The phenological dynamics of crops reflect the response and feedback of agricultural systems to climate and environmental constraints, and have significant controls on carbon and nutrient cycling across the globe. Remote monitoring of crop phenological dynamics in a consistent and systematic manner is vitally crucial for optimizing the farm management activities and evaluating the agricultural resilience

This study aims at investigating the fracture properties of double cantilever beam (DCB) by the combination of lightweight materials at opening and sliding modes. The specimens were prepared by referring to the British Standard of BS7991. In terms of experimental conditions, the lower part was fixed while the enforced displacement of 3 mm/min was applied to the upper part at both opening and sliding

The stability of the sandwich composite structures formed by leaving coal pillar, roof rock and floor rock (RCF) is of great significance to safe production of coal mines. The failure of coal and rock is actually a state instability phenomenon driven by energy. In order to explore energy characteristics of RCF sandwich composite structures, uniaxial compression tests with different coal thicknesses

In this work, formulas for the reflection and transmission coefficients of one-dimensional linear water waves propagating over a submerged structure with a cycloidal cross section in presence of a sloping beach are determined. In the specialized literature, the previous coefficients are obtained mainly for the limit of linear water waves, considering that the water depth upstream and downstream of

In this paper we proposed the kinetic framework based fifth-order adaptive finite difference WENO schemes abbreviated as WENO-AO-K schemes to solve the compressible Euler equations, which are quasi-linear hyperbolic equations that can admit discontinuous solutions like shock and contact waves. The formulation of the proposed schemes is based on kinetic theory where one can recover the Euler equations

Ge n+/p junctions fabricated by conventional ion implantation (CII) and plasma immersion ion implantation (PIII) are compared in this work. To achieve low junction leakage current, PIII-implanted Ge n+/p junctions require higher annealing temperature to eliminate the Shockley-Read-Hall generation current, which may be contributed to the residual hydrogen and hydrogen-related defects. It is demonstrated

In this paper, Fe3Al (Fe–23Al–3Cr) alloys reinforced with in-situ TiC precipitates were fabricated using a combination of high-energy ball milling and vacuum hot-pressing sintering technology. The experiment found that the 1 × 10−3 Pa vacuum was the optimal preparation conditions of composites. The results show that in-situ TiC ceramic is an efficient method to improve the mechanical properties of

Optimized tribological properties including low coefficient of friction (COF) and wear rate are significantly affected by main factors such as hardness, toughness and tribochemistry. In this research, a series of TiMoCN coatings with duty cycle from 20% to 80% were prepared by multi-arc-ion plating (MAIP). Mo and C addition prominently promote comprehensive tribological properties of TiN coatings by

Graphene oxide (GO) was introduced in this study as a hydrophilic enhancer to polyether block amide copolymer (PEBAX) in the form of thin film nanocomposite (TFNC) for hydrophobic based polysulfone (PSF) membrane. The objective is to increase hydrophilic moieties by providing more polar terminal within the TFNC network and by doing so, the film managed to completely reduce IPA traces in the permeate

P-type nitrogen-doped zinc oxide (NZO) thin film was prepared on a glass substrate by reactive magnetron sputtering using zinc metal target and O2/N2 atmosphere. The structural, electrical and optical properties of the NZO films were investigated by X-ray diffraction, electron microscopy, Hall-effect, and Raman scattering measurements. The electrical properties of the optimized p-type NZO films showed

In this article we present an investigation of three different fiber optic vacuum feedthroughs. Using Swagelok-type tube fittings, metal tubings containing the optical fibers are sealed into a vacuum flange. This allows for easy replacement of the feedthrough without replacing the entire flange. Employing only epoxy resin for sealing the optical fiber into the feedthough we have measured a helium diffusion

In the Water-Cooled Lithium Lead (WCLL) blanket, the eutectic alloy lithium-lead (PbLi) is used as tritium breeder and carrier, neutron multiplier and heat transfer medium. The liquid metal is distributed to and collected from the breeding zone through a compact poloidal manifold composed of two co-axial rectangular channels. The external channel, tasked with distribution, and the internal one, assigned

This letter develops a fog computing-based encrypted control system in a practical industrial setting. The developed system conceals controller gains and signals over communication links using multiplicative homomorphic encryption to prevent eavesdropping attacks. Experimental validation confirms the feasibility of position servo control for the motor-driven stage with the developed system in terms

A pose-graph-based optimization technique is widely used to estimate robot poses using various sensor measurements from devices such as laser scanners and cameras. The global navigation satellite system (GNSS) has recently been used to estimate the absolute 3D position of outdoor mobile robots. However, since the accuracy of GNSS single-point positioning is only a few meters, the GNSS is not used for

In this letter, we propose a framework that recognizes and describes changes that occur in a scene observed from multiple viewpoints in natural language text. The ability to recognize and describe changes that occurred in a 3D scene plays an essential role in a variety of human-robot interaction applications. However, most current 3D vision studies have focused on understanding the static 3D scene

Mobile robotics research and deployment is highly challenged by energy limitations, particularly in marine robotics applications. This challenge can be addressed by autonomous transfer and sharing of energy in addition to effective mission planning. Specifically, it is possible to overcome energy limitations in robotic missions using an optimization approach that can generate trajectories for both

Most of the current power line inspection robots use cameras and LiDARs to inspect the power line surfaces and the surrounding environment. But it is still difficult to detect the internal defects of the power lines. In this letter, the design and implementation of LineSpyX, a novel power line inspection robot based on digital radiography (DR), is introduced to solve the problem of non-destructive

To perch on or grasp the objective surface using the suction cup-based manipulator, the precise contact control is commonly required. Improper contact angle or insufficient contact force may cause failure. To enhance the tolerance to flight control insufficiency, a suction cup that comprises an inner soft cup and an outer firm cup to facilitate its engagement without reducing the adhesion stiffness

In this letter we address the mine countermeasures (MCM) search problem for an autonomous underwater vehicle (AUV) surveying the seabed using a side-looking sonar. We propose a coverage path planning method that adapts the AUV track spacing with the objective of collecting better data. We achieve this by shifting the coverage overlap at the tail of the sensor range where the lowest data quality is

Real world environments, such as kitchens, present objects covered in viscous fluids: soap, oil, water, etc. Understanding and designing for slippery and submerged contact, where fluid lubrication is present, is a continuing challenge in the robotics community. Contact area, bending stiffness, and the presence of a viscous fluid affect friction. This work focuses on milliscale features (3 to 20 mm

Accurate control of continuum robots requires handling non-linear behaviors between actuators and distal effectors. In this letter, we develop a method for estimating the non-linearities of tendon-driven degrees of freedom of flexible endoscopic systems by using a distal endoscopic camera and encoders at the proximal side. The proposed approach separates the non-linearities in two parts, namely a pure

This article proposes a learning method for denoising gyroscopes of Inertial Measurement Units (IMUs) using ground truth data, and estimating in real time the orientation (attitude) of a robot in dead reckoning. The obtained algorithm outperforms the state-of-the-art on the (unseen) test sequences. The obtained performances are achieved, thanks to a well-chosen model, a proper loss function for orientation

Modern robotic grippers are either specialized and simple, complex and general purpose, or soft and compliant hands. The first provide high reliability but are limited in the range of objects they grasp. Compliant or soft grippers can grasp wide ranges of objects, but are not yet reliable enough for real-world applications. This letter presents a novel variable-structure general purpose robotic hand

We discuss surveillance with multiple unmanned aerial vehicles (UAV) that minimize information idleness (the lag between the start of the mission and the moment when the data captured at a sensing location arrives at the base station) and constrain latency (the lag between capturing data at a sensing location and its arrival at the base station). This is important in surveillance scenarios where sensing

Many insects demonstrate remarkable locomotive capabilities on inclined or even inverted surfaces. Achieving inverted locomotion is a challenge for legged insect-scale robots because repeated attachment and detachment to a surface usually requires the design of special climbing gaits, adhesion mechanisms, sensing, and feedback control. In this study, we propose a novel adhesion method that leverages

Flexible pick-and-place is a fundamental yet challenging task within robotics, in particular due to the need of an object model for a simple target pose definition. In this work, the robot instead learns to pick-and-place objects using planar manipulation according to a single, demonstrated goal state. Our primary contribution lies within combining robot learning of primitives, commonly estimated by

With much research has been conducted into trajectory planning for quadrotors, planning with spatial and temporal optimal trajectories in real-time is still challenging. In this letter, we propose a framework for large-scale waypoint-based polynomial trajectory generation, with highlights on its superior computational efficiency and simultaneous spatial-temporal optimality. Exploiting the implicitly

To extend the mission duration of smaller unmanned aerial vehicles, this letter presents a solar recharge approach that uses lakes as landing, charging, and standby areas. The Sherbrooke University Water-Air VEhicle (SUWAVE) is a small aircraft capable of vertical takeoff and landing on water. A second-generation prototype has been developed with new capabilities: solar recharging, autonomous flight

We propose a soft robotic gripper that can handle various types of fabrics with delicacy for applications in the field of garment manufacturing. The design was inspired by the adhesion mechanism of a parasitic fish called ‘lamprey’. The proposed gripper not only is able to pick up and hold a single sheet of fabric from a stack but also does not make any damages on it. In this work, we first modeled

Untethered miniature robots have significant potential and promise in diverse minimally invasive medical applications inside the human body. For drug delivery and physical contraception applications inside tubular structures, it is desirable to have a miniature anchoring robot with self-locking mechanism at a target tubular region. Moreover, the behavior of this robot should be tracked and feedback-controlled

Sensing surroundings plays a crucial role in human spatial perception, as it extracts the spatial configuration of objects as well as the free space from the observations. To facilitate the robot perception with such a surrounding sensing capability, we introduce a novel visual task called Cross-view Semantic Segmentation as well as a framework named View Parsing Network (VPN) to address it. In the

This article presents a medical robotic system for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). ONSF is a currently invasive ophthalmic surgical approach that can reduce potentially blinding elevated hydrostatic intracranial pressure on the optic disc via an incision on the optic nerve. The prototype is a multi-arm system capable of dexterous manipulation and

We present a novel approach for traffic forecasting in urban traffic scenarios using a combination of spectral graph analysis and deep learning. We predict both the low-level information (future trajectories) as well as the high-level information (road-agent behavior) from the extracted trajectory of each road-agent. Our formulation represents the proximity between the road agents using a weighted

The use of untethered miniature swimmers is a promising trend, especially in biomedical applications. These swimmers are often operated remotely using a magnetic field commonly generated using fixed coils that can suffer from a lack of compactness and heating issues. The analysis of the swimming capabilities is still an ongoing topic of research. In this letter, we focus on the ability of a magnetic

The NA62 experiment is a fixed-target experiment at the CERN SPS. The main goal of the experiment is to measure the branching ratio of the ultra-rare kaon decay K + →π + ν ##IMG## [https://ej.iop.org/icons/Entities/barnu.gif] {bar nu} . The NA62 detector allows also to study other rare kaon decays and to search for very weakly coupled particles of MeV-GeV mass-scale. The new ANTI-0 hodoscope is proposed

In order to extend previous studies and test additional variables playing a role in the aging processes, a single wire proportional chamber was specially designed. In this contribution, the author will present the result of two types of tests performed on this single wire proportional chamber. During the first test, the single wire proportional chamber was irradiated with X-rays and alpha particles

Large water Cherenkov detectors have been successfully used for decades in high- and low-energy particle physics. Nevertheless, detecting neutrons remains a challenge for such detectors since a neutron capture on a hydrogen atom doesn't release a sufficient amount of gamma energy to be observed efficiently. The use of gadolinium in the form of soluble salts has been explored extensively to remedy this

The JOINBON Silicon Photomultiplier is a novel commercial silicon sensor for weak photon flux. In this paper we report a characterization of the sensor for the readout of LySO crystals with potential application to Positron Emission Tomography. We measured a energy resolution of approximately (13.50±0.03)% (FWHM) and a coincidence time resolution ranging between (215±3) ps for a 5 mm long crystal up

The measurements of the energy spread and the average beam energy for highly charged ion (HCI) beams, such as those delivered from EBIS charge breeder ion source and ECR ion source, demand the development of an energy analyzer of highest measurement efficiency. A new prototype of a compact analyzer called retarding field energy analyzer RFEA capable to handle all kinds of HCI beams at RISP project

A general-purpose SiPM electronics board has been developed in this work. Compared with commercial driver boards, this electronics board has a wider power supply range (20 V–90 V) to suit various types of SiPM. This new board enables cascading batch tests to meet the needs for high-volume SiPM testing procedures. More importantly, the new board can test SiPM timing performance down to a few tens of

Laser backscattering was implemented as a tool for accurate beam energy measurement at BES-III and VEPP-2000 electron-positron colliders. Here we summarize the experience obtained during these experiments. In fact, this report is the revised and updated version of our previous report on the same topic [1].

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Polypropylene (PP) is a widely used common type of polymer with excellent chemical and mechanical properties. Thermal aging is a main culprit in degrading its lifetime and effectiveness. In this article, terahertz (THz) dielectric frequency response of PP during the process of thermal aging is monitored and analyzed to understand the underlying mechanism and to qualify THz dielectric spectroscopy as

In this article, 150-GHz CMOS transmitter (TX) and receiver (RX) are presented for contactless and plastic waveguide communications. The implemented system employs a four-level pulse-amplitude modulation (PAM-4) and noncoherent detection. The direct upconversion TX and self-mixing RX suffer amplitude nonlinearity and distort the carrier-modulated multilevel signals. A current-mode digital predistortion

Microstructures of yttria-stabilized zirconia (YSZ) atmospheric-plasma-sprayed (APS) thermal barrier coatings (TBCs) and their terahertz dielectric properties were investigated to quantitatively determine porosities by effective medium theory (EMT). Various samples with different porosities ranged from 9.15% to 21.58% were prepared by different particle size powders and spray power. Both the theoretical

In this work, a new technique for the removal of water vapor absorption lines from terahertz signals based on deep neural networks is presented. The designed neural networks were trained on signals acquired under different air humidity, with and without samples. The neural networks were validated on signals of samples, which were not available to the neural networks during training. The quality of

The complete design process of a high-frequency circuit for a 263 GHz staggered double grating, sheet beam traveling wave tube is presented in this article. This device, for use in a pulsed electron paramagnetic resonance spectrometer instrument, requires >30 dB gain and a 20 GHz bandwidth centered at 263 GHz. In addition to the standard Pierce gain analysis and point by point particle in cell (PIC)

This letter proposes a 400-GHz leaky-wave antenna with low sidelobe level (SLL) and low cross-polarization level (CPL). Tapered radiation slots are designed for achieving a low SLL, virtual electrical walls are deployed to remove the loss from metal sidewalls by using a high-order mode feeding network, and a symmetrical layout with alternative-phase excitations is adopted for the array to suppress

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This paper presents passivity-based results to address stability of interfered digital filters with state-delay and saturation nonlinearities. A very-strict passivity condition is proposed for the digital filters by using an appropriate Lyapunov-Krasovskii functional. The established criterion ensures limit-cycle free realization of state-delayed interfered digital filters using saturation arithmetic

Variable impedance control improves compliance and robustness in robot-environment interaction through variation of the desired stiffness and the desired damping. This paper proposes neural approximation-based variable impedance controllers for robots in robot-environment interaction. Constraints on variable impedance parameters are given to ensure the exponential stability of the desired first- and

The combination of DC-DC buck power converters with DC motors for generating the so-called smooth start of drives has many advantages in engineering practice. Achieving high performance of such systems is, however, limited by the influence of disturbances/uncertainties of multiple sources. Some of the disturbances are mismatched, which makes them even more difficult to handle. Furthermore, the relatively

In this paper, we consider the control issues of the two-dimensional translational oscillator with rotational actuator (2DTORA) system, which has two translational carts and one rotational rotor. An output feedback controller for the 2DTORA system is proposed, which can prevent the unwinding behaviour. In addition, the velocity signal unavailability and actuator saturation are taken into account, simultaneously

This paper considers a consensus control of a general linear multi-agent system with time-varying communication delays. Since each agent can only use the relative output information from its neighbors, a reduced-order observer-based control protocol is proposed to guarantee consensus on the directed communication network. The stability of the closed-loop system is analyzed for the cases with uniform

This paper studies the fixed-time stability problem for positive nonlinear systems defined by cooperative vector fields. A criterion is derived to ensure fixed-time stabilization of the positive nonlinear systems using Lyapunov method. In addition, a sufficient condition is also presented for fixed-time stability of switched positive nonlinear systems under arbitrary switching. Simulation examples

This article investigates the distributed adaptive consensus tracking control problem for a class of high‐order nonlinear multiagent systems with unmodeled system dynamics, uncertain external disturbances, and event‐triggered communication. Under an undirected graph condition, a robust distributed adaptive consensus control scheme is proposed. To deal with the lumped system uncertainties involved in

This article proposes a Fuzzy Second Order Integral Terminal Sliding Mode (FSOITSM) control approach for DFIG‐based wind turbines subject to grid faults and parameter variations. Since traditional terminal sliding mode control (SMC) suffers from singularity, a novel integral terminal sliding manifold is proposed to eliminate chattering and improve the wind turbine's performance in the presence of faults