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Monocular VO Scale Ambiguity Resolution Using an Ultra Low-Cost Spike Rangefinder

Positioning 2020年第4期11卷 45-60页

作者： ahmed el Amin ahmed el-rabbany Department of Civil Engineering Ryerson University Toronto Canada

Monocular visual odometry (VO) is the process of determining a user’s trajectory through a series of consecutive images taken by a single camera. A major problem that affects the accuracy of monocular visual odometry, however, is the scale ambiguity. This research proposes an innovative augmentation technique, which resolves the scale ambiguity problem of monocular visual odometry. The proposed technique augments the camera images with range measurements taken by an ultra-low-cost laser device known as the Spike. The size of the Spike laser rangefinder is small and can be mounted on a smartphone. Two datasets were collected along precisely surveyed tracks, both outdoor and indoor, to assess the effectiveness of the proposed technique. The coordinates of both tracks were determined using a total station to serve as a ground truth. In order to calibrate the smartphone’s camera, seven images of a checkerboard were taken from different positions and angles and then processed using a MATLAB-based camera calibration toolbox. Subsequently, the speeded-up robust features (SURF) method was used for image feature detection and matching. The random sample consensus (RANSAC) algorithm was then used to remove the outliers in the matched points between the sequential images. The relative orientation and translation between the frames were computed and then scaled using the spike measurements in order to obtain the scaled trajectory. Subsequently, the obtained scaled trajectory was used to construct the surrounding scene using the structure from motion (SfM) technique. Finally, both of the computed camera trajectory and the constructed scene were compared with ground truth. It is shown that the proposed technique allows for achieving centimeter-level accuracy in monocular VO scale recovery, which in turn leads to an enhanced mapping accuracy.

关键词： Spike Visual Odometry Monocular Scale

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Improved Between-Satellite Single-Difference Precise Point Positioning Model Using Triple GNSS Constellations: GPS, Galileo, and BeiDou

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Positioning 2016年第2期7卷 63-74页

作者： Akram Afifi ahmed el-rabbany Department of Civil Engineering Ryerson University Toronto Canada

This paper introduces a new dual-frequency precise point positioning (PPP) model, which combines the observations of three different GNSS constellations, namely GPS, Galileo, and BeiDou. Our model is based on between-satellite single-difference (BSSD) linear combination, which cancels out some receiver-related biases, including receiver clock error and non-zero initial phase bias of the receiver oscillator. The reference satellite can be selected from any satellite system GPS, Galileo, and BeiDou when forming BSSD linear combinations. Natural Resources Canada’s GPS Pace PPP software is modified to enable a combined GPS, Galileo, and BeiDou PPP solution and to handle the newly introduced biases. A total of four data sets at four IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the IGS-MGEX network are used to correct both of the GPS and Galileo measurements. It is shown that using the BSSD linear combinations improves the precision of the estimated parameters by about 25% compared with the GPS-only PPP solution. Additionally, the solution convergence time is reduced to 10 minutes for both BSSD scenarios, which represent about 50% improvement in comparison with the GPS-only PPP solution.

关键词： PPP BSSD GPS Galileo BeiDou

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Real-Time GPS/Galileo Precise Point Positioning Using NAVCAST Real-Time Corrections

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Positioning 2019年第3期10卷 35-49页

作者： Abdelsatar elmezayen ahmed el-rabbany Department of Civil Engineering Ryerson University Toronto Canada

Real-time precise point positioning (PPP) is possible through the use of real-time precise satellite orbit and clock corrections, which are available through a number of organizations including the International GNSS Service (IGS) real-time service (IGS-RTS). Unfortunately, IGS-RTS is only available for the GPS and GLONASS constellations. In 2018, a new real-time service, NAVCAST, which provides real-time precise orbit and clock corrections for the GPS and Galileo constellations, was launched. In this research, the potential performance of real-time PPP which makes use of NAVCAST real-time corrections is analyzed using various static and kinematic datasets. In the static dataset, 24 hours of observations from eight IGS stations in Canada over three different days were utilized. The static results show that the contribution of Galileo satellites can improve the positioning accuracy, with 30%, 34%, and 31% in east, north, and up directions compared to the GPS-only counterparts. In addition, centimeter-level positioning accuracy in the horizontal direction and decimeter-level positioning accuracy in the vertical direction can be achieved by adding Galileo observations. In the kinematic dataset, a real vehicular test was conducted in urban and suburban combined areas. The real-time kinematic GPS/Galileo PPP solutions demonstrate an improvement of about 53%, 45%, and 70% in east, north, and up directions compared to the GPS-only counterparts. It is shown that the real-time GPS/Galileo PPP can achieve a sub-decimeter horizontal positioning accuracy and about meter-level vertical positioning accuracy through the use of NAVCAST real-time corrections.

关键词： NAVCAST Static Kinematic GPS/Galileo PPP

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An Improved Model for Single-Frequency GPS/GALILEO Precise Point Positioning

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Positioning 2015年第2期6卷 7-21页

作者： Akram Afifi ahmed el-rabbany Department of Civil Engineering Ryerson University Toronto Canada

This paper introduces a new precise point positioning (PPP) model, which combines single-fre- quency GPS/Galileo observations in between-satellite single-difference (BSSD) mode. In the absence of multipath, all receiver-related errors and biases are cancelled out when forming BSSD for a specific constellation. This leaves the satellite originating errors and atmospheric delays un- modelled. Combining GPS and Galileo observables introduces additional biases that have to be modelled, including the GPS to Galileo time offset (GGTO) and the inter-system bias. This paper models all PPP errors rigorously to improve the single-frequency GPS/Galileo PPP solution. GPSPace PPP software of Natural Resources Canada (NRCan) is modified to enable a GPS/Galileo PPP solution and to handle the newly introduced biases. A total of 12 data sets representing the GPS/Galileo measurements of six IGS-MEGX stations are processed to verify the newly developed PPP model. Precise satellite orbit and clock corrections from IGS-MEGX networks are used for both GPS and Galileo measurements. It is shown that sub-decimeter level accuracy is possible with single-frequency GPS/Galileo PPP. In addition, the PPP solution convergence time is improved from approximately 100 minutes for the un-differenced single-frequency GPS/Galileo solution to approximately 65 minutes for the BSSD counterpart when a single reference satellite is used. Moreover, an improvement in the PPP solution convergence time of 35% and 15% is obtained when one and two reference satellites are used, respectively.

关键词： PPP GPS Galileo BSSD

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PPP Accuracy Enhancement Using GPS/GLONASS Observations in Kinematic Mode

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Positioning 2015年第1期6卷 1-6页

作者： Mahmoud Abd Rabbou ahmed el-rabbany Department of Civil Engineering Ryerson University Toronto Canada

Commonly, kinematic PPP techniques employ un-differenced ionosphere-free linear combination of GPS observations. This, however, may not provide continuous solution in urban areas as a result of limited satellite visibility. In this paper, the traditional un-differenced as well as between-satellite single-difference (BSSD) ionosphere-free linear combinations of GPS and GLONASS measurements are developed. Except GLONASS satellite clock products, the final precise GPS and GLONASS satellites clock and orbital products obtained from the multi-GNSS experiment (MGEX) are used. The effects of ocean loading, earth tide, carrier-phase windup, sagnac, relativity, and satellite and receiver antenna phase-center variations are rigorously modeled. Extended Kalman filter (EKF) is developed to process the combined GPS/GLONASS measurements. A comparison is made between three kinematic PPP solutions, namely standalone GPS, standalone GLONASS, and combined GPS/ GLONASS solutions. In general, the results indicate that the addition of GLONASS observations improves the kinematic positioning accuracy in comparison with the standalone GPS PPP positioning accuracy. In addition, BSSD solution is found to be superior to that of the traditional un-diffe- renced model.

关键词： GPS GLONASS PPP Kalman Filter (KF)

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Integration of Multi-Constellation GNSS Precise Point Positioning and MEMS-Based Inertial Systems Using Tightly Coupled Mechanization

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Positioning 2015年第4期6卷 81-95页

作者： Mahmoud Abd Rabbou ahmed el-rabbany Department of Civil Engineering Ryerson University Toronto Canada

We develop a new integrated navigation system, which integrates multi-constellations GNSS precise point positioning (PPP), including GPS, GLONASS and Galileo, with low-cost micro-electro-mechanical sensor (MEMS) inertial system, for precise positioning applications. To integrate GNSS and the MEMS-based inertial system, the process and measurement models are developed. Tightly coupled mechanism is adopted, which is carried out in the GNSS raw measurements domain. Both un-differenced and between-satellite single-difference (BSSD) ionosphere-free linear combinations of pseudorange and carrier phase GNSS measurements are processed. Rigorous models are employed to correct GNSS errors and biases. The GNSS inter-system biases are considered as additional unknowns in the integrated error state vector. The developed stochastic model for inertial sensors errors and biases are defined based on first order Gaussian Markov process. Extended Kalman filter is developed to integrate GNSS and inertial measurements and estimate inertial measurements biases and errors. Two field experiments are executed, which represent different real-world scenarios in land-based navigation. The data are processed by using our developed Ryerson PPP GNSS/MEMS software. The results indicate that the proposed integrated system achieves decimeter to centimeter level positioning accuracy when the measurement updates from GNSS are available. During complete GNSS outages the developed integrated system continues to achieve decimeter level accuracy for up to 30 seconds while it achieves meter-level accuracy when a 60-second outage is introduced.

关键词： GNSS GPS Galileo GLONASS MEMS PPP Tightly Coupled

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Mafic and felsic magmatism in the Wadi Kalalat area, South Eastern Desert, Egypt: mineralogy, geochemistry and geodynamic evolution during the Neoproterozoic in the Nubian Shield

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Acta Geochimica 2024年第1期43卷 150-173页

作者： Adel A.Surour ahmed A.Madani Mohamed A.el-Sobky Faculty of Science Galala UniversityNew Galala CitySuez 43511Egypt Department of Geology Faculty of ScienceCairo UniversityGiza 12613Egypt Egyptian Mineral Resources Authority P.O.Box 11517AbbasiyaCairoEgypt

In the south Eastern Desert of Egypt,two contrasting types of magmatism(mafic and felsic) are recorded in the Wadi Kalalat area,and form the Gabal el Motaghiarat and Gabal Batuga intrusions,*** two intrusions post-dates ophiolitic and arc associations represented by serpentinite and metagabbro-diorite,*** mafic intrusion has a basal ultramafic member represented by fresh peridotite,which is followed upward by olivine gabbro and anorthositic or *** mafic intrusion pertains to the Alaskan-type mafic-ultramafic intrusions in the Arabian-Nubian Shield(ANS)being of tholeiitic nature and emplaced in a typical arc *** the other hand,the Gabal Batuga intrusion comprises three varieties of fresh A-type granites of high K-calc alkaline nature,which is peraluminous and garnetbearing in parts.A narrow thermal aureole in the olivine gabbro of the mafic intrusion was developed due to the intrusion of the Batuga *** results in the development of a hornfelsic melagabbro variety in which the composition changed from tholeiitic to a calc-alkaline composition due to the addition of S_(i)O_(2),Al_(2)O_(3),alkalis,lithosphile elements(LILEs) such as Rb(70 ppm) and Y(28 ppm) from the felsic *** the thermal aureole,Rb amounts 2-8 ppm and Y lies in the range elieved that the Gabal Batuga felsic intrusion started to emplace during the waning stage of an arc system,with transition from the pre-collisional(i.e.,arc setting) to post-collisional and within plate *** from which the Gabal Batuga granites were fractionated is high-K calc-alkaline giving rise to a typical post-collisional A-type granite(A_(2)-subtype) indicating an origin from an underplating crustal ***,it is stressed here that the younger granites in the ANS are not exclusively post-collisional and within-plate but most likely they started to develop before closure of the arc *** possible source(s) of mafic magmas

关键词： Wadi Kalalat Gabal el Motaghairat mafic intrusion Gabal Batuga felsic intrusion Arc setting Post-collision Within-plate

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Classical taxonomy,molecular phylogeny and genetic analysis of the genus Exitianus Ball,1929(Hemiptera:Cicadellidae:Deltocephalinae)from Egypt

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Zoological Systematics 2024年第2期49卷 143-157页

作者： Rabab M.el-Hady ahmed F.el-Sayed Survey&Taxonomy Department Plant Protection Research InstituteAgriculture Research CentreGizaEgypt Microbial Genetics Department Biotechnology Research InstituteNational Research CentreGizaEgypt Egypt Center for Research and Regenerative Medicine(ECRRM) CairoEgypt

Egyptian species of the leafhopper genus Exitianus Ball,1929,***(St?l,1855),***(Distant,1908),and *** Ross,1968 are ***,morphological descriptions,and a key for their identification are *** this study,we used molecular techniques to confirm morphological identification and detect phylogeny among the three Exitianus *** partial nucleotide sequences of the amplified products obtained were determined by Macrogen *** nucleotide sequences of 28S rDNA and COX genes of the EGY-ARC-9,EGY-ARC-4,and EGY-ARC-5 were determined by Macrogen Korea,blasted into BLAST at the National Center for Biotechnology Information website(NCBI)and compared with those deposited in the GenBank DNA *** results represented the homology percentage between the partial sequences of the 28S rRNA and COX genes from each species and related species obtained from GenBank DNA *** morphological identifications of the three Exitianus species were confirmed by molecular characterization and sequencing of 28S rDNA and COX genes and identified as ***,***,and ***,their sequences of 28srDNA and COX genes were deposited in GenBank with an accession number(LC670610,LC670607,and OQ196105)for 28srDNA gene and(LC775357,LC775358,and LC775359)for the COX gene.

关键词： Auchenorrhyncha Chaismini taxonomic 28S rDNA phylogenetic

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Evaluation of urea breath test as a diagnostic tool for Helicobacter pylori infection in adult dyspeptic patients

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World Journal of Gastroenterology 2024年第17期30卷 2302-2307页

作者： Zeinab Nabil ahmed Said Asmaa Mohamed el-Nasser Department of Medical Microbiology&Immunology Faculty of Medicine for Girls Al-Azhar UniversityNasr City 11754CairoEgypt

In this editorial,we discuss the article in the World Journal of *** article conducts a meta-analysis of the diagnostic accuracy of the urea breath test(UBT),a non-invasive method for detecting Helicobacter pylori(***)infection in *** is based on radionuclide-labeled *** methods,both invasive and non-invasive,are available for diagnosing *** infection,inclu-ding endoscopy with biopsy,serology for immunoglobulin titers,stool antigen analysis,and *** guidelines recommend UBTs as the primary choice for diagnosing *** infection and for reexamining after eradication *** is used to be the first choice non-invasive test due to their high accuracy,specificity,rapid results,and ***,its performance remains unaffected by the distribution of *** in the stomach,allowing a high flow of patients to be *** its widespread use,the performance characteristics of UBT have been inconsistently described and remain incompletely *** are two UBTs available with Food and Drug Administration approval:The 13C and 14C *** tests are affordable and can provide real-time *** may prefer the 13C test because it is non-radioactive,compared to 14C which uses a radioactive isotope,especially in young children and pregnant *** there was heterogeneity among the studies regarding the diagnostic accuracy of both UBTs,13C-UBT consistently outperforms the *** makes the 13C-UBT the preferred diagnostic ***,the provided findings of the meta-analysis emphasize the significance of precise considerations when choosing urea dosage,assessment timing,and measurement techniques for both the 13C-UBT and 14C-UBT,to enhance diagnostic precision.

关键词： Helicobacter pylori Urea breath test Diagnosis Diagnostic test accuracy Meta-analysis

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The role of polymorphic cytochrome P450 gene(CYP2B6)in B-chronic lymphocytic leukemia(B-CLL)incidence and outcome among Egyptian patients

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Oncology Research 2024年第4期32卷 785-797页

作者： MENNA AL-ADL MAGDY MYOUSSEF ahmed el-SEBAIE SHERIF REFAAT AFAF el-SAID Division of Biochemistry Department of ChemistryFaculty of ScienceMansoura UniversityMansoura35511Egypt Hematology Unit Department of Clinical PathologyFaculty of MedicineMansoura UniversityMansoura35511Egypt Medical Oncology Unit Oncology Center Mansoura UniversityMansoura35511Egypt Department of Genetics Mansoura University Children’s HospitalMansoura35511Egypt

Cytochromes P450(CYPs)play a prominent role in catalyzing phase I xenobiotic biotransformation and account for about 75%of the total metabolism of commercially available drugs,including *** gene expression and enzyme activity of CYPs are variable between individuals,which subsequently leads to different patterns of susceptibility to carcinogenesis by genotoxic xenobiotics,as well as differences in the efficacy and toxicity of clinically used *** research aimed to examine the presence of the CYP2B6*9 polymorphism and its possible association with the incidence of B-CLL in Egyptian patients,as well as the clinical outcome after receiving cyclophosphamide *** was isolated from whole blood samples of 100 de novo B-CLL cases and also from 100 sex-and age-matched healthy *** presence of the CYP2B6*9(G516T)polymorphism was examined by PCR-based allele specific amplification(ASA).Patients were further indicated for receiving chemotherapy,and then they were followed *** CYP2B6*9 variant indicated a statistically significant higher risk of B-CLL under different genetic models,comprising allelic(T-allele vs.G-allele,OR=4.8,pely to achieve remission compared to those with the wild-type genotype(GG),with a response percentage of(37.5%vs.83%,respectively).In conclusion,our findings showed that the CYP2B6*9(G516T)polymorphism is associated with B-CLL susceptibility among Egyptian *** variant greatly affected the clinical outcome and can serve as a good therapeutic marker in predicting response to cyclophosphamide treatment.

关键词： B-CLL Xenobiotics Cytochromes P450 CYP2B6

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