Performance Of Individual Components Research Articles

Propulsion System Requirements for Long Range, Supersonic Aircraft

This paper discusses the requirements for the propulsion system of supersonic cruise aircraft that are quiet enough to fly over land and operate from civil airports, have trans-pacific range in the order of 11,112km(6000nmi), and payload in the order of 4545kg(10,000lb.). It is concluded that the resulting requirements for both the fuel consumption and engine thrust/weight ratio for such aircraft will require high compressor exit and turbine inlet temperatures, together with bypass ratios that are significantly higher than typical supersonic-capable engines. Several technologies for improving both the fuel consumption and weight of the propulsion system are suggested. Some of these directly reduce engine weight while others, by improving individual component performance, will enable higher bypass ratios. The latter should therefore also indirectly reduce the bare engine weight. It is emphasized, however, that these specific technologies require considerable further development. While the use of higher bypass ratio is a significant departure from more usual engines designed for supersonic cruise, it is nonetheless considered to be a practical option for an aircraft of this kind.

Dynamic International Diversification Strategies

This paper offers an ex-ante optimization-based comparison among several performance measures over a range of horizons. Apart from its ex-ante nature, the novel features of such a comparison are that it is based on an aggregated performance measure, which allows for an equal start for each of its individual component performance measures and the fact that the comparison is based both on static and dynamic strategies. That is strategies, which incorporate rebalancing decisions up to a given horizon. Dynamic International Diversification Strategies (DIDS) are constructed via ex-ante maximization of aggregate performance measure over different horizons. The example DIDS, considered in the paper, represent a sequence of portfolio decisions on eight country indices (G-7 countries and Switzerland) up to a predetermined horizon from 1 to 52 weeks. Our results suggest that Information ratio based ex-ante optimization criterion dominates the others for horizons longer then 9 weeks. For shorter horizons no measure clearly dominates the others. The relative theoretical contribution of this paper is threefold. First, we use projections-based SDF approach to generate expected returns over different horizons, which to the best of our knowledge is a novel approach. Second, we propose a way to aggregate several admissible performance measures and to determine current international diversification decisions in an attempt to ex-ante optimize an aggregate performance measure. We also motivate the use of decision weights in order to determine which measure outperforms the others in ex-ante terms. An implementation of such a comparison is the main empirical contribution of the paper. Third, we systematically investigate the role of the time horizon on the ex-post realized returns of average static and dynamic international diversification strategies.

Experimental Investigation of a LiCl-Water Open Absorption System for Cooling and Dehumidification

In earlier work, a novel open absorption cycle was proposed, capable of producing both cooling and dehumidification for air conditioning, utilizing low-grade heat. The system, referred to as DER (Dehumidifier-Evaporator-Regenerator), uses ambient air in conjunction with an absorbent solution; the air is dehumidified and then employed to produce chilled water in an evaporative cooler. Alternatively, a portion of the dehumidified air may be used directly for air conditioning purposes. The system thus has the potential to provide both cooling and dehumidification in variable ratios, as required by the load. Computer simulations and theoretical investigations were carried out to analyze and predict the performance of the system. The objective of the present study has been to construct a laboratory system to test the concept, identify problems and carry out preliminary design optimization. The characteristic performance of individual components, analyzed theoretically in the simulation, was studied experimentally. Measurements have provided much-needed realistic data about heat and mass transfer coefficients. The performance of the system has been studied under varying operating conditions. The paper describes the operation of the experimental system and presents the measured data and the resulting transfer coefficients.

Performance utility-analysis of multi-state systems

This paper defines a new utility importance of a state of a component in multi-state systems. This utility importance overcomes some drawbacks of a well-known importance measure suggested by William S. Griffith (J. Applied Probability, 1980). The relationship between this new utility importance and the Griffith importance is studied and their difference is illustrated with examples. The contribution of an individual component to the performance utility of a multi-state system is discussed. Examples show that a meaningful index for measuring the performance of individual components in a multi-state system can hardly be defined in general, without considering the actual values of the utility levels and the distributions of the component-states in the system. An example illustrates how genetic algorithm, simulated annealing, and tabu search can be used in selecting components and defining the position order of components so that the performance utility of a multi-state system is optimized.

Sedation modulates recognition of novel stimuli and adaptation to regular stimuli in critically ill adults.

Responsiveness of critically ill patients is affected by disease and by therapy. Subjective tests of responsiveness (e.g., modified Ramsay score) reflect global integrity of a response arc that includes transduction, perception, classification, and an overt response. The performance of individual components is usually not assessed. To determine whether an association exists among sedative medications and the brain's component information processing and adaptive abilities. Initial observational study of a convenience sample. A surgical intensive care unit of a university hospital. A total of 22 endotracheally intubated, mechanically ventilated patients chemically sedated with narcotics and a benzodiazepine (n = 12), or narcotics and propofol (n = 10) using sedation protocols. None. Patients were presented flashes of light and pulses of sound at fixed or random intervals. Patients receiving low doses of fentanyl and propofol adapted to stimuli presented at fixed intervals and retained the response to novelty. Patients receiving higher doses of those medications did not respond to novelty and responded to stimuli presented at fixed intervals as if they were novel. Patients receiving fentanyl and benzodiazepines had generally weaker responses to all stimuli. Moreover, their responses to fixed and random stimuli were similar. At low doses, the patients retained responses to novelty and adapted to fixed, whereas at higher doses the opposite was observed: the response to novelty was lost and the patients responded to fixed stimuli as if they were novel. These observations suggest that the sedative medications generally accelerate the physiologic decay of stimuli as they engage the brain's information processing and adaptive abilities and further suggest that different sedative medications may have different effects on the brain. Commonly administered sedative medications may alter the brain's biophysical state and thereby modulate specific aspects of the brain's information processing and adaptive functions. These functions can be interrogated even when the patient is seemingly unresponsive. If this observation is confirmed in subsequent prospective controlled randomized trials, electrophysiologic interrogation of the brain's information processing and adaptive capacities could serve as an adjunct to clinical assessment of responsiveness and management of sedative medications.

Dual-task performance in adults with autism

Introduction. Based on previous evidence of executive function deficits in autism, it was hypothesised that people with autism would demonstrate a pattern of spared abilities on the slave system of working memory, although demonstrating an overt deficit of the central executive. Method. The performance of a group of adults with autism (n = 16) and that of a matched control group of healthy volunteers (n = 16) was compared over a range of executive tasks including dual-task performance. Results. The results are broadly consistent with the initial hypothesis: the performance on the dual task of the people with autism was impaired with respect to that of the control group. However, no differences emerged between the two groups in the performance of individual components of the task. Conclusion. All executive tests used in this study predicted the inclusion in the autistic group but there was not a high correlation among executive scores.

Ligature: Component Architecture for High Performance Applications

The increasing feasibility of developing applications spanning nationwide supercomputing resources makes possible the creation of simulations composed of multiple interdisciplinary components and capable of modeling natural and social phenomena of national importance with unprecedented speed and accuracy. However, the potential offered by hardware technology often fails to be fully realized due to the lack of software environments supporting such efforts. Furthermore, the complexity of combining within one application components with different performance characteristics often prevents such applications from achieving required performance levels. The Ligature project at Los Alamos National Laboratory addresses the issue of designing a software infrastructure enabling fast and efficient development of multicomponent applications and that of providing performance guidance to the programmer using this infrastructure. Ligature allows the programmer to define component interfaces specifying how heterogeneous, distributed components can interact within a larger system and provides a reusable infrastructure capable of connecting these components. These interfaces, as well as information about component performance, are accessible through a database. Within this framework, we are trying to understand how information about the performance of individual components and information about performance of the framework can be combined to develop a performance-aware multicomponent application.

Vapor Pressure Deficit Control Algorithm for Plant Studies

A crop to air Vapor Pressure Deficit (VPDcrop-air) control algorithm was developed from analysis of energy balances on bedding plants in a sunlit plant growth chamber (SPGC). The control algorithm was implemented in the SPGC using a computer control interface, and system tests were conducted to determine the performance of individual control components and dynamic response of the system. The completed VPDcrop-air control algorithm was run for several days at typical ambient conditions. Results from these full system tests were analyzed. Algorithm development, performance and possible improvements are discussed.

HLS

As microprocessors continue to evolve, many optimizations reach a point of diminishing returns. We introduce HLS, a hybrid processor simulator which uses statistical models and symbolic execution to evaluate design alternatives. This simulation methodology allows for quick and accurate contour maps to be generated of the performance space spanned by design parameters. We validate the accuracy of HLS through correlation with existing cycle-by-cycle simulation techniques and current generation hardware. We demonstrate the power of HLS by exploring design spaces defined by two parameters: code properties and value prediction. These examples motivate how HLS can be used to set design goals and individual component performance targets. Additionally, these traces are not as susceptible to transient behavior because they are restricted to frequently executed code. Empirical results show that on average this mechanism can achieve better instruction fetch rates using only 12KB of hardware than a trace cache requiring 15KB of hardware, while producing long, persistent traces more suited to optimization.

Studies of hydrogen-induced degradation processes in Pb(Zr1-xTix)O3 (PZT) and SrBi2Ta2O9 (SBT) ferroelectric film-based capacitors

The integration of PZT and SBT film-based capacitors with Si integrated circuit technology requires the use of processing steps that may degrade the performance of individual device components. Hydrogen annealing to remove damage in the Si FET adversely affects both PZT and SBT, although the mechanisms of degradation are different. We have used Mass spectroscopy of recoiled ions (MSRI), X-ray diffraction (XRD), Raman spectroscopy and electrical characterization to study the mechanisms of hydrogen-induced degradation in these two materials. The mechanism responsible for degradation in SBT during hydrogen annealing appears to be hydrogen-induced volatilization of Bi from the near-surface region during film growth. Although there is a similar, but smaller, loss of Pb in PZT, the resulting change in stoichiometry is not responsible for the degradation of the ferroelectric properties. Raman spectroscopy reveals that PZT films exposed to hydrogen exhibit evidence for the formation of polar hydroxyl [OH−] bonds, which can block the movement of ions in the lattice and inhibit polarization. The possible sites for the incorporation of hydrogen are discussed in terms of ionic radii, and crystal structure.

Field Investigation of Landfill Leachate Collection System Clogging

Leachate collection systems (LCSs) are designed to efficiently remove leachate from solid waste landfills. This prevents ponding of leachate on the liner system, thus minimizing leachate migration to the environment. The depth of leachate on the liner is a regulatory design standard (<30 cm). The permeability of the LCS is a primary factor in determining the collection efficiency. The potential of LCS drainage materials (sand, gravel, and geotextiles) to clog as a result of biological growth and particulate clogging is an important issue that should be addressed in landfill design. The performance of individual components is known to decline in laboratory testing; however, little is known about permeability under true landfill conditions. Testing the drainage material in excavated LCSs for clogging is important in determining the extent to which individual components fail. Research was conductd to characterize the physical and chemical nature of drainage media collected from a 6-year-old leachate collection system. Hydraulic conductivity, grain size distribution, volatile solids, and metals analysis were performed on drainage sand samples to determine if any clogging had occurred. Likewise, permittivity tests were performed on geotextile samples. On average, the sand drainage layer permeability was reduced from 1.85 x 10\u–² to 1.23 x 10\u–² cm²/s (33% reduction in flow). Likewise, the geotextile samples experienced an average decrease in permittivity from 6.4 to 3.3 s\u–¹ (48% reduction). Inspection of these results indicates that although the drainage media experienced a reduction in permeability and permittivity compared to original conditions, both the sand and the geotextile maintained their capacity for high flow rates, resulting in an acceptable increase of head on the liner.

Heuristic method for evaluating COIL performance

A heuristic methodology is described that was developed to evaluate the chemical efficiency of high-power chemical oxygen iodine laser (COIL) devices and its application to the specific evaluation of the U.S. Air Force Phillips Laboratory's RotoCOIL laser. A heuristic equation that forms the basis of this methodology and describes the COIL energy flow, energy losses, and power extraction using measured data, code results, and empirical relations is presented. Using this equation and bounding values for some of its terms, it is shown that for the RotoCOIL performance data the experimentally measured average O 2 ( 1 Δ) yield of 0.40 is nearly 38% below that which would be consistent with the measured extraction power. By relating terms of the heuristic equation to performance of individual components of the COIL system, it is concluded that nearly 50% of the efficiency loss for the RotoCOIL laser derives from oxygen generator and delivery losses, whereas 15% is from nozzle inefficiencies and 11% from resonator losses.

Doppler global velocimetry: problems and pitfalls

A 1D Doppler global velocimeter (DGV) system was designed and constructed. During the evaluation of this system, inaccuracies were observed which could be attributed to the performance of many individual components. Items requiring evaluation included the performance of video cameras, the transfer lens, the beam splitter, the ALF cell construction, the absorption line filter (ALF) cell charging, and video recording computer boards. Descriptions of the problems and corrections are detailed.

Theoretical and Experimental Evaluation of FRP Components and Systems

Two bridge superstructural systems and two other floor systems are constructed and tested under concentric static loads using fiber reinforced plastic (FRP) shapes. Structural performance of individual FRP components is established through three‐ and four‐point bending tests. Structural efficiency of each system is analyzed in terms of joint efficiency, transverse load distribution, composite action between FRP components, and maximum deflections and stresses. Theoretical prediction of system performance is conducted by the orthotropic plate theory, finite‐element method, and a method to predict beam stiffnesses based on simplified classical lamination theory (CLT). The correlation between theoretical and experimental results is good and reveals that the simplified CLT can be effectively used in future designs. The bridge and floor systems tested herein had undergone deflections smaller or at the most equal to the allowable (L/1,000 and L/360, respectively) for loads larger than the corresponding allowabl...

The transfer of superfluid helium in space

The Superfluid Helium On-Orbit Transfer (SHOOT) Flight Demonstration waspart of the space shuttle STS-57 mission in June, 1993. The experiment objectives included: transfer of superfluid between two dewars m a low gravity environment at different flow rates; operation of two different liquid acquisition devices within the dewars; liquid/vapor phase separation for normal liquid helium as well as superfluid at varying venting rates; accurate mass gauging and flow metering; and autonomous control of the transfer process by an expert system aboard a computer on the shuttle. This paper summarizes the findings of the SHOOT experiment and the performance of individual components, with particular emphasis on the anomalous behavior of one of the phase separators.

The NPL standard humidity generator: an analysis of uncertainty by validation of individual component performance

The NPL standard humidity generator-the reference for traceable humidity calibrations in the United Kingdom-has been validated by assessment of the performance of individual components of the generator system. The investigation has explored the effects of saturator efficiency, temperature conditioning of the gas, desorption, leaks, pressure variation and other factors that contribute to the uncertainty in dew-points generated by this instrument. The results of these experiments have led to some improvements in the design of the standard. Repeatability of overall performance has been monitored over a period of two years. The improvements in design, together with better characterization of the performance of the instrument, have enabled a smaller uncertainty in generated dew-point to be assigned. This uncertainty is now +or-0.05 degrees C dew-point in the middle of the operating range, rising to +or-0.08 degrees C and +or-0.15 degrees C dew-point at the upper and lower extremes of the range: +80 degrees C and -75 degrees C dew-point respectively.

Operation data of a directly fired absorption heating unit with periodically operating absorber

AbstractThis contribution presents the layout, construction, and experimental investigation of operation behaviour of a directly fired absorption heating unit with periodically operating absorber. The working system is CH3OH‐LiBr/LiOH. The unit is designed to generate a maximum heat load of 10 kW. The field of application is mainly in domestic heatIng. A special feature of the absorption heating unit is the provision of the major part of required process heat in the heat pump mode of operation with high efficiency. At extremely low ambient air temperatures, heat is supplied in the direct mode. A numerical simulation routine is also described. The simulation program describes both steady‐state and dynamic processes in the unit. With models for each component, the performance of individual components can be studied and optimized. The results presented here consist of the first experimentally obtained efficiencies in direct heating mode, results of numerical simulation of the component generator, and a comparison of measured and predicted characteristic system temperatures.

Light Use, Water Uptake and Performance of Individual Components of a Sorghum/Groundnut Intercrop

SUMMARYThe productivity of each component of a sorghum/groundnut intercrop and its constituent sole crops is determined in terms of a ‘Crop Performance Ratio’ (CPR) defined as the productivity of an intercrop per unit area of ground compared with that expected from sole crops sown in the same proportions. The CPR allows productivity, intercepted radiation and seasonal transpiration to be compared so that conversion coefficients for radiation (e; g MJ−1) and dry matter/water ratios (q; g kg−1) can be calculated for each intercrop component and its constituent sole crops. In this experiment, CPR for total dry weight in the intercrop was 1.08 and that for reproductive yield was 1.27. These advantages in overall productivity and yield were typical of those reported elsewhere for sorghum/groundnut intercrops. The proportional increase in total dry matter in the intercrop was largely a result of its greater interception of radiation. The further advantage in reproductive yield was a consequence of an improved harvest index in the sorghum component of the intercrop (0.64) compared with that of its sole crop counterpart (0.55).

Light Use, Water Uptake and Performance of Individual Components of a Sorghum/Groundnut Intercrop

SUMMARYThe productivity of each component of a sorghum/groundnut intercrop and its constituent sole crops is determined in terms of a ‘Crop Performance Ratio’ (CPR) defined as the productivity of an intercrop per unit area of ground compared with that expected from sole crops sown in the same proportions. The CPR allows productivity, intercepted radiation and seasonal transpiration to be compared so that conversion coefficients for radiation (e; g MJ−1) and dry matter/water ratios (q; g kg−1) can be calculated for each intercrop component and its constituent sole crops. In this experiment, CPR for total dry weight in the intercrop was 1.08 and that for reproductive yield was 1.27. These advantages in overall productivity and yield were typical of those reported elsewhere for sorghum/groundnut intercrops. The proportional increase in total dry matter in the intercrop was largely a result of its greater interception of radiation. The further advantage in reproductive yield was a consequence of an improved harvest index in the sorghum component of the intercrop (0.64) compared with that of its sole crop counterpart (0.55).

Incompatibility of Building Components

The interaction of building components is difficult to predict. In the fast‐paced industries of design and build, the time is not often allotted to research the performance of individual building components, much less the interaction of components. To exacerbate the situation, specified materials are often improperly substituted with inferior or inappropriate products. Furthermore, the quality of the delivered materials is often not checked. The use of incompatible, improper, or inferior materials typically results in performance failures, which are often never realized by the designer, contractor, and owner. This paper presents a case study of the corrosion failure of galvanized roof components in a ballasted single‐ply roof system. The case study illustrates what can go wrong in the construction of a typical facility, and what steps were taken to identify positively the cause of a particular problem prior to the consideration of a permanent repair.