In this thesis the Tobii eye-tracker 4L was used to investigate how well eye-tracking solutions such as a confirmation-click and dwell-time algorithm compares to the standard mouse input device when performing selection tasks in a map environment. In order to distinguish the different complexity one could face, two user cases are proposed. Scenario one includes non clustered objects. Scenario two include clustered occluded objects. A user study with nine different participants where conducted in order to compare the execution times and find out how error prone the different methods were. Each test participant performed eight different tests, three in the non-clustered scenario and five in the clustered scenario. In two of the tests in the clustered scenario test participants were aided with zooming through a zoom algorithm. The methods was evaluated by calculating the average execution times and errors along with the corresponding standard deviations. In order to grasp the users experience a subjective cognitive load score was calculated with the help of a questionnaire. The eye-tracker methods was found to be competitive in comparison to mouse interaction in the more simple non-clustered case. However, in a more complex scenario such as the clustered case the mouse interaction had the lowest average completion time and cognitive load score. A different type of selection behaviour was discovered among the test participants in the clustered scenario due to the difference in precision between the eye-tracker and mouse interaction. Finally interesting areas to consider in the future is presented and discussed. / I denna avhandling användes en Tobii eye-tracker 4L för att undersöka hur väl eye-tracking metoder så som en bekräftelseklick och dwell-time algoritm jämför sig med standard mus interaktion vid objekt selektion i en kartmiljö. För att urskilja variationen i komplexitet man kan möta föreslås två olika användarfall. Scenario ett inkluderar objekt som är distinktivt separerade och därav ej grupperade. Scenario två inkluderar grupperade samt ockluderade objekt. En användarstudie med nio olika deltagare genomfördes för att jämföra exekveringstiderna och ta reda på hur felbenägna de olika metoderna var. Varje testdeltagare utförde åtta olika tester, tre i det icke-grupperade scenariot och fem i det grupperade scenariot. I två av testerna i det grupperade scenariot fick deltagarna hjälp med att zooma genom en zoomalgoritm. Metoderna utvärderades genom att beräkna de genomsnittliga exekveringstiderna samt antal fel tillsammans med motsvarande standardavvikelser. För att förstå hur användarna upplevde de olika metoderna togs en subjektiv kognitiv belastningspoäng fram genom ett frågeformulär. Eye-tracker metoderna var konkurrenskraftiga i jämförelse med musinteraktion i det enklare fallet där objekt ej var grupperade. I ett mer komplext scenario, såsom i det grupperade fallet, hade dock musinteraktionen den lägsta genomsnittliga exekveringstiden och kognitiva belastningspoängen. En annan typ av selektions beteende upptäcktes bland testdeltagarna i det grupperade scenariot på grund av skillnaden i precision mellan eye-trackern och musinteraktionen. Slutligen presenteras och diskuteras intressanta områden att överväga vid framtida arbeten.

Object tracking can be done in numerous ways, where the goal is to track a target through all frames in a sequence. The ground truth bounding box is used to initialize the object tracking algorithm. Object tracking can be carried out on infrared imagery suitable for military applications to execute tracking even without illumination. Objects, such as aircraft, can deploy countermeasures to impede tracking. The countermeasures most often mainly impact one wavelength band. Therefore, using two different wavelength bands for object tracking can counteract the impact of the countermeasures. The dataset was created from simulations. The countermeasures applied to the dataset are flares and Directional Infrared Countermeasures (DIRCMs). Different object tracking algorithms exist, and many are based on discriminative correlation filters (DCF). The thesis investigated the DCF-based trackers STRCF and ECO on the created dataset. The STRCF and the ECO trackers were analyzed using one and two wavelength bands. The following features were investigated for both trackers: grayscale, Histogram of Oriented Gradients (HOG), and pre-trained deep features. The results indicated that the STRCF and the ECO trackers using two wavelength bands instead of one improved performance on sequences with countermeasures. The use of HOG, deep features, or a combination of both improved the performance of the STRCF tracker using two wavelength bands. Likewise, the performance of the ECO tracker using two wavelength bands was improved by the use of deep features. However, the negative aspect of using two wavelength bands and introducing more features is that it resulted in a lower frame rate.

MScEng / Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Accurate dimensional measurement devices are critical for international industrial competitiveness for South Africa. An overview of all the necessary components of a laser tracking system using a multilateration technique for very accurate dimensional metrology is presented. A prototype laser tracker station was built to further investigate this type of system. The prototype successfully tracks a target within a volume of at least 200 200 200 mm3, approximately 300 mm away from the tracker. This system includes the mechanical design of a prototype tracker station, electronic implementation of ampli cation and motor control circuits, a tracking control algorithm, microcontroller programming and interfacing, as well as a user interface. Kinematic modelling along with Monte Carlo analyses nd the main error source of such a tracker as the beam steering mechanism gimbal axes misalignment. Multilateration is also motivated by the results found by the analysis. Furthermore, an initial sequential multilateration algorithm is developed and tested. The results of these tests are promising and motivate the use of multilateration over a single beam laser tracking system. / AFRIKAANSE OPSOMMING: Dit is van kritieke belang dat Suid-Afrika akkurate dimensionele metingstoestelle ontwikkel vir internasionale industriële medinging. 'n Oorsig van al die nodige komponente vir 'n Laser-Volgsisteem, wat slegs van multilaterasie gebruik maak om baie akkurate drie dimensionele metings te kan neem, word in hierdie projek voorgestel. 'n Prototipe Laser-Volgsisteem-stasie word gebou om so 'n sisteem verder te ondersoek. Die prototipe slaag wel daarin om 'n teiken, binne 'n volume van 200 200 200 mm3 op 'n afstand van omtrent 300 mm te volg. Die sisteem sluit die meganiese ontwerp van die sodanige stasie, elektroniese seinversterking, motorbeheer, 'n volgingsbeheer algoritme, mikroverwerker programeering en intergrasie, asook 'n gebruikerskoppelvlak program in. Kinematiese modelering, tesame met Monte Carlo simulasies, toon aan dat die hoof oorsaak van metingsfoute by so 'n stasie by die rotasie-asse van die laserstraal-stuurmeganisme, wat nie haaks is nie, lê. Die multilaterasie metode word ook verder ondersteun deur dié modelering. 'n Algoritme wat sekwensiële multilateratsie toepas word boonop ontwikkel en getoets. Die resultate van die toetse dui daarop dat die algoritme funksioneer en dat daar voordele daarin kan wees om so 'n metode in plaas van 'n Enkelstraal-Volgsisteem te gebruik.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Current ground-based tracking systems at the DoD test and training ranges require transmission of a variety of signals from rotating platform to fixed control and process center. Implementation of commercial off the shelf (COTS) solution for transmitting high-speed, multiple-channel data signals over a rotational platform prompt the development of an advanced electro-optic hybrid rotating-to-fixed information transmission technology. Based on current demand, an Air Force-sponsored Small Business Innovative Research (SBIR) contract has been awarded to Physical Optics Corporation (POC) to modify existing tracking mounts with a unique electro-optic hybrid rotary joint (EOHRJ). The EOHRJ under current development is expected to provide the following features: 1) include a specially designed electrical slip-ring, which is able to accommodate hundreds of transmission channels, including electrical power, control, feedback, and low-speed data signals; 2) include an optical fiber slip-ring which, by incorporating with electrical time division mulitplexing (TDM) and optical wavelength division multiplexing (WDM) technologies, is able to provide multiple channel, high data rate (over gigabits per second), and bi-directional signal transmission; and 3) is designed to be reliable for harsh environmental operation, adaptive to stringent size requirement, and accommodating to existing electrical and mechanical interfaces. Besides the military use, other possible commercial applications include on board monitoring of satellite spinners, surveillance systems, instrumentation and multi spectral vision systems, emergency/medical instruments, remote sensing, and robotics.

Um das Entdeckungspotential des Large Hadron Colliders auszunutzen, wird er beginnend 2024 zum High Luminosity Large Hadron Collider ausgebaut. Neue Detektorherausforderungen entstehen durch die höhere instantane Luminosität und den höheren Teilchenfluss. Der neue ATLAS Inner Tracker wird den aktuellen Spurdetektor ersetzen, um mit diesen Herausforderungen umzugehen. Es gibt viele Pixeldetektortechnologien zur Teilchenspurerkennung, jedoch muss ihre Eignung für den ATLAS Inner Tracker untersucht werden. Aktive Hochspannungs-CMOS-Sensoren, die in industriellen Prozessen produziert werden, bieten eine schnelle Auslese und Strahlenhärte. In dieser Arbeit wird der HV2FEI4v2-Sensor, der kapazitiv mit dem ATLAS-FE-I4-Auslesechip gekoppelt ist, dahingehend charakterisiert, ob er für eine Verwendung in einer der äußeren Lagen des ATLAS Inner Tracker geeignet ist. Schlüsselgrößen des Prototypens, wie die Treffereffizienz und die Subpixelentschlüsselung, werden untersucht. Der frühe HV2FEI4v2-Prototyp zeigt vielversprechende Ergebnisse, die als Ausgangspunkt für weitere Entwicklungen dienen. Aktive CMOS-Sensoren stellen einen möglichen Kandidaten für einen kosteneffizienten Detektor für den High Luminosity Large Hadron Collider.

Work title: The response of the visual system when driving a car in real conditions and in a simulator during a parallel motor task. Aims: To implement a laboratory measurement in a driving simulator and in real conditions during a parallel motor task. To track the response of the visual system during the task and to determine potential differences in the response of the visual system and in the speed in the simulator and in the real car environment. Methods: The laboratory measurement was realized in a driving simulator OCTAVIA II. The measurement in real conditions was realized in Škoda Octavia as well. The eye-tracking method was used to track the drivers` eyes. Results: In the simulator the more experienced driver managed to do the parallel motor task within a shorter period of time than the less experienced driver, lower frequency of looks at the radio during the tasks with the more experienced driver was not proved. There was not an evidence of more balanced speed during the drive with the more experienced driver in the simulator. On the average the driver spent shorter time doing the tasks in the real environment than in the simulator and the total number of looks at the radio was lower. The speed of the drive in the real environment was lower than the speed in the simulator. Key words:...

A neotenia é um importante processo biológico-evolutivo que conserva traços fenotípicos do jovem no indivíduo adulto. A neotenia modifica a velocidade típica da ontogênese das características morfológicas compartilhadas pelos ancestrais. Essas mudanças podem representar oportunidades de mudanças fenotípicas dramáticas com poucas alterações genéticas, possibilitando alterações de estados especializados. O etólogo Konrad Lorenz reconheceu características neotênicas em humanos e algumas espécies de mamíferos na fórmula estrutural do corpo (principalmente da face) típica de infantes. Essa fórmula corpórea foi batizada por Lorenz de Kindchenschema. Os humanos típicos respondem quando observam traços infantis ativando uma resposta chamada de Efeito Kindchenschema (EK). Neste efeito verifica-se uma diminuição da agressividade, estimulação do cuidado parental e engajamento social. São raros os trabalhos de escaneamento do olhar em portadores de disfunções do neurodesenvolvimento, como a Síndrome de Williams (SW) e o Transtorno do Espectro Autista (TEA). O presente trabalho é o primeiro na literatura a investigar o escaneamento do olhar em portadores de SW e TEA usando estímulos faciais neotênicos de humanos e animais. Na presente investigação foram estudados 21 portadores de SW e 25 portadores de TEA, o grupo controle (GC) contou com 33 participantes. Encontramos uma correspondência entre os resultados declarados do estímulo preferido e o tempo de fixação. Os resultados mostraram que todos os participantes fixaram mais a região dos olhos de humanos e animais, sendo que o GC fixou mais tempo do que os portadores de SW e TEA. Foi possível separar usando o tempo de fixação nos olhos e HeatMaps os três grupos investigados. É viável a produção de um exame clínico auxiliar rápido e não-invasivo para indivíduos com suspeita de uma disfunção do neurodesenvolvimento. Talvez a região do nariz e boca sejam menos importantes e as orelhas mais importantes do que pensávamos nos estímulos neotênicos. Os estímulos mais neotênicos de infantes humanos e animais produziram um padrão semelhantes do tempo de fixação nos três grupos estudados. Esses resultados demonstram que portadores de SW e TEA respondem positivamente a estímulos faciais neotênicos. Sugerimos que as novas investigações na área incorporem também como variáveis faciais as orelhas, cor do cabelo e olhos, e simetria facial / Neoteny is an important biological-evolutionary process that retains phenotypic traits of the young in the adult individual of a species. Neoteny modifies the typical ontogeny velocity of the morphological characteristics shared with the ancestors. These changes may represent opportunities for dramatic phenotype modifications with few genetic changes, allowing for alterations in specialized states. The ethologist Konrad Lorenz has recognized neotenic characteristics in humans and some species of mammals in the structural formula of the body (mainly of the face) typical of infants. This body formula was named by Lorenz Kindchenschema. Typical humans respond when they observe infant traits by activating a response called the Kindchenschema Effect (KE). In this effect, there is a decrease in aggressiveness, stimulation of parental care and social engagement. There is a paucity of eye scanning in individuals with neurodevelopmental disorders such as Williams Syndrome (WS) and Autistic Spectrum Disorder (ASD). The present work is the first in the literature to investigate the eye scanning in WS and ASD patients using neotenic facial stimuli of humans and animals. In the present investigation, 21 WS and 25 ASD participants were studied. The control group (CG) had 33 participants. We found a correspondence between the stated results of the preferred stimulus and the fixation time. The results showed that all the participants fixed more the region of the eyes of humans and animals, and the CG fixed more time than the WS and ASD participants. It was possible to distinguish, using the fixation time in the eyes and Heat Maps, the three groups. The production of a rapid and non-invasive auxiliary clinical examination is feasible for individuals suspected in presenting a neurodevelopmental dysfunction. Perhaps the nose and mouth areas are less important, and the ears are more important than previously considered with respect. The more neotenic stimuli of human and animal infants produced a similar pattern of fixation time in the three groups studied. This may represent a greater adaptive value than we thought of those with WS and ASD. We suggest that the new investigations can also incorporate facial variables as ears, hair color and eyes, and facial symmetry

A matriz energética brasileira atualmente está concentrada na geração de energia hidrelétrica. Mas, devido aos últimos acontecimentos de escassez de recursos hídricos, faz-se necessário diversificar a matriz energética por meio do investimento em energias alternativas. O Brasil ainda possui muitas pessoas na área rural sem abastecimento de energia elétrica, fato que limita a implantação de técnicas agrícolas como a irrigação. Nesse contexto, a energia solar fotovoltaica (FV) é uma alternativa para diversificar a matriz energética brasileira e ampliar o uso de sistemas de irrigação. Foram instalados dois módulos FV, um estático e outro com um sistema de rastreamento solar manual de três passos, na área experimental do Departamento de Engenharia de Biossistemas - ESALQ/USP (22° 42\' 30\'\'S, 47° 38\' 00\'\'W, altitude de 546 metros). Para cada módulo FV, estático e móvel, foram acoplados sistemas de bombeamento de água para um sistema simulado de irrigação. O objetivo foi avaliar o incremento de energia FV gerada, tempo de bombeamento, volume bombeado e área irrigada; com o uso do sistema rastreador. A partir dos dados encontrados, verificou-se que o sistema rastreador solar manual de três passos apresentou maior eficiência na captação de energia (8 - 19% dia-1), quando comparado com geradores fixos; o que refletiu no incremento significativo do tempo de bombeamento (40 - 160 min dia-1), no volume bombeado (884 - 3479 litros dia-1) e na área irrigada (196 - 773 m² dia-1 para uma lâmina de irrigação de 4,5 mm). Com isso, o rastreador se mostrou uma alternativa técnica viável para melhorar a captação de energia solar e aumentar a área irrigada com um mesmo tamanho de área de gerador FV. Em relação ao investimento, o sistema rastreador custou apenas 0,2% do custo total da instalação FV, e proporcionou a redução do tempo de retorno do investimento em 2 anos e 5 meses comparado ao módulo FV estático. / The current Brazilian Energetic Matrix is concentrated in the generation of hydroelectric energy. But, due the latest water resources scarcity, it is necessary to diversify the energetic matrix by investing in alternatives energies. Brazil still have a plenty of people living in rural areas without supply of electric energy, this fact limits the implantation of agriculture techniques like irrigation. In this sense, the photovoltaic solar energy (PV) is an alternative to diversify the Brazilian Energetic Matrix and expand the use of irrigation systems. It were installed two PV modules, one static and another with solar three steps manual tracking system, Biosystems Engineering Department - ESALQ/USP (22° 42\' 30\'\'S, 47°38\' 00\'\'W, at 546 meters altitude). For each PV module, static and moving, it was coupled water pumping systems for simulated irrigation systems. The goal was evaluate the gain of the PV energy generated; pumping time; pumping volume and irrigated area; using the tracking system. From obtained data, it was observed that the solar three steps manual tracking system shows more efficiency in the energy harvesting (8 - 19% day-1), compared to static generator; which resulted in significant gain of pumping time (40 - 160 min day-1), pumping volume (884 - 3479 liters day-1) and irrigates area (196 - 773 m² day-1 for a irrigation depth equal 4.5 mm). Therewith, the tracking system shows a viable alternative technique to improve solar energy harvesting and increase the irrigated area with same area of PV generator. In relation to investment of the tracking system, it cost only 0.2 % of the total cost of PV installation and provided the reduction in the return on investment time of 2 years and 5 month compared to static PV module.

A neotenia é um importante processo biológico-evolutivo que conserva traços fenotípicos do jovem no indivíduo adulto. A neotenia modifica a velocidade típica da ontogênese das características morfológicas compartilhadas pelos ancestrais. Essas mudanças podem representar oportunidades de mudanças fenotípicas dramáticas com poucas alterações genéticas, possibilitando alterações de estados especializados. O etólogo Konrad Lorenz reconheceu características neotênicas em humanos e algumas espécies de mamíferos na fórmula estrutural do corpo (principalmente da face) típica de infantes. Essa fórmula corpórea foi batizada por Lorenz de Kindchenschema. Os humanos típicos respondem quando observam traços infantis ativando uma resposta chamada de Efeito Kindchenschema (EK). Neste efeito verifica-se uma diminuição da agressividade, estimulação do cuidado parental e engajamento social. São raros os trabalhos de escaneamento do olhar em portadores de disfunções do neurodesenvolvimento, como a Síndrome de Williams (SW) e o Transtorno do Espectro Autista (TEA). O presente trabalho é o primeiro na literatura a investigar o escaneamento do olhar em portadores de SW e TEA usando estímulos faciais neotênicos de humanos e animais. Na presente investigação foram estudados 21 portadores de SW e 25 portadores de TEA, o grupo controle (GC) contou com 33 participantes. Encontramos uma correspondência entre os resultados declarados do estímulo preferido e o tempo de fixação. Os resultados mostraram que todos os participantes fixaram mais a região dos olhos de humanos e animais, sendo que o GC fixou mais tempo do que os portadores de SW e TEA. Foi possível separar usando o tempo de fixação nos olhos e HeatMaps os três grupos investigados. É viável a produção de um exame clínico auxiliar rápido e não-invasivo para indivíduos com suspeita de uma disfunção do neurodesenvolvimento. Talvez a região do nariz e boca sejam menos importantes e as orelhas mais importantes do que pensávamos nos estímulos neotênicos. Os estímulos mais neotênicos de infantes humanos e animais produziram um padrão semelhantes do tempo de fixação nos três grupos estudados. Esses resultados demonstram que portadores de SW e TEA respondem positivamente a estímulos faciais neotênicos. Sugerimos que as novas investigações na área incorporem também como variáveis faciais as orelhas, cor do cabelo e olhos, e simetria facial / Neoteny is an important biological-evolutionary process that retains phenotypic traits of the young in the adult individual of a species. Neoteny modifies the typical ontogeny velocity of the morphological characteristics shared with the ancestors. These changes may represent opportunities for dramatic phenotype modifications with few genetic changes, allowing for alterations in specialized states. The ethologist Konrad Lorenz has recognized neotenic characteristics in humans and some species of mammals in the structural formula of the body (mainly of the face) typical of infants. This body formula was named by Lorenz Kindchenschema. Typical humans respond when they observe infant traits by activating a response called the Kindchenschema Effect (KE). In this effect, there is a decrease in aggressiveness, stimulation of parental care and social engagement. There is a paucity of eye scanning in individuals with neurodevelopmental disorders such as Williams Syndrome (WS) and Autistic Spectrum Disorder (ASD). The present work is the first in the literature to investigate the eye scanning in WS and ASD patients using neotenic facial stimuli of humans and animals. In the present investigation, 21 WS and 25 ASD participants were studied. The control group (CG) had 33 participants. We found a correspondence between the stated results of the preferred stimulus and the fixation time. The results showed that all the participants fixed more the region of the eyes of humans and animals, and the CG fixed more time than the WS and ASD participants. It was possible to distinguish, using the fixation time in the eyes and Heat Maps, the three groups. The production of a rapid and non-invasive auxiliary clinical examination is feasible for individuals suspected in presenting a neurodevelopmental dysfunction. Perhaps the nose and mouth areas are less important, and the ears are more important than previously considered with respect. The more neotenic stimuli of human and animal infants produced a similar pattern of fixation time in the three groups studied. This may represent a greater adaptive value than we thought of those with WS and ASD. We suggest that the new investigations can also incorporate facial variables as ears, hair color and eyes, and facial symmetry

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-02-10T11:07:35Z No. of bitstreams: 1 Jair Carlos Muller_.pdf: 2333529 bytes, checksum: 36c56be5b98f22351456fbe4e419d28f (MD5) / Made available in DSpace on 2017-02-10T11:07:35Z (GMT). No. of bitstreams: 1 Jair Carlos Muller_.pdf: 2333529 bytes, checksum: 36c56be5b98f22351456fbe4e419d28f (MD5) Previous issue date: 2016-10-04 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / Este trabalho apresenta um estudo geométrico de um refletor Fresnel linear para a produção de energia térmica com uso de um rastreador solar para orientação dos espelhos. A realização deste trabalho teve como base o estudo do sistema de coordenadas empregado para o cálculo da inclinação dos espelhos em função da posição do Sol em um determinado instante. O método utilizado considera que a radiação direta proveniente do Sol atinja o centro do espelho, cuja inclinação a cada instante permite a reflexão dessa radiação para o centro do absorvedor, situado a uma dada altura em relação ao plano contendo o eixo dos espelhos. Através do estudo da inclinação dos espelhos, foram analisadas as influencias causadas pela distância entre espelhos, altura do receptor, largura dos espelhos e o número de espelhos. Com estes parâmetros analisados, implementou-se uma simulação em MATLAB que forneceu valores de potência refletida no plano de entrada do concentrador secundário, valores de perdas por sombreamento, bloqueio, desfocagem e posição angular de cada fileira de espelho. Tendo estes dados como base foi construído um rastreador solar controlado por um micro controlador Arduino, que permite orientar as fileiras de espelhos com um único motor e eixo de acoplamento. O programa no micro controlador verifica data e hora como dados iniciais, depois as coordenadas geográficas de latitude 29º 45’ 17,979” S e longitude 51º 9’ 1,019” W do local. Assim, foi possível comprovar, através de imagens refletidas pelos espelhos no receptor secundário, que os parâmetros de posição angular estão corretos e que a concentração dos raios solares no absorvedor do concentrador secundário tem precisão adequada, fornecendo ao sistema confiabilidade para sua utilização. / This paper presents a geometric study of a linear Fresnel reflector for the production of thermal energy with use of a solar tracker for orientation of mirrors. This work was based on the study of the coordinate system used for the calculation of the slope of the mirrors as function of the sun’s position at a given time. The method considers that the solar direct radiation reaches the center of the mirror, whose slope at each instant allows the reflection of this radiation to the center of the absorber located at a given height from the plane containing the axis of the mirrors. Through the study of slope of mirrors, were analyzed the influences caused by the distance between mirrors, the height of receiver, width of the mirrors and the number of mirrors. With these parameters, it was implemented a simulation in MATLAB which provided power values reflected in the secondary concentrator inlet plane, values of losses by shading, blocking, by defocus and the angular position of each row of mirror. Having these data as base was built a controlled solar tracker by an Arduino micro controller, which allows directing the rows of mirrors with a single engine and coupling shaft. The program in micro controller checks the date and time as initial data, then the geographical coordinates of latitude 29° 45 ' 17.979 "S and longitude 51° 9 ' 1.019" W the local. Thus, it was possible to prove, through images reflected by mirrors on the secondary receiver, that the angular position parameters are correct and that the concentration of sunrays in the absorber secondary hub has adequate accuracy, providing the system reliability for its use.