Energy retailers that sell energy at fixed prices are at risk of bankruptcy due to instantaneous fluctuations in wholesale electricity prices. Energy derivatives, e.g., electricity options, can be purchased by energy retailers then sold to customers as one potential risk-mitigation tool. A class of energy retailers that trade energy derivatives, including the electricity option, the carbon option and the green certificate, is considered in this paper. In terms of energy retailers, a strategy that can maximize the value of the purchased energy derivatives over a period of time and minimize the risk due to the stochastic price fluctuations is developed. Firstly, the dynamic prices of the electricity option as well as the carbon option are described by stochastic differential equations, and the dynamic prices of the green certificate are described by ordinary differential equations. Historical price data are used to obtain the parameters of both stochastic and ordinary differential equati... [more]

The life of the hearth is the main limiting link of the campaign of a blast furnace. As the equipment for holding molten iron in the furnace, the high-temperature molten iron is in direct contact with the refractory, which makes the refractory have a larger temperature increase. If the temperature gradient inside the refractory is large, it generates large thermal stress and causes the refractory to crack. Blast furnace gas and molten iron intrude into the gap, which directly causes melting erosion and other chemical erosion with carbon bricks. It aggravates the erosion degree of the furnace and seriously affects the production life of the furnace. Therefore, the furnace often occurs with different types of severe depression erosion in the late service of the blast furnace. In this study, the calculation model of the thermal fluid-solid coupling considering the molten iron flow and the solidification of molten iron was established. This calculation model was applied to study thermal st... [more]

This paper addresses the problem of coexistence of synchronization and anti-synchronization (CSAS) for a class of switched chaotic systems by adaptive control method, where the switched system is realized by unified chaotic systems under arbitrary switching signal. Firstly, necessary and sufficient conditions for the CSAS of the chaotic systems are proposed from two perspectives, one is by analyzing the parity of the system expression, and the other is by decomposing the system. Secondly, according to the obtained necessary and sufficient conditions, two algorithms are given to search the synchronization variables and anti-synchronization variables in the chaotic systems. Thirdly, the CSAS of the switched chaotic system can be achieved by a designed adaptive global controller with only one input channel under the arbitrary switching signal. Finally, the numerical simulation results verify the validity and effectiveness of the method we obtained.

The strength aspect of clay soil is a critical concern in practical engineering design. Electroosmosis (EO) has been adopted as a foundation treatment technology in some projects to increase the strength of soft clay. In order to widen the understanding on shear strength performance of EO-treated soil, the behavior of EO-treated soft clay using electrokinetic geosynthetics (EKG) as electrodes under the effect of water immersion was evaluated and compared with that of vacuum preloading (VP) treated soft clay under similar conditions. The main finding was that the EO-treated soil when immersed in water offered more resistance to the change in average water content than VP-treated soil. The average shear strength of EO-treated soil fell by 36.6% during 4 extra days of immersion. When the immersion time was extended to 10 days, the average shear strength fell by 65.4%. In contrast, the immersion time had little influence on the shear strength of VP-treated soil. Hence, if EO-treated soft c... [more]

In this study, a series of g-C3N4 nanosheets were prepared by various thermal oxidative etching times from four different precursors (urea, melamine, dicyandiamide and thiourea). The physicochemical properties of these g-C3N4 nanosheets were analyzed in detail using scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence emission spectra, Fourier transform infrared spectroscopy (FTIR), Brunauer−Emmett−Teller (BET) analysis and ultraviolet-visible diffuse reflectance. The results revealed that the g-C3N4 nanosheets obtained a thinner layer thickness and larger specific surface area, with an extension of thermal oxidative etching time. Meanwhile, sulfamethazine (SMZ), one of the most widely used sulfonamides, was used to evaluate the photocatalyst activity of the g-C3N4 nanosheets prepared in this study. Compared to other g-C3N4 nanosheets, urea-derived g-C3N4 nanosheets under 330 min thermal oxidative etching showed the highest photocatalytic activity for SMZ unde... [more]

Gas content is an important parameter for evaluating coalbed methane reservoirs, so it is an important prerequisite for coalbed methane resource evaluation and favorable area optimization to predict the gas content accurately. To improve the accuracy of CBM gas content prediction, the Bayesian hyper-parameter optimization method (BO) is introduced into the random forest algorithm (RF) and gradient boosting decision tree algorithm (GBDT) to establish CBM gas content prediction models using well-logging data in the Zhengzhuang block, south of Qinshui Basin, China. As a result, the GBDT model based on the BO method (BO-GBDT model) and the RF model based on the BO method (BO-RF model) were proposed. The results show that the mean-square-error (MSE) of the BO-RF model and the BO-GBDT model can be reduced by 8.83% and 37.94% on average less than that of the RF and GBDT modes, indicating that the accuracy of the models optimized by the BO method is improved. The prediction effect of the BO-GB... [more]

Yogurt is known as a healthy food, but some synthetic additives that are commonly added to it can be one of the factors that restricts yogurt’s consumption. The aims of this study were to prepare and evaluate yogurts with the addition of spray-dried, anthocyanin-rich colorant extracted from jabuticaba (Myrciaria cauliflora Mart.) skin. The concentrated extract was spray-dried using maltodextrin (20 g/100 g w/w) as a carrier and added to yogurts in the concentrations of 0.5, 1.0, 1.5, and 2.0 g/100 g w/w. The yogurts were stored for up to 28 days under refrigeration and periodically evaluated. Except for the yogurts to which 1.5 g of extract was added, all samples had a slight pH reduction in the first 7 days of storage. Throughout the yogurts’ storage period, the anthocyanin and a* values were slightly reduced (p < 0.05), indicating some anthocyanin instability. The rheological behavior was typical for yogurts, but the casein gel network was probably disrupted by the jabuticaba extr... [more]

Once a chemical production accident occurs in a chemical plant, it often causes serious economic losses, casualties, and environmental damage. Statistics show that many major accidents in the production and storage of chemicals are mainly caused by human factors. This article considers the influence of the human factor and proposes a quantitative analysis model of a chemical plant based on a Bayesian network. The model takes into account the main human factors in seven aspects: organization, information, job design, human system interface, task environment, workplace design, and operator characteristics. The Bayesian network modeling method and simulation were used to predict the safety quantitative value and safety level of the chemical plant. Using this model, we can quickly calculate the safe quantitative ratio of each factor in the chemical plant. Through the safety quantitative value, safety level, and sensitivity analysis, the safety hazards of chemical companies can be discovere... [more]

The complete characteristics of centrifugal pumps are crucial for the modeling of hydraulic transient phenomena occurring in pipe systems. However, due to the effort required to obtain these curves, pump manufacturers typically only provide basic information, particularly when the pump operates under normal conditions. To acquire the full characteristic curves based on the manufacturer’s normal performance curve, a machine learning (ML) model is proposed to predict full, complete Suter curves using a pump’s specific speed with the known parts of the Suter curve. The training data for the model are sourced from the available Suter curves from laboratory experiments. Subsequently, the proposed ML model combines several types of regression models in an attempt to find the most accurate prediction in terms of the root mean square error (RMSE). The result proved highly efficient, as the experiments attained a maximum RMSE value of 0.032 across the three categories of centrifugal pumps based... [more]

For a PEMFC to work better, adding baffles to a flow channel can improve reactant transfer. As a result, the work starts by developing a 3-D numerical model for the vanadium redox flow battery (VRFB) using COMSOL Multiphysic Simulation Software. By incorporating baffles into the serpentine flow channel, it is possible to simulate changes in ion concentration and terminal voltage. The findings indicate that the battery efficiency will be impacted by adding baffles. The authors also studied the effect of baffle height and baffle count. The baffle height of 0.9 times the channel height and baffle number of 9 has a better performance on the battery. There are four cases for installing nine baffles and four arranging types in the entire serpentine flow using such baffle height and number. In Case 4, baffles are placed uniformly at the location of channel numbers 1, 9, and 17 in the serpentine flow path. It has a better voltage and ion concentration reaction than the other cases. The unit te... [more]

The baseline plan of terminals will be impacted to a certain extent after being affected by uncertain events, such as vessel delay and unscheduled vessel arrival, resulting in disorderly terminal operations, wasted resources, and reduced loading and unloading efficiency, which further aggravates terminal congestion. To effectively cope with the disturbance of terminal operations by the above uncertain events and improve the operational efficiency of container terminals, this paper investigates the integrated rescheduling problem of berth allocation and quay crane assignment with vessel delay and unscheduled vessel arrival. Two steps are designed to deal with uncertainty shocks. The first step is to determine the rescheduling moment by using a rolling time-domain approach. The second step is to establish a rescheduling model and design an improved genetic algorithm(IGA) to obtain a rescheduling solution using various rescheduling strategies at the rescheduling moment. Moreover, through... [more]

Anaerobic digestion (AD) of sewage sludge can be optimised by adding trade wastes (TWs) because of their nutrient content and boost in biogas formation if non-inhibitory. However, some components in TWs might have an inhibitory impact, such as nitrogen compounds, sulphate, heavy metals, metalloids, halogens and organic pollutants (e.g., phenol). This study aimed to understand the impact of TWs on the co-digestion with sewage sludge to identify appropriate TW loads for sustainable AD operation. The composition of 160 TWs was evaluated and the constituents with potential to cause inhibition or toxicity were tested in bio-methane potential (BMP) tests. The compounds studied in BMP tests included ammonia, zinc, copper, aluminium, mercury, arsenic, chloride, sulphate and nitrate. An improvement was observed at concentrations 2−746 mg Zn/L, 1066−2821 mg Cl/L as zinc sulphate and sodium chloride in biogas production, and 2−746 mg Zn/L, 162 mg SO4/L, 25 mg Hg/L as zinc sulphate, sodium chlorid... [more]

Brittle damage is a key factor restricting tool life extension. The peridynamic (PD) theory was applied to explain and predict the brittle damage of the near-field of the cutting edge of a cemented carbide microgroove turning tool (CCMTT) for the first time in this study, and the PD modeling of the complex surface was realized. The results showed that the PD modeling accuracy of the CCMTT can reach ±3.4%. The displacement of material points in the near-field of the cutting edge of the CCMTT is caused by the combined effect of the external load and the internal interaction force, and the former is dominant. There is no linear relationship between the displacement and the calculation time; instead, there are fluctuations and a maximum increase in the material point displacement in the main cutting direction. Only microdisplacements of material points in the near-field of the cutting edge occur under the given cutting conditions. The accumulation of microcracks caused by microdisplacement... [more]

Because of their high nutritional value, the demand for scallops is increasing year by year. In the process of improving people’s living standards, the ready-to-eat characteristics and dry sales characteristics of this product make its shelling process particularly important in the production process. However, the mechanism of ultra-high pressure shelling has not yet been clarified. Therefore, in-depth study of the structural change of the scallop connection interface is of vital importance to explore the mechanism of ultra-high pressure shelling and the development of intelligent equipment from the mechanical point of view. The obturator muscle fibers and the inner surface materials of the shell at the obturator muscle scar of the scallop at 100, 200 and 300 MPa were obtained for Raman spectrum, Fourier-transform infrared spectrum and scanning electron microscopy analysis. The results showed that under the pressure of 200 MPa, the degree of protein denaturation of scallop adductor mus... [more]

Using the mixture of carbonized rice husk and shungite from the Kazakhstan Koksu deposit and the experimentally determined oil sorption capacity from contaminated soil with oil originating in the Karazhanbas oil field, a set of Artificial Neural Network (ANN) models were built for sorption predictions. The ANN architecture design, training, validation and testing methodology were performed, and the sorption capacity prediction was evaluated. The ANN models were successfully trained for capturing the sorption capacity dependence on time and on a carbonized rice husk and shungite mixture ratio for the 10% and 15% oil-contaminated soil. The best trained ANNs revealed a very good prediction capability for the testing data subset, demonstrated by the high coefficient of the determination values of R2 = 0.998 and R2 = 0.981 and the mean absolute percentage errors ranging from 1.60% to 3.16%. Furthermore, the ANN sorption models proved their interpolation ability and utility for predicting th... [more]

The topic of Industry 4.0 is more actual for various companies worldwide. Its impact is anywhere in company and government areas. Due to the individual parts of Industry 4.0, such as digitalization and robotization, we express changes impact on human resource management, where the most changes are defined. This contribution is focused on human resource management in the context of the application of Industry 4.0 in engineering companies operating in the Czech Republic and Germany. The main objective of the paper is to define potential connections between Industry 4.0 and its areas with the forfeiture of professions and preparedness for potential job changes. We employed a primary research approach with in-depth interviews and a questionnaire survey to reach a defined goal. The interviews were aimed at top managers and a questionnaire survey of ordinary employees and students/temporary workers. According to the gained results, there exist relevant statistical dependencies between Indust... [more]

Liquified natural gas (LNG) is a clean primary energy source that is growing in popularity due to the distance between natural gas (NG)-producing countries and importing countries. The large amount of cold energy stored in LNG presents an opportunity for sustainable technologies to recover and utilize this energy. This can enhance the energy efficiency of LNG regasification terminals and the economic viability of the LNG supply chain. The energy stored in LNG in the form of low temperatures is referred to as cold energy. When LNG is regasified, or converted back into its gaseous form, this cold energy is released. This process involves heating the LNG, which causes it to vaporize and release its stored energy. The current state-of-the-art techniques for LNG cold energy utilization, including power generation, air separation, traditional desalination, and cryogenics carbon dioxide (CO2) capture are discussed in this review. While most of the current LNG cold energy utilization systems a... [more]

The increasingly intense consumption of plastics and, above all, their improper disposal in the environment are causing serious environmental concerns. Great efforts have been made for the development of new methods aimed at facilitating and speeding up the identification and sorting of different materials in the plastic recycling process. In this field, new strategies based on fluorescent tagging have been developed. This work concerns the synthesis and characterization of new fluorescent copolymers of polyethylene (PE) and polystyrene (PS), which are among the most produced and consumed plastic materials. The synthesized copolymers are potentially suitable for use as fluorescent markers of PE and PS. Ethylene-co-N-pentenyl carbazole (P(E-co-PK)) and styrene-co-4-(N-carbazolyl)methyl styrene (P(S-co-SK)) copolymers were prepared by Ziegler−Natta and free radical polymerization, respectively. If excited at 300 nm, both P(E-co-PK)s and P(S-co-SK)s give fluorescence emissions resulting i... [more]

The issue of ever-increasing amounts of waste activated sludge (WAS) produced from biological wastewater treatment plants (WWTPs) is pointed out. WAS can be effectively reduced in the anaerobic digestion (AD) process, where methanogens break down organic matter and simultaneously produce biogas in the absence of oxygen, mainly methane and CO2. Biomethane can then be effectively used in gas turbines to produce electricity and power a part of WWTPs. Hydrodynamic cavitation (HC) has been identified as a potential technique that can improve the AD process and enhance biogas yield. Rotary generators of hydrodynamic cavitation (RGHCs) that have gained considerable popularity due to their promising results and scalability are presented. Operation, their underlying mechanisms, parameters for performance evaluation, and their division based on geometry of cavitation generation units (CGUs) are presented. Their current use in the field of wastewater treatment is presented, with the focus on WAS... [more]

The effects of contact conditions at the wire−die interface on the temperature distribution of the specimen and die are investigated to understand the wire drawing process. Finite element analysis and experiments are performed to analyze the temperature distribution of a drawn wire and die based on different contact conditions using a low-carbon steel wire. The maximum temperature (Tmax) of the die decreases as the contact heat transfer coefficient at the wire−die interface increases, whereas that of the wire increases with the contact heat transfer coefficient. The Tmax of the die and wire decreases with the thermal conductivity of the die. As the thermal conductivity of the die increases, the heat generated by friction is rapidly absorbed into the die, and the Tmax of the die decreases, thus resulting in a decrease in the surface temperature of the wire. The Tmax of both the die and wire linearly increases with the friction factor. In particular, the Tmax of the die more sensitively... [more]

This paper deals with the analysis of leakage characteristics of the proportional directional valve. These characteristics distinguish a real directional valve from an ideal one. The ideal directional valve is characterized by zero leakage due to its perfect geometry. The investigated element is the three-position four-way proportional directional valve with zero spool lap and feedback from the spool position. The spool position is measured by the inductive position sensor and processed by external electronics. Internal leakage occurs due to axial and radial clearances between the spool and the sleeve. The magnitude of axial clearances that occur at throttle edges and their effect on the directional valve leakage is the subject of research. The blocked-line pressure sensitivity curve, the leakage flow curve and the center flow curve are determined by experiment. Individual characteristics are determined for different working fluid temperatures and different supply pressures. The flow t... [more]

anion channelrhodopsin 1 (GtACR1) is a widely used inhibitor of optogenetics with unique conductance mechanisms and photochemistry. However, the molecular mechanism of light-gated anion conduction is poorly understood without a crystal structure for the intermediate state. In this study, we built the dark-state model based on the crystal structure of retinal and isomerized the model by twisting the C12-C13=C14-C15 dihedral step by step using molecular dynamics simulation. The conformational changes revealed the all-trans to 13-cis photoisomerization of the retinal chromophore cannot open the channel. There is no water influx, and a pre-opened K-like intermediate after photoisomerization of retinal is formed. During the opening of the ion channel, proton transfer occurs between E68 and D234. Steered molecular dynamics (SMD) and umbrella sampling indicated that the E68 and D234 were the key residues for chloride-ion conducting. We propose a revised channel opening pathway model of GtACR1... [more]

The purpose of this article is to point out the need to use software simulation tools in industrial practice to optimize the production process and assess the economic effectiveness of investment, including risk. The goal of the research is to find an optimal investment variant to ensure an increase in the production volume of at least 50% and to achieve the maximum economic efficiency of the investment, even considering the risk. The article presents a comprehensive approach that enables the achievement of the set research goal. The selection of the optimal version of the investment is carried out in three steps. Firstly, the versions of the investment variants are assessed from the production point of view using the program Tecnomatix Plant Simulation. Subsequently, the versions of the investment variants are assessed from an economic point of view and from a risk point of view. Economic efficiency is assessed using the financial criteria net present value (NPV), profitability index... [more]

Simulated moving bed (SMB) chromatography is a highly efficient adsorption-based separation technology with various industrial applications. At present, its application has been successfully extended to the biochemical and pharmaceutical industrial sectors. SMB possesses the advantages of high product purity and yield, large feed treatment capacity, and simple process control due to the continuous operation mode and the efficient separation mechanism, particularly for difficult separation. Moreover, SMB performs well, particularly for multi-component separation or complicated systems’ purification processes in which each component exhibits similar properties and low resolution. With the development of the economy and technology, SMB technology needs to be improved and optimized to enhance its performance and deal with more complex separation tasks. This paper summarizes the typical variants or modifications of the SMB process through three aspects: zone variant, gradient variant, and f... [more]

This paper represents a detailed techno-economic analysis of a typical commercial-scale catalytic decarboxylation process of naphthenic acids over HZSM-5 zeolite. Simulation of the process has been performed in ASPEN Plus®. The performance of the modeled unit was compared to experimental results data from a similar plant. Two models were developed for the proposed industrial plant based on continuous flow reactors; the first is based on a fluidized bed reactor, and it was modeled as a continuous stirred tank reactor (CSTR) unit, and the second is a semi-regenerative process that consists of three fixed-bed reactors with intermediate preheaters and are modeled as three plug flow reactors (PFR). The outcome of the economic analysis of the two proposed commercial scale reactors of a decarboxylation process of a capacity of 11,000 bbl/day showed that the CAPEX, including the total equipment cost for the fluidized bed reactor plant and semi-regenerative process plant, was $44,319,362 and $4... [more]