Properties of nonaqueous electrolytes Sixth summary report, 20 Sep. 1967 - 19 Mar. 1968
Physical properties and structural studies on propylene carbonate, dimethyl formamide, and acetonitrile solvent electrolytes
Foster, J. N.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Properties of nonaqueous electrolytes
Nuclear magnetic resonance and electron paramagnetic resonance techniques for aprotic electrolytes
Foster, J. N.↗
Practical phase reference detectors for fully modulated PSK signals.
Optimum receiver structure for estimating PSK information signal phase derived together with matched filter detector performance
Hon, W.↗
Properties of nonaqueous electrolytes
Physical property measurements and structural studies conducted in aprotic solvents using various solutes are applicable to the further development of lithum batteries. Structural studies utilize nuclear magnetic resonance and electron paramagnetic resonance techniques.
Foster, J. N.↗
Investigation of electrolyte systems for lithium batteries Final report, 26 May 1969 - 25 Jul. 1970
Nuclear magnetic resonance, solubility, stability, and resistance of electrolytes for lithium batteries
Hon, J. F.↗
Thickness of mare material in the Tranquillitatis and Nectaris basins
The present work reports on the construction of an isopach map of basin-filling materials based on data obtained from buried craters and partially buried craters in the Tranquillitatis and Nectaris basins. The data suggest that materials filling irregular maria are thin. Improved relief measurements based on Apollo metric photography are required for more accurate topographic mapping.
De Hon, R. A.↗
Preliminary Candidate Advanced Avionics System (PCAAS)
Specifications which define the system functional requirements, the subsystem and interface needs, and other requirements such as maintainability, modularity, and reliability are summarized. A design definition of all required avionics functions and a system risk analysis are presented.
Teper, G. L.↗
Thickness of the western mare basalts
The basalts of the western maria occupy large circular basins and surrounding lowlands associated with the basins. Mare Imbrium and Mare Humorum are the only well-preserved circular basins. Isopach mapping suggests that the vast expanse of basalt plains of Oceanus Procellarum mantles a composite structure of several coalescing basins. The thickest basalts are found in Mare Imbrium, Mare Humorum, and in the western part of the Oceanus Procellarum. Relatively thin basalts are found south and southwest of Mare Imbrium, in the Central Lowland region, and in northern Procellarium. For the most part, the general conclusions of earilier studies of the eastern maria are confirmed in the western maria.
De Hon, R. A.↗
A thermochemical calculation of the pyroxene saturation surface in the system diopside-albite-anorthite
The pyroxene saturation surface in the system diopside-albite-anorthite may be calculated to + or - 10 C from thermochemical data over most of its composition range. The thermochemical data used are the experimentally determined enthalpies of mixing of the ternary liquids and the enthalpy of fusion of diopside. These are combined with a mixing model for the configurational entropy in the melt and the activity of CaMgSi2O6 in the clinopyroxene, which is less than unity due to departures from CaMgSi2O6 stoichiometry. The two-lattice melt model appears to work satisfactorily throughout the pyroxene primary phase field but probably needs modification at more anorthite-rich compositions.
Hon, R.↗
Variations in interior morphology of 15-20 km lunar craters - Implications for a major subsurface discontinuity
Craters vary in morphology as a function of crater diameter, age, and mode of origin. This study concentrates on the morphology of young lunar impact craters within a limited size range. Elimination of morphologic variations generally attributed to crater size or age leaves a small population which should nearly reflect the varying properties of the lunar substrate. The sample consists of 17 craters 15-20 km in diameter with both simple and complex morphologies. While depth/diameter ratios do not obviously differ between mare and highland subsets, apparent depth, rim height, and profile data do differ distinctly. Highland craters tend to be deep, simple, and bowl-shaped. Mare craters tend to be shallow and flat-floored. Rim heights of complex mare craters are typically greater than those of simple craters. Differences of highland and mare crater morphologies are attributed to variations in the thickness of the lunar megaregolith. Highland craters in this size range do not penetrate the megaregolith. The depth and morphology of complex craters are controlled by the discontinuity at the transition from highly brecciated megaregolith to more coherent crystalline material of the upper crust.
De Hon, R. A.↗
Selenographic distribution of apparent crater depth
If apparent crater depth is a function of crater diameter, then the frequencies of crater depth and diameter should be similar and the distribution of apparent depths of craters on the lunar surface should be random. Apparent depths of complex craters, which range from 0.2 to 4.3 km on the moon, exhibit little correlation with crater diameters. Crater frequency decreases at increasing diameters, but apparent crater depth displays a Gaussian distribution. The average crater depth for all young craters is 1.8 km. The mean depth of craters on the maria is 1.3 km, and the mean depth of craters on the highlands is 2.1 km. A contour map of apparent crater depths exhibits sufficient organization to suggest that the apparent crater depth is correlated to major lunar provinces. In general, regions of shallow craters are associated with basin interiors. Greater apparent depths are associated with highland terrains.
De Hon, R. A.↗
Martian volcanic materials - Preliminary thickness estimates in the eastern Tharsis region
Mars displays a variety of volcanic materials from high standing constructs to smooth plains. These materials are evaluated in terms of their susceptibility to thickness determination, and a representative area is analyzed. The Martian ridged plains are much like lunar maria in both surface expression and apparent mode of emplacement. Flooded craters within the ridged plains materials provide an estimate of the thickness distribution. In the Tharsis region, ridged plains materials occur as part of the layered sequence on the east flank of the Tharsis dome. Partially buried craters indicate that the ridged plains materials range from zero meters thick at their eastern limit to over 1.5 km thick westward on the flank of the dome where they are overlain by younger materials. These materials are responsible for only a small portion of the total relief of the Tharsis dome.
De Hon, R. A.↗
Frequency-shaped large-angle maneuvers
The paper considers the problem of maneuvering a flexible spacecraft through large angles in finite time. The basic control problem is divided into two parts. The first part consists of generating a frequency-shaped open-loop solution for the nonlinear rigid body as the nominal solution. The resulting two-point boundary-value problem is solved by introducing a continuation method for altering the mass distribution and boundary conditions for the spacecraft. For the second part, a feedback control is designed by linearizing the flexible body response about several points along the rigid body nominal solution. The perturbation gains are designed by using a frequency-shaped cost functional approach. The gains are linearly interpolated to produce smooth control time-histories as the linear piecewise constant plant models change during the maneuver.
Chun, Hon M.↗
Large-angle slewing maneuvers for flexible spacecraft
A new class of closed-form solutions for finite-time linear-quadratic optimal control problems is presented. The solutions involve Potter's solution for the differential matrix Riccati equation, which assumes the form of a steady-state plus transient term. Illustrative examples are presented which show that the new solutions are more computationally efficient than alternative solutions based on the state transition matrix. As an application of the closed-form solutions, the neighboring extremal path problem is presented for a spacecraft retargeting maneuver where a perturbed plant with off-nominal boundary conditions now follows a neighboring optimal trajectory. The perturbation feedback approach is further applied to three-dimensional slewing maneuvers of large flexible spacecraft. For this problem, the nominal solution is the optimal three-dimensional rigid body slew. The perturbation feedback then limits the deviations from this nominal solution due to the flexible body effects. The use of frequency shaping in both the nominal and perturbation feedback formulations reduces the excitation of high-frequency unmodeled modes. A modified Kalman filter is presented for estimating the plant states.
Chun, Hon M.↗
Direct solar-pumped iodine laser amplifier
A XeCl laser pumped iodine laser oscillator was developed which will be incorporated into the Master Oscillator Power Amplifier (MOPA) system. The developed XeCl laser produces output energy of about 60 mJ per pulse. The pulse duration was about 10 nsec. The kinetic model for the solar-pumped laser was refined and the algorithm for the calculation of a set of rate equations was improved to increase the accuracy and the efficiency of the calculation. The improved algorithm was applied to explain the existing experimental data taken from a flashlamp pumped iodine laser for three kinds of lasants, i-C3F7I, n-C4F9I, and t-C4F9I. Various solid laser materials were evaluated for solar-pumping. The materials studied were Nd:YAG, Nd:YLF, and Cr:Nd:GSGG crystals. The slope efficiency of 0.17 percent was measured for the Nd:YLF near the threshold pump intensity which was 211 solar constants (29W/sq cm). The threshold pump intensity of the Nd:YAG was measured to be 236 solar constants (32W/sq cm) and the near-threshold slope efficiency was 0.12 percent. True CW laser operation of Cr:Nd:GSGG was possible only at pump intensities less than or equal to 1,500 solar constants (203 W/sq cm). This fact was attributed to the high thermal focusing effect of the Cr:Nd:GSGG rod.
Han, Kwang S.↗
Evolution of hairpin vortices in a shear flow
Recent experimental studies suggest that the hairpin vortex plays an important (and perhaps dominant) role in the dynamics of turbulent flows near walls. In this study a numerical procedure is developed to allow the accurate computation of the trajectory of a 3-D vortex having a small core radius. For hairpin vortices which are convected in a shear flow above a wall, the calculated results show that a 2-D vortex containing a small 3-D disturbance distorts into a complex shape with subsidiary hairpin vortices forming outboard of the original hairpin vortex. As the vortex moves above the wall, it induces unsteady motion in the viscous flow near the wall: numerical solutions suggest that the boundary-layer flow near the wall will ultimately erupt in response to the motion of the hairpin vortex and in the process a secondary hairpin vortex will be created. The computer results agree with recent experimental investigations.
Hon, T.-L.↗
Test and validation for robot arm control dynamics simulation
The Flight Telerobotic Servicer (FTS) program will require an ability to develop, in a cost effective manner, many simulation models for design, analysis, performance evaluation, and crew training. Computational speed and the degree of modeling fidelity associated with each simulation must be commensurate with problem objectives. To demonstrate evolving state-of-the-art general purpose multibody modeling capabilities, to validate these by laboratory testing, and to expose their modeling shortcomings, two focus problems at the opposite ends of the simulation spectrum are defined: (1) Coarse Acquisition Control Dynamics. Create a real time man-in-the-control-loop simulator. Provide animated graphical display of robot arm dynamics and tactile feedback sufficient for cueing the operator. Interface simulator software with human operated tactile feedback controller; i.e., the Kraft mini-master. (2) Fine, Precision Mode Control Dynamics. Create a high speed, high fidelity simulation model for the design, analysis, and performance evaluation of autonomous 7 degree-of-freedom (DOF) trajectory control algorithms. This model must contain detail dynamic models for all significant dynamics elements within the robot arm, such as joint drive mechanisms.
Yae, K. Harold↗
Experimental validation of Order (n) DISCOS
An order (n) algorithm is developed for use in the industry-standard DISCOS (Dynamics Interaction Simulation of Controls and Structures) program for flexible multibody system dynamics simulation. This version should be more computationally efficient than conventional DISCOS for problems where a large number of bodies are involved. Program-dependent changes to DISCOS are described for reducing the number of bodies required to model gear reduction and nonlinear stiffness as internal effects. The gear reduction modification can be extended to general applications, such as gear box, rack and pinion, lever joint, and screw rotation models. Upgrading DISCOS for future use include the addition of robotics capabilities such as event-driven topology changes, surface sliding, pick-and-place, and multiarm hand-off.
Chun, Hon M.↗