Solid state lasers for use in non-contact temperature measurements

The last decade has seen a series of dramatic developments in solid state laser technology. Prominent among these has been the emergence of high power semiconductor laser diode arrays and a deepening understanding of the dynamics of solid state lasers. Taken in tandem these two developments enable the design of laser diode pumped solid state lasers. Pumping solid state lasers with semiconductor diodes relieves the need for cumbersome and inefficient flashlamps and results in an efficient and stable laser with the compactness and reliability. It provides a laser source that can be reliably used in space. These new coherent sources are incorporated into the non-contact measurement of temperature. The primary focus is the development and characterization of new optical materials for use in active remote sensors of the atmosphere. In the course of this effort several new materials and new concepts were studied which can be used for other sensor applications. The general approach to the problem of new non-contact temperature measurements has had two components. The first component centers on passive sensors using optical fibers; an optical fiber temperature sensor for the drop tube was designed and tested at the Marshall Space Flight Center. Work on this problem has given insight into the use of optical fibers, especially new IR fibers, in thermal metrology. The second component of the effort is to utilize the experience gained in the study of passive sensors to examine new active sensor concepts. By active sensor are defined as a sensing device or mechanism which is interrogated in some way be radiation, usually from a laser. The status of solid state lasers as sources for active non-contact temperature sensors are summarized. Some specific electro-optic techniques are described which are applicable to the sensor problems at hand. Work on some of these ideas is in progress while other concepts are still being worked out

An analysis of doping modulated superlattice structures

A new method of growing doping modulated superlattice structures is discussed. This method uses organo-metallic chemical vapor deposition (MO-CVD) with the added feature of controlled plasma in the growth regions. The main objective was to study how the growth environment affected the electronic and optical properties of the superlattice structures. Because a serious safety hazard was discovered in the growth process, no superlattice structures were fabricated and the research on this material had to be terminated. The hazard had to do with the lack of adequate means for the disposal of toxic elemental beryllium

Applications of catastrophe theory in mechanics

A method, using Thom's classification of catastrophes, is described for the analysis of stability of systems whose static behavior is derived from a potential function. Examination of the stability of singular points of potential functions serves to illustrate the nature of the elementary catastrophes which also arise in nonconservative dynamical systems as well as in the static case of potential theory

Method and apparatus for determining optical absorption and emission characteristics of a crystal or non-crystalline fiber

This invention relates generally to spectroscopy and, more particularly, to a method and apparatus for performing spectroscopic analysis of crystal and noncrystalline fibers. The invention provides a complete absorption curve for a material using a crystal fiber which can be more easily produced than the types of samples required for other methods of obtaining substantially the same absorption curve for identical materials

The Validity of Perceptual Recovery Status on Monitoring Recovery During a High-Intensity Back Squat Session

Adaptations to resistance training and subsequent performance can be undermined by inadequate inter-set recovery. This time between sets is often uniformly prescribed based on desired training outcomes; however, there is demonstrative evidence that recovery is highly individualized. Methods typically used to monitor recovery were developed for longitudinal use, making them cost- or time -inefficient within a bout of exercise. If valid, the perceptual recovery status (PRS) scale may be used as an efficient and inexpensive recovery assessment tool to monitor individual recovery as well as appropriately modify rest periods. Purpose: The aim of the current study was to assess the criterion validity of PRS on monitoring recovery during a high-intensity back squat session. Methods: Seven apparently healthy men (age: 21.7 ± 1.4 yrs., height: 1.8 ± 0.1 m., weight: 84.2 ± 11.2 kg., body fat 12.7 ± 2.8 %) volunteered to participate in the two-session study. Study sessions were separated by a minimum of 48 hours. Session one served to gather anthropometrics, familiarize participants with PRS, and conduct a one-repetition maximum (1RM) back squat. Session two was the high-intensity protocol that consisted of five sets of five repetitions interspersed with a five-minute recovery interval at 85% of the preestablished 1RM. PRS was obtained before the first set and during the last 30 seconds of each subsequent recovery period; post-set rating of perceived exertion (RPE) was also collected. A linear position transducer was fixed on the end of the barbell to collect average power of repetitions and fatigue index (FI) calculations for each set. Repeated measures correlations were used to assess the common intra-individual relationships between PRS scores immediately before each set to average power, post-set RPE, and associated FI, respectively. Results: A strong, positive correlation was found between PRS and average power (r[95% CI] = .837 [.671 - 924]; p \u3c .0001); whereas a weak-to-moderate, inverse correlation was found for PRS and FI (r[95% CI]= -.342 [-.639, .044]; p = .07). A moderate-to-strong, negative correlation was found between PRS and RPE (r[95% CI]= -.663 [ -.833, -.378]; p \u3c .0001). Conclusions: Results indicate that PRS can be a non-invasive and immediate means for practitioners to monitor individualized inter-set recovery; however, it may not be a viable option to predict intra-set decrements of performance (FI). PRS tracked very well with a previously established marker of perceptual exertion (RPE), which further strengthens its utility in a practitioner-based setting. Practical Applications: This study provides insight into the practicality of PRS to assess recovery during a high-intensity back squat session. It could be used alongside other measures of performance and recovery monitoring in order to program individualized recovery between sets of lower extremity resistance training in an attempt to maintain performance and desired physiological adaptations

The Validity of Perceptual Recovery Status on Monitoring Recovery During a High-Intensity Back Squat Session

Adaptations to resistance training and subsequent performance can be undermined by inadequate inter-set recovery. This time between sets is often uniformly prescribed based on desired training outcomes; however, there is demonstrative evidence that recovery is highly individualized. Methods typically used to monitor recovery were developed for longitudinal use, making them cost- or time -inefficient within a bout of exercise. If valid, the perceptual recovery status (PRS) scale may be used as an efficient and inexpensive recovery assessment tool to monitor individual recovery as well as appropriately modify rest periods. The aim of the current study was to assess the criterion validity of PRS on monitoring recovery during a high-intensity back squat session. Seven apparently healthy men (age: 21.7 ± 1.4 yrs., height: 1.8 ± 0.1 m., weight: 84.2 ± 11.2 kg., body fat 12.7 ± 2.8 %) volunteered to participate in the two-session study. Study sessions were separated by a minimum of 48 hours. Session one served to gather anthropometrics, familiarize participants with PRS, and conduct a one-repetition maximum (1RM) back squat. Session two was the high-intensity protocol that consisted of five sets of five repetitions interspersed with a five-minute recovery interval at 85% of the preestablished 1RM. PRS was obtained before the first set and during the last 30 seconds of each subsequent recovery period; post-set rating of perceived exertion (RPE) was also collected. A linear position transducer was fixed on the end of the barbell to collect average power of repetitions and fatigue index (FI) calculations for each set. Repeated measures correlations were used to assess the common intra-individual relationships between PRS scores immediately before each set to average power, post-set RPE, and associated FI, respectively. A strong, positive correlation was found between PRS and average power (r[95% CI] = .837 [.671 - vii .924]; p \u3c .0001); whereas a weak-to-moderate, inverse correlation was found for PRS and FI (r[95% CI]= -.342 [-.639, .044]; p = .07). A moderate-to-strong, negative correlation was found between PRS and RPE (r[95% CI]= -.663 [ -.833, -.378]; p \u3c .0001). Results indicate that PRS can be a non-invasive and immediate means for practitioners to monitor individualized inter-set recovery; however, it may not be a viable option to predict intra-set decrements of performance (FI). PRS tracked very well with a previously established marker of perceptual exertion (RPE), which further strengthens its utility in a practitioner-based setting. This study provides insight into the practicality of PRS to assess recovery during a high-intensity back squat session. It could be used alongside other measures of performance and recovery monitoring in order to program individualized recovery between sets of lower extremity resistance training in an attempt to maintain performance and desired physiological adaptations

A comparison of superconductor and manganin technology for electronic links used in space mission applications

The electronic link connecting cryogenically cooled radiation detectors to data acquisition and signal processing electronics at higher temperatures contributes significantly to the total heat load on spacecraft cooling systems that use combined mechanical and cryogenic liquid cooling. Using high transition temperature superconductors for this link has been proposed to increase the lifetime of space missions. Herein, several YBCO (YBa2Cu3O7) superconductor-substrate combinations were examined and total heat loads were compared to manganin wire technology in current use. Using numerical solutions to the heat-flow equations, it is shown that replacing manganin technology with YBCO thick film technology can extend a 7-year mission by up to 1 year

The ultimate efficiency of photosensitive systems

These systems have in common two important but not independent features: they can produce a storable fuel, and they are sensitive only to radiant energy with a characteristic absorption spectrum. General analyses of the conversion efficiencies were made using the operational characteristics of each particular system. An efficiency analysis of a generalized system consisting of a blackbody source, a radiant energy converter having a threshold energy and operating temperature, and a reservoir is reported. This analysis is based upon the first and second laws of thermodynamics, and leads to a determination of the limiting or ultimate efficiency for an energy conversion system having a characteristic threshold

Thermodynamic limits to the efficiency of solar energy conversion by quantum devices

The second law of thermodynamics imposes a strict limitation to the energy converted from direct solar radiation to useful work by a quantum device. This limitation requires that the amount of energy converted to useful work (energy in any form other than heat) can be no greater than the change in free energy of the radiation fields. Futhermore, in any real energy conversion device, not all of this available free energy in the radiation field can be converted to work because of basic limitations inherent in the device itself. A thermodynamic analysis of solar energy conversion by a completely general prototypical quantum device is presented. This device is completely described by two parameters, its operating temperature T sub R and the energy threshold of its absorption spectrum. An expression for the maximum thermodynamic efficiency of a quantum solar converter was derived in terms of these two parameters and the incident radiation spectrum. Efficiency curves for assumed solar spectral irradiance corresponding to air mass zero and air mass 1.5 are presented