Human body motion capture systems based on inertial sensors (gyroscopes andaccelerometers) are able to track the relative motions in the body precisely, oftenwith the aid of supplementary sensors. The sensor measurements are combinedthrough a sensor fusion algorithm to create estimates of, among other parame-ters, position, velocity and orientation for each body segment. As this algorithmrequires integration of noisy measurements, some drift, especially in the positionestimate, is expected. Taking advantage of the knowledge about the tracked sub-ject, a human body, models have been developed that improve the estimates, butposition still displays drift over time.In this thesis, a GNSS receiver is added to the motion capture system to givea drift-free measurement of the position as well as a velocity measurement. Theinertial data and the GNSS data complements each other well, particularly interms of observability of global and relative motions. To enable the models of thehuman body at an early stage of the fusion of sensor data, an optimization basedmaximum a posteriori algorithm was used, which is also better suited for thenonlinear system tracked compared to the conventional method of using Kalmanfilters.One of the models that improves the position estimate greatly, without addingadditional sensing, is the contact detection, with which the velocity of a segmentis set to zero whenever it is considered stationary in comparison to the surround-ing environment, e.g. when a foot touches the ground. This thesis looks at botha scenario when this contact detection can be applied and a scenario where itcannot be applied, to see what possibilities an addition of GNSS sensor couldbring to the human body motion tracking case. The results display a notable im-provement in position, both with and without contact detection. Furthermore,the heading estimate is improved at a full-body scale and the solution makes theestimates depend less on acceleration bias estimation.These results show great potential for more accurate estimates outdoors andcould prove valuable for enabling motion tracking of scenarios where the contactdetection model cannot be used, such as e.g. biking.

A variabilidade espacial do desenvolvimento das plantas cultivadas em áreas extensas pode ser caracterizada com diversas estratégias, havendo sensores específicos e aqueles que indiretamente permitem inferir sobre o porte e biomassa. O uso de sensores de reflectância embarcados em plataformas orbitais, aéreas ou terrestres são fontes importantes de informação, mas não permitem obter informações de forma direta sobre a altura das plantas além de apresentarem alta sensibilidade às condições de iluminação no momento da coleta. Sensores ultrassônicos para mensurar a distância até o topo das plantas cultivadas são empregados comumente em operações nas quais se deseja manter uma distância entre órgãos das máquinas e as plantas, porém não permitem obter informações precisas sobre o porte das plantas, uma vez que usualmente são fixados em partes móveis, além de serem também sensíveis a variáveis do ambiente como poeira e ventos. Os radares são sensores ativos amplamente utilizados em aplicações em que se deseja mensurar distâncias. Há sistemas orbitais capazes de empregar radiação que penetra em dosséis de vegetações permitindo o cálculo de sua altura. O uso de radares em curtas distâncias requer dispositivos com capacidade de mensurar o tempo em alta resolução o que os torna caros. Através da modulação de sinais é possível o emprego de dispositivos mais simples mantendo a efetividade na determinação da distância. O objetivo deste trabalho foi investigar o uso de um tipo de sistema radar, de baixo custo, que pode ser acoplado a veículos terrestres para a mensuração de distâncias curtas. Foi desenvolvido um sistema de mensuração de distância baseado em micro-ondas moduladas. A modulação em duas frequências distintas permitiu obter medidas até alvos com características distintas e.g. alvos representativos do topo do dossel e da superfície do terreno. Houve uma relação exponencial entre a distância aos alvos e a frequência de batidas do sinal modulado. O sistema foi acoplado em um trator e caracterizou-se seu desempenho em alvos com dimensões conhecidas, demonstrando haver efeito do formato e tamanho do alvo sobre a qualidade da medida de distância. Também foi realizada a comparação com um sensor de reflectância do infravermelho em uma lavoura de milheto (Pennisetum glaucum). Os resultados demonstraram o potencial da técnica, com boas relações entre as leituras de frequência de batidas e distância do alvo quando este apresenta dimensões superiores ao campo de visada do sensor. As leituras de distância até o terreno na presença de um obstáculo foram, entretanto influenciadas pela distância do obstáculo ao sensor. Uma comparação com leituras de um sensor de reflectância foi realizada em uma lavoura que apresentava variabilidade espacial identificando uma relação inversa entre as leituras do sensor com as de reflectância. / Spatial variability of growth for row crops cultivated in extensive areas can be characterized using several strategies from specific sensors and those that allow indirectly infer about height and biomass. The use of reflectance sensors embedded in orbital, aerial or terrestrial platforms are important sources of information but do not allow direct information on plant height, besides being highly sensitive to lighting conditions at the time of collection. Ultrasonic sensors can be employed for the measurement of distances and are already used in many agricultural operations in which there is a requirement to maintain a distance between machine components and plants. Such sensors, however, doesn\'t allow to obtain information about the size of the plants, since they are usually fixed in moving parts, as well as being sensitive to environmental variables such as dust and wind. Radars are active sensors widely used in applications where distances should be measured. Many orbital radar systems are capable of employing radiation that penetrates vegetation canopies allowing the calculation of its height. The use of radars at short distances requires devices with the ability to measure time at a high resolution which make them expensive. Through the modulation of signals, it is possible to use simpler devices while maintaining the effectiveness in determining the distance. The objective of this research was to investigate the use of a low-cost radar system, which can be attached to terrestrial vehicles for the measurement of short distances. A distance measurement system based on modulated microwave radiantion was developed. Signal modulation in two frequencies allowed obtaining measurements from targets with distinct characteristics e.g. targets representative of the top of the canopy and terrain surface. There was an exponential relationship between distance to the targets and the beating frequency of modulated signals. The system was installed on a tractor and its performance was characterized in targets with known dimensions, demonstrating the effect of the size and shape of the target on the quality of the distance measurement. Comparison was also made with a reference infrared reflected sensor in a millet (Pennisetum glaucum) crop. The results demonstrated the potential of the technique, with good relations between the signal beating frequency and target distance readings when the target is larger than the sensor\'s footprint. Distance to the ground measurements when in the presence of an obstacle were influenced by the distance from the obstacle to the sensor. A comparison with readings of a reflectance sensor was performed in a crop that had spatial variability, an inverse relationship between sensor and reflectance readings was found.

Currently, the most common strategy employed to detect DNA sequences is PCR (Polymerase Chain Reaction). Nevertheless, in the last few years research on DNA biosensors has increased significantly. Such sensors represent an alternative to PCR in the detection of specific DNA sequences, once they exhibit fast response, low limits of detection, and require simpler sample preparation. The development of a biosensor for detection of DNA from Human Papillomavirus type 18 is reported. To immobilise DNA probe onto indium-tin oxide (ITO) electrodes, a silanisation was carried out using 3-Aminopropyltryethoxysilane (APTES). Silanisation was studied and optimised using ultra-violet absorption spectroscopy, atomic force microscopy, fluorescence microscopy, and cyclic voltammetry. After immobilisation, the hybridisation with target sequence is detected by changes in surface properties of ITO electrode by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy, using the Ferri-Ferrocyante redox couple. The detection of synthetic target sequence was performed in the range of 12.5 to 100 nM, and 300nM for PCR products. The sensor did not show significative response for non-complementary sequence at 50 nM. This sensor can be applied for fast and low cost detection of HPV genetic material at nanomolar levels. / A estratégia mais empregada atualmente na detecção de sequência de DNA é a PCR (Reação em Cadeira da Polimerase). Contudo, nos últimos anos, a pesquisa em biossensores de DNA tem aumentado significativamente. Estes sensores representam uma alternativa a PCR na detecção de sequências específicas de DNA, uma vez que exibem resposta rápida, baixos limites de detecção e requerem preparação simples da amostra. Nesta dissertação descrito o desenvolvimento de um biossensor para a detecção do DNA do Papilomavirus Humano tipo 18. A fim de imobilizar a sequência de captura de DNA em eletrodos de óxido de estanho e índio (ITO), realizou-se uma silanização usando 3-Aminopropiltrietoxisilano (APTES). A reação de silanização foi estudada e otimizada através das técnicas de Espectroscopia de Absorção Ultravioleta, Microscopia de Força Atômica, Microscopia de Fluorescência e Voltametria Cíclica. Após a imobilização, a hibridização com a sequência alvo é detectada através de alterações nas propriedades de superfície do eletrodo através de Voltametria Cíclica e Espectroscopia de Impedância Eletroquímica, usando o par redox Ferri-ferrocianeto. A detecção da sequência alvo sintética foi realizada no intervalo de 12.5 a 100 nM, e para o produto de PCR, 300 nM. O sensor não demonstrou resposta significativa para sequência não complementar a 50 nM. Este sensor pode ser aplicado na detecção rápida e de baixo custo de material genético do HPV a níveis nanomolares.

Philosophiae Doctor - PhD / Wireless sensor networks (WSNs) have become a popular research area that is widely gaining the attraction from both the research and the practitioner communities due to their wide area of applications. These applications include real-time sensing for audio delivery, imaging, video streaming, and remote monitoring with positive impact in many fields such as precision agriculture, ubiquitous healthcare, environment protection, smart cities and many other fields. While WSNs are aimed to constantly handle more intricate functions such as intelligent computation, automatic transmissions, and in-network processing, such capabilities are constrained by their limited processing capability and memory footprint as well as the need for the sensor batteries to be cautiously consumed in order to extend their lifetime. This thesis revisits the issue of the energy efficiency in sensor networks by proposing a novel clustering approach for routing the sensor readings in wireless sensor networks. The main contribution of this dissertation is to 1) propose corrective measures to the traditional energy model adopted in current sensor networks simulations that erroneously discount both the role played by each node, the sensor node capability and fabric and 2) apply these measures to a novel hierarchical routing architecture aiming at maximizing sensor networks lifetime. We propose three energy models for sensor network: a) a service-aware model that account for the specific role played by each node in a sensor network b) a sensor-aware model and c) load-balancing energy model that accounts for the sensor node fabric and its energy footprint. These two models are complemented by a load balancing model structured to balance energy consumption on the network of cluster heads that forms the backbone for any cluster-based hierarchical sensor network. We present two novel approaches for clustering the nodes of a hierarchical sensor network: a) a distanceaware clustering where nodes are clustered based on their distance and the residual energy and b) a service-aware clustering where the nodes of a sensor network are clustered according to their service offered to the network and their residual energy. These approaches are implemented into a family of routing protocols referred to as EOCIT (Energy Optimization using Clustering Techniques) which combines sensor node energy location and service awareness to achieve good network performance. Finally, building upon the Ant Colony Optimization System (ACS), Multipath Routing protocol based on Ant Colony Optimization approach for Wireless Sensor Networks (MRACO) is proposed as a novel multipath routing protocol that finds energy efficient routing paths for sensor readings dissemination from the cluster heads to the sink/base station of a hierarchical sensor network. Our simulation results reveal the relative efficiency of the newly proposed approaches compared to selected related routing protocols in terms of sensor network lifetime maximization.

<p>Communication in a sensor network needs guaranteed reception of data without fail and providing security to it. The authenticity and confidentiality of the data has to be ensured as sensors have limited hardware resources as well as the bandwidth. This thesis addresses the security aspects in wireless sensor networks. The main task of the project is to identify the critical security parameters for these distributed embedded systems. The sensors have extremely limited resources: small amount of memory, low computation capability and poor bandwidth. For example, a sensor platform can have 8KB of flash memory, a 4MHz 8-bit Atmel processor, and a 900MHz radio interface. Various security threats posed to these small wireless sensor networks has been made and solutions proposed. Secure communication between these communicating partners is to be achieved using cryptography.</p>

<p>In the recent past, wireless sensor networks have been introduced to use in many applications. To </p><p>design the networks, the factors needed to be considered are the coverage area, mobility, power </p><p>consumption, communication capabilities etc. The challenging goal of our project is to create a </p><p>simulator to support the wireless sensor network simulation. The network simulator (NS-2) which </p><p>supports both wire and wireless networks is implemented to be used with the wireless sensor </p><p>network. This implementation adds the sensor network classes which are environment, sensor </p><p>agent and sensor application classes and modifies the existing classes of wireless network in NS- </p><p>2. This NS-2 based simulator is used to test routing protocols – Destination-Sequenced Distance </p><p>Vector (DSDV), and Ad-Hoc On-Demand Distance Vector (AODV) as one part of simulations. </p><p>Finally, the sensor network application models and the extension methods of this NS-2 based </p><p>simulator for simulations in specific wireless sensor network applications are proposed.</p>

The performance of smart structures depends on the electromechanical behaviour of piezoelectric sensors/actuators and the bonding condition along the interface, which connects the sensor/actuator and the host structures. This thesis documents a theoretical study of the influence of material parameters of the imperfect bonding layer on the coupled electromechanical characteristics of piezoelectric sensors/actuators. A one dimensional sensor/actuator model with an imperfect bonding layer, which undergoes a shear deformation, is proposed. The emphasis of the current study is on the local stress and strain fields near imperfectly bonded sensors/actuators and the load transfer. Analytical solutions based on the integral equation method are provided. Detailed numerical simulation is conducted to evaluate the influence of the geometry and the material mismatch of the adhesive layer upon the sensing/actuating process. The interfacial debonding and its effect upon the strain/stress distribution and the overall performance of the integrated structure are evaluated in detail.

CytoSensor system integration and design is driven by requirements generated by the need to complete biological experiment operations. The system is used for toxin-based detection which will identify and quantify unknown input toxins by using a biosensor based on a living fish chromatophore. The system consists of 3 main parts: biosensor, data acquisition and data interpretation. This thesis is focused on data acquisition. Acquisition, in this case, is via a color camera since the cells have an easily measurable visual output. The major initial task is to select the hardware specifications that satisfy user requirements. Components are obtained from different vendors. The understanding of each component is, therefore, very important to maximize the system performance and compatibility. The second major task is to design the software interface and components to manage the data acquisition. This can be separated into 2 parts. The first part is acquisition management and control. The second part is the human interface. This thesis focuses on the human interface. The human interface is the part that communicates between the user and the system. The system will send the system status to the user. The user will then direct the system through the operation. Operators may not be familiar with complicated computerized systems. A user-friendly interface is important to reduce mistakes and to facilitate the operation. The goal of this design is to direct the user from a single look at the interface. The interface should therefore contain all the useful and necessary information. The design of the user interface begins with gathering the necessary information and making a decision about which information is important to deliver to the user. A clean, tidy and informative user interface will lead to efficient operation. The design methodology is to group the same information within the same area and be consistent. Machine operation is very important, as well. In order to reduce the confusion in system operation, the machine operating protocol is designed to be very similar to the traditional protocol. Design of the machine operation is through interactions with the user. Sending user information to the machine will be handled by the system management program. By simulating the user scenario, each state change will lead to changing of the state of the machine, as well. The scenario is implemented in a state-like diagram. This state diagram must be implemented carefully in order to be able to handle all the cases and exceptions. The last and most important part is putting all the components together and testing the system. All possible scenarios and features listed before designing will be tested at this point. The last test is to run actual experiments with the system. After all the tests are satisfied, the system is delivered to the user. At this time, the user might give more feedback on the system. In conclusion, the overall goal of designing this system is not only to make the system for this specific application. However, the goal is to design a general application that will be able to apply to different sensor application. By changing the core management and hardware, the software can easily fit another sensor application. / Graduation date: 2003

This paper discusses how sparse local measurements of positions and surface normals may be used to identify and locate overlapping objects. The objects are modeled as polyhedra (or polygons) having up to six degreed of positional freedom relative to the sensors. The approach operated by examining all hypotheses about pairings between sensed data and object surfaces and efficiently discarding inconsistent ones by using local constraints on: distances between faces, angles between face normals, and angles (relative to the surface normals) of vectors between sensed points. The method described here is an extension of a method for recognition and localization of non-overlapping parts previously described in [Grimson and Lozano-Perez 84] and [Gaston and Lozano-Perez 84].

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 139-148). Also available in electronic version.