Perforated Metal Plate Research Articles

Air Flows along Perforated Metal Plates with the Heat Transfer

Air Flows along Perforated Metal Plates with the Heat Transfer

Development of a New Method for Producing Plane Expanded Metal by Laser Cutting and Forming of Metal Plates under Uniaxial Tension

The on-going trend to lightweight construction leads to a special focus on plane lattice structures as an alternative for solid metal plates. They demonstrate similar mechanical properties while taking up only a fraction of the normal material input and are thus economically favourable. Additionally, they fulfil functional and design aspects and therefore are used by several industries like the automobile. Nevertheless, the two most common types of lattice structures – perforated metal plates and expended metal plates – are either waste intensive or uneven and hence require additional rolling of the metal plate.Therefore, within this contribution a new and innovative approach for the production of plane lattice structures will be presented. The manufacturing process thereby consists of two steps. At first, a specially designed pattern is cut into metal plates via a laser. Subsequently, the plates are formed under uniaxial tension to realize the lattice structures. Based on the cutting length, cutting space and the row space different blanks with tailored lattice structures can be produced. From the experimental results first guidelines for the design of suitable patterns are derived. The investigations will be performed with precipitation hardenable aluminium AA6014.

Reinforcement of polymethylmethacrylate (PMMA) resin with perforated metal plates

Reinforcement of polymethylmethacrylate (PMMA) resin with perforated metal plates

Wire mesh current collectors for passive direct methanol fuel cells

This paper examines the feasibility of the stainless steel wire mesh as current collector in the passive direct methanol fuel cell (DMFCs-W). A novel single cell fixture is designed and fabricated. The cell performance is evaluated and compared with five different wire mesh current collectors. The supporting plates are optimized for every mesh. The performance of DMFCs-W is compared with the conventional passive DMFC which uses perforated metal plate as current collector (DMFC-P). The polarization tests and electrochemical impedance spectroscopy are performed to investigate the different aspects of the cell performance. The results reveal that the DMFCs-W yield better performance than the DMFC-P. Also, more uniform fuel distribution at catalyst layer and higher cell temperature is achieved with wire mesh current collectors. It is found that the wire mesh geometry has significant effect on the cell performance and the mesh made of relatively thick wires gives better cell performance. This study identifies the stainless steel wire mesh as promising material to be used as current collector and potential substitute to the perforated plate current collectors in the passive DMFC.

Influence of Perforated Metal Plate on Pressure Rise and Energy Flow due to Internal Arcing in a Container With a Pressure-Relief Opening

Internal arc tests and computational fluid dynamics' calculations regarding the effect of a perforated metal plate (absorber) on pressure rise and propagation in a container with a pressure-relief opening are carried out. In the calculations, the perforated metal plate is simply considered as a medium of gas-flow resistance and a heat sink/conductor. The pressure development at different locations within the container, and the maximum pressure rise PMAX and the mean pressure value PMEAN are measured and calculated by changing the aperture ratio RAP of the perforated metal plate and the cross-sectional area AOP of the pressure-relief opening. In addition, the energy flow density EFOP and the total energy flow QOP at the opening depending on RAP and AOP are estimated. From the following investigations, it is necessary to consider the dependence of the ratio PMAX to PMEAN on the value of RAP, and the dependence of EFOP and QOP on the value of AOP, when designing electric power equipment.

Simple Modelling and Characterization of Pressure Rise due to Internal Arcing in an Open Chamber with Releasing Through a Metal Grid

In some electrical installations equipped with the pressure relief mechanism for the internal arcing fault, metal grids are set up at the releasing parts. So it is necessary to understand how the pressure in such electrical installations rises during the internal arcing fault. This paper describes an investigation of the internal pressure rise due to the high current arc in an open chamber with releasing through a metal grid. In this investigation, we focused on both the peak value Ppeak and the time to peak tpeak on the internal pressure rise waveform where the oscillating component was removed, because it was experimentally observed that the general variation of such internal pressure rise with time had a point of turning from growing to lessening during the arcing. In order to investigate such internal pressure rise, a simple model for calculation was constructed, and was validated by a comparison with data from the experiment using a perforated metal plate as a metal grid. As a result of the investigation applying this simple model, the dependence of both the Ppeak and the tpeak on conditions of the metal grid, the chamber volume, and the arc energy was derived quantitatively.

PDMS, A Robust Casing for Flexible W-BAN Antennas [EurAAP Corner

This paper describes a new technology for the realization of soft, flexible, and robust antennas intended to operate in a harsh environment. One of the main characteristics of the proposed technology is the ease of fabricating antennas in a simple lab environment. The method is based on the use of a silicon-based elastomer, polydimethylsiloxane (PDMS), for the substrate material, and copper meshes or any kind of perforated metal plates as flexible conductive materials. The initial liquid state of the PDMS allows a lot of freedom in the fabrication process, both from the electrical and mechanical points of view. The electrical and mechanical properties of the substrate can be adjusted by loading the PDMS with inclusions having low or high permittivity and/or density, thus controlling the permittivity and the rigidity. Another good characteristic of the initial low viscosity of PDMS is the possibility of shaping the antennas and substrates in in-house fabricated moulds. Copper meshes or perforated metal structures enable good adhesion between the substrate and 288 IEEE Antennas and Propagation Magazine, Vol. 55, No. 5, October 2013 conductor, and improve the overall flexibility. Measured results showed good repeatability of the substrate samples, both with or without inclusions. To demonstrate the versatility of the proposed technique, several antenna prototypes were built and characterized. All the antennas were flexible and showed good radiation characteristics. The antennas were exposed to tests such as washing and bending, in order to assess their robustness to environmental changes.

Metamaterial filters at optical-infrared frequencies

We propose two distinctive designs of metamaterials demonstrating filtering functions in the visible and near infrared region. Since the emissivity is related to the absorption of a material, these filters would then offer a high emissivity in the visible and near infrared, and a low one beyond those wavelengths. Usually, such a system find their applications in the thermo-photovoltaics field as it can find as well a particular interest in optoelectronics, especially for optical detection. Numerical analysis has been performed on common metamaterial designs: a perforated metallic plate and a metallic cross grating. Through all these structures, we have demonstrated the various physical phenomena contributing to a reduction in the reflectivity in the optical and near infrared region. By showing realistic geometric parameters, the structures were not only designed to demonstrate an optical filtering function but were also meant to be feasible on large surfaces by lithographic methods such as micro contact printing or nano-imprint lithography.

Enhancement of Faraday and Kerr rotations in three-layer heterostructure with extraordinary optical transmission effect

We theoretically investigate and optimize a multilayer planar structure with enhanced magneto-optical (MO) activity. The extraordinary optical transmission observed in a periodically perforated metal plate with subwavelength holes is used to produce a higher MO activity. We consider a three-layer structure that consists of a dielectric layer placed between the perforated metal and the MO layers. In this structure, we obtained the enhancement of Faraday rotation by three times and the Kerr effect by an order as compared to the published results.

Vadose Zone Soil Moisture Wicking Using Super‐Absorbent Polymers

Super‐absorbent polymers (SAPs) have the potential to remove water and associated contaminants from unsaturated sediments. Laboratory experiments were conducted to test four types of SAPs. Column experiments, with a layer of polymer on top of unsaturated porous media, showed the ability of the SAPs to extract up to 80% of initial water during periods up to 4 wk. In column experiments where the sorbent was emplaced between layers of unsaturated porous media, gel formation was observed at both the sorbent–porous medium interfaces. The extraction percentages were similar for both configurations and no obvious differences were observed for the four SAPs. Two flow cells were used to test the wicking behavior in two dimensions using three configurations. The largest removal percentages occurred for the horizontal sorbent layer configuration, which had the largest interfacial area. In a larger flow cell, a woven nylon “sock” was packed with sorbent and placed between perforated metal plates, mimicking a well configuration. After 1 wk of contact time, the sock was removed and replaced by a fresh sock. The results showed that the sorbent was able to continuously extract water from the porous media, although the rate decreased with time. The declining yield was associated with the sharp reduction in water saturation and relative permeability near the sorbent. The capillary pressure continued to increase during the total contact time, indicating that the sorbent remained active during that period. This work has demonstrated the potential of soil moisture wicking using SAPs at the proof‐of‐principle level.

Collimation effect inside complete bandgap of electromagnetic surface resonance states on a metal plate perforated with a triangular array of air holes

In this paper the transmission properties of a metal plate perforated with a triangular array of air holes is investigated. We find that the normalized transmittivity exceeds unity within a certain frequency range under normal incidence of a Gaussian beam. Calculations and experiments indicate that the phenomenon results from the collimation effect which only occurs inside the complete bandgap of surface resonance states on the perforated metal plate. The findings present a simple approach for beam collimation.

Grain storage: methods and measurements

Reducing post-harvest losses is considered as a major step towards food security. However, losses vary significantly by climatic region, country, crop and of course the infrastructure and methods of storage followed. In India, the post-harvest losses of food grains amount to more than 20 million tons per year, which is approximately 10% of the total food grains produced. This can be attributed to the poor infrastructural facility and unscientific methodologies followed for food grain storage in the country. In a country where about 20% of the population is undernourished, post-harvest losses of 20 million tons annually is a substantial avoidable waste. Safe grain storage methods play a crucial role in preventing losses caused mainly by weevils, beetles, moths and rodents. It is estimated that 60–70% of food grain produced in the country is stored at domestic level. To ensure safe and scientific storage, careful selection of storage site, storage structure and proper aeration of grains, regular inspection of grain stock, cleaning and fumigation needs to be performed when required. Traditionally two approaches are employed for grain storage in India: temporary and long-term storage methods. Under temporary storage, aerial storage, storage on the ground or on drying floors and open timber platforms which is normally done at farm level are followed, whereas under long term storage, methods storage baskets (cribs) made exclusively of plant materials, calabashes, gourds, earthenware pots, jars, solid wall bins and underground storage can be employed. Bulk storage of produce is done in warehouses owned by the Food Corporation of India (FCI) and the Central and State Warehousing Corporation (CWC/SWC). Warehouses are scientific storage structures especially constructed for the protection of the quantity and quality of stored products. Under bulk storage, sealing and aeration play an important role. Aeration may be ambient or refrigerated based on the requirement. Over 420 standard test methods including more than 75 internationally accepted methods are available to test the quality of stored grains. Of the wide range of properties used for testing, the bulk density and the foreign matter are commonly assessed for most grain types. For foreign matter content analysis, the screens of sieves used for the assessment should consist of perforated metal plate conforming to specifications laid down by national or international standards organizations. Moisture content is another important parameter which should be considered during grain quality analysis. The indigenous storage structures are not suitable for storing grains for very long periods. Thus, improved storage structures and scientific storage of grains in form of warehouses is the need of the hour to strengthen traditional means of storage with modern inputs and to provide cheaper storage facility to farmers as well as to prevent enormous storage losses.

Sound Attenuating Shield for an Electric Heater

A sound-abating flow disruptor quiets a PTAC refrigerant system by disturbing the airflow between an energized electric heater and an adjacent fan wheel. In some embodiments, the flow disruptor is a perforated metal plate that attenuates a whistle, which appears to be caused by vortex shedding in the confined area between the energized heater and the fan. In some cases, the heater comprises selectively energizable heating elements of various wattage. The heating elements closest to the fan wheel are the lower wattage ones to minimize the heat near the fan.

Multiple extraordinary optical transmission peaks from evanescent coupling in perforated metal plates surrounded by dielectrics

We study numerically and theoretically the optical transmission of nanostructured gold films embedded in dielectric claddings. We show how multiple transmission peaks appear as the claddings thickness increases. These transmission peaks come not only from surface plasmon polariton excitations but also from the excitation of Fabry-Perot modes sustained at the claddings, coupled through the metal, as long as a periodic pattern is milled in the metal film. We propose that this structure could be used as an ultracompact all-optical switch by surrounding the metal film with Kerr nonlinear dielectric layers.

Hydrodynamic Characteristics of a Sparged Gas−Liquid Contactor for Fine Bubble Generation

In this study, hydrodynamics of a gas−liquid bubble column with a following sparger made of ceramic, a perforated metal plate, brick material, and polypor porous material has been presented. Experiments were conducted for water levels of 100, 125, and 150 cm with and without the addition of frother. An attempt has been made to investigate the hydrodynamics of the downward flow of a high-pressure water jet at different jet heights and different water velocities. The column was operated with air at superficial gas velocities in the range of 0.122−3.7 cm/s. Effects of superficial gas velocity, frother doses, and jet height on gas holdup have been presented. Depending on experimental operating conditions for gas holdup, flow regimes were identified for different spargers. Experimental results shows that a ceramic type sparger has better gas holdup compared to other spargers. It was also found that gas holdup is greater with the addition of frother (70%) compared to that without addition of frother (20%).

Effect of Partial Debonding on Response of Perforated Plates Repaired with Square Composite Patches

The performance of perforated metallic plates repaired with laminated composite patches is presented in this study. A square aluminum plate with a central circular cutout is considered as a damaged structural element. Numerical studies using commercial finite element code were conducted to investigate the effects of variation in laminate parameters such as number of plies, fiber orientation, and stacking sequences on free vibration responses of the repaired plates. Particular emphasis is placed on the effect of imperfect bonding (patch debonding). A quantitative measure for the effectiveness of the composite patches parameters is taken to be the relative change in natural frequencies of the deboned patches compare to the patches with perfect bonding. The results presented herein indicated that, vibration response of a repaired perforated metallic plate is affected by the number of plies, stacking sequences of the patch and the quality of bonding between the patch and the base plate.

Flutter of Perforated Metallic Plates Repaired with Cross-Ply Composite Patches

This study investigates the application of laminated composite patches for enhancement of flutter behavior of perforated metallic plates repaired with an external composite patch. Due to material anisotropy and discontinuity in geometry involved in flutter analysis of repaired plates, closed form solutions are practically unobtainable. Numerical studies using commercial finite element software were conducted to investigate the effects of variation in lamination parameters on the flutter boundary of perforated plates repaired with cross-ply composite patches. Both ply-level and sub-laminate level configurations are investigated. Presented results illustrate that flutter boundaries of perforated plates can be changed by choosing proper stacking sequence for composite patches.

Microplasma-Induced Deformation of an Anomalous Response Spectrum of Electromagnetic Waves Propagating along Periodically Perforated Metal Plates

Metal plates with two-dimensional hole arrays showed unusual responses of electromagnetic waves, and in this study microplasmas were generated in the holes to deform their properties dynamically and to induce novel frequency-dependent permittivity. Transmitted electromagnetic waves in millimeter wavelength range exhibited attenuation of anomalous transmittance around cutoff frequency of equivalent waveguide when microplasmas were present. On the contrary, the reflected waves were significantly enhanced around such a frequency, where reflectance is at minimum in the case without microplasma generation. These experimental results indicated resonance phenomenon which is usually called spoof surface plasmons, and dynamic change of dielectric constant in the medium inside the holes induced by microplasmas shifts their resonance frequency.

On the Common Nature of the Enhanced and Resonance Transmission Through the Periodical Set of Holes

For the explanation of the enhanced transmission through the perforated metal plate with below-cutoff holes, the eigenoscillations of the double-periodic screen are studied. It is found that the origin of the recently discovered effects is the existence of the eigenoscillations of the interface between the free halfspace and the metal halfspace perforated with double-periodic set of channels and the formation of the corresponding symmetrically and anti-symmetrically coupled ldquosupermodesrdquo when two such interfaces form a screen of finite thickness. The amplitude and polarization structure of the eigenfields and the behavior of the complex-valued eigenfrequencies depending on the geometry parameters are studied by the mode-matching technique (MMT) both for a finite-thickness screen and for an interface. The symmetrical oscillation of the perforated screen is shown to be the cause of both the well-known phenomenon of total transmission through frequency selective surfaces (FSS), and the recently discovered enhanced transmission through cutoff holes. When the holes shrink, the field pattern of this eigenoscillation transforms from the one concentrated within the holes to that concentrated in the form of Floquet-waves above and below the screen, i.e., out of the holes. In contrast, the antisymmetrical oscillations are always located in frequency near the Floquet-waves grazing points at any hole dimensions and cause the so-called Wood anomalies.

Evaluierung von Kleingruppenhaltungssystemen und ausgestalteten Käfigen hinsichtlich Brustbeindeformationen, Gefiederstatus, Krallenlänge und Körpermasse bei den Legelinien Lohmann Selected Leghorn und Lohmann Brown

Abstract. Title of the paper: Evaluation of small group housing systems and furnished cages concerning keel bone deformities, plumage condition, claw length und body weight in layer strains Lohmann Selected Leghorn and Lohmann Brown Small group housing systems (Eurovent 625+a-EU) and furnished cages (Aviplus und Eurovent 625A-EU) were evaluated for the occurrence of keel bone deformities, plumage condition, claw length and body weight. The examinations were performed in two layer strains, Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB), over two laying periods. In addition, the effects of layer strain, month of laying period, rearing method, group- size and body weight on these traits were tested. The assessments based on a scoring system comprising the scores 1 (very severely defective part of the body) to 4 (intact part of the body) were performed every three months during the laying period. Examinations of keel bone condition and measurements of body weight were performed in a total of 864 hens, claw length and plumage condition were examined in a total of 720 hens. Housing system showed a significant effect on the incidence of keel bone deformities and claw length. Plumage condition was significantly affected by group size, whereas plumage condition was worst in groups of 20 hens in Aviplus and in groups of 10 hens in Eurovent 625A-EU. Concerning claw length there were significant differences between diverse claw abrasives. The strongest abrasion was found in groups with two abrasive blocks, whereas perforated metal plates led to the least abrasion. Month of laying period showed a significant effect on each examined trait with a decrease in keel bone and plumage condition and an increase in claw length and body weight during the laying period.