Ionospheric scintillation causes rapid fluctuations of measurements from Global Navigation Satellite Systems (GNSSs), thus threatening space-based communication and geolocation services. The phenomenon is most intense in equatorial regions, around the equinoxes and in maximum solar cycle conditions. Currently, ionospheric scintillation monitoring receivers (ISMRs) measure scintillation with high-pass filter algorithms involving high sampling rates, e.g. 50 Hz, and highly stable clocks, e.g. an ultra-low-noise Oven-Controlled Crystal Oscillator. The present paper evolves phase scintillation indices implemented in conventional geodetic receivers with sampling rates of 1 Hz and rapidly fluctuating clocks. The method is capable to mitigate ISMR artefacts that contaminate the readings of the state-of-the-art phase scintillation index. Our results agree in more than 99.9% within ± 0.05 rad (2 mm) of the ISMRs, with a data set of 8 days which include periods of moderate and strong scintillation. The discrepancies are clearly identified, being associated with data gaps and to cycle-slips in the carrier-phase tracking of ISMR that occur simultaneously with ionospheric scintillation. The technique opens the door to use huge databases available from the International GNSS Service and other centres for scintillation studies. This involves GNSS measurements from hundreds of worldwide-distributed geodetic receivers over more than one Solar Cycle. This overcomes the current limitations of scintillation studies using ISMRs, as only a few tens of ISMRs are available and their data are provided just for short periods of time.

No abstract

Purpose The purpose of this paper is to find out the distribution of benefits, costs, and value added among the actors and problems in the practical management in dairy milk value chain, especially in one of the most important dairy areas in Vietnam to see how they upgrade in the value chain. Design/methodology/approach A survey was carried out in Bavi, Hanoi where a large amount of fresh milk is produced annually. The content of the survey was built before conducting in Bavi with 160 questionnaires. The questionnaires were based on the criteria which reflect the main objectives of the paper such as the actor’s profits and costs, the relationship among these actors, and the advantages and disadvantages in the dairy milk’s value chain. Some part of results of the paper was evaluated by conducting interviews with the relevant target groups in the value chain of dairy milk. Data collected were aggregated and analyzed by SPSS20, Excel. The calculation of cost and profit margin of each actor in the chain was also be presented by a quantitative tool for value chain analysis. Findings This study pointed out the systemized problems in the value chain of one of the biggest dairy companies in Vietnam. This study revealed some wicked problems in the value chains of Vietnam under globalization. Research limitations/implications This study could not cover all of the detailed actors in the dairy value chain. Originality/value The value of income in the chain is distributed unequally. The benefits that farmers receive are inadequate with the costs they have to pay. This is a particular chain, in which the main factors boosting the chain are factories, and an increase in revenue also reflects the benefits of them. The result is that the value added in the chain is also biased toward the dairy plant. The paper also pointed out the shortcomings in the cost calculation of farmers. All the expenses, such as wages and the opportunity cost, are calculated in the total cost of the dairy plant, whereas dairy farmers do not mention these costs. Thus, in terms of benefits, farmers suffer more disadvantages, thus they should be received more value. In terms of management, Bavi’s authorities could not manage the output of milk in the perfect way. The lax management has led to a series of counterfeit goods that appear on the market today. These low-quality products are sold right on the highway and the Bavi’s tourist destination.

No abstract