Polymetallic transition metal phosphides (TMPs) exhibit quasi-metallic properties and a high electrical conductivity, making them attractive for high-performance hybrid supercapacitors (HSCs). Herein, a nanohoneycomb (NHC)-like FeNi layered double hydroxide (LDH) array was grown in situ on 3D current collector nickel foam (NF), which is also the nickel source during the hydrothermal process. By adjusting the amount of NaH2PO2, an incomplete phosphated FeNi(OH/P) nanosheet array was obtained. The optimized FeNi(OH/P) nanosheet array exhibited a high capacity up to 3.6 C cm−2 (408.3 mAh g−1) and an excellent long-term cycle performance (72.0% after 10,000 cycles), which was much better than FeNi LDH’s precursor. In addition, the hybrid supercapacitor (HSC) assembled with FeNi(OH/P) (cathode) and polypyrrole (PPy/C, anode) achieved an ultra-high energy density of 45 W h kg−1 at a power density of 581 W kg−1 and an excellent cycle stability (118.5%, 2000 cycles), indicating its great poten... [more]

In recent years, the accelerating climate change and intensifying natural disasters have called for more renewable, resilient, and reliable energy from more distributed sources to more diversified consumers, resulting in a pressing need for advanced situational awareness of modern smart distribution systems [...]

Accurate short-term wind speed forecasting plays an important role in the development of wind energy. However, the inertia of airflow means that wind speed has the properties of time variance and inertia, which pose a challenge in the task of wind speed forecasting. We employ the variable support segment method to describe these two properties. We then propose a variable support segment-based short-term wind speed forecasting model to improve wind speed forecasting accuracy. The core idea is to adaptively determine the variable support segment of the future wind speed by a self-attention mechanism. Historical wind speed series are first decomposed into several components by variational mode decomposition (VMD). Then, the future values of each component are forecast using a modified Transformer model. Finally, the forecasting values of these components are summed to obtain the future wind speed forecasting values. Wind speed data collected from a wind farm were employed to validate the... [more]

The intrusive rock buried-hill reservoir is one of the main targets for oil and gas exploration in the offshore sedimentary basins of China. In order to discover the reservoir as early as possible for decision-making to save costs, reservoir interpretation with mud-logging data needs to be studied. Previous studies have showed that the homogeneity rocks reservoir can be well interpreted with mud-logging data u the Kb (mechanical specific energy ratio) method and the WL (tangential power)-WH (vertical power) intersection method. However, reservoir interpretation with mud-logging data for intrusive rock buried-hill has not been reported. The key steps or parameters of these two kinds of methods used for reservoir interpretation need to be modified for the vertical variation of intrusive rock buried-hill. Furthermore, confirming the interpretation of these two kinds of methods has not been reported. Taking the Y area in the Qiongdongnan Basin of the South China Sea as an example, the intr... [more]

With the wide spread of new variants of coronavirus that cause the infectious disease COVID-19, governments around the world typically respond by imposing restrictions on people’s activities that range from partial to full lockdowns. This has severe implications on all economic activities, which is manifested by the changes in energy demand. In this study, the impact of COVID-19 on the electricity sector in Jordan is analysed through quantifying the strictness of the government response measures to contain the spread of the pandemic, as calculated by the stringency index, with the electricity demand by the different sectors. Results showed that the minimum peak load in 2020 decreased by 13% as compared to that of 2019. The most affected sectors were the domestic sector, whose share in consumption increased by 8%, and the commercial and hotel sector, whose share decreased by 19%. The concept of an energy-weighted stringency index was introduced to account for the impact of government re... [more]

Accurately forecasting carbon prices is key to managing associated risks in the financial market for carbon. To this end, the traditional strategy does not adequately decompose carbon prices, and the kernel extreme learning machine (KELM) with a single kernel function struggles to adapt to the nonlinearity, nonstationarity, and multiple frequencies of regional carbon prices in China. This study constructs a model, called the VMD-ICEEMDAN-RE-SSA-HKELM model, to forecast regional carbon prices in China based on the idea of ‘decomposition−reconstruction−integration’. The VMD is first used to decompose carbon prices and the ICEEMDAN is then used to decompose the residual term that contains complex information. To reduce the systematic error caused by increases in the mode components of carbon price, range entropy (RE) is used to reconstruct the results of its secondary decomposition. Following this, HKELM is optimized by the sparrow search algorithm and used to forecast each subseries of c... [more]

In order to make reasonable production-sales-stock decision-making for gasoline production enterprises, it is necessary to make an accurate prediction of the gasoline demand. However, gasoline demand is often affected by many factors, which makes it very difficult to predict. Therefore, this paper tries to construct a trend- and periodicity-trait-driven decomposition-ensemble forecasting model in terms of trend and periodicity characteristics of gasoline demand data. In order to verify the effectiveness of the proposed model, the demand data of a typical gasoline product-93# gasoline in China, is used. The empirical results show that the proposed trend- and periodicity-trait-driven decomposition-ensemble forecasting model can achieve better prediction results than the single models, indicating that the proposed methodology can be used as a feasible solution to predict the gasoline demand series with trend and periodicity traits.

The Cs/Ru/MgO catalyst was synthesized by sequential impregnation of Ru and Cs on MgO support using Ru(NO3)3 and CsNO3 precursors. Catalytic ammonia synthesis was carried out in a fixed-bed flow reactor using H2 and N2 as reactants. The stability of the catalyst was measured at 350 °C, 2.5 MPa gauge pressure, and SV as 1200 h−1 using the H2/N2 ratio 3 as a reactant feedstock. The Cs/Ru/MgO catalyst retained its ammonia synthesis activity while conducting experiments at mild reaction conditions of 325 °C and 350 °C. An increase in experimental temperature to 375−425 °C decreased the ammonia synthesis activity retaining only to 42% of the initial activity after 680 h of time on stream. The deformation of the catalyst’s structure, which was caused by Cs leaching and redistribution of the Ru and increased crystallinity of MgO at high-temperature conditions, was considered the plausible reason for the drastic decrease in ammonia synthesis activity.

The decarbonization of energy to meet the low-carbon energy strategy set for 2050 has led to a continuous increase in the contribution of electricity generated from renewables to our growing energy demands, where their inherent intermittency of supply must be addressed by a step-change in energy storage [...]

The 2010 Maule earthquake was a megathrust event that occurred along the Peru−Chile Trench. The earthquake source can be modelled as a fault with two asperities with different areas and strengths. By employing a discrete fault model, where asperities are the basic elements, the event can be described as a sequence of three dynamic modes involving simultaneous asperity slip. Interaction between asperities by mutual stress transfer plays a crucial role during fault slip. With a careful choice of values for the model parameters, the mode durations, the slip distribution, the seismic moment rate and the final moment calculated from the model are found to be consistent with the observed values. An important amount of frictional heat is produced by an event of this size and is calculated by summing up the contributions of each asperity. The seismic event produces a heat pulse propagating through the Earth’s crust and contributing to the average heat flow in the region. The calculated heat pr... [more]

The purpose of this study is to investigate the effect of free nitrous acid (FNA) and free ammonia (FA) on the anoxic phosphorus uptake rate (PUR) of polyphosphate-accumulating organisms (PAOs) via the utilization of nitrite. With this goal, upon developing a PAO-enriched culture in a sequential batch reactor, a series of batch experiments were conducted to examine the effects of nitrite and ammonium on the anoxic phosphorus uptake rate at different pH levels. According to the results, both free nitrous acid and free ammonia were found to inhibit anoxic PUR to a degree similar to their respective effects on aerobic PUR reported in previous studies, suggesting that phosphorus removal via the anoxic pathway may be just as susceptible as that via the aerobic pathway. The effect of FNA on anoxic PUR is optimally described by a non-competitive inhibition model with a KiFNA value of 1.6 μg N L−1, while the Levenspiel model with an SFA* value of 37 mg N L−1 provided the best fit for the FA ef... [more]

This paper presents original research of a model of water−water ejector whose aim is to mix a quantity of water of the return network with the water of the supply network of a central heating system. The water of the supply network at a certain pressure passes through the ejector nozzle, where the pressure energy in the nozzle is converted into kinetic energy, and consequently in the space around the nozzle vacuum gauge pressure is created which enables the absorption of a quantity of water from the network return, which is mixed with the water of the supply network. This water regulates the temperature of the water at the entrance of the central heating radiator. For the model ejector, characteristic equation was written and was analyzed in terms of pressure and mixing coefficient. The analysis was tested using nozzles of different sizes. To analyze the role of the diffuser as a part of the ejector, the ejector characteristics were analyzed without a diffuser. The characteristics of d... [more]

Heat pipes transfer heat via phase transformation of the working fluid, where the working fluid will keep the temperature constant and absorb or release a large amount of latent heat during phase transformation. With the development of heat pipe technology, the isothermal performance of heat pipes has been gradually emphasized in many application fields. Most studies focused on the average temperature characteristics of one heat pipe or several heat pipes with the same type, and lacked a comprehensive analysis on the isothermal performance of different heat pipes. In this paper, previous studies on the application fields of the isothermal performance of heat pipes, the isothermal level of heat pipes used in different fields, and the methods to improve the isothermal performance of heat pipes are summarized. The parameters of the wick have little effect on the temperature uniformity of the heat pipe, while the arrangement of the wick has more influence on the uniformity of the heat pipe... [more]

The establishment of a rock constitutive model considering microcrack propagation characteristics is an important channel to reflect the progressive damage and failure of rocks. The prepeak crack strain evolution curve of rock is divided into three stages based on the triaxial compression test results of granite and the definition of crack strain. According to the nonlinear variation characteristics of crack strain in the stage of rock crack stable propagation, rock deformation is expressed as the sum of matrix strain and crack strain. Then, the exponential constitutive relationship of rock crack stable propagation is deduced. The axial crack strains of the rock sample and its longitudinal section are equal. Thus, the longitudinal symmetry plane of the rock sample is abstracted as a model containing sliding crack structure in an elastic body, and the evolution equation of crack geometric parameters in the process of stable crack propagation is obtained. Compared with the experimental d... [more]

This Special Issue is dedicated to the XXIV Symposium on Combustion Processes (23−25 September 2019, Wrocław, Poland), which is an official symposium of the Polish Section of the Combustion Institute that takes place every two years [...]

A single watchful sleep mode (WSM) combines the features of both cyclic sleep mode (CSM) and cyclic doze mode (CDM) in a single process by periodically turning ON and OFF the optical receiver (RX) of the optical network terminal (ONT) in a symmetric manner. This results in almost the same energy savings for the ONTs as achieved by the CSM process while significantly reducing the upstream delays. However, in this study we argue that the periodic ON and OFF periods of the ONT RX is not an energy efficient approach, as it reduces the ONT Asleep (AS) state time. Instead, this study proposes an adaptive watchful sleep mode (AWSM) in which the RX ON time of ONT is minimized during ONT Watch state by choosing it according to the length of the traffic queue of the type 1 (T1) traffic class. The performance of AWSM is compared with standard WSM and CSM schemes. The investigation reveals that by minimizing the RX ON time, the AWSM scheme achieves up to 71% average energy saving per ONT at low tr... [more]

This paper discusses the authors’ experience gained with the selection of Projects of Common Interest (PCIs) in the thematic area of smart grids deployment, in the context of the TEN-E Regulation. It presents the framework for assessing candidate electricity smart grids for inclusion in the European Union list of PCIs, in view of the TEN-E Regulation and the existing literature on assessment methodologies for energy infrastructure projects. It also provides an overview of smart grid projects included in the PCI lists, with the aim to shed light on the types of projects and their contribution to accelerating the development of European cross-border energy infrastructure projects to respond to EU energy and climate targets. The paper concludes with discussion of recent regulatory initiatives and their potential implications on the presented methodology.

This paper focuses on multi-family buildings in a Swedish city district, erected between 1965 and 1973, which are now in need of renovation. For the two types of multi-family buildings in the district, tower buildings and low-rise buildings, dynamic energy use is predicted by using an energy signature method. The energy signature is then used to calculate the primary energy use number of the building stock, according to calculations methods dictated by Swedish building regulations. These regulations are also used to assess which multi-family buildings are in need of renovation, based on the buildings’ primary energy use. For buildings that need energy renovations, it is simulated so that the energy use of each multi-family building complies with these same building regulations. The proposed methodology for simulating energy renovation also determines new energy signature parameters, related to building heat loss coefficient, balance temperature and domestic hot water usage. The effects... [more]

Different solar thermal collectors have been used recently to meet the thermal requirements of single effect and double effect vapor absorption cooling systems, making selection of the correct method a challenge. Different attributes of each vapor absorption cooling and solar collector combination are taken into account, and a Multi-Attribute Decision-Making model is used to select the best option. The model requires variables indicating the performance of the system, which are called attributes that are organized into a hierarchical structure called a tree of attributes. The dependent attributes finally end up in the basic attributes representing the input to the model. The technology options considered are flat plate water heating collectors with forced circulation, flat plate air heating collectors with forced circulation, evacuated tube collectors, parabolic trough collectors, and collectors with compound parabolic concentrator. Two types of cooling, namely single effect and double... [more]

In this paper, the yields and composition of solid and condensable products that were obtained by microwave-assisted torrefaction of softwood, wheat straw, and peat fuel pellets, defined as main- and side-stream torrefaction products, were studied. The torrefaction process, at temperatures varied in the range of 200−300 °C, was performed using a laboratory-scale torrefactor of original construction. Water-enriched fractions were distilled off from condensable products to isolate tar fractions, the fuel characteristics of which were compared with those of solid fractions. Py-GC/MS/FID, GC/MS/FID, thermal analysis, elemental analysis, and wet chemistry methods were used to characterize the main- and side-stream torrefaction products, with a focus on their valorization according to the biorefinery approach. The simultaneous development of the destruction and condensation processes in lignocarbohydrate complexes during microwave treatment leads to an increase in the relative portion of aro... [more]

The COVID-19 pandemic is accelerating the rapid development of the digital economy. Previous studies have indicated that shipping fees are essential in delivery strategies and significantly impact order generation rates. According to market research, 68% of consumers would increase their orders to reach the minimum threshold for free delivery. However, previous studies have focused on the problem of setting free shipping thresholds, so the existing model of the e-commerce platform only allows consumers to choose whether to pay the total shipping fees or conditional free delivery with a free shipping threshold. A lack of literature concerns the partial pay for shipping fees before reaching the free shipping threshold. Therefore, this study proposes a new pricing model for shipping strategy that allows consumers to pay partial shipping fees. This model can increase the flexibility of consumer choice, thus increasing consumers’ willingness to purchase, which in turn increases the revenue... [more]

In the field of nuclear fusion, the power exhaust problem is still an open issue and represents one of the biggest problems for the realization of a commercial fusion power plant. According to the “European Fusion Roadmap”, a dedicated facility able to investigate possible solutions to heat exhaust is mandatory. For this purpose, the mission of the Divertor Tokamak Test (DTT) tokamak is the study of different solutions for the divertor. This paper presents the plasma scenarios for standard and alternative configurations in DTT. The Single Null scenario is described in detail. The alternative configurations are also presented, showing the good flexibility of the machine.

Precise data processing from the Global Navigation Satellite Systems (GNSS) reference station network is mainly based on a combination of double-differenced carrier phase and code observations. This approach allows most of the measurement errors to be removed or reduced and is characterized as the most accurate method. However, creating observation differences between two receivers and two satellites increases the measurement noise of the observations by a factor of 2. As a result, it increases the impact of the incorrect definition of the noise characteristic on the results of the estimation of the unknowns in the positioning model. This is especially important in Multi-GNSS solutions, which integrate measurements from different systems, for which the stochastic parameters of observation may differ significantly. In this paper, the authors prepared a complex analysis of the noise type in double-differenced GNSS (GPS, GLONASS and Galileo) observations, both carrier phase and code ones,... [more]

Block M of the Ordos Basin is a typical low-permeability tight sandstone gas accumulation. To develop these reservoirs, various horizontal well fracturing technologies, such as hydra-jet fracturing, open-hole packer multistage fracturing, and perf-and-plug multistage fracturing, have been implemented in practice, showing greatly varying performance. In this paper, six fracturing technologies adopted in Block M are reviewed in terms of principle, applicability, advantages, and disadvantages, and their field application effects are compared from the technical and economic perspectives. Furthermore, the main factors affecting the productivity of fractured horizontal wells are determined using the entropy method, the causes for the difference in application effects of the fracturing technologies are analyzed, and a comprehensive productivity impact index (CPII) in good correlation with the single-well production of fractured horizontal wells is constructed. This article provides a simple a... [more]

The accuracy of the monitoring information is particularly important for exploring fractured rock mass deformation and failure mechanisms and precursor characteristics. Appropriate monitoring methods can not only timely and effectively reflect the failure laws of fractured rock masses but also play an early warning role. To explore more reasonable monitoring methods, uniaxial compression experiments and real-time non-destructive monitoring on prefabricated fractured rock specimens through DIC, AE, and IRT were conducted; the strain field, temperature field, ringing frequency, standard deviation, etc. were analyzed; and correlation between the three methods in the information of audience was explored. The results show the following. (1) The failure evolution process of fractured rock mass can be divided into four stages. DIC can detect the initiation and propagation of cracks near the fractures of the specimen at the earliest stages. (2) The order of occurrence of precursor phenomena in... [more]