The last mile constitutes the most expensive and difficult part of the supply chain. This fact results from the density of buildings and from traffic congestion. The implemented programs that aim at increasing the effectiveness of city logistics do not always bring about the expected results, the reason being the lack of consultations with stakeholders prior to their implementation. Such consultations could help to recognize the expectations, aims and fears of each of the agent/actor groups using the urban space. The purpose of this article is to recognize the attitude of one of the groups of stakeholders (recipients/businesses located in the area) in the Polish neighboring agglomerations of Gdańsk and Gdynia, towards chosen city logistic measures. The research consisted in searching for a correlation between the attitude towards a particular city logistics measure and the size of the business, as well as between the attitude towards the given city logistics measure and the difficulty... [more]

The digital twin (DT) approach has risen in popularity for applications in many industrial process managements. By applying the “Shipyard 4.0” digital transformation trend, the ship industry is developing techniques able to reduce risks by improving operation process management. This study proposes a combination of a DT approach and practical experiment as part of a five-tier framework for DT-driven process management in the ship industry. This study focuses on the characteristic scenarios and crucial parameters within the ship engine system and shipping cargo container in operation procedures. DT-based models and platforms are established in this study based on the basic modeling of Maya and scene rendering of Unity 3D. To address the fusion issue of multi-source heterogeneous data in the ship operation process, a Bayesian neural network (BNN) method is introduced into DT’s virtual model layer and data support layer. By integrating an improved BNN-based algorithm into DT-based models,... [more]

In order to enhance the hydraulic performance of the volute pump, the Kriging model and genetic algorithm (GA) were used to optimize the 3D diffuser of the volute pump, and the hydraulic performance of the optimized model was compared and analyzed with the original model. The volute pump diffuser model was parameterized by BladeGen software. A total of 14 parameters such as the distance between the leading and trailing edges and the central axis, and the inlet and outlet vane angle were selected as design variables, and the efficiency under the design condition was taken as the optimization objective. A total of 70 sets of sample data were randomly selected in the design space to train and test the Kriging model. The optimal solution was obtained by GA. The shape and inner flow of the optimized diffuser were compared with those of the original diffuser. The research results showed that the Kriging model can effectively establish the high-precision mathematical function between the desi... [more]

A new model of particle entrapment during continuous casting of steel is presented, which includes the effects of multiphase flow from argon gas injection and thermal buoyancy from superheat in the strand. The model simulates three different capture mechanisms, including capture by solidified hooks at the meniscus, entrapment between dendrites, and engulfment by the surrounding of large particles. The fluid flow and bubble capture results are validated with plant measurements, including nail board dipping tests and ultrasonic tests, respectively, and good agreement is seen. Results suggest that the superheat has a negligible effect on the flow in the mold region. However, higher (30 K) superheat causes a more complex flow in the lower strand by creating multiple recirculation zones due to the thermal buoyancy effects. This causes less penetration deep into the strand, which leads to fewer and shallower particle captures. Lower (10 K) superheat may enable significant top surface freezin... [more]

The influence of the different properties of the gas diffusion layer (GDL) on the operation of a liquid-cooled, proton-exchange polymer electrolyte fuel cell (PEMFC) has been studied in this work. Three-dimensional numerical simulations (CFD) have been conducted to compare several commercial GDLs with different properties, analyzing their influence on the cell performance. Specifically, four GDLs (AvCarb P-75, SIGRACET 34BC, SIGRACET 34BA and Toray TGP-H-090) have been studied, two of them including a microporous layer (MPL). The effect of the MPL has been inspected by contrast of the results obtained with the same GDL, with or without MPL. Potentiostatic boundary conditions have been applied, varying the electric potential between 1.05 and 0.35 V to obtain a representative i−V curve with enough resolution. Detailed postprocessing tasks were carried out to gain a deeper understanding on the phenomena occurring within the cell for each GDL. It can be concluded from this work that a high... [more]

The color, texture and rancidity of dried fruit are critical parameters to control for consumer acceptance. The goal of this research was to investigate the kinetics of color parameter changes and texture in terms of the crispness and peroxide value (PV) of dried coconut chips by using zero-, first- and second-order kinetic reactions during storage at different temperatures, as well as shelf life prediction using the accelerated method. The outcomes demonstrated that the zero-order kinetic reaction was appropriate to describe the change in color, crispness and PV of dried coconut chips during storage (R2 = 0.9690−0.9899). The rancidity had a higher correlation than the texture and color changes used to assign the quality essence. The activation energy (Ea) for the PV change was 11.83 kJ/mol. Therefore, the shelf life expectancy of the dried coconut chips was estimated to be 144, 128 and 115 days at 35, 45 and 55 °C, respectively. Meanwhile, the shelf life of products stored at ambient... [more]

Predicting the mechanical properties of cement-based mortars is essential in understanding the life and functioning of structures. Machine learning (ML) algorithms in this regard can be especially useful in prediction scenarios. In this paper, a comprehensive comparison of nine ML algorithms, i.e., linear regression (LR), random forest regression (RFR), support vector regression (SVR), AdaBoost regression (ABR), multi-layer perceptron (MLP), gradient boosting regression (GBR), decision tree regression (DT), hist gradient boosting regression (hGBR) and XGBoost regression (XGB), is carried out. A multi-attribute decision making method called TOPSIS (technique for order of preference by similarity to ideal solution) is used to select the best ML metamodel. A large dataset on cement-based mortars consisting of 424 sample points is used. The compressive strength of cement-based mortars is predicted based on six input parameters, i.e., the age of specimen (AS), the cement grade (CG), the met... [more]

Natural convection is intensively explored, especially in a valley-shaped trapezoidal enclosure, because of its broad presence in both technical settings and nature. This study deals with a trapezoidal cavity, which is initially filled with linearly stratified air. Although the sidewalls remain adiabatic, the bottom wall is heated, and the top wall is cooled. For the stratified fluid (air), the temperature of the fluid adjacent to the top and the bottom walls is the same as that of the walls. Natural convection in the trapezoidal cavity is simulated in two dimensions using numerical simulations, by varying Rayleigh numbers (Ra) from 100 to 108 with constant Prandtl number, Pr = 0.71, and aspect ratio, A = 0.5. The numerical results demonstrate that the development of natural convection from the beginning is dependent on the Rayleigh numbers. According to numerical results, the development of transient flow within the enclosure owing to the predefined conditions for the boundary may be... [more]

To study the interactive impact and multi-agent intervention effect caused by multiple public opinion events, a SI3R interactive public opinion communication model is proposed in this paper. Based on interactive public opinion evolution and influence paths of multi-agent interventions, the dynamic equation under multi-agent intervention is formulated; the equilibrium points of the model are calculated and the stability of the model is validated; and the assignment functions are constructed. Further, real data of the case study are obtained and set as initial model simulation parameters, the multi-agent intervention and control measures are numerically simulated and the effects of comprehensive public opinion control are obtained and put forward to suggestions for public opinion management. Simulation results show that the model can simulate the interactive propagation and evolution trend of multiple public opinion events, and imitate the intervention effect of each agent. Compared with... [more]

In the steel production process in the LD converter, it is important to have information about the melt temperature. The temperature and chemical composition of the steel are important parameters in this process in terms of its completion. During the process, continuous measurement of the melt temperature and thus also information about the end of the process are missing. This paper describes three approaches to creating a mathematical model of melt temperature. The first approach is a regression model, which predicts an immeasurable melt temperature based on other directly measured process variables. The second approach to creating a mathematical model is based on the machine learning method. Simple and efficient learning algorithms characterize the machine learning methods. We used support vector regression (SVR) method and the adaptive neuro-fuzzy inference system (ANFIS) to create a mathematical model of the melt temperature. The third approach is the deterministic approach, which... [more]

The thermal environment of the development headings in deep underground mines tends to be harsh. The design of a reliable auxiliary ventilation system is an important strategy to maintain the thermal environment and air quality in the workplace. Hence, it is of great significance to comprehensively evaluate the effects of different air supply conditions and explore the optimal solution for the auxiliary ventilation system. In this study, cooling efficiency (CE) and ventilation efficiency (VE), which are the two most widely used indices for evaluating the ventilation in public places, were introduced into the field of underground mine ventilation. Numerical simulations of multiple air supply conditions were carried out to obtain the CE and VE, respectively. A data envelopment analysis model was used innovatively to evaluate and rank the efficiency of the different conditions. In the evaluation model, the air supply temperature and air supply velocity were the inputs, whereas CE and VE w... [more]

This Special Issue (SI) of Processes on Mathematical Modeling and Control of Bioprocesses (MMCB) contains papers focusing, on the one hand, on mathematical modeling of biological processes at different scales ranging from microscopic to macroscopic levels and, on the other hand, on model-based estimation, optimization and control of these processes [...]

In order to explore the influence of rotating speed on the internal flow and sealing characteristics of the liquid-sealing impeller for a liquid oxygen turbopump of a rocket engine, unsteady numerical simulations of the flow characteristics and sealing performance of the first-stage liquid-sealing impeller for a liquid oxygen turbopump under liquid phase conditions were performed. The results show that the pressurization value increases with the increase in the rotating speed. The first-stage liquid-sealing impeller, whose structure is symmetrically distributed along the center of the rotation axis, tends to be an isobaric seal at a rotating speed of 12,000 rpm, and when the rotating speed is decreased or increased, it enters the leakage state or negative pressure sealing state, respectively. The matching relationship between the rotating speed and inlet pressure has a significant effect on the pressurization value, pressurization coefficient and leakage flow rate. Under the working co... [more]

Phishing is one of the biggest crimes in the world and involves the theft of the user’s sensitive data. Usually, phishing websites target individuals’ websites, organizations, sites for cloud storage, and government websites. Most users, while surfing the internet, are unaware of phishing attacks. Many existing phishing approaches have failed in providing a useful way to the issues facing e-mails attacks. Currently, hardware-based phishing approaches are used to face software attacks. Due to the rise in these kinds of problems, the proposed work focused on a three-stage phishing series attack for precisely detecting the problems in a content-based manner as a phishing attack mechanism. There were three input values—uniform resource locators and traffic and web content based on features of a phishing attack and non-attack of phishing website technique features. To implement the proposed phishing attack mechanism, a dataset is collected from recent phishing cases. It was found that real... [more]

The success rate of automatic transplanter seedling picking is affected by the harsh operating environment of the transplanter and the reduced output accuracy of the opening and closing positioning of the seedling-picking mechanism due to the interference of the external environment. To solve such problems, the paper proposes to use an adaptive fuzzy PID control algorithm as the opening and closing positioning-control system of the seedling-picking mechanism. Based on the theoretical analysis and calculation of the positioning accuracy of the seedling-picking mechanism, a mathematical model of stepper motor angular velocity control was established, and a stepper motor angular velocity control model based on fuzzy PID (conventional PID) control was established in MATLAB/Simulink. In order to further simulate the actual working condition of the seedling-picking mechanism, a simulation model of stepper motor control with disturbance was built, and the response results showed that the fuzz... [more]

This paper proposes a possible mechanism for obtaining sizeable behavioral structures by simulating a network−agent dynamic on an evolutionary public good game with available social .learning. The model considers a population with a fixed number of players. In each round, the chosen players may contribute part of their value to a common pool. Then, each player may imitate the strategy of another player based on relative payoffs (whoever has the lower payoff adopts the strategy of the other player) and change his or her strategy using different exploratory variables. Relative payoffs are subject to incentives, including participation costs, but may also be subject to mutation, whose rate is sensitized by the network characteristics (social ties). The process discussed in this report is interesting and relevant across a broad range of disciplines that use game theory, including cultural evolutionary dynamics.

The structure and dynamics of a reciprocating pump liquid end affect the volumetric efficiency and net positive suction head. To match the kinematics with theoretical parameters, reciprocating pump valve motion and flow visualization tests and computational fluid dynamics (CFD) analyses were performed on a wing-guided bevel discharge valve in a horizontal quintuple single-acting reciprocating pump. The valve motion test results showed that the maximum pump valve displacement and the pump valve opening and closing durations were approximately 8.3 mm, 29 ms, and 38 ms, respectively. The corresponding flow visualization test results were 11.4 mm, 9.5 ms, and 35.5 ms. The valve closing durations obtained from the valve motion and flow visualization tests are approximately twice as high as the U-Adolph prediction. The maximum displacement obtained from the valve motion test is consistent with the U-Adolph prediction. Three-dimensional CFD analyses were performed to investigate the flow stat... [more]

The effect of the partition coefficient on the simulation of the operation of a biotrickling filter treating a mixture of sulfur compounds was analyzed to evaluate the pertinence of using Henry’s law in determining its removal capacity. The analysis consisted of the simulation of a biotrickling filter that bio-oxides hydrogen sulfide (H2S), dimethyl sulfide (DMS), methyl mercaptan (MM) and dimethyl disulfide (DMDS) using different types of models for determining the partition coefficient: Henry’s law for pure water, Henry’s law adjusted from experimental data, a mixed model (Extended UNIQUAC) and a semi-empirical model of two-parameters. The simulations were compared with experimental data. It was observed that Henry’s law for pure water could produce significant deviations from empirical data due to the liquid phase not being pure water. The two-parameter model better fits with similar results compared to the extended UNIQUAC model, with a lower calculation cost and necessary paramete... [more]

The relaxation of a rigid particle suspended in a one-dimensional oscillating flow is calculated according to different drag models and the results are compared. Conditions are derived under which relaxation can be neglected or drag models can be substituted by simpler ones. This investigation is conducted analytically and graphically via the plane defined by the Reynolds number and amplitude parameter. This work matches various, mostly analytic drag models together to consider simple particle relaxation with a few, broad range input parameters and cover large parts of the plane spanned by Reynolds number and amplitude parameter.

In this paper, a three-dimensional model of a high-temperature anion-exchange membrane fuel cell (HT-AEMFC) operating at 110 °C is presented. All major transport phenomena along with the electrochemical reactions that occur in the cell are modeled. Since the water is exclusively in the form of steam and there is no phase transition to deal with in the cell, the water management is greatly simplified. The cell performance under various current loads is evaluated, and the results are validated against the experimental data. The cell performance is examined across a range of operating conditions, including cell temperature, inlet flow rate, and inlet relative humidity (RH). The critical link between the local distributions of species and local current densities along the channels is identified. The distribution of reactants continuously drops in the gas flow direction along the flow channels, causing a non-uniform local current distribution that becomes more pronounced at high current loa... [more]

Pore water pressure changes due to soil-atmospheric boundary interaction can significantly influence soil behaviour and can negatively affect the safety and stability of geotechnical structures. For example, prolonged rainfall events can lead to increased pore water pressure and lower strength; repeated cycles of pore water pressure changes can lead to degradation of strength. These effects are likely to become more severe in the future due to climate change in many parts of the world. To analyse the behaviour of soil subjected to atmospheric boundary interactions, several parameters are needed, and hydraulic conductivity is one of the more important and is difficult to determine. Hydraulic conductivity deduced from laboratory tests are often different from those from the field tests, sometimes by orders of magnitude. The problem becomes even more complicated when the soil state is unsaturated, where the hydraulic conductivity varies with the soil’s state of saturation. In this paper,... [more]

As the future of transportation systems, the intelligent transportation system is a promising technology to improve the increasingly serious traffic problems. However, the integration of cyber-physical systems makes them vulnerable to new cyber−physical attacks. To ensure the security of intelligent transportation systems, a novel robust state observer-based detection and isolation method against false data injection attacks is developed. Based on the constructed dynamic model of intelligent vehicle networking, the covert characteristic of a false data injection attack is analyzed. Then, a novel state residuals-based detection criterion is developed by using a real-time observed state. To shorten the detection time, an adaptive detection threshold is designed to replace the existing computed threshold. In addition, robust state observer banks are established to isolate multiple injected attacks. Finally, simulation results on the vehicle networking system demonstrate the effectiveness... [more]

The fracturing crossing coal seam roof is a technology that fulfills the fracturing of a coal seam through the vertical propagation of fractures. Geological conditions are the key factors determining the effect of this kind of fracturing, but there is hardly any research on this aspect. To determine the favorable geological conditions for through-roof fracturing, based on a 3D fracture propagation model, and considering the interlayer vertical fracture toughness and leak-off heterogeneity, a mathematical model of fracturing through a horizontal well in a coal seam roof was established, and the calculation method of fractures crossing layer propagation was determined. In this method, the effect of fracture communication with the coal seam is evaluated by taking the area and the area ratio of fractures in the coal seam as the objective functions. The effects of parameters such as in situ stress combination profile, coal seam fracture toughness, and fluid loss coefficient on fracturing re... [more]

Fused deposition modelling (FDM) is well-known as an inexpensive and the most commonly used additive manufacturing process. In FDM, build orientation is one of the critical factors that affect the quality of the printed part. However, the activity of determining a build orientation for an FDM part, i.e., part orientation for FDM, usually relies on the knowledge and experience of domain experts. This necessitates an approach that enables the capture, representation, reasoning, and reuse of the data and knowledge in this activity. In this paper, a description logic (DL) ontology-supported part orientation approach for FDM is presented. Firstly, a set of top-level entities are created to construct a DL ontology for FDM part orientation. Then a DL ontology-supported alternative orientation generation procedure, a DL ontology-supported factor value prediction procedure, and a DL ontology-supported optimal orientation selection procedure are developed successively. After that, the applicatio... [more]

This study demonstrates the use of computational fluid dynamics (CFD) to evaluate the hydraulic properties of a new/complicated random packing structure, including flooding point, interfacial area, and liquid holdup. A standard Raschig ring and an extremely complex helical ring were employed as representative traditional and new structures. The combination of Green-Gauss node-based method with polyhedral meshing was presented to improve the hydraulic predictions. The CFD models were adopted to extend the liquid-to-gas ratio, L/G to the flooding points for hydraulic evaluation. The combination to calculate the gradient is essential for correctly evaluating the hydrodynamics of the complex helical ring. The predicted hydrodynamics for the helical ring were in good agreement with the experimental data. The helical ring has a wider operating range of L/G than the Raschig ring. Furthermore, we observed that the gas-liquid interface changed during the flooding and found that the inverted int... [more]