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Adequate illumination of the larynx is needed during laryngoscopy to facilitate tracheal intubation. The International Organization for Standardization (ISO) has established a minimum light intensity for direct laryngoscopy (DL) of over 500 lux for at least ten minutes, but no such standard exists for Macintosh geometry videolaryngoscope (Mac-VL) blades, which allow for both direct or indirect (videoscopic) viewing of the larynx. Using in situ bench and in vitro testing in a human cadaver, we determined illumination and luminance values delivered by various Mac-VLs and compared these with published minimum lighting benchmarks as well as a reference direct laryngoscope.We tested six Mac-VLs (i-view™, McGRATH™ MAC, GlideScope® Spectrum™ [single-use] DVM S4, GlideScope® Titanium [reusable] Mac T4, C-MAC® S [single-use] Macintosh #4, C-MAC® [reusable] Macintosh #4) together with one direct laryngoscope (Heine LED). Each laryngoscope was assessed with three measurements, as follows: part 1: illuminance (lux) was measured in situ using a purpose-designed benchtop light intensity measurement apparatus; part 2: luminance (light reflected back to the eye) was measured (in candela mIlluminance and luminance varied significantly among the Mac-VLs. Mean (standard devitation) illuminance among the six tested Mac-VLs ranged from 117 (11) to 2,626 (42) lux in the measurement apparatus and from 228 (11) to 2,900 (374) lux by the surgically implanted light meter in the cadaver. All values were less than the reference Heine direct laryngoscope and some fell below the published ISO standard of 500 lux for DL. Luminance testing by spot meter had a similarly wide range, varying from 3.78 (0.60) to 49.1 (10.4) cd·mOur results indicate that illuminance and luminance provided by Mac-VLs used for direct laryngeal viewing varies substantially between devices, with some falling below standards previously suggested as the minimum required for DL. While this may have no implications for the quality of image visible on a device's video monitor, the clinician should be aware that when Mac-VLs are used for direct viewing of the larynx, lighting may not be optimal. This might adversely affect ease or success of tracheal intubation.RéSUMé: CONTEXTE: L’éclairage adéquat du larynx est nécessaire pendant la laryngoscopie pour faciliter l’intubation trachéale. Pour la laryngoscopie directe (LD), l’Organisation internationale de normalisation (ISO) a établi une intensité lumineuse minimale de plus de 500 lux pendant au moins dix minutes. Toutefois, il n’existe aucune norme de ce type pour les lames de vidéolaryngoscope à géométrie Macintosh (VL-Mac), qui permettent une visualisation directe ou indirecte (vidéoscopique) du larynx. Par des études en laboratoire et in vitro sur un cadavre humain, nous avons déterminé les valeurs d’éclairage et de luminance fournies par divers VL-Mac et les avons comparées aux valeurs repères d’éclairage minimal publiées ainsi qu’aux valeurs obtenues avec un laryngoscope direct de référence. MéTHODE: Nous avons testé six VL-Mac (i-view™, McGRATH™ MAC, GlideScope® Spectrum™ [à usage unique] DVM S4, GlideScope® Titanium [réutilisable] Mac T4, C-MAC® S [à usage unique] Macintosh #4, et C-MAC® [réutilisable] Macintosh #4) ainsi qu’un laryngoscope direct (Heine LED). Chaque laryngoscope a été évalué avec trois mesures, comme suit : partie 1: l’éclairage (lux) a été mesuré in situ à l’aide d’un appareil spécialement conçu de mesure de l’intensité lumineuse en laboratoire; partie 2 : la luminance (lumière réfléchie vers l’œil) a été mesurée (en candela m-2 [cd·m-2]) pendant la vidéolaryngoscopie (VL) et la LD sur un cadavre humain, à l’aide d’un posemètre pointé vers la commissure interaryténoïdienne; partie 3: l’éclairage (lux) a été mesuré pendant la VL et la LD sur un cadavre humain à l’aide d’un photomètre implanté chirurgicalement juste en amont des cordes vocales. RéSULTATS: L’éclairage et la luminance variaient considérablement entre les VL-Mac. L’éclairage moyen (écart type) parmi les six VL-Mac testés variait de 117 (11) à 2626 (42) lux avec l’appareil de mesure, et de 228 (11) à 2900 (374) lux lorsque mesuré par le photomètre implanté chirurgicalement dans le cadavre. Toutes les valeurs étaient inférieures au laryngoscope direct Heine de référence, et certaines étaient inférieures à la norme ISO publiée de 500 lux pour la LD. Les essais de luminance par posemètre ont rapporté une plage tout aussi large, variant de 3,78 (0,60) à 49,1 (10,4) cd·m-2, certains VL-Mac offrant moins de luminance que le laryngoscope direct Heine de référence. CONCLUSION: Nos résultats indiquent que l’éclairage et la luminance fournis par les VL-Mac utilisés pour la visualisation directe du larynx varient considérablement d’un appareil à l’autre, certains tombant en dessous des normes précédemment suggérées comme minimalement requises pour la LD. Bien que cela puisse n’avoir aucune incidence sur la qualité de l’image visible sur le moniteur vidéo d’un appareil, le clinicien doit être conscient que lorsqu’un VL-Mac est utilisé pour la visualisation directe du larynx, l’éclairage pourrait ne pas être optimal. Cela pourrait nuire à la facilité ou au succès de l’intubation trachéale.

Svjetlosna jakost osnovna je fotometrijska veličina koja opisuje snagu elektromagnetskog zračenja točkastog izvora u području frekvencije vidljive svjetlosti. Jedan od prvih izvora svjetlosti čija se svjetlosna jakost proučavala bila je svijeća pa se mjerna jedinica za svjetlosnu jakost naziva kandela (lat.candela: svijeća). Definicija kandele mijenjala se kroz povijest. Krajem dvadesetog stoljeća donesena je definicija prema kojoj jedna kandela odgovara svjetlosnoj jakosti jedne svijeće. U ovom završnom radu odredit će se svjetlosna jakost za različite izvore, tj. za svijeće izrađene od pčelinjeg voska i parafina. Dobiveni rezultati usporedit će se međusobno kao i s literaturnom vrijednosti svjetlosne jakosti od 1 cd. Također, u eksperimentu koristit će se i svijeće različitih promjera i debljina fitilja, stoga će se promatrati kako promjer svijeće i debljina fitilja utječu na svjetlosnu jakost. Zaključuje se da svijeće od pčelinjeg voska imaju veću svjetlosnu jakost od parafinskih svijeća te manju relativnu pogrešku. Nadalje, pokazalo se kako svijeće većeg promjera i debljeg fitilja imaju veću svjetlosnu jakost od svijeća manjeg promjera i tanjeg fitilja. Naposlijetku, prikazano je kako se tema završnog rada „Mjerenje svjetlosne jakosti za različite izvore“ može primijeniti u srednjoškolskoj nastavi kao tjedni projekt., Luminous intensity is a basic photometric quantity that describes the power of electromagnetic radiation of a point source in the frequency range of visible light. One of the first light sources whose luminous intensity was studied was a candle, so the unit of measurement for luminous intensity is called the candela (lat. candela: candle). The definition of a candle has changed throughout history. At the end of the twentieth century, a definition was adopted according to which one candela corresponds to the luminous intensity of one candle. In this paper, the luminous intensity will be determined for different sources, i.e. for candles made of beeswax and paraffin. The obtained results will be compared with each other as well as with the literature value of light intensity of 1 cd. Also, candles of different diameters and wick thickness will be used in the experiment, so it will be observed how the diameter of the candle and the thickness of the wick affect the light intensity. It is concluded that beeswax candles have a higher light intensity than paraffin candles and a smaller relative error. Furthermore, it has been shown that candles with a larger diameter and a thicker wick have a higher light intensity than candles with a smaller diameter and a thinner wick. Finally, it was shown how the topic of the final paper "Measurement of luminous intensity for different sources" can be applied in high school classes as a weekly project.

El presente texto analiza las capillas abiertas proyectadas por Félix Candela y Luis Barragán que, a través de las formas de la arquitectura del Movimiento Moderno, reinventan una tipología arquitectónica extendida en la Nueva España. Estas obras resultan un interesante ejemplo del diálogo entre tradición y modernidad sintetizando la historia mexicana al recuperar la espacialidad ceremonial prehispánica, la evangelización tras la conquista y la modernidad arquitectónica posrevolucionaria.

We discuss the candela (cd), the SI unit for light intensity, and its relation to single-photon technology. Currently, the definition of candela is based on the radiant flux in the unit of watts (W) with a fixed constant Kcd, and its primary standard is implemented electrically. Recent advances in the generation and the detection of a single photon indicate that photon-counting techniques with very small uncertainties of less than 1 ppm will become available in the near future. Thus single-photon technology will allow the light intensity to be defined simply in terms of the number of photons counted rather than the power measured in watts.

Felix Candela’s contribution to modern architecture is internationally acknowledged. Regarded rather as structural art than architecture, his notable thin shell structures combine structural ration...

Quantum entanglement is a phenomenon that has no classical counterpart; it is not only difficult to learn but also difficult to teach. It is often an omitted or underrepresented topic in the syllabus of an introductory quantum mechanics or modern physics course. Nearly 40 years ago Mermin published a thought experiment to analyze a device consisting of a transmitter and two receivers. The receivers each had a three-position switch and two lights, one red and one green. Analysis of the operation of the device follows the predictions of quantum mechanics but only simple mathematics is employed to demonstrate the peculiar nature of quantum entanglement. A few years later he reintroduced his quantum device to a more general audience in a Physics Today article and provided another interesting interpretation. In the current paper, we make use of the recently published work in quantum information theory by Candela to have students write code to simulate the operation of the device in that article. Analysis of the device has significant pedagogical value—a fact recognized by Feynman—and simulation of its operation provides students a unique window into quantum mechanics without prior knowledge of the theory.

El techo del vestíbulo principal de la madrileña estación de Sol contiene una de las estructuras más peculiares de toda la red del metro de Madrid. Dentro del tipo de losas planas con nervaduras, al que pertenece, fue diseñado mediante una geometría totalmente original y sin precedentes conocidos. Terminada en 1987, su diseñador fue Félix Candela, y con ella realizó, dentro de su etapa de colaboración con la empresa de ingeniería TYPSA, una obra singular que lo es incluso dentro de su propia y reconocida trayectoria. El objeto de este trabajo es el análisis del diseño de la losa del techo del vestíbulo, con el propósito fundamental de revelar su geometría, poner de manifiesto las particulares propiedades de su dibujo y hacer algunas hipótesis sobre determinados aspectos constructivos relacionados con lo anterior.

Max Borges Jr. (1918 – 2009) was an architect of thin shell concrete structures in Cuba in the 1950's. During this time, Félix Candela (1910 – 1997) owned a construction company that was dedicated to the design and construction of thin shells. Candela also owned an international reputation as a designer of thin shells in the hyperbolic paraboloid (hypar) form. The two men worked together for the first time on a project in Mexico City in 1954, and since then collaborated on several more, most of them in Cuba. This paper illustrates the architect – engineer relationship between Borges and Candela and documents the collaborative projects between them. The research grew out of a course co-taught by the authors, where the course was inspired by the style of teaching of David Billington (1927 – 2018) that integrates engineering with the humanities. Billington believed in scholarship based on historical studies and documentation of heritage structures. This paper is in tribute to this great man who continues to inspire.

High rise buildings or office cubicles constitute the modern living and work places. Rapid pace of urbanization has led to population concentration in cities. Due to space constraints, multi-story buildings in these cities often lack proper access to natural lightening. This necessitates the increasing use of artificial light for illumination even during daytime, leading to higher energy usage in this era of energy crisis. A well-designed Daylight System can deliver daylight to interior parts of buildings, thus reducing dependence on artificial lightening system and to cut energy consumption during the daytime. A daylight illumination system has been presented in this work that made it possible to use PMMA based fiber optic bundle and acrylic lenses as collimator lens reduces heat concentration that arises due to infrared rays at focal point. Numerical simulation for ray tracing and illumination analysis using Trace Pro 7 software has been done. Illumination maps and Polar iso candela have been plotted for collimated and non-collimated beam and it has been observed that collimator lens results in uniform distribution of light rays without any hot spot formation.

We demonstrate an iterative and inverse design of a segmented reflector used to illuminate the road with a uniform light distribution and reduced glare to the oncoming traffic. Design is set to meet the StVZO standard. The maximum brightness obtained is 1460 candela, which is five times brighter than a conventional headlamp of urban shared electric scooters and bicycles, resulting in improved visibility in dark environments. A prototype was built and tested at various environments. The tolerance analysis showed no negative influence on the desired standard light distribution. In addition to this iterative approach, a ray tracing code has been developed for inverse design and to map a desired uniform road illumination pattern back to the candela sensor for corresponding reflector design.

The idiosyncratic 1958 thin shell roof of Los Manantiales restaurant in Xochimilco, south of Mexico City, designed by master Felix Candela, became a model often replicated during the following 50 years. The appearance of this futuristic shell was Candela’s dream design, a seed planted in Mexico that then flourished across four continents. This replicating phenomenon is hereby studied chronologically through seven case studies. For each case study, the investigation briefly discusses the background behind its construction, gives a profile of its designers, explores similarities and differences in construction methods vis-a-vis those used in Xochimilco, and considers whether the structure subsequently acquired local or national prominence. During his lifetime, Candela was pleased that his ideas were adopted and developed by other practitioners, and lessons can be learned from Candela’s work and from the sequels it inspired.

The conservation problems related to the concrete-built heritage during the 20th century entail the technical difficulties inherent to material nature and the applicable theoretical criteria. Due to the lack of value significance, protection, legal gaps, and ignorance on technical procedures, these architectures have become vulnerable worldwide. The problem is particularly important for concrete shell structures because, concrete research has mainly focused on rigid frames buildings, which have a different structural behavior than shells The conservation and intervention in concrete shells require a particular methodological approach that encompasses understanding of the structure and geometry, material behavior, construction systems, and deterioration mechanisms. From this knowledge, it is possible to come up with adequate solutions that help to safeguard shell heritage. These actions must be complemented with academic studies and dissemination among the population and users to publicize the heritage importance that it implies. The work of Félix Candela is one of the worldwide examples that entail this type of structures. The meaning and cultural value his structures possess are due to the architectural and technical expression, but also from the economic, social, and political context in México that allowed the development and construction. Despite this, due to the lack of patrimonial declarations and gaps in the country’s legislation, the works are at constant risk of degradation and loss. This research will review and critically analyze the state of conservation of selected shell structures of Candela in Mexico and expose their value and heritage significance. Then, based on the conservation guidelines proposed by international and national organizations, a series of applicable recommendations will be presented to carry out appropriate interventions and actions that guarantee their preservation

The revised SI, which came into force on May 20th, 2019, bases the system of units on fixed numerical values of constants of nature, so-called "defining constants". An overview of the changes implemented by the revised SI will be presented with an emphasis on the consequences for the unit candela and the unit second; namely, the realization of a traceable, quantum-based candela and a possible redefinition of the unit second. Prospects of time scales and time and frequency transfer will be given.

This paper presents a contemporary architectural working method that encompasses digitalization and parameterization of existing buildings and optimization of new buildings designed with ruled surfaces. The method uses parametric modeling and computational structural analysis in order to simplify contemporary building processes. As an example of the application of these techniques, in this paper they are applied to Felix Candela’s Church of St. Joseph the Craftsman, a design which features hyperbolic paraboloids that are considered difficult to design, calculate and build. The optimization method introduced in this paper seeks to explore different possibilities for designing and modifying buildings designed using non-standard geometry allowing them to be built out of simplified elements but also keep construction and visual properties of their shape. This method is also useful for students and young engineers to expand their skills in structural analysis, parametric modeling and optimization methods with contemporary tools.

This abstract describes the Data Fusion tool of the Horizon 2020 CANDELA project. Here, Sentinel-1 (synthetic aperture radar) and Sentinel-2 (multispectral) satellite images are fused at feature level. This fusion is made by extracting the features from each type of image; then these features are combined in a new block within the Data Model Generation sub-module of the Data Fusion system.The corresponding tool has already been integrated with the CANDELA cloud platform: its Data Model component on the platform is acting as backend, and the user interaction component on the local user machine as frontend. There are four main sub-modules: Data Model Generation for Data Fusion (DMG-DF), DataBase Management System (DBMS), Image Search and Semantic Annotation (ISSA), and multi-knowledge and Query (QE). The DMG-DF and DBMS sub-modules have been dockerized and deployed on the CANDELA platform. The ISSA and QE sub-modules require user inputs for their interactive interfaces. They can be started as a standard Graphical User Interface (GUI) tool which is linked directly to the database on the platform.Before using the Data Fusion tool, users have to prepare the already co-registered Sentinel-1 and Sentinel-2 products as inputs. The S1tiling service provided on the platform is able to cut out the overlapping Sentinel-1 area based on Sentinel-2 tile IDs.The pipeline of the Data Fusion tool starts from the DMG-DF process on the platform, and the data will be transferred via Internet; then local end users can perform semantic annotations. The annotations will be ingested into the database on the platform via Internet.The Data Fusion process consists of three steps:On the platform, launch a Jupyter notebook for Python, and start the Data Model Generation for Data Fusion to process the prepared Sentinel-1 and Sentinel-2 products which cover the same area; On the local user machine, by clicking the Query button of the GUI, users can get access to the remote database, make image search and queries, and perform semantic annotations by loading quick-look images of processed Sentinel-1 and Sentinel-2 products via Internet. Feature fusion and image quick-look pairing are performed at runtime. The fused features and paired quick-looks help obtain better semantic annotations. When clicking on another ingestion button, the annotations are ingested into the database on the platform; On the platform, launch a Jupyter notebook for Python, and the annotations and the processed product metadata can be searched and queried. Our preliminary validation results are made based on visual analysis, by comparing the obtained classification maps with already available CORINE land cover maps. In general, our fused results generate more complete classification maps which contain more classes.

Following many years of intense investigations, leading to significant progress with the determination of fundamental constants, it is now likely that the General Conference for Weights and Measures (CGPM) will approve revised definitions for the SI base units at its next meeting in November 2018. It is proposed that the definitions for the kilogram, the ampere, the kelvin, and the mole will be based on new physical concepts, whereas the definitions for the second, the meter and the candela will only be reformulated. As a consequence, the units of the revised SI would be derived from a set of seven defining constants. This article describes the principal shortcomings of the present SI, the planned changes and the consequences for the realization and dissemination of units in the different fields of metrology.

The legacy of master builder Felix Candela is cemented by his widespread adoption of thin hyperbolic paraboloid (hypar) umbrellas within architecture across the Americas. Exhibiting any number of edges, with or without parabolic bisectors, these inverted umbrellas perfectly embody the amalgamation of efficiency, economy, and elegance as emblematic of structural art. Yet, a consistent mathematical description of their unique form does not presently exist in the literature. As such, Candela’s umbrellas have rarely been the subject of rigorous structural analysis, nor frequently featured in contemporary architectural planning. This paper introduces equations to parametrize the geometry of hypar umbrellas with any arbitrary number of edges and parabolic bisectors for analysis and design applications. A simplified method computing the surface area of Candela’s umbrellas based on regular pyramids is also presented. As such, this work provides an exact geometrical description of N-sided hypar umbrellas, thus removing the need for manual surface generation via computer-aided design (CAD) prior to numerical analyses.

Fishermen generally use light as a common way to attract fish in the fishing industry. This study aimed to design a model of an underwater fishing using Light Emitting Diode (LED) lamp which is less costful and suitable for fishermen of Tanzania. Most fishermen currently use kerosene based lamps like candela which consumes lots of energy leading to high cost in terms of money used to regenerate the energy. This running cost automatically rises up the price of fish in the market. Thus with the use of LED lamp the cost will be reduced. The findings from this study showed that the LED lamp consumes little amount of energy (energy saving) compared to candela lamp which consumes 6 liters of kerosene per 36 hours which is equivalent to three nights, while the LED lamp takes 7 batteries at once for 36 hours. The 6 liters of kerosene cost around 7 USD and that of 7 batteries cost is near 2 USD. The LED lamp can be accessed by only 15 USD the price which is nearly half the price of the candela lamp. The candela lamp in the market is sold around 31 USD. This shows that LED lamp is more efficient in terms of conserving energy and cost effective than candela lamp. It is recommended that fishermen in the fishing industry in Tanzania should employ the usage of underwater LED fishing lamps as they are energy efficient. This will help the fishermen of Tanzania to undertake the fishing activity at low cost which will result to the decrease of price of fish in the market. This shows that this LED lamp has high efficiency and effectiveness to be used by fishermen compared to traditional method used by majority of them.

Recently, the laser therapy for a treatment of the skin lesions of the vascular origin has gained a substantial development, and progress in the technical area. The vascular lasers, particularly the CANDELA Vbeam Perfecta, which is a part of this research has been equipped by a system of the dynamical cooling, called DCD leading to a higher patient’s comfort during the examination. In the most of the vascular lasers, it was allowed for settings of the pulse length up to 40 ms. By this way, the hematomas are reduced after the treatment, and mostly the skin is only getting red. For a reason of a complexity of the CANDELA Vbeam Perfecta settings, on a demand of the physicians, the user environment has been developed serving for an automatic parameters calculation of the laser therapy, and possibilities of alternative settings for same laser energy. The software environment has been designed in the MATLAB. The SW has been tested in the clinical conditions of the University Hospital of Ostrava.

This paper examines the effectiveness of coelostat daylighting systems for enhancing the indoor visual environment of open-plan offices. A coelostat consists of a movable mirror capable of tracking the sun and a fixed second mirror, which, acting together, create a single beam of sunlight for daylighting. A series of computer simulations were carried out using TracePro and Radiance where the relevant IES output (polar candela distribution plots) of the former was exported to the latter for photometric analyses. The results reveal that coelostat daylighting systems can significantly enhance not only the visual environment but also the energy efficiency when sufficient daylight is introduced by simultaneously applying side and top daylighting (ST) schemes. When only daylight admitted through windows is considered, daylight availability varies from 0.12% (at 10 a.m., summer solstice) to 3.19% (at 12 p.m., winter solstice). In contrast, the highest daylight availability of 3.41% is observed at 12 p.m. on the day of the winter solstice when side and top lighting are considered in addition to daylight admitted through windows. Electricity savings of 1.78 kWh are estimated over a period of one hour around noon, that is, a half an hour before and after noon. A comparison between the on-site measured data and simulated values showed that they were in good agreement, confirming the reliability of the computer modeling developed in this work. The approach described here could be extended to analyze daylighting performance of buildings with similar solar features, such as light wells.

High dynamic range (HDR) and wide color gamut (WCG) technology present challenges to the design of a test pattern for the visual verification of systems. The previous International Telecommunications Union (ITU-R) Recommendation BT.709 paradigm defined a “zero-to-one-hundred-percent” scale, and the entire system and any reasonable display could be expected to show the full range of code values. However, SMPTE ST 2084 defines an absolute correspondence from code values up to 10,000 nits (A nit is a unit used to measure brightness and is equivalent to a candela per square meter), and even professional monitors will clip at some lower brightness level unique to their particular design. Furthermore, the ITU-R BT.2020 color gamut “container” exceeds the gamut of any professional monitor, so colors that are outside of a monitor's particular gamut capability will be modified by the monitor. This lack of dependable behavior of monitors at the extremes of color and brightness creates additional challenges for the design of visual test patterns.

In this paper, the surface morphologies of 4H-SiC epilayers with different growth rates were investigated by Candela CS920, atomic force microscope and optical microscope. The investigation of the surface morphologies of the samples showed that an evolution from micro-step to small-step and then back to macro-step occurred on the surface, with the surface roughness increased gradually during this evaluation. It was concluded that the higher growth rate the larger differences of step migration rate. In this case, the steps easily gather together forming greater steps. The gathering effect was enhanced with the increase of the growth rate.

A new LED rear light for automotives is proposed and demonstrated for EU ECE R07 regulation. The full rear light is a combination of a position lamp and a braking lamp, and LED light bars and micro-prisms are involved as their essential components. The micro-prisms are applied to homogenize the output of the rear light to decrease glare and accomplish EU ECE standard. Through experiments, it is shown that EU ECE R07 regulation can be met in the proposed rear light, and 12% (position lamps) and 26.5% (braking lamps) higher candela can be enhanced after the optimization of micro-prisms.

Die Physikalisch-Technische Bundesanstalt (PTB) als nationales Metrologieinstitut Deutschlands stellt die Rückführung auf die Einheiten des internationalen Einheitensystems (SI) für die deutsche Industrie zur Verfügung. Dies erfordert eine stabile Darstellung der jeweiligen Einheiten und eine genaue Kenntnis der assoziierten Messunsicherheiten. Vor diesem Hintergrund wurde in der vorliegenden Dissertation ein neuer Detektor für eine verbesserte radiometrische Rückführung der photometrischen Lichtstärkeeinheit Candela entwickelt. Die Lichtstärke als photometrische Größe ist rückgeführt auf die Messung einer optischen Strahlungsleistung. In der derzeitigen Rückführungskette erfolgt der Transfer von der optischen Strahlungsleistung zur Lichtstärke schrittweise an vier unterschiedlichen Kalibriermessplätzen mit jeweils unterschiedlichen Transferdetektoren. Zur Verbesserung der Rückführung sind die einzelnen Komponenten des neuen modularen Detektors gezielt ausgewählt und entwickelt worden. Die Verwendung eines sog. Trapdetektors basierend auf Silizium Photodioden ermöglicht dessen direkte und genaue Kalibrierung bzgl. der optischen Strahlungsleistung. Ein zusätzlich angefügtes Filtermodul erlaubt die direkte Messung von Lichtstärken. Die Charakterisierung des Detektors und alle Messungen, die zum Transfer einer Strahlungsleistungsempfindlichkeit in eine photometrische Empfindlichkeit nötig sind, werden mit Hilfe von durchstimmbaren Lasern am TULIP-Aufbau (Tunable Lasers in Photometry) der PTB durchgeführt. Die vollständige modulare Charakterisierung an einem einzelnen Messaufbau, sowie der Verzicht auf weitere Transferdetektoren erlauben eine potenzielle Reduktion der Messunsicherheit gegenüber der derzeitigen radiometrischen Rückführung. Auf Basis von Voruntersuchungen bisher verwendeter Filterelemente wurden Simulationen durchgeführt, um für den Detektor optimierte Blenden und Filterelemente aufzubauen. Diese Filter und Blenden zeigen aufgrund angefügter Keilelemente eine geringere Modulation der Transmission durch Interferenzeffekte als bisherige planare Filter. Dieser neue, sogenannte V(λ)-Trapdetektor wurde im Rahmen dieser Arbeit - basierend auf der derzeitigen Rückführungskette - bezüglich seiner spektralen Strahlungsleistungs-empfindlichkeit, seiner spektralen Bestrahlungsstärkeempfindlichkeit und seiner photometrischen Empfindlichkeit kalibriert. Die entsprechenden Messungen haben die Eignung des Detektors mit den jeweiligen Modulen für die einzelnen Kalibrierschritte der neuen Rückführung gezeigt. Bei der Betrachtung der Messunsicherheit hat sich gezeigt, dass der neue Detektor verglichen mit der aktuellen Rückführungskette eine verringerte Messunsicherheit für die photometrische Empfindlichkeit ermöglicht. Auf Basis der Ergebnisse werden optimierte Messstrategien vorgeschlagen, die die kommende neue Realisierung der Candela mit möglichst geringer Messunsicherheit ermöglicht.

In the present work it is explained how the architect Felix Candela got to analyse the roof long cylindrical shells in reinforced concrete using an method based simply on equilibrium equations. All this, in a moment in which the elastic theory of shells becomes practically impossible to apply due to the involvement of eighth-order differential equations. Felix Candela 'objective was to get a safely and easily calculation method, respecting the assignment of reinforced concrete and, therefore, obviating the considerations of compatibility and deformation that could undergo the structure. This method, developed previously by other engineers, is explained mathematically choosing an example of work of Félix Candela, done by roof long cylindrical shells, and making the necessary structural calculations proposed., En el presente trabajo se describe cómo el arquitecto Félix Candela llevó a cabo el análisis de cáscaras cilíndricas largas de cubierta de hormigón armado utilizando un método basado simplemente en ecuaciones de equilibrio. Todo ello, en un momento en el que la teoría elástica de cáscaras cilíndricas resultaba prácticamente inaplicable al implicar la resolución de ecuaciones diferenciales de octavo orden. El objetivo de Félix Candela era obtener un método de cálculo seguro y sencillo, respetando la característica de cedencia del hormigón armado y, por tanto, obviando consideraciones de compatibilidad y deformación que pudiera sufrir la estructura. Este método, desarrollado anteriormente por otros ingenieros, se expone matemáticamente seleccionando un ejemplo de la obra de Félix Candela, ejecutada por medio de cáscaras cilíndricas largas, y elaborando el proceso de cálculo necesario propuesto.

Deployable four-sided hyperbolic paraboloid (hypar) umbrellas inspired by the architecture of Felix Candela have been conceptualized as a feasible countermeasure against surge-induced coastal inundation. Referred as Kinetic Umbrellas, such structures may readily deploy from an open canopy to form a physical barrier prior to imminent coastal hazard scenarios. This paper presents a parametric investigation into the structural behavior of Kinetic Umbrellas exhibiting rise/area ( r ∕ A ) ratios from 0 to 0.045 m−1 subject to hydrostatic inundation ranging from 50% to 100% of the total deployed height. An analytical method for the discretization of hydrostatic forces on tilted hypar manifolds was developed and validated, enabling the determination of internal forces and deformations within the umbrella and supporting column via finite element modeling. All critical demands were highly influenced by the lateral column rigidity for any given r ∕ A , to which a ratio of 0.03 m−1 was revealed as optimal for the minimization of shell stresses. Longitudinally asymmetric umbrellas were also analyzed and were discovered to exhibit inferior structural performance relative to their doubly-symmetric counterparts. Finally, concrete reinforced with glass fiber polymers was demonstrated as a feasible material for such structures even at the maximum level of inundation. This work ultimately provides insight into the holistic response of Kinetic Umbrellas to aid their prototyping and design for practical engineering applications.

Initial results from a custom, 3x150 mm horizontal hot-wall, SiC Vapor-Phase epitaxial growth reactor (VPE), with full planetary motion are reported. Epitaxial layer properties are compared with those grown on previously reported 1x150 mm hot-wall and 6x150 mm warm-wall reactors for epitaxial wafers of up to 100 microns thickness. The median intra-wafer thickness and doping uniformity (σ/mean) for the 3x150 mm reactor are 0.9% and 6.10%, respectively. The intra-run thickness and doping variation are 0.18% and 1.01%. The projected 5x5 mm useable area for layers of nominal 5 to 30 μm thickness for all the reactor configurations (as measured by a Candela CS2 optical surface analyzer) are approximately 92%, corresponding to an effective defect density of about 0.35 cm-2. Useable areas as high as 86.5% and 1-2 nm rms roughness have been observed for layers of over 100 μm thickness. Initial morphological results using a higher resolution, LaserTec SICA6X confocal differential interference contrast (CDIC) microscope, are also presented.

Recent decisions of the General Conference on Weights and Measures of the Metre Convention have opened the door to a fundamental change of the International System of Units, the SI, in 2018. The revised SI will be based on fixing the numerical values of seven defining constants corresponding to the seven traditional base units. This will bring about basic modifications in the definition of the kilogram, the ampere, the kelvin, and the mole and will have consequences for units derived from them. In contrast, the second, the meter, and the candela will not be affected. This paper describes the motivation and rationale behind this endeavor, introduces the new definitions, and reviews the requirements for the redefinitions as well as the status of the experiments that are currently being carried out to fulfill them. Benefits and a wide-reaching impact for the realization and dissemination of the units are anticipated because innovative technologies with ever-increasing accuracy will emerge, enabling the direct realization over widespread measurement ranges without the definitions themselves having to be changed.

Structural artist Felix Candela pioneered the 8-sided hyperbolic paraboloidal (hypar) umbrella by introducing a parabolic discontinuity bisecting each quadrant of the classical 4-sided form. While artistically striking, such structures have never been rigorously examined from a structural engineering perspective. This paper formulates equations governing the geometry of 8-sided hypars, facilitating the in-depth analysis and comparison against their more common 4-sided variants via finite element modeling. A parametric investigation based on two historical case studies identified that 8-sided umbrellas exhibit larger deflections and stresses relative to 4-sided renditions, thus rebuking Candela’s hypothesis concerning the improvement to structural efficiency offered by the parabolic fold. While corner deflections and principal stresses generally decrease with increasing curvature, the discontinuity present in 8-sided forms disrupt the flow of internal forces, resulting in stress concentrations at the parabolic apex manifesting as large moment demands. However, it was demonstrated that 8-sided hypars exhibit increased resistance to shell buckling over 4-sided variants as revealed through a simplified analytical approach.

Eye tracking is mainly employed as mean of tracking visual attention of an observer/operator. Still, eye tracking is also capable of recording a wider variety of data such as traces of mental workload. Pupil diameter have been validated as such measure. Most of the studies that have validated this are in laboratory conditions, where the perceived luminance (measured in candela per square meter) can be controlled. Luminance affects the pupil diameter as well; this means if the pupil diameter varies for an operator/observer in field conditions it cannot be accurately determined if the change in the pupil diameter is due to mental workload alone. Although there are some studies, which have attempted to simultaneously account for the contribution of the change in pupil diameter due to luminance and mental workload, not many have attempted to account for this in field conditions for safety-critical systems such as a helicopter or a maritime ship bridge. In this study as a first step, we define a method to measure luminance while tracking the gaze point. We will record eye-tracking data simultaneously recording the video feed of the field of view of the operator/observer. We will use the video feed to estimate the luminous flux from the point of view of the subject. We will be collecting this data from a helicopter pilot and his co-pilot during an actual operation (e.g. transportation of personnel and carrying a payload for an electrical power provider company in Norway or Sweden). We will also be collecting data from a navigator and his first officer in a high-speed marine craft of the Norwegian navy. We will also be collecting subjective data using paper-based tools such as NASA-TLX in addition to a conventional video recording of the scene of activity and handwritten notes of observation for validation purposes. We will also capture mental workload data from a few other objective sources such as heart rate variability (ECG). We expect to clearly define an approach to separately account for the effect of mental workload independent of the impact of changing light conditions in field situations for safety-critical systems. This includes a mathematical model that we innovate based on other mathematical models that are already available in the literature.

The International System of Units (SI) is founded on 7 SI base units (meter, kilogram, second, ampere, kelvin, mole, candela) for 7 base quantities (length, mass, time, electric current, thermodynamic temperature, amount of substance, luminous intensity) assumed to be mutually independent. There is a need for a new quantity that describes the quality or type of the substance. The processing and introduction of this quantity is investigated. The method of the maximum possible atomic number of elements in Mendeleev’s Periodic Table was used. Here is a proposal of the 8th base quantity called type of substance and its unit boscovich, B. This quantity cannot be derived from 7 existing quantities and therefore should be introduced as a separate new one. It is also explained why the unit boscovich for type of substance is suggested.

Light-emitting diode (LED) modules can be flexibly disassembled and assembled and have inherent advantages in large-area lighting applications. In this paper, an efficient method is proposed to design an LED freeform lens array for direct lighting based on an adjustable Cartesian candela distribution. The Cartesian gradient candela distribution (CGCD) is adjusted and determined through the initialized design of a single freeform lens and a diffuser plate. The layout of the LED lens array can then be optimized by controlling the semi-angle of the light intensity distribution (SALI). A design example shows that the uniformity of the lens array increases by 11.63% through only a two-round iterative optimization. Both the simulation and experimental results are discussed to verify the proposed design. The freeform lens array is expected to expand the applications of mini- or micro-LED devices.

This document brings together the definitions and the tables of numerical values for photometry already adopted (or recommended) and published, by the Conference Generale des Poids et Mesures (CGPM), by the Comite International des Poids et Mesures (CIPM), or by the Commission Internationale de l'Eclairage (CIE). This document provides the link between the definition of the candela in the International System of Units (SI) and the internationally agreed spectral luminous efficiency functions for human vision published by the CIE, including those for mesopic vision and for photopic vision for a 10° field of view, in addition to those for photopic vision for a 2° field of view and for scotopic vision. The definitions of photometric units and quantities have also been updated with the reformulated definition of the candela in the International System of Units (SI) 2019 and the latest definitions of the photometric quantities by the CIE.

[ES] El artículo describe el proceso llevado a cabo para la realización de un proyecto de investigación cuyo objetivo era la reconstrucción de superficies parabólico-hiperbólicas de una selección de proyectos no construidos de Félix Candela.El flujo de trabajo seguido para la reconstrucción se ha basado en un proceso de automatización. Tras definir las variables necesarias y establecer un diseño procedural, se han podido obtener las variaciones de los proyectos de Candela.La reconstrucción virtual se ha llevado a cabo mediante modelos parametrizados realizados con Grasshopper y de manera experimental con Houdini FX.Los resultados son válidos no solo para su discusión científica, sino que también pueden tener un papel educativo en la geometría y la comunicación., [EN] The paper explains the process used in a research project whose objective was the reconstruction of the hyperbolic-parabolic surfaces of a selection of non-built projects designed by Félix Candela.The workflow was based on an automation process. After setting up the variables and define a procedural design, it has been possible to obtain the variation of the projects designed by Candela.The virtual reconstruction was done using models parameterized with Grasshopper and experimentally with Houdini FX.The results are valid not only for their scientific debate but also can have an educational role in the fields of geometry and architectural communication.

This paper describes the methods and results obtained in the reconstruction of ruled surfaces from a selection of non-built projects by Felix Candela. The amount of work done during the project was possible because of the parametric methods and the programming code used during the reconstruction. The aim of the paper is to show the workflow, the procedures and the processes carried out for the virtual reconstruction of the projects. The communication focuses on the projects done by hyperbolic parabolic surface fragments. The models are based on the original designs of Felix Candela, which respond to different structural types. Thanks to the digital reconstruction we can appreciate how the projects would have been if they had been built. In addition, the models can be exported to virtual reality systems or materialized as physical models through digital manufacturing. Given the graphic nature of the project, the article presents original images made by the authors, some corresponding to unpublished projects by Felix Candela. The educational nature implicit in this kind of workflow has led to its inclusion in different workshops in several Architecture Schools in Europe, where students can experiment with different approaches in the fields of geometry and computation.

High-dynamic-range (HDR) technology has attracted a lot of attention recently, especially in commercial trade shows such as the Consumer Electronics Show, the National Association of Broadcasters Show, the International Broadcasting Convention, and Internationale Funkausstellung Berlin. However, a great deal of mystery still surrounds this new evolution in digital media. In a nutshell, HDR technology aims at capturing, distributing, and displaying a range of luminance and color values that better correspond to what the human eye can perceive. Here, the term luminance stands for the photometric quantity of light arriving at the human eye measured in candela per square meter or nits. The color refers to all the weighted combinations of spectral wavelengths, expressed in nanometers (nm), emitted by the sun that are visible by the human eye (see Figure 1). The human eye can perceive a dynamic range of over 14 orders of magnitude (i.e., the difference in powers of ten between highest and lowest luminance value) in the real world through adaptation. However, at a single adaptation time, the human eye can only resolve up to five orders of magnitude, as illustrated in Figure 2. Dynamic range denotes the ratio between the highest and lowest luminance value. As reported in Table 1, there are different interpretations for dynamic range, depending on the application. For instance, in photography, dynamic range is measured in terms of f-stops, which correspond to the number of times that the light intensity can be doubled.