The paper intend to develop a calculus model for an innovative Reaction Control System (RCS) using hybrid rocket engine technology. Our RCS uses several hybrid micro-thrusters with their thrust modulated by a separate...
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ISBN:
(纸本)9781467363969;9781467363952
The paper intend to develop a calculus model for an innovative Reaction Control System (RCS) using hybrid rocket engine technology. Our RCS uses several hybrid micro-thrusters with their thrust modulated by a separate control system. For RCS, each of the thrusters will be able to burn a few minutes and its thrust will be modulated within certain limits by controlling the oxidizer flow. In order to reduce size and weight of the RCS we will use a single oxidizer tank which will have as output a flow distributor. The basic idea is not to stop any of the engines during system's operation but to minimize their thrust reducing the oxidizer flow. This approach is avoiding the inconvenience of repeated stopping and starting of the engine, which can create reliability problems to the entire RCS. By creating thrust imbalance between various hybrid micro thrusters, one can create torques with which the attitude or the trajectory of the vehicle can be adjusted. In terms of calculation model developed, it starts from our theoretical and experimental studies, which aimed to build a computational model for hybrid rocket engine highlighting the scalability, stability and its controllability. These studies were presented in RAST 2011 and are based on our own experiments performed in Electromecanica Ploiesti. Based on this concept we achieve a calculation of the performances of the RCS and an evaluation in their size. Conclusions and any discussion will be focused on technological possibilities for achieving the system and possible areas of application for the RCS.
In this paper, a homotopy-based method is employed for the recovery of speech recordings from missing or corrupted samples taken in a noisy environment. The model for the acquisition device is a compressed sensing sce...
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ISBN:
(纸本)9783319394404;9783319394411
In this paper, a homotopy-based method is employed for the recovery of speech recordings from missing or corrupted samples taken in a noisy environment. The model for the acquisition device is a compressed sensing scenario using Gabor frames. To recover an approximation of the speech file, we used the basis pursuit denoising method with the homotopy continuation algorithm. We tested the proposed method with various speech recordings.
Traffic-induced vibrations may cause various damages to buildings located near the road, including cracking of plaster, cracks in load-bearing elements or even collapse of the whole structure. Measurements of vibratio...
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ISBN:
(纸本)9783030504205;9783030504199
Traffic-induced vibrations may cause various damages to buildings located near the road, including cracking of plaster, cracks in load-bearing elements or even collapse of the whole structure. Measurements of vibrations of real buildings are costly and laborious. Therefore the aim of the research is to propose the original numerical algorithm which allows us to predict, with high probability, the negative dynamic impact of traffic-induced vibrations on the examined building. The model has been based on machine learning. Firstly, the experimental tests have been conducted on different buildings using specialized equipment taking into account six factors: distance from the building to the edge of the road, type of surface, condition of road surface, condition of the building, the absorption of soil and the type of vehicle. Then, the numerical algorithm based on machine learning (using support vector machine) has been created. The results of the conducted analysis clearly show that the method can be considered as a good tool for predicting the impact of traffic-induced vibrations on buildings, being characterized by high reliability.
The problem of building a numerical algorithm for determination of branching points of one nonlinear integral operator, which arises in the theory of antennas synthesis according to the given amplitude radiation patte...
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ISBN:
(纸本)0780378814
The problem of building a numerical algorithm for determination of branching points of one nonlinear integral operator, which arises in the theory of antennas synthesis according to the given amplitude radiation pattern, is considered. The basic difficulty, consists in that the kernel of an integral operator nonlinearly depends oil two parameters, which play role of the spectral ones. For such problems, except a special case. the existing numerical algorithms are not applicable. For building an algorithm for solving such problems, the equivalent variational statement is used. The problem is reduced to a sequence of linear two-parameter eigenvalue problems with application of one gradient procedure for simultaneous evaluation of two spectral parameters being the branching points of an initial nonlinear integral operator.
Collatz conjecture (or 3x+1 problem) has been explored for about 80 years. By now the largest number that has been verified for Collatz conjecture is about 60 bits. In this paper, we propose new algorithms that can ve...
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ISBN:
(纸本)9781538693803
Collatz conjecture (or 3x+1 problem) has been explored for about 80 years. By now the largest number that has been verified for Collatz conjecture is about 60 bits. In this paper, we propose new algorithms that can verify much greater numbers than known algorithms, i.e., about 100000 bits (30000 digits) on whether they can return 1 after 3*x+1 and x/2 computations. The proposed algorithms change numerical computation to bit computation (or logical computation), and change inner memory data representation to hard disk file manipulation. We make it possible to verify extremely large numbers without concerning computer memory upper-bound. The largest number verified for Collatz conjecture until now in the world is 2(100000) - 1, and this magnitude of extremely large numbers has never been verified. We discovered that this number can return to 1 after 481603 times of 3*x+1 computation, and 863323 times of x/2 computation. At last, we stress that some open problems may be used for the green mining in blockchain-based cryptocurrencies, e.g., BTC. We discuss the applicability of Collatz conjecture for the Proof of Work in Blockchain.
Use of the technique of generalized scattering matrices is convenient for solving complicated problems of scattering on the base of decomposition principle. Use of this principle in commonly accepted versions, when th...
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ISBN:
(纸本)9660200269
Use of the technique of generalized scattering matrices is convenient for solving complicated problems of scattering on the base of decomposition principle. Use of this principle in commonly accepted versions, when the decomposition is carried out into characteristic simple segments of common topology (key blocks), is obvious. However in a number of cases decomposition can be successfully applied while modeling the structures, in which some key blocks are not evident. It is shown earlier that, while modeling key blocks by the momentum method at essentially different dimensions of the channels being connected, one can increase calculation accuracy by means of the decomposition of the element into two virtual ones. This idea is realized in this paper in the version, accounting the character of momentum method solution more completely.
A study is made of the problem of the displacement of one fluid by another with the formation of a region of combined flow in the case of an elastic flow regime in the region of the displaced fluid. A self-similar sol...
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Consider a Markov-modulated G/G/1 queueing system in which the arrival and the service mechanisms are controlled by an underlying Markov chain. The classical approaches to the waiting time of this type of queueing sys...
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In this study, we introduce the concepts of modular Reich-type and modular Chatterjea-type nonexpansive mappings, as natural extensions of their definitions from normed vector spaces to modular vector spaces. After de...
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In this study, we introduce the concepts of modular Reich-type and modular Chatterjea-type nonexpansive mappings, as natural extensions of their definitions from normed vector spaces to modular vector spaces. After describing the two modular conditions and emphasize their role through some examples, we use them in connection with an iteration procedure for obtaining some fixed point convergence-related conclusions. In addition, a connection between modular Chatterjea-type nonexpansive mappings and Takahashi hybrid operators is analyzed. As a remarkable application, we incorporate modular Reich-type and modular Chatterjea-type nonexpansive mappings together with the iteration process into a modular proximal setting and state some best proximity point results.
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