Lateral Mode Research Articles

Pile group in clay subjected to cyclic lateral load: Numerical modelling and design recommendation

Major structures like offshore platforms, wind turbines, transport infrastructure, tall buildings, etc., resting on soft compressible clays, are often supported by pile foundations. Apart from usual vertical loading (dead load, live load, etc.), these piles are subjected to significant cyclic loads arising from actions of waves, ship impacts, winds or moving vehicles. Under such circumstances, the lateral mode of cyclic loading is predominant and affects the overall foundation stability. Such repetitive loading leads to stress reversal in adjacent soft clay initiating progressive degradation in soil strength and stiffness, deteriorating the pile capacity with unacceptable displacements. Although several past studies investigated the response of single pile under lateral cyclic loading, a detailed investigation on pile group in clay subjected to cyclic lateral loading, which is of immense practical interest to field engineers, is yet to be carried out. In this paper, in-depth study has been carried out by developing a three-dimensional dynamic finite element model. Comparison of the computed results with available test data validates the numerical model. Extensive parametric studies with field data indicate that both the axial and lateral pile capacities and displacements have been significantly influenced by the cyclic loading parameters. Relevant design curves are also constructed.

Lateral displacement mode of column-supported modular steel structures with semi-rigid connections

The lateral displacement of a column-supported modular steel structure with semi-rigid connections (CSMSS-SRC) owing to lateral loading was investigated to determine the corresponding lateral displacement mode and establish a foundation for a direct displacement-based seismic design method. Theoretical equations for the lateral displacement caused by the bending deformation of beams and columns, axial deformation of columns, and shear deformation of the vertical inter-module connections were theoretically derived using slope–deflection equations, unit-load method, and shear deformation definition, respectively. Two simplified single frame finite element models were then established to verify the theoretical equations and study the effects of the rotational and horizontal shear stiffnesses of the vertical inter-module connections on the lateral displacement of the CSMSS-SRC. The results showed that the proposed lateral displacement equations are highly accurate. Furthermore, although the rotational stiffness of the vertical inter-module connection did not exert an appreciable effect on the lateral displacement of the CSMSS-SRC, its horizontal shear stiffness did. These results are expected to provide a reference for the engineering design of CSMSS-SRC.

Seismic Analysis of Double Unit Tunnel Form Building Subjected to Out-of-Plane Lateral Cyclic Loading

Most of the high-rise buildings for commercial and residential purposes in Malaysia are constructed using a tunnel formwork system. This type of building becomes a favor due to the fast construction and cost-effectiveness. However, the research on the behavior of Tunnel Form Building (TFB) under the seismic effect is still insufficient and requires further investigation. Therefore, the safety level of double unit TFB subjected to weak plane (out-of-plane) was investigated in this study. The TFB was designed using a non-seismic provision to represent an existing condominium building constructed in Selangor. Ten past earthquake records categorized as major, moderate, and low magnitudes were utilized. The behavior of the double unit TFB was analyzed using the Ruaumoko 2D program. The ultimate lateral load, displacement, pseudo-spectral acceleration (PSA), pseudo-spectral displacement (PSD), and mode shape of TFB were also analyzed. Based on the findings, most of the selected earthquake records exceeded the lateral capacity of TFB. The building experienced a major damage under 6.9 Richter scale of Imperial Valley, 7.3 Richter scale of San Joaquin Valley, and 7.9 Richter scale of Denali Earthquakes excitations. Therefore, these findings suggested if any similar magnitudes of unpredicted seismic events would occur in the future, significant damages may be experienced by the existing TFB in Malaysia. Doi: 10.28991/CEJ-2022-08-11-012 Full Text: PDF

Nonlinear ensemble gray and black-box system identification of friction induced vibrations in slender rotating structures

Due to the nonlinear bit-rock and drill–string–borehole interactions, the modeling and analysis of drill string dynamics are a challenging work. These slender structures are subjected to torsional, lateral, and axial vibration modes, which are generally prejudicial to the drilling process. For this reason, proper modeling of the system dynamics is necessary to optimize drilling performance. In the present paper, we focus on the torsional dynamics and model of an experimental system subjected to friction torque. An ensemble approach, combining gray and black-box modeling techniques, is used to calibrate some of the dynamical system parameters, particularly those related to friction. This combination is chosen with the aim of improving the prediction accuracy of a pure gray-box approach while retaining interpretability in the dynamic responses. The present paper compares four well-known friction models with increasing levels of complexity using experimental data. It is shown that the ensemble model proposed can improve the gray-box by up to 92.68% in terms of prediction errors, by adding a non-physical layer to it. The present analysis demonstrates that better results can be obtained by using an ensemble of gray and black-box identification techniques for friction modeling and simulation, aiming at improving data-driven model construction of complex torsional dynamics in slender structures.

High-power distributed feedback lasers with high-order surface curved gratings.

A novel, to the best of our knowledge, broad-area distributed feedback laser with high-order surface curved gratings has been fabricated based on standard near ultraviolet lithography. The characteristics of increasing output power and mode selection are achieved simultaneously by using a broad-area ridge as well as an unstable cavity structure composed of curved gratings and a high-reflectivity coated rear facet. Suppression of high-order lateral modes is realized by setting current injection/non-injection regions and asymmetric waveguides. This DFB laser emitting around 1070 nm has achieved a spectral width of 0.138 nm and a maximum output power of 915 mW kink-free optical power. The threshold current and side-mode suppression ratio of the device are 370 mA and 33 dB, respectively. The simple manufacturing process and stable performance give this high-power laser broad application prospects in the fields of light detection and ranging, laser pumps, optical disk access, etc.

Quantitative evaluation method of smoke exhaust performance and application on exhaust volume optimization in tunnel fires under lateral centralized mode.

This study investigated the indicators in the quantitative method of evaluating the smoke exhaust performance, which provided a theoretical basis for the optimization of the smoke extraction system under the lateral centralized mode in tunnel fires. The criterion was proposed for plug-holing, and the theoretical models of smoke exhaust efficiency were established to distinguish whether the plug-holing occurs or not. The relationship between efficiency, effectiveness, and efficacy was analyzed from the perspective of smoke and heat exhaust. Meanwhile, this evaluation method was applied to the optimization of exhaust volume in a practical engineering through FDS numerical simulation. The results show that Ri is a vital basis for reflecting the movement form of smoke and the exhaust effect. The critical value of Ri is 1.09 when plug-holing occurs in a standard three-lane immersed tunnel, resulting in a significant reduction in the efficiency of smoke exhaust. The greater the exhaust volume of the exhaust fan, the greater the Ri value, the higher the total smoke and heat exhaust efficiency, and the better the exhaust effectiveness of smoke inlets without plug-holing. Under longitudinal ventilation, the optimal exhaust volume is 180 m3/s at 20MW and 360 m3/s at 50MW in the application case.

Earthquake Resistance Performance of a Multistorey RCC Frame Considering Two Different Positions of the Staircase

Abstract: The stairs have significant influence on the seismic lateral stiffness, vibration mode and internal force of frame beam column of the reinforced concrete frame structure. In this paper, 3 analysis models have been made by E-TABS. In these models, relevant analysis has been made about the influence of stairs in 10-storey building while it has no staircase, it is near the middle of the building and while it is near the corner of the building. Results from linear analysis show that in concrete structure, it is essential to consider the modelling of staircase as it causes additional stiffness and change in coordinate of center of rigidity. These effects can be evaluated in period, stiffness, base shear, lateral load and displacement of the structure.

Morphological risk factors for scaphoid fracture: a case–control study

PurposeMost patients with a clinically suspected scaphoid fracture and normal initial radiograph are unnecessarily treated. Previously developed prediction rules using demographic and clinical risk are unable to accurately predict occult fractures. Adding other risk factors could enhance this. Therefore, we aim to explore if there are morphological risk factors of the wrist for sustaining a scaphoid fracture.MethodsWe retrospectively included adult patients with a clinically suspected scaphoid fracture between 2013 and 2019 in our case–control study. There were 82 patients with a scaphoid fracture and 158 patients with a wrist contusion. Morphological risk factors were identified using statistical shape modelling (SSM) and linear measurements. Independent wrist shape variations on posteroanterior and lateral radiographs were captured in modes using SSM. Associations between outcomes and a scaphoid fracture were explored using logistic regression and the reliability was assessed.ResultsOf the 15 posteroanterior modes and 8 lateral modes identified and linear measurements performed, 1 PA mode was associated with a scaphoid fracture (PA mode 4; OR 1.40, CI 1.04–1.93, p = 0.031). We described this mode as an ulna plus and narrower distal radius with more volar tilt and radial inclination. The reliability of the posteroanterior modes and linear measurements was mostly good/excellent and moderate/poor for the lateral modes.ConclusionThere was one complex wrist shape significantly associated with a scaphoid fracture. Since the association was weak and the shape is difficult to identify radiographs, we believe this morphological risk factor would not enhance identifying occult scaphoid fractures in the future.

Modal sensitivity of three-dimensional planetary geared rotor systems to planet gear parameters

A parameter study is presented to determine effects of planet gear design parameters on the global modal behaviour of planetary geared rotor systems. The modal sensitivity analysis is conducted using a three-dimensional dynamic model of a planetary geared rotor system for the number of planet gears, planet mistuning, mass of planet gears, gear mesh stiffness and planet gear speed. These parameters have varying impacts on both natural frequencies and mode shapes, therefore the sensitivity of the planetary geared rotor vibration modes to the planet gear parameters is determined by computing the frequency shifts and comparing the mode shapes. The results show that the mass and mesh stiffness of planet gears have a larger influence on the global dynamic response. Torsional modes and coupled torsional-axial modes are more sensitive to gear mesh stiffness whereas lateral vibration modes are more sensitive to gearbox mass. Planet mistuning results in coupling between lateral and torsional vibrations. The planetary gearbox becomes more rigid in the torsional-axial modes and more flexible in the lateral modes with an increase in the number of planet gears. Planet gears are also found to be having significant gyroscopic effects inside the planetary gearbox. The main original findings in this study can be directly used as initial guidelines for planetary geared rotor design.

Fatigue damage analysis of pavements under autonomous truck tire passes

Abstract Two different tire configurations consisting of a dual tire and a super single wide tire having different range and distribution of contact pressures have been analyzed. Along with the effect of speed on development of pavement damage at speeds of 5, 50 and 80 km h−1 under zero and uniform wander modes. Results show that at super slow speeds of 5 km h−1, at dual wheel moving at zero wander mode, decrease in fatigue life of the pavement is 3.5 years, which is 1.45 times more than the dual wheel moving at uniform wander and 3.4 times more than wide tire moving at uniform wander mode. The difference between fatigue damage at different lateral wander modes is prominent at speeds greater than 50 km h−1. A wide tire performs better than the dual wheel under zero wander configurations.

Performance Analysis on the Small-Scale Reusable Launch Vehicle

According to the symmetrical characteristics of a new type of Reusable Launch Vehicle (RLV) in the recovery phase, we studied the basic aerodynamic model data of Starship and the aerodynamic data with rudder deflection, and the causes of its aerodynamic coefficients are expounded. At the same time, we analyzed its stability and maneuverability. According to the flying quality requirements, the lateral-directional model of Starship in the return phase at a high angle of attack is analyzed. Finally, we analyzed the lateral heading stability and control deviation of Starship by using the criterion and nonlinear open-loop simulations. The results show that the Starship has pitching and rolling stability, but it only has heading stability in some ranges of angle of attack, and there is no heading stability at a conventional large angle of attack. At the same time, after modal analysis and comparison of flight quality, it can be seen that the longitudinal long-period model of the starship degenerates into a real root and it is stable and convergent. The lateral heading roll mode is at level 2 flight quality, the helical mode is at level 1 flight quality, and the Dutch roll mode diverges, which needs to be stabilized and controlled later.

Effect of cerium-rich mischmetal content on the growth morphology and microstructure evolution of undercooled Al-70 wt%Si alloys

The Al-70 wt%Si alloys with various cerium-rich rare earth contents undercooled by electromagnetic levitation were investigated, and the nucleation and growth, growth mode, and morphology evolution of primary Si were observed and recorded using a high-speed camera and scanning electron microscope. When the undercooling is lower than ΔT1, primary Si is coarse long plates with specific edges and faces, showing a characteristic of the lateral growth mode. When undercooling approaches ΔT2, the recalescence interface becomes dendritic and massive, and dendritic primary Si covers the surface of the alloys. The growth mode of primary Si shows a mixed growth mode of lateral and non-lateral. When undercooling exceeds ΔT2, the recalescence interface takes on a parallel shape and the morphology of primary Si transforms to homogeneous and fine spherical shapes with smooth surfaces, indicating a characteristic of the non-lateral growth mode. With an increasing RE content, critical undercooling, ΔT1 and ΔT2, gradually decreases, with the lowest values of 78 and 180 K for an RE content of 1.5%.

Study on Stability of Anchored Slope under Static Load with Weak Interlayer

To study the stability characteristics of a rock slope with a weak interlayer, a test of the anchor frame slope was designed in this paper. The analysis model was established with FLAC3D, and the development law of safety factor, deformation, axial anchor force, soil pressure and maximum shear strain increment of the slope, and the supporting effect of frame anchor cable were obtained by grading loading. The research showed that the supporting effect of frame anchor cable support on the slope was remarkable, and the influence of slope vertical load on the slope safety factor was evident. The lateral deformation mode of the slope surface was large up and down, and minor in the middle. The weak intercalated layer blocked the internal diffusion of the settlement. The failure trend of slope was sliding along the weak interlayer and collapse occurred below the loading zone, and the final failure mode is wedge failure. The peak value of maximum shear strain increment was developed along the weak interlayer, and a shear strain mutation zone was formed inside the slope. It could be considered that the weak interlayer was the potential sliding surface of the slope.

Controlled vapor phase growth of germanium selenide and germanium microflakes

Graphene and transition metal dichalcogenides have been intensively investigated in recent years. Germanium selenide (GeSe) has emerged lately as a new low-symmetry two-dimensional material due to its extraordinary in-plane anisotropic electrical, optical, and optoelectronic properties. However, the controlled synthesis of large-scale GeSe flakes is still a significant challenge because of its strong interlayer coupling and low lattice symmetry. In this work, we have achieved the synthesis of rectangular GeSe microflakes (MFs) with lateral sizes up to 0.33 mm on the glass substrate via a vapor phase deposition technique. The lateral size, thickness, and growth mode of GeSe MFs can be effectively tuned based on space-confined and substrate engineering strategies. Germanium (Ge) MFs with triangular and hexagonal morphologies were simultaneously fabricated in the high-temperature zone. Our experimental results demonstrated that the growth temperature plays an important role in the selective growth of GeSe and Ge MFs. A corresponding growth mechanism has been discussed in detail based on systematic characterizations. Our work provides a new route for the controlled growth of large-size GeSe and Ge MFs, which promotes a promising future in the fields of novel optoelectronic devices.

Pile-soil interaction under cyclic lateral load in loose sand: Experimental and numerical evaluations

Pile foundations in loose sand are occasionally subjected to cyclic loading initiated by the influence of wind, wave, traffic loads, etc. Such load reversals alter the strength and stiffness of surrounding loose sand affecting the ultimate capacity and serviceability of the pile foundation. Although such cyclic loading may be under vertical, lateral or torsional modes or a combination, the lateral cyclic load dominates the other modes. To carry out an in-depth study on pile-soil interaction under lateral cyclic load in loose sand, a series of laboratory model tests were performed with 2 × 2 pile group, followed by developing two alternative numerical models, i.e., boundary element and finite element models (i.e., BEM and FEM). The BEM involved a p-multiplier technique to incorporate the group effect, while the FEM was developed by ABAQUS software incorporating 3D stress conditions. As observed, the BEM slightly over-predicts while the FEM marginally under-predicts the experimental observations. The lateral cyclic loading was found to produce stiffening effect on loose sand which increased the pile capacity and reduced the pile head displacement. Sand relative density is also found to affect the test and numerical results significantly. A set of important conclusions are drawn from the entire study.

Self-organisation phenomena in pedestrian counter flows and its modelling

We implement avoidance and following behaviour in a force-based model (AFFM) to develop realistic simulations of pedestrian counter flows. Using this innovative approach, we summarise an accelerate-then-decelerate lateral movement mode for pedestrians that minimised their required effort to avoid collisions with oncoming pedestrians travelling in the opposite direction. Then, we use the transfer entropy (TE) method to determine the spontaneous following behaviour of pedestrians to align their motion with a leading pedestrian moving towards the same destination. We also introduce a new parameter, lane entropy, to measure the motion smoothness of pedestrians and explain the quantitative characteristics of the lane formation phenomenon. The performance of the proposed model is compared with that of two other force-based models in terms of their ability to replicate the experimentally observed pedestrian flow patterns in a mock corridor, as designed by Feliciani and Nishinari in 2016. The results show that the AFFM performs well at reproducing microscopic behaviours observed in the experiments while consistently presenting the empirically observed lane formation phenomenon with quantitatively self-organised features (e.g., the order parameter and lane entropy). The proposed model is an efficient tool for future applications that can realistically model pedestrian counter flows under varying conditions.

The Hidden Flower in WS2 Flakes: A Combined Nanomechanical and Tip-Enhanced Raman Exploration.

We report on tungsten disulfide (WS2) flakes grown by chemical vapor deposition (CVD), which exhibit a flower-like surface structure above the primary few-layer flake with a triangular shape. The fine structure is only revealed in the mechanical, chemical, and electronic properties of the flake but not in the topography. The origin of this structure is the peculiar one-step growth during the CVD process that permits to control the sulfur concentration at any time. A high concentration of S at the onset of the deposition process leads to a rapid growth of the flake, resulting in tungsten vacancies. Reducing the sulfur concentration toward the end of the growth slows down the reaction and leads to sulfur vacancies. These microscale domains were studied by confocal- and tip-enhanced Raman spectroscopy revealing their chemical composition with high spatial resolution. A strong quenching of the photoluminescence in the tungsten-vacancy domains is observed. Atomic force microscope measurements, performed in intermittent contact mode, force modulation mode (including lateral force mode), and PeakForce quantitative nanomechanics mode, show that the mechanical properties of these domains differ. Within the tungsten-vacancy domains, the adhesion force is reduced, while the friction force increased. Kelvin probe force microscopy measurements show that the electronic properties of the flakes are modulated by these domains. The combined nanomechanical and nanospectroscopy measurements provide detailed insights on the inhomogeneous surface properties of the single WS2 flake, further highlighting how its multidomain properties can be finely tuned using CVD.

Sedimentary Architecture Analysis of Deltaic Sand Bodies Using Sequence Stratigraphy and Seismic Sedimentology: A Case Study of Jurassic Deposits in Zhetybay Oilfield, Mangeshrak Basin, Kazakhstan

Three-dimensional (3D) seismic data and well log data were used to investigate the sandstone architecture of the Middle Jurassic deltaic reservoirs of the Zhetybay Oilfield, Mangeshrak Basin, Kazakhstan. The base-level cycles of different scales were identified and divided using well log and 3D seismic data. Five types of sedimentary boundaries were identified in the mouth bar sandstones. The boundaries divide single mouth bars. Vertically, the spatial distribution of sand bodies can be divided into superposed, spliced, and isolation modes. Laterally, contact modes can be divided into superposition, lateral, and isolation modes. We found that the base-level cycle controls the evolution of the delta front sand body architecture. In the early decline or late rise of the base-level cycle, the superimposed or spliced modes dominate the sand body. By contrast, the lateral or isolation modes dominate the sand body in the late decline or early rise of the base-level cycle. This paper proposes an architecture model of the delta front sand bodies controlled by the base-level cycle. The spatial distribution and morphological variation of deltaic sand bodies could be linked to the base-level cycles.

Anisotropic Acoustodynamics in Gigahertz Piezoelectric Ultrasonic Transducers

In this work, we employed our newly developed optical imaging method to probe detailed acoustodynamic physics in gigahertz unreleased ultrasonic transducers based on an AlN-on-silicon system, revealing mode superposition, anisotropic transduction, and dynamic mode evolution. Superpositioned upon the dominant breathing mode along the vertical direction of the AlN layer, multiple resonant lateral modes are identified, and they are shown to evolve into a surface mode beyond the piezoelectric transduction envelope, with strong anisotropic transduction brought by the shear motion of silicon. This acoustodynamic property is important for verifying and further improving design theories of broadband piezoelectric transducers and thin film piezoelectric-on-substrate systems in general.

Frequency Domain Analysis of F-16 Aircraft in a Variety of Flight Conditions

Examining the flight quality of an aircraft to ensure the stability of the aircraft, increase maneuverability, and make the aircraft easier to control by the pilot necessitates an examination of the natural stability of the system. Within the scope of the paper, the frequency domain response of the F-16 aircraft dynamics is analyzed using Simulink models considering two different flight regimes because the frequency-domain methods have many distinct and important advantages over time-domain methods. Aerodynamic, propulsive, and atmospheric databases are used to create the nonlinear model. The trim analysis for cruise flights is carried out to obtain trim parameters. The aircraft is numerically linearized using the small perturbation theory. The linearized dynamics for each trim condition are used to create transfer functions for each input. The linear model is subsequently examined in the frequency domain to obtain information about the dynamic behavior of the aircraft, and flight quality analysis was examined by considering the lateral and longitudinal modes of the aircraft by international standards. It has been clearly understood the stability augmentation system design has critical importance for the modes with unstable or long steady-state duration.