Al-Nahrain Journal for Engineering Sciences

The aim of this research is to investigate how fiber orientations in composite materials used in aircraft applications increase mechanical properties. Consideration was given to two different fiber-to-matrix ratios in order to improve the mechanical properties. The materials used for fabrication are graphite powder (2.12 g/cm3), carbon fiber Sikawrap-301 C, E-glass fiber EWR450, and aluminum alloy sheet 2024–T3. In this study, carbon fiber, glass fiber, and glass carbon fiber specimens are created by hand lay-up for testing. The fiber orientation and fiber-to-matrix ratio were used to create these specimens. On universal testing machines (UTMs), tensile and flexural tests were performed on the sample. Tensile testing is done at three different angles on a sample: 0°, 45°, and 90°. The results of tensile tests first show that the strength of the double layer of carbon fiber-reinforced polymer CFRP reduces with increasing fiber orientation. Second, the highest stress a material can resist for the three samples made up of a single layer is 45°. For flexural tests, a three-point bend at 45 degrees demonstrates excellent strength for carbon fiber compared with glass carbon fiber and glass fiber. The results show that fiber orientation improves the composites' mechanical properties and increases adhesion. Carbon fiber-reinforced aluminum laminates are lighter than aircraft wing alloy 2024-T3.

In this study, the mechanical properties of an epoxy, unidirectional woven carbon and fiberglass composite were investigated experimentally. ASTM used for preparing the composite specimen. Different ranges of mixing ratios of woven carbon and fiberglass with epoxy are studied. Tensile, impact and bending test are carried out to investigate the mechanical properties for produced new composites. After testing the mechanical properties of the specimens, it is noted that adding of unidirectional woven carbon layers will leads to strengthens the samples. The mechanical properties of woven carbon composite are far superior to those of woven carbon composite with fiberglass.

The fifth generation (5G) and beyond mobile networks support increasing number of users with increasing bit rate per user. This has encouraged researchers to propose coherent digital subcarrier multiplexing (SCM) point-to-multipoint (P2MP) architectures to reduce the cost and complexity of optical transport networks, particularly in the metro aggregation scenario. However, coherent optical receiver is relatively cost and complex compared with a direct-detection (DD) counterpart due to the use of a synchronized local laser. This paper addresses design issues and performance investigation of intensity modulation/direct-detection (IM/DD) P2MP optical networks. P2MP architectures are designed using digital RF multisubcarrier (MSC) waveform embedded on the intensity of continuous-wave (CW) laser beside direct-detection scheme. The design covers covers Conventional-band (C-band) and Original-band (O-band) operation using a wavelength-division multiplexing (WDM) architecture. Further single- and double-polarization (SP and DP) versions are reported for each type of the networks. All the architectures are built in Optisystem version 15 environment and simulated for different network parameters, under the assumption of 25 Gbps per subcarrier data rate. The main performance measures are maximum route reach and bit rate-distance product (BDP). The simulation results indicate that DD networks can replaced the coherent counterpart when number of subcarriers per optical channel is 4. Further, the O-band P2MP networks offer high values of maximum reach and BDP than C-band counterparts.

As a result of the tremendous development taking place in modern systems and technologies in the field of electronic monitoring. Intelligent monitoring, decision making, and automated response systems have become common subjects at this time, especially after the development of machines responsible for these processes. Traffic surveillance is a trend goal nowadays using different techniques and equipment. In this article, real-time Object detection and tracking techniques were proposed for traffic surveillance using image processing techniques. A state was specifically examined for its ability to detect and count passing motorcycles on a highway in a specific area. The results showed good reliability, with a frame processing time of approximately about (30 ms) and the achievement of real-time performance. The main contribution of this article is reaching the best result implemented by the performance the real-time process using image process technique and tracking the object by depending on the sequencing of frames and can stands with rationally not so powerful machines. Several tools have been used for different types of necessary tasks that will be part of the required application such as Python 3.7; which was used to build the basic algorithms,Visual studio code (VSC) as an Integrated Development Environment (IDE), and Anaconda navigator for downloading many useful libraries. The specifications of the used device were Intel(R) Core (TM) i7- 10750H CPU @ 2.60GHz 2.59 GHz, RAM 16.0 GB, NVIDIA GeForce GTX 1650 GPU, 64-bit operating system, x64-based processor.

Rutting is the most common distress that most Iraqi asphalt pavements suffer from it. Asphalt binders are modified by using additives and polymers to enhance their physical qualities and fulfill the performance demands. Polyphosphoric acid (PPA) has been used in many countries to enhance the physical and mechanical characteristics of asphalt binders and mixtures that can improve the performance of asphalt pavements. In this paper, evaluation of the Iraqi asphalt binder and mixtures performance by using three percentages of Polyphosphoric acid (PPA) (0.4, 0.8, and 1.2) percent by asphalt binder weight and added to (60-70) penetration grade asphalt binder to show the applicability and suitability of using PPA in asphalt pavement in Iraq. Original asphalt binder and modified are subjected to traditional tests which are penetration, ductility, softening point, and viscosity. Results show better performance and enhancement of the physical properties of the modified binder. Other tests are Marshall Stability and wheel track tests. The results of the addition of PPA to the asphalt mixture show increases in the Marshall Stability and enhance the performance of the asphalt pavement mixtures. The wheel track test is applied to the original and modified mixture at two test temperatures 40οC and 50οC and the results show a decrease in the rut depth when the percentages of PPA increase. It is concluded that %PPA addition will enhance the performance of the Iraqi asphalt pavement and the mixture will be more rutting resistant, especially in high-temperature weather.

Recently, there is increasing interest in using the 18 THz bandwidth offered by S+C+L band to increase the transmission capacity of fiber communication systems. This leads to the generation of ultra-wideband (UWB) wavelength-division multiplexing (WDM) optical communication systems. In these advanced systems, stimulated Raman scattering (SRS) causes a power transfer from high-frequency channels to low-frequency channels. This effect leads to an increase in the nonlinear interference (NLI) between the UWB-WDM channels. Power optimization techniques are required to balance transfer power between band channels, thus increasing the maximum transmission reach (MTR) along with increasing system capacity. In this paper, the transmission performance of S+C+L band system operating with dual-polarization 16-QAM signaling is investigated using enhanced Gaussian noise model. The transmitter and receiver for each DP channel use a 45^o-polarized laser and incorporate two identical configurations, one for x- and the other for y-state of polarization (SOP). The results are presented for two values of symbol rate, 40 and 80 GBaud, where the system carries 360 (=160+80+120) and 180 (=80+40+60) channels, respectively. The results revel that the MTR of both cases is equal to 12 100 km-spans when the channel lunch power equals to -4 and -2 dBm, respectively. This work also shows the effect of NLI components as a function of the number of spans, channel spacing, and channel launch power. The results show that the cross-phase modulation component of the NLI has high accumulated value with transmission distance, while the self-phase modulation component is almost constant.