Linearized ADMM and FAST nonlocal denoising for efficient plug-and-play restoration

In plug-and-play image restoration, the regularization is performed using powerful denoisers such as nonlocal means (NLM) or BM3D. This is done within the framework of alternating direction method of multipliers (ADMM), where the regularization step is formally replaced by an off-the-shelf denoiser. Each plug-and-play iteration involves the inversion of the forward model followed by a denoising step. In this paper, we present a couple of ideas for improving the efficiency of the inversion and denoising steps. First, we propose to use linearized ADMM, which generally allows us to perform the inversion at a lower cost than standard ADMM. Moreover, we can easily incorporate hard constraints into the optimization framework as a result. Second, we develop a fast algorithm for doubly stochastic NLM, originally proposed by Sreehari et al. (IEEE TCI, 2016), which is about 80� faster than brute-force computation. This particular denoiser can be expressed as the proximal map of a convex regularizer and, as a consequence, we can guarantee convergence for linearized plug-and-play ADMM. We demonstrate the effectiveness of our proposals for super-resolution and single-photon imaging. © 2018 IEEE

Effect of heavy ion irradiation on self-supported diamond sheets

The self-supported diamond sheets were deposited at various deposition pressure (Pd) using HFCVD technique. The sheets were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM). XRD shows the growth of cubic diamond. This is confirmed by Raman spectroscopy showing a sharp line at 1332 cm−1 in all the sheets. The sheets deposited at low pressures show clean sharp facets. The sheets were irradiated with high energy Au and Ag ions of varying energy and dose. The energy range was 100–120 MeV and the dose varied between 1×1012 and 3×1013 ions. Raman spectra showed the reduction in the intensity of diamond line (1332 cm−1) as well as non-diamond band at 1550 cm−1 after irradiation. SEM images of irradiated sheets show a phase transformation on the surface of the crystal. A photoluminescence (PL) signal is observed after the irradiation of the sheets at 2.634 eV.© Elsevie

Indolo[3,2-b]indole donor-based D--A dyes for DSCs: investigating the role of -spacers towards recombination

status: publishe

Aggregation induced light harvesting of molecularly engineered D-A-pi-A carbazole dyes for dye-sensitized solar cells

Novel class of metal free organic dyes (CCTh and CCBz) with D-A-pi-A configuration, having carbazole as donor and 3-cyanopyridine as auxiliary acceptor replacing conventional benzannulated heterocycles along with variable pi-linkers were synthesized and used in dye-sensitized solar cells (DSSCs). Both the dyes are having cyanoacrylic acid as the anchoring group with thiophene (CCTh) and phenylene (CCBz) as pi-linkers. The photophysical, electrochemical, theoretical and photovoltaic properties of the dyes were investigated in detail. The absorption spectra of dyes on TiO2 showed broader absorption band for CCTh in comparison to the solution spectra indicating aggregation in solid state. The aggregation studies in varied THF/water fraction indicates J-aggregation for both the dyes. CCTh with thiophene linker showed broader absorption compared to CCBz, and the photovoltaic performance recorded for CCTh directly indicates better light harvesting ability corresponding to the red shifted J-aggregated states. Hence, solar cells fabricated with CCTh gave a power conversion efficiency of 3.39% and CCBz delivered an efficiency of 2.03% under full sun condition. A detailed investigation of device dynamics have been carried out employing charge extraction (CE), intensity-modulated photovoltage spectroscopy (IMVS) and open-circuit voltage decay (OCVD) measurements

Efficiency and productivity in the Indian unorganized manufacturing sector: did reforms matter?

Total factor productivity, Efficiency, Unorganized manufacturing, Reforms, Indian states, D24, O47, R11,