Investigation of optimization of attitude control systems, volume i
Optimization of attitude control systems by development of mathematical model and computer program for space vehicle simulation
SPACE VEHICLE↗
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Results for “Mathematical Model”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Identification Approach to Alleviate Effects of Unmeasured Heat Gains for MIMO Building Thermal Systems
It is important to have practical methods for constructing a good mathematical model for a building's thermal system for energy audits, retrofit analysis and advanced building controls, e.g. model predictive control. Identification approaches based on semi-physical model structures are popular in building science for those purposes. However conventional gray box identification approaches applied to thermal networks would fail when significant unmeasured heat gains present in estimation data. Although this situation is very common and practical, there has been little research to tackle this issue in building science. This paper presents an overall identification approach to alleviate influences of unmeasured disturbances, and hence to obtain improved gray-box building models. The approach was applied to an existing open space building and the performance is demonstrated.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Optimizing Labor Resources at Manufacturing Enterprises
Attention focuses on the selection of mathematical models and the formulation of algorithms for organizational decision making in optimizing labor resources at manufacturing enterprises. Examples of labor optimization are presented.
42 ENGINEERING↗
Study of Plume Eye in the Copper Bottom Blown Smelting Furnace
In the present study, the plume eye, which is a gas bubble plume generated by pushing away the upper layer liquid having a lower density and the exposure of the lower layer liquid which has a relatively higher density, was studied systematically in a bottom blown furnace model. A series of single lance experiments were carried out in a horizontal cylindrical furnace model to evaluate the effects of gas flowrate, lower layer thickness and upper layer thickness on the size of plume eye. The corresponding eye areas under different experimental conditions were measured. The results suggest that the eye size increases with increase of the gas flowrate and lower layer thickness. On the other hand, the eye size is reduced with increasing upper layer thickness. A mathematical model has been developed to predict the eye area in a horizontal cylindrical furnace by a single bottom blown lance.
36 MATERIALS SCIENCE↗
Dynamic Model of Basic Oxygen Steelmaking Process Based on Multi-zone Reaction Kinetics: Model Derivation and Validation
A multi-zone kinetic model coupled with a dynamic slag generation model was developed for the simulation of hot metal and slag composition during the basic oxygen furnace (BOF) operation. The three reaction zones (i) jet impact zone, (ii) slag–bulk metal zone, (iii) slag–metal–gas emulsion zone were considered for the calculation of overall refining kinetics. In the rate equations, the transient rate parameters were mathematically described as a function of process variables. A micro and macroscopic rate calculation methodology (micro-kinetics and macro-kinetics) were developed to estimate the total refining contributed by the recirculating metal droplets through the slag–metal emulsion zone. The micro-kinetics involves developing the rate equation for individual droplets in the emulsion. The mathematical models for the size distribution of initial droplets, kinetics of simultaneous refining of elements, the residence time in the emulsion, and dynamic interfacial area change were established in the micro-kinetic model. In the macro-kinetics calculation, a droplet generation model was employed and the total amount of refining by emulsion was calculated by summing the refining from the entire population of returning droplets. A dynamic Fe{sub t}O generation model based on oxygen mass balance was developed and coupled with the multi-zone kinetic model. The effect of post-combustion on the evolution of slag and metal composition was investigated. The model was applied to a 200-ton top blowing converter and the simulated value of metal and slag was found to be in good agreement with the measured data. The post-combustion ratio was found to be an important factor in controlling Fe{sub t}O content in the slag and the kinetics of Mn and P in a BOF process.
36 MATERIALS SCIENCE↗
Modeling HIV-1 Within-Host Dynamics After Passive Infusion of the Broadly Neutralizing Antibody VRC01
VRC01 is a broadly neutralizing antibody that targets the CD4 binding site of HIV-1 gp120. Passive administration of VRC01 in humans has assessed the safety and the effect on plasma viremia of this monoclonal antibody (mAb) in a phase 1 clinical trial. After VRC01 infusion, the plasma viral load in most of the participants was reduced but had particular dynamics not observed during antiretroviral therapy. In this paper, we introduce different mathematical models to explain the observed dynamics and fit them to the plasma viral load data. Based on the fitting results we argue that a model containing reversible Ab binding to virions and clearance of virus-VRC01 complexes by a two-step process that includes (1) saturable capture followed by (2) internalization/degradation by phagocytes, best explains the data. This model predicts that VRC01 may enhance the clearance of Ab-virus complexes, explaining the initial viral decay observed immediately after antibody infusion in some participants. Because Ab-virus complexes are assumed to be unable to infect cells, i.e., contain neutralized virus, the model predicts a longer-term viral decay consistent with that observed in the VRC01 treated participants. By assuming a homogeneous viral population sensitive to VRC01, the model provides good fits to all of the participant data. However, the fits are improved by assuming that there were two populations of virus, one more susceptible to antibody-mediated neutralization than the other.
60 APPLIED LIFE SCIENCES↗
On a problem of reconstruction of a discontinuous function by its Radon transform
A problem of reconstruction of a discontinuous function by its Radon transform is considered. One of the approaches to the numerical solution for the problem consists in the next sequential steps: a visualization of a set of breaking points; an identification of this set; a determination of jump values; an elimination of discontinuities. We consider three of listed problems except the problem of jump values. The problems are investigated by mathematical modeling using numerical experiments. The results of simulation are satisfactory and allow to hope for the further development of the approach.
97 MATHEMATICS AND COMPUTING↗
A multiscale model of the action of a capsid assembly modulator for the treatment of chronic hepatitis B
Chronic hepatitis B virus (HBV) infection is strongly associated with increased risk of liver cancer and cirrhosis. While existing treatments effectively inhibit the HBV life cycle, viral rebound frequently occurs following treatment interruption. Consequently, functional cure rates of chronic HBV infection remain low and there is increased interest in a novel treatment modality, capsid assembly modulators (CAMs). Here, we develop a multiscale mathematical model of CAM treatment in chronic HBV infection. By fitting the model to participant data from a phase I trial of the first-generation CAM vebicorvir, we estimate the drug’s dose-dependent effectiveness and identify the physiological mechanisms that drive the observed biphasic decline in HBV DNA and RNA, and mechanistic differences between HBeAg-positive and negative infection. Finally, we demonstrate analytically and numerically that the relative change of HBV RNA more accurately reflects the antiviral effectiveness of a CAM than the relative change in HBV DNA.
59 BASIC BIOLOGICAL SCIENCES↗
Selected Problems of the Mechanics of Coupled Fields
We present a brief survey of investigations carried out in recent years by the Lviv scientific school of the mechanics of coupled fields on the problems of construction and generalization of mathematical models and methods aimed at the description, determination, and optimization of the thermomechanical behavior of bodies under the combined action of force, thermal, and electromagnetic loads.
42 ENGINEERING↗
Shaping of the axial power density distribution in the core to minimize the vapor volume fraction at the outlet of the VVER-1200 fuel assemblies
The possibility of decreasing the vapor fraction at the VVER-1200 fuel assembly outlet by shaping the axial power density field is considered. The power density field was shaped by axial redistribution of the concentration of the burnable gadolinium poison in the Gd-containing fuel rods. The mathematical modeling of the VVER-1200 core was performed using the NOSTRA computer code.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
First compilation of papers on trajectory analysis and guidance theory
Mathematical models to approximate functions, bounds and power series for three-body problems, satellite orbit theories, and other aspects of trajectory analysis and guidance theory
POWER SERIES↗
Study of a Single-Power Two-Circuit ESR Process with Current-Carrying Mold: Mathematical Simulation of the Process and Experimental Verification
A novel single-power two-circuit ESR process (ESR-STCCM) with current-carrying mold has been investigated via numerical simulation and experimental research in this paper. A 2D quasi-steady-state mathematical model is developed to describe ESR-STCCM. The electromagnetic field, flow field, slag pool temperature distribution, and the shape of a molten steel pool in ESR-STCCM have been investigated by FLUENT software as well as user-defined functions (UDF). The results indicate that ESR-STCCM is different from the conventional ESR process. The maximum electromagnetic force, current density, Joule heat, and slag pool flow velocity are located in the lower part of the conductor in the ESR-STCCM process. The direction of the maximum electromagnetic force inclines upward. There are two distinct vortices in the slag pool. The larger swirl rotates counterclockwise near the conductor, with a value of 0.0263 m s{sup −1} due to the interaction of the electromagnetic force and gravity. The maximum temperature of the slag pool is 2070 K (1797 °C) and is located in the center of the swirl with a filling ratio of 0.6 and a 20 mm electrode immersion depth. The depth of a molten steel pool is shallower, which is conducive to improving solidification quality. In addition, the filling ratio of 0.6 is conducive to controlling steel solidification quality. Some experiments have been done, and the numerical model is confirmed by experimental results.
36 MATERIALS SCIENCE↗
Selection of Working Frequencies in Complex Plane Motion of Saws within a Woodcutting System
Abstract—A woodcutting system based on complex plane motion (translation + rotation) of the saw blades is promising in principle but proves unstable in practice. This may be addressed by selecting working frequencies of the saws that differ from the eigenfrequencies and other parametric frequencies of the system. To that end, those frequencies must be identified. In the present work, a mathematical model of the saw system is derived. Its mass and size are optimized. On that basis, an energy-saving sawing machine superior in performance to comparable machines is manufactured and tested.
42 ENGINEERING↗
Developing the Oxidation Kinetic Model for Magnetite Pellet
Oxidation is a vital phenomenon for magnetite pellets in their excursion through the furnace during induration. One of the pre-requisites for magnetite pellets to achieve homogeneously structured good quality pellets is to have complete oxidation before sintering begins. Partially oxidized magnetite pellets, upon sintering, might result in inhomogeneous structured pellets which could be detrimental to pellet quality. It is necessary to understand the mechanisms responsible for magnetite oxidation, and hence, it is intended in this study to investigate experimentally as well as develop a mathematical model based on oxidation kinetics. Oxidation of pellets is largely influenced by the oxidation kinetics of particles and hence should be studied at particle as well as at pellet scale. The principles of the Grain Model have been adopted to develop the Oxidation Model at pellet scale, whereas the particles’ oxidation follows the Avrami Kinetic Model. Isothermal oxidation experiments performed Thermogravimetric Analyzer showed that oxidation rate of magnetite at pellet scale contained two peaks. They were complemented well by oxidation rates predicted from the model. Further, the pellet was investigated microstructurally at pellet and particle scale to substantiate the findings from the experiments and the model. The oxidation model developed is used to predict the progression of oxidation in the magnetite pellet with respect to the reaction time at three different temperatures (873 K, 973 K, and 1073 K (600 °C, 700 °C, and 800 °C)) and at four levels of oxygen (0.21, 0.30, 0.60, and 1.00 atm) in the oxidizing gas.
36 MATERIALS SCIENCE↗
Effect of Slag Composition on the Crystallization Kinetics of Synthetic CaO-SiO{sub 2}-Al{sub 2}O{sub 3}-MgO Slags
The crystallization kinetics of CaO-SiO{sub 2}-Al{sub 2}O{sub 3}-MgO (CSAM) slags was studied with the aid of single hot thermocouple technique (SHTT). Kinetic parameters such as the Avrami exponent (n), rate coefficient (K), and effective activation energy of crystallization (E{sub A}) were obtained by kinetic analysis of data obtained from in situ observation of glassy to crystalline transformation and image analysis. Also, the dependence of nucleation and growth rates of crystalline phases were quantified as a function of time, temperature, and slag basicity. Together with the observations of crystallization front, they facilitated establishing the dominant mechanisms of crystallization. In an attempt to predict crystallization rate under non-isothermal conditions, a mathematical model was developed that employs the rate data of isothermal transformation. The model was validated by reproducing an experimental continuous cooling transformation diagram purely from isothermal data.
36 MATERIALS SCIENCE↗
Adaptive finite state models of the human operator
Human operator adaptive finite state mathematical models
Angel, E. S.↗
Random independent splitting model for the mass spectrum of protostars and interstellar clouds
Mathematical model for mass spectra of protostars and interstellar clouds
Marcus, A. H.↗
Gravity model comparison using GEOS-1 long arc orbital solutions
Gravity mathematical models compared and verified using Explorer 29 /GEOS 1/ long arc orbital solutions
Lerch, F. J.↗