Reconfigurable multivariable control law for commercial airplane using a direct digital output feedback design

The ability of a pilot to reconfigure the control surfaces on an airplane after a failure, allowing the airplane to recover to a safe condition for landing, becomes more difficult with increasing airplane complexity. Techniques are needed to stabilize and control the airplane immediately after a failure, allowing the pilot time to make longer range decisions. This paper shows a design of a discrete multivariable control law using four controls for the longitudinal channel of a B-737. Single control element failures are allowed in three of the four controls. The four controls design and failure cases are analyzed by means of a digital airplane simulation, with regard to tracking capability and ability to overcome severe windshear and turbulence during the aproach and landing phase of flight

Application of variable-gain output feedback for high-alpha control

A variable-gain, optimal, discrete, output feedback design approach that is applied to a nonlinear flight regime is described. The flight regime covers a wide angle-of-attack range that includes stall and post stall. The paper includes brief descriptions of the variable-gain formulation, the discrete-control structure and flight equations used to apply the design approach, and the high performance airplane model used in the application. Both linear and nonlinear analysis are shown for a longitudinal four-model design case with angles of attack of 5, 15, 35, and 60 deg. Linear and nonlinear simulations are compared for a single-point longitudinal design at 60 deg angle of attack. Nonlinear simulations for the four-model, multi-mode, variable-gain design include a longitudinal pitch-up and pitch-down maneuver and high angle-of-attack regulation during a lateral maneuver

Cooperative game theory and its application to natural, environmental, and water resource issues : 3. application to water resources

This paper reviews various applications of cooperative game theory (CGT) to issues of water resources. With an increase in the competition over various water resources, the incidents of disputes have been in the center of allocation agreements. The paper reviews the cases of various water uses, such as multi-objective water projects, irrigation, groundwater, hydropower, urban water supply, wastewater, and transboundary water disputes. In addition to providing examples of cooperative solutions to allocation problems, the conclusion from this review suggests that cooperation over scarce water resources is possible under a variety of physical conditions and institutional arrangements. In particular, the various approaches for cost sharing and for allocation of physical water infrastructure and flow can serve as a basis for stable and efficient agreement, such that long-term investments in water projects are profitable and sustainable. The latter point is especially important, given recent developments in water policy in various countries and regional institutions such as the European Union (Water Framework Directive), calling for full cost recovery of investments and operation and maintenance in water projects. The CGT approaches discussed and demonstrated in this paper can provide a solid basis for finding possible and stable cost-sharing arrangements.Town Water Supply and Sanitation,Environmental Economics&Policies,Water Supply and Sanitation Governance and Institutions,Water Supply and Systems,Water and Industry

Command generator tracker based direct model reference adaptive control of a PUMA 560 manipulator

This project dealt with the application of a Direct Model Reference Adaptive Control algorithm to the control of a PUMA 560 Robotic Manipulator. This chapter will present some motivation for using Direct Model Reference Adaptive Control, followed by a brief historical review, the project goals, and a summary of the subsequent chapters

Transient analysis and control of a heat to power conversion unit based on a simple regenerative supercritical CO2 Joule-Brayton cycle

Supercritical carbon dioxide (sCO(2)) heat to power systems are a promising technology thanks to their potential for high efficiency and operational flexibility. However, their dynamic behaviour during part-load and transient operation is still not well understood and further research is needed. Additionally, there is not enough literature addressing suitable control approaches when the objective is to follow the dynamics of heat load supplied by the topping process to maximise the power recovery. The current research aims to fill these gaps by proposing a one-dimensional transient modelling formulation calibrated against the major components of a 50 kW(e) sCO(2) test facility available at Brunel University London. The dynamic analysis showed that the system quickly adapts to a 2800s transient heat load profile, proving the flexible nature of the sCO(2) system investigated. The turbine bypass, during startup and shutdown modes of operation, enabled gradual and safe build-up/decline of the pressures and temperatures throughout the loop. The regulation of the inventory in the range 20-60 kg allowed a 30% variation of the turbine inlet temperature with lower penalties on system performance than the turbomachinery speed control. The designed proportional-integral inventory controller showed a rapid response in the control of the turbine inlet temperature around the set point of 773 K during large variations of the heat load

Generating and evaluating salinity and temperature resilient cyanobacteria for tropical outdoor cultivation in Australia

Global population levels, anticipated to increase to >9 billion by 2050, present serious worldwide challenges, such as energy-, food- and freshwater security. In addition, rising greenhouse gas (GHG) emissions lead to climatic instability, reduce the availability of freshwater and challenge agricultural productivity, which is exacerbated by decreasing arable land availability. Hence, the carbon- and freshwater-constrained economy demands industries to limit freshwater usage and carbon emissions. In this context, photosynthetic microalgae or cyanobacteria offer great promise for remediating carbon-dioxide emissions and high-nutient wastewaters, which can be coupled with renewable resource production to cater for large-volume low-value markets, such as animal feed, bio-fertiliser, and energy-production. The required scale of production for these markets, however, has to date not been realised, as outdoor cultivation presents severe challenges, including access to sufficient non-arable land in close proximity to water, nutrients (inorganic fertilisers: nitrogen and phosphate) and carbon-dioxide sources. In addition, high temperature and variable salinities are major limitations to cost-effective commercial microalgal production, as these factors are challenging to control. Ectoine, a valuable osmolyte, is produced by extremophile microbes in response to variable salinities and high temperature stress. Ectoine synthesis is mediated by an ectABC gene cassette. Given this, my research aimed at engineering a de novo biosynthesis pathway for ectoine production into the freshwater cyanobacterium Synechococcus elongatus PCC 7942 - to examine: a) its effect on temperature and/or salinity tolerance and b) potential downstream effects of ectoine on fertilisation requirements and biochemical profiles of this cyanobacterium, as the latter affects bio-product potential. Synechococcus elongatus PCC7942 was chosen as a model cyanobacterium, as its genome is small and fully sequenced, commercial vectors for transformation are available and it is exempt from restriction of laboratory transformation experiments by the Office of Gene Technology Regulator (OGTR). For ectABC transformation of S. elongatus PCC7942, a codon-optimised ectABC_pSyn_6 plasmid was constructed, based on the ectABC gene nucleotide sequence from the temperature- and salinity-tolerant bacterium Halomonas elongata DSM4043. ectABC-transformed, untransformed pSyn_6 vector (lacking ectABC insert) controls and wild-type (no vector, WT) S. elongatus PCC 7942 were subjected to a three temperature (35, 40, and 45°C), three salinity (0, 18, 36 ppt) factorial design experimental challenge without acclimation. Our data confirmed that ectABC-transformed S. elongatus PCC7942 had improved temperature tolerance up to 45°C and salinity tolerance up to 18 ppt at 35°C, compared to WT and pSyn_6 empty vector controls. Limited growth was observed at 36 ppt salinity in WT, pSyn-6 and ectABC transformants, irrespective of temperature. ectABC-transformant population growth rates were highest at 35°C. High pressure liquid chromatography analysis of these ectABC transformants confirmed ectoine production, albeit minimal. Further studies are necessary at the molecular level to resolve impediments associated with the low level of ectoine expression, should ectoine be chosen as a high-value co-product for the cosmetics industry. In terms of commercial production, it is vital to assess ectABCtransformed S. elongatus PCC 7942 fertilisation requirements. Results showed that nitrogen-requirements of ectABC-transformants were higher than that of WT and pSyn_6 empty vector controls at an elevated salinity of 18 ppt, but lower at 45°C temperature stress. Phosphate uptake was lowest in ectABC-transformants at temperature and salinity stress of 45°C and 18 ppt, respectively. Fertilisation costs require serious consideration for commercial-scale cultivation of large-volume, low-value bio-products markets. Thus, the stress-induced increased nitrogen fertilisation requirements of ectABC-transformants suggest that co-location with nitrogen-rich wastewater streams would be beneficial, thereby also reducing nutrient run-off into the local river systems. Regarding the biochemical profile of hydrocarbon-based biofuel production, ectABC transformants had increased lipid and fatty acid production under both temperature (45°C) and salinity (18 ppt) stress. Thus, this research addresses an area of importance for transitioning to a bio‐economy as a whole and for implementing environmentally and economically sustainable production of renewable biofuels, animal feed, bio-fertilisers, which are perhaps best achieved through co-production of some high-value bio-products, such as ectoine or the high-value pigment - c-phycocyanin. To investigate this potential, a modelling approach using multi-criteria analysis and geographical information system analysis was adopted. ArcGIS was used to evaluate potential sites suitable for co‐locating microalgal and sugarcane production in the Great Barrier Reef (GBR) catchment region in Queensland, Australia – whilst taking into account climatic, land-use and economic factors that consider energy balances for each facility. Critical resource inputs such as land, water, CO₂, energy and climatic factors such as temperature and rainfall were considered when estimating the available resources at sugar mills in the Wet Tropics region, adjacent to the GBR. Our economic analysis revealed that co-locating microalgal biomass production with such an industry is economically feasible in the Wet Tropics, by achieving significant cost-reductions and improved economic performance. As such, this research produces valuable information for investors, policy makers, government and industry to make informed decisions about the location potential for microalgal production sites that focus on salinity and temperature-resilient microalgal cultivation for high-value compounds (e.g. the osmolyte ectoine) or low-value animal feed as their principal commodity, whilst reducing CO₂ emissions and nutrient runoff to the GBR, both of which attract tradeable credits which offer additional economic returns over and above the returns from the production and sales process

Application of broadband, time-resolved magneto-optics to problems in ultrafast photophysics

Ever faster computers require ever more efficient data storage technologies. A major bottleneck for faster data storage in magnetic media is the speed at which magnetisation can be manipulated. To circumvent this, a better understanding of magnetisation and magnetic materials on ultrashort timescales (10⁻¹⁵ − 10⁻⁹ s) is required. Pump-probe spectroscopy allows us to measure the response of systems to an optical stimulus over such times. When combined with magneto-optics, this provides a valuable method for investigating ultrafast magnetisation dynamics. A promising group of materials for future technologies is that of 2D materials, where the reduced dimensionality can cause them to have different properties to their 3D counterparts. Cᵣ₂Gₑ₂Tₑ₆ (CGT) is a recently discovered 2D ferromagnetic semiconductor which is a potential system for studying and understanding magnetism on ultrashort timescales. Transient ellipticity and transmittance spectra of a small, thin, single crystal of CGT were measured at 20 K , well below the Curie temperature of ∼63 K. Strong wavelength dependence was observed in the transient ellipticity spectrum, meaning that the ellipticity change was proportional to not only magnetisation change. The spectrum could be decomposed into the contributions arising from photoexcited electrons and demagnetisation, both of which showed very different dynamics. Magnetic fields in a medium influence the polarisation of transmitted light through magneto-optic phenomena. Most studies of ultrafast magnetism use only single wavelengths to probe samples, which can miss the vital information that broadband spectra can provide. I have therefore built a broadband, ultrafast spectrometer that can measure transient polarisation change with a 350–750 nm, 200 fs supercontinuum probe. Ellipticity change is measured through the change in transmittance of a circularly polarised probe pulse when an applied magnetic field is reversed. Similarly, the transient ellipticity change is found from the change in transient transmittance. Rotation can be measured in a similar manner. To compare performance relative to other published instruments and validate its correct operation, the spectrometer was tested on various samples, from ferromagnetic films to paramagnetic ions in solution. Porphyrins are organic, naturally occurring compounds which show rich ellipticity and absorbance spectra so their photophysics are well studied. Zinc tetraphenylporphyrin, a member of this family of compounds, shows a strong ellipticity spectrum at room temperature and undergoes intersystem crossing from singlet to triplet states upon photoexcitation. Ultrafast electronic changes may therefore result in transient changes to the ellipticity, which could be measured with the above setup and compared to the transient absorbance. Broadband ellipticity spectra of the complex in solution were measured and the transient depopulation of the ground state was observed through a signal with the same shape as the ground state ellipticity spectrum. Furthermore, transient ellipticity spectra whose dynamics corresponded to an excited singlet state could be observed