Safety Guidance Research Articles

Mining and analysis of adverse events profile of Guanfacine using FDA Adverse Event Reporting System (FAERS) database

ABSTRACT Objective This study aims to evaluate the Guanfacine-associated adverse events (AEs) in real-world using data mining in FAERS database, seeking to provide safety profile and guidance for the potential therapeutic practices. Methods We retrospectively extracted Guanfacine-associated AEs reports in the FAERS database from the first quarter of 2004 (Q1) to the fourth quarter of 2023 (Q4). All data were strictly collected and comprehensively analyzed. Disproportionality analyses, including the reporting odds ratio (ROR), the proportional reporting ratio (PRR), the Bayesian confidence propagation neural network (BCPNN), and the empirical Bayesian geometric mean (EBGM). Results Out of 16,985,532 reports collected from the FAERS database, 2,709 reports of Guanfacine as the ‘primary suspected (PS)’ and 8,464 AEs induced by Guanfacine were identified. Most AEs reports (67.45%) occurred within the first 30 days of treatment (excluding unreported or unknown onset time reports). A total of 158 significant PTs that meet all four algorithms were detected. Known neuropsychiatric events and cardiovascular events documented in the drug’s leaflet were found. Besides, unexpected significant AEs such as homicidal ideation, self-injurious ideation, growth failure, excessive eye blinking were also found. Conclusion Our study has unveiled novel Guanfacine-associated AEs signals and might provide guidance for its rational use.

Peran Media Sosial X Dalam Pemanfaatan Upaya Mitigasi Bencana

Social media has become a strategic tool in supporting disaster mitigation efforts, including in the rapid and widespread dissemination of information. This study analyzes the role of social media X (formerly Twitter) in supporting disaster mitigation efforts for the eruption of Mount Lewotobi Laki-laki on November 8, 2024. This mountain erupted twice with the eruption column reaching 10 km above the peak, producing thick volcanic ash that affected the surrounding area. The National Disaster Management Agency (BNPB) utilized social media X to provide the latest information, early warnings, and safety guidance to the public. The research method used a descriptive-qualitative approach with content analysis of BNPB's official posts on the X platform. The results showed that social media X was effective in disseminating real-time information, raising public awareness, and coordinating emergency response efforts. In less than an hour after the first eruption, BNPB managed to reach thousands of users with information related to the affected areas, evacuation steps, and health recommendations related to volcanic ash. However, there are challenges such as the potential for the spread of false information that can cause panic in the community. This study confirms that social media X has an important role in disaster risk management. Optimal use of social media, supported by organized information management, can help save lives and minimize the impact of disasters. This study recommends intensive training for BNPB officers in utilizing social media effectively for disaster mitigation.

Study on Soil Freeze–Thaw and Surface Deformation Patterns in the Qilian Mountains Alpine Permafrost Region Using SBAS-InSAR Technique

The Qilian Mountains, located on the northeastern edge of the Qinghai–Tibet Plateau, are characterized by unique high-altitude and cold-climate terrain, where permafrost and seasonally frozen ground are extensively distributed. In recent years, with global warming and increasing precipitation on the Qinghai–Tibet Plateau, permafrost degradation has become severe, further exacerbating the fragility of the ecological environment. Therefore, timely research on surface deformation and the freeze–thaw patterns of alpine permafrost in the Qilian Mountains is imperative. This study employs Sentinel-1A SAR data and the SBAS-InSAR technique to monitor surface deformation in the alpine permafrost regions of the Qilian Mountains from 2017 to 2023. A method for spatiotemporal interpolation of ascending and descending orbit results is proposed to calculate two-dimensional surface deformation fields further. Moreover, by constructing a dynamic periodic deformation model, the study more accurately summarizes the regular changes in permafrost freeze–thaw and the trends in seasonal deformation amplitudes. The results indicate that the surface deformation time series in both vertical and east–west directions obtained using this method show significant improvements in accuracy over the initial data, allowing for a more precise reflection of the dynamic processes of surface deformation in the study area. Subsidence is predominant in permafrost areas, while uplift mainly occurs in seasonally frozen ground areas near lakes and streams. The average vertical deformation rate is 1.56 mm/a, with seasonal amplitudes reaching 35 mm. Topographical (elevation; slope gradient; aspect) and climatic factors (temperature; soil moisture; precipitation) play key roles in deformation patterns. The deformation of permafrost follows five distinct phases: summer thawing; warm-season stability; frost heave; winter cooling; and spring thawing. This study enhances our understanding of permafrost deformation characteristics in high-latitude and high-altitude regions, providing a reference for preventing geological disasters in the Qinghai–Tibet Plateau area and offering theoretical guidance for regional ecological environmental protection and infrastructure safety.

An Adaptive Ensemble Approach Using Online Global and Local Models for Pump Pressure Prediction in Well Cementing Operations

Summary In cementing operations, conventional methods for predicting wellhead pump pressure, which rely on empirical and numerical models, often fall short regarding real-time accuracy and adaptability to different geological blocks and cementing techniques. These shortcomings hinder precise control of the wellhead pressure range, impacting operational safety, efficiency, and on-site personnel guidance. Furthermore, traditional offline machine-learning models cannot handle concept drift due to changing downhole fluid conditions during cementing. This paper frames wellhead pump pressure prediction as an online regression forecasting problem that utilizes the strengths of incremental and online ensemble learning with the Hoeffding tree regressor to overcome these challenges. First, data features are partitioned into subsets to create base learners, and then global and local models are deployed to address concept drift. The dynamic integration of these models significantly improves adaptability and performance. Experimental results confirm the superiority of our method over existing approaches. Compared with the suboptimal online models, mean squared error (MSE) is reduced for pump pressure prediction in five cementing data sets by 74.65%, 75.09%, 59.27%, 65.21%, and 70.01%, respectively. Additionally, MSE is reduced by 52.46%, 51.18%, 42.93%, 57.12%, 56.23%, 64.83%, and 79.51%, respectively, in seven open data sets, which showcases the broad applicability of our method to other regression tasks.

Transverse-Direction Post-Seismic Running Safety of Longitudinally Connected Ballastless Track–Continuous Girder Bridge Systems Considering Earthquake Damage State

The transverse-direction post-seismic running safety of a longitudinally connected ballastless track-continuous girder bridge (LCBTCGB) system considering earthquake damage state (EDS) was studied. In this study, a simulation model of an LCBTCGB was established, and the post-earthquake damage law of the LCBTCGB was analyzed by selecting the ground motion that had the greatest influence from within the existing studies. The EDS of key interlayer components and the residual deformation law of each layer structure of the LCBTCGB system were defined. Subsequently, the residual deformations and EDS from the simulation model were imported into a coupled dynamic model of the train, track, and bridge. Evaluation of running safety evaluation after an earthquake was carried out with and without considering EDS, and a running safety guidance diagram for after an earthquake is provided. The results revealed that under conditions of rare earthquakes, without considering EDS, the running safety judgment after the earthquake were underestimated, and the risk increased by 13.6%. Following the designed earthquake, the running safety risk after the earthquake increased by 18.7% if EDS was not considered. The risk of the running safety index exceeding the limit did not increase linearly with earthquake intensity with and without considering EDS. When the EDS was considered, derailment coefficients and wheel axle lateral forces exceeded the safety limit value at an earthquake intensity of 0.2 g, whereas these limit values were only exceeded at an earthquake intensity of 0.3 g when EDS is ignored. When the earthquake intensity reached 0.5 g, the influence on the derailment coefficient was greater but the difference in the wheel axle lateral forces was not significant with or without considering EDS. It is suggested that EDS should be considered when post-seismic running safety of LCBTCGBs are analyzed; otherwise, it will lead to misjudgment of running safety after an earthquake.

Numerical study of the spontaneous ignition mechanisms of pressurized hydrogen released inside pipes with different structures

Hydrogen is considered a key clean energy carrier to achieve the global goal of carbon neutrality. But spontaneous ignition can occur when pressurized hydrogen is released into pipes, and the presence of different pipe structures will significantly affect the ignition mechanism. In this work, the effects of varied pipe structures on the shock wave propagation and spontaneous ignition characteristics are investigated by numerical simulation with the DNS-like approach, EDC combustion model, and 21-step detailed hydrogen combustion mechanism. Results show that the simulation is in well agreement with the experimental data. Five dominant spontaneous ignition mechanisms are provided depending on different pipe structures. Among all types of pipe structures investigated, contraction structures can lead to a greater increase in shock wave pressure due to more severe shock wave reflection and convergence. While enlargement structures can contribute to more mixing of hydrogen and air, causing more sufficient combustion. This study provides a comprehensive understanding and clear safety guidance to inform the practical application of hydrogen energy.

Innovative Perspectives on Ecological Assessment in the Agro-Pastoral Ecotone of Inner Mongolia: An Integrated Evaluation and Forecast of Landscape and Ecological Risks and Drivers

The agro-pastoral ecotone of Inner Mongolia, one of China’s most ecologically vulnerable regions, requires careful evaluation and prediction of landscape ecological risks to improve its environment and support sustainable development. Our study built a model to assess the landscape ecological risks from 1990 to 2020 using land use data from Google Earth Engine. We examined the changes in landscape ecological risks and their driving factors through spatial autocorrelation analysis and geographic detectors. Future ecological risks from 2025 to 2040 were predicted using the multi-criteria evaluation-cellular automata-Markov model. Results revealed a declining trend in both disturbance and loss intensity across land use types, with the overall ecological risk index also decreasing. Higher risk areas were concentrated in the east and southwest, while lower risks were observed in the north and center. Temperature and precipitation are key natural factors, while the impact of Gross Domestic Product (GDP), a human factor, on ecological risk is increasing and surpassed natural influences in 2015 and 2020. In the future, the highest risk areas will remain in the southwest and northeast. This study provides detailed evidence and guidance for ecological safety and sustainable development in the agro-pastoral ecotone of Inner Mongolia.

A Brief Overview of Radiation Safety Guidance for Airport X-Ray Security Screening

A Brief Overview of Radiation Safety Guidance for Airport X-Ray Security Screening

Development and Assessment of a Point-of-Care Application (Genomic Medicine Guidance) for Heritable Thoracic Aortic Disease.

Genetic testing can determine familial and personal risks for heritable thoracic aortic aneurysms and dissections (TAD). The 2022 American College of Cardiology/American Heart Association guidelines for TAD recommend management decisions based on the specific gene mutation. However, many clinicians lack sufficient comfort or insight to integrate genetic information into clinical practice. We therefore developed the Genomic Medicine Guidance (GMG) application, an interactive point-of-care tool to inform clinicians and patients about TAD diagnosis, treatment, and surveillance. GMG is a REDCap-based application that combines publicly available genetic data and clinical recommendations based on the TAD guidelines into one translational education tool. TAD genetic information in GMG was sourced from the Montalcino Aortic Consortium, a worldwide collaboration of TAD centers of excellence, and the National Institutes of Health genetic repositories ClinVar and ClinGen. The application streamlines data on the 13 most frequently mutated TAD genes with 2286 unique pathogenic mutations that cause TAD so that users receive comprehensive recommendations for diagnostic testing, imaging, surveillance, medical therapy, and preventative surgical repair, as well as guidance for exercise safety and management during pregnancy. The application output can be displayed in a clinician view or exported as an informative pamphlet in a patient-friendly format. The overall goal of the GMG application is to make genomic medicine more accessible to clinicians and patients while serving as a unifying platform for research. We anticipate that these features will be catalysts for collaborative projects aiming to understand the spectrum of genetic variants contributing to TAD.

Dynamic Analysis and Temporal Governance of Safety Risks: Evidence from Underground Construction Accident Reports

Due to the complexity and dynamics of underground construction projects, safety risk management has experienced significant challenges restricting the sustainable development of underground space. The research on risk causal chains and risk coupling has yet to reveal the dynamic interactive characteristics of these risk factors and their temporal relationships over time. This study utilized a complex system view for safety risk analysis, using 37 accident investigation reports of underground construction projects. Combined with two novel and emerging analytical methods, temporal qualitative comparative analysis and crisp-set qualitative comparative analysis, this study discusses the temporal relationship of risk factors to the cause of accidents and explores the multi-actor coupling characteristics of management risk. The findings indicate that (1) compared with general construction projects, underground construction should pay more attention to management safety risks because they have an obvious time lag effect expressed in all accident causation paths, namely, preceding management risk, management risk, and machine/material risk cross-concurrently, and management risk initiation and (2) underground construction project management risks have three key main paths, namely, single-actor-dominated management deficiency (supervisors, owners, and subcontractors that cause management risks as a single-core actor) and dual-actor-dominated management deficiency (owner and subcontractor as dual core actors of management risk). Multi-actor-dominated management deficiency (owners, subcontractors, and supervisors are the multiple core actors of management risk). This study thus developed a temporal governance framework of underground construction safety risks based on the synergy of multi-actors and proposed risk governance strategies, such as synergistic multi-actor governance, to consider the temporal relationship of safety risk. This study further reveals the temporal and coupling characteristics of safety risks to enrich the risk casual chain theory and risk coupling theory and establish a systematic risk analysis framework for new guidance for safety and risk management for underground construction projects.

An Outbreak Investigation of Salmonella Weltevreden Illnesses in the United States Linked to Frozen Precooked Shrimp Imported from India – 2021

In 2021, the U.S. Food and Drug Administration (FDA), Centers for Disease Control and Prevention (CDC), and state partners investigated a multistate sample-initiated retrospective outbreak investigation (SIROI) consisting of a cluster of nine Salmonella Weltevreden illnesses associated with frozen, precooked shrimp imported from India. Import surveillance testing identified Salmonella Weltevreden recovered from a cooked shrimp sample from Supplier B. In total, nine patients with clinical isolates highly related via whole genome sequencing were reported in four states with illness onset dates between February 26 and July 17, 2021. Epidemiologic data were gathered by state partners for seven patients, who all reported exposure to shrimp. Five patients reported consuming shrimp cocktail from the same retailer. A traceback investigation for five of the six patients converged on Supplier B. This evidence demonstrated that the outbreak of Salmonella Weltevreden illnesses was caused by the consumption of cooked, ready-to-eat shrimp manufactured by Supplier B. At the time of the investigation, outbreak and recall information was shared with Indian competent authorities. In March 2022, a follow-up inspection of Supplier B’s facility in India was conducted, and insanitary conditions and practices were observed. This outbreak investigation highlighted the importance of multidisciplinary national and international public health partnerships. The lessons learned from this investigation should continue to inform investigational activities and food safety guidance for the industry.

Efficiency of natural and forced convection systems in cooking ham: Industrial scale validation

AbstractThis study evaluated the efficacy of cooking processes in natural and forced convection systems, for ensuring microbiological safety in industrial‐scale ham production. The cold point of the tanks was determined by measuring the water temperature every 2 min, with a maximum variation of 1.4°C between different regions of the tanks. The calculation of the lethal value (Fcal) was carried out using Enterococcus faecalis as the target microorganism due to its high resistance to heat treatment. The cooking temperature was measured at the geometric center of the ham and, in both convection systems, it reached the Fref value (23.6 min), necessary to achieve a reduction of 8 log (8 D), with Fcal of 45.7 and 45 min of cooking in the natural and forced convection systems. Both convection systems achieved microbial reductions exceeding 15‐log cycles (15 D), surpassing regulatory requirements despite occasional core temperatures below standard thresholds. In both systems (natural and forced), the cold spot was found on the left side, at a lower height, and toward the front of the tank. After heat treatment, no microorganisms were detected in the ham cooked in natural or forced convection systems. Both systems (natural and forced convection) proved viable at an industrial scale, provided that appropriate cooking protocols are followed.Practical ApplicationsThe practical applications of this study are significant for the food industry and regulatory bodies involved in food safety. These include quality assurance in ham production, food safety compliance, process optimization, risk mitigation, and guidance for industrial practices. Overall, this study has practical implications for improving food safety, quality control, and production efficiency in the ham industry. It fills a gap in validation studies on industrial‐scale ham cooking, providing valuable information for industry stakeholders and regulatory bodies alike.

Integrating firearm storage and safety devices into health care.

Millions of US children and adolescents live in homes with loaded firearms, with only half of these homes securing their guns. Firearm-related deaths among youth have doubled over the past decade, making firearms the leading cause of death for children and adolescents in the United States. The recent advisory by the US Surgeon General, identifying firearm violence as a public health crisis, underscores the urgent need for responsible firearm ownership, including safe firearm storage. However, the healthcare community currently lacks durable medical equipment (DME) codes for firearm storage devices, limiting the ability of healthcare providers to support responsible gun ownership. We propose the establishment of DME codes for firearm storage and safety devices, which would facilitate insurance coverage of these vital prevention measures. Durable medical equipment codes would empower physicians and other healthcare providers to integrate anticipatory guidance and lethal means counseling of firearm safety into routine care and support hospital- and community-based efforts to prevent firearm-related injuries and deaths among children and adolescents.

Correlation of fatty acids, glyceride core aldehydes, and polycyclic aromatic hydrocarbons during the thermal oxidation of hazelnut oil

Fatty acids in edible oil will be oxidized into aldehydes and ketones during hot processing, which will produce polycyclic aromatic hydrocarbons (PAHs) and other harmful substances to human health. Hazelnut oil was heated under different temperatures and times. For each type of oil sample, fatty acid composition, glyceride core aldehyde (GCAs), and PAHs were investigated. The correlation between these indicators was analyzed by the Pearson correlation coefficient. As the main component of hazelnut oil, oleic acid plays an essential role in the formation of GCAs. For GCAs, 9-oxo and 10-oxo-8 compounds were detected. The content of 9-oxo increased with the temperature, while there was no significant change in 10-oxo-8. There exist 15 kinds of PAHs in hazelnut oil. Correlation result shows that GCAs were strongly correlated with six kinds of PAHs (BaA, CHR, BbF, PYR, BaP, and IPY), which shows that GCAs are the precursor of several kinds of PAHs. The research provides strong theoretical guidance for the edible safety and control methods of hazelnut oil.

A review of mask fit testing data associated with protocols utilized in evaluating the efficacy of N95 masks for health care workers.

Quantitative mask fit testing (QNFT) is the gold standard to confirm the correct fit of a N95/P2 mask to ensure health care workers protection from airborne viruses. Using the Occupational Safety and Health Administration (OSHA) guidance indicates a final fit test result is a cumulative score derived from manoeuvres within the OSHA protocol. The protocol-based manoeuvres mimic aspects of clinical care by health professionals and mask fit testing is conducted to provide protection from airborne viruses and pollutants within a care setting. To determine whether studies undertaking QNFT report the results of individual manoeuvres of the OSHA protocol. A comprehensive search strategy for the systematic review was developed to determine eligible studies, published between May 2011 and May 2021. Two researchers independently screened all full text articles retrieved and all disagreements were resolved through discussion. The search found 557 studies. After removing 119 duplicates, 437 articles were reviewed based on title and abstract, 411 studies were excluded. Twenty-seven full text articles were assessed for eligibility, all were excluded for the following reasons: study did not report the results of the long or short OSHA protocol (12), study did not assess mask fit using the long or short OSHA protocol (10), article type (discussion/commentary/editorial) or wrong study type (1). Despite the use of very broad search terms no eligible studies were found and the result was declared an empty review. Internationally accepted QNFT protocols have a number of manoeuvres that reflect health care workers' physical movements during the delivery of clinical care. Studies of mask fit testing appear to lack the reporting of outcomes for each manoeuvre with only the cumulative results being provided. This finding raises the need to understand potential risk from a mask leak during the delivery of clinical care as evidenced by failing a manoeuvre during mask fit testing. Further research is required to understand the importance of passing each mask fit testing manoeuvre and the relationship to airborne protection during the delivery of clinical care.

Compressive load analysis of mechanical setting process of test string Packer in Ultra-high-pressure Gas Wells

ABSTRACT To address the packer setting problems under complex operating conditions in ultra-high pressure gas wells, a mechanical analysis model for the mechanical setting process of packer in ultra-high pressure gas wells is established. The model takes into account factors such as wellbore trajectory, bending moment, internal and external fluid pressure, and the coupled effect of axial load, frictional resistance and buckling. The established model can be used to calculate the axial force of tubing string in ultra-high pressure gas wells, and analyze the effects of the tubing string length below packer, line weight combination, friction coefficient and the released wellhead suspended load on the packer setting force. The case calculation and parameter sensitivity analysis indicate that the original design of a high-pressure gas well cannot meet the requirements of packer setting. The setting performance of the packer can be effectively improved by adjusting the released wellhead suspended load, optimizing the tubing string length below the packer, reducing the friction coefficient and optimizing the length configuration of tubing string with small diameter. An increase in wellhead release weight by 60 kN was accompanied by a corresponding increase in packer pressure of 12.48 kN. When the lower string length was extended by 600 m, the packer weight without suspension was reduced by 65.34 kN, whereas the packer weight with release was diminished by 21.69 kN. Furthermore, an augmentation in the friction coefficient by 0.15 resulted in a decrease in the pressure weight of the packer under release suspension by 55.79 kN. Additionally, a reduction in the small pipe diameter length by 1000 m caused an increase in the packer weight with a release load of 17.98 kN. The research content not only provides theoretical guidance for the long-term safety of test string in high-pressure gas wells, but also offers practical insights for the design and operation of packers.

Failure analysis and structural optimization of abnormal cracking of through-channel support seats of digital rail vehicles

In this paper, the failure analysis and structural optimization of a new type of digital rail vehicle throughway support bracket with abnormal cracking are investigated. This paper addresses the failure case of a new digital rail vehicle throughway bracket. From the simulation point of view and the vibration test point of view of the service line, it verifies and reproduces the reasons for the fatigue fracture failure of the original through-channel bracket structure. The fatigue fracture failure of the throughway bracket is caused by external excitation. The shortcomings of the optimized structure of the through-channel support filled with steel plates are explained from the simulation point of view and the fracture mechanics damage tolerance theory. The feasibility of the vibration decoupling optimized structure is completely evaluated from the service line perspective and simulation perspective, and the results show that the service environment load of the vehicle meets the life requirements, and the research method can provide guidance for the service safety and fatigue life assessment of other components of the new type of digital rail vehicles.

Antineoplastic Therapy Administration Safety Standards for Adult and Pediatric Oncology: ASCO-ONS Standards.

To update the American Society of Clinical Oncology (ASCO)-Oncology Nursing Society (ONS) standards for antineoplastic therapy administration safety in adult and pediatric oncology and highlight current standards for antineoplastic therapy for adult and pediatric populations with various routes of administration and location. ASCO and ONS convened a multidisciplinary Expert Panel with representation of multiple organizations to conduct literature reviews and add to the standards as needed. The evidence base was combined with the opinion of the ASCO-ONS Expert Panel to develop antineoplastic safety standards and guidance. Public comments were solicited and considered in preparation of the final manuscript. The standards presented here include clarification and expansion of existing standards to include home administration and other changes in processes of ordering, preparing, and administering antineoplastic therapy; the advent of immune effector cellular therapy; the importance of social determinants of health; fertility preservation; and pregnancy avoidance. In addition, the standards have added a fourth verification. Standards are provided for which health care organizations and those involved in all aspects of patient care can safely deliver antineoplastic therapy, increase the quality of care, and reduce medical errors.

Analysis and Real-Time Monitoring of the Influence of Wind Load on a High-Altitude Steel Connecting Bridge with Small Spacing

With the development of steel-structure construction technology in high-rise buildings, the design and construction of high-rise steel structures tend to be complicated. Based on the Zhuhai Tiejian Square project, the fluid-structure coupling calculation analysis and on-site monitoring are carried out in view of the wind load of the high-altitude steel-structure connecting bridge in the hoisting stage of the Zhuhai Tiejian Square project. The main structure of the project is four towers and five high-altitude, small-spacing steel structures connecting the four towers. The lifting process of the third zone is taken as the analysis object, and the hoisting idea of “low-altitude hoisting, overall lifting” is adopted. Because the span of the high-altitude steel-structure connecting bridge is small and the installation height is high, the influence of wind load on the hoisting process cannot be ignored. Therefore, the unidirectional fluid-structure coupling model of the high-altitude small-space steel-structure connecting bridge in the third zone was established by using CFD calculation software ANSYS Fluent 2022 R1, and the corresponding flow field and solid calculation results were obtained and analyzed. The analysis results show that the lifting structure still produces a certain deformation when the wind speed is 5 m/s or 10 m/s, and the calculation results show that the stress calculation results are still within the safe range of steel strength for the sensitivity of the lifting structure under wind load. With the increase of wind speed, the local maximum stress of the structure increases greatly, but the overall deformation remains stable, which indicates that the greatest challenge of hoisting steel structures under wind load may be the stability direction rather than the strength, so it is necessary to strictly monitor the displacement deformation of the structure during construction. Then, through the monitoring of the overall lifting process of the high-altitude, large-span, steel-connected structure of Zhuhai Tiejian Square from pre-lifting to formal lifting, real-time monitoring and data analysis show that the lifting process of the high-altitude steel bridge of Zhuhai Tiejian Square is safe and reliable, the force transformation of each component is reasonable, the lifting process is relatively stable, the external environment has little impact, and the expected monitoring effect has been achieved. The calculation simulation and on-site monitoring in this paper can provide theoretical and practical guidance for the construction safety under the influence of wind load in the construction process of high-altitude steel-structure hoisting, and provide an important reference value for similar projects.

Study on flammability limit and combustion reactions behaviors of R744/R152a environmentally friendly mixed working fluid by experiments and molecular dynamic simulation

R744/R152a mixture has broader application prospects. However, its thermodynamic and safety characteristics need to be fully considered. This paper presents the flammability characteristics and reaction mechanism of R744/R152a mixture by experimental and ReaxFF MD. Firstly, the flammable zones of the mixture with different ratios were tested on a high-precision experimental setup. Using a high-speed camera and an infrared thermographic record flame evolution characteristics and relative flame temperature of the mixture both lean and rich limits. The flammable zones of R152a are 0.386–0.685 (Φ) at y = 0. R744 was able to narrow the flammability zones of R152a. As the inert gas increases, the lean and rich limits merge, is 0.542 (Φ). Based on experimental studies, the inhibitory effect of R744 on the oxidation mechanism of R152a was investigated from the atomic level using ReaxFF MD. The results showed that the R744 increased the activation energy of the system from 52.08 kcal/mol to 55.73 kcal/mol, 52.18 kcal/mol, 57.04 kcal/mol, 52.93 kcal/mol, 52.98 kcal/mol, respectively. Reaction pathways and the rates of elementary reaction are significantly suppressed. The simplified mechanism of the oxidation can reveal the macroscopic phenomenon that R744 inhibits flame propagation. The results of this study provide safety guidance for R744/R152a applications.