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Conference paper titled, Comparing microclimate weather conditions from the weather research and forecasting (WRF) model with typical meteorological year (TMY) data for building energy simulations accepted for Building Simulation 2025 Conference in Brisbane, Australia in Aug 2025.
Abstract. Hillslope similarity is an active topic in hydrology because of its importance in improving our understanding of hydrologic processes and enabling comparisons and paired studies. In this study, we propose a holistic bottom-up hillslope clustering based on a region's integrative hydrodynamic response quantified by the seasonal changes in groundwater levels ΔP. The main advantage of the ΔP clustering is its ability to capture recharge and discharge processes. We test the performance of the ΔP clustering by comparing it to seven other common hillslope clustering approaches. These include clustering approaches based on the aridity index, topographic wetness index, elevation, land cover, and machine-learning that jointly integrate multiple data. We assess the ability of these clustering approaches to identify and categorize hillslopes with similar static characteristics, hydroclimate, land surface processes, and subsurface dynamics in a mountainous watershed – the East River – located in the headwaters of the Upper Colorado River Basin. The ΔP clustering performs very well in identifying hillslopes with six out of the nine characteristics studied. The variability among clusters as quantified by the coefficient of variation (0.2) is less in the ΔP and the machine learning approaches than in the others (> 0.3 for TWI, elevation, and land cover). We further demonstrate the robustness of the ΔP clustering by testing its ability to predict hillslope responses to wet and dry hydrologic conditions, of which it performs well when based on average conditions.
An integrated engine-generator for aircraft secondary power generation is described. The concept consists of an electric generator located inside a turbojet or turbofan engine and both concentric with and driven by one of the main engine shafts. The electric power conversion equipment and generator controls are located in the aircraft. When properly rated, the generator serves as an engine starter as well as a source of electric power. This configuration reduces or eliminates the need for an external gear box on the engine and permits reduction in the nacelle diameter.
The integrated engine-generator concept consists of an electric generator located inside a turbojet or turbofan engine and both concentric with and driven by one of the main engine shafts. The electric power-conversion equipment and generator controls are conveniently located in the aircraft. When properly rated, the generator serves as an engine starter as well as a source of electric power. The available generating capacity permits use of electrically driven engine accessories. This reduces or eliminates the need for an external gearbox on the engine, thereby simplifying the engine and nacelle assembly and increasing aircraft design flexibility. The nacelle diameter can then be decreased, resulting in less aerodynamic drag and reduced takeoff gross weight.
Experimental aerodynamic investigations were conducted on an 0.0405 scale representation of the -89B (2A) Space Shuttle Orbiter in a 7.75 x 11.00 ft low speed wind tunnel during the time period from July 27, 1973 to August 3, 1973. The primary test objective was to investigate the aerodynamic effects of engine nacelle grouping and location on the orbiter ferry mission configuration. Five nacelles were tested, both individually mounted as well as mounted in a podded configuration, at the baseline position and moved 45.0 in. aft (full scale). Orbiter control effectiveness, both with and without nacelles, was recorded at elevon deflections of 0 deg, 5 deg, 10 deg, -10 deg and -20 deg and aileron deflections, about 0 deg elevon, of 0 deg, 5 deg, 10 deg, and 15 deg. The model was sting mounted on a 2.5 inch diameter internal strain gage balance entering through the base region. The nominal angle of attack range was -4 deg or = alpha or = 30 deg. Yaw polars were recorded over the beta range of -10 deg or = beta or = at fixed angles of attack of 0 deg and 10 deg.
The airglow studies were initiated in July 1961 in response to the discovery of unusual phenomena in the tropical airglow as observed from Algeria. Hawaii, being the southern-most area in the United States and within the tropics, and possessing high mountains with frequent clear skies well isolated from the contaminating light and dust of civilization, appeared to be an ideal location for establishing a tropical airglow station. The University of Hawaii was already developing the Mees Solar Laboratory on Haleakala on the island of Maui, so that the addition of a night sky observatory was a natural development. The collection of data covers a span of about seven and one-half years, including the minimum of the solar cycle in 1963 and just getting into the next maximum in 1968-69. It was unfortunate that financial limitations did not permit the continuation of the observations through one complete solar cycle.
The author has identified the following significant results. From the data that have been analyzed thus far, it is apparent that certain parameters of the vegetation (green biomass and vegetation moisture content) are well correlated with ERTS data at some sites, yet the relationship is poor at other locations. The analyses indicate that the green wave development (spring) can be readily detected in the Great Plains Corridor. Consequently, ERTS-1 data provide a new tool for monitoring range readiness on a regional basis. The onset of summer drought and its duration can also be monitored. Data from ten G.P.C. sites suggest that the satellite coverage has been adequate to monitor the status of rangeland vegetation for regional management purposes.
HEAO 3 Cosmic Gamma-Ray Spectrometer evidence is presented for the existence of a time-varying, unshifted, narrow 511 keV line emission from the vicinity of the galactic center. Although uncertainties exist regarding the spatial extent of the features as well as its centroid, all data are consistent with emission from a single point source located at the galactic center. This interpretation would require a source luminosity of 2 x 10 to the 37th ergs/sec, and a positron annihilation rate of about 10 to the 43rd/sec. It is concluded that a variable source of positrons which could generate such an annihilation figure might be a massive black hole at the galactic center, as has been suggested by IR observations.
Venus deflects incident solar wind by means of thermal and magnetic pressure, both of which are produced by ionospheric currents that are in turn driven by pressure gradients and electric fields induced in the ionosphere by the flowing magnetized solar wind plasma. The ionospheric currents connect across the ionopause into the ionosheath region, and close on, and behind, the bow shock. The computed ionospheric plasma velocity distribution is found to be spatially asymmetric, with the fastest flow velocities lying perpendicular to the ionospheric magnetic fields. Computations also indicate that the ionosphere is susceptible to an MHD shear instability whose extent and location is a function of external solar wind conditions. The present Venus ionosphere model compares well with in situ Pioneer Venus Orbiter observations.
The model and the computer program developed provides the velocity, location, and circulation of the tip vortices of a two-blade helicopter in and out of the ground effect. Comparison of the theoretical results with some experimental measurements for the location of the wake indicate that there is excellent accuracy in the vicinity of the rotor and fair amount of accuracy far from it. Having the location of the wake at all times enables us to compute the history of the velocity and the location of any point in the flow. The main goal of out study, induced velocity at the rotor, can also be calculated in addition to stream lines and streak lines. Since the wake location close to the rotor is known more accurately than at other places, the calculated induced velocity over the disc should be a good estimate of the real induced velocity, with the exception of the blade location, because each blade was replaced only by a vortex line. Because no experimental measurements of the wake close to the ground were available to us, quantitative evaluation of the theoretical wake was not possible. But qualitatively we have been able to show excellent agreement. Comparison of flow visualization with out results has indicated the location of the ground vortex is estimated excellently. Also the flow field in hover is well represented.
The Jicamarca radar (Long. 76.52W, Lat. 11.56S), located at 20 km from Lima at approximately 500 meters over sea level, is surrounded by mountains which provide a good shield from man-made interference. The radio horizon goes from a few hundred meters, across the dry valley where it is located, to 15 km, along the valley in the direction of the continental divide. This limits the clutter to 15 km, except for one high peak at 21 km. It is the most equatorial of all existing MST radars. Its proximity to the Andes, makes its location unique for the study of lee waves and orographic-induced turbulence. Vertical as well as horizontal projections of MST velocities are obtained by simultaneously pointing with different sections of the antenna into three or four different directions. The transmitters, receivers, and systems for data acquisition, processing, and control are included.
Seams tracked for automatic control of welding. Optoelectronic system based on relatively simple array of optical proximity sensors locates edge of plate. Used to control automatic production machinery. System follows curved seams as well as straight ones, and neither special control programming nor precise initial positioning workpiece necessary for accurate tracking of seam.
A modified independent modal space control (MIMSC) method is developed for designing active vibration control systems for large flexible structures. The method accounts for the interaction between the controlled and residual modes. It incorporates also optimal placement procedures for selecting the optimal locations of the actuators in the structure in order to minimize the structural vibrations as well as the actuation energy. The MIMSC method relies on an important feature which is based on time sharing of a small number of actuators, in the modal space, to control effectively a large number of modes. Numerical examples are presented to illustrate the application of the method to generic flexible systems. The results obtained suggest the potential of the devised method in designing efficient active control systems for large flexible structures.
A modified independent modal space control (MIMSC) method is developed for designing active vibration control systems for large flexible structures. The method accounts for the interaction between the controlled and residual modes. It incorporates also optimal placement procedures for selecting the optimal locations of the actuators in the structure in order to minimize the structural vibrations as well as the actuation energy. The MIMSC method relies on an important feature which is based on time sharing of a small number of actuators, in the modal space, to control effectively a large number of modes. Numerical examples are presented to illustrate the application of the method to generic flexible systems. The results obtained suggest the potential of the devised method in designing efficient active control systems for large flexible structures.
A modified independent modal space control (MIMSC) method is developed for designing active vibration control systems for large flexible structures. The method accounts for the interaction between the controlled and residual modes. It incorporates also optimal placement procedures for selecting the optimal locations of the actuators in the structure in order to minimize the structural vibrations as well as the actuation energy. The MIMSC method relies on an important feature which is based on time sharing of a small number of actuators, in the modal space, to control effectively a large number of modes. Numerical examples are presented to illustrate the application of the method to generic flexible systems. The results obtained suggest the potential of the devised method in designing efficient active control systems for large flexible structures.
High resolution observations of molecules in external galaxies are essential to understanding physical processes leading to the formation of stars. One question is whether there is a spiral structure in the molecular gas, but it was not possible to resolve the spiral arms of external galaxies until the advent of large millimeter-wave telescopes. With the Institute for Radio Astronomy in the Millimeter Range (IRAM) 30 m telescope, researchers are carrying through the mapping of NGC 6946 in the CO-12(1-0) and (2-1) lines. This galaxy is a large, gas-rich Scd spiral with a strong star formation activity. NGC 6946 is well studied at radio and optical wavelengths, so that it is possible to compare the location of the spiral arms tracers: HI ridge, HII regions and molecular clouds. The disk CO emission is very contrasted (no lines for some positions, 1 K in CO(1-0) for some others) and correlated with the optical spiral arms: this clearly shows up in a figure which presents superimposed contours of CO(2-1) integrated emissivity and of H alpha line emission. The agreement is very good, and there is no displacement across the arm between the CO, HI and H alpha ridges of emission. The arms are barely resolved by the 23 inch beam and the molecular contrast averaged over the map is about 4. The CO(2-1) maxima are closer to the position of the HII regions than those of CO(1-0), which could be due to variations of excitation conditions. The CO excitation in the disk of NGC 6946 is low: when all data are convolved to the same resolution of 23 inches the CO(2-1) lines are about 0.45 times fainter than the CO(1-0) ones, while in the nucleus they have roughly the same intensity. This suggests that in the disk of NGC 6946 most of the CO emission comes from cold optically thick gas located in cloud envelopes rather than from cloud cores. The molecular and atomic component in the observed regions of NGC 6946 seems to be organized in large gaseous complexes.
This paper addresses the application of ultrasonic sensing to damage assessment in ceramics and ceramic matrix composites. It focuses on damage caused by thermal shock or oxidation at elevated temperatures, which often results in elastic anisotropy. This damaged-induced anisotropy is determined by measuring the velocities of ultrasonic waves in different propagation directions. Thermal shock damage is assessed in ceramic samples of reaction bonded silicon nitride (RBSN). Thermal shock treatment from different temperatures up to 1000 C is applied to produce the microcracks. Results indicate that most microcracks produced by thermal shock are located near sample surfaces. Ultrasonic measurements using the surface wave method are found to correlate well with measurements of degradation of mechanical properties obtained independently by other authors using destructive methods. Oxidation damage is assessed in silicon carbide fiber/reaction bonded silicon nitride matrix (SCS-6/RBSN) composites. The oxidation is done by exposing the samples in a flowing oxygen environment at elevated temperatures, up to 1400 C, for 100 hr. The Youngs' modulus in the fiber direction as obtained from ultrasonic measurements decreases significantly at 600 C but retains its original value at temperatures above 1200 C. This agrees well with the results of destructive tests by other authors. On the other hand, the transverse moduli obtained from ultrasonic measurements decrease continually until 1200 C. Measurements on the shear stiffnesses show behavior similar to the transverse moduli. The results of this work show that the damage-induced anisotropy in both ceramics and ceramic matrix composites can be determined successfully by ultrasonic methods. This suggests the possibility of assessing damage severity using ultrasonic techniques.
This document contains a comprehensive bibliography of the published works, and a short biography, of Dr. Chul Park. The contents of this bibliography were compiled primarily from the NASA RECON data base. The RECON citations have been modified to appear in a uniform format with all other listed citations . These other citations were located by computer searches in the INSPEC, NTIS, COMPENDEX, and Chemical Abstracts data bases, as well as through the cooperation of Dr. Chul Park, and his associates in the Reacting Flow Environments Branch at NASA Ames Research Center. All citations are presented in an approximate reverse chronological order from the present date. This work was created to honor the occasion of Dr. Chul Park's retirement on December 14, 1994, after 27 years of distinguished government service at the NASA Ames Research Center.