1,721,052 research outputs found
A low-cost instrument for the measurement of microwave resonances in quasi-spherical cavities
No full textIn reason of their extremely high accuracy in the determination of microwave resonance frequencies, quasi-spherical cavities are key instruments for pursuing a variety of metrological applications, spanning from the realization of primary temperature and pressure standards, to the determination of the electrical properties of pure gases and mixtures, including hygrometry. Also, the simple and rugged design and features of quasi-spherical resonators make them suitable for industrial applications in harsh environments over extended temperature and pressure ranges. In traditional laboratory practice, Vector Network Analyzers are needed to fully exploit the precision achievable in the measurement of the cavity eigenfrequencies. However, the cost and bulkiness of this instrumentation currently limit the applicability of these techniques and methods. This work presents and discusses the design of a low cost microwave instrument which may finally replace vector network analyzers while maintaining the precision and accuracy required for most application
In-Process Temperature Mapping System for Industrial Freeze Dryers
No full textThis paper describes a low-invasive temperature mapping system specially designed for vacuum and non accessibleenvironments, such as industrial freeze dryers. Thermal resistances tend to become quite hight in vacuum since convection is absent and even very small gaps have extremely conductive resistances. Temperature monitoring in the vacuum therefore requires sensors that do not inject power to minimize the self-heating and a special attention to the effect due to the involved thermal resistances. The proposed solution employs small autonomous measuring nodes that use a wireless connection to transmit the results and that are characterized to correct the thermal constant effect during temperature changes. The system has been designed for the monitoring of large freeze dryers, but its characteristics make it useful in many other vacuum conditions. The system is capable of monitoring the temperature of hundreds of points with an uncertainty of the order of a degree and with a cost per point of a few euros
A Remotely Controlled Calibrator for Chemical Pollutant Measuring-Units
Full text linkThe increasing diffusion of pollutant measuring units, which are installed over wide areas, along with the short calibration interval of several sensors for pollutant quantities, requires new calibration infrastructures to be developed. This paper describes an attempt to develop an innovative calibration system which is based on traveling standards and which does not require units to be removed from the measuring site during the calibration process. The calibration system is based on a traveling standard, which is composed of one or more cylinders that contain gas mixtures, a cell with standard sensors, and a control unit with networking capabilities, which allows the traveling standard to be remotely exercised. A prototype of the proposed system is described and the preliminary results reporte
A Plug&Play Architecture for Low-Power Measurement Systems
No full textThis paper describes a measurement system architecture designed to be employed in the presence of hard power-supply constraints. The architecture is based on a system controller and on a set of measurement modules connected through a multi-drop bus. The power requirements are fulfilled by means of a power management strategy so that modules are powered sequentially. The modules are composed of a measuring device, either custom-made or commercial, and of a control interface specifically designed to implement hot-swap and plus&play features. In this way, modules can be added to the measurement system also during a measurement session. The paper also describes an example of temperature measurement system based on the proposed architectur
Wireless sensor network architecture for remote non-invasive museum monitoring
No full textThis paper describes a sensor network architecture developed for museum monitoring. The proposed solution is based on a distributed environment composed of small, nearly invisible measuring nodes that wireless connect to Arduino-based WiFi routers to reach a distributed cloud. Users can connect to the measuring system by using their smart-phones and can receive alerts and measurements in real-time. The entire architecture is based on the available μPanel environment and can be deployed and adapted to the actual conditions in a timely and easy manner. The application described in this paper makes reference to the museum environment, but can seamlessly adapted to several other situation
Arduino-based portable system for bioelectrical impedance measurement
No full textElectrochemical Impedance Spectroscopy (EIS) has been recently proposed as a simple non-invasive technique to monitor the amount of fat and liquids contained inside the human body. While the technique capabilities are still questioned, a simple and low cost device capable of performing this kind of measurements would help testing it on many patients with minimal effort. This paper describes an extremely low cost implementation of an EIS system suitable for medical applications that is based on a simple commercial Arduino Board whose cost is below 50$. The circuit takes advantage of the ADC and DAC made available by the microcontroller of the Arduino boards and employs a logarithmic amplifier to extend the impedance measuring range to 6 decades without using complex programmable gain amplifiers. This way the device can use electrodes with sizes in the range of 1 cm2 to 40 cm2. The EIS can be measured in the frequency range of 1 Hz to 100 kHz and in the impedance range of 1 kΩ to 1 GΩ. The instrument automatically compensates the DC voltage due to the skin/electrode contact and runs on batteries. The EIS traces can be stored inside the device and transferred to the PC with a wireless link avoiding safety issue
Low-Cost Laser-Based Localization System for Agricultural Machines
Full text linkThis paper describes the design and test of a low-cost localization system for agricultural applications, which determines a tractor position in fields up to 0.5 km with an uncertainty of about 1 m. The proposed system employs a standard unmodified laser head, which is commonly used for field leveling, plus a reference ground-fixed laser receiver and requires neither laser modulation nor expensive time-of-flight measurements of light beam
Noninvasive Solution for Electrochemical Impedance Spectroscopy on Metallic Works of Art
Full text linkMetallic works of art of cultural relevance are continuously subjected to corrosion as the environment becomes increasingly polluted. A fast and simple method to in situ assess the conservation conditions is therefore required. This paper describes the development and performance of dry and gel-based electrodes which can be used to assess the surface conservation state without the need to move the artifacts and which do not cause any damage to them. The electrodes can be used with a portable electrochemical impedance spectroscopy system, without employing electrochemical cells. The proposed solution does not provide all the information that one can obtain using an electrochemical cell, but it can discriminate between protective coatings. It can be used to assess the protective capability of corrosion product layers and natural patinas, and it can therefore enable a noninvasive routine surface assessment to be conducted that could be extremely useful for people working in the field of conservation of cultural heritag
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