Open Geometry Research Articles

Determination of the effect of the open cell foam material geometry on the value of energy efficiency

THE PURPOSE. Improving the energy efficiency of open cell foam materials with different geometries (SC, BCC, FCC, DEM) and with different medium porosities (ε=0.7; ε=0.75; ε=0.8; ε=0.85; ε=0.9; ε=0.95) by numerical simulation. To determine the influence of the geometry and porosity of an open cell foam material on the values of pressure drop, heat flux and energy efficiency factor.METHODS .Numerical simulation was carried out using the ANSYS Fluent 19.2 software package. Geometric models of porous structures are sets of intersecting spheres with different packing structures: periodic Simple Cubic packing (SC), Face Centered Cubic packing (FCC), Body Centered Cubic packing (BCC), and random structure generated by the discrete element method (DEM).The calculations were carried out at the following air flow velocities: 0.01; 0.05; 0.25; 0.5; 0.75; 1; 1.25 m/s.RESULTS. Atair flow velocities of 0.01 m/s and 0.05 m/s, all the studied structures show approximately the same heat flux. With porosity values ε=0.75; ε=0.8; ε=0.85 the highest values of heat flow were shown by the FCC structure, with porosity ε=0.7; ε=0.9; ε=0.95 the BCC structure had the highest heat flux. This is explained by the fact that, at the corresponding porosity values, the FCC or BCC structure had the largest surface area, which provided the largest heat flux. With the porosities of media ε=0.7 and ε=0.75, the BCC and FCC cell packages show a high pressure drop. With the porosities of media ε=0.8 and ε=0.85, the highest pressure drop corresponds to FCC cell packing, and for porosities ε=0.9 and ε=0.95, to BCC cell packing.CONCLUSION. With equal high porosity, the BCC cell packing provides a higher value of heat flux than the FCC structure. The SC package has the lowest heat flux values for all studied porosities. The SC package also has the lowest pressure drop values and therefore the highest energy efficiency values.

FEA Investigation of Elastic Buckling for Functionally Graded Material (FGM) Thin Plates with Different Hole Shapes under Uniaxial Loading

In this paper, an investigation of linear eigenvalue buckling of functionally graded material (FGM) plates under uniaxial loading is carried out. The computer model is analyzed using the finite element (FE) package ABAQUS. An analysis is carried out to study the effect of the size and geometry of openings in the FGM plate on the critical buckling load. The circular, square, and diamond openings vary in size based on the ratio of the opening diameter to the width of the FGM plate. Moreover, the effect of the aspect ratio (width to thickness) of the FGM plate on the critical buckling load is examined. Further, the effect of the power law index on buckling behavior is investigated. The results show that the increase in the size of the opening and the aspect ratio reduces the critical buckling load of the FGM plate. Moreover, the lower the power law index, the higher the critical buckling load. The diamond shape opening shows the best performance in terms of the critical buckling load, and the effect of the plate thickness has a more significant influence on the critical buckling load of the FGM plate compared to the size of the opening.

Investigation of displacement ventilation performance under various room configurations using computational fluid dynamics simulation

The performance of a ventilation system affects air quality, thermal comfort, and energy consumption in indoor environments. To evaluate the performance of displacement ventilation under various room configurations, steady Reynolds Averaged Navier–Stokes (RANS) Computational Fluid Dynamics (CFD) simulations were used. The CFD model was validated using measurements of a full-scale test room. The age of air concept was used to evaluate the ventilation performance regarding indoor air quality. The PD index was used to control the case studies for draft risk. Twelve cases with different configurations were systematically studied and compared with the reference case. The configurations included plan aspect ratio, exhaust opening position, inlet position and geometry, and internal heat gains. The results showed that the overall ventilation performance of a room is less sensitive to room configurations compared with local ventilation performance around the occupants. However, almost in all cases, the occupants were exposed to better-than-average air quality in most cases. The results also indicated that when internal heat gains are small, displacement ventilation should be used with caution. Practical application: Any HVAC system design is based on assumptions made for ventilation performance. Comprehensive knowledge of the influential factors is critical for an efficient design. Regarding the architecture and interior design, the architects are also involved in the ventilation systems since they have an axial role in decision making for room configuration, including but not limited to room geometry, the position of inlet and outlet air terminals, and heat/pollutant sources. Consequently, the impact of room configuration on ventilation performance is of practical importance in the architecture, engineering, and construction industry.

Two‐Photon Nanomachining of a Micromechanically Enhanced Optical Cavity Sensor on an Optical Fiber Tip

Herein, a two‐photon nanostructuring process that is employed to monolithically integrate dynamic three‐dimensional (3D) micromechanical features into Fabry–Pérot cavity (FPC) sensors on an optical fiber tip is demonstrated. These features represent a breakthrough in the integration and fabrication capabilities of micro optomechanical devices and systems. The demonstrated dynamic optical surface enables directional thin‐film deposition onto obscured areas. The rotation of the dynamically movable mirror to deposit a thin reflective coating onto the inner surfaces of a FPC with curved geometry is leveraged. The reflective coating in conjunction with the dynamically rotatable mirror greatly improves the quality factor of the FPC and enables a new class of highly integrated multipurpose sensor systems. A unique open cavity geometry on an optical fiber tip is used to demonstrate temperature and refractive index sensing with sensitivities of 2045 ± 39 nm/RIU and 366 ± 22 pm °C−1, respectively. A gold reflective coating sputtered onto the inner surfaces of the FPC improves the quality factors of the cavity by more than 800%. This technology presents a path forward for utilizing 3D design freedom in micromechanically enhanced optical systems to facilitate versatile processing and advantageous geometries beyond the current state of the art.

Computer-aided optimal design for flexible cable in aerospace products based on dynamic analogy modeling

Due to large, complex deformations, the accurate design of cables has become a major problem in the manufacturing of aerospace products. The current design method often leads to large products, uncertain centroids, and poor reliability. To solve these problems, a computer-aided optimal design method for flexible cables was proposed based on dynamic analogy modeling. A nonlinear optimization model was established by combining Cosserat theory and the minimum potential energy principle. The total deformation energy was considered as the optimization object, and Euler parameters were used as control variables to describe the cable geometric shape. Considering the length and bending radius requirements, the normalized form of the cable constraints was expressed by the cross-section position and orientation matrix. An efficient method to solve this problem using finite element discretization and the primitive dual interior point method was proposed. A digital wiring module was developed based on an open source geometry kernel system, and a cable geometry test bench was built. To verify our model, a satellite wiring simulation example was implemented using the module, SolidWorks, and the test bench. Our method achieved the optimal design for the cable length and geometric shape. A theoretical and technical foundation for effectively solving the problem of large cable manufacturing errors and realizing the lightweight design of aerospace products was outlined.

3D-printed activated carbon for post-combustion CO2 capture

The applicability of 3D-printed activated carbons for their use to CO 2 capture in post-combustion streams and the influence of activation conditions on CO 2 uptake and CO 2 to N 2 selectivity were studied. For two monoliths with the same open cellular foam geometry but low and high burnoff during activation, a series of fixed-bed breakthrough adsorption experiments under typical post-combustion conditions, in a wide range of temperature (313 and 373 K), and partial pressure of CO 2 up to 120 kPa were carried out. It is shown that the higher burnoff during activation of the 3D printed carbon enhances the adsorption capacity of CO 2 and N 2 due to the increased specific surface area with sorption uptakes that can reach 3.17 mol/kg at 313 K and 120 kPa. Nevertheless, the lower burnoff time on monolith 1 leads to higher selectivity of CO 2 over N 2 , up to 18 against 10 on monolith 2, considering a binary interaction to a mixture of CO 2 /N 2 (15/85 vol%) at 313 K. The single and multicomponent adsorption equilibrium is conveniently described through the dual-site Langmuir isotherm model, while the breakthrough curves simulated using a dynamic fixed-bed adsorption linear driving force model. Working capacities for the 3D printed carbon with lower burnoff time lead to the best results, varying of 0.15–1.1 mol/kg for the regeneration temperature 300–390 K. Finally, consecutive adsorption-desorption experiments show excellent stability and regenerability for both 3D printed activated carbon monoliths and the whole study underpins the high potential of these materials for CO 2 capture in post-combustion streams. • Printed activated carbon monoliths were developed as adsorbents for CO 2 capture. • Thermal treatment affects the selectivity of CO 2 over N 2 on the monoliths. • CO 2 working capacity on the monolith M1 is 17% higher than monolith M2. • 3D-printed monoliths show high stability and regenerability over consecutive cycles. • A mathematical model has been developed for process simulation to CO 2 capture.

Semi-empirical quantum optics for mid-infrared molecular nanophotonics.

Nanoscale infrared (IR) resonators with sub-diffraction limited mode volumes and open geometries have emerged as new platforms for implementing cavity quantum electrodynamics at room temperature. The use of IR nanoantennas and tip nanoprobes to study strong light-matter coupling of molecular vibrations with the vacuum field can be exploited for IR quantum control with nanometer spatial and femtosecond temporal resolution. In order to advance the development of molecule-based quantum nanophotonics in the mid-IR, we propose a generally applicable semi-empirical methodology based on quantum optics to describe light-matter interaction in systems driven by mid-IR femtosecond laser pulses. The theory is shown to reproduce recent experiments on the acceleration of the vibrational relaxation rate in infrared nanostructures. It also provides physical insights on the implementation of coherent phase rotations of the near-field using broadband nanotips. We then apply the quantum framework to develop general tip-design rules for the experimental manipulation of vibrational strong coupling and Fano interference effects in open infrared resonators. We finally propose the possibility of transferring the natural anharmonicity of molecular vibrational levels to the resonator near-field in the weak coupling regime to implement intensity-dependent phase shifts of the coupled system response with strong pulses and develop a vibrational chirping model to understand the effect. The semi-empirical quantum theory is equivalent to first-principles techniques based on Maxwell's equations, but its lower computational cost suggests its use as a rapid design tool for the development of strongly coupled infrared nanophotonic hardware for applications ranging from quantum control of materials to quantum information processing.

Burst and oxidation behavior of Cr-coated Zirlo during simulated LOCA testing

Cr-coated Zr-alloys are a near-term cladding concept to improve reactor safety during accident scenarios. Burst and steam oxidation behavior of bare and Cr-coated Zirlo claddings were examined under simulated loss-of-coolant accident conditions. The 4.4 µm coating had no substantial effect on ballooning or opening geometry but did increase burst temperatures at higher pressures. The coating reduced steam oxidation of the cladding compared to bare specimens, but in regions of high strain, the coating developed through-cracks allowing rapid underlying zirconia formation.

Integration of RFID tag in additive manufactured parts

This paper discusses the integration of on-metal tags in additively manufactured Ti-6Al-4V geometries. The manufactured components are to be equipped with information and read out due to aircraft maintenance work. Due to the complex installation and the mostly insufficient accessibility of the component in the installed state in the aircraft, a high read range and readability is mandatory. The integration involves ultra-high-frequency tags, which should promise a long range. The readability of the tags was therefore investigated in different open geometries. Here, some of the integrated tags were readable. In addition, tags were completely embedded in order to understand the effects in the component. The focus here was on the effects in the embedding chamber of the tag. Therefore, the fully embedded tags were cut open and examined. Some tags were readable, others were destroyed during the process. This was due, among other things, to the very hot environment of the process, as this depends highly on the actual permitted operating temperature of the tags. In addition, powder residues and adhesions were noted. These aspects are crucial for subsequent research involving the integration of tags.

Construction of Single-Crystalline Hierarchical ZSM-5 with Open Nanoarchitectures via Anisotropic-Kinetics Transformation for the Methanol-to-Hydrocarbons Reaction.

We report an anisotropic-kinetics transformation strategy to prepare single-crystalline aluminosilicate MFI zeolites (ZSM-5) with highly open nanoarchitectures and hierarchical porosities. The methodology relies on the cooperative effect of in situ etching and recrystallization on the evolution of pure-silica MFI zeolite (silicalite-1) nanotemplates under hydrothermal conditions. The strategy enables a controllable preparation of ZSM-5 nanostructures with diverse open geometries by tuning the relative rate difference between etching and recrystallization processes. Meanwhile, it can also be extended to synthesize other heteroatom-substituted MFI zeolite nanocages. Compared with conventional ZSM-5 microcrystals, nanocrystals, and nanoboxes, the ZSM-5 nanocages with single-crystalline nature, highly open nanoarchitectures, and hierarchical porosities exhibit remarkably enhanced catalytic lifetime and low coking rate in the methanol-to-hydrocarbons (MTH) reaction.

Construction of Single‐Crystalline Hierarchical ZSM‐5 with Open Nanoarchitectures via Anisotropic‐Kinetics Transformation for the Methanol‐to‐Hydrocarbons Reaction

AbstractWe report an anisotropic‐kinetics transformation strategy to prepare single‐crystalline aluminosilicate MFI zeolites (ZSM‐5) with highly open nanoarchitectures and hierarchical porosities. The methodology relies on the cooperative effect of in situ etching and recrystallization on the evolution of pure‐silica MFI zeolite (silicalite‐1) nanotemplates under hydrothermal conditions. The strategy enables a controllable preparation of ZSM‐5 nanostructures with diverse open geometries by tuning the relative rate difference between etching and recrystallization processes. Meanwhile, it can also be extended to synthesize other heteroatom‐substituted MFI zeolite nanocages. Compared with conventional ZSM‐5 microcrystals, nanocrystals, and nanoboxes, the ZSM‐5 nanocages with single‐crystalline nature, highly open nanoarchitectures, and hierarchical porosities exhibit remarkably enhanced catalytic lifetime and low coking rate in the methanol‐to‐hydrocarbons (MTH) reaction.

Optimal thermal design of anisotropic plates with arbitrary cutouts using genetic algorithm

Anisotropic plates in different applications may have geometric defects such as openings and cracks. The presence of the opening disturbs the heat flow, which creates significant thermal stress around the opening. When the heat flux is high enough, these extreme stresses can lead to structural failure. This article aims to obtain the optimal parameters for achieving the minimum value of the normalized stress near the cutout's boundary in perforated anisotropic plates utilizing the genetic algorithm. Optimization parameters include the curvature of opening's corners, orientation angle of opening, fibers angle, heat flux angle, and opening's elongation. The plate is under heat flux, and the opening's border is thermally insulated. The stress distribution around the opening is calculated using Lekhnitskii's complex variable method and complex potential functions. The genetic algorithm is then implemented to find the optimal values for design parameters. The results show that by selecting the optimal parameters related to the anisotropic material and the opening's geometry, the stress intensity factor of the perforated anisotropic plates is remarkably reduced. Furthermore, this optimization algorithm can be extended to find the optimized parameters and achieve the optimal designs in anisotropic and isotropic perforated plates under thermal loadings.

Effect of opening geometries on fire development in a ro-ro space

ABSTRACT A series of model scale experiments were conducted to study the fire development in a ro-ro deck with various opening geometries. The experiments were performed in a 1/8 reduced scale model with a heptane pool fire as fire source. Experimental results show that both the ventilation factor and the opening position affect the fire development. The critical opening ratio for the fire to self-extinguish is 4%, with the opening locating at the bottom of the side walls while no self-extinction is found for other tests. A higher opening position and a larger opening height provide better flow exchange between the deck and the ambient, but this effect is only obvious for 4% opening. Numerical study shows that Fire Dynamic Simulator used with default simple settings underestimates the fire development and yields an early extinction when fire self-extinction occurs. For freely developed fire with large openings, FDS gives more close results to experiments.

Torque Effects of the Stator Slot Opening Geometry Error in Production of Axial Flux PM Motors

Axial flux permanent magnet machines (AFPM) became popular due to their effective profile. But AFPM machines have hard processes on production. Thus, some errors happen at the slot opening area and these errors affect the torque production. So, torque ripples occur. This paper shows the slot opening errors’ effect on the torque. An analytical model has been used to demonstrate the problem. Also, random slot opening width taken randomly with the ten per cent constraint. Results show that slot opening errors have impacts on the torque ripples.

A numerical methodology for monitoring stress distributions and experimental proof of the concept on metal embedded thin polymer-matrix composites using X-ray Diffraction

In this study, a numerical methodology is developed to monitor stress distributions and an experimental technique is investigated to measure stresses on metal embedded polymer matrix fiber-reinforced composite materials using X-ray diffraction (XRD) method. The numerical method successfully predicts the stress distributions using only a few data points with an average accuracies of 11.6% and 11.8%, respectively for tapered and open hole tensile sample geometries. Experimental part of this study investigates different methodologies to measure stresses on surfaces of polymer composites materials of thin walled structures by XRD. For this reason, metallic materials were integrated onto the surface and near-surface of polymer matrix composites in three different configurations as in the forms of metal foil, metal powder, and metal wire mesh. In-situ experiments of measured and applied stresses revealed metal powder embedded composite materials as a promising material configuration for reliable monitoring of stresses.

Reassessing Depositional Conditions of the Pre-Apulian Zone Based on Synsedimentary Deformation Structures during Upper Paleocene to Lower Miocene Carbonate Sedimentation, from Paxoi and Anti-Paxoi Islands, Northwestern End of Greece

The studied area is situated in northwestern Greece and corresponds to the northern end of the Pre-Apulian Zone, in contact with the Apulian platform to the west and the Ionian Basin to the east. The proposed model is based on fieldwork, measured deformation structures, and age determination of the studied deposits. Until now, the known Pre-Apulian platform or Pre-Apulian zone represents the margins of the Apulian platform to the Ionian Basin and was formed due to the normal faults’ activity during the Mesozoic to Cenozoic Eras. Soft sediment deformation (SSD) structures are widespread within the upper Paleocene to lower Miocene limestones/marly limestones that are exposed in both Paxoi and Anti-Paxoi Islands, mostly along their eastern coasts, across sections of 2–3 km long and up to 60 m high. SSD structures, with a vertical thickness up to 10 m, have been observed in limestones and were formed during or immediately after deposition, during the first stage of sediment consolidation. SSD structures are cross-cut by normal faults, indicating their development during the rift stage. There are at least five different SSD horizons, and most of them present either an eastward or a westward progradation. These SSD structures are classified into four (4) different types of deformations: (1) thick synclines and anticlines, formed due to strong synsedimentary deformation; (2) strong and thick SSD structures that produced erosional contacts both with the underlying and the overlying undeformed horizons; (3) thin slumps, having sharp contacts with the underlying undeformed horizons and erosional contacts with the overlying undeformed horizons; and (4) thin slump horizons passing laterally to undeformed deposits in the same horizon. The studied SSD structures and their age of development introduce active margins between the Apulian platform and the Ionian Basin that have been influenced by normal fault activity. These normal faults have been active since the Ionian Basin changed gradually to a foreland basin, and after the tectonic regime changed from extension to compression, during the early to middle Eocene. It seems that compression in the studied Apulian platform margins arrived later and after the lower Miocene, and after the development of the SSD structures. The confinement of the lower Miocene deposits, both northwards and southwards (in Anti-Paxoi Island), indicates the presence of active transfer faults, with flower structure geometry, that were formed during sedimentation, producing highs and troughs. The present open anticline geometry of Paxoi Island indicates that the Island represents the forebulge area of the middle Miocene Ionian Foreland due to Ionian Thrust activity.

Kinetic simulations of collision-less plasmas in open magnetic geometries *

Laboratory plasmas in open magnetic geometries can be found in many different applications such as (a) scrape-of-layer (SOL) and divertor regions in toroidal confinement fusion devices, (b) linear divertor simulators, (c) plasma-based thrusters and (d) magnetic mirrors etc. A common feature of these plasma systems is the need to resolve, in addition to velocity space, at least one physical dimension (e.g. along flux lines) to capture the relevant physics. In general, this requires a kinetic treatment. Fully kinetic particle-in-cell (PIC) simulations can be applied but at the expense of large computational effort. A common way to resolve this is to use a hybrid approach: kinetic ions and fluid electrons. In the present work, the development of a hybrid PIC computational tool suitable for open magnetic geometries is described which includes (a) the effect of non-uniform magnetic fields, (b) finite fully-absorbing boundaries for the particles and (c) volumetric particle sources. Analytical expressions for the momentum transport in the paraxial limit are presented with their underlying assumptions and are used to validate the results from the PIC simulations. A general method is described to construct discrete particle distribution functions in a state of mirror-equilibrium. This method is used to obtain the initial state for the PIC simulation. Collisionless simulations in a mirror geometry are performed. The results show that the effect of magnetic compression is correctly described and momentum is conserved. The self-consistent electric field is calculated and is shown to modify the ion velocity distribution function in a manner consistent with analytic theory. Based on this analysis, the ion distribution function is understood in terms of a loss-cone distribution and an isotropic Maxwell-Boltzmann distribution driven by a volumetric plasma source. Finally, the inclusion of a Monte Carlo based Fokker-Planck collision operator is discussed in the context of future work.

Electron microscopy analysis of ATP-independent nucleosome unfolding by FACT

FACT is a histone chaperone that participates in nucleosome removal and reassembly during transcription and replication. We used electron microscopy to study FACT, FACT:Nhp6 and FACT:Nhp6:nucleosome complexes, and found that all complexes adopt broad ranges of configurations, indicating high flexibility. We found unexpectedly that the DNA binding protein Nhp6 also binds to the C-terminal tails of FACT subunits, inducing more open geometries of FACT even in the absence of nucleosomes. Nhp6 therefore supports nucleosome unfolding by altering both the structure of FACT and the properties of nucleosomes. Complexes formed with FACT, Nhp6, and nucleosomes also produced a broad range of structures, revealing a large number of potential intermediates along a proposed unfolding pathway. The data suggest that Nhp6 has multiple roles before and during nucleosome unfolding by FACT, and that the process proceeds through a series of energetically similar intermediate structures, ultimately leading to an extensively unfolded form.

Atrial fibrillation driver identification through regional mutual information networks: a modeling perspective

PurposeEffective identification of electrical drivers within remodeled tissue is a key for improving ablation treatment for atrial fibrillation. We have developed a mutual information, graph-based approach to identify and propose fault tolerance metric of local efficiency as a distinguishing feature of rotational activation and remodeled atrial tissue.MethodsVoltage data were extracted from atrial tissue simulations (2D Karma, 3D physiological, and the Multiscale Cardiac Simulation Framework (MSCSF)) using multi-spline open and parallel regional mapping catheter geometries. Graphs were generated based on varied mutual information thresholds between electrode pairs and the local efficiency for each graph was calculated.ResultsHigh-resolution mapping catheter geometries can distinguish between rotational and irregular activation patterns using the derivative of local efficiency as a function of increasing mutual information threshold. The derivative is decreased for rotational activation patterns comparing to irregular activations in both a simplified 2D model (0.0017 ± 1 × 10−4 vs. 0.0032 ± 1 × 10−4, p < 0.01) and a more realistic 3D model (0.00092 ± 5 × 10−5 vs. 0.0014 ± 4 × 10−5, p < 0.01). Average local efficiency derivative can also distinguish between degrees of remodeling. Simulations using the MSCSF model, with 10 vs. 90% remodeling, display distinct derivatives in the grid design parallel spline catheter configuration (0.0015 ± 5 × 10−5 vs. 0.0019 ± 6 × 10−5, p < 0.01) and the flower shaped open spline configuration (0.0011 ± 5 × 10−5 vs. 0.0016 ± 4 × 10−5, p < 0.01).ConclusionA decreased derivative of local efficiency characterizes rotational activation and varies with atrial remodeling. This suggests a distinct communication pattern in cardiac rotational activation detectable via high-resolution regional mapping and could enable identification of electrical drivers for targeted ablation.

Customized Radiofrequency Phased-Array Coil Combining Transmit-Only, Receive-Only, and Transmit/Receive Coils for Magnetic Resonance Imaging of Visual Cortex at 7 Tesla

Magnetic resonance imaging (MRI) using an ultra-high magnetic field (7 Tesla) enables detailed and non-invasive studies of the function and anatomy of the human visual cortex, which is the brain region responsible for visual signal processing. However, 7T human MRI often suffers from image shading in the occipital region due to the radiofrequency (RF) wave propagation effect. Dedicated visual cortex coils, on the other hand, often lack the capability to visualize the whole brain which is necessary for image registration. We propose a novel RF coil structure in which a 2-channel transmit and receive (TRx) coil is grafted onto the frontal part of a multi-channel transmit-only/receive-only (TORO, 4Tx/14Rx) visual cortex coil. This coil was tested for high-resolution functional MRI with an in-plane resolution of 0.5 mm. The results showed that the proposed coil achieved a higher ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 2.5$ </tex-math></inline-formula> ) temporal signal-to-noise ratio (tSNR) in functional imaging of the visual cortex area than that of a commercial 7T whole-head coil. The added 2-channel TRx elements allowed whole-brain edge images to be acquired, enabling successful brain segmentation and atlas registration without the need for a second scan using a whole-head coil. The proposed coil structure can be useful for high-resolution visual functional MRI at very high magnetic fields due to its sensitivity, open geometry, and compatibility with the standard image processing workflow.