Showing papers by "University of Florida published in 1970"
TL;DR: In this article, the authors question seriously the basis for this practice and prove by the methods of optimum control that better response and wider stability margins can be obtained by lower bias settings.
Abstract: The North American Power Systems Interconnection Committee recommends that each control area set its frequency bias equal to the so-called area frequency response characteristic (AFRC). The authors question seriously the basis for this practice and prove by the methods of optimum control that better response and wider stability margins can be obtained by lower bias settings.
746 citations
TL;DR: This paper records the development of a state variable model of the megawatt-frequency control problem of multiarea electric energy systems in a mathematical form necessary for application of theorems of modem optimal control theory.
Abstract: This paper records the development of a state variable model of the megawatt-frequency control problem of multiarea electric energy systems. The model is in a mathematical form necessary for application of theorems of modem optimal control theory.
668 citations
TL;DR: In this article, the authors discuss three orthonormalization procedures, such as successive, symmetric, and canonical orthonormization, for a finite set of functions, in which each member of the set in order is orthogonalized against all the previous members and subsequently normalized.
Abstract: Publisher Summary This chapter discusses three orthonormalization procedures, such as successive orthonormalization, symmetric orthonormalization, and canonical orthonormalization The simplest way of orthonormalizing a finite set of functions is by the classical Schmidt procedure, in which each member of the set in order is orthogonalized against all the previous members and subsequently normalized In solid-state theory, one could probably construct orthonormal combinations of the atomic orbitals of the system, which would still preserve the natural symmetry In such an approach, it would be necessary to treat the given functions ϕ = {ϕ 1 , ϕ 2 …, ϕ n } simultaneously, on an equivalent basis instead of successively as in the Schmidt procedure In molecular and solid-state theory, there are cases when also the symmetric orthonormalization procedure will break down, depending on the fact that, even if the basis ϕ = {ϕ 1 , ϕ 2 …, ϕ n } is linearly independent from the mathematical point of view, it may be approximately linearly dependent from the computational point of view This phenomenon causes a great many complications and may lead to very misleading results, since the associated secular equations may be almost identically vanishing Unfortunately, it seems as if many of the conventionally used basic systems are strongly affected by approximate linear dependencies In order to systematize this problem, it is convenient to study the metric matrix
662 citations
TL;DR: In this paper, a variational method for efficiently calculating energy bands and charge densities in solids is presented; the method can be viewed as a weighted local energy procedure or alternately as a numerical integration scheme.
Abstract: A general variational method for efficiently calculating energy bands and charge densities in solids is presented; the method can be viewed as a weighted local-energy procedure or alternately as a numerical integration scheme. This rapidly convergent procedure circumvents many of the difficulties associated with the evaluation of matrix elements of the Hamiltonian in an arbitrary basis and treats the general nonspherical potential with no more complication than the usual "muffin-tin" approximation. Thus the band structure of ionic and covalent materials can be calculated with realistic crystal potentials. As an example, the method is applied to the one-electron model Hamiltonian with a nonspherical local potential, using a linear combination of atomic orbitals basis. Matrix elements of the Hamiltonian are evaluated directly without decomposition into atomic basis integrals; no "tight-binding" approximations are made. Detailed calculations are presented for the band structure and charge density of bcc lithium which demonstrate the feasibility of our method, and reveal the sensitivity of the energy bands to nonspherical and exchange components of the crystal potential. Various prescriptions for the construction of crystal potentials are considered, and convenient least-squares expansions are described. The extension of these methods to nonlocal potentials such as are encountered in the Hartree-Fock self-consistent-field procedure is discussed.
614 citations
TL;DR: It was concluded that pulse wave characteristics, particularly dp/dtmax, are important in the propagation of dissection.
Abstract: It has been argued that pulse wave characteristics are important factors in extension and rupture of acute dissecting aneurysms. To test this, a standard model of an aorta was constructed, consisting of an outer layer of Tygon tubing and an inner layer of rubber cement. An "intimal tear" was produced and the "aorta" was subjected to nonpulsatile and pulsatile flow with increasing increments of pressure.
With nonpulsatile flow alone (97 experiments) no dissection occurred at pressures up to 400 mm Hg. Pulsatile flow produced rapid and usually complete dissection with a maximum systolic pressure of 120 mm Hg.
The extent of dissection per pulse was related to dp/dtmax in the fluid. No dissection occurred until a critical value of dp/dtmax (790 mm Hg/sec) was reached. Dog aortas were then used in place of the Tygon tube "aorta" with similar results; i.e., dissection did not occur with nonpulsatile flow, but did occur with pulsatile flow (3800 mm Hg/sec). The dissecting dog aorta ruptured to the outside or reentered the vessel lumen.
It was concluded that pulse wave characteristics, particularly dp/dtmax, are important in the propagation of dissection.
365 citations
TL;DR: In this article, the static cone-bearing capacity and sand compressibility were measured by a special screw-plate form of plate-bearing load test, and a single distribution of a strain influence factor was assumed for all cases.
Abstract: At least two methods for using static cone data to predict settlement exist and have received extensive use—those of Terzaghi-Peck-Meyerhof and Buisman-DeBeer. Another method is presented in this paper. All three methods are then applied to 16 test cases involving either actual foundations, or plate load tests, with measured settlements. The proposed method simplifies calculations without sacrificing conservatism, yet appears most accurate over the full scope of the available test cases. These involve foundation widths of 2 ft to 184 ft. The key feature of the new method is that a single distribution of a strain influence factor is assumed for all cases. This method eliminates the need to compute the intermediate parameter of change in vertical stress with depth below a shallow footing. Also presented is a new correlation between static cone-bearing capacity and sand compressibility. Compressibility was measured in-situ by a special screw-plate form of plate-bearing load test. New data are included for the correlation between the static cone-bearing capacity and SPT blow count values in sands.
287 citations
01 Jun 1970
TL;DR: In this article, the formation of new nickel oxide upon boundaries of columnar grains where nickel diffusing through the oxide crystals, meets oxygen, diffusing along grain boundaries is identified as the primary cause of this stress.
Abstract: The oxidation of nickel near 1000°C is accompanied by the generation of stresses parallel with the metal-oxide interface and of magnitude (~1500 psi) sufficient to elongate nickel rod, increase sheet area, and sharpen the angle of bend of ells and helices. A primary cause of this stress is identified with the formation of layers of new nickel oxide upon boundaries of columnar grains where nickel, diffusing through the oxide crystals, meets oxygen, diffusing along grain boundaries. Classical parabolic growth of the scale gives way to a slower quasilinear rate when the major site of new oxide formation is abruptly shifted to a system of grain boundaries lying close to the metal surface and created by recrystallization of the oxide under the influence of stress and high temperature. Another source of stress in the scale arises from the constantly changing area of the metal-oxide interface when oxidation is occurring upon curved metal surfaces. This stress reinforces that generated by deposition of material at oxide grain boundaries when the surface is convex and opposes it when the surface is concave.
251 citations
204 citations
TL;DR: The interactions of basal rate of metabolism, thermal conductance, body temperature, lower limit of thermoneutrality, and body weight in mammals are compatible with Newton's law of cooling.
Abstract: 1. The interactions of basal rate of metabolism, thermal conductance, body temperature, lower limit of thermoneutrality, and body weight in mammals are compatible with Newton9s law of cooling. 2. A small body weight will normally reduce the level and preciseness of body temperature, but a high basal rate of metabolism or a low thermal conductance may compensate for a small size and permit a high, precise temperature to be maintained. 3. The parameters of energetics that fix the level and preciseness of body temperature in mammals are ultimately correlated in turn with the environmental parameters of climate and food habits. 4. Birds generally have higher temperatures than mammals because the basal rates of metabolism are higher and the conductances lower in birds than in mammals of the same weight.
161 citations
TL;DR: In this paper, the media and culture conditions required for in vitro stimulation of mouse lymphoid cells are described and the possible role of the mouse cell agglutinin (AMLG) is discussed.
Abstract: The media and culture conditions required for in vitro stimulation of mouse lymphoid cells are described. The medium was arginine-rich and contained heat-inactivated human serum. A component of the human sera necessary for stimulation of the cells was a natural mouse cell agglutinin, which affected both background stimulation and the degree of induced stimulation with phytohemagglutinin (PHA). Absorption of the agglutinin from the human serum rendered the medium incapable of sustaining DNA synthesis in the presence of PHA.
The response to PHA of mouse spleen and thymus cells was age-dependent and, although this response was not present at birth, it rapidly rose to adult levels. Spleen cells from mice immunized with bacillus Calmette-Guerin (BCG) or sheep erythrocytes (SRBC) showed increased in vitro reactivity to added purified protein derivative (PPD) or SRBC stroma, dependent on the time of immunization.
The dose response curve for the SRBC stroma stimulated, immune spleen cells is compatible with a theory of cell to cell interaction being necessary for an in vitro reaction to antigen.
The possible role of the mouse cell agglutinin (AMLG) is discussed.
151 citations
TL;DR: The metabolic cost of swimming was studied in mallard ducks which had been trained to swim steadily in a variable-speed water channel and indicated a maximum overall efficiency for the swimming ducks of about 5%, whereas Ships typically have maximum efficiencies of 20-30%.
Abstract: 1. The metabolic cost of swimming was studied in mallard ducks ( Anas platyrhynchos ) which had been trained to swim steadily in a variable-speed water channel. 2. At speeds of from 0.35 to 0.50 m/sec the oxygen consumption remained relatively constant at approximately 2.2 times the resting level. At speeds of 0.55 m/sec and higher the oxygen consumption increased rapidly and reached 4.1 times resting at the maximum sustainable speed of 0.70 m/sec. 3. The maximum sustainable swimming speed of the ducks coincided with the limit predicted from hydrodynamic considerations of the water resistance of a displacement-hulled ship of the same hull length as a duck (0.33 m). 4. The cost of transport (metabolic rate/speed) reached a minimum of 5.77 kcal/kg km at a swimming speed of 0.50 m/sec. Ducks swimming freely on a pond were observed to swim at the speed calculated in experimental trials to give minimum cost of transport. 5. Drag measurements made with model ducks indicated a maximum overall efficiency (power output/power input) for the swimming ducks of about 5%. Ships typically have maximum efficiencies of 20-30%. Because of the difficulty in delimiting the cost of swimming activity alone from the other bodily functions of the duck, overall efficiency may present an incorrect description of the swimming performance of the duck relative to that of a ship. An hydrodynamic parameter such as speed/length ratio [speed/(hull length)½] whereby a duck excels conventional ships may present a more appropriate comparison.
TL;DR: The effect of ouabain on cochlear potentials and endolymph composition was studied in guinea pigs, and lowering the concentration of sodium in the perilymph minimized the action of oUabain.
Abstract: The effect of ouabain on cochlear potentials and endolymph composition was studied in guinea pigs. Introduction of ouabain into the perilymphatic space resulted in a serious depression of cochlear ...
TL;DR: Results of these studies indicate that the proteinase and peptidase inhibitor, Trasylol, is not required for inclusion in this radioimmunoassay method for measurement of gastrin, and under the conditions of elevated temperature utilized in these studies immunoreactivity of Gastrin was found to be thermostable.
TL;DR: In this article, a tractable, relativistic theory for the two-nucleon system is constructed and an instantaneous-interaction approximation to the Bethe-Salpeter (BS) equation is derived.
Abstract: A tractable, relativistic theory for the two-nucleon system is constructed. As a starting point, the Bethe-Salpeter (BS) equation is utilized. In order to reduce the BS equation to three dimensions, the Blankenbecler-Sugar method is generalized to include spin-\textonehalf{} particles. An instantaneous-interaction approximation to the BS equation is also investigated, and results similar to those obtained with the Blankenbecler-Sugar method are derived. Finally, as an application, the generalized potential or interaction kernel is approximated to order ${g}^{2}$ and compared to the one-pion-exchange potential (OPEP) used in conjunction with the Schr\"odinger equation. The singlet states are treated numerically, and results are presented which show that for a lab kinetic energy of 400 MeV, the phase shifts calculated from the relativistic theory differ from those calculated by solving the Lippmann-Schwinger or Schr\"odinger equation with OPEP by about 20%.
TL;DR: The possibility of different sleep stage characteristics being associated with different sleep lengths was explored by comparing two groups of high school seniors, who characteristically slept 6� hours or less or who slept 8.� hours or more, with an age-matched control group not selected on the basis of sleep length.
Abstract: The possibility of different sleep stage characteristics being associated with different sleep lengths was explored by comparing two groups of high school seniors, who characteristically slept 6(1/2) hours or less or who slept 8(1/2) hours or more, with an age-matched control group not selected on the basis of sleep length. All-night electroencephalography was used to examine the sleep stage characteristics of these groups. Compared with the unselected age-matched group, the short sleepers showed no significant diminution in their stage 4 (deep) or rapid eye movement (dream) sleep. The long sleepers were observed to obtain significantly more rapid eye movement sleep than did the other groups.
TL;DR: The results indicated that septal ablation increased the aggressiveness of both socially naive and experienced dominant hamsters, with high levels of aggression between paired animals.
TL;DR: The development and application of an electronic system which is capable of automatically detecting the K-complexes, aperiodic waveforms found in sleep electroencephalograms, is described.
Abstract: The development and application of an electronic system which is capable of automatically detecting the K-complexes, aperiodic waveforms found in sleep electroencephalograms, is described. The system can be used either on- or off-line.
TL;DR: It was speculated that these increasing fasting serum gastrin levels with increasing age may reflect the effects of achlorhydria (and less complete forms of reduced acid secretion) in removing the usual inhibition of gastrin release due to antral acidification.
Journal Article•
TL;DR: Easurement of the time rate of change of fluorescein concentration in the various ocular tissues permits the in vivo study of various parameters of ocular physiology.
Abstract: M. -easurement of the time rate of change of fluorescein concentration in the various ocular tissues permits the in vivo study of various parameters of ocular physiology. Tear flow, epithelial and endothelial permeability, and drug penetration into the anterior segment are some of the parameters that can be evaluated. These studies can be performed only if an accurate, reliable, slit lamp fluorophotom-
TL;DR: Changes in the amount and kind of social behavior were observed in male hamsters following amygdalectomy and both preoperatively dominant and submissive animals retained their social status after surgery.
TL;DR: The latter term is introduced to indicate that in many patients with asplenia or polysplenia syndrome, the visceral situs cannot be determined because of symmetrical development of normally asymmetrical organs.
Abstract: To arrive at an accurate anatomic diagnosis in patients with complex cardiovascular malformations or abnormal position of the heart, the situs of the viscera, or more specifically, that of the atria, must be known. Since the situs of the atria always corresponds to that of the tracheobronchial tree, the latter is a very reliable indicator of visceral (atrial) situs. A chest roentgenogram taken in the anteroposterior or posteroanterior projection will show the anatomy of the air-filled trachea and main bronchi, thus indicating whether there is situs solitus, situs inversus or “situs ambiguus”. The latter term is introduced to indicate that in many patients with asplenia or polysplenia syndrome, the visceral situs cannot be determined because of symmetrical development of normally asymmetrical organs.
TL;DR: Gestation is associated with a decrease in albumin concentration, no significant variation in concentrations of the three major classes of immunoglobulins and of α 2 -macroglobulin, and with an increase in the concentration of transferrin, ceruloplasmin, and α 1 -antitrypsin.
TL;DR: The research emphasizes the existence of a relationship between cell differentiation and morphogenesis and suggests that mature spore differentiation depends upon an interaction with differentiating prestalk cells during culmination.
TL;DR: It was concluded that alcohol consumption per se and not a nutritional deficiency was responsible for the impairment of learning.
Abstract: Chronic alcohol consumption impaired the learning of a two-way shuttle box avoidance task in mice 10 to 14 days after the discontinuation of ethanol in the diet. Control groups received laboratory chow ad libitum or were pair-fed with the alcohol-consuming mice by diets containing isocaloric amounts of sucrose. The performance of the two control groups was indistinguishable from each other, and only the ethanol-consuming mice performed poorly. It was therefore concluded that alcohol consumption per se and not a nutritional deficiency was responsible for the impairment of learning.
Journal Article•
TL;DR: Bionite lenses, either untreated or pretreated with fluorescein, markedly increase the concentration of this drug in the anterior segment of the eye, suggesting that these lenses may be useful adjuncts in attaining and maintaining high drug concentrations in the eye without the use of frequent topical medication.
Abstract: Hydrophilic contact lenses take up and release fluorescein from solution in a measurable manner. This is more rapid with Bionite than with the Soflens lenses. Bionite lenses, either untreated or pretreated with fluorescein, markedly increase the concentration of this drug in the anterior segment of the eye. This suggests that these lenses may be useful adjuncts in attaining and maintaining high drug concentrations in the eye without the use of frequent topical medication. The drug concentration attained with these lenses is higher than that possible with frequent topical medication alone.
TL;DR: Proteinuria and œdema appeared to be exacerbated in all four cases with increased exposure to inhalant allergens, and in the pollen-sensitive patients the proteinuria appeared to subside while they were being treated with hyposensitisation injections.
TL;DR: In this paper, the electrochemical behavior of gold was investigated in 0.1 M HClO4 containing 2−100×10−4 M of KCl or KBr, using triangular sweep voltammetry, steady-state current potential measurements and single pulse differential capacity data.