Morphological Control of Cilia-Inspired Asymmetric Movements Using Nonlinear Soft Inflatable Actuators

Soft robotic systems typically follow conventional control schemes, where actuators are supplied with dedicated inputs that are regulated through software. However, in recent years an alternative trend is being explored, where the control architecture can be simplified by harnessing the passive mechanical characteristics of the soft robotic system. This approach is named “morphological control”, and it can be used to decrease the number of components (tubing, valves and regulators) required by the controller. In this paper, we demonstrate morphological control of bio-inspired asymmetric motions for systems of soft bending actuators that are interconnected with passive flow restrictors. We introduce bending actuators consisting out of a cylindrical latex balloon in a flexible PVC shell. By tuning the radii of the tube and the shell, we obtain a nonlinear relation between internal pressure and volume in the actuator with a peak and valley in pressure. Because of the nonlinear characteristics of the actuators, they can be assembled in a system with a single pressure input where they bend in a discrete, preprogrammed sequence. We design and analyze two such systems inspired by the asymmetric movements of biological cilia. The first replicates the swept area of individual cilia, having a different forward and backward stroke, and the second generates a travelling wave across an array of cilia.

Pola Sebaran Teripang di Perairan Desa Penaga dan Desa Berakit Kabupaten Bintan

Tujuan penelitian adalah mengetahui kepadatan, pola sebaran dan struktur komunitas teripang di Perairan Desa Penaga Dan Desa Berakit Kabupaten Bintan Kepulauan Riau. Penelitian ini menggunakan metode Purposive Sampling. Penenentuan area dengan metode Belt Transect dan penangkapan menggunakan metode Swept Area. Hasil penelitian menunjukkan bahwa Teripang yang ditemukan diperairan Desa Penaga dan berakit terdapat 7 jenis yaitu H.impatiens, H.vagabunda, H. scabra, A.miliaris, H.atra, H.coluber, Phyllophorus sp. Kepadatan jenis tertinggi di perairan Desa Penaga berada pada spesies Phyllophorus sp. dengan nilai kepadan yakni 714 ind/ha sedangkan pada perairan Desa Berakit H.coluber dengan nilai kepadan yakni 647 ind/ha. Kondisis perairan di Desa Penaga dan Desa Berakit masih memenuhi baku mutu sehingga mendukung kehidupan Teripang. Nilai indeks Keanekaragaman pada Desa Penaga diperoleh nilai 0.99, sedangkan di Desa Berakit indeks keanekaragaman diperoleh nilai 1.57. Keseragaman Teripang di perairan Desa Penaga diperoleh nilai 0.71 dan Desa Berakit diperoleh nilai 0.97. Dominansi Desa Penaga diperoleh nilai 0.299 dan Desa Berakit diperoleh nilai 0.218. menunjukkan tidak ada spesies yang mendominansi. pola sebaran Desa Penaga dengan nilai 1.714 dan Desa Berakit dengan nilai 1.145, kedua lokasi memiliki pola sebaran mengelompok.

Optimum Solidity on Downwind Thai Sail Windmill

Solidity was a significant parameter affecting the efficiency of wind turbines. It is defined as the ratio between the projected area of all blades and the swept area of the rotor. The solidity could be improved by modifying the shape, cord length, or the number of blades. Research studies mentioned that higher solidity seemed to provide more power due to more blade area. However, it can be argued that if the solidity was too high, it would cause the airflow to be more obstructed and disrupted, causing the gained power to drop down instead. Thus, the optimum solidity, which made the wind turbines maximum effective, must be existent in itself and must be in the range between 0 - 100 %. Thai sail windmill is a kind of horizontal axis wind turbine currently used to pump seawater in salt farms in Thailand, where the general solidity is in the quite wide range of about 15 - 60 %. Mostly, the Thai sail windmill was designed by a rule of thumb. Hence, it has quite a low efficiency, which is only about 10 %. This study aims to investigate the optimum solidity of Thai sail windmill in the downwind type to enhance efficiency. The 4-blade and 6-blade rotors of 1-m radii were used as the prototypes for experiments using the tow testing method. The results showed that the optimum solidity of 4-blade and 6-blade rotors was 28 %, respectively, whereby the maximum efficiency of the 2 rotors was 17 and 25 %.

Wind Turbine Power Calculations Using MATLAB-SIMULINK

In this paper modeling and simulation has been studied by means of impact of energy generated by using wind turbine. The strength conversion primarily depends on the wind velocity and swept area. When design wind structures it’s very important to recognize predicted electricity and electricity output for calculating financial viability. Wind turbine performance depends on wind speed, air density, air pressure, temperature and length of blade. The modeling and simulation method is used to analyze the overall performance of wind turbine.

Insights into Enhanced Oil Recovery by Polymer-Viscosity Reducing Surfactant Combination Flooding in Conventional Heavy Oil Reservoir

Polymer flooding has a significant potential to enhance oil recovery in a light oil reservoir. However, for polymer flooding in a conventional heavy oil reservoir, due to unfavorable mobility ratio between water and oil, the improvement of sweep efficiency is limited, resulting in a low incremental oil recovery and failure to achieve high-efficiency development for polymer flooding in a conventional heavy oil reservoir. Inspired by the EOR mechanisms of the surfactant-polymer (SP) flooding process, the polymer-viscosity reducing surfactant flooding (P-VRSF) system was proposed to enhance conventional heavy oil recovery. Thus, to gain an insight into enhancing oil recovery by P-VRSF in a conventional heavy oil reservoir, the viscosity property, oil-water interfacial tension property, and oil viscosity reduction property were investigated. A series of parallel sand pack experiments were conducted to investigate enhanced oil recovery ability of polymer flooding and P-VRSF in a heterogeneous reservoir. Then, the 2D micromodel flooding experiments were conducted to investigate the EOR mechanism from porous media to pore level. Results demonstrated that polymer could increase the viscosity of injection water and improve the sweep efficiency. The emulsifying stability of surfactant with ultralow IFT (10-3 mN/m) was worse than that of the surfactant with higher IFT (10-2 mN/m). The viscosity reduction rate of the surfactant with higher IFT was higher than 80% at different oil-water volume ratios. The incremental oi recovery of P-VRSF was higher than that of polymer flooding. Moreover, the polymer-viscosity reducing surfactant with higher IFT could have higher incremental oil recovery. The 2D micromodel flooding results showed that the swept area of polymer flooding and P-VRSF was larger than that of water flooding. Moreover, the swept area of the surfactant with good emulsifying stability was larger than that of the surfactant with ultralow IFT. These findings could provide insights into enhancing oil recovery by P-VRSF in the conventional heavy oil reservoir.

Keanekaragaman Larva Ikan di Sekitar Muara Sungai Musi, Sumatra Selatan

Abstrak Estuari adalah salah satu habitat penting bagi ikan, namun terancam akibat peningkatan aktivitas manusia. Hal tersebut dapat memengaruhi keanekaragaman ikan di sekitarnya. Tujuan penelitian ini untuk menganalisis keanekaragaman dan kelimpahan larva ikan di sekitar muara Sungai Musi Sumatra Selatan. Penelitian ini menggunakan metode survei dengan cruise track design dan lintasan survei continuous parallel pada setiap stasiun secara swept area. Hasil penelitian menunjukkan bahwa indeks keanekaragaman (H’) di muara Sungai Musi pada Maret 2019 sebesar 0,639 sedangkan pada Mei 2019 sebesar 1,253. Kelimpahan relatif pada Maret 2019 lebih tinggi daripada Mei 2019. Kelimpahan Relatif (Kr) pada Maret 2019 antara 0,69–84,61% dan pada Mei 2019 antara 0,21–58,77%. Kelimpahan larva ikan yang ditemukan pada Mei lebih tinggi, yaitu sebanyak 456 individu dari 10 famili. Pada Maret ditemukan lebih rendah, yaitu sebanyak 143 individu dari 6 famili. Ditemukan larva ikan dari famili Engraulidae, Belonidae, Osphronemidae, Nemipteridae, Gerreidae, dan Gobiidae pada Maret. Sedangkan pada Mei 2019, yaitu Nemipteridae, Engraulidae, Scatophagidae, Chandidae, Lobotidae, Terapoinidae, Belonidae, Osphronemidae, Chanidae, Clupeidae. Abstract Estuary is one of important habitat for fish, yet is threatened by an increase in human activities. Thus affecting the diversity of fish around it. This study aim to determine the diversity and abundance of fish larvae around the mouth of Musi River in South Sumatra. This study was conducted using survey method with Cruise Track Design and continuous parallel survey track by swept area at each station. The results showed that the diversity index (H ') at the mouth of the Musi River in March 2019 was 0.639 while in May 2019 was 1.253. Relative Abundance (Kr) in March 2019 between 0.69–84.61% and in May 2019 between 0.21–58.77%. Abundance of fish larvae in May was found higher at 456 individuals from 10 families. Whereas in March it was found to be lower as many as 143 individuals from 6 families. The relative abundance in March 2019 was lower than in May. Fish larvae from the Engraulidae, Belonidae, Osphronemidae, Nemipteridae, Gerreidae and Gobiidae families were found in March. Whereas in May 2019 were Nemipteridae, Engraulidae, Scatophagidae, Chandidae, Lobotidae, Terapoinidae, Belonidae, Osphronemidae, Chanidae, Clupeidae.

Doppler Lidar Investigations of Wind Turbine Near-Wakes and LES Modeling with New Porous Disc Approach

Many bottom-mounted offshore wind farms are currently planned for the coastal areas of Japan, in which wind speeds of 6.0–10.0 m/s are extremely common. The impact of such wind speeds is very relevant for the realization of bottom-mounted offshore wind farms. In evaluating the feasibility of these wind farms, therefore, strict evaluation at wind speeds of 6.0–10.0 m/s is important. In the present study, the airflow characteristics of 2 MW-class downwind wind turbine wake flows were first investigated using a vertically profiling remote sensing wind measurement device (lidar). The wind turbines used in this study are installed at the point where the sea is just in front of the wind turbines. A ground-based continuous-wave (CW) conically scanning wind lidar system (“ZephIR ZX300”) was used. Focusing on the wind turbine near-wakes, the detailed behaviors were considered. We found that the influence of the wind turbine wake, that is, the wake loss (wind velocity deficit), is extremely large in the wind speed range of 6.0–10.0 m/s, and that the wake loss was almost constant at such wind speeds (6.0–10.0 m/s). It was additionally shown that these results correspond to the distribution of the thrust coefficient of the wind turbine. We proposed a computational fluid dynamics (CFD) porous disk (PD) wake model as an intermediate method between engineering wake models and CFD wake models. Based on the above observations, the wind speed range for reproducing the behavior of the wind turbine wakes with the CFD PD wake model we developed was set to 6.0–10.0 m/s. Targeting the vertical wind speed distribution in the near-wake region acquired in the “ZephIR ZX300”, we tuned the parameters of the CFD PD wake model (CRC = 2.5). We found that in practice, when evaluating the mean wind velocity deficit due to wind turbine wakes, applying the CFD PD wake model in the wind turbine swept area was very effective. That is, the CFD PD wake model can reproduce the mean average wind speed distribution in the wind turbine swept area.

Production and Biomass of Pokea Clam (Batissa violacea var. celebensis von Martens, 1897) in the Langkumbe River Waters North Buton Southeast Sulawesi

Langkumbe River is located in West Kulisusu District and has long been used by the community for various daily activities. One of the resources often used by the people around Langkumbe River is pokea clams. The aim of this study was to determine the production and biomass of pokea clams (B. violacea) in Langkumbe River Waters of North Buton Regency from August to October 2017. The sampling method used was swept area method using a traditional fishing gear "Tangge" (fishing gear). The samples were measured for the length, width and thickness. The total weight was measured with the clam/total mass (MT) and the weight of the meat. The samples were dried using an oven for 24 hours at 70 °C to obtain the shell-free dry mass (SFDW). Data were analyzed using standard formulas. The total sample obtained was 1.307 individuals. The highest density of pokea clam was found in August at 596.8 ind/m². Annual production of pokea clam (B. violacea) in Langkumbe River with a total annual production of 1,107.33 gSFDW/m2/year. The highest and lowest production are 297.09 gSFDW/m²/year at size 2.19-2.54cm and -0.16 gSFDW /m²/year at size 4.70-5.05cm, respectively. The total population biomass was 528.03 gSFDW/m2 with the highest biomass 171.72 gSFDW/m²/year at size 2.55-2.90 cm and the lowest was 1.40 gSFDW /m²/year at size 4.70-5.05 cm, so that the recovery rate (P/B ratio) was 2.1 gSFDW/m2/year.

Correction to: Comparison of biomass estimates from multiple stratification approaches in a swept area method for Pacific saury Cololabis saira in the western North Pacific

A correction to this paper has been published: https://doi.org/10.1007/s12562-021-01506-9