99 research outputs found
Parallel Framework for Complex Reservoir Simulation with AdvancedDiscretization and Linearization Schemes
No full textThe continuous progress of reservoir monitoring technology provides encouraging capacities to reduceuncertainties in the subsurface characterization and to mitigate risks in field development applying thereservoir simulation approach. However, it is always challenging to take full advantage of the observationdata, since an accurate representation of strong heterogeneities requires a high-resolution grid. Most ofthe discretization methods cannot handle full tensor permeability, and high nonlinearity introduced bycomplex physical process drastically reduces simulation efficiency. In this work, we develop an advancedparallel framework for reservoir simulation with the implementation of state of the art discretizationand linearization methods. We apply the multipoint flux approximation (MPFA) method to handle thefull tensor permeability in unstructured grids. To keep the fidelity of the geological model and improvecomputational efficiency, we use massively parallel computations via Message Passing Interface (MPI).Complex subsurface physics is described by mass-based formulations making the framework flexible forgeneral-purpose reservoir simulation. However, the representation of phase behavior introduces additionalworkload when compared with the phase-based formulations in the traditional approach. Here, we apply theOperator-Based Linearization (OBL) approach which not only overcomes this drawback but also turns it toan advantage. In this method, the conservation equations are described in an operator form. By constructinga library of tabulated operators, the repeated work spent on complex phase behavior and property evaluationcan be significantly reduced. We benchmark the parallel framework with analytical solutions under single-phase flow and multiphase flow. The results demonstrate that the parallel framework provides accuratesimulation results for structured and unstructured grids. We validate that MPFA implemented in our parallelframework converges to real solutions when the permeability is a full tensor. Besides, several realisticcases have been rigorously tested confirming high computational capacity, efficiency, and accuracy of theadvanced massively parallel framework for general-purpose reservoir simulation. With the implementationof MPFA and OBL approaches, the parallel framework is fully equipped for the simulation of problemswith full tensor permeability, high-heterogeneities, and complex physical processes.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Reservoir Engineerin
Neuropharmacological investigations into the mechanisms of motion sickness in Suncus murinus (house musk shrew)
No full textPh.D.Motion sickness can be debilitating and can severely impact on a susceptible individual’s quality of life, which often occurs under a variety of circumstances and is common in the general population. Antihistamines are used in the treatment of motion sickness, but they also are well known to weakly block muscarinic receptors that may contribute to unwanted side effects, and the precise mechanism of action is unknown.In the first part of the thesis, we used Suncus murinus to investigate the anti-emetic potential of highly selective brain-penetrating histamine H1 receptor antagonist, mepyramine in comparison with the non-brain-penetrating histamine H1 receptor antagonist, cetirizine; the muscarinic receptor antagonist, scopolamine was used as a positive control. Motion (1 Hz, 4 cm displacement, 10 min) induced emesis (8.4 ± 0.6 episodes), reduced sniffing activity (p < 0.001) and increased scratching activity (p < 0.001). Mepyramine (50 mg/kg, i.p.) and scopolamine (10 mg/kg, i.p.), but not cetirizine (10 mg/kg, i.p.) significantly antagonized motion-induced emesis. The short duration of motion failed to induce quantifiable c-fos expression in area postrema, nucleus tractus solitaries, medial vestibular nucleus and hypothalamus. However, mepyramine with or without motion stimulus, but not cetirizine or scopolamine, caused significant increase in c-fos expression in the brain. The mepyramine-treated animals were also sedated, and had fewer episodes of scratching during the motion test (p < 0.001).Hypothermic responses accompany motion sickness in humans and could be elicited by provocative motion in rats and Suncus murinus. Therefore, the second part of the thesis was to test whether similar responses are also present in mice, and to determine potential role of efferent cholinergic vestibular innervation in these responses. To this end, we used knockout (KO) mice lacking a9 cholinoreceptor subunit predominantly expressed in the vestibular hair cells and CBA strain as a wild-type (WT) controls. In WT mice, circular horizontal motion (1 Hz, 4 cm radius, 20 min) caused rapid and dramatic fall in core body temperature and surface head temperature associated with transient rise in the tail temperature; these responses were substantially attenuated in KO mice; changes were (WT vs KO): for the core body temperature -5.2 ± 0.3 vs -2.9 ± 0.3 ºC (p < 0.01); for the head skin temperature -3.3 ± 0.2 vs -1.7 ± 0.2 ºC (p < 0.01); for the tail skin temperature +3.9 ± 1.1 vs +1.1 ± 1.2 ºC (p < 0.01). Subsequently, the potential role of a9 AChRs in motion-induced emesis in Suncus murinus was investigated using a highly selective antagonist a-conotoxin Vc1.1. A low dose of Vc1.1 (1 µg/kg, s.c.) significantly reduced motion-induced emesis, while higher doses (10 µg/kg and 100 µg/kg) failed. However, the anti-emetic mechanism of Vc1.1 appeared to be independent of thermoregulation.Ghrelin could antagonize cisplatin-induced emesis in ferret via the actions in the brain but the mechanism is essentially unknown. Therefore, anti-emetic potential of ghrelin mimetics HM01 (brain-penetrating) and HM02 (less-brain-penetrating) were investigated in Suncus murinus. HM01 (10 mg/kg, p.o.), but not HM02 (30 mg/kg, p.o.) antagonized motion-induced emesis. Moreover, both HM01 and HM02 also caused hypothermia and induced c-fos expression in area postrema, nucleus tractus solitaries, dorsal motor nucleus of vagus, and the arcuate hypothalamic nucleus. Furthermore, both HM01 and HM02 significantly reduced motion-induced c-fos expression in medial vestibular nucleus, but did not modify burst analysis of emetic data.In conclusion, these findings suggest that centrally-located histamine H1 receptors, ghrelin growth hormone secretagogue receptors (GHS-Rs) in the brain, and a9 AChRs on the type II hair cells in the inner ear are critically involved in motion-induced emesis in Suncus murinus, and may provide a new insight into the neuropharmacological mechanisms involved in nausea and emesis control, and could potentially translate to new medicines for use in man.暈車癥，常見於不同的環境條件下發生並且嚴重影響易感人群的生活質量。舊的抗組織胺藥通常用來治療暈車症，但其同時也是毒蕈鹼性受體的弱阻斷劑，並會引起的不必要的副作用。抗組織胺藥被用於治療暈車癥，但其機制尚不清楚。本研究利用鼩鼱來研究高選擇性的腦穿透型組織胺Ⅰ型拮抗劑mepyramine，和非腦穿透型組織胺拮抗劑cetirizine的止吐作用，並以毒蕈鹼受體拮抗劑scopolamine為陽性對照。搖動（1赫茲，4釐米幅度，10分鐘）引起嘔吐（8.4±0.6次），同時減少嗅覺活動（p<0.001）和增加刮擦次數（p<0.001）。只有mepyramine和scopolamine，但不是cetirizine，明顯抑制搖動引起的嘔吐。10分鐘的擺動並不會引起腦內c-fos蛋白的表達。但是mepyramine，而不是cetirizine或者scopolamine，會引發腦中大量c-fos蛋白的表達。Mepyramine會引發動物的鎮靜效應，並且明顯減少刮擦的次數（p<0.001）。本研究室曾報道在貂腦內注射ghrelin可以成功抑制cisplatin引起的嘔吐，但其機制尚不清楚。本課題利用鼩鼱來研究ghrelin類似物腦穿透型HM01和非腦穿透型HM02的止吐效果。研究表明，只有腦穿透的HM01，而不是和非腦穿透的HM02的可以明顯抑制搖動引起的嘔吐。同時，腦穿透的HM01會引體溫降低和起腦內大量c-fos蛋白的大量表達，並且抑制搖動引起在內測前庭核c-fos蛋白的表達。在人和大鼠中，低溫反應常常伴隨著由搖動引起的暈車癥出現。本實驗研究了在暈車過程中是否小鼠也會出現類似的反應，以及輸出膽鹼能前庭神經在暈車發生過程中的潛在作用。前庭毛細胞中a9膽鹼受體亞基的敲除小鼠和野生型的小鼠被用於本實驗中。在野生型小鼠中，搖動會引起小鼠體溫和大腦表皮體溫的大量而迅速的降低，同時還有尾巴溫度的短暫而劇烈的升高。這些溫度反應在基因敲除的小鼠中明顯減弱了。變化(野生型對比敲除型小鼠):體溫-5.2±0.3vs-2.9±0.3ºC（p<0.01）；大腦表皮體溫-3.3±0.2vs.-1.7±0.2ºC（p<0.01）;尾巴溫度+3.9±1.1vs+1.1±1.2ºC（p<0.01）。接著，使用了a9膽鹼受體拮抗劑Vc1.1研究了a9膽鹼受體在鼩鼱中由搖動引起的嘔吐中作用。研究結果顯示只有低濃度的Vc1.1可以明顯止吐，而高濃度的卻不能止吐。其止吐機制可能和熱調控無關。總之，搖動引起的嘔吐和一系列的變化相關，其涉及到動物行為的改變，胃腸道蠕動的失律，體溫降低和呼吸功能的紊亂，以及腦內c-fos蛋白的大量表達。此外，首次發現了位於中樞系統的組織胺H1受體，大腦中的生長激素生長激素促分泌素受體，以及前庭中毛細胞表面的a9膽鹼受體均在由搖動引起的嘔吐中發揮重要的作用。這三個新發現的受體可能為將來產業研發新的暈車藥提供了新的靶點支持。Tu, Longlong.Thesis Ph.D. Chinese University of Hong Kong 2017.Includes bibliographical references (leaves 174-190).Abstracts also in Chinese.Title from PDF title page (viewed on 21, October, 2019)
Research on the Parameter Prediction Model for Fully Mechanized Mining Equipment Selection Based on RF-WOA-XGBoost
No full textFully mechanized mining equipment is core to the coal mining process. The selection process for this type of equipment is complex and heavily relies on experts’ experience for determining equipment parameters. This paper proposes a fully mechanized mining equipment parameter prediction model based on Extreme Gradient Boosting Regression Trees (XGBoost), which is developed based on the mapping relationships among geological parameters, fully mechanized mining face conditions, and the parameters of fully mechanized mining equipment. Feature selection is performed based on the feature importance ranking obtained through the Random Forest (RF) method, thereby reducing the model complexity. Different optimization algorithms are used to optimize the hyperparameters of XGBoost, and the results show that the Whale Optimization Algorithm (WOA) outperforms other algorithms in terms of convergence speed and optimization effectiveness. By comparing different prediction algorithms, it is found that the WOA-XGBoost model achieves higher prediction accuracy on the test set, with an average absolute error of 0.0458, root mean square error of 0.1610, and a coefficient of determination (R2) of 0.9451. Finally, a RF-WOA-XGBoost-based parameter prediction model for fully mechanized mining equipment is established, which is suitable for lightly inclined mining faces. This model reduces input complexity, improves the selection speed, minimizes reliance on experts, and ensures prediction accuracy, providing an effective reference for the parameter selection of fully mechanized mining equipment
Settlement Prediction of High Fill Subgrade in Loess Areas Based on Variational Mode Decomposition and Particle Swarm Optimization of Long Short-Term Memory Networks
No full text[Purposes] This research is conducted to achieve accurate prediction of settlement trends for high fill subgrades in loess areas. [Methods] In this work, a Variational Mode Decomposition (VMD) and Particle Swarm Optimization (PSO) optimized Long Short-Term Memory (LSTM) network prediction model was proposed, referred to as VMD-PSO-LSTM model. This model was designed to learn high-level features of the settlement data for high fill subgrade and predict their developmental trends. To validate the effectiveness of the proposed model, an engineering case study was conducted. [Results] The results clearly indicate that the VMD-PSO-LSTM model performs well in predicting the settlement curves of high fill subgrade. Moreover, its accuracy surpasses that of the Back Propagation Neural Network (BP) model, the standard LSTM model, and the LSTM model optimized solely by PSO (PSO-LSTM), suggestings that the proposed VMD-PSO-LSTM model not only provides enhanced predictive accuracy but also demonstrates increased robustness and wider applicability
A Discrete Hybrid Invasive Weed Optimization Algorithm for the Capacitated Vehicle Routing Problem
No full textAbstractThe capacitated vehicle routing problem (CVRP) has been proved to be NP complete problem. The CVRP is not just a purely academic construct, it has many applications in practice. In this work, a discrete invasive weed optimization algorithm (DIWO) is proposed to solve the capacitated vehicle routing problem. Adaptive mutation and crossover in the genetic operation process are introduced to ensure the diversity of the algorithm and prevent it from falling into a local optimal solution with premature convergence. We use real matrix encoding and construct a discretization process for the subgeneration in the parent generation region. An improved 2-Opt and exchange operations structure based on the property of the problem is proposed to construct the two-stage hybrid variable-domain search method, strengthening the capacity of the local and global search ability of the algorithms. Comparing the experimental simulation and the algorithm with literature for different scale benchmarks proves that the DIWO algorithm is simple, efficient, adaptable, and robust for discrete combinatorial optimization problems
Research on adsorption of Cr(Ⅵ) by Poly-epichlorohydrin-dimethylamine (EPIDMA) modified weakly basic anion exchange resin D301
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Enhanced phosphorus and ciprofloxacin removal in a modified BAF system by configuring Fe-C micro electrolysis: Investigation on pollutants removal and degradation mechanisms
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