COMPARATIVE ANALYSIS OF THE COMPRESSIVE STRENGTH OF HOLLOW SANDCRETE BLOCKS WITH DIFFERENT CAVITIES ARRANGEMENT

Previous analysis showed that cavity size and number on one hand and combinations thickness affect the compressive strength of hollow sandcrete blocks. Series arrangement of the cavities is common but parallel arrangement has been recommended. This research performed a comparative analysis of the compressive strength of cavities of different configurations. The test thin plate distributes the load on the block and the hollow block is regarded as a two way slab. The results showed that at equal end-web to centre -web thickness (1:2) and total cavity volume the stresses in the parallel configuration were higher than those in series configuration. The minimum stresses in the series arrangement were lower than the corresponding values in the parallel arrangement. In addition, the maximum stresses in the series arrangement were lower than the corresponding values for parallel arrangement. The implication is that at same volume and number of cavities and web thickness, the series arrangement results induced least stress. http://dx.doi.org/10.4314/njt.v35i2.

Comparison of Performance of Public and Private Boreholes

In the last fifteen years, a remarkable increase in the number of privately owned. There has been an increase in the individually owned and operated boreholes within the state because it is claimed that government owned boreholes breakdown too often. Hence, this study is aimed at comparison of the performance of three categories of boreholes namely: public operated boreholes owned by the Government, individual owned boreholes operated for commercial purpose, and private owned boreholes for private use in Rivers State. The comparison is in terms of functionality, operation and maintenance cost, and profit generated. Based on questionnaire completed by the management staff of several water providers and agencies 270 boreholes exist in the study area. Analysis indicate that 58(64.44%) of the total boreholes owned and operated by the government are not functional. The corresponding figures for the boreholes owned by individuals but operated for commercial use and the private owned and operated boreholes are 35(38.39%) and 20(22.22%) respectively. This is attributed to unplanned maintenance programme, poor feasibility studies, and lack of well-co-ordinated comprehensive well development structure. In terms of profit generation and low downtime, results show that the boreholes owned by individuals but operated for commercial purpose are the best while the worst are the private owned boreholes operated for private use. On the other hand, the least cost was obtained for the later

ASSESSMENT OF TRAFFIC FLOW ON ENUGU HIGHWAYS USING SPEED DENSITY REGRESSION COEFFICIENT

In an attempt to estimate the operating speeds and volume of traffic on highway lanes as a function of predicted demands, speed-density models were estimated using data from highway sites. Speed, flow and volume are the most important elements of the traffic flow. In this study, the speed-density regression models are compared using five highways in relation to their correlation coefficient based on the daily traffic flow data obtained from the roads. The traffic flow data were collected by hourly traffic count on each road. The coefficient of correlation (R) proved to have the best fit with a higher confidence and less variation for a two-lane highway than a one-lane highway. The space-mean speed (u) and density (k) relationship for the two-lane highways are; u,  and u whereas the space-mean speed (u) and density (k) relationship for the one-lane highways are; u =  respectively. This research provides practical application for speed estimation, construction, maintenance and optimization of the highways using the speed-density models which will enhance traffic monitoring, traffic control management, traffic forecasting and model calibration. http://dx.doi.org/10.4314/njt.v36i3.1

Review of Trenchless Technologies’ Successes and their Dependence on Precise Geotechnical Investigation

Geotechnical investigators are among the first to assess the physical setting of a project. Geotechnical investigations are performed to ascertain the character and variability of the strata underlying the site of the proposed structure and to assess those properties, which may affect the performance of the structure and the choice of method of construction. Deficient geotechnical investigations, faulty interpretation of results, or failure to portray results in a clearly understandable manner may contribute to inappropriate designs; delays in construction schedules, costly construction modifications, and use of substandard borrow material, environmental damage to the site, post construction remedial work, and even failure of a structure and subsequent litigation. Trenchless technology can be defined as the use of construction methods to install and repair underground infrastructure without digging a trench or open cutting. Trenchless projects should never been seen as a simple process but should always be seen as “site specific”. Geotechnical is one area in which certain characteristics can change rapidly. Knowing the sub-ground structure that the proposed borehole is to be constructed in, can significantly alter the parameters, design and type of construction method, site location, methodology, costs and expected construction time frame needed to complete the project successfully

Structural and Economic Viability of 2D/3D Finite Element Analysis of Conical Arched Roof Truss

Arch and conical roof trusses are employed when dealing with large span roof trusses. But a combination of the two geometrical shapes may lead to a better economical sections and a means of dealing with larger spans of roof truss that are not suitable for an arch or conical roof truss. Consequently, this paper examines the structural and economic viability of arched conical roof truss system based on 2D/3D finite element method analysis. Analysis of the results showed that truss members were subjected to higher axial forces in 2D analysis than 3D analysis, which will result to overdesign of the structural members and the attendant high construction cost. There are some variations observed in the axial forces for trusses located at edges of polygon when compared with the trusses located mid-point between two polygonal edges. This observation is quite significant in the sizes of the steel section properties of the members as well as in the fabrication and installation cost

Fungal Pre-mRNA 3′-End Processing

3' end processing of messenger RNAs (mRNAs) is not only an essential step in eukaryotic gene expression, but it also impacts many other aspects of mRNA maturation and decay. A large portion of eukaryotic genes produce multiple mRNAs with different 3' ends through alternative cleavage/polyadenylation (APA). mRNA 3' processing and especially APA has been increasingly recognized as an important mechanism for gene regulation. Much of what we currently know about eukaryotic mRNA 3' processing came from studies using the genetically tractable yeast systems. Here we review the fungal mRNA 3' processing system by describing both the evolutionarily conserved mechanisms as well as the fungus-specific features