The influence of generation mix on the wind integrating capability of North China power grids: A modeling interpretation and potential solutions

The large-scale wind power development in China has reached a bottleneck of grid integrating capability. As a result, excess wind electricity has to be rejected in the nighttime low demand hours, when the wind power is ramping up. To compensate for the fluctuation of wind power, new coal-fired power plants are being constructed along with the big wind projects in the North China grids. This study analyzed why adding coal-fired generation cannot remove the bottleneck of wind integration by modeling the operating problem of the wind integration. The peak-load adjusting factor of the regional grid is defined. Building more coal-fired power plants will not increase the adjusting factor of the current grid. Although it does help to increase the total integrated wind power in the short term, it will add difficulties to the long-term wind integration. Alternatively, the coordinated resource utilization is then suggested with the discussion of both the effective pumped hydro storage and the potential electric vehicle storage.     

白蚁种间及种内群体的相容性初步研究

室内观察表明,家白蚁与肢散白蚁以及家白蚁不同种群之间缺乏相容性。它们碰在一起就格斗不止,最后造成双方重大死亡。据此提出了如何利用这种习性来达到控制白蚁危害的新思路。     

基于MapReduce和多目标蚁群算法的多租户服务定制算法

多租户服务定制能满足租户不断变化的个性化服务需求,是实现灵活的SaaS多租户软件体系结构的核心技术之一.文中给出多租户服务定制的层次结构图和定制流程,并提出基于MapReduce和多目标蚁群算法的多租户服务定制算法(MSCMA).MSCMA从众多业务流程和海量服务中为租户定制出最适合的业务流程和优化的服务组合,并设计多目标蚁群算法,应用MapReduce云计算技术,在云计算环境中分布式并行地运行优化任务,并采用优良解保持策略和解多样性保持策略.实验表明,MSCMA在求解多租户个性化服务定制问题时表现出良好的收敛性和扩展性,具有处理海量数据和大规模问题的能力.     

微型外转子无刷直流电机的仿真与分析

外转子无刷直流电机广泛应用于机车行业和航模领域,本文分析了一种航模用微型外转子无刷直流电机的基本结构,阐述了该电机的运行原理,利用Ansoft Maxwell 2D和Maxwell 3D建立了电机的二维模型和三维模型,通过有限元分析方法计算了转子不同位置时气隙磁密变化和转矩大小,验证了电机设计结构上的合理性和有效性。     

A simple way to achieve tunable adhesion in superhydrophobic nanostructured Co3O4 films

Tunable adhesive forces on the superhydrophobic nanostructured Co₃O₄ films have been achieved by simply rubbing the as-prepared films. Rubbing makes the change of morphologies of the films and leads to the tuning of adhesion. This morphology-dependent adhesive property is attributed to the difference in kinetic barriers resulting from the contact-state change. This simple and practical method can provide an important strategy for the adhesion adjustment on superhydrophobic surfaces.     

Si-based photonic quantum dots with the self-similar distributed Bragg reflectors

In this letter, optical microcavities are deposited directly on mesa-patterned substrates, and three dimensional Bragg cavities are formed due to the conformal deposition process. The room temperature photoluminescence spectra of three-dimensional Bragg microcavity exhibit a series of discrete resonant peaks. Optical field profiles of corresponding resonant peaks were given, by finite difference time domain simulation. These discrete peaks obviously show cavity resonant characteristics and optical field is mostly localized in the cavity layer. Also size dependence of cavity modes was concluded from our experimental results.     

UV laser microprocessing and post chemical etching on ultrathin Al2O3 ceramic substrate

In this study, an Nd:YVO₄ UV laser was used for microprocessing ultrathin (125 μm) ceramic plates for use as a multi-layer microchip substrate. The effects of the UV laser microprocessing parameters, including laser power density, frequency, laser scanning speed, and pass delay on microprocessing accuracy and quality (kerf width and arithmetic average roughness R_a on the kerf sidewall) were investigated by means of a 4 × 4 orthogonal design. The key processing parameters were determined and optimized for small kerf width and minimal R_a of the kerf sidewall while retaining high production efficiency. Subsequent chemical etching of the laser processed areas was performed to reduce the kerf surface and kerf sidewall roughness by removing debris and the thin recast layer for the required size precision and post gilding treatment. The results showed that a clean surface and crack-free kerf sidewall with roughness R_a of 0.16 μm could be achieved by laser microprocessing and chemical etching.     

一种基于最小二乘法的经典辩识的新方法

系统辩识方法分为经典和现代两大类.经典辩识方法采用非参数模型,其表现形式是以时间或频率为自变量的实验曲线.在对以时间或频率为自变量的实验曲线或者实验数据进行处理时,由于传统方法本身固有的缺陷,导致辩识过程的随意性较大,不能利用所有数据,从而造成不能充分利用所测数据的全部信息,不但浪费了信息,而且辩识出来的结果准确度很差.本文提出了一种用最小二乘法解决上述问题的方法,实践证明具有较高的精度,取得了较好的辩识效果.     

乙烯装置深冷泵密封改造

主要阐述了乙烯装置深冷泵密封系统的结构特点,并对原装机封失效的原因进行了分析,提出了双端面焊接金属波纹管密封结构,改造后取得了圆满的效果。