Literatura académica sobre el tema "Technically controlled unit"
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Artículos de revistas sobre el tema "Technically controlled unit"
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Kim, Raymond E., Lance T. Uradomo, Grace E. Kim, John D. Morris, Eric M. Goldberg y Peter E. Darwin. "The Effect of Fluoroscopy Control on Cannulation Rate and Fluoroscopy Time in Endoscopic Retrograde Cholangiopancreatography Training". Korean Journal of Pancreas and Biliary Tract 26, n.º 1 (31 de enero de 2021): 43–48. http://dx.doi.org/10.15279/kpba.2021.26.1.43.
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Background/Aim: Endoscopic retrograde cholangiopancreatography (ERCP) training requires varying degrees of staff assistance regarding operation of the fluoroscopy machine via a foot pedal. Efficiency is important to acquire during this training due to radiation risks. In this study, we evaluate the effect of controlling endoscopy and fluoroscopy unit on duct cannulation rates (CRs) and total fluoroscopy time (FT) for fellows in training.Methods: 204 patients undergoing ERCP were randomized to one of two groups: 1) “Endoscopist Driven” group in which the endoscopist controlled the foot pedal for fluoroscopy, and 2) “Assistant Driven” group in which attending or fellow controlled the foot pedal while the other team member controlled the endoscope. Various measures including selective duct CR and total FT were recorded.Results: There was no significant difference in mean procedure duration between the two groups (32 minutes vs. 33 minutes, <i>p</i>=0.70). There was also no statistically significant difference in CR (83.7% vs. 77.4%, <i>p</i>=0.25) or FT (3.27 minutes vs. 3.54 minutes, <i>p</i>=0.48).Conclusions: ERCP is a technically challenging procedure which requires extensive supervision. This study demonstrates that CR and FT are not affected by who controls the fluoroscopy.
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Srivastava, Manish, Prakhar Singh, Sandeep Verma y Prince Singh. "Power Flow Control in Transmission Line by Using UPFC". International Journal of Research in Engineering, Science and Management 4, n.º 4 (28 de abril de 2021): 126–29. http://dx.doi.org/10.47607/ijresm.2021.670.
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The power transfer capacity of electrical transmission lines is typically constrained by the capacity of large signals. Economic considerations such as the high cost of long lines and the income from the supply of additional power make it possible to pursue both economically and technically viable ways to increase the stability cap intensively. On the other hand, the production of efficient ways to use the full thermal capacity of transmission systems. The power industry has already begun to be affected by fast development in the field of power electronics. This is one direct consequence of the idea of aspects of FACTS, which has become possible due to the progress realized in power electronic devices. In theory, the FACTS devices can provide rapid control of real and Var power through transmission line. The UPFC is a FACTS family member with very appealing characteristics. Many parameters can be independently controlled by this unit. An alternative means of minimizing transmission system oscillations is given by this unit. The choice of input signals and the adopted control strategy for this system in order to dampen power oscillations in an efficient and robust manner are an important issue. In order to achieve the maximum desire effect in solving the first swing stability problem, the UPFC parameters can be regulated. In bulky power transmission systems with long transmission lines, this problem arises. A MATLAB Simulink Model with UPFC to test the efficiency of the electrical transmission system is considered in this paper. The main purpose of this analysis paper is to research different studies performed in the past to minimize UPFC transmission line losses.
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Anwar, Muhammad Naveed, Muhammad Khizar Hayat, Zunnoor Ahmad, Mawara Iftikhar y Mohammad Ahmed Arsalan Khan. "Endoscopic Retrograde Cholangiopancreatography (ERCP) profile of a tertiary care hospital in Peshawar: indications, procedures, and complications". Journal of Rehman Medical Institute 6, n.º 2 (10 de julio de 2020): 17–20. http://dx.doi.org/10.52442/jrmi.v6i2.177.
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Introduction: Endoscopic Retrograde Cholangio-pancreatography (ERCP), being a useful though technically demanding diagnostic and therapeutic procedure to evaluate and treat diseases of biliary and pancreatic ducts is dependent in large part for its success on the skill of the operator.
Objective: To determine the indications, procedures performed and success rate of ERCP at a tertiary care center of Peshawar.
Materials & Methods: A descriptive cross-sectional study was carried out at the Endoscopy Unit of Rehman Medical Institute (RMI) from January 2020 to April 2020 using universal sampling technique. All ERCP procedures done in the endoscopy unit from January 2019 to December 2019 were included in the study regardless of their age, gender, ethnicity or presenting complains. Any ERCP that did not have complete data were excluded from the study. Data were collected in a structured Performa. Data were analyzed in Microsoft Excel for descriptive statistics.
Results: A total of 161 ERCP procedures were performed during the study duration, of which 84(52.2%) were in males while 77(47.82%) were in females; the mean age was 54.82 ± 15.83 years. Biliary Stent placement (51.6%) was the most commonly performed procedure followed by Biliary Stone extraction (22.4%). Failed ERCP accounted for 30(18.6%) cases. The main indication for ERCP was Obstructive Jaundice (65.8%) followed by Common Bile duct (CBD) stones (42.9%). The least common indication was Dilated Intrahepatic Duct (1.86%). Only 4 cases of minor bleeding were observed during the procedure which were controlled during the procedures. No major complications have been seen on follow-up.
Conclusion: Obstructive Jaundice is major contributor to ERCP’s being performed. It is a relatively safe procedure in the hands of an experienced operator.
Keywords: Obstructive Jaundice; Retrograde Cholangiopancreatography; Gallstones; Pancreatic Duct.
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Smith, JK, AG Acheson, JAD Simpson, J. Stewart, IJ Beckingham, CB Gornall, JP Williams, MH Robinson y CA Maxwell-Armstrong. "From Small Acorns – Developing a Laparoscopic Colorectal Surgical Service". Annals of The Royal College of Surgeons of England 90, n.º 7 (octubre de 2008): 606–11. http://dx.doi.org/10.1308/003588408x318110.
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INTRODUCTION Randomised controlled trials have shown that laparoscopic colorectal surgery is equal in terms of safety to open surgery. Benefits have been seen for length of stay, blood loss, immune suppression and analgesia requirements. The aim of this study was to assess the safety and feasibility of introducing laparoscopic colorectal surgery to our unit. PATIENTS AND METHODS Prospectively collected cases of all patients undergoing laparoscopic colorectal surgery between July 2003 and July 2007 were reviewed. RESULTS A total of 143 patients (75 males and 68 females) with amean age of 65.8 years (range, 21–95 years) underwent surgery. Laparoscopic resection for colorectal malignancy was performed in 93 patients (65%). The conversion rate for all cases was 14.7%. Mean operative time was 203 min (range, 100–400 min), with amean blood loss of 180 ml. The mean number of lymph nodes in malignant cases was 13.8 with clear resection margin in all but one case. The mean postoperative stay was 5.6 days (median, 4 days; range, 2–35 days). UKCCR standard for lymph node retrieval was achieved in 62.6% of cases. There were four postoperative deaths. The overall 30-day morbidity rate was 21.7%. The service is consultant-led with 9.8% of cases performed by senior trainees and 37% of procedures performed by two consultants. CONCLUSIONS Laparoscopic colorectal surgery is technically feasible and safe in our hands. Although operative time is longer, this is counterbalanced by shorter hospital stay. The results from this series support the findings of others and continuing development of this service.
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Gross, Daniel Jonathan, Michael C. Smith, Bardiya Zangbar-Sabegh, Kenneth Chao, Erin Chang, Leon Boudourakis, Muthukumar Muthusamy, Valery Roudnitsky y Tim Schwartz. "Challenge of uncontrolled enteroatmospheric fistulas". Trauma Surgery & Acute Care Open 4, n.º 1 (diciembre de 2019): e000381. http://dx.doi.org/10.1136/tsaco-2019-000381.
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IntroductionWith the popularization of damage control surgery and the use of the open abdomen, a new permutation of fistula arose; the enteroatmospheric fistula (EAF), an opening of exposed intestine spilling uncontrollably into the peritoneal cavity. EAF is the most devastating complication of the open abdomen. We describe and analyze a single institution’s experience in controlling high-output EAFs in patients with peritonitis.MethodsWe analyzed 189 consecutive procedures to achieve and maintain definitive control of 24 EAFs in 13 patients between 2006 and 2017. EAFs followed surgery for either trauma (seven patients) or non-traumatic abdominal conditions (six patients). All procedures were mapped onto an operative timeline and analyzed for: success in achieving definitive control, number of reoperations, and feasibility of bedside procedures in the surgical intensive care unit. The end point was controlled enteric drainage through a healed abdominal wound.ResultsThere was a mean delay of 8.5 days (range 2–46 days) from the index operation until the EAF was identified. Most EAFs required several attempts (mean: 2.7 per patient, range 1–7) until definitive control was achieved. Multiple reoperations were then required to maintain control (mean: 13). While the most effective techniques were endoscopic (1) and proximal diversion (1), these were applicable only in select circumstances. A ‘floating stoma’ where the fistula edges are sutured to an opening in a temporary closure device, while technically effective, required multiple reoperations. Tube drainage through a negative pressure dressing (tube vac) required the most maintenance usually through bedside procedures. Primary closure almost always failed. Twelve of the 13 patients survived.ConclusionAn EAF is a highly complex surgical challenge. Successful source control of the potentially lethal ongoing peritonitis requires tenacity and tactical flexibility. The appropriate control technique is often found by trial and error and must be creatively tailored to the individual circumstances of the patient.
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Roth, Martin M. "CCD spectrophotometry of extended PN: Observations at Wendelstein Observatory". Symposium - International Astronomical Union 180 (1997): 277. http://dx.doi.org/10.1017/s0074180900130955.
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Most of the existing flux data on galactic PN is based on measurements with scanners or photoelectric aperture photometers. Also, true global fluxes are not even available for many PNe in lines other than Hβ, and one has to rely on line intensities which have been derived from slit spectrometers. For extended, low surface brightness objects all of these instruments are not appropriate to derive reliable fluxes (see e.g. remark on NGC 7293 by O'Dell, this conference). As part of a PhD thesis a dedicated CCD camera for the Wendelstein Observatory 0.8m telescope has been developed (Roth 1990, 1993), optimized for flux-calibrated imaging through narrow-band interference filters with bandpasses down to 8å FWHM and a thermal control unit for central wavelength tuning. As a test, nebular and central star fluxes have been measured for NGC 2392, NGC 3242, NGC4361, and NGC 6210 in Hβ, HeII 4686, [OIII] 5007, and a continuum passband. The results for these bright objects are in agreement with the best references as compiled from the literature. A detailed comparison shows that the spatial extent of the nebula is now always considered correctly, based on the CCD image information and the curve-of-growth convergence of the surface photometry. The central star photometry is largely improved, in particular for high surface brightness PNe. Another advantage (which however was not important for the test objects here) is the technically easy removal of disturbing field stars within the radius of a faint, extended nebula. The use of very narrow bandwidth, thermally controlled filters proved to be beneficial in substantially reducing the sky and nebular continuum background contribution. From the nebular and central star fluxes, Zanstra temperatures have been derived. The cause of the observed Zanstra discrepancy (which is in accordance with several other determinations for the investigated objects) cannot be attributed to observational uncertainties. From the discussion of Unified NLTE model atmospheres (Gabler et al. 1991) and model fits to the central stars of NGC2392, NGC3242, NGC4361 (Méndez et al. 1988), and NGC6210 (McCarthy et al. 1990) the most likely explanation is a combination of two effects: EUV excess over currently predicted central star flux distributions, and leakage of UV photons from the nebula (see also Méndez et al. 1992).
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Kumar, Prakash y Dheeraj Kumar Palwalia. "Decentralized Autonomous Hybrid Renewable Power Generation". Journal of Renewable Energy 2015 (2015): 1–18. http://dx.doi.org/10.1155/2015/856075.
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Power extension of grid to isolated regions is associated with technical and economical issues. It has encouraged exploration and exploitation of decentralized power generation using renewable energy sources (RES). RES based power generation involves uncertain availability of power source round the clock. This problem has been overcome to certain extent by installing appropriate integrated energy storage unit (ESU). This paper presents technical review of hybrid wind and photovoltaic (PV) generation in standalone mode. Associated components like converters, storage unit, controllers, and optimization techniques affect overall generation. Wind and PV energy are readily available, omnipresent, and expected to contribute major future energy market. It can serve to overcome global warming problem arising due to emissions in fossil fuel based thermal generation units. This paper includes the study of progressive development of standalone renewable generation units based on wind and PV microgrids.
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MacLeod, C. D., H. L. Doyle y K. I. Currie. "Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system". Biogeosciences 12, n.º 3 (5 de febrero de 2015): 713–21. http://dx.doi.org/10.5194/bg-12-713-2015.
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Abstract. This article describes a potentiometric ocean acidification simulation system which automatically regulates pH through the injection of 100% CO2 gas into temperature-controlled seawater. The system is ideally suited to long-term experimental studies of the effect of acidification on biological processes involving small-bodied (10–20 mm) calcifying or non-calcifying organisms. Using hobbyist-grade equipment, the system was constructed for approximately USD 1200 per treatment unit (tank, pH regulation apparatus, chiller, pump/filter unit). An overall tolerance of ±0.05 pHT units (SD) was achieved over 90 days in two acidified treatments (7.60 and 7.40) at 12 °C using glass electrodes calibrated with synthetic seawater buffers, thereby preventing liquid junction error. The performance of the system was validated through the independent calculation of pHT (12 °C) using dissolved inorganic carbon and total alkalinity data taken from discrete acidified seawater samples. The system was used to compare the shell growth of the marine gastropod Zeacumantus subcarinatus infected with the trematode parasite Maritrema novaezealandensis with that of uninfected snails at pH levels of 7.4, 7.6, and 8.1.
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MacLeod, C. D., H. L. Doyle y K. I. Currie. "Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system". Biogeosciences Discussions 11, n.º 5 (28 de mayo de 2014): 7659–83. http://dx.doi.org/10.5194/bgd-11-7659-2014.
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Abstract. This article describes a potentiometric ocean acidification simulation system which automatically regulates pH through the injection of 100% CO2 gas into temperature-controlled seawater. The system is ideally suited to long-term experimental studies of the effect of acidification on biological processes involving small-bodied (10–20 mm) calcifying or non-calcifying organisms. Using hobbyist grade equipment, the system was constructed for approximately USD 1200 per treatment unit (tank, pH regulation apparatus, chiller, pump/filter unit). An overall accuracy of ±0.05 pHT units (SD) was achieved over 90 days in two acidified treatments (7.60 and 7.40) at 12 °C using glass electrodes calibrated with salt water buffers, thereby preventing liquid junction error. The accuracy of the system was validated through the independent calculation of pHT (12 °C) using dissolved inorganic carbon (DIC) and total alkalinity (AT) data taken from discrete acidified seawater samples. The system was used to compare the shell growth of the marine gastropod Zeacumantus subcarinatus infected with the trematode parasite Maritrema novaezealandensis with that of uninfected snails, at pH levels of 7.4, 7.6, and 8.1.
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Dvortsevoy, Alexander y Ilya Tikhonov. "Impact Analysis of Excessive Fuel Consumption on Technical and Economic Performance of Coal-Fired Co-Generation Units". Applied Mechanics and Materials 792 (septiembre de 2015): 433–38. http://dx.doi.org/10.4028/www.scientific.net/amm.792.433.
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The study sets the objective of overall overrun fuel separation into two components. The first one depends on changes in the electric load of the power unit. The second component is influenced by changes of the power unit controlled parameters. The separation leads to the adjustment of technical and economic performance of the power plant unit. These indicators show both the efficiency of the power unit and the overall plant.
Tesis sobre el tema "Technically controlled unit"
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Jönsson, Gabriel y Tobias Jönsson. "Organisatoriska aspekters koppling till teknisk skuld : En fallstudie om hur balansen av organisatoriska aspekter kan understödja kontrasterande perspektiv och påverka teknisk skuld". Thesis, Malmö universitet, Institutionen för datavetenskap och medieteknik (DVMT), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-44439.
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Digitaliseringen har inneburit en tilltagande komplexitet i organisationer, vilket föranlett skapandet av begreppet teknisk skuld. Likväl som organisationer försätter sig i ekonomiska skulder försätter sig organisationer i tekniska skulder. Tidigare forskning inom teknisk skuld visar på ett kunskapsgap gällande organisationsteoretiska aspekters eventuella påverkan på teknisk skuld. Baserat på detta så syftar studien till att undersöka antagandet gällande kontrasterande perspektiv på teknisk skuld mellan kommersiellt styrda och tekniskt styrda organisatoriska enheter. För att sedan utforska huruvida balansen av organisatoriska aspekter mellan enheter kan understödja en viss typ perspektiv och därmed inverka på organisationens faktiska ageranden, avvägningar och vägval i relation till teknisk skuld. Undersökningen grundas i en kvalitativ fallstudie där åtta intervjuer i fyra mjukvaruutvecklande organisationer genomförts. Studien visar på att perspektiven mellan enheter i denna undersökning skiljer sig åt en aning men att detta inte påverkar teknisk skuld i någon större utsträckning. Detta tack vare ömsesidig förståelse, god kommunikation, samsyn genom överordnade mål samt balans mellan makt och kultur. Kommersiella krafter tycks besitta något mer makt men undersökta bolag har samtidigt vägt upp detta genom en tydligt teknikfokuserad kultur. Vilket kan få organisationer att, om något, balansera en aning mer åt ett fokus på framtida hållbarhet och därmed gå miste om nutida affärsmöjligheter genom att undgå ett mer flexibelt och tillåtande förhållningssätt till teknisk skuld.Digitization has meant an increasing complexity in organizations, which has led to the creation of the concept of technical debt. Just as organizations incur financial debts the organizations incur technical debts. Previous research in technical debt sheds light on a knowledge gap regarding organizational aspects, which influence technical debt. Based on this, the study aims to examine the assumption regarding contrasting views on technical debt between commercially controlled and technically controlled organizational units. To then explore whether the balance of organizational aspects between units can support a certain type of perspective and thereby influence the organization's actual actions, trade-offs and decision-making in relation to technical debt. The study was created through a qualitative case study where eight interviews were conducted in four software developing organizations. The study shows that the perspectives between units in this survey differ slightly, but that this does not affect technical debt to any great extent. This thanks to mutual understanding, good communication, consensus through overriding goals and a balance between power and culture. Commercial forces seem to possess somewhat more power, but surveyed companies have at the same time offset this through a clear product- and technology-focused culture. Which may cause organizations to, if anything, balance a little bit more on future sustainability and thus miss out on current business opportunities by avoiding a more flexible and permissive approach to technical debt.
Libros sobre el tema "Technically controlled unit"
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Frass, Michael. The difficult intubation in the ICU. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0081.
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Airway management in the intensive care unit differs from conventional controlled settings such as general anaesthesia in the operating room (OR). Due to adequate patient preparation and positioning in the OR, endotracheal intubation is usually easy to perform. However, in the intensive care setting, endotracheal intubation is often difficult or impossible because patients are not prepared and intubation is immediately necessary without sufficient time for putting together technical and pharmaceutical equipment. As an alternative, non-invasive alternate airway management may be performed. Besides non-invasive ventilation via mask or helmet, the use of Combitube®, EasyTubeTM, and different types of laryngeal mask airway are described, in order to alleviate decision-making in emergency situations such as difficult intubation, vomiting and bleeding patients, small interincisor distance, etc.
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Vincent, Julian. Biomimetic materials. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199674923.003.0010.
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Biological materials present the conventional materials scientist with alternative ways of achieving durability, recyclability, and adaptability. Technical materials are commonly designed to resist the initiation of cracks; biological materials control disaster by initiating failure where it can be more closely controlled and the strain energy can be more easily absorbed, at the same time controlling shape so that stress concentrations are avoided in sensitive areas. Most materials are hydrated and soft, achieving stiffness by dehydration and mineralization. The low energy of the predominant hydrogen bonds allows relatively easy breakdown and recycling of the units of biological materials. Since most biological materials are metabolically accessible (obvious exceptions are keratins and wood) they can be recycled and repaired in situ, adapting the organism to changing circumstances internally and externally. At the molecular level, liquid crystallinity is a driving force.
Actas de conferencias sobre el tema "Technically controlled unit"
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Üşenmez, Serdar, Sinan Ekinci, Oğuz Uzol y İlkay Yavrucuk. "Application of a Fuzzy Logic Controller for Speed Control on a Small-Scale Turbojet Engine". En ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-27158.
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Having a small-scale turbojet engine operate at a desired speed with minimum steady state error, while maintaining good transient response is crucial in many applications, such as UAVs, and requires precise control of the fuel flow. In this paper, first the mathematical model of a Small-Scale Turbojet Engine (SSTE) is obtained using system identification tests, and then based on this model, a classical PI controller is designed. Afterwards, to improve on the transient response and steady state performance of this classical controller, a Fuzzy Logic Controller (FLC) is designed. The design process for the FLC employs logical deduction based on knowledge of the engine behavior and iterative tuning in the light of software- and hardware-in-the-loop simulations. The classical and fuzzy logic controllers are both implemented on an in-house, embedded Electronic Control Unit (ECU) running in real time. This ECU is an integrated device carrying a microcontroller based board, a fuel pump, fuel line valves, speed sensor and exhaust gas temperature sensor inputs, and starter motor and glow plug driver outputs. It mainly functions by receiving a speed reference value via its serial communication interface. Based on this reference, a voltage is calculated and applied to the fuel pump in order to regulate the fuel flow into the engine, thereby bringing the engine speed to the desired value. Pre-defined procedures for starting and stopping the engine are also automatically performed by the ECU. Further, it connects to a computer running an in-house comprehensive Graphical User Interface (GUI) software for operating, monitoring, configuration and diagnostics purposes. The designed controllers are used to drive a generic SSTE. Reference inputs consisting of step, ramp and chirp profiles are applied to the controllers. The engine response using both controllers are recorded and inspected. The results show that the FLC exhibits a comparable performance to the classical controller, with possible opportunities to improve this performance.
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Kemp, Petrus D. y Chris Nieuwoudt. "Operation and Control of the PBMR Demonstration Power Plant". En 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89359.
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A large interest in High Temperature Gas-cooled Reactors (HTGR) has been shown in recent years. HTGR power plants show a number of advantages over existing technology including improved safety, modular design and high temperatures for process heat applications. HTGR plants with closed loop direct cycle power conversion units have unique transient responses which is different from existing nuclear plants as well as conventional non-nuclear power plants. The operation and control for a HTGR power plant therefore poses new and different challenges. This paper describes the modes of operation for the Pebble Bed Modular Reactor (PBMR) demonstration plant. The PBMR demonstration plant is an advanced helium-cooled, graphite-moderated HTGR consisting of a closed loop direct cycle power conversion unit. The use of transient analysis simulation makes it possible to develop effective control strategies and design controllers for use in the power conversion unit as well as the reactor. In addition to plant controllers the operator tasks and operational technical specifications can be developed and evaluated making use of transient analysis simulation of the plant together with the control system. The main challenges in the operation and control of the reactor and power conversion unit are highlighted with simulation results. Control strategies in different operating regions are shown and results for the power conversion unit start-up transition and the loss of the grid connection during power operation are presented.
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Wei, Jie, Hideo Kubo y Junichi Ishimine. "Thermal Design and Packaging of a Prototype Refrigeration Cooling System for CMOS-Based MCMs". En ASME 2003 International Electronic Packaging Technical Conference and Exhibition. ASMEDC, 2003. http://dx.doi.org/10.1115/ipack2003-35156.
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Thermal design and packaging strategy of a prototype dual-loop vapor compression refrigeration cooling system, developed as a pilot model for thermal management of high performance CMOS based MCMs, is introduced in this paper. The cooling system was comprised of two separated refrigeration units providing low temperature cooling via a dual-path cooling module (evaporator) mounted on a CPU-MCM package. Cooling capacity for each refrigeration unit was controlled ranging from 250W to 2500W with a refrigerant evaporating temperature at −25 degree centigrade. The CPU-MCM mounted with the refrigeration cooling module was packaged on a system board assembly, together with other electronic devices. The assembly was accommodated into a dew-point control box where two dewpoint control units were operating in a redundancy to remove moisture and keep a dew temperature inside the box below −30 degree centigrade for completely preventing from condensation. Cooling redundancy was provided by both the refrigeration units and dual-path cooling module. The cooling module was redundant in that two sets of refrigerant passages were staggered within a thin copper plate, where each set was connected to a separated refrigeration unit. Apart from the robust system and steady operation, the configuration and operation mode also provided the cooling system a high power efficiency and much shortened starting time. Numerical simulations were also performed for investigating airflow and thermal characteristics, in a system board level inside the dew-point control box. Detailed predictions of airflow and temperature distributions were significantly helpful for improving and verifying practical system designs.
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van der Wijk, Volkert y Just L. Herder. "Active Dynamic Balancing Unit for Controlled Shaking Force and Shaking Moment Balancing". En ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28423.
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For a mechanism with many elements that needs to be shaking-force and shaking-moment balanced with a low addition of mass, a low addition of inertia, and a low addition of complexity, the use of actively computer-controlled balancing elements is promising. With these actively controlled elements the net reaction forces and the net reaction moments to the base of the mechanism can be balanced directly instead of balancing each mechanism element separately as is common practice for passive balancing. Adaptability of the control also allows balancing of (variable) payload. This paper presents the concept of an active dynamic balancing unit, which is a unit that is mounted on unbalanced mechanisms and is controlled such that the combined system is dynamically balanced. The conceptual design and possible control strategies of such a unit, including pick-and-place motion of variable payloads, is studied. A simulation is presented to give insight in the possibilities and limitations of active dynamic balancing.
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Pai, Shantaram S. y David S. Riha. "Model Verification and Validation Concepts for a Probabilistic Fracture Assessment Model to Predict Cracking of Knife Edge Seals in the Space Shuttle Main Engine High Pressure Oxidizer". En ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-70132.
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Physics-based models are routinely used to predict the performance of engineered systems to make decisions such as when to retire system components, how to extend the life of an aging system, or if a new design will be safe or available. Model verification and validation (V&V) is a process to establish credibility in model predictions. Ideally, carefully controlled validation experiments will be designed and performed to validate models or submodels. In reality, time and cost constraints limit experiments and even model development. This paper describes elements of model V&V during the development and application of a probabilistic fracture assessment model to predict cracking in space shuttle main engine high-pressure oxidizer turbopump knife-edge seals. The objective of this effort was to assess the probability of initiating and growing a crack to a specified failure length in specific flight units for different usage and inspection scenarios. The probabilistic fracture assessment model developed in this investigation combined a series of submodels describing the usage, temperature history, flutter tendencies, tooth stresses and numbers of cycles, fatigue cracking, nondestructive inspection, and finally the probability of failure. The analysis accounted for unit-to-unit variations in temperature, flutter limit state, flutter stress magnitude, and fatigue life properties. The investigation focused on the calculation of relative risk rather than absolute risk between the usage scenarios. Verification predictions were first performed for three units with known usage and cracking histories to establish credibility in the model predictions. Then, numerous predictions were performed for an assortment of operating units that had flown recently or that were projected for future flights. Calculations were performed using two NASA-developed software tools: NESSUS® for the probabilistic analysis, and NASGRO® for the fracture mechanics analysis. The goal of these predictions was to provide additional information to guide decisions on the potential of reusing existing and installed units prior to the new design certification.
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Song, Seungmoon, Young-Jae Ryoo y Dennis W. Hong. "Development of an Omnidirectional Walking Engine for Full-Sized Lightweight Humanoid Robots". En ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-48786.
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In this paper, we propose and demonstrate an omnidirectional walking engine that achieves stable walking using feedback from an inertial measurement unit (IMU). The 3D linear inverted pendulum model (3D-LIPM) is used as a simplified model of the robot, the zero moment point (ZMP) criterion is used as the stability criterion, and only the feedback from the IMU is utilized for stabilization. The proposed walking engine consists of two parts; the omnidirectional gait generator, and the stability controller. ZMP equations, derived based on the 3D-LIPM, are used in the omnidirectional gait generator. The solutions of the differential equations are directly used which reduces the computation cost compare to other existing methods. Two kinds of feedback controllers are implemented for the stability controller; one is the indirect reference ZMP controller, and the other is the indirect joint controller. The walking engine is tested on a lightweight, full-sized, 21-degree-of-freedom (DOF) humanoid robot CHARLI-L (Cognitive Humanoid Autonomous Robot with Learning Intelligence, version Lightweight) which stands 141 cm tall and weighs only 12.7 kg. The design goals of CHARLI-L are low development cost, lightweight, and simple design, which all match well with the proposed walking engine. The results of the experiments present the efficacy of our approach.
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Liu, Miaomiao, Ming Liu, Shuran Zhao, Gege Song y Junjie Yan. "A Novel Coal-Fired CHP System Integrated With Steam Ejectors to Realize Heat-Power Decoupling and Energy Saving". En ASME 2020 Power Conference collocated with the 2020 International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/power2020-16467.
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Abstract Traditional combined heat and power (CHP) units should run in the heat-controlled mode. The adjustable range of power load is restricted by the heat load, and the minimum power load increases with the heat load. Because of high penetration of intermittent renewable power, operational flexibility of CHP units is highly required. It is necessary to adopt some technical solutions to realize heat-power decoupling for CHP units. To find a heat-power decoupling method with low investment and high energy efficiency, the steam ejectors, simple in structure and low in cost, are applied to design a novel heat-power decoupling system in this study. Steam ejectors can recover the waste heat of exhaust steam of steam turbines. Therefore, the integration of steam ejector may realize heat-power decoupling and energy saving simultaneously. Three heat-power decoupling systems with steam ejectors are designed. The heat-power decoupling performance and energy consumption characteristics of these systems are investigated with a reference 330 MW coal-fired CHP unit. Results show that all three modified systems can realize heat-power decoupling. The heat-power decoupling performance of improved system III is the best, and improved system I has the least coal consumption rate for power generation.
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Grönman, Aki, Juha Honkatukia, Petri Sallinen, Jari Backman, Antti Uusitalo, Teemu Turunen-Saaresti y Ahti Jaatinen-Värri. "Design and Performance Measurements of a 6 kW High-Speed Micro Gas Turbine Prototype". En ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42620.
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Small portable electricity generating systems are suitable in remote locations where the access by vehicles is restricted or not even possible. These kind of places include for example catastrophic areas after earthquakes or tropical cyclones. Such machines can also be used as auxiliary power units in motor or sail boats. Gas turbine based electricity generation systems offer a good alternative for typical engine-generator units which are characterized by lower specific powers. It is suggested that the power to weight ratio of a 6 kW micro gas turbine can be more than eight times higher than that of the corresponding engine-generator unit. The biggest drawback is the higher specific fuel consumption; however, by introducing a recuperator, the specific fuel consumption can be improved. In this article, the design process and experiments of a 6 kW micro gas turbine prototype are described and discussed in detail. The built non-recuperated prototype is based on a commercial, small jet engine originally designed to give thrust to radio controlled model airplanes. The jet nozzle of the jet engine was replaced by an axial power turbine which was directly connected to a small, high speed permanent magnet generator. The experiments showed the potential of the prototype.
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Pennacchi, P., S. Chatterton y A. Vania. "Modeling of the Dynamic Response of a Pelton Turbine Hydroelectric Plant". En ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45907.
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The paper presents a detailed numerical model of the dynamics of a Pelton turbine installed in a hydroelectric plant. The model considers in detail the Pelton turbine with all the electromechanical subsystems, such as the main speed governor, the controller and the servoactuator of the turbine nozzle, and the electric generator. In particular it reproduces the effects of pipe elasticity in the penstock, the water inertia and the water compressibility on the turbine behaviour. The dynamics of the surge tank on low frequency pressure waves is also modeled together with the main governor speed loop and the position controllers of the nozzle needle actuators and of the hydraulic electrovalve. Model validation has been made by means of experimental data acquired during some starting tests after a partial revamping of a hydroelectric unit, which involved also the control system of the hydraulic actuators but not the nozzles. The model is used in order to identify the cause of the oscillations of the electric power mainly ascribed to the backlash of the nozzle needle system.
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Vantsevich, Vladimir V., Jesse R. Paldan y Jeremy P. Gray. "A Hybrid-Electric Power Transmitting Unit for 4x4 Vehicle Applications: Modeling and Simulation". En ASME 2014 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/dscc2014-5855.
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In this paper, a technical concept is described for a hybrid-electric power transmitting unit (HE-PTU) to control the split of power between the drive axles of a 4×4 hybrid-electric vehicle. This new power transmitting unit is a mechatronic systems by its design and uses a planetary gear set and eddy current brake to provide a continuously variable (dynamic) gear ratio that can be integrated into the vehicle driveline between the transfer case and front axle. The paper details the electrical and mechanical characteristics of the device, including its various operation modes, its mathematical model built from the equations of the planetary gear set and eddy current brake, an optimization condition by which the device will be controlled to improve vehicle energy efficiency, as well as its torque and electrical current usage. Computer simulations are performed on a mathematical model of a 4×4 military truck using the power transmitting unit in conjunction with a series hybrid-electric configuration transmission.
Informes sobre el tema "Technically controlled unit"
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Oilwell Power Controller (OPC Unit). Technical report. Office of Scientific and Technical Information (OSTI), septiembre de 1993. http://dx.doi.org/10.2172/10177946.
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