Operating Pressure Research Articles

Performance of machine learning versus the national early warning score for predicting patient deterioration risk: a single-site study of emergency admissions

ObjectivesIncreasing operational pressures on emergency departments (ED) make it imperative to quickly and accurately identify patients requiring urgent clinical intervention. The widespread adoption of electronic health records (EHR) makes rich...

Experimental study on the transcritical cycle performance of a closed-loop heat pump drying system based on R744/R290/R32 ternary refrigerant

Given the issue of high operating pressure in CO2 transcritical cycles, this paper proposes a novel non-combustible and low-GWP R744/R290/R32 ternary refrigerant used for heat pump drying systems. Six different mass ratios of the R744/R290/R32 are determined based on the limits posed by non-flammability and low GWP, and the transcritical cycle performance of these mixed refrigerants and pure CO2 applied to a closed-loop heat pump drying system (HPDS) at various drying air supply temperatures (DAST) is studied and compared experimentally. The analytic hierarchy process is used to assess the weights of the evaluation indices. Based on the experimental data, comprehensive scores for seven refrigerants are calculated, leading to the determination of the optimal mass ratio. The results show that at the same DAST, compared to pure CO2, the discharge pressure of the HPDS using the six mixed refrigerants decreases, and the COP increases. The optimal R744/R290/R32 mass ratio is 0.741/0.06/0.199. When the HPDS uses this, the compressor discharge pressure, heating capacity, moisture extraction rate (MER), and specific moisture extraction rate (SMER) decrease by an average of 14.8 %, 7.7 %, 17.6 %, and 0.06 %, respectively, while the COP increases by 4.9 % to 12.4 %. These research results can provide a reference for the development of new environmentally friendly refrigerants and their systems in the heat pump drying field.

Multi-objective hierarchical energy management strategy for fuel cell/battery hybrid power ships

The energy management strategy and the local controller in the ship energy management system are interconnected, impacting the performance of the hybrid propulsion system. To achieve the efficient operation of the hydrogen fuel cell (FC) and battery hybrid power system, based on the modelling and analysis of the hybrid power system, a nonlinear model predictive control (NMPC) based energy management strategy is proposed, and a dynamic virtual impedance droop controller and a classical proportional-integral (PI) controller are designed as local controllers. By simulating the designed random load conditions, pulse load conditions, and actual sailing conditions using hardware-in-the-loop (HiLs) technology, six different energy management strategies and their comprehensive performance with local controllers are compared and analysed. Comparing performance in terms of energy consumption, operating pressure, control accuracy, real-time performance, and robustness, it has been proven that the energy management strategy based on NMPC, coupled with a PI controller, is superior to other strategies overall. It can balance hydrogen consumption and the stable operation of the hybrid power system. Compared to existing energy management strategies, the proposed NMPC+PI strategy can reduce hydrogen consumption by 7.00 % and 40.29 %, and FC operating pressure by 44.96 % and 49.88 %, respectively, under both designed navigation conditions and actual navigation conditions.

Comparative optimization of the thermal performance for H2 – Metal hydride heat storage and heat pump systems

Metal hydride is very promising in hydrogen storage and simultaneously the thermal effect in the reversible hydrogenation process makes it possible in heat storage and heat pump area. The interaction of H2 – Metal – hydride pair and its further applications need comprehensive thermodynamic design and performance optimization. Therefore, this work makes thermodynamic comparative research of heat storage and heat pump systems by adopting H2 – Metal-hydride pair. According to the investigation, the thermodynamically optimal charging-discharging temperatures (Tm1,Tm2), the heat source temperature (Th1) and the ambient temperature (Tc1) meet the relationship of Tm1Tm2=Th1Tc1 for the heat storage system. Given the operating pressure (p), there exists a well-matched temperature (T) range to maximize the exergy performance of metal hydride heat storage system. Meanwhile, the running p-T is positively correlated, e.g., when the charging pressure is set at 0.2 MPa to 0.3 MPa, the well-matched T varies from 307 K to 317 K. When the discharging pressure is set at 0.4 MPa to 0.7 MPa, the well-matched T varies from 304 K to 320 K. For the metal hydride heat pump system, the optimal performance lies in maximizing the transported heat. Given the operating T, there exists a well-matched pressure range for the heat sink device, e.g., for the heat releasing process, when operating T is set at 353 K, 363 K, 373 K, 383 K and 393 K, the well-matched p are 2.3 MPa, 3.3 MPa, 3.8 MPa, 4.6 MPa and 6.1 MPa. Both the heat storage and heat pump performances are also affected by the operating pressure – temperature −transported heat, presenting improved region and degraded region. The optimal thermodynamic criterion and the matchability of the operating parameters provide a theoretical guidance for the MH-based thermodynamic system design and operation.

Enhancing hydrate-based natural gas storage capacity via optimal concentrations of epoxycyclopentane

With the growing demand for energy, natural gas has gained attention as a lower-emission option compared to the other conventional fossil fuels such as oil and coal. Consequently, there is significant interest in developing energy-efficient natural gas storage technologies. Gas hydrate-based storage offers a promising solution due to its relatively high capacity at moderate operating pressure and temperature conditions. Epoxycyclopentane (ECP) has emerged as an effective thermodynamic promoter, but its limited miscibility in water can influence storage capacity depending on its concentration. This study investigated the effect of varying ECP concentrations (4.0, 5.0, 5.6, 6.0, 6.5, and 7.0 mol%) on the gas storage capacity of hydrates formed from pure CH4 and a natural gas mixture (CH4 (90%) + C2H6 (7%) + C3H8 (3%)). We systematically examined thermodynamic stability, formation kinetics, crystalline structure, and guest distribution in ECP hydrates. The results revealed that ECP significantly promoted hydrate thermodynamic formation across all concentrations, with the optimal concentration for natural gas storage identified as 6.5 mol%, which achieved the highest gas storage capacity. Synchrotron XRD confirmed the formation of sII hydrates in both ECP + natural gas and ECP + CH4. Raman and 13C solid-state NMR analyses showed no CH4 occupancy in sII-L, which suggests the absence of pure natural gas hydrates. Cage occupancy estimation revealed that the highest CH4 occupancy in sII-S cages occurred at 6.5 mol% ECP, which contributed to an enhanced gas uptake. Time-dependent in-situ Raman and NMR analyses demonstrated that excess ECP can induce a two-step formation process, which further enhances storage capacity. Hence, we believe that these findings offer valuable insights into optimizing ECP concentration for the development of hydrate-based natural gas storage.

Numerical Simulation Study of Salt Cavern CO2 Storage in Power-to-Gas System

China’s renewable energy sector is experiencing rapid growth, yet its inherent intermittency is creating significant challenges for balancing power supply and demand. Power-to-gas (PtG) technology, which converts surplus electricity into combustible gas, offers a promising solution. Salt caverns, due to their favorable geological properties, are among the best choices for large-scale underground energy storage in PtG systems. CO2 leakage along the interlayer and salt rock–interlayer interfaces is a key constraint on the CO2 tightness of subsurface salt caverns. This paper focuses on the critical issue of tightness within salt cavern CO2 storage, particularly in the Jintan region. A coupled hydro-mechanics mathematical model is developed to investigate CO2 transportation and leakage in bedded salt caverns, with key variables such as permeability range, pore pressure evolution, and permeability changes being analyzed. The results reveal that permeability plays a decisive role in determining the CO2 transportation rate and leakage extent within the salt rock layer. Notably, the CO2 transportation rate and influence range in the mudstone interlayer are significantly larger than those in the salt rock over the same period. However, with prolonged storage time, the CO2 transportation rate and pressure increase in both salt rock and mudstone interlayer exhibit a decreasing trend, eventually stabilizing as the CO2 pressure front reaches the boundary of the simulation domain. Furthermore, elevated operating pressure markedly expands the permeability range and results in higher cumulative leakage. For a specific salt cavern, the CO2 leakage range can reach up to 142 m, and the leakage volume can reach 522.5 tonnes with the increase in operating pressure during 35 years of operation. Therefore, the setting of operational pressure should fully consider the influence of permeability and mechanical strength of the salt rock and mudstone interlayer. These findings provide valuable insights into optimizing the sealing performance of salt cavern CO2 storage systems under varying conditions.

Effect of different water quality on the performance of pressure compensating emitter in drip irrigation systems

AbstractPressure‐compensating emitters (PCE) ensure consistent flow rates and uniform irrigation in drip irrigation systems across varying pressures. However, the performance of PCE can be significantly compromised by marginal water, characterized by impurities like particulate matter, salt ions, microorganisms and organic substances. To date, research elucidating the factors contributing to PCE performance reduction with marginal water sources has been limited. This study investigated the effects of tour types of marginal waters on PCE performances, specifically saline water (rich in salt ions), high‐sediment water, biogas slurry (rich in organics) and reclaimed water (containing microorganisms), under three operational pressures (0.1 MPa, 0.2 MPa, 0.3 MPa). Variations in clogging substances and diaphragm performance within the PCE flow channel were analysed. Results indicated that PCE performance declined most rapidly in saline water, followed by high‐sediment water, biogas slurry and reclaimed water. Compared to clogging substances within the flow channel in reclaimed water conditions, those in biogas slurry, high‐sediment water and saline water increased by 3.4%, 17.5% and 93.1%, respectively. The flow coefficient decreased by 21.1%, 32.2% and 18.0%, respectively, while the flow index increased by 5.8%, 12.5% and 50.2%, respectively. Furthermore, the elastic modulus of the diaphragm decreased by 1.8%, 13.6% and 44.1%, respectively. These results underscored that chemical ions in the water source are the most critical factor influencing PCE performance, followed by sediment and organic matter, while microorganisms have a comparatively lesser impact. Furthermore, higher pressure levels were found to contribute to improvements in PCE performance. This study offers insights into the influence of various marginal waters on PCE performance, with implications for the broader adoption and implementation of pressure‐compensating drip irrigation technology in conditions involving marginal water.

“How could it be our responsibility?” The equity of Local Authority climate action in England

ABSTRACT The majority of English Local Authorities (LAs) have set targets to achieve net zero greenhouse gas emissions by 2050 or sooner, despite having no formal responsibilities to do so. However, it is questionable whether LAs are able to deliver these plans and targets whilst they are subject to significant operational pressures. This analysis applies the international “equity” framework of Common But Differentiated Responsibility and Respective Capabilities to the case of English LAs. The research evaluates responses from 28 semi-structured interviews with stakeholders from across levels of government, different sectors, and regions of England. We evaluate the drivers of inequalities in capabilities to implement climate action between LAs, and how these inequalities could be reduced through a number of governance interventions. Though the introduction of a statutory responsibility is frequently discussed in the literature, its perceived viability and equity have not been empirically assessed by stakeholders. We therefore evaluate stakeholder perspectives on whether this would be a fair mechanism for allocating responsibility to the local scale. We find that economic, social and political aspects of capability are interdependent, and that current governance arrangements tend to reinforce patterns of inequality in capability. We offer a series of policy recommendations to improve equity in burden-sharing between LAs, finding that funding reform and a well-designed and well-resourced statutory responsibility could be both effective and fair. Policy highlights The governance of local climate action in England reinforces existing inequalities in economic, social and political capability between Local Authorities (LAs). Though councils are currently taking action voluntarily, further support is required to ensure councils can equitably meet their net zero ambitions. A statutory responsibility would improve equity in burden-sharing for mitigation between councils, provided it was well-designed and resourced. A statutory responsibility could introduce a reporting component that would provide an evidence base to target greater support to councils that need it. Equity-based funding systems are proposed as a means of respecting the variable capabilities of different LAs.

BN O04 - Trends in the management of bile duct stones in the United Kingdom: Are we following the evidence?

Abstract Background Common bile duct stones (CBDS) are typically managed in two stages: Endoscopic Retrograde Cholangiopancreatography (ERCP) followed by laparoscopic cholecystectomy (LC). However, access to ERCP can be limited or require referral, has a high failure rate, often necessitates additional imaging, and may involve multiple procedures. Increasing evidence suggests that single-stage management, involving LC with intraoperative imaging and bile duct exploration when indicated, is cheaper, more effective, and reduces overall length of stay. British Society of Gastroenterology guidance states that it is a valid alternative to ERCP. This study aimed to determine whether clinical practice aligns with this evidence. Method National Health Service (NHS) Admitted Patient Care publications summarise Hospital Episode Statistics by financial year and are openly accessible. OPCS4 Procedure Codes were screened by two authors and categorised as “operative” or “endoscopic.” Codes detailing the management of CBDS or bile duct exploration were included, while ambiguous codes or those for non-stone indications were excluded. Data pertaining to these codes were extracted from the Admitted Patient Care publications for 2012 to 2022 and summarised in a Microsoft Excel spreadsheet. Trends were analysed using a Non-Seasonal Mann-Kendall Trend Test Results A total of 249,475 procedures for CBDS were performed over the ten-year period, with a mean patient age of 67. Annually, the total number of procedures increased from 21,365 to 27,668 (p=0.002). Endoscopic procedures increased from 19,716 to 25,976 (p=0.002), while operative procedures remained stable (1,649 to 1,692, p=0.431). Consequently, the proportion of endoscopic management rose from 92.3% to 93.9% (p<0.001). The mean age of patients undergoing operative procedures was ten years younger than those undergoing endoscopic procedures (57 vs. 67 years) Conclusion Despite evidence and guidance supporting single-stage procedures, there is a trend towards endoscopic management of CBDS in the UK. This may be due to operational pressures on the NHS, including the sequelae of the COVID-19 pandemic, or reflect challenges within hospital culture, skill mix, or equipment availability.

BN SO37 - Upper GI surgical training in the UK: Are there enough training opportunities? 10-year trends in Benign Upper GI index procedures and the impact of COVID-19

Abstract Background Surgical training was adversely impacted during the COVID pandemic, with reports of reduced logbook numbers and challenges in meeting training competencies. Despite a national elective care recovery plan, and interventions aimed at maintaining training opportunities, waiting list expansion has continued and has particularly impacted benign procedures. Upper GI trainees are all required to achieve “Level 4” (independent) competence in Cholecystectomy and Antireflux surgery, however there are anecdotally. fewer opportunities in the post-COVID era to train in these procedures. This study aimed to evaluate trends in these index procedures and to compare the pre- and post- COVID eras. Method The annual Admitted Patient Care (APC) publications draw on Hospital Episode Statistics and summarise activity for each financial year by OPCS4 codes. Codes pertaining to cholecystectomy and antireflux surgery (the “Benign Upper GI” competences on the Joint Committee of Surgical Training New Curriculum Checklist) were screened for inclusion. Data were extracted from APC publications between 2013 and 2023. These data were summarised in a Microsoft Excel Spreadsheet, categorised by index procedure and divided into pre-covid (2013-2019) and post-covid (2019-2023). Trends were evaluated using a Mann-Kendal Non-Seasonal Trend Test. Comparisons were undertaken using a two tailed unpaired t-test. Results Between 2013 and 2023 there was a statistically significant negative annual trend in the number of cholecystectomies from 75934 to 68182 (p=0.02), with a minimum of 47803 in the 2020-2021 financial year and a non-significant positive trend in the subsequent years. There were significantly fewer cholecystectomies in the 4 years following COVID (mean 77357 vs 63882, p=0.015). Antireflux procedures also underwent a significant negative trend from 5467 to 4745 (p=0.02), with a minimum of 2565 in the 2020-2021 financial year and a non-significant positive trend in subsequent years. Mean post-COVID antireflux procedures were also significantly lower (5548 vs 4256, p=0.03). Conclusion The procedures required for training in Benign Upper GI surgery in the UK are occurring with lower frequency than before the COVID pandemic. Whilst this may reflect ongoing operational pressures, or changes in clinical practice, this evidence suggests that training opportunities are now less frequent. This highlights the importance of focussed training and an awareness of training needs amongst both trainees and their mentors.

Evaluasi Unjuk Kerja Kompresor Screw SH250 di PT Pertamina EP Asset 4 CPP Gundih

The aim of this research is to analyze the performance of the SH250 Screw compressor based on field observation data. Based on the observation and data analysis, several conclusions can be drawn. First, the actual capacity of the compressor decreased by about 14.7485% from the design condition. This decrease is caused by the difference in operational pressure which is lower than the design pressure. Secondly, the power generated by the current compressor is about 136.143kW, which is lower than the design power of 250 kW. This decrease in power is due to the low input temperature. These findings indicate the importance of considering actual operational conditions in optimizing compressor performance. In this context, further adjustments or evaluations are recommended to ensure optimal performance of the SH250 Screw compressor. Factors such as operational pressure and input temperature should be carefully considered to achieve the expected results. This research provides valuable insights for the industry in understanding the factors affecting compressor performance and provides a basis for future performance improvements. These efforts are expected to improve operational efficiency and reduce potential losses in the use of the SH250 Screw compressor.

Numerical study on a new adjustable multi-hole throttling device for natural gas flooding

Natural gas flooding represents a significant technique for the enhancement of oil recovery, thereby facilitating the efficient utilization of oil and gas resources. In the injection and production system, the throttling gas nozzle is a key component that adjust the injection pressure according to the reservoir’s pressure. However, current throttling gas nozzles utilize a fixed structure, which presents a challenge in achieving online control of flow rate and pressure drop. Therefore, a new adjustable multi-hole throttling device was proposed in this paper, allowing for the regulation of pressure loss by changing the number of flowing holes. In order to gain insight into the operational principles and pressure drop characteristics of this new throttling device, the SST k-ω turbulence model and the NIST physical property model were employed to simulate the supercritical natural gas flow in the nozzle. The results demonstrate that there is an uneven distribution of velocity between the channels of the downhole multi-hole throttling device. The velocity in a single nozzle channel exhibits a trend of initially increasing rapidly and then decreasing, while the pressure exhibits an initial decrease, which is then followed by a slight increase. The pressure drops of the nozzle under different flow rates and flowing hole numbers were acquired, revealing that the pressure drop of the multi-hole throttling device is inversely proportional to the number of holes. The adjustment accuracy of pressure drop and flow rate is higher when the number of holes is between 4 and 6. However, a significant increase in pressure drop occurs when the number of holes is less than 3, resulting in poorer regulation accuracy. Furthermore, a pressure drop prediction model was developed based on the numerical results, which provides guidance for the application and design of the throttling device. In this study, a new natural gas flooding throttling device is proposed, offering a new approach for downhole equipment development. Additionally, this research provides guidance for the practical application and iterative improvement of this throttling device in future use.

Numercial modeling for enhanced heat transfer efficiency of spiral coils with supercritical fluid flow under different operating conditions

This research investigates the thermohydraulic performance and exergy destruction associated with the flow of supercritical carbon dioxide (sCO2) within spirally coiled mini tubes. The study examines the impact of different cross-sectional geometries. The primary objective of the study is to examine the impact of critical parameters, including shape, hydraulic diameter, inlet temperature, mass flux, and operating pressure, on important variables such as friction factor, heat transfer coefficient, and exergy efficiency. The computational simulation employs the RNG k−ε model. The Coupled algorithm was utilized for the determination of velocity and pressure fields, utilizing second-order discretization for domain partitioning and first-order discretization for other terms. The carbon dioxide (CO2) was conceptualized as a compressible gas with complex thermophysical attributes that are contingent upon variations in temperature and pressure. The thermophysical properties of carbon dioxide are evaluated within a defined range of operating conditions (298. 15 K < T < 455 K and 8 MPa < p < 10 MPa). The observed trends in HTC (heat transfer coefficient) demonstrate a correlation with specific heat, showing a peak at lower temperatures under increased operating pressures. Elevated operational pressure results in a reduction of the maximum HTC. The augmentation of mass flux results in an increase in heat transfer coefficient, thereby indicating an improvement in system efficiency. An augmentation in hydraulic diameter yields diminished heat transfer coefficients, mitigated pressure loss, and heightened exergy destruction.

Thermo-electric coupling dynamic modeling and response behavior analysis of PEMEC based on heat current method

Complete analysis of the dynamic characteristics of the proton exchange membrane electrolytic cell (PEMEC) is significant for its efficient and flexible utilization. To fully reflect the dynamic process including thermo-electric interactions within PEMEC, this paper disassembles this process and simplifies it for representation through a clear diagram of dynamic power flow. On this basis, we proposed a novel combined qualitative and quantitative analytical method for the comprehensive response by defining the evaluating indexes for PEMEC's response performance. Meanwhile, we analyzed the change pattern of dynamic response behavior, response time and the influence of thermo-electric interaction under multi-scenarios, like different voltage abrupt change magnitudes, different cathode operating pressures, and different inlet water temperatures. The results show that the PEMEC has the biggest response behavior with the longest response time under the largest external voltage variation magnitude. Besides, there is the shortest response time and smallest parameters total changes after response when the cathode operating pressure is 15bar Moreover, when the inlet water temperature is 40 °C it has the characteristic of quick action time and small response magnitude. The model, analysis method, and findings in this paper provide an effective reference for the operational regulation of PEMEC's thermal and electrical parameters.

Novel nanofiltration-reverse osmosis-high pressure nanofiltration membrane brine concentration (NF-RO-HPNF MBC) system for producing high purity high concentration sodium chloride brine from seawater

A pilot-scale study of a nanofiltration (NF) - reverse osmosis (RO) - membrane brine concentration (MBC) system was carried out using novel NF membranes for the NF and MBC systems. Two commercially available NF membranes with high magnesium rejection were tested for the removal of divalent ions from seawater. These membranes exhibited 81–87 % rejection of Ca and 95–97 % rejection of Mg at an 85 % recovery rate, resulting in a 4.3–5.3 times higher concentration of Ca and 5.4–6.7 times higher concentration of Mg in the NF reject than in the feed. Accordingly, the NF permeate had a high NaCl/TDS index of 96.7–97.8 %, facilitating the downstream production of high-purity NaCl salt. The potential of using NF membranes for brine concentration was investigated, and it was found that if a NF membrane could be operated at 75 bar, the NaCl solution could be concentrated to over 230 g/L. A pilot-scale trial was carried out on a 3-stage high pressure NF (HPNF) system, which achieved a concentration of 220 g/L from 78 g/L SWRO brine and 80 days of continuous operation. At a higher operating pressure, the system successfully concentrated the brine to 251 g/L as designed. The specific power consumption of the industrial 3-stage HPNF MBC system was estimated to be 111.0–123.3 kWh/t NaCl while concentrating from 75 g/L to 225 g/L and producing diluted steam at 43 g/L. This demonstrates competitiveness with conventional concentration methods such as thermal evaporation and electrodialysis.

3D-Printed Multi-Axis Alignment Airgap Dielectric Layer for Flexible Capacitive Pressure Sensor.

Flexible pressure sensors are increasingly recognized for their potential use in wearable electronic devices, attributed to their sensitivity and broad pressure response range. Introducing surface microstructures can notably enhance sensitivity; however, the pressure response range remains constrained by the limited volume of the compressible structure. To overcome this limitation, this study implements an aligned airgap structure fabricated using 3D printing technology. This structure, designed with a precisely aligned triaxial airgap configuration, offers high deformability under pressure, substantially broadening the pressure response range and improving sensitivity. This study analyzes the key structural parameters-the number of axes and pore size-that influence the compressibility and stability of the dielectric material. The results indicate that the capacitive pressure sensor with an aligned airgap structure, manufactured via 3D printing, exhibits a wide operating pressure range (50 Pa to 500 kPa), rapid response time (100 ms), wide limit of detection (50 Pa), and approximately 21 times enhancement in sensitivity (~0.019 kPa-1 within 100 kPa) compared with conventional bulk structures. Furthermore, foot pressure monitoring trials for wearable sensor applications demonstrated exceptional performance, indicating the sensor's suitability as a wearable device for detecting plantar pressure. These findings advocate for the potential of 3D printing technology to supplant traditional sensor manufacturing processes.

Performance prediction and enhancement strategy of a new proton exchange membrane fuel cell-hydrophilic modified tubular still hybrid system

The abundant low-grade waste heat generation in proton exchange membrane fuel cell (PEMFC) not only leads to energy wasting but also degrades the cell durability. Herein, an innovative hybrid system model that integrates PEMFC with a hydrophilic modified tubular still (HMTS) is developed, aiming to remove and harness the waste heat for extra freshwater production. Based on thermodynamic and electrochemical theories and considering major irreversible losses within the system, the model is formulated to obtain the performance metrics. Computational results demonstrate that the hybrid system outperforms the independent PEMFC, exhibiting a 13.26 % increase in maximum output power density, as well as significant improvements in energy efficiency (6.49 %) and exergy efficiency (23.36 %). Exhaustive parametric studies show that raising the fuel cell's operation temperature and operation pressure and the wind velocity, or reducing the thermodynamic losses positively enhances the overall output performance. Nevertheless, enlarging the proton exchange membrane thickness, tube shell diameter, or length of the tube shell worsens the output performance. Local sensitivity analyses identify that the thickness of proton exchange membrane is the most sensitive factor affecting the output performance. These results are helpful for optimally designing and running a high-efficient system.

Optimization of Rotational Hydrodynamic Cavitation Reactor Geometry

A Rotary-Pulsation Apparatus (RPA), also known in the literature as a Rotational Hydrodynamic Cavitation Reactor (RHCR), is a device which typically consists of a rotating mechanism that generates pulsations or vibrations within a fluid. This can be achieved through various means such as mechanical agitation, pneumatic pulses, or hydraulic forces. It is widely used in food, chemical, pharmaceutical, and microbiological industries to improve the mixing of different fluids, dispersion, pasteurization, and sterilization. In the present paper, a CFD study was conducted to develop and optimize the geometry of the RPA’s rotor and stator to induce cavitation in the fluid flow. The effect of cavitation has the potential to improve dispersion and emulsion properties and to significantly reduce operation pressure, in comparison to conventional mixing systems.

Application of chaotic teaching-learning-based optimization technique for estimating unknown parameters of proton exchange membrane fuel cell model.

Proton exchange membrane fuel cells (PEMFC) possess features like high specific power density, low operating temperature, and low operating pressure and thus are most widely used. The performance of PEMFC highly depends on its output voltage which further affects its efficiency. This research paper aims to improve this output voltage by minimizing the losses through parameter estimation technique for three well-known commercial PEMFC stacks, namely, 250W, BCS 500W, and Ballard Mark V. The multiobjective function framed for optimization serves two goals. One is to extract the unknown parameters of FC, and second is to achieve the minimum sum of squared errors (SSE) that occur due to the difference between experimental voltage and estimated voltage. Chaotic teaching-learning-based optimization (CTLBO) algorithm is used for optimization process. SSE values obtained for three commercial PEMFC stacks 250W, BCS 500W, and Ballard Mark V are 7.02267, 4.00150, and 0.8100, respectively. The applicability of this technique is further checked for different operating conditions of each model. The I-P (current-power) curve and I-V (current-voltage) curve obtained using estimated data closely matched the experimental data that showed the practical relevance and efficacy of the algorithm. A comparison is done among the SSE results obtained using CTLBO to other competitive algorithms mentioned in the literature. CTLBO showed its superiority over other algorithms in estimating the unknown parameters of PEMFC stack parameters.

Two-stage scheduling of apron support vehicles considering multi-vehicle coordination

Large airport apron support vehicles have always been facing great operating pressure, and the coordination constraints of various apron support services and dynamic flight information pose higher challenges to vehicle scheduling. Considering the differences in vehicle operation constraints in three different modes: continuous work, continuous work with capacity constraints, and round-trip work, a multi-vehicle coordinated apron support vehicle scheduling model is established with the goal of minimizing the number of vehicles and the total driving distance. According to the actual operation of the airport, the model is solved in two stages. In the static stage, an NSGA II algorithm integrating local search is designed, and in the dynamic stage, a neighborhood search algorithm is designed to solve the multi-vehicle coordinated scheduling problem. Data simulation results show that compared with first-come-first-served, the number of vehicles and the total driving distance in the static scheduling stage are reduced by 18.9%and respectively 8.9%; the dynamic scheduling stage results can maintain the number of vehicles in the original scheduling plan, and the adjustment of driving distance is reduced compared with the large-scale neighborhood search algorithm 25.8% . The research results can provide certain guiding significance for the scheduling management and decision-making of apron support vehicles in large airports.