Adaptation Strategy In Attachment–Detachment Cycles When Faced With Changes In Incline And Orientation During Gecko Climbing

Background: Geckos are endowed with the extraordinary capacity to move quickly in various environments; they benefit from efficient control for the complex footpads. Research on the locomotor behavior and contact status in the attachment–detachment (A-D) cycle of the footpads for diverse challenges is linked to the revelation of regulatory strategy. At present, there is a lack of systematic research for the A-D cycle, which limits the understanding of the adhesive locomotion mechanism.Methods: The A-D cycle that facilitates the level and up–down locomotion on inclined and vertical surfaces of Gekko gecko was investigated to clarify the locomotion postures and durations in the release, swing, contact, and adhesion stages, respectively. This reveals the relationship between the structure and function of the attachment devices, and its regulation when faced with changing locomotion demands.Results: Despite changes in climbing demands, gecko foot locomotion posture (angle extremes and changing trends) in the swing stage, the posture (bending angle: fore 41°, hind 51°) and contact time ratio (7.42%) in the contact stage remain unchanged, which is in contrast with the adjustable postures in the stance phase. Furthermore, the variation range of the forefoot locomotion posture is larger than that of the hindfoot, and the forefoot angle changing trend is opposite to that of the hindfoot, indicating that the combination of anatomical structure and functional demands results in the differentiation in the adaptation mode of the A-D cycle for the fore- and hindfoot. Conclusions: Gecko’s fore- and hindfoot have evolved different structures to undertake differential functions. The function (adhesion) for various locomotion demands relates to footpad deployment in the stance phase but is unaffected by the regulations (postures and durations) in the swing and contact stages. The results demonstrate that the unified adaptation strategy reduces the diversity and complexity of the control. It advances the understanding of the adhesive locomotion mechanism, reflects the structural evolution and adaptation strategy of attachment devices for functional requirements and provides biological inspiration for effective design and control of adhesion robots.

NUMERICAL MODELING TO PRESSURE DROP OF TANGENTIAL SWIRLS

The results of the study of numerical simulation of the hydraulic resistance of a vortex contact stage by the finite element method using k-ε turbulence models are presented. The dependence for calculating the coefficient of hydraulic resistance is obtained.

Study of dust collection effectiveness in cyclonic-vortex action apparatus

The object of research is the efficiency of dust collection of fine dust in an apparatus with an intense turbulent mode of phase interaction. One of the most problematic areas of the existing dust and gas cleaning equipment is the low efficiency of collecting fine dust. Effective cleaning of exhaust gases from dust involves the use of multi-stage cleaning systems, including wet and dry dust cleaning devices, which entails high capital and operating costs. These disadvantages are eliminated in the developed design of the cyclone-vortex dust collector with two contact zones. The device implements both dry and wet dust collection mechanisms, which allows for high efficiency of dust removal at high productivity. The conducted studies of the total and fractional efficiency of dust collection when changing the operating parameters of the developed device showed that the efficiency of collecting fine dust is 98–99 %. The increase in the efficiency of dust collection in the dry stage of the device is due to an increase in centrifugal force. In the wet stage of contact, the efficiency reaches its maximum values due to the vortex crushing of the liquid in the nozzle zone of the apparatus. Studies of the fractional efficiency of the apparatus show that with an increase in the diameter of the captured particles, the efficiency of the dust collection process for dry and wet stages, as well as the overall efficiency, increases. With an increase in the density of irrigation, the overall efficiency of dust collection in the apparatus increases. It has been established that an increase in the efficiency of capturing highly dispersed particles occurs due to turbulent diffusion, the value of which is determined by the frequency of turbulent pulsations and the degree of entrainment of particles during the pulsating motion of packed bodies. To describe the results obtained, a centrifugal-inertial model for a dry contact stage and a turbulent-diffusion model of solid particle deposition for a wet contact stage are proposed, which make it possible to calculate the dust collection efficiency of the contact stages, as well as the overall efficiency of the cyclone-vortex apparatus. The results obtained show the prospects of using devices of this design at heat power plants and other industries.

Mechanism and situation of injuries in fast bowlers: A YouTube-based video analysis study

Objectives: The present study was conducted with the objective of identifying the cause of injuries in fast bowlers. Materials and Methods: The present study is a video analysis study, keywords such as “fast bowler’s injury,” “failure of bowling,” and “cricket injuries” were searched on YouTube. Bowling action was divided into four stages – Stage 1 – jump, Stage 2 – back foot contact, Stage 3 – front foot contact, and Stage 4 – follow-through. The type and timing of injury (stage) were noted after analyzing the videos. Results: Sixteen injuries were identified in five videos. It was observed that 15 athletes had acute injury to lower limb and 1 athlete had an acute injury to lower back. 13/16 injuries happened in Stage 2 and 3/16 injuries happened in Stage 4. Conclusion: Most of the injuries happened at the time of landing and follow-through. Therefore, improvement of ground conditions, especially around the bowling area, and addition of exercise-based injury prevention programs can reduce the risk of injuries. This is more important for young fast bowlers at the club levels and state levels, as proper training at an early stage, can prevent injuries in many young fast bowlers.

Surface evolution of Janus Cu-Ag nanoparticles: Influence of atom arrangements and interface structures

In this paper, the effect of the atom ratio and interface structure on the surface evolution of Janus Cu–Ag Nanoparticles (NPs) were studied by molecular dynamics (MDs) simulation during sintering process. The results show that Cu/Ag alloys tend to form the Cu-core@Ag-shell NPs with stable configuration in the case of excessive Ag. However, the different arrangements of atoms and interface lead to Janus Cu–Ag NPs exhibiting unique coalescence during the contact stage of sintering process, and the interface with Cu/Ag two-type atoms is more likely to diffuse. Moreover, the systems gradually change from separate NPs to a uniform Cu/Ag alloy as the temperature rising, meanwhile the shrinkage ratio of the Janus Cu–Ag NPs is stable at 80%.

Investigation on the mass transferring near-contact binary TT Cet

First multi-colour complete light curves and low-resolution spectra of short-period eclipsing binary TT Cet are presented. The stellar atmospheric parameters of the primary star were derived through spectra fitting as: $T_{eff}=7\,091\pm124\,{\text{K}}$ , $\log g = 4.15\pm0.33\,{\text{cm}}/\text{s}^2$ , and $[Fe/H]=-0.23\pm0.04\,\text{dex}$ . The light curves were analysed using the Wilson–Devinney code. The photometric solution suggests that this target should be a near-contact binary with the primary component filling its critical Roche lobe (i.e. SD1-type NCB). The luminosity enhancement around the primary light maximum (phase 0.10–0.40) on the light curve was detected like other SD1-type NCBs, which could be caused by a hot spot near the facing surface of the secondary component due to mass transfer. Long-term decrease of the orbital period at a rate of $dP/dt=-5.01\,({\pm}0.06)\times 10^{-8}\,{{\text{d}} \cdot{yr}}^{-1}$ was detected by the O–C analysis, which supports the mass transfer from the primary to the secondary and is consistent with its primary filling configuration. No third body was found through the light curve and O–C analysis. TT Cet may locate in the broken contact stage predicted by the thermal relaxation oscillation theory (TRO) and will evolve to the contact stage eventually. It is another good observational example supporting the TRO theory. We have collected all known SD1-type NCBs with absolute parameters from the literatures. The relations of these parameters are summarised for these rare systems.

Desain Pembelajaran Berbasis Literasi Sains dan Berwawasan Kemaritiman sebagai Hasil Pelatihan di SMAN 4 Tanjungpinang

Learning designing becomes an important part of the process to achieve learning objectives. Likewise, when teachers enhancestudents’ scientific literacy, the efforts must also be made from the learning design. The design of learning based on scientific literacy becomes very important when the orientation of science learning is not just to achieve cognitive aspects, but even more to the students' ability to apply science and have the attitude and ability to make decisions related to science in their lives. One important aspect in the design of learning based on scientific literacy is the relevance of the context of science to concepts or knowledge. For students inKepulauan Riau, the maritime context is very relevant to be discussed in the body of science. Through intensive training at SMA Negeri 4 Tanjungpinang, biology and chemistry teachers were trained to design science literacy-based learning and maritime-based contexts. The learning design developed refers to the STL (science and technology literacy) approach which has 5 stages of learning, namely the contact stage, the elaboration stage (content), the curriculum stage, decision making, and the nexus stage. From the results of the mentoring by the training facilitator, 2 learning designs were produced (biology and chemistry subjects). The maritime context is integrated in the material Biodiversity (for Biology) and Petroleum (for Chemistry).

Scientific Literacy-Based Chemical Teaching Materials Design of Chemical Solution Materials on Sea Pollution Context

The science teaching materials needed today are teaching materials that can make students literate in science. One way is to develop teaching materials based on scientific literacy. To produce good teaching materials, certain designs are needed to achieve learning goals and can improve students' scientific literacy. Students who have studied chemistry should be able to analyze natural phenomena in scientific chemistry, one of which is marine pollution. This research was conducted to design high school chemistry teaching materials in connecting the context of sea pollution with chemical solution material. The method of this research is descriptive qualitative which refers to the Model of Educational Reconstruction (MER). The instruments used were standard competencevalidation sheets, text analysis sheets, and teaching material validation sheets. The results showed: a) The results of the indicator standard competencevalidation and learning objectives cognitive and attitude aspects, the results of text analysis and the results of the validation of teaching materials, all obtained valid categories, with the average value of each CVI was 0.91; 0.93; 0.94; and 0.95, b) The design of teaching materials include the contact stage, the curriculum stage, the elaboration stage, the decision-making stage, and the Nexus stage. Keywords:Design of teaching materials; scientific literacy; sea pollution; chemical solution

Stress Analysis and Microstructure Evolution of Titanium Alloy Pipe during Flattening Processing

TA24 titanium alloy pipe with 638mm diameter and 19mm wall thickness is carried out continuous load flatten test, and the stress of internal and external pipe wall during flatten process is studied in this paper. The results show that the TA24 titanium alloy tube has good flattening performance, and the flattening process has experienced original stage, flattened oblate stage, flattened straight wall stage, flattened depressed stage, flattened concave contact stage. During the flattening process, the outer layer of the upper and lower wall of the tube is subjected to compressive stress, and the inner layer material is subjected to tensile stress. The tensile and compressive forces cause the vertical part of the upper and lower walls to be concave. The outer layer of the left and right circular arc parts is subjected to tensile stress and the inner layer is subjected to tensile stress. The compressive stress also causes the radius of the arc to decrease due to the combined force of the tensile and compressive forces, that is, the flattening occurs. With the decrease of and pressing distance under continuous loading condition, the metal on the left and right sides of the pipe gathers toward the middle depression, which aggravates the deformation of the upper and lower walls until the upper and lower walls contact, and the arc radius of the left and right walls decreases until the outer surface cracks. The pipe microstructure changes significantly into elongated deformation structure during the flattening process. The most severe part of the deformation is the left and right end arc of the pipe, followed by the upper and lower end depression.

Efficiency of cooling the water droplets within Jet-Film unit of cooling tower filler

Researches of blocks of sprinklers of cooling towers with jet-film devices are presented. The conducted numerical studies allow us to estimate the influence of the design and operating parameters of the proposed contact device on the efficiency of the process of cooling the recycled water. The increase in the average gas velocity leads to a more intense flow of water drops and more efficient cooling. To achieve high performance, it is necessary to create zones of drip interaction of phases with droplet sizes up to 100 µm at relatively low speeds of two-phase gas-liquid flow. Under such conditions, the drop can be cooled by more than 10°C within one contact stage. The proposed sprinkler units with jet-film contact devices will be able to achieve a lower level of cooling water temperatures in the cooling towers of industrial enterprises at relatively low operating costs.