Dynamics Simulation Procedure Research Articles

Analysis of multi-modal public transportation system performance under metro disruptions: A dynamic resilience assessment framework

The well-functioning multi-modal public transportation systems play crucial roles in reducing traffic congestion, alleviating environmental pollution, and improving mobility. There are variants of disruptions that may impede the smooth functioning of public transportation systems and challenge their normal operations. It is essential to develop resilient multi-modal public transportation systems, and a reasonable resilience assessment framework serves as the foundation for developing such systems. In this paper, we propose a resilience assessment framework based on performance-based measurement metrics. We develop a dynamic simulation procedure that considers the impacts of disruptions on passenger choices of path and departure time. By incorporating these features into the simulation procedure, we can effectively model the variations of passenger flow under disruptions. Finally, to demonstrate the proposed resilience assessment framework and dynamic simulation procedure, the multi-modal public transportation system in Beijing is considered as a case study. The results reveal that the system exhibits good resistance and recovery capabilities, but it lacks robustness. Additionally, we discuss the effects of downtime, bus frequency, bus bridging services, and proportions of commuters on resilience, which lead to several valuable policy implications.

The effect of number of nanoparticles on atomic behavior and aggregation of CuO/water nanofluid flow in microchannels using molecular dynamics simulation

A nanofluid (NF) is a mixture of metallic or non-metallic nanoparticles (NPs) suspended in a fluid. The high activity and energy of the surface atoms of NPs cause them to stick together and aggregate in the base fluid (BF). This leads to instability, changes in the NF concentration, and fouling and obstruction of the flow path, which reduces the NF's thermal conductivity (TC). In this study, the effect of copper oxide NPs on atomic behavior and the aggregation procedure in a water/CuO NF flow in a microchannel was explained using a Molecular Dynamics (MD) simulation procedure. For this purpose, various physical parameters, such as density, temperature, velocity, aggregation time (AT), and potential energy (PE), were calculated. The resultsshowthat after 1 ns, the temperature and PE converged to 300 K and −553088 eV. By CuO NPs number increasing among H2O molecules, the maximum ratio of density, temperature, and V profiles reached 1.60 g/cm3, 0.0122 Å/ps, and 303 values. The aggregation process in simulated NF was varied by these atomic changes. From a numerical point of view, by CuO NPs number increasing from 2 to 3 NPs, the AT reduced by 1.15 ns to 1.01 ns. Furthermore, this atomic evolution was investigated by PE changed from −652411 to −660258 eV.

Dynamic simulation of a triple-mode multi-generation system assisted by heat recovery and solar energy storage modules: Techno-economic optimization using machine learning approaches

Intelligent design and operation optimization allow energy systems to take advantage of the flexibility that multi-generation provides. This study proposes a basic solar-driven system integrated with thermal energy storage for round-the-clock energy harvesting. A modified configuration is then designed incorporating innovative multi-heat recovery approaches to increase the capacity and product diversity of the basic system. The modified system is able to cover vital urban utilities such as electricity, fresh water, cooling, and hydrogen throughout the day. To overcome the time-consuming procedure of dynamic techno-economic simulation as well as the limitation of commercial engineering equation solvers for tri-objective optimization, a deep learning approach is developed to reduce the computational complexity and improve the analysis accuracy. In this regard, the trained neural networks play an intermediary role in coupling the developed code with the MATLAB optimization toolbox. A comparison between the modified and conventional configurations indicates that implementing the multi-heat recovery approach results in a 29% increase in power generation while only increasing the overall system cost by 1.97%. From an economic perspective, the Sankey diagram depicts that the storage unit with a cost rate of 12.25 $/h accounts for 6.77% of the plant's cost rate, which enables the system to operate continuously. According to the sensitivity analysis and contour plots, the number of collectors significantly affects the total cost rate and fresh water production capacity while it has no tangible effect on the exergy efficiency.

Probabilistic impact fragility analysis of bridges under Barge collision and local scour

Vessel collision is a common cause of structural failure to bridges crossing navigable waterways. Although numerous efforts focus on the safety evaluation of bridge structures under vessel impact, very few jointly consider a more threatening situation that involves a scoured bridge colliding with a vessel (e.g., a barge). In this work, an impact fragility analysis (IFA) process is proposed to understand a bridge's failure probability under the combined hazards. To achieve high-fidelity modeling of material behavior during the collision process, scaled pier-foundation models subjected to pendulum impacts are experimentally studied. Nonlinear material models and an explicit dynamic simulation procedure are verified, which are further adopted to develop a high-resolution finite-element model for a full-scale three-span bridge. The resulting impact-fragility models conditional upon impact velocities at different scour depths reveal essential insights into the failure modes of the bridge. The findings include that: (1) scour has a minor effect on the probability of slight and moderate damage at various impact velocities; (2) at a high impact velocity (when higher than an impact fragility velocity threshold), scour can significantly increase the probability of major damage and collapse; (3) barge-tonnage has a significant influence on the threshold value reflecting the significant scour effects.

Comparative antibacterial analysis of the anthraquinone compounds based on the AIM theory, molecular docking, and dynamics simulation analysis.

Hydroxyanthraquinones and anthraquinone glucoside derivatives are always considered as the active antibacterial components. Comparison of structure characteristics and antibacterial effect of these compounds was performed by applying quantum chemical calculations, atoms in molecules theory, molecular docking, and dynamics simulation procedure. Density functional theory calculation with B3LYP using 6-31G (d, p) basis set has been used to determine ground state molecular geometries. The molecular geometric stability, electrostatic potential, frontier orbital energies, and topological properties were analyzed at the active site. Once glucose ring is introduced into the hydroxyanthraquinone rings, almost all of the positive molecular potentials are distributed among the hydroxyl hydrogen atoms of the glucose rings. In addition, low electron density ρ (r) and positive Laplacian value of the O-H bond of the anthraquinone glucoside are the evidences of the highly polarized and covalently decreased bonding interactions. The anthraquinone glucoside compounds have generally higher intermolecular binding energies than the corresponding aglycones due to the strong interaction between the glucose rings and the surrounding amino acids. Molecular dynamics simulations further explored the stability and dynamic behavior of the anthraquinone compound and protein complexes through RMSD, RMSF, SASA, and Rg. The type of carboxyl, hydroxyl, and hydroxymethyl groups on phenyl ring and the substituent glucose rings is important to the interactions with the topoisomerase type II enzyme DNA gyrase B.

Phase change process in a porous Carbon-Paraffin matrix with different volume fractions of copper oxide Nanoparticles: A molecular dynamics study

In this study, the phase transition process of porous carbon matrix (PCM) containing paraffin as phase change materials (PCM) in copper oxide nanoparticles (NPs) is explored utilizing the molecular dynamics (MD) simulation procedure. PCMs can cumulate and disseminate huge energy due to their high melting heat. In this way, the changes in the charge time, discharge time, heat flux (HF), and phase transition time are studied. The effects of the nanoparticles percentage and the initial temperature (T) on the thermal manner of the atomic sample are studied. The nanoparticle's atomic percentage from 1 % to 5 % enhanced the HF from 1452 to 1726 W/m2 and decreased the phase transition time from 3.92 to 3.05 ns. So, the thermal manner of the atomic matrix progressed by increasing the percentage of nanoparticles, and phase transition occurred in a brief time. The initial T from 300 to 350 K enhanced the HF from 1452 to 1770 W/m2 and reduced the phase transition time from 3.92 to 3.73 ns.

How Does Income Heterogeneity Affect Future Perspectives on Food Consumption? Empirical Evidence from Urban China.

China is undergoing a rapid dietary transition as well as a changing income distribution. In this paper, we examine the impacts of income heterogeneity on the prediction of food consumption using a dataset that covered 22,210 urban households in China’s 6 provinces. The two-stage Exact Affine Stone Index Implicit Marshallian Demand System (EASI demand system) model, which deals with the problem of censoring and endogeneity, is applied to estimate demand elasticity across income strata. Additionally, a dynamic simulation method considering income heterogeneity is conducted to predict future food consumption trends. The results reveal that income elasticity follows a decreasing trend with income growth. Furthermore, the results show that the consumption of major food items in the 15th period will increase by 7.9% to 42.0% over the base period. The growth potential of low-income groups is significantly higher than that of middle- and high-income groups. However, the prediction results may be overestimated if the differences in consumer behavior across income groups and the dynamic simulation procedure are not taken into account. Our study indicates that the consumption features of different income groups need to be included in food consumption forecasts. Moreover, the government should formulate food policies for different income groups to promote a sustainable food system transformation.

Wind-induced vibration assessment of tower cranes attached to high-rise buildings under construction

When attached to slender super high-rise buildings, tower cranes are facing increasing risk of failure under extreme wind scenarios. To take an insight into such wind-induced vibration safety concern, some specifically customized computational fluid dynamics (CFD) modelling and simulation procedures are proposed to address the spatio-temporal feature of in-construction buildings and various working conditions of tower cranes. Based on a variety of CFD simulations, the shape coefficients of main building are determined for various construction scenarios. The dynamic response of a crane is analyzed by wind pressure history applied directly on its surface and the excitations at the supports transferred from main building. The construction stage, the uncertainties of predicted wind velocity, as well as overloading and connection stiffness, are included in the response simulation of the tower crane. All the possible failure scenarios can be well simulated by the proposed procedures combined with rational determination of related parameters.

Evaluation of Radiation Resistance of Polystyrene Using Molecular Dynamics Simulation

The scission rates of polystyrene and fluorinated polystyrene irradiated in an irradiation facility with Co-60 γ-rays were determined using molecular dynamics simulation and gel permeation chromatography (GPC) molecular weight distributions. The prediction was based on the assumption that γ-ray energy is transferred to the initial velocity of the primary knock-on atom. We employed a molecular dynamics simulation procedure to compute the changes in bond length between the connections for selected values of the absorbed dose and compared the calculated values with measurements made on the irradiated samples. The samples were exposed to four different absorbed doses of 25, 50, 75, and 100 kGy. The scission process and scission ratio were simulated with LAMMPS with ReaxFF potential for each bond, and we compared the simulation results with the experimental data especially measuring average molecular weight to evaluate the effect of fluorination on radiation enhancement.

Synthesis of (Z)-3-((5-(benzylthio)-4H-1,2,4-triazol-3-yl)imino)-5-haloindolin-2-one derivatives: combined spectroscopic and computational investigations on the level and activity of matrix metalloproteinases 2 and 9 in cancer cell lines

Angiogenesis is an essential factor for cancer progression. Although more attention is paid in angiogenesis on its role in cancer biology, many other non-neoplastic diseases are also angiogenic-dependent. Recently, there is motivation to control cancer via inhibition of angiogenesis. Isatin-based scaffolds have been extensively used as anticancer agents in the recent years. Although some biological properties of isatin-based scaffolds are determined, their effects on angiogenesis are rare. So, we investigated the antiangiogenic effects of isatin-1,2,4-triazole conjugates. (Z)-3-((5-(benzylthio)-4H-1,2,4-triazol-3-yl)imino)-5-haloindolin-2-one macromolecules 1a–1l were synthesized and characterized, and the buffered solutions were used for evaluation of their cytotoxicity (cell viability) by MTT assay in vitro against U87MG (human glioblastoma astrocytoma) and A2780 (human ovarian carcinoma) cancer cell lines. Also, the effects of the compounds 1a–1l on supernatants activities and levels of matrix metalloproteinases (MMP-2 and MMP-9) were assayed using enzyme-linked immunosorbent assay (ELISA) and gelatin zymography. The compounds 1j–1l have the greatest cytotoxicity against studied cell lines. Moreover, our observations indicated that 1j–1l decreased the supernatants activity of MMP-2 and MMP-9 more than the others and all of the tested compounds considerably decreased the supernatant levels of MMP-9. The molecular mechanism of 1j binding to MMP-2 and MMP-9 was investigated by fluorescence quenching, absorption spectroscopy, FT-IR, molecular docking and molecular dynamics (MD) simulation procedures.

Dynamic simulation of distribution networks using multi-stage discontinuous Galerkin method

Dynamic simulation acts a fundamental role in security evaluation of distribution networks(DNs). However, the strong stiffness and non-linearity of distributed generation(DG) models in DNs bring about burdensome computation and noteworthy instability on traditional methods which hampers the rapid response of simulation tool. Thus, a novel L-stable approximate analytical method with high accuracy is proposed to handle these problems. The method, which is referred to as multi-stage discontinuous Galerkin method(MDGM), first derives approximate analytical solutions(AASs) of state variables which are explicit symbolic expressions concerning system states. Then, in each time window, it substitutes values for symbolic variables and trajectories of state variables are obtained subsequently. This paper applies MDGM to DG models to derive AASs. Local-truncation-error-based variable step size strategy is also developed to further improve simulation efficiency. In addition, this paper establishes detailed MDGM-based dynamic simulation procedure. From case studies on a numerical problem, a modified 33-bus system and a practical large-scale DN, the proposed method demonstrates fast and dependable performance compared with the traditional trapezoidal method.

Wettability of Primer-Treated Al2O3 Surfaces by Bisphenol A Diglycidyl Ether: Determination of the Mechanism from Molecular Dynamics Simulations and Experiments.

This study aims to develop a molecular dynamics (MD) simulation procedure to investigate the wettability of primer-treated Al2O3 surfaces by bisphenol A diglycidyl ether (BADGE) and to understand the interaction between the surface and the liquid. The MD simulation results were compared with those obtained by contact angle measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and atomic force microscopy (AFM) and were found to be in agreement with the experimental evaluations. The results obtained from both the MD simulations and the experiments suggest that the configuration of the primers on the surface affect its wettability. In other words, silanes lying flat on the surface, such as mercapto silane, make it easy for BADGE to access any polar functional groups of the silane, thereby leading to a strong interaction and good wettability. For amino silane, although the configuration is similar to that of mercapto silane, its amino groups are bound to the surface owing to their high polarity, which results in a reduced accessibility for BADGE and a relatively poor wettability in comparison with mercapto silane. On the contrary, for silanes that stand up on the surface, including trifluoroalkyl silane, BADGE is hindered from approaching the silanol groups and interacting with them, and the surface shows poor wettability.

Determination of time dependent stress distribution on a potato tuber during drop case

AbstractRealistic representation of time‐dependent internal stress progression and deformation behavior of a potato tuber during a sample drop case has been studied in this article. A reverse engineering approach, compressive tests, slow motion camera records and finite element analysis (FEA) were employed to analyze the drop case deformation behavior of a sample potato tuber. Simulation results provided useful numerical data and stress distribution visuals. The numerical results are presented in a format that can be used for the determination of bruise susceptibility magnitude on solid‐like agricultural products during drop case. The visual observations revealed that slow motion camera images and simulation printouts were in good correlation. The modulus of elasticity of the potato specimens was calculated from experimental data to be 3.12 MPa and simulation results showed that the maximum equivalent stress was 0.526 MPa on the tuber. This value for stress indicates that bruising is not likely on the tuber under a pre‐defined drop height. In order to test the simulation accuracy, empirical, and simulation‐based estimates for total energy in this drop case were compared. The relative difference between empirical and simulation results was 1.27%. This study provide a good “how to do” guide to further research on the utilization of (FEM)‐based time‐dependent simulation approach in complex mechanical impact based damaging analyses and industry focused applications related to solid‐like agricultural products such as potato.Practical applicationsThe engineering simulation based “how to do” pathway presented in this study is a scientific novelty because the explicit dynamics simulation technique for potato tuber damage under drop case and its visual verification has been limitedly introduced in the literature. This study present deeper analysis on material model description, slow motion camera records, time dependent non‐linear stress analysis and FEM based Explicit Dynamics Simulation procedures. This study aims to represent a realistic non‐linear deformation case of the tuber which is very complicated to obtain through physical and/or empirical expressions. As a further step from other literature studies, this research has presented a novel realistic time‐dependent non‐linear drop test simulation based on physical compressive material test data. The findings have been prepared in a form which may be used as input parameters in design studies for solid‐like agricultural products (such as potato tubers) processing machinery systems used in food/agricultural industries.

Dynamics of flexible peptides under the action of an electrostatic field in the gas phase

The Ion Mobility Spectrometry data of flexible peptides have been found to depend on the temperature of the buffer gas. It has been observed that the number of the peaks of the arrival time distribution may vary, while the position of the peaks may shift with temperature. Such changes depend on the emerging conformers at the experimental conditions. The motion and the dynamics of the peptide are reproduced here through a Nonequilibrium Molecular Dynamics Simulation procedure that depends on the structure of the bending macromolecule. A specific molecular model of one bending mode is considered that depends on an angular interaction potential. The observed conformations are introduced through the consideration of local minima in the model potential. As the molecular dynamics simulation proceeds, the population of the metastable structures is changing in time due to energy exchange during the ion-atom interactions. The corresponding angle distributions depend on the temperature and the field strength. We find that the observed motion of the peptide conformers can be reproduced accurately with the use of empirical model potentials and further predict the behavior of the ions at strong electric fields. The procedure can produce mean properties, such as the ion velocity and energy, as well as molecular distributions and dynamic properties, such as velocity correlation functions. We expect the method to apply to similar flexible macromolecules that acquire one bending mode.

Explicit dynamics simulation of Pecan fruit deformation under compressive loading-Part-2: Explicit dynamics simulation procedure

This study, which is divided into two parts, introduces an explicit dynamics simulation procedure for Pecan fruit (Carya illinoinensis) deformation under compressive loading. This second part of the study covers a microstructure investigation for the inner structure of the Pecan fruit components, discussions on the material models used in FEM-based simulation, and the explicit dynamics simulation procedures. An application algorithm based on experimental and theoretical methods is described in the study. Visual understanding and/or presenting a detailed description of the deformation behavior/characteristics for agricultural products through analytical calculations or/and physical experiments is a complicated phenomenon. Most especially, this phenomenon becomes more complicated for shelled edible agricultural products under varying loading cases. Numerical method based advanced engineering simulation techniques may be useful for a deeper visual understanding of agricultural product deformation behavior/characteristics. A major focus of the second part of the study detailed in this paper is finite element method (FEM) based explicit dynamics simulation procedures and the realistic representation of time dependant nonlinear deformation of Pecan fruit (kernel-in-shell) under a two plate compression loading case. Simulation results pointed out that the maximum equivalent stress values were 18.10, 11.50, and 1.14 MPa for whole Pecan fruit (kernel-in-shell), the shell and the kernel respectively. The stress values on the kernel were beyond the defined damage point of the kernel material (0.380 MPa). This indicated a permanent deformation/damage on the kernel at the end of the defined compression case. This study contributes to further research into the utilization of nonlinear explicit dynamics based deformation simulation studies for shelled edible agricultural products. Practical applications The simulation approach and application algorithm introduced in this two-part study is a scientific novelty because the explicit dynamics simulation approach for Pecan fruit deformation has not been previously reported in the literature. This second part introduces deeper investigations on material model description, microstructure investigation and FEM-based explicit dynamics simulation procedures. This simulation aims to represent a realistic nonlinear deformation case of the fruit which is very difficult to obtain through experimental and/or mathematical expressions. As a further step from other researchers, this study has introduced a novel realistic time-dependant nonlinear deformation simulation study based on experimental data. The findings have been presented in a form which may be used as input parameters in design studies for shelled agricultural product processing machinery systems used in related industries.

Explicit dynamics simulation of Pecan fruit deformation under compressive loading—Part‐1: Determination of modulus of elasticity

AbstractThis study, which is divided into two parts, introduces an explicit dynamics simulation procedure for Pecan fruit (Carya illinoinensis) deformation under compressive loading. An original application algorithm based on experimental and theoretical methods has been described in the study. The major aim of this Part 1 is to determine the modulus of elasticity through various calculation approaches for Pecan fruit. In addition to this, some engineering properties of the Pecan fruit components were determined to define them as simulation input parameters in an explicit dynamics deformation simulation which is detailed in the second part of the study. The original geometry of the Pecan fruit and its components were digitized using reverse engineering technology (three‐dimensional [3D] laser scanning). Force–deformation data, which can describe the physical deformation characteristics of the Pecan fruit components, was collected through experimental compression tests. Initial crack points for the Pecan shell (kernel‐in‐shell) in these tests were measured as 335.62, 239.42, and 165.03 N for longitudinal, transverse, and suture orientations, respectively. Hooke's, Hertz's, and Boussinesq's theories and finite element method simulation based linear prediction approach based modulus of elasticity calculations were realized. Results from these calculations revealed that loading orientation is an important factor and there were differences between the results of calculation theories (15.2% on average).Practical applicationsThe simulation approach and application algorithm introduced in this two‐part study is a scientific novelty because the explicit dynamics simulation approach for Pecan fruit deformation has not previously been reported in the literature. This first part focuses on realistic description (digitizing) of the fruit geometry through a reverse engineering approach and determination of modulus of elasticity (by considering various theories) and some engineering properties of the Pecan fruit components (experimentally). These investigations have important roles in this study so that realistic material models of the fruit components can be described in the simulation study which is presented and detailed in the second part of the study. In this part, it has been experienced that loading orientation is an effective factor for fruit deformation behavior and different theories may provide different results during calculation of the specific mechanical properties. These important findings have been presented in a form which may be used as input parameters in design studies of shelled agricultural product processing machinery systems used in the related industry.

Dynamic simulation of a multicomponent distillation column for D-T separation

Cryogenic distillation (CD) process is being employed, among other applications, in tritium separation technologies and in case of ITER is one of the key processes in the fuel cycle. The ITER Isotope Separation System has to process by cryogenic distillation various mixtures of H-D-T depending from the various torus operation scenarios.Cryogenic distillation has also been employed to separate and concentrate tritium in a CANDU water detritiation system. Dynamic simulation of a distillation column gives information on the behavior of the system when fluctuations in flow feed or feed concentration may occur, with direct impact on the design of the control system.The objective of this work is to present a mathematical model for dynamic simulation of a multicomponent distillation column for D-T separation. The procedure of dynamic simulation is based on Lewis – Matheson method and tridiagonal matrix method for design, respectively simulate a multicomponent distillation column for D-T separation; the model is used to determinate the time required to reach steady state into the entire distillation column, after the occurrence of a process perturbation (e.g. modification of a feed flow, feed concentrations).

Computational fluid dynamics simulation and statistical procedure for estimating wide-area distributions of airborne sea salt considering local ground conditions

Steel corrosion under atmospheric conditions is a critical issue in the maintenance of structures such as electric transmission towers and bridges during their long-term operation, which are generally located at many places over a wide area. Since a major factor causing corrosion is airborne salt particles coming from the sea, wide-area distributions of the long-term cumulative amount of sea salt deposited on surfaces are needed. Moreover, since the amount of airborne sea salt varies locally with the topography, it is also important to consider the effects of topography. In this paper, a method combining a computational fluid dynamics model and a statistical procedure is proposed to efficiently estimate wide-area distributions of the cumulative amount of airborne sea salt by considering the local topography. The predicted amount of airborne sea salt decreases with increasing distance from the coast and varies with the topography and the offshore wind. A comparison between predicted and observed amounts revealed that: (1) this method appropriately estimates topographical effects on sea-salt transport and enables the estimation of deposited sea salt on structure surfaces, and (2) consideration of the trapping efficiency of sea-salt particles on structure surfaces improves the prediction accuracy.

Mathematical modeling and optimization of cam mechanism in delivery system of an offset press

This paper presents a new method for cam profile design and optimization by integrating a single objective optimization procedure with a dynamic model of cam-follower mechanism in delivery system of an offset press. The proposed approach based on a new strategy mainly includes two parts, a single objective optimization procedure for the kinematic characteristics of the follower and a dynamic model for the cam-follower mechanism. For the first part, the follower acceleration profile is described by modified trapezoidal curve, thereby deriving the velocity, jerk and displacement functions, respectively. Then sequential quadratic programming (SQP), which deals well with equality and inequality constrains, is adopted as the single objective optimized algorithm in this part. In the second part, a two degrees of freedom lumped parameter model taking into account the torsional flexibility and damping of the grippers, the contact compliance at the cam/roller and grippers/block interfaces, is established to investigate the dynamic behavior of the force-closed cam-follower mechanism. In order to improve the kinematic and dynamic characteristics of cam-follower mechanism synthetically, an optimization cycle, known as iterative process, is introduced to implement the procedure of single objective optimization and dynamic simulation alternately. The example illustrated in this paper, sufficiently demonstrates the effectiveness of the new method. Ultimately, the proposed approach gives cam designers a useful tool to design and optimize the cam profile, so as to reduce residual vibration.

Structural Dynamics of the Vimentin Coiled-coil Contact Regions Involved in Filament Assembly as Revealed by Hydrogen-Deuterium Exchange

Intermediate filaments (IF) are major constituents of the cytoskeleton of metazoan cells. They are not only responsible for the mechanical properties but also for various physiological activities in different cells and tissues. The building blocks of IFs are extended coiled-coil-forming proteins exhibiting a characteristic central α-helical domain ("rod"). The fundamental principles of the filament assembly mechanism and the network formation have been widely elucidated for the cytoplasmic IF protein vimentin. Also, a comprehensive structural model for the tetrameric complex of vimentin has been obtained by X-ray crystallography in combination with various biochemical and biophysical techniques. To extend these static data and to investigate the dynamic properties of the full-length proteins in solution during the various assembly steps, we analyzed the patterns of hydrogen-deuterium exchange in vimentin and in four variants carrying point mutations in the IF consensus motifs present at either end of the α-helical rod that cause an assembly arrest at the unit-length filament (ULF) stage. The results yielded unique insights into the structural properties of subdomains within the full-length vimentin, in particular in regions of contact in α-helical and linker segments that stabilize different oligomeric forms such as tetramers, ULFs, and mature filaments. Moreover, hydrogen-deuterium exchange analysis of the point-mutated variants directly demonstrated the active role of the IF consensus motifs in the oligomerization mechanism of tetramers during ULF formation. Ultimately, using molecular dynamics simulation procedures, we provide a structural model for the subdomain-mediated tetramer/tetramer interaction via "cross-coiling" as the first step of the assembly process.