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.

NARMAX Approach for the Identification of a Dielectric Electroactive Polymer Actuator

Jakub Bernat,Jakub Kołota,Paulina Superczy´nska 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.9

System identification is a field of control engineering that deals with the preparation of a mathematical description by recognizing the static and dynamic properties of automation systems. It becomes particularly important in the black-box approach, in which the modeling technique constructs a model using only the output data obtained from the system based on the known input signal. One of the most complete and powerful identification methodologies available today for the identification of nonlinear systems is the NARMAX approach. This paper presents and compares three methodologies used to approximate the unknown structure of a dielectric electroactive polymer actuator by applying one-step and multi-step prediction. The motivation of this study was to check the possibilities of the recent identification techniques on the object with complicated dynamics like DEAP actuators.

Multi Observer Structure for Rapid State Estimation in Linear Time Varying Systems

Jakub Bernat 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

A new method to design observers for linear time-varying systems is presented in this paper. The method begins by constructing two layers. The first layer is made up of multiple observers, while the second establishes a relationship between observers via a weighted estimation state. The primary challenge was to find a new feedback process that would determine the second layer weights. The multiple observers of the first layer were investigated to determine a general observation law. The resulting multilayer structure significantly improves the transient characteristics of the observation process, which leads to a more efficient control system.

Use of styrene as sole carbon source by the fungus Exophiala oligosperma: optimization and modeling of biodegradation, pathway elucidation, and cell membrane composition.

Rene, Eldon R,Bernat, Przemyslaw,Dlugo?ski, Jerzy,Veiga, Maria C,Kennes, Christian Humana Press 2012 Applied biochemistry and biotechnology Vol.168 No.6

<P>Biodegradation of styrene by Exophiala sp. was tested at different initial concentrations (19.3-170.6 mgl(-1)), pH (2.8-8.7), and temperatures (19.8-45.1 C), for 120 h according to a 2(3) full-factorial central composite design. The specific growth rate (SGR, per hour) and specific styrene utilization rate (SUR, milligrams of styrene per milligram of biomass per hour) values were used as the response variables for optimization purposes. The interactions between concentration and temperature (P=0.022), and pH and temperature (P=0.010) for SGR, and interactions between concentration and temperature (P=0.012) for SUR were found to be statistically significant. The optimal values for achieving high SGR (0.15 h(-1)) and SUR (0.3622 mg styrene mg(-1) biomass h(-1)) were calculated from the regression model equation. Those values are C(o)=89.1 mgl(-1), pH=5.4, and T=31.5 C for SGR and C(o)=69.2 mgl(-1), pH=5.5, and T=32.4 C for SUR. It was also observed that the Exophiala strain degrades styrene via phenylacetic acid, involving initial oxidation of the vinyl side chain. Besides, in the presence of styrene, changes in the fatty acids profile were also observed. It is hypothesized that an increasing amount of linoleic acid (18:2) may be involved in the protection of the fungus against toxic substrate.</P>

Loss of strength in asbestos-cement water pipes due to leaching

Lluís Gil,Marco A. Perez,Ernest Bernat,Juan J. Cruz 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.5

Asbestos-cement is a material with valuable strength and durability. It was extensively used for water distribution pipes across the world from the 1950s until the early 1980s. The network of pipes in this case study dates from the 1970s, and after more than 30 to 40 years of service, some pipes have been found to break under common service pressure with no apparent reason. A set of mechanical tests was performed including bending, compression, pressure and crushing tests. Microscopy analysis was also used to understand the material behaviour. Tests showed that there was a clear loss of strength in the pipes and that the safety factor was under the established threshold in most of the specimens. Microscopy results showed morphological damage to the pipes. The loss of strength was attributed to a leaching effect. Leaching damages the cement matrix and reduces the frictional interfacial shear stress.

Changes in the Ammonia-Oxidizing Bacteria Community in Response to Operational Parameters During the Treatment of Anaerobic Sludge Digester Supernatant

( Cydzik Kwiatkowska ),( Agnieszka ),( Magdalena Zielinska ),( Katarzyna Bernat ),( Dorota Kulikowska ),( Irena Wojnowska Baryla ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.7

The understanding of the relationship between ammoniaoxidizing bacteria (AOB) communities in activated sludge and the operational treatment parameters supports the control of the treatment of ammonia-rich wastewater. The modifications of treatment parameters by alteration of the number and length of aerobic and anaerobic stages in the sequencing batch reactor (SBR) working cycle may influence the efficiency of ammonium oxidation and induce changes in the AOB community. Therefore, in the research, the impact of an SBR cycle mode with alternating aeration/ mixing conditions (7 h/1 h vs. 4 h/5.5 h) and volumetric exchange rate (n) on AOB abundance and diversity in activated sludge during the treatment of anaerobic sludge digester supernatant at limited oxygen concentration in the aeration stage (0.7 mg O2/l) was assessed. AOB diversity expressed by the Shannon-Wiener index (H`) was determined by the cycle mode. At aeration/mixing stage lengths of 7 h/1 h, H` averaged 2.48±0.17, while at 4 h/ 5.5 h it was 2.35±0.16. At the given mode, AOB diversity decreased with increasing n. The cycle mode did not affect AOB abundance; however, a higher AOB abundance in activated sludge was promoted by decreasing the volumetric exchange rate. The sequences clustering with Nitrosospira sp. NpAV revealed the uniqueness of the AOB community and the simultaneously lower ability of adaptation of Nitrosospira sp. to the operational parameters applied in comparison with Nitrosomonas sp.

Loss of strength in asbestos-cement water pipes due to leaching

Gil, Lluis,Perez, Marco A.,Bernat, Ernest,Cruz, Juan J. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.5

Asbestos-cement is a material with valuable strength and durability. It was extensively used for water distribution pipes across the world from the 1950s until the early 1980s. The network of pipes in this case study dates from the 1970s, and after more than 30 to 40 years of service, some pipes have been found to break under common service pressure with no apparent reason. A set of mechanical tests was performed including bending, compression, pressure and crushing tests. Microscopy analysis was also used to understand the material behaviour. Tests showed that there was a clear loss of strength in the pipes and that the safety factor was under the established threshold in most of the specimens. Microscopy results showed morphological damage to the pipes. The loss of strength was attributed to a leaching effect. Leaching damages the cement matrix and reduces the frictional interfacial shear stress.

Effectiveness of a multimodal exercise rehabilitation program on walking capacity and functionality after a stroke

Montserrat Grau Pellicer,Andrés Chamarro Lusar,Josep Medina Casanovas,Bernat-Carles Serdà Ferrer 한국운동재활학회 2017 JER Vol.13 No.6

Cortically projecting basal forebrain parvalbumin neurons regulate cortical gamma band oscillations

Kim, Tae,Thankachan, Stephen,McKenna, James T.,McNally, James M.,Yang, Chun,Choi, Jee Hyun,Chen, Lichao,Kocsis, Bernat,Deisseroth, Karl,Strecker, Robert E.,Basheer, Radhika,Brown, Ritchie E.,McCarley, National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.11

<P><B>Significance</B></P><P>When we are awake, purposeful thinking and behavior require the synchronization of brain cells involved in different aspects of the same task. Cerebral cortex electrical oscillations in the gamma (30–80 Hz) range are particularly important in such synchronization. In this report we identify a particular subcortical cell type which has increased activity during waking and is involved in activating the cerebral cortex and generating gamma oscillations, enabling active cortical processing. Abnormalities of the brain mechanisms controlling gamma oscillations are involved in the disordered thinking typical of neuropsychiatric disorders such as schizophrenia. Thus, these findings may pave the way for targeted therapies to treat schizophrenia and other disorders involving abnormal cortical gamma oscillations.</P><P>Cortical gamma band oscillations (GBO, 30–80 Hz, typically ∼40 Hz) are involved in higher cognitive functions such as feature binding, attention, and working memory. GBO abnormalities are a feature of several neuropsychiatric disorders associated with dysfunction of cortical fast-spiking interneurons containing the calcium-binding protein parvalbumin (PV). GBO vary according to the state of arousal, are modulated by attention, and are correlated with conscious awareness. However, the subcortical cell types underlying the state-dependent control of GBO are not well understood. Here we tested the role of one cell type in the wakefulness-promoting basal forebrain (BF) region, cortically projecting GABAergic neurons containing PV, whose virally transduced fibers we found apposed cortical PV interneurons involved in generating GBO. Optogenetic stimulation of BF PV neurons in mice preferentially increased cortical GBO power by entraining a cortical oscillator with a resonant frequency of ∼40 Hz, as revealed by analysis of both rhythmic and nonrhythmic BF PV stimulation. Selective saporin lesions of BF cholinergic neurons did not alter the enhancement of cortical GBO power induced by BF PV stimulation. Importantly, bilateral optogenetic inhibition of BF PV neurons decreased the power of the 40-Hz auditory steady-state response, a read-out of the ability of the cortex to generate GBO used in clinical studies. Our results are surprising and novel in indicating that this presumptively inhibitory BF PV input controls cortical GBO, likely by synchronizing the activity of cortical PV interneurons. BF PV neurons may represent a previously unidentified therapeutic target to treat disorders involving abnormal GBO, such as schizophrenia.</P>