Sultan Qaboos University Scientific Journals
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A comparative study of filtration rate of water-based mud between silica and zinc oxide nanoparticles of different sizes for the deep well application
Full text linkIn the oil and gas industry, drilling mud plays a vital role in the drilling process. However, during the drilling process, various factors such as the filtration process, the formation of a mud paste, and the pressure variation on the well walls can significantly impact the designs and complications in the well, in addition to changing the characteristics of the reservoir. One of the challenges in the drilling process is the leaching process, which can cause various problems including the rearrangement of pressure in the vicinity of the wellbore, swelling, and a variation in the strength characteristics of the rocks. These problems can lead to the insecurity of the wellbore, cavity formation, and precipitation. Therefore, it is crucial to displace the front reservoir fluid from the well and redistribute the pressure near the well to reduce the outflow risks of the well. To address these challenges, this study aims to analyze the filtration rate of water-based mud with silicon dioxide and zinc oxide nanoparticles. The water-based mud used in this study was made by combining various chemicals such as Caustic Soda (NaOH), Sodium Chloride (NaCl), Xanthan Gum, Starch, HT Starch, Calcium Carbonate (CaCO3), and Barite for usage in a deep well. In addition, different concentrations of HT starch with both silica and zinc oxide nanoparticles were also investigated. The drilling mud's filtration properties were determined using HPHT and API filter presses, which were used under very high pressure and high temperature (HPHT) and low pressure and low temperature (LPLT) conditions, respectively. The study found that nanoparticles provide better filtration rate performance as opposed to conventional mud. Notably, the use of zinc oxide and silicon dioxide nanoparticles reduced the HPHT filtration rate of conventional water-based mud by 26.2% and 52.3%, respectively
Analysis of Heavy Metal Pollution in E-Waste Dumpsites From Two Local Government Areas in Ogun State, South Western Nigeria
Full text linkDumping sites in general have been noted to be sources of pollution in the environment and e-waste dumping sites are not exempted. A study on the pollution of heavy metals in two local government areas (LGAs) in Ogun State was investigated. An atomic absorption spectrophotometer (AAS) with model specification 210 VGP from Buck Scientific was used in the analysis. As, Cd, Co, Cr, Cu, Fe, Ni, Pb, and Zn were detected. Cd, Cu in two areas, Fe, Pb in four areas, and Zn concentrations were above the World Health Organisation permissible limit. Analysis indicates that the contaminant factor (CF) varies from low to severe at both LGAs, however, CF of cadmium is severe in all the sites, which signifies that all the areas are not suitable for agriculture.
Further results indicate that the Pollution Load Index (PLI) value is greater than one at all dumpsites, signifying that the sites are polluted. Pearson correlation shows a comparatively strong positive correlation (r= 0.826) between Ijebu-Ode and Ijebu-North Local governments. The predominant results suggest that proactive monitoring should be maintained, and remediation is required, including source identification, pollution management, and soil restoration approaches.
Keywords: Contaminant factor; Pollution; E-waste; Dumpsite; Ecological risk; Heavy metals
Design of Pseudo-LFSR Based Physical Unclonable Function
No full textPhysical Unclonable Functions (PUFs) are primarily used for authenticating hardware devices. The objective of this research is to generate a large set of challenge-response pairs to strengthen the PUF. The Pseudo-LFSR PUF design relies on LFSR but does not contain any shift register; instead, it employs combinational circuits like inverters and XOR gates. The PUF's strength is based on the quantity of challenge-response pairs it possesses, with a larger set indicating better security and authentication. The proposed PUF has significant advantages, such as producing a large-bit response, with n bits of response captured from a single n-bit challenge. Moreover, the mapping of challenge and response pairs can be varied without disrupting the hardware structure. Typically, Physical Unclonable Functions are implemented on FPGAs and ASICs. This study discusses the detailed design of a strong LFSR-based PUF and how the modified design increases the challenge-response pairs
Comparison between conventional bacterial culture and rtPCR in identifying some dairy cow mastitis causative agents
No full textAll dairy farms worldwide suffer from mastitis, the most prevalent and costly disease. Since the diagnosis of any intramammary infection is based on the identification of the infectious agent and the time taken by the identification method play an important role in disease management, this study compares routine in vitro microbial culture and RT-PCR in identifying mastitis causative agents. Out of 9,000 Holstein milking cows in the herd, 83 milk samples were aseptically taken from cows with clinically verified mastitis in the first few months of 2019. The CHROMagarTM Mastitis kit is used in microbial culture for both gram-negative and gram-positive bacteria, along with Edwards Medium HiVeg Base, Modified Medium. On the other hand, the King FisherTM Duo Prime Purification System, the Mag MAXTM Core Nucleic Acid Purification Kit, and the VetMAXTM Masti Type Kit were utilized for each sample to conduct the rtPCR experiment and DNA extraction. In a comparison between in vitro microbial culture and rtPCR using 83 milk samples from mastitis cases with clinical confirmation, all data analyzed by the Chi-square test and the ROC curve showed that rtPCR was found to be more effective than the bacterial culture approach in a comparison analysis (chi-square = 0.27, P = 0.59) and (AUC = 0.653). With its high analytical accuracy and potential for application in regular bovine intramammary infection testing services, the rtPCR assay is a highly promising test
Affine subgroups of the affine Coxeter group with the same Coxeter number
Full text linkAffine subgroups having the same Coxeter number with the affine Coxeter groups W(An), W(Dn), and W(En) are constructed by graph folding technique. The affine groups W(Cn) and W(Bn) are obtained from the Coxeter groups W(A2n-1) and W(D2n-1) respectively. The affine groups W(E6), W(D6) and W(E8) lead to the affine groups W(F4), W(H3), and W(H4) respectively by graph folding. The latter two are the non-crystallographic groups where W(H3) plays a special role in the quasicrystallographic structures with icosahedral symmetry. A general construction of the affine dihedral subgroups is introduced, some of which, describe the existing planar quasicrystallography. In the construction of the root systems, sets of orthonormal vectors are used but a special non-orthogonal set of vectors in the formulation of the root system of W(An) is also introduced which has practical applications in the construction of the lattices An and An* and their Delone and Voronoi cells
PREPARATION AND APPLICATION OF CONDUCTIVE TECHNICAL FABRICS TO SMART TEXTILES
Full text linkCotton fabrics were used in this study to create electrically conductive pathways through printing with conductive materials. Graphite and a mixture of graphite oxide with manganese oxide were utilized as conductive inks in screen printing. To create the conductive ink, conductive materials were mixed with other substances such as thickener, moisturizer, and water. The viscosity of the ink was 10 mPa.s. After printing on the cotton fabric samples, the effect of conductive concentration on electrical conductivity was examined. It was found that a 5% concentration of graphite achieved the highest conductivity (1.75 × 10-5 S.cm-1). To further improve conductivity, multiple layers of conductive ink were printed on the fabric. Three layers were applied, with the first and third containing graphite and the second containing graphite oxide and manganese oxide (battery core). The conductivity values reached 6.5 × 10-3 S.cm-1. This conductive fabric was used in the creation of electronic smart clothing to measure the human body temperature index. The conductive ink printed on the fabric served as a link between electronic components, transmitting electrical signals. In addition, a smart product using conductive yarns was created as a comparison to the conductive ink. Results showed that the sensor signal was transmitted well and readings were consistent
Effect of application time on the efficacy of Trichoderma spp. to biologically control sunflower charcoal rot
Full text linkSunflower (Helianthus annuus L.) is considered as one of the most important oilseed crops in Egypt and worldwide. It is being infected with many pathogens, among these pathogens Macrophomina phaseolina (Tassi) Goid the causal pathogen of charcoal rot is the most prevalent one, and responsible for severe economic losses on sunflower. Fourteen isolates of M. phaseolina were collected from naturally infected sunflower plants. Pathogenicity testes revealed that tested isolates varied significantly in their pathogenic capabilities. But all of the tested isolates were pathogenic and incited the symptoms of pre- and post-emergence damping-off as well as symptoms of charcoal rot. In this study, antagonistic capabilities of 26 isolates of Trichoderma spp. were investigated under both laboratory and greenhouse conditions. in vitro, T. harzianum (T8) and T. hamatum (T12) proved to have high antagonistic capability against M. phaseolina fungus with inhibition percentage of 62.13% and 61.33%, respectively. Furthermore, these two isolates proved to have a high ability to control charcoal-rot disease. Data of greenhouse experiments showed that application of T. harzianum (T8) and T. hamatum (T12) decreased charcoal rot disease severity by 30.33 and 24.16% respectively. Time of application played a critical role to increase the efficiency of Trichoderma spp. to control charcoal rot. In this experiment Trichoderma was implemented into soil at different application dates to study the effect of application date on the efficiency of bioagents to control charcoal rot. Results of this experiment showed that the highest reduction in disease severity occurred when T. harzianum (T8) was applied seven days before soil infestations with M. phaseolina (38.40%). Data also demonstrated that application of either T. harzianum or T. hamatum led to significant increases in the percentage of survival plants with 72.5% and 68.33%, respectively. This study suggests using Trichoderma spp. could be an efficient method to control sunflower charcoal rot.
Keywords: Sunflower, Macrophomina phaseolina, charcoal rot, T. harzianum, T. hamatum
Assessment of the Physicochemical Properties and Antioxidant Content in a Variety of Omani Honey Samples
Full text linkHoney, a natural product with effective medicinal properties and exceptional energy content, holds a significant place in the hearts of consumers. This study evaluated the pH, free acidity, conductivity, sugar composition, and total antioxidant content of eight types of rare honey produced in Oman. Additionally, well-known types of honey such as Sidr and Sumur, along with some commercial honey samples, were studied for comparison purposes. A simple and innovative paper-based analytical device, recently developed by our group, was applied as an appropriate alternative to time-consuming chromatography-based methods. The findings revealed a low sugar content in a type of honey called “Aitman” (30.4±1.0%), while other rare types of honey showed sugar content within the normal range (45-75%). Additionally, fructose was identified as the primary carbohydrate in almost all samples, followed by glucose. The free acidity of the samples was comparable to Sidr and commercial honey samples but was lower than that of Sumur honey. Interestingly, the total antioxidant content of native rare honey (116.9-325.4 meq gallic acid/Kg) was substantially higher than that of all other analyzed varieties (101.5-196.6 meq gallic acid/Kg). These findings provide valuable insights into enhancing the quality of Omani honey. By guiding the industry to produce premium-quality honey, this research can improve the domestic and international standing of Omani honey. To the best of our knowledge, this is the first report on the evaluation of these rare types of honey produced in Oman.
Keywords: Omani honey; Physicochemical properties; Sumur; Sidr; Rare honey
Improved ADRC-Based Integral Flux Observer for IPMSM Sensorless Control
Full text linkAn interior Permanent magnet synchronous motor (IPMSM) drive employing sensorless control strategies offers to simplify the design of servo systems, reduce costs, and improve reliability, thus attracting significant research attention from both academic and industrial sectors for decades. The straightforward configuration and decreased application prerequisites make model-based sensorless control approaches highly popular. Notably, the conventional first-order integrator flux observer technique exhibits remarkable robustness owing to its minimal reliance on motor parameters. However, the conventional first-order integrator experiences a DC drift and harmonics in the estimated rotor flux as a result of non-ideal factors, such as detection errors, integral initial value, converter nonlinearities, and parameter mismatches. In this paper, an improved ADRC-based integral flux observer capable of eliminating drift is developed to achieve high-accuracy flux estimation. The efficiency of the proposed technique in eliminating the drift from the estimated flux, as evidenced by theoretical analysis, has no detrimental effect on the amplitude or phase angle of the fundamental waveform. The validity of the proposed improved ADRC-based integral flux observer is verified by sensorless vector control of a 7.5 [kW] three-phase IPMSM motor via extensive numerical simulation
Pedal Energy – Photovoltaic (PV) Integration as an Environmentally Friendly Alternative Energy
Full text linkPhotovoltaic is Renewable Energy (RE) sourced from the sun. Apart from PV, pedal power generation is also a form of RE that can be used as alternative electrical energy because humans generate this energy in the pedalling mechanism. Furthermore, single use of renewable energy has limited continuity in the load supply because it relies heavily on sources that are only available sometimes. As proposed in this research, integrating several renewable energies, such as PV and pedal energy, could be a solution. This pedal generator uses a static bicycle to produce electrical energy by utilizing the Permanent Magnet Synchronous Generator (PMSG) to convert pedal energy into electrical energy. The electrical energy produced by PV and static bicycle is stored in a battery. A constant DC voltage interfacing in an efficient battery energy storage system is needed. Buck DC-DC converters maintain constant voltage from PV and static bicycles. The results show that the converters can stabilize a voltage of 65-32 volts from the generator permanent magnet and 17.19-18.3 volts from the photovoltaic to a constant voltage of 13.8 Volts. In addition, the proposed system utilized INA219 sensors as a measuring system. The maximum sensor inaccuracy of voltage and current is 2.96% and 0.81%, respectively