scholarly journals Scale Effects on Quasi-Steady Solid Rocket Internal Ballistic Behaviour

2021 ◽  
Author(s):  
David R. Greatrix
Keyword(s):  
Scale Effects ◽  
The Other ◽  
Simulation Program ◽  
Erosive Burning ◽  
Internal Ballistics ◽  
Minor Influence ◽  
Solid Rocket ◽  
Experimental Firing ◽  
A Minor ◽  
Component Models

The ability to predict with some accuracy a given solid rocket motor’s performance before undertaking one or several costly experimental test firings is important. On the numerical prediction side, as various component models evolve, their incorporation into an overall internal ballistics simulation program allows for new motor firing simulations to take place, which in turn allows for updated comparisons to experimental firing data. In the present investigation, utilizing an updated simulation program, the focus is on quasi-steady performance analysis and scale effects (influence of motor size). The predicted effects of negative/positive erosive burning and propellant/casing deflection, as tied to motor size, on a reference cylindrical-grain motor’s internal ballistics, are included in this evaluation. Propellant deflection has only a minor influence on the reference motor’s internal ballistics, regardless of motor size. Erosive burning, on the other hand, is distinctly affected by motor scale.

scholarly journals Scale Effects on Quasi-Steady Solid Rocket Internal Ballistic Behaviour

2021 ◽  
Author(s):  
David R. Greatrix
Keyword(s):  
Scale Effects ◽  
The Other ◽  
Simulation Program ◽  
Erosive Burning ◽  
Internal Ballistics ◽  
Minor Influence ◽  
Solid Rocket ◽  
Experimental Firing ◽  
A Minor ◽  
Component Models

The ability to predict with some accuracy a given solid rocket motor’s performance before undertaking one or several costly experimental test firings is important. On the numerical prediction side, as various component models evolve, their incorporation into an overall internal ballistics simulation program allows for new motor firing simulations to take place, which in turn allows for updated comparisons to experimental firing data. In the present investigation, utilizing an updated simulation program, the focus is on quasi-steady performance analysis and scale effects (influence of motor size). The predicted effects of negative/positive erosive burning and propellant/casing deflection, as tied to motor size, on a reference cylindrical-grain motor’s internal ballistics, are included in this evaluation. Propellant deflection has only a minor influence on the reference motor’s internal ballistics, regardless of motor size. Erosive burning, on the other hand, is distinctly affected by motor scale.

scholarly journals Long-Term Variability of Precipitation form in Hornsund (Spitsbergen) in Relation to Atmospheric Circulation (1979–2009)

2010 ◽  
Vol 3 (1) ◽  
pp. 65-86 ◽  
Author(s):  
Ewa Łupikasza
Keyword(s):  
Atmospheric Circulation ◽  
Arctic Oscillation ◽  
The Other ◽  
Solid Precipitation ◽  
Precipitation Characteristics ◽  
Minor Influence ◽  
A Minor ◽  
The Impact ◽  
Liquid Precipitation

Abstract The paper discusses the impact of the atmospheric circulation on the long-term variability of liquid, mixed and solid precipitation. The three precipitation forms were characterised by their totals, the number of days when they prevailed, and the contribution of each to the overall precipitation totals. Trends, as a background to further analysis, were calculated with regard to each characteristic of each precipitation form. The most significant increases were recorded in the contribution of liquid precipitation to the overall precipitation totals in September and in the mixed precipitation totals in December and November. Arctic Oscillation (AO) was found to have only a minor influence on the long-term variability of precipitation characteristics. The AO phase could to some degree account for the observed variation in the number of days with liquid precipitation. On the other hand, the direction of the local advection could account for considerably more of this variability and also the variability in liquid precipitation totals.

scholarly journals An Approach to Analysing Erosive Characteristics of Two-Channel Combustion Chambers

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yanjie Ma ◽  
Futing Bao ◽  
Weihua Hui ◽  
Yang Liu ◽  
Ran Wei
Keyword(s):  
Burning Rate ◽  
Solid Rocket Motor ◽  
Combustion Chambers ◽  
Erosive Burning ◽  
Flow Parameters ◽  
Threshold Phenomena ◽  
Internal Ballistics ◽  
Solid Rocket ◽  
Inner Channel ◽  
Good Agreement

To acquire the erosive characteristics of two-channel combustion chambers, a quasi-one-dimensional internal ballistics model is proposed. Combining the model with two different erosive burning models, the modified L-R expression, and the Mukunda-Paul expression, the flow parameters and the internal ballistics performance of a test solid rocket motor are computed. The results show good agreement with experimental data. According to the results, the more severe the erosion is, the earlier, longer, and gentler the tail-off stage becomes. During the tail-off stage, the dramatic drop of pressure leads to a low normal burning rate and makes it easier for erosion burning to occur. For this reason, notable erosive burning might appear during tail-off if the case-to-throat area ratio is extremely low. The results also show that flows in the inner channel and the outer channel are similar but not identical. This leads to different erosive burning behaviours in the two channels. Also, the two erosive burning rate models involved in this paper are compared. It seems that the M-P expression provides better results than the modified L-R expression does, since it reveals the threshold phenomena. Besides, the M-P expression has great advantages for its universality for most propellants and different SRM geometries.

THE EFFECT OF LOCATION ON NATURAL SELECTION IN BULK POPULATIONS OF BARLEY (HORDEUM VULGARE L.). I. SIMPLY INHERITED TRAITS

1980 ◽  
Vol 60 (1) ◽  
pp. 31-40 ◽  
Author(s):  
T. M. CHOO ◽  
H. R. KLINCK ◽  
C. A. ST-PIERRE
Keyword(s):  
Natural Selection ◽  
Hordeum Vulgare ◽  
The Other ◽  
Hordeum Vulgare L ◽  
Rates Of Change ◽  
Single Cross ◽  
Minor Influence ◽  
A Minor ◽  
Almost All

The effect of location on natural selection was investigated by studying the changes in phenotypic composition of six simply inherited traits. Seventeen F15 unselected bulk populations were derived from a single cross of barley. Fifteen of the bulks were alternated between Macdonald College and La Pocatière either annually or after 2–8 yr at one location; one of the remaining two bulks was grown continuously at Macdonald College and the other at La Pocatière. By F15, almost all populations had shifted toward plants with rough awns, yellow aleurone, short-haired rachillas, hairy rachis, or a dense spike. The V-shaped collar type predominated in these populations. The propagation environments had a significant effect on the rates of change in phenotypic composition of the six simply inherited traits in these barley bulk populations. However, the frequency of alternating populations between the two locations appeared to have only a minor influence on the rates of change in phenotypic composition of these traits.

Structure-activity relations and β-lactamase resistance

1980 ◽  
Vol 289 (1036) ◽  
pp. 197-205 ◽  
Keyword(s):  
Broad Spectrum ◽  
Product Inhibition ◽  
Sulphur Atom ◽  
Chemical Modifications ◽  
Gram Negative ◽  
Structure Activity ◽  
Broad Spectrum Resistance ◽  
Structure Activity Relations ◽  
Minor Influence ◽  
A Minor

β-Lactam antibiotics resistant to β-lactamase degradation can be produced by many chemical modifications, but often at the expense of antibacterial activity. Substitution onto several positions in the molecule produces different and often selective resistance; for instance, heavily sterically hindered acyl groups give staphylococcal P-lactamase resistance to penicillins, and resistance to some enzymes from Gram-negative pathogens to both penicillins and cephalosporins. 6-α- or 7-α-substituents respectively confer a broad spectrum of resistance (e.g. cefoxitin), but changes at positions 2 or 3 have only a minor influence on enzyme susceptibility. Changes in the ring condensed with the β-lactam, such as changing ceph-3-em to ceph-2-em may greatly enhance stability. Small improvements can occur when the nuclear sulphur atom is oxidized, but a much better effect is obtained when it is replaced by another atom such as oxygen, as in clavulanic acid. This compound appears to have broad spectrum resistance which is actually due to susceptibility and subsequent product inhibition.

Lubrication Properties of Aqueous Solutions with Polyethoxylated Ether (PEOE) Added

2011 ◽  
Vol 239-242 ◽  
pp. 1359-1363
Author(s):  
Chao Hui Zhang ◽  
Si Si Liu ◽  
Yue Tao Sun ◽  
Jun Ming Liu
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Metal Working ◽  
Functional Additives ◽  
Film Forming ◽  
Minor Influence ◽  
Forming Characteristics ◽  
Aqueous Surfactants ◽  
A Minor ◽  
Lubrication Properties

Aqueous solutions have found broad usages as lubricants, in conjunction with other possible utilizations, such as in metal working and other industries. Due to the inferior lubricity, functional additives are needed to improve their tribological performances among which aqueous surfactants are exclusively included. The film forming property of aqueous solution with polyethoxylated ether added (PEOE) is measured, taking consideration of the influences of the temperature and the concentration. The addition of PEOEs into aqueous solutions will largely increase the film forming capacity. But the concentration has only a minor influence on the lubrication property of the aqueous solutions with PEOEs. The cloud point will strongly alter the film forming characteristics.

A modified Runge-Kutta method

SIMULATION ◽  
1968 ◽  
Vol 10 (5) ◽  
pp. 221-223 ◽  
Author(s):  
A.S. Chai
Keyword(s):  
Error Estimate ◽  
Linear Combination ◽  
Experimental Results ◽  
The Other ◽  
New Method ◽  
Kutta Method ◽  
Starting Values ◽  
Runge Kutta Method ◽  
Runge Kutta ◽  
A Minor

It is possible to replace k2 in a 4th-order Runge-Kutta for mula (also Nth-order 3 ≤ N ≤ 5) by a linear combination of k1 and the ki's in the last step, using the same procedure for computing the other ki's and y as in the standard R-K method. The advantages of the new method are: It re quires one less derivative evaluation, provides an error estimate at each step, gives more accurate results, and needs a minor change to switch to the RK to obtain the starting values. Experimental results are shown in verification of the for mula.

scholarly journals II.—General Theorems on Determinants

1880 ◽  
Vol 29 (1) ◽  
pp. 47-54
Author(s):  
Thomas Muir
Keyword(s):  
The Other ◽  
Elementary Theorem ◽  
A Minor

The rows of a determinant of the nth order having been separated into two sets, one containing the first p rows and the other the rest, if each minor of the pth degree formed from the first set be multiplied by a minor, called its complementary, formed from the second set, and the result have its sign chosen in accordance with a certain law, it is well known as an elementary theorem that the aggregate of the products thus obtained is equal to the original determinant.

scholarly journals Influence of Different Commercial Yeasts on Volatile Fraction of Sparkling Wines

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 247
Author(s):  
Valeriu V. Cotea ◽  
Mihai Cristian Focea ◽  
Camelia Elena Luchian ◽  
Lucia Cintia Colibaba ◽  
Elena Cristina Scutarașu ◽  
...  
Keyword(s):  
International Organization ◽  
Volatile Fraction ◽  
Chemical Parameters ◽  
Physical Chemical ◽  
Organoleptic Characteristics ◽  
Mass Spectrometry Technique ◽  
Minor Influence ◽  
Spectrometry Technique ◽  
A Minor ◽  
Aging Stage

The occurrence of aroma constituents in sparkling wines, with direct impact on their organoleptic characteristics, is affected by several factors, for example the base-wine particularities, grapes cultivar conditions, inoculated yeasts, the aging stage, and wine-making practices. This study evaluated the influence of different four commercial yeasts (IOC FIZZ™, IOC DIVINE™, LEVULIA CRISTAL™, and IOC 18-2007™) on the volatile composition of experimental sparkling wines. For this, five sparkling wines variants from the Muscat Ottonel grape variety were obtained. The base-wine was obtained through reverse osmosis and had a predetermined alcoholic concentration (10.5% vol.). In order to fulfill the proposed purpose, the experimental sparkling wines were characterized by the physical–chemical parameters (according to International Organization of Vine and Wine methods of analysis), volatile fraction (using gas-chromatography coupled with mass spectrometry technique), and sensory descriptors. Data showed a key impact on the concentration of the volatile constituents (p < 0.05), depending on the type of inoculated yeast for the second fermentation. Regarding the sensory analysis, important differences can be observed due to the type of inoculated yeast. Only a minor influence on the physical–chemical parameters was registered.

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