Sirte University Scientific Journal

Experimental Works to Improve Power Quality of the Existing PV Solar Inverters

2023-06-01T14:36:17+00:00

Solar energy development has attracted significant research attention, due to it offering many advantages that include being a safe, clean, and non-finite resource with no operational costs or moving parts. Therefore, solar systems are expected to play a significant role in the future of electricity supply, but, the power electronics used to connect these resources to the grid may face problems. This paper presents improving the power quality of the existing PV inverter by integrating it with a bidirectional inverter along with a battery storage system. A 6 kWh AC Mini-Grid is developed and tested with a PV inverter. The experimental works found that the PV inverter has high the Total Harmonic Distortion (THD) of the output current that may reach up to 24%, while when this PV inverter was connected to the proposed system, the THD of the output current of the PV inverter was reduced to 0.64 %. The response of the battery storage is very smooth and fast, providing a stable and reliable output power in both cases when a domestic load is supplied from the solar system or the battery storage.

Design, modeling and simulation of a square quartz resonant pressure sensor

2023-06-01T15:00:05+00:00

This paper establishes the Finite Element Method FEM model of a practical Quartz beam resonator attached to a square diaphragm, which is used for measuring the pressure, based on sensing mechanism of a resonant Quartz pressure sensor. The relationship between the basic neutral frequency of the beam resonator and the measured pressure is calculated, analyzed and investigated by making use of the established FEM model. Some important qualitative and quantitative results on the natural frequency- pressure relationship of the beam resonator and the microsensor are obtained. Finally, based on the differential output scheme, a set of appropriate parameters of the sensing structure is determined, the frequency range is (661.839~892.208) kHz for the beam, which is located at the outer edge.

Design M×N Adaptive Antenna Array for Personal - Satellite Communications Link

2023-06-01T17:32:36+00:00

This paper introduces a proposed design of an adaptive rectangular microstrip antenna array for personal - satellite communications link operating at 3 GHz. The main purpose is to design an antenna with an adaptive narrow main beam bandwidth directing up to the satellite by using smart antenna techniques. The performance of the proposed planer antenna in terms of patch width and length, number of elements along the x-axis and y-axis, the spacing between the elements, directivity, distribution, weighting coefficients, and radiation pattern are studied and optimized using Matlab software. High directivity of 13.12 dB is achieved. Therefore, high orbits satellites cab be utilized to reduce the cost.

Modified Empirical Models for Predicting Liquid Film Thickness in Different-Sized Vertical Pipes

2023-06-01T17:38:18+00:00

The liquid film thickness is a vital parameter in many engineering applications such as production equipment of oil and gas. Good control of fluid flow in such equipment can lead to maintaining a continuous liquid film on the pipe wall and hence increasing the anticipated production rate and avoiding catastrophic consequences. Therefore, a precise estimation of liquid film behavior is required to achieve the targeted production rate and overcome the above-mentioned issues.

Even though a considerable number of empirical models were reported, most of these assessed the fluid flow based on small-sized pipes. These models incorrectly predicted the film thickness if applied to a large-diameter.

This work was aimed at developing correlations for gas-liquid two-phase fluid in order to be applicable for different-sized pipes. The new correlations were evaluated against a wide range of experimental data of liquid film and for different diameters collected from the literature on vertical pipes. It was found that the new correlations can be precisely used for predicting the liquid film behavior in small and large pipe diameters.

The Effect of Laminar and Turbulent Flow on Phase Change Materials for Energy Recovery

2023-06-01T18:16:06+00:00

Phase change materials (PCMs) can be used for energy storage and recovery, and it is interesting to see what effect laminar and turbulent flows would have on them. a phase change material is a substance with a high heat of fusion, melting, and solidifying at a certain temperature, which is capable of storing and releasing large amounts of energy. laminar flow is a slower and smoother flow where the flow is parallel and there is no disruption between layers. turbulent flow is more chaotic, and its flow pattern cannot be predicted. paraffin wax was used as the PCM, and water was used for turbulent flow while mineral oil was used for laminar flow. the goal of this research is to improve the efficiency of a system by performing experiments with corrugated plates and paraffin wax as the PCM within the recovery unit. corrugated plates were used as an advanced material and channels of media which carry the thermal fluid (water or mineral oil) to the back plate of the unit which was occupied with the PCM. the experiment measured the temperature in and out from the unit to estimate how much watts (power) that the unit can save in the molten wax and, monitor the temperature inside the PCM using implanted thermocouples. the approach of this work is to collect temperature as a function of time to find how much energy units are used to reach the charging point and reverse the flow to retrieve energy from the unit.

Water Injection Performance in the Abu-Attifel Oil Field Using the Hall Plot

2023-06-01T18:40:24+00:00

Waterflooding is the most common improved oil recovery (IOR) technology used to improve oil recovery. The water flooding project should be launched at an optimal time to increase the recovery and maximize profits. It is important to have tools available to monitor and assess the wells that are additionally cost-effective. Not only the monitoring of the whole flooding project but also the monitoring of each individual well is important to guarantee a successful oil recovery. In this paper, the Hall plot analysis was applied to evaluate the injection performance of M20 and M21 injection wells in the Abu-Attifel oil field. The Abu-Attifel oil field was discovered in 1967 and began production in 1972 with a weak water drive and an ongoing injection process. Hall’s method is a simple and cheap tool used to evaluate the performance of water injection, and it is based on the assumption of steady-state radial flow. It is concluded that the hall plots showed a change in slope after an initial period of fill-up for both injectors, which indicates the occurrence of skin due to the near-wellbore plugging.

Comparative Study of Reinforced Concrete Design of Short Columns between BS 8110 and ACI 318-11 (Codes)

2023-06-01T19:31:25+00:00

In several countries around the world and Libya on of them the absence of a national design code, these leads structural engineers to use BS 8110, ACI 318 and quite a number of other structural design codes for the design of reinforced concrete structures. The principles and design approaches of these codes differ from one another. Also, some codes are more economical than others. This study compared BS 8110-97 and ACI 318M-11 in terms of the analysis and design of short column with particular emphasis on the area of longitudinal reinforcements required, with the aim of determining which of the two codes provides the most economic design. The super-structure of a seven-story reinforced concrete service building was modeled, analyzed and design using Auto Desk Robot Structural Analysis (2015) program taking into account dead, live and seismic loads. The percentage difference between the areas of steel required by the two codes was calculated with the ACI code as the base line. The average percentage difference for all columns was found to be about 21.5% indicating that the BS 8110 code requires less amount of reinforcement.

Subordination Results of Analytic Functions Defined by Convolution

2023-06-01T20:42:43+00:00

The purpose of this paper is to study some known interesting subordination results for analytic functions defined in the open unite disk U={z∈C:|z|<1}. Especially, it is to obtain subordination results for a family of univalent functions which are defined by means of the convolution. Relevant connections of the results presented here with those obtained in earlier works are also pointed out. However, our results generalize and extend some earlier results in the literature.

Boundedness Criteria for Solutions of Some Nonlinear Differential Equations of Second Order

2023-06-01T20:49:49+00:00

Mathematical modelling phenomena of most applied sciences is associated with second order nonlinear diﬀerential equations, which are not easily solvable. Therefore, the study of behavior of the solutions has attracted the attention of many mathematicians worldwide. In the present work, we discuss some clear assumptions for the boundedness of all solutions of some non-linear differential equations of second order. The main tools in the proofs of our results are Gronwall's inequality and Bonnet's Theorem. The results obtained here extend and/or improve some of well-known results in the literature. Further, some illustrative examples are provided to show the applicability of the new results

Estimation of annual gonadal dose equivalent and cancer risk for the barley samples in Libya markets

2023-06-01T21:09:00+00:00

Due to its important role in human safety, natural radioactivity has garnered a lot of attention worldwide. Barley is one of the basic and important for human beings. Therefore, the measurement of natural radioactivity is a critical because of its direct impact on human safety. In this research, quantification has been made of natural radionuclide concentrations using NaI(Tl) gamma-ray spectrometry. The analyses of samples reveal the mean activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K% are found to (4.68) ppm, (17.14) ppm and (0.49) % respectively. Also estimated annual gonadal equivalent dose (AGED) resulting with an average (0.47) mSv.y^-1 where was greater than globally limits, while the average value of cancer risk (ELCR) (0.29) equals the international permissible limits. The study can be considered as a basis for future studies on this basic substance in food.

Study of Reactions of 2,2-Dichloro-N-(Substituted Phenyl) Acetamide With 1H-Benzo[d]1,2,3-Triazole

2023-06-01T22:45:40+00:00

Synthesis of 2,2-dichloro-N-(substituted phenyl) acetamid (a_1-4) via treated substituted aniline with dichloroacetyl chloride in the present of anhydrous K₂CO₃ in CH₂Cl₂. The later 1H-benzo[d]1,2,3-triazole (2) were reacted with 2,2-dichloro-N-(4-chloro phenyl) acetamid (a₁), 2,2-dichloro-N-(3-nitro phenyl) acetamid (a₂), 2,2-dichloro-N-(4-methoxy-3-nitrophenyl) acetamid (a₃), 2,2-dichloro-N-(p-tolyl) acetamid (a₄) in the present of anhydrous K₂CO₃ in acetone under reflux to give 2-(1H-benzo[d]1,2,3-triazol-1-yl)-2-chloro-N-(4-chloro phenyl) acetamide (3), 2-(1H-benzo[d]1,2,3-triazol-1-yl)-2-chloro-N-(3-nitro phenyl) acetamide (4), 2-(1H-benzo[d]1,2,3-triazol-1-yl)-2-chloro-N-(4-methoxy-3-nitro phenyl) acetamide (5) and 2-(1H-benzo[d]1,2,3-triazol-1-yl)-2-chloro-N-(p-tolyl) acetamide (6) respectively.

All the synthesized compounds were characterized on the basis of melting point, TLC, IR, ¹HNMR, ¹³CNMR and mass spectrometry.

Estimation of Serum Vitamin D Level among Patients Attending some Polyclinic in Sirte Libya

2023-06-01T23:31:10+00:00

An Analytical study was conducted to detect Vitamin D Deficiency (VDD) and its associations to age and gender of patients. The study took place during the fourth quarter of 2022. 244 patients were subjected to blood analysis to determine the concentration of 25 hydroxyvitamin D in serum. The sample was consisted of 28.7 % males and 71.3 % females. 48.8 % of the sample (119 patients) were suffering from Vitamin D Deficiency (VDD). Most patients, who had Vitamin D Deficiency (VDD), belong to age group of 26 -65 years old 59.66 % of sample with an average of vitamin concentration 13.23 ± 3.7 ng/ml. The results indicate that 21.7 % of patients had severe vitamin D deficiency and 27 % of them had insufficiency vitamin D whereas 6.1 % had higher vitamin D concentration than normal level. The study concluded that females are more likely to suffer vitamin D deficiency, as the infection rate reached 78.99 % of the samples. The infection rate was higher between the 26 -65 age group at 58.5 %. The results showed that females are more susceptible to infection than males, especially between 26 -65 aged groups.

Impacts of Used Cigarette Butts on Soil Properties and Local Plants Growth

2023-06-02T06:50:16+00:00

Cigarette butts (CBs) are the most common litter item on Earth but no long-term studies evaluate their fate and ecological effects. They are prevalence wastes in the environment and hazardous wastes usually littered by smokers. The present study aimed to investigate the impacts of used cigarette butts on soil properties and local plants growth. A petri-dishes germination experiment was carried out under controlled laboratory conditions to examine the effects of cigarette’s butts extract (0, 30, 60 & 90%) on seed germination of some types of ornamental and wild plants (Moringa oleifera, Dodonaea viscosa, Melilotus officinalis, Chrysanthemum indicum). Results reflected significant changes and impediments to germination by increasing butts extracts concentration. Cigarette butts inhibited bacterial community, where the higher reading was recorded with control ≥ 3.00×10^-7 CFU/ml, followed by 2.81×10^-7 CFU/ml for 30% butts extracts, 2.29×10^-7 CFU/ml for 60% treatment and the lowest was 4.00×10^-5 CFU/ml for 90%. One-month plant species (Melilotus officinalis) was grown in Clay loam soil pots treated with 0, 1, 6 & 9 cigarette butts to examine their effects on soil characterization. The results indicated that cigarette butts able to affect the soil physico-chemical properties, where they increased the pH, EC & Soil alkalinity in tested soil. Sodium concentration were increased from 11.9 to 103.0 mg/kg.

Influence of intraoperative factors on the outcome of root canal treatment (Part 2): A retrospective clinical study

2023-06-02T06:58:24+00:00

Aim: to assess how intraoperative prognostic variables (Treatment session, apical preparation size, Root canal filling length, Obstruction, Type of irrigant, Acute flare up) affect the outcome of the initial endodontic therapy. Methodology: Out of 109 treated patients, 91 had completed medical and dental data. A total of 146 received endodontic treatment with 408 Canals. All procedures were carried out in 2018 and 2019, in a private dental clinic in Sirte, Libya. The criteria of the European Society of Endodontology were used to assess the treatment outcome. The level of significance was set at p-value < 0.05%. Results: three factors, namely, the Apical preparation size (Chi-square = 49.7, p-value = 0.0001), the type of irrigant (Chi-square = 18.7, p-value = 0.001) and the root filling extension (Chi-square = 15.6, p-value = 0.016) were found to have a significant effect on the success rate at < 0.05 level of significance. Conclusion: Quantitative results lead to the conclusion that three intraoperative factors, namely, the apical preparation size, the type of irrigant and the length of root filling were found to have a significant effect on the success rate of root canal treatment.