Adaptive Devices Research Articles

(Invited) Optical Properties and Active Plasmon Excitations in 2D Materials

The control and tuning of the optical properties of materials and the localization of electromagnetic energy are long standing quests for scientists. Not only it allows to design new classes of adaptive devices such as smart windows but also to perform surface enhanced vibrational spectroscopies such a SERS.For metallic nanostructured systems, the optical properties are directly related to collective electronic excitation (plasmons) and they depend mainly on the composition, shape and size of the system. Doped semiconductors such as Indium Tin Oxide have been also shown to display active plasmon, i.e., optical excitations that can be easily controlled by an external stimulus, e.g. a static electric potential [1].In 2D materials, an electrostatic doping is common due to the low density of state at the Fermi energy. Moreover, anisotropy plays a very specific role [2] and surface plasmon became 1D plasmon. In this presentation, based on numerical simulations, we analyze the plasmon excitation associated to edge of 2D materials or to metallic mirror twin boundaries in Transition Metal Dichalcogenide [3]. Doped graphene [4] nanodots or shape engineering in wrinkled structures will also be discussed.[1] A. Maho et al. Solar Energy Materials and Solar Cells 200 (2019) 110014[2] B. Majerus et al. Phys. Rev. B 98 (2018) 125419[3] A. A. Koos et al. J. Phys. Chem 123 (2019) 24855[4] F. Joucken et al. Phys. Rev. Mat. 3 (2019) 110301

An angle-changeable tracked robot with human-robot interaction in unstructured environments

PurposeThe purpose of this paper is to study the adaptability of the tracked robot in complex working environment. It proposes an angle-changeable tracked robot with human–robot interaction in unstructured environment. The study aims to present the mechanical structure and human–robot interaction control system of the tracked robot and analyze the static stability of the robot working in three terrains, i.e. rugged terrain, sloped terrain and stairs.Design/methodology/approachThe paper presents the mechanical structure and human–robot interaction control system of the tracked robot. To prevent the detachment of the tracks during obstacle navigation, a new type of passively adaptive device based on the relationship between the track’s variable angle and the forces is presented. Then three types of rough terrain are chosen to analyze the static stability of the tracked robot, i.e. rugged terrain, sloped terrain and stairs.FindingsThis paper provides the design method of the tracked robot. Owing to its appropriate dimensions, good mass distribution and limited velocity, the tracked robot remains stable on the complex terrains. The experimental results verify the effectiveness of the design method.Originality/valueThe theoretical analysis of this paper provides basic reference for the structural design of tracked robots.

Investigating the formation and consolidation of incidentally learned trust.

People make inferences about the trustworthiness of others based on their observed gaze behavior. Faces that consistently look toward a target location are rated as more trustworthy than those that look away from the target. Representations of trust are important for future interactions; yet little is known about how they are consolidated in long-term memory. Sleep facilitates memory consolidation for incidentally learned information and may therefore support the retention of trust representations. We investigated the consolidation of trust inferences across periods of sleep or wakefulness. In addition, we employed a memory cueing procedure (targeted memory reactivation [TMR]) in a bid to strengthen certain trust memories over others. We observed no difference in the retention of trust inferences following delays of sleep or wakefulness, and there was no effect of TMR in either condition. Interestingly, trust inferences remained stable 1 week after learning, irrespective of the initial postlearning delay. A second experiment showed that this implicit learning occurs despite participants’ being unable to explicitly recall the gaze behavior of specific faces immediately after encoding. Together, these results suggest that gist-like, social inferences are formed at the time of learning without retaining the original episodic memory and thus do not benefit from offline consolidation through replay. We discuss our findings in the context of a novel framework whereby trust judgments reflect an efficient, powerful, and adaptable storage device for social information.

Experimental and computational analysis of thermal environment in the operation of HfO2 memristors

Neuromorphic computation using nanoscale adaptive oxide devices or memristors is a very promising alternative to the conventional digital computing framework. Oxides of transition metals, such as hafnium (HfOx), have been proven to be excellent candidate materials for these devices, because they show non-volatile memory and analog switching characteristics. This work presents a comprehensive study of the transport phenomena in HfOx based memristors and involves the development of a fully coupled electrothermal and mass transport model that is validated with electrical and thermal metrology experiments. The fundamental transport mechanisms in HfOx devices were analyzed together with the local and temporal variation of voltage, current, and temperature. The effect of thermal conductivity of substrate materials on the filament temperature, voltage ramp rate, and set/reset characteristics was investigated. These analyses provide insight into the switching mechanisms of these oxides and allow for the prediction of the effect of device architecture on switching behavior.

Asymmetric voltage multiplying circuit coupled to sliding electrodes for biomass fractionation with high-voltage and high current pulsed electric fields

Pulsed electric field (PEF) is an emerging technology for biomass processing and fractionation by electroporation of cell membrane. Nevertheless, PEF technology and devices require tailoring and adaptation for each specific type of biomass. Such an optimization requires convenient and adaptable laboratory systems, which will enable both electrical and mechanical parameters determination before process upscaling. In this work, we report on the design and development of a laboratory PEF system that allows applying for up to 4[Formula: see text]kV, 1[Formula: see text]kA pulses with 1–100[Formula: see text][Formula: see text]s and total power dissipation of 20[Formula: see text]W and up to 25[Formula: see text]kg of mechanical load. The design of an asymmetric voltage multiplying circuit allows for controlling pulse parameters for each pulse in series. Such an approach enables precise adaptation of PEF to the changing conductivity of the biomass, minimizing the total invested energy in the process. The system was tested on highly conductive marine macroalgae Ulva sp, a promising but challenging feedstock for the biorefinery. This work provides a design of an adaptable PEF device, important for biomass processing with electroporation.

Adaptive Safety Early Warning Device for Non-contact Measurement of HVDC Electric Field

In order to prevent electric shock accidents during the maintenance and repair of high-voltage direct current (DC) live equipment, an intelligent safety early warning system device based on non-contact electric field measurement is developed in this paper, to ensure the life safety of electrical workers and the stable operation of equipment. Firstly, the self-developed electric field sensor is used to measure the electric field strength of the space around the charged device. The STM32 microprocessor in the sensor will compare the measured electric field value with a preset safety threshold. If the safety threshold is exceeded, the early warning device issues an audible alarm. It prompts the electric power operator to exit to a safe distance. In addition, the alarm prompt symbol and the real-time waveform of the measured electric field can be seen intuitively on the mobile smart APP interface. Secondly, for devices with different voltage levels, the sensor electric field measurement range and sensitivity can be dynamically adjusted by changing the motor speed. In addition, according to the voltage level identification algorithm, this is also to achieve an adaptive safety early warning of different live equipment. Finally, field experiments were performed at a ±500 kV DC converter station and an ±800 kV DC transmission line experimental platform. The measured values of the electric field are basically consistent with the simulated values, and the safety early warning device has no false positives or false negatives during the test. The experimental results show that the design of the safety warning device in this paper meets the actual needs, and it can alert the electric workers to the specified safety distance.

Impact of the thermal environment on the analog temporal response of HfOx-based neuromorphic devices

Filamentary adaptive oxide devices based on HfOx are a promising technology for neuromorphic computing applications. The resistance of these devices depends on the concentration of oxygen vacancies in the filament region. A local temperature rise from joule heating plays a significant role in the movement of oxygen ions, making thermal management crucial to reliable performance. In this work, the role of the substrate thermal conductivity on the analog performance was investigated at biologically realistic pulse widths. Au/Ti/HfOx/Au adaptive oxide devices were fabricated on substrates with two orders of magnitude difference in thermal conductivity. A lower thermal conductivity substrate dissipates heat more slowly, resulting in a large initial change in resistance from a single operation pulse, which is detrimental to the desired analog behavior. The results were validated by a COMSOL Multiphysics® model that models the flow of heat in both samples.

Impact of Substrate Rigidity on the Structure of Multilayer Nanoscale ITO Films: Implications for Flexible Electronic Devices

Polymeric substrates have become increasingly important in the recent drive in technology to produce flexible displays and mechanically adaptable devices. Multi-nanoscale layer coatings are often n...

Adaptive Water Sampling Device for Aerial Robots

Water quality monitoring and predicting the changes in water characteristics require the collection of water samples in a timely manner. Water sample collection based on in situ measurable water quality indicators can increase the efficiency and precision of data collection while reducing the cost of laboratory analyses. The objective of this research was to develop an adaptive water sampling device for an aerial robot and demonstrate the accuracy of its functions in laboratory and field conditions. The prototype device consisted of a sensor node with dissolved oxygen, pH, electrical conductivity, temperature, turbidity, and depth sensors, a microcontroller, and a sampler with three cartridges. Activation of water capturing cartridges was based on in situ measurements from the sensor node. The activation mechanism of the prototype device was tested with standard solutions in the laboratory and with autonomous water sampling flights over the 11-ha section of a lake. A total of seven sampling locations were selected based on a grid system. Each cartridge collected 130 mL of water samples at a 3.5 m depth. Mean water quality parameters were measured as 8.47 mg/L of dissolved oxygen, pH of 5.34, 7 µS/cm of electrical conductivity, temperature of 18 °C, and 37 Formazin Nephelometric Unit (FNU) of turbidity. The dissolved oxygen was within allowable limits that were pre-set in the self-activation computer program while the pH, electrical conductivity, and temperature were outside of allowable limits that were specified by Environmental Protection Agency (EPA). Therefore, the activation mechanism of the device was triggered and water samples were collected from all the sampling locations successfully. The adaptive water sampling with Unmanned Aerial Vehicle-assisted water sampling device was proved to be a successful method for water quality evaluation.

Stabilization of Port Hamiltonian Chaotic Systems with Hidden Attractors by Adaptive Terminal Sliding Mode Control.

In this study, the design of an adaptive terminal sliding mode controller for the stabilization of port Hamiltonian chaotic systems with hidden attractors is proposed. This study begins with the design methodology of a chaotic oscillator with a hidden attractor implementing the topological framework for its respective design. With this technique it is possible to design a 2-D chaotic oscillator, which is then converted into port-Hamiltonia to track and analyze these models for the stabilization of the hidden chaotic attractors created by this analysis. Adaptive terminal sliding mode controllers (ATSMC) are built when a Hamiltonian system has a chaotic behavior and a hidden attractor is detected. A Lyapunov approach is used to formulate the adaptive device controller by creating a control law and the adaptive law, which are used online to make the system states stable while at the same time suppressing its chaotic behavior. The empirical tests obtaining the discussion and conclusions of this thesis should verify the theoretical findings.

Programmable passive actuation for adaptive building façade design using hygroscopic properties of wood

ABSTRACT This paper exploits the hygroscopic properties of wood and its passive response to fluctuation of relative humidity to develop a framework for programmable actuation in adaptive building façade design. This responsive shape shifting mechanism is specifically employed for the embedded actuation of dynamic shading configurations. Utilizing the hygroscopic properties of wood in adaptive shading devices embraces passive motion with a low-cost and low-tech approach, as a response to rapid climatic changes. Using physical experiments and image analysis, changes in the deflection and angle of curvature of wood samples in response to fluctuation in relative humidity were measured and tracked. A set of controlled hygroscopic parameters affecting the motion response of wood were deduced, including the fixation position, fixation type, and percentage and location of isolated areas of wood samples, thus achieving more control of response behavior and multiple shading percentages. A parametric script was developed using Grasshopper graphical algorithm editor and Ladybug environmental plugin to simulate shading configurations for the identified control parameters in the summer and winter solstices for an adaptive façade prototype.

‘Rehabilitation aids for the blind’: disability and technological knowledge in Canada, 1947-1985

ABSTRACT Contrary to stereotypes that portray people with disabilities as passive recipients of technological innovation, individuals with sensory and mobility impairments have played key roles in the invention, design and use of adaptive or assistive devices over the course of the twentieth century. This article interrogates this history through a case study focusing on the research program of James Swail, an engineer with the National Research Council (NRC) of Canada from 1947 until 1985. As someone who was himself blind, Swail’s predicated his design work on an asset-based understanding of disability. He strived to disrupt conceptions of both the technological functionality and economic rationality of technologies produced for and by disabled people in mid-twentieth century Canada. Framed within a medical model, however, the overall fate of these machines mirrored back the imagined inability of people with disabilities to become fully participating members of the society in which they lived.

АДАПТИВНОЕ УСТРОЙСТВО ПРЕДЫСКАЖАЮЩЕЙ ЛИНЕАРИЗАЦИИ ДЛЯ БОРТОВЫХ РАДИОПЕРЕДАЮЩИХ УСТРОЙСТВ.

The improvement of energetic and spectral characteristics of the satellite transmitters which act in the harsh space environment with the help of the predistortion linearization becomes more and more actual task. The proposed adaptive predistortion device is based on the correlation evaluation of the nonlinear distortion level at the output of the power amplifier. The device allows to provide more effective linearization in the conditions with changing characteristics of the satellite transmitter within the lifetime of the satellite at the orbit in difference to the systems with advance tuning. The proposed technical solution has a higher reliability and simplified technical implementation in comparison with the analogs due to lack of the preliminary analog and digital processing of the RF signal. The simplified algorithm which requires lesser logical capacity in the digital microcircuits than conventional adaptive algorithms was developed for the modeling of the adaptive predistortion device. The proposed algorithm of changing the parameters of the predistortion linearizer requires less mathematical calculations within one iteration cycle, which is based on the determination of the cross-correlation function gradient rise direction. The obtained results of proposed predistortion linearizer modeling show that the process of two-dimension adaptation based on the developed algorithm is monosemantic and leads to the recovery of the linearizer’s non-linear characteristics optimal tune. The adaptation process leads to the lowering of the intermodulation distortion at the output of the power amplifier in a few adaptation cycles. It is worth noting that the process of the optimization and selection of the two parameters of the predistortion linearizer in the amplifier flows the same way whatever if the analog of digital implementation of the linearizer is used.

A Survey on the Internet of Things (IoT) Forensics: Challenges, Approaches, and Open Issues

Today is the era of the Internet of Things (IoT). The recent advances in hardware and information technology have accelerated the deployment of billions of interconnected, smart and adaptive devices in critical infrastructures like health, transportation, environmental control, and home automation. Transferring data over a network without requiring any kind of human-to-computer or human-to-human interaction, brings reliability and convenience to consumers, but also opens a new world of opportunity for intruders, and introduces a whole set of unique and complicated questions to the field of Digital Forensics. Although IoT data could be a rich source of evidence, forensics professionals cope with diverse problems, starting from the huge variety of IoT devices and non-standard formats, to the multi-tenant cloud infrastructure and the resulting multi-jurisdictional litigations. A further challenge is the end-to-end encryption which represents a trade-off between users' right to privacy and the success of the forensics investigation. Due to its volatile nature, digital evidence has to be acquired and analyzed using validated tools and techniques that ensure the maintenance of the Chain of Custody. Therefore, the purpose of this paper is to identify and discuss the main issues involved in the complex process of IoT-based investigations, particularly all legal, privacy and cloud security challenges. Furthermore, this work provides an overview of the past and current theoretical models in the digital forensics science. Special attention is paid to frameworks that aim to extract data in a privacy-preserving manner or secure the evidence integrity using decentralized blockchain-based solutions. In addition, the present paper addresses the ongoing Forensics-as-a-Service (FaaS) paradigm, as well as some promising cross-cutting data reduction and forensics intelligence techniques. Finally, several other research trends and open issues are presented, with emphasis on the need for proactive Forensics Readiness strategies and generally agreed-upon standards.

Application of the Adaptive PI-Controller in the System of the Load Regulation of the Shearer

The article considers the question of replacing the classic PI controller in the shearer control system with an adaptive device, in which the regulator coefficients are adjusted depending on the random change in the re-sistance of coal to cutting. The classic PI controller in the control system has constant proportional and inte-gral coefficients. However, despite the ease of setup and practical implementation, as well as the relatively high robustness, this class of control devices cannot ensure the optimal functioning of the control system in all modes due to the nonlinearity of the control object and the random nature of the coal strength changing as the shearer moves in the coal face. To overcome these shortcomings, a neural network implementation of tuning the coefficients of the PI controller is proposed. The possibility of correcting the coefficients of the PI controller controlling the speed of movement of the shearer, with a random nature of changing the strength of coal, is proposed and experimentally proved. It is shown that the coefficients of the regulator vary according to a ra-ther complex law. It is proposed to use a neural network of the multilayer perceptron type as a corrector of the PI controller coefficients. Neural network training was carried out by the Levenberg-Marquardt method. The correctness of the results was confirmed by the results of computer modeling. It is shown that the use of a PI controller with a corrector in the form of a neural network in the control system will increase performance of the load regulator by an average of 1.5–3 times in comparison with the classical regulator. All this will allow to avoid critical overloads, and hence the possible breakdown of the mechanical parts in the transmission of the shearer in case of a sudden collision of the working body of the shearer with a solid inclusion. The pro-posed adaptive PI controller can be further used to improve the control system of the shearer, which is able to function effectively in various modes.

Tropical Modernity: A Hybrid-Construct in South China

Parallel to the discourse of Tropical Architecture and the work of UK architects in the British colonial territories in the Middle East, Africa, and India after the WWII, climate adaptation designs or devices such as brise-soleil, perforated cement bricks, sun shading screens, courtyards, etc., started to emerge in modernist buildings in Asia. This article is a preliminary survey of these cases in Hong Kong and Macau since the 1950s. It discusses how tropicality was used in response to the post-war revisionism of Modern Movement that placed emphasis on local identity and culture.

Wearable Adaptive Resistance Training Improves Ankle Strength, Walking Efficiency and Mobility in Cerebral Palsy: A Pilot Clinical Trial.

Goal: To determine the efficacy of wearable adaptive resistance training for rapidly improving walking ability in children with cerebral palsy (CP). Methods: Six children with spastic CP (five males, one female; mean age 14y 11mo; three hemiplegic, three diplegic; Gross Motor Function Classification System [GMFCS] levels I and II) underwent ten, 20-minute training sessions over four weeks with a wearable adaptive resistance device. Strength, speed, walking efficiency, timed up and go (TUG), and six-minute walk test (6MWT) were used to measure training outcomes. Results: Participants showed increased average plantar flexor strength (17 ± 8%, p = 0.02), increased preferred walking speed on the treadmill (39 ± 25%, p = 0.04), improved metabolic cost of transport (33 ± 9%, p = 0.03), and enhanced performance on the timed up and go (11 ± 9%, p = 0.04) and six-minute walk test (13 ± 9%, p = 0.04). Conclusions: The observed increase in preferred walking speed, reduction in metabolic cost of transport, and improved performance on clinical tests of mobility highlights the potentially transformative nature of this novel therapy; the rate at which this intervention elicited improved function was 3 – 6 times greater than what has been reported previously.

Mathematical model of jet control of adaptability of mine turbomachines

Achieving synergies from high-tech industries in combination with environmental technologies of innovative subsurface use is possible only on the path to the formation of a qualitatively new approach to creation of energy-efficient technologies including assistive technologies. The lack of adaptability of turbomachines providing industrial safety by more than 15% increases the cost of production of mining and oil and gas complexes of the Russian Federation, reducing their competitiveness due to their low energy efficiency. An equation is derived in the article for calculating the circulation of a circular lattice of aero-gas-dynamic profiles as a function of the energy parameters of the sources and vortex chambers drains associated with the energy efficiency of turbomachines. The dominant influence of jet control over the flow profiles of impeller blades is proved due to the energy characteristics of sources and drains, which are associated with the parameters of the mine network. Improving the methodology for the aerodynamic calculation of circular lattice of aerodynamic profiles and the development of radial aerodynamic schemes with increased adaptability made it possible to derive an absolutely unique vector for the future development of fan construction, fundamentally based on nature-like technologies for energy conversion and transfer. The possibility of a significant increase in aerodynamic loading, adaptability and efficiency of mine turbomachines, made according to radial aerodynamic schemes with vortex chambers built into the blades of the impeller, which perform the functions of adaptive inkjet circulation control devices, is proved. According to the results of the research, the VRVP-8 radial-vortex fan was created, which has 55% greater energy efficiency in relation to fans of the VME VV type. Currently, turbomachines are being developed based on nature-like technologies in relation to the oil and gas industry.

Buck converter with adaptive pass device employing capacitive and resistive power loss equalization

This paper presents a novel control technique to efficiently supply a wide range of output load current in a buck converter using an adaptive pass device at the output stage. The adaptive pass device segment size control technique is based on equalization of capacitive power loss and resistive power loss terms by taking into account load current, input supply voltage, temperature, process, and aging conditions; thus, leading to optimum efficiency at the output stage in a broad operating region. Power calculations are done in analog domain using a novel arithmetic cell called the adaptive gm stage. The additional power consumption introduced by the power calculation blocks is less than 1.4 μA, which enables high efficiency operation even in low load currents. The circuit and layout are designed in a standard 130 nm CMOS technology and simulation results show 5–35% efficiency increase for mid/low load currents compared to a fixed output stage buck converter. Compared to other reported adaptive pass device buck converters, 4% increase in peak power efficiency with 3× broader load current range has been achieved.

Impact of adaptive devices on horses, assisting persons, and riders with cerebral palsy in a therapeutic riding program

Hypothesis: The goal of this study was to evaluate the impact of three different adaptive devices used to facilitate therapeutic horseback riding for riders with cerebral palsy (CP), the horses, and the assisting persons. The study hypothesis was that there is no difference in clinical benefit to the rider; stress or physical saddle pressure to the horse; or the level of exertion required from assisting persons when using any of the three adaptive devices. Population: Individuals with varying disability due to cerebral palsy who participated in a therapeutic horseback riding program at a Professional Association of Therapeutic Horsemanship (PATH) Premier Accredited Center. Intervention: Therapeutic horseback riding sessions using one of three adaptive devices. Comparators: Two commonly used adaptive devices (English saddle and bareback pad with backrider), and one recently developed, less-used device (Independence saddle). Outcomes: Clinical benefit for the individual with Cerebral Palsy was evaluated using an osteopathic musculoskeletal exam score. Equine stress was evaluated using a horse stress behavior ethogram. Physical pressure under the saddle of the horse was evaluated using a Pliance Saddle pad under each adaptive device. Required level of exertion by assisting persons was measured using an assistant exertion score. Conclusion: Therapeutic riding using an English saddle, a backriding pad with backrider, or an Independence saddle, by individuals with various degrees of disability, does not cause excessive stress or result in excessive pressure to the horse. Using one assistive device over another also does not appear to change the likelihood of clinical benefit to the rider. However, exertion scores for assisting persons were lower when the Independence saddle was used compared to the English saddle or backriding pad. Adaptive devices that allow an individual with CP to improve function, ride more independently, provide some respite for the side walker and do not cause undue stress or frustration to the horse would be a great addition to the therapeutic regimen. Based on the results of this study, the Independence saddle is a viable alternative to the English saddle or the backriding pad for riders that would otherwise need extensive assisting person support in a therapeutic riding program.