Rivers State University of Science and Technology

About: Rivers State University of Science and Technology is a education organization based out in Port Harcourt, Rivers, Nigeria. It is known for research contribution in the topics: Population & Threatened species. The organization has 1826 authors who have published 1833 publications receiving 15183 citations.

Effect Of Drill String Rotation On The Dynamic Response Of Drilling Risers

Abstract: Abstract The effect of the rotation of a drill string on the response of a drilling riser has been studied. A governing equation for the flexural response that incorporates the effect of the drill string rotation is developed from first principles, and the resulting differential equation is found to have a variable coefficient, which is a function of the drill string rotational speed. Results simulated for the free vibration response show that the drill string rotation reduces the natural frequency and increases the amplitude of vibration of the drilling riser. The implication of these findings is that neglecting the effect of rotation of the drill string leads to under-estimation of the deflection and over-estimation of the natural frequency. Further analysis reveals that for a drilling riser of given dimensions, a drill string rotational speed exists at which the natural frequency of the drilling riser is theoretical equal to zero, and this rotational speed is the threshold rotational speed.

Damage Caused to Maize and Groundnuts by the Moths Plodia interpunctella (Hubn.) and Ephestia Cautella (Wlk.) and Control using Local Plant Materials

Abstract: In a comparative situation, the moths Plodia interpunctella (Hubn.) and Ephestia eautella (Wlk.) caused more damage in groundnuts (41.85% for P. interpunctelta; 29.21% for E. cautella) than in maize, when these commodities were stored for 1 month in plastic jars. For maize stored for 3 months in plastic and traditional storage gourds, the weight losses caused by the moths were: P. interpunctella—15.48% in jars; 4.53% in gourds; E. cautella—20.68% in jars; 4.12% in gourds. Orange peel suppressed two-thirds of the populations of P. interpunctella and E. cautella at a dosage of 20.0 g/100 g maize. Neem leaves caused 100% mortality of P. interpunctella at 15.0 g/100 g groundnut and suppressed more than half the population of E. cautella at 5 g/100 g groundnut. The results show that the plant materials utilised have some insecticidal properties against P. interpunctella and E. cautella over a short period.

Aspects of the population and reproductive ecology of sympatric hinge‐back tortoises (Kinixys homeana and K. erosa) in southern Nigeria, on the basis of specimens traded in bush‐meat markets

Abstract: The ecology and population structure of hinge‐back tortoises (genus Kinixys) was studied in the Niger Delta region of southern Nigeria (West Africa), where these species are actively hunted by local people for subsistence. The work is based not only on capture, mark and recapture study of free‐ranging specimens, but also on dissection of specimens offered for food, already dead, in the bush‐meat markets of the study region. The frequency of observation of the two most common species, i.e. K. homeana and K. erosa, was significantly higher in three areas subjected to ‘tradition conservation’ (because tortoises are worshipped by natives due to animistic taboos) than in three other areas where they are harvested. In particular, the juvenile class was much depleted in the three harvest areas. Analyses of market specimens demonstrated that, in both K. homeana and K. erosa, most of the females with oviductal eggs are found during the peak of the dry season, and that there was a positive relationship bet...