Operation Scheme Research Articles

Integration of BESS in grid connected networks for reducing the power losses and CO[formula omitted] emissions: A parallel master-stage methodology based on PDVSA and PSO

This work addressed the problem of integration and operation of Ion-lithium batteries of different technical characteristics in grid-connected networks (GCN) for reducing the energy losses and CO2 emissions. To formulate the mathematical problem, nonlinear mathematical modeling was used, taking into account the previously mentioned objective functions and all the constraints that represent the operation of the grid in a scenario of variable photovoltaic generation and power demand. This paper proposed a master–slave methodology, which uses a parallel discrete version of the vortex search algorithm (PDVSA) for solving the problem of location and selection of the kind of battery in the GNC. The slave stage is entrusted to find the operation scheme of the batteries proposed for the master stage. This task is carried out by a particle swarm optimization algorithm (PSO) that defines the power to be supplied or stored for each battery. Using a matrix hourly power flow for calculating the effect in the objective function and constraints that represent the problem. As a test scenario, it was used a GCN of 33 buses and 32 lines that considered the photovoltaic generation and demand of Medellín-Colombia, and all technical and environmental indexes of the local grid operator. Six comparison methodologies were used from the literature and developed in this work to evaluate the effectiveness of the proposed methodology. Being all programming in MATLAB software, executing each one 1000 times with the aim to evaluate the performance in terms of solution, repeatability, and processing times. The results obtained demonstrating that the proposed PDVSA/PSO methodology achieved the best results in terms of solution, with reductions of 154.9094 kWh (6.23%) in energy losses and reductions of 0.0252 tons of CO2 (0.2548%) in pollutant gas emissions compared to the base case. Regarding repeatability, the PDVSA/PSO exhibits standard deviation values of 0.1383% for energy losses and 0.0034% for CO2 emissions.

Understanding Heterogeneous Passenger Route Choice in Municipal Rail Transit with Express and Local Trains: An Empirical Study in Shanghai

The express/local mode of municipal rail transit provides passengers with multiple alternatives to achieve more efficient and superior travel, in contrast to the conventional all-stop operation mode. However, the various route choices (including direct express trains, direct local trains, or transfers) covering different passenger groups pose a significant challenge to passenger flow assignment. To understand route choice behavior, it is crucial to measure the passenger heterogeneity (variability in individual and trip attributes) in order to propose targeted solutions for operation schemes and service planning. This paper proposes a hybrid model by integrating structural equation modeling and the mixed logit model under express/local mode to estimate the impact of passenger heterogeneity on route choice. An empirical study with revealed preference and stated preference surveys carried out in Shanghai revealed how individual and trip attributes quantitatively impact the sensitivity of factors in route choice. The results show that age and trip purpose are more significant factors. Compared to the control group, the probability of express trains is reduced by 10.22% for the elderly and by 11.36% for non-commuters. Our findings can provide support for more reasonable operation schemes and more targeted services.

Investigation on the operating capacity expansion through parallel schemes of reciprocating-switcher energy recovery device for desalination: Simulation, verification and parameterization

Parallel operation is a significant and feasible method to compensate the insufficient capacity of single reciprocating-switcher energy recovery device (RS-ERD) in membrane desalination system. To grasp the operating characteristics in capacity expansion, three parallel schemes of RS-ERD, single-operation scheme, two-parallel scheme and three-parallel scheme, are investigated through the numerical simulation, experimental verification and theoretical parameterization. Results indicate that, the two-parallel scheme and three-parallel scheme achieve the flowrate continuity of low-pressure seawater and the flowrate fluctuation amplitudes in parallel RS-ERDs decrease by 50 % and 83 % respectively when compared with single-operation scheme. Parallel operation schemes also broaden the flowrate range with high efficiency for RS-ERD. To ensure the 95 % energy recovery efficiency, two-parallel and three-parallel schemes expand the maximum flowrates to 140 m3/h and 210 m3/h in contrast with the 70 m3/h of single-operation scheme. In addition, the two-parallel and three-parallel schemes of RS-ERD realize the much lower specific energy consumption (SEC) of 2.11 kWh/m3 and 2.09 kWh/m3 than the 2.23 kWh/m3 in single-operation scheme which contributes to the operating costs savings about 63,830 CNY and 75,778 CNY in one year. This research provides a new perspective in capacity expansion through the parallel operation of energy recovery devices.

Present and Future Challenges of the Special VAT Scheme for Travel Agents

The special scheme for travel agents and tour operators was designed as a simplification measure to avoid multiple registration obligations for businesses in this sector and to allocate VAT revenues to the Member State of consumption. However, the scheme raises a number of practical difficulties, largely due to the different interpretations of the scheme in the Member States, which makes it difficult for taxable persons to manage. In this article, the author discusses some of these practical difficulties and points out what he believes may be possible future solutions.

Development of constant switching frequency model predictive control for DFIG-based wind energy conversion system in standalone and grid connected operation

This paper presents a constant switching frequency (CSF) model predictive control (MPC) for a doubly-fed induction generator (DFIG)-based wind energy conversion system (WECS) in standalone and grid-connected operations. The system comprises a cascade connection of a rotor side converter (RSC) and a grid side converter (GSC) with a common DC-link. A battery energy storage system (BESS) is also connected to the common DC-link via a bi-directional dc–dc converter (BDDC). The RSC is controlled through CSF-model predictive current control (CSF-MPCC) scheme in both standalone mode (SAM) and grid-connected mode (GCM) of operations. The GSC control employs the CSF-MPCC scheme in grid-connected operation, whereas CSF-model predictive voltage control (CSF-MPVC) scheme is implemented in standalone operation. Moreover, the power balance is achieved by controlling the BDDC using MPCC to discharge or charge the BESS in response to surplus or deficient power generation. The effectiveness of the proposed control approach for DFIG-based WECS in both SAM and GCM is verified through MATLAB-based simulation and experimental results under different dynamic conditions like variable wind velocity changing from 12 m/s to 8 m/s, different grid demands from 3 kW to 1.5 kW and load change of 4 kW to 6.5 kW. Moreover, the robustness of the proposed control is corroborated by parametric sensitivity, time delay, and grid unbalance, along with its low-voltage ride-through (LVRT) capability during an LLLG fault.

К вопросу применения горных комбайнов типа KSM при отработке Северо-Западного участка Эльгинского каменноугольного месторождения

The paper presents the results of research that aims to increase the cost efficiency of the Elga open pit mine, which develops a coal deposit of the same name located in the permafrost zone, by introducing the continuous flow process technology with the use of surface miners that allow selective excavation of rock seams and plies, thereby reducing their dilution, instead of the cyclic method based on drilling and blasting operations. Illustrations and detailed information are provided on the physical, geographical and geological features of the field site, the degree of its exploration, the geological structure, reserves, climatic, geocryological and mining conditions of the deposit, physical and mechanical properties of the overburden rocks and coals, a technological scheme of the mining operations at the strip mine. The key mining and geological indicators of the NorthWest section of the developed deposit are given; and the technical capacity of the proposed surface miner is defined. Estimated qualitative indicators of coal production are presented in the graphic form, including the losses, dilution and ash content at the bulk and selective mining of individual seams. It is emphasized that the highest rates of losses and dilution of the mined coal are observed when mining a seam with the most complex structure. The obtained results will allow to justify the optimal technological parameters to apply the continuous flow process technology based on application of the KSM-type surface miners when developing complex seams in different areas of the Elga deposit, which will ultimately increase the cost efficiency of the mining company. Based on the performed researches, a conclusion is made on the efficiency of using surface miners for development of the deposit.

Genetic programming expressions for effluent quality prediction: Towards AI-driven monitoring and management of wastewater treatment plants

Continuous effluent quality prediction in wastewater treatment processes is crucial to proactively reduce the risks to the environment and human health. However, wastewater treatment is an extremely complex process controlled by several uncertain, interdependent, and sometimes poorly characterized physico-chemical-biological process parameters. In addition, there are substantial spatiotemporal variations, uncertainties, and high non-linear interactions among the water quality parameters and process variables involved in the treatment process. Such complexities hinder efficient monitoring, operation, and management of wastewater treatment plants under normal and abnormal conditions. Typical mathematical and statistical tools most often fail to capture such complex interrelationships, and therefore data-driven techniques offer an attractive solution to effectively quantify the performance of wastewater treatment plants. Although several previous studies focused on applying regression-based data-driven models (e.g., artificial neural network) to predict some wastewater treatment effluent parameters, most of these studies employed a limited number of input variables to predict only one or two parameters characterizing the effluent quality (e.g., chemical oxygen demand (COD) and/or suspended solids (SS)). Harnessing the power of Artificial Intelligence (AI), the current study proposes multi-gene genetic programming (MGGP)-based models, using a dataset obtained from an operational wastewater treatment plant, deploying membrane aerated biofilm reactor, to predict the filtrated COD, ammonia (NH4), and SS concentrations along with the carbon-to-nitrogen ratio (C/N) within the effluent. Input features included a set of process variables characterizing the influent quality (e.g., filtered COD, NH4, and SS concentrations), water physics and chemistry parameters (e.g., temperature and pH), and operation conditions (e.g., applied air pressure). The developed MGGP-based models accurately reproduced the observations of the four output variables with correlation coefficient values that ranged between 0.98 and 0.99 during training and between 0.96 and 0.99 during testing, reflecting the power of the developed models in predicting the quality of the effluent from the treatment system. Interpretability analyses were subsequently deployed to confirm the intuitive understanding of input-output interrelations and to identify the governing parameters of the treatment process. The developed MGGP-based models can facilitate the AI-driven monitoring and management of wastewater treatment plants through devising optimal rapid operation and control schemes and assisting the plants’ operators in maintaining proper performance of the plants under various normal and disruptive operational conditions.

Analysis of the integral zeolite molecular sieve process for helium CPS application

Zeolite Molecular Sieves (ZMSs) are commonly adopted in tritium handling facilities for impurity removal from gaseous streams, particularly for tritiated water trapping. Several activities have been conducted to characterize the adsorption and desorption behaviour of the sieving materials. Instead, less attention has been put on the analysis of the integral process comprising the adsorption of the tritiated humidity, the regeneration of the molecular sieve and the recovery of the desorbed water. Focusing on the application for the EU-DEMO helium Coolant Purification System (CPS), this work presents a process simulator relying on a MATLAB dynamic model of the ZMS bed and on a RELAP5/MOD3.3 model for the regeneration loop. The dynamic model can simulate both the adsorption and regeneration modes of the ZMS by providing the temperature and the adsorbate concentration profile along the column, while the thermal-hydraulic model is used to assess the conditions of the regeneration loop. By coupling the outcomes of the two models it is possible to establish the effective regeneration efficiency of the process and the amount of the tritiated water recovered. For the case of helium CPS, the analysis demonstrates the feasibility of the proposed operative scheme and the capabilities of the regeneration procedure to ensure a 74.4 % regeneration efficiency of the ZMS bed.

Earliest Prepared core technology in Eurasia from Nihewan (China): Implications for early human abilities and dispersals in East Asia

Organized flaking techniques to obtain predetermined stone tools have been traced back to the early Acheulean (also known as mode 2) in Africa and are seen as indicative of the emergence of advanced technical abilities and in-depth planning skills among early humans. Here, we report one of the earliest known examples of prepared core technology in the archaeological record, at the Cenjiawan (CJW) site in the Nihewan basin of China, dated 1.1 Mya. The operational schemes reconstructed from the CJW refit sets, together with shaping patterns observed in the retouched tools, suggest that Nihewan basin toolmakers had the technical abilities of mode 2 hominins, and developed different survival strategies to adapt to local raw materials and environments. This finding predates the previously earliest known prepared core technology from Eurasia by 0.3 My, and the earliest known mode 2 sites in East Asia by a similar amount of time, thus suggesting that hominins with advanced technologies may have migrated into high latitude East Asia as early as 1.1 Mya.

Research on an optimal operation model for cascade pumping stations based on simulations

AbstractCascade pumping stations (CPS) consume a large amount of energy every year in lifting districts. To obtain a reasonable and feasible operation scheme for CPS, this paper proposes an optimal operation model for CPS based on simulations. A one‐dimensional unsteady flow model of open canals was coupled with the optimal operation model of CPS, and an energy‐dominated optimization was proposed with the water level of the inlet pool as the coordinated variable. The optimization model was solved by using the catch‐up method and the nondominated sorted genetic algorithm II (NSGA‐II). The optimal operation method was validated and implemented in the first‐stage and second‐stage pumping stations of the Zuncun Irrigation Project by lifting water from the Yellow River in Shanxi province. The results showed that the proposed optimization model can reduce the energy consumption of the CPS by 4% compared with the actual operation. In addition, the optimal operation model of the CPS coupled with simulation can realize the dynamic balance of flow by stabilizing the inlet pool level to operate within a safe range. The energy consumption of the CPS can be reduced by keeping the water level of the intake pool as high a level as possible.

Substantiating the rational parameters for a complicated non-transport system when mining low-thickness fireclay deposits

The paper examines a complicated non-transport system for mining a gently sloping fireclay deposit using ESH-10/70 dragline excavators. The research purpose is to substantiate the technological scheme of stripping operations and determine their parameters to reduce the strip-mining costs. Theoretical research is performed using the following methods: methods of scientific analysis of theoretical research, as well as practices of project and production organizations; mining-geometric calculations; variant method for comparing and selecting a mining system. As a result, the dependence of the excavator block mining velocity on the entry way width has been determined, which makes it possible to study the relationship between mining and stripping equipment in time. The change in the re-excavation coefficient depending on the width of the dragline excavator entry way has been studied and its rational value has been determined. The practical value of the research results is in the substantiation of an effective system for mining a gently sloping fireclay deposit.

Justification for mining overburden without the use of conveyor transport at the Pivnichnyi open pit of the Pokrovskyi mining and processing enterprise

The current state of mining operations in the open pits of the Pokrovsky mining and processing enterprise has been analyzed, where the shortcomings of existing technological schemes have been identified. Technical and organizational criteria have been identified that must be met by technological schemes for overburden and mining operations for the open-pits of the Pokrovsky mining and processing enterprise, where conveyor transport is used. Five technological schemes have been proposed for the Pivnichnyi open-pit, which provide for the reallocation of the height of overburden benches and the movement of overburden only to internal dumps without the use of conveyors. The dependences of the height of the internal dump and its resulting angle of slope on the re-excavation factor for the proposed technological schemes were obtained. The indicators have been calculated at which the most operating efficiency of mining and transport equipment for the Pivnichnyi open-pit of the Pokrovsky mining and processing enterprise (MPE) will be achieved and complete extraction of overburden rocks with cross movement to the internal dump without the use of conveyor transport will be ensured, and the production capacity of the quarry is also given according to the demand for ore.

Operational scheme for predicting tropical cyclone wind radius based on a statistical–dynamical approach and track pattern clustering

AbstractAn operational scheme for predicting the symmetric R30 and R50 of tropical cyclones (TCs) in the western North Pacific was developed using a statistical regression method and track pattern clustering (four clusters). The statistical–dynamical model employs multiple linear regressions of two to eight variables at each cluster and forecast lead time. The dependent variable for prediction was the change in the 5‐kt wind radius (R5)—a proxy of TC size—relative to the initial time. The performance of the model was compared for the training (2008–2016) and testing (2017–2018) periods. The effect of clustering on TC size prediction was evaluated by comparing the performance of the non‐clustering and clustering models. The clustering model improved the prediction of TC size by 3%–24% at all lead times during the training period, especially with a significant improvement of up to 43% in Cluster 2. In Cluster 2, because most TCs tend to develop strongly and continue to increase in size, it greatly reduced the variability in TC size through clustering, allowed for smarter predictor selection, and ultimately improved TC size prediction. In the real‐time R30 and R50 predictions for the 2017 and 2018 TCs, the error of the clustered model was 18%–19% less than that of the non‐clustered model. The analysis results revealed that the real‐time prediction errors of the current model increase when the TC tracks are difficult to classify into specific clusters, the predicted environments and TC tracks are inaccurate, and the size and intensity of a TC rapidly increase.

Aggregated Operation Scheme for Distributed Photovoltaic and Energy Storage System Enabling Multi-Service Provision

Aggregated Operation Scheme for Distributed Photovoltaic and Energy Storage System Enabling Multi-Service Provision

Analysis of the social and physical factors affecting irrigation scheme performance: The case of the Omo Gibe river basin in the Southern Nations, Nationalities and Peoples’ Region, Ethiopia

AbstractOne hundred years ago, irrigation development began in Ethiopia, but the efficiency and sustainability of the developed scheme have remained very low. As a result, this study aimed to assess the factors that most frequently affect a scheme's performance. The study analysed general physical and social performance indicators. Structural and social factors were used to identify the most common causes of underperformance of the schemes in the Omo Gibe river basin. Frequency analysis was conducted using Statistical Package for the Social Sciences (SPSS). The relative operational scheme performance and relative irrigated area were 32 and 31%, respectively. The beneficiary to target performance was 63%. Structural and social factors such as flooding and subsequent damage to the under sluice and lack of participatory approaches during scheme development were the most common determinants of irrigation scheme performance. Hence, catchment development and community participation in scheme development are crucial for mitigating irrigation scheme underperformance.

Electric flight operations for interisland mobility

Several studies have shown that flying electric between the so-called ABC-islands in the Caribbean (i.e., Aruba, Bonaire and Curaçao) is feasible with the upcoming first generation of battery-electric aircraft. This paper presents a real-world case study that deals with the technical and operational characteristics of electric flight in that region. With that purpose, the Aruba Airport Authority (AAA) commissioned this investigation, which involved numerous local stakeholders, such as airlines, energy providers and navigation services. This study involves two commuter electric aircraft under development, aiming to investigate how they fit in the current operational scheme of three local airlines and three conventional aircraft types in terms of technology, capacity, schedule, performance, CO2 emissions and fuel costs. Conclusions indicate that a transition to batter-electric aircraft is feasible with regards to the aforementioned criteria and with the current technology and energy density of batteries.

LIGHTWEIGHT ENVIRONMENTS FOR TESTING SPEED AND RELIABILITY OF SOFTWARE BASED ON OPERATING SYSTEM LEVEL VIRTUALIZATION

An environment for performance software testing has been described, based on the use of containerization technology through the use of appropriate software (Docker or others) on the one hand, and a tool for measuring performance and carrying out load testing such as ApacheBench or similar. The advantage of containerization technology for achieving the goal was evaluated. It is shown that in this case, the test environment can be deployed on different computers separately, rather than being deployed centrally. This provides following advantages: less cost in terms of computing resources compared to other ways of deploying environments on local computers. Certain types of environment configurations can be easily distributed and replicated between individual computers and workstations through the distribution and application of prepared configuration files. Compared to cloud environments, this approach does not require additional material costs for support. The scheme of operation of such an environment for non-functional testing has been analyzed.. The environment also allows you to simulate more complex configurations, for example, to study the operation of various load balancing algorithms/systems. The created testing environment was tested on the example of performance of testing web applications. It showed that the created environment allows you to calculate the approximate response time of the application and the presence of failures depending on the number of users who use the application at the same time. Also, load testing allows you to calculate the normal and critical number of application users and predict and prevent potential failures. The mechanism for creating test environments considered in this work can be used to build models that are necessary for studying and/or modeling certain types of software testing based on loads, load balancing algorithms between workstations, and others. Since such an approach can be used on almost any personal workstation with relatively small requirements for computing resources and the deployment and distribution of environments is quite simple, such an approach can be implemented not only in business, but also in universities for courses that involve the use similar environments.

Prediction of Specific Fuel Consumption of a Tractor during the Tillage Process Using an Artificial Neural Network Method

In mechanized agricultural activities, fuel is particularly important for tillage operations. In this study, the impact of seven distinct parameters on fuel usage per unit of draft power was examined. The parameters are tractor power, soil texture index, plowing speed, plowing depth, width of implement, and both initial soil moisture content and soil bulk density. This study investigated the construction of an artificial neural network (ANN) model for tractor-specific fuel consumption predictions for two tillage implements: chisel and moldboard plows. The ANN model was created based on the collection of related data from previous research studies, and the validation was performed using actual field experiments in clay soil using a chisel plow. The developed ANN model (9-22-1) was confirmed by graphical assessment; additionally, the root-mean-square error (RMSE) was computed. Based on the RMSE, the results demonstrated a good agreement for specific fuel consumption per draft power between the observed and predicted values, with corresponding RMSE values of 0.08 L/kWh and 0.075 L/kWh for the training and testing datasets, respectively. The novelty of the work presented in this paper is that, for the first time, a farm machinery manager can optimize tractor fuel consumption per draft power by carefully controlling certain parameters, such as initial soil moisture content, tractor power, plowing speed, implement width, and depth of plowing. The results show that the input parameters make a significant contribution to the output over the used data with different percentages. Accordingly, the contribution analysis showed that the implement width had a high impact on tractor-specific fuel consumption for both plows at 30.13%; additionally, the chisel and moldboard plows contributed 4.19% and 4.25% in predicting tractor fuel consumption per draft power. This study concluded that practical useful advice for agricultural production can be achieved through optimizing fuel consumption rate by selecting the proper levels of affecting parameters to reduce fuel costs. Moreover, an ANN model could be used to develop future tractor fuel-planning schemes for tillage operations.

Experimental study and performance evaluation of an air source heat pump (ASHP) system with a frost-free evaporator

The air source heat pump (ASHP) is operated in a low temperature and high humidity working environment. There is always a lot of frost forming on the outdoor heat exchanger, which hinders the heat transfer rate of the heat exchange surface, leading to the decrease of performance of the ASHP system. This paper presents a new type of frost-free evaporator for ASHP system. The heat transfer zone of the evaporator is composed of three parts: non-packing zone, plain finned-tube falling film zone and horizontal smooth tube bundle falling film zone. The experimental system of the frost-free evaporator is established, and the reliability of the experimental data is verified. The effects of refrigerant flow rate, inlet air temperature, fan frequency and solution spray mode on energy efficiency ratio, heat transfer expansion coefficient, air side pressure drop and exergy loss of the evaporator are studied. The performance of the evaporator is evaluated. The results show that with the increase of inlet air flow and temperature, the energy efficiency ratio of frost-free evaporator increases by about 8%–12%, and the air side pressure drop also increases. As the inlet air temperature increases from −10 to 15 °C, the heat transfer expansion coefficient of evaporator decreases by about 3%–6%, indicating that the increase of inlet air temperature will lead to an increase of sensible heat transfer ratio and a decrease of latent heat transfer ratio. The results also show that compared with no spray mode and continuous spray mode, the intermittent spray mode is more recommended as a feasible operation scheme to realize the continuous, efficient and stable operation of the new evaporator.

DEVELOPMENT OF AN EXPERIMENTAL INSTALLATION WITH A BUNKER-FEEDER AND ITS DESCRIPTION

In the article, after the ginning process in cotton ginning enterprises, ginned seeds are analyzed. A device is recommended for extracting the seeds that have fiber that can be spun from inside them (non-ginned), and the working scheme and principle of operation of the device are presented.