scholarly journals Launch Bar Dynamics Character Analysis of Carrier-Based Aircraft Catapult Launch

2019 ◽  
Vol 9 (15) ◽  
pp. 3079
Author(s):  
Zhu ◽  
Lu ◽  
Yang ◽  
Ji ◽  
Han ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Working Condition ◽  
Center Of Gravity ◽  
Obvious Effect ◽  
Character Analysis ◽  
Driving Mechanisms ◽  
Study Results ◽  
Flight Deck

The launch bar is a unique device of carrier-based aircraft, which is connected to the nose gear and shuttle. In order to avoid the launch bar striking the flight deck after the launch bar pops out of the shuttle, it is very important to research the dynamics performance of the launch bar. This paper establishes a staged mathematical model of catapult launch including the launch bar, a steam-powered catapult, a holdback bar, and a carrier-based aircraft. This article studied the effect of the mass of the launch bar, restoring moment of the launch bar, and center of gravity position of the launch bar on the dynamics performance of the launch bar. The results showed the following: (1) we could reduce the risk collision of the launch bar and deck by reducing the mass of the launch bar, increasing the restoring moment, and shifting the center of gravity position of the launch bar; (2) under the working condition of this article, we changed the center of gravity position of the launch bar to control the sink of the launch bar end, having the most obvious effect, and we reduced the mass of the launch bar, having the least effect on controlling the sink of the launch bar end; however, reducing the mass of the launch bar could also greatly reduce the risk collision of the launch bar and deck; (3) in order to avoid the launch bar striking the flight deck, the restoring moment of the launch bar must overcome the sum of other moments. The study results can give a theoretical reference for designing and testing the launch bars of carrier-based aircraft. It can also give a theoretical reference for designing and testing the launch bar’s driving mechanisms.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals The possibilities of using group regression in the analysis of the diameter structure development in selection forests of Tara

2002 ◽  
pp. 79-89 ◽  
Author(s):  
Slobodanka Mitrovic ◽  
Stanisa Bankovic
Keyword(s):  
Mathematical Model ◽  
Future Development ◽  
Functional Dependence ◽  
Primary Objective ◽  
Structure Development ◽  
Study Results ◽  
The Future ◽  
Diameter Structure ◽  
Group Regression ◽  
Diameter Classes

Based on the presented study results, it can be concluded that the distribution of tree numbers per diameter degrees (diameter structure) in the four measurements of the compartments 51 and 75, did not change. It was also concluded that one functional dependence could be applied for both compartments N=e5,9?e?0,39*d The result of the above is that also in the following measurements, the diameter structure will remain unchanged, in cases of the same or similar selection cuttings both by the scope and by the distribution of felled trees per diameter classes The primary objective of this type of study is to predict, based on a mathematical model of diameter structure development, effect of the scope of selection cuttings and the number of recruitments on the diameter structure, and the simulation of growth, the distribution of trees per diameter classes in the following measurement or measurements, i.e. to foresee the future development of selection stands.

scholarly journals Introducing a particular mathematical model for predicting the resistance and performance of prismatic planing hulls in calm water by means of total pressure distribution

2015 ◽  
Vol 12 (2) ◽  
pp. 73-94 ◽  
Author(s):  
P. Ghadimi ◽  
S. Tavakoli ◽  
M. A. Feizi Chekab ◽  
A. Dashtimanesh
Keyword(s):  
Mathematical Model ◽  
Pressure Distribution ◽  
Total Pressure ◽  
Center Of Gravity ◽  
Governing Equations ◽  
Calm Water ◽  
Hydrodynamic Study ◽  
Pass Through ◽  
And Performance

Mathematical modeling of planing hulls and determination of their characteristics are the most important subjects in hydrodynamic study of planing vessels. In this paper, a new mathematical model has been developed based on pressure distribution. This model has been provided for two different situations: (1) for a situation in which all forces pass through the center of gravity and (2) for a situation in which forces don not necessarily pass through the center of gravity. Two algorithms have been designed for the governing equations. Computational results have been presented in the form of trim angle, total pressure, hydrodynamic and hydrostatic lift coefficients, spray apex and total resistance which includes frictional, spray and induced resistances. Accuracy of the model has been verified by comparing the numerical findings against the results of Savitsky's method and available experimental data. Good accuracy is displayed. Furthermore, effects of deadrise angle on trim angle of the craft, position of spray apex and resistance have been investigated.

scholarly journals Sodium Is Not Required for Chloride Efflux via Chloride/Bicarbonate Exchanger from Rat Thymic Lymphocytes

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Donatas Stakišaitis ◽  
Vaidevutis Meilus ◽  
Alfonsas Juška ◽  
Paulius Matusevičius ◽  
Janina Didžiapetrienė
Keyword(s):  
Mathematical Model ◽  
Wistar Rats ◽  
Relative Rate ◽  
Functional Characterization ◽  
Model Parameters ◽  
Study Results ◽  
Sodium Dependent ◽  
Male Wistar Rats ◽  
Relative Membrane Permeability ◽  
Extracellular Sodium

Sodium-dependent Cl−/HCO3-exchanger acts as a chloride (Cl−) efflux in lymphocytes. Its functional characterization had been described when Cl−efflux was measured upon substituting extracellular sodium (Na+) by N-methyl-D-glucamine (NMDG). For Na+and Cl−substitution, we have used D-mannitol or NMDG. Thymocytes of male Wistar rats aged 7–9 weeks were used and intracellular Cl−was measured by spectrofluorimetry using MQAE dye in bicarbonate buffers. Chloride efflux was measured in a Cl−-free buffer (Cl−substituted with isethionate acid) and in Na+and Cl−-free buffer with D-mannitol or with NMDG. The data have shown that Cl−efflux is mediated in the absence of Na+in a solution containing D-mannitol and is inhibited by H2DIDS. Mathematical modelling has shown that Cl−efflux mathematical model parameters (relative membrane permeability, relative rate of exchanger transition, and exchanger efficacy) were the same in control and in the medium in which Na+had been substituted by D-mannitol. The net Cl−efflux was completely blocked in the NMDG buffer. The same blockage of Cl−efflux was caused by H2DIDS. The study results allow concluding that Na+is not required for Cl−efflux via Cl−/HCO3-exchanger. NMDG in buffers cannot be used for substituting Na+because NMDG inhibits the exchanger.

Analysis and Calculation of Spud Clamshell Dredger’s Heeling

2014 ◽  
Vol 548-549 ◽  
pp. 406-409
Author(s):  
Han Bin Xiao ◽  
Kai Fa Lu ◽  
Shi Qing Lu
Keyword(s):  
Water Flow ◽  
Working Condition ◽  
High Technology ◽  
Center Of Gravity ◽  
Positioning Accuracy ◽  
Structural Part ◽  
Actual Working ◽  
Underwater Positioning ◽  
Geometrical Relationship

As a ship of high technology content, dredger is equipped with a very important structural part—spud. In actual working condition, spud is affected by seabed terrain and force of sediment. Moreover, water flow and wind will impact the hull. Consequently, the effect of moment of force on the hull’s center of gravity will cause heeling of the hull. This paper, with the help of geometrical relationship, is to quantificationally analyze and calculate the influence of transverse, longitudinal sloping and ordinary heeling on the underwater positioning accuracy of clamshell in the condition of heeling. Then it offers relevant compensation, in order to reduce the accuracy error of clamshell’s underwater positioning caused by hull’s heeling.

scholarly journals INFORMATION ANALYSIS OF ONLINE COLLABORATIVE COMPANY REVIEW

2021 ◽  
Vol 20 (2) ◽  
Author(s):  
Timothy Rey Laheba ◽  
The Jin Ai
Keyword(s):  
Working Condition ◽  
Information Analysis ◽  
Job Seekers ◽  
Life Balance ◽  
Job Description ◽  
Study Results ◽  
Basic Salary ◽  
The Relationship ◽  
A Company

In this era of industry 4.0, the role of technology is getting bigger and broader in the industry. This technology has changed some of the old habits and paradigms in the relationship between companies and job seekers. One of the changes currently occurring is that job seekers can find information related to a company through an online collaborative company review which can be found easily on the employment website. This study aims to determine what information job seekers consider essential from an online collaborative review of a company. Data from the 203 millennial generations in Indonesia were collected. The study results found that the most sought-after variable from an online collaborative company review was Basic salary exposition, followed by Job description. The following variable is Work-life balance or working condition, followed by the Company profile variable, Benefits and incentives, Positive things about a company, and negative things about a company.

scholarly journals Prediction of Suicidal Behavior in Students at Military Academies

Doctor Ru ◽  
2020 ◽  
Vol 19 (9) ◽  
pp. 65-70
Author(s):  
K.V. Dnov ◽  
◽  
A.I. Kolchev ◽  
D.А. Seregin ◽  
V.K. Mikhalsky ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Suicidal Behavior ◽  
Suicide Risk ◽  
Well Being ◽  
Semantic Differential ◽  
Naval Academy ◽  
Study Objective ◽  
Self Reflection ◽  
Study Results ◽  
Military Academies

Study Objective: To develop a mathematical model for predicting suicide risk in students at military academies. Study Design: This was a comparative prospective study. Materials and Methods: One hundred and thirty-three students at the Naval Polytechnic Institute, a subdivision of the Naval Academy named for the Admiral of the Fleet of the Soviet Union N.G. Kuznetsov, participated in the study. Assessment of the participants was done with the following tools: “The Ratio of Value and Accessibility in Various Areas of Life,” “Self-reflection Test,” “Semantic Differential,” “Military Occupational Aptitude,” and the “Mental Well-being Scale” questionnaire. Discriminative analysis was done to develop a mathematical model for predicting suicide risk. Study Results: Participants at high risk for suicide had scores for their personal emotional attitude towards the concepts “military service” and “ego ideal” that were lower by a statistically significant margin (p<0.05), and higher levels of self-reflection. In addition, more of them had intrapsychic conflict. The combination of these psychological characteristics was a risk factor for suicidal behavior in these military academy students. Conclusion: An informative model for predicting suicide risk in naval academy students was created, using discriminant modelling. Keywords: suicide risk, prediction, officer trainee, semantic differential, military servicemen

scholarly journals Method for determining the spatial position of the center of gravity of machines

2019 ◽  
pp. 71-82
Author(s):  
I. A. Blinov
Keyword(s):  
Mathematical Model ◽  
Computer Model ◽  
Center Of Gravity ◽  
Spatial Position ◽  
Coordinate Method ◽  
The Core ◽  
Measurement Results ◽  
Minimum Number ◽  
Mathematical Processing ◽  
Processing Of Measurement Results

Having analyzed traditional methods for determining the coordinates of the center of gravity of machines, we developed a three-coordinate method using the simplest and most affordable means of hanging products with a crane beam. The method differs from analogues in the minimum number of weighings when there are no force-measuring means as a component of the measuring circuit. We introduce a mathematical model, which is the core of the method, and a computer model which minimizes the complexity of mathematical processing of measurement results

scholarly journals Transport category airplane flight range calculation accounting center-of-gravity position shift and engine throttling characteristics

2021 ◽  
pp. 4-14
Author(s):  
Ruslan Tsukanov ◽  
Viktor Riabkov
Keyword(s):  
Mathematical Model ◽  
Fuel Consumption ◽  
Program Implementation ◽  
Fuel Efficiency ◽  
Real Data ◽  
Center Of Gravity ◽  
Specific Fuel Consumption ◽  
Flight Range ◽  
Position Shift ◽  
Range Calculation

A problem facing world commercial aviation is a provision of the flight range and an increase in the fuel efficiency of transport category airplanes using fuel trim transfer application, which allows for decreasing airplane trim drag at cruise flight. In the existing mathematical models, center-of-gravity position is usually assumed fixed, but with fuel usage, center-of-gravity shifts within the definite range of center-of-gravity positions. Until the fuel trim transfer was not used in airplanes, the center-of-gravity shift range was rather short, that allowed to use the specified assumption without any considerable mistakes. In case of fuel trim transfer use, center-of-gravity shifts can reach 15…20 % of mean aerodynamic chord, that requires considering the center-of-gravity actual position during the flight range calculation. Early made estimated calculations showed the necessity of following mathematical model improvement using accounting the real engine throttling characteristics. The goal of this publication is to develop a method of flight range calculation taking transport category airplane into account actual center-of-gravity position with fuel using and variation in engine-specific fuel consumption according to their throttling characteristics. On the basis of real data from engine maintenance manuals, formulas are obtained for approximation throttling characteristics of turbofan engines in the form of dimensionless specific fuel consumption (related to the specific fuel consumption at full thrust) dependence on the engine throttling coefficient. A mathematical model (algorithm and its program implementation using С language in Power Unit 11.7 R03 system) has been developed to calculate the airplane flight range accounting its actual center-of-gravity position shift with fuel usage and variation in specific fuel consumption according to engine throttling characteristics. Using comparison with known payload-range diagram, adequacy of developed mathematical model is shown. Recommendations to improve the mathematical model are also given.

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