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This paper proposes a mechatronic suspension system with capabilities of energy regeneration and semi-active control [i.e., skyhook (SK)], incorporated into the mechanism. The system overcomes the trade-off between energy consumption and ride handling/comfort in a semi-active/active suspension system. Central to the concept is the development of a switched-mode rectifier (SMR) capable of providing either a positive or negative damping ratio by controlling the electric current to alternate between regenerative and motoring modes. Using the implemented circuit, a regenerative SK control strategy is utilized to provide a continuous variable damping force that significantly improves the vibration isolation. Simulation results are presented to demonstrate power flow in both regenerating and motoring modes by utilizing a current controller. Furthermore, experimental results are presented highlighting performance of the regenerative suspension prototype in terms of power regeneration, sprung mass absolute acceleration, and relative displacement. In addition, both theoretical and experimental power conversion efficiencies in various segments of the mechatronic suspension are analyzed and reported. [ABSTRACT FROM PUBLISHER]

A novel substrateless power amplifier module realized by ridge gap waveguide (RGW) technology is proposed in Ka-band. Up to our knowledge, this is the first time that an active device is directly integrated with an RGW structure. No substrate is used in the RF section of the implemented power amplifier and the whole structure is made by machining a piece of metal. The amplifier was made of two pieces and was easily assembled without needing a precise contact between the two sections. The cavity resonance of the amplifier is suppressed using a pining structure. The fabricated amplifier module is self-packaged and does not need any packaging. It is shown that the simulated and measured results are in good agreement. This paper shows the capability of RGW technology for implementing the whole RF frontend in microwave- and millimeter-wave systems. [ABSTRACT FROM PUBLISHER]

This paper investigated the potential applicability of the specification equation for the shear pull-out strength of a power-actuated fastener (PAF) connection to nail connections between steel sheets thinner than 2.9 mm. The tested G300, G450, and G550 specimens had thicknesses ranging from 0.6 to 2.4 mm, connected with 2.5- or 3.6-mm helically knurled nails. The pull-out strength is a function not only of the thickness of the member not in contact with the fastener head, but also of the other member's thickness. The member thicknesses have greater influence than the nail diameter on the pull-out strength, contrary to the design equation. Based on the test results of 93 shear nailed connections failing in pull-out, the paper proposes a design equation that is applicable to connections using helically knurled nails of steel sheets thinner than 2.9 mm. A group effect factor of 0.75 is suggested for serial nail connections based on the test results of 19 multiple nail connections. A resistance factor of 0.55 is recommended for use with the proposed equation for determining the pull-out strength of shear nailed connections in thin steel sheets. An additional finding is that the current design equation for the bearing and tilting strength of a PAF connection is applicable to connections in which the member not in contact with the fastener head is much thinner than the specification minimum of 3.2 mm, and in which the fastener diameter is smaller than the specification minimum of 3.7 mm. [ABSTRACT FROM AUTHOR]

Light gauge metal decking is commonly used in the building and bridge industries for concrete formwork. In addition to supporting the wet concrete, the metal forms also improve the lateral-torsional buckling capacity of the beams or girders they are fastened to since they behave as a shear diaphragm and restrain the warping deformation of the top flange. The design requirements for shear diaphragm bracing are not well established. This is the second part of a two-part paper. The first part of the paper focused on the general stability bracing behavior for shear diaphragms connected to the top flanges of adjacent beams or girders. This part of the paper outlines the design requirements for shear diaphragm bracing and focuses on both the stiffness and strength requirements for beam stability. Design expressions are presented for the stiffness and strength requirements as well as a model that can be used to estimate the forces in the fasteners that connect the diaphragms to the top flanges of the beams. An example is presented at the end of the paper demonstrating the use of the design expressions. [ABSTRACT FROM AUTHOR]

Disassembly is a vital step in any treatment stream of waste electrical and electronic equipment (WEEE), preventing hazardous and toxic chemicals and materials from damaging the ecosystem. However, the large variations and uncertainties in WEEE is a major limitation to the implementation of automation and robotics in this field. Therefore, the advancement of robotic and automation intelligence to be flexible in handling a variety of situations in WEEE disassembly is sought after. This paper presents an ontology-based cognitive method for generating actions for the disassembly of WEEE, with a focus on LCD monitors, handling uncertainties throughout the disassembly process. The system utilizes reasoning about relationships between a typical LCD monitor product, component features, common fastener types, and actions that the system is capable of, to determine 4 key stages of robotic disassembly: component identification, fastener identification, disassembly action generation, and identification of disassembly extent. Further uncertainties in the form of possible failure of action execution is reasoned about to provide new actions, and any unusual scenarios that result in incorrect reasoning outputs are rectified with user-demonstration as a last resort. The proposed method is trialed for the disassembly of LCD monitors and a product unknown to the system, in the form of a DVD-ROM drive. [ABSTRACT FROM AUTHOR]

This paper proposes a weighted large margin nearest center (WLMNC) distance-based human depth recovery method for tele-immersive video interaction systems with limited bandwidth consumption. In the remote stage, the proposed method highly compresses the depth data of the remote human into skeletal block structures by learning the WLMNC distance, which is equivalent to downsampling the human depth map at $64{\times}$ the sampling rate. In the local stage, the method first recovers a rough human depth map based on a WLMNC distance augmented clustering approach and then obtains a fine depth map based on a rough depth-guided autoregressive model to preserve the depth discontinuities and suppress texture copy artifacts. The proposed WLMNC distance is learned by the large margin clustering problem with a weighted hinge loss to balance the clustering accuracy and depth recovery accuracy and is verified to be able to preserve depth discontinuities between skeletal block structures with occlusion. A theoretical analysis is conducted to verify the effectiveness of using the weighted hinge loss. Furthermore, a novel data set containing various types of human postures with self-occlusion is built to benchmark the human depth recovery methods. The quantitative comparison with the state-of-the-art depth recovery methods on the introduced benchmark data set demonstrates the effectiveness of the proposed method for human depth recovery with such a high upsampling rate. [ABSTRACT FROM AUTHOR]

Controlled force–torque exertion by a small-scaled free-flying space robot will be potentially required for future on-orbit assembly missions. This paper presents a hybrid controller to achieve the desired end-effector motion and contact forces required for driving a screw into a floating target. Attitude of the spacecraft base is controlled simultaneously. Postcapture control to stabilize the entire system is also addressed in this paper. Simulation results have demonstrated the effectiveness of the proposed control laws. [ABSTRACT FROM AUTHOR]

The objective of this paper is to use electromagnetic-based computer-aided design (CAD) tools to investigate the maximum tuning range of channel filters, typically used in satellite payloads. Both circular and rectangular waveguide technologies are investigated. The results of the investigation show that single-mode rectangular waveguide implementations offer substantially wider tuning range, as opposed to classical dual-mode circular waveguide implementations. In addition to simulations, measurements are also presented indicating very good agreement with theory, thereby fully validating the CAD procedure. [ABSTRACT FROM PUBLISHER]

This paper is focused on the electrical and mechanical performance of aluminum-copper hybrid busbars subjected to corrosion over time. Two different types of hybrid busbars with joints produced by conventional fastening with M8 hexagonal socket head bolt-nut pairs made from medium carbon steel and by a new injection lap riveting process with semi-tubular rivets made from the material of the softer conductor are used and subjected to salt spray and electrochemical tests. Electrical resistance measurements performed on hybrid busbars taken from the corrosion testing cabinet at the end of each exposure period allow concluding that the new injection lap riveted hybrid busbars have a better electrical performance over time due to the elimination of fasteners with a higher electrical resistivity than aluminum and copper and to the elimination of the aluminum-steel and copper-steel galvanic pairs. The capability of the injection lap riveted hybrid busbars to withstand shear forces after corrosion testing also revealed to be adequate and like those of the original (uncorroded) hybrid busbars. [ABSTRACT FROM AUTHOR]

Under long-term temperature loading, long bridges stretch and deform, causing the beam and rail to move relative to each other. This phenomenon could cause a gradual slide of the rail relative to the fastener composite pad and ultimately results in the slipping out of the fastener pad at the end of the ballastless track bridge changes. The slipping out of the fastener composite pad changes the longitudinal resistance of the fastener and causes shock of the train on the rail structure due to direct contact between the rail and the tie, thus inhibiting the normal use of the line. In this paper, a reciprocating tensile test was carried out on a WJ-8 small resistance fastener to explore the breaking process of the fastener composite pad, identify the interaction mechanism of the fastener composite pad under the rail, and ultimately determine the influence of the pad on the longitudinal resistance of the fastener. The results show that the two factors that affect the longitudinal resistance of the fastener under reciprocating loading are the surface roughness and displacement of the fastener composite pad. While the surface roughness of the fastener composite pad is the main influencing factor in the early stage, the displacement of the composite pad has a greater impact on the later stage. The research results of this paper can provide an important reference for the maintenance and repair of ballastless track fasteners on bridges. [ABSTRACT FROM AUTHOR]

The electro-mechanical brake booster (EMBB) is a kind of mechatronic actuator, which is developed to suit the brake assist requirement of electric vehicles. In this paper, we report on the design of an EMBB system consisting of a dc motor, a two-state reduction of a gear and ball screw, a servo body, and a reaction disk. Considering the inconvenience of installation and high price of the pedal force sensor, we translate the control problem of brake power assist control to position tracking control. Meanwhile, a nonlinear control method for position tracking is presented to solve the problem of power assist braking, which is formalized as three parts: the steady-state control, feed-forward control based on reference dynamics, and state-dependent feedback control. The benefit of the nonlinear control method is that it offers a concise control law and performs well in engineering implementations. In addition, a second-order filter was designed to do the signal processing and obtain a higher-order derivative. Finally, the bench tests based on rapid control prototyping environment were designed and implemented to verify the performance of the controller. Test results show that both the position tracking performance and response time of the EMBB system performed well. [ABSTRACT FROM AUTHOR]

The performance of distance-based classifiers heavily depends on the underlying distance metric, so it is valuable to learn a suitable metric from the data. To address the problem of multimodality, it is desirable to learn local metrics. In this short paper, we define a new intuitive distance with local metrics and influential regions, and subsequently propose a novel local metric learning algorithm called LMLIR for distance-based classification. Our key intuition is to partition the metric space into influential regions and a background region, and then regulate the effectiveness of each local metric to be within the related influential regions. We learn multiple local metrics and influential regions to reduce the empirical hinge loss, and regularize the parameters on the basis of a resultant learning bound. Encouraging experimental results are obtained from various public and popular data sets. [ABSTRACT FROM AUTHOR]

Piezo-driven precision positioning platforms with large stroke are greatly demanded in both scientific research and industrial applications. Although various principles have been proposed to design piezo-driven positioning platforms, the problem of backward motion commonly exists, greatly hindering their applications. To suppress the backward motion, in this paper, an idea by generating a forward frictional force to balance the reversed frictional force was proposed. Correspondingly, a specific arc-shape flexure hinge was designed to generate the forward frictional force via its elastic recovery. To verify the feasibility of the proposed idea, a positioning platform with alterable initial gap between contact surfaces is designed by the parasitic motion principle (PMP). By measuring the output displacement under various initial gaps, a critical initial gap was identified, at which the positioning platform could output stepping displacement without backward motion. Under this critical initial gap, effects of driving voltage and frequency on the backward motion are further investigated. In addition, the natural frequency and loading capacity of the positioning platform are tested. This paper confirms that using PMP, it is feasible to design piezo-driven positioning platforms with completely suppressed backward motion, which would enhance the applications of the PMP and PMP positioning platforms. [ABSTRACT FROM AUTHOR]

Homodyne laser vibrometer plays an essential role in the precision vibration measurement, but its application is restricted when measuring subfringe vibration and targets with various reflectivities. In order to achieve the nanoscale vibration measurement and to adapt to various reflectivities, an enhanced homodyne laser vibrometer is presented in this paper. First, an active vibration mechanism (AVM) based on a flexure hinge stimulated by a piezoelectric transducer (PZT) is introduced into the reference arm, with which the parameters for nonlinear error correction can be predetermined, and thereby the measurement of vibration less than quarter wavelength is feasible. Second, an automatic gain module is employed to optimize the intensity of the interference signals, which significantly improves the adaptability to target reflectivity. The experimental results show that the laser vibrometer proposed is capable of measuring vibration with amplitude down to 2 nm and vibration with surface reflectivity down to 0.08%. [ABSTRACT FROM AUTHOR]

This paper addresses two fundamental problems: 1) learning discriminative model parameters and 2) avoiding over-fitting, which often occurs in regression-based classification tasks. We formulate these two problems in terms of relaxing both the strict binary label matrix and graph regularization term into more flexible forms so that the margins between different classes are enlarged as much as possible and the problem of over-fitting is avoided to some extent. This task is accomplished by the proposed double relaxed regression (DRR) method. The convex problem of DRR is solved efficiently with an iterative procedure. Extensive experiments on synthetic and real world image data sets demonstrate the effectiveness of the proposed method in terms of both classification accuracy and running time. [ABSTRACT FROM AUTHOR]

The lift leveling mechanism provided in this paper is controlled by the special rope fastening. By using the lift leveling mode controlled by the rope fastening, the leveling mode of the lifting system can be changed to the braking stop of the drive system after the platform is lowered and placed on the bracket. The problem of anchorage precision and the vibration caused by elastic expansion of the rope during platform loading and unloading are effectively solved by using the supporting function of the piers. In the process of studying this problem, we simplified a heavy-duty elevator system to form a simplified model that can be used for simulation research. The device provided in this article provides a new solution for the leveling of the heavy-duty lifting system, which not only ensures the leveling accuracy of the lifting platform during loading and unloading, but also effectively reduces the impact during leveling, which has a beneficial guiding effect on this type of equipment. [ABSTRACT FROM AUTHOR]

In this paper, the Lie symmetry method and Lie brackets of vector fields are used in order to find some new solutions of (3+1)-dimensional sourceless wave equation. The obtained solutions are classified to two categories; polynomial and non-polynomial exact solutions. Because of the properties of the Lie brackets and the symmetries, a generalized method is implemented for constructing new solutions from old solutions. We demonstrate the generation of such polynomial and non-polynomial solutions through the medium of the group theoretical properties of the equation. It is noteworthy that this method could be used when the equations have two special kinds of symmetries which will be mentioned below. [ABSTRACT FROM AUTHOR]

Support vector machines (SVM) have drawn wide attention for the last two decades due to its extensive applications, so a vast body of work has developed optimization algorithms to solve SVM with various soft-margin losses. To distinguish all, in this paper, we aim at solving an ideal soft-margin loss SVM: $L_{0/1}$ L 0 / 1 soft-margin loss SVM (dubbed as $L_{0/1}$ L 0 / 1 -SVM). Many of the existing (non)convex soft-margin losses can be viewed as one of the surrogates of the $L_{0/1}$ L 0 / 1 soft-margin loss. Despite its discrete nature, we manage to establish the optimality theory for the $L_{0/1}$ L 0 / 1 -SVM including the existence of the optimal solutions, the relationship between them and P-stationary points. These not only enable us to deliver a rigorous definition of $L_{0/1}$ L 0 / 1 support vectors but also allow us to define a working set. Integrating such a working set, a fast alternating direction method of multipliers is then proposed with its limit point being a locally optimal solution to the $L_{0/1}$ L 0 / 1 -SVM. Finally, numerical experiments demonstrate that our proposed method outperforms some leading classification solvers from SVM communities, in terms of faster computational speed and a fewer number of support vectors. The bigger the data size is, the more evident its advantage appears. [ABSTRACT FROM AUTHOR]

Kernel-based methods for support vector machines (SVM) have shown highly advantageous performance in various applications. However, they may incur prohibitive computational costs for large-scale sample datasets. Therefore, data reduction (reducing the number of support vectors) appears to be necessary, which gives rise to the topic of the sparse SVM. Motivated by this problem, the sparsity constrained kernel SVM optimization has been considered in this paper in order to control the number of support vectors. Based on the established optimality conditions associated with the stationary equations, a Newton-type method is developed to handle the sparsity constrained optimization. This method is found to enjoy the one-step convergence property if the starting point is chosen to be close to a local region of a stationary point, thereby leading to a super-high computational speed. Numerical comparisons with several powerful solvers demonstrate that the proposed method performs exceptionally well, particularly for large-scale datasets in terms of a much lower number of support vectors and shorter computational time. [ABSTRACT FROM AUTHOR]

The development of high-strength fasteners is required due to the modern trend of reducing the weight of engineering structures. At present, structural bolts of property classes 8.8–10.9 are widely used, and higher-strength bolts of property classes 12.9 and 14.9 are being developed. In this paper, we analyzed the possibilities and conditions for manufacturing fasteners of different strength categories from steels of seven grades, containing and not containing boron. The necessary corresponding temperature ranges of processing are determined based on the study of hot-rolled round steel. Tensile strength, yield strength, relative elongation, reduction in area, and Vickers microhardness were measured. An analysis was made of the hardenability and the influence of the holding time during tempering on the mechanical properties of the considered round steel. Using the method of scanning electron microscopy, the effect of carbide precipitation during tempering on the mechanical properties of fasteners was established. [ABSTRACT FROM AUTHOR]

Fastening systems play a significant role in railroad track dynamics. In this paper, three approaches are investigated for rail fastenings modeling using FEM: (1) spring–damper pairs covering the areas representing the fastening connections; (2) a solid-load approach that explicitly models the solid baseplates and includes toe loads by applying external loads; and (3) a solid-spring approach that takes into account the coupling of rail with the ties by using prestressed springs. Experimental tests were carried out to evaluate the performance of the FEM models. The mode shapes obtained from the FEM models and the experiments were used for the evaluation. A measurement quantifying the similarity of the mode shapes was proposed, which considers both shape similarity and distance similarity. The results showed that the rail foot's mode shapes obtained from the model using the spring–damper approach demonstrated the most similarity with the ones obtained from the experiments. [ABSTRACT FROM AUTHOR]

The existing pre-joining processes optimization methods divide the panel into many units, and then absolutely optimize the pre-joining processes for these units, which do not take into account the influence of the clearances flow among units on the determination of pre-joining processes. To solve the abovementioned problem, this paper presents an optimized method of pre-joining processes for panel to establish the processes correlation among units, by considering the clearances flow among units based on the optimization of pre-joining processes for units. Firstly, take the pre-joining path optimization and the less residual clearances as the combined aims, consider the panel structure and the space constraints as conditions, and establish a planning model of pre-joining sequences among units of panel. Afterwards, based on the pre-joining sequences of units of the panel, analyze the influence of pre-joining of the current unit on the clearances of adjacent unit; set up a calculation model of clearances flow among units; subsequently, build up the pre-joining model for units with meeting to permissive clearances after pre-joining, to optimize the number, location, and sequence of pre-joining points for units; and finally, based on abovementioned models, present an optimization method of pre-joining processes orienting to the clearances suppression of units and the clearances flow among units. The effectiveness of the proposed method in the current paper was verified by a pre-joining example. The result has shown that (1) based on the previous study of pre-joining only for units, the current paper has proposed the model of clearances flow among units, and the prediction error of this model is 10% comparing with the experiment value; (2) according to the optimized pre-joining sequence among units and the finite element simulation of clearances flow among units, the pre-joining affection of the current unit will lead to that the initial clearances of the adjacent unit has a slight increase by 9%, and there is no problem of wrinkle for the panel in that the clearances flow out; and (3) the proposed method has took the units of panel as the object, studied the mechanisms for the clearances suppression of units and the clearances flow among units, and established the optimization manner of pre-joining processes for the panel to reduce the clearances of panel and the number of pre-joining points. [ABSTRACT FROM AUTHOR]

This paper presents a miniature 50 mm3 inertial measurement unit (IMU) implemented using a folded microelectromechanical systems (MEMS) process. The approach is based on wafer-level fabrication of high aspect-ratio single-axis sensors interconnected by flexible hinges and folded into a 3-D configuration, like a silicon Origami [1]. Two different materials for flexible hinges have been explored, including photo-definable polyimide and parylene-C. We report, for the first time, an IMU prototype with seven operational sensors: three accelerometers, three gyroscopes, and a prototype of a reference clock. This paper concludes with the results of experimental characterization of inertial sensors demonstrating the feasibility of the proposed approach for a compact IMU. [2016-0267] [ABSTRACT FROM AUTHOR]

A hydraulic load cell is a simple onsite load measurement device for quality assurance of structural fasteners. While these load cells can be used to establish torque-tension relationship, due to their reduced stiffness compared to electronic load cells, prominent standards such as EN14399-2 prevents the use of hydraulic load cells in bolt assemblies testing where nut rotational angle is also of importance. Since the significant angular parameter used in EN14399-2 is a difference of two angles, it can be argued that when the difference of angle is considered, the reduced stiffness effect of hydraulic load cell could be negated. This paper provides both theoretical and experimental validation of using an electronic and a hydraulic load cell to carry out the fit-for-purpose assembly test as prescribed in EN14399-2. Results show that a hydraulic load cell can be used as a simple onsite screening test to improve quality assurance of structural bolt assemblies on construction sites. The Australian Standard for fastener assemblies AS/NZS 1252:2016 requires a test regime to ensure the supplied bolts are suitable for its intended application. The methodology developed in this paper maybe used to screen the quality of the supplied fasteners on-site before being used in the assembly. [ABSTRACT FROM AUTHOR]

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The virtual track train (VTT) is a new type of urban transit system with all-wheel active steering technology utilized to make the long combination vehicle run along the planned route (virtual track) like railway vehicles along physical track. This paper proposed a scalable cascade modular path following control strategy for the newly designed gantry virtual track train (G-VTT) based on preview & tracking controller, focusing on the lateral control for low-speed turning manoeuvre. The mathematical characteristics of the 2-norm was utilized to establish a local tracking objective function (LTOF) to find the optimal lateral acceleration (OLA) of the tracking point in the preview window and calculate the optimal wheel steering angle (WSA) to achieve the optimal local trajectory. Considering the lag time Td, the yaw stability and path following ability of the vehicle are contradictory in some cases, so the damping adjustment factor λ was proposed to optimize the damping characteristics and the time-delay stability factor ξ was proposed to evaluate the time-delay stability. The influence of the key parameters, preview time Tp, Td, ξ and λ, on the stability and following ability were analyzed by frequency domain analysis method, and the optimal region of ξ and λ was obtained to instruct the configuration of λ and Tp. Finally, steady-state and dynamic forward predictive models were proposed to compensate for the oscillation caused by the lag time. The effectiveness of the proposed control strategy, forward predictive models and the configuration method of λ and Tp were verified by theoretical analysis and numerical simulation. [ABSTRACT FROM AUTHOR]

In this paper, we propose a general framework termed centroid estimation with guaranteed efficiency (CEGE) for weakly supervised learning (WSL) with incomplete, inexact, and inaccurate supervision. The core of our framework is to devise an unbiased and statistically efficient risk estimator that is applicable to various weak supervision. Specifically, by decomposing the loss function (e.g., the squared loss and hinge loss) into a label-independent term and a label-dependent term, we discover that only the latter is influenced by the weak supervision and is related to the centroid of the entire dataset. Therefore, by constructing two auxiliary pseudo-labeled datasets with synthesized labels, we derive unbiased estimates of centroid based on the two auxiliary datasets, respectively. These two estimates are further linearly combined with a properly decided coefficient which makes the final combined estimate not only unbiased but also statistically efficient. This is better than some existing methods that only care about the unbiasedness of estimation but ignore the statistical efficiency. The good statistical efficiency of the derived estimator is guaranteed as we theoretically prove that it acquires the minimum variance when estimating the centroid. As a result, intensive experimental results on a large number of benchmark datasets demonstrate that our CEGE generally obtains better performance than the existing approaches related to typical WSL problems including semi-supervised learning, positive-unlabeled learning, multiple instance learning, and label noise learning. [ABSTRACT FROM AUTHOR]

The prefabricated construction industry, also known as off-site construction, has been operating in North America for several years now and differs from traditional construction in its much shorter project timelines, lower costs, and increased build quality. However, the lack of a suitable and efficient assembly solution has been identified by many as a barrier to the use of off-site construction for larger buildings. To maximise the benefits of off-site manufacturing for multistorey buildings, an automated connection solution is presented in this paper. A new plug-in self-locking device was developed according to the following product design phases: on-site observations, definition of the problem and product specifications, solution generation, prototyping, fabrication, and testing. The plug-in self-locking device allows the assembly process to be accelerated by eliminating the fastening steps and a higher completion of modules off-site to be achieved. The design bears the compressive, tensile, and shear loads and contributes to the load path of the building. [ABSTRACT FROM AUTHOR]

This paper introduces the concept of the trans-rotary magnetic gear (TROMAG). The TROMAG is a magnetic device consisting of a rotor and a translator with an air gap in between, capable of converting linear motion to rotation, and vice versa, and doing the gearing action at the same time. Although its structure suggests that the TROMAG is simply the magnetic dual to the mechanical lead-screw, the authors show that the concept could also be derived from the elementary magnet arrays. The paper tries to establish an analogy between the TROMAG and the ordinary electrical machines with respect to the number of poles and the stack length, thus providing a deeper insight into the device operation. Three-dimensional (3-D) finite element analysis (FEA) is deployed to obtain the torque and force characteristics. Furthermore, it is shown that in addition to the permanent magnet (PM) TROMAG, developing the reluctance and the induction TROMAG is possible as well, but at a lower force density. [ABSTRACT FROM AUTHOR]

Since robotics is becoming increasingly widespread in the construction industry, more phases and working steps should be investigated for their applicability to automation. Ideally, only few robot systems would be needed and thus be multifunctional. Current robot systems are used almost exclusively in precast construction. At the construction site, only prototypes are in use, and only individual parts of the building shell construction and assembly can be handled. This paper examines to what extent robots can be applied for the installation of fastenings and which boundary conditions exist or need to be addressed. Automated construction, and more precise installation of fastenings, has been partially implemented, which has been shown to increase productivity as well as installation quality, and therefore the components' structural safety. This knowledge must now be extended to robots. The present work is based on an overview of current research and development and includes a discussion on the current research at the University Duisburg-Essen on a cable robot for brickwork construction. It further demonstrates that fastenings pose an important additional application, especially to ensure the changeover to other building materials. These can be built-in parts, but also brickwork connections or prefabricated parts. It can be assumed that robots will become increasingly important in the construction industry for reasons that include high quality, safety, speed and economic aspects. This is an extended paper of the Creative Construction Conference in Budapest on "Examination of Advanced Fastening Systems for the use of Robots in the Construction Industry" (Spyridis et al., 2019). [ABSTRACT FROM AUTHOR]

The most important components of the internal nut thread inspection process are measuring the pitch and pitch diameter value and comparing these with their respective specifications, as a test nut is considered to be abnormal when its pitch or pitch diameter does not meet specifications. This paper focuses on defects arising when the pitch diameter does not meet its specification. Because conventional contact strategies are not suited to the real-time inspection of internal thread defects, there have been a number of recent attempts to develop noncontact methods for real-time measurement. Some approaches have applied laser triangulation techniques in which reflected light is used to measure the z-axis depth on an object’s surface. Although point lasers have been shown to be highly precise in measuring pitch diameter, the optical architecture involved in these approaches is complicated and, as the laser must be scanned in a pointwise manner to derive cross-sectional measurements, the measurement process is too long to be compatible with real-time defect inspection. In this papere, an image-based method employing a line laser projector was used to develop a real-time image-based nut pitch diameter defect inspection system. The proposed method, which improves upon the conventional, widely used template-matching method for rapid defect detection, was shown to be effective through experimental validation. [ABSTRACT FROM AUTHOR]

This paper introduces a new type of reluctance-based magnetic lead screw (RBMLS) that is attractive for many potential applications. The proposed topology presents the implementation of discretized permanent magnets (PMs) and ferromagnetic semi-rings. The proposed RBMLS has PMs in only one of its movable parts, making it suitable for long-stroke applications. The proposed RBMLS is analyzed through the 2-D and 3-D finite-element method in order to test its topology and obtain the force produced per PM volume. Detailed design features are presented for the realization of a prototype. [ABSTRACT FROM AUTHOR]

Heavy-haul railway has been developed rapidly in many countries in the world due to its great social and economic benefits. One of the key technologies for heavy-haul railway is the reduction of vibration on the track structures and its surrounding due to impact load induced by the train in service. The vibration behaviors of two kinds of low-vibration track (LVT) systems for heavy-haul railway are investigated in this paper. Firstly, two indoor full-scale low-vibration track models (new LVT and traditional LVT), which include rail, fastener, bearing block, rubber boot, track slab, and foundation base, were constructed according to design drawings. Secondly, the vibration responses of the different track components under the impact excitation of a dropping wheelset were measured. Thirdly, the time-domain characteristics of each track component of the two LVTs were compared by the acquired vibration time-history curves. Finally, the frequency-domain distribution was analyzed, and the vibration reduction performance was evaluated by the comprehensive time-frequency analysis results. The results show the new LVT has lower vibration acceleration, shorter duration of vibration period, lower vibration frequency of track components, and most importantly an obvious vibration reduction effect on the ground. The research results are useful to further optimize the design of LVT to reduce the vibration under train impact load. [ABSTRACT FROM AUTHOR]

This paper reports on a unique tactile microprobe based on a parallelogram kinematic made from monocrystalline silicon. This kinematic, made out of an orthogonal cascade assembly of three identical parallelograms, provides an isotropic behavior to the microprobe. Each parallelogram deflects in only one direction thanks to thin elastic silicon membrane hinges and their displacements are recognized using piezoresistors integrated into these hinges. Wide deflection ranges, isotropic behavior, and low mechanical stiffness of the new microprobe, as predicted by simulations, could be verified in experiments. The fabrication, the assembly, and the contacting of the first microprobe prototype was optimized to allow very compact integration into a Ø11 mm housing. This make it suitable for metrology research laboratories and industries equipped with conventional coordinate measurement machines and even for a variety of other 3-D force/displacement measurements. [2018-0157] [ABSTRACT FROM AUTHOR]

The estimation of the frictional and clamping forces is one of the key issues in the design and implementation of the electromechanical brake (EMB) system. In this paper, a clamping-force control algorithm is presented along with a consideration of the frictional characteristics and the estimation of the clamping force for a planetary reduction gear-type EMB. The frictional model is developed by including the frictional effect of the motor, the planetary gear, and the screw thread. Since the clamping-force estimation requires the distance of the contact gap between the pad and the disk, an initial gap-distance control algorithm that uses the gradient change of the motor torque is proposed. This paper is concluded with a discussion of the performance of the control algorithm by comparing the simulation results with the experimental results. [ABSTRACT FROM PUBLISHER]

This paper reports on the behavior of simply supported (I-shaped cross section) steel beams prestressed by tendons. It is well known that this typology of beams has successfully been used mainly in the past. Prestressed steel beams are lighter than traditional ones that have the same length and vertical load capacity; this aspect could make them economically advantageous and a viable solution in many practical situations. This paper analyzes prestressed steel beams having a medium span ranging from 35 to 45 m and which are to be used as roof structural elements. This study focuses on two parameters that are considered two of the fundamental items for the design: the number of deviators and the value of the prestressing force. This study has been carried out with nonlinear finite-element analyses that take into account both mechanical and geometrical nonlinearities. In particular, the behavior of these beams has been investigated up to failure during tensioning and during loading (after tensioning). The effect on the structural response of bracing, which can be only at the top flange of the beams or at the top and bottom flanges of the beams, also has been considered. [ABSTRACT FROM AUTHOR]

Rail fasteners are among the key components of ballasted track of high-speed railway due to their functionality of fixing rails to sleepers. The failure of rail fastening system hinders the transmission of train loads to underlying track substructure and therefore endangers the operation safety and longevity of ballasted track. This paper first established a three-dimensional (3D) numerical model of the train-ballasted track-subgrade coupling system by integrating multibody dynamics (MBD) and finite element method (FEM). Numerical simulations were then performed to investigate the effects of different patterns of rail fastener failure (i.e., consecutive single-side, alternate single-side, and consecutive double-side) on critical dynamic responses of track structures, train running stability, and operation safety. The results show that the resulting influences of different patterns of rail fastener failure descend in the order of consecutive double-side failure, consecutive single-side failure, and alternate single-side failure. As the number of failed fasteners increases, the range where dynamic responses of track structures are influenced extends, and the failure of two consecutive single-side fasteners exerts a similar influence as that of four alternate single-side fasteners. The failure of single-side fasteners affects dynamic responses of the intact side of track structures relatively insignificantly. The influence of rail fastener failure on track structures exhibits hysteresis, thus indicating that special attention needs to be paid to locations behind failed fasteners during track inspection and maintenance. The occurrence of the failure of two or more consecutive fasteners demands timely maintenance work in order to prevent aggravated deterioration of track structures. The findings of this study could provide useful reference and guidance to smart track condition assessment and condition-based track maintenance. [ABSTRACT FROM AUTHOR]

In many real-world applications, different types of misclassification usually suffer from different costs, but the accurate cost is often hard to be determined and usually one can only get an interval-estimation like that one type of mistake is about 5 to 10 times more serious than the other type. On the other hand, there are usually abundant unlabeled data available, leading to great research effort about semi-supervised learning. It is noticeable that cost interval and unlabeled data usually appear simultaneously in practice tasks; however, there is rare study tackling them together. In this paper, we propose the cisLDM approach which is able to handle cost interval and exploit unlabeled data in a principled way. Rather than maximizing the minimum margin like traditional large margin classifiers, cisLDM tries to optimize the margin distribution on both labeled and unlabeled data when minimizing the worst-case total-cost and the mean total-cost simultaneously according to the cost interval. Experiments on a broad range of datasets and cost settings exhibit the impressive performance of cisLDM. In particular, cisLDM is able to reduce 47 percent more total-cost than standard SVM and 27 percent more total-cost than cost-sensitive semi-supervised SVM which assumes the true cost value is known in advance. [ABSTRACT FROM PUBLISHER]

Simulation of flaw detection by eddy-current testing requires the calculation of the eddy-current signal due to the presence of the flaw. In this paper, the surface integral method (SIM) is applied for the calculation of the crack signal in the workpieces composed of a conducting plate with a borehole. The adopted approach makes use of Green’s operator that takes into account the effect of the borehole, and thus, the integral formalism is restricted to the crack surface only. The truncated region eigenfunction expansion method is followed for the construction of Green’s operator. Comparisons of the computed crack signal with numerical simulations carried out using a hybrid volume integral method-SIM approach and experimental results show excellent agreement. [ABSTRACT FROM AUTHOR]

The fastener system is an essential component of the high-speed ballastless track system. A detailed analysis for the effect of fastener looseness on the vertical dynamic response of the vehicle–track coupling system is conducted from the time domain, frequency domain and time–frequency domain in this paper. A fine fastener system model is employed, which includes two spring rods and one rail pad. The preloaded force is proposed to simulate the defect of the fastener, and a looseness coefficient is defined to represent the loose degree of the fastener. First, three fastener system models are introduced into the model, respectively, and the difference in the vehicle–track dynamic is analyzed and compared. The results show that the proposed model is more consistent with the real situation and more suitable to simulate fastener defects. Then, the detailed analysis of vehicle and track dynamic responses is explored in the case of different degrees of loose fasteners and the case of completely loose fasteners. According to the simulation results, there is little impact on the dynamic response of the vehicle–track system when the looseness coefficient is less than 0.9. When the fasteners are completely loosened, the dynamic response of the wheelset and the rail significantly increases. The vibration responses of rail and wheelset enhance with the increase of the number of the completely loose fastener. The loose fasteners affect the low-frequency part of the wheelset vibration response and the high-frequency part of the rail vibration response. Finally, a time–frequency analysis method is used to analyze the system vibration response under the combined effect of the completely loose fastener and the track irregularity. The track irregularity still dominates the excitation of the system, and the vibration response of the wheelset and the rail is more sensitive to the fastener defect at low speed. [ABSTRACT FROM AUTHOR]

In this paper, innovative ocean wave power takeoff (PTO) system is presented to enhance the electrical energy generation from oscillating wave motions. This PTO system, mainly consisting of dual-ball screws, a gearbox with mechanical motion rectification and a permanent magnet synchronous generator (PMSG), can convert bidirectional irregular motions from a floating wave buoy into unidirectional steady generator rotations. Systematical operating principles, design, and prototyping details of the PTO system are presented and analyzed. A hydrodynamic–mechanical–electrical model of the system is established by reasonably representing power switches attached to the PMSG as an equivalent external resistance. The overall dynamics of the system are then analyzed in the frequency domain. Three power control strategies are proposed to maximize the wave power absorption by changing the equivalent external resistance. The effectiveness and relatively high-energy conversion efficiency of the PTO system have been demonstrated based on lab bench test results. The levelized cost of energy of a full-scale wave energy converter system is also calculated based on the proposed PTO system. [ABSTRACT FROM AUTHOR]

HL-2M, the satellite tokamak of ITER (International Thermonuclear Experimental Reactor), has successfully completed the first plasma experiment in December 2020 in Southwestern Institute of Physics, China National Nuclear Corporation (CNNC-SWIP). The 500 W/4.5 K helium cryogenic system used in HL-2M is mainly used to cool down the cryopumps and superconducting magnets. The refrigeration system is the heart components of the cryogenic system. The design and development of the refrigeration system witness our significant cooperation with Fullcryo Company. The refrigeration system has completed the factory commissioning and on-site installation at the end of 2019. This paper presents the performance characteristics of the main key equipment in the system. [ABSTRACT FROM AUTHOR]

Relational topic models (RTMs) provide a probabilistic generative process to describe both the link structure and document contents for document networks, and they have shown promise on predicting network structures and discovering latent topic representations. However, existing RTMs have limitations in both the restricted model expressiveness and incapability of dealing with imbalanced network data. To expand the scope and improve the inference accuracy of RTMs, this paper presents three extensions: 1) unlike the common link likelihood with a diagonal weight matrix that allows the-same-topic interactions only, we generalize it to use a full weight matrix that captures all pairwise topic interactions and is applicable to asymmetric networks; 2) instead of doing standard Bayesian inference, we perform regularized Bayesian inference (RegBayes) with a regularization parameter to deal with the imbalanced link structure issue in real networks and improve the discriminative ability of learned latent representations; and 3) instead of doing variational approximation with strict mean-field assumptions, we present collapsed Gibbs sampling algorithms for the generalized relational topic models by exploring data augmentation without making restricting assumptions. Under the generic RegBayes framework, we carefully investigate two popular discriminative loss functions, namely, the logistic log-loss and the max-margin hinge loss. Experimental results on several real network datasets demonstrate the significance of these extensions on improving prediction performance. [ABSTRACT FROM AUTHOR]

This paper investigates mechanical and magnetic losses in a magnetic lead screw (MLS). The MLS converts a low-speed high-force linear motion of a translator into a high-speed low-torque rotational motion of a rotor through helically shaped magnets. Initial tests performed with a novel 17-kN demonstrator and a simplified motor model showed an efficiency of only 80% at low load; however, it was expected that the efficiency should be above 95%. For understanding and future optimization, a detailed study of the loss in the MLS is presented with the aim of identifying and segregating various loss components that was not accounted for in previous results. This is done through theoretical loss calculations and various experiments. It is concluded that the linear guide is the dominating loss component in the MLS demonstrator, whereas the losses in the axial thrust bearing is not as dominant as expected; furthermore, an efficiency above 94% was measured. [ABSTRACT FROM PUBLISHER]

Force-controllable actuators are essential for guaranteeing safety in human–robot interactions. Magnetic lead screws (MLSs) transfer force without requiring contact between parts. These devices can drive the parts with high efficiency and no frictional contact, and they are force limited when overloaded. We have developed a novel MLS that does not include spiral permanent magnets and an MLS-driven linear actuator (MLSDLA) that uses this device. This simple structure reduces the overall size of the device and improves productivity because it is constructed by a commonly used machined screw as a screw. The actuator can drive back against an external force and it moves flexibly based on the magnetic spring effect. In this paper, we propose a force estimation method for the MLSDLA that does not require separate sensors. The magnetic phase difference, as measured from the angular and linear displacements of the actuator, is used for this calculation. The estimated force is then compared against measurements recorded with a load sensor in order to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

We demonstrate a micro-electro-mechanical systems (MEMS) beam scanner capable of biaxial scanning with simultaneous focus control, for integration into a handheld confocal microscope for skin imaging. The device is based on a dual-axis gimbal structure with an integrated large-stroke deformable mirror. SU-8 polymer is used to construct both the deformable membrane as well as the torsional hinges for biaxial scanning. The 4-mm-diameter mirror can perform raster pattern scanning with a range of +/−1.5° and Lissajous scanning with a range of +/−3° (mechanical scan angle), and has a maximum deflection of $9~\mu \text{m}$ for focus control. The design, fabrication, and characterization of the opto-mechanical performance of the MEMS device are presented in this paper. [2018-0074] [ABSTRACT FROM AUTHOR]