Magnitude Angle Research Articles

Performance of high-rise pile group adjacent slope

For the consideration of required elevation, pile shafts are partially buried in the soil stratum and partially exposed above the ground surface, known as high-rise pile group (HRPG). The HRPG is extensively used in the construction of infrastructures and is usually adjacent the slope. It is frequently subjected to high lateral loads from the superstructure, leading to considerable displacement and bending moment. To alleviate the deformation and internal force of HRPG, a batter pile is employed, forming the high-rise batter pile group (HRBPG). A numerical simulation is conducted to observe the response of HRPG foundation subjected to downwards lateral load adjacent slope. The effects of slope angle, cap elevation, and lateral loading magnitude are determined. Results of HRBPG are compared with traditional high-rise vertical pile group (HRVPG). Conclusions can be drawn as follows. (1) The slope has significant effect on the displacement and bending moment of HRPG, so it should be considered in the design process. The displacement and bending moment of pile shaft increase gradually with the slope angle (0°–30°) and then they have a sharp growth (45°–60°). (2) With the rise of cap elevation, the displacement increases dramatically, whereas the bending moment rises and then falls. The displacement is highly sensitive under lateral loading with a high cap elevation; the higher the elevation is, the greater the displacement will be. Special attention should be paid when a high pile cap is adopted under large lateral loading. The displacement and bending moment of HRBPG are considerably smaller than those of HRVPG at a high pile cap elevation. (3) The displacement and bending moment are relatively small when a diminutive lateral loading is performed; however, they have a sharp growth under large lateral loading. The larger the load is, the greater the bending moment and displacement will be. (4) The displacement of the leading pile is slightly larger than that of the trailing pile, whereas the bending moment of the rear pile is larger than that of the leading pile. The pile shaft displacement above the ground surface is considerably larger than that below. The maximum bending moment occurs at the pile head, and the pile toe has minuscule bending moment. (5) The use of batter pile is beneficial for reducing the displacement and bending moment, whereas the slope and lateral loading are detrimental.

Composite Guidance for Impact Time Control Under Physical Constraints

This article presents a composite guidance law comprising a three-stage proportional navigation (PN) structure for the simultaneous arrival of multiple missiles. Motivated by the fact that the selection of the navigation constant considerably influences the trajectory shape, the proposed composite law is designed to have different navigation constants at each stage to achieve the desired impact time. The three stages of the proposed law are configured to sequentially increase, maintain, and decrease the magnitude of the look angle by switching only the navigation constant, through which the seeker’s field-of-view constraint, which is mainly determined by the look angle, can be satisfied without additional considerations. Furthermore, the simple PN-based structure of the proposed law makes it possible to obtain an exact closed-loop solution, providing various useful information for practical implementation, such as the expected trajectory, required guidance command, and range of achievable impact time. In addition, the relevant investigations based on the theoretical analysis as well as the demonstration results obtained through the numerical simulation are presented herein.

VARIABILITY OF TRACHEAL BIFURCATION ACCORDING TO MAGNETIC RESONANCE IMAGING

Modern methods of radiological diagnostics allow to visualize in life the structural and topographic peculiarities of the structure of the human body, signifi cantly expanding the range of individual anatomical variability of its individual parts and organs. Detailed study of tracheal bifurcation and structure and topography of the main bronchi by in vivo imaging using computed tomography and magnetic resonance imaging attracts the attention of researchers, as it allows to identify and describe variation series and extreme forms of individual norms of the studied structures. The aim. Elucidation of possible variants of tracheal bifurcation and topography of the main bronchi in individuals of mature age according to magnetic resonance imaging. In the course of the work, an analysis of 18 series of anonymized magnetic resonance computed tomography of the thoracic cavity of the individuals of mature age, performed on a Siemens Avanto 1.5T, followed by processing the results with the MicroDicom operating program in 3D-COR mode. In the study of tomograms, it was determined the magnitude of the bifurcation angle of the trachea and the angles of branching of the right and left main bronchi. In the processed randomized sample, the value of the bifurcation angle of the trachea was 79±2.16°. The angle of branching of the left main bronchus was 133.14±3.52 °, and the right main bronchus – 147.72±3.39°. With the general tendency to the predominance of the right main bronchus, the analysis of a series of tomograms showed that only in 13 people (72.2%) right main bronchus was an extension of the trachea and the angle of its branching was greater than the left main bronchial angle. In 3 persons (16.7%) the values of the angles of branching of the right and left main bronchi were almost the same, and in 2 persons (11.1%) the angle of branching of the left main bronchus from the trachea was greater than the angle of branching of the right main bronchus. Identifi ed variants of bifurcation of the trachea and angles of branching of the main bronchi can be considered as variants of the individual anatomical norm of this area.

Investigation of crystal structures, energetics and isostructurality in halogen-substituted phosphoramidates

A total of 14 compounds, one unsubstituted and 13 halogen-substituted phosphoramidates, have been synthesized from unsubstituted and halogenated (fluoro-, difluoro-, chloro-, bromo-, iodo-substituted) aniline and diphenyl phosphoryl chloride to investigate their molecular assembly in solid-state structures. Amongst them, six groups were formed based on similarities in unit-cell dimensions, space group and molecular assembly of the crystal. The analysis reveals that all the crystal structures contain robust N-H...O hydrogen bonds which are the primary building blocks with ancillary interactions such as C-H...O, C-H...π, C-H...F/Cl/Br/I, F...F, F...π, I...π, Br...π, I...O and Br...O. The role of short and directional C-H...O and C-H...π interactions providing significant stabilization to the densely packed crystalline arrangement is discussed. The contribution of these interactions in stabilizing the crystalline assembly was deduced via computing total interaction energy between dimers and the overall lattice energies using the computer programs CrystalExplorer17.5 and PIXELC, respectively. Additionally, the occurrence of 3D isostructurality in phosphoradimates and their halogenated analogs was investigated using the XPac program. A comparison of the magnitudes of the torsion angles in the compounds substantiates the role of conformational flexibility in the solid state.

Spectacle correction in the complex of therapeutic measures for primary angle closure glaucoma. Preliminary report

PURPOSE. To improve the effectiveness of primary angle closure glaucoma (PACG) treatment in the initial stage in patients with hyperopia.MATERIAL AND METHODS. The study observed 18 patients (36 eyes) with the initial stage of PACG who also had low (8 subjects, 16 eyes) or moderate (10 subjects, 20 eyes) hyperopia. Study patients were divided into two groups: the main group — 12 patients (24 eyes) aged 43–67 years (mean age 55.6±1.1 years); the control group — 6 patients (12 eyes) aged 48–60 years (mean age 56.4±2.4 years). Prescribed treatment in the main group: selection and application of universal progressive correction, then laser iridecotomy (LIE) and management without pilocarpine instillations. Prescribed treatment in the control group: selection and application of monofocal correction for near vision, then LIE and instillations of 1% pilocarpine solution 3 times a day. All patients underwent visometry with correction, refractometry, ophthalmoscopy, tonometry, tonography, gonio-scopy, optical coherence tomography of the anterior eye segment, ultrasound biometry. Indicators of hydrodynamics and parameters of the anterior chamber were recorded before using spectacles correction, after the start of correction, after LIE, and 1 month after the start of all therapeutic measures.RESULTS. The use of progressive spectacle correction led to a significant decrease of true intraocular pressure (IOP) (p<0.001), an improvement of aqueous humor outflow (p<0.05) and an increase in the size of anterior chamber angle (p<0.001). Performing LIE in patients of the main group did not significantly change these indicators. The results obtained in this group made it possible to abandon the use of pilocarpine. In patients of the control group, the improvement in aqueous humor outflow (p<0.001) and increase in the size of anterior chamber angle (p<0.002) were more significant after LIE than after prescription of adequate monofocal correction for near vision (p<0.02–0.05 and p<0.2, respectively).CONCLUSION. The use of progressive spectacle correction in patients with hyperopia and initial stage of PACG before LIE leads to normalization of hydrodynamic parameters and an increase in the magnitude of anterior chamber angle without the use of miotic drugs. Prescription of progressive spectacle correction is advisable in these patients as a part of the complex of therapeutic measures aimed at normalizing ocular hydrodynamics.

Experimental Analysis on Bending Behavior of Non‐Alloy Carbon Steel Sheets Using Laser‐Forming Process

Herein, the laser‐forming process of nonalloy carbon steel sheets is investigated experimentally. First, it is necessary to consider how the material factor of carbon steels affects the bend angle during the laser‐forming process. Therefore, bend angle results of three grades of carbon steel sheets, including St 14, CK 45, and CK 75, are studied based on the Taguchi design of the experiment. Then, the effects of process parameters, as named laser power, beam diameter, and scan rate on bend angle, are investigated for the most formable steel. The results show that the steel grade factor exhibits an obvious effect on bend angle, but the laser power and laser beam scan rate as process parameters play a more dominant role in determining the magnitude of the bend angle. Moreover, for St 14 with the highest bend angle, the scan rate has the most significant effect on the bend angle. In addition, the laser beam diameter exhibits the least significant effect on the bend angle. It can be concluded that the laser scan rate is the fastest factor to adjust and the most efficient control parameter for the bend angle.

Irregular deviation of flight control surface monitoring for jet transport aircraft

PurposeThe purpose of this paper is to present the irregular deviation examination of flight control surfaces and the potential problem diagnosis of irregular deviations for the jet transport aircraft. A four-jet transport aircraft at transonic flight in cruise phase is the study case of the present article.Design/methodology/approachThe standard lift-to-drag ratio (L/D) and flight dynamic models are established through flight data mining and the fuzzy logic modeling technique based on the flight data of quick access recorder available in the Flight Operations Quality Assurance (FOQA) program of the airlines. The irregular deviations of flight control surfaces are examined by the standard L/D model-predicted results through sensitivity analysis. The contribution values in L/D deficiency are predicted by the deviations and the L/D derivatives of all influencing variables in Taylor series expansion. The potential problems due to irregular deviations can be excavated by the flight dynamic models through the analysis of in-flight stability and controllability.FindingsThe magnitude of stabilizer angle to the deficiency of L/D is the largest among the four control surfaces and elevator is the second one through the judgment of contribution values in L/D deficiency. The stabilizer has irregular deviations with obvious endplay problems of jackscrew, as found in the present study. The stabilizer is suggested to have the unscheduled maintenance for the flight control rigging.Research limitations/implicationsThe specific transport aircraft of the standard L/D model should be the best one in L/D performance among all transport aircraft in the fleet of the airlines. The present method is a new concept to monitor the irregular deviation of flight control surface. The study case of the four-jet transport aircraft at transonic flight in cruise phase is illustrated as the standard L/D mode. The required flight data of monitored flight is requested to eliminate the biases through compatibility checks. The flight data of study case in the present study is also illustrated as monitored flight data.Practical implicationsTo diagnose the irregular deviations of flight control surface deflected angles with contributing to the L/D deficiency estimation is an innovation to improve the flight data analysis of FOQA program for airlines. If the irregular deviation problems of control surfaces can be fixed after rigging in maintenance, the goal of flight safety and aviation fuel saving will be achieved.Social implicationsThe flight control surface rigging of unscheduled maintenance is not expected to coincide with an airline’s peak season or unavailable space in hangar. The optimal time of unscheduled maintenance for the flight control rigging will be easily decided through the correlations between excessive fuel cost and flight safety.Originality/valueThis method can be used to assist airlines to monitor irregular angular positions of flight control surfaces as a complementary tool for management to improve aviation safety, operation and operational efficiency.

Influence of Liquid Hydrogen Diffusion on Nonlinear Mixed Convective Circulation around a Yawed Cylinder

A yawed cylinder is a cylinder inclined in the plane of a flowing liquid. The liquid flow past the yawed cylinder is important for practice, namely, for bubble suppression and control of the boundary layer transition in undersea applications. It should be noted that an inclined cylinder characterizes an asymmetrical behavior of fluid flow and heat transfer. Energy and mass transference characteristics of a steady nonlinear convective flow over the yawed cylinder by accounting for chemically reactive species and viscous dissipation are analyzed in this investigation. The differential equations defining the boundary layer parameters are then transformed into a dimensionless view, taking into account the non-similar transformation. It should be noted that the governing equations have been written using the conservation laws of mass, momentum, energy, and concentration. These considered equations allow the simulation of the analyzed phenomenon using numerical techniques. Further, quasilinearization and implicit finite difference approximation are used to work out the non-dimensional governing equations. A parametric investigation of all the pertinent characteristics accompanies this. A descriptive system of computation outcomes for the velocity, temperature, and concentration patterns, the drag coefficients, Nu and Sh, is demonstrated by graphs. Enhancing the magnitudes of the Eckert number raises the temperature pattern while energy transport strength is reduced. As the species concentration profile diminishes, the mass transfer characteristics are enhanced for raising magnitudes of the nonlinear chemical reaction parameter. Further, a velocity profile along the chordwise direction rises with enhancing magnitudes of nonlinear convection characteristics and yaw angle. Furthermore, the velocity pattern along the spanwise direction enhances with the growing magnitudes of yaw angle. For assisting buoyancy flow, the friction parameter at the border in the spanwise direction enhances with rising values of yaw angle.

Effect of the magnitude of sub-boundary angles on the abnormal grain growth rate of Goss grains in Fe-3%Si steel

In spites of extensive studies, the selective abnormal grain growth (AGG) of Goss grains in Fe-3%Si steel remains still unclear. Here, the effect of the magnitude of sub-boundary angles on AGG behavior was investigated both by computer simulations and experiments. In 3-dimensional Monte Carlo simulations of grain growth based on the realistic grain boundary energy distribution data, the grains of Goss orientation, which are given the sub-boundaries, grew abnormally and smaller sub-boundary energies resulted in larger Goss grains. Additionally, a Fe-3%Si steel, after primary recrystallization, was heated to 1050 °C to induce AGG. Measurements of sub-boundary angles for three different sizes of abnormally growing Goss grains by synchrotron X-ray microdiffraction after the initial stage of secondary recrystallization showed that the misorientation of the sub-boundary angles was 0.41° for the small Goss grain of 734 μm. Moreover, the average misorientation of sub-boundary angles was 0.33° for the medium Goss grain of 1050 μm and 0.25° for the large Goss grain of 2978 μm. In contrast, the average misorientation angles of the sub-boundaries after the final stage of secondary recrystallization were only 0.05°. The results indicate that the sub-boundary angle is a determining parameter for the size of abnormally growing grains. • The effect of sub-boundary angle on abnormal grain growth behavior was investigated. • In the simulations, the Goss grains with small sub-boundary energies grew larger. • In the experiments, the large Goss grains tended to have small sub-boundary angles. • The sub-boundary angle should be a key parameter of abnormally growing Goss grains.

A Plan to Reclaim Deuterons Escaping from the Loss Cone of a Magnetic Mirror

Research on magnetic mirror reactors has had two serious problems since the beginning stage. One is the magnetohydrodynamic instability due to the negative curvature of the magnetic field lines around the center region of a mirror bottle. Another is the loss of charged particles escaping from the loss cone of a magnetic mirror. We have continued to inquire into a means to solve the latter problem. We here propose a new way which will be able to make a magnitude of a loss angle of a magnetic mirror for deuterons virtually zero.

Режимы работы полупроводникового вольтодобавочного устройства для регулирования напряжения на тяговых подстанциях

One of the ways to strengthen the DC power supply system of the main railways of Russia is the use of semiconductor voltage-boosting devices for voltage regulation at traction substations. The work of diode and thyristor bridge rectifiers connected in series with it is considered in the article. The analysis is performed under the condition that active and reactive resistances of the supply network and the converter transformer are zero. It was found out that, depending on the magnitude of the control angle, such a converter can have two modes of operation. For these modes, time diagrams of the rectified voltages of both the thyristor bridge and the entire converter are constructed. Expressions are obtained for determining the average values of the rectified voltages of a 12-pulse diode rectifier of a serial type and a 12-pulse thyristor rectifier of a parallel type connected in series with it. The calculation of the adjustment characteristics of this adjustable converter is performed.

Relationship Between the Results of Arm Swing Data From the OpenPose-Based Gait Analysis System and MDS-UPDRS Scores

Motor functions of individuals with Parkinson’s disease (PD) have been studied by many methods such as sensors, 3D measurement devices, smartphone applications, and deep learning tools. OpenPose is a deep learning tool for human pose estimation. However, few studies have focused only on gait arm swing and analyzed it separately from that of healthy subjects. Furthermore, none of the previous studies compared arm swing data measured from video images using OpenPose or other methods with the relevant items in the MDS-UPDRS. In this study, we calculated the thresholds to distinguish between normal and abnormal gaits from the data of healthy subjects. We compared the peak-to-peak (P-P) data of the left and right arm swing and arm swing asymmetry (ASA) using an OpenPose-based gait analysis system developed in our previous study with the MDS-UPDRS scores. It showed 72.73–82.35% accuracy; thus, the threshold between normal and abnormal gaits can be improved. From these results, we can conclude that there is a significant relationship between the MDS-UPDRS score and the magnitude of the gait arm swing angle measured using the OpenPose-based gait analysis system. The method proposed in this study is simpler and easier to use in clinical practice than the methods proposed in previous studies. Moreover, videos of timed up-and-go (TUG) tests can be used. We hope that this study will enable the estimation and early detection of PD symptoms using a simpler index and method.

ACCURACY TEST OF SUPERMARKET'S MUSHOLA QIBLA DIRECTION IN CIREBON CITY

This study aims to answer the questions that become the formulation of the problem “How is the method of measuring the Qibla direction of the supermarket prayer room in Cirebon City” and “How to analyze the accuracy of the supermarket prayer room Qibla direction in Cirebon City.” This study uses qualitative research; the data collected uses observation, interviews, documentation, and literature study. They were then analyzed by the descriptive analysis method in narration. The results of this study: that the Qibla direction of the supermarket in Cirebon City has all measured the Qibla direction. The method of measuring the Qibla direction was carried out by the musala supermarket, where the author’s research uses the Qibla compass and the Qibla direction application on the smartphone. Of course, using the Qibla direction application on a smartphone is an inaccurate method. This method’s method is partly an error in determining the Qibla direction. Due to his ignorance of astronomy in measuring the Qibla direction and ignorance of the magnitude of the Qibla direction angle in the Cirebon City area, resulting in the Qibla direction of the supermarket in the Cirebon City area experiencing a wrong Qibla direction.

A Retrospective Analysis of the L3–L4 Disc and Spinopelvic Parameters on Outcomes in Thoracolumbar Fusion: Was Art Steffee Right?

To determine whether the L3-L4 disc angle may be a surrogate marker for global lumbar alignment in thoracolumbar fusion surgery and to explore the relationship between radiographic and patient-reported outcomes after thoracolumbar fusion surgery. Retrospective chart review was conducted on patients who had undergone a lumbar fusion involving levels from T9 to pelvis. EuroQol-Five Dimension (EQ-5D-3L) scores and adverse events including adjacent-segment disease and degeneration, pseudoarthrosis, proximal junctional kyphosis, stenosis, and reoperation were collected. Pre- and postoperative spinopelvic parameters were measured on weight-bearing radiographs, with the L3-L4 disc angle of novel interest. Univariate logistic and linear regression were performed to assess the associations of radiographic parameters with adverse event incidence and improvement in EQ-5D-3L, respectively. In total, 182 patients met inclusion criteria. Univariable analysis revealed that increased magnitude of L3-L4 disc angle, anterior pelvic tilt, and pelvic incidence measures are associated with increased likelihood of developing postoperative adverse events. Conversely, increased lumbar lordosis demonstrated a decreased incidence of developing a postoperative adverse event. Linear regression showed that radiographic parameters did not significantly correlate with postoperative EQ-5D-3L scores, although scores were significantly improved postfusion in all dimensions except Self-Care (P= 0.51). L3-L4 disc angle magnitude may serve as a surrogate marker of global lumbar alignment. The degree of spinopelvic alignment did not correlate to improvement in EQ-5D-3L score in the present study, suggesting that quality of life metric change may not be a sensitive or specific marker of postfusion alignment.

УПРАВЛІННЯ СУДНОМ ЗА ЗБУРЕННЯМ ПРИ ПОСЛІДОВНОМУ ЗЧИСЛЕННІ ТА ОБСЕРВАЦІЇ РУХУ СУДНА

Controllability is an important maritime quality that determines the efficiency of ship handling. When developing course control systems, it is necessary to take into account the operational characteristics of the vessel, as well as external factors affecting it. The complexity of ship handling, as an object of handling, arises due to the continuous influence of various factors that affect the controllability of the ship. The environmental conditions in which the course management task has to be solved are diverse - stormy weather, ice conditions, shallow water, tides, restricted waters(congested areas), proximity of other vessels, etc. All these factors cannot be comprehensively taken into account by traditional mathematical methods, while ensuring the necessary adequacy of real processes. This paper considers existing approaches to controlling the movement of a ship on a course, such as course control, disturbance control, ship movement control on a course based on the principle of long-term prediction, lateral deviation, intellectual approaches to ship control. The most necessary way to improve the quality of the vessel's course is to control the disturbance by consistently calculating and observing the vessel's movement. The main disturbing effect in stabilizing the course is caused by sea waves. In stormy weather, forced oscillations are imposed on the ship's own motions on the course. The amplitude and period of yawing depend on the level of sea state, the direction and strength of the wind, the tonnage of the vessel, its loading condition, speed, effectiveness of the rudder and the law of control. There is a need to increase the accuracy of determining the direct relationship between the measured value of the external perturbation and the magnitude of the yaw angle. The article provides an algorithm for calculating the return of the vessel to the path line, taking into account the modulus and direction of natural disturbance obtained as a result of observation of the ship's position.

Analysis of Geometric and Hemodynamic Profiles in Rat Arteriovenous Fistula Following PDE5A Inhibition.

Arteriovenous fistula (AVF) is essential for chronic kidney disease (CKD) patients on hemodialysis, but treatment for AVF maturation failure remains an unmet clinical need. Successful AVF remodeling occurs through sufficient lumen expansion to increase AVF blood flow and lumen area. Aberrant blood flow is thought to impair AVF remodeling, but previous literature has largely focused on hemodynamics averaged over the entire AVF or at a single location. We hypothesized that hemodynamics is heterogeneous, and thus any treatment’s effect size is heterogeneous in the AVF. To test our hypothesis, we used the PDE5A inhibitor sildenafil to treat AVFs in a rat model and performed magnetic resonance imaging (MRI) based computational fluid dynamics (CFD) to generate a detailed spatial profile of hemodynamics in AVFs. 90 mg/kg of sildenafil was administered to rats in their drinking water for 14 days. On day 14 femoral AVFs were created in rats and sildenafil treatment continued for another 21 days. 21 days post-AVF creation, rats underwent non-contrast MRI for CFD and geometrical analysis. Lumen cross-sectional area (CSA) and flow rate were used to quantify AVF remodeling. Parameters used to describe aberrant blood flow include velocity magnitude, wall shear stress (WSS), oscillatory shear index (OSI), and vorticity. Geometrical parameters include arterial-venous (A-V) distance, anastomosis angle, tortuosity, and nonplanarity angle magnitude. When averaged across the entire AVF, sildenafil treated rats had significantly higher CSA, flow rate, velocity, WSS, OSI, and vorticity than control rats. To analyze heterogeneity, the vein was separated into zones: 0–5, 5–10, 10–15, and 15–20 mm from the anastomosis. In both groups: 1) CSA increased from the 0–5 to 15–20 zone; 2) velocity, WSS, and vorticity were highest in the 0–5 zone and dropped significantly thereafter; and 3) OSI increased at the 5–10 zone and then decreased gradually. Thus, the effect size of sildenafil on AVF remodeling and the relationship between hemodynamics and AVF remodeling depend on location. There was no significant difference between control and sildenafil groups for the other geometric parameters. Rats tolerated sildenafil treatment well, and our results suggest that sildenafil may be a safe and effective therapy for AVF maturation.

COMPUTATIONAL ANALYSIS ON HEAVE AND PITCH MOTIONS PERFORMANCE OF A HYDROFOIL SHIP

Hydrofoil ship usually experiences high resistance and excessive heave and pitch that may lead to downgrade her seakeeping performance. Therefore, a reliable investigation on prediction of a seakeeping performance of a hydrofoil ship in head-seas is obviously required. To achieve this objective, an analysis of Computational Fluid Dynamic (CFD) approach on hydrofoil ship motion is then proposed. Several parameters such as angle of stern foil and Froude Number have been accordingly taken into account in the simulation, where the fore foil angle is constantly 5 . In general, the results revealed that the increase of the stern foil angle was proportional to the heave motion of the hydrofoil ship. As compared to the magnitude of the stern foil angle of 5 and 10 , the heave motion of the hydrofoil ship has sufficiently decreased at the stern foil angle of 7.5, which leads to have a better seakeeping performance. Furthermore, the subsequent increase of Froude number pointing towards reduction of heave motion, which was inversely proportional to the magnitude of her pitch motion. Inherently, these have led to degrade of the hydrofoil ship seakeeping performances presented in the form of high Response Amplitude Operators (RAO). In general, this CFD simulation is very beneficial to ensure an operational effectiveness of hydrofoil design in high sea states with respect to the aforementioned design parameter.

Molecular Insight into the β-Sheet Twist and Related Morphology of Self-Assembled Peptide Amphiphile Ribbons.

Self-assembly of high-aspect-ratio filaments containing β-sheets has attracted much attention due to potential use in bioengineering and biomedicine. However, precisely predicting the assembled morphologies remains a grand challenge because of insufficient understanding of the self-assembly process. We employed an atomistic model to study the self-assembly of peptide amphiphiles (PAs) containing valine-glutamic acid (VE) dimeric repeats. By changing of the sequence length, the assembly morphology changes from flat ribbon to left-handed twisted ribbon, implying a relationship between β-sheet twist and strength of interstrand hydrogen bonds. The calculations are used to quantify this relationship including both magnitude and sign of the ribbon twist angle. Interestingly, a change in chirality is observed when we introduce the RGD epitope into the C-terminal of VE repeats, suggesting arginine and glycine's role in suppressing right-handed β-sheet formation. This study provides insight into the relationship between β-sheet twist and self-assembled nanostructures including a possible design rule for PA self-assembly.

Risk-Controlled Wellbore Stability Criterion Based on a Machine-Learning-Assisted Finite-Element Model

Summary In certain drilling scenarios, the mud weight required to completely prevent wellbore enlargement can be impractically high. In such cases, what is known as risk-controlled wellbore stability criterion is introduced. This criterion allows for a certain and manageable level of wellbore enlargements to take place. Conventionally, the allowable level of wellbore enlargements in this type of model has always been based on the magnitude of the breakout angle. However, wellbore enlargements, as seen in caliper and image logs, can be highly irregular in terms of their distribution around the wellbore. This means that risk controlling wellbore stability through the breakout angle parameter can be insufficient. Instead, the total volume of cavings is introduced as the risk-control parameter. Unlike the breakout angle, the total volume of cavings can be coupled with a suitable hydraulics model to determine the threshold of manageable enlargement. The volume of cavings is determined using a machine-learning (ML)-assisted 3D elastoplastic finite-element model (FEM). The model implementation is first validated through experimental data. Next, a full data set from offset wells is used to populate and train the model. The trained model is then used to produce estimations of risk-controlled stability mud weights for different drilling scenarios. The model results are compared against those produced by conventional methods. Finally, both the FEM-ML model and the conventional method's results are compared against the drilling experience of the offset wells. The results illustrate how this methodology provides a more comprehensive and new solution to risk controlling wellbore stability.

Boltzmann Equation with Cutoff Rutherford Scattering Cross Section Near Maxwellian

The well-known Rutherford differential cross section, denoted by $ d\Omega/d\sigma$, corresponds to a two body interaction with Coulomb potential. It leads to the logarithmically divergence of the momentum transfer (or the transport cross section) which is described by $$\int_{{\mathbb S}^2} (1-\cos\theta) \frac{d\Omega}{d\sigma} d\sigma\sim \int_0^{\pi} \theta^{-1}d\theta. $$ Here $\theta$ is the deviation angle in the scattering event. Due to screening effect, physically one can assume that $\theta_{\min}$ is the order of magnitude of the smallest angles for which the scattering can still be regarded as Coulomb scattering. Under ad hoc cutoff $\theta \geq \theta_{\min}$ on the deviation angle, L. D. Landau derived a new equation in \cite{landau1936transport} for the weakly interacting gas which is now referred to as the Fokker-Planck-Landau or Landau equation. In the present work, we establish a unified framework to justify Landau's formal derivation in \cite{landau1936transport} and the so-called Landau approximation problem proposed in \cite{alexandre2004landau} in the close-to-equilibrium regime. Precisely, (i). we prove global well-posedness of the Boltzmann equation with cutoff Rutherford cross section which is perhaps the most singular kernel both in relative velocity and deviation angle. (ii). we prove a global-in-time error estimate between solutions to Boltzmann and Landau equations with logarithm accuracy, which is consistent with the famous Coulomb logarithm. Key ingredients into the proofs of these results include a complete coercivity estimate of the linearized Boltzmann collision operator, a uniform spectral gap estimate and a novel linear-quasilinear method.