1,688 research outputs found
Fuzzy Inference System for VOLT/VAR control in distribution substations in isolated power systems
This paper presents a fuzzy inference system for voltage/reactive power
control in distribution substations. The purpose is go forward to automation
distribution and its implementation in isolated power systems where control
capabilities are limited and it is common using the same applications as in
continental power systems. This means that lot of functionalities do not apply
and computational burden generates high response times. A fuzzy controller,
with logic guidelines embedded based upon heuristic rules resulting from
operators at dispatch control center past experience, has been designed.
Working as an on-line tool, it has been tested under real conditions and it has
managed the operation during a whole day in a distribution substation. Within
the limits of control capabilities of the system, the controller maintained
successfully an acceptable voltage profile, power factor values over 0,98 and
it has ostensibly improved the performance given by an optimal power flow based
automation system
Performance enhancement of surface codes via recursive MWPM decoding
The minimum weight perfect matching (MWPM) decoder is the standard decoding
strategy for quantum surface codes. However, it suffers a harsh decrease in
performance when subjected to biased or non-identical quantum noise. In this
work, we modify the conventional MWPM decoder so that it considers the biases,
the non-uniformities and the relationship between , and errors of
the constituent qubits of a given surface code. Our modified approach, which we
refer to as the recursive MWPM decoder, obtains an improvement in the
probability threshold under depolarizing noise. We also obtain
significant performance improvements when considering biased noise and
independent non-identically distributed (i.ni.d.) error models derived from
measurements performed on state-of-the-art quantum processors. In fact, when
subjected to i.ni.d. noise, the recursive MWPM decoder yields a performance
improvement of over the conventional MWPM strategy and, in some
cases, it even surpasses the performance obtained over the well-known
depolarizing channel
Decoding algorithms for surface codes
Quantum technologies have the potential to solve computationally hard
problems that are intractable via classical means. Unfortunately, the unstable
nature of quantum information makes it prone to errors. For this reason,
quantum error correction is an invaluable tool to make quantum information
reliable and enable the ultimate goal of fault-tolerant quantum computing.
Surface codes currently stand as the most promising candidates to build error
corrected qubits given their two-dimensional architecture, a requirement of
only local operations, and high tolerance to quantum noise. Decoding algorithms
are an integral component of any error correction scheme, as they are tasked
with producing accurate estimates of the errors that affect quantum
information, so that it can subsequently be corrected. A critical aspect of
decoding algorithms is their speed, since the quantum state will suffer
additional errors with the passage of time. This poses a connundrum-like
tradeoff, where decoding performance is improved at the expense of complexity
and viceversa. In this review, a thorough discussion of state-of-the-art
surface code decoding algorithms is provided. The core operation of these
methods is described along with existing variants that show promise for
improved results. In addition, both the decoding performance, in terms of error
correction capability, and decoding complexity, are compared. A review of the
existing software tools regarding surface code decoding is also provided.Comment: 54 pages, 31 figure
Influencia del polimorfismo -3826 A Æ G en el gen de la UCP1 sobre los componentes del síndrome metabólico
Fundamento. La proteína desacoplante UCP1 se ha relacionado con el desarrollo y/o mantenimiento de la obesidad a través de su implicación en la regulación del balance energético. El papel de esta proteína mitocondrial en humanos es incierto por la escasa presencia del tejido adiposo pardo en el individuo adulto. El polimorfismo -3826 A/G de la UCP1 solo o conjuntamente con la mutación Trp64Arg del receptor adrenérgico β3 se ha asociado con obesidad, diabetes mellitus y enfermedades relacionadas aunque con resultados contradictorios.
Con objeto de conocer la influencia del polimorfismo -3826 A/G de la UCP1 sobre los componentes clásicos del síndrome metabólico en nuestra población, se han estudiado 159 individuos obesos y 154 en normopeso, con un diseño de casos y controles. A todos ellos se les ha determinado IMC, índice cintura/cadera, % de grasa corporal, TA, perfil lipídico, leptina, glucemia e insulinemia basales. Asimismo se les ha analizado la presencia de la mencionada mutación en el gen de la UCP1.
Resultados. Se obtuvieron diferencias significativas en todas las variables estudiadas entre obesos (casos) y normopeso (controles) Dentro del grupo de obesos, el polimorfismo –3826 A/G del gen de la UCP1 (n=53) se asoció con un mayor IMC (p=0,03), mayor % de grasa corporal (p=0,04) y TA más elevada tanto sistólica (p=0,009) como diastólica (p=0,02) No hubo diferencias estadísticamente significativas en ninguno de los demás índices evaluados.
Conclusión. El factor fundamental que influye sobre los componentes del síndrome metabólico es la obesidad. No obstante, el polimorfismo –3826 A/G del gen de la UCP1 se asocia con un mayor grado de obesidad y unas cifras más elevadas de TA
Cycle of Knowledge in the Management of the Supply Chain of Corn for Human Consumption
The objective of this study is to characterize the cycle of knowledge in the supply chain of the industry of corn for human consumption. White corn is cultivated almost exclusively for human consumption and it has a significant value in the food supply in countries whose diet has a high proportion of this variety of corn, such as: Venezuela, México and Colombia in America, and the Republic of South Africa and Sahel countries in Africa. Corn is produced in Venezuela, under rainfed conditions and in a highly mechanized production system. The cycle of knowledge is defined as a progressive spiral in which knowledge is created, stored, transferred, applied and preserved, in order to increase the competitiveness and sustainability of organizations and companies in the food supply chain. This non experimental and crosssectional research is of a descriptive type. It was conducted in Venezuela during the second semester of 2009 in the supply chain of white corn, specifically, at the level of first tier producers (primary sector). The population is constituted by 1,754 producers of corn in the most important producing regions of the country. The representative sample was selected by the stratified sampling technique with proportional allocation: by association of corn producers and according to the grain yield. A questionnaire was designed and conducted according to the structured survey method. Its validity was verified by discriminant tests of items and its reliability through Bartlett's test, variance factorial analysis, Kaiser/Meyer/Olkin and Cronbach Alpha, achieving the last one a value of 0.9276.The production units have an average area of 67.17 ha, with 1.97 permanent workers and 4.06 temporary workers. They obtained a physical productivity of 4,210.45 kg/ha. The Knowledge Index (KI) achieved a value of 69.78% and the Perception Index of the results (PI) was 76.06%. The Pearson correlation among these indices was positive and significant with a value of 0.51. The factorial analysis for principal components with rotated factors allows obtaining four factors from the five dimensions originally considered. These factors are: (1) knowledge creation, (2) knowledge storage, (3) knowledge transfer and application, and (4) preservation of knowledge.The results allow us to conclude that the cycle of knowledge is managed in four stages in an intuitive and predominantly tacit manner which is the reason why those practices related to explicit knowledge become the agents of differentiation. Moreover, the existence of a positive correlation between the Knowledge Index and the Perception Index of the positive results by the producer was also proven
Reproductive and bloom patterns of Pelagia noctiluca in the Strait of Messina, Italy
Investigations on sexual reproduction of jellyfish are essential to understanding mechanisms and patterns
of outbreaks formation. Pelagia noctiluca (Forskål, 1775) (Scyphozoa) is known as the predominant
jellyfish species with direct development in Western and Central Mediterranean Sea. In this paper we
used integrated morphometric, histological, and biochemical approaches to investigate the annual
reproductive biology of P. noctiluca from the Strait of Messina (South Thyrrenian Sea), a key proliferation
area for this species due to favourable temperatures and high productivity. From November 2011 to
September 2012, P. noctiluca sexual reproduction occurred throughout the year, with two seasonal peaks
(autumn, spring) of spawning and embryonic development. Gonads of female P. noctiluca were characterized
by a large amount of mature eggs of small size (diameter < 200 mm) during high food availability,
whereas fewer, larger eggs (diameter > 200 mm) were detected during low availability of prey.
Two morphometric indexes were applied: the Gonad-Somatic Index (GSI, gonadal/somatic tissue dry
weight ratio) and Fecundity Index (FI, n eggs mm2 * gonadal dry weight). The FI showed longer
spawning periods than the GSI, providing a better causal-mechanistic explanation for the year-round
occurrence of P. noctiluca in the Strait of Messina. Protein contents of the gonads changed seasonally,
with the highest concentrations during the pre-spawning periods. We suggest that investigations on
jellyfish sexual reproduction can provide biological information relevant for understanding mechanisms
of jellyfish blooms as well as for the management of coastal zones affected by outbreaks of gelatinous
species
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Effects of Cryogenic Aging on a Rapid Prototyped (RP) Polymer
Little research has been done on the post-processing (aging) of rapid prototyped (RP)
polymers at temperatures below 123K (–238˚F). Test specimens of RP thermosetting resin
(DSM-Somos 8110) were fabricated and cryogenically aged from 10-25 hours. The tensile
strength and impact toughness were measured. This work will study the effect of cryogenic
aging on yield strength of Somos 8110. This paper will also discuss our interpretation of the data
based on fractography.The work was funded by an NSF Grant under Research Experiences for Undergraduates
(REU).Mechanical Engineerin
Multi-qubit time-varying quantum channels for NISQ-era superconducting quantum processors
Recent experimental studies have shown that the relaxation time () and
the dephasing time () of superconducting qubits fluctuate considerably
over time. To appropriately consider this time-varying nature of the and
parameters, a new class of quantum channels, known as Time-Varying
Quantum Channels (TVQCs), has been proposed. In previous works, realizations of
multi-qubit TVQCs have been assumed to be equal for all the qubits of an error
correction block, implying that the random variables that describe the
fluctuations of and are block-to-block uncorrelated, but qubit-wise
perfectly correlated for the same block. Physically, the fluctuations of these
decoherence parameters are explained by the incoherent coupling of the qubits
with unstable near-resonant two-level-systems (TLS), which indicates that such
variations may be local to each of the qubits of the system. In this article,
we perform a correlation analysis of the fluctuations of the relaxation times
of multi-qubit quantum processors ibmq\_quito, ibmq\_belem, ibmq\_lima,
ibmq\_santiago and ibmq\_bogota. Our results show that it is reasonable to
assume that the fluctuations of the relaxation and dephasing times of
superconducting qubits are local to each of the qubits of the system. Based on
these results, we discuss the multi-qubit TVQCs when the fluctuations of the
decoherence parameters for an error correction block are qubit-wise
uncorrelated (as well as from block-to-block), a scenario we have named the
Fast Time-Varying Quantum Channel (FTVQC). Furthermore, we lower bound the
quantum capacity of general FTVQCs based on a quantity we refer to as the
ergodic quantum capacity. Finally, we use numerical simulations to study the
performance of quantum error correction codes (QECC) when they operate over
FTVQCs.Comment: 21 page
AGROTECH09: building agricultural robots with lego mindstorm. A multidisciplinary and multicultural approach
This activity has been designed in the context of an innovation project devoted to the coordination on mathematical, physical, and engineering contents for a transversal path on mechatronics, automated control and information and communication technologies (from now onwards AGROMECATIC) at agricultural engineering studies in the Technical University of Madrid. One of the main tasks has consisted on setting up a new subject, robotics in agriculture (equivalent to 7 ECTS), which is used as a platform to test the abilities of the students to apply various aspects of the knowledge gathered along the previous 4 years on agricultural engineering, with special emphasis on. The students are demanded to build a variety of basic mechanisms into an autonomous vehicle capable of performing user defined general and specific agricultural tasks (such as selective harvest, transport, loading and unloading of product). The robot is programmed using object oriented language (LEJOS, JAVA for LEGO) and has to cover a variety of behaviors: navigation, exploration, and previous defined agricultural tasks. As a mean to test the skills developed by the students and to reinforce the multidisciplinary nature of AGROMECATICS, a European contest: AGROTECH09 has been settled, which is co-organized by BEST (Board of European Students of Technology). The activity will take place between the 11 th and 14 th of May at ETSI Agrónomos and recognizes up to 2 ECTS of individual dedication. 40 students from 16 countries with large variability of backgrounds: computers science, agronomy, engineering, physics, tele-communication will work jointly to solve a challenge which will be public on the 11 th of May with all materials being provided by the organization
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