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Abstract: In concurrent work, we introduced a novel robotic package delivery system latching intelligent modular mobility system (LIMMS). Each LIMMS end effector requires a small, lightweight latching mechanism for pre-manufactured containers, such as cardboard boxes. In order to effectively process a high volume of packages, aligning the latching mechanism quickly and reliably is critical. Instead of depending on highly accurate controllers for alignment, we propose a novel self-aligning rotational mechanism to increase the system’s tolerance to misalignment. The radial latching design consists of evenly spaced blades that rotate into slots cut into the box. When misaligned, the blades contact the edges of the engagement slots, generating a self-correcting force that passively centers the blades with the slot pattern. This paper introduces a mathematical framework with closed form expressions to quantify error tolerance for these mechanisms. Through our mathematical and optimization analyses, it is shown that a two-blade design can tolerate a maximum misalignment of three times the radius to the blade tips, much larger than commonly used designs with three or more blade-like contacts. Our approach can be generalized for a class of rotational latching mechanisms with any number of blades. Utilizing this theory, a design process is laid out for developing an optimal self-aligning rotational latching mechanism given desired parameters and task constraints. With this methodology, we designed, manufactured, and verified the effectiveness of both two-blade and three-blade self-aligning in practical experiments.

Mobile bed to move patients in hospitals is a critical aspect in a healthcare system. Typical hospital beds often require significant manpower and impose physical stresses on caregivers. This paper explores potential solutions to improve hospital bed mobility, focusing on the integration of robotic technologies. Existing literatures on the subject are reviewed, including studies on hospital bed design structures, ergonomic considerations, and implementations of robotics. Different types of wheels suitable for robot movements are discussed, covering conventional wheels, omniwheels, mecanum wheels, swerve drives, and powered fifth wheels. Each wheel type is described and its advantages and disadvantages are highlighted. The comparison of these wheel types helps identify the most suitable option for modifying hospital beds while maintaining their maneuverability. Furthermore, the paper draws inspiration from many applications of mobile robots in other industries, such as automated guided vehicles (AGVs) and autonomous mobile robots (AMRs), to explore potential innovations for the healthcare. By leveraging robotic technologies, hospitals can enhance efficiency and alleviate the burden on healthcare workers. [ABSTRACT FROM AUTHOR]

The rail rolling stock undercarriage condition monitoring is proposed by using an automated measuring system, located on the railway track and measuring the specified parameters of the wheels directly, while the train is moving. Regular undercarriage condition monitoring reduces the costs of preventive maintenance of rolling stock without compromising the traffic safety. An algorithm has been developed for the operation of a special software package for visualizing and assessing monitoring data on the condition of the undercarriage of rail rolling stock. The software package consists of separate software modules that can be used independently of each other. It is possible to make short- or long-term predictions of the behavior of any of the monitored parameters using an proposed automated measuring system. [ABSTRACT FROM AUTHOR]

Abstract Mobile bed to move patients in hospitals is a critical aspect in a healthcare system. Typical hospital beds often require significant manpower and impose physical stresses on caregivers. This paper explores potential solutions to improve hospital bed mobility, focusing on the integration of robotic technologies. Existing literatures on the subject are reviewed, including studies on hospital bed design structures, ergonomic considerations, and implementations of robotics. Different types of wheels suitable for robot movements are discussed, covering conventional wheels, omniwheels, mecanum wheels, swerve drives, and powered fifth wheels. Each wheel type is described and its advantages and disadvantages are highlighted. The comparison of these wheel types helps identify the most suitable option for modifying hospital beds while maintaining their maneuverability. Furthermore, the paper draws inspiration from many applications of mobile robots in other industries, such as automated guided vehicles (AGVs) and autonomous mobile robots (AMRs), to explore potential innovations for the healthcare. By leveraging robotic technologies, hospitals can enhance efficiency and alleviate the burden on healthcare workers.

The current scallop fishery sector allows many scallops to remain in specified fishing zones, and this process leads to heavy losses in the sector. Scallop fishermen aim to harvest the remaining scallops to reduce their losses. To achieve this, a fisherman must understand the scallop ecology on the seafloor. In our previous study, we proposed a method for measuring scallops using wheeled robots. However, a wheeled robot must be able to resist disturbance from the sea to achieve high measurement accuracy. Strong anchoring of wheels against the seafloor is necessary to resist disturbance. To better understand anchoring performance, we confirmed the wheel anchoring capacity in water-containing sand in an experiment. In this experiment, we towed fixed wheels on water-containing sand and measured the resistance force acting between the wheel and the sand. Afterward, we considered the resistance force as the wheel anchoring capacity on the water-containing sand. The experimental results capture the tendency for the anchoring capacity of sand with/without water to increase with sinkage. The results also demonstrate that the anchoring capacity of water-containing sand is lower than that of non-water-containing sand. However, the results indicate that when the wheels possess lugs, their presence tends to increase the wheels' anchoring capacity in water. [ABSTRACT FROM AUTHOR]

T6 heat treatment is usually applied to Al-Si-Mg alloy parts. This process can be modeled and solved by computer simulations for reduced experimental costs and environmental effects, and more flexible design approaches because this approach can avoid a high number of experiments based on trial and error. In the first stage, microstructural and mechanical characterization studies were performed for three different conditions: as-cast, quenched and artificially aged. Also, according to the 3D scanner test results, dimensional change of three different regions was observed at all of the heat treatment steps. In the second part, the production steps of the aluminum alloy wheels were simulated for further evaluation of the heat treatment by analyzing yield strength, residual stress state and dimensional changes on the different regions of the alloy wheel's cross section. Yield strength predictions obtained by modeling based on quench factor analysis and Shercliff–Ashby can be considered compatible with the experimental yield strength values. Although the error percentage between predicted and measured values is less than %10 in outer and inner flange regions, a more significant error value is present for the spoke region. As quench factor analysis values increased, the measured hardness values also tended to increase. Compressive residual stress is mostly observed on the wheel surface after quenching, and a slight but insufficient stress relief was observed in the artificial aging step. The dimensional change obtained by simulation is highest in the outer flange region after quenching and dimensional change increased in all regions after the artificial aging. [ABSTRACT FROM AUTHOR]

The rail rolling stock undercarriage condition monitoring is proposed by using an automated measuring system, located on the railway track and measuring the specified parameters of the wheels directly, while the train is moving. Regular undercarriage condition monitoring reduces the costs of preventive maintenance of rolling stock without compromising the traffic safety. An algorithm has been developed for the operation of a special software package for visualizing and assessing monitoring data on the condition of the undercarriage of rail rolling stock. The software package consists of separate software modules that can be used independently of each other. It is possible to make short- or long-term predictions of the behavior of any of the monitored parameters using an proposed automated measuring system.

The current scallop fishery sector allows many scallops to remain in specified fishing zones, and this process leads to heavy losses in the sector. Scallop fishermen aim to harvest the remaining scallops to reduce their losses. To achieve this, a fisherman must understand the scallop ecology on the seafloor. In our previous study, we proposed a method for measuring scallops using wheeled robots. However, a wheeled robot must be able to resist disturbance from the sea to achieve high measurement accuracy. Strong anchoring of wheels against the seafloor is necessary to resist disturbance. To better understand anchoring performance, we confirmed the wheel anchoring capacity in water-containing sand in an experiment. In this experiment, we towed fixed wheels on water-containing sand and measured the resistance force acting between the wheel and the sand. Afterward, we considered the resistance force as the wheel anchoring capacity on the water-containing sand. The experimental results capture the tendency for the anchoring capacity of sand with/without water to increase with sinkage. The results also demonstrate that the anchoring capacity of water-containing sand is lower than that of non-water-containing sand. However, the results indicate that when the wheels possess lugs, their presence tends to increase the wheels’ anchoring capacity in water.

Many people assume that the orbits of the planets are far more elliptical than they actually are. However, the orbits of all the planets with the exception of Mercury and Mars are nearly perfect circles. If the orbits of the planets are modeled as 26 inch bicycle wheels, the deviation from a perfect circle is less than one millimeter. The Earth's orbit around the Sun is normally depicted as being highly elliptical in order to teach students about Kepler's laws. This has been identified as a possible source of the misconception that it is warmer in summer than winter because the Earth is closer to the Sun. A possible way forward is to first teach students that the orbit of the Earth is essentially circular, like a bicycle wheel, and that seasons are due to the tilt of the Earth's axis of rotation, and then switch to exaggerated elliptical orbits to teach Kepler's laws. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: In concurrent work, we introduced a novel robotic package delivery system LIMMS (Latching Intelligent Modular Mobility System). Each of LIMMS’ end effectors requires a small, lightweight latching mechanism for pre-manufactured containers such as cardboard boxes. In order to effectively process a high volume of packages, aligning the latching mechanism quickly and reliably becomes critical. Instead of depending on highly accurate controllers for alignment, we propose a novel self-aligning rotational mechanism to increase the system’s tolerance to misalignment. The latching design consists of evenly spaced blades that rotate into slots cut into the box. When misaligned, the blades contact the edges of the engagement slots, generating a self-correcting force that passively centers the blades with the slot pattern. This paper introduces a mathematical framework with closed form expressions to quantify error tolerance for for these mechanisms. Through our mathematical and optimization analyses, it is shown that a 2-blade design can tolerate a maximum misalignment: 5 ≈ 2.236 times the radius of the blade tips. Our approach can be generalized for a class of rotational latching mechanisms with any number of blades. Utilizing this theory, a design process is laid out for developing an optimal self-aligning rotational latching mechanism given desired parameters and task constraints. With this methodology, we designed, manufactured, and verified the effectiveness of both 2-blade and 3-blade self-aligning latches in practical experiments.

The condition of a railway vehicle's wheels is an essential factor for safe operation. However, the current inspection of railway vehicle wheels is limited to periodic major and minor maintenance, where physical anomalies such as vibrations and noise are visually checked by maintenance personnel and addressed after detection. As a result, there is a need for predictive technology concerning wheel conditions to prevent railway vehicle damage and potential accidents due to wheel defects. Insufficient predictive technology for railway vehicle's wheel conditions forms the background for this study. In this research, a real-time tire wear classification system for light-rail rubber tires was proposed to reduce operational costs, enhance safety, and prevent service delays. To perform real-time condition classification of rubber tires, operational data from railway vehicles, including temperature, pressure, and acceleration, were collected. These data were processed and analyzed to generate training data. A 1D–CNN model was employed to classify tire conditions, and it demonstrated exceptionally high performance with a 99.4% accuracy rate. [ABSTRACT FROM AUTHOR]

For graphs G and H, the Ramsey number r(G, H) is the smallest number N, such that any red/blue edge-coloring of K N contains either a red copy of G or a blue copy of H. Let F n = K 1 + n K 2 be a fan and W 4 = K 1 + C 4 be a wheel of order five. In this paper, we show that the Ramsey number r (W 4 , F n) = 4 n + 1 for all sufficiently large n. Moreover, this implies that a large fan F n is W 4 -good. [ABSTRACT FROM AUTHOR]

The article presents the results of experimental studies on a micro-hydro power plant (MHP) designed for low-pressure flows. Waveforms of changes in the shaft torque and rotation speed of the MHP water wheel are obtained. Based on the waveforms, curves of the considered parameters are constructed and analyzed. The energy conversion efficiency of the water wheel is determined. [ABSTRACT FROM AUTHOR]

Let G be a graph of order n and size m. A vertex magic total labeling of G is a one-to-one function f: V(G)UE(G)-{1,2,···,n+m} with the property that for each vertex u of G, the sum of the label of u and the labels of all edges incident to u is the same constant, referred to as the magic constant. Such a labeling is even if f [V(G)] = {2,4,6,···,2n}. A graph G is called an even vertex magic if there is an even vertex magic total labeling of G. The primary goal of this paper is to study wheel related graphs with the size greater than the order, which have an even vertex magic total labeling. For every integer n=3 and t=1, the t-fold wheel Wn,t is a wheel related graph derived from a wheel Wn by duplicating the t hubs, each adjacent to all rim vertices, and not adjacent to each other. The t-fold wheel Wn,t has a size nt+n that exceeds its order n+t. In this paper, we determine the magic constant of the t-fold wheel Wn,t, the bound of an integer t for the even vertex magic total labeling of the t-fold wheel Wn,t and the conditions for even vertex magic Wn,t, focusing on integers n and t are established. Additionally, we investigate the necessary conditions for the even vertex magic total labeling of the n-fold wheel Wn,n when n is odd and the n-fold wheel Wn,n-2 when n is even. Furthermore, our study explores the characterization of an even vertex magic Wn,t for integer 3=n=9. [ABSTRACT FROM AUTHOR]

The interest in airless or non-pneumatic tire (NPT) structures emerges due to potential performance and environmental advantages, such as reduced rolling resistance and improved recyclability, when compared with traditional rubber-based pneumatic tires. NPTs can already be found in commercial applications such as forklifts, electric scooters, and wheelchairs. Even so, up to the knowledge of authors, there is no known established large-scale production of NPTs for most applications. This work presents a systematic literature review regarding the mechanical design and development of NPTs. A summary of structural characteristics and mechanical behaviour analysis is provided. Relevant standards, analysis strategies, materials, production techniques, and the end-of-life of tires are addressed. In the end, the authors debate the current challenges and prospects of these emergent products. Furthermore, this research aims at being used as a tool, potentiating the development of innovative and efficient, airless tire solutions. The review presented clarifies that many academic efforts are focused on finding optimal functional designs, which are frequently complex and physically demanding. These geometrically complex design proposals are, in most cases, composed of intricate cellular structures and spokes arrangements. Based on the current lack of knowledge, authors identify key research areas to be further developed such as the production, performance, and reliability of NPTs. It is debatable whether there will ever be a shortcoming of the rubber tire, or a time when fully recyclable tires are a societal obligation. Nevertheless, the number of reasons to promote the development of a reliable replacement to the traditional tire is far from scarce. [ABSTRACT FROM AUTHOR]

The wheels of railway vehicles are of paramount importance in relation to railroad operations and safety. Currently, the management of railway vehicle wheels is restricted to post-event inspections of the wheels whenever physical phenomena, such as abnormal vibrations and noise, occur during the operation of railway vehicles. To address this issue, this paper proposes a method for predicting abnormalities in railway wheels in advance and enhancing the learning and prediction performance of machine learning algorithms. Data were collected during the operation of Line 4 of the Busan Metro in South Korea by directly attaching sensors to the railway vehicles. Through the analysis of key factors in the collected data, factors that can be used for tire condition classification were derived. Additionally, through data distribution analysis and correlation analysis, factors for classifying tire conditions were identified. As a result, it was determined that the z-axis of acceleration has a significant impact, and machine learning techniques such as SVM (Linear Kernel, RBF Kernel) and Random Forest were utilized based on acceleration data to classify tire conditions into in-service and defective states. The SVM (Linear Kernel) yielded the highest recognition rate at 98.70%. [ABSTRACT FROM AUTHOR]

• Design and construction of single wheel test rig for Ocean World rover is presented. • Built using commercially available mechanical parts, motors, actuators, and sensors. • Test rig allows control of slip ratio, vertical load, slip angle, and camber angle. • Modular test-bed can simulate fine-grained ice, sharp ice, and ice boulder fields. Ocean Worlds such as Europa and Enceladus are known to harbor subsurface liquid water oceans under their icy crust and are high-priority targets for in situ exploration. Compared to the Moon and Mars, Ocean Worlds likely present a significantly more challenging environment for surface mobility systems due to the extremely cold temperature, high radiation dosage, and poorly constrained material properties under these conditions. Small-diameter wheels such as those used by Mars rovers are prone to slip-sinkage in loose soil and damage from sharp rock and ice formations. A 4-wheel rover with a simple drive system and large deployable compliant tires is proposed as a solution for extreme terrain mobility on Ocean World surfaces. The present work describes the design and construction of a single wheel test rig and a prototype large-diameter deployable wheel for Ocean World rovers and initial test results. The test rig allows independent control of the vertical load, slip ratio, slip angle, and camber angle, and accommodates large-diameter deployable wheels. The test rig features a modular test bed that can simulate varied surface features such as fine-grained ice, smooth hard ice, sharp ice formations, and large ice boulder fields. [ABSTRACT FROM AUTHOR]

The optimal hardness range of the hardened wheel rim and the rolling surface of the rail is determined, in terms of maximum wear resistance of the wheel–rail pair. Laboratory tests in operational conditions establish the optimal hardness ratio of the wheel and rail. [ABSTRACT FROM AUTHOR]

Let $ G $ be a graph of order $ n $ and size $ m $. A vertex magic total labeling of $ G $ is a one-to-one function $ f $: $ V(G) \cup E(G) \rightarrow \{1, 2, \cdots, n+m\} $ with the property that for each vertex $ u $ of $ G $, the sum of the label of $ u $ and the labels of all edges incident to $ u $ is the same constant, referred to as the magic constant. Such a labeling is even if $ f[V(G)] = \{2, 4, 6, \cdots, 2n\} $. A graph $ G $ is called an even vertex magic if there is an even vertex magic total labeling of $ G $. The primary goal of this paper is to study wheel related graphs with the size greater than the order, which have an even vertex magic total labeling. For every integer $ n \geq 3 $ and $ t \geq 1 $, the $ t $-fold wheel $ W_{n, t} $ is a wheel related graph derived from a wheel $ W_n $ by duplicating the $ t $ hubs, each adjacent to all rim vertices, and not adjacent to each other. The $ t $-fold wheel $ W_{n, t} $ has a size $ nt + n $ that exceeds its order $ n + t $. In this paper, we determine the magic constant of the $ t $-fold wheel $ W_{n, t} $, the bound of an integer $ t $ for the even vertex magic total labeling of the $ t $-fold wheel $ W_{n, t} $ and the conditions for even vertex magic $ W_{n, t} $, focusing on integers $ n $ and $ t $ are established. Additionally, we investigate the necessary conditions for the even vertex magic total labeling of the $ n $-fold wheel $ W_{n, n} $ when $ n $ is odd and the $ n $-fold wheel $ W_{n, n-2} $ when $ n $ is even. Furthermore, our study explores the characterization of an even vertex magic $ W_{n, t} $ for integer $ 3 \leq n \leq 9 $.

Different variants of the hardness of the wheel/rail friction pair were investigated to determine the optimal hardness range of the wheel/rail that ensures the minimum wear under selected test conditions. A pair of tests was performed on an MI-2 machine with a cylindrical wheel steel roller and a rail steel liner. The hardness of the wheel steel specimens ranged from 275 to 900 HVw. The selected of the rail steel samples of 345-455 HVr covers the possible hardness variations (350-405 HVr) of R65 type long rails produced on the standard ST RK 2432-2013 “Railway Rails Differentially Hardened and Non-heat-strengthened.” Technical Requirements. The optimal ratio of wheel/rail hardness, which ensures minimum wear due to weight loss of the tested samples, is the interval HVw/HVr–1.41-1.59. This ratio of wheel/rail hardness is practically confirmed when linear wear is determined by micrometric measurement of the impression size with HVw/HVr–1.39-1.56. The results of the laboratory tests and the suggestions for the optimal ratio of wheel/rail hardness to improve wear resistance should be verified under field conditions. Oscillography of the destruction process of plasma-hardened and non-strengthened specimens was performed to evaluate the resistance to crack initiation and propagation.

In the work improved system of equation of plane-parallel movement of the road train with single-axle O1-category trailer. Defined lateral reactions on the vehicle and trailer wheels at body roll, wheels slip caused by body roll and also developed road train spatial mathematical model in a transverse plane. This model is used to study the road train course stability with O1-category trailer. It is shown that the spatial model of road train with no vehicle and trailer wheels inclination has the same divergent instability characteristic as the plane road train layout.

Let $ T_{1}, T_{2}, \dots, T_{k} $ be spanning trees of a graph $ G $. For any two vertices $ u, v $ of $ G $, if the paths from $ u $ to $ v $ in these $ k $ trees are pairwise openly disjoint, then we say that $ T_{1}, T_{2}, \dots, T_{k} $ are completely independent. Hasunuma showed that there are two completely independent spanning trees in any 4-connected maximal planar graph, and that given a graph $ G $, the problem of deciding whether there exist two completely independent spanning trees in $ G $ is NP-complete. In this paper, we consider the number of completely independent spanning trees in some Cartesian product graphs such as $ W_{m}\Box P_{n}, \ W_{m}\Box C_{n}, \ K_{m, n}\Box P_{r}, \ K_{m, n}\Box C_{r}, \ K_{m, n, r}\Box P_{s}, \ K_{m, n, r}\Box C_{s} $.

This paper presents mathematical models to estimate the kinematics and dynamics of wheeled and tracked robots. The models account for the physical–mechanical characteristics of the ground, the influence of the center of gravity displacement on the cornering moment of resistance, and the influence of the interaction of the crawler with the roadway. The results of the models are characterized by defining computational relationships for a robot's equations of motion, longitudinal forces, transverse forces, and resistive turning moments generated via longitudinal forces and transverse forces. [ABSTRACT FROM AUTHOR]

While many studies have been used onboard monitoring methods to detect train wheel defects, this paper aims to extract damage features from vibrational signals obtained by the wayside monitoring system. To provide an appropriate tool for the decomposition of experimental nonstationary vibration signals containing impacts, an analytical amplitude-based signal decomposition method is provided. A two-axle motor car with a flat wheel defect is studied at different operating conditions. Vibrational signals arising from wheel-rail interactions are gathered by the Wayside Data Collection Setup (WDCS) with five piezoelectric accelerometers. The tests are performed at the constant speeds of 10, 20, 30, and 40 km/h. The acquired signals are decomposed by the Multi-channel Singular Spectrum Analysis (MSSA) into the contributing components. Based on the results, increases in the amplitudes of the second reconstructed components (RCs) of the vibrational signals sensed by all the accelerometers can be observed at a specific time instance as a repeating pattern. Similar patterns are obtained at different motor car positions relative to the measurement area, as well as different motor car speeds. To verify the consistency of the second RCs, the crest factors are obtained for all the angular positions. The results show sudden increases in the crest factor at a fixed angular position that indicate the existence of a defect at that specific angular position of the wheel. [ABSTRACT FROM AUTHOR]

This study is dedicated toward subtractive manufacturing of difficult to process material, Ti-6Al-4 V through an extensively employed precision abrasive machining operation, grinding. Ti-6Al-4 V is the most extensively used material, which needs grinding during its finishing in many cases. However, grinding of the material is challenging due to the characteristics like high chemical reactivity at higher temperature, high hot-hardness, low elastic modulus, and low thermal conductivity. Due to elevated reactivity at raised up temperature, titanium tends to adhere to the abrasive wheel during grinding thus leading to ineffective cutting performance. Its low thermal conductivity intensifies thermal damage to the bonded abrasives forming glazed grits. The present experimental study deals with finding optimum cutting conditions for enhancing grindability of the alloy that involves optimizing the grinding infeed values for different conventional wheels. The optimized dressing infeed is used in the subsequent grinding operation where enhancement of grinding condition is investigated under the application of cutting fluids. The major considerations of the study are identifying coolants and delivery techniques, which follow sustainable developments, and suitable conventional abrasive grinding wheels. [ABSTRACT FROM AUTHOR]

Wheels are structural components designed to sustain dynamic loads and avoid fatigue failures in service. For their validation, when standard fatigue tests are not feasible due to premature tyre wear, alternative methods should be used. In this paper, the rim section test approach is evaluated for the fatigue life assessment of steel rims for off-highway wheels. Customized specimens were studied by finite element analysis and subjected to bending fatigue tests to obtain the fatigue curve for the critical point of the rim. The results were also compared to fatigue data from standard tests of the base material, confirming the importance of testing components in conditions as similar as possible to the final ones in service. Additional measurements of the specimens' surface hardness showed how this approach is valid to consider the effects of possible work hardening induced in the components by the production process. The residual stress state, instead, does not seem to be considered appropriately, since the initial compressive residual stresses of the component were released during the manufacturing of the specimens. The overall results of the study confirmed the suitability of the section test approach as an alternative method for the fatigue life evaluation of structural components. Moreover, it could be used for specific investigations concerning the influence of the production process parameters on wheel rims. [ABSTRACT FROM AUTHOR]

The solvothermal reactions of LnCl3·6H2O and MCl2·6H2O (M = Co, Ni) with 2,2′-diphenol (H2L1) and 5,7-dichloro-8-hydroxyquinoline (HL2) gave three 3d–4f heterometallic wheel-like nano-clusters [Ln7M6(L1)6(L2)6(µ3-OH)6(OCH3)6Cl(CH3CN)6]Cl2·xH2O (Ln = Dy, M = Co, x = 3 for 1; Ln = Dy, M = Ni, x = 0 for 2; Ln = Tb, M = Ni, x = 0 for 3) with similar cluster structure. The innermost Ln(III) ion is encapsulated in a planar Ln6 ring which is further embedded in a chair-conformation M6 ring, constructing a Russian doll-like 3d–4f cluster wheel Ln(III)⸦Ln6⸦M6. 2 and 3 show obvious slow magnetic relaxation behavior with negligible opening of the magnetic hysteresis loop. Such a Russian doll-like 3d–4f cluster wheel with the lanthanide disc isolated by transition metallo-ring is rarely reported. [ABSTRACT FROM AUTHOR]

Different variants of the hardness of the wheel/rail friction pair were investigated to determine the optimal hardness range of the wheel/rail that ensures the minimum wear under selected test conditions. A pair of tests was performed on an MI-2 machine with a cylindrical wheel steel roller and a rail steel liner. The hardness of the wheel steel specimens ranged from 275 to 900 HVw. The selected of the rail steel samples of 345-455 HVr covers the possible hardness variations (350-405 HVr) of R65 type long rails produced on the standard ST RK 2432-2013 "Railway Rails Differentially Hardened and Nonheat-strengthened." Technical Requirements. The optimal ratio of wheel/rail hardness, which ensures minimum wear due to weight loss of the tested samples, is the interval HVw/HVr-1.41-1.59. This ratio of wheel/rail hardness is practically confirmed when linear wear is determined by micrometric measurement of the impression size with HVw/HVr-1.39-1.56. The results of the laboratory tests and the suggestions for the optimal ratio of wheel/rail hardness to improve wear resistance should be verified under field conditions. Oscillography of the destruction process of plasma-hardened and nonstrengthened specimens was performed to evaluate the resistance to crack initiation and propagation. [ABSTRACT FROM AUTHOR]

Let T 1 , T 2 , ... , T k be spanning trees of a graph G. For any two vertices u , v of G , if the paths from u to v in these k trees are pairwise openly disjoint, then we say that T 1 , T 2 , ... , T k are completely independent. Hasunuma showed that there are two completely independent spanning trees in any 4-connected maximal planar graph, and that given a graph G , the problem of deciding whether there exist two completely independent spanning trees in G is NP-complete. In this paper, we consider the number of completely independent spanning trees in some Cartesian product graphs such as W m ◻ P n , W m ◻ C n , K m , n ◻ P r , K m , n ◻ C r , K m , n , r ◻ P s , K m , n , r ◻ C s . [ABSTRACT FROM AUTHOR]

One of the important features of an interconnection network is its ability to efficiently simulate programs or parallel algorithms written for other architectures. Such a simulation problem can be mathematically formulated as a graph embedding problem. In this paper we compute the lower bound for dilation and congestion of embedding onto wheel-like networks. Further, we compute the exact dilation of embedding wheellike networks into hypertrees, proving that the lower bound obtained is sharp. Again, we compute the exact congestion of embedding windmill graphs into circulant graphs, proving that the lower bound obtained is sharp. Further, we compute the exact wirelength of embedding wheels and fans into 1,2-fault hamiltonian graphs. Using this we estimate the exact wirelength of embedding wheels and fans into circulant graphs, generalized Petersen graphs, augmented cubes, crossed cubes, Mobius cubes, twisted cubes, twisted n-cubes, locally twisted cubes, generalized twisted cubes, odd-dimensional cube connected cycle, hierarchical cubic networks, alternating group graphs, arrangement graphs, 3-regular planer hamiltonian graphs, star graphs, generalised matching networks, fully connected cubic networks, tori and 1-fault traceable graphs. [ABSTRACT FROM AUTHOR]

To determine the optimal range of hardness of the wheel rim strengthened layer and the rail head rolling surface, which provides an increase in wear resistance, the variants of hardness of the wheel-rail friction pair are studied. On a machine MI-2 in laboratory conditions, a pair of cylindrical roller-insert was tested under sliding friction. Hardness of wheel steel samples varied from 275 to 900 HVw. Samples of R65 rail steel were used as a counterbody, the hardness of which was in the range of 345–455 HVr. The hardened layer depth for wheel steel samples is ~1 mm. At the same time, the wheel–rail pair hardness ratios were chosen, which can be obtained in real rolling stock operating conditions, which brings the laboratory tests closer to production ones and is of practical importance. It is shown that the optimal range of wheel hardness is in the range of HV 557–672, i.e., the required wheel and rail hardness ratio HVw/HVr is in the range of 1.41–1.58. An increase in wheel hardness above 860–900 HV under actual operating conditions can lead to hardened layer spalling and cracking, as well as to intense rail wear. Hardening of rim and wheel flanges to a relatively low hardness of 275–505 HV is ineffective, since wear resistance improves slightly. It is noted that the results of laboratory tests and the expressed considerations on the optimal ratio of hardness of the wheel-rail friction pair to increase their wear resistance should be confirmed in the operating conditions. [ABSTRACT FROM AUTHOR]

The aim of this study is the evaluation of Life Cycle Sustainability Assessment (LCSA) visualizations, which have been gaining increasing relevance in recent years. Despite this, the final interpretation and visualization of LCSA are not yet sufficiently established. Three of the existing LCSA visualization tools, Life Cycle Sustainability Triangle (LCST), Life Cycle Sustainability Dashboard (LCSD), and Sustainability Crowns, are compared and discussed along previously established target criteria. Subsequently, a "new" visualization tool (LCSA-Wheel) is developed based on analysis results and tested within a case study. It became clear that the LCST and Sustainability Crowns are mainly used to help weigh the sustainability dimensions. Nevertheless, the Sustainability Crowns meet most of the defined target criteria and thus serve as a model for the development of a visualization approach. The LCSD maps a wealth of information but is more difficult to understand without a deeper dive into the topic. The proposed LCSA-Wheel adopts a clear structure and provides information needed to understand the visualization. Although further developments are still necessary for general applicability, there is a justified assumption, shown with the help of a case study, that the LCSA-Wheel will gain acceptance in science and practice and thus drive the use of the LCSA. [ABSTRACT FROM AUTHOR]

Background: Evidence-based medicine (EBM), as originally conceived, used all types of peer-reviewed evidence to guide medical practice and decision-making. During the SARS-CoV-2 Coronavirus disease (COVID-19) pandemic, the standard usage of EBM, modeled by the Evidence-Based Medicine Pyramid, undermined EBM by incorrectly using pyramid levels to assign relative quality. The resulting pyramid-based thinking is biased against reports both in levels beneath randomized control trials (RCTs) and those omitted from the pyramid entirely. Thus, much of the evidence was ignored. Our desire for a more encompassing and effective medical decision-making process to apply to repurposed drugs led us to develop an alternative to the EBM Pyramid for EBM. Herein, we propose the totality of evidence (T-EBM) wheel. Objectives: To create an easily understood graphic that models EBM by incorporating all peer-reviewed evidence that applies to both new and repurposed medicines, and to demonstrate its potential utility using ivermectin as a case study. Methods: The graphics were produced using Microsoft Office Visio Professional 2003 except for part of the T-EBM wheel sunburst chart, which was produced using Microsoft 365 Excel. For the case study, PubMed® was used by searching for peer-reviewed reports containing “ivermectin” and either “covid” or “sars” in the title. Reports were filtered for those using ivermectin-based protocols in the treatment of COVID-19. The resulting 265 reports were evaluated for their study design types and treatment outcomes. The three-ringed graphical T-EBM wheel was composed of two inner rings showing all types of reports and an outer ring showing outcomes for each type. Findings-Conclusions: The T-EBM wheel avoids the biases of the EBM Pyramid and includes all types of reports in the pyramid along with reports such as population and mechanistic studies. In both early and late stages of medical emergencies, pyramid-based thinking may overlook indications of efficacy in regions of the T-EBM wheel beyond RCTs. This is especially true when searching for ways to prevent and treat a novel disease with repurposed therapeutics before RCTs, safety assessments, and mechanisms of action of novel therapeutics are established. As such, T-EBM Wheels should replace the EBM Pyramids in medical decision-making and education. T-EBM Wheels can be expanded upon by implementing multiple outer rings, one for each different kind of outcome (efficacy, safety, etc.). A T-EBM Wheel can be created for any proprietary or generic medicine. The ivermectin (IVM) T-EBM Wheel displays the efficacy of IVM-based treatments of COVID-19 in a color-coded graphic, visualizing each type of evidence and the proportions of each of their outcomes (positive, inconclusive, negative).

The implementation of forces and moments applied to the wheels of a vehicle occurs in the zone of contact of the wheels with the supporting surface, and therefore the analytical determination of their force and kinematic parameters should be based on consideration of the phenomena occurring in contact. One of the directions for solving these problems is based on a technique based on the theory of preliminary displacement of wheel surface elements in the contact zone with the supporting surface and dividing the contact area into adhesion and sliding zones, which makes it possible to take a new approach to the consideration of wheel rolling mechanics. The use of this technique makes it possible to obtain relatively simple equations for such power and kinematic parameters of the wheel as the coefficient of rolling resistance, the coefficient of tangential elasticity of the wheel, and hysteretic losses in the wheel material. The derived equations contain a small number of parameters that can be easily determined experimentally and are convenient for both theoretical and practical use. Comparison of theoretical and experimental results with studies of other authors shows their relatively small discrepancy, which confirms the validity of the research methodology used, as well as the assumptions made.

In this study, a twin-disc test rig with an environmental control chamber was used to conduct experiments on the influence of ambient temperature and humidity on the adhesion and damage of CL60 wheel steel. The results indicated that the degree of wheel surface oxidation increased with increasing temperature under high humidity conditions. The formation of iron hydroxide on the surface increased friction and damaged the surface. As the relative humidity increased, the moisture in the generated oxide debris reached a saturated state, and the debris exhibited a pasty texture that significantly reduced adhesion. Under high humidity conditions, the plastic deformation layer of the wheel increased obviously. The depths and lengths of cracks that formed in the wheel under high humidity conditions were greater than those produced under medium and low humidity conditions. [ABSTRACT FROM AUTHOR]

In the work improved system of equation of plane-parallel movement of the road train with single-axle O1-category trailer. Defined lateral reactions on the vehicle and trailer wheels at body roll, wheels slip caused by body roll and also developed road train spatial mathematical model in a transverse plane. This model is used to study the road train course stability with O1-category trailer. It is shown that the spatial model of road train with no vehicle and trailer wheels inclination has the same divergent instability characteristic as the plane road train layout. [ABSTRACT FROM AUTHOR]