A inteligibilidade da palavra em igrejas católicas, através de análises de carácter objectivo e subjectivo
Lencastre, Margarida Maria Mendes de Freitas de Queiroz e
1988-01-01
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4 records were found.
A new type of seismic network is in development that takes advantage of community volunteers to install low-cost accelerometers
in houses and buildings. The Community Seismic Network and Quake-Catcher Network are examples of
this, in which observational-based structural monitoring is carried out using records from one to tens of stations in a single
building. We have deployed about one hundred accelerometers in a number of buildings ranging between five and 23
stories in the Los Angeles region. In addition to a USB-connected device which connects to the host’s computer, we
have developed a stand-alone sensor-plug-computer device that directly connects to the internet via Ethernet or wifi. In
the case of the Community Seismic Network, the sensors report both continuous data and anomalies in local acceleration
to a cloud computing...
The recent years have witnessed an increasing interest in using wireless structural monitoring as a low-cost alternative to tethered monitoring systems. Previous work considered wireless sensors strictly as passive elements in the monitoring system, responsible only for collection of response measurements. This paper explores expansion of the wireless structural monitoring paradigm by including actuation capabilities in the design of a wireless active sensing unit. To validate the performance of the prototype unit in structural health monitoring applications, an aluminum plate monitored by piezoelectric active sensors is used. Piezoelectric actuators mounted to the surface of the plate are commanded by the wireless active sensing unit to excite and record the element. System identification models are then used to model the linear relat...
As researchers continue to explore wireless sensors for use in structural monitoring systems, validation of field performance must be done using actual civil structures. In this study, a network of low-cost wireless sensors was installed in the Geumdang Bridge, Korea to monitor the bridge response to truck loading. Such installations allow researchers to quantify the accuracy and robustness of wireless monitoring systems within the complex environment encountered in the field. In total, 14 wireless sensors were installed in the concrete box girder span of the Geumdang Bridge to record acceleration responses to forced vibrations introduced by a calibrated truck. In order to enhance the resolution of the capacitive accelerometers interfaced to the wireless sensors, a signal conditioning circuit that amplifies and filters low-level accele...
A low-cost wireless sensing unit is designed and fabricated for deployment as the building block of wireless structural health monitoring systems. Finite operational lives of portable power supplies, such as batteries, necessitate optimization of the wireless sensing unit design to attain overall energy efficiency. This is in conflict with the need for wireless radios that have far-reaching communication ranges that require significant amounts of power. As a result, a penalty is incurred by transmitting raw time-history records using scarce system resources such as battery power and bandwidth. Alternatively, a computational core that can accommodate local processing of data is designed and implemented in the wireless sensing unit. The role of the computational core is to perform interrogation tasks of collected raw time-history data an...
