Academic literature on the topic 'Sliding reserve'
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Journal articles on the topic "Sliding reserve"
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Jia, Chao, Feng Gao, and Yong Li. "Progressive Failure Research on Foundation Surface of Concrete Gravity Dam." Advanced Materials Research 163-167 (December 2010): 1038–43. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1038.
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Concrete dam safety is one of the hot issues in dam study with the increasing of dam’s scale and height. Sliding failure along foundation surface is a potential failure mode of concrete gravity dam, and this mode is relatively rare in practical engineering. Strength reduction method is used to analyze the progressive failure along foundation surface of concrete gravity dam, and the strength parameters of weak layer in the foundation surface are reduced to analyze the occurrence and development regularity of plastic zone. If the plastic zone of foundation surface is totally coalescent, the dam will slide along the foundation surface. To track this process, the failure path and the safety reserve coefficient would be determined. This result will provide certain scientific basis for anti-sliding stability analysis of concrete gravity dam.
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Merheb, Abdel-Razzak, Hassan Noura, and François Bateman. "Design of passive fault-tolerant controllers of a quadrotor based on sliding mode theory." International Journal of Applied Mathematics and Computer Science 25, no. 3 (September 1, 2015): 561–76. http://dx.doi.org/10.1515/amcs-2015-0042.
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Abstract In this paper, sliding mode control is used to develop two passive fault tolerant controllers for an AscTec Pelican UAV quadrotor. In the first approach, a regular sliding mode controller (SMC) augmented with an integrator uses the robustness property of variable structure control to tolerate partial actuator faults. The second approach is a cascaded sliding mode controller with an inner and outer SMC loops. In this configuration, faults are tolerated in the fast inner loop controlling the velocity system. Tuning the controllers to find the optimal values of the sliding mode controller gains is made using the ecological systems algorithm (ESA), a biologically inspired stochastic search algorithm based on the natural equilibrium of animal species. The controllers are tested using SIMULINK in the presence of two different types of actuator faults, partial loss of motor power affecting all the motors at once, and partial loss of motor speed. Results of the quadrotor following a continuous path demonstrated the effectiveness of the controllers, which are able to tolerate a significant number of actuator faults despite the lack of hardware redundancy in the quadrotor system. Tuning the controller using a faulty system improves further its ability to afford more severe faults. Simulation results show that passive schemes reserve their important role in fault tolerant control and are complementary to active techniques
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Alt, B., J. P. Blath, F. Svaricek, and M. Schultalbers. "Multiple Sliding Surface Control of Idle Engine Speed and Torque Reserve With Dead Start Assist Control." IEEE Transactions on Industrial Electronics 56, no. 9 (September 2009): 3580–92. http://dx.doi.org/10.1109/tie.2009.2021593.
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Shi, X., and R. Richards. "Seismic bearing capacity with variable shear transfer." Bulletin of the New Zealand Society for Earthquake Engineering 28, no. 2 (June 30, 1995): 153–63. http://dx.doi.org/10.5459/bnzsee.28.2.153-163.
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The seismic degradation of bearing capacity for drained soils is shown to depend primarily on two factors related to earthquake acceleration: (a) the lateral inertial forces in the structure transmitted as shear at the foundation-soil interface and (b) the lateral body forces in the soil itself. Both induce shear stresses using up the reserve strength of the soil to carry the footing load. During those short periods when this reserve strength provided by the static design factor of safety is exhausted, the footing settles and moves laterally. Solutions for this seismic limit state defining the critical acceleration at which it occurs are determined for any value of shear transfer first by the "exact" method of characteristics and then by a simple Coulomb-type approximate mechanism. Expressions for seismic bearing capacity factors that are directly related to their static counterparts are nearly identical by either method. Thus a straightforward sliding block procedure based on the Coulomb mechanism with examples is presented for computing accumulating settlements due to the periodic loss of bearing capacity. Conversely, this approach leads to a modified static design procedure for shallow footings to limit seismic settlements in a prescribed earthquake intensity zone.
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Liang, Yan, Chao Liu, Tong Lu Li, and Ping Li. "The Effect of the Filling Caves on Loess Slope Stability in Irrigation." Advanced Materials Research 753-755 (August 2013): 648–52. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.648.
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Landslides are serious geological disasters in loess areas. In order to study the effect of the filling caves in the edge of loess tableland on loess slope stability, the slope stability of sliding from the caves was calculated in irrigation when caves were filled with compacted soil, lime soil, lime-ash soil and non-filled. The results show when caves are filled with lime soil the slope stability is the highest. The effects of variability of the physical and mechanical property indexes of caver filler on loess slope stability were researched further. The results show that (1) the variation coefficients of unit weigh and the shear strength indexes of cave filler lime soil have small effect on the average value of safety reserve, but have big effect on the standard deviation of safety reserve, which explains that the design risks increase while the variation coefficient increasing. (2) with the increase of variation coefficients of unit weigh and the shear strength indexes of cave filler the failure probability increases. Especially when variation coefficient is bigger than 0.3, the failure probability of loess slope is very sensitive to variation coefficient. (3) the effect of correlation coefficient among unit weight and the shear strength indexes of cave filler on failure probability increases with the variation coefficient increasing. It is very important to guarantee filling project. Good quality of filling construction will decrease the variability of cave filler, heighten the stability of loess slope, and decrease the occurrence of loess disasters.
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Li, Bo, Zhijun Zhang, Yan Liu, and Shengmei Yang. "Evaluation Standard for Safety Coefficient of Roller Compacted Concrete Dam Based on Finite Element Method." Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/601418.
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The lack of evaluation standard for safety coefficient based on finite element method (FEM) limits the wide application of FEM in roller compacted concrete dam (RCCD). In this paper, the strength reserve factor (SRF) method is adopted to simulate gradual failure and possible unstable modes of RCCD system. The entropy theory and catastrophe theory are used to obtain the ultimate bearing resistance and failure criterion of the RCCD. The most dangerous sliding plane for RCCD failure is found using the Latin hypercube sampling (LHS) and auxiliary analysis of partial least squares regression (PLSR). Finally a method for determining the evaluation standard of RCCD safety coefficient based on FEM is put forward using least squares support vector machines (LSSVM) and particle swarm optimization (PSO). The proposed method is applied to safety coefficient analysis of the Longtan RCCD in China. The calculation shows that RCCD failure is closely related to RCCD interface strength, and the Longtan RCCD is safe in the design condition. Considering RCCD failure characteristic and combining the advantages of several excellent algorithms, the proposed method determines the evaluation standard for safety coefficient of RCCD based on FEM for the first time and can be popularized to any RCCD.
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Calista, Monia, Francesco Mascioli, Valeria Menna, Enrico Miccadei, and Tommaso Piacentini. "Recent Geomorphological Evolution and 3D Numerical Modelling of Soft Clastic Rock Cliffs in the Mid-Western Adriatic Sea (Abruzzo, Italy)." Geosciences 9, no. 7 (July 12, 2019): 309. http://dx.doi.org/10.3390/geosciences9070309.
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Geomorphological evolution, erosion and retreat processes that affect the rocky coasts of the mid-western Adriatic Sea (Abruzzo, Central Italy) are the subject of this research. This coastal sector, one of the few examples of clastic soft rock coasts in the Mediterranean Sea, is characterized by active, inactive and paleo cliffs, as well as coastal slopes, composed of the clayey-sandy-arenaceous-conglomeratic marine sequence (Early-Middle Pleistocene) covered by continental deposits (Late Pleistocene-Holocene). This study provides geomorphological and 3D modelling stability analyses of the cliffs of Torre Mucchia, Punta Lunga, Punta Ferruccio (Ortona, CH) and Punta Aderci (Vasto, CH), which are popular tourist sites included in natural reserve areas. They are representative of two main types of active cliffs on soft clastic rocks: cliffs on sandstone and cliffs on conglomerate with notches. In order to evaluate the processes and factors that induce cliffs to retreat and their recent evolution, the research was based on a DEM analysis (LIDAR 2 × 2 m data), aerial photos and an orthoimages interpretation, detailed geological–geomorphological surveys, and a structural analysis; field and remote investigations were combined with numerical modelling with a FLAC3D calculation code. Geological and geomorphological field data provided reliable 3D models, and FLAC3D numerical analyses allowed the definition of the most critical and/or failure areas, and the evaluation of the controlling factors, evolution mechanisms of the slopes and the sliding kinematics of gravitational instability phenomena. Different retreat mechanisms have been observed all along the investigated coastal sectors, induced by gravitational processes due to coastal erosion cycles at the foot of the cliffs, and controlled by lithological features and joints systems. The geomorphological analysis combined with the 3D modelling (i) showed that the retreat process of the cliffs is connected to translational slides and rockfalls (cliffs on sandstone), combined rockfalls, and topples (cliffs on conglomerate), largely controlled by main joints; (ii) defined the most critical areas along the cliffs. These results are of great interest in the assessment of hazard connected to potential sliding on the cliffs. Their implementation within Geographical Information Systems provides a valuable contribution to the integrated management of coastal areas, strongly improving the identification and prediction of landscape changes and supporting a new geomorphological hazards assessment, in areas of high tourism, as well as natural and cultural landscape value.
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Han, Lu, Chongchong Yu, Cuiling Liu, Yong Qin, and Shijie Cui. "Fault Diagnosis of Rolling Bearings in Rail Train Based on Exponential Smoothing Predictive Segmentation and Improved Ensemble Learning Algorithm." Applied Sciences 9, no. 15 (August 2, 2019): 3143. http://dx.doi.org/10.3390/app9153143.
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The rolling bearing is a key component of the bogie of the rail train. The working environment is complex, and it is easy to cause cracks and other faults. Effective rolling bearing fault diagnosis can provide an important guarantee for the safe operation of the track while improving the resource utilization of the rolling bearing and greatly reducing the cost of operation. Aiming at the problem that the characteristics of the vibration data of the rolling bearing components of the railway train and the vibration mechanism model are difficult to establish, a method for long-term faults diagnosis of the rolling bearing of rail trains based on Exponential Smoothing Predictive Segmentation and Improved Ensemble Learning Algorithm is proposed. Firstly, the sliding time window segmentation algorithm of exponential smoothing is used to segment the rolling bearing vibration data, and then the segmentation points are used to construct the localized features of the data. Finally, an Improved AdaBoost Algorithm (IAA) is proposed to enhance the anti-noise ability. IAA, Back Propagation (BP) neural network, Support Vector Machine (SVM), and AdaBoost are used to classify the same dataset, and the evaluation indexes show that the IAA has the best classification effect. The article selects the raw data of the bearing experiment platform provided by the State Key Laboratory of Rail Traffic Control and Safety of Beijing Jiaotong University and the standard dataset of the American Case Western Reserve University for the experiment. Theoretical analysis and experimental results show the effectiveness and practicability of the proposed method.
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Wang, Junyuan, Jingtai Wang, Wenhua Du, Jiping Zhang, Zhijian Wang, Guanjun Wang, and Tao Li. "Application of a New Enhanced Deconvolution Method in Gearbox Fault Diagnosis." Applied Sciences 9, no. 24 (December 5, 2019): 5313. http://dx.doi.org/10.3390/app9245313.
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When the mechanical transmission mechanism fails, such as gears and bearings in the gearbox, its vibration signal often appears as a periodic impact. Considering the influence of noise, however, the fault signal is often submerged in the noise, so it is necessary to propose a feasible and effective fault extraction method. MOMEDA (multipoint optimal minimum entropy deconvolution adjusted) overcomes the tedious iterative process of MED (minimum entropy deconvolution) and overcomes the resampling trouble in MCKD (maximum correlated kurtosis deconvolution). It is suitable for dealing with periodic impact signal. Besides, aiming at the poor ability of MOMEDA to capture the deconvolution result of target function in a strong noise environment, this paper proposes an improved MOMEDA gearbox fault feature extraction method. Considering that MOMEDA has poor anti-noise performance and can easily cause misdiagnosis in a strong noisy environment, this paper constructs an autoregressive mean sliding model to improve the noise immunity of MOMEDA. Firstly, the stability of the test signal is judged by the autocorrelation coefficient (ACF) and the partial correlation coefficient (PACF). Secondly, the ARMA (autoregressive moving average) model is constructed and a set of optimal model coefficients are obtained to filter the signal, which greatly improves MOMEDA’s ability to capture fault features. Thirdly, the fault feature is extracted by MOMEDA, and the fault information is extracted accurately under a strong noise environment. Finally, compared with AR-MED, ARMAMED, and other methods, the advantages of ARMAMOMEDA are verified. Moreover, the effectiveness and superiority of the proposed method are verified by simulation signals and experimental data from the Case Western Reserve University Bearing Data Center.
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Dezhin, Dmitry, and Roman Ilyasov. "Development of fully superconducting 5 MW aviation generator with liquid hydrogen cooling." EUREKA: Physics and Engineering, no. 1 (January 10, 2022): 62–73. http://dx.doi.org/10.21303/2461-4262.2022.001771.
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The use of liquid hydrogen as a fuel will be inevitable in the aviation of the future. This statement means that manufacturers will also implement liquid hydrogen for cooling all superconducting aviation equipment of an electric propulsion system. The development of fully electric aircraft is the most promising solution in this case. Scientists from the Department of electrical machines and power electronics of Moscow aviation institute have conducted calculations and theoretical researches of critical specific mass-dimensional parameters (MW/ton and MW/m3 at 21 K) of fully superconducting aviation synchronous generator of the electric propulsion system. The results are in this article.
The article discusses the results 3D finite element modeling (FEM) simulation of a 5 MW fully superconducting synchronous generator with combined excitation. Superconducting armature and axial excitation windings based on second generation high temperature superconductors (HTS-2G) are located on the stator, which makes it possible to contactlessness and the absence of sliding seals. A dry gap will reduce gas-dynamic losses and increase the nominal peripheral speed of the rotor. The use of liquid hydrogen as a coolant makes it possible to significantly increase the linear load of the generator, and high current densities to reduce the cross-sectional area of the coils, which will make it possible to place them in individual cryostats in the future. Individual cryostats will allow to remove the heat release of magnetic losses from the cryogenic zone and reduce the consumption of refrigerant. For the purpose of internal redundancy of the HTS coils, the machine has a complete set of reserve winding made of ultrapure aluminum, also cooled by liquid hydrogen. If the superconducting coils get out of the stand, the generator will provide 15 % power on standby
Dissertations / Theses on the topic "Sliding reserve"
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Wästlund, Dag. "Progressive failure research on foundation surface of the Longtan gravity dam." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-161213.
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The most common failure of concrete gravity dams is sliding along the foundation surface. This thesis studies progressive failure of the Longtan dam on the upper Hongshuie river in china.Two methods are used in this thesis; the Safety Reserve Factor (SRF) method and the Overload method. The SRF-method is used as a tool to study sliding failure along the foundation weak layer of the Longtan dam. Strength reduction coefficients decrease the cohesion and friction angle values for the weak layer of the foundation. Simulations with reduced shear strength parameter values gives information about the development of the plastic zone. The ultimate bearing resistance and the failure path along the foundation are obtained. The safety reserve coefficient is established through the strength reduction coefficients, when the plastic zone of the foundation is totally coalescent. To analyse the development of the plastic zone along the dam foundation with the strength reserve method, the commercial finite element software MSC.Marc is used. The results of the Safety Reserve Factor method (SRF) show that the failure of the dam is highly related to the strength of the interface between the dam and rock foundation. The strength reserve factor is determined to 2.4. The Overload method gives a visual deformation shape of the dam structure and pressure load at the moment of failure.Dammar har används i mer än 5000 år (Yang et al. 1999) och är fortfarande en viktig källa för energiutvinning. Det största antalet dammar finns i Kina och man tror att det finns över 80,000 dammar i landet (Shapiro 2001). En ökning av dammars kapacitet och antal sker, vilket resulterat i ett behov av bättre sätt för att utvärdera säkerhetsparametrar som betongkvalité, styvhet och homogenitet av bergmassa. Simuleringar av dammkonstruktioner kan ge värdefull information om dessa parametrar och kan därigenom bidra till att förbättra en damms stabilitet och sänka konstruktionskostnader. I det här examensarbetet utvärderas och modelleras Longtan dammen i övre Hongshui floden i Kina. Den vanligaste orsaken till haveri av betongdammar är glidning mellan betonglager och bergmassan. I den här rapporten simuleras ett svagare lager mellan betong och bergmassa och utvecklingen av kontaktbrottsvägen visualiseras och utvärderas med progressiva haveri metoden. Det svagare lagrets hållfasthetskoefficienter; friktionsvinkel och kohesion, reduceras för att analysera utbredningen av den plastiska zonen. Resultaten visar att en överskridning av draghållfastheten för betong börjar vid dammens häl och att kompressionsbristningsgränsen överskrids vid dammens tå när hållfasthetskoefficienterna reduceras. Säkerhetsreservskoefficienten för Longtan dammen erhålls då gränsytan mellan betong och berg är helt plastisk. För att analysera utbredningen av den plastiska zonen längs med dammfundamentet med progressiva haveri metoden används den kommersiella finita element mjukvaran MSC.Marc. Resultaten från säkerhetskoefficientfaktormetoden visar att ett haveri av gravitations dammar är i hög grad relaterad till hållfastheten mellan betongen och bergets gränsyta. Säkerhetskoefficientfaktorn bestäms till 2.4. För att bestämma Longtan dammens maximala vattenbelastningskapacitet används Överbelastningsmetoden. Det maximala vattentryck som Longtan dammen klarar av utan att haverera simuleras med hjälp av en vätska vars densitet ökas mellan modellkörningar. Dammens förskjutning når till sist en punkt där den ökar kraftigt och dammens mutationsdeformationstillstånd har uppnåtts. En visuell deformationsbeskrivning av dammen ges genom modellkörningar och överbelastningsfaktorn bestäms.
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Морозов, Костянтин В’ячеславович. "Методи і засоби побудови моделей поведінки небазових відмовостійких багатопроцесорних систем." Doctoral thesis, Київ, 2021. https://ela.kpi.ua/handle/123456789/40485.
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Дисертація присвячена проблемі побудови графо-логічних моделей
(GL-моделей) небазових відмовостійких багатопроцесорних систем (ВБС) з
метою розрахунку їх параметрів надійності шляхом проведення статистичних
експериментів із вищезгаданими моделями.
Запропоновано метод перетворення GL-моделей за рахунок модифікації
виразу будь-якої реберної функції так званої МВР-моделі. Метод базуються на
зміні як однієї, так і обох частин виразу реберної функції та дозволяє
модифікувати модель так, що на деяких векторах стану системи вона, на відміну
від оригінальної, починає показувати роботозданий і/або нероботоздатний стан.
Проаналізовано межі впливу для загального випадку модифікації як однієї, так і
кількох реберних функцій на зміну поведінки моделі.
Вперше запропоновано аналітичний апарат, що дозволяє визначати вектор
стану t-діагностованої ВБС на основі результатів взаємного тестування
процесорів, згідно із моделлю Препарати-Метца-Чена (ПМЧ-модель), для
довільної топології зв’язків між ними.
Вперше запропоновано метод побудови GL-моделей так званих зважених
систем, в яких кожний компонент має деяку вагу, що характеризує його вклад в
роботоздатність системи в цілому, а також узагальнення методу побудови
GL-моделей, що базується на використанні в якості реберних функцій
багатозначної логіки та дозволяє використовувати їх для побудови моделей
систем, для яких, як і їх компонентів характерні більше двох станів
роботоздатності.
Запропоновано метод побудови GL-моделей ієрархічних систем шляхом
композиції декількох МВР-моделей, а також моделей систем, що складаються з
кількох підсистем та мають ковзний резерв.
Book chapters on the topic "Sliding reserve"
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Hou, Xiaoqiang, Jierui Liu, Xinfei Wang, Zhongren Zhou, and Honglu Jia. "Research on Improvement Calculation Method of Design Thrust of Anti Slide Pile." In Lecture Notes in Civil Engineering, 180–94. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1260-3_17.
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AbstractAt present, based on the transfer coefficient method, most of the anti-slide pile design thrusts are calculated by the overload method and the strength reserve method respectively. Many algorithms only consider the remaining sliding force behind the pile and the safety factor that meets the requirements of the design conditions. Generally, the safety factor is the safety factor of the sliding slope behind the pile after the anti slide pile is reinforced. For the entire landslide, there are two safety factors before and after the pile, which is not the design safety factor target value, and there is a big difference between the safety factor and the treatment goal required by the specification. Through the study of the pile-soil interaction of anti-slide piles, it is believed that in addition to the active residual sliding force transmitted by the blocks behind the pile, the anti-slide piles are simultaneously subjected to the passive residual anti-sliding force transmitted upwards by the blocks in front of the pile. The stress analysis shows that: Firstly, according to the different active and passive properties of anti-sliding force transmission and sliding force transmission, the mechanical model of anti-sliding force transmission is studied, and the calculation formula of anti-sliding force transmission coefficient is derived; Secondly, It is believed that the anti-slide pile provides horizontal thrust to the landslide, and two components of the sliding surface direction and the vertical sliding surface direction are generated. The balance equation is established and the overload method and the strength reserve method of anti-slide pile thrust calculation formula are derived; Thirdly, according to the principle of setting piles in the anti-slip section, the optimal location of anti-slide piles are proposed; Fourthly, after verification of cases, the safety factors before and after the piles calculated by the overload method are basically equal, and consistent with the design safety factors. Calculation result shows that the strength reserve method to calculate the safety factor before the pile is accurate and reliable, and the result of the safety factor behind the pile is relatively small.
Conference papers on the topic "Sliding reserve"
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Alt, Benedikt, Jan Peter Blath, Ferdinand Svaricek, and Matthias Schultalbers. "Control of idle engine speed and torque reserve with higher order sliding modes." In 2009 IEEE International Conference on Control Applications (CCA). IEEE, 2009. http://dx.doi.org/10.1109/cca.2009.5280884.
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Alt, Benedikt, Ferdinand Svaricek, Jan Peter Blath, and Matthias Schultalbers. "Multiple sliding surface control of idle engine speed and torque reserve with load torque estimation." In 2008 International Workshop on Variable Structure Systems (VSS 2008). IEEE, 2008. http://dx.doi.org/10.1109/vss.2008.4570681.
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Alt, Benedikt, Jan Peter Blath, Klaus-Dieter Otto, Ferdinand Svaricek, and Matthias Schultalbers. "Observer-based output tracking of engine speed and torque reserve at idle with sliding mode control." In European Control Conference 2007 (ECC). IEEE, 2007. http://dx.doi.org/10.23919/ecc.2007.7068736.
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Abidiy, Izzad, Yolani Bawono, R. Aulia Muhammad Rizky, Rico Pradityo, Ramadhani Rachman, Hanif Thalib, Muhammad Nadrul Jamal, Rahadyan Kusuma, Muhammad Sobirin, and Fata Yunus. "Non Selective Shallow Unconsolidated Well Re-Entry: Case Study in Mahakam Delta." In SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205641-ms.
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Abstract Declining of shallow reservoir reserve urges efficiency effort to switching well architecture from zone-selective gravel pack completion to non-selective tubingless completion. However, zone management in tubingless completion is not as simple as sliding sleeve manipulation in gravel pack well. It requires proper zone isolation of closed zone such as setting plug, tubing patch, or squeezed cement. Therefore, optimum zone management need to be identified to be consistent with cost efficiency effort. Study in determining optimum zone management captured two nearly identic case of 3 zones of selective well and non-selective well. The well cost, production, and its net present value was compared to evaluate how the reservoir production is managed. Although selective well has higher initial well cost, but operation cost during the production is significantly low. On the other hand, even non-selective well has lower initial well cost, due to complication on zone management, non-selective well has higher operation cost. The total cost of problematic non-selective well could nearly reach the selective well cost. The complication is identified as downward movement, i.e. re-accessing previously isolated lower zone and isolating upper zone at once. However, this study suggests that strictly following bottom-up production strategy could potentially avoid the complication by 23% more efficient in production and cost index. Well cost efficiency is not only determined by lower initial well cost. All operating cost during production must be also considered. Optimum well management for both type of completion is a key parameter in order to control the cost efficiency effort. Therefore, well completion design selection must consider not only the cost and production, but also the operation excellence and capability during managing well production in its lifetime.
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Wechsung, Michael, Andreas Feldmüller, and Heiko Lemmen. "Steam Turbines for Flexible Load Operation in the Future Market of Power Generation." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69312.
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In a liberated electricity market with a steadily growing percentage of fluctuating renewables the load related requirements of modern steam power plants are noticeably changing. Whereas the past has seen mainly coal-fired units being operated in base load now highly efficient part load behavior becomes more and more important as well as quickly responding frequency support at minimized investment costs. …In the article various approaches will be identified, discussed and evaluated under economical criteria focused on the above described challenges for future power generating technologies. One central idea is to shift the pure sliding pressure mode down to an intermediate load range where the upper limit is reached at around 70% and optimize the blade path efficiency according to this point. Along with this strategy concepts are presented which allow frequency support from primary to hour- reserve of maximized load steps. Moreover it shall be explained how it is principally possible to use the same cycle conditions for load steps and increasing part load efficiency at the same time. Another idea is to improve the plant performance at lower load ranges by raising the main and reheat steam temperature accompanied by special maintenance concepts. The ideas presented in this article are mainly derived from a steam turbine point of view. Nevertheless some requirements and effects on the overall plant are taken into account additionally. The presented approaches can be applied for new apparatus as for the upgrade of existing units. As the drivers for a more flexible operation of steam plants are especially strong in markets which do not guarantee an attractive utilization of the plant in produced MWhrs/year, investment decisions for new plants have been delayed or cancelled due to the difficult market conditions. Therefore special attention will be paid in this paper to the application of the new flexibility features in power plants which are already in operating and which have been designed originally with the main focus on highest efficiencies in base load operation. The difficulties and limitations given with the existing plant design will most likely be compensated by the economical advantages of the more flexible plant operation after the modernization.
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Hanjawanich, Siriwat, Taylor Shelby, Kanin Laonakornthum, Euan Murdoch, Kanokkorn Piemchaw, Tawatchai Tawatchai Duangkaewwutthikrai, and Wantanee Teerasukakul. "Unlock Mono-Trip Gas Lift Completions Limits by using a New Cement-Through Packer and a Sliding Sleeve with Radio Frequency Identification Capability." In IADC/SPE Asia Pacific Drilling Technology Conference. SPE, 2021. http://dx.doi.org/10.2118/201042-ms.
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Abstract Gas lift is one of the most appropriate artificial lift methods for Gulf of Thailand (GOT) oil operations. As first described in Chapman, W. R. (2005), Mono-trip gas lift (MTGL) completions have continuously improved since their implementation in the early 2000s, increasing recovery by over 15%. MTGL completions enable marginal or sub-economic new wellhead platforms (WHPs) or infill projects to become economical. To overcome the more challenging wellbore environment in which the current technology is unable to be utilized, alternative technology was trialed in 2019 to enhance the MTGL completion without sacrificing the wellbore designs or reserves.
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Zhu, Dawei, Mingyue Cui, Yandong Chen, Yongli Wang, Yunhong Ding, Chunming Xiong, Chong Liang, et al. "First Successful Application of Multi-Stage Proppant Fracturing on Horizontal Well in Carbonate Reservoirs in Iraq." In SPE International Hydraulic Fracturing Technology Conference & Exhibition. SPE, 2022. http://dx.doi.org/10.2118/205281-ms.
Full textAbstract:
Abstract The carbonate reservoir S is a giant limestone reservoir in H Oilfield, Iraq. Although the reserves account for 25%, the production contribution is only 0.4% to the total oilfield production due to poor petrophysical properties. Accordingly, the first proppant fracturing on vertical well was successfully executed in December 2016, which has already achieved a steady production period over than 3 years. In order to further improve the productivity, the first multi-stage proppant fracturing(MSPF) on horizontal well(SH01X) was successfully applied in November 2019, a technique which is rarely reported for porous limestone reservoir in the Middle East. Proppant fracturing in carbonate reservoirs is a technique difficulty worldwide, especially this is a lack of experiences in the Middle East. To ensure the success of this campaign, a holistic technical study including geology evaluation, reservoir performance analysis, drilling trajectory design, completion and fracturing technique design have been carried out based on principle of "geology-engineering integration". This paper will present a comprehensive illustration including treatment design (main completion-fracturing technique, total scale, fracturing fluid, proppant), job execution (mini-frac, main-frac) and post-frac production performance for this successful campaign. True vertical depth (TVD) of Well SH01X is 2720 m and the horizontal section length is 811 m. Based on the main technique of multi-stage proppant fracturing with open hole packers and sliding sleeves, totally 3784.3 m3 fracturing fluid and 452 m3 proppant were pumped in 8 stages. The test production was 3214 BOPD (choke size: 40/64", wellhead pressure: 970 psi). A historical breakthrough in the productivity of S reservoir has been achieved by the campaign. The post-frac evaluation shows that the treatment parameters are consistent with the design. The connectivity between artificial fractures and formation is greatly improved, and the stimulation effect is significant. Currently the "production under controlled pressure" mode has been executed and the stable production under stimulation target rate has been maintained. The systematic "geology-engineering integration" workflow is of significance to the success of the treatment as well as the stimulation effect. MSPF is planned to be a game-changing technique to develop the huge reserves of S reservoir. The experience gained from this case could provide theoretical as well as practical references for similar reservoirs in the Middle East.