A controlled migration genetic algorithm operator for hardware-in-the-loop experimentation

In this paper, we describe the development of an extended migration operator, which combats the negative effects of noise on the effective search capabilities of genetic algorithms. The research is motivated by the need to minimize the num- ber of evaluations during hardware-in-the-loop experimentation, which can carry a significant cost penalty in terms of time or financial expense. The authors build on previous research, where convergence for search methods such as Simulated Annealing and Variable Neighbourhood search was accelerated by the implementation of an adaptive decision support operator. This methodology was found to be effective in searching noisy data surfaces. Providing that noise is not too significant, Genetic Al- gorithms can prove even more effective guiding experimentation. It will be shown that with the introduction of a Controlled Migration operator into the GA heuristic, data, which repre- sents a significant signal-to-noise ratio, can be searched with significant beneficial effects on the efficiency of hardware-in-the- loop experimentation, without a priori parameter tuning. The method is tested on an engine-in-the-loop experimental example, and shown to bring significant performance benefits

Multi-Temporal InSAR Structural Damage Assessment: The London Crossrail Case Study

Spaceborne multi-temporal interferometric synthetic aperture radar (MT-InSAR) is a monitoring technique capable of extracting line of sight (LOS) cumulative surface displacement measurements with millimeter accuracy. Several improvements in the techniques and datasets quality lead to more effective, near real time assessment and response, and a greater ability of constraining dynamically changing physical processes. Using examples of the COSMO-SkyMed (CSK) system, we present a methodology that bridges the gaps between MT-InSAR and the relative stiffness method for tunnel-induced subsidence damage assessment. The results allow quantification of the effect of the building on the settlement profile. As expected the greenfield deformation assessment tends to provide a conservative estimate in the majority of cases (~ 71% of the analyzed buildings), overestimating tensile strains up to 50%. With this work we show how these two techniques in the field of remote sensing and structural engineering can be synergistically used to complement and replace the traditional ground based analysis by providing an extended coverage and a temporally dense set of data

Examination of Parent Insurance Ratings, Child Expenditures, and Financial Burden Among Children With Autism: A Mismatch Suggests New Hypotheses to Test

Families raising children with autism contribute significant amounts to the cost of care. In this era of health care reform, families have more insurance choices, but people are unfamiliar with health insurance terms. This study uses 2 national data sets to examine health insurance ratings from parents raising children with autism and child expenditures to explore how these measures align

Complications after pancreatic resection: diagnosis, prevention and management

BACKGROUND: Although mortality after pancreaticoduodenectomy (PD) or distal pancreatectomy (DP) has decreased, morbidity still remains high. The aim of this review article is to present, define, predict, prevent, and manage the main complications after pancreatic resection (PR). METHODS: A non-systematic literature search on morbidity and mortality after PR was undertaken using the PubMed/MEDLINE and Embase databases. RESULTS: The main complications after PR are delayed gastric emptying (DGE), pancreatic fistula (PF), and bleeding, as defined by the International Study Group on Pancreatic Surgery. PF occurs in 10% to 15% of patients after PD and in 10% to 30% of patients after DP. The different techniques of pancreatic anastomosis and pancreatic remnant closure do not show significant advantages in the prevention of PF, nor does the perioperative use of somatostatin and its analogues. The trend is for conservative or interventional radiology therapy for PF (with enteral nutrition), which achieves a success rate of approximately 80%. DGE after PD occurs in 20% to 50% of patients. Prophylactic erythromycin may reduce the incidence of DGE. Gastric aspiration with erythromycin is usually effective in one to three weeks. Bleeding (gastrointestinal and intraabdominal) occurs in 4% to 16% of patients after PD and in 2% to 3% of patients after DP. Endovascular treatment can only be used for a haemodynamically stable patient. In cases of haemodynamic instability or associated septic complications, surgical treatment is necessary. In expert centres, the mortality rates can be less than 1% after DP and less than 3% after PD. CONCLUSION: There is a need for improved strategies to prevent and treat complications after PR

Evaluation of a liquid chromatographic method for the determination of fumonisins in corn, poultry feed, and Fusarium culture material.

The performance of a liquid chromatographic method for determining fumonisins in corn, animal feeds, and culture material was evaluated. Efficiencies of extractions with the following solvent systems were determined: acetonitrile-water (50 + 50, v/v), methanol-water (75 + 25, v/v), and 100% water. The acetonitrile solvent gave both higher extraction efficiencies and faster extraction times than the other 2 solvents. Extraction was followed by C18 solid-phase extraction column cleanup. Fumonisin B1 (FB1), fumonisin B2 (FB2), and fumonisin B3 (FB3) were measured by precolumn derivatization with o-phthalaldehyde followed by isocratic separation on a C18 reversed-phase column with a mobile phase of 50 mM potassium dihydrogen phosphate (pH 3.3)-acetonitrile (60 + 40). Commercially prepared poultry feed, corn, and Fusarium spp. corn cultures were analyzed at the following levels: FB1, 1.5 to 15,000 micrograms/g; FB2, 0.5 to 4000 micrograms/g; FB3, and 0.17 to 1,500 micrograms/g. Recoveries were 91-94%, 90-100%, and 81-93% for FB1, FB2, and FB3, respectively. Precision (coefficient of variation) was determined with pooled field samples and ranged from 2% at 19 micrograms/g for FB1 to 9% at 0.17 microgram/g for FB3. Time and pH studies of the formation of the fluorescent derivative and its stability were conducted. Complete reaction occurred at pHs above 7.9, with optimal pH for chromatography between 8.0 and 8.5. No statistically significant response differences were detected for reaction times ranging from 4 to 40 min; however, the detector signal was significantly reduced when reaction times were shorter than 4 min. Chromatograms of samples were free of interferences for all feeds, corn, and culture material teste

Space construction system analysis. Part 2: Platform definition

The top level system requirements are summarized and the accompanying conceptual design for an engineering and technology verification platform (ETVP) system is presented. An encompassing statement of the system objectives which drive the system requirements is presented and the major mission and subsystem requirements are described with emphasis on the advanced communications technology mission payload. The platform design is defined and used as a reference configuration for an end to space construction analyses. The preferred construction methods and processes, the important interactions between the platform design and the construction system design and operation, and the technology development efforts required to support the design and space construction of the ETVP are outlined

A combined Eulerian-Lagrangian two-phase analysis of the SSME HPOTP nozzle plug trajectories

As a result of high cycle fatigue, hydrogen embrittlement, and extended engine use, it was observed in testing that the trailing edge on the first stage nozzle plug in the High Pressure Oxygen Turbopump (HPOTP) could detach. The objective was to predict the trajectories followed by particles exiting the turbine. Experiments had shown that the heat exchanger soils, which lie downstream of the turbine, would be ruptured by particles traveling in the order of 360 ft/sec. An axisymmetric solution of the flow was obtained from the work of Lin et. al., who used INS3D to obtain the solution. The particle trajectories were obtained using the method of de Jong et. al., which employs Lagrangian tracking of the particle through the Eulerian flow field. The collision parameters were obtained from experiments conducted by Rocketdyne using problem specific alloys, speeds, and projectile geometries. A complete 3-D analysis using the most likely collision parameters shows maximum particle velocities of 200 ft/sec. in the heat exchanger region. Subsequent to this analysis, an engine level test was conducted in which seven particles passed through the turbine but no damage was observed on the heat exchanger coils

Energy-resolved electron-spin dynamics at surfaces of p-doped GaAs

Electron-spin relaxation at different surfaces of p-doped GaAs is investigated by means of spin, time and energy resolved 2-photon photoemission. These results are contrasted with bulk results obtained by time-resolved Faraday rotation measurements as well as calculations of the Bir-Aronov-Pikus spin-flip mechanism. Due to the reduced hole density in the band bending region at the (100) surface the spin-relaxation time increases over two orders of magnitude towards lower energies. At the flat-band (011) surface a constant spin relaxation time in agreement with our measurements and calculations for bulk GaAs is obtained.Comment: 6 pages, 4 figure

Report on New Mission Concept Study: Stereo X-Ray Corona Imager Mission

Studies of the three-dimensional structure and dynamics of the solar corona have been severely limited by the constraint of single viewpoint observations. The Stereo X-Ray Coronal Imager (SXCI) mission will send a single instrument, an X-ray telescope, into deep space expressly to record stereoscopic images of the solar corona. The SXCI spacecraft will be inserted into a approximately 1 AU heliocentric orbit leading Earth by approximately 25 deg at the end of nine months. The SXCI X-ray telescope forms one element of a stereo pair, the second element being an identical X-ray telescope in Earth orbit placed there as part of the NOAA GOES program. X-ray emission is a powerful diagnostic of the corona and its magnetic fields, and three dimensional information on the coronal magnetic structure would be obtained by combining the data from the two X-ray telescopes. This information can be used to address the major solar physics questions of (1) what causes explosive coronal events such as coronal mass ejections (CMEs), eruptive flares and prominence eruptions and (2) what causes the transient heating of coronal loops. Stereoscopic views of the optically thin corona will resolve some ambiguities inherent in single line-of-sight observations. Triangulation gives 3D solar coordinates of features which can be seen in the simultaneous images from both telescopes. As part of this study, tools were developed for determining the 3D geometry of coronal features using triangulation. Advanced technologies for visualization and analysis of stereo images were tested. Results of mission and spacecraft studies are also reported

An integrated modelling approach for the seismic collapse assessment of masonry towers

Failure of tall slender masonry structures during earthquakes often involves partial collapse of the structure well-above ground level. Consequently, the elastic response of the structure needs to be considered, which often requires modal analysis using finite element models — the generation of which can be labour-intensive and time-consuming. This paper presents a new integrated modelling approach which combines finite element analysis with rocking dynamics to model the seismic response of complex structural geometries in a computationally-efficient manner. The modelling strategy is implemented within the open-source computational framework COMPAS and is incorporated within the broader framework of a tool being developed for the seismic collapse assessment of masonry structures. The framework of this tool is first outlined, and the utility of the new modelling approach then demonstrated through application to the seismic assessment of a three historic masonry towers in North-Eastern Italy. The importance of accounting for elastic amplification effects, as well as the influence of varying boundary conditions on the dynamic response, is also illustrated