用于多显示屏背光照明的多用途白光LED驱动器

引言 今年,预计全球将生产超过6亿部蜂窝电话.这些蜂窝电话不仅是人们的通话工具,现今最新型的蜂窝电话还可用来浏览Web、无线传输电子邮件、拍照甚至收看流式视频.消费者对这些"丰富功能"的需求给电话制造商们带来了越来越大的压力,它们必须把这些功能放进越来越小的电话中,同时还要保证电池的使用时间.     

Probing young drinking water biofilms with hard and soft particles

The aim of our study was to investigate, through the use of soft (Escherichia coli) and hard (polystyrene microspheres) particles, the distribution and persistence of allochthonous particles inoculated in drinking water flow chambers. Biofilms were allowed to grow for 7-10 months in tap water from Nancy's drinking water network and were composed of bacterial aggregates and filamentous fungi. Both model particles adhered almost exclusively on the biofilms (i.e. on the bacterial aggregates and on the filamentous structures) and not directly on the uncolonized walls (glass or Plexiglas). Biofilm age (i.e. bacterial density and biofilm properties) and convective-diffusion were found to govern particle accumulation: older biofilms and higher wall shear rates both increased the velocity and the amount of particle deposition on the biofilm. Persistence of the polystyrene particles was measured over a two-month period after inoculation. Accumulation amounts were found to be very different between hard and soft particles as only 0.03‰ of the soft particles inoculated accumulated in the biofilm against 0.3-0.8% for hard particles.     

Effects of delayed drying and CO2 application on copper amine fixation in ACQ treated red pine

Fixation of copper and amine in alkaline copper quaternary (ACQ-C) wood preservative was investigated to determine the effects of delayed drying and application of CO₂ gas under pressure. Unlike the fixation of CCA preservative, where the rate of fixation reaction is slowed down by evaporative cooling during drying, delayed drying of ACQ treated wood had no observable effect on the copper fixation rate. However, at 50 °C, delayed drying resulted in a higher degree of copper fixation, while this effect was not observed at 22 °C. Post-treatment of ACQ treated wood with pressurized CO₂ immediately after treatment, reduced the pH of the solution in wood and resulted in rapid fixation of the copper. However, in time, the pH increased as CO₂ dissipated from the solution allowing the copper to re-solubilize.     

Effect of hot air post-treatments on copper leaching resistance in ACQ-D treated Chinese fir

Chinese fir (Cunninghamia lanceolata Hook.) wood cubes (19?×?19?×?19 mm³) were treated with amine copper quat-type D (ACQ-D) solution and fixed with different hot air post-treatments. The effects of temperature, relative humidity, duration, air circulation of post-treatment as well as the copper retention in the treated wood on copper leaching were investigated. With the help of ultraviolet or visible spectroscopy (UV/VIS), the valence conversion of copper in treated wood post-treated with optimal post-treatment conditions was investigated, and its relation with copper leaching was also discussed. The results showed that besides temperature and relative humidity, air circulation during hot air post-treatments also had a significant effect on accelerating copper fixation in ACQ-D treated wood. 70 °C, 80% R.H. with good air circulation provided a suitable condition for complete fixation of copper in a short period. After the applied post-treatments, up to 11.3% cupric copper reduced to cuprous form. A higher copper conversion rate usually corresponds to lower copper leaching, which is consistent with the contribution of lower water solubility cuprous copper.     

Governing GMOs in the USA: science,law and public health

Controversy surrounds the production and consumption of genetically modified organisms (GMOs). Proponents argue that GMO food sources represent the only viable solution to food shortages in an ever‐growing global population. Science reports no harm from GMO use and consumption so far. Opponents fear the potentially negative impact that GMO development and use could have on the environment and consumers, and are concerned about the lack of data on the long‐term effects of GMO use. We discuss the development of GMO food sources, the history of legislation and policy for the labeling requirements of GMO food products, and the health, environmental, and legal rationale for and against GMO food labeling. The Food and Drug Administration regulates food with GMOs within a coordinated framework of federal agencies. Despite mounting scientific evidence that GMO foods are substantially equivalent to traditionally bred food sources, debate remains over the appropriateness of GMO food labeling. In fact, food manufacturers have mounted a First Amendment challenge against Vermont's passage of a law that requires GMO labeling. Mandatory GMO labeling is not supported by science. Compulsory GMO labels may not only hinder the development of agricultural biotechnology, but may also exacerbate the misconception that GMOs endanger people's health. © 2015 Society of Chemical Industry     

Center of mass approximation and prediction as a function of body acceleration

In order to maintain postural stability, the central nervous system must maintain equilibrium of the total center of body mass (COM) in relation to its base of support. Thus, the trajectory of the COM provides an important measure of postural stability. Three different models were developed to estimate the COM and the results tested on 16 subjects: namely a neural network, an adaptive fuzzy interface system and a hybrid genetic algorithm sum-of-sines model. The inputs to the models were acquired via two accelerometers, one representing the trunk segment placed on T2 and the second representing the limb segment placed on the shank below the knee joint. The portability, ease of use and low cost (compared with video motion analysis systems) of the accelerometers increases the range of clinics to which the system will be available. The subjects performed a multisegmental movement task on fixed and foam surfaces, thus covering a relatively wide dynamic scope. The results are encouraging for obtaining COM estimates that have clinical applications; the genetic sum-of-sines model was found to be superior when compared to the other two models.     

Surface roughness of stainless-steel mirrors for focusing soft x rays

We have used polished stainless steel as a mirror substrate to provide focusing of soft x rays in grazing-incidence reflection. The critical issue of the quality of the steel surface, polished and coated with gold, is discussed in detail. A comparison is made to a polished, gold-coated, electroless nickel surface, which provides a smoother finish. We used the surface height distributions, measured with an interferometric microscope and complemented by atomic-force microscope measurements, to compute power spectral densities and then to evaluate the surface roughness. The effects of roughness in reducing the specular reflectivity were verified by soft-x-ray measurements.     

一种利用暂态响应分析提高电磁层析成像测量信号信噪比的新方法

本文提出了一种提高电磁层析成像测量信号信噪比的新方法。在电磁层析成像的前端测量电路中,最重要的一环是一个含有低通滤波器的相敏解调电路,当激励源从一个线圈切换到另一个线圈时,接收电压值发生变化,从而引起一个暂态响应过程。通常,测量和数模转换要等暂态响应过程完成、电压信号稳定后进行。本文提出了一种利用分析暂态相应过程中所含的信息而提高电磁层析成像测量信号信噪比的新方法。仿真和实验结果肯定了这种方法的有效性,测量到的电感值的标准方差下降多于50%。     

今天的绿色POL DC/DC转换器设计需要高效率和低IQ

大多数嵌入式系统都是由48V背板供电的.这个电压通常要降至较低的24V、12V或5V的中间总线电压,以向系统内的电路板支架供电.