Pin Locations Research Articles

Assessing risk of damage to posterior ankle structures during total ankle arthroplasty.

AimsArthroplasty has become increasingly popular to treat end-stage ankle arthritis. Iatrogenic posterior neurovascular and tendinous injury have been described from saw cuts. However, it is hypothesized that posterior ankle structures could be damaged by inserting tibial guide pins too deeply and be a potential cause of residual hindfoot pain.MethodsThe preparation steps for ankle arthroplasty were performed using the Infinity total ankle system in five right-sided cadaveric ankles. All tibial guide pins were intentionally inserted past the posterior tibial cortex for assessment. All posterior ankles were subsequently dissected, with the primary endpoint being the presence of direct contact between the structure and pin.ResultsAll pin locations confer a risk of damaging posterior ankle structures, with all posterior ankle structures except the flexor hallucis longus tendon being contacted by at least one pin. Centrally-aligned transcortical pins were more likely to contact posteromedial neurovascular structures.ConclusionThese findings support our hypothesis that tibial guide pins pose a considerable risk of contacting and potentially damaging posterior ankle structures during ankle arthroplasty. This study is the first of its kind to assess this risk in the Infinity total ankle system.Cite this article: Bone Jt Open 2021;2(7):503–508.

An Effective Block Pin Assignment Approach for Block-Level Monolithic 3-D ICs

In a 2-D design, the block pins are located at the periphery of a block optimally since blocks are placed side-by-side horizontally in a single placement layer. However, monolithic 3-D (M3D) integration relieves this boundary constraint by allowing vertical block communication between different tiers based on an nm-scale pitch of 3-D interconnection. In this article, we present a design methodology named pin-in-the-area that assigns block pins at any position inside the boundary of a block using commercial 2-D place-and-route (P&R) tools and enables an efficient block implementation and integration for a block-level M3D integrated chips (ICs). Our pin-in-the-area starts from the netlist restructuring and connectivity-aware tier-by-tier chip planning, which defines blocks and decides their sizes and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(X,Y,Z)$ </tex-math></inline-formula> locations for a two-tier M3D design. Next, we perform wirelength-driven 3-D placement to minimize 3-D half-perimeter wirelength (HPWL) and find optimal pin locations inside the boundary of a block. Once block designs are done, we apply the unique macro handling scheme to the top-level timing closure. Based on a 28-nm two-tier M3D hierarchical design result, we show that our solution offers 13.6% and 24.7% energy-delay-product reduction compared to the M3D design with pins assigned at the block boundaries and its 2-D counterpart, respectively.

Quantitative imaging and automated fuel pin identification for passive gamma emission tomography

Compliance of member States to the Treaty on the Non-Proliferation of Nuclear Weapons is monitored through nuclear safeguards. The Passive Gamma Emission Tomography (PGET) system is a novel instrument developed within the framework of the International Atomic Energy Agency (IAEA) project JNT 1510, which included the European Commission, Finland, Hungary and Sweden. The PGET is used for the verification of spent nuclear fuel stored in water pools. Advanced image reconstruction techniques are crucial for obtaining high-quality cross-sectional images of the spent-fuel bundle to allow inspectors of the IAEA to monitor nuclear material and promptly identify its diversion. In this work, we have developed a software suite to accurately reconstruct the spent-fuel cross sectional image, automatically identify present fuel rods, and estimate their activity. Unique image reconstruction challenges are posed by the measurement of spent fuel, due to its high activity and the self-attenuation. While the former is mitigated by detector physical collimation, we implemented a linear forward model to model the detector responses to the fuel rods inside the PGET, to account for the latter. The image reconstruction is performed by solving a regularized linear inverse problem using the fast-iterative shrinkage-thresholding algorithm. We have also implemented the traditional filtered back projection (FBP) method based on the inverse Radon transform for comparison and applied both methods to reconstruct images of simulated mockup fuel assemblies. Higher image resolution and fewer reconstruction artifacts were obtained with the inverse-problem approach, with the mean-square-error reduced by 50%, and the structural-similarity improved by 200%. We then used a convolutional neural network (CNN) to automatically identify the bundle type and extract the pin locations from the images; the estimated activity levels finally being compared with the ground truth. The proposed computational methods accurately estimated the activity levels of the present pins, with an associated uncertainty of approximately 5%.

External fixator of the elbow

The placement of an external elbow fixator can be statically carried out as temporary stabilization or as a hinged movement fixator. As a hinged movement fixator a functional follow-up treatment is possible due to control of the joint guidance and reduction of the compromising forces on the osteoligamentous structures. As atemporary stabilization of the elbow, the external fixator is used as adamage control method. As a movement fixator it is used as an additional protection and movement control after complex osteoligamentous interventions and persisting tendency to dislocation of the joint and also as a standalone procedure. In some cases, the procedure is also used in distraction arthrolysis of stiff elbows and as asalvage procedure in patients with relevant comorbidities as part of fracture treatment. Inexperience in relation to the procedure as well as alocal acute infection at the level of the intended pin locations should specifically be mentioned as contraindications. In addition, compliance and patient understanding of the procedure are essential for the success of treatment. Soft tissue preparation for pin placement should be preferred over percutaneous incisions to enable asafe bone exposure. Knowledge of the course of neurovascular structures (particularly the radial nerve) is essential. When placing ahinge, knowledge of the position and detection of the idealized center of rotation is of fundamental importance. The type of postoperative management required essentially depends on the underlying injury. When placing ahinged fixator, the aim is to enable movement as early as possible. Nevertheless, blocking of the hinged fixator may be useful for ashort period of time. Adequate pin care over the duration of the treatment is essential in order to prevent complications. Good functional results have been reported for the treatment of unstable elbows after primary and secondary placement of ahinged external fixator. Good functional scores and improvement in the range of motion were also recorded in the context of an arthrolysis (additive for open arthrolysis or distraction arthrolysis); however, in contrast asignificant number of complications associated with this surgery are likely to emerge. As adefinitive salvage procedure, satisfactory results were obtained in asmall case series of aselected older patient group with relevant comorbidities.

A DAG-Based Algorithm for Obstacle-Aware Topology-Matching On-Track Bus Routing

As clock frequencies increase, topology-matching bus routing is desired to provide an initial routing result which facilitates the following buffer insertion to meet the timing constraints. In this article, we present a complete topology-matching bus routing framework considering nonuniform track configurations. In the framework, a bus clustering technique is proposed to reduce the routing complexity by grouping buses sharing similar pin locations. To perform topology-matching routing in a nonuniform track configuration, we propose a directed acyclic graph-based algorithm to connect a bus in a specific topology. Furthermore, a rip-up and reroute scheme is applied to alleviate the routing congestion. Compared with the state-of-the-art topology-matching bus routers, our proposed algorithm significantly improves the routing quality and reduces the number of spacing violations in comparable runtime.

Mixing in flows past confined microfluidic cylinders: Effects of pin and fluid interface offsetting

Inserting obstacles such as cylindrical pins in a micromixer has the potential to significantly enhance scalar transport and improve species mixing between two co-flowing streams. However, it remains unclear how the mixing efficiency in confined microchannel flows is affected by the positioning of the fluid interface and the cylindrical pin with respect to the wall or to each other. The present work investigates the mixing induced by a single cylindrical pin placed at different gap distances from the wall of a Y-type micromixer. Two fluid interface positions are considered by mixing the fluid streams at different ratios; one located at the channel centreline and one shifted towards one of the walls. Micro particle image velocimetry (μPIV) is applied to investigate the velocity fields and streamline patterns for the different pin locations, and micro laser-induced fluorescence (μLIF) to acquire the instantaneous concentration fields and assess the mixing performance, utilising the intensity of segregation technique. Prior to the onset of vortex-shedding and when the fluid interface coincides with the channel centreline, slightly offsetting the pin from the centreline is found to yield the best mixing performance compared to centreline or near wall pin locations. However, when vortex-shedding is present, a centreline pin location exhibits the best mixing performance. The present measurements indicate that single micropins can enhance mixing, even in the absence of vortex-shedding, and when vortex-shedding occurs, they are most efficient when the pin axis and fluid interface are aligned.

A novel temporary cranial fixation device for awake cranial surgery: Technical report of 14 cases.

Background:Awake craniotomy has become the gold standard in various cranial procedures. As part of the awake technique, three-point pin fixation of the patient’s head is important. One of the issues we encountered is the problem of matching the scalp infiltration site with the final pin position. To overcome this problem, we developed a flat plunger type fixator that adapts to the Mayfield holder.Methods:Our fixator has a 2.5 cm metallic shaft that articulates in a ball and socket joint to allow its concave surfaces to adapt to the patient’s scalp. After placing the patient in the desired position, the head is fixed with the three plungers, circles are drawn around each plunger, and they are then removed for the circles to be infiltrated with bupivacaine. Standard fixation pins are then placed in the Mayfield holder and aimed at the center of the circles.Results:So far, we have operated on 14 patients with this technique. No patient experienced pain during temporary fixation, and the drawn circles ensured that there were no mismatches between the local anesthetic and pin locations. The technique was particularly useful on hairy scalps, where infiltration sites were hidden. We also used only 22.5 mg bupivacaine at the pin sites, freeing a dose for the field block around the scalp incision.Conclusion:The temporary plunger type fixator provided a simple method to economize on local anesthetic use, check the patient’s head position before final fixation, and ensure that the Mayfield pins matched with the anesthetized area.

Flip Chip Underfill RF Characterization

Abstract To develop reliable high-speed packages, characterization of the underfill material used in the flip-chip process has become of greater importance. The underfill, typically an epoxy resin-based material, offers thermal and structural benefits for the integrated circuit (IC) on package. With so many inputs and outputs (IOs) in close proximity to one another, the integrated circuits on package can have unexpected signal and power integrity issues. Furthermore, chip packages can support signals only up to the frequency where noise coupling (e.g., crosstalk, switching noise, etc.) leads to the malfunctioning of the system. Vertical interconnects, such as vias and solder bumps, are major sources of noise coupling. Inserting ground references between every signal net is not practical. For the solder bumps, the noise coupling depends on the permittivity of the underfill material. Therefore, characterizing the permittivity of the underfill material helps in predicting signal and power integrity issues. Such liquid or semi-viscous materials are commonly characterized from a simple fringe capacitance model of an open-ended coaxial probe immersed in the material. The open-ended coaxial method, however, is not as accurate as resonator-based methods. There is a need for a methodology to accurately extract the permittivity of liquid or semi-viscous materials at high frequencies. The proposed method uses solid walled cavity resonators, where the resonator is filled with the underfill material and cured. Dielectric characterization is a complex process, where the physical characteristics of the cavities must be known or accurately measured. This includes the conductivity of the conductors, roughness of the conductors, the dimensions of the cavity, and the port pin locations. This paper discusses some of the challenges that are encountered when characterizing dielectrics with cavity resonators. This characterization methodology can also be used to characterize other materials of interest.

Transverse Vibration of Clamped-Pinned-Free Beam with Mass at Free End

Engineering systems undergoing extreme and harsh environments can often times experience rapid damaging effects. In order to minimize loss of economic investment and human lives, structural health monitoring (SHM) of these high-rate systems is being researched. An experimental testbed has been developed to validate SHM methods in a controllable and repeatable laboratory environment. This study applies the Euler-Bernoulli beam theory to this testbed to develop analytical solutions of the system. The transverse vibration of a clamped-pinned-free beam with a point mass at the free end is discussed in detail. Results are derived for varying pin locations and mass values. Eigenvalue plots of the first five modes are presented along with their respective mode shapes. The theoretical calculations are experimentally validated and discussed.

Wear analysis of pin and roller surfaces

In this paper three different combinations were evaluated: (i) steel pin vs steel roller, (ii) steel pin vs tungsten disulfide (WS2) coated roller and (iii) PVD pin vs steel roller. The aim of this paper is to properly quantify the topographical variations of the pin/roller surfaces and asses the appropriateness of the measuring technique before and after the tribological tests primarily performed for friction reduction. In-house tribometer was used to test the friction/wear performance of the three different combinations. Surface topographies were measured by white light interferometer (3D) and mechanical stylus (2D). To enable fast relocation on the stylus and interferometer, a 3D printed mask was used. Regarding the pins, Sa, Sk and Svk have been found to follow the wear changes: the lowest wear change for the combination (ii) and highest for the combination (i) but less for the combination (iii). Regarding the changes of Ra on the pin locations where edge contact occurs, the largest changes were found to be for combination (i), followed by combination (ii) and (iii). Ra and Rk change less significantly for the roller surfaces. Good correlations among the friction, initial/final roughness and radial displacements were also found.

Finite element analyses of the stability of a soil block reinforced by shear pins

The assessment of slope stability is an essential task in geotechnical engineering. In this paper, a threedimensional (3D) finite element analysis (FEA) was employed to investigate the performance of different shear pin arrangements to increase the stability of a soil block resting on an inclined plane with a low-interface friction plane. In the numerical models, the soil block was modeled by volume elements with linear elastic perfectly plastic material in a drained condition, while the shear pins were modeled by volume elements with linear elastic material. Interface elements were used along the bedding plane (bedding interface element) and around the shear pins (shear pin interface element) to simulate the soil-structure interaction. Bedding interface elements were used to capture the shear sliding of the soil on the low-interface friction plane while shear pin interface elements were used to model the shear bonding of the soil around the pins. A failure analysis was performed by means of the gravity loading method. The results of the 3D FEA with the numerical models were compared to those with the physical models for all cases. The effects of the number of shear pins, the shear pin locations, the different shear pin arrangements, the thickness and the width of the soil block and the associated failure mechanisms were discussed.

SU‐E‐I‐52: Use of Radiochromic Film for the Estimation of CTDI100 and In‐ Phantom Dose Profiling

Purpose: To establish a methodology for the use of radiochromic film in the estimation of CTDI100 and provide an in‐phantom spatial description of the radiation dose profile. Methods: Standard CTDI 32cm body and 16cm head phantoms were used with a modified Acrylic pin to allow for the insertion of radiochromic. Two CT scanners were evaluated at various beam collimations in both center and 12 oˈclock pin locations. For comparison purpose, CTDI 100 measurements were obtained using a 100mm pencil ionization chamber. A 48‐bit optical scanner was used to scan the radiochromic film. Software code was written to analyze the film images. A set of calibration films was acquired on a fluoroscope with similar beam quality (kVp and HVL) as the CT scanner. Results: For reproducibility three films from each of 21 different collimation and pin location combinations were analyzed. Three films were excluded because of prominent moiré patterns observed likely caused by moisture on the film or scanner platform. Three images that were included slightly exceeded the calibration range of the film. The percent differences between the CTDI 100 values obtained with the 100mm pencil chamber and the film ranged from 0– 17.2% with an average difference of 8.6%. The relative standard deviation of the CTDI100 film values ranged between 0.3–3.6% with an average of 1.9%. Though not novel, visual indication of the z axis in phantom beam profile provided very clear evidence that at large collimations radiation dose extends well beyond a 100mm region. Conclusions: Radiochromic film has the potential to estimate CTDI 100 with reasonable accuracy; future calibration methods may bring better accuracy. This method provides additional value by yielding a visual indication of the CT dose profile and potential for easily incorporating dose beyond 100mm.

Macro-Fiber Composite actuated simply supported thin airfoils

A piezoceramic composite actuator known as Macro-Fiber Composite (MFC) is used foractuation in the design of a variable camber airfoil intended for a ducted fan aircraft. Thestudy focuses on response characterization under aerodynamic loads for circular arc airfoilswith variable pinned boundary conditions. A parametric study of fluid–structureinteraction is employed to find pin locations along the chordwise direction that result inhigh lift generation. Wind tunnel experiments are conducted on a 1.0% thick, 127 mm chordMFC actuated bimorph airfoil that is simply supported at 5% and 50% of the chord.Aerodynamic and structural performance results are presented for a flow rate of15 m s − 1 and a Reynolds number of 127 000. Non-linear effects due to aerodynamicand piezoceramic hysteresis are identified and discussed. A lift coefficientchange of 1.46 is observed, purely due to voltage actuation. A maximum 2DL/D ratio of 17.8 is recorded through voltage excitation.

Sensitivity-Based External Calibration of Multiaxial Loading System

Due to the nonlinear nature of coordinate transformations, evaluation and calibration of multiaxial loading systems in global Cartesian coordinates are challenging problems. This study proposes a systematic calibration method for multiaxial loading systems in global coordinates using an external measurement system. Global coordinate measurement for a multiaxial loading system is usually obtained from a geometric transformation based on internal actuator measurements. However, any misrepresentation of initial actuator configuration (e.g., origin, pin locations, etc.) introduces errors and cross-talk in the global Cartesian coordinates. Such errors and cross-talk cannot be observed or eliminated based on internal measurements. The method proposed in this paper is based on the sensitivity of the global coordinates with respect to the initial actuator length. To validate the proposed method, calibration is performed using the state-of-the-art Load and Boundary Condition Box at University of Illinois at Urbana-Champaign as the multiaxial loading system and the Krypton Dynamic Measurement Machine as the external measurement system. Experimental results demonstrate that the proposed sensitivity-based external calibration method is effective for improving control accuracy and reducing cross-talk of multiaxial loading systems in global Cartesian coordinates.

Fast Flip-Chip Pin-Out Designation Respin for Package-Board Codesign

Deep submicrometer effects drive the complication in designing chips, as well as in package designs and communications between package and board. As a result, the iterative interface design has been a time-consuming process. This paper proposes a novel and efficient approach to designating pin-out, which is a package ball chart describing pin locations for flip-chip BGA package when designing chipsets. The proposed approach can not only automate the assignment of more than 200 input/output (I/O) pins on package, but also precisely evaluate package size which accommodates all pins with almost no void pin positions, as good as the one from manual design. Furthermore, the practical experience and techniques in designing such interface has been accounted for, including signal integrity, power delivery and routability. This efficient pin-out designation and package size estimation by pin-block design and floorplanning provides much faster turn around time, thus enormous improvement in meeting design schedule. Our pin-block design contains two major parts. First, we have pin-block construction to locate signal pins within a block along the specific patterns. Six pin patterns are proposed as templates which are automatically generated according to the user-defined constraints. Second, we have pin-blocks grouping to group all pin-blocks into package boundaries. Two alternative pin-blocks grouping strategies are provided for various applications such as chipset and field-programmable gate array (FPGA). The results on two real cases show that our methodology is effective in achieving almost the same dimensions in package size, compared with manual design in weeks, while simultaneously considering critical issues and package size migration in package-board codesign.

EXPERIMENTAL INVESTIGATIONS ON RADIATION CHARACTERISTICS OF IC CHIPS

The proposed work focuses on the experimental investi- gation of radiation characteristics of the discarded IC chips mounted on the dielectric substrate when fed trough one of the metal leg pins. Several sets of the experimental results are obtained using Vector Net- work Analyzer to obtain the return loss characteristics of the proposed structure. The return loss characteristics reveal that at some frequen- cies the ICs certainly show radiation mechanism. Feeding the same chip at different pin locations, changes the resonant frequency. The measured radiation pattern of the IC chip shows an omni-directional characteristic. This experimental study also reveals that the ICs can be easily interfered by the surrounding radiation prevalent in any wireless environment following the reciprocity principle of an antenna.

Techniques for Fast Physical Synthesis

The traditional purpose of physical synthesis is to perform timing closure , i.e., to create a placed design that meets its timing specifications while also satisfying electrical, routability, and signal integrity constraints. In modern design flows, physical synthesis tools hardly ever achieve this goal in their first iteration. The design team must iterate by studying the output of the physical synthesis run, then potentially massage the input, e.g., by changing the floorplan, timing assertions, pin locations, logic structures, etc., in order to hopefully achieve a better solution for the next iteration. The complexity of physical synthesis means that systems can take days to run on designs with multimillions of placeable objects, which severely hurts design productivity. This paper discusses some newer techniques that have been deployed within IBM's physical synthesis tool called PDS that significantly improves throughput. In particular, we focus on some of the biggest contributors to runtime, placement, legalization, buffering, and electric correction, and present techniques that generate significant turnaround time improvements

Radiation Efficient Unidirectional Low-Profile Slot Antenna Elements for X-Band Application

Abstract. Slots in metallic ground planes are very promising candidates for conformal antenna applications. However, a low-profile unidirectional antenna requires a back reflector close to the slot and the resulting stripline feed causes strong excitation of parallel-plate modes. In this contribution, we consider unidirectional reflector-backed slot configurations with parallel-plate mode suppression by shorting pins. Starting from a parametric study with respect to shorting pin location and back reflector distance, we present a stripline-fed rectangular slot element with radiation efficiency of more than 80% and a bandwidth of about 5% at centre frequency 10GHz. A careful optimisation of shorting pin locations guarantees reliable parallel-plate mode suppression without deteriorating the slot radiation behaviour. Coupling coefficients between parallel and aligned rectangular slot elements are presented. For increased bandwidth applications, a bow-tie slot element with about 8% bandwidth and radiation efficiency of close to 80% is proposed.

Pin design for part feeding

Industrial parts can be fed (oriented) using a sequence of fixed horizontal pins to topple the parts as they move past on a conveyor belt. We give an algorithm for designing a sequence of such pins for a given part. Given the n-sided convex polygonal projection of a part, its center of mass and frictional coefficients, our O(n2) algorithm computes the toppling graph, a new data structure that explicitly represents the mechanics of toppling, rolling, and jamming. We verify the toppling graph analysis with experiments. Our O(n3n) design algorithm uses the toppling graph to design a sequence of pin locations that will cause the part to emerge in a unique orientation or to determine that no such sequence exists.

Partitioning algorithms for layout synthesis from register-transfer netlists

A partitioning methodology that exploits the regularity of register-transfer components is presented, and partitioning algorithms that are used to generate the floor plan are described. The partitioning algorithms not only select the layout style best suited for each component, but also consider critical paths, I/O pin locations, and connections between components. This approach improves the overall area utilization and minimizes the wire length on the critical paths.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>