Primary Realization of Inductance and Capacitance Scales With a Fully Digital Bridge

This article describes an automated electronic fully digital bridge for the comparison of four-terminal-pair (4TP) impedance standards in the audio frequency range. The bridge relative accuracy, which is on the order of 10-6, makes it suitable as a reference bridge for the realization of primary scales of inductance and capacitance in metrology institutes and calibration laboratories. The performances of this bridge were validated by comparing the results of the calibrations of inductance and capacitance standards with those obtained from an existing analog reference system based on the three-voltage method. The article also reports the results of this validation

A CIRCULAR LOOP TIME CONSTANT STANDARD

A time constant standard, developed for the phase angle measurement of precision current shunts is developed and described, and its time constant has been determined. Based on a single circular loop placed in an air thermostat, its construction is very simple and it gives accurate results in the frequency band of interest, e.g. for frequencies between 50 Hz and 100 kHz. The influence of the shielding is calculated using numerical Finite Element Analysis (FEA). The thermostatic stability is analyzed, and the time-constant of the thermostat is determined using temperature measurement and Butterworth filtering. The power coefficient of the standard is determined, and limits of errors are discussed

Applied Aspects of Modern Metrology

In the modern era of scientific and technological development, the role of measurements and metrology in scientific research is becoming more and more important due to the increase in the testing of various products. Moreover, requirements for the accuracy and reliability of measurement results are increasing significantly and their ranges are expanding. Improving measurement accuracy allows us to identify the shortcomings of certain technological processes and either eliminate them or reduce their influence. This leads to better-quality products and contributes to saving energy and other resources, as well as raw materials and materials. This book discusses relevant aspects of practical metrological activity to establish traceability of measurements while increasing their accuracy and reliability. It also presents procedures for the calibration and testing of measuring instruments

Aquaculture and rural livelihoods in the Bolivian Amazon - Systems of innovation and pro-poor technology development

This thesis is about pro-poor agricultural innovations and smallholder development in Amazonia. The focus is on aquaculture in the Bolivian Amazon, with particular reference to indigenous territories. An Innovation Systems framework is used to analyse aquaculture Research and Development at a national level and its relevance to small farmers. The analysis of poverty-focused technology development at the project and farm levels is aided by a Knowledge Engineering Approach for agricultural research management and Livelihoods perspectives. The data comes from interviews with fish farmers and other actors, on-farm and on-station research and livelihoods surveys. Indigenous-species aquaculture can help integrate conservation and development efforts in the region. Nevertheless, a weak innovation system, with limited participation of the public sector, and underdeveloped markets greatly limit poorer farmers’ access to aquaculture technologies. Furthermore, low-external-input systems often promoted as ‘pro-poor’ have limited growth potential whilst requiring considerable skills and labour, both of which tend to be in short supply in Amazonia. Development and poverty reduction objectives might be best met by supporting small and medium-scale commercial aquaculture in areas with access to input/output markets, developing institutional innovations in the provision of inputs and credit and building producer associations for bulk marketing. Given limited resources, priority should be given to reinforce existing innovation networks, largely within the private sector. Indigenous farmers with access to markets can also benefit from aquaculture with a commercial approach. There is considerable evidence of farmers in indigenous territories diversifying their production to include more market-oriented farming, as well as activities in the non-farm sector and wage labour. Here, interest in and access to aquaculture is influenced by location (access to markets and environmental settings), income portfolio and type of livelihoods diversification. The research has important implications for rural aquaculture development in the Bolivian Amazon and provides relevant data about livelihoods and change in indigenous communities and their implications for Conservation and Development Projects in Amazoni