Post-processing Mode Research Articles

Integrating low-cost GNSS and MEMS accelerometer for precise dynamic displacement monitoring

We assess the performance of the self-developed receiver coupling dual-frequency low-cost GNSS chipset and IMU MEMS sensor. The system also comprises software dedicated to vibration monitoring based on relative kinematic positioning in a post-processing mode. The observation assessment reveals high accuracy of low-cost GNSS and MEMS accelerometer data. The Septentrio Mosaic X5 chipset exhibits competitive to high-grade receivers’ phase observation noise, outperformance in code noise level and observation auto-correlation at a level that may be neglected even in high-rate applications. The evaluation of the MEMS accelerometer data proves that the sensor accuracy is adequate for vibration monitoring. With the shake table experiment, we examine the performance of vibration recovery. An advantage of the coupled solution over a GNSS-only one is documented with a 15 % reduction of the amplitude error. The backward smoothing of coupled solutions drives the next 20 % error drop. Finally, the high performance of the coupled solution based on low-cost GNSS & accelerometer is confirmed by a mean amplitude error of 0.4 mm. The frequency analyses indicate that both coupled and single-sensor solutions precisely detect the vibration frequencies; however, they also confirm the outperformance of the former over the latter. The power spectra of the recovered displacement time series accentuate the benefits of GNSS + accelerometer fusion and backward filtering for reducing displacement noise.

Design and Analysis of General Hospital Building Using STAAD Pro

Abstract: Structural design is the primary aspect of the civil engineering. The foremost basic in structural engineering is the design of simple basic components and members of a building viz., Beams, Columns and Footings. The principal objective of this project is to analyze and design a general hospital using Staad pro. The design involves manual load calculations, analysis and design of the whole structure using STAAD Pro. The design methods used in STAAD-Pro analysis are Limit State Design conforming to Indian Standard Code of Practice. Structure considered for analysis and design is 21m high hospital building located in the seismic zone III. In this project, we study the effect of various load combinations on the structure by analysing the bending moment diagrams in post processing mode. The project involves detailed drawings of column layout, column detailing and beam detailing

Effect of electropolishing on ultrasonic cavitation in hybrid post-processing of additively manufactured metal surfaces

This investigation centered on fundamental understanding of a hybrid post-processing method that synergistically combines electrochemical polishing and ultrasonic cavitation to improve the surface roughness and mechanical properties of additively manufactured parts efficiently and simultaneously in a single step. High-speed imaging was utilized to understand the effect of the DC bias applied during electropolishing on the cavitation generated at various ultrasonic amplitudes. This was aimed at validating the hypothesis that the hybrid process is characterized by more bubbles than with ultrasonic excitation alone, and, in the presence of the DC bias, the bubbles are transported from the cathode to the anode (workpiece) where their impacts cause surface hardening. High-speed imaging confirmed a higher bubble count in the hybrid process than in the cavitation-only process at different ultrasonic amplitudes. Microhardness measurements confirmed that the hybrid process yielded higher microhardness compared to cavitation peening alone, while microhardness in electrochemical polishing showed only incremental changes. This observation was also corroborated by the grain size measurements, with the hybrid process exhibiting more grain refinement than cavitation-only or electropolishing-only post-processing modes. Surface topography analysis revealed minimal improvement in surface roughness due to cavitation-only, emphasizing the importance of the hybrid process in enhancing both surface roughness and the mechanical properties. Scanning electron microscope (SEM) images showed randomly distributed micro-dimples on the surface produced by the hybrid process at the highest ultrasonic amplitude, attributed to the increased number of cavitation bubbles. This research provides fundamental insights into why the hybrid process excels in simultaneously reducing surface roughness and achieving superior surface microhardness.

ACCURACY ANALYSIS OF EGNOS POSITIONING IN FLIGHT TEST IN AIR TRANSPORT

The purpose of this publication is to determine the accuracy of EGNOS positioning in aviation using correction data from the PRN120 and PRN124 geostationary satellites. The paper compiles GPS satellite data with EGNOS corrections to determine the position of aircraft and to determine positioning accuracy. The study used research material from an airborne experiment carried out in Mielec. GNSS data were elaborated in post-processing mode in the RKTLIB software, and numerical analyses were performed in Microsoft Excel. The average accuracy of EGNOS positioning using data from the PRN120 satellite for B, L, h coordinates was 0.9 m, 0.2 m and 0.3 m, respectively. In contrast, the average accuracy of EGNOS positioning using data from the PRN124 satellite is also similarly 0.9 m, 0.2 m and 0.3 m for BLh coordinates. It was observed that the positioning accuracy at a given measurement epoch is dependent on the number of GPS satellites observed. Furthermore, in the study, the accuracy of EGNOS positioning using corrections from the PRN120 and PRN124 satellites was compared with the certification requirements of the International Civil Aviation Organisation.

Optimal Printing and Post-Processing Modes of Polymer Products Manufactured Using SLA-Technology of Additive Мanufacturing

Innovative production technologies, such as additive synthesis, is inextricably linked with the development of methods for assessing the quality of manufactured products. At the initial stage of introducing of new production methods into various industries, the most studied and widely used control methods are usually used. In most cases these are standard destructive tests. As an alternative to standard tensile tests used to evaluate the elastic and strength properties of polymer products produced using SLA-technology, the dynamic indentation method is studed in this work. Using the samples of the high-temperature photopolymer resin High Temp RS-F2-HTAM-01, the possibility of optimizing 3D printing methods and post-processing modes based on dynamic indentation data is shown. It has been shown that non-pigmented photopolymers are most susceptible to embrittlement due to their ability to transmit UV radiation into the volume of the synthesized material. It was found that the embrittlement of a polymer material has a lesser effect on the result of measuring its dynamic hardness than on its tensile strength. It has been established that post-curing of polymer products at high temperatures (up to 160 °C) and UV radiation with a power of 39 W can increase their strength and elastic modulus by 170 % and 85 %, respectively, compared to the state before treatment. It has been proven that the sensitivity of the dynamic indentation method to changes in the physical and mechanical characteristics of products obtained using SLA-technology under various types and modes of their post-processing is comparable to the sensitivity of standard tensile tests.

Using GNSS Phase Observation Residuals and Wavelet Analysis to Detect Earthquakes

Abstract Global Navigation Satellite Systems (GNSSs) are one of the techniques that can be used for the deformation monitoring caused by earthquakes. GNSSs enable the monitoring of specific areas affected by earthquakes in real-time and post-processing modes. This paper provides a novel method for the short-term displacement detection based on the phase residuals of GNSS observations. The study examines a natural earthquake from October 26, 2016, in Italy with Mw 6.1. In the proposed methodology, the residuals of the GNSS phase observations are derived using Precise Point Positioning. Then, residuals are transformed to the frequency domain using a wavelet transform, and the earthquake moment is identified using the anomalies detected in the scalogram, which do not appear in stable conditions. The described methodology allows for detecting the starting and ending moments of the earthquake. The methods described detected that the moment of the earthquake is visible in the residues 8 seconds after the seismic catalog time. The conducted experiments show that the use of signal analysis tools allows it to properly detect the ground vibrations in the residuals of GNSS phase observations and thus confirms the registration of ground vibrations in satellite observation data recorded by a GNSS receiver.

Smartphone Imaging Flow Cytometry for High-Throughput Single-Cell Analysis.

We present a portable imaging flow cytometer comprising a smartphone, a small-footprint optical framework, and a PDMS-based microfluidic device. Flow cytometric analysis is performed in a sheathless manner via elasto-inertial focusing with a custom-written Android program, integrating a graphical user interface (GUI) that provides a high degree of user control over image acquisition. The proposed system offers two different operational modes. First, "post-processing" mode enables particle/cell sizing at throughputs of up to 67 000 particles/s. Alternatively, "real-time" mode allows for integrated cell/particle classification with machine learning at throughputs of 100 particles/s. To showcase the efficacy of our platform, polystyrene particles are accurately enumerated within heterogeneous populations using the post-processing mode. In real-time mode, an open-source machine learning algorithm is deployed within a custom-developed Android application to classify samples containing cells of similar size but with different morphologies. The flow cytometer can extract high-resolution bright-field images with a spatial resolution <700 nm using the developed machine learning-based algorithm, achieving classification accuracies of 97% and 93% for Jurkat and EL4 cells, respectively. Our results confirm that the smartphone imaging flow cytometer (sIFC) is capable of both enumerating single particles in flow and identifying morphological features with high resolution and minimal hardware.

Modelling of fatigue damage in granitic rock by piezoelectric effect in quartz phase due to alternating current excitation

This paper considers numerical modelling of hypothetical fatigue damage in granitic rock by alternating current (AC) excitation of piezoelectric properties of Quartz. For this end, a numerical method consisting of a rock mineral mesostructure model, an implicit time stepping scheme to solve the piezoelectro-mechanical problem, and a fatigue damage model was developed. The rock material was assumed to be heterogenous linear elastic and isotropic, save the Quartz piezoelectric properties, which are anisotropic. An evolution equation-based continuum scalar damage model based on an evolving back stress tensor and a moving Drucker–Prager type of endurance surface was applied to compute the damage inflicted by the AC excitation. The damage was computed in a post-processed mode, i.e., un-coupled to the material model, at this stage of investigations. Some preliminary axisymmetric simulations are presented with a rock mesotructure based on electron backscatter diffraction data. These simulations corroborate the hypothesis that fatigue damage can be induced on granitic rock by converse piezoelectric effect in the Quartz phase by sinusoidal alternating current. More specifically, fatigue damage was induced on a disc-shaped numerical rock sample at a voltage of 15 kV with 2.5 kHz of frequency.

From RTK to PPP-RTK: towards real-time kinematic precise point positioning to support autonomous driving of inland waterway vessels

PPP-RTK is Precise Point Positioning (PPP) using corrections from a ground reference network, which enables single-receiver users with integer ambiguity resolution thereby improving its performance. However, most of the PPP-RTK studies are investigated and evaluated in a static situation or a post-processing mode because of the complexity of implementation in real-time practical applications. Moreover, although PPP-RTK achieves a faster convergence than PPP, it typically needs 30 s or even longer to derive high-accuracy results. We have implemented a real-time PPP-RTK approach based on undifferenced observations and State-Space Representation corrections with a fast convergence of less than 30 s to support autonomous driving of inland waterway vessels. The PPP-RTK performances and their feasibility to support autonomous driving have been evaluated and validated in a real-time inland waterway navigation. It proves the PPP-RTK approach can realize a precise positioning of less than 10 cm in horizontal with a rapid convergence. The convergence time is within 10 s after a normal bridge passing and less than 30 s after a complicated bridge passing. Moreover, the PPP-RTK approach can be extended to outside of the GNSS station network. Even if the location is 100 km away from the border of the GNSS station network, the PPP-RTK convergence time after a bridge passing is also normally less than 30 s. We have realized the first automated entry into a waterway lock for a vessel supported by PPP-RTK and taken the first step toward autonomous driving of inland vessels based on PPP-RTK.

Study of the Influence of Post-Processing Modes on the Surface Properties of Parts Manufactured Using Additive Technologies

Study of the Influence of Post-Processing Modes on the Surface Properties of Parts Manufactured Using Additive Technologies

Performance Assessment of Multi-GNSS Real-Time Products from Various Analysis Centers

The performance of real-time precise point positioning (PPP) relies primarily on the availability and quality of orbit and clock corrections. In this research, we collected data streams from 12 real-time mount points of IGS Real-Time Service (RTS) or analysis centers for a one-month period and conducted a performance assessment, including product latency and data availability, accuracy of orbit, clock and positioning performance. The epoch availability of GPS, GLONASS, Galileo and BDS was more than 98.5%, 95.79%, 94.20% and 85.9%, respectively. In addition, the orbit and clock errors of different real-time corrections was investigated. Then, PPP in static and kinematic for 16 IGS stations was conducted. The results show the real-time PPP for different products has a longer convergence time and a slightly worse accuracy than those of the post-processing PPP. For static PPP over 24 h, the real-time products of WHU had the best performance, with a mean RMSE of 1.0 cm in the horizontal and vertical directions and a median convergence time of 12.0 min. The products of CAS had the faster convergence speed due to the shortest product latency. Regarding real-time kinematic PPP for GPS only in an hourly batch, the real-time products of WHU and ESA performed best with a mean RMSE of 10.8 cm and 9.5 cm in the horizontal and vertical directions, respectively. Additionally, the PPP for different real-time products with the multi-GNSS combination obtained higher accuracy than those with GPS only in post-processing or real-time mode, and the PPP with the GPS/GLONASS/Galileo/BDS combination had the fastest convergence speed and best positioning performance. The hourly based kinematic PPP results of CAS, DLR, GFZ and WHU with the GREC combination had positioning errors smaller than 5.2 cm.

Comprehensive Evaluation of Data-Related Factors on BDS-3 B1I + B2b Real-Time PPP/INS Tightly Coupled Integration

Owing to the developments of satellite-based and network-based real-time satellite precise products, the Precise Point Positioning (PPP) technique has been applied far and wide, especially since the PPP-B2b service was provided by the third-generation BeiDou Navigation Satellite System (BDS-3). However, satellite outages during dynamic application lead to significant degradation of the accuracy and continuity of PPP. A generally used method is integrating PPP with Inertial Measurement Units (IMUs) to enhance positioning performance. Previous works on this topic are usually based on IMU data at a high sampling rate and are mostly implemented in post-processing mode. This paper will carry out a compressive assessment of the impacts of different types of precise satellite products (real-time products from the CAS, DLR, GFZ, WHU, and the final one from GFZ), Doppler observations, and different sampling rates of IMU data on the performance of the tightly coupled integration of the BDS-3 B1I/B2b and the Inertial Navigation System (INS). Results based on a group of on-board experimental data illustrate that (1) the positioning accuracy with products supplied by the CAS and WHU are roughly consistent with those using the final products; (2) the Doppler observations can effectively improve the accuracies of velocity, attitude, and vertical position at the initial epochs and during the reconvergence periods, but have invisible influences on the overall positioning, velocity, and attitude determination; and (3) the impact of IMU data interval on the performance of PPP/INS tightly coupled integration is insignificant when there are enough available satellites. However, the divergent speed of position is visibly affected by the IMU sampling rate during satellite outage periods.

Degradation of methylene blue by pulsed nanosecond discharge in Ar, O2, and N2 gaseous bubbles in water: Evaluation of direct and postprocessing modes

Dye-based water pollution is a subject of great concern as it has been linked to many health hazards. Considering their stable structures, some dyes, such as methylene blue (MB), cannot be easily removed from water. However, recent studies show that plasma-assisted processing has great potential for eliminating these dyes from water bodies. Among the different configurations of plasmas, discharges in gaseous bubbles in water are particularly promising in terms of water processing. The bubble-liquid discontinuity in such plasmas significantly facilitates the occurrence of discharge, and the modification of gas composition allows for controlling induced chemical reactions. In this study, we investigate the degradation of MB using pulsed discharges (amplitude of 20 kV, pulse duration of 500 ns, and repetition rate of 1 kHz) in Ar, O2, and N2 gaseous bubbles dispersed in water. The degradation of MB is evaluated in the direct mode, i.e., MB is present in the water during discharge as well as in the postprocessing mode, i.e., MB is added to water after plasma processing. Based on the obtained results, the most and least efficient degradation rates measured in the direct mode are achieved with O2 and N2 bubbles, respectively. Meanwhile, in the case of the postprocessing mode, degradation with N2 bubbles is initially more efficient than that with O2 or Ar. However, after hundreds of hours, higher degradation efficiency (up to 100%) is observed with O2 and Ar gas bubbles and not with N2. The findings reported herein are of great importance, particularly considering that plasma processing is complementary to the conventional techniques used in water depollution applications.

Pedestrian Trajectory Estimation Based on Foot-Mounted Inertial Navigation System for Multistory Buildings in Postprocessing Mode

Acquiring accurate and reliable pedestrian trajectories is essential for providing indoor location-based services. Although a foot-mounted inertial navigation system (Foot-INS) can acquire pedestrian trajectories in multistory buildings, it will inevitably encounter heading divergence because the constraint information is not always valid. Therefore, we proposed an accurate and convenient postprocessing indoor pedestrian positioning system (IPPS) to acquire pedestrian trajectories in multistory buildings such as shopping malls. Based on the hypotheses that the start and end points of the pedestrian trajectories on a single floor were closed, and the horizontal position of the closing point on each floor was identical. Therefore, in the single floor of multistory buildings, we use the closing point to control the trajectory drift error caused by the Foot-INS, and use a smoothing algorithm to reasonably distribute the drift error to the entire trajectory. Heading divergence is unavoidable with the Foot-INS, result in the pedestrian trajectories acquired on different floors were rotationally offset. Because pedestrian trajectories can epitomize the building orientation and provide an opportunity to align those trajectories on multistory buildings, an algorithm was proposed to match the trajectories acquired on different floors. A hybrid simulation experiment was conducted using an accurate reference object to evaluate the positioning performance of the proposed IPPS. The effectiveness of acquiring pedestrian trajectories was also confirmed by various experimental tests in a large shopping mall. The study findings suggest that the proposed IPPS is self-contained, low cost, and has the potential for large-scale applications.

Intelligent Method for Real-Time Portable EEG Artifact Annotation in Semiconstrained Environment Based on Computer Vision.

As a convenient device for observing neural activity in the natural environment, portable EEG technology (PEEGT) has an extensive prospect in expanding neuroscience research into natural applications. However, unlike in the laboratory environment, PEEGT is usually applied in a semiconstrained environment, including management and engineering, generating much more artifacts caused by the subjects' activities. Due to the limitations of existing artifacts annotation, the problem limits PEEGT to take advantage of portability and low-test cost, which is a crucial obstacle for the potential application of PEEGT in the natural environment. This paper proposes an intelligent method to identify two leading antecedent causes of EEG artifacts, participant's blinks and head movements, and annotate the time segments of artifacts in real time based on computer vision (CV). Furthermore, it changes the original postprocessing mode based on artifact signal recognition to the preprocessing mode based on artifact behavior recognition by the CV method. Through a comparative experiment with three artifacts mark operators and the CV method, we verify the effectiveness of the method, which lays a foundation for accurate artifact removal in real time in the next step. It enlightens us on how to adopt computer technology to conduct large-scale neurotesting in a natural semiconstrained environment outside the laboratory without expensive laboratory equipment or high manual costs.

Performance of global positioning system precise time and frequency transfer with integer ambiguity resolution

The Global Positioning System (GPS) carrier-phase technique is a widely used spatial tool for remote precise time and frequency transfer. However, the performance of traditional GPS time and frequency transfer has been limited because the ambiguity parameter is still the float solution. This study focuses on the performance of GPS precise time and frequency transfer with integer ambiguity resolution and discusses the corresponding mathematical model. Fractional-cycle bias (FCB) products were estimated using an ionosphere-free combination. The results show that the satellite wide-lane (WL) FCB products are stable, with a standard deviation (STD) of 0.006 cycles. The narrow-lane (NL) FCB products were estimated over 15 min with a STD of 0.020 cycles. More than 98% of the WL and NL residuals are smaller than 0.25 cycles, which helps to fix the ambiguity into integers during the time and frequency transfer. Subsequently, the performance of time transfers with integer ambiguity resolution at two time links between international laboratories was assessed in real-time and post-processing modes and compared. The results show that fixing the ambiguity into an integer in the real-time mode significantly decreases the convergence time compared with the traditional float approach. The improvement is ∼49.5%. The frequency stability of the fixed solution is notably better than that of the float solution. Improvements of 48.15% and 27.9% were determined for the IENG–USN8 and WAB2–USN8 time links, respectively.

Registration of the time dependence of the number of emission sites as a tool for analyzing field cathodes current fluctuations

A new tool for obtaining the frequency characteristics of the interaction of emission sites with adsorbates was developed. The technique is based on the use of a computerized field projector with online processing of patterns of the distribution of emission sites over the cathode surface. The resulting dependences reflect the frequency of fluctuations in the activity of individual sites. The influence of the choice of the threshold brightness parameter, the proximity of the sites to each other and the stability of the total emission current on the shape of these curves is considered. The coincidence of the shapes of curves constructed by various methods (in online mode, in post-processing mode and in the mode of random processes modeling) is analyzed. Keywords: field emission, emission current fluctuations, carbon nanotubes, registration of emission sites, adsorption processes on the surface.

Numerical analysis of G + 4 residential building with STAAD.Pro

One of the project's main goals is to use the Limit State Method with the modelling and simulation programme STAAD Pro to analyse and design a multistorey structure [G + 4 (3-dimensional frame)]. For everything from model generation to result visualisation and verification, it is the most extensively used tool among specialists in the domains of modelling, analysis, and design. The outcomes of these tests proved to be rather dependable. This is the first time a G + 4-story [2-D Frame] structure has been analysed and constructed to withstand the complete spectrum of load combinations [dead loads, live loads, wind loads, and seismic loads]. Our last job was to accurately analyse and design a G + 4 3-D RCC structure with a length of 3 m under a variety of load combinations. The structure was three metres long as well. The y-axis was constructed using G + 4 floors in this scenario. At its base, the tower was 1.5 m tall and 1.2 m wide. According to STAAD load case criteria, the structure was tested for a range of loads, including self-weight, dead load, live load, wind load, and seismic loading. STAAD. Pro produced wind load estimates based on given wind strengths at various heights while adhering to IS 875 guidelines. In addition to other important criteria, T design-related practise standards were developed. STAAD. Pro was used to analyse the structure and create the individual member components in the following stage. We may work on the structure after it has been created using post-processing mode. Using the diagrams that have been constructed, we may investigate the bending moment and shear force values. Individual members' deflection may also be monitored and recorded when they are exposed to certain loading combinations.

Relative Positioning in Remote Areas Using a GNSS Dual Frequency Smartphone.

The use of GPS positioning and navigation capabilities in mobile phones is present in our daily lives for more than a decade, but never with the centimeter level of precision that can actually be reached with several of the most recent smartphones. The introduction of the new GNSS systems (Global Navigation Satellite Systems), the European system Galileo, is opening new horizons in a wide range of areas that rely on precise georeferencing, namely the mass market smartphones apps. The constant growth of this market has brought new devices with innovative capabilities in hardware and software. The introduction of the Android 7 by Google, allowing access to the GNSS raw code and phase measurements, and the arrival of the new chip from Broadcom BCM47755 providing dual frequency in some smartphones came to revolutionize the positioning performance of these devices as never seen before. The Xiaomi Mi8 was the first smartphone to combine those features, and it is the device used in this work. It is well known that it is possible to obtain centimeter accuracy with this kind of device in relative static positioning mode with distances to a reference station up to a few tens of kilometers, which we also confirm in this paper. However, the main purpose of this work is to show that we can also get good positioning accuracy using long baselines. We used the ability of the Xiaomi Mi8 to get dual frequency code and phase raw measurements from the Galileo and GPS systems, to do relative static positioning in post-processing mode using wide baselines, of more than 100 km, to perform precise surveys. The results obtained were quite interesting with RMSE below 30 cm, showing that this type of smartphone can be easily used as a low-cost device, for georeferencing and mapping applications. This can be quite useful in remote areas where the CORS networks are not dense or even not available.

Application of different post-processing modes of dynamic contrast enhanced magnetic resonance imaging in glioma grading

Application of different post-processing modes of dynamic contrast enhanced magnetic resonance imaging in glioma grading