Dynamic Process Model Research Articles

Dynamic analysis of towed cable with variable length during turning maneuvers

The configuration of marine towing cable changes significantly during the turning process, with the rotating procedure with fixed cable length being the most frequent. To overcome these challenges, the configuration and dynamic properties of the marine towing cable must be addressed. However, under some particular operating situations, the tugboat must release the marine towed cable during rotation, resulting in a constant change in the length of the marine cable. In view of this, the towed cable is discretized into a lumped mass model based on the lumped mass method, and the dynamic analysis model of the rotation process of towed cable with variable length under different release speeds and different depths is established. This is done with reference to the specific parameters of a towed system, combined with the specific sea conditions of a particular sea area. Time-domain coupling analysis is used to determine the dynamic changes in configuration and stress of marine towing cable at various release speeds and depths. The results of the calculations have some guiding relevance for a certain engineering practice.

Study on concentration distribution and detonation characteristics for non-axisymmetric fuel dispersal

The study of non-axisymmetric fuel dispersal and detonation can provide reference for the prevention of industrial cloud explosion accidents and the design of fuel air explosive (FAE). The concentration and detonation fields of 85 kg cylindrical and fan-shaped fuel are investigated by experiments and numerical simulations. A dynamic model of the whole process for fuel dispersal and detonation is built. The concentration distribution of fuel is used as the initial condition to calculate the detonation stage, thus solving the initial value problem of detonation field. The phase and component changes of fuel cloud at different locations are compared. The fuel cloud is divided into directions of 0°, 90°, 135° and 180°. The results show that the maximum cloud radius is 20.94 m in 135° and the minimum is 12.04 m in 0°. The diameter of the detonation fireball is 53.6 m, and the peak temperature is 3455 K. The highest peak overpressure is 3.44 MPa in 0° and the lowest is 2.97 MPa in 135°. The proportion of liquid phase in 0° is 22.90%, and the fuel loss is 11.8% and 9% higher than that in 135° and cylindrical charge, respectively. The stable propagation distance of blast wave in 135° is 42.50% longer than 0° and 28.37% longer than cylindrical charge.

Adjustment of the axial load on the bit when hole deepening by using the screw mechanism

The object of the research is a screw mechanism for adjusting the axial load on the bit during a hole deepening. Mathematical modeling of dynamic processes that occur in the drill string during the hole deepening in deep wells is considered. It is shown that in the process of hole deepening, the longitudinal oscillations are proportional in their intensity to the torsional ones. Obtained boundary conditions for mathematical models of the column with the use of a shock absorber or a screw amplifier. In the course of research, it was found that the screw working mechanism of the axial load creates a relationship between the axial load on the bit and the torque on the screw. This makes it possible to install safety devices that limit the torque of the drive shaft (reciprocating engine, rotor). It is shown that various types of energy supplied to the punch, which are transformed by the punching motor and amplified due to the axial (screw) amplifier installed above the bit, ensure the rotary-progressive movement of the ball bit and increase the drilling performance. It was determined that the obtained dependencies take into account the change in time of the axial load and torque depending on the parameters of the axial amplifier and the geological and technical conditions of drilling and the arrangement of the bottom of the drill string. The research results will be useful to scientists and specialists of the oil and gas industry during the physical modeling of the processes of adjusting the axial load on the bit during a hole deepening by using a screw mechanism.

Dynamic modelling and simulation of industrial scale multistage flash desalination process

Multistage Flash (MSF) desalination process is still a dominant process, especially in the Gulf region, to produce high quality freshwater. Although there has been energy price surge in recent years, MSF process will continue to operate in that region for some foreseeable future. The key challenge is how to make such processes still profitable. Understanding the dynamics of any processes under uncertainty and disturbances is very important to make a process operationally feasible and profitable. The main aim of this work is to understand the dynamics of industrial scale MSF process using high fidelity and reliable process model. For this purpose, a detailed dynamic model for the MSF process incorporating key and new features is developed and validated against the actual data of a large-scale seawater desalination plant. The model is then used to study the behaviour of large scale MSF processes for disturbances in steam temperature, feed temperature and the recycle brine flow rate. The simulation results show that the last stage requires a longer time to settle compared to the preceding stages. In addition, steam temperature shows insignificant influence on the performance ratio compared to the inlet seawater temperature and recycle brine flow rate. Furthermore, it is found that the productivity of plant can increase in the winter compared to that in the summer. However, this benefit comes at the expense of increased steam consumption in the winter, resulting in a low performance ratio.

Modeling and Control Design for Distillation Columns Based on the Equilibrium Theory

Distillation columns represent the most widely used separation equipment in the petrochemical industry. It is usually difficult to apply the traditional mechanism modeling method to online optimization and control because of its complex structure, and common simplified models produce obvious errors. Therefore, we analyze the mass transfer process of gas-liquid fluid on each column tray based on the theory of gas-liquid equilibrium and establish a nonlinear dynamic model of the distillation process. The proposed model can accurately characterize the nonlinear characteristics of the distillation process, and the model structure is largely simplified compared with the traditional mechanism model. Therefore, the model provides a new approach for model-based methods in distillation columns, especially for cases that require efficient online models. Two case studies of benzene-toluene distillation systems show that the nonlinear model has high concentration observation accuracy. Finally, a generic model control scheme is designed based on this model. Simulation results show that this control strategy performs better than a traditional PID control scheme.

Rigorous dynamic simulation methodology for scenario-based safety analysis of pressure-swing distillation considering independent protections

Process engineers often assess process safety performance early in the design stage to reduce or eliminate potential hazards cost-effectively. Process simulation tools widely used in design can provide fast and precise hazard evaluation using limited design information. However, there is a knowledge gap on how to build rigorous dynamic process models and how model configurations can affect safety analysis results. This study applied commercial dynamic simulation software, Aspen Dynamics, to address these issues through rigorous dynamic simulations and safety analysis of a two-column pressure-swing distillation with top recycling. The study implements and simulates various layers of protection, including basic process controls, alarms, safety instrumented systems, and pressure relief systems, and evaluates their impact on accident prevention. The hazardous scenarios considered are overpressure and flooding in the distillation columns, and the dynamic responses to a set of deviations such as coolant and steam utility failures and undesired throughput and composition disturbances are investigated. A scenario-based safety analysis is performed to assess the dynamic safety performance and the effectiveness of protection layers. The results indicate that the presented scenario-based dynamic safety analysis methodology is essential for accurately determining dynamic column behaviors, thereby better assisting in determining process safety time and designing effective safety systems.

Dynamic Occlusion Modeling and Clearance Control of the Visual Field of Curved Highway Roadside Landscape

In order to solve the control of the degree of anti-occlusion of the roadside landscape of the expressway curve according to the drivers’ visual characteristics during high-speed driving, a dynamic space model of the visual process of curved highway roadside landscape was established, and the calculation equation of roadside landscape visual field was derived. The dynamic occlusion ratio was defined by space coordinates, and the judgment model was proposed for the de-occlusion of the roadside landscape visual field. According to the standard design parameters of the G4 Highway Hunan section, the occlusion laws were analyzed by MATLAB for different widths and different heights of obstructions as well as the same widths and heights of obstructions at different positions in the roadside landscape visual field, thus the control value and control content of anti-occlusion clearance for the roadside landscapes were proposed. The results show that the anti-occlusion clearance control range of the roadside landscape is 270 m at the design speed of 120 km/h, 220 m at 100 km/h, and 170 m at 80 km/h. The control value of clearance width is 25 m, and the control value of clearance height is recommended to be 20 m. Within the scope of highway land expropriation, it is recommended to land expropriation 25 m wide from the road boundary. The research provides model support for building the closeness and openness of highway roadside landscape.

Analytical Design of the Regulator for Ensuring the Optimality and Stability of the Reserve of Innovative Industrial Products

Demanded by the formation of the knowledge economy and the digitalization of its industrial sphere, the development of science-intensive industries requires the analytical design of the regulator and economic and mathematical modeling of dynamic processes of saturation of the market segment with innovative industrial products. In this context, two tasks are being formalized: the first is the regulation of the reserve of these products in order to stabilize it in conjunction with the indicators of the rate of change in the volume of its production and demand for it, and the second is the analytical design of the optimal regulator of the reserve of innovative products with the achievement of a minimum of its content and losses arising from due to the shortage of this product with an increased demand for it, with the proof of the asymptotic stability in general of the obtained solutions of both problems. The construction of corresponding models deepens the understanding of investment and innovation processes and equips analytical tools for adaptive management of the efficiency and stability of industrial enterprises in a turbulent economic environment.

Robust Control Based on Adaptive Neural Network for the Process of Steady Formation of Continuous Contact Force in Unmanned Aerial Manipulator

Contact force control for Unmanned Aerial Manipulators (UAMs) is a challenging issue today. This paper designs a new method to stabilize the UAM system during the formation of contact force with the target. Firstly, the dynamic model of the contact process between the UAM and the target is derived. Then, a non-singular global fast terminal sliding mode controller (NGFTSMC) is proposed to guarantee that the contact process is completed within a finite time. Moreover, to compensate for system uncertainties and external disturbances, the equivalent part of the controller is estimated by an adaptive radial basis function neural network (RBFNN). Finally, the Lyapunov theory is applied to validate the global stability of the closed-loop system and derive the adaptive law for the neural network weight matrix online updating. Simulation and experimental results demonstrate that the proposed method can stably form a continuous contact force and reduce the chattering with good robustness.

A probabilistic, flux-conservative particle-based framework for transport in fractured porous media

Advection dominated transport processes in sub-surface formations are characterized by discontinuities in the fields of transported quantities, and realistic predictions are challenging for Eulerian transport schemes because they suffer from numerical diffusion. Henceforth, we have focused on developing a Lagrangian particle-tracking scheme for modeling advective solute transport in fractured media. To this end, we adopt an Embedded Discrete Fracture Model (EDFM) for fractured media with a permeable matrix. The flexibility to use non-conformal fracture–matrix discretizations makes EDFMs a compelling choice in field-scale flow problems. Unaffected by the numerical diffusion, Lagrangian transport schemes complement the potential of EDFMs by allowing the use of sufficiently large grid cell sizes for flow field computations.In an EDFM framework, the inter-continuum fluid mass exchange cannot be quantified by the particle trajectories/pathlines due to the unresolved fracture–matrix interfaces and different dimensionalities of the matrix and fracture discretizations. These constraints motivate the use of a stochastic particle-tracking scheme, and thus, we formulated a pathline-specific probability of inter-continuum particle transfer based on mass conservation of an elementary solute/fluid mass. The particle’s transfer probability is calculated for the maximum residence time period in its associated fracture/matrix control volume, thus making the scheme time-adaptive. In addition, a conditional residence time distribution was derived, which dictates the timestamp of the particle transfer.First, we showcase that the tracking scheme preserves the initially homogeneous solute concentration field, suggesting that the probabilistic rules are consistent with the inter-continuum fluxes. Additionally, we illustrate the estimation of an evolving solute plume and compare the results with those of an Eulerian counterpart. The presented stochastic approach enables straightforward formulations of Lagrangian models for dynamic and sub-grid processes, e.g., solute interactions with the solid phase, the mapping of their effects onto large scale transport and additionally, be included in random walk models for dispersion.

Fuzzy Algorithmic Modeling of Economics and Innovation Process Dynamics Based on Preliminary Component Allocation by Singular Spectrum Analysis Method

In this article, the authors propose an algorithmic approach to building a model of the dynamics of economic and, in particular, innovation processes. The approach under consideration is based on a complex algorithm that includes (1) decomposition of the time series into components using singular spectrum analysis; (2) recognition of the optimal component model based on fuzzy rules, and (3) creation of statistical models of individual components with their combination. It is shown that this approach corresponds to the high uncertainty characteristic of the tasks of the dynamics of innovation processes. The proposed algorithm makes it possible to create effective models that can be used both for analysis and for predicting the future states of the processes under study. The advantage of this algorithm is the possibility to expand the base of rules and components used for modeling. This is an important condition for improving the algorithm and its applicability for solving a wide range of problems.

Adaptation process of a culturally congruent parenting intervention for parents of Hispanic adolescents to an online synchronous format.

Adaptations to interventions for specific settings or communities are critical for facilitating successful implementation. The Dynamic Adaptation Process model was applied to systematically assess the adaptation process made to an in-person parenting intervention (FPNG+) prior to its implementation online. This qualitative case study design included meeting notes and interviews completed with project team members. Meeting notes were analyzed using content analysis. Semi-structured interviews regarding project team members' roles on FPNG+ and processes and activities they identified as critical for the adaptation of FPNG+ to an online intervention were analyzed using a deductive-inductive approach. In the formative phase, three primary processes were identified: information gathering to determine if the environment existed for the implementation of an online program; considerations to support the facilitation process of FPNG+ to an online environment, and decision-making to support modifications to FPNG+. The pre-implementation phase consisted of three processes: information shared by the instructional designer to facilitate the delivery of the FPNG+ content online; modifications made to the format of the intervention to meet the cultural needs of Hispanic families and address contextual issues; and iterative efforts to tailor the intervention by the project team. This study used implementation science to distinguish the dynamic processes that occurred across different systems and multiple levels in the project team's effort to modify FPNG+ to an online intervention. The contribution of this study underscores the importance of identifying the processes that facilitate the modifications made to an intervention and the capacity to implement the modified intervention with Hispanic families.

ТЕОРЕТИЧНІ ДОСЛІДЖЕННЯ ВИЗНАЧЕННЯ КРИТИЧНИХ УМОВ МІКРОКЛІМАТУ ПРИ АВАРІЙНИХ ВІДКЛЮЧЕННЯХ ТЕПЛОПОСТАЧАННЯ З УРАХУВАННЯМ КОНСТРУКТИВНИХ ОСОБЛИВОСТЕЙ БУДИНКІВ

Purpose. Analysis and research of determining critical microclimate conditions in emergency situations in heat supply systems, taking into account external climatic conditions and structural features of buildings, which are caused by the acceleration and cheapening of construction processes thanks to the introduction of the latest technologies. Methodology. Theoretical and experimental research based on fundamental knowledge in the field of thermal processes and methods of solving heat exchange problems, modelling of dynamic processes, methods and analysis of random processes, methods of mathematical statistics and forecasting. Results. On the basis of the conducted research, the regularities of the influence of the environment on the maintenance of the microclimate conditions of the premises, depending on the structural features of buildings and structures in emergency situations in heat supply systems, have been established. The limit conditions for achieving critical conditions of the microclimate of premises as a result of accidents in heat supply systems have been determined, which makes it possible to predict the limit conditions for eliminating the consequences of emergency situations and to optimize the activities of repair and rescue services, which are especially relevant in connection with the failure of outdated heat supply systems and combat operations on territory of the country. Scientific novelty. Determining the patterns of environmental influence on the maintenance of indoor microclimate conditions in connection with the structural features of buildings and structures in emergency situations in heat supply systems, which allows controlling the heat supply mode to ensure certain indoor microclimate conditions. Practical significance. Improving the forecasting of the limit conditions for liquidation of the consequences of emergency situations in heat supply systems allows optimizing the activities of repair and rescue services, especially in connection with the failure of outdated heat supply systems and combat operations on the territory of the country.

Robust Dynamic Latent Variable Model for Dynamic Process Monitoring With Missing Data in Cyber-Physical Systems

Robust Dynamic Latent Variable Model for Dynamic Process Monitoring With Missing Data in Cyber-Physical Systems

THE PROBLEM OF MINIMIZING DISPERSION

The work is related to the problem of finding the probability density of a continuous random variable in such a way that the variance or initial moments of this variable would be the smallest. The problem of minimizing the variance is solved under the condition that the probability density u x of a continuous random variable does not exceed a given function q x . The result of the work is obtaining such a density: it should be equal to the given function q x in some interval , , outside this interval the density should be zero. The numbers α and β are find from the system of nonlinear equations and are included in these equations as limits of definite integrals. By substituting the found function in the extreme condition, the smallest variance value for any continuous random variable is obtained. The problem of finding the probability density of a random variable is also considered under the conditions x u x dx u x dx u x q k              min, 1, 0 , where q and k are given positive numbers. The described problems belong to the class of Lyapunov extremal problems containing integrals. When solving them, the minimum principle and the method of Lagrange multipliers were applied. As a consequence of the Weierstrass theorem, it follows that the found stationary points are the points of the smallest values of the considered functionals. Substituting the solution of the problem into an extreme condition, an inequality for the initial moments of any continuous random variable, which is bounded from above by a positive constant q is obtained. It is emphasized that the determination of parameters as a result of minimization will allow to determine more accurate estimates in other values and to achieve an effective level of parameter optimization. The results of solving mathematical problems are given. An exemplary application of the given problem is the implementation of adaptive forecasting and statistical identification of nonlinear dynamic models of physical and economic processes. The scientific novelty of the obtained solution lies in the fact that, for the first time, a system was obtained in which the mathematical expectation of an extreme random variable is located in the middle of the segment , , due to which, by substituting the found function in an extreme condition, the smallest variance value for any continuous random variable is obtained.

Verification of modeling of dynamic processes in the port structures area

Verification of modeling of dynamic processes in the port structures area

The mechanism of degradation polycyclic aromatic hydrocarbons by magnetic biogenic manganese oxides

This study describes the degradation of α-naphthol by magnetic biogenic manganese oxides (M-BMnOx) prepared using Pseudomonas putida strain QSY-1 and magnetic nanoparticles (MNPs) added to the medium. The influence of various reaction parameters, such as pH, temperature, and initial α-naphthol concentration, was systematically investigated. Based on a complete process dynamics model and the initial kinetic analysis, the degradation rate of M-BMnOx was shown to be faster than that of biogenic manganese oxides (BMnOx). The α-naphthol removal rate during the recycling of M-BMnOx also reached 100 % within the fourth cycle. The reaction pathway of α-naphthol was determined. Analyses of the α-naphthol degradation solution showed that M-BMnOx have superior removal efficiency compared with that of BMnOx, which makes it a potentially reliable technique for degrading high concentrations of α-naphthol wastewater.

Математична динамічна модель теплових та гідравлічних процесів в баках паливної системи літака

A generalized mathematical model of dynamic thermal processes in fuel system tanks and hydraulic processes in the supercharging and drainage system is proposed. In the model of dynamic temperature changes in the CB, the idea of forming a parametric dependence is laid down, which, due to the selection of the values of the model parameters, would take into account the influence of the main factors at different stages of the flight and allow the adjustment of the model. 9 such parameters are highlighted and illustrated how each of them separately affects the temperature change in the tank. The given calculation data show that the change in their values has a different effect on the shape of the graph of the temperature change in the CB for the analyzed flight. Therefore, due to their selection, it is possible to obtain temperature values in the CB close to the experimental ones. The found values of the coefficients change little for different variants of flights, which indicates the acceptability of model (4) - (6) for use in preliminary analysis for a number of flights based on one of them. Such a model, perhaps in a somewhat simplified form, can be used in assessing the flammability of fuel in aircraft tanks. For the model of hydraulic processes, a universal algorithm for determining the flow distribution for 10 variants of boundary conditions for the network is proposed, which describes the calculation scheme of the supercharging and drainage system, where part of the boundary conditions can be set implicitly, provided that the pressure drops on the branches of the network are linear functions of the flow rate in the corresponding branch. This model complements the general model of dynamic hydraulic processes in the supercharging and drainage system, including tanks, which was proposed by the author earlier.

Modeling and Control Strategies of an Intensified System (Microreactor) with Time Delay Compensation

AbstractA theoretical process model was developed for microreactors where the conservation of mass and energy balance is treated as plug‐flow reactor to study the control strategies and closed‐loop performance of an intensified system. The resulting second‐order plus time delay and numerator dynamic process model produced a high order of controller formulation, i.e., a proportional‐integral‐derivative‐derivative‐derivative (PID3). Lower time delay and smaller closed‐loop time constant yield a better set‐point tracking and disturbance rejection. Classical PID controllers could also be achieved by truncating the high‐order term in the higher‐order dominant system of controller formulation into the desired form whilst maintaining its stability. The simulation result reveals that the classical PID in series with second‐order filter incorporated with time delay compensation demonstrates acceptable closed‐loop performance with low IAE compare to standard direct synthesis method.

Dynamic Process Modeling of Topside Systems for Evaluating Power Consumption and Possibilities of Using Wind Power

Norwegian offshore wind farms may be able to supply power to offshore oil and gas platforms in the near future thanks to the expeditious development of offshore wind technology. This would result in a reduction in CO2 emissions from oil and gas offshore installations, which are currently powered predominantly by gas turbines. The challenge with using wind power is that offshore oil and gas installations require a fairly constant and stable source of power, whereas wind power typically exhibits significant fluctuations over time. The purpose of this study is to perform a technical feasibility evaluation of using wind power to supply an offshore oil and gas installation on the basis of dynamic process simulations. Throughout the study, only the topside processing system is considered, since it is the most energy-intensive part of an oil and gas facility. An offshore field on the Norwegian Continental Shelf is used as a case study. The results indicate that, when the processing system operates in steady-state conditions, it cannot be powered solely by wind energy, and another power source is required to compensate for low wind power generation intervals. An alternative would be to store wind energy during periods of high generation (e.g., by producing hydrogen or ammonia) and use it during periods of low generation. Utilizing energy storage methods, wind energy can be continuously used for longer periods of time and provide a suitable constant power source for the studied case. Higher constant power can also be provided by increasing the efficiency of energy recovery and storage processes. Alternatively, these two technologies may be integrated with gas turbines if the required storage cannot be provided or higher power is required. It was estimated that the integration of wind energy could result in noticeable reductions in CO2 emissions for the case study. Additionally, according to the results, the production, storage, and reuse of hydrogen and ammonia on-site may be viable options for supplying power.