Total Energy Flow Research Articles

Studies in energetics and population dynamics of the water scorpion, Nepa rubra L. (Insecta: Hemiptera).

There is little information on the energy turnover of carnivorous water insects. This study concerns the energy flow through an imaginal population of the water scorpion, Nepra rubra, a water bug common in the lake "Neusiedler See" in eastern Austria.Population dynamics, production and respiration were determined from 1972 to 1975 under conditions as natural as possible. The cumulative sum of production energy is small, comprising 179.3 J for ♂♂ and 223.8 J for ♀♀, with an additional 241.6 J for reproduction. Food reserves, particularly fat accumulated in the fat body during prediapause, are utilized in winter and extensively by females during breeding the next spring. The largest fat content indicated for ♂♂ was 4.64 mg and 9.64 mg for ♀♀ (crude lipoids).The respiration rate is high even in winter. It is assumed that at this time oxygen is utilized exclusively for the oxydation of fats. Cumulative respiration energy for the adult stage was 2000.2 J for males and 3221.4 J for females. Total annual energy flow through a population of adults was about 663 kJ/100 m2 of which 596 kJ (=89%) were applied to respiration and 67 kJ (=11%) to production.

The relationship of energy flow at the magnetopause to geomagnetic activity

Properties of the energetic electron (E ≳ 200 keV) magnetopause layer along the distant magnetotail have been studied with Caltech instrumentation aboard IMP‐8 for approximately 60 spacecraft orbits. The cross‐sectional area of the layer appears to increase by a factor of ∼ 5 with increasing geomagnetic activity, and the average unidirectional electron flux within the layer increases by a factor of ∼ 4. The energy carried by electrons ≳ 200 keV ranges from ∼ 1014 ergs sec−1 to ∼ 1015 ergs sec−1. Extrapolation to include all electrons > 1 keV suggests total energy flow ranging from ∼ 3×1015 ergs sec−1 at quiet times to ∼ 5×1018 ergs sec−1 at magnetically disturbed times.

Materials for Advanced Energy Technologies

The recovery and processing of industrial materials required about 16 percent of the total U.S. energy consumption in 1974. The interdependence of energy and materials has been increasing and will continue to increase as the more easily won raw materials are exhausted and as the energy conversion and utilization schemes become more sophisticated. The author stresses the materials technology that will be required in major developing systems for extracting, converting, distributing, and using energy--emphasizing that development of suitable materials often takes many years. A detailed schematic is shown that represents the energy sources; methods of processing, conversion, transmission, and storage; and forms of fuel energy that may exist in the near term, up to about 1990. The schematic indicates that uranium, gas, coal, and oil will probably still contribute more than 95 percent of the total energy flow in 1990. For the near term, coal liquefaction, coal gasification, water-moderated reactors, municipal waste, high-temperature turbines, and geothermal will contribute up to 5 percent. For the midterm, 1990 to 2005, fast breeder reactors, photovoltaic conversion of solar energy to electricity, MHD, and flywheels should contribute significantly. The projections for controlled fusion in the year 2005 and beyond are summarized. The magnitude ofmore » the problem involves sustained effort from universities, industrial organizations, and government laboratories, guided by close interplay with energy system designers. (MCW)« less

Energy-economic theory and mathematical models for combining the systems of man and nature, case study: The urban region of Miami, Florida

This paper presents a study of the urban region of Miami, Fla. with consideration of energy flow and the relationship between energy theory and economics. Much of this work is based on the theories and work of Dr Howard T. Odum at the University of Florida. A theory of energy quality is presented which is an attempt to relate energies of different concentrations in their ability to do work. This theory allows comparison of the systems of man and nature. Another theory is proposed which seeks to describe the ability of a region to compete based on its flows of natural and fossil fuel energies. Economic, natural system, and energy data were compiled for the Miami urban region from 1950–1972. Cross-correlation of this data showed significant levels of correlation between the rate of change of fossil fuel use and the rates of change of population, budget, sales tax, income, building structure, and number of telephones. Calculation of several urban indicators for 1972 showed a fossil fuel energy density of 300 kcal/m 2/day in the urbanized area, a per capita energy consumption of 53.8 × 10 6 kcal/capita/year, a ratio of natural to fossil fuel energies of 0.25, a developed area of 260 miles 2 (673.4 km 2), and a rate of development of 6.5 miles 2 (16.8 km 2) per year. An overall model of Miami is presented with flows and storages quantified for 1972. Based on this model a simpler model was simulated on an analog computer. This model consisted of a system of first-order in time, non-linear differential equations which included fossil fuel energy flows, main economic flows, external price functions, building structure, natural energies, and population. This model was simulated for several linearly increasing future price functions and several sets of future energy functions. Natural energies within the region were calculated by determining the land areas associated with various ecosystem types. Estimating the productivities of these systems on a per area basis allowed calculation of total energy flows. The energies associated with winds, tides, waves, and fresh/salt water concentration gradients were also determined. It was found that the ratio of natural to fossil fuel energy changed from 1.77 in 1950 to 0.25 in 1972.

Model Estimation of Energy Flow in Northwestern Coniferous Forest Bird Communities

A simulation model developed in the Grassland Biome Program of the US/IBP is applied to data gathered in the Coniferous Forest Biome Program to estimate the magnitudes and patterns of energy flow in breeding bird populations in Northwestern coniferous forests. Six stands along a moisture—temperature gradient in the central Oregon Cascades supported breeding avifaunus of 7—15 species, with standing crops of 223—526 g/ha. Total energy flow through these avifaunas during the April—October breeding season was estimated at roughly 10 kcal m—2 season—1 in the low—elevation, moderately xeric stands; 12 kcal m—2 season—1 in the high—elevation stands; 17 kcal m—2 season—2 in a mesic floodplain stand; and 21 kcal m—2 season—1 in a midelevation transitional stand. About 1% of the seasonal energy flow was channeled into production, while reproduction—related processes accounted for 15%—16% of the total energy intake. Thermoregulation required 13%—19% of the seasonal total, with the higher relative costs associated with the cooler, higher elevation stands. Foiliage—gleaning bird species accounted for the greatest proportion of the energy intake at most stands, but within this guild the importance of granivorous opportunistic species generally increased through the stand sequence as the growing season became shorter and environmental conditions more severe.

Emergence of Chironomidae (Diptera) from Char Lake, Resolute Northwest Territories

Quantitative data, using [Formula: see text]-m2 submerged traps, were obtained on the six common chironomid genera in Char Lake, at latitude 74°56′ N. Emergence of each species was highly synchronized and in 1972 occurred partly or wholly beneath ice. Each species had different emergence distributions compared with depth, with only two species constituting virtually the entire emergence in the deep sediment zone below 15 m, Emergence per square meter was highest in the shallow areas and the bulk of emergence came from the upper third of the lake. Total emergence was 690 individuals m−2 lake surface in 1971, equal to 0.143 g m−3 year−1 or 0,798 kcal m−2 year−1; this is equal to 0.5% of the lake's total energy flow.

Consumption of Primary Production by a Population of Kangaroo Rats (Dipodomys Merriami) in the Mojave Desert

The energy requirements for a population of kangaroo rats in the Mojave Desert were estimated indirectly. Energy expenditure for maintenance was 84.1 megacal ha—1yr—1. Total energy expenditure for growth was 1.4 megacal ha—1yr—1, half of which was secondary productivity. Secondary productivity was 0.8% of the total energy flow. This percentage of the total energy flow is lower than for nondesert rodents and may be due to the low productivity of the desert areas in which D. merriami is found. The diet of D. merriami contained an average of 75% seeds. Green herbage formed 35% of the diet during the winter quarter. Kangaroo rats showed a high preference index for Erodium cicutarium seeds, which were larger and had a higher caloric value than the seeds of other annual plants. The average assimilation efficiency was 0.87 for the natural diet. Estimates indicated that kangaroo rats consumed 97.8 megacal ha—1yr—1, 99% of which was from the primary production. Total net primary production (NPP) on the study area was only 1,400 megacal ha—1yr—1; of this, 900 megacal ha—1yr—1 was considered to be available to D. merriami. Kangaroo rats consumed 6.9% of the NPP. This is higher than for any other rodent populations that have been studied and is probably due to the large proportion of available production (AP) in the total primary production (64%). The population consumed 10.7% of AP, which is high when compared to most other rodent species. The high consumption efficiency for D. merriami may be an adaptation to areas of low production, or it may be simply the result of high densities of kangaroo rats in areas of low production. Dipodomys merriami consumed over 95% of the estimated Erodium production and 90% of the total Erodium production. It is estimated that the rats consumed a sufficient number of Erodium seeds in 1970 to reduce the density of that plant by more than 30% in 1971. The D. merriami population was on the brink of overexploitation of its food sources and was potentially food limited. It is probable that desert herbivores in general are food limited since productivity in the desert is so variable.

On Biomass and Trophic Structure of the Central Amazonian Rain Forest Ecosystem

The importance of litter in the total energy flow dynamics of a central Amazonian rain forest near Manaus, Brazil, is discussed. The study area is located in the hinterland of Manaus between the Rio Negro and the Amazon. Its substrate is Tertiary sediment. The area receives 1771 mm rainfall per year, and the soil is classified as yellow latosol. The forest comprises 93,780 dicotyledonous trees and palms per hectare reaching 38.10 meters in height. Over 500 species of palms and dicotyledonous trees above 1.5 m. in height are identified for a 2000 sq. m. plot. The estimate for fresh living dicotyledonous tree and palm biomass is 939.5 metric tons per hectare consisting of 1.9% leaves, 49.7% stems, 21.3% branches and twigs, and 27.1% roots. Lianas, vascular epiphytes, and parasites are estimated to comprise 46.2 mt/hectare in the fresh state. At the soil surface there are 59 mt/hectare of fresh litter. Living animal biomass is about 200 kg/hectare of which half is soil fauna. The high proportion of soil fauna, the type of humus, the decomposition of litter, the apparent dependence of soil fauna on fungi, and the low nutrient content of litter are all factors which strongly support a consumer food chain based almost entirely on dead organic matter. The fungi play a decisive role in concentrating the otherwise limited nutrient resources. ECOLOGICAL STUDIES carried out in the Amazon region (Fittkau et al. 1969) raised further questions concerning the richness of the Amazonian ecosystems, the distribution of their biomass, and importance of overall as well as trophic-level structure. Additional experience obtained through later fieldwork in Amazonia and the results of our studies in hydrobiology, ecology, landscape ecology, pedology, and terrestrial production indicated the importance of finding out what the relationship of all these factors is in the entire central Amazonian' rain forest where the predominant soil type is latosol. Also considered must be the geochemical structure of that region, the division of the area as demonstrated by Fittkau (1969, 1970a, 1970b, 1971a, 1971b; fig. 1), and its influence on the nutrient supply available to the biomass in terrestrial and aquatic environments. A discussion of the bioenergetics of a tropical rain forest is difficult because few studies have been conducted either on the basis of the specific trophic levels involved or on the basis of the whole biomass. As a consequence, a discussion of available nutrients for specific species at various trophic levels is even more difficult. However, comparisons of litter-fall with the soil complex have been published, and the results are interesting enough to investigate the problem further. In a study by Klinge and Rodrigues (1968), the litter-fall of a central Amazonian tropical lowland rain forest was determined for 1963 and 1964. The average litter-fall for this period shows that 7.3 metric tons (mt) of dry matter per hectare (h) per year are returned to the soil. Dry matter per hectare is made up of 5.6 mt of leaves, or 76.6 percent of the total dry matter; the remainder is composed of flowers, small fruits, and twigs. It is interesting to note that this amount of litter is smaller than the litter-fall reported for tropical rain forests in Africa and Asia (Bray and Gorham 1964). Klinge and Rodrigues (1968) showed hat Amazonian litter is poorer in nutrients when compared with litter from other tropical forests. Results from our chemical analyses indicated that the following raw elements occur in the litter returned to the soil in central Amazonia (kg per hectare per year): 2.2 P, 12.7 K, 5.0 Na, 18.4 Ca, 12.6 Mg, and 105.6 N. In 1970, estimates were made of the amount of woody material involved in litter-fall of the central Amazonian rain forest (Klinge, unpublished). The results of the analyses show that one mt of stems (stem-part of plant between soil surface and first ramification), two mt of branches (ramifications without leaves), and 1.35 mt of twigs (ramifications bearing leaves), bark, etc. are involved. Because the 1963-1964 litter-fall experiment was not suitable for the measurement of the total fruit-fall, we calculated roughly the amount of fruits involved in annual litter-fall by kind, weight, and number of fruits in a 2000 m2 forest plot. Thus, we determined amounts of 0.35 mt of small fruits (up to 5 g in weight) and 0.5-1.0 mt of larger fruits (over approximately 5 g in weight). We 1 In this paper, 'central Amazonia' and 'central Amazonian' refer only to the ecological unit of Amazonia defined by Fittkau (1963) and illustrated in figure 1. 2 BIOTROPICA 5(1): 2-14 1973 This content downloaded from 157.55.39.243 on Wed, 05 Oct 2016 04:36:47 UTC All use subject to http://about.jstor.org/terms

Annual Energy Expenditure by the Avifauna of a Northern Hardwoods Ecosystem

The avian standing crop of the Hubbard Brook northern hardwoods watershed. ecosystem in central New Hampshire (USA) was determined during two years. The numbers and biomass vary seasonally, with peak abundances averaging 325 individuals of 25-26 species/10 ha and 6535 g/10 ha in early July and lows of 22 individuals of 6 species/10 ha and 441 g/10 ha during the long cold winters. Combining these data on standing crop with estimates of respiratory metabolism derived from laboratory studies gives an estimate of avian respiratory metabolism in the Hubbard Brook forest of 5 kcal m-2 yr-1. Avian production is calculated at 0.06 kcal m-2 yr-1. Since 80 per cent of the annual diet of the avifauna is considered to be at the secondary consumer level, the total energy flow estimate for secondary consuming birds is 4.04 kcal m-2 yr-1. This represents 0.1 per cent of the net primary production in the forest ecosystem, a figure which fits closely with values predicted from the literature.

Energy and Nutrient Dynamics of Spider and Orthopteran Populations in a Grassland Ecosystem

Population dynamics, energy budgets, and nutrient concentrations were used to develop a compartment model for evaluating energy flow and nutrient fluxes in the spider and orthopteran components of an eastern Tennessee grassland ecosystem. The arthropod community consisted of; herbivores–Melanoplus sanguinipes (Acrididae), Conocephalus fasciatus (Tettigoniidae), and several of the Homoptera—Hemiptera; omnivore–Pteronemobius fasciatus (Gryllidae); and predators–Lycosa spp. (Lycosidae). Weekly estimates of arthropod density and biomass and monthly estimates of vegetation biomass were made during the 1965—69 growing season. Supporting studies included: (1) determination of caloric equivalents; (2) measurements of arthropod metabolism; (3) determination of whole—body concentrations of Na, Ca, and K; (4) estimation of biological turnover rates of these nutrients with radioactive analogues; and (5) field studies of arthropod feeding habits and food consumption. Total net primary production of the grassland ecosystem was 1,274 kcal/m2; 89% of this total was by grass species (Festuca arundinacea and Andropogon virginicus) and 11% by green forbs. Herbivores and omnivores consumed 9.6% (122.9 kcal/m2) of net primary production. Annual net secondary production by the insect community was 32.05 kcal/m2. Total net tertiary production by spiders was 2.26 kcal/m2. Total annual energy flow (= total assimilation) through the community was 75.6 kcal/m2. Herbivores accounted for 79.8% of this total, omnivores 12.2%, and predators 8.1%. Whole—body concentrations of sodium increased with higher trophic position in the food chain: vegetation (0.43 mg/g ash free dry wt = AFDW), prey (1.18 mg/g AFDW), and predators (1.94 mg/g AFDW). Calcium concentrations decreased from vegetation (5.82 mg/g AFDW) to prey (0.85 mg/g AFDW) and remained constant to predators (0.88 mg/g AFDW). Potassium concentrations were much higher in vegetation (14.28 mg/g AFDW) than in either the prey (1.87 mg/g AFDW) or predators (1.96 mg/g AFDW), which were essentially the same. Sodium and potassium behaved similarly in their movement through arthropod food chains. The low concentrations of calcium in arthropod trophic levels and the rapid elimination of this element from each trophic level suggest that calcium is not as limiting as are sodium and potassium in this arthropod community. Herbivores, the dominant members of the arthropod fauna, attained a maximum standing crop of 927 mg/m2 (Melanoplus = 705 mg/m2, Conocephalus = 200 mg/m2, and the Homoptera—Hemiptera = 22 mg/m2). This trophic level was responsible for 85% of the sodium turnover, 76% of the calcium turnover, and 78% of the potassium turnover by the arthropod component of the ecosystem. The omnivore Pteronemobius fed equally well on fresh vegetation and on litter. It reached a maximum biomass of 194 mg/m2 and utilized 10% of the sodium, 22% of the calcium, and 20% of the potassium which passed through the arthropod community. The predator (Lycosa spp.) biomass reached a maximum of 146 mg/m2 in late fall and was responsible for 5% of the sodium, 2% of the calcium, and 2% of the potassium utilized by the arthropod component of the ecosystem. Wolf spiders consumed 21% of total net secondary production. Absence of other predator species in collections from the arthropod community suggests that Lycosa was the dominant invertebrate predator in this grassland ecosystem.

A Vacuum Tube Compensated Flat Top High-Current Pulse Supply for Symmetrical Torus Machine

The conversion of the Model C Stellarator to a symmetrical torus machine produced a longer plasma confinement time. This, In turn, required a longer ohmic heating current pulse than could be supplied by the existing vacuum tube system controlling the total energy flow. A new energy supply, consisting of a high-voltage capacitor bank and crowbar coupled with a low-voltage pulse-forming network of electrolytic capacitors, has been added In parallel with the existing vacuum tube system such that the two are complementary. The composite supply is capable of producing longer pulses with a greater amplitude and, at the same time, permits modulation of the flat top.

Alkyl benzene sulfonate effects on stream algae communities

ABS is toxic to fish and other aquatic organisms. It also is toxic at varying concentrations to lower life forms at all trophic levels within the aquatic environment. Algae represents the level of the primary producer. Those forms ranking above it are dependent upon it for their energy supply. A reduction in the productive ability of algal communities will result in a reduction of the total energy flow and a consequent reduction in the productive capacity of the entire community. The object of this investigation was to determine the effects of alkyl benzene sodium sulfonate on the productivity of stream algal communities.

Heat transfer and reaction in laminar tube flow

AbstractAn analytical study was made of the temperature and composition distribution and heat transfer characteristics for a reacting fluid in a tube. The reaction was assumed to be first order and irreversible and the flow to be laminar.The results, which consisted of radial and axial profiles of temperature, composition, and Nusselt number could be expressed in terms of four parameters. The gradient of radial composition was usually sufficient to judge the effect of reaction on the heat transfer coefficient. Owing to residence time and temperature effects, the Nusselt number even for an exothermic reaction was usually greater than that for an inert system. For endothermic cases, the energy flux due to diffusion increases the total energy flow, and the Nusselt number may be several fold that in the corresponding nonreactive system.For certain values of the parameters the radial temperature and composition profiles showed maxima and minima between the wall and center of the tube. At these conditions the direction of the flow of energy due to diffusion could not explain the increase in Nusselt number.

Bioenergetics of the Southern Harvester Ant, Pogonomyrmex Badius

The bioenergetics of the southern harvester ant were studied on the Savannah River Project, Aiken, South Carolina. Excavation of hills revealed that density of ants ranged from 4,000 to 6,000 per hill. Labeling ants with P32 indicated that only 10% of the ants in a colony were active above ground during any 2—week period (the limit of recognition of the label); thus, short—term marking recapture estimates based on above—ground individuals greatly underestimate the size of the colony. There were 27 hills per hectare on the study area. The consumption of oxygen of workers at various temperatures was determined in a simple respirometer, and the temperature at which the ants were living in the field was determined during a year's observation at mounds. The energy expense of heat production was calculated from the oxygen consumption and activity temperature records. Total energy flow (heat production plus tissue growth) was highest in summer and lowest in winter. The annual range was from 14 to 48 kgcal/m2/yr. Tissue growth was estimated to amount to only 0.09 kgcal/m2/yr. Energy flow in this species was higher than that of 2 vertebrate granivores studies in the same field, the old—field mouse and the savannah sparrow.

Use of focused antenna for ionized trail measurements: Part I. Power transfer between two focused antennas

The transmission efficiency for power transmission between two identical circular apertures is considered. Each aperture is focused in a common focal plane which is located midway between them. The transmission efficiency is evaluated in terms of the percentage of the total energy flow through the focal plane which flows through a circular area of arbitrary radius, centered at the focal point and coincident with the focal plane. The results are used to estimate the diffraction error (leakage of energy around the phenomena to be observed) that arises when the focused beam system is used to probe a cylindrical ionized column in the focal plane. Kirchoff theory is used throughout, and perturbation of the focal field distribution due to the presence of the plasma is neglected. The effect of this perturbation has been analyzed theoretically and will be the subject of future papers.