Operating Conditions Research Articles

Hybrid modeling for in silico optimization of a dynamic perfusion cell culture process.

The bio-pharmaceutical industry heavily relies on mammalian cells for the production of bio-therapeutic proteins. The complexity of implementing and high cost-of-goods of these processes are currently limiting more widespread patient access. This is driving efforts to enhance cell culture productivity and cost reduction. Upstream process intensification (PI), using perfusion approaches in the seed train and/or the main bioreactor, has shown substantial promise to enhance productivity. However, developing optimal process conditions for perfusion-based processes remain challenging due to resource and time constraints. Model-based optimization offers a solution by systematically screening process parameters like temperature, pH, and culture media to find the optimum conditions in silico. To our knowledge, this is the first experimentally validated model to explain the perfusion dynamics under different operating conditions and scales for process optimization. The hybrid model accurately describes Chinese hamster ovary (CHO) cell culture growth dynamics and a neural network model explains the production of mAb, allowing for optimization of media exchange rates. Results from six perfusion runs in Ambr® 250 demonstrated high accuracy, confirming the model's utility. Further, the implementation of dynamic media exchange rate schedule determined through model-based optimization resulted in 50% increase in volumetric productivity. Additionally, two 5 L-scale experiments validated the model's reliable extrapolation capabilities to large bioreactors. This approach could reduce the number of wet lab experiments needed for culture process optimization, offering a promising avenue for improving productivity, cost-of-goods in bio-pharmaceutical manufacturing, in turn improving patient access to pivotal medicine.

Nonlinear flow modeling of electro hydrostatic pump unit based on Gauss Newton iterative method for high performance control

For the electric hydrostatic pump unit (EPU), which is a crucial component in the electro hydraulic servo pump control system (EHSPCS), nonlinear flow modelling is a key challenge to achieve high performance operation, especially in position control. For the nonlinear flow of EPUs, simple linearization combined with compensation has become a popular control method recently. However, the control performance is constrained by the reliance on deviation correction. This paper proposes utilizing the Gauss Newton iterative method to investigate the nonlinear flow modeling in the EPU, aiming to obtain the mapping relationship between the load flow and operating parameters in the EPU, thereby directly improving the control performance. A nonlinear flow model is built by utilizing the Gauss Newton iterative method based on test data obtained from various operating conditions, and the mapping relationship is presented accordingly. Experimental studies show that compared to well-established methods, this model exhibits high accuracy and practicality in improving the control performance, particularly in position control of the EPU.

A Wide-Range TCSC Based ADN in Mountainous Areas Considering Hydropower-Photovoltaic-ESS Complementarity

Due to the radial network structures, small cross-sectional lines, and light loads characteristic of existing AC distribution networks in mountainous areas, the development of active distribution networks (ADNs) in these regions has revealed significant issues with integrating distributed generation (DGs) and consuming renewable energy. Focusing on this issue, this paper proposes a wide-range thyristor-controlled series compensation (TCSC)-based ADN and presents a deep reinforcement learning (DRL)-based optimal operation strategy. This strategy takes into account the complementarity of hydropower, photovoltaic (PV) systems, and energy storage systems (ESSs) to enhance the capacity for consuming renewable energy. In the proposed ADN, a wide-range TCSC connects the sub-networks where PV and hydropower systems are located, with ESSs configured for each renewable energy generation. The designed wide-range TCSC allows for power reversal and improves power delivery efficiency, providing conditions for the optimization operation. The optimal operation issue is formulated as a Markov decision process (MDP) with continuous action space and solved using the twin delayed deep deterministic policy gradient (TD3) algorithm. The optimal objective is to maximize the consumption of renewable energy sources (RESs) and minimize line losses by coordinating the charging/discharging of ESSs with the operation mode of the TCSC. The simulation results demonstrate the effectiveness of the proposed method.

Advanced Phase Diversity Method for telescope static aberration compensation

Accurate calibration is essential for high-performance Adaptive Optics (AO) systems in astronomy. This paper presents a novel methodology for AO systems calibration that preserves the optical path integrity while achieving high-quality results. By eliminating the need for optical modifications, this approach simplifies system complexity and accounts for all static aberrations. The main novelty of this proposal is an advanced Phase Diversity (PD) method for estimating static optical aberrations. Unlike conventional PD techniques, this approach uses the AO system’s deformable mirror to introduce different diversities, eliminating the need for additional calibration hardware. Furthermore, the optimizer Adam is introduced for the first time in this field to estimate the optical aberrations. To evaluate the performance of this new methodology, a set of experiments under varying operating conditions and optimization parameters has been conducted. Results demonstrated that the presented methodology is capable of providing diffraction-limited corrected images with a Strehl Ratio (SR) exceeding 0.80 within 2 min. Furthermore, employing a Manhattan distance-based error function effectively balanced estimation speed and accuracy. The method demonstrated effectiveness across a wide range of aberration magnitudes, achieving an error of 3 nm in the best scenarios. This proposal represents an advancement in the identification and correction of static aberrations in telescope optical systems, directly improving the acquisition of high-quality references for AO sensing.

Optimization of Operating Conditions for Battery Thermal Management System

With the rapid increase in the number of vehicles worldwide, we are currently experiencing a scarcity of nonrenewable energy, such as fuel, and the resulting environmental risks associated with vehicle utilization [...]

Experiments on High-Temperature Irradiation of Li2ZrO3/MgLi2ZrO4 Ceramics by He2+ Ions

The key objective of this study is to determine the effect of interphase boundaries, the formation of which is caused by the variation of Li2ZrO3/MgLi2ZrO4 phases in lithium-containing ceramics based on lithium metazirconate, on the resistance to near-surface layer destruction processes associated with irradiation with He2+ ions. During the observation of the deformation effects that have an adverse impact on the volumetric swelling of the near-surface layers of ceramics, the thermal expansion factor caused by high-temperature irradiation was considered, simulating conditions as close as possible to the operating conditions of these materials as blankets for tritium propagation. During the studies conducted, it was established that an elevation in the contribution of MgLi2ZrO4 in the composition of ceramics leads to a rise in resistance to deformation swelling caused by structural distortions of the crystal lattice, due to a decrease in the effect of thermal expansion, alongside the presence of interphase boundaries. The established dependencies of the change in the hardness of the near-surface layer of the studied ceramics made it possible to establish the kinetics of softening caused by the deformation distortion of the crystalline structure, as well as to determine the relationship between volumetric swelling and softening (change in hardness) and a decrease in crack resistance (change in the value of resistance to single compression).

The Ultimate Fate of Reactive Dyes Absorbed onto Polymer Beads: Feasibility and Optimization of Sorbent Bio-Regeneration under Alternated Anaerobic–Aerobic Phases

Dyes employed in many production cycles are characterized by high toxicity and persistence in the environment, and conventional wastewater treatments often fail to reach high removal efficiencies. Consequently, there is an increasing research demand aimed at the development of more efficient and sustainable technologies. A two-step strategy consisting of dye sorption followed by sorbent bio-regeneration is proposed here, with a special focus on the regeneration step. The objective of this study was to establish the best operating conditions to achieve regeneration of dye-loaded polymers and concurrently the ultimate removal of the dyes. To this aim, the bio-regeneration of the Hytrel 8206 polymer, used as a sorbent material to remove Remazol Red dye from textile wastewater, was investigated in a two-phase partitioning bioreactor (TPPB) under alternated anaerobic–aerobic conditions. Comprehensive analysis of operational parameters, including sorbent load and initial contamination levels, was conducted to optimize bio-regeneration efficiency. Experimental data demonstrated high regeneration efficiencies (91–98%) with biodegradation efficiencies up to 89%. This study also examines the biodegradation process to investigate the fate of biodegradation intermediates; results confirmed the successful degradation of the dye without significant by-product accumulation. This research underscores the potential of TPPB-based bio-regeneration of polymeric sorbent material for sustainable wastewater treatment, offering a promising solution to the global challenge of dye pollution in water resources.

Research on the splitting tensile dynamic mechanics performance of post-high-temperature high-performance concrete

High-performance concrete (HPC) structures were affected by secondary hazards after a fire, research on its dynamic mechanics performance is vital for assessing post-disaster structural safety. Therefore, the mechanism which governs impact of coupling among high temperature, cooling mode and strain rate on the splitting tensile mechanics performance of HPC was delved; impact factors including five temperatures, two cooling modes and four strain rates were designed; digital image technology (DIC) and hydraulic servo instrument were adopted to investigate the splitting tensile mechanics performance of HPC with Brazilian disc. Failure mechanical parameters of HPC under varying operational conditions and full-field deformation parameters of the whole loading process were obtained. As indicated by research result, the splitting tensile strength of test specimens cooled naturally from 200 °C to 600 °C was higher than that of specimens cooled rapidly, while the splitting tensile strength under natural cooling from 800 ℃ decreased by 6 % compared with rapid cooling. At the same temperature, splitting tensile strength of HPC was gradually increased with the increase of strain rate, and Dynamic Increase Factor (DIF) was significantly increased, showing relatively high rate sensitivity. With increasing temperature, the increase in DIF for HPC declined somewhat. As revealed by the result of DIC analysis, at high temperature, damage was relatively mild at the development stage and entered the stage of abrupt change of strain field in a short time. With increasing strain rate, the overall damage duration of test specimen was significantly shortened, and cooling mode exerted no significant impact on the development of splitting tensile damage in HPC. The criterion for splitting tensile dynamic strength of post-high-temperature HPC was put forward on the basis of J criterion. Meanwhile, an analysis by backscattered electron (BSE) on microstructure of HPC revealed mechanism which governs the impact of high temperature and cooling mode on the splitting tensile dynamic mechanics performance of HPC. The research result serves as a theoretical basis for calculating and assessing the post-fire structural dynamic response of HPC.

Outdoor Performance Analysis of Semitransparent Photovoltaic Windows with Bifacial Cells and Integrated Blinds

The stricter requirements for the energy performance of buildings are creating a market for several building‐integrated photovoltaic (BIPV) technologies, including photovoltaic (PV) windows. Herein, an innovative multifunctional PV window concept designed to enhance energy generation while providing overheating protection for better indoor thermal and visual comfort is presented. This concept utilizes bifacial c‐Si solar cell strips combined with venetian blinds, all embedded in a unique insulating glazing unit. The bifacial technology increases the energy yield by using the blinds as reflectors, directing more irradiance to the cells’ rear side. The goal of this study is to analyze the outdoor performance of this concept under real operating conditions. Twelve demonstrators are installed and monitored. Various measurement campaigns are conducted, examining the impact of different blind types, tilt angles, sun positions and sky conditions. The highest energy boosts occur when the blinds are fully closed at a 75° angle with their convex side facing outward. Blinds with the highest specular reflectance achieve a maximum performance increase of 25% on sunny days and a daily average increase of 12% compared to the case of no blinds.

Research on the change of the combined moment of inertia for two-link manipulator with angular coordinate system

The main of the problems of the development of two-link manipulators with an angular coordinate system is the lack of effective and universal control systems capable of implementing energy-intensive modes of movement. This is due to the design features of the pointer system of such manipulators and the methods of their use. During the operation of the manipulator, significant dynamic loads occur in its drive system, which create oscillations of the mechanical system and reduce the accuracy of work. The control system must also effectively compensate for such dynamic variations. Dynamic equations of motion used to build manipulator control controllers, which allow taking into account various features of using manipulators. These mathematical models necessarily contain one of the characteristics in the form of the combined moment of inertia of the mechanical system, which is important in the calculation of differential equations and the determination of kinematic parameters of motion. In this article, the combined moments of inertia of the boom system of a two-link manipulator with an angular coordinate system are determined. A study was carry out and it shown that the nature of the change in the combined moments of inertia influenced by the modes of movement of the boom system links. The results of the study showed that the combined moment of inertia of the boom system of the manipulator is not a constant value, which does not change uniformly under special operating conditions of the machine. To determine the combined moments of inertia, the method of bringing the kinetic energy of the moving system to the drive mechanism was apply. This is relevant, because in the future it will be necessary to adjust the unevenness of the movement of the manipulator links by the drive itself. The study was conduct for a typical linear motion mode and a motion mode with a change in speed along a parabolic trajectory.

Investigation of operational settings, environmental conditions, and faults on the gas turbine performance

Abstract Gas turbine engines are complex mechanical marvels widely employed in diverse applications such as marine vessels, aircraft, power generation, and pumping facilities. However, their intricate nature renders them susceptible to numerous operational faults, significantly compromising their performance and leading to excessive emissions, consequently incurring stringent penalties from environmental regulatory bodies. Moreover, the deterioration of gas turbine performance is exacerbated by variations in working conditions based on operational settings and environmental conditions. Past studies have focused on certain working conditions that limit effectiveness in real-world applications where operational settings and environmental conditions vary during operations. The influence of these working conditions on the performance of gas turbines also needs to be assessed, as they can lead to different fault patterns resulting in unplanned maintenance, unnecessary maintenance costs, unsafe conditions and stringent penalties. This study uses the gas turbine simulation program to simulate a high-bypass turbofan engine inspired by Pratt & Whitney PW-4056, analysing the combined effects of operational settings and environmental conditions on engine performance while also incorporating simulations of common gas turbine faults like fouling and erosion in various locations and severities along the gas path. The model’s accuracy is confirmed by low mean absolute percentage errors of 0.004% of thrust at the cycle reference point and 0.15% and 0.28% at 2 km and 7 km altitudes, respectively, demonstrating the model’s robustness across varying operational scenarios. In conclusion, this research highlights the significant effects of operational settings and environmental factors on gas turbine performance, particularly impacting specific fuel consumption and thrust. The study reveals that operational settings and environmental factors significantly impact fuel consumption and thrust. Specifically, compressor fouling and low-pressure turbine erosion increase nitrogen oxide (NOx) emissions by 4.5% and 11.1%, while fouling of nozzle guide vanes and high-pressure turbine erosion raise unburned hydrocarbon by 10.0% and 20.2%, and carbon monoxide (CO) by 3.2% and 5.2%, respectively, compared to a healthy engine. These insights highlight the importance of component-specific degradation in influencing gas turbine performance and emissions.

Efficiency enhancement of photovoltaic-thermoelectric generator hybrid module by heat dissipating technique

Exploring substantial solar irradiation and recuperating excess heat generated during photovoltaic energy conversion is a critical issue. The efficiency of photovoltaic systems (PV) is significantly depend on the increased operating temperatures encountered by solar radiation. One conceivable option for improving the conversion of solar energy is to integrate a photovoltaic (PV) panel with a thermal-electric generator (TEG) material module to create a hybrid system. This study proposed a parallel PV-TEG hybrid module that effectively harvests the maximum solar energy spectrum while maximizing the use of heat generated by the thermoelectric material to improve the overall system efficiency. The proposed module consists of a photovoltaic unit, thermoelectric material module and passive cooling of fluid channels. The aim of this work was to develop a PV-TEG hybrid system and create an energy simulation model in a MATLAB environment to analyze the model's performance under various operational conditions by applying both theoretical and experimental approaches. Findings showed considerable concurrence. At 13:00, when the PV surface temperature was 54 °C, the PV efficiency reached to its lowest value of 12.0 %. Nevertheless, the highest TEG efficiency recorded was 4.7 % at 12:00 h. The efficiency of the TEG module was significantly affected by weather conditions, inlet cooling water temperature, and fluid flow rate in comparison to both the PV efficiency and the thermal efficiency.

Catalytic evaluation of eggshell‐based calcium methoxide over Al2O3 for biodiesel generation from waste cooking oil

AbstractShell‐derived materials are promising heterogeneous catalysts for biodiesel production due to their nontoxic and renewable nature, but they have the disadvantage of being highly leachable. To overcome this issue, Ca(OCH3)2 formed through the reaction of CaO with methanol, and supported in turn on Al2O3 is proposed as a catalytic system for the transesterification of fresh soybean oil and waste cooking oil (WCO). First, catalysts with several Al/Ca molar ratios (0.2, 0.5, and 0.8‐AC), as well as their precursors (CaO and Al2O3) alone, were tested at 60 °C, catalyst loading 6% wt, methanol‐to‐oil molar ratio (MOR) 10, for 1 h for fresh oil, and 3 h for WCO. The 0.2‐AC catalyst generated the highest biodiesel yield for both oils. The optimum operating conditions for WCO transesterification, determined by using a univariable approach, were 60 °C, 9 wt% catalyst loading, MOR of 12.5, and a reaction time of 3 h. These improved conditions led to yields higher than 90% for pure CaO and the 0.2, 0.5, and 0.8‐AC catalysts. The density, kinematic viscosity, and refractive index of the biodiesel obtained were measured.

Combustion Process of Coal–Açai Seed Mixtures in a Circulating Fluidized Bed Boiler

This study investigates the effects of the co-combustion of coal and açai seed in circulating fluidized bed (CFB) boilers, highlighting the increase in thermal efficiency and relevance of a less-polluting source of energy. Using the computer software 1.5D CeSFaMB™® v4.3.0, simulations of the co-combustion process of coal and biomass were carried out in a CFB boiler, obtaining results such as the temperature profile, boiler efficiency and emissions. The work acquired data regarding the equipment in real operational conditions, consisting of the fundamental geometric and operational parameters used in the simulation campaign. The thermal and chemical properties of the fuels were analyzed by carrying out proximate, ultimate, heating value, particle size and specific mass analyses. The model validation was achieved by simulating the boiler in its real operating conditions and comparing the obtained results with the real data; the obtained error was below 10%. Simulations with different fractions of açai seed for energy replacement (10% and 30%) were carried out. As a result, an increase in the average temperature of the bed was observed, highlighting the region immediately above the dense bed. An increase in boiler efficiency was verified from 56% to 85% with 10% açai and to 83% with 30% açai seed. Decreases in SO2 and CO emissions with the insertion of açai were obtained, showing that co-combustion is more complete, while CO2 emissions were increased due to the higher quantity of fuel inserted into the equipment. The fossil CO2 emissions were reduced.

Fault Intelligent Diagnosis for Distribution Box in Hot Rolling Based on Depthwise Separable Convolution and Bi-LSTM

The finishing mill is a critical link in the hot rolling process, influencing the final product’s quality, and even economic efficiency. The distribution box of the finishing mill plays a vital role in power transmission and distribution. However, harsh operating conditions can frequently lead to distribution box damage and even failure. To diagnose faults in the distribution box promptly, a fault diagnosis network model is constructed in this paper. This model combines depthwise separable convolution and Bi-LSTM. Depthwise separable convolution and Bi-LSTM can extract both spatial and temporal features from signals. This structure enables comprehensive feature extraction and fully utilizes signal information. To verify the diagnostic capability of the model, five types of data are collected and used: the pitting of tooth flank, flat-headed sleeve tooth crack, gear surface crack, gear tooth surface spalling, and normal conditions. The model achieves an accuracy of 97.46% and incorporates a lightweight design, which enhances computational efficiency. Furthermore, the model maintains approximately 90% accuracy under three noise conditions. Based on these results, the proposed model can effectively diagnose faults in the distribution box, and reduce downtime in engineering.

Optimizing Wireless Power Transfer Systems: A Simulation-Based Approach Using CST Studio Suite

In the rapidly evolving field of wireless power transfer (WPT), achieving systems that combine efficiency with reliability is crucial. This paper presents a simulation-based approach using CST Studio Suite to optimize WPT systems for wireless battery chargers in electric bikes. The study fixes the size of both the transmitter and receiver coils, the spacing between turns, and the number of coil turns, with a set distance of 20mm between the transmitter and receiver coils. CST Studio Suite is employed to determine the parameters of resonance capacitors and the optimal switching frequency to enhance WPT efficiency. This powerful simulation tool allows researchers and engineers to design resonance compensation circuits more effectively, optimizing power transfer efficiency. The simulation conducted with CST Studio Suite confirms its effectiveness in designing a WPT system, achieving an impressive peak efficiency of 99.61% at the resonant frequency. The paper demonstrates CST Studio Suite's capability to accurately predict WPT system performance by developing detailed electromagnetic models and fine-tuning simulation parameters to reflect real operating conditions. Iterative simulations resulted in optimized practices, validated by select results that highlight the method's effectiveness and showcase an optimal balance between system complexity and efficiency. These findings provide a strategic framework for future WPT system development, offering practical guidance for researchers and industry professionals aiming to advance WPT technology.

Optimization of aero-engine condition monitoring by autoregressive model analysis based on wireless communication

The high value of aero-engines makes it necessary to extend their life in terms of econ-omy of use. Health management is an important basis for this work. Background: The vibration signal is an important representation of the working state of an aero-engine. The current usual method is based on wired communication with simple waveform presentation. The many incon-veniences of this method have seriously affected the further development of this work. Methods: This research team acquires engine vibration signals in real time through a designed wireless signal sensor, and then analyzes and visualizes the signals in depth. Results: Through this method, it can visually and effectively demonstrate signal characteristics for engineers, effectively identify fault signals, and monitor engine operating conditions in real time. Conclusions: The method enables the optimization of aero-engine work-state monitoring.

Electro-activation for efficient lactulose production: The impact of operational parameters, electrolyte types, and environmental conditions

The electro-activation (EA) process has been employed to convert lactose into lactulose, a potent prebiotic with numerous health benefits. The study identified optimal conditions for lactulose production, including a specific current density, the use of calcium chloride as an efficient electrolyte, and the superiority of a steel cathode over a graphite cathode. The formation of intermediates other than lactulose increased as the temperature increased. The changes in pH and oxidation-reduction potential during the isomerization process were observed, highlighting their vital role in the formation of an ideal alkaline environment for lactulose production. The resultant solution produced by the EA process has significant antioxidant characteristics, likely due to the formation of Maillard Reaction Products during lactulose production. In conclusion, the EA system, with optimal operating conditions, is an energy-efficient, reagent-free, and environmentally friendly alternative for lactulose production.

Impact of variable hydrostatic pressure and intermittent operation on filtration performance and biofouling layer in gravity-driven membrane system for practical decentralized water supply

The gravity-driven membrane (GDM) systems offer a promising solution for decentralized drinking water supply due to its low maintenance and energy consumption. However, research on the practical application of GDM under variable hydrostatic pressure (variable load) and intermittent operation conditions, particularly in response to high-turbidity water, remains limited. This study investigates the long-term performance and characteristics of the biofouling layer of GDM under ultra-low variable hydrostatic pressure (20–60 mbar) and intermittent operation (8–12 h) conditions in practical decentralized water supply. The results indicate that the membrane flux (1.9–6.0 L∙m−2∙h−1, LMH) remained relatively stable despite variations in gravity-driven pressure (ΔP). Long-term operation of GDM can stably remove turbidity and potential pathogens from raw water. The total protein/polysaccharide ratios of extracellular polymeric substances (EPS) in the biofouling layer were below 0.50, reducing contaminant adhesion on the membrane surface. The 0.2–0.4 μm transparent exopolymer particles (TEP) fraction might be crucial for biofouling layer formation. The key species, belong to Proteobacteria and Patescibacteria, significantly alleviated membrane fouling by degrading polysaccharide and proteins in biofouling layer. Comammox Nitrospira were significantly enriched, contributing to efficient nitrification. GDM with variable load maintained a stable flux of 2.2–5.2 LMH under high-turbidity water conditions (300–1200 NTU), and simple forward flushing combined with sludge discharge can quickly restore ΔP. Overall, the variable load GDM system effectively manages membrane fouling and maintains stable filtration performance through the combined effects of variable load and intermittent operation, ensuring long-term and low-maintenance operation for decentralized water supply.

Flexible curved multi-functional sensors for air flow and vibration signal measurement of train bogie

Abstract The fluid-solid coupling effects with the aerodynamic noise and structural vibration signal have great part in measurement accuracy and fault diagnosis of the train bogie. It is important to collect aerodynamic noise and structural vibration data for safety evaluation and on-line structural health monitoring (SHM) of the bogie, which brings new challenges to the integration and installation of the sensors in the limited space and complicated operation condition of the train bogie. Flexible curved multifunctional sensors (FCMFS) integrated with the hot film and structural vibration sensor units is designed to the air flow and structural vibration measurement of the train bogie. Bogie vibration and wind tunnel test platforms with FCMFS are built to the air flow velocity and vibration data measurement on the bogie surface under different operation conditions. Piezoelectric Polyvinylidene fluoride(PVDF) sensors have significant output in the wind tunnel and vibration experiments, and the hot film sensor is only sensitive to the air flow signal. The effect of vibration signal to the hot film sensor could be ignored, which is applied to decouple the aerodynamic noise and structural vibration signals for improving the measurement accuracy of the train bogie. The dynamic performance of FCMFS is verified in Rail Transmit Base of East China Jiaotong University, which is applied to SHM and rapid fault diagnosis of train bogie. The air flow distribution and vibration data are collected to safety assessment and fault diagnosis of train bogie, which would promote the intelligent maintenance level of the train bogie.