Plate Orientation Research Articles

Optimization of curvilinear fiber orientation of composite plates and its experimental validation

Variable stiffness composite (VSC) is a viable design extension of carbon fiber reinforced plastic (CFRP) laminates to obtain unique mechanical properties by changing the fiber orientation in a curvilinear manner. We optimized a VSC for open-hole tension laminates considering the automatic processing by the tow prepreg curve placement and evaluated the strength improvement with experiments. Multi-objective optimization using fracture criterion and mean curvature as objective functions resulted in higher strength gains for solutions with higher mean curvature and lower processability. Besides, by giving the molding conditions as constraints for optimization, the strength was improved while satisfying the molding conditions. The fabrication of optimum VSCs involved using a tabletop automated fiber placement. Strength tests showed a 34.3% improvement in the curvilinear prepreg path.

Spatio-temporal evolution of hydroxyapatite crystal thickness at the bone-implant interface

A better understanding of bone nanostructure around the bone-implant interface is essential to improve longevity of clinical implants and decrease failure risks. This study investigates the spatio-temporal evolution of mineral crystal thickness and plate orientation in newly formed bone around the surface of a metallic implant. Standardized coin-shaped titanium implants designed with a bone chamber were inserted into rabbit tibiae for 7 and 13 weeks. Scanning measurements with micro-focused small-angle X-ray scattering (SAXS) were carried out on newly formed bone close to the implant and in control mature cortical bone. Mineral crystals were thinner close to the implant (1.8 ± 0.45 nm at 7 weeks and 2.4 ± 0.57 nm at 13 weeks) than in the control mature bone tissue (2.5 ± 0.21 nm at 7 weeks and 2.8 ± 0.35 nm at 13 weeks), with increasing thickness over healing time (+30 % in 6 weeks). These results are explained by younger bone close to the implant, which matures during osseointegration. Thinner mineral crystals parallel to the implant surface within the first 100 µm indicate that the implant affects the ultrastructure of neighbouring bone , potentially due to heterogeneous interfacial stresses, and suggest a longer maturation process of bone tissue and difficulty in binding to the metal. The bone growth kinetics within the bone chamber was derived from the spatio-temporal evolution of bone tissue's nanostructure, coupled with microtomographic imaging. The findings indicate that understanding mineral crystal thickness or plate orientation can improve our knowledge of osseointegration.

Coupled radiative and convective heat transfer in enclosures: Effect of inner heater–enclosure wall emissivity contrast

The problem of thermal radiation in the presence of nonuniform emissivity arising through different types surfaces involved in thermal-control systems is addressed. In particular, its effect on natural convection driven by an inner hot plate kept inside a square enclosure is studied. The enclosure considered is either horizontally or vertically cooled, and two different primary orientations of the inner hot plate are considered. The corresponding governing partial differential equations were solved by the finite volume method on a uniform and regular grid system. While doing so, the net radiation method was used to determine the radiative surface fluxes. The effect of two opposing emissivity contrasts between the inner hot plate and enclosure walls is studied for the Rayleigh numbers Ra ≤ 107. The flow and heat transfer mechanisms at the resulting steady state are discussed via isotherms, streamlines, and average Nusselt number Nu¯. The findings arrived out of this comprehensive study shows that prominent heat transfer enhancement occurs when the emissivity of the inner hot plate is higher. Significant changes introduced by the emissivity contrast in the velocity and temperature fields can be seen for higher Rayleigh numbers. Moreover, better heat removal through the combined radiation and convection mechanism is observed invariably for the vertical hot plate in the presence of emissivity contrast. It is found that the heat transfer can be augmented up to around 35% through a good knowledge of the emissivity contrast.

Multi-objective design optimization of variable ribs composite grid plates

Grid structures are among the most lightweight elements for stiffening the plates and shells or as self-sufficient structures. There are different known grid patterns, which are composed of variable numbers of parallel ribs. Selecting an optimum pattern and geometries for a grid to achieve the minimum weight and maximum load-bearing capacity is a challenging procedure for designers. In the current study, a variable ribs model (VRM) is proposed to find the optimum architecture of a grid plate. Therefore, using a genetic algorithm process, a multi-objective optimization is implemented to maximize the axial or shear buckling loads at a minimum possible weight of a grid structure. Eleven geometrical parameters including thickness, width, and the number of ribs as well as the orientation of the grid plate are considered the design variables. The multi-objective optimization is carried out employing the e-constraint method. The buckling loads are obtained based on the first-order shear deformation plate theory using the Ritz method.

A biomechanical study on the laminate stacking sequence in composite bone plates for vancouver femur B1 fracture fixation

Background and objectivesComposite bone plates are proposed for fracture fixation in periprosthetic femoral fracture. Metallic plates, having high stiffness compared to bone lead to stress shielding, reduce the compression force in the fracture site, affectthe healing process. Reduction of stiffness in the axial direction due to above reason without lowering the stiffness in transverse to avoid much of shear strain and thus avoiding instability at the fracture site leads to selective stress shielding. This can only be achieved through meticulously designed fiber reinforced composite. In the present work varied fiber orientations in the stacked laminates with varied fiber types are employed in a post-operative femur fixation for the in-silico analyses of their effectiveness using finite element analysis. MethodsIn this study a Total Hip Arthroplasty (THA) model is constructed with composite bone plates. Three-dimensional narrow type metal plate is modeled with 12 holes and length of 194 mm. Three different types of composite bone plates are modeled with 12 holes of different size for the analysis i.e. Type 1 (5.6 mm thickness and 16 mm width), Type 2 (6 mm thickness and 16 mm width) and Type 3(6 mm thickness and 18 mm width). Anatomical 3D FE models of THA with composite bone plates are constructed to find out the interfacial stresses and strains. The finite element software ANSYS is used to perform the analysis. ResultsA three-dimensional FE model of immediately post-operative femur fixation is developed and studied the maximum stress distribution, strain and movement in axial/shear direction in the metal and composite bone plate near to the fracture site. In the present study, the metal and composite plate (carbon/epoxy, glass/epoxy and flax/epoxy) used for most common Vancouver type B1 fracture to observe the biomechanical behavior of different models in IPO condition using FEA. ConclusionsOptimizing the fiber orientations of composite bone plates of Total Hip Arthroplasty (THA) model by controlling the biomechanical stresses could be a favorable approach. The finite element analysis approach gives a viable solution to design the composite bone plate and for designing future models that preserves the biomechanical function of THA with composite bone plate.

A Novel Design of Liquid Volumetric Plated Cavity Receiver for Central Tower Systems

Abstract Previously reported studies have shown that the volumetric receivers have lower radiative and convective losses, leading to higher efficiency. However, the conventional volumetric receivers are difficult to use along with the thermal storage systems, owing to the use of air as the heat transfer fluid. Molten salt, having high heat capacity, emerges as a suitable candidate to be employed as the heat transfer fluid and for storing thermal energy in the storage devices. It is challenging to use the molten salt in the conventional volumetric receiver configuration; therefore, a novel design called Liquid Volumetric Plated Cavity Receiver is proposed, where the solar salt is used as heat transfer fluid. It consists of a parallel arrangement of hollow plates in an open cavity. Solar radiation concentrated by the heliostat field is absorbed on the outer surface of the hollow plates. The heat is then taken away by the molten salt flowing inside the hollow plates. The plates are arranged such that the molten salt gets heated up within the volume of the enclosure, effectively mimicking the heating performance of the volumetric receivers. Using an analytical model for heat losses, it is observed that the losses are very sensitive to the aspect ratio of the aperture and depth of the receiver. The effects of receiver inclination, plate orientations, radiation incident at the aperture, and surface emissivity have been investigated as well. The results show that a Liquid Volumetric Plated Cavity Receiver increases the efficiency (by ∼3%) as compared with that of the simple cubic receiver.

Understanding the Impact of Test Configuration on Welded-Wire Mesh Laboratory Test Results

Underground mines use a combination of rock reinforcement and surface support elements to maintain the structural integrity of excavations in rock. The design of an effective ground support system requires an understanding of the mechanical behaviour of individual ground support components and how they interact under load. This paper reviews the mechanical behaviour of welded wire steel mesh routinely used in underground mines. It further reviews the advantages and limitations of using testing rigs used to quantify the performance of mesh. In particular, it illustrates the impact of rig configuration and testing parameters on mesh performance. The main focus of this work is the development and calibration of 3D discrete element method of numerical models capable of reproducing mesh behaviour under specific testing configurations. The developed models successfully reproduced the load redistribution on the mesh wires, the load–displacement response, and failure mechanisms observed in laboratory tests. The calibrated models were subsequently used to determine the impact of testing rig configurations, including loading plate dimensions and orientation, and mesh dimensions on the performance of mesh under load. This work has significant practical implications on how to interpret results obtained from different testing rigs. Furthermore, the results of this work can provide guidance towards designing new testing rig configurations as well as demonstrating the need for the development of testing methods and procedures. Finally, it illustrates the challenges that have to be overcome if the explicit modelling of mesh will be a reliable part of the ground support design process.

Smart Material Hydrogel Transfer Devices Fabricated with Stimuli-Responsive Silk-Elastin-Like Proteins.

Three-dimensional organoid tissue culture models are a promising approach for the study of biological processes including diseases. Advances in these tissue culture technologies improve in vitro analysis compared to standard 2D cellular approaches and are more representative of the physiological environment. However, a major challenge associated with organoid systems stems from the laborious processing involved in the analysis of large numbers of organoids. Here the design, characterization, and application of silk-elastin-like protein-based smart carrier arrays for processing organoids is presented. Fabrication of hydrogel-based carrier systems at room temperature result in organized arrays of organoids that maintain tissue culture plate orientation and could be processed simultaneously for histology. The system works by transfer of the organoids to the hydrogel arrays after which the material is subjected to 65°C to induce hydrogel contraction to secure the organoids, resulting in multisample constructs and allowing for placement on a microscope slide. Histological processing and immunostaining of these arrayed cerebral organoids analyzed within the contracted silk-elastin-like proteins (SELP) show retention of native organoid features compared to controls without the hydrogel carrier system, thus avoiding any artifacts. These SELP carriers present a useful approach for improving efficiency of scaled organoid screening and processing.

Input polarization-independent polarization-sensitive optical coherence tomography using a depolarizer.

Polarization-sensitive optical coherence tomography is gaining attention because of its ability to diagnose certain pathological conditions at an early stage. The majority of polarization-sensitive optical coherence tomography systems require a polarization controller and a polarizer to obtain the optimal polarization state of the light at the sample. Such systems are prone to misalignment since any movement of the optical fiber normally coupled to the light source will change the polarization state of the incident beam. We propose and demonstrate an input polarization-independent polarization-sensitive optical coherence tomography system using a depolarizer that works for any input polarization state of the light source. The change in the optical power at the sample for arbitrary input polarized light for the standard polarization-sensitive optical coherence tomography system was found to be approximately 84% compared to 9% for our proposed method. The developed system was used to measure the retardance and optical axis orientation of a quarter-wave plate and the obtained values matched closely to the expectation. To further demonstrate the capability of measuring the birefringent properties of biological samples, we also imaged the nail bed. We believe that the proposed system is a robust polarization-sensitive optical coherence tomography system and that it will improve the diagnostic capabilities in clinical settings.

Microstructure and crystallography of the wall plates of the giant barnacle Austromegabalanus psittacus: a material organized by crystal growth.

In biomineralization, it is essential to know the microstructural and crystallographic organization of natural hard tissues. This knowledge is virtually absent in the case of barnacles. Here, we have examined the crystal morphology and orientation of the wall plates of the giant barnacle Austromegabalanus psittacus by means of optical and electron microscopy, and electron backscatter diffraction. The wall plates are made of calcite grains, which change in morphology from irregular to rhombohedral, except for the radii and alae, where fibrous calcite is produced. Both the grains and fibres arrange into bundles made of crystallographically co-oriented units, which grow onto each other epitaxially. We call these areas crystallographically coherent regions (CCRs). Each CCR elongates and disposes its c-axis perpendicularly or at a high angle to the growth surfaces, whereas the a-axes of adjacent CCRs differ in orientation. In the absence of obvious organic matrices, this pattern of organization is interpreted to be produced by purely crystallographic processes. In particular, due to crystal competition, CCRs orient their fastest growth axes perpendicular to the growth surface. Since each CCR is an aggregate of grains, the fastest growth axis is that along which crystals stack up more rapidly, that is, the crystallographic c-axis in granular calcite. In summary, the material forming the wall plates of the studied barnacles is under very little biological control and the main role of the mantle cells is to provide the construction materials to the growth front.

Wave plate-dependent lasing regimes transitions in an all-normal-dispersion fiber laser mode-locked by nonlinear polarization rotation

We address the transitions between three different working regimes of an all-normal-dispersion pulsed fiber laser, mode-locked by nonlinear polarization rotation (NPR). In particular, we investigate numerically the dynamics and study in details the transitions induced by solely rotating the cavity wave plates. We analyze the phemomenon by putting forward a model for all-normal-dispersion NPR-moded-locked fiber laser, based on the coupled Ginzburg-Landau equations and Jones matrix. Numerical results show that depending on the values of the cavity parameters, the transitions between the dissipative soliton regime and amplifier similariton one, or the transition between the dissipative soliton regime and the splitting pulse one may be realized by simply rotating the cavity wave plates. We found that the transitions are intrinsically related to the NPR mode-locking mechanism by explicitly evaluating the polarization states across the pulse at different locations of the cavity. Our numerical results are in very good agreement with experimental results reported in the relevant literature, and provide evidence that besides gain saturation and spectral filtering, the orientations of wave plates may be exploited as a suitable degree of freedom to obtain the desired pulse regimes in all-normal-dispersion fiber lasers.

Evaluation of Buckling Resistance of Basalt Fiber Reinforced Polymer Plate

Basalt fiber reinforced polymer (BFRP) is known as an excellent material used to strengthen reinforced concrete structures. BFRP is attached to beam, slab or column, which would be subject to compressive and bending load. Since the thickness of BFRP plate is relatively thin, the buckling problem is a concern. However, investigation of mechanical properties and buckling resistance of BFRP plate has been very limited. In this paper, the mechanical properties of BFRP were experimentally investigated using tensile test and in-plane shear test. Because the mechanical properties of BFRP depend on the type of resin, three types of BFRP: basalt/polyester, basalt/vinyl ester and basalt/epoxy, were used in a tensile test to optimize the resin. To evaluate the buckling behavior of BFRP plate, a numerical approach was established using the finite element method. The results of the mechanical properties of BFRP were then used to determine the buckling resistance. Based on the experimental results, the tensile strength of BFRP that consisted of basalt/epoxy was 4.8% and 2.4% greater than those consisting of basalt/polyesters and basalt/vinyl ester, respectively. It was also found that the elastic modulus of BFRP was approximately 11.26% larger than that of GFRP. The numerical results indicated that the buckling resistance of BFRP plate was 10.3% to 10.7% greater than that of GFRP depending on loading condition, fiber orientation, aspect ratio and boundary condition of the laminate plate. Therefore, using BFRP laminate composite plate in retrofitting of concrete structure provides better performance than GFRP in terms of mechanical properties and buckling performance.

Factors Influencing Muon Flux and Lifetime: An Experimental Analysis Using Cosmic Ray Detectors

Muons, one of the fundamental elementary particles, originate from the collision of cosmic rays with atmospheric particles and are also generated in particle accelerator collisions. Muon flux and lifetime are usually analyzed to obtain important insights regarding time dilation and to ascertain the characteristics of the particles and processes that occur during collision. In this study, we analyzed the factors that influence muon flux and lifetime using Cosmic Ray Muon Detectors (CRMDs). We hypothesized that the positioning of cosmic ray detector scintillator plates and depth of water above such scintillator plates would affect muon flux and lifetime. Muon flux and lifetime would be affected as an increase in matter in the path of a muon would slow or stop muons passing through it. Altering liquid shielding indicated that muon flux was inversely related to the depth of water that it passed through. Altering scintillator positioning indicated that detection rates of muon decay increased with the distance between the top and bottom of the scintillator plates resulting from the scintillator plate orientation. Unlike previous studies, the effects of the shielding were noticeable at smaller scales. Overall, this study suggests that water can be used to decrease muon flux and that the scintillator orientation is a potential determinant of the volume of data collected in muon decay studies.

Mueller matrix ellipsometry study of a circular polarizing filter

The authors introduce an ellipsometric data analysis strategy for a flexible polymeric circular polarizing filter consisting of a thin linear polarizer and quarter-wave plate sandwich. The circular polarizing filter is an inhomogeneous optical system exhibiting different optical responses depending on the propagation direction of light. If light enters from the linear polarizer, the transmitted beam is linearly polarized before entering the quarter-wave plate. The orientation of the quarter-wave plate is rotated 45° from the linear polarizer axis. The emerging light from the quarter-wave plate is circularly polarized. If light is circularly polarized and enters from the reserve side, the quarter-wave plate converts it into linearly polarized light. The following linear polarizer either transmits or absorbs the beam depending on the handedness of the original circular polarization. The optical response in the forward direction is utilized in photography to reduce unwanted reflections in the image. The optical response in the reverse direction is utilized in 3D eyeglasses, which consist of two orthogonal circular polarizing filters to separate the left and right images. Mueller matrix spectroscopic ellipsometry is used to observe the optical responses of a circular polarizing filter in both directions. The authors demonstrate data analysis procedures for individual layers to find the optical constants in a wide spectral range from 400 to 1700 nm. The circular polarizing filter measured in the forward direction enables ellipsometry to determine the included angle between the linear polarizer and the quarter-wave plate. The ellipsometric data analysis result is used to predict transmitted light intensity versus rotation angle (deg) with respect to any input polarization state.

Effect of Orientation and Aspect Ratio of an Internal Flat Plate on Natural Convection in a Circular Enclosure

This work presents a numerical investigation on natural convection in a circular enclosure with an internal flat plate at Ra = 106. The cross-section area of the plate was fixed at three values, H·W/D2 = 0.01, 0.04, and 0.09, in which H and W are the height and width of the plate and D is the diameter of the enclosure while the aspect ratio changes, which makes the plate vertically placed (H > W) or horizontally placed (H < W). The objective of this work was to explore the effects of the orientation and aspect ratio of the plate on the characteristics of natural convection in various aspects. The numerical results reveal that the overall heat transfer rate is higher for the vertically placed plate and increases with the cross-section area, while the width of the plate has almost no effect for the horizontally placed plate, especially for the plate with a relatively large cross-section area. Depending on the orientation and aspect ratio, there can be one primary vortex, one primary and one secondary vortex, or one secondary and two separated vortices to each side of the plate, and the thermal plume structure may appear at the sharp top corners of the plate. Consequently, local heat transfer on the surfaces of the enclosure and plate is affected. Synergy analysis reveals that the enhancement of heat transfer from the fluid circulation is the most significant at the center of the vortices and at the boundary between them.

Performance comparison of a structured bed reactor with and without a chimney tray on the gas-flow maldistribution: A computational fluid dynamics study

In the present paper, two configurations of structured reactors (with and without) chimney tray placed below the packed bed have been investigated to study their effect on maldistribution factor and pressure drop characteristics. A simulation result based on a three-dimensional computational fluid dynamics was involved using ANSYS Fluent. First, maldistribution factors without chimney tray were calculated and compared to the results taken from the literature. The results were found to be in good agreement with the experimental data of Yuan et al. Second, the reactor with a chimney tray was modeled in Fluent, and steady-state simulations were performed. The uniformity due to the turbulence of the fluid was carried out using different turbulence models, and the velocity profiles along the axial direction inside the reactor were obtained. As a result, the comparison shows that the presence of a chimney tray yields lower maldistribution factor enhancement by 23% compared to the conventional structured reactor under the same operating condition. The effect of the plate orientation is also determined, and it is found that the maximum pressure drop is achieved through the rows with an orientation angle of α = 45° up to 2.3% higher than of α = 0° and α = 90°.

Predicting growth plate orientation with altered hip loading: potential cause of cam morphology.

Proximal femoral deformities can result from altered hip joint loading patterns during growth. The growth plate hyaline cartilage has low resistance to shear stress. Therefore, we hypothesized that the growth plate orients in a direction which minimizes the shear stress on its surface. A finite element model of the proximal femur was generated with a simplified flat growth plate. Hip joint forces were estimated for standing upright and standing in hip flexion. We also parametrically studied the effects of posteriorly and laterally directed loads. An algorithm was developed to predict the shape of the femoral growth plate in a plane of minimum shear (along the principal stress vectors). To characterize and compare the growth plate shapes, we represented the distance from the growth plate to a reference plane as a two-dimensional contour plot, providing information of shape and orientation across the entire surface. We also assessed the clinical measures of growth plate shape to compare our predicted growth plates with previous clinical studies data. The shape of the growth plate predicted for an upright standing load correlated closely with morphological properties of the growth plane of a typically developing child. The shape of the growth plate predicted for femoral hip flexion force was similar to the growth plate in subjects with cam morphology, a hip shape that has documented growth plate changes. The model proposed here allows for investigation of the relation between joint forces and growth plate shape, which will help predict the development of bony deformities.

An automatic genetic algorithm framework for the optimization of three-dimensional surgical plans of forearm corrective osteotomies.

Three-dimensional (3D) computer-assisted corrective osteotomy has become the state-of-the-art for surgical treatment of complex bone deformities. Despite available technologies, the automatic generation of clinically acceptable, ready-to-use preoperative planning solutions is currently not possible for such pathologies. Multiple contradicting and mutually dependent objectives have to be considered, as well as clinical and technical constraints, which generally require iterative manual adjustments. This leads to unnecessary surgeon efforts and unbearable clinical costs, hindering also the quality of patient treatment due to the reduced number of solutions that can be investigated in a clinically acceptable timeframe. In this paper, we propose an optimization framework for the generation of ready-to-use preoperative planning solutions in a fully automatic fashion. An automatic diagnostic assessment using patient-specific 3D models is performed for 3D malunion quantification and definition of the optimization parameters' range. Afterward, clinical objectives are translated into the optimization module, and controlled through tailored fitness functions based on a weighted and multi-staged optimization approach. The optimization is based on a genetic algorithm capable of solving multi-objective optimization problems with non-linear constraints. The framework outputs a complete preoperative planning solution including position and orientation of the osteotomy plane, transformation to achieve the bone reduction, and position and orientation of the fixation plate and screws. A qualitative validation was performed on 36 consecutive cases of radius osteotomy where solutions generated by the optimization algorithm (OA) were compared against the gold standard solutions generated by experienced surgeons (Gold Standard; GS). Solutions were blinded and presented to 6 readers (4 surgeons, 2 planning engineers), who voted OA solutions to be better in 55% of the time. The quantitative evaluation was based on different error measurements, showing average improvements with respect to the GS from 20% for the reduction alignment and up to 106% for the position of the fixation screws. Notably, our algorithm was able to generate feasible clinical solutions which were not possible to obtain with the current state-of-the-art method.

Macrofouling Development on Artificial Structure at Karambunai Bay, Sabah Malaysia

This study investigates macrofouling development on PVC panels deployed in Karambunai, Sabah. The experimental setup includes two sets of connected PVC pipes, framed in a triangular shape, attached to concrete blocks deployed on the seafloor and kept afloat vertically underwater. The first set (upper) of frame positioned 2 m below the surface whereas the second set (bottom) attached 8 m below it. A total of 36 PVC plates measuring 20 cm x 27 cm were tied on each three sides of the two sets of frames. To investigate monthly macrofouling development, three panels were taken from each side of the two frames. This experiment lasted 180 days, starting from end of April to October 2017. As a result, a total of ten different species were identified growing on the front side and the back side of the plates at 2 m and 8 m. The total biomass of macrofouling assemblages at 2 m and 8 m had a significant (P<0.05) positive correlation (0.89), suggesting that there was no significant difference of total biomass between two different depths. For macrofouling community, diversity indices showed similar values for both sides of the plates at 2 m and 8 m, indicating that depth and plate orientation had no influence on the distribution pattern of macrofouling growth.

A comprehensive geometrical study on an induced-charge electrokinetic micromixer equipped with electrically conductive plates

In this paper, a numerical study is performed on an induced-charge electrokinetic micromixer. The electrically conductive plates are installed inside the micromixer to induce vortices that improve the mixing index of the system. A comprehensive geometrical study is performed on this micromixer and the effects of various parameters are investigated. These parameters include the mounting, length, orientation, position, arrangement and number of the conductive plates, and the intensity of the external electric field. To benchmark the accuracy of the numerical model, the simulated results are compared and agree well with existing experimental and numerical data in the literature. The results show that a mixing efficiency of 99.6% can be achieved by placing two 5° angle conductive plates near the upper and lower walls and one 5° angle conductive plate at the center of the micromixer. It is also observed that the mixing performance increases with increasing conductive plate length. The mixing efficiency can be improved from 67.2% to 94.3% by increasing the plate angle from 0° to 40°. Combining these optimizations, close to 100% mixing efficiency can be achieved by placing three staggered and tilted conductive plates at an angle of 5°.