An investigation of primary water sources in two Bolivian basins identified the presence of heavy metals toxic to health that exceeded the permissible limits for drinking water. Lead deposited in the San Jacinto and Huacata−Tarija reservoirs within the Guadalquivir basin and arsenic in the Milluni−La Paz basin were identified. The work studies reverse osmosis (RO) to remove Pb and As. The main contribution of this research is the development and construction of a mathematical model based on the Spiegler−Kedem concentration polarization model using different concentrations of Pb and As. The model makes it possible to design high conversion facilities (>80%) and optimize the process from the point of view of energy efficiency in future works. The model was developed to also include an Arrhenius temperature adjustment factor that allows for an accurate prediction of the process performance. The experimentation was carried out in two RO pilot plants using polyamide membranes. The model fit... [more]

Neutral Point indicates the flux formula where no transfer of alloying element between the flux and weld metal occurs. For the submerged arc welding process, Neutral Point is an essential definition for flux design and specification since it helps to identify the flux microalloying ability. The scientific hypothesis that the Neutral Point is only a function of the flux formula is considered as the basis of the Mitra kinetic model. Within this framework, by performing submerged arc welding with CaF2-SiO2-Na2O-MnO agglomerated fluxes under various heat inputs, the moving of Neutral Point has been captured, indicating the scientific hypothesis proposed in Mitra kinetic model may be revised under high heat input welding. Additionally, although some studies have incorporated the consideration of the gas-slag-metal equilibrium, only the effective equilibrium temperature of 2000 or 2100 °C is utilized, which may be insufficient to constrain Mn content in the weld metal. In this study, we have... [more]

The accumulation of process waste in the production line causes fluctuations, bottlenecks, and increased inventory in workstations disrupting process flow. In this paper, the optimal process flow that will improve productivity using simulated value stream mapping (SVSM) for decision-making to provide consistency, minimise errors and non-value adding times in the implementation phase of VSM in the truck manufacturing industry. The proposed methodology applied a discrete event simulation for production process operations improvement to eliminate non-value adding times and provide good quality products at the lowest cost and highest efficiency. The results are the analysis of the current state of the production system in a South African truck manufacturing industry as a potential solution for the production system’s future state. The identified non-value adding times in the six most critical workstations were eliminated by SVSM resulting in a productivity improvement of 4%, most important... [more]

In this review, the condensation HTCs (heat transfer coefficients) and pressure drop characteristics of some major low-global-warming-potential (GWP) refrigerants alternative to R-134a such as R-1234ze(E), R-1234ze(Z), R-1234yf, R-513A, and R-450A are reviewed. The thermofluids’ characteristics inside/outside a tube, minichannel, microfin tube, and plate heat exchanger are examined. In addition, several other refrigerants attributed to low GWP are also included in the present review. The experimental/numerical/simulation results’ analysis reveals that condensation HTCs and pressure drop characteristics depend on several parameters such as thermodynamics and transport properties of the working fluid, mass flux of the refrigerants, heat flux, saturation temperature, vapor quality, flow patterns, flow conditions, orientation of the condensing geometry, and condensation geometry (shape, size, and smooth/enhanced).

The temperature shrinkage effect is a very important factor causing the cracking of super-long frame structures. Current design codes and recommendations for reinforced concrete (RC) structures consider the influence of the construction process on the temperature shrinkage effect by adopting a uniform reduction coefficient and neglect the influence of the construction method. However, different construction processes can vary the temperature stress of the structure. In this paper, under cooling action, the temperature stress of a one-layer, super-long frame structure with different quantities and indwelling times of post-cast strips is calculated with a spatial nonlinear simulation analysis program by adopting the degenerated spatial solid virtual laminated element method. With this approach, the internal force state of each construction stage during the construction process is accounted for in a nonlinear mechanical model of the structure. The results show that the quantity and the in... [more]

Thirteen benzothiazolone derivatives (M1−M13) were synthesized and evaluated for their inhibitory activity against cholinesterases (ChEs) and monoamine oxidases (MAOs). All the compounds inhibited ChEs more effectively than MAOs. In addition, most of the compounds showed higher inhibitory activities against butyrylcholinesterase (BChE) than acetylcholinesterase (AChE). Compound M13 most potently inhibited BChE with an IC50 value of 1.21 μM, followed by M2 (IC50 = 1.38 μM). Compound M2 had a higher selectivity index (SI) value for BChE over AChE (28.99) than M13 (4.16). The 6-methoxy indole group of M13 was expected to have a greater effect on BChE inhibitory activity than the other groups. Kinetics and reversibility tests showed that M13 was a reversible noncompetitive BChE inhibitor with a Ki value of 1.14 ± 0.21 μM. In a docking simulation, M13 is predicted to form a hydrogen bond with the backbone carbonyl group of Ser287 of BChE through its methoxy indole moiety and π−π interaction... [more]

In this work, the computational particle fluid dynamics (CPFD) method is used to simulate the high-pressure visual fluidized bed experimental equipment independently designed and developed by the experimentation of the fluidized reduction process of iron ore powder. A numerical model for reducing iron ore fines in a three-dimensional fluidized bed is established, and the model is verified by combining numerical simulation and experimental testing. Moreover, the influences of different reducing factors on the reduction effect in the process of the fluidized reduction of iron ore fines are simulated in detail. Via the CPFD simulation of the fluidized reduction of iron ore fines, the optimal reduction pressure is found to be 0.2 MPa, and the optimal reducing gas is found to be H2. Moreover, the optimal gas velocity is 0.6 m/s, and the optimal reduction temperature is 923 K. This conclusion is consistent with the experimental measurements, so the simulation results can be used to verify th... [more]

A cold-flow lab-scale cross-flow fluidized bed classifier was simulated using the CFD software Barracuda VR®. The purpose of the study was to identify the most suitable drag model and make the model adjustments that provide the best representation of the flow situation in the classifier when comparing the results with the experimental data. Two particle types were used in the simulations and in the experiments: zirconia (median diameter 69 µm, skeletal density 3830 kg/m3) and steel (290 µm, 7790 kg/m3). Ten different cases, with different solids loading values, were investigated: three with pure zirconia particles, three with pure steel particles, and four with a mixture of zirconia (28%) and steel (72%). Several different drag models were tried out in the simulations. However, none of the available models were able to predict the classification efficiency observed in experiments with their default settings. Although most of the drag models correctly predicted the inversely proportiona... [more]

From a thermodynamic perspective, the present study has been performed to investigate the effect of SiO2 level in agglomerated fluxes on the element transfer behavior of essential elements, by applying CaF2-Na2O-SiO2 agglomerated fluxes with varying SiO2 contents. Element transfer behavior is quantified by the Δ value. The impact of SiO2 and heat input upon element transfer behavior is interpreted. Additionally, a possible thermodynamic approach to predict high basicity flux O potential and weld metal composition is proposed and evaluated. It is revealed that the consideration of the gas-slag-metal equilibrium is able to place constraints on the transfer behaviors (of O, Si, and Mn) and formation of gases. In submerged arc welding metallurgy, the empirically determined basicity index models proposed by Tuliani have been applied for more than 50 years to predict flux O potential and weld metal oxygen content. However, it is well known by welding practitioners that the flux basicity inde... [more]

Due to the continual fusion reaction, the sun generates tremendous energy. This solar energy is freely available and can be extracted by installing a large-scale solar power plant. Therefore, such PV solar plants are key contributors to cutting the energy deficit in remote areas. This study focused on predicting a 10-year performance analysis of a large-scale solar power plant by using 1 year of real-time data from the Quaid-e-Azam Solar Park (QASP) situated in Bahawalpur, Pakistan. For the purpose of prediction, the ARIMA model was developed using Python, which is one of the best tools in machine learning. Since ARIMA is a statistical technique for prediction, by using the developed model through Python, we predicted the values of the performance ratio (PR), production amount (MWh), and plan of array (POA) of the solar plant for the next 10 years using 1 year of real-time data. This machine learning prediction technique is very effective and efficient, compared with other traditional... [more]

The hydrodynamic characteristics of a rod-shaped squirmer swimming near a wall were studied numerically using the immersed boundary-lattice Boltzmann method in the swimming Reynolds number range of 0.1 ≤ Res ≤ 2.0, where the number of assembled squirmers was 2 ≤ i ≤ 4 and the distance between two adjacent assembled squirmers was 0.75 d ≤ s ≤ 1.5 d (d is the diameter of a single squirmer). The effect of Res, i and s on the swimming mode of the squirmer was explored. The results showed that there are four swimming modes after the first collision between the rod-shaped squirmer and the wall. There are also four swimming modes when Res changes from 0.1 to 2.0. Puller, pusher and neutral squirmers showed different swimming modes when i changed, and the effect degree of the flow at the previous moment on the squirmer’s motion was different for different values of i. The change in s only affected the trajectory of the squirmer without changing its motion mode. Puller, pusher and neutral squir... [more]

Carbon Capture and Storage (CCS) technology has attracted increasing attention as global climate change accelerates. Carbon dioxide removal processes under development include pressure swing adsorption (PSA) and chemical absorption using amine solvents. In this paper, an ammonia solvent, which is relatively inexpensive and has good material properties, was used instead of amines in the carbon dioxide removal process simulation as a chemical absorption method. This simulation used the eNRTL thermodynamics model which has the advantage of predicting ions in the liquid phase in Aspen Plus. A case study (Case Study 1) was conducted to verify the validity of the thermodynamic model. The purpose of this research was to find the operating conditions to eliminate more than 90% of the carbon dioxide contained in the flue gas from coal-fired power stations, and to lower heat duty and operating cost conditions. A second case study (Case Study 2) was conducted to find the operating conditions by c... [more]

The propellant gas flow of a supersonic rocket in inappropriate operating conditions can cause excessive ablation inside a nozzle. In this research, conjugate heat transfer analysis (CHTA), consisting of computational fluid dynamics (CFD) and finite element analysis (FEA), was applied to investigate the gas flow and ablation of a 122 mm nozzle as a case study in the transient state, based on actual operating conditions. First, the nozzle was tested in a static experiment. Then, the experimental results were employed for CHTA settings and validation. Next, after completing the CFD calculation, the results revealed that the nozzle’s gas flow, temperature, pressure, Mach number, shock, etc. were consistent with theoretical results. Finally, using the CFD results as loads, the FEA results showed the equivalent von Mises stress (σv), which was consistent with the ablation results from the experiment, as expected. The more the σv, the greater the ablation. Both σv and ablation were high near... [more]

Butyl acetate (BuAc) is widely used as a solvent in many applications, mainly in the food and pharmaceutical industries. The conventional process for BuAc production is both capital and energy intensive. The purification process involves the separation of BuAc from the azeotropic mixture of water and n-butanol, which is difficult to accomplish using a simple distillation unit. In this study, a membrane reactor (MR) for BuAc production via the esterification of n-butanol was investigated. The MR using the Amberlyst-15 catalyst was modeled and validated with previously reported experimental data, and a good agreement was achieved. The ultimate conversion of n-butanol using the MR was 92.0%, compared to 69.8% for the conventional reactor. This study is the first to propose an intensified MR-based process for butyl acetate production. The MR-based process was developed and rigorously simulated using Aspen Plus for an annual plant capacity of 92,500 metric tons of BuAc. The MR-based process... [more]

The mechanical characterization of adipose tissues is important for various medical purposes, including plastic surgery and biomechanical applications, such as computational human body models for the simulation of surgical procedures or injury prediction, for example, in the evaluation of vehicle crashworthiness. In this context, the measurement of human subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) mechanical properties in relation to subject characteristics may be really relevant. The aim of this work was to properly characterize the mechanical response of adipose tissues in patients with obesity. Then, the data were exploited to develop a reliable finite element model of the adipose tissues characterized by a constitutive material model that accounted for nonlinear elasticity and time dependence. Mechanical tests have been performed on both SAT and VAT specimens, which have been harvested from patients with severe obesity during standard laparoscopic sleeve gas... [more]

In recent years, monoclonal antibodies (mAbs) are gaining a wide market share as the most impactful bioproducts. The development of mAbs requires extensive experimental campaigns which may last several years and cost billions of dollars. Following the paradigm of Industry 4.0 digitalization, data-driven methodologies are now used to accelerate the development of new biopharmaceutical products. For instance, predictive models can be built to forecast the productivity of the cell lines in the culture in such a way as to anticipate the identification of the cell lines to be progressed in the scale-up exercise. However, the number of experiments that can be performed decreases dramatically as the process scale increases, due to the resources required for each experimental run. This limits the availability of experimental data and, accordingly, the applicability of data-driven methodologies to support the process development. To address this issue in this work we propose the use of digital... [more]

Vaccine supply has a bottleneck in manufacturing capacity due to operation personnel and chemicals needed. Assessment of existing mRNA (messenger ribonucleic acid) vaccine processing show needs for continuous manufacturing processes. This is enabled by strict application of the regulatory demanded quality by design process based on digital twins, process analytical technology, and control automation strategies in order to improve process transfer for manufacturing capacity, reduction out-of-specification batch failures, qualified personnel training and number, optimal utilization of buffers and chemicals as well as speed-up of product release. In this work, process control concepts, which are necessary for achieving autonomous, continuous manufacturing, for mRNA manufacturing are explained and proven to be ready for industrialization. The application of the process control strategies developed in this work enable the previously pointed out benefits. By switching from batch-wise to cont... [more]

The production of food is highly complex due to the various chemo-physical and biological processes that must be controlled for transforming ingredients into final products. Further, production processes must be adapted to the variability of the ingredients, e.g., due to seasonal fluctuations of raw material quality. Digital twins are known from Industry 4.0 as a method to model, simulate, and optimize processes. In this vision paper, we describe the concept of a digital food twin. Due to the variability of the raw materials, such a digital twin has to take into account not only the processing steps but also the chemical, physical, or microbiological properties that change the food independently from the processing. We propose a hybrid modeling approach, which integrates the traditional approach of food process modeling and simulation of the bio-chemical and physical properties with a data-driven approach based on the application of machine learning. This work presents a conceptual fra... [more]

A coupled reservoir/wellbore simulator is essential for solving relevant flow phenomena with dynamic interactions between reservoir and wellbore in two-phase flow systems. A reservoir simulator or wellbore simulator alone fails to solve these transient flow phenomena. This paper summarises a critical review of the coupled reservoir and wellbore simulation. First, a wide application of the drift-flux (DF) models to simulate gas−liquid flow in a wellbore model coupling to a reservoir model was discussed. Then, the mechanisms of the coupled reservoir/wellbore simulator in two-phase flow systems were discussed, including the reservoir modeling, wellbore modeling, and their coupling schemes. Various examples of representative coupled simulators were presented. Finally, some case studies were reported to reveal dynamic interactions between wellbore and reservoir by using the coupled reservoir/wellbore simulators. This study gives the most up-to-date and systematic sights on the relevant rese... [more]

Passive heat dissipation cooling technologies based on natural convection in open channels can effectively control the maximum temperature and improve the temperature homogeneity of 5G base stations, data centers and other equipment. In this paper, the flow and heat transfer of natural convection in an open-ended square channel with two suspending heat sources are studied through numerical simulation. The distributions of the temperature field and flow field in the channel with different horizontal distances and vertical altitude differenced of the heat sources are acquired via the finite element method (FEM)-based COMSOL Multiphysics. The changes in local temperature and the local Nusselt number are obtained. The relationships between the temperature field, flow field, and Nusselt number with respect to the geometric parameters of the heat sources are discussed. With different geometric parameters of the two suspending heat sources, the average surface temperature at the bottom is alw... [more]

Managing change in organizations is a laborious task that consumes value added time in various segments of the product lifecycle including design and development, production, delivery, and product disposition. Product lifecycle management plays an important role in minimizing the time required for managing engineering changes. This research aims to perform an extensive survey of the literature in this area. There is no consolidated review available in this area summarizing advances in engineering change management vis-à-vis product lifecycle management. Thus, the paper gives an overview of product lifecycle management-based thinking and change management. This review puts forward the most relevant research regarding the practices and frameworks developed for managing engineering change in an organization. These include model-based definition, digital twin, process-based semantic approach, service-oriented architecture, Unified Modeling Language, and unified feature modeling. The gaps b... [more]

Bacterial communities living in the soil can affect forests natural regeneration, but the effects of their composition and network inference on regeneration of Larix principis-rupprechtii Mayr plantations remain largely elusive. Therefore, the redundancy analysis and structure equations modeling of affecting elements for the regeneration of L. principis-rupprechtii plots including the diversity, composition and network structure of soil bacteria, topographic factors, light factors, and soil physicochemical properties have been conducted. It was found that the increased modularity of the soil bacterial community co-occurrence network and the enrichment of metabolic pathway bacteria had a significant positive effect on the successful regeneration (total effect of 0.84). The complexity of the soil bacterial community gradually decreased with the increase of stand regeneration, and the composition and structure of the flora became simpler (with standard path coefficients: −0.70). In additi... [more]

It is quite important to clearly understand the fluid dynamic process of water droplets impacting on a hot extracted titanium tailings surface for the recovery and utilization of tailings. In this research, the finite volume simulations of the droplet impingement were developed by applying the volume-of-fluid method and were validated against experimental results. Droplet-impact experiments were performed by using a high-speed camera. The effects of the Weber number, surface tension value, and contact angle on the spreading factor were quantitatively investigated, and the distributions of pressure, velocity contour, and temperature were analyzed in detail during the impact process. We found that the numerical results of the impact process and spreading factor conform to the experiments. Moreover, the surface tension, contact angle, and Weber number have important consequences for droplet dynamic characteristics. Finally, a new maximum spreading factor model that is governed by Weber nu... [more]

Monoethylene glycol (MEG) is used to produce polyester fibers and polyethylene terephthalate resins. It is also utilized in antifreeze, pharmaceuticals, and cosmetics applications. In this research, we consider the development of a novel process plant that produces MEG from ethylene. The proposed ethylene-to-ethylene oxide (EO) plant is integrated with an EO-to-MEG plant to reduce utility costs and recover high-value products. Energy-saving opportunities are analyzed via heat integration tools. Furthermore, a multitube glycol reactor is used in conjunction with a novel MTO catalyst in the ethylene-to-EO reactor. Our results demonstrate that the integrated EO/EG plant produces ethylene glycols with that same purity and product recovery as conventional designs. A comparative economic assessment based on a 200,000 t/y plant indicates that process integration techniques can reduce costs significantly.

Sulfur deposition has an important effect on the productivity of sour-gas wells. Accurately predicting the occurrence of sulfur deposition and the location and amount of sulfur deposition in wellbore can effectively guide the production of gas wells. In this paper, the wellbore sulfur deposition model, pressure model, and transient temperature model are established for various well types. Then, numerical simulations of sulfur deposition in the sour-gas well were conducted by coupling these models. Examples show that the proposed methodology has high accuracy, and the average relative error of the calculated results is 3.61%. Based on the model, a sensitivity analysis was performed on the factors affecting sulfur deposition. The results show that with the increase of wellbore inclination angle, the critical sulfur carrying velocity first increased and then decreased, and the maximum critical velocity is about 30% larger than that of the vertical section. The amount of wellbore sulfur de... [more]