waseem abbas

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Computing Graph Descriptors on Edge Streams

ACM Transactions on Knowledge Discovery from Data

Feature extraction is an essential task in graph analytics. These feature vectors, called graph d... more Feature extraction is an essential task in graph analytics. These feature vectors, called graph descriptors, are used in downstream vector-space-based graph analysis models. This idea has proved fruitful in the past, with spectral-based graph descriptors providing state-of-the-art classification accuracy. However, known algorithms to compute meaningful descriptors do not scale to large graphs since: (1) they require storing the entire graph in memory, and (2) the end-user has no control over the algorithm’s runtime. In this article, we present streaming algorithms to approximately compute three different graph descriptors capturing the essential structure of graphs. Operating on edge streams allows us to avoid storing the entire graph in memory, and controlling the sample size enables us to keep the runtime of our algorithms within desired bounds. We demonstrate the efficacy of the proposed descriptors by analyzing the approximation error and classification accuracy. Our scalable al...

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Synthesis and characterizations of Al-Sm substituted Ba-Sr M-type hexagonal ferrite nanoparticles via sol-gel route

Ceramics International, 2018

In this work, the Al 3+-Sm 3+ substituted M-type Ba-Sr hexaferrites, having a composition of Ba 0... more In this work, the Al 3+-Sm 3+ substituted M-type Ba-Sr hexaferrites, having a composition of Ba 0.4 Sr 0.6 Al 0.4x Sm x Fe 11.60 O 19 (BSAMFO; Pure, 0.0 ≤ x ≤ 0.4) were synthesized using the sol-gel technique. To achieve the hexagonal phase, the optimum annealing temperature was measured by the TGA analysis. X-ray diffraction (XRD) was employed to identify the phase of magnetic powders (MPs). The XRD pattern reveals that the MPs with Al 3+ and Sm 3+ contents (for x ≤ 0.4) represent α-Fe 2 O 3 as a second phase and the MPs (with 0.1 ≤ x ≤ 0.4) show the presence of a small amount of FeSmO 3 phases. Fourier transform infrared spectroscopy (FTIR) and XRD examination clearly expose the different band modes in structure, formation and the compositions of the hexagonal structure, whereas scanning electron microscopy (SEM) was employed to examine the morphologies of the MPs. The hexagonal platelet-like shape with size 0.54-1.23 µm of MPs is observed by SEM images. The presence of ferrite elements is confirmed by energy dispersive spectrometer (EDS) analysis. The magnetic characteristics of MPs were analyzed by a physical property measurement system-vibrating sample magnetometer (PPMS-VSM). Results reveal that Al 3+-Sm 3+ substitutions modify the saturation magnetization (M s), a remanant magnetization (M r) and coercivity (H c). Additionally, the H c value decreased while M s and M r exhibited the monotonic behavior as the function of x. x Fe 12 0 19 by the ceramic method and achieved the magnetic properties at x = 0.25. Abbas et al., [17] investigated Pr 3+ ions substituted in Ba

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