柔性阳极在城市燃气输配管线上的应用

柔性阳极早期主要是为解决覆盖层老化的老龄管道的阴极保护问题而研制开发的,目前已广泛应用于新建和已建管道及储罐的保护。本文通过在北京市天然气市内应急工程中设计、计算和应用柔性阳极阴极保护系统,提高对该技术的认识。     

不同规范对饱和砂土液化判别的差异及影响分析

现执行的规范对采用标准贯入试验判别饱和砂土液化的应用条件有不同的要求,通过分析应用条件不同,对液化评价的影响,指出若采用场地整平标高作为场地液化计算的起始标高,对实测的标贯击数尚需进行校正,而粘粒含量宜以实际粘粒含量进行液化判别标贯击数临界值的计算。     

乡村建院散落于村庄的教育

中国南方的乡村保留了过去传统生活的记忆,在接受着现代科技文明渗透的同时,等待着无限可能的到来.我们选择了较为熟悉的安徽省黄山市黟县碧山村作为思路的起点.在极具特色的徽派建筑中,碧山村未被过度商业开发,保有淳朴的民风,生活气息和历代传承下来的文化气氛浓郁.参与建筑学学习两年后,我们渴望在这儿建造一个能够真正融入村庄、开放自由的建筑学院,将传统的建筑教育回归到人人都可以参与其中的“泛建筑”状态.此次设计意在为村民和学生之间的双向沟通构筑一个平台,将建筑分散到村庄中,在对其进行合理的组织之后,既不破坏乡村肌理,又为他们之间提供更多的可能的联系.徽派建筑是长期适应地方气候的产物,当地夏季高温多雨,冬季寒冷潮湿,我们充分借鉴徽派建筑对气候与环境的回应,将其与现代技术相结合,应用到此次的设计中.如果在村庄中建一所大学会是怎样的情景?在碧山,我们一同做了一次美好的畅想.     

Enablers and barriers of the multi-user virtual environment for exploratory creativity in architectural design collaboration

Pioneering psychology and co-design research has highlighted the potential that multi-user virtual environment (MUVE) may help architects’ exploratory creativity that is a recursive search to discover an optimal match of novel and appropriate solutions. However, it has been not reported hitherto in what ways MUVE helps or obstructs architects’ exploratory creativity in individual and collaborative modes of collaboration. To investigate this issue, we compared MUVE and sketching media in face-to-face and remote collaboration modes, involving 22 pairs of architecture major students. Based on interview and video-observation, we discovered that (1) in MUVE, anthropomorphic avatars, which other media do not have, enabled individual and collaborative explorations to discover unexpected affordances of new solutions, with evaluation on physical properties and layouts of solutions. In addition, (2) co-presence with collaborator’s avatars enabled inspiration on new ways of problem-solving and puzzle-making through shared design processes and events, with co-evaluation on social aspects of design solutions. (3) Co-presence in a shared environment also allowed mutual co-exploration that promotes emerging creative solutions, with co-modification on design errors. As barriers of MUVE, (4) avatar’s immersion caused inconvenient perception to explore large-scaled environments and track collaborators’ different experiences, but the barriers were not reported in remote collaboration.     

Smart damper using sliding friction of aramid brake lining and self-centering of rubber springs

The purpose of this study is to develop a smart damper with flag-shaped behavior by using the sliding friction of aramid brake lining and the restoring capacity of pre-compressed rubber springs. For this purpose, the friction force of aramid brake lining pressed by bolts was used along with polyurethane rubbers, each with a length of 80 mm, a diameter of 95 mm, and a circular hole of 37 mm. In the experiments, loading frequency and torque force were considered. The loading frequency varied from 0.1 to 2.0 Hz, and frictional force was controlled by variable bolt torque force. The tests were conducted to demonstrate that the clamping force by the bolts could provide normal force to frictional material. The friction force by the aramid brake lining sliding was tested, followed by the pre-compressed rubber springs' behavior. Afterward, a damper combining the two components was tested to verify flag-shaped behavior by using a dynamic actuator, and the damping ratios were evaluated from the hysteretic curves. The behavior of the damper closely matched flag-shaped behavior, resulting in self-centering and energy dissipation capacity.     

环氧树脂胶黏剂涂覆木材的防水性能研究

为提高木构件的增强与防护效率,提出将粘贴增强纤维用环氧树脂(epoxy)胶黏剂兼作木构件表面防水剂的思路.选择3种木材小试样,分别涂覆1～2层Epoxy胶黏剂或醇酸清漆,进行防水性能对比试验,探讨了试样的吸水动力学特性.结果表明,Epoxy胶黏剂兼具良好的防水功能,涂覆Epoxy胶黏剂的试样其吸水率比醇酸清漆组试样低50％以上.Epoxy胶黏剂可作为高质量的木构件防水剂.     

Construction and performance analysis of a Petri net model based on a functional model in a CIM system

The so-called functional models, such as IDEF0, are useful tools for describing, designing and analysing the functional aspects of a complex manufacturing system, for example a CIM (computer integrated manufacturing) System. Though it involves considerable time and cost to build a sound functional model, the model usually cannot be used directly in further systems analysis procedures, such as quantitative performance analyses, due to its informal nature. To overcome this problem, we suggest a Petri net based procedure. First, we build a Petri net model from the IDEF0 and IDEF3 models, both of which are functional modelling tools widely used in real applications. Then, employing steady-state analysis for the Petri net, we propose a method to obtain performance measures such as the production rate. Since the analytical ability of a Petri net diminishes with increasing manufacturing system size, we develop a technique to aggregate and consolidate the Petri net to alleviate this problem that is associated with increasing complexity. An example problem is included to show the viability of our method for constructing a Petri net from a functional model and to evaluate the performance of the Petri net in an analytic manner.     

Sliding mode controller with sliding perturbation observer based on gain optimization using genetic algorithm

The Stewart platform manipulator is a closed-kinematics chain robot manipulator that is capable of providing high structural rigidity and positional accuracy. However, this is a complex and nonlinear system, so the control performance of the system is not so good. In this paper, a new robust motion control algorithm is proposed. The algorithm uses partial state feedback for a class of nonlinear systems with modeling uncertainties and external disturbances. The major contribution is the design of a robust observer for the state and the perturbation of the Stewart platform, which is combined with a variable structure controller (VSC). The combination of controller and observer provides the robust routine called sliding mode control with sliding perturbation observer (SMCSPO). The optimal gains of SMCSPO, which is determined by nominal eigenvalues, are easily obtained by genetic algorithm. The proposed fitness function that evaluates the gain optimization is to put sliding function. The control performance of the proposed algorithm is evaluated by the simulation and experiment to apply to the Stewart platform. The results showed high accuracy and good performance.