Supercontinuum Generation in Lithium Niobate Ridge Waveguides Fabricated by Proton Exchange and Ion Beam Enhanced Etching

We report on the fabrication of the lO-mm-long lithium niobate ridge waveguide and its supercontinuum gen- eration at near-visible wavelengths （around 800hm）. The waveguides are fabricated by a combination of MeV copper ion implantation followed by wet etching in a proton exchanged lithium niobate planar waveguide. Using a mode-locked Ti：sapphire laser with a central wavelength of 800nm, the generated broadest supereontinuum through the ridge waveguides spans 302 nm （at -30 dB points）, from 693 to 995 nm. Temporal coherence proper- ties of the supercontinuum are experimentally studied by a Michelson interferometer and the coherence length of the broadest supercontinuum is measured to be 5.2 μm. Our results offer potential for a compact and integrated supercontinuum source for applications including bio-imaging, spectroscopy and optical communication.

Enhanced heat transfer in a heat exchanger square-duct with discrete V-finned tape inserts

The article presents an experimental and numerical study on thermal performance enhancement in a constant heatfluxed square-duct inserted diagonally with 45° discrete V-finned tapes(DFT).The experiments were carried out by varying the airflow rate through the tested square duct with DFT inserts for Reynolds number from 4000 to 25000.The effect of the DFT with V-tip pointing upstream at various relative fin heights and pitches on heat transfer and pressure drop characteristics was experimentally investigated.Both the heat transfer and pressure drop were presented in terms of Nusselt number and friction factor respectively.Several V-finned tape characteristics were introduced such as fin- to duct-height ratio or blockage ratio(R_B=e/H = 0.075,0.1,0.15 and 0.2),fin pitch to duct height ratio(R_P= P/H=0.5,1.0,1.5 and 2.0) and fin attack angle,α = 45°.The experimental results reveal that the heat transfer and friction factor values with DFT inserts increase with the increment of R_B but the decrease of R_P.The inserted square-duct at R_B = 0.2 and R_P = 0.5 provides the highest heat transfer and friction factor while the one with R_B= 0.1 and R_P= 1.5 yields the highest thermal performance.Also,a numerical simulation was conducted to investigate the flow structure and heat transfer mechanism inside the tested duct with DFT inserts.

A numerical study on heat transfer enhancement and design of a heat exchanger with porous media in continuous hydrothermal flow synthesis system

The aim of this study is to use a new configuration of porous media in a heat exchanger in continuous hydrothermal flow synthesis(CHFS)system to enhance the heat transfer and minimize the required length of the heat exchanger.For this purpose,numerous numerical simulations are performed to investigate performance of the system with porous media.First,the numerical simulation for the heat exchanger in CHFS system is validated by experimental data.Then,porous media is added to the system and six different thicknesses for the porous media are examined to obtain the optimum thickness,based on the minimum required length of the heat exchanger.Finally,by changing the flow rate and inlet temperature of the product as well as the cooling water flow rate,the minimum required length of the heat exchanger with porous media for various inlet conditions is assessed.The investigations indicate that using porous media with the proper thickness in the heat exchanger increases the cooling rate of the product by almost 40% and reduces the required length of the heat exchanger by approximately 35%.The results also illustrate that the most proper thickness of the porous media is approximately equal to 90% of the product tube's thickness.Results of this study lead to design a porous heat exchanger in CHFS system for various inlet conditions.

Expanding Opening, Enhancing Economic Exchange and Cooperation

Tibet Autonomous Region lies at China’s Southwestern Plateau of Tibet and Qinghai, with broad areas, beautiful mountains and rivers, and rich resources.This old and flourishing land is an inalienable part of China’s sovereign territory, and the front-line and bridge to Southeast Asia, playing a strategic role in the political, economic and military fields.

Enhance Exchanges and Cooperation to Usher in a Bright Future of China-France Relations with Joint Efforts

Ladies and Gentlemen,Dear friends,I’m delighted to attend the roundtable discussion jointly held by the Chinese Association for International Understanding (CAFIU) and Jean Jaurès Foundation of France,and have exchanges with you in person who have been supportive

Enhance Exchanges and Cooperation and Join Hands to Create a Bright Future of China-New Zealand Relationship

From September 6 to 9,a CAFIU delegation headed by Mr.Qi Xuchun,Vice-Chairman of the National Committee of the CPPCC and Vice-President of CAFIU visited New Zealand.The following is the address made by Vice-President Qi at the University of Victoria Wellington.

Enhance International Exchange and Cooperation Jointly Promote ITS Development in China

Intelligent Transport System (ITS), a sys-tematic integration of modern hi-techs, such as computer technologies, communication technolo-gies, etc., is an important development trend in the field of communication & transportation sys-tem in the 21st century. The Chinese govern-

Building Bridges for Better Understanding between Peoples BPAFFC’s Efforts to Enhance People-toPeople Exchanges with Sri Lanka

People’s hearts are the biggest political power. People-to-people ties underpin strong and sustained connectivity, as well as international cooperation on the Belt and Road Initiative. To build bridges for greater understanding between people, the Beijing People’s Association for Friendship with Foreign Countries, together with Beijing Women’s Federation and Beijing

Quotes From China-Russia Media Forum

At the China-Russia Media Forum in St.Petersburg,Russia,on June 25,attendees touched on a variety of topics in their speeches,particularly enhancing cooperation between media organizations of the two countries and improving their abilities in international communication.Edited transcripts of selected speeches follow: