The Research on the Launching Consistence of Small Caliber Electromagnetic Railgun

2012 ◽  
Vol 220-223 ◽  
pp. 565-570
Author(s):  
Yi Zhang ◽  
Chun Xia Yang ◽  
Hai Yuan Li ◽  
Bao Ming Li
Keyword(s):  
Long Range ◽  
The Other ◽  
Initial Value ◽  
Manufacturing Error ◽  
The Stability

Electromagnetic railgun can perform precision strike in long range. It is obtained that the scatter of velocity must be exist because there are many effectors influencing launching process, for example, the manufacturing error, the initial value of launching parameters and uncertainty during launching process and so on. Among these factors, the parameters of armature are easy to adjust to ensure the consistence of velocity. So we attempt to apply Grey Analyzing Model to carry on the study, and then by means of the measurement of strain on the barrel to verify the model. The result shows that the reasonable matching of armature mass and diameter can be helpful to improve the consistence of armature muzzle with the other parameters the same. This method is a new attempt to study the stability and consistence of velocity of solid armature.

Stability of time-dependent rotational Couette flow Part 2. Stability analysis

1971 ◽  
Vol 48 (2) ◽  
pp. 365-384 ◽  
Author(s):  
C. F. Chen ◽  
R. P. Kirchner
Keyword(s):  
Growth Rate ◽  
Stability Analysis ◽  
Kinetic Energy ◽  
Initial Value Problem ◽  
Basic Flow ◽  
The Other ◽  
Time Dependent ◽  
Stability Criteria ◽  
Initial Value ◽  
The Stability

The stability of the flow induced by an impulsively started inner cylinder in a Couette flow apparatus is investigated by using a linear stability analysis. Two approaches are taken; one is the treatment as an initial-value problem in which the time evolution of the initially distributed small random perturbations of given wavelength is monitored by numerically integrating the unsteady perturbation equations. The other is the quasi-steady approach, in which the stability of the instantaneous velocity profile of the basic flow is analyzed. With the quasi-steady approach, two stability criteria are investigated; one is the standard zero perturbation growth rate definition of stability, and the other is the momentary stability criterion in which the evolution of the basic flow velocity field is partially taken into account. In the initial-value problem approach, the predicted critical wavelengths agree remarkably well with those found experimentally. The kinetic energy of the perturbations decreases initially, reaches a minimum, then grows exponentially. By comparing with the experimental results, it may be concluded that when the perturbation kinetic energy has grown a thousand-fold, the secondary flow pattern is clearly visible. The time of intrinsic instability (the time at which perturbations first tend to grow) is about ¼ of the time required for a thousandfold increase, when the instability disks are clearly observable. With the quasi-steady approach, the critical times for marginal stability are comparable to those found using the initial-value problem approach. The predicted critical wavelengths, however, are about 1½ to 2 times larger than those observed. Both of these points are in agreement with the findings of Mahler, Schechter & Wissler (1968) treating the stability of a fluid layer with time-dependent density gradients. The zero growth rate and the momentary stability criteria give approximately the same results.

Uniformity of Magnification from Different Electron Microscopes

1967 ◽  
Vol 25 ◽  
pp. 32-33
Author(s):  
Godfrey C. Hoskins ◽  
V. Williams ◽  
V. Allison
Keyword(s):  
Diffraction Grating ◽  
The Other ◽  
Carbon Replica ◽  
Electron Microscopes ◽  
The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

scholarly journals Black Hole Algorithm for Sustainable Design of Counterfort Retaining Walls

2020 ◽  
Vol 12 (7) ◽  
pp. 2767 ◽  
Author(s):  
Víctor Yepes ◽  
José V. Martí ◽  
José García
Keyword(s):  
Black Hole ◽  
Sustainable Design ◽  
Retaining Walls ◽  
The Other ◽  
Trade Off ◽  
Construction Company ◽  
Geometric Variables ◽  
The Stability ◽  
The Cost ◽  
Black Hole Algorithm

The optimization of the cost and CO 2 emissions in earth-retaining walls is of relevance, since these structures are often used in civil engineering. The optimization of costs is essential for the competitiveness of the construction company, and the optimization of emissions is relevant in the environmental impact of construction. To address the optimization, black hole metaheuristics were used, along with a discretization mechanism based on min–max normalization. The stability of the algorithm was evaluated with respect to the solutions obtained; the steel and concrete values obtained in both optimizations were analyzed. Additionally, the geometric variables of the structure were compared. Finally, the results obtained were compared with another algorithm that solved the problem. The results show that there is a trade-off between the use of steel and concrete. The solutions that minimize CO 2 emissions prefer the use of concrete instead of those that optimize the cost. On the other hand, when comparing the geometric variables, it is seen that most remain similar in both optimizations except for the distance between buttresses. When comparing with another algorithm, the results show a good performance in optimization using the black hole algorithm.

scholarly journals A Fractional SAIDR Model in the Frame of Atangana–Baleanu Derivative

2021 ◽  
Vol 5 (2) ◽  
pp. 32
Author(s):  
Esmehan Uçar ◽  
Sümeyra Uçar ◽  
Fırat Evirgen ◽  
Necati Özdemir
Keyword(s):  
Existence And Uniqueness ◽  
Laplace Transformation ◽  
Cell Phones ◽  
Mobile Network ◽  
The Other ◽  
Banach Fixed Point Theorem ◽  
Propagation Models ◽  
Computer Worms ◽  
Computer Viruses ◽  
The Stability

It is possible to produce mobile phone worms, which are computer viruses with the ability to command the running of cell phones by taking advantage of their flaws, to be transmitted from one device to the other with increasing numbers. In our day, one of the services to gain currency for circulating these malignant worms is SMS. The distinctions of computers from mobile devices render the existing propagation models of computer worms unable to start operating instantaneously in the mobile network, and this is particularly valid for the SMS framework. The susceptible–affected–infectious–suspended–recovered model with a classical derivative (abbreviated as SAIDR) was coined by Xiao et al., (2017) in order to correctly estimate the spread of worms by means of SMS. This study is the first to implement an Atangana–Baleanu (AB) derivative in association with the fractional SAIDR model, depending upon the SAIDR model. The existence and uniqueness of the drinking model solutions together with the stability analysis are shown through the Banach fixed point theorem. The special solution of the model is investigated using the Laplace transformation and then we present a set of numeric graphics by varying the fractional-order θ with the intention of showing the effectiveness of the fractional derivative.

scholarly journals Competing Conventions with Costly Information Acquisition

Games ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 53
Author(s):  
Roberto Rozzi
Keyword(s):  
Information Acquisition ◽  
Evolutionary Model ◽  
Equilibrium Selection ◽  
The Other ◽  
Group Interactions ◽  
Social Coordination ◽  
Long Run ◽  
Stochastic Stability Analysis ◽  
The Stability ◽  
The Cost

We consider an evolutionary model of social coordination in a 2 × 2 game where two groups of players prefer to coordinate on different actions. Players can pay a cost to learn their opponent’s group: if they pay it, they can condition their actions concerning the groups. We assess the stability of outcomes in the long run using stochastic stability analysis. We find that three elements matter for the equilibrium selection: the group size, the strength of preferences, and the information’s cost. If the cost is too high, players never learn the group of their opponents in the long run. If one group is stronger in preferences for its favorite action than the other, or its size is sufficiently large compared to the other group, every player plays that group’s favorite action. If both groups are strong enough in preferences, or if none of the groups’ sizes is large enough, players play their favorite actions and miscoordinate in inter-group interactions. Lower levels of the cost favor coordination. Indeed, when the cost is low, in inside-group interactions, players always coordinate on their favorite action, while in inter-group interactions, they coordinate on the favorite action of the group that is stronger in preferences or large enough.

Estimation of the Stability of Acoustic Reciprocal Transmission in Long-Range Propagation at the Central Equatorial Pacific

2002 ◽  
Vol 41 (Part 1, No. 5B) ◽  
pp. 3525-3529 ◽  
Author(s):  
Yong Wang ◽  
Hiroyuki Hachiya ◽  
Toshiaki Nakamura ◽  
Iwao Nakano
Keyword(s):  
Long Range ◽  
Equatorial Pacific ◽  
Central Equatorial Pacific ◽  
The Stability

Estimation of the Stability of Acoustic Multipath in Long-Range Propagation at the Western Equatorial Pacific

1999 ◽  
Vol 38 (Part 1, No. 5B) ◽  
pp. 3366-3369 ◽  
Author(s):  
Hiroyuki Hachiya ◽  
Toshiaki Nakamura ◽  
Iwao Nakano
Keyword(s):  
Long Range ◽  
Equatorial Pacific ◽  
Western Equatorial Pacific ◽  
The Stability

LONG DURATION ECHOES FROM AURORA, METEORS, AND IONOSPHERIC BACK-SCATTER

1953 ◽  
Vol 31 (2) ◽  
pp. 171-181 ◽  
Author(s):  
D. W. R. McKinley ◽  
Peter M. Millman
Keyword(s):  
Long Range ◽  
High Frequency ◽  
The Other ◽  
Very High Frequency ◽  
Long Duration ◽  
E Region ◽  
Very High ◽  
Visual Observations

In the course of the Ottawa meteor program some unusual echoes have been detected on 33 Mc. Echoes from the aurora are discussed and correlated with visual observations. Two mechanisms of radio reflections from the aurora have been proposed but the data here presented are insufficient to favor one over the other. On Aug. 4, 1948, six extremely long duration meteor echoes were observed which may have been due to abnormal ionospheric conditions. From time to time since August, 1948, a weak semipermanent echo has been recorded, usually appearing at a range of about 80 km., and enduring up to an hour. It is suggested that this echo is due to back-scatter from the same sources in the lower E-region that are presumed to be responsible for long-range very high frequency propagation.

A Biomechanical Evaluation of Three Forms of Internal Fixation Used in Ankle Arthrodesis

1994 ◽  
Vol 15 (6) ◽  
pp. 297-300 ◽  
Author(s):  
Michael P. Dohm ◽  
James B. Benjamin ◽  
Jeffrey Harrison ◽  
John A. Szivek
Keyword(s):  
Internal Fixation ◽  
Plate Fixation ◽  
Ankle Arthrodesis ◽  
Biomechanical Study ◽  
The Other ◽  
Fixation Failure ◽  
Plate Group ◽  
Biomechanical Evaluation ◽  
The Stability ◽  
Fibular Strut

A biomechanical study was undertaken to evaluate the relative stability of three types of internal fixation used for ankle arthrodesis. Crossed screw fixation, RAF fibular strut fixation, and T-plate fixation were tested in 30 cadaver ankles using an MTS machine. T-plate fixation consistantly provided the stiffest construct when compared with the other types of fixation. Failure occurred by distraction of bony surfaces, posterior to the plane of fixation, in the crossed screw and RAF groups. In contrast, failure in the T-plate group occurred through compression of bone anterior to the midcoronal plane of the tibia. Although the stability of fixation is only one factor in determining the success or failure of ankle arthrodesis, the results of this study would support T-plate fixation over the other forms tested.

scholarly journals Tetracycline Induces Stabilization of mRNA in Bacillus subtilis

2002 ◽  
Vol 184 (4) ◽  
pp. 889-894 ◽  
Author(s):  
Yi Wei ◽  
David H. Bechhofer
Keyword(s):  
Bacillus Subtilis ◽  
Mrna Stability ◽  
The Other ◽  
Leader Region ◽  
Subinhibitory Concentration ◽  
Coding Sequence ◽  
Mrna Stabilization ◽  
Threefold Increase ◽  
The Stability

ABSTRACT The tet(L) gene of Bacillus subtilis confers low-level tetracycline (Tc) resistance. Previous work examining the >20-fold-inducible expression of tet(L) by Tc demonstrated a 12-fold translational induction. Here we show that the other component of tet(L) induction is at the level of mRNA stabilization. Addition of a subinhibitory concentration of Tc results in a two- to threefold increase in tet(L) mRNA stability. Using a plasmid-borne derivative of tet(L) with a large in-frame deletion of the coding sequence, the mechanism of Tc-induced stability was explored by measuring the decay of tet(L) mRNAs carrying specific mutations in the leader region. The results of these experiments, as well as experiments with a B. subtilis strain that is resistant to Tc due to a mutation in the ribosomal S10 protein, suggest different mechanisms for the effects of Tc on translation and on mRNA stability. The key role of the 5" end in determining mRNA stability was confirmed in these experiments. Surprisingly, the stability of several other B. subtilis mRNAs was also induced by Tc, which indicates that addition of Tc may result in a general stabilization of mRNA.

Sign in / Sign up

Export Citation Format

Share Document