Search Results (46)

Building on our previous multi-configuration Dirac–Hartree–Fock (MCDHF) computational strategies tailored for the hyperfine structure (HFS) of low-lying levels in one-valence electron Sr II and Ba II ions and in two-valence electrons in a Ba I atom, we successfully extend these methodologies along the alkaline-earth elements to the lighter Ca II and heavier Ra I–II ions. MCDHF-recommended HFS constants, along with their uncertainty estimates, are reported for the first time and critically discussed. Where applicable, the Bohr–Weisskopf correction is applied to the HFS constants, and its effects are analyzed. This is particularly valuable for cases where no measurement is available such as for the [Rn]${6d }^2{D}_{3/2,5/2}$ levels in ^223,225Ra II, for the [Rn]${7s6d }^3{D}_{1,2,3}$ and ¹$D_2$ levels in ²²³Ra I, for the [Rn]$7s{6d }^3{D}_{2,3}$ and ${}^{1}D_2$ levels in ²²³Ra I, and for the [Rn]$7s{7p }^3{P}_2^o$ level in ²²⁵Ra I. In all cases, our MCDHF values agree with the ones found in the literature within our error bars. For the ${}^{2}D_{5/2}$ levels in Ca II and Ra II, the discrepancies with the experiment observed in Sr II and Ba II for the HFS A constant are not seen. Full article

The rapid growth of express packaging waste (EPW) is creating increasing challenges for urban waste management and high-quality resource recovery, while reliable automated sorting remains difficult because of heterogeneous materials, deformable packaging, random stacking, and frequent partial occlusion. This study develops a system-oriented RGB-D sensing framework to improve the reliability of EPW sorting in conveyor-belt recycling operations. A synchronized and spatially registered RGB-D paired dataset, MEPWaste, was constructed containing 4528 paired samples (9056 RGB/depth images) from 10 representative categories of inner and outer packaging under multiple levels of stacking and occlusion. Based on this dataset, a multimodal detection framework was designed to improve feature reliability within each modality, reinforce spatial consistency between modalities, and enhance detection stability in densely stacked scenes with fragmented visible evidence. The proposed framework achieved 89.1% ${mAP}_{50}$ and 69.3% ${mAP}_{50:95}$, exceeding the RGB-only model by 5.3 and 5.8 percentage points, respectively, and the RGB-D baseline by 2.7 and 3.4 percentage points, with recall reaching 85.1%. A closed-loop sensing–inference–execution pipeline integrating synchronized RGB-D acquisition, real-time detection, robotic grasping, and PLC-based control was further implemented to examine engineering feasibility. Overall, the study provides a practical technical pathway for improving EPW sorting reliability and supporting intelligent resource recovery in waste management systems, with potential applicability to green campus management scenarios characterized by high-frequency parcel consumption and concentrated packaging waste generation. Full article

Total, momentum-transfer, and differential cross sections, together with spin-polarization (Sherman) functions, are reported for elastic scattering of low-energy electrons from neutral strontium atoms over the energy range 0.001–15 eV. The calculations are performed within a fully relativistic Dirac framework for the continuum states. The target structure is described using multi-configuration Dirac–Hartree–Fock wavefunctions obtained with the GRASP2018 package, while continuum orbitals are generated using the recently developed GRASPC extension. Long-range target polarization effects are incorporated using a dipole model potential, and exchange interactions are treated explicitly for the large and small components of the continuum wavefunctions. Particular attention is given to the ultralow-energy regime, where reliable cross section data for Sr remain limited. The calculated total cross section exhibits a broad maximum near 1 eV, while the momentum-transfer cross section shows a shallow minimum near 0.05–0.06 eV. The differential cross sections are in good agreement with earlier static-exchange-plus-polarization calculations over much of the 1–5 eV range, whereas at lower energies, visible differences appear, especially at forward angles where the results are most sensitive to the polarization interaction. In the ultralow-energy region, the present differential cross sections remain smooth and show no indication of additional low-lying shape resonances within the adopted model. The calculated Sherman functions follow the general trends of earlier theoretical studies at higher energies and decrease rapidly in the sub-eV range. Overall, the present results provide a consistent relativistic dataset for elastic e–Sr scattering at low energies, with emphasis on the near-threshold region. Full article

A developed method, based on the stationary second-order Rayleigh–Schrödinger many-body perturbation theory in an irreducible tensorial form, allows us to determine the most important core–valence, core, core–core, and valence–valence correlations for any atom or ion with an arbitrary number of valence and core electrons. This paper presents the Feynman diagrams that describe these correlations. Additionally, it provides the rules for obtaining algebraic expressions in an irreducible tensorial form for any Feynman diagram coming from second-order many-body perturbation theory. Whereas some types of the valence–valence and core–valence correlations are described by the three-particle Feynman diagrams, additional developments to calculate the spin-angular parts of these diagrams have been made to the program library librang of the Grasp2018 As an example of the application of the developed method, the atomic calculations of the energy level structure and transition data for Ar II are presented. Full article

The Rci-Q package is an extension to the Grasp2018 suite, improving the model of estimating the quantum electrodynamics corrections to the energy levels. The Flambaum–Ginges radiative potential method is used to estimate the leading self-energy correction to electron energy in many electron atoms. The new fitting prefactors to parameterize radiative potential are presented. The correction to self-energy originating from finite nucleus size is included. The Wichmann–Kroll part of the vacuum polarization potential is also implemented. Full article

Using the Multiconfiguration Dirac–Hartree–Fock method as implemented in the General Relativistic Atomic Structure Package, the magnetic dipole and electric quadrupole hyperfine structure constants were determined for the ground and first excited levels of ^135,137Ba II isotopes, as well as for ¹³⁷Ba I and ⁸⁷Sr II, to assess the robustness of the developed model. This study builds upon and extends previous investigations by examining the levels involved in resonance lines, with the aim of resolving persistent discrepancies in the hyperfine structure of ¹³⁷Ba II and ⁸⁷Sr II. New code developments such as the use of natural orbitals, as well as the addition of polarization effects and Configuration State Function Generators, as implemented in GRASPG, were tested for these heavy elements. The developed strategy allowed us to achieve encouraging results that satisfactorily agree with experiments for all studied levels but ${}^{2}D_{5/2}$ in the ¹³⁷Ba II isotope. This disagreement was also observed in ¹³⁵Ba II isotope as well as in ⁸⁷Sr II. With two valence electrons, ¹³⁷Ba I is definitely more complex, requiring a multireference approach. Even with the latter, the theory–observation disagreement observed for the hyperfine structure of the low-lying levels remains large in comparison with the alkali-like systems. Possible ongoing developments to remediate this issue are discussed in the conclusions. Full article

This paper presents the development of an autonomous grasping mechanism for drone-based parcel delivery systems towards developing capabilities for in-flight package transfer. The approach integrates a mechanical gripper fitted with sensors and a pose estimation method for parcels, all coordinated through a hybrid Model Predictive Control (MPC) architecture. The gripper’s mechanical structure and prototype are developed using 3D printing technology for both the main framework and gear components. A hybrid dynamical model is formulated that integrates the gripper mechanics with simplified drone dynamics, capturing distinct operational phases including package acquisition, transport, and release. The hybrid MPC framework computes reference trajectories for both the gripper arm configuration and the drone’s spatial path toward designated target positions. Experimental validation is conducted using the operational gripper prototype and pose estimation system, while drone behavior is represented through simulation. Full article

Shipborne UAV-assisted dock is an important way to recover unmanned systems for remote water surface low-altitude detection. The lack of resisting deck disturbances capability for UAV autonomous landing in dynamic dock stations has led to the inability of traditional hovering recovery methods for single UAV guidance and flight attitude control systems to meet the growing demand for landing assistance. In this work, we present a shipborne manipulator arm designed to grasp drones that use low-altitude visual servo technology for landing on the water surface. The shipborne manipulator arm is fabricated as a key component of a seaplane drone dock comprising a ship-type embedded drone storage, a packaged helistop for power transfer and UAV recovery, and a multi-degree-of-freedom arm integrated with multi-source information sensors for the treatment of air-to-water-related airplane crashes. Dynamic model tests have demonstrated that the end-effector of the shipborne manipulator arm stabilizes and performs optimally for water surface disturbances. A down-to-top grasp docking paradigm for a UAV-assisted perching on a shipborne helistop that enables the charging components of the station system to be equipped automatically to ensure that the drone performs its mission in the best condition is also presented. The surface grasp experiments have verified the efficacy of this grasp paradigm when compared to the traditional autonomous landing method. Full article

Handling delicate agricultural products, such as tomatoes, requires careful attention from workers during harvesting, sorting, and packaging processes. This labor-intensive approach is often inefficient and susceptible to human error. A potential solution to improve efficiency is the development of automated systems capable of replacing manual labor. However, such systems face significant challenges due to the irregular shapes and fragility of these products, requiring specialized adaptable and soft gripping mechanisms. In this context, this paper introduces a parametric design methodology for 3D-printed flexible fingers in soft grippers, tailored for agricultural applications. The approach was tested in a case study that targeted soft agricultural products with diameters between 45 and 75 mm. Three finger topologies were modeled and compared to identify an optimal configuration. A prototype was then developed using 3D printing with Z-SemiFlex. Experimental tests confirmed that the prototype could grasp different fruits reliably and without surface damage. It achieved an Average Precision (AP) of 87.5% for tomatoes and 92.5% for mandarins across 80 trials. These results validate the feasibility of the proposed design methodology for fingers in soft grippers. Full article

Tactile sensation is a crucial sensory pathway for humans to acquire information from the environment, and vibration feedback is one form of tactile feedback, offering advantages such as low cost, ease of integration, and high comfort. Avoiding mechanical crosstalk without changing the spacing between vibration units is a significant challenge in the design of haptic interfaces. This work focuses on the joint optimization design of vibration source characteristics and packaging materials of vibration units. From a theoretical modeling perspective, we explore the correlation between material properties and the amplitude of vibrations generated on the skin surface. A three-layer vibration unit optimization design scheme using a pogo pin structure is thus proposed. Parameters are optimized through finite element analysis, and experimental results prove that the three-layer vibration unit with pogo pins has amplitude modulation capabilities, laying the foundation for the design of array-based vibration tactile feedback interfaces and human-inspired grasp control. Full article

The deep-water area of the Qiongdongnan basin is currently a hot topic for exploration. The discovery of gas fields in the Baodao sag confirms its abundant oil and gas resources and potential, making it of significant economic and strategic importance. The complexity of sedimentary structural evolution within the Baodao sag makes the process of oil and gas accumulation in the area extremely complex, and the law of natural gas enrichment is difficult to grasp, resulting in unclear exploration directions. Therefore, this study focuses on the third member of the Lingshui Formation in the Paleogene of the Baodao sag. Based on the abundant thin section, scanning electron microscopy, 3D seismic and geochemical analysis data in the area, through analyzing the density of natural gas, the proportion of hydrocarbon and non-hydrocarbon components, the dryness coefficient carbon, and the isotopic characteristics, combined with the deep natural gas genesis discrimination chart, the types and genesis types of natural gas and organic matter in the sag are clarified. In addition, combined with the package and BasinMod 2009 software, the filling period and reservoir-filling process were clarified and restored. At the same time, the reservoir formation characteristics of the different fault-step zones inside the sag were dissected and the primary and secondary migration of natural gas were analyzed in order to clarify the types and characteristics of different fault-step zone transport systems. Finally, the research findings indicate that there are two reservoir formation modes developed within the depression, as follows: “multiple hydrocarbon generation and control sources—continuous vertical control of large faults—lateral sand body convergence (T + Z-type transport)—multiple cap layer closure” and “mixed-source hydrocarbon supply—continuous vertical control of large faults—short lateral sand body convergence (Z-type transport)—multiple cap layer closure”, providing an important basis for the next exploration of the basin. Full article

The transition towards a circular economy, as outlined in the European Union’s Green Deal, requires the development of industries dedicated to recycling and material recovery. Within this context, the recycling of plastic and packaging waste is critical in reducing greenhouse gas emissions. Traditional pick-and-place systems encounter significant challenges when applied to heterogeneous waste streams due to the variability in shape, weight, and material properties of the processed materials. To address these challenges, this research proposes a heuristic to optimize the use of multiple gripper systems within a multirobot multigripper sorting setup, with the goal of both maximizing sorting efficiency and recovery rates in PPW recycling. Therefore, the performance of grippers on specific PPW objects, materials and shapes is quantitatively assessed by measuring the grasp efficiency. This grasp efficiency is incorporated into the proposed scheduling heuristic and used to assign the PPW objects to the different available robots, taking into account the position of the object with respect to the robot and the gripper installed on the robot. This heuristic is then evaluated and benchmarked through simulations considering the sorting system design and the waste stream composition based on a real-world portable robotic material recycling facility. The findings demonstrate substantial improvements in picking efficiency of up to 3.6% and pick rates up to 37.5%, underscoring the potential of advanced heuristic algorithms in robotic waste sorting systems. Future work will focus on refining gripper designs and exploring predictive algorithms to further enhance grasp success rates. Full article

When considering the chronological order of product use, package design is mainly related to forming the anticipated UX, which predicts and imagines the experience gained from interacting with the product. However, in previous research, no method has been established for specifically evaluating the anticipated UX, and there is little knowledge about the relationship between packaging design and anticipated UX. This research aimed to examine a method to investigate the anticipated UX that users gain from packaging design in an exploratory and qualitative manner. We adopted the evaluation grid method, an interview and analysis technique that can clarify the evaluation structure that people have for the target of evaluation, and examined the structure of the design elements of the packaging and the appeal and sense of expectation that can be gained from them. We selected 20 products from each of two product groups for evaluation as examples: boxed flour confections and sunscreen. Ten people participated in the grid evaluation method survey for each product, and an evaluation structure diagram was created to summarize the results for each group of products. For flour confections packaging, the focus was on whether people could imagine what the taste would be like, and for sunscreen packaging, the focus was on concepts related to the performance and effectiveness of the sunscreen. These results show that it is possible to grasp the anticipated UX based on the user’s words using the evaluation grid method. The results of this research will contribute to establishing a method for examining anticipated UX and will be useful for achieving packaging design that enhances UX. In addition, the findings of the analysis cases presented in this research can be used to improve UX in the packaging of sweets and sunscreen. Full article

This paper aims to address the challenge of precise robotic grasping of molecular sieve drying bags during automated packaging by proposing a six-dimensional (6D) pose estimation method based on an red green blue-depth (RGB-D) camera. The method consists of three components: point cloud pre-segmentation, target extraction, and pose estimation. A minimum bounding box-based pre-segmentation method was designed to minimize the impact of packaging wrinkles and skirt curling. Orientation filtering combined with Euclidean clustering and Principal Component Analysis (PCA)-based iterative segmentation was employed to accurately extract the target body. Lastly, a multi-target feature fusion method was applied for pose estimation to compute an accurate grasping pose. To validate the effectiveness of the proposed method, 102 sets of experiments were conducted and compared with classical methods such as Fast Point Feature Histograms (FPFH) and Point Pair Features (PPF). The results showed that the proposed method achieved a recognition rate of 99.02%, processing time of 2 s, pose error rate of 1.31%, and spatial position error of 3.278 mm, significantly outperforming the comparative methods. These findings demonstrated the effectiveness of the method in addressing the issue of accurate 6D pose estimation of molecular sieve drying bags, with potential for future applications to other complex-shaped objects. Full article

Multirotor drones are widely used in fields such as environmental monitoring, agricultural inspection, and package delivery, but they still face numerous challenges in durability and aerial operation capabilities. To address these issues, this paper presents a biomimetic leg-claw mechanism (LCM) inspired by the biomechanics of birds. The claw of the LCM adopts a bistable gripper design that can rapidly close through external impact or actively close via the coordination of internal mechanisms. Additionally, its foldable, parallelogram-shaped legs bend under external forces, stretching the main tendon. A ratchet and pawl mechanism at the knee joint locks the leg in the bent position, thereby enhancing the gripping force of the claw. This paper calculates and experimentally verifies the degrees of freedom in different states, the forces required to open and close the gripper, the application scenarios of active and passive grasping, and the maximum load capacity of the mechanism. Furthermore, perching experiments demonstrate that the LCM enables the drone to perch stably on objects of varying diameters. Full article