196 research outputs found
Evaluation of effects of geomechanical parameters and in-situ stress on rockburst occurrence in deep excavations
No full textThe increasing demand for natural minerals has driven underground mining to greater depths, where the challenges of maintaining excavation stability become significantly more complex. Among these challenges, rockbursts— defined as sudden and violent failures of rock—represent a critical hazard. These phenomena are driven by elevated stress conditions and strongly influenced by geomechanical parameters and in-situ stress, both of which exhibit inherent uncertainty. Despite extensive research, the mechanisms underlying rockburst occurrences remain partially understood. This thesis investigates the effects of geomechanical parameters and in-situ stress on rockburst occurrences, addressing key knowledge gaps and proposing advanced methodologies for enhanced risk evaluation in deep excavations. To address the uncertainties in geomechanical parameters, a robust three-step methodology was developed. This approach incorporates statistical data treatment techniques to ensure reliable parameter quantification, detailed analysis of schistosity effects on rock behavior, and petrographic studies to capture the influence of mineralogical compositions. This integrated approach can improve understanding of variability inherent in geomechanical properties and its implications for excavation stability. Particular emphasis was placed on reviewing outlier detection methods and selecting optimal data treatment techniques to develop reliable input parameters for predictive models. This research also conducted an in-depth characterization of in-situ stress, a crucial factor for underground excavation analysis. By combining statistical methods with geological insights, the research refined existing stress-depth relationships for the Canadian Shield. This process involved a critical evaluation of traditional approaches and the incorporation of new data to address the limitations of previous models. The resulting stress-depth relationships provide a more accurate basis for evaluating rockburst risks and form a key contribution to the field of underground rock mechanics. Employing the quantified geomechanical parameters and refined stress-depth relationships, this study systematically analyzed the applicability and limitations of existing rockburst prediction criteria. Advanced numerical simulations revealed significant variability in predictive accuracy across various indices. Criteria incorporating major principal stress, such as the Tao and Zhang indices, demonstrated better performance in identifying high-risk zones, particularly near spandrel areas and tunnel crowns. Boundary-specific assessments further highlighted the critical role of spatial variability in rockburst susceptibility, demonstrating that risks intensify with distance from the tunnel boundary and vary significantly between rock units with distinct geomechanical properties. This thesis bridges gaps in the understanding of rockburst mechanisms by integrating geological, statistical, and engineering perspectives. By addressing uncertainties associated with geomechanical parameters and in-situ stress, this study provides a comprehensive framework for predicting rockburst occurrences in deep underground projects.
RÉSUMÉ
La demande croissante en métaux et autres substances minérales a conduit l'exploitation minière souterraine à des profondeurs plus importantes, où les défis liés au maintien de la stabilité des excavations deviennent considérablement plus complexes. Parmi ces défis, les coups de terrain — définis comme des ruptures soudaines et violentes de la roche — représentent un danger majeur. Ces phénomènes sont provoqués par des conditions de contraintes élevées et sont fortement influencés par les paramètres géomécaniques et les contraintes in-situ, qui présentent tous deux une incertitude inhérente. Malgré des recherches approfondies, les mécanismes sous-jacents aux occurrences de coups de terrain demeurent partiellement compris. Cette thèse examine les effets des paramètres géomécaniques et des contraintes in-situ sur les occurrences de coups de terrain, en comblant des lacunes importantes dans les connaissances et en proposant des méthodologies avancées pour une évaluation améliorée des risques dans les excavations profondes. Pour traiter les incertitudes liées aux paramètres géomécaniques, une méthodologie robuste en trois étapes a été développée. Cette approche intègre des techniques de traitement statistique des données pour garantir une quantification fiable des paramètres, une analyse détaillée des effets de la schistosité sur le comportement de la roche, ainsi que des études pétrographiques pour saisir l'influence des compositions minéralogiques.
Cette approche intégrée permet d'améliorer la compréhension de la variabilité inhérente aux propriétés géomécaniques et de ses implications pour la stabilité des excavations. Une attention particulière a été accordée à l'examen des méthodes de détection des valeurs aberrantes et à la sélection des techniques de traitement des données optimales pour développer des paramètres d'entrée fiables pour les modèles prédictifs. Cette recherche a également mené une caractérisation approfondie des contraintes in-situ, un facteur crucial pour l'analyse des excavations souterraines. En combinant des méthodes statistiques avec des connaissances géologiques, l'étude a affiné les relations existantes contrainte-profondeur pour le Bouclier canadien. Ce processus a impliqué une évaluation critique des approches traditionnelles et l'intégration de nouvelles données pour remédier aux limites des modèles précédents. Les relations contrainte-profondeur résultantes fournissent une base plus précise pour l'évaluation des risques de coups de terrain et constituent une contribution clé au domaine de la mécanique des roches souterraines. En utilisant les paramètres géomécaniques quantifiés et les relations contrainte-profondeur affinées, cette étude a systématiquement analysé l'applicabilité et les limites des critères existants de prédiction des coups de terrain. Des simulations numériques avancées ont révélé une variabilité significative de la précision prédictive entre les différents indices. Les critères intégrant la contrainte principale majeure, tels que les indices de Tao et Zhang, ont montré de meilleures performances pour identifier les zones à haut risque, en particulier près des zones de
spandrel et des couronnes de tunnel. Les évaluations spécifiques aux frontières ont mis en évidence le rôle critique de la variabilité spatiale dans la susceptibilité aux coups de terrain, démontrant que les risques augmentent avec la distance par rapport à la paroi du tunnel et varient considérablement entre les unités rocheuses ayant des propriétés géomécaniques distinctes. Cette thèse comble les lacunes dans la compréhension des mécanismes de coups de terrain en intégrant des perspectives géologiques, statistiques et d'ingénierie. En abordant les incertitudes associées aux paramètres géomécaniques et aux contraintes in situ, cette étude fournit un cadre complet pour prédire les occurrences de coups de terrain dans les projets souterrains profonds
Erratum: Immunogenicity, antigenicity and epitope mapping of Salmonella InvH protein: An in silico study
No full textThere was an error in the author list of the published article.
Two authors (T Hashempour, Z Hasanshahi) requested to remove from the authors lists. After obtaining the agreement of the authors and the corresponding author, Editor-in-Chief accept the corrections as listed below.
The correct author list is:
Behzad Dehghani, Iraj Rasooli
We apologize for any inconvenience this may have caused.
Erratum for:
Immunogenicity, antigenicity and epitope mapping of Salmonella InvH protein: An in silico study
B Dehghani, T Hashempour, Z Hasanshahi, I Rasooli
J Curr Biomed Rep. 2020; 1(1): 9-16
Correction to:Value of 2-[18F]FDG-PET/CT in identifying immune-related adverse events in patients with melanoma or non-small cell lung cancer: a systematic scoping review (Clinical and Translational Imaging, (2024), 12, 2, (187-195), 10.1007/s40336-024-00618-3)
No full textIn this article the author name Mohammad Naghavi-Behzad was incorrectly written as Mohammad Naghavi-Bezhad. The original article has been corrected.</p
Optimizing parallel I/O performance of HPC applications
No full textParallel I/O is an essential component of modern High Performance Computing (HPC). Obtaining good I/O performance for a broad range of applications on diverse HPC platforms is a major challenge, in part because of complex inter-dependencies between I/O middleware and hardware. The parallel file system and I/O middleware layers all offer optimization parameters that can, in theory, result in better I/O performance. Unfortunately, the right combination of parameters is highly dependent on the application, HPC platform, and problem size/concurrency. Scientific application developers do not have the time or expertise to take on the substantial burden of identifying good parameters for each problem configuration. They resort to using system defaults, a choice that frequently results in poor I/O performance. We expect this problem to be compounded on exascale class machines, which will likely have a deeper software stack with hierarchically arranged hardware resources.
We present a line of solution to this problem containing an autotuning system for optimizing I/O performance, I/O performance modeling, I/O tuning, I/O kernel generation, and I/O patterns. We demonstrate the value of these solution across platforms, applications, and at scale.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2017-12-01The student, Babak Behzad, accepted the attached license on 2015-11-20 at 13:31.The student, Babak Behzad, submitted this Dissertation for approval on 2015-11-20 at 13:45.This Dissertation was approved for publication on 2015-11-23 at 13:41.DSpace SAF Submission Ingestion Package generated from Vireo submission #8816 on 2016-03-02 at 14:06:01Made available in DSpace on 2016-03-02T20:23:36Z (GMT). No. of bitstreams: 4
BEHZAD-DISSERTATION-2015.pdf: 2579773 bytes, checksum: e393f126dc8ca1229a99a983f6997d0b (MD5)
ProQuestSign-BabakBehzad.pdf: 268035 bytes, checksum: f29cad9dd3b5d70629f7fa2b72875efc (MD5)
BabakBehzad_CS_PhDThesis_Final_2015.zip: 19558300 bytes, checksum: ab9daeaa06c6144e16b86542046ac95e (MD5)
LICENSE.txt: 4209 bytes, checksum: 648e218a7b53159b5f1fbf5c97c5c231 (MD5)
Previous issue date: 2015-11-23Embargo set by: Seth Robbins for item 91322
Lift date: 2018-03-02T20:24:31Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 91322 on 2018-03-03T10:15:34Z
Competition in dual-channel supply chains: The manufacturers' channel selection
No full text© 2020 The Author(s) Innovative selling channels have brought about opportunities as well as challenges for upstream manufacturers. The past few years have witnessed both the success and failure of manufacturers with different channel strategies. To explore the rationale of different channel strategies in various contexts, we develop a model to analyze a manufacturer's channel selection decision among three channel strategies, i.e., a direct-channel strategy, a retail-channel strategy, and a dual-channel strategy consisting of both direct and retail channels. The model rests on the channel differentiation in terms of consumers’ channel preferences and operating costs of retail and direct channels. Specifically, we incorporate the action of a competitor and track down its influence on the focal manufacturer's channel preference. Our research clarifies the role of competition in the market and offers insights into the competitive nature of business in real life. Results show that the manufacturer's channel preference depends not only on the channels’ operating costs and consumers’ channel preferences but also on the competitor's channel strategy. We find that symmetric manufacturers can adopt asymmetric strategies as Nash equilibria and also that there are situations where no Nash equilibrium exists. We characterize the Nash equilibria in the channel selection game based on the exogenous parameters of the model
Review of Applicable Outlier Detection Methods to Treat Geomechanical Data
No full textThe reliability of geomechanical models and engineering designs depend heavily on high-quality data. In geomechanical projects, collecting and analyzing laboratory data is crucial in characterizing the mechanical properties of soils and rocks. However, insufficient lab data or underestimating data treatment can lead to unreliable data being used in the design stage, causing safety hazards, delays, or failures. Hence, detecting outliers or extreme values is significant for ensuring accurate geomechanical analysis. This study reviews and categorizes applicable outlier detection methods for geomechanical data into fence labeling methods and statistical tests. Using real geomechanical data, the applicability of these methods was examined based on four elements: data distribution, sensitivity to extreme values, sample size, and data skewness. The results indicated that statistical tests were less effective than fence labeling methods in detecting outliers in geomechanical data due to limitations in handling skewed data and small sample sizes. Thus, the best outlier detection method should consider this matter. Fence labeling methods, specifically, the medcouple boxplot and semi-interquartile range rule, were identified as the most accurate outlier detection methods for geomechanical data but may necessitate more advanced statistical techniques. Moreover, Tukey’s boxplot was found unsuitable for geomechanical data due to negative confidence intervals that conflicted with geomechanical principles
Cytokine-mediated FOXO3a phosphorylation suppresses FasL expression in hemopoietic cell lines: Investigations of the role of Fas in apoptosis due to cytokine starvation
No full textWe have investigated phosphatidylinositol 3-kinase (PI3K)-dependent survival signalling pathways using several cytokines in three different hemopoietic cell lines, MC/9, FDC-P1, and TF-1. Cytokines caused PI3K- and PKB-dependent phosphorylation of FOXO3a (previously known as FKHRL1) at three distinct sites. Following cytokine withdrawal or PI3K inhibition, both of which are known to lead to apoptosis, there was a loss of FOXO3a phosphorylation, and a resulting increase in forkhead transcriptional activity, along with increased expression of Fas Ligand (FasL), which could be detected at the cell surface. Concurrently, an increase in cell surface expression of Fas was also detected. Despite the presence of both FasL and Fas, there was no detectable evidence that activation of Fas-mediated apoptotic events was contributing to apoptosis resulting from cytokine starvation or inhibition of PI3K activity. Thus, inhibition of FOXO3a activity is mediated by the PI3K–PKB pathway, but regulation of FasL is not the primary means by which cell survival is regulated in cytokine-dependent hemopoietic cells. We were also able to confirm increased expression of known FOXO3a targets, Bim and p27kip1. Together, these results support the conclusion that mitochondrial-mediated signals play the major role in apoptosis of hemopoietic cells due to loss of cytokine signalling. [ABSTRACT FROM AUTHOR]Peer reviewedfinal article publishedCytokineSignal transductionapoptosisTranscription factorProtein kinas
Bilingualism, Monolingualism and Social Health: A Comparative Study Behzad Khedri , Farideh Sadat Momeni Masuole
No full textdimensions in the two groups of students in favor of bilingual students, and the variables such as age, marriage, field of study, socioeconomic status, religious beliefs and communication skills were influential on the social health of both groups. Also, the results of the regression showed that 29% of the influence on the dependent variable of this study was interpreted by the independent variables. In addition, the communication skill is the strongest variable predictor with a rate of 66%. Keyword: Social Health, Social Integration, Students, Language Bilingualism, Monolingualism and Social Health: A Comparative Study Behzad Khedri[1] , Farideh Sadat Momeni Masuole[2] Received: 18/2/2017 Accepted: 30/4/2018 Abstract There are mental influencing factors among students in the educational context such as educational stress, ethnic and cultural contradictions and the existence of political, belief, racial as well as gender discrimination, which can affect various aspects of student life and the health of this stratum, especially their social dimension could be endangered. Regarding the relationship between language, as a fundamental cultural component, and social health which has not been studied in social health research. In other words, the language of different ethnicities can provide unity, integrity, coherence and participation, or can a common language affect health and its social dimension or not? This study aims to answer the mentioned question by investigating bilingual students (ethnicities) and the monolinguals (those who speak only one language). In the following, we intend to explain what factors affect the social health of each group? The method of this study was survey and data was collected through questionnaires. The statistical population is Sanandaj University students and the sample included 384 individuals by the Cochran formula. The results of this study showed that there is a significant difference between the total social health and its [1]. PhD Student of Social Work, AllamehTabatabaiiUniversity, Tehran. (Corresponding Author). [email protected] [2]. Master of Sociology, ShahedUniversity. [email protected]
- …
