Certifying the restricted isometry property is hard

This paper is concerned with an important matrix condition in compressed sensing known as the restricted isometry property (RIP). We demonstrate that testing whether a matrix satisfies RIP is NP-hard. As a consequence of our result, it is impossible to efficiently test for RIP provided P \neq NP

CASE STUDIES FROM DIFFERENT TYPES OF HEAT EXCHANGERS TO PLATE AND SHELL HEAT EXCHANGER: A REVIEW

A Plate and Shell Heat Exchanger (PSHE) is manufactured with round welded plates in its core. These plates are designed to withstand high pressures and temperatures. Failures in this kind of heat exchanger were registered in a short operating period. To obtain the failure modes present in this equipment and a theoretical framework concerning this field of study, a research methodology was proposed (Systematic Literature Review – SLR) and a theoretical survey was carried out focusing in the 316L stainless steel and titanium grade 1 for its use in the Brazilian offshore industry. Seeing that the whole PSHE structure is welded, it is necessary to account for the strain caused by severe expansion processes in heat exchanger joints. This regarding, the laser welding process was investigated because of its narrow melting zone. It is believed that it was possible to clarify which failure modes are related to corrosive processes or stress concentration highlighting the structural and mechanical characterization models employed. Considering that the research field is relatively new, it was feasible to establish a theoretical basis of solutions applicable to PSHE, such as the use of more recessive material, reduce the corrosiveness of the operating medium, and reduce external sources of tension. Also, new content was assembled to assess the future decision-making process, regarding the design or maintenance of welded plate exchangers

Normocalcemic versus Hypercalcemic Primary Hyperparathyroidism: More Stone than Bone?

Introduction. Normocalcemic primary hyperparathyroidism (NPHPT) is considered a variant of the more frequent form of the disease characterized by normal serum calcium levels with high PTH. The higher prevalence of renal stones in patients with HPTP and the well established association with bone disorders show the importance of studies on how to manage asymptomatic patients. Objective. To compare the clinical and laboratory data between the normocalcemic and mild hypercalcemic forms of PHPT. Methods. We retrospectively evaluated 70 patients with PHPT, 33 normocalcemic and 37 mild hypercalcemic. Results. The frequency of nephrolithiasis was 18.2% in normocalcemic patients and 18.9% in the hypercalcemic ones (P = 0.937). Fifteen percent of normocalcemic patients had a previous history of fractures compared to 10.8% of hypercalcemic patients, although there was no statistically significant difference (P = 0.726). Conclusion. Our data confirms a high prevalence of urolithiasis in normocalcemic primary hyperparathyroidism, but with the preservation of cortical bone. This finding supports the hypothesis that this disease is not an idle condition and needs treatment

Criação e manutenção de Digitonthophagus gazella em laboratório.

O objetivo deste trabalho foi estabelecer uma colônia de besouros para a distribuição entre os produtores rurais do Estado de Rondônia, visando o controle estratégico da mosca dos chifres

Arquitetura de copa em cajueiro anão precoce, através da poda de formação, e sua influência na produtividade das plantas.

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Structural integrity of polymeric components produced by additive manufacturing (Am)—polymer applications

Funding Information: Authors acknowledge Funda??o para a Ci?ncia e a Tecnologia (FCT-MCTES) for its financial support via the project UIDB/00667/2020 (UNIDEMI) and project UIDB/00285/2020 (CEMMPRE). Funding Information: Funding: Authors acknowledge Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via the project UIDB/00667/2020 (UNIDEMI) and project UIDB/00285/2020 (CEMMPRE). Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.In the work presented herein, the structural integrity of polymeric functional components made of Nylon-645 and Polylactic acid (PLA) produced by additive manufacturing (Fused Deposition Modelling, FDM) is studied. The PLA component under study was selected from the production line of a brewing company, and it was redesigned and analyzed using the Finite Element Method, 3D printed, and installed under real service. The results obtained indicated that, even though the durability of the 3D printed part was lower than the original, savings of about EUR 7000 a year could be achieved for the component studied. Moreover, it was shown that widespread use of AM with other specific PLA components could result in even more significant savings. Additionally, a metallic hanger (2700 kg/m3 ) from the cockpit of an airplane ATR 70 series 500 was successfully redesigned and additively manufactured in Nylon 645, resulting in a mass reduction of approximately 60% while maintaining its fit-for-purpose. Therefore, the components produced by FDM were used as fully functional components rather than prototype models, which is frequently stated as a major constraint of the FDM process.publishersversionpublishe

Observações preliminares sobre o parasitismo natural por Toxocara vitulorum em búfalos jovens em Rondônia, Brasil.

O objetivo deste trabalho foi averiguar a prevalência de Toxocara vitulorum no rebanho bubalino do Campo Experimental de Presidente Médici, da Embrapa Rondônia

Avaliação de práticas de manejo da cultura do cajueiro comum.

Apesar de se reconhecer que e possivel obter significativos aumentos de producao na cultura, com a aplicacao de fertilizantes, esta e uma pratica muito pouco utilizada pelos produtores. O reduzido numero de resultados experimentais, os custos dos fertilizantes e o elevado numero de plantas improdutivas sao os principais fatores que concorrem para a nao adocao do uso de fertilizantes na cultura.bitstream/CNPAT-2010/1841/1/Pa-008.pd

Cultivo de sapoti e sapota sob irrigação localizada no litoral cearense.

Este trabalho tem como objetivo observar a adaptação do sapotizeiro no litoral cearense e a viabilidade técnica do seu cultivo sob irrigação.bitstream/CNPAT-2010/11958/1/Ct-051.pd

Sistema de gestão de clientes: Manual do usuário.

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