Long term time stability of conventional GPS receivers

Author(s):  
K. Kalliomaki ◽  
T. Mansten ◽  
H. Koivula ◽  
J. Mannermaa
Keyword(s):  
Author(s):  
Santiago García

With the rapid development of smart phones, tablets and their operative systems, many positioning enabled sensors have been built into these devices. Users can now accurately fix their location according to the function of GPS receivers. For indoor environments, as in the case we are studying, WiFi based positioning is preferred to GPS due to the attenuation or obstruction of signals. This paper deals with the automatic classification of customers in a Sports Shop Center on the basis of their movements around the shop's premises. To achieve this goal, we start by collecting (x,y) coordinates from customers while they visit the store. Consequently, any costumer's path through the shop is formed by a list of coordinates, obtained with a frequency of one measurement per minute. Then, a guess about the full trajectory is constructed and a number of parameters about these trajectories is calculated before performing an Unsupervised Learning Clustering Process. As a result, we can identify several types of customers, and the dynamics of their behavior inside the shop. This information is of great value to the company, to be used both in the long term and also in short periods of time, monitoring the current state of the shop at any moment, identifying different types of situation appearing during restricted periods, or predicting customer flow conditions


Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2592 ◽  
Author(s):  
Marek Przyborski ◽  
Jerzy Pyrchla ◽  
Krzysztof Pyrchla ◽  
Jakub Szulwic

The article discusses the registration of micro-gravity changes with the MGS-6 Micro-g LaCoste gravity sensor during static measurements. An experiment was carried out to determine how small changes in gravity can be registered using the MGS-6 system sensor. The tides of the Earth’s crust were chosen as the source of disturbance of the field with small amplitude and long-term changes. The tested sensor was placed in a geophysical observatory on a specially designed tripod. Simultaneously on the nearby concrete pillar, the registration of changes in gravity was carried out using the superconducting iGrav gravimeter. The high temporal stability of the superconducting gravimeters and the low noise combined with leading sensitivity of its reading allow it to be considered as a reliable reference source for MGS-6. The article discusses the impact of non-leveling changes of the MGS-6 gravimetry on the reading and determines the size of its non-linear drift. The obtained differences in indications between devices did not exceed 50 μ Gal for 68% of data. The measurements also showed excellent time stability of the MGS-6 measurement system. The data collected during the experiment allowed determining the level of accuracy that can be sought during real measurements using the MGS-6 system on research vessels. They also give an overview of the dynamics of the drift phenomenon of the analyzed research system.


2011 ◽  
Vol 26 (4) ◽  
pp. 231-243 ◽  
Author(s):  
H.J. Möller ◽  
M. Jäger ◽  
M. Riedel ◽  
M. Obermeier ◽  
A. Strauss ◽  
...  

AbstractObjectiveIn the context of the development of DSM-V and ICD-11 it appears to be useful to get further data on the validity of the diagnostic differentiation between schizophrenic and affective disorders. This study investigated the relevance of the main diagnostic groups schizophrenia, schizoaffective psychosis and affective disorder in the context of different diagnostic systems (ICD-9, ICD-10, DSM –IV), assessing their time stability, long-term courses, types and functional outcome.MethodsA total of 323 first hospitalized inpatients of the Psychiatric Department of the University Munich were recruited at index time. The full follow-up evaluation including standardized assessment procedures could be performed in 197 patients.ResultsThe re-diagnosis of the patients’ disorders shows that with the transition from ICD-9 to ICD-10 or DSM-IV, the group of affective disorders increased numerically while the diagnostic groups of schizophrenia and schizoaffective disorders decreased in size. The structured clinical interview for DSM-IV (SCID) analysis showed that altogether ICD-10 and DSM-IV had a relatively high diagnostic stability. Of the patients with an ICD-10 diagnosis of schizophrenia, 57% had a chronic course; 61% of the patients with a DSM-IV diagnosis of schizophrenia. Patients with affective disorders, according either to ICD-10 or DSM-IV, had in more than 90% of the cases an episodic-remitting course. In terms of prediction of long-term outcome regarding the differentiation between chronic and non-chronic course, the ICD-10 diagnoses did give a slightly better predictive result than a dimensional approach based on the key psychopathological syndrome scores.ConclusionsThe differentiation between schizophrenic and affective disorders seems meaningful especially under predictive aspects. A dimensional syndromatological description does not exceed the predictive power of the investigated main diagnostic categories, but might increase the clinically relevant information.


Author(s):  
B. V. Farmakovsky

The results of investigations of temperature and time stability of cast microwires in glass insulation from resistive alloys of nickel–chrome, cobalt–chromium and copper–nickel systems are presented. It is established that microwires from the investigated alloys retain their temperature stability at temperatures not lower than 350°C. An investigation of the time stability showed that changes in the electrical resistance during long-term storage of microwires (up to 1 year) do not occur in warehouse conditions, and despite the high degree of nonequilibrium of alloys during high-temperature hardening of the melt, relaxation phenomena are not observed. Consequently, the investigated microwires from alloys based on nickel, cobalt and copper are a very promising material for manufacturing thermostable resistive elements for precision instrumentation.


Sign in / Sign up

Export Citation Format

Share Document