Transverse Stability Research Articles

A novel multi-layer isolation structure for transverse stabilization inspired by neck structure

A novel multi-layer isolation structure for transverse stabilization inspired by neck structure

Novel controller for the coupled surge-pitch problem by controlling the metacentric height of sandglass-type FDPSO

Compared with the conventional vessels and platforms, the water plane area of the sandglass-type FDPSO (floating, drilling, production, storage and offloading unit) under upright condition is smaller, which makes its longitudinal metacentric height lower and natural frequency of pitch motion smaller. As a result, coupled surge and pitch motion problem would be caused unexpectedly. In this paper, from the perspective of controlling the metacentric height, a novel dynamic positioning (DP) controller is proposed. The proposed controller can make the natural frequencies of surge and pitch motions away from each other. Consequently, both the surge and pitch motions satisfy the positioning accuracy. Besides, the coupled resonant and non-resonant zones with the control parameters are investigated. Considering the system stability, positioning accuracy and power consumption, a complete analysis process of optimal control parameter selection is proposed. By comparisons with two existing control laws, the novel controller is established with better performances on robustness, positioning accuracy and energy consumption.

Results of an international benchmark study on numerical simulation of flooding and motions of a damaged ropax ship

Survivability of damaged ships, especially ro-ro/passenger (ropax) vessels, is of paramount interest. Nowadays, time-domain simulation of flooding and motions of damaged ships are more frequently performed to obtain a more realistic overview of the actual survivability in case of a flooding accident. An international benchmark study on simulation of flooding and motions of damaged ropax vessels was conducted within the EU Horizon 2020 project FLARE, using new dedicated model tests as a reference. The test cases include transient flooding in both calm water and in irregular beam seas, as well as gradual flooding and capsizing in beam seas. The studied damage case is a two-compartment collision damage, and the studied intact metacentric height values were lower than the statutory requirements to achieve also capsize cases. Numerical results were carefully compared against measurement data from the model tests. In transient flooding cases the capsize conditions were generally detected well by most codes. However, much variation was observed in the internal flooding and capsize mechanisms. For gradual flooding in beam seas, the results for capsize rate and time-to-capsize were characterized by significant variability among the codes. Results indicate that more research is needed to further improve the time-domain flooding simulation methods to correctly capture both transient flooding phenomena and motions of damaged ship in high waves.

Traveling waves and transverse instability for the fractional Kadomtsev–Petviashvili equation

AbstractOf concern are traveling wave solutions for the fractional Kadomtsev–Petviashvili (fKP) equation. The existence of periodically modulated solitary wave solutions is proved by dimension‐breaking bifurcation. Moreover, the line solitary wave solutions and their transverse (in)stability are discussed. Analogous to the classical Kadmomtsev–Petviashvili (KP) equation, the fKP equation comes in two versions: fKP‐I and fKP‐II. We show that the line solitary waves of fKP‐I equation are transversely linearly instable. We also perform numerical experiments to observe the (in)stability dynamics of line solitary waves for both fKP‐I and fKP‐II equations.

Three-dimensional analysis of mandible ramus morphology and transverse stability after intraoral vertical ramus osteotomy

ObjectivesThe purpose of this study was to investigate short- and long-term postoperative changes of both morphology and transverse stability in mandibular ramus after intraoral vertical ramus osteotomy (IVRO) in patients with jaw deformity using three-dimensional (3D) orthognathic surgery planning treatment software for measurement of distances and angles.Study designThis retrospective study included consecutive patients with skeletal Class III malocclusion who had undergone intraoral vertical ramus osteotomy and computed tomography images before (T0), immediately after (T1), and 1 year after (T2) surgery. Reference points, reference lines and evaluation items were designated on the reconstructed 3D surface models to measure distances, angles and volume. The average values at T0, T1, T2 and time-dependent changes in variables were obtained.ResultsAfter surgery, the condylar length, ramal height, mandibular body length and mandibular ramus volume were significantly decreased (P < 0.01), while clinically insignificant change was observed from T1 to T2. The angular length was increased immediately after surgery (P < 0.05), but it was decreased 1 year after surgery (P < 0.05). Lateral ramal inclination showed significant increase after surgery (P < 0.05) and maintained at T2.ConclusionChanges in the morphology of the mandibular ramus caused by IVRO do not obviously bring negative effect on facial appearance. Furthermore, despite position and angle of mandibular ramus changed after IVRO, good transverse stability was observed postoperatively. Therefore, IVRO technique can be safely used without compromising esthetic results.

ПРАКТИКА ИСПОЛЬЗОВАНИЯ ТЕХНИЧЕСКИХ ТКАНЕЙ В ПРОИЗВОДСТВЕ ТЕПЛОСТОЙКИХ РУКАВОВ

the article has developed and mastered promising technologies for the production of heat-resistant metallurgical hoses, which include the use of synthetic materials for the power frame and fire-resistant - cover fibrous materials. Experimental studies have been carried out to reduce the material consumption of the production of sleeves, due to changes in manufacturing technology at the stage of cutting the strips of the power frame and assembling the sleeves. A sleeve manufacturing technology is described, which provides for the introduction of a wire spiral into the sleeve design to protect the sleeves from loss of transverse stability and reduce the bending radius. Technical cord materials for the manufacture of a power frame for sleeves of various types in production are considered. The technology of protecting the outer surface has been mastered, providing for the creation of bumpers of various design schemes. In order to increase the temperature resistance of the operation of metallurgical heat-resistant sleeves, a technology has been created for the manufacture of sleeves based on non-flammable and fire-resistant fabric materials covering the sleeves on the outer surface. The operation of the hoses showed the correctness of the developed technologies and the choice of appropriate materials. Research work on the development of new fire-resistant materials for heat-resistant hoses has been carried out. The prospects of using innovative technology for manufacturing heat-resistant metallurgical hoses are noted

A Methodology for Simply Evaluating the Safety of a Passenger Ship Stability Using the Index for the Intact Stability Appraisal Module.

To evaluate the safety of passenger ships’ stability, ten stability parameters should be calculated. However, since the process for calculating all stability parameters is complex without a ship loading program, a convenient methodology to simply calculate them and evaluate the safety condition of a passenger ship is required to alert the hazard to a captain, officer, and crew. The Index for Passenger Ship Intact Stability Appraisal Module (IPSAM) is proposed herein. According to the value of a passenger ship’s metacentric height (GM) which could be calculated by the ship’s roll period measured by sensors in real-time, IPSAM simply calculates nine intact stability parameters except for and proposes the present stability status as a Single Intact Stability Index (SISI). It helps crews easily recognize the safety of passenger ships’ stability as a decision support system in real-time. Based on the intact stability parameters of 331 loading conditions of 11 passenger ships, empirical formulas for IPSAM were derived. To verify the empirical formulas of IPSAM, the stability parameters of a passenger ship in 20 loading conditions were calculated using proposed empirical formulas and the principal calculation methods respectively, then compared. Additionally, the result of the SISI of 20 loading conditions successfully indicates the danger as the value of the SISI under 1.0 of the three loading conditions that do not satisfy the IMO intact stability requirements.

Minimally Invasive Chevron Akin: Locking The Metatarsal-Cuneiform Joint.

Minimally Invasive Chevron Akin (MICA) can be used to treat hallux valgus (HV) associated with a hypermobility of the first metatarsal-cuneiform joint (1MTCJ). The aim of this study was to perform a radiographic analysis of the MICA, focused on evaluating the 1MTCJ. Forty patients (50 feet) with moderate to severe HV underwent a MICA procedure. Radiographic analysis included hallux valgus angle (HVA), intermetatarsal angles between the first and second rays (IMA), the intermetatarsal angle between the proximal fragment of the osteotomy and the second ray (IAPF) and the distance between a point 3 cm distal from the base of the second metatarsal and a point located at the same height for the first metatarsal base (Dist 1-2). The IAPF was compared with the preoperative IMA, and the other parameters were compared preoperatively and postoperatively. The radiographic complications were also recorded. Most patients were female (92%). The mean age was 50.4 years (SD = 16.1) and the mean follow-up was 16.1 months (SD = 3.5). The average HVA improved from 32.5° to 7.3°, and the average IMA from 14.2° to 4.2°. The IAPF and Dist1-2 values showed an increase of 4.8° and 4.0 mm respectively. There were no radiographic complications. Conclusion. Minimally invasive Chevron Akin promotes a great correction of the moderate to severe HV conventional parameters and increase the transversal stability of the 1MTCJ fixing this joint as medial as possible. Level IV, case series.

Обоснование параметров балластных ем- костей мобильного причала для перевалки лесоматериалов

The use of a mobile small-sized berth, the design of which was proposed by the authors in the previous paper, significantly increases capacity and reduces the cost of timber transshipment. When towing the berth over large distances, its ballast tanks are empty, which ensures that draft and water resistance to movement are minimized. At the point of operation the leveling ballast tank is filled with water until the top surface of the berth is leveled. In this position, the berth is moved locally in case of significant changes of the water level in the reservoir. Due to manufacturability and minimization of the volume of the leveling tank, it is designed as a part of the inner space at the berth stern, separated by a vertical wall. The permutation ballast tank is filled with water to submerge the berth until it leans on the leveled coastal slope. Water is pumped out of the tank to make the berth float during its local permutations. In this case, a significant trim should not be allowed. The lower point of the longitudinal section of the permutation tank was provided at the intersection of the berth bottom and the vertical, which bisects the waterline upon completion of the alignment. Algorithms have been developed for determining the position of the vertical wall of the leveling tank and the position and shape of the walls of the permutation tank. The distance of the vertical wall from the lower point of the berth and the coordinates of the points of the profiles of the left curved and right walls of the permutation tank were determined for a conditional berth of unit height and width. The coordinates were used to derive empirical dependencies. The values of the calculated metacentric heights verified the longitudinal and transverse stability of the berth in all positions. Experimental validation on a physical model of the berth confirmed the correctness of the results. Transition to the correct dimensions of the longitudinal profile from the conditional is assumed with the proportions retained. For citation: Posypanov S.V., Chuprakov V.O. Justification of Ballast Tank Parameters of a Mobile Berth for Timber Transshipment. Lesnoy Zhurnal [Russian Forestry Journal], 2022, no. 1, pp. 143–154. DOI: 10.37482/0536-1036-2022-1-143-154

Numerical Investigation on Flood Water Sloshing Influence on Intact and Damaged Stability of Ship

Sloshing affects the intact and damage stability of the ship, which causes variation in dynamic metacentric height (GM) under critical load conditions. The transient flooding soon after the ship damage is analyzed, with floodwater accumulation in large space and causing the ship to suffer huge heel angles. The ship motion and stability changes when sloshing becomes high in partially flooded compartments. Most of the previous researches focus on the motion response of ship alone, hence the variation of stability due to sloshing is to be more critically studied. In the present study, three critical damage locations are identified and flooding through these locations are analyzed using the volume of fluids method. The method focus on finding damage ship motion response, flood water dynamics, and coupled dynamics of both. This is studied using the numerical method FLOW3D. Motion and stability behaviour will be different for different damage locations; hence portside, starboard-side, and aft-end bottom damage cases are considered. The effect of compartment shape and damage location on motion response and stability of the damaged ship is highlighted.

Seaworthiness and Stability Analysis of a Pontoon for Holiday House

In this paper, the methodology of seaworthiness and stability analysis of a pontoon for holiday house has described. A 3D model of the pontoon was modelled in the NAPA software to perform hydrostatic analysis. It is necessary to emphasize the fact that hydrostatic analysis has been made for several drafts and trims of pontoons. The hydrostatic analysis yielded data such as displacement, moulded volume, longitudinal centre of buoyancy, the transverse metacentric height, change of displacement, moment to change trim, and more. This part of the analysis also includes the loading scale from which we can see the deadweight at a given draft. Further, it is necessary to make weight study to get moulded displacement for pontoon for a holiday house. The pontoon also includes capacity tanks, so it is necessary to know the accurate dimensions of the tanks and their position for further analysis. It is necessary to know the exact geometry of the tanks because of the free surface effect. When calculating the stability of the pontoon, it is necessary to determine the minimum metacentric height and the maximum distance from the keel to the centre of gravity. Intact stability conditions must be met for GM limit curves and also for KG curves. Intact stability criteria of the pontoon were tested for four loading conditions: lightship, pontoon with 10% consumables without passengers, pontoon with 100% consumables with passengers, pontoon with 50% consumables with passengers. It is important to emphasize that all tasks meet the stability criteria.

PREDICTION OF RESIDUAL RESISTANCE OF A TRIMARAN VESSEL BY USING AN ARTIFICIAL NEURAL NETWORK

Trimaran hull forms have been popular recently in both commercial and military usage due to reduction in resistance at high speeds, better stability, and greater deck area compared to conventional monohull vessels. Determination of the location of the side hulls is most critical to get higher hydrodynamic performance. Therefore, many studies in the literature are related to defining the location of the side hulls for trimaran vessels. Most of the studies have been carried out experimentally or numerically. In this study, an artificial neural network (ANN) model was used to predict the residual resistance coefficient of a trimaran model. The model uses four parameters which are the transverse and longitudinal positions of the side hulls, the longitudinal centre of buoyancy and the Froude number to predict the residual resistance of the trimaran model. The experimental data of the trimaran model were used to train the neural network model in order to develop a more reliable model. Several neural network models were developed and tested to find the one with minimum error. The study showed that the residual resistance coefficients of the trimaran model were predicted with high accuracy levels compared to the model experimental data. It was also shown that an ANN is a useful alternative method to model tests and numerical simulations. The developed model can be used to reduce the number of model tests or numerical simulations as well as to obtain the optimum location of the side hulls in terms of resistance.

Alternative Method for Stability Assessment of Indonesian Traditional Wooden Boats

Due to the small down-flooding angle, the available intact stability criteria were difficult to apply to an Indonesian traditional wooden. This paper discusses the application of the dead ship criteria of Second Generation Intact Stability Criteria as an alternative method to assess the stability of the Indonesian traditional wooden boats. The hydrodynamics factors correspond to the formula to calculate the heel angle due to wave were determined by model experiments. The calculations were conducted for four different down-flooding angles consisting of 20 degrees, 25 degrees, 30 degrees and 35 degrees with scattered wave data of Lombok Strait. The results showed that the critical metacentric height decreases if the down-flooding angle increases. The minimum area under the righting arm curve up to the down-flooding angle tends to be independent of the down-flooding angle. The capsizing index corresponds to the critical metacentric height decreased when the down-flooding angle increased. These results showed that the method to assess ship stability in the Second Generation Intact Stability Criteria could be used to evaluate the stability of the Indonesian traditional wooden boats.

Методика расчета базового компонента риска травмирования при опрокидывании автомобиля в частных задачах дорожно-транспортной экспертизы

This article deals with the method of solving private tasks of road traffic accident examination for accidents with the car rolls over and the use of injury risk assessment in these tasks. The calculation method is based on the results of the analysis of the CDS (Crashworthiness Data System, which is an emergency safety data system) and FARS (Fatality Analysis Reporting System, which is a reporting system for the analysis of road deaths) databases. A new dependence of the change of the basic risk component on the static coefficient of transverse stability in comparison with the known foreign analogues is given.

THE INFLUENCE OF THE FRAME LOAD REGULATOR ON THE TRANSVERSE STABILITY OF THE KAMAZ-5350 TRUCK

When providing transport work and driving a car in conditions of a transverse slope, it is often necessary to face the effect of uncontrolled movement of cargo on the body platform, which causes a redistribution of the load on the movers located on the same wheel axle. In addition, when transporting bulk cargo, they are poured out of the body, especially seeds of agricultural crops, which ultimately increases losses. (Research purpose) The research purpose is in experimental tests of the "Frame Load Regulator" device using a KamAZ-5350. (Materials and methods) Great difficulties arise when one of the propellers fails (damage or puncture of a wheel) located on one axis, directly within the field, since replacing the propeller in the field at the weak surface is a very time-consuming operation. One of the rational ways to operate cars in these conditions is the automatic redistribution of the load on the serviceable engine, which allows you to reduce the vertical load on the damaged engine and continue the movement of the unit. (Results and discussion) The article presents the results of an experimental test of the frame load regulator, made under RF patent No. 166665, on the transverse stability of a truck on the example of the KamAZ-5350 model in the conditions of agricultural production in the Amur region. (Conclusions) The relevance of the use of a framework load regulator in the technological process of field operations in the agro-industrial complex is described. The proposed frame load regulator is a highly efficient design with high reliability and low cost, which allows you to redistribute the load between the propellers located on the same axis when one of them fails.

Long term dental transversal stability of Class II division 1 treated with cervical headgear.

ABSTRACTIntroduction: In several conditions, outcome stability is a great challenge for Orthodontics. Previous studies have reported that relapse commonly occurs along the years after orthodontic treatment finishing. Objective: The aim of the present study was to evaluate in the long-term transversal dental arch changes of Class II division 1 patients treated with cervical headgear and fixed appliance. Methods: Plaster study casts of 20 patients treated with cervical headgear without dental extractions were 3D-scanned and evaluated in three distinct times: initial (T1), immediate post-treatment (T2) and long-term retention (T3 - minimum 20 years). Transversal teeth distance of maxillary and mandibular canines, premolars and first molars were measured. Results: A statistically significant increase during treatment was observed for all maxillary teeth transversal distances (p< 0.05). In turn, a significant reduction was observed in the long term (p< 0.05). For the mandibular teeth, canine transversal distance presented statistically significant constriction in the retention period (p< 0.05). Mandibular first molars distance was significantly expanded by treatment (p< 0.05) and remained stable in the long term. The changes observed for the other teeth or other times were considered not statistically relevant. Conclusions: For the accessed sample, transversal changes occurred during treatment and retention phases in Class II division 1 patients treated with cervical headgear and fixed appliance. Relapse was considered statistically relevant, even with the institution of a retention protocol.

Sensitivity analysis for periodic orbits and quasiperiodic invariant tori using the adjoint method

&lt;p style='text-indent:20px;'&gt;This paper presents a rigorous framework for the continuation of solutions to nonlinear constraints and the simultaneous analysis of the sensitivities of test functions to constraint violations at each solution point using an adjoint-based approach. By the linearity of a problem Lagrangian in the associated Lagrange multipliers, the formalism is shown to be directly amenable to analysis using the COCO software package, specifically its paradigm for staged problem construction. The general theory is illustrated in the context of algebraic equations and boundary-value problems, with emphasis on periodic orbits in smooth and hybrid dynamical systems, and quasiperiodic invariant tori of flows. In the latter case, normal hyperbolicity is used to prove the existence of continuous solutions to the adjoint conditions associated with the sensitivities of the orbital periods to parameter perturbations and constraint violations, even though the linearization of the governing boundary-value problem lacks a bounded inverse, as required by the general theory. An assumption of transversal stability then implies that these solutions predict the asymptotic phases of trajectories based at initial conditions perturbed away from the torus. Example COCO code is used to illustrate the minimal additional investment in setup costs required to append sensitivity analysis to regular parameter continuation. &lt;b&gt;200&lt;/b&gt; words.&lt;/p&gt;

RF system challenges for future hbox {e}^+ hbox {e}^- circular colliders

The RF system is the centrepiece of any future circular lepton collider. In particular, the system is required to support the high intensity beams needed for pushing the luminosity at the lower energy regimes of future energy-frontier circular lepton colliders (e.g. for operation in the Z peak and at the WW threshold). Capturing, storing the beam and replacing energy losses from synchrotron radiation demand low frequency, low shunt resistance cavities, low number of cells and high RF power per cell. Controlling the beam both transversely and longitudinally requires sophisticated beam control and timing systems. Additional RF systems are used to ensure transverse stability (feedback systems) and to increase the luminosity (crab cavities). Operation at high energies (such as the ZH and {mathrm{t}{overline{mathrm{t}}}} threshold) requires a very large accelerating voltage, since synchrotron radiation leads to significantly higher energy losses per turn which must be compensated. Since the RF system is to be optimised in size and energy efficiency for varying demands for the different operational modes, the spectrum of R &D challenges covers a wide range of technologies.

Vibration and dynamic analysis of a cantilever sandwich microbeam integrated with piezoelectric layers based on strain gradient theory and surface effects

In this paper, size-dependent vibration and dynamic analysis of an advanced sandwich composite microbeam including piezoelectric layers based on higher-order strain gradient and surface effects theories are investigated. To evaluate and analyze the effect of surface energy, length scale parameters and dynamic response on the transverse vibration and stability of sandwich smart composite microbeam with piezoelectric layers, the partial differential equation of motion is obtained using Hamilton's principle. Subsequently, this equation is transformed into a set of ordinary differential equations according to the generalized differential quadrature method. The influences of various material length scale associated with strain gradient theory, geometry and surface parameters such as thickness to material length scale parameter, surface residual stress, Young's modulus of surface layer, surface mass density and surface piezoelectric constant on structural dynamic deflection behavior and natural frequency have been investigated. In addition, the vibration and dynamic responses of the model were compared with those micro sandwich beams based on modified couple stress and classical theories. The obtained results are compared with the results available in the literature to validate the correctness of the present solution method. The results indicated that strain gradient theory with considering the surface effects increases the model stiffness and shifts the amplitudes to lower magnitude faster in comparison to other theories. Moreover, the influences of material length related to dilatation gradient on vibrational frequency are significant among the other parameters. Also, the free vibrational frequency increases with decreasing the length to thickness ratio.

Determining residuary resistance per unit weight of displacement with Symbolic Regression and Gradient Boosted Tree algorithms

Determining the residuary resistance per unit weight of displacement is one of the key factors in the design of vessels. In this paper, the authors utilize two novel methods – Symbolic Regression (SR) and Gradient Boosted Trees (GBT) to achieve a model which can be used to calculate the value of residuary resistance per unit weight, of displacement from the longitudinal position of the center of buoyancy, prismatic coefficient, length-displacement ratio, beam-draught ratio, length-beam ratio, and Froude number. This data is given as results of 308 experiments provided as a part of a publicly available dataset. The results are evaluated using the coefficient of determination (R2) and Mean Absolute Percentage Error (MAPE). Pre-processing, in the shape of correlation analysis combined with variable elimination and variable scaling, is applied to the dataset. The results show that while both methods achieve regression results, the result of regression of SR is relatively poor in comparison to GBT. Both methods provide slightly poorer, but comparable results to previous research focussing on the use of “black-box” methods, such as neural networks. The elimination of variables does not show a high influence on the modeling performance in the presented case, while variable scaling does achieve better results compared to the models trained with the non-scaled dataset.