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In this thesis, the author developed a retroreflective sheeting selection technique for traffic signs. Previous research was used to determine the luminance needed by drivers (demand luminance). The author used roadways scenarios to determine the amount of luminance the retroreflective sheeting on a sign would produce (supply luminance). A spreadsheet was developed to determine the performance of different retroreflective sheeting types by comparing the demand and supply luminance for specific roadway scenarios. Using the results of previous studies, three demand luminance levels were created: replacement, adequate, and desirable. The replacement level represents the level of luminance when a sign needs to be replaced and is 2.5 cd/m2. The adequate level is the recommended amount of luminance when installing new traffic signs and is 10 cd/m2. The desirable level is the approximate level when additional luminance has diminishing returns and is 30 cd/m2. Supply luminance on a specific traffic sign was determined by evaluating roadway geometries, sign placement, retroreflective sheeting type and vehicle data. The author reviewed roadway geometries in Texas to estimate typical number of lanes, shoulder widths and horizontal curvature in the US. Sign placement from the MUTCD determined the typical lateral placements, sign heights, and sign twists. Vehicle data included vehicle dimensions and headlamp type. Both the supply and demand luminance were determined for a specific viewing distance for a given scenario. The viewing distance is the distance a driver needs to read or recognize a sign to respond properly. In addition, the type of sign, alphanumeric or symbol, determined how this distance was calculated. The author developed four sign groups to calculate the distance required to read and respond to a traffic sign, including 1) Stop required, 2) Reduction in speed required, 3) Read the message provided, and 4) Change of lane required. For symbol signs, the minimum required visibility distance (MRVD) was determined for the sign group and for text signs, the viewing distance at a legibility index (LI) of 30 ft/in was found. At these distances, the author calculated the supply luminance and then compared it to the demand luminance levels to determine the performance level. The author developed the Retroreflective Sheeting Selection Spreadsheet (RSSS) to allow others to use the methodology presented in this thesis. RSSS allows users to input the roadway data, vehicle data, and sign data. RSSS takes this information and looks up the supply luminance for the scenario. RSSS then compares the supply luminance to the demand luminance levels and outputs the retroreflective sheeting performance level for the scenario.

Most shading device systems installed in windows or glass walls are used only for protection from overheating and glare, neglecting other possible functions, such as increasing the daylight level in the space or collecting solar energy. The blinds are usually made of opaque or translucent materials, and if they are partially open/closed or completely closed, a direct view to the outside is blocked. A balance between a sufficient amount of daylight and protection from overheating of the space in summer is not often achieved due to inappropriate control of the blinds’ tilt angle. There is also a need for specific guidance for the selection and design of shading device systems in the windows. This research develops a general decision-making framework (DMF) that can be used by architects and manufacturers of shading devices. The general DMF is a guide for the user in analyzing shading device performance in the process of selection/design of the shading device. This research also develops a specific DMF to better understand and validate the general DMF. The specific DMF, based on illuminance and luminance, is used for an analysis of daylighting performance of shading devices to select the best possible existing system or new system among several alternatives. Architects or manufacturers of shading devices, as the users of the DMF, analyze various systems of blinds applied on a particular building and at a given location. The users of the DMF can apply either an experimental procedure or computer simulation that provides information about illuminance and luminance levels in the space. Based on the analysis of the results of the experiments or simulations, the user of the DMF decides which blinds to select. The specific DMF proposes a methodology for both the analysis of the daylighting performance and for the process for making a decision based on the results of the analysis. A case study is conducted in order to validate the DMF. Three types of shading devices are tested: an existing system, a patented system, and a new system, proposed by this research. The shading devices are installed in an office space located in Roanoke, Virginia. The software Autodesk VIZ 4 is used to simulate daylighting performance. The output information, such as illuminance and luminance levels in the space, is used as a basis for making the decision about which type of blinds to apply. A new system of shading device, which has a triangular cross section and is made of clear plastic with a silver coating on one side, shows better performance than the existing shading device and the patented shading device, given the research limitations. By using the specific decision-making framework, a shading device manufacturer/designer is able to understand the shading device daylighting performance from his design-imposed criteria. Selection of the shading device, given the designer's daylighting objectives, is better achieved. Existing shading devices are also able to be analyzed from a building designer's perspective. This analysis is based on the designer-imposed daylighting criteria. The specific decision-making framework helps the designers of the buildings, together with the clients, select the most appropriate shading device based on daylighting performance. The decision-making framework is a model for development of decision-making software that will help designers of buildings, facades, and shading device systems in the selection/design of shading device systems in all phases of the design. / Ph. D.

The analysis of the illumination devices at work have been performed, methods of illumination calculation and their simplified forms have been presented. The set requirements for the lighting systems have been analyzed and the program of the lighting calculation has been investigated. Experiment on measuring the amount of illuminance on the working surface of the room has been executed and the data of experiment has been compared with the calculation results. It has been measured that the data of experiment coincides with the calculation results. Seven separate lighting systems have been examined; their efficiency of lighting the whole working surface and separate working places has been measured. The research on uniformity of illuminance on the whole working surface and separate working places has been performed. The influence of the objects that exist in the room, such as monitors, workers, on the efficiency and uniformity of illuminance in the working places has been examined. Deficiencies and advantages of separate lighting systems have been explained in the performed research. The received results are summarized in the conclusions.

This study evaluated the usefulness of a psychophysical model as part of a new ANSI/HFES 100 standard for CRT flicker. A graph based flicker prediction method developed from Farrell, 1987 was evaluated. The Farrell model is based on phosphor persistence, screen luminance, display size, and viewing distance. The graph based method assumes a worse case scenario (i.e. a white display screen shown on a display with P4 phosphor). While the Farrell model requires photometric measurements to be taken using special equipment, the graph based method require a knowledge of the display size, viewing distance, screen luminance, and refresh rate. Ten participants viewed different display sizes from different eccentricities under different levels of illumination and luminance. In each condition the display's refresh rate was manipulated using the Method of Limits to determine the critical flicker frequency (CFF). An Analysis of Variance was used to detirmine significant effects on CFF. CFF increased with increasing luminance and display size. Adequate illumination significantly increased CFF. A viewing eccentricity of 30 degrees (measured horizontally from the center of the screen) produced the highest CFF values. Under the conditions of 30 degrees eccentricity and 250 to 500 lux illumination, observed 50% CFF threshold values exceeded the 90% CFF threshold values predicted by the graph based method. This study demonstates that when tested under the same conditions it was developed under, the Farrell method successfully predicts flicker perception; however, when tested under conditions representative of real world working conditions, the Farrell model fails to predict flicker perception. New parameters for the model are suggested.<INPUT TYPE="hidden" NAME="abstract" VALUE="This study evaluated the usefulness of a psychophysical model as part of a new ANSI/HFES 100 standard for CRT flicker. A graph based flicker prediction method developed from Farrell, 1987 was evaluated. The Farrell model is based on phosphor persistence, screen luminance, display size, and viewing distance. The graph based method assumes a worse case scenario (i.e. a white display screen shown on a display with P4 phosphor). While the Farrell model requires photometric measurements to be taken using special equipment, the graph based method require a knowledge of the display size, viewing distance, screen luminance, and refresh rate. Ten participants viewed different display sizes from different eccentricities under different levels of illumination and luminance. In each condition the display's refresh rate was manipulated using the Method of Limits to determine the critical flicker frequency (CFF). An Analysis of Variance was used to detirmine significant effects on CFF. CFF increased with increasing luminance and display size. Adequate illumination significantly increased CFF. A viewing eccentricity of 30 degrees (measured horizontally from the center of the screen) produced the highest CFF values. Under the conditions of 30 degrees eccentricity and 250 to 500 lux illumination, observed 50% CFF threshold values exceeded the 90% CFF threshold values predicted by the graph based method. This study demonstates that when tested under the same conditions it was developed under, the Farrell method successfully predicts flicker perception; however, when tested under conditions representative of real world working conditions, the Farrell model fails to predict flicker perception. New parameters for the model are suggested." / Master of Science

Abstract Today, digital imaging is widely used in dentistry. In medical radiography, the importance of displays and room illuminance has been shown in many studies, whereas the effect of these factors in the diagnosis of dental radiography is not clear and remains controversial. There is limited knowledge among dentists as to how observer performance is affected by the type of display, level of ambient light or grayscale calibration. The aim of this thesis was to compare observer performance in the detection of both anatomical structures and pathology in panoramic and bitewing radiographs using consumer grade display with γ 2.2- and DICOM-calibration, a tablet (3rd generation Apple iPad® and a 6 MegaPixel (MP) display under different lighting conditions. Furthermore, the thesis aimed at providing recommendations for type of display and acceptable illuminance levels in the room for interpretation of dental radiographs. Thirty panoramic and bitewing radiographs were randomly evaluated on four displays under bright (510 lx) and dim (16 lx) ambient lighting by two observers. Both anatomical structures and pathology were evaluated because they provided both low- and high-contrast structure. Consensus was considered as reference. Intra- and inter-observer agreement was determined. The proportion of equivalent ratings and weighted kappa were used to assess the reliability. The level of significance was set to P&lt;0.05. DICOM calibration may improve observer performance in the detection of pathology in panoramic radiographs regardless of the room illuminance level. DICOM calibration improves the detection of enamel and dentinal caries in bitewing radiographs, particularly in bright lighting conditions. On the other hand, in dental practice the room illuminance level is often higher, and it is thus recommended that the overall lighting level should be decreased. Furthermore, a DICOM-calibrated consumer grade display can be used instead of a medical display in dental practice without compromising the diagnostic quality and it saves costs. Tablet displays are recommended to use with care in dental radiography. / Tiivistelmä Hammaslääketieteessä käytetään nykyään pääasiassa digitaalista kuvantamista. Lääketieteellisessä radiologiassa näyttöjen ja käyttöympäristön valaistuksen merkitys kuvien katseluun on osoitettu lukuisissa tutkimuksissa, kun taas hammaslääketieteellisten tutkimusten tulokset näiden tekijöiden vaikutuksista röntgenkuvien tulkintaan eivät ole yksiselitteisiä ja niissä on ristiriitaisuutta. Hammaslääkäreiden tiedot näyttöjen, kalibroinnin ja ympäröivän valaistuksen vaikutuksesta röntgenkuvan tulkintaan ovat puutteellisia. Tämän väitöskirjan tarkoituksena oli vertailla näyttöjen suorituskykyä panoraama- ja purusiivekekuvien tulkinnassa eri valaistusolosuhteissa. Tutkimuksessa vertailtiin γ 2.2- ja DICOM-kalibroitua perusnäyttöä, tablettia (kolmannen polven Apple iPad®) sekä 6 MegaPikselin (MP) lääketieteelliseen käyttöön tarkoitettua näyttöä. Lisäksi väitöskirjan tarkoituksena oli antaa hammaslääketieteellisten röntgenkuvien katseluun soveltuvia näyttöjä ja käyttöympäristön valaistusta koskevia suosituksia. Kaksi tulkitsijaa arvioi 30 panoraama- ja purusiivekeröntgenkuvaa satunnaisessa järjestyksessä neljältä eri näytöltä kirkkaassa (510 luksia) ja hämärässä (16 luksia) valaistuksessa. Tutkimuksessa arvioitiin sekä korkeakontrastisia anatomisia rakenteita että matalakontrastisia patologisia löydöksiä. Tuloksia verrattiin tutkijoiden väliseen yhteisluentaan. Luotettavuuden arviointiin käytettiin yhdenmukaisuusosuutta sekä painotettua kappaa. Toistettavuuden arvioimiseksi laskettiin kapat toisen alkuperäisten ja uusintaluentojen sekä molempien tulkitsijoiden alkuperäisluentojen välille. Merkitsevyystasoksi määriteltiin p&lt;0,05. DICOM-kalibrointi voi parantaa patologisten löydösten tulkintaa panoraamakuvissa molemmissa valaistusolosuhteissa. DICOM-kalibrointi parantaa selvästi purusiivekekuvien hammaskiille- ja hammasluukarieksen tulkintaa erityisesti kirkkaassa valaistuksessa. Hammaslääkäreiden työskentelytilojen valaistus on yleensä korkeampi kuin tutkimuksessa käytetty, joten näyttöjen käyttöympäristön valaistusta tulisi laskea toimistovalaistusta vastaavaksi. DICOM-kalibroitua perusnäyttöä voidaan suositella käytettäväksi kalliiden medikaalinäyttöjen sijaan. Tablettia tulee sen sijaan käyttää harkiten hammaskuvien tulkintaan.

The theoretical part is focused on lights, notions and calculations in the area of light technology, basic lightning sources and lamps. This work is also about the principle of lightning measuring. The main aim of the work is design of a new artificial lightning system in a High school agriculture in Prerov. At first, the control measuring of existing lightning was done which is mentioned in this work. From the results of control measuring is clear, that existing lighting system in classroom does not suit requirements, which are mentioned in the valid technical norm. Design of a new lightning system meets the requirements in all of the rooms in the building of school. Design of lightning system was done in two variants. The first variant uses lamps with fluorescent tube light sources. The second variant uses lamps with LED light sources. Also is here evaluated financial difficulty of possible installation and comparation of each variants with respect energetic difficulty.

In lighting design, several different variables are measured, such as illuminance. Measuring these values requires different types of measuring instruments, either static measuring instruments or portable measuring instruments. Depending on the make, the same type of measurement can be measured in different ways. A static measuring instrument is usually measured one time at a specific location, while a portable measuring instrument can, for example, measure every minute or every ten minutes for an extended period. With constant research and technological development, the measurement of lighting variables has become more relevant. It is problematic to conduct experiments with a lack of consistent and accurate methods when measuring light. It is important to have the right conditions for a measurement in order for the results to be of good quality. The purpose of this study is to investigate differences between different static and portable measuring instruments used to describe the exposed illuminance and the physical activity. This is done through a pilot study. The pilot study was conducted using an experimental quantitative method with two participants during one day in four different measurement occasions with six different measuring instruments, the measuring instruments being measured in vertical, horizontal and flexible positions. The analysis showed that the results largely depended on whether a static or portable measuring instrument was used. The results also showed that depending on what position the measuring instruments measure from, the results vary. Based on the results, the conclusion is that the closer to eye level one can get, the more relevant the results are. For further research, all the measuring instruments used in the study should be calibrated prior to implementation. For example, it is important to examine the sensitivity of the measuring instruments when measuring indoors and outdoors. More participants, more measurements and more contexts would have been preferable for further research.

Humans are less exposed to natural light during the day and less to darkness at night. Good daylighting provides visual comfort for performing tasks but also influences non-visual comfort. According to various studies, good daylight conditions can influence human physiology and behaviour, like sleep, alertness, mood and cognitive functions. Having good daylight conditions in our homes or student homes can be challenging, even more in Nordic countries. This research focuses on daylight in student dorms, located in Sweden. The influence of orientations and seasonality on daylight qualities is researched by using a survey with subjective evaluations and computer-simulated results. The survey and computer simulations show slight differences between the orientations for the existing situations in the student dorms. In summer and spring, daylight generally has more qualities than in winter and autumn, in some cases, glare can cause discomfort. Larger window dimensions result in more daylight entering future student homes. This improves the daylight conditions in winter and autumn, but east, south and west-facing rooms would benefit from shading to avoid potential glare. The amount of sky present in the outdoor view strongly influences the daylight qualities of a room.

The rise of rock climbing is a global phenomenon. Seven out of ten bouldering gyms opened during this decade in Stockholm. With the increasing sports climbing population, the lighting condition of sports facilities should be a concern, especially since electricity demand growth in buildings has been remarkably rapid. However, not much research has been conducted regarding investigating the effect of artificial lighting on indoor bouldering users' experiences. This thesis investigates a balance between addressing sustainable development goals number 7.3 and maintaining users' experiences while exercising, taking Klätterverket Gasverket as a case study. Different research methods have been used to provide a pilot study to be explored by others, including literature review, semi-structured interviews, and empirical study.  This research has shown that it is hard to draw conclusions regarding the perceived qualities of light. The qualitative and quantitative results conclude that we can decrease electrical consumption in a situation that has sufficient daylight without sacrificing climbers’ experience.  Adjusting the distance between the luminaire and climbing wall can slightly improve the average illuminance level and user experience.