An Improved Differential Evolution Algorithm for Maritime Collision Avoidance Route Planning

High accuracy navigation and surveillance systems are pivotal to ensure efficient ship route planning and marine safety. Based on existing ship navigation and maritime collision prevention rules, an improved approach for collision avoidance route planning using a differential evolution algorithm was developed. Simulation results show that the algorithm is capable of significantly enhancing the optimized route over current methods. It has the potential to be used as a tool to generate optimal vessel routing in the presence of conflicts

Cobalt removal from wastewater using pine sawdust

Agricultural wastes can cause environmental problems if not well managed, but there is a lot of potential to use these wastes as raw material in other processes. In this investigation, pine sawdust was evaluated as an adsorbent in the treatment of wastewater containing cobalt ions. A two-level three-factor full-factorial experimental design with centre points was used to study the interactive effect of the operating parameters in order to achieve the best conditions for the batch adsorption of cobalt ions. A response surface analysis was also conducted to further understand the interactions amongst the factors such as adsorbent dose, solution pH and initial concentration. In addition, adsorption isotherms, namely the Freundlich and Langmuir, were used to characterize the removal of cobalt from the wastewater. It was observed that the combined effect of low adsorbent dose, high pH and high initial concentration of wastewater resulted in the highest adsorption capacity. The Freundlich isotherm provided a better fit to the experimental data than the Langmuir isotherm. Moreover, pine sawdust showed adsorption capabilities for cobalt, and hence it could be an option in the quest to use waste to treat wastewater

Mutual Authentication in Wimax Security using Diffie Hellman

Network security is becoming an area of concern with the expansion of wireless technology. Many businesses have lost a lot of money as a result of compromised network security. The Worldwide Interoperability for Microwave Access (WiMAX) is one example of 3G technology which is getting popular. Most business establishemnst use WiMAX to network their communication equipments. The popularity of WiMAX and its security vulnarability are the key motivation for this study. Presently, PKM versions of authentication are used to secure WiMAX networks. The PKM authentication methods expose the WiMAX network to third party risks like Man in the Middle attacks, eavesdropping and jamming attacks.  WiMAX is thus vulnerable to network attacks that compromise the radio links between the communicating Subscriber Station (SS) and the serving Base Station (BS). The PKMv1 process involves a one sided authentication. The BS authenticates the SS but the SS has no capacity to authenticate a BS. As a result, a rogue BS can successfully enter the network of a SS without prevention. The rogue BS can then tap all the unencrypted management messages. This constitutes a major security flaw. The Man-In- The-Middle (MITM) attack exploits this weakness in the network by eavesdropping, interception and fabrication of the management messages, resulting in a breach in the reliability of the entire network. In this research, a modification of the Diffie-Hellman (DH) key exchange protocol is used to mitigate the man-in-the middle attack in WiMAX by modeling using the Dev C++ programming language. The DH protocol uses a unique algorithm whose solution must be obtained by both the SS and the BS for communication to be allowed. Both the BS and the SS are given an opportunity to authenticate one another before any communication can proceed. Keywords: Diffie Hellman; Mutual Authentication; Security; WiMAX

Effective Microporosity for Enhanced Adsorption Capacity of Cr (VI) from Dilute Aqueous Solution: Isotherm and Kinetics

The adsorbent pore structure significant to enhanced adsorption capacity of Cr (VI) from dilute aqueous solution is evaluated. As reference, low-cost micro-mesoporous activated carbon (AC) of high basicity, mesoporosity centred about 2.4 nm, and effective microporosity centred about 0.9 nm was tested for removal of Cr (VI) from dilute aqueous solution in batch mode. At pH 2 the low-cost AC exhibited highly improved Langmuir Cr (VI) capacity of 115 mg/g which was competitive to high performance commercial AC. A Comparison with treated characterization results of literature adsorbents/ACs showed that moderate to high effective micropore volume of average pore-size about 0.9 ± 0.1 nm is critical for increased adsorption capacity of Cr (VI) from dilute aqueous solutions. The mesostructure of the tested low-cost AC was associated with rapid kinetics that was fitted by the Pseudo-second kinetics model. While Biot numbers suggested slight significant contribution of intraparticle diffusion. It is hoped that this study may be a useful contribution to development of effective adsorbents for the efficient abatement of toxic Cr (VI) from wastewater and water

Establishing the quality management baseline in the use of computed tomography machines in Kenya

The objective of this study was to assess the level of compliance to quality assurance and image quality standards in computed tomography facilities in Kenyan hospitals. A quality assurance inspection and physical image quality assessment in eighteen representative computed tomography facilities were completed. A quantitative method was developed and used to score the results obtained from the physical image quality measurements using the American Association of Physicists in Medicine (AAPM) water phantom. Inspection was done in order to establish the level of compliance with internationally recognized standards such as those stipulated in the European Guidelines Quality Criteria for Computed Tomography and the International Basic Safety Standards for Protection against Ionizing Radiation. The overall findings placed the national quality management performance at 50± 3%, while image quality and quality assurance performance were 61 ± 3% and 37 ± 3%, respectively. The quality assurance assessment benchmarked the country’s level of quality management system compliance in diagnostic radiology. During accreditation appraisal, the scrutiny of scores from each stage in the medical imaging chain per facility will encourage continual implementation of the quality improvement process

Efficacy of fecal fertilizers on growth, nutrient uptake and yield of maize

Maize (Zea mays L.) is the most widely cultivated staple food crop in sub-Saharan Africa. However, its production is severely constrained by abiotic and biotic factors of which declining soil fertility is a major contributor. A study was conducted to evaluate the efficacy of fecal matter based organic fertilizers on growth, nutrient uptake, yield and yield components of maize, in two distinct agro-ecological zones. Five fertilizer treatments (control, Diammonium Phosphate (DAP), cow manure, struvite, compost from fecal matter) were tested in a randomized complete block design (RCBD) with four replications per site. Data were collected on crop emergence (%), plant height, number of leaves per plant, leaf area index (LAI), tasseling (%), nutrient uptake and grain yield and yield components. Data were subjected to analysis of variance and treatment means separated using Tukey’s HSD test. Results showed that crop emergence in the control treatment, except for struvite, was significantly higher than DAP and fecal matter based organic fertilizer plots in Bahati and Lanet sites. The end-point plant height (9 WAP), LAI and tasseling were significantly (P<0.05) influenced by location and organic fertilizer treatments. At the Lanet site, DAP and struvite treatments equally had the tallest maize plants (163 cm) followed by fecal compost (128 cm), manure (121 cm), and the control (79 cm). Similar result trends were recorded in Bahati where struvite (193 cm) had the tallest plants followed by fecal compost (166 cm), DAP (155 cm), manure (151 cm) and the control (98 cm), respectively. A contrasting result was observed at the Egerton University site in which cow manure and the control plots equally had the tallest plants (117-121 cm), followed by DAP and fecal compost (98-99 cm), and struvite (91 cm). The LAI, tasseling and grain yield were significantly influenced by location with struvite and fecal compost treatments producing the highest grain yield (≈8 t/ha) and one thousand (1000)-seed weights (480-560 g) at the Egerton University and Bahati experimental sites. Nitrogen uptake by maize for organic fertilizer treatments was higher than the control at all three locations. However, there was no difference in uptake of phosphorous and potassium between control and organic fertilizer treatments. These findings have demonstrated the potential of fecal matter based organic fertilizers as alternatives to inorganic fertilizers in smallholder agriculture.Key words: Zea mays, fecal compost, struvite, nutrient uptake, manure, Nitrogen, Phosphorus, Potassiu

Determination of LDL-cholesterol: direct measurement by homogeneous assay versus Friedewald calculation among Makerere University undergraduate fasting students

The treatment of patients for coronary heart disease risk requires knowledge of the plasma lipid levels. Low density lipoprotein cholesterol (LDL) levels make a strong basis for therapeutic decisions. Although there are incongruities among values of LDL from different methods of determining LDL, the clinician is not routinely informed of the method used. The purpose of this study was to compare LDL levels determined by the Friedewald equation with those assayed by the Kyowa Madox method. The lipid results previously measured by Kyowa Madox method among Makerere University fasting students and reported earlier wereretrieved. The measured values of total cholesterol (TC), High Density Lipoprotein cholesterol (HDL) and triacylglycerols (TG) were used to calculate LDL using Friedewald equation in which LDL= TC-HDL-TG/2.2mmol/L. The values obtained were compared non parametrically with the assayed values previously reported. Our results showed a high value of correlation between measured and calculated LDL so that in general, the two methods can be used interchangeably in this population. However, in cases of dyslipidaemia, the calculated values tend to be lower than the assayed values. It is therefore recommended that clinical laboratories should report the LDL values along with the determination method used, the alert values, the reference ranges, the desirable ranges and the therapeutic targets. © 2010 International Formulae Group. All rights reserved.Keywords: Homogeneous assay, LDL cholesterol, direct measurement, Friedewald equation, comparison