A data-driven microscopic on-ramp model based on macroscopic network flows

While macroscopic traffic flow models consider traffic as a fluid, microscopic traffic flow models describe the dynamics of individual vehicles. Capturing macroscopic traffic phenomena remains a challenge for microscopic models, especially in complex road sections such as on-ramps. In this paper, we propose a microscopic model for on-ramps derived from a macroscopic network flow model calibrated to real traffic data. The microscopic flow-based model requires additional assumptions regarding the acceleration and the merging behavior on the on-ramp to maintain consistency with the mean speeds, traffic flow and density predicted by the macroscopic model. To evaluate the model's performance, we conduct traffic simulations assessing speeds, accelerations, lane change positions, and risky behavior. Our results show that, although the proposed model may not fully capture all traffic phenomena of on-ramps accurately, it performs better than the Intelligent Driver Model (IDM) in most evaluated aspects. While the IDM is almost completely free of conflicts, the proposed model evokes a realistic amount and severity of conflicts and can therefore be used for safety analysis.Comment: 15 pages, 5 figure

A disulfide bridge in the calcium binding site of a polyester hydrolase increases its thermal stability and activity against polyethylene terephthalate

Elevated reaction temperatures are crucial for the efficient enzymatic degradation of polyethylene terephthalate (PET). A disulfide bridge was introduced to the polyester hydrolase TfCut2 to substitute its calcium binding site. The melting point of the resulting variant increased to 94.7°C (wild-type TfCut2: 69.8 °C) and its half-inactivation temperature to 84.6 °C (TfCut2: 67.3 °C). The variant D204C-E253C-D174R obtained by introducing further mutations at vicinal residues showed a temperature optimum between 75 and 80 °C compared to 65 and 70 °C of the wild-type enzyme. The variant caused a weight loss of PET films of 25.0 +/- 0.8% (TfCut2: 0.3 +/-0.1%) at 70 °C after a reaction time of 48 h. The results demonstrate that a highly efficient and calcium-independent thermostable polyester hydrolase can be obtained by replacing its calcium binding site with a disulfide bridge

Effect of Tris, MOPS, and phosphate buffers on the hydrolysis of polyethylene terephthalate films by polyester hydrolases

The enzymatic degradation of polyethylene terephthalate (PET) occurs at mild reaction conditions and may find applications in environmentally friendly plastic waste recycling processes. The hydrolytic activity of the homologous polyester hydrolases LC cutinase (LCC) from a compost metagenome and TfCut2 from Thermobifida fusca KW3 against PET films was strongly influenced by the reaction medium buffers tris(hydroxymethyl)aminomethane (Tris), 3-(N-morpholino)propanesulfonic acid (MOPS), and sodium phosphate. LCC showed the highest initial hydrolysis rate of PET films in 0.2 M Tris, while the rate of TfCut2 was 2.1-fold lower at this buffer concentration. At a Tris concentration of 1 M, the hydrolysis rate of LCC decreased by more than 90% and of TfCut2 by about 80%. In 0.2 M MOPS or sodium phosphate buffer, no significant differences in the maximum initial hydrolysis rates of PET films by both enzymes were detected. When the concentration of MOPS was increased to 1 M, the hydrolysis rate of LCC decreased by about 90%. The activity of TfCut2 remained low compared to the increasing hydrolysis rates observed at higher concentrations of sodium phosphate buffer. In contrast, the activity of LCC did not change at different concentrations of this buffer. An inhibition study suggested a competitive inhibition of TfCut2 and LCC by Tris and MOPS. Molecular docking showed that Tris and MOPS interfered with the binding of the polymeric substrate in a groove located at the protein surface. A comparison of the Ki values and the average binding energies indicated MOPS as the stronger inhibitor of the both enzymes

Study on pre-compaction of pavement graded gravels via imaging technologies, artificial intelligent and numerical simulations

Pavement compaction cannot be neglected during the motorway manufacture stage because it can determine pavement service quality and durability. Concerning the compaction scenario, the paving compaction is responsible for offering the preliminary strength of the pavement. Ignoring paving compaction quality control can lead to over compaction. This paper introduces an integral system to study and simulate the paving compaction of asphalt motorways in Discrete Element Model two-dimensional (DEM2D). This method includes the whole procedure from aggregate image acquisition database establishment to the DEM2D simulation of paving compaction. To this end, this study fulfils the creation of the aggregate database applied in DEM via the Aggregate Image Measuring System (AIMS) method. In addition, the artificial intelligent (AI) technology called Generative Adversarial Networks (GANs) method is proposed to expand the developed DEM aggregate database. Three different approaches are applied to calibrate the accuracy of the extended database. According to the aggregate database, the pavement paving compaction with different aggregate gradations can be simulated in DEM2D

Vom digitalen Zwilling zum digitalen Asset-Management

Der Digitale Zwilling Brücke unterstützt den Übergang von einer bisher reaktiven Erhaltung zu einem prädiktiven Lebenszyklusmanagement von Brücken. Damit wird das übergeordnete Ziel verfolgt, eine optimierte Unterstützung der Bauwerksbetreibenden bei der Gewährleistung der Sicherheit, Zuverlässigkeit und Verfügbarkeit zu leisten. Der digitale Zwilling eines Ingenieurbauwerks kann als ein digitales Abbild eines realen Bauwerks verstanden werden und spiegelt sämtliche Eigenschaften und sein Verhalten anhand verschiedener Modelle über dessen gesamten Lebenszyklus hinweg. Der digitale Zwilling aktualisiert sich kontinuierlich, um den aktuellen Status des realen Bauwerks sowie die daraus ableitbaren Prognosen möglichst zeitnah darzustellen. Zu diesem Zweck greift er auf große Datenmengen zurück, die u. a. am realen Bauwerk, dem Reallabor, gesammelt werden. Die Umsetzung des digitalen Zwillings für Brückenbauwerke ist aktuell Forschungsgegenstand, die Entwicklung einer Gesamtkonzeption für den Digitalen Zwilling Brücke und einzelner Komponenten steht aktuell im Fokus der BASt-Forschung. Hierbei sind die Anwendung von virtueller und erweiterter Realität in der Bauwerksprüfung, die KI-basierte (teil-)automatisierte Ableitung von Bestandsmodellen, und der Einsatz von KI-Verfahren zur Erkennung von Anomalien Beispiele für die Umsetzung einzelner Komponenten. Ein möglicher Einsatz des digitalen Zwillings kann über verschiedene Anwendungsfälle erfolgen, neben dem Themenbereich Erhaltungsplanung und -durchführung“ sind die Themenbereiche „Betriebsprozesse“ sowie „Strategisches Lebenszyklusmanagement“ von Relevanz. Für den Themenbereich „Erhaltungsplanung und -durchführung“ sind u. a. die Anwendungsfälle „Schadensanalyse“ und „Intervallbezogene Zustandserfassung“ von Bedeutung

Development of an FEM-DEM Model to Investigate Preliminary Compaction of Asphalt Pavements

Variations in pavement density have been widely monitored and investigated, both in laboratory and in field experiments, since the compaction of pavement is so critical to its long-term performance quality. In contrast to field testing, laboratory tests are simpler to produce but less accurate. Destructive drilled samples are used to conduct field testing; however, they are limited in their ability to assess density information at specific areas. The use of computationally aided approaches, such as the Finite Element Method (FEM) and the Discrete Element Method (DEM), in research involving asphalt mixtures is increasing, since these methods simulate and evaluate the characteristics of asphalt mixtures at macroscopic and microscopic scales. Individual particle behavior at the microscopic level cannot be fully represented using the FEM alone, and the computing cost of utilizing the DEM approach alone is prohibitively high. The objective of this work is to simulate the pre-compaction process by using the coupled FEM-DEM approach. In order to investigate the impact of the asphalt mixtures’ gradation, a dense-graded asphalt mixture (AC 11) and a gap graded asphalt mixture (PA 11) were simulated. Different paving speeds (4, 5, and 6 m/min) were applied on the preliminary compaction model of AC 11 to study the effect of the paving speeds on the compaction process. By comparing the angular velocity, which worked as a reference of compaction quality, it was demonstrated that the grade AC 11 asphalt mixtures performed better in the preliminary compaction process compared to the grade PA 11 asphalt mixtures. Moreover, since it has an effect on compaction, paving speed was carefully monitored and kept within a reasonable range in order to maximize both pavement quality and project efficiency

Numerical Simulation of Asphalt Compaction and Asphalt Performance

Asphalt pavement compaction is important, and it can determine the service quality as well as durability of pavement. In recent years, numerical methods have been extensively used to simulate and study the construction process of asphalt pavement and mechanical properties of asphalt mixtures. In the following sections, the compaction process, considering the interaction between the materials and the equipment, is simulated, and the influence of different compaction methods on the mechanical performance of asphalt mixtures is investigated. To achieve this goal, a pre-compaction model is developed using the Discrete Element Method (DEM), and the models of both materials and the paving machine are generated separately. After the pre-compaction simulation, the theory of bounding surface plasticity is combined with the theory of Finite Element Method (FEM) as well as with a kinematic model of a roller drum to simulate the asphalt mixture behavior during a roller pass. In order to ensure consistency both in the laboratory compaction and in-situ compaction, the Aachen compactor has been developed. The effect of different compaction methods (Field, Aachen and Marshall Compactions) on the asphalt specimens is compared and evaluated using the microscale FEM