48 research outputs found
Modelling and Estimating Gasoline Demand Using AIDS for Urban Low-Income Groups
One of the biggest problems facing humanity today is the shortage of non-renewable groundwater resources. Since these resources have fewer alternatives, the onlyway to survive these resources is optimal utilization of them. The purpose ofthis study is to estimate the gasoline demand in urban low-income groups. Instead of a single equation of gasoline demand, demand is modelled as a multi-equation demand system. For this purpose, a low-income group is considered for which the AIDS is estimated and assumptions are reviewed. In this research, the demand for commodities of low-income group is investigated within urban households in Iran. Using time series data relating to 1991-2009 and AIDS equations, equations of commodity consumption expenditure were estimated using seemingly unrelated regressions. The results indicate that the gasoline is a luxury commodity for low-incomegroups. In addition, gasoline is a low attractive commodity for this group
Understanding the role of décollement thickness on the evolution of décollement folds: insights from discrete element models
We explored the influence of a variety of geometric and mechanical factors in the evolution of décollement folds above a weak décollement level in a sedimentary sequence. Under an applied overburden pressure, we construct nine discrete element models (DE-models) to test the effects of mechanical stratigraphy, the thickness of the décollement layer, and the number of strong and weak layers within the sedimentary cover sequence. The effects of the aforementioned parameters on the structural style of fold belts and the mechanical evolution of décollement folds that develop during a progressive deformation are what we are searching for. The one-way lateral motion of a rigid, vertical boundary wall was used to shorten the particle assemblage. The models presented in this study were then compared to a natural structure in Iran and demonstrated that the combined effects of mechanical behaviour, the thickness of décollement layer, and the number of strong and weak layers within the sedimentary cover sequence are playing the decisive role in the structural style, kinematic and mechanical evolution of décollement folds
Understanding the role of décollement thickness on the evolution of décollement folds: insights from discrete element models
We explored the influence of a variety of geometric and mechanical factors in the evolution of décollement folds above a weak décollement level in a sedimentary sequence. Under an applied overburden pressure, we construct nine discrete element models (DE-models) to test the effects of mechanical stratigraphy, the thickness of the décollement layer, and the number of strong and weak layers within the sedimentary cover sequence. The effects of the aforementioned parameters on the structural style of fold belts and the mechanical evolution of décollement folds that develop during a progressive deformation are what we are searching for. The one-way lateral motion of a rigid, vertical boundary wall was used to shorten the particle assemblage. The models presented in this study were then compared to a natural structure in Iran and demonstrated that the combined effects of mechanical behaviour, the thickness of décollement layer, and the number of strong and weak layers within the sedimentary cover sequence are playing the decisive role in the structural style, kinematic and mechanical evolution of décollement folds
Influence of multiple décollement and cover rock rheology on the structural evolution of thin-skinned fold-and-thrust belts: insights from discrete element modelling
The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Bahregansar anticline, western Persian Gulf, Iran
Basement-involved fault geometry and kinematics has a systematic effect on the structural style of the tectonic setting. In this study, 2D and 3D seismic datasets, well data as well as thickness and depth maps were utilized to consider and reconstruct the characteristics and effects of the wrench-dominated basement-involved fault underlying the Bahregansar anticline, which is a gentle, elongated and NW–SE-trending structure in the NW Persian Gulf, on the nature of its folded strata. Moreover, using the 2D sequential restoration, the deformation of the basement structural features was modelled and analysed for its influence on the reactivation of faulting. The results show that the major basement-involved fault, called the Hendijan–Bahregansar–Nowrooz Fault (HBNF), extends along the NE–SW-trending orientation and consist of several key anticlines. The structural evolution of the Bahregansar anticline has been deeply affected by Turonian folding phase and Pliocene Zagros orogeny associated with the HBNF. In the Upper Cretaceous, the HBNF propagated upward through the overlying sedimentary sequences when the inherited normal fault contractionally reactivated in the sinistral-reverse sense as the transpression zone in response to the Neo-Tethys oceanic plate subduction under the Eurasian plate. In this regard, the NNE–SSW-trending Bahregansar anticline (i.e., Arabian trend) formed as a forced fold. Continuing oblique convergence and associated deformation was accommodated by a change in the HBNF displacement sense from sinistral to dextral movement and buckling of the Bahregansar anticline as a result of the Pliocene Zagros orogeny
The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Bahregansar anticline, western Persian Gulf, Iran
Basement-involved fault geometry and kinematics has a systematic effect on the structural style of the tectonic setting. In this study, 2D and 3D seismic datasets, well data as well as thickness and depth maps were utilized to consider and reconstruct the characteristics and effects of the wrench-dominated basement-involved fault underlying the Bahregansar anticline, which is a gentle, elongated and NW–SE-trending structure in the NW Persian Gulf, on the nature of its folded strata. Moreover, using the 2D sequential restoration, the deformation of the basement structural features was modelled and analysed for its influence on the reactivation of faulting. The results show that the major basement-involved fault, called the Hendijan–Bahregansar–Nowrooz Fault (HBNF), extends along the NE–SW-trending orientation and consist of several key anticlines. The structural evolution of the Bahregansar anticline has been deeply affected by Turonian folding phase and Pliocene Zagros orogeny associated with the HBNF. In the Upper Cretaceous, the HBNF propagated upward through the overlying sedimentary sequences when the inherited normal fault contractionally reactivated in the sinistral-reverse sense as the transpression zone in response to the Neo-Tethys oceanic plate subduction under the Eurasian plate. In this regard, the NNE–SSW-trending Bahregansar anticline (i.e., Arabian trend) formed as a forced fold. Continuing oblique convergence and associated deformation was accommodated by a change in the HBNF displacement sense from sinistral to dextral movement and buckling of the Bahregansar anticline as a result of the Pliocene Zagros orogeny
Stress and strain evolution in fault-related folds: insights from 2D geomechanical modelling
Fault-related folds are intriguing geological structures that develop in compressional and extensional regimes. These folds serve as structural traps for hydrocarbon resources, making their numerical models crucial for understanding the stress and strain evolution of hydrocarbon reservoirs. In our research, we utilize the two-dimensional finite element technique to simulate three representative categories of fault-related folds. Our investigation encompasses their geometric transformation over time, the distribution of stress and strain, variations in slip and uplift, and the effects that various mechanical properties have on these gradients. In our study, we uncovered essential findings about the behavior of fault-related folds. We ascertained that the fault slip gradient in the fault-bend fold model is less than in the fault-propagation fold model. Regarding the uplift gradient, the fault-propagation and fault-bend fold models displayed the greatest and the least degree of change, respectively. The trend of stress-strain evolution on the fold surface in all models was consistent, starting with an increase, transitioning to a constant phase, and ending with a decrease. This pattern proved to be more intricate and divergent than what was evident on the fault surface. Importantly, the internal friction angle, a crucial mechanical characteristic, had a significant influence on the development of these structures. This angle affected both the degree of uplift and stress; an increased angle resulted in enhanced uplift and stress, while a decrease resulted in a decline. Furthermore, the internal friction angle determined the compactness of the fold and the thickness of the forelimb, the part of the fold that inclines towards the advancing direction. These findings have enriched our knowledge of fault-related folds, highlighting the need to consider mechanical properties when studying their formation and evolution
Prediction of Flyrock in Boulder Blasting by Using Artificial Neural Network
ABSTRACT Rock mass is blasted to break it into smaller pieces such as in most surface mining, quarrying operation, dimensional stone mining and some civil engineering application. Flyrock is one of the most hazardous side effects of blasting operation in surface mining. This phenomenon can be considered as the main cause of casualties and damages. The aim of this study is to compare the actual distance of flyrock with the prediction suggested by empirical methods and by using Artificial Neural Network. In addition, this study is also aimed to investigate the most significant input parameters that affecting the flyrock. During this study, flyrock projections for 16 granitic boulders were monitored at Ulu Tiram-quarry site. Blasting parameters such as amount of explosive used, burden, stemming, hole depth, hole angle and hole diameter were carefully measured and recorded. By using these data and applying MATLAB (Matrix Laboratory) program (neural network toolbox), the flyrock distances were predicted for similar condition. The result shows that the coefficient of correlation between the actual and the predicted flyrock distance based on empirical methods is insignificant that is around 0.2. However the result revealed that the coefficient of correlation for overall analysis of flyrock distance is 0.92 based on ANN method. Based on Max-Min method powder factor, stemming and charge length are the most significant parameters in controlling the flyrock distance. This study found that ANN method produced a more accurate prediction than the empirical methods in assessing the actual flyrock projection
Elucidating fault-related fold mechanics: a 2D finite element analysis of bending, slip, and buckling mechanisms
Fault-related folds are present in most tectonic settings and may serve as structural traps for hydrocarbons. Due to their economic importance, many kinematic models present for them. Unfortunately, most of them have predominantly concentrated on the sliding mechanism parallel to the layering and often ignore the integral role of buckling in folding processes. This study is at the forefront of exploring the interplay among, sliding, buckling, and bending in the formation of the three fundamental types of fault-related folds: detachment, fault-propagation, and fault-bend folds. To this end, we developed five sets of two-dimensional (2D) finite element models, embodying both elastic and elasticplastic behaviors. Our results indicate that sliding parallel to layering and faults, in conjunction with buckling, are the predominant mechanisms in fault-related folding. The strain ellipse patterns in our models are consistent with those observed in buckling models, thus affirming the significance of buckling in these geological structures. Furthermore, our models demonstrate that fault slip diminishes from the periphery towards the center in all three types of fault-related folds, in contrast to interlayer slip, which intensifies from the edge towards the center. In essence, a diminution in fault slip at the center is balanced by an augmentation in interlayer slip, leading to thickening and buckling. The genesis of all three fault-related fold types is attributed to the reduction in fault slip, with their distinctiveness defined by the location of this reduction: at the detachment fault tip for detachment folds, at the ramp tip for faultpropagation folds, and at the upper flat for fault-bend folds
Minimal Dose of Tranexamic Acid Is Effective in Reducing Blood Loss in Complex Spine Surgeries: A Randomized Double-Blind Placebo Controlled Study
Study Design A randomized double-blind placebo controlled study. Purpose In the present study, we aimed to assess the efficacy of tranexamic acid (TXA) in reducing blood loss after laminectomy and posterolateral fusion of the spine. Overview of Literature Blood loss is the most significant complication involved with surgery, especially in spinal surgery. Multilevel laminectomy and laminectomy with instrumentation (pedicle screws and rods) are complex spine surgeries and are considered as medium-risk procedures for bleeding. Recent reports have demonstrated that the use of antifibrinolytic drugs during surgery may reduce the risk of postoperative bleeding and one of the most frequently used antifibrinolytics is TXA. Methods In this randomized clinical trial, 50 patients eligible for laminectomy (for ≥2 level) with postero-lateral fusion with a pedicular screw (laminectomy and posterior spinal fusion) were randomly assigned to receive preoperative single doses of intravenous TXA (15 mg/kg) or 0.9% normal saline. Results Of the 50 patients, 30 (60%) were female and 20 (40%) were male. Between-group difference with respect to the total volume of blood loss during surgery was statistically significant. Conclusions The findings of this study suggest that TXA can reduce both intraoperative and immediate postoperative blood loss, decrease the need for packed cell transfusion, and reduce the duration of hospitalization after complex spinal surgeries. No adverse events related to the use of TXA were encountered in this study