Tree Analysis Approach Research Articles

Subcutaneous glucose biosensor failure – a fuzzy fault tree analysis approach

Diabetes mellitus is a disease of major global importance, increasing in frequency at almost epidemic rates. In order to optimize diabetes management and, therefore, reduce hyper- or hypo-glycaemia complications, continuous and reliable in vivo (subcutaneous or intravenous) glucose monitoring is indispensable. To that end, subcutaneous sensors have progressed more rapidly as they can be linked to state-of-the-art signal transmission modes (transdermal, IR, etc.). Yet, most of the devices currently at clinical trials have not demonstrated a stable and clinically useful sensor performance. In this work, the causes of subcutaneous glucose biosensor sensitivity drift have been investigated by means of fault tree analysis relying on fuzzy reasoning to account for uncertainty. Using the methodology proposed herein, all ultimate causes or combination of causes attributed to the device components, the surrounding tissue and their intra/inter-relations that are responsible for or contribute to the top event have been recognized and quantifi ed based on (a) measurements for the deterministic contributors and (b) experience for the stochastic contributors. The tree structure has been designed by combining deduction and induction, top-down and bottom-up techniques, thus establishing a dialectic tradeoff which brings this method closer to scientifi c logic, permitting the introduction of deeper knowledge into the surface or experiential knowledge level characterizing FTA. The proposed methodology has been implemented in the investigation of the causes responsible for sensor fouling by thrombus formation and has proven to be an effi cient tool for internal diagnostics and fault compensation. The suggested approach may contribute signifi cantly to the self-optimization of the measuring equipment from one generation to the next as it supports the fl exible, ad hoc, and tailor-made development, thus potentiating the progress of epidemics from statistics to individualization.

A new fault tree analysis approach based on imprecise reliability model

Fault tree analysis is a powerful and computationally efficient technique for safety analysis and reliability prediction. It decomposes an undesired failure into multiple possible root causes by constructing a sub-event tree and spreading it into basic events. Classical reliability theory using probability theory to quantify the uncertainties of basic events encounters many challenges when failure data are limited. In this case, uncertainty quantification should be carried out based on subjective information, such as experts’ assessment or engineers’ experience. As a generalization of probability theory, imprecise probability theory can quantify subjective information as the upper and lower expectations or previsions. In this article, a fault tree analysis algorithm incorporating subjective information into imprecise reliability models of basic events is proposed to calculate the failure interval of lubricating oil warning system.

Risk assessment for enterprise resource planning (ERP) system implementations: a fault tree analysis approach

Enterprise resource planning (ERP) system implementations are often characterised with large capital outlay, long implementation duration, and high risk of failure. In order to avoid ERP implementation failure and realise the benefits of the system, sound risk management is the key. This paper proposes a probabilistic risk assessment approach for ERP system implementation projects based on fault tree analysis, which models the relationship between ERP system components and specific risk factors. Unlike traditional risk management approaches that have been mostly focused on meeting project budget and schedule objectives, the proposed approach intends to address the risks that may cause ERP system usage failure. The approach can be used to identify the root causes of ERP system implementation usage failure and quantify the impact of critical component failures or critical risk events in the implementation process.

Quantitative safety analysis of a laboratory‐scale bioreactor for hydrogen sulfide biotreatment using fault tree analysis

Numerous research activities are conducted all over the world to study biological treatment of H2S in laboratory‐scale bioreactors. Important hazards associated with these bioreactor systems include the escape of H2S gas and leakage of chemical/biological liquids, which have severe adverse effects on the involved labors, equipment, and materials. The objective of this article is to present a quantitative safety analysis of a laboratory‐scale continuous bioreactor system for H2S gas biotreatment using the fault tree analysis approach. Three unwanted top events were determined as the most hazardous events, being H2S leakage inside the laboratory, H2S leakage to outdoor from bioreactor outlet, and leakage of liquid chemical/biological solutions. The minimal cut sets and the probability of the occurrence of each top event were determined. The importance of cut sets and basic events were calculated, and priorities for control measures were determined. The analysis allows better decision on priority of control measures, and maintenance or replacement schemes of the system components in an endeavor to minimize the probability of failure or hazard occurrence. The presented analysis proves the usefulness of fault tree analysis in making quantitative risk assessment and safety analysis, which are important elements in laboratory safety management system. © 2013 American Institute of Chemical Engineers Process Saf Prog 32: 376–386, 2013

Brain metastases during follow‐up of children and adolescents with extracranial malignant germ cell tumors: Risk adapted management decision tree analysis based on data of the MAHO/MAKEI‐registry

The overall risk for brain metastases among children and adolescents with extracranial malignant germ cell tumors (mGCT) is low but may vary between subgroups. Early identification of subgroups with an increased risk for brain metastasis is therefore important. We analyzed 900/2,160 patients from the German MAHO/MAKEI registry on children and adolescents with malignant extracranial GCT (pure teratomas (grade 0-3) were not included). For follow-up evaluation, patients with brain metastases at diagnosis and those with a follow-up shorter than 32 months after diagnosis (longest interval to brain metastases in our cohort) were excluded. Patients were censored at detection of brain metastases or death due to other causes. A decision tree analysis considering age, gender, site of primary tumor, and presence of other metastases at diagnosis as risk factors for brain metastases was performed. Among 838 eligible patients, 9 acquired brain metastases during follow-up, accounting for death in 5. There were no brain metastases in absence of extracranial metastases at diagnosis. If extracranial metastases were detected in absence of mediastinal mGCT the risk for brain metastases was 1.2% (95% CI: 0.2-3.5.%). In contrast, risk was increased to 37.5 (95% CI 15.2-64.6%) in patients with mediastinal GCTs and extracranial metastases. A high-risk subgroup is detected with a decision tree analysis approach. These patients may benefit from an intensified chemotherapy. Close surveillance for CNS-metastases is warranted in this high-risk group while less close monitoring in low-risk patients is justified. Pediatr Blood Cancer 2013;60:217-223. © 2012 Wiley Periodicals, Inc.

Fuzzy Reliability Evaluation of a Fire Detector System

Reliability has vital significance to engineers and designers in a safety system. Consequently, failures free operation of components or sub-systems is of their key concern. To assess the reliability of such systems quantitatively, failure data of the components or sub-systems is essentially required. In general, such data is either not pre-recorded or present in linguistic form (good, bad etc). For quantitative evaluation of reliability the usual probabilistic considerations seems to be inadequate. Therefore, in this paper, conventional fault tree analysis (FTA) approach integrated with fuzzy theory has been used to evaluate the reliability of a fire detector system using fuzzy failure possibilities of components (or subsystems).

Participation, self-concept and motor performance of boys with developmental coordination disorder: A classification and regression tree analysis approach

Identification of relationships between participation, psycho-social adjustment and motor performance factors in boys with developmental coordination (DCD) using a classification and regression tree approach to determine patterns of potential vulnerability. A quantitative cross-sectional design investigating a cohort of 60 boys aged 10-13 years with DCD was employed. Classification and regression tree analysis of: (i) fundamental movement skill performance on tests of balance, ball skills and manual dexterity, (ii) self-concept perceptions and (iii) leisure-time activity participation, was used to define different risk groups. Five meaningful groups of boys were identified. Poor manual dexterity was the strongest discriminator of group membership in the three most severely affected groups confirming the significance of fine motor difficulties as a key grouping variable and supporting previous research using cluster analyses. Low participation in out-of-school informal social-physical activities was found to be a new grouping factor alongside poor peer relations self-concept. A final group describing boys with poor motor performance across all fundamental movement skill areas who had high participation in structured social non-physical activities, such as choir or band, was identified. The potential for future classification and regression tree analyses to inform clinical decision making was discussed.

Decision tree analysis and real options: a reconciliation

The purpose of this paper is to demonstrate in a simple framework how decision tree analysis (DTA) and real options approach (ROA) yield the same results when markets are complete. The common scepticism regarding DTA has its roots in the incorrect assumption that one can apply the same discount rate to the project cash flows and the value of the investment opportunity when the decision maker has the option to defer investment. Copyright © 2011 John Wiley & Sons, Ltd.

Using SeaWiFS and In Situ Data for HAB Prediction in the Northern Gulf of Mexico: Decision Tree Analysis

AbstractTo date, 13 potential HAB species have been detected in coastal waters of Mississippi and Alabama, including representatives of the diatom genera Pseudo-nitzschia and Chaetoceros, and dinoflagellate genera Karenia, Gonyaulax, Akashiwo, Karlodinium, and Prorocentrum. This study investigates the potential of satellite remote sensing (SeaWiFS) to predict environmental conditions leading to the formation of HABs in these turbid coastal waters. Phytoplankton populations and water quality were monitored in situ at 3 to 6 week intervals and 17 locations in Mobile Bay and the Mississippi Sound from December, 2004, through June, 2006. SeaWiFS imagery corresponding with in situ collections was acquired. Non-parametric multivariate analyses determined relationships between phytoplankton cell counts and in situ or satellite-derived water properties, including surface temperature, salinity, concentrations of chlorophyll, total suspended solids, colored dissolved organic material, and nutrient levels. This paper will describe an expert system decision tree analysis approach to prediction of ecological conditions necessary for the formation of HABs. The model assumes unique ranges of remote sensing reflectance ratios, Chl a, and total suspended solids must exist within the environment are conducive for the formation of HABs.

Application of fault tree analysis to the service process: service tree analysis approach

Purpose – This study aims to propose a tree‐based analytic tool that may be used in analyzing a large‐scale and complex service process. The tenet of this tool is based on the Boolean logic and named service tree analysis (STA). The proposed STA aims to reflect the customer participation perspective and to propose how to analyze the service process and deduce useful information.Design/methodology/approach – Fault tree analysis is used as an underlying methodology since it has a Boolean logic to describe the customer's selection of each element and identifies critical events. Taking these advantages of the fault tree, the proposed STA consists of three main parts; service tree construction, qualitative analysis, and quantitative analysis. First, a service tree is constructed depending on how the service elements are selected by the customer; If the subordinate events are always selected by customers, they are linked with an AND gate, otherwise, with an OR gate. Next, in the qualitative analysis, service el...

Application of the fault tree analysis for assessment of power system reliability

A new method for power system reliability analysis using the fault tree analysis approach is developed. The method is based on fault trees generated for each load point of the power system. The fault trees are related to disruption of energy delivery from generators to the specific load points. Quantitative evaluation of the fault trees, which represents a standpoint for assessment of reliability of power delivery, enables identification of the most important elements in the power system. The algorithm of the computer code, which facilitates the application of the method, has been applied to the IEEE test system. The power system reliability was assessed and the main contributors to power system reliability have been identified, both qualitatively and quantitatively.

Destination product characteristics as useful predictors for repeat visiting and recommendation segmentation variables in tourism: a CHAID exhaustive analysis

AbstractThe present paper constitutes a segmentation research with the use of the exhaustive chi‐squared automatic interaction detection tree analysis approach which, through the characteristics of a tourist destination, aims at the illustration of the English and German tourist groups and more specifically, (i) those who are repeat visitors of several tourist destinations and (ii) those who express a willingness to urge other people to visit geographic tourist destinations that the former have already visited. The results of the research help the tourism managers to apprehend the characteristics of the destination products that best describe the visitors. Copyright © 2008 John Wiley & Sons, Ltd.

Predictors of children in foster care being adopted: A classification tree analysis

When returning home is not a viable option, adoption is the primary means by which youth in substitute care achieve permanency. Therefore, understanding the factors that impact adoption is critical to both evaluating and improving the child welfare system. Prior research has mostly studied “main effects” in regard to adoption rates and has not explored the ways in which youth and foster family variables might interact in complex ways to predict adoption. This study uses a classification tree analysis approach known as Optimal Data Analysis (ODA) to predict probability of adoption in 2003 using Adoption and Foster Care Analysis and Reporting System (AFCARS) data. 30,000 adopted youth and 30,000 non-adopted youth were randomly selected for participation in the study. Similar to previous studies, univariate analyses revealed that age, foster parent race/ethnicity, foster parent marital status, and number of previous placements all predicted probability of adoption. However, going further, several combinations of individual variables (multivariate ODA) improved prediction accuracy (e.g., age × structure of foster family × number of previous placements). Results also suggested that the impact of the state on adoption rates varied when essentially controlling for youth and family variables, supporting concerns regarding the crude use of AFCARS data when comparing states.

An alternative approach to HACCP system implementation

The practical implementation of hazard analysis and critical control point (HACCP) and in particular the definition of the critical control points (CCPs) in the food industry is usually a complex structured task. This is particularly the case of small medium enterprise (SMEs), where quality/safety manager ability, knowledge of the production processes and “sensitiveness” is usually the discriminate for the proper identification and prioritization of risks. The same applies for the definition of causes which may lead to food safety hazards. This paper addresses the issues of how quality/safety managers can objectively and automatically implement the first and second principles of hazard analysis in the application of HACCP, which is the identification of risk priorities and of the related CCPs, by means of a structured, quantitative and qualitative methodology. The proposed methodology combines fault tree analysis (FTA) approach, for the analytical decomposition of the relevant steps in the manufacturing process of a food product, and fuzzy logic, for quantitative measures of occurrence likelihood. The practical implications of the methodology are finally tested through a real case application.

Estimation of safety distances in the vicinity of fuel gas pipelines

In this paper, safety distances around pipelines transmitting liquefied petroleum gas and pressurized natural gas are determined considering the possible outcomes of an accidental event associated with fuel gas release from pressurized transmission systems. Possible outcomes of an accidental fuel gas release were determined by performing the Event Tree Analysis approach. Safety distances were computed for two pipeline transmission systems of pressurized natural gas and liquefied petroleum gas existing in Greece using real data given by Greek Refineries and the Greek Public Gas Enterprise. The software packages chetah and breeze were used for thermochemical mixture properties estimation and quantitative consequence assessment, respectively. Safety distance determination was performed considering jet fire and gas dispersion to the lower flammable limit as the worst-case scenarios corresponding to immediate and delayed cloud ignition. The results showed that the jet fire scenario should be considered as the limiter for safety distances determination in the vicinity of natural and petroleum gas pipelines. Based on this conclusion, the obtained results were further treated to yield functional diagrams for prompt safety distance estimation. In addition, qualitative conclusions were made regarding the effect of atmospheric conditions on possible events. Thus, wind velocity was found to dominate during a jet fire event suppressing the thermal radiation effect, whereas gas dispersion was found to be affected mainly by solar radiation that favors the faster dissolution of fuel gas below the lower flammable limit.

International Staging System for Multiple Myeloma

There is a need for a simple, reliable staging system for multiple myeloma that can be applied internationally for patient classification and stratification. Clinical and laboratory data were gathered on 10,750 previously untreated symptomatic myeloma patients from 17 institutions, including sites in North America, Europe, and Asia. Potential prognostic factors were evaluated by univariate and multivariate techniques. Three modeling approaches were then explored to develop a staging system including two nontree and one tree survival assessment methodologies. Serum beta2-microglobulin (Sbeta2M), serum albumin, platelet count, serum creatinine, and age emerged as powerful predictors of survival and were then used in the tree analysis approach. A combination of Sbeta2M and serum albumin provided the simplest, most powerful and reproducible three-stage classification. This new International Staging System (ISS) was validated in the remaining patients and consists of the following stages: stage I, Sbeta2M less than 3.5 mg/L plus serum albumin > or = 3.5 g/dL (median survival, 62 months); stage II, neither stage I nor III (median survival, 44 months); and stage III, Sbeta2M > or = 5.5 mg/L (median survival, 29 months). The ISS system was further validated by demonstrating effectiveness in patients in North America, Europe, and Asia; in patients less than and > or = 65 years of age; in patients with standard therapy or autotransplantation; and in comparison with the Durie/Salmon staging system. CONCLUSION) The new ISS is simple, based on easy to use variables (Sbeta2M and serum albumin), and recommended for early adoption and widespread use.

Potential Changes in Tree Species Richness and Forest Community Types following Climate Change

Potential changes in tree species richness and forest community types were evaluated for the eastern United States according to five scenarios of future climate change resulting from a doubling of atmospheric carbon dioxide (CO2). DISTRIB, an empirical model that uses a regression tree analysis approach, was used to generate suitable habitat, or potential future distributions, of 80 common tree species for each scenario. The model assumes that the vegetation and climate are in equilibrium with no barriers to species migration. Combinations of the individual species model outcomes allowed estimates of species richness (from among the 80 species) and forest type (from simple rules) for each of 2100 counties in the eastern United States. Average species richness across all counties may increase slightly with climatic change. This increase tends to be larger as the average temperature of the climate change scenario increases. Dramatic changes in the distribution of potential forest types were modeled. All five scenarios project the extirpation of the spruce–fir forest types from New England. Outputs from only the two least severe scenarios retain aspen–birch, and they are largely reduced. Maple–beech–birch also shows a large reduction in area under all scenarios. By contrast, oak–hickory and oak–pine types were modeled to increase by 34% and 290%, respectively, averaged over the five scenarios. Although many assumptions are made, these modeled outcomes substantially agree with a limited number of predictions from researchers using paleoecological data or other models.

Analysing critical components in complex system design: a comparison of methods with the ESCAF approach

An electronic simulation approach to fault tree analysis has been developed by the French CEA in Valduc. Known as ESCAF, this system is an analogue, desk-top computer, commercialized and in use at several large companies and universities. An advantage of ESCAF to other approaches is that complex systems are analysed without resort to Monte Carlo and other complicated calculational procedures. ESCAF handles systems with up to 416 basic components, and is most applicable for system design analysis. Recently, ESCAF has been improved to quantify component/cut-set importance and to improve system design. The ESCAF method has been compared with other available fault tree analysis approaches. These studies have shown that ESCAF is able to solve problems which are very difficult to solve (if unsolvable) by other approaches, and does so rapidly and economically.

Fatigue failure models—Birnbaum-Saunders vs inverse Gaussian : G. K. Bhattacharyya and Arthur Fries. IEEE Trans. Reliab.R-31 (5), 439 (1982)

An electronic simulation approach to fault tree analysis has been developed by the French CEA in Valduc. Known as ESCAF, this system is an analogue, desk-top computer, commercialized and in use at several large companies and universities. An advantage of ESCAF to other approaches is that complex systems are analysed without resort to Monte Carlo and other complicated calculational procedures. ESCAF handles systems with up to 416 basic components, and is most applicable for system design analysis. Recently, ESCAF has been improved to quantify component/cut-set importance and to improve system design. The ESCAF method has been compared with other available fault tree analysis approaches. These studies have shown that ESCAF is able to solve problems which are very difficult to solve (if unsolvable) by other approaches, and does so rapidly and economically.