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The output characteristic of an inductive power transfer (IPT) system is highly susceptible to variations in magnetic coupling. In this article, a primary-side X-type compensation topology is proposed to acquire stable output characteristics against a wide range of magnetic coupling without resorting to tight control and coil design. By introducing the concept and derivation principle for the coupling-insensitive compensation topologies, the X-type network is presented to provide self-regulation ability for primary coil current against variable coupling, thereby enabling steady power transfer in a highly dynamic environment. The design considerations for the passive parameters are elaborated, followed by the comparison with regular compensation methods. Owing to its unique structure and design flexibility, the X-type compensation exhibits a stable output characteristic that is beneficial in enhancing the tolerance to position shifts. Moreover, it also features a wide soft-switching range and more flexible design for the output level range than previous topologies. Experimental results show stable power transfer over a coupling factor of 0.14–0.28, where the power fluctuation is less than 20%. The presented method is seen as a potential solution for low power IPT systems, where high mobility is demanded.

To ensure the precise relative position between two adjacent parts, multiple pins (10, or even more) are usually set on the parts for positioning. In this case, whether the two adjacent parts can be assembled, and the consequent positioning error is unknown, which might cause a failure in the reasonable selection of parts in the assembly stage, and the reasonable design of relevant parameters (such as the diameters of pins and pinholes, and positional tolerances) in the design stage. In this study, considering the positional tolerance of the pinhole as well as the diameter tolerance of the pin and pinhole, the mathematical model of the accuracy of multi-pin positioning was established, and determined by optimization, obtaining the positioning error. The related assembly experiments were conducted. The measurement results were all in the range of mathematical calculation with the measured data, indicating that the proposed method is effective, and it can provide a direct basis for the part selection in the assembly stage, and the tolerance design in the design stage.

Object recognition in the visual cortex of mammals and humans has inspired many computational object recognition models. Hierarchical model and X (HMAX) is a well-known biologically motivated object recognition model with scale and position tolerance and high accuracy. Due to the computational intensive nature, hardware implementation with massive parallel processing is suggested for real-time applications. However, it is important to explore algorithmic trade-offs when mapping an algorithm to are configurable hardware. A direct conversion of the software implementation of an algorithm generally results inefficient hardware resource usage. In this study, the authors propose a novel modification into the HMAX model which makes it suitable for hardware implementation. More precisely, to reduce the number of memory blocks and multipliers of the S2 layer of HMAX produces, they replace the first norm by the second norm, which critically affects the silicon area in an application-specific integrated circuit implementation or the required resources in field-programmable gate array (FPGA). To evaluate the proposed model, they implement a pipelined version of the revised model on a mid-range commercial Xilinx FPGA, i.e. XC6VLX240T platform from a Virtex 6 family of Xilinx using ISE. Compared to the recent hardware implementation of HMAX, the proposed model offers 83% resource degradation in DSP48 slices and 3% in memory blocks.

Purpose In this study we calculate composite dose delivered to the prostate by using the Calypso tracking ‐data‐ stream acquired during patient treatment in our clinic. We evaluate the composite distributions under multiple simulated Calypso tolerance level schemes and then recommend a tolerance level. Materials and methods Seven Calypso‐localized prostate cancer patients treated in our clinic were selected for retrospective analysis. Two different IMRT treatment plans, with prostate PTV margins of 5 and 3 mm respectively, were computed for each patient. A delivered composite dose distribution was computed from Calypso tracking data for each plan. Additionally, we explored the dosimetric implications for “worst case” scenarios by assuming that the prostate position was located at one of the eight extreme corners of a 3 or 5 mm “box.” To characterize plan quality under each of the studied scenarios, we recorded the maximum, mean, and minimum doses and volumetric coverage for prostate, PTV, bladder, and rectum. Results and discussions Calculated composite dose distributions were very similar to the original plan for all patients. The difference in maximum, mean, and minimum doses as well as volumetric coverage for the prostate, PTV, bladder, and rectum were all

The evaluation of contouring error is important for multi-axis CNC machines because the tolerance specifications of manufactured parts are directly affected by contouring error. One of the fundamental quality inspections to verify that a manufactured part meets the expected tolerance is via form error evaluations. However, the existing estimation methods of contouring error are based on the position tolerance requirements. To meet the form tolerance requirements for the parts, this paper focuses on developing a high-accuracy estimation method of contouring error that is not related to a datum (ND-contouring error). In the proposed estimation method, at first, the minimum zone tolerance (MZT) method is used to transform the ideal tool tip path to match the actual one. Subsequently, by comparing the position and orientation between the actual point and the nearest point on the transformed ideal tool path, the ND-contouring error and orientation contouring error of the tool can be estimated, respectively. In addition, the difference between the proposed estimation method and previous evaluation methods is comparatively analyzed. Finally, simulations and experiments are conducted by applying the S-shaped and B-shaped machining trajectories, respectively, and the results all verify the estimation accuracy of the ND-contouring error estimation method. By adoption of compensation based on the ND-contouring error estimation, the contouring error could be significantly reduced, which will improve the quality of parts.

Source data file for the article authored by Matteucci and Zoccolan on the role of temporal continuity in the development of complex cells in rat V1.

With the increase of the working frequency of the array antenna, tolerance design has become increasingly important. The state-of-art tolerance design methods mainly deal with the position tolerance of the discrete elements. However, the geometric errors of the whole array have resulted from two aspects: (1) the position errors of the discrete elements and (2) the form errors of the continuous reflection plate. To optimize the position tolerance and flatness simultaneously, a hybrid tolerance design method is proposed. First, the relation between the performance of the array antenna and hybrid tolerances was determined based on the second order Taylor expansion. Then the expectation and variance of the performance were derived. Finally, the hybrid tolerances were optimized and the performance of the antenna was improved. Simulation results proved the effectiveness and efficiency of the proposed hybrid tolerance design method.

As typical transmission mechanisms, linkage mechanisms are widely applied in mechanical engineering field, and accuracy prediction of them has received much more attentions especially from some high-precision application fields. For a certain linkage mechanism system, external forces will also cause linkage deformations and deterministic oriented-drift of joint clearances, which become additional variation sources besides component tolerances. In order to perform a more accurate prediction of linkage mechanism, a variation analysis method is proposed in this study, in which component tolerances, joint clearances and deformations are considered. With an equivalent method, positional tolerance and joint clearances are taken into the present variation analysis model, and serve as circular tolerances. Based on classical Euler-Bernoulli beam theory, linkage deformations are disposed as equivalent deviations and contribute to assembly deviations. A decomposing method of percentage contribution, which contains different variation sources, is presented as well. A case study of four-bar linkage mechanism is illustrated to validate the accuracy of the present method by corresponding FEA simulation and experimental test. Moreover, a case study of a three-loop mechanism is also analyzed for the accuracy and percentage contribution of different variation sources with the present method.

According to ISO standards, the position tolerance symbol has only explicit definitions and examples of the specification for a derived point from a sphere under classification of a punctiform toleranced feature. For a real point on an integral surface, there are no explicit definitions and examples. Thus there are gaps in definition here causing undefined and irreproducible applications of position specifications into a real point. This paper suggests a new approach for explicitly defining the function-oriented position tolerance for real points, based on the analysis of its physical behaviour. As a result, an enhanced systematic approach for position tolerance is developed, which fills definition gaps.

Unsupervised learning of visual temporal statistics drives postnatal development of position invariance in visual cortex., Unsupervised adaptation to the spatiotemporal statistics of visual experience is a key computational principle that has long been assumed to govern postnatal development of visual cortical tuning, including orientation selectivity of simple cells and position tolerance of complex cells in primary visual cortex (V1). Yet, causal empirical evidence supporting this hypothesis is scant. Here, we show that degrading the temporal continuity of visual experience during early postnatal life leads to a sizable reduction of the number of complex cells and to an impairment of their functional properties while fully sparing the development of simple cells. This causally implicates adaptation to the temporal structure of the visual input in the development of transformation tolerance but not of shape tuning, thus tightly constraining computational models of unsupervised cortical learning.

The welding of the AP1000 Reactor Coolant Pump (RCP) casing and Steam Generator (SG) is an important issue to maintain the integrity of pressure boundary. The position tolerance of pump casing nozzles after welding will directly affect the internal components of the main pump, as well as the on-site assembling processes. This article investigated the method of controlling deformations during welding (such as assembly alignment, groove design, welding process control, etc), in order to prevent excessive welding deformation and therefore extra discrepancies during pump casing positioning. In this paper, we have developed a welding process, which can allow the installations of AP1000 pump casings to meet all nuclear grade requirements.

Geometrical tolerances are defined in the ISO Geometrical Product Specification system that is used worldwide, but on the other hand, the ASME Y14.5 standard is used in American companies to define how far actual parts may be away from their nominal geometry. This paper aimed to investigate whether specifications defining acceptable geometrical deviations in one system can be transformed to specifications in the other system. Twelve selected cases are discussed in the paper. Particularly, two cases of size tolerance, three cases of form tolerances, one case of orientation tolerance, four cases of position tolerance (including position tolerance with MMR for the pattern of five holes) and, finally, two cases of surface profile tolerance (unequally disposed tolerance zone and dynamic profile tolerance). The issue is not only in the several different symbols and a set of different defaults, but also in the different meanings and different application contexts of some symbols that have the same graphical form. The answer to the question raised in the paper title is yes for the majority of indications specified according to ASME Y14.5 when new tools from the 2017 edition of ISO 1101 are applied.

For shafts with a large ratio of length to diameter, the existing measurement method mainly uses a contact coordinate machine. But machining errors have a strong influence on the offline measurement results, and the accumulation errors of the measurement system also make the measurement datum difficult to identify. For this reason, a new on-machine measuring method is proposed based on the spatial analytical geometry theory to achieve the measurement of the shape and position tolerance of shafts. Through the method, the measurement system combines the line laser measuring instrument and the laser displacement sensor together. Then, the ideal central axis of the workpieces can be obtained and serve as a datum. Finally, the on-machine non-contact measurement of large-size shafts with geometric errors is realized with high measurement accuracy (

Currently, CNC machining centers have been designed to provide flexibility for a wide range of applications. They are widely used in the metal cutting industry with many advantages; their accuracy, reliability, repeatability, and productivity are the important factors. Generally, for CNC machining centers, the working area of the machine table is larger than the size of the workpiece. In case of machining small workpieces, the operators can produce several workpieces at the same time by setting several fixtures at different positions on the table. This can reduce setup time for cutting a new set of workpieces. However, the performance of a machine varies throughout the workspace. It is thus possible that two finished parts produced from the different positions of the table will have different values in geometric dimensioning and tolerance (GD&T). Therefore, in this study, the researchers developed a new procedure for establishing the performance map of CNC machines. As a result, the operators are able to know which area can produce workpieces with positional tolerances that do not exceed a given threshold. By using a CNC model DMC 635V DECKEL MAHO together with double ball-bar model Renishaw QC10 ball-bar as a case study, experimental results indicated that this procedure can provide a performance map of the machining centers efficiently.

Tight position tolerance is required for fastener holes in wing manufacturing. Automated drilling system with high positioning accuracy is the key to achieve the requirement. The paper seeks to determine allowable values of variation sources and guarantee the hole position tolerance. The process of reference hole positioning and the compensation of drilling positions are firstly explored and formalized for an automated drilling system integrated with an industrial camera. Based on this, a positioning variation model for automated drilling considering positioning error measurement and compensation is built. After that, positioning variation synthesis being imposed engineering constraints on is mathematically modeled based on the theory of mathematical statistics. In the positioning variation synthesis, imperfect camera installation, nonideal measurement conditions, equipment positioning error, etc. are included. The positioning variation model and involving synthesis strategy have been used to develop an automated drilling system for wing assembly. Experiments conducted on the developed drilling system show that the fastener holes’ desired position tolerance 0.3 mm will not be exceeded, which is a necessary condition of the satisfactory drilling quality of the aircraft wing.

Geometric deviations have huge influences on the functional behavior of product, which should be analyzed and properly controlled. Tolerance analysis, as a way to evaluate geometric deviations, is an essential part of product development. Current Computer Aided Tolerancing systems provide solutions for tolerance analysis but have limitations in the consideration of form deviations. The Skin Model theory, as a new research topic, represents part with non-ideal model that comprises geometric deviations, thus developing into a new computer aided tolerancing approach. In this paper, the related work with respect to the generation of Skin Model Shapes and its application in assembly simulation and tolerance analysis is briefly introduced. In order to overcome its shortcomings in the tolerance analysis employing SMSs, this paper proposes an improved method by taking advantage of the method adopted in a CAT system. The proposed method supports the analysis of position and orientation tolerances and has been proved to be valid through a case study.

Modern markets are becoming increasingly competitive emphasizing the importance of achieving Right First Time (RFT) during the early design stage as a key enabler facilitating cost and time-to-launch (or time-to-market) reduction. One of the leading challenges to deliver RFT is the lack of effective methods to model product errors at early design stage. Usually, the assembly process is designed under the assumption of ideal (nominal) products. On the contrary, it has been demonstrated that product errors (both geometrical and dimensional) affect the performance of the final assembly. To facilitate easy decision making at early design stage, new methods and models are required to support design engineers. In this study, a framework has been proposed for early design support to generate product variation. International standard provides guidelines for product control and inspection (ISO-GPS or ASME-GDT however, the integration of tolerance standard into nominal sized CAD models is not yet achieved. Current, Computer Aided Tolerancing (CAT) tools mainly capable to model orientation and position tolerance specifications, whereas part shape errors are omitted. This paper presents an innovative physics-driven simulation framework to model shape errors of compliant sheet metal parts at early design stage. The modelling framework consists of three important stages: (i) initial shape error prediction using physic-based simulation, such as, stamping process simulation; (ii) individual orthogonal shape error modes/patterns identification based on decomposition techniques, such as, Geometric Modal Analysis (GMA); and, (iii) simulation of shape error variation classes by assigning distribution to each orthogonal shape error modes. The proposed approach enables to generate shape errors at early design stage of assembly process which can be utilized to optimize the assembly process, including fixture design and joining process parameters. An industrial automotive component illustrates the proposed methodology.

In this paper, a local corner smoothing method with consideration of kinematic and real-time constraints (LCS-KRC) is proposed to generate smooth motion trajectory in the vicinity of corners of five-axis linear tool path. Instead of inserting a spline curve at adjacent linear segments, the method directly blends velocities and accelerations of five motion axes and generates C2 cornering trajectories while respecting corner position tolerance and kinematic limits of the drives. The axial and tangential jerk in cornering transition are simultaneously evaluated to avoid excitation of structure vibration. To achieve local corner smoothing, corner feedrate is moderately adjusted and rotary-axis speeds are synchronized with corner velocity profile, especially in reverse motion or at sharp corners. Finally, simulations and experiments results demonstrate effectiveness of the proposed method compared with a commercial controller.

Similar to primates, visual cortex in rodents appears to be organized in two distinct hierarchical streams. However, there is still little known about how visual information is processed along those streams in rodents. In this study, we examined how repetition suppression and position and clutter tolerance of the neuronal representations evolve along the putative ventral visual stream in rats. To address this question, we recorded multiunit spiking activity in primary visual cortex (V1) and the more downstream visual laterointermediate (LI) area of head-restrained Long-Evans rats. We employed a paradigm reminiscent of the continuous carry-over design used in human neuroimaging. In both areas, stimulus repetition attenuated the early phase of the neuronal response to the repeated stimulus, with this response suppression being greater in area LI. Furthermore, stimulus preferences were more similar across positions (position tolerance) in area LI than in V1, even though the absolute responses in both areas were very sensitive to changes in position. In contrast, the neuronal representations in both areas were equally good at tolerating the presence of limited visual clutter, as modeled by the presentation of a single flank stimulus. When probing tolerance of the neuronal representations with stimulus-specific adaptation, we detected no position tolerance in either examined brain area, whereas, on the contrary, we revealed clutter tolerance in both areas. Overall, our data demonstrate similarities and discrepancies in processing of visual information along the ventral visual stream of rodents and primates. Moreover, our results stress caution in using neuronal adaptation to probe tolerance of the neuronal representations. NEW & NOTEWORTHY Rodents are emerging as a popular animal model that complement primates for studying higher level visual functions. Similar to findings in primates, we demonstrate a greater repetition suppression and position tolerance of the neuronal representations in the downstream laterointermediate area of Long-Evans rats compared with primary visual cortex. However, we report no difference in the degree of clutter tolerance between the areas. These findings provide additional evidence for hierarchical processing of visual stimuli in rodents. ispartof: JOURNAL OF NEUROPHYSIOLOGY vol:120 issue:3 pages:926-941 ispartof: location:United States status: published

Verification activity in a streamline manufacturing system is one of the most important activity to make sure that the design requirements and the actual product specifications are met. It helps designer or manufacturing engineer as a feedback by detecting issue at early stage. However, we have to select the most effective verification method that will lead to low cost and relatively fast production. Many industries make machined components that are mounted to welded frame, the locations of the components may float with a larger tolerance to the welded frame than the feature to feature tolerance needed for mounting hole pattern. The composite tolerance is needed for this particular case. The most suitable method for gathering measurement data for small batch production is either automatically using CMM or manually using pin gages and size measurement devices. While, the data processing step can be done by graphic analysis or paper gage method for inspecting composite positional tolerance. The innovation of this journal is changing the way of data processing method by reducing the papers (coordinate grid and polar overlay) required for graphic analysis and converting them into mathematical model that can be processed by computer. Hence, we call this virtual graphic analysis. The benefits of using virtual graphic analysis are reducing cost and time of overall inspection process.

The position error of array antenna significantly deteriorates the gain and sidelobe of the array, which seriously hinders the realization of high performance of communication antenna for Internet of Things (IoT). Based on the sensitivity analysis theory, the sensitivity of the array radiation field with respect to the position of the antenna element is derived. Besides, a novel design method of position tolerance for array antenna is proposed and applied to a 20×20 planar array. Compared with the array designed by traditional method, the gain loss is basically the same (being 0.5 dB), while the peak sidelobe level is lowered by 1.937 dB (φ=0°)/1.586 dB (φ=90°). Besides, the uncertainty analysis results show that the newly designed array has a much higher chance to achieve the desired performance, which fully demonstrates the innovation and effectiveness of the new method.

We embody a miniature reflection-type optical displacement sensor tapping into a projected beam that features high structural tolerance. A code scale with periodic patterns spatially encrypts the projected beam, which is established by imaging a collimated beam from a vertical-cavity surface-emitting laser via an aspheric lens, and linearly expands it, so as to be decoded by a receiver that comprises four serially cascaded identical photodetector cells. For the modulated beam, we observe a pitch increase with a rate of 18 μm/mm along the propagation direction. The two quadrature signals Sig-A and Sig-B derived from the PD signals exhibit a 900 phase relationship. The proposed sensor has been designed via ray-optic simulations and embodied through passive alignment, combined with plastic injection mold. We achieve a positional resolution of 10 μm from either of Sig-A and Sig-B. By concurrently considering the two quadrature outputs, we efficiently enhance the resolution to 2.5 μm, with the discovered direction of displacement. Finally, we thoroughly investigate the crucial dependence of the sensor performance on the positional tolerance pertaining to the constituent elements, which is discovered to be as large as +/-100 μm, under a certain resolution.

This paper presents an integrated hybrid manufacturing approach to enhance and accelerate the adoption of metal Additive Manufacturing (AM) by adding a direct digital subtractive process to the production that is capable of improving the form, location and position tolerance of critical part features as well as improving surface finish. The hybrid system, AIMS (Additive systems Integrated with subtractive MethodS) can be integrated with existing metal AM systems without any significant modifications. The intent of this paper is to: 1) detail the system architecture, 2) highlight the process requirements, and 3) illustrate the sequential functions from development of CAD models through AM processing, to subtractive post-processing and corresponding process monitoring. Attributes of individual components such as physical and computational requirements associated with each discrete step of the overall process is presented. Advantages and current limitations of AIMS are also noted. The developed models provide insight into how the overall process-flow could be affected by errors (variability) due to both physical and data transfer across multiple systems. This paper also presents a generalized use of AIMS-for a variety of part geometries, noting materials and processing efficiencies associated with this unique hybrid method.

Cocuring process is a unique characteristic of composite materials wherein multiple parts like stringers, ribs and spars are simultaneously cured and bonded to a composite skin resulting in an integral structure. It has many benefits like reduction in part count, elimination of stress concentration due to fastener holes in the cocured regions and reduced assembly time and related costs. However, the application of cocuring has been limited on contoured components because of the complexities associated with the tooling. The basic requirements to be fulfilled are (a) consolidation of skins and stiffeners and (b) dimensional tolerance on position and thickness of stiffeners. Proper consolidation can be ensured through the faithful transfer of autoclave pressure by designing tools which are flexible so that they conform to desired shape whereas the positional tolerance can be achieved by using rigid tools. The resolution of such conflicting requirements requires a detailed study of the geometry of the part, design requirements and tolerances achievable on tools. This paper discusses design of tools for two types of cocured structures viz., open and closed cocured structures. The tooling technologies for realising above structures differ considerably. A few tooling concepts have been discussed based on the authors’ experience of developing cocured structures over the last two decades.

We investigate the characteristics of tolerance of metal EBG waveguide, and establish a tolerance analysis model. We get the relation curve of radius tolerance factor, φ, versus the distribution of electric field and the relation curve of position tolerance factor, ψ, versus the distribution of electric field. The double-half-algorithm was firstly proposed, with the admitting criteria, we get φ max with constant ψ, ψ max with constant φ. Meanwhile, the φ max and ψ max can be optimized when φ and ψ varies in the given way. At last, we find the fact that the influence of the first, second, third row metal rods to f and η p descends rapidly. These results will be useful guides for fabrication and performance analyzing of metal EBG devices in the future.

To treat cataract intraocular lenses (IOLs) are used to replace the clouded human eye lens. Due to postoperative healing processes the IOL can displace within the eye, which can lead to deteriorated quality of vision. To test and characterize these effect an IOL can be embedded into a model of the humane eye. One informative measure are wavefront aberrations. In this paper three different setups, the typical double-pass configuration (DP), a single-pass (SP1) where the measured light travels in the same direction as in DP and a single-pass (SP2) with reversed direction, are investigated. All three setups correctly measure the aberrations of the eye, where SP1 is found to be the simplest to set up and align. Because of the lowest complexity it is the proposed method for wavefront measurement in model eyes.

This study proposes a simple method of fabricating flexible electronic devices using a metal template for passive alignment between chip components and an interconnect layer, which enabled efficient alignment with high accuracy. An electrocardiogram (ECG) sensor was fabricated using 20 mu m thick polyimide (PI) film as a flexible substrate to demonstrate the feasibility of the proposed method. The interconnect layer was fabricated by a two-step photolithography process and evaporation. After applying solder paste, the metal template was placed on top of the interconnect layer. The metal template had rectangular holes at the same position as the chip components on the interconnect layer. Rectangular hole sizes were designed to account for alignment tolerance of the chips. Passive alignment was performed by simply inserting the components in the holes of the template, which resulted in accurate alignment with positional tolerance of less than 10 mu m based on the structural design, suggesting that our method can efficiently perform chip mounting with precision. Furthermore, a fabricated flexible ECG sensor was easily attachable to the curved skin surface and able to measure ECG signals from a human subject. These results suggest that the proposed method can be used to fabricate epidermal sensors, which are mounted on the skin to measure various physiological signals.