Applied sciences

Bulletin of the Polish Academy of Sciences: Technical Sciences

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Bulletin of the Polish Academy of Sciences: Technical Sciences | Early Access |

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Abstract

Evaluating soil strength by geophysical methods using P-waves was undertaken in this study to assess the effects of changed binder ratios on stabilisation and compression characteristics. The materials included dredged sediments collected in the seabed of Timrå region, north Sweden. The Portland cement (Basement CEM II / A-V, SS EN 197-1) and Ground Granulated Blast Furnace Slag (GGBFS) were used as stabilisers. The experiments were performed on behalf of the Svenska Cellulosa Aktiebolaget (SCA) Biorefinery Östrand AB pulp mill. Quantity of binder included 150, 120 and 100 kg. The properties of soil were evaluated after 28, 42, 43, 70, 71 and 85 days of curing using applied geophysical methods of measuring the travel time of primary wave propagation. The P-waves were determined to evaluate the strength of stabilised soils. The results demonstrated variation of P-waves velocity depending on stabilising agent and curing time in various ratios: Low water / High binder (LWHB), High water / Low binder (HWLB) and percentage of agents (CEM II / A-V/GGBFS) as 30%/70%, 50%/50% and 70%/30%. The compression characteristics of soils were assessed using Uniaxial Compressive Strength (UCS). The P-wave velocities were higher for samples stabilized with LWHB compared to those with HWLB. The primary wave propagation increased over curing time for all stabilized mixes along with the increased UCS, which proves a tight correlation with the increased strength of soil solidified by the agents. Increased water ratio gives a lower strength by maintained amount of binder and vice versa.

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Authors and Affiliations

Per Lindh
1 2
Polina Lemenkova
3
ORCID: ORCID

  1. Swedish Transport Administration, Gibraltargatan 7, Malmö, Sweden
  2. Lund University, Division of Building Materials, Box 118, SE- 221-00, Lund, Sweden
  3. Université Libre de Bruxelles (ULB), École polytechnique de Bruxelles (Brussels Faculty of Engineering), Laboratory of Image Synthesis and Analysis (LISA). Campus de Solbosch - CP 165/57, Avenue Franklin D. Roosevelt 50, B-1050 Brussels, Belgium
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Abstract

Low-Density Parity-Check (LDPC) codes are among the most effective modern error-correcting codes due to their excellent correction performance and highly parallel decoding scheme. Moreover, the nonbinary extension of such codes further increases performance in the short-block regime. In this paper, we review the key elements for the construction of implementation-oriented binary and nonbinary codes. These Quasi-Cyclic LDPC (QC-LDPC) codes additionally feature efficient encoder and decoder implementation frameworks. We then present a versatile algorithm for the construction of both binary and nonbinary QC-LDPC codes that have low encoding complexity and an optimized corresponding graph structure. Our algorithm uses a progressive edge growth algorithm, modified for QC-LDPC graph construction, and then performs an iterative global search for optimized cyclic shift values within the QC-LDPC circulants. Strong error correction performance is achieved by minimizing the number of short cycles, and cycles with low external connectivity, within the code graph. We validate this approach via error rate simulations of a transmission system model featuring an LDPC coder-decoder, digital modulation, and additive white Gaussian noise channels. The obtained numerical results validate the effectiveness of the proposed construction algorithm, with a number of constructed codes exhibiting either similar or superior performance to industry standard binary codes and selected nonbinary codes from the literature.
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Authors and Affiliations

Wojciech Sułek
1

  1. Silesian University of Technology, Gliwice, Poland
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Abstract

The article discusses an example of the use of graph search algorithms with trace of water analysis and aggregation of failures in the occurrence of a large number of failures in the Water Supply System (WSS). In the event of a catastrophic situation, based on the Water Distribution System (WDS) network model, information about detected failures, the condition and location of valves, the number of repair teams, criticality analysis, the coefficient of prioritization of individual network elements, and selected objective function, the algorithm proposes the order of repairing the failures should be analyzed. The approach proposed by the authors of the article assumes the selection of the following objective function: minimizing the time of lack of access to drinking water (with or without prioritization) and minimizing failure repair time (with or without failure aggregation). The algorithm was tested on three different water networks (small, medium, and large numbers of nodes) and three different scenarios (different numbers of failures and valves in the water network) for each selected water network. The results were compared to a valve designation approach for closure using an adjacency matrix and a Strategic Valve Management Model (SVMM).
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Authors and Affiliations

Ariel Antonowicz
1
Andrzej Urbaniak
1

  1. Institute of Computing Science, Poznan University of Technology, ul. Piotrowo 2, 60-965 Poznan, Poland
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Abstract

As nonlinear optimization techniques are computationally expensive, their usage in the real-time era is constrained. So this is the main challenge against researchers to develop a fast algorithm that is used in real time computations. This work proposes a fast nonlinear model predictive control approach based on particle swarm optimization for nonlinear optimization with constraints. The suggested algorithm's divide and conquer technique improves computing speed and disturbance rejection capability, demonstrating its suitability for real-time applications. The performance of this approach under constraints is validated using a highly nonlinear fast and dynamic real time inverted pendulum system. The solution presented trough work is computationally feasible for smaller sampling times and it gives promising results compared to the state of art PSO algorithm.
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Authors and Affiliations

Supriya P. Diwan
1
Shraddha S. Deshpande
2

  1. Government College of Engineering, Karad-415124, Maharashtra, India
  2. Walchand College of Engineering, Sangli-416415, Maharashtra, India
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Abstract

In this paper, the performance of the Bayesian Optimization (BO) technique applied to various problems of microwave engineering is studied. Bayesian optimization is a novel, non-deterministic, global optimization scheme that uses machine learning to solve complex optimization problems. However, each new optimization scheme needs to be evaluated to find its best application niche, as there is no universal technique that suits all problems. Here, BO was applied to different types of microwave and antenna engineering problems, including matching circuit design, multiband antenna and antenna array design, or microwave filter design. Since each of the presented problems has a different nature and characteristics such as different scales (i.e. number of design variables), we try to address the question about the generality of BO and identify the problem areas for which the technique is or is not recommended.
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Authors and Affiliations

Michal Baranowski
1
Grzegorz Fotyga
1
Adam Lamecki
1 2
Michal Mrozowski

  1. Gdańsk University of Technology, Gdańsk, Gabriela Narutowicza 11/12 80-233, Poland
  2. EM Invent Sp. z o.o., Gdańsk, Trzy Lipy 3 80-172, Poland
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Abstract

In this paper, a model of an electromagnetic system with two levitating magnets is presented. Modeling was performed using the results of experiments. The data obtained make it possible to fit the magnetic forces between two magnets using a 5th order polynomial. The time series show that dry friction constitutes an important part of damping forces. The differential equations of motion consider strong nonlinearities of magnetic and damping forces. These terms cause the nonlinear hardening effect. The energy recovered by magnetic induction is dissipated in the resistors. Numerical simulations show that resistance has an impact on magnet dynamics and energy recovery. From the resonance characteristics obtained, optimal resistance is determined when energy recovery is the highest.
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Authors and Affiliations

Andrzej Mitura
Krzysztof Kecik
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Abstract

The underframe passive inerter-based suspended device, based on the inerter-spring-damper vibration attenuation structure, could improve the dynamic performance of the train body, but its parameters are fixed and cannot meet the dynamic performance requirements under different operating conditions. Therefore, a semi-active inerter-based suspended device based on the linear quadratic regulator (LQR) control strategy is proposed to further enhance the dynamic performance. The rigid-flexible coupling vertical dynamic model of the train body and an underframe semi-active inerter-based suspended device are established. The structural parameters of the semi-active inerter-based suspended device are adjusted using LQR control strategy. Dynamic response of the system is obtained using the virtual excitation method. The dynamic characteristic of the system is evaluated using the Sperling index and compared with those of the passive and semi-active traditional suspended devices as well as the passive inerter-based suspended devices. The vertical vibration acceleration of the train body and Sperling index using the semi-active inerter-based suspended device is the smallest among the four suspended devices, which denotes the advantages of using the inerter and LQR control strategy. The semi-active inerter-based suspended device could decrease the vertical vibration acceleration of the train body and further suppress its elastic vibration in the lower frequency band, more effectively than the other three suspended devices. Overall, the semi-active inerter-based suspended device could significantly reduce elastic vibration of the train body and improve its dynamical performance.
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Authors and Affiliations

Yong Wang
Hao-Xuan Li
Hao-Dong Meng
Yang Wang
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Abstract

The performance of a novel airfoil-based tube with dimples is numerically studied in the present work. The effect of Reynolds number Re, dimples number N, relative depth H/D, and cross-distribution angle α on flow and heat transfer characteristics are discussed for Re in the range between 7,753 and 21,736. The velocity contour, temperature contour, and local streamlines are also presented to get an insight into the heat transfer enhancement mechanisms. The results show that both the velocity magnitude and flow direction change, and fluid dynamic vortexes are generated around the dimples, which intensify the flow mixing and interrupt the boundary layer, resulting in a better heat transfer performance accompanied by a certain pressure loss compared with the plain tube. The Nusselt number Nu of the airfoil-based tube increases with the increase of dimples number, relative depth, and Reynolds numbers, but the effect of cross-distribution angle can be ignored. Under geometric parameters considered, the airfoil-based tube with N = 6, H/D = 0.1, α = 0° and Re = 7,753 can obtain the largest average PEC value 1.23. Further, the empirical formulas for Nusselt number Nu and friction factor f are fitted in terms of dimple number N, relative depth H/D, and Reynolds number Re, respectively, with the errors within ± 5%. It is found that the airfoil-based tube with dimples has a good comprehensive performance.
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Authors and Affiliations

Houju Pei
Houju Liu
Kaijie Yang
Li Zhimao
Chao Liu

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