Instantaneous Energy Research Articles

Co-combustion performances of biomass pyrolysis semi-coke and rapeseed cake: PCA, 2D-COS and full range prediction of M-DAEM via machine learning

Biomass pyrolysis semi-coke (PC) is a refractory byproduct of biomass refinery system, and its efficient downstream disposal is of significance to improve the bioenergy utilization efficiency. Herein, we proposed an environmentally friendly co-combustion strategy to explore the synergistic conversion of PC with agricultural waste rapeseed cake (RC). The co-combustion interaction, kinetics, prediction and emission responses were determined through principal component analysis (PCA), multiple distributed activation energy model (M-DAEM), artificial neural network (ANN) and two-dimensional correlation spectroscopy (2D-COS) analysis. The results indicated that the P/R (mixed) ratio in 1:1 strengthened the reaction rate for main incineration stage, whereas lower P/R ratio advanced the peak temperature and cooperated with temperature range in 730–790 K to facilitate co-combustion synergies. The prediction of the kinetic distribution under all mixed ratios was successfully conducted (R2 = 0.999863) through M-DAEM coupling with ANN, from which the activation energy distribution centers E0 and standard deviation σ were in the ranges of 115.23–270.84 kJ/mol and 2.89–42.11 kJ/mol, respectively. Co-combustion resulted in centralized activation energy distribution, and successfully lowered the reaction energy barriers while augmenting the instantaneous energy release. Meanwhile, the temperature dependency responses of flue gas were varied significantly as a function of mixed ratios and temperatures.

Nanoarchitectonics of MXene Derived TiO2 /Graphene with Vertical Alignment for Achieving the Enhanced Supercapacitor Performance.

Structural engineering and hybridization of heterogeneous 2D materials can be effective for advanced supercapacitor. Furthermore, architectural design of electrodes particularly with vertical construction of structurally anisotropic graphene nanosheets, can significantly enhance the electrochemical performance. Herein, MXene-derived TiO2 nanocomposites hybridized with vertical graphene is synthesized via CO2 laser irradiation on MXene/graphene oxide nanocomposite film. Instantaneous photon energy by laser irradiation enables the formation of vertical graphene structures on nanocomposite films, presenting the controlled anisotropy in free-standing film. This vertical structure enables improved supercapacitor performance by forming an open structure, increasing the electrolyte-electrode interface, and creating efficient electron transport path. In addition, the effective oxidation of MXene nanosheets by instantaneous photon energy leads to the formation of rutile TiO2 . TiO2 nanoparticles directly generated on graphene enables the effective current path, which compensates for the low conductivity of TiO2 and enables the functioning of an effective supercapacitor by utilizing its pseudocapacitive properties. The resulting film exhibits excellent specific areal capacitance of 662.9 mF cm-2 at a current density of 5mA cm-2 . The film also shows superb cyclic stability during 40000 repeating cycles, maintaining high capacitance. Also, the pseudocapacitive redox reaction kinetics is evaluated, showing fast redox kinetics with potential for high-performance supercapacitor applications.

Performance of hydrocarbon refrigerants in a refrigerator with liquid line magnet and CNT nano-lubricant

The issues of flammability associated with A3-class hydrocarbon-based refrigerants are controllable by limiting their mass charges. However, these reductions in their mass charge below certain limits deteriorate their performance efficiency. In this experimental study, we analyzed the effects of a liquid line magnetic field (Mag), multi-wall carbon nanotube (CNT) nano-lubricant, and the combination of both (Mag-Nano) on the performance of a very low mass charge (i.e., 30 g) of R600a and LPG refrigerants, as a replacement to the 100 g R134a refrigerant in a domestic refrigeration system. The refrigerants were tested with and without CNT nano-lubricant (pure), two pairs of 3000 Gs liquid line mounted O ring N50 permanent magnets (Mag), 0.2 g/L concentration of CNT nano-lubricant (Nano), and in combination with a liquid line magnetic field and CNT nano-lubricant (Mag-Nano). The performance evaluation of the refrigerants includes the determination of coefficient of performance (COP), evaporator air temperature, volumetric refrigeration capacity, instantaneous power consumption, cumulative energy consumption, and energy cost. A reduction in the COP of R600a and LPG was observed to be about 11–42% and 14–26%, respectively, when compared to R134a. The R134a refrigerant had the lowest evaporator air temperature of −24.5 °C and the highest instantaneous power consumption of 74.6 W. The R600a-Mag-Nano refrigerant is the most efficient option, having the lowest instantaneous power consumption, energy cost, and cumulative energy consumption. The adoption of hydrocarbon refrigerants is more cost-effective than using the R134a refrigerant, resulting in a cost saving of about 8–26%. In conclusion, the proposed methods adopted to enhance the performance of refrigeration system, are very safe and effective.

Multi-Feature Fusion-Based Instantaneous Energy Consumption Estimation for Electric Buses

Multi-Feature Fusion-Based Instantaneous Energy Consumption Estimation for Electric Buses

Stationary state of harmonic chains driven by boundary resetting

We study the nonequilibrium steady state of an ordered harmonic chain of N oscillators connected to two walls which undergo diffusive motion with stochastic resetting. The intermittent resetting of the walls effectively emulates two nonequilibrium reservoirs that exert temporally correlated forces on the boundary oscillators. These reservoirs are characterized by the diffusion constants and resetting rates of the walls. We find that, for any finite N, the velocity distribution of the bulk oscillators remains non-Gaussian, as evidenced by a non-zero bulk kurtosis that decays . We calculate the spatio-temporal correlation of the velocity of the oscillators both analytically as well as using numerical simulation. The signature of the boundary resetting is present at the bulk in terms of the two-time velocity correlation of a single oscillator and the equal-time spatial velocity correlation. For the resetting driven chain, the two-time velocity correlation decay as at the large time, and there exists a non-zero equal-time spatial velocity correlation when . A non-zero average energy current will flow through the system when the boundary walls reset to their initial positions at different rates. This average energy current can be computed exactly in the thermodynamic limit. Numerically we show that the distribution of the instantaneous energy current at the boundary is independent of the system size. However, the distribution of the instantaneous energy current in the bulk approaches a stationary distribution in the thermodynamic limit.

Locating Sources of Sub-Synchronous Oscillations in Wind Farms Based on Instantaneous Energy Supply on Port and Bicoherence

The sub-synchronous oscillation (SSO) which occurred in direct-driven wind generators (DDWG) based wind farms became a research hotspot. The SSO excited the shaft torsional vibration of thermal generators and caused trip failures, leading to economic losses and stabilization problems. However, the existing phasor-based oscillation source locating methods cannot be applied to the SSO since the power system quasi-steady-state assumption was not satisfied in the SSO scenarios. Thus, a novel locating method for SSO sources was urgently required. To fill this gap, this paper proposed an improved method for locating nonlinear sub-synchronous oscillation sources based on Energy Supply on Port (ESP) and bicoherence. The ESP was calculated with the instantaneous values of measured voltages and currents at some predefined network interfaces, i.e., the ports. The tendency of the ESP indicated the transient energy injection from a certain subsystem into the rest of the network during a designated period, which can help figure out the oscillation source of the SSO. After oscillation source localization, the nonlinear index and its threshold were proposed by defining the bicoherence coefficient in consideration of the nonlinear oscillation characteristics. According to the power-quality standard and the comparison of the bicoherence with the threshold, the nonlinearity of the oscillation source was examined. The feasibility and effectiveness of the proposed method were proved in the case study which simulated the oscillation scene of the accident in Hami.

Extraction and identification of spectrum characteristics of coal and rock hydraulic fracturing and uniaxial compression signals

Microseismic (MS) events generated during coal and rock hydraulic fracturing (HF) include wet events caused by fracturing fluid injection, in addition to dry events caused by stress perturbations. The mixture of these two events makes effective fracturing MS events pickup difficult. This study is based on physical experiments of different coal and rock HF and uniaxial compression. The differences of waveform characteristic parameters of various coal and rock ruptures were analyzed using the Hilbert–Huang transform, leading to some useful conclusions. The phase characteristics of the acoustic emission (AE) energy differed significantly and responded well to the pumping pressure curve. The AE waveforms of HF exhibit similar energy and frequency distribution characteristics after Empirical mode decomposition. The main frequency bands for coal, sandstone, and shale samples are 100–300 kHz, while the mudstone sample is in the range of 50–150 kHz. The decay ratios for coal, sandstone, shale and mudstone samples are 0.78, 0.83, 0.67 and 0.85, respectively. When compared to the uniaxial compression test, the main frequency bands of HF were reduced for coal, sandstone and mudstone samples, whereas shale remained essentially unchanged. The duration, instantaneous energy, and total energy of the HF waveform are smaller than those of uniaxial compression, while the decay ratio is greater, especially for the mudstone samples. The waveform characteristic parameters, trained using the multilayer perceptron neural network, can effectively identify HF and uniaxial compression events with an accuracy of 96%.

Design and Development of Optimal and Deep-Learning-Based Demand Response Technologies for Residential Hybrid Renewable Energy Management System

The principal goal of this study is to conduct a techno-economic analysis of hybrid energy generation designs for residential-form houses in urban areas. Various possibilities for a form house electrification system are created and simulated in order to determine an optimum ideal configuration for meeting residential load demand with an increase in energy capacity and minimal investment. Using NREL’s HOMER optimization tool, a case-study-based virtual HRE model is developed. Pre-assessment data and relevant operation constraints are used to build the system’s objective functions. The instantaneous energy balance algorithm technique is used to solve the multi-objective function. The overall optimization procedure is sandwiched between two supporting advanced approaches, pre- and post-operations. The development of an optimal techno-economic hybrid energy generation system for the smooth fulfillment of urban load demand is aided by novel deep belief network (NDBN)-based pre-stage load demand predictions and an analysis of the necessary demand side management (DSM)practicing code for utility efficiency improvements in post-stage simulations.

Vibration Reduction and Explosion Control Investigation for an Ultra-Shallow Buried Tunnel under Crossing Buildings Based on HHT Analysis.

With the rapid development of underground space utilization, the excavation of new tunnels with ultra-shallow under crossing buildings using the drilling and blasting method is gradually increasing. The blasting vibration will undoubtedly affect the surrounding buildings. Reducing the impact of blasting vibration on ground buildings has become an important technical challenge faced by tunnel blasting technicians. The inlet end of the Xi'an-Chengdu High-Speed Railway Xiannvyan Tunnel passes below a village through an ultra-shallow buried section; as a result, blasting vibration control is a major concern. A design scheme for a 0.6 m footage in tunnel was proposed and verified through field tests. A 0.8 m footage scheme and 1.8 m footage millisecond interference vibration reduction scheme were proposed, respectively. Based on the HHT analysis, by comparing the surface vibration velocities and instantaneous energy obtained from the millisecond delay detonation of cutting holes and the detonation of different charging schemes, we found that the free surface, mass of single dynamite charges, and tunnel burial depth had significant influences on the surface vibration.

A problem-specific knowledge based artificial bee colony algorithm for scheduling distributed permutation flowshop problems with peak power consumption

A distributed permutation flowshop scheduling problem (DPFSP) with peak power consumption is addressed in this work. The instantaneous energy consumption of each factory cannot exceed a threshold. First, a mathematical model is developed to describe the concerned problem. Second, an improved artificial bee colony (IABC) algorithm is proposed. Based on problem-specific knowledge, three new solution generation operators, e.g., shift, swap, and speed adjust, are designed for employ bees and onlooker bees. A local search operation is developed to improve the quality of current best-known solution in each iteration. 450 instances are solved to evaluate the performance of IABC via comparing to seven state-of-the-art algorithms. The average relative percentage increase (ARPI) of IABC ranks 1 among all compared algorithms. The results and discussions show that the proposed IABC algorithm has strong competitiveness for solving the DPFSP with peak power consumption.

Damage localization in carbon fiber composite plate combining ultrasonic guided wave instantaneous energy characteristics and probabilistic imaging method

The ultrasonic guided wave (UGW) imaging technique has become a promising tool in composite structure health monitoring. However, most algorithms extract damage characteristics with time or frequency domain method. These methods cannot characterize the nonlinear and nonstationary damage signals. Based on the Hilbert–Huang transform, the phenomenon of instantaneous energy increase and decrease is studied, and the rule of energy change and distance from damage to sensor path is summarized. The damage index based on instantaneous energy characteristics is proposed. A probabilistic imaging method is proposed, which introduces a probability distribution function based on the elliptical method for fusion imaging with traditional probability distribution function. The experiment of 74 points on carbon fiber composite plate was performed. The average localization error was 3.56 mm and the maximum was 9.68 mm. The proposed method has high localization accuracy and stability and has application prospects in high-end equipment composite structure health monitoring.

Optimal design method and benefits research for a regional integrated energy system

Regional integrated energy systems (RIES) have garnered increased attention because they highly utilize renewable energy, comprehensive efficiency, and flexible operation. However, the current research on RIESs is mainly based on burning natural gas and supplemented by renewable energy, which will consumes much primary energy and generates corresponding carbon emissions. Therefore, a RIES contained various renewable energy sources and station energy sharing was constructed in this paper. Both the collaborative optimization model, which considered the operating parameters and system configuration, and the hierarchical optimization model, which optimizes the equipment configuration at the upper layer and the operational parameters at the underlayer, were constructed, respectively. Taking a multi-function low-carbon park as an example, the isolated integrated energy system (IIES) and RIES performances were explored. Finally, the operation cost, carbon emission, and interactive power in the separated production system, IIES and RIES were analyzed and discussed from a long-short time scale perspective. The results showed that the carbon emission, interactive power, and energy supply cost of the RIES's unit area are 7.62 kg/m2, 10.07 kWh/m2, and 40.55 CNY/m2, respectively. Long time scale perspective (Years or months), RIESs could significantly reduce carbon emissions and interactive power. However, on a short time scale viewpoint (Hours), the system's instantaneous energy conservation and carbon reduction effect was general; meanwhile, the maximum grid-connected power in IIES and RIES was 2617.7 and 2712.0 kW, respectively.

Transfer mechanism and criteria for static–dynamic failure of granite under true triaxial unloading test

In the construction procedure of infrastructure, the excavation disturbance significantly changes the initial stress state of rocks in deep geotechnical engineering, and a rock burst would occur accompanied by the ejection of rock block. In the present study, a true triaxial unloading test and its corresponding numerical analysis based on the three-dimensional particle flow code (PFC3D) are conducted on granite specimens to acquire characteristic information of static and dynamic failure during unloading and to explore the criteria for determining static and dynamic failure. The results indicate that the failure modes of granite under true triaxial unloading can be classified into three categories: ① no obvious coalesced crack, ② a main coalescence shear crack, and ③ a main coalescence shear crack with a V-shaped pit. The instantaneous kinetic energy in static failure is characterized by a sharp increase and sporadic sharp increases, while that in dynamic failure shows a sharp increase, a short quiet period, and a substantial increase. The critical stress combination for the transformation of static–dynamic failure of granite is proposed, which is consistent with the experimental results. The number of shear cracks gradually increases in static failure, while it suddenly increases in dynamic failure. During the transformation from static failure to dynamic failure, the ratio of a tensile crack number to that of shear crack number decreases. The proportion of shear cracks in particle bonding increases, while the trend of tensile failure weakens. However, tensile failure remains predominant in granite, accompanied by shear failure.

Accuracy analysis using the EMD and VMD for two-terminal transmission line fault location based on traveling wave theory

This paper presents an accuracy analysis from the application of techniques for the extraction of characteristic data from current and voltage signals in transmission line fault location based on traveling wave theory. The techniques used were the empirical mode decomposition and the variational mode decomposition associated with Teager energy operator, which helps to identify the instantaneous energy of the first intrinsic mode function. The simulation of the power system was carried out using the MATLAB/Simulink® software, for a test system consisting of a 200 km long transmission line between two Thevenin equivalents. Data is obtained from both terminals. The fault resistance was fixed at 100 Ω, but the incidence angle, the sampling rate and the fault location were varied for all fault types. The numerical and graphical results proved that the techniques can extract the characteristic data of the current and voltage signals and estimate the fault distance to the terminal with high accuracy, depending only on the sampling rate adopted.

Fault protection scheme of flexible DC grid based on transient power instantaneous energy difference

The DC line protection is the key to the stable operation of the multi-terminal flexible DC grid, and the current limiting reactor (CLR) as the boundary condition provides great convenience for the design of the flexible DC grid fault protection scheme. Using the boundary condition characteristics of the CLR, the paper proposes a fault protection method for flexible DC grid based on transient power instantaneous energy (IE) difference. First, the equivalent circuit of the DC line of the flexible DC grid under different faults is established. On this basis, the conclusion that the transient power amplitude of internal fault is much larger than the external is deduced from the full-power in the time-domain. The Teager energy operator is used to calculate the maximum IE of the transient power, and then the internal and external faults are identified. Secondly, according to the difference of the transient power amplitude of the CLR on the fault pole and the healthy pole, the ratio of the IE of the positive and negative CLR transient power is used to construct the fault pole selection. The scheme is simple and easy to implement, and does not need to consider the synchronization problem of data at both sides. Finally, the simulation results show that the proposed method can better satisfy the speediness and selectivity requirements of DC grid protection. The scheme can accurately detect faults under different working conditions, and has strong fault resistances capability.

An Improved Search Algorithm for WSN with Charging Nodes

The existing semi-centralized stochastic election approach, Stochastic Election of Appropriate Range Cluster Heads (SEARCH) is analyzed and features are improved which, boasts low time cost, improved stable period, and eliminates the unfavorable scenario, that no cluster head emerges during some specific rounds. However, the implementation of SEARCH in WSNs with solar charging nodes offers very marginal improvement in a stable period. This proves the inefficiency of the algorithm in handling these charging nodes. The improvement offered aims to make the algorithm, more energy aware and hence comparatively well organized in handling the charging nodes in the network. This improvement, equipped with dynamic tracking of instantaneous node energy shows a promising way to extend clustering algorithms to networks with chargeable nodes. In addition, the existing SEARCH algorithm’s cluster head election procedure lacks a futuristic view of the minimum energy requirement for successful operation throughout an entire round. Intermediate cluster head death can be detrimental, to network performance by paralyzing the corresponding clusters, resulting in total data transmission failure of all nodes in that cluster. Implementing the improved SEARCH algorithm drastically reduces the bit loss by 95%, with increasing the transmitted bits successfully by 4%. The overall lifetime of the WSN improves by around 30% and the number of cluster heads dying prematurely in the middle of round operation is reduced by 89%. This paper analyzes and refines a current clustering algorithm, thereby promisingly enhancing its capacity to boost the overall network performance.

Modulation depth of the gyrosynchrotron emission as an identifier of fundamental sausage modes

Aims. We aim to study the intensity, the modulation depth, and the mean modulation depth of the gyrosynchrotron (GS) radiation as a function of the frequency and the line of sight (LOS) in fast sausage modes. Methods. By solving the 2.5D magnetohydrodynamics (MHD) ideal equations of a straight coronal loop considering the chromosphere and with typical flaring plasma parameters we analyse the wavelet transform of the density and the GS emission for different radio frequencies and different spatial resolutions, given impulsive and general perturbations with energies in the microflare range. Results. A wavelet analysis performed over the GS radiation emission showed that a fast fundamental sausage mode of ∼7 s with a first harmonic mode of 3 s developed, for all the initial energy perturbations used. For both the high spatial resolution (central pixel integration) and the low spatial resolution (entire loop integration), the larger the radio frequency, the larger the modulation depth. However, high- and low-resolution integrations differ in that the larger the LOS angle with respect to the loop axis, the larger and smaller the modulation depth, respectively. Conclusions. Fast MHD modes triggered by instantaneous energy depositions of the order of a microflare energy are able to reproduce deep intensity modulation depths in radio emission as observed in solar events. As the trends of the GS emission previously obtained for a linear and forced oscillation remain present when analysing a more general context, considering the chromosphere and where the sausage mode is triggered by an impulsive, non-linear perturbation, it seems that the behaviour found can be used as observational identifiers of the presence of sausage modes with respect to other quasi-periodic pulsation features. It can be inferred from this that finite-amplitude sausage modes have the potential to generate the observed deep modulation depths.

Accelerated Editing Method for Vehicle Durability Fatigue Load Spectrum Based on Wigner-Ville Transform.

A Wigner-Ville transform-based (WVT-based) load spectrum fast editing method for vehicle parts is proposed to improve the efficiency of durability tests. In this method, the instantaneous energy spectrum (IES) of the original time-domain signal is obtained via the Wigner-Ville transform, which is used as a criterion to identify time-domain points of ineffective damage contribution. A genetic algorithm (GA) based threshold optimization model is also proposed to automatically set the threshold of the IES under consideration of the relative damage requirements and statistical parameters of the signal. The effectiveness of the above proposed editing method is demonstrated by compiling an SUV's suspension coil spring signal obtained from physical sensor-based measurements. Meanwhile, the same spectrum is also processed using time-domain editing, Short-time Fourier-transform, and S-transform methods for comparison. The results show that the WVT-based edited spectrum has a time-duration retention ratio of about 76.30%, which is significantly superior to other methods, with the same pseudo-damage retention and statistical parameter error constraints. Moreover, in combination with the fatigue simulation analysis, it verifies that the load effect of the edited spectrum matches well with that of the original. Thus, the proposed method is considered more effective for compiling component load signals in vehicle acceleration durability tests.

Mechanical Response Characteristics and Law of Instantaneous Energy Conversion for Water-Bearing Coal–Rock Masses Subjected to Mining-Induced Stress

Mechanical Response Characteristics and Law of Instantaneous Energy Conversion for Water-Bearing Coal–Rock Masses Subjected to Mining-Induced Stress

Heat and mass transfer in electron beam additive manufacturing

The electron beam wire-feed additive manufacturing (EBAM) technology utilizes a high-energy electron beam as a heat source to bombard a metal wire in the vacuum environment to form a molten pool. The stability and quality of the deposition mainly depend on the transition behavior of the droplet. To conduct this research, a high-fidelity thermo-fluid dynamic simulation model based on the local reconstruction of the 3D model was developed and verified. The model used the Monte-Carlo algorithm to update the scattering trajectories and residual energies of high-energy electrons on the irradiated surface of the wire and molten pool at each time step in the numerical calculation. Quantitatively analyzed the “electron-wire” instantaneous energy coupling mechanism in the droplet transition mode, insertion transition mode, and liquid bridge transition mode, and finally established an energy-matching criterion for maintaining a stable deposited track morphology. The results show that during the initial stage of wire melting, the droplet will climb along the wire feeding direction, grow under gravity, and eventually drop under the combined effects of gravity and recoil pressure. Different forms of molten droplets will form various solidification morphology, with the liquid bridge transition mode being the most desirable. To maintain a stable liquid bridge transition, it is necessary to control the droplet generation height within the range of 0–2.7 mm. The collapse of the deposited track, caused by heat accumulation during the multilayer deposition, would also alter the droplet generation height. Therefore, to maintain the liquid bridge transition mode in the multilayer multi-channel forming process, it is also necessary to ensure that the energy density of the deposited track is slightly greater than 1.16×1010 J/m3 and the energy density of the wire is slightly greater than 2.63×1010 J/m3.