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Analog Signal Conditioning in Instrumentation
Published in Robert B. Northrop, Introduction to Instrumentation and Measurements, 2018
DAs are widely used as input stages in a wide variety of amplifier types including OAs, analog comparators, analog multipliers, IAs, oscilloscope vertical and horizontal amplifiers, and certain specialized ICs. There are two important reasons for their wide use in signal-conditioning system designs: The first and foremost is the ability of the DA to respond to the difference in the input signals (Vi – V′i) and to discriminate against noise or interference common to both inputs. Such a common-mode (CM) input voltage that is desired to be eliminated is often a DC level, hum, or other coherent interference. Another reason for using a DA headstage is that it inherently discriminates against changes in the amplifier’s DC power supply voltages.
Storage Consolidation
Published in Hubbert Smith, Data Center Storage, 2016
Direct attached storage (DAS) means one server, directly attached to storage. For one server or a couple of servers, direct attached storage is perfectly reasonable and useful means to deploy storage attached to a server. There are several key drawbacks of DAS as compared to SAN (storage area network) systems: Over-provisioning (a fancy term for when people buy more than they need)Reliability risk, server down time: when the server is down, the data is unavailable until the server is back on lineStorage manageabilitySprawl, hardware spares, powerBackup inefficiencies
Cost-effective measurement equipment and data analysis tool for structural health monitoring. Case study: Metro railway bridge
Published in Joan-Ramon Casas, Dan M. Frangopol, Jose Turmo, Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability, 2022
P.L. Sierra, R.A. Chacón, X. Martinez
In SHM it is essential to have proper instrumentation with the necessary data acquisition frequency and resolution to asses the structural condition. The set of instruments used to measure a certain physical quantity is called measuring equipment, and consists of: transducers, and Data Acquisition System (DAS). Transducers convert the physical quantity to be measured into another signal, commonly electrical voltage differences. The DAS includes the signal processing, conversion to storable digital data and storage, transmission and/or post processing of that data.
iSDS: a self-configurable software-defined storage system for enterprise
Published in Enterprise Information Systems, 2018
Wen-Shyen Eric Chen, Chun-Fang Huang, Ming-Jen Huang
In additional to functional features, non-functional characteristics are another important goals that should be achieved by DAS. DAS focuses on three characteristics: fault tolerant, scalable and speedy. To achieve fault tolerance, the actor model is adopted. The actor model is a mathematical model of concurrent data processing (Hewitt 1977; Baker and Hewitt 1977). Under the actor model, an actor is the basic unit of building a software system. There are no data shared among the actors. Instead, the actors communicate by sending messages to and receiving messages from an internal messaging system. Therefore, when an actor is crashed, the actor can be restarted. It then rebuilds its state by receiving messages from the messaging system. Otherwise, by combing finite state machines (FSM) with the actor model, it is easier to model and implement the parallel processing of software by the FSM-based actors that transit to different states upon receiving messages (Liu and Lee 2002, Haller 2012).