The Behaviour of Vertical Bell Laboratories Layered Space-Time Algorithm Combined with Multiuser Detection Schemes in Wireless Communication System

This paper provides the performance analysis of multiuser Vertical Bell Laboratories Layered Space-Time (V-BLAST) system receiver structures for Multiple-input Multiple-Output (MIMO) channel at a base station with assumption of perfect channel estimation and perfect timing delay estimation. In MIMO channels the receivers such as decorrelator, Minimum Mean Square Error (MMSE) and Multistage Parallel Interference Cancellation (MPIC) receiver outperform the conventional receiver. Withal, since the multiple antenna interference led to a strong impact on the performance degradation of a multistage interference cancellation receiver, the performance of MPIC receiver was highly degraded based on system loading

Geological Characterization of Azara Barite Mineralization, Middle Benue Trough Nigeria

The Azara Barites Mineralization in The Middle Benue Trough Occurs as Vein Infilling Materials associated with Lead-Zinc Lodes. A Fracture Formed as Single Linear Structures with thickness of  generally not more than 0.5m. The Geological Characterization of The Azara Barite Deposits which Include; Geotechnical, Petrological And Geochemistry Were Studied Within The Four (4) Selected  Veins Samples: V1 N (08020’40.6’’) E (0090 17’21.3’’) V 12 N(08021’59.0’’) E(009021’13.6’’) V13 N(08021’44.0’’) E (009021’14.6’’) V17 N(08022’27.1’’) E(0090 17’31.7’’). Soluble Alkaline Earth Metal Test (100mg/L) Indicate Presence of Calcium or  Magnesium which is Good for  Drilling Fluid, Hardness Capacity of  the Veins Mineralization ranges From 3.0 to 3.5 with an average Specific Gravity of 4.2. this classify the Veins as a High Grade Barite. Fluid Performance was Measured based on Yield Point and Plastic Viscosity which is high even at aging and at high Temperature. Quantitative Mineralogical Analysis reveals Barite as the Main Mineral with an  average  of 92 Wt.%   and Quartz as an associated Minerals with average  of  8wt.%.The Mineralogy revealed a Mineralization with One of the purest Veins and less  Number of Impurity, the Colour Index  Criteria also classify the Veins to be Melanocratic (60-90).The Elemental Composition of the Veins show  classes of Major Elements with average weight Percentage of greater than 1% (Sio2, SO3, Bao , Sro,) also  reveal  the Veins Are Oversaturated Based on The Composition of Sio2 And Metaluminous Group ( K2O+Na2O+Ca2>Al2O3>Na2O+K2O) With Modal Minerals Of Feldspar and Normative Minerals of Anorthite + Diopside. These have contributed to the grade and value of Azara Barite Mineralization Veins  and its Purity and Quality for Exploration Purposes. Keywords: Barite, Mineralization, Quartz,Benue Trough,Petrology,Veins,Azar

Assessment of Concrete Durability in Buildings: the Effects of the Quality of Cements Available in Lagos, Nigeria

This paper presents an investigative research that aims to find the effects of the cements available in Lagos, Nigeria on the durability of concrete within the study area. This is in an attempt to stem the rate of building failures in Lagos, Nigeria. The physical, the mechanical and the microstructural properties of the cements have been determined and compared with the standard properties as specified in relevant standards. 150mm cubes have been cast with these cements and all the sources of aggregates within the study area. Laboratory findings have discovered that all the cements investigated have fallen short of the expected strengths specified in standards but the labelled brands had values close to the strength standards but the unlabeled ones have fallen far short of the standard strength. The chemical analysis has complied with standard requirements except for their loss on ignition (LOI) values and the chemical properties have been complemented by the microstructural morphology as determined with the Scanning Electron Microscope (SEM) though the unlabeled brands have tendencies for alkali silica reactivity due to higher levels of alkali present in them. In assessing their performance in concrete, the concrete cube strength has met the expected 20MPa except for the unlabeled brands that have fallen a little short of it. The effects of these cements have been discovered to be very significant on the concrete durability within the study area. It is thereby recommended that the Nigerian regulatory agencies on cements make more efforts in order to ensure that cement manufacturers in Nigeria improve the quality of their cement brands in order to standard strength specification. All cements should be temporarily used as a 32.5 strength class, despising the labelled 42.5, pending when the manufacturers would fully comply their products to standard. Copyright © 2019 Praise Worthy Prize S.r.l. - All rights reserved

ASSESSMENT OF THE UTILIZATION OF DIFFERENT STRENGTH CLASSES OF CEMENT IN BUILDING CONSTRUCTIONS IN LAGOS, NIGERIA

Building collapse in Nigeria is so rampant now to the extent that it’s gradually not becoming a news when one occurs. Several factors being attributed as the cause of building collapses are based on opinions and in some cases based on investigative reports of selected buildings collapse. These factors are speculative since some intrinsic properties of debris materials tested during the investigation of selected collapse might be lost due to the impact of the collapse as a result of falling from great height and other debris falling on the tested material that these properties were intact before the collapse. Also, since the major causes of collapse in Nigeria is mostly attributed to poor construction process and the use of substandard material, this study assesses the quality of cements used in some selected sites and freshly produced cement from factory to compare with relevant standards, it also assesses the level of knowledge of the Nigerian construction professional using these cements to measure its applications. It was found out that the cements used in these selected sites were not all to standard even though all the freshly purchased cements met the required standard, this indicates that other factors might be responsible for the drop in standard properties. It was also observed that many of the professionals still need more training on the application of the different cement classes in structural concrete work

The Impacts of Public Libraries in Promoting Knowledge Society among Civil Servants in Nigeria

Public libraries serve as gateways to knowledge and culture by playing a fundamental role in society. The aim of this study is to examine the impacts of public libraries on the promotion of knowledge societies among civil servants in Oyo State, Nigeria. The total population was 570, and the sample size was 235 using a simple random sampling technique. The research design adopted was a descriptive survey. A questionnaire was used as an instrument for data collection, and a descriptive data analysis technique of frequency and the simple percentage was used. Findings revealed, firstly, that public libraries promote knowledge societies among civil servants through their collections, resources, and internet facilities to enhance the civil service culture. Secondly, public libraries have contributed significantly to improving and promoting knowledge societies as the civil servants make judicious use of the library facility to promote knowledge societies. Thirdly, public libraries have limitation that hindered the promotion of knowledge societies among civil servants; which are inadequate library materials, poor reading culture, inaccessibility to information resources, poor dissemination of information, and inadequate professional staff have. The recommendations of this study are the public libraries should provide more collections, adequate information resources tailored toward the promotion of knowledge societies, recruit professional staff and conduct regular training to improve their discharge of duties to meet the information needs of civil servants for the promotion of knowledge societies

Investigating for Pozzolanic Activity in Palm Kernel Nut Waste Ash (PKNWA) with Cement towards a Sustainable Construction

The earth is not inherited from our ancestors but borrowed from our children and should be returned the way we met it and even better. This is the essence of sustainability, preserving the earth. One of the main consequence of a non-sustainable world is global warming caused by the release of greenhouse gasses into the atmosphere that deplete the earth’s protective layer from extreme sun radiation. This results in global temperature rise leading to tsunamis and other “natural disasters” making us more vulnerable to extreme weather elements. Urbanization and industrialization bring about high construction rate to accommodate them resulting to global demand for concrete production. Concrete production contributes about 5% of the world’s carbon dioxide (CO2) emission and bulk of these emissions are in cement production. Cement is not an eco-friendly material and the sharp decrease in its use is highly needed to improve sustainable construction. Another issue discouraging its use is the rising cost, making housing unaffordable even to the middle class. This have resulted in finding series of housing financing systems to cope with rising cost of housing. One of the ways of achieving this is by the use of pozzolanic and blended cements to reduce the quantity of cements needed to meet the global concrete demand. This study examines the Pozzolanic Potentials of Palm Kernel Nut Waste Ash (PKNWA) as a blend with cement in Nigeria. Nigeria is currently the third world leading producer of palm which bears the nut and also accounts for over half of the palm produced in Africa. Palm kernel nut becomes an agro-waste when the oil is extracted. This study shows that PKNWA can comfortably replace cement by 10% and even produce a more durable binder than when cement is wholly used. The utilization of PKNWA in blended cement production will reduce the need for cement and prevent the ecological hazard resulting from the disposal of the waste palm nuts

A Comparative Analysis of Batching by Weight and Volume towards Improved Concrete Production

Batching of concrete is generally the proportioning of the different constituents of concrete before mixing which could be by weight or volume. Mix-design justified by trial test is the best method to achieve a concrete of desired properties. Standardized prescribed concrete (SPC) mix-design is mostly adopted in mass concreting to high strength concreting applications in most developing nations. British standards accept volume batching for SPC only in mass concrete (<15 MPa) but batching by weight for normal and higher strength concrete. Structural concrete like in storey buildings requires at least a normal strength concrete (>20 MPa) recommended to be batched by weight. Designs batched by volume have been identified as the most commonly used method in concrete production in Nigeria and most developing nations, especially by medium to small scale construction firms due to the very high cost of employing batching plants. This research work developed a modified volumetric batch mix-design that will be equivalent to SPC design mix batched by weight in normal and higher strength concrete. The physical properties of the constituent concrete materials, fine aggregate, 12 and 19 mm sized coarse aggregates were determined. The strength of SPC mix of ST2, ST4, and ST5 to British standard were determined when batched by weight and their volume equivalents mix-design batch determined. The strengths of these SPC mixes were batched by volume and their weight equivalent batch-design determined. A relationship was determined between both batching mixdesign methods for all the prescribed mixes and strengths using the binder-aggregate and coarsefine aggregate ratios, such that the preferred weight batching design mix could be achieved by a modified mix-design batched by volume. This study concludes that concrete mix-design batched by weight is superior to when batched by volume and the desired design batching by weight could be achieved by generating a modified mix-design-batch by volume. This will improve the quality of concrete storey buildings in most developing nations

Path planning in nuclear facility decommissioning: Research status, challenges, and opportunities

Research data for this article: Data not available / No data was used for the research described in the article.Supplementary data are available online at: https://www.sciencedirect.com/science/article/pii/S1738573321003144#appsec1 .During nuclear facility decommissioning, workers are continuously exposed to high-level radiation. Hence, adequate path planning is critical to protect workers from unnecessary radiation exposure. This work discusses recent development in radioactive path planning and the algorithms recommended for the task. Specifically, we review the conventional methods for nuclear decommissioning path planning, analyze the techniques utilized in developing algorithms, and enumerate the decision factors that should be considered to optimize path planning algorithms. As a major contribution, we present the quantitative performance comparison of different algorithms utilized in solving path planning problems in nuclear decommissioning and highlight their merits and drawbacks. Also, we discuss techniques and critical consideration necessary for efficient application of robots and robotic path planning algorithms in nuclear facility decommissioning. Moreover, we analyze the influence of obstacles and the environmental/radioactive source dynamics on algorithms' efficiency. Finally, we recommend future research focus and highlight critical improvements required for the existing approaches towards a safer and cost-effective nuclear-decommissioning project.This research work was funded by Harbin Engineering University. We also acknowledge the technical support project for Suzhou Nuclear Power Research Institute (SNPI) (NO.029-GN-B2018-C45-P.0.99–00003), the Foundation of Science and Technology on Reactor System Design Technology Laboratory (HT-KFKT-14-2017003) and the project of Research Institute of Nuclear Power Operation (No.RIN180149-SCCG)

Pulverized Calcined Clay and Carbide Waste as Alternative Binder in Concrete and Mortar Applications for Sustainable Construction

Portland cement (PC) based concrete is the world’s most consumed man-made material and this consequently puts lots of demand on cement as a binder. The CO2 gas emission during cement clinker production has placed this important material into non-environmental-friendly classification with quest for greener alternatives being on the rise. A recent study showed combination of Pulverized Calcined Clay (PCC) and Calcium Carbide Waste (CCW) as possible alternative for total PC replacement with resulting appreciable mortar strength but delayed setting times and lower strength than PC mortars. This paper reports on effects of PCC-CCW as alternative binder on strength properties of mortars. The mortar mixes had superplasticizers added to reduce water/binder ratio while the CCW was treated to reduce impurities with a view to improving the strength development and a bid to mitigate the observed setbacks of earlier study. The pozzolanic activity indices of the PCC was determined via X-Ray Fluorescence(XRF) and strength determination (strength activity index). The PCC was combined with Purified CCW to determine the binder’s strengths at varying PCC:CCW replacements to determine the prescribed mix combination for optimum strength. Improved optimised mortar strength of 13.11MPa was achieved compared to 11.89MPa in the previous stud

Factors Affecting the Competencies and Project Delivery of Small-Sized Indigenous Construction Firms in Lagos State

Every industry is prone to problems Performance is a general challenge affecting construction and most especially small-sized indigenous construction companies. The study focused on determining the likely factors affecting the competencies and project delivery of small-sized construction firms in Lagos. 60 questionnaires were designed and administered to professionals (15-Architects, 15-Builders, 15-Engineers, and 15-Quantity Surveyors) working in the construction companies in Lagos State and 48 questionnaires were retrieved. These questionnaires were analysed with SPSS and several findings were derived from this analysis. The various factors affecting the performance and project delivery at varying degrees are: high cost of plants, equipment, materials and labour, lack of skilled craftsmen, unavailability of funds, poor managerial skills, lack of government patronage, and poor communication among stakeholders. The study found out that the most prominent factors are poor managerial skills, lack of project planning and unavailability of funds. The main factors affecting the performance of small sized indigenous construction firms are based on three key elements namely time, quality and cost. These three elements when properly harnessed will increase the performance of small sized indigenous firms. The study recommended that the use of ICT would help improve performance by making work flow more easily. Access to bank loans and more machinery on site and sufficient government patronage would improve performance. It concluded that better management and project planning would go a long way in improving competencies and project delivery of small sized construction firms