Optimal Control of the Thermistor Problem in Three Spatial Dimensions

This paper is concerned with the state-constrained optimal control of the three-dimensional thermistor problem, a fully quasilinear coupled system of a parabolic and elliptic PDE with mixed boundary conditions. This system models the heating of a conducting material by means of direct current. Local existence, uniqueness and continuity for the state system are derived by employing maximal parabolic regularity in the fundamental theorem of Pr\"uss. Global solutions are addressed, which includes analysis of the linearized state system via maximal parabolic regularity, and existence of optimal controls is shown if the temperature gradient is under control. The adjoint system involving measures is investigated using a duality argument. These results allow to derive first-order necessary conditions for the optimal control problem in form of a qualified optimality system. The theoretical findings are illustrated by numerical results

Necessary Optimality Conditions for a Dead Oil Isotherm Optimal Control Problem

We study a system of nonlinear partial differential equations resulting from the traditional modelling of oil engineering within the framework of the mechanics of a continuous medium. Recent results on the problem provide existence, uniqueness and regularity of the optimal solution. Here we obtain the first necessary optimality conditions.Comment: 9 page

Aspek Ekologi Ikan Kancera (Tor Soro) Kuningan Dan Pematangan Gonad Melalui Implantasi Hormon Gonadotropin (HCG)

Ecological Aspect and Gonadal Maturation of Tor soro by HCG peletted Implantation. Theexperiment was conducted to determine optimal dosage of Gnrh-a hormon at gonadal maturationof mahseer from Kuningan (Tor soro). The fish was reared in concrete tanks (60m2). Thehormon was used for implantation is HCG (pregnyl). The different dosage of hormon are 250Iu/Kg-1 ; 500 Iu/Kg-1 ; 750 Iu/Kg-1 . The result of this reaserch showed that egg development isMei-Juni (average of egg diameter is 1,4 mm) and Januari (average of egg diameter is 1,35 mm),Other month, the egg diameter was not develop or atresia. Treatment with 500 Iu/Kg-1 dossageshowed the best effect on oosit diameter was at 21 day and 63 day from first oosit diameter of0,9 mm to 1,4 mm

Commissioning of the Liquid Nitrogen Thermo-Siphon System for NASA-JSC Chamber-A

NASA's Space Environment Simulation Laboratory's (SESL) Chamber A, located at the Johnson Space Center in Houston Texas has recently implemented major enhancements of its cryogenic and vacuum systems. The new liquid nitrogen (LN2) thermo-siphon system was successfully commissioned in August of 2012. Chamber A, which has 20 K helium cryo-panels (or shrouds ) which are shielded by 80 K nitrogen shrouds, is capable of simulating a deep space environment necessary to perform ground testing of NASA s James Webb Space Telescope (JWST). Chamber A s previous system used forced flow LN2 cooling with centrifugal pumps, requiring 200,000 liters of LN2 to cool-down and consuming 180,000 liters per day of LN2 in steady operation. The LN2 system did not have the reliability required to meet the long duration test of the JWST, and the cost estimate provided in the initial approach to NASA-JSC by the sub-contractor for refurbishment of the system to meet the reliability goals was prohibitive. At NASA-JSC's request, the JLab Cryogenics Group provided alternative options in 2007, including a thermo-siphon, or natural flow system. This system, eliminated the need for pumps and used one tenth of the original control valves, relief valves, and burst disks. After the thermo-siphon approach was selected, JLab provided technical assistance in the process design, mechanical design, component specification development and commissioning oversight, while the installation and commissioning operations of the system was overseen by the Jacobs Technology/ESC group at JSC. The preliminary commissioning data indicate lower shroud temperatures, 70,000 liters to cool-down and less than 90,000 liters per day consumed in steady operation. All of the performance capabilities have exceeded the design goals. This paper will outline the comparison between the original system and the predicted results of the selected design option, and the commissioning results of thermo-siphon system

Perturbation Theory for Metastable States of the Dirac Equation with Quadratic Vector Interaction

The spectral problem of the Dirac equation in an external quadratic vector potential is considered using the methods of the perturbation theory. The problem is singular and the perturbation series is asymptotic, so that the methods for dealing with divergent series must be used. Among these, the Distributional Borel Sum appears to be the most well suited tool to give answers and to describe the spectral properties of the system. A detailed investigation is made in one and in three space dimensions with a central potential. We present numerical results for the Dirac equation in one space dimension: these are obtained by determining the perturbation expansion and using the Pad\'e approximants for calculating the distributional Borel transform. A complete agreement is found with previous non-perturbative results obtained by the numerical solution of the singular boundary value problem and the determination of the density of the states from the continuous spectrum.Comment: 10 pages, 1 figur

Long-term changes in seagrass and benthos at Banc d’Arguin, Mauritania, the premier intertidal system along the East Atlantic Flyway

The benthic communities of soft-sediment intertidal ecosystems trophically underpin the migration of birds and fish. Within the East Atlantic Flyway, along the coast of West-Africa, the intertidal mudflats of Banc d’Arguin, Mauritania, host over 2 million migratory waterbirds. Despite the protected status of the Banc d’Arguin, geographical remoteness and seemingly benign human exploitation, we show that large changes have taken place in the intertidal benthic macrofauna across an interval of 28 years. We compared the results of two comparable and spatially comprehensive large-scale benthic surveys in 1986 and 2014. Over this time, the benthos changed from a diverse community to one dominated by a few species of bivalve, with a loss of polychaete worms. The change was associated with a twofold increase in the seagrass cover. Our results suggest that the intertidal habitats of Banc d’Arguin have altered markedly over the last three decades and the estimated benthic secondary production has decreased by a factor of four. These shifts in community structure and production may have contributed to declines in some benthivorous migratory shorebirds

Gyroless Spin-Stabilization Controller and Deorbiting Algorithm for CubeSats

CubeSats are becoming increasingly popular in the scientific community. While they provide a whole new range of opportunities for space exploration, they also come with their own challenges. One of the main concerns is the negative impact which they can have in the space debris problem. Commonly lacking from attitude determination and propulsion capabilities, it has been difficult to provide CubeSats with means for active deorbiting. While electric propulsion technology has been emerging for its application in CubeSats, little or no literature is available on methods to enable it to be used for deorbiting purposes, especially within the tight constraints faced by these nanosatellites. We present a new and simple algorithm for CubeSat deorbiting, which proposes the use of novel electric propulsion technology with minimum sensing and actuation capabilities. The algorithm is divided into two stages: a spin-stabilization control; and a deorbiting-phase detection. The spin-stabilization control is inspired by the B-dot controller. It does not require gyroscopes, but only requires magnetometers and magnetorquers as sensors and actuators, respectively. The deorbiting-phase detection is activated once the satellite is spin-stabilized. The algorithm can be easily implementable as it does not require any attitude information other than the orbital information, e.g., from the Global Positioning System receiver, which could be easily installed in CubeSats. The effectiveness of each part of the algorithms is validated through numerical simulations. The proposed algorithms outperform the existing approaches such as deorbiting sails, inflatable structures, and electrodynamic tethers in terms of deorbiting times. Stability and robustness analysis are also provided. The proposed algorithm is ready to be implemented with minimal effort and provides a robust solution to the space junk mitigation efforts

Base-specific mutational intolerance near splice sites clarifies the role of nonessential splice nucleotides

Variation in RNA splicing (i.e., alternative splicing) plays an important role in many diseases. Variants near 5' and 3' splice sites often affect splicing, but the effects of these variants on splicing and disease have not been fully characterized beyond the two "essential" splice nucleotides flanking each exon. Here we provide quantitative measurements of tolerance to mutational disruptions by position and reference allele-alternative allele combinations. We show that certain reference alleles are particularly sensitive to mutations, regardless of the alternative alleles into which they are mutated. Using public RNA-seq data, we demonstrate that individuals carrying such variants have significantly lower levels of the correctly spliced transcript, compared to individuals without them, and confirm that these specific substitutions are highly enriched for known Mendelian mutations. Our results propose a more refined definition of the "splice region" and offer a new way to prioritize and provide functional interpretation of variants identified in diagnostic sequencing and association studies.Peer reviewe

Mathematical Properties of a New Levin-Type Sequence Transformation Introduced by \v{C}\'{\i}\v{z}ek, Zamastil, and Sk\'{a}la. I. Algebraic Theory

\v{C}\'{\i}\v{z}ek, Zamastil, and Sk\'{a}la [J. Math. Phys. \textbf{44}, 962 - 968 (2003)] introduced in connection with the summation of the divergent perturbation expansion of the hydrogen atom in an external magnetic field a new sequence transformation which uses as input data not only the elements of a sequence $\{s_n \}_{n=0}^{\infty}$ of partial sums, but also explicit estimates $\{\omega_n \}_{n=0}^{\infty}$ for the truncation errors. The explicit incorporation of the information contained in the truncation error estimates makes this and related transformations potentially much more powerful than for instance Pad\'{e} approximants. Special cases of the new transformation are sequence transformations introduced by Levin [Int. J. Comput. Math. B \textbf{3}, 371 - 388 (1973)] and Weniger [Comput. Phys. Rep. \textbf{10}, 189 - 371 (1989), Sections 7 -9; Numer. Algor. \textbf{3}, 477 - 486 (1992)] and also a variant of Richardson extrapolation [Phil. Trans. Roy. Soc. London A \textbf{226}, 299 - 349 (1927)]. The algebraic theory of these transformations - explicit expressions, recurrence formulas, explicit expressions in the case of special remainder estimates, and asymptotic order estimates satisfied by rational approximants to power series - is formulated in terms of hitherto unknown mathematical properties of the new transformation introduced by \v{C}\'{\i}\v{z}ek, Zamastil, and Sk\'{a}la. This leads to a considerable formal simplification and unification.Comment: 41 + ii pages, LaTeX2e, 0 figures. Submitted to Journal of Mathematical Physic

Industrial fishing near West African Marine Protected Areas and its potential effects on mobile marine predators

Marine Protected Areas (MPAs) are increasingly implemented to facilitate the conservation of marine biodiversity and key-habitats. However, these areas are often less effective to conserve mobile marine species like elasmobranchs (i.e. sharks and rays). Industrial fishing near MPA borders possibly impacts vulnerable species utilizing these protected areas. Hence, we aimed to study spatiotemporal patterns of industrial fisheries near MPAs, in relation to the bycatch of elasmobranchs. Specifically, we analyzed the spatiotemporal fishing effort within the West African region, mapped fishing effort in the direct vicinity of the Parc National du Banc d’Arguin (Mauritania) and the Bijagós Archipelago (Guinea Bissau) and compared the seasonal overlap between elasmobranch bycatch and fishing effort near these MPAs. We combined Automatic Identification System data and local fisheries observer data, and determined fishing effort for each gear type and compared this with bycatch of elasmobranchs. We found that industrial fishing effort was dominated by trawling, drifting longlines and fixed gear types. Although no industrial fishing was observed within both MPAs, 72% and 78% of the buffer zones surrounding the MPAs were fished for the Banc d’Arguin and Bijagós respectively. Within the Banc d’Arguin buffer zone, trawling and drifting longlines dominated, with longlines mainly being deployed in fall. In the Bijagós buffer zone, trawling and fixed gears were most prevalent. Fisheries observer data for Mauritania showed that elasmobranch catches increased during the most recent sampling years (2016 to 2018). Elasmobranch catches within the waters of Guinea Bissau peaked in 2016 and decreased in the following two years. Seasonal patterns in elasmobranch bycatch within the waters of both countries are likely caused by increased catches of migratory species. Catches of rays peaked in May and June for Mauritania, and in October for Guinea Bissau. Shark catches were highest in February and July in Mauritanian waters, and in May and October in the waters of Guinea Bissau. Our study indicates that industrial fisheries near the border of ecologically important MPAs may have potentially major implications for ecosystem functioning by the removal of (migratory) predatory species