Assembly Configurations Research Articles

Bowl Inversion in an Exo-type Supramolecule in the Solid State.

Bowl inversion is a unique property of buckybowls. The polarity and assembly configuration of buckybowls are reversed after bowl inversion. So far, this unique phenomenon has been studied in solution and on surface, but not in solid state due to spatial constraint. Now a series of exo-type supramolecular assemblies of trithiasumanene and nanographene are investigated. Tuning the electron density of the nanogaphene component was found to directly affect the binding constant of the complex. Reversible bowl inversion in the solid state was then successfully achieved by subjecting the trithiasumanene-nanographene assembly with the weakest binding strength to repeated heating-cooling cycles, which was unambiguously observed by single crystal X-ray diffraction.

Flexural Performance of Built-Up Beams Made with Plantation Wood

In this study, Japanese cedar (Cryptomeria japonica (L. f.) D. Don) harvested from a plantation in Taiwan was used to develop built-up beams using self-tapping screws as metal connectors and resorcinol formaldehyde resin as glue to assemble components based on various assembly configurations. Results showed that adding glue provided flexural rigidity, whereas assembly using self-tapping screws resulted in built-up beams with high ductility but relatively low flexural bearing capacity. Beams used glue exhibited approximately linear behavior, whereas those using only screws exhibited some undulating and stepwise responses, implying that shear force between the flanges and the web may cause buckling as well as the dislocation of the self-tapping screws. When using components of similar grades, adding another web can improve the performance. Furthermore, the grades of flanges can strongly influence the flexural load-bearing capacity. In addition, a smaller spacing between the screws can improve the flexural load-bearing performance, but also cause wooden components to crack. Typical bending failure modes were observed in the developed built-up beams, indicating tension failure of the bottom flange as well as slippage between flanges and the web due to horizontal shear, which also caused buckling deformations in the screws.

Design of Two Experimental Mock-Ups as Proof-of-Concept and Validation Test Rigs for the Enhanced EU DEMO HCPB Blanket

Within the framework of EUROfusion activities, the helium cooled pebble bed (HCPB) breeding blanket is under development in Karlsruhe Institute of Technology (KIT). The enhanced HCPB, using a fissionlike fuel breeder pin assembly configuration, is proposed as the near-term breeding blanket for the European Union DEMOnstration power plant (EU DEMO). The helium gas with a pressure of 8 MPa is used as the coolant, EUROFER is used as the structural material, advanced ceramic breeder pebbles are used as the tritium breeder, and Be12Ti is used as the neutron multiplier material. In contrast to the former HCPB cooling plate configuration, the fuel breeder pin assemblies greatly reduce the pressure drop, reducing the circulating power to the level where state-of-the-art helium turbomachinery can be used. However, because of the reduced coolant velocity in the breeder zone, the heat transfer performance is compromised, especially in the annular channel of the fuel breeder pins. An increased surface roughness is therefore proposed as a heat transfer augmentation technique for the fuel breeder pins. Although heat transfer augmentation using artificial roughness is common, it is relatively novel for small annular gaps with moderate velocity as the ones in the fuel breeder pins. Currently, a dedicated correlation for the small annular rough-wall channel is available to predict the Nu number. This correlation is wished here to be benchmarked and validated experimentally. Therefore, an experimental investigation on a fuel breeder pin mock-up (mock-up 1) is planned. Additionally, based on computational fluid dynamics calculation, unsteady, nonuniform flow patterns were found at the return flow after the jet impingement in the first-wall region. Another upscaled mock-up (mock-up 2) to investigate the nonuniform flow patterns of the return flow in the annular channel of the fuel breeder pin is planned. The dedicated experimental campaigns are foreseen at the Helium Loop Karlsruhe (HELOKA) in KIT as validation and proof-of-concept test rigs for this enhanced pin design. In this paper, the motivation and the preliminary design of these two mock-ups of the enhanced EU DEMO HCPB blanket are shown, together with the plan for the foreseen experiments.

Numerical prediction of flow and heat transfer in an infinite wire-wrapped fuel assembly

Assessment of different Reynolds Averaged Navier Stokes (RANS) based modelling approaches is performed for an infinite wire-wrapped fuel assembly configuration of a Liquid Metal Fast Reactor (LMFR). The geometric fuel assembly dimensions refer to the present MYRRHA design. In total, four turbulence models are considered, i.e. linear k-ω SST, realizable k-ε, k-ω SST cubic and Elliptic Blending model of the Reynolds Stress Model (RSM-EB). For this configuration, a high fidelity reference is available and is used for numerical comparisons. Following best practice guidelines, a thorough mesh sensitivity, as well as a sensitivity analysis on different turbulence models, are performed. Both qualitative and quantitative analysis are presented in terms of velocity, temperature and turbulent kinetic energy profiles. Of all models tested, RSM-EB, along with k-ω SST cubic, provide best performance, especially for the flow and the thermal fields, consistent with their capability of modelling anisotropic effects in turbulent flows characterised by highly three-dimensional cross flow and complex flow channel structures, such as the one studied in this work.

Precision enhancement in source localization using a double-module, three-dimensional acoustic intensity probe

The three-dimensional (3D) acoustic intensity probe is not popularly used for the source localization of acoustic source because of the large error even though the technique has been well known. In particular, the measured direction-of-arrival strongly depends on the frequency, which is a detrimental drawback that hampers the use of this method. Such spectral bias error, due to the discrete positioning and spacing of sensors surrounding the acoustic center, fluctuates in a nearly regular spectral pattern when a 3D acoustic intensity probe configured in a tetrahedral shape is used. In this work, two error compensation methods are tried: The first method is to adopt a double-module configuration, which is formed by the connected assembly of two intensity modules, but with different locations of acoustic centers for a spatial averaging effect. The second one is the 1/3-octave band averaging of the measured intensity spectrum within the effective measurement range. Because two probe modules are attached, they concatenate 1–3 sensors in the overlap position. Four double-module probes different in assembly configuration of involved two single-modules are tested: modules having a same acoustic center but twisted by 60°, inverted modules sharing one microphone and twisted by 60°, symmetric modules having the joint angle of 60° in the sharing edge, symmetric modules to a common face thus sharing three microphones. Measurements are conducted in an anechoic chamber by changing the source positions for 4 azimuth and 3 elevation angles. The results reveal that the maximum mean bias error of about 4° can be obtained by the double-module 3D acoustic intensity method, depending on the module configuration and angular source position. This contrasts to the fluctuating direction-of-arrival within about ±10° error range, which is obtained by each single-module in a concatenated double-module. In particular, when the band averaging technique is applied to the measured data by the probe module composed of the inverted single modules, the maximum bias error can be reduced to less than 1° in both azimuth and elevation angles.

Assembly of Gold Nanorods into Chiral Plasmonic Metamolecules Using DNA Origami Templates.

The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic nanostructures. The high spatial precision of a DNA origami-templated assembly allows controlling the coupling between plasmonic resonances of individual particles and enables tailoring optical properties of the constructed nanostructures. Recently, chiral plasmonic systems attracted a lot of attention due to the strong correlation between the spatial configuration of plasmonic assemblies and their optical responses (e.g., circular dichroism [CD]). In this protocol, we describe the whole workflow for the generation of DNA origami-based chiral assemblies of gold nanorods (AuNRs). The protocol includes a detailed description of the design principles and experimental procedures for the fabrication of DNA origami templates, the synthesis of AuNRs, and the assembly of origami-AuNR structures. In addition, the characterization of structures using transmission electron microscopy (TEM) and CD spectroscopy is included. The described protocol is not limited to chiral configurations and can be adapted for the construction of various plasmonic architectures.

Development of the RAINBOW code to evaluate assembly bowing reactivity coefficients in sodium-cooled fast reactors

A perturbation theory code RAINBOW was developed to evaluate reactivity feedback effects due to assembly bowing in sodium-cooled fast reactors. During startup and nominal operations, bowing of the core assemblies is induced by thermal gradients and the core geometry is distorted. Depending on the design of the core restraint system, the core can be characterized as having a “free flowering” or a “limited free bow” design. In either case, accurately quantifying the reactivity feedback is required to support the licensing basis of the reactor system through limiting transient and severe accident analyses. Within the RAINBOW code, assembly bowing is modeled by shifting axially discretized assembly segments, and the heterogeneous assembly configurations are represented using an unstructured finite element mesh. This unique approach provides a convenient and general form for tracking the material movements within a heterogeneous hexagonal assembly design. Additionally, this methodology eliminates the need to consider numerous intersections of geometrical meshes and the shifting of material boundaries. The forward and adjoint neutron flux distributions that are required for perturbation theory are reconstructed using a combination of core-wide homogeneous-assembly solutions from the VARIANT transport code and the unstructured, heterogeneous single-assembly solutions from the PROTEUS-SN transport code. Code-to-code verification tests of this methodology were performed using two- and three-dimensional core models. The perturbation theory results agreed well with the reference MCNP6 and PROTEUS-SN solutions, which were obtained through direct eigenvalue calculations of the unperturbed and perturbed core states. Finally, by comparing solution metrics, RAINBOW offers a similar degree of accuracy to MCNP6 with a several order of magnitude reduction in computational time and resources.

Serverless OpenHealth at data commons scale-traversing the 20 million patient records of New York's SPARCS dataset in real-time.

In a previous report, we explored the serverless OpenHealth approach to the Web as a Global Compute space. That approach relies on the modern browser full stack, and, in particular, its configuration for application assembly by code injection. The opportunity, and need, to expand this approach has since increased markedly, reflecting a wider adoption of Open Data policies by Public Health Agencies. Here, we describe how the serverless scaling challenge can be achieved by the isomorphic mapping between the remote data layer API and a local (client-side, in-browser) operator. This solution is validated with an accompanying interactive web application (bit.ly/loadsparcs) capable of real-time traversal of New York’s 20 million patient records of the Statewide Planning and Research Cooperative System (SPARCS), and is compared with alternative approaches. The results obtained strengthen the argument that the FAIR reproducibility needed for Population Science applications in the age of P4 Medicine is particularly well served by the Web platform.

Ultrafast data mining of molecular assemblies in multiplexed high-density super-resolution images

Multicolor single-molecule localization super-resolution microscopy has enabled visualization of ultrafine spatial organizations of molecular assemblies within cells. Despite many efforts, current approaches for distinguishing and quantifying such organizations remain limited, especially when these are contained within densely distributed super-resolution data. In theory, higher-order correlation such as the Triple-Correlation function is capable of obtaining the spatial configuration of individual molecular assemblies masked within seemingly discorded dense distributions. However, due to their enormous computational cost such analyses are impractical, even for high-end computers. Here, we developed a fast algorithm for Triple-Correlation analyses of high-content multiplexed super-resolution data. This algorithm computes the probability density of all geometric configurations formed by every triple-wise single-molecule localization from three different channels, circumventing impractical 4D Fourier Transforms of the entire megapixel image. This algorithm achieves 102-folds enhancement in computational speed, allowing for high-throughput Triple-Correlation analyses and robust quantification of molecular complexes in multiplexed super-resolution microscopy.

Design, Processes & Technology Co-design Methodology

Costs, design complexity and manufacturing risks are creating opportunities with a rapid convergence of the traditional IC design and IC package design processes. For the goal of achieving the electrical (SI/PI) performance requirements of a complex SoC design, choices of package technology, impact of material selection, process flow optimization are critical factors with increasing challenges to overcome. We have undertaken a co-design methodology to optimize the IC chip layout and substrate design to streamline assembly processes while assimilating the physical and logical interactions within each design domain. We have optimized the die top-level/RDL layout & pattern, defined bump placement & structures for the current density, established electrical constraints for critical nets, applied PG supply strategy, and facilitated routings in the package thereby mitigating assembly risks. To streamline the design and development process, we have employed simulation tools for a thorough evaluation of electrical, mechanical and thermal performance to identify the areas of enhancing the packaging assembly processes:Cadence XtractIM and Ansys SIwave to assess current density and electrical performance on the combo of die + package.Ansys mechanical to understand the underlying assembly issues such as stress induced to die and bumps.Mentor Graphics Flotherm to evaluate the thermal performance per the different die thickness and bump stackup. Using simulation results as the guideline, we have defined and conducted DOEs focusing on bump structures and stackup, die thickness, substrate stackup, assembly mold processes (CUF vs MUF), die placement and configuration, and low CTE material selection to mitigate underlying assembly issues and refine the assembly recipes. We have gained a thorough understanding of dependency factors on the assembly manufacturing processes and parameters in each DOE to finetune and finalize the assembly PORs for the advanced package technology. The refined assembly recipes have delivered the robust package performance and reliability for high volume production.

Study of the MTF of a MWIR T2SL focal plane array in IDDCA configuration

Type-II InAs/GaSb superlattice (T2SL) has recently matured into a commercially available technology addressing both MWIR and LWIR spectral domains. As the prerequisites such as Quantum Efficiency (QE) and dark current were met, more advanced figures of merits related to the ElectroOptic (EO) system as a whole can now be studied to position this technology. In this paper, we focus on modulation transfer function (MTF) measurements. Knowing the MTF of a detector is indeed of primary importance for the EO system designers, since spatial filtering affects the system range. We realized MTF measurements on a 320 × 256 MWIR T2SL FPA provided by IRnova, using a Continuously Self Imaging Grating (CSIG). The advantage of this experimental configuration is that no high performance projection optics is required thanks to the self-imaging property (known as Talbot effect) to project a pattern with known spatial frequencies on the photodetector. Besides, the pattern being propagation invariant, alignment is easier and the bench does not require exact knowledge of the focal plane distance to operate, opening measurement in Integrated Detector Dewar Cooler Assembly (IDDCA) configuration. Extracted from measurements, the pixel size is 26 µm for a pitch of 30 µm.

Utilization of Regionwise Even-Parity Discontinuity Factor to Reduce Discretization Error of MOC

To reduce angular and spatial discretization error of the method of characteristics with a coarse calculation condition, the regionwise even-parity discontinuity factor (EPDF) for transport calculations is evaluated through an iterative procedure using only the regionwise scalar flux, i.e., without the odd-parity angular flux, the partial current, or the net current at the region boundary. The regionwise EPDF is evaluated in a single-assembly geometry with the reflective boundary condition. The evaluated EPDF is applied to a 2 × 2 colorset assembly and core configurations, and the performance is compared to that of the conventional superhomogenization (SPH) method. The calculation results indicate that (1) no convergence issue is observed during the iteration process to estimate the EPDF, (2) the performance of the regionwise EPDF is better than that of the conventional SPH method, and (3) the normalization of the EPDF is necessary to incorporate different surface scalar flux levels among different types of fuel assemblies.

Functionalized Zinc Porphyrins with Various Peripheral Groups for Interfacial Electron Injection Barrier Control in Organic Light Emitting Diodes.

Here, we use a simple and effective method to accomplish energy level alignment and thus electron injection barrier control in organic light emitting diodes (OLEDs) with a conventional architecture based on a green emissive copolymer. In particular, a series of functionalized zinc porphyrin compounds bearing π-delocalized triazine electron withdrawing spacers for efficient intramolecular electron transfer and different terminal groups such as glycine moieties in their peripheral substitutes are employed as thin interlayers at the emissive layer/Al (cathode) interface to realize efficient electron injection/transport. The effects of spatial (i.e., assembly) configuration, molecular dipole moment and type of peripheral group termination on the optical properties and energy level tuning are investigated by steady-state and time-resolved photoluminescence spectroscopy in F8BT/porphyrin films, by photovoltage measurements in OLED devices and by surface work function measurements in Al electrodes modified with the functionalized zinc porphyrins. The performance of OLEDs is significantly improved upon using the functionalized porphyrin interlayers with the recorded luminance of the devices to reach values 1 order of magnitude higher than that of the reference diode without any electron injection/transport interlayer.

Phase transition induced by localized surface plasmon resonance of nanoparticle assemblies

A numerical model concerning the phase transition and temperature distribution of matrix media around plasmonic nanoparticle assemblies under illumination of monochromatic light is investigated. The critical intensity of incident light for isolated nanosphere, nanodisk, and nanorod to melting the surrounding ice is obtained. For nanospheres and nanodisk dimers, enhancement of photothermal conversion (PTC) is observed. Besides, the phase transition of matrix media is not only influenced by PTC, but also the configuration of nanoparticle assemblies. In particular, we demonstrate that for nanorod dimers arranged end-to-end and side-to-side, the dissipation of light for two nanorods are the same in every polarization angles. The change of polarization angle only influence the overall light-to-heat conversion of the dimer. However, for L geometry nanorod dimer, the dissipation of light are different for the two nanorods. This present a way to manipulate and precisely control of temperature distribution and phase transition in nanoscale by tuning the light polarization angles.

Ferromagnetic resonance of a two-dimensional array of nanomagnets: Effects of surface anisotropy and dipolar interactions

We develop an analytical approach for studying the FMR frequency shift due to dipolar interactions and surface effects in two-dimensional arrays of nanomagnets with (effective) uniaxial anisotropy along the magnetic field. For this we build a general formalism on the basis of perturbation theory that applies to dilute assemblies but which goes beyond the point-dipole approximation as it takes account of the size and shape of the nano-elements, in addition to their separation and spatial arrangement. The contribution to the frequency shift due to the shape and size of the nano-elements has been obtained in terms of their aspect ratio, their separation and the lattice geometry. We have also varied the size of the array itself and compared the results with a semi-analytical model and reached an agreement that improves as the size of the array increases. We find that the red-shift of the ferromagnetic resonance due to dipolar interactions decreases for smaller arrays. Surface effects may induce either a blue-shift or a red-shift of the FMR frequency, depending on the crystal and magnetic properties of the nano-elements themselves. In particular, some configurations of the nano-elements assemblies may lead to a full compensation between surface effects and dipole interactions.

A stylized 3D Advanced High Temperature Reactor (AHTR) benchmark problem

A set of Stylized 3D Advanced High Temperature Reactor (AHTR) benchmark problems in full core and single fuel assembly configurations is developed in this paper. The configurations include the lower support plate, the bottom reflector, the fuel zone (AHTR assemblies), the top reflector, and the upper support plate. The benchmark problems retain the multiple heterogeneities and other important neutronics features such as the detailed geometric and material distributions of the Tristructural-Isotropic (TRISO) fuel and burnable poison particles, the fluoride salt coolant, the graphite moderator, and the reflectors. Monte Carlo results are presented for the benchmark problem in both the uncontrolled and controlled single assembly configurations. These benchmark problems can be used for evaluating the performance of neutronics codes.

Structural analysis for final design of ITER sector In-pit Assembly Tool

The Sector In-pit Assembly Tool is special assembly tools to complete nine of the 40° sector which is sub-assembled in the assembly hall into tokamak machine at in-pit. The function of the Sector In-pit Assembly Tool is to support, and stabilize the sub-assembled 40° sectors during tokamak pit assembly. In order to assess the design and the structural integrity of the Sector In-pit Assembly Tool, the structural analyses have been performed under the load combinations according to load specifications including the SL-1 seismic load. There are thirty assembly configurations for Sector In-pit Assembly Tool. Three representative configurations of the assembly configurations are selected to assess the structural integrity. These configurations would be the worst configuration for the central column which is the main part of the tool. The results of the analyses show that the structural integrity meet the design requirements. This paper provides the result of the design for the Sector In-pit Assembly Tool.

Multi-robot grasp planning for sequential assembly operations

This paper addresses the problem of finding robot configurations to grasp assembly parts during a sequence of collaborative assembly operations. We formulate the search for such configurations as a constraint satisfaction problem (CSP). Collision constraints in an operation and transfer constraints between operations determine the sets of feasible robot configurations. We show that solving the connected constraint graph with off-the-shelf CSP algorithms can quickly become infeasible even for a few sequential assembly operations. We present an algorithm which, through the assumption of feasible regrasps, divides the CSP into independent smaller problems that can be solved exponentially faster. The algorithm then uses local search techniques to improve this solution by removing a gradually increasing number of regrasps from the plan. The algorithm enables the user to stop the planner anytime and use the current best plan if the cost of removing regrasps from the plan exceeds the cost of executing those regrasps. We present simulation experiments to compare our algorithm’s performance to a naive algorithm which directly solves the connected constraint graph. We also present a physical robot system which uses the output of our planner to grasp and bring parts together in assembly configurations.

Smart Photosensitizer: Tumor-Triggered Oncotherapy by Self-Assembly Photodynamic Nanodots.

Clinical photosensitizers suffer from the disadvantages of fast photobleaching and high systemic toxicities because of the off-target photodynamic effects. To address these problems, we report a self-assembled pentalysine-phthalocyanine assembly nanodots (PPAN) fabricated by an amphipathic photosensitizer-peptide conjugate. We triggered the photodynamic therapy effects of photosensitizers by precisely controlling the assembly and disintegration of the nanodots. In physiological aqueous conditions, PPAN exhibited a size-tunable spherical conformation with a highly positive shell of the polypeptides and a hydrophobic core of the π-stacking Pc moieties. The assembly conformation suppressed the fluorescence and the reactive oxygen species generation of the monomeric photosensitizer molecules (mono-Pc) and thus declined the photobleaching and off-target photodynamic effects. However, tumor cells disintegrated PPAN and released the mono-Pc molecules, which exhibited fluorescence for detection and the photodynamic effects for the elimination of the tumor tissues. The molecular dynamics simulations revealed the various assembly configurations of PPAN and illustrated the assembly mechanism. At the cellular level, PPAN exhibited a remarkable phototoxicity to breast cancer cells with the IC50 values in a low nanomolar range. By using the subcutaneous and orthotopic breast cancer animal models, we also demonstrated the excellent antitumor efficacies of PPAN in vivo.

Autonomous assembly with collision avoidance of a fleet of flexible spacecraft based on disturbance observer

This paper presents a distributed control law with disturbance observer for the autonomous assembly of a fleet of flexible spacecraft to construct a large flexible space structure. The fleet of flexible spacecraft is driven to the pre-assembly configuration firstly, and then to the desired assembly configuration. A distributed assembly control law with disturbance observer is proposed by treating the flexible dynamics as disturbances acting on the rigid motion of the flexible spacecraft. Theoretical analysis shows that the control law can actuate the fleet to the desired configuration. Moreover, the collision avoidance between the members is also considered in the process from initial configuration to pre-assembly configuration. Finally, a numerical example is presented to verify the feasibility of proposed mission planning and the effectiveness of control law.