Dependence of the integral characteristics of a nematic light modulator on the physical parameters of a liquid crystal

In the present work, the effect of physical constants of an LC material on the integral characteristics of a modulator operating in a waveguide mode in an LC structure with a twist angle of 270 and antisymmetric boundary conditions in the working cell was studied using the method of computer simulation. It is shown that, under antisymmetric boundary conditions, the small value of the total response time of the LC modulator is due to the absence of a “backflow” in the LC cell and the role of only half of the LC working gap thickness in the dynamics of switching between two states in such a device. In addition, it was found that in order to simultaneously achieve high contrast ratios and a short total response time of the device, it is necessary to choose an LC material with a high value of its dielectric anisotropy. In this case, there is an optimal set of elasticity constants for the LC material, which simultaneously realizes a high contrast ratio and a short total response time of the modulator.

Performance analysis of time and cost efficient data pre-fetching in mobile cloud computing

Recently, many methods and algorithms have been proposed in pre-fetching area. However, pre-fetching integrated with workload scheduling approaches have not been investigated as much. Initially, this thesis reviews the principles of the existing pre-fetching strategies considering latency and cost factor as primary objectives. Later, it focuses on an integrated workload scheduling and pre-fetching model to enhance the performance of response time and minimize the cost. Furthermore, response time and cost problems are formulated and to overcome the total response time and cost problems a heuristic approach is proposed. Integrated model is tested for wide range of variables and, the effects of various parameters such as processing speed and pre-fetcher’s utilization are analysed and compared. Finally, based on the results integrated pre-fetching and workload scheduling model outperforms either of them, individually. Thus, this thesis can contribute to the the new solutions in this area.

Performance analysis of time and cost efficient data pre-fetching in mobile cloud computing

Recently, many methods and algorithms have been proposed in pre-fetching area. However, pre-fetching integrated with workload scheduling approaches have not been investigated as much. Initially, this thesis reviews the principles of the existing pre-fetching strategies considering latency and cost factor as primary objectives. Later, it focuses on an integrated workload scheduling and pre-fetching model to enhance the performance of response time and minimize the cost. Furthermore, response time and cost problems are formulated and to overcome the total response time and cost problems a heuristic approach is proposed. Integrated model is tested for wide range of variables and, the effects of various parameters such as processing speed and pre-fetcher’s utilization are analysed and compared. Finally, based on the results integrated pre-fetching and workload scheduling model outperforms either of them, individually. Thus, this thesis can contribute to the the new solutions in this area.

Serviço de atendimento móvel de urgência do Rio Grande do Sul

Objetivo: analisar os atendimentos realizados na Central de Regulação de Urgência/SAMU do Estado do Rio Grande do Sul no período de 2016 e 2017. Metodologia: estudo observacional, descritivo e retrospectivo com abordagem quantitativa. Foram coletados os dados sobre perfil do usuário, dia da semana, classificação de risco, tipo do agravo, tempo médio de atendimento às solicitações, quantitativo de desistência da solicitação e número de chamados não regulados por falta de equipes ou veículos. Resultados: o número de solicitações por motivos clínicos foi 53.8%, destes 51,6% foram média gravidade. A prevalência foi do sexo masculino e idade entre 18 e 29 anos. Em 84,7% dos chamados solicitou-se suporte básico. O tempo resposta total foi entre 30 minutos e 1 hora, maior que o recomendado de acordo com a média nacional, seja nas as zonas urbanas ou rurais. Conclusão: este serviço necessita reduzir o tempo resposta de atendimento das solicitações.Palavras-chave: SAMU; Indicadores; Central de Regulação Estadual; Serviços Médicos de Emergência; Administração de Serviços de Saúde. Objective: to analyze the attendances performed at the Emergency Regulation Center / SAMU of the State of Rio Grande do Sul in 2016 and 2017, focusing in response time. Methodology: observational, descriptive and retrospective study with quantitative approach. Data were collected on user profile, day of the week, risk classification, type of grievance, average time to respond to requests, amount of withdrawal and number of calls not regulated due to lack of teams or vehicles. Results: The number of requests for clinical reasons was 53.8%, of these 51.6% were medium severity. The prevalence was male and aged between 18 and 29 years. In 84.7% of the calls, basic support was requested. The total response time was between 30 minutes and 1 hour, longer than recommended according to the national average, whether in urban or rural areas. Conclusion: After analyzing the calls, it is clear that the worst problem with the calls is the response time, and it is necessary to decrease the same of the requests.Key-words: SAMU; Indicators; Central of State Regulation; Emergency Medical Services; Health Services Administration. Objetivo: analizar las asistencias realizadas en el Centro de Regulación de Emergencias / SAMU del Estado de Rio Grande do Sul en 2016 y 2017, centrándose en el tiempo de respuesta. Metodología: estudio observacional, descriptivo y retrospectivo con enfoque cuantitativo. Se recopilaron datos sobre el perfil del usuario, el día de la semana, la clasificación de riesgos, el tipo de queja, el tiempo promedio para responder a las solicitudes, la cantidad de retiros y la cantidad de llamadas no reguladas debido a la falta de equipos o vehículos. Resultados: El número de solicitudes por razones clínicas fue del 53.8%, de estas 51.6% fueron de gravedad media. La prevalencia fue masculina y de edades comprendidas entre 18 y 29 años. En el 84.7% de las llamadas, se solicitó soporte básico. El tiempo de respuesta total fue de entre 30 minutos y 1 hora, más de lo recomendado según el promedio nacional, ya sea en áreas urbanas o rurales. Conclusión: Después de analizar las llamadas, está claro que el peor problema con las llamadas es el tiempo de respuesta, y es necesario disminuir las mismas solicitudes.Palabras clave: SAMU; Indicadores; Central de Regulación Estatal; Servicios Médicos de Urgencia; Administración de los Servicios de Salud.

A Hybrid Multiple Parallel Queuing Model to Enhance QoS in Cloud Computing

Among the different QoS metrics and parameters considered in cloud computing are the waiting time of cloud tasks, execution time of tasks in VM's, and the utilization rate of servers. The proposed model was developed to overcome some of the pitfalls in the existing systems among which are sub-optimal markdown in the queue length, waiting time, response time, and server utilization rate. The proposed model contemplates on the enhancement of these metrics using a Hybrid Multiple Parallel Queuing approach with a joint implementation of M/M/1: ∞ and M/M/s: N/FCFS to achieve the desired objectives. A neoteric set of mathematical equations have been formulated to validate the efficiency and performance of the hybrid queuing model. The results have been validated with reference to the workload traces of Bit Brains infrastructure provider. The results obtained indicate the significant reduction in the queue length by 60.93 percent, waiting time in the queue by 73.85 percent, and total response time by 97.51%.

Ultrafast electrical switching of nanostructured metadevice with dual-frequency liquid crystal

Shortening of switching times of various soft-matter-based tunable metamaterials is one of the key challenges to improve the functionality of modern active devices. Here we show an effective strategy in the evolution of soft-matter-based tunable metamaterials that makes possible acceleration of both on and off switching processes by using a dual-frequency liquid crystal mixture. The frequency-convertible dielectric anisotropy of the dual-frequency mixture enabled us to create a fast-response in-plane switching metasurface at the nanoscale, which could be tuned by an electrical signal with different frequencies. The results clearly show that the resonance of the metamaterial can be continuously and reversibly controlled within a wavelength range of 100 nm as the applied frequency is inverted between 1 kHz and 40 kHz, with a total response time (τ = τON + τOFF) of 1.89 ms. Furthermore, experimental characteristics of the hybrid metamaterial are in great agreement with numerical calculations, which allow us to anticipate active epsilon-near-zero behavior of the metadevice. This work indicates the future development direction of liquid-crystal-based active plasmonic systems.

Effects of Touch Screen Interface Parameters on User Task Performance

The influence of different touch screen interface design features on user experience and operators’ task performance was investigated in the current study. Eight participants performed different tasks on a touchscreen monitor with varied interface settings while their performance was recorded and compared. Results demonstrated that an oversized desktop touchscreen monitor could generate negative impacts on users’ performance. Smaller icon size also decreased task performance by increasing total response time. In addition, icon color also influenced users’ performance. Results of the current study provide useful data for new approaches to design improvements which will enhance human performance and users’ experience.