Pin Array Research Articles

J1103-1-5 マイクロアクチュエータ・アレイによる触覚ディスプレイ([1103-1]次世代アクチュエータシステム)

In order to investigate effects on presentation tactile-haptic reality, the authors developed a multi-modal display capable of simulating mechanoreceptors of fingers in addition to the muscle-tendons. The multi-modal display was constituted of a manipulator having three-degrees of freedom. The tactile display has a display pad of a 12-by-4 array of stimulus pins, which generates distributed pressure on a human operator's finger surface. Since this tactile display has relative large display pad, an operator can touch an object with three fingers by natural way. Vertical movement of virtual tactile pad in the virtual world is controlled by compressed forced applied on the display pad. The compressive force is measured by a strain load cell installed under the actuator array. The tactile pad simulated in the virtual world is moved in the vertical direction in proportion to the compression force. In order to evaluate this display, we are developing to puzzle game software, in which an operator manipulates 9 pieces block to arrange them to a specific configuration. We will verify presentation ability of this display according to efficiency of the manipulation.

Identification of the optimum resolution specification for a haptic graphic display

This research seeks to identify the most appropriate resolution for a haptic graphic display based on a pin array utilising active feedback. Initially, fourteen participants from varied social and educational backgrounds participated in a repeated measures experiment to compare the recognition of six simple patterns using three different resolutions. The results demonstrated that a significantly higher proportion of shapes could be identified using the second of the three resolutions when compared with the lowest, but that there was no statistically significant difference between the two higher resolutions. These results led to a second hypothesis: that there was an optimum resolution at which shapes could be identified and that increasing the resolution above this point would not increase the likelihood of recognition. There was, however, the possibility that interference between the pins on the highest resolution may have been affecting the participants’ ability to identify shapes at this resolution, so a second experiment was conducted using a resolution slightly lower than the highest. The results demonstrated that the initial findings were correct and supported the hypothesis that there is an optimum resolution that allows the greatest number of shapes to be determined without any significant benefit from increasing the resolution.

Pressure Loss and Heat Transfer Through Heat Sinks Produced by Selective Laser Melting

Heat removal from electronic packages is often assisted with the use of heat sinks whose heat transfer surfaces come in a variety of forms such as cylindrical pins, flat fins, and corrugated sheet. These conventional designs are manufactured by traditional methods such as forging, machining, casting, stamping and bending, or a combination of processes. This article introduces a novel manufacturing technique, selective laser melting (SLM), and demonstrates its ability to fabricate new designs of heat sink that have not previously been considered, primarily due to their geometric complexity. Three novel finned structures have been manufactured and their thermal and fluid flow characteristics have been determined experimentally. The three heat sinks demonstrate selective laser melting's ability to produce fine detail and consist of a staggered elliptical array, an elliptical array where the pins are angled in a direction perpendicular to the flow, and a densely packed diamond array. The novel heat sink designs were compared to a cylindrical pin array manufactured using the SLM process as well as with pin fin data from the literature. The heat sinks produced by the SLM method have been shown to have superior performance to that of the conventional heat sinks. Although the angled elliptical fins transmit similar amounts of heat to the cylindrical pin fins across the range of air flow rates considered, they incur a lower pressure loss. The densely packed diamond array not only transfers 60% more heat than the cylindrical array, but does so with a lower pressure drop across it.

Low Incidence of Postoperative Complications Due to Pin Placement in Computer-Navigated Total Knee Arthroplasty

Computer-navigated joint arthroplasty surgery using optical tracking systems requires arrays fixated to bone via pins. Reports of fractures at pin sites have raised concern about safety. We reviewed the postoperative complications occurring in a single-surgeon series of 984 consecutive primary total knee arthroplasties. All pins were placed unicortically and connected by a dual pin array. Femoral pins were placed into the medial epicondyle, and tibial pins were placed in the shaft 10 cm inferior to the joint line. There were no fractures. Seventeen (1.7%) patients had minor pin-related complications. Twelve patients had a superficial infection around the tibial pin sites, which resolved with antibiotics. None of the infections required readmission or reoperation. We believe pin placement to be safe and effective with proper technique.

Pinning, thermally activated depinning and their importance for tuning the nanoprecipitate size and density in high J c YBa 2Cu 3O 7−x films

YBa 2Cu 3O 7− x (Y123) films with quantitatively controlled artificial nanoprecipitate pinning centers were grown by pulsed laser deposition (PLD) and characterized by transport over wide temperature ( T) and magnetic field ( H) ranges and by transmission electron microscopy (TEM). The critical current density J c was found to be determined by the interplay of strong vortex pinning and thermally activated depinning (TAD), which together produced a non-monotonic dependence of J c on c-axis pin spacing d c . At low T and H, J c increased with decreasing d c , reaching the very high J c ∼ 48 MA/cm 2 ∼20% of the depairing current density J d at 10 K, self-field and d c ∼ 10 nm, but at higher T and H when TAD effects become significant, J c was optimized at larger d c because longer vortex segments confined between nanoprecipitates are less prone to thermal fluctuations. We conclude that precipitates should extend at least several coherence lengths along vortices in order to produce irreversibility fields H irr (77 K) greater than 7 T and maximum bulk pinning forces F p ,max(77 K) greater than 7–8 GN/m 3 (values appropriate for H parallel to the c-axis). Our results show that there is no universal pin array that optimizes J c at all T and H.

An MT-style optical package for VCSEL and PIN arrays

A compact optical package for mounting a vertical cavity surface emitting laser (VCSEL) or PIN array has been developed. Each package couples an array to a fiber ribbon terminated with a commercial MT ferrule. The package is fabricated with beryllium oxide (BeO), allowing efficient removal of the heat produced by the array. The package is quite compact as it is significantly smaller than an MT ferrule. The design simplifies testing and assembly of an optical link system because each fiber ribbon can be readily connected/disconnected while preserving good light coupling efficiency.

Suppression of dissipation in Nb thin films with triangular antidot arrays by random removal of pinning sites

The depinning current ${I}_{c}$ versus applied magnetic field $B$ close to the transition temperature ${T}_{c}$ of Nb thin films with randomly diluted triangular arrays of antidots is investigated. Our experiments confirm essential features in ${I}_{c}(B)$ as predicted by Reichhardt and Olson Reichhardt [Phys. Rev. B 76, 094512 (2007)]. We show that, by introducing disorder into periodic pinning arrays, ${I}_{c}$ can be enhanced. In particular, for arrays with fixed density ${n}_{p}$ of antidots, an increase in dilution ${P}_{d}$ induces an increase in ${I}_{c}$ and decrease of the flux-flow voltage for $B>{B}_{p}={n}_{p}{\ensuremath{\Phi}}_{0}$.

Radiation-hard/high-speed data transmission using optical links

The silicon trackers of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN (Geneva) use optical links for data transmission. An upgrade of the trackers is planned for the Super LHC (SLHC), an upgrade of LHC with ten times higher luminosity. We investigate the radiation-hardness and bandwidth of various components for possible application in the data transmission upgrade. For the electrical connection between the front-end electronics and the optical link, we study the possible use of a micro twisted-pair cable. The bandwidth is measured to be 640 Mb/s for transmission up to 1.4 m and 320 Mb/s for transmission up to 4 m if the signal is pre-emphasized. For the optical devices, we irradiated Vertical-Cavity Surface-Emitting Laser (VCSEL) and GaAs PIN arrays from three vendors and silicon PIN arrays from one vendor. All arrays can be operated up to the SLHC dosage except for the GaAs PIN arrays, which have very low responsivities after irradiation. We have also demonstrated the feasibility of fabricating a novel optical package for housing VCSEL and PIN arrays with BeO (beryllium oxide) as the substrate for efficient removal of heat.

Transport anisotropy as a probe of the interstitial vortex state in superconductors with artificial pinning arrays

We show using simulations that when interstitial vortices are present in superconductors with periodic pinning arrays, the transport in two perpendicular directions can be anisotropic. The degree of the anisotropy varies as a function of field due to the fact that the interstitial vortex lattice has distinct orderings at different matching fields. The anisotropy is most pronounced at the matching fields but persists at incommensurate fields, and it is most prominent for triangular, honeycomb, and kagome pinning arrays. Square pinning arrays can also show anisotropic transport at certain fields in spite of the fact that the perpendicular directions of the square pinning array are identical. We show that the anisotropy results from distinct vortex dynamical states and that although the critical depinning force may be lower in one direction, the vortex velocity above depinning may also be lower in the same direction for ranges of external drives where both directions are depinned. For honeycomb and kagome pinning arrays, the anisotropy can show multiple reversals as a function of field. We argue that when the pinning sites can be multiply occupied such that no interstitial vortices are present, the anisotropy is strongly reduced or absent.

Creating Usable Pin Array Tactons for Nonvisual Information.

Spatial information can be difficult to present to a visually impaired computer user. In this paper, we examine a new kind of tactile cuing for nonvisual interaction as a potential solution, building on earlier work on vibrotactile Tactons. However, unlike vibrotactile Tactons, we use a pin array to stimulate the finger tip. Here, we describe how to design static and dynamic Tactons by defining their basic components. We then present user tests examining how easy it is to distinguish between different forms of pin array Tactons demonstrating accurate Tacton sets to represent directions. These experiments demonstrate usable patterns for static, wave, and blinking pin array Tacton sets for guiding a user in one of eight directions. A study is then described that shows the benefits of structuring Tactons to convey information through multiple parameters of the signal. By using multiple independent parameters for a Tacton, this study demonstrates that participants perceive more information through a single Tacton. Two applications using these Tactons are then presented: a maze exploration application and an electric circuit exploration application designed for use by and tested with visually impaired users.

Heat Transfer and Pressure Drop Measurements in Constant and Converging Section Pin and Diamond Pedestal Arrays

High solidity pin and pedestal arrays are beneficial in reducing temperature gradients and distributing stress across double wall cooling channels such as trailing edge regions. In this study two high solidity (45%) cooling channel geometries were selected and tested in both constant channel height and converging channel configurations. One geometry consisted of a high solidity round pin fin array and the other geometry consisted of a rounded diamond pedestal array designed to minimize pressure drop. Heat transfer rates for both geometries were determined on a row by row basis for both the constant channel and converging channel configurations. Heat transfer and pressure drop measurements were acquired in a bench scale test rig. Reynolds numbers ranged from approximately 3000 to 60,000 for the constant channel arrays and 3500 to 100,000 for the converging arrays based on the characteristic dimension of the pin or pedestal and the local maximum average velocity across a row. The high solidity pin fin array had an axial spacing (X/D) of 1.043 and a cross channel spacing (Z/D) of 1.674. The high solidity diamond pedestal array had an axial spacing of 1.00 and a cross channel spacing of 1.93. The constant section pin fin array had a channel height to diameter of 0.95 while the constant section diamond pedestal array had a height to characteristic dimension of 0.96. The converging pin fin array had an inlet to exit convergence ratio of 2.87 over five heated rows while the converging pedestal array had an inlet to exit convergence ratio of 3.53 over seven heated rows. The constant channel height internal cooling schemes have shown that the high solidity pin fin and the rounded diamond pedestal arrays produce comparable heat transfer and array pressure drop. Both the converging channel arrays show a noticeable (5–7%) reduction in heat transfer compared with the constant height channels. Array pressure drop for the two converging geometries was found to be quite consistent.

Platonic crystals: Bloch bands, neutrality and defects

We consider the properties of flexural waves in a periodically-constrained thin elastic plate. A square array of rigid pins is embedded into the plate. We show that such a system supports a stop band commencing at zero frequency, and we evaluate analytically the frequency limits of its first three bands. We show that each band has neutral directions, in which its dispersion relation and group velocity coincide with those of two corresponding plane waves. We construct the stop band Green’s functions and analyse strongly localized defect modes, and we also find the frequency of the resonant defect mode lying in the first band gap.

Mechanical tissue optical clearing devices: evaluation of enhanced light penetration in skin using optical coherence tomography

We report results of a study to evaluate effectiveness of a mechanical tissue optical clearing device (TOCD) using optical coherence tomography (OCT). The TOCD uses a pin array and vacuum pressure source to compress localized regions of the skin surface. OCT images (850 and 1310 nm) of in vivo human skin indicate application of the TOCD provides an up to threefold increased light penetration depth at spatial positions correlated with pin indentations. Increased contrast of the epidermal-dermal junction in OCT images spatially correlates with indented zones. OCT M-scans recorded while applying the TOCD indicate optical penetration depth monotonically increased, with most improvement at early times (5 to 10 s) of TOCD vacuum application. OCT M-scans of ex vivo porcine skin compressed using the TOCD suggest average group refractive index of the tissue increased, corresponding to a decrease in water concentration. Results of our study indicate that mechanical optical clearing of skin may provide an effective and efficient means to deliver increased light fluence to dermal and subdermal regions.

Mechanical tissue optical clearing devices: Enhancement of light penetration in ex vivo porcine skin and adipose tissue

The complex morphological structure of tissue and associated variations in the indices of refraction of components therein, provides a highly scattering medium for visible and near-infrared wavelengths of light. Tissue optical clearing permits delivery of light deeper into tissue, potentially improving the capabilities of various light-based therapeutic techniques, such as adipose tissue removal or reshaping. We report results of a study to evaluate effectiveness of novel mechanical tissue optical clearing devices (TOCD) using white light photography and infrared imaging radiometry (IIR). The TOCD consists of a pin array and vacuum pressure source applied directly to the skin surface. IIR images recorded light absorption and temperature increase of ex vivo porcine skin and adipose during laser irradiation (980 and 1,210 nm) before and after TOCD application. White light photographic images of in vivo human skin demonstrated localized compression and altered visual appearance, indicative of water and blood movement in skin. White light photographic images also showed increased visible light transport through regions of ex vivo porcine skin compressed by TOCD pins. Rate of heating in sub-dermal adipose regions beneath TOCD pins was twofold higher following TOCD application. Results of our study suggest that mechanical optical clearing may provide a means to deliver increased light fluence to dermal and adipose tissues.

Transverse commensurability effect for vortices in periodic pinning arrays

Using computer simulations, we demonstrate a type of commensurability that occurs for vortices moving longitudinally through periodic pinning arrays in the presence of an additional transverse driving force. As a function of vortex density, there is a series of broad maxima in the transverse critical depinning force that do not fall at the matching fields where the number of vortices equals an integer multiple of the number of pinning sites. The commensurability effects are associated with dynamical states in which evenly spaced structures consisting of one or more moving rows of vortices form between rows of pinning sites. Remarkably, the critical transverse depinning force can be more than an order of magnitude larger than the longitudinal depinning force.

The Biflavonoid Isoginkgetin Is a General Inhibitor of Pre-mRNA Splicing

Membrane-permeable compounds that reversibly inhibit a particular step in gene expression are highly useful tools for cell biological and biochemical/structural studies. In comparison with other gene expression steps where multiple small molecule effectors are available, very few compounds have been described that act as general inhibitors of pre-mRNA splicing. Here we report construction and validation of a set of mammalian cell lines suitable for the identification of small molecule inhibitors of pre-mRNA splicing. Using these cell lines, we identified the natural product isoginkgetin as a general inhibitor of both the major and minor spliceosomes. Isoginkgetin inhibits splicing both in vivo and in vitro at similar micromolar concentrations. It appears to do so by preventing stable recruitment of the U4/U5/U6 tri-small nuclear ribonucleoprotein, resulting in accumulation of the prespliceosomal A complex. Like two other recently reported general pre-mRNA splicing inhibitors, isoginkgetin has been previously described as an anti-tumor agent. Our results suggest that splicing inhibition is the mechanistic basis of the anti-tumor activity of isoginkgetin. Thus, pre-mRNA splicing inhibitors may represent a novel avenue for development of new anti-cancer agents.

The Augmentation of Internal Blade Tip-Cap Cooling by Arrays of Shaped Pins

Abstract The objective of the present study is to demonstrate a method to provide substantially increased convective heat flux on the internal cooled tip cap of a turbine blade. The new tip-cap augmentation consists of several variations involving the fabrication or placement of arrays of discrete shaped pins on the internal tip-cap surface. Due to the nature of flow in a 180deg turn, the augmentation mechanism and geometry have been designed to accommodate a mixture of impingementlike flow, channel flow, and strong secondary flows. A large-scale model of a sharp 180deg tip turn is used with the liquid crystal thermography method to obtain detailed heat transfer distributions over the internal tip-cap surface. Inlet channel Reynolds numbers range from 200,000 to 450,000 in this study. The inlet and exit passages have aspect ratios of 2:1, while the tip turn divider-to-cap distance maintains nearly the same hydraulic diameter as the passages. Five tip-cap surfaces were tested including a smooth surface, two different heights of aluminum pin arrays, one more closely spaced pin array, and one pin array made of insulating material. Effective heat transfer coefficients based on the original smooth surface area were increased by up to a factor of 2.5. Most of this increase is due to the added surface area of the pin array. However, factoring this surface area effect out shows that the heat transfer coefficient has also been increased by about 20–30%, primarily over the base region of the tip cap itself. This augmentation method resulted in negligible increase in tip turn pressure drop over that of a smooth surface.

Radiation-hard optical link for SLHC

We study the feasibility of fabricating an optical link for the SLHC ATLAS silicon tracker based on the current pixel optical link architecture. The electrical signals between the current pixel modules and the optical modules are transmitted via micro-twisted cables. The optical signals between the optical modules and the data acquisition system are transmitted via radiation-hard/low-bandwidth SIMM fibres fusion spliced to radiation-tolerant/medium-bandwidth GRIN fibres. The link has several nice features. We have measured the bandwidths of the micro-twisted-pair cables to be ∼1 Gb/s and the fusion spliced fibre ribbon to be ∼2 Gb/s. We have irradiated PIN and VCSEL arrays with 24 GeV protons and find the arrays can operate up to the SLHC dosage. We have also demonstrated the feasibility of fabricating a novel opto-pack for housing VCSEL and PIN arrays with BeO as the substrate.

Applying the one-column, many pencil local scanning maskless lithography technology to micro-RP system

This paper introduces an innovative one column, many pencil local scanning maskless lithography technology used in dynamic mask and applies it to rapid prototyping (RP) system. By using this technology in micro RP system, the resolution of the 3-D microstructures can be upgraded remarkably. In addition, some relevant experiments are conducted on this micro rapid prototyping system. In the experiment, light beam is projected onto a digital mirror device (DMD) chip [Hornbeck LJ. Digital light processing: A new MEMS-based display, 4th Sensor Symp, p. 297–304 (1996)], and the image is reflected through a micro mirror. Meanwhile, by making use of zoom lens and pins array mask (PAM), the continuing pixels can be scattered. Moreover, in order to project scattered pixels onto the resin surface, the optical system is exploited. Additionally, by using a micro-stage, it is able to control the micro X-Y movement between the scattered pixels. Furthermore, this paper makes use of the spray coating technology to improve the build up capability of the overhand structures of the traditional deep dip liquid-type RP system. Finally, combining the fore-mentioned technologies, one can produce 3-D prototypes with overhand structures in higher resolution.

Radiation-hard optical link for SLHC

We study the feasibility of fabricating an optical link for the SLHC ATLAS silicon tracker based on the current pixel optical link architecture. The electrical signals between the current pixel modules and the optical modules are transmitted via micro-twisted cables. The optical signals between the optical modules and the data acquisition system are transmitted via rad-hard SIMM fibres spliced to rad-tolerant GRIN fibres. The link has several nice features. We have measured the bandwidths of the micro twisted-pair cables to be ∽ 1 Gb/s and the fusion spliced fibre ribbon to be ∽ 2 Gb/s. We have irradiated PIN and VCSEL arrays with 24 GeV protons and find the arrays survive to the SLHC dosage. We have also demonstrated the feasibility of fabricating a novel opto-pack for housing VCSEL and PIN arrays with BeO as the substrate.