Instrument Landing Research Articles

Optimized phasing conditions to avoid edge mode excitation by ICRH antennas

An ion cyclotron resonance heating (ICRH) antenna system must launch radio frequency (RF) power with a wavenumber spectrum which maximizes the coupling to the plasma. It should also ensure good absorption while minimizing the wave interaction with the plasma edge. Such interactions lead to impurity release, whose effect has been measured far from the antenna location (Klepper et al. 2013; Wukitch et al. 2017; Perkins et al. 2019) and can involve the entire scrape-off layer. In the normal heating scenario, for which the frequency of the waves launched by the antenna is larger than the ion cyclotron frequency of the majority ions $\omega > \omega _{\textrm {ci},\textrm {maj}}$ , release of impurities due to ICRH can be affected by minimizing the low $|k_{\parallel }| < k_0$ power spectrum components of the antenna. Impurity release can be the result of low central absorption of the waves or power transfer from the fast to the slow wave due to the presence of a confluence in the plasma edge. In ASDEX Upgrade (AUG), a reduction of heavy impurity release by ICRH in the plasma was qualitatively well correlated to the parallel electric field and RF currents flowing around the antenna (Bobkov et al. 2017). In this article, we first show a correlation between the reduction in impurity release by ICRH in AUG and the rejection of the low $|k_{\parallel }| < k_0$ region of the antenna power spectrum. We show that the same correlation holds for results obtained in the Alcator C-Mod tokamak. Finally, using this idea, we reproduce ICRH induced impurity release behaviour in a not yet published experiments of JET, and make predictions for ITER and DEMO.

Алгоритм директорного управления самолетом в режиме посадки

The director control mode is an integral part of all modern aircraft, i.e. civil, military, transport and even unmanned aerial vehicles. The paper describes the experience of developing, implementing and perfecting the directorial control algorithm in the landing mode as applied to small aircraft DA-42-T and L-410 during flight tests. As the basic algorithm, the algorithm “Deviation allowance” is used. The satellite navigation system, i.e. GPS / GLONASS without differential correction, was selected as the main data source for the approach. This solution allows for semi-automatic landing at an unequipped airfield, but is inferior in accuracy to instrument landing, e.g. ILS, RSBN. According to the results of flight tests, we assessed the accuracy and found that the developed algorithm allows landing in accordance with the 1st category of ICAO.

회전익 드론 접촉식 충전스테이션 도킹을 위한 딥러닝 기반 자동착륙시스템 구현

회전익 드론 접촉식 충전스테이션 도킹을 위한 딥러닝 기반 자동착륙시스템 구현

A Parallel FDTD/ADI-PE Method for Ultralarge-Scale Propagation Modeling of ILS Signal Analysis

In this letter, we propose a high-accuracy low-cost hybrid finite-difference time-domain (FDTD)/alternating-direction-implicit parabolic equation (ADI-PE) method for ultralarge-scale electromagnetic simulation on a distributed computing platform. The hybrid method offers fast and precise 3-D deterministic radio-wave propagation predictions in a difficult-terrain scenario with specific detailed structures in both near field and far field. Since the typical parallel ADI-PE method suffers from high-frequency data communication between different calculation cores, which greatly discount simulation efficiency in bandwidth-constrained environments, we adopt a Woodbury-formula-based parallel algorithm to find inverse matrixes of tridiagonal matrixes so that implicit and explicit steps of the PE can be finished in local computing cores. Simulation results for the instrument landing system (ILS) demonstrate the capability of the proposed method in achieving the state-of-the-art performance.

Land costs, government intervention, and migration of firms: The case of China

By using unique firm relocation data in China, we first document the relocation behavior of Chinese firms and show that less government intervention (relative to market forces) can improve economic efficiency by facilitating industrial relocation which saves on costs. Ever since China joined the World Trade Organization (WTO) in 2001, investments have poured into the coastal region, which in turn, have almost tripled land costs in the major coastal cities. We exploit this land cost shock in the early 2000s to identify its effect on the relocation behavior of firms. Specifically, we instrument land price growth with the access of a city to foreign markets (approximated by distance to Shanghai), and then estimate the differential impact of land costs on firms regarding land reliance. Our major findings are as follows: (1) the migration rate of Chinese firms in China is on average 3.2%, (2) Rising land costs drive firms to migrate, and firms that use more land-intensive technology are more compelled to migrate, and (3) in regions where the local government intervention is stronger (the market is less developed), the relocation decision of Chinese firms is distorted in the sense that firms are less likely to relocate despite surging land prices due to government intervention.

Spatial Disorientation Impact on the Precise Approach in Simulated Flight.

BACKGROUND: The risks posed by flight illusions impacting pilot spatial orientation have been determined as a safety concern from numerous past aviation accident investigations. Early demonstration of the adverse effects of flight illusions on spatial orientation would be desirable for all pilots, especially at the early training stages to deeply embed good practices for onset detection, flight correction, and response mitigation.METHOD: Simulated flights on a disorientation demonstrator were performed by 19 pilots for 3 conditions: no illusion, somatogyral illusion, and Coriolis illusion. An objective approach for assessing pilot performance degradation due to flight illusions can be done by using a defined flight profile: instrument landing system (ILS) flight trajectory during final instrument approach. Deviations to the standard ILS profile were recorded to measure and evaluate the influence of the demonstrated flight illusion on pilot performance.RESULTS: The results show the expectation that the smallest deviations from the ideal trajectory are caused by pilot tracking error (no illusion), and the greatest deviations are caused by the Coriolis illusion. Results demonstrated a statistically significant effect of illusions on performance. According to statements from pilots, training for flight illusion response is essential to complement training in aircraft regulations and aerodynamics.DISCUSSION: Measuring the influence of vestibular illusions on flight profile with a simulator allows assessment of individual differences and improvement of pilot performance under the conditions of no illusion, the somatogyral illusion, and the Coriolis illusion.Boril J, Smrz V, Blasch E, Lone M. Spatial disorientation impact on the precise approach in simulated flight. Aerosp Med Hum Perform. 2020; 91(10):767775.

Adaptive fault-tolerant control for carrier-based UAV with actuator failures

An adaptive fault-tolerant control (AFTC)1 method is developed for an automatic carrier landing system (ACLS)2 with actuator failures. First, an actuator fault model is added to the linear unmanned aerial vehicle (UAV)3 model. Then, an AFTC algorithm based on the output feedback designs for output tracking is raised to solve the theoretical problem extracted through the practical automatic carrier landing process. The σ-modification based robust adaptive update law is used for both parameterized and unparameterized fault. Then the stability of the system is verified by Lyapunov function method. Finally, the ACLS simulation is conducted, which includes the guidance law designed by PID method, the flight controller designed by the proposed AFTC method and a deck motion prediction and compensation based on auto-regression (AR)4 model. The comparison result shows that the improved robust AFTC can effectively deal with both parameterized and unparameterized fault, as well as external disturbances.

Workload benefits of colour coded head-up flight symbology during high workload flight

The manipulation of colour in display symbology design has been recognised as a method to improve operator experience and performance. An earlier paper by the authors demonstrated that redundantly colour coding head-up flight symbology supported the manual flying performance of both professional and non-professional pilots during low-workload flying scenarios. In this study the workload and performance of 12 professional airline pilots was evaluated in high workload conditions whilst they flew manoeuvres and an instrument landing system (ILS) approach with and without the presence of colour feedback on a head up display (HUD). Workload was manipulated by presenting pilots with a concurrent auditory n-back task. Colour coded flight symbology reduced the subjective workload of the pilots during high workload conditions. In contrast, manual flying performance during high workload was not improved by the presence of colour coded feedback.

Methodic aspects of aircraft glide slope correction for prevention of CFIT category accidents during pre-landing descent

Aviation accidents of the category of controlled flight into terrain in world commercial aviation are included into three "killers" in aviation together with loss of control in flight (LOC-I) and runway excursions (RE). As a result of long-term research of this problem the methods of CFIT risk level reduction, pilot training and retraining programs were developed and put into practice. Also several generations of onboard ground proximity or obstacle warning systems were created (GPWS, EGPWS, TAWS), the disadvantage of which is a passive – advisory type of warnings. The conclusions of the commissions concerning the results of aviation accidents investigations indicate the cases of crew disregard of an alarm of a ground proximity warning system and possibility of a go-around procedure to make a missed approach. Despite the aviation community actions, accidents of this category continue to occur. Therefore, search of new methods and solutions of the controlled flight into terrain problem is necessary. One of the possible ways to resolve this problem is making proximity warning systems active and two-mode operative. The first one is some type of warning to the crew about approaching the boundaries of a safe maneuvering area during approach to land as well as the recommendations to avoid a glide path deviation. The second way is that if the crew members don`t take any actions with a warning on or crew actions are not effective enough, it is necessary to regain a glide slope with temporary pilot disengagement from a control loop.

Research on Ship to Ship Channel Characteristics Based on Effect of Antenna Location in Inland Waterway at 5.9 GHz

Research on Ship to Ship Channel Characteristics Based on Effect of Antenna Location in Inland Waterway at 5.9 GHz

A Study on Precise Positioning for an Electric Vehicle Wireless Power Transfer System Using a Ferrite Antenna

In the last decade, engineers from automotive manufacturers and charging infrastructure suppliers have widely studied the application of wireless power transfer (WPT) technology to electric vehicles. Since this time, engineers from automotive manufacturers have studied precise positioning methods suitable for WPT using methods such as mechanical, communication-based or video-based. However, due to high costs, electromagnetic interference and environmental factors, the experts of the SAE J2954 was focused on the WPT’s precise positioning method by ferrite antennas and low power excitation. In this study, we present how to use the ferrite antennas to find a central alignment point between the primary and secondary units within the alignment tolerance area that requires the minimum power transfer efficiency of the EV WPT system. First, we analyze the ferrite antenna already applied in the automotive and verifies whether it is suitable for the precise positioning of the WPT system for EV. We use modeling and simulation to show that it is necessary to calculate all induced loop voltages in the relationship between incident magnetic field signal strength and induced loop voltage because of the short distance between the transmitter and receiver of the ferrite antenna in WPT. In addition, we also suggest a sequence to find the fitting location of the ferrite antenna, the number of antennas used and the center alignment point. After the simulation is performed on the suggestions, component-level and vehicle-level tests were conducted to verify the validity of the simulation results. As a result, it is shown that a ferrite antenna is suitable as a method for the secondary device to find the center alignment point of the primary device.

Genetic algorithm for biobjective optimization of indoor LTE femtocell deployment

SummaryThe optimization of indoor femtocell base stations (FBS) placement is a highly complex problem in which multiple performance figures can be considered. In this paper, we propose a biobjective optimization approach based on non‐dominated sorting genetic algorithm II (NSGA‐II) to solve the indoor FBS deployment problem in residential scenarios where a single cell is deployed within the coverage of a single dominant interfering external macro base station (MBS). The optimization problem is formulated with the objective of jointly minimizing outage probability and maximizing normalized downlink average throughput. Several conditions are simultaneously considered under the framework of Monte Carlo simulations, such as the effect of co‐channel interference in uplink and downlink, buildings with arbitrary layouts, realistic transmission schemes and antenna radiation patterns, random user distributions, and a well‐established empirical path loss model. The proposed algorithm, which determines the location and orientation of the FBS's antenna that provides a suitable compromise between the two objective functions, is evaluated in this paper. First, two different experiments are proposed to investigate the algorithm convergence; then, statistical analyses are formulated to characterize the relation between the values achieved for both objective functions; finally, the computational load is evaluated. Results indicate the convergence of the proposed method towards the real Pareto front and a significant reduction of the computational time with respect to a reference method based on exhaustive search, while pointing at new criteria for the selection of the objective functions.

Investigating Untapped Capacity at Single-Runway Airports using Short Final Curved Approach, Dual Glide Slope, and Double Threshold

In Europe more than one third of the 100 busiest airports have only one runway and most of them have no possibility to build another one. Aircraft of all types and sizes must use that same runway which affects operational complexity. In such situations the problem of capacity appears since separation between aircraft is based on all of them following the same path and smaller aircraft following larger ones have to wait for the wake vortex to dissipate, in the case of both arrivals and departures. This paper offers a possible concept for increasing single-runway airport landing capacity. It is based on separating smaller aircraft to a final approach path that is not affected by the wake vortices produced by the larger aircraft. Published references dealing with this topic are included and discussed. The operation rules proposed are based on existing standards and some best practices. This paper does not discuss available technological solutions.

Research on TCH and RDH of Glide Path Equipment

There is a certain difference between the RDH obtained from the flight inspection and the TCH calculated from geometry terrain. The problem is always neglected and someone attribute the cause of poor RDH to equipment issues, actually equipment is a problem, but the electromagnetic environment is also a very important factor overlooked by owner. When the electromagnetic environment around glide path antenna is worse, the difference of TCH and RDH is even larger, and even cannot meet the requirements for safe operation. This article study the calculation method of the actual measured RDH, revealing fundamental reason of the difference, and further explaining the importance of protecting the electromagnetic environment of the instrument landing system,.providing analysis ideas and solutions for equipment construction and maintenance engineers.

Anomalous Propagation of Radio Waves from Distant ILS Localizers Due to Ionospheric Sporadic‐E

AbstractThe ionospheric sporadic‐E (Es) layer occasionally causes anomalous propagation (AP) of VHF radio waves to distant locations. This effect, EsAP, may cause interference to VHF radio operation above 100 MHz. Recent study showed that VHF air navigation signals from distant stations are frequently observed when Es occurs. The observed frequencies includes channels of VHF omnidirectional radio range (VOR) and instrument landing system localizer (ILS LOC). The study showed that EsAP signals can be very strong and frequently exceeded the allowable interference limit of navigation receivers. In this paper, we focus on EsAP on ILS LOC channels using the data obtained in the previous study. A series of extremely strong signals was observed on an ILS LOC frequency at Kure, Japan, on 15 May 2014 when an ionosphere sounder observed high‐density Es. The source of the signal was identified as an ILS LOC‐type direction aid (LDA) at Hualien, Taiwan. During the same period, several EsAP signals were observed on other ILS LOC channels, but their strengths were less significant. Analysis showed the causes of the strong signal from Hualien LDA: (1) the center of the narrow radio beam passed through the region very close to the receiver site; (2) the elevation angle of the propagation path was very close to that of the actual beam center. Statistics showed that there were several outstanding EsAP events of which source was Hualien LDA. This study suggests that if similar conditions exist, radio interference to ILS LOC receiver can happen on any ILS LOC channels.

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The main features of an efficiency evaluation of positional (stationary and autonomous) sonar systems at the design stage and deciding on the coordinates of the antenna installation site based on modeling and visualization of the expected surveillance zones using intelligent geographic information systems are considered in the paper. The issues of intellectual decision support for the rational spatial distribution of receiving antennas are considered. The influence of the information support quality of geographic information systems on the calculations accuracy of expected surveillance zones of the sonar systems under the various hydrological and acoustic conditions is assessed. A new performance indicator in the form of spatial volume of the expected surveillance zone is proposed. A method for solving the optimization problem of finding the maximum volume of the illuminated space as a coordinates function of the antenna placement within a given observation area, with fixed technical characteristics of the monitoring system and given noise conditions, acoustic characteristics of the detection object and the observation time has been developed. The proposed approach to selecting the rational variant of the receiving antennas location of positional hydroacoustic facilities and systems in the interests of dispatching geospatial processes using as a mean of intelligent support the modern hardware and software complex realizing the specified selection by such efficiency indicator as volume of illuminated space, in the conditions of a two-dimensionally inhomogeneous model of medium, close to real hydrological-acoustic conditions, allows to increase the accuracy of assessing the illumination efficiency of underwater environment of positional hydroacoustic means and systems and significantly reduce the design and development time as compared with the traditional approach, requiring expensive field observation over a long period of time.

MIMO Radar Array Configuration with Enhanced Degrees of Freedom and Increased Array Aperture

This paper presents a new antenna array design approach for multiple-input multiple-output (MIMO) radar. The geometry exhibits increased degrees of freedom (DOFs) with precise antenna locations for direction-of-arrival (DOA) estimation of sources. The enhancement is realized by using the method of sum coarray of the difference coarray (SCDC). By effectively increasing the inter-element spacing of the transmitting array, a larger hole-free SCDC uniform linear array (ULA) is obtained. This increment provides more DOFs and extended virtual array aperture (VAA) for intended geometry. The transmitting and receiving sensor positions are based on the maximum inter-element spacing constraint (MISC) principle. The MISC composition involves three sparse ULAs with two separate antennas placed appropriately. The mathematical expressions are presented to validate the designed model. Moreover, arbitrary and optimized antenna scenarios for the transmitter and receiver are investigated in terms of DOFs and VAA. The advantages of the proposed configuration are demonstrated by conducting rigorous Monte Carlo simulations. The experimental results of DOFs, VAA, number of resolvable sources, Cram $$\acute{\hbox {e}}$$ r–Rao bound performance, detection, and resolution ability reveal that the proposed sensor array design approach is suitable for MIMO radar which is also capable of estimating the DOAs of multiple sources efficiently in underdetermined scenarios.

Optimal antenna locations of the VLBI Global Observing System for the estimation of Earth orientation parameters

To support monitoring subtle effects in the Earth system such as a mean sea level rise of 3 mm/year, a next-generation VLBI system, the VLBI Global Observing System (VGOS), has been developed and a new VGOS station network is being built. However, the geometry of the current VGOS network and its planned extension suffer from a lack of stations in the southern hemisphere. In this investigation, we identify optimal locations for additional VGOS radio telescopes with a new method based on bulk observing schedule generation and subsequent large-scale Monte-Carlo simulations. The location of the additional station is varied over 477 possible locations, homogeneously distributed over land areas on the globe. For each antenna location, several schedules have been generated and simulated to minimize the effects of scheduling and the randomness of simulations. Thereby, it is possible to judge, in which regions an additional VGOS station would have the biggest impact on the precision of the estimated geodetic parameters, in our case assessed by the repeatabilities of the estimated Earth orientation parameters (EOPs). To generate highly optimized schedules and to remove effects due to non-optimized scheduling, a total of 93 thousand schedules were iteratively generated, investigating over 300 billion scans and 2.4 trillion observations. Each schedule was further simulated 1000 times, leading to over 5 trillion simulated and analyzed observations. Although the optimum location of a future VLBI station depends on the EOP of interest and the geometry of the existing network, it is shown that the more the VGOS network grows, the more the lack of southern stations becomes prominent. The best location for an additional VGOS station for most EOP components and especially in the case of future VGOS networks would be the southern part of South America. It is further shown that the location of the additional antenna highly determines the expectable precision of the EOP estimates. For a 6-station network, the location of an additional seventh antenna can improve the precision of the EOP by a factor of 2.4 to 3.8. For an 18-station network, the location of an additional 19th station still improves the repeatability by a factor of 1.6. It is also found that adding a station at some locations will not improve the precision at all.

Evaluation of ICESat-2 ATL08 Data Product: Performance Assessment in Inland Water

Advanced Topographic Laser System (ATLAS) instrument on-board NASA's Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) enabled the capability of detecting certain properties of the Earth's surface at a photon level. Primary applications of ICESat-2 are for cryosphere but extendable to measure and determine the changes in elevation for land terrain and canopy. ICESat-2 ATL08 data product is a level 3A product that contains the best fit height above a reference ellipsoid processed in fixed 100 m data segments, which typically uses more than 100 signal photons from level 2 product namely ATL03. In this article, ICESat-2 ATL08 has been evaluated for its accuracy. Accuracy assessment of a point ellipsoidal height can be done using known benchmarks or survey points. In the absence of known points, the performance of these points can be assessed by hydro-flatness test as well as by comparing the satellite observed surface water level with gauged water table height. Both these tests have been done on 5 large reservoirs in the Indian sub-continent. Hydro-flatness test on ICESat-2’s ATL08 data product determined the permissible variations that occur on the surface water body due to ripples, wavelets, and streaks at a centimeter-level. Water level from ICESat-2 data will be in ellipsoidal height and cannot be compared with gauged data as it gives the height of the water surface above an established altitude where the stage is zero, because of this we have compared the change of surface water level from different dates. The results indicate that the surface water levels from ICESat-2’s ATL08 data product are in line with gauged data at centimeter-level accuracy.

Implementing Precision Approaches Supported by Satellite-Based Augmentation Systems in the Austrian Alps

Aerodromes located in mountainous areas are seldom served by approaches with three-dimensional guidance based on instrument landing systems due to the lack of flexibility to define glide paths free of obstacles. But, three-dimensional approaches are always preferred due to their effectiveness against controlled flight into terrain. Free access to three-dimensional angular approaches is possible today without special authorization and ground infrastructure. Some airports in mountainous areas of the United States, Canada, and Europe already benefit from them due to the latest advances in satellite-based augmentation techniques. The majority of these procedures have not been developed as category-one precision approaches, even though the latest operational service level foresees it. Reported here are the signal assessment and procedure design carried out to enable the first category-one precision approach supported by satellite-based augmentation system at an Austrian airport surrounded by one of the most challenging terrains worldwide. The design and implementation of such a procedure in mountainous terrain is feasible after a thorough signal quality assessment. It can be placed where a classical instrument landing-system-based approach procedure does not work and provides precision guidance for aircraft in instrument meteorological conditions. This in turn enables a higher runway throughput and reduces cost for the users. When the controlling obstacle is located outside of the precision segment, special attention should be put on the availability requirements.