scholarly journals A Causal Network-Based Risk Matrix Model Applicable to Shield TBM Tunneling Projects

2021 ◽  
Vol 13 (9) ◽  
pp. 4846
Author(s):  
Heeyoung Chung ◽  
Jeongjun Park ◽  
Byung-Kyu Kim ◽  
Kibeom Kwon ◽  
In-Mo Lee ◽  
...  
Keyword(s):  
Risk Analysis ◽  
Matrix Model ◽  
Tunnel Boring Machine ◽  
Shield Tunnel ◽  
Risk Level ◽  
Causal Network ◽  
Risk Matrix ◽  
Advantages And Disadvantages ◽  
Causal Networks ◽  
Analysis Models

The present study compares and analyzes three risk analysis models that are applicable to shield tunnel boring machine (TBM) tunneling, and thus proposes an improved risk matrix model based on the causal networks applicable to sustainable tunnel projects. The advantages and disadvantages of three risk analysis models are compared, and causal networks are structured by analyzing the causal relationship between risk factors and risk events. Based on the comparison and analysis results, the causal network-based risk matrix model (CN-Matrix model), which complements the disadvantages and exploits the advantages of the three existing models, is proposed in this paper. Furthermore, this study suggests a means of modifying the weighting scores in the estimation of the risk score, which permits the CN-Matrix model to determine the risk level more reasonably. Thus, the improved CN-Matrix model is more reliable and robust compared to the three existing models.

scholarly journals Numerical Simulation of EPB Shield Tunnelling with TBM Operational Condition Control Using Coupled DEM–FDM

2021 ◽  
Vol 11 (6) ◽  
pp. 2551
Author(s):  
Hyobum Lee ◽  
Hangseok Choi ◽  
Soon-Wook Choi ◽  
Soo-Ho Chang ◽  
Tae-Ho Kang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Tunnel Boring Machine ◽  
Chamber Pressure ◽  
Screw Conveyor ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Operational Conditions ◽  
Shield Tunnelling ◽  
Epb Shield

This study demonstrates a three-dimensional numerical simulation of earth pressure balance (EPB) shield tunnelling using a coupled discrete element method (DEM) and a finite difference method (FDM). The analysis adopted the actual size of a spoke-type EPB shield tunnel boring machine (TBM) consisting of a cutter head with cutting tools, working chamber, screw conveyor, and shield. For the coupled model to reproduce the in situ ground condition, the ground formation was generated partially using the DEM (for the limited domain influenced by excavation), with the rest of the domain being composed of FDM grids. In the DEM domain, contact parameters of particles were calibrated via a series of large-scale triaxial test analyses. The model simulated tunnelling as the TBM operational conditions were controlled. The penetration rate and the rotational speed of the screw conveyor were automatically adjusted as the TBM advanced to prevent the generation of excessive or insufficient torque, thrust force, or chamber pressure. Accordingly, these parameters were maintained consistently around their set operational ranges during excavation. The simulation results show that the proposed numerical model based on DEM–FDM coupling could reasonably simulate EPB driving while considering the TBM operational conditions.

scholarly journals P276 Risk matrix model for prediction of one-year surgery in Crohn’s disease

2018 ◽  
Vol 12 (supplement_1) ◽  
pp. S240-S241
Author(s):  
N Imperatore ◽  
A Rispo ◽  
A Testa ◽  
L Bucci ◽  
G Luglio ◽  
...  
Keyword(s):  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Matrix Model ◽  
Risk Matrix ◽  
One Year

INDEPENDENCE IN COMPLETE AND INCOMPLETE CAUSAL NETWORKS UNDER MAXIMUM ENTROPY

2008 ◽  
Vol 16 (05) ◽  
pp. 699-713 ◽  
Author(s):  
MICHAEL J. MARKHAM
Keyword(s):  
Expert System ◽  
Probability Distribution ◽  
Maximum Entropy ◽  
Linear Constraints ◽  
Causal Network ◽  
Missing Information ◽  
Causal Networks ◽  
Small Set

In an expert system having a consistent set of linear constraints it is known that the Method of Tribus may be used to determine a probability distribution which exhibits maximised entropy. The method is extended here to include independence constraints (Accommodation). The paper proceeds to discusses this extension, and its limitations, then goes on to advance a technique for determining a small set of independencies which can be added to the linear constraints required in a particular representation of an expert system called a causal network, so that the Maximum Entropy and Causal Networks methodologies give matching distributions (Emulation). This technique may also be applied in cases where no initial independencies are given and the linear constraints are incomplete, in order to provide an optimal ME fill-in for the missing information.

scholarly journals Risk Analysis of Vegetables Marketing in Rwanda, A case of carrots and cabbages produced in Rubavu District and supplied across the country

2020 ◽  
Vol 56 (2) ◽  
Author(s):  
Jean Jacques KUBWIMANA
Keyword(s):  
Risk Analysis ◽  
Linear Regression Analysis ◽  
Secondary Data ◽  
Primary Data ◽  
Risk Level ◽  
Bivariate Analysis ◽  
Market Demand ◽  
Contractual Arrangements ◽  
Marketing Risk ◽  
Storage Network

Due to the perishable nature and biological nature of the production process there is difficulty in scheduling the supply of vegetables to market demand. The vegetables are subjected to higher prices and quantity risks with changing consumers’ demand and production conditions. The core focus of this study was to reach, measure, and analyzing the marketing risk level of vegetables produced in Rubavu District, Rwanda. The study based on a survey of 90 vegetable sellers. At least 30 couple of wholesalers and middlemen visited Rubavu District to trade the vegetables for various retails. Primary data collected through structured questionnaires and secondary data sources used. A Five-point Likert associated with the bivariate analysis was used to rank the risk level while the full model of Linear Regression Analysis and factor analysis were used to identifier the majors’ factors associated with the risk in vegetable marketing in Rwanda. The mean score results derived based on Likert-Scales, indicated that “low seasonal product prices, weak market channels, poor logistics, and market communications, poor product handling and packaging, lack of storage and higher perishability’ identified to be the most important sources of risk. Therefore, the use of forwards’ contracts; getting market information, sell at crude prices due to perishability, contractual arrangements, maintaining good relationships and restoring the storage network system were of significant concerns for overcoming the recognized risks.   Keywords: Risk, Risk analysis, Likert Scale, Marketing risk, Vegetable Marketing risk, and Risk Management.

scholarly journals ANALISIS POLA DAN RESIKO USAHA GULA AREN DI KABUPATEN REJANG LEBONG

2012 ◽  
Vol 11 (1) ◽  
pp. 1-11
Author(s):  
Felycia Tyera Kencana ◽  
Ketut Sukiyono ◽  
Bambang Sumantri
Keyword(s):  
Risk Analysis ◽  
Rainy Season ◽  
Descriptive Analysis ◽  
Simple Random Sampling ◽  
Dry Season ◽  
Risk Level ◽  
Cluster Sampling ◽  
Production Scale ◽  
Research Areas ◽  
Palm Sugar

This study is aimed at examining enterprises model and analysing risk level of Palm Sugar in Rejang Lebong Regency.  Risk Analysis involve nira harvested, nira processed, palm sugar production, and palm sugar prices received by producers.  Two-stages cluster sampling method is used to determine research areas, i.e, subdistrict of Sindang Kelingi and Selupu Rejang based on the numbers of  firms. Using similar critirea, two villages are selected, i.e, Air Meles Atas and Sindang Jati.  From those villages, then, 86 palm sugar producers are selected using Simple Random Sampling. Descriptive analysis is applied to describe entreprises model of palm sugar industries while risks is analysed using its varians, standard deviation, and minimum level of production as proposed by Maryam and Suprapti (2008).   The research shows that all palm sugar industries in this regency can be categories as home industries with average production scale of  11.58 kg per process in rainy season and 11. 54 kg in dry season. Palm sugar producers  use  their own capital to produce palm sugar and borrowed to palm sugar village merchants when they need.  From risk analysis, the study finds that palm sugar producers will face higher risk in term of nira harvested and processed, and production in dry season, except in term of price received which is higher in rainy season.  Over all, palm sugar producers will not face risk significantly both in dry and rainy season.Key words: Palm Sugar, Enterprises model, Risk analysis       

Risk assessment of threats in Czestochowa county based on the FEMA methodology

2020 ◽  
Vol 1 ◽  
pp. 53-68
Author(s):  
Monika Kowalczyk ◽  
Urszula Nowacka
Keyword(s):  
Risk Assessment ◽  
Risk Analysis ◽  
Emergency Management ◽  
Federal Emergency Management Agency ◽  
Management Agency ◽  
Advantages And Disadvantages ◽  
History Of ◽  
Detailed Assessment

The article presents a description of the methodology of the Federal Emergency Management Agency, which allows for a detailed assessment of each threat separately, in a numerical manner. The FEMA methodology uses four criteria: history of the event, vulnerability, probability and maximum threat. The aim and method of research was determined and the risk analysis of threats in Częstochowa County was estimated on the basis of FEMA methodology. The conducted research allowed to draw attention to the advantages and disadvantages of the FEMA methodology.

BUSINESS RISK ASSESSMENT METHODS

2021 ◽  
Vol 3 (4) ◽  
pp. 4-12
Author(s):  
S. A. FILIN ◽  
◽  
N. A. FADEEVA ◽  
Keyword(s):  
Risk Assessment ◽  
Risk Analysis ◽  
Assessment Method ◽  
Assessment Methods ◽  
Specific Situation ◽  
Business Risk ◽  
Advantages And Disadvantages ◽  
Risk Assessment Method ◽  
Modern Business ◽  
The Subject

In this article, the subject of research is the methods of risk assessment in business as the main way to minimize risks when choosing a particular scenario for the development of events, as well as the difficulty in choosing a method for further analysis. The purpose of this article is to identify the most appropriate risk assessment method for a given situation and, accordingly, compare them and analyze the advantages and disadvantages of the methods under consideration. The article provides examples for specific situations of the most commonly used risk assessment methods in modern business. Recommendations for the most effective application of the analyzed methods are offered, depending on the goal of risk analysis and a specific situation. The results and conclusions are presented, corresponding to the set goal.

scholarly journals Risk Assessment System Based on Fuzzy Composite Evaluation and a Backpropagation Neural Network for a Shield Tunnel Crossing under a River

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xiao Liang ◽  
Taiyue Qi ◽  
Zhiyi Jin ◽  
Shaojie Qin ◽  
Pengtao Chen
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Risk Assessment ◽  
Assessment System ◽  
Chamber Pressure ◽  
Shield Tunnel ◽  
Risk Level ◽  
Backpropagation Neural Network ◽  
Grouting Pressure ◽  
Simulation Results

Constructing a shield tunnel that crosses under a river poses considerable safety risks, and risk assessment is essential for guaranteeing the safety of tunnel construction. This paper studies a risk assessment system for a shield tunnel crossing under a river. Risk identification is performed for the shield tunnel, and the risk factors and indicators are determined. The relationship between the two is determined preliminarily by numerical simulation, the numerical simulation results are verified by field measurements, and a sample set is established based on the numerical simulation results. Fuzzy comprehensive evaluation and a backpropagation neural network are then used to evaluate and analyze the risk level. Finally, the risk assessment system is used to evaluate the risk for Line 5 of the Hangzhou Metro in China. Based on the evaluation results, adjustments to the slurry strength, grouting pressure, and soil chamber pressure are proposed, and the risk is mitigated effectively.

A WebGIS-Based System for Urban Stormwater Risk Analysis Using a Cloud Matter-Element Model

2020 ◽  
Vol 16 (3) ◽  
pp. 80-99
Author(s):  
Junfei Chen ◽  
Cong Yu
Keyword(s):  
Risk Assessment ◽  
Risk Analysis ◽  
Temporal Distribution ◽  
Element Model ◽  
Economic Loss ◽  
Risk Level ◽  
Urban Stormwater ◽  
Intelligence System ◽  
Prototype Development ◽  
Matter Element Model

The interaction of human activity, climate change, and urbanization gives rise to more frequent urban stormwater disasters, which causes great economic loss in cities. This article presents a prototype of an interactive WebGIS system for urban stormwater risk analysis. The system has a Browse/Server(B/S) structure and uses WebGIS techniques for prototype development. It is based on the theory of disaster system and Cloud matter-element model for risk assessment. The risk results are immediately generated and visualized interactively by rendering risk maps. Finally, two urban stormwater events in Nanjing in 2015 and 2016 were selected to verify the accuracy of the risk assessment. The results show that the intelligence system can effectively assess the risk level and identify the spatial-temporal distribution of urban stormwater risk in Nanjing, China.

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