The recent study was concerned with employing the finite element method for heat and mass transfer of MHD Maxwell nanofluid flow over the stretching sheet under the effects of radiations and chemical reactions. Moreover, the effects of viscous dissipation and porous plate were considered. The mathematical model of the flow was described in the form of a set of partial differential equations (PDEs). Further, these PDEs were transformed into a set of nonlinear ordinary differential equations (ODEs) using similarity transformations. Rather than analytical integrations, numerical integration was used to compute integrals obtained by applying the finite element method. The mesh-free analysis and comparison of the finite element method with the finite difference method are also provided to justify the calculated results. The effect of different parameters on velocity, temperature and concentration profile is shown in graphs, and numerical values for physical quantities of interest are also g... [more]

To better understand the mechanism influencing the periodic lattice structures in gas turbine blade cooling, these numerical simulations present a systematic comparison of the effects in cases involving pin-fin, Kagome, and BCC lattice arrays on film-cooling effectiveness under three blowing ratios (i.e., M = 0.5, 1.0, and 1.5). The results indicate that the introduction of lattice array structures improves film-cooling effectiveness within the whole streamwise range, especially downstream of the film hole. With an increase in the blowing ratio, the superiority of lattice array structures relative to those without a lattice becomes increasingly evident. The local film-cooling effectiveness can be increased, to a maximum of about 100%, under a blowing ratio of 1.5. The secondary flow induced by the lattice array structure at the internal flow channel increases the TKE and accelerates the development of vortices in the film cooling hole. Using the lattice array model, the improvement of... [more]

Simulation based studies for operational energy system analysis play a significant role in evaluation of various new age technologies and concepts in the energy grid. Various modelling approaches already exist and in this original paper, four models representing these approaches are compared in two real-world hybrid energy system scenarios. The models, namely TransiEnt, µGRiDS, and OpSim (including pandaprosumer and mosaic) are classified into component-oriented or system-oriented approaches as deduced from the literature research. The methodology section describes their differences under standard conditions and the necessary parameterization for the purpose of creating a framework facilitating a closest possible comparison. A novel methodology for scenario generation is also explained. The results help to quantify primary differences in these approaches that are also identified in literature and qualify the influence of the accuracy of the models for application in a system-wide analy... [more]

Energy and climate policies play an increasingly important role in the world in the era of climate change and rising energy prices. More often, the importance of the development of the energy sector and climate protection is seen from the point of view of the expenditures that will need to be absorbed in the economy, with the potential for increased energy prices. However, it should be remembered that this is also related to the issue of fuel poverty and the inability to meet basic energy needs by parts of society. The aim of the paper is to assess the importance of macroeconomic policy instruments in reducing fuel poverty, using Poland as an example. It will be examined whether and how the government influenced this phenomenon (directly or indirectly), through which instruments, and which instruments (fiscal, monetary or energy-climate policy) played the most important role in shaping the scale of fuel poverty in Poland, with an emphasis on the role of monetary and fiscal policy instr... [more]

The optimal allocation of protective devices is a serious issue in an electrical power system; in order to reduce the possibility of faults, the protection devices should be optimally placed. The paper presents a continuous genetic algorithm (CGA) for the optimal allocation of directional relays for the efficient energy minimization in a radial distribution system (DG). The algorithm is flexible to use for the changes and improvements in the optimal location for a DG unit and can optimize the energy consumption in the radial distribution system. The proposed algorithm has been implemented on IEEE 33 and 69-bus system using MATLAB (R2014b, MathWorks). Low energy consumption is a common design objective in an energy-constrained distribution system. Engineers, power utilities, and network operators can profit from the proposed methodology to enhance the use of DG in distribution networks.

This work evaluates the effect of feedstock type and composition on the conversion of lignin to liquid by solvolysis with formic acid as hydrogen donor (LtL), by analyzing the yields and molecular composition of the liquid products and interpreting them in terms of both the type and the preprocessing of the lignocellulosic biomass using chemometric data analysis. Lignin samples of different types and purities from softwood, hardwood, and grasses (rice straw and corn stover) have been converted to bio-oil, and the molecular composition analyzed and quantified using GC-MS. LtL solvolysis was found to be a robust method for lignin conversion in terms of converting all samples into bio-oils rich in phenolic compounds regardless of the purity of the lignin sample. The bio-oil yields ranged from 24−94 wt.% relative to lignin input and could be modelled well as a function of the elemental composition of the feedstock. On a molecular basis, the softwood-derived bio-oil contained the most guaia... [more]

An index on the gas market commonly refers to the average price of a certain trading product, e.g., over the period of one month. Index-based sourcing is a widely-used habit in modern gas business. Risks are reduced by averaging prices over the purchasing period. Due to the significant volume, there have been many attempts to ”beat the index”, i.e., to design a strategy that, over time, offers cheaper prices than the index. Here, we use neural networks to identify n, n∈N, optimal shopping points. Both classification- and forecasting-based strategies are tested to decide on each trading day if gas should be purchased or not. Thereby, we use the Front Month index based on prices from the Dutch Title Transfer Facility as an example. Regarding cumulative performance, all but a very simple myopic algorithm are able to outperform the index. However, each strategy has its flaws and some positive results are due to the price increase during 2021. If one opts for an active sourcing strategy, th... [more]

Currently in Europe, road freight transport is characterized by the most dynamic advancement. Year after year, we may observe an increase in the amount of transported goods. The paper presents the emissions of gaseous exhaust components such as CO, THC, and NOx as well as fuel consumption in freight transport. The emission analysis was performed for the entire transport cycle covering the handling of the goods with forklifts and carriage with a heavy-duty truck. The investigations were performed under actual conditions of operation using a Portable Emission Measurement System (PEMS). The fuel mileage was determined using the carbon balance method. The test routes were designed so as to reproduce the transport-logistic system typical of small towns. The setting for the tests was a town located in central Poland near the A2 motorway constituting part of the trans-European logistic network with multiple locations of logistic centers. In order to present the real emissions during handling,... [more]

This paper presents a data-driven approach for the prognosis of the gradual behavioural deterioration of conveyor belts used for the transportation of pallets between processing workstations of discrete manufacturing systems. The approach relies on the knowledge of the power consumption of a conveyor belt motor driver. Data are collected for two separate cases: the static case and dynamic case. In the static case, power consumption data are collected under different loads and belt tension. These data are used by a prognostic model (artificial neural network (ANN)) to learn the conveyor belt motor driver’s power consumption pattern under different belt tensions and load conditions. The data collected during the dynamic case are used to investigate how the belt tension affects the movement of pallets between conveyor zones. During the run time, the trained prognostic model takes real-time power consumption measurements and load information from a testbench (a discrete multirobot mobile a... [more]

The sedimentary characteristics of the Neogene in the eastern Liaodong area are poorly studied, which restricts the oil and gas exploration in this area. Based on the current seismic, logging, drilling, and core data, we have studied the sequence stratigraphy and sedimentary characteristics of the Neogene in the eastern Liaodong area. Ultimately, we identified the controlling factors of sedimentation and established the depositional model. In this study, six sequence boundaries of the Neogene were identified and can be divided into five third-order sequences. The sedimentary evolution can be divided into four stages: braided river delta, meandering river delta with a low sand-stratum ratio, meandering river delta with a high sand-stratum ratio, and meandering river delta. Both the palaeotectonic movements and paleoclimate changes of the Neogene influence the periodical fluctuation of the lake level and then control the vertical evolution of the sedimentary types. The paleogeomorphology... [more]

Positive displacement machines present a well-known major drawback that is the oscillation in delivered flow rate. This paper presents two active solutions for reducing the flow ripple generated by a pump with an external device actuated by means of a piezo-stack actuator. The work is focused on a theoretical analysis, with the aim of collecting information about the performance of the solutions proposed and their main advantages and drawbacks. The active methods proposed involve a cylindrical actuator connected to the delivery line of the pump. The piston could be actuated directly by a piezo-stack actuator or by a differential pressure modulated by a proportional piezo actuated valve. The actuators were modelled and a control algorithm based on Least Mean Square algorithm was used to achieve the adaptability for both systems at different operating conditions. The developed mathematical model permits to define the great potential of these solutions that can drastically reduce the flow... [more]

This paper proposes a novel control strategy to alleviate the impulsive current for Uninterruptible Power Supply (UPS), which is designed based on the theory of virtual synchronous generator (VSG) and dynamic switching method. The power quality of UPS will become distortion when the instantaneous impulsive load is imposed on UPS. Especially, the output current of UPS will increase quickly in short time. In order to maintain the uninterrupted output voltage and reduce the distortion of output voltage of UPS under the action of instantaneous impulse load, Dynamic switching method is proposed to resist impulse load with large scale impulse current, Meanwhile, the VSG control strategy is adopted to deal with the slow power switching and provide virtual inertia for the system, so that the output voltage of UPS can remain uninterrupted and stable. Finally, simulation and experimental results show that this method can effectively suppress the impulse current, reduce the output voltage distort... [more]

A novel cross−series connection of two five−phase permanent magnet synchronous motors (FPMSM) supplied by single inverter can halve the number of required power units and current sensors. This, along with a decoupling control strategy for FPMSMs in series based on an improved dual−frequency vector modulation (DFV−SVPWM) and a flux−linkage torque ripple suppression method with current compensation are proposed in this paper, each of which have great significance for multi−unit industrial equipment. The third harmonic flux−linkage will produce torque ripple in the FPMSM in series, which has an adverse effect on accuracy. In this paper, a synchronous decoupling mathematical model of dual−series FPMSM with harmonic flux−linkage is established to analyze the decoupling relationship between torque and current. In addition, an enhanced DFV−SVPWM with higher modulation ratio is proposed for the decoupling control of double motors in series. Furthermore, based on the torque influence of two ser... [more]

Currently, companies in the energy sector are focus on sustainable growth, although they face many challenges, including the peculiarities of their operations. One of the features of companies in the energy sector is the need for effective communication with the media and the public. This is of paramount importance due to the current trends and challenges in the energy sector, the market requirements and the low level of development in such companies. The object of this study invovles the employees of the communication departments of energy sector companies, while the subject is the intensification of their activities based on the use of motivational tools. The authors chose the tools of the game theory, which is a game that the company and employees of the project team engage in when implementing information and communication projects. The study developed a method for motivating the employees of communication departments, which based on the game theory, allows the formation of many po... [more]

The growing share of renewable energies needs more flexible services to balance their intermittency and variance. The existing coal fired units and electrical energy storage (EES) systems may play an important role in delivering flexible services. The value of their flexibility services, along with the value of renewable energies, has to be analyzed from the perspective of the power system, in which the capacity costs and operation costs of renewable energy power units, EES systems, and thermal power generation units have to be taken into consideration. An optimal model is built to analyze the renewable energy integration and the flexibility services delivered by the EES systems and thermal power units in a power system. Taking the existing thermal power units and EES systems in North China Power Grid as an instance, the overall cost of the grid is examined for the penetration of renewable energies and flexible service provision. The results show that the growing shares of renewable en... [more]

As one of the most appealing options for large-scale energy storage systems, the commercialization of aqueous zinc-ion batteries (AZIBs) has received considerable attention due to their cost effectiveness and inherent safety. A potential cathode material for the commercialization of AZIBs is the manganese-based cathode, but it suffers from poor cycle stability, owing to the Jahn−Teller effect, which leads to the dissolution of Mn in the electrolyte, as well as low electron/ion conductivity. In order to solve these problems, various strategies have been adopted to improve the stability of manganese-based cathode materials. Among those, the doping strategy has become popular, where the dopant is inserted into the intrinsic crystal structures of electrode materials, which would stabilize them and tune the electronic state of the redox center to realize high ion/electron transport. Herein, we summarize the ion doping strategy from the following aspects: (1) synthesis strategy of doped mang... [more]

Several review studies exist in the literature about monitoring, fault detection, and diagnosis of power transformers. However, they are general approaches in terms of power transformers. Some only focus on applying a specific class of techniques, but again, for general power transformers. Other reviews focus on applying different technologies such as fiber optics, thermal cameras, and vibration sensors, but all within the perspective of general power transformers. A significant question remains: among all types of power transformers, which specific techniques should be used, and why are they more adequate? What are the uncertainties that can decrease their precision? What about the balance, in terms of costs, associated with applying a certain technique and the return needed for a particular type of transformer? In this context, this paper is not only a literature review of well-known problems related to power transformers. Here, we do not just center on large power transformers (100... [more]

This work evaluates the influence of the inoculum type, the pre-consumption of the residual substrate and the ratio of blanks’ headspace volume to working volume (Hv Wv−1, 0.6 to 10) on Biochemical Methane Potential (BMP) measurements when methane is monitored by gas chromatography. Different inocula were tested: digested sewage sludge—DSS, granular sludge—GS and fresh dairy manure—DM. Microcrystalline cellulose was used as the substrate. BMP surpassed the maximum theoretical value (BMPmax = 414 L kg−1) when methane produced in the blanks was not discounted, showing that degassing cannot stand alone as an alternative to the procedure of discounting the inoculum’s background production. Still, when the residual substrate concentration is high (e.g., in DM), degassing is mandatory because methane produced from its digestion will conceal the methane produced from the substrate in the BMP determination. For inocula with a low residual substrate (e.g., GS), short degassing periods are recom... [more]

Recently, the use of novel renewable energy has attracted attention for suppressing the generation of carbon dioxide to prevent global warming. There is growing interest in energy reduction in buildings using solar energy because of its ease of use and repair and excellent maintenance. Therefore, in this study, air-based Photovoltaic thermal (PVT) systems, which can increase the utilization of solar energy, are compared with the existing PV system through measurement. PVT systems can increase the amount of power generation by lowering the temperature of the panel using air passing through the lower part of the panel. It is also possible to use the heated air obtained from the panel as indoor heating or for supplying hot water in a building. As a result of measuring the performance of existing PV panels and PVT panels under the same weather conditions, the power generation efficiency of PVT panels through which air passes increases compared to PV panels. Overall, an air-based PVT system... [more]

This paper presents an advanced methodology for restoration of the electric power transmission system after its partial or complete failure. This load-optimized restoration is dependent on sectioning of the transmission system based on artificial neural networks. The proposed methodology and the underlying algorithm consider the transmission system operation state just before the fallout and, based on this state, calculate the power grid parameters and suggest the methodology for system restoration for each individual interconnection area. The novel methodology proposes an optimization objective function as a maximum load recovery under a set of constraints. The grid is analyzed using a large amount of data, which results in an adequate number of training data for artificial neural networks. Once the artificial neural network is trained, it provides an almost instantaneous network recovery plan scheme by defining the direct switching order.

(1) Background: The present development of transport networks focusses on the better management of fuels and energy and the preservation of the environment. To fulfill these desiderates, some countries have already reconsidered the deployment plans of new highways. This research studies the feasibility of less polluting, quasi-self-powered, intelligent highway infrastructure functional blocks accommodating functions for the future introduction of smart wireless sensor grids and connected autonomous vehicles. Subject of investigation are the possibilities of energy harvesting, and the intelligent management of resources. (2) Methods: the research investigates the main technologies for energy harvesting and recommends an optimal solution. It also proposes a framework for the intelligent, AI-based management of energy and the use of an optimized backup solution relying on 5G beamforming for energy supply of the local wireless sensing network devices; (3) Results: recommendations are made... [more]

The collapse deformation of shale has a significant influence on the exploitation process. Experimental analysis has indicated a correlation coefficient range from 0.9814 to 0.9981 and the established sample regression formula could be used to express the relationship between the dynamic elastic modulus and static elastic modulus of shale specimens. Based on the twin shear unified-strength theory, where coefficient b was considered to express the effect of intermediate principal stress, with the deduced regression formula, the unified solution of major principal strains describing a critical collapse of the shale shaft wall was derived. The results showed that the intermediate principal stress had a significant influence on the major principal strain, describing the critical collapse of the shale shaft wall. At the same depth, the critical collapse major principal strain increased with the increase in the b values. With the change in b value from 0 to 1, the calculated difference in cr... [more]

The variation in the two-phase flow parameters in a cylindrical body of new geometry and principle of operation are considered for a device for separating solids from air flow, solving the problem of numerical flow modeling. The aim of this research was to analyze the changes in the parameters of a multi-channel cylindrical cyclone in a mathematical model and to compare it with the results of the examined physical model. Studies on the numerical modeling of cyclones are reviewed, and models and equations for complex vortex flow description are applied. Differential equations were numerically solved by the finite volume method using the standard turbulence models of k−ε and RNG k−ε. Numerical modeling of the velocities, pressures, and volumes of both phases of the two-phase flow was performed. The simulation of the volume distribution of the second phase (glass particles) in the cyclone structure at flow rates of 10.9 m/s, 13.9 m/s, and 21.9 m/s was performed. The values obtained were c... [more]

Thailand is an agricultural country with several agro-industrial by-products that can be processed into fuels. Although producing ethanol from agro-industrial by-products is an interesting option, the process of distilling ethanol from fermented agricultural products requires a high temperature to increase the ethanol concentration from 10% to 95%. In this research, solar ethanol distillation equipment incorporating a solar parabolic collector with a vacuum heat absorber tube to increase efficiency by reducing heat loss was designed and developed. An electronic device was used to control the distillation process, maintain the required temperature, and make suitable adjustments to the solar radiation acceptance angles of the parabolic solar collector. Ethanol dilution at concentrations of 10%, 15%, and 20%, and Sato (Thai Rice Wine) were used as the reactant in the distillation process. The result of distilling ethanol distillation with a semi-automatic control using a vacuum-tube parab... [more]

Conservation through voltage reduction (CVR) aims to reduce the peak load and energy savings in electric power systems and is being deployed at various utilities. The effectiveness of the CVR program depends on the load characteristics, i.e., the sensitivity of the load to voltage variation, and voltage regulation device settings. In the current literature, there is a lack of discussion on the CVR factor calculation using different measurements, and there is a lack of method for active power loss estimation using substation measurements. This paper provides insights into CVR factor calculation based on the measurements captured at the substation and those at the load location. This paper also proposes a new method based on curve fitting and artificial neural network to estimate the active power loss using input active power, input reactive power and input voltage at the substation. The CVR comparison study conducted in this paper helps in understanding the factors affecting CVR factor... [more]