Planar Rayleigh scattering and laser-induced fluorescence for visualization of a hot, Mach 2 annular air jet

Planar Rayleigh scattering (PRS) and planar laser-induced fluorescence (PLIF) were used to investigate the vitiated air component of a coaxial hydrogen/vitiated air nonpremixed turbulent jet flame that is ejected at a Mach number of 2. All experiments were performed with a xenon chloride tunable excimer laser. Planar information for both techniques was obtained using laser sheets 6 cm high, 5 cm wide, and 300 micron thick. In this flow field, the effective Rayleigh cross section of the components in the vitiated air was assumed to be independent of composition. Therefore, the PRS technique produced signals which were proportional to total density. When the flow field was assumed to be at a known and uniform pressure, the PRS signal data for the vitiated air could be converted to temperature information. Also, PLIF images were generated by probing the OH molecule. These images contain striation patterns attributed to small localized instantaneous temperature nonuniformities. The results from the PLIF and PRS techniques were used to show that this flow field contains a nongaseous component, most likely liquid water that can be reduced by increasing the settling chamber wall temperature

Mach 10 Bow-Shock Unsteadiness Modeled by Linear Combination of Two Mechanisms

This manuscript presents mechanisms to explain and mathematics to model time-averaged spatially-resolved amplitude observations of number density and number density unsteadiness in a Mach 10 flow as it transitions from the freestream, through a bow shock wave, and into the gas cap created by a blunt-body model. The primary driver for bow shock unsteadiness is freestream unsteadiness or tunnel noise. Primary unsteadiness is bow shock oscillation. It scales spatially with number density first derivative and is modeled using a sech(sup 2) (z) term. Secondary weaker unsteadiness begins as freestream unsteadiness and increases linearly in direct proportion to gas number density across the bow shock and into the gas cap. This is the well-known amplification of freestream turbulent kinetic energy mechanism and is modeled using a tanh (z) term. Total unsteadiness (fit using tanh(z) term + sech2(z) term) is expressed as number density standard deviation and modeled as a linear combination of the latter two independent, simultaneous, and nonlinear unsteadiness mechanisms. Relationships between mechanism coefficients and various flow field and wind tunnel parameters are discussed. For example, bow shock and gas cap oscillation amplitudes are linearly correlated with stagnation pressure and by deduction freestream unsteadiness

Planar Rayleigh scattering results in helium-air mixing experiments in a Mach-6 wind tunnel

Planar Rayleigh scattering measurements with an argon—fluoride excimer laser are performed to investigate helium mixing into air at supersonic speeds. The capability of the Rayleigh scattering technique for flow visualization of a turbulent environment is demonstrated in a large-scale, Mach-6 facility. The detection limit obtained with the present setup indicates that planar, quantitative measurements of density can be made over a large cross-sectional area (5 cm × 10 cm) of the flow field in the absence of clusters

Signal Analysis Algorithms for Optimized Fitting of Nonresonant Laser Induced Thermal Acoustics Damped Sinusoids

This study seeks a numerical algorithm which optimizes frequency precision for the damped sinusoids generated by the nonresonant LITA technique. It compares computed frequencies, frequency errors, and fit errors obtained using five primary signal analysis methods. Using variations on different algorithms within each primary method, results from 73 fits are presented. Best results are obtained using an AutoRegressive method. Compared to previous results using Prony s method, single shot waveform frequencies are reduced approx.0.4% and frequency errors are reduced by a factor of approx.20 at 303K to approx. 0.1%. We explore the advantages of high waveform sample rates and potential for measurements in low density gases

Rayleigh Scattering Density Measurements, Cluster Theory, and Nucleation Calculations at Mach 10

In an exploratory investigation, quantitative unclustered laser Rayleigh scattering measurements of density were performed in the air in the NASA Langley Research Center's 31 in. Mach 10 wind tunnel. A review of 20 previous years of data in supersonic and Mach 6 hypersonic flows is presented where clustered signals typically overwhelmed molecular signals. A review of nucleation theory and accompanying nucleation calculations are also provided to interpret the current observed lack of clustering. Data were acquired at a fixed stagnation temperature near 990Kat five stagnation pressures spanning 2.41 to 10.0 MPa (350 to 1454 psi) using a pulsed argon fluoride excimer laser and double-intensified charge-coupled device camera. Data averaged over 371 images and 210 pixels along a 36.7mmline measured freestream densities that agree with computed isentropic-expansion densities to less than 2% and less than 6% at the highest and lowest densities, respectively. Cluster-free Mach 10 results are compared with previous clustered Mach 6 and condensation-free Mach 14 results. Evidence is presented indicating vibrationally excited oxygen and nitrogen molecules are absorbed as the clusters form, release their excess energy, and inhibit or possibly reverse the clustering process. Implications for delaying clustering and condensation onset in hypersonic and hypervelocity facilities are discussed

Cultura do girassol: tecnologia de produção.

Escolha de area e preparo do solo; Correcao da acidez; Adubacao; Epoca de plantio; Plantio; Densidade; Controle de plantas daninhas; Doencas e pragas; Colheita.bitstream/item/61288/1/Documentos-67-1996.pdf2. ed. rev. aum

Cultura do girassol: tecnologia de produção.

Escolha da area e preparo do solo; Correcao da acidez; Adubacao; Epoca de plantio; Plantio; Densidade; Controle de plantas daninhas; Doencas e pragas; Colheita.bitstream/item/60796/1/Documentos-67.pd

Label-Free Characterization of Cancer-Activated Fibroblasts Using Infrared Spectroscopic Imaging

AbstractGlandular tumors arising in epithelial cells comprise the majority of solid human cancers. Glands are supported by stroma, which is activated in the proximity of a tumor. Activated stroma is often characterized by the molecular expression of α-smooth muscle actin (α-SMA) within fibroblasts. However, the precise spatial and temporal evolution of chemical changes in fibroblasts upon epithelial tumor signaling is poorly understood. Here we report a label-free method to characterize fibroblast changes by using Fourier transform infrared spectroscopic imaging and comparing spectra with α-SMA expression in primary normal human fibroblasts. We recorded the fibroblast activation process by spectroscopic imaging using increasingly tissue-like conditions: 1), stimulation with the growth factor TGFβ1; 2), coculture with MCF-7 human breast cancerous epithelial cells in Transwell coculture; and 3), coculture with MCF-7 in three-dimensional cell culture. Finally, we compared the spectral signatures of stromal transformation with normal and malignant human breast tissue biopsies. The results indicate that this approach reveals temporally complex spectral changes and thus provides a richer assessment than simple molecular imaging based on α-SMA expression. Some changes are conserved across culture conditions and in human tissue, providing a label-free method to monitor stromal transformations

Laser Rayleigh Scattering for Flow Density and Condensation Measurements in the Supercooled Mach-14 Free-Stream at AEDC Wind Tunnel No. 9

Laser Rayleigh scattering was used to investigate clusters in the free-stream flow at Arnold Engineering Development Centers Tunnel 9 (T9). The facility was run at Mach-14, with a pure-N2 flow medium, and at several total pressures and temperatures. Using an excimer laser operating at 248 nm, the Rayleigh instrument imaged scattering from the focused laser beam in the free-stream. As a wind-tunnel flow is accelerated, it cools and approaches the condensation boundary. As a precursor to condensation, small clusters of molecules are first formed, but the individual clusters are too small to be spatially resolved in typical images of the beam. Thus clusters effectively add a spatially smooth background signal to the pure diatomic-molecule Rayleigh signal. The main result of the present work is that clustering was not significant. After correcting for interference by small particles imbedded in the T9 flow, cluster scattering was unobservable or smaller than one standard deviation (1-sigma) of the uncertainties for almost all tunnel runs. The total light scattering level was measured to be 1.05 +/- 0.15 (1-sigma) of the expected diatomic scattering, when averaged over the entire usable data set. This result included flow conditions that were supercooled to temperatures of ~ 20 K, about 25 K below the condensation limit of ~ 45 K. Thus the Mach-14 nozzle flow is essentially cluster-free for many supercooled conditions that might be used to extend the facility operating range to larger Reynolds numbers

Does Nepal’s Climate Change Adaptation Policy and Practices Address Poor and Vulnerable Communities?

Climate change (CC) impact, adaptation practices and policies are an emerging area of research and development in Nepal. Many households were deeply affected by, climatic variability and natural disasters coupled with a decade-long conflict, leaving them with few options to cope with CC in Nepal. The study was done through reviewed CC related policies and programs initiated at the national to local level.  Additionally, study was conducted to analyze different CC adaptation programs and practices in different eco-region from Himalaya to Inner Terai region of center and western Nepal through shared learning dialogue, field observation, key informant interview, regional and district level consultative workshop and focus group discussion. To address the issues of CC, different government and nongovernment institutions have initiated its adaptation programs in Nepal. NAPA and LAPA- Nepal highlighted the adaptation practices and adaptation framework from national to local level. These national programs initiatives have been endorsed by the GoN (Government of Nepal) through the promulgation of CC Policy Nepal 2011.  The policy has focused on interdisciplinary approach with 80% funds allocated at the local level particularly for poor and vulnerable groups. Some district level offices have initiated CC adaptation activities such as construction of water harvesting pond for irrigation, water source protection, agroforestry practices and training on CC adaptation and mitigation. Similarly, in some project supported districts, community level and VDC level five year local adaptation plans have been prepared. However, it is observed that there is a big gap in institutional arrangement, capacity to implement and mechanisms for adaptation programs at local level and poor communities. It was also observed that different GOs programs and NGOs were involved to improve the livelihood of the poor and vulnerable communities through pro-poor programs at local level which resulted improve CC adaptation capacity. It is suggested that CC policy in Nepal be formulated with holistic approach, institutionalized implementing mechanism and focus on livelihood improvement of the poor and vulnerable communities that have joint environmental, social or economic benefits. Keywords:  Community, Institutions, NAPA, no-regret approach, LAPA, Livelihood, Vulnerabilit