Single link flexible beam testbed project

This thesis describes the single link flexible beam testbed at the CLaMS laboratory in terms of its hardware, software, and linear model, and presents two controllers, each including a hub angle proportional-derivative (PD) feedback compensator and one augmented by a second static gain full state feedback loop, based upon a synthesized strictly positive real (SPR) output, that increases specific flexible mode pole damping ratios w.r.t the PD only case and hence reduces unwanted residual oscillation effects. Restricting full state feedback gains so as to produce a SPR open loop transfer function ensures that the associated compensator has an infinite gain margin and a phase margin of at least (-90, 90) degrees. Both experimental and simulation data are evaluated in order to compare some different observer performance when applied to the real testbed and to the linear model when uncompensated flexible modes are included

Dental and nondental stem cell based regeneration of the craniofacial region: a tissue based approach

Craniofacial reconstruction may be a necessary treatment for those who have been affected by trauma, disease, or pathological developmental conditions. The use of stem cell therapy and tissue engineering shows massive potential as a future treatment modality. Currently in the literature, there is a wide variety of published experimental studies utilising the different stem cell types available and the plethora of available scaffold materials. This review investigates different stem cell sources and their unique characteristics to suggest an ideal cell source for regeneration of individual craniofacial tissues. At present, understanding and clinical applications of stem cell therapy remain in their infancy with numerous challenges to overcome. In spite of this, the field displays immense capacity and will no doubt be utilised in future clinical treatments of craniofacial regeneration

Managing an Unstable Housing Market

AbstractIn this paper it is intended to place the recent experience of the Irish housing market in the context of economic and property market cycles, how these interact over a property cycle and lessons from recent policy experience including interventions in the housing area. In spatial terms the currenthousing market can be seen as the result of an ad-hoc development led urban growth pattern which contributed to a dispersed development pattern with problems in oversupply. It is clear that alternative options exist to this approach and that evidence based management systems in terms of planning, development and financial decisions will be required to reduce the severity of future property market corrections. The incidence of rapidly increasing residential property prices has been a feature of many international economies in the past decade. This has resulted in house price surges and corrections across much of the industrialised world. Factors associated with such surges include growth in housing demand often supported by relaxed monetary policy stances, planning and zoning systems and fiscal regimes which encourage the investment in residential property acquisition anddevelopment. The falling prices for housing in Ireland in 2007-2010 nationally has created a stagnating effect with purchasers reluctant to enter the market while the price correction is worked through. In turn suppliers, construction interests and vendors are highly reluctant to accept lower bid prices in the market due to often unrealistic expectations created during the long boom. The result of oversupply is falling prices, reduced occupation demand and decreased investor demand, leading to lower building activity and profitability. In addition the banking and liquidity crisis have contributed to a radical deterioration in economic circumstances and increasing out-migration. As part of the Urban Environment Project at UCD this working paper considers the current evidence of a market correction and oversupply in the Dublin region and Ireland based on data available up to March 2010 including the authors’ working projections for 2010

Highly efficient p-i-n perovskite solar cells that endure temperature variations

Daily temperature variations induce phase transitions and lattice strains in halide perovskites, challenging their stability in solar cells. We stabilised the perovskite black phase and improved the solar cell performance using the ordered dipolar structure of β-poly(1,1-difluoroethylene) to control the perovskite film crystallisation and the energy alignment. We demonstrated p-i-n perovskite solar cells with a record power conversion efficiency of 24.6% over 18 square millimetres and 23.1% over 1 square centimetre, which retained 96% and 88% of the efficiency after 1000-hours 1-sun maximum power point tracking at 25 and 75 °C, respectively. Devices under rapid thermal cycling between −60 °C and +80 °C showed no sign of fatigue, demonstrating the impact of the ordered dipolar structure on the operational stability of perovskite solar cells

Age-induced excellence with green solvents: the impact of residual solvent and post-treatments in screen-printed carbon perovskite solar cells and modules

Printable mesoscopic carbon perovskite solar cells (CPSCs) are cited as a potential frontrunner to commercialisation, as they are fabricated using low-cost screen printing. CPSCs produced using different perovskite precursor solvents benefit from different post-treatments. For example, cells made with DMF/DMSO precursors improve with light exposure, whereas γ-butyrolactone cells require humidity exposure for peak performance. Understanding the evolution of devices fabricated using different systems is therefore key to maximising PCE. This work examines the performance evolution of CPSCs and modules fabricated with low toxicity γ-valerolactone based precursors. It is found that PCE improves independently of humidity or light exposure due to gradual residual solvent loss and associated crystal realignment in the days following fabrication. In 1 cm2 cells significant Voc and FF produced an average increase of ∼15% on initial PCE, with some devices nearly doubling in performance. Similarly, 220 cm2 modules were also found to experience PCE increases. Critically, it appears this ageing step is essential for peak performance, as early encapsulation and extended heating impaired both performance and stability. This work may therefore help inform future work designing scaled-up processes for fabricating and encapsulating high performing CPSC modules

Effectiveness of poly(methyl methacrylate) spray encapsulation for perovskite solar cells

For commercial applications, Perovskite Solar Cells (PSCs) need to be well encapsulated to improve long term stability. The most common method, glass-glass encapsulation, uses edge sealant materials to encapsulate the device between sheets of glass. Glass-Glass encapsulation, while providing provide adequate protection from the ambient environment, limits the use of flexible substrates for thin film solar cells due to its rigidity. Additionally, the added weight of glass encapsulation reduces the specific power (W kg−1) of PSCs, which is an important factor when designing solar cells for aerospace applications. Here we demonstrate that commercially available acrylic spray encapsulation offers efficient and robust stability for PSCs. It is shown that applying the encapsulation via this method does not degrade the PSCs, unlike other literature and glass-glass encapsulation methods. Additionaly, it is shown that 1 coat of acrylic spray encapsulation has an effective thickness of ∼1.77 µm and a weight of ∼6 mg. For stability measurements, PSCs with an acrylic coating show a 4% increase in performance after ∼730 h under dark storage conditions and retain 88% of their initial power conversion efficiency after 288 h under 85% relative humidity 25 °C. We anticipate our assay to be a starting point for further studies into spray encapsulation materials and methods not just for terrestial applications, but for aerospace applications as well

Perovskite photovoltaics for aerospace applications − life cycle assessment and cost analysis

In the past few years, we have witnessed a rapid evolution of perovskite solar cells. In this study, we employ life cycle assessment (LCA) to identify the potential environmental impacts of perovskite solar cells (PSC) optimised for aerospace applications but could be used in conventional terrestrial applications too. One PSC module is manufactured by spin coating equipped with ITO glass and gold cathode. The other PSC module is manufactured by slot-die coating with a PET layer and carbon cathode and gold cathode respectively. Life cycle assessment is employed to compare potential environmental impact of two manufacture methods by impact method of Recipe(H), as well as the fabrication cost of PSC module. The primary data of material and energy used for fabricating PSCs are collected from spin coating with lab scale and slot-die coating with pilot scale. The life cycle impact assessment of the PSC module in the pilot scale shows much lower in all the assessed 18 impact categories than in the lab scale thanks to the material use efficiency and reducing energy consumption. Gold as a conduct electrode has the highest impacts in both spin coating and slot-die coating modules. Calculating with a two-year lifetime (typical of aerospace applications), the impact of global warming potential from the PSC module with carbon electrode with pilot scale used in a terrestrial application is calculated to be 12 g/kWh

Development of a Selective Inhibitor for Kv1.1 Channels Prevalent in Demyelinated Nerves

Members of the voltage-gated K+ channel subfamily (Kv1), involved in regulating transmission between neurons or to muscles, are associated with human diseases and, thus, putative targets for neurotherapeutics. This applies especially to those containing Kv1.1 α subunits which become prevalent in murine demyelinated axons and appear abnormally at inter-nodes, underlying the perturbed propagation of nerve signals. To overcome this dysfunction, akin to the consequential debilitation in multiple sclerosis (MS), small inhibitors were sought that are selective for the culpable hyper-polarising K+ currents. Herein, we report a new semi-podand – compound 3 – that was designed based on the modelling of its interactions with the extracellular pore region in a deduced Kv1.1 channel structure. After synthesis, purification, and structural characterisation, compound 3 was found to potently (IC50 = 8 µM) and selectively block Kv1.1 and 1.6 channels. The tested compound showed no apparent effect on native Nav and Cav channels expressed in F-11 cells. Compound 3 also extensively and selectively inhibited MS-related Kv1.1 homomer but not the brain native Kv1.1- or 1.6-containing channels. These collective findings highlight the therapeutic potential of compound 3 to block currents mediated by Kv1.1 channels enriched in demyelinated central neurons

Radiation Hardness of Perovskite Solar Cells Based on Aluminum‐Doped Zinc Oxide Electrode Under Proton Irradiation

Due to their high specific power and potential to save both weight and stow volume, perovskite solar cells have gained increasing interest to be used for space applications. However, before they can be deployed into space, their resistance to ionizing radiations such as high‐energy protons must be demonstrated. In this report, we investigate the effect of 150 keV protons on the performance of perovskite solar cells based on aluminium‐doped zinc oxide (AZO) transparent conducting oxide (TCO). Record power conversion efficiency of 15% and 13.6% were obtained for cells based on AZO under AM1.5G and AM0 illumination, respectively. We demonstrate that perovskite solar cells can withstand proton irradiation up to 1013 protons.cm−2 without significant loss in efficiency. At this irradiation dose, Si or GaAs solar cells would be completely or severely degraded when exposed to 150 keV protons. From 1014 protons.cm−2, a decrease in short‐circuit current of the perovskite cells is observed, which is consistent with interfacial degradation due to deterioration of the Spiro‐OMeTAD HTL during proton irradiation. Using a combination of non‐destructive characterization techniques, results suggest that the structural and optical properties of perovskite remain intact up to high fluence levels. Although shallow trap states are induced by proton irradiation in perovskite bulk at low fluence levels, they can release charges efficiently and are not detrimental to the cell's performance. This work highlights the potential of perovskite solar cells based on AZO TCO to be used for space applications and give a deeper understanding of interfacial degradation due to proton irradiation