Engineering geological properties of Miocene hard clays along the middle line of the North–South Diversion Water Project in China

Miocene hard clays are widely distributed in eastern China and are associated with extensive damage to engineering structures. This paper presents the engineering geological properties of Miocene hard clays along the middle line of the North–South Diversion Water Project (NSDWP), including areas of the Nanyang Basin as well as the Fangcheng-Baofeng and Handan-Yongnian regions. Results of laboratory testing show that beneath the weathering zone the Miocene hard clays have similar engineering geological properties, including a high clay fraction with significant montmorillonite, high physico-chemical activity, high water content and high to very high shrink/swell. The effects of wetting and drying cycles on the swelling potential of the hard clays are summarized and attention drawn to the importance of these when considering excavation and construction.

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Computer-Integrated System for Estimating the Costs of Building Projects

The cost estimate is considered one of the most important and critical phases of a construction project. Preparing reliable and accurate estimates to help decision makers is the most challenging assignment that cost engineers and estimators face. For decades, practitioners in the construction industry focused only on estimating the initial cost of a facility, neglecting costs associated with operating and maintaining it. Today, more interest lies in investigating the economics of facility management, which include the cost of owning and operating a building over its useful life. This paper presents a methodology that can be used for an integrated conceptual cost estimating and life-cycle cost analysis for construction projects during their initial phase. The methodology describes the development and implementation of a system that automates the preparation of parametric cost estimates and forecasts future running costs of building projects. The system integrates relational databases, a parametric cost estimate module, an AutoCAD module, a global module, a cost estimate forecasting and decision support system module, and a life cycle costing and sensitivity analysis module. The system will automatically generate a new parametric estimate upon any modification in building design. Once the capital costs are identified, the system forecasts the cost of running and maintaining the new building throughout its expected service life. After assigning the range of deviation, a sensitivity analysis is conducted, which identifies the most sensitive parameters for further consideration and analysis. Designing the system in a user-friendly environment allows owners and decision makers to envision the feasibility of new building projects within their anticipated life cycles. Moreover, it assists architects and cost engineers in generating parametric cost estimates in a dynamic environment. A numerical case example is presented to illustrate the usefulness and capabilities of the developed system.     

Structural modifications of Callovo-Oxfordian argillite under hydration/dehydration conditions

The clay minerals are among the first silicated minerals to be transformed physically and chemically during changes of temperature, pressure, relative humidity and fluid composition. One of the first physical processes, extremely rapid, is the hydration and/or dehydration of swelling clays minerals. These processes could generate changes of the clay structure and consequently the texture of an argillaceous rock. In order to observe in situ structural modifications on a deep argillaceous rock “argillite” (Parisian basin, in France) according hydration–dehydration cycles, an Environmental Scanning Electron Microscope (ESEM) was used. This instrument allows the possibility to observe geological samples in their natural state without preliminary preparation or modification. Two types of samples were prepared, parallel and perpendicular to the lithology. Then, each sample was submitted to three water condensation/evaporation cycles.The observed samples were from the Callovo-Oxfordian formations in HTM 80743, HTM 983, HTM 02618 and EST 2159 cores. ESEM observations show that the water sensitivity of these bulk samples depends directly on the clay mineral proportion in the rock, and on the clay family present. It is also obvious that the water sensitivity depends on the anisotropy of the pore structure and the particle size and total porosity. The main structural modifications observed were the cracking of the surface, particles aggregation/disaggregating and opening/closing of pores and/or cracks.     

压电比例式阀门定位器的控制方法研究

压电式阀门定位器以其低耗气量以及低耗电量,被广泛应用于气动调节阀中.分析比例式压电阀的特性,在一定电压范围内,其进气口和排气口随着控制电压的不同而呈现出不同的开口大小.针对阀的这种特性,并考虑到气动执行机构的非线性,提出了一种控制算法,并且给出控制过程中所需参数的整定步骤与方法.利用dSPACE系统作为开发平台,并配合...     

电网仿真培训系统图形支撑平台的研究

介绍了通用电网仿真培训系统 (DTS)图形支撑平台的主要内容 ,包括图形编辑模块、教员 /学员机图形显示系统、图形的打印等 ,确定了设计原则 ,充分考虑了平台的开放性、扩展性和模块化 ,并以河南 DTS为实例实现了所提出的设计思想     

Performance of Al2O3 particle reinforced glass-based seals in planar solid oxide fuel cells

Glass-based materials are usually considered as excellent seals for jointing adjacent components in planar solid oxide fuel cells, but the uncontrollable crystallization in the glass may cause delamination and micro-cracks in such seals. To solve this problem, Al2O3 ceramic particles were added to a BaO–CaO–Al2O3–B2O3–SiO2 glass system to reduce negative effects caused by crystalline phase on the gas tightness and the joint strength in the seals. At an operating temperature of 750 °C, the glass-based seals with 20 wt% Al2O3 addition (GA80) exhibited extremely low leakage rates (~0.002 sccm/cm under an input gas pressure of 13.6 kPa) and higher shear strength (3.31 MPa). The Al2O3 ceramic addition and the crystalline phase BaAl2Si2O8 reinforced the glass matrix. Further thermal cycle analyses indicated that leakage rates for the GA80 seals remained at around 0.0025 sccm/cm after 10 thermal cycles, which was consistent with minor microstructural change and good interface bonding. Single cell testing with of GA80 seals was performed and the results demonstrated stable electrochemical performance through 6 thermal cycles at an open circuit voltage of 1.16–1.18 V, as well as a power density above 546 mW/cm2 at a current density of 925 mA/cm2. These results showed the high thermal cycle stability of the glass/Al2O3 composite seals in intermediate temperature planar solid oxide fuel cells.     

氨基改性蠕虫型介孔SiO_2吸附CO_2性能的研究

采用D2000为模板剂,TEOS为硅源,在中性的条件下合成了具有较大孔径的蠕虫型介孔SiO2(MSU-J),并采用四乙烯五胺(TEPA)通过物理浸渍的方法制备不同质量分数的TEPA改性的MSU-J,得到具有高吸附量的CO2吸附剂。利用FT-IR,N2吸附/脱附及TG对所制备的样品进行表征。CO2的吸附试验是在不同氨基质量分数(20%,30%,50%,70%)以及不同温度下测试。吸附实验表明,浸渍TEPA后,吸附剂由单纯的物理吸附转变为以氨基为活性中心的化学吸附,且随着TEPA浸渍含量的增加吸附量先增加后降低,当TEPA负载量(质量分数)为50%时,吸附量可达到164.3 mg/g。温度对吸附剂的吸附性能也有一定的影响,最佳的吸附温度为25℃,这与吸附机理有关,随着温度的升高,反应向解吸附方向移动。循环性试验表明,所制备的吸附剂具有良好的循环性能,材料重复使用6次,对CO2吸附性能只有少量的下降,这可能是由于TEPA的挥发或者部分分解引起的。     

Realizing n-type BiCuSeO through halogens doping

Since the p-type BiCuSeO has been well developed in 2010, the maximum ZT value > 1.5 was achieved. Recently, the extensive research on n-type BiCuSeO is of interest to match its p-type counterpart. In this work, we found that n-type BiCuSeO can be successfully obtained in Bi_1.04Cu_1.05Se_0.99X_0.01O by using halogens (X = Cl, Br, I) doping. The first-principle calculations on the electronic band structure of BiCuSeO show that the Fermi levels were shifted into the conduction band by halogens doping at Se site. Both electrical transport properties and Hall measurements indicate that halogens are effective electron-dopants to realize n-type BiCuSeO. Interestingly, the results of temperature-dependent Seebeck coefficients elucidate a p-n-p type transport behavior, which experience less and less pronounced with increasing heating-cooling measurement cycles until n-type transports disappeared. Our results indicate that even though a large negative Seebeck coefficient (– 500 μV/K) can be realized in n-type BiCuSeO, but these n-type behaviors are reversible and unstable due to the fragile bonding in Cu-X (X = Cl, Br, I), and thus halogens losing upon several measurement cycles for heating and cooling. Even though our results indicate that the obtained n-type BiCuSeO is not stable through halogens doping, the calculated projected density of states elucidate that a high-performance n-type BiCuSeO can be expected by electron-doping at Bi sites.     

内燃机火焰平均传播时间的测量电路设计

本文论述了内燃机N个连续循环中火焰平均传播时间的测量原理,设计了相应的测量电路,讨论了提高测量精度的方法,因而给内燃机动态测试提供了一种新的有效方法,同时亦给其它各种机构时间特性的分析测量提供了一种新的简单方法。