Applied Mechanics and Materials Vol. 248

Abstract: Drinking water is contaminated from the chemicals and biological impurities around the world mostly in rural area. These contaminations may come from natural sources and leaching of waste deposits which cause a major human health hazard in many parts of the world. There has been very little scientific research work into the use of natural flocculants to purify raw water. Most of the research studies that have been done on conventional water purification in developing countries have focussed on conventional water purification systems using inorganic and poly-electrolyte flocculants. Such systems are very expensive for rural communities in these developing countries as our objective is to provide water that is safe for human consumption by using facilities which can be constructed and operated at a reasonable cost. There is a need to evaluate natural flocculants for conventional water treatment in order to develop inexpensive ways for developing countries to purify their water. In this study, the natural flocculants such as Moringa seeds powder, Guar Gum seeds powder, aluminium sulphate and polyelectrolyte were tested in a jar test apparatus to determine the optimum operating conditions for water or wastewater treatment plants. The results showed that the addition of Moringa Oleifera seeds powder, Guar Gum seeds powder, aluminium sulphate and polyelectrolyte flocculants improved the quality of raw water. The raw water samples from all treatment plants showed a reduction in turbidity that was more than 70% when all the four flocculants applied synergistically.

Abstract: Two species of tigernut tuber (yellow and brown i.e. fresh and dried) were processed in different ways to formulate three new products, Product 1-Apple Tigernut Beverage (ATB), Product 2-Pineapple Tigernut Beverage (PTB) and Product 3-Coconut Tiger nut Beverage (CTB). ATB, PTB and CTB were blends of Apple juice, Pineapple juice and Coconut milk with the Tiger nut milk (yellow and brown mixed separately) by substitution at ratio (YTM:AJ, BTM:AJ) (YTM:PJ, BTM:PJ) (YTM:CJ, BTM:CJ) 100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100. These samples were evaluated for their chemical composition, physiochemical properties, vitamins, mineral content, sensory and shell life and the samples maintained a good statue. Statistical analysis was carried out in chemical composition of which the result significant difference (P ≤ 0.05) existed between yellow tiger nut milk brown tiger nut milk at 100:0, 80:20, 60:40, 50:50, 40:60, 20:80 but sample 0:100 of AJ, PJ and CJ were not significantly difference (P > 0.05). From the chemical composition results it was observed that the beverages had high content of moisture, carbohydrate and energy value. However, the beverages were fairly rich in protein, ash and fat contents. The microbial result of fungi was a bit at variance with standard record. Although, all samples were highly accepted but coconut tigernut beverage had the highest acceptability. Microbial content ranged from zero growth to 10₃cfu/ml which was not critical to the wholesomeness of the products. Furthermore, samples were stored in an air tight container in a cool place and were seen to last for 10 days before fermentation set in, hence, the presence of CO₂ increased their shell life.

Abstract: This study investigated the development and application of banana peel for the remediation of heavy metals (Pb, Zn and Cr). Batch experimental processes as well as conditions that might influence the sorption of the metals were investigated. These conditions include effects of pH, contact time, adsorbent dose, and particle size. The applicability of the sorption process was tested on wastewater. The adsorbent activated with 0.5 M H2SO4 showed the highest percentage removal of chromium ion (88.9 %) at a pH of 6. It has been found that particle size has no effect on the removal of zinc ion and it has also been found that the removal efficiency of lead and chromium ion decreased with increase in contact time and particle size. Also, it can be seen from the results that untreated banana peel waste increases the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) values of wastewater. The results from the optimized method revealed the applicability of the method to environmental water samples. This study therefore confirms that banana peel is a promising adsorbent for the removal of chromium from industrial effluent.

Abstract: In the start stage of progressing cavity pump (PCP) and the well with high ratio of gas to oil, dry friction usually happens between metal rotor and rubber stator. Therefore, it is very important to investigate wear and frictional behavior of rubber with metal under dry sliding. In this paper, the effect of speed on the friction and wear behavior of three kinds of FKM/NBR blends (FKM, NBR, FKM/NBR=5:5) with the same Shore hardness was investigated using a ring-on-block tester under dry sliding. The morphology of worn surface was measured using stereo microscope. The results show that the queuing order of wear loss and coefficient of friction is NBR

Abstract: Amorphous films of germanium (thicknesses 25 - 450 nm) were obtained on glass substrate at room temperature by the vacuum (residual gas pressure 3´10-6 mm Hg) pulsed-laser (Q-switched glass: Nd3+ laser (1.064 µm wavelength, 30 ns pulse duration, laser energy - 3 J per pulse, laser intensity on Ge target ~109 W/cm2)) deposition method. The comprehensive study of the optical and electrical properties of amorphous films of germanium showed the presence of two types (A and B) of films with different characteristics. With increasing of film thickness from 100 nm to 450 nm we observe the transition from the prevailing topological disorder (A- type) to the quantify disorder (B- type) in the region of 300-350 nm. Thicker films are characterized by a more homogeneous “network” of bonds, which minimizes the number of defects and localized states in the “forbidden” gap and, consequently, increases the resistivity and optical gap. An increase of the resistivity and optical gap is observed with decreasing film thickness (< 100 nm), which is explained by an increasing influence of natural oxidation of thin films. The results of temperature measurements for A- type films shows that the temperature dependence of resistivity is characterized by Mott's law (lnρ ~ T-1/4) in the temperature range of 100-240 K, while for B- type it indicates an activation character (lnR ~ ΔEa/kT) in the temperature range of 150-350 K.

Abstract: In order to optimize the hot deformation processing, useful and efficient mathematical models able to evaluate the different aspects of the response of plain carbon steel to hot plastic deformation are among the most important prerequisites. In this paper, a group of mathematical equations were developed according to a series of experiments data to model the austenite grain evolution, static and dynamic recrystallization during-deformation and post-deformation of plain carbon steel. And then those equations were implemented into ABAQUS6.5 (License Agreement Identifier: 27SHANU) using the VUMAT for numerical simulations of cylinder specimen compression.

Abstract: Carbon capture and storage (CCS) provides important technological solutions to reduce CO2 emission at large scale for high emission countries. CCS technology is being shaped and developed within technological innovation system. The strength and composition of actor-networks in this system make a significant impact on CCS technology development. In order to facilitate the build-up of CCS innovation system, this study analyzes the actors-networks of CCS innovation system in China and the U.S, based on social-networks analysis. It is argued that there are huge differences between China and the U.S’s CCS innovation system. Therefore, the build-up of CCS innovation system in China should take characteristic approaches and policies to accelerate CCS development in the future.

Abstract: Based on the end-face mechanical seal in Space Liquid Lubrication System, a geometry model of hydrophobic surface was presented. The Reynolds equation for controlling film pressure between the faces of micro-sculpt was solved by using the finite element method. The influence rules on end-face film pressure were studied in the surfaces of zero sculpt, micron positive (protruding) and micron negative (recessed). The effects of surface tension of the sealing medium on film stiffness, opening force and leakage rate were studied at different area ratio of micron positive (negative) and the end face. The pressure balance performance was construed between the seal end face. The calculation results show that the leakage rate will be lessen more than 30% by the sculpting of micron positive (negative). The opening force and leakage rate decrease linearly with the increasing of area ratio while the area ratio () of micron positive (negative) and the end face is less than 0.2; the opening force and leakage rate reaches the minimum respectively as =0.2; but the film stiffness arrives at the maximum as =0.2. The closing force is always greater than opening force, and the seal condition is fulfilled between the end face. The research results establish the theory basis for further analysis on the performance of space liquid lubrication.

Abstract: In order to explore the possibility of enhanced creep resistance by grain size control, creep tests of stress-relieved and annealed Zr-1Nb-0.7Sn-0.1Fe cladding tubes were carried out at intermediate temperatures. The creep rate decreased significantly with increase of grain size from ~1.2 μm to 4 μm with annealing. The stress exponent was observed to be in the range of 5.0~6.5 for both stress-relieved and annealed Zr-1Nb-0.7Sn- 0.1Fe, suggesting that the dislocation climb is the rate controlling creep mechanism. It was shown that not only the creep rate decreased but also creep life increased in the annealed Zr-1Nb-0.7Sn-0.1Fe, suggesting the grain size control may provide an effective way to enhance the creep resistance in Zr alloys for nuclear application.

Abstract: The effect of heat treatment on the bending deformability and fracture behavior of roll-bonded Cu/Al/Cu clad plates were investigated. As-rolled clad plate and that annealed at 200OC exhibited the initial high load maintained for a short period and then a rapid drop of the load. The rapid softening promotes the continued localized bending once bending occurs because the work hardening due to the localized bending is negligible, leading to the localized fracture. Cu/Al/Cu clad metal annealed at 300OC, up to 450OC, initial load for bending decreased remarkably due to recovery/recrystallization, but work hardening occurred for an extended period before gradual softening took place. The initial extensive work hardening in the localized bent region tends to distribute the bending deformation uniformly, leading to the rather uniform bending. For annealed clad plates at high temperatures, the periodic cracks perpendicular to the interface were observed in the intermetallic layer and the localized slip developed both in Cu and Al emanating from the open cracks in the intermetallic layer. The localized slip marking was more evident in Cu than in Al, reflecting the lower stacking fault energy in Cu.