Auxiliary Ground Research Articles

Cathodic Protection Potential Distribution and Anode Ground Bed Optimization Scheme for Low-pressure City Gas Pipe

ABSTRACT The low-pressure gas pipes in some old residence communities of China are often electrically connected to each other and groundings, which brings about great challenges to the design of cathodic protection (CP) system due to large CP current consumption and attenuation effects. The field tests on potential distribution of three types of anode ground beds were conducted, including deep well auxiliary anode ground bed, shallow auxiliary anode ground bed far from gas pipes, and shallow auxiliary anode ground bed close to gas pipes. The results showed that, the shallow auxiliary anode ground bed close to gas pipe provided more protection with less current than other two types of ground bed. Numerical simulations on CP potential distribution of different anode ground beds were conducted and the boundary conditions were determined by inversion calculation based on field tests. Based on the field test and numerical simulation results, the anode ground bed suitable for CP of low-pressure gas pipes electrically connected to groundings is the shallow auxiliary anode ground bed close to gas pipes and the optimized distribution scheme for shallow anode ground beds were proposed.

Optimization of Ground Source Heat Pump System Based on TRNSYS in Hot Summer and Cold Winter Region

A cooling tower-assisted ground source heat pump system is proposed to solve the problem of soil heat accumulation in areas with hot summers and mild winters. TRNSYS is used to establish the simulation model of the ground source heat pump system. Taking the ground source heat pump demonstration project in Nanchang City as the research object, the operation effect of the ground source heat pump is simulated and analyzed. The key parameters of the optimization system are proposed, and the operation time of the cooling tower is controlled. The optimization results show that the cooling tower can not only improve the system performance in a short time but also enable long-term stable and efficient operation of the refrigeration system, the compound ground source heat pump system optimized by the cooling tower has almost no soil heat accumulation, and the system performance has been improved. The optimal running time of the cooling tower is 3216~4344 h and 5424~6696 h, and the system running effect is the best at this time. The research results can provide a theoretical basis for the optimal design of the cooling tower auxiliary ground source heat pump system.

Exploiting Auxiliary Caption for Video Grounding

Video grounding aims to locate a moment of interest matching the given query sentence from an untrimmed video. Previous works ignore the sparsity dilemma in video annotations, which fails to provide the context information between potential events and query sentences in the dataset. In this paper, we contend that exploiting easily available captions which describe general actions, i.e., auxiliary captions defined in our paper, will significantly boost the performance. To this end, we propose an Auxiliary Caption Network (ACNet) for video grounding. Specifically, we first introduce dense video captioning to generate dense captions and then obtain auxiliary captions by Non-Auxiliary Caption Suppression (NACS). To capture the potential information in auxiliary captions, we propose Caption Guided Attention (CGA) project the semantic relations between auxiliary captions and query sentences into temporal space and fuse them into visual representations. Considering the gap between auxiliary captions and ground truth, we propose Asymmetric Cross-modal Contrastive Learning (ACCL) for constructing more negative pairs to maximize cross-modal mutual information. Extensive experiments on three public datasets (i.e., ActivityNet Captions, TACoS and ActivityNet-CG) demonstrate that our method significantly outperforms state-of-the-art methods.

Pseudo-Supervised Low-Light Image Enhancement With Mutual Learning

Low-light image enhancement (LIE) is important for many high-level vision tasks as the poor visibility of underexposed images can severely degrade the performance of the subsequent image recognition, analysis, etc. Although recent deep-learning-based LIE methods exhibit promising performance, most of them require a large number of paired training images, thereby limiting the practicability to real scenarios. In this paper, we propose a pseudo-supervised LIE method with the integration of mutual learning. Specifically, for the given low-light image, we first use a quadratic curve to generate a pseudo-clear image, which is served as the auxiliary ground truth for supervision, then the pseudo-paired images are simultaneously input to two parallel homogeneous branches to learn the expected enhanced result through the knowledge distillation of two branches via mutual learning. As both the generated image and the input low-light image underlies the desired solution, the mutual learning strategy enables the two branches learn from each other and produce the final results. Extensive experiments demonstrate that the proposed method outperforms most existing unsupervised LIE methods in terms of both qualitative and quantitative evaluations, and also achieves competitive performance against many supervised and semi-supervised methods.

Analysis of the calculation methods for shell circulating current and grounding current in 500 kV HGIS and the optimization of grounding scheme

The strong electromagnetic coupling between the wire and the shell of Hybrid Gas Insulated Switchgear (HGIS) will lead to a large induced current on the shell, which will further cause local heating of the outside shell. Moreover, the utilization of grounding wire to release this current may also lead to the problem of its heating and ground potential rise. This study is intended to further promote the calculation accuracy of the shell circulating current and grounding current of the 500 kV HGIS and also propose the proper grounding schemes. The simulation results show that the ground grid must be considered in the calculation model and the phase difference of the conductor current could be ignored when the three-phase spacing exceeded 7.5 m. Furthermore, the influences of shorting bars and ground grid on the simulation results were compared and analyzed, and the optimization of grounding scheme and corresponding suggestions were put forward. Generally, it was not recommended to erect shorting bars and auxiliary ground grids. But if the temperature rise exceeds the limit, the shorting bars can be added at the two ends of a HGIS branch and the auxiliary ground grid should be laid using materials with higher flow capacity.

Evaluation of the excitation spectra with diffusion Monte Carlo on an auxiliary bosonic ground state.

We aim to improve upon the variational Monte Carlo (VMC) approach for excitations replacing the Jastrow factor by an auxiliary bosonic (AB) ground state and multiplying it by a fermionic component factor. The instantaneous change in imaginary time of an arbitrary excitation in the original interacting fermionic system is obtained by measuring observables via the ground-state distribution of walkers of an AB system that is subject to an auxiliary effective potential. The effective potential is used to (i) drive the AB system's ground-state configuration space toward the configuration space of the excitations of the original fermionic system and (ii) subtract from a diffusion Monte Carlo (DMC) calculation contributions that can be included in conventional approximations, such as mean-field and configuration interaction (CI) methods. In this novel approach, the AB ground state is treated statistically in DMC, whereas the fermionic component of the original system is expanded in a basis. The excitation energies of the fermionic eigenstates are obtained by sampling a fermion-boson coupling term on the AB ground state. We show that this approach can take advantage of and correct for approximate eigenstates obtained via mean-field calculations or truncated interactions. We demonstrate that the AB ground-state factor incorporates the correlations missed by standard Jastrow factors, further reducing basis truncation errors. Relevant parts of the theory have been tested in soluble model systems and exhibit excellent agreement with exact analytical data and CI and VMC approaches. In particular, for limited basis set expansions and sufficient statistics, AB approaches outperform CI and VMC in terms of basis size for the same systems. The implementation of this method in current codes, despite being demanding, will be facilitated by reusing procedures already developed for calculating ground-state properties with DMC and excitations with VMC.

Airport sustainability through life cycle assessments: A systematic literature review

AbstractAnthropogenic climate change contributes to increased frequency and intensity of droughts, wildfires, storms, coastal sea level rise, and population displacements, in addition to causing lung and cardiovascular diseases from the emission of Criteria Air Pollutants (CAPs). The aviation sector is estimated to contribute 2%–3% of global anthropogenic Greenhouse Gas (GHG) emissions. This excludes GHG emissions from airport operation and maintenance activities due to limited research in the area. This systematic literature review examined the Life Cycle Assessment (LCA) carried out by previous studies on the environmental impacts of airport operation and maintenance activities. This allows to assess existing literature on the impacts of these activities; identify knowledge gaps in LCA based on the findings of the review; and propose areas for further research and improvement in mitigating the environmental impacts of airport operation and maintenance activities. A total of 11 papers were selected for thematic analysis and narrative synthesis following a systematic review process based on the research question which yielded a total of 263 peer‐reviewed research articles and dissertations on the topic. The findings of the review showed that knowledge gaps exist in the LCA of environmental impacts of Auxiliary Power Units (APU) and Ground Support Equipment (GSE) operations in the airport during aircraft turnaround time. Further research is suggested in the use of feasible and affordable alternative energy sources (electricity, compressed natural gas, liquefied petroleum gas, and hydrogen) at airports to reduce the environmental impacts associated with petrol‐ and diesel‐powered GSE and gate operations at airports.

Research on the Influence of Various Attribute Factors on Passive Interference in UHV Transmission Lines Based on Orthogonal Test

Considering the problem of passive interference caused by electromagnetic scattering effects of transmission lines to neighboring radio stations and other communication equipment, this paper refines the passive interference calculation model for UHV transmission lines. The solution calculation is carried out by the Method of Moments, and the law of passive interference effect of the tower structure, auxiliary angles, and ground roughness under different frequency incident waves, is summarized. By designing an orthogonal test, the degree of influence of the above attributing factors on passive interference results in the established joint model of three towers with two stall distances was explored by using Analysis of Variance. The results demonstrate that both auxiliary angles and rough ground show a pattern of enhanced electromagnetic scattering effect with increasing plane wave frequency in single-factor analysis. When multiple factors are combined, the rough ground has a significant effect on the results. This method effectively evaluates the passive interference influence factor while reducing the modeling and simulation engineering and provides a reference for the passive interference prediction in subsequent practical projects.

Manipulation of wave motion in smart nonlinear phononic crystals made of shape memory alloys

Thanks to the functional role of shape memory alloys (SMAs) in controlling the mechanical behavior of structures, researchers have started investigating the possibility of manipulating wave motion in phononic crystals using SMAs. While SMAs were used before to tune the wave propagation in linear phononic crystals, in this work, we aim to extend their utilization to nonlinear lattices. For this purpose, SMA helical springs are used to manipulate the dispersion curves and the location of stop-bands in weakly nonlinear monoatomic and diatomic lattice chains. Using Brinson’s formulation to describe the thermo-mechanical behavior of SMA wires and Lindstedt-Poincaré method to solve the derived governing equations, closed-form nonlinear dispersion relations in monoatomic and diatomic lattice chains are obtained and the effects of temperature-induced phase transformation and stiffness nonlinearity on the wave propagation are investigated. The results reveal that the dispersion curves of a weakly nonlinear monoatomic chain are formed at lower frequencies through the austenite-to-martensite phase transformation. Similarly, both the acoustic and optical branches of a diatomic lattice are moved to lower frequencies during the phase transformation in the cooling process. Therefore, the generated stop-bands in nonlinear diatomic lattices are also moved to lower frequencies. In addition, using auxiliary SMA ground springs, new classes of nonlinear monoatomic and diatomic chains exhibiting additional low-frequency attenuation zones are introduced. These low-frequency stop-bands are tunable and their frequency range can be modulated by exploiting the temperature-induced phase transformation in the SMA springs. The results obtained from analytic formulations are verified by numerical calculations and an excellent agreement is observed. Such tunability and the potential for adding stop-bands in low frequencies reveal that SMAs can be very helpful in designing nonlinear phononic and acoustic devices, such as vibration mitigators and wave filters with pre-defined attenuation zones.

A new design of substation grounding based on electrolytic cathodic protection and on transfer corrosion current

In this paper, zinc material is used as auxiliary anode grounding electrode and connected by flat steel to form grounding grid of electrolytic cell protection circuit, to prevent the main grounding grid from corrosion. At the same time, the paper designs to transfer the lead-down from the grounding grid to the auxiliary anode grounding grid, and to transfer the corrosion current to the auxiliary anode grounding grid. Several groups of zinc-iron electrodes were deeply buried in deep excavated soil outdoors to conduct simulated grounding grid protection tests. At the same time, the software simulation is carried out in the laboratory. Firstly, Rotating Disk Electrode (RDE) and Solartron electrochemical interface were used to compare the current-voltage curves of three cases (natural anode, passive cathode and active cathode), and the corrosion rates of the three cases were calculated. Secondly, ATP-EMTP simulation software is used to simulate the point voltage and current of the auxiliary anode grounding grid before and after the design of the transfer corrosion current. The simulation results show that passive electrolytic cathode has better corrosion protection. The auxiliary anode grounding grid design and the transfer corrosion current design can better prevent the main grounding grid from corrosion.

A new optimization design for grounding grid

In this paper, a new approach for designing groudging grid is proposed. The design is based on constracting an auxiliary annular grounding grid and transforming the lingtning rod’s grounding poing from main grounding grid to auxiliary grounding grid. Modal analysis and softwave simulataes is employed to obtain the transformed lightning current (and the voltage) and the reduced ressitance. The dual port model is used to calculate the impedance value of the grounding grid. The calculation results of the model are compared with the standard grounding body model EMF. At the same time, the relationship between the induced voltage of each point of the grounding grid and the distance of the lightning current injection point is studied by using the dual port model. The reduced resistance is simulated by building annular grounging grid model and square grounging grid model and making a comparison in performance betwen them. Farther, when there is a lingtning event, instead of providing a low impedance path by the main grounding grid, the design provide anther path by the auxilary grounding grid, which can transfer the lightning current into the auxilary grounding grid. All the model analysis and simulation results are presented and discussed in the paper.

Estimating wheat biomass from GF-3 data and a polarized water cloud model

ABSTRACTWheat is one of the staple crops of the world. With the wide application of remote-sensing methods in agriculture, the use of data from synthetic aperture radar has attracted increasing attention for monitoring wheat growth. Most of previous studies estimated wheat biomass based on a water cloud model (WCM). However, when no data are available on soil moisture content, the applicability of such models is greatly reduced because of insufficient parameters. Thus, this study proposed a new polarized water cloud model (PWCM) called APWCM, which is a physical model and no auxiliary ground data was needed including soil moisture data. APWCM and WCM model was compared to estimate the above ground biomass of wheat in two different study areas. The results revealed that the WCM has a slightly lower root mean squared error (RMSE = 131.63 g m−2, and 645.17 g m−2) in two different study areas. However, the APWCM has lower relative error (RE = 17.91%, and 13.53%) for wheat biomass estimation in areas with higher biomsass. The final result indicates that the APWCM can replace the WCM for estimating wheat biomass based on Gaofen-3 (GF-3) data when soil-moisture data are not available.

Emissions from auxiliary power units and ground power units during intraday aircraft turnarounds at European airports

It is widely known that emissions from aircraft engines, Auxiliary Power Units (APU) and ground handling equipment contribute to air pollution at airports. During the aircraft turnaround process, the main source of emissions is the APU. The use of the APU can be significantly reduced if the aircraft stand is equipped to supply external electrical power and pre-conditioned air to the cabin. This paper analyses the actual duration of APU and external power usage during intraday aircraft turnarounds at 125 airports during June 2015. The data is derived from flight data recording units of more than 200 short-haul, narrow-body jet aircraft, conducting some 25,195 aircraft turnarounds and thus provides the most detailed assessment of aircraft power usage available. A common practice is for the APU to be running for a short period on arrival at the stand (arrival-cycle) and then again for a short period prior to departure (departure-cycle). It is identified in this study that departure-cycle emissions are three times greater than arrival-cycle emissions. These emissions could be reduced if more accurate forecasts of departure times are available to flight crew. The provision of external ground power is found to reduce emissions by up to 47.6%. However, the study also highlights that when the source of external power is a diesel-fuelled mobile Ground Power Unit (GPU), there is a net doubling in emissions of hydrocarbons. APU usage is also observed to vary with outside air temperature (OAT) leading to possible increases in emissions of up to 6%.

Emissions of Airport Monitoring with Solar Occultation Flux-Fourier Transform Infrared Spectrometer

Both domestic and international aviation industries have experienced a boom, which results in a dramatic increase in emissions of the aviation industry in recent decades. Therefore, domestic and abroad scientists adopted different methods to measure emissions; however, there are no appropriate methods to measure the emissions of the whole airport. In order to provide data support for the relevant departments to take appropriate emission reduction measures, solar occultation flux-Fourier transform infrared spectrometer (SOF-FT-IR) is used to monitor the emissions of Beijing Capital International Airport. CO, CO2, C2H4, and CH2O are selected as the target gases and are quantitatively analyzed with the nonlinear least squares method to get the column concentration. Then, the flux can also be calculated by linking the wind velocity and direction with the column concentration. A comparison between the results measured by SOF-FT-IR and the results measured by the method published by the Intergovernmental Panel on Climate Change (IPCC) indicates that auxiliary power equipment and ground support equipment for the emission of the airport are also important emission sources besides the aircraft and the concentration distribution gives powerful and useful pieces of evidence to locate the emission sources. In order to decrease the contribution of the airport to the air pollution, the key point is to reduce the emissions of the APU and mobiles in the airport.

Estimation of Amazon River discharge based on EOF analysis of GRACE gravity data

River discharge is a critical component for understanding hydrological processes and sustainable management of water resources. The importance of discharge observation has increased due to its potential extreme variation resulting from the projected climate change and stronger variability of precipitation and temperature in some large basins. However, inherent difficulties in ground-based observations and decreasing number of gauge stations hinder accurate measurement of global river discharge and its spatio-temporal variations. Various remote sensing methods have been examined as alternatives, however, they require ground measurements to convert their proxy measurements into the actual river discharge. In this study, we estimate the discharge at the Óbidos station and the mouth of the Amazon basin using the water storage variations derived from GRACE gravity data without relying on any auxiliary ground observations. We extract the water mass signal along the main stem of the river by applying the Empirical Orthogonal Function (EOF) for water storage variations over the basin. The relative water storage variations along the main stem derived from the EOF decomposition are highly correlated with in-situ discharge at the Óbidos. However, in high water season, the GRACE-based discharge is estimated larger than the in-situ observations, and the difference is particularly significant during the 2009 extreme flood season. We argue that the in-situ river discharge in 2009 was underestimated due to the missed water volume for the flow detouring around the Óbidos gauge station during the high-flow event. Net river discharge of the Amazon Basin to Atlantic Ocean is also estimated, and its annual discharge is about 23% larger than that of the Óbidos. In particular, 2009 river discharge to Atlantic Oceans is estimated as 1050Gton.

Digital disaster evaluation and its application to 2015 Ms8.1 Nepal Earthquake

The purpose of the article is to probe the technique resolution of disaster information extraction and evaluation from the digital RS images based on the internet environment and aided by the social and geographic information. The solution is composed with such methods that the fast post-disaster assessment system will assess automatically the disaster area and grade, the multi-phase satellite and airborne high resolution digital RS images will provide the basis to extract the disaster areas or spots, assisted by the fast position of potential serious damage risk targets according to the geographic, administrative, population, buildings and other information in the estimated disaster region, the 2D digital map system or 3D digital earth system will provide platforms to interpret cooperatively the damage information in the internet environment, and further to estimate the spatial distribution of damage index or intensity, casualties or economic losses, which are very useful for the decision-making of emergency rescue and disaster relief, resettlement and reconstruction. The spatial seismic damage distribution of 2015 Ms8.1 Nepal earthquake, as an example of the above solution, is evaluated by using the high resolution digital RS images, auxiliary geographic information and ground survey. The results are compared with the statistical disaster information issued by the ground truth by field surveying, and show good consistency.

Effects of load following operational strategy on CCHP system with an auxiliary ground source heat pump considering carbon tax and electricity feed in tariff

Combined cooling, heating and power (CCHP) system plays a significant role in efficient usage of energy in field of small scale power system for application ranging from residence to utilities. In the paper, a new CCHP system is proposed which consists of a power generation unit (PGU), an absorption chiller, a storage tank and a ground source heat pump (GSHP) to substitute conventional electric chiller and auxiliary boiler to supply the deficient cooling or heating load. In the study, three basic load following strategies: following electric load (FEL), following thermal load (FTL) and following hybrid load (FHL) are employed to analyze the annual total cost (ATC), operational cost (COST), carbon dioxide emissions (CDE) and primary energy consumption (PEC) based on a case study of a regional energy system in Sino-Singapore eco-city. For the evaluated case, carbon tax and electricity feed in tariff are both considered to compare with the performances of following maximum electric efficiency of the PGU (Max-eff) strategy. The results show that the proposed system performed well on COST, CDE and PEC reduction and the ATC are all increased except that of Max-eff strategy with carbon tax and electricity feed in tariff. When carbon tax and electricity feed in tariff are considered, performances of the Max-eff strategy is the best. Otherwise, the application of FEL is better. Finally, for the Max-eff and FEL strategy, sensitivity analysis is performed and results are presented with varying of electricity and gas price.

The Research of High Voltage Auxiliary Power System Neutral Point Grounding Modes between the Nuclear Power Plant and Conventional Fossil Fuel Power Plant

<p>Currently, in power plants, the application of the extinction coil in high voltage auxiliary power system neutral point is less experienced. A research done on nuclear power plant and conventional fossil fuel power plant proved that using an auxiliary power system’s different characteristics was leading to different demands of the grounding modes. Thus, this research was done by selecting the grounding mode of high voltage auxiliary power system neutral point on the main nuclear power plants and the partial fossil fuel power plants together with the calculation of practical engineering, and optimal design schemes. The high voltage auxiliary power system neutral point grounding modes have been induced in the large-scale into the nuclear power plant and the conventional fossil fuel power plant. Methods in determining the neutral point grounding modes are used by analyzing the principles commonly used grounding modes and requirements of related codes. First, choose the suitable grounding mode according to the calculation result of capacitive current. Then, choose more conducive grounding mode to the operation of power plant according to the operation of technology equipment. The power is required from the configuration, connection of auxiliary power and the cut from the accident of auxiliary power. As some power plants which are under-construction will be putting into operation one after another, the whole set of perfect security arrangements and operating experiences will also be accumulated inevitably. As a conclusion, high voltage auxiliary power system neutral point grounding modes directly affect the running of the auxiliary power system and even affect the security of the nuclear safety and the operation of the power plant. I hope this article can play a role for reference on the selection of the auxiliary power system grounding modes.</p>

The Research of High Voltage Auxiliary Power System Neutral Point Grounding Modes between the Nuclear Power Plant and Conventional Fossil Fuel Power Plant

<p>Currently, in power plants, the application of the extinction coil in high voltage auxiliary power system neutral point is less experienced. A research done on nuclear power plant and conventional fossil fuel power plant proved that using an auxiliary power system’s different characteristics was leading to different demands of the grounding modes. Thus, this research was done by selecting the grounding mode of high voltage auxiliary power system neutral point on the main nuclear power plants and the partial fossil fuel power plants together with the calculation of practical engineering, and optimal design schemes. The high voltage auxiliary power system neutral point grounding modes have been induced in the large-scale into the nuclear power plant and the conventional fossil fuel power plant. Methods in determining the neutral point grounding modes are used by analyzing the principles commonly used grounding modes and requirements of related codes. First, choose the suitable grounding mode according to the calculation result of capacitive current. Then, choose more conducive grounding mode to the operation of power plant according to the operation of technology equipment. The power is required from the configuration, connection of auxiliary power and the cut from the accident of auxiliary power. As some power plants which are under-construction will be putting into operation one after another, the whole set of perfect security arrangements and operating experiences will also be accumulated inevitably. As a conclusion, high voltage auxiliary power system neutral point grounding modes directly affect the running of the auxiliary power system and even affect the security of the nuclear safety and the operation of the power plant. I hope this article can play a role for reference on the selection of the auxiliary power system grounding modes.</p>

Effects of Ground Grid Configuration of Two Neighbouring Distribution Substations on Ground Potential Rise in MEA’s Power System

This paper presents construction planning procedures for a new small (temporary) or permanent distribution substation to replace an existing distribution substation that is served as a small or permanent substation to supply the load of the existing distribution substation while it has not yet been removed. In the meantime when the ground grids of the two substations are electrically disconnected, the auxiliary grounding system of the existing distribution substation can create steep ground potential rise between the ground grids of the two substations and hence introduces a risk for those who are working nearby. It is therefore important to incorporate safety criteria described in terms of step and touch voltage into electrical designs without any potential electrical hazards. Modeling and simulation is carried out on the Current Distribution Electromagnetic interference Grounding and Soil structure (CDEGS) program. A sequential transition process from the existing distribution substation to a new distribution substation is suggested to comply with the IEEE standard 80-2000. The results in this paper could be served a guideline in grounding system design of distribution substation and modification of grounding standards in MEA’s power distribution system.