Horizontal Area Research Articles

Optical coherence tomography angiography (OCT-A) in retinitis pigmentosa and macular dystrophy patients: a retrospective study

PurposeTo evaluate macular vascular abnormalities in patients with macular dystrophies (MD) and retinitis pigmentosa (RP) through application of optical coherence tomography angiography (OCT-A).MethodsIn this retrospective study, patients with MD and RP were examined by OCT-A and compared to healthy individuals. OCT-A images were analyzed regarding the diameter and surface area of the foveal avascular zone (FAZ) as well as flow (FL) in different retinal layers (superficial vascular complex (SVC), intermediate capillary complex (ICP), deep capillary complex (DCP), choriocapillaris (CC), and choroid (CD)).ResultsTwenty-one patients with MD, 21 patients with RP without macular edema (RPnE), 8 patients with RP with edema (RPwE), and 41 healthy individuals were enrolled. The group of MD and RPnE patients showed none or only minor changes in FAZ. In RPwE patients, the FAZ was significantly smaller in vertical and horizontal measurements and surface area in SVC, whereas it was markedly enlarged in ICP. FL was significantly reduced compared to healthy individuals by an average of 13.2% in CD, 14.2% in CC, and 8.4% in DCP in all patient groups. In ICP, the reduction was 9.2% for RPnE and 12.7% for RPwE patients. The SVC showed reduced FL in the MD (8.1%) and RPnE (10.3%) group.ConclusionsOCT-A is a valuable tool to examine retinal vascular abnormalities in patients with MD and RP. OCT-A revealed a reduced flow in various retinal layers in MD, RPnE, and RPwE. Alterations of the FAZ were less distinct in these groups which add to the variation reported previously.

Tracking the hydrologic response of agricultural tile outlet terraces to storm events

Agricultural practices in intensively managed landscapes are thought to be shifting hydro-bio-geochemical behavior from transformation to transport dominated systems. Here we explore the impacts of a best management practice known as tile-outlet-terraces (TOT). Tiles at this site are a set of perforated vertical pipes that can receive direct surface water, soil water and groundwater inputs that are connected to horizontal pipes that transport water to a receiving pond. Terraces are constructed, horizontal areas created to divide sloping terrains to reduce slope steepness and erosion, and in so doing they redirect surface water toward standpipes and promote soil and groundwater discharge as a result bisecting local flowpaths. While the impact of tiles on hydrologic behavior has been well studied, the combined impact of TOTs has not been well quantified. To address this knowledge gap, we focus on the response of TOT discharge and biogeochemical behavior across three adjacent agroecosystems in Kansas over three growing seasons (2016–2018). TOT discharge was measured every minute at each location and discharge during storm events was collected and analyzed for dissolved and total nutrients as well as major anion and cation chemistry. Additionally, suction cup lysimeters were installed at the ridges and depression of the terraces to capture soil water solute chemistry prior to storm events. Recession curve analysis revealed that tile inlet density was not directly related to the proportion of quickflow, mixing models showed that antecedent conditions played a critical role in the degree of connectivity of event water to the tiles, and concentration discharge behavior showed the dominant behavior for all constituents was chemostatic across all tile densities. Interestingly, these findings suggest that while TOTs shift the hydrology of agroecosystems away from natural conditions, the storm event size and antecedent conditions can still dominate the hydrologic and biogeochemical response to storm events.

Horizontal Charging Area Extension Based on Switchable Relay Coils

This article explores the potential of relay coils (ReXs) to extend the horizontal charging area for planar inductive couplers. It focuses on the coupling mechanism and derives the equivalent coupling coefficient for model simplification. Based on the new model, a one-ReX coupler is proposed to enhance the coupling under large misalignment. Besides, the influence of coupling polarity change is evaluated and well compensated. In order to further enhance the coupling, a multiple-ReX technique is proposed and justified by a two-ReX coupler and a three-ReX coupler. The experimental result shows that the enhanced coupling coefficient helps maintain the efficiency to be above 92.5% under large misalignment when the one-ReX coupler is used. With three ReXs, the achieved efficiency is further improved by 2.3%.

ГЕОМЕТРИЯ ЛОКАЛЬНЫХ КОНТУРОВ КАПЕЛЬНОГО УВЛАЖНЕНИЯ ПОЧВЫ, ФОРМИРУЮЩИХСЯ В ЮЖНЫХ ЧЕРНОЗЕМАХ

Purpose: to determine empirical dependencies that allow predicting the geometric parameters of local soil moisture contours formed during drip irrigation of southern chernozems. Materials and methods. The empirical basis of the study was the data of experimental measurements of the moisture contour parameters of southern chernozems, formed during drip irrigation, on 10 experimental sites, characterized by: the content of physical clay from 29.0 to 71.1 % of the dry soil mass (DSM), the field moisture capacity from 20.0 to 30.3 % of DSM, soil density from 1.29 to 1.4 t/cub. m. Soil characteristics were studied using the methods of N. A. Kachinsky, “flooded areas” and “cutting ring”. The moisture content of soil samples was determined according to GOST 28268-89. Results. Analytical processing of 10 experimental moisture contour outlines made it possible to obtain a system of empirical dependencies for determining the outline, diameter, horizontal projection area and volume of the local soil moisture contour. Dependencies take into account soil characteristics – the content of physical clay, the field moisture capacity and bulk density, as well as the technological parameters of drip irrigation – dripper consumption, moisture depth, levels of pre-irrigation and post-irrigation soil moisture and irrigation rate. The obtained dependencies were tested on the experimental data of other researchers. As a result, the deviations of the calculated values of the moisture contour diameter from the experimental ones did not exceed 11.3 % and averaged 4.8 %. Forecasting the area of the horizontal projection showed a deviation of the calculation from the experiment on average 8.9 %, and for the volume of the moisture contour – 8.8 %. Conclusions. Empirical dependences that allow predicting the shape, linear, areal and volumetric dimensions of soil moisture contours formed in southern chernozems during drip irrigation have been established. The results of testing help conclude that the proposed dependencies are acceptable for practical use.

Impact Analysis of Cluster Frontline Demonstrations on Groundnut in Nalgonda District, Telangana

The present study was conducted to analyze the yield gap between improved package of practices and farmers’ practice during rabi 2016-17 to 2020-21 in CFLDs on groundnut. The highest average pod yield was obtained in CFLDs (2341.6 kg/ha), with 27 per cent more against farmers’ practice (1843.6 kg/ha). The average extension gap, technology gap and technology index were 498.0 kg/ha, 658.4 kg/ha and 21.9 per cent, respectively. Sustainability yield index (0.78) and sustainability value index (0.84) averages were high in improved practice over the farmers’ practice (0.76 and 0.75). The average gross returns (Rs. 1,28,283.0/ha), net returns (Rs. 71,934.0/ha) and benefit-cost ratio (2.6) were higher in improved practice when compared to farmers’ practice. The mean of additional gross returns (Rs. 24,873.0/ha), cost of cultivation (Rs. 4,151.0/ha), net returns (Rs. 28,402.0/ ha) with incremental benefit-cost ratio of 6.0 was observed in improved practice. The average yield gap percentages within district and state averages were 64.2 per cent and 45.6 per cent, respectively. The per cent increased horizontal spread of area under groundnut was 14.1 per cent, 23.9 per cent and 27.5 per cent during study period, whereas in 2016-17 and 2018-19 per cent horizontal spread area decreased -52.3 per cent and -15.9 per cent, respectively with cultivation of improved varieties i.e., K-9 and ICGV 3043 against cultivation of old traditional varieties.

Определение количества капельных водовыпусков и их расположение в зоне питания плодовых культур

The purpose of study is to develop a method for determining the number of droppers required for drip irrigation of each tree in the garden and to evaluate their location patterns in the fruit crop feeding zone. The following criteria were adopted: the share of irrigated area from the feeding one should meet the needs of the cultivated crop, the number of droppers should be determined for each tree in the garden, the distance between the drip droppers and the tree trunk should be at least 0.2 m. As a result of the research, a multifactorial dependence was proposed to determine the required number of droppers, which takes into account the crop types, climatic conditions, crop planting pattern parameters, the required depth of soil moisture and the soil characteristics of the garden plot. Using the proposed method, the drip irrigation module parameters were calculated for three options of an apple garden planting 4.0 × 1.5 m, 4.0 × 2.0 m and 5.0 × 3.0 m on light, medium and heavy soils according to their mechanical composition. As a result of the calculation, it was found that in the considered combinations of soil conditions and crop planting patterns, from 2 to 12 droppers would be required for each tree. According to the results of the calculation, it can be stated that under the considered conditions, a single-line irrigation module cannot form a humidifi cation zone, which horizontal projection area corresponds to the needs of apple gardens. In eight of the nine combinations considered, the use of a double-line irrigation module is preferable. It should also be noted that on light soils, with the maximum of the considered feeding area (planting pattern 5.0 × 3.0 m), a two-line irrigation module cannot form a moistening zone with the required area in the soil space. In this case, it is necessary to use irrigation modules that provide for the use of special irrigation devices or the droppers location on branches from the main pipeline.

Evaluating Fire Risk of Long-term Care Hospitals for the Elderly

Long-term care hospitals for the elderly have a high risk of fire. To reduce this risk, the installation of a horizontal refuge area has been stipulated since 2015. However, most hospitals are still at risk due to the lack of retroactive regulations. Therefore, in this study, the efficiency of the horizontal refuge area was analyzed through evacuation safety evaluation using fire and evacuation simulations. As a result of evacuation safety evaluation for the two hospitals, the reduction ratio of evacuation time was 70% (day time) and 77% (night time). In addition, evacuation safety can be secured through the installation of a horizontal refuge area. The results of this study are expected to be used as a basis for preparing retroactive regulations for horizontal refuge areas in long-term care hospitals for the elderly in the future.

Multi-parameter aerodynamic design of a horizontal tail using an optimization approach

As one of the main components of conventional aircraft, the horizontal tail is of significant importance to safety; therefore, the horizontal tail is expected to achieve its goals in an optimum manner. The paramount importance of this study is addressing the designer's need to achieve harmonization between flight sciences such as aerodynamics, stability, and control, as well as manufacturing easiness, maintainability, and manufacturing cost throughout its service life. The main problem is defined as the minimum horizontal tail area that can meet the requirements of civil aviation regulations and other safety issues while improving cruise performance. Designing a horizontal tail with the smallest area has crucial advantages, such as lighter weight, lower drag, the forward-located center of gravity, lower slipstream effect when the propeller-on, longer cruise range, and lower manufacturing costs. This paper presents multi-parameter optimization of the horizontal tail using a multi-objective genetic algorithm, whereas the algorithm is fed by a stability derivative generator that is created using the artificial neural network trained with 225 different horizontal tail geometries' stability derivatives. The capabilities of the optimized geometry are examined by using a 6-degree-of-freedom mathematical model courtesy of the broad aerodynamic database of the base aircraft.

Disain Smart Electricity Penghematan pada Peralatan Listrik Menggunakan Sensor Ultrasonic

Waste of electricity is a problem that often occurs accidentally, especially in household electricity, especially on electrical equipment that is routinely used but forgets to turn it off if there are no users around electrical equipment such as fans, air conditioners, TVs and others. Saving electrical energy is an action to reduce the amount of electrical energy use. This study aims to create a control device for saving electricity consumption. Saving electricity consumption does not mean not using electrical energy for something that is not useful, however, energy savings can be achieved by using energy efficiently where the same benefits are obtained by using less energy. This study uses a design method or is designed to be smart electricity using sensors. ultrasonic with arduino uno, where this tool controls daily use in case of forgetting so that no energy is wasted (waste of electricity) or more practical in controlling electrical equipment. Based on the results of tool testing and data analysis carried out, it was concluded that the working system of this tool succeeded in controlling the use of electronic equipment by detecting the presence of an object / human with the help of an ultrasonic sensor with a horizontal area range. The Radio Frequency Identification sensor is an additional sensor to help the Ultrasonic sensor improve to detect in a wider range of vertical areas by scanning the card. The total cost of the entire expenditure for 1 month is Rp. 203,365 using a smart electricity design tool as a means of saving and the use of electricity based on ultrasonic sensors using Arduino Uno and Rp. 418,175 without tools results in a difference in savings of Rp. 214.810,-

Evaluation of effects of limited irrigation on regional-scale water movement and salt accumulation in arid agricultural areas

Irrigation plays an important role in agricultural production, especially in arid and semi-arid regions. However, the conflict between water supply and demand will become more serious with increasing population. This study was to evaluate the effects of limited irrigation on regional-scale water movement and salt accumulation processes in agricultural areas. Due to frequent vertical interactions between the saturated groundwater zone and the unsaturated soil water zone and significant lateral groundwater movement between different horizontal areas in arid and semi-arid agricultural areas with shallow groundwater level, a quasi-three-dimensional (quasi-3D) model was adopted, which coupled one-dimensional (1D) soil water and salt movement and 3D groundwater and salt movement. The Yonglian irrigation area was used as the typical study site. Nine limited irrigation scenarios based on different allocations of irrigation water and hydrological years were set and analyzed. The main results were as follows: (1) The net groundwater recharge is negative under most of limited irrigation conditions, causing the decline of groundwater level ranging from 0.028 m to 0.199 m within one year. (2) With the decrease of irrigation and precipitation in farmland during the crop growth period, the groundwater recharge, groundwater recharge concentration, leaching efficiency coefficient will decrease linearly, while soil salt storage index will increase linearly. (3) Salts may accumulate in the root zone for dry years or normal years with autumn irrigation water less than 100 mm per unit area. (4) Lateral groundwater fluxes and salts contained in lateral groundwater fluxes will reduce approximately 30% and 40% under limited irrigation conditions. (5) The root zone will suffer from a very severe threat of soil salinization in farmlands in the future when considering the average annual increase rate of soil salt in the root zone is 3.6% under limited irrigation conditions, and necessarily intervenes are needed. The results could support decision-making for water-saving and soil salinity prevention in arid agricultural districts.

Parameterised drag model for the underlying surface roughness of buildings in urban wind environment simulation

Knowledge of the flow field in the urban canopy layer (UCL) is of great significance in guiding the layout of buildings in blocks and mitigating local air pollution. Large eddy simulation (LES) with relatively high precision can simulate the flow field in the UCL. Considering the limitations of computational power, building resistance source parameterisation is an effective method of solving the average blocking effect of buildings on airflow and reducing the number of grids. Belcher's drag model has been widely used for calculating the average flow field in the UCL. However, the model does not consider the influence of the horizontal recirculation region and the variation of the canopy-drag length scale in the height direction. Therefore, a parameterised drag model for the resistance source of building(s) was improved by considering the horizontal recirculation region and effective roughness density. The simulation results suggest that the horizontal recirculation area of an isolated building is mainly affected by the spanwise width of the building at a certain height and presents a quadratic function distribution in the height direction, with a maximum at approximately z/H = 0.45. The validation of the isolated building and building arrays with different layouts demonstrated that the parameterised drag model could reveal the average flow field more accurately than Belcher's drag model.

Organic Field‐Effect Transistor Fabricated on Internal Shrinking Substrate

AbstractIn the development of flexible organic field‐effect transistors (OFET), downsizing and reduction of the operating voltage are essential for achieving a high current density with a low operating power. Although the bias voltage of the OFETs can be reduced by a high‐k dielectric, achieving a threshold voltage close to zero remains a challenge. Moreover, the scaling down of OFETs demands the use of photolithography, and may lead to compatibility issues in organic semiconductors. Herein, a new strategy based on the ductile properties of organic semiconductors is developed to control the threshold voltage at close to zero while concurrently downsizing the OFETs. The OFETs are fabricated on prestressed polystyrene shrink film substrates at room temperature, then thermal energy (160 °C) is used to release the strain. The OFETs conformally attached to the wrinkled structure are shown to locally amplify the electric field. After shrinking, the horizontal device area is reduced by 75%, and the threshold voltage is decreased from −1.44 to −0.18 V, with a subthreshold swing of 74 mV dec−1 and intrinsic gain of 4.151 × 104. These results reveal that the shrink film can be generally used as a substrate for downsizing OFETs and improving their performance.

Space use and activity of Boiga cyanea – A major songbird nest predator in a seasonal tropical forest in Thailand

Predator-prey interactions are fundamental drivers of population dynamics. Studying both predator and prey species simultaneously yields particularly useful insights into these complex interactions. Despite being significant, widespread avian nest predators, Southeast Asian snakes are rarely simultaneously studied in relation to avian prey. The Green Cat Snake Boiga cyanea is a primary nest predator, estimated to be responsible for 17–33% of forest songbird nest depredations in Northeast Thailand. We explored both diurnal and nocturnal movements of 14 (5 male, 9 female) adult B. cyanea with radio-telemetry for an average of 68 ± 16 days per individual, between 21 October 2017 and 8 June 2019 in the dry evergreen forest of the Sakaerat Biosphere Reserve (SBR). We quantified horizontal movements (m) and area of space use (ha) and activity through motion variance (Ϭ m 2 ) during the study period using dynamic Brownian Bridge Movement Models (dBBMMs) and reported our findings within the context of a simultaneously run avian nest monitoring study initiated in 2013 within the same forest. On average, adult B. cyanea moved 56.4 ± 10.4 m/day and used areas of 9.4 ± 3.4 ha, while their activity averaged 2.8 ± 0.8 Ϭ m 2 . Males moved 51.4 m/day farther than females, and in general, adult B. cyanea moved 50.3 m/day farther during the avian nesting season than the avian non-nesting season. We refrain from inferring statistical differences with the dBBMM outputs between sexes and seasons within our sample because of the unequal samples and sampling effort during the study period. Only two individuals (one male and one female) were sufficiently radio-tracked across both seasons (the avian nesting and non-nesting seasons), and these two displayed a clear increase in their respective movements, space use and activity during the avian nesting season. This could suggest that movements, space use and activity likely differ between the avian nesting and non-nesting seasons for male and female B. cyanea , however it is only two individuals. All individuals were exclusively nocturnal, moving throughout the night, and often descending from higher diurnal refugia (> 2 m) to forage closer to the ground after sunset. Our openly available data may yield further insight when combined with other major avian nest predator species like the congeneric invasive Brown Tree Snake Boiga irregularis on the island of Guam.

Spatial reconstruction of the sound field in a room in the modal frequency range using Bayesian inference.

Spatial characterization of the sound field in a room is a challenging task, as it usually requires a large number of measurement points. This paper presents a probabilistic approach for sound field reconstruction in the modal frequency range for small and medium-sized rooms based on Bayesian inference. A plane wave expansion model is used to decompose the sound field in the examined domain. The posterior distribution for the amplitude of each plane wave is inferred based on a uniform prior distribution with limits based on the maximum sound pressure observed in the measurements. Two different application cases are studied, namely a numerically computed sound field in a non-rectangular two-dimensional (2D) domain and a measured sound field in a horizontal evaluation area of a lightly damped room. The proposed reconstruction method provides an accurate reconstruction for both examined cases. Further, the results of Bayesian inference are compared to the reconstruction with a deterministic compressive sensing framework. The most significant advantage of the Bayesian method over deterministic reconstruction approaches is that it provides a probability distribution of the sound pressure at every reconstruction point, and thus, allows quantifying the uncertainty of the recovered sound field.

Effects of building setback on thermal comfort and air quality in the street canyon

The concern of mitigating thermal stress and pollutant concentration has increased in recent urban design. Most previous studies have demonstrated the promising potential of integrating building setbacks to simultaneously improve thermal comfort and air quality within street canyons. By conducting computational fluid dynamic (CFD) simulations with the consideration of solar radiation, the effects of both horizontal and vertical building setbacks on outdoor thermal comfort and air quality are simultaneously investigated inside the low-rise and high-rise street canyon. Several design parameters of building setbacks are considered, i.e., the dimensionless height (HHS/W) and dimensionless width (DHS/W) for the horizontal setbacks (HS), as well as the dimensionless length (LVS/L) and dimensionless width (DVS/W) for the vertical setbacks (VS), where W and L are the street width and length. The results demonstrate that the horizontal building setbacks are advocated within the low-rise street canyon, which simultaneously improves the thermal comfort and air quality. By manipulating its dimensionless vertical cross-section area SHS (increasing SHS = HHS/W × DHS/W) and its dimensionless aspect ratio HHS/DHS (lowering HHS/DHS), the average PET can decline by up to 2.1 °C and the average pollutant concentration can reduce by up to 61% at the two-side pedestrian level (windward and leeward sides). The vertical building setbacks are more suitable for the high-rise street canyon to create better outdoor environments. The dimensionless horizontal cross-section area SVS (= LVS/L × DVS/W) should be as large as possible so that the average PET can decrease by up to 0.7 °C and the average pollutant concentration can reduce by up to 35% at the two-side pedestrian level. Finally, an effectiveness index to simultaneously evaluate thermal comfort and air quality is introduced and proves effective.

Aircraft Configuration Parameter Boundaries Based on Closed-Loop Flying Qualities Requirements

For aircraft employing the fly-by-wire technique, the closed-loop dynamic characteristics are determined by both the configuration design and the flight control system. As the capacity of the control system has certain limitations, the configuration parameters are also constrained by the requirements of the closed-loop flying qualities. This paper presents an aircraft configuration parameter boundaries determination method based on closed-loop flying qualities requirements independent of the actual flight control law design, mainly aiming at the parameters that affect the stability and control characteristics. First, a nonlinear dynamic inversion-based flight control law is adopted to decouple the control law gains from the configuration parameters and to study the relationship between the configuration parameters and closed-loop flying qualities. Second, a flying qualities evaluation scheme is established by selecting the most severe flight conditions and the evaluation criteria that are most sensitive to changes in the parameters. Finally, the parameter boundaries according to the requirements of Level 1 flying qualities are determined by searching for the critical values that lead to degradation of the flying qualities. The proposed method is verified by an application example of the design ranges of a sample aircraft’s wing position, horizontal tail area, center of gravity, vertical tail area and vertical tail position.

Using fractal dimension to correct clumping effect in leaf area index measurement by digital cover photography

The leaf area index (LAI), defined as one-half of the total green leaf area per unit horizontal ground surface area, is a key parameter in agriculture, forestry, ecology, and other fields. The clumping index (CI) accounts for the nonrandom spatial distribution of the foliage elements in the canopy, thereby considerably influencing the accuracy of LAI estimation with optical field-based instruments. Most of the traditional clumping effect correction methods for LAI measurements are based on the theory developed for one-dimensional (1D) data of the vegetation canopy. The development of new methods remains necessary for LAI measurement with two-dimensional (2D) data, including images from digital cover photography (DCP). We found that the fractal dimension (FD) of a 2D ground-based DCP image is an effective tool for correcting the clumping effect and estimating the LAI. The universal formula was derived to describe the relationship between the LAI and FD for randomly distributed leaves using the box-counting method (BCM) and the Boolean model. For the clumped leaves, the universal formula is related to the FD, LAI, and CI. The LAI and CI can be calculated with the FD and gap probability derived from DCP images. Eighteen simulated scenes of different vegetation structure patterns, three realistic canopy scenes of the fourth phase of the radiative transfer model intercomparison (RAMI), and field-measured data acquired from 5 plots in 4 temporal phases were provided to validate the method. The results showed good agreement with the reference (R2 = 0.93 and RMSE = 0.46 for simulated data; uncertainty from 0.31 to 1.05 for realistic canopy; R2 = 0.85 and RMSE = 0.34 for field-measured data). This validation with downward DCP images shows that the proposed FD method assesses the clumping effect more thoroughly compared to the clumping effect correction methods originally designed for 1D data. The FD method is expected to improve the measurement accuracy of LAI with DCP images, especially for heterogeneous canopies.

Geologic Controls on Erosion Mechanism on the Alaska Beaufort Coast

Two prominent arctic coastal erosion mechanisms affect the coastal bluffs along the North Slope of Alaska. These include the niche erosion/block collapse mechanism and the bluff face thaw/slump mechanism. The niche erosion/block collapse erosion mechanism is dominant where there are few coarse sediments in the coastal bluffs, the elevation of the beach below the bluff is low, and there is frequent contact between the sea and the base of the bluff. In contrast, the bluff face thaw/slump mechanism is dominant where significant amounts of coarse sediment are present, the elevation of the beach is high, and contact between the sea and the bluff is infrequent. We show that a single geologic parameter, coarse sediment areal density, is predictive of the dominant erosion mechanism and is somewhat predictive of coastal erosion rates. The coarse sediment areal density is the dry mass (g) of coarse sediment (sand and gravel) per horizontal area (cm2) in the coastal bluff. It accounts for bluff height and the density of coarse material in the bluff. When the areal density exceeds 120 g cm−2, the bluff face thaw/slump mechanism is dominant. When the areal density is below 80 g cm−2, niche erosion/block collapse is dominant. Coarse sediment areal density also controls the coastal erosion rate to some extent. For the sites studied and using erosion rates for the 1980–2000 period, when the sediment areal density exceeds 120 g cm−2, the average erosion rate is low or 0.34 ± 0.92 m/yr. For sediment areal density values less than 80 g cm−2, the average erosion rate is higher or 2.1 ± 1.5 m/yr.

An experimental study on the motion of solid spheres under solitary wave attack

In the present study, the motion of a single and the motion and collision of two spheres on a horizontal area under solitary wave attack are investigated, constituting a unique and integrated dataset. Sixteen experimental cases are considered on four experimental configurations changing the number of spheres, the porosity of the bottom, water levels, and the breaking condition of the solitary waves (non-breaking or breaking). The motion of the spheres is tracked using a color-detection-based image-processing algorithm. The experiments reveal four significant results: (i) The rate of damping on the porous bottom is 1.65 times of impermeable bottom on average. (ii) The water level changes the characteristics of the motion of the spheres significantly due to the friction forces and vortex structures created by the interaction of waves with moving spheres. (iii) The dimensionless terminal velocities of the spheres in the non-breaking cases are 1.38 times of breaking solitary wave cases on average. (iv) The type of solitary wave and the water level significantly affect the collision behavior; however, the bottom condition does not have an apparent contribution to the collision behavior.

The EU’s cybersecurity: a strategic narrative of a cyber power or a confusing policy for a local common market?

In the last decade, cybersecurity has swiftly turned into a strategic issue and became an important horizontal policy area in the EU, which is treated in this article as one of the four contemporary political empires. These days, the policy arguably encompasses both internal and external aspects, often making it difficult to assess the level of its actual effectiveness as well as outreach. Initially, the EU’s introverted vision on the issue drove the policy to focus on cyber resilience and strategic autonomy. Evidently, the EU’s strategic narrative that could assist it in leading the process of creating an open, free, stable and secure cyberspace in the digital decade, in the context of international security, is emerging. Thus, this contribution is to test the argument that the EU, utilizing an imperial paradigm (consciously or not), is gradually becoming a global steering power in cybersecurity. In this article, firstly, we identify and examine the process of formation of the EU’s narratives about (its) cyber power. Secondly, we establish a discussion framework to highlight the methodological relevance of the imperial paradigm, cyber power Europe and Strategic Narrative Theory for a multidisciplinary debate on global geo-strategic redesign, in which the EU takes part. Thirdly, we look into bilateral and multilateral forums and processes that deal with cybersecurity and in which the EU participates, in order to understand more specifically how the EU is projecting its cyber-power narratives internationally and how cybersecurity-associated challenges impact current dynamics in other policy domains in the field of international relations.
 Recibido: 20 noviembre 2020Aceptado: 18 mayo 2021