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Growing demands for cleaner energy sources lead to innovations that require investigations in solar energy harvesting. Though numerous organic and inorganic photovoltaic devices have been explored for the solar power conversion, achieving a high efficiency is still an open challenge for the researchers. In this context, an efficient, self-adjusting solar power panel coupled with low-cost and high reliability is of great significance and demand. In this study, we investigate the potential of Shape Memory Alloy (SMA) actuators for solar tracking applications. Three SMA configurations were considered containing one and up to three SMAs arranged in parallel. The temperature range for the displacement experiments was 40°–60°. Additionally, three levels of mass were used, namely, 500 g, 600 g, and 700 g. The displacement experiments revealed that the addition of more SMAs into the configuration provided a more consistent performance. The force experiment revealed that two-SMA configuration achieved 60% higher force production compared to the one-SMA configuration under the same conditions while the three-SMA configuration was 31% higher than in the two-SMA configuration and 110% compared to the one-SMA configuration. Additionally, the force hysteresis of the two-SMA setup was smaller and closer to that of single-SMA configuration. The two-SMA configuration force hysteresis exhibited a more linear trend as compared to that of the three-SMA configuration. The outcomes of this work highlight the potential of using SMAs as actuators in solar-powered applications and that optimization in terms of the needed number of SMAs is required to meet the displacement and/or force requirements.Article Highlights: SMA actuators show promise for efficient solar tracking, with higher temperatures leading to increased displacement. Configurations with two SMAs perform comparably to those with three SMAs, offering a simpler design while maintaining effectiveness. Linear force trends and reduced hysteresis in two SMA configurations suggest easier system design and optimization for solar tracking applications. [ABSTRACT FROM AUTHOR]

Aluminium doped zinc oxide (AZO) nanomaterials (AlxZn1-xO) with x fraction varying as 0.02 and 0.04 were synthesized using the auto-combustion method using glycine as a fuel. The synthesized catalysts were characterized with X-ray diffraction (XRD), UV–Visible Spectroscopy (UV–Vis), Raman spectroscopy, Photoluminescence (PL) spectroscopy, and High Resolution Transmission Electron Microscopy (HR-TEM). XRD results showed that synthesized materials possessed good crystallinity, while UV–VIS was employed to find the band gaps of synthesized materials. Raman was used to determine the vibrational modes in the synthesized nanoparticles, while TEM analysis was performed to study the morphology of the samples. Industrial effluents such as indigo carmine and azo carmine G were used to test the photodegradation ability of synthesised catalysts. Parameters such as the effect of catalyst loading, dye concentration and pH were studied. The reduction in crystallite size, band gap and increased lattice strain for the 4% AZO was the primary reason for the degradation in visible irradiation, degrading 97 and 99% equimolar concentrations of indigo carmine and azo carmine G in 140 min. The Al doped ZnO was found to be effective in faster degradation of dyes as compared to pure ZnO in presence of natural sunlight. [ABSTRACT FROM AUTHOR]

Aggression in children is frequent during the early years of childhood. Among children with psychiatric disorders in general, and autism in particular, challenging behaviours and aggression rates are higher. These can take on different forms, such as hitting, kicking, and throwing objects. Social robots that are able to detect undesirable interactions within its surroundings can be used to target such behaviours. In this study, we evaluate the performance of five machine learning techniques in characterizing five possible undesired interactions between a child and a social robot. We examine the effects of adding different combinations of raw data and extracted features acquired from two sensors on the performance and speed of prediction. Additionally, we evaluate the performance of the best developed model with children. Machine learning algorithms experiments showed that XGBoost achieved the best performance across all metrics (e.g., accuracy of 90%) and provided fast predictions (i.e., 0.004 s) for the test samples. Experiments with features showed that acceleration data were the most contributing factor on the prediction compared to gyroscope data and that combined data of raw and extracted features provided a better overall performance. Testing the best model with data acquired from children performing interactions with toys produced a promising performance for the shake and throw behaviours. The findings of this work can be used by social robot developers to address undesirable interactions in their robotic designs. [ABSTRACT FROM AUTHOR]

Theoretically, it is more challenging to anticipate the conversion and selectivity of a photochemical experiment compared to thermally generated reactivity. This is due to the interaction of light with a photoreactive substrate. Photochemical reactions do not yet receive the same level of broad analytical study. Here, we close this research gap by presenting a methodology for statistically forecasting the time-dependent progression of photoreactions using widely available LEDs. This study uses NiS/ZnO in perovskite (MAPbI3) solar cells as an additive (5 volume %). The effect of monolithic perovskite solar cells (mPSCs) on forecasting the wavelength of LEDs has been carefully investigated using various characterization methods, including X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The photocatalytic activity was analyzed by measuring the voltage produced. Various factors like selectivity, stability and sensitivity were also examined. This work provides a new perspective to validate NiS/ZnO photocatalysts for predicting the wavelength of different light sources and to apply in photolithography. [ABSTRACT FROM AUTHOR]

The introduction of a practical solar cell by Bell Laboratory, which had an efficiency of approximately 6%, signified photovoltaic technology as a potentially viable energy source. Continuous efforts have been made to increase power conversion efficiency (PCE). In the present review, the advances made in solar cells (SCs) are summarized. Material and device engineering are described for achieving enhanced light absorption, electrical properties, stability and higher PCE in SCs. The strategies in materials and coating techniques for large area deposition are further elaborated, which is expected to be helpful for realizing high-efficiency SCs. The methods of light-harvesting in SCs via anti-reflecting coatings, surface texturing, patterned growth of nanostructure, and plasmonics are discussed. Moreover, progress in mechanical methods that are used for sun tracking are elaborated. The assistance of the above two protocols in maximizing the power output of SCs are discussed in detail. Finally, further research efforts needed to overcome roadblocks in commercialization were highlighted and perspectives on the future development of this rapidly advancing field are offered. [ABSTRACT FROM AUTHOR]

The quality of a companion robot's reaction is important to make it acceptable to the users and to sustain interactions. Furthermore, the robot's reaction can be used to train socially acceptable behaviors and to develop certain skills in both normally developing children and children with cognitive disabilities. In this study, we investigate the influence of reaction time in the emotional response of a robot when children display aggressive interactions toward it. Different interactions were considered, namely, pickup, shake, drop and throw. The robot produced responses as audible sounds, which were activated at three different reaction times, namely, 0.5 s, 1.0 s, and 1.5 s. The results for one of the tasks that involved shaking the robotic toys produced a significant difference between the timings tested. This could imply that producing a late response to an action (i.e. greater than 1.0 s) could negatively affect the children's comprehension of the intended message. Furthermore, the response should be comprehensible to provide a clear message to the user. The results imply that the designers of companion robotic toys need to consider an appropriate timing and clear modality for their robots' responses. [ABSTRACT FROM AUTHOR]

Social robots have gained a lot of attention recently as they have been reported to be effective in supporting therapeutic services for children with autism. However, children with autism may exhibit a multitude of challenging behaviors that could be harmful to themselves and to others around them. Furthermore, social robots are meant to be companions and to elicit certain social behaviors. Hence, the presence of a social robot during the occurrence of challenging behaviors might increase any potential harm. In this paper, we identified harmful scenarios that might emanate between a child and a social robot due to the manifestation of challenging behaviors. We then quantified the harm levels based on severity indices for one of the challenging behaviors (i.e. throwing of objects). Our results showed that the overall harm levels based on the selected severity indices are relatively low compared to their respective thresholds. However, our investigation of harm due to throwing of a small social robot to the head revealed that it could potentially cause tissue injuries, subconcussive or even concussive events in extreme cases. The existence of such behaviors must be accounted for and considered when developing interactive social robots to be deployed for children with autism. [ABSTRACT FROM AUTHOR]

Abstract: We report the synthesis and luminescence properties of the pure and Al-doped photosensitive ZnO films by microwave successive ionic layer adsorption reaction. The grain textured growth along c-axis in pure ZnO thin films and those doped with Al was studied by Energy-dispersive X-ray spectroscopy. The Al-doped films show high textured grain growth and high green emission intensity. The structural analysis of the thin films by X-ray diffraction along with scanning electron microscopy and its optical properties (photoluminescence) suggest creation of oxygen vacancy during doping which is responsible for the higher grain growth. The resistance measurements on the ZnO thin films reveal its significance in sensing and such films acts as good components of intelligent solar panels in which the electrical properties can be tuned by electron beam irradiation.Graphical abstract: [ABSTRACT FROM AUTHOR]

The effect of electron beam irradiation of dielectric and conductivity properties of nano ZnO-natural rubber (NR) disks was investigated here. It is revealed that electric properties such as AC conductivity, dielectric constant, and loss tangent of the irradiated samples were improved significantly as compared to the non-irradiated samples, which have been associated with defects in the composites. The total number of dipoles was generated inside the polymer matrix upon irradiation depends on the dislocations formed inside the matrix. From the experiments, we observe that in the amorphous region electron beam irradiation fetches crosslinking and breakdown at the same time. The enhancement of the dielectric and conductivity properties demonstrates that nano ZnO-NR disks will be a promising candidate for the optoelectronic industry. Finally, we also examined the influences of temperature on the electrical conductivity of irradiated samples. [ABSTRACT FROM AUTHOR]

Microwave-assisted successive ionic layer adsorption and reaction was employed to synthesize Sn-ZnO (tin-doped zinc oxide), and its sensitivity to ultraviolet radiation is compared with zinc oxide (ZnO). The sensing films were made by the dip-coated method on an indium titanium oxide glass substrate, and the sensing performance was monitored using the 300-700 nm wavelength of UV-Vis light. Excellent sensitivity and recovery were observed for the Sn-doped ZnO sensor device, especially at 380 nm wavelength of ultraviolet (UV) light (response and recovery time 2.26 s and 8.63 s, respectively, at 5 V bias voltage). The variation in photocurrent with respect to dark and light illumination atmosphere was well illustrated based on the Schottky and inter-particle network effects. Doping of Sn on ZnO nanoparticles varied the surface roughness and crystallite size as observed from scanning electron microscopic and x-ray diffraction studies. Here, we demonstrate a simple and economical fabrication technique for designing a high-performance UV light sensor. The developed device works at room temperature with high durability and stability. [ABSTRACT FROM AUTHOR]

The present study deals with the development of a chemical sensor for the detection of liquefied petroleum gas (LPG) at a low operating temperature using Zinc ferrite (ZnFeO)/ Bacillus subtilis ( B. subtilis) hybrid nanostructures. The nanostructure ZnFeO and B. subtilis powder, taken in equal proportion was made into films using the spin coating technique. X-ray diffraction, thermal analysis, scanning electron microscopy, and transmission electron microscopy were used to study morphology, structure and crystallite size. The sensing properties of the hybrid structure were studied and excellent response was observed in the temperature range of 50-55°C for 400 ppm LPG, when compared to the individual components of the hybrid. The signal output of the proposed sensor were extremely stable for more than 30 days. This method proposes the usage of the biomolecule/metal oxide composites in electronics and helps to reduce the metal oxide usage. [ABSTRACT FROM AUTHOR]

Al-doped polycrystalline nano ZnO (Al-ZnO) thin films with different doping concentrations were successfully prepared by the microwave-assisted successive ionic layer adsorption and reaction (mSILAR) technique. The structural analysis along with the orientation of the prepared films was examined by powder x-ray diffraction (PXRD) patterns. The deposited film is polycrystalline and the (002) orientation enhanced upon doping. Additional investigations were carried out to study the effect of electron beam irradiation (e-irradiation) on the band gap and photoconductivity of both irradiated and unirradiated samples. Both the Al doping and e-irradiation led to the enhancement of the photoconductivity of prepared materials. This property enables us to tune the properties of materials for various applications by controlling dopant concentrations and e-irradiation. The dependence of photocurrent on e-irradiation of Al-ZnO thin films was not reported previously. Therefore, Al-doped polycrystalline nano-ZnO thin film is a promising material for band gap engineering and for the development of solar cells. [ABSTRACT FROM AUTHOR]

For efficient social interactions, humans have developed means to predict and understand others' behavior often with reference to intentions and desires. To infer others' intentions, however, one must assume that the other is an agent with a mind and mental states. With two experiments, this study examined if the human perceptual system is sensitive to detecting human agents, based on only subtle behavioral cues. Participants observed robots, which performed pointing gestures interchangeably to the left or right with one of their two arms. Onset times of the pointing movements could have been pre-programmed, human-controlled (Experiment 1), or modeled after a human behavior (Experiment 2). The task was to determine if the observed behavior was controlled by a human or by a computer program, without any information about what parameters of behavior this judgment should be based on. Results showed that participants were able to detect human behavior above chance in both experiments. Moreover, participants were asked to discriminate a letter (F/T) presented on the left or the right side of a screen. The letter could have been either validly cued by the robot (location that the robot pointed to coincided with the location of the letter) or invalidly cued (the robot pointed to the opposite location than the letter was presented). In this cueing task, target discrimination was better for the valid versus invalid conditions in Experiment 1 where a human face was presented centrally on a screen throughout the experiment. This effect was not significant in Experiment 2 where participants were exposed only to a robotic face. In sum, present results show that the human perceptual system is sensitive to subtleties of human behavior. Attending to where others attend, however, is modulated not only by adopting the Intentional Stance but also by the way participants interpret the observed stimuli. [ABSTRACT FROM AUTHOR]

Earlier theorizing suggested that an (artificial) agent that combines persuasive strategies will be more persuasive. Therefore, the current research investigated whether a robot that uses two persuasive strategies is more persuasive than a robot that uses only one. Two crucial persuasive strategies that humans use in face-to-face persuasion are gazing and gestures, and therefore we studied the combined and individual contribution of these two persuasive strategies (gestures and gazing) on the persuasiveness of a storytelling robot. A robot told a classical persuasive story about the consequences of lying to forty-eight participants, and was programmed to use (persuasive) gestures (or not) and gazing (or not). Next, we asked participants to evaluate the character in the story thereby assessing the robot's persuasiveness. Results presented evidence a robot's persuasiveness is increased when gazing is used. When the robot used gestures, its persuasiveness only increased when it also used gazing. When the robot did not use gazing, using gestures diminished the robot's persuasiveness. We discuss the implications for theory and design of robots that are more persuasive. [ABSTRACT FROM AUTHOR]

This paper reviews the use of socially interactive robots to assist in the therapy of children with autism. The extent to which the robots were successful in helping the children in their social, emotional and communication deficits was investigated. Child-robot interactions were scrutinized with respect to the different target behaviors that are to be elicited from a child during therapy. These behaviors were thoroughly examined with respect to a child's development needs. Most importantly, experimental data from the surveyed works were extracted and analysed in terms of the target behaviors and of how each robot was used during a therapy session to achieve these behaviors. The study concludes by categorizing the different therapeutic roles that these robots were observed to play, and highlights the important design features that enable them to achieve high levels of effectiveness in autism therapy. [ABSTRACT FROM AUTHOR]

This paper aimed to explore whether human beings can understand gestures produced by telepresence robots. If it were the case, they can derive meaning conveyed in telerobotic gestures when processing spatial information. We conducted two experiments over Skype in the present study. Participants were presented with a robotic interface that had arms, which were teleoperated by an experimenter. The robot can point to virtual locations that represented certain entities. In Experiment 1, the experimenter described spatial locations of fictitious objects sequentially in two conditions: speech only condition (SO, verbal descriptions clearly indicated the spatial layout) and speech and robotic gesture condition (SR, verbal descriptions were ambiguous but accompanied by robotic pointing gestures). Participants were then asked to recall the objects' spatial locations. We found that the number of spatial locations recalled in the SR condition was on par with that in the SO condition, suggesting that telerobotic pointing gestures compensated ambiguous speech during the process of spatial information. In Experiment 2, the experimenter described spatial locations non-sequentially in the SR and SO conditions. Surprisingly, the number of spatial locations recalled in the SR condition was even higher than that in the SO condition, suggesting that telerobotic pointing gestures were more powerful than speech in conveying spatial information when information was presented in an unpredictable order. The findings provide evidence that human beings are able to comprehend telerobotic gestures, and importantly, integrate these gestures with co-occurring speech. This work promotes engaging remote collaboration among humans through a robot intermediary. [ABSTRACT FROM AUTHOR]

The artificial hands for sociable robotics and prosthetics are expected to be touched by other people. Because the skin is the main interface during the contact, a need arises to duplicate humanlike characteristics for artificial skins for safety and social acceptance. Towards the goal of replicating humanlike social touch, this paper compares the skin compliance, conformance and hysteresis of typical robotic and prosthetic skin materials, such as silicone and polyurethane, with the published biomechanical behavior of the human fingertip. The objective was achieved through materials characterization, finite element (FE) modeling and validation experiments. Our initial attempt showed that the selected types of silicone and polyurethane materials did not exhibit the same qualities as the human fingertip skin. However, the methodologies described herein can be used to evaluate other materials, their possible combinations or other fingertip design configurations. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including emphatic robots, interactions between humans and robots, and robots in social services.

The article discusses various reports published within the issue including one by Laura Boccanfuso and Jason M. O'Kanbe about an adaptive robot design, Isao Fujimoto and colleagues on the use of assistive robot for improving imitation skill of children with autism and Yuto Yamaji and colleagues on child-robot interaction.