Lambert's problem and cross-product steering Quarterly report

Formulas for solving Lambert problem in case of single orbit

Optimal Estimation of Several Linear Parameters in the Presence of Lorentzian Thermal Noise

In a previous article we developed an approach to the optimal (minimum variance, unbiased) statistical estimation technique for the equilibrium displacement of a damped, harmonic oscillator in the presence of thermal noise. Here, we expand that work to include the optimal estimation of several linear parameters from a continuous time series. We show that working in the basis of the thermal driving force both simplifies the calculations and provides additional insight to why various approximate (not optimal) estimation techniques perform as they do. To illustrate this point, we compare the variance in the optimal estimator that we derive for thermal noise with those of two approximate methods which, like the optimal estimator, suppress the contribution to the variance that would come from the irrelevant, resonant motion of the oscillator. We discuss how these methods fare when the dominant noise process is either white displacement noise or noise with power spectral density that is inversely proportional to the frequency ($1/f$ noise). We also construct, in the basis of the driving force, an estimator that performs well for a mixture of white noise and thermal noise. To find the optimal multi-parameter estimators for thermal noise, we derive and illustrate a generalization of traditional matrix methods for parameter estimation that can accommodate continuous data. We discuss how this approach may help refine the design of experiments as they allow an exact, quantitative comparison of the precision of estimated parameters under various data acquisition and data analysis strategies.Comment: 16 pages, 10 figures. Accepted for publication in Classical and Quantum Gravit

Floristic Inventory of Woollen’s Gardens Nature Preserve, Indianapolis, Marion County, Indiana, USA, With Quantitative Vegetation Sampling of Permanent Plots in 2003 and 2016

Urban forest fragments face challenges to habitat quality due to small size, isolation from larger natural areas, and close association with anthropogenic disturbance. Monitoring changes in vegetation can inform management practices targeted at preserving biodiversity in the face of these threats. Woollen’s Gardens is a high-quality mesic upland forest preserve in the city of Indianapolis, Indiana, USA, with a beechmaple older-growth forest and a significant display of showy spring wildflowers. The entire preserve was inventoried and quantitative vegetation analysis along seven 100 m transects was conducted in 2003 and again in 2016 to track changes. Data from both years document a high-quality flora with few non-native plants. Floristic Quality Index values for native species, derived from Floristic Quality Assessment, were 50.2 in 2003 and 47.3 in 2016. Native mean C-values of 4.5 and 4.3 for each year support that the site is comparable to the highest quality natural areas in central Indiana. Values declined little when non-natives were included, indicating non-natives are having little negative impact on the flora. Although non-natives comprised less than 10% of the flora, 11 of the 16 species are considered invasive in Indiana. In 2003, invasive Amur honeysuckle (Lonicera maackii) was among species in plots with the highest relative importance value. In 2016, invasive wintercreeper (Euonymus fortunei) was among these species. Limited public access to Woollen’s Gardens minimizes human disturbance, but invasive species are a threat to vegetation quality. Continuation of eradication efforts is strongly recommended before populations of these non-natives become more difficult to control

A force balance system for the measurement of skin friction drag force in the presence of large vibrations and temperatures

Design of counterbalance system for skin friction drag measurements on hypersonic vehicle

Living \u3cem\u3eMore Than\u3c/em\u3e Just Enough for the City: Persistence of High-Quality Vegetation in Natural Areas in an Urban Setting

Urban environments pose special challenges to flora, including altered disturbance regimes, habitat fragmentation, and increased opportunity for invasion by non-native species. In addition, urban natural area represents most people’s contact with nature, given the majority of the world’s population currently live in cities. We used coefficients of conservatism (C-values), a system that ranks species based on perceived fidelity to remnant native plant communities that retain ecological integrity, to quantify habitat quality of 14 sites covering 850 ha within the city of Indianapolis, Indiana, in the Midwestern United States. All sites contained significant natural area and were inventoried via intensive complete censuses throughout one or two growing seasons within the last 15 years. Mean C-values for five sites were high, especially when compared to values reported for the highest quality preserves in central Indiana. However, for most sites the difference in mean C-value with and without non-natives was rather high, meaning that natural quality is likely to have been compromised by the presence of non-natives. Sites receiving the highest levels of stewardship and those with the least public access via trails had the highest mean native C-values. A total of 34 invasive non-native species were found across all 14 sites. Most were woody species. Mean C-value over all sites was significantly negatively correlated with the number of non-natives present, especially those considered invasive. These results demonstrate for the Indianapolis area, and likely other urbanized Midwestern cities, remnant natural areas can retain high ecological value, especially if they receive regular environmental stewardship

Vibration limiting of rotors by feedback control

Experimental findings of a three mass rotor with four channels of feedback control are reported. The channels are independently controllable with force being proportional to the velocity and/or instantaneous displacement from equilibrium of the shaft at the noncontacting probe locations (arranged in the vertical and horizontal attitudes near the support bearings). The findings suggest that automatic feedback control of rotors is feasible for limiting certain vibration levels. Control of one end of a rotor does afford some predictable vibration limiting of the rotor at the other end

Investigation of Systems and Techniques for Multicomponent Microforce Measurements on Wind Tunnel Models Semiannual Status Report, 15 Jul. 1965 - 15 Jan. 1966

Skin friction drag sensor and multicomponent microforce wind tunnel balance syste

THE PROFITABILITY OF AGRICULTURAL CUSTOMERS FOR COMMERCIAL BANKS IN THE SOUTHEAST

Agricultural Finance,