Miracle-dz/UniFAR-FTUs huggingface dataset:
Toward Self-Reliant Wind Farms

Large-scale integration of renewable energy generators, inverter-based resources and network interconnections into the grid brings forth a massive penetration of power electronic converters. This results in a highly dynamic environment that poses a risk to stability of system voltage and frequency and can ultimately trigger wide-area blackouts. Since conventional synchronous generation is being phased out, alternate sources must be included to provide support through ancillary services in future power networks. In a completely decarbonized system, they must also take the lead in ensuring stability and security by participating in blackout defense and network restoration. Offshore wind power plants are deemed suitable candidates due to their capability of providing large amounts of power with fast startup times and advanced control functionalities. However, a change in control philosophy to grid forming is required to enable a more active participation from the next-generation wind turbines. Such changes also have the potential to minimize dependence on auxiliary diesel gensets for a greener carbon footprint. This chapter aims to give insight into the forthcoming challenges and highlight potential solutions to make wind farms more self-reliant resulting in wind energy as cornerstone of the future electricity supply.
The effects of wetting and drying, and marine salt crystallization on calcarenite rocks used as building material in historic monuments

Abstract The results of a study of the effect of marine salt crystallization on the physical and mechanical properties of Plio-Pleistocene calcarenites cropping out in southern Italy are presented here. Owing to their workability, aesthetic appeal and availability, the calcarenites have been widely used as building stones in many historic monuments. Samples of medium-grained packstones and fine-grained packstones-wackestones were prepared for the salt crystallization test defined by EN 12370, using sea water instead of a 14% solution of Na2SO4 · 10H2O. To determine the effect of imbibition alone on the performance of the calcarenites, the same procedure was followed with distilled water without soluble salts. Microfabric analysis, evaluation of index parameters and grain-size distribution were carried out as well. Particular attention was given to pore-size distribution by mercury intrusion porosimetry (MIP), loss of weight and uniaxial compressive strength determined before and after the tests, and after every five cycles of complete immersion in sea water and distilled water. The results suggest that detailed information on fabric and pore network are indispensable to predicting the weatherability of rocks. Crystallization tests that involve the complete immersion of the samples in a saline solution are not effective for an understanding of the real importance of salt damage on soft and porous calcarenites owing to a significant incidence of imbibition in accelerating deterioration rates and in influencing patterns and intensity of weathering.
Yperia Krini spring (central Greece): inferences on climatic changes from its 2000 years of history

Abstract The development of past civilizations and the foundation of towns have always been strictly linked to the availability of water. In this paper, we analyse more than 2000 years of evolution of Yperia Krini spring in Thessaly (Greece), by investigating possible variations in terms of water discharge. In particular, the integrated analysis of geological, hydrological, hydrogeological and historical data relative to the spring, called by Sophocles a ‘gift of God and source of life’, allowed us to understand the role played by both climatic variations and anthropogenic activities on the behaviour and the characteristics of the local underground water resources within the Thessalian plain.
The TU Delft Online Learning Experience: From Theory to Practice

Last year, when we presented the OLE at the 2015 EDEN Conference in Barcelona, we were still at an early stage of its development, collecting fundamental background to support it and feedback from online learning experts. Although we only had a collection of ideas translated into 8 principles, it was clear that the model needed to be flexible in order to accommodate many educational scenarios that coexist among TU Delft’s Faculties, but with a clear and useful purpose to help improve the quality of our online education (Jorge, Dopper & van Valkenburg, 2015). This paper describes how the OLE is applied in practice.The main goal of the OLE is to improve the quality of our online education by setting course design and development principles to support course teams. At the same time, the OLE can be used as a tool to promote reflection before the course starts to set expectations, and in the end to evaluate and plan improvements for the next run. In the next sections we’ll describe the OLE in both ways – as course design principles (guidelines) and as a tool (the radar graph).
Preconditioning for block matrices with square blocks

Dravins, I. 2023. Preconditioning for block matrices with square blocks. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 2246. 69 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-513-1732-8. Linear systems of equations appear in one way or another in almost every scientific and engineering problem. They are so ubiquitous that, in addition to solving linear problems, also non-linear problems are typically reduced to a sequence of linear ones. The field of numerical solution methods for linear systems is rich, but we can broadly classify the methods into two classes: direct solvers and iterative solvers. The availability of modern large-scale computational resources motivates the development and the use of well parallelizable efficient solvers with a limited memory footprint. For many problems, these properties can be achieved by the employment of iterative solution methods combined with preconditioning techniques. This work focuses on the design of preconditioners for block-matrices with square blocks. This form of matrices occurs in many applications, encountered for instance when numerically solving partial differential equations, ordinary differential equations and others. The work in this thesis can broadly be divided into two types of problems, one being optimal control problems within the PDE-constrained optimization framework, and the other being fully implicit Runge-Kutta time-stepping schemes. These necessitate the solution of large and sparse linear systems, for which we employ iterative solution methods. Principal attention is given to Krylov subspace methods. In order to obtain a solution within practical time and memory usage, such methods generally necessitate the use of preconditioners in order to be efficient. The main topic of the thesis is thus the design of preconditioners, although the entire solution procedure is explored.
Global atmospheric sulfur budget under volcanically quiescent conditions: Aerosol‐chemistry‐climate model predictions and validation

The global atmospheric sulfur budget and its emission dependence have been investigated using the coupled aerosol‐chemistry‐climate model SOCOL‐AER. The aerosol module comprises gaseous and aqueous sulfur chemistry and comprehensive microphysics. The particle distribution is resolved by 40 size bins spanning radii from 0.39 nm to 3.2 μm, including size‐dependent particle composition. Aerosol radiative properties required by the climate model are calculated online from the aerosol module. The model successfully reproduces main features of stratospheric aerosols under nonvolcanic conditions, including aerosol extinctions compared to Stratospheric Aerosol and Gas Experiment II (SAGE II) and Halogen Occultation Experiment, and size distributions compared to in situ measurements. The calculated stratospheric aerosol burden is 109 Gg of sulfur, matching the SAGE II‐based estimate (112 Gg). In terms of fluxes through the tropopause, the stratospheric aerosol layer is due to about 43% primary tropospheric aerosol, 28% SO2, 23% carbonyl sulfide (OCS), 4% H2S, and 2% dimethyl sulfide (DMS). Turning off emissions of the short‐lived species SO2, H2S, and DMS shows that OCS alone still establishes about 56% of the original stratospheric aerosol burden. Further sensitivity simulations reveal that anticipated increases in anthropogenic SO2 emissions in China and India have a larger influence on stratospheric aerosols than the same increase in Western Europe or the U.S., due to deep convection in the western Pacific region. However, even a doubling of Chinese and Indian emissions is predicted to increase the stratospheric background aerosol burden only by 9%. In contrast, small to moderate volcanic eruptions, such as that of Nabro in 2011, may easily double the stratospheric aerosol loading.
Late Quaternary evolution of the Rotoaira Basin, northern Tongariro ring plain, New Zealand

Abstract The last 100 000 yr record of volcaniclastic sedimentation in the Rotoaira Basin reflects the critical role played by tectonic and eruptive activity that led to: (1) the catastrophic emplacement of Te Whaiau Formation (60–55 ka); (2) major episodes of effusive activity (c. 30 ka and c. 15 ka); and (3) syn‐ and post‐eruptive lahar aggradation on the shores of Lake Rotoaira. Stratigraphic unconformities, fluvial and aeolian reworking, and subsequent volcanogenic sedimentation indicate that climate change driven periods of erosion contributed significantly to the evolution of the landscape during the late Quaternary. Waters that accumulated in a newly expanded graben formed Lake Rotoaira. An attempt to core through the sediments on the lake's floor revealed a >6.5 m thick mantling of Taupo ignimbrite, restricting chronostratigraphic sampling to the last 1.85 ka. Lake Rotoaira pollen profiles record: (1) the destruction of the indigenous forest by the Taupo ignimbrite eruption; (2) the following period of vegetation recovery (c. 300 yr); and (3) periods of human occupation of the lakeshores (bracken spores and Pinus pollen) in the younger sediments. Coarse sand generated by the 1995–96 tephra‐producing Ruapehu eruptions also contributed to the recent lake sedimentation.
Fission Track Ages of Tephras from Daisen and Sambe Volcanoes and Their Volcanological Implications

大山火山起源の7層準の降下軽石堆積物と1層準のブロックアンドアッシュフロー堆積物,および三瓶火山起源の1層準の軽石流堆積物とその直上の降下軽石堆積物について,フィッショントラック年代測定を行った. 得られた年代値は一部を除いて,テフラ層序,阿蘇4火山灰(Aso-4)や大山倉吉軽石(DKP)の報告されている年代,ローム堆積速度による編年,および報告された大山火山の溶岩のカリウム－アルゴン(K-Ar)年代や層序と整合的である. 大山周辺のローム層は,最も古い330kaを示すcpmより下位のローム層から,姶良Tn火山灰(AT)の上位のローム層まで,およそ35万年間に堆積したことが明らかになった. 三瓶火山起源の三瓶木次軽石(SK)噴火にともなう粕渕火砕流(K2)とSKに対比される木次降下軽石(K3)の年代はおよそ100kaであることが明らかになった. したがって,三瓶火山の活動期間はおよそ10万年間である. この編年に基づくと,大山火山はおよそ35～10万年間に少なくとも13回の,最近10万年間では少なくとも7回のプリニー式噴火を行っている. 三瓶火山は10万年間に5回のプリニー式噴火を行っている.
The Cheslatta Lake suite: Miocene mafic, alkaline magmatism in central British Columbia

New mapping, mineralogical, and geochemical studies help characterize late Tertiary primitive, alkaline, sodic basanite, alkali olivine basalt, transitional basalt, and diabase in the Nechako River, Whitesail Lake, and McLeod Lake map areas of central British Columbia and distinguish the Miocene Cheslatta Lake suite. The suite encompasses scattered erosional remnants of topographically distinct, columnar-jointed, olivine-phyric basalt and diabase volcanic necks, dykes, and associated lava flows north of the Anahim volcanic belt and west of the Pinchi Fault. Volcanic centres at Alasla Mountain and at Cutoff Creek, near Cheslatta Lake, are proposed as type areas. Olivine, plagioclase, and pyroxene phenocrysts, megacrysts, and (or) xenocrysts; common ultramafic xenoliths; and rare but significant plutonic and metamorphic xenoliths are characteristic. Basanite, transitional basalt, and alkali olivine basalt groundmass contain plagioclase, clinopyroxene, Fe-Ti oxides, feldspathoid, olivine, and apatite. The Ch.
Comparison of kriging and inverse-distance methods for mapping soil parameters

Variable-rate technology may provide a means of increasing fertilizer use efficiency by matching applications to specific conditions at a given field location. Effective implementation of this technology depends on accurately characterizing the spatial variability of soil parameters used to define the application rate. Kriging and inversedistance-squared are two commonly used techniques for characterizing this spatial variability and interpolating between sampled points. To assess the accuracy of these techniques, data sets obtained from grid sampling two field research sites were used in a prediction-validation comparison of ordinary kriging and inverse-distance methods using powers p = 1, 2, and 4. The accuracy of the inverse-distance methods tended to increase with the power of distance for data sets with a coefficient of variation less than about 25% (typical of soil organic matter). However, for data sets with greater variation (such as soil NO 3 - ), inverse-distance prediction methods using high distance powers (2 or 4) can give very inaccurate predictions. The accuracy of predictions from kriging was generally unaffected by the coefficient of variation, and was relatively high for all of the sampling configurations considered in this study. These tendencies were also observed using 48- and 72-m subsamples, although the use of wider sampling spacings greatly reduced the information in the maps constructed by each method. Careful thought should be given to the choice of sample spacing and interpolation method to be used before data are collected. Summary statistics, and the coefficient of variation in particular, are simple measures that can give an indication of the relative accuracy of the inverse-distance and kriging mapping approaches.
Tritium–helium 3 dating under complex conditions in hydraulically stressed areas of a buried‐valley aquifer

The 3H‐3He dating method is applied in a buried‐valley aquifer near Dayton, Ohio. The study area is large, not all sampling locations lie along well‐defined flow paths, and existing wells with variable screen lengths and diameters are used. Reliable use of the method at this site requires addressing several complications: (1) The flow system is disturbed because of high pumping rates and induced infiltration; (2) tritium contamination is present in several areas of the aquifer; and (3) radiogenic helium concentrations are elevated in a significant number of the wells. The 3H‐3He ages are examined for self‐consistency by comparing the reconstructed tritium evolution to the annual weighted tritium measured in precipitation; deviations result from dispersion, tritium contamination, and mixing. 3H‐3He ages are next examined for consistency with chlorofluorocarbon ages; the agreement is poor because of degradation of CFCs. Finally, the 3H‐3He ages are examined for consistency with the current understanding of local hydrologic processes; the ages are generally supported by hydrogeologic data and the results of groundwater flow modeling coupled with particle‐tracking analyses.
Solar cycle evolution of the structure of magnetic clouds in the inner heliosphere

Nearly ten years of continuous magnetic field observations by the Pioneer Venus spacecraft allows us to study the correlation between the structure of magnetic clouds in the inner heliosphere and the phase of the solar cycle. Fifty‐six magnetic clouds have been identified in the PVO data at . 7AU during 1979–1988. As this period spans nearly two solar maxima and one solar minimum we can study the evolution of the structure of these magnetic clouds through varying solar activity and under various orientations of the coronal streamer belt. Until shortly after the 1979 solar maximum the majority of clouds had an initially southward magnetic field which turned northward as the cloud was traversed, while in the period leading up to the 1988 solar maximum the majority had a northward field that turned southward. In the declining phase of solar activity magnetic clouds continued to occur, but only a minority can be classified as having south‐to‐north and north‐to‐south rotations. The majority of these clouds occurred with the field remaining entirely north or south relative to the solar equator. These results confirm observations using Helios and ISEE data indicating that the structure of magnetic clouds varies in response to changes in the magnetic structure of the source region. By interpreting these observations to imply that the leading magnetic field in magnetic clouds is controlled by the polarity of the sun's global field and that the inclination of the coronal streamer belt controls the axis of symmetry of the clouds, we can predict preferred magnetic cloud structure and orientation during varying phases of the solar cycle. The helicity of the observations does not seem to be ordered by the solar cycle.
Cooling history of the NW Himalaya, Pakistan

Fission-track and 40Ar/39Ar cooling ages indicate that the late-Tertiary cooling history of the Himalayan ranges of northern Pakistan is largely a function of uplift and erosion. Interpretation of cooling ages which range from under 0.5 Ma to over 80 Ma suggests that during the late Tertiary, long-term uplift rates at least doubled, from under 0.2 mm/yr to in some cases well over 0.5 mm/yr. Uplift rates show strong and systematic regional variations as well which reflect the greater uplift of eastern and northern regions. The association of very rapid uplift and erosion with the Nanga Parbat-Haramosh Massif can be explained by a locally vigorous collision of India with Eurasia near a promontory of Indian crust. The resultant rapid uplift of the Nanga Parbat-Haramosh Massif reactivated the Main Mantle Thrust melange zone with a reversed sense of motion. Discontinuities in the coolingage distribution along the Main Mantle Thrust in the southern Swat-Hazara region may be the result of the thermal effects of overthrusting.
A fission track transect across Nares Strait (Canada–Greenland): further evidence that the Wegener Fault is a myth

Many workers continue to model Nares Strait between Greenland and Ellesmere Island, Canada, as a plate boundary and locus of major Cenozoic compression and strike-slip, marked by the postulated Wegener (transform) Fault. This, despite continuity of Precambrian–Paleozoic provinces across the seaway including an undeformed Neoproterozoic mafic dyke swarm that crosses at a high angle. As a test of the speculative plate kinematic modelling, apatite fission track (AFT) dating was undertaken along a transect across the Paleoproterozoic shield of Smith Sound, at the south end of Nares Strait, running from sea level to ca. 600 m elevation and as much as 70 km inland on both sides. The shield is overlain by three sedimentary basins separated by major hiatuses. The AFT ages fall into two groups: 282 ± 34 and 650 ± 51 Ma. They indicate maximum depth was >4 km in the lower Paleozoic from both coasts to 50 km inland, and at >50 km inland temperatures were below the annealing interval throughout Phanerozoic time. Durin.
A Data Reconciliation Based Approach to Accuracy Enhancement of Operational Data in Power Plants

Accuracy of operational data of a power plant is essential for power plant performance monitoring and fault diagnosis. However, due to inevitable occurrence of systematic and measurement errors in the course of obtaining operational data, these errors can only be reduced to a certain level but never be eliminated. In this work, we propose a data reconciliation based approach to reduce the errors of operational data thus enhance the accuracy of the data. The reconciled data can then be used in performance monitoring and fault diagnosis systems to improve their performances. The proposed method is based on more efficient use of redundant data and a first-principle mathematical model of a power plant. Then an optimization process is performed where the weighted least square form of aggregated differences between measured data and their estimated values are minimized. To illustrate the capability of the proposed method, we provide a case study of data reconciliation for feedwater heater heat balance analysis in a 660 MW coal- fired power plant in China. Results show that uncertainty of four key parameters, namely feed water mass flow rate, condensate mass flow rate, deaerator pressure and outlet temperature, can be reduced by 24 %, 30 %, 5 % and 65 %, whilst the uncertainty of other parameters are also reduced to various extent. Moreover, the results also indicate that the proposed approach is effective over a wide range of measured data quality, where quality of some data could be much worse than others and the estimated measurement uncertainties of operational data may not be accurate.
Surface ozone and precursor gases at Gadanki (13.5°N, 79.2°E), a tropical rural site in India

[1] Ozone, nitrogen oxides (NO′x) (this includes NO, NO2 and some of their compounds converted by molybdenum converter; see section 2.2 for details), CO, and CH4 have been measured during the period 1993–1996 at Gadanki (13.5°N, 79.2°E), a rural site in the tropical Indian region. Observations show daytime photochemical ozone production that is initiated by the photooxidation of the precursor gases, with maximum noontime annual average O3 mixing ratios of only 34 ± 13 ppbv. Ozone levels were highest during the winter/spring period and lowest during summer, which differs from observations at sites in other regions. The rate of increase in O3 is greatest around 0900 hours local time, whereas the magnitude of the maximum rate of decrease during the evening is considerably smaller. This feature distinguishes the urban and rural sites since the magnitudes of the rates during morning and evening are more similar at urban sites. At Gadanki, annual averages of oxides of nitrogen (NO′x), CO, and CH4 are observed to be 2.1 ± 1.8 ppbv, 237 ± 64 ppbv, and 1.70 ± 0.11 ppmv, respectively. However, a poor correlation between ozone and NO′x was found, indicating that NO′x levels at this site are not controlled by fresh combustion or emissions and could be due to transport from the nearby major cities. Ozone production efficiency and estimated photochemical ozone production were also found to be lower at this site.
The Krafla Geothermal Field, Iceland: 4. History match and prediction of individual well performance

A detailed distributed parameter model, in which all wells are represented individually, is reported for the Krafla geothermal system. The model is based on a synthesis of geological, geophysical, geochemical, and reservoir engineering data from the field. Numerical simulations achieve an approximate match for production rates and flowing enthalpies for 10 wells during the period 1976–1982. Predictions of future field performance on a well-by-well basis are presented for alternative field development plans, including additional production wells and reinjection of waste fluids.
The Role of a Man-made Headland in Generating Patches in Coastal Waters of Ise Bay, Japan

Patches of saline water were detected near a tip of a reclaimed land (a man-made headland) in the coastal waters of Ise Bay, Japan, from CTD casts. In addition, acoustic Doppler current profiler (ADCP) observations indicated that the reclaimed land generated local eddies. A hydraulic model and a numerical model provided evidence that the patches were formed by vortices shed at the headland in reversing tidal currents.