Safe Operating Conditions Research Articles

Blood trauma in veno-venous extracorporeal membrane oxygenation: low pump pressures and low circuit resistance matter

BackgroundVeno-venous extracorporeal membrane oxygenation (VV ECMO) has become standard of care in patients with the most severe forms of acute respiratory distress syndrome. However, hemolysis and bleeding are one of the most frequent side effects, affecting mortality. Despite the widespread use of VV ECMO, current protocols lack detailed, in-vivo data-based recommendations for safe ECMO pump operating conditions. This study aims to comprehensively analyze the impact of VV ECMO pump operating conditions on hemolysis by combining in-silico modeling and clinical data analysis.MethodsWe combined data from 580 patients treated with VV ECMO in conjunction with numerical predictions of hemolysis using computational fluid dynamics and reduced order modeling of the Rotaflow (Getinge) and DP3 (Xenios) pumps. Blood trauma parameters across 94,779 pump operating points were associated with numerical predictions of shear induced hemolysis.ResultsMinimal hemolysis was observed at low pump pressures and low circuit resistance across all flow rates, whereas high pump pressures and circuit resistance consistently precipitated substantial hemolysis, irrespective of flow rate. However, the lower the flow rate, the more pronounced the influence of circuit resistance on hemolysis became. Numerical models validated against clinical data demonstrated a strong association (Spearman’s r = 0.8) between simulated and observed hemolysis, irrespective of the pump type.ConclusionsIntegrating in-silico predictions with clinical data provided a novel approach in understanding and potentially reducing blood trauma in VV ECMO. This study further demonstrated that a key factor in lowering side effects of ECMO support is the maintenance of low circuit resistance, including oxygenators with the lowest possible resistance, the shortest feasible circuit tubing, and cannulae with an optimal diameter.

Decision-making method of managed pressure drilling based on real-time calculation and analysis models

Abstract As petroleum exploration and development extend towards marginal, deep, and unconventional resources, drilling challenges such as narrow density windows and high wellbore control risks become increasingly prominent. Managed pressure drilling (MPD) proves effective in reducing drilling operational difficulties and well control risks in narrow safe-density window formations. However, existing MPD systems have limited capabilities for real-time calculation and analysis in the absence of downhole pressure measurement data, hindering accurate guidance for real-time calculation, analysis, and control decision recommendations in both conventional and precise MPD operations.Therefore, based on on-site engineering logging, real-time data from MPD operations, a branch decision tree was established to automatically determine the operational conditions of MPD. This achieved real-time identification of 11 drilling conditions. Starting from the characteristics of two-phase fluid flow in the annulus, coupling wellbore pressure and formation fluid invasion, a predictive model for annular pressure distribution during MPD was established. This model facilitated the calculation, determination, and recommendation of the pre-control value for wellhead backpressure. Building upon theoretical research, a MPD calculation, analysis, and control decision system was developed. Field testing and validation indicated that the system could simulate and analyze wellbore pressure and wellhead backpressure values, automatically identify drilling conditions and downhole complexities. The average error between the calculated and measured values of the standpipe pressure was 1.88%. The accuracy of the predicted wellhead backpressure values based on safe operating conditions compared to the actual controlled values reached 89.8%. This system achieved real-time calculation, analysis, and control decision-making based on real-time engineering parameters, enhancing the reliability and timeliness of wellhead backpressure control in MPD operations. It effectively guided conventional MPD operations and improved the capabilities and intelligence level of precision MPD operations after process optimization.

Experiments and modeling of solid oxide co-electrolysis: Occurrence of CO2 electrolysis and safe operating conditions

Solid Oxide Electrolysis Cell (SOEC) has attracted considerable attention for its potential scalability and high energy conversion efficiency. It is capable of electrolyzing both H2O and CO2 simultaneously, generating syngas that can be further synthesized into carbon-based fuels, which are good energy carriers for long-term energy storage. However, despite its promise, the understanding of the reaction mechanism crucial for extending cell longevity remains incomplete, and concerns persist regarding carbon deposition during co-electrolysis. A dual approach, combining experiments and Multiphysics simulations was adopted to explore the reaction mechanism and carbon deposition risk across a wide range of operating conditions on industrial-size cells. Both experimental observations and simulation results indicate that CO2 electrolysis and carbon deposition are significantly influenced by the inlet water content and flow rates at the fuel electrode. Increasing the inlet H2O concentration and fuel electrode flow rates lead to CO2 electrolysis occurring at higher current densities. Also, carbon deposition, which was found at the interface of fuel electrode and electrolyte, can be mitigated by controlling the conversion rate relative to the inlet H2O content and by increasing the flow rate at the fuel electrode. Additionally, the current density distribution of H2O electrolysis and CO2 electrolysis across the cell were also investigated. The obtained insights hold significance for the practical operation of SOEC co-electrolysis.

Investigation of safe operating conditions for reducing acid corrosion and ABS deposition in rotary air preheater using computational fluid dynamics

Investigation of safe operating conditions for reducing acid corrosion and ABS deposition in rotary air preheater using computational fluid dynamics

Evaluating the thermal stability of chemicals and systems: A review

AbstractIn the realm of chemical processing, particularly at the industrial scale, safety is of utmost importance. A predominant factor causing accidents within the chemical industry is runaway phenomena, primarily initiated by uncontrolled exothermic reactions. This review critically examines the often‐overlooked decomposition mechanisms as a significant contributor to thermal energy release, necessitating a comprehensive revision and understanding of both experimental and theoretical strategies for assessing thermal degradation. Key to this discourse is the explication of calorimetry as the principal experimental technique, alongside ab initio quantum chemistry simulations as a robust theoretical framework for quantifying the most relevant properties. However, more than mere cognisance of these methodologies is required for a meticulous thermal stability assessment. The review emphasizes identifying and quantifying fundamental parameters through experimental and theoretical investigations. Only upon acquiring these parameters, including kinetic, thermodynamic, onset, and peak characteristics of the exothermic decomposition reactions, can one effectively mitigate risks and hazards in designing and optimizing chemical processes and apparatus. Furthermore, this review delineates qualitative and quantitative methodologies for hazard assessment, proffering strategies for estimating safe operational conditions and sizing relief devices. The paper culminates in exploring future trajectories in thermal stability assessments, focusing on emerging applications in lithium‐ion batteries, electrolyzers, electrified reactors, ionic liquids, artificial intelligence and machine learning approaches. Thus, the paper underlines the evolving landscape of thermal risk management in contemporary and future chemical industries.

Continuous mapping of nuclear reactor core power using artificial neural network even in the presence of inactive detectors

Monitoring the radial power distribution during the operation of a pressurized light water reactor (PWR) is crucial for ensuring safe operating conditions and achieving high levels of fuel burnup. This paper introduces a methodology utilizing Artificial Neural Networks (ANN) for reconstructing the radial power distribution in the core of a Pressurized Water Reactor (PWR) with a hot full power of 1876 MWth, such as the Angra 1 reactor. This approach uses measurements from Self-Powered Neutron Detectors (SPND), simulated through the SERPENT code. The use of ANN demonstrated good accuracy in predicting the radial power distribution with an average relative error of 1.27%, considering 36 active detectors, with maximum relative error of 6.99%. Moreover, the proposed process demonstrated robust performance, even when measurements from one, two, or three SPND detectors were unavailable, resulting in errors of 1.24%, 1.13 %, and 1.09%, respectively. Therefore, the methodology ensures a reliable reconstruction of the radial power distribution, even when SPND detector measurements are unavailable, enabling the optimization of detector use and contributing to the increase of operational safety margins.

Towards the development of a safe, metal-catalyzed aerobic oxidation of 2-acetyl thiophene

Thiophene-2-carbonyl chloride (TCC) is a key raw material in the manufacture of active ingredients for agriculture. A new 3-step process for preparing TCC from commercial thiophene was recently developed that featured a metal-catalyzed aerobic oxidation of 2-acetylthiopehene (AcT). That process utilized pure oxygen in a flammable solvent, acetic acid, at elevated temperatures, which represented a hazardous condition by operating above the limiting oxygen concentration for the solvent and at a temperature above the flashpoint for the solvent. More recently, the same oxidation reaction has been achieved in an autoclave using diluted oxygen. Described in this Letter are details of our progress towards the identification of safe operating conditions for the aerobic oxidation of AcT.

Enhancing cellular behavior in repaired tissue via silk fibroin-integrated triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) have emerged as a promising approach for generating electricity and providing electrical stimuli in medical electronic devices. Despite their potential benefits, the clinical implementation of TENGs faces challenges such as skin compliance and a lack of comprehensive assessment regarding their biosafety and efficacy. Therefore, further research is imperative to overcome these limitations and unlock the full potential of TENGs in various biomedical applications. In this study, we present a flexible silk fibroin-based triboelectric nanogenerator (SFB-TENG) that features an on-skin substrate and is characterized by excellent skin compliance and air/water permeability. The range of electrical output generated by the SFB-TENG was shown to facilitate the migration and proliferation of Hy926, NIH-3T3 and RSC96 cells. However, apoptosis of fibroblast NIH-3T3 cells was observed when the output voltage increased to more than 20 V at a frequency of 2 Hz. In addition, the moderate electrical stimulation provided by the SFB-TENG promoted the cell proliferation cycle in Hy926 cells. This research highlights the efficacy of a TENG system featuring a flexible and skin-friendly design, as well as its safe operating conditions for use in biomedical applications. These findings position TENGs as highly promising candidates for practical applications in the field of tissue regeneration.

Safe Operating Conditions of isoperiodic Homogeneous Semi-Batch Reaction Based on Parameter Uncertainties Analysis

Proper operating conditions have a significant impact on the process state of semi-batch reaction. However, various error and bias lead to the uncertainties of parameter, which affect process safety of the semi-batch reaction. In this work, the effect of dimensionless parameters dimensionless adiabatic temperature rise (), Westerterp number (Wt), , dimensionless activation energy (γ), volumetric heat capacity ratio (RH) and relative volume increase (ε) on the temperature of the isoperiodic homogeneous semi-batch reaction are investigated by local sensitivity analysis. The sensitivity of the dimensionless maximum temperature to global parameters is analyzed using the scatter plot method based on Monte-Carlo sampling. Parameter sensitivity results are further quantitatively calculated by the eFAST method. The results indicate that there is a strong linear relationship between the maximum reaction temperature and △τad,0, which exhibits the highest sensitivity index compared to the other parameters. The safety boundary diagram and adiabatic temperature diagram are constructed by considering parameter uncertainty and the effect of parameter uncertainty on the critical criteria is analyzed.

An Experimental Phototherapy Device for Studying the Effects of Blue Light on Patients with Raynaud's Phenomenon.

Raynaud's phenomenon (RP) is a condition that causes decreased blood flow to areas perfused by small blood vessels (e.g., fingers, toes). In severe cases, ulceration, gangrene, and loss of fingers may occur. Most treatments focus on inducing vasorelaxation in affected areas by the way of pharmaceuticals. Recently, animal studies have shown that vasorelaxation can be induced by non-coherent blue light (wavelength ~ 430-460nm) through the actions of melanopsin, a photoreceptive opsin protein encoded by the OPN4 gene. To study this effect in humans, a reliable phototherapy device (PTD) is needed. We outline the construction of a PTD to be used in studying blue light effects on Raynaud's patients. Our design addresses user safety, calibration, electromagnetic compatibility/interference (EMC/EMI), and techniques for measuring physiological responses (temperature sensors, laser Doppler flow sensors, infrared thermal imaging of the hands). We tested our device to ensure (1) safe operating conditions, (2) predictable, user-controlled irradiance output levels, (3) an ability for measuring physiological responses, and (4) features necessary to enable a double-blinded crossover study for a clinical trial. We also include in the Methods an approved research protocol utilizing our device that may serve as a starting point for clinical study. We introduced a reliable PTD for studying the effects of blue light therapy for patients suffering from Raynaud's phenomenon and showed that our device is safe and reliable and includes the required measurement vectors for tracking treatment effects throughout the duration of a clinical study.

Operability analysis and line failure risk assessment for a tanker moored at berth

Oil terminals are critical infrastructures for the safe transfer of oil between ships and facilities on land. However, the presence of waves can pose a substantial risk to the mooring system, particularly when dealing with period waves that exceed 8 s. To better understand this relationship and minimize potential risks such as displacement and line failure, physical model tests were conducted. These tests sought to analyse how waves interact with the mooring system, which consists of ships, lines, and fenders. The findings of the research indicate that under experimental conditions, the ship's ability to operate safely is largely determined by its sway and roll motion. Among the various lines in the mooring system, the force exerted on the breast lines was found to be the highest, making them more susceptible to failure. This highlights the importance of paying close attention to these specific lines during operations, and considering necessary adjustments to ensure safety. Furthermore, the study also evaluated the maximum allowable operating wave height of the ship, taking into consideration the limitations imposed by movement and mooring force. These test results can serve as a valuable reference for determining the safe operating conditions for ships in oil terminals, contributing to improved mooring safety. Lastly, the study also took into account the potential occurrence of mooring failure. The event of one breast-fore line failure (Case1) and two breast-fore lines failure (Case2) were both tested. The results showed that the most significant impact was on the adjacent headlines, which increased approximately 40% and 70% respectively. Furthermore, it is important to recognize that the failure of one line may trigger a cascade effect, leading to the gradual failure of other lines and significantly jeopardizing mooring safety.

Battery Energy Storage Systems: A Review of Energy Management Systems and Health Metrics

With increasing concerns about climate change, there is a transition from high-carbon-emitting fuels to green energy resources in various applications including household, commercial, transportation, and electric grid applications. Even though renewable energy resources are receiving traction for being carbon-neutral, their availability is intermittent. To address this issue to achieve extensive application, the integration of energy storage systems in conjunction with these resources is becoming a recommended practice. Additionally, in the transportation sector, the increased demand for EVs requires the development of energy storage systems that can deliver energy for rigorous driving cycles, with lithium-ion-based batteries emerging as the superior choice for energy storage due to their high power and energy densities, length of their life cycle, low self-discharge rates, and reasonable cost. As a result, battery energy storage systems (BESSs) are becoming a primary energy storage system. The high-performance demand on these BESS can have severe negative effects on their internal operations such as heating and catching on fire when operating in overcharge or undercharge states. Reduced efficiency and poor charge storage result in the battery operating at higher temperatures. To mitigate early battery degradation, battery management systems (BMSs) have been devised to enhance battery life and ensure normal operation under safe operating conditions. Some BMSs are capable of determining precise state estimations to ensure safe battery operation and reduce hazards. Precise estimation of battery health is computed by evaluating several metrics and is a central factor in effective battery management systems. In this scenario, the accurate estimation of the health indicators (HIs) of the battery becomes even more important within the framework of a BMS. This paper provides a comprehensive review and discussion of battery management systems and different health indicators for BESSs, with suitable classification based on key characteristics.

Controlling the structural features of tin dioxide nanoparticles embedded reduced graphene oxide on carbon cloth to serve as high stability fast charging anode for Li-ion cells

Tin dioxide or stannic oxide (SnO2) is an n-type semiconductor that has profound applications in gas sensors, solar cells, and energy storage devices like Li-ion batteries. Due to their high theoretical capacity (1494 mAh g−1) affordability, eco-friendliness, and safe operating conditions, SnO2 based anode materials are being extensively studied. Electrochemical capacity and stability for energy storage can be enhanced by embedding facet exposed SnO2 nanoparticles in reduced graphene oxide (rGO). In this study, SnO2 nanoparticles are synthesized and incorporated into rGO network via a simple solvo-thermal method is applied onto a carbon cloth substrate and used as anode for SnO2/rGO based Li-ion cell. The initial discharge capacity is found to be 1415 mAh g−1 and the charge capacity to be 1236 mAh g−1 with an initial Coulombic efficiency of 87 % at a current rate of 0.1 A g−1. The cell also exhibits excellent cycling stability and rate capability, with a discharge capacity of 1034 mAh g−1 and a charge capacity of 998 mAh g−1 at a current rate of 0.3 A g−1. This electrode is stable at a higher current rate of 2C (3 A g−1) and hence offers high prospects as anode material for application in fast-charging rechargeable cells.

Multi-Functional and Flexible Nano-Silver@MXene Heterostructure-Decorated Graphite Felt for Wearable Thermal Therapy.

Wearable heaters with multifunctional performances are urgently required for the future personal health management. However, it is still challengeable to fabricate multifunctional wearable heaters simultaneously with flexibility, air-permeability, Joule heating performance, electromagnetic shielding property, and anti-bacterial ability. Herein, silver nanoparticles (AgNPs)@MXene heterostructure-decorated graphite felts are fabricated by introducing MXene nanosheets onto the graphite felts via a simple dip-coating method and followed by a facile in situ growth approach to grow AgNPs on MXene layers. The obtained AgNPs@MXene heterostructure decorated graphite felts not only maintain the intrinsic flexibility, air-permeability and comfort characteristics of the matrixes, but also present excellent Joule heating performance including wide temperature range (30-128 °C), safe operating conditions (0.9-2.7V), and rapid thermal response (reaching 128 °C within 100 s at 2.7V). Besides, the multifunctional graphite felts exhibit excellent electromagnetic shielding effectiveness (53dB) and outstanding anti-bacterial performances (>95% anti-bacterial rate toward Bacillus subtilis, Escherichia coli and Staphy-lococcus aureus). This work sheds light on a novel avenue to fabricate multifunctional wearable heaters for personal healthcare and personal thermal management.

Neutronic examination of the U–Mo accident tolerant fuel for VVER-1200 reactors

In this study, we investigated the possibility of employing accident tolerant fuel (ATF) in VVER-1200/V491 assembly without gadolinium-containing fuel rods using the Monte Carlo code Serpent 1.1.7 with ENDF/B-VII cross-section library. The analysis involves assembly design with reflective boundary conditions. To compare the neutronic performances, U–5Mo, U-7.5Mo, U–10Mo, and U–15Mo fuels were chosen in addition to ordinary UO2 fuel. The concentration of 135Xe, 149Sm, fissile and fertile isotopes with burnup, reactivity feedback with fuel temperature variation, and βeff values were calculated. The results indicate that the fuel cycle length increases by 54.27% for U–5Mo, 32.6% for U-7.5Mo, and 13.8% for U–10Mo, while it decreases by 16.4% for U–15Mo fuel. Additionally, the effect of 95Mo content in natural Mo was investigated by reducing the 95Mo concentration. According to the results, each proposed fuel's fuel cycle length extended when the depletion ratio of 95Mo increased. Additionally, the calculations for reactivity feedback guarantee safe operating conditions for all U-xMo fuels.

Local-Stability Analysis of Cascaded Control for a Switching Power Converter

Switching power converters are integral in various applications like transportation and renewable energy. After their design, ensuring stable closed-loop poles is critical to maintain safe operating conditions. This study focuses on a switching DC-DC boost converter with a cascade control approach using an energy controller for the outer loop and indirect-sliding mode control for the inner loop. The research objective involves investigating stability through eigenvalue evaluation at different operating points. A large-signal average model is applied to make controlled performance independent of the operating point by fixing system poles. Nonlinear controllers, specifically indirect-sliding mode control, are chosen for their robustness, constant switching frequency, and implementation ease. Results indicate that insufficient decoupling leads to eigenvalue displacement, impacting control parameter choices. The research contribution is investigating the local stability of cascaded control, considering its advantageous implications for both performance and design. This study contributes to the understanding of switching power converters' stability, emphasizing the proposed methodology's broader applicability to diverse converter structures. The proposed approach, applicable to various switching power converters, sheds light on the importance of proper decoupling between outer and inner loop dynamics.

Limitations in the electrochemical analysis of voltage transients.

Objective. Chronopotentiometric voltage transients (VTs) are used to assess the performance of bionic electrodes. The data obtained from VTs are used to define the safe operating conditions of clinical devices. Various approaches to analysing VTs have been reported, and a number of limitations in the accuracy of the measurements in relation to electrode size have been noted previously.Approach. The impact of electronic hardware and electrode configuration on VTs is discussed.Main results. The slew rate, rise time, sample time, minimum pulse length and waveform averaging characteristics of the electronic hardware, and electrode configuration will impact on VT measurement accuracy. Subsequently, activation and polarisation voltage measurements, and the definition of safe stimulation levels can be affected by the electronic hardware and electrode configuration.Significance. This article has identified some limitations in the previous literature related to the measurement and reporting of VTs and subsequent analysis of access and polarisation voltages. Furthermore, the commonly used Shannon plot used to define safe stimulation protocols does not correct for uncompensated resistance, account for electrode roughness or changes in electrode configuration. The creation of a safe stimulation plot which has been corrected for uncompensated resistance would generate more widely applicable stimulation guidelines for clinical devices used in different anatomical locations such as endovascular neural interfaces.

Investigating the influence of operating variables on sealing performance of a V-ring seal stack in the oil and gas industry for enhanced environmental and operational performance

Static V-ring seals, essential components in oil and gas industry valves, have received limited attention compared to rotary and reciprocating seals in previous research. This study fills this gap by meticulously investigating the performance of these seals under conditions involving minimal or no rotational movement, offering valuable insights into their functional capabilities. The objectives of this experimental study are to develop an experimental setup mirroring industrial conditions to assess the performance of seals used in oil and gas valves. Accordingly, two fluorinated elastomer seals (AFLAS) and three Polytetrafluoroethylene (PTFE) seals were employed together as a single seal stack to understand the leakage behavior as well as the range of safe operating conditions under delayed gas leakage. The operating conditions for the experiments have been adopted to simulate drilling rigs. Hence, temperatures ranging from room temperature to 394.15 K and 477.15 K, diverse pressures from 4.14 MPa to 68.95 MPa, and variable motion speeds (0 RPM, 2 RPM, and 10 RPM) were incorporated in the experiments. The study revealed a positive correlation between leakage rate with both pressure and dynamic motion, reflecting valve opening and closing actions. In contrast, a negative correlation was noted between leakage rate and temperature in both static and dynamic conditions. At 68.95 MPa, the highest observed leak rate was 2.96 × 10−4 mol/s at room temperature, nearly ninety-five times higher than the rate recorded at 4.14 MPa (3.08 × 10−6 mol/s). Also, at an elevated temperature of 477.15 K, the leak rate significantly decreased to 1.08 × 10−5 mol/s, approximately twenty-six times lower than the room temperature rate. Furthermore, the study revealed that the influence of motion on leak rate diminished significantly at high temperatures compared to low temperatures, indicating a complex interplay between motion, temperature, and leakage behavior in the tested seals. Additionally, this investigation encompasses a thorough imaging analysis of the seals, aimed at assessing structural changes and the overall seal condition under varying operational circumstances. This research promises to guide customized sealing material development, enhancing safety and environmental performance in the oil and gas sector, making a valuable contribution to the industry.

Core design: Review & perspectives in Spain

In Core Fuel Management (ICFM) is an essential part of the operation of all commercial nuclear reactors. At the beginning of each fuel cycle (BOC), an optimal loading pattern is required to produce safe and economical operating conditions, such as uniform power distribution and a high degree of fuel burnup. These operating conditions are sought to achieve maximum useful life at minimum cost and the highest levels of safety, which leads to maximization of benefits. This article describes the work done by Spanish nuclear related organizations, which are currently involved in core design and core analyses from industrial, research and safety perspectives. In many instances, achieving enhanced accident tolerance would provide significant opportunities for outstanding research and improvements in operational cost benefits for the industry.

경찰의 초동대응 체계 개선을 위한 드론 활용 방안 연구

This study explores the necessity and potential of utilizing drone technology in police operations. To address the increasing crime rates and complex safety issues in modern society, the efficient allocation of police resources and swift response are becoming imperative. This research analyzes how drone technology can meet these demands and how AI can enhance the operation of drones from both theoretical and practical perspectives. The use of drones in first response scenarios can reduce arrival times at scenes, enable monitoring over extensive areas, and facilitate accurate situation awareness, thus supporting the police in taking quicker and more effective measures. However, the integration of such technologies necessitates consideration of the legal and ethical issues that may arise, as well as preventive measures against potential technological errors and privacy invasions. The study underscores the need for a legal basis, procedural legitimacy, and safe operational conditions when actively utilizing drones and AI technology in police activities, and presents specific recommendations for this purpose.