Full Power Research Articles

Multi-code estimation of DTT edge transport parameters

The main goal of the Divertor Tokamak Test facility (DTT) is to operate with a high value of power-exhaust-relevant parameter P S O L /R in plasma scenarios similar to those foreseen for the Demonstration Fusion Power Plant (DEMO) in terms of low collisionality and neutral opacity. For these unique characteristics, accurate modelling of the principal scenario is necessary for machine designing. In edge numerical codes, cross-field transport profiles have a high impact on modelling results. This work aims at providing a coherent set of transport parameters for DTT full-power (FP) single-null (SN) scenario edge modelling. To evaluate such parameters for DTT, a transport analysis on the current machine has been performed using SOLEDGE2D-EIRENE and SOLPS-ITER. The transport parameters to be used in the simulations of the DTT single-null scenario were selected using two complementary methods. The first is the modelling of JET and Alcator C-Mod (C-Mod) with SOLEDGE2D-EIRENE and SOLPS-ITER, validating transport parameters by comparing modelling results to experimental data from pulses which are considered DTT-relevant . JET pulses were selected with the highest auxiliary input power (from 29 to 33 MW), plasma current and toroidal field to better match DTT parameters; nitrogen and neon seeded pulses were selected to check possible seeding material dependencies. The considered C-Mod pulse better matches DTT plasma density and neutral opacity. Transport parameters are then scaled to DTT according to scaling laws. The second method derives the transport parameters by tuning their values inside the DTT separatrix to reproduce the pedestal profiles predicted by the EPED model via the Europed code and applied in DTT. The derived set of DTT transport parameters is consistent with the results obtained by modelling present machines, reproduces the expected heat flux decay length in detached conditions and, inside the separatrix, reproduces the predicted pedestal using transport parameters which are coherent with what is predicted by the quasi-linear turbulent model QuaLiKiz. • Edge and divertor transport parameters of the DTT single-null scenario were studied. • The edge transport parameters of JET and C-Mod pulses were derived by SOLEDGE2D-EIRENE and SOLPS modelling. • Transport parameters were scaled from present machines to DTT. • First principles core modelling with JETTO confirms the validity of the previous estimations.

Hybrid Integration of Chips Using SISL for Ka-Band High Combining Efficiency Power Amplifier

Hybrid integration of millimeter-wave (mm-wave) chips for power combining amplifier using substrate-integrated suspended line (SISL) is studied for the first time in this letter. A bond wire compensation structure with small size, wide bandwidth, and cavity mode suppression is proposed, and the wire bonding interconnect obtains the bandwidth of 0–48 GHz. A power combining amplifier based on this structure is proposed and the heat dissipation optimization is carried out. Finally, a four-way full Ka-band spatial power combining amplifier with high combining efficiency is fabricated. From 26 to 40 GHz, the maximum output power at the 1-dB compression point is 31 dBm, and the power combining efficiency is 78%–93%.

“[A] time / Of pell-mell havoc and confusion”: Shakespeare and the 2016 Paris Protests

Abstract: This article looks at several graffiti based on translated quotations from Shakespeare’s plays which appeared on the walls of Paris in the spring of 2016, during the many protests against the government’s proposed labor law. After a discussion of Shakespeare’s own sense of the importance of visual communication strategies and painterly media in times of insurrection, it then moves on to the particularly tense political context in which these French graffiti were staged on the city surfaces. Based on detailed descriptive coding of these acts of writing, this article analyzes them as a modality of radical performance, showing that these words from The Tempest or Romeo and Juliet were staged as part of a visual political theater, and thereby allowing audiences to rediscover the full affective power and scope of such graffiti. The article finally turns to a close reading of the translated quotations in order to better grasp their time/site-specificity and topical relevance. Considering the parallel occupation of Paris’s main theaters at the time, it reassesses the growing gap between theater and protest as well as between performance and drama, while trying to account for Shakespeare’s ubiquitous presence in such contemporary discussions.

Reflection power suppression for solid state amplifiers with combiner optimization.

The application of high-power solid state amplifiers (SSAs) in accelerator facilities is increasing, and equipment failure caused by reflected power is the main risk to their long-term operation. High-power SSAs often comprise multiple power amplifier modules. Full power reflection is more likely to damage the modules in SSAs if the amplitudes of the modules are unequal. Optimization of the power combiners is an effective means for improving the stability of SSAs under high power reflection. This study analyzes the mechanisms and conditions of reflected power generation using the scattering parameters of the combiner and proposes an optimization scheme for the combiner. The simulation and experimental results show that some modules may receive reflected power as high as nearly four times the rated power of one module when the SSA meets certain conditions, which could damage the modules. The maximum reflected power can be effectively reduced and the anti-reflection ability of SSAs can be improved by optimizing the combiner parameters to suppress the maximum reflected power.

The Hermits of Big Sur by Paula Huston

Reviewed by: The Hermits of Big Sur by Paula Huston Judith Sutera OSB The Hermits of Big Sur. By Paula Huston. Collegeville, MN: Liturgical Press, 2021. 235pp. $24.95. This is not a book about some romanticized characters who fit the world’s image of hermits, but about a real-life Roman Catholic community of Camaldolese hermits, a subset of the Benedictines, the oldest religious institution within the church. The book starts exactly where it should, with the question of why in the world anyone would take up the life of a hermit. Huston ably distinguishes between “fuga mundi,” a conscious flight from the world for a positive purpose and “contemptus mundi,” an attempt to escape the world because it is seen as evil. The hermit must be motivated by fleeing towards rather than fleeing from. Huston sets the stage for the Big Sur community by placing it firmly within its geographical environment. She makes the important connection between this religious settlement of the 1950s and the local world of author Henry Miller, resident artists, World War II veterans [End Page 85] seeking meaning and healing, and others drawn to the “grandeur and nobility of the setting” as Miller put it. Huston writes, “But Big Sur is not only astonishingly beautiful; it also manifests what the nineteenth-century British Romantics would call ‘the Sublime.’ By this term, they meant that the full power of uncontrolled nature is on display, and humans can only stand before the spectacle in awe” (7). Eventually, the monks would share this wild coastal land with the neighboring Esalen Institute, where people seeking meaning and mystery in this powerful natural setting would include Alan Watts, Aldous Huxley, LSD experimenters, and other mid-century thinkers. “The New Age movement, alternative medicine, East-West religious dialogue, yoga, massage, mind-body interventions, Joseph Campbell’s archetypes, and Fritz Perl’s Gestalt therapy owe much of their widespread practice today to the impressive lineup of radical thinkers who passed through Esalen during the revolutionary sixties. Like the psychedelic revolution, the Esalen phenomenon was also prompted by a kind of fuga mundi” (9). Some of these practices have even cross-pollinated with the very different world of their Camaldolese neighbors. Meanwhile, the monks were drawn to this place by their own contemporaneous search for meaning and a home for their contemplative life. The bulk of this book is not about a small group of men and the home they created but about the context in which they created it. The story is solidly situated within substantial descriptions of world history and Italian politics, especially the period of Mussolini and the love/hate relationship of fascism and the church. Given the world portrayed here, it is no wonder that a 1958 Time magazine featuring the Italian monks who came to look for a foundation place claimed they already had twenty potential applicants. But it is rare that a religious community is ever founded in harmony. The book follows correspondence with famous Trappist monk Thomas Merton and the many challenging matters around the early years, especially the turmoil within the church in that time of reform and renewal that divided communities and brought pain to many individuals. This monastery, as are so many, was born in the conflicting views of the kinds of people who dare to create, and the tension between human personalities, between ideal and institution. I have personally experienced the grace and goodness of this unique sacred place and have known some of the monks; this book helped me to see all of it in a much broader and deeper way. As a monastic religious myself, I commend the author on her ability to capture both the practical, historical dimensions and the indefinable power of this place and the people who created and live in it. I believe, too, that a story about such an unusual lifestyle told in this way might engage the minds [End Page 86] and hearts of people who know little about the world of religious hermits. Judith Sutera OSB Mount St. Scholastica Copyright © 2023 American Catholic Historical Society

Thermal stability of differently rolled pure tungsten plates in the temperature range from 1125 °C to 1250 °C

Application of rolled tungsten as armor of plasma-facing components in future fusion reactors requires its deformation-induced microstructure remaining stable during operation. At high operation temperatures, restoration processes as recovery, recrystallization and grain growth will unavoidably embrittle ductile tungsten achieved by rolling. Three pure tungsten plates manufactured by unidirectional rolling or cross-rolling in two different manners were qualified as baseline material for DEMO. To investigate their thermal stability, hardness testing is performed after isothermal annealing in the temperature range between 1125 °C to 1250 °C. The recrystallization kinetics of the different plates (and different regions within them) is analyzed thoroughly to allow extrapolation outside the investigated temperature range. Significant differences between the recrystallization kinetics of the three tungsten plates originate from the microstructure established by rolling. Two of the plates showed pronounced local differences in their recrystallization kinetics with the core of the plates recrystallizing ahead of the edge regions closest to the rolls. The third plate exhibits best thermal stability without notable differences between the local recrystallization kinetics. Where the two former plates may survive operation for two full power years only at temperatures less than 1005 °C, the later plate could sustain 1035 °C for the same period.

Conceptual design of the double tube burnable poison for the next generation small modular reactor

In this study, a new application of an innovative burnable poison (BP), which is called Double Tube Burnable Poison (DTBP), is introduced. Two design cincepts of the DTBP were tested in a small modular reactor (SMR) to achieve a longer operating cycle with low soluble boron concentration. These two concepts can be loaded in different locations in the fuel assembly, which increases the degree of freedom of nuclear design. The flexibility of this design allows it to increase its poison effect with the ability to control the depletion speed of its absorber materials. The DTBP pins were combined with the Erbia pins to achieve a flat k-infinite letdown curve with a significant reduction of the excess reactivity. The assembly and core calculations were performed by DeCART2D and MASTER codes. The results showed that the combination of DTBP and Erbia core achieved a cycle length of more than 3.5 Effective Full Power Years. Also, the highest value of Critical Boron Concentration was reduced to 309 ppm within the design limitations of the moderator temperature coefficient and the maximum pin power peaking. The performance of this option is the best among the other options including the conventional BP designs.

Вплив конструктивних параметрів термоплати на гістерезис за тепловим навантаженням

The contact heat exchangers designed to remove heat from the cooled devices are used in mechanically pumped two-phase loops of thermal management systems for ground and space applications, a thermoplate (heat sink). After the device is turned on, it may overheat abnormally during the process of reaching a stationary operating mode. Overheating is associated with the phenomenon of thermal load hysteresis during the onset of boiling, the transition from single-phase convection to developed boiling in the evaporator of a heat sink material. This work studied the influence of the construction parameters of thermoplate on the hysteresis phenomenon at the integral level. For this purpose, a thermoplate testing methodology was implemented, which includes experiments with slow (quasi-stationary) and quick heating after turning on the device immediately at full power. Overheating of the device is possible during both "slow" and "quick" heating. The maximum overheating in the experiments performed was ~18 K. Such overheating can pose a danger to the reliability of the device. The study was performed with ammonia as a coolant on 5 models of thermoplate that differ in evaporator channel roughness, length, material, longitudinal thermal conductivity, the heat capacity of the structure, etc. The danger of overheating the device is also determined by the maximum thermal load at which the device is operated. The following conclusions were made: the greatest influence on the hysteresis parameters is the value of the evaporator channel surface roughness. Increasing the roughness reduces the risk of overheating the device, and changes the nature of the "boiling curves" in the thermoplate; an increase in the length and longitudinal thermal conductivity has a favorable effect on reducing the risk of overheating; the evaporator surface is made of aluminum alloy instead of stainless steel, which makes hysteresis impossible; in the case of rapid heating of the thermoplate, the maximum heat flux at steady-state has an ambiguous effect: with its increase, overheating due to hysteresis first increases, and in the case of further increase, it decreases and may disappear altogether. A significant increase in the maximum heat flux compared to the heat flux at the beginning of boiling reduces the danger of hysteresis affecting the overheating of the device. The results of this work provide recommendations on how to avoid the dangerous overheating of the device due to the hysteresis phenomenon.

ON THE QUESTION OF THE HISTORY AND ROOTS OF LITERARY POSTMODERNISM (BASED ON THE MATERIALS OF THE APOLOGISTS OF THE ARTISTIC DIRECTION)

Russian and world literature and culture history as a whole is now being rethought in line with the complete technical replacement of all natural with artificial. There is no exaggeration in this process. A new round (or stage) of literature, culture and art differs from all the previous ones by the probability of the disappearance of former aesthetic values and ideals. Russian critic, for example, the well-known modern critic Y.Borev, linking this issue, which is disastrous for all mankind, with the deep subconscious of the individual, was forced to state that “a person today can no longer withstand the pressure of the world and becomes a kind of post-human” [1, p.311]. And according to another authoritative apologist of literary postmodernism, B. Watels, “the omnipresence of modern technologies puts pressure on people's consciousness, while forming a special techno-culture, because in order to fully use the full power of these technologies, people should strive to change their consciousness as much as possible. Otherwise, they have a real risk of becoming post-humans” [5, p.53]. In these statements, we see how two critics of different nationalities come to a single decision. Russian literary postmodernism is linked by genetic ties with various technogenic processes and such a technical take-off did not exist in the previous decades, when modernism was gaining strength in the first place. In this regard, it is necessary to highlight the prefix “-post”, which over time has already taken on a fundamentally different meaning compared to modernism itself. Moreover, the very thinking of the people of the XXI century has changed dramatically. On the one hand, it turned out to be subordinate to technology in general. On the other hand, postmodernism, unlike its previous stages, has developed (although not in its final form) own signs and criteria of writing.

Prioritizing taxa for genetic reference database development to advance inland water conservation

Biodiversity loss has accelerated over the past century and freshwater species overall are among those experiencing greatest declines. Genetic resources have the potential to help evaluate the full magnitude of this loss and represent a key tool to effectively allocate conservation resources and monitor the success of restoration efforts. The full power of genetic resources will be realized when the daunting task of referencing all DNA sequences of freshwater organisms is complete. Here, we quantified the availability and distribution of barcode and genome data for freshwater macroscopic organisms in Canada, a country rich in inland water resources and thus particularly vulnerable to aquatic species losses. Impressively, most inland water species (86 %) were represented by barcodes recorded in the BOLD Systems database, while very few had full genomes available (<4 %) in the NCBI database. We identified barcode data deficiencies in northern regions and for taxa assessed as most at risk or without sufficient information for conservation status classification. As expected, the speciose insect group had a lower-than-average number of records per species and a high proportion of data deficient species without adequate barcode coverage. This study highlights where future sequencing resources should be prioritized within initiatives such as the Canada BioGenome Project and BIOSCAN Canada and provides a workflow that could be applied internationally to inform conservation management plans and to mitigate biodiversity loss.

Transition Core Modeling for Extended-Enrichment Accident-Tolerant Fuels in Light Water Reactors Using PARCS/Polaris

Current plans and efforts of reactor operators and vendors to include extended-enrichment (EE) fuel and accident-tolerant fuel (ATF) in current reactor fleets motivate the study of these changes in reactor physics analysis. This work uses the U.S. Nuclear Regulatory Commission’s core simulator PARCS to do the core calculation and the SCALE Polaris lattice physics code to generate the homogenized, few-group constants. In this work, both pressurized water reactor and boiling water reactor (BWR) colorset models are used to verify the proposed approach. The accuracy presented in the colorset models verified the capability of the PARCS/Polaris procedures for the transition core analysis in light water reactors. For the whole-core calculation, the ATF and EE-ATF transition core models were incorporated, in addition to the nominal core model. The BWR model was chosen to represent the entire core calculation due to its challenging design. The core parameters studied are the core power distribution, power peaking factor, Doppler temperature coefficients, and control rod worth at cold zero power and hot full power. When the core parameters of the transition cores are compared with those of the nominal core in PARCS, the results suggest that there is no drastic change in the core parameters for the implementation of ATF and EE fuels.

CorTAF: A nuclear reactor core three-dimensional thermal-hydraulic characteristics analysis code based on OpenFOAM

In this paper, a thermal hydraulic analysis method based on open source CFD platform OpenFOAM was proposed. The models of coolant flow and heat transfer, fuel rod heat conduction and coupled heat transfer were established according to the bundle structure characteristics of PWR core, and then a nuclear reactor three-dimensional thermal–hydraulic characteristics analysis code CorTAF was developed based on finite volume method with the spatialresolution of subchannel level. The international benchmarks, including GE3 × 3, Weiss and PNL2 × 6 fuel assembly flow and heat transfer experiments, were selected to carry out the validation. The calculation results were basically consistent with the experimental data, illustrating that CorTAF is suitable for predicting the flow and heat transfer characteristics of coolant in the rod bundle fuel assembly. The thermal–hydraulic characteristics of fuel assembly and PWR core under full power operation and blockage accident conditions were simulated using CorTAF. The steady-state and transient spatial distribution of physical quantities in subchannel-scale including coolant and fuel rod temperature were obtained, and the influence of blockage condition on flow and heat transfer characteristics was analyzed. This work has reference significance for the development of core thermal hydraulic analysis tools for PWR.

Comparison of Emissions and Efficiency of Two Types of Burners When Burning Wood Pellets from Different Suppliers

Wood pellets play an important role among biomass materials used as fuel. At the same time, today’s economic, environmental, political and social realities, as well as other circumstances related to fuels used for heat generation, mean that there is demand for increasingly efficient and environmentally friendly combustion sources. As is well known, each combustion source has a different efficiency due to its intended use, design, principle of operation and the type and composition of the fuel burned. The amount of pollutants emitted into the environment during combustion also largely depends on these factors. The aim of this study was to compare the flue gas emissions and efficiency of two pellet burners of different design, burning certified A1 wood pellets from different suppliers. The emission requirements were met during the combustion of wood pellets in a boiler with the two burners tested (one with a moving grate and an overfed burner). The analyses and studies carried out aim to improve the capability of managing the efficiency and environmental performance of the heat source (i.e., a boiler or a burner) and the fuel (type of wood pellets). This is done in the context of demonstrating a better combustion source when selecting the right burner and fuel in terms of efficiency and emissions. In this paper, comparisons of flue gas emissions are presented along with characteristics in the form of graphs, as well as thermal and combustion efficiencies for the corresponding solid fuel used in the form of wood pellets. After comparing the emissions, it was found that the statistical averages of CO, NOx, dust and VOCs were similar for combustion at full power using the burners tested. Taking into account the pollution levels at combustion, it can be said that the difference in CO emissions at full and minimum combustion is lower for the experimental burner compared with the moving grate burner (reference burner). In summary, it can be concluded that the experimental overfed burner under consideration can be successfully used as a solid fuel boiler to burn wood pellets.

Experimental study of chemical-etched high-power cladding mode stripping device toward high attenuation

Fiber cladding mode stripping device with high-power high-attenuation stripping capability and negligible perturbation to signal light has been developed by employing Teflon-capillary segmental-etching fabrication method. By using different etchant solutions, surface roughening and cladding reducing structures can be obtained. The influence of the roughened length on the attenuation of cladding power has been studied experimentally, showing that roughened surface strips cladding light well at length below 5 cm, but becomes less effective beyond that. The impact of the cladding reduction has also been investigated, indicating that reduced cladding can help deplete the cladding light effectively, and the attenuation is able to be improved from 23.0 dB to 43.2 dB by etching the cladding diameter from 400 μm to 50 μm. By combining the roughened surface and reduced cladding structures, cladding mode stripper with 7 °C/kW of temperature rising rate on the etched area has been made, and stripped power up to 2.1 kW at 39 dB of attenuation has been demonstrated, with the device length merely 16 cm. The maximum temperature on the device housing at full operation power for the case water flux being 3.1 L/min and 5.6 L/min is 67 °C and 50 °C, respectively. To the best of our knowledge, this is the first report of >2-kW power cladding mode stripping device with 39-dB attenuation. All results indicate the effectiveness of the proposed fabrication technique to make cladding mode stripping device for high power and superior beam quality fiber laser systems.

Burnup Characteristics of Transuranic Fuel With Burnable Poison in Dual Cooled Annular Rod of VVER-1000

Abstract The potentiality of Transuranic (TRU) fuel as dual cooled annular fuel rods with different types of burnable absorbers (BAs)- integrated burnable absorbers (IBAs), burnable poison rods (BPRs), coated absorbers, etc. in the hexagonal assembly of VVER-1000 was studied. Annular 7, Annular 8, and Annular 9 models were taken for various combinations of TRU fuel and BAs. Planned models were simulated in Monte Carlo particle simulation code OpenMC and lattice physics deterministic code Dragon Version5. Burnup-dependent multiplication factors (MFs) were simulated for 3000 effective full power days (EFPDs). Reactivity was calculated by taking 3% neutron leakage. The study showed that both the MF and reactivity for TRU fuel are significantly higher than conventional UO2 fuel. Linear reactivity model (LRM) was applied to find out cycle burnup, discharge cycle burnup, and cycle length. High cycle burnup, discharge burnup, and cycle length have been observed for TRU fuel compared to UO2 fuel. Burnup-dependent atomic concentration graphs showed that slight burn of Np-237, constant concentration for Cm-244, a slight increase for Am-242, and linear burnout of BAs- Gd-155, Gd-155, and Er-167. A lower concentration of Xe-135 has been observed for TRU fuel. Pin power distribution and energy-dependent neutron flux for different models and BAs combinations are also included in this study.

Thermal Performance Optimization of Multiple Circuits Cooling System for Fuel Cell Vehicle

Due to its advantages of high efficiency, high power density at low temperature, fast start-up and zero emission, fuel cells are of great significance in automobile drive application. A car powered by electricity generated by an on-board fuel cell device is called a fuel cell vehicle (FCV). Fuel cells have a large demand for heat dissipation, and the layout space of automotive cooling modules is limited. Based on this situation, a parallel arrangement of multiple radiators is proposed. Using numerical simulation means to verify and optimize the designed multiple circuits cooling system (MCCS), from the original layout scheme based on the Taguchi method to establish the objective function of the reliability design of the MCCS, select A2/B1/C1/D2/E1/F1. In the scheme, the outlet temperature of the fuel cell is finally reduced to 75.8 °C. The cooling performance is improved, and the spatial layout of the individual cooling components can also be optimized. The whole vehicle experiment was carried out under four working conditions of full power idling charging, half power idling charging, constant speed of 40 km/h and constant speed of 80 km/h, to verify the cooling performance of the MCCS and to prove the effectiveness of the MCCS designed in this paper.

Calculation of AC Losses in a 500 kJ/200 kW Multifilamentary MgB2 SMES Coil

SMES technology based on MgB2 superconductor and cryogenic-free cooling can offer a viable solution to power-intensive storage in the short term. One of the main obstacles to the development of dry-cooled SMES systems is the heat load removal due to the AC loss of the superconductor during fast charging and discharging cycles at high power. Accurate knowledge of the amount and distribution of AC loss in the coil is of paramount importance for the sizing and the design of the cooling system and for assessing the possible operational limits of the technology. In this manuscript, the AC loss of a 500 kJ/200 kW multifilamentary MgB2 SMES during charge–discharge cycling at full power is numerically investigated. The methodology and assumptions of the calculation are briefly resumed, and numerical results are reported and discussed in detail. In particular, the time profile and the distribution of the dissipated power all over the coil are reported. An average dissipation of 85.5 mW/m is found all over the coil during one charge–discharge cycle at full power, with a peak of 150.1 mW/m in the turns lying at the ends of the coil.

Multiport Control With Partial Power Processing in Solid-State Transformer for PV, Storage, and Fast-Charging Electric Vehicle Integration

This article proposes a multiport control method to enable partial power processing (PPP) in a medium-voltage (MV) multiport solid-state transformer (SST). MV multiport SSTs are promising in integrating low-voltage dc sources or loads such as solar photovoltaic, energy storage, and electric vehicles into smart grids without bulky line-frequency transformers. Compared with voltage-source SST, current-source (CS) SST features single-stage isolated bidirectional ac/ac, ac/dc, or dc/dc conversion using an inductive dc link. For a multiport CS SST, it is revealed in this article that the PPP capability can be enabled through the proposed control without extra hardware, different from the case of voltage-source converters where special hardware architecture is required for the PPP. With the PPP, most power exchange between LV ports is processed by only a fraction of the entire conversion stage, leading to reduced dc-link current, volume, loss, and improved efficiency. The proposed multiport PPP control scheme is analyzed to verify the advantages across a wide voltage and power range against conventional full power processing (FPP) multiport control, using the soft-switching SST (S4T) with reduced conduction loss as an example. Comparative experimental results based on a SiC three-port S4T prototype verify the effectiveness of the proposed PPP scheme against the FPP scheme under both steady state and dynamic conditions. The dc-link current reduction is measured to be more than 36%. Significantly, the proposed multiport PPP control scheme is generic and applicable to any hard-switching or soft-switching CS SSTs without extra hardware.

Gain scheduling control of aero-engine based on mixing polynomial LPV synthesis

Abstract A full envelope LMI-based multi-region linear parameter-varying power controller is designed for a turbofan engine in this paper. According to the characteristics of aero-engine model, three scheduling variables are divided into two groups firstly, and then part of them are partitioned, rather than all scheduling variables are partitioned directly as the usual multi-region LPV control. The polynomial LPV model of aero-engine is established under a specific flight condition. An explicit LPV controller by gridding method based on parameter-dependent Lyapunov function is designed and we propose a method to eliminate the dependence of LPV controller on the derivative of scheduling parameter. The flight envelope of turbofan engine is divided into multiple sub-regions, and a mixing LPV control method with overlapping regions is proposed, which can guarantee stability and performance across the full envelope. Finally, the simulation results on the nonlinear component level model of a twin-spool turbofan engine verify our method.

Integration studies of RF solid-state generators in the electrical system of NBTF experiments and ITER HNB

SPIDER operation, started in 2018, pointed out performance-limiting issues caused by the technology employed in RF generators, based on tetrode free-running oscillators. One of these limits, namely the onset of frequency instabilities, prevented operation at the full rated power of 200 kW. In addition, tetrodes require high voltage to operate, which translates to risk of flashovers and the necessity to perform conditioning procedures, limiting the overall reliability. These disadvantages, combined with the positive experience gained in the meanwhile on smaller facilities with solid state amplifiers, led to the proposal of a complete re-design of the radiofrequency power supplies. This paper describes the modelling activities used to define specifications and design criteria of the solid-state amplifiers for SPIDER and MITICA, which can be directly transposed to the ITER HNB units when their functionality is proven. We detail the topology of the generators, consisting of class D amplifier modules combined to achieve the required 200 kW, which design is mainly driven by the necessity to deliver nominal power to the ion source, mitigate the risk of obsolescence, and improve the reliability through modularity. Due to the non-standard application, we gave particular focus to the integration of generators in the RF systems of SPIDER and MITICA. Numerical analyses were performed to verify the impact of harmonic distortion on transmission line and RF load components, to address the effect of mutual coupling between RF circuits on the generator output modulation, and to assess the magnitude of common mode currents in the electric system. These studies, as well as the experience gained from SPIDER operation, helped to define dedicated circuit design provisions and control strategies, which are currently being implemented in the detailed design and construction phase of the new RF amplifiers.