Evaluating the Strength Characteristics of Clay- Gravel Mixtures

Shear strength is one of the most important soil properties in almost all geotechnical engineering problems. Therefore, this study was aimed at investigating the effect of gravel on the shear strength of clayey soil. Two clayey soil samples were obtained from a dug pit from different locations in Osogbo, Osun State and the gravels were collected locally. Three different gradations of gravel (2-6mm, 6-12mm, and 12-20 mm) were mixed in a dry state in percentages of 5, 10, 15, 20, 30, 40 and 50% with the collected clay soil respectively. Initially, some physical properties of clayey soil and the gravel, which include specific gravity, particle size analysis, liquid limit and plastic limit, were determined in accordance with BS 1377-3:2018. Consequently, the California Bearing Ratio (CBR) and Consolidated - Undrained (CU) triaxial compression tests at three different confining pressures of 50, 100 and 150 kN/m2, with a loading rate of 0.5 mm/min were carried out on the clay-gravel mixtures in accordance with BS 1377 (1990). The results from the CBR test indicated that the CBR value of the clay-gravel mixtures was higher than that of pure clay. The result of shear strength showed that the cohesion and effective angle of internal friction increases as the concentration of gravel increases from 0 to 50%. As the gravel size was increased from 6-12mm, effective cohesion reduces and angle of internal friction increases.  It concluded that locally available gravel can be used to improve the strength properties of clayey soil for engineering construction

Soils Parameters and Constitutive Relations Under Multiaxial Cyclic Loading

A generalized constitutive model based on the theory of plasticity is proposed and utilized to characterize stress-deformation behavior of soils and geological materials under complex and cyclic multiaxial loadings. It allows for factors such as hardenings, volume changes, stress paths, cohesive and tensile strengths and variation of yield behavior with mean pressure. It is applied to characterize behavior of soils, concrete and rocks. The Constants for the model are determined from series of available laboratory tests conducted under different initial confinements, cyclic hydrostatic preloading and stress paths obtained by using multiaxial and cylindrical triaxial testing devices. The model is verified with respect to observed laboratory responses. Overall, the proposed model is found suitable to characterize the behavior of geological materials such as soils, concrete and rocks and involves less or equal number of constants compared to available models of similar capabilities and is easier to implement in numerical solution procedures

An augmented moment method for stochastic ensembles with delayed couplings: I. Langevin model

By employing a semi-analytical dynamical mean-field approximation theory previously proposed by the author [H. Hasegawa, Phys. Rev. E {\bf 67}, 041903 (2003)], we have developed an augmented moment method (AMM) in order to discuss dynamics of an $N$-unit ensemble described by linear and nonlinear Langevin equations with delays. In AMM, original $N$-dimensional {\it stochastic} delay differential equations (SDDEs) are transformed to infinite-dimensional {\it deterministic} DEs for means and correlations of local as well as global variables. Infinite-order DEs arising from the non-Markovian property of SDDE, are terminated at the finite level $m$ in the level-$m$ AMM (AMM$m$), which yields $(3+m)$-dimensional deterministic DEs. Model calculations have been made for linear and nonlinear Langevin models. The stationary solution of AMM for the linear Langevin model with N=1 is nicely compared to the exact result. The synchronization induced by an applied single spike is shown to be enhanced in the nonlinear Langevin ensemble with model parameters locating at the transition between oscillating and non-oscillating states. Results calculated by AMM6 are in good agreement with those obtained by direct simulations.Comment: 18 pages, 3 figures, changed the title with re-arranged figures, accepted in Phys. Rev. E with some change

Unmet social needs and teenage pregnancy in Ogbomosho, South-western Nigeria

Background: Consistent high teenage pregnancy rates in South-western Nigeria are characteristically underpinned by the unmet social needs of the teenagers.Objective: To elicit intergenerational views on the influence of unmet social needs on teenage pregnancy. Methods: Through a descriptive and cross-sectional design, a total of 174 respondents who were either pregnant teenagers, teenage mothers during the survey or had been pregnant as teenagers, were interviewed, using questionnaire supplemented with 12 key informant interviews.Results: With the mean age of 16.5 years, and educational status range of between primary and below (25.8%) and tertiary (9.8%) levels, only 39.7% respondents were married, about half (47.7%) remained single while others were separated (12.6%). Less than half (44.9%) of the respondents were engaged in occupational activities. The unmet material and financial supports expected from parents (43.1%), the lack of free education from government up till secondary school level (51.2%), the lack of sex education and knowledge needs for signs of maturity (53.4%) and discouragement from friends not to have boyfriend (66.1%) prone teenagers to unplanned pregnancy.Conclusion: Promotion of sexual education and parental care is encouraged as strategy against unplanned pregnancy among teenagers.Keywords: Unmet needs, pregnancy resolution, teenagers, Nigeri

Preparation of Waste Paper Fibrous Cement and Studying of Some Physical Properties

Waste paper is available in environment from different sources, such as office, newspaper and markets. Waste papers are the abundant source of cellulose and may be used as landfill. Using of these wastes in building materials has two benefits, the first one has reduced the environmental pollution and the second improves the physical properties of concrete and building bricks (or blocks). Addition of waste paper cellulose to concrete at certain percentage improve its thermal insulation properties and affect its density to produce lightweight and insulating building materials. The material which produces by using waste paper is called papercrete. It is a mixture of waste paper pulp, sand, cement and water by replacing the cement by waste paper pulp at a certain percentage. Also fibrous cement could be produced by mixing of waste paper pulp with cement and water. In the current work the waste paper was processed to obtain the raw materials of papercrete and fibrous cement. The processing method includes a sequence of processes which are shredding, soaking, mixing, dewatering and drying. In the dewatering process, a wet pulp was obtained and it can be used as it is in the mixtures of papercrete or fibrous cement. A dry pulp also could be used. It is observed that one kilogram of office paper and that of newspaper produces 3.24 kg and 3.26 kg of wet paper pulp respectively. The dry pulp, which is produced during the drying process is 0.954 kg and 0.949 kg for 1 kg of office paper and newspaper respectively. Design of mix proportion, test of water absorption, apparent porosity and drying curve of samples with different percentage of paper pulp were investigated in the present work. Keywords: wastepaper, papercrete, fibrous cement, porosity, water absorption, bulk densit

Application of intelligent technique for development of Colpitts oscillator

In this paper, new method of Colpitts oscillator designing through combination of Genetic Algorithm and Artificial Neural Network (ANN) has been suggested. The Thevenin's resistors for the common base Colpitts oscillator are optimized through application of GA and ANN. The developed common base Colpitts oscillator has shortest transient time response and stable Direct Current (DC) stability in the long term operation. Involvement of GA and ANN successfully optimize between transient time response and steady state response of common base oscillator. Application of these two artificial intelligent techniques assist faster selection of optimizes components values such as resistance values during circuit development rather than conventional method which used intuition techniques to develop the circuit

Fuzzy antiwindup schemes for NCTF control of Point-Topoint (PTP) positioning systems

The positioning systems generally need a controller to achieve high accuracy, fast response and robustness. In addition, ease of controller design and simplicity of controller structure are very important for practical application. For satisfying these requirements, NCTF (nominal characteristic trajectory following) controller has been proposed as a practical PTP positioning control. However, the effect of actuator saturation can not be completely compensated due to integrator windup because of plant parameter variations. This study presents a method to improve the NCTF controller for overcoming the problem of integrator windup by adopting fuzzy anti-windup schemes. Two fuzzy antiwindup schemes based on Mamdani and Takagi-Sugeno fuzzy system are developed and evaluated their effectiveness. The improved NCTF controller with the proposed fuzzy anti-windup schemes is evaluated through simulation using dynamic model of a rotary positioning system. The results show that the improved NCTF controller with Takagi-Sugeno-based fuzzy windup is the best scheme to compensate for the effect of integrator windup

Drug Permeation across the Blood-Brain Barrier: Applications of Nanotechnology

The blood-brain barrier (BBB) is a neurobiological frontier that isolates brain tissues from the blood vascular system. Its main role is to protect the brain and the central nervous system from external fluctuations in hormones, nutrients and drugs, while allowing the passage of water and small lipophilic molecules. Diffusion across the BBB can occur through several biological mechanisms, but the most common one is simple diffusion, which mainly depends on the size, lipid solubility and concentration gradient of the molecule. Because of the highly dense network of capillary endothelium cells found in the BBB, most of the drugs are not able to cross this physiological barrier. Delivering therapeutic agents to the brain is thus a big challenge, which may prevent treatment of important neurological diseases. In order to overcome this difficulty, researchers have used nanotechnology to help the passage of drugs across the BBB. Nanotechnology has significantly contributed to the field of biotechnology by improving the strategies for drug delivery, and by providing novel carriers for safe and effective brain targeting. The aim of this review is to discuss in more details the anatomical structure and the functions of the BBB, as well as its significance in neurological diseases. A closer look will be given at the transport mechanisms across the BBB. This review finally explores the most recent advances in the field of nanotechnology for drug delivery in the brain, and gives meaningful examples of delivery systems developed including the micelles, liposomes, dendrimers, microcapsules and polymeric nanoparticles

Principal Component Analysis Technique for Finding the Best Applicant for a Job

This paper focuses on the use of principal component analysis technique (PCA) in choosing the best applicant for a job in Cihan University-Erbil. Cihan University has a panel of judges (University staff) to help in choosing the applicants for a job by evaluating or rating each one on different scale of preference and different type of characteristics. This process usually creates complicated multivariate data structure, which consists of 25 applicants for a job rated by a panel of judges on 17 characteristics [25 rows, applicants, and 17 columns, characteristics]. PCA plays a crucial role in conducting impactful research as it offers a potent technique for analyzing multivariate data. Researchers can utilize this method to extract valuable information that aids decision-makers in problem-solving. To ensure the appropriateness of data for PCA, certain testing procedures are necessary. In this study, two tests, namely the Kaiser-Meyer-Olkin (KMO) Measure of Sampling Adequacy and Bartlett's Test of Sphericity, were performed, and their significance is vital. The findings indicate that the data employed in this research are suitable for PCA. Scoring and ranking procedures as extra tools were used to see that applicant No. (1) is the first accepted for a job, applicant No. (17) is the second, applicant No. (12) is the third, and so on