Flight Direction Research Articles

Where is the potential market for Taiwanese carriers to launch new direct flight services in Europe?

Taiwanese carriers face the difficulty in developing European direct flight market due to the air route limitation. Therefore, most passengers fly indirectly and mainly transit via other airports between Taiwan and Europe. In order to extend Taiwan - Europe flight market and improve Taiwan Taoyuan International Airport's (TPE) hub position, this study aims to indicate the potential European direct flight market by analyzing the passenger transfer dependency and further propose the flight frequency through the result of Cost-effectiveness analysis. One of the interesting results shows that passengers heavily rely on Dubai International Airport (DXB) and Hong Kong International Airport (HKG) for transferring between Taiwan and Europe. In addition, London Heathrow Airport (LHR) is the most profitable destination to launching new direct services. The results of this study provide the practical strategy to increase the connectivity of Taiwan-Europe flight market.

Experimental study of the features of post-stress recovery of psychophysiological functions using balneological treatments during the solstice

During the summer and winter solstices to study the features of post-stress recovery of psychophysiological functions of laboratory rats after light or dark deprivation, followed by physical exertion and rehabilitation procedures in the form of water and antler baths. The experiment was carried out on 160 male Wistar rats. The animals were divided into 8 groups of 10 individuals at each solstice period (winter, summer). Group 1 was not exposed to any impact. Group 2 was presented with physical activity (swimming test). These two groups were in natural light conditions. Groups 3-8 underwent light desynchronosis (light or dark deprivation) followed by physical activity. After the above-mentioned influences, procedures were carried out in the form of water baths (groups 4 and 7) and baths with a preparation based on pantogematogen «Pantovanna» (groups 5 and 8). Behavioral responses were assessed using the open field test. The content of corticosterone was determined by enzyme immunoassay. During the periods of the winter solstice, dark or light deprivation increased the resistance of animals to the stress of subsequent physical activity, i.e. showed a training effect, while during the summer solstice the studied stress factors led to depletion of serum corticosterone levels, although the structure of behavior did not undergo significant changes. Post-stress recovery in the form of water and antler baths for 10 days was determined by the nature of desynchronosis and the solstice period. Pantobaths were effective in summer and winter only under TT conditions. However, in winter, after the CC-regime, the antlers intensified the stressful effect of physical activity on the animals' organism. The experiment carried out indicates the need to take into account the season of the year and the direction of the transmeridian flight to balneological resorts. Using the example of solstices in experimental conditions on rats, we have shown that balneological procedures will perform best the restorative functions when expanding as a result of such a movement of the light phase of the day, but not the dark one. It is possible that this feature can also persist for a person, since a more rapid adaptation to new light-dark conditions has been established also with the expansion of the light phase, but not the dark one.

Speciality of restoring the psychophysiological parameters of laboratory rats with the help of balneological procedures during the periods of equinox

To perform a comparative study of balneotherapeutic procedures effectiveness in the form of water and antler baths in relation to the restoration of the psychophysiological parameters of laboratory rats after a consistent stressful effect of light desynchronosis and physical activity to a state of complete fatigue during autumn and spring equinoxes. The experiment was carried out during the periods of the spring and autumn equinoxes on 160 male Wistar rats weighing 220-250 g. In each season, the animals were divided into 8 groups of 10 individuals. Two groups were in natural lighting conditions. Animals of the 1st group (intact) were not exposed to experimental influences; rats of the 2nd group were exposed to physical activity in the form of a swimming test until complete fatigue for 5 days in a row in the morning; animals of groups 3-8 were exposed to stress loads in the form of 10-day light desynchronosis (light or dark deprivation) followed by physical activity. In the 4-th, 5-th, 7-th and 8-th groups, post-experimental post-stress recovery programs were carried out using water baths (groups 4 and 7) and baths with drug «Pantovanna» (groups 5 and 8). After the completion of exposures, the animals were tested in the «open field» according to the standard method. The level of corticosterone in the blood serum was determined by ELISA. It was found that in laboratory rats sensitivity to stressful influences - light desynchronosis followed by physical activity to the point of fatigue, as well as active post-stress recovery were determined by the nature of desynchronosis and the season of the year. The stress load was accompanied by a phase of exhaustion during the spring equinox and by a phase of anxiety during the autumn equinox. In the spring, antler baths as a procedure for active post-stress recovery were ineffective; in autumn, they had a normalizing effect on the level of corticosterone and behavior only after dark deprivation. The conducted experiment indicates the need to take into account the season of the year and the direction of the transmeridian flight to sanatorium-and-spa treatment with balneotherapy procedures. Using the example of equinoxes under experimental conditions on laboratory rats, it has been shown that balneological procedures will more effectively perform rehabilitative functions when the light phase of the day expands as a result of such a shift, but not the dark one.

On-Orbit Spatial Quality Evaluation of SDGSAT-1 Thermal Infrared Spectrometer

The Sustainable Development Science Satellite (SDGSAT-1) was successfully launched on 5th November 2021. It is the world’s first scientific satellite dedicated to serving the United Nations 2030 Agenda for Sustainable Development. To evaluate the on-orbit image quality of its thermal infrared spectrometer (TIS), we propose an improved edge slope calculation method. Learning from past academic research, we found that the traditional edge slop (ES) calculation methods are limited by various factors. For example, it demands highly on geographical aspects and surface temperature uniformity. In this paper, we interpolate the narrow sea-land boundary region. The edge signal-to-noise ratio and dip angle are calculated by the selected region to determine whether it satisfies the conditions of ES calculation. The Otsu algorithm is used to find the optimal threshold for the sea-land division, and the sub-pixel edge positions are extracted by combining with the canny operator. In order to achieve higher precision, we use the modified Fermi function to fit the extracted edge spread function (ESF). During the on-orbit testing of the SDGSAT-1/TIS, we performed ES calculations for a large number of test areas with a flight direction of 0.5 and a scan direction of 0.45.

Combined Attitude Determination for Real-Time Geomagnetic Navigation

In this letter, we present a novel algorithm to calculate attitude with data measured by a magnetometer and an accelerometer. The calculation error for the attitude angles is not affected by the external motion acceleration parallel to the plane, which is composed of the gravitational field and geomagnetic field. The simulation and actual experimental results have revealed that the algorithm improved the accuracy of the attitude estimated in roll or pitch angles for different flight directions compared with the arc-tangent attitude solution method. Our algorithm provides a new model for attitude estimation through a vector observation method and has excellent prospects in real-time, satellite-free geomagnetic navigation.

Hybrid SAR-ISAR Image Formation via Joint FrFT-WVD Processing for BFSAR Ship Target High-Resolution Imaging

Bistatic forward-looking synthetic aperture radar (BFSAR) is a kind of bistatic SAR system that can image forward-looking terrain in the flight direction of the receiver. Current literature and reports about BFSAR mainly concentrate on the stationary scene and ground-moving target imaging. Unlike stationary and ground-moving targets, the translational and rotational movements of ship targets usually lead to complicated range cell migration (RCM) and Doppler frequency migration (DFM). Moreover, the characteristics of RCM and DFM for different scattering points of the ship target are significantly different, i.e., the characteristics of the RCM and DFM are 2-D spatial variation, ultimately leading to severe defocusing of ship target in the SAR image. To solve these problems, a kind of hybrid SAR-ISAR imaging formation is proposed for BFSAR ship target imaging. First, to solve the problem of the Doppler ambiguity caused by the forward-looking mode of the receiver, an efficient ambiguity estimation method based on the minimum entropy criterion is presented. Then, keystone transform and range alignment processing can be applied to correct the spatial variant range walk and higher order RCM, respectively. Moreover, in order to obtain a high-resolution and well-focused image after translational compensation, a new method based on the fractional Fourier transform (FrFT) and the Wigner–Ville distribution (WVD) is proposed, where FrFT is applied to separate the multiple main scattering points in each range cell, and WVD is applied to obtain the high-resolution time–frequency distribution of each scattering point. Compared with the conventional ISAR range-Doppler (RD) algorithm and time–frequency estimation-based imaging methods, this method not only has no cross terms but also has high processing accuracy and better antinoise performance.

A Cyborg Insect Reveals a Function of a Muscle in Free Flight

While engineers put lots of effort, resources, and time in building insect scale micro aerial vehicles (MAVs) that fly like insects, insects themselves are the real masters of flight. What if we would use living insect as platform for MAV instead? Here, we reported a flight control via electrical stimulation of a flight muscle of an insect-computer hybrid robot, which is the interface of a mountable wireless backpack controller and a living beetle. The beetle uses indirect flight muscles to drive wing flapping and three major direct flight muscles (basalar, subalar, and third axilliary (3Ax) muscles) to control the kinematics of the wings for flight maneuver. While turning control was already achieved by stimulating basalar and 3Ax muscles, electrical stimulation of subalar muscles resulted in braking and elevation control in flight. We also demonstrated around 20 degrees of contralateral yaw and roll by stimulating individual subalar muscle. Stimulating both subalar muscles lead to an increase of 20 degrees in pitch and decelerate the flight by 1.5 m/s2 as well as an induce in elevation of 2 m/s2.

PROFESSIONAL RISKS WHEN APPLYING PESTICIDES USING UNMANNED AIRCRAFT: FEATURES AND COMPARATIVE HYGIENIC ASSESSMENT

Relevance. More and more widespread use in the world, and in Ukraine in particular, is acquiring a method of applying pesticides from the air using unmanned aerial vehicles (UAVs, or drones). It is expected that in the global agricultural market in the period from 2018 to 2026 the growth rate of drone use will be up to +18.5%.
 Objective: hygienic assessment of working conditions and occupational risks when applying pesticides using unmanned aerial vehicles (UAVs), analysis of their features and comparison with other most common types of treatment in agriculture.
 Materials and methods. Field studies were carried out in 2018–2021. When introducing the drug, certified equipment was used: a backpack sprayer SOLO-10, a trailed boom sprayer AMAZON 1201 UF combined with an MTZ 82.1 “Belorus” tractor, an Agras T16 unmanned aerial vehicle for spraying fields produced by DJ company, aircraft AN-2 combined with OZh-2 (with valveless liquid cut-off). Air sampling was performed using a “Typhoon” portable aspirator.
 Results. Analysis of calculations for the determination of inhalation for azoxystrobin (0.12 ± 0.004) and cyproconazole (54.2 ± 1.23); complex for azoxystrobin (0.52 ± 0.01) and cyproconazole (58.4 ± 1, 8) and combined (0.59 ± 0.01) risks showed that they are the highest for the signalman indicating the direction of flight to the pilot. Reliably lower risks of the negative impact of the working environment on the health of the sprayer tanker than the operator / tractor driver, aircraft pilot and signalman. Note that inhalation, percutaneous, complex and combined risks are reliably higher only for the drone tanker compared to the data for the outdoor pilot when a pesticide is introduced from the air.
 Conclusion. It was found that the risks for workers involved in the processing of crops by UAVs are significantly lower compared to aviation treatment, and are in the same range with the risks of other types of processing (rod, fan, knapsack).

Age-Related Changes of Gene Expression Profiles in Drosophila

An individual’s gene expression profile changes throughout their life. This change in gene expression is shaped by differences in physiological needs and functions between the younger and older organism. Despite intensive studies, the aging process is not fully understood, and several genes involved in this process may remain to be identified. Here we report a transcriptomic analysis of Drosophila melanogaster using microarrays. We compared the expression profiles of two-day-old female adult flies with those of 45-day-old flies. We identified 1184 genes with pronounced differences in expression level between young and old age groups. Most genes involved in muscle development/maintenance that display different levels of expression with age were downregulated in older flies. Many of these genes contributed to sarcomere formation and function. Several of these genes were functionally related to direct and indirect flight muscles; some of them were exclusively expressed in these muscles. Conversely, several genes involved in apoptosis processes were upregulated in aging flies. In addition, several genes involved in resistance to toxic chemicals were upregulated in aging flies, which is consistent with a global upregulation of the defense response system in aging flies. Finally, we randomly selected 12 genes among 232 genes with unknown function and generated transgenic flies expressing recombinant proteins fused with GFP protein to determine their subcellular expression. We also found that the knockdown of some of those 12 genes can affect the lifespan of flies.

The fastest routes of approach to dwarf planet Sedna for study its surface and composition at the close range

Current research focuses on designing fast trajectories to the trans-Neptunian object (TNO) (90377) Sedna to study the surface and composition from a close range. Studying Sedna from a close distance may provide unique data about the earliest stages of the Solar System evolution, including the protoplanetary disc stage and related mechanisms. The trajectories to Sedna are determined considering flight time and the total characteristic velocity (ΔV) constraints. The time of flight for the analysis was limited to 20 years. The direct flight, the use of gravity assist manoeuvres near Venus, the Earth and the giant planets Jupiter and Neptune, and the flight with the Oberth manoeuvre near the Sun are considered. It is demonstrated that the use of flight scheme with ΔVEGA (ΔV and Earth Gravity Assist manoeuvre) and Jupiter-Neptune gravity assist leads to the lowest cost of ΔV≈6.13 km/s for launch in 2041. The maximum payload for schemes with ΔVEGA manoeuvre is 500 kg using Soyuz 2.1.b, 2000 kg using Proton-M and Delta IV Heavy and exceeds 12,000 kg using SLS. For schemes with only Jupiter gravity assist, payload mass is twice less than for ones with ΔVEGA manoeuvre. As a possible expansion of the mission to Sedna, it is proposed to send a small spacecraft to another TNO during the primary flight to Sedna. Five TNOs suitable for this scenario are found, three extreme TNOs 2012 VP113, (541132) Leleākūhonua (former 2015 TG387), 2013 SY99) and two classical Kuiper Belts objects: (90482) Orcus, (20000) Varuna.

Adaptive Visual Servoing for Obstacle Avoidance of Micro Unmanned Aerial Vehicle with Optical Flow and Switched System Model

A vision-based adaptive switching controller that uses optical flow information to avoid obstacles for micro unmanned aerial vehicles (MUAV) is proposed in this paper. To use the optical flow to indicate the distance between the MUAV and the environment, we propose an algorithm with multi-thread processing such that the optical flow information is obtained reliably and continuously in the entire camera field of view. The flying behavior of considered MUAV is regarded as a switching system when considering different flying modes during the mission of obstacle avoidance. By the required flight direction for obstacle avoidance specified by the detected optical flow, an adaptive control scheme is designed to track the required trajectory in switching modes. The simulation result shows the tracking performances of the adaptive control with the switching system. The experiment of the whole system is completed to verify the obstacle avoidance capability of our system.

Measuring Beijing's international air connectivity and suggestions for improvement post COVID-19

This study empirically measures Beijing's international air connectivity through descriptive statistics and various connectivity indexes. In particular, we comprehensively benchmark Beijing's international air connectivity with other major international exchange centers and gateway airports around the world. It is found that, although Beijing has direct flights to a comparable number of foreign destinations, the city still significantly lags behind other major counterparts in international air connectivity. This is due to Beijing's inferior connection quality in terms of flight frequency, number of seats, flying distance, and its poor international transfer capability. Moreover, a gravity-type model is applied to investigate the determinants of Beijing's route-level direct flight traffic. An index of potential market size is calculated for a sample including candidate overseas airports without direct flights with Beijing. It is found that Beijing has already opened direct flights to most of the candidate airports that have high market potentials. The air transport market potentials to major B&R (Belt-and-Road) cities are very low. However, given China's growing trade and economic ties with the B&R countries, Beijing could consider more favorable policies in support of direct flight operations to B&R countries. It is more important for Beijing to upgrade air connectivity quality by liberalizing restrictions on flight frequency and airfare. The newly opened Beijing Daxing Airport adds valuable capacity for Beijing to better explore international connectivity. Although COVID-19 pandemic forces Beijing to shut down international flight operations until now, the city needs to formulate clearer long-term strategies to improve international its air connectivity.

Development of the Low Toxic Cross Polar Air Transport using Innovative Hydrogen Projection for Large Aircraft and Airships

The new shortly and low cost Regular Airlines Cargo & PAX directions via Arctic Cross Polar Air Transportation Routes of the future High Ecology Efficiency and Safety ICAO Strategy will be base on the more perspective for Trans Continental Airlines Operations by IATA International Law Regulations and World Climate Protect Law. Using the more shortly directions of Trans Polar Flight for Long-Haul Aircrafts (LHA) Routes by leader Airlines Sky Teams with Aeroflot are request to find new Geometrical Layout of Aircraft Design Industrial Projections & Products Lines. The increase in the dimension of LHA came into conflict with modern Airport Infrastructure and led to the search for alternative Arctic Planes & Dirigibles Options for constructively layout circuit solutions with protection of minimum weight and drag issues in order to deal with this contradiction. Computer Digital Aircraft Structural-Parametric Analysis of the influence of Aviation Infrastructure Constraints in the basing of LHA on the choice of alternative Design Options for Lift Fuselage Body or Flying-V layout was carried out.

Affordance-based control in deceptive and non-deceptive penalties in soccer goalkeeping: Gender matters!

Only few studies have addressed how soccer goalkeepers adapt to both the spatial and temporal constraints while trying to stop a penalty kick. Moreover, research on penalty kicks has only involved male goalkeepers, even though the resultant constraint (i.e., the relation between the maximum action capabilities defining the time required and ball flight time and direction defining the time available) may or may not differ for female goalkeepers. We therefore compared penalty goalkeeping between male and female goalkeepers of similar skill level. The results showed that the resultant constraint was more stringent for female than male goalkeepers. In accordance with the affordance-based control theory, female and male goalkeepers both adapted to the resultant constraint, but did scale their diving action differently. Female goalkeepers initiated the lateral dive within the action boundaries set by the resultant constraint, while male goalkeepers tended to dive late, beyond the action boundaries. Owing to the early dive, female goalkeepers saved more penalties than male in non-deceptive penalties. Nevertheless, female goalkeepers were also more susceptible to deception by the penalty taker than male goalkeepers. These findings extend our knowledge of the affordance-based control theory in sports and contribute to the understanding of gender differences in soccer penalty goalkeeping.

INSIGHTS ON THE ECONOMIC ESTIMATES OF THE CLIMATE COSTS OF THE AVIATION SECTOR DUE TO AIR MANAGEMENT IN 2018-19

Air navigation service providers ensure that aircrafts keep safely apart by prescribing vertical and horizontal distances to each other. In the European Union and its associated members, regulation is carried out via a performance scheme which measures and sets targets for the different key performance areas. For the environmental area, targets in terms of CO2 and other pollutants were set by assuming that there would be continuous improvements for the Key performance Environment indicator based on actual trajectory. However, although a higher Horizontal Flight Efficiency (HFE) measurement usually means a more direct flight trajectory, this does not necessarily translate into a climate optimal trajectory. Thus, vertical flight efficiency also needs to be considered. There is also an interdependency be¬tween airspace and Air Traffic Man¬agement Capacity and Environment: when the offered capacity falls short of the demand for flights, ground delays, holdings and traffic shifts to adjacent areas occur. This entails detours and a deterioration of the HFE-indicator. Results show that total climate costs for 2018 and 2019 may be as high as 1 bn EUR, of which about 34% is due to CO2 emissions. In particular, the climate costs of CO2 emissions due to capacity constraints range from 54 to 301 million EUR, depending on whether CO2 costs are measured in terms of avoidance costs or under the EU Emissions Trading System (EU ETS). Following the first criterion and the short to medium run up to 2030, the estimated costs would amount to 112 million EUR. In the long run, from 2040 to 2060, these costs would amount to 301 Million EUR. With the estimates of the EU ETS, the cost by 2030 would be close to 54 million EUR and 153.5 million EUR for the long run. Volatility of carbon pricing may play a very significant role, but fortunately can be hedged. Therefore, a shortfall of capacity leads to delay costs and considerable environmental costs. As capacity is planned in the medium to long-term, traffic forecasts are a crucial element. This means that further research is warranted into the interdependency of traffic forecasts, capacity and environmental costs. Keywords: climate economic cost, aviation sector, capacity management

Groping in the Fog: Soaring Migrants Exhibit Wider Scatter in Flight Directions and Respond Differently to Wind Under Low Visibility Conditions

Atmospheric conditions are known to affect flight propensity, behaviour during flight, and migration route in birds. Yet, the effects of fog have only rarely been studied although they could disrupt orientation and hamper flight. Fog could limit the visibility of migrating birds such that they might not be able to detect landmarks that guide them during their journey. Soaring migrants modulate their flight speed and direction in relation to the wind vector to optimise the cost of transport. Consequently, landmark-based orientation, as well as adjustments of flight speed and direction in relation to wind conditions, could be jeopardised when flying in fog. Using a radar system operated in a migration bottleneck (Strait of Messina, Italy), we studied the behaviour of soaring birds under variable wind and fog conditions over two consecutive springs (2016 and 2017), discovering that migrating birds exhibited a wider scatter of flight directions and responded differently to wind under fog conditions. Birds flying through fog deviated more from the mean migration direction and increased their speed with increasing crosswinds. In addition, airspeed and groundspeed increased in the direction of the crosswind, causing the individuals to drift laterally. Our findings represent the first quantitative empirical evidence of flight behaviour changes when birds migrate through fog and explain why low visibility conditions could risk their migration journey.

Camera traps with white flash are a minimally invasive method for long‐term bat monitoring

AbstractCamera traps are an increasingly popular survey tool for ecological research and biodiversity conservation, but studies investigating their impact on focal individuals have been limited to only a few mammal species. In this context, echolocating bats are particularly interesting as they rely less on vision for navigation, yet show a strong negative reaction to constant illumination. At hibernacula, camera traps with white flash could offer an efficient alternative method for monitoring threatened bat species, but the potential negative impact of white flash on bat behavior is unknown. Here, we investigate the effect of camera traps emitting white flash at four hibernation sites fitted with infrared light barriers, infrared video cameras, and acoustic recorders over 16 weeks. At each site, the flash was turned off every second week. We quantified whether flash affected (1) nightly bat passes using generalized linear mixed models, (2) flight direction of entering bats using permutational multivariate analyses, and (3) latency of the first echolocation call after the camera trap trigger using randomization tests. Additionally, we quantified and corrected for the potential impact of confounding factors, such as weather and social interactions. Overall, white flash did not influence short‐ or long‐term bat activity, flight direction or echolocation behavior. A decrease in nightly bat activity was observed with an increasing proportion of hours with rain. Moreover, flight direction was affected by the presence of other bats, likely due to chasing and avoidance behavior. Our findings highlight the potential of camera traps with white flash triggered by infrared light barriers as a minimally invasive method for long‐term bat population monitoring and observation of species‐specific phenology. Such automated monitoring technologies can improve our understanding of long‐term population dynamics across a wide range of spatial‐temporal scales and taxa and consequently, contribute to data‐driven wildlife conservation and management.

An analytical model to determine the impact force of drone strikes

In addition to the well-known threats of bird and hail strikes, small unmanned aerial vehicles (sUAV) pose a new threat to manned aviation. Determining the severity of collisions between sUAVs and aircraft structures is essential for the safe use and integration of drones in airspace. A generic analytical calculation model needs to be developed to supplement the existing test and simulation data. This paper presents an analytic model for drone collisions with perpendicular and inclined targets. The targets have a rigid or elastic material behavior. The aircraft impact model, which is used for the design of nuclear reactor structures, is transferred and adjusted for sUAV impacts to calculate the impact force. A mass- and a burst load distribution are needed as input parameters. Both distributions are determined for an sUAV design depending on the flight direction. Compared to previous calculations, the new approach is to consider a moving target structure, which produces more realistic results. We compare the calculation results with simulation data from sUAV collisions with a commercial airliner windshield from the literature. The calculations show plausible results and a good agreement with literature data. Subsequently, the influence of the input parameters on the impact force is investigated. We see that spring stiffness, target mass, burst load distribution and damping have minor influence on the overall impact force. The impact velocity, mass distribution and flight orientation on the other hand have a major influence on the impact force. Further tests are needed to validate the impact model.

Influence of habitat quality and resource density on breeding‐season female monarch butterfly Danaus plexippus movement and space use in north‐central USA agroecosystem landscapes

Abstract The eastern North American monarch butterfly is at risk of quasi‐extinction due, in part, to the loss of breeding habitat in agricultural landscapes of the USA Midwest. Because adult females are not patch residents, egg abundance and distribution across the landscape are a function of their perceptual range, flight directionality and flight step lengths. Conservation actions that account for habitat use in agricultural landscapes can enhance functional connectivity. Field‐captured females (n = 114) were released in a 64‐ha area containing restored prairies, grass‐dominated fields and crop fields in Floyd County, Iowa, USA, and two 1,000 m linear north–south sections of grass‐dominated roadside along secondary roads (~35 ha) with different proximity to prairie habitat in rural Story County, Iowa. Radio‐tagged or untagged monarchs were released in areas with high density, low density and zero density of forage and oviposition resources, as well as on habitat edges between high‐ and zero‐density habitats. Monarchs were observed for 1 hr. Radio‐tagged individuals that flew beyond visual detection were relocated using handheld radiotelemetry. Monarchs moved within and between habitat classes and typically performed upwind search behaviour. Monarchs successfully located resources, with some flying over 500 m to find high‐density areas, providing evidence that the monarch's perceptual distance is >100 m. Regardless of habitat class or field site, most step lengths were <50 m, and turn angles were directional. Large steps (≥50 m) crossing habitat boundaries occurred with approximately half of the monarchs, which may indicate initiation of long‐range searches for suitable habitat, consistent with their vagile behaviour. Establishing habitat patches 50 m apart in agricultural landscapes would facilitate efficient movement. Synthesis and applications. This study provides an extensive dataset of directly observed breeding‐season monarch butterflies to assess the utilization of agricultural landscapes. Documentation of step lengths >50 m in complex, agricultural landscapes would not have been possible without the aid of radiotelemetry. Results provide improved estimates of perceptual range and flight patterns within and between habitat patches that support models that simulate natural population dynamics to enable conservation planning at a landscape scale.

Three-dimensional and long-term landslide displacement estimation by fusing C- and L-band SAR observations: A case study in Gongjue County, Tibet, China

Recently, a large number of synthetic aperture radar (SAR) images has been introduced into landslide investigations with the growing launch of new SAR satellites, such as ALOS/PALSAR-2 and Sentinel-1. Therefore, it is appropriate to develop new approaches to retrieve three-dimensional (3D) displacements and long-term (> 10 years) displacement time series to investigate the spatio-temporal evolution and creep behavior of landslides. In this study, a new approach for the estimation of 3D and long-term displacement time series of landslides, based on the fusion of C- and L-band SAR observations, is presented. This method is applied to map 3D and long-term displacements (nearly 12 years) of the landslides in Gongjue County, Tibet in China; four sets of SAR images from different platforms (i.e., L-band ascending ALOS/PALSAR-1, C-band descending ENVISAT, and C-band ascending and descending Sentinel-1 SAR datasets) covering the period of January 2007 to November 2018 were collected and exploited. First, the assumption that the landslide moves parallel to its ground surface is used to produce 3D displacement rates and time series by fusing ascending and descending Sentinel-1 SAR images, from which the optimal sliding direction for each pixel of the slope is well estimated. Then, the long-term displacement time-series of the landslide between January 2007 and October 2018 in the estimated sliding direction is recovered by fusing L-band ALOS/PALSAR-1 and C-band Sentinel-1 SAR images. In order to fill the time gap of nearly four years between ALOS/PALSAR-1 and Sentinel-1 SAR images, the Tikhonov regularization (TR) method is developed to establish the observational equation. Moreover, to solve the problem arising from ALOS/PALSAR-1 and Sentinel-1 images with different wavelengths, incidence angles and flight directions, the measurements from ALOS/PALSAR-1 and Sentinel-1 images are both projected to the estimated optimal sliding direction to achieve a unified displacement datum. Our results from ascending and descending Sentinel-1 images suggest that the maximum displacement rates of the study area in the vertical and east-west directions from December 2016 to October 2018 were greater than 70 and 80 mm/year, respectively, and 2D displacement results reveal that the displacement patterns and movement characteristics of all the detected landslides are not identical in the study area. Specifically, the 3D displacement results successfully revealed the spatiotemporal displacement patterns and movement direction of each block of the Shadong landslide, and long-term displacement time series showed for the first time that the maximum cumulative displacement exceeds 1.3 m from January 2007 to October 2018. Moreover, the kinematic evolution and possible driving factors of landslides were investigated using 2D and 3D and long-term displacement results, coupled with hydrological factors and unidimensional constitutive models of the rocks.