Split Distributed Computing in Wireless Sensor Networks

We designed a novel method intended to improve the performance of distributed computing in wireless sensor networks. Our proposed method is designed to rapidly increase the speed of distributed computing and decrease the number of the messages required for a network to achieve the desired result. In our analysis, we chose Average consensus algorithm. In this case, the desired result is that every node achieves the average value calculated from all the initial values in the reduced number of iterations. Our method is based on the idea that a fragmentation of a network into small geographical structures which execute distributed calculations in parallel significantly affects the performance

Connectivity-Based Self-Localization in WSNs

Efficient localization methods are among the major challenges in wireless sensor networks today. In this paper, we present our so-called connectivity based approach i.e, based on local connectivity information, to tackle this problem. At first the method fragments the network into larger groups labeled as packs. Based on the mutual connectivity relations with their surrounding packs, we identify border nodes as well as the central node. As this first approach requires some a-priori knowledge on the network topology, we also present a novel segment-based fragmentation method to estimate the central pack of the network as well as detecting so-called corner packs without any a-priori knowledge. Based on these detected points, the network is fragmented into a set of even larger elements, so-called segments built on top of the packs, supporting even more localization information as they all reach the central node

The Distributed Convergence Classifier Using the Finite Difference

The paper presents a novel distributed classifier of the convergence, which allows to detect the convergence/the divergence of a distributed converging algorithm. Since this classifier is supposed to be primarily applied in wireless sensor networks, its proposal makes provision for the character of these networks. The classifier is based on the mechanism of comparison of the forward finite differences from two consequent iterations. The convergence/the divergence is classifiable only in terms of the changes of the inner states of a particular node and therefore, no message redundancy is required for its proper functionality

A New Combined European Permanent Network Station Coordinates Solution

The EUREF (International Association of Geodesy (IAG) Reference Frame Sub-Commission for Europe) network of continuously operating GPS stations (EPN) was primarily established for reference frame maintenance, and also plays an important role for geodynamical research in Europe. The main goal of this paper is to obtain an independent homogeneous time-series of the EPN station coordinates, which is also available in SINEX format. A new combined solution of the EPN station coordinates was computed. The combination was performed independently for every week, in three steps: 1. the stated constraints on the coordinates were removed from the individual solutions of the Analysis Centers; 2. the de-constrained solutions were aligned to ITRF2000; 3. the resulting solutions were combined using the Helmert block-ing technique. All the data from GPS week 900 to week 1302 (April 1997 - December 2004) were used. We investigated in detail the behavior of the transformation parameters aligning the new combined solution to ITRF2000. In general, the time-series of the transformation parameters show a good stability in time although small systematic effects can be seen, most likely caused by station instabilities. A comparison of the new combined solution to the official EUREF weekly combined solution is also presented

Expression of invasion-related extracellular matrix molecules in human glioblastoma versus intracerebral lung adenocarcinoma metastasis

Tumor cell invasion into the surrounding brain tissue is mainly responsible for the failure of radical surgical resection, with tumor recurrence in the form of microdisseminated disease. Extracellular matrix (ECM)-related molecules and their receptors predominantly participate in the invasion process, including cell adhesion to the surrounding microenvironment and cell migration. The extent of infiltration of the healthy brain by malignant tumors strongly depends on the tumor cell type. Malignant gliomas show much more intensive peritumoral invasion than do metastatic tumors. In this study, the mRNA expression of 30 invasion-related molecules (twenty-one ECM components, two related receptors, and seven ECM-related enzymes) was investigated by quantitative reverse transcriptase-polymerase chain reaction. Fresh frozen human tissue samples from glioblastoma (GBM), intracerebral lung adenocarcinoma metastasis, and normal brain were evaluated. Significant differences were established for 24 of the 30 molecules. To confirm our results at the protein level, immunohistochemical analysis of seven molecules was performed (agrin, neurocan, syndecan, versican, matrix metalloproteinase 2 [MMP-2], MMP-9, and hyaluronan). Determining the differences in the levels of invasion-related molecules for tumors of different origins can help to identify the exact molecular mechanisms that facilitate peritumoral infiltration by glioblastoma cells. These results should allow the selection of target molecules for potential chemotherapeutic agents directed against highly invasive malignant gliomas

On Standard Reductions to Relative Gravity Measurements. A Case Study Through the Establishment of the New Local Gravity Net in the Province of Valencia (Spain)

This is an author's accepted manuscript of an article published in: “Survey Review"; Volume 43, Issue 319, 2011; copyright Taylor & Francis; available online at: http://dx.doi.org/10.1179/003962610X12747001420825Standard reductions to gravity readings due to Earth tides, ocean loading and attraction, polar motion, instrumental height and air pressure variations and loading of atmospheric masses are studied in this paper from a practical point of view, that is, taking into account their numerical values and their influence on gravimetric readings and relative gravimetric observations. The study was carried out using the observations and definition of a new local gravimetric net. This new local gravimetric net has been established in the province of Valencia (Eastern Spain) to meet the increasing requirements of geophysics, geology, geodesy and geodynamics. The net comprises 21 sites, which are an average of 45 km apart and was measured using Lacoste & Romberg D203 and G301 gravimeters. Gravity values were determined using one fixed station in relation to an absolute one and 202 relative gravimetric observables. Reductions are applied for Earth tides (with real accurate amplitude and phase-difference for the principal tidal waves analysed from 301 digitally recorded days of gravity readings) where oceanic attraction and loading has been considered. In addition, reductions for polar motion, vertical gradient to instrument height and air pressure and loading of atmospheric masses have been applied. The net was established using least square adjustment where the weights of each relative gravimetric observable were determined by iterative estimation in accordance with the Huber robust estimation procedure. Obtained standard deviations of the final gravity values have an average value of 18x10-8 ms-2 (18 µGal), minimum value of 10x10-8 ms-2 and maximum value of 26x10-8 ms-2 . The statistical analysis of the results concludes with a precision and reliability determination. Discussion of the numerical values obtained in the standard gravimetric reductions shows the importance of each one in the final solution, bearing in mind that the relative gravimetric observables have been obtained using Lacoste & Romberg instruments and the geographical location of the net. The main conclusion is that only Earth tides reduction (with approximate amplitude and phase-difference numbers for the principal tidal waves) have to be taken into accountMartín Furones, ÁE.; Anquela Julián, AB.; Padin Devesa, J.; Berné Valero, JL. (2011). On Standard Reductions to Relative Gravity Measurements. A Case Study Through the Establishment of the New Local Gravity Net in the Province of Valencia (Spain). Survey Review. 43(319):16-29. doi:10.1179/003962610X12747001420825S162943319Boedecker, G., & Richter, B. (1981). The new gravity base net 1976 of the Federal Republic of Germany (DSGN 76). Bulletin Géodésique, 55(3), 250-266. doi:10.1007/bf02530865Cartwright, D. E., & Tayler, R. J. (2007). New Computations of the Tide-generating Potential. Geophysical Journal of the Royal Astronomical Society, 23(1), 45-73. doi:10.1111/j.1365-246x.1971.tb01803.xCharles, K. and Hipkin, R.G. 1994. British precise gravity net 1993. Joint symposium of the International Gravity Comission and the International Geoid Comission, Symposium 113: 39–45, Graz, Austria. Ed. Springer-Verlag.Farrell, W. E. (1972). Deformation of the Earth by surface loads. Reviews of Geophysics, 10(3), 761. doi:10.1029/rg010i003p00761Jentzsch, G. (s. f.). Earth tides and ocean tidal loading. Lecture Notes in Earth Sciences, 145-171. doi:10.1007/bfb0011461Torge, W. 1989. Gravimetry. Ed. Walter de Gruyter, Berlin-New York. 465 pages.Wahr, J. M. (1985). Deformation induced by polar motion. Journal of Geophysical Research, 90(B11), 9363. doi:10.1029/jb090ib11p09363Wenzel, G. 1998. Format and structure for the exchange of high precision tidal data, http://www.ife.uni-hannover.de/∼Wenzel/format/format.html, acceded on February 1999

Regional integration of long-term national dense GNSS network solutions

The EUREF Permanent Network Densification is a collaborative effort of 26 European GNSS analysis centers providing series of daily or weekly station position estimates of dense national and regional GNSS networks, in order to combine them into one homogenized set of station positions and velocities. During the combination, the station meta-data, including station names, DOMES numbers, and position offset definitions were carefully homogenized, position outliers were efficiently eliminated, and the results were cross-checked for any remaining inconsistencies. The results cover the period from March 1999 to January 2017 (GPS week 1000-1933) and include 31 networks with positions and velocities for 3192 stations, well covering Europe. The positions and velocities are expressed in ITRF2014 and ETRF2014 reference frames based on the Minimum Constraint approach using a selected set of ITRF2014 reference stations. The position alignment with the ITRF2014 is at the level of 1.5, 1.2, and 3.2\ua0mm RMS for the East, North, Up components, respectively, while the velocity RMS values are 0.17, 0.14, and 0.38\ua0mm/year for the East, North, and Up components, respectively. The high quality of the combined solution is also reflected by the 1.1, 1.1, and 3.5\ua0mm weighted RMS values for the East, North, and Up components, respectively

Regional integration of long-term national dense GNSS network solutions

The EUREF Permanent Network Densification is a collaborative effort of 26 European GNSS analysis centers providing series of daily or weekly station position estimates of dense national and regional GNSS networks, in order to combine them into one homogenized set of station positions and velocities. During the combination, the station meta-data, including station names, DOMES numbers, and position offset definitions were carefully homogenized, position outliers were efficiently eliminated, and the results were cross-checked for any remaining inconsistencies. The results cover the period from March 1999 to January 2017 (GPS week 1000-1933) and include 31 networks with positions and velocities for 3192 stations, well covering Europe. The positions and velocities are expressed in ITRF2014 and ETRF2014 reference frames based on the Minimum Constraint approach using a selected set of ITRF2014 reference stations. The position alignment with the ITRF2014 is at the level of 1.5, 1.2, and 3.2 mm RMS for the East, North, Up components, respectively, while the velocity RMS values are 0.17, 0.14, and 0.38 mm/year for the East, North, and Up components, respectively. The high quality of the combined solution is also reflected by the 1.1, 1.1, and 3.5 mm weighted RMS values for the East, North, and Up components, respectively

The apparent British sea slope is caused by systematic errors in the levelling-based vertical datum

The spirit-levelling–based British vertical datum (Ordnance Datum Newlyn) implies a south–north apparent slope in mean sea level of up to 53 mm deg–1 latitude, due to the datum falling on heading northwards. Although this apparent slope has been investigated since the 1960s, explanations of its origin have remained inconclusive. It has also been suggested that, rather than a slope, the British vertical datum includes a step of about 240 mm affecting all sites north of about 53°N. In either case, the British vertical datum may be of limited use for any study requiring accurate heights or changes in heights, such as testing geoid models, groundwater and hydrocarbon extraction, the calibration and validation of satellite-based digital terrain models, and the unification of vertical datums internationally. Within the last decade, however, based on an apparent reduction in the slope to only −12 mm deg–1 latitude with respect to recent geoid models, it has been claimed that the British vertical datum does provide a physically meaningful surface for use in scientific applications.In this paper, we reinvestigate the presence of apparent south–north sea slopes around Britain and reported slopes in the vertical datum, using the EGM2008 global gravitational model, together with mean sea level and GPS data from British tide gauges, GPS ellipsoidal heights of 178 fundamental benchmarks across mainland Britain, and vertical deflection observations at 192 stations. We demonstrate a south–north slope in the British vertical datum of −(20–25) mm deg–1 latitude with respect to both mean sea level (corrected for the ocean's mean dynamic topography and the inverse barometer response to atmospheric pressure loading) and the EGM2008 quasigeoid model, while EGM2008 is shown to exhibit a negligible slope of (2 ± 4) mm deg–1 with respect to mean sea level. It is clear, therefore, that the slope can only arise from systematic errors in the levelling, although we are unable to isolate their exact origin. Using an offset detection method based on a penalized likelihood maximization using the Schwarz Information Criterion, we do not detect a step in the vertical datum affecting all sites north of 53°N, but do identify regional distortions that we attribute to the inhomogeneity in both the levelling data used and the least squares adjustment procedures used to realize the datum. We conclude that the British vertical datum remains unsuitable for scientific purposes