Octagonal Design Research Articles

Performance Analysis of Solar Still by Using Octagonal-Pyramid Shape in the Solar Desalination Techniques

This research work explored and compared the experimental performance of a solar still having novel octagonal-pyramid shape with a single slope solar still. It is found that the novel still provides twice distillation compared with conventional still. The experiments also evaluated the desalination productivity of octagonal-pyramid solar still by varying the depth of saline water inside the basin and angle of inclination of glass cover. It is observed that the optimum condition for high distillation is obtained when depth of water inside the basin is 5 cm with angle of inclination of glass cover which is 30°. Four types of water, i.e., underground borewell water, sea water, leather industry effluent, and plastic industry effluent were also used to see the effect on distillation. Results showed that underground borewell water provides high distillation due to low density. Furthermore, the performance of the octagonal-pyramid solar still is enhanced by adding different latent heat and sensible heat materials in the octagonal-pyramid solar still. Hence, the addition of brick to the octagonal-pyramid still yields the highest productivity compared to incorporation of paraffin wax. Hence, it can be concluded that the octagonal design of the solar still has shown an increased productivity when compared to a single slope solar still (conventional still) under all the conditions.

Design and analysis of the effect of Zeonex based octagonal photonic crystal fiber for different types of communication applications

In this present work, a novel structure of octagonal cladding with two elliptical air holes based on photonic crystal fiber (O-PCF) has been presented for the application of different types of communication areas within the terahertz (THz) wave propagation. There are five layers of octagonal design shape of circular air holes in cladding region with elliptical design shape of two air holes in core area has been reported in this research work. This O-PCF fiber has been investigated by the perfectly matched layers with the finite element method. After the simulation process, our proposed O-PCF fiber shows a low effective material loss of 0.0162 cm−1, the larger effective area of 5.88 × 10–8 m2, the core power fraction of 80%, the scattering loss of 1.22 × 10–10 dB/km, and the confinement loss of 3.33 × 10–14 dB/m at the controlling region of 1 terahertz (THz). Due to its excellent characteristics, this proposed O-PCF fiber gives proficient transmission of broadband terahertz waves of signals. Moreover, for different kinds of optical communication applications and biomedical signals, our suggested O-PCF fiber will be highly perfect in the terahertz (THz) regions.

Multi-Frequency Piezoelectric Micromachined Ultrasonic Transducers

In this paper multi-frequency piezoelectric MEMS ultrasonic transducers (pMUTs) are designed, characterized and tested for nondestructive evaluation (NDE) of solids. The transducers operate in flexural mode, and are tuned to three different frequencies namely 1 MHz, 1.5 MHz and 2 MHz. The microstructural layers consist of aluminum nitride (AlN) as an active sensing layer sandwiched between metal and doped silicon electrodes. pMUTs are designed with octagonal and circular membranes. The vibration of silicon membrane assists piezoelectric element to convert energies. The transducers are modeled numerically to obtain their dynamic characteristics. Piezoelectric Multi-User MEMS Processes (PiezoMUMPs) are utilized to manufacture pMUTs. The electromechanical characterization shows that the circular design has higher figure of merit as compared to the octagonal design due to more uniform stress distribution transferred between silicon and AlN layers. It is demonstrated that the piezeoelectric layer should be deposited up to the inflection point of diaphragm deformation. This avoids the signal cancellation due to opposite polarization. The performance of pMUTs as receiver is evaluated to detect the creep damage by implementing nonlinear ultrasonic testing (NLUT). NLUT is based on detecting higher harmonics in solids due to heterogeneity in materials. Significant amplification in the second harmonics is obtained due to highly narrowband and low damping characteristics of pMUTs that improves the resolution of NLUT to detect subwavelength damage. Higher harmonics can be detected using small footprint pMUT device, which is not possible with conventional piezoelectric transducers. This allows better spatial resolution of nonlinear measurement.

Cultural and Mathematical Meanings of Regular Octagons in Mesopotamia: Examining Islamic Art Designs

The most common regular polygon in Islamic art design is the octagon. Historical evidence of the use of an 8-star polygon and an 8-fold rosette dates back to Jemdet Nasr (3100-2900 B.C.) in Mesopotamia. Additionally, in ancient Egypt, octagons can be found in mathematical problem (Ahmose papyrus, Problem number 48), household goods (papyrus storage), architecture (granite columns) and decorations (palace decorations). The regular octagon which is a fundamentally important element of Islamic art design, is widely used as arithmetic objects in metric algebra along with other regular polygons in Mesopotamia. The 8-point star polygon has long been a symbol of the ancient Sumerian goddess Inanna and her East Semitic counterpart Ishtar. During the Neo-Assyrian period, the 8-fold rosette occasionally replaced the star as the symbol of Ishtar. In this paper, we discuss how octagonal design prevailed in the Islamic region since the late ninth century, and has existed in Mesopotamia from Jemdet Nasr to the end of third century B.C. We describe reasons why the geometric pattern of regular polygons, including regular octagons, developed in the Islamic world. Furthermore, we also discuss mathematical meanings of regular polygons.

TWISTING IN THE WIND: MONUMENTAL WEATHERVANES IN CLASSICAL ANTIQUITY

Monumental weathervanes have been overlooked as a tiny but important genre of ancient bronze sculpture. This is the first collective study of all three definite examples: the so-called ‘triton’ on the Tower of the Winds in Athens, a copy of this somewhere in Rome and the winged female ‘Anemodoulion’ on the Bronze Tetrapylon in Constantinople. I propose to identify the intended subjects of these sculptures as the weather-deities Aiolos and Iris, thereby restoring a part of each monument's original meaning that was unknown to the authors of our ancient written accounts. I also suggest that monumental weathervanes were first invented in Hellenistic Alexandria, which may explain why the Tower of the Winds shared the octagonal design of the Pharos, and why the Anemodoulion was mounted upon a bronze pyramidion.

Rutronik: octagonal design of the SIM-Connector from Amphenol-Tuchel Electronics offers more space

Rutronik: octagonal design of the SIM-Connector from Amphenol-Tuchel Electronics offers more space

Scaling-up of a lactose wet granulation process in Mi-Pro high shear mixers

The high shear wet granulation upscaling possibilities of a Pro-C-epT Mi-Pro 250 ml with a batch size of 40 g were investigated by down-scaling an α-lactose monohydrate wet granulation process from a Collette Gral 10 (8 l batch size) to a Pro-C-epT Mi-Pro with different bowl volumes of 5 l, and 1900, 900 and 250 ml. The wet granulation process was optimised in the Gral 10, next an octagonal design was build around the central point. Two process parameters, the impeller tip speed and the water content, were varied at three levels, which resulted in a two-factor three-level experimental design. α-Lactose monohydrate 200 M was granulated using a polyvinylpyrollidone K 30 (2.5% on dry material) binder solution. The granules were dried at 25 °C for 24 h, sieved and characterised. The granules were compressed to tablets. In all mixer volumes the used impeller tip speed range did not influence the granule or tablet properties. In all bowl volumes the influence of water concentration on actual yield, particle size distribution and granule friability was similar. All batch sizes resulted in tablets of similar quality. For the selected formulation the lab scale Mi-Pro high shear mixers with different bowl volumes could be used to determine the optimal process parameters and to scale up to the Collette Gral 10 pilot scale.

Influence of pH, nitrogen and phosphorus sources on the production of hepatitis B virus pre-S2 antigen by Hansenula polymorpha.

Experimental design techniques were used to study the influence of the composition of the culture medium on the production of hepatitis B virus pre-S2 antigen by the methylotrophic yeast Hansenula polymorpha. pH, phosphoric acid, ammonium chloride and yeast extract concentrations were selected as experimental factors and their influence was investigated using Central Composite design techniques. The results indicated that antigen yield was maximized at high pH and in a culture medium containing both ammonium chloride and yeast extract. Phosphoric acid was found to have a detrimental effect on antigen production. This study allowed a 50% increase in antigen production in a medium in which the yeast extract concentration was decreased to 32 g/l. These optimal conditions have been confirmed with an octagonal design experiment. Moreover, it was shown that the antigen produced was very stable up to at least 8 days after induction and that the yeast extract concentration could be lowered to 22 g/l without appreciable effect on antigen yield. The increase in antigen production was not due to an increase in cell biomass, since no correlation could be found between these two parameters. The newly defined culture medium should allow a greatly increased antigen production at the fermentor level, at a lower cost and with minimal operational problems.

In vitro detachment of bacteria from ruminal digesta by buffered sodium oleate solutions

The effectiveness of a buffered sodium oleate solution was evaluated for detaching bacteria from ruminal digesta samples. A response surface derived from an octagonal design was used to determine the pH and concentration combination for maximum detachment of total and cellulolytic bacteria. The total number of bacteria detached increased up to 81% over control with treatment of a pH 8.8 and 1.5% sodium oleate solution. The recovery of cellulolytic bacteria was decreased to 35% of control with treatment of a pH 9.0 and 0.1% sodium oleate solution. Attempts to improve the recovery of viable bacteria exposed to sodium oleate solutions were unsuccessful. This response surface design identified an optimal pH and concentration that were consistent with existing information regarding detachment of total bacteria, and suggested that sodium oleate, at the concentrations tested, was toxic to the cellulolytic population of the rumen.