DC Breakdown Strength Induced by Enhanced Interaction between SiO2 Nanoparticles and LLDPE Matrix.

Direct current (DC) power transmission systems have received great attention because it can easily integrate many types of renewable energies and have low energy loss in long-distance and large-capacity power transmission for electricity global sharing. Nanoparticles (NPs) have a positive effect on the insulation properties of polymers, but weak interaction between NPs and polymer matrix greatly decreases the effort of NPs on the enhancement of insulation properties, and thereby limits its engineering application. In this work, grafting strategy was used to link the modified NPs and polymer matrix to improve their interactions. Silica NPs (SiO2-NPs) were modified by 3-(methacrylyloxy) propyl-trimethoxysilane (MPS) to introduce highly active groups on the SiO2-NPs surface, followed by the pre-irradiated linear low-density polyethylene (LLDPE) being easily grafted onto the MPS modified SiO2-NPs (MPS-SiO2-NPs) in the melt blending process to obtain LLDPE-g-MPS-SiO2-NPs nanocomposites. Fourier-transform infrared (FT-IR) spectrum and X-ray photoelectron spectroscopy (XPS) confirm the successful incorporation of MPS into SiO2-NPs. Transmission electron microscopy (TEM) verifies that the modified SiO2-NPs exhibits more uniform distribution. The rheology result shows that the interaction between MPS-SiO2-NPs and LLDPE significantly improves. More importantly, the LLDPE-g-MPS-SiO2-NPs nanocomposites displays superior DC breakdown strength to that fabricated by conventional modification methods. When the addition of MPS-SiO2-NPs is 0.1 wt%, the highest DC breakdown strength values of 525 kV/mm and 372 kV/mm are obtained at 30 °C and 70 °C, respectively, and high DC breakdown strength can be well maintained in a wide loading range of NPs.

Capacity optimal configuration and collaborative planning of multi-region integrated energy system

At present, the integrated energy system (IES) is designed and built separately according to the peak load of respective regions, without considering the combination of multi-regional energy, which will lead to low energy efficiency of equipment and decline of economic benefits. In this paper, considering heating networks, a multi-region IES collaborative planning model is proposed. For the ring-shaped heating network between the various regional CCHP systems, a heating network model is established considering the node flow balance, thermal energy-flow constraint and thermal loss balance constraint. Combining the energy balance constraint of the CCHP system and the heating network model, a mixed integer linear programming (MILP) model of the capacity of the multi-region CCHP system for the collaborative optimization is established. Finally, a comprehensive area in China Xiongan New Area is taken as an example for simulation analysis. In view of the four types of users, including business area, office area, residential area, industrial area, the two scenarios are deeply compared and analyzed. The saving rate of scenario 2 compared with scenario 1 is about 8.95%. The multi-region collaborative planning and optimize operation in this paper can greatly improve gas turbine utilization, reduce gas boiler configuration capacity, minimize thermal energy transmission loss, and significantly reduce operating costs.

Energy redistribution assisted charging of WRSNS with multiple mobile chargers having multiple base stations

The utilization of mobile chargers (MCs) for charging the nodes in wireless rechargeable sensor networks (WRSNs) has been a significant research subject. However, existing works mainly focused on planning the moving paths of MCs whereas neglecting opportunities to enhance charging efficiency through the exploitation of energy redistribution (ERD) processes among nodes and the broadcast nature of radio signals. To improve charging efficiency by exploiting these opportunities, we investigate the underlying energy redistribution assisted charge scheduling (ERACS) problem. This problem aims to identify a charging schedule that meets the nodes’ energy demands while minimizing energy loss and time span in WRSNs with multiple MCs and multiple base stations. After demonstrating the NP-hardness of the ERACS problem, we propose an energy loss minimization charge scheduling (ELMCS) algorithm to solve the problem. The ELMCS algorithm first constructs and solves a linear programming problem to obtain a time-length list that leads to minimum transmission energy loss. It then constructs the moving path set of MCs using a heuristic MCs moving path planning strategy that we propose in this paper to minimize moving energy loss. Additionally, after generating an MC energy transmission list that describes the MCs’ energy transmission time intervals, the ELMCS algorithm minimizes the time span by capitalizing on concurrent energy transmission opportunities while ensuring optimal energy loss. Finally, we compare our ELMCS algorithm with typical algorithms, and the simulation results demonstrate that our algorithm is markedly superior.

Low Frequency Attenuation Characteristics of Two-Dimensional Hollow Scatterer Locally Resonant Phonon Crystals.

The finite element method (FEM) was applied to study the low frequency band gap characteristics of a designed phonon crystal plate formed by embedding a hollow lead cylinder coated with silicone rubber into four epoxy resin short connecting plates. The energy band structure, transmission loss and displacement field were analyzed. Compared to the band gap characteristics of three traditional phonon crystal plates, namely, the square connecting plate adhesive structure, embedded structure and fine short connecting plate adhesive structure, the phonon crystal plate of the short connecting plate structure with a wrapping layer was more likely to generate low frequency broadband. The vibration mode of the displacement vector field was observed, and the mechanism of band gap formation was explained based on the spring mass model. By discussing the effects of the width of the connecting plate, the inner and outer radii and height of the scatterer on the first complete band gap, it indicated that the narrower the width of the connecting plate, the smaller the thickness; the smaller the inner radius of the scatterer, the larger the outer radius; and the higher the height, the more conducive it is to the expansion of the band gap.

Joint Energy Loss and Time Span Minimization for Energy-Redistribution-Assisted Charging of WRSNs With a Mobile Charger

The use of mobile chargers (MCs) to charge the nodes in wireless rechargeable sensor networks via wireless power transfer (WPT) has attracted much research effort. Existing works mostly concentrate on path planning whereas neglecting the opportunities to improve charging coverage and efficiency by exploiting the energy redistribution (ERD) process among nodes and an MC’s capability of charging multiple nodes simultaneously via WPT. To exploit such opportunities, we study the underlying ERD-assisted MC charge scheduling (ERAMCCS) problem, i.e., to find a charging schedule satisfying the nodes’ energy demands with minimum energy loss and minimum time span. After proving that the problem is NP-hard, we propose a charge scheduling algorithm based on the greedy idea (CSBGI), which provides a solution by decoupling the problem into two subproblems: 1) ERAMCCS-Energy and 2) ERAMCCS-Time, to minimize the energy loss and the time span, respectively. By partitioning the energy loss into transmission energy loss and moving energy loss, we solve the ERAMCCS-Energy problem by minimizing the two parts, respectively, by formulating and solving some linear programming problems and traveling salesman problem problems based on the charging position set. The charging position set is iteratively refined by identifying and removing redundant charging positions. For the ERAMCCS-Time problem, concurrent energy transmission opportunities are exploited to try to minimize the time span of the schedule. We demonstrate some key properties of CSBGI, such as its approximation ratio in terms of energy loss and its time complexity. Testbed experiments and numerical simulations confirm the superiority of CSBGI over typical algorithms.

Event-triggered integral sliding mode control for uncertain networked linear control systems with quantization.

In this paper, the integral sliding mode (ISM, SM) controller is designed to address the problem of implementing non-periodic sampled data for a class of networked linear systems with matched and unmatched uncertainties. Due to the redesigned gain of the nominal controller, the feedback control used by the nominal controller guarantees the asymptotic stability of the uncertain networked linear system. The discontinuous control uses intermittent control based on the reaching law to achieve the finite-time reachability of practical SM band. Based on the defined measurement error, the event-triggered (ET) condition can be derived, and furthermore, it guarantees a sufficient condition for the existence of the actual SM. On this basis, a quantization scheme is added to further decrease the network transmission burden of the linear system. No Zeno behavior occurs in the system owing to the existence of a positive lower bound of inter-event time. Compared with the conventional integral sliding mode control (ISMC, SMC), the proposed control law can not only relieve the network burden, but also decrease the transmission energy loss. Finally, simulation results of a numerical example and a mass-spring damping system demonstrate the effectiveness of the proposed method.

Analysis of optical transmission energy loss for Micro Optical-Electro Mechanical fuze Safety and Arming System

Analysis of optical transmission energy loss for Micro Optical-Electro Mechanical fuze Safety and Arming System