斗式提升机的结构分析及改进

分析了粮食行业斗式提升机的发展概况以及目前斗式提升机所存在的一些问题,并有针对性的提出液压自动拉紧装置和头尾轮胀套联接等优化改进措施。     

A holographic waveguide based eye tracking device

We demonstrated the feasibility of using a holographic waveguide imager for eye tracking. A holographic waveguide placed in front of the eye was used to capture images of the anterior segment of the eye and to guide the images to a camera distant from the eye. The pupil centre (PC) and corneal reflection (CR) of the eye was used to compute eye position. A custom-built model eye was used to validate the prototype eye tracker. A linear relationship between the angular eye position and the PC/CR vector was found over 60 horizontal degrees and 40 vertical degrees. The tracking accuracy and precision were 0.72 degree and 0.50 degree over these tracking ranges. These results confirmed that holographic waveguide could be a viable platform for developing compact, wearable, see-through eye trackers that can continuously monitor eye movements during real life tasks and thus can facilitate diagnosis of oculomotor disorders.     

热膨胀对塔器联合平台的影响

从理论和工程实例两方面分析了热膨胀对塔器联合平台中的直梯、斜梯和过道的影响，并提出了较为合理的设计方案。     

东北350MW供热机组循泵选型优化分析

针对东北地区350 MW供热机组湿冷系统循环水泵选型情况,结合华能大庆2×350 MW热电联产项目对寒冷地区供热机组循环水泵进行选型,结果表明,单级双吸卧式离心泵投资少、检修方便、运行可靠、运行成本低。     

Design and analysis of implantable CPW fed bowtie antenna for ISM band applications

A novel implantable coplanar waveguide (CPW) fed crossed bowtie antenna is proposed for short-range biomedical applications. The antenna is designed to resonate at 2.45 GHz, one of the industrial-scientific-medical (ISM) bands. It is investigated by use of the method of moments design equations and its simulation software (IE3D version 15). The size of the antenna is 371.8 mm³ (26 mm × 22 mm × 0.65 mm). The simulated and analyzed return losses are −23 and −25 dB at the resonant frequency of 2.45 GHz. We have analyzed some more performances of the proposed antenna and the results show that the proposed antenna is a perfect candidate for implantation. The proposed antenna has substantial merits like low profile, miniaturization, lower return loss and better impedance matching with high gain over other implanted antennas.     

Flame morphology and self-acceleration of syngas spherically expanding flames

The self-acceleration of spherically expanding flames were investigated using a constant volume combustion chamber for CO/H₂/O₂/N₂ mixtures over a wide range of initial pressure from 0.2 to 0.6 MPa, CO/H₂ ratio from 50/50 to 10/90 and equivalence ratio from 0.4 to 1.5. The adiabatic flame temperature was kept constant by adjusting O₂/N₂ ratio at different equivalence ratios. Schlieren images were recorded to investigate the flame front evolution of spherically expanding flames. Local acceleration exponents were extracted using a proper equation to study the process of flame self-acceleration. Results show that the flame cells develop on the smooth flame fronts and finally reach fractal-like structures due to the hydrodynamic and diffusional-thermal instabilities, resulting in flame self-accelerative propagation. The critical Peclet number corresponding to the onset of self-acceleration, Pe_cr increases nonlinearly with the Markstein length, Ma. The observation further reveals that the onset of self-acceleration is mainly controlled by the diffusional-thermal effect. There exists two distinct flame propagation regimes in the self-acceleration, namely quick transition accelerative and quasi self-similar accelerative regimes. The quick transition regime is controlled by the destabilization effect of hydrodynamic perturbation and stabilization effect of flame stretch. While the quasi self-similar regime is primarily affected by the cascading process of flame front cells controlled by hydrodynamic instability. The self-similar acceleration exponent, α_s varies with the initial pressure and Lewis number, Le. The values of α_s are measured to be 1.1–1.25 (smaller than 1.5), indicating the flame dose not attain self-turbulization.     

浅谈如何做好电力业扩报装工作

随着我国社会经济和科学技术的迅速发展，电力业扩报装工作取得了明显的进步。但是，在业扩报装工作中依然存在许多问题，例如业扩报装的工作时间长、收费的公开度低、工作环节多等，这些问题不仅成为电力用户关注的焦点，对电力企业的售电量也产生了重要的影响。     

Scattering of guided shear waves in plates with discontinuities

This paper investigates the interaction of the SH0 mode with discontinuities in plate waveguides. The scattered fields are evaluated using a novel method that exploits the principle of reciprocity in elastodynamics. The results obtained compare to those provided by a finite element model. Very good agreement between the analytical and numerical models proves the effectiveness of the proposed approach, enabling us to clearly elucidate the role of the different size and shape parameters involved. The discontinuities considered are single and double sharp reductions of plate height of different amounts and lengths, where both symmetric and nonsymmetric one-sided notch cases are treated. Regimes related to low and high values of the product frequency and height of the plate are investigated, showing the dependence of reflection and transmission coefficients on length and height of the discontinuity, as well as the occurrence of mode conversion. The analytical approach proposed leads to a better understanding of the interaction of guided waves with discontinuities, which may stimulate the application of guided waves to defect sizing rather than to simple detection.     

To reduce side lobe level of slotted array antennas using nonuniform waveguides

In this article, a method is presented to reduce the side lobe level of slotted waveguide array antennas while the gain to be constant. In this method, the H‐plane dimension of the waveguide is considered as the variable rather than constant. The nonuniformity of waveguide walls obviates the need for offset of slots and thereby reduces the side lobe level of radiation pattern. A slotted nonuniform waveguide is designed at frequency 10 GHz and then fabricated and tested. © 2015 The Authors International Journal of RF and Microwave Computer‐Aided Engineering Published by Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:42–46, 2016.     

Alkaline aluminum phosphate glasses for thermal ion-exchanged optical waveguide

Alkaline aluminum phosphate glasses (NMAP) with excellent chemical durability for thermal ion-exchanged optical waveguide have been designed and investigated. The transition temperature Tg (470 °C) is higher than the ion-exchange temperature (390 °C), which is favorable to sustain the stability of the glass structure for planar waveguide fabrication. The effective diffusion coefficient D_e of K⁺–Na⁺ ion exchange in NMAP glasses is 0.110 μm²/min, indicating that ion exchange can be achieved efficiently in the optical glasses. Single-mode channel waveguide has been fabricated on Er³⁺/Yb³⁺ doped NMAP glass substrate by standard micro-fabrication and K⁺–Na⁺ ion exchange. The mode field diameter is 9.6 μm in the horizontal direction and 6.0 μm in the vertical direction, respectively, indicating an excellent overlap with a standard single-mode fiber. Judd–Ofelt intensity parameter Ω₂ is 5.47 × 10⁻²⁰ cm², implying a strong asymmetrical and covalent environment around Er³⁺ in the optical glasses. The full width at half maximum and maximum stimulated emission cross section of the ⁴I_13/2 → ⁴I_15/2 are 30 nm and 6.80 × 10⁻²¹ cm², respectively, demonstrating that the phosphate glasses are potential glass candidates in developing compact optoelectronic devices. Pr³⁺, Tm³⁺ and Ho³⁺ doped NMAP glasses are promising candidates to fabricate waveguide amplifiers and lasers operating at special telecommunication windows.