870 resultados para 240501 Acoustics and Acoustical Devices


Relevância:

100.00% 100.00%

Publicador:

Resumo:

O uso de dispositivos móveis está a ganhar cada vez mais espaço dentro das organizações. O aumento do consumo de material informático por parte dos consumidores está a levar a que os mesmos comecem a tentar utilizar os seus dispositivos móveis1 Notebooks, Tablets e Smartphones no interior das organizações. Este tipo de comportamento, levou ao aparecimento de uma nova tendência – o Bring Your Own Device (BYOD), a utilização de dispositivos móveis para fins laborais, levanta várias e sérias questões de segurança aos departamentos de TI das organizações, fazendo com que as organizações necessitem de definir novas políticas de segurança para que a sua informação e os seus dados se mantenham seguros. O trabalho adiante desenvolvido pretende mostrar de que forma as organizações veem esta mudança de paradigma, em que os próprios colaboradores utilizam os seus dispositivos móveis como ferramenta de trabalho na organização. Por outro lado analisar os modelos de segurança que se podem associar ao BYOD e aos dispositivos móveis para permitir uma maior segurança dos dados e informação que circula entre a organização e o dispositivo móvel.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Communities, neighborhoods, and other environments are currently immersed in a series of situations and problems that have favored the deterioration of social, cultural and spiritual values, which are essential for harmony with oneself, others, and the environment. Stereotypes have captured minds and settings have been reduced to indoor spaces, hemmed in by security bars and protective devices.  Peace, fraternity and happiness are diminishing.  It is at this point that the social, spiritual and professional work of specialists in the recreational field contributes to rescue and restructure society. Traditional games and singing games are then the tools used to facilitate relationships, contribute to the learning process, and exhibit skills.  They are fundamental in a person’s life since they are a social and cultural expression of how humans have adapted to their environment (Maestro, 2005).  They do not take ethnicity, age, sex or social conditions into consideration.  Traditional games are also a way of promoting health, improving motor, cognitive and emotional skills and a means of encouraging creativity and imagination and developing a sense of rhythm.  Their goal is to attain a state of personal well-being.  They are a way to release tension and accumulated energy and to get away from the daily routine.  They represent a bridge to learn about oneself, the environment, values, habits, and traditions. In this document, readers will learn how traditional games are transmitted, what their characteristics are, why they are an important tool in today’s society, how they are prepared, and how they can be revived and preserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The authors discuss and demonstrate the growth of InN surface quantum dots on a high-In-content In0.73Ga0.27N layer, directly on a Si(111) substrate by plasma-assisted molecular beam epitaxy. Atomic force microscopy and transmission electron microscopy reveal uniformly distributed quantum dots with diameters of 10–40 nm, heights of 2–4 nm, and a relatively low density of ∼7 × 109 cm−2. A thin InN wetting layer below the quantum dots proves the Stranski-Krastanov growth mode. Near-field scanning optical microscopy shows distinct and spatially well localized near-infrared emission from single surface quantum dots. This holds promise for future telecommunication and sensing devices.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Field effect devices have been formed in which the active layer is a thin film of poly(3-methylthiophene) grown electrochemically onto preformed source and drain electrodes. Although a field effect is present after electrochemical undoping, stable device characteristics with a high modulation ratio are obtained only after vacuum annealing at an elevated temperature, and only then if the devices are held in vacuo. The polymer is shown to be p type and the devices operate in accumulation only. The hole mobility in devices thermally annealed under vacuum is around 10 -3 cm 2 V -1 s -1. On exposure to ambient laboratory air, the device conductance increases by several orders of magnitude. This increase may be reversed by subjecting the device to a further high-temperature anneal under vacuum. Subsidiary experiments show that these effects are caused by the reversible doping of the polymer by gaseous oxygen.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Personal electronic devices, such as cell phones and tablets, continue to decrease in size while the number of features and add-ons keep increasing. One particular feature of great interest is an integrated projector system. Laser pico-projectors have been considered, but the technology has not been developed enough to warrant integration. With new advancements in diode technology and MEMS devices, laser-based projection is currently being advanced for pico-projectors. A primary problem encountered when using a pico-projector is coherent interference known as speckle. Laser speckle can lead to eye irritation and headaches after prolonged viewing. Diffractive optical elements known as diffusers have been examined as a means to lower speckle contrast. Diffusers are often rotated to achieve temporal averaging of the spatial phase pattern provided by diffuser surface. While diffusers are unable to completely eliminate speckle, they can be utilized to decrease the resultant contrast to provide a more visually acceptable image. This dissertation measures the reduction in speckle contrast achievable through the use of diffractive diffusers. A theoretical Fourier optics model is used to provide the diffuser’s stationary and in-motion performance in terms of the resultant contrast level. Contrast measurements of two diffractive diffusers are calculated theoretically and compared with experimental results. In addition, a novel binary diffuser design based on Hadamard matrices will be presented. Using two static in-line Hadamard diffusers eliminates the need for rotation or vibration of the diffuser for temporal averaging. Two Hadamard diffusers were fabricated and contrast values were subsequently measured, showing good agreement with theory and simulated values. Monochromatic speckle contrast values of 0.40 were achieved using the Hadamard diffusers. Finally, color laser projection devices require the use of red, green, and blue laser sources; therefore, using a monochromatic diffractive diffuser may not optimal for color speckle contrast reduction. A simulation of the Hadamard diffusers is conducted to determine the optimum spacing between the two diffusers for polychromatic speckle reduction. Experimental measured results are presented using the optimal spacing of Hadamard diffusers for RGB color speckle reduction, showing 60% reduction in contrast.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Advancements in the micro-and nano-scale fabrication techniques have opened up new avenues for the development of portable, scalable and easier-to-use biosensors. Over the last few years, electrodes made of carbon have been widely used as sensing units in biosensors due to their attractive physiochemical properties. The aim of this research is to investigate different strategies to develop functionalized high surface carbon micro/nano-structures for electrochemical and biosensing devices. High aspect ratio three-dimensional carbon microarrays were fabricated via carbon microelectromechanical systems (C-MEMS) technique, which is based on pyrolyzing pre-patterned organic photoresist polymers. To further increase the surface area of the carbon microstructures, surface porosity was introduced by two strategies, i.e. (i) using F127 as porogen and (ii) oxygen reactive ion etch (RIE) treatment. Electrochemical characterization showed that porous carbon thin film electrodes prepared by using F127 as porogen had an effective surface area (Aeff 185%) compared to the conventional carbon electrode. To achieve enhanced electrochemical sensitivity for C-MEMS based functional devices, graphene was conformally coated onto high aspect ratio three-dimensional (3D) carbon micropillar arrays using electrostatic spray deposition (ESD) technique. The amperometric response of graphene/carbon micropillar electrode arrays exhibited higher electrochemical activity, improved charge transfer and a linear response towards H2O2 detection between 250μM to 5.5mM. Furthermore, carbon structures with dimensions from 50 nano-to micrometer level have been fabricated by pyrolyzing photo-nanoimprint lithography patterned organic resist polymer. Microstructure, elemental composition and resistivity characterization of the carbon nanostructures produced by this process were very similar to conventional photoresist derived carbon. Surface functionalization of the carbon nanostructures was performed using direct amination technique. Considering the need for requisite functional groups to covalently attach bioreceptors on the carbon surface for biomolecule detection, different oxidation techniques were compared to study the types of carbon–oxygen groups formed on the surface and their percentages with respect to different oxidation pretreatment times. Finally, a label-free detection strategy using signaling aptamer/protein binding complex for platelet-derived growth factor oncoprotein detection on functionalized three-dimensional carbon microarrays platform was demonstrated. The sensor showed near linear relationship between the relative fluorescence difference and protein concentration even in the sub-nanomolar range with an excellent detection limit of 5 pmol.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This writing forms part of a portfolio of works which gathers together notations and recordings made between 2012 and 2015. The writing divides into four chapters. The first chapter undertakes an examination of abstraction. From the proposition obtained therein, that it is possible to extend within abstraction beyond a correspondence between its terms and concrete manifestations, I ask in what way abstraction may be considered to function therefrom. The second chapter performs an analysis of radical music notations from the nineteenth, twentieth, and twenty-first centuries. The central analysis identifies what is essentially an evolution of what I call ''figuration'' throughout three non-chronological phases of Christian Wolff's notations. The chapter closes by questioning what form of understanding might yet be pursued in respect of this work given (a) its nature, and (b) the nature of our inquiry. The third chapter reflects on some of the philosophical problematics raised in the preceding chapters, at the same time as it prepares for those that follow in the final chapter. The final chapter is a record of the development of my thought appertaining to my compositional work. It sets out two case studies (prepared piano and postcard notations) before proceeding to a selected set of commentaries. Finally, the notion of the functioning of written and acoustical ''marks'' developed in the preceding commentaries is generalised as I develop an aesthetics of scriptural experience.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

People with intellectual disability are living longer, which creates new demands for the support and care of this target group. Participation and autonomy at all ages, regardless of functional capacity, are cited in legislation and among the key objectives of disability policy. As a group, older people with intellectual disability have previously been almost invisible in both policy documents and research. Information regarding this group is thus limited, and more systematic knowledge is needed about older people with intellectual disability, their daily lives, and especially their opportunities for autonomy. The purpose of this thesis is to learn more about the role of influence and autonomy in everyday life from the perspective of older people with intellectual disability living in group homes. This will be achieved by studying situations in which opportunities and obstacles arise for these residents to exercise their autonomy in daily life, and identifying and analysing how autonomy is expressed in the meeting between residents and staff. The study applies an ethnographic approach, using methods including field studies with observations and videotaped meetings between residents and staff. The sample consists of residents aged 65 and over and staff at three group homes for people with intellectual disability. One resident at each group home is followed in greater depth. The analysis uses the time-geographic concepts of project, activity and restrictions in order to clarify where and when different projects are carried out, as well as who has the power to determine what is to be carried out. Interaction analysis is used to analyse the videotaped meetings between residents and staff. The analysis is based on Goffman’s interaction order and interaction rituals, theories about turntaking, both verbal and non-verbal, and theories about power and counter-power. In accordance with Goffman’s framework concept, the starting point is the concrete framework that reflects spatiality, which in turn becomes a way to place the more abstract framework of the situation into a specific context. Two major projects were identified: Sleep and Rest and Meals. The analysis reveals projects that are governed by the resident’s own preferences (individual projects) and projects that are governed to a greater degree by the staff’s objectives and opportunities (institutional projects). Some guidance also derives from municipal decisions and guidelines (organizational projects). Many projects were carried out based on staff decisions and objectives, but in actual practice many projects failed to get off the ground. Some projects were at risk of failure until something happened or someone intervened and thereby rescued the project so that it could be implemented. The interactional analysis perspective shows how autonomy is constructed in the meeting. Autonomy is situation-bound, and shifts more on the basis of context than in relation to specific individuals. The study includes decision situations mainly between autonomy and its opposite, paternalism, which are viewed as extremes on a continuum. However, certain factors lead to stronger autonomy in certain situations. When a resident can define the situation, they also have greater power to determine the outcome. In situations characterized by paternalism, the staff have a preferential right of interpretation and the power to decide, both on the basis of their knowledge and because of the asymmetrical interdependence that characterizes the resident-professional relationship. Such situations are also governed by the rules and procedures of the group home to a greater degree than those situations in which the resident exercises autonomy. The thesis discusses strategies that could increase the residents’ opportunities for autonomy. Greater communication skills among staff can be viewed as a step on the path toward greater autonomy for the residents. Staff have the potential to eliminate obstacles, to strengthen inadequate skills or create new ones by providing choices and assistive devices, and to exercise an affirmative approach.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper explores the role of information and communication technologies in managing risk and early discharge patients, and suggests innovative actions in the area of E-Health services. Treatments of chronic illnesses, or treatments of special needs such as cardiovascular diseases, are conducted in long-stay hospitals, and in some cases, in the homes of patients with a follow-up from primary care centre. The evolution of this model is following a clear trend: trying to reduce the time and the number of visits by patients to health centres and derive tasks, so far as possible, toward outpatient care. Also the number of Early Discharge Patients (EDP) is growing, thus permiting a saving in the resources of the care center. The adequacy of agent and mobile technologies is assessed in light of the particular requirements of health care applications. A software system architecture is outlined and discussed. The major contributions are: first, the conceptualization of multiple mobile and desktop devices as part of a single distributed computing system where software agents are being executed and interact from their remote locations. Second, the use of distributed decision making in multiagent systems, as a means to integrate remote evidence and knowledge obtained from data that is being collected and/or processed by distributed devices. The system will be applied to patients with cardiovascular or Chronic Obstructive Pulmonary Diseases (COPD) as well as to ambulatory surgery patients. The proposed system will allow to transmit the patient's location and some information about his/her illness to the hospital or care centre

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Solving a complex Constraint Satisfaction Problem (CSP) is a computationally hard task which may require a considerable amount of time. Parallelism has been applied successfully to the job and there are already many applications capable of harnessing the parallel power of modern CPUs to speed up the solving process. Current Graphics Processing Units (GPUs), containing from a few hundred to a few thousand cores, possess a level of parallelism that surpasses that of CPUs and there are much less applications capable of solving CSPs on GPUs, leaving space for further improvement. This paper describes work in progress in the solving of CSPs on GPUs, CPUs and other devices, such as Intel Many Integrated Cores (MICs), in parallel. It presents the gains obtained when applying more devices to solve some problems and the main challenges that must be faced when using devices with as different architectures as CPUs and GPUs, with a greater focus on how to effectively achieve good load balancing between such heterogeneous devices.

Relevância:

50.00% 50.00%

Publicador:

Resumo:

This study examined the acoustical conditions, including the surface-dimension measurements, background noise levels, and reverberation times in classrooms in a metropolitan area. The data collected in this study will help school administrators realize that appropriate classroom acoustics are necessary for both hearing impaired and normal hearing students.

Relevância:

50.00% 50.00%

Publicador:

Resumo:

The goal of this research is to provide a framework for vibro-acoustical analysis and design of a multiple-layer constrained damping structure. The existing research on damping and viscoelastic damping mechanism is limited to the following four mainstream approaches: modeling techniques of damping treatments/materials; control through the electrical-mechanical effect using the piezoelectric layer; optimization by adjusting the parameters of the structure to meet the design requirements; and identification of the damping material’s properties through the response of the structure. This research proposes a systematic design methodology for the multiple-layer constrained damping beam giving consideration to vibro-acoustics. A modeling technique to study the vibro-acoustics of multiple-layered viscoelastic laminated beams using the Biot damping model is presented using a hybrid numerical model. The boundary element method (BEM) is used to model the acoustical cavity whereas the Finite Element Method (FEM) is the basis for vibration analysis of the multiple-layered beam structure. Through the proposed procedure, the analysis can easily be extended to other complex geometry with arbitrary boundary conditions. The nonlinear behavior of viscoelastic damping materials is represented by the Biot damping model taking into account the effects of frequency, temperature and different damping materials for individual layers. A curve-fitting procedure used to obtain the Biot constants for different damping materials for each temperature is explained. The results from structural vibration analysis for selected beams agree with published closed-form results and results for the radiated noise for a sample beam structure obtained using a commercial BEM software is compared with the acoustical results of the same beam with using the Biot damping model. The extension of the Biot damping model is demonstrated to study MDOF (Multiple Degrees of Freedom) dynamics equations of a discrete system in order to introduce different types of viscoelastic damping materials. The mechanical properties of viscoelastic damping materials such as shear modulus and loss factor change with respect to different ambient temperatures and frequencies. The application of multiple-layer treatment increases the damping characteristic of the structure significantly and thus helps to attenuate the vibration and noise for a broad range of frequency and temperature. The main contributions of this dissertation include the following three major tasks: 1) Study of the viscoelastic damping mechanism and the dynamics equation of a multilayer damped system incorporating the Biot damping model. 2) Building the Finite Element Method (FEM) model of the multiple-layer constrained viscoelastic damping beam and conducting the vibration analysis. 3) Extending the vibration problem to the Boundary Element Method (BEM) based acoustical problem and comparing the results with commercial simulation software.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The release of ultrafine particles (UFP) from laser printers and office equipment was analyzed using a particle counter (FMPS; Fast Mobility Particle Sizer) with a high time resolution, as well as the appropriate mathematical models. Measurements were carried out in a 1 m³ chamber, a 24 m³ chamber and an office. The time-dependent emission rates were calculated for these environments using a deconvolution model, after which the total amount of emitted particles was calculated. The total amounts of released particles were found to be independent of the environmental parameters and therefore, in principle, they were appropriate for the comparison of different printers. On the basis of the time-dependent emission rates, “initial burst” emitters and constant emitters could also be distinguished. In the case of an “initial burst” emitter, the comparison to other devices is generally affected by strong variations between individual measurements. When conducting exposure assessments for UFP in an office, the spatial distribution of the particles also had to be considered. In this work, the spatial distribution was predicted on a case by case basis, using CFD simulation.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Field and laboratory measurements identified a complex relationship between odour emission rates provided by the US EPA dynamic emission chamber and the University of New South Wales wind tunnel. Using a range of model compounds in an aqueous odour source, we demonstrate that emission rates derived from the wind tunnel and flux chamber are a function of the solubility of the materials being emitted, the concentrations of the materials within the liquid; and the aerodynamic conditions within the device – either velocity in the wind tunnel, or flushing rate for the flux chamber. The ratio of wind tunnel to flux chamber odour emission rates (OU m-2 s) ranged from about 60:1 to 112:1. The emission rates of the model odorants varied from about 40:1 to over 600:1. These results may provide, for the first time, a basis for the development of a model allowing an odour emission rate derived from either device to be used for odour dispersion modelling.