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2 2021

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Optimized jk-nearest neighbor based online signature verification and evaluation of main parameters

Saleem Muhammad, Kovari Bence

Computer Science

2021

T. 22 (4)

539--551

In this paper, we propose an enhanced jk-nearest neighbor (jk-NN) algorithm for online signature verification. The effect of its main parameters is evaluated and used to build an optimized system. The results show that the jk-NN classifier improves the verification accuracy by 0.73–10% as compared to a traditional one-class k-NN classifier. The algorithm achieved reasonable accuracy for different databases: a 3.93% average error rate when using the SVC2004, 2.6% for the MCYT-100, 1.75% for the SigComp’11, and 6% for the SigComp’15 databases. These results followed a state-of-the-art accuracy evaluation where both forged and genuine signatures were used in the training phase. Another scenario is also presented in this paper by using an optimized jk-NN algorithm that uses specifically chosen parameters and a procedure to pick the optimal value for k using only the signer’s reference signatures to build a practical verification system for real-life scenarios where only these signatures are available. By applying the proposed algorithm, the average error rates that were achieved were 8% for SVC2004, 3.26% for MCYT-100, 13% for SigComp’15, and 2.22% for SigComp’11.

Atomic Ordering Behavior of CoTi Alloy with Addition of Transition Metals

Hussain Abid, Ziya Amer Bashir, Atiq Shabbar, Saleem Muhammad, Ullah Mahtab, Ahmad Sajjad, Ahmad Naseeb

Archives of Metallurgy and Materials

2021

Vol. 66, iss. 2

425--430

The statistical-thermodynamic theory of ordering and electronic theory of ordering in the pseudo-potential approximation was used to study the influence of ternary addition of some transition metals on the atomic ordering behavior of Co0.5(Ti1-xMx)0.5 alloys with M = Fe, Pt, re, V, Cr, Mn, Ni, Cu, Zn, Zr, Ag, Hf or Au up to a concentration of 1 at.%. The partial ordering energies, order-disorder phase transformation temperatures and partial short range order parameters have been calculated for these alloys. The analysis shows that the impurity elements in Co0.5(Ti1-xMx)0.5 alloys can be divided into two main groups on the basis of lattice site occupancy i.e. M = V, Cr, Mn, Cu, Zn, Zr, Ag, Hf and Au mainly substitute for Co sublattice sites whereas M = Fe, Ni, Pt or re mainly substitute for Ti sublattice sites. Further, the order-disorder transformation temperatures were found to either increase or remain nearly unchanged by the addition of ternary impurities in the CoTi alloy depending on the absolute value of the partial ordering energies. Alloys of Ti with V, Cr, mn, Cu, Zn, Zr, Ag, Hf or Au in place of Co and alloys of Co with Fe, Ni, Pt or Re in place of Ti can be predicted for future. The results of the present analysis are in good agreement with the available experimental data on these alloys.