测定流体流速的一种简易方法

介绍了一种应用广泛操作简单的测定流体流速的简易仪器 ,并应用有关流体力学知识加以理论推导与论证。

Low Power Sensor Design for IoT and Mobile Healthcare Applications

This paper reviews recent advances in radar sensor design for low-power healthcare,indoor real-time positioning and other applications of IoT.Various radar front-end architectures and digital processing methods are proposed to improve the detection performance including detection accuracy,detection range and power consumption.While many of the reported designs were prototypes for concept verification,several integrated radar systems have been demonstrated with reliable measured results with demo systems.A performance comparison of latest radar chip designs has been provided to show their features of different architectures.With great development of IoT,short-range low-power radar sensors for healthcare and indoor positioning applications will attract more and more research interests in the near future.

Colourimetric redox-polyaniline nanoindicator for in situ vesicular trafficking of intracellular transport

Vesicular pH modulates the function of many organelles and plays a pivotal role in cell metabolism processes such as proliferation and apoptosis. Here, we introduce a simple colorimetric redox-polyaniline nanoindicator, which can detect and quantify a broader biogenic pH range with superior sensitivity compared to pre-established trafficking agents employing one-dimensional turn-on of the fluorescence resonance-energy-transfer （FRET） signal. We fabricated polyaniline- based nanoprobes, which exhibited convertible transition states according to the proton levels, as an in situ indicator of vesicular transport pH. Silica-coated Fe304-MnO heterometal nanoparticles were synthesised and utilised as a metal oxidant to polymerise the aniline monomer. Finally, silica-coated polyaniline nanoparticles with adsorbed cyanine dye fluorophores Cy3 and Cy7 （FPSNIcyB and FPSNIcy7） were fabricated as proton-sensitive nanoindicators. Owing to the selective quenching induced by the local pH variations of vesicular transport, FPSNIcy3 and FPSNIcy7 demonstrated excellent intracellular trafficking and provided sensitive optical indication of minute proton levels.

Shock control bump parametric research on supercritical airfoil

High precision of CFD code was used to study supercritical Airfoil RAE2822 superimposed with different shock control bumps under the transonic conditions.A successful improvement was made to current widely used Hicks-Henne functions which describe shock control bumps.Based on improving the airfoil's lift-drag ratio,the study shows that,(1) the best bump crest position is at the position close to 50% of bump chord,which is almost independent of free stream or pre-shock Mach numbers,but the bump height is highly coupled with the crest position,which means that the higher the bump is,the more obviously the crest position affects the airfoil lift-drag ratio,and it becomes more evident with the increase of free stream or pre-shock Mach numbers;(2) in case that the lift-drag ratio of airfoil with bump is higher than basic airfoil,almost all the optimum distances between bump crest and shock wave are close to 30% of bump chord;(3) almost all the lift-drag ratios of airfoil with bump increase as bump chord length increases,of which this trend becomes more evident as bump height increases;(4) with the increase of the bump height,almost all the lift-drag ratios of airfoil with bump decrease at low free stream or pre-shock Mach numbers.When the Mach numbers are higher,the lift-drag ratio of airfoil increases as the increase of the bump height,and particularly,the trend tends to be visible when the Mach numbers are at a high level.

Evolutionary model of the central place hierarchical system

Central place theory is one of the two theoretical cornerstones of geography, yet it cannot be connected with other spatial structure models, fails to provide definite time-space parameter conditions, lacks an evolutionary process model, and does not easily enable construction of a complete theoretical system of regional spatial structure. This paper gives an in-depth analysis of the process and mechanism for production and evolution of central places of different grades, and constructs an evolutionary model of the central place hierarchical system. The results of deduction, analysis and simulation show that production and evolution of the central place hierarchical system may be divided into five stages. These stages are the embryonic, formative, improvement, maturation, and advancement stages. Affected by spatial location and centricity, central places have obvious differences in scale and functional structures. There are great differences in the scale of same-grade central places. However, low-grade central places could have larger scales than high-grade central places, and the central places of a central location may form the agglomeration area of central places. Based on the hypothesis condition of an isotropic plain, the research shows that it is possible not only to form proportional functional structures of central places, but also to produce non-proportional scale structures of central places, and thus to complete the transformation from rationalistic deduction of spatial equilibrium mode to an explanation and demonstration of an unbalanced practical model.

Daily shoaling patterns in the zebrafish Danio rerio

Shoaling intensity in zebrafish Danio rerio is believed to vary throughout subjective day and night hours. This experiment examines long term variations in shoaling behavior. Adult zebrafish Dan io rerio were maintained under a 12：12 LD cycle （with dim red light serving as reduced visibility during subjective dark hours）, and their shoaling behavior was monitored every hour for a three-day period of time. Our results show that zebrafish perform shoaling behavior throughout subjective day and under reduced visibility conditions, although mean shoaling times during the light phase were significantly higher than mean shoaling times during the dark phase. However, on the 3^rd day of the experiment, mean shoaling times during the subjective night had increased and mean shoaling times during the subjective day had decreased. This shift in intensity was not seen on the first two days of the study, and may represent the influence of experience on the behavior of the test fish. We believe this study shows that shoaling behavior changes with light/dark cycles and that fish shoal even during reduced visibility conditions.