Anbar Journal of Engineering Sciences

Previous studies showed that fire incidents cause a
considerable deterioration of limestone samples'
engineering and physical properties. Various laboratory
tests were used in previous studies to investigate the
properties of limestone. These tests included destructive
and non-destructive tests like the hammer test, ultrasonic
pulse velocity test, water-capillary rise test, and water
transfer properties test, as well as destructive tests like
the unconfined compression test and Brazilian tensile
test. The stones of buildings exposed to fire are
occasionally assessed on the site. This study analysed the
physical and mechanical changes that occurred to the
limestone samples when subjected to high temperatures,
the damage mechanism, and laboratory or field damage
assessment. This study also includes a review of the most
significant studies that looked at how alternative cooling
techniques—rapid water cooling or gradual air cooling—
affect stone samples subjected to high temperatures and
compared the behaviour of the samples in each scenario.

Solar cells play a vital role in renewable energy systems, and ongoing
research is dedicated to enhancing their power efficiency and longevity.
Advancements in perovskite solar cells, particularly in power
conversion efficiency (PCE), have shown significant progress,
confirming its viability as a technology. Perovskite solar cells have
achieved power conversion efficiency (PCE) levels of up to 25.5%,
comparable to conventional photovoltaic technologies like silicon,
gallium arsenide, and cadmium telluride. The substantial enhancement
in power conversion efficiency figures over the last decade has shown a
remarkable advancement in the efficiency of perovskite solar cells. This
study examines the trajectory of perovskite solar cells in becoming
economically feasible and generally embraced as a critical renewable
energy technology. The advancement of flexible and wearable solar
cells, together with miniature solar-powered sensors, has increased the
efficiency of solar cell power production. Perovskite solar cells have
shown a specific power of 23 W/g, much higher than traditional silicon
or gallium arsenide solar cells. Further research is needed to address
the challenges related to perovskite solar cells' stability and power
conversion efficiency. Perovskite solar cells integrated with energy
storage units have the potential to enhance the overall efficiency of the
system. This study discusses an approach to improve the efficiency of
novel solar cells, specifically focusing on lead-free tin-based perovskite
solar cells and tandem solar cells. The advancement of technology in
thin films, such as hybrid nanocomposite thin films and quantum dotsensitive solar cells, has the potential to improve the efficiency of solar
cells. The primary outcome of this study is derived from the following
inference: incorporating plasmatic nanostructures into thermal energy
systems will enhance their efficiency and sustainability by integrating
solar energy

In this current experimental research, the amount of
improvement in the thermal conductivity of HEC hybrid epoxy
resins was studied by adding copper oxide nanoparticles CuONp
and carbon nanotubes (CNTs) as hybrid additives in different
proportions to select the sample with the highest thermal
conductivity value to include it in the design of the Flat Plate
Solar Collector FPSC as Thermal Interface Material TIM reduces
thermal resistance between the absorber plate and the tube.
Four groups of samples were prepared using a mass balance
with a sensitivity of 0.01g and a magnetic mixing device, then
poured into cubic plastic molds to take the shape of the sample.
The first group consists of one sample of pure epoxy to calibrate
the thermal properties testing device through it. The second
group consists of five samples of epoxy loaded with CNTs by
weight (1, 3, 5, 7.5, 10) %. The third group consists of five
samples of epoxy loaded with CuONp with weight percentages of
(1, 3, 5, 7.5, 10) %. The fourth group consists of five samples of
epoxy loaded with CuONp and CNTs combined in weight
percentages of (1, 3, 5, 7.5, 10) %. The thermal conductivity of
the samples was measured experimentally using the hot disk
analyzer technique to measure thermal specifications. After
comparing the thermal conductivity values of the samples, the
highest value was 1.57 W/mK for the HEC sample loaded with
10% CNTs, which represents 9.23 times higher than pure epoxy.

The direct sequence (DS) spread spectrum
communication technique is widely regarded as one of
the most effective methods of mitigating the effects of a
repeating jammer in military communications systems.
The proposed system coupled DS with multiple
frequency shift keying (DS/MFSK). It is comprised of a
transmitter and a receiver. Non-coherent demodulation
is examined, as are the spreading sequences in question.
The effect of AWGN and Rayleigh fading channels on the
proposed approach's bit error rate (BER) is examined.
The investigation demonstrates that even with an 8 dB
signal-to-noise ratio, superior outcomes can be achieved;
this study's suggested endeavor is to create a novel
transceiver system built on the DS/MFSK modular
architecture. MFSK modulation prevents multiple-access
interference, while DS is typically employed to boost
system efficiency across erratic fading. Test results show
that reliability on the AWGN channel decreases a little
while reliability is greatly enhanced by Rayleigh fading.
Moreover, notable improvements in bandwidth
efficiency are achieved.