Compaction Problem Research Articles

Investigation on the compaction process of steel bridge deck pavement based on DEM-FEM coupling model

ABSTRACT Compared with the compaction of general highway asphalt pavement, that of steel bridge deck pavement (SBDP) is more complicated and vulnerable due to special supporting conditions and severe construction environment. Besides, the existing simulation models are not suitable for the analysis of SBDP compaction. To clarify the compaction mechanism and characteristics of SBDP under unfavorable construction conditions, the particles were generated using a random particle generation algorithm and the asphalt mixture layer was simulated through the discrete element method (DEM); the steel bridge deck with weld seam was taken as an example of unfavorable external conditions and simulated through the finite element method (FEM). On this basis, the spatial movement and contact state of the particles during the compaction process were tracked and investigated using the DEM-FEM coupling model. Results show that the DEM-FEM coupling model is effective and feasible to simulate SBDP compaction process. The spatial movement and contact state of the particles are described. The findings could contribute to improving SBDP compaction quality. The coupling of DEM-FEM also provides the method reference to the research of other SBDP compaction problems, such as the influence of temperature field variation and bridge vibration.

A multi-UAV deployment method for border patrolling based on Stackelberg game

To strengthen border patrol measures, unmanned aerial vehicles (UAVs) are gradually used in many countries to detect illegal entries on borders. However, how to efficiently deploy limited UAVs to patrol on borders of large areas remains challenging. In this paper, we first model the problem of deploying UAVs for border patrol as a Stackelberg game. Two players are considered in this game: The border patrol agency is the leader, who optimizes the patrol path of UAVs to detect the illegal immigrant. The illegal immigrant is the follower, who selects a certain area of the border to pass through at a certain time after observing the leader's strategy. Second, a compact linear programming problem is proposed to tackle the exponential growth of the number of leader's strategies. Third, a method is proposed to reduce the size of the strategy space of the follower. Then, we provide some theoretic results to present the effect of parameters of the model on leader's utilities. Experimental results demonstrate the positive effect of limited starting and ending areas of UAV's patrolling conditions and multiple patrolling altitudes on the leader's utility, and show that the proposed solution outperforms two conventional patrol strategies and has strong robustness.

Compaction Prediction for Asphalt Mixtures Using Wireless Sensor and Machine Learning Algorithms

Compaction is a critical step in asphalt roadway construction to determine the pavement’s quality and service life. Current field compactions are mainly based on test strips and engineers’ experiences. Such empirical-based approaches sometimes cause compaction problems especially when new materials are implemented. Intelligent compaction (IC) technology was invented to improve compaction quality. The real-time collection and visualization of the pavement responses and temperature can greatly improve compaction uniformity. However, the material viscoelastic property and the complex pavement structure still hinder the establishment of the correlation between the Intelligent Compaction Measurement Value (ICMV) and the compactability of asphalt pavement. This paper aims to establish compaction prediction models based on machine learning (ML) algorithms and sensing technology. Given the strong correlation between the mixture’s compactability and the particle compaction characteristics, a particle-size wireless sensor, SmartRock, was used to collect the particle kinematic behaviors during compaction. 11 asphalt mixtures were compacted with an embedded SmartRock sensor. Three ML models and three dataset scenarios were applied to predict the compaction condition, and a higher than 98% prediction accuracy was achieved. The results revealed that combining the ML approach and sensing data is appropriate and practical for predicting the compaction condition of the asphalt mixture. Future studies shall further evaluate the algorithm based on field compaction data so that intelligent sensing technology can be implemented to improve compaction quality.

НОВІ ТЕНДЕНЦІЇ У ФОРМУВАННІ СУЧАСНОГО ОБРАЗУ БАГАТОПОВЕРХОВОГО ЖИТЛОВОГО БУДИНКУ

The article is devoted to a thematic study of new directions in the design of multistorey residential complexes. The factors affecting the conceptual and design decisions of architects are analyzed. The article provides examples of the most famous multistorey residential complexes built recently in different countries. The most famous building is the residential complex. «Interlacing» in Singapore. The project uses the principle of intersection of individual and public spaces in both horizontal and vertical directions. The author of the project abandoned the traditional vertical development scheme for Singapore, resulting in a unique example of a modern urban approach to housing design and organization of the natural environment. The second considered example of high-rise housing is the «Beirut Terraces» complex. The building is designed as a high-rise «shelf» at different levels of which there are apartments of different terraces that form the main artistic accent of the entire building. The building fits well into the surrounding dense urban development, while demonstrating the achievements of modern building technologies. The third example is the «Vancouver House», a multistorey residential complex with public premises on the first floors. structure, which fits into the so-called “parametrism” style, which has become especially relevant recently. The solution of the main building of the complex is interesting, especially its “anti-gravity” silhouette image. To create it, an internal cable-stayed system with vertically stretched metal cables was used. Multistorey residential buildings successfully solve the problem of compaction of residential development and increase the efficiency of the use of free territories, create economic prerequisites for organizing public spaces in the immediate vicinity of housing, which significantly increases the comfort and prestige of living in these complexes.

Pengaruh Tingkat Penjarangan Beri terhadap Kualitas Buah Anggur Kediri Kuning dan Prabu Bestari

One of the problems encountered in cultivating grapes is the low quality of the fruit, the size of the fruit is still relatively small, the taste is not sweet, and the bunches are relatively compact. The problem of compactness or density of fruit bunches causes the shape, size, and maturity of the fruit in the bunch to be less uniform and there are some broken and decayed fruits. Thus, it is necessary to support cultivation technology to support the success of grape cultivation in order to increase the yield and quality of the fruit, one of which is through berry thinning activities. The purpose of this study was to determine the effect of berry thinning on the quality of the Kediri Kuning and Prabu Bestari grape varieties. The method used was a split plot design with the basic design of a randomized block design (RBD). The treatments tested were varieties and levels of fruit thinning. The first factor (main plot) was the variety consisting of Kediri Kuning (V1) and the Prabu Bestari variety (V2), while the second factor (sub-plot) was thinning level (P) with a level consisting of P0 = 0% control (without thinning). , P1 = fruit thinning 10%-25%, P2 = fruit thinning >25%-40%, P3 = fruit thinning 40%-55%. The results showed that thinning of berries in P3 treatment (>40-55%) gave a significantly higher effect on the variables of berry weight, berry diameter, fruit bunch length, fruit bunch weight, total dissolved solids, and vitamin C content.

A Cluster-Based Partition Method of Remote Sensing Data for Efficient Distributed Image Processing

Data stream partitioning is a fundamental and important mechanism for distributed systems. However, use of an inappropriate partition scheme may generate a data skew problem, which can influence the execution efficiency of many application tasks. Processing of skewed partitions usually takes a longer time, need more computational resources to complete the task and can even become a performance bottleneck. To solve such data skew issues, this paper proposes a novel partition method to divide on demand the image tiles uniformly into partitions. The partitioning problem is then transformed into a uniform and compact clustering problem whereby the image tiles are regarded as image pixels without spectrum and texture information. First, the equal area conversion principle was used to select the seed points of the partitions and then the image tiles were aggregated in an image layout, thus achieving an initial partition scheme. Second, the image tiles of the initial partition were finely adjusted in the vertical and horizontal directions in separate steps to achieve a uniform distribution among the partitions. Two traditional partition methods were adopted to evaluate the efficiency of the proposed method in terms of the image segmentation testing, data shuffle testing, and image clipping testing. The results demonstrated that the proposed partition method solved the data skew problem observed in the hash partition method. In addition, this method is designed specifically for processing of image tiles and makes the related processing operations for large-scale images faster and more efficient.

Study on the properties of easy-compaction and high-durability modified asphalt and mixture

ABSTRACT In order to solve the problems of difficult compaction and poor durability of ultrathin overlays, the performance of easy-compaction and high-durability (ECHD) modified asphalt and mixtures were studied. Taking matrix asphalt and SBS modified asphalt as the control group, the high- and low-temperature rheological properties of the asphalt were analysed by MSCR and BBR. The asphalt samples were observed and analysed by fluorescence microscope and infrared spectrometer, and the road performance, compaction performance and surface functional durability of the asphalt mixture were tested. The results show that the ECHD asphalt has the best high- and low-temperature properties. The modifier particles are uniformly dispersed in the asphalt, which can form a dense network structure and a stable system. The ECHD asphalt mixture has good low temperature and water stability, and the high-temperature stability is slightly lower than that of the SBS-modified asphalt mixture, but meets the requirements of the specification. It has the smallest compaction energy index CEI, and the largest compaction rate K. Before and after wearing 30,000 times, the asphalt mixture has the best wear resistance and surface texture, and the surface functional durability is the best. This paper provides a reference for material selection of ultrathin overlays.

Effective nonlocal behavior of peridynamic random structure composites subjected to body forces with compact support and related prospective problems

We consider a static problem for statistically homogeneous matrix linear bond-based peridynamic composite materials (CMs) subjected to body force with compact support. Estimation of the effective displacements is performed by the exploitation of the most popular tools and concepts used in conventional local elasticity of composite materials (CMs) with their adaptation to peridynamics. The method is based on estimation of a perturbator introduced by one inclusion inside the infinite peristatic matrix subjected to the body force. The statistical averages of both the displacements and stresses are estimated by summation of these perturbators for all possible locations of inclusions. It leads to obtaining of a new general integral equation (GIE) where a renormalizing procedure is not required for the involved absolutely convergent integrals. It allows us to estimate not only the effective nonlocal constitutive equation but also to evaluate the statistical field averages (inhomogeneous and nonlocal) inside the phases at the fine scale that is critically important for advanced modeling (e.g. for any nonlinear phenomena potentially considered in the future). In particular, in the generalized effective field method (EFM) proposed, the effective field is evaluated from self-consistent estimations using closing of a corresponding integral equation in the framework of the quasi-crystalline approximation. In so doing, the classical effective field hypothesis is relaxed, and the hypothesis of the ellipsoidal symmetry of the random structure of CMs is not used. The method proposed is a promising ingredient at the construction of provably robust data-driven surrogate equations describing both the effective behavior and effective displacement concentration operator inside inclusions. Some opportunities for generalizations of the method proposed are considered. Numerical results for the estimation of effective deformations are obtained for one-dimensional (1D) statistically homogeneous peridynamic composite bar with the prescribed self-equilibrated body forces.

Analysis of Soil Penetration Resistance in Coffee Plantation Agroecosystems in Bangelan, Malang, East Java

Agriculture land shows soil compaction problems due to long-term agricultural cultivation activities. Soil compaction indicator can be seen from the value of soil penetration resistance at different soil depths (0 - 60 cm). This research aimed to determine soil penetration resistance at different coffee plantation ages with different soil depths and to analyze the relationship between soil penetration resistance with soil physical characteristics and coffee productivity. The survey activities include observation of minipits, measuring soil penetration resistance at soil depths of 0-20 cm, 20-40 cm, and 40-60 cm using a hand penetrometer, and soil sampling. The results showed that the soil penetration resistance at each LU and soil depth suggested variation were categorized into moderate and high soil penetration resistance classes (1.34 MPa - 3.35 MPa). Soil characteristics, such as soil aggregate stability, water content, bulk density, porosity, silt content, and clay content, significantly correlate with soil penetration resistance. However, soil penetration resistance has a negative correlation with coffee productivity. The value of soil penetration resistance (at a depth of 0-60 cm) has a significant negative correlation with the average productivity of coffee plantations (r=-0.5936**). Therefore, increased soil penetration resistance decreased root growth, decreasing plant productivity.

Preparation of the non-cohesive soil sample and calibration of the pneumatical launcher in the dynamic soil test SHPB

The paper analyzes the problem of initial compaction of a non-cohesive soil sample on the example of dry silty sand samples. Two different compaction methodologies were used: I) dynamic compaction - using split Hopkinson pressure bar and II) vibration compaction - using a vibrating shaker. A better result of the compaction process was obtained for dynamic compaction with an initial pressure value of 0.5 bar (small difference in the result - both methods obtained comparable results). The paper also includes a numerical analysis of the calibration of the pneumatic launcher in the Matlab environment on the basis of the system of difference equations. The calibration process was carried out in the initial pressure range from 0.5 to 3.0 bar for three different variants of the bar-projectile length: 100 mm, 200 mm and 250 mm and compared with the experimental analysis - the results were consistent.

On compact classes of Beltrami solutions and Dirichlet problem

This article is devoted to the study of the problem of compactness of solutions of the differential Beltrami equation with degeneration. We study the case when the complex characteristic of the equations satisfies the constraints of integral type. In this case, we have proved a theorem on the compactness of the class of homeomorphic solutions of the Beltrami equation, which satisfy the hydrodynamic normalization condition at infinity. Another important result is the compactness theorem for the class of open discrete solutions of the Dirichlet problem for the Beltrami equations in the Jordan domain, the imaginary part of which vanishes at some predetermined inner point.

ANALYSIS OF INFILTRATION RATES OF SOILS ON THE INNER SLOPES OF THE LAKE SFÂNTA ANA CRATER

The present study consists of the comparative analysis of infiltration rates of soils under different land-cover conditions (dirt trails, grass plots and different types of forest stands) on the inner slopes of the Sfânta Ana crater, the catchment area of Lake Sfânta Ana in Romania. According to historical data, the depth and the surface of Lake Sfânta Ana have been undergoing significant changes during the last century, it lost in depth and the surface area shrunk approximatively 1,5 hectares. The losses are considered to be the consequences of the sedimentation as a result of the inflow processes from the catchment area, reduction of water level and eutrophication. The assessment and comparative analysis of steady infiltration rates of soils under different land-use categories in the catchment area were carried out to identify the possible sources of generation of surface flows responsible for sediment transport towards the lake using In Situ determinations with Double Ring Infiltrometers (DRI). Statistically significant differences were found between samples collected from grass plots, forests and the dirt trails, and within different forest stand structures. Results show that dirt trails and grass plots can be held responsible for the generation of surface flows. The main cause of low infiltration rates is soil compaction. Different forest stands are characterized by steady infiltration rates with high values and therefore provide effective protection. High forest coverage must be maintained in the crater, the problem of soil compaction on grass plots and dirt trails must be addressed.

Assessment of Soil Physical Quality and Water Flow Regulation under Straw Removal Management in Sugarcane Production Fields

Removing sugarcane straw to increase bioenergy production can generate significant income to the industry. However, straw contributes to the regulation of soil functions and consequently supports the provision of ecosystem services, such as water flow regulation. Thus, straw removal may hinder the provision of these services, especially in mechanized sugarcane production systems, which have soil compaction problems due to machinery traffic. In this study, we assess a six-year experiment in Brazil with four rates of straw removal: 0 Mg ha−1 (TR), 5 Mg ha−1 (HR), 10 Mg ha−1 (LR), and 15 Mg ha−1 (NR) remaining straw. Using attributes, such as soil bulk density, porosity, water infiltration, runoff, saturated hydraulic conductivity and available water-holding capacity, as indicators of key soil functions, we calculated a soil-related ecosystem service (ES) index for water flow regulation provision. The ES index revealed that water flow regulation was low regardless of the straw management (0.56, 0.63, 0.64 and 0.60 for TR, HR, LR and NR, respectively). It can be a consequence of soil compaction caused by machinery traffic throughout the successive cycle, whose straw was unable to mitigate this issue. Thus, by the end of the sugarcane cycle (sixth ratoon), straw removal had little effect on soil physical and hydraulic indicators, and consequently had little impact on the provision of the soil-related ES associated with water flow regulation. Nevertheless, straw management should be planned to consider other functions and soil-related ES benefited by straw retention.

A new multi-commodity flow model to optimize the robustness of the Gate Allocation Problem

The Gate Allocation Problem (GAP) is one of the numerous operational problems that all busy airports have to handle and to optimize every day. In this article, we focus on two important objectives for the GAP: the robustness and the taxiing times. We first analyze a basic model which optimizes the robustness of the solution to the GAP and propose a more realistic and compact Multi-commodity Flow Problem model (MFP) to optimize both the robustness and the taxiing times. Based on tests with real data at Paris-Charles-de-Gaulle airport, this new efficient MFP model outperforms the basic one by orders of magnitude.

On the compactness problem for a family of generalized Seiberg–Witten equations in dimension 3

We prove an abstract compactness theorem for a family of generalized Seiberg-Witten equations in dimension three. This result recovers Taubes' compactness theorem for stable flat $\mathbf{P}\mathrm{SL}_2(\mathbf{C})$-connections as well as the compactness theorem for Seiberg-Witten equations with multiple spinors. Furthermore, this result implies a compactness theorem for the ADHM$_{1,2}$ Seiberg-Witten equation, which partially verifies a conjecture by Doan and Walpuski.

Utilizing Matrix Completion for Simulation and Optimization of Water Distribution Networks

Simulation of water distribution networks (WDNs) constitutes a key element for the planning and management of water supply systems. The literature presents different formulations of heads-flows equations that differ in terms of dimensionality, computational cost, and solution accuracy. Whereas this problem has been the subject of active research in the past, in the last decades a state of stagnation was reached and no new formulations were introduced. In this study, we propose a novel formulation that utilizes a matrix completion technique to construct a reduced-size nonlinear system of equations that guarantees both mass and energy conservation. The advantages of the proposed method are demonstrated in simulation and optimization settings. In the former, the method demonstrates improved scalability and accuracy as compared with other widely known formulations. In the latter, the new formulation leads to compact optimization problems that result in better performance in terms of the objective function, run time, and rate of successful optimization runs.

Oil Friction Loss Evaluation of Oil-Immersed Cooling In-Wheel Motor Based on Improved Analytical Method and VOF Model

Oil-immersed cooling provides an effective cooling scheme for high-power hub motors with compact structure and serious heating problems. However, with this cooling method, some oil friction loss will be generated, making the output torque and efficiency of the motor lower, which limits its application in the motor. It is essential to get an exact calculation of the oil friction loss so that it can be reduced in the future research. Firstly, a new method was proposed to improve the accuracy of oil friction loss calculated by an existing analytical method (Kori’s method), while the influence laws of oil-soaked depth and rotation speed on it were explored. Secondly, a three-dimensional transient Computational Fluid Dynamic (CFD) model based on Volume of Fluid (VOF) was established, considering the actual complex structure and the disorderly mixing of oil and air inside the motor. Finally, the oil friction loss calculated with an improved analytical method and a VOF model was verified by a testing. It was indicated that the VOF model was more precise but more time-consuming. The proposed method has the second highest accuracy but takes less time.

Soil compaction response to wheel traffic in the Rolling Pampas region of Argentina


 The present work shows the effects of the different agricultural wheels traffic on the soil physical properties on a Typic Argiudoll soil worked under no-tillage cropping system. Soil compaction produced by traffic was quantified through these parameters: a) cone index, b) rut depth and c) soil water content at the traffic moment. Grain chaser, sprayer, harvester combine and tractor equipped with commonly used wheels in the study area were tested. The main results obtained showed that the tyres with the highest inflation pressure and tyre ground pressures produced the highest values of cone index and rut depth. Typic Argiudoll soil worked under continuous no-tillage cropping system is not able to constrain topsoil and subsoil compaction when it is wheeled by tyre with ground pressures greater than 77.6 kPa.
 Highlights
 
 Soil compaction causes a reduction in root growth and yield in many crops.
 Soil under a no-tillage system does not limit topsoil and subsoil compaction when wheeled by tyres with ground pressures greater than 77.6 kPa
 When the machinery load increases on soils with high bearing capacity (soils under a long-term no-tillage system), the subsoil compaction problems increase.

The Nirenberg problem on high dimensional half spheres: the effect of pinching conditions

In this paper we study the Nirenberg problem on standard half spheres (mathbb {S}^n_+,g), , n ge 5, which consists of finding conformal metrics of prescribed scalar curvature and zero boundary mean curvature on the boundary. This problem amounts to solve the following boundary value problem involving the critical Sobolev exponent: (P)-Δgu+n(n-2)4u=Kun+2n-2,u>0inS+n,∂u∂ν=0on∂S+n.\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$\\begin{aligned} (\\mathcal {P}) \\quad {\\left\\{ \\begin{array}{ll} -\\Delta _{g} u \\, + \\, \\frac{n(n-2)}{4} u \\, = K \\, u^{\\frac{n+2}{n-2}},\\, u > 0 &{}\\quad \\text{ in } \\mathbb {S}^n_+, \\\\ \\frac{\\partial u}{\\partial \\nu }\\, =\\, 0 &{}\\quad \\text{ on } \\partial \\mathbb {S}^n_+. \\end{array}\\right. } \\end{aligned}$$\\end{document}where K in C^3(mathbb {S}^n_+) is a positive function. This problem has a variational structure but the related Euler–Lagrange functional J_K lacks compactness. Indeed it admits critical points at infinity, which are limits of non compact orbits of the (negative) gradient flow. Through the construction of an appropriate pseudogradient in the neighborhood at infinity, we characterize these critical points at infinity, associate to them an index, perform a Morse type reduction of the functional J_K in their neighborhood and compute their contribution to the difference of topology between the level sets of J_K, hence extending the full Morse theoretical approach to this non compact variational problem. Such an approach is used to prove, under various pinching conditions, some existence results for (mathcal {P}) on half spheres of dimension n ge 5.

Convex Polygonal Hull for a Pair of Irregular Objects

Introduction. Optimization placement problems are NP-hard. In most cases related to cutting and packing problems, heuristic approaches are used. The development of analytical methods for mathematical modeling of the problems is of paramount important for expanding the class of placement problems that can be solved optimally using state of the art NLP-solvers. The problem of placing two irregular two-dimensional objects in a convex polygonal region of the minimum size, which is a convex polygonal hull of the minimum area or perimeter, is considered. Continuous rotations and translations of non-overlapping objects are allowed. To solve the problem of optimal compaction of a pair of objects, two algorithms are proposed. The first is a sequentially search for local extrema on all feasible subdomains using a solution tree. The second algorithm searches for a locally optimal extremum on a single subdomain using a "good" feasible starting point. Purpose of the paper. Show how to construct a minimal convex polygonal hull for two continuously moving irregular objects bounded by circular arcs and line segments. Results. A mathematical model is constructed in the form of a nonlinear programming problem using the phi-function technique. Two algorithms are proposed for solving the problem of placing a pair of objects in order to minimize the area and perimeter of the enclosing polygonal area. The results of computational experiments are presented. Conclusions. The construction of a minimal convex polygonal hull for a pair of two-dimensional objects having an arbitrary spatial shape and allowing continuous rotations and translations makes it possible to speed up the process of finding feasible solutions for the problem of placing a large number of objects with complex geometry. Keywords: convex polygonal hull, irregular objects, phi-function technique, nonlinear optimization.