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Study the hardness and temperature changes during tooth bleaching using different Laser Sources

Authors: ZainabM. Abdul-Ameer --- Abdulla K. Abass --- Sinan M. Abdul-Satar
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2010 Volume: 22 Issue: 4 Pages: 41-46
Publisher: Baghdad University جامعة بغداد


Background: Today, the processes of teeth bleaching by utilizing oxidation chemical components became a public
and important as a cosmetically operative. Particularly the demanding on these processes increased with the
developing in bleaching techniques, where laser light is used as catalyzer agent to increasing the efficiency and
speed of these processes, and the latter known as office bleaching. In this paper, we evaluate the effect of different
laser wavelengths of bleaching on the surface hardness of the tooth and the temperature rise of the pulp due to the
influence of laser light in conjunction with the bleaching gel.
Materials and methods: Three different laser sources (KTP 532nm, LD 810nm and Nd:YAG 1064nm) were used as
accelerator agent in-office bleaching utilizing Hydrogen Peroxide at 37.5%, where the enamel micro hardness
measurements in the teeth (invitro study) pre and post operative was done.
Results: Then by using analysis of variance (ANOVA-Tukey’s test r = 0.05 ) the results shows there are insignificant
effects on tooth hardness due to the changes in the laser wavelengths in both pre and post bleaching.
Conclusion: Thereafter to evaluate the pulp chamber temperature rise induced by three different light sources
employed in this laser-activated tooth bleaching, the pulp chamber temperature was measured during the radiation
processes and the results shows that the minimum temperature rise was seen at the 532nm. So, we can say that the
KTP (SHG) Nd:YAG laser at the wavelength (532 nm) represent the best choice to use in-office bleaching processes.
Keywords: Hardness, Tooth Bleaching, (SHG) Nd:YAG laser, (J Bagh Coll Dentistry 2010;22(4):41-46).


Mitigate PAPR Effect in Optical Orthogonal Frequency Division Multiplexing Using Companding Technique

Authors: Mohammed A. Husein --- Sinan M. Abdul Satar --- Ali n. Kareem
Journal: IRAQI JOURNAL OF COMPUTERS,COMMUNICATION AND CONTROL & SYSTEMS ENGINEERING المجلة العراقية لهندسة الحاسبات والاتصالات والسيطرة والنظم ISSN: 18119212 Year: 2018 Volume: 18 Issue: 3 Pages: 60-69
Publisher: University of Technology الجامعة التكنولوجية


orthogonal frequency division multiplexing (OFDM) is emerging asthe leading technology for high data rates. The OFDM based on multicarriertransmission that transforms a wideband channel into a group of thin-bandchannels. The high peak to average power ratio (PAPR) considers the maindrawback factor in this system, so the companding technique modifies theamplitude of OFDM signal to reduce this factor. The proposed A-lawcompanding technique has been implemented in intensity modulation/directdetection optical orthogonal frequency division multiplexing (IM/DDOOFDM).The proposed companding scheme guarantees the improvedperformance in terms of bit error rate (BER) and quality factor (QF) whilereducing PAPR effectively and efficiently by modifying the amplitude of thetransmitted signals. Our results confirm that the suggested scheme exhibits agood ability to reduce PAPR and a good BER performance based on the use theA factor. At the complementary cumulative distribution function (CCDF) of 10-3, the PAPR value of our proposed scheme is about 4.4 dB lower than those ofun-companded signal at best control factor used of A at 87.6, accordingly theQF is 2.5 dB and the BER is 6.2×10-3 at a distance 900km without anyequalization technique or training sequence or any channel estimation.

PAPR Reduction in Coherent Optical OFDM System using Modified Sliding Norm Transformer


Orthogonal Frequency Division Multiplexing is one of the mostimportant multiple carrier modulation format, which has many applications inwireless communication and optical communication. It is considered as anexcellent method for fast optical communication inferable from its high spectralefficiency and its strength to path losses. Peak to average power ratio isregarded as one of the main problems that are experienced by the opticalorthogonal frequency division multiplexing system, which directly affects thecharacteristics of the system. The current paper proposes an efficient techniqueto reduce Peak to Average Power Ratio by the modified Dursun’s method or theso called modified discrete sliding norm transformer in coherent opticalorthogonal frequency division multiplexing system for the first time to the baseof our knowledge consequently. The proposed technique does not need to sendside information to the receiver; also, it does not degrade bandwidth. Thisalgorithm lessens Peak to Average Power Ratio in the optical coherentOrthogonal Frequency Division Multiplexing system to about 4.15 dB atcomplementary cumulative distribution function (CCDF) probability of 10-3 andimproves the system performance.

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