Efficient Mode Research Articles

Design and Implementation of a Multimodal Tilt‐Rotor Unmanned Aerial‐Aquatic Vehicle

ABSTRACTThe unmanned aerial‐aquatic vehicle (UAAV) can be operated in both air and water for scientific and engineering applications. However, the endurance and maneuverability of the UAAV are challenged by the complex multi‐domain tasks. Inspired by the locomotion modes of the tilt‐rotor unmanned aerial vehicle (UAV) and the hybrid underwater glider (HUG), the design and implementation of a multimodal tilt‐rotor UAAV are presented in this paper. This UAAV can repeat trans‐domain and move in both air and underwater. To minimize configuration redundancy and weight of the vehicle, the amphibious structures are implemented, which include a waterproof air tilt‐rotor to provide vector pull for underwater propulsion, a movable buoyant tailplane to adjust the pitch angle for underwater gliding, a distributed variable buoyancy system (DVBS) to control buoyancy, and the hollow wings with a 10° dihedral angle to assist water exit. The vehicle prototype was fabricated, and tested in ocean environments, lakes, and high‐visibility pools. The results demonstrate that the vehicle can perform controllably and repeatedly trans‐domain under disturbed conditions, and the combination of efficient and flexible locomotion modes can enhance the endurance and maneuverability of the vehicle in multidomain environments. In particular, the underwater endurance of over 12 h, and the underwater attitude response rates improve by over 100%. Moreover, the vehicle's weight is decreased by over 39% owing to the implementation of amphibious structures.

Electrical shock injuries: an analysis of voltage, frequency, and contact mode determinants

This article examines the precision of medical terminology commonly used to diagnose and understand the pathogenesis of electrical shock injuries. As everyday technology increasingly depends on advanced electrical mechanisms that utilize more efficient modes of electrical energy transmission, waveforms, and frequencies, emergency and trauma physicians will continue to encounter a broader array of electrical injury manifestations. This phenomenon prompts a closer examination of the diagnostic terminology associated with electrical shocks. The pathogenesis of electrical injury depends on the tissue electric field strength, frequency, current duration, and tissues involved. Some traditional diagnostic terms, for example, “entry” and “exit” wounds, arc-flash burns, and “high-voltage” and “low-voltage” electrical injuries, obscure the complexity of this pathogenesis, likely impeding medical management and advances in electrical safety science. This article presents the scientific rationale for suggested changes to medical terminology and aims to encourage future refinement.

Computational model of a feeding copepod engaged in three modes of movement

Abstract Objectives: Copepods display distinct feeding modes to capture prey in the surrounding water. However, the mechanism and range of prey detection are not fully understood. Methods: Using the method of regularized Stokeslets, we constructed a mathematical model of the flow field around a copepod engaged in three modes of movement: sinking, swimming and hovering. The model assumes that the copepod is negatively buoyant with a simplified body and a pair of long antennae. We then introduced a rigid, neutrally buoyant sphere in the model to predict where potential prey items become detectable in theory. Key Findings: We find that the flow fields around the sinking and swimming models are generally unidirectional, while the flow around a hovering copepod has a significant cross-stream component. Our model shows that the volume of the surrounding fluid that is predicted to be inspected has distinctive shapes that resemble a thin sheet while sinking, a cylinder while swimming and a funnel while hovering. Conclusion: The results suggest that the most efficient mode of feeding depends on the distribution of prey items in the surrounding water.

Efficient TE-polarized mode coupling between a plasmonic tunnel junction and a photonic waveguide

Efficient TE-polarized mode coupling between a plasmonic tunnel junction and a photonic waveguide

Vehicle-To-Grid (V2G) Charging and Discharging Strategies of an Integrated Supply–Demand Mechanism and User Behavior: A Recurrent Proximal Policy Optimization Approach

With the increasing global demand for renewable energy and heightened environmental awareness, electric vehicles (EVs) are rapidly becoming a popular clean and efficient mode of transportation. However, the widespread adoption of EVs has presented several challenges, such as the lagging development of charging infrastructure, the impact on the power grid, and the dynamic changes in user charging behavior. To address these issues, this paper first proposes a vehicle-to-grid (V2G) optimization framework that responds to regional dynamic pricing. It also considers power balancing in charging and discharging stations when a large number of EVs are involved in scheduling, with the aim of maximizing the benefits for EV owners. Next, by leveraging the interaction between environmental states and the dynamic behavior of EVs, we design an optimization algorithm that combines the recurrent proximal policy optimization (RPPO) algorithm and long short-term memory (LSTM) networks. This approach enhances system convergence and improves grid stability while maximizing benefits for EV owners. Finally, a simulation platform is used to validate the practical application of the RPPO algorithm in optimizing V2G and grid-to-vehicle (G2V) charging strategies, providing significant theoretical foundations and technical support for the development of smart grids and sustainable transportation systems.

Factors influencing the digital intelligence transformation of offshore wind power enterprise

China's offshore wind power industry is advancing toward a digital transformation, and its development is considered a crucial strategic pillar of China's energy structure transformation. Facing challenges such as high costs, technical difficulties, lack of industry standards, insufficient industrial economies of scale, and even ecological threats, China's offshore wind power industry in the new period urgently requires innovative paths for further development. Driven by policy guidance and market demand, many enterprises have embarked on digital upgrading by introducing digital technology into their business processes, thus achieving a more efficient and intelligent production management mode to enhance industry competitiveness. However, due to the inherent peculiarities of the offshore wind power industry, its implementation of digital technology faces certain technical difficulties and systemic risks. This study presents a case study of Mingyang Smart Energy and related organizations conducted using in-depth interviews, and focuses on the practical circumstances of China's offshore wind power industry undergoing digital transformation. This study also applies the grounded theory to analyze the driving factors and mechanisms of digital transformation and provides an in-depth discussion of the characteristics of different stages of the transformation, including digital technology function leap, management and platform construction, as well as digital operation and value creation. The study results can enrich the theoretical study of digital transformation and provide practical guidance for the offshore wind power industry to achieve intelligent, efficient, and sustainable development.

Novel intercellular spread mode of respiratory syncytial virus contributes to neutralization escape

Developing widely used respiratory syncytial virus (RSV) vaccines remains a significant challenge, despite the recent authorization of two pre-F vaccines for elderly adults. Previous reports have suggested that even when vaccine-induced immunity generates high titers of potent neutralizing antibodies targeting the pre-F protein, it may not fully inhibit breakthrough of RSV infections. This incomplete inhibition of RSV breakthrough infections can lead to an increased risk of enhanced respiratory disease (ERD) in vaccinated individuals. The reasons why potent neutralizing antibodies cannot fully prevent RSV breakthrough infections are not yet clear. In an attempt to explain this phenomenon, we investigated the effect of potent neutralizing antibodies on the intercellular spread of RSV. Our findings indicated that a specific titer of potent neutralizing antibodies, such as 5C4, could block certain modes of intercellular spread, such as the diffusion of cell-free virions and the delivery of virions through filopodia. However, these antibodies did not fully inhibit the entire process of intercellular spread. Through the use of super-resolution imaging techniques, we observed a novel and efficient spread mode called the transition of viral materials through intercellular nanotubes (TVMIN), independent of virions and insensitive to the presence of antibodies. TVMIN allowed RSV-infected cells to directly transfer viral materials to neighboring cells via intercellular nanotubes that are rich in microfilaments. TVMIN began as early as 5 h post-infection (h.p.i.) and rapidly initiated infection in recipient cells. Our data provided new insights into the intercellular spread of RSV and might help explain the occurrence of breakthrough infections.

Streamlined line-defect taper design for broadband and efficient mode coupling: connecting a silicon strip with a planar valley photonic crystal zigzag interface.

The integration of planar valley photonic crystal (VPC) interfaces into high-speed data communication chips markedly improves data rates and system robustness. This Letter presents a novel, to the best of our knowledge, edge coupler, termed the line-defect taper, which is crucial for efficient and broadband light delivery to planar VPC interfaces via silicon strip waveguides. The coupling performance of the line-defect taper is evaluated through full-wave three-dimensional finite-element simulations. The results demonstrate a -3 dB transmission bandwidth of 65.5 nm, covering 41.2% of the topological bandgap, and a -1 dB transmission bandwidth of 16.3 nm, accounting for 10.3%. With its compact design (only 3.6 µm in length), simplicity, and scalability, the line-defect taper is a promising candidate for integration into densely packed chips, highlighting its potential in advancing on-chip devices.

Analysis of Changes in the Stress–Strain State and Permeability of a Terrigenous Reservoir Based on a Numerical Model of the Near-Well Zone with Casing and Perforation Channels

A finite element model, which includes reservoir rock, cement stone, casing, and perforation channels, was developed. The purpose of the study is to create a geomechanical model of the zone around the well, which includes support elements and perforation channels. This model will help predict changes in the productivity coefficient of a terrigenous reservoir and determine the most efficient mode of operation of a producing well. In order to exclude the stress concentration within the casing–cement stone and cement stone–rock, the numerical model applies contact elements. As a result, structural elements slip, while the stresses are redistributed accurately. The numerical simulation of a stress state in the near-well zone was carried out by using the developed model with differential pressure drawdown on the terrigenous reservoir, one of the oil fields in the Perm region. It is shown that the safety factor of the casing reaches roughly 3–4 units. The only exceptions are the upper and lower parts of the perforations, where this parameter is close to one unit. The safety factor of cement stone accounts for 2–3 units. However, parts with its lowest value (1.35) are also concentrated near the perforation channels. In order to analyze the change in permeability, the dependence of the safety factor on effective stresses was taken into account. Therefore, it was found that, in the upper and lower parts of perforations, the stresses decreased, while permeability rose by up to 20% of the initial value. An increase in differential pressure drawdown, on the contrary, can lead to a permeability reduction of 25%, especially in the lateral parts of the perforations. Areas of rock destruction under tensile and compressive forces were identified by using the Mohr–Coulomb criterion. It is estimated that with an increase in pressure drawdown, the areas of rock destruction under tensile force disappear, while the areas of rock destruction under compression increase. After further analysis, it was found that, with the maximum pressure drawdown of 12 MPa, the well productivity index can decrease by 15% due to the reservoir rock compaction.

Lossy Mode Resonance Optical Fiber Enhanced by Electrochemical-Molecularly Imprinted Polymers for Glucose Detection.

Noninvasive glucose sensors are emergent intelligent sensors for analyzing glucose concentration in body fluids within invasion-free conditions. Conventional glucose sensors are often limited by a number of issues such as invasive and real-time detection, creating challenges in continuously characterizing biomarkers or subtle binding dynamics. In this study, we introduce an efficient lossy mode resonance (LMR) optical fiber sensor incorporating the molecularly imprinted polymers (MIPs) to amplify glucose molecules. A molecularly imprinted recognition platform is created on an LMR sensor surface through a convenient one-step electrochemical (EC) polymerization method, in which 3-Aminophenylboric acid and glucose serve as the functional monomer and template molecule, respectively. LMR resonance wavelength shift induced by the coupling of the optical lossy mode and the fiber core mode is employed as the parameter to characterize biomolecules. Due to its high sensitivity to surrounding environment changes, a limit of detection (LOD) of 4.62 × 10-2 μmol/L for glucose can be achieved by this optical fiber sensor. Additionally, the prepared EC-MIPs LMR sensor is capable of detecting glucose molecules in human saliva samples with high accuracy, endowing its potential for practical applications.

Witnessing an extreme, highly efficient galaxy formation mode with resolved Lyman-α and Lyman-continuum emission

J1316+2614 at z = 3.613 is the UV-brightest (MUV = −24.7) and strongest Lyman continuum-emitting (fescLyC ≈ 90%) star-forming galaxy known; it also shows signatures of inflowing gas from its blue-dominated Lyα profile. We present high-resolution imaging with the Hubble Space Telescope (HST) and the Very Large Telescope (VLT) of the LyC, Lyα, rest-UV, and optical emission of J1316+2614. Detailed analysis of the LyC and UV light distributions reveals compact yet resolved profiles, with LyC and UV morphologies showing identical half-light radii of reff ≃ 220 pc. The continuum-subtracted Lyα emission, obtained with the HST ramp-filter FR551N, reveals an extended filamentary structure of ≃6.0 kpc oriented south to north with only residual flux within the stellar core, suggesting a Lyα ‘hole’. Our spectral energy distribution analysis shows that J1316+2614 is characterised by a young (5.7 ± 1.0 Myr), nearly un-obscured stellar population with a high star-formation rate (SFR = 898 ± 181 M⊙ yr−1) and a stellar mass of M⋆young = (4.8 ± 0.3) × 109 M⊙. Additionally, the spectral energy distribution analysis supports the absence of an underlying old stellar population (M⋆old ≤ 2.8 × 109 M⊙, 3σ). J1316+2614 presents remarkably high SFR and stellar mass surface densities of log(Σ SFR[M⊙ yr−1 kpc−2]) = 3.47 ± 0.11 and log(ΣM⋆[M⊙pc−2]) = 4.20 ± 0.06, respectively, which are among the highest observed in star-forming galaxies and are more typically observed in local young massive star clusters and globular clusters. Our findings indicate that J1316+2614 is a powerful, young, and compact starburst that is leaking a significant amount of LyC photons due to a lack of gas and dust within the starburst. We explored the conditions for gas expulsion using a simple energetic balance and find that, given the strong binding force in J1316+2614, a high star-formation efficiency (ϵSF ≥ 0.7) is necessary to explain the removal of gas and its exposed nature. Our results thus suggest a close link between high ϵSF and high fescLyC. This high efficiency can also naturally explain the remarkably high SFR, UV luminosity, and efficient mass growth of J1316+2614, which acquired at least 62% of its mass in the last 6 Myr. J1316+2614 may exemplify an intense, feedback-free starburst with a high ϵSF, similar to those proposed for UV-bright galaxies at high redshifts.

Theoretical investigation on crash performance of bamboo-inspired energy absorption systems based on systematic experimental and numerical analysis

The need for energy-absorbing devices with adaptable crashworthiness is increasingly urgent in various engineering fields with diverse load environments. For this aim, bamboo-inspired modular energy absorption systems have recently been proposed to integrate mechanical efficiency, tunability, and robustness. However, their mechanical responses under varying load velocities have not been systematically studied, which limits the effective prediction and optimization of their crashworthiness. In this study, quasi-static and dynamic experiments were performed on bamboo-inspired systems, discretely assembled using 3D printed steel tube specimens. Matched finite element simulations were conducted using ABAQUS/Explicit. Specific energy absorption and efficiency of these systems respectively exceeded 12.9 J/g and 47 %, surpassing existing discretely assembled systems and rivaling typical cellular materials. Efficient deformation mode with self-locking capability was observed, and sharp impact peak was avoided when the crash velocity was less than 50 m/s. Building upon these findings, a modified spherical shell theory under crashing was developed to predict energy absorption performance of bamboo-inspired system based on the traveling plastic hinge model. The average relative error between the analytical solution and finite element results was found less than 6.5 %. The mean effective stress of the system could exceed 35 MPa under thickness-to-diameter ratio of 5 %. This work presents an efficient and effective approach for optimizing and estimating the crash performance of modular protective devices.

Demand rerouting mechanisms with revenue management for intermodal barge transportation networks

Inland waterway transportation plays a crucial role in Europe's transportation network and economy. It is an efficient and sustainable mode of transportation, with lower emissions and energy consumption than other modes of transportation, such as road and air. However, the services provided by inland waterway transport can be significantly impacted by adverse weather conditions such as heavy rain, strong winds, and flooding. These disruptions can cause delays, cancellations, or even damage to vessels or infrastructure. To improve the system reliability, we propose a set of revenue management based (demand itinerary) rerouting mechanisms for intermodal barge transportation optimisation. Revenue Management policies including several customer categories and fare differentiation are applied. Sequential accept/reject decisions are made based on a probabilistic mixed integer programming model maximising the expected revenue of a carrier. A booking framework is defined over a rolling horizon and capacity allocation/reallocation decisions are made for a set of demands including the current and relevant past and potential future transportation requests. Several (demand) rerouting mechanisms are defined and implemented on different service network configurations. The service network status is regularly updated, in particular with respect to barge capacity variations due to changing water levels. An extensive set of experiments is performed and numerical results are analysed. The study results emphasise the added value but also the need for data availability and information sharing between the different stakeholders of Inland Waterway Transportation systems.

Counterintuitive Yet Efficient Regimes for Measurement-Based Quantum Computation on Symmetry-Protected Spin Chains.

Quantum states picked from nontrivial symmetry-protected topological (SPT) phases have computational power in measurement-based quantum computation. This power is uniform across SPT phases, and is unlocked by measurements that break the symmetry. Except at special points in the phase, all computational schemes known to date place these symmetry-breaking measurements far apart, to avoid the correlations introduced by spurious, nonuniversal entanglement. In this work, we investigate the opposite regime of computation where the symmetry-breaking measurements are packed densely. We show that not only does the computation still function, but in fact, under reasonable physical assumptions, this is the most resource efficient mode.

A multi-bionic design strategy for modular energy absorption system based on interlocking suture integrated with Bouligand-like arranged perforations

Thin-walled tubes are widely used in the field of cushioning energy absorption as an ideal structural unit. However, the performance of the thin-walled tube system is greatly limited by the presence of redundant connection structures. To address these issues, a multi-bionic design strategy for high-performance modular system was developed in this work, which innovatively combines the robust joint structure of the interlocking suture with the efficient deformation mode of the Bouligand structures. In the design process, the suture-inspired system was studied separately, and its mechanical behaviors were investigated by FEM simulations and experiments. The results showed that the modular system has good structural scalability and tunable deformation mode, and can be adjusted on demand to accommodate different loads and geometric features. Furthermore, in order to reduce the weight and improve the deformation degree of the system, an optimization strategy inspired by the efficient deformation mode of the Bouligand structure was proposed by perforating a sequence of helix-arranged guide holes in the sidewalls of the tubes. The results showed that the double-helix perforated system can reduce the weight by 10% while increasing the specific energy absorption by 58% compared with the unperforated system. In addition, the specific energy absorption and energy absorption efficiency of the system are as high as 48.25 J/g and 56.17%, which is comparable to traditional honeycomb sandwich panels while retaining structural stability and adjustable performance. Therefore, this multi-bionic strategy can integrate the advantages of various natural structures and provide new insights for the design of high-performance protective systems.

Failure mechanism and crashworthiness optimization of variable stiffness nested origami crash box

In recent years, the study of the crashworthiness of lightweight and efficient thin-walled energy-absorbing structures has received increasing attention. In this work, 3D printing technology was adopted to create a nested origami crash box with stiffness variation, which was made of short carbon fiber reinforced nylon material. The structure effectively inhibits the development of failure behavior of short carbon fiber-reinforced nylon origami crash box due to material brittleness. The quasi-static compression experiment results indicate that compared to origami crash box, nested origami crash box improves by 40% in specific energy absorption and 50% in crash force efficiency, while the initial peak crushing force remains unchanged. The effects of three key geometrical parameters, namely dihedral angle, distance between tubes, and height difference on the damage mechanism of the nested origami crash box are discussed in detail using the finite element method, and the response surface model combined with the non-dominated sorting genetic algorithm II is used for multi-objective optimization. In this work, the concepts of origami theory and nested systems are integrated for the first time, aiming to achieve a stable and efficient energy-absorbing deformation mode by precisely modulating the stress transfer path of the structure and its stiffness. This work provides new ideas for the design and fabrication of novel lightweight energy-absorption boxes.

An Approach for Estimating the Contributions of Various Real-World Usage Conditions towards the Attained Utility Factor of Plug-in Hybrid Electric Vehicles

Plug-in hybrid electric vehicles (PHEVs) are designed to enable the electrification of a large portion of the distance vehicles travel while utilizing relatively small batteries via taking advantage of the fact that long-distance travel days tend to be infrequent for many vehicle owners. PHEVs also relieve range anxiety through seamless switching to hybrid driving—an efficient mode of fuel-powered operation—whenever the battery reaches a low state of charge. Stemming from the perception that PHEVs are a well-rounded solution to reducing greenhouse gas (GHG) emissions, various metrics exist to infer the effectiveness of GHG reduction, with utility factor (UF) being prominent among such metrics. Recently, articles in the literature have called into question whether the theoretical values of UF agree with the real-world performance of PHEVs, while also suggesting that infrequent charging was the likely cause for observed deviations. However, it is understood that other reasons could also be responsible for UF mismatch. This work proposes an approach that combines theoretical modeling of UF under progressively relaxed assumptions (including the statistical distribution of daily traveled distance, charging behavior, and attainable electric range), along with vehicle data logs, to quantitatively infer the contributions of various real-world factors towards the observed mismatch between theoretical and real-world UF. A demonstration of the proposed approach using data from three real-world vehicles shows that all contributing factors could be significant. Although the presented results (via the small sample of vehicles) are not representative of the population, the proposed approach can be scaled to larger datasets.

Design of a switchable triple-waveguide-based TE-converted polarization beam splitter based on lithium niobate

The lithium-niobate-on-insulator (LNOI) platform has been the new force to drive the developments of integrated photonics, where efficient polarization management and mode conversion are the fundamental issues to be solved. In this work, we proposed a switchable TE-converted polarization beam splitter (PBS) based on optical phase change material (PCM) and a triple-waveguide in simulation. To optimize and analyze the proposed design, the 3D finite difference time domain (3D-FDTD) method is applied in this work. The simulated results indicate that when PCM is in the amorphous state, the device can effectively separate the TM and TE modes, achieving a low insertion loss (<0.5dB) for both modes at 1550 nm. While the PCM is in the crystalline state, the proposed device can realize the efficient conversion from the input TE0 mode to output TE1 mode, which obtains a mode conversion efficiency of 99.5%, crosstalk of −26dB, and insertion loss of 0.5 dB at 1550 nm. We hope such a device can make compact integration and capacity improvement for the integrated photonics in LNOI.

Analytical Overview of the Methods of Controlling the Parameters of Vibratory Compaction of the Concrete Mixes

Introduction. A historical (retrospective) overview of the evolution and application of the methods of concrete mixture compaction by vibration, as well as an overview of the breakthrough scientific+ advancements in the studied field have been presented. The use of the dry concrete mixes that reduce cement consumption, accelerate the strength gain of concrete, reduce the shrinkage strain and heat emission and increase the strength and durability of products has been proposed. The theoretical and practical issues of vibratory compaction of the concrete mixes, the research on the effect reached by the various vibration modes of the vibrating tables, the issues of choosing an efficient mode of vibration impact during compacting the concrete mixes and optimisation of their parameters have been studied. The vibrating table design, the installation layout of the vibrator’s eccentric weights to obtain a given value of the exciting force and the layout of a vibration module with the directed vibrations have been studied in detail. The criteria of duration of the concrete mixture compaction have been defined, changes of the impact parameters during compacting the concrete mixes have been characterised and technical specifications of the vibrating tables have been defined. In the article considerable attention has been paid to the main parameters of the vibrocompacting machines: frequency, amplitude and acceleration of the working member. Most often, the parameter of intensity is used to assess the efficiency of the vibration impact received by the mixture during the compaction process.Materials and Methods. A mixture that turns into concrete after compaction, setting and hardening was selected for the research. The various methods and parameters of concrete mixture compaction to obtain the high-quality concrete were studied. The impact of the various vibration modes on the process of compaction of concrete mixes was investigated, the criteria for the efficient selection and optimisation of the vibration impact parameters were revealed. The paper presents the criteria for assessing duration of the concrete mixture compaction and describes the changes in the parameters during compaction of the concrete mixes. The technical specifications of the vibrating tables of different types and sizes were also presented. The choice of the vibration compaction mode for the concrete mixture is a complicated task, which includes many parameters.Results. Upon the research, the data on the process of concrete mixture compaction under the impact of vibration forces has been obtained. The process results in the destruction of the structural bonds and weakening the bonds between the particles, which leads to the emergence of a variable stress-strain condition. It has also been found that under such settings, the mineral particles get transferred and a denser packing is formed.Discussion and Conclusion. The resulting denser packing of the concrete mixture particles ensures the undoubted economic advantage due to reduced consumption of a binder without loss of the strength properties of concrete.

Non-Hermitian mode management in periodically modulated waveguide amplifiers

We propose an efficient mode management scheme in active nonlinear multimode fibers based on non-Hermitian potentials in the longitudinal direction with an antisymmetric transverse profile. The proposal takes advantage of the nonlinear saturation toward particular mode configurations, which can be tuned by the non-Hermitian potential. We demonstrate flexible control of the beam profile within the parameter space of the applied potential with various possibilities, such as improving the beam quality by condensing photons to the lowest order Hermite mode, exciting higher order modes, or engineering a desired mode profile as a combination of modes. The effect is also analytically predicted using a mode-expansion approach, showing good agreement with the full model calculations based on the complex Ginzburg–Landau equation. This study was performed for 1D planar guiding structures, yet the results can be extended to 2D fibers and could be very useful in applications of fiber amplifiers and lasers.