2,366 research outputs found
3x3 Multibeam Network for a Triangular Array of Three Radiating Elements
A multibeam antenna study based on Butler network will be undertaken in this document. These antenna designs combines phase shift systems with multibeam networks to optimize multiple channel systems. The system will work at 1.7 GHz with circular polarization. Specifically, result simulations and measurements of 3 element triangular subarray will be shown. A 45 element triangular array will be formed by the subarrays. Using triangular subarrays, side lobes and crossing points are reduced
Building a Chemical Ontology using Methontology and the Ontology Design Environment
METHONTOLOGY PROVIDES GUIDELINES FOR SPECIFYING ONTOLOGIES AT THE KNOWLEDGE LEVEL, AS A SPECIFICATION OF A CONCEPTUALIZATION. ODE ENABLES ONTOLOGY CONSTRUCTION, COVERING THE ENTIRE LIFE CYCLE AND AUTOMATICALLY IMPLEMENTING ONTOLOGIE
Planktonic Chlorophyceae from the lower Ebro River (Spain)
On samples obtained in 4 seasonal periods between April 1999 and February 2000 from the last 18 km of Ebro River (Spain) some interesting planktonic coccal green algae (Chlorophyceae) were found. This paper offers comments and taxonomical observations
on 60 taxa. Crucigenia smithii (Kirchner) W. et G. S. West, Crucigeniella pulchra (W. et G.S.West) Komárek, Elakatothrix genevensis (Reverdin) Hindák, E. subacuta Koršikov,
Nephrocytium schilleri (Kammerer) Comas, Oocystidium ovale Kor{ikov, Pseudoschroederia antillarum (Komárek) Hegewald et Schnepf, Scenedesmus denticulatus var. fenestratus
(Teiling) Uherkovich, S. pannonicus Hortobágyi, Siderocelis ornata (Fott) Fott, Tetrachlorella alternans (G.M. Smith) Koršikov and Tetrastrum komarekii Hindák were found for the first time in this country. The best represented genus was Scenedesmus, with
16 taxa
The role of passive surveillance and citizen science in plant health
The early detection of plant pests and diseases is vital to the success of any eradication or control programme, but the resources for surveillance are often limited. Plant health authorities can however make use of observations from individuals and stakeholder groups who are monitoring for signs of ill health. Volunteered data is most often discussed in relation to citizen science groups, however these groups are only part of a wider network of professional agents, land-users and owners who can all contribute to significantly increase surveillance efforts through “passive surveillance”. These ad-hoc reports represent chance observations by individuals who may not necessarily be looking for signs of pests and diseases when they are discovered. Passive surveillance contributes vital observations in support of national and international surveillance programs, detecting potentially unknown issues in the wider landscape, beyond points of entry and the plant trade. This review sets out to describe various forms of passive surveillance, identify analytical methods that can be applied to these “messy” unstructured data, and indicate how new programs can be established and maintained. Case studies discuss two tree health projects from Great Britain (TreeAlert and Observatree) to illustrate the challenges and successes of existing passive surveillance programmes. When analysing passive surveillance reports it is important to understand the observers’ probability to detect and report each plant health issue, which will vary depending on how distinctive the symptoms are and the experience of the observer. It is also vital to assess how representative the reports are and whether they occur more frequently in certain locations. Methods are increasingly available to predict species distributions from large datasets, but more work is needed to understand how these apply to rare events such as new introductions. One solution for general surveillance is to develop and maintain a network of tree health volunteers, but this requires a large investment in training, feedback and engagement to maintain motivation. There are already many working examples of passive surveillance programmes and the suite of options to interpret the resulting datasets is growing rapidly
EXPLORING THE ONE LECTURE – ONE TEST LEARNING SYSTEM IN JOURNALISM CLASS SETTING
This paper explores the One-Lecture-One Test teaching and learning system. Unlike the conventional system which gives two or three tests that count score-wise, the One-Lecture-One Test system prescribes that a short test of about 10 to 15 minutes long must be written by the students at the end of each lecture. Each test is formal, which means that it counts towards the continuous assessment which is cumulatively calculated at the end of the semester and forms part of the overall grade and requirements for graduation. In order to determine how effective the new system could be with journalism students of a leading tertiary institution in Nigeria, this work studied it, using five parameters, namely test scores and grades, lecture attendance, interest of students in class, rate of participation of students and the profile of concentration by students. When the results were compared with those obtained from the survey of the conventional system, the efficiency of the new system was significant, as it showed up as a promoter of test-wiseness
Longitudinal study of individual exercises in elite rhythmic gymnastics
[Abstract] The performance evolution in rhythmic gymnastics depends on changes in code of
points. At the beginning of each Olympic cycle the code of points changes and therefore,
the content of the competition exercises, as well. This study aimed to analyze – for
each apparatus – the evolution of number of technical elements and final score over
the last two decades (last 13 world championships), how they have been affected by
changed code of points, and how the final score relates to the number of technical
elements performed. The sample consisted of 416 exercises in five apparatus: ball (96),
rope (40), hoop (96), ribbon (88), and clubs (96). The following variables were gathered:
code of points, apparatus, technical group, total number of elements, final classification,
and final score. Linear mixed-effects models were used to examine the effects on
the number of elements and final score in each apparatus. The number of technical
elements increased in all apparatus, between 7.4 and 20% over a 10-year period. There
were mixed evolutions of final score between the different apparatus, between 6.3 and
14% over a 10-year period. There is small increase in number of elements in hoop and
a small decrease in rope after a code change. There was a small decrease in final score
in championships after a code change in hoop, moderate in clubs and ribbon, and large
in rope. There was a negative relationship between number of elements performed and
final score in clubs. In conclusion, the code change generally effects the final score
negatively, but there were apparatus specific effects of code change on number of
elements and relationship between number of elements and final score
Broadside parallel plate slot antenna without dielectric
A linearly polarized flat antenna with broadside beam radiation is presented in this paper. A rectangular slot array in the upper side of a parallel plate waveguide
form the main antenna structure. In previous works, the authors have presented one and dual tilted-beam antennas [1-2] for the reception of Hispasat or Astra satellite emissions in the 12 GHz band. The problem of the broadside beam antenna is to avoid the grating lobes. The main goal of the work presented here is getting a low cost broadside antenna that does not need a dielectric material inside the parallel plate to solve the grating lobes problem
Diseño y construcción de antena plana de doble polarización basada en ranuras para recepción de TV por satélite
In this paper we design and make a double-polarization plane
slot antenna for Digital Television Satellite reception. The prototype will fulfil the DVB specifications and furthermore it should be simple to construct and cheap. Therefore in the design process and in the implementation process exists a compromise
between the specifications, low costs and simplicity
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