Robot-Fish Interaction Helps to Trigger Social Buffering in Neon Tetras: The Potential Role of Social Robotics in Treating Anxiety

The emerging field of social robotics comprises several multidisciplinary applications. Anxiety and stress therapies can greatly benefit by socio-emotional support provided by robots, although the intervention of social robots as effective treatment needs to be fully understood. Herein, Paracheirodon innesi, a social fish species, was used to interact with a robotic fish to understand intrinsic and extrinsic mechanisms causing anxiety, and how social robots can be effectively used as anxiety treatments. In the first experiment we tested the effects of a conspecific-mimicking robot on the fish tendency to swim in the bottom when transferred in a new tank. Here, P. innesi spent a significantly longer time in the upper section of the test tank when the robotic fish was present, clearly indicating a reduction of their state of anxiety due to social stimuli. The second experiment was based on a modification of the dark/light preference test, since many teleost fish are scototactic, preferring dark environments. However, when the robotic fish was placed in the white half of the test tank, P. innesi individuals swam longer in this section otherwise aversive. Social support provided by the robotic fish in both experiments produced a better recovery from anxiety due to social buffering, a phenomenon regulated by specific neural mechanisms. This study provides new insights on the evolution and mechanisms of social buffering to reduce anxiety, as well as on the use of social robots as an alternative to traditional approaches in treating anxiety symptoms.

Three decades of oxygen transfer tests in clean water in a pilot scale test tank with fine-bubble diffusers and the resulting conclusions for WWTP operation

We summarized the experience from three decades of oxygen transfer testing and aeration research at the Technical University of Darmstadt to validate the oxygen transfer efficiency of modern fine-bubble diffusers. A total of 306 oxygen transfer tests in clean water of 65 different fine-bubble diffusers, carried out in the same test tank under identical test conditions, were analysed and compared with previous results. As a result, we could show that the performance of fine-bubble aeration systems has increased by 17% over the last three decades. Therefore, modern well-designed and operated aeration systems can achieve specific standard oxygen transfer efficiency (SSOTE) values between 8.5 and 9.8% · m−1. Additionally, a comparison of various diffuser types and diffuser densities was done. Based on the new results, an exemplary cost/benefit analysis for a 100,000 PE WWTP shows the calculation of an optimized diffuser density with respect to investment and operating costs.

On the Use of a Single Beam Acoustic Current Profiler for Multi-Point Velocity Measurement in a Wave and Current Basin

Harnessing the energy of tidal currents has huge potential as a source of clean renewable energy. To do so in a reliable and cost effective way, it is critical to understand the interaction between tidal turbines, waves, and turbulent currents in the ocean. Scaled testing in a tank test provides a controlled, realistic, and highly reproducible down-scaled open ocean environment, and it is a key step in gaining this understanding. Knowledge of the hydrodynamic conditions during tests is critical and measurements at multiple locations are required to accurately characterise spatially varying flow in test tank facilities. The paper presents a laboratory technique using an acoustic velocimetry instrument, the range over-which measurements are acquired being more akin to open water applications. This enables almost simultaneous multi-point measurements of uni-directional velocity along a horizontal profile. Velocity measurements have been obtained from a horizontally mounted Single Beam Acoustic Doppler (SB-ADP) profiler deployed in the FloWave Ocean Energy Research Facility at the University of Edinburgh. These measurements have been statistically compared with point measurements obtained while using a co-located Acoustic Doppler Velocimeter (ADV). Measurements were made with both instruments under flow velocities varying from 0.6 ms−1 to 1.2 ms−1, showing that flow higher than 1 ms−1 was more suitable. Using a SB-ADP has shown the advantage of gaining 54 simultaneous measurement points of uni-directional velocity, covering a significant area with a total distance of 10 m of the test-tank, at a measurement frequency of 16 Hz. Of those measurement points, 41 were compared with co-located ADV measurements covering 8 m of the profile for a tank nominal flow velocity of 0.8 ms−1, and four distributed locations were chosen to to carry out the study at 0.6 ms−1, 1.0 ms−1, and 1.2 ms−1. The comparison with the ADV measurement showed a 2% relative bias on average.

Use of Reclaimed Rubber Cell in Highway Pavement: An Experimental Research

With the rapidly growing number of vehicles around the world, the disposal of the waste and discarded tyres is a serious concern worldwide. There are few investigations reported in the literature w.r.t. the use of the regenerated rubber derived from the waste tyres in the construction of pavements. The highway construction forms a potential sector for the use of such waste whereby the problem of its disposal will get eliminated on one hand and reduce the environmental concern on the other hand. The use of such waste is found to improve the performance and strength of the pavement. This paper presents the limited experimental investigations on the use of innovative reinforcement in the form of rubber cell derived from the regenerated or reclaimed tyres in the pavement application. The rubber cell derived is similar to conventional geocell. The experimental study entails the use of the rubber cell placed within the conventional granular sub-base (GSB) of the conventional flexible pavement through a model pavement. The laboratory model tests were conducted with the help of the test tank of dimensions (1 m × 1m × 1m). The sub-base was placed above the weak subgrade in a test tank. The results of the laboratory model tests indicates the better performance of the pavement with the use of the rubber cell in the sub-base as compared to the performance of the pavement with conventional granular subbase without rubber cell reinforcement. The study confirms the effective utilization of the discarded tyres as a reinforcing material in the pavements.

Measurement of impedance and sensitivity of electroacoustic transducers

In the paper a methodology is presented for electroacoustic transducer impedance and transmitting sensitivity measurement. Loaded transducer electrical impedance is measured in water test tank. The methodology for measurement of transmitting sensitivity is based on the pulse method. Experimental results are presented for measured impedance and sensitivity of piezoceramic disc transducer in water filled test tank.

Study on Flexural Properties of Tubular Underwater Inflated Structures Filled with Hydrogel Beads

Underwater inflatable structures (UISs) are distributed in an initial folded state for ease of transportation and deployment. They are able to morph into their intended geometry upon arrival at their destination. This morphing/inflation process can be driven by hydrogel beads, which swell when they contact water. In this research, we study the physical characteristics of tubular UISs with different configurations (length, slenderness, beads density). We fabricated sets of tubular UISs with nylon sleeves filled with different amounts of hydrogel beads and built a flexural test platform mounted on the test tank for the bending experiment. This work provides the experimental Young’s modulus of the tubular UISs under elastic and plastic deformations, and also discusses how the different configurations contribute to the tubular UIS’s stiffness.

Experimental study of hydrodynamic forces acting on ship bow during wave capture

This paper studies behavior of ship in head waves, when her bow dips under water, which leads to hydrodynamic forces and moments to be assessed. This paper presents model test data obtained in the test tank on the model of ship bow (hydrodynamic loads on forecastle deck during wave capture) as well as updates the coefficient of flow around the bow. The study also shows that bulwark has negative effect upon safety in these conditions because it significantly increases hydrodynamic loads on the deck.