Coded Index Modulation for Non-DC-Biased OFDM in Multiple LED Visible Light Communication

Use of multiple light emitting diodes (LED) is an attractive way to increase spectral efficiency in visible light communications (VLC). A non-DC-biased OFDM (NDC OFDM) scheme that uses two LEDs has been proposed in the literature recently. NDC OFDM has been shown to perform better than other OFDM schemes for VLC like DC-biased OFDM (DCO OFDM) and asymmetrically clipped OFDM (ACO OFDM) in multiple LEDs settings. In this paper, we propose an efficient multiple LED OFDM scheme for VLC which uses {\em coded index modulation}. The proposed scheme uses two transmitter blocks, each having a pair of LEDs. Within each block, NDC OFDM signaling is done. The selection of which block is activated in a signaling interval is decided by information bits (i.e., index bits). In order to improve the reliability of the index bits at the receiver (which is critical because of high channel correlation in multiple LEDs settings), we propose to use coding on the index bits alone. We call the proposed scheme as CI-NDC OFDM (coded index NDC OFDM) scheme. Simulation results show that, for the same spectral efficiency, CI-NDC OFDM that uses LDPC coding on the index bits performs better than NDC OFDM

Generalized Spatial Modulation in Indoor Wireless Visible Light Communication

In this paper, we investigate the performance of generalized spatial modulation (GSM) in indoor wireless visible light communication (VLC) systems. GSM uses $N_t$ light emitting diodes (LED), but activates only $N_a$ of them at a given time. Spatial modulation and spatial multiplexing are special cases of GSM with $N_{a}=1$ and $N_{a}=N_t$, respectively. We first derive an analytical upper bound on the bit error rate (BER) for maximum likelihood (ML) detection of GSM in VLC systems. Analysis and simulation results show that the derived upper bound is very tight at medium to high signal-to-noise ratios (SNR). The channel gains and channel correlations influence the GSM performance such that the best BER is achieved at an optimum LED spacing. Also, for a fixed transmission efficiency, the performance of GSM in VLC improves as the half-power semi-angle of the LEDs is decreased. We then compare the performance of GSM in VLC systems with those of other MIMO schemes such as spatial multiplexing (SMP), space shift keying (SSK), generalized space shift keying (GSSK), and spatial modulation (SM). Analysis and simulation results show that GSM in VLC outperforms the other considered MIMO schemes at moderate to high SNRs; for example, for 8 bits per channel use, GSM outperforms SMP and GSSK by about 21 dB, and SM by about 10 dB at $10^{-4}$ BER

Accreditation and Quality Assurance in Nigerian Universities

This paper examines the impact of accreditation on quality assurance in Nigerian universities. Descriptive survey design was used for the study. A sample of 74 universities out of 124 universities in Nigeria presently (22 federal owned and 22 state owned, and 30 private universities} was drawn using proportionate stratified random sampling technique. Also, simple random sampling was used to select 20 respondents (including teaching and non-teaching staff, who are in charge of the data needed for the study) were selected from each university, which amounted to 1480 staff. The study developed and used two sets of questionnaire tagged “Accreditation Procedures and Minimum Academic Standard Questionnaire (APMASQ), and Quality Assurance Questionnaire (QAQ)” with correlation coefficient (r) of 0.73 and 0.69 respectively and complimented with secondary data from NUC records. Pearson product moment correlation coefficient (r) was employed to analyse the data. While the null hypotheses developed for the study were tested at .05 level of significance. The findings revealed that there is significant relationship between accreditation and resource input into Nigerian universities, quality of output, quality of process, and no significant relationship between accreditation and quality of academic content. It is therefore recommended among others that human capacities should be built in the area of quality assurance so as to ensuring quality in Nigerian universities. Also, accreditation exercises and conducts should be properly manipulated and supervised without playing politics so as to achieve education standards, quality and effectiveness for purpose of accomplishing goals of university education in Nigeria. Key words: Quality assurance, Quality, University education,    Accreditation, Standards, Quality improvement

Integration of magnetic residuals,derivates and located euler deconvolution for structural and geologic mapping of parts of the precambrian gneisses of Ago-Iwoye, Southwestern Nigeria

Ground based magnetic survey conducted between longitude 06O 55I 51IIN –06O 55I 54IIN and latitude 03O 52I 06IIE –03O 52I 4.8IIE (Olabisi Onabanjo University) remarkably revealed a consistent subsurface NW -SE structural azimuth of localized discontinuities within the shallowly buried heterogeneous basement rocks, which at exposed locations are composed of strongly foliated granite gneiss and migmatite-gneiss with veins and veinlets principally orientated in NNW –SSE direction.Magnetic survey of the area was preceded by site inspection to avoid metallic objects interferences. Field procedure in the area involved Cartesian gridding, base station establishment, data acquisition at gridded points, and repeated bihourly diurnal checksat the base station. At the processing stage, diurnal variation effect was aptly removed before subjection to Kriging (gridding). The gridded data was then prepared as input for Forward Fourier Filter Transform (FFT), which upon definition and implementation enabled Butterworth filtering of isolated ringing effects, reduction to the equator (RTE) for geomagnetic correction, and the use of Gaussian and Upward Continuation filtering for regional magnetic intensity trend determination. Removal of the regional magnetic intensity (RMI) from the total magnetic intensity (TMI) resulted in the derivation of the residual anomaly. Enhancement filters adopted for better resolution of the residual magnetic gradient include analytical signal (AS), tilt-angle derivative (TDR), vertical derivative deconvolution (VDD), and the first vertical derivatives (FVD).TMI and RMI values range between 32925nT –33050nT and 32935nT –333050nT respectively, while the residual gradient ranges between 15nT/m and10nT/m; AS ranges between 0.28nT/m and4.1nT/m; and TDR ranges from-1.4nT/m to 1.4nT/m. Source depth calculation estimated from power spectrum analysis and Euler deconvolution ranges between 1m and15m. Composite overlay of magnetic maps revealed jointed and faulted zones within the area; exhibiting a NW-SE principal azimuth of Liberian orogenic impress, which are in consistence with the foliation direction of the jagged foliated bedrock with an estimated maximum overburden of about 15m.The structural significance of this area as a prospective hydro-geological centre, and as an undesirable spot for high-rise building has been accurately evaluated from research findings. Application of integrated geophysical approach, complemented by detailed geological studies may furnish greater information about the subsurface structural architecture.Keywords:Gneisses; Ground Magnetic Surveying;RTE;Structural discontinuities;TDR.1INTRODUCTIONStructuralmapping is an integral part of geologic surveys. It involves measurements, analyses, interpretation and recognition of geometrical features (structures) generated by rock deformations [1]. These structures often serve as fountains of environmental challenges or unparalleled opportunities depending on their modesof occurrences, which in most cases are imminently controlled by the dynamic interplay of differential stress distributions within the earth interior. In line with the principle of uniformitarianism, a broad understanding about Earth’s paleo processes and internal workingsare deductible from the various deformation types for diverse applications. Deductible inferences from brittle deformationsinclude the kinematics of crustal blocks, orientation of principal axes of regional and local stresses, and geometry. Deeper insights indeep seated stresses, regional movements and block motions are obtainable from ductile deformations

An Assessment of Water Quality of Borgaon Reservoir in Sangli District of Maharashtra, India

Abstract The study reveals on study on influence on environmental parameters on water quality at Borgaon reservoir in KavatheMahankal tahsi

Documentary Credit on International Trade Financing: Its Nature and the Legal Implications

A letter of credit (L/C)[1] is defined in Article 2 of Uniform Code of Customs and Practice (UCP) as . . . any arrangement, however named or described, whereby a bank (the ‘issuing bank) acting at the request and on the instructions of a customer (the ‘Applicant) or on its own behalf: i.              is to make payment or to the order of a third party (the ‘Beneficiary’), or is to accept and pay bills of exchange (Draft(s) drawn by the Beneficiary; or ii.             authorizes another bank to effect such payment, or accept and pay such bills of exchange (draft(s); or iii.            authorizes another bank to negotiate against stipulated document(s) provided that the terms and conditions of credit are complied with. It is an instrument issued by a bank on behalf of the importer (buyer) promising to pay the exporter (beneficiary) upon presentation of shipping documents in compliance with the terms stipulated herein. [1] Article 2 of Uniform Code of Customs and Practice (UCP) 1993 revisio

STUDIES ON GENITAL DISORDERS OF COWS SLAUGHTERED AT ZURU, KEBBI STATE, NIGERIA

In a survey carried out between April and December, 2003 to investigate the incidence of reproductive pathology among cows slaughtered at Zuru central abattoir and some selected slaughter slabs within Zuru emirate, Kebbi State, a total of 84(16.8%) abnormalities were recorded from 500 female genitalia examined. The incidence of various abnormalities observed included bilateral Ovarian follicular cysts (1.6%), Endometritis (0.4%), Uterine hypoplasia (1.0%), Pyometra(1.2%), Ovarian tumour (0.2%), Cystic endometrial hyperplasia (0.4%), Para ovarian cyst (0.2%), Vulvo-vaginitis (1.6%), Salpingitis (2.0%), Ovarian abscess (0.2%), Ovarian agenesis (2.0%) and vulva tick infestation (6.0%). From this study, tick infestation of the vulva ranked the highest genital pathological condition recorded and the ticks were identified as Boophilus spp. This was closely followed by Salpingitis and Ovarian agenesis. These conditions most times result into conception failures, abortions or still births, situations that often lead to the culling of the animals by their owners. It is suggested that timely medical interventions to diagnose and treat these genital disorders will however save some of these economic losses. This study provides information on the diseases affecting reproductive tracts as well as their adverse effects and significance in cattle production and breeding in Nigeria. It recommends a close watch on the cattle industry by relevant stake holders with a view to preventing unwarranted slaughter of viable cows erroneously believed to be unproductive. &nbsp

Reverse genetics in Candida albicans predicts ARF cycling is essential for drug resistance and virulence

Peer reviewedPublisher PD

Asymmetric Squares as Standing Waves in Rayleigh-Benard Convection

Possibility of asymmetric square convection is investigated numerically using a few mode Lorenz-like model for thermal convection in Boussinesq fluids confined between two stress free and conducting flat boundaries. For relatively large value of Rayleigh number, the stationary rolls become unstable and asymmetric squares appear as standing waves at the onset of secondary instability. Asymmetric squares, two dimensional rolls and again asymmetric squares with their corners shifted by half a wavelength form a stable limit cycle.Comment: 8 pages, 7 figure

HUMAN AND PHYSICAL CAPITAL OF CRAFTSMEN IN THE CONSTRUCTION INDUSTRY

Construction craftsmen are one of the most vulnerable groups of workers. Hazardous working environment, temporal nature of work and poor wages characterize construction work. The study assessed the livelihood pattern of craftsmen with a view to improving their socioeconomic conditions. The study adopted a descriptive case study research design. Human and physical capitals of craftsmen were assessed. The most common livelihood activity of the craftsmen surveyed was bricklaying. The livelihood outcome of the craftsmen can be described as fair since they were able to meet their basic needs; however, the craftsmen desire to have a more steady flow of income and a better neighbourhood to live in