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نتیجه جستجو - Flow pattern

تعداد مقالات یافته شده: 11
ردیف عنوان نوع
1 A new wellbore fluid load diagnosing model based on the energy conservation law
یک مدل تشخیصی بار مایع چاه جدید بر اساس قانون حفظ انرژی-2020
Liquid load in the borehole would affect the rate stability of gas well adversely. However, the existing liquid load detection techniques are somewhat limited by practical application. For the purpose of clarifying the liquid-carrying mechanism of two-phase flow in the wellbore with a higher liquid rate, it is necessary to accurately diagnose the presence of liquid loading in the wellbore and reasonably formulate the production measures of the gas well. On the basis of previous studies, this paper established a new model for diagnosing the liquid-carrying conditions of gaseliquid two-phase vertical pipe flow according to the law of energy conservation. Then, by comparing with field practice statistics and indoor experimental data, the accuracy of the new model was verified. Finally, the new model was applied to analyze the liquid-carrying condition of one certain liquid-producing gas well. And the following research results were obtained. First, when the liquid production rate is lower, the critical liquid-carrying gas rate calculated by the new model is much lower than the calculation result of the Turner model. Second, with the increase of the liquid production rate, the critical liquid-carrying gas rate calculated by the new model increases gradually. And the higher the pressure is, the more obvious the increase of the critical liquid-carrying gas rate is. Third, from the perspective of flow pattern, the gaseliquid two-phase vertical pipe flow can be divided into 5 kinds, including bubble flow, slug flow, transition flow, wavy flow and annular mist flow. When the two-phase flow is transition flow, wavy flow or annular mist flow, there is no liquid loading in the wellbore. In conclusion, the calculation result of the new model is basically accordant with field practice statistics and indoor experimental data, and its diagnostic conclusion conforms to the actual situations. Obviously, this model is of universality and provides a theoretical support for the diagnosis of liquid-carrying condition and the prevention of fluid loading in liquid-producing gas wells.
Keywords: Liquid-producing gas well | Liquid carrying mechanism | Flow pattern | Wellbore | Diagnosis on liquid loading | Critical liquid-carrying gas rate | Energy conservation
مقاله انگلیسی
2 Search strategies at the European Patent Office
راهکارهای جستجو در اداره ثبت اختراعات اروپا-2020
Prior-art search is a critical step towards determining whether a patent can be granted or not. In 2016, an internal project called Search Workflow Modelling (SWM) was launched at the European Patent Office (EPO) for building a search knowledgebase, which contains a set of models that record not only the current situation on how patent examiners deal with prior-art search (i.e. the as-is models), but also their requirements of being able to do a more efficient and effective search (i.e. the to-be models). We use the Fact-based Modelling (FBM) approach for formalizing search ontologies, which cover a common vocabulary, relations between concepts related to search, and constraints applicable to these relations. We use a hybrid modelling approach of Business Process Modelling Notations and Case Management Model and Notations (BPMN/CMMN) to model search work flows. A patent search strategy typically involves at least one FBM model and at least one BPMN/CMMN model. In this paper, we will illustrate 5 types of existing search strategies (including recursive flow patterns and FBM models for future search features), and future search strategies. The SWM empirical studies in this paper are being put into practice in the ongoing projects concerning search tools at the EPO.
Keywords: Ontologies | Search strategies | Patent search | Prior-art search | BPMN | CMMN
مقاله انگلیسی
3 Thermocapillary-buoyancy convection of a power-law fluid layer heated from below
همرفت حرارتی-شناوری یک لایه سیال قانون-قدرت که از زیر گرم می شود-2020
Buoyant Marangoni convection of a power-law fluid confined in a shallow cavity heated from below is inves- tigated. The free upper surface of the system is assumed to be flat and underformable. A simplified analytical model, valid for an infinite layer, is derived on the basis of the parallel flow approximation. The criteria, for the onset of convection, are predicted for both shear-thinning and shear thickening fluids. For finite amplitude con- vection, the effects of the power law model on the fluid flow, temperature field and heat transfer are discussed. A good agreement is found between the simplified model and the numerical results obtained by solving the full governing equations, provided that the strength of convection is small enough for the flow pattern to remain parallel.
Keywords: Onset of motion | Power-law model | Critical rayleigh and marangoni numbers | nusselt number
مقاله انگلیسی
4 Experimental study of two-phase oil : Polymer flow in horizontal flow path
مطالعه تجربی روغن دو فاز : جریان پلیمر در مسیر جریان افقی-2019
Two-phase flow inside the oil and gas wells and flow path lines is a usual occurrence in petroleum and petrochemical studies. Due to its complexity, flow transfer parameters such as hold up and pressure drop and their dependency on the flow regime maps are not well understood yet. This study is aimed at analyzing holdup for oil- water system and evaluation of this parameter by means of Image processing under different available flow regime conditions. In addition, different oil-polymer systems have been studied to evaluate the impact of polymer concentration on transport criteria. The experimental setup used for this study is consisted of a 12m long Plexiglas pipe with an inner diameter of 30 mm. The results revealed that the only polymer solutions with polymer concentration below than 333 ppm behave as Newtonian fluids. The results showed that low concentration of polymer solution acts as drag reducing agent and reduces the amount of pressure gradient in comparison with oil – water system. Furthermore, the change in flow pattern map between oil-low concentration polymer solution and oil-high concentration polymer solution systems have been analyzed. The results showed that high concentration polymer solution not only leads to higher degrees of pressure drop but also impacts the flow pattern map and more specifically the Three-Layer flow regime cannot be observed in such flow systems. Therefore, a generalized model has been developed to define the flow regime map and the transition criteria between different flow regimes as well as pressure drop and hold up for oil – polymer systems.
Keywords: Non-Newtonian two-phase flow | Flow pattern recognition | Pressure drop | Drag reducing agent | Polymer pressure loss | Holdup
مقاله انگلیسی
5 A new method for voidage correlation of gas-liquid mixture based on differential pressure fluctuation
یک روش جدید برای همبستگی تخلیه مخلوط گاز و مایع بر اساس نوسان فشار دیفرانسیل-2019
Differential pressure of gas-liquid mixture contains abundant information about fluid flow and its nature. In this paper, a differential pressure across a Venturi tube is measured for a gas-liquid mixture. Trend component and fluctuation components of the differential pressure are extracted using Extreme-Point Symmetric Mode Decomposition. The analysis shows that the mean of the trend component is related to liquid flowrate, and the amplitude of the fluctuation components is correlated to voidage and flow pattern. Hence, a fluctuation coefficient based approach to access voidage is proposed. This is based on the trend and fluctuation components. Since there exists an influence of gas/liquid flowrate, fluid density and voidage on fluctuation coefficient, their qualitative relationships are analyzed to find the appropriate variables to modify the fluctuation coefficient. Experimental data are used to determine the appropriate specific modification parameters. The modified fluctuation coefficient is found to be flow pattern dependent, and hence fuzzy pattern recognition is adopted to identify flow patterns combining statistics from differential pressure. Finally, a flow pattern-based correlation is proposed to estimate the voidage. Verifications through confrontation with experimental results show that the proposed correlation is effective in estimating voidage of mixtures
Keywords: Gas-liquid mixture | Differential pressure | Fluctuation | Voidage | Extreme-Point Symmetric Mode | Decomposition | Fuzzy pattern identification
مقاله انگلیسی
6 An improved model for gas-liquid flow pattern prediction based on machine learning
یک مدل بهبود یافته برای پیش بینی الگوی جریان گاز مایع بر اساس یادگیری ماشین-2019
The determination of flow patterns is a fundamental problem in two-phase flow analysis, and an accurate model for gas-liquid flow pattern prediction is critical for any multiphase flow characterization as the model is used in many applications in petroleum engineering. We developed a new model based on machine learning techniques via dimensionally analyzing more than 8000 laboratory multi-phase flow tests. As shown in the test results, the flow pattern is affected by fluid properties, in-situ flow rates of liquid and gas, flow conduit geometry and mechanical properties. Applying hydraulic fundamentals and dimensional analysis, three upscaling numbers are developed to reduce the number of freedom dimensions. These dimensionless variables are easy to use for upscaling and have physical meanings. Machine learning techniques on the dimensionless variables significantly improved their predictive accuracy. Until now the best matching on these laboratory data was approximately 80% using the most recently developed semi-analytical models. The quality of the matching is improved to 90% or greater on the experimental data using machine learning techniques.
Keywords: Machine learning | Data analytics | Two-phase flow model | Predictive analytics | Flow pattern | Gas-liquid modeling
مقاله انگلیسی
7 Robust identification of air traffic flow patterns in Metroplex terminal areas under demand uncertainty
شناسایی دقیق الگوهای جریان ترافیکی هواپیما در مناطق ترمینال Metroplex تحت عدم اطمینان تقاضا-2017
Multi-Airport Systems (MAS), or Metroplexes, serve air traffic demand in cities with two or more airports. Due to the spatial proximity and operational interdependency of the air ports, Metroplex airspaces are characterized by high complexity, and current system struc tures fail to provide satisfactory utilization of the available airspace resources. In order to support system-level design and management towards increased operational efficiency in such systems, an accurate depiction of major demand patterns is a prerequisite. This paper proposes a framework for the robust identification of significant air traffic flow patterns in Metroplex systems, which is aligned with the dynamic route service policy for the effective management of Metroplex operations. We first characterize deterministic demand through a spatio-temporal clustering algorithm that takes into account changes in the traffic flows over the planning horizon. Then, in order to handle uncertainties in the demand, a Distributionally Robust Optimization (DRO) approach is proposed, which takes into account demand variations and prediction errors in a robust way to ensure the reliability of the demand identification. The DRO-based approach is applied on pre-tactical (i.e. one day planning) as well as operational levels (i.e. 2-h rolling horizon). The framework is applied to Time Based Flow Management (TBFM) data from the New York Metroplex. The framework and results are validated by Subject Matter Experts (SMEs).
Keywords: Multi-airport system | Terminal area operation | Air traffic demand | Air traffic management | Distributionally robust optimization
مقاله انگلیسی
8 HyperFlow: A model of computation, programming approach and enactment engine for complex distributed workflows
HyperFlow: یک مدل محاسبه، روش برنامه نویسی و موتور تصویب برای گردش کار توزیع پیچیده-2016
Article history:Received 30 March 2015 Received in revised form 13 August 2015Accepted 28 August 2015Available online 26 September 2015Keywords:Scientific workflows Process networks Workflow programming Workflow patterns Workflow enactmentThis paper presents HyperFlow: a model of computation, programming approach and enactment engine for scientific workflows. Workflow programming in HyperFlow combines a simple declarative description of the workflow structure with low-level implementation of workflow activities in a mainstream scripting language. The aim of this approach is to increase the programming productivity of workflow developers who are skilled programmers and desire a programming experience similar to the one offered by a mature programming ecosystem. Combining a declarative description with low-level programming enables elimination of shim nodes from the workflow graph, considerably simplifying workflow implementations. The workflow description is based on a formal model of computation (Process Networks) and is characterized by a simple and concise syntax, utilizing just three key abstractions—processes, signals and functions. Yet it is sufficient for expressing complex workflow patterns in a simple way. The adopted model of computation implemented in the HyperFlow workflow engine enables fully distributed and decentralized workflow enactment. The paper describes HyperFlow from the perspective of its workflow programming capabilities, the adopted model of computation, as well as the enactment engine, in particular its distributed workflow enactment capability. The provenance model and logging features are also presented. Several workflow examples derived from other workflow systems and reimplemented in HyperFlow are extensively discussed.© 2015 Elsevier B.V. All rights reserved.1.
Scientific workflows | Process networks | Workflow programming | Workflow patterns | Workflow enactment
مقاله انگلیسی
9 اعطای پاداش بازار به الگوهای افزایش درآمد: اهمیت الگوهای جریان های وجوه نقد، دستکاری اقلام تعهدی و دستکاری فعالیت های واقعی
سال انتشار: 2015 - تعداد صفحات فایل pdf انگلیسی: 38 - تعداد صفحات فایل doc فارسی: 45
مطالعه حاضر بررسی می کند ایا شرکت ها در ارتباط با روش های انها در دستیابی به الگوی متوالی افزایش درامدهای مثبت، دارای مضارب متفاوتی از قیمت-درامدها، می باشند؟ نتایج اصلی تحقیق حاضر نشان می دهد زمانی که الگوی افزایش درامدها توسط الگوی مشابه جریان های وجوه نقد، پشتیبانی می شود، سهامداران بازار، مضارب بالاتر قیمت-درامدها را به شرکت ها اختصاص می دهند. همچنین سهامداران بازار، ضرایب پایین تر قیمت-درامدها را شرکت های مظنون به استفاده از مدیریت درامدهای مبتنی بر موارد تعهدی، دستکاری فروش، و تولید اضافی، برای رسیدن به الگوی درامدها، تعیین می کنند. هرچند، نتایج حاصل نشان می دهد که سهامداران بازار، شرکت هایی را که مظنون به داشتن الگوی درامدها با استفاده از کاهش فرصت طلبانه هزینه های اختیاری هستند، بازخواست نمی کنند.
واژه های کلیدی: الگوهای درامد | از دست دادن الگوی مقایسه ای | مدیریت درامدها | دستکاری فعالیت های واقعی
مقاله ترجمه شده
10 اثر زبری سطح بر ضریب دبی و کاویتاسیون های سرریزهای اوجی با بهره گیری از مدل‌های فیزیکی
سال انتشار: 2014 - تعداد صفحات فایل pdf انگلیسی: 7 - تعداد صفحات فایل doc فارسی: 15
پیش زمینه: سازه سرریز جریان از مسائل مهم در احداث سد به شمار می‌آید و نوع طرح سرریز با توجه به ضریب دبی مناسب و بررسی بلندمدت عملکرد هیدرولیکی طرح سرریز بسیار حائز اهمیت است.
هدف: انتخاب و تأمین گراف‌های مناسب براساس نوع زبری دیواره در بخش‌های مختلف سرریزهای اوجی کلیدی برای استفاده از این سرریزها در پروژه‌های احداث سد است. جهت انجام این کار، با بهره گیری از مدل فیزیکی – هیدرولیکی، مجتمع عالی آب خوزستان و وزارت نیرو آزمایش‌های اندازه گیری را انجام دادند و پارامترهای هیدرولیکی را مورد مشاهده قرار داده و ضریب دبی را در میدان‌های مختلف ازجمله زبری سطح در مدل سرریز اوجی را تحلیل کردند.
نتایج: آزمایش‌های انجام شده روی مدل با 6 نوع زبری سطحی و 5 سرعت جریان متفاوت بطور کل شامل 30 آزمایش بودند.
نتیجه گیری: در پایان، افزایش زبری نسبی ضریب دبی سرریز بطور مناسبی با زبری سطح کاهش می‌یابد. هم چنین نتایج آزمایش‌ها در دبی‌های متفاوت نشان می‌دهند که افزایش زبری سبب کاهش شاخص کاویتاسیون می‌شود.
کلیدواژه‌ها: الگوی جریان | ضریب دبی | سرریز اوجی | مدل فیزیکی | زبری
مقاله ترجمه شده
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