A parametric study on the effects of displacer-cylinder-circumferential-wall thermal conditions on the performance of a γ-type LTD Stirling engine

ABSTRACT

Regarding a Stirling engine’s heat source and heat sink, most of the studies in the literature focus only on the magnitude of temperature difference between them. However, different Stirling engines adopt very different heat-source and heat-sink configurations. This study is aimed at understanding the effects of different displacer-cylinder-wall thermal conditions on engine performance using computational fluid dynamics (CFD). Results include p–V diagrams, heat flux distributions, temperature variations, and effects of three displacer-cylinder-wall parameters on indicated power and efficiency. It is found that the thermal conditions on the displacer-cylinder-circumferential wall (DCCW) impose significant effects on engine performance. Within the ranges of parameters investigated in this study, extending the coverage of heat source and heat sink on this wall improves up to 28% in indicated power at the cost of losing about 10% in efficiency, proving the significance of DCCW conditions on engine performance.     

Seismic vulnerability indices of ground for Değirmendere (Kocaeli Province,Turkey)

Bulletin of Engineering Geology and the Environment - It is well known that the mechanical and physical properties of subsoil layers as well as poor construction practices play an important role in...     

A study on the spread of fire caused by the stack effects of patio—A computer modeling and a reconstruction of a fire scenario

This study reported an actual building fire incidence for a ten-story building that occurred in Taiwan in 2008. Due to the stack effects the fire occurred on the third floor spread through the patio in a short time to the upper floors and caused three deaths in a tenth floor apartment. This study also attempted to reconstruct the actual fire scenario using computer simulation. The spread of the fire to the combustibles due to hot smoke was accounted for in the simulation. Variation of the fire scenario and the factors causing the fire spread were studied. It was found that an initial fire size below 1.0 MW would not generate sufficient hot smoke to cause fire spread despite the stack effects. However, any obstructions in the patio such as window shading has been found to cause heat accumulation that would aggravate the fire spread problem. The presence of a canopy at the top of the patio can cause higher concentration of smoke for the upper floors. The simulation results are found to be in good agreement with the actual incidence. Moreover the simulation results also show that when the fire spread through the patio the initial fire size of 1.0 MW at the fire site can grow to a building fire of 300 MW.     

A study on the comprehensive indicator of indoor environment assessment for occupants’ health in Taiwan

This paper presents the methodology of developing the comprehensive indicator for indoor-environment assessment. It intends to provide the occupants with the measures of indoor-environment quality. These indicators were drawn up by literature review based on the practicability, economic and feasible aspects. The categories we considered included acoustics, vibrations, illumination, thermal comfort, indoor air quality, water quality, greens and electromagnetic fields. The purpose is to derive the essential indicators through expertise consultation for quantitative assessment on existing buildings. The analytic hierarchy process (AHP) method was used to carry out the weighting among the categories and these indicators in the same category respectively. The consistency ratio was also calculated to filter out the null questionnaire. Finally, a comprehensive index, indoor environment index (IEI_(AHP)), composed of the filtered indicators, is proposed to assess the indoor-environment in the built buildings.     

Estimation of environmental impacts on the water quality of Incesu-Dokuzpınar Springs in Kayseri,Turkey

Industrial and agricultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO₃, N₂, Cl, SO₄, H⁺, K, Mg, Ca, Fe, Cu, B, Pb and Zn, as well as a wide variety of pesticides and other organic compounds. For reactive contaminants like NO₃, it is recommended that a combination of hydrochemical and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. The water type of ncesu-Dokuzpnar Springs is mainly Na–Mg–Ca–Cl–HCO₃. Note that the water types of the Springs were directly related to the hydrogeochemical properties of outcrops at the study area. Thus, the high concentration of Ca⁺² and HCO₃ is mainly related to the high CO₂ contents in the marbles, whereas the high Na concentration arises from the existing syenite, volcanic ash, basalt and clay units, although the ncesu-Dokuzpnar Springs cover most of the drinking and irrigation water demands at the study area. Therefore, relevant hydrogeochemical and statistical studies were carried out for estimating the mentioned environmental impacts on the water quality of ncesu-Dokuzpnar Springs.     

Grouting a tunnel cave-in from the surface: a case study on Kurtkulağı irrigation tunnel,Turkey

This paper describes the treatment of tunneling problems at Kurtkulağı irrigation tunnel, particularly focusing on the Kurtkulağı tunnel which is 1255 m in length and 3.50 m in diameter, is an important of the Yumurtalık Plain Irrigation Project. The tunnel was excavated using conventional dull and blast, but during the tunneling problems occurred. Within a 70 m long section of the tunnel, cave-in occurred at two locations both along the fault zone in tunnel alignment. Slope stability problems were experienced too at inlet and outlet section of the tunnel. A sinkhole was formed at the surface as a result of the cave-in. There are an Allocthonous Cretaceous complex sequence and Miocene sandstone–claystone units, which have a faulty contact in the tunnel alignment area. The complex sequence consists of mainly weathered andesite, spilitic agglomerate, radiolarite, serpentinite and limestone blocks. The claystone to sandstone is thin-medium bedded and has medium-weak rock substance properties. The fault zone with an approximate width of 150 m and consisting of extremely weak crushed rocks crosses the tunnel alignment at mid-section. Some treatment methods were applied to remedy this collapse. Cut and cover method was applied for the first 955 m of the tunnel inlet due to the shallow overburden and very weak rock properties. However, cave-ins delayed the tunnel construction for 1 year and increased the cost by 9%.     

Silver bullet or trojan horse? The effects of inclusionary zoning on local housing markets in the United States

Many local governments are adopting inclusionary zoning (IZ) as a means of producing affordable housing without direct public subsidies. In this paper, panel data on IZ in the San Francisco metropolitan area and suburban Boston are used to analyse how much affordable housing the programmes produce and how IZ affects the prices and production of market-rate housing. The amount of affordable housing produced under IZ has been modest and depends primarily on how long IZ has been in place. Results from suburban Boston suggest that IZ has contributed to increased housing prices and lower rates of production during periods of regional house price appreciation. In the San Francisco area, IZ also appears to increase housing prices in times of regional price appreciation, but to decrease prices during cooler regional markets. There is no evidence of a statistically significant effect of IZ on new housing development in the Bay Area.     

Experimental evaluation of rainwater quality for non-potable applications in the city of São Paulo,Brazil

This study summarizes the evaluation of rainwater quality and its potential for non-potable applications in the city of São Paulo, Brazil. An experimental system was installed at the Centro de Técnicas de Construção Civil (Civil Construction Techniques Centre, Escola Politécnica, University of São Paulo) such that analysis of the physical, chemical and bacteriological composition of rainwater—total and faecal coliforms, Clostridium Sulphite-reducer, Enterococcus and Pseudomonas aeruginosa—could be conducted. The need for water treatment was also evaluated in order to match quality to specific uses. Rainwater samples were collected from the roof by an automatic sample collector. Samples were also collected from a rainwater storage tank. In the operation of the system, analysis of rainwater's potential use in non-potable applications, such as flushing toilet bowls, was also conducted. The results obtained did not meet recognised quality standards, leading to the conclusion that water disinfection prior to use is required.     

The effects of Seoul’s greenbelt on the spatial distribution of population and employment, and on the real estate market

This paper examines the effects of Seoul’s greenbelt on the distribution of population and employment, and on the real estate market, under the assumption of the complete relaxation of the greenbelt using the random utility-based metropolitan input–output model with an endogenous land market for the Seoul metropolitan area. Simulation results show two important consequences of the greenbelt release. First, the greenbelt release would attract more residents and jobs into greenbelt zones and reduce the population and number of firms in both the central city and outer sides of the greenbelt, thereby implying the reduction of inner city densification and of development beyond the greenbelt. Second, both residential and nonresidential space rents would have declined for the whole metropolitan area from 0.4 to 13.7% had the greenbelt been completely released in 2006, thereby indicating that Seoul’s greenbelt made a contribution to raising space rents by limiting land supply.     

A case study on trace metals in surface sediments and dissolved inorganic nutrients in surface water of Olüdeniz Lagoon-Mediterranean, Turkey

Hydro-chemical parameters (salinity, temperature, pH, dissolved oxygen, nitrate, silicate and phosphate) in seawater and major trace metals (Al, Fe, Mn, Cr, V, Zn, Pb, Cu) in sediments were evaluated for the assessment of quality of seawater and sediments in very small lagoon in Mediterranean, Olüdeniz. Enrichment factors for metals in sediment were in the range of 1.62-8.09, comparable to crustal rock composition. For metals, comparison with literature data revealed relatively low metal concentrations for Olüdeniz sediments. Correlation analyses on the sediment metal data showed strong correlation in between Cr, Fe and Zn. Surface water salinity slightly decreases within the lagoon, indicating that limited fresh waters inflow to the lagoon. In October, the lagoon waters contained very low phosphate concentrations but measurable values of nitrate and silicate, yielding high NO(3)(-)/PO(4)(3-) ratios (90). Very low Chlorophyll-a (biomass indicator) concentrations measured in the lagoon suggest the phosphorus limitation of primary productivity.     

A study on the fish fauna of Oussudu – a rare freshwater lake of South India

Oussudu lake (also called Ousteri) is the largest fresh water lake in the Pondicherry region and a large number of people depend on its water, fish and other produce. The lake is now under serious threat of pollution. The present study on the species, composition and dynamics of the lake fish was conducted in this context. Recommendations pertaining to the management of water quality and fisheries are presented on the basis of the studies described in this paper.     

Understanding the soft side of software projects: An empirical study on the interactive effects of social skills and political skills on complexity – performance relationship

While prior research considers project complexity as a double-edged sword, researchers and practitioners still remain unclear whether project complexity serves as productive or counterproductive ingredient for project performance. Our research brings clarity on the dynamic nature of complexity-performance relationship by integrating social exchange theory with recent developments in project management research to develop and test a novel framework involving interactive roles of social skills and political skills in software-projects. Regardless of calls for further empirical studies, researchers have predominantly neglected the fundamental role of human efforts and human interaction in outlining performance particularly in complex projects. Drawing on a survey based sample of 242 project managers and use of variance based structural equation modeling, the findings illuminate theoretical and practical contributions in better understanding complexities in software-projects performance. In addition, prioritizing human-centric factors i.e. social skills and political skills in supporting complexity- performance relationship further enhances contributions of this research.     

Value of information analysis for site investigation programs accounting for variability,uncertainty and scale effects with the Äspö HRL prototype repository as an example

An important feature of underground projects is the early site investigations, performed as a means to identify and quantify hazards. A methodology is presented for identifying the most cost-effective investigation program among a set of alternatives. Methodologies are presented for both investigation of thermal conductivity in hard rock and collection of rock mechanic data for stress induced spalling problems. The cost-effectiveness of an investigation program is estimated by means of value of information analysis (VOIA). Each investigation program of thermal conductivity is associated with uncertainty due to natural variability and lack of knowledge. These uncertainties are taken into account in a simulation model with the aim to estimate the distribution of thermal conductivity values at different scales. The output is a set of thermal conductivity values from which a design parameter can be estimated. The simplest measure of the value of a site investigation is the expected reduction of uncertainty of the design parameter.The methodology is demonstrated with a case study for the prototype nuclear waste repository at Äspö Hard Rock Laboratory, Sweden. A set of four investigation programs for thermal conductivity were evaluated, and the most effective one identified. The application illustrates that an investigation program may supply very different value to a project, depending on how the objective of the investigation is defined. This is demonstrated by using two different objectives and comparing the results. Practical applications of the methodology on both thermal properties and rock mechanics are discussed, with emphasis on site investigations performed by the Swedish Nuclear Fuel and Waste Management (SKB).     

How does the community resilience of urban village response to the government-led redevelopment? A case study of Tangjialing village in Beijing

Building on the critical resilience literature, this study aims at analyzing how the community resilience (CR) of urban village (UV), which is challenged by multiple natural and socio-economic disturbances such as climate change, land occupation, and industrialization, responses to the government-led redevelopment (GLR) and its hidden mechanism. A conceptual framework incorporating social, economic, institutional/governmental, material domains and community capital was established with reference to the work of Cutter, Burton, and Emrich (2010), and was applied as the conceptual springboard to assess the resilience of Tangjialing village. The results suggested that the GLR in Tangjialing village was generally a successful practice for enhancing CR, which was tightly associated with the economic empowerment for local residents and formalization of informal economic activities and negatively affected by insufficient public engagement. Accordingly, policy implications about enhancing the resilience such as protecting the farmers' “private rights” as landowners, providing employment guidance and assistance and implementing cooperative planning were proposed.     

The impacts of globalization on St. Petersburg: A secondary world city in from the cold?

St. Petersburg has not been successful in overcoming a large number of social and economic obstacles inherited from its Soviet past. St. Petersburg is missing an important set of pre-conditions that are critical to attain a level of global interaction required to be considered for secondary city status in a semi-peripheral country. Only the city's cultural activities appear to qualify the city for world city status. As long as Russia itself remains stuck in transition, world city status for St. Petersburg will remain elusive. The author gratefully thanks the organizers of the Impacts of Globalization on Urban Development conference and the anonymous reviewers of this paper.     

Experimental study on the physico-mechanical properties of Tamusu mudstone – A potential host rock for high-level radioactive waste in Inner Mongolia of China

Tamusu mudstone, located in Bayin Gobi Basin in Inner Mongolia of China, has been selected as a potential host rock for high-level radioactive waste (HLW) disposal in China. A series of tests has been carried out, including X-ray diffraction (XRD) tests, scanning electron microscopy (SEM) tests, disintegration tests, permeability tests and triaxial compression tests, to estimate the physico-mechanical properties of Tamusu mudstone in this work. The mineral composition of Tamusu mudstone was analyzed and it was considered as a stable rock due to its low disintegration rate, i.e. approximately 0.11% after several wet/dry cycles. Based on the results of permeability test, it was found that Tamusu mudstone has a low permeability, with the magnitude of about 10^–20 m². The low permeability makes the mudstone well prevent nuclide migration and diffusion, and might be influenced by temperature. The triaxial tests show that Tamusu mudstone is a stiff mudstone with high compressive strength, which means that the excavation disturbed zone would be smaller compared to other types of mudstone due to construction and operation of HLW repositories. Finally, the properties of Tamusu mudstone were compared with those of Opalinus clay, Callovo-Oxfordian (COx) argillite, and Boom clay to further discuss the possibility of using Tamusu mudstone as a potential nuclear waste disposal medium.     

Modeling groundwater flow in the agricultural area of Gümüşhacıköy (Amasya, Turkey)

The Gümü?hac?köy Plain is the most productive agricultural area in the central/northern part of Turkey. Although the Quaternary/Pliocene granular deposits beneath the Plain have formed an important aquifer/water resource, excessive pumping in the last two decades, mainly for irrigation, has resulted in a significant depletion of the reservoir with some 30% of the total resource being lost in the last 40 years. The paper reports a groundwater flow model developed to allow the sustainability of the groundwater resource to be monitored such that appropriate measures can be undertaken.     

Geogrid reinforcement of ballasted railway superstructure for stabilization of the railway track geometry – A case study

BackgroundThis article deals with a unique topic related to railway infrastructure, civil and geotechnical engineering, and modern materials. In the past 20–30 years, more and more synthetic materials have been applied in engineering and everyday life. Geogrid and geotextile products are adequate for substituting lacking abilities of the soils, and granular materials, mainly low tensile and shear strength, etc. This paper aims to introduce the result of the author's research dealing with investigating the behavior of geogrid-reinforced railway ballast based on a long-term field test in the busiest main railway line in Hungary. The duration of the test is more than eleven years.MethodsFive different types of geosynthetics were installed in the superstructure of the No. 1 main railway line (Kelenföld – Hegyeshalom state border) in Hungary in 2010. More than eleven years have elapsed since the installation. The experiences are formulated in this paper. Mathematical-statistical analysis was performed to compare the (sub)sections with each other and with the designated reference sections where no geogrids were applied.ResultsAs a result of the examination, the author summarized the main differences in the behavior of railway track geometry, and the geometrical deterioration rates, considering the different types of reinforcement products.     

Modelling nitrogen in the Yeşilirmak River catchment in Northern Turkey: impacts of future climate and environmental change and implications for nutrient management

Recent research in catchments of rapidly developing countries such as Brazil and China suggests that many catchments of the developing world are already showing signs of nitrogen pollution reminiscent of past experiences in developed countries. This paper looks at both the individual and combined effects of future climate change and other likely environmental changes on in-stream nitrate concentrations in a catchment in Northern Turkey. A model chain comprised of simulated future temperature and precipitation from a Regional Circulation Model (RCM), a conceptual hydrological model (HBV) and a widely tested integrated catchment nitrogen model (INCA-N) is used to model future changes in nitrate concentrations. Two future periods (2021-2050 and 2069-2098) are compared to the 1961-1990 baseline period in order to assess the effectiveness of several possible interventions available to catchment authorities. The simulations show that in the urbanised part of the catchment, the effects of climate change and other environmental changes act in the same direction, leading to peak nitrate concentrations of 7.5 mg N/l for the 2069-2098 period, which corresponds to a doubling of the baseline values. Testing different available policy options reveals that the installation of wastewater treatment works (WWTWs) in all major settlements of the catchment could ensure nitrate levels are kept at near their baseline values for the 2021-2050 period. Nevertheless, a combination of measures including WWTWs, meadow creation, international agreements to reduce atmospheric N concentrations and controls on agricultural practises will be required for 2069-2098. The approach presented in this article could be employed in order to anticipate future pollution problems and to test appropriate solutions, some of which will necessitate international co-operation, in other catchments around the world.     

A Preliminary Research on the City Planning of “Yin”,Capital of the Shang Dynasty

“Yin”was the capital of Shang Dynasty.On the basis of archaeological findings,theauthor explored the planning and layout,distributions of city functions,structural patternsand so on of this capital of the China's slave society 3,000 years ago from the viewpoint ofcity planning.Through analysing the detailed layout of the imperial palaces,residentialareas,handicraft workshops and imperial tombs of the ancient capital city from the thensocial and economic background,the author believes that the city planning concept of theancient“Yin”township has far-reaching influence on the city planning of different dynas-ties in Chinese history.