The residual biogas potential (RBP) test is a procedure to ensure the anaerobic digestion process performance and digestate stability. Standard protocols for RBP require a significant time for sample preparation, characterisation and testing of the rig setup followed by batch experiments of a minimum of 28 days. To reduce the experimental time to obtain the RBP result, four biogas kinetic models were evaluated for their strength of fit for biogas production data from RBP tests. It was found that the pseudo-parallel first-order model and the first-order autoregressive (AR (1)) model provide a high strength of fit and can predict the RBP result with good accuracy (absolute percentage errors < 10%) using experimental biogas production data of 15 days. Multivariate regression with decision trees (DTs) was adopted in this study to predict model parameters for the AR (1) model from substrate physicochemical parameters. The mean absolute percentage error (MAPE) of the predicted AR (1) mode... [more]

Energy systems have played an essential role in the history of human civilization [...]

Phase equilibria in the Ti-Nb-Mn ternary system at 1173K, 1273K and 1373K were studied through the equilibrated alloy method by using scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD) techniques. A new stable ternary phase K was confirmed and the composition was around Ti50Nb7Mn43. A wide-range continuous solid solution phase (Ti,Nb)Mn2 with the C14 Laves structure had been found at these temperatures due to the same phase structures of TiMn2 and NbMn2 phases. The solubility of Nb in TiMn4, αTiMn and βTiMn intermetallic compounds was determined. Based on the experimental results and reasonable extrapolations, the isothermal sections of Ti-Nb-Mn ternary system at 1173K, 1273K and 1373K were constructed.

To date, the fracture behaviour of soft, polyurethane-based adhesive joints has rarely been investigated. This work contributes to the experimental investigation of such joints in modes I and III by performing double cantilever beam (mode I) and out-of-plane loaded double cantilever beam (mode III) tests at various loading rates. The tests were evaluated using a J-integral method, which is well established for testing stiff adhesive layers and is conventionally used to determine the cohesive traction at the crack tip. Additionally, fibre-optics measurements were conducted to provide crack extension, process zone length, and cohesive traction from the measured backface strain of the adherends. It was found that the energy release rate seems to be largely independent of the loading mode. However, differences were observed regarding process zone length and resistance curve behaviour. Furthermore, the backface strain measurement allows the determination of the cohesive traction along with... [more]

With increasing climate variability, a sustainable crop production approach remains an indispensable concern across the globe. In this study, P retention/availability of MgCl2.6H2O/KOH modified Douglas fir biochar was assessed. The MgCl2·6H2O/KOH treated Douglas fir biochar was prepared by sequentially treating Douglas fir biochar with magnesium chloride and potassium hydroxide solutions. The biochar’s surface area, pore volume, morphology, and elemental compositions were determined using BET, SEM, SEM/EDS, and powder X-ray analyzes. Both surface area and pore volume were reduced by more than 97% following modification. Similarly, the morphology and elemental compositions changed after modification. The maximum P adsorbed corresponding to Langmuir−Freundlich model was 41.18 mg g−1. P sorption on biochar soil mixture was pH dependent. More studies are required to establish the field applicability of P-laden MgCl2 ·6H2O/KOH-modified Douglas fir biochar as a soil additive.

High-quality academic publishing is built on rigorous peer review [...]

Biological phenomena comprise various interactions between genes and molecules [...]

For the high-salt reservoir of the Fengcheng Formation in the Mahu area, the production decreases rapidly due to the conductivity decrease after fracturing. The analysis shows that this has a great relationship with the special salt dissolution characteristics of the High salinity reservoir. In order to study the problem of salt dissolution pattern, the effect of different temperatures, the salt concentration of fracturing fluid, the viscosity of fracturing fluid, and injection rate on the rate of salt dissolution was evaluated by using the dynamic experimental evaluation method of salt dissolution. Through the grey correlation analysis of salt rock dissolution rate, it can be found that the degree of influence is from large to small which the influence of temperature is greater than fracturing fluid velocity, followed by fracturing fluid viscosity and, finally, fracturing fluid salt concentration. The results of compressive strength tests on salt-bearing rocks after dissolution show t... [more]

Specific parameters of cake filtration, such as the filter cake and filter medium resistances, can be determined using the pressurized housing cell standardized in the guideline VDI 2762 by measuring the filtrate mass on a laboratory scale. For reproducible measurements and an exact detection of the filtration start, an improved test setup is presented and compared with a standard setup according to the guideline VDI 2762. On the basis of measurements without and with a particle system to be filtered, it is shown that the characteristic nonlinear course at the beginning of each filtration, which can be seen in the t/V-V diagram, is influenced by the used measuring equipment.

With the further exploitation of offshore resources, there are more and more offshore oil and gas fields which cannot meet the production capacity requirements. So, it becomes extremely urgent to pay attention to the decommissioning of the exploitation equipment in abandoned offshore fields. A new decommissioning solution is offered by the double-ship integrated offshore platform decommissioning equipment comes. However, as the equipment will inevitably bear the combined actions of various dynamic and static loads during operation, the strength and stability of the overall unit and the connections between different modules will be greatly challenged by the complex ocean. Firstly, the dynamic characteristics of the integrated decommissioning system are analyzed in this paper. Mathematical modeling of the lifting arm system is established based on the unit characteristics matrix, and a dynamic equation of the flexible lifting arm unit and system is developed based on Lagrange’s equation... [more]

This study introduces a Vorticity Index (VI) and an Imminent Vortex Separation Condition (IVSC), which are considered valuable indicators to quantify the vorticity impact on vertical axis wind turbines (VAWTs) operation. The VI and IVSC are specifically applied to a H-Darrieus vertical axis wind turbine (VAWT). Findings show that these two parameters display a direct relationship with the aerodynamic forces that govern the performance of this type of VAWT. This analysis is accomplished via 2D-CFD simulations of a H-Darrieus with a symmetrical NACA 0018, powered by high winds (8 and 20 m/s), by using a Shear Stress Transport SST k-ω model. The 2D model used is validated for Class II winds (8 m/s), for tip speed ratios (λ) ranging from 0.4 to 0.9. Power coefficients (Cp) predictions are close to those obtained with both 3D simulations and with experimental data, reported in the technical literature. It is found with the numerical simulations developed, that despite the significant increa... [more]

Colleges and universities are a typical service water consumers in China, i.e., with a dense population, single structure, and regular water use. This means it is crucial to strengthen the management of their water use behavior. In this paper, first of all, the main water devices and water use behavior of students were elucidated by investigating and analyzing the structure and scenarios of water use in colleges and universities. Then, a model of water use behavior of college students with sociodemographic and environmental characteristics was constructed based on the theory of planned behavior (TPB). By investigating and analyzing the water use behavior, the theoretical judgment of the improved TPB model that “behavior is the result of interaction between individual and environmental characteristics” was proved, which provides a reference for studying the water demand requirements of college students and supports scientific water-use management in colleges, our results also help the e... [more]

We report the design, fabrication, and testing of a humidity sensor based on an optical fiber-based evanescent wave probe. The fiber was bent into a U-shape and de-cladded at the location of the bending. The de-cladded section was coated either with Au or with ZnO nanoparticles. Humidity is detected based on the interaction in the surface plasmon resonance of the Au/ZnO nanoparticles excited by an evanescent wave of light passing through the optical fiber. The response of the U-bent fibers to humidity was investigated using a specifically designed low-voltage portable interrogation box. We found that the fibers coated with ZnO nanoparticles were able to detect a minimum 0.1% change in humidity with an average sensitivity of 143 µV/%RH and 95% linearity over the 10% to 80% humidity range. In comparison, samples coated with Au and Au + ZnO nanoparticles demonstrated a minimum change detection of 0.3% RH and 2% RH respectively. The response and recovery time of the sensor were measured to... [more]

AF1410 is a low carbon high alloy ultra-high strength steel. It not only has high strength and high toughness, but also has a high stress corrosion resistance. However, due to the characteristics of hard quality and poor thermal conductivity, AF1410 is a difficult material to process. In the process of milling, the geometric factors of process parameters, the flexible deformation of milling cutter and the flutter of the process system all affect the surface roughness, which makes it difficult to predict the surface roughness of milling parts. In order to solve this problem, a prediction model for surface topography of ultrahigh strength steel AF1410 was studied. To solve this problem, this paper studies the formation of milling surface topography, considers the dynamic displacement of the milling system, proposes a modeling method of surface topography based on the dynamic characteristics of the milling system and forms a prediction model. On this basis, the surface topography of ultra... [more]

Furfural is one of the most important biomass platform compounds and can be used to prepare various high-value-added chemicals. The reactions of furfural with aliphatic alcohols via an oxidative esterification reaction or oxidative condensation reaction can bond two carbon molecules together and produce longer hydrocarbon chains chemicals, including methylfuroate and some low-volatility liquid biomass fuels. Thus, these reactions are considered significant utilization routes of furfural, and many inspiring catalytic systems have been designed to promoted these reactions. In this work, the reported catalytic systems for the oxidative esterification and oxidative condensation reactions are reviewed separately. The catalysts for the oxidative esterification reaction are reviewed for the classification of noble metal catalysts and non-noble metal catalysts, according to the active metals in the catalysts. For the oxidative condensation reactions, the studies using oxygen as the oxidant are... [more]

Parametric design, with its unique scientific and logical nature, is gradually applied in the field of landscape design. Therefore, the GIS (geographic information systems) technology of parametric software was applied to the optimization of traditional landscape architecture, and its practical application quality was discussed. The actual analysis results showed that the evaluation result of parametric design had the highest score of 7.71 in behavioral perception. The overall score was 7.28, showing a high scientific nature. In the evaluation of landscape environmental benefits, after the optimization of landscape greening by parametric design, the air cleanliness and living comfort were generally improved, compared with those before optimization, and the highest values were 11.97 ± 6.01 and 5.86 ± 2.11 respectively. In the evaluation of the economic benefits of gardens, the economic income of gardens in the past 8 years generally increased, reaching the highest of 3.5795 billion yuan... [more]

Anthracite in a specific area of Shanxi Province is the subject of this essay’s research. In the creep studies, different porosity intervals and pore water pressures were employed to evaluate the mechanical properties of creep under various test paths. The conventional Burges model was coupled in series with the nonlinear viscous elements and plastic elements. The key parameters in the equation are fitted, and a creep model is created to describe the nonlinear viscosity-elastic-plastic characteristics of coal under the influence of pore water pressure with varying porosities. The creep tests used varied porosity intervals, pore water pressures, and test paths to study the mechanical properties of creep. The conventional Burges model was coupled in series with the nonlinear viscous element and plastic element. To represent the nonlinear viscosity-elastic-plastic properties of coal under the effect of pore water pressure with variable porosities, the main parameters in the equation are f... [more]

The goal of this study was to evaluate the impact of simulating different fuel shapes for the material testing reactor (MTR). Two OpenMC codes were built, and the first OpenMC model was simulated using a curved shape fuel element to mimic the real dimensions and shape of the MTR. The code core parameters were validated with the collected parameters from the experimental work and two well-known Monte Carlo simulation codes (MCNP and SCALE). The validation process included the axial flux profile and criticality. After the OpenMC curve fuel model was validated, the MTR fuel was simulated as flat fuel elements with the exact amount of fuel as in the curve fuel model. By comparing the two OpenMC models’ calculations, it was observed that the radial flux distribution has only a slight difference due to fuel mass similarity. In conclusion, simulating the MTR fuel as flat elements provided a good agreement calculation compared to the real shape, but it was also observed that this might carry s... [more]

The purification of molten salts from admixtures as well as the effective control of admixture concentration has attracted researchers’ interests. In the present paper, the possibility of the electrochemical purification of PbCl2 from PbO and the effective control over the oxide ions concentration in molten PbCl2 is studied at the temperature of 520 °C. The PbCl2 melt with the initial addition of 0.5 wt% of PbO was used as a molten salt sample. The method of potentiostatic electrolysis was used to remove the oxide additions from the melt; the linear and square-wave voltammetry dependencies were recorded, and the melt samples were taken for analysis. Based both on the results of the electrochemical measurements and the analysis of oxygen concentration in the electrolyte, we built linear empirical dependencies of the anode peak current of the oxidation of oxygen-containing electroactive anions on the PbO concentration in the studied melt. We demonstrated that the obtained dependencies ma... [more]

Information and communication technology (ICT) companies strive for ceaseless innovation to remain competitive while facing the challenge of maximizing firm value (FV) with limited resources, and increasing the interests of shareholders. However, capital structures have a considerable effect on FV, and the literature still disagrees with the optimum structure in specific industries and countries. Therefore, this study evaluates the FV of ICT companies in terms of profitability efficiency using data envelopment analysis. In addition, this study applies a Tobit regression and Kruskal-Wallis one-way ANOVA to identify the impact of leverage, liquidity, and firm size, which are major capital structure factors influencing FV. The analysis yields three main results. First, in the ICT industry, small and medium companies tend to have better profitability efficiency than companies of other sizes. Second, only small and medium ICT manufacturing companies’ profitability efficiency is positively i... [more]

The P-S-N curve is a vital tool for dealing with fatigue life analysis, and its fitting under the condition of small samples is always concerned. In the view that the three parameters of the P-S-N curve equation can better describe the relationship between stress and fatigue life in the middle- and long-life range, this paper proposes an improved maximum likelihood method (IMLM). The backward statistical inference method (BSIM) recently proposed has been proven to be a good solution to the two-parameter P-S-N curve fitting problem under the condition of small samples. Because of the addition of an unknown parameter, the problem exists in the search for the optimal solution to the three-parameter P-S-N curve fitting. Considering that the maximum likelihood estimation is a commonly used P-S-N curve fitting method, and the rationality of its search for the optimal solution is better than that of BSIM, a new method combining BSIM and the maximum likelihood estimation is proposed. In additi... [more]

Fungi of the Monascus species are used in Asia for the production of fermented foods, mainly due to the ability of these fungi to produce secondary metabolites such as pigments. Due to the growing discussion about the use of synthetic dyes and the fact that their ingestion is associated with harm to human health, studies have sought to replace these dyes using natural pigments, and new alternatives for the production of these natural pigments have been presented. In this context, Monascus pigments are a viable alternative for application in the food industry. This study aimed to evaluate different main carbon sources and pH conditions in the red pigment production of Monascus sp. We found that mannitol, when used as the only carbon source, stimulated the production of extracellular red pigment, reaching a concentration of 8.36 AU in 48 h, while glucose and sucrose reached concentrations of 1.08 and 1.34 AU, respectively. Cultivation in a bioreactor using mannitol showed great potential... [more]

Very high viscosity significantly impacts the mobility of heavy crude oil representing difficulties in production and a decrease in the well’s efficiency. Downhole electric heating delivers a uniform injection of heat to the fluid and reservoir, resulting in a substantial decrease in dynamic viscosity due to its exponential relationship with temperature and a drop in frictional losses between the production zone and the pump intake. Therefore, this study predicts temperature and viscosity profiles in heavy oil-production wells implementing a downhole induction heater employing a simplified CFD model. For the development of the research, the geometry model was generated in CAD software based on the geometry provided by the BCPGroup and simulated in specialized CFD software. The model confirmed a 46.1% effective decrease of mean 12° API heavy-oil dynamic viscosity compared with simulation results without heating. The developed model was validated with experimental data provided by the BC... [more]

Currently, the integration method of silicon PIN radiation detectors faces challenges such as complex processes, poor reliability and thick dead layers. Novel integration methods based on metal bonding technology for realizing the integration of thick and thin PIN detectors are needed with the requirement of reducing signal crosstalk, package volume and weight. Combined with the current research on metal bonding technology, this paper presents an extensive review of metal bonding technology, especially metal Al bonding technology, to provide a certain reference to future research on the bonding processing of high-performance silicon PIN detector devices.

In the context of sustainability, viticulture will address issues related to soil fertility in the coming period. Greater attention will therefore be paid to replacing traditional manure-based fertilisers, such as farmyard manure, with new types of fertiliser in the form of composts, digestate, etc. Experience to date suggests that good-quality composts are not only a source of nutrients that the vines take from the soil each year, but also a source of organic matter. The application of compost and its subsequent decomposition in the soil profile can have a positive effect on the growth of the roots and above-ground parts of the vine. However, optimising the effects and action of compost is linked to determining the necessary doses and methods of application. The aim of this three-year study was to provide an overview of the results aimed at evaluating the effects of the application of compost (CO) and compost enriched with the addition of lignohumate (CO+L20), at a rate of 30 t·ha−1,... [more]