Constant Energy Input Research Articles

Unique adaptations of the metabolic biochemistry of tunas and billfishes for life in the pelagic environment

Virtually all characteristics of tunas and billfishes reflect their highly charged lifestyles as apex predators in the oceanic pelagic environment. The adaptations they possess for efficient and rapid swimming, efficient and rapid food processing, turnover of nutrients and storage and mobilization of internal fuel supplies, and for rapid recovery rates, are discussed. Overall, tunas and billfishes are designed for high performance, at both sustainable and burst swimming speeds, but there are several differences between tunas and billfishes. Tunas' aerobic metabolic capacities exceed those of ectothermic fishes, including billfishes and other scombrids, by virtue of their elevated red muscle temperatures, and because heart and white muscle aerobic capacities are significantly greater in tunas. The adaptations for high performance involve some costs, including the need for a constant high energy input to sustain high metabolic rates, high activity levels, and endothermy, Yet, tunas and billfishes have adopted successful lifestyles, as evidenced by their large numbers and biomass within the marine environment. Although our knowledge of these fishes has increased dramatically during the past 15 years, there are major gaps in our understanding of the metabolic biochemistry and physiology of these fishes, and these are highlighted so that additional research can be directed towards filling these gaps.

Optical energy considerations for diode-clamped smart pixel optical receivers

We calculate the switching time as a function of optical energy for a single-stage smart pixel receiver. We find that operating the receivers dynamically using modelocked pulses is the most energy-efficient method of operation. We also show that the receivers no longer operate with constant optical input energy, like the symmetric self electro-optic effect device (S-SEED), but rather the product of the required optical energy and the switching time is constant, as a result of the introduction of electrical voltage gain.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Phonon emission by hot electrons in delta -doped GaAs

Simultaneous measurements of current-voltage characteristics and time-of-flight spectra of emitted phonons were performed for delta -doped GaAs at 2 K. The phonon flux consists of two parts: a narrow signal due to the ballistic arrival of the acoustic phonons and a broad signal arising from the decay products of optical phonons emitted by hot electrons. An increase in conductivity and a decrease in the time-integrated narrow signal divided by the input power are observed at moderate field strengths. Both features are explained by the real-space transfer of electrons from the quantum wells to extended states. At high fields the conductivity decreases whereas both phonon fluxes per input power increase. These effects are suggested to be due to the transfer of hot electrons from the Gamma band edge to the L valleys assisted by the deformation potential interaction with phonons. The dependence of the position of the maximum of the narrow signal on the duration of the voltage pulses at constant input energy indicates the presence of inelastic phonon-phonon interactions and the formation of the hot spot.

Bolometric light curve of SN 1987A - Results from day 616 to 1316 after outburst

view Abstract Citations (61) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Bolometric Light Curve of SN 1978A: Results From Day 616 to 1316 After Outburst Bouchet, P. ; Danziger, I. J. ; Lucy, L. B. Abstract We present the bolometric light curve of SN 1987A from day 616 to day 1316 after outburst. This light curve is based on infrared J to Q_0_ broadband photometry obtained at ESO La Silla and a blackbody extrapolation for the far infrared flux beyond 20 microns, where no observations are available. Under the assumption that such an extrapolation is correct, roughly 80% of the ultraviolet-optical-infrared flux after day 650 is extrapolated: the reported luminosity is then not only affected by large uncertainties, but it is also mainly based on a theoretical model which cannot be confirmed by observational evidence. A positive detection achieved at 1.3 mm suggests that free-free emission is probably contributing to the energy spectrum. In spite of the uncertainties, our data with the assumption made for the FIR extrapolation clearly show that at least until day 791, the bolometric light curve decreases at the exponential rate reported for earlier epochs, levels off from about day 900 to 1050 above the linear extrapolation of this exponential decrease, and then resumes a slow decrease still above the luminosity predicted by models based on radioactive decays. The implications of such a behavior are discussed, and we show that our results are consistent with an energy input, absorbed and reradiated by dust in the ejecta, from a variable (4 x 10^37^ ergs s^-1^ < L_Bol_ <1.5 x 10^38^ ergs s^-1^) undetected extra energy source, whose origin is still unclear. Our results are also marginally consistent with a constant extra energy input of approximately 10^38^ ergs s^-1^. Publication: The Astronomical Journal Pub Date: September 1991 DOI: 10.1086/115939 Bibcode: 1991AJ....102.1135B Keywords: Infrared Astronomy; Light Curve; Stellar Luminosity; Supernova 1987a; Emission Spectra; Energy Spectra; Infrared Photometry; Neutron Stars; Radioactive Decay; Spectral Energy Distribution; Astrophysics; NEBULAE: SUPERNOVA REMNANTS; INFRARED: SOURCES full text sources ADS | data products NED (2)

The late-time bolometric luminosity of SN 1987A

We present infrared photometry of SN 1987A in the J, H, K, L, M, 10, and 20 micron filters through day 1352 since the explosion of the Supernova. We find that both the optical and mid-infrared magnitudes are slowly leveling out through day 1352 after their rapid decline in brightness during the epoch of dust formation. The near infrared colors (V-J, V-H, and V- K&gt; initially reddened after dust formation around day 500, but by days 900-1000, they began to evolve to the blue, perhaps due to the thinning of the dust. Optical spectra obtained through day 1150 show no evidence for a sudden drop in the optical emission-line luminosities. This suggests that the region of optical emission has not undergone the so- called "infrared catastrophe," when the cooling of the ejecta becomes dominated by the infrared fine-structure lines, at least in the case described by the simple models of Fransson &amp; Chevalier [ApJL, 322, L15 (1987)]. More complicated models where the higher density regions are cooled by the fine-structure lines at the same time that the nebular dust is thinning could be qualitatively consistent with the data. The infrared data have been combined with optical photoelectric and CCD UBVRI photometry obtained at CTIO to study the temporal evolution of the bolometric luminosity of SN 1987A. By day 1000, another source of energy beside the radioactive decay of ^56^Co is needed to explain the slow leveling off to the bolometric luminosity decline. We can formally fit our data with the following energy sources: 5+/-1 times the predicted ("solar") amount of ^57^Co/^56^Co;10+/-3 times the predicted amount of ^44^Ti; or a constant energy input of 37.3+/-0.15 dex (log_10_(ergs s^- 1^)]. The energy input is unspecified; it could be a pulsar, light echo, or other unidentified energy source. Only the enhanced ^57^Co/^56^Co provides a good fit at all times to the data. The enhanced ^57^Co, however, is in conflict with published hard x-ray and infrared spectral data. A careful reanalysis of the uncertainties in the observed hard x-ray and ultraviolet-optical-infrared fluxes, and the model predictions, suggests that all the data can be fit by the energy deposition from 0.075M_sun_ of ^56^Ni, a ^57^Co/^56^Co between 2.5 and 4 times "solar," and "solar" ^44^Ti.

Does deterministic chaos imply intermittency in fully developed turbulence?

A Fourier–Weierstrass decomposition of the velocity field is introduced. The admitted number of real amplitudes is 572 or 836. They are determined numerically from the Navier–Stokes equation including viscosity, driven by constant energy input stirring the largest eddies only. In another calculation, the energy input is provided by an external shear. The Reynolds number Re is about 106, the inertial range comprises about 2 decades, and there are 11 levels of successively decaying eddies. The hierarchical mode ansatz thus allows for a state of high turbulence, which usually is inaccessible numerically. Deterministic chaos is found on all scales. The mean values of the amplitudes scale with the eddy size r as rζ with ζ very near 1/3. Expected deviations δζ=ζ−1/3, as one typical signature of intermittency, are very small only, well compatible with none at all. So, despite stochasticity (chaos) in the Fourier–Weierstrass decomposition with a tractably restricted set of plane waves, intermittency in the velocity scaling cannot be found. This changes if, in addition to temporal chaos, a spatial branching of the eddy decay process is also admitted.

Closing remarks: geophysical

The search for a connection between solar variability and the Earth’s climatic variations has given rise to much controversy: given the great instabilities of the atmosphere and the relatively short span of accurate observations this was inevitable. Meteorologists, very conscious of the complexity of modelling the atmosphere, even assuming a constant energy input, have often been very critical of claims to have detected the solar cycle, and even hostile to the search for one. Now, as so often is the case in science, important evidence has come from an entirely different field; 14 C dating. One can therefore have sympathy with the distinguished meteorologist who, when informed of the 200-year period in the Sun inferred from this work and its possible effect on the climate, said ‘Dear Professor Suess, you must understand that the Sun has nothing to do with the climate.’ I trust that it is not an apocryphal story!

AN INVESTIGATION OF FATIGUE CRACK GROWTH IN A DUCTILE MATERIAL AT HIGH GROWTH RATES

Abstract— Investigations into tearing‐fatigue have been performed using three point bend specimens made of mild steel. A computer controlled testing machine was used which could maintain constant cyclic displacement ranges, or constant cyclic energy input ranges, and hence provide a range of crack tip driving force conditions. Fatigue crack growth rates were measured and compared with the predictions of a model based on the linear summation and non‐interaction of fatigue and ductile tearing growth rates. The effects of fatigue crack growth on monotonic crack growth resistance properties were investigated. It is concluded that there is no significant interaction between these two crack propagation mechanisms in this steel. Crack growth rate equations governing propagation in the tearing‐fatigue regime are given.

Light-curve models for supernova SN1987A in the Large Magellanic Cloud

Neutrino bursts from the supernova SN1987A have been reported1–3 which provide qualitatively new information as to the time interval between the core collapse and the optical flaring of the supernova up to about 6 mag4. The interval that we take as three hours1,2 imposes conditions on the radius of the progenitor star and the energetics of the explosion. As for the brightness and its time change, the relatively less bright visual magnitude at the plateau in the light curve during the initial eight days or so (refs 5, 29) as well. The subsequent light curve after eight days is quite unique; the bolometric luminosity increases until ∼65 days (ref. 29) but thereafter it seems to level off gradually (J. Walsh and R. Stathakis, personal communication; M.A. Dopita, personal communication). To maintain the bolometric luminosity of the star means that certain conditions should be imposed on the energy source. By computing the propagation of shock wave, the subsequent expansion of ejected matter and the optical light curve, we find that the early light curve can be accounted for by the diffusive release of energy deposited by the shock wave, that the progenitor's radius should be as small as ∼(1–3) × 1012 cm, and that the explosion energy per unit mass should be relatively large, ∼(2–3)× 1051 erg for the ejected matter of 7–10 M⊙. The light curve after eight days is well reproduced by using a model with constant energy input. The energy input may be due to the activity of an embedded pulsar. The light curves calculated by invoking the radioactive decay of 56Ni and 56Co are less satisfactory in accounting for the nearly flat portion observed after 65 days. Supposing Sk–69 202 is the progenitor of SN1987A13,14, its explosion energy should be >2×l051erg; this suggests that a prompt shock mechanism forms a neutron star.

Scaling and performance of CO2 lasers at supra-atmospheric pressure

The performance of a compact uv photo-preionized TE laser is studied in the pressure range 1–5 bar. As the pressure is increased, the laser pulse shape is little altered, but both the peak power and the total output pulse energy increase significantly with pressure, even for constant input electrical energy. For various gas mixtures and excitation source capacitors the measurements suggest approximate output energy scaling with the product of the source charge per unit electrode area [C.m−2] and the molecular partial pressure [CO2+N2+CO]. This is explained in terms of the pressure-dependent discharge impedance. An input-energy-related discharge instability limits the optimum laser pressure to 1.5–2.5 bar, and we show that, at constant input energy, the instability boundary depends on the molecular partial pressure alone. The pre-ionization photo-electron yield varies negligibly with pressure, but the discharge tolerance to added oxygen decreases asp−3 top−4, dependent on gas mixture. Nevertheless sealed operation for >105 shots has been obtained with a 5% CO2∶5% CO∶3% N2∶2% H2∶85% He gas mixture at a total pressure of 5 bar.

Polymerization of ADP-actin and ATP-actin under sonication and characteristics of the ATP-actin equilibrium polymer.

Polymerization under sonication has been developed as a new method to study the rapid polymerization of actin with a large number of elongating sites. The theory proposed assumes that filaments under sonication are maintained at a constant length by the constant input of energy. The data obtained for the reversible polymerization of ADP-actin under sonication have been successfully analyzed according to the proposed model and, therefore, validate the model. The results obtained for the polymerization of ATP-actin under sonication demonstrate the involvement of ATP hydrolysis in the polymerization process. At high actin concentration, polymerization was fast enough, as compared to ATP hydrolysis on the F-actin, to obtain completion of the reversible polymerization of ATP-actin before significant hydrolysis of ATP occurred. A critical concentration of 3 microM was determined as the ratio of the dissociation and association rate constants for the interaction of ATP-actin with the ATP filament ends in 1 mM MgCl2, 0.2 mM ATP. The plot of the rate of elongation of filaments versus actin monomer concentration exhibited an upward deviation at high actin concentration that is consistent with this result. The fact that F-actin at steady state is more stable than the ATP-F-actin polymer at equilibrium suggests that the interaction between ADP-actin and ATP-actin subunits at the end of the ATP-capped filament is much stronger than the interaction between two ATP-actin subunits.

The predicted performance of a mixed-flow grain drier

A computer simulation was used to examine the effects of drying air temperature, air flow rate and drier size on the predicted performance of a mixed-flow grain drier. Performance was analysed in terms of grain throughput, specific energy consumption, and maximum and output grain temperatures. Increasing the energy input to a given size of drier, by increasing either air temperature or air flow rate, increased grain throughput. The use of higher temperatures gave lower specific energy consumptions, whereas higher air flows increased specific energy consumption. For a constant energy input, increasing either the drier size or number of grain beds in the drier improved performance.

The sea breeze with mean flow

AbstractA quasi‐geostrophic mean flow can form the basic state upon which a sea breeze is superimposed; a model is described. With a mean flow perpendicular to the coast the speed of the sea breeze front is shown to be a linear function of the onshore component of the mean flow. When a constant mean flow is introduced the general structure of the sea breeze is unchanged. In particular, for a constant energy input the intensity is also unaltered. In contrast, a shear changes the general qualitative structure but leaves the speed of the front and the intensity of the sea breeze unchanged. These features are consistent with the available potential energy of the system and a constant transfer, per unit area, of this into kinetic energy. Model results and other studies are discussed.

The Thermodynamic Origin of Ecosystems

A general theory of the origin of ecosystems in thermodynamic terms is developed. Regular fluctuations in the availablility of energy give rise to dissipative structures in systems where the boundary constraints preclude the development of the equilibrium state. Dissipative structures are patterns in the energy flow that cease to exist when the energy flow ceases; when in the vicinity of their equilibrium position, they tend to a state of least entropy production. The ecodeme, or group of like individuals interacting equally within the constraints of the niche boundaries, exhibits the characteristics of a dissipative structure. The characteristics of a dissipative structure demand that it actively acquire and conserve energy, and that it exhibit organization. Organization implies the existence of order and a goal or end point; order is represented by uniformity of individuals in the ecodeme, the goal is represented by the state of least entropy production. Within the ecosystem ecodemes interact so that the system as a whole tends to proceed to a state of maximum entropy and maximum entropy production rate. In this way the ecosystem functions as a series of coupled shock absorbers and tends to assume a state of maximum steadiness or least oscillation. The condition of least entropy production and least oscillation can be most clearly recognized in the dominant species at the climax in an autonomous system. An autonomous system is one that approaches the closed thermodynamic condition. The biosystem or total biological complex within the biosphere, being completely autonomous, tends towards a state of maximum steadiness within the constraints of the energy input regime. Migration patterns thus develop in response to the reduction of local instabilities caused by local differences in energy input.As organisms develop in response to fluctuations in energy availability, greatest diversity exists where the excitation of the system is most heterogeneous. Heterogeneity of excitation develops in environmental conditions that tend to be most homogeneous in their overall pattern. The more homogeneous and the greater the total amount of energy available annually, the greater the capacity to break up into a large number of minor fluctuations under the influence of the trend to increased entropy. Heterogeneity is developed under the influence of daily changes in availability and the development of physical structure in the ecosystem. Maximum diversity, therefore, is attained in those geographical regions in which wet tropical forest develops. As the heterogeneity of the overall climatic pattern increases and total energy available decreases with increasing latitude, so diversity tends to be reduced, and individual biomass, relative to input, increases.Evolution results from continuous self-acceleration of the energy flow under conditions of constant energy input. Self-acceleration results from the tendency towards ever-increasing dispersal of the energy within the ecosystem as expressed in ever-increasing diversity; increasing diversity causes an increase in the rate of energy flow. Under these circumstances the energy flow to each ecodeme tends to become attenuated so that there is selection for improved energy acquisition to maintain a satisfactory solution to the acquisition–conservation integral. This increase in acquisitive capacity demands an increase in complexity and a further increase in rate of energy flow.These concepts, by way of validation, are examined in the context of stability, energy transfer, natural selection, fitness, and the observable characteristics of evolution.Key words: thermodynamics, ecosystem, energy flow, dissipative structure, ecodeme, organization, order, diversity, stability, energy transfer, fitness, reproduction, group selection, natural selection, evolution

CO&amp;lt;inf&amp;gt;2&amp;lt;/inf&amp;gt;laser excited by a long pulse capacitively coupled discharge

A CO 2 TEA laser is excited by a preionized discharge through dielectric electrodes with single pulse durations of 100-300 ns (FWHM). For constant input energy, output energy and efficiency are found to increase with pulse duration giving rise to a maximum enhancement of approximately 20 percent over the range tested. An output comparable to metallic electrode devices was obtained. Optimum performance was achieved for a total circuit inductance on the order of 2μH.

Characteristics of CO2 TE-amplifiers with different UV preionization at superatmospheric pressure with doping additives

The attainable maximum pressure and the small signal gain are compared at pressures up to 3 bar in a TE-CO2 laser amplifier with two preionization systems. It is found that doping with tripropylamine increases the attainable pressure for glow discharges but decreases the small signal gain. At slightly superatmospheric pressure and low doping amount the simple lamberton-Pearson device gives the best results. For constant input energy the inversion grows with increasing total pressure.

Noise and Vibration Analysis of an Impact Forming Machine

The mechanism of noise and vibration generation in an impact forming machine is investigated using Fourier Transform methods. Noise, vibration, and load measurements have been correlated for a fixed input energy and the sound field around the machine investigated. The measured results are compared with those predicted by a lumped parameter computer model for determining the normal modes of vibration of the machine structure and the moving platen. It is found that the major proportion of the noise energy is generated in the impact area and the dominant source of noise is the free vibration of the structure. Further contributions are observed due to the excitation of the structure by the impact force. For a constant input energy the noise and vibration levels increase as the billet height for simple upsetting is reduced.

Sorting Blueberries for Quality by Vibration1

Abstract A method is described and test results reported for sorting blueberries with low-frequency vibration. Separation was dependent on fruit firmness which is affected by roughness of handling and other softening factors. Firmness, as measured by compressing blueberries 0.2 cm between flat plates, statistically explained 58 to 72% of the variation in frequency for removal of berries from a vibrating trough with constant energy input. When comparing ripeness with frequency for sorting, light transmittance (∆OD; 740-800 nm) values, which indicate anthocyanin pigment concentration, explained only 10% of the variation in sorting frequency. Berries of several cultivars and harvest dates were vibration sorted and tested for susceptibility to decay. Sorting frequency statistically explained 75% of the variation in decay level. Thus, the vibration method should be suitable for sorting blueberries into groups of different shelf life.

Decelerative Cutting of 6061-T9 Aluminum, 65-35 Brass, and TPE Copper With Constant Impact Energy

The chip formation process during metal cutting in which the cutting velocity is permitted to decrease freely is examined from an experimental standpoint. Metal cutting data are obtained from a specially constructed decelerative cutting apparatus for 6061-T9 aluminum, 65-35 brass, and TPE copper under the test conditions of constant energy input and variable initial momentum, velocity, and rake angle. The overall mechanics of chip formation are found to be essentially identical to that for the steady state, including a similarity of the dynamic velocity dependence of cutting forces to their velocity dependence in steady state tests. A complex velocity dependence is noted for 6061-T9 Aluminum. Further evidence of the constancy of the dynamic shear stress is presented. Kinetic energy and momentum are found to have no significant effects upon the chip formation process.

The Distribution of Radiation from Relativistically Expanding Radio Sources

view Abstract Citations (10) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Distribution of Radiation from Relativistically Expanding Radio Sources De Young, D. S. Abstract The distribution of synchrotron radiation in a relativistically expanding source is considered as seen by a distant observer. A variety of initial conditions, optical depths, and geometries are examined, including sources of constant energy input, blast waves, and jets. It is found that double or core-and-halo sources with apparent expansion velocities in excess of the velocity of light can result from natural geometries and actual expansion rates less than c. The results are compared with observations of 3C 279, 3C 273, and 3C 120, all of which exhibit possible "superrelativistic" expansions. Publication: The Astrophysical Journal Pub Date: November 1972 DOI: 10.1086/151734 Bibcode: 1972ApJ...177..573D full text sources ADS |