To address the automation of table grape harvesting, a clamping and cutting integrated, four-point flexible end-effector is designed, based on the biological and mechanical characteristics of grapes. The clamping device is validated in regard to force closure requirements using a force spiral. On this basis, a finite element model of the grape pedicel–blade system is established, and dynamic simulations of pedicel cutting are conducted using ANSYS 2021/LS-DYNA. The simulation results indicate that when the pedicel diameter is 10 mm, the maximum shear stress is 1.515 MPa. A kinematic simulation of the clamping device is performed using ADAMS, producing a contact force curve between the end effector’s finger joints and the grape during the clamping process. The simulation results show that the peak contact force of 11 N is lower than the critical rupture force of the grape (24.79 N), satisfying the requirements for flexible, low-damage harvesting. Furthermore, to address the vulnerability of grapes, a contact-force control system is designed, employing a position–speed–torque three-loop control strategy. Pressure sensors integrated into the four clamping fingers provide real-time feedback to adjust the contact force, ensuring precise clamping control. Finally, a physical prototype of the end effector and controller is developed, and harvesting trials are conducted in a vineyard. The harvesting success rate reaches 96.7%, with an average harvesting time of 13.7 s per trial. The grape cluster damage and berry drop rates are 3.2% and 2.8%, respectively, meeting the expected design requirements.

Nanofluids are widely applied in spray cooling, combustion, and coating processes, where nanoparticle dispersion modifies base fluid rheology and influences atomization behavior. Accurate modeling requires computational fluid dynamics (CFD) approaches that capture gas–liquid interactions, nanoparticle transport, and sub-grid effects including interphase momentum exchange, particle collisions, and Brownian motion. This study presents a novel three-phase solver developed in OpenFOAM based on multiphase mixture theory, incorporating the volume of fluid (VOF) method enhanced with isoAdvection for sharp interface reconstruction, adaptive mesh refinement (AMR) for high-resolution atomization, and closures for gravity, buoyancy, centrifugal forces, turbulent and shear-induced diffusion, van der Waals forces, and particle collisions. Nanoparticle rheology is modeled via kinetic theory. Validation was conducted in two stages. Sedimentation simulations for nanoparticle mass fractions of 1–7 wt. % predicted base fluid–nanofluid (B-N) interface and sediment height with maximum relative errors of 2.03% and 3.06%, respectively, and experimental relative standard deviations below 0.93% (B-N interface) and 3.87% (sediment height). Water primary atomization simulations benchmarked the isoAdvection-based solver against the standard OpenFOAM interIsoFoam solver and a multidimensional universal limiter for explicit solution (MULES)-based solver. Key performance parameters, including spray cone angle, liquid film thickness, and breakup length, were accurately captured, with maximum errors of 3.98% (isoAdvection) and 3.40% (interIsoFoam), outperforming MULES (7.79%). Overall, the developed solver demonstrates robust, quantitative agreement with experiments, accurately capturing nanoparticle transport, sedimentation dynamics, and primary atomization features in free-surface nanofluid flows under atmospheric and isothermal conditions.

Abstract Forced closure is widely used in conventional oil and gas reservoirs to promote uniform proppant placement. However, due to the extremely low permeability of shale formations, fracture closure requires more time, and the application of forced closure in shale formations has not been fully explored. In this study, we use a fully implicit 3D geomechanical fracture simulator to track the migration paths and settling patterns of proppants during hydraulic fracturing, investigating the impact of forced closure on proppant distribution in shale formations. The results show that forced closure, implemented immediately after injection, can significantly reduce proppant settling and increase the effective propped surface area from 29.74% to 38.68%, with a significant improvement. Furthermore, this study systematically analyzes the impact of various geological conditions and operational parameters on the effectiveness of forced closure, revealing that factors such as fracture height, fracturing fluid viscosity, formation permeability, and proppant concentration significantly influence the outcomes. This study provides critical theoretical foundations and practical guidance for optimizing hydraulic fracturing design, improving proppant distribution, and enhancing operational efficiency in shale formations.

Addressing the challenge of grasping position, which impacts the stability of dexterous hands, this study analyzes motion characteristics of underdriven dexterous hands and proposes a method to enhance grasping stability. Utilizing the improved Denavit–Hartenberg method and closed-loop vector method, kinematic models for multifingered dexterous hands — encompassing individual fingers, entire hands, and robot kinematics — were developed. The models facilitated simulation and analysis of each component’s operational space, offering a clear depiction of the hand’s grasping capabilities and providing foundational data for determining the appropriate size of objects to be grasped. Employing the constraints of finger-object contact and the principles of polygonal part grasping, a multifingered dexterous hand grasping model was constructed. An analysis of the initial contact force helix led to the exploration of a fundamental evaluation index for grasping quality based on force closure. Subsequently, an assessment of the grasping performance index was conducted under the condition of force closure. The optimization of the multifingered dexterous hand’s grasping position was achieved through the application of the maximum inscribed ball criterion, which identified the position with optimal stability. Experimental findings demonstrate that the proposed method significantly increases the resistance threshold by 1.71 times, thereby advancing the study of grasping stability for underactuated dexterous hands.

The manufacturing industry is currently facing major challenges. Environmental protection requirements, component complexity and material costs are continually growing. Lightweight design offers a solution, particularly in hybrid components, reducing weight while maintaining strength. Joining by forming processes based on plastic deformation offer high material efficiency and a reduced number of required parts. However, industrially established processes oppose a lack in flexibility for varying material thickness and strength class. Current research focuses on innovative and versatile mechanical joining processes. In this context, the process of orbital forming was investigated to be used as mechanical joining operation for dissimilar materials. The rotational movement of the tool enables a radial material flow, ensuring permanent form and force closure. To establish a reliable joint, a fundamental understanding of the process in terms of the material behavior is necessary. Therefore, the main focus of this investigation is introducing a novel numerical and experimental approach to identify the material flow during forming. A numerical model is utilized to simulate an orbital forming process and analyze the stress conditions as well as the resulting material flow. The joining partners include the dual-phase steel DP600 and the aluminum alloy EN AW-5754 with a thickness of 3.0 mm. The numerical simulation indicates that with increasing forming force, the material flow increases due to elevated compressive stresses. This assumption is confirmed by experimental investigations using various forces. In addition, the geometrical and mechanical properties of the joint were measured in further investigations, in order to validate the numerical process model.

Basal cell carcinoma (BCC) is the most common malignant tumor of the eyelid. These cancers often necessitate eyelid reconstruction in ophthalmic plastic surgery, which poses significant challenges. This study describes the use of a tarsoconjunctival flap from the orbicularis oculi muscle of the upper eyelid for reconstructing full-thickness lower eyelid defects following BCC resection. Four consecutive patients with full-thickness lower eyelid BCC underwent radical resection with 3-mm margins, followed by reconstruction using a tarsoconjunctival flap from the upper eyelid. Digital photographs were taken at baseline and at 1, 3, and 6 months postsurgery to evaluate clinical outcomes. Histological examination confirmed complete tumor excision in all cases. The modified Hughes procedure resulted in a high rate of functional and aesthetic success, with no recurrences observed over an average follow-up of 12 months. None of the patients experienced temporary forced eyelid closure, and both aesthetic and functional results were satisfactory. The tarsoconjunctival flap from the upper eyelid is an effective method for reconstructing extensive full-thickness lower eyelid defects, providing excellent functional and aesthetic outcomes.

The low stiffness of robots significantly limits their applicability within the aerospace assembly and manufacturing sectors. The majority of existing research focuses on optimizing robot posture; however, the efficacy of these approaches is constrained in situations with minimal posture variation. To address this challenge, this study examines a robotic drilling system designed for use in confined spaces. An in-depth analysis of its stiffness model is conducted, and the system’s stiffness limitations are identified using the stiffness ellipsoid evaluation method. Based on the mechanical analysis of the drilling state, a stiffness enhancement method grounded in the local force closure of the end effector is proposed. This method involves locking the end effector’s expansion module with the substrate during the drilling process, thereby enabling the axial drilling forces to be jointly borne by the expansion module and the robot’s base joints. Consequently, the system’s stiffness, particularly in the axial direction, is substantially improved. A series of experiments rigorously validate the effectiveness of the proposed stiffness enhancement method. The experimental results demonstrate that the stiffness-optimized robot reduces axial deformation during drilling by a factor of ten and significantly improves hole quality and exit burr height.

Abstract Research on robotic grasping and hand design has focused mainly on grasping one object at time, but many applications require to manipulate multiple objects at time. This review describes fundamental aspects of robotic hands design and grasping task implementation, and it is focused on grasping of multiple objects and some of their mathematical models. These topics can be clustered in a concept named Robotic Hand Grasping (RHG). Firstly, a general description of RHG is presented. Secondly, the state of the art of RHG applied to multiple objects is described. Finally, some important mathematical models, which include contact models, are presented. It is important to mention the relevance of hand pushing and the application of Active Force Closure when the grasping is applied to multiple objects.

This paper examines the impact of a rotationally superimposed punch stroke on the binding mechanisms of clinched joints of aluminum sheets. As part of the development of a method for ensuring the versatility of clinching, an additional rotational movement of the punch was introduced as a control variable to influence friction in the mechanical joining process. The effect of rotational superimposition on the force-displacement curve of the clinching processes was investigated using four test variants with different kinematics. The primary objective was to evaluate the binding mechanisms that maintain the integrity of the clinched joint. To evaluate the force closure of the resulting joint, two testing methods were employed throughout the course of the research, non-destructive resistance measurement using four-wire sensing method and destructive torsion testing. A crucial factor influencing the efficacy of the process is surface cleanliness, as contaminants between joining partners can impede the effectiveness of the clinched joint. Therefore, all specimens were meticulously cleaned prior to experimentation. This method exhibits promising potential in creating clinched joints that align with the demands of flexible manufacturing environments.

ABSTRACT Purpose To observe the morphological and functional changes associated with crowding by longitudinally following the same individuals during their mixed dentition period. Methods Subjects were 66 individuals with longitudinal data of mixed dentition, obtained every other year from 2012 to 2019. At T1 (when incisors and first molars had erupted and deciduous canines remained) and T2 (when permanent canines had fully erupted), Measurements were taken to observe and analyse trends in morphological and functional changes over time, without interventions. Morphometric measurements included three-dimensional evaluation of palatal, dentition and first molar tooth movement, and oral function measurements included width of the masticatory path, occlusal force and lip closure force. Results From T1 to T2, the palatal width diameter (PW), palatal depth (PD), dental arch width diameter (3AW, 6AW), and maxillary first molar buccolingual inclination (BLI) increased significantly, whereas the dental arch length diameter (AL’, AL) and the rotation angle of the maxillary first molars (RA) decreased significantly. Spearman’s rank correlation coefficients showed that 3AW and RA were significantly associated with the masticatory path width and occlusal force. Conclusions This study suggests that oral function during growth may be associated with changes in morphological characteristics that influence crowding.

Abstract At the time it closed in 1947, Middlesex University School of Medicine (MUSOM) in Waltham, Massachusetts was one of the few American medical schools that did not restrict the enrollment of Jews, who reportedly comprised 85 percent of its students. This school also welcomed students and faculty forced to flee Nazi-occupied Europe, and at least twenty-one faculty and eleven student refugees were offered sanctuary there during the Nazi period. Though Middlesex was an oasis from antisemitism, prevalent anti-Jewish attitudes and practices of its time may have caused its demise. After its forced closure, the school’s property was donated to the founders of a new Jewish-led university.

A semi-analytical transient undisturbed velocity correction scheme for wall-bounded two-way coupled Euler-Lagrange simulations

Abstract This paper investigates the factors determining the forced closures of firms, which occur when entrepreneurs fail to submit annual reports for their businesses. Drawing on various theoretical perspectives, including a novel focus on the past reporting misconducts of the same entrepreneurs, the study sheds light on this phenomenon. Analysis of Estonian micro‐firms run by serial entrepreneurs reveals that recent reporting misconducts, particularly those of a severe nature, significantly determine a firm's forced closure. Additionally, factors such as firm size, age, and certain aspects of corporate governance play significant roles in this regard. In turn, the financial performance of a firm largely fails to signal future forced closure, potentially indicating that when entrepreneurs submit annual reports showing normal performance, they might be hiding bad performance. The paper also delineates different types of violators based on the severity of their past misconducts, noting that a particular type characterized by a large number of severe violations is especially prone to forced closures. Finally, the paper develops high‐accuracy prediction models for forced closures, identifying the number of most severe violations and firm size as the most important variables.

Hemodialysis patients usually receive an arteriovenous fistula (AVF) in the arm as vascular access conduit to allow dialysis 2-3 times a week. This AVF introduces the high flow necessary for dialysis, but over time the ever-present supraphysiological flow is the leading cause of complications. This study aims to develop an implantable device able to non-invasively remove the high flow outside dialysis sessions. The developed prototype features a magnetic ring allowing external coupling and torque transmission to non-invasively control an AVF valve. Mock-up devices were implanted into arm and sheep cadavers to test sizes and locations. The transmission torque, output force, and valve closure are measured for different representative skin thicknesses. The prototype was placed successfully into arm and sheep cadavers. In the prototype, a maximum output force of 78.9 ± 4.2 N, 46.7 ± 1.9 N, 25.6 ± 0.7 N, 13.5 ± 0.6 N and 6.3 ± 0.4 N could be achieved non-invasively through skin thicknesses of 1-5 mm respectively. The fistula was fully collapsible in every measurement through skin thickness up to the required 4 mm. The prototype satisfies the design requirements. It is fully implantable and allows closure and control of an AVF through non-invasive torque transmission. In vivo studies are pivotal in assessing functionality and understanding systemic effects. A method is introduced to transfer large amounts of energy to a medical implant for actuation of a mechanical valve trough a closed surface. This system allows non-invasive control of an AVF to reduce complications related to the permanent high flow in conventional AVFs.

The quality of apple picking affects the sales of apples, and the grasping force of the end effector of an apple picking robot is very important for apple picking. It is easy to cause apple damage due to excessive contact force, or when the contact force is too small to grasp the apple. However, the current research lacks an analysis of the minimum stable grasping force of apples. Therefore, in order to realize the stable grasping of apples by the end-effector of a picking robot and reduce fruit damage, this study first analyzes the grasping stability of the end-effector based on the force closure theory, and comprehensively considers the force closure constraints, nonlinear friction cone constraints and the introduction of torque constraints. Next, the constraint conditions are processed using an obstacle function, and a penalty factor is introduced to construct an optimization model of the contact force distribution of the end-effector. Then, the improved Newton method is used to grasp and solve the contact force distribution model. Under the premise of selecting the penalty factor, the optimal contact force of grasping an apple is determined using a method of numerical example simulation analysis, and the validity of the solution is verified. In order to verify the reliability of the contact force distribution optimization model, the practical significance of the method for apple grasping is verified in an actual grasping experiment. The actual experiment shows that the method can provide the minimum stable grasping force to the end-effector to achieve stable grasping.

A novel cable configuration method for fully-actuated parallel cable-driven systems: Application in a shoulder rehabilitation exoskeleton

ZusammenfassungTo increase the recycling rate of components used in electric vehicles, metal–polymer composites are to be separated. As a basis, samples of polymers are ground in a hammer mill to analyze the influence of various pretreatments. The resulting particle size distributions are related to the mechanical properties of the polymers. The results can be used for a comminution of a metal–polymer composite from an electric vehicle's battery housing and show that lower temperatures perform the best for individual materials and composites. The complexity of the components and the type of joining also influence the comminution success of composite components, as a separation of the materials is easier with low complexity and force closure.

Caves and lava tubes on the Moon and Mars are sites of geological and astrobiological interest but consist of terrain that is inaccessible with traditional robot locomotion. To support the exploration of these sites, we present ReachBot, a robot that uses extendable booms as appendages to manipulate itself with respect to irregular rock surfaces. The booms terminate in grippers equipped with microspines and provide ReachBot with a large workspace, allowing it to achieve force closure in enclosed spaces, such as the walls of a lava tube. To propel ReachBot, we present a contact-before-motion planner for nongaited legged locomotion that uses internal force control, similar to a multifingered hand, to keep its long, slender booms in tension. Motion planning also depends on finding and executing secure grips on rock features. We used a Monte Carlo simulation to inform gripper design and predict grasp strength and variability. In addition, we used a two-step perception system to identify possible grasp locations. To validate our approach and mechanisms under realistic conditions, we deployed a single ReachBot arm and gripper in a lava tube in the Mojave Desert. The field test confirmed that ReachBot will find many targets for secure grasps with the proposed kinematic design.

Robotic Hand Grasping is a challenging task that is studied by different researchers, with contributions made to topics such as grasping quality measuring, synthesis, and mathematical models. However, these works usually consider grasping of only one object at time, which is not applicable when the hand must carry multiple objects. Multiple objects grasping problem can be approached as a packing problem, which consists in filling a container with objects of a determined geometry, using the space available in the most efficient way. The aim of this work is to obtain a design methodology for a two-finger gripper that optimizes the grasping capacity of slender cylindrical multiple objects, applying packing problem concepts. This case is of practical importance in grapple claws used in forest harvesting for picking logs. A mathematical model is presented that allows to obtain an optimized geometric configuration of the grapple claw for maximum grasping capacity and packing density for given numbers and sizes of logs. This model is analytically solved for the maximum radius of a set of logs that can be grasped. Alternatively, for a number of logs with a given diameter, the geometric dimensions of an optimized grapple claw can be obtained. The solutions are evaluated using packing density and Active Force Closure (AFC) as quality metrics, to show the benefits of adding them as design criteria in the design multiple objects grapple claws.

This article examines the use of euphemisms in German journalistic texts on economic topics. Euphemisms include lexemes and expressions that soften the names of discordant designations of concepts. The consequences of the 2019-2020 pandemic and the Ukrainian conflict had a definite impact on the German economy and the standard of living of the German population. The rapid rise in prices and the energy crisis that has arisen in the country have led to financial problems reflected in the stratification of society into rich and poor, an increase in the number of protests due to unfavorable working conditions and even to forced closure of enterprises. Such economic difficulties are actively discussed in the German press. In order to switch the reader’s attention and smooth out the designation of acute problems, journalists use euphemized words and expressions in their articles. In a particular historical period, depending on political, economic or social changes, certain spheres of public life were subjected to productive euphemization. In this regard, it seems important to trace this process in diachrony, focusing on the economic problems of Germany in 2021-2023. The aim of the study is to identify euphemistically colored lexemes and expressions in German journalistic texts, as well as to identify groups of euphemisms and the reasons for their use. The research material included articles from the economic section of German electronic publications such as “Der Spiegel”, “Die Zeit”, “Süddeutsche Zeitung”, “Die Tageszeitung”, “Berliner Zeitung”, etc. The study revealed that such economic problems as poverty and wealth, mass protests, rising food and electricity prices, methods of limiting them, and the consequences of the energy crisis are being euphemized. The analysis made it possible to identify both conventional and occasional euphemisms, although it was found that the lexemes and expressions of the second group are noticeably prevalent in German journalism.