Reflective Plate Research Articles

Conceptualization of the Micro Research Reactor Cooled by Heat Pipes (MRR-HP), Part-I: neutronics analyses

ABSTRACT This work aims to introduce a new neutrons source technology for research and medical applications, by the conceptualization of the Micro Research Reactor cooled by Heat Pipes (MRR-HP). This is achieved by developing a 3D-detailed neutronics model using the Monte-Carlo Serpent-2.1.31 code, and investigating the neutronics behavior and define the design parameters of the MRR-HP. The MRR-HP is a cylindrical monolithic block (Magnesium-Oxide) that includes; fuel rods (Uranium-Nitride), Dummy Rods (Beryllium-Oxide), Water and Potassium heat pipes for cooling. The monolithic block is surrounded by reflector (Beryllium-Oxide), where moveable reflective bent plates and a cylindrical block are inserted for control/shutdown purposes. The MRR-HP features: 1- Fast neutron spectrum. 2- Compact (1 m diameter, 1.73 m length, mass: 1.982 tons), which permits a high degree of portability and establishment in small facilities. 3- Passive cooling. 4- Operating without refueling/maintenance for ~12.5 years. 5- High-Assay-Low-Enriched-Uranium = 19.75%. 6- Neutron flux (). 7- Inherently safe. Based on the obtained results of the neutron flux and spectrum, the MRR-HP is a multi-purpose reactor that has the potential to perform: Boron Neutron Capture Therapy, Neutrons activation analysis, Testing and Calibration, Transmutation, Neutron Imaging, Education and Training, Prompt Gamma Neutrons activation analysis, Isotope Production, Fast Shielding.

Investigation of Optical Coupling in Microwave Kinetic Inductance Detectors Using Superconducting Reflective Plates

To improve the optical coupling in microwave kinetic inductance detectors (MKIDs), we investigate the use of a reflective plate beneath the meandered absorber. We designed, fabricated and characterized high-Q factors TiN-based MKIDs on sapphire operating at optical wavelengths with a Au/Nb reflective thin bilayer below the meander. The reflector is set at a quarter-wave distance from the meander using a transparent Al2O3 dielectric layer to reach the peak photon absorption. We expect the plate to recover undetected photons by reflecting them back onto the absorber.

Megathrust reflectivity reveals the updip limit of the 2014 Iquique earthquake rupture

The updip limit of seismic rupture during a megathrust earthquake exerts a major control on the size of the resulting tsunami. Offshore Northern Chile, the 2014 Mw 8.1 Iquique earthquake ruptured the plate boundary between 19.5° and 21°S. Rupture terminated under the mid-continental slope and did not propagate updip to the trench. Here, we use state-of-the-art seismic reflection data to investigate the tectonic setting associated with the apparent updip arrest of rupture propagation at 15 km depth during the Iquique earthquake. We document a spatial correspondence between the rupture area and the seismic reflectivity of the plate boundary. North and updip of the rupture area, a coherent, highly reflective plate boundary indicates excess fluid pressure, which may prevent the accumulation of elastic strain. In contrast, the rupture area is characterized by the absence of plate boundary reflectivity, which suggests low fluid pressure that results in stress accumulation and thus controls the extent of earthquake rupture. Generalizing these results, seismic reflection data can provide insights into the physical state of the shallow plate boundary and help to assess the potential for future shallow rupture in the absence of direct measurements of interplate deformation from most outermost forearc slopes.

Gluteus Maximus Transfer following Total Hip Arthroplasty Does Not Improve Abductor Moment: A Case-Control Gait Analysis Study of 15 Patients with Gluteus Medius Disruption.

Gluteus maximus flap transfer (GMT) is a surgical technique used to improve gait kinematics and kinetics, as well as to reduce and ameliorate the functional outcome in patients with hip abductor deficiency following total hip arthroplasty (THA). The purpose of this observational study was to evaluate the gait pre- and postoperatively and examine whether GMT increases the abduction moment. Materials and Methods: A gait analysis based on reflective markers and force plates was performed in 15 patients who underwent GMT and were examined using an optical tracking system before and at a minimum of 13 months after the operation. The median follow-up time was 24 (13–60) months. The primary outcome was hip abduction moment (Nm/kg) during gait. The control group consisted of 15 female subjects without any gait pathology. Results: The mean adduction moment was significantly higher compared with controls before the operation (p = 0.02), but this did not apply to the abduction moment (p = 0.60). At the group level, the abduction moment did not improve postoperatively (p = 0.30). Only six of fifteen patients slightly improved their hip abduction moment postoperatively. However, speed (0.74 to 0.80 m/s) and cadence (94 to 105 steps/min) were improved (p < 0.03). Discussion: The results of this study showed no improvement in the hip abduction moment after GMT surgery. In our experience, abduction deficiency following primary THA is still a difficult and unsolved problem.

Research on dual antenna design of RFID sensor

With the popularization and application of RFID sensors, the energy supply of internal circuits is a key problem. When multiple monitoring quantities are involved, the traditional energy extraction method of RFID sensors often leads to insufficient energy. Therefore, this paper designs an RFID sensor integrating acceleration and temperature sensing parameters, and proposes a cross placed dual antenna scheme. In order to increase the concentration of antenna radiation energy, a metal reflective aluminum plate is added. Through experimental tests, it is proved that the scheme can well optimize the radiation direction and performance of the antenna.

Thermo-electro-hydraulic analysis of jet impingement bifacial photovoltaic thermal (JIBPVT) solar air collector

The effects of impinging air jet on the thermo-electro-hydraulic performance of a bifacial PVT with different packing factors are entirely unclear. Here, we have proposed a dual-functional jet plate reflectors are introduced to induce jet air cooling and increase the light absorption at the rear part of the bifacial PV module. The effects of jet plate reflectors with different configurations on the system's performance are investigated and studied. The simulation results were verified and validated with the experimental findings. Increasing the distance between jet holes reduces the interference and enhances the heat transfer, which led to higher friction and greater pumping power. Net energy gain is the key to calculate hydraulic efficiency, by subtracting the pumping power from the energy output. Therefore, the system's best performance can be explained by the lowest Re to generate max efficiencies. Jet impingement bifacial photovoltaic thermal (JIBPVT) with 36 jet-holes has the greatest jet spacing between the jet holes and optimum performance. The maximum thermal energy gain and electrical energy produced were achieved at lower critical values of Re, which are 9929 and 5667, respectively. JIBPVT has the optimum thermal, electro, and thermo-electro-hydraulic efficiencies, with 57.3%, 10.36%, and 83.93%, respectively.

A combined thermal and electrical performance evaluation of low concentration photovoltaic systems

Due to the expectations of improving the overall efficiency of photovoltaic installation, the increase solar irradiation that could be converted into electricity should be considered as an alternative solution for existing PV technologies. Low-concentration photovoltaic systems such as reflective surfaces or Fresnel micro lens plates were chosen for this study because they were economically justified and easy to install and maintain. The low concentration systems were studied theoretically and experimentally under sunny and cloudy weather conditions. After the initial optimization of the system geometry and construction, both electrical and thermal performances were evaluated and compared with a reference PV panel. In addition, the effect of additional irradiation as well as panel temperature was studied for a specific period using thermography and digital image techniques. It was revealed that the highest improvement in energy performance was achieved by the panel with reflective surfaces, while the Fresnel plate considered here slightly decreased this performance in comparison with the reference case. The consideration ends with an economic analysis of both systems in the case of free-standing PV installation and a list of recommendations are presented, based on the empirical results. The highest improvement of energy performance can be achieved by the implementation of reflective surfaces, about 20% of the average daily global efficiency, and 15% on electrical production. In the case of the Fresnel micro lens, a decrease in both global efficiency and electricity production is observed, 8% and 21%, respectively. Regarding the temperature of PV panels, significant overheating was not registered; about 45–55 °C for the entire experimental test.

Thermally switchable and tunable metasurface with polarization independence based on VO2 phase transition

In this paper, a thermally tunable metasurface (TTMS) based on phase material vanadium dioxide (VO2) is designed and demonstrated, which consists of VO2 patterns, metallic resonators, dielectric substrates, and a gold reflective plate. Exhibiting ultra-broadband absorption from 4.72 THz to 9.88 THz with absorptivity exceeding 90% above the phase change temperature of VO2 and realizing single-band absorption when the VO2 resonators are in the insulator phase, the proposed TTMS possesses excellent low radar cross-section (RCS) performance as well as can be tailored by controlling the temperature of the phase material VO2. Furthermore, the devised TTMS is polarization-insensitive and can work well under a wide range of incident angles. The demonstrated tunable metasurface promises potential applications in the terahertz regime, such as modulating, radar stealth, and thermal detection.

Design and Construction Solar Oven Sterilizer

Researchers are seeking to help doctors, especially surgeons, in remote areas overcome the problem of ‎diseases transmission by using non-sterile surgical equipment. This study presented a design and ‎model of a low-cost solar sterilizer to sterilize surgical equipment with hot dry air. Sterilization with dry hot air requires a temperature‎‎160℃ for 60 minutes. The design includes a stainless steel box with dimensions of 60 cm×30 cm×12 cm in which the surgical equipment is placed. This box is placed inside a chamber with insulated ‎walls, except for the front and top. The front and top are a layer of tempered thermal glass. This chamber ‎rests on an iron base that rotates around an axis in its center to follow the sun from east to west. ‎Placed reflective sheets arranged in a cone shape around the surgical equipment box to increase the ‎thermal enablement of the box. The system was tested in several variants. With and without surgical equipment and with and without reflective plates. The system achieved 160℃ hot air in 121 minutes. ‎This period increased by 23.9% when surgical equipment weighing 1.2 kg was placed. The ‎presence of reflective plates reduced the time required to achieve the required heat by 9%.

Full-range birefringence control with piezoelectric MEMS-based metasurfaces

Dynamic polarization control is crucial for emerging highly integrated photonic systems with diverse metasurfaces being explored for its realization, but efficient, fast, and broadband operation remains a cumbersome challenge. While efficient optical metasurfaces (OMSs) involving liquid crystals suffer from inherently slow responses, other OMS realizations are limited either in the operating wavelength range (due to resonances involved) or in the range of birefringence tuning. Capitalizing on our development of piezoelectric micro-electro-mechanical system (MEMS) based dynamic OMSs, we demonstrate reflective MEMS-OMS dynamic wave plates (DWPs) with high polarization conversion efficiencies (∼75%), broadband operation (∼100 nm near the operating wavelength of 800 nm), fast responses (<0.4 milliseconds) and full-range birefringence control that enables completely encircling the Poincaré sphere along trajectories determined by the incident light polarization and DWP orientation. Demonstrated complete electrical control over light polarization opens new avenues in further integration and miniaturization of optical networks and systems.

A High Gain Antenna with DGS for Sub-6 GHz 5G Communications

This paper introduces the design of a high-gain wideband microstrip patch antenna for sub-6 GHz 5G communication. The proposed antenna integrates a novel defected ground structure (DGS) for achieving the wide bandwidth. The ground plane uses a triangular strip inserted into the ground plane to improve the performance of the antenna. It also uses the reflective plate to concentrate the side lobes and minimise the production of the back lobe, thereby boosting the main lobe of the radiated signal and thus increasing the gain of the proposed antenna. The proposed antenna uses the FR-4 epoxy substrate with an inset feed technique in its design. The simulation and optimisation of the proposed antenna were carried out with CST Microwave Studio Suite. The antenna design is compact with a dimension of 28:03 23:455:35mm3 and a maximum gain and directivity of 6.21 dB and 7.56 dB respectively, with a radiation efficiency of about 80%. The proposed antenna operates from 4.921 GHz to 5.784 GHz, which covers the 4.9 GHz-5.8 GHz of the sub-6 GHz 5G communications spectrum. Fabricated and measured result of the antenna confirm simulated results.

New proposed ITER divertor design using carbon insert on tungsten to mitigate ELMs and secondary radiation effects on nearby components

Building a successful device for the magnetic fusion energy production is a great challenge. ITER is an international project of the tokamak based magnetic fusion design being developed for the demonstration of the feasibility of thermonuclear technologies for future realization of successful commercial fusion energy. A key obstacle to a successful magnetic fusion energy production is however, the performance during abnormal events including plasma disruptions and edge-localized modes (ELMs). A credible reactor design must tolerate at least a few of these transient events without serious consequences such as melting of the structure. This paper investigates and compares the performance of the current ITER tokamak design during two types of transient events, i.e., ELMs occurring at normal operation and disruptions during abnormal operation. We simulated the divertor components response using our integrated 3D HEIGHTS package. The simulations include self-consistent modeling of the interaction of the released core plasma particles with the initial solid divertor material, energy deposition processes, vaporization of divertor material, secondary plasma formation and MHD evolution, incident core particles collisions and scattering from this dense secondary plasma, photon radiation of secondary plasma, and the resulting heat loads on nearby components. Our simulations showed that using a small carbon insert around the strike point can significantly reduce the overall expected damage on the tungsten dome structure, reflector plates, and prevent tungsten vaporization and its potential core plasma contamination.

Broadband and deep subwavelength acoustic antenna based on Fabry-Perot-like acoustic grating resonators

Acoustic grating metamaterials (AGMs) with exotic enhancement property and remarkable directional response are promising candidates to advance the metamaterial-based acoustic sensing. In this paper, a graded reflection AGM (GRAGM) is proposed to broaden the working bandwidth and reduce the device volume. In contrast with conventional periodic AGM, GRAGM with graded slit width can be viewed as a series of combined Fabry-Perot-like (FP-like) resonators. As a result, the working band is broadened twice by combining multiple resonant bands. The added reflection plate is capable of reducing the working frequency of GRAGM by manipulating the reflection phase at the boundaries with the maximum variation over than 280 Hz, which enables the GRAGM to work in a deep subwavelength scale. Moreover, the strong directional response of the GRAGM is able to localize sound sources. These exotic properties promise a number of potential applications, such as sound source localization, condition monitoring, and remote whispering.

Synchronous measurement method of a multi-angle scattered light field.

A synchronous multi-angle scattered light field measurement system is constructed in this study to overcome issues with current systems in the field of multi-angle remote sensing. A mathematical model of the scattered light field measurement was established. An off-axis catadioptric optical system was designed to satisfy hemispheric spatial scattered light field measurements in a zenith angle range of 68°. The off-axis calibration model was established, and the spatial relationship was calibrated. The measurement accuracy was calibrated via an integrating sphere light source, and the maximum measurement relative error was -3.71%. The scattered light field of the reference diffuse reflective target plate Labsphere Permaflect-50 and 304 stainless steel was simulated under an incident light irradiation range within the zenith angle of -23.5∘ to +23.5∘, and synchronous measurement of the multi-angle scattered light field of the sample was realized. The measurement system could provide technical support for building the complex model of multi-angle reflection/radiation from the earth's surface, multi-angle sensor radiation calibration, and improvement of the physical parameter inversion accuracy of observation targets.

Pengaruh Material Reflektor Terhadap Kinerja Kompor Energi Surya

The use of solar energy in Indonesia is the right choice as an alternative energy for energy needs in industry or to meet daily energy needs in households. To utilize solar energy for cooking purposes, a solar cooker can be used. Factors that affect the performance of this solar cooker in addition to the length of time it shines and the intensity of thermal radiation from the sun are the reflexivity of the collector material, the surface area of ​​the collector, the geometric shape and location of the focal point of the collector, the normal direction of the collector surface to the incoming sunlight, and the amount of heat loss to the surroundings. The materials used as reflectors in the research on this solar cooker are zinc (aluminum and galvanized) AL-Zn and black paint back ground mirror glass. This material is re-glued on top of a ready-made parabolic dish from the market. Then look for the focal point that corresponds to the diameter of the parabola. From the results of the study, it can be concluded that the back ground mirror glass material with black paint is better to use than the AL-Zn zinc plate if it is used as a raw material for the surface material (reflector) of solar cooker. Likewise, the efficiency of the solar oven in terms of the amount of heat that is converted into energy for heating the pot is better for a solar oven than a reflector with black paint back ground mirror glass material. And the efficiency of the solar cooker from the black paint back ground mirror on the first day is 16.4% to 25.7% on the second day, while the efficiency of the solar cooker from the AL-Zn zinc plate on the first day is 16.4% to second day 22.8%. The emissivity of the solar stove with AL-Zn zinc plate reflector on the first day was 0.02906 and on the second day 0.02892, while the emissivity of the solar cooker with black paint back ground mirror reflector on the first day was 0.01812 and the second day was 0 0.02544.

Versatile polarization manipulation in vanadium dioxide-integrated terahertz metamaterial.

Broadband and switchable versatile polarization metamaterial is crucial in the applications of imaging, sensing and communication, especially in the terahertz frequency. Here, we investigated versatile polarization manipulation in a hybrid terahertz metamaterial with bilayer rectangular rods and a complementary vanadium dioxide (VO2) layer. The VO2 phase transition enables a flexible switching from dual-band asymmetric transmission to dual-band reflective half-wave plate. The full width half maximum (FWHM) bandwidths of dual-band asymmetric transmission are 0.77 and 0.21 THz, respectively. The polarization conversion ratio (PCR) of the reflective metamaterial is over 0.9 in the frequency ranges of 1.01-1.17 THz and 1.47-1.95 THz. Angular dependences of multiple polarization properties are studied. The proposed switchable polarization metamaterial is important to the development of multifunctional polarization devices and multichannel polarization detection.

Point Cloud Intensity Correction for 2D LiDAR Mobile Laser Scanning

The acquisition of point cloud data by mobile laser scanning (MLS) includes not only the information about the 3D geometry of the object but also the intensity from the scanned object. However, due to the influence of various factors, there is a large deviation between the intensity and the spectral reflection characteristics of the scanned object. Intensity correction should be carried out before this method is applied to object recognition. A new point cloud intensity correction method for 2D MLS that was developed by combining theoretical derivation with empirical correction is proposed in this paper. First, based on the LiDAR formula, the main factors influencing MLS intensity are investigated, and a distance piecewise polynomial and an incident angle cosine polynomial are adopted to obtain the intensity correction model of UTM-30LX 2D LiDAR on a diffuse reflector plate. Second, according to the scan pattern, a 2D scan grid is constructed to organize the MLS intensity, and a new method of spherical neighborhood search fitting plane is proposed to accurately calculate the cosine of the incident angle. Finally, the obtained intensity correction model is utilized to correct the MLS intensity of a wall. Two groups of verification experiments are carried out on single sites and multiple sites to test the effect of the intensity correction model. Overall, the improvements in intensity consistency range from 70% to 92.7% after correction within the tested ranges of distance and incident angles [0.52 m-5.34 m, 0°-74°]. The results indicate that the proposed intensity correction model yields highly accurate fitting and can effectively remove the deviation in MLS intensity caused by the distance and incident angle.

Development of an aerial ultrasonic sound source with a truncated cone-shaped reflective plate on a circular transverse vibrating plate

Development of an aerial ultrasonic sound source with a truncated cone-shaped reflective plate on a circular transverse vibrating plate

Determination of the heat transfer coefficient of a rotary film evaporator with a heating film-forming element

A model of a rotary film evaporator with a film-forming element with a reflective heated surface has been developed. This will allow stabilizing the hydraulic movement of the cut wave flow due to the reflective surface of the geometric shape for the forced direction of the cut raw material to the heating surface. Autonomous heating of the reflective surface additionally provides a temperature effect in the conditions of movement of particles of raw materials after cutting. The analysis of the experimental and theoretical parameters of heat transfer made it possible to substantiate the criterion equation for determining the heat transfer coefficient of an evaporator with the proposed film-forming element and a reflective heated surface for calculating the coefficient from the working surface to the raw material. The resulting equation takes into account the influence of the vertical component of the motion of the raw material film, centrifugal movement during the rotation of the film-forming element, mixing of the boiling film of the raw material with steam bubbles, and the geometric characteristics of the film-forming blade on the hydrodynamic flow of the raw material. The calculation of the rotary-film evaporator was carried out using the criterion equation and the obtained useful heat exchange surface – 0.75 m2. The specific metal consumption in a rotary film evaporator with a film-forming element having a reflective surface is 57 kg/m2, compared to the vacuum evaporator traditionally used in canning industries (410 kg/m2), which is 7.1 times less. The duration of the temperature effect on the raw material is also reduced: a rotary film evaporator – 200 s and 3600 s in a traditional apparatus. The data obtained will be useful for the design of rotary-film devices of different geometric parameters using articulated blades with a reflective plate.

Design and development of a low-cost system to convert solar thermal energy into electricity for households in South Africa using solar concentrators

South Africa is, due its specific latitude location in the southern hemisphere, exposed to high solar irradiation levels. Black thermal absorbers have a high absorbance for solar incident radiation, while commercial photovoltaic technology only converts about 10% of energy available in the solar spectrum. In this article, low-cost Peltier conversion cells, that are normally used for cooling purposes, and that are freely available in supply stores in South Africa, were identified as suitable conversion cells for converting thermal energy into electricity. Two prototypes of thermal-to-electricity energy conversion systems were subsequently designed and developed. Particularly, advanced pulse mode DC- to- DC conversion technology, a special electronic control system, was developed, that could extract high amounts of electrical energy from the cells and could store the energy in standard storage batteries. A 3 W and a 30 W output continuous conversion capacity system were developed. A power conversion of up to 2 W capacity per individual cell was achieved. The systems used no movable parts, and the lifespan of the systems is projected to be at least twenty years. Cost and viability analyses of the systems were performed and the results were compared to existing solar photovoltaic energy conversion systems. Combining the 30 W capacity system with a black body and reflector plate absorber system revealed a cost structure of only ZAR 0.8 per kWh, as compared with a derived ZAR 3 per kWh for a combined photovoltaic and solar geyser combination, as calculated for a ten-year term. The technology as developed is suitable to be incorporated in South African households and rural Africa applications.