Rapid urban development and national master planning in Arab Gulf countries. Qatar as a case study

In this article we review past and current master planning efforts in Qatar, highlighting the country’s inability to manage rapid urban development. We will argue that the failure to implement sound urban planning in Qatar – and by extension, in the rest of the Arab Gulf Region – is the result of a detachment between the master planning phase – usually sub-contracted to external consultants that are insensitive to Gulf dynamics – and the implementation phase – usually carried out by incapable and redundant local government agencies – all in absence of a serious discussion of ongoing mega-projects.     

新型快速换产滚齿夹具

为了满足市场的多方位需求,生产齿轮的种类繁多,经常会更换加工产品。而换产时间的缩短,能极大地提升生产效率。考虑到每次换产调试夹具,主要是对定位锥、支撑座、压盖和压套的安装调试。针对这几个部件,设计一个新的快速换产滚齿夹具,实现了快速装夹、快速找正、快速调试,从而达到快速换产的目的。     

Rapid setup of hydrological and hydraulic models using OpenStreetMap and the SRTM derived digital elevation model

A stepwise procedure has been developed in Python to extract information from OpenStreetMap (OSM) for hydrological and hydraulic models using existing and newly developed tools. The procedure focuses on the extraction of paved areas and water bodies. Road density is used to fill in gaps in OSM polygon coverage. Furthermore, it includes automatic downloading of Shuttle Radar Topography Mission (SRTM) elevation data and improving the elevation model with man-made landscape features such as elevated roads that are sampled from OSM. This is useful for hydraulic modelling in data scarce flood plain areas, where sharp elevation differences are dominated by man-made elevated elements. Test cases in Europe, South East Asia and East Africa demonstrate the potential of the procedure, although large differences in completeness of OSM coverage suggest it is best used in combination with other data sources.     

BIT: Biosignal Igniter Toolkit

The study of biosignals has had a transforming role in multiple aspects of our society, which go well beyond the health sciences domains to which they were traditionally associated with. While biomedical engineering is a classical discipline where the topic is amply covered, today biosignals are a matter of interest for students, researchers and hobbyists in areas including computer science, informatics, electrical engineering, among others. Regardless of the context, the use of biosignals in experimental activities and practical projects is heavily bounded by the cost, and limited access to adequate support materials. In this paper we present an accessible, albeit versatile toolkit, composed of low-cost hardware and software, which was created to reinforce the engagement of different people in the field of biosignals. The hardware consists of a modular wireless biosignal acquisition system that can be used to support classroom activities, interface with other devices, or perform rapid prototyping of end-user applications. The software comprehends a set of programming APIs, a biosignal processing toolbox, and a framework for real time data acquisition and postprocessing.     

Polymeric scaffolds for cardiac tissue engineering: requirements and fabrication technologies

Cardiac tissue engineering (TE) is an emerging field, whose main goal is the development of innovative strategies for the treatment of heart diseases, with the aim of overcoming the drawbacks of traditional therapies. One of these strategies involves the implantation of three‐dimensional matrices (scaffolds) capable of supporting tissue formation. Scaffolds designed and fabricated for such application should meet several requirements, concerning both the scaffold‐forming materials and the properties of the scaffold itself. A scaffold for cardiac TE should be biocompatible and biodegradable, mimic the properties of the native cardiac tissue, provide a mechanical support to the regenerating heart and possess an interconnected porous structure to favour cell migration, nutrient and oxygen diffusion, and waste removal. Moreover, the mimesis of myocardium characteristic anisotropy is attracting increasing interest to provide engineered constructs with the possibility to be structurally and mechanically integrated in native tissue. Several conventional and non‐conventional fabrication techniques have been explored in the literature to produce polymeric scaffolds meeting all these requirements. This review describes these techniques, with a focus on their advantages and disadvantages, and their flexibility, with the final goal of providing the reader with the primal knowledge necessary to develop an effective strategy in cardiac TE. © 2013 Society of Chemical Industry     

Designing a toxic-element-free Ti-based amorphous alloy with remarkable supercooled liquid region for biomedical application

A series of toxic-element-free Ti–Zr–Ta–Si amorphous alloy ribbons have been successfully prepared by melt-spinning. The differential scanning carlorimetry (DSC), X-ray diffraction analysis, bending test and microhardness test are conducted for studying the thermal and mechanical properties. The results show that the Ti₄₂Zr₄₀Ta₃Si₁₅ metallic glass ribbon present excellent ductile behavior by the bending testing, without any fracture cracking after bending over 180 degree. In addition, this amorphous alloy possesses a very high glass transition and crystallization temperature of 799 and 898 K, respectively, as well as a very wide supercooled liquid region of 99 K. This amorphous alloy exhibits promising thermal stability during isothermal annealing at the middle temperature of its supercooled region, with more than 3000 s incubation time for isothermal annealing at 823 K (550 °C). This amorphous alloy also shows much lower value of corrosion current density (2.27 × 10⁻⁹ A/m²) than the 304 stainless steel in the 0.3 mass% sodium cloride solutions. This Ti₄₂Zr₄₀Ta₃Si₁₅ alloy is believed to be a promising based alloy for fabricating the bulk metallic glass foam by the spacer technique in the application of biomedical implants.     

A multi-layered two-dimensional finite element model to calculate dynamic product heat load and weight loss during beef chilling

A model for predicting the dynamic product heat load and weight loss during beef chilling has been developed using finite element analysis. The beef geometry is approximated by 13 sections, each represented by a two-dimensional finite element grid using triangular elements. Longitudinal heat conduction was neglected. The model was tested against data from 55 industrial beef chilling trials covering a wide range of carcass size, fat cover and chilling conditions. The heat removal during the first 2 h predicted by the model was on average 5.6% higher than the experimental value. The average percentage error in the predicted weight loss after 20 h was 2.3%.     

快速成型在CAD的应用

本文阐述ＲＰ快速成型的原理及在ＣＡＤ的应用。简单介绍了ＲＰ快速成型ＣＡＤ系统的基本流程，着重讲述了从制三维模型到模型介面转换再到产品的加工成型过程，并展望该项技术的发展趋势。     

纺织机件器材的新型修复技术(五)--快速成型技术的应用

论述了快速成型技术在企业产品开发、模具及功能零件的制造方面的应用.该技术展示了一种全新的加工体系,市场前景十分广阔.     

Rapid prototyping and flow simulation applications in design of agricultural irrigation equipment: Case study for a sample in-line drip emitter

In this study, a 3D CAD solid model of a sample agricultural irrigation emitter was created and the flow behaviour was simulated in its labyrinth channels by using a flow simulation technique. Referenced by the original design, the channel geometry was modified and the emitter was re-fabricated using rapid prototyping/additive manufacturing techniques. The flow behaviour is then re-investigated based on the re-shaped channel geometry of the labyrinth structure. The predetermined optimum pressure in the pipe was validated experimentally for both the original design and modified designs. As a result, the optimum pressure in the pipe and the flow characteristics for original both the design and modified designs of the emitter were validated. This study contributes to further research into the development of agricultural irrigation equipment aided through the utilisation of additive manufacturing and computer aided engineering tools.