Separation Scheme Research Articles

Application of Linear Mixed-Effect Modeling for the Analysis of Human-in-the-Loop Simulation Experiments

A real-time human-in-the-loop (HITL) simulation is a crucial validation activity in the life cycle of air traffic management operational concept development. When planning HITL simulations, however, researchers face a series of experimental design constraints that often limit the application of advanced statistical data analyses. Linear mixed-effects modeling (LMEM) is a multiple regression analysis technique that is comparatively flexible in considering the covariance present in repeated measures data. This paper aims to make LMEM better known to applied researchers in the field of aviation research, particularly those applying HITL. For this purpose, the building steps of LMEM, the output, and model-fit tests are explained based on data obtained from an Airbus 320 flight simulation study that examined the impact of two different wake separation schemes on either a final approach or a departure path on the pilots’ perceived severity of a wake-vortex impact. The experimental setup involved six experimental factors that were not fully crossed, had an unbalanced number of repeats per pilot, and contained missing data. This prevented the use of the more traditional repeated measures analysis of variance. The LMEM was able to handle this and could explicitly test the study hypotheses with statistical confidence.

Optimizing and designing upper-stage separation spring of lifting-body rocket

Because the upper-stage separation of a lifting-body rocket is difficult under the low-altitude and high-speed flight environments, an upper-stage separation scheme based on the separation spring is proposed. The integration of ADAMS and MATLAB realizes the multi-body dynamics simulation analysis of upper-stage separation. The experimental design method is used to carry out the target simulation and calculation of the upper-stage separation process, with the separation condition deviation and the separation spring deviation considered at the same time, thus ensuring the reliability of the separation scheme. In order to further optimize the separation scheme, an upper-stage separation optimization model is established with the Isight software, and the mass of separation spring is optimized with the multi-island genetic algorithm and significantly reduced by 48.87% under the condition that the upper-stage separation process satisfies all constraints, thereby effectively improving the performance of the lifting-body rocket.

Investigation of Transition Flow on Suction Surface of Highly Loaded Compressor Cascade Controlled by Plasma Actuator

A practical method for improving the performance of highly loaded compressor cascades is to delay the onset of transition. Plasma actuators are used on the suction surface to manage the transition from laminar to turbulent by injecting momentum into the boundary layer. An experimental study was conducted in a low-speed wind tunnel to validate the actuator's control capability and the numerical simulation model. Both experimental and numerical results show that actuators located at various positions can improve the performance of the cascade and reduce flow loss to varying degrees. The most effective method is to place the actuator upstream of the separation bubble to delay the onset of the transition from laminar to turbulent flow, which results in a 6.32% decrease in total pressure loss and a 2.5% increase in static pressure rise. The control scheme at the transition position restores laminar flow locally, causing a secondary transition. However, it has the lowest control capability due to the dissipation of the actuator momentum. The downstream control scheme only suppresses the degree of turbulent separation without delaying laminar separation, resulting in weaker control effectiveness compared to the upstream laminar separation scheme. The study also examined the interaction between the plasma actuator on the suction surface and the flow in the endwall region, which showed that the accumulation of low-energy fluid in the corner region increases, resulting in a slight elevation of shear losses between the midspan boundary layer and the corner region.

Improved sliding mode tracking control for spacecraft electromagnetic separation supporting on-orbit assembly

This paper addresses the electromagnetic separation problem for mass-unknown spacecraft in elliptical orbits that play a significant role in on-orbit assembly and other future space missions. First, the relative motion dynamics model between the platform (target spacecraft) and module (chaser spacecraft) is presented with the lumped disturbance resulting from external disturbances, elliptical eccentricity and unknown mass, and a compliant reference trajectory is designed by applying the idea of trigonometric-function. Then, an improved sliding mode controller is developed to ensure that the tracking errors of relative motion can converge to near the equilibrium point. In order to avoid adverse impacts, the elliptical eccentricity and unknown mass are fully considered by using the developed control approach, and the global asymptotic stability of the closed-loop system is analyzed by strict theoretical proof. Combined with spacecraft electromagnetic docking technology, the electromagnetic separation scheme can make on-orbit assembly easy to achieve with certain advantages, e.g., it doesn’t consume propellant and thus doesn’t cause plume contamination, and has reversible, continuous and non-contact characteristics. Finally, numerical simulations are performed to illustrate the effectiveness and feasibility of the developed control approach.

Parametric reduced-order modeling for component-oriented treatment and localized nonlinear feature inclusion

We propose coupling a physics-based reduction framework with a suited response decomposition technique to derive a component-oriented reduction (COR) approach, which is suitable for assembly systems featuring localized nonlinearities. Dependencies on influencing parameters are injected into the reduced-order model (ROM), thus ensuring robustness and validity over a domain of parametric inputs, while capturing nonlinear effects. The implemented approach employs individual component modes to capture localized features while additionally relying on reduced modes of a global nature to approximate the system’s dynamics accurately. The global modes are derived from a linear monolithic system, defined as a result of a coordinate separation scheme, which permits the proposed COR-ROM to naturally couple the response between linear and nonlinear subdomains. The derived low-order representation utilizes a proper orthogonal decomposition projection and is additionally reinforced with the inclusion of a hyper-reduction technique to capture the underlying high-fidelity model response while providing accelerated computations. The resulting approach is exemplified in the synthetic case studies of a four-story shear frame with multiple nonlinear regions driven by hysteresis and a large-scale kingpin connection featuring plasticity.

Fourteen Years of Energetic Neutral Atom Observations from IBEX

The Interstellar Boundary Explorer (IBEX) has been observing the outer heliosphere and its interactions with the very local interstellar medium (VLISM) via measurements of energetic neutral atoms (ENAs) for over 14 yr. We discovered the IBEX Ribbon—a structure completely unanticipated by any prior theory or model—that almost certainly resides beyond the heliopause in the VLISM. We also characterized the other major source of heliospheric ENAs, the globally distributed flux (GDF), produced largely in the heliosheath between the termination shock and heliopause. In this study, we make three major new contributions. First, we validate, provide, and analyze the most recent 3 yr of IBEX-Hi (0.5–6 keV FWHM) data (2020–2022) for the first time. Second, we link these observations to the prior 11 yr of observations, exploring long-term variations. Finally, we provide the first IBEX team-validated Ribbon/GDF separation scheme and separated maps. Because of the uncertainty in separating different line-of-sight integrated sources, we provide not just best guess (median) maps, but also maps with upper and lower reasonable values of Ribbon and GDF fluxes, along with bounding fluxes that add the uncertainties to the upper and lower values. This allows theories and models to be compared with a range of possible values that the IBEX team believes are consistent with data. These observations, along with the reanalysis of the prior 11 yr of IBEX-Hi data, provide new insights and even further develop our detailed understanding of the heliosphere’s interaction with the local interstellar medium unlocked by IBEX.

Joint Task and Data-Oriented Semantic Communications: A Deep Separate Source-Channel Coding Scheme

Joint Task and Data-Oriented Semantic Communications: A Deep Separate Source-Channel Coding Scheme

Benchmarking the accuracy of the separable resolution of the identity approach for correlated methods in the numeric atom-centered orbitals framework.

Four-center two-electron Coulomb integrals routinely appear in electronic structure algorithms. The resolution-of-the-identity (RI) is a popular technique to reduce the computational cost for the numerical evaluation of these integrals in localized basis-sets codes. Recently, Duchemin and Blase proposed a separable RI scheme [J. Chem. Phys. 150, 174120 (2019)], which preserves the accuracy of the standard global RI method with the Coulomb metric and permits the formulation of cubic-scaling random phase approximation (RPA) and GW approaches. Here, we present the implementation of a separable RI scheme within an all-electron numeric atom-centered orbital framework. We present comprehensive benchmark results using the Thiel and the GW100 test set. Our benchmarks include atomization energies from Hartree-Fock, second-order Møller-Plesset (MP2), coupled-cluster singles and doubles, RPA, and renormalized second-order perturbation theory, as well as quasiparticle energies from GW. We found that the separable RI approach reproduces RI-free HF calculations within 9meV and MP2 calculations within 1meV. We have confirmed that the separable RI error is independent of the system size by including disordered carbon clusters up to 116 atoms in our benchmarks.

Frequency-dependent impairment calibration and estimation for a 96 GBaud coherent optical transceiver

For 800 Gbps/λ and beyond optical transmission systems, frequency-dependent impairments (FDI) degrade coherent optical transceiver (CO-TRx) performance severely. Calibration and compensation of such FDI in factories includes amplitude/phase frequency response (AFR/PFR), skew, and ripple for both transmitters(Tx) and receivers (Rx). However, due to the polarization rotation and phase rotation effects in optical link, the separation and extraction of FDI from different polarization or I/Q tributaries is challenging. Here we report a FDI calibration method based on orthogonal separation scheme and frequency domain analysis. The proposal can simultaneously characterize and separate the Tx/Rx sides FDI including AFR, PFR, and time skew of four tributaries. Finally, the effectiveness is demonstrated by transmitting a 96 GBuad Nyquist-16QAM signal on a 64 GBaud-class CO-TRx.

Optimization of preparation and transformation of protoplasts from Populus simonii × P. nigra leaves and subcellular localization of the major latex protein 328 (MLP328)

BackgroundPopulus simonii × P. nigra is an ideal material for studying the molecular mechanisms of woody plants. In recent years, research on Populus simonii × P. nigra has increasingly focused on the application of transgenic technology to improve salt tolerance. However, the rapid characterization of gene functions has been hampered by the long growth cycle and exceedingly poor transformation efficiency. Protoplasts are an important tool for plant gene engineering, which can assist with challenging genetic transformation and the protracted growth cycle of Populus simonii × P. nigra. This study established an optimized system for the preparation and transformation of protoplasts from Populus simonii × P. nigra leaves, making genetic research on Populus simonii × P. nigra faster and more convenient. Major Latex Protein (MLP) family genes play a crucial role in plant salt stress response. In the previous study, we discovered that PsnMLP328 can be induced by salt treatment, which suggested that this gene may be involved in response to salt stress. Protein localization is a suggestion for its function. Therefore, we conducted subcellular localization analysis using protoplasts of Populus simonii × P. nigra to study the function of the PsnMLP328 gene preliminarily.ResultsThis study established an optimized system for the preparation and transformation of Populus simonii × P. nigra protoplasts. The research results indicate that the optimal separation scheme for the protoplasts of Populus simonii × P. nigra leaves included 2.5% cellulase R-10, 0.6% macerozyme R-10, 0.3% pectolyase Y-23, and 0.8 M mannitol. After enzymatic digestion for 5 h, the yield of obtained protoplasts could reach up to 2 × 107 protoplasts/gFW, with a high viability of 98%. We carried out the subcellular localization analysis based on the optimized transient transformation system, and the results indicated that the MLP328 protein is localized in the nucleus and cytoplasm; thereby proving the effectiveness of the transformation system.ConclusionIn summary, this study successfully established an efficient system for preparing and transforming leaf protoplasts of Populus simonii × P. nigra, laying the foundation for future research on gene function and expression of Populus simonii × P. nigra.

Experimental and numerical investigation on the unsteady interaction in longitudinal stage separation for parallel-staged two-body configuration

Hypersonic stage separation is a significant process, probably involving complex aerodynamic interaction, which determines the survival of two-stage-to-orbit (TSTO) vehicles. The longitudinal stage separation (LSS) scheme is proposed to improve the safety of the parallel-staged TSTO vehicle, where a small interstage gap may result in weak interference. Therefore, an experimental and numerical study of LSS for the parallel-staged TSTO vehicle at Mach 7 with different angles of attack (AoA) is carried out. The dynamic interaction, including variations in the shock structure, wall pressure distribution, and unsteady aerodynamics, is investigated by testing and numerical simulation. The LSS experiments for the TSTO vehicle were performed using a high-speed pneumatic ejection launch system in the JF-12 shock tunnel, and the method was developed using high-speed visualization and image processing techniques to capture the separating trajectory. The numerical simulations were carried out using the overset grid method and solving the Navier–Stokes equations coupled with the rigid body dynamics equations to obtain the laminar flows over the TSTO vehicle during LSS. The qualitative and quantitative comparison of the test and numerical results showed good agreement in terms of aerodynamic performance, flowfield pattern, wall pressure, and separation trajectory. They show that the small interstage gap of the LSS leads to weak type I and VI shock–shock interactions, with short-duration weak shock reflection at a higher AoA. Furthermore, no shock reflection or interstage gap is observed at lower AoA. Moreover, no stage recontact is observed, and the safety and feasibility of LSS for parallel-staged TSTO vehicles are demonstrated.

Improved MIMO-SAR Echo Separation Scheme With Constrained/Generalized LASSO Regression: New Insights and Applications

Improved MIMO-SAR Echo Separation Scheme With Constrained/Generalized LASSO Regression: New Insights and Applications

A Transmit-Receive Separation Scheme of Monopulse Antenna Applied in the Terahertz Band

A Transmit-Receive Separation Scheme of Monopulse Antenna Applied in the Terahertz Band

Design and Implementation of a Mobile Experimental Application for Networked Control Systems

With the development of mobile technologies, mobile applications are increasingly designed and developed. In the field of science, technology, engineering, and mathematics (STEM) education, the idea of using mobile devices for teaching and learning has gradually gained popularity and gained in-depth research. Owing to the advantages of convenience, portability and excellent interactive abilities, mobile devices are a good choice for accessing remote laboratories. In propose of promoting the massive online experimentation of control education, a mobile application with framework based on React-Native is implemented in this paper. The overall remote laboratory architecture adopts front-end and back-end separation scheme, which benefits the mobile application focusing on the construction of front-end interface and user experience. Various functional modules and technologies are applied in the mobile application, allowing users to access various experiment test rigs in the remote laboratory with intuitive experimental immersion. Moreover, a complete laboratory management system to manage the massive users from different universities has also been integrated into the mobile application. At the end, a remote networked control experiment has been conducted to prove the practicability of the mobile application.

Demonstration of MIMO-SAR Echo Separation Scheme for Improved OFDM Waveforms With Airborne X-Band DBF-SAR

Demonstration of MIMO-SAR Echo Separation Scheme for Improved OFDM Waveforms With Airborne X-Band DBF-SAR

Evaluation Of The Implementation Of Traffic Separation Scheme (TSS) In The Sunda Strait

The sea traffic separation chart or what is commonly called the Traffic Separation Scheme (TSS) is generally used to assist international shipping navigation and is also part of a country’s maritime zone as mandated in UNCLOS 1982. In this case, Indonesia has implemented TSS in the Sunda Strait and in the Lombok Strait on 1 July 2020. The Directorate General of Sea Transportation, the Ministry of Transportation is the leading agency responsible for enforcement of the scheme through the Directorate of Navigation and the Directorate has established the Merak Vessel Traffic Service (VTS) system in the Province of Banten to monitor the Sunda Strait and VTS Benoa in the Province of Bali to monitor the Lombok Strait. Since the implementation of the TSS in the Sunda Strait until now, it turns out that there are still many ships that do not comply with the traffic procedures in the TSS as regulated in such a way. The research suggestion that violations in addition to administrative sanctions for those ships who commit violations, also implement a violation reporting system application to speed up the process of reports from VTS Operators to related officials.

Detection of Cyber Attacks in Modern Renewable Integrated Power Sector: A Matrix Separation Scheme

Detection of Cyber Attacks in Modern Renewable Integrated Power Sector: A Matrix Separation Scheme

An Improved Echo Separation Scheme With OFDM Chirp Waveforms for Spaceborne MIMO SAR

An Improved Echo Separation Scheme With OFDM Chirp Waveforms for Spaceborne MIMO SAR

High-precision Sm isotope analysis by thermal ionisation mass spectrometry for large meteorite samples (>1 g).

This study presents a new procedure for high-precision Sm isotope analysis by thermal ionisation mass spectrometry (TIMS) for geological samples. A four-step chemical separation scheme results in sharp separation of Sm and Nd from the same sample aliquot. The first step utilises anion exchange resin to remove Fe from the sample solution. Two different liquid-liquid extraction resins are then used to isolate rare-earth elements (TRU-Spec) and purify Sm from Nd (DGA). Fractionation occurs on the DGA resin due to the nuclear field shift effect, but this is negligible if yields greater than 70% are achieved. Different analytical setups were tested to ascertain their ionisation efficiencies on TIMS. The effect of activators composed of Pt and Ta was tested on single Re filaments but the conventional double Re filament assembly provided efficient ionisation and more stable ion beams. The determination of nucleosynthetic isotope variations requires high precision for all Sm isotope ratios. We aimed to improve the precision on the scarce 144Sm isotope (3% of all Sm). Static, multistatic and dynamic methods were tested. Isotope ratios were normalised to both 147Sm/152Sm and 152Sm/148Sm for comparison. The dynamic methods failed to provide better precision on ratios involving 144Sm, whereas the multistatic method yielded improved precisions between 13 and 22 ppm (twice the standard deviation, 2 SD) on the 144Sm/152Sm ratio. Synthetic standards have variable Sm isotope compositions, thus requiring systematic and precise characterisation against terrestrial samples. Analyses conducted using this new procedure yielded high-precision values which were consistent with literature data for an array of terrestrial rock standards and the meteorite Allende.

Assessment and Rehabilitation of Damaged Buildings in Historic Benghazi City

The primary focus of the study is to assess and classify the damage in the old Benghazi City. Specifically, it aims to evaluate buildings within a designated area, which is bordered by Omar Ibn Al-Aas Street to the south, Omar Al-Mukhtar Street to the north, Ben Issa Street to the east, and the extension of Gamal Abdel Nasser Street to the west. The main objective is to gather valuable insights and data that can support effective rehabilitation or reconstruction efforts. By comprehending the extent of the damage and categorizing it accordingly, the study seeks to provide essential information for decision-making processes and determine the most appropriate approach for restoration. The ultimate aim is to ensure the safe return of residents to the affected area. In addition to this, the restoration process aims to preserve and revitalize the city' s religious, historical, and distinctive features. This includes safeguarding religious structures, landmarks, and elements that contribute to the city' s unique identity. To achieve this, the study proposes separate rehabilitation schemes tailored for ordinary buildings and historic buildings.