X-ray and Laser Investigation of High Pressure Sprays

The diagnostics of multiphase flows is important to understand the correlation of parameters such as nozzle geometry, flow velocity, liquid breakup characteristics, atomization, and mass distribution. Investigation of each of these parameters can lead to various improvements on design and optimization, for example, of combustion in gas turbines and rocket engines. For this project, the X-ray and optical diagnostics of multiphase flows in propulsion is investigated for high pressures. Two x-ray tube sources are used to illuminate the spray, and the images are captured on phosphor plates coupled to high-speed cameras. Reconstruction of the mass distribution is accomplished using computer analysis by applying Beer’s-Lambert law. High temporal resolution and spatial resolution images were collected of various sprays composed of water and KI solutions for development and characterization of the technique with different window materials typically used in high-pressure vessels. Laser-based fluorescence was tested in vaporized jet-A fuel in a high-pressure vessels. The implications for X-ray and laser analysis of multiphase flows in sprays with high spatial and temporal resolution and high signal to noise ratio are investigated

Optimization of a High-Speed X-Ray Imaging System for Studying Sprays

Spray-based liquid atomization and liquid mixing is critical for development of efficient combustors and drug delivery systems as well as multiple coating-related applications. While optical methods allow characterization of low density regions of sprays, the scattering of optical photons hinders the characterization of a dense core. Unlike optical photons, higher-energy X-ray photons have the capability to penetrate and image the core structure of sprays. Here we characterized temporal and spatial resolution of an X-Ray imaging system based on a commercially available tube source with an anode size of 0.6 mm. For high-speed imaging, a phosphor screen in combination with a high-speed CMOS camera equipped with a two-stage intensifier was used. Water was used as a model liquid with the addition of potassium iodide to increase the X-Ray absorption coefficient. Two-dimensional images of 0.5mm and 2 mm impinging jet sprays were taken with differing spatial resolutions and potassium iodide mass concentrations. Depending on the spray conditions, optimal imaging settings were found. The technique can be extended to three-dimensional analysis of sprays with multiple viewing angles from two or more X-ray sources along with tomographic reconstruction

Current status and perceived needs of information technology in Critical Access Hospitals: a survey study

The US Congress established the designation of Critical Access Hospitals in 1997, recognising rural hospitals as vital links to health for rural and underserved populations. The intent of the reimbursement system is to improve financial performance, thereby reducing hospital closures. Informatics applications are thought to be tools that can enable the sustainability of such facilities. The aim of this study is to identify the current use of information and communication technology in Critical Access Hospitals, and to assess their readiness and receptiveness for the use of new software and hardware applications and their perceived information technology (IT) needs. A survey was mailed to the administrators of all Critical Access Hospitals in one US state (Missouri) and a reminder was mailed a few weeks later. Twenty-seven out of 33 surveys were filled out and returned (response rate 82%). While most respondents (66.7%) stated that their employees have been somewhat comfortable in using new technology, almost 15% stated that their employees have been somewhat uncomfortable. Similarly, almost 12% of the respondents stated that they themselves felt somewhat uncomfortable introducing new technology. While all facilities have computers, only half of them have a specific IT plan. Findings indicate that Critical Access Hospitals are often struggling with lack of resources and specific applications that address their needs. However, it is widely recognised that IT plays an essential role in the sustainability of their organisations. The study demonstrates that IT applications have to be customised to address the needs and infrastructure of the rural settings in order to be accepted and properly utilised

Effects of high temperature annealing on single crystal ZnO and ZnO devices

We have systematically investigated the effects of high-temperature annealing on ZnO and ZnO devices using current voltage, deep level transient spectroscopy (DLTS) and Laplace DLTS measurements. Current–voltage measurements reveal the decrease in the quality of devices fabricated on the annealed samples, with the high-temperature annealed samples yielding devices with low barrier heights and high reverse currents. DLTS results indicate the presence of three prominent defects in the as-received samples. Annealing the ZnO samples at 300 C, 500 C, and 600 C in Ar results in an increase in reverse leakage current of the Schottky contacts and an introduction of a new broad peak. After 700 C annealing, the broad peak is no longer present, but a new defect with an activation enthalpy of 0.18 eV is observed. Further annealing of the samples in oxygen after Ar annealing causes an increase in intensity of the broad peak. High-resolution Laplace DLTS has been successfully employed to resolve the closely spaced energy levels.The South African National Research Foundation (NRF), A. R. Peaker (Centre for Electronic Materials Devices and Nanostructures, University of Manchester) and L. Dobaczewski (Institute of Physics, Polish Academy of Sciences).http://jap.aip.org/nf201

Application of a spring-dashpot system to clinical lung tumor motion data

A spring-dashpot system based on the Voigt model was developed to model the correlation between abdominal respiratory motion and tumor motion during lung radiotherapy. The model was applied to clinical data comprising 52 treatment beams from 10 patients, treated on the Mitsubishi Real-Time Radiation Therapy system, Sapporo, Japan. In Stage 1, model parameters were optimized for individual patients and beams to determine reference values and to investigate how well the model can describe the data. In Stage 2, for each patient the optimal parameters determined for a single beam were applied to data from other beams to investigate whether a beam-specific set of model parameters is sufficient to model tumor motion over a course of treatment. In Stage 1 the baseline root mean square (RMS) residual error for all individually-optimized beam data was 0.90 plus or minus 0.40 mm. In Stage 2, patient-specific model parameters based on a single beam were found to model the tumor position closely, even for irregular beam data, with a mean increase with respect to Stage 1 values in RMS error of 0.37 mm. On average the obtained model output for the tumor position was 95% of the time within an absolute bound of 2.0 mm and 2.6 mm in Stage 1 and 2, respectively. The model was capable of dealing with baseline, amplitude and frequency variations of the input data, as well as phase shifts between the input tumor and output abdominal signals. These results indicate that it may be feasible to collect patient-specific model parameters during or prior to the first treatment, and then retain these for the rest of the treatment period. The model has potential for clinical application during radiotherapy treatment of lung tumors

Validation of an all-sky imager based nowcasting system for industrial PV plants

Because of the cloud-induced variability of the solar resource, the growing contributions of photovoltaic plants to the overall power generation challenges the stability of electricity grids. To avoid blackouts, administrations started to define maximum negative ramp rates. Storages can be used to reduce the occurring ramps. Their required capacity, durability, and costs can be optimized by nowcasting systems. Nowcasting systems use the input of upward-facing cameras to predict future irradiances. Previously, many nowcasting systems were developed and validated. However, these validations did not consider aggregation effects, which are present in industrial-sized power plants. In this paper, we present the validation of nowcasted global horizontal irradiance (GHI) and direct normal irradiance maps derived from an example system consisting of 4 all-sky cameras (“WobaS-4cam”). The WobaS-4cam system is operational at 2 solar energy research centers and at a commercial 50-MW solar power plant. Besides its validation on 30 days, the working principle is briefly explained. The forecasting deviations are investigated with a focus on temporal and spatial aggregation effects. The validation found that spatial and temporal aggregations significantly improve forecast accuracies: Spatial aggregation reduces the relative root mean square error (GHI) from 30.9% (considering field sizes of 25 m2) to 23.5% (considering a field size of 4 km2) on a day with variable conditions for 1 minute averages and a lead time of 15 minutes. Over 30 days of validation, a relative root mean square error (GHI) of 20.4% for the next 15 minutes is observed at pixel basis (25 m2). Although the deviations of nowcasting systems strongly depend on the validation period and the specific weather conditions, the WobaS-4cam system is considered to be at least state of the art