Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 12
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

The present study has been taken up to emphasize the role of the hybridization process for optimizing a given reinforced concrete (RC) frame. Although various primary techniques have been hybrid in the past with varying degree of success, the effect of hybridization of enhanced versions of standard optimization techniques has found little attention. The focus of the current study is to see if it is possible to maintain and carry the positive effects of enhanced versions of two different techniques while using their hybrid algorithms. For this purpose, enhanced versions of standard particle swarm optimization (PSO) and a standard gravitational search algorithm (GSA), were considered for optimizing an RC frame. The enhanced version of PSO involves its democratization by considering all good and bad experiences of the particles, whereas the enhanced version of the GSA is made self-adaptive by considering a specific range for certain parameters, like the gravitational constant and a set of agents with the best fitness values. The optimization process, being iterative in nature, has been coded in C++. The analysis and design procedure is based on the specifications of Indian codes. Two distinct advantages of enhanced versions of standard PSO and GSA, namely, better capability to escape from local optima and a faster convergence rate, have been tested for the hybrid algorithm. The entire formulation for optimal cost design of a frame includes the cost of beams and columns. The variables of each element of structural frame have been considered as continuous and rounded off appropriately to consider practical limitations. An example has also been considered to emphasize the validity of this optimum design procedure.

Go to article

Authors and Affiliations

Sonia Chutani
Jagbir Singh
Download PDF Download RIS Download Bibtex

Abstract

The purpose of this paper is to generate cryptographically strong elliptic curves over prime fields Fp, where p is a Mersenne prime, one of the special primes or a random prime. We search for elliptic curves which orders are also prime numbers. The cryptographically strong elliptic curves are those for which the discrete logarithm problem is computationally hard. The required mathematical conditions are formulated in terms of parameters characterizing the elliptic curves.We present an algorithm to generate such curves. Examples of elliptic curves of prime order are generated with Magma.
Go to article

Bibliography

[1] Daniel J. Bernstein and Tanja Lange. SafeCurves: choosing safe curves for elliptic curve cryptography, 2015. http://safecurves.cr.yp.to (accessed 27 September 2015).
[2] I. Blake, G. Serroussi, N. Smart. Elliptic curves in cryptography. Cambridge University Press, 1999.
[3] H. Cohen. A course in computational number theory. Springer 1983.
[4] H. Cohen, G. Frey. Handbook of Elliptic and Hyperelliptic Curve Cryptography. Chapman and Hall CRC, 1994.
[5] P. Da˛browski, R. Gliwa, J. Szmidt, R. Wicik. Generation and Implementation of Cryptographically Strong Elliptic Curves. Number-Theoretical Methods in Cryptology. First International Conference, NuTMiC 2017. Warsaw, Poland, 11-13, 2017. Lecture Notes in Computer Sciences, (Eds), Jerzy Kaczorowski, Josef Piprzyk, Jacek Pomykała. Volume 10737, pages 25-36. 2017.
[6] W. Diffie, M. E. Hellman. New Directions in Cryptography. IEEE Trans. Information Theory, IT 22(6), pp. 644-654, 1976.
[7] Jean-Pierre Flori, Jerome Plut, Jean-Rene Reinhard. Diversity and transparency for ECC. NIST Workshop on ECC Standards, June 11-12, 2015.
[8] Gerhard Frey, private communication, 2015.
[9] G. Frey, H. Rück. A remark concerning m-divisibility and the discrete logarithm in the divisor class group of curves. Mathematics of Computations, 62 91994), 865-874.
[10] S. D. Galbraith, P. Gaudry. Recent progress on the elliptic curve discrete logarithm problem. Cryptology ePrint Archive, 2015/1022.
[11] Steven D. Galbraith and James McKee. The probability that the number of points on an elliptic curve over a finite field is prime. J. London Math. Soc. (2), 62(3):671–684, 2000.
[12] R. Gliwa, J. Szmidt, R. Wicik Searching for cryptographically secure elliptic curves over prime fields. Science and Military, 2016, nr 1, volume 11, pages 10-13, ISSN 1336-8885 (print), ISSN 2453-7632 (on-line).
[13] R. Granger, M. Scott. Faster ECC over F2521��1. In: Katz, J. ed., PKC 2015. LNCS, vol. 9020, pp. 539–553.[14] D. Johnson, A. Menezes. The Elliptic Curve Digital Signature Algorithm (ECDSA). Technical Report CORR 99-34, University of Waterloo, Canada. http://www.math.uwaterloo.ca
[15] Manfred Lochter and Andreas Wiemers. Twist insecurity, 2015. iacr. ePrint Archive 577 (2015).
[16] A. Menezes, T. Okamoto, S. Vanstone. Reducing elliptic curve logarithms to logarithms in a finite field. IEEE. Transactions on Information Theory, 39 (1993), 1639-1646.
[17] N. Koblitz. Elliptic curve cryptosystems. Math. Comp., 48(177), pp. 203- 209, 1987.
[18] V. S. Miller. Use of elliptic curves in cryptography. In Advances in Cryptology - CRYPTO’85, LNCS vol 218, pp. 417-426, 1985.
[19] P. Pohlig, M. Hellman. An improved algorithm for computing logarithms over GF(p) and its cryptographic significance. IEEE Transaction on Information Theory, 24 (1979), 106-110.
[20] J. Pollard. Monte Carlo methods for index computations mod pn: Mathematics of Computations, 32 (1978), 918-924.
[21] R. L. Rivest, A. Shamir, L. Adleman. A method for obtaining digital signatures and public-key cryptosystems. Comm. ACM, 21(2), pp. 120- 126, 1978.
[22] T. Satoh, K. Araki. Fermat quotients and the polynomial time discrete log algorithm for anomalous elliptic curves, Commentarii Mathematici Universitatis Sancti Pauli, 47 (1998), 81-92.
[23] I. Semaev. Evaluation of discrete logarithms in a group of p-torsion points of an elliptic curve in characteristic p. Mathematics of Computations, 67 (1998), 353-356.
[24] N. Smart. The discrete logarithm problem on elliptic curves uf trace one. Journal of Cryptology, 12 (1999), 193-196.
[25] J. H. Silverman. The arithmetic of elliptic curves. Springer 1986.
[26] Elliptic Curve Cryptography (ECC) Brainpool Standard. Curves and Curve Generation, v. 1.0. 2005. Request for Comments: 5639, 2010. 7027, 2013. http://www.bsi.bund.de
[27] Technical and Implementation Guidance on Generation and Application of Elliptic Curves for NATO classified, 2010.
[28] US Department of Commerce. N.I.S.T. 2000. Federal Information Processing Standards Publication 186-2. FIPS 186-2. Digital Signature Standard.
[29] Standards for Efficient Cryptography Group. Recommended elliptic curve domain parameters, 2000. www.secg.org/collateral/sec2.pdf
[30] Mersenne prime. en.wikipedia.org
[31] Magma Computational Algebra System. School of Mathematics and Statistics. University of Sydney.
Go to article

Authors and Affiliations

Marcin Barański
1
Rafał Gliwa
1
Janusz Szmidt
1

  1. Military Communication Institute, National Research Institute, Warszawska 22A, 05-130 Zegrze
Download PDF Download RIS Download Bibtex

Abstract

PID controllers are crucial for industrial control because of their simple structure and good robustness. In order to further improve the accuracy of PID controllers, this paper proposes an improved sparrow search algorithm (ISSA) to prevent the problem of the algorithm being prone to falling into the local optimum at the late stage of iteration. Based on the standard sparrow search algorithm, the position update formula and the step size control parameter are optimized to help quickly jump out of the local, and to obtain the optimal solution in the whole domain. Finally, to verify the accuracy and stability of the improved algorithm, nine standard test functions are first simulated. Then, the PID parameter optimization tests are finished with the chilled water and battery charging systems, where the lifting load and applying perturbation are carried out. Both the simulation and test results show that ISSA improves the convergence speed and accuracy, and performs better in terms of stability.
Go to article

Authors and Affiliations

Mingfeng Zhang
1
Chuntian Xu
1
ORCID: ORCID
Deying Xu
1
Guoqiang Ma
1
Han Han
2
Xu Zong
3

  1. School of Mechanical Engineering and Automation, University of Science and Technology Liaoning, Anshan, Liaoning, China
  2. College of Science – Computer Science, University of Arizona, Tucson, Arizona, USA
  3. Angang Steel Co. LTD, Anshan Iron & Steel, Anshan, Liaoning, China
Download PDF Download RIS Download Bibtex

Abstract

Nowadays, the development of smart grids has been the focus of attention due to its advantages for power systems. One of the aspects of smart grids defined by using distributed generation (DG) in a low voltage network is a microgrid (MG). Based on its operational states, MG can operate in different configurations such as grid-connected mode or off-grid mode. The switching between these states is one of the challenging issues in this technical area. The fault currents in different buses have higher value compared to islanded mode of MG when the MG is connected to the main grid, which influences the protection equipment. In this situation, some electrical devices may be damaged due to the fault currents. Application of a fault current limiter (FCL) is considered as an effective way to overcome this challenge. The optimal size of these FCLs can optimize the performance of an MG. In this paper, an index for FCL size optimization has been used. In addition, two optimization algorithms (Bat Algorithm and Cuckoo Search Algorithm) have been applied to the problem. The application of an FCL has been studied in grid-connected and islanded-mode. In addition, the application of the capacitor bank in both modes has been investigated. The results of simulations carried out by MATLAB have been presented and compared.
Go to article

Authors and Affiliations

Ali Asghar Khodadoost Arani
N. Bayati
Reza Mohammadi
G.B. Gharehpetian
S.H. Sadeghi
Download PDF Download RIS Download Bibtex

Abstract

This article validates the application of RT-Lab for the AGC studies of three-area systems. All the areas are employed with thermal-DSTS systems. A new controller named cascade FOPDN-FOPPIDN is employed. Its parameters are optimized using a CSA, subjecting to a new PI named HPA-ISE. The responses of the FOPDN-FOPIDN controller are related and are superior over PIDN and TIDN controllers. Moreover, the dominance of HPA-ISE is verified with ISE, and it performs better in terms of system dynamics. Further, the system performance reliability is analyzed with the AC-HVDC and is better than the AC system. Besides, sensitivity analysis recommends that the proposed FOPDN-FOPIDN at diverse conditions is robust and more reliability.
Go to article

Authors and Affiliations

Naladi Ram Babu
1
Tirumalasetty Chiranjeevi
2
Ramesh Devarapalli
3
ORCID: ORCID
Łukasz Knypiński
4
ORCID: ORCID
Fausto Pedro Garcìa Màrquez
5

  1. Department of Electrical and Electronics Engineering, Aditya Engineering College, Surampalem, Andhra Pradesh, India
  2. Department of Electrical Engineering, Rajkiya Engineering College Sonbhadra, U.P., India
  3. Department of Electrical/Electronics and Instrumentation Engineering, Institute of Chemical Technology, Indianoil Odisha Campus, Bhubaneswar751013, India
  4. Faculty of Control, Robotics and Electrical Engineering, Poznan University of Technology, Piotrowo 3A, 60-965 Poznan, Poland
  5. Ingenium Research Group, University of Castilla-La Mancha, Spain
Download PDF Download RIS Download Bibtex

Abstract

In this paper, a new Multi-Layer Perceptron Neural Network (MLP NN) classifier is proposed for classifying sonar targets and non-targets from the acoustic backscattered signals. Besides the capabilities of MLP NNs, it uses Back Propagation (BP) and Gradient Descent (GD) for training; therefore, MLP NNs face with not only impertinent classification accuracy but also getting stuck in local minima as well as lowconvergence speed. To lift defections, this study uses Adaptive Best Mass Gravitational Search Algorithm (ABGSA) to train MLP NN. This algorithm develops marginal disadvantage of the GSA using the bestcollected masses within iterations and expediting exploitation phase. To test the proposed classifier, this algorithm along with the GSA, GD, GA, PSO and compound method (PSOGSA) via three datasets in various dimensions will be assessed. Assessed metrics include convergence speed, fail probability in local minimum and classification accuracy. Finally, as a practical application assumed network classifies sonar dataset. This dataset consists of the backscattered echoes from six different objects: four targets and two non-targets. Results indicate that the new classifier proposes better output in terms of aforementioned criteria than whole proposed benchmarks.

Go to article

Authors and Affiliations

Mohammad Reza Mosavi
Mohammad Khishe
Mohammad Jafar Naseri
Gholam Reza Parvizi
Mehdi Ayat
Download PDF Download RIS Download Bibtex

Abstract

Due to its unique features, the metal foam is considered as one of the newest acoustic absorbents. It is a navel approach determining the structural properties of sound absorbent to predict its acoustical behavior. Unfortunately, direct measurements of these parameters are often difficult. Currently, there have been acoustic models showing the relationship between absorbent morphology and sound absorption coefficient (SAC). By optimizing the effective parameters on the SAC, the maximum SAC at each frequency can be obtained. In this study, using the Benchmarking method, the model presented by Lu was validated in MATLAB coding software. Then, the local search algorithm (LSA) method was used to optimize the metal foam morphology parameters. The optimized parameters had three factors, including porosity, pore size, and metal foam pore opening size. The optimization was applied to a broad band of frequency ranging from 500 to 8000 Hz. The predicted values were in accordance with benchmark data resulted from Lu model. The optimal range of the parameters including porosity of 50 to 95%, pore size of 0.09 to 4.55 mm, and pore opening size of 0.06 to 0.4 mm were applied to obtain the highest SAC for the frequency range of 500 to 800 Hz. The optimal amount of pore opening size was 0.1 mm in most frequencies to have the highest SAC. It was concluded that the proposed method of the LSA could optimize the parameters affecting the SAC according to the Lu model. The presented method can be a reliable guide for optimizing microstructure parameters of metal foam to increase the SAC at any frequency and can be used to make optimized metal foam.

Go to article

Authors and Affiliations

Mohammad Javad Jafari
Ali Khavanin
Touraj Ebadzadeh
Mahmood Fazlali
Mohsen Niknam Sharak
Rohollah Fallah Madvari
Download PDF Download RIS Download Bibtex

Abstract

The article discusses an example of the use of graph search algorithms with trace of water analysis and aggregation of failures in the occurrence of a large number of failures in the Water Supply System (WSS). In the event of a catastrophic situation, based on the Water Distribution System (WDS) network model, information about detected failures, the condition and location of valves, the number of repair teams, criticality analysis, the coefficient of prioritization of individual network elements, and selected objective function, the algorithm proposes the order of repairing the failures should be analyzed. The approach proposed by the authors of the article assumes the selection of the following objective function: minimizing the time of lack of access to drinking water (with or without prioritization) and minimizing failure repair time (with or without failure aggregation). The algorithm was tested on three different water networks (small, medium, and large numbers of nodes) and three different scenarios (different numbers of failures and valves in the water network) for each selected water network. The results were compared to a valve designation approach for closure using an adjacency matrix and a Strategic Valve Management Model (SVMM).
Go to article

Authors and Affiliations

Ariel Antonowicz
1
ORCID: ORCID
Andrzej Urbaniak
1

  1. Institute of Computing Science, Poznan University of Technology, ul. Piotrowo 2, 60-965 Poznan, Poland
Download PDF Download RIS Download Bibtex

Abstract

The paper presents a novel hybrid cuckoo search (CS) algorithm for the optimization of the line-start permanent magnet synchronous motor (LSPMSM). The hybrid optimization algorithm developed is a merger of the heuristic algorithm with the deterministic Hooke–Jeeves method. The hybrid optimization procedure developed was tested on analytical benchmark functions and the results were compared with the classical cuckoo search algorithm, genetic algorithm, particle swarm algorithm and bat algorithm. The optimization script containing a hybrid algorithm was developed in Delphi Tiburón. The results presented show that the modified method is characterized by better accuracy. The optimization procedure developed is related to a mathematical model of the LSPMSM. The multi-objective compromise function was applied as an optimality criterion. Selected results were presented and discussed.
Go to article

Authors and Affiliations

Łukasz Knypiński
1
ORCID: ORCID

  1. Poznan University of Technology, Institute of Electrical Engineering and Electronics, Piotrowo 3a, 60-965 Poznan, Poland
Download PDF Download RIS Download Bibtex

Abstract

In this paper, a new application of the Numerical Assembly Technique is presented for the balancing of linear elastic rotor-bearing systems with a stepped shaft and arbitrarily distributed mass unbalance. The method improves existing balancing techniques by combining the advantages of modal balancing with the fast calculation of an efficient numerical method. The rotating stepped circular shaft is modelled according to the Rayleigh beam theory. The Numerical Assembly Technique is used to calculate the steady-state harmonic response, eigenvalues and the associated mode shapes of the rotor. The displacements of a simulation are compared to measured displacements of the rotor-bearing system to calculate the generalized unbalance for each eigenvalue. The generalized unbalances are modified according to modal theory to calculate orthogonal correction masses. In this manner, a rotor-bearing system is balanced using a single measurement of the displacement at one position on the rotor for every critical speed. Three numerical examples are used to show the accuracy and the balancing success of the proposed method.
Go to article

Bibliography

  1.  J. Tessarzik, Flexible rotor balancing by the exact point speed influence coefficient method. Latham: Mechanical Technology Incorporated, 1972.
  2.  P. Gnielka, “Modal balancing of flexible rotors without test runs: An experimental investigation,” Journal of Vibrations, vol. 90, no. 2, pp. 152–170, 1982.
  3.  K. Federn, “Grundlagen einer systematischen Schwingungsentstörung wellenelastischer Rotoren,” VDI Bericht, vol. 24, pp.  9‒25, 1957.
  4.  A. G. Parkinson and R. E. D. Bishop, “Residual vibration in modal balancing,” Journal of Mechanical Engineering Science, vol. 7, pp. 33–39, 1965.
  5.  W. Kellenberger, “Das Wuchten elastischer Rotoren auf zwei allgemeinelastischen Lagern,” Brown Boveri Mitteilungen, vol. 54, pp. 603– 617, 1967.
  6.  A.-C. Lee, Y.-P. Shih, and Y. Kang, “The analysis of linear rotor bearing systems: A general Transfer Matrix Method,” Journal of Vibration and Accoustics, vol. 115, no. 4, pp. 490–497, 1993.
  7.  J.-S. Wu and H. M. Chou, “A new approach for determining the natural frequency of mode shapes of a uniform beam carrying any number of sprung masses,” Journal of Sound and Vibration, vol.  220, no. 3, pp. 451–468, 1999.
  8.  J.-S. Wu, F.-T. Lin, and H.-J. Shaw, “Analytical solution for whirling speeds and mode shapes of a distributed-mass shaft with arbitrary rigid disks,” Journal of Applied Mechanics, vol. 81, no. 3, pp. 034 503–1–034 503–10, 2014.
  9.  M. Klanner, M.S. Prem, and K. Ellermann, “Steady-state harmonic vibrations of a linear rotor- bearing system with a discontinuous shaft and arbitrarily distributed mass unbalance,” in Proceedings of ISMA2020 International Conference on Noise and Vibration Engineering and USD2020 International Conference on Uncertainty in Structural Dynamics, 2020, pp. 1257–1272.
  10.  M. Klanner and K. Ellermann, “Steady-state linear harmonic vibrations of multiple-stepped Euler-Bernoulli beams under arbitrarily distributed loads carrying any number of concentrated elements,” Applied and Computational Mechanics, vol. 14, no. 1, pp. 31–50, 2019.
  11.  M.B. Deepthikumar, A.S. Sekhar, and M.R. Srikanthan, “Modal balancing of flexible rotors with bow and distributed unbalance,” Journal of Sound and Vibration, vol. 332, pp. 6216‒6233, 2013.
  12.  O.A. Bauchau and J.I. Craig, Structural Analysis – With Applications to Aerospace Structures. Heidelberg: Springer Verlag, 2009.
  13.  R.E.D. Bishop and A.G. Parkinson, “On the isolation of modes in balancing of flexible shafts,” Proc. Inst. Mech. Eng., vol. 117, pp. 407– 426, 1963.
  14.  X. Rui, G. Wang, Y. Lu, and L. Yunm, “Transfer Matrix Method for linear multibody systems,” Multibody Syst. Dyn., vol.  19, pp. 179–207, 2008.
  15.  I.N. Bronstein, K.A. Semendjajew, and E. Zeidler, Taschenbuch der Mathematik. Stuttgard: Teubner, 1996.
  16.  D. Bestle, L. Abbas, and X. Rui, “Recursive eigenvalue search algorithm for transfer matrix method of linear flexible multibody systems,” Multibody Syst. Dyn., vol. 32, pp. 429–444, 2013.
  17.  B. Xu and L. Qu, “A new practical modal method for rotor balancing,” Proc. Inst. Mech. Eng. Part C J. Mech. Eng. Sci., vol. 215, pp.  179–190, 2001.
  18.  J. Tessarzik, Flexible rotor balancing by the influence coefficient method. Part 1: Evaluation of the exact point speed and least squares procedure. Latham: Mechanical Technology Incorporated, 1972.
Go to article

Authors and Affiliations

Georg Quinz
1
Marcel S. Prem
1
Michael Klanner
1
ORCID: ORCID
Katrin Ellermann
1

  1. Graz University of Technology, Institute of Mechanics, Kopernikusgasse 24/IV, 8010 Graz, Austria
Download PDF Download RIS Download Bibtex

Abstract

One of the most important aims of the sizing and allocation of distributed generators (DGs) in power systems is to achieve the highest feasible efficiency and performance by using the least number of DGs. Considering the use of two DGs in comparison to a single DG significantly increases the degree of freedom in designing the power system. In this paper, the optimal placement and sizing of two DGs in the standard IEEE 33-bus network have been investigated with three objective functions which are the reduction of network losses, the improvement of voltage profiles, and cost reduction. In this way, by using the backward-forward load distribution, the load distribution is performed on the 33-bus network with the power summation method to obtain the total system losses and the average bus voltage. Then, using the iterative search algorithm and considering problem constraints, placement and sizing are done for two DGs to obtain all the possible answers and next, among these answers three answers are extracted as the best answers through three methods of fuzzy logic, the weighted sum, and the shortest distance from the origin. Also, using the multi-objective non-dominated sorting genetic algorithm II (NSGA-II) and setting the algorithm parameters, thirty-six Pareto fronts are obtained and from each Pareto front, with the help of three methods of fuzzy logic, weighted sum, and the shortest distance from the origin, three answers are extracted as the best answers. Finally, the answer which shows the least difference among the responses of the iterative search algorithm is selected as the best answer. The simulation results verify the performance and efficiency of the proposed method.
Go to article

Authors and Affiliations

Hossein Ali Khoshayand
1
ORCID: ORCID
Naruemon Wattanapongsakorn
2
ORCID: ORCID
Mehdi Mahdavian
1
ORCID: ORCID
Ehsan Ganji
1
ORCID: ORCID

  1. Department of Electrical Engineering, Naein Branch, Islamic Azad University, Iran
  2. Department of Computer Engineering, King Mongkut’s University of Technology, Thonburi, 126 Prachautid Road, Bangmod, Bangkok 10140, Thailand

This page uses 'cookies'. Learn more