《穹顶之下》引发的生态技术价值论反思

当代科技的发展,使得有关科学技术的价值论问题得到凸显。相应的,科学技术可能对生态环境产生影响。从社会发展的角度进行探索,研究和判断,尽量的做到趋利避害,促进科学技术更好的为人类社会的健康发展服务。     

Transmittance tuning by particle chain polarization in electrowetting-driven droplets

A tiny droplet containing nano∕microparticles commonly handled in digital microfluidic lab-on-a-chip is regarded as a micro-optical component with tunable transmittance at programmable positions for the application of micro-opto-fluidic-systems. Cross-scale electric manipulations of droplets on a millimeter scale as well as suspended particles on a micrometer scale are demonstrated by electrowetting-on-dielectric (EWOD) and particle chain polarization, respectively. By applying electric fields at proper frequency ranges, EWOD and polarization can be selectively achieved in designed and fabricated parallel plate devices. At low frequencies, the applied signal generates EWOD to pump suspension droplets. The evenly dispersed particles reflect and∕or absorb the incident light to exhibit a reflective or dark droplet. When sufficiently high frequencies are used on to the nonsegmented parallel electrodes, a uniform electric field is established across the liquid to polarize the dispersed neutral particles. The induced dipole moments attract the particles each other to form particle chains and increase the transmittance of the suspension, demonstrating a transmissive or bright droplet. In addition, the reflectance of the droplet is measured at various frequencies with different amplitudes.     

Spatial selective manipulation of microbubbles by tunable surface acoustic waves

A microfluidic device based on a pair of slant-finger interdigital transducers (SFITs) is developed to achieve a selective and flexible manipulation of microbubbles (MBs) by surface acoustic waves (SAWs). The resonance frequency of SAWs generated by the SFITs depends on the location of its parallel pathway; the particles at different locations of the SAWs'' pathway can be controlled selectively by choosing the frequency of the excitation signal applied on the SFITs. By adjusting the input signal continuously, MBs can be transported along the acoustic aperture precisely. The displacement of MBs has a linear relationship with the frequency shift. The resolution of transportation is 15.19 ± 2.65 μm when the shift of input signal frequency is at a step of 10 kHz. In addition, the MBs can be controlled in a two-dimensional plane by combining variations of the frequency and the relative phase of the excitation signal applied on the SFITs simultaneously. This technology may open up the possibility of selectively and flexibly manipulating MBs using a simple one-dimensional device.     

Stabilized generation of precise triangular waves,square waves and trapezoidal waves in three phases

A new three-dimensional compact oscillator model for generating three phases of triangular waves and square waves (and also trapezoidal waves) is developed by considering carefully a recently suggested model for the precise quadrature generation of similar waves in two phases. The properties of the solution of the new model equations are investigated and they suggest that the oscillator should possess applications for the design of relatively simple electronic three phase triangular and square wave generators. “Software” applications of the model and its employment for power systems simulations are also discussed briefly.     

机辅测试给普通话语音教学带来革新力量

机器辅助普通话水平测试,关注应试人的语音标准度和发音质量,对语音教学改革提出了新的挑战。全面系统地认识语音的属性,对音素和声调进行科学分析,借助科技手段改进教学方法,提高教学质量,是语音教学改革的迫切需要。     

Historical notes on the determination of distance by timed radio waves

The foregoing notes trace the history of the measurement of the propagation times of radio waves as a means for determining distance. While the reader may feel that undue emphasis has been placed upon the KHL height measurements, a survey of the literature will show that only a small proportion of the reported observations have been cited here. Out of the hundreds of published articles on KHL height measurements, the writer has endeavored to select those which present the step-by-step improvements in the methods and apparatus. In the period just prior to the War, the United States Patents offered the principal means for tracing the development of the art. In the war period the notes are necessarily incomplete because of the scarcity of publications; this is no doubt due to secrecy conditions.     

利用心理测验对中职学生进行学习心理辅导

文章主要是从现实和理论的角度出发,通过心理测验的方法对于影响学生学习的不同的心理因素作出系统指导和训练,从而提高中职学生的心理调控能力和学习的能力,从而实现学生高效率的学习和自觉学习的能力,以达到提高学生学习成绩的近期的目标。