NASA Lidar system support and MOPA technology demonstration

A series of lidar design and technology demonstration tasks in support of a CO2 lidar program is discussed. The first of these tasks is discussed in Section VI of this report under the heading of NASA Optical Lidar Design and it consists of detailed recommendations for the layout of a CO2 Doppler lidar incorporating then existing NASA optical components and mounts. The second phase of this work consisted of the design, development, and delivery to NASA of a novel acousto-optic laser frequency stabilization system for use with the existing NASA ring laser transmitter. The second major task in this program encompasses the design and experimental demonstration of a master oscillator-power amplifier (MOPA) laser transmitter utilizing a commercially available laser as the amplifier. The MOPA design including the low chirp master oscillator is discussed in detail. Experimental results are given for one, two and three pass amplification. The report includes operating procedures for the MOPA system

A high-throughput approach developing lithium-niobium-tantalum oxides as electrolyte/cathode interlayers for high-voltage all-solid-state lithium batteries

The ever-increasing interest in sustainable mobility is driving the development of innovative batteries with increased energy densities relative to currently commercialized lithium-ion batteries. All-solid-state batteries using 5 V-class positive electrodes are one of those batteries due to their larger volumetric energy density and their superior durability. However, their power density tends to be limited by the large charge transfer resistance at their electrolyte/5 V-electrode interfaces; one explanation for this is the development of significant Li+ deficient layers at the interface. Here we propose a new interlayer material that would effectively resolve the Li+ deficient layers. The partially-crystallized Li56Nb22Ta22 oxide was identified using the molecular beam epitaxy (MBE) based high-throughput physical vapor deposition (HT-PVD) approach. Its higher ionic conductivity of 4.2 ?S cm?1 and higher permittivity of 165 when measured at 254 kHz, relative to those of conventional LiNbO3 interlayer (1.8 ?S cm?1 and 95, respectively) will be effective for fast charge transfer reactions at the electrolyte /cathode interfaces in 5 V-class all-solid-state batteries

To Perfect the Peace Establishment: Congressional Attempts to Find the Proper Size for the Regular Army, 1821-1855

This study is an attempt to understand better how the Congress of the United States worked to establish the proper size and form of the Peace Establishment of the United States between 1821 and 1855. Central to this study is an attempt to determine if partisan or sectional attitudes were key factors in how Congress viewed the Regular Army. The research in this study is centered on the primary materials generated by the Congresses under study. The debates and speeches conducted in Congress as found in the contemporary reports of the day, the Journals of the House and Senate, and the reports and documents produced by the two Houses during the period are key sources Roll call votes are analyzed when available in an attempt to determine if there were any party or sectional differences in the voting patterns. Since only a few roll calls were taken and recorded on the issue, each vote is treated separately. In an attempt to clarify the sectional issue, a three region model is used. A state is placed in its traditional North or South region unless it bordered a frontier area. States bordering a territory are placed in the Frontier region. Districts which have differing characteristics than their parent states have been moved into the region with which they share the most in common. The conclusions of the research show that party and section played no significant role in the debates to find the proper size of the Peace Establishment between 1821 and 1855. With only the most minor exceptions, no party or section disagreed with the decisions of the Congress on the eight individual issues studied. At most, one party or section supported the change to a greater or lesser degree than the rest of the Congress. The general trend to increase of the Regular Army between 1821 and 1855 occurred in response to the great increase in the size of the country and the need to have a military presence far beyond the settled frontier

A Comparison of Transient Heat-Pump Cycle Simulations with Homogeneous and Heterogeneous Flow Models

This paper compares the effects of two different refrigerant flow modeling assumptions on the transient performance of vapor-compression heat pump cycles. These simulations are developed in the next-generation modeling language Modelica, which uses an acausal, equation-oriented approach to describe physical systems. The effect of the flow assumptions and specific slip ratio correlations on both the equilibrium operating point and the transient behavior of the cycle are demonstrated through these simulations. It is shown that equivalent simulations with different slip ratio correlations each have different equilibrium mass inventories, and that some aspects of the transient system behavior exhibits minor differences between the representative simulations. The effect of the software implementation on the model performance is also discussed

Modeling and Analysis of Pressure Drop Oscillations in Horizontal Boiling Flow

In general, two-phase flow phenomena can be described based on the one-dimensional conservation laws. Models with different formulations can be obtained with different assumptions. This paper presents three models with different complexity to simulate pressure drop oscillations. The direct comparison indicates that there are substantial differences between these models. The mechanism of pressure drop oscillations is discussed and the effect of operating parameters on system instability is explored. It is shown that two bifurcation points can exist when varying heat input and inlet subcooling. Root locus analysis corroborates the simulation results

Numerical Modeling of Fin-and-Tube Condenser with Wet-wall Desuperheating

Current heat exchanger simulation models typically divide the condenser into three regimes (desuperheating, two-phase and subcooled) and assume that condensation does not start until the bulk refrigerant flow reaches a state of saturated vapor. However, plenty of experiments have verified that condensation can occur much earlier than that when the tube wall surface temperature drops below the dew point of refrigerant even though the bulk flow is still superheated. This phenomenon is called wet-wall desuperheating (also referred to as wet-desuperheating, or condensation from desuperheated vapor in some publications). Wet-wall desuperheating is rarely modelled in the extant heat exchanger simulations due to lack of understanding in its physical process. However, neglecting this important phenomenon may lead to substantial performance prediction errors. This paper proposes a new fin-and-tube condenser heat exchanger model to bridge the research gap. In the proposed model, the heat exchanger is divided into four regimes: dry-wall desuperheating, wet-wall desuperheating, two-phase condensation and subcooled. The existence of dry-wall desuperheating and the onset point of wet-wall desuperheating are determined by rigorous algorithms. Boundaries between different flow regimes are captured to eliminate numerical discontinuities. A tube-by-tube analysis is adopted to allow for the simulation of complex tube circuitries. Simulation studies are performed to demonstrate the capabilities of the proposed model. The results show that wet-wall desuperheating always exists in the condenser with refrigerant vapor entering at the inlet, and neglecting the phenomenon can lead to significant under prediction for heat exchanger performance

Peripheral Electrical and Magnetic Stimulation to Augment Resistance Training

Electrical stimulation (ES) and magnetic stimulation (MS), applied peripherally, may be used to elicit muscle contractions to increase muscle hypertrophy, increase muscle strength and reduce knee laxity in rehabilitation following injury. We aimed to examine the effect of a three-week exercise programme designed to induce muscle hypertrophy augmented by peripheral ES and MS. We hypothesised that the use of peripheral stimulation to augment voluntary drive during a resistance-training protocol would induce more repetitions thus leading to increased thigh circumference, muscle layer thickness, and quadriceps strength whilst decreasing knee laxity. Thirty healthy participants were divided randomly into either ES, MS or Control groups. Five resistance training sessions were carried out, consisting of four sets of quadriceps extensions. During the first three sets the participants performed eight repetitions at 85% of their 1-repetition maximum (1-RM). On the last set, the participants were instructed to perform the exercise until failure. The augmentation of peripheral stimuli allowed the MS and ES groups to continue to exercise producing, on average, 4 ± 2 and 7 ± 6 additional repetitions with ES and MS, respectively. Following the training, significant increases were observed for both 1-RM (p = 0.005) and muscle layer thickness (p = 0.031) whilst no change was observed in thigh circumference (p = 0.365). Knee laxity decreased (p = 0.005). However, there were no significant differences in the stimulation groups compared with control for any of these measurements. The additional repetitions elicited by stimulation after the point of failure suggests that peripheral electrical and/or magnetic stimulation may be useful as an adjunct for resistance training. However, this effect of resistance training augmented by peripheral stimulation on hypertrophy, strength and knee laxity may be small