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Processing systems design considering resilience

Ákos Orosz Jean Pimentel Ferenc Friedler

Publication Name: Computer Aided Chemical Engineering

Publication Date: 2021-01-01

Volume: 50

Issue: Unknown

Page Range: 807-812

Description:

The resilience of a system is defined as the system's capability of recovering from failures. Traditionally, only predictable aspects are considered when designing processing systems. Evaluation of these aspects is performed via assessment of exact indicators and enumeration of all cause-effect options. However, such evaluation is not appropriate for determining the resilience of processing systems, since resilience is based on unexpected events in addition to the expected ones. Consequently, the cause part of the cause-effect relation is not known or not effective. In the current work, the general formula for determining resilience of a system is embedded into a P-graph based process synthesis algorithm. Thus, the resilience can be considered when selecting the most preferred process during its synthesis. The result is illustrated by synthesizing a process of adipic acid production by nitric acid oxidation of KA oil.

Open Access: Yes

DOI: 10.1016/B978-0-323-88506-5.50126-1

Sight distances at unsignalized intersections: A comparison of guidelines and requirements for human drivers and autonomous vehicles

Mariusz Kieć Csaba Koren Attila Borsos Zsófia Magyari

Publication Name: Archives of Transport

Publication Date: 2021-01-01

Volume: 59

Issue: 3

Page Range: 7-19

Description:

Many traffic accidents are caused by unforeseen and unexpected events in a site that was hidden from the driver's eyes. Road design parameters determining required visibility are based on relationships formulated decades ago. It is worth reviewing them from time to time in the light of technological developments. In this paper, sight distances for stopping and crossing situations are studied in relation to the assumed visual abilities of autonomous vehicles. Current sight distance requirements at unsignalized intersections are based among others on speeds on the major road and on accepted gaps by human drivers entering or crossing from the minor road. Since these requirements vary from country to country, regulations and sight terms of a few selected countries are compared in this study. From the comparison it is remarkable that although the two concepts, i.e. gap acceptance on the minor road and stopping on the major road have different backgrounds, but their outcome in terms of required sight distances are similar. Both distances are depending on speed on the major road: gap sight distances show a linear, while stopping sight distances a parabolic function. In general, European SSD values are quite similar to each other. However, the US and Australian guidelines based on gap acceptance criteria recommend higher sight distances. Human capabilities and limitations are considered in sight field requirements. Autonomous vehicles survey their environment with sensors which are different from the human vision in terms of identifying objects, estimating distances or speeds of other vehicles. This paper compares current sight field requirements based on conventional vehicles and those required for autonomous vehicles. Visibility requirements were defined by three vision indicators: distance, angle of view and resolution abilities of autonomous cars and human drivers. These indicators were calculated separately for autonomous vehicles and human drivers for various speeds on the main road and for intersections with 90° and 60° angles. It was shown that the required sight distances are 10 to 40 meters shorter for autonomous vehicles than for conventional ones.

Open Access: Yes

DOI: 10.5604/01.3001.0014.9553

Hungarian experiences of the transition from traditional work to telework1

No authors available

Publication Name: Transformations in Business and Economics

Publication Date: 2021-01-01

Volume: 20

Issue: 3

Page Range: 168-182

Description:

The global outbreak of the COVID-19 epidemic has radically transformed people’s daily lives since the spring of 2020. In addition to the direct health consequences of the virus, the epidemic has had a significant impact on the functioning of society, people’s lifestyles and has also had a fundamental impact on the world of work. The year 2020 marked a breakthrough in the spread of telework and “home office” work in Hungary, as this form of work was one of the necessary tools in the fight against the COVID-19 epidemic in order to reduce the number of personal contacts. Both employers and the masses of employees were able to experience the pros and cons of this. This period can be therefore considered as the main challenge of teleworking and working from home, which is undoubtedly caused by the COVID-19 epidemic. The research aims to answer the question of the impact of telework on the daily lives of Hungarian workers. In international comparison, the proportion of teleworkers in Hungary was low before the pandemic. As a result, a great many have experienced a drastic transition from traditional work to teleworking. The given questionnaire survey also confirmed that a significant proportion of employees had difficulties with teleworking at the beginning of the transition. These difficulties were mainly due to the fact that they were not technically prepared and that their daily routine, which they had become accustomed to in their traditional work, had been changed.

Open Access: No

DOI: DOI not available

Determination of center of gravity and moment of inertia using dynamic testing method

No authors available

Publication Name: "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021

Publication Date: 2021-01-01

Volume:

Issue:

Page Range: Unknown

Description:

The knowledge of a vehicle's center of gravity (COG) and moment of inertia (MOI) are important from vehicle dynamic and comfort points of view. These parameters can be determined from the CAD model of the vehicle, however, manufacturing inaccuracies and additional elements can modify the values, and experimental validation can be necessary. The determination of COG (and even MOI) can be carried out using classical physical methods, but a more convenient and sophisticated method is offered based on dynamic testing data. The method is known and accessible even in commercial testing software, but a clear recommendation for the optimal input data and the expected accuracy is still not available. The purpose of this study is to define the influencing factors of the measurement and quantify their effect. The introduced method is based on the evaluation of the frequency response functions in the mass-line region. Input data were obtained by using impulse hammer excitation and accelerometers for measuring the response of the structure. The measurements and the evaluations were performed in Siemens LMS Test.Lab software using Rigid Body Calculator module. The results of the dynamic measurement are compared to CAD data and to the COG value got from simple static measurement.

Open Access: No

DOI: DOI not available

Development of 1D and 3D acoustic simulation methods for transmission loss based on transfer matrix measurement results

No authors available

Publication Name: "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021

Publication Date: 2021-01-01

Volume:

Issue:

Page Range: Unknown

Description:

During the acoustical characterization of a component of a building, machine or vehicle, the normal incidence sound transmission loss is a major factor. Transmission loss simulation is also crucial in designing intake or exhaust elements, such as reflective mufflers. However, there is not enough information in the open literature about the applicable frequency ranges of experimental and 1- and 3D simulation methods. Therefore, the main purpose of this paper is to evaluate the frequency limits of computational and experimental transmission loss analyses of various reflective mufflers. For the validation two in-house impedance tube test benches were designed and multiple measurement setups were investigated. The combination of the four-pole matrix and the two-load methods was used during the experimental part of the study. In order to obtain appropriate transfer function results, distinct setups were evaluated, such as a low-frequency sound source with bigger tube diameter and a high-frequency sound source with smaller tube diameter. The low-frequency setup is suitable for the investigation of the system in the range of 30-500 Hz. The high-frequency setup is capable of measuring from 300 Hz to 2000 Hz, which is the upper frequency limit of the range of interest. Consequently, the in-house system is suitable for measuring the transmission loss in the 30-2000 Hz frequency range. 1D simulations were performed using Ricardo Wave software and 3D simulations were carried out in the STAR-CCM+ software. The upper cutoff frequency of 1D simulation method was determined to be 1500 Hz according to the correlation with the measurements. The frequency range of simulation could be extended up to 2000 Hz by employing 3D simulation for transmission loss calculations. This paper gives insights into the transmission loss measurements with the in-house system and the correlation analysis with different simulation methods.

Open Access: No

DOI: DOI not available

Development of tire-road noise measuring system

No authors available

Publication Name: "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021

Publication Date: 2021-01-01

Volume:

Issue:

Page Range: Unknown

Description:

In vehicles there are 3 main noise sources: powertrain noise (e.g. engine, gear engagement or exhaust noise), aerodynamic noise (or wind noise), and the noise from the tire-road contact. The first two are traditionally in the primary focus of vehicle manufacturers, however, due to both the already made powerful developments and the spreading of electric vehicles, the rolling noise is gaining more and more attention during the vehicle development process. There are two major influencing factors of this noise source: tire (geometrical and material) characteristics and road (surface) characteristics. The separation of their contribution is not straightforward, investigated rarely, and the requirements of homologation standards do not expect it neither. However, if one would like to meet the new vehicle pass-by noise regulations, it is more and more inevitable to have a sophisticated break-down of rolling noise. A straightforward solution is the usage of a one-wheel testbench developed directly for acoustical measurements. Such design process is presented in this paper, where the most important requirements are: enabling the users to compare tires from acoustical aspect under totally objective conditions, modelling the typical conditions of vehicles and ensuring data for rolling noise simulations. One further functionality of the testbench is to reproduce the real rolling noise by mounting realistic road surface sections onto the superficies.

Open Access: No

DOI: DOI not available

NVH characterization of a ladder-like welded structure using finite element analysis and experimental method

No authors available

Publication Name: "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021

Publication Date: 2021-01-01

Volume:

Issue:

Page Range: Unknown

Description:

In vehicle industry, considering a chassis, the evaluation of the experimental modal analysis is usually done up to 80 Hz, since the modal density is increasing with frequency. In addition, the deviation between the measurement and simulation is getting more significant at higher frequencies. The purpose of this study is to extend the usable test range and to improve the accuracy of the results both in case of measurement and FE (Finite Element) simulation. Present paper introduces the vibrational characterization of a ladder-like welded structure. This test case represents a simplified model of a vehicle's frame consisting of rod-like elements with high stiffness, connected to each other in welded junctions. Although such simulational and experimental modal analysis procedures are widely used in practice, results can significantly change according to the used method and the fine-tuning of parameters. For this reason, a further goal is to find the best measurement and simulation technique for the given structure. During the FE analysis different modelling solutions and element types were compared. In order to discover the effect of the manufacturing inaccuracies, the same measurements were performed on two distinct, but theoretically identical samples. The influence of the experimental setup (e.g. excitation and fixing method) and settings were investigated as well. Finally, FE simulation and experimental results are compared using Frequency Response Functions.

Open Access: No

DOI: DOI not available

Multiple hypothesis testing by unpaired samples for indexing changepoints in a road-induced vibration signal

No authors available

Publication Name: UPB Scientific Bulletin, Series D: Mechanical Engineering

Publication Date: 2021-01-01

Volume: 83

Issue: 3

Page Range: 17-28

Description:

Several methods have been developed for simulating non-stationary and non-Gaussian processes in packaging vibration testing, encompassing unique methods for the segmentation of road vehicle vibrations. However, only a limited number of those consider spectral characteristics. Thus, the current paper introduces a novel segmentation algorithm conducted in the time-frequency domain. The spectral characteristics obtained by short-time Fourier transform are compared by multiple hypothesis tests to find changepoints in a wheeled vehicle vibration sample. Different post hoc procedures are introduced against the inflating Type I. error.

Open Access: No

DOI: DOI not available

Systematic Design and Evaluation of Energy-Efficient Alternatives of Heterogeneous Azeotropic Distillation: Furfural Case Study

Jean Pimentel Ferenc Friedler

Publication Name: Chemical Engineering Transactions

Publication Date: 2021-01-01

Volume: 88

Issue: Unknown

Page Range: 619-624

Description:

Separation of azeotropic mixtures receives special attention for their impact on various significant industrial processes. Because of the non-ideal behaviour of these mixtures, it is impossible to separate them by conventional distillation. Instead of a single distillation unit, a system of multiple operations is to be employed. Heterogeneous azeotropic distillation (HAD) is an example of this kind of systems, where entrainers are applied to modify the behaviour of the mixture. The selection of the best separation system is a key objective during the synthesis of the process network. However, synthesis of HAD is especially difficult because of the complex interaction between its continuous and discrete features. Therefore, traditional separation network synthesis tools are incapable of solving this problem. In this work, the properties of the ternary vapor-liquid-liquid equilibrium diagram are exploited for systematically identifying plausible operating units that perform the separation of the azeotrope. Subsequently, energy consumption of the entire network is estimated through rigorous simulation. The P-graph framework is employed to represent the system’s structure. Additionally, its combinatorial algorithms generate a rigorous superstructure for the synthesis problem, and the set of n-best designs that minimize energy consumption. The method is illustrated by synthesizing the dehydration of furfural through HAD. The results demonstrate that it constitutes a valuable tool for the designer by being effective in the systematic identification and assessment of HAD alternatives.

Open Access: Yes

DOI: 10.3303/CET2188103