Search Results (98)

Deep Research Agents (DRAs) generate detailed literature surveys but often suffer from hallucinations and inconsistent structures. Existing evaluation methods face significant limitations. Human evaluation is time-consuming and requires domain expertise. Meanwhile, current LLM judges struggle with long reports due to context limits and the inability to verify source reliability. To address this, we propose Deep-Research Eval. This framework standardizes the page as the basic unit for evaluation. It features an adaptive scoring system that assesses the logical quality of each page. Furthermore, it employs Paged-RAG with a constructible reference database to verify facts against specific evidence. Experiments on five agents show that our method effectively identifies errors. It achieves a strong correlation with human judgment, reaching a Composite Consistency Index (CCI) of 0.7585, an absolute increase of 0.4588 over baselines. Additionally, the Paged-RAG module improves factual verification accuracy, increasing the QA-F1 score by up to 6.9 times compared to standard retrieval methods. This work offers a scalable and practical approach for assessing AI-generated academic content. Full article

Large flange shafts are the core load-bearing and connecting components of high-end equipment, and their welding multi-physical fields directly affect the quality and service safety of the components. Traditional experiments and finite element methods suffer from long cycles and low efficiency, which can hardly meet the demand for rapid prediction. Aiming at the fast and accurate prediction of welding temperature, deformation and residual stress, this study combines thermal–mechanical coupled finite element simulation with machine learning to construct and compare a variety of prediction models. A dataset is built based on simulation data from 100 groups of process parameters. Overfitting is reduced through strategies including early stopping and dropout, and models such as MLP, RF, RBF-SVR, TabNet, XGBoost, and FT-Transformer are established and verified through 10-fold cross-validation. The results show that the MLP model performs best in the prediction of temperature, deformation and residual stress, and is in good agreement with the simulation values. The prediction errors of the peak temperature of the weld and base metal are below 5%, and the errors of deformation and residual stress are controlled within 10%. The average error of peak residual stress is about 6 MPa, and the deviation of most samples is less than 5 MPa. The RF model ranks second in accuracy, with an average error of about 6.5 MPa for peak residual stress, showing a satisfactory interpretability and engineering applicability. RBF-SVR and TabNet can meet basic prediction requirements. Under the small-sample condition in this work, XGBoost and FT-Transformer present relatively large errors and a weak generalization ability, making it difficult to achieve high-precision prediction. The MLP model established in this paper can effectively reproduce the evolution of welding multi-physical fields and supports the rapid prediction and process optimization of large flange shaft welding. The generalization ability and practical performance of the model can be further improved by expanding the dataset and experimental verification in the future. Full article

Although computational thinking (CT) has attracted researchers’ and educators’ interest for the last 20 years, resulting in new educational approaches and reformation of curricula, more research work needs to be performed, especially in the field of CT assessment. Taking this need into consideration, this article describes the development of a new CT assessment tool. The DACT CT assessment tool is developed based on CT literature, taking into consideration six basic CT dimensions. Initially, 90 CT assessment tasks are created, which are examined and reformed through a pilot study. The main research consists of an extensive study (521 students), which has resulted in the construction of the DACT CT assessment tool through continuous monitoring of Cronbach’s α, consisting of 36 final tasks. DACT is disengaged from programming, does not require a specific programming language as it uses its own micro-world, is cross-platform and can be administered online or in paper format mode, supported by an administering protocol. This article also discusses the validation process of the DACT and argues on several validation checks, such as face validity, criterion validity and concurrent validity. This work has the ambition to provide a new, useful CT assessment tool to the scientific community. Full article

Digital twin technology puts forward higher requirements on the real-time performance of simulations. In order to realize the online simulation of the heat treatment process, a transient temperature field-microstructure field coupling calculation method based on the reduced-order model was constructed. This mathematical model was applied to the online simulation of the end-quenching treatment of 42CrMo steel with complex time-varying water spray. The results show that the utilization of a 10th-order reduced-order model diminishes the total computation time from 1 h to 3.4 s, with a reduction in storage requirements by a factor of 610. The calculation accuracy of the reduced-order model is 99.2%, which satisfies the requirements of real-time online simulation. A framework for the heat treatment digital twin system has been proposed and an online simulation platform for end-quenching treatment was developed. The single-step calculation time for the proposed platform is 0.4 s. The online simulation temperature is basically consistent with the measured temperature results. This work provides novel avenues for fast calculation and real-time control of the heat treatment process. Full article

Systems with large physical size such as wind turbines, aircraft, and ships are dominated by the inertia of the flow. In conventional experimental facilities, a reduction in scale is required, which can introduce viscous effects that are not present at full size. However, if the wind tunnel is operated with a heavy gas, the reduction in scale can be counteracted by an increase in density, and the flow that exists at full size can be recreated accurately. This work describes the design, construction, and basic flow characterization of a heavy gas wind tunnel facility, known as the Compressed Air Wind Tunnel (CAWT), that utilizes pressurized air as the working fluid at pressures up to 35 bar. The tunnel was designed to accommodate relatively large models inside the 1.04 meter-diameter test section while having improved optical access compared to existing facilities of this type. A series of flow characterization tasks were carried out on the completed facility, including quantifying the turbulence intensity and flow uniformity in the tunnel test section. Measurements showed a maximum turbulence intensity of 0.46% and an average of 0.22% across all conditions and locations tested. The maximum velocity non-uniformity between four locations in the test section was 0.36%, which occurred at the lowest tested wind speed of 2.4 m/s. The average non-uniformity across all tested conditions was less than 0.093%. Mapping the facility operating space has now enabled ongoing work examining rotorcraft, marine propeller, and wind turbine performance and wake development with the aim of answering long-standing questions regarding how the fluid dynamics depend on scale or Reynolds number effects. Full article

Limitations associated with traditional automation approaches within manufacturing have driven the pursuit of more flexible and intelligent robot guidance methods. One promising development in this area is the integration of external multitarget six degrees of freedom (6 DoF) distributed large-volume metrology (DLVM) into the control loop. Although multiple standards exist across dimensional metrology, motion tracking, indoor positioning, robot guidance, and machine tool accuracy, there is no harmonised, technology-agnostic standard that fully encompasses the unique challenges of 6 DoF DLVM systems for dynamic applications. This work identifies key gaps in the current standards’ landscape and presents a technology-agnostic candidate test methodology intended to support future standardisation of dynamic DLVM performance evaluation. The method provides a metrologically grounded spatial reference path and a temporal alignment strategy so that position and orientation errors can be reported in the intrinsic coordinates of the path. The paper covers the basic principle of the test, artefact construction, synchronisation strategies, preliminary error modelling, and a baseline uncertainty approach, and reports representative results from initial prototype trials on a multi-nodal distance-camera DLVM system. The prototype results demonstrate feasibility and highlight temporal sampling and traceable timing as current limiting factors for fully deconvolving latency and pose error; these aspects are therefore positioned as instrumentation requirements and the focus of ongoing work. Full article

Agricultural facilities in tropical regions such as Hainan China face dual challenges from summer typhoons and occasional winter cold waves. Traditional greenhouses are generally constructed at a low height to resist typhoons, which hinders mechanized operations, while the use of insect-proof screens compromises thermal insulation. To resolve these contradictions, this study designs a typhoon-resistant multi-span greenhouse with an elevatable roof. Its core innovation lies in adopting a mechatronic steel cable system to achieve synchronized elevation of single-span roof surfaces. During daily operations, the roof is elevated to facilitate mechanized field operations; during typhoons or cold waves, the roof is lowered to the ground, reducing wind load impact and improving thermal insulation performance. The greenhouse’s elevating system incorporates multiple safety functions, including bidirectional self-locking and overload protection. Structural calculations using PKPM 2010 software show that under two working conditions—roof elevated (basic wind pressure of 0.45 kN/m²) and roof lowered (basic wind pressure of 1.30 kN/m²)—all indicators meet the requirements of relevant codes. Compared with an ordinary circular-arch greenhouse of the same size and under the same loads, the steel consumption of the standard single-span frame (6 m span, 4 m bay width) of the Elevating Greenhouse is only 67.38 kg, a 35% reduction compared with 103.58 kg for the ordinary greenhouse, significantly reducing construction costs. This study provides an innovative, safe, and economical technical solution for protected agriculture in tropical regions. Full article

The pendant drop method is often used to determine the surface tension of liquids. However, in the process of calculating surface tension, corresponding density data are required, which brings a series of problems to the determination of the surface tension of high-temperature slag, especially. So far, there have been few reports on determining the two properties of density and surface tension by the pendant drop method in a single experiment. In this work, CaO–50% Al₂O₃ slag was taken as the research object, a novel ring-shaped-pendant drop-forming device constructed with Pt–10% Ir alloy was employed, and the outer diameter of the alloy ring at experimental temperatures was determined as a reference scale by pixel analyses of images. The density and surface tension of the slag within the range of 1450 to 1650 °C were simultaneously determined under heating and cooling modes, respectively, and the effect of slag mass on measurement results was also investigated. The results show that the measurement mode (heating or cooling) has little effect under experimental conditions, whereas the slag mass has a certain effect when it is small. The average density and surface tension values obtained both decrease with increasing temperature, and the temperature coefficients are −3.406 × 10⁻⁴ g/(cm³⋅°C) and −4.2 × 10⁻² mN/(m⋅°C), respectively. The density and surface tension of the slag at 1550 °C are 2.836 g/cm³ and 624 mN/m, respectively. In addition, the combined standard uncertainties of the measured density and surface tension are 0.01 g/cm³ and 4 mN/m, respectively. The density and surface tension values are basically consistent with literature data. This work can provide an experimental basis for the development of a pendant drop method used to determine the density and surface tension properties of molten slag. Full article

In order to meet the dual requirements of low-energy heating and flexible operation, a comprehensive heating system with multi-mode and wide-load capabilities was constructed, incorporating a heat pump, a back-pressure turbine, and two 350 MW coal-fired condensing units. Based on the heat transfer characteristics of this system, the simulation model of this comprehensive thermal system was constructed through a commercial software (EBSILON). A dynamic coal consumption prediction method based on the non-equilibrium state parameters was first proposed, which was primarily designed for system operation optimization. Subsequently, the converted load and load change rate were integrated into the dynamic correction model to refine prediction accuracy. The results showed that while basic coal consumption primarily correlates with heat load and electricity load, dynamic coal consumption is influenced by both the converted load and the load change rate. Based on this, the three-dimensional surface plot of converted load, load charge rate, and dynamic coal consumption offset coefficient was calculated. Then, the accuracy of the prediction model was verified by the variable working condition parameter group, and its reliability was confirmed. Further, by developing online software, theoretical guidance for industrial production was realized. In a heating season case study, it was demonstrated the prediction method can effectively reflect the dynamic parameter deviation in the system, with the annual coal saving being able to reach 841.5 tons. It is expected to provide theoretical guidance for the research on multi-heat sources heating distribution and operation parameter optimization. Full article

Evaluating wood’s natural durability is essential when establishing the level of protection that is required depending on the end use to extend its service life. Natural durability is defined as the intrinsic resistance of wood against the attack of destructive organisms. There are standardized methods for estimating a durability value. In Europe, the EN 350:2016 standard is responsible for establishing the basic guidelines, as well as the necessary tests to determine this value. This standard applies to commercial wood, both native and imported, and helps to improve and obtain better construction applications depending on the final use. This work aimed to study the natural durability of Quercus pyrenaica Wild. against Basidiomycetes (Coniophora puteana (Schumacher ex Fries) Karsten and Trametes versicolor (Linnaeus) Quélet) and termites (Reticulitermes grassei Clément). The standards applied were EN 113-2:2021 and EN 117:2023. The heartwood of the Quercus pyrenaica is highly durable against both xylophages basidiomycetes and subterranean termites. The sapwood is moderately durable against Coniophora puteana, slightly durable-not durable against Trametes versicolor, and moderately durable against termites. These results open the door for commercialization of this species, and it is expected to be included in EN 350:2016, where Q. pyrenaica is not included. Full article

Pressure on fresh water resources has been aggravated in recent decades, basically due to population growth, rapid urbanization, and global warming. Integrated engineering solutions and the circular economy, considering the urban water cycle as a whole, are becoming fundamental, particularly in arid and semi-arid regions under permanent or recurrent hydric deficit. This study aims to develop and present an integrated engineering solution for water supply, wastewater collection, and treated wastewater reuse for landscape irrigation in a large, topographically complex, and arid to semi-arid coastal urban region at the south of Santiago Island, Cape Verde. The region is one of the driest and most arid of the Island, with a current average annual precipitation between about 100 and 200 mm, and has very limited underground water resources. The main study area, with about 600 ha, has altitudes ranging from values close to sea level up to about 115 m and has several topographic difficulties, including several relatively rugged zones. The devised water supply system considers four altimetric distribution levels, three main reservoirs connected to each other by a serial system of pipelines with successive pumping, a fourth downstream reservoir for pressure balance in one of the levels, and desalinated water as the source. The sanitary sewer pipes of the urbanizations drain to an interceptor system that operates predominantly in open channel flow in a closed pipe. The long interceptor crosses laterally along the coast several very dug valleys in the path to the Praia Wastewater Treatment Plant in the east, and requires several conduits working under pressure for the crossings, either lifting or governed by gravity. The under-pressure pipeline system of recycled water is partially forced and partially ruled by gravity and transports the treated wastewater from the plant in the opposite direction of the interceptor to a natural reservoir or lake located in the region of urbanizations and the main green spaces to be irrigated. The conceived design of the interceptor and recycled water pipeline minimizes the construction and operation costs, maximizing their hydraulic performance. Full article

Taking the leap to the secondary and tertiary generations of the missions to Mars, a comprehensive outline was presented for a cluster of Martian Habitat Units (MHUs) designed for long-term settlements of research crew in Melas Chasma, Valles Marineris, Mars. Unlike initial exploration missions, where primary survival is ensured through basic engineering solutions, this concept targets later-stage missions focused on long-term human presence. Accordingly, the MHUs are designed not only for functionality but also to support the social and cultural well-being of scientific personnel, resulting in larger and more complex structures than those typically proposed for early-stage landings. To address the construction and structural integrity of the MHUs, the current work presents a comprehensive analysis of the feasibility of semi-3D-printed structural systems using in situ material to minimize the cost and engineering effort of logistics and construction of the units. Regolith-based additive manufacturing was utilized as the primary material, and the response of the structure, not only to the gravitational loads but also to those applied from the exterior flow field and wind pressure distributions, was simulated, as well as the considerations regarding the contribution of the extreme interior/exterior pressure differences. The full analyses and structural results are presented and discussed in this manuscript, as well as insights on manufacturing and its feasibility on Mars. The analyses demonstrate the feasibility of constructing the complex architectural requirements of the MHUs and their cost-effectiveness through the use of in situ resources. The manuscript presents an iterative structural optimization process, with results detailed at each step. Structural elements were modeled using FEM-based analysis in Karamba-3D to minimize near-yielding effects such as buckling and excessive displacements. The final structural system was integrated with the architectural design to preserve the intended spatial and functional qualities. Full article

Ball lightning (BL) has been observed for centuries. There are a large number of books, review articles, and original scientific papers devoted to different aspects of the BL phenomenon. Yet, the basic features of this phenomenon have never been explained by known physics. The main problem is the source which could power the dynamics of BL. We advocate the idea that dark matter (DM) in the form of axion quark nuggets (AQNs) made of standard model quarks and gluons (similar to the old idea of Witten’s strangelets) could internally generate the required power. The AQN model was invented long ago without any relation to BL physics. It was invented with a single motivation to explain the observed similarity, ${\Omega }_{\mathrm{DM}}\sim {\Omega }_{\mathrm{visible}}$, between visible and DM components. This relation represents a very generic feature of this framework, not sensitive to any parameters of the construction. However, with the same set of parameters being fixed long ago, this model is capable of addressing the key elements of the BL phenomenology, including the source of the energy powering the BL events. In particular, we argue that the visible size of BL, its typical life time, the frequency of its appearance, etc., are all consistent with the suggested proposal that BL represents a profound manifestation of DM physics represented by AQN objects. In this work, we limit ourselves to the analysis of the thunderstorm-related BL phenomena, though weather-unrelated BL events are also known to occur. We also formulate a number of specific possible tests which can refute or unambiguously substantiate this unorthodox proposal on the nature of BL. Full article

Generating robot behaviors in dynamic real-world situations generally requires the programming of multiple, often redundant degrees of freedom to meet multiple goals governing the desired motions. In this work, we propose a constraint-based controller specification methodology. A novel declarative language is used to combine semantically specialized building blocks into composite controllers. This description is automatically transformed at runtime into an executable form, which can automatically leverage multiple threads to parallelize computations whenever possible. Enabling runtime definition of controller topologies out of declarative descriptions not only reduces the work required to develop such controllers, but it also allows one to dynamically synthesize new controllers based on higher-level task planners or by user interaction through Graphical User Interfaces (GUIs). Our solution adds new functionality to the Robot Operating System (ROS)/ros_control ecosystem, where robot behaviors are typically achieved by deploying single-objective, off-the-shelf controllers for tasks like following joint trajectories, executing interpolated point-to-point motions in Cartesian space, or for basic compliant behaviors. Our proposed constraint-based framework enhances ros_control by providing the means to easily construct composite controllers from existing primary elements using our design language. Building on top of the ros_control infrastructure facilitates the usage of our controller with a wide range of supported robots and enables quick integration with the existing ROS ecosystem. Full article

The a priori procedure (APP) is concerned with determining appropriate sample sizes to ensure that sample statistics to be obtained are likely to be good estimators of corresponding population parameters. Previous researchers have shown how to compute a priori confidence interval means or locations for normal and skew-normal distributions. However, two critical limitations persist in the literature: (1) While numerous skewed models have been proposed, the APP equations for location parameters have only been formally established for the basic skew-normal distributions. (2) Even within this fundamental framework, the APPs for sample size determinations in estimating locations are constructed on samples of specifically dependent observations having multivariate skew-normal distributions jointly. Our work addresses these limitations by extending a priori reasoning to the more comprehensive unified skew-normal (SUN) distribution. The SUN family not only encompasses multiple existing skew-normal models as special cases but also enables broader practical applications through its capacity to model mixed skewness patterns and diverse tail behaviors. In this paper, we establish APP equations for determining the required sample sizes and set up confidence intervals for the location parameter in the one-sample case, as well as for the difference in locations in matched pairs and two independent samples, assuming independent observations from the SUN family. This extension addresses a critical gap in the literature and offers a valuable contribution to the field. Simulation studies support the equations presented, and two applications involve real data sets for illustrations of our main results. Full article