Geodynamic

Some surveyors claimed that problems were experienced when one collects GPS observations beneath high voltage power lines. They had reported quite large anomalies. Still others had reported no problems beneath high voltage power lines. Several tests were performed by RTK beneath or close to high voltage power lines , radar towers, generators and cell phone towers. A complete loss of ambiguities initialization was occurred. This is mainly due to wireless interruption, failed in transmitting the base data to the rover unit. To see the effect of the high voltage power medium on the pure GPS signal, we need to separate the interruption of the transmitting medium of base station data from the GPS signal. Thus, the current paper studies the effect of high voltage power lines (HVP) only on differential static GPS and post processing kinematic observations and the related results. The study is based upon investigating the effect of the HVP on GPS stations located directly beneath or close to the power lines with other stations more away from the HVP. The results show that the obtained coordinates are not affected in static mode while the epoch-wise coordinates are insignificantly affected by the HVP. , Radaranlagen, Stromgeneratoren und Mobilfunkmasten durchgeführt. Aufgrund von Unterbrechungen bei der Datenübertragung von der Referenzstation zum Rover konnten die Mehrdeutigkeiten oftmals nicht gelöst werden. Um den Einfluss von Hochspannungsleitungen auf das reine GPS-Signal zu untersuchen, muss dieser Effekt von den Störungen auf die Datenübertragung getrennt werden. Folglich wird im nachfolgenden Beitrag der Einfluss von Hochspannungsleitungen (im Folgenden HVP = high voltage powerlines) nur auf differenzielles statisches GPS und im Postprocessing prozessierte kinematische GPS-Beobachtungen untersucht. Die GPS-Punkte befinden sich hierbei direkt unter bzw. in der Nähe von HVP's aber auch weiter entfernt, um Referenzdaten für einen Vergleich zu erhalten. Die Untersuchungsergebnisse zeigen, dass die prozessierten Koordinaten im statischen Fall nicht durch die HVP beeinflusst werden, während die epochenweisen Lösungen einen schwachen Einfluss aufweisen.

The strategic importance of the area of Lake Nasser, where the High Dam exists, utilizes an accurate heights control for many aspects such as the determination of the lake level and the sedimentation rate at the bottom of the lake. GPS can be dedicating as a leveling control within this region only if the geoid undulations are accurately determined.

The advent of GPS Real-Time kinematic (RTK) in recent years has realized a significant advancement of GPS to provide three dimensional navigation at the centimeter level of accuracy. One of the fastest emerging trends in hydrographic surveying is the use of the vertical component of RTK GPS to determine real-time water level corrections. Accurate heave measurements are a critical component of the measurement of a hydrographic survey vessel's vertical motion. In the current research we submitted a new algorithm for computing the heave component in real time based on utilizing the ellipsoidal height produced by used single frequency GPS receiver positioning system in the bathymetry process. An evaluation process of the Heave-GPS based on a comparative study with the classical TSS-DMS05 heave compensator is discussed.

Terrestrial laser scanning has become one of the standard technologies for object acquisition
in surveying engineering. The high spatial resolution of imaging and the excellent capability
of measuring the 3D space by laser scanning bear a great potential if combined for both data acquisition
and data compilation. Automatic crack detection from concrete surface images is very effective
for nondestructive testing. The crack information can be used to decide the appropriate
rehabilitation method to fix the cracked structures and prevent any catastrophic failure. In practice,
cracks on concrete surfaces are traced manually for diagnosis. On the other hand, automatic crack
detection is highly desirable for efficient and objective crack assessment.
The current paper submits a method for automatic concrete cracks detection and mapping from
the data that was obtained during laser scanning survey. The method of cracks detection and mapping
is achieved by three steps, namely the step of shading correction in the original image, step of
crack detection and finally step of crack mapping and processing steps. The detected crack is
defined in a pixel coordinate system. To remap the crack into the referred coordinate system, a
reverse engineering is used. This is achieved by a hybrid concept of terrestrial laser-scanner point
clouds and the corresponding camera image, i.e. a conversion from the pixel coordinate system
to the terrestrial laser-scanner or global coordinate system. The results of the experiment show that
the mean differences between terrestrial laser scan and the total station are about 30.5, 16.4 and 14.3
mms in x, y and z direction, respectively.

Some surveyors claimed that problems were experienced
when one collects GPS observations beneath high voltage
power lines. They had reported quite large anomalies. Still
others had reported no problems beneath high voltage power
lines. Several tests were performed by RTK beneath or close to
high voltage power lines (Gibing et. al., 2001), radar towers,
generators and cell phone towers. A complete loss of ambiguities
initialization was occurred. This is mainly due to wireless
interruption, failed in transmitting the base data to the
rover unit.
To see the effect of the high voltage power medium on the
pure GPS signal, we need to separate the interruption of the
transmitting medium of base station data from the GPS signal.
Thus, the current paper studies the effect of high voltage
power lines (HVP) only on differential static GPS and post
processing kinematic observations and the related results. The
study is based upon investigating the effect of the HVP on
GPS stations located directly beneath or close to the power
lines with other stations more away from the HVP. The results
show that the obtained coordinates are not affected in static
mode while the epoch-wise coordinates are insignificantly
affected by the HVP.

The present work focuses on the evaluation of the new Earth Gravitational Model (EGM2008) that
was recently released by the NGA (National Geospatial-Intelligence Agency, U.S)/EGM-development
team. The Earth Gravitational Model (EGM2008) is the highest resolution model up to degree 2160 which
has been developed and published. EGM2008 incorporates improved 5x5 minutes gravity anomalies and
has benefited from the latest GRACE based satellite solutions.
This paper presents an overview of the evaluation results for the new Earth Gravitational Model
EGM2008 by using GPS and leveled elevations, orthometric heights, over four test areas in Kuwait. The
main goal of this research is to find answers to the following question: is EGM2008 the best available
Geoidal Model for Kuwait? The results of EGM08 application over the three tested areas confirmed that
EGM08, without any doubt, makes good contribution to the geodetic vertical control.

Dredge quantity estimation is a critical issue in dredging projects as it has direct impact on the project process and cost. Hydrographic survey is the main tool for measuring the horizontal coordinates and vertical levels of the sea bed and subsequently quantity estimation. Heave is one of the factors that did not mentioned by " IHO Standards for Hydrographic Survey, (2008) " to be measured in its specifications. They only mentioned that for Sweep Systems (multi-transducers arrays): " Once the heave on the transducers exceeds the maximum allowable value in the uncertainty budget, sounding operations should be discontinued until sea conditions improve ". In dredging works, some consultants insisted to use at least heave motion sensor in doing the bathymetric survey works especially for harbors dredging works in spite of the survey works will cover all aspects of IHO special order and/or order " A " classes. No previous study was done to see how the effe...

DESCRIPTION To evaluate the HARN & NACN, a co-joint team from NRIAG and Mansura University observed the available HARN & NACN stations in the Nile Delta. The Processing of the tested part was done by CSRS-PPP Service based on utilizing Precise Point Positioning “PPP” and Trimble Business Center “TBC”. The study shows the feasibility of Precise Point Positioning in updating the absolute positioning of the HARN network and its role in updating the reference frame (ITRF). The study also confirmed the necessity of the absent role of datum maintenance of Egypt networks.

Ionospheric delay, can be derived from dual frequency Global Navigation Satellite Systems (GNSS) signals, and then converted into the Vertical Total Electron Contents (VTEC) along the signal path. Various models were devised to calculate VTEC, such as spherical harmonics model and Taylor Series Expansion model. According to density of electron ionosphere can be divided into several layers where electrons reaches peak value at altitude of 350 km. for two-dimension ionosphere modeling, the ionosphere is assumed to be concentrated on a spherical shell of a thin layer located at the altitude of about 350 km above Earth. The primary goal of the current research to develop an algorithm capable of producing VTEC maps on an hourly basis, using carrier phase observations from dual frequency GPS receiver. The developed algorithm uses a single GPS station (Zero-difference) to map VTEC over a regional area. The carrier phase measurements are much more precise than the code pseudorange measurements, but they contain an ambiguous term. If such ambiguities are fixed, thence the carrier phase measurements become as unambiguous pseudoranges, but accurate at the level of few millimeters. In current research Sequential Least Square Adjustment (SLSA) was considered to fix ambiguity term in carrier phase observations. The proposed algorithm was written using MATLAB and Called (ZDPID). Two GPS stations (ANKR and BSHM) were used from IGS network to evaluate the developed code, VTEC values were estimated over these two stations. Results of the proposed algorithm were compared with the Global Ionosphere Maps (GIMs), which is generally used as a reference. The results show that the mean difference between VTEC from GIM and estimated VTEC at ANKR station is ranging from-2.1 to 3.67 TECU and its RMS is 0.44. The mean difference between VTEC from GIM and estimated VTEC at BSHM station is ranging from-0.29 to 3.65 TECU and its RMS is 0.38. Another three GPS stations in Egypt were used to generate regional ionosphere maps over Nile Delta, Egypt. The mean differences between VTEC from GIM and estimated VTEC at SAID station is ranging from-1.1 to 3.69 TECU and its RMS is 0.37, from-1.29 to 3.27 TECU for HELW station with RMS equal 0.39, and from 0.2 to 4.2 TECU for BORG station with RMS equal 0.46. Therefore, the proposed algorithm can be used to estimate VTEC efficiently.

The first main motivation of this thesis is using the GPS data to compute the orthometric height by simple polynomial techniques and filter the data by least square method using Matlab program. Control vertical networks consisting of ellipsoidal, orthometric and geoid height data are investigated. Although the theoretical relationship between these height types is simple in nature discrepancies among the combined height data, its practical implementation has proven to be quite challenging due to numerous factors that cause, with particular emphasis on (i) modeling a technique to compute the geoid undulation from GPS and precise leveling, (ii) correcting the observed geoid undulation by least square method. To address these challenges, a general procedure involving empirical and statistical tests for assessing the performance of selected parametric models is developed. Additional numerical studies include the obtained of geoid models (local geoid), scaling the GPS-derived ellipsoidal...