Positioning Evaluation of Single and Dual-Frequency Low-Cost GNSS Receivers Signals Using PPP and Static Relative Methods in Urban Areas

A positional accuracy obtained by the Precise Point Positioning and static relative methods was compared and analyzed. Test data was collected using low-cost GNSS receivers of single- and dual-frequency in urban areas. The data was analyzed for quality using the TEQC program to determine the degree of affectation of the signal in the urban area. Low-cost GNSS receivers were found to be sensitive to the multipath effect, which impacts positioning. The horizontal and vertical accuracy was evaluated with respect to Mexican regulations for the GNSS establishment criteria. Probable Error Circle (CEP) and Vertical Positioning Accuracy (EPV) were performed on low cost GNSS receiver observation data. The results show that low-cost dual-frequency GNSS receivers can be used in urban areas. The precision was obtained in the order of 0.013 m in the static relative method. The results obtained are comparable to a geodetic receiver in a geodetic baseline of <20 km. The study does not recommend using single and dual frequencies low cost GNSS receivers based on results obtained by the Precise Point Positioning (PPP) method in urban areas. The inclusion of the GGM10 model reduces the vertical precision obtained by using low cost GNSS receivers in both methods, conforming to the regulations only in the horizontal component.

Optimization of the drive mechanism with lead screw using Isight software

The ball screws are characterized with better positioning accuracy and higher efficiency and load ratings than the same size lead screw, but still cannot fully replace their functionality mostly due to the self-locking. Leads screws are recommended especially for such applications as grippers, lifters, presses and vertical positioning drives. By proper selection of the lead screw geometrical features and application of the modern materials, it is possible to obtain much more advantageous parameters of the drive system. In this paper, the methodology of optimization of the drive mechanism with lead screw using Isight software is presented. The performed sensitivity analysis allowed not only to find the influence of various constructional features such as: size of the thread, length of the screw and material properties, on the maximum load capacity of the drive mechanism and its inertia, but also determine its scale impact. The obtained results can improve the design process of lead screw mechanism.

Analysis of serve and serve return on different surfaces in elite tennis players

The aim of the current study was to analyze players’ interactions in serve and serve return situations and examine the way points were decided due to players’ positions and surfaces. Fourteen ATP 1000 tournament matches were analyzed (7 on hard surface; 7 on clay surface). The type of surface did not affect the way points ended (χ²=9.26; p > 0.05) but did influence serve return vertical positioning (χ²=270.86; p < 0.001). The return positioning, both lateral (χ²=92.68; p < 0.001 on deuce side - χ² = 78.98; p < 0.001 on advantage side) and vertical (χ²=33.59; p < 0.001), and the type of serve (χ²=45.13; p < 0.001) affected the way points were decided. The results from the present study suggest that tennis players should use, or at least seek, strategies based on aggressiveness and consistency of the 1st serve and also indicate that in the 2nd serve return, players are more offensive, and that on hard surfaces, players stand a few steps inside the court to return the serve, differently from clay surfaces. It recommended that serve returns should combine aggression, by inside the court positioning, and accuracy.

Perspectives on Larval Behaviour in Biophysical Modelling of Larval Dispersal in Marine, Demersal Fishes

Biophysical dispersal models for marine fish larvae are widely used by marine ecologists and managers of fisheries and marine protected areas to predict movement of larval fishes during their pelagic larval duration (PLD). Over the past 25 years, it has become obvious that behaviour—primarily vertical positioning, horizontal swimming and orientation—of larvae during their PLD can strongly influence dispersal outcomes. Yet, most published models do not include even one of these behaviours, and only a tiny fraction include all three. Furthermore, there is no clarity on how behaviours should be incorporated into models, nor on how to obtain the quantitative, empirical data needed to parameterize models. The PLD is a period of morphological, physiological and behavioural change, which presents challenges for modelling. The present paper aims to encourage the inclusion of larval behaviour in biophysical dispersal models for larvae of marine demersal fishes by providing practical suggestions, advice and insights about obtaining and incorporating behaviour of larval fishes into such models based on experience. Key issues are features of different behavioural metrics, incorporation of ontogenetic, temporal, spatial and among-individual variation, and model validation. Research on behaviour of larvae of study species should be part of any modelling effort.

Horizontal and vertical labour market movements in Austria: Do occupational transitions take women across gendered lines?

The gendered division of occupations is a persistent characteristic of the Austrian labour market. Furthermore, we can observe more flexible employment biographies, where sequential employment episodes and occupational transitions become an important part. On this account, the article argues that both gender inequalities and labour market movements need to be examined simultaneously. The authors therefore analyse gender-(un)typed horizontal occupational transitions and their influence on the vertical positioning, based on the Austrian Micro Census (2008–2018). The results reveal that gender-typed occupational transitions are regaining relevance and that the gender effect is reversing in that women increasingly leave gender-untyped occupations. The findings also demonstrate that this gender-typed horizontal movement yields a significant decline in occupational status for women, which even increases when women become mothers. Based on their models the authors find no negative effects for fathers.