Controlling the light wavefront through a scattering medium based on direct digital frequency synthesis technology

Phase modulation is a crucial step when the frequency-based wavefront optimization technique is exploited to measure the optical transmission matrix(TM) of a scattering medium. We report a simple but powerful method, direct digital frequency synthesis(DDS) technology to modulate the phase front of the laser and measure the TM. By judiciously modulating the phase front of a He–Ne laser beam, we experimentally generate a high quality focus at any targeted location through a 2 mm thick 120 grit ground glass diffuser, which is commercially used in laser display and laser holographic display for improving brightness uniformity and reducing speckle. The signal to noise ratio(SNR) of the clear round focus is 50 and the size is about 44 μm. Our study will open up new avenues for enhancing light energy delivery to the optical engine in laser TV to lower the power consumption, phase compensation to reduce the speckle noise, and controlling the lasing threshold in random lasers.

DICP Symposium (I) on Catalysis: Future Directions of Catalysis Science and Technology October 16-18, 2003, Dalian, China

Introduction and Invitation DICP Symposium is a special series of interna-tional conference named after the Dalian Instituteof Chemical Physics (DICP). The DICP Symposiumwas founded with the purpose to promote the interna-tional communication and collaboration between theDICP and the international scientific community, to

Current Situation and Trend of the Technology Development of China’s Oral Care Products

This paper details the latest situation and features of the technology development in terms of China’s oral care products industry and proposes the following development direction in this sector. Meanwhile, the paper analyzes the popular products in the international market of oral care products and also predicts the trend of the product future in China’s market.

Evolution and application of in-seam drilling for gas drainage

The presence of seam gas in the form of methane or carbon dioxide presents a hazard to underground coal mining operations.In-seam drilling has been undertaken for the past three decades for gas drainage to reduce the risk of gas outburst and lower the concentrations of seam gas in the underground ventilation.The drilling practices have reflected the standards of the times and have evolved with the development of technology and equipment and the needs to provide a safe mining environment underground.Early practice was to adapt equipment from other felds,with rotary drilling being the only form of drilling available.This form of drainage allowed various levels of gas drainage coverage but with changing emphasis,research and development within the coal industry has created specifc equipment,technology and practices to accurately place in-seam boreholes to provide effcient and effective gas drainage.Research into gas content determination established a standard for the process and safe levels for mining operations to continue.Surveying technology improved from the wire-line,single-shot Eastman survey instruments which was time-dependent on borehole depth to electronic instruments located in the drill string which transmitted accurate survey data to the drilling crew without time delays.This allowed improved directional control and increased drilling rates.Directional drilling technology has now been established as the industry standard to provide effective gas drainage drilling.Exploration was identifed as an additional beneft with directional drilling as it has the ability to provide exploration data from long boreholes.The ability of the technology to provide safe and reliable means to investigate the need for inrush protection and water drainage ahead of mining has been established.Directional drilling technology has now been introduced to the Chinese coal industry for gas drainage through a practice of auditing,design,supply,training and ongoing support.Experienced drilling crews can offer site specifc gas drainage drilling services utilising the latest equipment and technology.

The First China Foundry Scientific and Technological Achievements Fair was successfully held in Changsha

In order to promote transformation of scientific and technological achievements and development of scientific and technological service in foundry industry,change innovative achievements into real industrial activities and market profit,and create new growth sources,under the leadership of the Ministry of Science and Technology, the Productivity Promotion Center of Foundry Industry of China maximized resource advantages, fully integrated innovative resources, took market demands as guidance, built interconnected service platforms, supplied ＂one-stop＂ services for scientific and technological innovation in the foundry industry and the development of small and medium-sized enterprises.

Key technologies of the emergency platform in China

An emergency platform is an informatization support platform for disaster information perception,disaster situa-tional awareness,and emergency decision command.This is a key tool for ensuring the efficiency and effectiveness of emergency responses.Numerous large countries have conducted in-depth research on the key technologies of emergency platforms.Over the past 20 years,with the reform of emergency management mechanisms,China has developed two generations of emergency platform systems.This paper reviews the two generations of emergency platforms and summarizes their key technologies including multi-source-based monitoring and early warning,multi-hazard risk assessment,“scenario-response”-based decision support,synthetical forecasting based on in-cident chain,and emergency common operational picture(COP)for command and dispatch.Future research directions for the next generation emergency platforms are also proposed.