Simulation Of Bridge Research Articles

Numerical simulation of thermal bridges in enclosure structures as an express-method for the expert assessment of thermal comfort in domestic premises

The paper presents the solution to the problem of numerical simulation of thermal comfort in domestic premises. Three thermal bridges have been selected as the key parameters for enclosure structures. They have been calculated on the basis of thermographic studies of a group of typical brick blocks of flats which are located in the city of Tyumen. The considered thermal bridges are as follows: the insulation connections in the outer wall openings; insulation in the outer wall corners; insulation in the outer wall-floor structure connections. The functional connections of the thermal comfort level versus the values of the thermal bridge parameters have been determined. The study has resulted in an express-method of the expert assessment of thermal comfort in domestic premises based on the total assessment of thermal bridges in enclosure structures. The method can be used for a complete structural survey of residential buildings, and in examination of building operation and heat-protective properties of enclosure structures.

Design and implementation of an Openflow SDN controller in NS-3 discrete-event network simulator

The NS-3 simulator comes with the Openflow protocol and a rudimentary controller for classic layer-2 bridge simulations. This controller lacks basic functionality provided by real SDN controllers, making it inadequate for experimentation in the scientific community. In this paper we propose a new controller with an architecture and functionality similar to that of full-fledge controllers yet simple, extensible and easy to modify - all characteristics specific to simulators.

Design and implementation of an Openflow SDN controller in NS-3 discrete-event network simulator

The NS-3 simulator comes with the Openflow protocol and a rudimentary controller for classic layer-2 bridge simulations. This controller lacks basic functionality provided by real SDN controllers, making it inadequate for experimentation in the scientific community. In this paper we propose a new controller with an architecture and functionality similar to that of full-fledge controllers yet simple, extensible and easy to modify - all characteristics specific to simulators.

Effects of seafarers’ emotion on human performance using bridge simulation

75–96% of maritime accidents are caused by human and organizational factors. Seafarers' emotion may degrade the effectivity of human behavior when tasks in onboard environment are complex and demanding. This study was concerned with the relationship between seafarers' emotion and occurring events in navigation. The Electroencephalogram (EEG) and Self-Assessment Manikin (SAM) scale rating are used to investigate the occurrence and impact of seafarers' emotions on their performance using a bridge simulator. The study was conducted and described in two sections: emotion calibration and test recognition. In the first section, two types of emotions are induced by the sound clips of the International Affective Digitized Sounds (IADS), developed by the National Institute of Mental Health Center for the Study of Human Emotions. In the second section, emotion is recognized by the Support Vector Machine (SVM) classifier, as well as self-rated after the crew-qualified test in a bridge simulator. The results indicate that SVM can identify the emotions by EEG feature extraction, with an accuracy of 77.55%. The results concerning officers' emotion in a bridge simulator test reveal that seafarers’ emotion in maritime operations, relating to events exposure, affects their behavior and decision-making. In addition, negative emotion has a higher likelihood of contributing to human errors than positive emotion. Less negative emotion is the most dangerous emotion state during navigation, followed by extreme positive emotion.

Assessing a maritime service website prototype in a ship bridge simulator: navigators\u2019 experiences and perceptions of novel e-Navigation solutions

The aim of this study was to assess proof of concept and usability of a maritime service website prototype in a full-mission ship bridge simulator through Swedish mariners’ experiences and perceptions. This test was part of the European Commission’s EfficienSea2 project for e-navigation. The prototype was intended as an aid to existing standard systems and methodologies for planning, executing and monitoring voyages. The study began with 5 days of simulator trials focused on today’s standard practices. This served as a baseline to compare to subsequent 4 days of simulator trials testing the prototype. For data collection, observations, video footage, interviews, and eye tracking were used. Data analysis included breaking apart the qualitative data to capture the perceptions of the participants, and a preliminary analysis of eye-tracking data as a complement. The results suggested that the prototype could be more suitable for a route planning stage, that the participants were familiar with similar existing solutions from other manufacturers, and that the contents of the tool would be most beneficial if integrated within the Electronic Chart Display and Information Systems (ECDIS). There is a pressing need for the novel solutions to be user needs-driven, integrated with the existing technologies, and standardized across the domain, and these processes must go hand-in-hand with accounting for all involved stakeholders, procedures, regulations, and training, as this will alter the course of shipping.

Frequency Co-integration-based damage detection for bridges under the influence of environmental temperature variation

Natural frequencies of structures are usually convenient to acquire with a high precision in engineering. However, it is still difficult and faces challenges to apply the frequencies in the area of structural health monitoring. One of the main reasons is the natural frequency’s sensitivity to the variation of environmental conditions, such as temperature, which often disturbs the frequency based identification and even results in the false evaluation of the structural health condition. To overcome this problem, a novel frequency-based co-integration technique is proposed in this paper. The main principle is that the non-stationarity of the acquired frequencies caused by the variation of environmental temperature, can be transformed to stationary sequence by linear combining two non-stationary frequencies using the co-integration algorithm. The calculated stationary relationship between two frequencies series is insensitive to the influence of environmental variation, and can be employed to detect structural damage. In the study, ADF (Augmented Dickey-Fuller) test and EG (Engle-Granger) test are first introduced to check the non-stationary order and calculate the co-integration coefficients of the frequency series. Subsequently, the theoretical derivation of frequency co-integration based technique is developed using a simply supported beam as an example, and the procedure of damage detection based on frequency co-integration technique under the influence of environmental temperature is introduced in detail. At last, the validity and robustness of the proposed method are illustrated and verified through a numerical simulation of a steel truss bridge and a real cable-stayed bridge under the influence of changing environmental temperature. Both the numerical simulation and the practical application demonstrate that the proposed frequency co-integration technique can effectively eliminate the influence of the changing environmental temperature and identify the structural damage accurately.

Comparison study between the Fourier and the Hartley transforms for the real-time simulation of the sea surface elevation

The paper presents the results of a comparison study between the Fourier and the Hartley transforms for the real-time simulation of the sea surface elevation in 3D. Fourier transforms are currently the most used and efficient method for obtaining realistic ocean scenes in interactive Virtual Environments. Although the Fast Fourier Transform has been the preferred choice for this type of simulations, the study reveals that the Fast Hartley Transform can be a valid alternative, and even have some advantages compared to the former. The study mainly focuses on the performance and memory aspects, which are decisive factors for real-time applications with ocean scenes, such as ship bridge simulators. The methodology to obtain the sea surface elevation in time domain from a sea state defined by a directional wave spectrum is also described.

Learning to navigate: the centrality of instructions and assessments for developing students\u2019 professional competencies in simulator-based training

Despite the promises of simulations to contribute to learning in safe-critical domains, research suggests that simulators are poorly implemented in maritime education and training systems. From the current state of research, it is far from evident how instruction in simulator-based should be designed and how skills trained in bridge simulators should be assessed and connected to professional practice. On this background, this article aims to investigate the role of instructions and assessments for developing students’ professional competencies in simulation-based learning environments. The research draws on ethnographic fieldwork and detailed analyses of video-recorded data to examine how maritime instructors make use of simulator technologies in a navigation course. Our results reveal an instructional practice in which the need to account for general principles of good seamanship and anti-collision regulations is at the core of basic navigation training. The meanings of good seamanship and the rules of the sea are hard to teach in abstraction because their application relies on an infinite number of contingencies that have to be accounted for in every specific case. Based on this premise, we stress the importance of instructional support throughout training (from briefing thorough scenario to debriefing) in order for the instructor to bridge theory and practice in ways that develop students’ competencies. Our results highlight, in detail, how simulator technologies enable displaying and assessing such competencies by supporting instructors to continuously monitor, assess, and provide feedback to the students during training sessions. Moreover, our results show how simulator-based training is related to the work conditions on board a seagoing vessel through the instructor’s systematic accomplishments. Finally, our results highlight the close relationship between technical and non-technical skills in navigation, and how these are intertwined in training for everyday maritime operations.

Damage identification of a large cable-stayed bridge with novel cointegrated Kalman filter method under changing environments

Damage identification is an indispensable part for successive applications of structural health monitoring. In practical applications, however, time-varying environmental and operational conditions, such as temperature and external loadings, often overwhelm the subtle structural changes caused by damage. It is therefore of great significance to remove those structural changes (damage features) caused by external influences from actual structural damage. In this paper, a new damage identification method based on Kalman filter and cointegration (KFC) is developed, and the environmental effects on damage indicator are removed by the cointegration process of the Kalman filtered coefficients. The cointegration relationship between structural frequencies is first established with augmented Dickey–Fuller test and Johansen procedure. The cointegration coefficients are then used to constitute the Kalman filter (KF) state vector, and the recursive KF process is intrigued to on-line estimate the change of structure states. To enhance the importance of incoming new observations in the KF, we introduce an adaptive fading factor into the conventional KF. Numerical simulation of a truss bridge is used to validate the effectiveness of the proposed KFC method for damage identification under varying temperature, even with 10% noise. Finally, the KFC method is applied to a cable-stayed bridge built in China (Tianjin Yonghe Bridge), and two structural damage scenarios are successfully identified. The advantages of the proposed KFC method are its ability to eliminate ambient temperature influences and identify structural damage on-line.

Structural damage diagnosis and fine scale finite element intelligence simulation of long span cable stayed bridges

According to the accumulation characteristics presented by the security threat factors existed in building structure, it is relatively difficult to carry out real-time danger monitoring. In addition, the noise and structure will form complex interference and make the real-time monitoring more difficult. Therefore, this paper proposes one bridge structure monitoring algorithm of restricted Boltzmann machine (SDRBM) based on sparse cross-entropy penalty factor. Firstly, the improvement of deep network learning process based on sparse cross-entropy penalty factor and restricted Boltzmann machine (RBM) has effectively resolved the homogenization problems existed in deep network learning process; secondly, the preset rough set is used to make pretreatment for input bridge health signals to achieve complete preservation of data information and balance of effective reduction as well as simplify treatment complexity; finally, the experiment shows that the proposed DRBM bridge structure monitoring algorithm of sparse cross-entropy penalty factor can achieve bridge safety monitoring under the condition of unknown noise and structure.

Profile of capillary bridges between two vertically stacked cylindrical fibers under gravitational effect

Although profiles of axisymmetric capillary bridges between two cylindrical fibers have been extensively studied, little research has been reported on capillary bridges under external forces such as the gravitational force. This is because external forces add significant complications to the Laplace–Young equation, making it difficult to predict drop profiles based on analytical approaches. In this paper, simulations of capillary bridges between two vertically stacked cylindrical fibers with gravitational effect taken into consideration are studied. The asymmetrical structure of capillary bridges that are hard to predict based on analytical approaches was studied via a numerical approach based on Surface Evolver (SE). The axial and the circumferential spreading of liquids on two identical fibers in the presence of gravitational effects are predicted to determine when the gravitational effects are significant or can be neglected. The effect of liquid volume, equilibrium contact angle, the distance between two fibers and fiber radii. The simulation results were verified by comparing them with experimental measurements. Based on SE simulations, curves representing the spreading of capillary bridges along the two cylindrical fibers were obtained. The gravitational effect was scaled based on the difference of the spreading on upper and lower fibers.

Multistage Indicial Functions and Postflutter Simulation of Long-Span Bridges

Multistage Indicial Functions and Postflutter Simulation of Long-Span Bridges

Validation of Capillarity Theory at the Nanometer Scale. II: Stability and Rupture of Water Capillary Bridges in Contact with Hydrophobic and Hydrophilic Surfaces

We perform molecular dynamics (MD) simulations of water capillary bridges formed between parallel walls. The underlying structure of the walls corresponds to hydroxilated (crystalline) β-cristobalite, modified to cover a wide range of hydrophobicity/hydrophilicity. The capillary bridges are stretched during the MD simulations, from wall–wall separation h = 5 nm up to h ≈ 7.5 nm, until they become unstable and break. During the stretching process, we calculate the profiles of capillary bridges as well as the force and pressure induced on the walls, among other properties. We find that, for all walls separations and surface hydrophobicity/hydrophilicity considered, the results from MD simulations are in excellent agreement with the predictions from capillarity theory (CT). In addition, we find that CT is able to predict very closely the limit of stability of the capillary bridges, i.e., the value of h at which the bridges break. We also confirm that CT predicts correctly the relationship between the surface...

An integrated explicit–implicit algorithm for vehicle–rail–bridge dynamic simulations

The dynamic interaction between the vehicle, rail, and bridges presents a huge computational challenge, especially for reliability analysis based on Monte Carlo simulations. In this study, an integrated algorithm is proposed for the vehicle–rail–bridge dynamic interaction problem. This algorithm divides the system into two subdomains, i.e. the vehicle–rail subdomain and the bridge subdomain. The vehicle–rail subdomain and the bridge subdomain are integrated by the Zhai algorithm and the Newmark-β algorithm, respectively. The integrated algorithm allows different time steps (or multitime steps) to be used for the two domains: a large time step for the bridge subdomain and a smaller one for the vehicle–rail subdomain. The stability region of the proposed algorithm was found through the two-degree-of-freedom model problem, when a single time step is used in both subdomains. The accuracy of the algorithm was numerically investigated through the two-degree-of-freedom model. The vehicle–rail–bridge vibration excited by rail irregularities and earthquakes was simulated using the multitime step algorithm. The effect of the time step ratio (ratio of the large time step to the small time step) on the accuracy of the vehicle–rail–bridge responses was investigated. It has been shown that the time step ratio of less than 50 produces vehicle–rail–bridge responses in an accurate manner for engineering purposes. The multitime step algorithm can solve the vehicle–rail–bridge problem 20 times faster than the single time step algorithms that are conventionally used in the vehicle–rail–bridge simulations. This multitime step algorithm provides an efficient alternative for solving the dynamic interaction between vehicle–rail and large-scale civil structures.

A proposed Evidential Reasoning (ER) Methodology for Quantitative Assessment of Non-Technical Skills (NTS) Amongst Merchant Navy Deck Officers in a Ship’s Bridge Simulator Environment

Ship’s bridge simulators are very popular in the worldwide training and assessment of merchant navy deck officers. The examiners of simulator courses presently do not have a method to quantitatively assess the performance of a group or an individual. Some examiners use checklists and others use their gut feeling to grade competence. In this paper a novel methodology is established that uses the Evidential Reasoning algorithm to quantitatively assess the Non‐Technical Skills (NTS) of merchant navy officers. To begin with, interviews were conducted with experienced deck officers to develop the taxonomy and behavioural markers that would be used in the assessment process. A random selection of students studying towards their Chief Officer’s Certificate of Competency were recruited to have their NTS to be observed in a ship’s bridge simulator. The participant’s behaviour was rated against five criteria and the subsequent data was entered into the Evidential Reasoning algorithm to produce a crisp number. The results that were generated demonstrate that this approach provides a reliable method to quantitatively assess the NTS performance of merchant navy officers in a simulated bridge environment.

Fatigue reliability evaluation of short-span concrete bridges under dynamic impacts of stochastic truck loading

This study presents an approach for the fatigue stress spectrum simulation of short-span bridges under the dynamic impacts of stochastic traffic loading. This approach is utilised to evaluate the fatigue reliability of existing bridges. Response functions defined by intervals are used to approximate the equivalent fatigue stress range of the bridge. Probability models of the fatigue stress ranges are evaluated with Gaussian mixture models. The effectiveness of the proposed method is validated via a case study of a simply supported bridge. The numerical results indicate that the impact effect of vehicle loads on short-span bridge leads to an obvious increase in both the stress range and the number of stress cycles. Both the degradation of the road surface roughness condition and the traffic growth lead to a significant decrease in the fatigue reliability.

Reducing the uncertainty of strain gauge amplifier calibration

<p class="Abstract">The article presents a method for calibration of strain gauge bridge amplifiers with improved uncertainty in low voltage ratio range. The procedure is based on combining traditional calibration of the amplifier at one point and linearity determination of the rest of the range. Traditional calibration is performed by a calibrated strain gauge bridge simulator at a reference value where measurement uncertainty is adequate, and the linearity is determined by a combinatorial calibration method with lower uncertainty, employing a special resistance circuit. Uncertainty in the lower part of the amplifier range can be significantly improved, resulting in a combined relative standard uncertainty below 2.5x10<sup>-5</sup> for the range from 0.04 mV/V to 2.5 mV/V.</p>

Conditional Reversible Work Coarse-Grained Models of Molecular Liquids with Coulomb Electrostatics - A Proof of Concept Study on Weakly Polar Organic Molecules.

Scale bridging simulations of soft matter rely on the availability of transferable coarse-grained models. In systematic coarse-graining approaches, core principles of statistical mechanics are used to relate the coarse-grained models to the underlying molecular interactions. The conditional reversible work (CRW) method provides effective, nonbonded pair potentials by means of computing coupling free energies between mapped chemical groups. This method has so far been used almost exclusively for systems composed of apolar organic molecules, but additional challenges arise when developing coarse-grained models for polar molecules in which (long-range) electrostatic interactions are important. Herein, we present a modified formulation of the CRW method where we divide the effective interaction potential into van der Waals and electrostatic components. The shape of the effective electrostatic interaction justifies modeling the electrostatics using a Coulomb potential with point charges on each site that are equal to the net charge of the underlying group of atoms. We perform CRW calculations using two polar molecules as test cases (an ether (1,2-dimethoxyethane) and an ester (ethyl propionate)). The results of subsequent liquid state simulations indicate that the coarse-grained models obtained by the new method are of similar quality with respect to representability and thermodynamic transferability as formerly developed models for apolar systems.

Experimental Simulation of Bridges Subjected by Moving Loads

The effect of bridge vibrationinduced bylive loads such as vehicles and pedestrians is an important factor of bridge fatigue damage. It takes much labor and material resource to perform vibration experiments on bridges subjected by real moving loads in field. In order to carry out laboratory experiments on bridges subjected by moving loads, a fixed load with harmonic vibration simulates a moving load on bridge in the beam theory. A simply supported bridge is considered in the present study. The dynamic responses of bridge under different loads are established by the analytic method. Amplitude and frequency of the simulated load are generated on the principle of equal displacements due to both a moving load and a fixed harmonic load impacting on a simply supported beam. Comparisons of numerical results of two types of load on the same beam indicate that the harmonic load can simulate a moving load effectively. It is possible that the field test on bridge can be carried out indoors.

Hydrodynamic Interaction Between Ships and Restricted Waterways

In open and unrestricted waters the water displaced by a forward sailing vessel can travel without major obstruction underneath and along the ship. In restricted and shallow sailing conditions, the displaced water is squeezed between the hull and the bottom and/or the bank. This results in higher flow velocities and as a consequence a pressure drop around the same hull. In the vicinity of a bank this pressure drop generates a combination of forces and moments on the vessel, known as bank effects. The major achievement of the presented research is the development of a realistic and robust formulation for these bank effects. This knowledge is acquired with an extensive literature study on one hand and with dedicated model tests carried out in different towing tanks on the other. The majority of the utilised model tests were carried out in the shallow water towing tank at Flanders Hydraulics Research in Antwerp, Belgium. The data set on bank effects consists of more than 8 000 unique model test setups (which is by far the most elaborate research ever carried out on this subject). These model tests provide the input for the analysis of bank effects and the creation of the mathematical model. Overall the magnitude of the bank induced forces increase with:  A higher forward speed of the ship  A higher propeller load  A lower under keel clearance  A more confined navigation area: steeper banks, smaller channel width  A smaller distance between ship and bank The mathematical model copes with a wide range of ship types and bank configurations and is suitable for implementation (and has been implemented) in full mission bridge simulators which can be used for training purposes as well as for research to support the admittance policy or exploitation of ports and waterways.