New methods and results in the optimisation of solar power tower plants

Renewable energy technology has seen great advances in recent decades, combined with an ever increasing interest in the literature. Solar Power Tower (SPT) plants are a form of Concentrating Solar Power (CSP) technology which continue to be developed around the world, and are formed of subsystems that are open to optimisation. This thesis is concerned with the development of new methods and results in the optimisation of SPT plants, with particular focus on operational optimi- sation. Chapter 1 provides background information on the energy sector, before describing the design and modelling of an SPT plant. Here, the optical theory behind the transfer of incident radiation in the system is developed and the relevant equations presented. In Chapter 2, the cleaning operations of the heliostat eld are optimised for a xed schedule length using Binary Integer Linear Programming (BILP). Problem dimensionality is addressed by a clustering algorithm, before an ini- tial solution is found for the allocation problem. Finally, a novel local search heuristic is presented that treats the so-called route \attractiveness" through the use of a sequential pair-wise optimisation procedure that minimises a weighted attractiveness measure whilst penalising for overall energy loss. Chapters 3-6 investigate the aiming strategy utilised by the heliostat eld when considering a desired ux distribution pro le and operational constraints. In Chapter 3, a BILP model was developed, where a pre-de ned set of aim- ing points on the receiver surface was chosen. The linear objective function was constrained with linear equalities that related to distribution smoothing (to pro- tect receiver components from abnormal ux loads) via the use of penalisation. Chapter 4 extended this model by instead considering continuous variables with no xed grid of aiming points. This led to an optimisation problem with a non- linear, non-convex objective function, with non-linear constraints. In this case, a gradient ascent algorithm was developed, utilising a non-standard step-size selection technique. Chapter 5 further extended the aiming point optimisation topic to consider the dynamic case. In this sense, the aiming strategy across a period of time could be optimised, taking into account SPT plant technologi- cal limitations. Two algorithms were considered, Penalisation and Augmented Lagrangian, where theoretical properties for optimality and solution existence were presented. Finally Chapter 6 considered the efects of inclement weather on the optimisation model presented in Chapter 3. Stochastic processes were in- vestigated to determine optimal aiming strategies at a xed point in time when weather data could not be known for certain. All research presented in this thesis is illustrated using real-world data for an SPT plant, and conclusions and recommendations for future work are presented

Heliostat field cleaning scheduling for Solar Power Tower plants: a heuristic approach

Soiling of heliostat surfaces due to local climate has a direct impact on their optical efficiency and therefore a direct impact on the productivity of the Solar Power Tower plant. Cleaning techniques applied are dependent on plant construction and current schedules are normally developed considering heliostat layout patterns, providing sub-optimal results. In this paper, a method to optimise cleaning schedules is developed, with the objective of maximising energy generated by the plant. First, an algorithm finds a cleaning schedule by solving an integer program, which is then used as a starting solution in an exchange heuristic. Since the optimisation problems are of large size, a p-median type heuristic is performed to reduce the problem dimensionality by clustering heliostats into groups to be cleaned in the same period.Ministerio de Economía y Competitivida

Chiminey: Reliable Computing and Data Management Platform in the Cloud

The enabling of scientific experiments that are embarrassingly parallel, long running and data-intensive into a cloud-based execution environment is a desirable, though complex undertaking for many researchers. The management of such virtual environments is cumbersome and not necessarily within the core skill set for scientists and engineers. We present here Chiminey, a software platform that enables researchers to (i) run applications on both traditional high-performance computing and cloud-based computing infrastructures, (ii) handle failure during execution, (iii) curate and visualise execution outputs, (iv) share such data with collaborators or the public, and (v) search for publicly available data.Comment: Preprint, ICSE 201

Groundwater Laws and Regulations: Survey of Sixteen U.S. States

This report is the second volume in a continuing project designed to explore and articulate the groundwater laws and regulations of all fifty U.S. states. This particular report presents surveys for sixteen states throughout the country. The first volume featured thirteen state surveys and can be found at: http://www.law.tamu.edu/usgroundwaterlaws. The purpose of the project is to compile and present the groundwater laws and regulations of every state in the United States that could then be used in a series of comparisons of groundwater governance principles, strategies, issues, and challenges. Professor Gabriel Eckstein at Texas A&M University School of Law and Professor Amy Hardberger at Texas Tech University School of Law developed a matrix to ascertain chief components and characteristics of the groundwater legal regime of each state. Student researchers then used the matrix to respond to a standardized set of questions about the groundwater laws and regulations of a selection of states. In the near future, additional volumes with surveys of the remaining twenty-one U.S. states will be issued

Latewood Ring Width Reveals CE 1734 Felling Dates for Walker House Timbers In Tupelo, Mississippi, USA

Dendroarchaeology is under-represented in the Gulf Coastal Plain region of the United States (US), and at present, only three published studies have precision dated a collection of 18th–19th-century structures. In this study, we examined the tree-ring data from pine, poplar, and oak timbers used in the Walker House in Tupelo, Mississippi. The Walker House was constructed ca. the mid-1800s with timbers that appeared to be recycled from previous structures. In total, we examined 30 samples (16 pines, 8 oaks, and 6 poplars) from the attic and crawlspace. We cross-dated latewood ring growth from the attic pine samples to the period 1541–1734 (r = 0.52, t = 8.43, p \u3c 0.0001) using a 514-year longleaf pine (Pinus palustris Mill.) latewood reference chronology from southern Mississippi. The crawlspace oak samples produced a 57-year chronology that we dated against a white oak (Quercus alba L.) reference chronology from northeast Alabama to the period 1765–1822 (r = 0.36, t = 2.83, p \u3c 0.01). We were unable to cross-date the six poplar samples due to a lack of poplar reference chronologies in the region. Our findings have two important implications: (1) the pine material dated to 1734 represents the oldest dendroarchaeology-confirmed dating match for construction materials in the southeastern US, and (2) cross-dating latewood growth for southeastern US pine species produced statistically significant results, whereas total ring width failed to produce significant dating results

Сахар из можжевеловой ягоды: [брошюра]

0|3|Сахар из можжевеловой ягоды [c. 3]0|7|Инструкция по сбору, сушке и хранению можжевеловой ягоды [c. 7]0|8|Инструкция по переработке можжевеловой ягоды на сладкие экстракты и сироп для школ, госпиталей, столовых и домашнего быта [c. 8]0|11|Использование экстракта и сиропа [c. 11

Updated Parameters and a New Transmission Spectrum of HD 97658b

Recent years have seen increasing interest in the characterization of sub-Neptune-sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD 97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four Hubble Space Telescope transits, 12 Spitzer/IRAC transits, and eight MOST transits of this system. Our transmission spectrum has a higher signal-to-noise ratio than those from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1–1.7 μm reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are inconclusive, as no model provides an excellent match to our data. Nonetheless, we find that atmospheres with high C/O ratios (C/O ≳ 0.8) and metallicities of ≳100× solar metallicity are favored. We combine the mid-transit times from all of the new Spitzer and MOST observations and obtain an updated orbital period of P = 9.489295 ± 0.000005, with a best-fit transit time center at T₀ = 2456361.80690 ± 0.00038 (BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34 ± 2 days) and stellar activity cycle (9.6 yr) of the host star HD 97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000 K and with sizes between 1 R⊕ and 4 R⊕. We find that at least a third of small planets cooler than 1000 K can be well characterized using James Webb Space Telescope, and of those, HD 97658b is ranked fifth, meaning that it remains a high-priority target for atmospheric characterization

Structure of the first representative of Pfam family PF04016 (DUF364) reveals enolase and Rossmann-like folds that combine to form a unique active site with a possible role in heavy-metal chelation.

The crystal structure of Dhaf4260 from Desulfitobacterium hafniense DCB-2 was determined by single-wavelength anomalous diffraction (SAD) to a resolution of 2.01 Å using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). This protein structure is the first representative of the PF04016 (DUF364) Pfam family and reveals a novel combination of two well known domains (an enolase N-terminal-like fold followed by a Rossmann-like domain). Structural and bioinformatic analyses reveal partial similarities to Rossmann-like methyltransferases, with residues from the enolase-like fold combining to form a unique active site that is likely to be involved in the condensation or hydrolysis of molecules implicated in the synthesis of flavins, pterins or other siderophores. The genome context of Dhaf4260 and homologs additionally supports a role in heavy-metal chelation

Structure of the γ-D-glutamyl-L-diamino acid endopeptidase YkfC from Bacillus cereus in complex with L-Ala-γ-D-Glu: insights into substrate recognition by NlpC/P60 cysteine peptidases.

Dipeptidyl-peptidase VI from Bacillus sphaericus and YkfC from Bacillus subtilis have both previously been characterized as highly specific γ-D-glutamyl-L-diamino acid endopeptidases. The crystal structure of a YkfC ortholog from Bacillus cereus (BcYkfC) at 1.8 Å resolution revealed that it contains two N-terminal bacterial SH3 (SH3b) domains in addition to the C-terminal catalytic NlpC/P60 domain that is ubiquitous in the very large family of cell-wall-related cysteine peptidases. A bound reaction product (L-Ala-γ-D-Glu) enabled the identification of conserved sequence and structural signatures for recognition of L-Ala and γ-D-Glu and, therefore, provides a clear framework for understanding the substrate specificity observed in dipeptidyl-peptidase VI, YkfC and other NlpC/P60 domains in general. The first SH3b domain plays an important role in defining substrate specificity by contributing to the formation of the active site, such that only murein peptides with a free N-terminal alanine are allowed. A conserved tyrosine in the SH3b domain of the YkfC subfamily is correlated with the presence of a conserved acidic residue in the NlpC/P60 domain and both residues interact with the free amine group of the alanine. This structural feature allows the definition of a subfamily of NlpC/P60 enzymes with the same N-terminal substrate requirements, including a previously characterized cyanobacterial L-alanine-γ-D-glutamate endopeptidase that contains the two key components (an NlpC/P60 domain attached to an SH3b domain) for assembly of a YkfC-like active site