Support Points Research Articles

Design of a Bionic Spider Robot with a Two-Degrees-of-Freedom Leg Structure and Body Frame

Spiders have unique biological characteristics and excellent maneuverability, making them an ideal model for bionic robot design. However, traditional bionic spider robot designs usually have multiple degrees of freedom and confront many challenges. These challenges include complex control requirements, higher energy consumption, larger size and weight, higher risk of failure, and higher cost. This study proposes a leg design with two degrees of freedom to reduce its control and manufacturing costs. It can better control leg movement and improve leg force through a multi-link mechanism and a dual-motor system. In addition, the triangular gait and hexagonal body structure align the weight of the body with the support point, thereby enhancing stability. This study offers a comprehensive and organized approach to bio-inspired robot design, providing a valuable reference for future bionic robot development.

Spectral element method for random vibration analysis of the vehicle-track coupling system

In this paper, we propose a new random vibration analysis model for the vertical vehicle-track coupling system, which combines the symplectic method and the spectral element method (SEM) to enhance calculation efficiency and accuracy. The model assumed that the vehicle is composed of a multi-rigid body with 10 DOFs, and its motion equation is derived using the traditional frequency analysis method. Tracks are considered periodic structures, and the part between sleeper support points is considered a substructure. The motion equation of the periodic track-substructure is established by spectral element method (SEM), and the propagation of vibration wave between the substructures is calculated by the symplectic method. The frequency responses of the vehicle-track coupling system are calculated by using the German low-interference irregularity spectrum and short-wave irregularity spectrum as excitation. Then, the rationality of this method is verified by comparing it with the results from the traditional symplectic method and simulations using Universal Mechanism software. The comparison shows that this method surpasses the traditional symplectic method in high-frequency accuracy while maintaining high computational efficiency. Although the finite element method also has the capability for high-frequency analysis, this method can calculate the high-frequency vibration of an infinitely long track using just one element, making it more suitable for the efficient analysis of vehicle-track coupling systems. Finally, the model is applied to analyze the distribution characteristics of the vibration response of the coupled system in the frequency domain.

Threats to the security of banking activities in modern Russian practice

Among other sectors of the Russian economy, the banking sector is one of the most dynamically developing. Consequently, its resistance to various shocks and possible threats will be one of the central points of support for the economic security of the state. Modern statistics show an increase in various types of incidents in the financial sector. Regular monitoring and detailed analysis of fraudulent schemes will minimize the possibility of criminal manipulation, thereby significantly reducing the number of risks and the amount of financial losses.The presented article provides a structural and geographical analysis of incidents in the financial sector recorded in 2023, and a sketch of the modern landscape of possible threats is compiled. The optimal approach to the formation of information and economic security of personal and financial data, in particular, and banking activities in general, involves comprehensive protection measures both from the point of view of the individual user and from the position of representatives of the banking community and the regulator.

Seismic resistance analysis and optimization of gymnasium truss structure

The gymnasium is mainly composed of truss structure, with a large span, and requires high seismic performance. To ensure greater stability of the truss structure, modal analysis was conducted on the mechanical model, yielding the natural frequencies and modal shapes. In order to improve the seismic performance, BRB rods were added to the support points, and the frame structure was reinforced with diagonal braces. Through modal verification, it can be seen that the stiffness of the truss structure was significantly improved. The internal forces of the truss were simulated under the El Centro and Taft seismic wave conditions. The results show that the optimized structure can significantly reduce the internal forces and improve the overall seismic performance. The fundamental natural period of the reinforced structure is less than that of the unreinforced structure, and the stiffness of the reinforced steel structure increases, making it more sensitive to vertical seismic motion.

Maintenance and Supply of Post and Telegraph Stations in the Semirechye

The article explores the material supply of post and telegraph stations in the Semirechye region during the late 19th and early 20th centuries. The management of postal routes, transport safety, and the construction and equipment of stations were determined by the state, private entrepreneurs, and the local Kazakh population, who were taxed for these services. In addressing these challenges, the Russian Empire drew from European experiences, directly applying the postal station management model from Russia. Postal routes facilitated the transportation of correspondence, cargo, and passengers, thus solving essential communication issues within society. Government officials and soldiers also relied on these stations as key support points. Although the station attendants (overseers) were under the authority of post offices, they independently managed operations and relied on station-generated income. This arrangement was cost-effective for the state, allowing it to minimize expenses on postal institutions. The Russian government consistently worked to improve postal communication, and the system was subject to ongoing changes. However, despite some positive developments, both the Russian Empire and the postal system in Semirechye lagged behind European standards of postal transport.

Multi-body mesh deformation using a multi-level localized dual-restricted radial basis function interpolation

Multi-body dynamic problems with moving boundaries are prevalent in the computational fluid dynamics. In these problems, the original mesh is unsuitable for subsequent solution steps and is needed to be deformed. The radial basis function (RBF) interpolation is a common algorithm for the mesh deformation task. However, the multi-body mesh may contain numerous individuals and volume nodes, which will harm the computational efficiency. In order to optimize this process, we propose a new method for the mesh deformation of the multi-body configuration. In this new approach, each individual is deformed separately. Thus the global problem is decomposed into a series of local mesh deformation problems. As the computational cost to construct the interpolation system in RBF algorithm is proportional to the cube of the number of support points on the surface, converting it into multiple local mesh deformation problems can effectively reduce the CPU cost. To treat each local problem, we employ a dual-restricted RBF interpolation technique which could avoid the influence of moving individual on the other individuals. This new localized approach effectively improves the computational efficiency to construct the interpolation system but sometimes will increase the CPU cost of the mesh updating procedure. To avoid this drawback, the existed multi-level restricted RBF strategy is coupled with the new localized method to further reduce the CPU cost to update the mesh. The combination of the two techniques could enhance their advantages and avoid their drawbacks. Some numerical examples have demonstrated the abilities of the new algorithm. For instance, in the case of the three-dimensional birds flock, the CPU time to construct the interpolation system and deform the volume mesh was respectively reduced by three and two orders of magnitude compared to the global single-level method.

On the Conflation of Negative Binomial and Logarithmic Distributions

In recent decades, the study of discrete distributions has received increasing attention in the field of statistics, mainly because discrete distributions can model a wide range of count data. One common distribution used for modeling count data, for instance, is the negative binomial distribution (NBD), which performs well with over-dispersed data. In this paper, a new count distribution is introduced, called the conflation of negative binomial and logarithmic distributions, which is formed by conflating the negative binomial and logarithmic distributions, resulting in a distribution that possesses some of the properties of negative binomial and logarithmic distributions. The distribution has two parameters and is verified by a positive integer. Two modifications are proposed to the distribution, which includes zero as a support point. The new distribution is valuable from a theoretical perspective since it is a member of the weighted negative binomial distribution family. In addition, the distribution differs from the NBD in the sense that the probability of lower counts is inflated. This study discusses the characteristics of the proposed distribution and its modified versions, such as moments, probability generating functions, likelihood stochastic ordering, log-concavity, and unimodality properties. Real-world data are used to evaluate the performance of the proposed models against other models. All computations shown in this paper were produced using the R programming language.

Quantified active learning Kriging model for structural reliability analysis

A quantified active learning Kriging-based (qAK) methodology for structural reliability analysis is presented. The proposed approach is based on an updated probability density function (PDF), which is dominant in the vicinity of the limit-state surface. This PDF is created using weights based on an improved learning function called the most probable misclassification function. This function is used as a metric for efficiently updating the Kriging model, as it symmetrically quantifies the uncertainty of candidate points in terms of the model’s accuracy. The proposed approach accurately approximates the points that lie on the limit-state surface. Moreover, a probabilistic-based stopping criterion is proposed. The new support points are selected using the weighted K-means algorithm and the sample from the updated PDF. Thus, the method does not require solving an optimization problem or using a sampling algorithm. The proposed qAK methods are more reliable and robust than previous implementations of the Kriging method for structural reliability assessment. The proposed approach is presented within the framework of standard reliability methods, i.e., the Monte Carlo and the Subset Simulation methods. The efficiency of the proposed qAK methods is demonstrated with the aid of six case studies.

A new mesh deformation method using quaternion and displacement normal propagation for high quality and high efficiency

Mesh deformation technology is widely used in aerodynamic applications like unsteady flow, aeroelasticity, and aerodynamic shape optimization because of its low computational costs and consistent mesh connectivity. In order to raise deformed mesh quality and improve efficiency, a new mesh deformation method based on quaternion and displacement normal propagation (named QN method) is introduced in this paper. The boundary points propagate their displacements composed of translational vectors and quaternions to corresponding volume points along the normal direction under the control of the damping function, which preserves the mesh shape and guarantees the quality near boundaries, including orthogonality and normal size. It can also prevent the volume points from being interfered by other less relevant boundary points, so dealing with complex displacement fields effectively. In addition, it avoids complicated matrix and interpolation operations, thus saving lots of computational costs. For mesh with complex topology, a hybrid method combining the QN method and the radial basis function method (RBF method) is investigated to broaden application scenarios, which are applied to the mesh with normal correspondence inside the boundary layer and the mesh outside, respectively. Benefitting from effective handling for the near-wall elements by the QN method, the RBF interpolation part in the hybrid method requires minor support points to carry out valid large deformation, improving the deformation efficiency greatly compared to the individual RBF method. Five typical test cases with different deformation modes and mesh characteristics are implemented, showing better performance of the proposed method in deformed mesh quality and deformation efficiency.

ECONOMIC EFFICIENCY OF APPLICATION OF OPTIMIZED MILL BED

This paper presents the selection of optimization parameters for the bed geometry of a long metal cutting machine (MCM), the design problem and boundary conditions were given. Five different geometries were designed for further mathematical analysis to meet the requirements of the problem. Static analysis of the mathematical model of the bed shells was performed by finite element method (FEM) using BETA CAE System tool, ABAQUS, which showed that by using stiffeners in the form of two variable pitch spirals and three hollow tubes, as well as changing the design at the connection point of the beam support to the bollards of the long bed of the metal cutting machine, the stresses that occurred in these places at an angle of 90° were reduced. The geometries were chosen in such a way that it was possible to reduce the stresses occurring at the point of cutting, to reduce the deflection, to increase the rigidity of the structure. The economic calculation aimed at determining the cost of a long metal-cutting machine tool with the proposed geometry has been carried out. The analysis of the unit cost of the product (long bed of the metal-cutting machine tool made of polymer concrete with optimized geometry) has been carried out, the calculation of the annual economic effect from the use of the proposed method of manufacturing has been carried out. Keywords: MCM, FEM, statistical analysis, product cost, economic calculation.

Ti6Al4V alloy with diamond particle-reinforced Cu-based coatings: Microstructure and tribological performance

To enhance the surface wear resistance of the Ti6Al4V alloy, diamond particles-reinforced Cu-based composite coatings (D500/D1000/D2000 coating: 500/1000/2000 mesh diamond: Cu-based alloy powder = 1:30 (wt%)) were fabricated by vacuum cladding. Cu-based alloys with liquid phase temperatures lower than the phase transition temperature of Ti6Al4V alloys were employed as cladding materials to avoid performance deterioration of Ti6Al4V substrates. The microstructure, mechanical properties, and dry-sliding tribological properties of the Cu-based composite coatings have been investigated systematically. The Cu-based composite coatings are composed of the ductile intermetallic compounds Ti3Sn and SnTi2 as the metal matrix, the hard and brittle intermetallic compounds CuTi, CuTi2, Ti(Cu, Al)2 and CuSn3Ti5, in situ generated TiC and the directly introduced diamond particle as the reinforced phases. In addition, a TiC hard phase protective layer was formed around the diamond particles, which retained the original properties of the diamond. The hardness of diamond particles-reinforced Cu-based composite coatings is much higher than that of the Ti6Al4V. Among them, the D2000 coating possesses the highest microhardness. The average Vickers hardness (HV0.5) on the coating surface and nanoindentation hardness (H) on the coating cross-section (the middle part without diamond particles) of the D2000 coating are 1329.8 HV0.5 and 16.87 GPa), which are 4–5 times higher than that of the Ti6Al4V substrate (333 HV0.5 and 3.37 GPa). Nevertheless, the D2000 coating (wear rate of 50.75 ×10−5 mm3/Nm) demonstrates slightly inferior tribological performance compared to the D500 coating. The wear rate of the latter is approximately 13.37 × 10−5 mm3/Nm, which is only 1/5.6 of the substrate (75.67 ×10−5 mm3/Nm). The larger the diamond particle size, the more the diamond serves as a bearing capacity support point to prevent the hard WC ball from further ploughing into the composite coating, and the better the wear resistance of the coating. Notably, D500 coating with excellent wear resistance has the potential for application in various fields of the machinery industry, marine engineering, and aerospace.

Numerical calibration for fracture parameters of three-point bending semi-circular specimens

This study aims to refine the fracture characterization of three-point bending semi-circular specimens used in rock fracture toughness assessments. The primary objective is to improve the accuracy of such evaluations by developing numerical simulations of specimens with pre-engineered cracks of varying geometries. Numerical simulations were conducted using the finite element method. The interaction integral method was employed to quantify the stress intensity factors (SIFs) and T-stress at crack tips. Initially, the model’s accuracy was validated by replicating stress singularities at crack tips in a benchmark circular disk with a central straight crack. Following validation, dimensionless fracture parameters specific to the three-point bending semi-circular specimens were calibrated. The numerical results demonstrate that the dimensionless stress intensity factor (YI) increases with both the relative crack length (a/R) and the spacing between support points. Notably, for relative crack lengths a/R ≤ 0.5, the dimensionless T-stress assumes negative values, initially decreasing and then increasing as the relative crack length increases. The findings of this study provide valuable insights into the fracture behavior of three-point bending semi-circular specimens with pre-engineered cracks. Based on the observed trends in the dimensionless fracture parameters, it is recommended that relative crack lengths within the range of 0.2–0.6 be used to maintain the accuracy of rock fracture toughness tests. The finite element method used in this study serves as a robust tool for calibrating fracture parameters, thereby laying a strong foundation for the application of these specimens in rock fracture toughness evaluations.

Large-Scale Low-Rank Gaussian Process Prediction with Support Points

Low-rank approximation is a popular strategy to tackle the “big n problem” associated with large-scale Gaussian process regressions. Basis functions for developing low-rank structures are crucial and should be carefully specified. Predictive processes simplify the problem by inducing basis functions with a covariance function and a set of knots. The existing literature suggests certain practical implementations of knot selection and covariance estimation; however, theoretical foundations explaining the influence of these two factors on predictive processes are lacking. In this paper, the asymptotic prediction performance of the predictive process and Gaussian process predictions are derived and the impacts of the selected knots and estimated covariance are studied. The use of support points as knots, which best represent data locations, is advocated. Extensive simulation studies demonstrate the superiority of support points and verify our theoretical results. Real data of precipitation and ozone are used as examples, and the efficiency of our method over other widely used low-rank approximation methods is verified.

Unveiling the Role of Emotion Regulation in the Relationship between Intimate Partner Violence Increases and Post-Traumatic Stress Disorder: A Mediation Analysis.

(1) Background: Experiencing intimate partner violence (IPV) can greatly impact victims' physical and mental health, often leading to post-traumatic stress disorder (PTSD). Emotion regulation has been identified in the literature as a factor that contributes to the manifestation of PTSD. Consequently, this study aims to investigate the relationship among the increase in IPV victimization (i.e., physical, psychological, sexual, and economic violence), emotion dysregulation, and PTSD symptoms. It has been hypothesized that emotion dysregulation may mediate the increase in IPV occurrence and PTSD symptoms. (2) Methods: 284 women (Mage = 40.92) exposed to IPV were recruited in Italy. IPV experience was screened using the Revised Conflict Tactic Scale questionnaire. A mediational analysis was performed using Rstudio. (3) Results: The findings corroborated the mediating role of emotion dysregulation: the relationship between the increase in IPV and PTSD symptoms appears to be mediated by emotion dysregulation. (4) Conclusions: These findings bolster the existing literature regarding the association between emotion dysregulation and PTSD, underscoring the important role of emotion dysregulation in trauma symptoms. This highlights the significance of prioritizing the treatment of emotion dysregulation as a focal point for intervention and support for those who have experienced IPV.

Dynamic balance of circles with one support point on pommel horse exercise

Double-leg circles on pommel horse exercises require a high degree of dynamic balance. However, theoretical conditions for maintaining dynamic balance are unclear. The purpose of this paper is to propose a simple theoretical model of the dynamic balance of the circles, and to illustrate its qualitative properties. To this end, the body of a gymnast is simply modeled as one rigid body with one support point, and symmetric and constant-velocity circles are assumed in most analyses. The condition that the torques of wrist and shoulder joints are zero is assumed as a dynamic balance condition with minimum strength. A control law is proposed to demonstrate the motion. Various properties of the dynamic balance condition are analyzed as follows. In the symmetric circles, (1) as the period of a circle decrease, the heights and the radius of the toes increase, and (2) the rotation of the body around its longitudinal axis in the double-leg circle has the effect of lifting the toes. (3) The shoulder and wrist torques can change the pose around the dynamic balance condition. In asymmetric circles, (4) the radius of the center of mass (CoM) increases as the angular velocity of the CoM around the support point decreases, and (5) the body angle with respect to the horizontal plane increases as the upward acceleration of the CoM increases. Moreover, mechanical principles of the circles are discussed as follows. (6) The CoM motion during the symmetric circles of the simple model can be related to the conical pendulum. In the simple model, (7) the pommel reaction force should be parallel to the arm segment when the wrist torque and the shoulder torque are equal or zero, and (8) to change the vertical component of the angular momentum of the body around the support point, the wrist torque around the vertical axis is needed. These results provide theoretical and qualitative insights into understanding and improving pommel horse exercise.

Empirical Monte Carlo evidence on estimation of timing-of-events models

This article builds on the Empirical Monte Carlo simulation approach to study the estimation of Timing-of-Events (ToE) models. We exploit rich Swedish data of unemployed job seekers with information on participation in a training program to simulate placebo treatment durations. We first use these simulations to examine which covariates are key confounders to be included in dynamic selection models for training participation. The joint inclusion of specific short-term employment history indicators (notably, the share of time spent in employment), together with baseline socio-economic characteristics, regional and inflow timing information, is important to deal with selection bias. Next, we omit subsets of explanatory variables and estimate ToE models with discrete distributions for the ensuing systematic unobserved heterogeneity. In many cases, the ToE approach provides accurate effect estimates, especially if time-varying variation in the unemployment rate of the local labor market is taken into account. However, assuming too many or too few support points for unobserved heterogeneity may lead to large biases. Information criteria, in particular those penalizing parameter abundance, are useful to select the number of support points. A comparison with other duration models shows that a Stratified Cox model performs well with abundant multiple spells but less well when multiple spells are uncommon. The standard Cox regression model performs poorly in all configurations as it is unable to account for unobserved heterogeneity.

A review of electrodynamic tether missions: Historical trend, dimensionless parameters, and opportunities opening space markets

More than half a century after pioneering theoretical works proposed them, about 27 missions with long orbiting conductors have been carried out on suborbital and orbital flights,. The analysis of this review work organized them based on type of tether (insulated or bare), type of cathode (hollow cathode, expellant-less cathode, and no cathode), and the cross-section of the tether. It shows that, while all the missions in the 20th century used insulated and round tethers, the bare tether concept clearly dominated in the 21st century. Due to the cancellation of the ProSEDS mission and the suborbital character of the T-REX experiment, no tether mission with a bare tether and a hollow cathode has been on-orbit demonstrated. The E.T.PACK mission, planned by 2025/2026, can be the first on-orbit experiment testing such special EDT system, which is the one offering the largest propulsive performance. Therefore it can represent a turning point for the limited support received for the technology in the 21st century, confirmed by the fact that the total tether length used in the missions reduced from more than 40 km to less than 4 km between the 20th and 21st centuries. The study finds and discusses some important dimension-less parameters related to electrodynamic performance, current collection, and dynamic characteristics of the ProSEDS PROX-1, TEPCE, and E.T.PACK missions. Finally, some ideas to promote the opening and support of markets in the space sector by using electrodynamic tethers are provided.

Towards Establishing Quality Standards on Human Rights for Services in Dementia Care.

People with dementia often experience violations of fundamental human rights and impeded access to healthcare. This study aims to investigate the views of experts regarding the use of the United Nations Convention on the Rights of People with Disabilities (CRPD) principles as quality standards for human rights-based care. A single-round Delphi e-consultation with 15 dementia experts was designed to evaluate each CRPD principle and collect feedback on their views about the application of the CRPD principles in dementia care. The CRPD principles were fully endorsed as quality standards; however, several experts commented on the complexities of the use of CRPD principles in relation to information disclosure, capacity assessment, stakeholders' involvement in decision-making, respecting needs and preferences, holistic approaches in care practice, and protection against abuse, neglect and discrimination. These findings indicate the CRPD quality standards were fully applicable for people with dementia although some clarification around interpretation could assist in their use. Future research should elaborate on further points of support and guidance for dementia care providing examples of good practice from across the globe, and develop a concordant, human rights-based scheme for the implementation and evaluation of dementia services. This study suggests that the CRPD can serve as a benchmark for human rights-based practices in dementia services globally that could enhance nursing care practice. Nursing staff are encouraged to consider human rights in relation to the complexities associated with people with dementia, their caregivers, and other services involved in their care.

Survivorship and Clinical Outcomes of Reverse Total Shoulder Arthroplasty in Patients with Large Glenoid Defects Using the Stilting Technique and a Baseplate with Central Ingrowth Cage and Peripheral Locking Screws

Stilting is a novel technique used in reverse shoulder arthroplasty (RSA) in patients with significant glenoid bone loss. This technique utilizes peripheral locking screws placed behind an unseated portion of the baseplate, to transmit forces from the baseplate to the cortical surface of the glenoid, without the need for bone grafting. The stilted screw, once locked, provides a fixed angle point of support for an unseated aspect of a baseplate. The primary advantages of this technique are reduced cost compared to a custom implant and reduced operative time compared to bone grafting. We conducted a retrospective, non-randomized, comparative cohort study of 41 patients underwent primary Reverse Shoulder Arthroplasty (RSA) using the Stilting Technique with the Exactech Equinoxe Reverse System (Gainesville, FL, USA) at a single, academic center from the years 2004-2021. Exclusion criteria included age under 18 or over 100, and oncologic or acute fracture RSA indications. Operative data was documented, including implant records, percent baseplate seating, and operative duration. Survivorship was compared among primary stilted-RSA (n=41), bone graft-RSA (n=42), and non-stilted/non-bone grafted RSA (n=1,032) within our institutional shoulder arthroplasty database. A radiographic examination of baseplate failure was also conducted across the study groups. Postoperative functional outcomes were compared in a matched analysis involving patients with a minimum 2-year follow-up between stilted patients and a non-stilted/non-bone grafted control group for primary RSA. All Stilted-RSA cases utilized metal augments and demonstrated a mean baseplate seating of 61% (range 45-75%). For stilted RSAs, survivorship was 100% and 92.6% at 2- and 5-years, compared to 98.3% and 94.6% for non-stilted/non-bone grafted and 96.3% and 79.5% for bone-grafted RSAs (p=0.042). At 5-years, the baseplate-related failure rates were greater in the stilted (7.4%) and the bone-grafted (9.3%) cohorts compared with the non-stilted/non-bone grafted cohort (1.1%, p<0.001). The mean time to baseplate failure was 30 months for stilted RSA. Functional outcomes for primary RSA were statistically similar between stilted and non-stilted patients, including range of motion, Constant, ASES, SST, UCLA, and SPADI scores. The stilted-RSA cohort exhibited noninferior revision and baseplate failure rates to that of bone-grafted RSA. This suggests that stilting may be a viable technique for patients undergoing primary RSA with significant glenoid deformity.

A Non‐Linear Model for Multiple Alcohol Intakes and Optimal Designs Strategies

ABSTRACTThis study addresses the complex dynamics of alcohol elimination in the human body, very important in forensic and healthcare areas. Existing models often oversimplify with the assumption of linear elimination kinetics, limiting practical application. This study presents a novel non‐linear model for estimating blood alcohol concentration after multiple intakes. Initially developed for two different alcohol incorporations, it can be straightforwardly extended to the case of more intakes. Emphasising the significance of accurate parameter estimation, the research underscores the importance of precise experimental design, utilising optimal experimental design (OED) methodologies. Sensitivity analysis of model coefficients and the determination of D‐optimal designs, considering correlation structures among observations, reveal a strong linear relationship between support points. This relationship can be used to obtain nearly optimal designs that are highly efficient and much easier to compute.