DC/DC converter 3D assembly for autonomous sensor nodes

This paper reports on the design and the manufacturing of an integrated DCDC converter, which respects the specificity of sensor node network: compactness, high efficiency in acquisition and transmission modes, and compatibility with miniature Lithium batteries. A novel integrated circuit (ASIC) has been designed and manufactured to provide regulated Voltage to the sensor node from miniaturized, thin film Lithium batteries. Then, a 3D integration technique has been used to integrate this ASIC in a 3 layers stack with high efficiency passives components, mixing the wafer level technologies from two different research institutions. Electrical results have demonstrated the feasibility of this integrated system and experiments have shown significant improvements in the case of oscillations in regulated voltage. However, stability of this output voltage toward the input voltage has still to be improved.

Statistical method of modeling and optimization for wireless sensor nodes with different interconnect technologies and substrates

A comparison study was carried out between a wireless sensor node with a bare die flip-chip mounted and its reference board with a BGA packaged transceiver chip. The main focus is the return loss (S parameter S11) at the antenna connector, which was highly depended on the impedance mismatch. Modeling including the different interconnect technologies, substrate properties and passive components, was performed to simulate the system in Ansoft Designer software. Statistical methods, such as the use of standard derivation and regression, were applied to the RF performance analysis, to see the impacts of the different parameters on the return loss. Extreme value search, following on the previous analysis, can provide the parameters' values for the minimum return loss. Measurements fit the analysis and simulation well and showed a great improvement of the return loss from -5dB to -25dB for the target wireless sensor node.

Design and implementation of the embedded capacitance layers for decoupling of wireless sensor nodes

In this paper, the embedded capacitance material (ECM) is fabricated between the power and ground layers of the wireless sensor nodes, forming an integrated capacitance to replace the large amount of decoupling capacitors on the board. The ECM material, whose dielectric constant is 16, has the same size of the wireless sensor nodes of 3cm*3cm, with a thickness of only 14μm. Though the capacitance of a single ECM layer being only around 8nF, there are two reasons the ECM layers can still replace the high frequency decoupling capacitors (100nF in our case) on the board. The first reason is: the parasitic inductance of the ECM layer is much lower than the surface mount capacitors'. A smaller capacitance value of the ECM layer could achieve the same resonant frequency of the surface mount decoupling capacitors. Simulation and measurement fit this assumption well. The second reason is: more than one layer of ECM material are utilized during the design step to get a parallel connection of the several ECM capacitance layers, finally leading to a larger value of the capacitance and smaller value of parasitic. Characterization of the ECM is carried out by the LCR meter. To evaluate the behaviors of the ECM layer, time and frequency domain measurements are performed on the power-bus decoupling of the wireless sensor nodes. Comparison with the measurements of bare PCB board and decoupling capacitors solution are provided to show the improvement of the ECM layer. Measurements show that the implementation of the ECM layer can not only save the space of the surface mount decoupling capacitors, but also provide better power-bus decoupling to the nodes.

Dutch influence in the urban landscape of Cork City pre-1800: Fact or myth?

The early years of the eighteenth century Irish port town, Cork saw an expansion of its city limits, an era of reconstruction both within and beyond the walls of its Medieval townscape and a reclamation of its marshlands to the east and west. New people, new ideas and the beginnings of new wealth infused the post Elizabethan character of the recently siege battered city. It also brought a desire for something different, something new, an opportunity to redefine the ambience and visual perception of the urban landscape and thereby make a statement about its intended cultural and social orientations. It brought an opportunity to re-imagine and model a new, continental style of place and surrounding environment.

Development of miniaturized wireless sensor nodes suitable for building energy management and modelling

Buildings consume 40% of Ireland's total annual energy translating to 3.5 billion (2004). The EPBD directive (effective January 2003) places an onus on all member states to rate the energy performance of all buildings in excess of 50m2. Energy and environmental performance management systems for residential buildings do not exist and consist of an ad-hoc integration of wired building management systems and Monitoring & Targeting systems for non-residential buildings. These systems are unsophisticated and do not easily lend themselves to cost effective retrofit or integration with other enterprise management systems. It is commonly agreed that a 15-40% reduction of building energy consumption is achievable by efficiently operating buildings when compared with typical practice. Existing research has identified that the level of information available to Building Managers with existing Building Management Systems and Environmental Monitoring Systems (BMS/EMS) is insufficient to perform the required performance based building assessment. The cost of installing additional sensors and meters is extremely high, primarily due to the estimated cost of wiring and the needed labour. From this perspective wireless sensor technology provides the capability to provide reliable sensor data at the required temporal and spatial granularity associated with building energy management. In this paper, a wireless sensor network mote hardware design and implementation is presented for a building energy management application. Appropriate sensors were selected and interfaced with the developed system based on user requirements to meet both the building monitoring and metering requirements. Beside the sensing capability, actuation and interfacing to external meters/sensors are provided to perform different management control and data recording tasks associated with minimisation of energy consumption in the built environment and the development of appropriate Building information models(BIM)to enable the design and development of energy efficient spaces.

Understanding teacher collaboration in disadvantaged urban primary schools: uncovering practices that foster professional learning communities

This study is set in the context of disadvantaged urban primary schools in Ireland. It inquires into the collaborative practices of primary teachers exploring how class teachers and support teachers develop ways of working together in an effort to improve the literacy and numeracy levels of their student. Traditionally teachers have worked in isolation and therefore ‘collaboration’ as a practice has been slow to permeate the historically embedded assumption of how a teacher should work. This study aims to answer the following questions. 1). What are the dynamics of teacher collaboration in disadvantaged urban primary schools? 2). In what ways are teacher collaboration and teacher learning related? 3). In what ways does teacher collaboration influence students’ opportunities for learning? In answering these research questions, this study aims to contribute to the body of knowledge pertaining to teacher learning through collaboration. Though current policy and literature advocate and make a case for the development of collaborative teaching practices, key studies have identified gaps in the research literature in relation to the impact of teacher collaboration in schools. This study seeks to address some of those gaps by establishing how schools develop a collaborative environment and how teaching practices are enacted in such a setting. It seeks to determine what skills, relationships, structures and conditions are most important in developing collaborative environments that foster the development of professional learning communities (PLCs). This study uses a mixed method research design involving a postal survey, four snap-shot case studies and one in depth case study in an effort to establish if collaborative practice is a feasible practice resulting in worthwhile benefits for both teachers and students.

Place, teenagers and urban identities: Growing up in the revanchist city

The recreational lives of teenagers in Ireland has been the subject of much debate in recent years. The subject has received much attention from academics, particularly in the UK and the US. In Ireland there is a dearth of research on, and a poor understanding of teenagers recreational lives. Additionally much of the research from the UK and the US to date has been focused on teenagers’ use of the street for recreation, arguing that teenagers are increasingly pushed out of public space. The research frequently emphasises teenagers’ resistance against adult hegemony. This thesis explores the recreational geographies of teenagers living in two socially and economically distinct neighbourhoods in Cork. It seeks to fill in gaps in knowledge of teenagers recreational lives in Ireland and contribute to geographical wisdom on teenagers’ geographies. Using a mixed method approach and a variety of thinking tools this research shows that teenagers living in Cork are growing up in a revanchist society. The thesis demonstrates how teenagers’ recreational practices are currently being configured in Irish society, unfolding strategies of dominance and affection which construct and regulate the recreational lives of teenagers. The effects of revanchism on teenagers’ experiences of outdoor space for recreation are also pursued. Furthermore the socio-spatial contingencies of teenagers’ recreational lives and revanchism are probed throughout the thesis, but in greater depth in the final chapters. The work also addresses an under-researched aspect of young people’s recreational - relationships with pets. Lastly, the subject of teenagers’ right to urban space is critically analysed.

Urbanization effects on welfare and income diversification strategies of peri-urban farm households in Tigray, Northern Ethiopia: An empirical analysis

Urban areas in many developing countries are expanding rapidly by incorporating nearby subsistence farming communities. This has a direct effect on the consumption and production behaviours of the farm households but empirical evidence is sparse. This thesis investigated the effects of rapid urbanization and the associated policies on welfare of subsistence farm households in peri-urban areas using a panel dataset from Tigray, Ethiopia. The study revealed a number of important issues emerging with the rapid urban expansion. Firstly, private asset holdings and consumption expenditure of farm households, that have been incorporated into urban administration, has decreased. Secondly, factors that influence the farm households’ welfare and vulnerability depend on the administration they belong to, urban or rural. Gender and literacy of the household head have significant roles for the urban farm households to fall back into and/or move out of poverty. However, livestock holding and share of farm income are the most important factors for rural households. Thirdly, the study discloses that farming continues to be important source of income and income diversification is the principal strategy. Participation in nonfarm employment is less for farm households in urban than rural areas. Adult labour, size of the local market and past experience in the nonfarm sector improves the likelihood of engaging in skilled nonfarm employment opportunities. But money, given as compensation for the land taken away, is not crucial for the household to engage in better paying nonfarm employments. Production behaviour of the better-off farm households is the same, regardless of the administration they belong to. However, the urban poor participate less in nonfarm employment compared to the rural poor. These findings signify the gradual development of urban-induced poverty in peri-urban areas. In the case of labour poor households, introducing urban safety net programmes could improve asset productivity and provide further protection.

Real time analysis of atmospheric single particles in urban environments using aerosol time of flight mass spectrometry

In order to determine the size-resolved chemical composition of single particles in real-time an ATOFMS was deployed at urban background sites in Paris and Barcelona during the MEGAPOLI and SAPUSS monitoring campaigns respectively. The particle types detected during MEGAPOLI included several carbonaceous species, metal-containing types and sea-salt. Elemental carbon particle types were highly abundant, with 86% due to fossil fuel combustion and 14% attributed to biomass burning. Furthermore, 79% of the EC was apportioned to local emissions and 21% to continental transport. The carbonaceous particle types were compared with quantitative measurements from other instruments, and while direct correlations using particle counts were poor, scaling of the ATOFMS counts greatly improved the relationship. During SAPUSS carbonaceous species, sea-salt, dust, vegetative debris and various metal-containing particle types were identified. Throughout the campaign the site was influenced by air masses altering the composition of particles detected. During North African air masses the city was heavily influenced by Saharan dust. A regional stagnation was also observed leading to a large increase in carbonaceous particle counts. While the ATOFMS provides a list of particle types present during the measurement campaigns, the data presented is not directly quantitative. The quantitative response of the ATOFMS to metals was examined by comparing the ion signals within particle mass spectra and to hourly mass concentrations of; Na, K, Ca, Ti, V, Cr, Mn, Fe, Zn and Pb. The ATOFMS was found to have varying correlations with these metals depending on sampling issues such as matrix effects. The strongest correlations were observed for Al, Fe, Zn, Mn and Pb. Overall the results of this work highlight the excellent ability of the ATOFMS in providing composition and mixing state information on atmospheric particles at high time resolution. However they also show its limitations in delivering quantitative information directly.