The Development of Practice in Permeation Grouting by using Fine-grained Cement Suspensions

Grouting includes a range of processes that involve the injection of wet or dry materials into the ground to provide improved engineering properties. Common aims are to increase strength or stiffness or to reduce permeability within the mass of ground treated. This paper, mainly, addresses permeation grouting for the improvement of soils, in terms of strengthening or reduction of permeability, and compensation grouting for the displacement of structures during subsurface exploration. The grouts used to make permeation grouting are suspensions and chemical solutions. The suspensions penetrate well into soils with granulometry up to coarse sand. On the contrary, the chemical solutions penetrate satisfactorily in finer formations up to fine sands or coarse sludges. Because some chemical solutions are toxic or generally harmful to the environment and humans, an effort has been made internationally in recent years to replace them with inorganic fine-grained suspensions.

Survey on Mitigating the Problems of Parabolic Reflectors for Efficient Communication

In this paper, various problems associated with parabolic reflectors, its causes and the approach to mitigate these problems are discussed. The problems include; side lobe radiations, edge diffraction, aperture blockage, cross polarisation, feed spill over, feed illumination taper, pointing error, surface error and phase error. These problems have adverse effect on the overall gain, efficiency and directivity of the antenna thereby inhibiting efficient communication process. The result of the survey reveals that, phase error tends to be the most difficult of the aforementioned problems due to the challenges associated with locating the phase centre at reflector’s focus. The aperture blockage seems to have the least method of solution, because the problem can be solved by changing the centre feed to an offset feed. Detailed investigation of these problems and the relevant solutions are necessary, since parabolic reflectors are among the most common antennas with diverse application.

Is ICT a Prospect for Young Professionals to Mature Business Within SME`s in East Africa Community?

Nowadays, young individuals in the East African community are using information and communication technologies in different ways, some as an opportunity to make a conversation with relatives and others take it as a distraction. Information and communication technology is an opportunity for young individuals to grow businesses. Young professionals need to investigate in small and medium-sized enterprises and should not only expect to get jobs elsewhere. The issue is that young professionals in the East African community cannot compete with each other when their mindset on doing business through small and medium-sized enterprises are taken differently and the levels of economic of these countries are very different. This article is motivated by the researcher’s observation analysis about young professionals in the East Africa community who know information and communication technologies, and unfortunately, they use them in a way that cannot make small and medium-sized enterprises successful. The main goal of this study is to describe information and communication technologies as an opportunity to buy or sell goods or services through small and medium-sized enterprises. This study will provide a better understanding to the lecturer, especially young professionals to take information and communication technologies positively as an opportunity to grow business through small and medium-sized enterprises and to know the strategy to use to sell products and how to manage consumer’s behavior through their needs. Young professionals need to build business skills and linkages with local and international businesses by exchanging business ideas and information via information and communication technologies.

AN OVERVIEW OF THE COMPOSITE DESIGN OF SMART GRID DUE TO POWER DEMAND,PRODUCTION AND POWER DEFICIT IN NIGERIA

The general aim and objectives of the research is to demonstrate an overview of the composite design and emphasis of the implementation of an effective and efficient smart grid power system that will address the challenges of epileptic power due to power demand, power production and power deficit in Nigeria.

Decommissioning Plans for Fixed Offshore Platforms: A Brief Revision

Brazil began to explore its seas in the 60’s of the XX Century looking for petroleum. This journey began in the Northeast and the first oil field produced offshore was the Guaricema Field, in the State of Sergipe. During the 70’s, Petrobrás found oil in the Campos Basin, between the States of Espírito Santo and Rio de Janeiro, that became the most important oil province in Brazil until the discovery of the Pre-Salt province, in the Santos Basin. As these fields are producing for a long time, many of them are already completely depleted or their production is in way of to be not commercial anymore, and their facilities need to be decommissioned. This review of decommissioning practices of fixed offshore platforms carried out worldwide has focus on the removal of topside with special vessels designed for this purpose or with conventional methods (crane vessels + barge). It will show the benefits of using specialised heavy lift vessels to remove the topsides and move it to shore for dismantling / recycling / reuse / disposal. The cases for study were the successful decommissioning projects in the North Sea: Brent B/D, Valhall QP, Viking, Curlew, Eider A, Golden Eye and Leman, Iwaki-Oki, Halfweg Q1, Yme and Ninian North.

A Combination between Synthetic Unit Hydrograph (SCS) and Rational Method in a similar Conditions Water Shed

Studying watershed characteristics and choosing the most applicable methods to determine the amount of access rainfall that ran off is very important in many engineering applications, especially hydrology applications. That is to know the more suitable methods for protection against floods and to maximize benefits from the excess water. This study aims to establish a relation between the rational method and the SCS method. A subbasin in Wadi Dahab in Sinai, Egypt is investigated as a study area. To achieve the study aims, HEC-WMS software is chosen, which can analyze a watershed by using DEM and delineating basin. It calculates also important watershed parameters like area, runoff distances, and slope. The rainfall data is compiled and arranged. A statical analysis is executed to obtain the IDF curves. Hyfran-plus software is employed to locate the maximum depths for different return periods. Various values for the time of concentration are studied. It is concluded that the difference between the rational and SCS methods is great for the time of concentration till 2 hours, then it decreases obviously from 2 till 6 hours. Also, it is concluded that the difference between the two methods is bigger for the small return periods of 2 and 5 years for all values of the time of concentration. Employing the obtained equations, the peak runoff for one of the two methods (the rational and SCS methods) can be calculated knowing the time of concentration and the peak runoff for the second method.

Solution of SIR Infection Equation Using Data Assimilation

The new coronavirus infection (COVID-19) is rampant. The most troublesome part of this infection is the time between infection and onset and the infectiveness for several days even in the not-onset state. Therefore, a considerable number of infected persons with infectivity are left unchecked. Therefore, even if the infection status is simulated by the SIR equation or the like, the true values of the infection parameters and the true number of infected persons cannot be grasped. However, it is possible to observe the infection status, and the daily number of infected people and the cumulative number of infected people are announced. These numbers are not true values, but they reflect true values. It is impossible to grasp the true value only by the SIR equation, but it will be possible to estimate the true value by combining it with the observation equation. In short, the data assimilation framework is considered to be effective. We report this effectiveness because we were able to confirm this effectiveness from the numerical results.

Applying Tabu Search Optimisation in Zone Distribution System Reconfiguration A Stochastic Model

The main idea in the distribution system is to reconfigure the network and to change the sectionalizing switches' state to reduce power loss and maintain system stability. In network reconfiguration, a key role is to find the appropriate network topology that does have the lowest losses during any conditions present within the network. Reliability, security, and system operating limitations are the most significant parts of the network reconfiguration that are suitable. In the work, the authors suggested to apply Tabu search optimisation technique to solve the problem of network reorganisation in the distribution system by creating a stochastic model of a virtual zone based on data prepared in a previous study by the first author. The stochastic model consists of four feeders and 106 buses. The validity of the suggested technique is verified by relying on standard practices and its ability to establish a correct network topology in the system distribution. This investigation determines that the suggested technique is excellently suitable for creating a virtual zone network and can be applied in reality.

Some Workout Problems on Motion of Raindrop

The motion of rain drop through atmosphere is an interesting classical problem because of the fact that air resistance and moisture accretion are integral part of it. Mathematical modeling of it using Newtonian formalism is considered here and discussions are made for no mass accretion and air resistance proportional to nth power of velocity. We use python program and library extensively to find the terminal velocity of rain drop. Graphs show close agreement and velocity power up to n=3 is good.

Stress-Strain Characteristics of a Cement-Bentonite Mix for a Barrier System The Implication of Time and Curing

For containment and water exclusion purposes, cement-bentonite (CB) barrier walls are usually built, with certain design criteria specified for the wall to fulfill intended purposes. While permeability is believed to be the most important criterion, it can be impacted by the stress-strain properties of the wall, which define the strength and stiffness. This study investigates the influence of curing time, confinement, rate of axial deformation, and quantity of cement (mix of Portland cement (PC) and ground granulated blast furnace slag (GGBS)) on the stress-strain properties of CB slurry walls. An unconfined compressive test supported by (i.e. UCT) undrained triaxial (UUT) tests were carried out on specimens prepared from two mix-designs (differentiated by the proportion of GGBS in the cement component) and cured 7, 14, 28, 60, and 90 days. Two rates of deformation (1.0mm/min and 1.2mm/min) were examined, using a range of confining pressure (i.e., 50 - 200 kPa) in the UUT. The results reveal that varying rates of deformation and the range of confining pressures have no clear influence on the mechanical properties (e.g., deviator stress, shear strength, and stiffness) of the CB mix-designs. However, increased curing time, and the proportion of GGBS significantly improved these properties. An increased proportion of GGBS enhances early strength. Thus, further work needs to be done to establish a balance between adequate strength and adequate flexibility of CB walls in order to not compromise permeability.