An All-Optical Frequency Up/Down-Converter Utilizing Stimulated Brillouin Scattering In A Trf And Dcf For Rof Application

A frequency up and down conversion is proposed based on stimulated Brillouin scattering (SBS) for Radio-over-fiber (RoF) system. Microwave frequency up conversion from 2GHz to 12.5GHz and microwave frequency down conversion from 12.5GHz to 1.8GHz with largest Intermediate Frequency (IF) power of -32dBm is successfully demonstrated. The up conversion is based on the 1st Stokes of Brillouin fiber laser in Truewave reach fiber (TWF) and the down conversion is based on 1st AntiStokes of Brillouin fiber laser in Dispersion compensating fiber (DCF)

A comprehensive review of hydroxyapatite-based coatings adhesion on metallic biomaterials

Metallic biomaterials have been employed in replacing and reconstructing the structural parts of the human physical structure due to their high mechanical properties, superior biocompatibility, and high corrosion resistance. The most common metallic biomaterials that have been used in implants include magnesium, stainless steel, cobalt-based alloy, titanium, and titanium-based alloy. Hydroxyapatite (Ca10(PO4)6(OH)2) is one of the ceramic biomaterials considered as ideal materials for coating on metallic biomaterials as it possesses almost the closest similarity in chemical composition and excellent biocompatibility with natural bone tissue. Recently, the HAp-based coating has increasingly drawn attention to improve the adhesion quality in metallic biomaterials. This study comprehensively reviews the current progress in the adhesion qualities of HAp-based coatings on metallic biomaterials specifically for the biomedical application. It has been observed that a surface that meets the minimum unique characteristics will enhance the bonding force between the coating and metallic biomaterial as the substrate. Critical factors of coating/substrate materials, coating techniques, and coating thickness that determine the adhesion quality are thoroughly identified and discussed. The surface structure and microstructure of HAp-based coating are also reviewed to confirm the findings

Prediction error and accuracy of intraocular lens power calculation in pediatric patient comparing SRK II and Pediatric IOL Calculator

<p>Abstract</p> <p>Background</p> <p>Despite growing number of intraocular lens power calculation formulas, there is no evidence that these formulas have good predictive accuracy in pediatric, whose eyes are still undergoing rapid growth and refractive changes. This study is intended to compare the prediction error and the accuracy of predictability of intraocular lens power calculation in pediatric patients at 3 month post cataract surgery with primary implantation of an intraocular lens using SRK II versus Pediatric IOL Calculator for pediatric intraocular lens calculation. Pediatric IOL Calculator is a modification of SRK II using Holladay algorithm. This program attempts to predict the refraction of a pseudophakic child as he grows, using a Holladay algorithm model. This model is based on refraction measurements of pediatric aphakic eyes. Pediatric IOL Calculator uses computer software for intraocular lens calculation.</p> <p>Methods</p> <p>This comparative study consists of 31 eyes (24 patients) that successfully underwent cataract surgery and intraocular lens implantations. All patients were 12 years old and below (range: 4 months to 12 years old). Patients were randomized into 2 groups; SRK II group and Pediatric IOL Calculator group using envelope technique sampling procedure. Intraocular lens power calculations were made using either SRK II or Pediatric IOL Calculator for pediatric intraocular lens calculation based on the printed technique selected for every patient. Thirteen patients were assigned for SRK II group and another 11 patients for Pediatric IOL Calculator group. For SRK II group, the predicted postoperative refraction is based on the patient's axial length and is aimed for emmetropic at the time of surgery. However for Pediatric IOL Calculator group, the predicted postoperative refraction is aimed for emmetropic spherical equivalent at age 2 years old. The postoperative refractive outcome was taken as the spherical equivalent of the refraction at 3 month postoperative follow-up. The data were analysed to compare the mean prediction error and the accuracy of predictability of intraocular lens power calculation between SRK II and Pediatric IOL Calculator.</p> <p>Results</p> <p>There were 16 eyes in SRK II group and 15 eyes in Pediatric IOL Calculator group. The mean prediction error in the SRK II group was 1.03 D (SD, 0.69 D) while in Pediatric IOL Calculator group was 1.14 D (SD, 1.19 D). The SRK II group showed lower prediction error of 0.11 D compared to Pediatric IOL Calculator group, but this was not statistically significant (p = 0.74). There were 3 eyes (18.75%) in SRK II group achieved acccurate predictability where the refraction postoperatively was within ± 0.5 D from predicted refraction compared to 7 eyes (46.67%) in the Pediatric IOL Calculator group. However the difference of the accuracy of predictability of postoperative refraction between the two formulas was also not statistically significant (p = 0.097).</p> <p>Conclusions</p> <p>The prediction error and the accuracy of predictability of postoperative refraction in pediatric cataract surgery are comparable between SRK II and Pediatric IOL Calculator. The existence of the Pediatric IOL Calculator provides an alternative to the ophthalmologist for intraocular lens calculation in pediatric patients. Relatively small sample size and unequal distribution of patients especially the younger children (less than 3 years) with a short time follow-up (3 months), considering spherical equivalent only.</p

Development of 5S practice checklist for manufacturing industry

This paper explores the practical use of the 5S Checklist for environment, housekeeping and health, as well as safety improvement purposes at two manufacturing organizations. The main objective of this study is to assess the implementation of 5S and development of the 5S Activity Checklist in manufacturing companies. The scope for this study covers the following areas: identifying problems, looking into critical success factors, their outcomes and recommendations. In addition, factors that may act as constraints to the implementation of the 5S activity and possible solutions for the industries are also identified through observation and evaluation of the improved environmental performance. The study is conducted using a systematic approach with specific software in order to get the most accurate results. In conclusion, effective implementation of the 5S activity depends on the commitment of the top level management, total involvement of the staff at all levels within the company, function and background of the business, publicity given to the 5S activity and finally the training conducted for the organisation in implementing the 5S practices

Issues of Reading Habits Among Malaysian Students: School and Home Perceptions

Abstract: The purpose of this study is to analyze issues of reading habits among school students in Malaysia. This study used a qualitative method by conducting semi-structured interviews with school leaders, teachers, and parents in urban and rural areas. Sample selection used the purposive sampling method. Criteria in selecting study participants were position, teaching experience, background related to students' reading habits, and willingness to participate in this study. The findings of this study were analyzed using thematic methods. The analysis of the issues in urban areas resulted in five (5) themes for urban areas, while there were nine (9) themes for rural areas. These themes have been arranged according to the priority of the issue. The themes of issues faced in urban areas consist of (i) Students' Attitudes and Reading Awareness, (ii) Current Reading Programs Need to Be Improved, (iii) Changes in Reading Styles and Technological Developments, (iv) Aspects of Students' Environment That Do Not Support Reading Habits and (v) No Specific Time Allocation for Reading Activities. The results of the analysis of the findings of the study with participants in rural areas consist of (i) Lack of Family Support, (ii) No facilities, (iii) Students' Attitudes and Reading Awareness, (iv) Lack of Interesting Resources and Reading Materials, (v) Limited Reading Resources, (vi) Lack of Teacher Training on Reading Practice Skills, (vii) Aspects of Students' Environment That Do Not Support Reading Habits, (viii) Current Reading Program Need Improvement, (ix) No Clear Guidelines or Profile. The results of this study can serve as a reference, especially at the stakeholder level, such as for the District Education Office, School Administrators, Non-Governmental Organizations (NGOs) as well as for policymakers who may utilize the findings of this study to identify and improve the community and students in Malaysia as a reading community

Operation of Brillouin fiber laser in the O-band region as compared to that in the C-band region

A first time O band Brillouin fiber laser is demonstrated and compared with the C band Brillouin fiber laser. By utilizing a 20 km True wave fiber (TWF), the experiment demonstrated four Brillouin lines gen erated from the simple setup of Brillouin fiber laser. We compared the threshold between the Brillouin pump wavelength at 1310 nm which represent O band region and 1550 nm for C band region. It shows that the Bril louin threshold at O band region is smaller that C band. The channels spacing between these two bands are also different, where O band have 12.72 GHz spacing while 1550 nm have 10.25 GHz spacing

Fabrication and application of zirconia-erbium doped fibers

In this work, the fabrication of a Zirconia-Erbium co-Doped Fiber (Zr-EDF) and its application in the generation of non-linear effects as well as use in a compact pulsed fiber laser system is described. The Zr-EDF is fabricated by the Modified Chemical Vapor Deposition (MCVD) technique in combination with solution doping to incorporate the glass modifiers and nucleating agent. The resulting preforms are annealed and drawn into fiber strands with a 125.0 +/- 0.5 mu m diameter. Two Zr-EDFs, ZEr-A and ZEr-B, are fabricated with erbium ion concentrations of 2800 and 3888 ppm/wt and absorption rates of 14.5 and 18.3 dB/m at 980 nm respectively. Due to its higher erbium dopant concentration, a 4 m long ZEr-B is used to demonstrate the generation of the Four-Wave-Mixing (FWM) effect in the Zr-EDF. The measured FWM power levels agree well with theoretical predictions, giving a maximum FWM power - 45 dBm between 1558 nm to 1565 nm, and the generated sidebands are as predicted. The non-linear coefficient of ZEr-B is measured to be 14 W(-1)km(-1), with chromatic and slope dispersion values of 28.45 ps/nm. km and 3.63 ps/nm(2).km respectively. The ZEr-B is also used together with a graphene based saturable absorber to create a compact, passively Q-switched fiber laser. Short pulses with a pulse width of 8.8 mu s and repetition rate of 9.15 kHz are generated at a pump power of 121.8 mW, with a maximum average output power of 161.35 mu W and maximum pulse energy value of 17.64 nJ. The fabricated Zr-EDF has many potential applications in multi-wavelength generation as well as in the development of compact, pulsed laser sources. (C)2012 Optical Society of Americ

Wavelength conversion based on FWM in a HNLF by using a tunable dual-wavelength erbium doped fibre laser source

In this paper, we propose and demonstrate a cost-effective wavelength converter utilising a highly nonlinear fibre (HNLF) and a tunable dual-wavelength fibre laser as the pump source. The proposed system uses only the pump source and a signal probe to generate a partially degenerate four-wave mixing (FWM) effect. An FWM conversion efficiency of-12dB is obtained at pump and signal powers at +13.3 dBm and +5 dBm, respectively, and it is predicted that a higher conversion efficiency is possible if a high power dual-wavelength fibre laser source is used

Tunable microwave photonic frequencies generation based on stimulated Brillouin scattering operating in the L-band region

A tunable up frequencies of microwave photonics based on stimulated Brillouin scattering (SBS) for application in radio over fiber is demonstrated. The experimental setup consists of 7.7 km dispersion compensated fiber, which acts as the nonlinear medium for generating the SBS and is pumped by a narrow linewidth (0.015 nm) tunable laser operating in L-band region. The input-modulated RF at 2 GHz is upshifted to new frequencies of 7.71, 7.68, 7.65, 7.62, 7.58, and 7.56 GHz at Brillouin pump wavelengths of 1580, 1585, 1590, 1595, 1600, and 1605 nm, respectively. This system allows certain tunability in the upshifted frequencies by using a tunable laser source

Investigation of the effects of SOA locations in the linear cavity of an O-band Brillouin SOA fiber laser

An investigation into the effect of semiconductor optical amplifier (SOA) location in an O-band Brillouin SOA fiber laser (BSFL) was performed. Better output peak power flatness was generated by placing the SOA after the nonlinear medium, which is a 20 km true wave fiber (TWF) than placing it before the TWF. A maximum power of six flat output peaks with average power of - 22.0 dBm for a BP (Brillouin pump) wavelength of 1320 nm was obtained, generated from a BSFL with a SOA located after the TWF, compared with three flat Stokes signals with the SOA before the TWF at a BP wavelength of 1310 nm. The flat peak power output for the O-band Brillouin fiber laser is important, especially in producing a good O-band source