Search Results (18)

The design of patrol boats, especially in Indonesian waters with extreme sea conditions, requires good stability capabilities and self-righting moments. These conditions require patrol boats to have anti-capsized capabilities where, with these capabilities, the patrol boat can return to an upright position at extreme heeling angles. This study investigates how changing the center of gravity (CoG) due to the deckhouse height factor improves self-righting moment capabilities. Four different deckhouse heights are examined to find the optimal self-righting roll moment, with a deckhouse height in the 2.01–2.31 m range. In addition, the presence of the self-righting roll moment is also validated by the computational fluid dynamics (CFD) method using three different mesh sizes. The height of the deckhouse can significantly influence the ship’s stability. The initial investigation shows ships with minimum deckhouse heights of 2.06 m have positive righting lever arms at 170° and are classified as anti-capsized ships. It has been discovered that buoyancy and the center of gravity are crucial variables in obtaining the self-righting moment. The deckhouse’s height increases the stability of the ship’s righting arm by enhancing the metacenter point. The findings demonstrate that more excellent stability is achieved with a larger deckhouse height. Full article

This study addresses Roger Scruton’s understanding of what he called “moments of revelation”. In two short essays, both entitled “Effing the ineffable”, Scruton framed his discussion of moments of revelation with reference to the medieval Christian mystical discourse. Introducing the medieval discussion of this topic, this study provides an analysis of Scruton’s approach to the theme. In tune with the traditional discourse on revelation, his general aim was to demonstrate that there are ways of revealing important truths about the supernatural, of the world “beyond the window”, that do not require words to be pronounced. He calls our experiences of such phenomena moments of revelation and identifies four different transitory sources of revelation. This study deals with them one by one, after considering whether it is right to label such a revelation transcendental. The four sources of Scruton’s moments of revelation are natural beauty, the beauty of painting, the beauty of music, and personal encounters. The first three examples are connected to his thoughts on art and beauty as a substitute of divine revelation. Perhaps the most surprising of these is the last ones, moments of intersubjective human relationships, “our knowledge of each other”. Relying on both Buber and Levinas, Scruton makes the strong claim that it is in the other that we can experience that world “beyond the window”. His phenomenological exploration of human encounters sheds light on concepts like grace, shekhinah, or real presence and gift. He explains the Christian understanding of the human–divine relationship as well along the lines of the nature of interpersonal human relationship, both of them being in a certain sense, he claims, transcendental. From grace, his account moves forward to self-sacrifice and finally arrives at his idiosyncratic understanding of gratefulness for life. His moments of revelation in art and interpersonal exchange turn out to be, indeed, late and secular versions of the Christian understanding of revelation. In its summary, this study claims that revelation, understood by Scruton as a form of general human experience, allows to catch a glimpse of that which is beyond the window, by the direct, sensually based experience of either the existence of another person or of the beauty of nature and art. Full article

To address loess–mudstone tunnel damage resulting from mudstone swelling induced by water absorption in cold regions, model experiments and numerical simulations were employed to study the tunnel surrounding rock pressure distribution and the stress characteristics of support structures during mudstone swelling at the tunnel base. The findings reveal that the base uplift of the tunnel leads to a rapid stress increase on the arch, and the self-supporting of the interface is insufficient, causing uneven stress distribution on the tunnel. The stress peak value at the bottom of the outer arch is 30.8% of that at the inner side. The internal force of the tunnel lining at the arch crown is the largest. The compressive stress appears at the arch feet, while the tensile stress appears at the outer side of the lining. The bending moments of the inverted arch are larger than those of the arch shoulders and arch crown. The left arch shoulder and arch bottom are primarily subjected to negative bending moments, and the maximum values are about −500 kN·m and −400 kN·m, respectively. The left side of the inverted arch is first to crack, and two main cracks then appeared at the left and right arch shoulders, respectively. The formation and development of the longitudinal cracks in the arch induced by water absorption cause the inverted arch bulge failure. This study helps understand the damage mechanism of the loess–mudstone tunnel in cold regions. Full article

In this work, we further developed a new approach for modeling the processes of the self-assembly of complex molecular nanostructures using molecular dynamics methods; in particular, using a molecular dynamics manipulator. Previously, this approach was considered using the example of the self-assembly of a phenylalanine helical nanotube. Now, a new application of the algorithm has been developed for implementing a similar molecular dynamic self-assembly into helical structures of peptide nanotubes (PNTs) based on other peptide molecules—namely diphenylalanine (FF) molecules of different chirality L-FF and D-FF. In this work, helical nanotubes were assembled from linear sequences of FF molecules with these initially different chiralities. The chirality of the obtained nanotubes was calculated by various methods, including calculation by dipole moments. In addition, a statistical analysis of the results obtained was performed. A comparative analysis of the structures of nanotubes was also performed using the method of visual differential analysis. It was found that FF PNTs obtained by the MD self-assembly method form helical nanotubes of different chirality. The regimes that form nanotubes of right chirality D from initial L-FF dipeptides and nanotubes of left chirality L from D-FF dipeptides are revealed. This corresponds to the law of changing the sign of the chirality of molecular helical structures as the level of their hierarchical organization becomes more complicated. Full article

Drilling trajectory control technology for near-horizontal directional drilling in coal mines is mainly determined empirically by manual skew data, and the empirical results are only qualitative and variable, meanwhile possessing great instability and uncertainty. In order to improve the accuracy and efficiency of drilling trajectory prediction, this paper investigates a random forest regression-based drilling trajectory prediction method after applying numerous machine learning methods to experimental data for comparison. In the selection of prediction features, this paper replaces all feature variables of the borehole trajectory with feature values with higher cumulative influence weights, and screens out three variables with high importance, azimuth, inclination and bend at the present moment of the drill, as the input variables of the model, and the increments in the borehole in a horizontal direction, left and right direction, and up and down direction at the present moment and the next moment as the output variables of the model. In the model training, the model in this paper uses the bootstrap self-service method resampling technique to collect training sample data, constructs a random forest regression model, and takes the mean value of the decision tree output as the result of the borehole trajectory prediction. To further improve the model accuracy, the paper improves the prediction performance of the model by adjusting the parameters of the random forest model such as tree, depth, minimum sample of leaf nodes, minimum sample number of internal node division, etc. The model is also evaluated by using common machine learning evaluation metrics R2 score, RAE, RMSE and MSE. The experimental results show that the average absolute error of the model drops to 1% on the prediction of the horizontal direction and up and down direction; the average absolute error of the model drops to 9% on the prediction of the left and right direction, and this error rate reaches the error requirement in the actual construction process, so the model can effectively improve the prediction accuracy of borehole trajectory while improving the safety of directional construction. Full article

This study compared rheumatoid arthritis (RA) post-menopausal women with pathological involvement of the lower limb joints and age-matched post-menopausal women without RA regarding the dynamic joint stiffness (DJS) of knee during the stance phase of gait. Eighteen RA women and eighteen age-matched women were selected. Gait assessed through a three-dimensional motion analysis system synchronized with a force plate. Subjects walked barefoot at self-selected speed, and 14 valid trials were collected (comprising 7 left and 7 right foot-steps on force plate). The “moment of force—angle” plot of knee in sagittal plane was determined. The stance phase was split into three sub-phases: first knee flexion sub-phase (1st KFS); knee extension sub-phase (KES); second knee flexion sub-phase (2nd KFS). A linear model represented each sub-phase and DJS calculated by the slope. Model fitting was assessed through the coefficient of determination (R²). R² values for both groups were higher than 0.8 during 1st KFS and KES but not during 2nd KFS. RA women yielded a higher DJS value during 2nd KFS (p < 0.01). Concerning the other sub-phases, no differences were observed between groups. The findings suggested the splitting methodology used could be modelled by a linear “moment of force—angle” relationship, namely, during 1st KFS and KES. During 2nd KFS, RA women yielded a stiffer behavior. Full article

The patrol boat is one of the critical aspects for archipelago countries, such as Indonesia, to supervise and maintain the sea border. Due to rough sea conditions, the patrol boat could lose its stability due to the loss of a self-righting roll moment in severe waves. One of the most challenging aspects is to ensure the sufficient stability of the patrol boat during rough conditions. Another challenge is to design a boat that has a self-righting moment during rolling in extreme conditions. This paper examines the design of an anti-capsize ship by improving the self-righting moment with different deck houses height. The rough condition is described when the boat experiences a roll angle of 170°. The principal dimensions of the patrol boat, i.e., Lpp, B, H, T, are 13.0 m, 4.2 m, 2.19 m, and 1.15 m, respectively. Four different deck house heights are compared to obtain the best self-righting roll moment with a height increment of 0.1 m. The physical model is implemented with ship model 1:27.4. In addition, computational fluid dynamics (CFD) is also used to support the proof of the existence of the self-righting roll moment. It is revealed that the center of gravity and buoyancy are essential parameters to acquire the self-righting moment. The height of the deckhouse improves the center of the metacenter, which influences the righting arm of ship stability. The results show that our ship design has a self-righting moment during heel at 180°. Full article

New technologies for monitoring grip forces during hand and finger movements in non-standard task contexts have provided unprecedented functional insights into somatosensory cognition. Somatosensory cognition is the basis of our ability to manipulate and transform objects of the physical world and to grasp them with the right amount of force. In previous work, the wireless tracking of grip-force signals recorded from biosensors in the palm of the human hand has permitted us to unravel some of the functional synergies that underlie perceptual and motor learning under conditions of non-standard and essentially unreliable sensory input. This paper builds on this previous work and discusses further, functionally motivated, analyses of individual grip-force data in manual robot control. Grip forces were recorded from various loci in the dominant and non-dominant hands of individuals with wearable wireless sensor technology. Statistical analyses bring to the fore skill-specific temporal variations in thousands of grip forces of a complete novice and a highly proficient expert in manual robot control. A brain-inspired neural network model that uses the output metric of a self-organizing pap with unsupervised winner-take-all learning was run on the sensor output from both hands of each user. The neural network metric expresses the difference between an input representation and its model representation at any given moment in time and reliably captures the differences between novice and expert performance in terms of grip-force variability.Functionally motivated spatiotemporal analysis of individual average grip forces, computed for time windows of constant size in the output of a restricted amount of task-relevant sensors in the dominant (preferred) hand, reveal finger-specific synergies reflecting robotic task skill. The analyses lead the way towards grip-force monitoring in real time. This will permit tracking task skill evolution in trainees, or identify individual proficiency levels in human robot-interaction, which represents unprecedented challenges for perceptual and motor adaptation in environmental contexts of high sensory uncertainty. Cross-disciplinary insights from systems neuroscience and cognitive behavioral science, and the predictive modeling of operator skills using parsimonious Artificial Intelligence (AI), will contribute towards improving the outcome of new types of surgery, in particular the single-port approaches such as NOTES (Natural Orifice Transluminal Endoscopic Surgery) and SILS (Single-Incision Laparoscopic Surgery). Full article

Background and Objectives: Friable or infected tissue remains a challenge in surgical aortic valve replacement. We recently described the “Caput medusae” method, in which circumferential tourniquets temporarily secure the prosthesis and are then gently knotted. Tourniquets have been shown to develop significantly less force than knots. The current study investigates the critical threshold forces for tissue damage to the aortic annulus. Materials and Methods: In 14 fresh porcine hearts, the aortic valve leaflets were removed and several pledgeted sutures were placed along the annulus at defined locations. The hearts were mounted in a self-constructed device. Incremental traction force was applied to every suture and continuously recorded. The movement of each Teflon pledget was filmed with a high-speed camera. Forces at the moment of pledget “cut-in” as well as complete “tear-out” were determined from the recordings. Results: The average threshold force was determined 9.31 ± 6.04 N for cut-in and 20.41 ± 10.02 N for tear-out. Detailed analysis showed that the right coronary region had lower threshold forces than the other regions (4.77 ± 3.28 N (range, 1.67–12.75 N) vs. 10.67 ± 6.04 N (1.62–26.00 N) for cut-in and 10.67 ± 4.04 N (5.40–18.64 N) vs. 23.33 ± 9.42 N (9.22–51.23 N) for tear-out). The findings are discussed in conjunction with the knot and tourniquet forces from our previous study. Conclusions: Even in healthy tissue, moderate forces can reach a critical level at which a Teflon pledget will cut into the annulus, while a complete tear-out is unlikely. The right coronary portion is more susceptible to damage than the remaining regions. When compared to previous data, forces during manual knotting may exceed the critical cut-in level, while rubber tourniquets may provide a higher safety margin against tissue rupture. Full article

In this paper, we propose and use a new approach for a relatively simple technique for conducting MD simulation (MDS) of various molecular nanostructures, determining the trajectory of the MD run and forming the final structure using external force actions. A molecular dynamics manipulator (MD manipulator) is a controlled MDS type. As an example, the applicability of the developed algorithm for assembling peptide nanotubes (PNT) from linear phenylalanine (F or Phe) chains of different chirality is presented. The most adequate regimes for the formation of nanotubes of right chirality D from the initial L-F and nanotubes of left chirality L of their initial dipeptides D-F modes were determined. We use the method of a mixed (vector–scalar) product of the vectors of the sequence of dipole moments of phenylalanine molecules located along the nanotube helix to calculate the magnitude and sign of chirality of self-assembled helical phenylalanine nanotubes, which shows the validity of the proposed approach. As result, all data obtained correspond to the regularity of the chirality sign change of the molecular structures with a hierarchical complication of their organization. Full article

Background and Objectives: When performing the jump inside kick in Wushu, it is important to understand the rotation technique while in mid-air. This is because the score varies according to the mid-air rotation, and when landing after the mid-air rotation, it causes considerable injury to the knee. This study aimed to compare the differences in kinematic and kinetic variables between experienced and less experienced knee injuries in the Wushu players who perform 360°, 540°, and 720° jump inside kicks in self-taolu. Materials and Methods: The participants’ mean (SD) age was 26.12 (2.84) years old. All of them had suffered knee injuries and were all recovering and returning to training. The group was classified into a group with less than 20 months of injury experience (LESS IG, n = 6) and a group with more than 20 months of injury experience (MORE IG, n = 6). For kinematic measurements, jump inside kicks at three rotations were assessed by using high-speed cameras. For kinetic measurements, the contraction time and maximal displacement of tensiomyography were assessed in the vastus lateralis, vastus medialis, rectus femoris, biceps femoris, gastrocnemius lateralis, gastrocnemius medialis, and tibialis anterior. The peak torque, work per repetition, fatigue index, and total work of isokinetic moments were assessed using knee extension/flexion, ankle inversion/eversion, and ankle plantarflexion/dorsiflexion tests. Results: Although there was no difference at the low difficulty level (360°), there were significant differences at the higher difficulty levels (540° and 720°) between the LESS IG and the MORE IG. For distance and time, the LESS IG had a shorter jump distance, but a faster rotation time compared to those in the MORE IG. Due to the characteristics of the jump inside kick’s rotation to the left, the static and dynamic muscle contractility properties were mainly found to be higher in the left lower extremity than in the right lower extremity, and higher in the LESS IG than in the MORE IG. In addition, this study observed that the ankle plantarflexor in the LESS IG was significantly higher than that in the MORE IG. Conclusion: To become a world-class self-taolu athlete while avoiding knee injuries, it is necessary to develop the static and dynamic myofunctions of the lower extremities required for jumping. Moreover, it is considered desirable to train by focusing on the vertical height and the amount of rotation during jumping. Full article

Little is known about nutritional factors during weight loss on digital commercial weight loss programs. We examined how nutritional factors relate to weight loss for individuals after 4 and 18 months on a mobile commercial program with a food categorization system based on energy density (Noom). This is a two-part (retrospective and cross-sectional) cohort study. Two time points were used for analysis: 4 months and 18 months. For 4-month analyses, current Noom users who met inclusion criteria (n = 9880) were split into 5% or more body weight loss and stable weight loss (0 ± 1%) groups. Individuals who fell into one of these groups were analyzed at 4 months (n = 3261). For 18-month analyses, individuals from 4-month analyses who were still on Noom 18 months later were invited to take a one-time survey (n = 803). At 18 months 148 participants were analyzed. Noom has a system categorizing foods as low-, medium-, and high-energy-dense. Measures were self-reported proportions of low-, medium-, and high-energy-dense foods, and self-reported nutritional factors (fruit and vegetable intake, dietary quality, nutrition knowledge, and food choice). Nutritional factors were derived from validated survey measures, and food choice from a novel validated computerized task in which participants chose a food they would want to eat right now. ANOVAs compared participants with 5% or more body weight loss and participants with stable weight (0 ± 1%) at 4 months on energy density proportions. Analyses at 18 months compared nutritional factors across participants with >10% (high weight loss), 5–10% (moderate weight loss), and less than 5% body weight loss (low weight loss), and then assessed associations between nutritional factors and weight loss. Individuals with greater weight loss reported consuming higher proportions of low-energy-dense foods and lower proportions of high-energy-dense foods than individuals with less weight loss at 4 months and 18 months (all ps < 0.02). Individuals with greater weight loss had higher fruit and vegetable intake (p = 0.03), dietary quality (p = 0.02), nutrition knowledge (p < 0.001), and healthier food choice (p = 0.003) at 18 months. Only nutrition knowledge and food choice were associated with weight loss at 18 months (B = −19.44, 95% CI: −33.19 to −5.69, p = 0.006; B = −5.49, 95% CI: −8.87 to −2.11, p = 0.002, respectively). Our results highlight the potential influence of nutrition knowledge and food choice in weight loss on a self-managed commercial program. We also found for the first time that in-the-moment inclination towards food even when just depicted is associated with long-term weight loss. Full article

This article argues for the importance of collaboration as a species of literary relation in Henry James’s work. Collaboration was increasingly popular towards the end of the nineteenth century, and yet, James’s interest in and occasional practice of this compositional mode has been largely overlooked. This is partly due to James’s own ambivalent and contested relationship with multiple authorship, most obviously in his contribution to The Whole Family. However, James’s frequent identification of collaboration as a “mystery” indicates the extent to which it exerted a considerable influence over his imagination and thinking, and its association with some of his most formative moments of novelistic and vocational self-awareness. “Collaboration” is also a literary subject in its own right, most obviously in James’s 1892 story of that name, and the depiction of the practice as a unifying, if occasionally divisive, ideal offers a complex and often enigmatic vision of sociable reciprocity. Full article

Golf is a sport which requires players to use ground interaction to generate clubhead speed in order to propel the ball towards the target. Force platforms are a technology which can be used to measure these ground reaction forces. Golfers generate force through a combination of jumping, sliding or twisting actions during the swing. Understanding how golfers generate these forces and if there are any groups which golfers could be clustered into could be used to enhance golf instruction as well as clubhead design or fitting practices for golf equipment. A total of 105 right-handed experienced golfers (handicap mean = 8.32 ± 8.31) consented to participate in the study of different swing speeds (31 below 95 mph, 41 over 105 mph and 33 between 95 and 105 mph). A calibrated single force plate was used for the test which sampled at 1000 Hz and recorded force and moment data in three axes. After a self-guided warm up, the players were instructed to hit five 7-iron shots and five drives to the best of their ability in an indoor hitting bay which used a launch monitor to record the club delivery and ball flight information. It was found that handicap or swing speed did not dictate the primary force production mechanism (sliding, jumping or twisting/spinning). This knowledge could aid engineers to design equipment better suited to the individual and help coaches build individualized programs to create power and clubhead speed in all players. Full article

The autonomous floor-cleaning self-reconfigurable robots have entered into the practical stage by establishing enhanced area coverage over the fixed morphology counterparts. Energy consumption during the self-reconfiguration, i.e., changing the shape of the robot from one form to another, becomes a primary focus in these robots that carry finite energy sources. In this paper, hTetro platform with two hinge dissections namely, Left–Left–Left (LLL) and Left–Left–Right (LLR) are modeled and assessed for the energy consumption during the reconfiguration. The geometry of the two dissections, its workspaces, and the set of inverse kinematics solutions for the seven forms are presented. The inverse dynamics using the Newton–Euler approach was adopted to calculate the wrench, i.e., forces and moments at the hinge joints, and subsequently assess the power consumed during the reconfigurations of two hinge dissections in the simulation. Extensive experiments were performed across the two assembled platforms to estimate the power consumption by logging the current data. The comparison was made with the simulation results. The results are particularly useful in the selection of reconfiguration with minimal energy consumption during the floor cleaning. Full article