The paper presents studies on experimental investigation of beam-to-column joint behavior in standard and exceptional events situations. This assessment is done to form a picture of the general the behavior of full scale frameworks at both the level of the global behavior of the framework, in terms of its load-displacement characteristic, and of the local behavior of joints in terms of their moment-rotation characteristics, and evaluates details about the interaction of the joint elements and how they work together in a balanced manner, during exceptional events, this study concerns the joints which are subject to the collapse and also includes the behavior of joints in the neighborhood of the collapse. The intricacy of such investigations appear from nonlinear effects associated with the outlook of joint behavior or functioning, such as structural shortcomings, large displacements and rotations, inelastic properties of steel and concrete materials, the effects between steel and concrete, and slip between concrete and structural steel, through others. The paper addresses these problems using two types of joints flush and extended end-plate with four and eight bolts and provides recommendations and reasoning for the behavioral techniques for the evaluation of joint moment-rotation response when exposed to negative and positive moments together.

The paper presents studies on experimental investigation of beam-to-column joint behaviour in standard and exceptional events situations. This assessment is done to form a picture of the general the behavior of full scale frameworks at both the level of the global behavior of the framework, in terms of its load-displacement characteristic, and of the local behavior of joints in terms of their moment-rotation characteristics, and evaluates details about the interaction of the joint elements and how they work together in a balanced manner, during exceptional events, this study concerns the joints which are subject to the collapse and also includes the behavior of joints in the neighborhood of the collapse. The intricacy of such investigations appear from nonlinear effects associated with the outlook of joint behavior or functioning, such as structural shortcomings, large displacements and rotations, inelastic properties of steel and concrete materials, the effects between steel and concrete, and slip between concrete and structural steel, through others. The paper addresses these problems using two types of joints flush and extended end-plate with four and eight bolts and provides recommendations and reasoning for the behavioral techniques for the evaluation of joint moment-rotation response when exposed to negative and positive moments together.

АННОТАЦИЯ:

Through the last three decades, the Normalized Difference Vegetation Index (NDVI) has been widely used for vegetation mapping and monitoring land-cover change in semi-arid regions. In Libya semi-arid lands occupy many parts in the north part of country that is near the Mediterranean Sea. The aim of paper is to use remote sensing technique (NDVI) for monitoring vegetation degradation in Al-Jabal Al-Akhdar region in Libya. The Pathfinder AVHRR Land (PAL), SPOT Apparent green cover percentage data and MODIS Vegetation index are used to monitor the vegetation cover change in the study area. The paper explain the possibility of use only long term NOAA-AVHRR NDVI time-series data, without need to any precipitation data, for assessing desertification conditions in Al-Jabal Al-Akhdar region. According to annual rainfall the northern parts of the area receives the greatest amount of rainfall towards the Mediterranean Sea, which occurs between October and May, it agreed well with the spatial pattern of NDVI within monthly averaged of vegetation that start increasing rapidly and reached a greater amount during spring (March-May), and decreased during June to September...

This work is a continuation of a design of a phase radio navigation system for aircraft blind landing in case of nonequipped runways proposed in [1], where, the proposed system is based on measuring the phase shifts of signals received from four ground transmitters (antennas), placed on corners of the runway strip, which provide distance measurements accuracy in millimeters. However, there are two important points that need serious consideration. First, the phase measurement is going to give the total phase () ϕ ρ−

0, while the actual phase shift of interest is ‘ϕ’, 0 ρ is the transmitter initial phase. The second problem is that, the measured phase angle () ϕ ρ− 0 between the transmitted and the received signal can only be measured in the interval from 0 to π 2 radians, this problem is called phase ambiguity. The answer of these problems lies in the use of more than one frequency (signal). Two sinusoidal signals with different frequencies (1f and 2f) but the same initial phase can be used. Taking the difference of the measured phases, the initial phase 0 ρ can vanish. To get around phase ambiguity would be to make sure that the actual phase difference 12 ϕ∆ does not exceed π 2, this technique called equivalent or synthetic wavelength.

A new radio navigation system for aircraft blind landing is proposed. This system is based on measuring the phase shifts of signals received from four ground transmitters (antennas), placed on corners of the runway strip. The received signals phase shifts provide distance measurements accuracy in millimetres. The reception of these signals is made on the onboard antenna located on the aircraft. Three ground antennas out of the four will be sufficient for determining the location of the aircraft. As a result of the analysis, the coordinates of the onboard antenna, the coordinates of the centre of mass of the aircraft, and axis coordinate of the aircraft determined with respect to the runway coordinate system.

This work describes the architecture and design of an onboard digital receiver of the phase radio-navigation system for aircraft blind landing proposed in [1]. The proposed onboard digital receiver is a special case of a multi-channel narrowband digital receiver concept. The purpose of this receiver is to receive eight different RF frequencies (in four pairs) range from 960 MHz to 963.003749941 MHz, carry on them the required analogue and digital signal processing techniques to evaluate their phase shifts and then the difference phase shifts between each pair of them. The phase measurements lead to determination of the location of the aircraft with respect to the touch point on the runway with accuracy in millimetres.