Linear Model-Based Predictive Control of the LHC 1.8 K Cryogenic Loop

The LHC accelerator will employ 1800 superconducting magnets (for guidance and focusing of the particle beams) in a pressurized superfluid helium bath at 1.9 K. This temperature is a severely constrained control parameter in order to avoid the transition from the superconducting to the normal state. Cryogenic processes are difficult to regulate due to their highly non-linear physical parameters (heat capacity, thermal conductance, etc.) and undesirable peculiarities like non self-regulating process, inverse response and variable dead time. To reduce the requirements on either temperature sensor or cryogenic system performance, various control strategies have been investigated on a reduced-scale LHC prototype built at CERN (String Test). Model Based Predictive Control (MBPC) is a regulation algorithm based on the explicit use of a process model to forecast the plant output over a certain prediction horizon. This predicted controlled variable is used in an on-line optimization procedure that minimizes an appropriate cost function to determine the manipulated variable. One of the main characteristics of the MBPC is that it can easily incorporate process constraints; therefore the regulation band amplitude can be substantially reduced and optimally placed. An MBPC controller has completed a run where performance and robustness has been compared against a standard PI controller (Proportional and Integral)

Acción diferencial de dos formulaciones de azadiractina sobre los estados de desarrollo de Ceratitis Capitata (Wiedemann) (Diptera: Tephritidae)

Pruebas de toxicidad con dos formulados de azadiractina (Align y Neem-e) sobre Ceratitis capitata (Wiedemann) realizadas en laboratorio, mostraron un distinto grado de actividad dependiente del producto y del estado de desarrollo de la mosca tratado. A bajas concentraciones Neem-e no tuvo acción ovicida ni larvicida, mientras que Align inhibió la eclosión del 90% de los huevos tratados a una dosis de 4,2 mg/l y a 1 mg/l no emergieron adultos, cuando las larvas neonatas se criaron en dieta tratada. Por el contrario, Align no tuvo ningún efecto tóxico al ser suministrado en el agua de beber a adultos de la mosca, mientras que Neem-e fue moderamente activo, obteniéndose una mortalidad del 100% para una dosis de 50 mg/

Aging Uncouples Heritability and Expression-QTL in Caenorhabditis elegans

The number and distribution of gene expression QTL (eQTL) represent the genetic architecture of many complex traits, including common human diseases. We previously reported that the heritable eQTL patterns are highly dynamic with age in an N2 × CB4856 recombinant inbred population of the nematode Caenorhabditis elegans. In particular, we showed that the number of eQTL decreased with age. Here, we investigated the reason for this decrease by combining gene expression profiles at three ages in the wild types N2 and CB4856 with the reported expression profiles of the RIL population. We determined heritability and transgression (when gene expression levels in the RILs are more extreme than the parents) and investigated their relation with eQTL changes with age. Transgressive segregation was widespread but depended on physiological age. The percentage of genes with an eQTL increased with a higher heritability in young worms. However, for old worms this percentage hardly increased. Using a single marker approach, we found that almost 20% of genes with heritability >0.9 had an eQTL in developing worms. Surprisingly, only 10% was found in old worms. Using a multimarker approach, this percentage increased to almost 30% for both age groups. Comparison of the single marker to a multiple marker eQTL mapping indicated that heritable regulation of gene expression becomes more polygenic in aging worms due to multiple loci and possible epistatic interactions. We conclude that linkage studies should account for the relation between increased polygenic regulation and diminished effects at older ages

Non-Linear Advanced Control of the LHC Inner Triplet Heat Exchanger Test Unit

The future Large Hadron Collider (LHC) at CERN will include eight interaction region final focus magnet systems, the so-called "Inner Triplet", one on each side of the four beam collision points. The Inner Triplets will be cooled in a static bath of pressurized He II nominally at 1.9 K. This temperature is a control parameter and has very severe constraints in order to avoid the transition from the superconducting to normal resistive state. The main difference in these special zones with respect to a regular LHC cell is higher dynamic heat load unevenly distributed which modifies largely the process characteristics and hence the controller performance. Several control strategies have already been tested at CERN in a pilot plant (LHC String Test) which reproduced a LHC half-cell. In order to validate a common control structure along the whole LHC ring, a Nonlinear Model Predictive Control (NMPC) has been developed and implemented in the Inner Triplet Heat Exchanger Unit (IT-HXTU) at CERN. Automation of the Inner Triplet setup and the advanced control techniques deployed based on the Model Based Predictive Control (MBPC) principle are presented

Applying Advanced Control Techniques for Temperature Regulation of the LHC Superconducting Magnets

The temperature of the superconducting magnets for the future LHC accelerator is a control parameter with strict operating constraints imposed by (a) the maximum temperature at which the magnets can o perate, (b) the cooling capacity of the cryogenic system, (c) the variability of applied heat loads and (d) the accuracy of the instrumentation. A temperature regulation with narrow control band can i n principle be achieved by implementing a Model Predictive Control (MPC)-type controller. For this purpose, and for investigating the behaviour of the cooling system, a simulation program has been dev eloped. A prototype MPC controller has been installed and completed its first run

He II Heat Exchanger Test Unit for the LHC Inner Triplet

The Inner Triplet Heat Exchanger Test Unit (IT-HXTU) is a 30-m long thermal model designed at Fermilab, built in US industry, fully automated and tested at CERN as part of the US LHC program to develop the LHC Interaction Region quadrupole system. The cooling scheme of the IT-HXTU is based on heat exchange between stagnant pressurized He II in the magnet cold mass and saturated He II (two-phase) flowing in a heat exchanger located outside of and parallel to the cold mass. The purposes of this test are, among others, to validate the proposed cooling scheme and to define an optimal control strategy to be implemented in the future LHC accelerator. This paper discusses the results for the heat exchanger test runs and emphasizes the thermal and hydraulic behavior of He II for the inner triplet cooling scheme

Lethal and Sublethal Effects of Methoxyfenozide on the Development, Survival and Reproduction on of the Fall Armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The lethal and sublethal effects of the ecdysone agonist methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith), were investigated by feeding a methoxyfenozide-treated diet to fifth instars until pupation in doses corresponding to the LC10 and LC25 for the compound. Larval mortality reached 8% and 26% in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12% for the LC10 and 60% for the LC25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a significant effect on the timing of larval development. The development period for males and females was about seven days longer than the controls for both concentrations tested. In contrast, the compound affected neither pupae nor adult longevity. Finally, S. frugiperda adults that resulted from fifth instars treated with methoxyfenozide were not affected in their mean cumulative number of eggs laid per female (fecundity), nor percentages of eggs hatched (fertility), or the sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm

Instrumentation, Field Network and Process Automation for the Cryogenic System of the LHC Test String

CERN is now setting up String 2, a full-size prototype of a regular cell of the LHC arc. It is composed of two quadrupole, six dipole magnets, and a separate cryogenic distribution line (QRL) for the supply and recovery of the cryogen. An electrical feed box (DFB), with up to 38 High Temperature Superconducting (HTS) leads, powers the magnets. About 700 sensors and actuators are distributed along four Profibus DP and two Profibus PA field buses. The process automation is handled by two controllers, running 126 Closed Control Loops (CCL). This paper describes the cryogenic control system, associated instrumentation, and their commissioning

Desarrollo de un sistema de Gestión Frutihortícola

La tendencia actual hacia la globalización en todas las áreas de negocios, de los que no escapan los agropecuarios, ha significado un aumento de la competencia, tanto en intensidad como diversidad. En particular, el productor frutihortícola debe disponer de elementos que le permitan comprender los mercados como también contar con metodologías y herramientas con las cuales identificar debilidades y fortalezas de sus sistemas productivos, ir adaptándose a un medio altamente dinámico y dar sentido estratégico a la dirección de la empresa. Se propuso desarrollar un aplicativo que, sin pretender ser un sistema de contabilidad de costos, utiliza a ésta como principal fuente del conocimiento. Es así como se estructuró el sistema de gestión orientado, cuya interactividad surge a partir de las actividades que desarrolla habitualmente el productor en su establecimiento. A partir de allí se disparan una serie de procesos estructurados que concluyen en el registro de la actividad como en un sistema de contabilidad de costos. Se desarrolló un sistema informático basado en tecnología Microsoft Office Access para Windows como gestor de base de datos y entorno de desarrollo Visual Basic for Applications. El sistema aún no se está utilizando a campo, pero se cuenta con grupos de productores dispuestos a probarlo.Sociedad Argentina de Informática e Investigación Operativ

Calidad de agua para riego en invernáculos de la región central de la Provincia de La Pampa

En zona aledaña a la ciudad de Santa Rosa, provincia de La Pampa, ha cobrado importancia el cultivo de hortalizas. El agua utilizada para el riego es extra Ida de perforaciones y eventualmente de alguna laguna. Es por ello que en este trabajo se determina la calidad del agua que se utiliza para el riego y se aportan datos concretos y posibles prácticas de manejo. En este trabajo, desarrollado durante los años 1997 y 1998, se determinaron las características químicas Relación de absorción de Sodio, Carbonato de Sodio Residual y concentración de cationes y aniones, y las características físicas pH, sales totales disueltas y conductividad eléctrica del agua de diferentes pozos, para luego clasificarla siguiendo el criterio del Laboratorio de Salinidad de Riverside (USDA) y de la FAO. El pH del agua de los pozos analizados no presentó ninguna restricción en ningún momento, mientras que de las otras características analizadas siempre se presentó alguna restricción en algún pozo. En los pozos muestreados, en general no se detectaron restos de nitritos ni de amonio, a excepción del pozo N° 8 que presentó un contenido de amonio comprendido en el rango de 0 a 10 partes por millón. En el agua de los pozos N° 1, N° 4, N° 5 Y N° 7 se halló que la concentración de arsénico es superior a la tolerancia admitida por la Organización Mundial de la Salud. Los pozos N° 8 Y N° 10 no presentaron ninguna restricción respecto al total de sales disueltas.Director: Ing. Agr. Nilda B. Reinaudi Cátedra de Química. Facultad de Agronomía. Universidad Nacional de La Pampa.Co-Director: Ing. Agr. Horacio C. Gregoire Cátedra de Horticultura, Facultad de Agronomía. Universidad Nacional de La Pampa