Today the use of composite materials in different kinds of applications is accelerating rapidly. Composite materials have become common engineering materials and are designed and manufactured for various application. This paper involves an experimental program including testing the capabilities of hybrid material s (composite and metallic materials) as an energy absorber. The method of approach has been to fabricate and test a series of specimens. The specimens have cylindrical shape; they are fabricated using hand lay-up technique. Hybrid specimens involve two subtypes: metallic cylinder surrounded by three layers of composite cylinder referred as M/C, and three layers of composite cylinder form the internal part surrounded by metallic cylinder referred as C/M (Fig.1). Hybrid model are subjected to lateral quasi static compression load.

• Pavement distress is an indication of pavement layer deterioration. There are many types of deterioration; however, rutting, defined as the permanent deformation forming longitudinal surface depressions in the wheel paths, is one of the most important kinds of distress that affect the safety and the ride quality of flexible pavement. The main objective of this study was to develop an empirical pavement rutting model for the wet freeze zone, which is one of the four long term pavement performance (LTPP) climate zones, to predict the depth of pavement rutting on granular bases. Using the LTPP database, the study aimed at a better understanding of the pavement rutting phenomena and the factors that may affect pavement rutting. Multiple regression analysis was performed to develop a flexible pavement rutting model. The proposed model was developed based on the relationship between the response variable rut depth and predictor variables of traffic loads, structural number, Marshall stiffness, air voids in the total mix, and voids in the mineral aggregate. It was found that traffic loads was the predominant factor that have a significant effect on pavement rutting, which agrees with the existing literature, as well as engineering knowledge and practice. Following the traffic loads, structural number was the most significant secondary factor, followed by percent of voids in the total mix, voids in the mineral aggregate, and Marshall stiffness.

This research presents the effect of corrugation geometry on the crushing behavior, energy absorption, of woven roving glass fiber/epoxy laminated composite shells. Experimental investigations were carried out on three geometrical different types of composite shells subjected to compressive loadings. The results showed that the loading carrying capability is significantly influenced by corrugation geometry in axial crushing. Load–displacement curve was plotted for all conducted tests

neural network is considered as a nonlinear dynamic system consisting of a large number of simple processing elements interconnected in some manner with adjustable weighted strength. Neural networks provide qualitative and quantitative (analog, digital or logical) knowledge through information coding and decoding, and have powerful functions in learning and selforganization. These properties make neural networks considered to be more powerful in dealing with numerical data than other artificial intelligent systems like expert systems. However, the performance of neural networks depends deeply in number of factors including transfer function, number of hidden layers, number of nodes in hidden layers, input function, and weight function. In this article we present a comparative study of these factors and how they influence the performance of a system. 

The influence of physical (external added weight) and neurophysiological (fatigue) factors on static and dynamic balance in sport related activities was typified statically by the Romberg test (one foot flat, eyes open) and dynamically by jumping and hopping in both horizontal and vertical directions. Twenty healthy males were participated in this study. In Static condition, added weight increased body-s inertia and therefore decreased body sway in AP direction though not significantly. Dynamically, added weight significantly increased body sway in both ML and AP directions, indicating instability, and the use of the counter rotating segments mechanism to maintain balance was demonstrated. Fatigue on the other hand significantly increased body sway during static balance as a neurophysiological adaptation primarily to the inverted pendulum mechanism. Dynamically, fatigue significantly increased body sway in both ML and AP directions again indicating instability but with a greater use of counter rotating segments mechanism. Differential adaptations for each of the two balance mechanisms (inverted pendulum and counter rotating segments) were found between one foot flat and two feet flat dynamic conditions, as participants relied more heavily on the first in the one foot flat conditions and relied more on the second in the two feet flat conditions.

The Muslim faith requires individuals to fast between the hours of sunrise and sunset during the month of Ramadan. Our recent work has concentrated on some of the changes that take place during the daytime when fasting. A questionnaire was developed to assess subjective estimates of physical, mental and social activities, and fatigue. Four days were studied: in the weeks before and after Ramadan (control days) and during the first and last weeks of Ramadan (experimental days). On each of these four days, this questionnaire was given several times during the daytime and once after the fast had been broken and just before individuals retired at night. During Ramadan, daytime mental, physical and social activities all decreased below control values but then increased to abovecontrol values in the evening. The desires to perform physical and mental activities showed very similar patterns. That is, individuals tried to conserve energy during the daytime in preparation for the evenings when they ate and drank, often with friends. During Ramadan also, individuals were more fatigued in the daytime and napped more often than on control days. This extra fatigue probably reflected decreased sleep, individuals often having risen earlier (before sunrise, to prepare for fasting) and retired later (to enable recovery from the fast). Some physiological measures and objective measures of performance (including the response to a bout of exercise) have also been investigated. Urine osmolality fell during the daytime on control days as subjects drank, but rose in Ramadan to reach values at sunset indicative of dehydration. Exercise performance was also compromised, particularly late in the afternoon when the fast had lasted several hours. Self-chosen exercise work-rates fell and a set amount of exercise felt more arduous. There were also changes in heart rate and lactate accumulation in the blood, indicative of greater cardiovascular and metabolic stress caused by the exercise in subjects who had been fasting. Daytime fasting in Ramadan produces widespread effects which probably reflect combined effects of sleep loss and restrictions to intakes of water and food.

This study is aimed at investigating the interactive effects of reaction parameters such as temperature (330–370 °C), total pressure (30–50 bar) and liquid hourly space velocity LHSV (1–3 h⁻¹) on the performance of hydrodesulfurization (HDS) activity. Experiments were performed based on the central composite rotatable design and analyzed using the response surface methodology (RSM). First, the equation model is used to predict HDS activity as a response. Second, the regression analysis of the HDS activity model is obtained from the output of this developed model. Finally, the RSM and canonical analysis is used to optimize this empirical regression model. R ² = 96.5 % showed that the RSM model fitted the observed data well with and is considered to be accurate and available for predicting HDS activity. The obtained equation for the canonical analysis with different signs of eigenvalues …

ABSTRACT

In order to capture the effect of joint progressive stiffness degradation with the hardening effect taken into account, the three parametric continuous model is adopted hereafter for the analytical formulation. The current paper is an extension of the previous work (Gizejowski et al. 2012) giving all the details of the developed model together with a calibration procedure for basic model parameters. Experimental data used was obtained from laboratory tests carried out at the Warsaw University of Technology for beam-to-column joints of different reinforcement ratio. The results of calibration exercise as well as the values of calibrated model parameters are given for practical application.