连续采煤机截割参数的确定及计算

通过系统地阐述连续采煤机的截割参数的意义和它们之间的相互关系,利用类比和试验的手段总结出了截割部主要参数的计算方法,为连续采煤机截割部参数的计算提供了完整的思路。为装运、行走、整机的设计、计算提供了有益的参考。     

邯郸路地道大体积混凝土浇筑的质量控制

上海市邯郸路地道为长距离浅埋式地道,全长1 285 m。深基坑开挖、支撑和大方量混凝土浇捣的质量控制是工程施工的技术重点和难点。从施工前准备及技术交底、施工温度应力控制和裂缝控制等3个方面,详细介绍了底板大梁浇筑工艺、浇筑层厚度控制、振捣的时间点等重点交底内容;在施工中采取掺和粉煤灰及微型膨胀剂(UEA)等措施,控制施工温度应力;强调了冬季防止大体积混凝土裂缝所采用的4种措施。     

新疆深厚覆盖层坝基防渗处理技术

随着建坝条件的复杂化，在覆盖层上建坝逐渐成为了一发展趋势。本文简要介绍了新疆深厚 覆盖层地基上不同土石坝的建坝经验，分析了深厚覆盖层上建坝的一些技术问题及相应的处理措施。     

Conduction mechanism in antiferrolectric PbZrO3 thin films—analysis of charge carrier trapping phenomenon

Abstract

Antiferroelectric compositions, such as PbZrO₃, are attractive candidates in charge storage devices and actuator/transducer applications in MEMs technology. Thin films of PbZrO₃were deposited on Pt coated Si substrates by a pulsed excimer ablation process. The process of field induced ferroelectric phase switching involves the domain wall reorientation in the polycrystalline thin films. The presence of grain boundaries and various defects in the polycrystalline thin films acts as the pinning sources for the various domain walls. These defects capture the charge carriers in the presence of external applied field and hinders further switching of the dipoles in the domains, thereby increases the response times and threshold voltages for the devices operations. Understanding of the trapping phenomenon in these films is very essential. Using Lampert's theory of space charge limited conduction both shallow and deep trap energies were estimated approximately from charge transport analysis.     

深水锚泊线串联浮筒系统的动力特性分析

在时域范围内建立深水锚泊线串联浮筒系统的动力分析模型,考虑锚泊线和海床之间的接触作用,基于Morison公式计算锚泊线的惯性力和拖曳力荷载,并利用单根锚泊线由于上部浮体运动而吸收的能量来计算锚泊阻尼。分析串联浮筒系统对锚泊线张力和阻尼的影响特征,进而对串联浮筒的大小和所处位置进行参数敏感性分析。该结果对深水浮式平台锚泊系统设计中如何有效地减小锚泊张力具有实际意义。     

Large scale cathodic exfoliation of graphite using deep eutectic solvent and water mixture

A short-time and low-cost synthesis route was used to produce large lateral size (from 2 to 15 μm) from monolayers to few layers of graphene by a two-step process of electrochemical exfoliation with a deep eutectic solvent in a mixture with water that can be reused, and ultrasonic bath. The graphene was characterized by SEM, TEM, AFM, Raman and electrochemical activity. During the electrochemical exfoliation, high expanded graphene particles were obtained and these were dispersed in a mixture of water with 5%wt ethylene glycol by an ultrasonic bath in order to complete the exfoliation process. An enhancement of the electrical conductivity of these dispersions was obtained with the increase of graphene concentration, 0.38 mg/mL, which best result was achieved with 30 wt% water and a DC voltage of 10 V. It was possible to add a conductive layer to a glass substrate with the graphene obtained and Tyndall effect was observed.     

Differences in lithospheric structures between two sides of Taihang Mountain obtained from the Zhucheng-Yichuan deep seismic sounding profile

A 2-D model of lithospheric velocity structures in the southern part of the North China Craton was obtained using data from the Zhucheng-Yichuan deep seismic sounding profile.Results show that there are great differences in lithospheric structures between two sides of Taihang Mountain.In the eastern region,the lithosphere is thinner,with a thickness of about 70-80 km,while in the western region,the thickness is 85-120 km.There is a jump of the lithospheric thickness across Taihang Mountain gravity anomaly b...     

DDC在建筑电气设计中的应用研究

探讨DDC在建筑电气设计中的应用,以DDC为核心设计变风量空调末端(VAV BOX)控制器,介绍控制算法设计,工程实验运行和数据分析证明能够满足现场运行要求。     

Corrosion–erosion wear of N80 carbon steel and 316L stainless steel in saline–quartz slurry

The corrosion–erosion behavior of carbon steel N80 and austenitic stainless 316L are investigated both in water–quartz slurry and saline–quartz slurry. The sample mass losses after each test and the roughness of sample surfaces are measured and a potentiostat is used to gain the polarization curves. The worn surfaces and the corrosion–erosion wear mechanism are analyzed using scanning electron microscopy (SEM) and 3D ultra‐deep microscopy. Results show that the R_a for N80 is much larger than 316L under the same experimental condition, and the weight losses of the two materials show a similar trend except for tests with higher impact angles. The lowest R_sm for 316L matches along with the highest R_sm for N80 at the 45 min testing time. According to the obtained results of the corrosion–erosion mechanism of the N80 and 316L based on the SEM and 3D ultra‐deep microscopy, the conclusion is drawn that the ploughing and crashing are the major mechanisms for the forming of surface morphologies and the mass removal. Different impact angles and materials affect the corrosion–erosion process to some extent.     

季节性冻土深基坑支护技术研究

通过对中国地质大学(北京)综合游泳馆工程拟建场地土层的土质、深度及基坑深度的分析与比较,确定出基坑深度范围内土层的土质。介绍了季节性冻土深基坑支护经常出现的问题,并分析了这些问题出现的原因。对常用土钉支护方法在季节性冻土深基坑支护中运用的局限性做了总结,最后提出一种改进的土钉支护方法。该法针对冻土发生冻融循环时冻胀与融沉的特点采取了相应的控制措施,从而保证了季节性冻土深基坑的稳定性。该法操作简单可行,实践证明效果明显。