Foam Ball Research Articles

Action observation and imitation: Corticospinal responses and hemispheric dominance

Abstract The response of the motor neuron system to the observation of lateralized movements and expectation mismatches remains elusive. We investigated how observation of hand movement modulates corticospinal excitability as measured by motor evoked potentials to single pulse transcranial magnetic stimulation (TMS). Twenty-seven adults watched a series of egocentric video recordings of hands, with one hand either squeezing a foam ball as expected or both hands remaining stationary. Task conditions comprised observation-only and observation with synchronous imitation of the depicted motor action. Single TMS pulses were delivered to the motor cortex contralateral to the dominant hand at the video frame of maximal hand closure for squeeze videos and randomly for no-squeeze videos (in both observation-only or observation with synchronous imitation). We analyzed MEPs, from the First Dorsal Interosseous (FDI) muscle of the dominant hand. Observation alone (absence of motor intention) did not enhance corticospinal excitability; however, when paired with imitation (presence of motor intention), it tended to increase MEP amplitudes, regardless of the attended side (dominant or non-dominant) or depicted action (squeeze or not). Among conditions in which the dominant hand remained stationary, MEP amplitudes were elevated (p = 0.004) in observation with imitation of non-dominant hand squeezing, suggesting hemispheric dominance in coordinating motor actions. Additionally, MEP latencies tended to decrease during synchronous imitation of squeeze videos. Our findings support the consideration of observation with synchronous imitation as a task for brain state-dependent brain stimulation protocols for optimizing neuromotor recovery.

Sexual dimorphism and the impact of aging on ball rolling-associated locomotor behavior in Drosophila.

Insects exhibit a remarkable ability to interact with inanimate objects to facilitate essential behaviors such as foraging, reproduction, shelter building, and defense. In this study, we assessed whether Drosophila interacted with inanimate objects when they were suspended on their wings and provided with a thermocol ball (foam ball). Drosophila indeed exhibited ball rolling behavior. We further examined the sexual dimorphism in this ball rolling-associated locomotor behavior. We carried out a ball rolling assay using 3-day-old male and female w1118 flies and measured the duration for which the flies could roll the ball without dropping it within a 10 min period. The ball was returned to the flies whenever they dropped it, and we calculated the number of times the ball was dropped within the 10 min duration. Females exhibited a longer ball holding duration than males. We also observed a decrease in ball holding duration and an increase in the number of times the ball was dropped by 15-day-old male and female flies than their younger counterparts. These results suggest sexual dimorphism and age-dependent alterations in Drosophila ball rolling-associated locomotor behavior.

Spherical Design‐Driven Scalable Solar‐Powered Water Treatment with Salt Self‐Cleaning and Light Self‐Adaptivity

AbstractInterfacial solar evaporation, harnessing sunlight to induce water molecule evaporation, holds great promise for sustainable solar energy conversion. However, challenges such as reduced efficiency and instability due to salt accumulation, inadequate water transport, and the high cost of advanced nanostructured solar evaporators collectively hinder the sustainable and large‐scale practical use of this technology. Herein, an eco‐friendly, floatable 3D solar seawater evaporator is developed by innovatively incorporating a lightweight foam ball enclosed in a porous cellulose hydrogel. The 3D evaporator achieves a high water evaporation rate of ≈2.01 kg m−2 h−1 under 1 Sun, owing to its super high photothermal efficiency of 117.9% and efficient internal water transport channels. Even at a 0° simulated solar angle, the 3D evaporator maintains 85.8% of the evaporation rate at a 90° simulated solar angle. Moreover, the salt self‐cleaning capability is realized by the autonomous rotation caused by salt deposition. Particularly, the 3D evaporator can be fabricated over a large area and maintain seawater evaporation performance and structural integrity for 28 days. This study provides novel economically feasible and sustainable large‐scale solutions for interfacial solar‐powered seawater treatment.

Study on the Characteristics of Downwash Field Range and Consistency of Spray Deposition of Agricultural UAVs

Agricultural unmanned aerial vehicles (UAVs), increasingly integral to crop protection through spraying operations, are significantly influenced by their downwash fields, which in turn affect the distribution of spray droplets. The key parameters impacting spray deposition patterns are the velocity of the downwash airflow and its spatial extent. Understanding the interplay of these parameters can enhance the efficacy of UAV applications in agriculture. Previous research has predominantly focused on downwash airflow velocity, often neglecting the spatial scope of the downwash. This paper presents an applied foundational study grounded in the compressible Reynolds-averaged Navier–Stokes (RANS) equations. Leveraging a dependable k-ε turbulence model and dynamic mesh technology, it develops an effective three-dimensional computational fluid dynamics (CFD) approach to analyze the downwash field’s distribution characteristics during UAV hover. To validate the CFD method, a visualization test was conducted using EPS (expanded polystyrene foam) balls dispersed in the airspace beneath the UAV, illustrating the airflow’s spatial distribution. Additionally, a parameter η was introduced to quantify changes in the wind field’s range, enabling the mapping of the cross-sectional area of the downwash airflow at various velocities within the UAV’s airspace. The study reveals that the downwash field’s overall shape evolves from a “four-point type” to a “square-like” and then to an “ellipse-like” configuration. Lower downwash airflow velocities exhibit a more rapid expansion of the wind field area. High-velocity downwash areas are concentrated beneath each rotor, while lower-velocity zones coalesce under each rotor and extend downward, forming a continuous expanse. Within the UAV’s downwash area, the deposition of droplets is more pronounced. At a given nozzle position, an increase in downwash airflow velocity correlates with greater droplet deposition within the downwash field. This research bridges a gap in downwash field studies, offering a solid theoretical foundation for the development of future UAV downwash field models.

Development of a Two-Finger Haptic Robotic Hand with Novel Stiffness Detection and Impedance Control.

Haptic hands and grippers, designed to enable skillful object manipulation, are pivotal for high-precision interaction with environments. These technologies are particularly vital in fields such as minimally invasive surgery, where they enhance surgical accuracy and tactile feedback: in the development of advanced prosthetic limbs, offering users improved functionality and a more natural sense of touch, and within industrial automation and manufacturing, they contribute to more efficient, safe, and flexible production processes. This paper presents the development of a two-finger robotic hand that employs simple yet precise strategies to manipulate objects without damaging or dropping them. Our innovative approach fused force-sensitive resistor (FSR) sensors with the average current of servomotors to enhance both the speed and accuracy of grasping. Therefore, we aim to create a grasping mechanism that is more dexterous than grippers and less complex than robotic hands. To achieve this goal, we designed a two-finger robotic hand with two degrees of freedom on each finger; an FSR was integrated into each fingertip to enable object categorization and the detection of the initial contact. Subsequently, servomotor currents were monitored continuously to implement impedance control and maintain the grasp of objects in a wide range of stiffness. The proposed hand categorized objects' stiffness upon initial contact and exerted accurate force by fusing FSR and the motor currents. An experimental test was conducted using a Yale-CMU-Berkeley (YCB) object set consisted of a foam ball, an empty soda can, an apple, a glass cup, a plastic cup, and a small milk packet. The robotic hand successfully picked up these objects from a table and sat them down without inflicting any damage or dropping them midway. Our results represent a significant step forward in developing haptic robotic hands with advanced object perception and manipulation capabilities.

Experimental study on the effect of basalt fiber reinforced expanded polystyrene foams on the compressive strength of lightweight concrete

Reducing the structural load and operational energy consumption of buildings is a trend in the development of the construction industry, and lightweight concrete has become a research hotspot because of its dual characteristics of low density and high strength. In this paper, a three-step method is used to prepare lightweight concrete composites. In the first step, basalt fiber powder was adhered to polystyrene foam ball expanded polystyrene spheres (EPSs) by the “ball rolling method” to obtain basalt fiber reinforced epoxy composite balls. In the second step, the epoxy resin composite ball and the configured cement matrix are filled into a prefabricated mold. Finally, the lightweight concrete specimens were overlaid, pressed into shape, and cured for 28 days. By changing the volume ratio, size, and wall thickness of the epoxy composite balls, as well as the length and content of basalt fibers, the lightweight concrete was exhibited a reduction in density and increase in strength. The results showed that the smaller the epoxy composite spheres and the larger the wall thickness are, the higher the compressive strength of the material for a certain volume ratio of epoxy composite spheres will be. The addition of appropriate hollow glass beads can reduce the number of pores in the matrix, but excessive hollow glass beads will reduce the bonding force of the concrete matrix. Basalt fibers not only improve the strength of EPSs but also serve to connect matrix–matrix and matrix–epoxy composite spheres.

Efficiently harvesting low-speed wind energy by a novel bi-stable piezoelectric energy harvester from vortex-induced vibration and galloping

Efficiently harvesting low-speed wind energy by a novel bi-stable piezoelectric energy harvester from vortex-induced vibration and galloping

Soil contamination by plastic particles in the floodplain of the small Danilikha River in an urbanized area

The aim of the study. To assess the content, morphology and surface degradation degree of plastic particles in the Danilikha river floodplain soils in an urbanized area. Location and time of the study. The study was conducted in a recreational area in the projected “Kamensky Square”, located on the left bank of the low floodplain of the small Danilikha River (a left-bank tributary of the Kama River) in the city of Perm. Urban-alluvial gray-humus gley soils were identified in the area. Soil samples were taken from surface horizons in July 2023. Methods. To extract plastic particles from soil we used visual selection, sieving, and flotation in a saturated NaCl solution. The shape and type of plastic particles were determined visually by external features. Natural organic matter was removed with Fenton's reagent. Surface morphology of the of plastic particles and their number were determined using a stereomicroscope. Information-logical analysis was used to determine the relationship between the shape of plastic particles and their sizes. Results. In the combined soil sample from the surface horizons, the number of plastic particles reached 177 pieces/kg (excluding fibers). The mass of plastic particles, including fibers, was 0.7 g/kg. Films prevailed quantitatively among the forms of plastic particles (62%), whereas foam and foam balls made up 34% and 4%, respectively. By mass, particles predominated in the following sequence: foam balls ˃ film ˃ fiber ˃ foam. The size range was dominated by large plastic particles from 1.1 to 15 mm. Specific sizes of plastic particles for different shapes were established. Conclusions. For the first time, the content of plastic particles in the surface soil horizons of the Danilikha river floodplain in an urbanized territory was studied using the case of a recreational zone in the projected Kamensky Square. Plastic particles had different sizes and shapes, which indicated a variety of contamination sources. Contamination of the studied soils with plastic particles can be regarded as moderate. The surface degradation degree of plastic particles indicated their active weathering, which occurs in soil under neutral reaction. The surface degradation of the plastic particles was also actively influenced by external factors that act before plastics enter alluvial soils. To detect soil contamination with plastic particles, we recommend Perm municipal authorities to organize monitoring of plastics content in areas with high anthropogenic pressure.

Transverse Particle Trapping Using Finite Bessel Beams Based on Acoustic Metamaterials

We investigate the transverse trapping force acting on a small particle on or off the central axis of zero-order finite Bessel beams. Combining the simulated fields with the Gorkov force potential, the transverse trapping behaviors for small objects are analyzed, and the reversal of the trapping behaviors is recovered when varying the paraxiality parameter of the Bessel beam. The results prove the possibility of using axisymmetric Bessel beams to trap both dense and stiff particles as well as light and soft ones. The particles can be trapped at the maximum central pressure in the main lobe and also the maximum pressure of the other transverse locations. A lossy acoustic metastructure with the ability to decouple the phase and amplitude modulations is used to generate the desired sound field, which is used to trap a foam ball as an example. Our research opens a promising avenue to the design and development of simplified acoustic tweezers.

Thermo-Convective Flows of Mono- and Hybrid-Nanofluids Over Horizontal Undulated Surfaces in a Porous Medium

This paper presents a comparative study between the thermo-convective flows of two mono- and one hybrid-nanofluid over three uniformly heated undulated surfaces (described by sinusoidal, sawtooth or triangular waveforms) embedded in a porous medium. The base fluid for each nanofluid is water, and the nanoparticles are copper, alumina or a copper-alumina mixture. Two different types of materials of the porous medium have been considered: aluminum foam and glass balls. This problem is governed by a system of nonlinear, coupled partial differential equations, which is solved using the Keller-Box method. The influences of each porous medium and the pertinent parameters on the nanofluid flows and heat transfer have been explored. It is seen that secondary flow occurs at large amplitudes of the surface undulations for the sinusoidal and triangular waveforms, but no such flow is observed in the case of the sawtooth waveform and the flat surface. To assess the heat transfer properties, the mean Nusselt number has been calculated. It is observed that the mean Nusselt number is higher in the porous medium of glass balls than aluminum foam. The heat transfer on the undulated surfaces is the highest in the case of a hybrid-nanofluid and the least for water-alumina.

Some features of the structural systems of houses built from materials

This paper discusses the technological and design features of houses built from local clay materials, in particular, those built from a wooden frame filled with clay materials called “synch” and from adobe or clay materials of irregular shape “pakhsa”. Such buildings built from local materials, as a rule, related to buildings with walls made of low-strength materials, were mostly erected without observing technological, anti-seismic measures and are characterized as the most vulnerable in seismic terms. A comparative analysis of the technology of erection by the owners themselves with some violations and the technology of erection proposed by us in compliance with the rules during the construction process was carried out. In houses built using the “synch” technology, foam balls (expanded polystyrene) were used as a filler to reduce the mass of clay, the optimal ratio of clay and expanded polystyrene was revealed, in the course of research we received a patent for a modified clay material with expanded polystyrene. And also, the results of testing models of houses built from a wooden frame filled with clay materials (synch) and from clay materials using the “pakhsa” technologies are given.

Unsteady natural convection of nano-encapsulated phase change materials (NEPCMs) inside a random porous medium considering local thermal non-equilibrium condition

A local thermal non-equilibrium analysis is undertaken to simulate unsteady free convective heat transfer inside a square enclosure filled with a random porous medium. There is a time-varying temperature profile at the hot wall. The fluid is a suspension comprising nano-encapsulated phase change materials (NEPCM) particles dispersed in water while aluminum foam, copper foam, or glass balls are considered for the solid matrix. It is found that when the hot wall temperature reaches its minimum value during one oscillation period, most of the cavity is occupied by the NEPCM particles in the solidious phase. For the metallic foams, the heat transfer of the medium is substantially higher than the NEPCM particles. Meanwhile, the Nusselt number of the glass balls is much lower than the suspension. A rise in the dimensionless frequency or amplitude of the temperature profile as well as approaching the dimensionless fusion temperature to 0.5 elevates Nusselt number of the suspension. However, no general conclusion can be drawn for their consequences on the heat transfer in the solid matrix. Among the current alterable parameters, only the contributions of the non-dimensional interface heat transfer coefficient and the non-dimensional amplitude of the temperature profile are found significant.

Triggering star formation: Experimental compression of a foam ball induced by Taylor–Sedov blast waves

The interaction between a molecular cloud and an external agent (e.g., a supernova remnant, plasma jet, radiation, or another cloud) is a common phenomenon throughout the Universe and can significantly change the star formation rate within a galaxy. This process leads to fragmentation of the cloud and to its subsequent compression and can, eventually, initiate the gravitational collapse of a stable molecular cloud. It is, however, difficult to study such systems in detail using conventional techniques (numerical simulations and astronomical observations), since complex interactions of flows occur. In this paper, we experimentally investigate the compression of a foam ball by Taylor–Sedov blast waves, as an analog of supernova remnants interacting with a molecular cloud. The formation of a compression wave is observed in the foam ball, indicating the importance of such experiments for understanding how star formation is triggered by external agents.

Design and complexity evaluation of a self-cleaning heat exchanger

Self-engineering (SE) systems have valuable abilities to register and respond to lost function and return it. A self-cleaning (SC) system was designed for effective automated cleaning of a heat exchanger (HX) fouled by brewing wort. The system uses temperature outputs in a Digital Twin (DT) simulation and a controller to identify when fouling occurs and trigger a cleaning response. This paper utilises the SE complexity framework and investigates the effectiveness of different complexity designs. Three levels are created for each factor of the framework (repeatability, redundancy and self-control). For repeatability, the number of cleaning cycles was changed, while for redundancy, the flow rate was changed. For self-control, the cleaning mechanism was changed; pulses and foam balls were both used as the cleaning mechanisms. Balls were used to block pipes and redirect flow. An orthogonal matrix is used to reduce the number of experiments. SC effectiveness was measured for each cleaning cycle, and the results were evaluated. Cleaning with the max flow rate (0.21 kg s−1) and using balls and pulses together provided the most effective cleaning, while the worst was with a low flow rate (0.09 kg s−1) and just pulses. Further experiments verified these results and showed that better cleaning settings could lower water use in cleaning. A longer simulation demonstrated when the SC system would be stopped.

Fabrication and Mechanical Performance of Glass Fiber Reinforced, Three‐phase, Epoxy Syntactic Foam

AbstractIn the selection of materials for deep‐sea equipment, light weight and high strength are the most important criteria or requirements. In this paper, hollow glass microspheres (HGMS), expanded polystyrene (EPS), epoxy resin (EP) and curing agent were mixed to prepare hollow glass microspheres reinforced epoxy foam balls (HGMS‐EHS) by the rolling ball method. Glass fiber (GF) reinforced epoxy syntactic foam (GF‐ESF) was prepared by mixing HGMS‐EHS, HGMS, EP, GF, and curing agent using compression moulding method. By analyzing the mechanical properties and microscopic morphology of GF‐ESF, the results show that the addition of GF does enhance the compressive strength of epoxy syntactic foam. GF‐ESF has a density of 496 kg/m3, and its compressive strength is 30.48 MPa. By increasing the number of layers of HGMS‐EHS, the diameter of EPS, the density of HGMS and reducing the stacking volume of HGMS‐EHS, the density of ESF increased significantly thus subsequently increase the compressive strength. Therefore, the compressive strength and density should be considered comprehensively and find the best balance point in the process of preparing ESF. This paper could provide some suggestions for the preparation of deep‐sea epoxy composites.

Sex Differences in the Mechanical and Neurophysiological Response to Roller Massage of the Plantar Flexors.

Self-massage using foam rollers, sticks, or balls has become a popular technique to enhance joint range of motion (ROM). Although increases are reported to be larger in females than males, the mechanisms of this observation are unclear. The present study aimed to investigate the effect of roller massage (RM) on ROM, passive tissue stiffness, and neurophysiological markers as a function of sex. Males (n = 15, 22.8 ± 2.9 yrs.) and females (n = 14, 21.1 ± 0.7 yrs.) performed three 60-second bouts of calf RM. Outcomes assessed pre-, and post-intervention included passive dorsiflexion (DF) ROM, passive tissue stiffness, passive torque, DF angle at the first stretch sensation, shear elastic modulus, and spinal excitability. DF ROM (+35.9 %), passive torque at DF ROM (+46.4 %), DF angle at first stretch sensation (+32.9 %), and pain pressure threshold (+25.2 %) increased in both groups (p<.05) with no differences between males and females (p > 0.05). No changes were observed for passive stiffness, shear elastic modulus, and spinal excitability (p > 0.05). Roller massage may increase ROM independently of sex, which, in the present study, could not be ascribed to alterations in passive stiffness or neurophysiological markers. Future studies may further elucidate the role of sensory alterations as possible factors driving RM-induced changes in flexibility.

Possible limitations of dolphin echolocation: a simulation study based on a cross-modal matching experiment

Dolphins use their biosonar to discriminate objects with different features through the returning echoes. Cross-modal matching experiments were conducted with a resident bottlenose dolphin (Tursiops aduncus). Four types of objects composed of different materials (water-filled PVC pipes, air-filled PVC pipes, foam ball arrays, and PVC pipes wrapped in closed-cell foam) were used in the experiments, respectively. The size and position of the objects remained the same in each case. The data collected in the experiment showed that the dolphin’s matching accuracy was significantly different across the cases. To gain insight into the underlying mechanism in the experiments, we used finite element methods to construct two-dimensional target detection models of an echolocating dolphin in the vertical plane, based on computed tomography scan data. The acoustic processes of the click’s interaction with the objects and the surrounding media in the four cases were simulated and compared. The simulation results provide some possible explanations for why the dolphin performed differently when discriminating the objects that only differed in material composition in the previous matching experiments.

A study on damping ratio of EPS foam filled CFRP composite tubes

AbstractThis study aims to investigate the damping behavior of the fundamental mode of a foam-filled carbon fibre reinforced polymer composite (CFRP) tube when subjected to base excitations. In particular, expanded polystyrene (EPS) foam balls (with negligible mass) of different sizes are used as fillers in the tube and the enhancement in damping ratio of the fundamental mode w.r.t the empty condition is evaluated for different intensity of base excitation. Shake table tests are performed on cantilever CFRP composite square hollow tube subjected to base excitation with varying amplitudes. The tube is filled with foam balls (of two different sizes) for varying depths of filling (no filling, one-third, two-third, and full). Accelerometers are mounted at different positions along the tube length and at the table to record the accelerations data for evaluation of damping ratio. From the recorded responses, frequency, mode shape and damping ratio of the fundamental mode are evaluated using a well-known approach. The damping ratio is noted to be around 1.41x (times) higher for the completely foam ball (bigger size) filled case under r.m.s base acceleration of 0.3 g when compared with the values corresponding to the empty case. The results suggest that the bigger foam balls enhance the damping ratio significantly without altering the natural frequency owing to additional energy dissipation in friction and impact generated through the sliding and collision of the balls while the tube is in motion.

Growth of a bubble cloud in CO2-saturated water under microgravity.

The diffusion-driven growth of a dense cloud of bubbles immersed in a gas-supersaturated liquid is a problem that finds applications in several modern technologies such as solvent-exchange micro-reactors, nanotechnology or the manufacturing of foamy materials. However, under Earth's gravity conditions, these dynamics can only be observed for a very limited time if the cloud is not attached to a surface, due to the action of buoyancy, i.e. of gravity effects. Here, we present experimental observations of the time evolution of dense bubble clouds growing in CO2-supersaturated water under microgravity conditions. We report the existence of three regimes where the bubble cloud exhibits different growth rates. At short times, each bubble grows independently following the Epstein-Plesset equation. Later on, bubbles start to interact with each other and their growth rate diminishes as they compete for the available CO2. When this happens, the growth rate slows down. This occurs earlier the deeper the bubble is in the cloud. Finally, at long times, only those bubbles on the husk continue growing. These regimes may be qualitatively described by a mathematical model where each individual bubble grows in the presence of a constellation of point mass sinks. Despite the model being only valid for dilute bubble clouds, its predictions are consistent with the experimental observations, even though the bubble clouds we observe are rather dense.

Effect of partial replacement of coarse aggregate by polystyrene balls on the shear behaviour of deep beams with web openings

Abstract Thirteen specimens were experimentally tested under single midspan concentrated loads to study the shear behavior of lightweight concrete (LWC) and normal weight concrete (NWC) deep beams with web openings. In this research, the term LWC refers to the concrete obtained by partially replacing aggregate by polystyrene foam balls not the concrete containing lightweight aggregate. This resulted in a weight reduction of LWC beams in this research by approximately 30% compared to NWC compartments. The studied variables were the dimensions and location of openings, transverse reinforcement ratio, and shear span to depth ratio (a/d). It was found that the overall shear behavior and failure mode for LWC deep beams are comparable to those of the NWC specimens. This is very promising and encouraging to build lighter deep beams of similar structural behaviour as that of NWC deep beams. Dimensions of the openings have a significant effect on the behaviour of failure and shear strength of LWC and NWC deep beams. It was found that increasing the depth of the opening from 20 % to 40 % of the beam depth led to a reduction in the ultimate load by up to 46.4 %. Finite element modelling of the test beams was carried out to verify numerical results versus experimental work and both were very well correlated. In addition, a parametric study was conducted to assess the effect of internal stiffening around openings in deep beams. The maximum enhancement in the shear capacity was approximately 30 % for beams, internally strengthened by additional reinforcement on the perimeter of openings compared to the beams without any reinforcement around the openings. Strut-and-Tie model (STM) was carried out as a rational approach to predict the shear behaviour of studied beams. It was found that STM underestimates the shear of the studied beams compared to experimental results for different tested beams but the agreement between both of them was acceptable. It is recommended that the depth of opening should not exceed 20 % of the depth of the deep beam and if the depth of opening is more than that or lies in the shear span it is highly recommended to strengthen the opening internally by additional reinforcement around its perimeter.