150 research outputs found

    The computerized remote control system for a programmable thermostat

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    Бакалаврська робота складається з чотирьох розділів. Перший розділ описує Аналіз Wi-Fi термостата, його підключення за допомогою BLYNK. У другому розділі описано процес проектування Wi-Fi термостата та обґрунтування апаратного та програмного забезпечення. У третьому розділі виконується впровадження програмного забезпечення та тестування Wi-Fi термостата У четвертому розділі викладено питання безпеки життєдіяльності та основи охорони праці.The bachelor's thesis consists of four sections. The first section describes the Analysis of the Wi-Fi thermostat, it connection using BLYNK. The second section describes the process of designing Wifi thermostat and the justification of the hardware and software. The third section performs software implementation and testing of a Wifi thermostat The fourth section describes the issues of life safety and the basics of labor protection.INTRODUCTION 8 CHAPTER 1 ANALYSIS OF TECHNICAL TASK 9 1.1 Analysis of the Wi-Fi Thermostat 9 1.2 Analysis of the common WiFi thermostat 10 1.3 Overview of the connection via BLYNK, as the main way of communication between the user and the system 12 CHAPTER 2 PROJECT PART 14 2.1 Development of the generalized structure of the computer system 14 2.2 Description of electrical schematic 16 2.3 Description of connection schematic 19 2.4 Justification of the choice of hardware of the Wi-Fi thermostat 21 2.4.1 Wi-Fi board NodeMCU CP2102 ESP8266 21 2.4.2 DHT22 temperature/humidity sensor 23 2.4.3 MH-Z19 CO2 sensor 24 2.4.4 DS3231 real-time clock 26 2.4.5 Blue graphic display 0.96" I2C OLED LCD 28 2.4.6 Transmitter 433MHz 30 2.4.7 Arduino Pro Mini 5V 31 2.4.8 Receiver 433MHz 33 2.4.9 2-channel relay 35 2.4.10 HLK-PM01 adaptor 36 2.5 Justification of the choice of software of the WIFI thermostat 37 2.6 Flowchart for WIFI thermostat 38 CHAPTER 3 PRACTICAL PART 42 3.1 Problems with modern thermostat 42 3.2Powering of the Wi-Fi Thermostat 43 3.3 Placement of DHT22 45 3.4 Alternate for DHT22 46 3.5 Power Supply for Analyser 47 3.6 Power Supply to Contactor Device 48 3.7 Code for contractor 50 3.8 Wi-Fi connection 51 3.9 System testing 54 3.10 Future Improvement 55 CHAPTER 4 SAFETY OF LIVELIHOOD ACTIVITIES, BASIS OF LABOR PROTECTION 59 4.1 Safe Methods using the device 59 4.2 Basic of labor Protection 61 CONCLUSIONS 65 REFERENCES 67 APPENDIX A Program code 6

    The micro-LED roadmap: status quo and prospects

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    Micro light-emitting diode (micro-LED) will play an important role in the future generation of smart displays. They are found very attractive in many applications, such as maskless lithography, biosensor, augmented reality (AR)/mixed reality etc, at the same time. A monitor that can fulfill saturated color rendering, high display resolution, and fast response time is highly desirable, and the micro-LED-based technology could be our best chance to meet these requirements. At present, semiconductor-based red, green and blue micro-LED chips and color-conversion enhanced micro-LEDs are the major contenders for full-color high-resolution displays. Both technologies need revolutionary ways to perfect the material qualities, fabricate the device, and assemble the individual parts into a system. In this roadmap, we will highlight the current status and challenges of micro-LED-related issues and discuss the possible advances in science and technology that can stand up to the challenges. The innovation in epitaxy, such as the tunnel junction, the direct epitaxy and nitride-based quantum wells for red and ultraviolet, can provide critical solutions to the micro-LED performance in various aspects. The quantum scale structure, like nanowires or nanorods, can be crucial for the scaling of the devices. Meanwhile, the color conversion method, which uses colloidal quantum dot as the active material, can provide a hassle-free way to assemble a large micro-LED array and emphasis the full-color demonstration via colloidal quantum dot. These quantum dots can be patterned by porous structure, inkjet, or photo-sensitive resin. In addition to the micro-LED devices, the peripheral components or technologies are equally important. Microchip transfer and repair, heterogeneous integration with the electronics, and the novel 2D material cannot be ignored, or the overall display module will be very power-consuming. The AR is one of the potential customers for micro-LED displays, and the user experience so far is limited due to the lack of a truly qualified display. Our analysis showed the micro-LED is on the way to addressing and solving the current problems, such as high loss optical coupling and narrow field of view. All these efforts are channeled to achieve an efficient display with all ideal qualities that meet our most stringent viewing requirements, and we expect it to become an indispensable part of our daily life

    Use of digital displays and ocular surface alterations

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    Aunque nuestra comprensión de los efectos del uso de dispositivos electrónicos sobre la superficie ocular ha aumentado considerablemente desde el inicio de siglo, varias preguntas importantes siguen sin respuesta. Asimismo, los avances tecnológicos y la aparición de nuevas formas de dispositivos digitales hacen necesaria una investigación continua. Esta tesis doctoral presenta un total de 12 estudios independientes los cuales constituyen los pilares de este trabajo (Capítulos 4-15). En primer lugar, el Capítulo 4 tuvo como objetivo evaluar la asociación entre los factores de riesgo de la enfermedad de ojo seco (EOS) y el síndrome visual informático (SVI). Se llevó a cabo una encuesta online anónima en 851 estudiantes universitarios. Los participantes se clasificaron en dos grupos, en función de si padecían SVI (n = 628) o no (n = 222). Los resultados de este capítulo revelaron que varios factores de riesgo y condiciones de salud relacionados con el ojo seco están asociados con el SVI, por lo que las preguntas relacionadas con los factores de riesgo de la EOS pueden ser especialmente relevantes en pacientes que usan dispositivos electrónicos por períodos prolongados. Las anomalías del parpadeo constituyen uno de los principales mecanismos causantes de las alteraciones de la superficie ocular asociadas al SVI. Así pues, el objetivo del Capítulo 5 fue evaluar las diferencias en la cinemática del parpadeo durante la lectura con diferentes dispositivos electrónicos y una condición control sin dispositivo. Treinta y dos sujetos jóvenes fueron incluidos en este estudio. Se grabó el parpadeo de los participantes mientras leían en un ordenador portátil, una tableta, un libro electrónico (e-book), un teléfono móvil y durante una tarea control sin dispositivo. A juzgar por los resultados, la cinemática de parpadeo varía considerablemente entre los dispositivos y con respecto a una tarea de baja demanda cognitiva sin dispositivo. Estas diferencias probablemente se deban a la diferente forma en que se posicionan y usan las pantallas y a la demanda cognitiva de la tarea. En la actualidad existen diferentes tipos de dispositivos electrónicos y las diferencias en su naturaleza y en la forma en que se utilizan pueden condicionar su impacto sobre la superficie ocular. Teniendo en cuenta los resultados del Capítulo 5, el Capítulo 6 tuvo como objetivo comparar el impacto de dispositivos anteriores sobre la superficie ocular y la película lagrimal de 31 individuos jóvenes. El impacto más bajo se obtuvo con el teléfono móvil y el e-book, probablemente debido a un ángulo de mirada más bajo asociado con el uso del teléfono móvil y a las propiedades ópticas mejoradas del e-book. La instilación de lágrima artificial no mostró una mejora estadística en las variables de superficie ocular y película lagrimal para el mismo dispositivo, aunque atenuó los efectos del uso de la pantalla. Por otro lado, la identificación de individuos con predisposición a alteraciones de la superficie ocular con el uso de los dispositivos electrónicos puede proporcionar al especialista una ventaja considerable en el manejo de la condición. El Capítulo 7 tuvo como objetivo identificar qué parámetros de la superficie ocular y la película lagrimal son predictores del impacto del uso del ordenador sobre la superficie ocular. Para ello, se evaluó la superficie ocular de 82 estudiantes universitarios antes y después de leer con un ordenador durante 30 minutos. Los resultados mostraron que los participantes con mayores síntomas de ojo seco tenían más probabilidades de experimentar un mayor aumento de los síntomas con el uso del ordenador, mientras que un tiempo de ruptura lagrimal más largo y un mayor aumento del enrojecimiento conjuntival estaban asociados a una mayor reducción de la estabilidad lagrimal. Hoy en día los especialistas tienen una variedad de estrategias de manejo disponibles para prevenir o reducir los efectos del uso de dispositivos digitales sobre la superficie ocular. El Capítulo 8 tuvo como objetivo evaluar y comparar la efectividad de cuatro estrategias principales de manejo (instilación inicial de lágrima artificial, descanso breve, uso de un filtro de luz azul y control de parpadeo) para prevenir los efectos del uso de pantallas digitales sobre la superficie ocular, en una muestra de 47 individuos jóvenes. Los resultados de este capítulo evidenciaron que la instilación de lágrima artificial y el control del parpadeo son las mejores estrategias de manejo para prevenir los efectos del uso de pantallas digitales sobre la superficie ocular, mientras que el uso de un filtro de luz azul no ofrece beneficios apreciables. El uso de lentes de contacto es ampliamente reconocido como uno de los principales factores de riesgo para la EOS y, en consecuencia, para el SVI. Por ende, el Capítulo 9 tuvo como objetivo evaluar los posibles efectos sumatorios del uso de dispositivos electrónicos (ordenador y teléfono móvil) por periodos cortos y de lentes de contacto sobre la superficie ocular y la película lagrimal en una muestra de 34 adultos jóvenes. Los hallazgos de este capítulo indicaron que el uso de lentes de contacto no tiene efectos sumatorios sobre los signos y síntomas de ojo seco cuando se usan dispositivos digitales por períodos cortos y que la instilación de lágrima artificial es una estrategia eficaz para reducir el impacto del uso de dispositivos electrónicos en usuarios de lentes de contacto. Del mismo modo, el ojo seco se clasifica como el efecto adverso más común de la queratomileusis in situ asistida por láser (LASIK, del inglés laser in-situ keratomileusis), teniendo esta técnica la mayor incidencia y gravedad de EOS posoperatoria de todos los procedimientos queratorefractivos. El objetivo del Capítulo 10 fue evaluar el impacto del uso del ordenador por periodos cortos sobre la superficie ocular en personas intervenidas de LASIK, a fin de determinar si los pacientes post-LASIK tienen un mayor riesgo de ojo seco asociado al uso de dispositivos digitales. Se evaluaron los síntomas de ojo seco y la superficie ocular de 18 individuos jóvenes intervenidos de LASIK miópico y 18 controles, antes y después de realizar una tarea de 30 minutos utilizando un ordenador con y sin instilación inicial de lágrima artificial. En definitiva, el aumento de los síntomas de ojo seco y los síntomas de SVI reportados durante la tarea con el ordenador fueron similares entre ambos grupos de estudio. Los síntomas estuvieron acompañados por un empeoramiento significativo de los signos de ojo seco en el grupo LASIK. Por otro lado, la instilación de lágrima artificial fue eficaz para prevenir el empeoramiento de los signos y síntomas del ojo seco en ambos grupos poblacionales. El objetivo del Capítulo 11 fue evaluar la relación entre los síntomas oculares y la sensibilidad corneal a estímulos mecánicos y fríos en 52 usuarios frecuentes de ordenador, tras haberse reportado que períodos repetidos de estimulación de la superficie ocular por inestabilidad lagrimal pueden alterar la excitabilidad de los receptores corneales y su capacidad de respuesta a estímulos nuevos. Los umbrales de sensibilidad mecánica y al frío de la córnea central se determinaron en un ojo aleatoriamente seleccionado de cada participante utilizando el UNSW LJA (del inglés University of New South Wales Liquid Jet Aesthesiometer). Los usuarios de ordenador sintomáticos mostraron umbrales de sensibilidad al frío más bajos en comparación con los usuarios asintomáticos, lo que sugiere alteraciones en la función sensorial de la córnea en usuarios de ordenador con SVI. Asimismo, mayores síntomas de SVI, particularmente síntomas relacionados con el ojo seco, se asociaron con umbrales de excitación más bajos (hipersensibilidad) de las neuronas corneales a estímulos fríos. Teniendo en cuenta estos hallazgos, el Capítulo 12 tuvo como objetivo evaluar los posibles efectos del uso del ordenador durante periodos cortos sobre la sensibilidad de la córnea y analizar las asociaciones con posibles factores determinantes en una muestra similar de sujetos jóvenes. Las medidas de sensibilidad se tomaron antes y después de trabajar con un ordenador de sobremesa durante 1 hora en una tarea de libre elección. En base a los resultados de este capítulo, el uso del ordenador durante un periodo de una hora no tuvo ningún efecto sobre la sensibilidad de la córnea central a estímulos mecánicos y fríos. Además, los síntomas oculares y las variables demográficas no se asociaron con los cambios en la sensibilidad con el uso del ordenador. Debido al cambio significativo en el índice de refracción del aire a la película lagrimal, las anomalías en la película lagrimal pueden afectar notablemente a la calidad visual. Con esta premisa en mente, el objetivo del Capítulo 13 fue evaluar y comparar exhaustivamente los cambios en la función visual y la calidad óptica y de la película lagrimal en un grupo de trabajadores que usaban el ordenador como herramienta de trabajo (n = 40) y un grupo de trabajadores sin ordenador (n = 40) a lo largo de una jornada laboral normal. Según los resultados de este capítulo, aunque la agudeza visual se mantuvo sin cambios, varios aspectos de la función y la calidad visual disminuyeron durante un día de uso del ordenador. Estos cambios estuvieron acompañados de una mayor sintomatología de ojo seco y alteraciones de la película lagrimal, las cuales probablemente jugaron un papel fundamental. El SVI está muy influenciado por la demanda visual y la duración de la tarea. A los usuarios frecuentes de dispositivos digitales a menudo se les recomienda seguir la regla 20-20-20 (apartar la mirada de la pantalla durante al menos 20 s a un objeto distante situado a una distancia de al menos 20 pies tras 20 minutos de trabajo continuo), aunque con evidencia científica limitada. El objetivo del Capítulo 14 fue evaluar los beneficios visuales de tomar descansos regulares basados en esta popular regla de ergonomía visual. Para ello, se descargó en los ordenadores portátiles de 29 usuarios de ordenador sintomáticos un software informático (eyeblink, https://www.blinkingmatters.com/), modificado por el desarrollador para este estudio, que utilizaba la cámara web del ordenador para evaluar los descansos del usuario, la mirada y el parpadeo, y el cual emitía recordatorios personalizados de descansos basados en la regla 20-20-20. El SVI, la visión binocular y la superficie ocular se evaluaron antes y después de seguir la regla durante dos semanas y una semana tras su interrupción. Los resultados de este capítulo indicaron que la regla 20-20-20 es una estrategia eficaz para reducir los síntomas de SVI y ojo seco, aunque dos semanas no fueron suficientes para mejorar considerablemente la visión binocular o los signos de ojo seco. Por último, teniendo en cuenta los cambios globales en la educación y en los patrones de uso de la tecnología que surgieron tras el brote de coronavirus (COVID-19), el Capítulo 15 tuvo como objetivo evaluar los posibles efectos de cambiar a un formato de educación online sobre los síntomas de ojo seco y los factores de riesgo de la EOS. Para ello se llevó a cabo una encuesta online, transversal y anónima en 812 estudiantes universitarios. En general, asistir a clases online se asoció de forma independiente con tener síntomas de ojo seco. A pesar de una menor prevalencia de factores de riesgo de EOS, un mayor uso del ordenador estuvo detrás de la mayor sequedad ocular reportada por los estudiantes online.Although our understanding of the effects of digital display use on the ocular surface has increased considerably since the turn of the century, several major questions remain unanswered. Likewise, technological advances and the appearance of new forms of digital displays demand continuous research. This thesis presents a total of 12 independent studies that constitute the chapters of this work (Chapters 4-15). In the first place, Chapter 4 aimed to explore the association between digital eye strain (DES) and dry eye-related lifestyle and demographic factors. For this purpose, an anonymous online survey was carried out on 851 university students. Participants were classified into DES (n = 628) or non-DES (n = 222). The results of this chapter revealed that several dry eye-related risk factors and health conditions are associated with DES. Therefore, clinicians should acknowledge the relevance of triaging questions and dry eye disease (DED) risk factors when dealing with patients who view screens for extended periods. Blinking abnormalities make up one of the main DES-inducing mechanisms. Accordingly, the aim of Chapter 5 was to assess the differences in blinking kinematics between reading on different digital displays and a non-device control condition. Thirty-two young individuals were included in this study. The blinks of the participants were recorded while reading on a laptop computer, tablet, electronic reader (e-reader), and smartphone and in a non-device control condition. Judging by the results, blinking kinematics seem to vary considerably between displays and with respect to a non-device, low-demanding control condition. These differences could probably be attributed to differences in the way the displays are set up and used and the cognitive demand of the task at hand. Nowadays, numerous new kinds of digital displays have been developed and the differences in their nature and the ways in which they are set up and used may condition their impact on the ocular surface. Bearing in mind the results of Chapter 5, Chapter 6 aimed to compare the impact of the aforementioned digital displays on the ocular surface and tear film of 31 young individuals. According to the findings of this chapter, the lowest impact was obtained with the smartphone and the e-reader, probably due to a lower gaze angle associated with smartphone use and to the enhanced optical properties of the e-reader. The instillation of artificial tears did not show a statistical improvement in ocular surface and tear film variables for the same device, although it attenuated the effects of display use. On a different note, effective identification of individuals with a predisposition to the disruption of their ocular surface following display use can provide the practitioner with a considerable advantage in managing the condition. Chapter 7 aimed to identify which ocular surface and tear film characteristics are relevant predictors of the impact of computer use on dry eye signs and symptoms. For the purpose, the ocular surface of 82 undergraduate students was assessed at baseline and after they had read on a computer for 30 minutes. According to the results of this chapter, participants with greater dry eye symptoms were more likely to experience a greater increase in symptomatology following computer use, while a longer tear break-up time and a greater increase in conjunctival redness with computer use were associated with a greater reduction in tear stability. Nowadays, clinicians have a range of management strategies available to reduce or prevent the effects of digital display use on the ocular surface. Chapter 8 aimed to assess and compare the effectiveness of four main management strategies (instillation of artificial tears, taking a brief break, using a blue light screen filter, and blink control) for preventing the short-term effects of digital display use on dry eyes, in a sample of 47 young individuals. The results of this chapter showed that the instillation of artificial tears and blink control were the best management strategies for preventing short-term effects of digital display use on dry eyes, while using a blue light filter did not offer any benefits. Contact lens (CL) wear is widely recognised as one of the main risk factors for DED and consequently for DES. Accordingly, Chapter 9 aimed to evaluate the potential additive effects of short-term display use (computer and smartphone) and CL wear, in addition to the benefits of artificial tear instillation, on the ocular surface and tear film in a sample of 34 young volunteers. The findings of this chapter showed that CL wear has no additive effects on signs and symptoms of dry eye when using digital devices for short periods and that the instillation of artificial tears is an effective strategy for reducing the impact of display use in CL wearers. Similarly, dry eye is categorized as the most common adverse effect of laser in situ keratomileusis (LASIK) surgery, with this technique having the highest incidence and severity of postoperative DED of all kerato-refractive procedures. The aim of Chapter 10 was to assess the impact of short-term computer use on the ocular surface of individuals after LASIK in order to determine whether post-LASIK patients are at an increased risk of digital display-induced dry eye. The dry eye symptoms and ocular surface of 18 post-myopic LASIK, young individuals and 18 controls were evaluated before and after performing a 30-minute task on a computer with and without initial instillation of artificial tears. Overall, the increase in symptoms of dry eye and the symptoms of DES reported during the computer task were comparable between both study groups. Symptoms were accompanied by a significant worsening of dry eye signs in the LASIK group. In parallel, the instillation of artificial tears was effective in preventing the worsening of dry eye signs and symptoms in all cases. Repeated periods of ocular surface stimulation by tear film instability may alter the excitability of corneal receptors and their responsiveness to new stimuli. Accordingly, the aim of Chapter 11 was to evaluate the relationship between ocular symptoms and corneal sensitivity to mechanical and cold stimuli in 52 frequent computer users. Mechanical and cold sensation thresholds were determined at the central cornea of the randomly selected eye of each participant using the University of New South Wales Liquid Jet Aesthesiometer (UNSW LJA, UNSW, Sydney, Australia). Symptomatic computer users exhibited lower cold sensation thresholds compared to asymptomatic users, which suggests alterations in the corneal sensory function among computer users with DES. Likewise, greater symptoms of DES, particularly dry eye related symptoms, were associated with lowered excitation thresholds (hypersensitivity) of the corneal neurons to corneal cooling. Considering these findings, Chapter 12 aimed to evaluate the potential effects of short-term computer use on the sensitivity of the cornea to various stimuli and analyse associations with possible determinants in a similar sample of subjects. Sensitivity measurements were taken before and after working on a desktop computer for 1 hour in a freely chosen task. The results of this chapter indicate that short-term computer use had no effect on the sensitivity of the central cornea to mechanical and cold stimuli. Additionally, ocular symptoms and demographic variables were not associated with the changes in sensitivity following computer use. Due to the significant refractive index change from air to tear film, abnormalities to the tear film can impact visual quality in a significant way. Based on this premise, the aim of Chapter 13 was to thoroughly assess and compare the changes in visual function and optical and tear film quality in a group of computer workers (n = 40) and a group of non-computer workers (n = 40) throughout a normal working day. According to the results of this chapter, while visual acuity remained unchanged, several aspects of visual function and quality of vision declined over a day of intense computer use. DES is highly influenced by the visual demand and the duration of a given task. Based on this principle, frequent screen users are often advised to follow the 20-20-20 rule (look away from the screen for at least 20 s to a distant scene at least 20 feet away after every 20 minutes of continuous work), although with limited evidence. Accordingly, the aim of Chapter 14 was to evaluate the visual benefits of taking regular breaks based on this popular rule of visual ergonomics. To test the study hypothesis, bespoke computer software (eyeblink, https://www.blinkingmatters.com/), modified for the study by the developer, which employs the laptop webcam to assess user breaks, eye gaze and blinking, and which emits personalized reminders of breaks based on the 20-20-20 rule, was downloaded onto the laptops of 29 symptomatic computer users. DES, binocular vision and dry eye were assessed before and after two weeks of using the reminders and one week after the discontinuation of the strategy. The results of this chapter indicate that the 20-20-20 rule is an effective strategy for reducing DES and dry eye symptoms, although 2 weeks was not enough to considerably improve binocular vision or dry eye signs. Finally, considering the global changes in education and technology use patterns following the coronavirus (COVID-19) outbreak, the last study presented in this work, and described in detail in Chapter 15, aimed to assess the potential effects of switching to an online lecture format on dry eye symptoms and DED risk factors. For this purpose, an anonymous cross-sectional online survey was carried out on 812 university students. Largely, attending online lectures was independently associated with having dry eye symptoms. Despite a lower prevalence of DED risk factors, higher computer use is probably the reason behind the greater ocular dryness reported by online students

    Low-Power and High-Performance Drivers for OLEDoS Microdisplays

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    The rapid growth of the microdisplay market, driven by the demand for smartwatches, head-mounted displays in Virtual Reality (VR) and Augmented Reality (AR), and other portable devices, has presented a need to enhance their energy efficiency. This thesis focuses on reducing the power and energy consumption of microdisplays while maintaining display luminance, and image quality; and enhancing key features such as resolution, refresh rate, and color depth. First, a novel driving method and pixel circuit are proposed that reduces the number of subframes in a digitally-driven display. The dual-driver method offers flexibility in different design modes, allowing for the enhancement of various display characteristics. In the low-power mode, the operating frequency is reduced, resulting in decreased dynamic power consumption by the drivers. Experimental results on a proof-of-concept array fabricated using TSMC 65 nm technology demonstrate a significant 39% reduction in power consumption compared to a conventional array. Furthermore, designing the display in other modes yields remarkable improvements, with up to 8.5 times enhancement in refresh rate or resolution. In addition, the high color depth mode presents an opportunity to increase color depth from 8 bits to 14 bits, enhancing the visual experience. Additionally, this thesis investigates power reduction techniques specific to row drivers in microdisplays. Circuit techniques are proposed to recycle energy in the row driver, thereby reducing dynamic power consumption. Measurement results on proof-of-concept arrays implemented in TSMC 65 nm technology reveal substantial reductions of up to 30% in the power consumption of the row driver using different energy recycling techniques. Applying these techniques led to a significant reduction in the dynamic power consumption of the row driver. For instance, employing the direct energy restoration technique resulted in a remarkable decrease of over 45% in the dynamic power consumption of the row driver. Finally, a digital data driver with a data energy recycling feature is presented to further reduce the dynamic power consumption of microdisplays. Measurement results obtained from a proof-of-concept array fabricated using TSMC 65 nm technology demonstrate an average power consumption reduction of 16% in the display’s data driver when subjected to randomly generated test images. This thesis addresses the pressing need for energy-efficient microdisplays, offering innovative driving methods, pixel circuit design, and dynamic power reduction techniques. The proposed solutions provide significant power savings while preserving display quality and enabling enhancements in resolution, refresh rate, and color depth, contributing to extended battery life and improved user experience in portable electronic systems

    Texture and Colour in Image Analysis

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    Research in colour and texture has experienced major changes in the last few years. This book presents some recent advances in the field, specifically in the theory and applications of colour texture analysis. This volume also features benchmarks, comparative evaluations and reviews

    Interference Suppression in Massive MIMO VLC Systems

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    The focus of this dissertation is on the development and evaluation of methods and principles to mitigate interference in multiuser visible light communication (VLC) systems using several transmitters. All components of such a massive multiple-input multiple-output (MIMO) system are considered and transformed into a communication system model, while also paying particular attention to the hardware requirements of different modulation schemes. By analyzing all steps in the communication process, the inter-channel interference between users is identified as the most critical aspect. Several methods of suppressing this kind of interference, i.e. to split the MIMO channel into parallel single channels, are discussed, and a novel active LCD-based interference suppression principle at the receiver side is introduced as main aspect of this work. This technique enables a dynamic adaption of the physical channel: compared to solely software-based or static approaches, the LCD interference suppression filter achieves adaptive channel separation without altering the characteristics of the transmitter lights. This is especially advantageous in dual-use scenarios with illumination requirements. Additionally, external interferers, like natural light or transmitter light sources of neighboring cells in a multicell setting, can also be suppressed without requiring any control over them. Each user's LCD filter is placed in front of the corresponding photodetector and configured in such a way that only light from desired transmitters can reach the detector by setting only the appropriate pixels to transparent, while light from unwanted transmitters remains blocked. The effectiveness of this method is tested and benchmarked against zero-forcing (ZF) precoding in different scenarios and applications by numerical simulations and also verified experimentally in a large MIMO VLC testbed created specifically for this purpose

    Lisímetro inteligente com monitorização da cultura e ambiente: Uma aproximação IoT

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    Adotando uma abordagem IoT apresentamos um modelo de lisímetro inteligente, melhorado com análise de pragas e o estado da cultura. Além da obtenção do balanço tradicional de evaporação-transpiração, o lisímetro mede parâmetros adicionais tais como a temperatura e humidade do solo, a diferentes profundidades; temperatura e humidade do ar; exposição à luz solar (visível e infravermelho). Além disso, o sistema faz a captura imagens de alta resolução da cultura alvo. Estas imagens são processadas localmente, para redução de dados que são armazenados posteriormente numa plataforma remota. O objetivo principal é a monitorização e com vista ao aumento da produtividade global da cultura. Este lisímetro também fornece dados para um sistema global de monitorização de recursos hídricos que integra informações de várias fontes: outros lisímetros, estações meteorológicas, sistemas de monitorização da qualidade da água, etc.. O resultado deste trabalho culminou no desenvolvimento e teste de um protótipo funcional

    Advances in Image Processing, Analysis and Recognition Technology

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    For many decades, researchers have been trying to make computers’ analysis of images as effective as the system of human vision is. For this purpose, many algorithms and systems have previously been created. The whole process covers various stages, including image processing, representation and recognition. The results of this work can be applied to many computer-assisted areas of everyday life. They improve particular activities and provide handy tools, which are sometimes only for entertainment, but quite often, they significantly increase our safety. In fact, the practical implementation of image processing algorithms is particularly wide. Moreover, the rapid growth of computational complexity and computer efficiency has allowed for the development of more sophisticated and effective algorithms and tools. Although significant progress has been made so far, many issues still remain, resulting in the need for the development of novel approaches
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