Phase-Locked Loop Control In Low-Inertia Grid-Connected Voltage-Source Converters

As the integration of renewable energy on the grid increases, the number of voltage-source converters (VSC) installed also does. VSC controls both switch turn-on and turn-off, allowing a dc voltage source to be switched between phases. For the converter to accurately synchronize with the grid, a phase-locked loop (PLL) is used for the frequency measurements of the grid. However, the implementation of PLL with measurement delay introduces harmonics, noise, high frequency, and voltage oscillation to the system due to its dynamics. The dynamics introduced to the grid can be ignored under stiff grid conditions, but power from renewable sources decreases the grid inertia creating a weak-grid condition. Older grids accommodate this by using generators that compensate for the rate of change of frequency (RoCoF). Modern grids have less generator to accommodate the RoCoF, so there is a desideratum to implore a robust controller that responds quickly to the RoCoF, disturbance/ distortion rejection, and noise immunity to the grid. In recent literature, the effect of the PLL dynamics on a weak grid has been of great concern because of its unmodeled dynamics that destabilizes the converter under the weak-grid condition. This thesis proposes showing the impact of the weak-grid on the VSC as the dynamic of the grid changes. It also provides remedies to the grid instability and high-power injection levels. The detailed PLL dynamics model, including the ac-bus voltage dynamics with constant frequency, is developed and linearized. Even at a fixed frequency, various factors play a role in grid instability, and this tremendously affects the ability of the VSC to control the grid efficiently. The effect of the PLL gain under the weak-grid condition is analyzed

Collective Bargaining and Dispute Settlement in the Food, Beverage and Tobacco Industry in Lagos State, Nigeria

This paper examines collective bargaining and dispute settlement in the Food, Beverage and Tobacco Industry in Lagos State, Nigeria. Collective bargaining as one of the processes of industrial relations performs a variety of functions in workplace relations. It could be viewed as a means of industrial jurisprudence (rule making process in industry) as well as a form of industrial democracy. It is also a means for resolving workplace conflict between labour and management as well as the determination of terms and conditions of employment. Industrial disputes are inevitable in the Food, Beverage and Tobacco Industry. Industrial or trade disputes have both costs and benefits to the three social partners and the society at large. These social partners are the government, labour and management. However, it should be noted that from experience the costs of industrial disputes have always outweighed the benefits. Trade disputes as exemplified by strikes, to a large extent have a great bearing on the smooth and orderly development of the economy and the maintenance of law and order in the society. Thus, because of the adverse implications of industrial disputes, affected parties often seek speedy settlement of such disputes whenever they arise. The grievance procedure forms part of the procedural agreement of the collective bargaining agreement, which deals with such matters as the methods to be used and the stages to be followed in the settlement of disputes in the workplace. However, the grievance procedure is limited for use within the organisation. In the event that this procedure fails to settle the issue at dispute, then the parties can resort to the external machinery as provided by public policy as exemplified by mediation, conciliation, arbitration and the National Industrial Court (NIC). The existing statutory machinery for the settlement of disputes has not been effective in terms of delays experienced by aggrieved parties as well as cumbersomeness of the procedure. Oftentimes, judgements drag on for years and justice delayed is justice denied. More so, the statutory dispute settlement procedure has not fostered industrial harmony to a large extent. From the foregoing, it is recommended that the adoption of collective bargaining and Alternative Dispute Resolution (ADR) should be given due consideration by the parties in the Food, Beverage and Tobacco Industry to settle industrial disputes whenever they arise. Keywords: Collective Bargaining, Dispute, Settlement, Food, Beverage and Tobacco Industry

Permanent Voters Card (PVC) not Automated Teller Machine (ATM) the Problem of Cash and Carry Politics in Nigeria: What Role for the Media?

Anecdotal evidence has demonstrated that vote buying and selling remain a humongous challenge towards empowering the right people who can properly steer the affairs of any country. In other words, the above statement underscores the fact that when electorates sell their fundamental rights to bring to power the right leaders who ensure good governance, they consequently suffer from the outcome of such mistake. Put differently, when voters who could use their permanent voters card to choose the right people into the government decide to exchange their votes for cash, they end up suffering the consequences of such wrong decision. Vote buying or what this study refers to as "cash and carry politics" has remained an issue of great concern in recent time. Sadly, from 1999 till date, studies have shown that most candidates, both in primary and general elections have been implicated in vote-buying. According to reports, delegates in the recently concluded 2022 primary elections were paid as much as $9000 by the two political parties, (APC and PDP) to persuade them to vote for certain candidates. This type of situation no doubt spells immense doom to the survival of democracy and enthronement of the good governance in Nigeria, the reason being that he who pays the highest dollars apparently gets the highest votes. It is against the foregoing that this paper examines the subject of votebuying in Nigeria and the challenges it has posed to the survival of Nigeria's democracy. The paper also explores the theoretical trajectories of vote-buying in Nigeria and expansively provides not only insights, but probable ways that the Nigerian media can lend their voice towards addressing this problem

Morphological, phytochemical and molecular characterization of five common Jatropha species in the Niger Delta Region of Nigeria

The economic and medicinal important genus Jatropha contains many distinctly different species. To elucidate the genetic relationship of five common occurring Jatropha species namely J. multifida, J. podagrica, J.tanjorernsis, J. curcas, and J. gossypifolia, thirty-nine morphological, six phytochemical features and one arbitrary marker was used to screen and explore their similarity. Morphological data was obtained from the measurement of vegetative and reproductive parts while the presence of five phytochemicals was determined using differentphytochemical tests. The DNA of all five Jatropha species were amplified and sequenced using Ribolose 1, 5- biphosphate carboxylase molecular marker. The DNA sequences were then aligned using the Basic Local Alignment Search Tool for nucleotide 2.8.0 version of the National Center for Biotechnology Information database and phylogenetic trees were constructed using Paleontological Statistical software and Molecular Evolutionary Genetics Analysis version 7.0.26 software. From the results of the classical and phylogenetic cluster analysis, the five Jatropha species was separated into two major clusters. The highly distinctive J. gossypifolia was the only species that clustered separately from the other Jatropha species. Although, J. tanjorensis has been reported to be a hybrid from J. curcas and J. gossypifolia, the species did not segregate and cluster with these species, but segregated with J. multifida, and J.podagrica, indicating that this species is more closely related to J. multifida, and J. podagrica than J. curcas and J.gossypifolia. The result therefore provide information that would be useful in the plant improvement programs for the genus Jatropha

The Internet, Freedom of Expression and Online Readers’ Attention to and Utilization of Online Newspapers’ Comment Sections

There is speculation that the exposure of the contents of online newspapers satisfies readers’ need for information and slows down the drive for the print versions. This study examined readers’ motivations towards reading online newspapers and whether they commented after reading. The study employed descriptive survey method in which questionnaire was administered to a randomly selected sample of 400 online newspaper readers. The findings demonstrated a high overall motivation level of the readers towards reading online version of newspapers. A further analysis of the findings revealed that readers were motivated to read online versions of newspapers because they had access to the internet. Also, readers were motivated to read online versions of newspapers because theyare interactive and provided timely updates. The study concluded that online newspapers were gaining popularity in the newspaper industry. Therefore, newspaper publishers should strategize ways to fully regulate and moderate online discussions on online newspapers’ comment sections. Keyword: Internet, freedom of expression, online readers, newspaper comment section DOI: 10.7176/NMMC/81-07 Publication date:June 30th 2019

Factors affecting stakeholders’ preferences for cowpea grains in selected parts of Nigeria

Cowpea (Vigna unguiculata L.Walp) is an important food security crop. It provides food and income for many small-holder farmers in Africa. As a food source, the grains contain large quantities of protein, carbohydrates, vitamins, and fiber. In spite of the high nutritional value of cowpea, the crop is underutilized in most households and commercial eating houses in Nigeria. Several factors have been reported as constraints affecting the consumption and utilization of the crop in Nigeria, but have not been documented. This research was conducted to identify the factors affecting the utilization of the crop and determine the stakeholders’ preferences that will increase the demand and consumption of cowpea grains in Nigeria. The study was carried out in Ibadan in Oyo State and Zaria in Kaduna State in Nigeria, with a total of 318 respondents. A descriptive research design was used to collect data which were analyzed using Statistical Package for Social Science (SPSS) IBM version 20 and Microsoft Excel spread sheet. From the social demography result, the respondents were from six different category of stakeholders in the cowpea value chain mainly from breeders (3.7%), farmers (36.0%), marketers (12.7%), food vendors (6.7%), nutritionists (2.6%) and consumers (38.9%). This implies that the respondents were knowledgeable about the factors affecting the cowpea utilization. The two factors identified to affect the utilization of cowpea were culinary qualities (63.0% of respondents) and removing dirt (37.0% of respondents). Among the culinary qualities, the major quality preferred was reducing the cooking time (42.9% of respondents), followed by improved taste (31.7% of respondents), and value added products such as cowpea in powdered form (19.0% of respondents), and canned cowpea (6.4% of respondents). A total of 47.2% of respondents preferred the duration for cooking cowpea for 21-30 minutes as against the 40-60 minutes most cowpea varieties cook for.  These findings indicate that cooking time is still the major factor affecting the utilization of cowpea grains. Therefore, improving this quality and other utilization attributes will increase the demand and consumption of cowpea grains

Adaptive Capacity of two Varieties of Groundnut (Arachis hypogaea L.) in Crude Oil Polluted Soil

Arachis hypogaea L. (Groundnut) production in Niger Delta, Nigeria is limited as the crop has not been well adapted to this region. This research was carried out to determine the adaptive capability of groundnut in crude oil polluted soil. Seeds of two varieties (Java and Bold Type) were planted in soil polluted with 0.8% and 0% of crude oil. Growth parameters were measured every 10 days up to 50 days after planting. Nodules were isolated from the roots 50 days after planting and cultured in YEMA solid medium and further subcultured in PDA medium to obtain pure cultures. Result showed that they adapted to the crude oil polluted soil with Java variety having the optimum agronomic performance, root architecture and rhizobium population. Nodules formed from day 10 to day 50 after planting shows that the highest number of nodules formation occurred on day 50 for the Java variety in polluted soil (32 nodules) while the bold variety had the lowest (5 nodules). Four fungal organisms identified in the pure-cultures were penicillium chrysogenum, Aspergillus niger, Mucor circinelloides, Botrydiplodia theobromae.  This research suggested that the ability of groundnut to grow in crude oil polluted soil could be due to their root architecture and ability to fix nitrogen in the soil. Further adaptation studies should be carried out covering other part of Niger Delta region. Keywords: Groundnut, Nodule, Adaptive Capacity DOI: 10.7176/JBAH/13-4-06 Publication date:March 31st 202

Health Risk Communication and The Hazards of Portable Electricity Generator Use: A Study of Awareness and Knowledge of Carbon Monoxide Poisoning Among Resident Nigerian Public University Students

The overall objective of the study was to determine Nigerian university students’ awareness and exposure to label warnings on portable electric power generators; their level of comprehension of these label warnings; knowledge of carbon monoxide poisoning; and, preventive measures taken to avoid carbon monoxide poisoning. The survey research method was used for this study. Data was collected in Southeastern Nigeria among undergraduate students, by administering questionnaire to a sample of 400 students from four universities. The study found a high level of exposure to label warnings on house hold products but a minimal exposure to label warnings on portable electric power generating sets among these students.Variables like placement of the warnings, font sizes and religious inclination hindered exposure to the warnings and compliance to the warning message; awareness of carbon monoxide information was high and a greater number among the respondents got informed either through their families and friends or read about it; a relatively lower number got informed through the media. While these university students were aware of carbon monoxide poisoning, they were not properly informed of the different symptoms that are associated with the gas and the preventive measures that could prevent carbon monoxide poisoning. This suggests that carbon monoxide poisoning is not being taken seriously as a health hazard among people susceptible to poisoning. Key words: Health risk communication, portable electricity generator use, carbon monoxide poisoning, label warnings DOI: 10.7176/JEES/9-6-14 Publication date:June 30th 201