Authors:G. Lizia Thankam, T.R. Neelakantan, and S. Christopher Gnanaraj
Fly ash-based geopolymer fine aggregate is a potential replacement material for the natural river sand as it has similar physicochemical properties. This paper reports the experimental investigation of a study conducted using this fine aggregate in concrete with a focus on the properties of fresh and hardened concrete. The geopolymer fine aggregate was developed by air curing process and oven curing method. The oven curing method yielded relatively better mechanical properties in concrete specimens. The oven curing results in better behavior at later age also. Laboratory tests were conducted to ascertain the fresh concrete density, slump value, hardened concrete density, compressive strength, tensile strength, and flexural strength of the concrete specimens. The microstructure of the concrete specimens was analyzed using scanning electron microscope which indicated the agglomeration of the fly ash particles with few voids demonstrating the higher water adsorption capacity of the same. The unreacted particles noted in the microstructure later tend to merge with the lime obtained from the hydration of cement so as to develop improved later age mechanical strength. The results on mechanical properties of the concrete indicate much similar results to that of the concrete developed with the normal river sand, which confirms that the geopolymer sand is an ideal replacement choice for natural river sand.
Authors:Hajar Benzeroual, Abdellatif Khamlichi, and Alia Zakriti
Rail monitoring is an important activity which aims to preserve the safety and availability of railways. According to statistics, the primary cause of railway accidents is due to transverse defects that occur in the rail head. These special defects develop generally in a plane orthogonal to the rail running direction. The detection of these defects is a priority to increase the safety of rail transportation. Rail control monitoring techniques mostly rely on infrared thermography, eddy currents, air-coupled acoustic sensors, and ultrasounds. The present research studies the rail diagnosis by means of a non-contact device. The focus is on ultrasonic based methods where excitation is generated by thermal elastic coupling following laser irradiation of the rail head. For the reception of echoes, a special ultrasound sensor was used. In order to sense defects, phased array elements, which use multiple transducers and electronic time delays, are used to increase and to focalise the signal intensity. Flaws that have a moderate extension are better detected by the proposed method than with laser irradiation consisting of a single spot.
Authors:Mona M. Fawzy, Mohamed S. Kamar, and Gehad M. Saleh
In this study, the mineralogical content of Abu Rusheid mylonite sample was investigated and revealed that the sample is essentially composed of quartz and feldspar (72.14% mass), muscovite (16.6% mass), and contains heavy economic polymetallic minerals of about 2.65% by mass. By studying the differences in the physical properties of this mineral content, a proposed flow sheet was set up to explain the successive physical upgrading steps for concentrating and separating the valuable minerals content and getting rid of the associated gangue minerals. Industrial, economic and strategic polymetallic minerals were identified at Abu Rusheid mylonite sample, including cassiterite, titanite, brass, kasolite, monazite, and uranothorite. A group of sulfide minerals also existed as pyrite, arsenopyrite, galena, and molybdenite in addition to the presence of fluorite and iron oxides bearing rare earth elements (REEs) and base metals. Using dry high intensity magnetic separation followed by wet gravity separation and flotation, three concentrates were obtained; heavy paramagnetic concentrate (monazite, columbite, brass, and jarosite), heavy diamagnetic concentrate (zircon, kasolite, uranothorite, cassiterite, and sulphide minerals) and muscovite concentrate for industrial uses. Physical processing of Abu Rusheid mylonite sample was carried out to produce high grade mineral concentrate used as a raw material for chemical treatment to extract economic elements that necessary for several industries.
A total of 46 Staphylococcus aureus isolates from fish and ground beef were tested for the agr types, icaABCD genes, and biofilm formation at 12, 25 and 37 °C by the microtiter plate and the MTT assays. All isolates were positive for the icaABD genes, while 97.8% were positive for the icaC. All isolates produced biofilms at 37 and 25 °C, but 93.5% of them were also biofilm producers at 12 °C. There was no significant difference in biofilm formation between 25 and 37 °C using the crystal violet assay (P > 0.05). However, statistically significant differences were detected between 12 and 25 °C as well as 12 and 37 °C (P < 0.05). All isolates were significantly different in biofilm production by the MTT assay at all tested temperatures. Furthermore, a relationship between the presence of the icaABCD genes and biofilm formation was observed. The agr type I was the most prevalent (54.4%) among the isolates, followed by agr type II (41.3%) and agr type III (9.6%). In this study, the S. aureus isolates exhibited biofilm formation ability responsible for persistence of bacteria in foods, which may lead to food spoilage and human health problems.
Authors:B. Baráti-Deák, Á. Belák, and Cs. Mohácsi-Farkas
Previously isolated Pseudomonas lundensis CP-P-5 had antagonistic activity against Salmonella Hartford, Yersinia enterocolitica, and Escherichia coli. In this study, determination of its antagonistic mechanism and potential field of application in food industry was aimed. Using cellophane-test and microcultures of the test strain's cell-free supernatant mixed with the pathogens, our results showed that cells of P. lundensis CP-P-5 and its concentrated cell-free supernatants were effective against the foodborne bacteria, and the supernatants contained more than one compound responsible for inhibitory activity. Searching for the antagonistic compound, NaOH, protease, and heat treatments were done to the supernatants, and proteolytic activity and siderophore production were also tested using the antagonistic strain. Our results support the potential applicability of P. lundensis CP-P-5 as a bioprotective agent against foodborne pathogens in food processing environments.
Authors:Muaayed F. Al-Rawi and Muhanned F. Al-Rawi
Most applications in engineering use a data acquisition device hooked up to a personal computer for data processing. Finding less costly, easily accessible and reliable devices will make personal computer (PC) based data acquisition systems less difficult. A soundcard may be used as such a device for it is standard in almost every PC. It can also process any voltage signal within its limits. This paper proposes a way to enable the PC to be used as an oscilloscope. A voltage signal is acquired via the soundcard LINE IN port. The maximum and minimum input signal amplitude requirements for the soundcard are established to be +1 V and –1 V respectively. Based on these findings, hardware circuitry is designed to clip any high amplitude input signals to the range of ±1 V while allowing low amplitude signals to go through to the soundcard unclipped. MATLAB is then employed to acquire, process and display the signal. The final output from MATLAB is compared with the original signal to determine accuracy of the designed oscilloscope. Analysis of the results obtained shows that the final oscilloscope designed enables the soundcard to process input signals with a high level of accuracy. The final design yields a hardware cost at a fraction of an iPod while providing an elegant user interface. This makes it suitable for college students, basement hackers and even professional engineers.
Authors:Siddavatam Naresh Kumar Reddy and Mohmad Marouf Wani
The study aims to examine the effects of palm biodiesel blended with additives in the compression ignition (CI) engine. Biodiesel as fuel was limited by challenges such as lower calorific value (CV) and higher viscosity while increasing brake specific fuel consumption (BSFC) and nitrogen oxides (NOx) emissions. Nanoparticles and antioxidant additives added to biodiesel play an essential role in avoiding the hindrances of biodiesel. The antioxidants combined with biodiesel reduced NOx emissions by eliminating decomposing peroxides, free radicals, and preventing free radicals' chain reaction. The Significant characteristics of nanoparticles are high CV, high thermal conductivity, and higher surface to volume ratio. These characteristics are used to improve the CI engine's performance and emissions by using nanoparticles blended with biodiesel. Five different test blends of Diesel, B20, B20TO, B20AO, and B20AOTO were prepared. The result showed high brake thermal efficiency (BTHE) and decreased BSFC, exhaust gas temperature (EGT), hydrocarbons (HC), NOx, and HC emissions by using the B20AOTO fuel blend contrasted with other biodiesel blends.
Authors:B.L. Dinesha, S. Hiregoudar, U. Nidoni, K.T. Ramappa, A.T. Dandekar, and M.V. Ravi
The present study emphasised the efficiency of chitosan anchored titanium dioxide nano-adsorbent on dairy industry effluent treatment. Chitosan titanium dioxide nano-adsorbent was synthesised by using chemical precipitation method and characterised for its particle size, surface morphology and texture. A four-factor-three-level Box–Behnken design along with response surface methodology was used to optimise the adsorption process parameters. Linear, two factor interaction, quadratic and cubic model techniques were used to demonstrate the influence of each parameter and their interaction effects on the responses. The quadratic models derived from the experimental data were used to predict the maximum per cent reduction of biological oxygen demand (BOD) and chemical oxygen demand (COD). The optimised treatment combination for maximum per cent reduction in BOD (90.48%) and COD (82.10%) was found to be initial concentration of 100 mg L−1, pH of 7, dosage of 1.25 mg L−1 and contact time of 100 min.
Authors:Ali Kareem Abdulrazzaq, György Bognár, and Balázs Plesz
This paper presents a combined electro-thermal model to serve the aim of accurate output power prediction of photovoltaic systems, based on the concept of the thermal energy balance. The electrical sub-model is built based on fitting a surface to the current-voltage curves collected under wide range temperatures and irradiances. For this purpose, the current-voltage characteristic curves are reproduced using two different methods. The thermal sub-model considers all the effective heat transfer mechanisms to estimate the photovoltaic module junction temperature. The Newton-Raphson iterative method is used as a solving algorithm to calculate the photovoltaic junction temperature. The collected results prove the applicability of the model under a wide range of environmental conditions.
Authors:Ahmed A. Hashim, Khalil I. Mahmoud, and Hussein M. Ridha
In embedded systems that necessarily require a steady source of power and (or) attaches to a sensor(s), there are opportunities to mix small batteries to supply such power. The aim of this research is to optimize the geometry and shape of piezoelectric cantilevers to harvest more power. Several piezoelectric cantilever geometries with various shapes (rectangular, triangular, circular, and trapezoidal cross section) are tested in COMSOL multiphysics simulator to find the best geometry that provides the highest accomplishable power. The most efficient geometry was found to be conferred by the trapezoidal, cross section cantilever. Next, another improvement method was applied to maximize the harvested power of the cantilever by modifying the shape of the trapezoidal cantilever structure through increasing the number of its faces. The results demonstrated that the highest output power (36 mW) was produced by the four faces, trapezoidal cross section design of cantilever.