569 research outputs found

    Air ion concentration under overhead high-voltage transmission lines

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    This paper reports air ion concentration monitored at 41 sites under overhead high voltage ac power lines in and around an urban environment. The net ionic polarity under power lines was of both signs but mostly positive, and concentrations varied widely from 0 to 3300 ions cm-3. Concomitant measurements of the vertical dc electric field at the ground confirmed the presence of a net positive charge above. Approximately 19% of the sites exhibited relatively high ion concentrations exceeding 1000 cm-3. The mean value of all the sites was 776 cm-3. Statistically, the mean for the transmission voltage (220-330 kV) line sites was significantly higher than that for the sub-transmission voltage (110-132 kV) line sites with means of 905 and 501 cm-3 respectively. These values were compared with the mean urban outdoor concentration well away from the lines which was about 400 cm-3 and of negative polarity. Overall, ion concentrations at approximately 76% of the power line sites exceeded the absolute mean urban outdoor value. The dc electric fields under the power lines showed a statistically significant relationship to the measured ion concentrations, although there was considerable scatter to indicate that electric field measurements do not necessarily reflect air ion concentrations at ground level

    Application of aerosol electrometer for ambient particle charge measurements

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    The charge on ambient atmospheric particles is an important parameter in the investigation of particle dynamics. Yet, there is only limited knowledge available on it, mainly due to the lack of instrumentation for its direct measurement. The aim of this study was to explore the application and suitability of the Aerosol Electrometer (AE) TSI Model 3068 as a direct instrument for measuring ambient particle charge concentration, thereby extending its use beyond the current applications. Through a set of experimental investigations the AE was applied to measure net concentration of charged particles in different environments. Results of the study showed the instrument is mostly suitable for outdoor field measurement, when particle charge concentrations are elevated, such as in the vicinity of strong ion emitting sources (high voltage powerlines, electricity substations, etc); and under conditions of air relative humidity of below 60%. Operating the instrument above this humidity value would require the use of a dehumidifier. 74% (R2) statistical correlation (P<0.05) was obtained between the readings of the AE and the Air Ion Counter, when both instruments were used to simultaneously sample ambient air

    Renegotiation of public private partnership road contracts: Issues and outcomes

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    The renegotiation of road projects has been an important issue that has generated concerns in PPP procurement over the last decade. This has had serious policy implications for public procurement policy across countries because of its implications for the achievement of the objectives defined at the inception of PPP road contracts. This paper assesses the renegotiation of Public-Private Partnership (PPP) infrastructure projects in order to identify the issues involved in renegotiation and its outcomes. Data were collected through a literature review of selected studies on PPP infrastructure projects on a sectoral basis with particular emphasis on Latin America, Portugal and Spain. It was revealed that a high proportion of PPP contracts in the transport sector are renegotiated: Indeed, in the transport sector, more PPP road projects are renegotiated than other forms of transport projects. The main factors surrounding the renegotiation of road contracts are: lack of an adequate contract design, frequent opportunistic behaviour on the part of both public and private partners during the implementation of PPP road projects, changes in the conditions affecting revenue and costs beyond the reasonable assumptions accounted for in the original contract, corruption, and political and economic instability, all of which in most instances reduce the chance of the public partner achieving its objective of value for money (VfM). The paper concludes with a discussion of the need to develop a framework for integrating considerations of value for money into the renegotiation process of PPP road contracts

    Investigating the Predictors of E-commerce Adoption: the Mediating Role of Customers’ Affective Responses

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    Extended abstract from Faculty of Business and Law Research Day 202

    Assessment Of Policies, Determinants And Characteristics Of Generic Medicines Entry Into The Malaysian Pharmaceutical Market

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    The Malaysia healthcare system relies on the availability of generic equivalents of innovator medicines to curtail the rising pharmaceutical expenditure. This study assesses the dimensions and dynamics of generic medicines entry following patent expiration on the innovator drug products in Malaysia. This was a mixed-methods study. The findings of this research revealed 14 categories of policies and regulatory measures with varying effects on generic entry in Malaysia. The mail survey yielded a usable response rate of 53.8% (14/26) following four successive mailings. Reliability coefficients for the multi-item entry decisions and entry barriers variables were 0.62 and 0.82 respectively. The major factors driving generic development and entry decisions in Malaysia were pre-patent expiration market value of innovator’s products (Meanrank= 3.75, M=4.14, SD=1.03), cost of generic development and approval (Mean-rank= 3.04, M=3.50, SD=1.40) and compatibility of the new generic medicine with firms’ existing products range (Mean-rank=2.79, M=3.64, SD=1.2). The innovator product’s pre-patent expiration market value was a significant entry driver for domestic-market oriented generic firms as compared with export-market oriented firms (U=0.00, Z=- 2.36, p=0.01). The Major barriers to generic medicines development and market entry in Malaysia were patent clustering by innovator firms (Mean-rank=7.96, M=4.07, SD=0.83) and earlier market entry of imported generics (Mean-rank=7.75, M=4.07, SD=0.73)

    Heuristics for Lagrangian Relaxation Formulations for the Unit Commitment Problem

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    The expansion of distributed energy resources (DER), demand response (DR), and virtual bidding in many power systems and energy markets are creating new challenges for unit commitment (UC) and economic dispatch (ED) techniques. Instead of a small number of traditionally large generators, the power system resource mix is moving to one with a high percentage of a large number of small units. These can increase the number of similar or identical units, leading to chattering (switching back and forth among committed units between iterations). This research investigates alternative and scalable ways of increasing the high penetration of these resources. First, the mathematical formulations for UC and ED models are reviewed. Then a new heuristic is proposed that takes advantage of the incremental nature of Lagrangian relaxation (LR). The heuristic linearizes and distributes the network transmission losses to appropriately penalize line flow and mitigate losses. Second, a mixed integer programming (MIP) is used as a benchmark for the proposed LR formulation. The impact of similar and identical units on the solution quality and simulation run time of UC and ED was investigated using the proposed formulation. Third, a system flexibility study is done using DR and a load demand pattern with a high penetration of renewables, creating a high daily ramp rate requirement. This work investigates the impact of available DR on spikes in locational marginal pricing (LMP). Fourth, two studies are done on improving LR computational efficiency. The first proposes a heuristic that focuses on trade-offs between solution quality and simulation run time. The heuristic iterates over lambda and energy marginal price while the convergence issue is handled using Augmented LR (ALR). The second study proposes a heuristic that penalizes transmission lines with binding line limits. The proposed method can reduce power flow in the transmission lines of interest, and considerably reduce the simulation time in optimization problems with a high number of transmission constraints. Finally, the effect of a large number of similar and identical units on simulation run time is considered. The proposed formulation scales linearly with the increase in system size

    Micrometrics and Morphological Properties of Starch

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    Starch occurs in form of granules and constitutes a primary manner in which of carbohydrates are stored chiefly in seeds and underground organs and sparingly in other morphological parts such as leaf and bark parts of plants. Grains of transitional starch can be found in the stroma of chloroplast and cytoplasm in leaf parts when exposed to the sun and transferred to organs for storage at dark times. The shape and size, ratio of amylose and amylopectin content of starch grains are peculiar to different biological sources. A literature survey was carried out using various search engines. Journals were searched for using keywords such as microscopy, amylopectin, starch granules etc. The relative qualitative and quantitative properties of starches from various morphological parts of 35 species from 15 families were studied. The qualitative features of shape and size as observed from microscopy were not specific or peculiar to each genus and family as similar shapes and sizes cut across different species. Amylopectin and amylose contents varied considerably among all the species and can be used as one of the means of identification for medicinal plants and the delineation of plant species along with other genetic and physicochemical properties

    Predicting the Market Share of a New Airport in Multi-Airport Cities: the Case of Lagos

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    The primary objective of the study was to develop an empirical model that combines the contingent valuation method (CVM) with the isochrone analysis to predict the market shares of new airports in multi-airport cities and to apply the model to the case of Lekki International Airport (LIA), the proposed second airport in Lagos, Nigeria. In addition to predicting the market share that LIA could attain, the study also identified and analyzed the catchment areas as well as the willingness to pay (WTP) of would-be LIA passengers. Furthermore, the research identified the determinants of airport choice in the Nigerian market. The CVM was used for the collection of the data; 1,176 valid in-person interviews were conducted at Murtala Mohammed International Airport (MMIA), Lagos. Descriptive statistics and logistic regression analysis were used to predict LIA’s market share and identify the factors that influenced passengers’ choice between the existing and the proposed second airport. Further, isochrones and passenger stated preference data were analyzed for the determination of the LIA’s catchment areas for the business and non-business segments of the Nigerian market as well as the areas of spatial competition between MMIA and LIA. With regard to the passengers’ willingness to pay, the median of the WTP values was determined through descriptive statistics. The determinants of the WTP were also identified using a multiple regression analysis. Using the combination of CVM and isochrone analysis, the present research predicted that LIA will attain 28.9% of the market share based on the contingent scenario presented to the passengers. Further, the study found that the exclusive catchment areas of LIA for business and non-business passengers were limited to two Local Government Areas (LGAs) of Lagos State. Passengers who chose LIA as their first choice were willing to pay NGN3000 (about $15 or 15% of an average domestic one-way ticket price) as additional fare to fly from the airport. However, the realization of the predicted market share will be contingent on LIA’s ability to attract airlines, remedy the isolation of the proposed airport site, and apply the appropriate pricing policy

    Exploring the place of troubleshooting in an undergraduate electronics engineering education programme at a university in South Africa.

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    Doctoral Degree. University of KwaZulu-Natal, Durban.Whereas the ability to identify, formulate and solve engineering problems is considered an essential learning outcome for an engineering education curriculum, there seems to be ambivalence around the place of troubleshooting in electronics engineering programmes. Yet, the practice of troubleshooting is deemed a requisite generic engineering competency skill in industry. The San Diego 24-hour blackout in 2011 is a commonly cited case to highlight the importance of electronics troubleshooting in modern electronics engineering. In this regard, engineering troubleshooting is seen to play a vital role in the safety and economic wellbeing of a nation. However, many universities offering engineering education programmes have tended to omit or put little emphasis on troubleshooting in their curriculum, thereby creating a lacuna between theoretical knowledge and problem solving skills in real-world troubleshooting. This current study, therefore, sought to explore the place of troubleshooting in an undergraduate electronics engineering education programme at a South African university. This study argues that, without the appropriate instructional pedagogy in troubleshooting, a tension between “theory” and “practice” in engineering education will continue to exist. A qualitative case study research design was employed to interrogate the following three broad questions: (i) Is troubleshooting accommodated within an electronics engineering programme? (ii) How is the electronics engineering programme enacted? (iii) What informs how the programme was enacted? Phenomenography and Lefebvre’s theory of space were used as analytical and theoretical frameworks, respectively. Phenomenography allowed for the delineation of the different ways in which troubleshooting was conceptualised by the various participants. Lefebvre’s theory of space allowed for the differentiation of the three domains that characterise the place of troubleshooting within the undergraduate electronics engineering programme, namely, the conceived space (government policy), the perceived space (institutional curriculum and instruction) and the lived space (fourth year engineering students). With respect to the first question, the findings revealed that this question was domain dependent. With respect to the first domain, the findings indicate that troubleshooting was not afforded any place at all (0% affordance), whereas the second domain showed a mixed response from the participants (lecturers and technicians). A 50% versus 50% affordance was recorded for this domain. In contrast, the third domain’s findings indicated 100% affordance. With respect to the second question, the findings were that the electronics engineering programme was broadly enacted through individual-based, theory-based and design-based practices, indicating a total absence of explicit troubleshooting teaching practices. Further, findings from the third question reveal that there was no explicit teaching of troubleshooting in the electronics engineering education programme. While the practice of troubleshooting is deemed a requisite generic engineering competency skill, the non-explicit teaching of troubleshooting as a core part of electronics engineering curriculum has implications for policy, practice and research. Whereas the CHE and ECSA policy documents that guide engineering education in South African universities make no provisions for the place of troubleshooting in electronics engineering education programme, the findings suggests that such omission or silence in the policy impacts the learning outcome of electronics engineering students, who graduate without the requisite expertise needed to solve real-life troubleshooting problems. This requisite expertise, as the literature affirms, should unequivocally form an important element of the electronics engineering curriculum practice and discourse in South African universities. The implications of the findings in this study further suggest the need to critically look at the possible gaps between theory and practice, and the dynamics of institutional influences on practices. Further research is suggested with a view to narrow the gap between theory and enactment in the electronics engineering education curriculum

    Defense in Depth Network Perimeter Security

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    Defense in depth network perimeter security has always be a topic of discussion for a long time as an efficient way of mitigating cyber-attacks. While there are no 100% mitigating method against cyber-attacks, a layered defense in depth network perimeter security can be used to mitigate against cyber-attacks. Research have shown a massive growth in cyber-crimes and there are limited number of cyber security expert to counter this attacks. EIU as an institution is taking up the responsibility of producing cyber security graduates with the new Master of Science in Cyber Security program that started in Fall 2017. This research is aim at designing and developing a defense in depth network perimeter security that will be used for laboratory practices to learn and simulate cyber security activity and its mitigation. The research is complemented with the design of ten laboratory practices to give expertise to the students in the equipment used in the design. The designed topology comprises of two sites, connected via IPSec site to site VPN over an unsecure internet connection. A public testing webserver is placed at the DMZ which is to be used to invite hackers to attack the design system for the purpose of detecting, preventing and learning cyber-attack mechanisms
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