Feature technology and its applications in computer integrated manufacturing

A Thesis submitted for the degree of Doctor of Philosophy of University of LutonComputer aided design and manufacturing (CAD/CAM) has been a focal research area for the manufacturing industry. Genuine CAD/CAM integration is necessary to make products of higher quality with lower cost and shorter lead times. Although CAD and CAM have been extensively used in industry, effective CAD/CAM integration has not been implemented. The major obstacles of CAD/CAM integration are the representation of design and process knowledge and the adaptive ability of computer aided process planning (CAPP). This research is aimed to develop a feature-based CAD/CAM integration methodology. Artificial intelligent techniques such as neural networks, heuristic algorithms, genetic algorithms and fuzzy logics are used to tackle problems. The activities considered include: 1) Component design based on a number of standard feature classes with validity check. A feature classification for machining application is defined adopting ISO 10303-STEP AP224 from a multi-viewpoint of design and manufacture. 2) Search of interacting features and identification of features relationships. A heuristic algorithm has been proposed in order to resolve interacting features. The algorithm analyses the interacting entity between each feature pair, making the process simpler and more efficient. 3) Recognition of new features formed by interacting features. A novel neural network-based technique for feature recognition has been designed, which solves the problems of ambiguity and overlaps. 4) Production of a feature based model for the component. 5) Generation of a suitable process plan covering selection of machining operations, grouping of machining operations and process sequencing. A hybrid feature-based CAPP has been developed using neural network, genetic algorithm and fuzzy evaluating techniques

A Tentative Approach to Mapping Street Space: A Case Study of Chinese Central Urban Districts

This paper focuses on exploring a quantitative approach to mapping street space. Characteristics of street space can hardly be described and explained using only the traditional architectural forms of street space. The difficulty arises because of the lack of relevance between these forms and people’s activities in them.This phenomenon presents a challenge to mapping methods. Expanding mapping elements is one viable and ongoing path. Which element could be an effective one and how it should be measured and mapped, are vital questions. Interface signs have been selected as the experimental elements, with an area of central Nanjing selected as the research sample.Database and statistics of interface signs and pedestrian flows have been established and inserted into the GIS (Geographical Information System) where a series of correlation analyses between basic mappings and pedestrian flows are carried out

Evaluation of Generating Mechanism of Residential Building Patterns in Contemporary Cities – Case Study on Xi’an and Nanjing

[EN] Residential area occupies a large portion of urban land, so it is very important to understand the characteristics of the residential building patterns and how such patterns, normally parallel multi-story and high-rise slab apartments in various cities of China, are formed. The residential building patterns are according to the living behavior, climate consideration, environmental requirement and market demands. Our previous studies have shown that sunshine regulation is by far the most important factor in the generation of the residential building pattern since 1980. This paper attempts to make a comprehensive evaluation to see the generating mechanism of the residential morphological patterns. Ten residential plots from two cities located in different climate zones of Xi’an and Nanjing are evaluated. Five factors, namely, the type of the apartment, plot FAR, land coverage, sunshine regulations and spatial characteristics of plot pattern, will be used as comprehensive evaluation indicators in the comparison. The study reveals how these factors interplay in the generation of the observed plot patterns and which factor is most important in this process. If the sunshine regulations were the key factor, how different the plot patterns in different climate zones and latitudes would have varied. Through evaluating generating mechanism we could find out the key generating factors, which is useful as the references for design.This study was financially supported by National Natural Science Foundation of China (No.51538005).Li, R.; Tang, L.; Ding, W. (2018). Evaluation of Generating Mechanism of Residential Building Patterns in Contemporary Cities – Case Study on Xi’an and Nanjing. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 331-341. https://doi.org/10.4995/ISUF2017.2017.5920OCS33134

Identify Urban Spatial Patterns Based on the Plot Shapes and Building Setting in Downtown of Nanjing

[EN] he geometric characteristics of modern cities have been difficult to describe that is important for urban design, which deserve to be further interpreted. Taking advantage of Conzen’s methodology, the building is tightly related with its plot, which means the certain building pattern can be described by examining the generation of the building arrangement within the plot. Simultaneously, the building pattern is highly affected by the plot pattern it is located. In view of these, plot patterns together with land property and site coding could be taken as the clue for understanding both building patterns and urban spatial configuration. 35 commercial blocks in Nanjing downtown areas are chosen as research samples. Firstly, the internal structure of the blocks will be studied by analyzing the patterns, functions and land utilities of its plots. Focusing on the site coding and regulation, the building arrangement could be clarified and mapped. The results will identify the urban spatial patterns in downtown of Nanjing by mapping the characteristics of plot size, shape, properties and boundary lines. Therefore, the method on describing urban spatial configuration in modern cities could be developed.This research is funded by National Natural Science Foundation of China (No. 51538005).Gu, Y.; Tang, L.; Ding, W. (2018). Identify Urban Spatial Patterns Based on the Plot Shapes and Building Setting in Downtown of Nanjing. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 1431-1437. https://doi.org/10.4995/ISUF2017.2017.5924OCS1431143

Ventilation Potential Assessments for Residential Building Arrangements Based on Exceedance Probability Analysis

In this study, the building ventilation potentials were assessed at building group level. Exceedance probability analysis was applied to estimate the uncertainties associated with the influence of climate on wind environment. The criterion was proposed based on building facade pressures. Tw o typical residential building arrangements were investigated. Simulation results show that facade pressure based exceedance probability are efficient in assessing the natural ventilation potentials of building groups and building height variations are important for improving building natural ventilation potentials

Protective effects of ischemic postconditioning on intestinal mucosa barrier function in rabbits with crush injury of hind limb: an experimental study

AbstractObjectiveTo explore the protective effects of two types of ischemic postconditioning (IP) on intestinal mucosa barrier in rabbits with crush injury of the hind limb.MethodsThis study was conducted between August and December 2008 in the Department of Trauma Surgery, Daping Hospital, Third Military Medical University, Chongqing, China. The model of crush injury to the hind limb of rabbits was firstly developed by a 25 kg object with the right hind limbs fixed by wooden splints, and then two types of IP were established, including occluding/opening the common iliac artery and vein alternatively (traditional IP, IP A) and binding/loosening the proximum of the injured hind limb alternatively (modified IP, IP B). Thirty-six male New Zealand white rabbits were randomly divided into three groups: IP A group, IP B group and control group, with 12 rabbits in each group. The serum levels of diamine oxidase (DAO) and intestinal fatty acid-binding protein (I-FABP) were detected at 2, 6, 12 and 24 hours after injury. Pathological changes of ileum were examined at 24 hours after injury.ResultsThe serum levels of I-FABP at 2, 6, 12 and 24 hours after injury in both IP A and IP B groups had a significant decrease, compared with control group. DAO levels also showed the same change trend at 2 and 6 hours after injury, but showed no significant difference between two IP groups. No difference in pathological changes of ileum was found among the three groups.ConclusionsIP can protect intestinal mucosa barrier function on the model of hind limb crush injury in rabbits. Meanwhile the modified IP B shows the same protection as the traditional IP A, and is worth applying in clinic

Bio-inspired design to support reduced energy consumption via the ‘light weighting’ of machine system elements

A potential technique to reduce the energy required to actuate moving parts in a machine is to reduce their mass. This paper presents initial research attempting to answer this question for robotic arm application using a biologically inspired approach. Investigation identified some potential biological solutions for tubular structures. From analysis of the properties of these biological models, the physical principles were deduced and abstracted into computer-aided design models for testing using finite element analysis. Three of the best performing design solutions were manufactured and physically tested. Findings showed that the biomimetic structures reached at least the same efficiency of conventional tubular structures regarding the ratio of maximum load and weight

Poly[[hepta-μ2-aqua-bis­(μ2-pyrazine-2-carboxyl­ato)dibarium] bis­(pyrazine-2-carboxyl­ate)]

In the layered title coordination polymer, {[Ba2(C5H3N2O2)2(H2O)7](C5H3N2O2)2}n, the coordination geometries around the two independent BaII ions can be described as bicapped square-anti­prismatic [BaNO9] arrangements. A two-dimensional polymeric framework with (6,3) topology can be observed in the ac plane, the nodes being provided by BaII ions and the connectors being N and O atoms belonging to pyrazine-2-carboxyl­ate ligands and O atoms of bridging water mol­ecules. Non-coordinating pyrazine-2-carboxyl­ate ions are located between the polymeric layers in the crystal and are interconnected through extensive O—H⋯N,O hydrogen bonding