221 research outputs found
Development of a prototype for submarine communications in shallow waters
The Telecommunications Marine Laboratory (TML) of the University of
Cádiz takes part in a research project to study the intertidal sediments of the Bay
of Cádiz. The collection of samples from the seabed and the transmission of data
to the surface are performed by a Mini Profiler with four channels (MP4), which is
supplied by UNISENSE. Each channel processes the samples collected by a single
sensor. For power, control, and data transmission, a special wiring that connects the
submerged subsystem with the surface subsystem is used. The tension transmitted
by the cable to the MP4 structure makes its handling and positioning under water
more difficult. This article explains the technological solution developed by the TML
to replace some wiring from the MP4. For the prototype, two underwater acoustic
modems have been used and an electronic system has been developed based on the
Arduino platform, in order to multiplex, digitize, and transmit the data collected by
the MP4 sensors, eliminating the need to use wiring. The submerged subsystem has
an autonomous power supply by a battery.Peer Reviewe
Single-Flux-Quantum Bipolar Digital-to-Analog Converter Comprising Polarity-Switchable Double-Flux-Quantum Amplifier
We present a single-flux-quantum (SFQ)-based digital-to-analog converter (DAC) generating bipolar output voltages, in which the key component is a polarity-switchable double-flux-quantum amplifier (PS-DFQA). The DAC comprised a dc/SFQ converter, an 8-bit variable pulse-number-multiplier (PNM), and a 8-fold PS-DFQA integrated on a single chip. SFQ pulse-frequency modulation was employed to realize variable output voltage amplitude, for which the multiplication factor of the variable-PNM was controlled by a commercial data generator situated at room temperature. The variable-PNM realized 8-bit resolution with a multiplication factor between 0 and 255. Bias currents fed to the 8-fold PS-DFQA were polarity-switched in synchronization with the digital code for the variable-PNM. The whole circuits including I/O elements were designed using SFQ cell libraries, and fabricated using a niobium integration process. Sinusoidal bipolar voltage waveform of 0.38 mVpp was demonstrated using a reference signal source of 43.94 MHz
The Dirac Quantum Automaton: a preview
Quantum Information and the new informational paradigm are entering the
domain of quantum field theory and gravity, suggesting the quantum automata
framework. The quantum automaton is the minimal-assumption extension to the
Planck and ultrarelativistic scales of quantum field theory. It can describe
localized states and measurements, which are unmanageable by quantum field
theory. The automaton theory is a very promising framework for quantum gravity,
since it is quantum ab-initio, with relativistic covariance as emergent and not
assumed a priori, it is free from all the problems arising from the continuum,
it doesn't suffer violations of causality, and has no divergences. It is the
natural scenario to accommodate the quantum holographic principle. Lorentz
covariance and all other symmetries are violated in the ultrarelativistic
Planckian regime, but are perfectly recovered at the Fermi-scale.
In the present report, after briefly reviewing the fundamental principles at
the basis of the quantum cellular automata extension of quantum field theory, I
will present a preview of recent results on the Fermi scale limit [1] and on
the Dirac automaton in two space-dimensions [2]. The automaton in three
dimensions is under way.Comment: Work presented at the conference "Quantum Theory: Reconsideration of
Foundations-6 on June 12th 2012 at Linnaeus University, Vaxjo, Sweden. [10
pages, 2 eps figures
ALL DIGITAL DESIGN AND IMPLEMENTAION OF PROPORTIONAL-INTEGRAL-DERIVATIVE (PID) CONTROLLER
Due to the prevalence of pulse encoders for system state information, an all-digital proportional-integral-derivative (ADPID) is proposed as an alternative to traditional analog and digital PID controllers. The basic concept of an ADPID stems from the use of pulse-width-modulation (PWM) control signals for continuous-time dynamical systems, in that the controllers proportional, integral and derivative actions are converted into pulses by means of standard up-down digital counters and other digital logic devices. An ADPID eliminates the need for analog-digital and digital-analog conversion, which can be costly and may introduce error and delay into the system. In the proposed ADPID, the unaltered output from a pulse encoder attached to the systems output can be interpreted directly. After defining a pulse train to represent the desired output of the encoder, an error signal is formed then processed by the ADPID. The resulting ADPID output or control signal is in PWM format, and can be fed directly into the target system without digital-to-analog conversion. In addition to proposing an architecture for the ADPID, rules are presented to enable control engineers to design ADPIDs for a variety of applications
Upper extremity kinetics during walker-assisted gait of knee joint stiffness simulation
Because of various inflammations and fractures of low limbs, the number of patients with knee joint stiffness is increasing. Walkers are commonly prescribed to improve these patients' stability and ambulatory ability. The evaluation on the assisted walking effect has become a hot problem, whose prerequisite is a comprehensive mechanical understanding of the upper extremity force. In order to study the upper extremity kinetics during walker-assisted gait of knee joint stiffness, this paper developed a new method to collect upper extremity kinetics data based on a special-designed walker dynamometer system. Handle reaction vector (HRV) data were collected from 15 healthy right-handed young subjects by simulation experiments for four knee joint stiffness modes. T test and support vector machine (SVM) were used to analyze these HRV data. The results indicated that knee joint stiffness had a great influence on the upper extremity force during the walker-assisted walking. The proposed method is hoped to beneficially influence walker-assisted gait retraining strategies for knee joint stiffness. © 2010 IEEE.published_or_final_versionThe 2010 IEEE International Conference on Virtual Environments Human-Computer Interfaces and Measurement Systems (VECIMS), Taranto, Apulia, Italy, 6-8 September 2010. In Proceedings of the IEEE-VECIMS, 2010, p. 1-
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