316 research outputs found
Production of Mesophase Pitch from Gasified Lignin-Derived Tars
Lignin tars are created as a by-product of lignin gasification. Significant effort has gone into minimizing tar production. However, no process has been shown to completely eliminate its formation. As a result, the tar is being used to manufacture low value products such as asphalt, or is being used as a fuel in fixed combustion systems.
The research presented here is part of an effort to increase the viability of using lignocellulosic biomass as a feedstock to produce high value products. We tested the postulate that tars derived from lignin could be processed into a mesophase pitch allowable for conversion into high quality carbon fibers. Literature demonstrates that coal tar and petroleum pitch can be transformed into a high quality mesophase pitch. However, the processes involved are complicated and expensive. This is because the impurities - ash content for example, in these materials lead to defects in the pitch and must be removed. Since lignin is without these impurities, its transformation into mesophase pitch should be a less complicated and less expensive process than those for coal or petroleum analogs.
Tars were generated using a lab-scale gasification vessel, at an overall conversion rate of 16% tar from kraft lignin. The tar was subsequently filtered and fed to a residue pitching reactor. The pitching reactor was used to generate mesophase pitch under inert conditions. During the pitching step, an unexpected temperature increase likely due to partial oxidation of lignin carbon units with inherent oxygen released during the process was observed. Characterization of both the tar and pitch products was performed by thermogravemetric analysis and differential scanning calorimetry. Further characterization of the pitch products was performed using SEM.
A mixture of apparent coke and mesophase pitch products were produced in the pitching reactor. However, the TGA profiles of both products were very similar while their morphologies differed slightly. The condition of ~215°C with a vacuum pressure ranging from ~0.03-0.13 kPa was at the threshold of coke formation while allowing mesophase pitch formation for lignin tar. These results demonstrated that it is possible to generate a mesophase pitch from lignin-derived tars. However, further work is required to perfect the process such that a commercially viable pitch product is generated
Mitigating Turbulence-Induced Fading in Coherent FSO Links: An Adaptive Space-Time Code Approach
Free space optical communication systems have witnessed a significant rise in attention over the last half a decade owing largely to their enormous bandwidth and relative ease of deployment. Generally, free space optical communication systems differ in their detection mechanism as various detection mechanisms are being reported, including intensity modulation/direct detection FSO, differential FSO and coherent FSO. In this chapter, we explore the prospect of obtaining an optimally performing FSO system by harnessing the cutting-edge features of coherent FSO systems and the coding gain and diversity advantage offered by a four-state space-time trellis code (STTC) in order to combat turbulence-induced fading which has thus far beleaguered the performance of FSO systems. The initial outcomes of this technique are promising as a model for various visible light communication applications
Assessment of Rural Dwellers Satisfaction with Quality of Infrastructure in Rural Settlements of Niger State, Nigeria
This study evaluates the responses of rural dwellers to an aspect of their environment, the quality attributes of the infrastructure provided for their use. The quality attributes considered were derived from location, management, economic, environmental and physical qualities of the respective infrastructure namely health, education, water supply, electricity and road.To achieve this aim, a multi-stage sampling technique was employed to systematically select 22 rural settlements in 22 local government areas. In all, a total of 1,792 rural dwellers were selected. Chi-square (X2) was used to determine the relationships between the quality attributes and perceived level of satisfaction of the respondents in the study area. The findings revealed that the quality attributes of the infrastructure such as availability of personnel, drugs and equipment, distance to facilities, cost, regularity and maintenance of facilities as well as quality of infrastructure were perceived by the rural dwellers to be generally unsatisfactory. Chi-square analysis revealed that there exists significant relationship between perceived level of satisfaction and the entire infrastructure considered. The results of the chi-squire analysis are all significant at 5% level. It can therefore be concluded that the quality attributes of the facilities were generally perceived as unsatisfactory by the rural dwellers. The paper recommends regular monitoring and proper maintenance jointly by the providers and beneficiaries. Keywords: Satisfaction, Rural Dwellers, Infrastructure, Quality attributes, Transformation and Rural Settlements
Assistive Technology For Hearing and Speech Disorders
Many individuals with hearing loss will need rehabilitation in order to live maximally productive lives. As such, they need a variety of assistive technologies that provide them with improved access to information thereby enhancing their communication capabilities in a wide variety of environments. Most devices either provide sound amplification or alternate ways to access information through vision and /or vibration. These technologies can be grouped into three general categories. Within each main category, there are subcategories based on different purposes or the intended audiences when utilizing the technology. The overall goal of these devices is improved accessibility to information as close as possible to that enjoyed by individuals without speech and language disorders. The paper discusses the assistive technology for those with hearing impairment. Keywords: Assistive Listening Device, Hearing Technology, Alerting Devices, Communication Suppor
Current Trends in Audiological Practices and Implications for Developing Countries
This paper examines the current trends in audiological practices in Nigeria, as it makes case for compulsory use of electro- physiological tests in determining the hearing potentials of children in the country, as against the use of behavioural audiometric strategy which requires the active participation of the patients. Varieties of electro- physiological tests such as Auditory Brainstem Response Test (ABR), Oto- Acoustic Emission, and modern advances such as cochlear implants and auditory brainstem implants for Neuro- Fibromatosis type 2 (NF2) as practiced in developed countries were explained. These current trends in audiological practices should serve as a catalyst to stimulate the developing countries in managing hearing and speech disorders. Keywords: Audiological practices, Developing countries, Audiological investigations, Audiological Managemen
Comparison of Academic Achievement between Students with Congenital and Acquired Deafness in a Nigerian College
Background:-Most students with deafness have some difficulty with academic achievement, especially with reading and mathematics. However, the range of intelligence levels of students with deafness does not differ from the range in their hearing counterparts. Academic performance must not be equated with intelligence. Most children who are deaf have normal intellectual capacity and it has been repeatedly demonstrated that their scores on non-verbal intelligence tests are approximately the same as those of the general population. Deafness imposes no limitations on the cognitive capabilities of individuals. The problems that deaf students often experience in academics and adjustment may be largely attributed to a bad fit between their perceptual abilities and the demands of spoken and written English. Several studies have suggested that one of the most potent predictors of academic achievement for the students with deafness is the amount of personalized and specialized attention they receive. Objective:- The objective of this study was to investigate the presence of differences between the academic achievement of students with congenital and that of students with acquired deafness. Methods:- Fifty students with deafness (twenty-five students with congenital deafness and twenty-five students with acquired deafness) were studied ex-post facto. All fifty students were of the same educational level at the Federal College of Education (Special) Oyo, Nigeria. The instruments used were teacher-made achievement test and subjects academic records on English and Mathematics. The teacher-made achievement test was tested valid with the use of Kuder-Richardson (KR-21), which indicated an alpha level of 0.62. Result:- There was no significant difference in the academic achievement (t = 2.00, p=0.973) in mathematics performance (t = 2.00, p=0.765) or in English Language performance (t= 2.00, p=0.680) between students with congenital deafness and those with acquired deafness. Conclusion: Academic achievement is comparable among non-mentally retarded deaf students who are undergoing proper rehabilitation irrespective of whether the deafness was congenital or acquired Keywords- Academic achievement, Congenital deafness, Acquired deafness, Nigerian colleg
Hearing Loss and the Elderly - A Primer
Hearing impairment, is very common among the elderly. In many of them it can be so disabling that it affects normal day to day activities, impairs communication and puts them at risk of social isolation and psychological problems. Fortunately, while it cannot be reversed most times, hearing loss in the elderly can be so well managed that the elderly can enjoy a good quality of life. This article is a review on presbycusis (age-related hearing loss), the physiology and management as a means of sensitizing medical personnel and those working with the elderly
Impact of Prepaid Energy Metering System on the Electricity Consumption in Ogbomoso South Local Government Area of Oyo State
Electricity is one of the basic requirements for people and they are widely used for domestic, industrial and agricultural purposes. Every meter is a device that measures the amount of electrical energy consumed by a residence, business or an electrically powered device. This paper presents the impact of prepaid energy metering system on electricity consumption in Ogbomoso South Local Government Area of Oyo state. The results of the paper revealed that about 95% of the pre-paid meter users in the local government area are conscious of electricity management, about 74% of the post-paid meter users were just wasting the energy. The introduction of the pre-paid metering system has increased the revenue collection and hence, reduced the revenue generation of the local government area because of the reliability nature of the metering system. The pre-paid metering system has created a positive impact on the electricity consumption as well as the increment in the price tariff of the electricity. Keywords: Energy metering system, Electricity consumption, Post-paid metering system, Pre-paid metering system, Solid state electronic meters (SSEM)
Impact of Embedded Generation on Power Distribution System Voltage Collapse
The term “embedded generation”(EG) refers to electricity generation connected at distribution level rather than transmission level. E.G. can reduce the effect of losses while providing reactive power and contingency reserves to the network. It can also reduce the need for new transmission and distribution facilities consequently reducing overall costs. A distribution system is the system of an overall power system which links the bulk system to the individual customers. Voltage stability is an important performance index which defines the quality of supply. This paper presents the impact of embedded generation (EG) on power distribution system voltage collapse. ABUAD is considered as a case study in the research paper. The voltage stability indices (VSI) are calculated and assessed. The distribution network is reconfigured and the new values of VSI were computed to analyze the optimum configuration. The result of the paper showed that after thee reconfiguration of the system network the maximum KW, KVAR and KVA connected loads on the four selected transformers have increased by 9.11%, 9.04% and 8.44% respectively. The VSI for transformer T1 has increased from 0.0035 to 0.00362 while the VSI for transform T2 also decreased from 0.003845 to 0.0037 after the network reconfiguration. The VSI for transformer T3 and T4 remained constant even after the system network has been modified. The distribution system can be optimized for improved performance indices of which voltage stability is significant. Keywords: Embedded Generation, Voltages Collapse, Stability Index, Distribution Networks, Reconfiguration, Improved Performance, Transformers
Evaluation of Simultaneous Equation Techniques in the Presence of Misspecification Error: A Monte Carlo Approach
One of the assumptions of Classical Linear Regression Model (CLRMA), is that the regression model be ‘correctly’ specified. If the model is not ‘correctly’ specified, the problem of model misspecification error arises. The objective of the study is to know the performances of the estimator and also the estimator that is greatly affected by misspecification error due to omission of relevant explanatory variable. Four simultaneous equation techniques (OLS, 2SLS, 3SLS, LIML) were applied to a two-equation model and investigated on their performances when plagued with the problem of misspecification error. A Monte Carlo method simulation method was employed to investigate the effect of these estimators due to misspecification of the model. The findings revealed that the estimates obtained by 2SLS and 3SLS are similar and variances by all the estimates reduced consistently as the sample size increases. The study had revealed that 2 3 SLS performed best using average of parameter criterion while OLS generated the least variances. LIML is mostly affected by misspecification. Keywords: Monte Carlo, Misspecification error, Simultaneous equation
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