Mathematical analysis of the turbine coefficient of performance for tidal stream turbines

Unregulated water currents such as tides and ocean currents include energy that could be utilized for electricity production. These currents can be seen as dead bodies of water with potential energy, driven by gravity or alive moving with a kinetic energy (KE). Tidal stream turbines are a relatively new technology for extracting KE from tidal currents, which is currently in progress from development stage to industrial execution. One of the most important factors in tidal power analysis is the rotor efficiency coefficient or turbine coefficient of performance (λ). It depends on the rotor blade geometry and water velocity. This article presents a mathematical description of good interpolating functions which describe this coefficient analytically, for tidal stream turbines. Nonlinear curve-fitting solver in least-squares sense has been used in this study. Various interpolation functions have been proposed. The proposed mathematical descriptions can be very helpful for tidal power analysis and output power estimation

Improving Performances in the Public Sector: The Scientific Management Theory of F W Taylor and Its Implications for Library and Information Services

The need for improve performances in organization has always been a source of concern for management in both the public and the private sector. This paper sought to discuss the principle of scientific management theory as propounded by F.W. Taylor with the aim of ensuring that public services organizations adopts the principles for enhanced productivity, efficiency and the attainment of organizational objectives. The paper highlighted the principles of scientific management theory, and it explores how public service sector, notably the Library and Information Science segment in Nigeria, can benefit from its well tested principles. The main reason for the paper is the apparent inefficiency of the public sector, as observed and reported by several scholars over time. The Information Manager Vol. 7 (2) 2007: pp. 40-4

LC compensators for power factor correction of nonlinear loads

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEA method is presented for finding the optimum fixed LC compensator for power factor correction of nonlinear loads where both source voltage and load current harmonics are present. The LC combination is selected because pure capacitive capacitors alone would not sufficiently correct the power factor. Optimization minimizes the transmission loss, maximizes the power factor, and maximizes the efficiency. The performance of the obtained compensator is discussed by means of numerical examples

Practical considerations regarding power factor for nonlinear loads

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEThe choice of LC compensator may be constrained by the availability of manufacturers units. To account for this, the capacitor values are chosen from among standard values and for each value the transmission losses is minimized, or power factor is maximized, or transmission efficiency is maximized. The global minimum or maximum is obtained by scanning all local minims or maxims. The performance of the obtained compensator is discussed by means of numerical examples

The Assessment of Machine Learning Model Performance for Predicting Alluvial Deposits Distribution

This paper discusses the development and evaluation of distribution models for predicting alluvial mineral potential mapping. A number of existing models includes Weight of Evidence, Knowledge-driven Fuzzy, Data-driven Fuzzy, Neural-Network, Bayesian Classifier and Geostatistical Kriging. We offer classification models developed in our laboratory, where point pattern analysis was used to identify presence or absence of a known secondary alluvial (cassiterite) deposits in the Nigerian Younger Granite Region (NYGR) and the model performance assessed. We focused on the training and testing data split using longitudinal spatial data splitting (strips and halves) to ensure predictive attribute's independence. The spatial data split runs counter to the traditional random sample data selection as a procedure for checking overfitting of models mainly due to spatial data autocorrelation. Specifically, we used classification algorithms such as; Naive Bayes, Support Vector Machine, K-Nearest Neighbour, Decision Tree Bagging and Discriminant Analysis algorithms for training and testing. We analysed the model's performance results using model predictive accuracy and ROC curve values in two different approaches that improve spatial data independence among predictive attributes to give a meaningful model performance

Determination of entrance skin dose from diagnostic X-ray of human chest at Federal Medical Centre Keffi, Nigeria

patient during x-ray examination in Federal Medical Centre, Keffi in Nasarawa state, Nigeria. Entrance skin doses (ESDs) for a common type of x-ray procedures, namely chest AP/PA (anterior/posterior) were measured. A total of 200 data were collected from patients who were exposed to diagnostic X-ray during their routine chest X-ray examinations. The age of the patients ranged from 15 to 68 years old while the weight and height of these patients ranged from 37.5kg to 98.5kg and 130.0cm to 175cm,  respectively. The patent’s skin dose were determined using Edmond’s formula, which is based on the X-ray tube and the radiographic exposure parameters of kVp, mAS, SSD and the total filtration of the beams. The calculated mean skin dose ranges from 0.013± 0.01mGy to 0.851±0.023mGy. In general, the ESDs measured for this type of x-ray procedures were found to be lower than or in agreement with the guidance level set by the Nigerian Basic Ionizing Radiation Regulation (NBIRR, 2003) standard and other international bodies and does not pose any significant health risk to the patience or the workers.Keywords: Entrance skin Dose, X-ray, Anterior-Posterior, Exposure, and Radiation

Microbiological Assay of Two Selected Products of Ceftriaxone Powder for Injection from Pharmaceuticals' Market in Sudan

Background: Different techniques have classically been used to evaluate and assure the quality of medicines circulated on the market; one of the commonly uses is chemical analysis. However, some evidence has shown that there are other important indicators (e.g. bioequivalence, relative potency, etc.) that should also be considered when evaluating the quality of pharmaceutical products.Materials and Methods: A microbiological assay was conducted to compare the relative potency of two Ceftriaxone products (with a third one used as standard product) from the market using 3 reference bacteria including Streptococcus pneumoniae, Klebsiella pneumoniae and Staphylococcus aureus. Serial dilutions were made with the corresponding 1, 4, 8, 16 and 32-fold Minimum Inhibitory Concentration (MIC) of Ceftriaxone against the bacteria under investigation.Results: The relative potency of one product compared to the standard product was estimated to be within the acceptable range of bioequivalence (89.6%), while the other product showed unacceptable relative potency (72.3%).Conclusions: The microbiological assay is an effective and simple method for comparing the equivalency of injectable products. A complaint reporting system about quality and effectiveness problems needs to be considered as a priority source of such information to inform decision-makers.Keywords: Microbiological assay, Ceftriaxone, quality assurance, relative potency and genericmedicines

Removal of Congo Red Dye from Aqueous Solution using Sugarcane Bagasse and Bambara Groundnut Shell

A methodology involving sugarcane bagasse (SB) and Bambara groundnut shell (BGS) as adsorbents was developed in order to remove the carcinogenic Congo red dye from aqueous medium. The effect of contact time, sorbent dosage, initial concentration and pΗ were investigated. The results showed high efficiency of ≈ 93% and 75% using 4.5g of SB and BGS respectively. The results also indicated that the % removal increases with increase in dye loading concentration, while it decreased with an increase in pΗ of the solution from 4 to 10. From the results, it is possible to conclude that sugarcane bagasse and Bambara groundnut shell are good adsorbents for dye effluent treatment.Keywords: Bambara groundnut shell, Congo red, Sugarcane Bagasse, % Dye Removal

A study on Prevalence of Drug Resistance in Drug Default Pulmonary Tuberculosis

Background: The emergence of resistance to drugs used to treat tuberculosis (TB), and particularly multidrug-resistant TB (MDR-TB), has become a significant public health problem in a number of countries and an obstacle to effective global TB control.Method: This is a prospective randomized cross sectional study to estimate the magnitude of MDR tuberculosis in two hospitals in Khartoum, Sudan. 111 patients who had defaulted their tuberculosis treatment on previous occasions and had presented to the hospital with several symptoms were studied. All patients provided sputum, which was examined for the presence of acid fast bacilli (AFB) by Ziehl- Neelsen stain. Sputa were also sent to the reference laboratory for mycobacterial culture and drug susceptibility testing. All culture positive sputa had drug sensitivity tested to the first line anti-TB drugs used in Sudan namely Streptomycin, Isoniazid, Rifampicin and Ethambutol.Results: Out of the 111 patients, 29.7% (n=33) were AFB sputum smear positive and 40.5% (n=45) were sputum culture positive for  mycobacterium. Sensitivity testing revealed that 48.9% (n=22) were resistant to Streptomycin, 62.2% (n=28) were resistant to Isoniazid, 55.6% (n=25) were resistant to Rifampicin and 37.8% (n=17) were resistantto Ethambutol. 42% ( n=19) of the patients were resistant to Rifampicin and Isoniazid only, while 26.6% (n=12) were resistant to all the first line drugs (Streptomycin, Isoniazid, Rifampicin and Ethambutol).Conclusion: This study showed that the prevalence of MDR tuberculosis among the defaulters in Khartoum is much higher than what was reported previously. This study highlights the extent of the problem of drug resistance in Khartoum and emphasises the need for proper treatment andstrengthening of the short course direct observed therapy strategy

Strategi Penghidupan Berkelanjutan Masyarakat Sekitar Amal Usaha Muhammadiyah Pada Masa Covid 19 Di Taliwang Sumbawa Barat

berbagai strategi pemerintah, Lembaga/swasta dan masyarakat dalam mempertahankan kehidupan dimasa Covid-19. Strategi penghidupan masyarakat Desa Seloto sebagai pusat perkembangan Amal Usaha Muhammadiyah (AUM) di Kabupaten Sumbawa Barat. Memiliki strategi penghidupan masyarakat beragam di sekitarnya. Penelitian ini bertujuan untuk mengkaji strategi penghidupan berkelanjutan masyarakat sekitar Amal Usaha Muhammadiyah pada masa covid 19 di Taliwang Sumbawa Barat. Metode yang digunakan dalam penelitian ini adalah deskriptif. Hasil dari penelitian ini menunjukan bahwa strategi pertama,  strategi intensifikasi, pada masa Covid-19 tertinggi terdapat di Dusun Brang Pandan dan Brang Bulu rata-rata mencapai 18,15 dan paling rendah di miliki pada Dusun Brang Late mencapai 37,47. Srategi Kedua, strategi diversifikasi, pada masa Covid-19 tertinggi terdapat di Dusun Lenang Late rata-rata mencapai 18,15 dan paling rendah di miliki pada Dusun Brang Bulu  mencapai 13,30. Dan Strategi ketiga, strategi migrasi pada masa Covid-19 sama-sama dari ketiga dusun tersebut rata-rata rendah mencapai 2. Berbagai strategi dilakukan dalam meningkatkan kehidupan masyarakat masa Covid-19, namun aksi nyata terutama meningkatkan kehidupan yang lebih baik masa dan pasca Covid-19