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This paper presents a novel approach for tuning substrate integrated waveguide resonators, realized by placing an additional metallized via-hole on the waveguide cavity. The approach presented here can be applied as a trimming technique, as well as to develop filter designs with tunable center frequencies and tunable bandwidths. Three different filters are designed and implemented, demonstrating excellent trimming, 10% tuning of the center frequency, and 100% tuning of the bandwidth, respectively. [ABSTRACT FROM PUBLISHER]

Rare class problems are common in real-world applications across a wide range of domains. Standard classification algorithms are known to perform poorly in these cases, since they focus on overall classification accuracy. In addition, we have seen a significant increase of data in recent years, resulting in many large scale rare class problems. In this paper, we focus on nonlinear kernel based classification methods expressed as a regularized loss minimization problem. We address the challenges associated with both rare class problems and large scale learning, by 1) optimizing area under curve of the receiver of operator characteristic in the training process, instead of classification accuracy and 2) using a rare class kernel representation to achieve an efficient time and space algorithm. We call the algorithm RankRC. We provide justifications for the rare class representation and experimentally illustrate the effectiveness of RankRC in test performance, computational complexity, and model robustness. [ABSTRACT FROM PUBLISHER]

This paper presents the development of a novel regenerative shock absorber sized for a passenger car suspension system. The shock absorber includes a simple and highly efficient motion converter called a two-leg mechanism , a planetary gearhead, and a brushless three-phase rotary machine. The design and analysis of the regenerative shock absorber are presented by considering the dynamics and efficiency of the electromechanical device. The performance of the regenerative damper is evaluated under sinusoidal excitation inputs for typical amplitudes and frequencies in a vehicular suspension system. Experimental results show that a damping coefficient of $1720$ N$\cdot$s/m can be achieved by controlling the external loads. Furthermore, a mechanical energy conversion efficiency between 0.71 and 0.84 is achieved, which is considerably higher than other mechanisms reported in the literature, such as ball screw, rack-and-pinion, and linear mechanisms. [ABSTRACT FROM PUBLISHER]

The detection of fastener defects is an important task for ensuring the safety of railway traffic. The earlier automatic inspection systems based on computer vision can detect effectively the completely missing fasteners, but they have weaker ability to recognize the partially worn ones. In this paper, we propose a method for detecting both partly worn and completely missing fasteners, the proposed algorithm exploits the first and second symmetry sample of original testing fastener image and integrates them for improved representation-based fastener recognition. This scheme is simple and computationally efficient. The underlying rationales of the scheme are as follows: First, the new virtual symmetrical images really reflect some possible appearance of the fastener; then the integration of two judgments of the symmetrical sample for fastener recognition can somewhat overcome the misclassification problem. Second, the improved sparse representation method discarding the training samples that are “far” from the test sample and uses a small number of samples that are “near” to the test sample to represent the test sample, so as to perform classification and it is able to reduce the side-effect of the error identification problem of the original fastener image. The experimental results show that the proposed method outperforms state-of-the-art fastener recognition methods. [ABSTRACT FROM AUTHOR]

This paper describes the failure analysis of propeller blade fastening bolts made from martensitic stainless steel 0Cr16Ni5Mo, which was ruptured under service of cathode protection for 5 years. The general crack pattern of the bolts, fractographic features, hydrogen content determination and slow tensile test results are all exhibiting the characteristics of hydrogen embrittlement. Accordingly, hydrogen diffusion driven by hydrogen concentration gradient and stress concentration was identified by experiment and finite element analysis (FEA). The morphology of the crack was intergranular of initiation from bolt cap root surface, and quasi-cleavage of propagation. The hydrogen distribution indicated that the hydrogen concentration in the bolt was in gradient distribution, and the region farther away from the sea water contains less hydrogen content. This revealed that hydrogen entered the bolt top surface through sea water under cathodic protection, and diffused from top to cap. The hydrogen content of the cap where crack initiated was 7.0 ppm, which was much higher than that in bolt shaft with normal content of 1.1 ppm. Results of low tensile test together with fractographic observation showed that the brittleness of the bolt was enhanced by the effect of hydrogen. Stress distribution calculated by FEA analysis indicated that the maximal stress of the bolt was about 1016 MPa, located at cap root surface which was consistent with crack initiation sites. The stress drove hydrogen to accumulate at root surface until cracking occurred. In a sum, the failure was attributed to the hydrogen diffusion, local high stress, and the martensitic microstructure susceptible to hydrogen embrittlement. Remedial measures such as avoiding over protection potential, that increase tempering temperature were suggested. Methods to optimize stress distribution of the bolt were also suggested based on FEA calculation. [ABSTRACT FROM AUTHOR]

This paper introduces a high-force-density linear actuator for an artificial heart, which is based on the concept of a magnetic screw–nut. The novelty of the proposed magnetic screw is adaptation of Halbach permanent-magnet (PM) array disposed helically. PMs are placed on both the screw and the nut. The configuration of the newly designed magnetic screws is presented, and its electromagnetic performances are analyzed. The proposed Halbach magnetized magnetic screw is evaluated as compared with a radially magnetized magnetic screw using the time-stepping finite-element method, verifying the advantages of the proposed structure. [ABSTRACT FROM AUTHOR]

Graph classification has drawn great interests in recent years due to the increasing number of applications involving objects with complex structure relationships. To date, all existing graph classification algorithms assume, explicitly or implicitly, that misclassifying instances in different classes incurs an equal amount of cost (or risk), which is often not the case in real-life applications (where misclassifying a certain class of samples, such as diseased patients, is subject to more expensive costs than others). Although cost-sensitive learning has been extensively studied, all methods are based on data with instance-feature representation. Graphs, however, do not have features available for learning and the feature space of graph data is likely infinite and needs to be carefully explored in order to favor classes with a higher cost. In this paper, we propose, CogBoost, a fast cost-sensitive graph classification algorithm, which aims to minimize the misclassification costs (instead of the errors) and achieve fast learning speed for large scale graph data sets. To minimize the misclassification costs, CogBoost iteratively selects the most discriminative subgraph by considering costs of different classes, and then solves a linear programming problem in each iteration by using Bayes decision rule based optimal loss function. In addition, a cutting plane algorithm is derived to speed up the solving of linear programs for fast learning on large scale data sets. Experiments and comparisons on real-world large graph data sets demonstrate the effectiveness and the efficiency of our algorithm. [ABSTRACT FROM PUBLISHER]

Highly loaded and large span timber beams are often used for halls, public buildings or bridges. Reinforcement of beams may be required to extend the life of the structure, due to deterioration or damage to the material/product or change of use. The paper summarises methods to repair or enhance the structural performance of timber beams. The main materials/products cross sections and geometries used for timber beam are presented. Furthermore, their general failure modes are described and typical retrofitting and reinforcement techniques are given. The techniques include wood to wood replacements, use of mechanical fasteners and additional strengthening materials/products. [ABSTRACT FROM AUTHOR]

This paper assesses the performance of a newly developed blind bolt, intended for use in constructing bolted moment-resisting connections to concrete-filled tubular steel profiles. A total of ten connection tests are reported, with each configuration having been subjected to a predominantly tensile force in a representation of the tension region of a typical moment connection. The test variables included type of fastener, addition of concrete to the tube, strength of the concrete, spacing among bolts, and bolt class. On the basis of deformability response, the benefits of filling the tubular member with concrete are highlighted. The favorable performance that results from using a relatively, high-grade concrete infill is also highlighted. The addition of a concrete infill to the tube stiffens and strengthens the otherwise relatively flexible tube walls, enhancing overall connection behavior in terms of stiffness, strength, and ductility. The performance of connections to concrete-filled tubular steel profiles using blind bolts with headed anchors is shown to be suitable for moment-resisting construction. [ABSTRACT FROM AUTHOR]

This paper presents results from tests aimed to assess the relative ductility of titanium alloy Ti 6Al-4V and stainless steel A286 aerospace fasteners of comparable size and tensile strength. A test procedure is developed, and tensile tests are performed on test fasteners. All test fasteners fracture in the threaded region. Elastic and plastic deformation at rupture are extracted from the resulting load versus displacement curves and used to compute the ductility index for each test fastener. The ductility index quantifies the relative ductility between the different fastener materials. The average ductility index for the titanium alloy fasteners is about one-tenth the average value for the A286 fasteners. In addition, the fracture surfaces of the titanium alloy test fasteners fracture perpendicular to the axis of tensile loading, whereas the A286 test fasteners fracture across three or four threads, which corresponds to about a 45° angle. Both the relative ductility index values and fracture surface characteristics indicate much less ductility in the titanium alloy fasteners. These results are not intended to discourage the use of titanium alloy fasteners but rather to provide additional data for use in proper joint design when the benefits of lower weight or extreme temperature use are required. [ABSTRACT FROM AUTHOR]

This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both seated and unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48 h cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present and to analyze the capabilities of a process named “springback-forming”, dedicated to stiffened panels such as airplane׳s fuselage panels. The principle of this forming process is to apply a tension on the stiffener, before the assembly stage with the sheet in a flat configuration using fasteners, adhesives, or a welding process, etc., the bending of the structure is then achieved by springback energy of the stiffener when its tension is released. Using an analytical and finite element models, we studied the capabilities of this process in terms of curvature limits in the case of a single-curved stiffened panel. The results of both models are in good agreement. Through a parametric study, numerical simulations show that when the structure is relatively slender the curvature radius obtained is uniform. Moreover, the value of this radius is independent of the structure׳s length and is mainly limited by the stiffener׳s height. The carried out experimental tests, using laser beam welding as a joining process, demonstrated the feasibility of the process. From the proposed modeling, it is possible to evaluate the range of achievable curvature radius and its uniformity for different values of both geometrical and mechanical parameters of the structure. [ABSTRACT FROM AUTHOR]

This paper presents a novel microgripper mechanism for micromanipulation and assembly. The microgripper is driven by a piezoelectric actuator, and a three-stage flexure-based amplification has been designed to achieve large jaw displacements. The kinematic, static and dynamic models of the microgripper have been established and optimized considering the crucial parameters that determine the characteristics of the microgripper. Finite element analysis was conducted to evaluate the characteristics of the microgripper, and wire electro discharge machining technique was utilized to fabricate the monolithic structure of the microgripper mechanism. Experimental tests were carried out to investigate the performance of the microgripper and the results show that the microgripper can grasp microobjects with the maximum jaw motion stroke of 190 μm corresponding to the 100-V applied voltage. It has an amplification ratio of 22.8 and working mode frequency of 953 Hz. [ABSTRACT FROM PUBLISHER]

Active learning has gained a high amount of attention due to its ability to label a vast amount of unlabeled collected earth observation (EO) data. In this paper, we propose a novel active learning algorithm which is mainly based on employing a low-rank classifier as the training model and introducing a visualization support data point selection, namely, first certain wrong labeled (FCWL). The training model is composed of the logistic regression loss function and the trace-norm of learning parameters as regularizer. FCWL selects those data points whose labels are predicted wrong but the classifier is highly certain about them. Our experimental results performed on different extracted features from a dataset of SAR images confirm at least 10% improvement over the state-of-the-art methods. [ABSTRACT FROM PUBLISHER]

This paper presents a feasibility study of the application of giant magneto resistive (GMR) sensors in detecting motion of slow moving fluids. A motivating application for the proposed effort is the development of a smart catheter capable of monitoring the amount of body fluid drained from the ventricles of the brain. Microfabricated ferromagnetic flaps are used to detect motion of the surrounding fluid. The deflection of the flaps is detected by an ultrasensitive GMR sensor placed outside of the lumen of the catheter. Numerical and experimental results are provided demonstrating a resolution of 1.4 mL/h. Numerical analysis of the fluid past the sensing element show an optimal hinge length of the flexible flaps, as well as a significant increase in sensitivity with reduction of the by-pass gap to $\sim 50~\mu $ m. The effect of electro-magnetic interference and other sources of low-frequency noise (drift) has also been investigated. The results from the study are used to derive a set of design rules that may lead to the successful development of a smart catheter. [2014-0148] [ABSTRACT FROM AUTHOR]

The clinical practice of spine navigation has rapidly grown with the development of image-based guidance. In this paper, a brief history of spinal navigation is presented and a review of clinical outcomes for 12 \thinspace 622 pedicle screws placed using the latest technology in the sacral, lumbar and thoracic regions. The clinical evidence demonstrate that intraoperative 3D image guided surgery has a 96.8% success rate. A concluding section detailing existing barriers that limit more widespread adoption and future development efforts is presented. [ABSTRACT FROM AUTHOR]

This paper introduces a new type of linear actuator using the electromagnetic attractive force, which enables a submillimeter stroke. In general, actuation by the electromagnetic attractive force causes a tradeoff problem between the thrust force and the stroke because the thrust force depends on the gap between the electromagnet and the armature; an increase in the gap (stroke) drastically degrades the thrust force. To realize a submillimeter stroke while retaining a high thrust force, a structure that adopts a displacement amplification mechanism is proposed, which is often used to expand the stroke of a piezoelectric actuator. First, the electromagnetic attractive force is theoretically examined with and without displacement amplification. We verify that displacement amplification could create a higher thrust force and energy efficiency over a certain displacement. On the basis of this examination, a prototype actuator is designed, and the driving principle is illustrated. Further, an analytical model of the proposed actuator is developed for control and performance estimation. Several fundamental experiments with a developed actuator are performed in order to reveal the potential of the proposed actuator. The performance evaluations show that the maximum stroke is approximately 450 $\mu$m and a bandwidth greater than 300 Hz can be realized, and more a time constant is approximately 2 ms for a stroke of 450 $\mu$m. In addition, the experimental results were compared with the simulation results calculated from the analytical model to verify whether the prototype drives predictably according to the proposed concept under a dynamic situation. These results demonstrate that the proposed actuator enables good actuation performance, and it implies that there are tremendous advantages from the viewpoints of manufacturing, assembly, control, etc. [ABSTRACT FROM PUBLISHER]

Applicability of currently available approaches to predict the fatigue life of riveted joints in aircraft structures is limited to cases when the actual joint, for which the predictions are made, and the reference joint, for which the prediction model has been tuned, differ only in the geometry. It is required that the riveting process should be similar for the actual and reference case, but the similarity criterion cannot be formulated in a precise way. In the prediction model developed by the authors and presented in this paper the influence of riveting on the fatigue life of a joint is unambiguously characterized by measurable quantities, namely rivet hole expansion and the load transfer distribution. Hence, the similarity of the riveting processes for the reference and actual joint is no longer required, which considerably extends the transferability of the reference results. A validation of the model is performed by comparing fatigue lives computed and observed in over 80 fatigue tests on aluminium alloy, lap joint specimens with three rivet rows, typical for aircraft fuselage skin connections in the longitudinal direction. Various combinations of production variables, such as sheet material and thickness, the squeeze stress and rivet type, were involved. A significant improvement in the present model prediction accuracy compared to a model which disregards the effect of riveting has been noted. Specifically, underestimates or overestimates of the fatigue life observed for the latter model in the case when hole expansion of the actual joint is larger or smaller respectively than for the reference joint are avoided with the present approach. [ABSTRACT FROM AUTHOR]

In this paper, a real-time railway fastener detection system using a high-speed laser range finder camera is presented. First, an extensive analysis of various methods based on pixel-wise and histogram similarities are conducted on a specific railway route. Then, a fusing stage is introduced which combines least correlated approaches also considering the performance upgrade after fusing. Then, the resulting method is tested on a larger database collected from a different railway route. After observing repeated successes, the method is implemented on NI LabVIEW and run real-time with a high-speed 3-D camera placed under a railway carriage designed for railway quality inspection. [ABSTRACT FROM PUBLISHER]

This paper presents a literature review of the state-of-the-art experimental and analytical methodologies adopted in the construction industry for the design of mechanically fastened connections and joints in pultruded fibre reinforced polymer framed structures. Results and conclusions obtained from the published literature relating to the effects of critical parameters, which include geometry, material properties, configuration, connecting components, fasteners, lateral restraint, etc. on the mechanical behaviour and failure modes are discussed in the light of addressing gaps in knowledge that need resolving to prepare design guidance that is reliable and robust. Further research required to improve the design of composite mechanically fastened joints is identified as a result of this review. [ABSTRACT FROM AUTHOR]

Soft actuators comprised of fluidic structures with fiber-reinforced elastomeric enclosures are seen throughout nature, exhibiting strength, power density, resilience, and diverse motions and forces. However, these structures are rarely used by engineers, in part due to the absence of a generalized understanding of their kinematics and forces. A small subset of soft actuators generating only extension or compression, popularly known as McKibben actuators, has been thoroughly investigated. This paper introduces the entire design space of actuators built with two families of fibers, of which McKibben actuators occupy a subset. The helix angle of the actuator's translation and rotation deformation is determined from the kinematics of the fiber deformation for all fiber angles as the actuator is pressurized. The volumetric transduction of the actuators, relating the output motion to change in contained volume, is analytically determined. The results are discretized to provide a designer with an easy to use design selection chart. The kinematics, force, and moment of the actuators are experimentally validated for all fiber angles. [ABSTRACT FROM PUBLISHER]

This paper aims to study the mechanical behaviour and failure mode of Al 2024-T3 in double-lap bolted joints. To accomplish this, the effect of geometric parameters was investigated in both configurations of single and double fasteners. Using ABAQUS/Standard, a three-dimensional finite element model was developed and verified against the experimental results of the joints loaded in tension. In general, double bolt joints were found to have greater load carrying capacities than single bolt joints (by 40%-49%). In single bolt joints, the plate width had insignificant effect on the behaviour of the joint under tensile loading; whereas, increasing the distance of the hole from the edge, considerably enhanced the strength of the joint. In double bolt joints, changing the edge distance had almost no effect on the behaviour of the joint. However, increasing the plate width from 25.4 to 30 mm increased the load carrying capacity by 28%. This study showed that in single bolt connections, with increasing the edge distance, the failure mode can favourably shift from shear-out to bearing. Also, double bolt joints with wider plates (increased width) can beneficially shift the failure mode from net-tension to bearing. The geometric parameters were found to play an important role in controlling the failure mode so that catastrophic failure modes of net-tension and shear-out can be prevented in bolted joint. [ABSTRACT FROM AUTHOR]

In this paper, a dielectric barrier discharge cylindrical reactor has been analyzed in order to increase the efficiency of nitrogen oxide (NOx )removal from the simulated gas under the room temperature. The effects of electrode shape as well as electrode diameter and electrode length are investigated in the nonthermal plasma reactor. Two different electrode configurations (rod and screw thread electrodes) are examined. The experimental result shows that for the rod electrode, NOx removal efficiency is enhanced by increasing the electrode diameter. However, the screw thread electrode is more effective in decreasing NOx concentration. Finally, the results showed that the average input power requirement for NOx removal can be reduced almost 14% using a 1-mm screw thread electrode instead of a rod electrode. [ABSTRACT FROM PUBLISHER]

In this paper, a tilting-type balancing mobile robot platform is investigated for enhancing lateral stability. In addition to pitch, yaw, and straight motion by the conventional two-wheeled inverted pendulum mechanism, it can generate roll and vertical motion by an additional tilting mechanism. The static force analysis shows that body separation tilting is more advantageous in power consumption than single body tilting, specifically when the payload to body weight is relatively small. Some design considerations are given for the determination of body structure and actuator powers. For the dynamic modeling, the titling balancing platform is assumed as a three-dimensional inverted pendulum with moving base and the nonlinear equation of motion is derived in terms of Kane's method. Then, a velocity/posture control loop is constructed, where the tilt angle reference is naturally generated according to the centrifugal force variation in following a circular path. Experimental results are given to validate the proposed mobile platform with the tilting control strategy. [ABSTRACT FROM PUBLISHER]

At the level crossings it is possible to find the problems with the corrosion of the parts of the fastening system. These problems are especially at the rubber level crossings and in the tunnels. As a part of the thesis the problem of the corrosion of the tension clamp Skl14 of the producer Vossloh at the rubber level crossings is examined. For the purposes of the comparison the tension clamps without the corrosion protection and the tension clamps with the corrosion protection KTL were examined. As a first step the corrosion features of the tension clamps Skl14 were solved. The examination was divided into two parts. First part it was the examination according to CSN EN ISO 9227. The samples of the tension clamps were putted into the corrosion chamber. After 1728 h the results of the corrosion impacts were not satisfied. It was decided for the second step of the examination. It was the immersion in an electrolyte solution. As a result of the paper the corrosion features of the tension clamps without the corrosion protection and with the corrosion protection are compared. [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]

Efficient and accurate segmentation of cellular structures in microscopic data is an essential task in medical imaging. Many state-of-the-art approaches to image segmentation use structured models whose parameters must be carefully chosen for optimal performance. A popular choice is to learn them using a large-margin framework and more specifically structured support vector machines (SSVM). Although SSVMs are appealing, they suffer from certain limitations. First, they are restricted in practice to linear kernels because the more powerful nonlinear kernels cause the learning to become prohibitively expensive. Second, they require iteratively finding the most violated constraints, which is often intractable for the loopy graphical models used in image segmentation. This requires approximation that can lead to reduced quality of learning. In this paper, we propose three novel techniques to overcome these limitations. We first introduce a method to “kernelize” the features so that a linear SSVM framework can leverage the power of nonlinear kernels without incurring much additional computational cost. Moreover, we employ a working set of constraints to increase the reliability of approximate subgradient methods and introduce a new way to select a suitable step size at each iteration. We demonstrate the strength of our approach on both 2-D and 3-D electron microscopic (EM) image data and show consistent performance improvement over state-of-the-art approaches. [ABSTRACT FROM AUTHOR]

Reinforced concrete construction and steel construction are two of the most common contemporary construction methods. Both methods make use of composite decks as floor systems and diaphragms. During the design of composite decks, the interaction between the steel deck and concrete slab is typically disregarded when calculating the strength of the composite diaphragm due to lack of complete shear transfer, as existing practices such as stamping are not effective to provide substantial composite action. This conservative assumption essentially results in non-efficient use of material. This paper presents a method for ensuring shear transfer through the use of conventional sheet metal screws, driven through the corrugated steel deck and embedded in the fresh concrete. This method is proposed for use in the field between formed steel beams. Both experimental and analytical studies support an increase in strength with the addition of embedded fasteners. Further, experimental results indicate an additional increase in strength with the addition of synthetic reinforcing fibers. The increase in strength with the addition of the fasteners is on the order of 100%. When fasteners are already in use, the addition of synthetic reinforcing fibers can increase strength on the order of 10%. The ultimate deflection of enhanced deck is comparable to deck tested without fasteners, but the initial stiffness of enhanced deck is much higher. [ABSTRACT FROM AUTHOR]

This paper highlights various types of pre-existing parts in SolidWorks and CATIA referring to rl/e possibility of creating new customized parts or blocks. These parts were intended to help those who work in this field and increase the efficiency of designing. For example, they are used in assemblies with bolts, screws, nuts and washers modeled in SolidWorks and CATIA. These software use special tools to add rapidly fasteners to the available holes features in assemblies. The work also presents the possibility of accessing existing parts libraries created by the users or specialized companies and posted on the Internet. In order to illustrate this activity with standardized components, flexible couplings are used. [ABSTRACT FROM AUTHOR]

Ball-screw-driven stages are widely used in industry for long-range and high-precision fabrication. One of the main difficulties in dealing with high-precision motion control is the nonlinear friction, which originates at elastic deformation of the mechanical components. In this paper, first, a novel mechanical model of a ball-screw-driven stage is proposed to analyze the elastic deformation dynamics under various motion conditions. It is achieved that the mechanical deformation characteristic of fast motions differs from the case of slow motions in the zero-speed region, and therefore, performing friction compensation should take the motion conditions into account. Then, based on this observation, a sinc-function-based friction compensation method for slow motions including both reverse motions and nonreverse motions and a Sigmoid-function-based friction compensation method for fast reverse motions are proposed to improve the control performance. Thanks to the very few parameters, the proposed methods can save much trouble in design and maintenance and are particularly suitable for control purposes. Finally, the advantages of the proposed methods are evaluated by experiments. [ABSTRACT FROM PUBLISHER]

This paper describes the results of a continuing study into a new class of multi-site damage problems, viz: the interaction between intergranular cracks and cracks that grow from small naturally occurring material discontinuities at a fastener hole, and extends the findings of the prior investigation by considering the effect of contact between opposing faces of the intergranular cracks. This study suggests that, for the particular problem analysed, the level of contact between the opposing surfaces of the intergranular cracks has little effect on crack growth and that intergranular cracks have little effect, i.e. less than approximately 11%, on crack growth. [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]

In this paper, the influence of modeling the fastening with solid railpads on the vertical dynamics of railway tracks with monoblock sleepers is investigated. A 3D finite element (FE) model is presented with four different fastening representations: (1) commonly used spring-damper pair, (2) area covering spring-damper pairs, (3) solid railpad connected to the rail, and (4) solid railpad in frictional contact with the rail and fixed to the support by preloaded springs, which represent the clamps. The response of the four models to hammer excitation is simulated in the time domain, and the calculated response is transformed into the frequency domain to analyze how the models capture the seven main characteristics of tracks with monoblock sleepers. The numerical results show that the model with solid railpads and clamps reproduce the seven characteristics at a maximum frequency difference of 6%, while the conventional model with spring-damper pairs reaches only a 27%. In the improvement of the fit from multiple spring-damper railpad models to solid railpad models, the two key aspects identified are the Poisson׳s effect and the damping of the ballast. Additionally, the railpad type investigated showed a frequency-independent behavior, at least with acceptable error. In view of the close fit, the models with solid railpads can be used for track and fastening design and to derive track parameters to, for instance, study the deterioration of tracks. [ABSTRACT FROM AUTHOR]

This paper presents an alternative decomposition of spatial stiffness matrices based on the concept of compliant axes. According to the congruence transformation of spatial stiffness, the coordinate-invariant aspects, which are referred to as the central principal components of the $6\times 6$ symmetric positive semidefinite matrices, can be derived uniquely. The proposed decomposition is free from the eigenvalue problems of the $6\times 6$ stiffness matrices so that both Plücker's ray and axis coordinates can be utilized to characterize the elastic system's force–deflection behavior. Hence, an arbitrary spatial stiffness matrix can be uniquely decomposed into two sets of orthogonal spring wrenches with finite and infinite pitches, respectively. The decomposed wrenches with finite pitches correspond to the stiffness’ wrench-compliant axes, along which linear deformations produce only wrenches parallel to them. As a result, three torsional and three screw springs are required, at the most, to realize a given spatial stiffness. Using the principal axes decomposition, some physical appreciations, such as the center of stiffness, the wrench-compliant axes, and the correspondence of compliance and stiffness, can be derived to reveal the inherent structure of spatial stiffness in an intuitive manner. In order to verify the effectiveness of the proposed method, two numerical examples are intensively studied with comparison to the eigenscrew decomposition. In addition, a potential application of the proposed stiffness decomposition method is also provided for the structural compliance modeling of flexible links in robot manipulators. [ABSTRACT FROM PUBLISHER]

In this paper an exhaustive singularity analysis of a 3RRR planar parallel robot is performed. The Jacobian matrix using the Screw theory is obtained and an effective method for singular configurations analysis based on a condition index of the Jacobian matrix is presented. Finally, a new similarity law that allows the workspace optimization free of singular configurations and the working mode selection is presented. Furthermore, MATLAB as a testing tool and programming language is used. [ABSTRACT FROM PUBLISHER]

This paper proposes a parallel structure of a feedback controller for the ball–screw drive systems which have significant dynamic variations during operations. The controller consists of two controllers with two different objectives. One controller aims at moving the workpiece table so that its position tracks reference trajectories with high speed and high accuracy. The other controller is for suppressing the structural vibration caused by the cutting force disturbance around system’s resonant frequencies. To take into account the resonant modes’ variations which are peculiar to ball–screw drives, a gain-scheduled controller is utilized as the vibration suppression controller. Advantages of the proposed controller structure in the ball–screw drive control application are discussed. It is experimentally demonstrated that the controller with the parallel structure is effective in achieving high performance in both trajectory tracking and cutting force disturbance rejection. [ABSTRACT FROM PUBLISHER]