Additive Manufacturing(AM) has revolutionized the production industry by offering design freedom with shorter lead times and reduced material wastage. However, the damage tolerance of AM parts is a significant concern due to their microstructural and geometric complexities, which affect their mechanical performance. This article aims to provide a comprehensive overview of the manufacturing parameters affecting the damage tolerance of components produced by AM specifically selective laser melting(SLM). Detailed discussions are presented on the effects of manufacturing attributes on the microstructure, defects, and mechanical characteristics of AM parts. Depending on these aspects, basic concepts are studied and critically explained specifically for AM materials. The basic criterion for damage-tolerant component design, the criterion for fatigue and fracture properties, and the effect of the defects on fatigue life are critically presented. In addition, the effect of different types of gradation on the crack growth behavior of AM samples processed by SLM is also investigated in depth. There is currently a lack of a specific review study in the literature that establishes a connection between process attributes and metallographic properties, and their impact on the damage behavior of additively manufactured parts. This gap in research highlights the need for a comprehensive review to bridge this knowledge deficit and provide valuable insights for understanding the relationships between manufacturing processes, material characteristics, and the structural integrity of additively manufactured components. This review concludes by addressing the challenges and opportunities in designing and qualifying AM parts for damage tolerance.

Aiming at the optimal scheduling problem of virtual power plant ( VPP ) with multiple uncertainties on the source-load side, this paper proposes a two-stage stochastic robust optimal scheduling method considering the uncertainty of the source-load side. This method combines the characteristics of robust optimization and stochastic optimization to model the source-load uncertainty differentiation. The Wasserstein generative adversarial network with gradient penalty ( WGAN-GP ) is used to generate electric and thermal load scenarios, and then K-medoids clustering is used to obtain several typical scenarios. The min-max-min two-stage stochastic robust optimization model is constructed, and the column constraint generation ( C & CG ) algorithm and dual theory are used to solve the problem, and the scheduling scheme with the lowest operating cost in the worst scenario is obtained.

The operation of offshore vessels is directly related to the use of flexible pipelines. The article describes in detail the analysis of power, geometric, kinematic and technological parameters that affect the main operational characteristics of these pipes during their operation under water, in rough sea conditions and under wind loads. The article describes the degree of dependence between loads on the pipeline and velocity of the oncoming flow, the geometry of the pipe and the distance to the rigid surface of the ship’s hull or the seabed. It was determined how the flow velocity during parametric oscillations of the pipeline in unrestricted flow and near the surface of the seabed affects the change in its drag and lift coefficients. An estimate of operational limits of flexible pipeline instability was obtained. On the base of changes in distributed load, specific values for safe lengths of pipelines were formulated. It has been stated that the probability of failure-free operation of a flexible pipeline at a level of 0.99 is directly determined by the frequency of its oscillation. Its numerical values should always be at a level that does not exceed 3.7% of the frequency of pipe dynamic oscillations.

Ball mills are commonly used in chemical and mineral processing industries for particle size reduction. In mineral processing, cylindrical drums with wear resistant materials are used various operation scales. Polygon shaped mills have found application by artisanal and small-scale miners (ASM) due technological and economic reasons. Evaluating this kind of mills is key in improving or replacing them based on technological data. A modest improvement in grinding efficiency and mill durability can lead to significant economic and environmental benefits. In this study, the performance of polygonal shaped mills was evaluated and compared with cylindrical profiles considering power draw, collision energy dissipation, relative wear and operational stability. Discrete element method (DEM) was used to carry out simulations to describe mechanical behavior of grinding media and the interaction with the mill walls. Polygonal shaped mills without lifters promoted more interparticle interaction with limited centrifuging of particle even at higher speeds compared to cylindrical mills without lifters. Installation of lifters in polygon increased inter-particle collisions and reduce power draw and relative wear. Cylindrical mill with lifters had high interparticle collisions similar to polygonal profile with much lower cumulative relative wear and high operational stability.

Under the background of ”dual carbon”, we must develop clean energy, build integrated energy systems (IES), and optimize their operation to achieve carbon neutrality. This study presents a strategy for the IES, whose goal is to reduce the carbon content of the power system, which aims to constrain the carbon emission of IES further, improve energy conversion efficiency, and reduce the carbon content of IES. First of all, we focus on the current situation and the improvement of the economic efficiency of the carbon trading market and introduce a tiered and hierarchical electricity carbon trading mechanism to promote IES to control carbon emissions more effectively. Then, we refine the two-stage operation process of power to gas (P2G) and propose a P2G process. This novel approach can significantly enhance the efficiency of hydrogen energy utilization and save operational expenses. In addition, this paper proposes a flexible supply and demand dual response mechanism. On the supply side, energy efficiency is improved through cogeneration with adjustable heat and power ratio. On the demand side, the efficiency of the cogeneration system in terms of energy should be improved through a flexible supply and demand side dual response mechanism. With this mechanism, the environmental protection and economic viability of IES can be further enhanced.

The interaction between the structure and soil is the key factor for infrastructure stabilization in permafrost engineering. In this study, the shear mechanical behavior of the interface between concrete and permafrost under different normal stiffness, temperature and water content is investigated by using the interface direct shear test under temperature-controlled conditions. The results show that with the increase of temperature and water content, the initial shear stiffness of the interface shear stress-shear displacement curve gradually increases, and the interface shear strength gradually increases. Different normal stiffnesses have a small effect on the morphology of the interfacial shear stress-shear displacement curve, but have a significant effect on the peak shear strength. The peak shear strength increases significantly with the increase of normal stiffness, and this trend is more obvious with the decrease of temperature. The corresponding interfacial cohesion and friction angle also increase with the increase of normal stiffness.

A simple wideband magneto-electric (ME) dipole antenna is presented in this letter. In particular, two pairs of L-shaped slots with different sizes are successively etched out of the pair of horizontal patches of electric dipole, which can enlarge the bandwidth of ME dipole antenna without increasing the antenna size. Two new resonant frequency points are generated respectively at the lower and upper frequency region. To improve the impedance matching characteristics, two vertical rectangular patches are loaded in the middle of the horizontal portion of the Г-shaped feed structure. A prototype is fabricated and measured, and an overlapped bandwidth of 101.3% (from 1.36 GHz to 4.15 GHz) in terms of VSWR≤2 is achieved, which can simultaneously cover the n50 (1.432GHz-1.517GHz), n51(1.427GHz-1.432GHz), and n78 (3.300GHz to 3.800GHz) bands of sub-6G. It should be highlighted that other excellent properties of ME dipole antenna, such as stable radiation pattern, high gain, and low cross-polarization level (CRPL), are maintained, which makes the proposed ME dipole antenna a good candidate for sub-6G applications.

The goal was to evaluate the hysteresis performance of segmented buckling resistant braces with low yield point steel LYP160, the monotonic tensile and cyclic loading tests of LYP160 were conducted and the corresponding laws have been obtained. According to the load-displacement curves of the specimen, the low yield point steel was characterized by good ductility and energy absorption ability. With the consideration of Chaboche model on the materials, the cyclic loading was simulated by ABAQUS and the cyclic hardening parameters of low yield point steel were obtained. On this basis, the hysteretic properties of buckling resistant braces under cyclic loads were simulated and analyzed. After the analysis and comparison of buckling resistant braces specimens with isotropic core plate and segmented variable section core plate, it can be found that: When the buckling resistant braces with isotropic core plate was loaded to L/100, the lateral deformation of BRB would reach 17mm and the seriously squeezed would observe on lateral constraint members. The buckling resistant braces would fail due to the accumulation of deformation on lateral constraint members at both ends of BRB. When the segmented buckling resistant braces was applied, the core plate with variable section would yield first in the middle part, other parts could still continue to consume energy due to the action of the limit plate. It would avoid the phenomenon that other parts could not continue to consume energy after the core plate failed at one point first. Under the action of cyclic loads, the stiffness of the segmented buckling resistant brace was constant and the better ability to consume energy was reflected.

The essential factor in developing multi-robot systems is the generation of an optimal path for task completion by multiple robots. This paper studies the recent publications and provides a detailed review of the path planning approaches to avoid collisions in uncertain environments. In this article, path planning approaches for multiple robots are categorized primarily into classical, heuristic, and artificial intelligence-based methods. Among the heuristic approaches, bio-inspired approaches are mostly employed to optimize the classical approaches to enhance their adaptability. The articles are analyzed based on static and dynamic scenarios, real-time experiments, and simulations involving hybrid solutions. The increasing focus on using hybrid approaches in dynamic environments is found mostly in the papers employing heuristic and AI-based approaches. In real-time applications, AI-based approaches are highly implemented in comparison to heuristic and classical approaches. The findings from this review can help researchers select the appropriate approach to overcome the limitations in designing efficient multi-robot systems.

This study utilizes plant-derived fibers including Mikania, wool, kapok, sugarcane and pineapple as strengthening additions to fabricated and tested reinforced polyester mixtures. This study aimed to examine the mechanical qualities and potential applications of these natural materials in boosting the effectiveness of polyester composites. The composites were formed by including natural fibers into a polyester base using a hands-on preparation method. The finished samples received a complete assessment, covering tensile and impact testing as well as SEM analysis. The findings showed that incorporating natural materials like Mikania vines, wool, Kapok fuzz, sugarcane fibers, and pineapple leaves had a notably positive effect on the mechanical features of the plastic composites. The tensile strength of the material combined pineapple was particularly high, achieving a maximum stress of 42.4822 N/mm 2 and a maximum stretch of 4.27950%. Similarly, that same composite exhibited the greatest maximum stretch of 3.75753% and the highest maximum stress of 77.4922 N/mm 2 during the bending experiment. The substances exhibiting the strongest impact endurance, as determined by the impact assessment, were the ones including Kapok, Mikania, wool, pineapple, and sugarcane. The kapok provided an impact toughness of 1.2 Newton meters, which was somewhat elevated. This research offers a precious understanding of using natural fibers as strengthening additives in polyester composites, demonstrating their flexible perspective for many uses. The discoveries present hopeful possibilities for additional examination and progression in the area of composite materials, consequently advancing the development of sustainable materials.

The research proposes a hybrid algorithm model that combines model-driven and data-driven approaches for the direct application of bridge health monitoring technology in bridge management. This comprehensive study encompasses a series of analytical techniques and methodologies to build a multi-objective optimization model for bridge performance assessment and prediction. It focuses on the processing of multi-source heterogeneous data, selection of key sub-parameters using Principal Component Analysis (PCA), enhanced K-means clustering analysis, determination of structural component target thresholds, time-dependent survival probability analysis, regression fitting, and timing prediction of the bridge system for both the components of double-layer truss arch bridge and the bridge system. The initial phase of the study concentrates on the diversification and decentralization of monitored data from various sources, integrating and cleaning data obtained from different sources to ensure data quality and consistency. PCA technique is applied to identify key sub-parameters that have significant impacts on the performance of structural components. Enhanced K-means clustering analysis is carried out to effectively group and classify the identified key sub-parameters. Numerical simulations, including structural nonlinear analysis, are conducted to determine the target thresholds of bridge structure, providing important benchmarks for performance evaluation. Finally, a multi-parameter regression model is used to evaluate and update the performance of the bridge structure, taking into account survival probability (using the Kaplan-Meier method), maintenance history, and material deterioration to estimate the most critical time for the bridge system. A case study is conducted to validate the suggested comprehensive algorithms for a double-layer truss arch combination bridge, which contributes to enhancing performance evaluation and predicting the most critical time for structural components and the bridge system in the bridge management and maintenance practices. It should not be ignored that, the accuracy and reasonability of bridge structure system performance evaluation and prediction depend largely on the selection of target thresholds.

The purpose of this study is to investigate the annual degradation rates of photovoltaic (PV) systems composed of PV modules based on recent crystalline silicon (c-Si) PV technologies. We investigated the annual degradation rates of four PV systems composed of different c-Si PV technologies, comprising p-type multi-crystalline silicon with a passivated emitter rear cell, n-type silicon heterojunction, p-type single-crystalline silicon with an aluminum back surface field, and n-type single-crystalline silicon solar cell technologies. These systems were located in Gunma Prefecture in Japan and were measured over six years. Furthermore, the effects of soiling on the annual degradation rates of these PV systems were examined by partially surface cleaning the PV arrays two times. The results obtained indicate that the apparent annual degradation rates of the PV strings before surface cleaning were 0.8, 1.6, 1.4, and 1.2%/year, respectively, because of optical losses due to dust particles. However, the inherent annual degradation rates of the PV strings after surface cleaning were 0.1, 0.6, 0.0, and 0.3%/year, respectively. These low degradation rates indicate that the PV systems composed of the recent c-Si PV technologies all offered reasonably stable performance that was reduced by 3.6, 5.5, 7.3, and 4.8%, respectively because of the effects of surface soiling, although the surfaces of the PV arrays had been washed by plentiful rainfall under their humid subtropical climatic operating conditions.

The Weizhou X low-permeability reservoir is an offshore reservoir, with a permeability ranging from 0.58×10 -3μm 2 to 470.05×10 -3μm 2, showing strong heterogeneity. In the subsequent water injection development, good results were not always obtained. The main problem was that during the water injection process, the injection pressure increased significantly, resulting in low water injection volume and low water injection efficiency, which could not maintain long-term effective effects on production. Improvement, it is difficult to replenish energy in the formation. Through the analysis of pore-throat structure, water quality compatibility and sensitivity, it is clear that pore-throat blockage is the main reason for low water injection efficiency. Aiming at the present situation that the scaling matter is mainly calcium carbonate, a solution to soil acidification and plugging removal was proposed, and the water injection damage of the actual reservoir was simulated. The indoor acidification experiment was carried out, which showed that the effect of acidification on the transformation of the reservoir was good, and the average rate of transformation is 129.21%. Suggestions are put forward for the effective development of Weizhou X low-permeability reservoirs, the economic benefits of development are improved, and guidance is given for the enhanced injection measures of low-permeability oilfields.

A probabilistic limit equilibrium framework combining empirical load transfer factor and anisotropy of soil cohesion is developed to conduct pile-reinforced slope reliability analysis. The anisotropy of soil cohesion is determined conditioned on that the thrust force direction is parallel to the major principal direction and it is easily combined with load transfer factor, which are related with soil parameters, and pile parameters. The proposed method is illustrated against a homogeneous soil slope. The sensitivity studies of pile parameters on FS (calculated at respective means of soil parameters) and β demonstrated that the anisotropy of soil cohesion tends to pose significant effect on reliability index β than on FS. The effect of anisotropy of soil cohesion on FS is found to be slightly different under different pile locations, whereas its effect on β is observed to be least if piles are drilled at the middle part of slope and more significant effect is observed when piles are drilled at the lower and upper part of slope. The plots from the sensitivity studies provide an alternative tool for pile designs aiming at the target reliability index β. The proposed method contributes to the pile-reinforced slope stability within limit equilibrium framework.

The lossless video coding framework based on HEVC is consisted of prediction and entropy coding, which directly determine the lossless coding efficiency. The initial residuals with large absolute values are directly coded by the lossy coefficient coding techniques in HEVC, which may compromise the lossless coding efficiency. In this paper, an optimized scheme based on transformation and quantization techniques for the HEVC Intra lossless coding is proposed as an additional mode. In the proposed scheme, an initial residual block is divided into two parts: the coefficient block and the second residual block. The coefficient block is derived by the lossy transformation and quantization technics in HEVC. The second residual block is made up with residuals of small absolute values. Both the coefficient block and the second residual block can be efficiently coded by the existing coefficient coding scheme in HEVC. Rate-distortion optimization is employed to choose between the proposed scheme and the transform bypass scheme to achieve the best coding performance for each block. The proposed scheme is implemented into the HM 12.1 software. Experimental results show that the proposed scheme achieves 3.36 percent bit-rate saving on average and up to 12.29 percent compared with the HEVC lossless coding under the Intra main configuration.

In recent years, penetration testing (pen-testing) has emerged as a crucial process for evaluating the security level of network infrastructures by simulating real-world cyber-attacks. Automating pen-testing through reinforcement learning (RL) facilitates more frequent assessments, minimizes human effort, and enhances scalability. However, real-world pen-testing tasks often involve incomplete knowledge of the target network system. Effectively managing the intrinsic uncertainties via partially observable Markov decision processes (POMDPs) constitutes a persistent challenge within the realm of pen-testing. Furthermore, RL agents are compelled to formulate intricate strategies to contend with the challenges posed by partially observable environments, thereby engendering augmented computational and temporal expenditures. To address these issues, this study introduces EPPTA (Efficient POMDP-Driven Penetration Testing Agent), an agent built on an asynchronous RL framework, designed for conducting pen-testing tasks within partially observable environments. We incorporate an implicit belief module in EPPTA, grounded on the belief update formula of the traditional POMDP model, which represents the agent’s probabilistic estimation of the current environment state. Furthermore, by integrating the algorithm with the high-performance RL framework, Sample Factory, EPPTA significantly reduces convergence time compared to existing pen-testing methods, resulting in an approximately 20-fold acceleration. Empirical results across various pen-testing scenarios validate EPPTA’s superior task reward performance and enhanced scalability, providing substantial support for efficient and advanced evaluation of network infrastructure security.

The increasing number of private cars, public transportation vehicles, and pedestrians, as well as the absence of adequate space for these ground amenities, are the primary causes of traffic congestion and accidents in the Kathmandu Valley. Investigations have indicated that the Kathmandu Valley has the greatest traffic accidents despite the heavy presence of government and its agencies there. Most teens and young adults suffer injuries while using motor vehicles. The study’s primary objective is to foresee and prevent such complications by planning for sufficient subsurface infrastructure for the Kathmandu valley’s transportation network. Overlying pressure, lateral earth pressure, live load, uplift pressure, and live surcharge are some of the forces acting on the tunnel, creating unique stress and moment zones. The tunnel meets the following geometric requirements: a) each of the tunnel’s two cells has a clear span of 10 meters and a clear height of 5.5 meters. The side walls, inner walls, top slab, and bottom slab are all 700 mm thick. Soil has built up to a height of 4m over the tunnel’s roof. Construction sequencing, the application of various loads during construction, and expected service life are all taken into account during the design process. Analytical and computer software (SAP 2000) are both used in the tunnel segment’s analysis. Furthermore, the designed tunnel has been evaluated for stability, considering the deflection and shear resistance. The analysis indicates that the tunnel meets the stability requirements, as the checks performed for deflection produce satisfactory results. This implies that the structure is capable of withstanding the applied forces without excessive deflection.

This paper proposes a hierarchical distributed voltage control (HDVC) scheme for active distribution networks (ADNs) with high penetration of photovoltaics based on distributed model predictive control (DMPC) and alternating direction method of multipliers (ADMM). The reactive power outputs of several photovoltaic clusters (PVCs) and photovoltaic (PV) units within each PVC are optimally coordinated to keep PV terminal voltages and the voltages of all critical buses of ADNs within the feasible range and mitigate voltage fluctuations. In the ADN layer, a distributed reactive power control scheme based on DMPC is designed for the PVC, which regulates the voltages of all critical buses to be closed to the rated value and mitigates the reactive power variations. In the PVC layer, the reactive power outputs of PV units are optimized based on ADMM to minimize the voltage deviation of each PV terminal and track the reactive power reference from the PVC control. The proposed HDVC scheme requires communication only between neighboring PVC controller, while each PV controller only communicates with the corresponding PVC controller. This regulates the voltages in a completely decentralized manner and effectively reduces the computation burden of the PVC and PV controllers. A modified Finnish distribution network with 10 PVCs was used to validate the control performance of the proposed HDVC scheme.