Unconstrained metal powders of Cu, Cr, Ni and Al were applied to submerged arc welding (SAW) to clarify the chemical behaviour of copper in this modified SAW process. Aluminium metal is avoided in SAW because it is easily oxidised. Excessive aluminium oxides in the form of slag or inclusions in the weld metal will lead to poor weld metal materials properties. Aluminium is an effective deoxidiser and can be used to prevent Cr and Ni loss to the slag by preventing oxidation of these metals. The results show that carbon steel was alloyed to 5.3% Cr, 5.3% Ni, 3.6% Al and 5.2% Cu at 80% Cr yield, 81% Ni yield, 54% Al yield and 79% Cu yield. BSE (backscattered electron) images of the three-dimensional (3D) post-weld slag sample show 3D structures within the slag dome. The 3D structures contain features of vapour formation and recondensation. In addition, nano-strands appear in the 3D structures and confirm the vaporisation and recondensation of fluorides. The chemical behaviour of copper met... [more]

The key parameters of pressure relief pre-splitting blasting technology (PRPBT) contribute to the implementation effect of goaf-side entry by roof cutting (GSERC). This study is an attempt to design the key parameters including the roof cutting height, the roof cutting angle, the spacing between blasting boreholes, the charge structure and the sealing length by using theoretical analysis, numerical simulation and field implementation. The basic quality index of the main roof is 666.27, and combined with the peeping observation result, the main roof belongs to the category of a hard main roof. Different from a weakened roof and a compound roof, the unreasonable parameters of the PRPBT for the hard main roof lead to three problems including an insufficient pre-splitting blasting effect, roof suspension in the goaf and serious damage to the rock mass for the roof cutting rib. The PRPBT effect is closely related to key parameters, including the roof cutting parameters and the pre-splitting... [more]

Hidden moving target defense (HMTD) is a proactive defense strategy that is kept hidden from attackers by changing the reactance of transmission lines to thwart false data injection (FDI) attacks. However, alert attackers with strong capabilities pose additional risks to the HMTD and thus, it is much-needed to evaluate the hiddenness of the HMTD. This paper first summarizes two existing alert attacker models, i.e., bad-data-detection-based alert attackers and data-driven alert attackers. Furthermore, this paper proposes a novel model-based alert attacker model that uses the MTD operation models to estimate the dispatched line reactance. The proposed attacker model can use the estimated line reactance to construct stealthy FDI attacks against HMTD methods that lack randomness. We propose a novel random-enabled HMTD (RHMTD) operation method, which utilizes random weights to introduce randomness and uses the derived hiddenness operation conditions as constraints. RHMTD is theoretically pr... [more]

For machine learning algorithms, fine-tuning hyperparameters is a computational challenge due to the large size of the problem space. An efficient strategy for adjusting hyperparameters can be established with the use of the greedy search and Swarm intelligence algorithms. The Random Search and Grid Search optimization techniques show promise and efficiency for this task. The small population of solutions used at the outset, and the costly goal functions used by these searches, can lead to slow convergence or execution time in some cases. In this research, we propose using the machine learning model known as Support Vector Machine and optimizing it using four distinct algorithms—the Ant Bee Colony Algorithm, the Genetic Algorithm, the Whale Optimization, and the Particle Swarm Optimization—to evaluate the computational cost of SVM after hyper-tuning. Computational complexity comparisons of these optimization algorithms were performed to determine the most effective strategies for hyper... [more]

The depletion of traditional fossil energy and the resulting environmental pollution forces people to explore new energy sources. Direct use of solar energy is now a viable solution for solving these problems. Covalent organic frameworks (COFs) are a porous crystalline material; their well-defined two-dimensional or three-dimensional frameworks can ensure the orderly arrangement of photoelectric active units, giving them potential photoelectric conversion applications. The tunable structural features endow COFs many advantages in photocatalytic hydrogen production under visible light. This review comprehensively summarizes the research progress on photoelectronic donor−acceptor (D-A) COFs with tunable structure for photocatalytic hydrogen evolution and will provide a feasible guiding strategy for applying this type of COFs in photocatalytic hydrogen production.

The aim of this research was to evaluate the influence of strawberry variety on the effectiveness of ozone application on the harvested fruit during 12 days of storage. Batches (400 g) of strawberries of the San Andreas (SA) and Camino Real (CR) varieties were stored at 10 ± 0.2 °C and exposed to gaseous ozone (0, 0.3, and 1.0 ppm) for 24 h. After the ozone exposure, the strawberries continued to be stored under refrigeration until the end of the experiment. Samples were taken daily and measurements were carried out on their physicochemical properties (weight loss, hardness, color, pH, and total soluble solids), microbiological profile (mesophilic aerobes, molds, and yeasts), bioactive compounds (total phenolic compounds and total anthocyanins), and antioxidant capacity. The obtained experimental kinetics were modeled using a first-order kinetic model. Independent of the strawberry variety, the 0.3 ppm ozone treatment generally showed the best results for most of the quality parameters... [more]

In this study, a variety of test and analysis methods, such as cast thin sections, fluorescent thin sections, scanning electron microscopy, fluid inclusions, etc., were comprehensively used and combined with logging data, sedimentary systems, burial history and other research results, to systematically study the diagenesis characteristics of Middle Permian Lower Wuerhe formation−Lower Triassic Baikouquan formation reservoirs and their control on hydrocarbon accumulation. The coupling relationship between the hydrocarbon accumulation process and reservoir secondary pores was established. The result shows that besides the development of primary intergranular pores, the reservoir develops secondary pores, such as particle dissolution pores, cement dissolution pores and fractures. The development of secondary dissolution pores, such as particle dissolution pores, carbonate and zeolite cement dissolution pores, is mainly controlled by the range and scale of organic acids produced by the the... [more]

In the context of carbon trading, energy conservation and emissions reduction are the development directions of integrated energy systems. In order to meet the development requirements of energy conservation and emissions reduction in the power grid, considering the different responses of the system in different time periods, a wind-hydrogen integrated multi-time scale energy scheduling model was established to optimize the energy-consumption scheduling problem of the system. As the scheduling model is a multiobjective nonlinear problem, the artificial fish swarm algorithm−shuffled frog leaping algorithm (AFS-SFLA) was used to solve the scheduling model to achieve system optimization. In the experimental test process, the Griewank benchmark function and the Rosenbrock function were selected to test the performance of the proposed AFS-SFL algorithm. In the Griewank environment, compared to the SFLA algorithm, the AFS-SFL algorithm was able to find a feasible solution at an early stage,... [more]

A wind−hydrogen coupled power generation system can effectively reduce the power loss caused by wind power curtailment and further improve the ability of the energy system to accommodate renewable energy. However, the feasibility and economy of deploying such a power generation system have not been validated through large-scale practical applications, and the economic comparison between regions and recommendations on construction are still lacking. In order to solve the aforementioned problems, this paper establishes an economic analysis model for the wind−hydrogen coupled power generation system and proposes a linear optimisation-based priority analysis method focusing on the major net present value for regional energy system as well as a cost priority analysis method for hydrogen production within sample power plants. The case study proves the effectiveness of the proposed analysis methods, and the potential to develop wind−hydrogen coupled power generation systems in various provinc... [more]

This work focuses on the development of a Lyapunov-based economic model predictive control (LEMPC) scheme that utilizes recurrent neural networks (RNNs) with an online update to optimize the economic benefits of switched non-linear systems subject to a prescribed switching schedule. We first develop an initial offline-learning RNN using historical operational data, and then update RNNs with real-time data to improve model prediction accuracy. The generalized error bounds for RNNs updated online with independent and identically distributed (i.i.d.) and non-i.i.d. data samples are derived, respectively. Subsequently, by incorporating online updating RNNs within LEMPC, probabilistic closed-loop stability, and economic optimality are achieved simultaneously for switched non-linear systems accounting for the RNN generalized error bound. A chemical process example with scheduled mode transitions is used to demonstrate that the closed-loop economic performance under LEMPC can be improved usin... [more]

Interlayer contradiction (high-pressure oil that prevents low-pressure oil from being extracted) has always been the main factor affecting the oil-recovery efficiency of the many oil-bearing series in shale oil wells in Eastern Shandong, China. If steps to deal with interlayer contradiction are not taken, Shengli Oilfield’s oil-recovery efficiency will be significantly reduced after a certain period of exploitation. Furthermore, as the drilling depth increases, the formation-fluid supply capacity of Shengli Oilfield becomes worse and further increases the difficulty of oil recovery as well as production costs. In order to improve the oil-recovery efficiency of shale oil wells in Eastern Shandong and realize cost reductions and efficiency increases, we designed a new jet pump in this study. The pump can be used for oil recovery according to the principle of Venturi jet propulsion, as the required power fluid is not a high-pressure fluid injected from the ground, but rather high-pressure... [more]

As a new model of networked manufacturing services, cloud manufacturing (CMfg) aims to allocate enterprise manufacturing resources, realize rational utilization of manufacturing resources, and adapt to increasingly complex user needs. However, previous studies on service composition and optimal selection (SCOS) in CMfg environments do not incorporate carbon emissions into the quality of service (QoS) evaluation indicators. Therefore, a SCOS model for CMfg under a low-carbon environment is firstly proposed in this paper. Secondly, based on the Non-dominated Sorting Genetic Algorithm (NSGA-II) algorithm, a hybrid multi-objective evolutionary algorithm, named the NSGA-II-SA algorithm, is proposed to solve the model and obtain the Pareto optimal solution set. Then, an algorithm result optimization strategy combining subjective and objective is proposed to filter the Pareto optimal solution set, so as to make the final decision. Finally, taking natural gas cylinder head production as an exa... [more]

Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) is a revolutionizing substance with vast applications in the cosmetic and food industries. Ectoine is often sourced from halobacteria. The increasing market demand for ectoine has urged the development of cost-effective and sustainable large-scale production of ectoine from microbial sources. This review describes the existing and potential microbial sources of ectoine and its derivatives, as well as microbial production and fermentation approaches for ectoine recovery. In addition, conventional methods and emerging technologies for enhanced production and recovery of ectoine from microbial fermentation with a focus on the aqueous biphasic system (ABS) are discussed. The ABS is a practically feasible approach for the integration of fermentation, cell disruption, bioconversion, and clarification of various biomolecules in a single-step operation. Nonetheless, the implementation of the ABS on an industrial-scale basis for... [more]

The optimal power flow (OPF) is an important tool for the secure and economic operation of the power system. It attracts many researchers to pay close attention. Many algorithms are used to solve the OPF problem. The decomposition-based multi-objective algorithm (MOEA/D) is one of them. However, the effectiveness of the algorithm decreases as the size of the power system increases. Therefore, an improved MOEA/D (IMOEA/D) is proposed in this paper to solve the OPF problem. The main goal of IMOEA/D is to speed up the convergence of the algorithm and increase species diversity. To achieve this goal, three improvement strategies are introduced. Firstly, the competition strategy between the barnacle optimization algorithm and differential evolution algorithm is adopted to overcome the reduced species diversity. Secondly, an adaptive mutation strategy is employed to enhance species diversity at the latter stage of iteration. Finally, the selective candidate with similarity selection is used... [more]

The pH and substrate-to-inoculum ratio (S/I) are important parameters in the anaerobic fermentation of agroindustrial residues, and therefore the optimization of these two parameters is needed for a stable, efficient, and sustainable reactor operation. In this work, the parameters pH (5−9) and S/I (0.5−3 gVS gVS−1) were optimized to produce biobased volatile fatty acids (VFAs) from hydrothermally pretreated olive mill solid waste (HPOMSW). The response variables evaluated in the Doehlert design were total VFAs concentration (tVFAs) (mg L−1) and amounts (%) of isobutyric, butyric, isovaleric, and valeric acids on the VFAs profile. The pH was the variable that most influenced the mixed culture fermentation of HPOMSW, proving to be a key parameter in the process. Microbial community analyses of conditions 1 (S/I = 3 gVS gVS−1 and pH = 7) and 4 (S/I = 1.13 gVS gVS−1 and pH = 5) showed that Proteobacteria and Firmicutes accounted for more than 87% of the total microorganisms identified for... [more]

Fungal exopolysaccharides (EPSs) represent an important group of bioactive compounds secreted by fungi. These biopolymers can be utilized individually or in combination with different bioactive substances for a broad range of pharmaceutical field applications, due to their various biological activities, such as antioxidant, antimicrobial, anti-inflammatory, antiviral, anti-diabetic, and anticoagulant effects. The paper presents an up-to-date review of the main fungal polysaccharides (pullulan, schizophyllan, scleroglucan, botryosphaeran, lentinan, grifolan, and lasiodiplodan), highlighting their structures, producing strains, and useful properties in a double position, as controlled release (rate and selectively targeting) drug carriers, but mostly as active immunomodulating and antitumor compounds in cancer therapy.

The aim of this Special Issue “Innovative Materials and Processes for Removal of Biopersistent Pollutants” (https://www [...]

Considering the complexity of the three-dimensional environment and the flexibility of the quadrotor aircraft, using the traditional A* algorithm for global path planning has the disadvantages of less search direction, more expanded nodes, and a longer planning path. Therefore, an improved A* algorithm is proposed, which is improved from two aspects. Firstly, a two-layer extended neighborhood strategy is proposed, which can increase the search direction and make better use of the flexibility of the aircraft. Secondly, the heuristic function is improved to make the heuristic function value closer to the actual planning path distance, which can reduce the expansion nodes and optimize the planning path. Finally, the path planning simulation of the improved A* algorithm is carried out and the results show that the path planned by the improved algorithm is shorter and the expanded nodes are fewer, which can guide the quadrotor to reach the destination better.

To investigate the tube thinning of gas wells in the northwestern oilfield, the failed tubing was analyzed by using material property testing, SEM, EDS, and XRD. A novel model that was specific to the service life of tubing in terms of the wall thickness of tubing was established. The model is based on the circumferential stress of tubing. The safety factor against internal pressure and corrosion rate are considered in the model. Our results make clear that the chemical composition, non-metallic inclusion, hardness, and tensile strength of the pipe meet the requirements of relevant standards. The corrosion products on the inner and outer wall of the tubing are mainly FeCO3 and BaSO4, while CaCO3 exists in the outer wall. Additionally, we prove that the corrosion process of the failed tubing is CO2 corrosion. The tubing under the packer suffers from water-accumulation corrosion, and the tubing above the packer suffers from water-carrying corrosion. It is observed that the failed tubing... [more]

The use of residual gases from steel production processes as fuel for steel treatment furnaces has attracted great interest as a method for reducing fossil fuel consumption and the steel footprint. However, these gases often have a low calorific value, and a direct substitution can lead to low temperatures or combustion instability issues. CFD simulations of the combustion of these gases can help steel producers forecast the results of the substitution before real testing and implementation. In this study, a CFD model of an industrial experimental furnace in the steel sector is developed and validated. The results are calculated using the combustion, radiation, and heat transfer models included in the software Ansys Fluent. The validation of the simulated results is performed with data acquired from experimental tests under the same simulated conditions at three air-to-fuel equivalence ratios, which vary from an excess of 0% to an excess of 5% oxygen at the outlet. The model is adjuste... [more]

With the development of Industry 4.0, artificial intelligence (AI) is gaining increasing attention for its performance in solving particularly complex problems in industrial chemistry and chemical engineering. Therefore, this review provides an overview of the application of AI techniques, in particular machine learning, in chemical design, synthesis, and process optimization over the past years. In this review, the focus is on the application of AI for structure-function relationship analysis, synthetic route planning, and automated synthesis. Finally, we discuss the challenges and future of AI in making chemical products.

This study presents a pointer-driven controller for an instrument panel. The proposed pointer utilizes the permanent magnet (PM) stepping motor produced by the Japanese company NMB. This stepping motor is vibration-proof and tolerates noise jamming as well as wind and rain exposure. Moreover, it has no mechanical structures and is low cost. Most importantly, it features accurate positioning; therefore, it can be used to measure vehicle speed, engine speed, fuel capacity, and temperature. However, the PM stepping motor of the NMB pointer requires 10 degrees for each step, and this low resolution results in roll hesitation as its steps. The aim of the current paper was to solve the problems of the large angle size and low resolution associated with this stepping motor. Based on two-phase excitation, we propose driving the motor using pulse width modulation (PWM). Specifically, we divided each 10-degree step into 100 equal parts. In other words, every step is 0.1 degrees. The resolution o... [more]

The design of new consumer chemical products is a complex task at different levels. In addition to the technical challenges of the formulation, design teams should also consider the requirements of the organization where the design is performed. The objective of this article is to present a knowledge base to support decision-making for the design of formulated products, considering the organizational dimension. For this, data were collected during ten semi-structured in-depth interviews with industrial experts who are also decisional actors in the design process. From the collected data, design recommendations were identified and analyzed. These recommendations are statements which can be used by organizations to evaluate, understand, improve, or create their own design methodologies considering their context and resources. Subsequently, the extracted recommendations were analyzed according to three types of criteria: the stages of the design process, the involved actors, and the organ... [more]

Full-scale wastewater treatment plants utilizing aerobic granular sludge technology are being built in many countries worldwide. As with all biological wastewater treatment plants, the produced waste biomass must be stabilized to protect the population, wildlife, and the environment. Digestion is usually used to break down the complex organics in the waste sludge; however, the digestibility of aerobic granular sludge still needs to be fully understood compared to the conventional activated sludge. This paper reviews the studies published on the digestibility of waste aerobic granular sludge to date. Studies comparing aerobic granular sludge and activated sludge in terms of composition, properties, and digestibility are highlighted. The impact of biological composition and physical properties on the digestibility of sludge is reviewed in terms of biomethane production and biodegradability. The effect of pre-treatment is also covered. Areas for future research are presented.

Freeze-drying is a common process to extend the shelf life of food and bioactive substances. Its main drawback is the long drying time and associated high production costs. Microwaves can be applied to significantly shorten the process. This study investigates the effects of modulating the electromagnetic field in microwave-assisted freeze-drying (MFD). Control concepts based on microwave frequency are evaluated using electromagnetic simulations. The concepts are then applied to the first part of primary drying in a laboratory-scale system with solid-state generators. Targeted frequency modulation in the electromagnetic simulations enabled an increase in energy efficiency or heating homogeneity throughout MFD while having negligible effects on the power dissipation ratio between frozen and dried product areas. The simulations predicted the qualitative effects observed in the experimental proof of concept regarding energy efficiency and drying homogeneity. Additionally, shortened drying... [more]