arXiv subjects

Jun Shen

Publications and source records attributed to Jun Shen.

93 records · Page 6Linked to original sources

arXiv2015

A Formal Study on Backward Compatible Dynamic Software Updates

We study the dynamic software update problem for programs interacting with an environment that is not necessarily updated. We argue that such updates should be backward compatible. We propose a general definition of backward compatibility and cases of backward compatible program update. Based on our detailed study of real world program evolution, we propose classes of backward compatible update for interactive programs, which are included at an average of 32% of all studied program changes. The definitions of update classes are parameterized by our novel framework of program equivalence, which generalizes existing results on program equivalence to non-terminating executions. Our study of backward compatible updates is based on a typed extension of W language.

cs.SE↗

arXiv2011

Symmetric Group Testing and Superimposed Codes

We describe a generalization of the group testing problem termed symmetric group testing. Unlike in classical binary group testing, the roles played by the input symbols zero and one are "symmetric" while the outputs are drawn from a ternary alphabet. Using an information-theoretic approach, we derive sufficient and necessary conditions for the number of tests required for noise-free and noisy reconstructions. Furthermore, we extend the notion of disjunct (zero-false-drop) and separable (uniquely decipherable) codes to the case of symmetric group testing. For the new family of codes, we derive bounds on their size based on probabilistic methods, and provide construction methods based on coding theoretic ideas.

cs.IT↗

arXiv2008

Glassy magnetic behavior induced by $Cu^{2+}$ substitution in frustrated antiferromagnet $ZnCr_2O_4$

Structure and magnetic properties of the compounds $Zn_{1-x}Cu_xCr_2O_4$ (ZCCO) are investigated systematically. A structural phase transition from space-group symmetry $Fd3m$ to $I4_1/amd$ is observed in ZCCO. The critical value of the doping, $x$, appears at $0.58\sim 0.62$ through the appearance of a splitting of diffraction peaks at room temperature. Measurements of dc magnetization, ac susceptibility, memory effect and exchange bias-like (EB-like) effect have been performed to reveal the glassy magnetic behaviors of ZCCO. The system with $x\leqslant 0.50$ is suggested as a spin glass-like (SG-like) of magnetic characterization whereas doping values of $0.58\leqslant x\leqslant 0.90$ defines the system as a $"$cluster glass-like$"$ (CG-like) with unidirectional anisotropy. The Cu content suppresses the geometrical frustration of $ZnCr_2O_4$, which may correlate with the pinning effect of Cu sublattice on Cr sublattice to a preferential direction.

cond-mat.mtrl-sci↗