Four propellers submarine drone modelling in a real environment

<span lang="EN-US">In order to reduce the hydrodynamic dampers and mechanical elements as rudders, we have in our previous publications proposed our architectural solution of an ROV with only four thrusters without rudders or diving bars. In the results we have justified the choice of the arrangement of the thrusters. Also, we have started the kinematic and dynamic studies of the marine robot and we have especially demonstrated by using the mathematical model under MATLAB in the last publication, that this ROV can move in a perfect environment without gravity or hydrodynamic dampers. In this article, we will study the behavior of this marine vehicle in a real environment with gravity and hydrodynamic dampers and we will view if this architectural solution can really allow the ROV to move and execute the given directional instructions.</span>

Fault diagnosis with states estimation in PV systems

The photovoltaic systems are electrical, electronic, and mechanical elements. These systems also face different environmental and operating conditions susceptible to failure. In addition, photovoltaic systems can be the only source of electricity generation, and an affectation on the energy supply can harm the community. In many places, photovoltaic systems are the only source of energy because they are not part of what is known in Colombia as the National Interconnected System (SIN). Which comprises the direct connection between large generators (hydroelectric and/or thermal plants) and consumers. In fact, PV system damage would affect food refrigeration or everyday things like charging a cell phone. Therefore, it is necessary to register, monitor the operation elements of PV systems, and develop strategies that allow the diagnosis to detect faults. In this work, we propose a fault-diagnosis using the PV systems measurements that is, power converter, photovoltaic panels with also mathematical models to determine the deviation between the estimated and measured signals as voltages and currents.

Wireless Manipulation Mechanism and Analysis for Actively Assistive Pinch Movements

Pinching motions are important for holding and retaining objects with precision. Therefore, training exercises for the thumb and index finger are extremely important in the field of hand rehabilitation. Considering the need for training convenience, we developed a device and a driving system to assist pinching motions actively via a lightweight, simple, and wireless mechanism driven by the magnetic forces and torques generated by magnets attached to the tip of these two fingers. This device provides accurate pinching motions through the linking structures connecting the two magnets. The fabricated device has minimal mechanical elements with an ultralightweight of 57.2 g. The magnetic field, the intensity of which is based on the time variant, generates a pinching motion between the thumb and index finger, thus rendering it possible to achieve repetitive training. To verify the generation of an active pinching motion, we fabricated a finger model using a 3D printer and a rubber sheet and observed the active motions generated by the newly developed device. We also verified the performance of the proposed mechanism and driving method via various experiments and magnetic simulations. The proposed mechanism represents an important breakthrough for patients requiring hand rehabilitation and wearable assistive motion devices.

Porous Gas Journal Bearings: An Exact Solution Revisited and Force Coefficients for Stable Rotordynamic Performance

Having come of age, gas film bearings enable high-speed oil-free (micro) rotating machinery with gains in efficiency and reliability, longer maintenance intervals, and a reduction in contaminants released to the atmosphere. Among gas bearing types, porous surface gas bearings (PGBs) have proven successful for 50+ years and presently are off-the-shelf mechanical elements. This paper reviews the literature on PGBs since the 1970s and reproduces an exact solution for the performance of cylindrical PGBs. Both the analytical model and an accompanying finite-element (FE) model predict the performance for two PGBs, a commercially available 76 mm diameter bearing and a smaller 25 mm diameter laboratory unit whose experimental performance is available. As expected, the FE model results reproduce the analytical predictions obtained in a minuscule computing time. For a set external supply pressure, as the radial clearance increases, the flow rate through the bearing grows until reaching a peak magnitude. The PGB load capacity is a fraction of the product of the set pressure difference (pS − pa) and the bearing projected area with a significantly large centering static stiffness evolving over a narrow region of clearances. Operation with shaft speed enhances the bearing load capacity; however, at sufficiently high speeds, significant magnitude cross-coupled forces limit the stable operation of a PGB. At constant operating shaft speed, as the whirl frequency grows, the bearing effective stiffness (Keff) increases, while the effective damping (Ceff) becomes positive for whirl frequencies greater than 50% shaft speed. Similar to a plain hydrodynamic journal bearing, the PGB is prone to a half-frequency whirl, albeit the system natural frequency can be high, mainly depending on the external supply pressure. In essence, for the cases considered, PGBs are linear mechanical elements whose load capacity is proportional to the journal eccentricity.

Analysis of the selection of chosen technical parameters of the powertrain system for a diesel-electric rail-road tractor

The article presents the results of a simplified analysis of the feasibility of designing a rail chassis of a two-way tractor with an internal combustion or electric drive. Basic traction and operating parameters have been assumed for which the road-rail tractor could operate in an effective manner. On their basis, strength calculations were carried out and mechanical elements of the drive system meeting the required assumptions were selected. All the calculations presented in the text were fulfilled. The technical feasibility of building the mechanical part of the rail running gear of a rail-road tractor driven by an internal combustion engine or electric motors has been demonstrated.

Anisotropic expansion of hepatocyte lumina enforced by apical bulkheads

Lumen morphogenesis results from the interplay between molecular pathways and mechanical forces. In several organs, epithelial cells share their apical surfaces to form a tubular lumen. In the liver, however, hepatocytes share the apical surface only between adjacent cells and form narrow lumina that grow anisotropically, generating a 3D network of bile canaliculi (BC). Here, by studying lumenogenesis in differentiating mouse hepatoblasts in vitro, we discovered that adjacent hepatocytes assemble a pattern of specific extensions of the apical membrane traversing the lumen and ensuring its anisotropic expansion. These previously unrecognized structures form a pattern, reminiscent of the bulkheads of boats, also present in the developing and adult liver. Silencing of Rab35 resulted in loss of apical bulkheads and lumen anisotropy, leading to cyst formation. Strikingly, we could reengineer hepatocyte polarity in embryonic liver tissue, converting BC into epithelial tubes. Our results suggest that apical bulkheads are cell-intrinsic anisotropic mechanical elements that determine the elongation of BC during liver tissue morphogenesis.

Wall thickness determination study for a plastic injection barrell due to the internal pressure

The use of Plastics is a very common activity nowadays, there are many different types of Injection Machines varying in size, the capacity of the material to inject, one of the main machines classifications is due to the injection pressure. One of the things to consider when the designing process is carried out is the factor of safety, this factor helps designers to avoid possible failures in mechanical elements of mechanisms, it provides a safety margin that aims to protect against any unexpected incident. The advantage of Simulation is that allows us to predict the behavior of elements under stress. In the Injection Process, barrels are elements subject to high pressure. This encourages analyzing wall thickness to find a suitable barrel wall thickness. The present study is focused on the design of the wall thickness, seeking reduce machining time that are required when producing the barrels that may be needed and to select the proper commercial barrel size reducing material waste.

Optimal Muscular Arrangement Using Genetic Algorithm for Musculoskeletal Potential Method with Muscle Viscosity

Muscle contractions (or equivalent mechanical elements) are responsible for joint movement in systems with musculoskeletal structure. Because muscles can only transmit force in the tensile direction in such systems, the internal force exists between the muscles. By utilizing the potential field generated by the internal force, the musculoskeletal potential method makes it possible to control the position without complex real-time calculations or sensory feedback by entering step-inputs of the balanced internal force at the target posture. However, the conditions of convergence to the target posture strongly depend on muscular arrangement. Previous studies have elucidated the mathematical conditions of the muscular arrangement; however, they provide sufficient conditions that must be satisfied by the muscular arrangement to converge to the target posture, which do not necessarily lead to optimal muscular arrangement conditions. This study proposes a method to determine the optimal muscular arrangement of a two-joint six-muscle system, wherein muscle viscosity is considered, that uses a genetic algorithm and an evaluation function considering the motion response time. The effect of the obtained muscular arrangement is verified in a simulation.

Tahap Minat dan Penerimaan Pelajar Terhadap Gamifikasi dalam Bidang Sirah

The gamification method is one of the 21st century teaching methods that combines learning content with mechanical elements of a game. Nowadays, this method is widely used by teachers while teaching online by using various free applications on the internet such as Kahoot!, Quizizz, Quizlet, Wordwall, and Qimkit. This study aims to identify the level of interest and acceptance of students on gamification methods in teaching and facilitation (PdPc) Islamic History. Quantitative research methods were used on 118 years four students in a primary school. Respondents were selected by simple random sampling. The results of the study showed that the level of interest and acceptance of primary school students towards gamification method in Sirah teaching is at a high level. It’s means that the level of interest and acceptance of students on gamification methods during PdPc is positive in that primary school. Implications of this study is to provide guidance for teachers in preparing and providing appropriate learning for the 21st century generations. Keyword: Interest, Student acceptance, Gamification, Islamic History and 21st century Education Abstrak Kaedah gamifikasi merupakan salah satu kaedah pengajaran abad ke-21 yang menggabungkan antara isi kandungan pembelajaran dengan unsur-unsur mekanik permainan. Kini, kaedah ini banyak digunakan oleh guru-guru semasa mengajar secara atas talian dengan menggunakan pelbagai aplikasi percuma di internet seperti Kahoot!, Quizizz, Quizlet, Wordwall, dan Qimkit. Kajian ini bertujuan untuk mengenal pasti tahap minat dan penerimaan pelajar terhadap penggunaan kaedah gamifikasi dalam pengajaran dan pemudahcaraan (PdPc) Sirah Pendidikan Islam. Kaedah penyelidikan kuantitatif telah digunakan terhadap 118 orang pelajar tahun empat di sebuah sekolah rendah. Responden dipilih dengan persampelan rawak mudah bertujuan. Hasil kajian mendapati tahap minat dan penerimaan pelajar sekolah rendah terhadap penggunaan kaedah gamifikasi dalam PdPc Sirah berada pada tahap tinggi. Ini menunjukkan bahawa penggunaan kaedah gamifikasi semasa PdPc adalah positif di sekolah rendah tersebut. Implikasi kajian ini dapat memberi petunjuk kepada guru-guru dalam penyediaan pembelajaran yang sesuai kepada generasi abad ke-21. Kata kunci: Minat, Penerimaan pelajar, Gamifikasi, Sirah dan Pendidikan abad ke-21

Early Stoic Determinism

This chapter pursues the question how teleological elements and efficient causation were merged in early Stoic cosmology. Stoic determinism is originally introduced in teleological terms, built on a distinction between a global and an inner-worldly perspective on events, in which Nature is the global active principle that determines all inner-worldly events. Additionally, Chrysippus’ efficient causality connects inner-worldly causes and their effects and is used to construct a contemporary-style universal causal determinism. The teleological and seemingly mechanical elements are combined in the early Stoic concept of fate (heimarmenē). The Stoics present details of this combination in biological and psychological analogies. It emerges that the early Stoic theories of Nature as world seed and world soul and world agent offer a fascinating solution to the question how science and theology, in particular predetermination, can be joined consistently within cosmology: theological and scientific explanation of the world are two complementary explanations of the same thing.