Rectangular Type Research Articles

Microstrip Patch Antenna Design for 5G and Beyond Wireless Communication Systems

This paper gives a theoretical evaluation on how feeder lengths are appropriate for distinct conductor materials using rectangular microstrip patch antenna shape with the help of finite integration techniques (FIT). In this study, the ground surface width is 5.6mm and the ground surface length is 4.65 mm for the rectangular microstrip patch antenna. The length of the patch is 3.44 mm while the patch width is 4.40 mm. The substrate thickness is at 0.20 mm, the patch thickness is 0.035 mm the additional inner feed length is 1.05 mm and the microstrip line feed width is 0.6 mm. Antenna of rectangular microstrip patch type has been designed to work in the 20 – 36 frequency band and working frequency of the proposed antenna is 28 GHz. Compared to the use of a single conductor on the surface of the designed patch antenna, three different conductor materials-copper, gold, and aluminum-were applied to the patch surface of the antenna. The return loss (S11), voltage standing wave ratio (VSWR), bandwidth (BW), directivity and gain of the microstrip antenna parameters are studied using finite integration method Computer Simulation Technology (CST) based on nine different feed lengths in microstrip antenna design. When analyzing the feature of the simulation, the optimal S11 can be observed at the 28 resonant frequencies in the copper conductor. According to the analysis results, for copper conductor the best S11 was obtained at a resonant frequency of 28.03 GHz. The value of S11 is -31.19 dB and the BW value is 968 MHz. For the gold conductor the high return loss is achieved using the at the resonated frequency of 28.01 GHz. S11 value is -32 dB and the BW value is 972 MHz Aluminum conductor has the highest value of S11 with a resonant frequency of 28.01 GHz as shown in -33.29 dB and BW value is 976 MHz. Unsurprisingly, the characterization of the conductor deposition on each structure shows that aluminum conductor yielded the best S11 among all the conductor types. The VSWR is equal to 1.05 for copper conductor at resonant frequency of 28.03 GHz, 1.05 at gold conductor at a resonant frequency of 28.01 and 1.04 for aluminum conductor at a resonant frequency of 28.01 GHz. The maximum directivity values that have been attained in the three-dimensional (3D) representation of the copper conductor, gold and aluminum conductor antennas are nearly 6.99 dBi, respectively. The maximum values of the gain are obtained for the 3D representation of copper, gold and aluminum conductor antennas are 6.61, 6.60 and 6.58 dBi, respectively.

VIKTORIA experiments in the frame of R&D project on sump filtration during a loss of coolant accident

During a Loss of Coolant Accident (LOCA), in PWR’s, water is injected by the Emergency Core Cooling System (ECCS) to ensure the long-term core coolability and by the Containment Spray System (CSS) to remove residual heat and to maintain containment integrity. After the drainage of the Refueling Water Storage Tank (RWST), water is taken from sumps in the lower part of the reactor building. A filtering system is implemented to collect debris produced by the pipe break as well as other latent materials, such as fiberglass, paint and concrete particles, and to minimize the amount of debris entering in the ECCS and CSS systems. IRSN has launched an experimental R&D project investigating the clogging of sump filters by integral tests performed in the VIKTORIA loop. The main objectives are to investigate the head loss of the filter (physical and chemical clogging) for prototypic upstream debris source term in relevant thermal hydraulic conditions (water temperature and flow velocity on the filter surface) in compliance with the temperature profile and the chemistry of the water in sumps during a LOCA transient. For that, the VIKTORIA loop was equipped successively with two types of 2 m2 filters used in 900MWe NPP’s. The tests highlight the settling of the largest particles (concrete, painted chips) and part of the fibers; the transport of debris (roughly 55 to 65 % of the injected debris source term) leads to the physical clogging of the filter. The debris carried to the filter generate at 80 °C (with chemistry) a very quick increase of the pressure drop across the filter (≈7 kPa) that could be due to rapid chemical effects further to fibers corrosion. At the end of the 80 °C plateau, a pressure drop increase was observed due to the temperature decrease in agreement with the water viscosity evolution. The two types of filters (rectangular pockets or planar types) behave very differently with rather low head losses for the second type; ≈1.5 kPa. Nevertheless, downstream debris source term appears to be more significant with the planar filter (compared to the filter with pockets) during the first hour of injection before the fibrous debris bed formation. We have also observed a more stabilized “cake”, during the (7 days) medium term evolution compared to that for rectangular pockets filter due to motion of debris inside pockets. The recent experiments performed with less amount of fibers (by replacement of part of fibrous materials by RMI metallic insulation) led to significantly reduce the head loss without any consequences on the downstream behavior.

Structural assumption on design of rounded rectangular bellows under pressure

Bellows is a flexible component whose volume can be changed by compression or expansion under pressure. Rounded rectangular type bellows is most applied where the internal space of application is strict. The Expansion Joint Manufacturers Association (EJMA) code is world-recognized code for design by formulas method. However, the calculation formulas of stress and deformation in EJMA code does not consider the shape of corner. Therefore, this study proposed a structural assumption of curved beam model to calculate the stress and deformation for rounded rectangular bellows under pressure load by formula calculation method. A parametric study by means of finite element analysis (FEA) was performed to assess the impact of different structural parameters and the applicable scope was investigated. The experimental and numerical results showed that the proposed method can obtain a suitable precision and safe result when ratio of wave height to corner radius is lower than 35 % and the ratio of length of short side length to corner radius is in range 5–20. This study will enrich existing bellows design code and help industry designers to accelerate the optimization iteration in preliminary design stage instead of FEA.

Improvement of beam quality of high-power edge-emitting lasers using inhomogeneous waveguides

Inhomogeneous waveguides with corrugations have the potential to increase the fundamental mode brightness of edge-emitting lasers as compared to straight waveguides. The corrugations partly suppress the high-order lateral modes of the lasers. The impact of the shape and size of rectangular and triangular types of corrugations on the lasing performance is compared for the first time, and an optimized design is presented. This concept of introducing corrugations is investigated for conventional edge-emitting lasers, as well as high-brightness vertical broad-area edge-emitting (HiBBEE) lasers. The corrugated HiBBEE lasers provide an almost two times larger brightness than the reference lasers.

EXPERIMENTAL STUDY OF DELAYING THE STALL OF THE NACA 0020 AIRFOIL USING A SYNTHETIC JET ACTUATOR ARRAY WITH DIFFERENT ORIFICE GEOMETRIES

An experimental study on the effect of active flow control using a synthetic jet mechanism on stall delay for the NACA 0020 airfoil is conducted. The experiments are carried out at an open-suction type wind tunnel at Reynolds number 5x104. In the presented experimental study, aerodynamic force measurements of the airfoil with having different orifice geometries (cylindrical, rectangular, sinusoidal, v-type, inclined rectangular) are examined by using a speaker type actuator in synthetic jet mechanism. It is observed that all different orifice geometries are effective in delaying the stall angle of NACA 0020 airfoil. However, it is observed that the inclined rectangular type of synthetic jet geometry is the most advantageous in delaying the stall of the airfoil. The effects of geometric parameters of the actuator on lift and drag coefficient of the NACA0020 airfoil are investigated. Experimental results show that among the all-orifice geometries the rectangular orifice geometry is the most effective in increasing lift coefficient of the airfoil. It is observed that there is a maximum decrease in drag at 10⁰ where the stall occurs. In addition, the decrease in drag is observed after 10 in rectangular, v-type and inclined rectangular orifice geometries.

Analysis of enhanced thermal transmission mechanism with microstructures by field synergy theory

This study numerically examines the impact of oblique ribs and staggered herringbone microstructures on the heat transfer performance of microchannels. The results indicate that the Nux values of the oblique rib (Type A) and staggered herringbone (Type B) microchannels exhibit significantly higher performance compared to smooth rectangular (Type C) microchannels. The oblique ribs and staggered herringbone microstructures improve heat transfer efficiency along the flowing direction, leading to an evident increase followed by horizontal fluctuations in Nux . In contrast, the Nux of Type C without microstructures decreases significantly at the inlet and subsequently remains relatively constant. The bottom temperature Tw of Type A and B are lower than the temperature of Type C. The results of field cooperation analysis indicate that the synergistic fields of the oblique ribs microchannels primarily exist along both sidewalls, while they are present at the fluid center for the staggered herringbone microchannels. Type A exhibits a slightly stronger heat transfer effect despite having a smaller synergistic area compared to Type B.

Removal of chemicals from effluent using photobioreactor technology to improve environmental and health impacts

Abstract The treatment of industrial waste water using cyanobacteria in photobioreactor for the removal of sulphide, COD and phenol. The microorganisms were collected from the effluent treatment plant of a petroleum refinery and a biofilm was developed in nutrient medium. The reactor was fed with cyanobacteria. After biofilm formation and acclimatization, the same procedure was followed for 16 days in a rectangular tray type photo bioreactor for the treatment of industrial waste water. From continuous mode of operation, it was found that the phototrophic microorganisms can degrade the pollutants present in industrial waste water. The removal efficiency of hardness 75 %, sulphide 95.8 %, COD 98.7 %, phenol 99.9 % and nitrate 83.7 % was studied. The present works shows that it is feasible to use cyanobacteria in a photo bioreactor for the treatment of industrial waste water.

Numerical study on discharge capacity of piano key side weir with various ratios of the crest length to the width

Abstract A side or lateral weir can be defined as a longitudinal weir put in parallel to the main flow direction. A piano key side weir (PKSW) is one of the various side weirs used to control flow level, flow diversion, and flood harm prevention in dams and hydraulic systems. A side weir aims to keep the water level in the main channel at a specific level by discharging the overflow water into a side channel. The discharge coefficient of the PKSW was covered in this study by numerical modeling of a rectangular PKSW type B with various ratios of the crest length to the width in a straight channel. Results showed that the discharge coefficient of the PKSW was more affected by the L/W parameter when the other parameters were constant. It was noted that the PKSW discharge coefficient for L/W equal to 6 demonstrated a significantly higher level of performance and also found that increasing the upstream head above the side weir crest (h a/P) negatively affected the coefficient of discharge. It was concluded that a high capacity of the discharge coefficient required the (h a/P) ratio to be smaller than 0.75 or within the range (0.3 ≤ h a/P < 0.75).

Bragg Grating Cavity Design Using Bragg Gratings

The aim of the experiment is to design Bragg Grating Cavity design (to show Fabry Perot effects) for High Quality Factor. The basic Bragg Grating design used in this project consists of two identical Bragg Gratings and a cavity between the two Gratings. Bragg devices are first simulated using Transfer Matrix Model (TMM) on MATLAB. Parameters like Number of Grating Periods, Cavity Length and Type of Grating are varied to note the effect on Quality Factor. 7 Bragg devices are then designed using KLayout, visualized using Lumerical Interconnect and compared to Matlab TMM model. Simulated results are compared to Measured results using MATLAB and the differences between measurement data and simulated data are discussed. Out of the several implemented designs, the rectangular grating type design with Grating periods of 195, cavity length of 54.6μm and corrugation width 0.045μm resulted in the highest experimental Quality Factor.

Heat Transfer Augmentation in Fin and Tube Heat Exchanger Embedded with Vortex Generators

The aim of this study is to investigate experimentally turbulent flow around tube by using multi–shapes of winglet vortex generators mounted behind the tube at different angles of attack, in order to investigate the effect of winglet on heat transfer and pressure drop of fin and tube heat exchanger placed inside a rectangular duct with Reynolds numbers (Re) ranging from (19000) to (49000). Fin-and-tube heat exchangers are frequently employed in a variety of industries, including power systems and air conditioning. The heating element inside the tube receives a power source ranging from (10W) to (40W). In these studies, vortex generators of the triangular and rectangular types are installed at various angles of attack (45° and 60°) on the fin surface behind the tube. The findings demonstrate that depending on the form and angle of attack of the winglets, utilizing winglet pairs has an impact on the heat transfer coefficient and friction factor relative to other designs. With increasing angle of attack, the friction factor and heat transfer coefficient rise. The optimal design for improving heat transfer is the rectangular type vortex generator, whereas the triangular type produces the least amount of heat transfer. The rectangular style of duct has the greatest pressure drop. For rectangular and triangular heat exchangers, respectively, the average Nusselt number is increased by 19% and 12%. The average Nusselt number of a fin and tube heat exchanger is increased by (16.7-17.8%) % for the rectangular type and by (9.3-10.6%) % for the triangular type at an angle of attack (β=60°) compared to (without winglet) case for Reynolds number ranging between (19000-49000), where the triangle type gives the least amount of heat transfer compared to other shapes.

Higher-Frequency Permeability Measurement by Harmonic Resonance Cavity Perturbation Method

A new combination of electric field antenna and coupling hole plates are introduced to extend the measurable frequency range of rectangular waveguide type harmonic resonator to evaluate complex relative permeability of magnetic composites by perturbation method from 18 GHz to 38 GHz (K/Ka-band). The noise suppression performance parameter ωμ”=2πfμ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ” [kΩ/m] is useful to estimate the performance of magnetic powder composite sheets especially beyond 10 GHz range where relative permeability is as small as 0-2. The ωμ” exhibited the maximum of 166 kΩ/m at 27 GHz for a carbonyl iron powder composite sheet, and as high as 510 at 38 GHz for Sendust sheet. These values meet ωμ”≥100 kΩ/m criteria that some commercially available noise suppression sheets exhibit in their recommended frequency range. These performance match Sub-6 GHz band and 28 GHz band used for 5G telecommunication equipment.

Development of micromodels of traffic flows, taking into account environmental factors

The article considers an actual problem of organizing a safe and sustainable urban transport system. We have examined the existing positive global experience in both infrastructural and managerial decisions. Then to assess possible solutions at the stage of infrastructure design, we have developed the simulation micromodels of transport network sections of the medium-sized city (Naberezhnye Chelny) with a rectangular building type. The models make it possible to determine the optimal parameters of the traffic flow, under which pollutant emissions from cars would not lead to high concentrations of pollutants. Also, the model allows to obtain the calculated values of the volume of emissions of pollutants and the parameters of the traffic flow (speed, time of passage of the section, etc.). On specific examples, the proposed method’s effectiveness is shown. Case studies of cities of different sizes and layouts are implementation examples and possible uses proposed by the models. This study has shown the rationality of the suggested solution at the stage of assessing infrastructure projects and choosing the best option for sustainable transport development. The proposed research method is universal and can be applied in any city.

Development of energy efficient design proposals for air conditioned mosques: Temperate humid climate case

Mosques, which are types of religious buildings, are large buildings where many people pray at the same time. The diversity of the user type and density and the variability of the usage schedule make it difficult to establish the homogeneous thermal comfort of these large-volume public buildings. At the same time, the energy consumption in the buildings should be minimal in nowadays when the conventional energy sources decrease. The aim of this study is to evaluate created design strategies for designers and users in order to minimize energy consumption by determining the passive design criteria and choosing the type of air conditioning equipment while providing an acceptable thermal comfort level in mosques. According to the method created for the aim, the scenarios of mosques were compared in terms of thermal comfort and energy consumption in the temperate humid climate conditions. This method includes the analysis of scenarios created from the change of design parameters of mosques (plan, size, roof type of the mosques) with a simulation software which was validated with actual utility data. The suggestions were presented for the selection and design of the mechanical system as a result of the implementation of the created method. When the design scenarios of mosques are compared, the air conditioning of the indoor with radiant method consumed less energy than HVAC equipment with fan system. In accordance with the plan schemes (square, rectangle, circular), the least energy consumption per unit area was in the circular plan scheme and hemispherical design. Compared to the roof types (single dome, multi dome, pyramidal roof, flat roof), the most energy consumption per unit area was generally in the multi dome design. According to the average energy consumption values of the HVAC systems, there was 23 % less energy consumption in the flat plan type (105.06 kWh/m2) compared to the rectangular plan type (129.2 kWh/m2). In the intermittent use schedule of the HVAC system, 8 % more energy was consumed than in the continuous use schedule. According to the air changes per hour in the mosques, there was 5.93 % more energy consumption in 2 ach conditions compared to 0.5 ach conditions.

Effectiveness of a tubular heat exchanger and a novel perforated rectangular flow-deflector type baffle plate with opposing orientation

Purpose The purpose of this experimental research was to examine a novel axial heat exchanger featuring swirling air movement over heated tubes. This apparatus is designed with perforated circular baffle plates complemented by rectangular air deflectors operating at different inclination angles. The tubes were arranged in a consistent layout parallel to the longitudinal airflow. The deflector’s heightened air-side turbulence initiates the frenzied motion, escalating the surface heat transfer rate. Design/methodology/approach The tubes maintained a constant heat flux condition over the surface. In each baffle plate, eight deflectors with identical inclination angles were devised in a reverse position, forming a rotation of air inside a circular duct that held tubes (carrying hot water) which elevated air-side turbulence, thereby enhancing the rate of heat transference on the surface. The baffle plates were equally situated from each other at changing pitch ratios. The Reynolds quantity was preserved in the scope of 16,000–30,000. The performance of the heat exchanger considering pitch ratios and inclination angles was examined. Findings The research indicates that when examined under similar conditions, an exchanger with a deflector baffle plate shows a strong dependence on the pitch ratio and inclination angle with a mean rise of 0.19 times in thermal enhancement factor at an inclination angle of 30° and a pitch ratio of 1.2 contrasted with an exchanger with segmental baffle plates. Originality/value The result shows the dependence of pitch ratio, Reynolds number and inclination on the heat transfer and friction factor rate.

Exact approaches for the unconstrained two-dimensional cutting problem with defects

This paper studies the unconstrained two-dimensional cutting problem with defects, which requires cutting a set of rectangular item types from a rectangular sheet with defects. The available number of each type is not limited. Two versions of the problem are studied, based on whether the guillotine cut constraint is required. Due to equipment limitations, the guillotine cutting restrictions are essential in specific industries, requiring cutting from one side to the other with each cut and splitting the sheet into two separate sheets. An integer model is proposed for the non-guillotine cut version, and an exact dynamic programming (DP) approach is proposed for the guillotine cut version. To reduce the number of vertical and horizontal positions, we extend the normal patterns, raster points, and meet-in-the-middle patterns to consider the effect of defects. The experimental results on standard benchmarks show that the proposed model can solve most of the instances in literature in a short time. For the guillotine cut version, our approach can significantly reduce the number of cut positions and improve the efficiency of the DP approach compared to the previous exact approach that considers all possible positions. Our approach solves the large instances with more than 300 item types in a relatively short time.

The Development and Investigation of the Diffusion-Stabilizing Burner with the Niche

The article presents the results of researches of the development and field tests in bench conditions of the microdiffusion stabilizer burner device of a rectangular slot type with a niche deepening along the entire perimeter of the burner. The air passes through a rectangular slot, gaseous fuel for combustion is supplied to the recirculation zone through a system of holes in the end wall of the stabilizer. On the side of the output end of the stabilizer, there is a niche deepening. As studies have shown, the niche deepening is an additional source of stabilization and intensification of torch burning. The experimental data and calculated dependences on the stabilization of the torch in the modes of “poor” disruption are obtained. It is shown that the stable operation of the burner on the lean limit expands – the coefficient of excess air increases with an increase in the width of the stabilizer, the diameter of the gas distribution holes, the coefficient of shading of the burner and air temperature, as well as with a decrease in the speed of the air flow. The research results showed that “rich” flame failure – flame failure with a gradual increase in gas flow occurs at air excess ratios less than unity. This ensures the reliable operation of the burner at the calculated operating modes with respect to the coefficient of excess air a = 1.15 – 6.0 and the air flow speed Wp = 12.0 m/s. A dependence was obtained that determines the influence of regime and design factors on the characteristics of a rich flare failure. The sustainability of the burner operation on the rich limit increases – the coefficient of excess air decreases, with an increase in the width of the stabilizer, the shading coefficient of the burner, air temperature and a decrease in air velocity. The experimental data and calculated dependences on the length of the combustion zone in the burner device are obtained. It was established that at the calculated coefficient of excess air a = 2.0 and higher coefficients, complete combustion of fuel occurs on the length of the combustion space X = 1000 mm. The relative length of the flame decreases when the shading coefficient of the burner and the air temperature increases. Measurements of harmful nitrogen oxides showed that the maximum content of oxides is observed at the coefficient of excess air a = 1.0 and is 125 mg/m3, which is less than the limit values which allowed by regulatory documents.

Coprecipitation Methodology Synthesis of Cobalt-Oxide Nanomaterials Influenced by pH Conditions: Opportunities in Optoelectronic Applications

The cobalt oxide (Co3O4) nanomaterials were prepared by coprecipitation synthesis technique by maintaining the pH of the mother solution at 7, 8, and 9. The prepared nanomaterials were subjected to structural and optical characterizations, and the results were examined. The optical absorption spectral studies reveal that the two absorption bands indicate ligand–metal coordination. The photoluminescence spectra contain emission peak at 488 and 745 nm due to size and shape of the synthesized materials. The magnetic nature of the samples was identified from the hysteresis loop traced by vibrating sample magnetometry (VSM). The Fourier transform infrared (FT-IR) spectrum of Co3O4 nanomaterials reveals two sharp bands absorbed in 584 and 666 cm-1. This ascribes to the Co-O and O-Co-O stretching, respectively. As the pH of the solution varied from 7 to 10, the SEM image authenticates the transformation of Co3O4 nanomaterials morphology from spherical to cubic to agglomerated shape. From the UV-Vis spectra, two absorption bands around 473 nm and 762 nm are observed for the materials prepared at pH 7 and 8. But at pH 9, these two peaks were shifted towards higher wavelengths 515 nm and 777 nm. The observed ferromagnetic nature of Co3O4 nanomaterials clearly show the role of surface spins and surface morphology on the magnetic properties of Co3O4 nanomaterials. The cyclic voltammetry (CV) curves show the rectangular type of voltammogram. This is an indication of good charge propagation with the electrodes. The Nyquist plots of Co3O4 nanomaterials have a semicircle in the high frequency region and a vertical line in the low frequency region. The results suggest that Co3O4 is found to be a promising material for the fabrication of light-emitting diodes, solar cells, and optoelectronic devices.

New Approaches for Studying Conformal Embeddings and Collapsing Levels for W–Algebras

Abstract In this paper, we prove a general result saying that under certain hypothesis an embedding of an affine vertex algebra into an affine $W$–algebra is conformal if and only if their central charges coincide. This result extends our previous result obtained in the case of minimal affine $W$-algebras [ 3]. We also find a sufficient condition showing that certain conformal levels are collapsing. This new condition enables us to find some levels $k$ where $W_{k}(sl(N), x, f )$ collapses to its affine part when $f$ is of hook or rectangular type. Our methods can be applied to non-admissible levels. In particular, we prove Creutzig’s conjecture [ 18] on the conformal embedding in the hook type $W$-algebra $W_{k}(sl(n+m), x, f_{m,n})$ of its affine vertex subalgebra. Quite surprisingly, the problem of showing that certain conformal levels are not collapsing turns out to be very difficult. In the cases when $k$ is admissible and conformal, we prove that $W_{k}(sl(n+m), x, f_{m,n})$ is not collapsing. Then, by generalizing the results on semi-simplicity of conformal embeddings from [ 2], [ 5], we find many cases in which $W_{k}(sl(n+m), x, f_{m,n})$ is semi-simple as a module for its affine subalgebra at conformal level and we provide explicit decompositions.

Improvement of Plate-Fin Heat Exchanger Performance with Assistance of Various Types of Vortex Generator

A 3-dimensional incompressible laminar flow and heat-transfer in a plate-fin heat exchanger (PFHE) where investigated numerically in this article. The influence of mounting a longitudinal vortex generator (LVG) on the offset rectangular-triangular fin (ORT) in the PFHE, on thermal and hydro-dynamic fields are presented. The novelty of this study is by attaching a LVG to an offset strip fin (OSF) surface. The cases of study for the PFHE are established, by using a built-in rectangular winglet pair type RWP longitudinal vortex generator carried out and fitted on this fin to improve the convective heat transfer of the (ORT) fin while minimizing pressure loss. The upper and lower plates are exposed to constant heat flux and the working fluid is air where chosen under a laminar range of RE (600 to 1400). The laminar flow and heat-transfer are governed by continuity, momentum and energy equations. ANSYS FLUENT (2021 R1) is used to get the numerical results, based on the finite volume method. The performance of the VG is assessed for an optimum winglet attack angle (45°), as well as by modifying the geometrical size parameters, namely the height and placement (L) of the RWP LVG. The result shows that the Nusselt number reaches its optimum enhancement values by using a common flow up CFU built-in rectangular winglet pair type RWP VG with a height and entrance length of (h=1.25mm, L=0.5mm), by 22.23% as compared with base case configuration (ORT). Finally, a two more LVG are tested with the optimum conditions of the RWP, which they are a delta winglet pair (DWP) and trapezoidal winglet pair (TWP). In addition, the temperature fields for the primary and secondary flows were shown in contour and streamline diagrams

Compressive and shear behavior of cement stabilized rammed earth wallettes reinforced with coir, bamboo splints and steel bars

This paper investigates the effect of coir, bamboo and steel reinforcement on the axial and diagonal compressive strength of cement stabilized rammed earth wallettes. Two types of rammed earth wallettes were cast (rectangular and square) to study the failure pattern and effect of different height to thickness ratios on axial compressive strength. Rectangular sample type was tested only under axial compression whereas square sample type was tested under axial as well as diagonal compression. 10% cement stabilizer and 1% coir of 25 mm length were used throughout the experimental program. Experimental results reveal that addition of coir improved the compressive strength of samples by about 17.93% − 37.82% and also enhanced the failure mechanism from sudden/brittle to a gradual ductile failure. The strength of rectangular samples decreases by about 4.95% − 6.52% and deformation increases by 19.52% − 26.46% respectively when compared with square samples. The maximum compressive and shear strength was recorded with cement stabilized 4-steel coir reinforced rammed earth (CS4SCRRE) samples and the maximum deformation was observed with cement stabilized 4-bamboo coir reinforced rammed earth (CS4BCRRE) samples. Prediction model has been developed and validated with respect to theoretical and experimental values. Strong correlations exist between the predicted and experimental values and found suitable for predicting compressive strength and deformation of wallettes.