The behaviour of remolded Batu Pahat soft clay with different OCR values under cyclic loading

The Batu Pahat Soft Clay, (BPSC) of Universiti Tun Hussein Onn Malaysia, (UTHM) were low in shear strength, bearing capacity, and suffer large settlements when subjected to loading. They undergo varies of dynamic cyclic loadings during their design lifetime and the response was typically more complex, requiring engineers to investigate the dynamic behaviour of soils thoroughly in the laboratory. The objectives of this research were to simulate remolded Batu Pahat Soft Clay (RBPSC) samples with different σv’, to study the dynamic shear modulus, G and damping ratio, D of (RBPSC) under cyclic loading with different f, OCRs, σv’ and σc’ and to analyses the correlation between G and D of the (RBPSC) with the OCR values under cyclic loading. As result, the 100 x 50 mm of remoulded samples are succeed simulated by using large strain consolidation apparatus of 50, 80 and 100 kPa of pre consolidation stress, contain moisture ranging within 42 to 55%. The series of remolded consolidated undrained dynamic cyclic triaxial test were ran under OCR of 1, 2, 3.85 and 4. Hence, it could be concluded that the G decreased when increasing of f and OCRs subjected to increasing axial strain while the G corresponding to each σv’ increases slightly as the σv’ becomes higher. The D shows minor increased when increasing of the f, OCRs and σv’ when subjected to increasing axial strain. Thus, input of parameter G and D can be review as technical values to key design structure on top of soil layer

The New Biodegradable Surfactant Drilling Fluid for Offshore HPHT Drilling Environment

The global growing demand for energy has driven oil and gas industry towards drilling deeper wells, many which are subjected to high pressure and high temperature (HPHT) (Burdyn and Wiener, 1956; Larsen, 2007, Godwin et al., 2011). However, this development of deeper oil horizon is halted when conventional drilling fluids are unable to withstand these high temperatures (Burdyn and Wiener, 1956; Darley and Gray, 1988; Woha and Joel, 2011). Polymers (mud additives) degraded at elevated temperature and this causes unsatisfactory performances (Burdyn and Wiener, 1956; Darley and Gray, 1988). The work was carried out to find the application of non-ionic surfactant used for Enhanced Oil Recovery (EOR)’s Polyethylene glycol (PEG) 550 based surfactant in drilling fluid. The focus will be put on the improvement of high pressure high temperature (HPHT) stability of conventional polymer, suspending agent (Xanthan Gum) and filtration reduction agent (PAC-LV) with the existence of surfactant. The rheological and filtration properties of the drilling fluids were acquired using standard testing apparatus, viscometer and API filter press respectively. The performances were later evaluated with comparison with drilling fluids without surfactant. It was observed that surfactant drilling fluids still exhibited slightly higher value in viscosity compared to base fluids after hot-rolling at elevated temperatures. Besides, it also showed a remarkable reduction in fluid loss by almost half even after undergone hot-rolling up to 125°C. These results showed that PEG550 had the potential to be used in offshore HPHT drilling environments

Single- and Multiple-Shell Uniform Sampling Schemes for Diffusion MRI Using Spherical Codes

In diffusion MRI (dMRI), a good sampling scheme is important for efficient acquisition and robust reconstruction. Diffusion weighted signal is normally acquired on single or multiple shells in q-space. Signal samples are typically distributed uniformly on different shells to make them invariant to the orientation of structures within tissue, or the laboratory coordinate frame. The Electrostatic Energy Minimization (EEM) method, originally proposed for single shell sampling scheme in dMRI, was recently generalized to multi-shell schemes, called Generalized EEM (GEEM). GEEM has been successfully used in the Human Connectome Project (HCP). However, EEM does not directly address the goal of optimal sampling, i.e., achieving large angular separation between sampling points. In this paper, we propose a more natural formulation, called Spherical Code (SC), to directly maximize the minimal angle between different samples in single or multiple shells. We consider not only continuous problems to design single or multiple shell sampling schemes, but also discrete problems to uniformly extract sub-sampled schemes from an existing single or multiple shell scheme, and to order samples in an existing scheme. We propose five algorithms to solve the above problems, including an incremental SC (ISC), a sophisticated greedy algorithm called Iterative Maximum Overlap Construction (IMOC), an 1-Opt greedy method, a Mixed Integer Linear Programming (MILP) method, and a Constrained Non-Linear Optimization (CNLO) method. To our knowledge, this is the first work to use the SC formulation for single or multiple shell sampling schemes in dMRI. Experimental results indicate that SC methods obtain larger angular separation and better rotational invariance than the state-of-the-art EEM and GEEM. The related codes and a tutorial have been released in DMRITool.Comment: Accepted by IEEE transactions on Medical Imaging. Codes have been released in dmritool https://diffusionmritool.github.io/tutorial_qspacesampling.htm

The Feasibility of Optimal Currency Area for ASEAN after adopting the ASEAN Economic Community Blueprint in 2008

This paper investigates the feasibility of OCA for ASEAN after the implementation of ASEAN Economic Community Blueprint in 2008. Dynamic Conditional Correlation (DCC) model with and without a structural break are used to identify whether the policy implemented facilitates the region to move closer to a single currency area. Industrial production index growth rate and change in short-term interest rate for ASEAN founders (Indonesia, Malaysia, Philippines, Singapore, and Thailand) from the period of 2001-2013 are selected as a proxy for OCA and Maastricht criteria respectively, which are cited as significant factors for successful functioning of OCA. The results show that there is a structural break for most conditional correlation of country pairs of the two variables after the implementation of integration policy in 2008 and that most of the conditional correlations decrease over time. The results imply that the whole region diverges away from OCA and Maastricht criteria and that the feasibility of OCA is decreased. As discussed by a number of previous researches regarding the issue, there is a possibility that higher economic integration resulted from integration policy may cause economic divergence due to specialization in industry of country members. For higher effectiveness of future integration policy formulation, a formal quantitative testing is required in order to precisely identify that higher economic integration causes higher specialization in the industry and, hence, more divergence in business cycle

Topics In Time Series Analysis And Forecasting

This thesis contains new developments in various topics in time series analysis and forecasting. These topics include: model selec- tion, estimation, forecasting and diagnostic checking.;In the area of model selection, finite and large sample properties of the commonly used selection criteria, Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC), are discussed. In the finite case, the study is limited to the two sample problem. The exact probability of selection is obtained for finite samples. The risk of each criterion is evaluated in the two sample situation. Empirical evidence regarding these risks are given for autoregressive processes. The asymptotic distribution of the (\u27)h is given, where (\u27)h is the estimate of the number of extra parameters in the model selected by the AIC criterion. This derivation is based on large sample properties of the likelihood ratio test statistic. The asymptotic distribution of the AIC in PAR models is also discussed.;In estimation, an explicit expression for the efficiency of strongly consistent estimates for the ARMA(1,1) model is derived. Empirical efficiency and the empirical estimate are examined by simulation.;On the topic of forecasting, the asymptotic variance of the fore- cast error is derived for an autoregressive model of first order. In the derivation, the estimated parameter is not assumed to be independ- ent of the data. The variance of the one-step forecast error is also derived for the fractional noise model.;In the last topic, empirical results for portmanteau test statistics are studied. It is shown that the modified Portmanteau test of Ljung and Box (1980) outperforms the modified test of Li and McLeod (1981). In testing for whiteness, the modified Portmanteau test is shown to have lower power than the cumulative periodogram test against both fractional noise and standard ARMA alternatives

Attainment Of Desired Magnetic Properties Of Mg-Zn Ferrite By Controlling The Composition And Microstucture

This research work was conducted to investigate and understand better the characteristics of magnesium based ferrites. Magnesium-based ferrites were chosen due to one of their vital characteristics, that is high electrical resistivity, which can make them better materials at higher operating frequencies. Besides, they have a lower production cost and no environmental effect. Therefore, perhaps, they can be a better substitute to the existing technological ferrites and consequently replacing them. In order to achieve these goals, a wide-scope experimental investigation was conducted . The samples were prepared by the oxide ceramic processing method, involving dry mixing and solid state reactions. The experimental investigation covered the effects of compositional variations in magnesium-based ferrites with iron deficiency, excess zinc, iron deficiency with excess zinc, magnesium-zinc ion exchange and magnesium-iron ion exchange. Additional experimental work was also carried out to study the effects, on microstructure, of the grinding time, pre-sintering temperature, sintering temperature and sintering time. It was found that, in general, iron deficiency and excess zinc was beneficial to obtaining good magnetic properties. For the magnesium-zinc and magnesium-iron ion exchange, there existed particular compositions which yielded optimum magnetic properties

An EPiC Solution to Teacher Education : Working with Constraints

This paper focuses on explaining how the Faculty of Education and Languages, Open University Malaysia (OUM) works around constraints and policies set by the Ministry of Education of Malaysia (MOE) in its effort to upgrade the qualification of the in-service teachers enrolled in the Bachelor of Teaching programme. In line with the government’s policy to increase human capital development MOE introduces new elements which are to be incorporated into the existing teachers’ training curriculum. For OUM it means finding solutions to add another 15 credits to the existing programme without extending the duration of the whole programme. To meet this new challenge, a new approach is needed to comply with MOE’s requirements. Education Portal for Internet Courses (EPiC) is created not only to meet the new requirements but also to add value to the existing programme. It is designed to virtually extend students’ learning space and to provide full online learning and support. Its activities are scaffold, assignments are task based and learning draws on students’ experience and personal reflections. The whole environment is designed to be fun and promote active collaboration between students and their online supervisors. (Abstract by author

Collagen-hyaluronic acid scaffolds for adipose tissue engineering.

Three-dimensional (3-D) in vitro models of the mammary gland require a scaffold matrix that supports the development of adipose stroma within a robust freely permeable matrix. 3-D porous collagen-hyaluronic acid (HA: 7.5% and 15%) scaffolds were produced by controlled freeze-drying technique and crosslinking with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride. All scaffolds displayed uniform, interconnected pore structure (total porosity approximately 85%). Physical and chemical analysis showed no signs of collagen denaturation during the formation process. The values of thermal characteristics indicated that crosslinking occurred and that its efficiency was enhanced by the presence of HA. Although the crosslinking reduced the swelling of the strut material in water, the collagen-HA matrix as a whole tended to swell more and show higher dissolution resistance than pure collagen samples. The compressive modulus and elastic collapse stress were higher for collagen-HA composites. All the scaffolds were shown to support the proliferation and differentiation 3T3-L1 preadipocytes while collagen-HA samples maintained a significantly increased proportion of cycling cells (Ki-67+). Furthermore, collagen-HA composites displayed significantly raised Adipsin gene expression with adipogenic culture supplementation for 8 days vs. control conditions. These results indicate that collagen-HA scaffolds may offer robust, freely permeable 3-D matrices that enhance mammary stromal tissue development in vitro.This was supported by the Biotechnology and Biological Sciences Research Council