Life-cycle of fatigue sensitive structures under uncertainty

Fatigue is the one of the main contributors to problems related to structural safety of civil and marine structures. Life-cycle management (LCM) techniques considering various uncertainties can be used to predict the safe service life of fatigue sensitive structures, plan for their future inspections and support the decision making process regarding maintenance and repair actions. This paper provides a brief overview of the LCM of fatigue sensitive civil and marine structures under uncertainty. Probabilistic performance prediction, inspection scheduling and maintenance optimization for such structures are discussed

Audit Committee Effectiveness, Audit Quality and Earnings Management: An Empirical Study of the Listed Companies in Egypt

The role of audit committees and audit quality in ensuring the quality of corporate financial reporting has come under considerable scrutiny due to recent high-profile earnings management cases in the world. The purpose of this paper is to examine the association between the audit committee effectiveness, audit quality and earnings management practices of more active 50 Egyptian companies listed on the Egyptian Stock Exchange of the non-financial sector during the period 2007-2010. After controlling for size, leverage and cash flow from operation activities, the results of univariate and multivariate analyses indicated that audit committees independence; experience of audit committee members; audit committee meetings; and audit quality have significant negative association with discretionary accruals as a proxy for earnings management. On the other hand, no significant relationship is found between audit committees size and the level of discretionary accruals. This paper is important because it offers useful information that is of great value to policy makers, academics and other stakeholders. Keywords: Audit Committee Effectiveness, Audit Quality, Earning Management, Egyp

Maintenance and safety of deteriorating systems: a life-cycle perspective

This paper reviews the key aspects associated with maintenance and safety of deteriorating infrastructure systems from a life-cycle perspective. The main conceptual aspects related to probabilistic optimization of maintenance and rehabilitation of structural systems are discussed. These aspects include life-cycle risk and sustainability assessment, risk-informed and utility-based decision making, and multi-objective optimization of interventions. In general, sustainability assessment is performed by quantifying economic, social, and environmental impacts associated with infrastructure management activities. This keynote paper also reviews various methods for determining optimum life-cycle maintenance, repair, and rehabilitation types and times, as well as the impact of such activities on the total life-cycle cost. The role of probabilistic performance indicators including reliability and risk, the sustainability assessment of deteriorating infrastructure systems, and risk- and utility-informed decision making are highlighted herein

Optimum Remedial Operation of Permanent Magnet Synchronous Motor

In critical systems, the reliability of the drive is very important. The faults are unwanted. The faults may be lead to loss of the human life and capital. This paper is addressed this problem and suggested two models to solve it. The first model doesn’t contain any special tools to improve the torque ripple and THD. The second model contains 2PI current controllers to improvement the performance at fault and remedial operation. One is for the torque and the other is for the flux. The first PI controller is feeding from the torque error between the reference and estimated torques to get new q-axis current component representing modifier current arises from uncertain things inside the machine and drive system such as temperature and parameters variations. This current will add to reference q-axis current to get robust new q-axis current to satisfy the drive requirement and solve the torque problem (ripple torque). With robust current, the total harmonic distortion is a decrease but doesn’t reach the best value so the other PI controller is used to adjust the THD. In this PI controller, the d-axis flux is compared to rotor permanent magnet flux to solve this problem arises from non-sinusoidal of the magnetic flux. The output of the PI controller is introduced to the reference d-axis current. The new d-axis current will reach the best value of THD. The simulation of the second controller is compared to the simulation of first controller to show if the second controller strong or weak. Matlab simulink is used to simulate the drive system.DOI:http://dx.doi.org/10.11591/ijece.v2i5.72

Bees visiting the broad bean (Vicia faba L.) and the impact of border planting on their abundance and the yield improvement in Ismailia, Egypt:

Incorporating flowering plants into cropping systems has the potential to actively enhance pollination and crops yields. This study evaluated whether the introduction of border planting affects bee visitation and yield of a broad bean (Vicia faba L.). Experiments were carried out in 2018 and 2019 in Ismailia, Egypt.  Bee visitation and broad bean yields were compared between plots with and without border planting. Results showed that open flowers achieved higher yields than netted flowers. Apis mellifera L. was the dominant visitor, followed by four solitary bee species, Chalicodoma siculum (Rossi), Colletes lacunatus Dours, 1872, Andrena ovatula and Xylocopa pubescens (Kirby, 1802).  The addition of border planting was associated with a significant increase in the abundance of all five bee visitors and the associated yields. Findings showed that flowering border plants adjacent to broad bean can actively enhance pollination services and yields of this commercially valuable crop, whilst helping to conserve vulnerable bee populations

MAT-741: IMPACT BEHAVIOUR OF SHAPE MEMORY ALLOY HYBRID FIBRE-REINFORCED ENGINEERED CEMENTITIOUS COMPOSITE

An experimental study was conducted to evaluate the impact behaviour of an innovative hybrid-fibre engineered cementitious composite (ECC) incorporating randomly dispersed short shape memory alloy fibres (SMA). A modified drop weight test was conducted on specimens from various ECC mixtures with and without SMA fibres. The impact behaviour was evaluated and compared based on the ability to dissipate energy and sustain impact load without damage. Results show that the addition of SMA to ECC mixtures significantly enhanced their performance under impact loading. The amount of dissipated energy by ECC increased by about 51% as a result of SMA fibre addition. This highlights the potential benefits of incorporating SMA in composite materials exposed to impact loads, paving the way for a wider implementation in the field of fortified structures

Fatigue reliability and service life prediction of aluminum naval ship details based on monitoring data

The evolution of naval vessels towards high-speed crafts subjected to severe sea conditions has promoted an increasing interest in lightweight high-strength materials. Due to its strength and weight characteristics, aluminum has been proven especially suitable as construction material for hull structures, as well as other vessel parts. However, fatigue in aluminum naval crafts needs to be effectively addressed for the proper life-cycle assessment. Structural health monitoring (SHM) systems constitute effective tools for measuring the structural response and assessing the structural performance under actual operational conditions. In this paper, an approach for using SHM information in the fatigue reliability analysis and service life prediction of aluminum naval vessels is presented. The accumulated fatigue damage and the fatigue reliability are quantified based on SHM data acquired under different operational conditions, specified by the ship speeds, sea states, and heading angles. Additionally, an approach for estimating the reliability-based fatigue life under a given operational profile is presented. Seakeeping trial data of an aluminium high-speed naval vessel are used to illustrate the proposed approach

RT-PCR ANALYSIS OF GENES EXPRESSION TO EVALUATE THE BIOMEDICAL IMPORTANCE OF MEDICAL-HERBAL EXTRACTS IN DIABETES TREATMENT

Fenugreek is an annual crop belonging to the legume family grown in most parts of the world. It is known to possess a number of medicinal properties, but a little phytochemical research has been carried out on the seeds of species; Trigonella hamosa Leguminosae. Previously we reported that Trigonella seeds extract are shown to have hypoglycemic effects on experimental diabetic rats. The aim of the current study is to understand the molecular mechanism of antidiabetic actions of Trigonella. Therefore, we examined the expressions levels of genes involved in glucose metabolism in liver of diabetic rats. Upon this basis, streptozotocin (STZ)-diabetic rats are used to assess hepatic glucokinase (GCK), insulin like growth factor-1 (IGF- 1), and glucose transporters (GLUT-2) genes expressions after Trigonella administration by oral intragastric intubation for two months, using RT-PCR assay. The current findings demonstrated that Trigonella reduced significantly glucose level in diabetic rats, while significantly increases insulin serum level. GCK expression levels in hepatic tissue of diabetic-rats are found to be suppressed, while Trigonella treatment induces an increase in hepatic GCK activity. Diabetes due to STZ has a little effect on IGF-1 gene expression, while Trigonella administration elevates mRNA expression significantly. On the other hand, Trigonella reduce and normalize the elevation of GLUT-2 gene expression, which increased due to STZ treatment. These results indicated that Trigonella are powerful antidiabetic agent, induce hypoglycemia by up-regulation of CGK and IGF-1 genes expression and induce an insulin mimetic activity