The impact of urbanization policy on land use change: A scenario analysis

The rapid urbanization has led to extensive land use change particularly in those developing countries. In line with the development of urbanization, arable land is decreasing dramatically, which presents the threat to the food security for human being. It is therefore essential to understand the level of impacts of urbanization on the land use change. This paper introduces a dynamic systems based method for assessing the impacts of urbanization policy on land use change with reference to the urbanization practice in China. Four typical policy scenarios are identified in implementing urbanization in China, including balanced development driven by planning, uneven development driven by planning, balanced development driven by market and uneven development driven by market and their impacts on land use change are analyzed through a dynamic system model. Land use change is considered as a dynamic system model composing five subsystems: urbanization, social, economic, environmental and land use subsystems. The key attributes in these five subsystems are interactive and they are dynamic variables. The assessment on the impacts of urbanization policy to land use change is demonstrated through employing the software iThink to the land use change dynamic model, using the data collected from the Jinyun County in China. The findings suggest that the urban construction land will continue to increase in the foreseeable future in China, whilst the agricultural land will gradually decrease. Nevertheless, different policy scenarios will have different impacts on these land changes. Thus decision makers can adopt different policies to control the rate of land use change.     

A total environmental risk assessment model for international hub airports

This paper presents a multi-criteria decision analysis for environmental risk assessment (ERA) with regard to avoiding and eliminating damages and loss under natural disasters in international airport projects. It starts from an assumption that the strategy of eliminating damages and losses under natural disasters is related to the location selection problem, and it is necessary to use the multi-criteria decision analysis for calculated decision-making support. The paper uses the analytic network process (ANP) to demonstrate one of its utility modes in decision-making support to location selection problems, which aims at an evaluation of different projects from different locations. A set of generic criteria for risk assessment at international projects was put forward to support ANP modelling, and it was due to the consideration of social, technical, economic, environmental and political (STEEP) criteria related to the built, social and natural (BSN) trinity environment of international airport projects. At the end, an experimental case study on three international hub airports in China is given to test the ANP model called ERA.Airport, and it is concluded that ANP can be effectively used for risk assessment in the specific utility mode. The ERA.Airport is a generic multi-criteria decision-making model and can be used across the world for accurate environmental risk assessment for international airports.     

An investigation of the block shear strength of coped beams with a welded clip angle connection — Part II: Numerical study

An experimental study of the block shear capacity of ten full-scale coped beams with a welded clip angle connection was presented in Part I. The test results were compared with predictions using block shear design equations in several current design standards. In general, the results showed that the existing design standards did not provide consistent predictions of the block shear capacity of coped beams with welded clip angles. In addition, the equations provided by the standards cannot accurately reflect the failure mode of the specimens observed in the tests. In order to gain a better understanding of the connection behavior, such as the stress distribution in the web near the periphery of the clip angles and the failure mechanism of the connection, an analytical study of the block shear capacity of coped beams with welded clip angles was carried out using the finite element method. Based on the limited test data and the results of the finite element analysis (FEA), a strength model was established and a design equation was proposed to evaluate the block shear strength of coped beams with welded clip angles. It was shown that the proposed design equation gave better predictions of the block shear capacity of the specimens.     

Dynamic planning and control methodology for strategic and operational construction project management

This paper introduces the system's perspective of the dynamic planning and control methodology (DPM), aimed to support both the strategic and the operational aspects of project management. For this objective, a new modeling framework that integrates system dynamics and network-based tools is presented in this paper. The proposed framework adopts system dynamics as a core simulation engine for strategic project management and network-based tools as a wrap layer for operational project management. To implement the DPM framework, a web-based system has been developed within a collaborative environment. The developed system provides great support to both the strategic and operational aspects of project management by integrating familiar network concepts with system dynamics to analyze the overall strategic and operational project performance.     

Measuring accessibility and utilization of public spaces in Famagusta

Public spaces have a central role, both physically and functionally, in urban planning and development. Many urban theorists state their significant role as one of the principal components of a healthy urban setting. This is in addition to their functional role, when they increase a sense of community when intensive social interaction takes place in these areas. However, recently, they have started to lose significance, when they are neglected in the urban planning process, or when existing spaces are lost. Additionally, accessibility and utilization of these areas decreases, since public spaces are neglected in urban planning and development processes. In this study, public spaces are assessed in terms of accessibility and utilization, regarding the effects of rapid urban growth on their physical and functional structure. This study first evaluates the significance of public spaces in an urban setting; second, determines the variables effective in terms of their accessibility and utilization; third, assesses the factors affecting the accessibility and utilization of public spaces through a questionnaire survey on the role of public spaces in social interaction, and concludes with an evaluation of the results and suggestions for further research.     

Promoting an urban renaissance in England and the Netherlands

Recent government policy documents in both England and the Netherlands make reference to the need to promote urban living and working—an ‘urban renaissance’. Promoting urban living and working offers various potential benefits such as improving urban vitality, reducing the need to travel and using land more efficiently. Nevertheless, promoting urban living and working is still problematic and there is widespread belief within Europe (especially in northern Europe) that ‘non-urban’ areas (that is to say areas outside large urban centres—suburbs, small towns and more rural areas) are more attractive in terms of a better environment, lower levels of crime and a greater sense of community for example. In addition, there is a variety of obstacles to promote urban living and working which currently reduce the chance of achieving such a renaissance. This paper gives an overview of recent national policies in England and the Netherlands that attempt to promote urban living and working, focusing particularly on policies for mixed-use development as one means of achieving an urban renaissance. Policy obstacles are identified and discussed, and potential ways of overcoming these obstacles are proposed.     

Energetic and exergetic analyses of a combined system consisting of a high-temperature polymer electrolyte membrane fuel cell and a thermoelectric generator with Thomson effect

A combined system model consisting of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC), a regenerator and a thermoelectric generator (TEG) is proposed, where the TEG is applied to harness the generated waste heat in the HT-PEMFC for extra electricity production. The TEG considers not only the Seebeck effect and Peltier effect but also the Thomson effect. The mathematical expressions of power output, energy efficiency, exergy destruction rate and exergy efficiency for the proposed system are derived. The energetic and exergetic performance characteristics for the whole system are revealed. The optimum operating ranges for some key performance parameters of the combined system are determined using the maximum power density as the objective function. The combined system maximum power density and its corresponding energy efficiency and exergy efficiency allow 19.1%, 12.4% and 12.6% higher than that of a stand-alone HT-PEMFC, while the exergy destruction rate density is only increased by 8.6%. The system performances are compared between the TEG with and without the Thomson effect. Moreover, the impacts of comprehensive parameters on the system performance characteristics are discussed. The obtained results are helpful in developing and designing such an actual combined system for efficient and clean power production.     

Demonstration of hydrogen production in a hybrid lignite-assisted solid oxide electrolysis cell

A Ni-YSZ/YSZ/Ag–Pt cell was used to demonstrate the concept of high temperature lignite-assisted electrolysis in hybrid (combined solid oxide and molten carbonate) operation. To assess the performance of the hybrid concept, the same cell was also used for lignite-assisted electrolysis in absence of an anodic carbonate load, as well as for fuel cell measurements using H₂ and lignite as fuels, the latter both with and free of molten carbonates. In fuel cell operation, the hybrid direct lignite fuel cell obtained 45% higher maximum power density than the H₂ fed SOFC and 160% higher power density than the lignite fuel cell without carbonates. For high temperature electrolysis, the hybrid concept of admixed lignite and carbonates at the anode led to a 350% higher current density (up to 508 mA∙cm⁻², at 1.95 V), compared to the lignite-assisted operation in absence of carbonates (145 mA∙cm⁻², at 1.95 V). Thus, the anodic addition of carbonates within the same cell, increased H₂ production 3.5 times. This was accompanied by an equivalent increase of the anodic fuel consumption, and the cell's efficiency was essentially unaffected. Nonetheless, significant anodic and cathodic resistances at low overpotentials restricted electrolysis performance and efficiency, in either the absence or the presence of carbonates. These resistances, most likely due to both the cathodic steam activation and the anodic “shuttle” of the CO intermediate, were drastically alleviated at higher overpotentials. The presence of carbonates caused an earlier and more rapid decrease of the anodic area specific resistance, to much lower values at high overpotentials, resulting in the considerably higher performance of the hybrid mode.     

Performance and long-term durability of direct-methane flat-tube solid oxide fuel cells with symmetric double-sided cathodes

In this work, we investigated the performance and stability of a large flat-tube SOFC with symmetric double-sided cathodes (DSC), which was directly fueled with methane. The effect of steam/carbon (S/C) ratio, temperature, and current density on the performance, and long-term stability of the DSC as well as the catalytic behavior of the anode was investigated in details. The thick anode support and inner channels of the DSC formed an efficient microreactor for steam-reforming of methane, resulting in high conversion rate of methane and CO selectivity. In particular, when the S/C was 2, the conversion of CH₄ at 750 °C achieved 100% in the DSC and no carbon deposition was observed. Moreover, the voltage of DSC with was stable throughout 190 h under a discharge current density of 0.257 A cm⁻².