1,721,071 research outputs found
Evoluzione delle tecniche del rilevamento in ambito interdisciplinare dalla topografia alla geomatica
No full textDistribution of some statistics in presence of blunders in geodetic observations
No full textIn presence of gross errors (blunders) in the observations, we derive the distributions of some statistics defined after a least squares (LS) adjustment. Quadratic forms of the LS residuals and LS estimates of the blunders are considered along with some their combinations. We demonstrate, in two different ways, that the difference between the quadratic form of the LS residuals and the quadratic form of the LS estimates of the blunders has a central chi square distribution, while each of these two quadratic forms has a non central chi square distribution with the same non centrality parameter. Finally we prove the non central Fisher distribution of the ratio between the quadratic form of the LS estimates of the blunders and the difference of the above-mentioned quadratic forms
Caratteristiche biometriche ed analitiche dei frutti di 46 cultivar di albicocco vesuviane.
No full textCaratteristiche biometriche ed analitiche dei frutti di 46 cultivar di albicocco vesuviane.
No full textDistribution of some statistics in the presence of blunders in geodetic observations
No full textIn presence of gross errors (blunders) in the observations, we derive the distributions of some stati-stics defined after a least squares (LS) adjustment. Quadratic forms of the LS residuals and LS esti-mates of the blunders are considered along with some their combinations. We demonstrate, in two different ways, that the difference between the quadratic form of the LS residuals and the quadratic form of the LS estimates of the blunders has a central chi square distribution, while each of..
Caratteristiche biometriche ed analitiche dei frutti di 46 cultivar di albicocco vesuviane.
No full textCharacterization of dual frequency GNSS observations from Xiaomi Mi 8 smartphone in absence of duty cycle
No full textBeginning in May 2016 after Google announced that the GNSS raw measures (Global Navigation Satellite System) acquired by smartphones equipped with Android would be freely accessible, a real race began for scientists to achieve of centimeter accuracy using smartphone. A further acceleration took place in May 2018 with the appearance of the first dual-frequency GNSS chip-set the Broadcom BCM47755. The manufacturer Xiaomi marketed the first mobile phone equipped with this chip-set; for the first time smartphone users had access to raw double-frequency GNSS measurements from more than one satellite system. Unfortunately, the duty cycle technique, necessary to safeguard battery life, degraded the quality of the measurements acquired by the smartphone. The last milestone reached came with the release of the Android Pie operating system which makes it possible to switch off the duty cycle. Thus the use of high-precision techniques such as Real Time Kinematic (RTK) or Precise Point Positioning with the measurements acquired by the smartphone became possible. However, in order to use these techniques, it is necessary that the quality of the measurements is not too low. Therefore, it is very important to conduct an analysis to assess their quality. The results obtained show that the second frequency offers measurements that are much less sensitive to multipath, while the signal to noise ratio of the measurements is on average above 30 dB/Hz, guaranteeing a good quality. The results of the analysis conducted show that the quality of the measurements acquired by the smartphone has reached a quality sufficient to be able to use PPP or RTK techniques
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