1,721,044 research outputs found
Force measurement device for controlling the position of an implement for towing by an agricultural machine
No full textA force measuring device for an implement for towing an agricultural machine comprising at least one connection arm between the implement and a flexure bar mounted on said agricultural machine, at least one lever connecting the arm to a control system, wherein said control system comprises an electrical circuit arranged to control the movement of the lever by means of a mechanical and/or hydraulic member, the electrical circuit comprising at least one resistive element fixed to a portion of the flexure bar, the resistive element being constructed of a material the resistance of which is proportional to the deformation which the element undergoes when in use
Localized states in different samples of beta-rhombohedral boron
No full textThe activation energy and relative concentration of localized states in beta-rhombohedral Boron obtained from several sources were studied by transient photoconductivity, space-charge-limited currents, thermally stimulated currents, and thermally stimulated depolarization currents. Activation energies for electron traps are 0.25 and 0.44 eV, and for hole traps, the activation energies are 0.23 and 0.36 eV. The differing location and density of localized states suggests that they are extrinsic in nature
Characterization of pyrolytic boron films
No full textThe transport mechanisms of pyrolytic B films were elucidated in order to study the characteristics of boron thermistors. Boron films were deposited thermal decomposition of BCl3 and H2 onto Mo (wires or sheets) of insulating (quartz) substrates. Electrical properties were studied for films in the thermistor structure with a layer bonded between two Mo crossed wires that formed electrical contacts, or films on quartz. The electrical conduction of the pyrolytic films was 7 × 10-5-10-6 Ohm-1 cm-1. An equation for the linear temperature dependence of the electrical conductivity is given for the temperature range 60-800 K. The thermoelectric power of the pyrolytic boron film was positive in the order 100 μV K-1 at 300 K. No appreciable photoconductiviy was observed. The results suggest that thermally activated hopping is the dominant transport mechanism in pyrolyic boron film. This film is superior to the crystalline or amorphous forms for the thermistor preparation
Thick film tecknology
No full textThis paper outlines the continuous progress of thick-film technology in providing a valuable means for the manufacture of solid-state sensors in three major areas of applications: hybrid circuits for signal processing, creation of structures upon which sensing materials can be added to provide new forms of sensors and thick-film materials able to offer suitable transducing properties. It is stressed here that while the technology proceeds apace, the material science of thick-film sensors requires greater research efforts
Other sensors, actuators and ancillary parts for measuring systems.
No full textA review, with 20 references. Previous sections in the book considered the major areas where thick film technology and materials were systematically studied for sensors applications. However a variety of minor themes (of interest for control systems and instrumentation) only marginally addressed, deserves a mention. Also thick-film components can play a significant role in sensors and actuators, even if they can not be defined as sensing elements. Examples of these matter are presented
Thermoelectric power in crystalline boron
No full textThe thermoelecric power of mono-crystalline beta-boron (purity >99.9995%, room-temperature resistivity 5 × MegaOhm cm), measured in the dark, increased from 305 to a maximum of 700 μV/K, and then fell to 650 μV/K, respectively, at T = 190, 345, and 435 K. The observed temperature dependence explained assuming two components in the boron conductivity: a p-type conduction in the valence band, and an n-type conduction of electrons hopping in an impurity band
Development and the implementation of high-temperature reliable heaters in plasma spray technology
No full textMany problems have been encountered during development of reliable high-temperature heaters by means of atmospheric plasma spray and procedures commonly adopted in thermal spray technology, especialy due to poor steel substrate corrosion resistance, notably affected by grit-blasting operations, but also deriving from contamination of insulating layers, dielectric arcs, and failures due to hot spots in the heating elements. While seeking the origin of these problems, a close scrutiny of every single step of the preparation process and analyses of the coatings were carried out using laser confocal scanning microscopy, optical and electronic microscopy, fluorescence analysis, X-ray diffraction, and ancillary techniques. The electrical properties of both alumina layers and metal strips prepared with Ni, NiCr, NiAl commercial powders for the heating elements were studied and cross-related to the failures in the heaters. The article reports the main results of these investigations, delineates the innovations introduced to overcome or circumvent the problems, and underlines the distinct characteristics of new heaters, whose reliability has been proven up to now with temperatures of up to 600 °C in air
Deep traps in Beta-rhombohedral boron
No full textThe activation energy of deep traps was studied in a series of beta-rhombohedral boron samples taken from different companies and labs. The presence of deep traps in some samples induces polarization effects in transient photoconductivity experiments. The activation energy of these deep traps, determined by thermally stimulated depolarization-current measurements, is (0.45 ± 0.03) eV in agreement with results previously obtained by other authors using various techniques. The apparent absence of these deep traps in some samples shows that they are not associated. with the complex lattice structure of beta-rhombohedral boron, as suggested by some authors
Method for producing heated components for injection moulding apparatus and heating equipment in general” US 7,322,099 , Jan. 29, 2008
No full textA method for producing components for injection moulding comprising a body made of thermally conducting material with expansion coefficient matching that of the insulating layers and provided with a passage for the material to be injected. At least one strip of electrically conducting material with high change of resistance with temperature, forming a heating resistor or inductor is applied on a electrically insulating base layer previously directly applied on the body. At least one final insulating layer with low thermal emissivity is then applied to optimise electrical efficiency. The method utilises thermal spray techniques and can be applied also for production of other heating equipmen
Thick film resistors
No full textA review with 42 references. Thick film resistors (TFRs) play a relevant role in sensor technology. They are essential elements of thick-film hybrid circuits for sensor signal conditioning as well as sensing elements. The general features of TFRs are given in terms of composition, microstructure and characteristics of performance
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