Tight-frame-like Sparse Recovery Using Non-tight Sensing Matrices

The choice of the sensing matrix is crucial in compressed sensing (CS). Gaussian sensing matrices possess the desirable restricted isometry property (RIP), which is crucial for providing performance guarantees on sparse recovery. Further, sensing matrices that constitute a Parseval tight frame result in minimum mean-squared-error (MSE) reconstruction given oracle knowledge of the support of the sparse vector. However, if the sensing matrix is not tight, could one achieve the reconstruction performance assured by a tight frame by suitably designing the reconstruction strategy? This is the key question that we address in this paper. We develop a novel formulation that relies on a generalized l2-norm-based data-fidelity loss that tightens the sensing matrix, along with the standard l1 penalty for enforcing sparsity. The optimization is performed using proximal gradient method, resulting in the tight-frame iterative shrinkage thresholding algorithm (TF-ISTA). We show that the objective convergence of TF-ISTA is linear akin to that of ISTA. Incorporating Nesterovs momentum into TF-ISTA results in a faster variant, namely, TF-FISTA, whose objective convergence is quadratic, akin to that of FISTA. We provide performance guarantees on the l2-error for the proposed formulation. Experimental results show that the proposed algorithms offer superior sparse recovery performance and faster convergence. Proceeding further, we develop the network variants of TF-ISTA and TF-FISTA, wherein a convolutional neural network is used as the sparsifying operator. On the application front, we consider compressed sensing image recovery (CSIR). Experimental results on Set11, BSD68, Urban100, and DIV2K datasets show that the proposed models outperform state-of-the-art sparse recovery methods, with performance measured in terms of peak signal-to-noise ratio (PSNR) and structural similarity index metric (SSIM).Comment: 33 pages, 12 figure

Digitized Engineering Notebook

Digitized Engineering Notebook is a Web Based Application which is subject to the project status and their development reports and statistics. All the engineering students and professionals who work on the development of projects and mechanical applications maintain their notes and design process and other important attributes for the project. A General Engineering Notebook consists of Images, prototype sketches, development phases, data, and even text. These notebooks help the team members keep up with their work progress and make some important updates and notifications for themselves. However, this has a drop back by delaying the work and they take a lot of time in just making their notes because you have to keep up everything for every update instead of updating the previous day work. As of now we are developing a Web Based Application that will help all the users and project managers and team member connect to each other via portal and update their statistical reports and any other project updates. The major features about the project include Front End Interface where team members can login into their authorized accounts and make changes to the project. The team members can create new tables, add diagrams and even make changes to a table created by other user only if he is authorized. The portal is mainly used to communicate with each other, upload their reports, share the prototype designs in the form of image files, create appointments, reminders and deadlines for the specifies tasks. These are the important factors that are involved in the project above many other features. And all these features will be used by the user and team members with their level of authorization and information access. Above all the project manager and team leader will be having special access for their entry

<i>Ortho</i> C-H arylation of arenes at room temperature using visible light ruthenium C-H activation.

From Europe PMC via Jisc Publications RouterHistory: ppub 2020-04-01, epub 2020-04-07Publication status: PublishedA ruthenium-catalyzed ortho C-H arylation process is described using visible light. Using the readily available catalyst [RuCl2(p-cymene)]2, visible light irradiation was found to enable arylation of 2-aryl-pyridines at room temperature for a range of aryl bromides and iodides

Pd-catalyzed α-arylation of aldehydes

The transition metal-catalyzed asymmetric α-arylation of aldehydes is an highly challenging transformation in the synthetic chemistry. The α-arylated aldehydes are important structural motifs in many biologically and pharmaceutically active molecules. However, there are only few protocols available for the synthesis of α-arylated aldehydes. The main aim of this thesis is to find the suitable reaction conditions for the non-asymmetric and asymmetric α-arylation of aldehydes. In the first part of thesis, we have developed a [Pd(NHC)]-catalyzed intermolecular α-arylation of linear and α-branched aldehydes with aryl bromides. We have also reported the unusual α-arylative esterification of α-branched aldehydes and acylation of aryl bromide with linear aldehyde with same catalyst. In the second part of thesis, we describe the synthesis of novel atropoisomeric (P,N)-ligands and their application in the Pd-catalyzed asymmetric α-arylation of α-branched aldehydes. Under the optimized conditions, the enantio-enriched α-arylated aldehydes were obtained in good yields with excellent levels of enantioselectivities

Estudios experimentales mediante técnicas ópticas de las características de sprays para motores dual-fuel

This work presents two experimental studies for characterization of injection sprays using experimental techniques as the fundamental tools. The first study focuses on the detailed understanding of the mixing process and the factors controlling the characteristics of the spray when different blends of fuel are injected in an inert atmosphere at high pressure and temperature. The second part of the work focuses on the determination of the characteristics of the jets generated with different configurations of prototype injectors, which have been designed for diesel-natural gas dual fuel combustion engines.Este trabajo presenta dos estudios experimentales de caracterización de chorros de inyección utilizando técnicas experimentales como herramienta fundamental. El primer estudio se centra en la comprensión detallada de los procesos de formación de la mezcla y los factores que controlan las características del chorro cuando se inyectan mezclas de combustibles en distintas proporciones en una atmósfera inerte a elevada presión y temperatura. La segunda parte del trabajo se centra en la determinación de las características de los chorros generados con diferentes configuraciones de inyectores prototipo diseñados para motores de combustión dual diesel-gas natural.Nareddy, VR. (2017). Estudios experimentales mediante técnicas ópticas de las características de sprays para motores dual-fuel. http://hdl.handle.net/10251/85830TFG