Toward comparing experiment and theory for corroborative research on hingeless rotor stability in forward flight

For flap lag stability of isolated rotors, experimental and analytical investigations were conducted in hover and forward flight on the adequacy of a linear quasisteady aerodynamics theory with dynamic flow. Forward flight effects on lag regressing mode were emphasized. A soft inplane hingeless rotor with three blades was tested at advance ratios as high as 0.55 and at shaft angles as high as 20 deg. The 1.62 m model rotor was untrimmed with an essentially unrestricted tilt of the tip path plane. In combination with lag natural frequencies, collective pitch settings and flap lag coupling parameters, the data base comprises nearly 1200 test points (damping and frequency) in forward flight and 200 test points in hover. By computerized symbolic manipulation, a linear model was developed in substall to predict stability margins with mode identification. To help explain the correlation between theory and data it also predicted substall and stall regions of the rotor disk from equilibrium values. The correlation showed both the strengths and weaknesses of the theory in substall ((angle of attack) equal to or less than 12 deg)

A review of dynamic inflow and its effect on experimental correlations

A review is given of the relationship between experimental data and the development of modern dynamic-inflow theory. Some of the most interesting data, first presented 10 years ago at the Dynamic Specialist's Meeting, is now reviewed in light of the newer theories. These pure blade-flapping data correlate very well with analyses that include the new dynamic inflow theory, thus verifying the theory. Experimental data are also presented for damping with coupled inplane and body motions. Although inclusion of dynamic inflow is often required to correlate this coupled data, the data cannot be used to verify any particular dynamic inflow theory due to the uncertainties in modeling the inplane degree of freedom. For verification, pure flapping is required. However, the coupled data do show that inflow is often important in such computations

Computational aspects of helicopter trim analysis and damping levels from Floquet theory

Helicopter trim settings of periodic initial state and control inputs are investigated for convergence of Newton iteration in computing the settings sequentially and in parallel. The trim analysis uses a shooting method and a weak version of two temporal finite element methods with displacement formulation and with mixed formulation of displacements and momenta. These three methods broadly represent two main approaches of trim analysis: adaptation of initial-value and finite element boundary-value codes to periodic boundary conditions, particularly for unstable and marginally stable systems. In each method, both the sequential and in-parallel schemes are used and the resulting nonlinear algebraic equations are solved by damped Newton iteration with an optimally selected damping parameter. The impact of damped Newton iteration, including earlier-observed divergence problems in trim analysis, is demonstrated by the maximum condition number of the Jacobian matrices of the iterative scheme and by virtual elimination of divergence. The advantages of the in-parallel scheme over the conventional sequential scheme are also demonstrated

Assessment of ethanol production by pentose-degrading yeasts in an integrated corn-soy bio-refinery and testing of efficacy of chemical preservatives in distillers wet grains

This thesis can be divided into two parts: one was to evaluate the effect of integrating coproducts of enzyme assisted aqueous extraction of oil from soybean oilseeds, namely soy skim and soy insoluble fiber, in corn fermentation when different yeast species are used, and the second was to evaluate the efficacy of different chemical preservatives in increasing the shelf life of distillers wet grains (DWG), which is a co-product of the corn fermentation process and sold as animal feed. For evaluating the performance of different yeast species in ethanol production in an integrated corn-soy fermentation system, a review of published literature was conducted to understand the enzyme-assisted extraction process (EAEP) of oil from soybean. The review paper discusses in detail the evolution of enzymes based extraction process from aqueous extraction process and compares the process with conventional solvent-based oil extraction. The review indicates that the total time of oil extraction decreased and the oil yield from soybean oilseeds increased by 43-45% when enzymes were added to hexane-based oil extraction process. In aqueous extraction process, where water is used as extraction medium, the oil yield increased from 50% to around 85% when the soybean seeds were crushed using milling, flaking or extrusion. Hydrolytic enzymes were added to breakdown down cellulose and the protein network that captures oil molecules, which increased the oil yield to 98%. Pre-extraction steps such as flaking and extrusion, and enzymes used for extraction and de-emulsification (proteases and cellulases) are important factors that affect the oil and protein yield of EAEP of soybeans. Once the process and factors related to EAEP was understood, co-fermentation of corn and soy products was carried out while testing the fermentation performance of two yeasts species (Pichia stipitis and Candida shehatae) and comparing it with Saccharomyces cerevisiae. Since S. cerevisiae cannot assimilate pentose sugars such as xylose into ethanol, P. stipitis and C. shehatae were added to the system. Baseline data were obtained in synthetic media with 100% glucose, 100% xylose and glucose-xylose mixture. Further, fermentation was carried out for 72 hours in slurry containing just ground corn and water and slurry with ground corn, liquid soy skim and soy insoluble fiber. The performance of the three yeast species was compared on the basis of ethanol yield, ethanol production rate, ethanol final concentration and by-product concentration. It was observed that there was no significant difference at p\u3c0.05 between the ethanol yields of the yeasts species and their mixture in corn only slurry, the mixture of S. cerevisiae and C. shehatae had the highest ethanol yield when compared to others in corn-soy product slurry. Individually, the production rate of P. stipitis and C. shehatae was slightly lower but when inoculated along with S. cerevisiae, the maximum production rate was comparable to S. cerevisiae. Distillers wet grains is a co-product of ethanol production process from corn fermentation. These are unfermented ground corn; rich in fat, protein and few minerals. Addition of DWG to animal feed at 8-10% inclusion rate increased the total feeding value from 100 to 178 according to Klopfenstein et al (2008). Distillers grains are either fed as a wet product or dried to 20-30% moisture content. While the shelf life of dry product is higher and it is easy to transport, wet product is cheaper since no drying cost is involved. Wet product is preferred by livestock producers with farm near an ethanol plant. Since the moisture content is as high as 60%, chemical preservatives are used to increase the shelf life. The aim of the third objective was to test the efficacy of four commercial chemical preservatives and to compare their performance with a new preservative under development. Lactic acid bacteria, yeast and mold and aerobic heterotrophic cells were enumerated on the day of addition of preservatives up to day 10. Mold-X and Fungiless were very effective in controlling the population of yeasts and mold over the period of ten days. The performance of the new product, SHIELD, increased with increasing concentration and it was observed that the preservative was the most effective in decreasing the population of aerobic heterotrophs

Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations, Phase 2

A comparison with NASA conducted simulator studies has shown that the approximate digital method for computing rotor blade flapping responses to random inputs, tentatively suggested in Phase I Report, gives with increasing rotor advance ratio the wrong trend. Consequently, three alternative methods of solution have been considered and are described: (1) an approximate method based on the functional relation between input and output double frequency spectra, (2) a numerical method based on the system responses to deterministic inputs and (3) a perturbation approach. Among these the perturbation method requires the least amount of computation and has been developed in two forms - the first form to obtain the response correlation function and the second for the time averaged spectra of flapping oscillations

An experimental and analytical investigation of isolated rotor flap-lag stability in forward flight

For flap-lag stability of isolated rotors, experimental and analytical investigations are conducted in hover and forward flight on the adequacy of a linear quasisteady aerodynamics theory with dynamic inflow. Forward flight effects on lag regressing mode are emphasized. A soft inplane hingeless rotor with three blades is tested at advance ratios as high as 0.55 and at shaft angles as high as 20 degrees. In combination with lag natural frequencies, collective pitch settings and flap-lag coupling parameters, the data base comprises nearly 1200 test points (damping and frequency) in forward flight and 200 test points in hover. By computerized symbolic manipulations, an analytic model is developed in substall to predict stability margins with mode identification. It also predicts substall and stall regions to help explain the correlation between theory and data

Diversity, Distribution and Evolution of the Planktonic Diatom Family Chaetocerotaceae

The number and abundance of diatom species in environmental samples are counted traditionally by means of light microscopy (LM). However, recognizing –let alone, counting- species is often challenging because of the existence of cryptic species and intraspecific phenotypic plasticity. Proper characterization requires isolation of cells, growing them into monoclonal cultures, and characterizing the cultures genetically and morphologically. However, not all species grow in culture, featureless ones are less likely to be isolated, and the procedure is laborious. High-throughput sequencing (HTS) metabarcoding bypasses morphology; DNA is collected from environmental samples, a particular marker sequenced, and the resulting sequences sorted into clusters or terminal clades assumed to represent species. Yet, reference barcodes of taxonomically validated species are needed to identify these clades. This exercise is the main aim of my thesis. Since it is impossible to do this for all the diversity within a PhD thesis project, we selected Chaetocerotaceae, an abundant and diverse family of marine planktonic diatoms, containing two genera: Chaetoceros and Bacteriastrum. Its members uniquely share setae; thin siliceous tubes emerging from the valve corners, facilitating detection in samples. Strains were obtained from the Gulf of Naples (GoN), from Central Chile and Roscoff – at sites for which LTER time series data are available. A total of 270 strains were obtained from these sites, and their 18S- and partial 28S rDNA sequences and morphological information gathered. The strains grouped into 60 genetically distinct species, thus providing a dataset of validated Chaetocerotacean 18S reference barcodes. Inferred molecular phylogenies showed monophyletic Chaetocerotaceae as well as monophyletic Bacteriastrum inside paraphyletic Chaetoceros, and the presence of cryptic diversity. To start with taxonomic updates, the species C. sporotruncatus and C. dichatoensis were described within the C. socialis species-complex based on spore morphology and sequence differences. Several rDNA sequences contained spliceosomal introns (ca. 100bp) and/or group-I introns (ca. 400bp). Phylogenies inferred from the introns did not corroborate rDNA phylogenies, suggesting horizontal gene transfer. Presence/absence of introns in conspecific strains sampled in different seasons suggests population differentiation between these seasons. A HTS dataset consisting of V4-sequences (part of 18S) from 48 seawater samples taken over the seasons in the GoN revealed 76 terminal clades of which 46 grouped with a reference barcode. Some of these species occur year-round whereas most others are seasonal. Surprisingly, of the 30 clades belonging to unknown Chaetocerotacean species, two appear to be among the most abundant in the GoN

A detail review of types of Kshara with special emphasis on Rasashastra

Kshara (Alkali) has been in existence from ancient times. Their importance lies in the fact that they can be comfortably utilized to replace certain surgical procedures. Its properties are compared with that of Agni (fire) and yet it has its own special features too. Like although it is Ushna (hot) it is Sheeta (cool) in touch, although it has cutting and corroding property it can be utilized to be consumed orally as a medicine. And this is what makes it special. It is derived from plant, animal as well mineral sources. Its potency can be changed by combining various Kshara as per the need and requirement of the patient. Many Kshara’s have been described in our texts. This article aims at compiling those Kshara and elaborating their properties. There are also few Kshara which have not been classified as Kshara but which possess all the properties of Kshara, such Dravya have also been described in the current article. It is a review of Kshara and their properties as described in various Ayurvedic texts with special emphasis on Rasashastra (Iatrochemistry of Ayurveda) texts