Data assimilation for hydraulic state estimation of a development project

International audienceAssurer la sûreté hydraulique sur les aménagements du Rhône est la priorité pour la Compagnie Nationale du Rhône. Cela signifie qu'il est indispensable de respecter les consignes d'exploitation sur les aménagements. Pour la régulation automatique des aménagements, le calcul de la commande prédictive s'appuie sur les mesures en cote en certains points caractéristiques ainsi que sur les débits aux ouvrages. De ce fait, lors de pannes de capteurs ou bien lors de forts phénomènes transitoires (tels que des arrêts ou démarrages de turbines), la régulation est perturbée. Suite à la présente étude, la solution proposée pour corriger les observations et mettre à jour les lignes d'eau intervenant dans le calcul des commandes, est la mise en place d'une méthode d'assimilation de données de type filtre de Kalman. Cette méthode est optimale dans le sens où elle assure la minimisation de l'erreur d'estimation. Mais cela n'est pas suffisant pour certaines applications industrielles. C'est pourquoi les notions de détectabilité et de convergence ont été approfondies. Cette étude a permis de déterminer des conditions suffisantes qui assurent une erreur de l'estimation convergente vers une moyenne nulle. Pour tester la mise en place d'une telle méthode, celle-ci a été implémentée sur l'outil de test industriel appelé " plateforme de simulation ". Des exemples de scénarios habituellement difficiles pour les régulations automatiques, telles que la perte de capteur et l'arrêt brutal d'une turbine sont présentés. Ils permettent de démontrer l'apport de la solution proposée. / Ensure the safety of development projects of the Rhône is the priority of the Compagnie Nationale du Rhône. That means it is essential to respect the water levels at some set points along the river. To regulate its development projects, the computation of the predictive control is based on measurements at the characteristic points as well as flows at the hydraulic facilities. Thus, when failures of sensors occur or during strong transients (such as stopping or starting the turbines), the regulation process can be disturbed. Following this study, the new solution suggested to detect sensor defaults, to correct the observations and to update the water profiles involved in the calculation of control actions, is based on a data assimilation method (Kalman Filter). This method is optimal because it ensures minimizing the estimation error. But this property is not sufficient for our industrial application. This is why the notions of detectability and convergence have been studied into detail. This study has identified sufficient conditions that ensure the error of the estimate to converge towards a nil average. In order to test and validate such a method, it has been implemented into the industrial test tool called "simulation platform." Examples of usually difficult scenarios simulating a loss of sensor and an unexpected stopping of a turbine are presented in this document. It allows demonstrating the benefits of the presented solution

Present and future of surface-enhanced Raman scattering

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article

On-farm food loss in northern and central California: Results of field survey measurementsAuthor links open overlay panel

Prevailing estimates of food loss at the farm level are sparse and often reliant upon grower surveys. A more comprehensive review of food loss at the farm level using field surveys is required to gain an adequate understanding of the depth of this issue. This paper details the results of 123 in-field surveys and 18 in-depth interviews of 20 different, hand-harvested field crops performed largely on midsize to large conventional farms in northern and central California. We also provide estimates of the percentage of fields that go unharvested, commonly known as walk-by fields. The results show that food loss is highly variable and largely dependent upon the crop, variety, market price, labor costs, grower practices, buyer specifications, and environmental conditions. On average, we found 11,299 kg/ha of food loss at the farm level, which equates to 31.3% of the marketed yield. When walk-by losses are included, this figure rises to 33.7%. Our paper also demonstrates that grower estimates are typically very unreliable for estimating on-farm food losses. Actual, measured edible food loss exceeded growers’ estimates by a median value of 157%. Strategies to utilize this lost produce could play a significant role in reducing the impact of agriculture on the environment and providing food for the rapidly growing population

Microscopic origins of the ferromagnetic exchange coupling in oxoverdazyl-based Cu(II) complex

The exchange channels governing the experimentally reported coupling constant Jexpt=6 cm−1 value in the verdazyl-ligand based Cu II complex Cu hfac 2 imvdz are inspected using wave function-based difference dedicated configuration interaction calculations. The interaction between the two spin 1/2 holders is summed up in a unique coupling constant J. Nevertheless, by gradually increasing the level of calculation, different mechanisms of interaction are turned on step by step. In the present system, the calculated exchange interaction then appears alternatively ferromagnetic/ antiferromagnetic/ferromagnetic. Our analysis demonstrates the tremendously importance of some specific exchange mechanisms. It is actually shown that both parts of the imvdz ligand simultaneously influence the ferromagnetic behavior which ultimately reaches Jcalc=6.3 cm−1, in very good agreement with the experimental value. In accordance with the alternation of J, it is shown that the nature of the magnetic behavior results from competing channels. First, an antiferromagnetic contribution can be essentially attributed to single excitations involving the network localized on the verdazyl part. In contrast, the ligand-to-metal charge transfer LMCT involving the imidazole moiety affords a ferromagnetic contribution. The distinct nature / of the mechanisms is responsible for the net ferromagnetic behavior. The intuitively innocent part of the verdazyl-based ligands is deeply reconsidered and opens new routes into the rational design of magnetic object

Reluctant gangsters revisited: the evolution of gangs from postcodes to profits

The aim of the current study was to understand how gangs have changed in the past 10 years since Pitts’ (2008) study in the London Borough of Waltham Forest. The study undertook interviews with 21 practitioners working on gang-related issues and 10 young people affected by gangs or formerly embedded in them. Two focus groups involving 37 participants from key agencies then explored the preliminary findings and contributed to a conceptualization of a new operating model of gangs. The study found that local gangs had evolved into more organized and profit-oriented entities than a decade earlier. The new operating model rejected visible signs of gang membership as ‘bad for business’ because they attracted unwanted attention from law enforcement agencies. Faced with a saturated drugs market in London, gangs moved out to capture drugs markets in smaller UK towns in ‘county lines’ activities. This more business-oriented ethos has changed the meaning of both territory and violence. While gang members in the original study described an emotional connection with their postcode, territory is increasingly regarded as a marketplace to be protected. Similarly, violence has moved from an expressive means of reinforcing gang identity to being increasingly used as an instrumental means of protecting business interests. The current study offers a rare opportunity to gain a picture of gangs at two time periods and contributes to work on the contested nature of UK gangs and renewed interest in gang evolution. These findings have important implications for local authorities and criminal justice agencies who need to address the profit motive of gang activity directly

Grit ingestion and size-related consumption of tubers by Graylag Geese

In herbivorous birds the processing rate of food is constrained by gizzard capacity. To enhance digestive processes, many species ingest grit to grind the food. Grit ingestion, however, may further limit the capacity of file gizzard. Graylag Geese (Anser anser) wintering in SW Spain fed mainly on Alkali Bulrush (Scirpus maritimus) tubers, showing a preference for small tubers. This preference may be due to a faster disintegration of small tubers than larger ones inside the gizzard. As larger tubers are likely coarser than smaller tubers, more grit would be necessary to process larger tubers. However, the ingestion of more grit to grind large tubers would be at the expense of ingesting additional tubers because of gizzard capacity limitations. Under these circumstances, there may be an inverse relationship between tuber size and amount of grit ingested to optimize food ingestion. Indeed, we found such a relationship. Grit facilitated the disintegration of tubers. This suggests that relying on some amount of grit to facilitate the grinding of food should outweigh the loss of gizzard capacity to the amount of food ingested.Peer Reviewe

Orbital dichotomy of Fermi liquid properties in Sr2_2RuO4_4 revealed by Raman spectroscopy

We report a polarization-resolved Raman spectroscopy study of the orbital dependence of the quasiparticles properties in the prototypical multi-band Fermi liquid Sr\textsubscript{2}RuO\textsubscript{4}. We show that the quasiparticle scattering rate displays $\omega^{2}$ dependence as expected for a Fermi liquid. Besides, we observe a clear polarization-dependence in the energy and temperature dependence of the quasiparticle scattering rate and mass, with the $d_{xz/yz}$ orbital derived quasiparticles showing significantly more robust Fermi liquid properties than the $d_{xy}$ orbital derived ones. The observed orbital dichotomy of the quasiparticles is consistent with the picture of Sr\textsubscript{2}RuO\textsubscript{4} as a Hund's metal. Our study establishes Raman scattering as a powerful probe of Fermi liquid properties in correlated metals.Comment: 9 pages, 4 figures, Supplementary Materials available at publisher sit

Fetal central nervous system anomalies: When should we offer exome sequencing?

OBJECTIVE: To investigate the detection of pathogenic variants using exome sequencing in an international cohort of fetuses with central nervous system (CNS) anomalies. METHODS: We reviewed trio exome sequencing (ES) results for two previously reported unselected cohorts (Prenatal Assessment of Genomes and Exomes (PAGE) and CUIMC) to identify fetuses with CNS anomalies with unremarkable karyotypes and chromosomal microarrays. Variants were classified according to ACMG guidelines and association of pathogenic variants with specific types of CNS anomalies explored. RESULTS: ES was performed in 268 pregnancies with a CNS anomaly identified using prenatal ultrasound . Of those with an isolated, single, CNS anomaly, 7/97 (7.2%) had a likely pathogenic/pathogenic (LP/P) variant. This includes 3/23 (13%) fetuses with isolated mild ventriculomegaly and 3/10 (30%) fetuses with isolated agenesis of the corpus callosum. Where there were multiple anomalies within the CNS, 12/63 (19%) had LP/P variants. Of the 108 cases with CNS and other organ system anomalies, 18 (16.7%) had LP/P findings. CONCLUSION: ES is an important tool in the prenatal evaluation of fetuses with any CNS anomaly. The rate of LP/P variants tends to be highest in fetuses with multiple CNS anomalies and multisystem anomalies, however, ES may also be of benefit for isolated CNS anomalies