Partial Connection Research Articles

Experimental and Numerical Study on the Mechanical Behavior of Prestressed Continuous Composite I-Girder Bridges with Partial Connection

A partial connection–prestressing (PCP) method is proposed in this paper to decrease the prestress that was transferred to steel girders in the negative moment region of steel–concrete composite bridges. The partial connection is achieved by the application of rubber-sleeved studs (RSS) in the prestressed concrete slab in the negative moment region. Since there is no experimental research on the PCP method in continuous composite girders, to the best of the authors’ knowledge, two continuous composite girders were tested under a four-point static load to evaluate their mechanical performance. The test results showed that without decreasing the ultimate strength and overall stiffness of the steel–concrete composite girders, the PCP method enhanced the cracking load (Pcr) 3.1 times. In addition, 12.5% of the prestressing force was transferred into the steel girder at the internal support section with the PCP method, and the girder without the PCP reached 25.9%. Then, to elucidate the partial interaction effect and prestressing effect on continuous girders’ mechanical behavior, numerical models were developed and calibrated with the test results. From the numerical analysis, compared with normal composite girders, the application of RSS or prestressing could improve Pcr by 11.8% and 157.0%, respectively, and the value increases to 234.3% when RSS and prestressing are applied at the same time. The results indicate that the application of RSS in the negative moment region could effectively increase the prestressing efficiency in the concrete slab and enhance the bridge's durability.

DEFORMATION CAPACITY AND DUCTILITY OF SHEAR CONNECTORS

AbstractDeformation capacity and slip range (eventually called “ductility”) of shear connectors are key parameters for the design of shear connectors in composite beams, especially in partial shear connection. Existing design rules require a deformation capacity of at least 6 mm for the use of shear connectors with plastic design methods. This rule is combined with the assumption of rigid‐ideal plastic behaviour of the shear connectors. Still, the real characteristics of most of today's usual shear connectors differ considerably from these assumptions, even more for shear connectors used in combination with metal decking. The paper describes the results of a literature research conducted in order to obtain reliable values for the deformation capacity and the slip range of headed stud shear connectors. Based on these results, advanced design methods can be used to realise composite beams with more realistic lower limits for the degree of partial shear connection and thus better economic performance.

Motif-GCNs With Local and Non-Local Temporal Blocks for Skeleton-Based Action Recognition.

Recent works have achieved remarkable performance for action recognition with human skeletal data by utilizing graph convolutional models. Existing models mainly focus on developing graph convolutional operations to encode structural properties of a skeletal graph, whose topology is manually predefined and fixed over all action samples. Some recent works further take sample-dependent relationships among joints into consideration. However, the complex relationships between arbitrary pairwise joints are difficult to learn and the temporal features between frames are not fully exploited by simply using traditional convolutions with small local kernels. In this paper, we propose a motif-based graph convolution method, which makes use of sample-dependent latent relations among non-physically connected joints to impose a high-order locality and assigns different semantic roles to physical neighbors of a joint to encode hierarchical structures. Furthermore, we propose a sparsity-promoting loss function to learn a sparse motif adjacency matrix for latent dependencies in non-physical connections. For extracting effective temporal information, we propose an efficient local temporal block. It adopts partial dense connections to reuse temporal features in local time windows, and enrich a variety of information flow by gradient combination. In addition, we introduce a non-local temporal block to capture global dependencies among frames. Our model can capture local and non-local relationships both spatially and temporally, by integrating the local and non-local temporal blocks into the sparse motif-based graph convolutional networks (SMotif-GCNs). Comprehensive experiments on four large-scale datasets show that our model outperforms the state-of-the-art methods. Our code is publicly available at https://github.com/wenyh1616/SAMotif-GCN.

SAGGING BENDING RESISTANCE OF COMPOSITE SLABS IN PARTIAL SHEAR CONNECTION

AbstractThis document presents a proposal for improving the partial shear connection method used for the calculation of sagging bending resistance of composite slabs. The improvement is aimed in particular at the equilibrium model of the section of the slab at the ultimate limit state, taking into account the interaction between the tensile force in the sheeting and its resistance moment.

YOLO-DoA: A New Data-Driven Method of DoA Estimation Based on YOLO Neural Network Framework

Direction-of-arrival (DoA) estimation is one of the most promising technologies in array signal processing. Existing data-driven methods for DoA estimation are usually implemented by classification networks, which suffer from insufficient utilization about features of sources and require spectral peak-search stage. In this letter, we reframe DoA estimation as a target detection problem and propose a novel DoA estimation approach on the basis of the you only look once v3 (YOLOv3) framework, namely YOLO-DoA. DoAs of sources with confidence scores are directly predicted from the spectrum proxy with YOLO-DoA and an end-to-end estimation is realized. By combining squeeze-and-excitation operation, cross stage partial connections, and an improved loss function for bounding box regression, the performance of YOLO-DoA is enhanced. Simulation results demonstrate that the proposed approach outperforms several state-of-the-art methods in terms of network size, computational cost, prediction time, and accuracy of DoA estimation.

Structural Behaviour of Aluminium–Timber Composite Beams with Partial Shear Connections

In this paper, the short-term behaviour of innovative aluminium–timber composite beams was investigated. Laminated veneer lumber panels were attached to aluminium beams with screws. Recently conducted theoretical, experimental, and numerical investigations have focused on aluminium–timber composite beams with almost full shear connections. However, no experiments on aluminium–timber composite beams with partial shear connections have yet been conducted. For this reason, composite action in composite beams with different screw spacing was studied in this paper. Four-point bending tests were performed on aluminium–timber composite beams with different screw spacing to study their structural behaviour (ultimate load, mode of failure, load versus deflection response, load versus slip response, and short-term stiffness). The method used for steel–concrete composite beams with partial shear connection was adopted to estimate the load bearing capacity of the investigated aluminium–timber composite beams. The resistance to sagging bending of the aluminium–timber composite beams with partial shear connections from the theoretical analyses differed by 6–16% from the resistance in the laboratory tests. In addition, four 2D numerical models of the composite beams were developed. One model reflected the behaviour of the composite beam with full shear connection. The remaining models represented the composite beams with partial shear connections and were verified against the laboratory test results. Laminated veneer lumber was modelled as an orthotropic material and its failure was captured using the Hashin damage model. The resistance to sagging bending of the aluminium–timber composite beams with partial shear connections from the numerical analyses were only 3–6% lower than the one from the experiments.

A novel deep learning framework for detecting seafarer’s unsafe behavior

The accurate detection of seafarers’ unsafe behaviors is of great significance to improve the ship navigation safety. This study proposes an improved deep learning framework with a self-made dataset to detect the unsafe behavior of seafarers on duty. In order to increase the detection speed, the improved Cross Stage Partial connections (CSP) module is proposed to replace the original CSP module in the neck network of traditional algorithm. The efficient channel attention (ECA) module is also introduced to the backbone network of conventional algorithm as the attention mechanism network. In addition, the learning and representation capacities of the improved deep learning framework are promoted by redesigning the sizes of anchor boxes. The experiment results show that the proposed framework outperforms traditional object detection algorithms (e.g., YOLOv5s, R-CNN) in detecting seafarers’ unsafe behaviors because of the much higher detection speed and detection accuracy.

ANÁLISE TEÓRICA PELO MÉTODO DA RESISTÊNCIA DIRETA DE SEÇÕES DUPLAS DE PERFIS DE AÇO FORMADOS A FRIO SOB COMPRESSÃO

The need for lighter, lower-cost construction has intensified, so the presence of cold-formed profiles has become common in civil construction, offering greater efficiency in the ability to withstand the current demands. The present article aimed at the theoretical study on the stability of double U and U lipped sections, composed of cold formed steel profiles, submitted to compression. Under the justification of analyzing the effectiveness of this type of structural element, with the help of the CUFSM Software that uses the Finite Strip Method, and verify the resistance by the Direct Strength Method (DSM). The objectives of this study were: to investigate the modeling in the CUFSM software for a double section with profiles connected to each other; and apply the DSM to the theoretical analysis of double sections with Brazilian commercial profiles. It was found that the variation in the number of connections influences the analysis and can reproduce the partial connection behavior. The application of folds proved to be efficient, with little influence on local instability and considerable influence on distortion instability. The DSM showed a loss of resistance for the models that presented a local failure mode, being, therefore, the most important factor regarding the resistance.

Influence of partial shear connection on the behaviour of U-shaped steel concrete beams with L-shaped shear connectors

This paper presents a study on the influence of partial shear connection on the behaviour of the U-shaped steel concrete beams (USCB) with L-shaped shear connectors. An experimental campaign of three full-scale experimental tests on the USCB with a degree of shear connection ranging from 0.4 to 1 has been conducted under sagging bending moment. The test results showed high ductility of the USCB with both full and partial shear connections. The failure mode of the USCB was governed by the plastic buckling of the upper flanges of the U-shaped steel profile at the location of the shear connectors. The plastic moment resistance of the USCB with partial shear connection predicted by the full plastic analysis approach and by the simplified approach in Eurocode 4 agreed well with the experimental results. Furthermore, the flexural stiffness of the USCB with partial connections predicted by American and Australian standards fit well with the experimental results. A numerical model based on the two-layer beam element formulation taking into account the interlayer slips with continuous connection in a co-rotational framework was also adapted to determine the behaviour of the USCB. This model was validated against experimental tests as well as against the analytical approaches. It was finally used to carry out a parametrical study in order to investigate the effect of selected parameters such as the degree of shear connection, the concrete strength and the steel strength of U-shaped profile.

The gender dimension of vulnerability in disaster caused by the coronavirus (COVID-19)

The subject of the research is an examination of the way in which the disease COVID-19 affects the gender aspects of the vulnerability of citizens, with special reference to their physical, socio-economic and psychological vulnerability. For the purposes of this research, the perception of risk and the preparedness of men and women for the SARS-CoV-2 virus pandemic were examined. The results of this research were obtained by applying a quantitative survey of the citizens of the Republic of Serbia about their experiences and attitudes regarding their vulnerability due to the COVID-19 pandemic, where special attention is paid to the gender dimension. A survey of 273 adult citizens was conducted and the results have shown that there is no significant connection between the gender category and the physical vulnerability of people caused by the COVID-19 pandemic. The obtained data indicate that approximately the same percentage of women and men had severe symptoms of the disease. Nevertheless, the results showed that there is a partial connection between the gender category and socio-economic vulnerability, as well as a clear connection between the gender category and the psychological vulnerability of people caused by the pandemic. In both cases, the results indicate that women are more vulnerable socio-economically and psychologically than men. As this topic is not sufficiently represented in foreign, and especially not in domestic literature, the results of this research can serve as guidelines for future investigations of the gender dimension of people in the conditions of disasters, such as the COVID-19 pandemic.

A Three-Way Decision Approach for Water Resources System Resilience Evaluation and Its Application

Resilience is a significant uncertainty thought of water resources system security. Compared with risk analysis, resilience pays more attention to the ability of water resources system itself to deal with adverse events. However, a standard system of water resources system resilience’s concept and evaluation have not yet formed. In view of this, this study had attempted to decompose the process of resisting interference of water resources system and analyzed the characteristics and influencing factors of three sub processes of resistance, recovery and adaptation. Furtherly, a new resilience evaluation index system of water resources system was explored and a three-way dicision approach for water resources system resilience analysis based on variable fuzzy sets and partial connection number was developed. Specifically, a multi-grade quantitative evaluation of water resources resilience was carried out based on variable fuzzy sets method, and then the quantitative evaluation results were transformed into qualitative decision-making results using a new three-way decision model based on partial connection number of set pair analysis. Finally, a case study of China’s Yangtze River Economic Belt (YEB) in 2008–2017 was performed and the results show that the resilience of water resources system in the YEB does not show an obvious improvement trend, or even almost stagnant. Of the 110 samples, 83.6% were at the medium level. Only 6.4% are barely at the excellent level, but they are basically in Shanghai.

Innovative inner sleeve composite bolted connections for modular steel constructions: Experimental and numerical studies

The application scenarios of modular steel constructions (MSCs) are becoming more and more extensive due to their exceptional advantages: minimum on-site work, and higher construction speed and quality. Inter-module connections are the critical components, which can significantly affect the integrity and seismic behavior of MSCs. This study proposed an innovative inner sleeve composite bolted connection which combines blind bolts, high-strength bolts and inner sleeve to improve the constructability and seismic behavior. Experimental tests on four full-scale cruciform connections composed of hollow structural steel (HSS) columns and H-section steel beams with different configurations were carried out under cyclic load. The failure modes, moment-rotation relations, initial rotational stiffness, ductility and energy dissipation were analyzed. GB 50011–2010 was used to evaluate the seismic performance and verify the applicability for the seismic design of the proposed connection, in which the lower limit of elastic inter-story drift ratio [θe] is 0.004 rad (or 1/250) and that of elasto-plastic inter-story drift ratio [θp] is 0.02 rad (or 1/50). The yield inter-story drift ratio, [θy] = 4.00–6.75[θe], and the ultimate inter-story drift ratio, [θu] = 1.00–2.00[θp] for the test specimens under cycle load, demonstrating the satisfactory deformation capacity and ductility. Furthermore, EC3 Part 1–8 was adopted to evaluate the stiffness characteristic of the proposed connection, indicating that the proposed connection can be classified as a “semi-rigid” and partial strength connection. Finally, refined numerical models calibrated against the experimental results were established and parametric evaluation was conducted based on the numerical models. The results demonstrate that the effect of the thickness of the inner sleeve and column in the panel zone and the diameter of the blind bolt and vertical high-strength bolt is insignificant. The presented research will provide useful references for further application and popularization of MSCs.

Application of Partial Connection Number and Subtraction Set Pair Potential in Evaluation of Development Trend of Water Environment Bearing State

Aiming at the uncertainty between the evaluation samples and the evaluation standards in the evaluation of water environment carrying capacity, a five-element connection coefficient evaluation model for water environment carrying capacity based on the set pair analysis theory is constructed, and the partial connection coefficient method and the subtractive set pair potential method are used. The development trend of the water environment carrying state was analyzed, and the method was used in the dynamic evaluation of the water environment carrying capacity in HJ City. The results show that the water environment carrying capacity of HJ city in 2015-2021 is between grades IV and III, and the water environment carrying capacity is poor, but the overall potential is developing from partial antipodal to homogeneous, showing a development trend for the better. According to the comprehensive index evaluation results, targeted suggestions for improving the water environment carrying capacity are put forward. From the analysis, it can be seen that the above dynamic evaluation and analysis results are reasonable and reliable, and the method is intuitive and simple, which can provide a reference basis for the improvement of regional water environment quality.

The Digital Calculus of Racial Capitalism

The Digital Calculus of Racial Capitalism

Influence mechanism of Steel-concrete interlayer partial shear connections on mechanical properties of composite girders

A reduction in composite action using a partial shear connection (PSC) in the hogging moment region of a steel–concrete bridge can mitigate the concrete tensile cracking risk while maintaining the structural ultimate bearing capacity. To date, specific mechanical effects, important for the establishment of evaluation theory, have not been studied. To this end, four girders and six push-out specimens were tested for the effect investigation. Numerical analysis with material damage plasticity models and an analytical study were conducted for parametric and mechanistic investigations. The push-out test results showed that a wrapping rubber sleeve reduced the shear stiffness of the stud by 91.9%, whereas its strength varied slightly. The girder test results showed that arranging rubber sleeved stud (RSS) connectors in the composite girders reduced the girder load-carrying capacity and bending stiffness by 17% and 12%, respectively. Moreover, the concrete tensile cracking performance was improved. The analysis results showed that, for reducing the concrete tensile stress, the RSS connector in the girder had a more favourable effect on prestress distribution than increasing the ordinary stud spacing. In addition, an evident stress concentration appeared when the stud distance was increased. According to the analytical analysis of the girder under negative bending, the concrete tensile stress is exponentially related to the interlayer stud stiffness, and the exponential is expected to be 5/3. The research revealed the detailed mechanical behaviour of the girder with a PSC and simultaneously compared the effects of the two PSC methods. This research will help establish design and evaluation methods for PSC action.

A methodological proposal from situated knowledge epistemology: Narrative Productions

ABSTRACT The Narrative Productions’ Methodology emerges from Haraway’s epistemological and political concept of “situated knowledges”. According to this perspective, all knowledge emerges from semiotic and material conditions that give rise to a specific gaze, which diverges from both a gaze “from nowhere” – realism – and a gaze “from everywhere” – relativism. Unlike realist and relativist perspectives, the Narrative Productions’ Methodology reintroduces the notion of an “author” localized in a web of relations and speech genres. Furthermore, in the Narrative Productions’ Methodology, the alternative to the critique of the representation of others through the research act – typical of traditional research – consists in the possibility of partial connections with those close to the phenomenon under study. Thus, this methodology suggests that the research team connects with these positions over several sessions. This procedure will produce a hybrid text that expresses a certain way of understanding the phenomenon and guarantees the participants’ agency over the product. This article will introduce the fundamental principles of this methodology using a study on the events that happened in Barcelona in June 2001 on the occasion of the World Bank summit.

Risk Assessment Model Based on Set Pair Analysis Applied to Airport Bird Strikes

In order to comprehensively evaluate the risk of bird strike at airports and effectively prevent the occurrence of bird strike events, this paper constructs the risk assessment index system of airport bird strike from five perspectives of “personnel-bird-equipment-environment-management”. For the purpose of maximizing variances, the Analytic Hierarchy Process (AHP) and the entropy weight method are combined and used to obtain the comprehensive weights. The five-element connection number of Set Pair Analysis (SPA) is introduced to establish the identical-discrepancy-contrary airport bird strike risk assessment model, and the risk trend is analyzed according to the partial connection number for each order. The experiment results show that the combined weighting method can minimize the weight deviation and demonstrate good accuracy in determining the weights of indicators at all levels. The established airport bird strike risk assessment model can reasonably predict the risk trend, which is significant for airport personnel to carry out bird strike prevention works.

Parallel strips coupled split ring resonators for a desktop wireless charging system overcoming irregular route restrictions

In order to achieve efficient long-distance wireless charging and avoid the influence of irregularity of the transmission path, a desktop wireless power transmission (DWPT) implementation method based on parallel-strips-coupled split ring resonators (PSSRR) was proposed in this paper. In the DWPT system, the power was transmitted from the transmitting coil (Tx) to the receiving coil (Rx) through the magnetic resonance coupling and guiding of the PSSRR. The PSSRR consisted of two split ring resonators (SRRs), the dielectric disk above each SRR and two parallel conductor strips for the SRRs’ connection. The SRR and the dielectric disk can realize effective mutual conversion between magnetic field and propagating mode through near field magnetic resonance coupling. The parallel conductor strips were applied to achieve efficient power transmission in the first-ordered mode. The transmission characteristics of the DWPT systems with coplanar or non-coplanar bent paths were analyzed. The simulated and experimental results verified the feasibility and robustness of the DWPT system. Under the plane bent path, the transmission efficiency of the proposed DWPT system can reach 76 % at a transmission distance of 1900 mm. The proposed method provided a solution for long distance WPT through required irregular path or multi-path. The system still had the problem that partial intermediate connection was needed and surrounding metal or high permittivity materials affected the transmission characteristics. Further research can be carried out from these two aspects.

BNAS-v2: Memory-Efficient and Performance-Collapse-Prevented Broad Neural Architecture Search

In this article, we propose BNAS-v2 to further improve the efficiency of broad neural architecture search (BNAS), which employs a broad convolutional neural network (BCNN) as the search space. In BNAS, the single-path sampling-updating strategy of an overparameterized BCNN leads to terrible unfair training issue, which restricts the efficiency improvement. To mitigate the unfair training issue, we employ a continuous relaxation strategy to optimize all paths of the overparameterized BCNN simultaneously. However, continuous relaxation leads to a performance collapse issue that leads to the unsatisfactory performance of the learned BCNN. For that, we propose the confident learning rate (CLR) and introduce the combination of partial channel connections and edge normalization. Experimental results show that 1) BNAS-v2 delivers state-of-the-art search efficiency on both CIFAR-10 (0.05 GPU days, which is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> faster than BNAS) and ImageNet (0.19 GPU days) with better or competitive performance; 2) the above two solutions are effectively alleviating the performance collapse issue; and 3) BNAS-v2 achieves powerful generalization ability on multiple transfer tasks, e.g., MNIST, FashionMNIST, NORB, and SVHN. The code is available at <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><uri>https://github.com/zixiangding/BNASv2</uri></monospace> .

Foreign Body Detection in Rail Transit Based on a Multi-Mode Feature-Enhanced Convolutional Neural Network

Detection of railway traffic objects is an important task during train driving and is implemented to ensure safe driving. Although object detection has been investigated for years, many challenges exist in precisely detecting railway objects under complex railway scenes. These challenges mainly include adverse weather states, various railway backgrounds, diverse railway objects, and low-quality images. To address these issues, we introduce a novel deep learning method, called a multi-mode feature enhanced convolutional neural network (MMFE-Net), for accurate railway object detection. The network mainly consists of three modules. 1) An improved cross-stage partial connection darknet53 (CSPDarknet53), called adaptive dilated cspdarknet53, is used as our backbone to reduce image information loss. 2) A spatial feature extraction module is used to improve the feature extraction ability of the model for blurred objects and objects in a complicated background. 3) We introduce an attention fusion enhance module to strengthen the context information between adjacent feature maps to accurately detect multiscale and small objects. The proposed method achieves 0.9439 mAP and 79 FPS with an input size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$640\times 640$ </tex-math></inline-formula> pixels on the railway traffic dataset, and its performance is better than that of YOLOv4. Moreover, it is feasible to apply MMFE-Net into practical applications of railway object detection.