Hybrid Dynamic Surrogate Modelling for a Once-Through Steam Generator

Hybrid Dynamic Surrogate Modelling for a Once-Through Steam GeneratorFour surrogate modelling techniques are compared in the context of modelling once-through steam generators (OTSGs) for offshore combined cycle gas turbines (GTCCs): Linear and polynomial regression, Gaussian process regression and neural networks for regression. Both fully data-driven models and hybrid models based on residual modelling are explored. We find that speed-ups on the order of 10k are achievable while keeping root mean squared error at less than 1%. Our work demonstrates the feasibility of developing OTSG surrogate models suitable for real-time operational optimization in a digital twin context. This may accelerate the adoption of GTCCs in offshore industry and potentially contribute towards a 25% reduction in emissions from oil & gas platforms.acceptedVersio

Reconstructing early Holocene seasonal bottom-water temperatures in the northern North Sea using stable oxygen isotope records of Arctica islandica shells

The knowledge of seasonal temperature variability in the ocean is essential for understanding climate and its response to forcing factors. Time intervals with highly dynamic climate and increased seasonal forcing such as the early Holocene are of particular interest. Yet, the temporal resolution of most existing climate records is not sufficient to reconstruct temperature seasonality. Here, we present the first seasonally resolved, early Holocene, bottom-water temperature record from the Viking Bank in the northern North Sea. The reconstruction is based on the stable oxygen isotope data (δ18Oshell) of two crossdated, radiocarbon-dated subfossil shells of Arctica islandica (Bivalvia). Oxygen isotope data were combined into a 21-year long record, dated at 9593–9573 (±55) cal yr BP The record indicates an early Holocene seasonal temperature amplitude up to ca. 4.5 °C. To estimate changes in the mean state and seasonality of temperature conditions between the present and early Holocene, the record and temperatures inferred thereof are compared with modern δ18Oshell profiles and instrumental temperature data. The results indicate that the seasonal amplitude of δ18Oshell signal in the subfossil shells reflects sea-level changes. The reconstruction suggests that the long-term average and seasonal variability of temperature were similar to modern times when considering changes in the relative sea level. Our data also confirm that δ18Oshell records are reproducible and track seasonal amplitude of bottom-water temperature variability, thus demonstrate the potential for application in reconstructions of past seasonality. Furthermore, our results show that δ18Oshell records can be used to reconstruct seasonal stratification dynamics. This novel application of sclerochronological data has the potential to be used to validate and constrain paleotidal models.publishedVersio

Effects of reducing dietary content of crude protein and indispensable amino acids on performance and carcass traits of single-phase- and 2-phase-fed growing-finishing pigs

Effects of reducing dietary content of crude protein (CP) and Lys on performance and carcass traits of growing-finishing pigs were studied in 690 crossbred (Swedish Yorkshire dams x Hampshire sires) female and vaccinated entire male pigs with an average initial live weight (LW) of 32.3 kg. The pigs were raised in pens with mixed sexes and were fed restrictedly using 2 different feeding plans, single-phase and 2-phase. Within each feeding plan, 3 CP contents were investigated: 13.5 (low), 14.5 (medium), and 15.5 (high) g standardized ileal digestible(SID) CP/g SID Lys. Each CP comprised 2 Lys contents. For single-phase-fed pigs this implied either 0.76 or0.85 g SID Lys/MJ net energy (NE). For 2-phase-fed pigs, the contents were either 0.89 in phase 1 and 0.71 in phase 2 or 0.98 in phase 1 and 0.79 in phase 2 g SID Lys/MJ NE. In low and high Lys, the expected total consumption of digestible Lys from start to slaughter was calculated to be equal for single-phase- and 2-phase-fedpigs. The change of diet in the 2-phase feeding plan was at an average LW of 60.8 kg and slaughter was performed at 117.3 kg. Irrespective of dietary CP and Lys content, 2-phase-fed pigs had higher daily weight gain(DWG) and better feed conversion in phase 1 than single-phase-fed pigs. In phase 2, single-phase-fed pigs fully compensated, so that overall DWG and feed conversion did not differ between single-phase- and 2-phase-fed pigs(1014 vs. 1013 g/d; 24.5 vs. 24.5 MJ NE/kg DWG). Dietary CP content had no effect on DWG and feed conversion in phase 1. However, pigs grew faster and had better feed conversion in phase 2 (P= 0.002 and P= 0.018, respectively) and during the entire raising period with the high CP content (P= 0.003 and P= 0.006, respectively). For both single-phase- and 2-phase-fed pigs, high dietary Lys content improved DWG and feed conversion in phase 1 compared with the low content (1002 vs. 968 g/d;P= 0.001 and 20.7 vs.21.5 MJ NE/kg DWG;P= 0.004), whereas no difference was observed in phase 2. Overall, Lys content did not affect DWG, while feed conversion was better for pigs fed the high Lys content (P= 0.035). Carcass traits were unaffected by feeding plan, CP, and Lys content. Reducing dietary CP content from high to low diminished the N output by approximately 20%. The conclusions are that growing-finishing pigs had the capacity for compensatory growth and can therefore be single-phase-fed, and that the current recommendations of CP and Lys could be reduced

Heat integration and heat exchanger network design for oxyfuel cement plants

The cement sector needs to reduce its CO2 emissions. An oxyfuel CO2 capture technology allows to considerably reduce the emission. However, heat recovery and energy efficiency measures are essential to make the technology economically feasible. An approach to design heat exchanger networks applied to a 1st generation oxyfuel cement plant is described in this article. The approach consists of two steps: preliminary targeting and heat exchanger network design. For the studied cement plant, the steam Rankine cycle was identified to be superior to organic Rankine cycles. In the ideal case about 10.5 MW of power can be recovered. However, in a cost-efficient simple heat exchanger network recovery of only about 8.7 MW is economically reasonableHeat integration and heat exchanger network design for oxyfuel cement plantsacceptedVersio

How to accurately fast-track sorbent selection for post-combustion CO2 capture? A comparative assessment of data-driven and simplified physical models for screening sorbents

The recent discovery of a multitude of hypothetical materials for CO2 capture applications necessitated the development of reliable computational models to aid the quest for better-performing sorbents. Given the computational challenges associated with existing detailed adsorption process design and optimization frameworks, two types of screening methodologies based on computationally inexpensive models, namely, data-driven and simplified physical models, have been proposed in the literature. This study compares these two screening methodologies for their effectiveness in identifying best-performing sorbents from a set of 369 metal-organic frameworks (MOFs). The results showed that almost 60% of the MOFs in the top 20 best-performing materials ranked by each of these approaches were found to be common. The validation of these results against detailed process simulation and optimization-based screening approach is currently underway. © 2023 Elsevier B.V. Author keywords adsorption; machine learning; metal-organic frameworks; modelling and optimization; post-combustion CO2 captureHow to accurately fast-track sorbent selection for post-combustion CO2 capture? A comparative assessment of data-driven and simplified physical models for screening sorbentsacceptedVersio

Asymmetric introgression reveals the genetic architecture of a plumage trait

Genome-wide variation in introgression rates across hybrid zones offers a powerful opportunity for studying population differentiation. One poorly understood pattern of introgression is the geographic displacement of a trait implicated in lineage divergence from genome-wide population boundaries. While difficult to interpret, this pattern can facilitate the dissection of trait genetic architecture because traits become uncoupled from their ancestral genomic background. We studied an example of trait displacement generated by the introgression of head plumage coloration from personata to alba subspecies of the white wagtail. A previous study of their hybrid zone in Siberia revealed that the geographic transition in this sexual signal that mediates assortative mating was offset from other traits and genetic markers. Here we show that head plumage is associated with two small genetic regions. Despite having a simple genetic architecture, head plumage inheritance is consistent with partial dominance and epistasis, which could contribute to its asymmetric introgression. Hybrid zones are windows into the evolutionary process. Semenov et al. find that the head plumage differences between white wagtail subspecies have a simple genetic basis involving two small genetic regions, in which partially dominant and epistatic interactions help to explain how this sexual signal has become decoupled from other plumage traits

Model predictive control of compact combined cycles in offshore power plants integrating a wind farm

Model predictive control of compact combined cycles in offshore power plants integrating a wind farmCombined cycle gas turbine plants (CCGTs) fulfill an important role in emission reduction of offshore power systems as the bottoming cycle (BC) produces additional power from exhaust heat of the gas turbines (GTs). With increasing integration of wind turbines, CCGTs offshore must be flexible and provide variation management to the offshore energy system across multiple time scales. This work proposes a model predictive controller (MPC) sending setpoints to the CCGT to satisfy demand in the offshore power system under fluctuating wind power. A high-speed surrogate model suitable for optimizing in an MPC is identified. A linear MPC using a quadratic cost function with process constraints is formulated. The model-based control structure is then validated in simulation for satisfying a constant power demand under disturbances introduced by fluctuating wind power.acceptedVersio

Rapid adaptive radiation of Darwin's finches depends on ancestral genetic modules

Recent adaptive radiations are models for investigating mechanisms contributing to the evolution of biodiversity. An unresolved question is the relative importance of new mutations, ancestral variants, and introgressive hybridization for phenotypic evolution and speciation. Here, we address this issue using Darwin's finches and investigate the genomic architecture underlying their phenotypic diversity. Admixture mapping for beak and body size in the small, medium, and large ground finches revealed 28 loci showing strong genetic differentiation. These loci represent ancestral haplotype blocks with origins predating speciation events during the Darwin's finch radiation. Genes expressed in the developing beak are overrepresented in these genomic regions. Ancestral haplotypes constitute genetic modules for selection and act as key determinants of the unusual phenotypic diversity of Darwin's finches. Such ancestral haplotype blocks can be critical for how species adapt to environmental variability and change

Разработка рекламной кампании промышленного предприятия и оценка ее эффективности (на примере ОАО «Коминтерн»)

Spectra of triply charged carbon disulphide have been obtained by measuring, in coincidence, all three electrons ejected in its formation by photoionization. Measurements of the CS23+ ion in coincidence with the three electrons identify the energy range where stable trications are formed. A sharp peak in this energy range is identified as the 2Π ground state at 53.1±0.1 eV, which is the lowest electronic state according to ab initio molecular orbital calculations. Triple ionization by the double Auger effect is provisionally divided, on the basis of the pattern of energy sharing between the two Auger electrons into contributions from direct and cascade Auger processes. The spectra from the direct double Auger effect via S 2p, S 2s, and C 1s hole states contain several resolved features and show selectivity based on the initial charge localization and on the identity of the initial state. Triple ionization spectra from single Auger decay of S 2p -based core-valence states CS22+ show retention of the valence holes in this Auger process. Related ion-electron coincidence measurements give the triple ionization yields and the breakdown patterns in triple photoionization at selected photon energies from 90 eV to above the inner shell edges

Sensory Ataxic Neuropathy in Golden Retriever Dogs Is Caused by a Deletion in the Mitochondrial tRNATyr Gene

Sensory ataxic neuropathy (SAN) is a recently identified neurological disorder in golden retrievers. Pedigree analysis revealed that all affected dogs belong to one maternal lineage, and a statistical analysis showed that the disorder has a mitochondrial origin. A one base pair deletion in the mitochondrial tRNATyr gene was identified at position 5304 in affected dogs after re-sequencing the complete mitochondrial genome of seven individuals. The deletion was not found among dogs representing 18 different breeds or in six wolves, ruling out this as a common polymorphism. The mutation could be traced back to a common ancestor of all affected dogs that lived in the 1970s. We used a quantitative oligonucleotide ligation assay to establish the degree of heteroplasmy in blood and tissue samples from affected dogs and controls. Affected dogs and their first to fourth degree relatives had 0–11% wild-type (wt) sequence, while more distant relatives ranged between 5% and 60% wt sequence and all unrelated golden retrievers had 100% wt sequence. Northern blot analysis showed that tRNATyr had a 10-fold lower steady-state level in affected dogs compared with controls. Four out of five affected dogs showed decreases in mitochondrial ATP production rates and respiratory chain enzyme activities together with morphological alterations in muscle tissue, resembling the changes reported in human mitochondrial pathology. Altogether, these results provide conclusive evidence that the deletion in the mitochondrial tRNATyr gene is the causative mutation for SAN