The structural performance of arches made of few vossoirs with dry-joints

Bernat-Maso, Ernest,Gil, Lluis,Marce-Nogue, Jordi Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.6

This work approaches the structural performance of masonry arches that have a small ratio between number of vossoirs and span length. The aim of this research is to compare and validate three different methods of analysis (funicular limit analysis F.L.A., kinematic limit analysis K.L.A. and plane stress Finite Element Analysis F.E.A.) with an experimental campaign. 18 failure tests with arches of different shapes and boundary conditions have been performed. The basic failure mechanism was the formation of enough hinges in the geometry. Nevertheless, in few cases, sliding between vossoirs also played a relevant influence. Moreover, few arches didn't reach the collapse. The FLA and KLA didn't find a solution close to the experimental values for some of the tests. The low number of vossoirs and joints become a drawback for an agreement between kinematic mechanism, equilibrium of forces and geometry constraints. FLA finds a lower bound whereas KLA finds an upper bound of the ultimate load of the arch. FEA is the most reliable and robust method and it can reproduce most of the mechanism and ultimate loads. However, special care is required in the definition of boundary conditions for FEA analysis. Scientific justification of the more suitability of numerical methods in front of classic methods at calculating arches with a few vossoirs is the main original contribution of the paper.

The structural performance of arches made of few vossoirs with dry-joints

Ernest Bernat-Maso,Lluís Gil,Jordi Marcé-Nogué 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.6

This work approaches the structural performance of masonry arches that have a small ratio between number of vossoirs and span length. The aim of this research is to compare and validate three different methods of analysis (funicular limit analysis F.L.A., kinematic limit analysis K.L.A. and plane stress Finite Element Analysis F.E.A.) with an experimental campaign. 18 failure tests with arches of different shapes and boundary conditions have been performed. The basic failure mechanism was the formation of enough hinges in the geometry. Nevertheless, in few cases, sliding between vossoirs also played a relevant influence. Moreover, few arches didn’t reach the collapse. The FLA and KLA didn't find a solution close to the experimental values for some of the tests. The low number of vossoirs and joints become a drawback for an agreement between kinematic mechanism, equilibrium of forces and geometry constraints. FLA finds a lower bound whereas KLA finds an upper bound of the ultimate load of the arch. FEA is the most reliable and robust method and it can reproduce most of the mechanism and ultimate loads. However, special care is required in the definition of boundary conditions for FEA analysis. Scientific justification of the more suitability of numerical methods in front of classic methods at calculating arches with a few vossoirs is the main original contribution of the paper.

Wireless Powered Communication Networks: Research Directions and Technological Approaches

Niyato, Dusit,Kim, Dong In,Maso, Marco,Han, Zhu IEEE 2017 IEEE wireless communications Vol.24 No.6

<P>Current wireless and cellular networks are destined to undergo a significant change in the transition to the next generation of network technology. The so called wireless powered communication network (WPCN) has been recently emerging as a promising candidate for achieving the target performance of future networks. According to this paradigm, nodes in a WPCN can be equipped with hardware capable of harvesting energy from wireless signals, that is, their battery can be ubiquitously replenished without physical connections. Recent technological advances in the field of wireless power harvesting and transfer are providing strong evidence of the feasibility of this vision, especially for low-power devices. The future deployment of WPCN is more and more concretely foreseen. The aim of this article is therefore to provide a comprehensive review of the basics and backgrounds of WPCN, current major developments, and open research issues. In particular, we first give an overview of WPCN and its structure. We then present three major advanced approaches whose adoption could increase the performance of future WPCN: backscatter communications with energy harvesting; duty-cycle based energy management; and transceiver design for self-sustainable communications. We discuss implementation perspectives and tools for WPCN. Finally, we outline open research problems for WPCN.</P>

Test of Special Relativity Using a Fiber Network of Optical Clocks

Delva, P.,Lodewyck, J.,Bilicki, S.,Bookjans, E.,Vallet, G.,Le Targat, R.,Pottie, P.-E.,Guerlin, C.,Meynadier, F.,Le Poncin-Lafitte, C.,Lopez, O.,Amy-Klein, A.,Lee, W.-K.,Quintin, N.,Lisdat, C.,Al-Maso American Physical Society 2017 Physical Review Letters Vol.118 No.22

<P>Phase compensated optical fiber links enable high accuracy atomic clocks separated by thousands of kilometers to be compared with unprecedented statistical resolution. By searching for a daily variation of the frequency difference between four strontium optical lattice clocks in different locations throughout Europe connected by such links, we improve upon previous tests of time dilation predicted by special relativity. We obtain a constraint on the Robertson-Mansouri-Sexl parameter |alpha| <= 1.1 x 10(-8), quantifying a violation of time dilation, thus improving by a factor of around 2 the best known constraint obtained with Ives-Stilwell type experiments, and by 2 orders of magnitude the best constraint obtained by comparing atomic clocks. This work is the first of a new generation of tests of fundamental physics using optical clocks and fiber links. As clocks improve, and as fiber links are routinely operated, we expect that the tests initiated in this Letter will improve by orders of magnitude in the near future.</P>

Fertilizing capacity of cryopreserved sperm of Chirostoma jordani (Woolman, 1894)

Bustamante-González Jesús Dámaso,Gutiérrez-Díaz Dulce Leticia,Baca-Alejo Judith Sarai,Figueroa-Lucero Gerardo,Arenas-Ríos Edith,Hernández-Rubio María Cecilia,Ávalos-Rodríguez Alejandro 한국수산과학회 2024 Fisheries and Aquatic Sciences Vol.27 No.5

The genus Chirostoma is endemic from the Mesa Central of Mexico. It is conformed of 18 species and six subspecies. Five species are in some category of risk, because of this, Chirostoma jordani is an excellent model species to implement biotechnologies like gametes cryopreservation. Aim of present study was to evaluate fertilizing capacity of cryopreserved C. jordani sperm, as alternative to conservation and assisted reproduction in this specie and genus. Males and females were collected from wild Atlangatepec dam stock, Tlaxcala State, Mexico. Seminal quality was evaluated in fresh and cryopreserved semen with three cryoprotective agents (CPAs): 10% dimethyl sulfoxide (DMSO), 10% methanol (MeOH), 14% ethylene glycol (EG) and it was determined its post-thaw fertilizing capacity. Sperm motility percentage decreased during cryopreservation process (p < 0.05). There were not significant differences in post-thaw motility percentage between EG (53.5 ± 1.9%) and MeOH (53.3 ± 1.3%), but DMSO (50.3 ± 0.5%) was significantly different (p < 0.05). Results showed that 0.2 μL fresh semen were enough to fertilize 100% oocytes (n = 60). 10 μL DMSO and 5 μL MeOH and EG cryopreserved semen were necessary to fertilize oocytes 100% (n = 60) (p < 0.05). Cryopreservation and fertilization protocol for C. jordani sperm was efficient and it could be used for its assisted reproduction.

Blastocystis species and Gastrointestinal Symptoms in Peruvian Adults Attended in a Public Hospital

Robles-Cabrera Mayra Ximena,Maguiña Jorge L.,Gonzales-Huerta Luis,Panduro-Correa Vicky,Dámaso-Mata Bernardo,Pecho-Silva Samuel,Navarro-Solsol Ana Claudia,Rabaan Ali A.,Rodríguez-Morales Alfonso J.,Art 대한감염학회 2021 Infection and Chemotherapy Vol.53 No.2

The objective of this study was to evaluate the role of Blastocystis sp. in gastrointestinal symptoms reported by adult patients in a Peruvian hospital. A case-control 3:1 study was performed at the outpatient clinic. Direct stool examinations were done. One hundred sixty patients were included, 40 cases and 120 controls. Positivity to Blastocystis sp. was associated with dyspepsia (P <0.001), bloating (P <0.001) and abdominal pain (P = 0.03) in patients attending our hospital outpatient clinic.