Hazard Analysis Method Research Articles

Communication Network Reliability Under Geographically Correlated Failures Using Probabilistic Seismic Hazard Analysis

The research community’s attention has been attracted to the reliability of networks exposed to large-scale disasters and this has become a critical concern in network studies during the last decade. Earthquakes are high on the list of those showing the most significant impacts on communication networks, and simultaneously, they are the least predictable events. This study uses the Probabilistic Seismic Hazard Analysis method to estimate the network element state after an earthquake. The approach considers a seismic source model and ground prediction equations to assess the intensity measure for each element according to its location. In the simulation, nodes fail according to the building’s fragility curves. Similarly, links fail according to a failure rate depending on the intensity measure and the cable’s characteristics. We use the source-terminal, and the diameter constrained reliability metrics. The approach goes beyond the graph representation of the network and incorporates the terrain characteristics and the component’s robustness into the network performance analysis at an affordable computational cost. We study the method on a network in a seismic region with almost 9000 km of optical fiber. We observed that for source-terminal that are less than 500 km apart the improvements are marginals while for those that are more than 1000 km apart, reliability improves near a 30% in the enhanced designs. We also showed that these results depend heavily on the robustness/fragility of the infrastructure, showing that performance measures based only the network topology are not enough to evaluate new designs.

Intelligent HAZOP analysis method based on data mining

Accidents in production equipment are occurring with increasing frequency, which has caused serious negative impacts on society and petrochemical enterprises. It is important to learn prevention and control rules and lessons from accident cases to prevent accidents and improve intrinsic safety levels of enterprises. The hazard and operability (HAZOP) analysis method has been widely used for risk identification and accident prevention in petrochemical enterprises. However, the rules contained in many completed HAZOP analysis reports have not been deeply studied, inherited, or extensively applied. The analysis of a new process, however, relies on expert experience, which is usually subjective and time-consuming. This paper proposes an intelligent HAZOP analysis method based on data mining to explore the law of accident cause mechanisms, help promote intelligent analysis, and improve the accuracy of analysis results. A HAZOP analysis data table structure is proposed. The frequencies of all words in the process parameter, guide word, cause, and consequence were calculated, and the words were sorted based on the word frequency statistics method. Words with high word frequencies were considered key in formulating the safety inspection checklists. The latent Dirichlet allocation (LDA) model and contingency table were used to explain the correlation between the process parameters, guide words, causes, and consequences. The co-occurrence probability sequence of the elements can then be acquired. Using the naive Bayes algorithm, a method for calculating the likelihoods, severities, and risk levels of accidents is proposed. The accident risk ranks can be intelligently predicted to realize an intelligent HAZOP analysis. This study developed a software to help execute the method. The intelligent HAZOP analysis method was applied based on data from 14 petrochemical units; the raw oil buffer tank in the wax oil hydrocracking unit was taken as an example to illustrate the application of the method. The method provides a technical basis and basic guarantee for risk identification, accident prevention, and rescue of petrochemical plants.

Seismic hazard analysis for engineering sites based on the stochastic finite-fault method

Seismic hazard analyses are mainly performed using either deterministic or probabilistic methods. However, there are still some defects in these statistical model-based approaches for regional seismic risk assessment affected by the near-field of large earthquakes. Therefore, we established a deterministic seismic hazard analysis method that can characterize the entire process of ground motion propagation based on stochastic finite-fault simulation, and we chose the site of the Xiluodu dam to demonstrate the method. This method can characterize earthquake source properties more realistically than other methods and consider factors such as the path and site attenuation of seismic waves. It also has high computational efficiency and is convenient for engineering applications. We first analyzed the complexity of seismogenic structures in the Xiluodu dam site area, and then an evaluation system for ground motion parameters that considers various uncertainties is constructed based on a stochastic finite-fault simulation. Finally, we assessed the seismic hazard of the dam site area comprehensively. The proposed method was able to take into account the complexity of the seismogenic structures affecting the dam site and provide multi-level parameter evaluation results corresponding to different risk levels. These results can be used to construct a dam safety assessment system of an earthquake in advance that provides technical support for rapidly and accurately assessing the post-earthquake damage state of a dam, thus determining the influence of an earthquake on dam safety and mitigating the risk of potential secondary disasters.

Experimental study and model predictions on helium release in an enclosure with single or multiple vents

This paper presents experiments performed at Canadian Nuclear Laboratories (CNL) to examine the dispersion behaviour of helium in a polycarbonate enclosure that was representative of a residential parking garage. The purpose was to gain a better understanding of the effect of buoyancy- or wind-driven natural ventilation on hydrogen dispersion behaviour. Although hydrogen dispersion studies have been reported extensively in the literature, gaps still exist in predictive methods for hazard analysis. Helium, a simulant for hydrogen, was injected near the centre of the floor with a flow rate ranging from 5 to 75 standard litres per minute through an upward-facing nozzle, resulting in an injection Richardson number ranging between 10−1 and 102. The location of the nozzle varied from the bottom of the enclosure to near the ceiling to examine the impact of the nozzle elevation on the development of a stratified layer in the upper region of the enclosure. When the injection nozzle was placed at a sufficiently low elevation, the vertical helium profile always consisted of a homogenous layer at the top overlaying a stratified layer at the bottom. To simulate outdoor environmental conditions, a fan was placed in front of each vent to examine the effect of opposing or assisting wind on the dispersion. The helium transients in the uniform layer predicted with analytical models were in good agreement with the measured transients for most tests. Model improvements are required for adequately predicting transients with primarily stratified profiles or strong opposing wind.

Application of Hazard and Operability Analysis (HAZOP) Method for Risk Analysis in CGS Station

Background: The hazard and operability study (HAZOP) method is a risk assessment method based on engineering systems used for qualitative analysis or quantitative evaluation. It is mainly used to discover potential hazards and operational difficulties in the design and qualitative stages of chemical systems. The study aims to apply the HAZOP method in process and safety operations at gas depressurization station.
 Methods: This descriptive study was performed at CGS station. The station was divided into four principal nodes including: filter, heater, regulator, and odorize part. Required information for HAZOP worksheets were gathered by operational procedures, daily reports and interviews with engineers and operators working at the station. To determine the severity of consequences and probability of occurrence of scenarios that were predicted based on the risk matrix, the amount of risk was specified and the necessary suggestions were made in this regard.
 Results: According to this study, the operational indicators in the pressure reducing station process included pressure, flow, level and temperature. 22 main deviations and 50 causes of failures were identified. 5 deviations (23%) were in the low risk range (green area) and 17 (77%) were in the medium risk range (yellow area).
 Conclusions: Causes and effects of deviations in operational parameters at four nodes in gas depressurization station were identified by HAZOP. Preventive actions were emphasized, such as consistent inspection of pipelines, preventive and timely maintenance and preparing a well-scheduled plan for inspecting the equipment in terms of corrosion, inspection, and design revision.

Earthquake Risk Probability Evaluation for Najin Lhasa in Southern Tibet

The probabilistic seismic hazard analysis (PSHA) method is effectively used in an earthquake risk probability evaluation in seismogenic regions with active faults. In this study, by focusing on the potential seismic source area in Najin Lhasa, southern Tibet, and by incorporating the PSHA method, we determined the seismic activity parameters and discussed the relationship of ground motion attenuation, the seismic hazard probability, and the horizontal bedrock ground motion acceleration peak value under different transcendence probabilities in this area. The calculation results show that the PSHA method divides the potential source area via specific tectonic scales and detailed tectonic markers, which reduces the scale of the potential source area and better reflects the uneven spatial distribution of seismic activity in the vicinity of Najin. The corrected attenuation relationship is also in line with the actual work requirements and is suitable for earthquake risk analysis. In addition, the major influences on the peak acceleration of ground motion in the study area are mainly in the potential source areas of Qushui (M7.5), Dangxiong (M8.5), and Kangma (M7.5). The peak horizontal ground motion acceleration (PGA) with a transcendence probability of 10% in 50 years is 185.9 cm/s2, and that with a transcendence probability of 2% in 50 years is 265.9 cm/s2.

A conceptual framework integrating numerical simulation with system theory based method for quantitative explosion process hazard analysis

Explosion is a significant threat to chemical process safety, which often occurs suddenly with a wide range of impact, resulting in catastrophic disasters. Predictions of explosion hazards are required for regional safety assessment and disaster resilience enhancement of chemical industrial parks (CIPs). This paper, therefore, aims to develop a conceptual framework for systematically analyzing explosion evolutions and quantifying the potential hazards by combining system-theoretic process analysis (STPA) method with numerical simulation. The proposed framework consists of 5 steps: (i) establishment of hierarchical safe control structures (SCSs) of important chemical processing zones in the CIP, (ii) computational fluid dynamics (CFD) modeling for potential explosion evolutions in each zone by changing the examined parameters randomly, (iii) development of a convolutional neural network (CNN) prediction model through constant self-learning of CFD pressure field data, (iv) comprehensive assessment of blast damage by incorporating the outputs of the above numerical models into existing evaluation methods, (v) identification of unsafety control actions and causes, and safety constraints for the improvement of SCSs. Provided with monitoring data, the developed analysis architecture can predict explosion process hazards and recommend appropriate safety strategies in real time. This would service the multi-level requirements for explosion prevention and protection, supporting better-informed decision-making. The paper describes the concepts and implementation process of the method as a first step.

Analysis of Soil Acceleration in The Mentawai Region with The Method Probabilistic Seismic Hazard Analysis (PSHA)

The Mentawai Islands are one of the areas that are active in seismicity. An earthquake measuring 7.2 on the Richter scale on October 25, 2010 resulted in many casualties and material losses. Many buildings collapsed and facilities were damaged so that space managers needed a seismic hazard map to be able to organize the space by considering the disaster aspect. This prompted researchers to conduct research aimed at making seismic hazard maps and knowing the level of earthquake hazard in the Mentawai region. Seismic hazard maps are useful in planning earthquake-resistant buildings and can describe the effects of earthquakes at a location which will help in anticipating community preparedness and earthquake disaster mitigation efforts. Seismic hazard data processing uses the Probabilistic Seismic Hazard Analysis (PSHA) method. PSHA is based on earthquake parameters that produce the largest ground motion. The magnitude of the intensity at a location due to an earthquakein the earthquake source area with a magnitude of M and a distance of R, the attenuation function can be used. The attenuation functions in this study are Joyner-Boore (1997) and Young et al (1997). This type of research is descriptive, namely by collecting NEIC/USGS earthquake catalog data for the period 1950 - 2021 with M 5 SR.The results of this study indicate that the area of ywhich has a high level of seismic hazard is found in the Siberut area with a maximum PGA range of 1.17 g - 3.70 g. The area with a low seismic hazard level is the Pagai area with a PGA range of 0.80 g - 2.86 g. This result represents a 10% chance of being exceeded in 50 years.

Seismic Hazard Analysis Using Fuzzy-Probabilistic Approach for Chennai City, South India

Fuzzy-probabilistic seismic hazard analysis (FPSHA) is performed for Chennai city, South India incorporating both the random and fuzzy uncertainties. Randomness is handled using Monte-Carlo simulation technique, and fuzziness is accounted in the hazard analysis using fuzzy logic. The magnitude of earthquakes and epicentral distances are fuzzified and used as inputs in the fuzzy inference rules. Fuzzy attenuation relationships are developed as consequence of the inference rules with the help of ground-motion models and ANFIS. The proposed FPSHA method has the advantage over the conventional hazard analysis methods in respect of its preciseness, efficiency, practicability, and reliability. The ground motions compatible with the target spectrum (UHS) of 475 years return period are selected from the recorded accelerograms with appropriate scaling. The established spectrum compatible accelerograms are vital in the seismic analysis and design of infrastructure facilities and rehabilitation and strengthening of historical and critical structures.

Seismic microzoning of the Delhi metropolitan area, India—II: Hazard computation and zoning maps

AbstractWe present seismic microzonation maps of New Delhi, India, using the probabilistic seismic hazard analysis (PSHA) method with input seismic activity parameters estimated in Part‐I of this two‐part paper. Our calculations required three different attenuation equations for amplitude scaling of strong ground motion from three principal contributing sources: the National Capital Region (NCR), Northwestern Himalaya (NWH), and the Hindu Kush subduction (HKS). We show that uniform hazard spectral (UHS) amplitudes are dominated only by the local seismicity in the NCR at high frequencies beyond about 2 Hz. For intermediate and long periods, UHS amplitudes are dominated by contributions from the NWH and HKS earthquakes. Our results show that specifying strong motion amplitudes for use in engineering design by means of peak ground acceleration can lead to serious errors for buildings higher than four to five stories and hence should not be used. Our results also show that the shape of design spectra must depend on the nature of contributing earthquake sources, their relative activity, potential to create large magnitudes, and geographical placement relative to the site of interest, and thus a standard design‐spectrum shape cannot satisfy all these requirements. We use local geological site condition parameters directly in all calculations and present hazard maps for three different soil site conditions (“rock,” stiff soil sites, and deep soil sites). Thus, the user can extract the UHS amplitudes of pseudo relative velocity spectra at any site in the National Capital Territory by experimentally determining the local soil site conditions and then applying the corresponding maps shown in this paper.

Modeling and Simulation in an Aircraft Safety Design Based on a Hybrid AHP and FCA Algorithm.

Throughout the world, the reliability-based approach to safety design of aircraft systems is quite mature and widely used. However, there are still shortcomings in the reliability-based aircraft system safety analysis method. It cannot dynamically analyze the accident evolution process and lack consideration of the complex situation of multifactor coupling. On the basis of the original aircraft system safety analysis method, this paper innovatively proposes a functional hazard analysis (FHA) method based on the analytic hierarchy process (AHP) and multifactor fuzzy comprehensive assessment (FCA). The purpose is to improve the objectivity and quantification of the FHA method in the safety design of aircraft systems. At the same time, in the terminal airworthiness verification, this paper proposes a repeatable and controllable virtual test flight verification method, which aims to reduce the cost and cycle of the terminal airworthiness verification and expand the coverage of the envelope verification. Finally, combined with the clauses in MIL-HDBK-516B, a case calculation is carried out to verify the feasibility of the proposed method.

Use of Hybrid Causal Logic Method for Preliminary Hazard Analysis of Maritime Autonomous Surface Ships

Recently, the safety issue of maritime autonomous surface ships (MASS) has become a hot topic. Preliminary hazard analysis of MASS can assist autonomous ship design and ensure safe and reliable operation. However, since MASS technology is still at its early stage, there are not enough data for comprehensive hazard analysis. Hence, this paper attempts to combine conventional ship data and MASS experiments to conduct a preliminary hazard analysis for autonomy level III MASS using the hybrid causal logic (HCL) method. Firstly, the hazardous scenario of autonomy level III MASS is developed using the event sequence diagram (ESD). Furthermore, the fault tree (FT) method is utilized to analyze mechanical events in ESD. The events involving human factors and related to MASS in the ESD are analyzed using Bayesian Belief Network (BBN). Finally, the accident probability of autonomy level III MASS is calculated in practice through historical data and a test ship with both an autonomous and a remote navigation mode in Wuhan and Nanjing, China. Moreover, the key influence factors are found, and the accident-causing event chains are identified, thus providing a reference for MASS design and safety assessment process. This process is applied to the preliminary hazard analysis of the test ship.

Analisis Bahaya Gempa Bumi Menggunakan Metode Probabilistic Seismic Hazard Analysis Di Wilayah Likupang, Minahasa Utara

The Probabilistic Seismic Hazard Analysis (PSHA) method is a method used in seismic hazard analysis based on the definition of a probability distribution function that takes into account and combines the uncertainties of the earthquake event scale, location, and frequency of occurrence, to obtain a comprehensive picture of the hazard level or a location that reviewed. The Likupang area, North Minahasa is a location that is prone to earthquake disasters, for this reason, early mitigation is needed, one of which is mapping the potential for disaster hazards. Maximum ground vibration acceleration (PGA) is the greatest value of ground acceleration at a place caused by earthquake vibrations in a certain period of time. In this study, the results of the PSHA calculation in the North Minahasa Likupang area were obtained, the largest PGA value was 1.4g–1.8g, tilapia SA T= 0.2 seconds was 1.7g-2.1 and SA T=1 value, 0 seconds is 0.5g – 0.6g. Based on these results, the danger of light to severe damage can be caused.

Comparison of Various Types of Seismic Hazard Assessment and their Influence on Structural Vulnerability

This work sought at enhancing techniques for the assessment of seismic risk in order to understand displacement effects and impacts of different seismic hazard estimation techniques on structural vulnerability. The analysis is useful because the number of earthquakes around the world is on the rise, and there is a necessity to eliminate the potential threat. Weighted Average of Ground Motion intensities was used to determine hazard parameters, along with PSHA and DSHA. The information regarding seismicity was collected from the regional networks and catalogs with the help of geotechnical investigation for site characteristics. An assessment of structural resilience was accomplished with building inventories and retrofit projects data with the help of FEA for computational modeling. The degree of earthquake was recorded to be from 4. 5 to 7. 5 Mw, with PGA ranging from 0 to 0. 2 to 0. 3g. During preliminary screening, Sites were ranked into high PSA and low PSA divides as well as Low Seismic Hazard and Medium to High Seismic Hazard. These retrofitting measures such as base isolation and strengthening further improved performance of buildings, in that they reduced peak drift ratios by up to 50% and, base shear force capacity by 30% of average value. The Effectiveness Index of retrofitting work varied from 0. 732 to 0. 912, from which one can draw the conclusion concerning appreciable enhancements of earthquake resistance. The study thereby laid a foundation to prove that it is possible to reduce the seismic risk by using the advanced hazard analysis methods and based on these analyses, some systematic retrofit interventions are effective enough in achieving the objective of sustainable urban development. The conclusions derived in this paper present quantitative information relevant for understanding actions toward earthquake prevention in vulnerable territories.

A systems-theoretic hazard analysis for safety-critical medical gas pipeline and oxygen supply systems

Medical gas systems are safety-critical systems due to their association with critical care situations. In particular, the oxygen gas supply system contains many complications represented in the interactions between human and equipment while operating the system and managing emergencies. Therefore, it contains many hazards that require high safety standards to maintain the integrity of the system. The traditional hazard analysis methods suffer from weaknesses as their linear reasoning assumption cannot adequately describe the actual behavior of modern socio-technical systems that are characterized by tight couplings and complex interactions among technical, human and organizational aspects. Alternatively, Systems Theoretical Process Analysis (STPA) is a new hazard analysis approach that accounts for the causal relationships between system components and their unsafe interactions, allowing the integration of both occupational and process safety. STPA is widely used in the automotive, aviation, and aerospace industries whereas there are a few applications of STPA in healthcare domain. This paper proposes the use of STPA methodology in analyzing the hazards related to the medical gas pipeline and oxygen supply systems in a low-medium income country. Specifically, the analysis considers the emergencies that stem from the total or partial failure of oxygen supply and the hazards related to temporary restoration of the medical oxygen system. The results indicate that STPA contributes to identifying the hazards resulting from the interference between the human, machines, and equipment, and studying the unsafe effect of the system elements on each other. This research suggests control measures to prevent the unsafe interaction of the system components and improve the response time to oxygen failure incidents, which greatly reduces the potential consequences.

Obese Lung Recipients May Be Susceptible to Severe COVID-19 Outcomes Compared to Controls

PurposeObesity is thought to increase COVID-19 (C19) related morbidity and mortality in nontransplant patients; however, the data in lung transplant literature are lacking. We aimed to study impact of body mass index (BMI) on outcomes of lung transplant recipients (LTR) with C19.MethodsFrom March 2020 to August 2021, 91 lung recipients with C19 were included and classified as controls (BMI <30 kg/m2) and obese (BMI ≥30 kg/m2) at the time of LT listing. Primary outcome was death. Secondary outcome was C19-related medical morbidity. Cox proportional hazard analysis and Kaplan-Meier method were used.ResultsControls (69%, n=63) and obese (31%, n=28) subjects were comparable in terms of baseline characteristics before C19 onset. Compared to controls, obese subjects tended to have more severe inflammation and a higher prevalence of hypoxemia, requirement of ICU, mechanical ventilation, and death (Table 1). Also compared to controls, the risk of death tended to be higher and probability of survival tended to be lower in obese subjects (HR: 1.971 [0.956-4.065], p=0.066 and 73% vs 53.6%, p=0.061, respectively; Figure 1). However, coinfections and post-C19 allograft function were comparable between the two groups (Table 1). Of note, mycophenolate was stopped or reduced upon/during hospitalization in both groups alike.ConclusionIn our study, obese LTRs trended toward an increased risk of death from C19 compared to controls. This is the first data on the impact of obesity on C19 in LTRs. The role of leptin as a pro-inflammatory substance can be speculated.

Hazard Analysis Techniques, Methods and Approaches: A Review

Hazard analysis (HA) is an indispensable task during the specification and development of safety-critical systems. It involves identifying potential forms of harm, their effects, causal factors, and the level of risk associated with them. Systems are always vulnerable to mishaps, hazards, or risks that result in system failures, resulting in injuries, loss, and damage. Even though previous studies have made a significant contribution to the study of hazard analysis, little effort has been made to give an overview of the common HA techniques, highlighting their responsibilities, advantages, and disadvantages. Thus, this paper aims to focus on and feature the existing HA techniques along with their respective functions. An overall picture of the advantages and disadvantages of listed HA techniques is presented as well in this paper. Such a study may be utilized as a guide to aid researchers and practitioners in understanding hazard analysis. The investigation is conducted using a process-oriented approach that consists of three steps: formulation of the research questions, the gathering of related studies, and the analysis of the extracted studies. The study revealed a total of 22 HA techniques. A further study is to propose and carry out a systematic literature review to identify to what extent the hazard analysis techniques have been implemented and evaluated in case studies.

Comparative Risk Assessment of Covid-19 Infection among Personnel Working in a Medical Environment: A Field Study Using Rapid Covid-19 Hazard Analysis (RCHA) Method

Comparative Risk Assessment of Covid-19 Infection among Personnel Working in a Medical Environment: A Field Study Using Rapid Covid-19 Hazard Analysis (RCHA) Method

Classifying hazardous movements and loads during manual materials handling using accelerometers and instrumented insoles

Improper manual material handling (MMH) techniques are shown to lead to low back pain, the most common work-related musculoskeletal disorder. Due to the complex nature and variability of MMH and obtrusiveness and subjectiveness of existing hazard analysis methods, providing systematic, continuous, and automated risk assessment is challenging. We present a machine learning algorithm to detect and classify MMH tasks using minimally-intrusive instrumented insoles and chest-mounted accelerometers. Six participants performed standing, walking, lifting/lowering, carrying, side-to-side load transferring (i.e., 5.7 kg and 12.5 kg), and pushing/pulling. Lifting and carrying loads as well as hazardous behaviors (i.e., stooping, overextending and jerky lifting) were detected with 85.3%/81.5% average accuracies with/without chest accelerometer. The proposed system allows for continuous exposure assessment during MMH and provides objective data for use with analytical risk assessment models that can be used to increase workplace safety through exposure estimation.

Automated information support system for AOR methods of hazard and risk analysis for oil and gas industry

This article examines an attempt to formalize the procedures preceding the engineering methods of AOR, which allows experts to give the maximum of really significant information in a concise form and with a pronounced effect, freeing their limited resources from routine and search for insignificant versions of events to the detriment of the most important.