Compaction Problem Research Articles

GCKSign: Simple and efficient signatures from generalized compact knapsack problems.

In 2009, Lyubashevsky proposed a lattice-based signature scheme using the Schnorr-like identification and the Fiat-Shamir heuristic and proved its security under the collision resistance of a generalized compact knapsack function. However, their security analysis requires the witness indistinguishability property, leading to significant inefficiency and an increase of sizes of public key and signature. To overcome the efficiency issue associated with the WI property, we introduce a new lattice-based assumption, called the target-modified one-wayness problem of the GCK function and show its reduction to well-known lattice-based problems. Additionally, we present a simple and efficient GCK-based signature scheme, GCKSign, whose security is based on the Module GCK-TMO problem in the random oracle model. GCKSign is a natural extension of Lyubashevsky's scheme in a module setting, but achieves considerable efficiency gains due to eliminating the witness indistinguishability property. As a result, GCKSign achieves approximately 3.4 times shorter signature size and 2.4 times shorter public key size at the same security level.

On the Parameterized Complexity of Compact Set Packing

The Set Packing problem is, given a collection of sets S\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal {S}$$\\end{document} over a ground set U, to find a maximum collection of sets that are pairwise disjoint. The problem is among the most fundamental NP-hard optimization problems that have been studied extensively in various computational regimes. The focus of this work is on parameterized complexity, Parameterized Set Packing (PSP): Given parameter r∈N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$r \\in {\\mathbb N}$$\\end{document}, is there a collection S′⊆S:|S′|=r\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal {S}' \\subseteq \\mathcal {S}: |\\mathcal {S}'| = r$$\\end{document} such that the sets in S′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal {S}'$$\\end{document} are pairwise disjoint? Unfortunately, the problem is not fixed parameter tractable unless W[1]=FPT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extsf {W[1]} = \ extsf {FPT} $$\\end{document}, and, in fact, an “enumerative” running time of |S|Ω(r)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|\\mathcal {S}|^{\\Omega (r)}$$\\end{document} is required unless the exponential time hypothesis (ETH) fails. This paper is a quest for tractable instances of Set Packing from parameterized complexity perspectives. We say that the input (U,S)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$({U},\\mathcal {S})$$\\end{document} is “compact” if |U|=f(r)·poly(log|S|)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|{U}| = f(r)\\cdot \ extsf {poly} ( \\log |\\mathcal {S}|)$$\\end{document}, for some f(r)≥r\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f(r) \\ge r$$\\end{document}. In the Compact PSP problem, we are given a compact instance of PSP. In this direction, we present a “dichotomy” result of PSP: When |U|=f(r)·o(log|S|)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|{U}| = f(r)\\cdot o(\\log |\\mathcal {S}|)$$\\end{document}, PSP is in FPT, while for |U|=r·Θ(log(|S|))\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|{U}| = r\\cdot \\Theta (\\log (|\\mathcal {S}|))$$\\end{document}, the problem is W[1]-hard; moreover, assuming ETH, Compact PSP does not admit |S|o(r/logr)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|\\mathcal {S}|^{o(r/\\log r)}$$\\end{document} time algorithm even when |U|=r·Θ(log(|S|))\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|{U}| = r\\cdot \\Theta (\\log (|\\mathcal {S}|))$$\\end{document}. Although certain results in the literature imply hardness of compact versions of related problems such as Setr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$r$$\\end{document}-Covering and Exactr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$r$$\\end{document}-Covering, these constructions fail to extend to Compact PSP. A novel contribution of our work is the identification and construction of a gadget, which we call Compatible Intersecting Set System pair, that is crucial in obtaining the hardness result for Compact PSP. Finally, our framework can be extended to obtain improved running time lower bounds for Compactr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$r$$\\end{document}-VectorSum.

Solvability of nonlocal fractional vector functional boundary value problems with p‐Laplacian on a half‐line at resonance

In this paper, the solvability of a system of fully nonlinear Hilfer fractional differential equations on the half‐line is studied. Firstly, considering that the half‐line as the domain has the problem of insufficient compactness, we defined the space of weighting functions and normed the convergence at infinity. Secondly, by constructing appropriate operators in these Banach spaces and using the extension for the continuous theorem, some sufficient conditions for the solvability of the problem are obtained. Finally, an example is given to illustrate the main results.

Cryptographic primitives based on compact knapsack problem

The present paper builds upon prior research on an id scheme that utilizes a compact knapsack problem defined by a single equation. We introduce a three-move id scheme founded on a compact knapsack problem defined by an integer matrix. Through our analysis, we investigate the possible lattice-based attacks on this problem. Additionally, we present the corresponding digital signature gained through the Fiat–Shamir transform and demonstrate its security under ROM. These cryptographic primitives are potentially post quantum resistant.

The Least Limiting Water Range to Estimate Soil Water Content Using Random Forest Integrated with GIS and Geostatistical Approaches

In this study, as a result of the determination of the Least limiting water range (LLWR) contents of alluvial lands with different soils, which are distributed in the Bafra Plain where intensive agricultural activities are carried out, the compression and aeration problems in the area are revealed with distribution maps. In addition, the predictability of LLWR was evaluated with the random forest (RF) algorithm, which is one of the machine learning algorithms, and the usability of the prediction values distribution maps was revealed. The LLWR contents of the soils varied in the range of 0.049- 0.273 cm3 cm-3 for surface soils. While there were aeration problems in 6.72%, compaction problems in 20.16%, both aeration and compaction problems in 0.8% of the surface soils examined in the study area, 72.32% were determined under optimal conditions. For the 20-40 cm depth, an aeration problem in the 5.88%, a compaction problem in the 28.57%, and both an aeration and a compaction problem in the 2.52% of the points were detected. In the estimation of LLWR with the random forest algorithm, the RMSE value obtained for 0-20 cm depth was determined as 0.0218 cm3 cm-3, and for 20-40 cm it was determined as 0.0247 cm3 cm-3 . In the distribution maps of the observed and predicted values obtained, the lowest RMSE value was determined by Simple Kriging interpolation methods for 0-20 cm depth and Ordinary Kriging interpolation methods for 20-40 cm. While the distribution of obtained and predicted values in surface soils was similar, variations were found in the distribution of areas with low LLWR below the surface. As a result of the study, it has been revealed that LLWR can be obtained with a low error rate with the RF algorithm, and distribution maps can be created with lower error in surface soils.

Enhanced Atrous Extractor and Self-Dynamic Gate Network for Superpixel Segmentation

A superpixel is a group of pixels with similar low-level and mid-level properties, which can be seen as a basic unit in the pre-processing of remote sensing images. Therefore, superpixel segmentation can reduce the computation cost largely. However, all the deep-learning-based methods still suffer from the under-segmentation and low compactness problem of remote sensing images. To fix the problem, we propose EAGNet, an enhanced atrous extractor and self-dynamic gate network. The enhanced atrous extractor is used to extract the multi-scale superpixel feature with contextual information. The multi-scale superpixel feature with contextual information can solve the low compactness effectively. The self-dynamic gate network introduces the gating and dynamic mechanisms to inject detailed information, which solves the under-segmentation effectively. Massive experiments have shown that our EAGNet can achieve the state-of-the-art performance between k-means and deep-learning-based methods. Our methods achieved 97.61 in ASA and 18.85 in CO on the BSDS500. Furthermore, we also conduct the experiment on the remote sensing dataset to show the generalization of our EAGNet in remote sensing fields.

Cd2+-enhanced the structure, electrical and magnetic properties of low-temperature sintered NiCuZn ferrites

Ferrite materials are urgently demanded in high-frequency miniaturized power electronics for their high electromagnetic properties and high electrical resistivity. However, traditional NiZn ferrites are faced with low resistivity and high loss at low-temperature sintering, which severely restrict their applications. In this study, CdO was substituted into Ni0.22Cu0.2Zn0.58Fe2O4 ferrites at a presintered stage to refine the grain size and to achieve superior performance at low-temperature sintering. Interestingly, the electrical, magnetic and gyromagnetic properties of the NiCuZn ferrites exhibited a strong dependence on the concentration of Cd2+ ions. The Cd2+ ions entered into the lattice and substituted for Fe3+ at the octahedral site. SEM image results showed that CdO-substituted NiCuZn ferrites for the first sintering stage possess inhibition of abnormal grain growth, which can effectively solve the problem of shrinkage and grain compaction of ferrite materials in LTCC technology. Furthermore, to promote the grain growth at low sintering temperature, the optimized Bi2O3 additives were added at final sintering stage. The resistivity of the optimized Cd2+ ions is significantly enhanced from 2.41 × 108 Ω cm to 8.51 × 108 Ω cm. Finally, the NiCuZnCd (x = 0.15)-1.2 wt% Bi2O3 ferrites with the highest densification possess ρ = 8.51 × 108 Ω cm, ε′ = 18, tan δε = 6.0 × 10−3, μ′ = 81, fr = 117 MHz, tan δμ = 4.8 × 10−2 and ΔH = 281 Oe. This work provides a new doping method for the design of the high frequency LTCC device.

Rotational Tillage Practices to Deal with Soil Compaction in Carbon Farming

Conservation tillage practices, such as reduced tillage and no-tillage, have recently garnered significant attention as core elements of the regenerative agriculture and carbon farming concepts. By minimizing mechanical soil disturbance, these practices preserve soil carbon and facilitate CO2 fixation in the soil. Despite the widely acknowledged benefits, many farmers still approach no-tillage with skepticism. Their primary concerns are weed management and soil compaction. While weeds can be effectively controlled with the deployment of integrated weed management strategies, urgent soil compaction problems can be rapidly resolved only with mechanical interventions. That is why many no-till farmers resort to occasional heavy tillage, in a scheme characterized as rotational tillage, inadvertently sacrificing their regenerative assets in soil carbon. This is also a pivotal issue within carbon farming: the fate of soil carbon at the end of a compliant scheme focused on carbon fixation. The present study explores data of soil organic matter (SOM), soil penetration resistance (PR), and dry bulk density (DBD) from the initial, six-year period of a long-term tillage experiment in Greece. During that period, modifications to the experimental design allowed diverse combinations of five tillage methods (conventional tillage, 3 reduced tillage methods, and no-tillage). The findings indeed underscore the farmers’ concerns about soil compaction. High levels of PR and DBD were observed even at the topsoil layer of the no-tillage (NT). Conventional, moldboard plowing (MP) or reduced, chisel plowing (CP) applied after four years of uninterrupted no-tillage ameliorated most of the soil compaction; however, at the same time, this induced unfavorable consequences for SOM. In contrast, NT applied permanently for six years resulted in a substantial enhancement in SOM that reached 2.24%, for a sampling depth 0–0.30 m compared to 1.54% for permanent MP. When no-tillage was rotated with plowing in the fifth year, almost 50% of the sequestered carbon was lost and the SOM dropped to 1.87%. Nevertheless, the amount of SOM observed at the deeper 0.15–0.30 m layer was greater compared to permanent NT. This suggests that while plowing induced some loss of SOM, it also facilitated the uniform distribution into the soil profile, in contrast with the accumulation in the topsoil at prolonged NT. The permanent CP method and the NT/CP rotation provided comparative outcomes in terms of both soil compaction and soil carbon sequestration with the rotational NT/MP scheme, while all the other tillage combinations were inferior.

Some thoughts and experiments on Bergman’s compact amalgamation problem

AbstractWe study the question whether copies of $$S^{1}$$ S 1 in $$\textrm{SU}(3)$$ SU ( 3 ) can be amalgamated in a compact group. This is the simplest instance of a fundamental open problem in the theory of compact groups raised by George Bergman in 1987. Considerable computational experiments suggest that the answer is positive in this case. We obtain a positive answer for a relaxed problem using theoretical considerations.

Approximate contact solutions for non-axisymmetric homogeneous and power-law graded elastic bodies: A practical tool for design engineers and tribologists

In two recent papers, approximate solutions for compact non-axisymmetric contact problems of homogeneous and power-law graded elastic bodies have been suggested, which provide explicit analytical relations for the force–approach relation, the size and the shape of the contact area, as well as for the pressure distribution therein. These solutions were derived for profiles, which only slightly deviate from the axisymmetric shape. In the present paper, they undergo an extensive testing and validation by comparison of solutions with a great variety of profile shapes with numerical solutions obtained by the fast Fourier transform (FFT)-assisted boundary element method (BEM). Examples are given with quite significant deviations from axial symmetry and show surprisingly good agreement with numerical solutions.

Soil Density in Traditional Mouldboard Tillage

Abstract Until recently, mouldboard ploughing was used as the main tillage in almost the entire territory of Ukraine and Russia. However, mouldboard technologies contribute to the formation of a “plough pan”, which contributes to additional soil compaction. The intensity of agricultural production exacerbated the problem of soil compaction by machine and tractor units. The over-consolidation of soil results in stunted plant root growth, lack of oxygen, and water and nutrient restrictions. Soil compaction can be reduced by deep local chiselling. The aim of the study was to determine the density of the soil at different depths during continuous traditional cultivation (reverse ploughing). The density of the soil was evaluated by resistance to penetration into the soil in a vegetable-forage crop rotation on an experimental field with continuous traditional tillage. The measurement of penetration resistance was carried out using an automatic electronic hardness tester “DATAFIELD”. The boundaries of the experimental field were determined, a computer map of the experimental field was compiled with automatic “grid” of plot sizes, two-dimensional mapping was carried out, and the sequence and place of measurements were developed. As a result, the level of soil compaction at different penetration depths and resistance to root growth was determined. It has been established that with constant traditional reverse tillage, the soil at a depth of more than 10 cm is sufficiently compacted. At a depth of 15 cm, a strong compaction of the soil is observed, which indicates its physical and hydrological degradation.

Reduction in Soil Compaction by Utilization of Waste Tire Rubber

Hardpan is one of the major problems found in many parts of Thailand where monocropping and repeated plowing at the same depth are conducted. This work aimed to study the feasibility of using crumb rubber produced from waste tires to alleviate the soil compaction problem. Effects of particle size and loading of crumb rubber on the degree of soil compaction were investigated. The quality of water extracted from crumb rubber was also analyzed to determine the severity of environmental contamination. The scope of work was further extended into field tests. The results reveal that the addition of crumb rubber into sandy loam subsoil significantly reduced the bulk density of the compacted soil and permitted greater water permeation through the compacted soil layer. The effects were more pronounced with either increasing crumb rubber loading or reducing crumb rubber particle size. For the field test, the addition of small crumb rubber (S-crumb) at 30%wt. resulted in a significant reduction in penetration force in conjunction with a considerable increase in water permeability. The results clearly confirm the reduction in soil compaction by the addition of crumb rubber. From a quality analysis of the extracted water, most poisonous heavy metals were below the detection limits of the test equipment, except zinc.

Soil Properties and Maize Growth as Affected by Subsoiling and Traffic-Induced Compaction

Many of the current farm management methods that utilize production techniques tend to add to the soil compaction problem. The compaction from wheel traffic is a key source of soil deterioration in contemporary agriculture. Limited studies have been conducted over the heavy soil of Iraq’s southern regions to understand soil compaction under the current condition, and its effect on crop growth and yield. An experiment was conducted at two locations; with the goal of determining the effects of tractor traffic on soil parameters, plant development, and maize production. Compaction treatments included no traffic, t0; 8 tractor traffic, t8; 16 tractor traffic, t16; and 24 tractor traffic, t24. To reduce soil compaction’s negative impacts, two degrees of subsoiling have been investigated, nonsubsoiled (NonSub) and subsoiled (Sub) plots. The results showed that bulk density values through 10 to 40 cm soil profile after tractor traffic at both locations increased with increasing levels of compaction. Hydraulic conductivity of saturated soil cores showed a general trend of decreasing at both locations with increasing levels of compaction by tractor traffic. Maize plant height, 500-grain weight, and root mass throughout both growing locations were also lower with wheel traffic treatments compared to the control treatment. Maize yields with wheel traffic were significantly lower by 7.039, 19.120, 34.187% at the first location and by 7.291, 15.147, 26.862% at the second location for the t8, t16, and t24 than yields with the t0 treatments. On the other hand, subsoiling was found to mitigate the adverse effect of tractor traffic in the topsoil and in the subsoil that led to a favour effect on soil bulk density and saturated hydraulic conductivity. The subsoil treatment increased plant height at both growing locations due to the greater exploitation of root system at the subsoiled plots which increased 500 grain weight and eventually maize yield by 16.215 and 23.762% over nonsubsoiled treatment. Tractor traffic on agricultural soils must be planned in order to minimize its detrimental impacts, as demonstrated by the findings of this experiment. Tractor traffic below 16 passes, under the experiment condition, is convenient for effective maize cultivation. In addition, subsoiling can be a choice for alleviating compaction.

Data sensing and compaction condition modeling for asphalt pavements

Asphalt pavement compaction is a process of rearranging asphalt particles to reduce voids and increase density. Current empirical methods can sometimes cause compaction problems, particularly when new materials are implemented. This paper develops an innovative monitoring system to determine the compaction condition of asphalt pavement based on particle kinematics. Eleven asphalt mixtures were compacted in the laboratory, and two field compaction projects were carried out. A particle-size wireless sensor, SmartRock, was used to collect the particle kinematic behaviors during compaction. A compaction classification model and a density prediction model were established to predict the compaction condition. Similar particle rotation characteristics were identified under gyratory compaction and roller compaction, allowing the predictive models developed in the laboratory to estimate the field compaction. The predictions are in agreement with the measurement densities, which verifies the applicability of using the particle kinematics and intelligent model to predict the compaction of asphalt pavement.

Energy budgeting and productivity response of cotton-wheat cropping system to mechanical sub-soiling

ABSTRACT In North India, sub-soiling is required to alleviate the problem of soil compaction raised due to the use of heavy machinery. We have emphasized energy auditing to understand the practical feasibility of sub-soiling in cotton-wheat cropping system. Four sub-soiling treatments (cross and single side sub-soiling at 1.0 m, 1.5 m under both cases) in addition to conventional tillage were compared with conventional tillage alone at two sites. Sub-soiling improved crop yield by 13.5–33.7% in cotton and 13.0–22.0% in wheat as compared to control. Net monetary returns earned with sub-soiling were 98–408 and 159–287 US$/ha higher under cotton and wheat, respectively over control. Energy auditing suggested that sub-soiling treatments consumed 489–1504 MJ/ha extra energy in cotton season, however, net energy gain was higher in cotton (by 11,518–29,715 MJ/ha) and wheat (by 19,861–32,594 MJ/ha) over control. Energy use efficiency was higher under sub-soiling treatments in cotton (5.36–7.25) and wheat (9.55–10.46), whereas corresponding values under control were 4.64–6.18 and 8.18–8.36. Similarly, lesser specific energy was observed under sub-soiling treatments as compared to control. The present study concluded that sub-soiling increased cotton productivity and energetic returns as well as had the significant residual effect on wheat crop. These results clearly suggest that sub-soiling is a sustainable practice for cotton-wheat system in north-western India.

Seismic Performance of SFRC Shear Walls with Window Opening and the Substitution Effect for Steel Bars

Shear walls are important vertical and lateral bearing element in structures. While shear walls with openings are fragile due to stress concentration and the quasi-brittle behavior of concrete in tension. Therefore, additional strengthening rebars are required for the shear walls with openings. However, it aggravates the problem of dense reinforcement which increases the steel cage manufacturing and concrete compaction problem and still lacks countermeasures against concrete damage and cracking. To reduce the rebar demand and improve the damage tolerance of squat reinforced concrete (RC) shear walls with openings, an optimized steel-fiber-reinforced concrete (SFRC) was adopted to understand the seismic performance by cyclical loading test. The tested specimens included a plain RC shear wall without strengthening bar around the opening (for comparison), an SFRC shear wall, and an SFRC shear wall with a reduced distributed steel bar. This paper mainly studies the effect of using SFRC to improve the seismic performance of the open shear wall and to replace the reinforcement around the opening and the shear reinforcement. The hysteresis curves, skeleton curves, stiffness degradation, bearing capacity degradation and energy dissipation of the specimens were analyzed. The results show that the failure can be delayed and relieved, the deformation capacity and energy dissipation can considerably improve, and rebars can be partially replaced by using SFRC.

Research on the Rolling Process of SMA-13 Asphalt Surface Layer for Bridge Decks Based on Compaction and Skid Resistance Equilibrium Problems

In order to solve the equilibrium problem related to compaction degree, structural integrity of skid resistance, and skid resistance of asphalt wearing layer on a concrete bridge deck, the influence of rolling mode on compaction degree, structural integrity of skid resistance, and skid resistance performance was analyzed according to compaction curve characteristics, image processing technology, and laser method from the compaction mechanism and temperature control of rolling equipment. The results showed that the compaction degree and rolling times of an SMA-13 asphalt wearing course on the bridge deck could be characterized by a logarithmic model, and the model parameters had clear physical significance. Compared with the vibratory roller, the oscillation roller could achieve a greater and more stable compaction degree of the mixture and maintain a better density, compaction degree, and void ratio after 5 times of oscillation rolling. The pavement wear characteristics were extracted by a digital image method. The results showed that with the increase in rolling times, the rolling temperature decreased gradually, and the wear rate of surface texture increased significantly. The multiscale evaluation of pavement antiskid performance by a laser method showed that the surface structure gradually decreased and tended to be stable (1.2 mm) with the increase in rolling times of the vibratory roller, the microscopic texture density increased with the increase in rolling times, and the proportion of acute angle (<90°) in the peak angle of the surface texture profile decreased with the increase in rolling times. The SMA-13 asphalt wearing course on the bridge deck was rolled by a vibratory roller for 6 times, so as to achieve the balance of compaction degree, structural integrity, and skid resistance.

Mathematical programming formulations for the Collapsed k-Core Problem

In social network analysis, the size of the k-core, i.e., the maximal induced subgraph of the network with minimum degree at least k, is frequently adopted as a typical metric to evaluate the cohesiveness of a community. We address the Collapsed k-Core Problem, which seeks to find a subset of b users, namely the most critical users of the network, the removal of which results in the smallest possible k-core. For the first time, both the problem of finding the k-core of a network and the Collapsed k-Core Problem are formulated using mathematical programming. On the one hand, we model the Collapsed k-Core Problem as a natural deletion-round-indexed Integer Linear formulation. On the other hand, we provide two bilevel programs for the problem, which differ in the way in which the k-core identification problem is formulated at the lower level. The first bilevel formulation is reformulated as a single-level sparse model, exploiting a Benders-like decomposition approach. To derive the second bilevel model, we provide a linear formulation for finding the k-core and use it to state the lower-level problem. We then dualize the lower level and obtain a compact Mixed-Integer Nonlinear single-level problem reformulation. We additionally derive a combinatorial lower bound on the value of the optimal solution and describe some pre-processing procedures, and valid inequalities for the three formulations. The performance of the proposed formulations is compared on a set of benchmarking instances with the existing state-of-the-art solver for mixed-integer bilevel problems proposed in (Fischetti, Ljubić, Monaci, and Sinnl, 2017).

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.