The Special Issue “Distributed Energy Resources Management 2018” includes 13 papers [...]

In recent years, most of the growth in electricity demand is covered by renewable and nuclear energy sources. However, electricity generation in fossil-fired power plants is also increasing resulting in the increase of CO2 emissions. Nuclear energy has to be considered as one of the available tools to accomplish CO2 emission reduction in electricity sector. Light water reactors (LWR) are currently the dominant nuclear technology but their intensive application in long-term period is constrained by available uranium fuel resources. Fast breeder reactors’ (FBR) technology is not used on a larger scale. Plutonium resources are limited, but do have the potential of stronger buildup if light water reactors, as the source of plutonium, are used on a larger scale. The appropriate dynamics for LWR/FBR buildup till the end of the 21st century is developed under assumptions of different LWR life times, and different uranium fuel resources available. The possible CO2 emission reduction is calcula... [more]

Atmospheric stability has been studied for decades. There are several methodologies that evolved over the years. In this study, a special experimental meteorological mast that has been erected to a complex site has been used to calculate dimensionless Obukhov length ( ζ = z L ) , dimensionless momentum ( φ m ), and heat coefficients ( φ h ). The results are compared with the ones from average value approaches: Richardson number, flux-profile (F-P) relations, and wind shear exponent methods. The results show that the estimated ζ values, using the bulk Richardson number, get along well with the reference ζ within the neutral and stable regimes. F-P relations and wind shear exponent methods result in the best agreement for stable and neutral regimes. Nevertheless, average oriented methods are not reliable for the other regimes.

In this paper, a discussion is presented concerning the combined uncertainty when measuring residual and additional losses in the efficiency evaluation of three-phase induction motors, by evaluating some experimental results obtained on a commercial motor. The IEC 60034-2-1 standard is considered, in comparison to a previous version of this standard requiring the estimation of residual losses instead of their measurement. A major goal is to investigate if the complex measurement method introduced in the present version of the standard is justified or not by processing the actually achievable uncertainty both in additional losses and in the overall efficiency measurement. Finally, some considerations are presented about additional issues concerning the classification of the tested motor, in comparison to the IE (International Efficiency) efficiency levels.

The mathematical model of composite reservoir has been widely used in well test analysis. In the process of oil recovery, due to the injection or replacement of the displacement agent, the model boundary can be moved. At present, the mathematical model of a composite reservoir with a moving boundary is less frequently studied and cannot meet industrial demand. In this paper, a mathematical model of a composite reservoir with a moving boundary is developed, with consideration of wellbore storage and skin effects. The characteristics of pressure transient in moving boundary composite reservoir are studied, and the influences of parameters, such as initial boundary radius, moving boundary velocity, skin factor, wellbore storage coefficient, diffusion coefficient ratio, and mobility ratio on pressure and production, are analyzed. The moving boundary effects are noticeable mainly in the middle and late production stages. The proposed model provides a novel theoretical basis for well test an... [more]

This paper presents a unique integrated approach to meter placement and state estimation to ensure the network observability of active distribution systems. It includes observability checking, minimum measurement utilization, network state estimation, and trade-off evaluation between the number of real measurements used and the accuracy of the estimated state. In network parameter estimation, observability assessment is a preliminary task. It is handled by data analysis and filtering followed by calculation of the triangular factors of the singular, symmetric gain matrix using an algebraic method. Usually, to cover the deficiency of essential real measurements in distribution systems, huge numbers of virtual measurements are used. These pseudo measurements are calculated values, which are based on the network parameters, real measurements, and forecasted load/generation. Due to the application of a huge number of pseudo-measurements, large margins of error exists in the calculation pha... [more]

This work reviews the state-of-the-art methodologies for the deterministic sensitivity analysis of nonlinear systems and deterministic quantification of uncertainties induced in model responses by uncertainties in the model parameters. The need for computing high-order sensitivities is underscored by presenting an analytically solvable model of neutron scattering in a hydrogenous medium, for which all of the response’s relative sensitivities have the same absolute value of unity. It is shown that the wider the distribution of model parameters, the higher the order of sensitivities needed to achieve a desired level of accuracy in representing the response and in computing the response’s expectation, variance, skewness and kurtosis. This work also presents new mathematical expressions that extend to the sixth-order of the current state-of-the-art fourth-order formulas for computing fourth-order correlations among computed model response and model parameters. Another novelty presented in... [more]

This paper reports the effect of high-pressure torsion (HPT) on the first hydrogenation of LaNi5. We found that, for loose powder, reduction of particle size has an effect of increasing the incubation time and decreasing the hydrogen capacity. A higher amount of HPT turns only marginally reduce the incubation time but has no effect on hydrogen capacity. In all cases, the first dehydrogenation and subsequent hydrogenation have the same kinetics, irrespective of the particle size or number of HPT turns. Therefore, for LaNi5, HPT has a beneficial effect only for the first hydrogenation.

Steam methane (CH4−H2O) reforming in the presence of a catalyst, usually nickel, is the most common technology for generating synthesis gas as a feedstock in chemical synthesis and a source of pure H2 and CO. What is essential from the perspective of further gas use is the parameter describing a ratio of equilibrium concentration of hydrogen to carbon monoxide (H/C=xH2/xCO). The parameter is determined by operating temperature and the initial ratio of steam concentration to methane SC=xH2O0/xCH40. In this paper, the author presents a thermodynamic analysis of the effect of green hydrogen addition to a fuel mixture on the steam methane reforming process of gaseous phase (CH4/H2)−H2O. The thermodynamic analysis of conversion of hydrogen-enriched methane (CH4/H2)−H2O has been performed using parametric equation formalism, allowing for determining the equilibrium composition of the process in progress. A thermodynamic condition of carbon precipitation in methane reforming (CH4/H2) with the... [more]

The exposure to chemicals in detergent factories, as some studies have shown, has a negative impact the health of workers’ respiratory systems. The aim of the study was to assess the lung function parameters of detergent factory workers and compare it with those of a group of non-chemical workers using spirometry. Methods: A comparative cross-sectional study was performed involving male detergent factory workers and a comparison group of non-chemical workers. An interviewer-administered questionnaire was used to record workers’ characteristics, and the data were entered to the spirometry device. The spirometry test was performed to assess workers’ lung functions; we recorded the forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, peak expiratory flow (PEF), forced expiratory flow between 25 and 75% of FVC (FEF25−75%), and lung age. Results: A total of 94 participants (28 detergent factory workers and 66 non-chemical workers) were included i... [more]

In the present study, the electrochemical behavior of antiviral drug umifenovir (Umi) and umifenovir encapsulated in phospholipids micelles (nanosome/umifenovir, NUmi) were investigated for the first time on screen-printed electrodes modified by carbon nanotubes. We have shown that Umi can be electro oxidized around the potential of +0.4 V in the concentration range of 50−500 µM (R2 = 0.992). Non-overlapping signatures of DNA and umifenovir (10−150 µM) permit to register interaction between umifenovir (or umifenovir encapsulated in phospholipids micelles), purine, and pyrimidine heterocyclic bases of DNA separately. The type of interaction is most likely via electrostatic interactions and groove binding in drug-DNA formed complex, as was revealed based on the values of binding constants Kb and the cathodic shifts of oxidation potentials for heterocyclic bases with increasing Umi or NUmi concentration. The negative values of Gibbs free energy (ΔG) for all nucleobases confirm the process... [more]

I4.0 promotes a future in which highly individualized goods are mass produced at a competitive price through autonomous, responsive manufacturing. In order to attain market competitiveness, organizations require proper integration of I4.0 technologies and manufacturing strategy outputs (MSOs). Implementing such a comprehensive integration relies on carefully selecting I4.0 technologies to meet industrial requirements. There is little clarity on the impact of I4.0 technologies on MSOs, and the literature provides little attention to this topic. This research investigates the influence of I4.0 technologies on MSOs by combining reliable MCDM methods. This research uses a combination of fuzzy DEMATEL and fuzzy TOPSIS to evaluate the impact of I4.0 technologies on MSOs. The fuzzy theory is implemented in DEMATEL and TOPSIS to deal with the uncertainty and vagueness of human judgment. The FDEMATEL was utilized to identify interrelationships and determine criterion a’s weights, while the fuzz... [more]

Biomass occupies a significant proportion of municipal solid waste. For the high-value processing of waste biomass, a hydrothermal-carbonization method was chosen because of the advantages of effective and mild conditions. Four typical types of waste biomass (banana peel, mangosteen peel, orange peel, and pomelo peel) were used in this work to prepare high-value carbon aerogels (CA) via hydrothermal-carbonization treatment for cracking ethanol. Four kinds of CA all had good performances in the ethanol cracking reaction and improved the yield of H2 from 21 wt% to about 40 wt%. The banana peel-based carbon aerogel (BPCA) showed the best performance in the reaction; it cracked ethanol and obtained 41.86 wt% of H2. The mechanism of ethanol cracking by CA was revealed: On one hand, the self-cracking of ethanol was improved due to the extension of residence time, which benefited from the abundant pores in CA. On the other hand, the heterogeneous reaction occurred on the surface of CA where t... [more]

Product recommendation systems are essential for enhancing customer experience, and integrating them with mobile apps is crucial for improving usability and fostering user engagement. This study proposes a hybrid approach that utilizes comparative facts from pairwise comparison data and comparison lists, with association rules as the method to formulate the recommendation system. The study employs a dataset from the New-Cars Database app, comprising 30,867 vehicle comparisons made by 5327 users across 40 car brands and 870 cars from 30 January 2015 to 2 April 2015. Two metrics are developed to measure the system’s output under varying support and confidence thresholds. The findings suggest that adjusting the support and confidence values can improve the breadth and depth of product recommendations. In addition, the unit of analysis can affect the recommendation system’s output, with comparison lists supplementing and expanding the exploration of potential outcomes. The proposed hybrid... [more]

The aim of this study was to compare the aromatic profile of plum spirits, obtained from the Požegača and Stanley varieties, as affected by different combinations of pre-distillation steps used in traditional and six modified production methods that are common in Serbian distilleries. Traditional plum spirits (produced from spontaneously fermented mashes of crushed plums with stones distilled after two months of storage) had the highest contents of ethyl acetate, benzaldehyde, and total acids, which resulted in the occurrence of an unpleasant solvent-like and stone-like odour and acidic taste. These sensory defects were overcome by the distillation of fermented mashes immediately after the completion of alcoholic fermentation. Depending on the combination of the pre-distillation steps, plum spirits from mashes distilled immediately after alcoholic fermentation were characterized by different aromatic profiles: closer to traditional (from spontaneously fermented crushed plums with/witho... [more]

Signaling molecules act as the links and bridges between endophytes and host plants. The recognition of endophytes and host plants, the regulation of host plant growth and development, and the synthesis of secondary metabolites are not separated by the participation of signaling molecules. In this review, we summarized the types and characteristics of signaling molecules in medicinal plants and the recent processes in intracellular conduction and multi-molecular crosstalk of signaling molecules during interactions between endophytic bacteria and medicinal plants. In addition, we overviewed the molecular mechanism of signals in medical metabolite accumulation and regulation. This work provides a reference for using endophytic bacteria and medicinal plants to synthesize pharmaceutical active ingredients in a bioreactor.

With the further innovation of chip technology, semiconductor integrated circuits have made irreplaceable contributions to the development of microelectronic systems [...]

Chinese tea has a long history, and the development level of tea mechanization in this country is in the leading position internationally. Equipment for the tea processing craft is one of the most widely used types in China; indispensable technology is used for high-quality tea in the relevant tea processing equipment. The performance of tea processing equipment is always a focus when it is being used. Meanwhile, research evaluating the performance of tea processing equipment has been rarely reported. Thus, it is important to find a methodology to evaluate the performance of equipment for the tea processing craft. In this paper, a new method of rough set theory, as well as a radar chart for quality evaluation of tea processed by different tea processing crafts, is created. Firstly, the important indexes of processed tea are presented, including moisture, tea polyphenols, free amino acids, caffeine, and vitamin C. Then, these indexes for nine different types of processed tea based on di... [more]

Although numerous investigations have revealed the gas physisorption characteristics of porous media, the essence of physisorption behavior of gas within nanoscale space is still indistinct. We speculated that the physisorption behavior of a complex molecular system (e.g., CH4 and CO2) exhibits a quantum effect due to the confinement effect of nanopores. Gas molecules occur in varied orbitals following certain probabilities and, therefore, have separate energy levels inside a nanoscale space. Energy level transition of molecules from excited state to ground state triggers gas physisorption, while non-uniform spatial distribution of energy-quantized molecules within nanopores dominates the gas physisorption behavior. The spatial distribution of gas molecules can be adjusted by temperature, pressure and potential energy field. Based on the quantum effect, we developed a physisorption equation from the perspective of quantum mechanics to re-understand the basic principles of gas physisorp... [more]

Acid fracturing is one of the effective techniques for developing low-permeability carbonate reservoirs economically. With the increasing reservoir depth, the reservoir temperature and closure pressure increase, posing new challenges to the acid system. In this paper, a high-temperature-resistant cross-linked acid system is selected, which maintains a viscosity above 80 mPa·s in the temperature range of 120 °C to 140 °C and can effectively reduce acid leak-off. The acid system can not only open the reservoir and ensure the extension of the fracture, but also reduce the reaction rate between the acid and the reservoir and increase the etching distance. The rock slab acid etching and conductivity tests show that the optimum injection rate is 50 mL/min, the rock etching morphology is channel type, and the conductivity remains above 110 D·cm. However, as the acid concentration decreases, the rock slab conductivity decreases considerably, especially at 10% acid concentration, where the clos... [more]

Cu/ZnO/Al2O3 catalyst with the addition of tri-promoters (Mn/Nb/Zr) was investigated with respect to their catalytic activity and stability in a prolonged reaction duration in methanol synthesis. Spent catalysts were characterized using N2 adsorption-desorption, FESEM/EDX, TEM, N2O chemisorption, and XPS for their physicochemical properties. The catalyst longevity study was evaluated at two days, seven days, and 14 days at 300 °C, 31.25 bar, 2160 mL/g.hr GHSV, and H2:CO2 at 10:1. The CO2 conversion and methanol yield decreased by about 5.7% and 7.7%, respectively, when the reaction duration was prolonged to 14 days. A slight reduction in catalytic activity under prolonged reaction duration was found due to thermal degradation.

This paper investigates how the pre-treatment of the growth solution with ultrasonic energy affects the annealing temperatures and the growth temperatures of zinc oxide (ZnO) nanorods. The ultrasonic pre-treatment of the growth solution resulted in the successful growth of ZnO nanorods at a very low annealing temperature of 40 °C. The size and density of ZnO nanorods were found to increase proportionally with the increasing duration of pre-ultrasonic treatment, as indicated by characterisations performed with a scanning electron microscope (SEM). At an annealing temperature of 40 °C, coupled with ultrasonic waves, the SEM results showed that ZnO nanorods’ length and diameter increased by 37 and 25%. A similar pattern was also observed at an annealing temperature of 60 and 80 °C, where the length and diameter of ZnO nanorods increased. In addition, the conductivity and acidity of the aqueous solution that had been sonicated were measured. The results showed that solution conductivity an... [more]

The molecular structure of cationic surfactants is closely related to their flotation performance. In this paper, three cationic surfactants with different head group structures were selected as collectors of kaolinite, and the substituent effects were studied by the DFT method. The DFT calculation results showed that increasing the number of substituents in the dodecylamine head group can significantly increase its surface and head group charge. Dodecylamine has the lowest LUMO orbital energy, so dodecylamine has the strongest electron attraction ability and the strongest interaction with kaolinite. Electron density differential showed that there was an area of electron aggregation between the collector and the surface of the kaolinite. The interaction energy of DDA on kaolinite surfaces was greater than that of the other two collectors, indicating that the adsorption of DDA on the surface of kaolinite was more stable. Flotation results showed that higher a kaolinite yield was obtaine... [more]

Wound healing is the process of skin and soft tissue repair following an injury. Angiogenesis is an essential process in wound healing and plays an important role in tissue regeneration. Ginseng is mainly composed of saponins and protopanaxadiol-based ginsenosides, namely Rb1, Rb2, Rc, Re, Rg1, and Rf. 20(S)-protopanaxadiol (PPD) and 20(S)-protopanaxatriol (PPT) are aglycones of ginsenosides produced by metabolic processes and heat treatment. This study aimed to investigate the wound healing effects of active ingredients of ginseng, namely ginsenosides and aglycones, in various cellular and animal skin wound models. The angiogenic effects of ginsenosides were investigated in human umbilical vein endothelial cells (HUVECs). All experiments were conducted at increased intracellular glucose concentrations and the induction of angiogenesis through tube formation was evaluated. Among the ginsenosides and aglycones used in this study, PPD showed the strongest wound-healing activity. Cell scr... [more]

Many oil wells in closed reservoirs continue to produce in the pseudo-steady-state flow regime for a long time. The principal objective of this work is to investigate the characteristics of two key pseudo-steady-state parameters—pseudo-steady-state constant (bDpss) and pseudo-skin factor (S)—for a well penetrated by a fracture with an azimuth angle (θ) in an anisotropic reservoir. Firstly, a general analytical pressure solution for a finite-conductivity fracture with or without an azimuth angle in an anisotropic rectangular reservoir was developed by using the point-source function and spatial integral method, and two typical cases were employed to verify this solution. Secondly, with the asymptotic analysis method, the expressions of pseudo-steady-state constant and pseudo-skin factor were obtained on the basis of their definitions, and the effects of permeability anisotropy, fracture azimuth angle, fracture conductivity and reservoir shape on them were discussed in detail. Results sh... [more]